practice

Explanation

The subclavian vein is a paired large vein, one on either side of the body, and runs under the clavicle and anterior to the artery of the same name (subclavian artery). Each subclavian vein is a continuation of the axillary vein and runs from the outer border of the first rib to the medial border of anterior scalene muscle. The subclavian vein follows the subclavian artery and is separated from the subclavian artery by the insertion of anterior scalene. Subclavian vein is anterior to anterior scalene muscle. Hence, it occupies the Antescalene space (Spatium antescalenium).

Subclavian artery lies in between the scalene muscles. So, it occupies the interscalene space (Spatium interscalenium).

Explanation

Enterokinase is a protease of the intestinal brush border that specifically cleaves the acidic propeptide from trypsinogen to yield active trypsin. This cleavage initiates a cascade of proteolytic reactions leading to the activation of many pancreatic zymogens.

Trypsin is an enzyme that helps us digest protein. In the small intestine, trypsin breaks down proteins, continuing the process of digestion that began in the stomach. It may also be referred to as a proteolytic enzyme, or proteinase. Trypsin is produced by the pancreas in an inactive form called trypsinogen.

Therefore, enterokinase deficiency can cause a disturbance of protein hydrolysis (protein digestion/breakdown).

Explanation

Pyruvate kinase deficiency is an autosomal recessive condition. Pyruvate Kinase deficiency - decreased ATP production - rigid red blood cells - hemolysis - hemolytic anemia.

Pyruvate kinase is an enzyme involved in glycolysis. The pyruvate kinase enzyme is required for conversion of phosphoenolpyruvate into pyruvate and produces ATP. This is the final step in Glycolysis which supplies erythrocytes with energy in the form of ATP for cell membrane stability. Lack of this enzyme, therefore, hinders the completion of the reaction with the effect being:

• Increase in the level of dangerous precursors;

• Decrease in a number of products such as pyruvate, ATP and lactate.

Pyruvate kinase is not involved in any of these other reactions listed - decarboxylation of amino acids, amino acid deamination, Anaerobic glycogenolysis.

Glycogenolysis is the breakdown of glycogen to glucose while Glycolysis is the breakdown of glucose to produce energy.

Pyruvate is involved in Gluconeogenesis (synthesis of glucose) but this process does not produce ATP. Instead, it uses up ATP.

Explanation

Vitamin E is a powerful antioxidant that helps repair damaged cells. You can find it in various foods or get it as a supplement. Vitamin E is the major lipid-soluble component in the cell antioxidant defence system and is exclusively obtained from the diet.

Vitamin E is a potent chain-breaking antioxidant that inhibits the production of reactive oxygen species molecules when fat undergoes oxidation and during the propagation of free radical reactions. It acts as the first line of defence against lipid peroxidation, protecting the cell membranes from free radical attack.

Antihemorrhagic: Vitamin K

Antidermatitic: Vitamin A (also involved with Night blindness)

Antiscorbutic: Vitamin C

Antineuritic: Vitamin B12

Explanation

Non-steroidal anti-inflammatory drugs including low-dose aspirin are some of the most commonly used medicines. They are associated with gastrointestinal mucosal injury. Before prescribing, it is important to assess the patient’s gastrointestinal risk factors such as age and history of peptic ulcers. 

A peptic ulcer is a defect in the upper gastrointestinal mucosa that extends through the muscularis mucosa into deeper layers of the gut wall. There are two major risk factors for peptic ulcer disease – Helicobacter pylori and non-steroidal anti-inflammatory drugs (NSAIDs). NSAIDs including low-dose aspirin are some of the most commonly used drugs. They have good efficacy and a long history of clinical use, but can cause peptic ulcers which may have fatal complications.

Explanation

Cells respond to DNA damage by instigating robust DNA damage response pathways, which allow sufficient time for specific DNA repair pathways to physically remove the damage in a substrate-dependent manner. At least five major DNA repair pathways—base excision repair (BER), nucleotide excision repair (NER), mismatch repair (MMR), homologous recombination (HR) and non-homologous end joining (NHEJ)—are active throughout different stages of the cell cycle, allowing the cells to repair the DNA damage. A few specific lesions can also be removed by direct chemical reversal and interstrand crosslink repair. These repair processes are key to maintaining genetic stability in cells.

Transcription is the process of copying a segment of DNA into RNA. In Translation, the RNA molecule created in the transcription process delivers information from the DNA to the protein-building machines which results in mature proteins.

DNA replication is the process by which a double-stranded DNA molecule is copied to produce two identical DNA molecules.

Reverse transcription is the enzyme-mediated synthesis of a DNA molecule from an RNA template. This is the reverse of normal transcription. (Transcription: RNA is made from DNA; Reverse transcription uses reverse transcriptase found in HIV to make DNA from RNA).

Explanation

Glutamine synthetase (GS) in the brain is located mainly in astrocytes. One of the primary roles of astrocytes is to protect neurons against excitotoxicity by taking up excess ammonia and glutamate and converting it into glutamine via the enzyme Glutamine synthetase.

Since ammonia freely crosses the blood-brain barrier (BBB) and astrocytes are responsible for maintaining the BBB, the presence of GS in the perivascular processes could produce a rapid glutamine synthesis to be released into blood. It could, therefore, prevent the entry of high amounts of ammonia from circulation to attenuate neurotoxicity.

Explanation

Mixed infection is defined as the simultaneous presence of at least two different pathogens, both contributing to an abnormal health status leading to clinical signs and symptoms. Mixed infection is where a single infection is caused by a variety of microorganisms (Influenza virus and Mycoplasma) which are simultaneously causing the same infection.

Autoinfection is an infection by a pathogenic agent already within the body or infection transferred from one part of the body to another. In short, the microorganism didn’t come from outside the body, its part of the normal oral microflora. So, it is a case of self-infection.

Superinfection: classic example is Hepatitis B patient superinfected by Hepatitis D.

Relapse is a case of deterioration in someone\'s state of health after a temporary improvement.

Iatrogenic infection is an infection after medical or surgical management, whether or not the patient was hospitalized.

Explanation

Nuclear submarines and aircraft carriers are powered by onboard nuclear reactors which emits varying degrees of radiation. Now, for a patient with bone marrow atrophy, anemia, leukopenia, lymphocytic disintegration etc., given the history of his occupation, this is consistent with Radiation Syndrome or Sickness.

Being exposed to a lot of radiation over a period of time, can lead to acute radiation syndrome (ARS, or "radiation sickness"). Low doses of ionizing radiation induce subtle but persistent immune function alterations and High doses are mainly immune suppressive.

The constellation of lymphocytic disintegration, leukopenia, anemia, bone marrow atrophy points to an immunosuppressive state.

Vibration disease most often has to do with using heavy machines like tractors, drilling equipment etc.

Acute anemia can occur on its own, but this will not explain leukopenia, lymphocytic disintegration found in this patient.

Decompression sickness often seen in divers and it has to do with gas embolism.

Acute leukemia will present with leukocytosis (increased leukocyte count) and not Leukopenia (decreased Leukocyte count) as seen in this patient.

Explanation

Glucocorticoids are steroid hormones that regulate multiple aspects of glucose homeostasis. Glucocorticoids promote gluconeogenesis in liver, whereas in skeletal muscle and white adipose tissue (WAT) they decrease glucose uptake and utilization by antagonizing insulin response. Therefore, excess glucocorticoid exposure causes hyperglycemia and insulin resistance. 

The gluconeogenic pathway generates glucose from non-carbohydrate substrates. Gluconeogenesis mainly occurs in the liver, though the kidney and intestine are also contributors. The major gluconeogenic precursors are lactate, glycerol and gluconeogenic amino acids, such as alanine.

Explanation

First of all, you can rule out all options that have hyperhydration.

The patient has been vomiting with profuse diarrhea, coupled with dry mucous membrane and decreased skin turgor - these are classic symptoms of dehydration.

Now, someone who is vomiting with diarrhea will lose electrolytes - hypoosmolar.

Therefore, we have a case of Hypoosmolar dehydration here.

Causes: hypoaldosteronism, continuous profuse sweating, recurrent or uncontrollable vomiting, profuse diarrhea just as the patient in question (for example, in enteritis, cholera or malabsorption syndrome) associated with the loss of intestinal juice containing K+, Na+, Ca2+ and other cations (loss of water - hypohydration; loss of ions - hypoosmolar).

Explanation

Systemic lupus erythematous (SLE) is a multisystemic disease in which there is production of autoantibodies and immune complexes formation. The antibodies can be directed against many nuclear antigens (Antinuclear antibody - ANA; Anti double stranded DNA - Anti-dsDNA). The immune complexes can be deposited or formed in diverse tissues, activating the complement and releasing proinflammatory cytokines that produce tissue damage.

On histopathology, some features are suggestive of lupus nephritis: hyaline thrombi and “wire loop” lesions (homogenous and “rigid” thickening of peripheral capillary loops due to subendothelial immune deposits), nevertheless, the only alteration considered by many authors as pathognomonic of lupus nephritis are the hematoxylin bodies: they are rounded, smudgy, lilac-staining structures, seen as cells with degenerated aspect; probably they represent degenerated nuclei and correspond to LE cells described in the blood of patients with SLE.

Explanation

Metronidazole (Flagyl), an antibiotic commonly used in treating intestinal infections. It is used in the treatment of susceptible anaerobic bacterial and protozoal infections in the following conditions: Amebiasis, symptomatic and asymptomatic trichomoniasis; surgical prophylaxis (colorectal) and as part of a multidrug regimen for H. pylori eradication to reduce the risk of duodenal ulcer recurrence. The most important antibiotics in H. pylori treatment are clarithromycin/amoxicillin; metronidazole, and a proton pump inhibitor such as omeprazole or lansoprazole.

Chingamin (Chloroquine) commonly used as an anti-malarial. Not effective against H. pylori.

Acyclovir - antiviral commonly used to treat Varicella Zoster (Chicken pox) Infections.

Doxycycline hydrochloride belongs to the Tetracycline class of antibiotics that inhibits synthesis of bacterial proteins. 

Isoniazid is an anti-tuberculosis medication.

Explanation

A close look at the image below clearly answers this question.

The right lung has 3 lobes: Superior; Middle and Inferior

The left lung has 2 lobes: Superior and Inferior.

Each of the lobes are subdivided into segments and from the image, we know that only the Right middle lobe has a medial and lateral segment (segmentum laterale et segmentum mediale).

Explanation

Calcium ions are responsible for the contraction of the heart. You know calcium helps the muscles contract forcefully and they are also needed for impulse conduction in the Sinoatrial (SA) and Atrioventricular (AV) nodes. Therefore, increased Calcium ions can both increase the cardiac contraction force and frequency (impulse transmission). Increasing contractility is done primarily through increasing the influx of calcium or maintaining higher calcium levels in the cytosol of cardiac myocytes during an action potential.

If the question asked about the effect of calcium antagonist, then decreased force and frequency of contraction would be the right answer.

Explanation

Potassium permanganate (KMnO4) is commercially prepared by mixing solution of potassium hydroxide (KOH) and powdered manganese oxide, with oxidizing agents like potassium chlorate. The mixture is boiled and evaporated and the residue is heated in iron pans until it has acquired a pasty consistency. It is odourless. An aqueous solution with a sweetish astringent taste. It is water-soluble and more soluble in boiling water.

This compound is used as a disinfectant to cure certain skin conditions like foot fungal infections, dermatitis. Another important application of potassium permanganate is in the treatment of bacterial infections. It is also used as a bleaching agent, as a pesticide, and as an antiseptic.

2KMnO4 + H2O = 2KOH + 2MnO2 + 3O2

Potassium permanganate liberates oxygen in atomic form.

Explanation

The veins have the three basic layers (tunica adventitia, tunica media and tunica intima).

Tunica Intima: A thin endothelial lining, (in some veins, you may be able to see the valves).

Tunica Media: This layer contains 2-3 layers of muscle cells.

Tunica Adventitia: This is the broadest layer. It contains longitudinal collagen fibres, and vasa vasorum.

From the question stem, the specimen being described consists of an endothelium and basement membrane (Tunica Intima); Loose connective tissue (Tunica adventitia). 

You can see that the Tunica Media which has muscle cells is absent in this specimen which makes it a NON-MUSCULAR VEIN.

Explanation

Syphilis is caused by Treponema pallidum. The microscopic findings described in this question is consistent with findings associated with Syphilitic granuloma.

The syphilis granuloma consists of a central area of fibrinoid or caseous necrosis surrounded by mononuclear inflammatory cells, mostly plasma cells, lymphocytes, epithelioid cells, and seldom giant Langhans cells. Surrounding it, is the granulation tissues, endovasculitis and perivasculitis.

Explanation

Vasopressin (arginine vasopressin, AVP; antidiuretic hormone, ADH) is a peptide hormone formed in the hypothalamus, then transported via axons to the posterior pituitary, which releases it into the blood. The hypothalamus of a dehydrated person releases antidiuretic hormone (ADH) through the posterior pituitary gland. ADH signals the kidneys to recover water from urine, effectively diluting the blood plasma.

Dehydration which leads to hyperosmolar states most strongly trigger its release. ADH primarily affects the ability of the kidney to reabsorb water; when present, ADH induces expression of water transport proteins in the late distal tubule and collecting duct of the kidney to increase water reabsorption. 

ADH promotes water reabsorption in the kidneys and, at high concentrations, will also cause vasoconstriction. These two mechanisms together serve to increase effective arterial blood volume and increase blood pressure to maintain tissue perfusion. It is also important to note that in states of dehydration (hypovolemia), ADH will be secreted even in hypoosmotic states. Conversely, hypervolemia inhibits ADH secretion; therefore, in hyperosmotic hypervolemic states, ADH secretion will be reduced.

Explanation

There are two main ligaments that are attached to the ovary directly - Ovarian ligament and the Suspensory ligament.

The ovarian ligament connects the uterus and ovary. The ovarian ligament (also called the utero-ovarian ligament or proper ovarian ligament) is a fibrous ligament that connects the ovary to the lateral surface of the uterus.

The suspensory ligament of the ovary (infundibular pelvic ligament) attaches the ovary to the pelvic sidewall and contains the ovarian blood vessels.

The broad ligament of the uterus is a double-layer fold of peritoneum that attaches the lateral portions of the uterus to the lateral pelvic sidewalls. The broad ligament is divided into the mesometrium (largest portion), the mesosalpinx (mesentery of the uterine [fallopian] tubes), and the mesovarium (connects the ovaries to the broad ligament). 

The round ligament originates at the uterine horns (the points at which the fallopian tubes enter the uterus), and attaches to the labia majora, passing through the inguinal canal.

The lateral umbilical ligaments are bilateral raised ridges of parietal peritoneum in the deep aspect of the anterior abdominal wall overlying the inferior epigastric artery.

Explanation

Hypertension is classified into two types:

- In 90-95% of all cases of hypertension, no cause can be established – such cases are called essential or idiopathic or primary.

- In only 5-10% of all cases of hypertension is any disease which may be associated with secondary hypertension e.g. Kidney diseases, pheochromocytoma etc.

The main clinical-morphological forms of essential hypertension affects various organs in the body.

Explanation

Hypotension is a decrease in systemic blood pressure below accepted low values. While there is not an accepted standard hypotensive value, pressures less than 90/60 are recognized as hypotensive. Hypotension is a relatively benign condition that is under-recognized mainly because it is typically asymptomatic. It only becomes a concern once pumping pressure is not sufficient to perfuse key organs with oxygenated blood.

From the question stem, there is an acute drop in blood pressure, body temperature and tachycardia which can be classified as a manifestation of Acute Hypotension.

Explanation

In a typical blood pressure reading, such as 120/80, the lower number is diastolic blood pressure. Blood pressure measurements are usually reported as two different numbers 120/80mmHg. The first number - 120 indicates the systolic blood pressure while the second number - 80 indicates diastolic blood pressure. 

Diastolic blood pressure measures the lowest blood pressure in the arteries. The lowest blood pressure occurs when the heart muscle relaxes between beats. Now, for the left ventricle to pump blood into the aorta, it therefore means, it must overcome the lowest blood pressure in the aorta which is the diastolic blood pressure.

So, for a patient with 120/65mmHg, blood ejection into the aorta can only occur when left ventricular pressure exceeds 65mmHg.

Explanation

Thiamine deficiency occurs where the diet consists mainly of milled white cereals, including polished rice, and wheat flour, all very poor sources of thiamine. Polished rice refers to rice which has been milled to remove the husk, bran, germ, and varying amounts of the nutrients contained in them, leaving a starch-rich grain.

Vitamin B1 deficiency is explained by the fact that thiamine is an essential cofactor for the enzyme pyruvate dehydrogenase that allows oxidation of pyruvate to acetyl CoA. This is a key step in the process that allows energy production, in the form of ATP, from glucose oxidation. In the absence of thiamine this reaction cannot proceed and instead, pyruvate accumulates. 

Pyruvate dehydrogenase (PDH) is a key mitochondrial enzyme responsible for the conversion of pyruvate to acetyl-CoA and the enzyme is therefore essential in facilitating aerobic metabolism. Thiamine, or vitamin B1, is a crucial cofactor for pyruvate dehydrogenase. In the absence of thiamine, the conversion of pyruvate to acetyl-CoA is inhibited and lactate is produced.

In acute deficiency, pyruvate accumulates and is metabolized to lactate, and chronic deficiency may cause polyneuropathy and Wernicke encephalopathy. 

Increased methylmalonic acid - Vit. B12 deficiency

Increased Phenylpyruvate - Phenylketonuria

Increased Uric acid - Hyperuricemia

Explanation

Polycyclic aromatic hydrocarbons (PAHs) are a class of chemicals that occur naturally in coal, crude oil, and gasoline. They also are produced when coal, oil, gas, wood, garbage, and tobacco are burned.

PAHs are a class of widely spread mutagenic and tumorigenic environmental contaminants. Evidence indicates that mixtures of PAHs are carcinogenic to humans. The evidence comes primarily from occupational studies of workers exposed to mixtures containing PAHs. Such long-term studies have shown an increased risk of predominantly skin and lung as well as bladder and gastrointestinal cancers.

Explanation

Flexor digitorum superficialis is the largest muscle of the anterior compartment of the forearm. It belongs to the superficial flexors of the forearm, together with pronator teres, flexor carpi radialis, flexor carpi ulnaris and palmaris longus.

Based on its origin sites, flexor digitorum superficialis is divided into two heads; a humeroulnar head and radial head. Its large muscular belly courses distally towards the wrist, where it splits into four tendons and attaches to the middle phalanges of the second through fifth digits of the hand. Due to their superficial location, these tendons can be easily palpated on the distal part of the forearm. 

The main action of this muscle is flexion of the digits 2-5 at both the metacarpophalangeal and proximal interphalangeal joints.

Origin	Humeroulnar head: Medial epicondyle of humerus, coronoid process of ulna Radial head: Proximal half of anterior border of radius
Insertion	Sides of middle phalanges of digits 2-5
Action	Metacarpophalangeal and proximal interphalangeal joints 2-5: Finger flexion
Innervation	Median nerve (C8, T1)
Blood supply	Ulnar artery, radial artery, median artery

Explanation

5-Fluorouracil (5-FU) is still a widely used anticancer drug. Fluorouracil is a fluorinated pyrimidine that becomes phosphorylated intracellularly and then binds covalently with thymidylate synthetase, thereby inhibiting its action and interfering with DNA and RNA synthesis. 5-FU acts in several ways, but principally as a thymidylate synthase (TS) inhibitor. Interrupting the action of this enzyme blocks synthesis of the pyrimidine thymidylate (dTMP), which is a nucleotide required for DNA synthesis.

5-FU is converted to fluorodeoxyuridine monophosphate (FdUMP), which forms a stable complex with thymidylate synthase, and thus inhibits deoxythymidine mono-phosphate (dTMP) production. dTMP is essential for DNA replication and repair and its depletion therefore causes cytotoxicity and eventual cell death.

Explanation

I strongly believe that this question is a giveaway...

Acetone breath odor and Ketone bodies present in a comatose patient with Diabetes mellitus is consistent with Ketoacidotic coma.

Diabetic ketoacidosis (DKA) is a serious condition that can lead to diabetic coma (passing out for a long time) or even death. When your cells don't get the glucose they need for energy, your body begins to burn fat for energy, which produces ketones. Ketones are chemicals that the body creates when it breaks down fat to use for energy. The body does this when it doesn’t have enough insulin to use glucose, the body’s normal source of energy. When ketones build up in the blood, they make it more acidic - Ketoacidosis. They are a warning sign that the diabetes is getting out of control. Difficulty breathing, fruity breath odor, frequent urination and excessive thirst, hyperglycemia, presence of ketone in urine (ketonuria) are some of the common signs and symptoms.

Explanation

Fibroadenomas are common benign lesions of the breast that usually present as a single breast mass in young women. It presents as a mobile lump in the breast of young women.  Macroscopically, fibroadenomas are typically 1-5 cm in diameter, appearing as firm with clear margins, rubbery, well circumscribed, elastic consistency, glistening, greyish-white cut surface. It is composed majorly of fibrous tissue stroma and oftentimes glands. Fibroadenomas are stimulated by estrogen and progesterone, and by lactation during pregnancy, and they undergo atrophic changes in menopause.

From the question stem, the fibrous tissue tumor is found growing around a small canaliculi. So, it is safe to say it is a Pericanalicular Fibroadenoma.

Sarcoma, Cancer, Adenocarcinoma are malignant in nature and will not have clear margins on histology.

Explanation

Bacillus anthracis, the etiological agent of anthrax, is a Gram-positive bacterium capable of forming endospores when vegetative cells are deprived of an essential nutrient. Bacillus anthracis is a major biological warfare threat. The inhalation form of infection can kill quickly. While antibiotic treatment is effective, if diagnosis is delayed, the rapidly produced toxin may already be present in lethal amounts.

Anthrax toxins are secreted early in the course of disease prior to detectable bacteremia or immune response and therefore detecting this toxin in serum provide a more timely diagnosis compared to serology or culture dependent methodologies. That is why a more rapid and sensitive diagnostic method is used - Anti-anthrax fluorescent serum meant to quickly detect antibodies to the anthrax spores.

Toxins are produced very early once anthrax infects its host, so a rapid diagnostic test will be directed at detecting this toxin which is the goal of this diagnostic test - Anti-anthrax fluorescent serum.

Monoclonal antibodies to anthrax causative agents: this method is not as rapid as using Anti-anthrax fluorescent serum in which antibodies are directed at the anthrax toxin.

Anti-anthrax immunoglobulin - used for treatment, not diagnosis.