Human Health and Disease

HIV is a retrovirus that binds to the CD4 receptor protein present on the surface of helper T-lymphocytes (and macrophages).
Helper T-lymphocytes are therefore also called T4 or CD4 cells.
After entering, the virus replicates in these cells and produces progeny viruses, which attack other helper T cells, leading to a progressive decrease in their number.
Helper T cells are needed to activate B cells and cytotoxic T cells, so the whole immune system becomes weak and the person suffers from opportunistic infections.
So HIV principally infects the T4 lymphocytes.

Sedatives and tranquillisers depress the activity of the brain and produce feelings of calmness, relaxation and drowsiness.
Valium (diazepam) is a benzodiazepine tranquilliser, used to treat anxiety and sleeplessness. So it produces these effects.
Morphine is an opiate narcotic, used as a powerful painkiller.
Hashish is a cannabinoid that alters thoughts, perceptions and feelings (hallucinogenic effect).
Amphetamines are stimulants that increase alertness and activity.
So the drug that depresses brain activity and produces calmness, relaxation and drowsiness is Valium.

The thymus is a primary lymphoid organ located near the heart, beneath the breastbone. It is large in children and degenerates with age.
Immature lymphocytes formed in the bone marrow migrate to the thymus, where they mature into T-lymphocytes under the influence of thymosins.
T-lymphocytes are responsible for cell mediated immunity (CMI), such as the rejection of grafts and the killing of virus-infected cells.
So damage to the thymus in a child leads to a deficiency of T-cells and hence to the loss of cell mediated immunity.
Antibody mediated immunity depends mainly on B-lymphocytes, which mature in the bone marrow; haemoglobin and stem cells are produced in the bone marrow.
So damage to the thymus may lead to the loss of cell mediated immunity.

Meat, lentils (pulses), milk and eggs are rich sources of protein.
Kwashiorkor is caused by the deficiency of protein in the diet, even when the calorie intake may be adequate; it occurs mostly in children weaned early and fed on carbohydrate-rich food.
It is marked by wasting of muscles, thinning of limbs, failure of growth and brain development, and oedema (swelling) of parts of the body.
So such a patient is specially advised to take protein-rich foods.
Anaemia needs iron, folic acid and vitamin $B_{12}$; scurvy needs vitamin C (citrus fruits); rickets needs vitamin D and calcium.
So the diet is advised when the patient suffers from kwashiorkor.