Colchicine is a

highly poisonous alkaloid, originally isolated from crocus. It is a very

effective mitotic poison that attacks the microtubules of the spindle

apparatus, thus disrupting the correct course of mitosis. Some drugs (such as

some chemotherapies) work by a similar mechanism by damaging the function or

structure of microtubules. Which particular process is so disrupted during

mitosis?

A newborn is

diagnosed with congenital deafness due to a defect in an intracellular protein.

This protein is a component of cell-cell junctions that form a pore connecting

the cytoplasm of adjacent cells. Which type of cell-cell junctions is defective in this patient?

A 63-year-old patient

suffers from type II diabetes. After a long time, she goes for an eye

examination and is diagnosed with one of the frequent complications of

diabetes, the so-called diabetic retinopathy. Diabetic retinopathy develops

over several years before clinical manifestations appear, and thickening of the

basal lamina of endothelial cells is one of the signs of this disease during

the clinically silent period, which is caused by the excessive synthesis of

basal lamina components due to hyperglycemia. What layers does the basal lamina

consist of?

A 17-year-old female patient has gradually developed symptoms such as fatigue, weakness, dyspnea on exertion and impaired

performance over several months. These symptoms gradually worsen over the last

year or so. She now comes for intense right hip pain. On further questioning,

she indicates frequent epistaxis (nosebleeds) and easy development of bruises.

During the physical examination, the physician notes striking pallor of the

skin and mucous membranes, tachycardia as well as hepatomegaly (enlargement of the

liver) and splenomegaly (enlargement of the spleen). Laboratory findings

confirm the presence of anemia and thrombocytopenia. A special finding is the

picture of the so-called Erlenmeyer flask deformity of the diaphyses of the

femurs. This sign is already suggestive to the physicians and the determination

of low activity of the enzyme β-glucocerebrosidase in isolated leukocytes

confirms the diagnosis of Gaucher disease. Gaucher disease is an inherited

lysosomal storage disease that is caused by a genetic defect in the lysosomal

enzyme glucocerebrosidase. This enzyme is responsible for the hydrolytic

cleavage of glucosylceramide to glucose and ceramide. What is the function of

lysosomes? What will their failure lead to in the cell?

A 54-year-old man underwent gastroscopy

(endoscopy of the upper digestive tract) for non-specific digestive disorders.

The oesophagus and stomach appear macroscopically fine, but changes are only

visible in the duodenum, where several samples are therefore taken for

histological examination. The final diagnosis is peptic duodenitis,

inflammation of the duodenum, which is a precursor to the development of the

ulcer. This inflammation is usually caused by the

A 43-year-old man comes to the physician because of weight

loss and swelling on the left side of his neck. Physical examination shows a

firm, enlarged cervical lymph node that is immobile. Immunohistochemical

testing performed on a biopsy specimen from the lymph node stains positive

for cytokeratin. Which of the following organ is the most likely site of

the primary cytokeratin-positive neoplasm in this patient?

Arrhythmia, i. e. irregularity of the heart rhythm, can be caused, for

example, by a high or low level of certain ions. Heart muscle cells

(cardiomyocytes) can exchange these ions with each other to maintain

homeostasis. Cardiomyocytes are connected by intercalated discs. What type of

intercellular junction is part of the intercalated discs and used for ion

exchange?

A new doctor at the Department of Paediatrics

and Inherited Metabolic Disorders gets acquainted with very rare syndromes. He

did not learn much about them in medical school, and because of their rarity,

they are mainly dealt with only by this department. These include rare

congenital disorders of glycosylation. These are diseases whose cause lies in

defects in the enzymes involved in the synthesis of the oligosaccharide chains

of glycoproteins. Glycoproteins are proteins that have oligosaccharide chains

covalently linked to a central protein chain. It is one of the

post-translational modifications of proteins. Most types of these diseases are

associated with neurological disorders, growth retardation, blood clotting

disorders, liver and gastrointestinal tract disease and typically manifest in

the neonatal or infant period. Where do these post-translational modifications

of proteins within the cell most commonly occur?

A 30-year-old patient underwent a biopsy of the

submandibular salivary gland in the ENT department due to significant swelling

of unclear origin. This eventually proves to be histologically normal. What is

this sample most likely to look like?