bluuebunny/crossref_metadata_2025_split huggingface dataset:
Assessment of criteria for improvement in Theileria orientalis sergenti infection tolerance
Authors: FUKASAWA Michiru , KIKUCHI Tadashi , KONASHI Shigeru , NISHIDA Akira , YAMAGISHI Toshihiro 
Published: March 2003

ABSTRACTWe examined the relationships between calf productivity, anemia and Theileria orientalis sergenti infection from records of 109 Japanese shorthorn calves during a grazing period and we quantified the relative importance of the T. orientalis sergenti infection‐resistance criteria used. A decrease in average parasitemia (AvePara) and an increase in average packed cell volume (AvePCV) would cause a decrease in the number of drug treatments. An increase in AvePCV would decrease the number of drug treatments more efficiently than a decrease in AvePara. An increase in AvePCV would cause an increase in dairy gain, while a decrease in AvePara would cause a decrease in dairy gain. Therefore, an improvement in the capacity to control anemia development would improve T. orientalis sergenti infection resistance more efficiently than an improvement in the capacity to control parasitemia development.
Changes in the chemical composition of soil organic matter after application of compost
Authors: Leifeld J. , Siebert S. , Kögel‐Knabner I. 
Published: March 2003

SummaryIs the composition of soil organic matter changed by adding compost? To find out we incubated biowaste composts with agricultural soils and a humus‐free mineral substrate at 5°C and 14°C for 18 months and examined the products. Organic matter composition was characterized by CuO oxidation of lignin, hydrolysis of cellulosic and non‐cellulosic polysaccharides (CPS and NCPS) and 13C cross‐polarization magic angle spinning nuclear magnetic resonance (CPMAS 13C‐NMR) spectroscopy. The lignin contents in the compost‐amended soils increased because the composts contained more lignin, which altered little even after prolonged decomposition of the composts in soil. A pronounced decrease in lignin occurred in the soils amended with mature compost only. Polysaccharide C accounted for 14–20% of the organic carbon at the beginning of the experiment for both the compost‐amended soils and the controls. During the incubation, the relative contents of total polysaccharides decreased for 9–20% (controls) and for 20–49% (compost‐amended soils). They contributed preferentially to the decomposition as compared with the bulk soil organic matter, that decreased between < 2% and 20%. In the compost‐amended agricultural soils, cellulosic polysaccharides were decomposed in preference to non‐cellulosic ones. The NMR spectra of the compost‐amended soils had more intense signals of O–alkyl and aromatic C than did those of the controls. Incubation for 18 months resulted mainly in a decline of O–alkyl C for all soils. The composition of the soil organic matter after compost amendment changed mainly by increases in the lignin and aromatic C of the composts, and compost‐derived polysaccharides were mineralized preferentially. The results suggest that decomposition of the added composts in soil is as an ongoing humification process of the composts themselves. The different soil materials affected the changes in soil organic matter composition to only a minor degree.
Modelled changes in arctic tundra snow, energy and moisture fluxes due to increased shrubs
Authors: Liston Glen E. , Mcfadden Joseph P. , Sturm Matthew , Pielke Roger A. 
Published: March 2003

AbstractIn arctic tundra, shrubs can significantly modify the distribution and physical characteristics of snow, influencing the exchanges of energy and moisture between terrestrial ecosystems and the atmosphere from winter into the growing season. These interactions were studied using a spatially distributed, physically based modelling system that represents key components of the land–atmosphere system. Simulations were run for 4 years, over a 4‐km2 tundra domain located in arctic Alaska. A shrub increase was simulated by replacing the observed moist‐tundra and wet‐tundra vegetation classes with shrub‐tundra; a procedure that modified 77% of the simulation domain. The remaining 23% of the domain, primarily ridge tops, was left as the observed dry‐tundra vegetation class. The shrub enhancement increased the averaged snow depth of the domain by 14%, decreased blowing‐snow sublimation fluxes by 68%, and increased the snowcover's thermal resistance by 15%. The shrub increase also caused significant changes in snow‐depth distribution patterns; the shrub‐enhanced areas had deeper snow, and the non‐modified areas had less snow. This snow‐distribution change influenced the timing and magnitude of all surface energy‐balance components during snowmelt. The modified snow distributions also affected meltwater fluxes, leading to greater meltwater production late in the melt season. For a region with an annual snow‐free period of approximately 90 days, the snow‐covered period decreased by 11 days on the ridges and increased by 5 days in the shrub‐enhanced areas. Arctic shrub increases impact the spatial coupling of climatically important snow, energy and moisture interactions by producing changes in both shrub‐enhanced and non‐modified areas. In addition, the temporal coupling of the climate system was modified when additional moisture held within the snowcover, because of less winter sublimation, was released as snowmelt in the spring.
Influence of atmospheric CO2 enrichment on methane consumption in a temperate forest soil
Authors: Phillips Rebecca L. , Whalen Stephen C. , Schlesinger William H. 
Published: March 2003

AbstractRates of atmospheric CH4 consumption of soils in temperate forest were compared in plots continuously enriched with CO2 at 200 µL L−1 above ambient and in control plots exposed to the ambient atmosphere of 360 µL CO2 L−1. The purpose was to determine if ecosystem atmospheric CO2 enrichment would alter soil microbial CH4 consumption at the forest floor and if the effect of CO2 would change with time or with environmental conditions. Reduced CH4 consumption was observed in CO2‐enriched plots relative to control plots on 46 out of 48 sampling dates, such that CO2‐enriched plots showed annual reductions in CH4 consumption of 16% in 1998 and 30% in 1999. No significant differences were observed in soil moisture, temperature, pH, inorganic‐N or rates of N‐mineralization between CO2‐enriched and control plots, indicating that differences in CH4 consumption between treatments were likely the result of changes in the composition or size of the CH4‐oxidizing microbial community. A repeated measures analysis of variance that included soil moisture, soil temperature (from 0 to 30 cm), and time as covariates indicated that the reduction of CH4 consumption under elevated CO2 was enhanced at higher soil temperatures. Additionally, the effect of elevated CO2 on CH4 consumption increased with time during the two‐year study. Overall, these data suggest that rising atmospheric CO2 will reduce atmospheric CH4 consumption in temperate forests and that the effect will be greater in warmer climates. A 30% reduction in atmospheric CH4 consumption by temperate forest soils in response to rising atmospheric CO2 will result in a 10% reduction in the sink strength of temperate forest soils in the atmospheric CH4 budget and a positive feedback to the greenhouse effect.
Aurora‐B phosphorylates Histone H3 at serine28 with regard to the mitotic chromosome condensation
Authors: Goto Hidemasa , Yasui Yoshihiro , Nigg Erich A. , Inagaki Masaki 
Published: March 2003

AbstractBackground:  Histone H3 (H3) phosphorylation plays important roles in mitotic chromosome condensation. We reported that H3 phosphorylation occurs at Ser28, as well as at Ser10 during mitosis, at least in mammals. Aurora B was recently demonstrated to be responsible for Ser10 phosphorylation in S. cerevisiae, C. elegans, Drosophila and Xenopus egg extract.Results:  We compared the distribution of Aurora‐B with that of H3 phosphorylation. Aurora‐B was primarily localized in the heterochromatin of late G2 phase cells, where only Ser10 phosphorylation was observed. The treatment of such cells with calyculin A induced Ser28 phosphorylation in the Aurora‐B‐localized area. During prophase to metaphase, Aurora‐B was distributed in condensing chromosomes where Ser10 and Ser28 were phosphorylated. Aurora‐B can phosphorylate H3‐Ser10 and ‐Ser28 in nucleosomes in vitro. Transfection of a dominant‐negative mutant of Aurora‐B resulted in a reduction of H3 phosphorylation, not only at Ser10 but also Ser28, during mitosis.Conclusions:  With regard to mitotic chromosome condensation, Aurora‐B directly phosphorylated H3, not only at Ser10 but also at Ser28. The level of Ser28 phosphorylation is diminished to undetectable levels by PP1 phosphatase prior to entry into mitosis.
Dysregulation of angiotensin II synthesis is associated with salt sensitivity in the spontaneous hypertensive rat
Authors: HODGE G. , YE V. Z. C. , DUGGAN K. A. 
Published: March 2003

(1) Salt sensitive hypertension, which occurs as a result of treatment with nitric oxide synthase inhibitors, is associated with a loss of the usual down‐regulatory effect of dietary sodium on angiotensin II (Ang II) synthesis. In the spontaneous hypertensive rat (SHR), which suffers a relative NO deficiency, the hypertension is in part salt sensitive. We sought to determine therefore whether the salt sensitive component to the hypertension was associated with a loss of the regulatory effect of dietary sodium on Ang II synthesis.(2) Male SHR were placed on low, intermediate or high salt diets for 4 weeks and their blood pressure recorded. After 4 weeks, blood was collected for determination of renin, angiotensinogen, Ang I, Ang II and aldosterone concentrations, as well as ACE activity.(3) The increase in systolic blood pressure in rats on the high salt diet was significantly greater than in those on the low (P < 0.005) and intermediate salt diets (P < 0.0005). Plasma renin and aldosterone concentrations and ACE activity decreased with increasing dietary sodium. However, the concentrations of Ang II and angiotensinogen both increased in the rats on the high salt diet (Ang II: P < 0.05; angiotensinogen: P < 0.05).(4) We conclude that the hypertension in the SHR is in part salt sensitive and that this salt sensitive component is associated with a loss of the normal down‐regulatory effect of dietary sodium on Ang II and angiotensinogen synthesis.
Twenty‐four‐hour non‐invasive monitoring of systemic haemodynamics and cerebral blood flow velocity in healthy humans
Authors: DIAMANT M. , HARMS M. P. M. , IMMINK R. V. , VAN LIESHOUT J. J. , VAN MONTFRANS G. A. 
Published: March 2003

ABSTRACTAcute short‐term changes in blood pressure (BP) and cardiac output (CO) affect cerebral blood flow (CBF) in healthy subjects. As yet, however, we do not know how spontaneous fluctuations in BP and CO influence cerebral circulation throughout 24 h. We performed simultaneous monitoring of BP, systemic haemodynamic parameters and blood flow velocity in the middle cerebral artery (MCAV) in seven healthy subjects during a 24‐h period. Finger BP was recorded continuously during 24 h by Portapres and bilateral MCAV was measured by transcranial Doppler (TCD) during the first 15 min of every hour. The subjects remained supine during TCD recordings and during the night, otherwise they were seated upright in bed. Stroke volume (SV), CO and total peripheral resistance (TPR) were determined by Modelflow analysis. The 15 min mean value of each parameter was assumed to represent the mean of the corresponding hour. There were no significant differences between right vs. left, nor between mean daytime vs. night time MCAV. Intrasubject comparison of the twenty‐four 15‐min MCAV recordings showed marked variations (P < 0.001). Within each single 15‐min recording period, however, MCAV was stable whereas BP showed significant short‐term variations (P < 0.01). A day–night difference in BP was only observed when daytime BP was evaluated from recordings in the seated position (P < 0.02), not in supine recordings. Throughout 24 h, MCAV was associated with SV and CO (P < 0.001), to a lesser extent with mean arterial pressure (MAP; P < 0.005), not with heart rate (HR) or TPR. These results indicate that in healthy subjects MCAV remains stable when measured under constant supine conditions but shows significant variations throughout 24 h because of activity. Moreover, changes in SV and CO, and to a lesser extent BP variations, affect MCAV throughout 24 h.
Adenosine induces prolonged anti‐β‐adrenergic effects in guinea‐pig papillary muscle
Authors: ARVOLA L. , HASSAF D. , MELNIKOV A. L. , HELGESEN K. G. , YTREHUS K. 
Published: March 2003

ABSTRACTA sustained anti‐β‐adrenergic effect of adenosine has been reported. This study was initiated to investigate this topic and especially elucidate the role of protein kinase C (PKC). Contractile force amplitude and action potential duration at 90% repolarization (APD90) were measured in guinea‐pig papillary muscles before and after 5 min challenge with 5 nm isoproterenol. Protocols contained 30 min exposure to the test agents adenosine 33 μm (ado), adenosine + PKC‐inhibitor bisindolylmaleimide 20 nM (ado + BIM), PKC‐activator 1,2‐dioctanoyl‐sn‐glycerol 10 μm (DOG) and α‐agonist phenylephrine 5 μm (phe). Isoproterenol was given at the end of test exposure and after 15 min washout. Results are mean ± SEM of percentage‐change, P ≤ 0.05 considered significant and labelled *. The first isoproterenol challenge significantly increased contractile force (27 ± 7%*) in the control group. Responses in the test groups were 2 ± 4 (ado), 1 ± 5 (ado + BIM), 14 ± 4* (DOG), 0 ± 2% (phe). After washout of adenosine, DOG and phenylephrine, isoproterenol induced 3 ± 8 (ado), 23 ± 5* (ado + BIM), 13 ± 5* (DOG), 15 ± 7% (phe) increase in test groups compared with 22 ± 5%* increase in contractile force in the control group. After 45 min washout of adenosine the inotropic response was still significantly reduced compared with control (29 ± 4 vs. 79 ± 8%*). Isoproterenol stimulation shortened APD90 in controls at both time points (5 ± 1%* and 4 ± 1%*), with no significant shortening in test groups. Adenosine induces sustained anti‐β‐adrenergic effects on contractile force as well as APD90. A role for PKC in signal transduction is supported with respect to contractile force.
P2Y receptor‐induced EDHF vasodilatation is of primary importance for the regulation of perfusion pressure in the peripheral circulation of the rat
Authors: MALMSJÖ M. , CHU Z. M. , CROFT K. , ERLINGE D. , EDVINSSON L. , BEILIN L. J. 
Published: March 2003

ABSTRACTExtracellular nucleotides have been shown to induce vasodilatation of conductance arteries by release of the endothelium‐derived hyperpolarizing factor (EDHF). As small resistance arteries are of greater importance for blood pressure regulation, a whole rat mesenteric arterial bed preparation was used in the present study when evaluating the physiological relevance for EDHF in mediating nucleotide dilatation. Dilatory responses were examined after pre‐contraction with noradrenaline in the presence of 10 mM indomethacin. Adenosine‐5′‐O‐thiodiphosphate (ADPβS), adenosine triphosphate (ATP) and uridine triphosphate (UTP) induced vasodilatation (pEC50=6.5–7 and Emax=40–70%), while uridine diphosphate (UDP) was ineffective. Endothelium‐derived hyperpolarizing factor was studied in the presence of 0.5 mM Nϖ‐nitro‐L‐arginine (L‐NOARG). ADPβS and UTP induced strong and potent EDHF‐dilatations, while ATP only had a weak effect (Emax=25%). After P2X1 receptor desensitization with 10 μMαβ‐methylene‐adenosine triphosphate, the ATP response was significantly increased (Emax=65%). Putatively, this could be because of simultaneous activation of both endothelial P2Y receptors and P2X1 receptors on smooth muscle cells, which resulted in the release of EDHF and subsequent hyperpolarization, and depolarization, respectively. Nitric oxide (NO) was studied in the presence of 60 mM K+. ADPβS, ATP and UTP induced weak NO dilatations, suggesting a minor role for NO as compared with EDHF. In conclusion, extracellular nucleotides stimulate dilatation by activating P2Y1 and P2Y2/P2Y4 receptors, but not P2Y6 receptors. The dilatory responses are mediated primarily by EDHF in the peripheral vascular bed.
Adaptive stress response of glutathione and uric acid metabolism in man following controlled exercise and diet
Authors: Svensson M. B. , Ekblom B. , Cotgreave I. A. , Norman B. , Sjöberg B. , Ekblom Ö , Sjödin B. , Sjödin A. 
Published: March 2003

ABSTRACTErgometer cycling performance as well as acute exercise‐induced changes in the metabolism of energy‐intermediates and glutathione (GSH) were investigated in skeletal muscle (SM) of 15 healthy young male subjects (VO2max∼54.7 mL kg−1 min−1, age ∼25 years), before and after 3 days of controlled ‘ìoverload‐training’ in combination with either high (62% of energy intake) or low (26% of energy intake) dietary intake of carbohydrates. The intake of a carbohydrate‐rich diet clearly reduced the depletion of SM glycogen following the short‐term training period, paralleled with a positive effect on the endurance performance, but not on high‐intensity work‐performance. An ‘delayed over‐reaching effect’, defined as impaired work‐performance, was observed after 2.5 days of recovery from the short‐term training period, irrespective of the carbohydrate content of the diet and basal glycogen level in SM. Taken together, the main and novel findings of present investigation are: (1) an acute decrease of reduced GSH content and altered thiol‐redox homeostasis in SM induced by strenuous high‐intensity exercise; (2) an adaptive elevation of basal GSH level following the short‐term training period; (3) an adaptive decrease of basal GSH level following 2.5 days recovery from training; (4) evidence of a relationship between the SM fibre type, physical performance capacity and GSH turnover during acute bouts of exercise; and (5) no evident effect of the level of carbohydrate intake on metabolism of GSH or energy intermediates. Furthermore, the induction of acute oxidative stress in exercising human SM and the adaptive responses to training are suggested to provide a protective antioxidant phenotype to the exercising SM during periods with repeated intense intermittent training.
Effects of oestrogen and exercise on caspase‐3 activity in primary and secondary lymphoid compartments in ovariectomized mice
Authors: Patel H. , Hoffman‐Goetz L. 
Published: March 2003

ABSTRACTThis study investigated the effect of oestrogen exposure and exercise on caspase‐3 activity, a measure of apoptosis, in lymphocytes from the thymus, spleen, and lymph nodes in ovariectomized mice. Fifty‐nine female B6D2F1 mice were randomized to hormone and exercise conditions. Hormone treatment consisted of implantation with oestradiol pellets (0.72 mg oestradiol) or placebo pellets (0 mg) for 21 days following bilateral ovariectomy (OVX). Exercise consisted of a single treadmill exercise bout (26 m min−1, 6° slope, 90‐min) or sedentary condition. Mice were killed and the thymus, spleen and lymph nodes were removed for the determination of caspase‐3 expression by enzyme‐linked immunosorbent assay (ELISA), serum oestrogen levels by RIA, and tissue weights. Body weights were monitored throughout the study. In the thymus, oestrogen exposure, exercise and both treatments together were associated with higher caspase‐3 activity (P < 0.05) and lower thymus weights (P < 0.05). In contrast, oestrogen exposure and exercise treatment were not associated with greater caspase‐3 activity or change in tissue weight in secondary lymphoid tissues (spleen, lymph nodes). Oestrogen‐replaced OVX mice had a higher concentration of plasma oestradiol than placebo OVX mice (P < 0.05). Conclusion: The results suggest that oestrogen and treadmill exercise are associated with greater apoptosis, as measured by caspase‐3 activity, in the thymus but not in the spleen or lymph nodes. Clinical studies will be necessary to determine if women who take oestrogen have higher rates of apoptosis in primary lymphoid tissues and the significance of thymocyte apoptosis for maintenance of cellular immune function during the post‐menopausal years.
A rat resistance exercise regimen attenuates losses of musculoskeletal mass during hindlimb suspension
Authors: Fluckey J. D. , Dupont‐Versteegden E. E. , Montague D. C. , Knox M. , Tesch P. , Peterson C. A. , Gaddy‐Kurten D. 
Published: March 2003

ABSTRACTExposure to microgravity and/or spaceflight causes dramatic losses in both muscle and bone mass. In normal gravity, resistance exercise has been effectively used to increase muscle and bone mass. We tested a novel form of resistance exercise training using flywheel technology as a countermeasure to offset the loss of musculoskeletal mass during 4 weeks of adult rat hindlimb suspension (HS), an unloading model of microgravity. Male, Sprague–Dawley rats (6‐month old) were operantly conditioned to perform resistance exercise, and then randomly assigned to groups of sedentary control (CON), HS, and HS with resistance exercise training (HSRT; 2 sets of ∼21 repetitions, 3 days week−1 for 4 weeks during suspension). In soleus, HS resulted in lower (P < 0.05) muscle mass to body mass ratio (∼50% of controls) and rates of protein synthesis. HSRT significantly attenuated the loss of muscle mass in soleus muscle, and rates of protein synthesis for soleus were similar for HSRT and controls. There were no differences among groups for mass or rates of protein synthesis in extensor digitorum longus. In cancellous regions of the distal femur, HS resulted in significant reductions of bone mineral density (BMD), but this was restored to control levels with HSRT. Cortical regions of the femur were not different among HS, HSRT or control groups. Together, these data suggest that resistance training using flywheel technology may be a promising tool to attenuate losses of the musculoskeletal system during periods of hindlimb unloading.