The release of GLP-1 and ghrelin, but not GIP and CCK, by glucose is dependent upon the length of small intestine exposed

Previous observations suggest that glucagon-like peptide-1 (GLP-1) is released into the bloodstream only when dietary carbohydrate enters the duodenum at rates that exceed the absorptive capacity of the proximal small intestine to contact GLP-1 bearing mucosa in more distal bowel. The aims of this study were to determine the effects of modifying the length of small intestine exposed to glucose on plasma concentrations of GLP-1 and also glucose-dependent insulinotropic peptide (GIP), insulin, cholecystokinin (CCK) and ghrelin, and antropyloric pressures. Glucose was infused at 3.5 kcal/min into the duodenum of eight healthy males (age 18-59 yr) over 60 min on the first day into an isolated 60-cm segment of the proximal small intestine ("short-segment infusion"); on the second day, the same amount of glucose was infused with access to the entire small intestine ("long-segment infusion"). Plasma GLP-1 increased and ghrelin decreased (P < 0.05 for both) during the long-, but not the short-, segment infusion. By contrast, increases in plasma CCK and GIP did not differ between days. The rises in blood glucose and plasma insulin were greater during the long- than during the short-segment infusion (P < 0.05). During the long- but not the short-segment infusion, antral pressure waves (PWs) were suppressed (P < 0.05). Isolated pyloric PWs and basal pyloric pressure were stimulated on both days. In conclusion, the release of GLP-1 and ghrelin, but not CCK and GIP, is dependent upon >60 cm of the intestine being exposed to glucose.     

Reduced expression of regucalcin in young and aged mdx diaphragm indicates abnormal cytosolic calcium handling in dystrophin-deficient muscle

The cytosolic Ca2+ -binding protein regucalcin is involved in intracellular signaling and present in high abundance in the liver. Here, we could show by comparative mass spectrometry-based proteomics screening of normal versus dystrophic fibres that regucalcin of 33.9 kDa and pI5.2 also exists in diaphragm muscle. Since the expression of sarcolemmal Ca2+ -leak channels and luminal Ca2+ -binding elements is altered in dystrophin-deficient muscle, we initiated this study in order to determine whether additional soluble muscle proteins involved in Ca2+ -handling are affected in muscular dystrophy. Following separation by two-dimensional gel electrophoresis, the spot pattern of the normal versus the mdx diaphragm muscle proteome was evaluated by densitometry. The expression levels of 20 major protein spots were shown to change and their identity determined by mass spectrometry. A 2-fold reduction of regucalcin in mdx diaphragm, as well as in dystrophic limb muscle and heart, was confirmed by immunoblotting in both young and aged mdx mice. The results from our proteomics analysis of dystrophic diaphragm support the concept that abnormal Ca2+ -handling is involved in x-linked muscular dystrophy. The reduction in key Ca2+ -handling proteins may result in an insufficient maintenance of Ca2+ -homeostasis and an abnormal regulation of Ca2+ -dependent enzymes resulting in disturbed intracellular signaling mechanisms in dystrophinopathies.     

High-fat diet effects on gut motility,hormone, and appetite responses to duodenal lipid in healthy men

There is evidence that gastrointestinal function adapts in response to a high-fat (HF) diet. This study investigated the hypothesis that an HF diet modifies the acute effects of duodenal lipid on appetite, antropyloroduodenal pressures, plasma CCK and plasma glucagon-like peptide-1 (GLP-1) levels in humans. Twelve healthy men were studied twice in randomized, crossover fashion. The effects of a 90-min duodenal lipid infusion (6.3 kJ/min) on the above parameters were assessed immediately following 14-day periods on either an HF or a low-fat (LF) diet. After the HF diet, pyloric tonic and phasic pressures were attenuated, and the number of antropyloroduodenal pressure-wave sequences was increased when compared with the LF diet. Plasma CCK and GLP-1 levels did not differ between the two diets. Hunger was greater during the lipid infusion following the HF diet, but there was no difference in food intake. Therefore, exposure to an HF diet for 14 days attenuates the effects of duodenal lipid on antropyloroduodenal pressures and hunger without affecting food intake or plasma hormone levels.     

Differential skeletal preservation at Windover Pond: causes and consequences

In this paper, we evaluate the causes of differential skeletal preservation in the Windover Pond skeletal series (8BR246). We collected data on sex and age for approximately 110 individuals, and calculated a preservation score for each individual based on the presence of 80 skeletal landmarks. Our research questions evaluated the relationship between bone preservation and individual age and sex, and between the presence of preserved brain material and skeletal preservation, and the effects of burial location on bone preservation. The results indicate variability in average preservation for the sample (micro = 0.53, SD = 0.22) with an apparent lack of sex-specific (P = 0.79) or age-specific (P = 0.37) differences in preservation. The relationship between brain and skeletal preservation (P = 0.15) was not significant. The horizontal distribution of burials was not significantly correlated with skeletal preservation (north: r = -0.10, P = 0.93; east: r = 0.09, P = 0.45); however, vertical depth was a significant predictor of preservation (r = -0.31, P = 0.005), indicating that skeletal preservation decreased as burials were located closer to the ground surface. The observed variability in preservation scores may be related to the partial drying and resubmergence of the uppermost burials for the last few millennia. Comparison of Windover element-specific survival rates with previous analyses based on terrestrial samples (Galloway et al. [1997] Forensic taphonomy, Boca Raton: CRC Press; Waldron [1987] Death, decay and reconstruction, Manchester: Manchester University Press; Willey et al. [1997] Am J Phys Anthropol 104:513-528) affirms the relationship between element weight or density and bone survival. The unique taphonomic context of our study sample effected little change in bone deterioration processes.     

Oxygen requirements and mass transfer in hairy-root culture

Oxygen mass transfer in clumps of Atropa belladonna hairy roots was investigated as a function of root density and external flow conditions. Convection was the dominant mechanism for mass transfer into root clumps 3.5 to 5.0 cm in diameter; Peclet numbers inside the clumps ranged from 1.4 x 10(3) to 7.1 x 10(4) for external superficial flow velocities between 0.4 and 1.4 cm s(-1). Local dissolved-oxygen levels and rates of oxygen uptake were measured in aflow chamber and in bubble column and stirred bioreactors. When air was used as oxygen source, intraclump dissolved-oxygen tensions ranged from90% to 100% air saturation at high external flow velocity andlow root density, to less than 20% air saturation in dense root clumps. Specific oxygen-uptake rate declined with increasing root density. When external boundary layers around individual roots were eliminated byforcing liquid through the clumps at superficial velocities between 0.2 and1.0 cm s(-1), internal dissolved-oxygen tension was maintained at 95% to 100% air saturation and rate of oxygen uptake at 1.6 x 10(-6) g g(-1) s(-1) dry weight. Liquid culture of single A. belladonna hairy roots was used to investigate the effect of dissolved-oxygen tensionon root growth and morphology. Total root length and number of root tips increased exponentially at oxygen tensions between 70% and 100%air saturation. Specific growth rate increased with oxygen tension up to 100% air saturation; this result demonstrates that hairy roots aeratedwithout oxygen supplementation are likely to be oxygenlimited. No growth occurred at 50% air saturation. Growth of hairy roots proceeded with an average length per tip of about 1 cm; this value was essentially independent of dissolved-oxygen tension between 70% and 100% air saturation. (c) 1994 John Wiley & Sons, Inc.     

Molecular analysis of the F plasmid traVR region: traV encodes a lipoprotein.

The nucleotide sequences of the conjugative F plasmid transfer region genes, traV and traR, have been determined. The deduced amino acid sequence of TraV indicated that it may be a lipoprotein; this was confirmed by examining the effect of globomycin on traV-encoded polypeptides synthesized in minicells. An open reading frame that may represent a previously undetected transfer gene, now designated trbG, was identified immediately upstream of traV. The deduced product of traR was found to share amino acid similarity with proteins from the bacteriophages 186 and P2 and with the dosage-dependent dnaK suppressor DksA.     

Microbial Transformations of Selenium

Resting cell suspensions of a strain of Corynebacterium isolated from soil formed dimethyl selenide from selenate, selenite, elemental selenium, selenomethionine, selenocystine, and methaneseleninate. Extracts of the bacterium catalyzed the production of dimethyl selenide from selenite, elemental selenium, and methaneseleninate, and methylation of the inorganic Se compounds was enhanced by S-adenosylmethionine. Neither trimethylselenonium nor methaneselenonate was metabolized by the Corynebacterium. Resting cell suspensions of a methionine-utilizing pseudomonad converted selenomethionine to dimethyl diselenide. Six of 10 microorganisms able to grow on cystine used selenocystine as a sole source of carbon and formed elemental selenium, and one of the isolates, a pseudomonad, was found also to produce selenide. Soil enrichments converted trimethylselenonium to dimethyl selenide. Bacteria capable of utilizing trimethylselenonium, dimethyl selenide, and dimethyl diselenide as carbon sources were isolated from soil.