Urine metabolites are associated with glomerular lesions in type 2 diabetes

Introduction

Little is known about the association of urine metabolites with structural lesions in persons with diabetes.

Objectives

We examined the relationship between 12 urine metabolites and kidney structure in American Indians with type 2 diabetes.

Methods

Data were from a 6-year clinical trial that assessed renoprotective efficacy of losartan, and included a kidney biopsy at the end of the treatment period. Metabolites were measured in urine samples collected within a median of 6.5 months before the research biopsy. Associations of the creatinine-adjusted urine metabolites with kidney structural variables were examined by Pearson’s correlations and multivariable linear regression after adjustment for age, sex, diabetes duration, hemoglobin A_1c, mean arterial pressure, glomerular filtration rate (iothalamate), and losartan treatment.

Results

Participants (n?=?62, mean age 45?±?10 years) had mean?±?standard deviation glomerular filtration rate of 137?±?50 ml/min and median (interquartile range) urine albumin:creatinine ratio of 34 (14–85) mg/g near the time of the biopsy. Urine aconitic and glycolic acids correlated positively with glomerular filtration surface density (partial r?=?0.29, P?=?0.030 and r?=?0.50, P?<?0.001) and total filtration surface per glomerulus (partial r?=?0.32, P?=?0.019 and r?=?0.43, P?=?0.001). 2-ethyl 3-OH propionate correlated positively with the percentage of fenestrated endothelium (partial r?=?0.32, P?=?0.019). Citric acid correlated negatively with mesangial fractional volume (partial r=-0.36, P?=?0.007), and homovanillic acid correlated negatively with podocyte foot process width (partial r=-0.31, P?=?0.022).

Conclusions

Alterations of urine metabolites may associate with early glomerular lesions in diabetic kidney disease.

     

Adjustments of Protein Metabolism in Fasting Arctic Charr,Salvelinus alpinus

Protein metabolism, including the interrelated processes of synthesis and degradation, mediates the growth of an animal. In ectothermic animals, protein metabolism is responsive to changes in both biotic and abiotic conditions. This study aimed to characterise responses of protein metabolism to food deprivation that occur in the coldwater salmonid, Arctic charr, Salvelinus alpinus. We compared two groups of Arctic charr: one fed continuously and the other deprived of food for 36 days. We measured the fractional rate of protein synthesis (K_S) in individuals from the fed and fasted groups using a flooding dose technique modified for the use of deuterium-labelled phenylalanine. The enzyme activities of the three major protein degradation pathways (ubiquitin proteasome, lysosomal cathepsins and the calpain systems) were measured in the same fish. This study is the first to measure both K_S and the enzymatic activity of protein degradation in the same fish, allowing us to examine the apparent contribution of different protein degradation pathways to protein turnover in various tissues (red and white muscle, liver, heart and gills). K_S was lower in the white muscle and in liver of the fasted fish compared to the fed fish. There were no observable effects of food deprivation on the protease activities in any of the tissues with the exception of liver, where the ubiquitin proteasome pathway seemed to be activated during fasting conditions. Lysosomal proteolysis appears to be the primary degradation pathway for muscle protein, while the ubiquitin proteasome pathway seems to predominate in the liver. We speculate that Arctic charr regulate protein metabolism during food deprivation to conserve proteins.     

Identification and characterization of a novel high-molecular-weight form of the integrin alpha 3 subunit.

The integrin alpha 3 beta 1 is a multiligand extracellular matrix receptor found on many cell types. Immunoprecipitations of 125I-surface-labeled prostate carcinoma cell lines, DU145 and PC-3, with the anti-alpha 3 integrin monoclonal antibodies J143 or PIB5, resulted in the coimmunoprecipitation, along with the expected alpha 3 beta 1 heterodimer, of a polypeptide with a molecular mass of 225 kDa. This protein could also be copurified with the 155-kDa alpha 3 and 115-kDa beta 1 subunits upon affinity chromatography of 125I-surface-labeled cell extracts on anti-alpha 3 antibody-Sepharose columns. Upon reduction, this 225-kDa protein generated 130- and 95-kDa polypeptides, while the 155-kDa alpha 3 subunit generated 130- and 25-kDa polypeptides. The 225-kDa protein did not generate a 25-kDa polypeptide. Deglycosylation and reduction of the 225-kDa protein resulted in the generation of 110- and 95-kDa polypeptides, while deglycosylation and reduction of the 155-kDa alpha 3 resulted in a 110-kDa polypeptide identical in size to the 110-kDa polypeptide generated from the 225-kDa protein. Peptide maps generated from the 110-kDa components of the 225-kDa polypeptide and the 155-kDa alpha 3 integrin subunit were identical, as were their N-terminal amino acid sequences. An antibody directed against the cytoplasmic domain of the alpha 3 subunit immunoprecipitated the 225-kDa polypeptide in addition to the 155-kDa alpha 3 subunit. Furthermore, Northern blot analysis of RNA from DU145 and PC-3 cells with a human alpha 3 cDNA probe identified an mRNA species of 6.2 kb in addition to a major mRNA species of 4.3 kb. The larger mRNA species, which is of an appropriate size for encoding a polypeptide of approximately 220-kDa, was not detectable in cells which did not express the 225-kDa protein. These data demonstrate that the 225-kDa polypeptide represents a novel integrin alpha 3 subunit consisting of the alpha 3 integrin heavy chain disulfide-bonded to a 95-kDa polypeptide which may represent an alternative "light" chain to the 25-kDa light chain of the alpha 3 subunit.     

Pearl Formation: Persistence of the Graft During the Entire Process of Biomineralization

Most bivalves species of the genus Pinctada are well known throughout the world for production of white or black pearls of high commercial value. For cultured pearl production, a mantle allograft from a donor is implanted into the gonad of a recipient oyster, together with a small inorganic bead. Because of the dedifferentiation of cells during the first steps of the host oyster's immunological reaction, so far the fate of the graft and its exact role in the process of pearl formation could not be determined via classical histological methods. Here we report the first molecular evidence of the resilience of the graft in the recipient organism by showing that cells containing genome from the donor are still present at the end of pearl formation. These results suggest the existence of a unique biological cooperation leading to the successful biomineralization process of nacreous secretion in pearl formation.     

Substituent-specific antibody against glucuronoxylan reveals close association of glucuronic acid and acetyl substituents and distinct labeling patterns in tree species

Immunolabeling can be used to locate plant cell wall carbohydrates or other components to specific cell types or to specific regions of the wall. Some antibodies against xylans exist; however, many partly react with the xylan backbone and thus provide limited information on the type of substituents present in various xylans. We have produced a monoclonal antibody which specifically recognizes glucopyranosyl uronic acid (GlcA), or its 4-O-methyl ether (meGlcA), substituents in xylan and has no cross-reactivity with linear or arabinofuranosyl-substituted xylans. The UX1 antibody binds most strongly to (me)GlcA substitutions at the non-reducing ends of xylan chains, but has a low cross-reactivity with internal substitutions as well, at least on oligosaccharides. The antibody labeled plant cell walls from both mono- and dicotyledons, but in most tissues an alkaline pretreatment was needed for antibody binding. The treatment removed acetyl groups from xylan, indicating that the vicinity of glucuronic acid substituents is also acetylated. The novel labeling patterns observed in the xylem of tree species suggested that differences within the cell wall exist both in acetylation degree and in glucuronic acid content.     

Structural heterogeneity of wheat arabinoxylans revealed by Raman spectroscopy

A set of arabinoxylan samples differing in their arabinose composition and various samples of arabino-xylo-oligosaccharide samples were analysed by Raman spectroscopy. Specific signatures for arabinose substitution were found in several spectral regions, that is, 400-600, 800-950 and 1030-1100 cm(-1). A linear relationship was observed between the peak ratio 855/895 cm(-1) of the second derivative spectra and the A/X ratio determined by chemical analysis. Moreover, spectral changes were observed in the 400-600 cm(-1) region assigned to the coupled vibrations mode in the skeleton: while the intensity of the band at 570 cm(-1) increased with the degree of substitution, that at 494 cm(-1) decreased. Similarly, a linear relationship was observed between the peak intensity ratio 570/494 cm(-1) calculated on the second derivative spectra and the composition data. Analysis of Raman spectra of arabino-xylo-oligosaccharides allowed to identify specific spectral features of disubstitution.     

Molecular epidemiology of Vibrio nigripulchritudo, a pathogen of cultured penaeid shrimp (Litopenaeus stylirostris) in New Caledonia

A collection of 57 isolates of Vibrio nigripulchritudo from either diseased or healthy shrimp and from shrimp farms environment was studied in order to gain a better understanding of the epidemiology of this pathogen, notably isolated from two distinct shrimp disease complexes. Molecular typing using two different techniques, arbitrarily primed PCR (AP-PCR) and multi-locus sequence typing (MLST), studied together with experimental pathology data allowed a relevant epidemiological insight into this possibly emerging pathogen. Additionally, results obtained with the two molecular typing techniques were congruent and allowed discriminating the strains associated with the "Summer Syndrome" from strains isolated from other contexts, especially the other shrimp vibriosis "Syndrome 93". These results highlight that the "Summer Syndrome" is most probably caused by an emergent clonal pathogen that therefore deserves surveillance and that AP-PCR can satisfactorily be used for that purpose.     

Integrating genes and phenotype: a wheat–Arabidopsis–rice glycosyltransferase database for candidate gene analyses

Glycosyltransferases (GTs) constitute a very large multi-gene superfamily, containing several thousand members identified in sequenced organisms especially in plants. GTs are key enzymes involved in various biological processes such as cell wall formation, storage polysaccharides biosynthesis, and glycosylation of various metabolites. GTs have been identified in rice (Oryza sativa) and Arabidopsis thaliana, but their precise function has been demonstrated biochemically for only a few. In this work we have established a repertoire of virtually all the wheat (Triticum aestivum) GT sequences, using the large publicly available banks of expressed sequences. Based on sequence similarity with Arabidopsis and rice GTs compiled in the carbohydrate active enzyme database (CAZY), we have identified and classified these wheat sequences. The results were used to feed a searchable database available on the web () that can be used for initiating an exhaustive candidate gene survey in wheat applied to a particular biological process. This is illustrated through the identification of GT families which are expressed during cell wall formation in wheat grain maturation. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. This work was funded by a grant of the French ministry of research.