Organic carbon composition of marine sediments: effect of oxygen exposure on oil generation potential.

Anaerobic sedimentary conditions have traditionally been linked to the generation of the source rocks for petroleum formation. However, the influence of sedimentary redox conditions on the composition of freshly deposited organic matter (OM) is not clear. We assessed the effect of in situ exposure time to oxic conditions on the composition of OM accumulating in different coastal and deep-sea sediments using solid-state 13C nuclear magnetic resonance (NMR). 13C NMR spectra were resolved into mixtures of model components to distinguish between alkyl carbon present in protein and nonprotein structures. There is an inverse relation between the length of exposure to oxic conditions and the relative abundance of nonprotein alkyl (alkylNP) carbon, whose concentration is two orders of magnitude higher in coastal sediments with short exposure times than in deep-sea sediments with long exposure times. All alkylNP-rich samples contain a physically separate polymethylene component similar in composition to algaenans and kerogens in type I oil shales. The duration of exposure to oxic conditions appears to directly influence the quality and oil generation potential of OM in marine shales.

Physiologic, metabolic, and muscle fiber type characteristics of musculus uvulae in sleep apnea hypopnea syndrome and in snorers.

Upper airway dilator muscles play an important role in the pathophysiology of sleep apnea hypopnea syndrome (SAHS). The mechanical and structural characteristics of these muscles remain unknown. The aim of this study was to compare the physiologic, metabolic, and fiber type characteristics of one upper airway dilator muscle (musculus uvulae, MU) in 11 SAHS and in seven nonapneic snorers. The different analyses were done on MU obtained during uvulo-palato-pharyngoplasty. Snorers and SAHS differed only in their apnea + hypopnea indices (11.5 +/- 5.9 and 34.2 +/- 14.6/h, respectively, mean +/- SD). Absolute twitch and tetanic tension production of MU was significantly greater in SAHS than in snorers while the fatigability index was similar in the two groups. Protein content and anaerobic enzyme activities of MU were significantly greater in SAHS than in snorers; no difference was observed for aerobic enzyme activities. The total muscle fiber cross-sectional area of MU was significantly higher in SAHS (2.2 +/- 0.9 mm2) than in snorers (1.1 +/- 0.7 mm2). The surface occupied by type IIA muscle fibers of MU was larger in SAHS (2.00 +/- 0.96) than in snorers (0.84 +/- 0.63 mm2). We conclude that the capacity for tension production and the anaerobic metabolic activity of MU are greater in SAHS than in snorers.

Peroxisome proliferator-activated receptor γ activation favours selective subcutaneous lipid deposition by coordinately regulating lipoprotein lipase modulators, fatty acid transporters and lipogenic enzymes.

AIM: Peroxisome proliferator-activated receptor (PPAR) γ activation is associated with preferential lipoprotein lipase (LPL)-mediated fatty acid storage in peripheral subcutaneous fat depots. How PPARγ agonism acts upon the multi-level modulation of depot-specific lipid storage remains incompletely understood. METHODS: We evaluated herein triglyceride-derived lipid incorporation into adipose tissue depots, LPL mass and activity, mRNA levels and content of proteins involved in the modulation of LPL activity and fatty acid transport, and the expression/activity of enzymes defining adipose tissue lipogenic potential in rats treated with the PPARγ ligand rosiglitazone (30 mg kg(-1)  day(-1) , 23 days) after either a 10-h fasting period or a 17-h fast followed by 6 h of ad libitum refeeding. RESULTS: Rosiglitazone stimulated lipid accretion in subcutaneous fat (SF) ~twofold and significantly reduced that of visceral fat (VF) to nearly half. PPARγ activation selectively increased LPL mass, activity and the expression of its chaperone LMF1 in SF. In VF, rosiglitazone had no effect on LPL activity and downregulated the mRNA levels of the transendothelial transporter GPIHBP1. Overexpression of lipid uptake and fatty acid transport proteins (FAT/CD36, FATP1 and FABP4) and stimulation of lipogenic enzyme activities (GPAT, AGPAT and DGAT) upon rosiglitazone treatment were of higher magnitude in SF. CONCLUSIONS: Together these findings demonstrate that the depot-specific transcriptional control of LPL induced by PPARγ activation extends to its key interacting proteins and post-translational modulators to favour subcutaneous lipid storage.

Electrical stimulation-induced changes in skeletal muscle enzymes of men and women.

The purpose of the present study was to determine the effects of low-frequency electrical stimulation (LFES) on the skeletal muscle metabolic profile of men and women. The knee extensor muscles of sedentary men (N = 16) and women (N = 10) were submitted to 3 h.d-1 of 8-Hz neuromuscular electrical stimulation with the use of a portable stimulator (Respond II, Medtronic), 6 d.wk-1 for 6 wk. Enzyme activity levels of creatine kinase (CK), hexokinase (HK), glyceraldehydephosphate dehydrogenase (GAPDH), 3-hydroxyacyl CoA dehydrogenase (HADH), citrate synthase (CS), phosphofructokinase (PFK), and cytochrome c oxidase (COX) were determined in vastus lateralis muscle samples taken before and after the LFES protocol. The analyses of variance revealed no change in CK and in GAPDH. However, a small decrease in PFK activity, the rate-limiting enzyme of glycolysis, was observed in female (8%) and in male subjects (10%), but it reached significance in males only (P < 0.05). The activity level of HK, a regulatory enzyme of the skeletal muscle glucose phosphorylation (HK), increased significantly in female subjects only (36%; P < 0.01) in response to the stimulation protocol. Activity level of marker enzymes of the Krebs cycle (CS) and of the electron-transfert chain (COX) significantly increased in males (18% and 16%; P < 0.05) as well as in females (31% and 19%; P < 0.05). Increment in the marker enzyme activity of the fatty acid oxidation (HADH) was significant in female subjects (30%; P < 0.01) and, although significant, rather modest in male subjects (12%; P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Multielemental analysis of human fetal tissues using inductively coupled plasma-mass spectrometry.

Inductively coupled plasma-mass spectrometry (ICP-MS) was used to study the distribution of 26 major and trace elements in six tissues from 21 human fetuses aged 16-22 wk. Brain, lung, spleen, kidney, heart, and liver were analyzed following a microwave oven digestion step carried out according to clean techniques designed for ultratrace metal analyses. Precision and accuracy controls were conducted using standard reference material #1577b Bovine Liver. Significant differences among tissues were found for most of the elements. Essential trace elements seem to be increasingly retained as fetal tissues mature and become physiologically functional. The ranges of concentrations measured in fetal tissues at this stage of development are generally lower and much narrower than in adult tissues. The age of the fetus, which is not given in most studies, as well as the different techniques and levels of quality assurance could be responsible for the discrepancies in the trace metal concentrations reported here and in the literature. Intratissue homogeneity was also assessed in five human fetal brains. Frontal, occipital, parietal and temporal lobes, striatum, hippocampus, and thalamus were isolated and analyzed separately. No significant differences were found in the distribution of any of the elements at this stage of development. Because of the relatively narrow ranges of concentrations found for most elements, we believe that the results presented in this study represent the inorganic fingerprint of the main tissues of normal fetuses at midpregnancy for the Greater Montreal area.

PPARgamma agonism increases rat adipose tissue lipolysis, expression of glyceride lipases, and the response of lipolysis to hormonal control.

AIMS/HYPOTHESIS: The aim of this study was to investigate the effect and mechanisms of action of in vivo peroxisome proliferator-activated receptor gamma (PPARgamma) activation on white adipose tissue (WAT) lipolysis and NEFA metabolism. MATERIALS AND METHODS: Study rats were treated for 7 days with 15 mg/kg of rosiglitazone per day; control rats were not treated. After a 6-h fast, lipolysis and levels of mRNA for lipases were assessed in explants from various adipose depots. RESULTS: Rosiglitazone markedly increased basal and noradrenaline (norepinephrine)-stimulated glycerol and NEFA release from WAT explants, and amplified their inhibition by insulin. Primary adipocytes isolated from PPARgamma agonist-treated rats were also more responsive to noradrenaline stimulation expressed per cell, ruling out a contribution of an altered number of mature adipocytes in explants. Rosiglitazone concomitantly increased levels of mRNA transcripts for adipose triglyceride lipase (ATGL) and monoglyceride lipase (MGL) in subcutaneous and visceral WAT, and mRNA for hormone-sensitive lipase (HSL) in subcutaneous WAT. Lipase expression increased within 12 h of in vitro exposure of naïve explants to rosiglitazone, suggesting direct transcriptional activation. In parallel, chronic in vivo treatment with rosiglitazone lowered plasma NEFAs and in WAT its expected stimulatory action on glycerol and NEFA recycling, and on the expression of genes involved in NEFA uptake and retention by WAT, such processes counteracting net NEFA export. CONCLUSIONS/INTERPRETATION: These findings demonstrate that, in the face of its plasma NEFA-lowering action, PPARgamma agonism stimulates WAT lipolysis, an effect that is compensated by lipid-retaining pathways. The results further suggest that PPARgamma agonism stimulates lipolysis by increasing the lipolytic potential, including the expression levels of the genes encoding adipose triglyceride lipase and monoglyceride lipase.

Comparisons between the inorganic content of healthy and hypertensive rat tissues by inductively coupled plasma-mass spectrometry.

The inorganic contents of bone, brain, erythrocyte, heart, kidney cortex, kidney medulla, liver, lung, muscle and plasma from spontaneously hypertensive rats were compared with those of the same tissues from healthy Sprague-Dawley rats. A general inductively coupled plasma-mass spectrometry method developed for multi-element determinations of most of the elements present in biological tissues was used. Variations were found not only for major elements, as expected, but also for many trace elements in several tissues.

Determination of total iodine in nutritional and biological samples by ICP-MS following their combustion within an oxygen stream.

A mineralization and determination method for total iodine in nutritional and biological samples is described. Combustion of the sample in an oxygen stream is followed by collection of the combustion products in a 5% water-soluble tertiary amine solution. Iodine is determined by inductively coupled plasma mass spectrometry. The accuracy and precision of the quantitative iodine analysis using standard addition is better than +/- 10%. A semi-quantitative analysis of four standard reference materials is evaluated. Owing to the presence of low-level iodine contaminant in the blank solution, the determination limit of the method is +/- 10 micrograms kg-1. Good agreement with certified iodine values is obtained for six reference materials. The use of the tertiary amine matrix solution permits the simultaneous determination of iodine and other trace metals of biological and toxicological importance, including Mn, Co, Ni, Cu, Zn, Rb, Cd, and Pb.

Complete analysis of the trace elements of the kidney.

The distribution of trace elements in kidney cortex and medulla and in their subcellular fractions was studied by inductively coupled plasma mass spectrometry (ICP-MS). This technology allows the analysis of almost all the elements of the periodic table, along with their isotopes, in the same experiment. Acid digestion of the tissue (samples) was required before ICP-MS elemental analysis. Mineralization in 8 N nitric acid for 2 min in a Parr microwave acid digestion bomb, inside a regular microwave oven working at medium power, gave good sensitivity and reproducible results. Trace element determinations could be precisely performed, despite the presence of a considerable amount of organic matter. Cortex/plasma and medulla/plasma inorganic ratios were taken as indicators of the inorganic bioaccumulation. The highest enrichment factors of elements found in the cortex were Mn greater than Co greater than Tl greater than Zn greater than Rb greater than Mo greater than Cu and the highest element enrichments of the medulla were Tl greater than Mn greater than Co greater than Rb greater than Zn greater than Bi greater than Mo greater than Ni greater than Cu. Subcellular fragmentation of the kidney cortex and medulla indicated that the majority of the trace elements was located in the cytosolic fraction. The membrane fraction of the medulla contained significant amounts of Hg and Al: 120.7 and 32.0 mg/g protein, respectively. Cu and Zn were the most abundant trace elements found in the brush border membrane from the cortex: 120.7 and 68.2 mg/g protein, respectively. These quantities are largely in excess of what is bound, for example, to alkaline phosphatase.(ABSTRACT TRUNCATED AT 250 WORDS)

Mitochondrial DNA polymorphism detected with the restriction enzymes BstNI and BclI in a French Canadian population.

The enzymes BstNI and BclI were used to detect various human mitochondrial DNA RFLPs in a sample of 104 unrelated French Canadians. These sequence variations were found in total white blood cell DNA probed with whole human mitochondrial DNA. With BstNI, 6 mitochondrial DNA restriction patterns (morphs) were identified. BstNI morphs 2-6 each differ from morph 1 by one single distinct restriction site gain or loss on the mitochondrial DNA molecule. Although BstNI morph 1 was found in most of the subjects (80%), each other morph was observed at a frequency of at least 3%. With the enzyme BclI, 4 different morphs were detected. Morphs 2-4 also result from different single restriction site alteration as compared with BclI morph 1. The morph 1 was clearly the most frequent (95%) while morphs 3 and 4 were present in only 1% of the subjects. These data indicate that the enzyme BstNI and, to a much lesser extent, the enzyme BclI detect mitochondrial DNA polymorphism in Caucasians. They are therefore of interest for population genetics studies.

An improved thermal oxidation method for the quantification of soot/graphitic black carbon in sediments and soils.

Recent findings have confirmed the importance of black carbon (BC) in the global biogeochemical cycles of carbon and oxygen through its important contribution to the slowly cycling organic carbon (OC) pool. Yet, most BC determination methods published to date measure operationally defined BC fractions, oftentimes with a high potential for artifacts and a lack of specificity for one of the two major forms of the BC continuum, soot/graphitic BC (GBC) and char/charcoal BC (CBC). This paper describes a method that reduces the potential for artifacts to accurately and selectively measure the concentration of GBC in complex mineral and organic matrixes. Marine and lacustrine sediments, river sediments, suspended particles, and a marine plankton sample were first demineralized with a mixture of hydrochloric (HCl) and hydrofluoric (HF) acids to expose any biochemical entrapped in a mineral matrix. The hydrolyzable organic matter fraction (mostly proteins and carbohydrates) was then removed with 02-free trifluoroacetic acid and HCl, after which the non-GBC, non-hydrolyzable OC fraction was finally removed by thermal oxidation at 375 degrees C for 24 h. The specificity of the method for GBC was assessed with pure CBC and GBC samples. Detection limit and GBC recovery in spiked samples were 10 mg kg(-1) and approximately 85%, respectively. Typical GBC concentrations measured in a series of natural samples ranged from <10 mg kg(-1) in marine plankton to 0.19% in a riverine sample. These concentrations were lower by as much as 3 orders of magnitude than those obtained by thermal oxidation without demineralization and removal of hydrolyzable organic matter. The improvements presented in this work allow for the accurate and precise measurement of GBC in complex organic and mineral matrixes by eliminating the interference caused by the presence of CBC, residual non-BC OC and minerals, or by the formation of condensation products that could account for as much as 4-6% of total OC. Combined to stable and radioisotope analysis, this improved method should permit quantitative assessments of the role and dynamics of GBC in the global geochemical cycles of carbon and oxygen.

Evidence for non-selective preservation of organic matter in sinking marine particles.

The sinking of particulate organic matter from ocean surface waters transports carbon to the ocean interior, where almost all is then recycled. The unrecycled fraction of this organic matter can become buried in ocean sediments, thus sequestering carbon and so influencing atmospheric carbon dioxide concentrations. The processes controlling the extensive biodegradation of sinking particles remain unclear, partly because of the difficulty in resolving the composition of the residual organic matter at depth with existing chromatographic techniques. Here, using solid-state 13C NMR spectroscopy, we characterize the chemical structure of organic carbon in both surface plankton and sinking particulate matter from the Pacific Ocean and the Arabian Sea. We found that minimal changes occur in bulk organic composition, despite extensive (>98%) biodegradation, and that amino-acid-like material predominates throughout the water column in both regions. The compositional similarity between phytoplankton biomass and the small remnant of organic matter reaching the ocean interior indicates that the formation of unusual biochemicals, either by chemical recombination or microbial biosynthesis, is not the main process controlling the preservation of particulate organic carbon within the water column at these two sites. We suggest instead that organic matter might be protected from degradation by the inorganic matrix of sinking particles.