Biomedical subjects
P M Fischer
Publications and source records attributed to P M Fischer.
Elementary school students' performance with two ELISA test systems.
OBJECTIVE: To examine analytic performance by previously untrained and inexperienced subjects using enzyme-linked immunosorbent assay (ELISA) tests developed for decentralized laboratories. Performance variability between tests assigned to the "simple" and "moderately complex" Health Care Financing Administration laboratory levels was evaluated. DESIGN: A nonrandomized trial of the Surecell Strep-A chorionic gonadotropin ELISA tests. Each subject processed nine unknown specimens (three negative, three weakly positive, and three strongly positive) for each ELISA test. Subjects were blinded to expected test results. SETTING: An elementary school. SUBJECTS: A convenience sample of 52 students enrolled in the sixth and seventh grades. This age group was chosen because of their ability to generally comprehend instructions and remain attentive to the testing task. INTERVENTIONS: Subjects were either self-trained by reading package insert directions or trained by a manufacturer's sales representative. MAIN OUTCOME MEASURES: Performance was measured as the percentage of correct test results for the unknown specimens. The sensitivity and specificity for each test by operator group were calculated. RESULTS: Subjects demonstrated an overall sensitivity of 97.1% and specificity of 94.7% for human chorionic gonadotropin unknown specimens and a 95.9% sensitivity and 96.8% specificity for group A streptococcus unknown specimens. No significant differences between the self-trained group and the representative-trained group were observed for either group A streptococcus or human chorionic gonadotropin tests. Performance was so high with the first specimen that improvement over time (ie, a "learning curve") could not be demonstrated. CONCLUSION: These ELISA test systems are able to achieve high levels of performance by subjects with no formal laboratory background, no previous method specific experience, and limited self-training.
Application of arylsulphonyl side-chain protected arginines in solid-phase peptide synthesis based on 9-fluorenylmethoxycarbonyl amino protecting strategy.
One of the main problems still hampering solid-phase peptide synthesis using orthogonal protection strategies based on the 9-fluorenylmethoxycarbonyl amino protecting group is the difficult removal of currently used arginine arylsulphonyl guanidino protecting groups. Poor acid liability of 4-methoxy-2,3,6-trimethylbenzenesulphonyl-protected arginine has led to the popularity of the newer 2,2,5,7,8- pentamethylchroman-6-sulphonyl guanidino protecting group. This group was initially believed to have liability to trifluoroacetic acid, the reagent commonly used to simultaneously deprotect peptides and detach them from the synthesis resin, comparable to tert.-butyl and trityl type protecting groups used for the protection of other peptide side-chain functionalities. In a comparison of three established cleavage/deprotection mixtures we have shown that this is not always the case, particularly in multiple arginine peptides. We have found that only hard-acid deprotection with trimethylsilyl bromide reliably removed both arylsulphonyl guanidino protecting groups from a variety of arginine-containing peptides.
Culture and antigen detection tests for streptococcal tonsillopharyngitis.
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Beyond the state of the Journal.
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Hospital efforts in smoking control: remaining barriers and challenges.
BACKGROUND: This study reports the barriers and challenges for hospital tobacco control efforts after the institution of smoke-free policies. METHODS: Surveys of employees and inpatients of five hospitals in Augusta, Georgia, were conducted and evaluated 4 months after joint hospital implementation of smoke-free policies. A random sample of 1997 employees and a convenience sample of 517 inpatients returned usable surveys. RESULTS: Although attitudes to the hospital bans on smoking reflected strong support for smoke-free policies, four out of five hospitals reported significant implementation problems. Despite the bans, 49% of patients who were smokers continued to smoke while hospitalized, and almost one half of all hospitalized smokers had received no advice to quit smoking from a physician or a nurse since admission. Employees and patients both agreed that the smoke-free policies had benefited employees more than patients. CONCLUSIONS: Despite achieving a smoke-free status, there are many challenges that remain for comprehensive hospital tobacco-control efforts. Hospitals and health care professionals must remain particularly alert and attentive to the needs of patients and employees still addicted to tobacco.
Brand logo recognition by children aged 3 to 6 years. Mickey Mouse and Old Joe the Camel.
OBJECTIVE: Little is known about the influence of advertising on very young children. We, therefore, measured product logo recognition by subjects aged 3 to 6 years. DESIGN: Children were instructed to match logos with one of 12 products pictured on a game board. Twenty-two logos were tested, including those representing children's products, adult products, and those for two popular cigarette brands (Camel and Marlboro). SETTING: Preschools in Augusta and Atlanta, Ga. PARTICIPANTS: A convenience sample of 229 children attending preschool. RESULTS: The children demonstrated high rates of logo recognition. When analyzed by product category, the level of recognition of cigarette logos was intermediate between children's and adult products. The recognition rates of The Disney Channel logo and Old Joe (the cartoon character promoting Camel cigarettes) were highest in their respective product categories. Recognition rates increased with age. Approximately 30% of 3-year-old children correctly matched Old Joe with a picture of a cigarette compared with 91.3% of 6-year-old children. CONCLUSION: Very young children see, understand, and remember advertising. Given the serious health consequences of smoking, the exposure of children to environmental tobacco advertising may represent an important health risk and should be studied further.
Tobacco coupons and teenagers.
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Solid-phase peptide synthesis without side-chain hydroxyl protection of threonine.
A peptide containing four threonine residues was synthesised by the solid-phase method using fluorenyl-methoxycarbonylamino acid reactive esters or coupling by preactivation with 1-hydroxybenzotriazole and Castro's reagent. In two separate experiments the synthesis was carried out with or without protection of the side-chain hydroxyl group of threonine as the tert.-butyl ether. Comparison of the crude peptides after deprotection and detachment from the synthesis resin suggests that side-chain protection of threonine is unnecessary under the synthetic conditions employed.
Noninvasive detection of Chlamydia trachomatis urethritis in men by a rapid enzyme immunoassay test.
BACKGROUND: The purpose of this investigation was to evaluate the ability of a rapid enzyme immunoassay test to noninvasively detect Chlamydia trachomatis urethritis in men from a urine specimen. METHODS: Urethral samples and urine from 207 patients were evaluated. Urethral and urine sediment Gram stains, leukocyte esterase dipstick tests, and enzyme immunoassay analyses of centrifuged and uncentrifuged urine were compared with urethral C trachomatis culture. RESULTS: The prevalence of infection in this population was 10.3%. Sensitivity and specificity of the enzyme immunoassay on the centrifuged urine specimen were 70% and 96%, respectively. The positive and negative predictive values were 67% and 97%, respectively. The uncentrifuged urine enzyme immunoassay sensitivity was 35.7% and specificity was 98.9%. Leukocyte esterase test sensitivity compared with that of the Neisseria gonorrhoeae and/or C trachomatis cultures was 83.3%, and specificity was 52%. CONCLUSIONS: The rapid enzyme immunoassay clinically complemented the screening urine sediment Gram stain and the leukocyte esterase test. The judicious use of a noninvasive C trachomatis rapid enzyme immunoassay test to identify organism-specific urethritis may improve patient management of sexually transmitted disease.
An evaluation of a whole blood prothrombin analyzer designed for use by individuals without formal laboratory training.
BACKGROUND: The prothrombin time (PT) test, which is the most common coagulation test used in the outpatient setting, has not been recommended for office laboratory use because it has been technically difficult to perform. Consequently, serious errors in patient care could occur because of an erroneous result. The Coumatrak (E.I. Du Pont, Wilmington, Del) now allows nontechnically trained office staff to perform PT tests using a fresh capillary whole blood sample, individually packaged reagent cartridges, and a portable battery-operated instrument. METHODS: Coumatrak PT testing was compared with standard methods for both precision and accuracy, using protocols developed by the National Committee for Clinical Laboratory Standards (NCCLS). Reagent stability and operator variability were also studied. RESULTS: The results produced by a trained technologist and nontechnically trained staff were comparable. Test results obtained with the Coumatrak were approximately 10% higher than results obtained using standard laboratory equipment and methods using comparable blood samples from the same patients. It was found that the capillary blood specimen had to be rapidly transferred to the reagent cartridge in order to avoid factitiously low results. CONCLUSIONS: The Coumatrak can rapidly provide PT test results that are clinically useful for the office management of patients being treated with a warfarin anticoagulant and for the diagnosis of selected disorders. The system was found to be easy to operate, appropriate for use by individuals with little laboratory experience, and was subject to few operational problems during this study.
Laboratory testing in the 1990s.
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Evolution of a specialty journal.
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Direct enzyme-linked immunosorbent assay of anti-peptide antibodies using capture of biotinylated peptides by immobilized avidin.
Synthetic peptides were prepared by a solid-phase method and biotinylated selectively and in high yield at the amino terminus prior to peptide deprotection and detachment from synthesis resin. It was shown that peptides biotinylated in this manner could be bound by avidin immobilized on a plastic surface and used to detect anti-peptide antibodies in an enzyme-linked immunosorbent assay. The advantages of this method compared to conventional immunoassay techniques for anti-peptide antibodies are discussed.
Impact of a public cholesterol screening program.
The National Cholesterol Education Program (NCEP) has endorsed physician case finding as the primary method to detect individuals with elevated cholesterol levels. Despite this recommendation, promotional and for-profit public screening programs have flourished. We surveyed participants of a mall-based cholesterol screening program 1 year after their screening. Sixty-four percent of those screened had not previously known their cholesterol levels. Those who were newly screened were less likely to benefit from this testing than the general public, since they were older (mean age, 55.3 years), more likely to be female (67.4%), and nonsmokers (88%). Screenees had excellent recall of their cholesterol level (mean absolute reporting error, 0.24 mmol/L [9 mg/dL]) and a good understanding of cholesterol as a coronary heart disease risk. Those with elevated cholesterol levels reported high distress from screening but no reduction in overall psychosocial well-being and an actual decrease in absenteeism. Only 53.7% of all who were advised to seek follow-up because of an elevated screening value had done so within the year following the screening program. However, of those with values greater than 6.2 mmol/L (240 mg/dL), 68% had sought follow-up. Many of those who participate in public screening programs have been previously tested, fall into low-benefit groups, or fail to comply with recommended follow-up. We therefore conclude that cholesterol screening programs of the type now commonly offered are unlikely to contribute greatly to the national efforts to further reduce coronary heart disease.
A comparison of rapid enzyme immunoassay tests for the detection of Chlamydia trachomatis cervical infections.
Two rapid enzyme immunoassay test kits were compared with culture for the detection of Chlamydia trachomatis endocervical infections. Endocervical samples for C trachomatis culture and the two enzyme immunoassay tests were evaluated from 502 county health department and Planned Parenthood patients. The prevalence of infection in this population was 12%. Sensitivity and specificity of the Abbott TestPack Chlamydia were 51.7% and 99.5%, respectively, and of the Kodak Surecell Chlamydia were 76.7% and 98.6%, respectively. The positive and negative predictive values for TestPack were 93.9% and 93.8%, and for Surecell were 88.5% and 96.9%, respectively. Additionally, an in vitro investigation was used to evaluate whether typical office staff (physicians, nurses, medical technicians, receptionists, and radiology technicians) were able to perform competently the tests in each kit. Office personnel tested 12 dilutions of a C trachomatis stock sample or negative control sample as unknowns for each kit in the in vitro investigation. There were no differences among office staff in performance when compared for each test kit. Selective use of these enzyme immunoassay tests for high-risk patients in a family practice population that has a high prevalence of patients with C trachomatis infection may be helpful when rapid test results are required and cultures are not feasible. After appropriate training, most physician office personnel were equally able to perform the enzyme immunoassay tests evaluated.
Direct immunization with synthetic peptidyl-polyamide resin. Comparison with antibody production from free peptide and conjugates with carrier proteins.
An 11-amino acid residue peptidyl-linkage agent-polyamide resin complex was synthesized by the fluorenylmethyloxycarbonyl (Fmoc)-polyamide solid-phase system. Mice were immunized with the free peptide, peptidyl-resin and peptide coupled to the carrier proteins ovalbumin (Ova) and keyhole limpet haemocyanin (KLH). The immunogenicity of these materials was assessed by measurement of the capacity of the various antisera to bind the peptide in an enzyme-linked immunosorbent assay (ELISA). The peptidyl-resin exhibited enhanced immunogenicity compared to the free peptide. It is suggested that the time needed for screening for immunogenicity of large numbers of synthetic peptides thus be greatly shortened by using peptidyl-resins for immunization. This method eliminates laborious cleavage of peptide from resin, purification, coupling to carrier and the difficulties of handling peptides of low solubility.
Analysis of 4-N,N-dimethylaminoazobenzene 4'-thiohydantoin amino acids at sub-picomole levels by high-performance liquid chromatography: simultaneous manual sequencing of picomole quantities of several polypeptides.
A single-column high-performance liquid chromatographic separation of 4-N,N-dimethylaminoazobenzene 4'-thiohydantoin amino acid derivatives, generated during polypeptide sequence analysis by the 4-N,N-dimethylaminoazobenzene 4'-isothiocyanate/phenylisothiocyanate double coupling technique, is described. Recovery of the serine and threonine derivatives was improved by substituting boron trifluoride-diethyl etherate for trifluoroacetic acid in the thiazolinone cleavage reactions. Residues, including the S-carboxymethyl derivative of cysteine, were assigned after a single injection and a cycle time of 30 min. Quantities of 4-N,N-dimethylaminoazobenzene 4'-thiohydantoin amino acid derivatives as low as 100 fmol were detected. Interference of sequencing artefacts with residue assignment was avoided. This technique allows simultaneous manual sequencing of several proteins or peptides at the level of a few picomoles.