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Biomedical subjects

L Graham

Publications and source records attributed to L Graham.

At least 37 records · Page 2Linked to original sources
PubMed1987

Bradyrhizobium japonicum mutants defective in nitrogen fixation and molybdenum metabolism.

Bradyrhizobium japonicum JH mutants deficient in molybdenum metabolism into the enzymes nitrogenase and nitrate reductase were isolated by using the vector pSUP1011, which carries transposon Tn5 (streptomycin and kanamycin resistance). Mutants in Mo metabolism were obtained at a frequency of 3.6 X 10(-3) (per Kan Strr colony). The mutants were detected by their poor ability to grow in nitrate-containing medium without added Mo. One of the mutant types required 10(5) times more molybdate than the wild type to obtain maximal nitrogen fixation activity. Double-reciprocal plots of Mo uptake versus concentration indicated that the wild-type strain had a high- and a lower-affinity component for Mo binding. Mutant strains JH-90 and JH-119 lacked the high-affinity Mo uptake component and were also clearly deficient in Mo accumulation into a nonexchangeable form. Nitrogenase activity as well as Mo uptake ability could be restored in strains JH-90 and JH-119 by the addition of the sterile supernatant fraction of the wild type. Therefore, mutant strains JH-90 and JH-119 appeared to be deficient in an extracellular Mo-binding factor produced by the wild type. Mutant strains JH-14 and JH-143 had Mo uptake kinetics like those of the wild type (both high- and low-affinity binding for Mo) and appeared to be deficient in intracellular Mo metabolism processes. The addition of the wild-type supernatant did not restore Mo uptake or nitrogenase activity in these strains.

Biological Transport↗
PubMed1987

Variability in molybdenum uptake activity in Bradyrhizobium japonicum strains.

Twenty naturally occurring strains of Bradyrhizobium japonicum in 11 serogroups were screened for the ability to take up Mo as bacteroids from soybean root nodules. The strains varied greatly in their ability to take up Mo in a 1-min period. The best strain was USDA 136, which had an Mo uptake activity of almost 3.0 pmol/min per mg of bacteroid (dry weight). In contrast, the poorest strain, USDA 62, had an Mo uptake activity of 0.35 pmol of Mo per min per mg of bacteroid. There were similarities in Mo uptake ability among most of the same serogroup members. The variability in Mo uptake rates between the best (USDA 136 and USDA 122) and poorest (USDA 62 and USDA 140) strains was attributed to their differing affinities for Mo. Double-reciprocal plots of velocity versus substrate indicated a Km for USDA 136 and USDA 122 of 0.045 and 0.054 microM, respectively, whereas strains USDA 62 and USDA 140 both exhibited an apparent Km for MoO42- of about 0.36 microM. The two strains with the higher-affinity Mo binding also accumulated four to five times as much Mo over a 30-min period as the other strains. Soybeans were grown in Mo-deficient and Mo-supplemented conditions after inoculation with the three top-ranking Mo uptake strains and the three poorest Mo uptake strains. Two separate greenhouse studies indicated that Mo supplementation significantly increased the N2 fixation activity of USDA 140 nodules; up to a 35% increase in specific nitrogen fixation activity of nodules due to Mo supplementation was observed. Strain USDA 62 nodule N2 fixation responded positively to Mo supplementation in one of the two experiments. The results indicate that MoO42- transport and, specifically, affinity for Mo by the bacteroid may ultimately affect symbiotic N2 fixation activity. Attempts to reactivate nitrogenase by adding molybdate to bacteroids from plants grown in Mo-deficient conditions were unsuccessful.

Biological Transport↗
PubMed1987

Differential medium for mixed cultures of alpha-hemolytic streptococci from blood.

Alpha-hemolytic streptococci (AHS) were isolated from blood cultures from 100 patients, and species were identified by the Ruoff and Kunz scheme. When isolates were inoculated onto sheep blood agar, all 100 cultures appeared to be pure, with identifications based on colonial morphology and Gram stain. When isolates were subcultured onto mitis salivarius agar (MSA), mixtures of two species of AHS were detected in 10 cultures from patients (10%). These mixed cultures would have been reported as pure cultures of Streptococcus milleri (six cultures), Streptococcus salivarius (three cultures), Streptococcus sanguis I (one culture), with identifications based on biochemical profiles. Cultures on MSA demonstrated S. milleri (six cultures), Streptococcus mitis (five cultures), S. salivarius (three cultures), S. sanguis I (one culture), and S. sanguis II (five cultures). The inability to separate AHS species by colony morphology on sheep blood agar demands that a differential medium such as MSA be routinely used for subculture. Failure to use such a medium may account for some of the confusing biochemical profiles associated with AHS species identification.

Blood↗
PubMed1987

AIDS: developing a primary health care task force.

As the number of people with AIDS increases, the number of people impacted by the AIDS crisis will also increase. Larger metropolitan areas have already responded to the crisis with various services (Deuchar, 1984); but the disease has yet to fully impact on smaller cities and towns. The formation of community service groups to cope with the AIDS crisis is a virtual necessity in health care preparation for persons with AIDS. The experience of the Fort Wayne AIDS Task Force reflects the potential of any community to utilize the existing resources in the gay and lesbian community, health and social service professions, and among family and friends of persons with AIDS. Consultation and resources are available through local and state boards of health, as well as local social service and health personnel currently dealing with the AIDS crisis.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Circadian variations in eleven radioimmunoassay variables in the serum of clinically healthy men.

Radioimmunoassay studies were conducted on 13 clinically healthy male subjects. Ten ranged in age between 23 and 44 years, two were age 51, and one was age 58. Blood samples were collected at 3-hr intervals over a period of 27 hr. Each serum sample was analyzed for the following hormones: insulin, gastrin, melatonin, prolactin, triiodothyronine (uptake), thyroid-stimulating hormone, triiodothyronine, thyroxine, luteinizing hormone, growth hormone, and follicle-stimulating hormone. Group data for each hormone were fitted to a 24-hr cosine curve. A statistically significant fit to this curve was evident in the six italicized variables. Those that did not yield a statistically significant fit frequently revealed a statistically significant variation along the 27-hr span. Chronogram and cosinor plots are presented.

Adult↗
PubMed1986

[14C]acrylonitrile: preparation via a stable tosylate intermediate and quantitative reaction with amine residues in collagen.

A simple, convenient synthetic procedure for [14C]acrylonitrile is described. Na14CN is used as the radioactive starting material. Small (milligram) amounts are converted to 3-[14C]Hydroxypropionitrile by a substitution reaction with 2-chloroethanol. 3-[14C]Hydroxypropionitrile is then tosylated, and the specific activity of this intermediate product is easily determined using its uv extinction coefficient and scintillation counting. [14C]Acrylonitrile is obtained rapidly on distillation by heating the tosylate in the presence of a high boiling tertiary amine base catalyst. The tosylate intermediate can be stored, in contrast to radioactive acrylonitrile, which is unstable. The reaction of acrylonitrile with lysine, hydroxylysine, and histidine residues in human Achilles tendon collagen, as well as chromatographic separation and identification of the carboxyethyl derivatives of these amino acids, is also described.

Acrylonitrile↗
PubMed1986

Effect of medium and cultivation conditions on comparisons between latex agglutination and culture detection of group A streptococci.

In the laboratory diagnosis of pharyngitis, results from latex agglutination tests (LAT) performed directly on throat swabs are often compared with the isolation of group A beta-hemolytic streptococci (GABHS) from simultaneously obtained swabs cultivated on a variety of media under different atmospheric conditions. In this study, results of an LAT, Directigen, were compared with those of two different media: sheep blood agar (SBA) and group A selective strep agar (ssA). Specimens inoculated on SBA were incubated in three different atmospheres: air, 3 to 5% CO2, and anaerobically. Those inoculated on ssA were incubated in 3 to 5% CO2 only. Isolation of GABHS was confirmed by coagglutination. The standard for true positivity was the isolation of GABHS from at least one of the simultaneous cultures. Comparisons were made with samples from 693 adult patients. GABHS was isolated on at least one of the three cultures in 143 patients, demonstrating an isolation rate of 20.6%. LAT exhibited a sensitivity of 95.1%. SBA incubated in air, in CO2, or anaerobically had sensitivities of 86.2, 85.9, and 93.7%, respectively. The ssA detected 99.3% of the positive specimens. Single SBA culture proved to be inferior to LAT and therefore was a poor standard for measuring LAT performance. Single ssA cultures demonstrated the greatest sensitivity in GABHS detection and therefore could serve as a standard for measuring LAT performance.

Aerobiosis↗
PubMed1985

Diffusion of labeled water and lipophilic solutes in the lung.

A perfused, in situ rabbit lung preparation was used to study the diffusion of tritiated water and labeled lipophilic solutes from the airways into the pulmonary vasculature. Following instillation into the airways, initial concentrations of labeled ethanol and butanol in the left atrial outflow usually exceeded those of 3H2O when the lungs were perfused at 37 degrees. In contrast, initial concentrations of [14C]acetone equaled 3H2O concentrations, and those of [14C]antipyrine were below 3H2O concentrations. Increasing the rate of perfusion increased concentrations of the labeled butanol and acetone but decreased that of antipyrine relative to 3H2O. This suggests that the tissues separating the gaseous and vascular compartments of the lung are more permeable to 3H2O than to antipyrine but less permeable to 3H2O than to the alcohols and acetone. Cooling slowed permeation of ethanol and antipyrine relative to 3H2O but seemed to slow diffusion of butanol less than that of 3H2O. These differences cannot be related to movement in the aqueous phase and suggest that cooling slows solute diffusion through lipid membranes. This phenomenon appears to be related to the activation energy of each molecule between the aqueous and lipid phases rather than a phase change in the membrane. 3H2O seems to diffuse through aqueous regions of the air-perfusate barrier.

Acetone↗
PubMed1985

Paramagnetic probes of multicomponent electron-transfer systems.

Electron-transfer systems associated with steroid hormone production in the adrenals and with photosynthetic NADP+ reduction in the chloroplast share some important features. Complexes between components in both systems affect the exposure of prosthetic groups to water-soluble paramagnetic groups. The sensitivity of the components to probes of different charges suggests that electrostatic interactions are important in complex formation. Haem plane orientation in cytochrome P-450 of the adrenal system is parallel to the membrane plane in both native and reconstituted systems.

Adrenal Glands↗
PubMed1978

The role of cell wall carbohydrates in binding of microorganisms to mouse peritoneal exudate macrophages.

The recognition by macrophages of unopsonized bacteria was studied, employing a binding assay, performed at 4 degrees C. Various Gram positive and Gram negative bacteria were shown to bind to glass-adherent mouse peritoneal exudate cells under these conditions, Str. pneumoniae being the only exception. The binding could be inhibited by pretreatment of the macrophage monolayers with various monosaccharides. The role of particular components of the bacterial cell wall in binding was examined further using different strains of K. aerogenes and S. typhimurium with a known cell wall composition and mutant strains deficient in certain sugars. The ability of a particular constituent to inhibit binding was found to correlate closely with its presence in the bacterial cell wall. It is concluded, that this form of binding, mediated by cell wall carbohydrates represents a primitive recognition mechanism enabling phagocytes to bind microorganisms.

Animals↗
PubMed1977

Comparison of the lipid-lowering effect of clofibrate, and of clofibrate plus beta-pyridylcarbinol.

Forty-eight patients under 65 years were included in a double blind study comparing the lipid-lowering effect of clofibrate with that of beta-pyridylcarbinol combined with clofibrate. Over 4 months there was no significant difference in the lipid-lowering effect of either regime. A mean reduction of triglyceride of approximately 30% and of cholesterol of 18% was observed. Both drugs caused significantly greater reductions than placebo. No serious side-effects were noted.

Analysis of Variance↗
PubMed1976

Proxemics, locus of control, anxiety, and type of movement in emotionally disturbed and normal boys.

In order to determine the interpersonal distancing requirements for emotionally disturbed and normal children and in order to investigate the relationship of locus of control and anxiety to interpersonal space, 20 emotionally disturbed and 20 normal boys were randomly required to approach an object person and to let the object person approach them until they felt uncomfortable. Results indicated that emotionally disturbed boys required more space than normals; that subjects would approach closer than they would allow the object person to approach them; and that externals required more space than internals. There were no significant differences between high and low anxious subjects, nor between emotionally disturbed children diagnostically classified as overanxious reaction and those with other diagnosis. Finally, neither anxiety nor locus of control explained the significant normal-emotionally disturbed differences in space requirements. Theoretical and practical implications were discussed as well as the relationship between the present and previous research.

Affective Symptoms↗