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Biomedical subjects

M G Smith

Publications and source records attributed to M G Smith.

At least 73 records · Page 4Linked to original sources
PubMed1982

Axonal transport of noradrenaline and noradrenergic transmission in rats with streptozotocin-induced diabetes.

The accumulation of noradrenaline in constricted sciatic nerves was measured in 6 month diabetic rats (streptozotocin 35 mg/kg) and 4 day diabetic rats (streptozotocin 70 mg/kg) together with two groups of age-matched control animals. There was no alteration in the amount of noradrenaline accumulated in the nerves of the diabetic animals when compared with the controls. The vasa deferentia of the long-term diabetic animals showed an impaired response to stimulation of their noradrenergic nerves and a hypersensitivity to exogenous noradrenaline. These vasa were not wasted and showed a normal contractility in response to potassium chloride. Vasa deferentia from the short-term diabetic rats showed no abnormalities of function. Vasa deferentia from all groups of rats were also examined at the ultrastructural level. Specimens from all the chronically diabetic animals contained many abnormal nerve terminals. These lesions were not seen in vasa from the short-term diabetic rats. Taken together these findings indicate that rats with chronic streptozotocin-induced diabetes exhibit pathological changes in the noradrenergic nerves supplying the vas deferens. These animals do not, however, show an impairment of the axonal transport of noradrenaline.

Animals↗
PubMed1982

Characterization of the Formation and Distribution of Photosynthetic Products by Sedum praealtum Chloroplasts.

Photoassimilation of (14)CO(2) by intact chloroplasts from the Crassulacean acid metabolism plant Sedum praealtum was investigated. The main water-soluble, photosynthetic products were dihydroxyacetone phosphate (DHAP), glycerate 3-phosphate (PGA), and a neutral saccharide fraction. Only a minor amount of glycolate was produced. A portion of neutral saccharide synthesis was shown to result from extrachloroplastic contamination, and the nature of this contamination was investigated with light and electron microscopy. The amount of photoassimilated carbon partitioned into starch increased at both very low and high concentrations of orthophosphate. High concentrations of exogenous PGA also stimulated starch synthesis.DHAP and PGA were the preferred forms of carbon exported to the medium, although indirect evidence suported hexose monophosphate export. The export of PGA and DHAP to the medium was stimulated by high exogenous orthophosphate, but depletion of chloroplastic reductive pentose phosphate intermediates did not occur. As a result only a relatively small inhibition in the rate of CO(2) assimilation occurred.The rate of photoassimilation was stimulated by exogenous PGA, ribose 5-phosphate, fructose 1,6-bisphosphate, fructose 6-phosphate, and glucose 6-phosphate. Inhibition occurred with phosphoenolpyruvate and high concentrations of PGA and ribose 5-phosphate. PGA inhibition did not result from depletion of chloroplastic orthophosphate or from inhibition of ribulose 1,5-bisphosphate carboxylase. Exogenous PGA and phosphoenolpyruvate were shown to interact with the orthophosphate translocator.

Journal Article↗
PubMed1982

Aerobic catabolism of bile acids.

Seventy-eight stable cultures obtained by enrichment on media containing ox bile or a single bile acid were able to utilize one or more bile acids, as well as components of ox bile, as primary carbon sources for growth. All isolates were obligate aerobes, and most (70) were typical (48) or atypical (22) Pseudomonas strains, the remainder (8) being gram-positive actinomycetes. Of six Pseudomonas isolates selected for further study, five produced predominantly acidic catabolites after growth on glycocholic acid, but the sixth, Pseudomonas sp. ATCC 31752, accumulated as the principal product a neutral steroid catabolite. Optimum growth of Pseudomonas sp. ATCC 31752 on ox bile occurred at pH 7 to 8 and from 25 to 30 degrees C. No additional nutrients were required to sustain good growth, but growth was stimulated by the addition of ammonium sulfate and yeast extract. Good growth was obtained with a bile solids content of 40 g/liter in shaken flasks. A near-theoretical yield of neutral steroid catabolites, comprising a major (greater than 50%) and three minor products, was obtained from fermentor growth of ATCC 31752 in 6.7 g of ox bile solids per liter. The possible commercial exploitation of these findings to produce steroid drug intermediates for the pharmaceutical industry is discussed.

Aerobiosis↗
PubMed1982

A simple disc technique for the presumptive identification of Legionella pneumophila.

A method is described for the presumptive identification of Legionella pneumophila by the formation of satellite colonies around filter paper discs impregnated with ferric pyrophosphate and L-cysteine hydrochloride on a deficient basal medium. This technique simplifies the differentiation of picked colonies of L pneumophila from other organisms in mixed cultures from environmental and contaminated clinical samples.

Bacteriological Techniques↗
PubMed1981

Serum "prealbumin" as an index of liver function in human hepatobiliary disease.

Serum prealbumin concentrations have been studied, by a quantitative immunological procedure, in patients with secondary carcinoma of the liver, chronic active hepatitis, alcoholic hepatitis, cryptogenic cirrhosis, obstructive jaundice, inflammatory bowel disease, and myocardial infarction. The results showed that prealbumin concentration is significantly decreased when liver function is impaired. In diseases not associated with liver damage the concentrations of prealbumin were within the normal range. The advantage of this biochemical procedure is that serum prealbumin concentration is a true index of liver function, whereas serum enzyme activities signify only the degree of hepatocellular damage, which may not always quantitatively reflect liver function. Determination of serum prealbumin is therefore valuable in the diagnosis of liver disease and in the monitoring of treatment.

Biliary Tract Diseases↗
PubMed1981

Investigation and control of an outbreaks of legionnaires' disease in a district general hospital.

Between December, 1979, and July, 1980, 12 cases of legionnaires' disease were recognised in a district general hospital. 11 of the patients probably acquired their infection within the hospital. Epidemiological and environmental studies indicated that the plumbing system and possibly also the air-conditioning cooling-tower exhaust in the new building of the hospital were the sources of infection. Chlorination of the cold-water supply and raising the hot-water temperature appeared to terminate the outbreak.

Adult↗
PubMed1981

An Addisonian crisis complicating anaesthesia.

A patient with Addison's disease required surgery have attempted suicide, by cutting his throat and wrist. He was also in an acute adrenal crisis, as a result of deliberately omitting his replacement steroid therapy. Urgent surgery was indicated and therefore anaesthesia was undertaken before the patient's adrenal crisis was fully controlled. The anaesthetic management is described.

Addison Disease↗
PubMed1981

Marathon performance in relation to maximal aerobic power and training indices.

The purpose of this study was to examine the relationship of marathon performance time (MPT) with maximal aerobic power (VO2max), body composition, and training factors recorded for 9 wk prior to a race. Fifty males, 21 to 61 years of age (mean = 36 yr) with a mean weight of 69.6 kg, kept daily exercise records which included the distance and time run for each workout. VO2max ranged from 52.7 to 88.6 ml x kg-1 x min-1; total km for the 9 wk period ranged from 372 to 1260; km per workout ranged from 6.1 to 20.6; total workout days ranged from 28 to 61; and MPT ranged from 139 to 298 min. MPT was inversely related to VO2max (r = -0.63), total km (r = -0.67), average km per workout (r = -0.64), and total workout days (r = -0.62). MPT was slightly correlated with body weight (r = 0.41) and the sigma 7 skinfolds (r = 0.41). For a group of runners which includes both novice and experienced marathoners, MPT may be predicted (R2 = 0.71) by the following equation: MPT (min) = 525.9 + 7.09 (km x workout-1) -0.45 workout speed, m x min-1) -0.17 (total km for 9 wk) -2.01 (VO2max, ml x kg-1 x min-1) -1.24 (age, yr). These findings suggest that a high maximal aerobic power, low body mass, daily workouts, and training runs of long duration and distance contribute to better performance times in the marathon.

Adult↗
PubMed1980

Prealbumin as an index of liver function after acute paracetamol poisoning.

Liver damage in a woman who had taken an overdose of paracetamol and dextropropoxyphene was assessed by monitoring serum prealbumin concentrations and by routine plasma enzyme determinations. The plasma aspartate aminotransferase returned to normal levels after 3 days, alkaline phosphatase was slow to show increases in activity, and serum albumin concentration was in the normal range throughout. Prothrombin-time, although initially very high, returned almost to normal as a result of the administration of plasma. In contrast, serum prealbumin concentration decreased significantly after 36 h and continued to decrease, showing the course of failing liver function, until the patient's death 15 days after presentation. Prealbumin, a functional plasma protein synthesised in the liver, has a short half-life, is a true index of liver function, and seems to be a more reliable indicator of liver function in drug overdose than plasma enzymes, prothrombin-time, or plasma drug concentration.

Acetaminophen↗
PubMed1980

Isolation of intact larval haemoglobin from the brine shrimp Artemia salina. Prevention of degradation in vitro by proteases induced during larval development.

Haemoglobin induced in the larval stage of the brine shrimp, Artemia salina is extensively degraded when isolated from the later developmental stages of the larvae. Alkaline proteases appear in the organism a few hours after the induction of haemoglobin and cause the observed degradation. Addition of 2.6 mM phenylmethylsulphonyl fluoride or 20 micrograms/ml soybean trypsin inhibitor to the extraction buffer used for haemoglobin isolation prevents most of this degradation. Discrete haem proteins are found in extracts of the brine shrimp larvae isolated before induction of the proteases, and the major species has a molecular weight of over 200,000. This is believed to be the native haemoglobin. A spread of lower molecular weight haem-containing polypeptides is found in extracts of larvae isolated after induction of the proteases. These products are believed to result from degradation of the discrete haem proteins present in protease-free extracts.

Animals↗
PubMed1980

Influence of Hydrogen Peroxide upon Carbon Dioxide Photoassimilation in the Spinach Chloroplast: I. HYDROGEN PEROXIDE GENERATED BY BROKEN CHLOROPLASTS IN AN "INTACT" CHLOROPLAST PREPARATION IS A CAUSAL AGENT OF THE WARBURG EFFECT.

Photosynthesis and the Warburg effect (O(2) inhibition of photosynthesis) were evaluated in preparations of intact spinach chloroplasts enriched with varying amounts of lysed chloroplasts. Increasing the ratio of broken to intact plastids resulted in decreased rates of CO(2) assimilation.Hydrogen peroxide when added at 10 or more micromolar also inhibited photosynthesis in these preparations. Inhibition of the photosynthetic rate by both factors was eliminated by addition of catalase. These findings indicate that H(2)O(2) presumably generated by the broken chloroplasts was the causal agent of this inhibition.The Warburg effect also became more pronounced by increasing the level of broken to intact chloroplasts. This effect was examined as a function of added catalase, pH, and O(2) concentration. At 21% O(2) and 0.44 to 0.68 millimolar CO(2), catalase relieved the effect almost completely at pH 7.5, but at pH 8.3, the rate was restored only to about half or less of the control. At pH 7.6, 0.44 millimolar CO(2), and 100% O(2), the effect was only slightly overcome by catalase.A rise in glycolate synthesis by the isolated spinach chloroplast has been shown previously to be coupled to an increase in pH and O(2) (Kow, Robinson, Gibbs 1977 Plant Physiol 60: 492-495; Robinson, Gibbs, Cotler 1977 Plant Physiol 59: 530-534). At 21% O(2), glycolate synthesis was not affected by the addition of catalase at pH 7.5 or 8.3. It is proposed that at 21% O(2) and without some means of removing H(2)O(2), that portion of the Warburg effect attributed to glycolate synthesis has been overestimated at pH values in the order of 7.5. In contrast, that portion of the Warburg effect which was, at alkaline pH, insensitive to catalase represented the stress placed upon the photosynthetic carbon reduction cycle which resulted from an enhanced synthesis of glycolate. At 100% O(2) aeration and pH 7.5 to 8.5, the Warburg effect may also represent O(2)-mediated inhibition of a Calvin cycle enzyme within the intact plastid.

Journal Article↗
PubMed1977

Nuclear oestrogen receptors and treatment of breast cancer.

In an attempt to improve the predictive value of oestrogen-receptor measurements in breast-tumour biopsy specimens, oestrogen receptor was measured at both cytoplasmic and nuclear levels. Although 33% of patients had receptors at both levels, another 17% had cytoplasmic but no nuclear receptors. Theoretically, this latter group would not be expected to respond to hormone therapy. 7% had nuclear but not cytoplasmic receptors. The six-month follow-up data for the group of patients with receptors at both cytoplasmic and nuclear levels suggests qualitatively that this group has a good chance of responding favourably to hormone therapy. Much larger numbers must be accumulated before quantitative conclusions can be reached.

Breast Neoplasms↗
PubMed1977

In vivo transfer of an R factor within the lower gastro-intestinal tract of sheep.

The transfer of an R factor from donor E. coli introduced into the rumen of adult sheep to strains of the coliform microflora resident post rumen in the lower gastro-intestinal tract was found to be greatly increased when the animals were subjected to a short period of starvation (ca. 24-48 h). This also resulted in coliform organisms containing the resistance determinants of the R factor being excreted for much longer periods, sometimes for months afterwards. As no antibiotic treatment was given to the animals during these experiments, possession of the R factor should have conferred no selective advantages on the host cells and other plasmids could possibly be transferred similarly in vivo in sheep or other ruminants and perhaps also within the gut of monogastric animals.

Animals↗
PubMed1977

Transfer of R factors from Escherichia coli to salmonellas in the rumen of sheep.

Adult sheep were given into the rumen c. 10(8) cells each of donor strains of E. coli containing an R factor and prospective salmonella-recipient organisms and were maintained on a diet of lucerne chaff; the animals excreted the organisms, remained healthy, and no transfer of the R factor was detected. When the animals were starved for 48 h before inoculation, the ruminal environment was altered so that, on resumption of feeding, small numbers (c. 10(2)-10(4) cells--less than one cell per ml of rumen fluid) of the introduced organisms were able to multiply and reach sufficient numbers for the transfer of R factors to occur within the rumen. One animal, given 7-8 X 10(3) cells of recipient S. lomita after starvation for 48 h, became a carrier of this organism. A second animal, given 4-4 X 10(2) cells of S. typhimurium after starvation for 48 h, developed acute, fatal salmonellosis 5 days later; at the time of death, large numbers of salmonella organisms (c. 10(9) cells per g) were present in the faeces; these included many (c. 10(6) cells per g) that had received the R factor by transfer in vivo. These results indicate that short periods of starvation may enhance the transfer of R factors and possibly other plasmids between suitable micro-organisms in vivo, and may increase the susceptibility of animals to pathogenic micro-organisms.

Animals↗