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Biomedical subjects

D G Tice

Publications and source records attributed to D G Tice.

At least 19 recordsLinked to original sources
PubMed1997

Survival of rat small bowel allografts treated with allotrap 07R.

Previous reports from other investigators demonstrate prolongation of allogeneic heart graft survival and decrease in CTL responses in rats treated with a small synthetic peptide corresponding to residues 75-84 of the human HLA-B7-01 molecule (Allotrap 07R). We wished to determine the efficacy of these peptides in the highly immunogenic ACI > LEW and LEW > ACI small bowel transplant models. Animals were divided into treatment groups: I, none; II, Allotrap (20 mg/kg/day on Days 0-4); III, cyclosporine (CsA; 10 mg/kg/day on Days 0-4); IV, Allotrap + CsA (as in groups II and III); V, Allotrap (40 mg/kg/day every other day on Days -19 to 4); VI, Allotrap + CsA (as in groups III and V); VII, Allotrap + CsA (as in groups III and V, with Allotrap administered intragraft Days 0-4). The animals were sacrificed at the time of graft rejection (defined by dusky, necrotic stoma and increased stomal output). Peripheral blood, spleen, native bowel, and allograft intraepithelial and lamina propria lymphocytes were harvested and mixed lymphocyte culture (MLC) reactivity against self, donor, and third-party splenocytes was assessed. Statistical analysis was performed by ANOVA with Dunnett's t for multiple comparisons against a control as a post hoc test. We found a very slight, but significant prolongation of graft survival in with treatment protocol V for both strain combinations. In addition, MLC response of splenocytes to donor antigen was decreased with combined CsA and Allotrap, but not with Allotrap alone. We conclude that Allotrap decreases response to alloantigens, and slightly, but significantly prolongs graft survival in the hihgly immunogenic small bowel transplant model.

Animals↗
PubMed1997

Role of nitric oxide and tumor necrosis factor on lung injury caused by ischemia/reperfusion of the lower extremities.

PURPOSE: Acute aortic occlusion with subsequent ischemia/reperfusion (I/R) of the lower extremities is known to predispose to lung injury. The pathophysiologic mechanisms of this injury are not clear. In the present study, we studied the role of tumor necrosis factor (TNF) and nitric oxide (NO) in lung injury caused by lower extremity I/R. METHODS: A rat model in which the infrarenal aorta was cross-clamped for 3 hours followed by 1 hour of reperfusion was used. The rats were randomized into five groups: group 1, aorta exposed but not clamped; group 2, aorta clamped for 3 hours, followed by 1 hour of reperfusion; group 3, 1 mg/kg dexamethasone administered before the aorta was clamped; group 4, 25 mg aminoguanidine, a specific inducible NO synthase (iNOS) inhibitor, administered before the aorta was clamped; and group 5, 2 mg/kg TNFbp, a PEG-ylated dimeric form of the high-affinity p55 TNF receptor I (RI), administered before the aorta was clamped. NO concentration in the exhaled gas (ENO) was measured, as an index of NO production by the lung, in 30 minute intervals during I/R. Serial arterial blood samples for TNF assay were obtained during the course of the experiment. At the end of the experiment, the lungs were removed and histologically examined for evidence of injury. RESULTS: ENO in group 2 increased from 0.7 +/- 0.3 ppb at baseline to 54.3 +/- 7.5 ppb at the end of ischemia and remained stable during reperfusion (54.6 +/- 8.5 ppb at the end of reperfusion). ENO production was blocked by aminoguanidine, by dexamethasone, and by TNFbp given before aortic occlusion. Serum TNF in groups 2, 3 and 4 increased rapidly during early ischemia, reaching its peak value 60 minutes after occlusion of the aorta, then gradually declined to baseline levels at the end of ischemia, and remained low during reperfusion. TNFbp decreased serum TNF concentration significantly when it was given before aortic occlusion. Histologic examination of the lungs at the end of the experiment revealed that aminoguanidine, dexamethasone, and TNFbp had a protective effect on the lungs. CONCLUSIONS: Serum TNF increases rapidly during lower extremity ischemia and causes increased production of NO from the lung by upregulating iNOS. Increased NO is associated with more severe lung injury, and iNOS blockade has beneficial effects on the lung. TNF blockade before ischemia decreases NO production by the lung and attenuates lung injury. ENO can be used as an early marker of lung injury caused by lower extremity I/R.

Animals↗
PubMed1988

The T-lymphocyte colony-forming cell (T-CFC): in vitro studies of progenitors and progeny.

The lineage of T-lymphocyte colony-forming cells (T-CFC) and the phenotype of the progeny of T-CFC have not yet been well-defined. To characterize the progenitor cells and progeny of the T-CFC, we separated normal human peripheral blood lymphocytes into enriched lymphocyte subpopulations, stimulated with various mitogens and cultured in a semisolid agar system. After 5 days, the number of colonies was counted, and the presence of CD4+ and CD8+ cells was determined in situ with FITC-conjugated monoclonal antibodies. Plating of B cells provided the lowest, T cells an intermediate and null cells the highest number of T-cell colonies (P less than 0.05). CD4+ and CD8+ cells produced equivalent numbers of T-cell colonies. T-cell colonies consisted of either CD4+ or CD8+ cells; mixed-cell colonies were rarely present. Plating of CD4+ or CD8+ cells produced both CD4+ and CD8+ colonies. We conclude that T-CFC exist in the CD4+, CD8+ and null-cell populations. In addition, T-CFC give rise to T-cell colonies possessing either CD4+ or CD8+ determinants.

B-Lymphocytes↗
PubMed1987

Serum from patients with non-Hodgkin's lymphoma (NHL) inhibits T-cell colony formation.

This study compared T-cell colony formation in soft agar of lymphocytes from the peripheral blood and lymph nodes of patients with non-Hodgkin's lymphoma (NHL) with T-cell colony formation of peripheral blood lymphocytes from normal individuals. Mononuclear cells were separated from other blood and lymph node elements on density gradient columns, phenotyped for T- and B-cell antigens using monoclonal antibodies, and then plated in soft agar cultures. Lymphocytes from peripheral blood and lymph nodes of patients with NHL exhibited less T-cell colony formation (p less than 0.01) than did lymphocytes from normal individuals. This decrease in T-cell colony formation was not the result of the number of T cells or null cells plated, or differences in proportions of T helper and T suppressor cells. However, when sera from patients with NHL were incubated with normal lymphocytes before plating in soft agar, a decrease in number of T-cell colonies was observed (p less than 0.01). We conclude that peripheral blood and lymph node mononuclear cells from patients with NHL have a decreased ability to form T-cell colonies in soft agar cultures and that this decrease is related, at least in part, to the presence of serum factor(s).

Agar↗
PubMed1986

T lymphocyte colonies are the progeny of single cells.

T lymphocyte colonies, arising from phytohemagglutinin (PHA) stimulated mononuclear cells cultured in a semi-solid agar matrix, could be the progeny of single cells (monoclonal) or of multiple cells (polyclonal). We have conducted several studies to determine if these colonies are monoclonal or polyclonal in origin. Normal human peripheral blood mononuclear cells from male-female, HLA-A and B disparate donor pairs were incubated for 18 h in RPMI 1640 containing PHA and fetal calf serum (FCS) and then cultured in a two-layer semi-solid agar system. After 5 days of incubation, the clonality of the colonies was assessed by in situ Y chromatin analysis, and by analysis of HLA-A and B locus antigens. Overlayers were stained with quinicrine dihydrochloride and the number of cells in the T cell colonies with Y chromatin enumerated using fluorescence microscopy. In other studies, colonies were picked from the agar with a capillary pipette and expanded in culture media. After 17 days of culture, cells were harvested and HLA-A and B phenotypes were determined. The results indicate that 87% of the T cell colonies had cells of either male or female origin. In addition, 90% of the colonies possessed HLA-phenotypes of only one donor. We conclude that Y chromatin and HLA analysis of individual colonies from cocultures suggest the monoclonality of T lymphocyte colonies.

Adult↗