bluuebunny/crossref_metadata_2025 huggingface dataset:
Differentiation of the peptidergic vasoregulatory response to standardized splanchnic hypoperfusion by acute hypovolaemia or sepsis in anaesthetized pigs
Authors: Åneman A. , Bengtsson J. , Snygg J. , Holm M. , Pettersson A. , Fändriks L.
Published: March 2003

This study was performed to integratively investigate the vasoregulatory response during standardized splanchnic hypoperfusion in pigs. Splanchnic perfusion was reduced to 50% of baseline by: haemorrhage by 20 and 40% of the estimated total blood volume; femoral venous infusion of live E. coli to establish sepsis of systemic origin; portal venous infusion of live E. coli to establish sepsis of splanchnic origin. Invasive haemodynamic monitoring and radioimmunoassay analyses of arterial plasma concentrations of angiotensin II, endothelin‐1 and atrial natriuretic peptide were carried out. Acute hypovolaemia reduced systemic and splanchnic vascular resistances following transient increases and increased angiotensin II levels (+587%), whereas endothelin‐1 and atrial natriuretic peptide levels did not change significantly. Systemic sepsis following femoral venous infusion of E. coli resulted in increased splanchnic vascular resistance and increased levels of angiotensin II (+274%), endothelin‐1 (+134%) and atrial natriuretic peptide (+185%). Infusion of E. coli via the portal venous route induced an increase in splanchnic vascular resistance associated with particularly elevated levels of angiotensin II (+1770%) as well as increased endothelin‐1 (+201%) and atrial natriuretic peptide (+229%) concentrations. Hypovolaemia and sepsis, although standardized with a predefined level of splanchnic hypoperfusion, elicited differentiated cardiovascular and vasopeptidergic responses. Sepsis, particularly of portal origin, notably increased splanchnic vascular resistance related to increased production of the vasoconstrictors angiotensin II and endothelin‐1. The role of atrial natriuretic peptide as a vasodilator seems to be of subordinate importance in hypovolaemia and sepsis.
Regulation of macrophage nitric oxide synthesis by endothelial cells: a role for NG,NG‐dimethylarginine
Authors: Fickling  , Holden  , Cartwright  , Nussey  , Vallance  , Whitley
Published: March 2003

NG,NG‐dimethylarginine is an endogenous inhibitor of nitric oxide synthesis produced by endothelial cells and found in the plasma and urine of normal adults. We have examined the ability of NG,NG‐dimethylarginine, produced by endothelial cells (SGHEC‐7), to regulate the production of nitric oxide by lipopolysaccharide‐stimulated mouse macrophage cells (J774.2). Stimulation of SGHEC‐7 or J774.2 cells with lipopolysaccharide had no effect on their release of NG,NG‐dimethylarginine into the culture supernatant. Stimulation of J774.2 cells with lipopolysaccharide for 24 h significantly stimulated nitric oxide production by J774.2 but not SGHEC‐7 cells. When lipopolysaccharide‐stimulated J774.2 cells were co‐cultured with endothelial cells for 24 h, there was a significant inhibition of nitrite accumulation. The inhibition observed was dependent on the endothelial cell number (12 ± 5% [mean ± SEM] following incubation with 0.6 × 105 cells, up to 47 ± 8% with 4.8 × 105 cells). The inhibitory effect of endothelial cells was prevented by incubation with increasing concentrations of
L‐arginine; the IC50 was 2.9 ± 0.6 m
M arginine. Western blot analysis indicated that the expression of inducible nitric oxide synthase was not inhibited by co‐culture with SGHEC‐7 cells. The results presented here demonstrate that NG,NG‐dimethylarginine synthesized by endothelial cells may inhibit nitric oxide synthase in adjacent cells and play a role in the regulation of nitric oxide synthesis by macrophages.
Near‐infrared spectroscopy for monitoring muscle oxygenation
Authors: Boushel R. , Piantadosi C.A.
Published: March 2003

Near‐infrared spectroscopy (NIRS) is a non‐invasive method for monitoring oxygen availability and utilization by the tissues. In intact skeletal muscle, NIRS allows semi‐quantitative measurements of haemoglobin plus myoglobin oxygenation (tissue O2stores) and the haemoglobin volume. Specialized algorithms allow assessment of the oxidation–reduction (redox) state of the copper moiety (CuA) of mitochondrial cytochrome c oxidase and, with the use of specific tracers, accurate assessment of regional blood flow. NIRS has demonstrated utility for monitoring changes in muscle oxygenation and blood flow during submaximal and maximal exercise and under pathophysiological conditions including cardiovascular disease and sepsis. During work, the extent to which skeletal muscles deoxygenate varies according to the type of muscle, type of exercise and blood flow response. In some instances, a strong concordance is demonstrated between the fall in O2stores with incremental work and a decrease in CuA oxidation state. Under some pathological conditions, however, the changes in O2stores and redox state may diverge substantially.
Relationships between muscle morphology and insulin sensitivity are improved after adjustment for intra‐individual variability in 70‐year‐old men
Authors: Hedman  , Berglund  , EssÉn‐Gustavsson  , Reneland  , Lithell
Published: March 2003

The purpose of this investigation was to examine to what extent variability in the muscle morphology and insulin sensitivity influence the correlation between them. Reproducibility of muscle characteristics was estimated in duplicate biopsies from the same thigh of 23 subjects from a cohort of 70‐year‐old men. The coefficient of variation (CV) for different characteristics of muscle morphology was between 11 and 42% in duplicate biopsies. Coefficient of variation for markers of insulin sensitivity ranged between 12 and 39%. The variability reflected by intra‐class correlation ranged from 0.23 to 0.60 for muscle morphology and from 0.68 to 0.96 for estimates of insulin sensitivity. The correlation analysis between muscle morphology and insulin resistance was performed in a sample of 515 men from the cohort, correlation coefficients were calculated with (rtrue) and without (r) adjustment for intra‐individual variation. Insulin sensitivity showed a positive relationship with percentage of type I fibres (rtrue=0.33, r=0.21; P < 0.0001) and capillary density (rtrue=0.43, r=0.21; P < 0.0001) and negative correlations with percentage of type IIB fibres (rtrue=–0.35, r=–0.24; P < 0.0001). Capillary density was inversely correlated to insulin. Thus, an obvious improvement of the correlation was seen after correcting intra‐individual variation. In conclusion, owing to the low degree of reproducibility of muscle morphology variables and insulin sensitivity, implying a noticeable underestimation of correlations, the r‐values should be adjusted for within‐subject variation in order to demonstrate a more accurate estimate of the strength of the relationships studied.
Force deficits after repeated stretches of activated skeletal muscles in female and male rats
Authors: Willems M. E. T. , Stauber W. T.
Published: March 2003

Force deficits after stretches of activated plantar flexor muscles were measured in six male Sprague–Dawley rats (285 ± 10 g, age 62 ± 4 days, mean ± SE) and compared with six age‐matched (193 ± 6 g, age 67 ± 3 days) and six weight‐matched female rats (273 ± 7 g, age 141 ± 9 days). Twenty stretches, imposed on isometric contractions at 90° (0.2 ms pulse duration, 80 Hz, 5.4 ± 0.3 V, duty cycle 0.006), were produced by ankle rotation from 90 to 40°. Before the stretch protocol, weight‐matched groups had similar isometric forces at an ankle position of 90° at 5, 10, 20, 40, 60 and 80 Hz but forces were lower for age‐matched females. For all groups, normalized force–frequency relationships were similar. During the stretch protocol, deficits for isometric force at 90° and peak stretch force at 40° with stretch number were similar for all groups. One hour after the stretches, isometric force deficits at 90° at 40, 60 and 80 Hz were larger for females in weight‐matched groups (e.g. 80 Hz, female: 47.8 ± 1.7%; male: 41.1 ± 1.7%; P < 0.05), perhaps because of a difference in age (P < 0.05). For age‐matched groups, isometric force deficits at 90° were similar at all frequencies. The susceptibility for force deficits by stretches of activated skeletal muscles was not gender‐dependent for 2‐month‐old rats.
Excitation‐induced Ca2+ influx and skeletal muscle cell damage
Authors: Gissel H. , Clausen T.
Published: March 2003

Excessive exercise may lead to skeletal muscle cell damage with degradation of cellular components and leakage of intracellular enzymes. Calcium has repeatedly been proposed to be involved in these processes. Studies have shown that the resting level of cytoplasmic Ca2+ increases up to threefold during long‐term low‐frequency stimulation. We have shown that electrical stimulation produces a marked increase in Ca2+ uptake and Ca2+ content in rat skeletal muscle, both in vivo and in vitro. Continuous stimulation for 240 min at 1 Hz results in an increased release (18‐fold) of lactate dehydrogenase (LDH) from extensor digitorum longus (EDL) muscle. This was associated with an increased total Ca2+ content (185%), was augmented at high [Ca2+]o and suppressed at low [Ca2+]o. The release of LDH may reflect partial loss of sarcolemmal integrity as a result of degradation of membrane components by Ca2+‐activated enzymes (e.g. calpain or phospholipase A2). After cessation of stimulation the increased release of LDH continues for at least 120 min. This is associated with an up to sevenfold increase in 45Ca uptake. The increased permeability to Ca2+ may further activate calpain and phospholipase A2 and accelerate the loss of membrane integrity. Stimulation‐induced uptake of Ca2+ and release of LDH is most pronounced in EDL (mainly composed of fast‐twitch fibres at variance with soleus which is mainly composed of slow‐twitch fibres). This may account for the observation that prolonged exercise leads to preferential damage to fast‐twitch fibres. We hypothesize that excessive exercise may lead to an intracellular accumulation of Ca2+ and increased cytoplasmic Ca2+ causing activation of self‐accelerating degradative pathways leading to muscle damage.
Muscular effects in late polio
Authors: Sunnerhagen K. Stibrant , Grimby G.
Published: March 2003

New or increased muscular weakness, fatigue and muscle and joint pain with neuropathic electromyography (EMG) changes in a person with a confirmed history of polio constitute the cardinal symptoms of the post‐polio syndrome. Unusual tiredness or fatigue is a common complaint in late polio subjects as is intolerance to cold. Fatigue in polio subjects can have several explanations: emotional fatigue, central nervous system fatigue, ‘general’ fatigue and/or neuromuscular fatigue. Some studies indicate central fatigue, but it is unclear how often and to which degree there will be a central muscular fatigue. Polio patients are known to be deconditioned (reduced function because of low activity level), and aerobic power is reduced. Defects in the neuromuscular transmission may be present but are not seen in all post‐polio subjects with reduction in force and increased fatigability. The fatigue experienced by late polio patients is most likely an augmented peripheral muscle fatigue. Possible explanations may be an imperfection in the sarcoplasmatic reticulum with altered calcium release mechanisms (activation) or in sliding filament function (contractile properties). This may be a secondary effect to the enlarged muscle fibres. However, the prolonged subjective feeling of fatigue reported despite unchanged maximal voluntary contraction (MVC) remains unexplained.
Malignant hyperthermia and excitation–contraction coupling
Authors: Melzer W. , Dietze B.
Published: March 2003

Malignant hyperthermia (MH) is a state of elevated skeletal muscle metabolism that may occur during general anaesthesia in genetically pre‐disposed individuals. Malignant hyperthermia results from altered control of sarcoplasmic reticulum (SR) Ca2+ release. Mutations have been identified in MH‐susceptible (MHS) individuals in two key proteins of excitation–contraction (EC) coupling, the Ca2+ release channel of the SR, ryanodine receptor type 1 (RyR1) and the α1‐subunit of the dihydropyridine receptor (DHPR, L‐type Ca2+ channel). During EC coupling, the DHPR senses the plasma membrane depolarization and transmits the information to the ryanodine receptor (RyR). As a consequence, Ca2+ is released from the terminal cisternae of the SR. One of the human MH‐mutations of RyR1 (Arg614Cys) is also found at the homologous location in the RyR of swine (Arg615Cys). This animal model permits the investigation of physiological consequences of the homozygously expressed mutant release channel. Of particular interest is the question of whether voltage‐controlled release of Ca2+ is altered by MH‐mutations in the absence of MH‐triggering substances. This question has recently been addressed in this laboratory by studying Ca2+ release under voltage clamp conditions in both isolated human skeletal muscle fibres and porcine myotubes.
Autoimmunity against the ryanodine receptor in myasthenia gravis
Authors: Skeie G. O. , Lunde P. K. , Sejersted O. M. , Mygland Å. , Aarli J. A. , Gilhus N. E.
Published: March 2003

Some myasthenia gravis (MG) patients have antibodies against skeletal muscle antigens in addition to the acetylcholine receptor (AChR). A major antigen for these antibodies is the Ca2+ release channel of the sarcoplasmic reticulum the ryanodine receptor (RyR). These antibodies are found mainly in MG patients with a thymoma MG and correlate with severe MG symptoms. The antibodies recognize a region near the N‐terminus on the RyR, which seems to be of importance for RyR regulation. The antibodies cause allosteric inhibition of RyR function in  vitro, inhibiting Ca2+ release from sarcoplasmic reticulum.
Sodium transport deficiency and sodium balance in gene‐targeted mice
Authors: Schnermann J.
Published: March 2003

Animals with induced or natural null mutations in renal NaCl and water transporter genes provide a powerful tool to study the physiological mechanisms that enable the kidney to optimize the match between glomerular filtration rate and tubular reabsorption. Deficiencies in the Na/H exchanger NHE3 and in the water channel aquaporin 1 (AQP1) cause reductions in proximal fluid absorption which are accompanied by proportionate decrements in glomerular filtration rate (GFR). Compensation of the transport defect by a reduction in filtered load is so efficient that clinically symptomatic Na losses are not observed in either NHE3 or AQP1 deficient animals. On the other hand, severe syndromes of salt wasting are caused by loss of function of the Na,K,2Cl‐cotransporter (NKCC2) in the thick ascending limb, or of the epithelial Na channel (ENaC) the collecting duct indicating that the severity of Na dysregulation is unrelated to the basal absorption of NaCl in a given nephron segment. In these states, the increased delivery of Na to downstream segments is not monitored by a sensor linked to the site of filtrate formation. In the absence of adaptations in the filtered load intrarenal compensation of a circumscribed NaCl malabsorption by adjustment of NaCl transport in other nephron segments is sometimes insufficient, particularly in the immature kidney of the newborn.
Cardioprotective actions of acute HMG‐CoA reductase inhibition in the setting of myocardial infarction
Authors: Jones S. P. , Lefer D. J.
Published: March 2003

A known risk factor for the development of coronary artery disease and subsequent myocardial infarction is hypercholesterolaemia. The widespread nature of this phenomenon in the western world has led to the development of agents which reduce serum cholesterol levels. One such class of agents, HMG‐CoA reductase inhibitors (statins) are very effective in cholesterol reduction. Recently, clinical and experimental evidence has amassed suggesting that patients taking statins receive cardiovascular benefits that occur independent of cholesterol reduction. Experimental data suggest that statins may increase levels of nitric oxide (NO) in vivo. This review will address the ‘cholesterol‐independent’ vasculoprotective and cardioprotective effects of statins in animal models. Upon completion, the reader will be familiar with the proposed cholesterol‐independent pathways of statins and understand that the cholesterol‐independent benefits may arise from enhanced production of NO.
Effects of long‐term inhibition of neuronal nitric oxide synthase on blood pressure and renin release
Authors: Ollerstam A. , Skøtt O. , Ek J. , Persson A. E. G. , Thorup C.
Published: March 2003

Nitric oxide (NO) produced by neuronal NO‐synthase (nNOS) in macula densa cells may be involved in the control of renin release. 7‐Nitro indazole (7‐NI) inhibits nNOS, and we investigated the effect of short‐ (4 days) and long‐term (4 weeks) 7‐NI treatment on blood pressure (BP), plasma renin concentration (PRC) and glomerular filtration rate (GFR) in rats on different salt diets. Rats were divided into three groups and given low‐salt (LS), normal (C) and high‐salt (HS) diets. Each diet group was subdivided into two groups treated either with 7‐NI or vehicle. Long‐term 7‐NI‐treated rats (LS and C) showed increased BP compared with controls (LS: 149 ± 4 vs. 133 ± 3; C: 146 ± 4 vs. 127 ± 4 mmHg). Blood pressure in HS rats did not differ from that in controls. Plasma renin concentration was stimulated in LS‐rats (251 ± 64 mGU mL–1) compared with C and HS rats (42 ± 8 and 39 ± 5 mGU mL–1, respectively) but was not significantly affected by chronic 7‐NI treatment (350 ± 103, 49 ± 10 and 50 ± 15 mGU mL–1 in LS, C and HS, respectively). In rats treated with 7‐NI for 4 days, no effect on BP was seen, but PRC was increased in 7‐NI treated LS rats compared with vehicle treated LS rats (107 ± 15 vs. 56 ± 1 mGU mL–1). Stimulation of PRC in LS rats was further enhanced by 7‐NI after 4 days of treatment, but not affected in rats treated for 4 weeks. This suggests that inhibition of nNOS stimulates renin release but that this stimulatory effect in the long run might be depressed by the increase in blood pressure.
Sweating response in physically trained men to sustained handgrip exercise in mildly hyperthermic conditions
Authors: Yanagimoto S. , Aoki K. , Horikawa N. , Shibasaki M. , Inoue Y. , Nishiyasu T. , Kondo N.
Published: March 2003

To investigate the effects of physical training on heat loss response to sustained handgrip exercise (non‐thermal factors), we compared the sweating response during isometric handgrip exercise to mild hyperthermia in physically trained and untrained subjects. Seven trained and untrained male subjects (maximal oxygen uptake 62.7 ± 2.4 and 42.7 ± 1.6 mL kg–1 min–1, respectively, P < 0.05) performed isometric handgrip exercises at 20, 35 and 50% maximal voluntary contraction (MVC) for 60 s. The study was conducted in a climatic chamber with a regulated ambient temperature of 35 °C and relative humidity of 50% to induce sweating response at rest by rising skin temperature without a marked change in internal temperature. Sublingual and mean skin temperatures (thermal factors) in both trained and untrained groups were essentially constant throughout all exercise intensities. Changes in heart rate, mean arterial blood pressure, and rating of perceived exertion with increased exercise intensity were similar in both groups. Sweating rate (SR) on the limbs (mean value of forearm and thigh) was significantly greater in the trained group than in the untrained group at 50% MVC (P < 0.05). In addition, the slopes of the relationship between increased SR and exercise intensity (% MVC) on the trunk (chest) and limbs were significantly greater in the trained group than in the untrained group (P < 0.05). Our results suggest that the sweating response caused by non‐thermal factors against a background of changing thermal factors was enhanced by physical training. It is also thought that the enhanced sweating response may be especially evident on the limbs than on the trunk, such as improvement of sweating response associated with thermal factors.
Respiratory mechanics in mice: strain and sex specific differences
Authors: SCHULZ H. , JOHNER C. , EDER G. , ZIESENIS A. , REITMEIER P. , HEYDER J. , BALLING R.
Published: March 2003

To assess the contribution of genetic background to respiratory mechanics, we developed a ventilator unit to measure lung function parameters in the mouse. We studied two commonly used inbred mice strains originating from Mus musculus domesticus (C57BL/6 and C3HeB/FeJ) and a third strain derived from Mus musculus molossinus [Japanese fancy mouse 1 (JF1)]. The ventilator allows for accurate performance of the different breathing manoeuvres required for measuring in‐ and expiratory reserve capacity, quasi‐static and dynamic compliance, and airway resistance. In combination with a mass spectrometer for monitoring gas concentrations, single‐breath manoeuvres were performed and He‐expirograms obtained, from which dead space volume and slope of phase III were determined. From each strain and each sex, 10, 2‐month old animals were studied immediately after being killed by an intraperitoneal overdose of xylazine and ketamine. C3HeB/FeJ and C57BL/6 exhibited comparable lung volumes. In male C3HeB/FeJ mice, e.g. vital capacity (VC) was 1072 ± 79 μL, inspiratory reserve capacity 782 ± 88 μL, and dead space volume at total lung inflation 216 ± 18 μL. Lung volumes of JF1 were significantly lower (e.g. VC 611 ± 53 μL, P < 0.01) even when normalized to body weight. In all three strains, specific lung volumes were significantly higher in females than in males, possibly explained by a higher oxygen demand during pregnancy and lactation, both of which fill most of their life times. Static compliance in C3HeB/FeJ was 64.3 ± 5.4 μL cmH2O–1. It was smaller in C57BL/6 and JF1 mice, even when related to the lung volume. Analysis of the degree of genetic vs. non‐genetic components of the phenotypic variation revealed that at least 80% of the total variation of lung volumes and static compliance in the mixed population is attributable to genetic differences between individuals. These differences will be verified in further studies by segregation and genetic linkage analysis.
Glucose transporter gene expression in freshly isolated and cultured rat pneumocytes
Authors: MAMCHAOUI K. , MAKHLOUFI Y. , SAUMON G.
Published: March 2003

Alveolar epithelium in situ takes up luminal glucose by cotransport with sodium. Cultured alveolar type II pneumocytes have only sodium‐independent glucose uptake. It is unclear which isoforms are responsible for glucose transport in these cells and why sodium–glucose cotransport activity disappears during culture. GLUT1, GLUT4, GLUT5 and SGLT1 mRNA were detected in freshly isolated rat alveolar type II cells by reverse transcriptase‐polymerase chain reaction. We show that SGLT1 mRNA was 90% lower in cells cultured in plastic wells for 2 or 4 days than in freshly isolated cells. mRNAs coding for the facilitated transporters were reduced from 40% (GLUT1) and 75% (GLUT4 and GLUT5) in cultured cells. Cells cultured at the air–liquid interface better preserved their phenotype as attested by significantly higher surfactant‐associated protein mRNA levels. However, these cells had no higher GLUT1 and SGLT1 gene expression. Thus, alveolar type II cells lose sodium–glucose cotransport activity in part because of a decrease in mRNA levels. These changes in gene expression and/or mRNA stability may be an additional consequence of the shift towards the type I cell phenotype observed in cultured type II pneumocytes.
HSP70 and HSP90 expression in leucocytes after exercise in moderately trained humans
Authors: SHASTRY S. , TOFT D. O. , JOYNER M. J.
Published: March 2003

In this study, we examined expression of heat shock proteins (HSP) 70 and 90 in human leucocytes after moderate‐to‐heavy exercise. We also compared baseline levels of HSP70 and HSP90 in trained (TR) and untrained (UT) subjects. Eleven TR subjects ran on a treadmill for 1 h at 70% of maximal oxygen consumption. The HSP levels were measured prior to exercise and 15 and 24 h after exercise. Baseline HSP levels were also measured in eight UT controls. Fifteen hours and 24 h after exercise, TR subjects showed no significant increases in HSP70 (P > 0.05). The HSP90 levels also did not change (P > 0.05). Baseline HSP70 levels in TR subjects were lower than in UT subjects (2.04 ± 0.51 ng vs. 4.52 ± 0.95 ng, P < 0.05), while HSP90 levels were similar in TR and UT subjects. We conclude that exercise at an intensity that is within normal limits for a moderately trained individual is not a sufficient stimulus of HSP70 production in leucocytes. We also conclude that blunted levels of baseline HSP70 expression in TR subjects might be a chronic adaptation to training.
Sweating responses to a sustained static exercise is dependent on thermal load in humans
Authors: Kondo N. , Horikawa N. , Aoki K. , Shibasaki M. , Inoue Y. , Nishiyasu T. , Crandall C. G.
Published: March 2003

The purpose of this project was to test the hypothesis that internal temperature modulates the sweating response to sustained handgrip exercise. Ten healthy male subjects immersed their legs in 43 °C water for 30–40 min at an ambient temperatures of 30 °C and a relative humidity of 50%. Sweating responses to 50% maximal voluntary contraction isometric handgrip exercise (IH) were measured following the onset of sweating (i.e. following slight increases in internal temperature), and after more pronounced increases in internal temperature. Oesophageal temperature (Tes) was significantly lower during the first bout of exercise (37.54 ± 0.07 °C) relative to the second bout (37.84 ± 0.12 °C; P < 0.05). However, the increase in mean sweating rate (SR) from both the chest and forearm (non‐glabrous skin) was significantly greater during the first IH bout relative to the second bout (P < 0.05). Increases in mean arterial blood pressure and palm SR (glabrous skin) did not differ significantly between exercise bouts, while heart rate and rating of perceived effort were significantly greater during the second bout of IH. As Tes and mean skin temperature did not change during either bout of exercise, the changes in SR from non‐glabrous skin between the bouts of IH were likely because of non‐thermal factors. These data suggest that sweating responses from non‐glabrous skin during IH vary depending on the magnitude of thermal input as indicated by differing internal temperatures between bouts of IH. Moreover, these data suggest that the contribution of non‐thermal factors in governing sweating from non‐glabrous skin may be greatest when internal temperature is moderate (37.54 °C), but has less of an effect after greater elevations in internal temperature (i.e. 37.84 °C).
Local perivascular application of low amounts of a plasmid encoding for vascular endothelial growth factor (VEGF165) is efficient for therapeutic angiogenesis in pigs
Authors: Nikol S. , Engelmann M. G. , Pelisek J. , Fuchs A. , Golda A. , Shimizu M. , Mekkaoui C. , Rolland P. H.
Published: March 2003

Clinical trials have demonstrated therapeutic benefit in inducing angiogenesis in chronic occlusive arterial disease. The route of application mostly used was the intramuscular injection of high dosages of plasmid. Therefore, a local perivascular application of low amounts of vascular endothelial growth factor (VEGF) plasmid was used in an interventional occlusion model, and the effect of VEGF on coronary and peripheral occlusions compared in the same animal model. Coronary and peripheral arteries were chronically occluded in Pietrain pigs using a non‐surgical, interventional approach. Adventitial delivery of the DNA for VEGF was performed with a needle injection catheter. The DNA was applied as lipoplexes using the novel cationic liposomes DOCSPER. Optimized transfer conditions were used. Angiography, polymerase chain reaction (PCR), reverse transcriptase‐polymerase chain reaction (RT–PCR) and immunohistochemistry were undertaken within a follow‐up period of 6 months. Expression of the transfected VEGF gene was observed at 1 and 3 weeks following application. The DNA was detected up to 5 months following application. Around occluded coronary arteries, there was formation of new collaterals and arterial prolongation, whereas surrounding occluded peripheral arteries there was no collateralization but development of new arterial branches was seen. Results demonstrate that the response to VEGF is also sufficient, when minimal amounts of plasmid encoding for VEGF are applied locally into the perivasculature allowing for more safety of this therapy. Comparison of treatment of chronic coronary and peripheral arterial disease revealed differences in angiogenesis following VEGF application during a total follow‐up period of almost 6 months which may be related to their different developmental origins. This may have important implications for developing future therapeutic strategies using VEGF in different vessels.
Unaltered oxygen tension in rat pancreatic islets despite dissociation of insulin release and islet blood flow
Authors: Carlsson P.‐O. , Jansson L. , Palm F.
Published: March 2003

The present study investigated the importance of a tightly regulated islet blood flow for an optimal oxygenation of the islet tissue during different demands for insulin release. Glucose and/or a non‐specific nitric oxide synthase inhibitor (l‐NNA) were infused intravenously in non‐pretreated or vagotomized rats and the animals were subjected to measurements of islet blood flow, oxygen tension and serum insulin concentrations. Islet blood flow was measured using a non‐radioactive microsphere technique, tissue oxygen tension was recorded with Clark microelectrodes and insulin concentrations were determined by enzyme‐linked immunosorbent assay technique. Administration of l‐NNA (0.3 mg kg−1 min−1) for 10 min halved basal islet blood flow, but did not affect serum insulin concentrations. Glucose administration (10 mg kg−1 min−1) induced a marked increase in islet blood flow, which could be prevented by vagotomy or l‐NNA. The serum insulin concentrations increased in all glucose‐infused animals. The islet tissue oxygen tension remained similar in all animals despite these interventions. Reasons other than oxygenation of the islet tissue must explain the normally existing tight regulation of islet blood flow.
Role of prostaglandin cyclooxygenase and cytochrome P450 pathways in the mechanism of natriuresis which follows hypertonic saline infusion in the rat
Authors: Kompanowska‐Jezierska E. , Walkowska A. , Sadowski J.
Published: March 2003

Abstract Aim:  The prostaglandin cyclooxygenase (COX) and P450 cytochrome (CYP450) pathways of arachidonic acid metabolism are functionally interrelated and both engaged in control of sodium excretion; the study focused on their contribution to the natriuresis which follows hypertonic saline infusion in the rat.

Methods:  In anaesthetized rats, clearance studies were conducted, supplemented with laser‐Doppler measurements of the cortical and medullary blood flow (CBF, MBF), and measurement of medullary tissue admittance (Y), an index of interstitial ion concentration.

Results:  Indomethacin (Indo), 5 mg kg−1 i.v. paradoxically enhanced the natriuresis secondary to intra‐aortic suprarenal 5% saline load, further increasing sodium excretion by 385 ± 73% (P < 0.01). After acute clotrimazole, 10 mg kg−1 i.v. an inhibitor of CYP450 epoxygenase, the increase in natriuresis was smaller and did not differ from that observed after the drug's ethanol solvent. In rats pre‐treated with clotrimazole for 3 days, hypertonic saline loading increased sodium excretion (UNaV) to 0.94 ± 0.22 μmol min−1, compared with a significantly greater (P < 0.05) increase to 2.76 ± 0.48 μmol min−1 measured in untreated controls. Indo increased UNaV twofold, similarly in the clotrimazole and in the control group; in the absence or presence of clotrimazole treatment, COX blockade significantly decreased MBF and increased Y.

Conclusion:  The data indicate that blockade of the CYP450 epoxygenase significantly impairs excretion of sodium in rats acutely loaded with hypertonic NaCl solution. The paradoxical post‐Indo natriuresis is preserved in clotrimazole treated rats, which speaks against the role of CYP450 pathway in the response.
Are pre‐ganglionic neurones recruited in a set order?
Authors: McAllen R. M. , Trevaks D.
Published: March 2003

Aim:  The idea that, like somatic motor neurones, sympathetic pre‐ganglionic neurones are engaged to fire in a pre‐determined recruitment order, was investigated in chloralose‐anaesthetized cats.

Method:  Ongoing pre‐ganglionic spike activity was recorded from fine filaments of otherwise intact thoracic white rami, while post‐ganglionic activity was recorded from the whole inferior cardiac nerve (ICN). Spikes of individual pre‐ganglionic fibres were extracted from few‐fibre recordings by spike shape analysis. Presumed cardiac pre‐ganglionic fibres were further selected by the spike‐triggered average of ICN activity, which showed a clear peak when triggered by their spikes.

Results:  To test whether particular pre‐ganglionic neurones were recruited to fire in a set time sequence, the spontaneous spike trains of fibres in the same white ramus were compared by cross correlation. In all 24 cases the cross correlograms showed a central peak (width 163 ± 15 ms), indicating that the two neurones tended to fire together. In 23 of the 24 cases that peak spanned the zero point on the time axis, showing that each neurone could fire either first or second. To test whether pre‐ganglionic neurones were recruited in a set order with respect to burst amplitude, the firing of individual pre‐ganglionic neurones was compared with the strength of the corresponding post‐ganglionic burst discharge, on a heartbeat‐by‐heartbeat basis. Pre‐ganglionic neurone firing was probabilistic: each neurone fired with only a minority of post‐ganglionic bursts. Firing probability increased linearly with burst amplitude (30 of 30 cases). The slope of the relation varied between units, but its intercept was always close to the origin (zero pre‐ganglionic firing probability at zero post‐ganglionic burst size).

Conclusion:  The data indicate that, at least under these conditions, sympathetic pre‐ganglionic neurones follow no set recruitment sequence in either their firing times or with respect to the strength of the autonomic motor output.
Diet and habitat overlap in two sympatric primate species, the Tana crested mangabey Cercocebus galeritus and yellow baboon Papio cynocephalus
Authors: WAHUNGU GEOFFREY
Published: March 2003

Diet and habitat overlap was studied in two sympatric primate species sharing two neighbouring patches of fragmented gallery forest in Tana River, Kenya. Systematic data on feeding and ranging behaviour was collected on one group each of the Tana crested mangabey Cercocebus galeritus and yellow baboon Papio cynocephalus between August 1992 and February 1993. When rainfall was low and fruit resources scarce, yellow baboons spent most of their foraging time in the open woodlands while mangabeys foraged within the forest. At this period, diet and habitat overlaps between the two species were low. As rainfall increased, followed by a gradual rise in fruit availability, yellow baboons shifted their foraging range and both species became confined to the forest habitat. Consequently, both diet and habitat overlaps increased, peaking at the end of the rainy season. Mangabeys showed a reduced within‐group dispersal and also spent significantly less time foraging in a given forest patch when yellow baboons were also present within the same forest patch.

Increased habitat and diet overlaps during the wet season need not have resulted in increased interspecific competition for food because at this period, fruits were readily available in the forest.
Diet of striped hyaena in northern Kenya
Authors: Leakey L. N. , Milledge S. A. H. , Leakey S. M. , Edung J. , Haynes P. , Kiptoo D. K. , McGeorge A.
Published: March 2003

A study of striped hyaena (Hyaena hyaena (Linnaeus, 1758)) in Lothagam, northern Kenya was conducted to understand the interactions of H. hyaena with the local Turkana people and their livestock. Data were collected from skeletal parts, fresh scats, ecological survey, and from interviews at different homesteads. Analysis of skeletal remains was broadly divided into three categories: species, skeletal part and bone damage. Insects, birds, fish, crocodile, seeds, leaves and fifteen species of mammalian prey were identified. The high proportion of livestock, dog and human remains in the bone accumulations indicate a significant dependence on the lifestyles of the local Turkana people. The study provides evidence to suggest that striped hyaenas predate on small livestock and demonstrate an opportunistic behaviour, which enables them to survive as the largest carnivore in this marginal environment. A greater abundance of bones are associated with striped hyaena dens than with those of the spotted hyaena (Crocuta crocuta (Erxleben, 1777)). Bone modification by the striped hyaena differs from spotted hyaena bone modification. Bone breakage patterns can be attributed to the relative specific gravity, degree of epiphyseal closure and nutritive fat content of bones.
Species richness of arachnids associated with Protea nitida (Proteaceae) in the Cape fynbos.
Authors: Visser D. , Wright M. G. , Van den Berg A. , Giliomee J. H
Published: March 2003

Regular counts of Arachnida on Protea nitida Mill. were made in three study areas in the western Cape over a period of one year. They were also investigated in the rest of the natural distribution area of P. nitida in the southern and western Cape. Collections were made according to three standardized methods. Five arachnid orders were collected, of which the Araneae (spiders) were dominant. Thirty‐two spider species (653 individuals) representing 18 families were collected, of which five families and eight genera (eight species) were recorded for the first time on the Proteaceae in the Cape fynbos. Four non‐Araneae orders were collected. A microhabitat preference was observed in some families. Numbers of immature spiders peaked in autumn. Adults and immatures did not always have the same habitat distribution and did not always peak during the same season. Families also showed differences in seasonal abundance. Plant architecture and distribution influenced the number of species collected. Protea nitida hosted more spider species than less complex plants with smaller distributions. The implications of these findings are discussed in terms of biodiversity and invertebrate conservation.
Effects of amendments on biodegradation of crude petroleum by sediment bacteria from Bonny River Estuary
Authors: Adoki A. , Sokari T. G. , Ibiebele D. D.
Published: March 2003

The biodegradation of Bonny light crude petroleum by bacteria in batch culture was enhanced by the addition to culture media, of 0.2 mg of urea and soya bean lecithin per 100 ml of crude oil, sediment and water mixture. Biodegradation was found to be purely an aerobic process. There was a direct relationship between hydrocarbon content and proportion (%) of total heterotrophic count that was capable of growing on crude petroleum as sole carbon and energy source.
The economic costs of wildlife predation on livestock in Gokwe communal land, Zimbabwe
Authors: Butler J. R. A.
Published: March 2003

In areas bordering wildlife reserves in Zimbabwe, agro‐pastoralists suffer livestock depredation by wild carnivores. However, the economic value of these losses, and therefore the levels of compensation required has never been calculated. Between January 1993 and June 1996 in a 33‐km2area of Gokwe communal land bordering the Sengwa Wildlife Research Area, 241 livestock were killed by wild carnivores. Baboons (Papio ursinusKerr), lions (Panthera leoLinnaeus) and leopards (P. pardusLinnaeus) were the most serious predators, contributing 52%, 34% and 12% of kills, respectively. Baboons only killed young goats (Capra hircusLinnaeus) and sheep (Ovis ariesLinnaeus) by day, while lions and leopards jumped into fortified kraals at night and killed cattle (Bos indicusLinnaeus), donkeys (Equus asinusLinnaeus) and smallstock. In 1995, predators killed 5% of livestock holdings, double that recorded by other African studies. The annual total value of losses depended upon the degree of lion predation on the most valuable species, cattle and donkeys. The average annual loss per livestock‐owning household was US$13, or 12% of each household's net annual income. Losses could be reduced by improving kraal defences against lion and leopard predation in the dry season, when attacks were most common.
The social organization of giraffes in Niger
Authors: Le Pendu Yvonnick , Ciofolo Isabelle , Gosser Allen
Published: March 2003

The social organization of the last population of giraffes (Giraffa camelopardalis) in West Africa was studied between October 1996 and December 1997. Population size increased from 51 to 63 individuals during the study period. Groups were larger during the rainy season (mean group size 9.4) than during the dry season (mean group size 6; U = 4131; P < 0.01). Giraffes did not show strong preferential associations. Group types observed were similar to those expected on the assumption that associations are independent of sex and age. Inter‐individual associations were low (mean simple ratio value = 0.1), with an individual associating with only half of its partners of the previous day. Young males interacted more frequently than other classes did. Agonistic interactions occurred mostly among males. Contact interactions (i.e. non‐agonistic or sexual) occurred between both sexes and most age classes. Links between local communities, domestic animals, fauna and the environment suggest that environment and development cannot be dissociated in the sustainable exploitation of natural resources.
The influence of large mammalian herbivores on growth form and utilization of mopane trees, Colophospermum mopane, in Botswana’s Northern Tuli Game Reserve
Authors: Styles C. V. , Skinner J. D.
Published: March 2003

Mopane veld is of great value to the general ungulate spectrum in times of drought, and it is capable of retaining its dominance in a community even in the presence of extremely heavy browsing pressure imposed by large browsing mammals. Scrub mopane (hedges) has been regarded as resulting from excessive browsing pressure by large mammals, especially elephants. Both the nutrient and chemical composition of mopane twig bark were investigated, the seasonal results being related back to the seasonal utilization of branches by large mammals. Mopane twigs were most palatable in winter. Eland feed on mopane throughout the year irrespective of palatability. Elephants were rarely present in the scrub mopane area before the onset of spring rains, when the major mopane leaf flush occurs independently of rainfall. The impact of both species was not excessive and recruitment of mopane seedlings does occur. Herbivore browsing is responsible for a mopane morph which buds early and continues to produce accessible, nutritious leaves even when heavily browsed. Many browsing ungulates are reliant on this resource during the stressful transition from spring to summer in south‐eastern Botswana.
Growth and carapacial colour variation of the leopard tortoise, Geochelone pardalis babcocki, in northern Tanzania
Authors: Kabigumila J.
Published: March 2003

Observations were made of growth rate and variation in colour pattern of the leopard tortoise (Geochelone pardalis babcocki) in northern Tanzania between October 1993 and June 1996. Growth rate differed significantly between tortoises, with immature animals (6.9 ± 1.4 mm month−1) and females (5.7 ± 1.3 mm month−1) exhibiting higher rates of growth than adult animals (2.9 ± 0.8 mm month−1) and males (3.2 ± 1.1 mm month−1), respectively. The faster growth rate in immature animals suggested that growth rate declined with age. The difference in growth rates between the sexes was ascribed to sexual dimorphism, adult females being larger and therefore growing faster than males.

The carapacial colour pattern observed in the northern Tanzanian tortoises was generally similar to that described elsewhere in the species' range. The colour pattern varied between Arusha and Serengeti District tortoises. Animals at the Arusha sites tended to be sparsely coloured (55.6%) compared to the Serengeti tortoises, which had a buff colouration with radiating spots (89.3%).; The sparse colouration provides effective camouflage in the drier Arusha habitats, as does the buff colouration with black spots in the wetter, darker habitats in the Serengeti.
Tree population dynamics in Kibale National Park, Uganda 1975–1998
Authors: Lwanga Jeremiah S. , Butynski Thomas M. , Struhsaker Thomas T.
Published: March 2003

Changes in species composition, stem abundance, and basal area of trees taller than or equal to 10 m in a medium altitude tropical rain forest at the Ngogo study area, Kibale National Park, Uganda are described for the period between 1975 and 1998 (n = 23 years). Two enumeration episodes were conducted in 263 plots of 5 m by 50 m during 1975–80 and 1997–98. During this period, species richness decreased by 3% (from 92 to 89). Species diversity (H′) also declined slightly from 2.97 to 2.86. The number of trees recorded in the sample plots decreased by 8% (from 2545 to 2329), while basal area decreased from 49.48 m2 ha−1 to 48.68 m2 ha−1. However, stem abundance and basal area increased for some species.
Nutritional ecology of Preuss's red colobus monkey (Colobus badius preussi Rahm 1970) in Korup National Park, Cameroon
Authors: Usongo Leonard I. , Amubode Felix O.
Published: March 2003

Studies on the nutritive ecology of red colobus monkeys (Colobus badius preussi) in Korup National Park, Cameroon, investigated food plants and the parts eaten as well as nutritive values of the various food items. Food plants were identified through direct observations and collected for laboratory determination of nutrient content. Food plants were analysed for crude protein (CP), crude fibre (CF), ether extract (EE), nitrogen‐free‐extractive (NFE) and total ash (A).

A total of seventeen species belonging to nine different families were identified as food plants for red colobus. Food and feeding habits showed that the species were highly folivorous, tending to prefer the young leaves of food plants. Lecomtedoxa klaineana (27.0%) and Xylopia aethiopica (22.2%) of families Sapotaceae and Annonaceae, respectively, constituted about 50% of total food items consumed. Results of nutrient composition indicated individual nutrients varied significantly (P < 0.01) with food species.
Estimating forest elephant density in Sapo National Park (Liberia) with a rainfall model
Authors: Barnes R. F. W. , Dunn Andrew
Published: March 2003

The number of elephant dung‐piles lying on the forest floor is a function of the number of elephants present and the rainfall in the 2 preceding months. We present the results of a stochastic model that describes this relationship and we show how it can be used to estimate elephant numbers. The data from a survey in Sapo NP (Liberia) in 1989 are used as an example. The dung‐pile density was estimated at 152 km−2with confidence interval from 72 to 322, and the number of elephants was estimated to be 313 with confidence interval from 172 to 617.