Mixed Deck — All CSMLS Topics Flashcards

Northern blotting is used to:

Answer: Detect and quantify specific mRNA transcripts in a sample

Northern blotting separates RNA by electrophoresis, transfers it to a membrane, and hybridizes it with a labeled probe to detect and estimate the size and abundance of specific mRNA molecules.

What type of extinguisher is used for metal fires?

Answer: Class D dry chemical

Explanation: Class D dry chemical extinguishers are specifically designed for metal fires, such as fires involving combustible metals like magnesium, sodium, titanium, or potassium. These extinguishers contain a dry powder agent that effectively smothers and cools the fire, preventing re-ignition and minimizing the risk of explosions.

A titer of 1:320 compared to 1:40 for the same patient indicates:

Answer: Higher antibody concentration in the 1:320 sample

A titer of 1:320 reflects a higher dilution needed to reduce reactivity, indicating a greater concentration of antibody than a titer of 1:40.

The complement pathway initiated by antigen-antibody complexes is the:

Answer: Classical pathway

The classical complement pathway is activated by antigen-antibody (immune) complexes binding to C1q.

A batch of used, non-sharp, blood collection tubes containing clotted human blood must be discarded. According to Canadian Standards Association (CSA) guidelines and general biosafety principles, what is the correct disposal method?

Answer: In a designated, leak-proof biohazard bag/container for autoclaving or incineration.

Human blood and body fluids are considered biohazardous waste. Non-sharp items contaminated with this waste, such as blood tubes, must be placed in designated, labeled, and leak-proof biohazard bags or containers for subsequent decontamination, typically by autoclaving or incineration. [28, 29] Regular garbage is incorrect due to the infectious risk. Sharps containers are specifically for items that can puncture skin, like needles. Disposing of blood down a sink is generally not permitted and is an unsafe practice.

A patient sample for electrolyte analysis is noted to be severely hemolyzed. Which analyte would be most significantly falsely elevated?

Answer: Potassium (K+)

Potassium is the major intracellular cation. Hemolysis, the rupture of red blood cells, releases large amounts of potassium into the serum or plasma, causing a falsely elevated result that does not reflect the patient's true physiological state.

A technologist receives a cerebrospinal fluid (CSF) specimen in the microbiology lab from a suspected case of bacterial meningitis. The specimen is received at 3:00 PM and the Gram stain is performed immediately. The day shift ends at 4:00 PM. Which of the following actions is most critical regarding the culture of this specimen?

Answer: Immediately inoculate the specimen onto appropriate media, such as Chocolate and Blood agar, and place in a CO2 incubator.

CSF is considered a critical, irreplaceable specimen. Potential pathogens that cause meningitis, such as Neisseria meningitidis and Streptococcus pneumoniae, are fastidious and sensitive to temperature changes. The specimen must be processed immediately upon receipt. Delay or improper storage (like refrigeration, which can kill N. meningitidis) can lead to false-negative culture results. Immediate inoculation onto appropriate enriched media (like Chocolate agar) and incubation in a CO2-enriched atmosphere is crucial for the recovery of these delicate organisms.

Which of the following quality system essentials includes processes for selecting and installing laboratory instruments?

Answer: Equipment

Explanation: The quality system essential "equipment" involves processes for selecting, installing, and maintaining laboratory instruments to ensure their proper functioning and accuracy. This includes validation, calibration, and regular maintenance procedures to uphold quality standards in laboratory testing.

According to Canadian Workplace Hazardous Materials Information System (WHMIS) 2015 guidelines, which hazard is represented by the pictogram showing an exclamation mark?

Answer: May cause less serious health effects, such as skin/eye irritation or act as a skin sensitizer

The exclamation mark pictogram under WHMIS/GHS is used for hazards that are less severe than those indicated by the skull and crossbones or health hazard pictograms. It signifies hazards such as being an irritant (skin and eye), a skin sensitizer, causing acute toxicity (harmful), or having narcotic effects. [5, 17] The corrosion pictogram shows damage to materials and skin, the health hazard (exploding person) pictogram indicates serious long-term effects like carcinogenicity, and the flame over circle represents oxidizing hazards. [1]

What is the function of restriction endonucleases in molecular biology?

Answer: To cleave double-stranded DNA at specific palindromic recognition sequences

Restriction endonucleases recognize short specific palindromic sequences and cut both DNA strands at or near those sites, producing defined fragments used in cloning, RFLP analysis, and restriction mapping.

A four-fold rise in antibody titer between acute and convalescent serum samples is considered diagnostic of:

Answer: Active or recent infection with the tested pathogen

A four-fold or greater rise in antibody titer between acute and convalescent samples indicates active infection and seroconversion.

Which of the following scenarios would most likely result in a mixed-field reaction in the forward ABO grouping?

Answer: A Group B patient recently transfused with Group O red blood cells.

A mixed-field reaction shows two distinct cell populations: one agglutinated and one unagglutinated. This is a hallmark of a recent transfusion with a different, compatible ABO group. A Group B patient receiving Group O red cells will have both their own B-antigen-positive cells (which will agglutinate with Anti-B) and the transfused O cells (which will not), creating a mixed-field appearance. [3, 4, 11]

A bone marrow transplant recipient requires a red blood cell transfusion. To prevent Transfusion-Associated Graft-Versus-Host Disease (TA-GVHD), which of the following component modifications is most critical?

Answer: Irradiated

Irradiation is the only method that inactivates donor T-lymphocytes, which are responsible for causing TA-GVHD in severely immunocompromised recipients, such as bone marrow transplant patients. While leukoreduction removes most white cells and CMV-seronegative units prevent cytomegalovirus transmission, they do not reliably prevent TA-GVHD.

The forward type of a patient is Group A, but the reverse type shows an unexpected reaction with A1 cells, suggesting Group O. The patient is a healthy 25-year-old blood donor. What is the most probable cause for this discrepancy?

Answer: The patient is an A2 subgroup with anti-A1.

This discrepancy pattern is characteristic of an A2 individual who has produced an anti-A1 antibody. The patient's red cells are group A (specifically, A2 subgroup) and react with Anti-A. However, their plasma contains the expected anti-B and also an unexpected anti-A1, which reacts with the A1 cells used in the reverse grouping panel. This causes the reverse group to appear like that of a Group O individual. [2, 4, 11]

The presence of Auer rods within blasts on a peripheral blood smear is most strongly associated with which of the following conditions?

Answer: Acute Myeloid Leukemia (AML)

Auer rods are needle-like, azurophilic cytoplasmic inclusions that are pathognomonic for myeloid blasts. They are formed from the abnormal fusion of primary granules. While not present in all cases of Acute Myeloid Leukemia (AML), their presence confirms a myeloid lineage and is a key morphological feature for diagnosing AML, particularly the acute promyelocytic leukemia (APL) subtype.

Normal CSF total protein is approximately:

Answer: 0.15–0.45 g/L

Normal CSF total protein ranges from 0.15 to 0.45 g/L, which is much lower than plasma protein levels due to the blood-brain barrier.

Which of the following factors is a possible cause for cocci in chains to appear pink on a gram stain?

Answer: The patient is on antibiotics

Explanation: Antibiotic use can affect the cell wall of bacteria, leading to altered staining characteristics. In the case of cocci in chains appearing pink on a Gram stain, it suggests that the bacteria may have lost their ability to retain the crystal violet dye due to antibiotic-induced changes in cell wall structure.

A tech runs a quality control for creatinine and the result is 2 standard deviations above the mean. According to Westgard rules, what is the most appropriate first step?

Answer: Repeat the control on the same vial.

A single control value exceeding 2 standard deviations (a 1-2s rule violation) serves as a warning. The most common cause is random error. The initial step is to repeat the measurement using the same vial of control material to see if the error was random and self-corrects. If it remains out, further investigation is needed.

Oval fat bodies seen in urine microscopy are associated with:

Answer: Nephrotic syndrome

Oval fat bodies are renal tubular cells or macrophages containing absorbed lipids and are characteristic of nephrotic syndrome.

Which of the following actions should be taken when tissue sections stained with hematoxylin and eosin show pale cytoplasmic staining?

Answer: Check the pH of eosin and adjust with acetic acid if necessary

Explanation: Eosin is an acidic dye, and its pH affects the staining quality. If tissue sections show pale cytoplasmic staining, it indicates potential issues with eosin staining. Checking the pH of eosin and adjusting it with acetic acid if necessary can help restore optimal staining conditions, leading to improved cytoplasmic staining in histological specimens.