UNLABELLED: To further study the interactions between innate and adaptive immunity in xenotransplantation, we explored the relative contribution of T-cell subsets in vascularized (heart) and cellular (islets) xenografts in a model with established xeno-non-reactivity of the innate system. MATERIALS: Specific innate xenotolerance was induced in xenoheart (hamster) recipients (nude rats) by a tolerizing regimen (TR), consisting of donor antigen infusion, temporary natural killer (NK)-cell depletion and a 4-week administration of leflunomide. Hamster pancreatic islets were transplanted either 1 week after heart transplantation or alone and syngeneic T-cell adoptive transfer was performed 10 days later. Purified CD3(+), CD4(+), and CD8(+) T cells were given 2 weeks after withdrawal of all drugs. At the day of rejection, xenografts were removed for histology. Serum was taken and IgM and IgG xenoantibody titers were measured by flow cytometry. RESULTS: Both heart and islet grafts were rejected after CD4(+) reconstitution. After CD8(+) T-cell adoptive transfer, cellular grafts were not rejected but vascularized grafts were rejected, although only after several months. Rejection in CD4(+) reconstituted nude rats was accompanied by the generation of predominantly IgG xenoantibodies. CONCLUSION: CD4(+) T lymphocytes are able to rapidly initiate the rejection of islet xenografts in the presence of a xenotolerant innate immune system either by breaking the "innate tolerance" (e.g., by activating macrophages and NK-cells) or through a mechanism without any involvement of the innate tolerance (e.g., T-dependent IgG antibody production). In contrast, CD8(+) T cells provoke a late rejection of only xenoheart grafts.

Animals↗

PubMedDate not supplied

Intestinal allografts delay rejection and prolong survival of combined donor-specific and third party solid organ transplants.

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Anastomosis, Surgical↗

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3-D imaging and stereotactic radiosurgery.

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Artificial Intelligence↗

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The matrix metalloprotease pump-1 (MMP-7, Matrilysin): A candidate marker/target for ovarian cancer detection and treatment.

Matrix metalloproteases are known to play an important role in tumor invasion by mediating degradation of extracellular matrix. In this study, we have investigated the expression of the matrix metalloprotease pump-1 gene (also referred to as MMP-7, Matrilysin) in 44 ovarian tumors (12 low malignant potential tumors, 32 carcinomas) and 10 normal ovaries using quantitative PCR. The PCR product was labelled with 32P and a phosphoimager was used to determine the relative expression of pump-1 compared to an internal control beta-tubulin. mRNA expression levels of pump-1 were significantly elevated in 9 of 12 low malignant potential tumors and 26 of 32 carcinomas. Northern blot hybridization showed that the 1. 1-kb pump-1 transcript was abundant in carcinoma but seldom expressed in normal adult tissues including normal ovary. Immunohistochemical localization of the pump-1 protein confirms its expression by ovarian tumor cells. Our results suggest that pump-1 is frequently overexpressed in ovarian tumors and may contribute to its invasive nature or growth capacity, therefore pump-1 may serve as a useful marker for early detection of disease and/or a target for therapeutic intervention in downregulation of tumor progression.

Biomarkers, Tumor↗

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Kidney is the only source of human plasma renin in 45-kb human renin transgenic mice.

Prorenin is expressed in certain extrarenal tissues, but normally only the kidneys process prorenin to renin and secrete renin into the circulation. Although transgenic animal lines containing the human renin (hREN) structural gene with either 0.9-kb or 3-kb 5'-flanking DNA express the transgene appropriately in renal juxtaglomerular cells and secrete hREN into the circulation, the source of the circulating renin is not known. In the present study, we observed that 13-kb hREN transgenic mice that contain the structural gene and 0.9-kb 5'-flanking DNA express hREN mRNA in many unusual tissues. We also observed that circulating hREN levels in 13-kb hREN mice increased after bilateral nephrectomy. These results suggested that the hREN gene is expressed at inappropriate locations where prorenin might be processed to renin. To determine if more distal sequences flanking the hREN gene might contribute to cell and tissue specificity, we used a 45-kb hREN genomic fragment that contained the structural gene and about 25-kb 5'- and 8-kb 3'-flanking DNA sequences to generate 3 separate transgenic lines that contained the intact transgene sequences. Ribonuclease protection assays revealed a much narrower tissue distribution of hREN expression than in the 13-kb hREN transgenic mice. In each 45-kb hREN line, hREN mRNA was present only in the kidney, adrenal, lung, eye, ovary, and brain. Moreover, 24 hours after nephrectomy, human plasma renin fell to very low levels, indistinguishable from those of nontransgenic littermates, indicating that their circulating hREN is of renal origin. These studies suggest that sequences flanking the structural gene, missing from previous hREN transgenic lines, suppress renin gene expression at inappropriate extrarenal sites where cellular proteases, to which prorenin is not normally exposed, could convert prorenin to renin, resulting in abnormal secretion of renin into the plasma.

Animals↗

PubMedDate not supplied

Processing sites are different in the generation of HLA-A2.1-restricted, T cell reactive tumor antigen epitopes and viral epitopes.

In order to improve the processing efficiency of T cell tumor antigen epitopes, this bioinformatic study compares proteolytic sites in the generation of 47 experimentally identified HLA-A2.1-restricted immunodominant tumor antigen epitopes to those of 52 documented HLA-A2.1-restricted immunodominant viral antigen epitopes. Our results show that the amino acid frequencies in the C-terminal cleavage sites of the tumor antigen epitopes, as well as several positions within the 10 amino acid (aa) flanking regions, are significantly different from those of the viral antigen epitopes. In the 9 amino acid epitope region, frequencies differed somewhat in the secondary-anchored amino acid residues on E3 (the third aa of the epitope), E4, E6, E7 and E8; however, frequencies in the primary-anchored positions, on E2 and E9, for binding in the HLA-A2.1 groove, remained almost identical. The most frequently occurring amino acid pairs in both N-terminal and C-terminal cleavage sites in the generation of tumor antigen epitopes were different from those of the viral antigen epitopes. Our findings demonstrate for the first time that these two groups of epitopes may be cleaved by distinct sets of proteasomes and peptidases or similar enzymes with lower efficiencies for tumor epitopes. In the future, in order to more effectively generate tumor antigen epitopes, targeted activation of the immunoproteasomes and peptidases that mediate the cleavage of viral epitopes could be achieved, thus enhancing our potential for antigen-specific tumor immunotherapy.

Antigens, Neoplasm↗

PubMedDate not supplied

Analysis of flavonoids in Semen Cuscutae by micellar electrokinetic chromatography and high-performance liquid chromatography.

Five different flavonoids in Semen Cuscutae were determined for the first time by micellar electrokinetic chromatography (MEKC) and reversed-phase high-performance liquid chromatography (RP-HPLC). MEKC was carried out on a 68.5-cm fused-silica capillary using 0.035 mol/L sodium dodecyl sulfate and 0.02 mol/L borate-phosphate (pH 7.0) containing 10% methanol as the running buffer. RP-HPLC was performed on a 12.5-cm Hypersil C18 (Agilent Technologies, Palo Alto, CA, U.S.A.) column with a 0.025-mol/L phosphate acid (A) - methanol (B) solvent gradient. Both MEKC and HPLC are rapid, simple, and efficient. The results obtained using these techniques are compared. MEKC and HPLC can be complementary to each other for the quality control of Semen Cuscutae.

Calibration↗

PubMedDate not supplied

[Effects of nitric oxide on cardioprotection prior to ischemia-reperfusion].

This study aimed at evaluating the role of nitric oxide (NO) when generated 24 h prior to ischemia-reperfusion. Three groups were studied in an isolated buffer-perfused heart model: Control (saline = 3.3 mL/kg, n = 10), the precursor of NO, L-arginine, (500 mg/kg, n = 10) and an inhibitor of NO synthase, L-NAME, (10 mg/kg, n = 9). All groups were injected intraperitoneally 24 h before heart extraction. Nitrites, nitrates (an index of nitric oxide release) and cardiac troponine I were assayed. During the reperfusion period, there was a low release of nitric oxide and cardiac troponine I associated with improved recovery of post-ischemic myocardial function. These results indicate that in this model, the pre-treatment improved myocardial function and thus, NO could play a role as a trigger and not as a mediator of cardioprotection.

Animals↗