MDS PREP
Examples of oncofoetal antigen is/are:
1. á -fetoprotein
2. Carcinoembryonic antigen
3. A and B
4. None of the above
Pathology Answer: 3
Oncofoetal antigens are substances that are normally present in the
developing fetus but are found in abnormally high quantities in the tissues of
certain cancer cells. These antigens are proteins that can be used as markers
for the detection of certain types of cancers. The presence of these antigens in
cancer cells suggests that the tumor cells have partially reverted to a more
primitive, embryonic stage of development.
Explanation for each option:
1. á-Fetoprotein (AFP): This is an oncofoetal antigen. It is a glycoprotein that
is produced by the liver cells of the developing fetus. In adults, the
production of AFP is usually very low. However, in cases of certain cancers such
as hepatocellular carcinoma (primary liver cancer) and some types of testicular
cancer, the tumor cells start producing AFP in large amounts. Therefore, high
levels of AFP in the blood can be indicative of these cancers.
2. Carcinoembryonic antigen (CEA): CEA is another example of an oncofoetal
antigen. It is a glycoprotein that is present in the gastrointestinal tract,
pancreas, and sometimes in the respiratory and reproductive systems of a
developing fetus. In adults, CEA levels are typically very low. However, in
certain types of cancers, such as colorectal cancer, gastric cancer, and some
forms of lung, pancreatic, and breast cancer, the tumor cells may start
producing large amounts of CEA, which can be detected in the blood and used as a
tumor marker for these malignancies.
3. A and B: Both α-fetoprotein and carcinoembryonic antigen are examples of
oncofoetal antigens, so this option is correct.
Which of the following is responsible for autoimmunity in Epstein-Barr virus infection?
1) Molecular mimicry
2) Polyclonal B-cell activation
3) Upregulation of co-stimulatory molecules
4) Antigenic cross-reactivity
General Pathology
Answer: 2
Polyclonal B-cell activation is responsible for autoimmunity in Epstein-Barr virus infection, leading to various autoimmune manifestations.
Which of the following is the most common cause of hypothyroidism in adults leading to myxedema?
1) Cretinism
2) Grave's disease
3) Hyperthyroidism
4) Hashimoto's thyroiditis
Hashimoto's thyroiditis is the most common cause of hypothyroidism in adults leading to myxedema.
Tetracycline stains appear as
1. Yellow and brown stains in enamel and dentin
2. Yellow and brown stains only in enamel
3. Yellow and brown stains only in dentin
4. Only yellow stain in enamel
Oral Pathology
Answer: 1
Tetracycline stains appear as yellow and brown stains in both enamel and dentin.
Which of the following describes the condition characterized by acute arthritis, conjunctivitis, urethritis, and associated mucocutaneous lesions?
1) Gout
2) Lyme disease
3) Reiter's syndrome
4) Rheumatoid arthritis
Reiter's syndrome is characterized by the classic triad of acute arthritis, conjunctivitis, and urethritis, often following a genitourinary or gastrointestinal infection.
In the lipooxygenase pathway of the arachidonic acid metabolism, which of the following products helps to promote platelet aggregation and vasoconstriction?
1) C5a
2) Thromboxane A2
3) Leukotriene B4
4) C1 activators
General Pathology
Answer: 2
Thromboxane A2, produced in the lipooxygenase pathway, promotes platelet aggregation and vasoconstriction, playing a key role in hemostasis.
The extracellular polysaccharide synthesized by cariogenic streptococci in the presence of excess sucros is best described as
1) Mucopolysaccharide
2) Dextran-like glucan
3) Glycogen-like glucan
4) Amylopectin
Oral Pathology
Answer: 2
Cariogenic streptococci, particularly Streptococcus mutans, synthesize extracellular polysaccharides when exposed to high levels of sucrose. These polysaccharides are primarily dextran-like glucans, which are formed from the polymerization of glucose units. Dextran contributes to the formation of dental plaque and biofilm, facilitating the adherence of bacteria to tooth surfaces and promoting caries development.
Giant cells are a characteristic histopathologic finding in
1. Aphthous ulcers
2. Aneurysmal bone cyst
3. Brown tumour of hyper parathyroidism
4. Dentigerous cyst
Oral Pathology
Answer: 2
Giant cells are a characteristic histopathologic finding in an aneurysmal bone cyst.