bluuebunny/crossref_metadata_2025_split huggingface dataset:
Muscle fibre type, efficiency, and mechanical optima affect freely chosen pedal rate during cycling
Authors: Hansen E. A. , Andersen J. L. , Nielsen J. S. , Sjøgaard G. 
Published: March 2003

ABSTRACTThis study investigated the variation in freely chosen pedal rate between subjects and its possible dependence on percentage myosin heavy chain I (%MHC I) in m. vastus lateralis, maximum leg strength and power, as well as efficiency. Additionally, the hypothesis was tested that a positive correlation exists between percentage MHC I and efficiency at pre‐set pedal rates but not at freely chosen pedal rate. Twenty males performed cycling at low and high submaximal power output (∼40 and 70% of the power output at which maximum oxygen uptake (VO2max) was attained at 80 r.p.m.) with freely chosen and pre‐set pedal rates (61, 88, and 115 r.p.m.). Percentage MHC I as well as leg strength and power were determined. Freely chosen pedal rate varied considerably between subjects: 56–88 r.p.m. at low and 61–102 r.p.m. at high submaximal power output. This variation was only partly explained by percentage MHC I (21–97%) as well as by leg strength and power. Interestingly, %MHC I correlated significantly with the pedal rate at which maximum peak crank power occurred (r = −0.81). As hypothesized, %MHC I and efficiency were unrelated at freely chosen pedal rate, which was in contrast to a significant correlation found at pre‐set pedal rates (r = 0.61 and r = 0.57 at low and high power output, respectively). Conclusions: Subjects with high percentage MHC I chose high pedal rates close to the pedal rates at which maximum peak crank power occurred, while subjects with low percentage MHC I tended to choose lower pedal rates, favouring high efficiency. Nevertheless, the considerable variation in freely chosen pedal rate between subjects was neither fully accounted for by percentage MHC I nor by leg strength and power. Previously recognized relationships between percentage Type I (∼%MHC I) and efficiency as well as between pedal rate and efficiency were confirmed for pre‐set pedal rates, but for freely chosen pedal rate, these variables were unrelated.
Modifications to central neural circuitry during heart failure
Authors: Weiss M. L. , Kenney M. J. , Musch T. I. , Patel K. P. 
Published: March 2003

Abstract Aim:  During heart failure (HF), excess sodium retention is triggered by increased plasma renin–angiotensin–aldosterone activity and increased basal sympathetic nerve discharge (SND). Enhanced basal SND in the renal nerves plays a role in sodium retention. Therefore, as a hypothetical model for the central sympathetic control pathways that are dysregulated as a consequence of HF, the cental neural pathways regulating the sympathetic motor output to the kidney are reviewed in the context of their role during HF.Conclusion:  From these findings, a model of the neuroanatomical circuitry that may be affected during HF is constructed.
Bursting into space: alterations of sympathetic control by space travel
Authors: Eckberg D. L. ,   the Neurolab Autonomic Nervous System Team
Published: March 2003

AbstractAim:Astronauts return to Earth with reduced red cell masses and hypovolaemia. Not surprisingly, when they stand, their heart rates may speed inordinately, their blood pressures may fall, and some may experience frank syncope. We studied autonomic function in six male astronauts (average ± SEM age: 40 ± 2 years) before, during, and after the 16‐day Neurolab space shuttle mission.Method:We recorded electrocardiograms, finger photoplethysmographic arterial pressures, respiration, peroneal nerve muscle sympathetic activity, plasma noradrenaline and noradrenaline kinetics, and cardiac output, and we calculated stroke volume and total peripheral resistance. We perturbed autonomic function before and during spaceflight with graded Valsalva manoeuvres and lower body suction, and before and after the mission with passive upright tilt.Results:In‐flight baseline sympathetic nerve activity was increased above pre‐flight levels (by 10–33%) in three subjects, in whom noradrenaline spillover and clearance also were increased. Valsalva straining provoked greater reductions of arterial pressure, and proportionally greater sympathetic responses in space than on Earth. Lower body suction elicited greater increases of sympathetic nerve activity, plasma noradrenaline, and noradrenaline spillover in space than on Earth. After the Neurolab mission, left ventricular stroke volume was lower and heart rate was higher during tilt, than before spaceflight. No astronaut experienced orthostatic hypotension or pre‐syncope during 10 min of post‐flight tilting.Conclusion:We conclude that baseline sympathetic outflow, however measured, is higher in space than on earth, and that augmented sympathetic nerve responses to Valsalva straining, lower body suction, and post‐flight upright tilt represent normal adjustments to greater haemodynamic stresses associated with hypovolaemia.
Pathological sympathoexcitation: how is it achieved?
Authors: Elam M. , Sverrisdottir Y. B. , Rundqvist B. , Mckenzie D. , Gunnar Wallin B. , Macefield V. G. 
Published: March 2003

AbstractAim:  Congestive heart failure (CHF) and obstructive sleep apnoea syndrome (OSAS) are both associated with an intense sympathoexcitation, including an increased muscle sympathetic nerve activity (MSNA). We have studied the firing characteristics of single vasoconstrictor fibres to the muscle vascular bed in CHF and OSAS patients, at rest and during transient sympathoexcitatory stimuli, to elucidate the mechanisms by which vasoconstrictor output is augmented in these conditions.Results:  The main alternatives for augmenting sympathetic output are an increased firing frequency of individual nerve fibres and an increased recruitment of nerve fibres. Starting with the frequency alternative, the inherent bursting character of MSNA provides two possibilities to increase the firing of individual fibres: (1) by increasing the proportion of neural bursts in which the fibre is active (increased firing probability) and (2) by increasing the number of spikes a fibre generates per burst (increased multiple within‐burst firing). At rest and in cardiac sinus rhythm, an increased firing probability is seen in both CHF and OSAS patients, whereas increased multiple within‐burst firing is found in OSAS but not in CHF. In response to transient sympathoexcitatory stimuli (such as pre‐mature heart beats), both patient groups show marked shifts towards multiple within‐burst firing. Thus, both mechanisms for augmenting discharge frequency are operating in these two pathological conditions, but the firing characteristics at rest differ significantly. During recording sessions in sympathoexcited patients, we have encountered vasoconstrictor fibres that are active almost exclusively during periods of transient sympathoexcitation, while being virtually silent at rest. This suggests that recruitment of previously inactive vasoconstrictor fibres, the second main alternative for increasing vasoconstrictor output, contributes to transient sympathoexcitatory responses in these patients. Although it seems reasonable to assume that recruitment may also contribute to the resting level of MSNA in CHF and OSAS, this issue is difficult to resolve in microneurographic studies.Conclusion:  In conclusion, pathological sympathoexcitation appears to depend on both recruitment and increased firing frequency. A shift towards multiple within‐burst firing, at rest or in response to transient stimuli, may constitute a risk factor per se as it entails neural volleys with high instantaneous firing frequencies and consequently higher release of neurotransmitters.
The activity of single vasoconstrictor nerve units in hypertension
Authors: Mary D. A. S. G. , Stoker J. B. 
Published: March 2003

AbstractAim:  It has long been established from controlled experiments in anaesthetized animals that it is more accurate to quantify the mean frequency of efferent sympathetic nerve activity from single unit than from multi‐unit bursts recordings. More recently, sympathetic nerve hyperactivity has been reported in patients with essential hypertension (EHT) when using microneurographic recordings from peripheral efferent nerves. This review will focus on the mean frequency of single unit of muscle sympathetic nerve activity (s‐MSNA) in relation to that of multi‐unit bursts (MSNA) as obtained by microneurography in EHT.Results:  We have shown that the resting levels of s‐MSNA and MSNA were increased in uncomplicated EHT, white coat hypertension and in EHT complicated by left ventricular hypertrophy. There was a relatively greater increase in s‐MSNA than in MSNA in mild hypertension and in complicated EHT. We also found that both s‐MSNA and MSNA were increased to a similar extent in conditions known to affect reflexes emanating from the heart and influencing sympathetic output, such as acute myocardial infarction. In other preliminary studies, the increase of s‐MSNA in response to the discomfort of cold pressor test was greater than that of MSNA and this difference was abolished by the centrally sympatholytic agent moxonidine.Conclusion:  These results are consistent with the hypothesis that an increase in the mean frequency of central sympathetic discharge to the periphery (greater s‐MSNA than MSNA) is involved in the pathogenesis and complications of EHT. Target organ damage may in turn lead to an increase in overall sympathetic output (excessive MSNA increase) through the operation of peripheral reflex mechanisms.
Chemical quality of the burnt and non‐burnt grass layer in the Nylsvlei Nature Reserve, South Africa
Authors: DÖrgeloh Werner G. 
Published: March 2003

SummaryThe forage quality of the herbaceous layer in burnt and non‐burnt plant communities was determined seasonally to serve as a baseline for managing the food supply. The near‐infrared reflectance spectroscopy method and wet chemical analyses were applied to analyse the grass samples. Differences in forage quality were found between plant communities. The Sporobolus ioclados–Acacia tortilis Savanna had the highest forage quality throughout the year. Plant communities on the lithosols had a low forage quality. The highest total calcium and total phosphorus concentrations were found in the Eragrostis pallens–Burkea africana Savanna, total potassium in the plant communities on the lithosols, and total sodium in the Sporobolus ioclados–Acacia tortilis Savanna and floodplain. The most optimum Ca:P ratio was found in the Eragrostis pallens–Burkea africana Savanna when burnt and non‐burnt. In non‐burnt areas the highest K:Na ratio was found in the Sporobolus ioclados–Acacia tortilis Savanna.Burning increased the forage quality in some plant communities. In general, only percentage in vitro organic matter digestibility differed significantly between burnt and non‐burnt plant communities. The forage quality did not increase significantly in plant communities on lithosols and on vertisols. Mineral ratios did not differ between newly burnt plant communities. A low protein and mineral content in the winter forage should be countered with supplementary feeding or burning of grass to improve the condition of animals.
Structural analysis of the Chambura Gorge forest (Queen Elizabeth National Park, Uganda)
Authors: Grillini Carlo R. Lenzi , Orioli Lorenzo , Piussi Pietro , Kakuru Willy 
Published: March 2003

AbstractThe Chambura Gorge, part of the Queen Elizabeth National Park (QENP), is completely covered by a forest which so far has not been exploited and whose species, composition and structure are barely known. It was therefore of interest to analyse this area as a typical example of a primary natural forest and as a peculiar habitat inside the QENP ecosystem. The forest cover has a typical structure, distributed into layers, but the lower layer is locally poor of saplings belonging to a possible cohort of regeneration. This process is likely to be observable on a wider scale of analysis. None of the species reach their potential maximum height, as measured in other areas and in a typical rain forest. However, the vegetation of Chambura Gorge is very representative of the local edaphic conditions and microclimate. In the structural analysis no relationships were found between the diameters and heights of the observed trees, if considered all together. If considered individually, only the most abundant species, Cleistopholis patens, showed any relationship between diameter and height.
The impact of giraffe, rhino and elephant on the habitat of a black rhino sanctuary in Kenya
Authors: Birkett Alan 
Published: March 2003

AbstractThe habitat in an enclosed black rhino sanctuary, the Sweetwaters Game Reserve in Kenya, is being altered as populations of elephant, giraffe and black rhino increase. Height‐specific browse impact data were recorded for 1075 trees of the dominant species, the whistling thorn, Acacia drepanolobium. Rhinos and elephants browsed 18% of these trees in 1 year, including 5% that were killed or removed. The remaining trees were subjected to high levels of giraffe browse and low rainfall and grew by only 7.5 cm in a year. A mathematical model has been constructed that predicts how the number of trees ha−1 will change with time under different browsing impacts. The model compares recruitment rate with removal rate and estimates that the number of trees ha−1 will fall by 2% per year under the current browsing impact of black rhino (0.27 per km2), elephant (1.1 per km2) and giraffe (1.9 per km2). In 7 years, if the rhino and elephant populations continue to increase at the current rates, tree density will be falling by 5% per year and nearly one‐third of the trees will have been removed. These conditions are unsustainable and will result in habitat change and may affect rhino breeding. Several ways of alleviating the problem are discussed.
Clarithromycin increases the release of heat shock protein B from Helicobacter pylori
Authors: Tsuzuki T. , Ina K. , Ohta M. , Hasegawa T. , Nagasaka T. , Saburi N. , Ueda M. , Konagaya T. , Kaneko H. , Imada A. , Nishiwaki T. , Nobata K. , Ando T. , Kusugami K. 
Published: March 2003

Background:Clarithromycin (CAM) may have certain indirect effects on Helicobacter pylori (H. pylori) other than its inhibitory activity on bacterial growth, as indicated in other infections with Gram‐negative micro‐organisms. In the present study, we examined the effects of lower concentrations of CAM on the release of heat shock protein B (HspB), one of the major antigenic proteins from H. pylori cells, as well as the changes in humoral immune response and histological degree of antral gastritis in patients who received eradication therapy with CAM.Methods:The H. pylori strain 26695 and three CAM‐resistant clinical isolates were cultured in broth with and without CAM (2–500 ng/mL). Expression of H. pylori proteins was examined by two‐dimensional (2D)‐electrophoresis followed by N‐terminal amino acid sequencing. Changes in host immune response and histological degree of antral gastritis were monitored in patients with peptic ulcer disease who received H. pylori eradication therapy.Results:2D electrophoresis showed 26 spots in extracellularly released proteins with different profiles from those in cytoplasmic proteins. The release of HspB increased after incubation with CAM (30–500 ng/mL) in all three H. pylori clinical isolates tested. Patients with failed H. pylori eradication after triple therapy with CAM, but not those with failed eradication after dual therapy without CAM, showed an increase in serum IgG1 and IgG2 antibodies against HspB along with a decrease in the degree of neutrophil and H. pylori colonization density in tissue sections.Conclusions:CAM may induce a humoral immune response against H. pylori and a decrease in gastric mucosal inflammation through up‐regulation of the release of HspB from the bacteria in infected patients.
Monitoring activity in ulcerative colitis
Authors: Rizzello F. , Gionchetti P. , Venturi A. , Amadini C. , Romagnoli R. , Campieri M. 
Published: March 2003

SummaryThe monitoring of patients with ulcerative colitis is easier than in patients with Crohn's disease for several reasons: the severity of symptoms and activity of inflammation tend to run parallel in ulcerative colitis when involvement of the large bowel is more extensive. The easy accessibility of the colonic mucosa by endoscopic and histologic examination provides further information concerning the degree of inflammation. In severe attacks, the patient must be admitted to hospital and monitored carefully. Clinical and laboratory parameters (such as daily stools, CRP, fever, haemoglobin, albumin, etc.) and plain abdominal X‐ray are useful in monitoring the activity of the disease and to predict the outcome. In mild to moderate attacks, endoscopic and histologic evaluation are the best methods for choosing the appropriate treatment and for assessing response.
Monitoring the activity of Crohn's disease
Authors: Biancone L. , De Nigris F. , Del Vecchio Blanco G. , Monteleone I. , Vavassori P. , Geremia A. , Pallone* F. 
Published: March 2003

SummaryCrohn's disease is characterized by a chronic inflammation of the intestine of unknown aetiology. One of the main problems when treating patients with Crohn's disease, is the identification of patients undergoing early clinical relapse, for timely treatment and the possible prevention of complications. No sub‐clinical markers are currently available that predict relapse during remission. Several parameters have been proposed for this purpose. Although none have proven useful, growing evidence suggests a possible benefit in the clinical management of Crohn's disease. Among these, we may identify: clinical behaviour, the characteristics of the host, clinical activity, markers of intestinal inflammation and markers of immune activation. In particular, the possible relationship between cytokine pattern and the clinical behaviour of Crohn's disease has been addressed. Overall, these observations suggest that mucosal immune activation is a feature of Crohn's disease, and may persist in the form of activated immunocompetent cells during remission. On the basis of this evidence, studies are currently investigating whether the down‐regulation of immune activation markers is associated with clinical remission in Crohn's disease. It has been shown that higher mucosal levels of TNF‐α and an increased state of activation of lamina propria mononuclear cells in patients with inactive Crohn's disease, are significantly associated with an earlier clinical relapse of the disease. These observations suggest that a persistent local immune activation during remission may represent a marker of early clinical relapse of Crohn's disease.
Indication and type of surgery in Crohn's disease
Authors: Poggioli G. , Pierangeli F. , Laureti S. , Ugolini F. 
Published: March 2003

SummaryThe large majority of patients affected by Crohn's disease require surgery during their clinical history. Radical resection originally advocated for Crohn's disease does not decrease the recurrence rate, and repeated resections predispose patients to the development of short‐bowel syndrome. Over the last few years, conservative surgery has become accepted by many authors as a safe means of treating obstructive Crohn's disease. In this review article we analyse the efficacy and safety of conservative techniques, in comparison with resective surgery. Indications, advantages and technical aspects of resective and conservative surgery are reported.The experience with 489 patients treated for complicated or treatment refractory Crohn's disease in our Institution suggests that strictureplasty is a safe and effective procedure in many cases, as reported by other authors. The risk of cancer in areas of active disease as in stenosis treated with strictureplasty seems to be negligible. Resective surgery still represents the `gold standard' in patients with perforating Crohn's disease; however, conservative surgery, usually contraindicated in perforating Crohn's disease, can be advocated in patients with localized perforating disease presenting an actual risk of short bowel syndrome.
Drug‐induced hypochlorhydria causes high duodenal bacterial counts in the elderly
Authors: Pereira  , Gainsborough  , Dowling  
Published: March 2003

Background:Small bowel bacterial overgrowth secondary to drug‐induced hypochlorhydria may be of particular importance in the elderly, in whom anti‐ulcer drugs are commonly prescribed and the consequences of malabsorption may be severe.Methods:Duodenal aspirates were obtained from elderly individuals before (n=24) and during a 2‐month treatment course with either omeprazole (20 mg daily; n=8) or ranitidine (300 mg b.d.; n=6), and from six patients with small bowel bacterial overgrowth who had diarrhoea and malabsorption.Results:Before treatment, duodenal bacterial counts were normal (< 104 colony forming units/mL) in 23 elderly subjects (96%). However, six of 14 patients (43%) treated with omeprazole (5 of 8) or ranitidine (1 of 6) developed bacterial counts>  105 cfu/mL. All remained asymptomatic and had normal lactulose breath H2 profiles during treatment.Conclusion:Drug‐induced hypochlorhydria causes high duodenal bacterial counts in the elderly but, in the short term, this bacterial overgrowth is not associated with malabsorption.
Primary gastroduodenal prophylaxis with omeprazole for non‐steroidal anti‐inflammatory drug users
Authors: Cullen  , Bardhan  , Eisner  , Kogut  , Peacock  , Thomson  , Hawkey  
Published: March 2003

Aim:To investigate the efficacy of omeprazole 20 mg o.m. as primary prophylaxis against non‐steroidal anti‐inflammatory drug (NSAID)‐associated ulcer disease or dyspeptic symptoms.Methods:A parallel group study compared patients randomized to receive omeprazole 20 mg o.m. or placebo as co‐therapy with on‐going NSAID treatment, over 6 months, in 19 specialist centres in Ireland, Hungary, France, the UK and the USA. One hundred and sixty‐nine patients taking NSAIDs regularly, chronically and above defined minimum doses entered the trial. The main outcome measure was the development of gastric or duodenal ulcers detected endoscopically, the development of multiple erosions in the stomach or duodenum, or the onset of moderate or severe dyspeptic symptoms.Results:The estimated probability of remaining free of these end‐points for 6 months for patients taking omeprazole was 0.78 compared to 0.53 for placebo (P = 0.004). Fourteen patients receiving placebo (16.5%) developed 15 ulcers, comprising nine gastric and six duodenal ulcers, compared to three patients (3.6%) receiving omeprazole (all gastric ulcers). Logistic regression analysis showed that older patients were less likely, whilst those with rheumatoid arthritis were more likely, to remain free of NSAID‐associated problems.Conclusions:Omeprazole is an effective agent for gastroduodenal prophylaxis in patients taking NSAIDs. Its main effect is to reduce the rate of development of gastric and duodenal ulcers.
Acid suppression by omeprazole does not affect orally administered metronidazole bioavailability and metabolism in healthy male volunteers
Authors: David  , Silva C. M. F. Da , Mendes  , Ferraz  , Muscara  , Moreno  , Nucci G. De , Pedrazzoli  
Published: March 2003

Background:The addition of omeprazole to classical triple therapy for eradication of H. pylori may enhance compliance through reducing ulcer symptoms and side‐effects. The aim of this study was to investigate the effects of a 5‐day administration of omeprazole on metronidazole pharmacokinetics.Methods:Fourteen healthy male volunteers were selected. The study had an open, randomized, two‐period crossover design with a 21‐day washout period between the phases. Plasma concentrations of metron‐idazole and its hydroxy‐metabolite were measured by reversed‐phase HPLC with ultraviolet detection.Results:Administration of omeprazole did not affect the pharmacokinetic parameters of orally administered metronidazole.Conclusion:Our results indicate that short‐term treatment with omeprazole in healthy volunteers does not alter the extent or the rate of metronidazole absorption, and does not affect metronidazole clearance.