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Biomedical subjects

C M Roberts

Publications and source records attributed to C M Roberts.

At least 73 records · Page 4Linked to original sources
PubMed1987

Intrathoracic aspergilloma: role of CT in diagnosis and treatment.

The authors describe the computed tomographic (CT) appearances of aspergilloma in 26 patients. With narrow (3-mm) sections, a bone algorithm, and wide window settings, CT scans enabled accurate identification of both the forming aspergilloma as well as the mature fungus ball in 25 cases. The diagnostic accuracy of CT was confirmed histologically in nine cases. The radiologic concept of the aspergilloma as a solid mass partially surrounded by a crescent of air is no longer tenable as the only definite criterion for diagnosis. In cases in which this classic appearance is seen on CT scans, mobility is easily demonstrated with use of prone and supine positions. In other cases, the aspergilloma appears as an irregular spongework containing air spaces and filling the cavity, obliterating the air crescent sign. The fungus ball is therefore fixed and immobile. Forming aspergillomas can also be identified by the fungal strands that fall into the cavity lumen, trapping air and initiating the sponge-work appearance. The CT appearance in patients with positive precipitins is characteristic and allows earlier diagnosis than does conventional tomography.

Adult↗
PubMed1986

Activity of Chi recombinational hotspots in Salmonella typhimurium.

Chi sites have previously been shown to stimulate homologous recombination by the Escherichia coli RecBC pathway. To test the activity of Chi in another organism, bacteriophage lambda crosses were carried out in Salmonella typhimurium strains bearing the E. coli lambda receptor protein. Chi is active in these crosses in S. typhimurium, but is less active than in the same crosses carried out in E. coli. The lower Chi activity in S. typhimurium appears to be intrinsic to the S. typhimurium RecBC enzyme, since the Chi activity in E. coli-S. typhimurium hybrids depends on the species of origin of their RecBC enzyme. For these studies we constructed and F' factor and a pBR322-derived plasmid carrying the thyA+ recC+ recB+ argA+ region of the S. typhimurium chromosome.

Bacteriophage lambda↗
PubMed1983

Injection sclerotherapy for oesophageal varices in the elderly.

Thirty-seven patients admitted consecutively to the Gastroenterology Unit with haemorrhage from oesophageal varices were treated by injection sclerotherapy. The patients were subdivided according to age at presentation (below 65, over 65 years). The mortality and morbidity of the two groups, over the period of follow-up (mean 5.1 months) were compared. The risk of rebleeding was higher in the elderly (0.23 overall) than in the young (0.11 overall) and was reflected in the higher mortality, four of 14 elderly patients and four of 23 younger patients. A further three elderly patients succumbed to intercurrent illness during the same period. In three of the surviving elderly, complete resolution of varices was noted. Complications of sclerotherapy occurred in eight out of 51 injections in the elderly and six out of 97 in the young but were usually well tolerated. This study suggests that injection sclerotherapy is useful in the treatment of bleeding oesophageal varices in the elderly and suggests recommendations for improved survival.

Adult↗
PubMed1981

Purification of a branched-chain keto acid dehydrogenase from Pseudomonas putida.

We purified branched-chain keto acid dehydrogenase to a specific activity of 10 mumol/min per mg of protein from Pseudomonas putida grown on valine. The purified enzyme was active with 2-ketoisovalerate, 2-ketoisocaproate, and 2-keto-3-methylvalerate in a ratio of 1.0:0.8:0.7 but showed no activity with either pyruvate or 2-ketoglutarate. There were four polypeptides in the purified enzyme (molecular weights, 49,000, 46,000, 39,000, and 37,000). The purified enzyme was deficient in the specific lipoamide dehydrogenase produced during growth on valine (molecular weight, 49,000). Branched-chain keto acid dehydrogenase required L-valine, oxidized nicotinamide adenine dinucleotide, coenzyme A, thiamine pyrophosphate, and magnesium chloride. A partially purified preparation catalyzed the oxidation of 2-keto-[1-14C]isovalerate to [14C]carbon dioxide, isobutyryl-coenzyme A, and reduced nicotinamide adenine dinucleotide in equimolar amounts. Both the Km and the Vmax for 2-ketoisovalerate were affected by the addition of L-valine to the assay mixture. However, only the Vmax values for oxidized nicotinamide adenine dinucleotide and coenzyme A were affected when L-valine was present. This suggested that valine acted by affecting the binding of branched-chain keto acids to subunit E1 of the complex.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
PubMed1981

Regulation of paralytic experimental allergic encephalomyelitis in rats: susceptibility to active and passive disease reinduction.

Spleen cells obtained from Lewis inbred rats previously immunized with 50 microgram of guinea pig basic protein emulsified in complete Freund's adjuvant passively transferred paralytic experimental allergic encephalomyelitis (EAE) only following an in vitro conditioning period. The in vitro conditioning required the presence of either concanavalin A or encephalitogenic antigen. The conditioned cells caused passive paralytic EAE in recipients of 10 million viable cells. After recovery from passive paralytic EAE, animals were completely susceptible to additional attempts to induce EAE by active or passive means. Active EAE recovered rats were resistant to additional attempts to induce active EAE but were fully susceptible to passively induced EAE mediated by in vitro conditioned cells.

Animals↗
PubMed1980

Production rates of prostaglandin F, 6-keto-PGF1 alpha and thromboxane B2 by perifused human endometrium.

Human endometrium obtained from fresh hysterectomy specimens was perifused for 7 hr in 95% O2/5% CO2 at 37 degrees C. The phase of the menstrual cycle was determined by histological examination. The concentrations of PGF, 6-keto-PGF1 alpha and TxB2 in 20 min fractions of the perifusion medium were measured by radioimmunoassay and production rates were calculated in terms of dry weight of tissue. Biphasic patterns of production were observed; high initial values fell to about 20% at 2 hr and then increased to relatively stable values at about 4 hr which were maintained for the next 2 hr. During this latter period, production rates in endometria taken at different phases of the cycle differed markedly from each other; the production rates of PGF in secretory and early proliferative endometria were low (15.8 +/- 2.6, mean +/- SEM and 67.2 +/- 8.3 ng/min/g respectively) whereas they were high in late proliferative and premenstrual endometria (188.0 +/- 16.7 and 196.4 +/- 16.9 ng/min/g respectively). The patterns of production of 6-keto-PGF1 alpha and TxB2 were similar to those of PGF but the absolute values were much lower (less than 10%). We conclude that the observed rates of production of prostaglandins by perifused human endometrium are consistent with synthesis being stimulated either by estrogen or withdrawal of hormonal support and being inhibited by progesterone.

6-Ketoprostaglandin F1 alpha↗
PubMed1979

Liaison psychiatry.

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Education, Medical↗
PubMed1978

The role of enoyl-coa hydratase in the metabolism of isoleucine by Pseudomonas putida.

The purpose of the present study was to determine if the enoyl coenzyme A hydratase formed by Pseudomonas putida during growth on isoleucine was a unique enzyme specific for isoleucine metabolism. The highest levels of the hydratase were formed during growth on isoleucine intermediates and the lowest levels during growth on glutamate and glucose. Data from growth experiments revealed that 2-methyl-3-hydroxybutyryl coenzyme A hydratase, an enzyme unique to isoleucine metabolism and enoyl coenzyme A hydratase were coordinately induced, but that 3-hydroxyacyl coenzyme A dehydrogenase was under separate control. The hydratase was purified 180-fold from isoleucine cells, and its physical and catalytic properties reported. The highest activity was with crotonyl coenzyme A,Vmax = 1100 x 10(3) moles/min mole enzyme, next was tiglyl coenzyme A, Vmax = 61 x 10(3) moles/min mole enzyme, and last was 3-methyl-crotonyl coenzyme A, Vmax = 2.3 x 10(3) moles/min mole enzyme. Enzyme purified from butyrate cells had the same elution patterns during column chromatography and catalytic properties as the enzyme from isoleucine cells. These data support the conclusion that a single enzyme in P. putida is responsible for the hydration of both tiglyl coenzyme A and crotonyl coenzyme A.

Butyrates↗
PubMed1978

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