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Biomedical subjects

T Henderson

Publications and source records attributed to T Henderson.

At least 55 records · Page 3Linked to original sources
PubMed1987

Fetal metabolism and placental transfer of vasoactive intestinal peptide in sheep.

Vasoactive Intestinal Peptide (VIP) is a 28-amino-acid putative neurotransmitter that may have a role in the regulation of myometrial blood flow and uterine contractility. The chronically cannulated fetal sheep preparation was used to examine the fetal clearance and placental transfer of VIP. Metabolic Clearance Rate (MCR) and placental transfer of VIP were measured by alternate steady-state infusion of VIP into the mother and fetus. Plasma concentrations of VIP were measured by radioimmunoassay. MCR was similar in the pregnant (45 +/- 10 ml/kg/min) and nonpregnant ewes (35 +/- 5 ml/kg/min). However, compared to both pregnant and nonpregnant ewes, fetal MCR was significantly increased at 77 +/- 15 ml/kg/min, indicating highly developed clearance mechanisms in the fetus. VIP did not cross the placenta in either direction. Both the placenta and fetal liver metabolized VIP and contributed to the elevated fetal clearance of VIP. The results show that VIP in fetal tissue is unlikely to influence maternal uterine activity with any VIP-mediated effects emanating from maternal and/or placental sources.

Animals↗
PubMed1987

Primary anastomotic bonding in polytetrafluoroethylene grafts?

Previous studies have demonstrated that standard knitted and woven fabric grafts are forever dependent on the suture material for anastomotic tensile strength. Clinical experience with polytetrafluoroethylene (PTFE) and double velour knitted grafts have shown that there is extensive fibrous capsular bonding between the graft and the surrounding tissues. This would lead to increased anastomotic tensile strength. To test this theory, 34 mongrel dogs underwent replacement of their infrarenal aortas with grafts made of PTFE (10 dogs), of double velour knitted Dacron (DVD, 11 dogs), of single velour knitted Dacron (SVD, 5 dogs), and of woven Dacron (WD, 8 dogs). One anastomosis was constructed with 5-0 Prolene and the opposite anastomosis was constructed with 5-0 Dexon (average absorption time, 21 days). In five grafts each of PTFE and DVD, as well as in all eight WD grafts, the midgraft was divided and resutured with 5-0 Dexon. All grafts were harvested together with adjacent proximal and distal aorta between 3 and 10 months from the time of implantation. The tensile strength of each anastomosis was measured with a tensiometer. The mean graft-to-artery (absorbable suture) anastomotic tensile strength, in pounds, for PTFE (14.3) and DVD (12.6) was significantly higher than that for SVD (6.9) or WD (7.2) (p less than 0.003). Graft-to-graft anastomotic tensile strength for PTFE (mean 17.3) was significantly better than that for DVD (mean 9.0; p less than 0.03) or WD (mean 7.9; p less than 0.001). Analysis of anastomotic tensile strength as a function of time revealed continued increase in PTFE in contrast to a slow decline with time in DVD.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Specificity of the hydrochloric-acid-modified Crithidia luciliae immunofluorescence assay for detection of antibody to native DNA.

The Crithidia luciliae immunofluorescence (CLIF) assay is widely used to detect antibodies to native dsDNA in the diagnosis and management of systemic lupus erythematosus (SLE). However, sera from patients with SLE, rheumatoid arthritis, systemic sclerosis, drug-induced lupus erythematosus, and Sjogren's syndrome have given false-positive CLIF results. The frequency was 5% for SLE, 16% for drug-induced LE, and 5% for rheumatoid arthritis. Such false positivity was effectively eliminated by pretreatment of Crithidia luciliae smears with 0.1 N HCl. Hydrochloric acid pretreatment of Crithidia luciliae smears renders the CLIF test more specific for the detection of anti-dsDNA antibodies, without sacrificing its sensitivity and specificity. In the future, modification of routine Crithidia luciliae immunofluorescence with 0.1 N HCl pretreatment is recommended.

Antibodies, Antinuclear↗
PubMed1985

Nonstress testing in a physician's office--a five-year experience.

A study was undertaken to evaluate the use of nonstress testing in a physician's office in the management of high-risk pregnancies. A total of 1,485 office nonstress tests were done on 713 high-risk patients between 32 and 43 weeks' gestation. When indicated the contraction stress test was done in hospital. In all, 485 patients had a nonstress test within a week of their delivery, 97% of which were reactive and 2% were nonreactive. Those fetuses with a nonreactive test result had a significantly increased incidence of abnormal fetal heart rate patterns during labor and intrapartum fetal distress leading to cesarean delivery. With strict adherence to a protocol, nonstress testing in the physician's office can be successful in caring for fetuses thought to be at risk.

Ambulatory Care↗
PubMed1984

Potential wildlife sources of Yersinia pseudotuberculosis for farmed deer (Cervus elaphus).

During 1982 and 1983 15 serotype I, 6 serotype II, 1 serotype III and 3 untyped strains of Yersinia pseudotuberculosis were isolated from 675 apparently normal small mammals and birds from the Invermay farm and nearby rubbish tip with the following prevalence rates: feral cats 27.8%, Norway rats 8.6%, mice 5.5%, hares 3.8% rabbits 1.9% ducks 5.3%, sparrows 2.3%, seagulls 2.3% and starlings 1.7%. For rabbits a significantly higher prevalence of infection was found in the autumn/winter period (4.8%) than the spring/summer period (0%). Insufficient numbers of other mammals were obtained to demonstrate any seasonal difference in prevalence. All bird isolations were obtained between March and July (8/158) compared with none from August to October (0/144). It appears that a number of free-living species of small mammal and birds may be reservoir hosts for Y. pseudotuberculosis and potential sources of infection for red deer on the Invermay farm.

Journal Article↗
PubMed1983

Modulation of hepatic insulin receptors by a human growth hormone fragment (hGH 6-13).

A synthetic amino-terminal fragment of human growth hormone (hGH) containing the sequence H2N-Leu-Ser-Arg-Leu-Phe-Asp-Asn-Ala-COOH (hGH 6-13) was shown to increase [125I]iodoinsulin binding to rat hepatic receptors in vivo. Analysis of the binding data indicated an increase in the capacity of the insulin receptors or the number of available receptors. In vitro experiments with isolated hepatocytes and hepatic plasma membranes revealed no direct interaction between the hGH 6-13 and the hepatic insulin receptors. When the isolated hepatocytes were preincubated with the synthetic hGH fragment (10 micrograms/ml) at 37 degrees C for 30 min prior to tests for insulin binding, the binding of [125I]iodoinsulin to the hepatic receptors was significantly enhanced. The variance between the in vivo and in vitro findings was considered in terms of the mechanism of hormonal actions mediated through a secondary cellular mediator.

Animals↗
PubMed1980

Glucose metabolism of human mononuclear cell subpopulations.

Previous studies have demonstrated metabolic dysfunction in the mononuclear cells of some children with abnormal cell-mediated immunity. Interpretation of these observations has been complicated by the extreme heterogeneity of cell types examined. The glycolytic metabolism of relatively enriched T-cells, non-T mononuclear cells (NTM), non-T lymphocytes (NTL), and monocytes was studied in an attempt to measure the metabolism of subpopulations of mononuclear cells. Lactate production by monocytes was 11 times greater than that of T-cells and 2 1/2 times greater than that of non-T lymphocytes. Exposure to phytohemagglutinin (PHA) stimulated glycolytic metabolism in T-cells but did not stimulate glucose utilization or lactate production in NTM. Even when T-cells were maximally stimulated by PHA, their observed metabolism was still lower than that of NTL. The ATP content of T lymphocytes and NTL was similar and was constant under the conditions of incubation. The initial ATP content of monocytes was higher than that of lymphocytes, and diminished during incubation. Tricarboxylic acid cycle activity did not contribute significantly to ATP synthesis in any of the mononuclear cell subpopulations, under the conditions of incubation used in this study. Significant hexose monophosphate shunt activity was observed in all mononuclear cell types. These studies demonstrate major metabolic differences between mononuclear cell subtypes. Any correlation of metabolic observation with clinical dysfunction of mononuclear cells requires the study of relatively pure cell populations.

Adult↗
PubMed1979

Neonatal mononuclear cell metabolism: further evidence for diminished monocyte function in the neonate.

The metabolic capacity of neonatal monocytes was compared to the metabolic capacity of adult monocytes by two entirely different methods: the selective diminution of monocyte contamination of whole mononuclear cells and the isolation of relatively purified populations of monocytes. Monocyte removal from whole mononuclear cells produced a diminution in the pyruvate kinase (PK) activity (from 28.6 +/- 1.1 to 15.6 +/- 1.2 nmoles/min/10(7) cells) and an increase in adenosine triphosphate (ATP) content (from 7.9 +/- 1.0 to 9.5 +/- 0.8 nmoles/10(7) cells) in adult cells. No change in PK activity (from 13.5 +/- 1.3 to 14.0 +/- 1.3) was observed in cord cells, but the ATP content of cord cells was higher after monocytes depletion (from 4.7 +/- 0.5 to 6.2 +- 0.7). The suggestion of metabolic vulnerability was confirmed by metabolic analysis of isolated adult and cord monocytes. The PK activity of adult monocytes was greater than that of cord monocytes (57 +/- 9 and 25 +/- 0.3, respectively) and the ATP content of adult monocytes (5.7 +/- 0.2) was greater than that of cord monocytes (2.3 +/- 0.1). The data confirm prior observations of diminished energy metabolism in neonatal mononucler cells and suggest that the metabolic perturbations may, in part, correlate with functional immaturity of the neonatal monocyte.

Adenosine Triphosphate↗
PubMedDate not supplied

Effect of mecillinam on peptidoglycan synthesis during the division cycle of Salmonella typhimurium 2616.

The effects of mecillinam, ampicillin and cephalexin on peptidoglycan synthesis in Salmonella typhimurium 2616 have been studied at equivalent concentrations or "isoactivities". Using antibiotics at isoactivities allows a direct comparison of the biochemical effects of different antibiotics. When mecillinam was added at different times during the division cycle at a concentration that produced 50% inhibition of peptidoglycan synthesis in an exponential culture over a short period of time, the inhibition of synthesis was greatest in the newborn cells and least in the dividing cells. Antibiotic competition experiments showed that mecillinam preferentially bound to penicillin-binding protein 2 in S. typhimurium 2616. High performance liquid chromatography analysis of the residual peptidoglycan synthesized in the presence of mecillinam showed an unexpected increase in pentapeptides and a significant increase in cross-linking. Other antibiotics added at equivalent activities did not show an increase in cross-linking.

Amdinocillin↗