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Biomedical subjects

N Bilgin

Publications and source records attributed to N Bilgin.

At least 163 records · Page 9Linked to original sources
PubMed1991

Treatment of steroid-resistant renal allograft rejection with OKT-3 and plasmapheresis.

The murine monoclonal antibody (OKT-3) and plasmapheresis therapy were applied in combination to treat acute renal allograft rejection in 31 patients who were not responsive to conventional bolus steroid treatment. Six of them were living related but ABO incompatible; another 25 patients were ABO compatible (1 was from a cadaver, 7 were from living unrelated donors, and 17 were from living related donors). Of these 31 patients, 25 (80.65%) showed perfect improvement in their graft function. These 25 patients had a mean follow-up time of 8 months, and had mean creatinine values of 1.2 mg% (0.8-2.8 mg%). It is concluded that OKT-3 and plasmapheresis combination therapy is very effective in reversing steroid-resistant rejections in high-risk patients such as ABO-incompatible cases.

Adolescent↗
PubMed1991

ABO-incompatible kidney transplantation with donor-specific skin graft.

From November 3, 1975, to May 31, 1989, 711 (548 living-related and 163 cadavers) kidney transplantations were performed in our centers. In the final 2 years, 15 ABO-incompatible living related kidney transplantations were performed. In 4 cases, the recipient's blood groups was O and the donor's A1. In 3 cases the blood group of the recipient was A1 and the donor's AB, two patients were B with the donors A1 and the other 2 were O with donors B. The other 3 recipients group was B and the donors' were AB. The donors' and recipients' HLA-AB typing showed one haplotype matching in 12 and two haplotypes matching in 3 patients. The donors were mothers in 7 cases, sibling in 5, and father in 3 cases. At least 3 weeks before the renal transplantation, donor-specific skin grafts and subsequently splenectomy were performed on 9 recipients, but on 6 recipients without splenectomy. Following the skin graft, cross-match was done starting from the 15th day and then continued every week. The immunosuppression, which consisted of triple drugs (0.5 mg/kg prednisolone, 2 mg/kg cyclosporin-A and 2 mg/kg azathioprine) was followed by skin graft. Renal transplantation was performed according to cross-match and skin graft results, and all recipients prior to surgery received at least two sessions of plasmapheresis. Regular dose of immunosuppression that included triple drugs were used after the kidney transplantation and then Orthoclone OKT-3 and plasmapheresis were applied during the rejection episodes without bolus therapy. All patients were followed for 5 to 24 months (ave. 14,13 months).(ABSTRACT TRUNCATED AT 250 WORDS)

ABO Blood-Group System↗
PubMed1990

Binding of periodate-oxidized guanine nucleotides to eukaryotic elongation factor 2.

Periodate-oxidized guanine nucleotides (GTPox and GDPox) were shown to bind stoichiometrically to rat liver elongation factor 2 (EF-2). This binding was quantitatively inhibited in the presence of GTP. After binding, oxidized nucleotides remained on EF-2 despite extensive dialysis. They exchanged, however, with free quanine nucleotides in the course of prolonged (greater than 1 h) incubations. The prior reduction EF-2.GTPox with NaBH4 abolished, to a large extent, this slow exchange. Thus, a Schiff's base was implicated to be formed between EF-2 and oxidized guanine nucleotides. Mg2+ increased the GTPox concentration necessary for a stoichiometric binding to EF-2. EF-2-oxidized nucleotide conjugates bound in the presence of ribosomes a second molecule of GTP (or GTPox). GTPox bound to EF-2 in the presence of ribosomes appeared to exchange readily with free GTP. Moreover, GTPox proved to be active as substrate in EF-2 and ribosome-dependent GTPase reaction: Km values found for GTPox and GTP were 7.7 and 3.4 microM, respectively. The binding of GTPox to EF-2 inhibited only partially the subsequent ribosome-dependent GTP binding, and GTPase reaction or polyphenylalanine (polyPhe) synthesis. On the other hand, the binding of GuoPP[CH2]Pox to EF-2 inhibited all of these reactions strongly. The nature of the binding site involved in the direct interactions of EF-2 with guanine nucleotides is discussed in the light of these results.

Animals↗
PubMed1990

Impaired in vitro kinetics of EF-Tu mutant Aa.

The kirromycin-resistant EF-Tu mutant Aa, previously shown to be an antisuppressor for nonsense and missense suppressor tRNAs, has been characterised in a poly(U)-primed translation system in vitro. Two major defects were found in the function of the mutant. First, the dissociation constant for Aa binding to Phe-tRNA(Phe) was increased tenfold compared to wild-type EF-Tu. Second, kcat/Km for the interaction between the EF-Tu.GTP.aa-tRNA complex and the ribosome was decreased by the mutation to one third of its wild-type value. No differences were observed between mutant and wild-type factor in the regeneration of EF-Tu.GTP from EF-Tu.GDP via EF-Ts or in the mistranslation frequency by Leu-tRNA(4Leu). The relation between the in vitro results and the mutant phenotype in vivo is discussed.

Bacterial Proteins↗
PubMed1990

Mapping of catalytically important domains in Escherichia coli leader peptidase.

Leader peptidase (Lep) is a central component of the secretory machinery of Escherichia coli, where it serves to remove signal peptides from secretory proteins. It spans the inner membrane twice with a large C-terminal domain protruding into the periplasmic space. To investigate the importance of the different structural domains for the catalytic activity, we have studied the effects of a large panel of Lep mutants on the processing of signal peptides, both in vivo and in vitro. Our data suggest that the first transmembrane and cytoplasmic regions are not directly involved in catalysis, but that the second transmembrane region and the region immediately following it may be in contact with the signal peptide and/or located spatially close to the active site of Lep.

Amino Acid Sequence↗
PubMed1990

Ribosomal RNA and protein mutants resistant to spectinomycin.

We have compared the influence of spectinomycin (Spc) on individual partial reactions during the elongation phase of translation in vitro by wild-type and mutant ribosomes. The data show that the antibiotic specifically inhibits the elongation factor G (EF-G) cycle supported by wild-type ribosomes. In addition, we have reproduced the in vivo Spc resistant phenotype of relevant ribosome mutants in our in vitro translation system. In particular, three mutants with alterations at position 1192 in 16S rRNA as well as an rpsE mutant with an alteration of protein S5 were analysed. All of these ribosomal mutants confer a degree of Spc resistance for the EF-G cycle in vitro that is correlated with the degree of growth rate resistance to the antibiotic in culture.

Escherichia coli↗