Dermatology
1 questionsRaindrop pigmentation is caused by?
NEET-PG 2012 - Dermatology NEET-PG Practice Questions and MCQs
Question 771: Raindrop pigmentation is caused by?
- A. Dapsone
- B. Minocycline
- C. Clofazimine
- D. Arsenic (Correct Answer)
Explanation: ***Arsenic*** - Chronic **arsenic** exposure can lead to characteristic skin manifestations, including **raindrop pigmentation**, which appears as small, scattered hypopigmented macules surrounded by hyperpigmented skin, particularly on the trunk and extremities. - This pigmentation is a result of altered **melanin distribution** and **keratinocyte damage** due to arsenic toxicity. *Clofazimine* - **Clofazimine** is an anti-leprosy drug that can cause **reddish-brown to bluish-black skin discoloration**, which is a diffuse pigmentation, not "raindrop" in nature. - The pigmentation associated with clofazimine is due to drug deposition in tissues and is usually reversible. *Dapsone* - **Dapsone** is primarily known for causing **methemoglobinemia** and **hemolytic anemia**, especially in patients with G6PD deficiency. - While it can cause some dermatological side effects, **pigmentation** is not a characteristic feature, and it does not produce a "raindrop" pattern. *Minocycline* - **Minocycline** can cause various types of pigmentation, including **blue-gray discoloration** in scars, shins, and mucous membranes, as well as diffuse brown pigmentation. - However, the pigmentation caused by minocycline is typically diffuse or localized to specific areas, and it does not present as "raindrop pigmentation."
Forensic Medicine
2 questionsThe odour of cyanide is similar to?
What is the effect of strychnos nux vomica poisoning on a patient's consciousness?
NEET-PG 2012 - Forensic Medicine NEET-PG Practice Questions and MCQs
Question 771: The odour of cyanide is similar to?
- A. Rotten egg
- B. Fish
- C. Fruity
- D. Bitter almond (Correct Answer)
Explanation: ***Bitter almond*** - The classic description of **cyanide odor** is that of **bitter almonds**. This specific scent is a key indicator during forensic investigations or in cases of suspected poisoning. - However, not everyone can detect this smell due to a **genetic trait** that affects the ability to perceive it. *Rotten egg* - A **rotten egg** odor is characteristic of **hydrogen sulfide (H2S)**, a highly toxic gas. - This gas is often produced by the decomposition of organic matter and does not indicate cyanide exposure. *Fish* - A **fishy odor** is typically associated with compounds like **amines**, such as **trimethylamine**, which are found in decomposing fish or certain medical conditions like **trimethylaminuria**. - This smell is distinct from the bitter almond scent of cyanide. *Fruity* - A **fruity odor** can be associated with various substances, including **ketones** in conditions like **diabetic ketoacidosis** or certain **volatile organic compounds**. - This scent is not characteristic of cyanide poisoning.
Question 772: What is the effect of strychnos nux vomica poisoning on a patient's consciousness?
- A. Becomes unconscious within an hour
- B. Becomes unconscious only in severe cases
- C. Remains conscious throughout the poisoning (Correct Answer)
- D. Becomes unconscious immediately after exposure
Explanation: ***Remains conscious throughout the poisoning*** - Patients poisoned with **strychnine** (from *Strychnos nux vomica*) typically remain **fully conscious** and aware of their surroundings, even during severe convulsions. - This preservation of consciousness amidst intense muscular spasms is a **distinguishing and agonizing feature** of strychnine poisoning. *Becomes unconscious within an hour* - This statement is generally incorrect for strychnine poisoning, as the prominent feature is maintained consciousness alongside **neurological excitability**. - Loss of consciousness is not a **primary or direct effect** of strychnine, though severe complications could indirectly affect it. *Becomes unconscious only in severe cases* - While extreme metabolic derangements or secondary complications (e.g., severe hypoxia from prolonged seizures) might eventually lead to altered consciousness, the **direct pharmacological action** of strychnine does not cause unconsciousness. - The patient remains conscious even through the most severe and life-threatening **tetanic spasms**. *Becomes unconscious immediately after exposure* - Strychnine primarily acts as an **antagonist to glycine receptors** in the spinal cord and brainstem, leading to exaggerated reflexes and muscle overactivity, not immediate unconsciousness. - The onset of symptoms, including muscular spasms, typically occurs within **15-30 minutes** of exposure, with consciousness generally preserved.
Microbiology
2 questionsWhat is the correct order of application of reagents in the complete Gram staining procedure?
Which of the following statements about Haemophilus influenzae is true?
NEET-PG 2012 - Microbiology NEET-PG Practice Questions and MCQs
Question 771: What is the correct order of application of reagents in the complete Gram staining procedure?
- A. Gentian violet → Iodine → Alcohol/Acetone → Safranin (Correct Answer)
- B. Iodine → Gentian violet → Alcohol/Acetone → Safranin
- C. Safranin → Gentian violet → Iodine → Alcohol/Acetone
- D. Gentian violet → Alcohol/Acetone → Iodine → Safranin
Explanation: **Gentian violet → Iodine → Alcohol/Acetone → Safranin** - **Gentian violet** (or crystal violet) is the **primary stain** that colors all cells purple. - **Iodine** acts as a **mordant**, forming a crystal violet-iodine complex within the cell walls. - **Alcohol/Acetone** is the **decolorizer**, washing out the primary stain from Gram-negative cells but not from Gram-positive cells. - Finally, **Safranin** is the **counterstain** that stains decolorized Gram-negative cells pink or red. *Iodine → Gentian violet → Alcohol/Acetone → Safranin* - **Iodine** is a mordant and needs a primary stain (like gentian violet) to bind to and form a complex; applying it first would not effectively stain the cells. - The correct sequence requires the primary stain to be applied before the mordant can fix it. *Safranin → Gentian violet → Iodine → Alcohol/Acetone* - **Safranin** is a counterstain and should be applied last to stain the decolorized Gram-negative cells, not as the first reagent. - Applying reagents out of order would lead to incorrect staining results, as **safranin** is meant to provide contrast after decolorization. *Gentian violet → Alcohol/Acetone → Iodine → Safranin* - **Alcohol/Acetone** (decolorizer) is applied too early in this sequence; it should be used after the mordant (iodine) has formed a complex with the primary stain. - Applying the decolorizer before the mordant would prevent the formation of the crystal violet-iodine complex, leading to incorrect differentiation between Gram-positive and Gram-negative bacteria.
Question 772: Which of the following statements about Haemophilus influenzae is true?
- A. It is not capsulated
- B. Invasive strain causes severe diseases but is less common than non-invasive strains
- C. Encapsulated strains are the most common cause of severe H. influenzae diseases (Correct Answer)
- D. Typically grown on chocolate agar in CO2-enriched environment but not clinically relevant to severe diseases
Explanation: ***Encapsulated strains are the most common cause of severe H. influenzae diseases*** - **Encapsulated strains**, particularly **type b (Hib)**, are responsible for the majority of severe invasive H. influenzae infections including **meningitis**, **epiglottitis**, and **septicemia**. - While the Hib vaccine has dramatically reduced the incidence of type b disease, encapsulated strains remain the primary cause of severe H. influenzae infections when they occur. - Non-encapsulated (nontypeable) strains more commonly cause **mucosal infections** like otitis media and bronchitis, but rarely cause severe invasive disease. *It is not capsulated* - This is incorrect. H. influenzae exists in both **encapsulated** (types a-f) and **non-encapsulated (nontypeable)** forms. - The **encapsulated strains**, especially **type b**, are most virulent and cause severe invasive diseases. *Typically grown on chocolate agar in CO2-enriched environment but not clinically relevant to severe diseases* - While the growth requirements are correct (H. influenzae requires **X factor (hemin)** and **V factor (NAD+)** found in chocolate agar), the second part is completely false. - H. influenzae is highly clinically relevant and causes severe diseases including meningitis and epiglottitis. *Invasive strain causes severe diseases but is less common than non-invasive strains* - While this statement is epidemiologically true (nontypeable strains are more prevalent than encapsulated strains), it doesn't address which type causes severe diseases most commonly. - The question asks which statement is true, not which strain type is more prevalent in the general population.
Pharmacology
4 questionsWhich of the following drugs does not inhibit bacterial protein synthesis?
Sulphonamide injection causes decrease in folic acid by?
Which of the following is not used as treatment for lymphatic filariasis -
What is the antidote for Ethylene Glycol?
NEET-PG 2012 - Pharmacology NEET-PG Practice Questions and MCQs
Question 771: Which of the following drugs does not inhibit bacterial protein synthesis?
- A. Aminoglycosides
- B. Chloramphenicol
- C. Clindamycin
- D. Sulfonamides (Correct Answer)
Explanation: ***Sulfonamides*** - Sulfonamides do **NOT** inhibit bacterial protein synthesis; instead, they inhibit **folic acid synthesis**. - They act as **competitive inhibitors** of dihydropteroate synthase, an enzyme involved in the synthesis of dihydrofolic acid. - Folic acid is essential for nucleotide synthesis and DNA replication, making sulfonamides bacteriostatic agents that work through a completely different mechanism than protein synthesis inhibitors. *Aminoglycosides* - Aminoglycosides bind to the **30S ribosomal subunit**, causing misreading of mRNA and premature termination of protein synthesis. - This leads to the production of **abnormal and non-functional proteins**, ultimately killing the bacterial cell. *Chloramphenicol* - Chloramphenicol binds to the **50S ribosomal subunit**, thereby inhibiting the peptidyl transferase enzyme. - This prevents the formation of **peptide bonds** between amino acids, effectively blocking protein elongation. *Clindamycin* - Clindamycin also binds to the **50S ribosomal subunit**, specifically at the P-site. - It interferes with the **translocation step** of protein synthesis, preventing ribosomal movement along the mRNA.
Question 772: Sulphonamide injection causes decrease in folic acid by?
- A. Inhibition through competition with substrate (Correct Answer)
- B. Inhibition without competition
- C. Inhibition through a different site
- D. Inhibition that does not involve the active site
Explanation: ***Inhibition through competition with substrate***Sulphonamides are **structural analogs of p-aminobenzoic acid (PABA)**, a substrate crucial for dihydropteroate synthase [1, 2]. They competitively inhibit this enzyme, which synthesizes **dihydrofolic acid**, a precursor to **tetrahydrofolic acid (THF)**, thereby reducing folic acid production in bacteria [1, 2].*Inhibition without competition*This typically refers to **non-competitive inhibition**, where the inhibitor binds to an allosteric site and changes the enzyme's conformation, regardless of substrate concentration. Sulphonamides, however, specifically compete with PABA at the active site of **dihydropteroate synthase**.*Inhibition through a different site*This describes **allosteric inhibition** or non-competitive inhibition, where the inhibitor binds to a site other than the active site. Sulphonamides do not work through an allosteric mechanism; they directly interfere with the binding of PABA at the enzyme's active site.*Inhibition that does not involve the active site*This is another way to describe **non-competitive** or **allosteric inhibition**, where the inhibitor binds elsewhere on the enzyme, altering its function without directly blocking the active site. Sulphonamides' mechanism is distinct, as they closely resemble the natural substrate and directly compete for the active site of **dihydropteroate synthase**.
Question 773: Which of the following is not used as treatment for lymphatic filariasis -
- A. DEC
- B. Albendazole
- C. Ivermectin
- D. Praziquantel (Correct Answer)
Explanation: ***Praziquantel*** - **Praziquantel** is primarily an **anthelmintic drug** effective against **schistosomiasis** and **tapeworm infections**. - It does not have a significant role in the treatment of **lymphatic filariasis**. *Ivermectin* - **Ivermectin** is one of the **mainstays** of treatment for **lymphatic filariasis**, particularly in combination therapies. - It works by paralyzing and killing **microfilariae**, reducing their numbers in the bloodstream. *DEC* - **Diethylcarbamazine (DEC)** is a **highly effective antifilarial drug** used to kill both **microfilariae** and **adult worms** in lymphatic filariasis. - It is often used in mass drug administration programs and for individual treatment. *Albendazole* - **Albendazole** is an **anthelmintic drug** often used in combination with **Ivermectin** or **DEC** for the treatment of **lymphatic filariasis**. - It helps to kill **microfilariae** and has some macrofilaricidal effects, reducing the viability of adult worms.
Question 774: What is the antidote for Ethylene Glycol?
- A. Barbiturate
- B. Acetylcysteine
- C. Ferric chloride
- D. Fomepizole (Correct Answer)
Explanation: ***Fomepizole*** - **Fomepizole** is the primary and preferred antidote for ethylene glycol poisoning, as it competitively inhibits **alcohol dehydrogenase**, the enzyme responsible for metabolizing ethylene glycol into its toxic metabolites. - By blocking this enzyme, fomepizole prevents the formation of harmful compounds like **glycolic acid** and **oxalic acid**, which cause metabolic acidosis and kidney damage. - **Ethanol** is an alternative antidote that works by the same mechanism (competitive inhibition of alcohol dehydrogenase) and can be used when fomepizole is unavailable, though fomepizole is preferred due to better safety profile and easier dosing. *Barbiturate* - **Barbiturates** are a class of psychoactive drugs that act as central nervous system depressants, primarily used for sedation, anesthesia, and seizure control. - They have no role in neutralizing or metabolizing ethylene glycol or its toxic byproducts. *Acetylcysteine* - Acetylcysteine is an antidote primarily used for **acetaminophen (paracetamol) overdose**, where it replenishes glutathione stores and detoxifies its toxic metabolite, **NAPQI**. - It does not have any direct antidotal effect against ethylene glycol or its metabolites. *Ferric chloride* - **Ferric chloride** is a chemical compound used in various industrial processes, water treatment, and as a laboratory reagent. - It is highly corrosive and toxic if ingested, but it is not used as an antidote for any type of poisoning, including ethylene glycol.
Surgery
1 questionsWhich of the following actions is NOT recommended when dealing with a patient who has been bitten by a snake?
NEET-PG 2012 - Surgery NEET-PG Practice Questions and MCQs
Question 771: Which of the following actions is NOT recommended when dealing with a patient who has been bitten by a snake?
- A. Reassurance
- B. Immobilization of the affected limb
- C. Clean with soap and water
- D. Local incision (Correct Answer)
Explanation: ***Local incision*** - Making an incision at the bite site can **worsen tissue damage**, increase the risk of infection, and does not effectively remove venom. - This practice is **outdated** and potentially harmful, as venom spreads rapidly through the lymphatic system rather than being localized in a way that incision can help. - **Local incision is NOT recommended** and is a contraindicated first-aid measure. *Immobilization of the affected limb* - Immobilizing the bitten limb helps **slow the spread of venom** through the lymphatic system. - This is a **recommended first-aid measure**, especially for neurotoxic snakebites, and should be done by keeping the limb at or below heart level. - Proper immobilization involves splinting the limb without restricting blood flow. *Reassurance* - Overt fear and anxiety can lead to symptoms like **tachycardia** and **hypertension**, which can exacerbate the effects of the venom. - **Calming the patient** helps reduce the physiological stress response, which is crucial as panic can worsen the clinical picture. - Reassurance is a **recommended supportive measure**. *Clean with soap and water* - Cleaning the wound helps remove surface venom and **reduce the risk of secondary bacterial infection**. - This is a **recommended basic first-aid measure** that promotes wound hygiene without interfering with venom management.