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First used as an animal model of poliomyelitis in the late 1940s, the cotton rat is currently used in biomedical research for studies of human respiratory syncytial virus and filariasis. The author provides useful information relevant to the care of these research animals, including husbandry considerations, proper handling, and common laboratory procedures.
This is intended to be a practical review for the clinical chemist of the laboratory procedures most commonly used to quantitate hormone receptors in various cellular fractions. These procedures include use of charcoal adsorption and hydroxylapatite for intracellular receptors and of centrifugation and filtration for membrane receptors. We discuss the use of the Scatchard analysis to establish the steroid-receptor affinity and the quantity of steroid-receptor binding sites. Both pre- and post-labeled sucrose density gradient methods are outlined. One section is devoted to the direct and indirect methods used in nuclear "exchange" assays. Basic theory underlying each assay is presented, but, more importantly, we assess the advantages and disadvantages of each procedure. On the basis of this information, one may decide which assay is best suited for a particular laboratory and (or) specimen.
With the use of a positional index, the restorative dentist and laboratory technician can be provided with an accurate record of implant fixture location after first-stage surgery. Thus it is possible to fabricate a master cast with implant analogs and initiate laboratory procedures immediately after first-stage surgery, and a provisional restoration can be processed and delivered at the time of second-stage surgery. A case report is presented to illustrate the technique.
Five types of hazards encountered in the clinical laboratory and a list of safety procedures designed to avoid or minimize them are identified. The safety procedures are written in a precise and easy-to-follow manner so that they can be adopted and used in any clinical laboratory. Medical technology educators are encouraged to teach safety procedures and enforce them in the student laboratory.
This paper reviews the various laboratory procedures available for the isolation and identification of Clostridium difficile and the detection of toxins produced by this organism. Laboratories should be selective in determining which patients require investigation for Clostridium difficile-associated diarrhoea. Transport and storage of stool specimens at 4 degrees C is recommended when delays in processing may occur. Tissue culture techniques are still the best method for detection of cytotoxin and a variety of cell lines can be used. Other methods for detecting cytotoxin, and methods for detecting other toxins are not sufficiently developed yet to warrant introduction into diagnostic laboratories. Culture techniques remain the most sensitive for diagnosis, particularly since the development of a variety of enrichment techniques. Cycloserine cefoxitin fructose agar is still adequate, although reduced concentrations of antimicrobial agents are necessary, and improvements, such as the addition of sodium taurocholate, increase the recovery of spores. Enrichment cultures have markedly increased isolation rates for Clostridium difficile but the significance of these isolates needs to be carefully evaluated. Until simpler and more reliable tests are available in clinical laboratories for the detection of toxins, the isolation of Clostridium difficile from patients with diarrhoeal disease should be considered paramount.
A procedure to reinforce mandibular complete dentures with a rigid internal horseshoe-shaped frame is described. Sequential clinical and laboratory procedures to incorporate a metal frame at a predetermined, controlled position within the prosthesis are presented. This procedure provides not only strength but ensures adequate space for a resilient liner if required.
The diagnosis of tuberculosis is an increasingly important problem confronting the clinical microbiology laboratory as well as hospital epidemiologists. The inherent delays in conventional laboratory procedures for the isolation and susceptibility testing of M tuberculosis may contribute directly to the spread of tuberculosis. Application of newer methods that are more rapid is essential if the spread of tuberculosis is to be limited. Hospital epidemiologists and clinical microbiology laboratories should work together to critically examine all of their current procedures for tuberculosis and take steps to correct or improve all omissions and delays in mycobacterial tests ordering, collection, testing, and reporting.
The results of the external quality assessment for clinical microbiology in Norway in 1984 are evaluated. Four distributions, each consisting of four simulated clinical specimens, were carried out. The assessment has, as in previous years, revealed some problem areas concerning laboratory procedures which are discussed.
Procedures for the fabrication of complete cast and ceramometal restorations that support existing removable partial dentures are reviewed. Clinical and laboratory procedures are presented. These techniques allow the patient to continue to function with the existing removable partial denture while the restorations are made.
OBJECTIVE: To document the occurrence and incidence of spontaneously occurring cataracts in older New Zealand White (NZW) and New Zealand White x New Zealand Red (NZW x NZR - F1) rabbits during prescreening examinations at Alcon Laboratories. PROCEDURES: A retrospective study was conducted on prescreening examination records of NZW and NZW x NZR (F1) rabbits at Alcon Laboratories between April 1999 and May 2001. RESULTS: A total of 946 rabbits (670 NZW and 276 NZW x NZR) ranging in age from 77 to 288 days were examined. Of the NZW rabbits, 333 were males and 337 were females. Of the NZW x NZR (F1) rabbits, 139 were males and 137 were females. Thirty-eight NZW rabbits (23 males and 15 females) exhibited immature cataracts in one or both eyes, and three NZW x NZR (F1) rabbits (one male and two females) exhibited cataracts in one or both eyes. The overall incidence of cataracts was 4.3% of all rabbits. Males and females were equally affected, but a significant difference in the incidence of cataracts existed between the NZW and NZW x NZR (F1) rabbits with 5.7% of the NZW rabbits affected and 1.1% of the NZW x NZR (F1) rabbits affected. CONCLUSION: Spontaneous juvenile cataracts occur in rabbits and may develop as incidental lesions during toxicologic studies. The incidence of cataracts noted in our studies is consistent with an autosomal recessive mode of inheritance, but further studies are needed to confirm the mode or modes of inheritance. Hybrid pigmented rabbits (F1 or NZW x NZR) exhibited a significantly lower incidence of cataracts.
Immune electron microscopic procedures for the detection of adenovirus type 7 directly in throat swab specimens from patients are described. Nineteen of 25 throat swab samples, known to be positive for adenovirus type 7 by isolation of virus from tissue culture, were shown to contain aggregates of adenovirions coated with antibody. Sensitivity tests of the immune electron microscopic method showed that as few as 16 to 32 tissue culture infective doses of virus could be detected by the direct immune electron microscopic technique. It was also demonstrated that aggregation of virus-antibody complexes could be further enhanced by use of anti-immunoglobulin G sera (indirect immune electron microscopic procedures). These results demonstrate that examination of patient specimen by immune electron microscopic procedures is a feasible and rapid method for adenovirus detection and suggest that it could be applied as a routine laboratory procedure for the diagnosis of other virus infections.
The diagnosis of bacterial meningitis rests on examination of the CSF. The gross appearance of the fluid may be cloudy or turbid if the white cell count is elevated. Gram's staining should always be used in examining CSF, as it permits rapid and accurate identification of the etiologic agent in approximately 60 to 90 percent of cases of bacterial meningitis. The CSF culture is positive in approximately 70 to 85 percent of patients with bacterial meningitis. Many other rapid diagnostic tests have been developed to aid in the diagnosis of bacterial meningitis when Gram's staining gives negative results. Nevertheless, newer techniques are more rapid and sensitive, postgraduate training in laboratory medicine should include basic clinical skills (Communication skills, physical examination and common laboratory procedures such as Gram's stain, Wright-Giemsa stain, etc.) and 24 hours on-call service system by laboratory physicians. It must not be focused solely on the sophistication of laboratory methods. We must notice that an increasing gap between the clinic and the laboratory. Current needs require us to make a major attempt to bridge this gap. We, laboratory physicians must modify our behavior effectively and accept the value and limitations of laboratory automation and information technology. We must work more closely with physicians and other health care professionals to establish a good collaborative partnership with them.
A study was carried out to compare the efficiency of the Microstix-Candida system with the standard method of isolating candida using Sabouraud medium. It was found that the Microstix-Candida system gave a 96.8% correlation with the standard method for vaginal specimens, and 91.8% correlation for other specimens. The Microstix-Candida system may be a useful laboratory procedure, in addition to direct microscopy, for the diagnosis and management of vaginal candidiasis in clinics with limited access to laboratory facilities.
There are no current U.K. or international guidelines or regulations covering the production, processing and storage of haemopoietic cells such as to allow their engraftment following myeloablative therapy. This paper seeks to provide such guidelines. It enumerates how quality control and assurance can be applied to this area of transfusion medicine; procedural steps relating to bone marrow harvest on peripheral blood stem cell collection are outlined and recommended doses of nucleated cells suggested for both procedures. General specifications for identification, storage and transportation of bone marrow and peripheral blood stem cells are included and specific laboratory procedures related to the provision of haemopoietic cells for engraftment are outlined. Umbilical cord blood transplants and long-term bone marrow culture are alluded to but these are still in a research phase.
Routine preoperative tests such as the determination of bleeding time and coagulation time are unnecessary and are not recommended. Rulings which require routine preoperative tests result in the adoption of inferior and unreliable time-saving methods in the laboratory. If the clinical staff insists that laboratory procedures to predict hemorrhage be performed on every patient scheduled for operation, approved methods of performing the tests should be employed. Preoperative procedures should include a personal and a family history, a careful and complete physical examination and screening laboratory tests such as urinalysis, hematocrit, leukocyte count and smear examination, including estimation of the number of thrombocytes. Special hemorrhagic studies are indicated on selected patients. These selected patients include those who have a history of abnormal bleeding, those who consider themselves "easy bleeders" or who have apprehension concerning hemorrhage at the time of operation, and those who have physical signs of hemorrhage. Special hemorrhagic studies should also be performed on patients who have diseases that are known to be associated with vascular and coagulation abnormalities, infants who have not been subjected to tests of trauma and on patients from whom a reliable history cannot be obtained. Extra precaution should be taken if operation is to be performed in hospitals or clinics that do not have adequate blood banking facilities and if the operation to be performed is one in which difficulty in hemostasis is anticipated. THE PREOPERATIVE TESTS THAT ARE INDICATED ON SELECTED PATIENTS SHOULD INCLUDE AS A MINIMUM: The thrombocyte count, determination of the bleeding time by the Ivy method, determination of the coagulation time by the multiple tube method and the observation of the clot. Where facilities are available, the hemorrhagic study should also include the plasma and serum prothrombin activity tests.
UNLABELLED: In a pharmacist-managed anticoagulation clinic, portable point-of-care coagulation devices may facilitate patient monitoring by providing rapid INR measurement. Few studies, however, have validated this type of device. OBJECTIVE: To evaluate the reliability, validity and ease of use of the CoaguChek S, a new portable coagulation device. METHODS: A total of 100 patients followed at a pharmacist-managed anticoagulation clinic attended two study visits. INRs were measured using the CoaguChek S and the standard laboratory technique. RESULTS: Reliability: The test-retest reliability (precision) of the CoaguChek S, estimated by the intraclass correlation coefficient (ICC) and a 95% confidence interval (95% CI), was high (0.98 (0.98-0.99)) and comparable to the standard laboratory technique (0.99 (0.98-0.99)). Interrater reliability was also high (0.97 (0.95-0.98)). Reliability coefficients did not vary with the test-strip lot number nor the CoaguChek S operator. VALIDITY: When compared with standard laboratory procedure, the ICC (95% CI) was equal to 0.93 (0.91-0.95). The mean difference (95% CI) between INR measured by the laboratory and the CoaguChek S was equal to -0.02 units (-0.06-0.03). The mean absolute and relative absolute differences (95% CI) were equal to 0.24 units (0.21-0.27) and 9% (8%-10%), respectively. Differences tended to increase for INRs greater than 3 units as seen by a mean difference (95% CI) of -0.17 units (-0.35-0.02). This represented a mean absolute difference (95% CI) of 0.44 units (0.33-0.55) and a mean relative absolute difference of 12% (9%-15%). Concordance between therapeutic decisions based on CoaguChek S and laboratory results was high (Kappa = 0.68). In 34 cases (18%), the therapeutic decision would have been different. However, in 15 of these discordant observations, the difference between the CoaguCheck S and laboratory INR was <or=0.25 units. Ease of use: In 3% of cases, no INR could be measured by the CoaguChek S. The percentage of extra finger pricks and extra test-strips were equal to 25.8% and 23.7%, respectively. CONCLUSIONS: When used by health professionals in a pharmacist-managed anticoagulation clinic, the CoaguChek S is reliable, valid and easy to use. However, its validity tends to decrease as the INR increases, possibly due to the low sensitivity of the thromboplastin. If the CoaguChek S INR is supratherapeutic, we would therefore recommend confirming the results with a standard laboratory measurement.
The accuracy of commercially prepackaged kits for microbial identification has become well established. Laboratory workers may encounter increasing demands for production of objective data to justify replacement of systems using individual biochemical tests in tubes. The authors present a system of cost analysis in which materials and labor costs are separately computed, and to which are added the effects of (1) fringe benefits, (2) decreased productivity resulting from administration, quality control, education and development, and (3) the additional expense of indirect costs that are allocated to laboratory procedures by accepted and standardized hospital accounting methods. Labor costs should be based on time-engineered studies conducted in individual laboratories. Alternatively, various published "unit values" may be used. The result may present several alternative differences in cost, depending on which unit values are accepted as applicable to the individual laboratory. Despite these uncertainties, the method of analysis provides a more objective means of justifying the cost of introduction of prepackaged kits where accuracy and speed of identification have already been proven to have advantages over biochemical tests in tubes.
A course has been devised to simulate a hospital stat lab environment for students in a 2-year MLT Associate Degree program. This course ensures that each student will individually perform a wide variety of laboratory procedures and report results under hospital-like circumstances. This course, which has received favorable comment from NAACLS, circumvents problems of insufficient placement situations, inadequate supervision, and limited variety of student experience in hospital sites. Course procedures, objectives, and student evaluation methods are described.