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Biomedical subjects

R Barlow

Publications and source records attributed to R Barlow.

At least 37 records · Page 2Linked to original sources
PubMed1993

Platelet activating factor, lyso-platelet activating factor and arachidonic acid release in normal human skin and the influence of topical steroid treatment.

1. Previous, in vitro, studies have established the synthesis of platelet activating factor (PAF) by the 're-modelling' pathways in which the activation of a phospholipase A2 (PLA2) enzyme catalyses the hydrolysis of an ether-acyl-phosphocholine to give concomitant release of lyso-PAF, the immediate precursor of PAF, and arachidonic acid, the precursor of the icosanoids. The aim of this study was to investigate the relationship between PAF and eicosanoid release in human skin, and to study the effect of treatment of skin with a topical steroid, on the release of PAF, lyso-PAF and arachidonic acid. 2. A novel assay procedure was developed for the simultaneous assay of PAF and lyso-PAF in skin exudates from abrasions and suction blisters in normal human skin. In addition we assayed arachidonic acid and prostaglandin E2 (PGE2), a representative eicosanoid. 3. The mean amounts of mediator recovered in the first 30 min period following abrasion were PAF 0.43, lyso-PAF 11.9, PGE2 25.7 and arachidonic acid 760 pmol/sample. The molar ratio of PAF:lyso-PAF:arachidonic acid in skin exudates from abrasions was 1:30:1800 and in suction blister exudates was 1:90:3660. 4. Time course studies showed a decline in the recoveries of arachidonic acid and lyso-PAF, of about 50% in 2 h. In contrast, PAF was recovered in exudates at a constant rate over 2 h but PGE2 release decreased by more than 90% after the initial 30 min period. 5. Topical application under occlusion, of 0.05% clobetasol propionate, a potent corticosteroid, significantly reduced lyso-PAF by 30% in suction blister exudates but did not significantly alter the concentrations of PAF or arachidonic acid.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Topical↗
PubMed1993

Increased interleukin 6, but reduced interleukin 1, in delayed pressure urticaria.

Interleukin 1 (IL-1) and interleukin 6 (IL-6) were measured by bioassays in suction-blister exudates from lesional skin, from skin immediately following a pressure challenge, and from control skin (not subjected to pressure) of patients with delayed pressure urticaria. IL-6 activity in lesional exudates was significantly higher than in exudates from the other two sites. IL-1 activity in lesional exudates was not significantly higher than in the control exudates, but significantly less IL-1 activity was found immediately after pressure challenge than from the control site.

Adult↗
PubMed1993

OSHA's final bloodborne pathogens standard: Part II.

The Bloodborne Pathogens Standard has specific requirements for employee hazard communication and training as well as management of regulated waste, contaminated laundry, and housekeeping procedures. OSHA recognizes the benefits of prophylactic use of hepatitis B vaccine and requires that it be made available, at no charge, to all employees who have occupational exposure to blood or other potentially infectious materials. The goal of the Bloodborne Pathogens Standard is to reduce the occupational risk of morbidity and mortality associated with diseases such as hepatitis B and human immunodeficiency virus (HIV).

Health Personnel↗
PubMed1992

Homozygous hereditary C3 deficiency due to a partial gene deletion.

The molecular mechanism of C3 deficiency in an Afrikaans patient with recurrent pyogenic infections was studied. Restriction enzyme analysis showed a gene deletion of 800 base pairs (bp) mapping to the alpha chain of C3. Amplification of genomic DNA, using the PCR, demonstrated that the deletion included exons 22 and 23 of the C3 gene. Truncated mRNA was shown in an Epstein-Barr virus-transformed B-cell line by PCR amplification of first-strand cDNA. A consequence of this deletion was that the RNA transcribed 3' to the deletion was out of frame, resulting in formation of a stop codon 19 bp downstream from the deletion. The molecular basis of the deletion was compatible with homologous recombination between two Alu sequences located in introns 21 and 23. An unrelated nonconsanguineous relative and two of a sample of 174 Afrikaans-speaking individuals were heterozygous carriers of the same gene deletion. The wide prevalence of this null allele in this population is probably due to the effects of a small founder population. The presence of this deletion in the C3 gene is not compatible with production of any functional C3, supporting the idea that study of such patients offers a valid model for understanding physiological activities of C3 in vivo in humans.

Base Sequence↗
PubMed1992

OSHA's final bloodborne pathogens standard. Part I.

The Bloodborne Pathogens Standard is the first standard promulgated by OSHA that addresses a biological hazard in the workplace. This Standard applies to all workers with occupational exposure to blood or other potentially infectious materials. To achieve compliance, the employer must determine and document exposure. Also, a written exposure control plan must be available that stipulates the use of appropriate methods of compliance such as engineering controls, work practice controls, and the use of personal protective equipment.

Humans↗
PubMed1992

Role of the occupational health nurse in the year 2000: perspective view.

From a historical perspective, occupational health nursing practice has changed in response to historic events and societal needs. The occupational health nurse today is expected to meet a variety of challenges and assume various roles within occupational health service settings. These roles require a sophisticated knowledge base and problem solving skills which are empirically based and multidisciplinary in their approach. The occupational health nurse can effect on local and public health issues through research and influence on public values and opinion. With the increasing demand for health care cost containment, occupational health nurses must meet the challenges of today and those of the future through program planning, research, and policy making.

Forecasting↗
PubMed1990

Enantiomers: how valid is Pfeiffer's rule?

In the 1950s Pfeiffer observed that the relative potencies of the enantiomers (mirror-image isomers) of several drugs appeared to be related to the dose of the racemate used clinically. The difference was greatest with the most active compounds and he suggested reasons for what has become known as 'Pfeiffer's rule'. In this short article Dick Barlow points out that there is a corollary to the rule - that the activity of the weaker enantiomer is determined by the activity of the more potent one - which is intuitively imporbable. With more examples and in a simpler situation, the picture is more complex and there are marked exceptions. The ideas behind Pfeiffer's rule overlook differences in molecular flexibility and there is a need for a revised model that takes entropy differences into account, particularly as recent developments in the elucidation of receptor structure are likely to revive interest in Pfeiffer's rule.

Pharmacology↗
PubMed1982

Denervation modulated changes in mouse skeletal muscle RNA concentration.

We have examined normal and denervated mouse skeletal muscle for histological evidence of changes in RNA concentration using acridine orange/nucleic acid fluorescence. In denervated muscle, cytoplasmic RNA concentration increases dramatically. The earliest increase is in the subsarcolemmal region, 7 days after denervation. By 28 days after denervation, the increase in RNA is distributed throughout the cytoplasm of the atrophic cells, non-atrophic cells show little or no increase. Prior to the increase in cytoplasmic RNA concentration, many myocyte nuclei exhibit enlarged nucleoli, indicative of active ribosomal RNA synthesis. Such active nucleoli are present throughout the 42 day study period. We conclude that both new RNA synthesis, and preferential accumulation of cytoplasmic RNA are prominent events in denervation atrophy. There is an ordered progression from nucleolar synthesis to subsarcolemmal accumulation to diffuse accumulation in atrophying cells. These observations complement biochemical findings of others which indicate an increase in both RNA and protein synthesis after denervation.

Animals↗
PubMed1979

Accurate measurement of liver, kidney, and spleen volume and mass by computerized axial tomography.

Computerized axial tomography permits accurate cross-sectional radiographic visualization of visceral organs. Thus, "radiographic area" of an organ slice can be calculated and converted to actual area from a standard grid printed on the roentgenogram. Because the width between slices is known, the volume of an organ slice can be calculated as area times width. Mass of the organ slice is then the product of slice volume and organ density, and entire mass of the organ is the sum of the masses of all the organ slices. The validity of this method was examined in four water-filled balloons, in 12 excised human cadaver organs (six kidneys, three livers, and three spleens), and in two human cadavers while the organs (four kidneys, one liver, and two spleens) remained in situ. Radiographic volume and mass agreed with actual volume and mass within +/- 3% to 5%, thus confirming the accuracy of this method.

Humans↗
PubMed1976

Applications of a health planning model in Morocco.

It is argued in this paper that public health planning should be guided by the principle of output maximization. The objective of the health sector should be specified, and measurable forms of output should be derived from these statements of purpose. Knowledge of the contributions which given combinations of inputs make toward output thus defined allow, in principle, calculation of the particular deployment of the avilable inputs which will maximize output. There is a discussion of the objectives or forms of output in a public health system, both humanitarian and economic. A verbal model of such a system for an underdeveloped country is constructed which identifies the relationships which must be known if spending decisions are to suceed in maximizing output. An attempt is then made, in the context of the Moroccan public health system, to show that the model is not merely a theoretical exercise, but is potentially useful as a planning instrument. The respective contributions of general hospitals and of mass vaccination programs toward the objective of reducing mortality are estimated. On the whole, the preventive activities (the mass vaccinations) are found to be a much a cheaper way of saving lives than are the curative activities (the general hospitals).

Costs and Cost Analysis↗
PubMedDate not supplied

Anesthesia can cause sustained hyperglycemia in C57/BL6J mice.

Effects of anesthesia on the blood glucose of C57/BL6J mice were evaluated under conditions commonly used for testing retinal sensitivity with electroretinographic (ERG) recordings. We evaluated the effects of four anesthetics: nembutal (50 mg/kg), pentothal (100 mg/kg), avertin (240 mg/kg), and ketamine/xylazine (100 mg/kg) using saline as control. We measured blood glucose (BG) levels from tail vein blood before and 15 and 60 min following intraperitoneal injections. Fifteen minutes postinjection, all four anesthetics and saline elevated BG with ketamine/xylazine and avertin having substantially greater effects than nembutal, pentothal, and saline. Only the effects of ketamine/xylazine and avertin persisted throughout the test period. Sixty minutes after injecting ketamine/xylazine BG remained elevated at 400 +/- 42 mg/dl, a 167% increase over preinjection levels. Sixty minutes after injecting avertin BG was 288 +/- 10 mg/dl, a 59% increase over preinjection levels. No sustained elevation in BG was detected 60 min following injection of nembutal, pentothal, or saline. Because BG can affect the amplitude of the ERG, caution should be exercised in the use of ketamine/xylazine or avertin. The choice of anesthesia may also be important in diabetes and metabolism research where changes in blood glucose could impact physiological processes.

Anesthesia↗