bluuebunny/crossref_metadata_2025 huggingface dataset:
Muscle fibre number is a possible determinant of muscle fibre composition in rats
Authors: Suwa  , Nakamura  , Katsuta
Published: March 2003

The purpose of the present study was to investigate whether the muscle fibre composition is related to the number of muscle fibres. To resolve this issue, we developed fast‐twitch fibre dominant rats (FFDR) by selective breeding and compared the findings to those of control rats (CR) obtained by random breeding. Percentage of type I fibres of the deep portion of gastrocnemius (DG), soleus (SOL), vastus intermedius (VI), adductor longus (AL), and biceps brachii (BB) muscles in FFDR were lower than CR. Percentage of type IIB fibres in DG, VI and AL and percentage of type IIA fibres of SOL in FFDR were higher than CR. However, fibre composition of plantaris (PLAN), extensor digitorum longus (EDL), rectus abdominis (RA), diaphragm (DIA), and palmaris longus (PL) muscles in FFDR were identical with CR. Total fibre numbers on the cross‐sectional area in SOL, PLAN, EDL, AL and PL were counted. Numbers of type I fibres of all those muscles in FFDR were not different from CR. Numbers of type IIA fibres of SOL and AL and of type IIB fibres of AL in FFDR were greater than CR, but there were no significant differences in the number of type IIA or type IIB fibres of PLAN, EDL or PL between the two groups. Based on these observations, it is suggested that there are pleiotropic and muscle‐specific effects on muscle fibre composition. In addition, the number of type II fibres is a possible determinant of muscle fibre composition.
Evidence for an antihypertensive factor from the adrenal medulla of SHR modulating neurogenic vasoconstriction
Authors: Nesterova  , Chuiko  , Sokolova  , Medvedev  , Medvedeva
Published: March 2003

The aim of this study is to investigate some vasoactive properties of the blood of spontaneously hypertensive rats (SHR). Isolated segments of rat tail arteries obtained from normotensive rats (Wistar–Kyoto (WKY) and Wistar) were perfused with blood from conscious donor rats (WKY, Wistar or SHR). Alterations of the neurogenic constrictor responses (NCR) of the isolated segments evoked by electrical stimulation were studied. The amplitude of NCR of the isolated arteries was studied during perfusion with blood according to the perfusion scheme WKY1(1)–SHR1(2)–WKY1(3) and WKY1(1)–WKY2(2)–WKY1(3). The release of 3H‐noradrenaline ([3H]‐NA) from vascular sympathetic fibres was measured. The influence of adrenal demedullation on NCR was estimated. We have shown that NCR of isolated arteries decreased by 28.3 ± 7.9% (P < 0.05 vs. WKY1(1)) during perfusion with blood from SHR (scheme WKY1(1)–SHR1(2)–WKY1(3)). In these experiments, release of [3H]‐NA from sympathetic fibres of the artery segments decreased by 39.9 ± 9.6% during the perfusion with blood from SHR vs. WKY1(1) (P < 0.05). Adrenal demedullation prevented the decrease of NCR during perfusion of the arteries with blood from SHR. In conclusion, the blood of SHR has some antihypertensive factor(s), which causes decrease of NCR in the tail artery from normotensive rats. This decline is accompanied by the decrease of release in [3H]‐NA from the transmural sympathetic fibres and is abolished after adrenal demedullation of blood donor rats.
Gender‐ and thyroid hormone‐related transitions of essential myosin light chain isoform expression in rat soleus muscle during ageing
Authors: Biral  , Ballarin  , Toscano  , Salviati  , Yu  , Larsson  , Betto
Published: March 2003

In this brief review, the modulatory influence of essential myosin light chain (MLC) isoforms on muscle cell contractility is discussed. Specific interest is focused on the expression of the MLC1Sa and MLC1Sb isoforms in the slow‐twitch soleus muscle in male and female rats, during ageing and after thyroid hormone treatment. According to two‐dimensional gel electrophoresis analysis, the MLC1Sa/MLC1SB ratio increased during ageing in both males and females in parallel with the age‐related decrease in shortening velocity reported in muscle fibres expressing the slow (type 1) myosin heavy chain (MHC) isoform. However, the MLC1Sa and MLC1Sb isoform expression responded to thyroid hormone treatment in a complex manner which did not parallel the age‐related changes in shortening velocity reported in hyperthyroid animals. Thus, if MLC1Sa and MLC1Sb isoforms modulate shortening velocity in type 1 fibres, then other modulators of shortening velocity are not regulated by thyroid hormone in co‐ordination with these essential MLCs.
Arterio‐venous differences of blood acid–base status and plasma sodium caused by intense bicycling
Authors: Medbø  , Hanem  , Noddeland  , Jebens
Published: March 2003

After intense exercise muscle may give off hydrogen ions independently of lactate, perhaps by a mechanism involving sodium ions. To examine this possibility further five healthy young men cycled for 2 min to exhaustion. Blood was drawn from catheters in the femoral artery and vein during exercise and at 1‐h intervals after exercise. The blood samples were analysed for pH, blood gases, lactate, haemoglobin, and plasma proteins and electrolytes. Base deficit was calculated directly without using common approximations. The leg blood flow was also measured, thus allowing calculations of the leg’s exchange of metabolites. The arterial blood lactate concentration rose to 14.2 ± 1.0 mmol L–1, the plasma pH fell to 7.18 ± 0.02, and the base deficit rose 22% more than the blood lactate concentration did. The femoral‐venous minus arterial differences peaked at 1.8 ± 0.2 mmol L–1 (lactate), –0.24 ± 0.01 (pH), and 4.5 ± 0.4 mmol L–1 (base deficit), and –2.5 ± 0.7 mmol L–1 (plasma sodium concentration corrected for volume changes). Thus, near the end of the exercise and for the first 10 min of the recovery period the leg gave off more hydrogen ions than lactate ions to the blood, and sodium left plasma in proportion to the extra hydrogen ions appearing. The leg’s integrated excess release of hydrogen ions of 0.88 ± 0.45 mmol kg–1 body mass was 67% of the integrated lactate release. Base deficit calculated by the traditional approximate equations underestimated the true value, but the error was less than 10%. We conclude that intense exercise and lactic acidosis may lead to a muscle release of hydrogen ions independent of lactate release, possibly by a Na+,H+ exchange. Hydrogen ions were largely buffered in the red blood cells.
Factors regulating renal angiotensin‐converting enzyme activity in the rat
Authors: Ye  , Duggan
Published: March 2003

Changes in angiotensin‐converting enzyme (ACE) activity appear to be important in mediating the natriuresis which ensues after administration of an oral or gastric sodium load. In this study, we sought to determine the time course of the changes in ACE activity in the kidney which occur after sodium ingestion. In addition, we sought to investigate mechanisms which might underlie these changes. Angiotensin‐converting enzyme activity was measured by generation of histidyl‐leucine in homogenates of kidneys harvested at varying time‐points after gastric sodium administration. The effects of intravenous sodium loading, solution osmolality and of changes in renal nerve activity were also investigated. Intragastric instillation of both the sodium‐containing solution and its iso‐osmotic urea control solution resulted in significant increases in renal ACE activity (NaCl: P < 0.0005; Urea: P < 0.01). The increase in renal ACE activity after gastric sodium loading was more prolonged than after the urea control (P < 0.025, NaCl vs. urea at 90 min). This prolonged increase in renal ACE activity appeared to reflect a response to absorbed sodium as intravenous sodium administration caused a significant increase in renal ACE activity at 90 min (P < 0.0005). In contrast to these stimuli which increased renal ACE activity, renal denervation caused a significant decrease in ACE activity in the kidney (P < 0.05). We conclude that gastric sodium loading increases renal ACE activity. This effect appears to be due initially to a response to an increase in gastric lumenal osmolality and later to absorbed sodium. These changes in renal ACE activity are not mediated by a decrease in renal nerve activity.
Cardiac natriuretic peptides and continuously monitored atrial pressures during chronic rapid pacing in pigs
Authors: Qi  , Kjekshus  , Klinge  , Kjekshus  , Hall
Published: March 2003

Changes in atrial natriuretic peptide (ANP), N‐terminal proatrial natriuretic peptide and brain natriuretic peptide (BNP) were evaluated in relation to continuously monitored atrial pressures in a pacing model of heart failure. Pigs were subjected to rapid atrial pacing (225 beats min−1) for 3 weeks with adjustments of pacing frequencies if the pigs showed overt signs of cardiac decompensation. Atrial pressures were monitored by a telemetry system with the animals unsedated and freely moving. Left atrial pressure responded stronger and more rapidly to the initiation of pacing and to alterations in the rate of pacing than right atrial pressure. Plasma natriuretic peptide levels were measured by radioimmunoassay and all increased during pacing with BNP exhibiting the largest relative increase (2.9‐fold increase relative to sham pigs). Multiple regression analysis with dummy variables was used to evaluate the relative changes in natriuretic peptides and atrial pressures and the strongest correlation was found between BNP and left atrial pressure with R 2=0.81. Termination of pacing resulted in rapid normalization of ANP values in spite of persistent elevations in atrial pressures. This may reflect an increased metabolism or an attenuated secretory response of ANP to atrial stretch with established heart failure. In conclusion, 3 weeks of rapid pacing induced significant increases in atrial pressures and natriuretic peptide levels. All the natriuretic peptides correlated with atrial pressures with BNP appearing as a more sensitive marker of cardiac filling pressures than ANP and N‐terminal proatrial natriuretic peptide.
Modification of the Xenopus electroretinogram by actions of glycine in the proximal retina
Authors: Arnarsson  , Eysteinsson
Published: March 2003

The electroretinogram (ERG) was recorded from the Xenopus retina, to examine the effects of glycine and strychnine on these responses and to determine the origins of these changes. Glycine at concentrations between 0.1 and 10 m
M reduced the b‐ and d‐waves of the ERG in a dose‐dependent manner, while strychnine increased their amplitude. 2‐Amino‐4‐phosphonobutyric acid (APB) reduced the b‐wave and blocked the effect of glycine, but not strychnine, on the d‐wave. When the d‐wave had first been blocked by kynurenic acid (KYN) or reduced by (+/–)cis‐2,3‐piperidine dicarboxylic acid (PDA) the b‐wave was enhanced by glycine, but not by strychnine. N‐methyl‐
DL‐aspartate (NMDLA), which alters responses in the proximal retina only, blocked the effects of glycine and strychnine on the ERG. This suggests that the glycinergic effects on the ERG are at least partly mediated by processes in the proximal retina. The results further support the suggestion that inhibitory neurotransmitters in the proximal retina may modulate both the b‐ and d‐waves of the Xenopus ERG.
Age‐related differences in twitch contractile properties of plantarflexor muscles in women
Authors: Pääsuke  , Ereline  , Gapeyeva  , Sirkel  , Sander
Published: March 2003

This study compared maximal voluntary isometric strength and electrically evoked twitch characteristics of the plantarflexor muscles among the groups of women of the 3rd (n=14), 4th (n=13), 5th (n=11), 6th (n=12) and 8th (n=13) decade. A significant decrease (P < 0.05–0.001) has been found in isometric maximal voluntary contraction (MVC) force from the 5th decade and in twitch maximal force from the 6th decade. The 3rd decade group produced 72% greater MVC force and 43% greater twitch maximal force than the 8th decade group (P < 0.001). A prolongation (P < 0.01) in twitch contraction time was observed from the 5th decade. Twitch contraction time in the 3rd decade group was 16% shorter (P < 0.001) compared with the 8th decade group (P < 0.01). Twitch half‐relaxation time did not differ significantly (P > 0.05) among the groups. A decrease (P < 0.05–0.001) has been found in twitch maximal rate of force development from the 5th decade and in twitch maximal rate of relaxation from the 6th decade. The 3rd decade group produced 63% greater (P < 0.001) twitch maximal rate of force development than the 8th decade group. It was concluded that in women a marked age‐related reduction in maximal voluntary force‐generating capacity of the plantarflexor muscles and speed of contraction of the electrically evoked twitch takes place after 40 years of age, while reduction in maximal force‐generating capacity and speed of relaxation of the twitch occurs after 50 years of age.
In vivo assessment of villous microcirculation in the rat small intestine in Indomethacin‐induced inflammation: role of mast‐cell stabilizer Ketotifen
Authors: Ruh J. , Vogel F. , Schmidt E.
Published: March 2003

Indomethacin induces an inflammatory reaction in the small intestine in several rat strains. This animal model is widely used to study the implications of intestinal inflammation. Macroscopically, there is evidence that Indomethacin induces a hyperaemic inflammatory reaction in the mucosa, and in our previous studies, we found a significant increase in villous perfusion in the acutely inflamed small intestine. Mast‐cell activation was found to take part in inflammatory reactions in several organ systems in various species. However, no data are available about the effect of mast‐cell degranulation on the perfusion of the mucosa in Indomethacin‐induced intestinal inflammation. Therefore, we used the mast‐cell stabilizer Ketotifen to identify if mast‐cell activation may contribute to changes in the perfusion of single villi in the rat ileum. We found that Ketotifen significantly reduced the Indomethacin induced increased blood flow in the main arteriole 60 min after i.v. application, indicating that mast‐cell degranulation effects microcirculatory disturbances in the mucosa in Indomethacin‐induced intestinal inflammation.
The ‘lactate paradox’, evidence for a transient change in the course of acclimatization to severe hypoxia in lowlanders
Authors: Lundby C. , Saltin B. , Van Hall G.
Published: March 2003

The metabolic response to exercise at high altitude is different from that at sea level, depending on the altitude, the rate of ascent and duration of acclimatization. One apparent metabolic difference that was described in the 1930s is the phenomenon referred to as the ‘lactate paradox’. Acute exposure to hypoxia results in higher blood lactate accumulation at submaximal workloads compared with sea level, but peak blood lactate remain the same. Following continued exposure to hypoxia or altitude, blood lactate accumulation at submaximal work and peak blood lactate levels are paradoxically reduced compared with those at sea level. It has recently been shown, however, that, if the exposure to altitude is sufficiently long, blood lactate responses return to those seen at sea level or during acute hypoxia. Thus, to evaluate the ‘lactate paradox’ phenomenon in relation to time spent at altitude, five Danish lowland climbers were studied at sea level, during acute exposure to hypoxia (10% O2 in N2) and 1, 4 and 6 weeks after arrival in the basecamp of Mt Everest (∼5400 m, Nepal). Basecamp was reached after 10 days of gradual ascent from 2800 m. Peak blood lactate levels were similar at sea level (11.0 ± 0.7 mmol L−1) and during acute hypoxia (9.9 ± 0.3 mmol L−1), but fell significantly after 1 week of acclimatization to 5400 m (5.6 ± 0.5 mmol L−1) as predicted by the ‘lactate paradox’. After 4 weeks of acclimatization, peak lactate accumulation (7.8 ± 1.0 mmol L−1) was still lower compared with acute hypoxia but higher than that seen after 1 week of acclimatization. After 6 weeks of acclimatization, 2 days after return to basecamp after reaching the summit or south summit of Mt Everest, peak lactate levels (10.4 ± 1.1 mmol L−1) were similar to those seen during acute hypoxia. Therefore, these results suggest that the ‘lactate paradox’ is a transient metabolic phenomenon that is reversed during a prolonged period of exposure to severe hypoxia of more than 6 weeks.
Relationship between muscle fibre composition, glucose transporter protein 4 and exercise training: possible consequences in non‐insulin‐dependent diabetes mellitus
Authors: Daugaard J. R. , Richter E. A.
Published: March 2003

Skeletal muscle is composed of different fibre types, which differ in contractile as well as in metabolic properties. The myosin molecule, which exists in several different isoforms, is of major importance in determining the contractile properties of the muscle cell. The plasticity of skeletal muscle is reflected in this tissue’s adaptability to changes in the functional demand. In both rats and humans, a decrease in activity level will in most cases change the muscle fibre composition towards faster myosin isoforms and an increase in activity level (such as seen with exercise training) will induce an increase in slower myosin isoforms. The glucose transporter protein 4 (GLUT4), which is the major insulin regulatable glucose transporter in mammalian skeletal muscle, is found in larger amounts in slow muscle fibres compared with fast muscle fibres. An increase in activity level will increase the GLUT4 protein expression and a decrease in activity level will in most cases decrease GLUT4. Thus, there seems to be some kind of relationship between the muscle fibre type and GLUT4. However, the main factor regulating both the GLUT4 protein expression and the muscle fibre composition seems to be the activity level of the muscle fibre. Patients suffering from non‐insulin‐dependent diabetes mellitus (NIDDM) are insulin resistant in their skeletal muscles but are generally normal when it comes to skeletal muscle fibre composition and the GLUT4 protein expression. There is good evidence that exercise training beneficially impacts on insulin sensitivity in healthy individuals and in patients with type II diabetes. An increase in the GLUT4 protein expression in skeletal muscle may at least partly explain this effect of training.
Diffusion‐limited tissue equilibration and arteriovenous diffusion shunt describe skeletal muscle nitrous oxide kinetics at high and low blood flows in sheep
Authors: Doolette D. J. , Upton R. N. , Zheng D.
Published: March 2003

This study evaluated the relative importance of perfusion and diffusion mechanisms in compartmental models of blood : tissue inert gas exchange in skeletal muscle. Nitrous oxide kinetics in a hind limb skeletal muscle bed were determined during and after 20 min of nitrous oxide inhalation, at separate low and high steady states of hind limb blood flow in five sheep under halothane anaesthesia. Nitrous oxide concentrations in arterial and femoral vein blood were determined using gas chromatographic analysis and femoral vein blood flow was monitored continuously. Parameters and model selection criteria of various perfusion‐ or diffusion‐limited structural models of skeletal muscle were estimated by simultaneous fitting of the models to the mean observed femoral vein nitrous oxide concentration for both blood flow states. Purely perfusion‐limited models fit the data poorly. Models that allowed a diffusion‐limited exchange of nitrous oxide between a perfusion‐limited tissue compartment and an unperfused deep compartment provided better overall fit of the data and credible parameter estimates. The data was best described by allowing, in addition to diffusion‐limited tissue equilibration, counter current diffusion of nitrous oxide between arterial and venous blood. The level of tissue blood flow modifies the magnitudes of both these diffusion effects. These results suggest a dual role of diffusion in blood : tissue inert gas equilibration in skeletal muscle.
The effect of hypoxia on shortening contractions in rat diaphragm muscle
Authors: Machiels H. A. , Van Der Heijden H. F. M. , Heunks L. M. A. , Dekhuijzen P. N. R.
Published: March 2003

Hypoxia is known to reduce isometric contractile properties of isolated rat diaphragm bundles. Its effect on isotonic contractile properties (i.e. force–velocity relationship and power output) has not been studied. We hypothesized that hypoxia reduces velocity of shortening and consequently power output of the unfatigued muscle, and shortens endurance time during isotonic contractions. Force–velocity relationship, power output, and fatigue resistance of rat diaphragm muscle bundles were measured during hypoxia (PO2: 6.6 ± 0.2 kPa) and compared with hyperoxia (PO2: 91.8 ± 0.7 kPa). Force was clamped from 1 to 100% of maximal tetanic force (Po). Fatigue during isotonic contractions was induced by repeated stimulation every 2 s at a clamp level of 33% of Po. Hypoxia did not affect isometric force generation compared with hyperoxia, nor contraction or relaxation time. In contrast, maximum shortening velocity decreased significantly (hypoxia: 4.2 ± 0.3, hyperoxia: 6.0 ± 0.2 Lo/s, P < 0.05). The force–velocity curve shifted downwards (P < 0.05). Hypoxia lowered power output at each load compared with hyperoxia (P < 0.05). The isotonic endurance time was shorter during hypoxia compared with hyperoxia (80 ± 2 vs. 130 ± 3 s, P < 0.05). These data show that hypoxia depresses isotonic contractile properties and power output, and reduces endurance time during repeated isotonic contractions.
Modifications of microvascular filtration capacity in human limbs by training and electrical stimulation
Authors: Brown M. D. , Jeal S. , Bryant J. , Gamble J.
Published: March 2003

This study investigated whether an increase in microvascular surface area as a result of endurance training, which increases human skeletal muscle capillarity, would translate to greater capacity for fluid filtration compared with strength training, which does not affect capillary supply. Values for filtration capacity, Kf, derived from the slope of calf volume change, Jv, measured by venous occlusion plethysmography, against cuff pressure during a protocol of small cumulative pressure steps, were significantly higher in endurance athletes (5.78 ± 0.88 mL min–1 100 mL–1 mmHg–1 × 10–3, P < 0.05) than controls (3.38 ± 0.32 mL min–1 100 mL–1 mmHg–1 × 10–3) whereas strength‐trained athletes had values similar to control (4.08 ± 0.56 mL min–1 100 mL–1 mmHg–1 × 10–3, ns), suggesting that surface area is important. However, when sedentary subjects underwent either a 4‐week unilateral dynamic plantarflexion training programme (70% peak power, 20 min day–1, 5 days week–1) or a calf muscle electrical stimulation programme (8 Hz, 3 × 20 min day–1, 5 days week–1), neither of which caused limb blood flow to alter after training nor would be expected to increase capillarity, only the stimulation group showed a significant increase in Kf (6.68 ± 0.62 mL min–1 100 mL–1 mmHg–1 × 10–3 post‐training vs. 3.38 ± 0.38 pre‐training, P < 0.05). This may be because stimulation enhances perfusion preferentially to glycolytic fibres, or maintains high levels of vascular endothelial growth factor (VEGF) or changes lymph clearance.
Central and peripheral cardiovascular adaptations to exercise in endurance‐trained children
Authors: NOTTIN S. , VINET A. , STECKEN F. , N'GUYEN L.‐D. , OUNISSI F. , LECOQ A.‐M. , OBERT P.
Published: March 2003

Stroke volume (SV) response to exercise depends on changes in cardiac filling, intrinsic myocardial contractility and left ventricular afterload. The aim of the present study was to identify whether these variables are influenced by endurance training in pre‐pubertal children during a maximal cycle test. SV, cardiac output (Doppler echocardiography), left ventricular dimensions (time–movement echocardiography) as well as arterial pressure and systemic vascular resistances were assessed in 10 child cyclists (VO2max: 58.5 ± 4.4 mL min−1 kg−1) and 13 untrained children (UTC) (VO2max: 45.9 ± 6.7 mL min−1 kg−1). All variables were measured at the end of the resting period, during the final minute of each workload and during the last minute of the progressive maximal aerobic test. At rest and during exercise, stroke index was significantly higher in the child cyclists than in UTC. However, the SV patterns were strictly similar for both groups. Moreover, the patterns of diastolic and systolic left ventricular dimensions, and the pattern of systemic vascular resistance of the child cyclists mimicked those of the UTC. SV patterns, as well as their underlying mechanisms, were not altered by endurance training in children. This result implied that the higher maximal SV obtained in child cyclists depended on factors influencing resting SV, such as cardiac hypertrophy, augmented myocardium relaxation properties or expanded blood volume.
Surgical manipulation, but not moderate exercise, is associated with increased cytokine mRNA expression in the rat soleus muscle
Authors: SchiØtz Thorud H.‐M. , WislØff U. , Lunde P. K. , Christensen G. , Ellingsen Ø. ,   O. M., Sejersted
Published: March 2003

Interleukin (IL)‐6 production in contracting skeletal muscle and IL‐6 concentration in plasma are increased after prolonged and strenuous exercise. However, as tissue stress or damage are unspecific triggers of increased cytokine levels, we examined whether moderate muscle activity is an independent stimulus for cytokine expression, and to which extent invasive procedures might affectthe results. Soleus muscles were isolated from sedentary rats or from rats that had been running on a treadmill at moderate intensity (70% of maximal oxygen uptake) for 1 h. In another group the soleus muscle was prepared in situ and stimulated intermittently at 5 Hz for 1 h, so that maximal developed force declined by 30%. In situ prepared soleus muscles not subjected to electrical stimulation were used as controls. Messenger RNA (mRNA) expression of 11 cytokines was analysed in the soleus muscles using multiprobe RNAse protection assay, and IL‐6 plasma concentration was measured by enzyme‐linked immunosorbent assay. Treadmill exercise did not affect the mRNA expression of any of the measured cytokines in the soleus muscle. Irrespective of electrical stimulation, mRNA expression of IL‐6 and IL‐1β were significantly increased in the surgically manipulated soleus muscles. Interleukin‐6 plasma concentration was not affected by treadmill running or electrical stimulation. Conclusion, gentle surgical manipulation is a strong stimulus for IL‐6 and IL‐1β mRNA synthesis in skeletal muscle, whereas exercise or electrical muscle stimulation at moderate intensity does not independently affect cytokine mRNA levels in the contracting soleus.
Cortical blood flow autoregulation revisited using laser Doppler perfusion imaging
Authors: Kimme P. , Ledin T. , Sjöberg F.
Published: March 2003

Methods of laser Doppler perfusion monitoring (LDPM) and imaging (LDPI) have been validated and found useful for measurements of brain blood flow in several studies. The present work was undertaken to examine the cortical blood flow autoregulatory phenomenon as it has lately been questioned and claimed to be method‐dependent and related to sample volume. Spatial variations in cerebral cortical blood flow (CBFcortex) in the pressure range 20–140 mmHg (static cerebral autoregulation; caval block/angiotensin infusion) were studied in six mechanically ventilated (hypocapnic, normocapnic and hypercapnic) pigs anaesthetized with propofol and fentanyl. Although the cortical blood flow values sampled were highly heterogeneously distributed, they were strongly pressure‐dependent as well as CO2‐dependent (P < 0.001). A cumulative cerebral blood flow (CBF)–pressure (MAP) plot comprising all values obtained indicated a pressure range between 70 and 120 mmHg where CBF remained almost constant. However, at the local level in the cortex (mm2) the same type of ‘classic’ autoregulatory flow : pressure graphs (FPG) were found in only a few of the cases of the cortical areas examined (n = 96). Alterations in blood PaCO2 saturation did not affect the pressure : flow relationship at low perfusion pressures, whereas at normal or above normal values, and as anticipated, hypercapnia considerably increased CBF (P < 0.001). ‘Classic’ autoregulatory FPGs were found only when all values sampled were clustered together, whereas, as a new finding, data are presented indicating that autoregulatory capacity is lacking at the local level at some cortical surface areas.
Assessment of veld conditions with multivariate techniques in mixed bushveld, South Africa
Authors: DÖrgeloh W. G.
Published: March 2003

The species composition of the herbaceous layer was surveyed in eight plant communities with a small‐quadrat method. Ordination techniques were applied to these data to identify relative homogenous grazing areas, assess the veld condition of each unit and to identify indicator species, based on a grazing gradient. Five relative homogenous grazing areas were identified and should be treated as such for management purposes. The veld in the Nylsvlei Nature Reserve was generally in a good condition due to the low stocking densities of game (≈0.29 animals ha−1) which have been maintained for many years. Nine indicator species, i.e. Cynodon dactylon, Digitaria eriantha, Ischaemum afrum, Leersia hexandra, Oryza longistaminata, Setaria sphacelata, Sporobolus ioclados, Sporobolus pyramidalis, and forbs, were identified which may be used for future monitoring of veld condition in the different vegetation units.
Seasonal changes of impala (Aepyceros melampus, Lichtenstein, 1812) faecal helminth egg counts through a one‐year period
Authors: Ocaido M. , Siefert L. , Baranga J.
Published: March 2003

The study was done in Lake Mburo area, Uganda, consisting of Lake Mburo National Park and surrounding ranches. The study involved monitoring changes of output of helminth eggs per gram (e.p.g.) by impala for 12 months. Fresh faecal samples, 178 in total, were collected from the rangeland and subjected to floatation and culture tests. There was a peak faecal e.p.g. output from March to April and from October to November. This period coincided with time of high rainfall and calving peak of impala. There was no faecal e.p.g. observed during the dry spell from June to July.
Activity patterns and feeding behaviour of the tree hyrax, Dendrohyrax arboreus, in the Parc National des Volcans, Rwanda
Authors: Milner Jos M. , Harris Stephen
Published: March 2003

Activity patterns of Dendrohyrax arboreus were investigated by direct observation of a habituated population in the Parc National des Volcans, Rwanda. Of seventeen animals caught, four were males and thirteen were females. Of the population, 17% were juveniles. Population estimates from transects indicated a biomass of 23.3 kg/ha. Radio‐tracking of ten individuals showed bimodal activity patterns, with peaks after dusk and later in the night for males and during the day in females. Hyrax were active 16% of the time. Feeding was the dominant activity and mature leaves of Hagenia abyssinica were the most important food. Travelling within and between trees occupied 4% of the time and occurred predominantly during daylight hours. Calling behaviour was markedly seasonal, being most pronounced in the dry season when hyrax called regularly in the early evening, and often a second time late at night. During the rains, calls were infrequent and unpredictable, tending to occur in the second half of the night. There was no correlation between weather or lunar conditions and calling behaviour. The ecological strategy of tree hyrax in terms of metabolic rate, thermoregulation and energy conservation is discussed in the light of their activity and feeding behaviour.
Comparison of sample and total counts of elephant and buffalo in Masai Mara, Kenya
Authors: Ottichilo Wilber K.
Published: March 2003

Both aerial transect sample counts and total counts of elephant and buffalo were conducted in the study area during the wet season. The results from the two counting methods were tested for significant difference. The test showed that the results were not significantly different for both the elephant (P > 0.05) and buffalo (P > 0.05).
The effects of woodfuel consumption in the ASAL areas of kenya: the case of marsabit forest
Authors: Kirubi C. , Wamicha W. N. , Laichena J. K.
Published: March 2003

In the arid and semiarid lands (ASAL) of Kenya, fuelwood and charcoal constitute 95–98% of the total energy demand for cooking, heating and lighting. The resultant deleterious ecological effects are severe and need urgent remedial interventions. A study was carried out in Marsabit District, which is a vast ASAL region, to examine the effects of woodfuel consumption on Marsabit Forest and the surrounding areas. It was found that wood for fuel harvested from Marsabit Forest was approximately 56,000 tons y−1. The rate of deforestation was estimated at 1.6 ha y−1. This resulted in great loss of indigenous biodiversity, destruction of vital ecosystems and habitats. To control further degradation of the forest, it is recommended that an immediate ban be imposed to stop harvesting of the indigenous species such as Olea spp. and Teclea spp., which are seriously endangered. Also, woodfuel conservation through wider and more efficient use of the improved energy‐saving technologies should be enhanced.
Factors influencing the distribution of the mole rat, Cryptomys zechi (Rodentia, Bathyergidae) in Ghana
Authors: Yeboah S. , Akyeampong S.
Published: March 2003

Factors influencing the distribution of the Ghana mole rat Cryptomys zechi were investigated in a small part of the middle Volta basin of Ghana where it is endemic. Soil type appeared to be the most important factor controlling mole rat distribution in the area; the mole rats preferred areas where the soil was silt loam. In areas where mole rats were found, local distribution was influenced by food availability and land preparation methods for farming. The highest concentrations of mole rat colonies were found in farmlands where traditional hoe ploughing is used for land preparation and where plants with underground storage organs were more diverse; the lowest concentration was in farms where mechanized ploughing is used for land preparation.
Proton pump inhibitor modifies inflammatory reaction in human gastric mucosa infected by Helicobacter pylori
Authors: Suzuki M. , Suzuki H. , Kitahora T. , Miyazawa M. , Nagahashi S. , Suzuki K. , Ishii H.
Published: March 2003

Aim:

To examine whether proton pump inhibitors modify the production of oxygen‐derived free radicals and related cytokines in the human gastric mucosa infected with H. pylori.

Methods:

Thirty‐four H. pylori‐positive peptic ulcer patients (23 gastric ulcer, 11 duodenal ulcer) were enrolled. Biopsy tissue samples were obtained endoscopically from the antrum and corpus. Tissue content of neutrophil myeloperoxidase (myeloperoxidase) and IL‐8 was measured by ELISA. Mucosal production of oxygen‐derived free radical was measured using luminol‐dependent chemiluminescence (ChL). A proton pump inhibitor (either lansoprazole 30 mg, omeprazole 20 mg, or rabeprazole 10 mg) was administered daily by mouth to all patients for 8 weeks. Endoscopic examination was then repeated, and biochemical analysis was performed.

Results:

Antral myeloperoxidase decreased significantly after proton pump inhibitor treatment (5.23 ± 7.00–2.76 ± 5.11 ng/mg, P < 0.02), but corpus myeloperoxidase was unchanged. IL‐8 was also modified by proton pump inhibitors and these changes were parallel to those of myeloperoxidase. Corpus ChL was significantly increased from 88.5 ± 69.8–159 ± 172 counts/10 s/mg after proton pump inhibitor treatment, whereas antrum ChL was not altered. H. pylori infection rate was decreased in the antrum as well as the corpus.

Conclusions:

Proton pump inhibitor treatment stimulated oxygen‐derived free radical production in the corpus mucosa.
Conditional loss of TGF‐β signalling leads to increased susceptibility to gastrointestinal carcinogenesis in mice
Authors: Hahm K‐B. , Lee K. M. , Kim Y. B. , Hong W. S. , Lee W. H. , Han S. U. , Kim M. W. , Ahn B. O. , Oh T. Y. , Lee M. H. , Green J. , Kim S. J.
Published: March 2003

Background:

Downregulation of TGF‐β receptors is implicated in colon cancer development. Inactivation of either of the two transmembrane serine/threonine kinases, TGF‐β1 types I/II receptors, is now implicated in carcinogenesis, especially gastrointestinal carcinogenesis.

Methods:

We generated transgenic mice, called pS2–dnRII or ITF–dnRII, of which the dominant negative mutant of the TGF‐β type II receptor was expressed under the control of tissue‐specific promoters, the pS2 promoter for stomach and ITF for intestine. They were either infected with H.pylori (ATCC 43504 strain, CagA+ and VacA+) or administered with azoxymethane to determine the significance of loss of TGF‐β signalling in gastrointestinal carcinogenesis.

Results:

Gastric adenocarcinoma developed in pS2–dnRII mice, whereas only chronic active gastritis was noted in wild‐type littermates after 36 weeks of H.pylori infection. Mice lacking in TGF‐β signalling specifically in the stomach showed a significantly higher proliferation cell nuclear antigen‐labelling index when infected with H.pylori than wild‐type littermates (P < 0.01). Development of colonic aberrant crypt foci was provoked in mice by intraperitoneal injections of azoxymethane, and ITF–dnRII mice showed significantly higher incidences of ACF and colon cancers than wild‐type littermates.

Conclusions:

Maintaining normal TGF‐β signalling in the gastrointestinal tract seems to be important either for preventing abnormal mucosal proliferation, or for suppressing or retarding carcinogenesis.
The relationship between gastric cancer cells circulating in the blood and microsatellite instability positive gastric carcinomas
Authors: Czopek J. , Bialas M. , Rudzki Z. , Zazula M. , Pituch‐Noworolska A. , Zembala M. , Popiela T. , Kulig J. , Kolodziejczyk P. , Stachura J.
Published: March 2003

Background:

Cancers characterized by microsatellite instability may be biologically different from their counterparts with stable microsatellite sequences. Circulating cancers cell present in blood prior to surgery may constitute an adverse prognostic finding.

Aim:

To correlate these two phenomena with morphological features and survival in advanced gastric cancer.

Methods:

We examined 76 cases of resected sporadic, advanced gastric cancer by means of routine morphology and a panel of microsatellite markers. Sixty‐six cases were screened for presence of cancer cells circulating in blood prior to the surgery using combined morphological and immunocytochemical approach.

Results:

Twenty‐one (27.6%) cases demonstrated microsatellite instability in at least one locus. Among them 11 (14.5%) showed microsatellite instability in more than 30% (4/12) examined loci, and they were therefore designated as replication error positive (RER+). Circulating cancer cells were detected in 2/19 microsatellite instability and in 11/47 remaining cases (difference not significant). The survival of the microsatellite instability cases was significantly better. The presence of circulating cancer cells did not correlate with survival.

Conclusion:

It is possible that the microsatellite instability status, but not circulating cancer cells, constitutes a prognostic predictive factor in advanced gastric carcinoma. Confirmation of this hypothesis requires continuation of patient follow‐up.
Review article: albumin for circulatory support in patients with cirrhosis
Authors: Ginès P. , Guevara M. , De Las Heras D. , Arroyo V.
Published: March 2003

Renal function abnormalities and ascites in cirrhosis are the final consequence of a circulatory dysfunction characterized by marked splanchnic arterial vasodilation. This causes a reduction in effective arterial blood volume and the homoeostatic activation of vasoconstrictor and sodium‐retaining systems. Albumin is very effective in preventing renal failure associated with large‐volume paracentesis and spontaneous bacterial peritonitis, conditions that are known to cause an impairment of circulatory function in patients with cirrhosis and ascites. Moreover, albumin administration improves survival in patients with spontaneous bacterial peritonitis. In patients with hepatorenal syndrome the administration of vasoconstrictor drugs in combination with albumin improves circulatory and renal function markedly and survival slightly. By contrast, the administration of albumin without vasoconstrictors has marginal or no effects on renal function in this setting.
Review article: the Molecular Adsorbents Recirculating System (MARS) in liver failure
Authors: Sen S. , Mookerjee R. P. , Davies N. A , Williams R. , Jalan R.
Published: March 2003

In recent years different artificial liver support systems are being developed for use in patients with acute decompensation of chronic liver disease or acute liver failure. The molecular adsorbents recirculating system (MARS), a device in which patient's blood is dialysed across an albumin‐impregnated membrane against a recirculated albumin‐containing solution, seems to be effective in removing albumin‐bound toxins, such as fatty acids, bile acids and bilirubin. Although the clinical experience with MARS is scarce, some pilot studies have reported its effectiveness at improving liver function and hepatic encephalopathy in patients with acute decompensation of chronic liver disease, and renal function in patients with hepatorenal syndrome type I. Data regarding MARS experience in acute liver failure and in primary graft dysfunction are encouraging but limited. Its real usefulness in these settings is, at present, under evaluation in randomized controlled clinical trials.
Review article: initial therapy of reflux disease with esomeprazole
Authors: Dent J.
Published: March 2003

Large clinical trials in patients with reflux oesophagitis have shown esomeprazole, 40 mg once daily, to be convincingly superior in the healing of oesophagitis when compared with both omeprazole, 20 mg once daily, and lansoprazole, 30 mg once daily. The greatest advantage for esomeprazole is with healing of the more severe grades of oesophagitis. Esomeprazole, 40 mg once daily, has also been shown to be significantly superior in the treatment of heartburn. Studies in endoscopy‐negative patients, or in both oesophagitis and endoscopy‐negative patients, have demonstrated good efficacy for esomeprazole, with high levels of symptom control achieved in the first 7 days of therapy.
Clinical economics review: functional (non‐ulcer) dyspepsia
Authors: Tebaldi  , Heading
Published: March 2003

Dyspepsia is common within the general population and it imposes a significant burden on health‐care resources. Calculation of the economic implications of functional dyspepsia is constrained by the fact that it is only possible to make this diagnosis in a minority of individuals with the disorder, because many do not seek medical attention and investigation is not appropriate for all who do. Studies which attempt to assess the effectiveness or cost‐effectiveness of therapy may be further constrained by the fact that there is now good evidence that many patients with dyspepsia seek medical attention not so much because of the severity of symptoms, but because they fear that the symptoms signal the presence of some serious underlying disease. In this situation, effective well‐founded reassurance that no serious disease is present is an important outcome of medical intervention and one which should be included in an economic appraisal of dyspepsia management.

For obvious reasons, it is sensible to compare the cost‐effectiveness of various clinical management strategies applicable in dyspepsia. Decision‐tree analyses are currently fashionable but suffer from the major defect that there is no theoretical basis from which patient satisfaction with treatment options can be assessed. It is suggested that for disorders such as functional dyspepsia, which are non‐lethal and non‐progressive, recommendations about acceptable clinical manage‐ ment strategies require that account be taken of patient satisfaction with the strategies being reviewed. Cost‐effectiveness calculations which take no account of this aspect of outcome are of limited relevance to clinical practice.
The effect of mosapride, a novel prokinetic, on acid reflux variables in patients with gastro‐oesophageal reflux disease
Authors: Ruth  , Hamelin  , Röhss  , Lundell
Published: March 2003

Background:

Mosapride is a novel prokinetic agent facilitating acetylcholine release from the enteric cholinergic neurones through a selective 5‐HT4 receptor agonistic action. It is also active through its main metabolite M1, which is a 5‐HT3 antagonist. The importance of motor dysfunction in the pathogenesis of gastro‐oesophageal reflux disease (GERD) makes it interesting to examine the effect of mosapride on oesophageal acid exposure.

Methods:

The effect of mosapride on oesophageal 24‐h acid reflux variables was studied in 21 patients with GERD symptoms and a pre‐entry total acid exposure time (pH < 4) of more than 5%. Ambulatory pH monitoring was performed after treatment with 40 mg mosapride citrate or placebo q.d.s. for 2 days in random order, using a double‐blind crossover technique, with a washout period of at least 5 days.

Results:

Mosapride was significantly more effective than placebo in decreasing the total number of reflux episodes, the total number of reflux episodes lasting more than 5 min and the total time, as well as the amount of day time, of intra‐oesophageal pH below 4. Consequently, mosapride also significantly improved total acid clearance time.

Conclusion:

Mosapride 40 mg q.d.s. is effective in decreasing acid reflux in the oesophagus in patients with GERD and therefore has the potential to be effective in the treatment of this disease.
Ranitidine bismuth citrate versus omeprazole triple therapy for the eradication of Helicobacter pylori and healing of duodenal ulcer
Authors: Catalano  , Catanzaro  , Bentivegna  , Brogna  , Condorelli  , Cipolla
Published: March 2003

Aim:

To compare the efficacy and safety of triple therapy with omeprazole plus amoxycillin and clarithromycin vs. ranitidine bismuth citrate plus amoxycillin and clarithromycin in the treatment of Helicobacter pylori‐associated duodenal ulcers.

Methods:

Eighty‐one patients with duodenal ulcers were randomized to the following treatments: 39 cases with amoxycillin 1 g b.d. and clarithromycin 500 mg b.d. for 1 week plus omeprazole 20 mg b.d. for 2 weeks (omeprazole + amoxycillin + clarithromycin (OAC)), and 42 cases to the same regimen of amoxycillin and clarithromycin for 7 days plus ranitidine bismuth citrate 400 mg b.d. for 2 weeks (ranitidine bismuth citrate + amoxycillin + clarithromycin (RbAC)). Upper gastrointestinal endoscopy was performed together with a rapid urease test and histological examination of antral and corpus biopsy samples prior to treatment and 4 weeks after the end of therapy.

Results:

Thirty‐four patients in the OAC group and 38 in the RbAC group completed the treatment and 4‐week follow‐up. H. pylori was eradicated in 30 of 34 patients (88%) in the OAC group and in 32 of 38 patients (84%) in the RbAC group according to a per‐protocol analysis (P = N.S.). Thirty‐three (97%) patients treated with OAC and 36 (95%) treated with RbAC presented healed duodenal ulcers at 4 weeks (P = N.S.). On an intention‐to‐treat basis there was no difference in H. pylori eradication between the OAC (77%) and RbAC groups (76%); duodenal ulcer healing was achieved in 85 and 86% of patients in the OAC and RbAC groups, re‐ spectively (P = N.S.).

Conclusion:

The OAC and RbAC triple therapy regimens proved equally effective in both H. pylori eradication and in duodenal ulcer healing.