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Biomedical subjects

J Love

Publications and source records attributed to J Love.

At least 91 records · Page 5Linked to original sources
PubMed1984

Spontaneous Nif- mutants of Rhodopseudomonas capsulata.

Revertible, spontaneous Nif- mutants of Rhodopseudomonas capsulata have been shown to accumulate in cultures growing photosynthetically with an amino acid as the nitrogen source such that H2 is maximally produced. The majority of such strains carry mutations which are clustered in a short region of the chromosome, probably representing one or two genes. Because this cluster includes temperature-sensitive mutations, it is also likely that it identifies the structural gene of a polypeptide. The phenotypic characterization of these spontaneous mutants showed (i) an inability to grow with N2 as the nitrogen source, no measurable nitrogenase activity, a reduction or absence of the three polypeptides of the MoFe and Fe proteins of the nitrogenase complex, a faster growth rate on glutamate as the nitrogen source under saturating light, and frequently a small increase in glutamine synthetase activity relative to that of the wild type when grown with glutamate as the nitrogen source. Alterations in other ammonium-assimilatory enzyme activities were not observed. Taken together, these properties suggest that the mutations have affected a regulatory protein necessary for nitrogen fixation.

Alanine Dehydrogenase↗
PubMed1984

Metabolism and binding of cyclophosphamide and its metabolite acrolein to rat hepatic microsomal cytochrome P-450.

The hepatic cytochrome P-450-mediated metabolism and metabolic activation of [chloroethyl-3H]cyclophosphamide [( chloroethyl-3H]CP) and [4-14C]cyclophosphamide [( 4-14C]CP) were investigated in vitro in the reconstituted system containing cytochrome P-450 isolated from phenobarbital-treated rats. In addition, hepatic microsomal binding and the hepatic microsome-mediated metabolism of [14C]acrolein, a metabolite of [4-14C]CP, were also investigated. The metabolism of [chloroethyl-3H]CP and [4-14C]CP to polar metabolites was found to depend on the presence of NADPH and showed concentration dependence with respect to cytochrome P-450 and NADPH:cytochrome P-450 reductase. Km and Vmax values were essentially similar (Km, 0.44 and 0.42 mM; Vmax, 4.8 and 7.0 nmol of polar metabolites formed/min/nmol of cytochrome P-450 for [4-14C]CP and [chloroethyl-3H]CP, respectively). The patterns of inhibition by microsomal mixed-function oxidase inhibitors, anti-cytochrome P-450 antibody, and heat denaturation of the cytochrome P-450 were essentially similar, with subtle differences between [4-14C]CP and [chloroethyl-3H]CP metabolism. The order of inhibition by various mixed-function oxidase inhibitors was SKF greater than alpha- and beta-naphthoflavones greater than metyrapone. The in vitro metabolic activation of CP in the reconstituted system demonstrated predominant binding of [chloroethyl-3H]CP to nucleic acids and almost exclusive binding of [4-14C]CP to proteins. Gel electrophoresis-fluorography of the proteins in the reconstituted system treated with [4-14C]CP demonstrated localization of the 14C label in the cytochrome P-450 region. To examine this association further, hepatic microsomes were modified with [14C]acrolein in the presence and the absence of NADPH. The results confirmed covalent association between [14C]acrolein and cytochrome P-450 in the microsomes and also demonstrated further metabolism of [14C]acrolein, apparently to an epoxide, which is capable of binding covalently to proteins. The results of these investigations not only confirm the significance of primary metabolism but also emphasize the potential role of the secondary metabolism of cyclophosphamide in some of its toxic manifestations.

Acrolein↗
PubMed1983

High pressure liquid chromatographic separation of multiple forms of cytochrome P-450.

The major form of cytochrome P-450 isolated and purified from the hepatic microsomes of phenobarbital pretreated rats by sequential chromatography on n-octylamino-Sepharose 4B and DEAE-cellulose columns was found to be homogeneous by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. However, this cytochrome P-450 was resolved into three bands by high pressure liquid chromatography on an Anpac ion-exchange column. High pressure liquid chromatography isolated forms had similar molecular weights of 55,000 with lambda max of the CO-reduced difference spectrum at 450 nm and were found to be in the low spin state. The results demonstrate the effectiveness of high pressure liquid chromatography in the resolution of cytochrome P-450s of similar molecular weights but different net charges.

Animals↗
PubMed1983

Rheumatoid vasculitis: diagnostic and therapeutic decisions.

Rheumatoid vasculitis is an uncommon but potentially catastrophic complication of RA. There are few extensive experiences recorded in the current literature and there is no consensus regarding the clinical features, laboratory findings, histologic pattern, prognosis, or appropriate management of this syndrome. We therefore surveyed 1,947 North American ARA members for their perceptions of rheumatoid vasculitis. Four hundred twenty-eight surveys were returned, of which 290 were suitable for analysis. The majority of respondents were within 10 years of fellowships and were evenly distributed among private practice, and part-time and full-time academic positions. The respondents saw 15-50 rheumatoid arthritis (RA) patients weekly and less than five RA vasculitis patients annually. The majority correctly diagnosed two actual and complex case histories from patients with and without autopsy-proven vasculitis. Respondents associated the following features most strongly with rheumatoid vasculitis - mononeuritis multiplex, digital gangrene, digital ischemic lesions, nailfold ischemic lesions, non-healing leg ulcers, palpable purpura, fingertip nodules, sensory neuropathy, scleromalacia perforans, high titer rheumatoid factor, positive visceral angiography, cryoglobulinemia, hypocomplementemia, circulating immune complexes, and histologic necrotizing vasculitis or vascular transmural neutrophilia. Digital lesions or sensory neuropathy alone were not viewed as portending an ominous prognosis by most respondents and would have been treated with nonsteroidal anti-inflammatory drugs, antimalarials, gold salts, or D-penicillamine. Other clinical manifestations considered as reflecting rheumatoid vasculitis (gangrene, mononeuritis multiplex, ulcers) were thought to worsen prognosis and would have been managed more often with corticosteroids, D-penicillamine, cytotoxic agents or plasmapheresis. Rheumatoid vasculitis is viewed as a heterogeneous group of syndromes with varying clinical and histopathologic features,which have different prognostic implications, and therefore should be managed differently. While these dta do not substitute for an extensive recorded series of patients, they provide useful information about community perceptions of an uncommon but difficult clinical problem. They identify the need for additional data to examine the validity of these attitudes.

Arthritis, Rheumatoid↗
PubMed1983

Intestinal pseudo-obstruction as the presenting manifestation of small-cell carcinoma of the lung. A paraneoplastic neuropathy of the gastrointestinal tract.

A 58-year-old woman who had presented with intestinal pseudo-obstruction died 9 months later from rapidly progressive neurologic symptoms and autonomic insufficiency. Her gastric emptying had been markedly delayed and transit of markers had been slowed throughout the small bowel. A 5-hour manometric recording of the antrum and duodenum had shown absence of the normal interdigestive motor complex, which was replaced by irregular contractile activity of reduced amplitude. A small-cell carcinoma of the lung was found at autopsy. Pathologic study of the gut showed widespread degeneration of the myenteric plexus, which was infiltrated by plasma cells and lymphocytes and contained significantly reduced numbers of neurons. The extra-intestinal nervous system had neuronal loss and lymphocytic infiltrates in dorsal root ganglia. Thus, a gastrointestinal neuropathy causing intestinal pseudo-obstruction may be the presenting manifestation of a paraneoplastic syndrome associated with small-cell carcinoma.

Autonomic Nervous System Diseases↗
PubMed1983

Assessment of the diet of patients with rheumatoid arthritis and osteoarthritis.

There have been many and divergent thoughts expressed both in the scientific and in the lay literature regarding diets for patients with arthritis (1-8). However, few experimental observations pertain to either the nutritional status of arthritis patients or the clinical value of putative nutritional therapies (1-8). Until such time as the notion that dietary manipulation can alleviate particular symptoms for selected patients is proved, it is prudent to advise patients to maintain sound nutritional practices in accordance with contemporary standards (4-8, 13-16). Our data indicate that many arthritis patients are at least marginally inadequate in selected nutrients, some of which (vitamin E and zinc) might relate to immunologic events important in perpetuating the disease. These observations provide a basis for nutritional counseling of arthritis patients.

Adolescent↗
PubMed1981

Alteration of the action potential of tissue cultured neuronal cells by growth in the presence of a polyunsaturated fatty acid.

The effects of alterations in membrane phospholipid fatty acid composition on the excitability of neuroblastoma X glioma hybrid cells, clone NG108-15, were examined using intracellular recording techniques. Cells were grown in the presence of arachidonate (20:4) added to the culture medium as a complex with bovine serum albumin. Exposure of the cells to 20:4 for 3-21 days produced a 40% decrease in the maximum rate of rise of the action potential (dV/dt) with a small change in its amplitude. The resting membrane potential and passive properties of the cells were unaffected. An effect of 20:4 was not observed until 24 hr after treatment and increased over the next 2 days. The phospholipid content of 20:4 and its metabolite 22:4 increased from 6.9% to 25.3% of total fatty acids during approximately the same time span. It is concluded that the action potential dV/dt can be altered by changes in membrane lipid composition.

Action Potentials↗