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Biomedical subjects

R Armstrong

Publications and source records attributed to R Armstrong.

At least 109 records · Page 6Linked to original sources
PubMed1981

Atrial flutter associated with acute myocardial infarction.

Between 1966 and 1968, 35 of 340 patients (10.3 percent) admitted to the Los Angeles County-University of Southern California Medical Center with documented myocardial infarctions were noted to have atrial flutter while being monitored in the coronary care unit. This incidence is higher than that found in most previous studies. Patients with atrial flutter had significantly higher mortality than infarction patients without flutter (P <0.05). The increased mortality for those with flutter was apparently the result of concurrent complications and probably not because of the arrhythmia alone. Atrial flutter recurring for more than one day was associated with further increase in mortality (P <0.02). Also, there was a higher death rate among patients with flutter who had anterior infarctions than among those with inferior infarctions, but the difference was not statistically significant. Most patients responded to treatment with antiarrhythmic drugs, but prior digitalis therapy apparently did not prevent the onset of atrial flutter.

Adult↗
PubMed1980

Cytotoxic lymphocytes and antibody-dependent complement-mediated cytotoxicity induced by administration of influenza vaccine.

Recently defined aspects of cellular and humoral antiviral immunity were evaluated in 10 young adults given influenza vaccines containing A/USSR/77 (H1N1) antigens. Cytotoxic lymphocytes were measured by using cryopreserved lymphocytes as effector cells and syngeneic, virus-infected lymphocytes as target cells. An assay previously developed in this laboratory was adapted for the measurement of antibody-dependent, complement-mediated cytotoxicity. Antiviral cytotoxic lymphocyte responses were detected in 5 of 10 volunteers between 3 and 10 days after the initial vaccination. These responses were found both in individuals who were previously primed and in individuals who were not primed to influenza A/USSR/77 antigens. The complement-mediated lysis assay was found to be more sensitive than the hemagglutination inhibition test and probably detected antibodies to both subtype-specific and cross-reactive antigenic determinants. These responses to influenza antigens are similar to those obtained in studies of murine influenza which indicate that cytotoxic lymphocytes and antibody-dependent, complement-mediated cytotoxicity have a role in the early response to acute infection.

Adult↗
PubMed1979

Hepatic microsomal epoxide hydrase. Chemical evidence for a single polypeptide chain.

Highly purified hepatic microsomal epoxide hydrase, which had been purified in the presence of proteolytic enzyme inhibitors, was subjected to carboxypeptidase Y digestion, automated Edman degradation, and carbohydrate analysis. Carboxypeptidase Y digestion resulted in the near stoichiometric release of leucine, the COOH-terminal amino acid. Automated Edman degradation permitted the identification of the first 20 amino acid residues of epoxide hydrase. Methionine was identified as the NH2-terminal residue. The NH2-terminal region of epoxide hydrase is similar in hydrophobicity to the NH2-terminal precursor segments of several secretory proteins and the NH2-terminal regions of several microsomal cytochromes P-450. Carbohydrate analyses of the enzyme revealed the presence of 0.5 to 1.0 mol of mannose/50,000 g of protein. These results provide evidence for the presence of a single polypeptide chain in our purified enzyme preparations and suggest that there may be only one enzymic form of epoxide hydrase in microsomes from phenobarbital-treated rats.

Amino Acid Sequence↗
PubMed1978

Air embolism occurring as a complication of central venous catheterization.

Two patients with air embolism (one fatal) which occurred during intravenous feeding with a central venous catheter are reported. The connection between intravenous administration sets and such catheters is shown to be a danger area which requires further technological improvement. The world literature concerning this hazard is reviewed.

Catheterization↗
PubMed1977

Complement and Fc receptors on cord blood and adult neutrophils.

The percentage of neutrophils forming erythrocyte-antibody-complement complex (EAC) and with erythrocyte-antibody complex (EAG) was determined for 30 normal newborns and 10 normal adults. The cord values ranged from 84-100% EAC binding cells with a mean of 95%. The adult values ranged from 89-100% EAG binding cells with a mean of 96% rosetted neutrophils. The mean percentage of EAG binding cells in the cord samples was 81%, whereas in the seven adult samples the mean was 87%.

Adult↗
PubMed1975

Coronary bypass surgery. Value of maximal exercise testing in assessment of results.

To evaluate the relationship of results of maximal treadmill testing and results of saphenous vein bypass surgery (SVG), 30 patients underwent a maximal treadmill test before and after SVG; an additional 39 had results of postoperative exercise testing available. These patients were part of a group of 91 patients (95% of 96 survivors) who had complete right- and left-heart catheterizations and coronary angiography before and after operation. Twenty-one per cent had improved ejection fractions postoperatively; in 32% ejection fractions were worse. Duration of maximal treadmill exercise correlated poorly with ejection fraction changes or graft patency. Rate-pressure product (RPP) was usually lower postoperatively in patients with worse ejection fractions, primarily because of a low systolic blood pressure at maximum exercise. RPP postoperatively of less than 25,000 almost always meant poor surgical results, either graft occlusion or poor left ventricular function, while RPP of more than 30,000 meant that left ventricular function was preserved and all grafts or the graft to the anterior descending were patent. Thus, success or failure of SVG in these groups may be predicted without postoperative catheterization. An open graft to the anterior descending coronary generally insured a high RPP with exercise, even if other grafts were closed, as long as ventricular function remained good.

Angina Pectoris↗
PubMed1970

Contemporaneous disequilibrium, a new hypothesis to explain the "paradox of the plankton".

The diversity of lake phytoplankton is unexpectedly high, since the epilimnion of a lake is continuously mixing and might be expected to have only one or at most a few niches for primary producers. However, a carefully replicated series of samples from Castle Lake, Calif., showed a high degree of patchiness for many phytoplankton species, indicating that the rate of mixing is slow enough relative to the reproductive rate of the algae for many different niches to exist simultaneously. Productivity per unit biomass ratios, measured at Lake Tahoe, California-Nevada, shows that the turnover times for carbon in even this ultraoligotrophic lake are often less than 1 day. High diversity is associated with high productivity per unit biomass and high zooplankton populations in this lake.A contemporaneous disequilibrium model to explain the diversity of the lake phytoplankton is therefore highly plausible. At any one time, many patches of water exist in which one species is at a competitive advantage relative to the others. These water masses are stable enough to permit a considerable degree of patchiness to occur in phytoplankton, but are obliterated frequently enough to prevent the exclusive occupation of each niche by a single species.

California↗