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J R Thomas

Publications and source records attributed to J R Thomas.

At least 109 records · Page 6Linked to original sources
PubMed1993

The flood of '93.

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Disasters↗
PubMed1993

Immediate versus delayed repair of skin defects following resection of carcinoma.

Facial defects resulting from excision of skin malignancies may be reconstructed with flaps or grafts immediately or in delayed fashion, or the wound may be allowed to heal by secondary intention. The merits of each option are discussed along with a brief review of the pertinent details of wound healing. A small delay in reconstruction of up to 3 to 4 days can be tolerated safely with no compromise of results. When healing by secondary intention is chosen, fenestration speeds coverage of the wound, and moist dressings with antibiotic ointment effectively prevent infection and expedite epithelialization.

Carcinoma↗
PubMed1992

Refined structure of the lipophosphoglycan of Leishmania donovani.

The primary structure of the major surface glycoconjugate of Leishmania donovani parasites, a lipophosphoglycan, has been further characterized. The repeating PO4-6Galp beta 1-4Man disaccharide units, which are a salient feature of the molecule, are shown to terminate with one of several neutral structures, the most abundant of which is the branched trisaccharide Galp beta 1-4(Manp alpha 1-2)Man. The phosphosaccharide core of lipophosphoglycan, which links the disaccharide repeats to a lipid anchor, contains 2 phosphate residues. One of the core phosphates has previously been localized on O-6 of the galactosyl residue distal to the lipid anchor; the second phosphate is now shown to be on O-6 of the mannosyl residue distal to the anchor and to bear an alpha-linked glucopyranosyl residue. Also, the anomeric configuration of the unusual 3-substituted Galf residue in the phosphosaccharide core is established as beta. The complete structure of the core is thus PO4-6Galp alpha 1-6Galp alpha 1-3Galf beta 1-3[Glcp alpha 1-PO4-6]Manp alpha 1-3Manp alpha 1-4GlcN alpha 1-. This further clarification of the structure of lipophosphoglycan may prove beneficial in determining the structure-function relationships of this highly unusual glycoconjugate.

Animals↗
PubMed1992

Purification and characterization of an extracellular phosphoglycan from Leishmania donovani.

An extracellular phosphoglycan (exPG), present in the culture medium of the promastigote form of Leishmania donovani, was purified and structurally characterized. The purification scheme included ethanol precipitation of the culture medium, anion exchange chromatography, hydrophobic chromatography on phenyl-Sepharose, and preparative polyacrylamide gel electrophoresis. Structural analysis by 1H-1H NMR, methylation linkage analysis, and glycosidase digestion revealed that the exPG consisted of the following structure: (CAP)----[PO4-6Galp beta 1-4Manp alpha 1]10-11-PO4-6Galp beta 1-4Man. The cap was found to be one of several small, neutral oligosaccharides, the most abundant of which was the trisaccharide Galp beta 1-4(Manp alpha 1-2)Man. The results indicated structural analogy to the cellular-derived lipophosphoglycan (LPG) from L. donovani. The important exceptions are a lack of the lipid anchor, the entire phosphosaccharide core, and several of the repeating disaccharide units. Although the function of exPG is presently unknown, it may play a protective role for the promastigote in the insect vector or during infection of a mammalian host.

Animals↗
PubMed1992

Relative effects of intraoperative tissue expansion and undermining on wound closing tensions.

Intraoperative tissue expansion is advocated as a technique to facilitate closure of soft-tissue wounds with less tension than if they were closed primarily without expansion or, presumably, simple undermining. Few objective studies have been done, however, to validate the technique. We specifically questioned the relative effects of intraoperative tissue expansion and undermining on wound closing tensions in an animal model. Our data showed statistically significant reduction in the force required to close a wound after acute intraoperative tissue expansion when compared with baseline. However, when the degree of undermining achieved by the expander was matched in an equivalent defect, no difference in the resultant wound closing tensions could be discerned between techniques. This study should be viewed as an initial effort to understand the role of intraoperative tissue expansion in reconstructive surgery.

Animals↗
PubMed1992

Tyrosine pretreatment alleviates suppression of schedule-controlled responding produced by corticotropin releasing factor (CRF) in rats.

Disruption of performance observed when animals are exposed to physical stressors which deplete brain catecholamines can be alleviated by pretreatment with the catecholamine precursor tyrosine. Central administration of the stress hormone corticotropin releasing factor (CRF) has been shown to affect a variety of behaviors and also to potently increase the release of central catecholamines. Since CRF-induced disruption of behavior may involve CRF-induced depletion of brain catecholamines, the present study examined whether tyrosine would alleviate suppression of schedule-controlled responding in rats resulting from ICV administration of CRF. Administration of CRF (1.0 microgram-10 micrograms) produced dose-dependent suppression of response rate and total number of earned reinforcers in rats responding on a multiple fixed-interval 60 s/fixed-ratio 20 schedule for food reinforcement. Pretreatment with 200 mg/kg tyrosine (IP) administered with ICV saline decreased response rate but did not lower total reinforcers, whereas 400 mg/kg of tyrosine decreased both. Injection of 400 mg/kg tyrosine reduced, but did not completely restore, CRF-induced suppression of behavior. The 200 mg/kg tyrosine dose was less effective in alleviating CRF-induced suppression of performance. These data indicate that pretreatment with the catecholamine precursor tyrosine can partially ameliorate performance decrements resulting from CRF administration.

Animals↗
PubMed1992

Radioiodinated 2-hydroxy-3-(4-iodophenyl)-1-(4-phenylpiperidinyl)propane: potential radiotracer for mapping central cholinergic innervation in vitro.

Radioiodinated 2-hydroxy-3-(4-iodophenyl)-1-(4-phenylpiperidinyl)propane, 5 (4-HIPP), was synthesized and evaluated as a simple vesamicol-like radiotracer for mapping cholinergic pathways in the brain. Both enantiomers of 5 exhibit significant accumulation (approx. 2% of injected dose) and prolonged retention (t1/2 greater than 3 h) within the rat brain. The accumulation of radioiodinated 5 in the rat brain was reduced by up to 70% in the presence of vesamicol and its analogs. The levorotary isomer (-)-4-[123I]HIPP exhibits significant accumulation in the monkey brain, with a half-life of about 9 h. Radioiodinated 5 may therefore be a useful tool for studying cholinergic pathways in the brain.

Animals↗
PubMed1992

Role of leukocyte CD11/CD18 complex in endotoxic and septic shock in rabbits.

Two models of sepsis were investigated using rabbits. In the first model, rabbits given lipopolysaccharide (LPS) were treated with saline (group II) or CD18 monoclonal antibody (MAb) 60.3 (group III). Group I animals received no LPS. Cardiac output was maintained by infusion of lactated Ringer solution with group II (95 +/- 68 ml/kg) requiring significantly more than group I (0 +/- 0 ml/kg) or group III (39 +/- 27 ml/kg). Lung permeability indexes in groups II (median 0.002, range 0.023) and III (median 0.0035, range 0.053) were not different but were significantly greater than group I (median 0.0007, range 0.001). In the second model, peritonitis was produced by devascularizing the appendix, leaving it in situ for 19 h, and then performing an appendectomy. Saline or MAb 60.3 treatment was at appendectomy and every 12 h for 3 days. Survival was significantly greater in the MAb 60.3-treated group at day 10 (90 vs. 40%). Lung permeability was increased at day 2 and was not different between groups. Day 1 fluid requirements were greater in the saline-treated group. These data are consistent with MAb 60.3 protection of systemic but not pulmonary circulation in two models of sepsis.

Animals↗
PubMed1992

Scurvy in a nonalcoholic person in the United States.

Scurvy is rarely diagnosed in our society today. The authors describe the case of a 31-year-old man with weakness, gingival pain, and a rash over the lower extremities. He had a history of poor nutritional intake, no alcohol consumption, and a 13 pack-year history of cigarette smoking. Laboratory studies revealed an extremely deficient serum ascorbic acid level. Treatment was begun with oral ascorbic acid tablets and, within 3 days after discharge, all clinical symptoms of scurvy had resolved. Scurvy is an easily treated disease and should be considered when there is an appropriate history and classic clinical findings. Because vitamin C deficiency can be seen in many chronic disease states, it is important to recognize some of the early features and clinical manifestations of such nutritional deficiencies.

Adult↗