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Biomedical subjects

M Clark

Publications and source records attributed to M Clark.

At least 289 records · Page 16Linked to original sources
PubMed1984

Immunohistological screening in the selection of monoclonal antibodies: the use of isotype-specific antiglobulins.

This paper describes the use of the immunoperoxidase technique for the screening of rat hybridoma culture supernatants on tissue sections. By combining the avidin-biotin system with mouse monoclonal antibodies specific to different rat immunoglobulin isotypes, it is possible to resolve the specificity patterns of complex mixtures of monoclonal antibodies from uncloned culture wells. This strategy is particularly useful in the derivation of monoclonal antibodies to cell surface antigens.

Animals↗
PubMed1984

The prevalence of hepatitis B serological markers in emergency physicians.

Hepatitis B (HBV) is a well-documented, increasing occupational hazard to those in the medical and dental professions. While the prevalence of markers of hepatitis B in the general population in the United States is approximately 3% to 5%, the prevalence in the health professions has been found to be higher. The prevalence of markers in 260 emergency physicians, consisting of teaching and nonteaching staff and emergency medicine residents, was the focus of this study. Two hundred fourteen participants had not received hepatitis B vaccine; 46 had received the vaccine. Hepatitis B surface antigen (HBsAg), surface antibody (anti-HBs) and core antibody (anti-HBc) were tested. The overall prevalence of markers in the nonvaccinated group was 11.7% (25/214). Forty-one of 46 participants (89%) who had received hepatitis B vaccine demonstrated anti-HBs, evidence of immunity to hepatitis B. Thirty-nine of them had anti-HBs alone, and two had anti-HBs and anti-HBc. Of the five vaccinees who failed to demonstrate anti-HBs, one demonstrated anti-HBc alone. There was no statistically significant difference between the three groups in prevalence or type of markers. The prevalence of hepatitis B serological markers in this survey of emergency physicians was two and a half to four times that of the general population. Because of the increased risk of exposure to hepatitis B virus, early immunization against this disease through the use of hepatitis B vaccine should be considered by physicians in the practice of emergency medicine.

Emergency Medicine↗
PubMed1984

Ventricular tachyarrhythmias in the long QT syndromes.

Marked prolongation of the electrocardiographic QT interval often is associated with a distinctive form of ventricular tachycardia characterized by the gradual oscillation around the baseline of the peaks of successive QRS complexes. This was named torsades de pointes, or "twisting of the points." This form of ventricular tachycardia tends to be rapid and self-terminating and often occurs in clusters, leading afflicted patients to present with recurrent dizziness and syncope. Ventricular fibrillation and sudden death are common.

Adrenergic beta-Agonists↗
PubMed1984

Constant ventricular drainage: pitfalls and variables. Technical note.

After observing the erratic performance of a commercially available ventricular drainage system, we examined the hydrostatic pressure exerted by the system as a function of the volume of fluid within the drainage bag (at a constant height). Initially, 3 to 4 cm more than the expected 27 cm of height was required to achieve a drainage pressure of 20 mm Hg. As the volume of fluid increased, there was an initial precipitous fall from the 20 mm Hg preset pressure to 14 to 16 mm Hg; this pressure differential increased as the volume of drained fluid increased. Removal of air from the drainage bag resulted in an additional decrement in the observed hydrostatic pressure. These decrements in pressure were not apparent with another commercially available bag used commonly for ventricular drainage. We therefore recommend that, if ventricular drainage is to be accomplished against a constant hydrostatic pressure head, the system should be configured so that the actual hydrostatic pressure against which drainage occurs can be measured quickly and easily. The system should be checked at frequent intervals as the ventricular drainage bag fills. We note additional pitfalls in use of constant ventricular drainage and suggest solutions.

Cerebral Ventricles↗
PubMed1984

EEG time and frequency domain measures of cerebral specialization.

Electroencephalographic (EEG) studies of lateralized cognitive functions have primarily relied upon measures of averaged evoked potentials (AEP) and power spectra (PS) to demonstrate hemispheric differences. The nature of the tasks appropriate to each of these methods of signal analysis generally require different cognitive activities and suggest different assumptions about cerebral specialization. This study investigated whether the tasks associated with either method were more likely to produce EEG asymmetries. Eighteen right-handed subjects participated in a three phase experiment which varied the amount of subject involvement in task performance. Phase I entailed passive listening to speech and nonspeech sounds. Phase II required active attention to speech and nonspeech sounds. Phase III involved a verbal matching task, a spatial rotations task, and a noncognitive control task. Auditory AEPs were measured in Phases I and II, and PS were measured in Phase II and III. EEG recordings were obtained from frontal and parietal areas of both hemispheres (F3, F4, P3, P4) referred to linked ears. Power spectra were derived from the 4-8, 8-13, and 13-20 Hz frequency bands at each lead. Despite statistically significant task and/or stimuli differences found in all three phases of study, essentially no task by lead interactions were obtained. That is, interhemispheric activity did not covary with differing stimuli and tasks. The absence of such interactions calls into question uncritical acceptance of a simple direct relation between task performance, EEG activity, and hemisphere specialization.

Acoustic Stimulation↗
PubMed1983

CT diagnosis of tracheobronchopathia osteochondroplastica.

Computed tomography (CT) demonstrated nodular thickening with calcification in the anterior and lateral tracheal walls of a patient with tracheobronchopathia osteochondroplastica. The CT findings in this rare disease are pathognomonic.

Aged↗
PubMed1983

A hemodialysis orientation unit.

A separate dialysis unit was created within an existing large dialysis unit for the purpose of segregating all new hemodialysis patients into an environment that would provide optimum instruction about self-care. An educational curriculum was presented to each patient during each dialysis over the first 2 months of dialysis. Depending upon medical condition and response to the curriculum, patients were transferred either to the home hemodialysis training unit with or without a helper, to the limited care facility, or to the general dialysis area for medically unstable patients. An orientation unit not only improves patient participation in self-care, but appears to increase the number of patients interested in dialyzing at home.

Adolescent↗
PubMed1983

Separation of hemopoietic cells from adult mouse marrow by use of monoclonal antibodies.

Primitive hemopoietic progenitor cells from adult mouse marrow have been substantially enriched by virtue of a negative selection procedure with monoclonal antibodies. It has been possible to segregate erythroid progenitor cells at distinct stages of differentiation on the basis of their cell surface antigens. This has been achieved with two monoclonal antibodies reactive with the mature elements of bone marrow. YBM 34.3 binds to a heat-stable antigen expressed on B lymphocytes, neutrophils, and cells of the erythroid lineage. YBM 6.1 reacts with cells of the neutrophil, eosinophil, and monocyte series but does not bind to colony-forming cells. Separation is achieved by indirect immunoadsorption (panning) with YBM 34.3 on Protein-A-coated plastic plates followed by FACS II cell sorting with YBM 6.1. The combined procedures yield a marrow population containing 58% immature cells (blasts, promyelocytes, and myelocytes) and 9.5% clonogenic cells. In addition, differential binding of YBM 34.3 can be used to segregate erythroid progenitor cells at distinct stages of differentiation (day 7 BFU-E, day 5 BFU-E and CFU-E) either by cell sorting or panning. It is shown that both techniques give a comparable degree of resolution of the different cell types with, however, an appreciable advantage of panning over cell sorting in allowing the rapid handling of large numbers of cells.

Animals↗