50,823 research outputs found
Postnatal regulation of myosin heavy chain isoform expression and metabolic enzyme activity by nutrition
No full textDevelopment of muscle is critically dependent on several hormones which in turn are regulated by nutritional status. We therefore determined the impact of mild postnatal undernutrition on key markers of myofibre function: type I slow myosin heavy chain (MyHC) isoform, myosin ATPase, succinate dehydrogenase and α-glycerophosphate dehydrogenase. In situ hybridization, immunocytochemistry and enzyme histochemistry were used to assess functionally distinct muscles from 6-week-old pigs which had been fed an optimal (6 % (60 g food/kg body weight per d)) or low (2 % (20 g food/kg per d)) intake for 3 weeks, and kept at 26°C. Nutritional status had striking muscle-specific influences on contractile and metabolic properties of myofibres, and especially on myosin isoform expression. A low food intake upregulated slow MyHC mRNA and protein levels in rhomboideus by 53 % (P < 0·01) and 18 % (P < 0·05) respectively; effects in longissimus dorsi, soleus and diaphragm were not significant. The oxidative capacity of all muscles increased on the low intake, albeit to varying extents: longissimus dorsi (55 %), rhomboideus (30 %), soleus (21 %), diaphragm (7 %). Proportions of slow oxidative fibres increased at the expense of fast glycolytic fibres. These novel findings suggest a critical role for postnatal nutrition in regulating myosin gene expression and muscle phenotype. They have important implications for optimal development of human infants: on a low intake, energetic efficiency will increase and the integrated response to many metabolic and growth hormones will alter, since both are dependent on myofibre type. Mechanisms underlying these changes probably involve complex interactions between hormones acting as nutritional signals and differential effects on their cell membrane receptors or nuclear receptors
Growth hormone receptor gene expression in porcine skeletal and cardiac muscles is selectively regulated by postnatal undernutrition
No full textDuring mild postnatal undernutrition, growth hormone receptor (GHR) mRNA abundance decreases in liver but increases in longissimus dorsi muscle. We tested the following hypotheses: 1) GHR gene expression is related to the metabolic and contractile characteristics of different muscles, and 2) the GHR response to nutrition depends on muscle type. Eight pairs of littermate pigs were weaned at 3 wk and given an optimal [60 g/(kg·d)] or low [(20 g/(kg·d)] food intake for the next 3 wk. All pigs grew, but at a slower rate in the low food intake group (P 0.10). Compared with the high intake pigs, hepatic GHR mRNA was downregulated in the low intake pigs by 59% (P 0.4); soleus, 65% (P < 0.05); cardiac, 51% (P < 0.05). Moreover, the proportion of skeletal muscle fibers with high oxidative capacity was also greater in the low intake group (P < 0.05). We conclude that postnatal GHR gene expression and its regulation by mild undernutrition are related to the metabolic, contractile and specific functional properties of different muscles
A 2 h periodic variation in the low-mass X-ray binary Ser X-1
No full textSpectroscopy of the low-mass X-ray binary Ser X-1 using the Gran Telescopio Canarias have revealed a ?2 h periodic variability that is present in the three strongest emission lines. We tentatively interpret this variability as due to orbital motion, making it the first indication of the orbital period of Ser X-1. Together with the fact that the emission lines are remarkably narrow, but still resolved, we show that a main-sequence K dwarf together with a canonical 1.4 M? neutron star gives a good description of the system. In this scenario, the most likely place for the emission lines to arise is the accretion disc, instead of a localized region in the binary (such as the irradiated surface or the stream-impact point), and their narrowness is due instead to the low inclination (?10°) of Ser X-1
Extracting Boer-Mulders functions from p+D Drell-Yan processes
No full textWe extract the Boer- Mulders functions of valence and sea quarks in the proton from unpolarized p + D Drell- Yan data measured by the FNAL E866 Collaboration. Using these Boer- Mulders functions, we calculate the cos2 phi asymmetries in unpolarized pp Drell- Yan processes, both for the FNAL E866/ NuSea and the BNL Relativistic Heavy Ion Collider experiments. We also estimate the cos2 phi asymmetries in the unpolarized p (P) over bar Drell- Yan processes at GSI.Astronomy & AstrophysicsPhysics, Particles & FieldsSCI(E)37ARTICLE5null7
Growth hormone receptor gene expression is related to metabolic and contractile properties of muscle
No full textApplicazione di biotecnologie nello studio delle interazioni fra stato nutrizionale ed accrescimento
No full textMeasurements of the decays B-0 -> (D)over-bar(0) p(p)over-bar, B0 -> (D)over-bar*(0) p(p)over-bar, B-0 -> D- p(p)over-bar pi(+), and B-0 -> D*(-) p(p)over-bar pi(+)
No full textWe present measurements of branching fractions of B-0 decays to multibody final states containing protons, based on 232x10(6) Upsilon(4S)-> B (B) over bar decays collected with the BABAR detector at the SLAC PEP-II asymmetric-energy B factory. We measure the branching fractions B(B-0 ->(D) over bar (0)p (p) over bar)=(1.13 +/- 0.06 +/- 0.08)x10(-4), B(B-0 ->(D) over bar (*0)p (p) over bar)=(1.01 +/- 0.10 +/- 0.09)x10(-4), B(B-0 -> D(-)p (p) over bar pi(+))=(3.38 +/- 0.14 +/- 0.29)x10(-4), and B(B-0 -> D(*-)p (p) over bar pi(+))=(4.81 +/- 0.22 +/- 0.44)x10(-4) where the first error is statistical and the second systematic. We present a search for the charmed pentaquark state, Theta(c)(3100) observed by H1 and put limits on the branching fraction B(B-0 ->Theta(c)(p) over bar pi(+))xB(Theta(c)-> D(*-)p)Theta(c)(p) over bar pi(+))xB(Theta(c)-> D(-)p)< 9x10(-6). Upon investigation of the decay structure of the above four B-0 decay modes, we see an enhancement at low p (p) over bar mass and deviations from phase-space in the (D) over bar(p) over bar and (D) over bar invariant mass spectra
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