Medical Science Test 1 Nddc Scholarship

Carcinoid syndrome occurs when a carcinoid tumour (usually in the gastrointestinal tract) secretes excessive amounts of serotonin and other vasoactive substances into the systemic circulation. This results in a classic triad of cutaneous flushing, diarrhoea, and right-sided heart failure. The serotonin causes fibrosis of the tricuspid and pulmonary valves. Interestingly, the left side of the heart is usually spared because the lungs contain enzymes that break down the serotonin before it reaches the left atrium.

Wiskott-Aldrich Syndrome (WAS) is an X-linked recessive disorder characterised by the triad of eczema, thrombocytopenia (low platelet count with small platelets), and recurrent infections. Laboratory findings typically show low to normal IgG and IgM, but significantly elevated levels of IgA and IgE. This condition is caused by a mutation in the WAS protein, which is essential for the actin cytoskeleton in white blood cells and platelets.

Reiter's syndrome, now more commonly referred to as Reactive Arthritis, is often described by the classic mnemonic: 'Can't see (conjunctivitis), can't pee (urethritis), can't climb a tree (arthritis)'. It is an autoimmune condition that develops following an infection in another part of the body, usually the intestines or urinary tract. It is significantly more prevalent in young men and is strongly associated with the HLA-B27 genetic marker.

Kartagener's syndrome is a form of Primary Ciliary Dyskinesia. It is a genetic condition where the dynein arms of cilia are missing or defective. Because cilia are responsible for moving mucus out of the sinuses and lungs, patients suffer from chronic sinusitis and bronchiectasis. Furthermore, since the tails of sperm are essentially modified cilia (flagella), males are often infertile due to immotile sperm. A unique feature is 'situs inversus', where the major visceral organs are reversed or mirrored from their normal positions.

Sjögren's syndrome is a chronic autoimmune disorder where the body's immune system attacks the glands that produce moisture, particularly the lacrimal (tear) and salivary glands. This leads to the primary symptoms of dry eyes (xerophthalmia) and dry mouth (xerostomia). It is frequently associated with other rheumatic disorders like rheumatoid arthritis and is diagnosed in women about nine times more often than in men.

Ehlers-Danlos Syndrome (EDS) is a group of inherited connective tissue disorders caused by defects in the structure or synthesis of collagen. Because collagen is the 'glue' that holds the body together, its deficiency results in fragile, stretchy skin and joints that can move far beyond the normal range of motion. This can lead to frequent joint dislocations, chronic pain, and in some subtypes, dangerous complications involving blood vessel fragility.

Goodpasture's syndrome is an autoimmune disease in which antibodies (anti-GBM antibodies) attack the basement membrane in both the lungs and the kidneys. This results in bleeding from the lungs (haemoptysis) and kidney inflammation (glomerulonephritis) leading to blood in the urine (haematuria). It is a medical emergency that requires rapid treatment with plasmapheresis to remove the circulating antibodies.

Brown-Séquard syndrome is caused by a hemisection (damage to one half) of the spinal cord. Because the motor tracts (corticospinal) cross higher up in the brainstem, damage to the cord results in paralysis on the same side as the injury (ipsilateral). However, the spinothalamic tracts, which carry pain and temperature signals, cross to the opposite side shortly after entering the cord. Therefore, a lesion on the right side of the cord results in a loss of pain and temperature sensation on the left side (contralateral).

Thoracic Outlet Syndrome (TOS) occurs when the nerves or blood vessels in the space between your collarbone and your first rib (thoracic outlet) are compressed. When the lower roots of the brachial plexus (C8 and T1) are involved, it primarily affects the ulnar nerve distribution, leading to pain in the arm and significant weakness or atrophy (wasting) of the intrinsic hand muscles. This can be caused by physical trauma, repetitive injuries, or anatomical variations like an extra 'cervical rib'.

Krabbe's disease, also known as globoid cell leukodystrophy, is a severe neurological condition caused by a deficiency of the enzyme galactocerebrosidase. This leads to the destruction of the protective myelin sheath around nerve cells. It is an autosomal recessive condition. Clinical features include spasticity (stiffness and involuntary muscle contractions), optic nerve atrophy leading to vision loss, and developmental delay. While systemic illness can occur, nausea is a non-specific symptom and is not a defining characteristic used to identify or diagnose this primary neurodegenerative disorder.