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Biomedical subjects

J T Smith

Publications and source records attributed to J T Smith.

At least 145 records · Page 8Linked to original sources
PubMed1985

A follow-up survey of transferable, plasmid-encoded trimethoprim resistance in a general hospital (1975-1983).

Urinary isolates of bacteria resistant to trimethoprim were collected at the Whittington Hospital, London, during five three-monthly periods during 1975, 1977, 1979, 1981, and 1983. Seventy-six transferable trimethorpim-resistant isolates so obtained were examined for their antibiotic resistance patterns, trimethoprim resistance (TpR) levels and plasmid molecular weights. Overall between 1975 and 1983 the frequency of transferable TpR rose from 10% to 40% of trimethoprim-resistant isolates, caused mainly by an increasing number of Escherichia coli isolates which cotransferred antibiotic resistance to trimethoprim, streptomycin and spectinomycin. From 1975-1979 the rise in the frequency of transferable TpR was due to a gradual increase amongst in-patient isolates but since 1979 transferable TpR rose rapidly due to a ten-fold increase in out-patient isolates.

Cross Infection↗
PubMed1985

Escherichia coli thymine auxotrophs suppressible by carbon dioxide.

Two independently-isolated thymine-requiring mutant strains of Escherichia coli were found to possess an unusual phenotype: in the presence of CO2, growth was independent of thymine. The two strains showed different profiles of temperature sensitivity. Glycine, serine and methionine were unable to relieve the thymine-dependence. Both strains were susceptible to trimethoprim under conditions where they were thymine-independent. The results are consistent with the occurrence of partial defects in thymidylate synthase.

Carbon Dioxide↗
PubMed1985

Using the correct standard errors in comparing subpopulation survival rates in marked populations.

We give estimates of variances and covariances of survival rates for subgroups of a wild population surveyed by mark-recapture methods. These are used in forming test statistics to compare subgroup survival rates. We show that using correct standard errors based on the appropriate approximate sampling model and incorporating important covariances of observed frequencies avoids spurious significance of survival rate differences.

Analysis of Variance↗
PubMed1984

Mutational resistance to 4-quinolone antibacterial agents.

The activity of ten 4-quinolone drugs was tested against five Escherichia coli mutants. Mutational resistance was found to reduce the activity of all ten drugs, indicating that they display biochemical cross-resistance with each other. However, ciprofloxacin and, to a lesser extent, ofloxacin and norfloxacin were so highly active that the most resistance exhibited by any mutant fell well within the serum drug concentration ranges attainable in humans. Hence, clinical cross-resistance in Escherichia coli at least, need not necessarily apply to such highly active 4-quinolone antibacterial agents.

Anti-Bacterial Agents↗
PubMed1984

Pelvic osteotomy: an alternative to total hip replacement in the young adult.

For the young adult patient with a painful hip in whom there is acetabular dysplasia, innominate osteotomy is not only an alternative to total hip replacement, but rather it is the procedure of choice. If the prerequisites for a Steel or a Chiari osteotomy are met and if the procedures are adequately carried out, satisfactory relief of pain and return to function can be expected. The length of the satisfactory result is unknown as yet because an insufficient number of patients have been followed over a long enough period to determine the life expectancy of these procedures. It would appear, however, that it is going to be more than 10 years, which is certainly longer than one could expect for the current generation of cemented total joint replacements to last. Cementless total joint replacements are so new that a comparison cannot be made, but intuitively, a procedure that can leave the patient with his own tissue is the procedure of choice. Certainly, in a well-executed Steel or Chiari osteotomy, later reconstruction or total joint replacement will not be compromised.

Acetabulum↗
PubMed1983

R-plasmid effects on bacterial multiplication and survival.

The multiplication of Escherichia coli C containing either the plasmid R46 or its non-selftransmissible derivative was studied in the presence or absence of the isogenic R- parent strain. Neither plasmid conferred any detectable effect on the host's ability to multiply. Similarly under conditions of prolonged incubation neither plasmid conferred a disadvantage on its host when the bacteria were grown in pure culture. However, when the incubation of mixed R+/R- cultures was prolonged, the possession of either R-plasmid resulted in small but reproducible differences which favoured the R- strain.

Escherichia coli↗
PubMed1983

Prognostic Nutritional Index: its usefulness as a predictor of clinical course.

Despite mounting evidence, a question still exists as to the true clinical relevance of varying degrees of malnutrition, the role of currently measured nutritional parameters in identifying malnutrition and predicting clinical risk in individual patients, and the efficacy of nutritional therapy. This study was designed to document the usefulness of the Prognostic Nutritional Index (PNI) as a predictor of clinical course. The nutritional assessments and clinical records of 328 subjects in a Veterans Administration Hospital were reviewed, PNI and complication rates were determined for each of the subjects, and the data statistically analyzed. The PNI was found to be a useful indicator of malnutrition and predictor of clinical course. The PNI appeared to be a more sensitive index of clinical outcome than did comparison of individual nutritional parameters to accepted norms, although it accounted for only 17% of the information needed to predict clinical course perfectly.

Adult↗
PubMed1983

The influence of cysteine and methionine supplements on polyamine biosynthesis in the rat.

Previous reports from this laboratory have shown that supplementation of diets containing the optimal level (0.02%) of dietary inorganic sulfate (SO4(2-] with cysteine instead of methionine can affect several metabolic pathways. It is possible that these results reflect alterations in the biosynthesis of potent physiological compounds, the polyamines. Adult male albino rats were fed diets containing 15% casein and a constant level of inorganic sulfate (0.02%) supplemented with cysteine (0.505%) or methionine (0.62%). The polyamines (putrescine, spermidine and spermine) and the controlling enzymes for their biosynthesis ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (SAMD) were evaluated in liver, kidney and brain tissue homogenates following a 17-day dietary period. Rats fed the diet supplemented with cysteine had increased ODC activity and decreased SAMD activity when compared to rats fed diets supplemented with methionine. Polyamine concentrations varied in tissues with a trend toward increasing amounts in animals fed the cysteine-supplemented diet. Based on these data, it appears that dietary cysteine stimulates the biosynthesis and increased tissue concentration of polyamines.

Adenosylmethionine Decarboxylase↗
PubMed1983

A metabolic comparison of cysteine and methionine supplements in the diet of a rat.

Adult male Long-Evans rats (250-300 g) were fed diets containing 15% of casein not supplemented with amino acids, supplemented with 0.505% cysteine or supplemented with 0.620% methionine for a period of 17 days. Rats fed the diets supplemented with cysteine had an increased incorporation of the 14C-radioactivity from [U-14C]alanine into liver glycogen and a decreased incorporation from [U-14C]acetate into fatty acids. Pyruvate carboxylase activity was slightly increased and citrate cleavage enzyme activity decreased in the livers of those rats fed the diets supplemented with cysteine. Rats fed diets supplemented with methionine had a decreased liver phosphoenolpyruvate carboxykinase activity. Based on these data it appears that rats fed diets supplemented with cysteine adapt metabolically to store energy as glycogen, while those fed diets supplemented with methionine tend to store energy as lipid.

Animals↗
PubMed1983

An effect of dietary sulfur on liver inorganic sulfate in the rat.

The effect of dietary sulfur on liver inorganic sulfate concentration was determined by feeding rats diets containing 0.0002, 0.02, 0.1 and 0.42% of inorganic sulfate for a period of 17 days. Each diet contained 15% of casein supplemented with decreasing levels of methionine as the dietary inorganic sulfate was increased, to keep the sulfur as sulfate concentration constant at 0.67%. The molarity of the liver sulfate calculated on the basis of moles of sulfate per 1,000 g of wet tissue was 0.98, 1.3, 2.2 and 1.5 mM for rats fed the diets containing 0.0002, 0.02, 0.1 and 0.42% of inorganic sulfate, respectively. Thus it appears that the liver sulfate pool is limited by a combination of the rate of oxidation of the sulfur-containing amino acids and the extraction of sulfate from the portal system.

Animals↗
PubMed1983

The Eastern Ontario survey: a study of drug-treated psychiatric problems in the mentally handicapped.

This study surveyed psychiatric problems treated with psychotropic medication among mentally handicapped at five regional centres in Eastern Ontario. Of the 2,158 residents studied, 920 (43%) were identified as problem cases, ranging from 36% to 83% in different institutions. Aggressivity, hyperactivity, and self-injury are the most prevalent conditions among more than thirty problem categories. Analysis of multidimensional contingency tables revealed that each of these three problems is involved with a distinct pattern of interactions with the set of demographic and clinical variables. The diversity of these interaction patterns points out the inadequacy of any unitary hypothesis of the pathogenesis and the inadvisability of adopting over-generalized treatment modalities. It is proposed that rational planning of service should rely on a realistic estimation of individuals' needs and a better understanding of the scope and nature of the problem.

Adult↗
PubMed1983

Regional distributions of choline acetyltransferase and acetylcholinesterase activities in layers of rat cerebellar vermis.

Entire sagittal sections of rat cerebellar vermis were dissected into microgram-sized samples of molecular, granular, and white matter layers. Assayed activities of choline acetyltransferase and acetylcholinesterase were plotted back onto sectional maps of exact sample locations. On the average, the activities of choline acetyltransferase and acetylcholinesterase in the granular layer were about four and five times, respectively, those in the molecular layer. The highest activity of both enzymes was in the granular layer of the vestibulocerebellum, the nodulus and ventral uvula (lobules X and IXc of Larsell). This activity might be related to the secondary vestibulocerebellar projection, terminating as mossy fibers in the granular layer of this region. Intermediate levels of activity were found in the granular layer of the dorsal uvula (lobule IX, a and b). The lowest activities of both enzymes in the granular layer were in the culmen (lobule V). A 7.1-fold difference in choline acetyltransferase activity and a 4.5-fold difference in acetylcholinesterase activity were found between the granular layer of lobules V and X. The numerical density of aggregates of acetylcholinesterase staining product in the granular layer correlated much better with assayed acetylcholinesterase activity than with choline acetyltransferase activity.

Acetylcholinesterase↗
PubMed1982

An effect of sulfur nutrition on the metabolism of salicylamide.

The effect of supplementing diets containing 15% casein with inorganic sulfate and/or the sulfur-containing amino acids on the metabolism of salicylamide was determined. The glucuronide-salicylamide:sulfate-salicylamide (GS:SS) ratio in the urine of rats fed the diets containing 15% of casein without inorganic sulfate or sulfur containing amino acid supplementation approached unity. Addition of either 0.02% of inorganic sulfate or 0.625% of methionine reduced this ratio to approximately 0.3%. Addition of 0.325% of methionine or sufficient cysteine to be equimolar with 0.625% methionine did not lower the GS:SS ratio significantly. Therefore, it appears that not only the level but the source of sulfur may be important in the detoxication of drugs.

Animals↗
PubMed1981

Escherichia coli 5'-nucleotidase: purification, properties and its release by osmotic shock.

Escherichia coli 5'-nucleotidase was purified to apparent homogeneity as judged by polyacrylamide gel electrophoresis. Its molecular weight was estimated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis, by gel exclusion chromatography, and by membrane filtration; values of 66 000, 48 500, and 15 000 to 30 000, respectively, were obtained. The enzyme was completely released from bacteria by osmotic shock treatment. The apparently anomalous behaviour of 5'-nucleotidase in terms of the molecular sieving hypothesis for the release of enzymes by osmotic shock proposed by Smith & Wyatt (1974) and extended by Broad & Smith (1979) is discussed.

5'-Nucleotidase↗