This boy has achondroplasia, which is caused by an autosomal dominant mutation in Fibroblast Growth Factor Receptor 3. FGF signaling is needed for proper cartilage function, and without it, the long bones of the body will not grow because the growth plate (made of chondrocytes) does not function. However, bones that undergo membranous ossification, like the bones of the head, will grow normally. This results in the patient having short extremities with a normal size trunk and large head relative to the limbs.

The patient seems to have an infection due to their elevated temperature and abnormal chest X-ray. However, their leukocyte count is low. In addition, the patient has hepatitis C, which is often associated with similar transmission routes to HIV, like intravenous drug use.

Vincristine is a chemotherapeutic drug that stabilizes microtubules and prevents them from disassembling. The cell in the picture is stuck in anaphase, with microtubules attached to its chromosomes, unable to pull them apart because it cannot disassemble its microtubules.

Question is basically asking what are the substrates used the first step in heme synthesis. In that step, glycine and succinyl CoA are combined to make aminolevulinic acid.

HMG CoA Reductase inhibitors prevent the liver from synthesizing its own cholesterol. In order to maintain its need for cholesterol, the liver has no choice by to increase its LDL receptor expression in order to take cholesterol from the blood.

The "likelihood of missing an association" refers to Type II error. The risk of Type II error is represented by beta. This could be confused with power, which is 1 - beta.

Specificity is equal to the number of true negative tests over the number of true negatives plus false positives:

Spec = TN /(TN + FP)

This patient shows signs of cirrhosis, which is likely associated with portal hypertension. Portal hypertension will cause increased pressure in all veins draining into the portal vein, and can cause bulging of these veins at areas where they meet those that drain to the vena cava. One area is the rectum and anus, where the superior rectal vein (from the portal system) meets up with the middle and inferior rectal veins (which drain to the caval system). Increased pressure in the superior rectal vein will cause hemorrhoids at this location.

In SIADH, the excessive ADH causes the collecting duct of the kidney to reabsorb huge amounts of water that it should normally excrete. That means that the plasma will now have much more water relative to solute (low osmolality) and the urine will have much more salt relative to water (higher osmolality).

The most important ethical principle that supersedes all others is autonomy. From an ethical standpoint, this patient has the right to refuse further treatment as he is mentally competent, in this case in the form of having the respiratory removed. From a legal standpoint, the physician is allowed to discontinue treatment for a patient if that is what the patient wants. This is different from situations of physician assisted suicide, which is more complicated and has variable ethics and legality.

All of the features described of this patient would be expected of a 68-year-old man. Shorter, less intense orgasms, as well as increased time needed between sex could be related to a slight drop in testosterone with age. However, he continues to grow hair well (feet and toes), implying that he hasn't dramatically lost testosterone production. His prostate is slightly enlarged, which could imply benign prostatic hyperplasia, but this should not directly impact his sexual function.

The patient in this question has cluster headaches. These headaches can be differentiated from migraines and tension headaches, as they tend to come in episodes across several years, with absent periods in between. Cluster headaches are often described as excruciatingly painful (sometimes called "suicide headaches").

Misoprostol is a prostaglandin analog (PGE2) that acts on the stomach to promote mucus protection of the stomach lining, but also acts in the uterus to encourage contraction, which makes it useful for abortion.

This girl has malignant hyperthermia, a dangerous adverse effect of some anesthestic agents characterized by sudden high fever and rhabdomyolysis. The only drug among this list that can cause malignant hyperthermia is succinylcholine. The other drugs that cause malignant hyperthermia are the halonated gases (flurane, sevoflurane, etc.), but nitrous oxide does not cause it.

HMG CoA reductase inhibitors block the ability of the body to produce its own cholesterol. The liver, unable to make its own cholesterol and still needing to do its job of making lipoproteins, needs to get it from somewhere. So, the liver increases expression of LDL receptors to take more LDL out of the blood for repackaging.

The jaw pain and headaches in an older woman are worrisome for Temporal Arteritis. This is a vasculitis, which could be best identified by determining the erythrocyte sedimentation rate.

The patient needs medical attention immediately, which eliminates obtaining a court order, or transferring her. A nurse does not have the same training and qualifications as a physician, so it would be inappropriate to ask them to examine the patient. Asking the hospital chaplain again could be inappropriate, and would take more time. Therefore, the best option among those given is to ask the patient if she will allow with her husband present.

This girl has chronic granulomatous disease, in which the immune system cannot properly form reactive oxygen species needed to kill phagocytosed organisms. This is especially bad when dealing with catalase positive organisms (like Staph), because these organisms already use catalase to break down reactive oxygen species. The most common cause of this condition is a mutation in NADPH oxidase, responsible for the generation of the superoxide radical.

Tetrodotoxin, found in puffer fish, inhibits sodium channels. This prevents depolarization of cardiac muscle and neurons, which leads to death if consumed in high enough quantity. The symptoms are vague (nausea, diarrhea, paresthesia), so questions will need to give some form of history about eating at a Japanese restaurant or eating pufferfish to give you a big hint. There is unfortunately not treatment.

Case series is a study in which the researchers present the history and treatment of a small group of similar patients, without describing any sorting into groups or randomization.

This boy has meningitis caused by Strep pneumoniae, the most common cause of infectious meningitis in general. The vaccine for Strep pneumo is a polysaccharide protein conjugate vaccine. The other major bacteria with a vaccine like this is H. influenzae.

Competitive inhibitors increase the Km of the substrate. The Km represents how easily a substrate can bind the active site, with a lower Km representing easy binding, and a higher Km meaning more difficult. If you add a competitive inhibitor, like ethanol in this case, it makes it more difficult for the methanol to bind the active site, because it must compete with the ethanol.

Dysmetria is the lack of coordination of intended movements. Normally these movements are coordinated by the cerebellum. This is located specifically on the man's right side, not both sides, so only one lobe will be injured.

This woman has a lot of signs that point toward an intestinal parasitic infection: recent travel to Papua New Guinea, cough and alveolar infiltrates, high eosinophil count, and a stool sample that has a worm in it. Most likely the patient has a Strongyloides infection, as this is the intestinal parasite that shows larva on stool sample. Basically all intestinal parasites can be treated with Bendazole drugs, such as Thiabendazole. Praziquantel would be more appropriate for a worm or liver fluke infection.

The patient states that she does not want a hormonal form of birth control. So, the question is really asking which of the non-hormonal options is most effective. The tricky part here, I think, is that the question makes you want to not pick IUD, because many IUDs are hormonally based. However, a non-hormonal IUD, like a copper IUD, is still more effective than the other options listed.

This girl has Mono caused by Epstein-Barr Virus. The symptoms are relatively vague, but lymphadenopathy like this would be common for Mono. The CBC shows elevated lymphocytes, implying this is not a bacterial illness, so viral is likely. Combined with the lymphadenopathy, this makes us worry about Mono. The Mono-Spot test for EBV is what the question is referring to when describing the sheep erythrocytes agglutinating. From there, this question requires that you know that in EBV infection, EBV infects B cells, but does not cause them to become abnormal. Instead, CD8 cells, which are actively trying to kill the B cells, become abnormal.

All HOX genes are transcription factors that help regulate body layout and different expression of genes for each body segment.

This question only concerns women in the 50-54 age group. The group has a mean of 246 and standard deviation of 50. Therefore, all those with values greater than 296 are all those above one standard deviation. 2/3 of all values on a normal distribution are within one standard deviation in either direction. Therefore, 1/3 are outside of this in either direction, meaning 1/3 of women have a value less than 196 or greater than 296. If we split that in half to only choose those greater than 296, we get 1/6 women, which is about 16%.

This patient has a gallstone lodged in the common bile duct. Therefore, the markers most likely to be elevated is something from the biliary tract, the best of which is alkaline phosphatase. There could potentially be elevations in AST and ALT, but this is not the MOST likely answer. Unconjugated bilirubin is not a good answer, because the liver can still conjugate all bilirubin, it just has issues now excreting that conjugated form. So the woman's CONJUGATED bilirubin is more likely to be elevated.

Avoidant personality disorder is characterized by a desire for social relationships, but a fear of being rejected or feeling inadequate for others. This is different from Schizoid, because Schizoid individuals do not desire relationships with others, and want to remain alone. The trickiest differentiation might be between Avoidant and Schizotypal, but Schizotypal individuals tend to remain isolated because of odd thinking, or "magical beliefs".