bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular sexing of Japanese cormorants used for traditional fishing on the Nagara River in Gifu City
Authors: INOUE‐MURAYAMA Miho , UEDA Yuko , YAMASHITA Tetsuji , NISHIDA‐UMEHARA Chizuko , MATSUDA Yoichi , MASEGI Toshiaki , ITO Shin’ichi
Published: March 2003

The Japanese cormorants used in traditional fishing in Japan are wild derived and their sex cannot be determined from their appearance. Applicability of molecular sex determination based on the size difference between CHD1Z and CHD1W introns was confirmed in male and female Japanese cormorants whose sexes had been ascertained by pathological autopsy. All of 21 birds of unknown sex reared by a cormorant fishing master were identified as males. The molecular sexing method will provide valuable information on sex differences of wild Japanese cormorants, including tameness, trainability, behavior and fishing capability, as well as for future trials involving artificial reproduction.
Effects of medium‐chain fatty acid‐cyclodextrin complexes on ruminal methane production in vitro
Authors: AJISAKA Noriko , MOHAMMED Nazimuddin , HARA Koji , MIKUNI Katsuhiko , HARA Kozo , HASHIMOTO Hitoshi , KUMATA Takako , KANDA Shuhei , ITABASHI Hisao
Published: March 2003

The purpose of the present study was to evaluate effects of medium‐chain fatty acid‐cyclodextrin (CD) complexes on ruminal methane and volatile fatty acid production, and protozoal activity in vitro. Medium‐chain fatty acid‐CDs used in this study were caprylic acid (C8)‐αCD or ‐βCD, capric acid (C10)‐αCD or ‐βCD, and lauric acid (C12)‐αCD or ‐βCD. A 60‐mL of diluted rumen fluid was incubated anaerobically at 38°C for 6 h with the addition of the complex (10–40 mg as fatty acid). Each of the fatty acid‐CDs reduced the number of protozoa, with the order C10 > C12 > C8, and βCD complexes were more effective than αCD complexes. Molar proportions of acetic acid remained unchanged with the addition of fatty acid‐CD, while that of propionic acid increased, being significant for C8‐αCD and βCD, and C10‐αCD and βCD (P < 0.05). Hydrogen production decreased by about 70% of control with the addition of 40 mg of C8 and C10‐CD, on the other hand, it tended to increase with the addition of C12‐CD in both αCD and βCD. Methane production decreased by about 20% with the addition of 40 mg of complexes, except for C10‐βCD, which significantly reduced methane production by about 60%. In conclusion, the addition of C8 or C10‐CD to ruminant diets may be effective in reducing methane production.
Effects of intracerebroventricular infusions of corticotropin‐releasing hormone in sheep
Authors: YAYOU Ken‐ichi , OTANI Humihiro , TAKUSARI Naozumi , UETAKE Katsuji , OKAMOTO Takashi
Published: March 2003

To provide new insights into the neural mechanisms of physiological and behavioral responses to stressors in sheep, acute changes in endocrine, autonomic and behavioral functions following 30 min infusions of ovine‐corticotropin‐releasing hormone (oCRH; 0, 0.5, 5 or 50 µg/0.5 mL of artificial cerebrospinal fluid/30 min) into the third ventricle of sheep (n = 7–8) were examined. Serial blood samples were collected through indwelling jugular catheters to determine plasma cortisol concentrations (CORT). Heart rate (HR) and rectal temperature (RT) were obtained via telemetry systems. The behaviors of the animal were monitored simultaneously. Intracerebroventricular infusions of CRH dose‐dependently induced an increase in CORT; there was a time–treatment interaction in CORT (P < 0.001). There was not a time–treatment interaction either in HR (P = 0.29) or in RT (P = 0.28). That RT showed a tendency to decrease with higher doses of CRH in sheep was in contradiction to previous reports in rats and pigs. As to changes in behavioral function, only the induction of bleating was marked. These results suggest that in physiological and behavioral responses of sheep to stressors, CRH regulates the increase in CORT and the induction of bleating. However, CRH might have little function in sympathetic nervous activation during physiological responses to stressors in sheep.
Lateritic and redoximorphic features in a faulted landscape near Manaus, Brazil
Authors: Fritsch E. , Montes‐Lauar C. R. , Boulet R. , Melfi A. J. , Balan E. , Magat P.
Published: March 2003

The soils and sediments of the uplands in the Manaus region are described and analysed along a representative cross‐section. There are two broad types of features, lateritic and redoximorphic. Their formation is linked to two main processes acting under contrasted hydrological regimes. The first process, acting under well‐drained conditions, is lateritization. It has transformed strongly weathered sediment into soil and led to depletion of silica (mainly quartz) as well as to relative accumulation of both kaolinite and iron oxides (haematite and goethite). Crystallographic changes observed in the latter have resulted from alternating dissolution and crystallization cycles without significant transfer of iron and alumina. However, in the uppermost soil, dissolution of kaolinite has prevailed over crystallization, leading to depletion of clay and the formation of tiny crystals of gibbsite disseminated throughout the groundmass. The second process results from the development of reducing conditions in groundwater giving redoximorphic features in lateritic soils and sediments. In the sediments, iron has been depleted by regional aquifers to form a pallid zone. In the soil, large amounts of iron and minor amounts of alumina, mainly from aluminous goethite, have been mobilized at first in small patches, which with further mobilization and vertical transfer of these elements have increased in size and have led to the formation of bleached horizons over thin iron pans. Iron has crystallized predominantly as haematite in the iron pans and alumina as large crystals of gibbsite in soil voids. Formation of impervious iron pans holds up fluctuating perched groundwater in the overlying horizons depending on rainfall events.

Neotectonic events (formation of uplifted blocks and small grabens) have markedly altered the hydrological regimes. In the uplifted blocks, the soil has been deeply truncated and iron loss has been checked in the uppermost sediment. By contrast, mobilization of iron has been initiated at various places in the soil of the small grabens. In this way tectonic events have checked mobilization of iron in sediments but activated it in soils, leaving spectacular fingerprints on the landscape.
Gas exchange and photosynthetic acclimation over subambient to elevated CO2 in a C3–C4 grassland
Authors: Anderson Laurel J. , Maherali Hafiz , Johnson Hyrum B. , Polley H. Wayne , Jackson Robert B.
Published: March 2003

Atmospheric CO2 (Ca) has risen dramatically since preglacial times and is projected to double in the next century. As part of a 4‐year study, we examined leaf gas exchange and photosynthetic acclimation in C3 and C4 plants using unique chambers that maintained a continuous Ca gradient from 200 to 550 µmol mol−1 in a natural grassland. Our goals were to characterize linear, nonlinear and threshold responses to increasing Ca from past to future Ca levels. Photosynthesis (A), stomatal conductance (gs), leaf water‐use efficiency (A/gs) and leaf N content were measured in three common species: Bothriochloa ischaemum, a C4 perennial grass, Bromus japonicus, a C3 annual grass, and Solanum dimidiatum, a C3 perennial forb. Assimilation responses to internal CO2 concentrations (A/Ci curves) and photosynthetically active radiation (A/PAR curves) were also assessed, and acclimation parameters estimated from these data. Photosynthesis increased linearly with Ca in all species (P < 0.05). S. dimidiatum and B. ischaemum had greater carboxylation rates for Rubisco and PEP carboxylase, respectively, at subambient than superambient Ca (P < 0.05). To our knowledge, this is the first published evidence of A up‐regulation at subambient Ca in the field. No species showed down‐regulation at superambient Ca. Stomatal conductance generally showed curvilinear decreases with Ca in the perennial species (P < 0.05), with steeper declines over subambient Ca than superambient, suggesting that plant water relations have already changed significantly with past Ca increases. Resource‐use efficiency (A/gs and A/leaf N) in all species increased linearly with Ca. As both C3 and C4 plants had significant responses in A, gs, A/gs and A/leaf N to Ca enrichment, future Ca increases in this grassland may not favour C3 species as much as originally thought. Non‐linear responses and acclimation to low Ca should be incorporated into mechanistic models to better predict the effects of past and present rising Ca on grassland ecosystems.
The impact of sampling frequency and sampling times on chamber‐based measurements of N2O emissions from fertilized soils
Authors: Smith Keith A. , Dobbie Karen E.
Published: March 2003

An automated closed‐chamber system was developed to measure N2O fluxes in the field. It was deployed at two N‐fertilized grassland sites in two successive years, together with replicated manual chambers, to investigate the spatial and temporal variability in fluxes, and the likely impact of sampling frequency on cumulative flux values. The automated system provided flux data at 8‐h intervals, while manual sampling was conducted at intervals of 3–7 days. The autochambers showed fluctuations in emissions not detected by manual sampling. However, integrated flux values based on the more intensive measurements were on average no more than 14% greater than those based on data from the autochambers that were obtained at the same time as manual sampling. This difference was not significant and well within the spatial variability determined with manual chambers. If daily sampling intervals were used immediately after fertilization, the agreement was closer still, increasing the confidence that can be placed in manual procedures. Diurnal variations in temperature and flux were small, and results from sampling at mid‐day were not significantly different from those based on early morning or evening sampling. Where diurnal fluctuations in temperature and flux are likely to be much larger, the autochamber/sampler system could prove very useful to quantify the effect.
Growth enhancement due to global atmospheric change as predicted by terrestrial ecosystem models: consistent with US forest inventory data
Authors: Joos Fortunat , Prentice I. Colin , House Joanna I.
Published: March 2003

Small reported growth enhancement factors based on analyses of forest inventory data from the eastern USA (Caspersen et al. 2000, Science, 290, 1148–1151) have been interpreted as evidence against CO2 fertilization in natural forests. We show to the contrary that growth enhancement in response to rising CO2, as found in ecosystems with experimental CO2 enrichment and implemented in terrestrial ecosystem models, is consistent with the data that have been presented within their uncertainties. Comparing forest inventory data with results of an empirical model of age‐dependent biomass accumulation, we find that growth enhancement of plausible magnitude could not be detected in these data, even if it were present. Although forest regrowth due to land‐use change is recognized as an important cause of carbon uptake by eastern US forests, forest inventory data do not provide a basis for eliminating environmentally induced growth enhancement as a substantial contribution to the global terrestrial carbon sink.
Replication fork block protein, Fob1, acts as an rDNA region specific recombinator in S. cerevisiae
Authors: Johzuka Katsuki , Horiuchi Takashi
Published: March 2003

Background: The analysis of homologous recombination in the tandemly repeating rDNA array of Saccharomyces cerevisiae should provide useful information about the stability of not only the rDNA repeat but also the abundant repeated sequences on higher eukaryotic genomes. However, the data obtained so far are not yet conclusive, due to the absence of a reliable assay for detecting products of recombination in the rDNA array.

Results: We developed an assay method to detect the products of unequal sister‐chromatid recombination (marker‐duplication products) in yeast rDNA. This assay, together with the circular rDNA detection assay, was used for the analysis. Marker‐duplication occurred throughout the rDNA cluster, preferentially between nearby repeat units. The FOB1 and RAD52 genes were required for both types of recombinant formation. FOB1 showed a gene dosage effect on not only the amounts of both recombinants, but also on the copy number of the repeat. However, unlike the RAD52 gene, the FOB1 gene was not involved in homologous recombination in a non‐rDNA locus. In addition, the marker‐duplication products were drastically decreased in the mre11 mutant.

Conclusion: Our data demonstrate that FOB1‐ and RAD52‐dependent homologous recombination cause the gain and loss of a few copies of the rDNA unit, and this must be a basic mechanism responsible for amplification and reduction of the rDNA copy number. In addition, FOB1 may also play a role in the copy number regulation of rDNA tandem repeats.
Meu10 is required for spore wall maturation in Schizosaccharomyces pombe
Authors: Tougan Takahiro , Chiba Yasuyoshi , Kakihara Yoshito , Hirata Aiko , Nojima Hiroshi
Published: March 2003

Background: Many genes are meiosis and/or sporulation‐specifically transcribed during this process. Isolation and analysis of these genes might help us to understand how meiosis and sporulation are regulated. For this purpose, we have isolated a large number of cDNA clones from Schizosaccharomyces pombe whose expression is up‐regulated during meiosis.

Results: We have isolated meu10+ gene, which encodes 416 amino acids and bears homology to SPS2 of Saccharomyces cerevisiae. A strain whose meu10+ gene has been deleted forms no viable spores. Thin‐section electron micrographs showed that the meu10Δ strain has abnormally formed spore walls, and then they disrupt, allowing cytoplasmic material to escape. The Meu10‐GFP fusion protein is localized to the spore periphery, thereafter returned to the cytoplasm after sporulation. Meu10‐GFP localization to the spore wall was almost normal in the bgs2Δ or chs1Δ mutants that lack 1,3‐β‐glucan or chitin, respectively. In contrast, 1,3‐β‐glucan is abnormally localized in meu10Δ cells. Meu10 has an N‐terminal domain with homology to the mammalian insulin receptor and a C‐terminal domain with a transmembrane motif. Mutants whose N‐terminal or C‐terminal domain was truncated were severely defective for sporulation.

Conclusions: Meu10 is a spore wall component and plays a pivotal role in the formation of the mature spore wall structure.
Effects of paternal drinking, conduct disorder and childhood home environment on the development of alcohol use disorders in a Thai population
Authors: Assanangkornchai Sawitri , Geater Alan F. , Saunders John B. , McNeil Donald R.
Published: March 2003

Aims

To identify influences on the development of alcohol use disorders in a Thai population, particularly parental drinking and childhood environment.

Design

Case–control study.

Setting

A university hospital, a regional hospital and a community hospital in southern Thailand.

Participants

Ninety‐one alcohol‐dependents and 77 hazardous/harmful drinkers were recruited as cases and 144 non‐ or infrequent drinkers as controls.

Measurements

Data on parental drinking, family demographic characteristics, family activities, parental disciplinary practice, early religious life and conduct disorder were obtained using a structured interview questionnaire. The main outcome measure was the subject's classification as alcohol‐dependent, hazardous/harmful drinker or non‐/infrequent drinker.

Findings

A significant relationship was found between having a drinking father and the occurrence of hazardous/harmful drinking or alcohol dependence in the subjects. Childhood factors (conduct disorder and having been a temple boy, relative probability ratios, RPRs and 95% CI: 6.39, 2.81–14.55 and 2.21, 1.19–4.08, respectively) also significantly predicted alcohol dependence, while perceived poverty and ethnic alienation was reported less frequently by hazardous/harmful drinkers and alcohol‐dependents (RPRs and 95% CIs = 0.34, 0.19–0.62 and 0.59, 0.38–0.93, respectively) than the controls. The relative probability ratio for the effect of the father's infrequent drinking on the son's alcohol dependence was 2.92 (95% CI = 1.42–6.02) and for the father's heavy or dependent drinking 2.84 (95% CI = 1.31–6.15).

Conclusions

Being exposed to a light‐drinking father increases the risk of a son's alcohol use disorders exhibited either as hazardous–harmful or dependent drinking. However, exposure to a heavy‐ or dependent‐drinking father is associated more uniquely with an increased risk of his son being alcohol‐dependent. The extent to which this is seen in other cultures is worthy of exploration.
Power output and muscle metabolism during and following recovery from 10 and 20 s of maximal sprint exercise in humans
Authors: BOGDANIS G.C. , NEVILL M.E. , LAKOMY H.K.A. , BOOBIS L.H.
Published: March 2003

On two separate days eight male subjects performed a 10‐ or 20‐s cycle ergometer sprint (randomized order) followed, after 2 min of recovery, by a 30‐s sprint. Muscle biopsies were obtained from the vastus lateralis at rest, immediately after the first sprint and after the 2 min of recovery on both occasions.The anaerobic ATP turnover during the initial 10 s of sprint 1 was 129 ± 12 mmol kg dry weight−1 and decreased to 63 ± 10 mmol kg dry weight−1 between the 10th and 20th s of sprint 1. This was a result of a 300% decrease in the rate of phosphocreatine breakdown and a 35% decrease in the glycolytic rate. Despite this 51% reduction in anaerobic ATP turnover, the mean power between 10 and 20 s of sprint 1 was reduced by only 28%. During the same period, oxygen uptake increased from 1.30 ± 0.15 to 2.40 ± 0.23 L min−1, which partially compensated for the decreased anaerobic metabolism. Muscle pH decreased from 7.06 ± 0.02 at rest to 6.94 ± 0.02 after 10 s and 6.82 ± 0.03 after 20 s of sprinting (for all changes P < 0.01). Muscle pH did not change following a 2‐min recovery period after both the 10‐ and 20‐s sprints, but phosphocreatine was resynthesized to 86 ± 3 and 76 ± 3% of the resting value, respectively (n.s. 10‐ vs. 20‐s sprint). Following 2 min of recovery after the 10‐s sprint subjects were able to reproduce peak but not mean power. Restoration of both mean and peak power following the 20‐s sprint was 88% of sprint 1, and was lower compared with that after the 10‐s sprint (P < 0.01). Total work during the second 30‐s sprint after the 10‐ and the 20‐s sprint was 19.3 ± 0.6 and 17.8 ± 0.5 kJ, respectively (P < 0.01). As oxygen uptake was the same during the 30‐s sprints (2.95 ± 0.15 and 3.02 ± 0.16 L min−1), and [Phosphocreatine] before the sprint was similar, the lower work may be related to a reduced glycolytic ATP regeneration as a result of the higher muscle acidosis.
Renal nerve stimulation restores tubuloglomerular feedback after acute renal denervation
Authors: KURKUS  , THORUP  , PERSSON
Published: March 2003

Renal nerves play an important role in the setting of the sensitivity of the tubuloglomerular feedback (TGF) mechanism. We recently reported a time‐dependent resetting of TGF to a lower sensitivity 3–4 h after acute unilateral renal denervation (aDNX). This effect persisted after 1 week, but was then less pronounced. To determine whether normal TGF sensitivity could be restored in aDNX kidneys by low‐frequency renal nerve stimulation (RNS), the following experiments were performed. Rats with aDNX were prepared for micropuncture. In one experimental group proximal tubular free flow (Pt) and stop flow pressures (Psf) were measured during RNS at frequencies of 2, 4 and 6 Hz. In another series of experiments the TGF sensitivity was evaluated from the Psf responses at different loop perfusion rates after 20 min of RNS at a frequency of 2 Hz. The maximal drop in Psf (ΔPsf) and the tubular flow rate at which half the maximal response in ΔPsf was observed (turning point, TP), were recorded. At RNS frequencies of 2, 4 and 6 Hz, Pt decreased from the control level of 14.1 ± 0.8–13.1 ± 1.0, 12.4 ± 1.1 and 11.2 ± 0.8 mmHg (decrease 21%, P < 0.05), respectively, while at zero perfusion and during RNS at 2 and 4 Hz Psf decreased from 42.5 ± 1.6 to 38.2 ± 1.4 and 32.8 ± 4.3 mmHg (decrease 23%, P < 0.05), respectively. The TGF characteristics were found to be reset from the normal sensitivity with TP of 19.0 ± 1.1 nL min–1 and ΔPsf of 8.7 ± 0.9 mmHg to TP of 28.3 ± 2.4 nL min–1 (increase 49%, P < 0.05) and ΔPsf of 5.8 ± 1.2 mmHg (decrease 33%) after aDNX. After 20 min of RNS at 2 Hz TP was normalized and ΔPsf was 33% higher. Thus the present findings indicate that the resetting of the TGF sensitivity that occurred 2–3 h after aDNX could be partially restored by 20 min of RNS at a frequency of 2 Hz. These results imply that renal nerves have an important impact on the setting of the sensitivity of the TGF mechanism.
Effects of moderate and intensive training on functional activity of central 5‐HT1B receptors in the rat substantia nigra
Authors: SEGUIN  , LISCIA  , GUEZENNEC  , FILLION
Published: March 2003

The efficacy of the selective 5‐HT1B receptor agonist CP 93,129 in inhibiting the forskolin‐stimulated adenylyl cyclase activity in the rat substantia nigra was reduced by both moderate and intensive prolonged training compared with sedentary resting rats. The concentration–response curves of the agonist were shifted to the right with a sixfold increase of the half‐maximal inhibitory concentration. A difference was observed between the two training exercises in regard to further changes in 5‐HT1B receptor sensitivity induced by an acute restraint stress. This manipulation did not affect the functional response of the 5‐HT1B receptors further in moderately trained rats, whereas an additional desensitization of the 5‐HT1B receptors was observed in intensively trained rats. These results strongly suggest the existence of regulation mechanisms altering the functional efficacy of 5‐HT1B receptors and, accordingly, affecting the serotonergic activity, since 5‐HT1B receptors modulate the neuronal release of the amine.
Receptor potential characteristics during direct stereocilia stimulation of isolated outer hair cells from the guinea‐pig
Authors: SHVAREV  , CANLON
Published: March 2003

The receptor potential as a function of stimulus amplitude and frequency was studied with the patch‐clamp technique in isolated outer hair cells (OHCs) with a length ranging from 30 to 87 μm during direct mechanical stimulation of the stereocilia. The amplitude and frequency of the stimulation were varied from 125 nm to 2 μm and from 100 Hz to 2.5 kHz, respectively. The mean resting membrane potential before stimulation was −64.25 ± 1.4 mV (mean ± SE, n = 26). Irrespective of the frequency used, stereocilia stimulation produced a combination of AC and DC responses, and both components showed saturation with increasing stimulation. Frequency responses appeared to be a function of intensity and resembled a low‐pass filter with a time constant ranging from 0.2 to 2.0 ms. With increasing stereocilia stimulation, the relative contribution of high frequencies to the AC component decreased, suggesting a decrease of the corner frequency. The saturated amplitude of the AC component for low‐frequency stimulation (100 Hz) was proportional to cell length and increased with a mean rate of 0.014 mV μm−1.

A relationship between the DC response of the receptor potential and the pre‐stimulus membrane potential was found. Recordings with more negative membrane potentials had greater DC components, while more depolarized recordings demonstrated smaller DC components. These fluctuations seemed to be defined by the interaction between the probe and stereocilia bundle and could be in the range of the transfer function for each cell.
In vivo31P NMR OSIRIS of bioenergetic changes in rabbit kidneys during and after ischaemia: effect of pretreatment with an indeno‐indole compound
Authors: SØRENSEN  , JONSSON  , PETTERSSON  , SCHERSTÉN  , SOUSSI
Published: March 2003

Changes in energy phosphates of rabbit kidneys subjected to ischaemia‐reperfusion have been measured in vivo with volume selective 31P NMR spectroscopy. The effects of pretreatment with a new lipid peroxidation inhibitor (indeno‐indol derivate – code name H290/51) on the bioenergetic changes were analysed. The left kidney was moved to a subcutaneous pocket to facilitate exact positioning over the surface coil. A 1H NMR image was acquired and a 3.5‐mL cube selected for 31P NMR spectra. 31P NMR spectra were recorded before occlusion of the left renal artery, during 1 h of ischaemia and 2 hours of reperfusion. Ischaemia induced drastic changes in the levels of inorganic phosphates and ATP as well as intracellular acidosis. A normalization was observed during reperfusion. Two hours after reperfusion significantly higher values for β‐ATP/Pi and intracellular pH were recorded in the animals pretreated with H290/51. The present technique allows quantitative analyses of changes in kidney bioenergetics in vivo during different experimental conditions. The importance of ischaemia‐reperfusion induced lipid peroxidation for mitochondrial function is emphasized.
Catecholamines in pericardial fluid of normotensive, spontaneously hypertensive and reserpine‐treated rats
Authors: KLEMOLA  , HUTTUNEN  , LAINE  , WECKSTRÖM  , HIRVONEN
Published: March 2003

In this study our aims were to investigate the presence and source of catecholamines in pericardial fluid of normotensive, reserpine‐treated and spontaneously hypertensive rats. We found that noradrenaline is the only detectable catecholamine present in rat pericardial fluid. The effect of reserpine 6, 12, and 24 h after pre‐treatment with 5 mg kg−1 (8.2 μmol kg−1) i.p. shows that the concentration of noradrenaline in pericardial fluid reflects the amount of noradrenaline released within the heart rather than the amount of noradrenaline in plasma. Using spontaneously hypertensive rats (SHR) as a model for primary hypertension we could show that the level of pericardial noradrenaline is approximately threefold in the pericardial fluid of the SHRs when compared to respective values of age‐matched normotensive Wistar–Kyoto rats (WKY), suggesting that there was an increased noradrenaline overflow in the hearts of the SHRs. In conclusion, determination of the noradrenaline concentration in the pericardial fluid might provide a new method for estimating the release of noradrenaline in the heart.
Time course of the inflammatory response to histamine and allergen skin prick test in guinea‐pigs
Authors: Evilevitch  , Wu  , Lindgren  , Greiff  , Norrgren  , Wollmer
Published: March 2003

Plasma exudation and vasodilatation are key microvascular features of acute inflammation. Exudation and vasodilatation responses in the weal area after skin prick testing with histamine are essentially completed within 30 min. There is evidence to suggest that vasodilatation lasts considerably longer after provocation with allergen, but there is no information on the duration of plasma exudation. The purpose of this study was to measure the time course of the microvascular inflammatory response in the skin after histamine and allergen provocation. Skin prick tests were performed with histamine, allergen (ovalbumin) or saline (control) on guinea‐pigs which were shaved on their backs. Radioactive 113mIn was used to label transferrin as a plasma tracer. Radioactivity was recorded from the superficial part of the skin by external detection of conversion electrons from the decay of 113mIn. The increase in count rate, corresponding to tracer accumulation by vasodilatation and/or plasma exudation, was used as a measure of the microvascular inflammatory response to skin prick test. The microvascular response was studied immediately and up to 30 min after provocation. The largest response to histamine and allergen occurred immediately after provocation. The exudative response then gradually declined to be absent after 25–30 min. Skin prick test with saline resulted in a small response of shorter duration. We conclude that the microvascular reaction to histamine as well as allergen provocation in guinea‐pig skin has a rapid onset and a duration of ≈30 min.
Effects of hydrogen peroxide on the guinea‐pig tracheobronchial mucosa in vivo
Authors: Greiff  , Erjefält  , Erjefält  , Wollmer  , Persson
Published: March 2003

Lumenal entry of plasma (mucosal exudation) is a key feature of airway inflammation. In airways challenged with histamine‐type mediators and allergen the mucosal exudation response occurs without causing epithelial derangement and without increased airway absorption. In contrast, reactive oxygen metabolites may cause mucosal damage. In this study, involving guinea‐pig airways, we have examined effects of H2O2 on airway exudation and absorption in vivo. Vehicle or H2O2 (0.1 and 0.5 M) was superfused onto the tracheobronchial mucosal surface through an oro‐tracheal catheter. 125I‐albumin, given intravenously, was determined in tracheobronchial tissue and in lavage fluids 10 min after challenge as an index of mucosal exudation of plasma. The tracheobronchial mucosa was also examined by scanning electron microscopy. In separate animals, 99mTc‐DTPA was superfused 20 min after vehicle or H2O2 (0.1 and 0.5 M) had been given. A gamma camera determined the disappearance rate of 99mTc‐DTPA from the airways as an index of airway absorption. The high dose of H2O2 (0.5 M) produced epithelial damage, increased the absorption of 99mTc‐DTPA (P < 0.001), and increased the exudation of plasma (P < 0.001). Notably, it appeared that all extravasated plasma had entered the airway lumen within 10 min. These data demonstrate that H2O2 differs from exudative autacoids such as histamine by causing both epithelial damage and plasma exudation responses. These data also agree with the view that the epithelial lining determines the rate of absorption and is responsible for the valve‐like function that allows lumenal entry of extravasated bulk plasma without any increased inward perviousness.
Haemodynamic changes in the cardiovascular system during the early phases of orthostasis
Authors: Huisman  , Pretorius  , Rooyen J.M. Van , Malan  , Eloff  , Laubscher  , Steyn
Published: March 2003

In this study, we monitored the changes in arterial blood pressure continuously in two groups of Caucasian men during normal passive orthostasis as well as reversed passive orthostasis. Group A consisted of a group of 23 younger men (16 ± 0.5 years) and group B consisted of 21 older men (62.9 ± 2.7 years). The normal passive orthostatic test and the reversed passive orthostatic test were used to induce blood pressure changes. We found that the temporary and initial changes in blood pressure during the normal and reversed orthostatic tests were significantly lower in the older group. Heart rate increases were also lower in the older group. These findings could be explained in terms of a reduced compliance of the thin walled venous blood vessels in the elderly.
Exogenous reactive oxygen and nitric oxide alter intracellular oxidant status of skeletal muscle fibres
Authors: Murrant  , Andrade  , Reid
Published: March 2003

To test whether exogenous oxidants alter intracellular oxidant levels in skeletal muscle fibres, we exposed rat diaphragm to donors of nitric oxide (NOx), reactive oxygen species (ROS) or hyperoxia, and monitored intracellular oxidant levels using a fluorescent probe. Fibre bundles were dissected from the diaphragm and loaded with 2’,7’‐dichlorodihydrofluorescein (DCFH); emissions were monitored using a fluorescence microscope. DCFH‐loaded muscles were exposed to either a NOx donor (1 m
M S‐nitroso‐N‐acetyl penicillamine, SNAP; 1 m
M sodium nitroprusside, SNP; 400 μM 1‐hydroxy‐2‐oxo‐3‐(N‐3‐methyl‐aminopropyl)‐3‐methyl‐1‐triazen, NOC‐7), an ROS donor (100 μM hydrogen peroxide, H2O2; 100 μM tert‐butyl hydroperoxide; 1 m
M hypoxanthine plus 0.01 U mL–1 xanthine oxidase, HXXO) or a range of PO2s (25, 60 or 95% O2 oxygenating Krebs–Ringer solution) for 40 min; time‐matched control bundles remained in Krebs–Ringer solution. Control muscles oxidized DCFH at a rate of 0.32 ± 0.1 greyscale units min–1. SNAP (766%), SNP (1244%), NOC‐7 (851%), H2O2 (543%), and HXXO (541%) increased DCFH oxidation from control levels. The increase in emissions caused by NOC‐7 and SNP were blunted by the NOx scavenger haemoglobin (1 μM). DCFH oxidation by HXXO was unaffected by 1000 U mL–1 superoxide dismutase but was significantly decreased by 1000 U mL–1 catalase and 1 m
M salicylate. PO2 had no effect on intracellular oxidant levels. Therefore, extracellular NOx and ROS can alter intracellular oxidant status in skeletal muscle fibres. These observations suggest that intrafibre oxidant levels could be the result of both intracellular and extracellular oxidant production.
Maximal strength and power characteristics in isometric and dynamic actions of the upper and lower extremities in middle‐aged and older men
Authors: Izquierdo  , Ibañez  , Gorostiaga  , Garrues  , Zúñiga  , Antón  , Larrión  , Häkkinen
Published: March 2003

Muscle cross‐sectional area of the quadriceps femoris (CSAQF), maximal isometric strength (handgrip test and unilateral knee extension/flexion), the shape of isometric force–time curves, and power–load curves during concentric and stretch–shortening cycle (SSC) actions with loads ranging from 15 to 70% of one repetition maximum half‐squat (1RMHS) and bench‐press (1RMBP) were examined in 26 middle‐aged men in the 40‐year‐old (M40) (mean age 42, range 35–46) and 21 elderly men in the 65‐year‐old age group (M65) (mean age 65, range 60–74). Maximal bilateral concentric (1RMHS and 1RMBP), unilateral knee extension (isometric; MIFKE and concentric; 1RMKE) strength and muscle CSA in M65 were lower (P < 0.001) than in M40. The individual values of the CSAQF correlated with the individual values of maximal concentric 1RMHS, 1RMKE and MIFKE in M65, while the corresponding correlations were lower in M40. The maximal MIFKE value per CSA of 4.54 ± 0.7 N m cm–2 in M40 was greater (P < 0.05–0.01) than that of 4.02 ± 0.7 N m cm–2 recorded in M65. The maximal rate of force development of the knee extensors and flexors in M65 was lower (P < 0.01–0.001) and the heights in squat and counter‐movement jumps as much as 27–29% lower (P < 0.001) than those recorded in M40. M65 showed lower (P < 0.001) concentric power values for both upper and lower extremity performances than those recorded for M40. Maximal power output was maximized at the 30–45% loads for the upper extremity and at the 60–70% loads for the lower extremity extensors in both age groups. Muscle activation of the antagonists was significantly higher (P < 0.01–0.001) during the isometric and dynamic knee extension actions in M65 than in M40. The present results support a general concept that parallel declines in muscle mass and maximal strength take place with increasing age, although loss of strength may vary in both lower and upper extremity muscles in relation to the type of action and that ageing may also lead to a decrease in voluntary neural drive to the muscles. Explosive strength and power seem to decrease with increasing age even more than maximal isometric strength in both actions but power was maximized at the 30–45% loads for the upper and at the 60–70% loads for the lower extremity action in both age groups. High antagonist muscle activity may limit the full movement efficiency depending on the type of muscle action, testing conditions and the velocity and/or the time duration of the action, especially in the elderly.
Hip fracture patients, a group of frail elderly people with low bone mineral density, muscle mass and IGF‐I levels
Authors: Hedström
Published: March 2003

Elderly women with hip fractures constitute an increasing group of patients in many western countries. The most significant of many factors contributing to the incidence of hip fractures are neuromuscular impairment and low bone mineral density (BMD). Both bone mass and muscle strength decrease during ageing as well as growth hormone (GH) and the anabolic, insulin‐like growth factor I (IGF‐I). We have found a lower IGF‐I level and lower bone and lean body mass in hip fracture patients than in an age‐matched group of patients. This sign of catabolism seems to continue postoperatively, with a significant decrease of both BMD and lean body mass possibly indicating GH/IGF‐I therapy together with adequate nutrition to preserve bone and muscle losses in elderly patients with hip fractures.
Mode of nitric oxide action on the renal vasculature
Authors: Kurtz  , Götz  , Hamann  , Sandner
Published: March 2003

Our study aimed to characterize the essential cellular pathways along which nitric oxide (NO) exerts its well‐known vasodilatatory properties in the kidney. Using the isolated perfused rat kidney model we examined the roles of potassium channels, cGMP‐protein kinase activity and cAMP‐phosphodiesterases (PDE) in the effect of NO on renovascular resistance. We found that neither potassium channel activity nor G‐kinase activity was essential for the vasodilatatory effect of NO. The effect of NO, however, was essentially mimicked by pharmacological inhibition of PDE‐3, which is a cGMP‐inhibitable PDE. As PDE‐3 is strongly expressed in renal preglomerular vessels and NO stimulates cGMP formation in renal vessels, it appears likely that inhibition of cAMP degradation and consequently the cAMP pathway are crucially involved in mediating the effects of NO on renal vascular resistance.
Differentiation of vasoactive renal sympathetic nerve fibres
Authors: Dibona
Published: March 2003

Activation of renal sympathetic nerves produces marked changes in renal haemodynamics, tubular ion and water transport and renin secretion. This review examines information indicating that these effects are mediated by functionally specific groups of renal sympathetic nerve fibres separately innervating the renal vessels, tubules and juxtaglomerular granular cells.
Interaction between nitric oxide and oxygen radicals in regulation of tubuloglomerular feedback
Authors: Wilcox  , Welch
Published: March 2003

NADPH oxidase, nitric oxide synthase (NOS) and cyclooxygenase are oxidases that are expressed in the juxtaglomerular apparatus (JGA) or blood vessels and can generate oxygen radicals (O−2) during partial reduction of molecular oxygen. O−2 interacts rapidly and irreversibly with nitric oxide (NO) to yield peroxynitrite (ONOO–), thereby restricting the half‐life, diffusion distance and bioactivity of NO in tissues. NO generated by a neuronal (n) NOS isoform that is heavily expressed in macula densa (MD) cells, is generated during NaCl reabsorption at the MD and blunts the expression of the tubuloglomerular feedback (TGF) response. Therefore, we tested the hypothesis that O−2 formed in the JGA of the normal rat limits NO signalling. Tempol is a membrane‐permeable superoxide dismutase (SOD) mimetic. Maximal TGF responses were assessed from the fall in proximal stop flow pressure during orthograde perfusion of artificial tubular fluid (ATF) into the loop of Henle. Microperfusion of tempol (10–4 M) into the efferent arteriole (EA) of Wistar–Kyoto rats blunted maximal TGF response (8.2 ± 0.4 vs. 6.4 ± 0.4 mmHg; n=8; P < 0.05). Graded doses of the NO donor compound, S‐nitroso‐acetylpenicillamine (SNAP; 10–7–10–4 M) microperfused into the lumen of the MD produces graded buffering of TGF. During EA microperfusion of tempol, responses to luminal SNAP at 10–6 M and greater were enhanced significantly (P < 0.05 or <0.01). In conclusion, O−2 generated in the JGA can be metabolized by a membrane‐permeable SOD mimetic. O−2 enhances the basal TGF response and limits NO signalling from the macula densa. Therefore, O−2 and NO interact in the JGA to modulate the TGF response.
Immunomodulation by 8‐week voluntary exercise in mice
Authors: Sugiura  , Sugiura  , Nishida  , Inaba  , Mirbod  , Iwata
Published: March 2003

This study was designed to evaluate the effects of voluntary exercise on macrophage and lymphocyte functions in mice. Male A/He inbred mice aged 19 weeks were divided into two groups: a group given voluntary exercise and a control group (n = 10 in each group). Exercise consisted of spontaneous running in wheels for 8 weeks (3 days week–1). Glucose consumption of peritoneal macrophages in the exercise group during incubation up to 72 h was significantly higher than that in the control group (70 and 13%, respectively). Also, activities of acid phosphatase (APH) (10.75 ± 0.37 IU), β‐glucuronidase (GLU) (1.55 ± 0.07 IU) and lactate dehydrogenase (LDH) (43.3 ± 0.7 IU) in the peritoneal macrophages in the exercise group was significantly increased (P < 0.01). Compared with the control group, the exercise group had a significant increase of about twofold in macrophage production of nitric oxide (NO2–) stimulated by lipopolysaccharide (LPS) (11.1 ± 0.1 vs. 5.9 ± 0.1 μM mL–1 in exercise and control groups, respectively; P < 0.01). Stimulation indices both by concanavalin A (Con A) and phytohaemagglutinin were also significantly higher in the exercise group (P < 0.01). A significant increase in the splenocyte production of interleukin‐2 (IL‐2) stimulated by Con A was noticed in the exercise group (354.1 ± 28.8 vs. 218.9 ± 23.5 pg mL–1 in exercise and control groups, respectively; P < 0.01). These findings suggest that voluntary exercise enhances not only macrophage function but also lymphocyte responsiveness in mice. In the studies of voluntary exercise, evaluation of NO2– production, as an indicator of macrophage function, is recommended.
Integration of blood flow control to skeletal muscle: key role of feed arteries
Authors: Segal S.S.
Published: March 2003

Blood flow control reflects dynamic, integrated changes in the diameter of vessels that comprise resistance networks. Vasoconstriction and vasodilation can travel rapidly along the vessel wall via the conduction of electrical signals between endothelial and/or smooth muscle cells through gap junctions. Within the hamster cheek pouch, these conducted responses reflect complementary mechanisms for co‐ordinating both increases and decreases in arteriolar diameter. In the hamster retractor muscle, vasodilation also conducts along arterioles and into feed arteries, yet vasoconstriction appears constrained to the site(s) of smooth muscle activation. Thus, mechanisms for co‐ordinating vasomotor control in resistance networks can vary between tissues that differ in structure and function. The resistance vessels of the retractor (and other skeletal) muscle are richly innervated by sympathetic nerves, which are absent from the cheek pouch. Propagation along sympathetic nerves rapidly co‐ordinates smooth muscle cell contraction throughout the resistance network by releasing noradrenaline along the innervation pathway. Passive extension of the retractor muscle activates periarteriolar sympathetic nerves. This activity propagates antidromically into feed arteries and may complement the central (autonomic) vasoconstrictor response to exercise. In a reciprocal manner, muscle contraction evokes arteriolar dilation that is conducted (i.e. ‘ascends’) into feed arteries and may thereby counteract sympathetic vasoconstriction. With feed arteries anatomically positioned to control blood flow into skeletal muscle, the integration of dilator and constrictor stimuli in these vessels is a key determinant of muscle blood flow during exercise.
Purinergic activation of BK channels in clonal kidney cells (Vero cells)
Authors: Hafting T. , Sand O.
Published: March 2003

We have studied the activation of a high‐conductance channel in clonal kidney cells from African green monkey (Vero cells) using patch‐clamp recordings and microfluorometric (fura‐2) measurements of cytosolic Ca2+. The single‐channel conductance in excised patches is 170 pS in symmetrical 140 mM KCl. The channel is highly selective for K+ and activated by membrane depolarization and application of Ca2+ to the cytoplasmatic side of the patch. The channel is, thus, a large‐conductance Ca2+‐activated K+ channel (BK channel). Cell‐attached recordings revealed that the channel is inactive in unstimulated cells. Extracellular application of less than 0.1 μM ATP transiently increased the cytosolic Ca2+ concentration ([Ca2+]i) to about 550 nM, and induced membrane hyperpolarization caused by Ca2+‐activated K+ currents. ATP stimulation also activated BK channels in cell‐attached patches at both the normal‐resting potential and during membrane hyperpolarization. The increase in [Ca2+]i was owing to Ca2+ release from internal stores, suggesting that Vero cells express G‐protein‐coupled purinergic receptors (P2Y) mediating IP3‐induced release of Ca2+. The P2Y receptors were sensitive to both uracil triphosphate (UTP) and adenosine diphosphate (ADP), and the rank of agonist potency was ATP >> UTP ≥ ADP. This result indicates the presence of both P2Y1 and P2Y2 receptors or a receptor subtype with untypical agonist sensitivity. It has previously been shown that hypotonic challenge activates BK channels in both normal and clonal kidney cells. The subsequent loss of KCl may be an important factor in cellular volume regulation. Our results support the idea of an autocrine role of ATP in this process. A minute release of ATP induced by hypotonically evoked membrane stretch may activate the P2Y receptors, subsequently increasing [Ca2+]i and thus causing K+ efflux through BK channels.
Effect of cholera toxin on passive transepithelial transport of 51Cr‐ethylenediaminetetraacetic acid and 14C‐mannitol in rat jejunum
Authors: Fihn B.‐M. , Sjöqvist A. , Jodal M.
Published: March 2003

Intestinal fluid secretion, mainly derived from the crypts, induced, for example, by cholera toxin, decreases the passive transport of small hydrophilic molecules into the lumen. However, the effect of the fluid secretion on the passive absorption of these substances and thus on the permeability of the villus absorptive area is not known. Therefore, the transport rates of 51Cr‐ethylenediaminetetraacetic acid (EDTA) and 14C‐mannitol from lumen to plasma and from plasma to lumen were recorded in jejunal loops of anaesthetized rats during cholera toxin‐induced fluid secretion in the absence and presence of glucose in the intestinal lumen and expressed as clearance (μL (min g)−1). The results showed that the cholera toxin induced fluid secretion and abolished the passive absorption of 51Cr‐EDTA both in the absence and presence of luminal glucose during a high perfusion rate (0.5 mL min−1). The clearance of mannitol was also inhibited at the low perfusion rate (0.2 mL min−1) with the glucose‐free perfusate but only reduced with the glucose perfusate. The results show that mechanisms activated by cholera toxin inhibit the passive absorption of inert hydrophilic substances. This is proposed to be mainly caused by a reduction in the accessibility of the villus epithelium to the luminal content. Furthermore, the secretion seems predominantly to inhibit the passive absorption at the basal parts of the villus while the absorption rate at the villus tips is better preserved. The results also show that the intestinal absorption and secretion of fluid takes place at different locations (villus and crypts, respectively).