Chemical Information and Courses from MediaLab, Inc.

In addition to chemical components, a few cells are also found in normal CSF. In an adult, 0 - 5 WBC/µl is considered normal. Children will have slightly higher cell counts. Up to 30 WBC/µl is within normal limits for newborns. Lymphocytes account for 60 - 100% of these cells.

The physician orders tests based on the disorder suspected. For example, CSF may be analyzed for one or more of the following chemical components: sodiumpotassiumchloridemagnesiumproteinglucosecalciumcholesterolcreatininelactic acid dehydrogenase (LDH)phosphorusureauric acid

Use a fresh, well-mixed uncentrifuged urine. Hold the reagent strip by the opposite end from the test areas and dip the stick into the specimen so that all test areas are immersed in the specimen. Remove the stick immediately. Prolonged immersion in the sample may wash out the test reagents. Hold strip in a horizontal position and run the edge of the strip against the rim of the urine container or touch the long edge of the strip to absorbent toweling to remove excess urine (do not blot the strip). Maintain the strip in a horizontal position to prevent mixing of reagent chemicals. Observe the reagent pads at the specified time periods. Color changes that occur after the stated maximum read time are not valid. Hold the strip close to the chart and compare the colors to read the results. A good light source facilitates accurate reading. Quality control procedures should be performed with each new lot of reagent strips and as often as required by the laboratory's procedure

No blood is found in the urine of healthy individuals although samples from menstruating females, frequently, but not always, test positive for blood. Hematuria is associated with renal or genital urinary disorders in which the bleeding is the result of irritation to the involved organs or trauma. Examples include renal calculi, pyelonephritis, glomerulonephritis, tumors, trauma or exposure to toxic chemicals or drugs and/or strenuous exercise. Hemoglobinuria may be due to the lysis of red cells within the urinary tract. If it is caused by intravascular hemolysis, the hemoglobin is then filtered through the glomeruli. In the normal individual, the hemoglobin molecule attaches to haptoglobin and in this way bypasses the kidney filtration system. When the hemoglobin/haptoglobin system is overwhelmed, as in cases of hemolytic anemia, severe burns, transfusion reaction, infection or strenuous exercise, hemoglobin passes into the urine.

Denaturing chemicals can be added to the acrylamides during formation of polyacrylamide gels. These additives keep the solutes or molecules in a denatured state during separation. Urea denatures double-stranded DNA to single-stranded DNA. A detergent, sodium dodecyl sulfate (SDS), denatures proteins. Adding SDS with heat denatures proteins to small, similar shaped particles and coats each so that protein structures are not reformed. SDS is usually added to the gel and the protein sample. Then the mixture of protein coated fragments moves through polyacrylamide gel pores with speed similar to a mixture of DNA fragments.

Keep the affected eye open using your fingers. Immediately begin flushing the eyes with water and continue for 15 minutes. Use an eyewash, safety shower, or water from the sink.Assist the victim by supporting the head so that water flows across the eyeball from the inside corner of the eye (nearest the nose), outward. This will prevent chemical from getting into the unaffected eye.Get immediate medical help.

If the chemical is a dry powder, first brush it off from the victim, taking care not to contaminate yourself, especially your eyes.Immediately flush exposed skin with large amounts of water.Remove contaminated clothing while continuing to flush the affected area with water.Continue flushing with water for 15 minutes or longer.Seek emergency medical attention.

The first specific, recognizable hemostatic mechanism is a process known as vasoconstriction, which is initiated by chemical signals stemming from a breach of the vasculature. Vasoconstriction, or vascular constriction, immediately reduces the quantity of blood flowing through the damaged area. Its action is the physical decrease in the size of the vessel, and the redirection of blood flow around, and away from, the damaged area. Vasoconstriction is akin to putting a clamp on a pliable piece of plastic tubing. A short process in terms of the overall time elapsed, the entire vascular response typically lasts less than one minute! Though fleeting, vasoconstriction is an exceedingly important hemostatic mechanism as it prepares the damaged vessel for subsequent repair activities.

Platelets have three primary functions: Maintenance of Vascular Integrity – Platelets contain chemicals within their granules that are vital to the normal growth and maintenance of the vascular system. Platelet Plug Formation – Platelets are the fundamental components of the physical barrier that initially fills the breach in the compromised vessel. Stabilization of the Platelet Plug – Inherent platelet stickiness acts as a strong bond between the platelet and the exposed subendothelium, as well as between platelets themselves. Fibrin strands will weave in amongst the bound platelets that make up the platelet plug, further compressing and solidifying the structure and creating a fibrin clot.

In summation, we have covered the following sequence of events which comprise primary hemostasis. The process begins with damage to a vessel wall, as blood flows outside the vasculature. The body responds with vasoconstriction, decreasing blood flow to the affected area. Platelets begin sticking to the damaged vessel walls. As the platelets stick, they release chemicals which signal other platelets to respond. As other platelets arrive, they begin sticking to one another, clumping together, forming a plug to fill in the breach. This plug, while strong, is a temporary fix, and must be reinforced with fibrin strands to effectively fill the breach during the vessel repair process. Construction of the fibrin strands occurs during secondary hemostasis, our next topic to be covered.

The formation of fibrin involves three interconnected biochemical pathways; the intrinsic, extrinsic, and common pathways. These pathways allow for the interaction of coagulation factors via a finely tuned sequence of chemical processes, where the factors themselves control the activity of the pathway. Most coagulation factors are stimulated and activated by the preceding factor , hence the term, "coagulation cascade." Since factor activation requires the activation of a preceding factor, a deficiency in the functionality or availability of any factor would seriously impact the effectiveness of the coagulation process. Factor deficiencies do occur, however, and often lead to impaired vascular repair and depressed hemostatic activity.

This course began with a discussion on homeostasis, the body’s desire to maintain a status of physiological equilibrium. Our inborn system of chemical checks and balances, activators and inhibitors, can be disrupted by numerous factors, two of the more common being acquired disease states and disorders passed on to offspring via inheritance. In regard to coagulation, both disease status and genetics can adversely affect the functionality of many hemostatic processes. Impaired hemostatic mechanisms, be it acquired in cases of disease or inherent, may result in situations of either hemorrhage or thrombosis. A situation of hemorrhage, or bleeding external to the vasculature, most often stems from physical vessel trauma, but may also arise from a wide variety of disease states. Thrombosis does not require physical trauma, and is the activation of hemostatic processes at an inappropriate time in an inappropriate place, and may arise from a number of inherited or acquired disease states. The following pages are intended to serve as an introduction to some of the more commonly encountered coagulation disorders.

Detection techniques can vary in both direct and amplified methodologies and can include labeling either the probe or the target molecule of interest:Chemiluminescence: Release of light energy at the end of a chemical reaction that is detected by a luminometer. Uses a label such as acridinium ester. Electrophoresis: movement in a matrix such as a gel that is caused by an electrical field.Enzyme: Uses enzyme and substrate principles to label the appropriate target or probe. Can be combined with fluorescence or dyes for detection.Fluorescence: Molecules that emit light at a longer wavelength when excited at a shorter wavelength. Detection techniques include fluorescent staining of nucleic acids as well as fluorescent labeled probes that are measured in a fluorometer or with fluorescent polarization.Radioactivity: Uses a labeling technique where the radioactive label is then measured in a scintillation counter. The earliest assays utilized radioactive decay.

Like many other viruses, the HIV has a lipid membrane that covers the capsid. This envelope is acquired when the virus leaves a cell after replication. The HIV envelope has projections known as spikes, which contain specific chemical components that may assist the virus when it attaches to other cells.

Like many other viruses, the HIV has a lipid membrane that covers the capsid. This envelope is acquired when the virus leaves a cell after replication. The HIV envelope has projections known as spikes, which contain specific chemical components that may assist the virus when it attaches to other cells.

Targets the terrorists might use include high-profile landmarks, airports, plus civilian and military government facilities. They might also target large public gatherings such as bowl games, our water and food supplies, even public utilities. In addition, the terrorists may attempt to spread fear by sending explosives, chemical or biological agents through the mail.

Potential biological and chemical agents that might be used as weapons of mass destruction (WMD) are numerous, and preparing the nation to address these dangers is a major challenge.  Early detection of and swift response to biological and chemical terrorism is crucial. This requires increased biological and chemical awareness by front-line health-care providers because they are in the best position to report suspicious illnesses.

Chemical warfare agents are poisonous vapors, aerosols, liquids, or solids that have toxic effects on people, animals or plants. They can be released in a number of ways such as by bombs or sprayed from aircraft. Some chemical agents are odorless and tasteless. They can have an immediate effect (such as a few seconds to a few minutes), or a delayed effect (from several hours to several days). Even though chemical agents have the potential to be lethal, they are difficult to deliver in lethal concentrations, particularly in outdoor situations where they tend to dissipate rapidly.

They are relatively inexpensive to produce.The components are often cheap and easily accessible.They are easy to use.There are multiple means of delivery.The fear factor.They can have a psychological as well as physical impact, causing pain for the victims and panic for the survivors.

Currently there are over 60 territorial and metropolitan public health laboratories that are members of the chemical component of the LRN. A designation of Level 1, 2, or 3 defines their network participation.

In addition to the responsibilities listed for Level 3, over 40 laboratories also participate in Level 2 activities. At this level, laboratory personnel are trained to detect exposure to a limited number of toxic chemical agents in human blood or urine, the analysis of cyanide and toxic metals in human samples, for example.

A chemical attack involves poisonous vapors, aerosols, liquids, or compounds. A terrorist might spread harmful chemicals with a bomb; spray from aircraft, boats, or vehicles; pour the chemicals into water or onto food; or leave a container of poisonous chemical in a confined public space.

Control materials are made to match patient samples in physical and chemical characteristics. Control samples are often made with biological material.Control samples are tested in the same way as patient samples. If the results from testing a control sample are not within the acceptable ranges, we assume there has been a problem in the test procedure, equipment, or the samples themselves. There are many criteria for rejecting a test based on the control samples measurements; these criteria will be detailed further in a later section.Patient results are not reported until the cause of the problem has been found, the problem resolved, and the controls re-run to verify that everything is working normally.

Public health laboratory scientists are also regulated by the Board. The table below outlines the various requirements for applicants to receive licensure for a public health laboratory. Public Health Laboratory RequirementsDirectorFulfill the same requirements as a clinical laboratory directorSupervisorBe certified by National Registry in Clinical Chemistry or American Society for MicrobiologyBe licensed as a technologistHave five year's relevant experiencePass the state examTechnician (microbiology)Have a Bachelor's degree in one of the biological sciencesObtain American Society for Microbiology or the National Registry in Microbiology Certification in Public Health Microbiology Technician (chemistry)Have a Bachelor's degree in one of the chemical, biological, or physical sciencesObtain National Registry of Clinical Chemistry Certification in Public Health ChemistryTechnician (conditional)Have a Bachelor's degree in one of the chemical or biological sciencesPerform tests only under the direct supervision of a licensed pathologist, director, supervisor, or technologist.Receives a conditional two-year license, which may be renewed only once A license from the Board of Clinical Laboratory Personnel allows you to work in a public health laboratory at the same level and specialty.

Meets one of the following:Bachelor's degree in clinical laboratory, chemical or biological science plus:Completion of a medical technologist training program ORThree years of laboratory experience, at least one of which must be in the applied-for specialtyAssociate's degree plus:Florida technician's license and completion of a technician level medical laboratory training program ORFive years of laboratory experience, at least one of which must be in the applied-for specialtyPasses an examination in one or more specialtiesCompletes one hour of HIV / AIDS continuing educationCompletes two hours of medical errors continuing education

Specialists in immunohematology perform all testing prior to blood transfusions and work to prevent transfusion infections. They also investigate any post-transfusion reactions. This specialty includes all lab procedures performed in the specialty of histocompatibility. Specialists in clinical chemistry analyze body fluids such as blood, urine, and spinal fluid to determine the chemical makeup, including the amount of carbohydrates, proteins, enzymes, and trace elements. The special covers urine microscopics and chemical evaluation of the liver, kidneys, lungs, heart, and other vital organ systems. This specialty also covers all testing performed in the specialties of radioassay and blood gas analysis. Specialists in blood banking can perform all immunohematology testing as well as testing from the specialties of clinical chemistry, hematology and serology/immunology that relates to donor blood. Clinical laboratory personnel who are licensed in the specialties of immunohematology, clinical chemistry, hematology, and serology / immunology may perform all tests in the blood banking specialty.

Erythrocytes are produced in the bone marrow and released into the peripheral blood where they may remain for approximately 120 days before senescence.Their main function is the transport of the respiratory gases (oxygen and carbon dioxide) between the lungs and body tissues.Each erythrocyte can be thought of as an "envelope" containing hemoglobin.Each hemoglobin molecule contains iron which has a high affinity for oxygen.As a result, when an erythrocyte passes through one of the capillaries of the lungs, it picks up oxygen.The oxygen is transported through the blood to the tissues where it is released.Carbon dioxide from the tissues then diffuses into the RBC where it undergoes chemical changes.About 70% of the altered carbon dioxide diffuses into the plasma, 25% binds to the hemoglobin molecule, and 5% goes into simple solution within the red cell.In each of these three ways carbon dioxide is transported from the body tissues back to the lungs, where it is released.

This training program is designed for your benefit and protection. In it you will receive the information necessary to ensure your familiarity with the chemicals in your workplace and how best to handle them.

There was no guarantee that workers would be told about the chemical hazards they might face on the job. Container labels and warning sheets did not always give enough information on potential hazards, what to do in an emergency, or where to turn for help.

In 1987, OSHA issued a regulation to help control workplace exposure to chemicals. This regulation is called the Hazard Communication Standard, but is more commonly known as Haz-Com, or the Right-to-Know Law.

Chemicals have to be treated with respect. Many can cause injury or illness if not handled properly.

Every chemical container is labeled by the manufacturer. The format of the label will differ from company to company. The label must contain similar types of information to meet the OSHA and DOT regulations. The label makes it easy for you to find a chemical's possible hazards. The basic steps to protect yourself against the chemical's hazards are listed on the label.

The label will also describe: Any important storing or handling instructions. The personal protective equipment you must wear when working with the chemical.

The National Fire Protection Agency (NFPA) ranks chemicals numerically according to the hazards associated with them and displays these numbers in the NFPA symbol. They indicate: Health hazards Fire hazards Reactivity Special hazards related to a chemical

The red diamond on the top of the NFPA symbol represents fire hazards. 0 = the chemical will not burn and thus has no flash point 1 = the flash point > 200°F 2 = the flash point < 200°F 3 = the flash point < 100°F 4 = the flash point < 73°F

The white diamond at the bottom of the NFPA symbol is the special hazard section. If the chemical reacts with water, a strike-out W (W) will appear in this section. OX means the chemical is an oxidizer. COR means the chemical is corrosive. The radioactivity symbol indicates that the chemical is radioactive.

Like the manufacturer's label, the first section lists specific information about the chemical, including: Chemical name Name under which it is shipped Manufacturer's name, address, and phone number

What makes up the chemical. What the 8-hour occupational exposure limit is for the threshold limit value, or TLV. On some MSDS, the short term exposure limit (or STEL) for 15 minutes will also be listed.

Physical and chemical characteristics of the chemical include: Boiling point Specific gravity Solubility Appearance Odor

Describes the stability of the chemical, or how it reacts with other substances. Lists which substances and situations should be avoided to prevent chemical reactions.

Further information: Manufacturer product number An emergency phone number CAS identification number The DOT shipping name and hazard class The chemical family name and synonyms The chemical's formula and molecular weight

Laboratory safety includes a number of precautions designed to protect you and your coworkers. Remember that: eating drinking smoking applying cosmetics or lip balm are forbidden in areas where chemicals are present.

After working with chemicals and removing your gloves, wash your hands thoroughly.

If there's a fire in the laboratory and chemicals are involved, there's a chance that some of the chemicals could react adversely with water. For that reason, the best fire extinguishers to use are ABC fire extinguishers. Using water to extinguish a chemical fire could actually fuel the blaze or cause chemicals to splatter.

Also remember to: Learn basic first aid measures. Read chemical labels. Read MSDS. Follow warnings and instructions. Use the correct protection. Practice sensible, safe work habits. Be knowledgeable about your laboratory's Chemical Hygiene Plan and the location in your laboratory of all reference materials on the hazards, safe handling, storage, and disposal of hazardous chemicals, including the location of Material Safety Data Sheets.

Manufacturers are required to label appliances and instruments with electrical ratings including voltage, frequency, current, and/or wattage of the device and precautionary statements if applicable. Operating and safety instructions are provided with electrical equipment. It is prudent for personnel to familiarize themselves with this information before using the equipment. Personnel should be aware of the hazards associated with the use of defective electrical equipment. Defective equipment should be tagged and repaired or discarded. Keep liquids, chemicals, and heat sources away from electrical outlets and cords.

Class B fires involve flammable liquids including chemicals and grease. Class B fires can be extinguished by using a carbon dioxide (CO2) extinguisher or an all purpose dry chemical extinguisher (ABC). Never use water on a Class B fire since this will only increase the hazard. Use care in extinguishing a Class B fire as this type of fire can flash back and reignite after being extinguished.

Class C fires involve electricity. Use a carbon dioxide extinguisher or any all purpose dry chemical extinguisher (ABC). Never use water on a Class B or C fire since this will only increase the hazard.

1987 Haz-Com Standard is designed to help control employee exposure to chemicals on the job.1990 Chemical Hygiene Standard is specifically designed to meet the needs of laboratories with large varieties of chemicals, and to require specific training for laboratory employees.1992 Formaldehyde Standard is specifically for employees that work with formaldehyde. The goal was to reduce the risk of formaldehyde overexposure by establishing safe exposure limits.

1987 Haz-Com Standard (29 CFR 1910.1200) is designed to help control employee exposure to chemicals on the job. 1990 Chemical Hygiene Standard (29 CFR 1910.1450) is specifically designed to meet the needs of laboratories with large varieties of chemicals, and to require specific training for laboratory employees. 1992 Formaldehyde Standard (29-CFR 1910.1048) is designed specifically for employees who work with formaldehyde. The goal of this standard is to reduce the risk of formaldehyde overexposure by establishing safe exposure limits.

Engineering controls must be established to reduce formalin exposure to the lowest possible level. In most cases, chemical fume hoods or/and ventilated grossing stations serve as the primary engineering controls to reduce formaldehyde vapors. Rooms in which formalin is used may also require special direct exhaust ventilation. Formaldehyde should be dispensed or used in a chemical fume hood or other appropriately ventilated and approved work area. Check your laboratory's policies and procedures to be sure you use the engineering controls provided, as well as the required personal protective equipment.

The liver plays a major role in converting lipophilic nonpolar molecules (drug molecules) to more polar, water-soluble forms through a series of enzymatic reactions. Drug molecules can be modified by either phase I or phase ll reactions. Phase I reactions alter chemical structure by oxidation, reduction, or hydrolysis. Phase ll reactions conjugate drugs to create products that are water-soluble.

Clinical Chemistry: Theory, Analysis, Correlation, 4th Edition. Lawrence A. Kaplan, Amadeo Pesce, Steven Kazmierczak. New York: Mosby, 2002.FDA Clears Genetic Lab Test for Warfarin Sensitivity. FDA News. U.S. Food and Drug Administration. Available at http://www.fda.gov/bbs/topics/NEWS/2007/NEW01701.html. Accessed June 3, 2008.Goodman & Gilman's The Pharmacological Basis of Therapeutics, 11th Edition. Laurence Brunton, John Lazo, Keith Parker. McGraw-Hill, 2005.Tanaka E, Terada M, Misawa S. Cytochrome P450 2E1: it's clinical and toxicological role. J Clin Pharm Ther. 2000 Jun;25(3):165-75.The Chemistry of Mind-Altering Drugs: History, Pharmacology, and Cultural Context. Daniel Perrine, American Chemical Society Publication, 1996.Tietz Textbook of Clinical Chemistry and Molecular Diagnostics, 4th Edition. Carl A. Burtis and Edward R. Ashwood, eds. Philadelphia: WB Saunders, 2005.

Rubber stoppers of blood collection tubes are color coded. Each type of stopper indicates a different chemical additive (usually an anticoagulant to prevent clotting), or a different tube type.

Controls must resemble as closely as possible the human samples they emulate.For hematology analyzers, controls need to have the same consistency and color as human blood. Likewise, serum controls need to have similar amounts of chemicals to those found in human serum.

If stains and technique are adequate, S. aureus should be Gram positive (blue) and E. coli should be Gram negative (pink). If control slides do not react appropriately, reliable results cannot be assured for the specimen smears. Check stains and technique and prepare more control smears until proper results are achieved, then remake and stain the new direct smears. If it is impossible to prepare a new smear, the poorly stained smear may still be salvaged. Remove immersion oil from the smear using xylol. Use appropriate procedures and personal protective equipment when using xylol, since it is hazardous chemical. If the smear is underdecolorized, repeat the decolorization and counterstain steps. If the smear is overdecolorized, the slide should be stained again.

Schistocyte is a general term for a fragmented red blood cell that may assume various shapes, some with horn-like projections (keratocytes), triangle-forms (triangulocytes), and helmet shapes, as illustrated in the upper photograph. Schistocytes are formed when erythrocytes are forced through a vessel blocked with interlacing fibrin strands and the red cells are sliced into fragments. True schistocytes are devoid of central pallor. These damaged cells continue to circulate while healing their torn edges. Finally, they are removed by the spleen. Bite cells (lower photograph) appear when an abnormal hemoglobin aggregate (Heinz body) is nibbled out of a red cell's cytoplasm by the spleen leaving a bitten apple appearance. Glucose 6-PD deficiency secondary to chemical poisoning or injury by oxidant drugs are settings for Heinz body formation, and the telltale bite cells remain as evidence. Hemolytic anemia associated with severe liver disease is another setting where bite cells are formed.

Examples of conditions in which spherocytes can be seen include hereditary spherocytosis and immune hemolytic anemias (i.e., ABO incompatibility). Spherocytes can also form in conditions where there has been a direct physical or chemical injury to the cells. An example would be a smear from an individual who has suffered severe burns. In hereditary spherocytosis, a condition where spherocytes are numerous, the MCHC value will be at the upper limits of normal, or about 36. The identification of spherocytes on the smear of a patient with hereditary spherocytosis can aid significantly in the diagnosis of the disorder. In Artifactual spherocytes can appear when blood is stored for a prolonged period of time.

Each tube used for blood collection is labeled by the manufacturer with important information. This information includes: tube volume in milliliters (mL), expiration date, lot number and, if applicable, the type of additive that is in the tube. Tube volume: Each tube contains a vacuum that allows a specific amount of blood to enter the tube. In a tube that contains an anticoagulant, the amount of blood that is drawn into the tube will establish the correct blood to anticoagulant ratio. Tubes not filled to the correct volume (over-filled or under-filled) may cause inaccurate test results. Expiration Date: An expiration date is stamped on all blood collection tubes. The tube manufacturer determines this date based on its studies of vacuum maintenance and anticoagulant effectiveness. The expiration date should be checked routinely; tubes that are past the expiration date should be discarded.If a blood collection tube is used past its expiration date, the vacuum may not draw the amount of blood needed to fill the tube completely. Short-filled tubes may not be acceptable for testing and the specimen would have to be recollected. If the tube contains an anticoagulant, it may not work effectively (may not prevent the blood from clotting). Lot Number: A lot number listed on the tube identifies a specific group of tubes that were manufactured at the same time. This information is important to know if a problem is identified with several collection tubes. If the defective tubes are all part of the same lot number, the manufacturer should be notified for replacement of the tubes. Additive: Most blood collection tubes contain a type of additive or chemical that, when mixed with the blood, will yield a specimen acceptable for testing. The various types of additives that are contained in blood collection tubes are discussed on the following page.

Semen is produced as a combination of secretions from the different regions of the male reproductive tract. Each fraction differs in chemical composition and function. The combination of these fractions during ejaculation results in the optimal environment for transporting sperm to the endocervical mucus in the female. Spermatozoa are produced in the testes. They mature in the epididymis. The testes also produce testosterone and inhibin.Fluid from the seminal vesicles accounts for approximately 70% of semen volume. The seminal vesicles are the source of fructose in semen. Fructose is used by the spermatozoa as an energy source.The prostate gland supplies about 20% of the volume of semen. Its fluids include acid phosphatase and proteolytic enzymes that lead to coagulation and subsequent liquefaction of semen. The prostate also contains most of the IgA found in semen.The bulbourethral gland produces mucoproteins that make up about 5% of the volume of semen.

Examination of a fresh urine specimen provides the best results. If a specimen cannot be examined immediately, it may be refrigerated for up to 12 hours. Refrigeration prevents decomposition of casts, cells and the overgrowth of bacteria. The urine sediment elements begin to lyse after 1-3 hours at room temperature. Although the most commonly received urine specimen is the random urine collection, the specimen of choice for urinalysis is the first morning urine. The first morning urine is more concentrated and allows for the detection of substances which may not be present in a more dilute random sample. Once the physical and chemical characteristics of the urine have been determined, the microscopic exam is performed on the sediment.

Calcium oxalate crystals have a characteristic octahedral or envelope shape. Fine focusing will cause the "x" to be refractile. Size may vary from extremely small to quite large. They are associated with diets high in oxalic acid or chemical toxicity. Occasionally calcium oxalate crystals are dumbbell or oval in shape.

A basophil and a small lymphocyte are compared in the same field of the upper photograph, A single basophil is shown in the lower photograph.The cytoplasmic granules of the basophil are larger than the granules of toxic granulation.They contain chemical mediators of immediate hypersensitivity, and are found in the cytoplasm and overlying the nucleus (better seen in the lower photograph). Basophilic granules stain metachromatically with toluidine blue indicating the presence of acid mucopolysaccharide or proteoglycans, both thought to be heparin or heparin-like substances.Basophils are related to tissue mast cells, each involved in hypersensitivity responses and following anaphylactic episodes.Under the stimulation of complement components C3a and C5a, many mediators are released from the basophil granules, including histamine, heparin, and eosinophil chemotactic factors of anaphylaxis, or ECF-A.Basophils are the least common neutrophils in the peripheral blood, comprising 2% or less of the differential count.The presence of large granules of irregular size in basophils and the admixture of eosinophilic granules may indicate dysplastic changes associated with myelodysplastic disorders and leukemia.