NEET-PG 2012 Practice Questions

Q: In the context of epidemiology, what is the denominator used for calculating incidence?

Population at risk. ***Population at risk*** - Incidence measures the **rate of new cases** of a disease in a population over a specified period. - The denominator for calculating incidence must exclude individuals who are **already diseased** or are **immune** and thus not susceptible to developing the condition. - This is the **most accurate and theoretically correct** denominator as it represents only those who can actually develop the disease. *Mid year population* - While often used as a **practical approximation** in epidemiological calculations when the exact population at risk is difficult to determine. - However, it includes individuals who may not be at risk (e.g., already have the disease or are immune), making it **less precise** than using the actual susceptible population. - For the **theoretical definition** of incidence rate, population at risk is the correct denominator. *Total number of cases* - This value represents the **numerator** for incidence calculations, as it counts the number of new events or diseases occurring. - It cannot serve as the denominator, as the denominator must reflect the pool of individuals from which these **new cases arose**. *Total number of deaths* - This is a measure of **mortality**, not incidence, and is used to calculate death rates. - The denominator for mortality rates is typically the **population at risk of death**, not specifically the population at risk of developing a disease.

Q: Measles vaccination is given at -

9 months. ***9 months*** - The first dose of the **measles vaccine (MMR)** is typically administered at **9 months** of age in many national immunization programs. - This timing is chosen because maternal antibodies, which can interfere with vaccine effectiveness, generally wane by this age. *At birth* - Vaccines given at birth, such as **Hepatitis B** and **BCG**, target diseases with early exposure risks or have efficacy despite maternal antibodies. - Giving measles vaccine at birth would be ineffective due to the presence of **maternal antibodies** that neutralize the vaccine virus. *4 weeks* - This age is generally too early for measles vaccination as significant levels of **maternal antibodies** are often still present, which would reduce the vaccine's efficacy. - Other vaccines, like the rotavirus vaccine, might be given around this age, but not measles. *8 weeks* - While maternal antibodies might be decreasing, 8 weeks of age is still generally considered too early for optimal measles vaccine response. - Many primary vaccine series (e.g., DTaP, IPV, Hib) begin at 6-8 weeks, but measles is usually delayed further for better efficacy and seroconversion rates.

Q: What is the most common cause of ophthalmoplegia in adults?

Cranial nerve palsy. ***Cranial nerve palsy*** - **Cranial nerve palsies**, particularly those affecting cranial nerves III, IV, or VI, are the most frequent causes of isolated ophthalmoplegia in adults [1]. - They can result from various etiologies like **ischemia**, **compression**, or **inflammation**, directly impairing the nerves responsible for eye movement [1]. *Myasthenia gravis* - While it frequently causes **ocular symptoms** (ptosis and diplopia), it typically presents with **fluctuating weakness** that worsens with sustained effort [1]. - It's a neuromuscular junction disorder, not a primary cranial nerve issue, and often affects other muscle groups beyond the eyes. *Diabetes mellitus* - **Diabetic ophthalmoplegia** is a specific type of cranial nerve palsy (often CN III or VI) caused by microvascular ischemia. - While common in diabetics, it is a *cause* of cranial nerve palsy, not the overarching most common cause of ophthalmoplegia itself. *Trauma* - **Trauma** can certainly cause ophthalmoplegia, often due to direct damage to **extraocular muscles**, **orbital fractures**, or **cranial nerve injury**. - However, in the general adult population, non-traumatic cranial nerve palsies are more frequently encountered as the cause of ophthalmoplegia.

Q: Which antibody is elevated in parasitic infections?

IgE. **Correct: IgE** - **IgE** is centrally involved in the immune response to **parasitic infections**, particularly helminths. - This antibody promotes the release of inflammatory mediators from **mast cells** and **basophils**, leading to the expulsion of parasites. - Elevated IgE is a **characteristic finding** in helminthic infections and is used diagnostically. *Incorrect: IgA* - **IgA** is primarily found in **mucosal secretions** and plays a key role in protecting against pathogens at mucosal surfaces. - While it has a role in general immunity, it is **not the primary antibody** involved in the systemic response to parasitic infections. *Incorrect: IgG* - **IgG** is the most abundant antibody in serum and provides **long-term immunity** against many pathogens. - While IgG levels may rise in response to chronic parasitic infections, it is **not the characteristic or primary antibody** elevated in active or initial parasitic responses. *Incorrect: IgM* - **IgM** is the first antibody produced during a **primary immune response** and is important for activating the complement system. - While it indicates an early infection, it is **less specific** for parasitic infections compared to IgE.

Q: Which atypical mycobacteria are known for pigment production?

M. gordonae, M. szulgai. **Correct: M. gordonae, M. szulgai** - **M. gordonae** is a classic **scotochromogen**, producing yellow-orange pigment in both light and dark conditions - **M. szulgai** is unique as it shows **dual chromogenicity**: photochromogen at 25°C and scotochromogen at 37°C - These are the classic examples of **pigment-producing atypical mycobacteria** used for classification purposes - Pigment production (Runyon classification) is a key characteristic differentiating atypical mycobacteria from *M. tuberculosis* *Incorrect: M. fortuitum, M. chelonae* - These are **rapid growers** (Runyon Group IV) and are typically **non-chromogens** - Not primarily known or highlighted for pigment production as a defining feature - Clinically important for causing **skin and soft tissue infections**, especially in post-traumatic or post-surgical settings *Incorrect: M. xenopi, Mycobacterium avium complex (MAC)* - **M. xenopi** is a **non-chromogen** (no pigment production) and is thermophilic - **MAC** (*M. avium* and *M. intracellulare*) are also **non-chromogens** - MAC is an important cause of disseminated disease in immunocompromised patients (especially AIDS) and pulmonary disease in patients with pre-existing lung disease *Incorrect: M. ulcerans (non-pigment producing)* - Correctly identified as a **non-chromogen** (no pigment production) - Causes **Buruli ulcer**, a severe necrotizing skin disease - Distinguished by production of **mycolactone toxin**, not pigment characteristics

Q: Among the following organisms, which is the most common cause of postoperative endophthalmitis following corneal transplantation?

Staph epidermidis. ***Staph epidermidis*** - **Coagulase-negative Staphylococcus** (CoNS), including *S. epidermidis*, is the most frequent cause of **postoperative endophthalmitis** after both cataract surgery and corneal transplantation due to its presence on the normal ocular flora. - These organisms can form **biofilms on intraocular lenses** or transplanted corneal tissue, making eradication difficult. *Streptococcus* - While *Streptococcus* species can cause endophthalmitis, they are associated with a **more virulent and rapid onset** of severe inflammation and are not the most common causative agents of postoperative endophthalmitis compared to *S. epidermidis*. - They tend to cause more aggressive infections with often **poorer visual outcomes**. *Propionibacterium acnes* - *Propionibacterium acnes* can cause a **late-onset, indolent form of endophthalmitis**, typically months or even years after surgery. - While it is a recognized cause, it is far **less common** than *Staphylococcus epidermidis* in immediate or early postoperative cases. *Pseudomonas* - **Pseudomonas aeruginosa** is an aggressive and rapid-onset pathogen often associated with **severe keratitis** or **post-traumatic endophthalmitis**. - Although it can cause postoperative endophthalmitis, it is **much less common** than coagulase-negative staphylococci due to its infrequency on normal conjunctival flora.

Q: Which gene mutation is commonly associated with malignant melanoma?

CDKN2A. ***CDK2A*** - CDK2A mutations are implicated in malignant melanoma as they disrupt the **cell cycle regulation**, contributing to uncontrolled cell growth [1]. - Loss of CDK2A function leads to reduced **p16INK4A**, a crucial inhibitor of cyclin-dependent kinases involved in **G1/S phase transition** [1,3]. - Germline mutations of p16 (CDKN2A) are present in 25% of melanoma-prone kindreds [2], and germline mutations in CDKN2A are associated with familial forms of melanoma [3]. *RET* - RET mutations are primarily associated with **medullary thyroid carcinoma** and **multiple endocrine neoplasia type 2**, not melanoma. - It is involved in the signaling pathways but does not have a direct link to melanoma pathogenesis. *None* - Suggesting "none" misrepresents the reality that specific mutations do occur in malignant melanoma, including **CDK2A** and **BRAF**. - This option fails to recognize the importance of genetic alterations in cancer development and progression. *N-myc* - N-myc mutations are primarily associated with **neuroblastoma** and not typically linked to malignant melanoma. - In melanoma, mutations of this gene do not play a significant role in its pathophysiology compared to another tumor suppressor gene like **CDK2A**. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Skin, pp. 1150-1151. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 297-298. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 305-306.

Q: All are true regarding Sunitinib except which of the following?

It is excreted primarily in urine. ***It is excreted primarily in urine*** - **Sunitinib** is predominantly metabolized in the **liver** by CYP3A4 and primarily excreted in the **feces**, not urine. - Its major active metabolite, N-desethyl sunitinib, is also primarily eliminated via the fecal route. *It inhibits tyrosine kinase receptors* - **Sunitinib** is a **multitargeted receptor tyrosine kinase (RTK) inhibitor**. - It blocks several RTKs involved in tumor growth, angiogenesis, and metastatic progression, such as **VEGFR, PDGFR, KIT, and FLT3**. *It is used for the treatment of GIST* - **Sunitinib** is approved for the treatment of **imatinib-refractory** or **imatinib-intolerant gastrointestinal stromal tumors (GIST)**. - Its mechanism in GIST involves inhibiting KIT and PDGFR, which are often mutated and constitutively active in this cancer. *It is used for renal cell carcinoma* - **Sunitinib** is a standard first-line treatment for **advanced renal cell carcinoma (RCC)**. - Its efficacy in RCC is primarily due to its inhibition of VEGFR, which targets the high vascularity characteristic of kidney tumors.

Q: Side effects of thiazide diuretics include all of the following except?

Hypocalcemia. ***Hypocalcemia*** - Thiazide diuretics are known to cause **hypercalcemia** (increased calcium reabsorption), NOT hypocalcemia, due to their action on the distal convoluted tubule. - This property makes them useful in treating conditions like **idiopathic hypercalciuria** and **calcium-containing kidney stones**. - The mechanism involves enhanced passive calcium reabsorption in the proximal tubule and active reabsorption in the distal tubule. *Hyponatremia* - Thiazide diuretics impair the kidney's ability to dilute urine and reabsorb sodium in the distal tubule, leading to **increased sodium excretion** and potential hyponatremia. - This effect is more pronounced in **elderly patients** and those with increased free water intake. - Hyponatremia is one of the most common electrolyte disturbances with thiazides. *Hypokalemia* - Thiazides increase the delivery of sodium and water to the collecting duct, leading to increased activity of the **renin-angiotensin-aldosterone system** and enhanced potassium secretion. - This results in **potassium wasting** and hypokalemia, which may require potassium supplementation or combination with potassium-sparing diuretics. *Erectile dysfunction* - Thiazide diuretics can cause **erectile dysfunction** through mechanisms including effects on vascular smooth muscle, reduced blood flow, and possible hormonal effects. - This is a common side effect reported in male patients using these medications for hypertension and may affect compliance.

Question 1

In the context of epidemiology, what is the denominator used for calculating incidence?

Accepted Answer

Population at risk

Answer

Mid year population

Answer

Total number of cases

Answer

Total number of deaths

Question 2

Measles vaccination is given at -

Accepted Answer

9 months

Answer

At birth

Answer

4 weeks

Answer

8 weeks

Question 3

An 86-year-old lady presented with severe constipation. She was a known hypertensive on medications for 10 years. In clinic, her BP was 157/98 mm Hg with a heart rate of 58/min. On taking her BP in the supine position, it was found to be 90/60 mm Hg. She had a recent history of depression. She is taking atenolol, thiazide, imipramine, haloperidol, and docusate. What is the next best step in the management?

Accepted Answer

Change imipramine and haloperidol to fluoxetine and risperidone and add bisacodyl for constipation

Answer

Change atenolol and thiazide to calcium channel blocker and ACE inhibitor and add bisacodyl for constipation

Answer

Only add bisacodyl for constipation and continue rest of the medications

Answer

Discontinue all her medications and start her on steroids

Question 4

What is the most common cause of ophthalmoplegia in adults?

Accepted Answer

Cranial nerve palsy

Answer

Myasthenia gravis

Answer

Diabetes mellitus

Answer

Trauma

Question 5

Which antibody is elevated in parasitic infections?

Accepted Answer

IgE

Answer

IgA

Answer

IgG

Answer

IgM

Question 6

Which atypical mycobacteria are known for pigment production?

Accepted Answer

M. gordonae, M. szulgai

Answer

M. fortuitum, M. chelonae

Answer

M. xenopi, Mycobacterium avium complex (MAC)

Answer

M. ulcerans (non-pigment producing)

Question 7

Among the following organisms, which is the most common cause of postoperative endophthalmitis following corneal transplantation?

Accepted Answer

Staph epidermidis

Answer

Streptococcus

Answer

Pseudomonas

Answer

Propionibacterium acnes

Question 8

Which gene mutation is commonly associated with malignant melanoma?

Accepted Answer

CDKN2A

Answer

MYCN

Answer

RET

Answer

BRAF

Question 9

All are true regarding Sunitinib except which of the following?

Accepted Answer

It is excreted primarily in urine

Answer

It inhibits tyrosine kinase receptors

Answer

It is used for the treatment of GIST

Answer

It is used for renal cell carcinoma

Question 10

Side effects of thiazide diuretics include all of the following except?

Accepted Answer

Hypocalcemia

Answer

Hypokalemia

Answer

Erectile dysfunction

Answer

Hyponatremia

NEET-PG 2012

Community Medicine

General Medicine

Internal Medicine

Microbiology

Ophthalmology

Pathology

Pharmacology