Search PubMed⌕ Search

Biomedical subjects

R White

Publications and source records attributed to R White.

At least 703 records · Page 39Linked to original sources

Evaluation of the NASA/JSC blood pressure screening clinic.

This study evaluated the NASA/Johnson Space Center's blood pressure screening program, which was designed to identify the proportion of NASA employees who were hypertensive and to identify self-report variables related to elevated pressures. In 1978, a random sample of 3892 employees was selected from over 2,100 NASA employees. Twenty-eight percent were classified as hypertensive by the criterion of systolic pressure of 140 or above or diastolic pressure of 90 or greater. Approximately 16% of all employees had a history of hypertension; the remaining 12% of the identified hypertensives were unaware of their potential health problem. Multivariate analysis showed that elevated systolic pressures were more prevalent in the older, heavier employees. Of hypertensives under treatment, about 74% were under poor control as judged from blood pressures randomly taken at their place of employment. These results demonstrated the effectiveness of screening for unsuspecting hypertensives in industry.

Adult↗

Comparison of five methods for the assay of serum gentamicin.

The microbiological bioassay, the adenylation method, and the radiometric, enzyme, and fluorescent immunoassay methods for assaying serum gentamicin were compared. The precision, reproducibility, and specificity of each method was assessed and proved satisfactory, with the exception of the radioimmunoassay, which gave artificially high results. Good correlations between the other four methods was obtained in a comparison involving 103 patient sera. The other aspects of performance were also compared, namely, simplicity, speed, cost, ease of automation, and application to large and small workloads. The enzyme immunoassay performed best in this comparison, being accurate, specific, rapid, and very simple to perform. However, other laboratories might find that workload, staffing, and available equipment make other methods more attractive.

Adenosine↗

Central venous bubbles and mixed venous nitrogen in goats following decompression.

Decompression of awake goats from saturation at 1, 2, and 3 ATA of air has been carried out using ultrasonic Doppler bubble detection, central venous blood inert gas measurement, and cardiac output measurement. The results of these experiments indicate that the decrease in nitrogen elimination rate as an apparent result of decompression cannot be due to excessive cardiac output or mass transport of a large amount of inert gas to the lungs as bubbles. Rather, the rapid drop in mixed venous nitrogen content is consistent with a generalized decrease in tissue-to-blood nitrogen elimination. This in turn appears to be due to a cardiovascular response to the decompression insult as was previously reported for dogs (D'Aoust et al., J. Appl. Physiol. 41: 348--355, 1976) at 1, 2, and 3 ATA; addition of ultrasonic Doppler monitoring and cardiac output in the present studies allowed measurement of the degree of latency in the appearance of bubbles at a central venous location. This time period includes that required for bubble formation, growth, and vascular transport of the bubbles to the Doppler detector. All results of these studies are consistent with the interpretation that due to a decompression insult, which probably includes bubble formation, some degree of hemostasis, and other hematologic sequelae, the transport of tissue inert gas to the capillary venous blood is retarded, thus providing the rapid apparent decrease in mixed venous blood inert gas content. These results demonstrate what is most likely a general response to a severe but not crucial decompression by the cardiovascular system.

Animals↗

Secretion of alpha 1-proteinase inhibitor by cultured rat alveolar macrophages.

Alpha 1-proteinase inhibitor, metabolically labeled with 35S, was detected in concentrated culture medium of rat alveolar macrophages by immunoelectrophoresis autoradiography. The metabolically labeled macrophage alpha 1-proteinase inhibitor had the same electrophoretic mobility as did pure rat serum alpha 1-proteinase inhibitor. Moreover, monospecific antiserum to rat serum alpha 1-proteinase inhibitor precipitated a 35S-labeled protein from macrophage culture supernates, and this protein was shown by sodium dodecyl sulfate polyacrylamide gel electrophoresis to have a molecular weight close to that of rat serum alpha 1-proteinase inhibitor. Cycloheximide (an inhibitor of protein synthesis) at a concentration of 0.50 micrograms/ml, inhibited secretion of labeled inhibitor. This, cultured rat alveolar macrophages secrete detectable concentrations of a proteinase inhibitor believed to play a major role in lung defense.

Animals↗

Nonlinear pharmacokinetics of misonidazole and desmethylmisonidazole in the isolated perfused rat liver.

Dose-dependent elimination of misonidazole (MISO) and its metabolite desmethylmisonidazole (DESMISO) were investigated in the isolated perfused rat liver and saturation kinetics were observed for both compounds. The simplest model which accurately described the DESMISO clearance from the perfusate consisted of a saturable elimination pathway (Vmax 3 = 32 nmol/min, Km3 = 11 micro M) in parallel with a first-order pathway [CL5 (clearance) = 0.21 ml/min]. A similar model was constructed for MISO (Vmax2 = 110 nmol/min, Km2 = 10 micro M, CL4 = 0.36 ml/min), but required an additional saturable pathway (Vmax1 = 226 nmol/min, Km1 = 1850 micro M) to characterize the generation of DESMISO, as suggested by in vitro microsomal studies. A good correlation was demonstrated between DESMISO perfusate concentrations (generated during the course of MISO perfusion) and simulations based on the MISO model which included the microsomal data. The MISO and DESMISO models demonstrate that the relative contributions of the different pathways for MISO and DESMISO elimination are strongly concentration-dependent and that the MISO leads to DESMISO pathway is a minor route. A qualitative similarity in saturation kinetics was observed in the disappearance curves for both MISO and DESMISO from the liver perfusate. MISO In combination with an excess of DESMISO resulted in a marked decrease in the clearance rate of MISO from the liver perfusate. This observation suggest that MISO and DESMISO are metabolized along similar pathways.

Animals↗

Effect of surface porosity on early thrombogenicity using vascular grafts with two surfaces in sequence.

This experiment addresses the multifactorial dilemma of defining the ideal performance parameters of small internal diameter vascular grafts. We found silicone rubber vascular grafts with smooth surfaces remain acutely free of thrombotic deposits whereas grafts with rough surfaces promote a dispersed thrombus formation. This study also questions the concept that the thrombogenicity of one surface determines the thrombotic response of different and adjacent flow surfaces in the blood flow. Here the distinction between response to each surface was abruptly delineated and equal in intensity regardless of proximal or distal positioning. By studying the 2 surfaces in sequence, surface properties were evaluated using the minimal number of experiments by mitigating the effects of interanimal variability. This is an important consideration in an era of "cost accountability".

Animals↗

Androgenic regulation of messenger RNA in rat epididymis.

1. The regulation by testosterone of mRNA complexity and mRNA activity was investigated in rat caput and cauda epididymidis. 2. The sequence complexity of cytoplasmic poly(A)-containing RNA from normal rats was determined by homologous hybridization with radiolabelled complementary DNA probes by using RNA in excess. Computer analysis of results suggested that hybridization could best be described by curves composed of two components distinguished by their relative abundance. Thus caput-epididymidal RNA consists of approx. 260 moderately abundant and 16400 scarce sequences, whereas cauda-epididymidal RNA consists of approx. 124 moderately abundant and 13400 scarce sequences. Judging by heterologous-hybridization reactions, castration did not result in appreciable alterations in either sequence complexity or the relative abundance of the two classes of poly(A)-containing RNA. 3. To investigate if individual mRNA sequences were regulated by androgens, mRNA was translated in a cell-free system derived from reticulocyte lysate. Since most of the translation products had a different mobility on sodium dodecyl sulphate/polyacrylamide gels from the authentic proteins synthesized in tissue minces, antibodies were used to identify specific translation products. Antibodies to the two related major proteins (mol.wt. 18500 and 19000) secreted by the caput epididymidis and whose synthesis is stimulated by testosterone both precipitated a single translation product of mol.wt. 21000. That this polypeptide was a precursor to the secreted proteins was suggested by the fact that the addition of microsomal membranes isolated from dog pancreas resulted in the appearance of a polypeptide of mol. wt. 19000. 4. Translation of RNA from the caput epididymidis of rats of different hormonal status showed that mRNA activity for the 21000-dalton polypeptide declined after castration, but could be restored by treating rats with testosterone. 5. It is concluded that testosterone stimulates the synthesis of a major protein secreted by the caput epididymidis by regulating its mRNA activity.

Animals↗

Cloning and characterization of androgen-dependent mRNA from rat ventral prostate.

DNA complementary to three androgen-dependent mRNAs from rat ventral prostate has been cloned in the bacterial plasmid pAT 153. DNA sequences coding for 20,000, 10,000, and 9,000 translation products, the precursors of polypeptides secreted in vivo (Parker, M. G., and Scrace, G.T. (1979) Proc. Natl. Acad. Sci. U.S.A. 76, 1580--1584) were identified in recombinant plasmids. The levels of mRNA coding for the 20,000 and 10,000 translation products were quantitated using cDNA probes and also by hybridization in situ with RNA that had been covalently bound to diazobenzyloxymethyl paper. Both mRNAs responded with similar kinetics to androgen withdrawal and testosterone stimulation. The sequences declined with nonlinear kinetics by at least 3 orders of magnitude after androgen withdrawal and are induced by testosterone without an appreciable lag, a 3-fold increase being detectable within 2 h. Analysis of the RNA bound to diazobenzyloxymethyl paper indicates that the mRNAs coding for the 20,000, 10,000, and 9,000 translation products contain 930, 640, and 550 nucleotides, respectively.

Animals↗

A highly polymorphic locus in human DNA.

A locus in the human genome, not associated with any specific gene, has been found to be a site of restriction fragment length polymorphism. The polymorphism was found by hybridizing a 16-kilobase-pair segment of single-copy human DNA, selected from the human genome library cloned in phage lambda CH4A, to a Southern transfer of total human DNA digested with EcoRI. DNAs from a number of individuals from within Mormon pedigrees as well as random individuals have been examined. The locus is highly variable, with at least eight alleles present, homozygotes accounting for less than 25% of the individuals examined. The polymorphism appears to be the result of DNA rearrangements rather than base-pair substitutions or modifications. Examination of the DNA from seven members of a family revealed fragment lengths that are consistent with their inheritance as Mendelian alleles through three generations.

DNA↗

An influenza outbreak due to A/USSR/77-like (H1N1) virus aboard a US Navy ship.

An explosive outbreak of influenza caused by an A/USSR/77-like (H1N1) virus occurred aboard a US Navy ship in December 1977 and January 1978. Two hundred volunteers aboard the ship were studied. Virus was isolated from 36 of 57 patients from whom isolation was attempted. Among virologically confirmed patients, headache (97%), chills (92%), malaise (86%), and cough (75%) were the most frequent symptoms. There were two virologically confirmed cases with complications: one with collapsed lung and the other with pneumonitis. The study subjects were 25 years of age or less, but there was little influenza-like disease in members of the crew greater than 25 years of age. Prior vaccination with bivalent vaccine, containing A/NJ/76 (Hsw1N1) virus, did not offer significant protection against disease caused by A/USSR/77-like virus. Serologic tests, either or both complement fixation and hemagglutination inhibition, were positive in only 14 of 22 virologically confirmed cases, indicating a poor serologic response to primary infection with this strain of virus. These findings prevented calculation of meaningful disease to infection ratios. However, inapparent infection occurred in 3 of 19 (16%) individuals who denied having illness during the outbreak yet had serologic evidence of recent influenza infection.

Adolescent↗

Pneumatic power supply for intravenous infusions.

The pneumatic power supply (PPS) has been used as the driving device for the pneumatic blood pump during the resuscitation of more than 15 hypovolemic patients. The device has been found to be safe and easy to use. By virtue of its semiautomatic function, members of the resuscitation team are free to perform other duties. Previously, these individuals would have been required to maintain an adequate driving pressure in the infusion pumps.

Chlorofluorocarbons, Methane↗