topics / مواضيع

  A day book is ideal as it has the necessary ruled lines. In your record put the date, reference number, patient’s name, name of the referring doctor, investigations asked for, reports given and payment status (if privately owned laboratory). Laboratory Reporter An ideal laboratory computer program helps in reporting and recording diagnostic center, pathology lab and other diagnostic imaging fields. The program should also keep history records of the patients. It must have facilities of making and reporting profiles, e.g. lipid, renal, cardiac, hepatic and diabetic profile. A program can be called ideal if: FIG. 1.29: Serological water bath (Courtesy: Yorco Sales Pvt. Ltd) FIG. 1.30A: Incubator (Courtesy: Yorco Sales Pvt. Ltd) FIG. 1.30B: Hot air oven (Courtesy: Yorco Sales Pvt. Ltd) It Reduces Overload ¾ Avoids manual operations by printing booking slips, receipts, bills, envelopes, etc. ¾ Prints daily register of patients ¾ Prints rate lists ¾ Reports only the tests required and not

  Sterilization C H A P T E R The terms sterilization and disinfection are used to indicate the treatment of material so as to destroy or otherwise eliminate any living organisms present. However, the term sterilization is used where physical methods are used and disinfection is used where chemical agents are made use of. METHODS COMMONLY USED FOR STERILIZATION The methods used commonly in practice are: 1. Killing organisms by heat: Heat may be dry or moist 2. Destroying organisms by employing chemical antiseptics, e.g. lysol, phenol, perchloride of mercury, etc. 3. Removing organisms mechanically by filtration, e.g. Seitz, unglazed porcelain. Sterilization by Heat Adequate heat is the most certain and rapid method for sterilization. The time needed for sterilization is inversely related to the temperature of exposure—the higher the temperature, the shorter the time needed. High temperature kills bacteria by coagulating their proteins. Different types of bacteria show considerable diff

  a. Specimen bottles—with top screws, e.g. the universal type containers. b. Reagent bottles—have ground glass or plastic stoppers, available in different sizes and may be made of amber colored glass (Figs 1.21A and B). c. Drop bottles—fitted with special tops through which drops can be delivered (Fig. 1.22). 4. Funnels—used to hold filter papers when filtering fluids or for pouring liquids into narrow neck containers (Figs 1.23A and B). 5. Cylinders—used for measuring liquids, they have a pouring spot (Fig. 1.24). 6. Tubes—are of various sizes; of the test tube or centrifuge (conical) type, with or without a top rim (Figs 1.25 and 1.26). 7. Pipettes—are used to measure and deliver a given volume of fluid. FIG. 1.17: Conical flasks FIG. 1.18: Volumetric flasks FIGS 1.19A AND B: (A) Round bottomed flask and (B) Flat bottomed flask FIG. 1.20: Beakers A B Laboratory 25 FIG. 1.21A AND B: (A) Specimen bottles and (B) Reagent bottles A B FIG. 1.22: Drop bottles a. Volumetric pipettes—have a

  Importance 1. For identifying mycobacteria. 2. It is used extensively in fluorescent antibody techniques used in parasitology and bacteriology. FIG. 1.11: The principle of dark ground illumination 22 Concise Book of Medical Laboratory Technology: Methods and Interpretations 3. It is also used widely in histopathology of kidney, skin, etc. where immune/autoimmune basis of disease is expected. In fact, anything can be confirmed with high degree of sensitivity and specificity, if antibodies against it (later tagged with a fluorescent dye) can be produced. 4. Used widely in cytogenetics. Electron Microscope Basic Principle The resolution of the light microscope has been shown to be limited by the NA and the wavelength of light employed. As the degree of correction in glass lenses is very high, the main limitation is imposed by the light (e.g. half wavelength of light), giving a normal resolution of approximately 250 nm; and when UV light is used, a resolution of about 100 nm. By the subs

Condenser and Iris Condenser is a large lens mounted below the stage, with an iris and diaphragm. There may be 2 or more lenses. Its function is to deliver the light beam to the objective at a sufficiently wide angle. FIG. 1.8B: Digital microscope Microscope Optics Objective On objective quality, depends, the quality of the image. These are usually made up of more than one lens. On each objective is engraved the magnification power. Numerical Aperture Numerical aperture (NA) of the objective is important, for on this, depends, among other things, the amount of light which the lens passes and the detail which it can make visible, on which it is said to resolve. Oil Immersion Objectives They are used to avoid bending of light beam (with higher magnification). The oil used should have the same optical properties as glass, e.g. cedar wood oil. Liquid paraffin can also be used. Objective Aberrations With increasing magnification certain optical aberrations creep in: 1. Spherical aberration—

  which pass through the rest of the plate. Supposing that the specimen is suspension free fluid, the only light that reaches the eye is that which goes from the annulus through the phase plate. Whereas presence of organisms would diffract and scatter the light. The light passing through the fluid gets out of phase with the light that has the organisms stand out in contrast to their background. Equipment Needed An annulus, a phase plate and a telescope that is needed for adjusting the rings of both annulus and the phase plate. Method 1. Focus the specimen with the right objective after illuminating the microscope. 2. Place the matching annulus at its position. 3. Remove the eyepiece and put the telescope in its place, adjust it till the two rings, one bright and one dark are in focus. 4. Adjust condenser screws till the bright annulus ring fits exactly into the darker ring of the phase plate. 5. Remove the telescope, replace the eyepiece, focus and examine the specimen. Importance This

  Micro = Small, Scope = to view. It magnifies the image of the object to be visualized through it. Normally, the laboratory microscopes provide 18 Concise Book of Medical Laboratory Technology: Methods and Interpretations a magnification of 40x (scanner), 100x (low power), 400x (high power) and 1000x (oil immersion). The total magnification is obtained by multiplying the magnification of the objective with that of the eyepiece. Parts of the Microscope It has three sets of parts. They are the: 1. Stand, 2. Mechanical adjustments, and 3. Optics or the lenses. Stand It consists of: 1. The tube—supports objectives and eyepiece. 2. The body—gives support to the tube. 3. The arm—gives correct height and angulation to the body and the tube. 4. The stage with a pair of spring clips or a mechanical stage. 5. The substage holds the condenser lens with its iris diaphragm and a holder for light filters and stops. 6. The foot on which other parts rest, can be in tripod or horseshoe shape. Mechanic