Acetic Information and Courses from MediaLab, Inc.
These are the MediaLab courses that cover Acetic and links to relevant pages within the course.
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| More on Undiluted Specimens In an undiluted specimen, count and differentiate red cells and white cells at the same time. You can count red cells on a hand counter and use the differential counter for white cells.
If you cannot differentiate white cells from red cells in the undiluted specimen, a plain capillary tube may be filled with crystal violet acetic acid diluent which is subsequently expelled from the tube. A very thin coating of the diluent will remain on the inside of the tube. CSF is drawn halfway up into the tube, which is then rocked back and forth to mix. The hemacytometer is then filled with the fluid containing stained white blood cells and lysed red cells.
If cells are numerous and overlapping and it is necessary to focus through several planes in order to see all of the cells, a dilution must be made.
When macroscopic appearance is turbid, milky or bloody, a significant dilution is usually necessary. | View Page |
| Diluting Fluids There are several diluents that may be used for CSF counts. Normal saline should be used to make dilutions for total cell counts. Diluting fluids for WBC counts include:crystal violet/acetic acidgentian violet/acetic acidtoluidine blue 0 and saponinThese fluids stain the white cells and lyse the red cells. The red cell count can be obtained by subtracting the white cell count from the total count.
Low power (10x) may be used for the total count while the high power objective (40x) is suggested for the white cell count, especially if the white cells are to be differentiated into segs, lymphs and monocytes.
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| Which of the following diluting fluids are suitable for spinal fluid counts? | View Page |
| Confirmatory Testing for Protein Semiquantitative tests are used in some laboratories to confirm the presence of protein in the specimen when the result is positive on the urine dipstick. Tests that are used for confirmation include: sulfosalicylic acid (SSA); heat and acetic acid; nitric acid ring test; and Roberts' Ring Test. Any one of these procedures may be used for confirmation of the presence of protein. A protein dipstick result that is greater than a trace may be an indication of proteinuria. | View Page |
| Sulfosalicylic Acid Test (Exton's Modification) There are several acids which can be used to precipitate proteins - sulfosalicylic, trichloroacetic, nitric, and acetic acids. Sulfosalicylic acid (SSA) is the most frequently used acid test because it does not require the use of heat. Exton’s reagent is 5% sulfosalicylic acid in a solution of sodium sulfate. Exton (1925) found that adding sodium sulfate to the SSA causes a more uniform precipitate to be formed. To perform the SSA procedure mix equal parts of patient urine and the reagent. Rate the amount of turbidity according to the following scale: | View Page |
| Credibility of Results The pH of the urine must be approximately 7 or less in order to avoid false negatives with this test. If the pH exceeds 7, add 33% acetic acid dropwise to acidify the specimen to a pH of 7. If the specimen is cloudy, it should be centrifuged before SSA reagent is added. Daylight or fluorescent light is recommended when interpreting results. Quality control checks should be performed by testing known negative and positive specimens or controls. | View Page |
| The screening test most commonly used to detect Bence-Jones protein in urine is: | View Page |
| Heat and Acid Test for Urinary Protein The heat and acetic acid test is another semiquantitative test used to confirm the presence of protein in urine. It is more sensitive than the SSA test because the pH of the sample is brought close to the isoelectric point of proteins. However, this test is sometimes considered too sensitive because it can detect trace amounts of protein which are considered normal. The heat and acetic acid test gives false positive results with inorganic iodides, benzoin, tolutamide, and proteoses, similar to the SSA test. Bence-Jones protein consists of dimers of either kappa or lambda light chains from immunoglobulins. This abnormal protein is most often associated with multiple myeloma, but can also be found in cases of lymphoma, macroglobulinemia, leukemia, and other malignancies (Balant and Fabre, 1978). Testing for Bence-Jones protein is not part of the routine urinalysis. However, if Bence-Jones protein is suspected, the heat precipitation test or immunoelectrophoresis can be performed on a urine specimen. The heat precipitation test is based on the protein’s unusual solubility properties. Bence-Jones protein precipitates at temperatures between 40ºC and 60ºC (56ºC optimum), but dissolves again at 100ºC. Upon cooling, the precipitate will reappear around 60ºC and will dissolve again below 40ºC | View Page |
| Types of Support Media For electrophoretic separation of solutes, the sample of solutes is placed on a gel or membrane in contact with buffer for separation. Common gels are cellulose acetate, agarose, and polyacrylamide gels. These gels are formed into sheets, slabs, or inserted into columns or tubes. The gel can be positioned horizontally or vertically.Cellulose is chemically reacted with acetic anyhdride to form a cellulose acetate gel. Because cellulose requires soaking before sample application and a clearing step for detection of separated solutes or bands, agarose gel is more often used than cellulose acetate gel for clinical electrophoresis. | View Page |
| Fixation and Processing of the Biopsy Specimen The biopsy specimen is usually fixed in Zenkers’ acetic solution (5% glacial acetic acid; 95% Zenkers) for 6-18 hours or B-5 fixative for one to two hours. Excessive time in either fixative makes the tissue brittle, then briefly decalcified.
The tissue is processed together with other tissues, and is embedded in paraffin and cut at 4 µm and stained with hematoxylin and eosin (H&E) and Perls’ Prussian blue iron stain, and other special stains as indicated. | View Page |
| Red Blood Cells versus Yeast In this field both red blood cells and yeast are present. Since red blood cells are readily hemolyzed by dilute acetic acid, a drop is allowed to flow under the edge of the coverslip. The acetic acid lyses the red blood cells, leaving only the remaining yeast. | View Page |
| Lysis of Red Blood Cells with Acetic Acid This slide shows residual yeast after red blood cells have been lysed with acetic acid. | View Page |
| A urine specimen was delayed in transport to a medical laboratory. Upon examination of the urine sediment, the technologist cannot distinguish between bacteria and amorphous urates. Which of the following reagents would dissolve the crystals? | View Page |
| A 10% solution of acetic acid can be used to differentiate what from red blood cells? | View Page |
| A technologist is trying to enumerate the number of fat droplets in a urine sediment which also contains numerous red blood cells. Which of the following reagents would stain the fat droplets orange red? | View Page |
| White Blood Cells versus Cuboidal Epithelium A drop of dilute acetic acid enhances the nuclear detail of the white blood cells making them much easier to distinguish from the epithelial cells. | View Page |
| Amorphous Urates Amorphous urates can be dissolved in dilute sodium hydroxide. Amorphous phosphates will dissolve in dilute acetic acid. In either case, the bacteria will remain. | View Page |