First question : They tell us its a lymphocytic leukemia
Second question : Deciphering whether it is a B cell or T cell.
The cells have no surface bound Ig M ,Ig G or cytoplasmic chains for these antibodies , but have a rearranged gene segment( meaning active ) for the T cell Receptor . So the Cells are T Cells
Third question : Now that we know that they are T Cells , we want to know whether they are CD4 or CD 8 positive
The cells in the clinical vignette lack both CD4 and CD 8 ( double negative )
According to how T cells normally develop - They start of as being double negative ( i.e not expressing CD4 or CD 8) in the subcapsular region and progressively become
- positive for both CD 4 and CD 8 in the cortex
- and eventually acquire the TCR and CD3 by the time they get to the medulla
These cells therefore must T lymphocyte thymocytes localised to the cortex
Here is my take: a ventricular septal defect in infancy allows for left to right shunting of blood in the ventricles. This causes an increased pressure in the right ventricle (due to more blood being pushed into it) and a decreased pressure in the left ventricle. Because there is more blood in the pulmonary circulation from the shunt, I think the left atrial pressure would also be increased in an early VSD.
SO when you repair the VSD, the left ventricle pressure will be increased compared to when the shunt was present (it is no longer losing blood), the right ventricle pressure will be decreased (it is no longer getting blood from the shunt), and the left atrial pressure will be decreased (there is no longer overload of the pulmonary system returning to the left atrium).
Deoxyhemoglobin has a higher pKa than oxyhemaglobin and thus will accept hydrogen ions more readily. This is important in the ability to "carry" CO2 as the main mechanism of CO2 transport is actually conversion of CO2 to HCO3- (CO2 + H2O -> HCO3- + H+), thus deoxyhemaglobin carries the H+ while HCO3- is transported in the plasma to the lungs. Carbaminohemaglobin is actually only about 20% of the CO2 trasnport and CO2 dissolved as CO2 is 10%; trasnport as HCO3- is around 70% of the CO2 transport.
Another important aspect of the process to take note of that they like to ask about is the chloride shift. Chloride moves the opposite direction as HCO3- in the RBC. Thus at tissues where we are generating HCO3- from CO2 and need to pump it out of the cell, chloride moves into the cell.At the alveoli where we need to pump HCO3- back into the RBC to turn it into CO2, chloride moves out of the cell.
The description points to pancreatic insufficiency due to steatorrhea (fat in the stool, likely due to insufficiency of pancreatic lipase) and muscle fiber in the stool (which points to incomplete protein digestion, likely due to insufficiency of pancreatic proteases).
Further, he has no deficiency in carbohydrate absorption as evidenced by the D-xylose test (which indicates an intact mucosa for absorption and does not require digestive enzymes, FA2020 p373); and he has no abnormalities on biopsy of the intestine.
Thus, the primary issue is pancreatic insufficiency and supplementation of pancreatic enzymes is most helpful.
NFKB is in its inactive state bound to IKB. As a part of the classical pathway, bacterial antigens bind to TLR and activate IKB kinase, (kinase phosphorylates)
IKB is ubiquinated and degraded
NFKB enters nucleus and synthesises the inflammatory stuff
Uw QID: 11955
First step is to make the presumptive diagnosis of osteoporosis from the clinical vignette . ( The supposed subtype in our patient is postmenopausal osteoporosis)
After this the next step is to make an association with the lab findings The primary defect is a deficiency of estrogen . Normally estrogen decreases osteoclast activity by
Net effect of losing estrogen is increased osteoclast activity ,and in this question by extension RANK L concentration .
NOTE : ALP which is an indicator of osteoblast activity does not change/ increase in osteoporosis , as such avoid all options with an increase in osteoblast activity
FA2020 p 612 has early fetal development. Here are the explanations for the answers:
Basically, even without knowing all the exact days of development, most answers can be eliminated based on having the events in the incorrect order or having an incorrect aspect about development (i.e. the syncytiotrophoblast forms concurrent with the cytotrophobast, 3 germ layers are present after gastrulation, the embryo is never truly resistant to teratogens after implantation, the sclerotome forms from somites so somites have to come first).
I definitely did not know this, but apparently smoking can worsen GERD due to tendency of nicotine to cause relaxation of the lower esophageal sphincter. Smoking is also linked to stomach ulcers due to interference with gastric mucosa and acid production. Just don't smoke kids. Don't do drugs. Stay in school forever like med students.
A note to self : Creatine phosphate is a short term energy source in muscle . Acts by donating phosphate groups to regenerate ATP .
*Creatine is derived from Arginine and metabolised to Creatinine ( which is excreted by the kidneys )
This is likely Herpes Simplex Virus 1 (based on the vesicular lesions on the lip) which remains dormant in sensory ganglia, most commonly the trigeminal ganglion (FA2020 p164).
Important aspects of volatile (gas) anesthetics: (FA2020 p549):
Here, we want to know loading dose which is equal to the volume of distribution x target concentration in plasma.
So our loading dose = 1.81L/kg x 10mg = 18.1mg/kg
She is a 55kg person so 18.1mg/kg x 55kg = 995.5 mg which approximates to 1000mg total loading dose.
Uterine atony is the most common cause postpartum hemorrhage due to failure of the uterus to effectively contract and retract after delivery. It is treated with uterine massage and oxytocin.
Botulism toxin acts via proteases that cleave SNARE and prevent acetylcholine release at the neuromuscular junction (FA2020 p132). Thus, it does not directly affect the post-synatpric muscle cell. If you add external acetylcholine, you would still have a completely normal response. This eliminates all but two answers.
The end plate potential (EPP) would be affected by botulism toxin because the end plate potential is the change in voltage that occurs at the postsynaptic muscle motor endplate after an action potential in the motor neuron axon triggers release of many acetylcholine vesicles. Normally, an action potential in the motor neuron will cause influx of calcium that leads to fusion of Ach vesicles (requiring SNARE) and exocytosis, releasing large quantities of Ach into the synapse which can then bind and trigger an EPP in the muscle. With botulism, fusion of the Ach vesicles is inhibited so less Ach is released and the EPP is blunted. Notably, the voltage is the same as the mEPP which is the voltage after random occurrence of Ach release (see below).
A miniature end plate potential (mEPP) is the voltage change that occurs when one vesicle of acetylcholine is released. These occur randomly. mEPP would not be affected by botulism toxin because it is the produce of random fusion of a vesicle which could still occur after administration of botulism toxin.
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nmyoPrula eaedm illw retnefeir hiwt gsa exeanchg igelnad ot hpeioaxym.
The primary mechanism of inflammation "tumor" or swelling is increased permeability of the endothelium which leads to leakage of fluids (FA2020 p213)
Mixed venous O2 content 8 vol% (N=10%–16%)
A) Anemia - Patient has nl PaO2 and decreased O2 content. Also patient is hyperventilating and CO2 is thus low.
Anemia causes hypoxia without hypoxemia. Meaning low O2 delivery to tissues but not low O2 saturation of the blood. The lungs can adequately deliver O2 to the arterials so PaO2 is normal. Anemia causes low O2 content because you have relatively low amounts of Hb to carry oxygen.
O2 content = (1.34 × Hb × Sao2) + (0.003 × Pao2)
Based on the history (consumption of large amounts of alcohol and elevated serum amylase/lipase with hypocalcemia), this man likely has acute pancreatitis (FA2020 p397). One of the major complications is autodigestion of tissues, such as what is seen in the image.
Lentigo maligna is a type of melanoma (FA2020 p484), hence why it is important the lesion is brown/black with irregular borders and enlarging (all hallmarks of melanoma). The biopsy description also fits lentigo maligna, but even if you are not a pathologist the description that fits cancer and and "atypical melanocytes" should point you to lentigo maligna.
FA2020 p482, 477 and 484
This man likely has diabetic neuropathy and thus would have neuropathic pain. Neuropathic pain is described as a burning pain as compared to the other kinds of pain.
He has a donw nad tou ip,ulp eadusc yb CN III syal.p isH agez si due ot depnouspo nctioa of the traalel rutecs dna iorpesur ;bieuqol psitos eud to aienetdnorv fo tvraleo praeeplab iri.esupsos
eTh ylon jyuinr lsetdi htat udlco scaeu a CN III slpay is rseaynmu of teh CAP mpgsneroics the ruromtaolco nlscue.u
She sah morto nad syesnor ymsps.tom ihsT r/o thbo ksdni fo psmeil. rHe rseieuzs ear tno secbdidre sa onccnlit/oci eeosnvmmt, adn cdleuin dprioes of iaidprme scnseoino.susc Tish erslu tuo lgnaezeeidr nccoiictl./no eThre is a lco-tiatsp ,ttaes ahtt rselu uto .caebsen
Aslo the lip csnmakgi is eacttrahcsicri fo imsm,atuaot wchih si odfnu in eclopmx aaitplr iuszsree
An USMLE testable fact about salmonella species is that antibiotic use actually prolongs the excretion of the organism. Fun fact(?) for memorization as there is no clear answer as to why that I could find.
I don't like this question for many reasons, but basically he has sarcoidosis (noncaseating granulomas with no pathogen found on biopsy) which according to First Aid is more common in African-American females. Since he is African-American that is his risk factor (FA2020 p676).
In hypothesis testing, the alpha value is the probability of making a Type I error. This is the type of error mentioned in the question.
In this study, a placebo is not used on the control group. The experimental group gets dextromethorphan while the control group gets "no treatment". This results in procedure bias, as subjects in different groups are not treated the same. Blinding and use of a placebo reduce the influence of participants and researchers on procedures and interpretation of outcomes as neither are aware of group assignments.
See table on bias and study errors in FA 2019 p 260.
TL;DR: Even with Type I or II renal tubular acidosis the ammoniagenesis from glutamine is not impaired and thus is the main source of ammonia.
Here is my take: Based on her history and measured plasma values, this girl likely has one of the "low potassium" renal tubular acidoses, either Type I or Type II (see this chart for reasoning based on measured values or this image for fun colorful renal tubular acidosis and FA2020 p593)
Then, we are told that she has a defect in "ammoniagenesis". In the renal tubules, ammonia is generated in two primary ways: via direct conversion of glutamine to ammonia in the proximal tubule which is then secreted into the tubule, or by NH3 combining with with H+ in the collecting tubules (which I guess they are considering a separate ammoniagenesis pathway even though its all kinda related?). See this diagram or this diagram
Assuming our girl has Type I renal tubular acidosis, there will be decreased availability of hydrogen ions in the renal tubules to combine with NH3. Thus, the primary source of ammonia production in this patient will be glutamine (which is the major source of ammoniagenesis in a normal person anyways).
Further reasoning - Type I is impaired secretion of hydrogen ions into the lumen, so there will be less hydrogen ions available. She likely has type I because this is primarily treated with potassium citrate (both to buffer and to prevent renal stones which are a common complication). Even if she had Type II the increased excretion of bicarb would also buffer more H+ leaving less for ammoniagenesis in the NH3/H+ combination fashion.
Contrarily, Type 4 renal tubular acidosis (hyperkalemic) results in decreased synthesis of ammonia in the proximal tubules, which we know she does not have because of her low potassium.
Key aspects of the question:
Increase in oxygen consumption is the normal response to exercise and alone is not pathologic. Extravascular compression of the coronary arteries is also considered normal and nonpathologic; this is why most coronary blood flow occurs during diastole and why the endocardium is most susceptible to ischemia.
This woman has the classic signs of vitamin C deficiency, or scurvy: easy bruising, petichiae, perifollicular hemorrhages, gum disease, and slow wound healing. Vitamin C is necessary for proper hydroxylation of proline and lysine in collagen. (FA2020 p69 [nice])
Immunohistochemistry uses fluorescently tagged antibodies to bind specific antigens on tissues. In this case, an antibody could be directed against CD44v10 variant protein used to tag the cells in the samples that express the variant. This is also useful because it can be done on slides of paraffin embedded tissue.
The burnt almond smell and noncyanotic dyspnea is characteristic of cyanid poisoning. Cyanide poisoning is treated with nitrites because nitrites oxidize hemoglobin to form methamoglobin which binds cyanide, allowing less toxicity. Thiosulfate is often added to increase renal excretion as thiocyanate. Cyanide toxicity may also be treated with hydroxycobalmin, which binds cyanide.
FA2020 p667 has differentiation of cyanide from CO poisoning.
Tuberous sclerosis is characterized by HAMARTOMASS [Hamartomas in CNS and skin, Angiofibromas , Mitral regurgitation, Ash-leaf spots , cardiac Rhabdomyoma, (Tuberous sclerosis), autosomal dOminant; Mental retardation (intellectual disability), renal Angiomyolipoma , Seizures, Shagreen patches, FA2020 p525]
If you didn't know what hamartomas look like (i.e. me), here is a picture of what they were describing. They also describe seizures, subependymal calcified nodules (likely hamartomas of the CNS), and a cardiac mass, which is likely a rhabdomyoma. These are characteristic of Tuberous Sclerosis.
Wrong answer explanations:
Note: IL-12 receptor deficiency, or a defect in the Interferon Gamma receptor
Think Disseminated Mycobacterial and Fungal Infections . Also salmonella *
This woman's cardiac arrest caused a period of loss of blood flow and ischemia in the kidney that has led to acute tubular necrosis. In ATN there is an inciting event then an oliguric phase. In ATN, there is death of renal tubular epithelial cells that slough off and form muddy brown granular casts. Keep in mind the proximal tubule and thick ascending limb are the part of the kidney most susceptible to hypoxic injury. [FA2020 p602]
siclcsa aahstnieym gvirsa .tupicre sWrnseo ithw u.se xS ilnudec p.adolipi mormIvpente ihwt .hACE
olsA ides to,ne 'dnto ucfos on hte ygcepnnra assut,t but mneow woh rae in eth uttrppsamo iorde aer ta taarrulyiplc hghi kris of evipnoedgl maentysaih viarsg
sThi qsiunoet si nkgisa waht eftl nitmdnao ltcricanuio m.esan I sepupos ti wtnas su ot fneir thta het ADP si pgsipyunl hte dimhpagra eacsfru dan VA nd.eo
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lsAo the VA dnoe si dlpspiue yb eht natvcreuliorAtri ndoal ,etayrr hwich nac eb a brnahc ffo fo het CAL ro eht XtbuCL otn eayllr the ADP
os ciugnnfos ueisqont for em but the tpnio is ot nwko het surceo of flet dmoitnan iurtcnoailc ot eht APD
Lipopolysaccharide, or LPS, is the primary endotoxin mediator of gram(-) sepsis leading to septic shock. This woman likely has sepsis from E. coli, a gram negative bacterium which produces LPS, based on her history indicating a UTI. E.coli are the most common cause of UTI. (FA2020 p133)
Based on the question stem and the autoanitbodies given (butterfly rash combined with anti-dsDNA/anti-Sm/antiphospholipid), this woman has classic lupus. SLE is associated with cytopenias, so thrombocytopenia is the best choice of the available answers. Thrombocytopenia is common in lupus (FA2020 p470)
From what I can tell, the gist of this question is that he has SCID and since the SCID child has basically no immune system (particularly because the lack of T-cell immunity) there is a higher chance of transfusion-associated graft versus host disease (TA-GVHD) so blood products have to be irradiated.
This woman has Polycystic ovarian syndrome. This can be deduced because of the high LH:FSH ratio (>2), high BMI, and presence of withdrawal bleeding in a progesterone withdrawal test. In polycystic ovarian syndrome, there is increased release of androgens from theca interna cells. These androgens can cause symtoms commonly associated with PCOS (hirsutism, acne) but can also be aromatized to estrogen in adipose tissue. The presence of estrogens in this form causes constant negative feedback on the hypothalamus and dysregulation in the appropriate levels of the gonadotropins (see here and here)
A progesterone withdrawal test is used to help determine the cause of amenhorria. If withdaral bleeding occurs, it means the patient has sufficient estradiol and the amenorrhia is due to anovulation. If no withdrawal bleeding occurs, it means the patient either has chronic anovulation without estrogen, a nonreactive endometrium, or a problem with uterine outflow. In our patient's case, she has withdrawal bleeding so she has anovulation, a common symptom of polycystic ovarian syndrome.
This is left homonomous hemianopia, which is caused by lesion to the contralateral optic tract (D). This occurs because the nasal retinal fibers (temporal visual field) cross at the optic chiasm while the temporal retinal fibers (nasal visual field) do not. See FA2020 p542 or here for image.
Lesion of the optic nerve (A or C) would cause complete blindness in either eye.
Lesion of the optic chiasm (B) causes bitemporal hemianopia.
Lesion to the left optic tract (E) would cause right homonomous hemianopia.
This woman has a carcinoid tumor, associated with carcinoid syndrome characterized by flushing, wheezing, and diarrhea. (FA2020 p 352) Based on her CXR I'd say she probably has a bronchial carcinoid tumor. Tumor cells would be chromogranin(+).
Carcinoid syndrome is a paraneoplastic syndrome caused by secretion of serotonin (5-HT). It is treated with a somatostatin analog like octreotide and the presence of 5-HIAA in the urine can be a marker (5-HIAA is a serotonin breakdown product).
This is a partial mole because of the presence of fetal parts. Complete moles have no fetal parts, partial moles have fetal parts(PARTial = fetal PARTs). (FA2020 p642)
Oseltamivir and zanamivir are influenza neuraminidase inhibitors. Typically, neuraminidase allows influenza particles to bud off host cells. Without the functioning enzyme, the virion buds cannot detach from the host cell membrane.
The uneven distribution of ADHD based on gender(more cases of ADHD among boys ) is a potential confounder , and so STRATIFICATION addresses this
Although botulism blocks ACh release, it wouldn't have effects on mpp and the response to exogenous ACh provided to the synaptic junction. The potentials would be the same as it would normally be. The epp difference was disclaimed in the question stem.
iltsva dna nede to be rdtetae fs,itr so iontreap and neht mdiiploaerx.
partionmt ot eotn atth saahohopgtrnoeps ecmoeb vresrieblrie at a tricnea ioptn os imoplaedxri seod lstli eden ot be eivng eyrla
TLC ecaeddrse egssgust vtrsrectiei eseaid.s telicaruR pattner sugtssge rplyamuon iisofsbr
Acute MI and mitral regurg from the murmur leads to LV failure and backflow of blood into the lungs.
This leads to increased pulmonary hydrostatic capillary pressure. This will lead to excess volume leaking from the pulmonary capillaries into the interstitial and this will manifest as pulmonary edema (crackles).
Pulmonary edema will interfere with gas exchange leading to hypoxemia.
pregnancy causes hypervolemia, and higher blood volume/flow through the heart will increase murmurs (aortic regurg.)