Search PubMed⌕ Search

Biomedical subjects

J R Thompson

Publications and source records attributed to J R Thompson.

At least 19 recordsLinked to original sources
PubMed1992

Alterations in substrate utilization in the reperfused myocardium: a direct analysis by 13C NMR.

An alternative 13C NMR method which allows direct determination of substrate oxidation in tissue for up to three competing 13C-enriched substrates is presented. Oxidation of competing substrates can be measured by 13C NMR spectroscopy under non-steady-state conditions if the relative areas of the glutamate C3 and C4 resonances can be determined. The accuracy of this measurement is limited during brief exposure to 13C-enriched substrates because of the low enrichment in the C3 carbon. The glutamate C4 resonance from a tissue sample which has oxidized a combination of [1,2-13C]acetate (or a uniformly enriched fatty acid mixture) and [3-13C]lactate appears as a nine-line resonance consisting of four multiplet components: a singlet (C4S), two doublets with differing one-bond coupling constants (C4D34 and C4D45), and a quartet (C4Q). It is shown that the sum of the C4S + C4D34 resonance areas versus the C4D45 + C4Q resonance areas directly reports the relative utilization of [3-13C]lactate versus [1,2-13C]acetate, respectively, regardless of citric acid cycle intermediate pool sizes or carbon flux through anaplerotic reactions. We also show that homonuclear 13C decoupling of the glutamate C2 resonance collapses the C3 resonance multiplet into an apparent triplet (actually, a singlet plus a doublet); the relative area of the singlet component reflects the amount of unlabeled acetyl-CoA entering the cycle. The method has been used to determine the contribution of lactate/acetate/glucose to acetyl-CoA in normoxic and reperfused rat hearts.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetates↗
PubMed1992

A scoring system for lung function tests in infants.

Measurements of thoracic gas volume (TGV), airway resistance (Raw), and airway conductance (Gaw) were calculated in a group of 42 normal infants using a whole-body plethysmograph. Maximum expiratory flow at functional residual capacity was measured in a separate group of 108 normal infants. Using data obtained from these infants the following regression equations were calculated: Gaw (L.s-1.cmH2O) = -0.0475 + 0.00164 x length (cm) square root of TGV (mL1/2) = -3.22 + 0.263 x length (cm) VmaxFRC (mL.s-1) = -173 + 5.2 x length (cm). The standard errors of prediction are a measure of the scatter of individual results from the normal population about the true regression line. They were used to define limits of the normal ranges for these tests of lung function, and to develop a scoring system. This approach is preferable to expressing results as percent predicted, which gives no indication of how likely a measurement is to be within normal limits.

Age Factors↗
PubMed1992

Effects of size and growth time of a murine sarcoma on its metastatic spread.

The effects of the size of an implanted tumor and of its time of growth on metastasis were examined in the same tumor grown under two different conditions. Tumors were implanted either in the untreated legs of mice or in legs that had been irradiated one day earlier. The radiation slowed the growth of tumors. When the tumors grew to predetermined diameters, the legs were excised and 20 days later the mice were examined for the presence of lung metastases. Equal changes in the time to excision of the tumors grown under the two conditions led to nearly equal changes in the proportions of animals with metastases. Tumor volume effects were not apparent in this consideration of changes in metastasis rates with time. This work reanalyses the data of that study using the variability in growth rates within a tumor growth condition to investigate the effect of tumor size on metastatic intensity. This intensity increased at least linearly with tumor volume for both irradiated and control animals. The finding of equal effect at equal growth times of the implanted tumors under the two growth conditions was confirmed but is due to: (1) metastatic intensity changing five times as rapidly with tumor size in the irradiated group as compared to the control group and (2) non-exponential retarded growth of the tumors in the control treatment group.

Animals↗
PubMed1992

Occlusion for amblyopia: a comprehensive survey of outcome.

The results of a long term follow up of all patients from a single health district started on occlusion for amblyopia in 1983 are reported. Three hundred and sixty-eight patients started treatment, their average age was four years seven months, the average amount of daily occlusion was 1.5 hours and the average length of follow up was 31 months. 37% of cases achieved a final visual acuity of 6/9 or better and another 33% a visual acuity of 6/12 or 6/18.23% did not achieve 6/18 and treatment of these patients was regarded as failure. Data for the remainder (7%) were incomplete. The success rate of occlusion treatment varied little with the age of starting treatment. The group with combined strabismus and anisometropia responded least well to treatment.

Age Factors↗
PubMed1992

Deoxyribonucleic acid (DNA) ploidy and proliferative characteristics of metastatic squamous cell carcinoma determined by flow cytometric analysis.

BACKGROUND: The deoxyribonucleic acid (DNA) index and the proliferative index (the fraction of cells in the S phase) can be independent prognostic indicators of the biologic aggressiveness of certain malignant neoplasms. OBJECTIVE: To determine whether the DNA index or proliferative index could predict metastases in cutaneous squamous cell carcinoma. METHODS: Nineteen different metastases from 15 patients with primary cutaneous squamous cell carcinoma (SCC) were reviewed, graded, and had DNA proliferative indexing performed by fluorescent activated cytometry. A control group of 13 patients with primary cutaneous SCC without metastases were studied in a similar manner. RESULTS: No significant difference between the metastatic and the nonmetastatic SCC groups for either DNA index or proliferative index (non-paired t-test) was observed. No correlative association with histologic grading with DNA index or proliferative index was observed for either group. CONCLUSION: We conclude that aneuploidy and S-phase fraction by fluorescent activated cytometry are not significant predictors of potential metastases in cutaneous squamous cell carcinoma.

Carcinoma, Squamous Cell↗
PubMed1992

Splenectomy in cattle via transthoracic approach.

Sixty-eight cattle under general anesthesia were splenectomized. The transthoracic approach was used to provide better access to the spleen and to facilitate ligature of the major splenic vessels. The procedure was easier and less time-consuming, compared with other surgical approaches, and is considered to be less stressful to the animals. Post-operative recovery was complete in 67 of 68 cattle. After surgery, 1 animal developed respiratory tract disease that was thought to have been unrelated to the surgery.

Anesthesia, General↗
PubMed1991

Glutamine metabolism in skeletal muscles from the broiler chick (Gallus domesticus) and the laboratory rat (Rattus norvegicus)

Oxidative decarboxylation of L-[1-14C]glutamine was studied in isolated chick and rat skeletal muscles incubated in the presence of glucose, insulin and plasma concentrations of amino acids. (1) The rate of oxidative decarboxylation of L-[1-14C]glutamine was high, and exceeded that of L-[1-14C]leucine in all muscles. (2) The rate of oxidative decarboxylation of L-[1-14C]glutamine increased with increasing intracellular concentrations of glutamine. (3) The activities of glutamine aminotransferases K and L were more than 10-fold greater in rat than in chick skeletal muscles. (4) Mitochondrial phosphate-activated glutaminase activity was approx. 10-fold greater in chick than in rat skeletal muscles and increased with increasing glutamine concentrations. (5) An inhibitor of glutaminase, 6-diazo-5-oxo-L-norleucine, inhibited the rate of glutamine decarboxylation in chick, but not in rat, skeletal muscle. These findings suggest that glutamine degradation in skeletal muscle may be substantial and may make an important contribution to the regulation of intramuscular glutamine concentrations. A species difference in the pathways and the subcellular location for the conversion of glutamine into 2-oxoglutarate in rat and chick skeletal muscles is implied by the relative activities of glutamine-degrading enzymes.

Animals↗
PubMed1991

The effect of ketone bodies on nitrogen metabolism in skeletal muscle.

1. The ketone bodies, D-beta-hydroxybutyrate and acetoacetate, inhibit glycolysis thereby reducing pyruvate availability which leads to a marked inhibition of branched-chain amino acid metabolism and alanine synthesis in skeletal muscles from fasted mammalian and avian species. 2. The rate of glutamine release from skeletal muscles from fasted birds is increased at the expense of alanine in the presence of elevated concentrations of ketone bodies because of an increase in the availability of glutamate for glutamine synthesis. 3. Ketone bodies inhibit both protein synthesis and protein degradation in skeletal muscles from fasted mammalian and avian species in vitro. The mechanisms involved remain unknown. 4. Inhibition of amino acid metabolism and protein turnover in skeletal muscle by ketone bodies may be an important survival mechanism during adaptation to catabolic states such as prolonged fasting.

Acetoacetates↗
PubMed1991

The incidence and prevalence of amblyopia detected in childhood.

We present incidence estimates for amblyopia using data from a study of a cohort of 364 children from a single English county who were referred during 1983 for occlusion therapy. Using a criterion of a visual acuity of 6/12 or worse to define amblyopia, we estimate that 3.0% of the county's children develop the condition. Successful treatment of some of these children means that 1.9% will remain amblyopic as adults.

Adolescent↗
PubMed1991

Doppler ultrasound studies in renal arteries of normal newborn babies.

The renal arteries of 89 healthy full-term infants were examined using duplex Doppler ultrasonography to establish a normal range for renal blood flow velocity in the first 3 days of life. In the first 24 h a wide range of renal blood flow velocities was noted with a statistically significant decrease in Pourcelot's index over the next 2 days.

Humans↗
PubMed1991

Antagonistic effect of atipamezole on xylazine-induced sedation, bradycardia, and ruminal atony in calves.

Three doses of an alpha 2-adrenoreceptor antagonist, atipamezole, were administered to reverse xylazine-induced sedation, bradycardia, and ruminal atony in calves. Once a week for 4 weeks, each of 6 calves was administered IV 1 treatment of: 0.3 mg of xylazine/kg of body weight, followed in 10 minutes by 1 ml of 0.9% NaCl; 0.3 mg of xylazine/kg, followed in 10 minutes by 3 micrograms of atipamezole/kg; 0.3 mg of xylazine/kg, followed in 10 minutes by 10 micrograms of atipamezole/kg; or 0.3 mg of xylazine/kg, followed in 10 minutes by 30 micrograms of atipamezole/kg. The order of the 4 treatments in each calf was selected at random. Xylazine alone caused lateral recumbency for 33.6 +/- 7.1 minutes (mean +/- SEM). Atipamezole administered at dosages of 3, 10, and 30 micrograms/kg shortened xylazine-induced lateral recumbency to 20.5 +/- 3.0, 10.2 +/- 0.2, and 9.3 +/- 0.5 minutes, respectively. Calves given xylazine alone stood at greater than 60 minutes after the onset of recumbency. Atipamezole given at 3, 10, and 30 micrograms/kg shortened the time from onset of lateral recumbency to standing to 40.2 +/- 6.9, 12.8 +/- 1.1, and 10.0 +/- 0.7 minutes, respectively. Drowsiness was found in calves given the lowest dosage of atipamezole (3 micrograms/kg) after the calves stood. Atipamezole given at dosages of 10 and 30 micrograms/kg reversed xylazine-induced ruminal atony in a dose-dependent manner. In addition, 30 micrograms of atipamezole/kg reversed xylazine-induced bradycardia, but the lower dosages of this antagonist did not. Results indicated that 30 micrograms of atipamezole/kg should be a useful antidote for xylazine overdose in cattle.

Adrenergic alpha-Antagonists↗
PubMed1991

Role of potassium in the pathogenesis of acute renal failure.

Potassium depletion can potentiate several experimental models of acute renal failure. It causes renal vasoconstriction, probably under the influence of vasoconstrictor prostaglandins and angiotensin II, and causes a reduction in vasodilatory prostaglandins. Aminoglycoside nephrotoxicity in experimental animals and in man causes a reduction in serum potassium and in animals it enhances the functional and histological damage produced by aminoglycosides. Chronic potassium loading protects against mercuric chloride, uranyl nitrate, and gentamicin models of acute renal failure. In the gentamicin model, protection is associated with a stimulation of renal cortical Na-K-ATPase activity and a reduction in the level of gentamicin accumulated in cortical tissue. In the clinical setting, potassium deficiency should be avoided in patients at risk for acute renal failure. However, potassium loading should also be avoided, since a falling glomerular filtration rate in the presence of a potassium load could result in potentially serious hyperkalemia.

Acute Kidney Injury↗
PubMed1991

Perspectives in multiple myeloma: survival, prognostic factors and disease complications in a single centre between 1975 and 1988.

One hundred and forty-one patients with multiple myeloma, diagnosed at the City Hospital, Nottingham between January 1975 and October 1986, were followed until death or for at least two years in a retrospective study. Overall median survival was 25 months, with no significant improvement occurring during the study period; increasing age, ESR and serum creatinine concentration at diagnosis were independent predictors of shortened survival. Renal impairment developed in 56 per cent of patients but only 7 per cent died of renal failure. At least one episode of infection occurred in 55 per cent of patients, most commonly in the first month. There was a significant rise in the overall incidence of infection and in the proportion caused by Gram-negative bacteria during the study period. Raised serum urea and low haemoglobin concentrations at diagnosis were independent risk factors for subsequent infection. Infection was associated with 2.75-fold increased risk of death, independent of other risk factors. Prevention of infection is an important aim for improvements in the survival of patients in multiple myeloma.

Adult↗
PubMed1991

Comparison of normal saline and heparin solutions for maintenance of arterial catheter patency.

A double-blind, randomized study was conducted in 30 adult medical intensive care unit patients to determine if the presence of heparin in continuous-flush solutions prolongs the functional life span of radial arterial catheters compared with catheters flushed with solutions not containing heparin. Patients were consecutively entered into the study and randomly assigned to receive arterial line flush solutions containing 0.9% sodium chloride (NSS) or heparin 4 U/ml in 0.9% sodium chloride. The flow rate of each flush solution was approximately 3 ml/hr. Use of the heparin-containing flush solution resulted in a catheter survival rate of 86% at 96 hours compared with a rate of only 52% after 40 hours with NSS (p less than 0.05). In addition, the heparin-flushed catheters required significantly less manipulation to prevent catheter occlusion and arterial pressure-wave dampening (p less than 0.01). The use of NSS as a continuous flush for radial artery catheters is associated with an increased frequency of catheter occlusion and malfunctions compared with solution containing heparin, and thus is not recommended in patients with normal coagulation status and platelet count.

Catheterization, Peripheral↗