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Biomedical subjects

R Lee

Publications and source records attributed to R Lee.

At least 289 records · Page 16Linked to original sources
PubMed1989

Jugular venous bulb catheterization in infants and children.

Cross-brain oxygen extraction may be altered by coma, hyperventilation, hypothermia, or barbiturates, and has been demonstrated in adults and more recently in children to be related to functional neurologic recovery after a variety of brain injuries. However, measurement of cross-brain oxygen extraction in children is currently not a part of routine clinical care, partly because there have been no published attempts relating the technique of jugular venous bulb (JVB) catheterization and its complication in children. We catheterized the JVB to measure cerebral venous oxygen content and calculate cross-brain oxygen extraction in 26 deeply comatose neonates and children ranging in age from a few hours to 14 yr. Bedside catheterization using the Seldinger technique was successful in 25 children, with standard venous cutdown necessary in the remaining child. All JVB catheterizations were performed with parental consent and during continuous monitoring of the intracranial (ICP) or fontanelle, as well as arterial, pressure. ICP was not significantly altered by the cannulation procedure in any of the children studied, although the cannulation occurred early in the child's course when ICP was well controlled. Inadvertent carotid artery puncture with bleeding controlled by local pressure occurred in four children, and catheter malposition was confirmed on lateral skull xray in two others. Jugular venous bulb catheters remained in place for 2 to 7 days (average 3) and malfunction or obstruction of the catheter did not occur. Organisms were grown from three of 26 catheter tips submitted for culture, with peripheral blood cultures also positive for the same organisms in two of these.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

Hypoxic cardiomyopathy: acute myocardial dysfunction after severe hypoxia.

Five cases of acute transient myocardial dysfunction in previously well people after severe hypoxic episode are described. In all cases the hypoxic episode was associated with drug overdose and its complications. Pulmonary infiltrates on chest X-ray consistent with pulmonary edema developed in four cases and gated heart pool scanning confirmed severe cardiovascular dysfunction in all cases.

Adult↗
PubMed1989

Altered electrical responses of B-cells after goldthioglucose-induced lesions in the ventromedial hypothalamus.

Goldthioglucose was used to induce necrosis of the ventromedial hypothalamus in mice. This produced an obese mouse that exhibited syndromes associated with non-insulin dependent diabetes mellitus (NIDDM). We found enhanced glucose-induced electrical activity from B-cells with impaired neurotransmitter input. This information indicates that the electrical events of the B-cell plasma membrane are influenced by altered neurotransmitter input and may play a causal role in the enhanced secretory response.

Animals↗
PubMed1988

Effects of 1-epinephrine on hemodynamics and cardiac function in coronary disease: dose-response studies.

To assess the effects of elevated epinephrine levels on cardiovascular performance in patients with coronary artery disease (CAD), epinephrine was infused intravenously into eight patients with normal coronary anatomy and 22 patients with CAD at dose rates of 0.06, 0.12, 0.18, and 0.24 micrograms/kg/min. Hemodynamic responses to epinephrine were not significantly different between the two groups. However, contractility increased significantly more (P less than 0.05) and end-systolic volume decreased significantly more (P less than 0.025) in normal subjects than in those with CAD. Plasma norepinephrine concentrations increased significantly (P less than 0.05) at 0.24 micrograms/kg/min epinephrine, indicating activation of sympathetic nervous system. Epinephrine ischemic thresholds ranged from 652 to 3362 pg/ml. Patients with CAD compared with normal subjects had more frequent ventricular arrhythmias (55% vs. 25%), chest pain (50% vs. 13%), and ischemic ECG changes (73% vs. 13%). These results indicate that although epinephrine induced myocardial ischemia in CAD, hemodynamics and ventricular pump function were maintained.

Adult↗
PubMed1988

Identification of cDNA encoding an additional alpha subunit of a human GTP-binding protein: expression of three alpha i subtypes in human tissues and cell lines.

The guanine nucleotide-binding proteins (G proteins), which mediate hormonal regulation of many membrane functions, are composed of alpha, beta, and gamma subunits. We have cloned and characterized cDNA from a human T-cell library encoding a form of alpha i that is different from the human alpha i subtypes previously reported [Didsbury, J. R., Ho, Y.-S. & Snyderman, R. (1987) FEBS Lett. 211, 160-164 and Bray, P., Carter, A., Guo, V., Puckett, C., Kamholz, J., Spiegel, A. & Nirenberg, M. (1987) Proc. Natl. Acad. Sci. USA 84, 5115-5119]. alpha i is the alpha subunit of a class of G proteins that inhibits adenylate cyclase and regulates other enzymes and ion channels. This cDNA encodes a polypeptide of 354 amino acids and is assigned to encode the alpha i-3 subtype of G proteins on the basis of its similarity to other alpha i-like cDNAs and the presence of a predicted site for ADP ribosylation by pertussis toxin. We have determined the expression of mRNA for this and two other subtypes of human alpha i (alpha i-1 and alpha i-2) in a variety of human fetal tissues and in human cell lines. All three alpha i subtypes were present in the tissues tested. However, analysis of individual cell types reveals specificity of alpha i-1 expression. mRNA for alpha i-1 is absent in T cells, B cells, and monocytes but is present in other cell lines. The finding of differential expression of alpha i-1 genes may permit characterization of distinct physiological roles for this alpha i subunit. mRNA for alpha i-2 and alpha i-3 was found in all the primary and transformed cell lines tested. Thus, some cells contain all three alpha i subtypes. This observation raises the question of how cells prevent cross talk among receptors that are coupled to effectors through such similar alpha proteins.

Amino Acid Sequence↗
PubMed1988

What kind of strategic plan?

Planning has had a formal place in the NHS since the 1974 reorganisation, though not everyone regards it as effective. Before the next round of strategic planning begins Robert Lee examines the advantages and disadvantages of different approaches, and suggests the way ahead.

Forecasting↗
PubMed1988

Intraoperative chemotherapy with carbon particles adsorbing mitomycin C for gastric cancer with peritoneal dissemination in rabbits.

A new dosage form of activated carbon particles adsorbing mitomycin C (MMC-CH) was studied for its therapeutic effects on peritoneal dissemination in both animal experiments and preliminary clinical trials. Rabbits with peritoneal dissemination induced by intraperitoneal transplanted VX2 carcinoma were used as experimental models. Seven days after intraperitoneal transplantation of VX2 carcinoma, mitomycin C at 1 mg/kg in the form of MMC-CH or at 0.185 mg/kg in the form of mitomycin C aqueous solution was given intraperitoneally. The two doses were equal in toxicity. MMC-CH extended survival time statistically significantly longer than did mitomycin C aqueous solution. Preliminary clinical trial with MMC-CH has been made in eight patients with gastric cancer and peritoneal dissemination, with no control group. MMC-CH, 60 to 100 mg/person, was given intraperitoneally before the surgical wound was closed. Patients were observed for more than 1 year. Five of the eight patients survived more than 1 year, and the mean survival time was 13.9 months, whereas in the patients treated previously without MMC-CH the 1-year survival rate was 17% and the mean survival time was 6.5 months. Side effects were temporary and tolerable.

Adsorption↗
PubMed1988

Relationship between fasting serum tryptophan/large neutral amino acid ratio and reported hunger in subjects with diabetes.

Food intake regulation is influenced by serum amino acid (AA) ratios. The objectives of this study were to determine whether non-obese subjects with diabetes have normal serum AA ratios, and to see if AA ratios relate to perceived hunger. We therefore measured fasting serum AA in nine normal subjects on two occasions and 19 patients with diabetes on four occasions over a two month period. At the time of the blood samples, the subjects with diabetes were asked to rate how hungry they felt on a scale of -3 (very hungry) to +3 (very full). There were no significant differences between the mean AA ratios of normal and diabetic subjects. There was a positive correlation between reported hunger score and the ratio of serum tryptophan (TRP) to the sum of the concentrations of the other large neutral AA (LNAA) (r = 0.286, n = 78, p less than 0.05). The relationships between hunger and other AA ratios were not significant. Variations of the TRP/LNAA ratio within each subject did not relate to differences in hunger from day-to-day. However, there was a positive correlation between the mean TRP/LNAA ratio and mean hunger score of the different subjects (r = 0.495, n = 19, p less than 0.05). The relationships between TRP/LNAA ratio and body weight or hunger score were not significant. It is concluded that the serum AA ratios are normal in patients with diabetes. The data is consistent with the hypothesis that a low serum TRP/LNAA ratio causes increased feelings of hunger in different individuals.

Adult↗
PubMed1988

The glycaemic index: effect of age in insulin dependent diabetes mellitus.

It has been suggested that age effects the glycaemic index value of foods, although there is no data to support this. We therefore studied the blood glucose responses of bread and lentils in seven children (aged 7-17 years) and 10 adults (aged 27-74 years) with insulin dependent diabetes (IDDM). Although there were small differences in the shape of the blood glucose response curves in adults and children, the mean glycaemic index value for lentils was virtually identical in the two groups being 43 +/- 7 in the children and 44 +/- 10 in the adults. We conclude that, in IDDM, the glycaemic index is not affected by age.

Adolescent↗
PubMed1987

Isolation and functional comparison of bovine cardiac troponin T isoforms.

We report on the isolation of two bovine cardiac troponin isoforms which differ in sequence near the amino terminus of troponin T (Risnik, V. V., Verin, A. D., and Gusev, N. B. (1985) Biochem. J. 225, 549-552). The isoforms were isolated by direct separation on DEAE-cellulose and were also obtained by reconstitution of urea-dissociated subunits. The two isoforms were compared for their effects on processes involving interactions of troponin with tropomyosin and actin. The two isoforms had similar abilities to promote tropomyosin polymerization. They allowed equal potentiation, by high concentration of myosin subfragment 1, of the thin filament-activated MgATPase rate. In the presence of lower concentrations of myosin subfragment 1, the MgATPase rate was 96% sensitive to Ca2+, regardless of which troponin isoform was present. The Ca2+ concentration required to activate the MgATPase rate was similar but not identical for thin filaments containing one isoform or the other. In the presence of the smaller isoform, the Ca2+-activation curve is shifted 0.1 to 0.15 pCa units to the left. At 10(-6) M Ca2+ the MgATPase rate is 50% greater when the smaller troponin T isoform is present than when the larger is present. These results indicate that the variable region of troponin T influences the overall response of the thin filament to Ca2+, and raises the possibility that regulation of this region by mRNA splicing may modulate muscle function.

Actin Cytoskeleton↗