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14.1E: Xost xavf omillari - Biologiya

14.1E: Xost xavf omillari - Biologiya


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Zaif, kasal, to'yib ovqatlanmaydigan, saraton kasalligiga chalingan yoki diabetga chalingan odamlar surunkali yoki doimiy infektsiyalarga nisbatan sezgirlikni oshiradilar.

O'quv maqsadlari

  • Kasallik ehtimolini oshiradigan xavf omillarini tan oling

Asosiy nuqtalar

  • INFEKTSION xavfi hamshiralik tashxisidir; "Insonga endogen yoki ekzogen manbalardan opportunistik yoki patogen agent (virus, qo'ziqorin, bakteriyalar, protozoa yoki boshqa parazit) tomonidan hujum qilish xavfi mavjud bo'lgan holat" xavfning diagnostik ta'rifidir.
  • Xavf omillariga misollar: kasallikdan keyin immunitetning pasayishi, periferik qon tomir kasalliklari tufayli ikkinchi darajali qon aylanishining buzilishi, jarrohlik natijasida terining yaxlitligi yoki yuqumli agentlar bilan takroriy aloqa qilish.
  • Qo'l yuvish, xalat kiyish va yuz niqoblarini kiyish kabi usullar infektsiyalarning jarrohdan bemorga yoki aksincha o'tishining oldini olishga yordam beradi.

Asosiy shartlar

  • opportunistik infektsiya: Kasallikni keltirib chiqaradigan va faqat uy egasining immuniteti zaiflashganda yuzaga keladigan har qanday infektsiya.
  • kolit: yo'g'on ichakning yallig'lanishi.
  • emlash: ma'lum bir kasallik yoki kasallikning shtammidan himoya qilish uchun vaktsina bilan emlash.

Aksariyat odamlar osonlikcha yuqmaydi. Zaif, kasal, to'yib ovqatlanmaydigan, saraton kasalligiga chalingan yoki diabetga chalinganlar surunkali yoki doimiy infektsiyalarga nisbatan sezgirlikni oshiradilar. Immunitet tizimi sust bo'lgan yoki immunosupressiv dorilarni qabul qiladigan odamlar opportunistik infektsiyalarga ayniqsa moyil.

INFEKTSION xavfi - bu hamshiralik tashxisi bo'lib, u "shaxsga endogen yoki ekzogen manbalardan opportunistik yoki patogen agent (virus, qo'ziqorin, bakteriyalar, protozoa yoki boshqa parazit) tomonidan hujum qilish xavfi ostida bo'lgan holat" sifatida tavsiflanadi. ” INFEKTSION xavfi bir qator endogen manbalarga bog'liq. Kesishdan terining shikastlanishi bemorning infektsiya xavfini oshirishi mumkin, shuningdek, juda yosh yoki qarilik, mos ravishda sodda yoki zaif immunitet tufayli. Xavf omillariga kasallik natijasida kelib chiqqan immunitetning pasayishi, periferik qon tomir kasalliklari tufayli qon aylanishining buzilishi, jarrohlik natijasida terining yaxlitligi yoki yuqumli agentlar bilan takroriy aloqa qilish kiradi.

Xavfni kamaytirish

Qo'l yuvish, xalat kiyish va yuz niqoblarini kiyish kabi usullar jarroh va bemor o'rtasida infektsiyani yuqtirishning oldini olishga yordam beradi. Tez-tez qo'l yuvish kiruvchi organizmlarning tarqalishiga qarshi eng muhim himoya bo'lib qolmoqda. Xavfni kamaytirish uchun yaxshi ovqatlanish kerak. Sog'lom turmush tarzi ham shunday. Noqonuniy giyohvand moddalardan voz kechish, prezervativdan foydalanish va jismoniy mashqlar dasturiga kirish orqali odam xavf omillarini yaxshilashi mumkin. Oziq-ovqatlar tavsiya etilgan haroratgacha pishirilishi kerak; uzoq vaqt davomida tashqarida qoldirilgan ovqatlardan saqlaning. Antibiotiklarni kerak bo'lgandan ko'proq vaqt yoki kerak bo'lmaganda qabul qilmaslik kerak - antibiotiklardan uzoq muddat foydalanish qarshilikka olib keladi va clostridium difficile kolit kabi opportunistik infektsiyalarni rivojlanish ehtimolini oshiradi. Emlash - bu emlangan uy egalarida immunitetning rivojlanishini rag'batlantirish orqali infektsiyalarning oldini olishning yana bir muhim vositasidir.


Yuqumli bo'lmagan kasalliklar

Surunkali kasalliklar deb ham ataladigan yuqumli bo'lmagan kasalliklar (NCD), odatda uzoq davom etadi va genetik, fiziologik, atrof-muhit va xulq-atvor omillarining kombinatsiyasi natijasidir.

NCD ning asosiy turlari yurak-qon tomir kasalliklari (yurak xurujlari va insult kabi), saraton, surunkali respirator kasalliklar (masalan, surunkali obstruktiv o'pka kasalligi va astma) va diabetdir.

NCDlar nomutanosib ravishda past va o'rta daromadli mamlakatlardagi odamlarga ta'sir qiladi, bu erda global NCD o'limlarining to'rtdan uch qismidan ko'prog'i &ndash 31,4 million &ndash sodir bo'ladi.


Saratonga irsiy sezuvchanlik sindromlari uchun genetik test

Genetika testi inson genlarida o'ziga xos irsiy o'zgarishlarni (variantlarni) qidiradi. Genetik variantlar kasalliklarning rivojlanish xavfiga zararli, foydali, neytral (ta'siri yo'q) yoki noma'lum yoki noaniq ta'sir ko'rsatishi mumkin. Ma'lumki, ba'zi genlardagi zararli variantlar saraton rivojlanish xavfini oshiradi. Ushbu irsiy variantlar barcha saraton kasalliklarining taxminan 5-10 foizini tashkil qiladi.

Saraton ba'zan "oilalarda uchraydi" kabi ko'rinishi mumkin, hatto u merosxo'rlikdan kelib chiqmasa ham. Masalan, umumiy muhit yoki turmush tarzi, masalan, tamaki iste'moli, oila a'zolari o'rtasida shunga o'xshash saraton rivojlanishiga olib kelishi mumkin. Biroq, oila a'zolarida ko'rinadigan ba'zi naqshlar, masalan, rivojlanayotgan saraton turlari, boshqa saraton bo'lmagan holatlar va saraton odatda rivojlanadigan yosh - saraton kasalligiga irsiy moyillik mavjudligini ko'rsatishi mumkin. .

Ma'lum bo'lgan ko'plab irsiy saraton sezuvchanlik sindromlarida ishtirok etgan genlar aniqlangan. Kimdadir ushbu genlardan birida zararli variant borligini tekshirish, bu holat haqiqatan ham irsiy sindromning natijasi ekanligini tasdiqlashi mumkin. Genetika tekshiruvi, shuningdek, saraton kasalligiga chalinmagan (hali) oila a'zolarining zararli (saratonga moyil bo'lgan) varianti borligi ma'lum bo'lgan oila a'zolari bilan bir xil variantni meros qilib olganligini aniqlash uchun ham o'tkaziladi.

Ba'zida saraton tashxisi qo'yilgan odamlarning saraton hujayralarida davolanishni boshqarish uchun ishlatilishi mumkin bo'lgan genetik o'zgarishlar bor yoki yo'qligini aniqlash uchun o'simta DNK sekvensiyasi deb ataladigan boshqa turdagi genetik tekshiruv o'tkaziladi. Ushbu saraton hujayralari o'zgarishlarining ba'zilari irsiy bo'lishi mumkin bo'lsa-da, ularning aksariyati inson hayoti davomida tasodifiy sodir bo'ladi. O'simta hujayralarining genetik tekshiruvi Saratonni davolash uchun biomarker testi sahifasida ko'rib chiqiladi.

Saratonga moyillik variantini meros qilib olgan kishi har doim saraton kasalligiga chalinadimi?

Yo'q. Hatto oilada saratonga moyillik varianti mavjud bo'lsa ham, bu variantni meros qilib olgan har bir kishi saraton kasalligiga chalinishini anglatmaydi. Variantga ega bo'lgan odamning saraton kasalligini rivojlanishiga bir nechta omillar ta'sir qiladi. Ulardan biri kirish variantidan. Variantga ega bo'lganlarning hammasi ham ushbu variant bilan bog'liq kasallikni rivojlantirmasa, u to'liq bo'lmagan yoki pasaygan penetratsion deb ataladi. Irsiy saraton sindromlari ham turlicha bo'lishi mumkin ekspressivlik-ya'ni, bu variantni meros qilib olgan odamlar sindromning belgilari va alomatlarini namoyon qilish darajasida, shu jumladan saraton kasalligining rivojlanishida farq qilishi mumkin. Turmush tarzi omillari va ekologik xavflar kasallikning namoyon bo'lishiga ham ta'sir qilishi mumkin.

Saraton xavfini baholash uchun qanday genetik testlar mavjud?

50 dan ortiq irsiy saraton sindromlari tavsiflangan, oilaviy saratonga moyillik sindromlari ro'yxati uchun PDQ saraton genetikasi umumiy ko'rinishiga qarang. Ularning aksariyati otosomal dominant tarzda meros bo'lib o'tadigan zararli variantlardan kelib chiqadi, ya'ni ota-onadan biridan meros bo'lib o'tgan genning bitta o'zgartirilgan nusxasi odamda saraton rivojlanish ehtimolini oshirish uchun etarli. Ushbu sindromlarning aksariyati uchun zararli variantlar uchun genetik testlar mavjud.

Sinovlar, shuningdek, nomlangan sindromlar bilan bog'liq bo'lmagan, ammo saraton xavfini oshirishi aniqlangan bir nechta irsiy genetik variantlar uchun ham mavjud. Misollar orasida meros qilib olingan variantlar kiradi PALB2 (ko'krak va oshqozon osti bezi saratoni xavfi ortishi bilan bog'liq), CHEK2 (ko'krak va yo'g'on ichak saratoni), BRIP1 (tuxumdon saratoni) va RAD51C va RAD51D (tuxumdon saratoni).

Saraton xavfi uchun genetik testni kim ko'rib chiqishi kerak?

Oila tarixi ularni saraton kasalligiga olib keladimi yoki yo'qmi, degan xavotirda odamlar genetik maslahatchi bilan maslahatlashishlari kerak.

Shaxsning shaxsiy yoki oilaviy tibbiy tarixining xususiyatlari, ayniqsa kombinatsiyalangan holda, irsiy saraton sindromini ko'rsatishi mumkin:

  • Saraton g'ayrioddiy yoshligida tashxis qo'yilgan
  • Bir odamda bir necha xil saraton turlari paydo bo'lgan
  • Ikkala buyrak yoki ikkala ko'krak kabi juftlashgan organlar to'plamida ikkala organda saraton
  • Bir nechta birinchi darajali qarindoshlar (bir kishining ota-onasi, aka-ukalari yoki bolalari) bir xil turdagi saratonga ega (masalan, ko'krak bezi saratoni bilan og'rigan ona, qiz va opa-singillar) ko'krak yoki tuxumdon saratoni bilan kasallangan oila a'zolarining yo'g'on ichak saratoni bilan kasallangan oila a'zolari. va endometrium saratoni
  • O'ziga xos saraton turining noodatiy holatlari (masalan, erkaklarda ko'krak saratoni)
  • Irsiy saraton sindromlari bilan bog'liq bo'lgan tug'ma nuqsonlarning mavjudligi, masalan, saratonsiz (yaxshi) teri o'sishi va 1-toifa neyrofibromatoz bilan bog'liq skelet anomaliyalari.
  • Irqiy yoki etnik guruhning a'zosi bo'lish, ma'lum bir irsiy saratonga moyillik sindromiga ega bo'lish xavfi va yuqoridagi xususiyatlardan bir yoki bir nechtasiga ega bo'lish.
  • Bir nechta oila a'zolari saraton kasalligiga chalingan

Agar biror kishi o'z oilasida irsiy saratonga moyillik sindromiga ega bo'lishi mumkinligidan xavotirda bo'lsa, odatda, iloji bo'lsa, saraton kasalligiga chalingan oila a'zosiga birinchi navbatda genetik maslahat va testdan o'tishi tavsiya etiladi, bu esa oilada saraton mavjudligini aniqroq aniqlash uchun. irsiy genetik variantga bog'liq. Genetika tekshiruvi, agar u ilgari yoki hozirgi saraton kasalligiga chalingan oila a'zosida hech qachon saraton kasalligiga chalingan bo'lmagan odamda boshlanishi mumkin bo'lsa, ko'pincha ko'proq ma'lumot beradi.

Agar oila a'zolaridan birida irsiy saratonga moyillik sindromi allaqachon aniqlangan bo'lsa, bu variantni meros qilib olishi mumkin bo'lgan har qanday oila a'zolari, hatto saraton kasalligiga (hali) duchor bo'lmagan bo'lsa ham, genetik tekshiruvdan o'tishlari kerak. Ularning xavf-xatarlari haqida bilish ularga kelajakda saraton kasalligining oldini olishga yordam beradi.

Irsiy saraton sindromi uchun genetik tekshiruvda genetik maslahatning roli qanday?

Genetika bo'yicha maslahat odatda irsiy saraton sindromi uchun har qanday genetik testdan oldin tavsiya etiladi va testdan so'ng ham amalga oshirilishi mumkin, ayniqsa ijobiy natija topilsa va odam o'zi aniqlangan irsiy saratonga moyillik sindromi haqida ko'proq ma'lumotga ega bo'lishi kerak bo'lsa. Ushbu maslahat saraton genetikasi bo'yicha tajribaga ega bo'lgan o'qitilgan genetik maslahatchi yoki boshqa sog'liqni saqlash mutaxassisi tomonidan amalga oshirilishi kerak. Genetika maslahati odatda test jarayonining ko'plab jihatlarini qamrab oladi, jumladan:

  • Shaxsning shaxsiy va oilaviy tibbiy tarixiga asoslangan irsiy saraton xavfini baholash
  • Muhokama:
    • Genetik testning maqsadga muvofiqligi va testning mumkin bo'lgan zararlari va foydalari
    • Ijobiy, salbiy va noaniq test natijalarining tibbiy oqibatlari
    • Sinov natijasi informatsion bo'lmasligi mumkin (ya'ni saraton xavfiga ta'siri noma'lum bo'lgan variantni topishi mumkin)
    • Genetik test natijalarining psixologik xavflari va foydalari
    • Variantni bolalarga berish xavfi
    • Sinovning oilaga ta'siri
    • Amalga oshirish uchun eng yaxshi test

    Genetika maslahati, shuningdek, bemor bilan profilaktika va skrining bo'yicha tavsiyalarni muhokama qilish, bemorni qo'llab-quvvatlash guruhlari va boshqa axborot resurslariga yuborish va natijalarni olgan shaxsga hissiy yordam ko'rsatishni o'z ichiga olishi mumkin.

    Ushbu masalalarni o'rganish genetik test uchun ma'lumotli rozilik jarayonining asosiy qismidir. Yozma ma'lumotli rozilik odatda genetik test buyurilishidan oldin olinadi. Odamlar test maqsadi, uning tibbiy oqibatlari, xavf va foydalari, testga mumkin bo'lgan muqobil variantlari va shaxsiy huquqlari haqida aytilgani va tushunilganligi haqida varaqaga imzo chekish orqali rozilik beradi.

    Ko'pgina boshqa tibbiy testlardan farqli o'laroq, genetik testlar nafaqat tekshirilayotgan shaxs haqida, balki uning qarindoshlari haqida ham ma'lumot berishi mumkin. Oila a'zolaridan biri boshqa oila a'zolariga ta'sir qilishi mumkin bo'lgan genetik test natijalarini oshkor qilganda, oilaviy munosabatlarga ta'sir qilishi mumkin. Oila a'zolari kasallik bilan bog'liq genetik variant mavjudligini bilish qanchalik foydali ekanligi haqida turli xil fikrlarga ega bo'lishi mumkin. Oila a'zolarining ba'zilari o'zlarining genetik holatini bilishsa, boshqa oila a'zolari bilishni istamasa, sog'liqni saqlash bo'yicha munozaralar murakkablashishi mumkin. Genetika bo'yicha mutaxassislar bilan suhbat oila a'zolariga duch kelishi mumkin bo'lgan murakkab tanlovlarni yaxshiroq tushunishga yordam beradi.

    Genetik tekshiruv qanday o'tkaziladi?

    Genetik testlar odatda odamning genetik maslahatchisi, shifokor yoki shaxs va oila tarixini ko'rib chiqqan boshqa tibbiy xizmat ko'rsatuvchi provayder tomonidan so'raladi. Sog'liqni saqlash mutaxassisi tanlashi mumkin bo'lgan genetik test variantlari bitta genga qaraydigan va bir vaqtning o'zida bir nechta genlarda zararli variantlarni qidiradiganlarni o'z ichiga oladi. Oxirgi turdagi testlar multigen (yoki panel) testlari deb ataladi.

    Sinov tana suyuqligi yoki to'qimalarining kichik namunasida amalga oshiriladi - odatda qon, lekin ba'zida tupurik, yonoq ichidagi hujayralar yoki teri hujayralari. Keyin namuna genetik tekshiruvga ixtisoslashgan laboratoriyaga yuboriladi. Laboratoriya test natijalarini testni talab qilgan shifokor yoki genetik maslahatchiga qaytaradi. Sinov natijalarini olish uchun odatda bir necha hafta yoki undan ko'proq vaqt ketadi.

    Sog'liqni saqlash sug'urtasi odatda genetik maslahat va ko'plab genetik testlarni o'z ichiga oladi, agar ular tibbiy jihatdan zarur deb hisoblansa. Genetik tekshiruvdan o'tmoqchi bo'lgan shaxs sinovdan oldin shifokor va sug'urta kompaniyasi bilan xarajatlar va tibbiy sug'urta qoplamasini muhokama qilishi kerak.

    Genetik tekshiruv natijalari nimani anglatadi?

    Genetika tekshiruvi bir nechta mumkin bo'lgan natijalarni berishi mumkin: ijobiy, salbiy, haqiqiy salbiy, ma'lumotga ega bo'lmagan salbiy, noaniq ahamiyatga ega variant yoki yaxshi (zararsiz) variant.

    Ijobiy natija. Testning ijobiy natijasi laboratoriyada irsiy saratonga moyillik sindromi bilan bog'liq bo'lgan genetik variant topilganligini anglatadi. Ijobiy natija quyidagicha bo'lishi mumkin:

    • Saraton kasalligiga chalingan odam uchun saraton irsiy genetik variant tufayli yuzaga kelganligini tasdiqlang va davolanishni tanlashga yordam bering.
    • Kelajakda ma'lum saraton(lar)ni rivojlanish xavfi ortib borishini ko'rsating va kelajakdagi boshqaruvni ushbu xavfni kamaytirishga yo'naltiring
    • Boshqa oila a'zolariga o'zlarining sog'lig'i haqida qaror qabul qilishlariga yordam beradigan muhim ma'lumotlarni taqdim eting, masalan, ular ham variantni meros qilib olganligini aniqlash uchun genetik testdan o'tish kerakmi.

    Shuningdek, test natijalari ijobiy bo'lib, kelajakda saraton kasalligiga chalinish xavfi yuqori ekanligini ko'rsatadigan odamlar saraton kasalligini rivojlanish xavfini kamaytirish yoki saratonni erta aniqlash uchun choralar ko'rishlari mumkin, jumladan:

    • Yoshroq yoki tez-tez saraton belgilari uchun tekshiriladi
    • Dori-darmonlarni qabul qilish yoki "xavf ostidagi" to'qimalarni olib tashlash uchun operatsiya qilish orqali saraton xavfini kamaytirish. (Xavfni kamaytirishga qaratilgan bu yondashuvlar faqat bir nechta irsiy saraton sindromlari uchun variantlardir.)
    • Ba'zi saraton kasalliklari xavfini kamaytirish uchun shaxsiy xatti-harakatlarni o'zgartirish (masalan, chekishni tashlash, ko'proq harakat qilish va sog'lom ovqatlanish)
    • Fertillik va homiladorlik haqida qaror qabul qilish uchun yordam olish

    Salbiy natija. Sinov natijasining salbiy bo'lishi, laboratoriya test aniqlash uchun mo'ljallangan o'ziga xos variantni topa olmaganligini anglatadi. Bu natija oilada ma'lum bir kasallik qo'zg'atuvchi variant mavjudligi ma'lum bo'lganda foydali bo'ladi. Bunday holatda, salbiy natija, sinovdan o'tgan oila a'zosi o'z oilasida mavjud bo'lgan variantni meros qilib olmaganligini va shuning uchun bu odamda irsiy saratonga moyillik sindromi yo'qligini ko'rsatishi mumkin. Bunday test natijasi a deb ataladi haqiqiy salbiy. Haqiqiy salbiy natija saraton xavfi yo'qligini anglatmaydi, balki bu xavf umumiy populyatsiyadagi saraton xavfi bilan bir xil bo'ladi.

    Agar odamda kuchli oilada saraton kasalligi bo'lsa, lekin oilada irsiy saraton sindromi bilan bog'liq ma'lum variant topilmasa, salbiy test natijasi shunday tasniflanadi. ma'lumotga ega bo'lmagan salbiy (ya'ni, u odatda foydali ma'lumot bermaydi).

    Sinov natijasi salbiy bo'lsa, shifokorlar va genetik maslahatchilar ushbu shaxsning shaxsiy va oilaviy tarixi va ularda bo'lishi mumkin bo'lgan boshqa xavf omillari asosida tegishli saraton skriningidan o'tishini ta'minlashi muhimdir. Genetik test salbiy bo'lsa ham, ba'zi odamlar saraton nazoratini kuchaytirishdan foyda ko'rishlari mumkin.

    Noaniq ahamiyatga ega variant. Agar genetik test ilgari saraton bilan bog'liq bo'lmagan o'zgarishlarni ko'rsatsa, odamning test natijasi noaniq ahamiyatga ega bo'lgan variantni yoki VUSni bildirishi mumkin. Ushbu natija noaniq deb talqin qilinishi mumkin, ya'ni ma'lumotlar ularning xavfini aniqlashga yordam bermaydi va odatda sog'liqni saqlash bo'yicha qarorlar qabul qilishda hisobga olinmaydi.

    Ba'zi gen variantlari qayta tasniflanishi mumkin, chunki tadqiqotchilar saraton bilan bog'liq variantlar haqida ko'proq bilib olishadi. Ko'pincha, dastlab noaniq ahamiyatga ega variantlar sifatida tasniflangan variantlar yaxshi (klinik jihatdan muhim emas) deb qayta tasniflanadi, ammo ba'zida VUS saraton xavfining ortishi bilan bog'liq bo'lishi mumkin. Shuning uchun, sinovdan o'tgan shaxs genetik tekshiruvni o'tkazgan provayder bilan aloqada bo'lishi, agar variant bo'yicha biron bir yangi ma'lumot o'rganilgan bo'lsa, yangilanishlarni olishini ta'minlashi muhimdir.

    Yaxshi variant. Agar test saraton kasalligi bo'lmagan odamlar orasida umumiy populyatsiyada uchraydigan genetik o'zgarishlarni aniqlasa, o'zgarish yaxshi variant deb ataladi. Har bir insonda kasallik xavfining ortishi bilan bog'liq bo'lmagan tez-tez uchraydigan benign variantlar mavjud.

    Genetik test natijalari sinov vaqtida mavjud bo'lgan eng yaxshi ilmiy ma'lumotlarga asoslanadi. Afsuski, hech qanday test 100% xatosiz bo'lmasa-da, ko'pchilik genetik testlar juda aniq. Shu bilan birga, eng aniq test natijalarini ta'minlash uchun obro'li sinov laboratoriyasini tanlay oladigan saraton genetikasi bo'yicha bilimdon provayder tomonidan genetik testni buyurtma qilish juda muhimdir.

    Insonning genetik test natijalariga kim kirish huquqiga ega?

    Tibbiy test natijalari odatda odamning tibbiy yozuvlariga kiritiladi, ayniqsa shifokor yoki boshqa tibbiy xizmat ko'rsatuvchi provayder testni buyurgan bo'lsa yoki test natijalari bo'yicha maslahat olgan bo'lsa. Shuning uchun, genetik tekshiruvni o'ylaydigan odamlar, agar ularning ish beruvchisi bemorning tibbiy sug'urtasini imtiyoz sifatida taqdim etsa, ularning natijalari tibbiy ma'lumotlariga qonuniy, qonuniy kirish huquqiga ega bo'lgan boshqa odamlar yoki tashkilotlarga, masalan, sug'urta kompaniyasi yoki ish beruvchiga ma'lum bo'lishi mumkinligini tushunishlari kerak.

    Biroq, agar tibbiy sug'urta kompaniyalari yoki ish beruvchilar saraton kabi kasallik xavfini oshiradigan gen variantiga ega bo'lganligi yoki kuchli oilaviy tarixga ega bo'lganligi sababli odamlarga boshqacha munosabatda bo'lgan taqdirda yuzaga keladigan genetik kamsitishning oldini olish uchun qonuniy himoya mavjud. saraton kabi kasallik.

    2008 yilda genetik ma'lumotni kamsitmaslik to'g'risidagi qonun (GINA) AQShning barcha aholisi uchun federal qonunga aylandi. GINA sog'liq sug'urtasi muvofiqligi yoki stavkalari va ishga joylashish uchun mosligini aniqlashda genetik ma'lumotlarga asoslangan kamsitishni taqiqlaydi. Biroq, GINA harbiy xizmatchilarni qamrab olmaydi va u hayot sug'urtasi, nogironlik sug'urtasi yoki uzoq muddatli parvarish sug'urtasiga taalluqli emas. Ba'zi shtatlarda ushbu kontekstlarda kamsitish ehtimolini ko'rib chiqadigan qo'shimcha genetik diskriminatsiya qonunchiligi mavjud.

    Bundan tashqari, insonning genetik ma'lumotlari salomatlik haqidagi ma'lumotlarning bir turi hisoblanganligi sababli, u 1996 yildagi "Sog'liqni saqlash ma'lumotlarini o'tkazish va javobgarlik to'g'risida"gi qonunning (HIPAA) Maxfiylik qoidalari bilan qamrab olingan. Maxfiylik qoidasi tibbiy xizmat ko'rsatuvchi provayderlar va boshqalardan tibbiy ma'lumotga ega bo'lishini talab qiladi. kirish sog'liqni saqlash ma'lumotlarining maxfiyligini himoya qiladi, sog'liqni saqlash yozuvlaridan foydalanish va tarqatish bo'yicha cheklovlarni belgilaydi va odamlarga o'zlarining sog'lig'iga oid ma'lumotlardan muayyan foydalanish va almashishni nazorat qilish huquqini beradi. Ko'pgina shtatlarda bemorlarning shaxsiy hayotini himoya qilish va genetik va boshqa sog'liq ma'lumotlarini chiqarishni cheklash uchun qonunlar mavjud. Milliy Inson Genomi Tadqiqot Institutining Genetika Diskriminatsiyasi sahifasi GINA, HIPAA va sug'urta yoki ish bilan bog'liq genetik kamsitish bilan bog'liq boshqa qonunlar haqida qo'shimcha ma'lumotlarga havolalarni o'z ichiga oladi.

    Saraton xavfini tekshirish uchun uyda yoki to'g'ridan-to'g'ri iste'molchiga genetik testlardan foydalanish mumkinmi?

    To'g'ridan-to'g'ri iste'molchiga (DTC) genetik test sifatida ham tanilgan uyda genetik testlarni taklif qiladigan kompaniyalar soni ortib bormoqda. Odamlar o'zlari tupurik yoki og'iz bo'shlig'ini yig'ib, namunani pochta orqali yuborishadi. Ular test natijalari haqida xavfsiz veb-saytda, pochta orqali yoki telefon orqali bilib olishadi.

    Odatda shifokor tomonidan buyuriladigan saraton xavfining genetik tekshiruvi saraton kasalligining yuqori yoki o'rtacha ortishi xavfi bilan bog'liq va irsiy saratonga moyillik sindromlari uchun javobgar bo'lgan irsiy genetik variantlarni tekshirishni o'z ichiga oladi. Aksincha, saraton xavfi uchun DTC genetik testi ko'pincha individual ravishda xavfning ozgina oshishi bilan bog'liq bo'lgan umumiy irsiy genetik variantlarni tahlil qilishni o'z ichiga oladi. Hatto birgalikda qo'shilsa ham, ma'lum bir saraton turi bilan bog'liq barcha ma'lum umumiy variantlar odamning saraton xavfining faqat kichik qismini tashkil qiladi. Ushbu keng tarqalgan variantlarga asoslangan genetik testlar hali bemorlarga va ularning yordam ko'rsatuvchilariga sog'liqni saqlash bo'yicha qarorlar qabul qilishda yordam berish uchun topilmagan va shuning uchun ular tavsiya etilgan klinik amaliyotning bir qismi emas.

    Hatto odamlarda irsiy saratonga moyillik sindromlari bilan bog'liq bo'lgan gen variantlari uchun DTC genetik testlari bo'lsa ham, DTC testidan foydalanishda potentsial xavf va kamchiliklar mavjud. Misol uchun, ba'zi DTC genetik testlari quyidagi variantlarni qidiradi BRCA1 va BRCA2 irsiy ko'krak va tuxumdon saratoni sindromi (HBOC) bilan bog'liq genlar. Biroq, bu sinov aniqlangan minglab variantlardan faqat uchtasini qidiradi. Shuning uchun, kimdir bunday test bilan salbiy natijaga olib kelishi mumkin, ammo baribir zararli bo'lishi mumkin BRCA1 yoki BRCA2 Ushbu testda aniqlanmagan gen varianti. Xususan, bilimli tibbiy xizmat ko'rsatuvchi provayder tomonidan genetik test natijalarini talqin qilish uchun eng to'g'ri genetik tekshiruv bo'yicha ko'rsatmalarsiz odamlar keraksiz tashvish yoki yolg'on ishonchni boshdan kechirishlari mumkin yoki ular to'liq bo'lmagan tibbiy davolanish yoki parvarishlash bo'yicha muhim qarorlar qabul qilishlari mumkin. ma `lumot.

    DTC genetik testi ham test natijalarining maxfiyligini ta'minlamaydi. Kompaniyalarning oshkor qilish siyosati har doim ham taqdim etilmaydi yoki ularni topish va tushunish qiyin bo'lishi mumkin. Bundan tashqari, DTC testini ta'minlovchi kompaniyalar mavjud davlat va federal maxfiylik qonunlari va qoidalariga bo'ysunmasligi mumkin. Odatda DTC genetik testini o'tkazmoqchi bo'lgan odamlarga obro'li kompaniyani tanlaganliklariga ishonch hosil qilishlari tavsiya etiladi (ya'ni, uning maxfiylik siyosatini to'liq va aniq ochib beradigan).

    AQSh Federal Savdo Komissiyasi (FTC) uyda genetik testlar haqida ma'lumot varag'iga ega bo'lib, unda bunday testni o'ylamoqchi bo'lgan odamlar uchun maslahatlar mavjud. FTC o'z missiyasining bir qismi sifatida reklamalarda sog'lig'iga oid noto'g'ri yoki noto'g'ri da'volar haqidagi shikoyatlarni tekshiradi.

    Milliy Sog'liqni saqlash institutlari qoshidagi Milliy tibbiyot kutubxonasining iste'molchilar salomatligi veb-saytida Genetika Bosh sahifa Reference DTC genetik testi haqida ma'lumotga ega.

    Irsiy saratonga moyillik sindromlari uchun genetik testning afzalliklari qanday?

    Inson ijobiy yoki salbiy natija olishidan qat'i nazar, genetik testning afzalliklari bo'lishi mumkin.

    • Axborot beruvchi salbiy test odamga zararli gen varianti meros bo'lib o'tmaganligi haqida xotirjamlik berishi mumkin.
    • Ijobiy test natijasi odamga saraton xavfini tushunish va ba'zi hollarda boshqarish imkoniyatini beradi.
    • Allaqachon saraton tashxisi qo'yilgan odamlar uchun genetik test natijalari ularga davolanish to'g'risida qaror qabul qilishda va boshqa saraton kasalliklari xavfini tushunishda yordam beradi.
    • Genetika tekshiruvi oila a'zolariga o'zlarining saraton xavfi haqida bilish imkoniyatini beradi.

    Irsiy saratonga moyillik sindromlari uchun genetik testning mumkin bo'lgan zararlari qanday?

    Genetika testi potentsial hissiy, ijtimoiy va moliyaviy zararlarga olib kelishi mumkin, jumladan:

    • Saraton xavfini oshiradigan genetik variant borligini bilish va bu topilmalarni qon qarindoshlari bilan baham ko'rish kerakmi yoki yo'qligini aniqlashning psixologik stressi
    • Noaniq ahamiyatga ega variant (VUS) haqidagi hisobot kabi ma'lumotga ega bo'lmagan test natijalari noaniqlikni oshiradi va natijalar aniqlanmaguncha stressni kuchaytirishi mumkin.
    • Omon qolgan odam oilaning boshqa a'zolarida mavjud bo'lgan zararli variant yo'qligini bilib, aybdor bo'ladi.
    • Sinovning o'zi va agar sug'urta qoplamagan bo'lsa, qo'shimcha nazorat sinovlari narxi
    • Maxfiylik va kamsitish muammolari
    • DTC yoki klinik genetik test tomonidan taqdim etilgan noto'g'ri yoki chalg'ituvchi ma'lumotlar

    Genetik testlar qanday tartibga solinadi?

    Sog'liqni saqlash bilan bog'liq testlarni, shu jumladan genetik testlarni o'tkazadigan AQSh laboratoriyalari Klinik Laboratoriyani Takomillashtirish (CLIA) dasturiga muvofiq tartibga solinadi. CLIA bo'yicha sertifikatlangan laboratoriyalar sinovlarning sifati, aniqligi va ishonchliligi bo'yicha federal standartlarga javob berishi kerak. Genetika tekshiruvini o'tkazadigan va natijalarni baham ko'radigan barcha laboratoriyalar CLIA sertifikatiga ega bo'lishi kerak. Biroq, CLIA sertifikati faqat tegishli laboratoriya sifat nazorati standartlariga rioya qilinayotganligini ko'rsatadi, bu laboratoriya tomonidan o'tkaziladigan genetik test tibbiy jihatdan foydali yoki to'g'ri talqin qilinishiga kafolat bermaydi. Milliy Inson genomi tadqiqot instituti Genetika testlarini tartibga solish sahifasida ko'proq ma'lumotga ega.

    Saraton kasalligi uchun genetik testni yaxshilash uchun qanday tadqiqotlar olib borilmoqda?

    Ba'zi saraton turlari xavfini oshiradigan genetik variantlarga ega bo'lgan odamlarda saratonni aniqlash, davolash va oldini olishning yaxshiroq usullarini topish bo'yicha tadqiqotlar davom etmoqda. Olimlar, shuningdek, odamda saraton xavfini oshiradigan qo'shimcha genetik o'zgarishlarni topish bo'yicha tadqiqotlar olib bormoqda. Sinov orqali aniqlangan genetik variantlarni tasniflashning aniqligi va izchilligini oshirish bo‘yicha ham ko‘p ishlar amalga oshirilmoqda.

    Tadqiqotning yana bir yo'nalishining maqsadi shifokorlar va bemorlarga o'ziga xos genetik variantlar, xususan, noaniq ahamiyatga ega variantlar bilan bog'liq saraton xavfi haqida yaxshiroq ma'lumot berishdir. Masalan, toʻyinganlik genomini tahrirlash deb ataladigan tadqiqot yondashuvlaridan biri CRISPR-Cas9 genini tahrirlashdan foydalanib, butun mintaqada 4000 xil genetik variantlarni yaratdi. BRCA1 o'simta bostirish funktsiyasi uchun muhim bo'lgan gen. Genni tahrirlash BRCA1 oqsilisiz omon qololmaydigan maxsus hujayralarda amalga oshirildi. Klinik ma'lumotlar mavjud bo'lgan variantlar uchun genlarni tahrirlash natijalari klinik topilmalar bilan 96% dan ko'prog'iga mos keldi va bu yondashuv boshqa genlardagi noaniq ahamiyatga ega variantlar bilan bog'liq saraton xavfini tasniflash uchun ishlatilishi mumkinligini ko'rsatadi.

    BRCA Exchange veb-portali kabi genomik va klinik ma'lumotlarni birlashtirgan hamkorlikdagi sa'y-harakatlar odamlar genetik test natijalarini olganlarida va ma'lum bir gen variantining klinik ahamiyatini bilmoqchi bo'lganlarida murojaat qilishlari mumkin bo'lgan keng qamrovli manbani taqdim etadi. ClinVar - bu genetik variantlarning klinik ahamiyati bo'yicha dalillar to'planishini qo'llab-quvvatlaydigan jamoat arxivi.

    NCI o'zining saraton genomikasi tadqiqot laboratoriyasi orqali genom bo'ylab assotsiatsiyalarni o'rganish bo'yicha faol dasturni (GWAS) boshqaradi. Ushbu usul ko'plab odamlarning genomlarini solishtiradi va muayyan kuzatiladigan xususiyatlar yoki kasallik xavfi bilan bog'liq genetik belgilarni topadi. Maqsad genlarning kasallikka qanday hissa qo'shishini tushunish va bu tushunchadan yaxshiroq oldini olish va davolash strategiyalarini ishlab chiqishda foydalanish.

    Qo'shimcha NCI tadqiqotlari genetik maslahat usullari va natijalarini takomillashtirishga, uyda genetik testning xavflari va afzalliklarini o'rganishga va ushbu testlarni reklama qilishning bemorlarga, provayderlarga va sog'liqni saqlash tizimiga ta'sirini baholashga qaratilgan. Tadqiqotchilar, shuningdek, genetik tekshiruv uchun mavjud laboratoriya usullarini takomillashtirish ustida ishlamoqda.

    Tanlangan havolalar

    Findlay GM, Daza RM, Martin B va boshqalar. To'yinganlik genomini tahrirlash bilan BRCA1 variantlarining aniq tasnifi. Tabiat 2018 562(7726):217-222.

    Garber J, Offit K. Irsiy saratonga moyillik sindromlari. Klinik Onkologiya jurnali 2005 23(2):276–292.

    Hampel H, Bennett RL, Buchanan A va boshqalar. Amerika Tibbiyot Genetika va Genomika Kolleji va Milliy Genetika Maslahatchilar Jamiyatining amaliy qo'llanmasi: saratonga moyilligini baholash uchun tavsiyanomalar. Tibbiyotda genetika 2015 17(1):70-87.

    Lindor NM, McMaster ML, Lindor CJ, Greene MH. Oilaviy saratonga moyillik sindromlari bo'yicha qisqacha qo'llanma - ikkinchi nashr. Milliy saraton instituti monografiyalari jurnali 2008 38:1–93.

    McGee RB, Nikols KE. Saratonning genetik sezuvchanlik sindromlari bilan tanishish. Gematologiya / Amerika Gematologiya Jamiyatining Ta'lim Dasturi 2016 2016(1):293-301.

    Mersch J, Braun N, Pirzadeh-Miller S va boshqalar. Irsiy saraton genetik testidan so'ng variantni qayta tasniflashning tarqalishi. JAMA 2018 320(12):1266-1274.

    Riley BD, Culver JO, Skrzynia C va boshqalar. Genetik saraton xavfini baholash, maslahat berish va sinovdan o'tkazishning asosiy elementlari: Milliy genetik maslahatchilar jamiyatining yangilangan tavsiyalari. Genetika maslahati jurnali 2012 21(2):151–161.

    Robson M, Storm C, Weitzel J va boshqalar. Amerika Klinik Onkologiya Jamiyati siyosati bayonoti yangilanishi: Saratonga moyillik uchun genetik va genomik testlar. Klinik Onkologiya jurnali 2010 28(5):893–901.

    Spenser DH, Lockwood C, Topol E va boshqalar. To'g'ridan-to'g'ri iste'molchiga genetik test: ishonchli yoki xavfli? Klinik kimyo 2011 57(12): 1641–1644.


    Odamlarda parazitar infektsiya: omillar va misollar | Biologiya

    Ushbu maqolada biz quyidagilarni muhokama qilamiz:- 1. Parazitar infektsiyaning umumiy xususiyatlari 2. Parazitar infektsiya va kasalliklardan o'tishga ta'sir qiluvchi omillar 3. Misollar.

    Parazitar infektsiyaning xususiyatlari:

    Ba'zi parazitlar (ektoparazitlar) uy egasining yuzasida, boshqalari (endoparazitlar) esa uy egasi ichida yashaydi. Ba'zi ektoparazitlar o'z-o'zidan kasallik qo'zg'atuvchisi (masalan, qo'tir oqadilar) yoki infektsiya tashuvchisi (masalan, vabo tayoqchasini, Yersinia pestisni yuboruvchi burgalar) sifatida muhimdir.

    Biroq, umuman olganda, endoparazitlar parazit va xost o'rtasidagi yaqin aloqaning ancha yuqori darajasi tufayli kasallikning sabablari sifatida potentsial darajada muhimroqdir. (Ekstremal misol bezgak paraziti bo'lib, u o'z tsiklining bir qismi uchun odamlarning eritrotsitlari ichida yashaydi.)

    Qayerda va qaysi guruhdagi odamlarda parazitar infektsiya ko'proq sodir bo'lishi ko'p jihatdan atrof-muhit sharoitlari (uy-joy, suv ta'minoti va kanalizatsiya) va iqlim (ayniqsa, yog'ingarchilik va harorat) bilan belgilanadi. INFEKTSION tez-tez uchraydigan joylarda ham, odamlar infektsiyaga duchor bo'lish darajasida farqlanadi, shaxsiy himoya yoki shaxsiy gigiena kabi omillar ayniqsa muhimdir.

    Parazitar infektsiyalar tropik va subtropiklarning ‘rivojlanayotgan’ jamoalarida eng keng tarqalgan bo'lsa-da, ular sharoitlar mos bo'lgan joyda paydo bo'lishi mumkin. Bundan tashqari, odamlar bir vaqtning o'zida bir nechta parazitlarni yuqtirishlari mumkin va bu, ayniqsa, bir qator parazitlar umumiy yo'l bilan (masalan, najas-og'iz yo'li) yuqadigan joylarda.

    Factors Affecting the Shift from Parasitic Infection and Diseases:

    In the individual, the balance between parasitic infection and disease can be affected by a number of factors acting either independently or in concert. The inner-relationships between host and parasites are complex and are grouped under three broad headings: host-related parasite-related and immunological.

    i. Host-Related Factors:

    Children upto to about 6 months old are rarely susceptible to parasitic infection because of the protection afforded by maternal antibodies and also because of a significantly lower risk of exposure to infection.

    After about 6 months, a child is exposed to a wide variety of infectious agents and the prevalence and severity of infections rise dramatically, reaching a peak in the age group 6 months to 5 years. While older people may continue to be at risk of infection, the degree of exposure, the intensity of infection and the occurrence of disease are often lower.

    Malnourishment is important in shifting the balance from infection towards disease, a malnourished person being much less able to withstand the adverse effects of disease. This is a particular problem in the ‘developing’ world where malnutrition is common.

    ii. Parasite-Related Factors:

    Parasite-related factors include the physical size and/or number of parasites, their site of occurrence, their rate of multiplication, their metabolism, and differences in pathogenicity shown by different parasite strains.

    Parasites which grow to a large physical size or multiply rapidly have a much greater potential for causing disease than those which are small or multiply slowly. Many protozoan parasites, such as Plasmodium spp. (malarial parasites), and those which live in the intestine, are capable of very rapid asexual multiplication so that they make up in numbers what they may lack in individual size. Thus, it is perhaps more meaningful to consider biomass rather than physical size as the important factor.

    b. Multiplication Rates:

    Inherent differences in the rate of multiplication between closely related parasites are also important. P. falciparum has a considerably faster rate of multiplication than the other three species of malarial parasite affecting humans and this contributes substantially to the greater severity of the disease it causes.

    Another factor related to the rate of multiplication is the size of the infective dose necessary to establish an infection. The minimum infective dose for Giardia lamblia may be as low as 10 cysts whereas that for Entamoeba histolytica may be in the region of several thousand cysts.

    d. Site of Occurrence:

    Site of occurrence is particularly important in determining whether infection shifts towards disease. For example, parasites in the intestine of an otherwise healthy individual generally cause little or no disease unless they become invasive (such as some strains of Entamoeba histolytica), multiply rapidly (such as Giardia lamblia) or migrate to inappropriate sites (such as adult Ascaris lumbricoides in the bile or pancreatic duct).

    Parasites which have stages in the tissues or which become tissue invaders are generally more pathogenic than those which live in the intestine. This is because parasites in the tissues have more intimate contact with the body than those in the intestine, where parasites and their products (including metabolic products and eggs) are carried away in the gut contents and faeces.

    While most parasites have a ‘normal’ site of occurrence in the body where they may or may not cause disease, some parasites may occasionally be found in appropriate sites where their effects can be much more serious. For instance, during its development, the human lung fluke, Paragonimus westermanii, migrates from the intestine through the diaphragm to the lungs where it produces eggs.

    Normally, these eggs pass harmlessly out of the body in sputum, causing no ill effects to the host. However, occasionally some immature worms migrate to other body sites where they lay eggs. These eggs are unable to escape and a granuloma develops round them. If this occurs in the central nervous system, the consequences for the patient are quite different from the more typical lung infection.

    e. Parasite Metabolism:

    By definition, the parasite depends on the host for its nutrition and therefore the host is deprived (to a greater or lesser extent) of material which it could otherwise use for its own metabolic purposes.

    Severe infection with some intestinal parasites (such as hookworm) can exacerbate an already poor nutritional state, even to the point where it becomes life-threatening. A second aspect is the effect that some parasite metabolites have on the host. The intra-erythrocytic stages of the malarial parasite metabolize haemoglobin in the infected red cell.

    When the red cell bursts, the products of this metabolism are released into the general circulation and provoke the characteristic malaria fever. The fever is itself an important part of the chain of events leading to severe illness or death in the untreated patient.

    f. Strain Differences:

    It is well known that some strains of parasite are potentially more pathogenic than others. Infection with Entamoeba histolytica acquired in the tropics is much more likely to cause disease than infections acquired elsewhere.

    iii. Immunological Factors:

    Although parasitic infections may stimulate the production of antibodies, in most cases these antibodies are not protective although they may be useful as indicator of existing, or of relatively recent, infection. Most anti-parasite antibodies persist for some time after successful treatment and, in general, antibody tests are of little value as tests of cure.

    A marked feature of the immune reaction to helminthic infections is the high level of immunoglobulin E (IgE) antibody produced. Various roles are attributed to IgE in protective responses to parasitic infections including release of mast cells secretory products.

    The effectiveness of an individual’s immune response to a parasitic infection may be affected by a number of factors, including those outlined below:

    i. Other infections (such as measles, which is particularly common in ‘developing’ countries) can lower the host’s resistance to, or tolerance of, parasitic infection and permit opportunist infections to develop.

    ii. Pregnancy lowers the mother’s general resistance to infection and a parasitic infection which has been in a state of equilibrium may become life-threatening during pregnancy.

    iii. Inherited or acquired immunodeficiency may substantially lower an individual’s immunity to a parasitic infection. This is well illustrated in the case of HIV infection and AIDS where affected individuals are more prone to a range of infections including those caused by parasites.

    iv. Immunosuppressant drugs may have a similarly dramatic effect on an existing (and perhaps unsuspected) parasitic infection.

    There are two other aspects of immunological relationship between the parasite and the host that are important. These are the host’s response to antigens of the parasite and the parasite’s response to host immunity.

    Much of the pathology caused by heavy infection with schistosome parasites results from the host’s reaction to metabolites produced by the small proportion of eggs laid by the female worms which become trapped in the tissue (around 95 percent of eggs pass out in the urine or faeces).

    The host response is initially in the form of a giant cell reaction followed by progressive fibrosis, the formation of a granuloma round each egg (the final lesion being several times the volume of the egg that provoked it) and the replacement of normal tissue by these granulomas. The fibrous reaction associated with heavy infection of Schistosoma mansoni can cause constriction of the hepatic portal circulation leading to enlargement of the liver and spleen (hepato-splenomegaly).

    Some species of parasite are able to avoid or to counteract the effects of host immunity. Some parasites are able to survive within macrophages and so are sheltered from any immune response. To do this they must block the normal microbiocidal mechanisms of the macrophage. Toxoplasma gondii, for example, inhibits phagosome-lysosome fusion, whereas Leishmania spp. are surrounded by a dense coat which can protect them from the oxidative burst.

    During the early stages of their migration through the host, schistosome parasites incorporate host material into their outermost layers, effectively camouflaging their identity and preventing the host immune system from recognizing and destroying them.

    On the other hand, trypanosomes causing African sleeping sickness provoke an immunological response by the host which is potentially fatal to the parasites. However, these organisms are able to evade this immune response by producing broods of antigenically different parasites in quick succession. The host’s immune response never quite catches up with these frequent changes in antigenicity and the parasites are able to survive.

    Examples of Parasitic Infection:

    The following examples are intended to illustrate some of the general principles of parasitic infection discussed above:

    Entamoeba histolytica infections occur throughout the world and account for the third most common cause of death from parasitic disease. Infection is particularly common in warm, moist environments and where sanitation is poor.

    Transmission is faecal-oral and the parasites are normally found in the lumen of the large intestine feeding on food particles. The parasites become invasive in less than 20 percent of infections, lesions usually starting in the large intestine as small discrete, button ­like ulcers.

    The advancing ulcer becomes flask-shaped, eventually extending through all layers of the gut wall. Amoebae may be carried in the blood to other parts of the body where an abscess may develop. The liver (particularly the right lobe) is most frequently affected. The liver abscess is usually single but may be multiple, does not have a well-defined wall and is usually bacteriologically sterile.

    Liver abscess is about 10 times more frequent in adults than in children and about five times more common in males than in females, but the degree to which differences in exposure are responsible for these variations is not clear.

    Malnourishment may increase the severity of infection and immunodeficiency may elicit or worsen the clinical effects of infection. Asymptomatic female carriers may develop severe amoebiasis during pregnancy and the puerperium.

    The four species of malaria parasites which infect humans are P. falciparum, P. vivax, P. ovale and P. malariae. The infective stage (sporozoites) are inoculated by an infected female mosquito during a blood meal and subsequently invade and develop inside hepatocytes. Each parasites multiplies asexually as a liver schizont, producing (according to species) between 10-40000 merozoites.

    When the mature liver schizont bursts, the merozoites are released. They invade the erythrocytes, mature to trophozoites (ring forms) and then begin another cycle of asexual multiplication as erythrocytic schizonts. Each erythrocytic schizont contains, at maturity, between about eight and 24 merozoites. When mature, the erythrocytic schizont bursts, releasing the merozoites which invade other the cycle repeating itself every 36-72 hours according to the species.

    The four species differ in their degreee of pathogenicity. P. falciparum is the most pathogenic because it produces more merozoites in both liver and erythrocytic schizont stages, invades red cells of all ages, and has the shortest schizogancy cycle in the blood. Numbers of P. falciparum organisms in the blood can rapidly reach life-threatening levels. Although the other three species can cause severe disease, their parasitamias are rarely life-threatening.

    The disease process in malaria is complex. The liver stages have no effect on the individual but illness results directly or indirectly from the destruction of erythrocytes, the number destroyed increasing progressively with each schizogany cycle.

    The regular destruction of red cells results in increasing anaemia, while the release of parasite metabolites causes fever which can itself have serious consequences if severe (when the erythrocytic schizogany cycle is well synchronized, the fever pattern may become sufficiently regular to be characteristic of the species).

    Blockage of the capillaries by the erythrocytic schizonts (especially those of P. falciparum) leads to tissue anoxia and cell death. The kidneys, digestive and respiratory systems can all be affected, with accompanying renal failure, vomitting and diarrhoea. When capillary blockage occurs in the brain, cerebral malaria, coma and death result, unless treatment is initiated as an emergency.

    iii. Hydatid disease:

    The adult tapeworms, Echinococcus granulosus, live in the intestine of dogs and other carnivores. Eggs are passed in the faeces of the dog and the larval stages from so-called ‘hydatid cysts’ (cysts of varying sizes composed of developing larvae) in infected sheep and other herbivores. Dogs become infected when they eat carcasses or offal containing the hydatid cysts.

    Human infection occurs in areas where there is a close association between sheep, sheep dogs and humans and results from the accidental ingestion of Echinococcus eggs. The eggs hatch in the intestine and the larvae bore their way into the gut wall and are carried around the body in the bloodstream before developing into the hydatid cyst. The usual site is the live but they can lodge in other parts of the body such as the bone marrow or brain.

    As the hydatid cyst can grow to 100 mm or more in diameter its physical size can have serious effect on the organ in which it occurs. The fluid in the centre of the cyst is also highly allergenic and if the cyst burts (or is ruptured during surgical removal) the patient may well suffer a severe and possibly fata anaphylactic reaction.

    Although all age groups are susceptible to infection by Ascaris lumbricoides, children between the ages of about 1 and 5 years have the highest prevalence and intensity of infection (children living in poor environmental conditions may harbour more than 100 worms).

    Adult worms are large (females measure up to about 35 cm in length and males up to about 20 cm), physically strong and normally live in the lumen of the small intestine. Provided the worms remain in the lumen of the intestine, light infections in a well-nourished person cause little or no problem. About 85 percent of infections are asymptomatic.

    Obstruction of the intestine occurs more frequently in heavy infections and can be surgical emergency—in some part of the world more than 50 percent of children admitted to hospital with acute abdominal conditions suffer from ascariasis. Single worms occasionally migrate into and obstruct the bile or pancreatic duct, and the passage of relatively large numbers of larvae through the lungs at any one time causes a pneumonitis (lung inflammation) lasting a few days.


    Epidemiologiya va xavf omillari

    Human scabies is caused by an infestation of the skin by the human itch mite (Sarcoptes scabiei var. hominis). The adult female scabies mites burrow into the upper layer of the skin (epidermis) where they live and deposit their eggs. The microscopic scabies mite almost always is passed by direct, prolonged, skin-to-skin contact with a person who already is infested. An infested person can spread scabies even if he or she has no symptoms. Humans are the source of infestation animals do not spread human scabies.

    Persons At Risk

    Scabies can be passed easily by an infested person to his or her household members and sexual partners. Scabies in adults frequently is sexually acquired.

    Scabies is a common condition found worldwide it affects people of all races and social classes. Scabies can spread easily under crowded conditions where close body and skin contact is common. Institutions such as nursing homes, extended-care facilities, and prisons are often sites of scabies outbreaks. Child care facilities also are a common site of scabies infestations.

    Crusted (Norwegian) Scabies

    Some immunocompromised, elderly, disabled, or debilitated persons are at risk for a severe form of scabies called crusted, or Norwegian, scabies. Persons with crusted scabies have thick crusts of skin that contain large numbers of scabies mites and eggs. The mites in crusted scabies are not more virulent than in non-crusted scabies however, they are much more numerous (up to 2 million per patient). Because they are infested with such large numbers of mites, persons with crusted scabies are very contagious to other persons. In addition to spreading scabies through brief direct skin-to-skin contact, persons with crusted scabies can transmit scabies indirectly by shedding mites that contaminate items such as their clothing, bedding, and furniture. Persons with crusted scabies should receive quick and aggressive medical treatment for their infestation to prevent outbreaks of scabies.


    Natijalar

    The median age of the study cohort at the time of HCT was 40 years (range, 0.6-71 years). Of the 2941 patients, 1927 (66%) received bone marrow, 1284 (44%) had HLA-matched related donors, 780 (26%) had HLA-matched unrelated donors, and 877 (30%) had HLA-mismatched related or unrelated donors. Other demographic characteristics of the cohort are summarized in Table 1.

    Characteristics of the study cohort

    Characteristic . Value .
    No. of patients 2941
    Median age (range), y 40.3 (0.6-71.6)
    Diagnosis at transplantation, no. (%)
    Acute myeloid leukemia 859 (29)
    Acute lymphoid leukemia 419 (14)
    Chronic myeloid leukemia 895 (30)
    Myelodysplastic syndromes including myeloproliferative diseases 504 (17)
    Chronic lymphocytic leukemia and lymphomas 191 (7)
    Multiple myeloma 73 (2)
    Disease at transplantation, no. (%)*
    Low risk 646 (22)
    Standard risk 1419 (48)
    High risk 877 (30)
    Donor age, median (range), y38.6 (0.9-81.7)
    Donor/patient sex, no. (%)
    Female/male 722 (25)
    Boshqa 2219 (75)
    High-intensity conditioning regimens, no. (%)
    With TBI 1730 (59)
    Without TBI 1137 (39)
    With rabbit ATG 74 (3)
    GVHD prophylaxis, no. (%)
    Methotrexate with calcineurin inhibitors 2394 (81)
    Boshqa 547 (19)
    Graft source, no. (%)
    Mobilized blood hematopoietic stem cells 1014 (34)
    Bone marrow 1927 (66)
    Donor type, no. (%)
    HLA-identical related 1284 (44)
    HLA-matched unrelated 780 (26)
    HLA-mismatched related 270 (9)
    HLA-mismatched unrelated 607 (21)
    Characteristic . Value .
    No. of patients 2941
    Median age (range), y 40.3 (0.6-71.6)
    Diagnosis at transplantation, no. (%)
    Acute myeloid leukemia 859 (29)
    Acute lymphoid leukemia 419 (14)
    Chronic myeloid leukemia 895 (30)
    Myelodysplastic syndromes including myeloproliferative diseases 504 (17)
    Chronic lymphocytic leukemia and lymphomas 191 (7)
    Multiple myeloma 73 (2)
    Disease at transplantation, no. (%)*
    Low risk 646 (22)
    Standard risk 1419 (48)
    High risk 877 (30)
    Donor age, median (range), y38.6 (0.9-81.7)
    Donor/patient sex, no. (%)
    Female/male 722 (25)
    Boshqa 2219 (75)
    High-intensity conditioning regimens, no. (%)
    With TBI 1730 (59)
    Without TBI 1137 (39)
    With rabbit ATG 74 (3)
    GVHD prophylaxis, no. (%)
    Methotrexate with calcineurin inhibitors 2394 (81)
    Boshqa 547 (19)
    Graft source, no. (%)
    Mobilized blood hematopoietic stem cells 1014 (34)
    Bone marrow 1927 (66)
    Donor type, no. (%)
    HLA-identical related 1284 (44)
    HLA-matched unrelated 780 (26)
    HLA-mismatched related 270 (9)
    HLA-mismatched unrelated 607 (21)

    Low-risk diseases included CML in chronic phase high-risk diseases included acute leukemia not in remission, CML in blast crisis, refractory anemia with excess blasts (RAEB), or RAEB in transformation and myeloma all other diseases and stages were categorized as standard risk.

    Cumulative incidence estimates of acute grades 2-4 GVHD and NIH chronic GVHD

    The cumulative incidence of grades 2-4 acute GVHD at 6 months was 80% (95% CI, 78%-81%), including patients with isolated upper gastrointestinal GVHD 27 (Figure 1 top panel). The 2-year cumulative incidence of NIH chronic GVHD treated with systemic immunosuppression was 34% (95% CI, 32%-35% Figure 1 bottom panel). Of the 2941 patients in our study, 461 (16%) did not develop either acute GVHD or NIH chronic GVHD. In the entire cohort, 1433 (48.7%) patients had acute GVHD without NIH chronic GVHD, 100 (3.4%) had NIH chronic GVHD without acute GVHD, and 922 (31.3%) had both acute GVHD and NIH chronic GVHD. Among these 922 patients, 840 (91%) had acute GVHD before NIH chronic GVHD, 77 (8%) developed de novo NIH overlap syndrome, and 5 (0.5%) patients with de novo NIH classic chronic GVHD subsequently developed NIH overlap syndrome. The median time from HCT to onset of acute grades 2-4 GVHD was 20 (range, 3-711) days. The median time from HCT to onset of NIH chronic GVHD was 162 (range, 66-2805) days.

    Cumulative incidence of grades 2-4 acute GVHD (top panel) and NIH chronic GVHD (bottom panel).

    Cumulative incidence of grades 2-4 acute GVHD (top panel) and NIH chronic GVHD (bottom panel).

    Risk factors for the development of grades 2-4 acute GVHD

    As shown in Figure 2, the multivariate analysis identified 4 factors strongly associated with an increased risk of grades 2-4 acute GVHD with P < .001. These risk factors included HCT with HLA-matched unrelated donors (HR, 1.66 95% CI, 1.48-1.85), HCT with HLA-mismatched related donors (HR 1.74 95% CI, 1.49-2.03), HCT with HLA-mismatched unrelated donors (HR, 2.00 95% CI, 1.78-2.25), all compared with HCT with HLA-matched related donors, and the use of TBI in the conditioning regimen (HR 1.49 95% CI, 1.27-1.54) compared with no TBI in the conditioning regimen. The use of a female donor for a male recipient was also associated with an increased risk of grades 2-4 acute GVHD, (HR, 1.14 95% CI, 1.04-1.25 P = .006). The 2 factors associated with a decreased risk of grades 2-4 acute GVHD were the use of rabbit ATG in the pretransplantation conditioning regimen (HR 0.77 95% CI, 0.58-1.03 P = .08) and diagnosis of CML (HR, 0.87 95% CI, 0.79-0.95 P = .003). Grafting with growth factor–mobilized blood cells and patient and donor age showed no statistically significant associations with risk of grades 2-4 acute GVHD (Figure 2).

    Multivariate risk factor profiles for grades 2-4 acute GVHD and NIH chronic GVHD. Hazard ratio and 95% CI for each risk factor are shown. The analysis included 2355 grades 2-4 acute GVHD events and 1022 NIH chronic GVHD events. Hazard ratios are relative to patients without the risk factor.

    Multivariate risk factor profiles for grades 2-4 acute GVHD and NIH chronic GVHD. Hazard ratio and 95% CI for each risk factor are shown. The analysis included 2355 grades 2-4 acute GVHD events and 1022 NIH chronic GVHD events. Hazard ratios are relative to patients without the risk factor.

    Risk factors for development of NIH chronic GVHD treated with systemic immunosuppression

    Seven factors showed statistically significant associations with an increased risk of NIH chronic GVHD (Figure 2 and Table 2): HCT with HLA-matched unrelated donors (P < .001), HCT with HLA-mismatched related donors (P = .05), HCT with HLA-mismatched unrelated donors (P < .001), all compared with HCT with HLA-matched related donors, the use of a female donor for a male recipient (P < .001), grafting with mobilized blood cells (P < .001), and older donor and recipient age (P = .006 and < .001, respectively). As shown in Figure 2, 2 factors associated with a decreased risk of NIH chronic GVHD were the use of rabbit ATG in the pretransplant conditioning regimen (P = .06) and a diagnosis of CML (P = .04).

    Multivariate analysis of risk factors for NIH chronic GVHD before and after adjustment for acute GVHD

    Risk factor . Adjustment for acute GVHD,* HR (95% CI) .
    No . Yes .
    Unrelated donor 1.35 (1.14-1.59) 1.30 (1.10-1.54)
    HLA-mismatched related donor 1.30 (1.01-1.68) 1.24 (0.95-1.60)
    HLA-mismatched unrelated donor 1.76 (1.47-2.11) 1.67 (1.39-2.00)
    Female donor for male patient 1.38 (1.21-1.59) 1.37 (1.19-1.57)
    Mobilized blood cell grafts 1.74 (1.45-2.08) 1.74 (1.46-2.08)
    Diagnosis of CML 0.86 (0.75-1.00) 0.88 (0.77-1.02)
    Conditioning with TBI 1.11 (0.96-1.28) 1.07 (0.92-1.34)
    Conditioning with ATG 0.68 (0.45-1.02) 0.70 (0.47-1.06)
    Patient age per decade 1.13 (1.07-1.19) 1.13 (1.07-1.19)
    Donor age per decade 1.09 (1.03-1.16) 1.09 (1.02-1.15)
    Acute GVHD grade
    1 yo'q 0.90 (0.62-1.30)
    2 yo'q 1.14 (0.95-1.37)
    3-4 yo'q 1.42 (1.14-1.77)
    Risk factor . Adjustment for acute GVHD,* HR (95% CI) .
    No . Yes .
    Unrelated donor 1.35 (1.14-1.59) 1.30 (1.10-1.54)
    HLA-mismatched related donor 1.30 (1.01-1.68) 1.24 (0.95-1.60)
    HLA-mismatched unrelated donor 1.76 (1.47-2.11) 1.67 (1.39-2.00)
    Female donor for male patient 1.38 (1.21-1.59) 1.37 (1.19-1.57)
    Mobilized blood cell grafts 1.74 (1.45-2.08) 1.74 (1.46-2.08)
    Diagnosis of CML 0.86 (0.75-1.00) 0.88 (0.77-1.02)
    Conditioning with TBI 1.11 (0.96-1.28) 1.07 (0.92-1.34)
    Conditioning with ATG 0.68 (0.45-1.02) 0.70 (0.47-1.06)
    Patient age per decade 1.13 (1.07-1.19) 1.13 (1.07-1.19)
    Donor age per decade 1.09 (1.03-1.16) 1.09 (1.02-1.15)
    Acute GVHD grade
    1 yo'q 0.90 (0.62-1.30)
    2 yo'q 1.14 (0.95-1.37)
    3-4 yo'q 1.42 (1.14-1.77)

    HR indicates hazard ratio and n/a, not applicable.

    HRs are relative to patients without the risk factor.

    A separate analysis was carried out to assess the association of acute GVHD with risk of NIH chronic GVHD. When acute GVHD was evaluated as a time-dependent covariate with no adjustment for the risk factors listed in the left column of Table 2, results showed no statistically significant association of grade 1 (HR, 0.90 95% CI, 0.62-1.30) or grade 2 (HR, 1.14 95% CI, 0.95-1.37) acute GVHD with risk of NIH chronic GVHD. Grades 3-4 acute GVHD, however, showed a statistically significant association with an increased risk of NIH chronic GVHD (HR, 1.42 95% CI, 1.14-1.77).

    Table 2 compares risk factors for NIH chronic GVHD before and after adjustment for prior acute GVHD. Adjustment for prior acute GVHD produced little change in the hazard ratio point estimates and 95% confidence intervals for the association of other risk factors with NIH chronic GVHD. The absence of major change in the model indicates that the association of risk factors with NIH chronic GVHD is independent of their association with acute GVHD.

    Comparison of risk factors for acute GVHD and NIH chronic GVHD

    Whereas the overall profiles of risk factors for grades 2-4 acute GVHD and NIH chronic GVHD were similar, we found some notable differences (Figure 2). Recipient HLA mismatching and grafts from unrelated donors had a greater effect on the risk of acute GVHD compared with the effect on NIH chronic GVHD, whereas the use of a female donor for a male recipient had a greater effect on the risk of NIH chronic GVHD compared with the effect on the risk of acute GVHD. Our analysis identified 3 discordant associations with acute GVHD and NIH chronic GVHD: (1) the use of a mobilized blood cell graft was associated with an increased risk of NIH chronic GVHD but had no statistically significant association with the risk of acute GVHD (2) the use of TBI in the conditioning regimen was associated with an increased risk of acute GVHD but had no statistically significant association with the risk of NIH chronic GVHD and (3) older patient age was associated with an increased risk of NIH chronic GVHD and with a trend suggesting a slightly decreased risk of acute GVHD.


    This article has been peer reviewed.

    Raqobatli manfaatlar: Piush Mandhane has received speaker’s honoraria from Merck Canada and the Edmonton Thoracic Society. None declared for Padmaja Subbarao and Malcolm Sears.

    Contributors: All authors contributed to the development and editing of the publication, and all approved the final version submitted for publication.

    Moliyalashtirish: The Canadian Thoracic Society has received funding to facilitate the knowledge translation activities of the CTS Asthma Committee from AstraZeneca Canada, GlaxoSmithKline Inc., Merck Frosst Canada and Novartis Pharmaceuticals. None of the sponsors played a role in the collection, review, analysis or interpretation of the scientific literature or in any decisions regarding the key messages presented in the case studies.


    Challenges in Research on Causes of Cancer

    Demonstrating cause-and-effect relationships in population studies examining potential cancer risk factors is a challenge because there are often many possible explanations for observed associations between a risk factor and cancer. Rare cancers and uncommon exposures, in particular, present challenges for researchers studying the causes of cancer. New statistical methods may be needed to improve the analysis of datasets of all sizes from these studies.

    When studying certain exposures, such as dietary exposures, identifying which component is associated with an increased or decreased risk of cancer can also be a challenge. Retrospective studies have additional limitations, such as participants’ inability to accurately remember and report past exposures or exposure levels.

    There is a continual need for new and improved techniques for measuring risk factors and exposures to potential causes of cancer. For example, studies that estimate radiation exposures among an exposed population must also quantify the uncertainties inherent to those estimates.

    To identify cancer causes and risk factors that may be experienced by only a portion of the population, very large studies may be needed to have the statistical power required to establish an association.

    Investigating interactions between genes and environmental exposures that have been associated with cancer is a challenge because some of these studies involve enormous data sets and require sophisticated computational analyses. Once a causative agent has been identified, another challenge is figuring out how to reduce a person’s exposure or ameliorate its harmful effects.

    Although genome-wide association studies can point to chromosomal regions associated with cancer risk in certain populations, additional studies and analyses are needed to identify the specific genetic changes involved and to understand how they play a role in the development of cancer.


    Lifestyle Factors

    Malaria is an infection that is predominantly spread in certain geographic regions with a tropical climate and an abundance of still water, where the mosquito vector that carries the parasite can survive. Lifestyle factors can play a role in whether or not you are likely to become infected with the parasite.

    Living in a Region With a High Rate of Malaria

    Living in a region that is known for malaria substantially increases the risk of becoming infected. -

    While it has been noted that some people living in regions with a high rate of malaria may become immune, many otherwise healthy people with normal immune systems experience serious complications and may die from the infection.

    Visiting a Region With a High Rate of Malaria

    Travelers who visit regions with a high rate of malaria may become infected, particularly because travelers who have not been exposed to the infection before have not developed immunity to the condition.

    Environmental Factors

    Some factors increase exposure to malaria, including a lack of protective clothing, exposed sleeping accommodations, lack of insect repellant, and lack of immunization. Especially when traveling, do your best to take proper precautions.


    Infectious agents and neurodegeneration

    A growing body of epidemiologic and experimental data point to chronic bacterial and viral infections as possible risk factors for neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis. Infections of the central nervous system, especially those characterized by a chronic progressive course, may produce multiple damage in infected and neighbouring cells. The activation of inflammatory processes and host immune responses cause chronic damage resulting in alterations of neuronal function and viability, but different pathogens can also directly trigger neurotoxic pathways. Indeed, viral and microbial agents have been reported to produce molecular hallmarks of neurodegeneration, such as the production and deposit of misfolded protein aggregates, oxidative stress, deficient autophagic processes, synaptopathies and neuronal death. These effects may act in synergy with other recognized risk factors, such as aging, concomitant metabolic diseases and the host's specific genetic signature. This review will focus on the contribution given to neurodegeneration by herpes simplex type-1, human immunodeficiency and influenza viruses, and by Chlamydia pneumoniae.

    Raqamlar

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