Biochemistry
1 questionsPhenylketonuria is due to deficiency of:
NEET-PG 2018 - Biochemistry NEET-PG Practice Questions and MCQs
Question 141: Phenylketonuria is due to deficiency of:
- A. Phenylalanine (amino acid)
- B. Tyrosine
- C. Phenylalanine hydroxylase (PAH) (Correct Answer)
- D. None of the options
Explanation: ***Phenylalanine hydroxylase (PAH)*** - **Phenylketonuria (PKU)** is an inherited metabolic disorder caused by a deficiency of the enzyme **phenylalanine hydroxylase (PAH)**. - This enzyme is crucial for converting the amino acid **phenylalanine** into **tyrosine**, and its deficiency leads to an accumulation of phenylalanine in the body. - PKU follows an **autosomal recessive** inheritance pattern. *Phenylalanine (amino acid)* - While **phenylalanine** accumulates to toxic levels in PKU, it is the substrate, not the deficient component. - The disease stems from the body's inability to metabolize this amino acid due to the enzyme deficiency. *Tyrosine* - **Tyrosine** is the product of the reaction catalyzed by PAH, and its production is limited in PKU. - However, the deficiency of tyrosine is a secondary effect, not the primary cause of PKU. *None of the options* - This option is incorrect because the deficiency of **phenylalanine hydroxylase (PAH)** is precisely the cause of Phenylketonuria.
Internal Medicine
2 questionsChoose the best method of diagnosis for the clinical sign represented in the image.
Which condition is associated with the ECG pattern known as pseudo P pulmonale?
NEET-PG 2018 - Internal Medicine NEET-PG Practice Questions and MCQs
Question 141: Choose the best method of diagnosis for the clinical sign represented in the image.
- A. Serum copper
- B. Serum ceruloplasmin (Correct Answer)
- C. Karyotyping
- D. PCR
Explanation: ***Serum ceruloplasmin*** - The image shows a **Kayser-Fleischer ring**, a greenish-brown discoloration in the periphery of the cornea, which is pathognomonic for **Wilson's disease**. - **Wilson's disease** is a genetic disorder of copper metabolism characterized by **low serum ceruloplasmin** levels (the primary copper-carrying protein in the blood) and increased copper deposition in various tissues. *Serum copper* - While Wilson's disease involves copper accumulation, **total serum copper** can be normal or even elevated due to widespread tissue damage releasing copper into the circulation, making it an unreliable diagnostic marker on its own. - A low serum copper level can be seen, but it is not as specific as low ceruloplasmin, as much of the copper in serum is bound to ceruloplasmin. *Karyotyping* - **Karyotyping** is used to analyze the number and structure of chromosomes and is primarily indicated for diagnosing chromosomal abnormalities, such as Down syndrome or Turner syndrome. - It is not relevant for diagnosing metabolic disorders like Wilson's disease, which is caused by a mutation in a single gene (ATP7B), not a chromosomal aberration. *PCR* - **PCR (Polymerase Chain Reaction)** is a technique used to amplify DNA sequences and can be used for genetic testing to identify specific mutations. - While genetic testing for the **ATP7B gene** mutation is a confirmatory test for Wilson's disease, it is not the primary or best method for initial diagnosis, especially when classic clinical signs and biochemical markers (like low ceruloplasmin) are present.
Question 142: Which condition is associated with the ECG pattern known as pseudo P pulmonale?
- A. Hyponatremia
- B. Hypocalcemia
- C. Hypokalemia
- D. Hypercalcemia (Correct Answer)
Explanation: ***Hypercalcemia*** - **Hypercalcemia** can cause a characteristic ECG pattern known as pseudo P pulmonale due to its effects on **myocardial repolarization**. - This condition leads to a **shortened QT interval** which causes the T wave to merge with the P wave, giving the appearance of a tall, peaked P wave. *Hypokalemia* - **Hypokalemia** typically presents with **flattened T waves**, prominent U waves, and ST-segment depression on an ECG [1]. - It can prolong repolarization, which is the opposite effect observed with pseudo P pulmonale [1]. *Hyponatremia* - **Hyponatremia** has a less defined direct effect on ECG patterns compared to other electrolyte imbalances. - Severe hyponatremia may lead to **QRS widening** or **bradycardia**, but not pseudo P pulmonale [1]. *Hypocalcemia* - **Hypocalcemia** characteristically causes **prolongation of the QT interval** on an ECG due to delayed ventricular repolarization [2]. - This is distinct from the shortened QT seen in hypercalcemia that contributes to pseudo P pulmonale.
Microbiology
2 questionsWhole blood is used as a sample for which of the following tests?
Sabin Feldman dye test is used for diagnosis of which of the following condition?
NEET-PG 2018 - Microbiology NEET-PG Practice Questions and MCQs
Question 141: Whole blood is used as a sample for which of the following tests?
- A. Genexpert
- B. Blood Culture for Bacteria
- C. Interferon Gamma Release Assay (IGRA) (Correct Answer)
- D. Serological Test for Viruses
Explanation: ***Interferon Gamma Release Assay (IGRA)*** - IGRAs, such as QuantiFERON-TB Gold, directly measure **interferon-gamma release** from T-lymphocytes stimulated by *Mycobacterium tuberculosis* antigens. - This test requires **fresh whole blood** as the living lymphocytes are essential for the immune response measured. *Blood Culture for Bacteria* - While blood is cultured, the primary goal is to **isolate and identify viable bacteria** from the bloodstream, not to detect an immune response within the whole blood itself. - Blood cultures typically involve placing blood into specific **culture media** to promote bacterial growth. *Genexpert* - The GeneXpert MTB/RIF assay is a **molecular test** used to detect *Mycobacterium tuberculosis* DNA and rifampicin resistance. - This assay is typically performed on **sputum samples** or other bodily fluids, not whole blood, to diagnose active tuberculosis. *Serological Test for Viruses* - Serological tests for viruses detect **antibodies or antigens** in the blood, which circulate in the **plasma or serum** component of blood. - These tests typically use **separated serum or plasma**, rather than whole blood, as the cellular components are not required for antibody or antigen detection.
Question 142: Sabin Feldman dye test is used for diagnosis of which of the following condition?
- A. Botulism
- B. Toxoplasmosis (Correct Answer)
- C. Sarcoidosis
- D. Yellow fever
Explanation: ***Toxoplasmosis*** The **Sabin-Feldman dye test** is a **serological assay** used to detect specific IgG antibodies against *Toxoplasma gondii*, the causative agent of toxoplasmosis. It measures the ability of antibodies in a patient's serum to prevent the cytoplasmic staining of live toxoplasma tachyzoites by methylene blue dye, indicating an **active immune response** to the parasite. This classic test has high sensitivity and specificity for detecting toxoplasma antibodies and is considered the gold standard serological test, though it has been largely replaced by ELISA and IFA in routine practice due to the requirement for live organisms. *Botulism* Botulism is diagnosed through **toxin detection** in serum, stool, or food samples using mouse bioassay, or by culturing *Clostridium botulinum* from clinical specimens. The Sabin-Feldman dye test is not relevant for the diagnosis of botulism, which is a **neuroparalytic disease** caused by botulinum neurotoxin blocking acetylcholine release at neuromuscular junctions. *Sarcoidosis* Sarcoidosis is a multisystem **granulomatous disease** diagnosed primarily by **tissue biopsy** showing non-caseating granulomas along with compatible clinical and radiological findings. Supportive tests include elevated serum ACE levels and Kveim test (historical). There is no serological test like the Sabin-Feldman dye test associated with the diagnosis of sarcoidosis, as it is not an infectious disease requiring antibody detection. *Yellow fever* Yellow fever is a **viral hemorrhagic disease** caused by a flavivirus, diagnosed by detecting viral RNA through RT-PCR or specific IgM antibodies in the acute phase of infection using ELISA or immunofluorescence. The Sabin-Feldman dye test is not used for viral infections like yellow fever, as it specifically targets **toxoplasma antibodies** and has no role in arboviral disease diagnosis.
Pathology
4 questionsStruvite stones are primarily composed of which metal?
Positive periodic acid-Schiff (PAS) macrophages are seen in which of the following conditions?
Which of the following is the carrying agent for Lyme disease?
Identify the condition represented in the image of a testicular tumor.
NEET-PG 2018 - Pathology NEET-PG Practice Questions and MCQs
Question 141: Struvite stones are primarily composed of which metal?
- A. Magnesium (Correct Answer)
- B. Calcium
- C. Sodium
- D. Potassium
Explanation: ***Magnesium*** - **Struvite stones** are primarily composed of **magnesium ammonium phosphate**, formed in the presence of urease-producing bacteria. - The presence of magnesium is a defining component of these **infection-related stones**. *Calcium* - **Calcium** is the primary component of the most common type of kidney stones, **calcium oxalate** and **calcium phosphate stones**. - These are typically unrelated to bacterial infections, unlike struvite stones. *Sodium* - **Sodium** is not a primary component of any common type of kidney stone. - While high sodium intake can increase the risk of stone formation, it does not directly form the stone matrix. *Potassium* - **Potassium** is not a characteristic component of kidney stones. - It plays a role in urinary pH regulation but is not directly incorporated into stone formation.
Question 142: Positive periodic acid-Schiff (PAS) macrophages are seen in which of the following conditions?
- A. Whipple's disease (Correct Answer)
- B. Crohn's disease
- C. HIV/AIDS
- D. Celiac disease
Explanation: ***Whipple's disease*** - **Whipple's disease** is caused by the bacterium *Tropheryma whipplei*, which is ingested by macrophages and accumulates in their lysosomes [1]. - The bacterial cell wall contains **glycoproteins** and **proteoglycans** that stain magenta (red-purple) with the **periodic acid-Schiff (PAS)** stain. - PAS-positive, diastase-resistant macrophages in the lamina propria of the small intestine are **pathognomonic** for Whipple's disease [1]. *Crohn's disease* - Crohn's disease is an **inflammatory bowel disease** characterized by transmural inflammation and non-caseating granulomas. - While it involves macrophages in the inflammatory process, they do not typically show **PAS-positive inclusions**. *HIV/AIDS* - HIV/AIDS is a **viral infection** that primarily targets CD4+ T lymphocytes and macrophages. - Although macrophages are involved in HIV infection and can be found in intestinal tissue, they do not exhibit **PAS-positive inclusions** characteristic of Whipple's disease. *Celiac disease* - Celiac disease is an **autoimmune enteropathy** triggered by gluten, causing villous atrophy and malabsorption. - The histology shows increased intraepithelial lymphocytes and crypt hyperplasia, but **macrophages are not PAS-positive**. - Both Whipple's and celiac disease can present with malabsorption, making clinical differentiation important [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 798-799.
Question 143: Which of the following is the carrying agent for Lyme disease?
- A. Anopheles
- B. Ixodes scapularis ticks (Correct Answer)
- C. Louse
- D. Rat flea
Explanation: ***Ixodes scapularis ticks*** - *Ixodes scapularis* ticks (deer ticks) are the primary **vectors for Lyme disease** (caused by *Borrelia burgdorferi*) in North America [1]. - In Europe, *Ixodes ricinus* is the main vector for Lyme disease. - Lyme disease presents with characteristic **erythema migrans** rash, followed by potential neurological, cardiac, and arthritic complications [1]. - Lyme arthritis commonly affects large joints, particularly the **knee**, causing inflammatory arthritis [1]. *Anopheles* - **Anopheles mosquitoes** are the primary vectors for **malaria**, not Lyme disease [2]. - Malaria is caused by *Plasmodium* parasites and presents with fever, chills, and hemolytic anemia [2]. *Louse* - **Lice** are vectors for diseases such as **epidemic typhus** (caused by *Rickettsia prowazekii*) and **relapsing fever** (caused by *Borrelia recurrentis*) [3]. - They are not associated with the transmission of Lyme disease. *Rat flea* - **Rat fleas** (e.g., *Xenopsylla cheopis*) are the primary vectors for **bubonic plague** (caused by *Yersinia pestis*) and **murine typhus**. - These insects do not transmit Lyme disease. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 389-390. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, p. 400. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 392-393.
Question 144: Identify the condition represented in the image of a testicular tumor.
- A. Non-seminomatous germ cell tumor
- B. Teratoma (testicular tumor)
- C. Seminoma (Correct Answer)
- D. Leydig cell tumor
Explanation: ***Seminoma*** - Seminoma is a type of **germ cell tumor** that typically presents with a **painless testicular mass**, making it one of the common types of testicular cancer [1]. - This condition is characterized by the presence of **large, uniform cells** and is highly sensitive to **radiation therapy**, which aids in management [1]. *Non-seminoma* - Non-seminomas encompass a group of tumors including **embryonal carcinoma**, **choriocarcinoma**, and **yolk sac tumor**, which often present with more variable histological features [1]. - Generally considered more aggressive than seminomas, they may yield **higher levels of tumor markers** such as **AFP** or **hCG** [1]. *Teratoma* - Teratomas typically contain **multiple germ layers (ectoderm, mesoderm, and endoderm)**, often presenting with more complex histopathology compared to seminomas [1]. - They can occur in both children and adults, but in adults, they are often a component of a **non-seminomatous germ cell tumor** instead of a pure form [1,2]. *Germ cell differentiate tumor* - This term broadly refers to any tumor originating from **germ cells**, including both seminomas and non-seminomas, lacking specificity [1]. - It does not reflect the defined characteristics of seminoma and can encompass a range of histological types with diverse behaviors [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lower Urinary Tract and Male Genital System, pp. 979-982. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 512-513.
Pharmacology
1 questionsWhich of the following statements about vitamin K is correct?
NEET-PG 2018 - Pharmacology NEET-PG Practice Questions and MCQs
Question 141: Which of the following statements about vitamin K is correct?
- A. All of the options are true
- B. Vitamin K acts as an anticoagulant
- C. Prolonged use of antimicrobials can lead to vitamin K deficiency (Correct Answer)
- D. The recommended dietary allowance for vitamin K is 200-300 micrograms per day
Explanation: ### Prolonged use of antimicrobials can lead to vitamin K deficiency - Long-term use of **broad-spectrum antimicrobials** can reduce the populations of gut bacteria that synthesize **vitamin K**, leading to a deficiency [1]. - This is particularly relevant because a significant portion of the body's vitamin K supply, especially **K2 (menaquinone)**, comes from microbial production in the intestines [1]. ### Vitamin K acts as an anticoagulant - Vitamin K is essential for the synthesis of **coagulation factors II, VII, IX, and X**, as well as protein C and S [3]; therefore, it is a **procoagulant**, not an anticoagulant [2]. - **Anticoagulants** like **warfarin** work by *inhibiting* vitamin K's action, thereby preventing the activation of these clotting factors [2], [3]. ### All of the options are true - This statement is incorrect because, as explained above, vitamin K is a **procoagulant**, not an anticoagulant. - The other statements also contain inaccuracies regarding vitamin K's function and recommended daily allowance. ### The recommended dietary allowance for vitamin K is 200-300 micrograms per day - The recommended daily allowance (RDA) for vitamin K in adults is significantly lower, typically **90 micrograms per day for women** and **120 micrograms per day for men**, not 200-300 micrograms [1]. - Excessive intake of vitamin K is generally not a concern as it has low toxicity due to its limited storage in the body.