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K M Shaw

Publications and source records attributed to K M Shaw.

At least 55 records · Page 3Linked to original sources
PubMed1986

Assessment of immunochemical methods for determining low concentrations of albumin in urine.

Four immunochemical methods (radioimmunoassay, RIA; radial immunodiffusion, RID; immunoturbidimetry, IT; enzyme-linked immunosorbent assay, ELISA) for measuring urinary albumin at low concentrations were assessed for their assay characteristics and practicability. Precision and accuracy were comparable between the methods when studied individually. We made a method comparison, with RIA as reference, using urine samples from diabetic patients with albumin concentrations ranging from 1 to 120 mg/L. There was no significant systematic difference between RID and RIA, but IT and ELISA gave consistently lower values than RIA, the mean differences being 1.8 (p less than 0.01) and 9.7 mg/L (p less than 0.001), respectively. Random error, compared with that for RIA, was in increasing order: RID (residual SD = 3.8 mg/L); IT (4.3 mg/L); ELISA (7.3 mg/L). The difference between the methods increased with the albumin concentration. Operational cost was highest with IT, lowest with RIA. Capital cost was highest with RIA and lowest with RID, which required most technical skill. ELISA had intermediate overall costs.

Albuminuria↗
PubMed1985

Methanogenesis and the K+ transport system are activated by divalent cations in ammonia-treated cells of Methanospirillum hungatei.

We describe a K+ transport system in Methanospirillum hungatei cells depleted of cytoplasmic K+ via an ammonia/K+ exchange reaction (Sprott, G. D., Shaw, K. M., and Jarrell, K. F. (1984) J. Biol. Chem. 259, 12602-12608). Ammonia-treated cells contained low concentrations of ATP and were unable to make CH4 or to transport 86Rb+. All of these properties were restored by CaCl2, MgCl2, or MnCl2, and not by CoCl2 or NiCl2. The Rb+ transport system had a Km of 0.42 and Vmax of 29 nmol/min X mg; K+ inhibited competitively. Both H2 and CO2 were required for appreciable transport, whereas air, valinomycin, or nigericin were potent inhibitors. The influx of Rb+ was electrogenic and associated with proton efflux, producing a delta pH (alkaline inside) in acidic media. In the absence of K+ (or Rb+), the activation of CH4 synthesis by Mg2+ produced little change in the cytoplasmic pH, showing that methanogenesis did not elicit a net efflux of protons. The pH optimum for transport was in the range 6.0-7.3 where the transmembrane pH gradient would contribute minimally to the proton motive force. Protonophores at pH 6.3 caused a partial decline in CH4 synthesis and the ATP content and dramatically collapsed Rb+ transport. These and other inhibitor experiments, coupled with the fact that the Rb+ gradient was too large to be in equilibrium with the proton motive force alone, suggest a role for both ATP and the proton motive force in Rb+ transport. Also, a role for K+ in osmoregulation is indicated.

Ammonia↗
PubMed1985

Closure of the lower end of the esophagus following esophagectomy.

Carcinoma of the middle third of the esophagus remains a major technical challenge in surgery. A speedy and safe method for dealing with the lower esophageal stump is described. After mobilization, the lower esophagus is denuded of its muscular fibers; the remaining mucosal tube is ligated and invaginated into the cardia by a pursestring suture.

Cardia↗
PubMed1985

Home blood glucose monitoring in non-insulin-dependent diabetics: the effect of gliclazide on blood glucose and weight control, a multicentre trial.

The efficacy of the sulphonylurea gliclazide was assessed in 229 non-insulin-dependent diabetics attending U.K. outpatient diabetic clinics. Patients inadequately controlled by diet alone or oral hypoglycaemic agents used reflectance meters to monitor their blood glucose. After a 4-week run-in, in those whose control remained unsatisfactory, gliclazide was either added to diet, or given in place of existing drugs. Patients continued home-monitoring and were followed for 3 months. Gliclazide reduced mean random blood glucose in all groups, particularly those previously treated by diet alone or a first-generation sulphonylurea. The patients improved in their ability to measure glucose at home and within 2 months a good correlation with laboratory measurements was found. Mean body weight was reduced, particularly in obese and elderly subjects and those treated previously with sulphonylurea drugs. Side effects were mild and only two patients were withdrawn for this reason.

Blood Glucose↗
PubMed1984

Ammonia/potassium exchange in methanogenic bacteria.

Methanospirillum hungatei exposed to ammonia in a K+-free buffer lost up to 98% of the cytoplasmic K+ through an ammonia/K+ exchange reaction. The exchange was immediate, and occurred in cells poisoned by air or by other metabolic inhibitors. Additions of NH4OH or various NH+4 salts (or methylamine) were most effective in causing K+ depletion in media of alkaline pH, suggesting that NH3 was the chemical species crossing the membrane. In alkaline media, the exchange reaction resulted in a dissipation of the transmembrane pH gradient (inside acidic), but had only small effects on the membrane potential until concentrations of ammonia were used above those required to abolish the K+ gradient. Through the use of NH4Cl to vary the cytoplasmic pH at a constant acidic external pH, and NH4OH to abolish the transmembrane pH gradient at various alkaline external pH values, we conclude that methanogenesis is sensitive to both the pH of the cytoplasm and the medium. Methanogenesis in Msp. hungatei and Methanosarcina barkeri was inhibited dramatically at external pH values more acidic than 6.5 or more alkaline than 7.5. Dramatic K+ depletion in response to ammonia additions at pH 8.0 occurred with Ms. barkeri, another strain of Msp. hungatei, Escherichia coli, and Bacillus polymyxa. In several other methanogens, ammonia/potassium exchange was hardly detected.

Ammonia↗
PubMed1983

Isolation and chemical composition of the cytoplasmic membrane of the archaebacterium Methanospirillum hungatei.

The cytoplasmic membrane of Methanospirillum hungatei was isolated from osmotic lysates of spheroplasts, with yields of 7-8% of the cell dry weight. Cytoplasmic contamination was negligible, as judged by the removal of soluble enzymes. The cytoplasmic membrane consists of lipid (35-37%), primarily as a biphytanyldiglycerol tetraether glycolipid; protein (45-50%); and carbohydrate (10-12%). Ultra-thin sections showed that the trilaminar membrane formed vesicles with a maximum diameter of 0.4 microns. Protrusions of membrane projecting from the vesicles were seen often in negatively stained preparations. Fractionation of M. hungatei cells grown in the presence of [14C]mevalonic acid revealed that 90% of the phytanyl lipids were present in the cytoplasmic membrane band, with two minor bands accounting for the remainder of the label. Approximately 50% of the galactose, glucose, and mannose present in the cytoplasmic membrane was found in lipid extracts, while the remainder of these sugars and 98% of the rhamnose were present as nonlipid sugars. The cell sheath, isolated with a yield of 13% of the cell dry weight, contained the same sugars as the cytoplasmic membrane, but in very different proportions. Amino acid analysis of the membrane proteins showed that hydrophobic amino acid residues made up 37% of the total, neutral amino acids, 39%, basic, 8%, acidic, 16%, and that half-cysteine was present. Sodium dodecyl sulfate-polyacrylamide gel patterns of solubilized cytoplasmic membrane proteins revealed major bands at 195, 74.5, 44, 32, and 30 KDa. Significant amounts of nickel co-isolated with the cytoplasmic membrane, accounting for 0.16% of the membrane dry weight.

Carbohydrates↗
PubMed1981

Isolation and characterization of a FAD-dependent NADH diaphorase from Methanospirillum hungatei strain GP1.

Crude extracts of Methanospirillum hungatei strain GP1 contained NADH and NADPH diaphorase activities. After a 483-fold purification of the NADH diaphorase the enzyme was further separated from contaminating proteins by polyacrylamide disc gel electrophoresis. Two distinct activity bands were extracted from the acrylamide, each one having oxygen, 2,6-dichlorophenolindophenol, and cytochrome c linked activities. In these preparations NADPH could not replace NADH as electron donor. During the initial purification steps all activity was lost due to the removal of a readily released cofactor. Enzyme activity was restored by either FAD or a FAD fraction isolated from M. hungatei. Oxidase activity exhibited a broad pH optimum from 7.0 to 8.5 and apparent Km values of 26 microM for NADH and 0.2 microM for FAD. Superoxide anion, formed in the presence of oxygen, accounted for all of the NADH consumed in the reaction. The molecular weight of the diaphorase was about 117 500 by sodium dodecyl sulfate gel electrophoresis. Sulfhydryl reagents and chelating agents were inhibitory. Inactivation, which occurred during storage in phosphate buffer at 4 degrees C, was delayed by dithiothreitol. The isolated NADH diaphorase lacked NADPH:NAD transhydrogenase and NAD reductase activities.

Dihydrolipoamide Dehydrogenase↗
PubMed1980

The impact of treatment with levodopa on Parkinson's disease.

The progress of 178 patients with Parkinson's disease who began treatment with levodopa between November 1969 and December 1972 is reviewed after six years. One hundred and twenty-five patients showed an initial improvement of their individual total disability scores exceeding 25 per cent, but after six years of sustained treatment only 37 patients still obtained similar benefit. By 1978 only five patients had maintained their initial improvement compared to 69 patients after two years therapy; however, 47 patients were still better than before treatment. The overall mortality ratio--the ratio of observed to expected death rate--for all the patients was 1.45:1. In those patients who unable to tolerate levodopa for longer than two years the ratio was 2.38:1; in those who were able to tolerate sustained medication, life expectancy was normal (ratio of 0.91:1 for males and 1.14:1 for females). Involuntary movements were the commonest complication of treatment. Three main types were distinguished. Peak dose dyskinesias, beginning 20 to 90 minutes after an oral dose and most severe midway through the inter-dose period, affected 80 per cent of patients. Early morning and end-of-dose dystonia occurred in 20 per cent of patients and biphasic dyskinesia--two distinct episodes of involuntary movements within each inter-dose period--was the least common pattern affecting 3 per cent of patients. Involuntary movements increased in frequency and severity as treatment continued. End-of-dose deterioration ('wearing-off' effect of individual doses) occurred in 65 per cent of patients: unpredictable oscillations in motor performance (the 'on-off' phenomenon) unrelated to the time and dosage of levodopa, occurred in 10 per cent. Psychiatric side effects included toxic confusional states, visual pseudohallucinations and paranoid psychoses and constituted the most frequent reason for stopping medication. Forty (22 per cent) of the patients had suffered severe depression before the onset of disease and levodopa had no sustained antidepressant effect in this group. After six years of treatment with levodopa, 32 per cent of the patients had unequivocal dementia.

Dyskinesia, Drug-Induced↗
PubMed1979

Lobectomy with sleeve resection of the bronchus for malignant disease of the lung and the influence of the suture material used for the bronchial repair.

A series of 100 consecutive cases of lobectomy combined with sleeve resection of the bronchus for malignant disease of the lung is presented. In 13 of these cases a sleeve resection of the appropriate pulmonary artery was also carried out. An operative mortality of 8% was encountered and a crude 5-year survival of 40% was achieved. A comparison of absorbable and non-absorbable suture materials for the bronchial anastomosis indicated that the absorbable suture, Polyglycolic Acid (Dexon), minimized the morbidity from complications at the bronchial anastomosis.

Bronchi↗
PubMed1979

Prolonged survival with adrenal cortical carcinoma.

Recurrence of adrenal cortical carcinoma 22 years after first presentation is reported in a 54-year-old woman with Cushing's syndrome. This tumour is normally associated with poor prognosis and prolonged survival is rare. Although the patient had remained well with apparent 'cure' in the intervening years, it is suggested that hormonal changes related to the menopause and the development of primary hypoadrenalism stimulated recurrence of malignant activity and return of Cushingoid features.

Adrenal Cortex Neoplasms↗