Clinical sciences

Question 1

What is alkaptonuria?

Answer 1

Alkaptonuria (ochronosis) is a rare autosomal recessive disorder of phenylalanine and tyrosine metabolism caused by a lack of the enzyme homogentisic dioxygenase (HGD) which results in a build-up of toxic homogentisic acid. The kidneys filter the homogentisic acid (hence black urine) but eventually it accumulates in cartilage and other tissues.

Question 2

What are the features of alkaptonuria?

Answer 2

Alkaptonuria is generally a benign and often asymptomatic condition. Possible features include:
pigmented sclera
urine turns black if left exposed to the air
intervertebral disc calcification may result in back pain
renal stones

Question 3

Alkaptonuria tx?

Answer 3

high-dose vitamin C
dietary restriction of phenylalanine and tyrosine

Question 4

Function of ADH ?

Answer 4

Antidiuretic hormone (ADH) is secreted from the posterior pituitary gland. It promotes water reabsorption in the collecting ducts of the kidneys by the insertion of aquaporin-2 channels.

Question 5

Source of ADH?

Answer 5

Synthesized in the supraoptic nuclei of the hypothalamus, released by the posterior pituitary

Question 6

Regulation of ADH?

Answer 6

Increases secretion
extracellular fluid osmolality increase
volume decrease
pressure decrease
angiotensin II

Decreases secretion
extracellular fluid osmolality decrease
volume increase
temperature decrease

hypothermia stimulates ADH to conserve water

Question 7

What is the role of leukotrines

Answer 7

Bronchoconstriction

Question 8

where do brain mets originate from?

Answer 8

Tumours that most commonly spread to the brain include:
lung (most common)
breast
bowel
skin (namely melanoma)
kidney

Question 9

Glioblastoma

Answer 9

most common primary tumour
poor prognosis
Solid tumour with centra necrosis
Histology - pleimorphic tumour cells border necrotic areas

Question 10

Meningioma?

Answer 10

Benign

Meningiomas are typically benign, extrinsic tumours of the central nervous system. They arise from the arachnoid cap cells of the meninges and are typically located next to the dura and cause symptoms by compression rather than invasion.

Histology: Spindle cells in concentric whorls and calcified psammoma bodies

Question 11

Vestibular schwanomma?

Answer 11

aka acoustic neuroma
arising from the eighth cranial nerve (vestibulocochlear nerve)
It presents with hearing loss, facial nerve palsy (due to compression of the nearby facial nerve) and tinnitus.

Associated with neurofibromatosis type 2

Question 12

Piloctyic astocytoma?

Answer 12

• The most common primary brain tumour in children
• Histology: Rosenthal fibres (corkscrew eosinophilic bundle)

Question 13

Medulloblastoma?

Answer 13

• A medulloblastoma is an aggressive paediatric brain tumour that arises within the infratentorial compartment. It spreads through the CSF system. Treatment is surgical resection and chemotherapy.
• Histology: Small, blue cells. Rosette pattern of cells with many mitotic figures

Question 14

Ependymoma?

Answer 14

• Commonly seen in the 4th ventricle
• May cause hydrocephalus
• Histology: perivascular pseudorosettes

Question 15

Oliogodendrome?

Answer 15

• Benign, slow-growing tumour common in the frontal lobes
• Histology: Calcifications with ‘fried-egg’ appearance

Question 16

Haemangioblastoma?

Answer 16

• Benign, slow-growing tumour common in the frontal lobes
• Histology: Calcifications with ‘fried-egg’ appearance

Question 17

Haemangioblastoma?

Answer 17

Vascular tumour of the cerebellum
* Associated with von Hippel-Lindau syndrome
* Histology: foam cells and high vascularity

Question 18

Pituitary adeoma?

Answer 18

• Pituitary adenomas are benign tumours of the pituitary gland. They are either secretory (producing a hormone in excess) or non-secretory. They may be divided into microadenomas (smaller than 1cm) or macroadenoma (larger than 1cm).
• Patients will present with the consequences of hormone excess (e.g. Cushing’s due to ACTH, or acromegaly due to GH) or depletion. Compression of the optic chiasm will cause a bitemporal hemianopia due to the crossing nasal fibers.
• Investigation requires a pituitary blood profile and MRI. Treatment can either be hormonal or surgical (e.g. transphenoidal resection).

Question 19

Craniopharyngioma?

Answer 19

• Most common paediatric supratentorial tumour
• A craniopharyngioma is a solid/cystic tumour of the sellar region that is derived from the remnants of Rathke’s pouch. It is common in children, but can present in adults also. It may present with hormonal disturbance, symptoms of hydrocephalus or bitemporal hemianopia.
• Histology: Derived from remnants of Rathke pouch
• Investigation requires pituitary blood profile and MRI. Treatment is typically surgical with or without postoperative radiotherapy.

Question 20

PTH

Answer 20

Increase calcium levels and decrease phosphate levels
Increases bone resorption
Immediate action on osteoblasts to increase ca2+ in extracellular fluid
Osteoblasts produce a protein signaling molecule that activate osteoclasts which cause bone resorption
Increases renal tubular reabsorption of calcium
Increases synthesis of 1,25(OH)2D (active form of vitamin D) in the kidney which increases bowel absorption of Ca2+
Decreases renal phosphate reabsorption

Question 21

1,25-dihydroxycholecalciferol (the active form of vitamin D)

Answer 21

Increases plasma calcium and plasma phosphate
Increases renal tubular reabsorption and gut absorption of calcium
Increases osteoclastic activity
Increases renal phosphate reabsorption in the proximal tubule

Question 22

Calcitonin

Answer 22

Secreted by C cells of thyroid
Inhibits osteoclast activity
Inhibits renal tubular absorption of calcium

Question 23

What is the left ventricular ejection feaction?

Answer 23

Left ventricular ejection fraction = (stroke volume / end diastolic LV volume ) * 100%

Question 24

Stroke volume?
Cardiac output?

Answer 24

Stroke volume = end diastolic LV volume - end systolic LV volume

Cardiac output = stroke volume x heart rate

Question 25

Pulse pressure?

Answer 25

Pulse pressure = Systolic Pressure - Diastolic Pressure Factors which increase pulse pressure a less compliant aorta (this tends to occur with advancing age) increased stroke volume

Question 26

Systemic vascular resistance

Answer 26

Systemic vascular resistance = mean arterial pressure / cardiac output

Question 27

What is CPP?

Answer 27

CPP= Mean arterial pressure - Intra cranial pressure

Question 28

Patau syndrome (trisomy 13)

Answer 28

Microcephalic, small eyes Cleft lip/palate Polydactyly Scalp lesions

Question 29

Edwards syndrome?

Answer 29

Trisomy 18 Micrognathia Low-set ears Rocker bottom feet Overlapping of fingers

Question 30

Fragile X

Answer 30

Learning difficulties Macrocephaly Long face Large ears Macro-orchidism

Question 31

Noonan syndrome?

Answer 31

Webbed neck Pectus excavatum Short stature Pulmonary stenosis

Question 32

Pierre-Robin syndrome

Answer 32

Micrognathia Posterior displacement of the tongue (may result in upper airway obstruction) Cleft palate

Question 33

Prader-Willi syndrome?

Answer 33

Hypotonia Hypogonadism Obesity

Question 34

Williams syndrome

Answer 34

Short stature Learning difficulties Friendly, extrovert personality Transient neonatal hypercalcaemia Supravalvular aortic stenosis

Question 35

Cri du chat syndrome (chromosome 5p deletion syndrome)

Answer 35

Characteristic cry (hence the name) due to larynx and neurological problems Feeding difficulties and poor weight gain Learning difficulties Microcephaly and micrognathism Hypertelorism

Question 36

Nominal data?

Answer 36

Observed values can be put into set categories which have no particular order or hierarchy. You can count but not order or measure nominal data (for example birthplace)

Question 37

Ordinal data

Answer 37

Observed values can be put into set categories which themselves can be ordered (for example NYHA classification of heart failure symptoms)

Question 38

Discrete data

Answer 38

Observed values are confined to a certain values, usually a finite number of whole numbers (for example the number of asthma exacerbations in a year)

Question 39

binominal data

Answer 39

Data may take one of two values (for example biological sex)

Question 40

Interval data

Answer 40

A measurement where the difference between two values is meaningful, such that equal differences between values correspond to real differences between the quantities that the scale measures (for example temperature)

Question 41

What is Digeorge syndrome?

Answer 41

DiGeorge syndrome is a primary immunodeficiency disorder caused by T-cell deficiency and dysfunction. It is an example of a microdeletion syndrome (deletion of a section of chromosome 22). It is also known as velocardiofacial syndrome and 22q11.2 deletion syndrome and is an autosomal dominant condition.

Question 42

What are the features of Digeorge syndrome?

Answer 42

It has a variable presentation however its features can be remembered with the mnemonic CATCH22: C - Cardiac abnormalities A - Abnormal facies T - Thymic aplasia C - Cleft palate H - Hypocalcaemia/ hypoparathyroidism 22 - Caused by chromosome 22 deletion