Search PubMed⌕ Search

Biomedical subjects

R Mendez

Publications and source records attributed to R Mendez.

At least 19 recordsLinked to original sources
PubMed1992

Hyperacute and acute kidney graft rejection due to antibodies against B cells.

Because of the perception of its uncertain clinical significance, the B cell crossmatch is not universally performed before renal transplantation. Even though sporadic cases of hyperacute rejection associated with B cell antibodies have been reported, doubts remain in light of other studies suggesting no effect on graft survival. This report describes 4 cases of graft rejection (3 hyperacute and 1 acute) that occurred in patients with anti-B-cell antibodies specific against donor HLA-DR or DQ antigens. Absence of anti-donor class I antibodies was confirmed in all cases by 2-color flow cytometry. Strong evidence for an antibody-mediated mechanism was found in one patient with anti-class I and anti-class II antibodies in serum transplanted with a class II mismatched kidney. In this case, only anti-class II antibodies were recovered in the eluate of the nephrectomy specimen. These four cases were compiled from three different institutions over a four-year period, which confirms the infrequent occurrence of these events. While anti-class II antibodies may not always be detrimental for graft survival, these results also confirm that they have the potential to cause hyperacute or acute graft loss. We conclude that the information provided by the B cell crossmatch should be available at the time that a decision to proceed with a renal transplant is made.

Adult↗
PubMed1991

Characterization of cell-free protein-synthesis systems from undeveloped and developing Artemia embryos.

We have developed and characterized translationally active cell-free systems from Artemia embryos at different developmental times. The optimized lysates from 16 h-developed embryos incorporated radiolabelled amino acids into polypeptides for up to 120 min. The polypeptides synthesized ranged in Mr from 150,000 to 10,000, suggesting that the endogenous mRNA was capable of directing the synthesis of complete polypeptides. Similar results were obtained by using lysates from early developmental stages; even the cell-free system prepared from 1 h-developed embryos was partially active in protein synthesis. Furthermore, all these lysates were capable of re-initiation, as demonstrated by inhibition of initiation with the inhibitors edeine and 7-methylguanosine 5'-triphosphate. Because we found no endogenous protein-synthetic activity in the corresponding lysates from undeveloped embryos, we have used cell-free translation systems from 0 h- and 16 h-developed Artemia embryos to analyse the mechanisms limiting protein synthesis at very early developmental stages. Undeveloped-embryo lysates supplemented with nuclease-treated reticulocyte lysate were capable of translating endogenous mRNAs to give products with a wide spectrum of Mr values, but lysates of 16 h-developed embryos supplemented in this way were not further stimulated. The nuclease-treated lysate appeared to be unnecessary 5 h after resumption of development. These results suggested that a component(s) limiting translation in the undeveloped-embryo lysate was provided by the nuclease-treated reticulocyte lysate, and that this component(s) no longer limited protein synthesis after development. In view of these results, partially fractionated reticulocyte lysates were tested for restoration of protein-synthetic activity in the undeveloped embryo lysate. A high-salt ribosomal wash devoid of ribosomal subunits, which is considered a crude polypeptide-initiation-factor preparation, also restored translation activity in the undeveloped embryo lysate and made it capable of directing the synthesis of both endogenous mRNAs and exogenous (globin) mRNA.

Animals↗
PubMed1991

HLA matching at a single kidney transplant center.

Over 1000 patients were analyzed in two different time intervals, 1978-1983 and 1984-1989; these corresponded to patient groups not treated with cyclosporine and treated with cyclosporine. Analysis of mismatching showed that there was a significant (P less than 0.05) longterm matching effect in the precyclosporine, era with 0 HLA-DR-mismatched recipients having a 9.5-year half-life compared with a 3-year half-life for the 2 HLA-DR-mismatched transplant recipients. The trend was similar for the cyclosporine-treated groups, but not significant. Risk factors for donor age and race of the recipient (P less than 0.05) were identified in the cyclosporine-treated group. Graft survival in the high-risk patient populations was 70% or better in the 0, 1 HLA-ABDR-mismatched groups as compared with less than 60% graft survival in the high-risk transplant recipients with 2-6 HLA-ABDR mismatches. In the cyclosporine era the HLA-ABDR 0, 1-mismatched patient groups showed a significantly better graft survival than was found in all other categories and at all time intervals analyzed. Matching is a way to ameliorate some of the high risk potential associated with less than optimal donor or recipients.

Age Factors↗