Media Lab
Within what period of time after performance of the tuberculin skin test (TST) should the result be read?
48-72 hours The skin test for exposure to tuberculosis (TB) is an example of a type IV hypersensitivity reaction (delayed hypersensitivity reaction). A small amount of antigen is injected under the skin. The result is read 48 - 72 hours after the intradermal injection to look for the presence of a lesion greater than or equal to 10 mm in diameter. This result would indicate the possibility that the individual was exposed to Mycobacterium tuberculosis. Individuals who have strongly positive reactions, a skin test diameter greater than 15 mm, and symptoms suggestive of TB should be evaluated clinically and microbiologically. Two sputum specimens collected on successive days should be investigated for TB by microscopy and culture.
A medical laboratory scientist is working with a student on the teaching microscope. The student is using a microscope that has a micrometer for measurement of microscopic items. A normal red cell distribution curve for a patient is shown on the right. What should the range of red cell diameters be when the student measures the red cells with a micrometer?
6-8 microns Red blood cells that are a homogenous population of cells, 6-8 µm in diameter, will have a normal Gaussian distribution curve as shown on the right. If the red cells were 2-4 or 4-6 microns in diameter the distribution curve would be shifted to the left of normal. Red blood cells that are >8 microns will have a peak that is further to the right than the normal peak.
A rosette test to screen for fetomaternal hemorrhage (FMH) is indicated in all of the following situations, EXCEPT:
A D-positive mother The correct answer is a D-positive mother. The mother should be D-negative and the infant should be D-positive or weak-D positive.
Two CSF specimens were sent to the Lab with the following results:Tube #1 = 11,200 rbc/µLTube #2 = 300 rbc/µLThe results on these CSF specimens are indicative of:
A traumatic tap Traumatic taps are described as spinal fluid taps where blood vessels are pierced with the needle during aspiration, causing a contamination of the spinal fluid sample with blood or bone marrow. Traumatic taps are easily differentiated from true hemmorhages as each subsequent container of spinal fluid drawn will have a smaller amount of red and white cells present. In a true hemorrhage, the red and white cell counts will remain steady in each subsequent tube of spinal fluid drawn.
Which of the following is the cause of thrombotic thrombocytopenic purpura (TTP)?
ADAMTS13 deficiency Thrombotic thrombocytopenic purpura (TTP) is caused by a deficiency of the enzyme ADAMTS13. ADAMTS13 is responsible for breaking up microthrombi made up of platelets and von Willebrand factor. Because of the deficiency, these microthrombi remain on the subendothelium, creating the environment that causes the findings of TTP.A deficiency of TPO is not the cause of TTP.Antibodies are known to cause immune thrombocytopenia (ITP) but not TTP.The term idiopathic implies that the cause is not known. The cause of TTP is now known to be a deficiency of ADAMTS13.
In an standard electrophoretic separation, what zone appears first (anodal end) on the densitometric pattern?
Albumin Using standard serum protein electrophoresis methods, serum proteins separate into five bands in the following order: albumin travels farthest toward the anode followed by a1-globulins, a2-globulins, ß-globulins, and gamma-globulins.
Illustrated in the top image is a 3.5-day-old brown/black, smooth yeast colony that is usually considered a contaminant when recovered in laboratory cultures. Reports of verrucose skin and visceral infections with this black yeast have been reported. The bottom image illustrates the microscopic view as prepared in a mount prepared from the surface of the colony. Note the background dark-staining hyphae from which are produced small, elliptical conidia. Select from the choices below the correct presumptive identification of this isolate.
Aureobasidium pullulans Aureobasidium pullulans is the correct response. The relatively rapidly-growing, brown pigmented colony is not species specific. The identification can be made by the microscopic view of a touch preparation from the surface of the colony in which dark dematiaceous hyphae are observed in the background. Myriads of elliptical, single cell conidia are also present, being produced from the hyphae. Although most commonly a contaminant when recovered in laboratory cultures, reports of infections have been published (Bolignano, G., and Crisco G. J. Clin Microbiol 41: 4483, 2003).Exophiala jeanselmei colonies are often yeast-like upon initial isolation, later becoming a velvety yellow brown to black mold on maturity. In microscopic mounts, darkly pigmented hyphae are also observed, from which loose clusters of dark-staining elliptical conidia are produced from distinctive long narrow conidiophores with a sharply pointed tip.Phaeoannellomyces werneckii is another of the "black yeasts", distinguished by the microscopic production of elongated yeast cells that are divided into segments when a daughter cell is produced from an extension from the mother cell that then contracts to form a scar (annelide).Cladophialophora carrionii colonies are more in the form of a slow growing smooth mold distinguished by distinctive cladosporium type sporulation in which long, un-branched chains of elliptical conidia are produced, with each pair separated by a scar-like dysjunctor.
In post-hepatic jaundice, why is urobilinogen decreased?
Because there is a blockage of conjugated bilirubin being excreted from the liver to intestine By definition, post-hepatic jaundice is blockage or issue with liver excretions into the bile ducts and intestines (hence post: after the liver). Due to the decrease excretion of products from the liver, there will be less conjugated bilirubin being excreted which will lead to a decrease in the formation of urobilinogen. Urobilinogen is created from conjugated bilirubin in the intestines from the work of bacteria. If there was an issue with the liver's ability to conjugate or metabolize, we would see hepatic jaundice not post-hepatic. A decrease or increase bilirubin metabolism, or an increase in hemolysis, there would be either pre-hepatic or hepatic jaundice.
Which is in the correct order from the lowest concentration of H antigen to the highest concentration of H antigen?
Bombay, A1B, A1, A2B, B, A2, O The H antigen is an essential precursor to the ABO blood group antigens. Individuals with the rare Bombay phenotype (hh) do not express antigen H on their red blood cells; therefore, this type would contain the least amount of H antigen. Those which are type A1B would then have the second to least amount of H antigen since the precursor H antigens have been formed into A1 and B antigens instead. The remaining order of the H concentration from lowest to highest in the blood types given is: A1, A2B, B, A2, and O. O patients produce the most H antigen since they do not convert the H antigen into A or B antigens on their cell surface.
This form, which measures 30 µm by 15 µm was found in stool. What is the identification?
Clonorchis sinensis egg Clonorchis sinensis eggs are characterized by an operculum on one end of the egg, and a small knob on the other end of the egg. Also, there is a distinct rim around the operculum, which is referred to as shoulders. The size of the eggs is approximately 30 µm by 15 µm. Diphyllobthrium latum eggs also have an operculum and terminal knob, but no shoulders. The egg is also much larger with an average size of 65 µm by 48 µm. Paragonimus westermani eggs also have an operculum and shoulders, but do not have a terminal knob. They do show a terminal shell thickening. The eggs are also much larger, ranging from 78-120 µm by 45-60 µm. Fasciola hepatica eggs also have an operculum, but they do not have a terminal knob or shoulders. The eggs are also much larger, about 128-150 µm by 60-90 µm.
The measurement of sodium and chloride in sweat is the most useful test for the diagnosis of what condition/disease?
Cystic fibrosis Measurement of the sodium and chloride concentration in sweat is the most useful test in the diagnosis of cystic fibrosis. Significantly elevated concentrations of both ions occur in more than 99% of affected patients.The definitive test for steatorrhea (failure to digest or absorb fats) is the quantitative fecal fat analysis.The secretin/CCK (cholecystokinin) test is the direct determination of the exocrine secretory capacity of the pancreas.Pancreatic cell tumors, which overproduce gastrin, are called gastrinomas; they cause Zollinger-Ellison syndrome and can be duodenal in origin.
All of the following are indicators of sepsis, EXCEPT? Erythrocytosis Increased heart rate Leukocytosis Increased body temperature
Erythrocytosis Sepsis results in an immune response by the body. This response includes increasing body temperature and leukocytes in order to help fight off the infection, and increased heart rate in order to get more blood and oxygen to the tissues. Erythrocytosis is not part of the immune response.
Which of the following will give the best overall picture of a patient's iron stores:
Ferritin Ferritin is one of the main forms in which iron is stored in the body, the other form is hemosiderin. The concentration of circulating ferritin is proportional to the size of iron stores. Albumin is a nonglycosylated protein synthesized in the liver whose function is to transport a large number of compunds such as free fatty acids, bilirubin, calcium, hormones, drugs, etc. Transferrin is a beta globulin which is involved in iron transport throughout the body. Haptoglobin is a glycoprotein which binds free hemoglobin and prevents it from being cleared by the renal system and subsequently preventing iron loss.
Which of the following methods for long-term diabetic monitoring is recommended for patients with sickle cell anemia?
Fructosamine In sickle cell anemia, rapid hemoglobin turnover may be present. HbA1c and other glycosylated hemoglobin assays are not valid in rapid hemoglobin turnover and hemoglobinopathy conditions. Fructosamine measurements are more sensitive than HbA1c in monitoring long term diabetes in patients with such conditions. Fructosamine (also called glycosylated albumin) is formed by the nonenzymatic attachment of glucose to amino groups of proteins other than hemoglobin. Because albumin is the most abundant serum protein whose halflife is about 20 days, the concentration of glycosylated albumin reflects the consumption of glucose over a period of 2-3 weeks. This feature makes fructosamine the test of choice for monitoring diabetic control in patients with hemolytic anemias such as sickle cell anemia, thalassemia, and autoimmune hemolysis.
A pediatric patient arrived at the doctor complaining of itching eyes that appeared red and slightly purulent. When a sample was submitted to the laboratory, the sample grew only on the chocolate plate as seen in the upper image. When performing a satellite test, the image on the bottom is observed. What is the most likely identity of the organism causing this patient's symptoms?
Haemophilus influenzae Haemophilus influenzae will grow on the chocolate plate as observed in the upper image. It will also exhibit growth on the satellite test as observed in the lower image. In pediatric patients, it is the leading cause of conjunctivitis, which is the condition described in the question above. Moraxella catarrhalis and Streptococcus pneumoniae would grow on sheep blood agar in addition to the chocolate agar, thus it would not be necessary to perform a satellite test, as the organisms would not grow in a satellite formation. Both organisms are common causes of conjunctivitis, but would not grow as described above. Listeria monocytogenes would grow on sheep blood agar and chocolate agar at standard incubation temperature (35-37°C), but grows optimally at 30-35°C. Since it grows well on both sheep blood agar and chocolate agar, it would be unnecessary to perform the satellite test.
When operating a centrifuge, what happens if the centrifugation time is reduced and the speed increased?
Hemolysis of red cells can occur. Reduced centrifugation time and increased speed can cause hemolysis which can interfere with accurate testing. Improper balance of the centrifuge can result in potential tube breakage, exposure to biohazardous agents, and mechanical centrifuge damage. Compliance with standard procedures will avoid these effects.
Which occurrence is a medical error?
Incompatible blood is transfused into a patient during surgery A medical error is a preventable adverse effect of care whether intended or not and whether it caused harm to the patient or not. Transfusing of incompatible blood is a medical error because it is a mistake that can cause unintended injury to the recipient. If a technologist drops and breaks a bottle of chemistry reagent this may cause physical damage to the laboratory surfaces, but it would not be a medical error. The reagent may even splash the employee, but it would not be considered a medical error because the technologist was not providing care when he or she dropped the reagent. Testing and diagnosing a patient with acute leukemia would not be medical error unless the diagnosis was later determined to be incorrect. Analyzer malfunctions and test results being rejected as invalid would not be a medical error unless patient results were released from the instrument during the period of malfunctions and not communicated and corrected.
How should the organisms that are indicated by the arrows be reported?
Intracellular gram-negative diplococci The most complete report is "Intracellular gram-negative diplococci." It is important to state that the organisms are located intracellularly. If this sample were collected from a male with urethritis, the appearance of gram-negative diplococci inside polymorphonuclear leukocytes is diagnostic. Stating just gram-negative, gram negative cocci, or intracellular gram-negative cocci does not give a complete and accurate depiction of the Gram stain and could be misleading in some clinical scenarios.
A 27-year-old male submitted a stool for culture and parasite study. The culture revealed no enteric pathogens. The suspicious form in the photograph was seen on the permanent trichrome stain. It measured 10 µm. Which of the following is the most likely identification?
Iodamoeba butschlii Iodamoeba butschlii cyst is oval with a single often irregularly shaped karyosome. It contains a large well defined glycogen vacuole. The vacuole appears as an empty space on trichrome stains. The cyst size is 6 to 15 µm. The vacuole and single nucleus are key defining characteristics in this case. Endolimax nana cyst is oval with a large, irregularly shaped karyosome. The nucleus contains four nuclei.Entamoeba coli mature cyst contains eight nuclei. An immature cyst may contain one to eight nuclei. Each nuclei contains a large eccentric karyosome with uneven peripheral chromatin. The cyst in the photograph contains one nucleus and no peripheral chromatin.Acanthamoeba species is a tissue parasite and is not found in stool. It is found in CSF samples and brain biopsies.
Which one of the following statements about urea is false?
It is decreased in dehydration Urea is actually increased, not decreased, during bouts of dehydration. Urea accounts for 75% of nonprotein nitrogen excreted by an individual, it is elevated in a variety of glomerular, tubular, interstitial, and vascular renal diseases, and the reference range for normal individuals is 7 to 18 mg/dL when expressed as blood urea nitrogen.
Serum calcitonin is typically elevated in which of the following conditions?
Medullary carcinoma of the thyroid Serum calcitonin is normally produced by the C cells of the thyroid. It functions to reduce serum calcium by inhibiting release of calcium from bone. It is a peptide with a molecular weight of 3400, and has a half life of approximately 12 minutes. It is characteristically elevated in medullary carcinoma of the thyroid. Since medullary carcinoma often occurs as an autosomal disorder, family members of patients with this condition should be screened for serum calcitonin. It is not associated with hyperthyroidism, glioblastoma, or adrenal adenoma.
An 18-year-old female has a CBC performed as part of a routine physical exam. The following results were obtained and the physician determines she is anemic. After reviewing her CBC results shown below, which of the following would be an appropriate description of the anemia? White blood cells (WBC) 5.6 x 109/L 4.0-10.0 x 109/L Red blood cells (RBC) 3.7 x 1012/L 4.2-5.9 x 1012/L Hemoglobin 9.9 g/dL 12-16 g/dL Hematocrit 28%37-48%MCV75 fL 80-100 fL RDW-CV 14% 11.0-15.0%
Microcytic, homogenous cell population The MCV is indicative of microcytosis with MCV=<80fL. The RDW is within normal limits and indicative of a homogenous cell population. If the MCV were >100 fL, this would be indicative of macrocytosis. An RDW that was above reference range would be indicative of a heterogenous cell population.
Which of the following conditions is most likely when an oligoclonal band is seen in CSF electrophoresis without a corresponding serum peak?
Multiple sclerosis Oligoclonal bands are found in the gamma region of CSF electrophoresis of most patients with multiple sclerosis. These bands are not seen in the serum electrophoresis of the same patients and are caused by increased levels of IgG in the CSF. Other conditions that may show oligoclonal bands in CSF electrophoresis include, inflammatory conditions, Guillain-Barre syndrome, bacterial meningitis, viral encephalitis, neurosyphilis, and subacute sclerosing panencephalitis.
To screen for urinary tract infections, leukocyte esterase results should be evaluated along with the results from which of these other reagent strip tests?
Nitrite To screen for urinary tract infections leukocyte esterase should be coupled with nitrite. Urinary nitrites can help to detect the presence of gram-negative bacterial organisms that are the typical cause of urinary tract infections.
A pregnant female has been injected with Rh Immune Globulin (RhIG) antenatally (28 weeks gestation) and has a positive antibody screen at delivery. The antibody has been confirmed as anti-D alone and reacts only weakly (1+ in the indirect antiglobulin test). This antibody may be the result of:
Passive anti-D (RhIg) received at 28 weeks. Rh Immune Globulin is administered at 28 weeks of gestation and at delivery to help prevent pregnant women from becoming actively immunized to the D antigen. RhIG is given because during pregnancy and at delivery fetal blood can enter maternal circulation. This exposure to the D antigen puts the mother at risk for becoming sensitized and making an anti-D. Women who are Rh negative carrying an Rh positive fetus now receive RhIG at 28 weeks (antenatal) and at delivery (within 72 hours of delivery) to clear fetal red blood cells from maternal circulation. The RhIG can attach to fetal red blood cells which are then cleared by macrophages. At delivery some Rh negative women have a weakly reactive anti-D still in circulation from RhIG administration at 28 weeks of gestation (antenatal). The anti-D has been demonstrated to stay in circulation 2 months or even longer in some cases. Massive fetomaternal hemorrhage may sensitize a woman but this would not be detected at delivery. Wharton's jelly would be present in the cord sample from the baby and may cause incorrect results (rouleaux) for the baby. The mother is Rh negative since she received RhIG so the anti-D present is not an autoantibody.
Which of the following conditions would be suggested by a jaundiced patient experiencing a marked rise in alkaline phosphatase (ALP), conjugated bilirubin, and a slight rise in alanine aminotransferase (ALT)?
Post-hepatic cholestasis Post-hepatic cholestasis (stoppage or suppression of the flow of bile) is characterized by jaundice, a marked increase in ALP, GGT, conjugated bilirubin, as well as other hepatic enzymes. The slight rise of ALT suggests that the issue is not hepatitis. Renal and cardiovascular failure do not match the symptom of jaundice or the abnormal laboratory values.
What would be the next step when an EDTA specimen had an automated platelet count of 61,000/mm3 and the platelets were surrounding the neutrophils on the differential?
Recollect a specimen for a platelet count without using EDTA Occasionally platelet satellitism can occur in some patient samples when collected in EDTA. The solution for this problem is to recollect in a different type of anticoagulated tube, usually a sodium citrate tube to prevent the platelets from adhering to the neutrophils. The platelet count would be multiplied by 1.11 to account for the dilution of the blood sample with sodium citrate (9:1).
A 62-year-old female undergoing chemotherapy for breast cancer developed fever, abdominal pain, and foul-smelling diarrhea after receiving clindamycin for 5 days. The photomicrograph is an H & E-stained section of colon biopsy revealing focal ulceration and pseudomembranous inflammation. Each of the following laboratory findings will confirm the presumptive diagnosis of Clostridium difficile-associated colitis EXCEPT:
Recovery of C. difficile in the stool The recovery of C. difficile in stool specimens by itself is insufficient to establish a diagnosis of C. difficile-associated colitis. Rather, it is also necessary to demonstrate that the strain recovered is toxin-producing. The other tests/results listed in this question confirm the diagnosis of C. difficile disease when pseudomembranous colitis is demonstrated on the biopsy. All tests have some chance for either false positive or false negative results and careful clinical and histopathological correlation is needed before a causal relationship can be demonstrated.
What is the purpose of the BNP test?
Rules out acute heart failure in the emergency setting. B-type natriuretic peptide (BNP) is a cardiac hormone released by the heart during stressful situations such as ventricular volume expansion and pressure overload. The main clinical utility of BNP is that a normal level rules out acute heart failure in the emergency setting. Blood urea nitrogen (BUN) is the test used to determine the amount of urea in the blood. Prothrombin time (PT) is the test used to evaluate abnormalities in the extrinsic coagulation pathway and monitor coumarin therapy. Activated partial thromboplastin time (aPTT or PTT) is the test used to Evaluate abnormalities in the intrinsic coagulation pathway and monitor heparin therapy.
The cell diameter of a normal RBC is slightly smaller than the nucleus of which of the following blood cells?
Small lymphocyte Normal red blood cells are round, biconcave, and measure about 6-8 µm in diameter. Their size can be compared to the nucleus of a small lymphocyte. This is a good way to estimate RBC shape on a peripheral smear if the MCV is not available. Monocytes are typically 12-18 µm in diameter with a nuclear:cytoplasmic ratio of 2:1, which would make the nucleus larger than a normal RBC. Band Neutrophils are typically 10-16 µm in diameter with an elongated, curved nucleus, which is also larger than a normal RBC. Plasma cells are fully differentiated B lymphocytes and measure between 8-20 µm in diameter. These cells are larger than small lymphocytes and the nucleus would also be larger than a normal RBC.
The image is a stained smear of cerebrospinal fluid. Which of the following statements is true about the cells shown at the right?
They line the arachnoid space. The cells seen here are ependymal cells which are found in the tissues lining the ventricles, the neural canal, and the arachnoid space. Notice the less distinct cell borders and the nucleoli.
What abnormaility is present in the white blood cell indicated by the arrow?
Toxic granulation The cell is exhibiting toxic granulation. Toxic granulation is found in neutrophils and can be seen in certain infections and inflammations. Dohle bodies are light blue-gray bodies and are composed of aggregates of rough endoplasmic reticulum. They are associated with severe bacterial infections and are often seen with toxic granulation (although not in this image). Pelger-Huet anomaly is a benign neutrophilic disorder characterized by hyposegmented nuclei. Auer rods are fused primary granules and are therefore only seen in cells that would contain primary granules, such as myeloblasts and promyelocytes.
Regarding therapeutic drug monitoring, which of the following statements is correct when collecting a specimen for a trough level?
Trough level is tested on a blood sample that is collected immediately prior to when the next dose of the drug is given. The lowest level of the drug in the patient's body is called the trough level. The peak for a drug is when the level of the drug in the patient's body is the highest. To assess drug concentrations during the trough phase, blood should be drawn immediately before the next dose. To assess peak levels, the time for drawing depends on the route of administration: Intravenous (IV): 15 - 30 minutes after injection/infusion Intramuscular (IM): 30 minutes - one hour after injection Oral: One hour after drug is taken (assumes a half-life of > two hours)
The most significant class of microbial targets for Natural Killer (NK) cells is:
Viruses Natural Killer (NK) cells are essential mediators of virus immunity. A deficiency of NK cells in human beings leads to uncontrolled viral replication and a poor clinical outcome. NK cells have a major role in controlling pathogens, especially viruses. Human patients with selective NK-cell deficiencies have recurrent, severe viral infections. NK cells destroy target cells through an extracellular non-phagocytic mechanism referred to as a cytotoxic reaction. NK cells will actively kill virally infected target cells, and, if this activity is completed before the virus has time to replicate, a viral infection may be stopped. NK cells are highly responsive to IL-2, IL-7, and IL-12. These cytokines generate high cytokine-activated killer activity in these cells. The immune defense against bacteria is phagocytosis which is a function of polymorphonuclear neutrophils (PMNs), monocytes, and macrophages. Host defense against extracellular bacteria is also offered by the CD4+ subset, TH17. Eosinophils may play a role in the host defense mechanism because of the ability to kill certain types of parasites. An eosinophil can interact with the larval stages of some helminth parasites and damage them through oxidative mechanisms. Certain proteins released from eosinophilic granules damage antibody-coated Schistosoma parasites. In addition, subsets of CD4+ (TH1 and TH2) lymphocytes function in host defense against certain parasites. The TH2 lymphocyte subset mediates host defense against extracellular parasites, including helminths. Host defense against fungi and extracellular bacteria is is offered by the CD4+ subset, TH17.
Which of the following is TRUE of a fully compensated metabolic acidosis?
pH will be normal with a decrease in pCO2 The pH will be normal in a fully compensated form of any alkalosis or acidosis. In this case, the problem is metabolic, meaning there is a decrease in bicarbonate (alkaline) production which has reduced the pH of the blood. To compensate for this, the patient hyperventilates thus reducing the amount of acid, or pCO2 in the system to balance the pH into normal range.
The normal range for urine pH is:
4.5 to 8.0 Normal urine pH varies from 4.5 to 8.0. After meals, urine becomes more alkaline due to gastric acid secretion (alkaline tide). At night due to shallow breathing, it becomes more acid. A high meat diet results in a more acid urine than a vegetarian diet, due to excretion of phosphates and sulfates. The kidneys maintain normal acid-base balance primarily through the reabsorption of sodium and the tubular secretion of hydrogen and ammonium ions. Urine becomes increasingly acidic as the amount of sodium and excess acid retained by the body increases. Alkaline urine, usually containing bicarbonate-carbonic acid buffer, is normally excreted when there is an excess of base or alkali in the body. Secretion of an acid or alkaline urine by the kidneys is one of the most important mechanisms the body uses to maintain a constant body pH.
The primary antibody response takes an average of how many days?
5-10 days The primary immune response takes approximately one week, or 5-10 days, to occur. The secondary immune response typically has a shorter lag period, which is approximately 1-3 days. The primary immune response typically does not begin as early as 3-4 days. A lag time of 14-21 days is exceptionally long and would lead to additional issues with the infection.
How long does it take for plasma concentrations to reach steady state when a patient's dose is given at intervals of the drug's half-life?
5-7 half-lives As repeated doses of a drug are given to a patient, the drug's plasma concentration accumulates and reaches a steady state. This is when the amount of drug in the plasma has built up to a concentration level that is therapeutically effective and as long as regular doses are administered to balance the amount of drug being cleared the drug will continue to be active. The time taken to reach the steady state is about five-seven times the half life of a drug.
The characteristics of an acute phase protein include the following EXCEPT:
Acute phase proteins are synthesized slowly in response to tissue injury. 'Acute phase proteins are synthesized slowly in response to tissue injury' is the correct answer. The majority of acute phase proteins are synthesized rapidly in response to tissue injury, e.g. inflammation, infection, malignant neoplasia, trauma, surgical procedures, or drug responses. Acute phase proteins have different kinetics and various degrees of increase. The elevation is twofold to five-fold in certain disease states. A group of glycoproteins associated with the acute-phase response are collectively called acute-phase proteins of acute phase reactants. More than 20 acute-phase proteins have a definable role in inflammation. An acute phase response is a non-specific indicator of an inflammatory response. C-reactive protein (CRP) is an acute phase protein. CRP is prominent among the acute-phase proteins because its changes show great sensitivity. Changes in CRP are independent of other laboratory tests, such as the erythrocyte sedimentation rate, and parallel the inflammatory process. CRP returns to lower undetectable levels as an inflammation subsides. Laboratory measurement of an acute phase can be used to monitor the progress of therapy in inflammatory diseases. The acute phase protein, CRP, is used clinically for monitoring infection, autoimmune disorders, and more recently, healing after a myocardial infarction.
Which of the following processes can lead to the formation of microclots in a patient specimen that is collected in a tube containing EDTA anticoagulant?
Failing to invert the tube after specimen collection. Failing to invert a tube, delayed inversions, or inadequate inversions of a tube containing an anticoagulant such as EDTA can cause the formation of microclots. This can result in a falsely-decreased platelet count. The other choices that are listed are all acceptable practices and will not cause the formation of microclots in an EDTA tube.
A spinal fluid was sent to the laboratory for testing. When the hematology tech performed the cell differential, she noticed encapsulated yeast as seen in the images to the right. Upon further investigation, she determined that the patient was immunocompromised and had a recent history of pneumonia. Which of the following would be the most beneficial test to determine a diagnosis?
Cryptococcus neoformans antigen test Cryptococcus neoformans antigen test is the correct answer because this antigen test has a high sensitivity and specificity for Cryptococcus neoformans detection. Cryptococcus neoformans is an encapsulated yeast that can be seen in immunocompromised patients due to its opportunistic capability. CSF Gram Stain is incorrect because this test has a lower sensitivity and specificity when compared to the cryptococcal antigen test. Any time a spinal fluid is sent for culture, a gram stain is performed, but if the organism causing the infection is in low numbers, the organism can be missed on the gram stain. Fungal Culture is incorrect because this test may take several days to detect growth of Cryptococcus neoformans. For a more rapid result, the cryptococcal antigen test can be performed within minutes and treatment started sooner for a quicker recover. Patients suspected of having a Cryptococcus neoformans meningitis typically will have a CSF fungal culture performed, in addition, to the cryptococcal antigen test. India Ink is incorrect because this test has a lower specificity and sensitivity when compared to the cryptococcal antigen test. Some strains of Cryptococcus neoformans may not be encapsulated resulting in a false-negative India ink stain.
What is the identification of this cellular clump found in CSF? Note the presence of many similar-appearing nuclei without distinct lines of demarcation between cells.
Ependymal clump A key feature in identifying ependymal clumps is the presence of many similar-appearing nuclei without distinct lines of demarcation between cells. Basically, this cellular clump appears as one large cell, instead of many individual cells. On the other hand, choroid plexus clumps, mesothelial clumps, and macrophages do not display this "fused" morphology between cells. These types of cell clumps appear as individual cells gathered into a grouping. Cartilage cells usually occur singly. They are medium to large sized cells with cytoplasm that stain wine red (with deep wine red nucleus). Tumor cells often occur in clumps. Cells in the clump are dissimilar, and some are multinucleated with variation in nuclear size. There are usually no clear spaces between the cells. Lymphoblasts can occur in CSF in acute lymphoblastic leukemia (ALL). They have the characteristics of lymphoblasts seen in blood with basophilic cytoplasm.
All of the following colony and microscopic descriptions are paired correctly with the mold indicated, EXCEPT: Macroscopic description: rose red or purple red pigmentation Microscopic description: multi-celled, sickle shaped macroconidia Fusarium sp. Macroscopic description: grayish-brown colonies Microscopic description: Dark, elliptical conidia each supported by a conidiophore ("lollipops") Scedosporium apiospermum Macroscopic description: green, granular, rugose colonies Microscopic description: chains of spherical conidia produced from branching phialides Aspergillus sp. Macroscopic description: green lawn that extends from edge to edge Microscopic description: tight clusters of spherical conidia held by finger-like phialides Gliocladium sp.
Macroscopic description: green, granular, rugose colonies Microscopic description: chains of spherical conidia produced from branching phialides Aspergillus sp. The correct answer is macroscopic description: green, granular, rugose colonies; microscopic description: chains of spherical conidia produced from branching phialides; Aspergillus sp. "Chains of spherical conidia produced from branching phialides" is descriptive of Penicillium species, which typically produces green, granular, rugose colonies. "Multi-celled, sickle shaped macroconidia" is the description for Fusarium species, which produces colonies with a distinctive rose red or purple red pigmentation. "Dark, elliptical conidia each supported by a conidiophore ('lollipops')" is characteristic of Scedosporium apiospermum. The grayish-brown appearance is typical macroscopic morphology. The description of "tight clusters of spherical conidia held by finger-like phialides" is the microscopic description for Gliocladium, the colony of which typically appears as a "green lawn" that extends from border to border across the Petri dish.
What characteristic is common to all of these conditions: hereditary spherocytosis, hereditary elliptocytosis, hereditary stomatocytosis, and paroxysmal nocturnal hemoglobinuria?
Red cell membrane defects Red cell membrane defects are present in each of the choices above, resulting in abnormal morphology and some degree of hemolysis. Only 75% of hereditary spherocytosis shows an autosomal dominant pattern. Hereditary elliptocytosis is autosomal dominant. Paroxysmal nocturnal hemoglobulinuria is an acquired clonal stem cell mutation that makes red cells more susceptible to lysis. Hereditary stomatocytosis is usually autosomal dominant, but the presence of stomatocytes may be related to Rh deficiency syndrome (or artifact). No autoimmune mechanism is associated with these conditions, so the direct antiglobulin test is not expected to be positive. HbC is found in beta-globin gene mutation that causes HbC disease. None of these conditions produce HbC.
Which of the following is an important technique consideration in order to obtain consistently high quality bone marrow smears?
Select or concentrate bone marrow spicules, ensuring they are transferred to the slide. In order to obtain consistently high quality smears, it is necessary to select or concentrate the bone marrow spicules (fragments). Selecting or concentrating fragments can be performed with different methodologies. At the patient bedside, some clinicians will use the touch-preparation or pull-preparation method, while tilting the slide to allow excess blood to roll off. This leaves more of the bone marrow spicules on the slide. This can be wasteful and rather messy but does not require a high level of skill.A less wasteful method is to pour a portion of the marrow aspirate into a small petri dish and swirl it about, then tilt the dish to reveal the marrow spicules. These can then be extracted using a capillary pipette with a micro-pipette bulb and transferred to the slide for use in making smears. This technique allows the laboratory professional to make numerous smears containing fragments rather than relying on the random luck of the drop. You would not want to use a very large drop of marrow as this would probably not smear out to a readable layer of cells. Slides can be prepared at the patient bedside if the work area is prepared sufficiently to ensure slides can be easily made. Making slides at the patient bedside is also dependent on hospital policy. It is important to prepare as many slides as possible from the obtained sample to provide the opportunity for choosing the best quality slides and for special stains, if needed.
A 6-year-old girl was seen in the emergency department with pain and tenderness in her lower right quadrant. A CBC showed a high white blood cell count with increased segmented neutrophils and bands. The child was admitted to surgery with a diagnosis of appendicitis. During surgery the appendix appeared normal, but an enlarged node was removed and cultured. A diagnosis of mesenteric lymphadenitis was made. Gram-negative rods were isolated. Which of the following biochemical results are most likely produced by the suspect organism?
TSIA acid over acid, H2S negative, lysine negative, indole variable, urea positive The correct answer is TSIA acid over acid, H2S negative, lysine negative, indole variable, urea positive. This case is typical of Yersinia enterocolitica and the biochemical reactions listed are consistent for this organism. Y. enterocolitica generally presents as severe lower abdominal pain mimicking appendicitis, but infects the mesenteric lymph nodes and may infect the appendix and ileum. TSIA acid over acid, H2S negative, lysine positive, indole positive, urea negative is typical of Escherichia coli. TSIA alkaline over acid, H2S positive, lysine negative, indole negative, urea variable, as well as TSIA acid over acid, H2S positive, lysine positive, indole variable, urea negative are both H2S positive, which is not descriptive of Y. enterocolitica.
Molecular methods offer improvements in sensitivity, but they are dependent upon what factor?
The availability of specific instrumentation Molecular methods do require appropriate instrumentation for implementation and detection. However, molecular assays can have some draw-backs such as expense, the need of specially trained personnel, decontaminated space, and specific analyzers for detection. Molecular methods do not depend on having large numbers of organisms in a clinical sample. Some molecular methods, such as Polymerase Chain Reaction (PCR), can amplify a single copy of target DNA so into large amounts of the target for detection. Some methods can detect such low levels of an organism, even if that organism is not the cause of infection. Under the ideal circumstances and conditions, culture methods can provide a sensitive means of detecting an organism. However, some organisms are highly fastidious and require specific media and incubation conditions for optimum recovery; these may not be available in every laboratory. Culture also requires the presence of viable organisms, and may not be able to recover organisms present in very low numbers. Molecular methods do not require a living organism because it detects target DNA or RNA sequences.
A defect in which of the following factors causes impaired platelet adhesion and aggregation?
Von Willebrand factor In hemostasis, the adhesion of platelets to the collagen exposed on subendothelial cell surfaces is mediated by von Willebrand factor (vWF). vWF acts as a bridge between a specific glycoprotein complex on the surface of platelets and collagen on the subendothelial surface. Stuart-Prower factor, more commonly called factor X, is a member of the vitamin K dependent prothrombin group of factors. Factor X and factor Va form the prothrombinase complex which is responsible for cleaving prothrombin into thrombin. Factor X is not directly involved in platelet adhesion and aggregation. Hageman factor, also known as factor XII, is a contact factor in the intrinsic pathway. It is responsible for activating Fletcher factor. A deficiency in Hageman factor is rarely clinically significant. Hageman factor is not directly involved in platelet adhesion and aggregation. Fletcher factor, also known as prekallikrein or pre-K, is a contact factor in the intrinsic pathway. When Fletcher factor is activated by factor XIIa (Hageman factor) it becomes kallikrein. The contact factor complex of HMWK:Fletcher factor:XII is responsible for activating factor XI. A deficiency in Fletcher factor is rarely clinically significant. Fletcher factor is not directly involved in platelet adhesion and aggregation.
