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Biomedical subjects

R Peters

Publications and source records attributed to R Peters.

At least 235 records · Page 13Linked to original sources
PubMed1987

Fate of salmonellas and competing flora in meat sample enrichments in buffered peptone water and in Muller-Kauffmann's tetrathionate medium.

Studies have been carried out in which growth patterns of a Salmonella sp. and competing micro-organisms, especially other Enterobacteriaceae, were followed during pre-enrichment in buffered peptone water (BPw) and subsequent selective enrichment in tetrathionate broth (TBB). Pre-enrichment cultures were inoculated with minced meat and three reference samples containing nalidixic acid-resistant salmonellas. Irrespective of their initial numbers in BPw, Enterobacteriaceae increased to 10(8)/ml or more. During incubation in TBB at 43 degrees C, numbers of lactose-positive Enterobacteriaceae decreased in most enrichments which resulted in a positive salmonella isolation, but remained constant in the majority of those that did not. Levels of lactose-negative Enterobacteriaceae did not decrease in most salmonella-positive tests, but did so in half of the salmonella-negative ones. In the salmonella-positive tests the numbers of salmonellas had increased to 10(3)-10(7)/ml in BPw and after transfer to TBB slowly reached 10(4)/ml or more. In all cases the numbers of salmonellas exceeded those of the competing flora on brilliant green agar (BGA). In the salmonella-negative tests the numbers of salmonellas had increased less in BPw and decreased in most of the TBB enrichments. In none of these negative tests did the numbers of salmonellas exceed those of the competing flora on BGA. Escherichia coli dominated in most of the salmonella-negative tests. The results suggest more influence of lactose-positive than lactose-negative Enterobacteriaceae on the detection of salmonellas. The effect of competing microorganisms seems to depend not only upon their initial numbers, but also upon the types that can interact with salmonellas during selective enrichment.

Culture Media↗
PubMed1987

A quantitative immunofluorescence test for detection of serum antibody to Sendai virus in mice.

A simple, semi-automated immunofluorescence assay, (TRACK XI), was developed for the detection and quantitation of circulating antibodies to Sendai virus in mice. The assay was validated by selecting Sendai virus-free and naturally infected mice from six different colonies and testing each serum in both ELISA and quantitative immunofluorescence (QIF) assays. The QIF test utilizes Sendai viral proteins immobilized within a dried colloid gel and permits serum antibody quantitation in 30 minutes. Using a dedicated fluorometer, antibody titers in test sera are calculated automatically from a three-point best fit calibration line. The QIF test gave 92.9% agreement with the ELISA and proved to be a reproducible, accurate and convenient assay for the quantitative measurement of serum antibody to Sendai virus in mice.

Animals↗
PubMed1987

Legal incompetents' need for guardians in Florida.

This study assesses the alleged need for guardians in Florida. A survey of the state's 74 public receiving facilities, community mental health centers, and clinics; 30 private receiving facilities; 11 Aging and Adult district offices; Developmental Services institutional and residential placements; and six state mental hospitals revealed that 11,147 persons in Florida reportedly need a legal guardian. The limitations, implications, and possible policy responses to this alleged need are discussed.

Community Mental Health Services↗
PubMed1987

Renal hemodynamics and excretory function of healthy young men during stimulation of their peripheral arterial chemoreceptors by almitrine bismesylate.

Renal hemodynamics and excretory function were studied using clearance-techniques in 13 healthy, normotensive, normoxic young men undergoing moderate osmotic diuresis. Each subject was measured in two experiments both lasting from 7:30 a.m. to 6:00 p.m. In one of them 50 mg almitrine bismesylate (Vectarion) was ingested at 12:00 o'clock, whereas the other test served as control. There were only negligible changes of the parameters measured in the control experiments. Immediately after ingestion of the drug a renal vasodilation occurred, but 2-3 h later renal hemodynamic resistance tended to increase. Urinary sodium excretion rose after administration of almitrine. Initially this increase seemed to be caused by the kidney vasodilation but between the 3rd and 6th hour after giving the agent a natriuresis occurred that resulted from inhibition of renal tubular sodium reabsorption. The maximum of this renal tubular response was apparently not reached at the end of the experiments, i.e. 6 h after oral administration of the drug. Almitrine did not increase the renal potassium excretion. The data indicate that pharmacological stimulation of the peripheral arterial chemoreceptors by almitrine bismesylate in normoxic healthy humans causes reflectorically a slight renal vasoconstriction and a long-lasting inhibition of renal tubular sodium reabsorption. These findings are in good agreement with previously published data obtained in animal experiments.

Adult↗
PubMed1986

Molecular mobility and nucleocytoplasmic flux in hepatoma cells.

Fluorescence microphotolysis (photobleaching) was used to measure, in single polyethylene glycol-induced polykaryons of hepatoma tissue culture cells, nucleocytoplasmic flux and intracellular mobility for a series of dextrans ranging in molecular mass from 3 to 150 kD and for bovine serum albumin. For the dextrans, the cytoplasmic and the nucleoplasmic translational diffusion coefficients amounted to approximately 9 and approximately 15%, respectively, of the value in dilute buffer. The diffusion coefficients depended inversely on molecular radius, suggesting that diffusion was dominated by viscosity effects. By application of the Stokes-Einstein equation, cytoplasmic and nucleoplasmic viscosities were derived to be 6.6 and 8.1 cP, respectively, at 23 degrees C. Between 10 and 37 degrees C nucleoplasmic diffusion coefficients increased by approximately 45-85%, whereas cytoplasmic diffusion coefficients were virtually independent of temperature. In contrast to that of the dextrans, diffusion of bovine serum albumin was more restricted. In the cytoplasm the diffusion coefficient was approximately 1.5% of the value in dilute buffer; in the nucleus albumin was largely immobile. This indicated that albumin mobility is dominated by association with immobile cellular structures. Nucleocytoplasmic flux of dextrans depended inversely on molecular mass with an exclusion limit between 17 and 41 kD. This agrees with previous measurements on primary hepatocytes (Peters, R., 1984, EMBO [Eur. Mol. Biol. Organ.] J. 3:1831-1836), suggesting that in both cell types the nuclear envelope has properties of a molecular sieve with a functional pore radius of approximately 55 A.

Animals↗
PubMed1986

Distinguishing complicated from uncomplicated bacteremia caused by Staphylococcus aureus: the value of "new" and "old" serological tests.

Antibody responses to staphylococcal alpha-toxin, cell wall teichoic acid, and cell wall peptidoglycan were measured in 259 serum samples from 74 consecutive patients with Staphylococcus aureus bacteremia. All patients with complicated bacteremia were seropositive in at least one of three tests, and 18 (72%) of 25 were positive in two or three assays; six (75%) of eight patients with endocarditis were positive for all three tests. In contrast, 15 (75%) of 20 patients with uncomplicated bacteremia were positive in only one or none of the tests. These differences in antibody response patterns were statistically significant (chi 2 = 18.33, P less than .001). Patients with complicated bacteremia had peak antibody titers that were significantly higher than those of patients with uncomplicated bacteremia. The assay for antibody to alpha-toxin was as sensitive as the assays for antibody to cell wall antigens but had less specificity for complicated bacteremia. The clinical severity of the bacteremia did not correlate with a complicated vs. uncomplicated nature of the infection but was predictive of early death due to staphylococcemia. The calculated predictive values suggest that the serology of S. aureus bacteremia may be clinically valuable when multiple tests are performed in paired serum samples.

Antibodies, Bacterial↗
PubMed1986

A computer information system in a suicide prevention centre.

The process of planning and implementing a computer information system in a suicide attempt counselling service is described. The discussion highlights the importance of: involving line workers at all stages, clearly defining the uses the data will be put to, and establishing a forum for periodic reviews of the system. The hardware and software options we elected to choose are also described.

British Columbia↗
PubMed1985

Single-cell flux measurement by continuous fluorescence microphotolysis.

Continuous fluorescence microphotolysis (CFM) was adapted to flux measurements in single cells. The principle of the method is simple: Cells are equilibrated with a fluorescent solute, an individual cell is continuously irradiated by a laser beam focussed down to approximately the diameter of the cell, and fluorescence originating from the irradiated cell is monitored. In this procedure irradiation irreversibly photolyzes chromophores in the cell while fresh chromophores enter the cell by membrane transport (flux). The resulting fluorescence decay can be analyzed for the rate constants of both membrane transport and photolysis. As an experimental test of the new method the band-3 mediated transport of the fluorescent anion N-(7-nitrobenzofurazan-4-yl)-taurine (NBD-taurine) across the erythrocyte membrane was measured. For various experimental conditions good agreement between values obtained by CFM and by fluorescence microphotolysis (FM) was observed. By measurements on single ghosts it was furthermore found that photolysis of NBD-taurine is first-order with respect to the power of irradiation. On this basis a stepped-intensity procedure was worked out that facilitates data evaluation in flux measurements. Also, by analysing the relations between CFM and FM flux measurements a method was devised by which FM data can be corrected for (inevitable) photolysis.

Cells↗
PubMed1985

Leaving a cardiology service against medical advice.

In an exploratory retrospective study of 64 hospitalized patients, we examined the demographic, medical, and psychologic correlates in patients who left our Cardiology Service against medical advice (AMA). Based on a medical chart review, the AMA and control groups were found to be significantly different regarding prior cardiac disability level, physical signs of chronic alcohol abuse on admission, cardiac complications, and requirement of antihypertensive/diuretic medications while hospitalized. The two groups were also significantly different with regard to somatic complaints, apparent anxiety and use of psychotropic medication on the day before leaving against medical advice. This study indicates that a multifactorial assessment of patients hospitalized on a cardiology service can enhance identification of those at risk to leave the hospital against medical advice.

Adolescent↗