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Biomedical subjects

J Gordon

Publications and source records attributed to J Gordon.

At least 361 records · Page 20Linked to original sources
PubMed1984

Depletions of central norepinephrine by intraventricular xylamine in rats.

A series of neurochemical studies evaluated the selectivity of the depletions of norepinephrine produced by intraventricular injections of xylamine. Brain monoamines were assayed by liquid chromatography with electrochemical detection. With ether anesthesia, bilateral injections of 50 or 100 micrograms xylamine reduced hippocampal levels of norepinephrine and serotonin without affecting striatal dopamine or serotonin. The depletion of hippocampal norepinephrine was significant as soon as 24 h. Animals treated with the combination of 20 mg/kg fluoxetine and 100 micrograms xylamine had selective depletions of central norepinephrine with no significant changes in serotonin.

Animals↗
PubMed1984

Ethylene oxide: an overview of toxicologic and epidemiologic research.

Ethylene oxide (EtO) is a reactive epoxide and potent biocide. It is used widely in gas sterilization of hospital equipment. An estimated 75,000 health care workers in the United States have potential exposure. EtO binds covalently to deoxyribonucleic acid (DNA) and has been shown in 13 species to cause point mutations. Apparently, as a consequence of its alkylating ability, EtO exposure can result in chromosomal damage. In monkeys EtO exposure produces increased frequencies of sister chromatid exchanges (SCEs) and chromosomal aberrations. In man, five cytogenetic studies have shown dose-related increased frequencies of either SCE or chromosomal aberrations; in one study SCEs developed after regular exposures lasting less than five minutes per day. EtO is a reproductive toxin. In adult male rats, exposure produces decreased fertility, increased fetal deaths, and heritable chromosomal translocations. In pregnant female rats and rabbits, exposure causes increased fetal losses, and in one study in pregnant mice exposure was associated with increased numbers of malformed fetuses. In male monkeys EtO causes dose-related reductions in sperm count and sperm motility. In pregnant women, one study suggests that brief occupational exposure twice daily in concentrations of 20 ppm or above was associated with increased spontaneous abortions. EtO is carcinogenic to animals. In rats it causes dose-related increases in mononuclear cell leukemias, peritoneal mesotheliomas, and cerebral gliomas. In man, exposure has been associated in two epidemiologic studies with increased leukemias: 3 leukemias observed versus 0.2 expected in one study, and 2 observed versus 0.14 expected in the other; two additional small studies of limited power found no excess leukemias. Quantitative risk assessment indicates that from 634 to 1,093 excess deaths from cancer will occur per 10,000 workers exposed to EtO at 50 ppm over a working lifetime, and that 12 to 23 excess cancer deaths will occur per 10,000 workers exposed at 1 ppm. The National Institute for Occupational Safety and Health (NIOSH) recommends that EtO be regarded as a potential human carcinogen. NIOSH has recommended that eight-hour time-weighted average exposure to EtO be less than 0.1 ppm and that short-term peak exposure not exceed 5 ppm for more than ten minutes per working day.

Abnormalities, Drug-Induced↗
PubMed1984

EMG patterns in antagonist muscles during isometric contraction in man: relations to response dynamics.

We studied the EMG activity of biceps and triceps in human subjects during isometric force adjustments at the elbow. Rapid targeted force pulses exhibited stereotyped trajectories in which peak force was a linear function of the derivatives of force and the time to peak force was largely independent of its amplitude. These responses were associated with an alternating triphasic pattern of EMG bursts in agonist and antagonist muscles similar to that previously described for rapid limb movements. When the instructions demanded rapid force pulses, initial agonist bursts were of constant duration, and their magnitude was strongly related to peak force achieved. The timing of EMG bursts in antagonist pairs was closely coupled to the dynamics of the force trajectory, and the rising phase of the force was determined by both agonist and antagonist bursts. When peak force was kept constant and rise time systematically varied, the presence and magnitude of antagonist and late agonist bursts were dependent on the rate of rise of force, appearing at a threshold value and then increasing in proportion to this parameter. It is proposed that antagonist activity compensates for nonlinearity in muscle properties to enable the linear scaling of targeted forces which characterizes performance in this task.

Adult↗
PubMed1984

Dysfunction of humoral immunity in anergic surgical patients: absence of anti-tetanus IgG antibody production.

The experiments described have shown that, whereas the injection of tetanus toxoid (tet) into 8 of 12 control individuals resulted in the appearance of specific anti-tet-IgG antibodies in their plasma, immunization of 14 anergic patients did not elicit an antibody response. This observation was extended to an in vitro system, where cells from four control subjects were shown to secrete anti-tet-IgG antibodies in response to polyclonal activators whereas cells from eight anergic patients did not. It is suggested that this failure of humoral immunity could account for the high risk of bacterial infections in anergy.

Adult↗
PubMed1984

Comparative effects of volatile anaesthetic agents and nitrous oxide on human leucocyte chemotaxis in vitro.

Infection following surgery is not uncommon. Human leucocytes play a vital role in the body's defense against infection. In order to decrease perioperative morbidity and mortality from infection, it is important to define the comparative effects of different anaesthetic agents on the leucocyte function. Therefore, the effect of equipotent concentrations (MAC 1) of isoflurane, enflurane, halothane, methoxyflurane and 70 per cent nitrous oxide, on the leucocyte chemotactic migration was investigated in vitro. The chemotactic migration of neutrophils and monocytes, with and without equilibration with MAC 1 concentrations of different volatile anaesthetics and 70 per cent nitrous oxide, was compared by using a modification of Boyden's method. Chemotactic migration of both cell types was unaffected by isoflurane, but a significant depression of chemotactic migration was observed with enflurane, halothane, methoxyflurane and nitrous oxide (p less than 0.05). The severity of depression of migration was maximal with nitrous oxide, followed by methoxyflurane, halothane and enflurane in order. It is concluded that equipotent concentrations of various anaesthetic agents produce different degrees of depression of leucocyte chemotactic migration in vitro.

Anesthesia, Inhalation↗
PubMed1984

Application of the dot immunobinding assay to allergy diagnosis.

The recently developed dot immunobinding assay is operationally simple and facilitates performance of multiple simultaneous assays. Here, its use as the basis for determination of total and allergen-specific IgE is established. For total IgE, the same commercially available polyclonal anti-human IgE was used on the solid phase and as a peroxidase conjugate in the liquid phase. After incubation with a chromogenic substrate, IgE was determined from the color intensity of the resulting dots with a scanning reflectance densitometer. The limit of sensitivity was 50 pg/ml of IgE. Standardized conditions gave the dynamic range 50 to 2500 IU/ml in serum. The IgE measured was not subject to interference by serum components, was labile at 56 degrees C, was soluble at 30% saturation (NH4)2SO4, and was unaffected by anti-human immunoglobulins of other specificity. Coefficients of variation were 0.05 within run, and were 0.1 between run. Comparison with data on sera obtained with the PRIST method yielded a correlation coefficient of 0.96 and a linear regression of slope 1.15. Assays for allergen-specific IgE were established with bee venom and dust mite allergens in the solid phase. The same peroxidase-conjugated antibody was used as for total IgE. Comparisons with comparable RAST assays were performed.

Antibody Specificity↗
PubMed1984

Nuclear magnetic resonance in schizophrenia: a preliminary study.

Nuclear magnetic resonance (NMR) scans were performed in nine patients with schizophrenia and five control subjects. NMR scans allowed multiple-plane views of the brains of schizophrenic patients and demonstrated much greater detail of morphological structure than computed tomographic (CT) scans. This small sample of subjects, however, showed no significant differences in several quantitative measurements between schizophrenic patients and control subjects. Problems in the interpretation of image intensity measures of NMR scans are discussed.

Adult↗
PubMed1984

Mechanisms of tumour cell escape encountered in treating lymphocytic leukaemia with anti-idiotypic antibody.

Four patients with chronic lymphocytic leukaemia were treated by one or more infusions of polyclonal antibody specific for the immunoglobulin idiotype expressed on their leukaemic cells. The antibody was in the form of IgG from sheep antiserum. Three of the 4 cases showed a significant fall in blood lymphocyte count. On one occasion most of the residual circulating lymphocytes were apparently dead. However on all occasions the cell counts rebounded to near pre-infusion levels within one week. Viable lymphocytes recovered from the blood after infusion always showed evidence of antigenic modulation: a diminished level of surface idiotype in a patched distribution, with an accompanying refractoriness to lysis by anti-idiotype plus complement. When cultured in vitro blood lymphocytes from three of the four patients revealed an appreciable export of idiotypic Ig. These 3 patients showed plasma levels of idiotypic Ig up to 400 micrograms ml-1, reduced by plasma exchange prior to infusion. The fourth patient had a level of less than 4 micrograms ml-1, and was the only one in whom free antibody could be found in the plasma after infusion. These cases demonstrate two major factors which thwart antibody attack on leukaemic cells--extracellular antigen and antigenic modulation--as well as problems relating to sparseness of surface antigen, recruitment of effectors, and exhaustion of effectors.

Aged↗
PubMed1984

In vivo and in vitro humoral immunity in surgical patients.

In vivo and in vitro humoral immunity was studied in surgical patients. Laboratory controls (LC), delayed type hypersensitivity (DTH) skin test reactive (HR), and anergic (HA) patients were immunized with tetanus toxoid. Maximum in vivo antibody levels occurred 14 days after immunization. Eighty-six, 47, and 17% of LC, HR, and HA subjects, respectively, showed a positive response (X2(2) = 21.1 with Yates, p less than 0.0005). Peak in vitro antibody production in unstimulated lymphocyte cultures occurred at day 6 after immunization. Antibody responses in vitro were reduced in all surgical patients, worst in HA, and correlated quantitatively with in vivo antibody responses at day 14 (Spearman rank correlation = 0.794, p less than 0.001). Total IgG production in vitro was not decreased; 595, 1080, and 1538 ng IgG/culture were produced by LC, HR, and HA, respectively. These data demonstrate decreased in vivo and in vitro humoral immunity in all surgical patients, worst in those with decreased DTH responses. There is a kinetic and quantitative correlation between in vivo and in vitro responses, the latter being a biologic reflection of the integrity and magnitude of the in vivo process. Finally, failure to produce specific antibody is not due to failure of total IgG synthesis.

Antibodies, Bacterial↗
PubMed1984

An investigation of the attitudes of medical students to physically disabled people.

A study was carried out to investigate the change in attitudes towards physically disabled people of a group of fifty-eight medical students during the first 3 years of their course. The students attended a newly established medical school which has developed a curriculum without the traditional division into preclinical and clinical years and where contact with patients occurs from the first year. Results demonstrated that, as expected, at the start of the course the attitudes of females towards disabled people were more positive than those of males. Also, a significant change in attitudes was found after 3 years, both males and females demonstrating more positive attitudes toward physical disability. The differences between males and females were maintained. The relationship between these students' attitudes and their behaviour was discussed and proposals for further research to investigate this are outlined.

Attitude of Health Personnel↗
PubMed1984

Reach out!

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Hospital Bed Capacity, 300 to 499↗
PubMed1984

Anti-immunoglobulin inhibits DNA synthesis in Epstein-Barr virus-transformed lymphoblastoid cell lines.

Antibodies directed against immunoglobulin (anti-Ig) were found to inhibit the spontaneous incorporation of [3H]thymidine by Epstein-Barr virus (EBV) transformed lymphoblastoid cell lines (LCL). The degree of inhibition was variable but could exceed 80% following a 24 hr exposure of cells to anti-Ig. While a short pulse of antibody was sufficient to cause inhibition, maintainance of the effect required the continual presence of anti-Ig in culture. Maximal suppression by anti-Ig of [3H]thymidine uptake was reached between days 3 and 5, but cells eventually escaped from inhibition. For a line coexpressing IgM and IgD at the cell surfaces it was found that antibodies specific for the individual isotypes were equally effective at inducing suppression. Successful inhibition of DNA synthesis by F(ab')2 fragments of anti-Ig demonstrated that the Fc portion was not required for this effect. Anti-Ig immobilized on plastic surfaces was as effective as soluble antibody in inducing suppression. The implications of these findings for the generation of EBV-transformed LCL producing specific antibody are discussed.

Antibodies, Anti-Idiotypic↗