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J C Mason

Publications and source records attributed to J C Mason.

At least 55 records · Page 3Linked to original sources
PubMed1992

Giant cell arteritis.

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Drug Administration Schedule↗
PubMed1992

An integrated approach to studying regulation of production of the antibiotic methylenomycin by Streptomyces coelicolor A3(2).

A physiological and molecular biological study was made of the control of methylenomycin biosynthesis by Streptomyces coelicolor A3(2). A simple and reliable assay for this antibiotic was developed. Conditions that permit the synthesis of methylenomycin by S. coelicolor cultures grown in defined medium were elucidated: a readily assimilated carbon and nitrogen source is required. Under these conditions methylenomycin is produced late in the growth phase, at the time of transition from exponential to linear growth. Provided that the phosphate concentration in the medium is kept high, there is synthesis of methylenomycin but not of the other secondary metabolites that this strain can produce. These conditions were used to study the transcription of the methylenomycin gene cluster during the transition from primary to secondary metabolism. The biosynthetic genes of at least one of the mmy transcription units appear to be transcribed before the mmr resistance determinant. The possibility that methylenomycin induces the transcription of mmr is discussed.

Acetates↗
PubMed1992

Renal disease associated with circulating antineutrophil cytoplasm activity.

We report our detailed observations on a group of 30 consecutive patients with renal disease, histologically demonstrated glomerulitis or necrotizing vasculitis, and circulating antineutrophil cytoplasm activity (ANCA). The annual incidence of ANCA-related renal disease was seven cases per million population. The sensitivity of serum ANCA for histologically proved glomerular vasculitis was 79 per cent, with a specificity of 87 per cent. Most patients responded to treatment with cyclophosphamide and steroids but complications of therapy occurred in just over half the patients and were serious in 20 per cent. Actuarial survival at 1 year was 60 per cent. Age and dialysis requirement did not influence outcome and the only identified adverse prognostic factor was hypoxic lung disease. We conclude that the association of ANCA with renal disease is not rare and that positive serology accurately identifies a homogeneous group of patients with similar clinical, histological, and prognostic features. Separation of these patients into those with the disease entities of Wegener's granulomatosis and microscopic polyarteritis is not straightforward on clinical and histological criteria, and such a distinction does not yield useful therapeutic or prognostic information. Simple urinalysis should always be carried out in patients with undiagnosed systemic illness in order to identify renal disease. ANCA-related renal disease can be treated successfully with cyclophosphamide and steroids and elderly patients should not be excluded from treatment, including dialysis if necessary. The ANCA test is simple and quick to perform and, in the appropriate clinical setting, accurately identifies patients who may benefit from immunosuppressive treatment before a histological diagnosis can be established.

Adult↗
PubMed1988

Brain abscess from chronic odontogenic cause: report of case.

A case of a chronic odontogenic abscess that probably precipitated a frontopatrietal brain abscess by hematogenous spread has been presented. A thorough examination of the patient showed no other source of infection. Peptostreptococcus sp was found as the common pathogen despite 6 days of broad-spectrum antibiotic therapy. This case emphasizes the important role of dentistry in medical diagnosis and treatment implemented in the hospital setting.

Brain Abscess↗
PubMed1985

Urolithiasis and race: another viewpoint.

We describe 193 consecutive individuals with documented urolithiasis in a military population. In contrast to other reports, the prevalence of stone disease was nearly identical in white-and black patients. This unique black population refutes the concept that urinary calculi are rare in blacks.

Black or African American↗
PubMed1985

Sodium pump activity in thymocytes of rats with Goldblatt hypertension.

Sodium transport has been studied in thymocytes of one-kidney, one-clip (1K, 1C) and two-kidney, one-clip (2K, 1C) models of hypertension in the rat. No differences of intracellular sodium or sodium transport could be demonstrated in either model when compared with sham-operated controls. The experiments provide no evidence to support the concept that an inhibitor of sodium transport is associated with the development of hypertension in the one-kidney, one-clip rat. A previously unrecognized effect of incubation time and cell density on thymocyte sodium metabolism is reported.

Animals↗
PubMed1985

Identification of distinct receptor complexes that account for high-and low-affinity glucagon binding to hepatic plasma membranes.

We have analyzed ligand-receptor complexes resulting from (i) the incubation of canine hepatic plasma membranes with [125I]iodoglucagon and (ii) subsequent gentle solubilization of receptor-bound ligand with digitonin. The complexes (molecular weight approximately equal to 500,000) retain the radiolabeled ligand during gel filtration and subsequent manipulation at 4 degrees C in the absence of covalent crosslinking. Affinity chromatography of the glucagon-receptor complexes on columns of wheat germ lectin linked to agarose resulted in two fractions, one of which was not bound by the column and the other of which was specifically eluted by N-acetylglucosamine. The presence of GTP during the incubation of plasma membranes with [125I]iodoglucagon caused about a 50% decrease in total ligand binding but affected only the ligand-receptor complexes that bound to wheat germ lectin. Moreover, it was found that the proportion of the two forms of ligand-receptor complexes identified by chromatography on wheat germ lectin depended on the degree of saturation of the membrane receptor. Thus, both the inhibition by glucagon of radiolabeled glucagon binding to membranes and the concomitantly decreased extent of association of the radiolabeled ligand with solubilized receptor complexes could be modeled in terms of two noninteracting receptor populations (having dissociation constants of about 0.35 and 4.94 X 10(-9) M). We conclude that (i) glucagon-receptor complexes formed on canine hepatic plasma membranes exist in two forms that differ after solubilization by digitonin in their avidities for wheat germ lectin, (ii) the high-and low-affinity binding of glucagon characteristic of hepatic plasma membranes arises from distinct receptor populations that probably differ in glycosylation, and (iii) the effect of GTP to decrease binding of glucagon to membranes arises from interactions of the nucleotide with the receptor complex that binds to wheat germ lectin.

Animals↗
PubMed1985

Characterisation of non-histone nuclear proteins cross reactive with purified rheumatoid factors.

In order to examine the interactions between isolated rheumatoid factors (RFs) and cell nuclear antigens we have prepared 10 RFs by affinity chromatography against IgG coupled to Sepharose. Of these, seven cross reacted with cell nuclei on indirect immunofluorescence. The nuclear antigen appeared to be DNA histones by indirect immunofluorescence on rat liver, though on immunoblotting the rheumatoid factors also reacted with three non-histone polypeptides which were identified in the soluble fraction of nuclear extracts. We were unable to show any relationship between these polypeptides and rheumatoid arthritis nuclear antigen. These reactions represent a hitherto unrecognised phenomenon, which extends the range of antigens recognised by rheumatoid factors. We suggest that the immunopathogenic significance of RFs may not be restricted to their reactivity with IgG, and that non-histone nuclear proteins merit further investigation.

Antigens, Nuclear↗
PubMed1985

Patient-predicted length of stay and diagnosis-related-group reimbursement.

Comparing patient-predicted to actual length of stay of 127 general psychiatric inpatients, the authors found excessive length of stay among demented geriatric patients and young patients with personality disorders. They recommend altering treatment provision to reduce stays to diagnosis-related-group standards.

Adult↗
PubMed1983

Medical illness in chronic psychiatric outpatients.

A careful physical and laboratory evaluation of 144 chronic psychiatric outpatients revealed medical illnesses in 26%. Chart review indicated that 13% of the patients had illnesses that were previously undetected and that 13% of the patients received some form of new treatment because of the evaluation. The majority of the illnesses did not appear to have directly caused or exacerbated psychiatric symptoms. Because medical illnesses were relatively common in this population, psychiatrists caring for chronic psychiatric outpatients often need to assume some of the health care referral and coordinating functions typically associated with a primary care physician.

Adult↗