Miscellaneous Flashcards
HIV/AIDS
What group is HIV part of and what does this mean?
- Lentivirus group (retrovirus) meaning it encodes reverse transcriptase, allowing DNA copies to be produced from viral RNA – error prone, meaning a significant mutation rate contributing to treatment resistance.
HIV/AIDS
What is the initial response to HIV virus and how does it spread?
- Local inflammation with a mucosal macrophage/dendritic cell established before spreading to other cells.
- As these are antigen presenting cells, some migrate to local lymph nodes to present antigen to T cells where infection of T helper cells occurs.
HIV/AIDS
How does HIV bind to cells?
- Via its GP120 envelope glycoprotein to CD4 receptors on T helper cells, monocytes + macrophages.
HIV/AIDS
What happens once HIV has bound to CD4 receptors?
- CD4 cells migrate to lymphoid tissue where virus replicates with production of billions of new virions which are released + infect new CD4 cells.
HIV/AIDS
How does HIV replicate?
- Viral capsid enters, enzymes + nucleic acid uncoated + released.
- Reverse transcriptase makes single stranded RNA into double stranded DNA + viral DNA is integrated to host cell’s DNA via integrase.
HIV/AIDS
How does HIV lead to decreased immune function?
- Depletion/impaired function due to viraemia causes uncontrolled activation of CD4 T cells + so apoptosis of CD4 cells.
HIV/AIDS
Why is HIV not stopped?
- Able to avoid antibodies + CD8 cytotoxic T lymphocytes due to viral envelope glycoprotein being poorly immunogenic + mutations.
HIV/AIDS
What is the epidemiology of HIV?
- Mostly HIV-1, less HIV-2.
- Men > women as HIV spreads well by anal intercourse, very prevalent in male-male sexual activity.
- Majority of new infections worldwide are 15–24y/o.
HIV/AIDS
What are high risk groups for HIV?
- Homosexual men + heterosexual women.
- IV drug users.
- Commercial sex workers, truck drivers.
- Uncircumcised men.
HIV/AIDS
What are the routes of acquisition of HIV?
- Sexual intercourse (vaginal + anal), STIs enhance transmission.
- Mother-to-child in utero.
- Contaminated blood + organ donation (minimal in developed countries).
- Contaminated needles.
HIV/AIDS
What is the first stage in the clinical presentation of HIV?
Acute primary infection (seroconversion, 2–6 weeks)…
- Transient immunosuppression + fall in CD4 count followed by gradual rise.
- Acute rise in viral load then fall to set point.
- Transient, non-specific symptoms (fever, malaise, myalgia, rash).
HIV/AIDS
What is the second stage in the clinical presentation of HIV?
Asymptomatic phase (years)... - Clinical latency with progressive loss of CD4 T cells resulting in poor immunity but asymptomatic (spreads infection further).
HIV/AIDS
What is the third stage in the clinical presentation of HIV?
Early symptomatic HIV…
- Associated with rise in viral load + fall in CD4 count.
- Symptoms like fever, night sweats, diarrhoea.
- Opportunistic infections (herpes zoster, recurrent herpes simplex).
- Collection of symptoms is AIDS-related complex (ARC).
HIV/AIDS
What is the final stage in clinical presentation of HIV.
AIDS…
- Symptoms of immune deficiency with a CD4 <200uL.
HIV/AIDS
What is the natural time frame for HIV to AIDs development?
HIV>[8 years]>ARC>[2 years]>AIDS>[2 years]>death.
HIV/AIDS
What are AIDS defining conditions?
- Oesophageal candidiasis.
- Mycobacterium TB.
- Persistent herpes simplex.
- Kaposi’s carcinoma.
- Non-Hodgkin’s lymphoma.
- HIV dementia.
HIV/AIDS
What are the investigations for HIV?
Enzyme-linked immunosorbent assay (ELISA)…
- Can take up to 3 months for HIV antibody/antigen detection.
- Confirmatory assay diagnostic.
Rapid point of care testing…
- Immunoassay kit provides rapid result from finger-prick/mouth swab, needs serological confirmation.
Nucleic acid testing/viral PCR…
- Qualitative test for presence of viral RNA, used to aid diagnosis of HIV in babies.
HIV/AIDS
What methods are used to monitor HIV infection?
Viral load…
- Quantification of HIV RNA.
CD4 count…
- Monitors immune system function.
HIV/AIDS
What are the treatment for HIV?
High active antiretroviral therapy (HAART)…
- Before CD4<200uL is ideal.
Nucleoside reverse transcriptase inhibitors (NRTI)…
- Inhibit synthesis of DNA by reverse transcription + also act as DNA chain terminators.
Non-nucleoside reverse transcriptase inhibitors (NNRTI).
- Bind directly to + inhibits reverse transcriptase.
Protease inhibitors…
- Act competitively on HIV enzyme involved in production of functional viral proteins + enzymes.
Integrase inhibitors…
- Inhibits insertion of HIV DNA into human genome.
HIV/AIDS
What is the prevention of HIV?
- Education on transmission, contraception.
- Give IV drug users clean needles.
- Pre/post-exposure prophylaxis in high-risk individuals (antiretroviral therapy).
- Male circumcision.
BREAST CANCER
What is the pathophysiology of breast cancer?
- Can arise from epithelial lining of ducts (ductal) or epithelium of terminal ducts of lobules (lobular).
BREAST CANCER
What are the 4 types of breast cancer?
Invasive ductal carcinoma... - MOST common. Lobular carcinoma... - Accounts for 10–15% Medullary cancers... - Often younger patients. Colloid/mucoid cancers... - Often elderly patients.
BREAST CANCER
What is the epidemiology of breast cancer?
- 1/8 women (most common cancer in women, second most common cause of death in UK).
- Rare in men (1% of all breast cancers).
BREAST CANCER
What are the risk factors for breast cancer?
- BRCA1/BRCA2 mutations.
- Early menarche/late menopause.
- Continuous combined HRT.
- Increasing age, never having borne a child/first child after 30y/o.
- Not breastfeeding.