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Biomedical subjects

J Thompson

Publications and source records attributed to J Thompson.

At least 577 records · Page 32Linked to original sources
PubMed1988

Effect of field shaping on thermal pattern produced by external microwave.

Modification of external microwave heating pattern can be useful clinically to reduce undesired coupling to adjacent bone or soft tissues particularly in the head and neck region. A static phantom was used to measure the effect of symmetric and asymmetric shielding of part of the microwave field from a BSD MA 150 microwave applicator. Thermal patterns were altered in a reliable predictable pattern. This method has been used clinically with improved patient tolerance.

Diathermy↗
PubMed1988

Effects of tissue-type plasminogen activator (t-PA) on Streptococcus sanguis-infected endocardial vegetations in vitro.

The effects were studied of in-vitro exposure to tissue-type plasminogen activator (t-PA) on endocardial vegetations isolated from rabbits with Streptococcus sanguis endocarditis as well as on Str. sanguis-infected plasma clots. For both vegetations and clots t-PA induced lysis of the infected fibrin matrix, demonstrated by a release of streptococci into the incubation medium and by an increase in the concentration of fibrin degradation products. The clots decreased in weight, whereas only partial lysis of the vegetations was obtained. Addition of plasminogen to the incubation medium did not enhance the effect of t-PA on vegetations. Fibrinolysis by t-PA did not interfere with the antimicrobial action of benzylpenicillin on the bacteria in a fibrin matrix. It is concluded that t-PA can degrade the fibrin matrices of infected endocardial vegetations and plasma clots. Reduction of vegetation size by t-PA may prove to be useful in the treatment of bacterial endocarditis.

Animals↗
PubMed1988

Value of autopsy in internal medicine: a 1-year prospective study of hospital deaths.

In a university Department of Internal Medicine, we compared the clinical information, as written down immediately post mortem, with the demand for autopsy and with the autopsy findings during one complete year. Autopsies were performed in 143 of 306 consecutive deaths. In autopsied patients clinicians had recorded more diagnoses per patient, but with less certainty than in non-autopsied patients. Patients with a diagnosis of a solid tumour were autopsied less often, and patients with infections or gastrointestinal disease more often than the average patient. These findings indicate selection of cases for autopsy. In 41% of patients erroneous diagnoses were detected that might have influenced management of the patient. In 28% of patients autopsy offered no additional information about one or more diagnoses. Both the proportion of errors and the proportion of uninformative autopsies increased with decreasing clinical certainty about the diagnosis. We conclude that autopsy offers useful information in most cases, and that selection of cases for autopsy is probably not justified.

Adolescent↗
PubMed1988

Forced expiratory indices in normal Libyan children aged 6-19 years.

Forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were measured in 796 Libyan children (386 boys and 410 girls) with ages ranging from 6 to 19 years. Values in girls were significantly less than those in boys after allowance had been made for age and height. FVC and FEV1 correlated best with standing height but were also correlated with body weight. These results may be used as a source of standard values for Libyan children.

Adolescent↗
PubMed1988

The carcinoembryonic antigen gene family: structure, expression and evolution.

The molecular cloning of carcinoembryonic antigen (CEA) and several cross-reacting antigens reveals a basic domain structure for the whole family, which shows structural similarities to the immunoglobulin superfamily. The CEA family consists of approximately 10 genes which are localized in two clusters on chromosome 19. So far, mRNA species for five of these genes have been identified which show tissue variability in their transcriptional activity. Expression of some of these genes in heterologous systems has been achieved, allowing the localization of some epitopes. The characterization of a CEA gene family in the rat and a comparison with its human counterpart has been utilized in the development of an evolutionary model.

Amino Acid Sequence↗
PubMed1988

Multiple strokes due to atrial myxoma with a negative echocardiogram.

We report a patient with three cerebrovascular events involving the posterior circulation, one of which occurred in conjunction with central retinal artery occlusion. The patient had constitutional findings but had a normal cardiac examination, negative echocardiogram, and negative blood cultures. Angiography on two separate occasions revealed left vertebral artery occlusion. Repeat echocardiography 10 months later, at the time of the third stroke, revealed a left atrial mass consistent with myxoma. In patients with repetitive unexplained embolic events in different vascular distributions and constitutional findings suggestive of atrial myxoma, repeat noninvasive studies are indicated even if the initial workup is negative.

Cerebrovascular Disorders↗
PubMed1988

Radiographic signs of union of scaphoid fractures. An analysis of inter-observer agreement and reproducibility.

Inter-observer agreement and reproducibility of opinion were assessed for the radiographic diagnosis of union of scaphoid fractures on films taken 12 weeks after injury. Weighted kappa statistics were used to compare the opinions of eight senior observers reviewing 20 sets of good quality radiographs on two occasions separated by two months. There was poor agreement on whether trabeculae crossed the fracture line, whether there was sclerosis at or near the fracture and on whether the proximal part of the scaphoid was avascular. As a consequence, agreement on union also was poor; it appears that radiographs taken 12 weeks after a scaphoid fracture do not provide reliable and reproducible evidence of healing.

Carpal Bones↗
PubMed1988

The phosphoenolpyruvate:sugar phosphotransferase system in gram-positive bacteria: properties, mechanism, and regulation.

This review consists of three major sections. The first and largest section reviews the protein constituents and known properties of the phosphotransferase systems present in well-studied Gram-positive bacteria. These bacteria include species of the following genera: (1) Staphylococcus, (2) Streptococcus, (3) Bacillus, (4) Lactobacillus, (5) Clostridium, (6) Arthrobacter, and (7) Brochothrix. The properties of the different systems are compared. The second major section deals with the regulation of carbohydrate uptake. There are four parts: (1) inhibition by intracellular sugar phosphates in Staphylococcus aureus, (2) PTS-mediated regulation of glycerol uptake in Bacillus subtilis, (3) competition for phospho-HPr in Streptococcus mutans, and (4) the possible involvement of protein kinases in the regulation of sugar uptake via the phosphotransferase system. The third section deals with the phenomenon of inducer expulsion. The first part is concerned with the physiological characterization of the phenomenon; then the consequences of unregulated uptake and expulsion, a futile cycle of energy expenditure, are considered. Finally, the biochemistry of the protein kinase and the protein phosphate phosphatase system, which appears to regulate sugar transport via the phosphotransferase system, is defined. The review, therefore, concentrates on the phosphotransferase system, its functions in carbohydrate transport and phosphorylation, the mechanisms of its regulation, and the mechanism by which it participates in the regulation of other physiological processes in the bacterial cell.

Bacterial Proteins↗
PubMed1988

Cardiac arrest associated with halothane anesthesia in a patient receiving theophylline.

A case of a 10-year-old asthmatic patient who had cardiac arrest during induction for elective ear surgery is presented. The patient's serum theophylline level was 21.6 micrograms/mL one hour after surgery. It is likely that, since other factors that can contribute to cardiac arrest during the perioperative period were not present, the combined use of aminophylline and halothane was responsible.

Anesthesia↗
PubMed1987

Clinical features and management of malignant histiocytosis of the intestine.

This article documents the clinical course of nine patients diagnosed as having malignant histiocytosis of the intestine (MHI). Five patients had a history of gluten-sensitive enteropathy. This tumor commonly affects the small bowel in a widespread, patchy fashion causing ulceration, stricture formation, and perforation. Metastases to mesenteric nodes, liver, and the bone marrow were common. Although the diagnosis of MHI was often made at laparotomy, surgical resection, even when extensive, was not curative in any case. All nine patients were treated with a variety of chemotherapeutic regimes. This tumor proved chemosensitive, although response was usually brief and difficult to accurately evaluate. Chemotherapy was poorly tolerated because these patients were malnourished. In two cases small bowel perforation occurred, and in one gastrointestinal bleeding occurred after chemotherapy. Eight patients have died of disease from 0 to 16 months after the diagnosis was made, and a single patient is apparently cured 5+ years after completing chemotherapy. Malignant histiocytosis of the intestine has a characteristic clinical course. It is hoped that increased clinical awareness and early diagnosis will improve the outcome.

Adult↗
PubMed1987

Biosynthesis and stereochemical configuration of N5-(1-carboxyethyl)ornithine. An unusual amino acid produced by Streptococcus lactis.

In a recent communication (Thompson, J., Curtis, M. A., and Miller, S.P.F. (1986) J. Bacteriol. 167, 522-529) we described the purification and characterization of N5-(1-carboxyethyl)ornithine from cells of Streptococcus lactis 133. This unusual amino acid has not previously been found in nature. Radiotracer experiments presented here reveal that exogenous [14C]ornithine serves as the precursor for biosynthesis of [14C]arginine, [14C]N5-(1-carboxyethyl)ornithine, and [14C]N5-acetylornithine by cells of S. lactis K1 during growth in a defined medium lacking arginine. In the absence of both arginine and ornithine, cells of S. lactis K1 can also generate intracellular [14C]N5-(1-carboxyethyl)ornithine from exogenous [14C]glutamic acid. Previously we showed that the properties of N5-(1-carboxyethyl)ornithine prepared from S. lactis were identical to one of the two diastereomers [2S, 7S) or (2S, 7R] present in a synthetic preparation of (2S, 7RS)-N5-(1-carboxyethyl)ornithine. The two diastereomers have now been unambiguously synthesized by an Abderhalden-Haase condensation between (2S)-N2-t-butoxycarbonyl-ornithine and the chiral (2S)-, and (2R)-bromopropionates. By 13C-NMR spectroscopy it has been established that the preparation from S. lactis is exclusively (2S, 7S)-N5-(1-carboxyethyl)ornithine. has been demonstrated in a cell-free extract of S. lactis 133. The requirements for ornithine, pyruvic acid, and NAD(P)H suggest that biosynthesis of N5-(1-carboxyethyl)ornithine occurs via a reductive condensation mechanism. A general survey revealed that N5-(1-carboxyethyl)ornithine was produced only by certain strains of Group N streptococci. These findings may indicate a plasmid locus for the gene(s) encoding the enzyme(s) for N5-(1-carboxyethyl)ornithine biosynthesis.

Carbon Radioisotopes↗
PubMed1987

Thyroid hormones regulate expression of the neural cell adhesion molecule in adult skeletal muscle.

Adult rat skeletal muscle does not express detectable levels of neural cell adhesion molecule (N-CAM) and membrane activity mediated by nerve appears to repress the N-CAM gene. N-CAM expression in skeletal muscle can however be reinduced by hypothyroidism. Thyroidectomised rats re-express N-CAM mRNAs of 5.2 and 2.9 kb and Western blot analysis showed protein bands of 125 and 155 kDa. Immunofluorescence analysis also showed high levels of N-CAM in the sarcolemma. These changes in N-CAM expression could be reversed by treatment of hypothyroid rats with thyroxine. Thus thyroid hormones as well as neural influences appear to control N-CAM expression in skeletal muscle.

Animals↗