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The test for glucose is a double sequential enzyme reaction, utilizing the glucose-oxidase/peroxidase method. In the first reaction, glucose oxidase catalyzes the oxidation of glucose to gluconic acid and hydrogen peroxide. Then, the peroxidase catalyzes the oxidation of a chromogen by the hydrogen peroxide to form a colored product. This method does not react with lactose, fructose or galactose. Study the dipstick color chart to become familiar with the range of color changes. The urine specimen should be at room temperature for these enzyme reactions to occur properly.

There are two basic types of tests that are used to screen or monitor glycosuria -- copper reduction tests and enzyme tests. Most enzyme tests use the enzyme glucose oxidase impregnated on a dipstick along with a chromagen, and are specific for detecting only glucose. The copper reduction tests, however, detect any reducing substance. Clinitest® uses the classic Benedict’s copper reduction reaction. Any reducing substances present in the urine will react with the copper sulfate reagent, and the blue cupric sulfate is subsequently reduced to cuprous oxide. The resultant color change from blue through green to orange is proportional to the amount of reducing substance in the urine sample.

Fibrin strands woven into the clot structure are cleaved into soluble fibrin fragments, and then removed by macrophages. The action of fibrinolysis also serves to restore blood flow into the area that had been sealed off, helping to promote further healing. Fibrinolysis is mediated by a proteolytic enzyme called plasmin. Plasminogen is the inactive precursor form of plasmin that is found in plasma. Plasmin takes on fibrinolytic properties after activation, digesting both fibrin and fibrinogen. Inhibitors act to control the process, serving as a check and balance system for fibrinolytic activities.

The Human Immunodeficiency Virus type-1 (HIV) belongs to the Family Retroviridae.In HIV, RNA is the template for the synthesis of DNA. This differs from most cellular biochemistry in which DNA is used as the template for the synthesis of RNA.The enzyme that transcribes the RNA for the synthesis of DNA is called reverse transcriptase.Because of the enzyme's activity, HIV is known as a retrovirus - retro implying reverse.

In most cellular biochemistry, DNA is used as the template for the synthesis of RNA.In HIV RNA is the template for the synthesis of DNA. That is why the enzyme is called reverse transcriptase.Because of the enzyme's activity, HIV is known as a retrovirus - retro implying reverse.

Once the capsid and p24 and p17 have been stripped away, an enzyme complex known as reverse transcriptase is released.One of the enzymes in this complex is DNA polymerase. It synthesizes a single-stranded DNA copy using one of the HIV-RNA molecules as a template.Another enzyme in this complex, called ribonuclease, then destroys the original RNA molecules while the DNA polymerase synthesizes another single-stranded DNA molecule, this time using the first DNA copy as the template.The result is a double-stranded DNA molecule.

Three separate loci (ABO, Hh, and Se) contain the genes that control the location and occurrence of the A and B antigens. Hh and Se genes are closely linked on chromosome 19. The precursor substance is acted upon by the H gene and is converted to H substance. The product of the H gene is an enzyme fucosyltransferase, responsible for attaching fucose to the terminal galactose of the precursor substance on the RBC membrane and thus forming H substance. There are only two recognized alleles at this locus: the active form, H, and an amorph, h. The H gene is a high-incidence gene. People who inherit hh are extremely rare. Since the h gene is amorphic, it does not act on the precursor substance.

Antibody - A modified type of serum globulin synthesized by lymphoid tissue in response to antigenic stimulus. By virtue of specific combining sites each antibody reacts with only one antigen. Anucleate - Having no nucleus. Azurophilic granules - The well-defined large reddish granules (lysosomes) which may be present in large lymphocytes. They are called "azurophilic granules" because they stain blue with the azure stains which were originally used. Basophilic granules - Specific granules present in the cytoplasm of basophils. These granules are large and stain purple-black due to their strong affinity for basic stain. B-cell - Bone marrow derived lymphocytes which produce humoral antibodies. Biconcave - Having two concave surfaces. Cellular Immunity - The capacity of a small proportion of lymphoid population to exhibit response to a specific antigen. Chromomere - The centrally located granular portion of the platelet. Clone - A population of cells descended from a single cell. Delayed Hypersensitivity - (part of cellular immunity) that develops slowly over a period of 24-72 hours after an antigenic stimulus. It consists of an accumulation of cells around small vessels and/or nerves. Example: Tuberculin skin test reaction. Digestive Enzyme - A substance that catalyzes or accelerates the process of digestion. Eosinophilic Granules - Specific granules present in the cytoplasm of eosinophils. These granules are large, refractile spheres which stain reddish-orange due to their strong affinity for acid stain. Erythrocyte (red blood cell, RBC) - One of the elements found in peripheral blood. Normally the mature form is a non-nucleated, circular, biconcave disk adapted to transport respiratory gases. Fixed Macrophage - A phagocyte that is non-motile. Free Macrophage - An ameboid phagocyte present at the site of inflammation. Graft Rejection - A transplanted tissue that is rejected by the body's antibodies. Graft vs. Host Reaction - A complication that occurs when an implanted piece of tissue, which contains antibodies, rejects the host's tissue. Granulocyte - A leukocyte which contains granules in its cytoplasm, i.e., neutrophilic, eosinophilic, or basophilic granules. Half-life - is the length of time it takes for half of the cells circulating at a given time to leave the blood for the tissues. Hemocyte - Any blood cell or formed element of the blood. Hemostasis - A mechanism of the vascular system to arrest an escape of blood. It involves an interaction between blood vessels, platelets, and coagulation. Heparin - A mucopolysaccharide acid which, when present in sufficient amounts, functions as an anticoagulant by inhibiting thrombin. Histamine - A powerful dilator of capillaries and a stimulator of gastric secretions. Humoral Immunity - Acquired immunity produced after response to an antigenic stimulus in which B cells produce circulating antibodies. Hyalomere - the clear, blue non-granular zone surrounding the chromomere of a platelet. Immune Response - The interaction of a cell and an antigen that results in a proliferation of the cell and a capacity to produce antibodies. Isotonic Fluid - A fluid whose elements have an equal osmotic pressure. Leukocyte (white blood cell, WBC) - One of the formed elements of the blood; involved primarily with the body's defense. Lysosome - A microscopic body within cell cytoplasm; contains various enzymes, mainly hydrolytic, which are released upon injury to the cell. Megakaryocyte - A giant cell of the bone marrow from which platelets are derived. Mononuclear - A cell having a single nucleus.

The following is a list of enzymes for which known mutations have been associated with clinical effects. Enzymes Substrates (Drugs) Acetylaldehyde dehydrogenase Alcohol Acetylcholinesterase Succinylcholine Alcohol dehydrogenase Alcohol Dihydropyrimidine dehydrogenase Fluorouracil CYP2C9 Warfarin, phenytoin, losartan CYP2C19 Diazepam, omeprazole (Prilosec) CYP2D6 Many antidepressants, opioids, antiarrhythmics Glucose-6-phosphate dehydrogenase Aspirin, quinidine N-acetyltransferase Procainamide, isoniazid Thioprine methyltransferase 6-mercaptopurine UDP-glucuronosyl transferase Acetaminophen, tolbutamide, irinotecan

When discussing PGx, we classify a person according to his/her phenotype (metabolic capacity for a given enzyme).A poor metabolizer (PM) is a person who lacks the functional enzyme and therefore exhibits decreased metabolism of drugs. This person would require lower doses of a drug that is metabolized by that enzyme. A PM who receives a standard dose is more likely to experience unwanted side effects or toxicity. A PM can also experience diminished effects with drugs that need to be metabolized to active compounds by the enzyme in question.An ultrarapid metabolizer (UM) will require a higher dose than usual since he/she will eliminate the drug more quickly. A UM may be resistant to standard treatments, and it may take some time to adjust the dosage before therapy is achieved.An intermediate metabolizer (IM) has one wild-type (normal) copy of the gene and one absent or dysfunctional copy. The IM group is very heterogeneous.A person with normal enzyme activity is referred to as an extensive metabolizer (EM). This person should respond to standard dosages of a drug. Most people are EM's. This is the population in which most dosing regimens have been worked out in clinical trials.

CYP2D6 has received the most attention: It is estimated that about 25% of common drugs are metabolized by CYP2D6. CYP2D6 accounts for only about 1% of all CYP450 enzymes, but it is important in the metabolism of about 100 drugs. There are more than 80 genetic variants that have been described in the CYP2D6 gene. The normal, wild-type allele displays normal metabolic activity whereas some of the variant forms have enhanced or diminished activity. The variants can be grouped generally according to the resulting alterations in protein function. The groupings correlate with four major enzyme metabolic capacities (phenotypes): poor, intermediate, extensive (normal), or ultra-rapid metabolizers.

G6PD deficiency occurs in the same geographic distribution as malaria. It has been theorized that enzyme deficient cells are more resistant to malarial parasites than normal cells.When hemolysis is triggered, the appearance of the red blood cells is modulated by activity of the spleen.Spherocytes, schistocytes, and nucleated red blood cells may appear in the peripheral blood.Denatured hemoglobin removed by an active spleen may leave bite cells, identified by the arrows in this photomicrograph, suggesting the presence of G6PD deficiency.

A microcyte with normal hemoglobin content (one-third of central pallor) can be seen in the center of this field, just below and to the left of the lymphocyte. Since many of the other cells in this field are normal or larger than normal, the MCV would be within the normal range although the diameter and volume of this individual cell would be lower than normal. This type of microcyte can be seen in some hemolytic anemias and the rare enzyme deficiency, pyruvate kinase deficiency anemia.

Round cells in semen are of two types: immature sperm and white blood cells. To determine the percentage of white blood cells (specifically granulocytes) a special leukocyte screening test must be done. This test involves staining for the peroxidase enzyme present in the granulocytes.The 1999 WHO manual contains a protocol for doing this test (Appendix III). There is also at least one test kit on the market for this assessment (Leukoscreen: Bioscreen, Inc.).Laboratories with particular expertise in doing CBC and assessing granulocytes in stained blood smears may be able to do a differential count by this method rather than using a biochemical test for leukocyte screening.

If the specimen is more viscous than normal, it may be difficult to dilute it or to load it onto counting chambers in the undiluted condition. In this rare situation the semen may need to be manipulated to reduce the viscosity before a count is done. One method to do this is to repeatedly pipet the specimen up and down with an equal volume of culture medium. Care must be taken to avoid foaming. Other methods include enzyme digestion, for example with bromelain at a concentration of 1 gm / liter, or addition of a small amount of emulsifier, such as Alevare or chymotrypsin. Any manipulation of this type must be recorded on the report sheet. Calculation of the number of sperm per milliliter will also have to be corrected for any dilution.

In this photograph of blood cells from yet another submitted slide, we find cells resembling lymphoblasts with increased nuclear/cytoplasmic ratios and dense, finely meshed nuclear chromatin. In addition, note the extrusion of delicate strands of cytoplasm from the outer cell membranes (blue arrow). These are cells connoting hairy cell leukemia (HCL). Under scanning electron microscopy, the cytoplasmic extensions appear to be either slender microvilli or delicate pseudopods. The most helpful confirmatory finding is the detection of acid phosphatase isoenzymne 5 in the cytoplasm of suspected hairy cells by staining. The enzyme concentrates primarily in golgi bodies and in the nuclear membrane and its staining is not inhibited by the addition of tartrate. Stated in another way, hairy cells on the peripheral smears are detected by their staining positively for tartrate-resistant acid phosphatase. Be suspicious of HCL if marrow resists aspiration-a consequence of reticulin fibrosis of the marrow in HCL.