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Biomedical subjects

D McBride

Publications and source records attributed to D McBride.

At least 73 records · Page 4Linked to original sources
PubMed1986

Fatal xylenol self-poisoning.

A case of fatal xylenol ingestion by a long-stay mental hospital patient is described. The clinical course was similar to that observed in other phenolic poisonings with active bowel sounds, nausea and vomiting, severe metabolic acidosis, hypotension and cardiac and renal failure. The formulation of xylenol ingested contains alcohol which would facilitate absorption; due to the dangers of such poisonings care must be exercised as to access and exposure to xylenol sterilising agents.

Disinfectants↗
PubMed1985

The measurement of testosterone and oestradiol-17 beta using iodinated tracers and incorporating an affinity chromatography extraction procedure.

The development of sensitive radioimmunoassays (RIA) for testosterone and oestradiol-17 beta, utilising 125I-radioligands, is described. Use of an homologous bridge at the same site of attachment, for both the radioligand and the steroid-carrier protein conjugate employed in raising antibodies, normally results in a loss of assay sensitivity and precision. This was overcome in the oestradiol assay by utilising an heterologous configuration at the site of attachment (11 alpha vs 11 beta). In contrast, for testosterone, even though an homologous bridge and site of attachment was used for the radioligand and the steroid-carrier protein conjugate, a very sensitive assay with extremely high antibody titres (dilution of 1:2 X 10(6] was achieved. This finding was repeated with a different antiserum suggesting that the "bridge binding" phenomenon may be related to the position of attachment to the steroid molecule. In addition, an antibody-Sepharose 4B affinity chromatography extraction procedure has been developed for both oestradiol and testosterone. This approach allows the measurement of very low concentrations of steroids from large volumes of a variety of biological fluids. As antibody-linked Sepharose 4B uses high concentrations of antibody, steroids of similar structure are extracted from biological fluids. However, the cross-reactivity of these related steroids are very low in the RIA's, ensuring good specificity.

Animals↗
PubMed1985

Effect of sulphonylurea administration on insulin secretion and amino acid metabolism in non-insulin-dependent diabetic patients.

Sulphonylureas lower blood glucose but other metabolic effects have been little studied. In an assessment of carbohydrate and amino acid metabolism in 9 patients with non-insulin-dependent diabetes mellitus (NIDDM) before and after 3 months' therapy with gliclazide, glycaemic control was improved (mean +/- S.D. glycosylated haemoglobin 13.8 +/- 1.9% before therapy, 10.2 +/- 2.1% after therapy (p less than 0.01], but fasting amino acid levels were not altered. In contrast, postprandial levels of branched chain amino acids (BCAA) were significantly reduced: total BCAA (valine, leucine, and isoleucine) 120 mins following a standard test meal fell from 717 +/- 71 mumol/l before therapy to 600 +/- 90 mumol/l after 3 months' therapy (p less than 0.01). This finding implies an increased action of endogenous insulin on skeletal muscle to promote uptake of BCAA postprandially and, in accord with this, peripheral insulin levels were significantly increased following drug treatment (peak insulin level 55.6 +/- 20.2 mU/l before therapy, 91.3 +/- 17.9 mU/l after therapy (p less than 0.01]. Sulphonylurea drugs therefore do not simply have a hypoglycaemic action but also affect amino acid metabolism in NIDDM patients.

Adult↗
PubMed1983

Hyperkalaemia in patients in hospital.

Significant hyperkalaemia occurred in 406 out of 29 063 patients admitted to a major Scottish teaching hospital in one year (1.4%). Mortality was higher in these patients than in control patients and was strongly correlated with the severity of the hyperkalaemia. Overall seven deaths were directly due to hyperkalaemia (out of 58 deaths among patients with hyperkalaemia). Factors contributing to a poor prognosis were severity and speed of onset of hyperkalaemia and the presence of appreciable renal impairment. Patients with hyperkalaemia were older and more likely to be male; this trend was present in all diagnostic subcategories. Genitourinary disease, gastrointestinal disease, and cancer were significantly more common among the patients with hyperkalaemia than the controls. Hyperkalaemia due to drug treatment was invariably mild and non-fatal, whereas genitourinary disease was often associated with moderate to severe hyperkalaemia, which in two cases proved fatal. Use of electrocardiographic monitoring was rare, and although the treatment of hyperkalaemia was effective, it was often used when not required. Hyperkalaemia is a potential hazard in diabetic ketoacidosis, and use of potassium supplements should be carefully monitored during correction of the acidosis.

Diabetic Ketoacidosis↗
PubMed1982

Erythrocyte nucleoside transport: asymmetrical binding of nitrobenzylthioinosine to nucleoside permeation sites.

1. Nitrobenzylthioinosine is a potent and specific inhibitor of nucleoside translocation in animal cells. Kinetic and inhibitor binding studies were undertaken to clarify how this inhibitor interacts with the nucleoside transporter from human and nucleoside-permeable type sheep erythrocytes.2. [(3)H]nitrobenzylthioinosine inhibition of zero-trans [U-(14)C]uridine influx into nucleoside-permeable type sheep cells was consistent with simple competitive inhibition (apparent K(i) 1 nmol/l). Analysis of results using total inhibitor levels instead of cell-free inhibitor concentrations did not affect the inhibition pattern, but increased the apparent K(i) value by 5-fold.3. In contrast, [(3)H]nitrobenzylthioinosine was a non-competitive inhibitor of zero-trans [U-(14)C]uridine efflux (apparent Ki 1.5 nmol/l). Dipyridamole, another potent inhibitor of nucleoside translocation, also inhibited zero-trans [U-(14)C]uridine influx in a competitive manner (apparent K(i) 20-40 nmol/l).4. [(3)H]nitrobenzylthioinosine bound to high-affinity sites on cell membranes from human and nucleoside-permeable type sheep cells (apparent K(D) values approximately 1 nmol/l). Binding of inhibitor to these sites was competitively blocked by uridine, a well characterized substrate for the nucleoside transporter (apparent K(i) 1.25 and 0.9 mmol/l, respectively). These apparent K(i) values are close to the apparent K(m) for uridine equilibrium exchange in human erythrocytes.5. Similarly, deoxycytidine was found to be a competitive inhibitor of high-affinity [(3)H]nitrobenzylthioinosine binding activity (apparent K(i) 1.0 and 1.2 mmol/l for human and nucleoside-permeable type sheep cell membranes, respectively). This contrasts with a previous report that this nucleoside had no effect on inhibitor binding activity. Transport studies confirmed that deoxycytidine is a substrate for the erythrocyte nucleoside transporter. Apparent K(m) and V(max) values for [U-(14)C]-deoxycytidine zero-trans influx into human and nucleoside-permeable type sheep cells were comparable to those obtained for [U-(14)C]uridine.6. It is suggested from these results that nitrobenzylthioinosine competes directly with nucleosides for the permeation site of the nucleoside transporter, but that inhibitor binds preferentially to the external membrane surface.

Animals↗
PubMed1979

Residual astigmatism and visual acuity with hydrogel contact lenses: a comparative study.

Residual astigmatism, visual acuity, and transferred corneal toricity were measured in a double masked fashion on 24 randomly selected patients fitted with Buasch and Lomb Soflens contact lenses, the Hydrocurve II contact lenses, and the AOSoftTM hydrophillic contact lenses. None of the subjects had any contraindications to hydrogel lens wear. All three lens types produced a small but similar reduction in refractive astigmatism. However, because of residual astigmatism, fewer eyes achieved 20/20 or better visual acuity with each of the hydrogel lens types than with the best spectacle correction. Corneal toricity was found to be transferred to the front surface of all three lens types. Our findings indicate that generally these three types of hydrogel lenses result in similar residual astigmatism, visual acuity and transferred corneal toricity. However, individual differences may occur. Therefore, the choice of lens type should be based on the individual patient's response to various lens types.

Adult↗
PubMed1977

Problems with radiolabelling egg albumin for the Farr ammonium sulphate technique for antibody estimation.

High concentrations of passive haemagglutinating antibodies were raised in sheep immunised with egg albumin (Ea) in Feund's adjuvant. Further attempts to study the antigen binding capacities and avidities of these antisera by the Farr ammonium sulphate technique were hindered by unsuccessful attempts to label Ea with 125Iodine by either the chloramine T or sodium nitrite-HCl methods. This problem was attributed to the unavailability of tyrosine in the native protein. This was solved by labelling Ea with the Bolton-Hunter reagent which does not require the presence of tyrosine. However labelled Ea binds non-specifically to normal serum to give high control values of circa 40% binding. Despite this it was possible to estimate antibody concentrations and avidities of lamb sera.

Ammonium Sulfate↗
PubMedDate not supplied

Noise and the classical musician.

OBJECTIVES: To test the hypothesis that noise exposure may cause hearing loss in classical musicians. DESIGN: Comparison of hearing levels between two risk groups identified during the study by measuring sound levels. SETTING: Symphony orchestra and occupational health department in the west Midlands. MAIN OUTCOME MEASURES: Hearing level as measured by clinical pure tone audiometry. RESULTS: Trumpet and piccolo players received a noise dose of 160% and 124%, respectively, over mean levels during part of the study. Comparison of the hearing levels of 18 woodwind and brass musicians with 18 string musicians matched for age and sex did not show a significant difference in hearing, the mean difference in the hearing levels at the high (2, 4, and 8 KHz) audiometric frequencies being 1.02 dB (95% confidence interval -2.39 to 4.43). CONCLUSIONS: This study showed that there is a potential for occupational hearing loss in classical orchestral musicians.

Audiometry, Pure-Tone↗
PubMedDate not supplied

Using randomized designs to evaluate client-centered programs to prevent adolescent pregnancy.

CONTEXT: Interventions to prevent adolescent pregnancy (primarily curriculum-based programs) have not produced convincing evidence as to their success. Moreover, many evaluation approaches have been inadequate to assess program effectiveness. Therefore, rigorous evaluation of different kinds of interventions may help identify potentially effective strategies to prevent adolescent pregnancy. METHODS: An experimental design, in which clients were randomized to treatment and control groups, was used to evaluate the effects of a "client-centered" approach to reducing pregnancy among high-risk young people in seven communities in Washington State. Four projects served 1,042 youth (clients aged 9-13), and three served 690 teenagers (primarily clients aged 14-17). Projects offered a wide variety of services tailored to individual clients' needs, including counseling, mentoring and advocacy. RESULTS: On average, clients in the treatment group at youth sites received 14 hours of service, and their teenage counterparts received 27 hours; controls received only 2-5 hours of service. At one youth site, clients were less likely to intend to have intercourse after the intervention than before; at another, they became less likely to intend to use substances. Clients at one teenage project reported reduced sexual behavior and improved contraceptive use after receiving services; teenagers at another site reported reduced sexual intentions and drug use, and a greater intention to use contraceptives. The programs showed no other effects on factors that place young people at risk of becoming pregnant, including their sexual values and educational aspirations, communication with their parents (measured at youth sites only), and sexual and contraceptive behavior (assessed for teenagers only). CONCLUSIONS: High-risk clients likely need considerably more intervention time and more intensive services than programs normally provide. Rigorous evaluation designs allow continued assessment that can guide program modifications to maximize effects.

Adolescent↗
PubMedDate not supplied

Biological markers of exposure to SO2: S-sulfonates in nasal lavage.

S-sulfonate levels were measured in the nasal lavage (NAL) fluid of humans exposed to sulfur dioxide as a potential biological marker of exposure. These levels were determined by treating NAL fluid protein with cyanide to cleave the S-S linkage and release the sulfite. The cyanolytically released sulfite was measured by ion chromatography. In two experiments, humans were exposed to air or 1 ppm SO2 for 10 minute, and to air or 7 ppm SO2 for 20 minutes and lavaged immediately after exposure. Releasable sulfite levels in NAL fluid were 1.06 +/- 0.24 and 2.61 +/- 0.55 micrograms SO=3/mg protein, respectively (mean +/- SE, n = 5), for the first experiment, and 1.16 +/- 0.37 and 4.91 +/- 0.76 micrograms SO=3/mg protein, respectively (mean +/- SE, n = 8), for the second. The subjects in the former study were persons with asthma. In both experiments, S-sulfonate levels were statistically elevated in the exposed group compared with the control groups (p < 0.05, paired t-test). The same individuals in the second experiment received five additional 20-minute exposures to 7 ppm SO2 every other day, for a total of six exposures. NAL fluid taken at the conclusion of the final exposure had releasable sulfite levels of 4.99 +/- 1.36 micrograms SO=3/mg protein; these levels were statistically elevated relative to controls but were not elevated relative to the 1-day exposure (mean +/- SE, n = 8). The lack of accumulation of S-sulfonates after 6 days of short-term exposure suggests clearance of these compounds from the nasal passages within 24 hours. The levels of S-sulfonates observed in NAL fluid in this study are almost three orders of magnitude higher than those measured in plasma following similar SO2 exposures. Measurement of S-sulfonates in the nasal passage may be an effective short-term biomarker of exposure to SO2.

Adolescent↗
PubMedDate not supplied

Public health department tracking of high-risk drug users.

The Multnomah County (OR) Health Department received a National Institute on Drug Abuse grant to develop effective interventions and education to reduce the spread among injecting drug users of the human immunodeficiency virus that causes AIDS. One year into the project, new approaches were developed to locate the drug users for followup interviews. County data bases were accessed and arrangements were made to conduct interviews in jails and prisons. Similar techniques were employed to locate tuberculosis patients with positive results.

Acquired Immunodeficiency Syndrome↗