Engineering of Fc(1) and Fc(3) from human immunoglobulin G to analyse subclass specificity for staphylococcal protein A.

A system for production of recombinant Fc fragments of human IgG in Escherichia coli has been developed to allow for structural and functional studies of human Fc. The genes for the Fc fragments of human IgG subclasses 1 and 3, designated Fc(1) and Fc(3), were cloned from a human spleen cDNA library. The interactions to Staphylococcal protein A (SpA), a bacterial Fc receptor, that interacts with human IgG-Fc(1), but not with human IgG-Fc(3), were analyzed. To corroborate the involvement of amino acid residues in Fc, responsible for these differences in binding, two Fc variants were constructed; Fc(1(3)) and Fc(3(1)), each containing an isotypic dipeptide substitution. Production levels in E. coli of 1-10 mg/l of secreted Fc proteins, covalently linked as dimers, were routinely obtained. SpA-binding analyses of all four Fc variants using biosensor technology, showed that Fc(1) and Fc(3(1)) interact with SpA, while Fc(3) and Fc(1(3)) lack detectable SpA binding. The rendered SpA binding of the Fc variant Fc(3(1)), is concluded to result from the introduced dipeptide substitution (R435H, F436Y). The results demonstrate that the Fc expression system efficiently can be used in Fc engineering.

Fasting serum insulin levels in essential hypertension. A meta-analysis.

UNLABELLED: BACKGROUND--The role of insulin in the genesis of essential hypertension remains an area of intense controversy. Most clinical evidence suggests a definite association. Several pathophysiologic mechanisms have been proposed. However, current data remain disparate and contradictory. METHODS--Meta-analysis allows data pooling of primary study findings and subsequent integration into a statistically meaningful outcome. This method was used to study the relationship in euglycemic individuals between blood pressure and fasting serum insulin level, age, body mass index, and fasting plasma glucose level. RESULTS: -A significant correlation was demonstrated between fasting serum insulin concentration and both systolic blood pressure and diastolic blood pressure. Age and body mass index also revealed meaningful associations. The meta-analytic correlation between plasma glucose level and both systolic blood pressure and diastolic blood pressure failed to achieve significance. CONCLUSIONS--Data from a meta-analytic review examining fasting serum insulin levels in euglycemic individuals demonstrate a significant correlation with systolic and diastolic blood pressure. This study supports the role of hyperinsulinemia in the pathogenesis of essential hypertension.

Effect of pro-atrial natriuretic peptides 1-30, 31-67 and 99-126 on angiotensin II-stimulated aldosterone production in calf adrenal cells.

Pro-atrial natriuretic peptide (Pro-ANP) is a 126 amino acid peptide from which atrial natriuretic peptide (ANP) (99-126 amino acid) is derived. ANP has potent diuretic, natriuretic and vasodilatory peptides. ANP is also a potent direct and indirect inhibitor of aldosterone secretion. The N-terminus of the ANP prohormone containing the peptides 1-30 and 31-67 have been demonstrated to have diuretic, natriuretic and vasodilatory properties. Dispersed calf zona glomerulosa cells were incubated with angiotensin II (A-II) and increasing concentrations of the ANP, ProANP 1-30 and 31-67 to determine if their reported natriuretic activity was mediated through suppression of aldosterone secretion. ANP as reported by many investigators produced a dose-dependent and potent inhibition of A-II-mediated aldosterone secretion. The Pro-ANP 1-30 and 31-67 did not affect A-II-stimulated aldosterone secretion at any of the doses tested. This study shows that the reported natriuretic effect of the fragments is not mediated by inhibition of aldosterone secretion.

Importance of the iliopsoas muscle in soft-tissue surgery of hip deformities in cerebral palsy children.

Twenty cerebral palsy patients who had undergone soft-tissue surgery at the hip (adductor tenotomy, medial lengthening of the hamstrings) were compared with a matched group of another 20 patients with a similar age range and findings and with additionally performed iliopsoas release, 2 or more years after surgery. Extension deficits of the hip did not improve with the addition of iliopsoas release. Internal rotation deformities showed equal improvement in both groups; the influence of the iliopsoas procedure was not significant. Adduction deformities, as documented on roentgenograms of the hip, showed significant improvement, however. Postural anomalies were not essentially influenced by iliopsoas release. Hip dislocations and subluxations, as assessed by the CE angles, were positively influenced by additional iliopsoas release; however, more effective improvement was obtained with ischiocrural elongation.

Hypernephroma associated with multiple endocrine neoplasia type I: a case report.

We report a case of multiple endocrine neoplasia type I and hypernephroma. Parathyroid hyperplasia, adrenocortical hyperplasia, a nodular goiter, multiple lipomas, a chromophobe adenoma of the pituitary and hypernephroma had all been diagnosed previously. All but the last are features consistent with the diagnosis of multiple endocrine neoplasia type I (Wermer's syndrome). The association of multiple endocrine neoplasia type I and hypernephroma may represent a new manifestation of this pleiotropic syndrome.

Multiple Allele Approach to the Study of Genes in DROSOPHILA MELANOGASTER That Are Involved in Imaginal Disc Development.

The phenotypes of five different lethal mutants of Drosophila melanogaster that have small imaginal discs were analyzed in detail. From these results, we inferred whether or not the observed imaginal disc phenotype resulted exclusively from a primary imaginal disc defect in each mutant. To examine the validity of these inferences, we employed a multiple-allele method. Lethal alleles of the five third-chromosome mutations were identified by screening EMS-treated chromosomes for those which fail to complement with a chromosome containing all five reference mutations. Twenty-four mutants were isolated from 13,197 treated chromosomes. Each of the 24 was then tested for complementation with each of the five reference mutants. There was no significant difference in the mutation frequencies at these five loci. The stage of lethality and the imaginal disc morphology of each mutant allele were compared to those of its reference allele in order to examine the range of defects to be found among lethal alleles of each locus. In addition, hybrids of the alleles were examined for intracistronic complementation. For two of the five loci, we detected no significant phenotypic variation among lethal alleles. We infer that each of the mutant alleles at these two loci cause expression of the null activity phenotype. However, for the three other loci, we did detect significant phenotypic variation among lethal alleles. In fact, one of the mutant alleles at each of these three loci causes no detectable imaginal disc defect. This demonstrates that attempting to assess the developmental role of a gene by studying a single mutant allele may lead to erroneous conclusions. As a byproduct of the mutagenesis procedure, we have isolated two dominant, cold-sensitive mutants.