bluuebunny/crossref_metadata_2025_split huggingface dataset:
Behaviour of the adrenergic cardiovascular drive in atrial fibrillation and cardiac arrhythmias
Authors: Grassi Guido , Seravalle Gino , Bertinieri Giovanni , Mancia Giuseppe 
Published: March 2003

AbstractAim:  Animal studies have conclusively shown that the sympathetic nervous system plays a major role not only in regulating sinus node activity but also in promoting cardiac rhythm alterations. Less univocal and often circumstantial have been the evidences collected on this issue in humans. However, the introduction of the microneurographic technique in clinical research has allowed to gain new important insights on the role of neuroadrenergic factors in the pathophysiology of cardiac arrhythmias.Methods:  The present paper will review the results of microneurographic studies performed by our group and others in the field of cardiac rhythm disturbances by addressing three specific issues. First it will examine the relationships between heart rate and muscle sympathetic neural outflow in a variety of cardiovascular diseases characterized by sympathetic activation. This will be followed by an analysis of the behaviour of the sympathetic nerve traffic responses to paroxysmal atrial fibrillation. Finally, the sympathetic adjustments to spontaneously occurring or artificially induced pre‐mature ventricular contractions will be highlighted.
Vegetation changes during a 36‐year period in northern Chobe National Park, Botswana
Authors: Mosugelo David K. , Moe Stein R. , Ringrose Susan , Nellemann Christian 
Published: March 2003

AbstractChanges in vegetation cover in northern Chobe National Park (Botswana) were assessed using aerial photographs from 1962, 1985 and 1998, with subsequent ground proofing. In addition, cumulative browsing by elephants and the occurrence of fire scars were recorded on random vegetation sites within shrubland (n = 20) and mixed woodland (n = 20). Coverage of woodland vegetation decreased from 60% to 30% between 1962 and 1998, while shrubland vegetation increased from 5% to 33% during the same period. During the study period, woodland has gradually retreated away from the river front. While riparian forest covered a continuous area along the riverfront in 1962, only fragments were left in 1998. We found a significant decrease in browse use with increasing distance to the Chobe river for Combretum apiculatum, Combretum elaeagnoides, Combretum mossambicense and other woody plants combined (all P < 0.0001). The occurrence of fire (P < 0.0001) and basal area (P < 0.0001) were positively related to distance to the river. Elephant browsing occurred on >70% of available stems within 2 km from the river, while less than 20% of the trees had fire scars in the same zone. Beyond 7 km from the river, elephant browsing was reduced to >50% of available stems, while more than 50% of the trees had fire scars. The density of any of the shrubs was not related to distance to the river neither within shrubland (all P > 0.05) nor within mixed woodlands (all P > 0.05).
Population fluctuations in relation to seasonal habitat preferences of the Swainson's spurfowl, Pternistis swainsonii
Authors: Jansen R. , Crowe T. M. 
Published: March 2003

AbstractCounts on Swainson's spurfowl Pternistis swainsonii were made during 1998–1999 within an intensive, fine‐grained, agricultural landscape to estimate population parameters, seasonal dispersion and habitat preferences. Radio‐transmitters were fitted to four birds to note habitat use and home ranges within the Summer breeding season. During Winter, population densities peaked, and birds exploited agricultural crops extensively. At the onset of Spring, densities dropped as birds paired to establish non‐overlapping breeding territories over a number of habitats with apparently sufficient cover and ‘natural’ food. Expanding grazed grassland appears to be the greatest threat to Swainson's spurfowl due to a lack of cover and food. The matrix of habitats within the landscape plays important roles in the success of this opportunistic spurfowl. Agricultural crops in the Winter sustain the population until the following Summer when natural savanna and ungrazed grasslands provide complementary foraging, nesting and roosting sites.
Sexual segregation in habitat use by elephants in Chobe National Park, Botswana
Authors: Stokke Sigbjørn , Du Toit Johan T. 
Published: March 2003

AbstractWe report on a study conducted on free‐ranging African elephants in the woodlands of northern Botswana. We compared bull groups and family units with regard to (1) their patterns of habitat use and (2) their ranging distances from perennial water sources. During the dry season, adult males frequented more habitat types than family units, whereas family units used a wider diversity of habitats than bulls during the wet season. Bulls roamed widely (>10 km) from perennial drinking water in the dry season, when family units congregated within 3.5 km of the rivers. During the wet season, when ephemeral pans were abundant, all elephant groups were found at intermediate distances (5 km) from the rivers. The spacing of elephants in the dry season is consistent with sexual segregation but we reject the hypothesis that this is an outcome of indirect competition for food, because our concurrent studies on elephant feeding ecology found no evidence for intraspecific competition. Instead, we propose that most adult male elephants space themselves to avoid conflict with musth bulls and roam widely in the dry season between discretely distributed feeding ‘hotspots’. The small proportion of males that are in musth remain close to family units to maximize mating opportunities, and family units are unable to range far from water in the dry season. This is due to (1) comparatively high rates of water turn‐over among juveniles and lactating cows and (2) the reduced mobility of neonates.
Association between gastric myoelectrical activity and intraluminal nitric oxide
Authors: Shiotani A. , Iguchi M. , Inoue I. , Magari H. , Yanaoka K. , Tamai H. , Kitauchi S. , Ichinose M. 
Published: March 2003

Background:We have previously shown that the intraluminal concentration of NO in H. pylori‐positive patients is significantly reduced compared to that in H. pylori‐negative patients.Aim:The aim of this study was to evaluate the effect of H. pylori infection on gastric motor activity in relation to the level of NO and nitrite in the stomach in humans.Methods:Thirty‐two H. pylori‐negative and 32 H. pylori‐positive patients with dyspepsia were studied. Gastric myoelectrical activity was recorded for 24 h using surface electrogastrography. Intraluminal gas and juice were endoscopically collected from the stomach to determine NO and nitrite and nitrate (NOx) levels using a chemiluminescence system.Results:The percentage of tachygastria in the morning preprandial state was significantly higher (P=0.005) in H. pylori‐positive than ‐negative patients. In H. pylori‐negative patients, there was a significant positive correlation between NO levels and the percentage of bradygastria (r=0.56, P=0.001) and a significant negative correlation between NOx levels and the percentage of normal electrical activity (r=− 0.57, P=0.001) in the preprandial state.ConclusionsGastric motor activity is associated with NO and NOx levels in the gastric lumen. H. pylori infection may play a role in the pathogenesis of abnormal gastric myoelectrical activity.
Inhibition of proliferation of gastric epithelial cells by a cyclooxygenase 2 inhibitor, JTE522, is also mediated by a PGE2‐independent pathway
Authors: Hirose M. , Miwa H. , Kobayashi O. , Oshida K. , Misawa H. , Kurosawa A. , Watanabe S. , Sato N. 
Published: March 2003

Background:Cyclooxygenase‐2 (COX‐2) is one of the rate‐limiting enzymes for prostaglandin synthesis from arachidonic acid. Although it is known that inhibition of cyclooxygenase activity delays ulcer healing, the regulatory relationship between COX‐2 and its metabolites in gastric epithelial cell proliferation is not well known.Aim:To investigate whether COX‐2 has an effect on gastric mucosal cell proliferation and further studied whether such effect is mediated only by prostaglandin E2 (PGE2), a representative metabolite of arachidonates in the gastric mucosa.Methods:Artificial wounds of defined area size were created on complete monolayer cell sheets of isolated rat gastric epithelial cells and rat gastric cell line RGM1 under the addition of arachidonic acid or a COX‐2 selective inhibitor, JTE522. Repair of wounds was assessed by monitoring wound size, with cell proliferation detected using 5‐bromodeoxyuridine staining. Quantity of secreted PGE2 was measured by enzyme immunoassay.Results:Stimulation of foetal calf serum increased the expression of COX‐2 protein and inhibition of COX‐2 retarded wound healing with reduction of cell proliferation. Arachidonic acid increased PGE2 production and accelerated restoration. Combination of JTE522 and arachidonic acid resulted in a marked retardation of wound healing compared to the control, but JTE522 did not completely suppress the increase in cellular PGE2 content following the addition of arachidonate.Conclusions:The difference in the effects of JTE522 on PGE2 production and on wound healing suggest that the involvement of COX‐2 in gastric epithelial cell proliferation is not mediated solely by PGE2.
Wine stimulates gastric acid secretion in isolated rabbit gastric glands via two different pathways
Authors: Matsuno K. , Tomita K. , Okabe S. 
Published: March 2003

Background & aims:Alcoholic beverages such as beer and wine are well known to potently stimulate gastric acid secretion, most probably through an increase in circulating gastrin level. The present study examined whether or not wine stimulates gastric acid secretion by a direct effect on parietal cells, enterochromaffin‐like (ECL) cells or both.Methods:Gastric mucosa was isolated from female Japanese white rabbits and gland specimens were prepared by the collagenase digestion method. Acid secretion was assessed by gland accumulation of [14C] aminopyrine. The effects of red wine, ethanol, non‐alcoholic wine and drugs were determined by incubating gastric glands with aminopyrine. Radioactivity in solubilized glands was determined by a liquid scintillation counting.Results:Neither wine nor ethanol (diluted 1 : 102 to 1 : 104) had any effect on gastric acid secretion, whereas non‐alcoholic wine stimulated acid secretion in a dose‐dependent manner. All substances, however, significantly stimulated gastric acid secretion in IBMX (phosphodiesterase inhibitor)‐pretreated glands. S‐0509 (a CCK‐2 receptor antagonist) and atropine had no effect on acid secretion stimulated by wine, ethanol or non‐alcoholic wine in IBMX‐pretreated glands. Famotidine and omeprazole significantly inhibited the acid secretion resulting from all of the above stimulants. BAPTA (an intracellular Ca2+ chelator) inhibited acid secretion stimulated with wine or ethanol in a dose‐dependent manner, but did not inhibit secretion stimulated by non‐alcoholic wine.Conclusions:Wine was found to stimulate gastric acid secretion in gastric glands via two pathways, by an ethanol‐induced increase in the concentration of intracellular Ca2+ in parietal cells, and by histamine release from ECL cells potentially induced by constituents present in wine.
Gastro‐oesophageal reflux disease – pathophysiological issues of clinical relevance
Authors: Penagini R. , Carmagnola S. , Cantu P. 
Published: March 2003

SummaryGastro‐oesophageal reflux disease is a multifactorial disorder in which the pathophysiological mechanisms are variably combined in different patients. Motor dysfunction of the lower oesophageal sphincter (LOS) and, possibly, the proximal stomach is a major cause of the increase in the number of reflux episodes. Transient LOS relaxation is the main mechanism of reflux in many patients with endoscopically negative disease, whereas a hypotensive LOS becomes relevant only in patients with oesophagitis. Alterations in primary and secondary peristalsis contribute to the increased oesophageal acid exposure by delaying clearance. The presence of a hiatus hernia, especially when voluminous and/or non‐reducible, increases the number of reflux episodes by mechanically weakening the oesophago‐gastric junction, and impairs oesophageal clearance. Hypersensitivity to acid is often present and contributes to the clinical manifestations of the disease, whereas oesophageal hypersensitivity, both to chemical and mechanical stimuli, plays a predominant role in a subset of patients. Increased concentrations of noxious compounds in the oesophageal refluxate may contribute to the development of anatomical lesions, but this is still a matter for debate. The clinical relevance of Helicobacter pylori infection and of mucosal defensive factors still needs to be fully elucidated.
Medical treatment of severe ulcerative colitis
Authors: Daperno M. , Sostegni R. , Rocca R. , Rigazio C. , Scaglione N. , Castellino F. , Ercole E. , Pera A. 
Published: March 2003

SummaryApproximately 15% of patients with ulcerative colitis have a severe attack requiring hospitalization at some time during their illness. This treatment leads to a remission in 60–80% of patients and non‐responders may require a total colectomy. Mortality in severe episodes of ulcerative colitis decreased from 31–61% in the 1950s to 5–9% in the 1960s thanks to the introduction of steroids and to a policy of early colectomy. Recently, some new drugs have been shown to be effective in the treatment of severe steroid‐refractory ulcerative colitis. This review concentrates on the clinical evaluation, prognostic factors and new developments in medical therapy in severe ulcerative colitis. A retrospective evaluation of a consecutive series of patients with severe ulcerative colitis admitted to a Gastroenterology Department in Torino, Italy, is also reported.
Maintenance of remission in ulcerative colitis
Authors: Kamm M. A. 
Published: March 2003

SummarySeventy percent of patients with ulcerative colitis can expect to experience a relapse over a 12 month period. Sulfasalazine was the first drug demonstrated to reduce this relapse rate to 21 percent. Subsequent studies have demonstrated that 5‐aminosalicylic acid (5‐ASA) is the main active component, and preparations containing only 5‐ASA have similar efficacy to sulfasalazine. 5‐ASA is readily absorbed from the small intestine; to achieve high a colonic lumenal concentration therefore requires special release formulation. A variety of 5‐ASA preparations is available, differing in their release mechanism, efficacy and side effect profile. Most patients can be maintained in remission using oral 5‐ASA medication. For patients with distal or left sided disease the use of rectal 5‐ASA is also of proven benefit in maintaining remission. Some patients with frequent or severe relapses require stronger immunosuppression, and in these patients azathioprine or 6‐mercaptopurine (6‐MP) are of proven benefit. Azathioprine is also invaluable for maintaining remission in patients who have been treated with cyclosporin for a fulminant acute episode of colitis. The exciting spectre of natural bacterial therapies (probiotics) deserves further exploration.
Interdigestive antroduodenal motility and gastric acid secretion
Authors: Gielkens  , Nieuwenhuizen  , Biemond  , Lamers  , Masclee  
Published: March 2003

Background:In humans, interdigestive acid secretion and antroduodenal motility are closely related with cyclic variations in acid secretion, synchronous with the various phases of the migrating motor complex (MMC). Duodenal acidification inhibits antral motility, but little is known about the effect of acute acid inhibition on antroduodenal motility.Aim:To study the effect of acute acid inhibition on antroduodenal motility.Subjects:Ten healthy volunteers (four men and six women; age range 20–31 years).Methods:Antroduodenal motility (perfusion manometry) and gastric acid secretion (continuous aspiration with recovery marker) were measured simultaneously. Each subject was studied twice in random order during (1) intravenous infusion of saline for one–two complete MMC cycles and (2) during acute acid inhibition with intravenous famotidine (bolus 20 mg, continuous infusion 4 mg/h) for one–two complete MMC cycles or at least 240 min.Results:In the saline study, acid output in phase III (2.1 ± 0.3 mmol/10 min) and late phase II (1.7 ± 0.2 mmol/10 min) was significantly (P < 0.05) increased over early phase II and phase I (1.2 ± 0.2 and 1.2 ± 0.2 mmol/10 min, respectively). Famotidine increased gastric pH to above pH 6 within 30 min. After acid inhibition, duration of MMC cycle during famotidine (106 ± 8 min) was not significantly different from the saline experiment (133 ± 14 min). Phase distribution of the MMC cycle was not significantly different between famotidine (I, II and III: 12 ± 3, 82 ± 3 and 5 ± 1%) and saline (I, II and III: 13 ± 3, 83 ± 3 and 4 ± 1%).Conclusions:Gastric acid secretion varies cyclically with interdigestive antroduodenal motility. Acute acid inhibition with intravenous famotidine does not significantly affect interdigestive antroduodenal motility.
Omeprazole, ranitidine and cimetidine have no effect on peak blood ethanol concentrations, first pass metabolism or area under the time–ethanol curve under ‘real‐life’ drinking conditions
Authors: Brown  , James  
Published: March 2003

Background:Considerable controversy persists over the influence of H2‐receptor antagonists on the first pass clearance of ethanol. The majority of previously published studies have studied the effects of the drugs on low‐dose ethanol in the fasting state. We elected to study the possible interaction under simulated real‐life conditions.Methods:Twenty‐three volunteers were given 0.6 g/kg body weight ethanol in the form of 4.8% beer following a standardized meal. Blood ethanol levels were measured over the next 3 h. Studies were repeated using ethanol administered as an intravenous infusion while subjects consumed the same volume of de‐alcoholized beer. The effects of a minimum of 2 weeks of dosing with cimetidine, ranitidine and omeprazole were examined.Results:Following food, and with ethanol taken in the form of beer, mean first pass metabolism of ethanol was 58% (range 34–78%). No statistically significant difference was found following drug treatment in either percentage first pass metabolism, peak blood ethanol concentration or area under the time–blood ethanol curve.Conclusion:Under these ‘real‐life’ conditions, the concomitant administration of cimetidine, ranitidine or omeprazole is unlikely to have significant physical, social or forensic implications, since they do not significantly change ethanol elimination.
Review article: overview of medical treatments in unresectable hepatocellular carcinoma—an impossible meta‐analysis?
Authors: Mathurin  , Rixe  , Carbonell  , Bernard  , Cluzel  , Bellin  , Khayat  , Opolon  , Poynard  
Published: March 2003

Background:Controversies surrounding medical treatment in patients with unresectable hepatocellular carcinoma continue to persist.Aim:To perform a meta‐analysis of therapeutic modalities which had been evaluated in two or more randomized trials.Methods:Fifty‐two randomized trials were studied; only 30 were included. This overview identified seven therapeutic modalities which had been evaluated in two or more trials: adriamycin, 5‐fluorouracil, interferon, percutaneous ethanol injection, transarterial chemotherapy, the combination of lipiodol with transarterial chemotherapy, and tamoxifen.Results:Comparisons of survival between control groups showed substantial heterogeneity. There was no survival benefit at 1 year with adriamycin (mean difference 4%), 5‐fluorouracil (mean difference −3%), percutaneous ethanol injection (mean difference 6%) or transarterial chemotherapy (mean difference −2%). For interferon, the survival benefit was significant with the Der Simonian & Laird method (mean difference 9%, 95% CI = 1–18%, P = 0.04) but not with the Peto et al. method (2.4 mean odds ratio, 95% CI = O.9–6.8). The meta‐analysis of tamoxifen showed a borderline survival benefit (mean difference 25%, 95% CI = 0–49%, P = 0.05). However, in sensitivity analyses, the survival benefit of tamoxifen was no longer significant.Conclusions:No treatment has clearly proven efficacy in survival. 5‐Fluorouracil, adriamycin and transarterial chemotherapy were not associated with survival benefit at 1 year. The number of randomized controlled trials was insufficient to enable a conclusion to be reached for interferon and percutaneous ethanol injection. Controversy persists concerning tamoxifen efficacy. Interferon and tamoxifen require new randomized controlled trials on a larger population of patients.
Helicobacter pylori eradication as a surrogate marker for the reduction of duodenal ulcer recurrence
Authors: Neil  , Suchower  , Johnson  , Ronca  , Skoglund  
Published: March 2003

Objectives:An abundance of data exists documenting the association of H. pylori eradication with the reduction in duodenal ulcer recurrence.Aim:To evaluate the validity of using H. pylori eradication as a surrogate marker for the reduction in duodenal ulcer recurrence using rigorously controlled studies.Methods:Three controlled clinical trials were conducted in patients with uncomplicated, active duodenal ulcers. Patients were treated with various combinations of omeprazole and amoxycillin. Ulcer healing and H. pylori eradication were assessed. For patients whose duodenal ulcer healed, duodenal ulcer recurrence was determined over a 6‐month period in patients with H. pylori eradication and those remaining positive for H. pylori at least 4 weeks after treatment. To support the data obtained from these clinical trials, a search of the medical literature was conducted to identify additional human clinical trials in which duodenal ulcer recurrence rates were measured and categorized by H. pylori status at least 1 month post‐treatment.Results:In 11 controlled trials, the overall 6–18‐month duodenal ulcer recurrence rate was 54% among patients remaining positive for H. pylori at least 4 weeks after treatment compared to 6% among patients with H. pylori eradication following treatment. This finding was corroborated by the uncontrolled trials, in which the duodenal ulcer recurrence rate was 64% among patients found to be H. pylori‐positive and 6% for patients found to be H. pylori‐negative at least 4 weeks after treatment. A time course of duodenal ulcer recurrence rates using pooled data from both controlled and uncontrolled studies demonstrated that duodenal ulcer recurrence rates for H. pylori‐negative patients persisted for up to 4 years following treatment. Duodenal ulcer recurrence rates for H. pylori‐positive patients increased for the first year, then levelled off. A comparison of the duodenal ulcer recurrence rates for different treatment regimens revealed that eradication regimens based on omeprazole plus antibiotics and bismuth plus antibiotics exhibited similar duodenal ulcer recurrence rates for H. pylori‐positive and ‐negative patients.Conclusion:Regardless of treatment regimens, H. pylori eradication produced a consistent and significant reduction in duodenal ulcer recurrence. Therefore H. pylori eradication, 4 weeks post‐therapy, can be used as a surrogate marker for reduced duodenal ulcer recurrence in investigational clinical trials.