Influence of substrate concentration and moisture content on the specific methanogenic activity of dry mesophilic municipal solid waste digestate spiked with propionate

The objective of this study was to evaluate the influence of substrate concentration and moisture content on the specific methanogenic activity (SMA) of a fresh dry mesophilic digestate from a municipal solid waste digester plant. For this purpose, SMA tests were performed under mesophilic conditions into glass bottles of 500 mL volume used as batch reactors, during a period of 20-25 days. Propionate was used as substrate at concentrations ranging from 1 to 10 gCOD/kg. Four moisture contents were studied: 65%, 75%, 80% and 82%. Experimental results showed that propionate concentration and moisture content strongly influenced the SMA. The highest SMA was observed at a substrate concentration of 10 gCOD/kg (11.3 mgCOD gVS⁻¹ d⁻¹ for the second dose of propionate) and at a moisture content of 82% (7.8 mgCOD gVS⁻¹ d⁻¹ for the second dose of propionate, at a concentration of 5 gCOD/kg). SMA was found to decrease linearly when decreasing the moisture content.     

Comparison of 16S rRNA sequencing with biochemical testing for species-level identification of clinical isolates of Neisseria spp.

We aimed to compare accuracy of genus and species level identification of Neisseria spp. using biochemical testing and 16S rRNA sequence analysis. These methods were evaluated using 85 Neisseria spp. clinical isolates initially identified to the genus level by conventional biochemical tests and API NH system (Bio-Mérieux^®). In 34 % (29/85), more than one possibility was given by 16S rRNA sequence analysis. In 6 % (5/85), one of the possibilities offered by 16S rRNA gene sequencing, agreed with the result given by biochemical testing. In 4 % (3/85), the same species was given by both methods. 16S rRNA gene sequencing results did not correlate well with biochemical tests.     

A novel frameshift mutation in BLM gene associated with high sister chromatid exchanges (SCE) in heterozygous family members

The Bloom syndrome (BS) is an autosomic recessive disorder comprising a wide range of abnormalities, including stunted growth, immunodeficiency, sun sensitivity and increased frequency of various types of cancer. Bloom syndrome cells display a high level of genetic instability, including a 10-fold increase in the sister chromatid exchanges (SCE) level. Bloom syndrome arises through mutations in both alleles of the BLM gene, which was identified as a member of the RecQ helicase family. In this study, we screened a Tunisian family with three BS patients. Cytogenetic analysis showed several chromosomal aberrations, and an approximately 14-fold elevated SCE frequency in BS cells. A significant increase in SCE frequency was observed in some family members but not reaching the BS patients values, leading to suggest that this could be due to the heterozygous profile. Microsatellite genotyping using four fluorescent dye-labeled microsatellite markers revealed evidence of linkage to BLM locus and the healthy members, sharing higher SCE frequency, showed heterozygous haplotypes as expected. Additionally, the direct BLM gene sequencing identified a novel homozygous frameshift mutation c.3617–3619delAA (p.K1207fsX9) in BS patients and a heterozygous BLM mutation in the family members with higher SCE frequency. Our findings suggest that this latter mutation likely leads to a reduced BLM activity explaining the homologous recombination repair defect and, therefore, the increase in SCE. Based on the present data, the screening of this mutation could contribute to the rapid diagnosis of BS. The genetic confirmation of the mutation in BLM gene provides crucial information for genetic counseling and prenatal diagnosis.     

Biochemical characterization, cloning, and molecular modelling of chicken pancreatic lipase

Chicken pancreatic lipase (CPL) was purified from delipidated pancreas. Pure CPL was obtained after ammonium sulphate fractionation, then DEAE-cellulose, Sephacryl S-200 gel filtration, and FPLC Mono-Q Sepharose columns. The pure lipase is a glycosylated monomer having a molecular mass of about 50kDa. The 23 N-terminal amino acid residues of CPL were sequenced. The sequence is similar to those of avian and mammalian pancreatic lipases. CPL presents the interfacial activation phenomenon tested with tripropionin or vinyl ester. When CPL was inhibited by synthetic detergent (TX-100) or amphipathic protein (BSA), simultaneous addition of bile salts and colipase was required to restore the full CPL activity. In the absence of colipase and bile salts, CPL was unable to hydrolyse tributyrin emulsion. This enzyme can tolerate, more efficiently than HPL, the accumulation of long-chain free fatty acids at the interface when olive oil emulsion was used as substrate in the absence of bile salts and colipase. The CPL activity, under these conditions, was linear whereas that of HPL decreased rapidly. Anti-TPL polyclonal antibodies cross-reacted specifically with CPL. The gene encoding the mature CPL was cloned and sequenced. The deduced amino acid sequence of the mature lipase shows a high degree of homology with the mammalian pancreatic lipases. A 3D structure model of CPL was built using the HPL structure as template. We have concluded that a slight increase in the exposed hydrophobic residues on the surface of CPL, as compared to HPL, could be responsible for a higher tolerance to the presence of long-chain free fatty acids at the lipid/water interface.     

Cardiorespiratory fitness in youth: relationship to insulin sensitivity and beta-cell function

Objective: We examined whether the relationship between cardiorespiratory fitness (CRF) and insulin sensitivity (IS)/secretion is independent of adiposity in healthy African‐American (n = 65) and white (n = 57) youth. Research Methods and Procedures: IS and β‐cell function were evaluated by a 3‐hour hyperinsulinemic‐euglycemic and a 2‐hour hyperglycemic (12.5 mM) clamp, respectively. Total fat was measured by DXA and abdominal fat with computed tomography. CRF (peak volume of oxygen) was measured using a graded maximal treadmill test. Results: Independent of race, CRF was inversely (p < 0.05) related to total and abdominal fat, fasting insulin and first phase insulin secretion, and positively (p < 0.05) related to IS. When subjects were categorized into low (≤50th) and high (>50th) CRF groups, IS was significantly (p < 0.05) higher in the high compared with the low CRF group independently of race. Furthermore, first and second phase insulin secretion were lower (p < 0.05) in the high CRF group in comparison with the low CRF group in both races. However, in multiple regression analyses CRF was not (p > 0.05) an independent predictor of IS and acute insulin secretion after accounting for total adiposity. Discussion: Our findings demonstrate that low CRF is associated with decreased IS compensated by higher insulin secretion in both African‐American and white youth. However, this relationship disappears after adjusting for differences in adiposity, suggesting that the association between fitness and IS is mediated, at least in part, through fatness.     

Synthesis and evaluation of anilinohexafluoroisopropanols as activators/modulators of LXRalpha and beta

A series of branched and unbranched anilinohexafluoroisopropanols related to the known sulfonamide T0901317 were prepared and evaluated as activators/modulators of both LXRalpha and LXRbeta. A structure-activity relationship was established and compounds with high potency on both the receptors were identified. Many compounds showed a tendency toward selectivity for LXRbeta versus LXRalpha. Several analogues were evaluated for effects on plasma lipoprotein levels in mice. A few of these significantly raised HDL-cholesterol levels in plasma but showed markedly different effects on liver triglyceride content, suggesting that this series may yield candidates with improved efficacy/safety profiles compared to existing molecules.     

Flexible synthesis and biological evaluation of novel 5-deoxyadenophorine analogues

Adenophorine and its 5-deoxy analogue have been identified as natural iminosugars with efficient glycosidase inhibitory effects. The syntheses and biological evaluation of two new series of 5-deoxyadenophorine analogues in their racemic form are reported. The compounds 12e and 13d bearing a C11 and C7 alkyl chain, respectively, were found to be potent inhibitors of the beta-glucosidase from almond with Ki near to 60 microM. The compounds 13a,d which possess a 3,4-cis stereochemistry were efficient on glucosidases but also on the beta-galactosidase, what was not observed with the 3,4-trans series 12.     

Chromosomal Aberrations (CA), Sister Chromatid Exchanges (SCE), and High-Frequency Cells (HFC) Frequencies in Peripheral Blood Lymphocytes of Tunisian Gasoline Truck Loaders

Gasoline constitutes a mixture of chemicals that contain well-known genotoxicants. Thus, chronic occupational exposure to gasoline may be considered to possess genotoxic risk. In this study, the frequencies of total chromosomal aberrations (TCA), aberrant cells (Ab.c.), sister chromatid exchanges (SCE), high-frequency cells (HFC), and high-frequency cell individual (HFI) were investigated in peripheral blood lymphocytes from 17 gasoline-exposed workers (10 smokers and 7 non-smokers) and 22 unexposed reference subjects (12 smokers and 10 non-smokers). The exposed subjects were gasoline truck loaders at a gasoline company from Tunis City, north of Tunisia. The results indicate multiple CA, such as dicentrics (DIC), chromatid breaks (SB), and chromosome breaks (DB). A significant difference was observed in TCA and Ab.c. frequencies between exposed and unexposed groups (p < 0.01). A significant difference was found in frequencies of SCE (p < 0.01) and HFI (p < 0.05) between exposed and unexposed groups. SCE and TCA frequencies of smokers were found to be significantly higher than those of non-smokers in both groups. There was an interaction between gasoline exposure and smoking habit for TCA (p = 0.020), but not for SCE. Our findings indicate that gasoline truck loaders were under risk of significant cytogenetic damage that was enhanced by their smoking habit.     

Asymmetry and steric hindrance in tripodal ligands: Reaching the limit for octahedral geometry with the newly synthesized [(6-bromo 2-pyridylmethyl) (6-fluoro 2-pyridylmethyl) (2-pyridylmethyl)] amine tripod in FeCl2 complexes

We have synthesized the fully unsymmetrical [(6-bromo 2-pyridylmethyl) (6-fluoro 2-pyridylmethyl) (2-pyridylmethyl)] amine tripod FBrTPA. The synthesis involves preparation of the already known [(6-bromo 2-pyridylmethyl) (2-pyridylmethyl)] amine BrDPA, which is obtained either by classical condensation of α-substituted pyridine carboxaldehyde with aminomethyl pyridine, or by a pathway involving the protection/deprotection sequence of this primary amine. This second way is useful for syntheses of monosubstituted DPAs in the cases where α-substituted pyridine carboxaldehydes are unavailable. The crystal structure of the FeCl₂ complex shows that the ligand binds in a κ⁴-N fashion, with however relatively long ligand-to-metal distances. The spectroscopic and electrochemical studies support decoordination of the bromopyridyl substituent in solution, with κ³-N coordination mode of the tripod within a complex displaying a trigonal bipyramidal geometry at the metal centre. This complex reacts easily with dry oxygen to yield an unsymmetrical μ-oxo diferric complex, the structure of which is also reported.