Structural studies on endothelin receptor subtype B specific agonist IRL 1620 (suc-[Glu9,Ala11,15]ET-1(8-21)) and its analogs with dipalmitoyl phosphatidylcholine vesicles by NMR spectroscopy

IRL 1620 {suc-[Glu⁹,Ala^11,15]ET-1(8-21)} is a potent and specific agonist for the ET_B receptor. Five analogs of IRL 1620 were synthesized in this study. These were all C-terminal linear peptides of endothelin 1 (ET-1) comprising 14 amino acid residues and exhibiting highly potent ET_B receptor binding affinities. The peptides consisted of three pairs and each component of the pairs differed from its partner in only the 18th residue, i.e. Asp was replaced by Gly. The replacements resulted in more than a 10-fold increase in affinity to the ET_A receptor. The structures of these peptides were investigated in the presence of phospholipid vesicles (dipalmitoyl phosphatidylcholine) by NMR spectroscopy. By the replacement of Asp by a less bulky Gly, the C-terminal tripeptide region folded back toward the helical region, making it shorter than the Asp-substituted peptide helical region. Such a folded conformational feature may explain the increased binding affinity to ET_A receptor.     

Recurrence of renal cell carcinoma more than 5 years after nephrectomy

OBJECTIVES: We evaluated clinical features and predictive factors for the recurrence of renal cell carcinoma (RCC) developing more than 5 years after nephrectomy. METHODS: We retrospectively reviewed 239 patients with RCC who underwent surgery for the primary lesion. To identify factors that affected recurrence more than 5 years after nephrectomy (delayed recurrence) and its clinical outcomes, we performed a multivariate analysis using Cox's proportional hazards model and a survival study. RESULTS: Recurrence developing within 5 years after nephrectomy (early recurrence) was found in 57 patients and delayed recurrence in 11 patients. The multivariate analysis revealed no clinical and pathologic features influencing delayed recurrence in 114 patients who survived more than 5 years after nephrectomy without having early recurrence. The patients with delayed recurrence showed better clinical outcomes than those with early recurrence when the rate was determined from the time of recurrence. CONCLUSIONS: Although delayed recurrence is not a rare event for patients with RCC, no clinical and pathologic factors at the time of the initial treatment can predict the recurrence. Patients who are free of recurrence for more than 5 years after surgery for a primary lesion should be carefully followed up for delayed recurrence.     

Indirect hemagglutination assay for antibodies to Escherichia coli lipopolysaccharides O157, O111 and O26 in patients with hemolytic uremic syndrome

We examined sera from 10 patients with hemolytic uremic syndrome (HUS) and 51 controls, with and without diarrhea, for antibodies to Escherichia coli lipopolysaccharides (LPS) O157, O111 and O26 using the indirect hemagglutination (IHA) assay. A significant rise (to a titer of ≥ 2560) in IHA antibody to O157 LPS was detected in eight of the 10 HUS patients, to O111 in two patients, one of whom showed concomitantly an antibody rise to O157, but to O26 in no patients. The IHA titers fell rapidly after the acute phase of the illness. Of the control sera 15 (29.4%) non-specifically agglutinated uncoated sheep red blood cells (SRBC) at a titer of ≥80, six (3.9%) at ≥320 and the maximum was 640. In spite of the relatively low level of non-specific agglutination the IHA appeared to be a useful screening method to identify verotoxin-producing E. coli infections at the early stage of HUS because the titers were clearly higher than non-specific agglutination and the assay is easy to perform and gives results quickly. Artificial carriers are being considered for use in place of SRBC to diminish the non-specific hemagglutination.