The lumbar bone mineral density is affected by long-term poor metabolic control in adolescents with type 1 diabetes mellitus

AIM: To analyze whether bone mineral density (BMD) and bone resorption status are influenced by long-term metabolic control and duration of disease in adolescents with long-standing type 1 diabetes mellitus. METHODS: Twenty-seven adolescents (age 13.1 +/- 1.7 years, duration of diabetes 6.9 +/- 3.0 years) were studied. The BMD, expressed as z score, was measured at the lumbar spine (L1-L4) using dual-energy X-ray absorptiometry, while the urinary excretion of total deoxypiridinoline (Dpyd), a marker of bone resorption, was measured by immunoassay and was corrected by creatinine (Cr). Linear and multivariate correlations between lumbar BMD z score or Dpyd/Cr excretion and age and disease variables [short-term (Hb A(1c latest)) or long-term (Hb A(1c whole duration)) metabolic control, duration, 'diabetes impact index' (mean Hb A(1c whole duration) x duration of disease in months)] were sought. RESULTS: In diabetic subjects the mean BMD z score was -0.44 +/- (SD) 1.02 (95% CI: -0.03; -0.84), and the Dpyd/Cr excretion was not increased. A negative correlation was found between lumbar BMD z score and age (r -0.59; p = 0.001), duration (r -0.39; p = 0.04), and the diabetes impact index (r -0.4; p = 0.04). The Dpyd/Cr ratio correlated negatively with age (r -0.40; p = 0.04) and positively with height velocity (r 0.42; p = 0.04). By using multiple linear regression, age showed a significant inverse correlation with lumbar BMD z score (beta = -0.39; p = 0.0005). A negative correlation was found between lumbar BMD z score and Hb A(1c whole duration) (beta = -0.40; p = 0.02) or diabetes impact index (beta = -0.001; p = 0.01). CONCLUSIONS: Poor metabolic control may expose adolescents with long-standing type 1 diabetes to the risk of developing osteopenia in adult age. Optimization of metabolic control in growing diabetic children may prevent osteoporosis in later life.     

Unusual binding properties of the SH3 domain of the yeast actin-binding protein Abp1: structural and functional analysis

Abp1p is an actin-binding protein that plays a central role in the organization of Saccharomyces cerevisiae actin cytoskeleton. By a combination of two-hybrid and phage-display approaches, we have identified six new ligands of the Abp1-SH3 domain. None of these SH3-mediated novel interactions was detected in recent all genome high throughput protein interaction projects. Here we show that the SH3-mediated association of Abp1p with the Ser/Thr kinases Prk1p and Ark1p is essential for their localization to actin cortical patches. The Abp1-SH3 domain has a rather unusual binding specificity, because its target peptides contain the tetrapentapeptide +XXXPXXPX+PXXL with positive charges flanking the polyproline core on both sides. Here we present the structure of the Abp1-SH3 domain solved at 1.3-A resolution. The peptide-binding pockets in the SH3 domain are flanked by two acidic residues that are uncommon at those positions in the SH3 domain family. We have shown by site-directed mutagenesis that one of these negatively charged side chains may be the key determinant for the preference for non-classical ligands.     

Evaluation of different alpha-Galactosyl glycoconjugates for use in xenotransplantation

Porcine organs are rapidly rejected after transplantation into primate recipients due to the presence of preexisting immunoglobulins that bind to terminal galactose alpha1,3 galactose residues (alpha-galactosyl) present on porcine glycoproteins and glycolipids. Currently available immunosuppressive reagents have been largely ineffective at controlling the synthesis of these anti-Gal antibodies. Nonantigenic hapten polymers have been shown to be effective materials for blocking humoral immune responses in various model systems. We have developed a series of alpha-galactosyl glycoconjugate polymers and tested their ability to block anti-Gal antibody binding in vitro and in vivo. A galactose alpha1,3 galactose beta 1,4 GlcNAc trisaccharide free acid (TRFA) with a hexanoic acid spacer, containing five methylene groups and a carboxylic acid, was produced and coupled to a variety of polymeric backbones including dextran, branched poly(ethylene glycol) (PEG), and poly-L-lysine. The ability of monomeric TRFA and the alpha-galactosyl conjugates to block anti-Gal IgG and IgM binding was determined using a competition ELISA assay on defined HSA-Gal glycoconjugates and porcine microvascular endothelial cell substrates. We show that branched PEG carriers, with a TRFA sugar attached to each branch, exhibit enhanced antibody blocking ability compared to TRFA, but at higher target antigen densities these simple PEG conjugates are no more effective then an equivalent amount of TRFA in blocking anti-Gal IgM antibody interactions. In contrast, polymers of the branched PEG conjugates and linear conjugates made using dextran and poly-L-lysine were 2000 to 70000-fold more effective inhibitors of anti-Gal antibodies. In a study using nonhuman primates, a single dose infusion of polymeric PEG or dextran glycoconjugates dramatically reduced the level of circulating anti-Gal antibodies in cynomologus monkeys for at least 72 h. Glycoconjugates similar to these might be useful both to block anti-Gal interactions in vivo and to specifically control the induced anti-Gal immune response.     

A phylogenetic analysis of cordyliformes (Reptilia: Squamata): comparison of molecular and karyological data

A karyological study and the analysis of two mitochondrial genes were conducted in several species of cordyliformes from Madagascar. Both studies confirmed the monophyly of cordyliformes. The karyological conservatism and small genetic distance among mitochondrial genes observed in these species are in line with the hypothesis that all cordyliformes should be included in a single family. The two studies yielded contrasting results with regard to the relationships between the Malagasy species and the Cordylidae and Gerrhosauridae. Nonetheless, the consistency between the data from mitochondrial gene analysis and those of taxonomic studies based on morphological characters is more in favor of an affinity between Malagasy Zonosaurinae and Gerrhosauridae and suggests that the karyological similarities between the former and the Cordylidae may be due to plesiomorphy. Interesting, though not conclusive, data were also obtained on interspecific relationships among Zono-     

A novel class of microbial phosphocholine-specific phospholipases C

In this report we describe the 1,500-fold purification and characterization of the haemolytic phospholipase C (PLC) of Pseudomonas aeruginosa, the paradigm member of a novel PLC/phosphatase superfamily. Members include proteins from Mycobacterium tuberculosis, Bordetella spp., Francisella tularensis and Burkholderia pseudomallei. Purification involved overexpression of the plcHR1,2 operon, ion exchange chromatography and native preparative polyacrylamide gel electrophoresis. Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry confirmed the presence of two proteins in the purified sample with sizes of 17,117.2 Da (PlcR2) and 78,417 Da (PlcH). Additionally, liquid chromatography electrospray mass spectrometry (LCMS) revealed that PlcH and PlcR2 are at a stoichiometry of 1 : 1. Western blot analysis demonstrated that the enzyme purifies as a heterodimeric complex, PlcHR2. PlcHR2 is only active on choline-containing phospholipids. It is equally active on phosphatidylcholine (PC) and sphingomyelin (SM) and is able to hydrolyse plasmenylcholine phospholipids (plasmalogens). Neither PlcHR2 nor the M. tuberculosis homologues are inhibited by D609 a widely used, competitive inhibitor of the Bacillus cereus PLC. PlcH, PlcR2, and the PlcHR2 complex bind calcium. While calcium has no detectable effect on enzymatic activity, it inhibits the haemolytic activity of PlcHR2. In addition to being required for the secretion of PlcH, the chaperone PlcR2 affects both the enzymatic and haemolytic properties of PlcH. Inclusive in these data is the conclusion that the members of this PC-PLC and phosphatase family possess a novel mechanism for the recognition and hydrolysis of their respective substrates.     

Atrial natriuretic factor as marker of myocardial compromise in Chagas' disease

This study investigated the evolution of plasma atrial natriuretic factor (ANF) in patients in different stages of Chagas' disease and analyzed its usefulness as prognostic factor of the development of myocardial compromise in asymptomatic chagasic patients. Chagas' disease, a determinant of heart failure, is caused by the parasite Trypanosoma cruzi. A total of 21 chagasic patients were studied: 9 in the asymptomatic stage, 6 with conduction defects (CD), and 6 with chronic heart failure (CHF); and 31 controls: 16 healthy, 6 with CD, and 9 with CHF. Plasma ANF radioimmunoassay (RIA) and complementary studies were performed twice for each patient, with an interval period of 12 months. First sample: chagasic patients showed higher ANF levels in the CHF group than in CD and asymptomatic subjects; second sample: the peptide levels were higher in CHF patients than in the asymptomatic group. In non-chagasic CHF patients, ANF levels were higher than in CD patients and controls in both samples. ANF levels were not able to differentiate chagasic asymptomatic and CD patients from healthy subjects and CD controls; meanwhile, chagasic CHF patients showed lower plasma ANF than their controls. Furthermore, ANF is a sensitive marker capable of detecting gradual impairments in cardiac function in all patients studied.     

Courtship and other behaviors affected by a heat-sensitive,molecularly novel mutation in the cacophony calcium-channel gene of Drosophila

The cacophony (cac) locus of Drosophila melanogaster, which encodes a calcium-channel subunit, has been mutated to cause courtship-song defects or abnormal responses to visual stimuli. However, the most recently isolated cac mutant was identified as an enhancer of a comatose mutation's effects on general locomotion. We analyzed the cac(TS2) mutation in terms of its intragenic molecular change and its effects on behaviors more complex than the fly's elementary ability to move. The molecular etiology of this mutation is a nucleotide substitution that causes a proline-to-serine change in a region of the polypeptide near its EF hand. Given that this motif is involved in channel inactivation, it was intriguing that cac(TS2) males generate song pulses containing larger-than-normal numbers of cycles--provided that such males are exposed to an elevated temperature. Similar treatments caused only mild visual-response abnormalities and generic locomotor sluggishness. These results are discussed in the context of calcium-channel functions that subserve certain behaviors and of defects exhibited by the original cacophony mutant. Despite its different kind of amino-acid substitution, compared with that of cac(TS2), cac(S) males sing abnormally in a manner that mimics the new mutant's heat-sensitive song anomaly.     

Prevalence of hepatitis C Virus infection among hemophiliacs in Central Brazil

In order to investigate the hepatitis C virus (HCV) infection prevalence and risk factors in hemophiliacs in Central Brazil, 90 patients were interviewed and serum samples tested for HCV RNA and anti-HCV antibodies. An overall prevalence of 63.3% (CI 95%: 53.0-72.7) was found. Multivariate analysis of risk factors showed that number of blood transfusions was significantly associated with this infection. Most hemophiliacs received locally produced cryoprecipitate. All infected patients were transfused before the screening of blood units for anti-HCV. However, hemophiliacs who received exclusively screened cryoprecipitate were HCV negative. It confirms the expected decline in transfusion-acquired hepatitis C.