bluuebunny/crossref_metadata_2025 huggingface dataset:
Myocardial lactate release during prolonged exercise under hypoxaemia
Authors: KAIJSER L. , GRUBBSTRÖUM J. , BERGLUND B.
Published: December 2008

The possible appearance of myocardial lactate production during exercise under hypoxaemia, simulating an altitude of about 4500 metres above sea‐level (masl) was investigated. Twelve healthy men were studied, after coronary sinus catheterization, during prolonged exercise breathing 12% 02 compared with men breathing air. Coronary sinus blood flow was measured by thermodilution. Exercise duration under each breathing condition was 30 min and the order normoxaemia/hypoxaemia was varied between subjects so as to compensate for any influence of a preceding exercise period on a subsequent one. Work load was adjusted so as to produce a heart rate (HR) of 130–140 beats min‐1 during both hypoxaemia and normoxaemia. [14C]lactate was infused at a constant rate i.v. throughout the study to detect a possible myocardial lactate release simultaneously with a net uptake. Myocardial 02 uptake did not differ significantly between hypoxaemia and normoxaemia. The compensation for reduced blood oxygen content was achieved entirely by a greater coronary blood flow. Yet, the arterial‐coronary sinus (a‐cs) lactate difference was lower during hypoxaemia than normoxaemia and isotope data indicated that this was caused by a myocardial lactate release of approximately 90 μmol min‐1 which was at hand during hypoxaemia but not normoxaemia, whether hypoxaemic exercise preceded or succeeded normoxaemic exercise. In conclusion, A 27% reduction in arterial oxygen saturation is almost compensated for by an increased coronary blood flow. However, during hypoxaemic exercise cardiac energy demand is to a smaller part, about 1 %, covered by anaerobic metabolism.
Allergen‐induced airway obstruction in guinea‐pigs is associated with changes in nitric oxide levels in exhaled air
Authors: PERSSON M. G. , GUSTAFSSON L. E.
Published: December 2008

Endogenously produced nitric oxide (NO) was monitored in exhaled air from ovalbumin‐sensitized and pentobarbital anaesthetized guinea‐pigs. Stable levels of nitric oxide were detected in exhaled air over a 30‐min control period in each experiment (9.2 ±1.4 parts per billion, [ppb]). Insufflation pressure and NO in exhaled air immediately increased, in a dose dependent manner, in response to challenge with nebulized allergen (Ovalbumin, 0.1–10 mg). Indomethacin (5 mg kg‐1) augmented the allergen‐induced increases in insufflation pressure and NO. Fifteen min after the challenge the insufflation pressure remained elevated while NO in exhaled air had dropped below control levels. The increase in insufflation pressure induced by inhalation of PGF2a(5 μg) was accompanied by an increase in nitric oxide in exhaled air, which however was significantly less than the increase in NO induced by allergen challenge. The results suggest a role for NO mechanisms in asthma.
Immobilization stress induces vasodepressor and altered neuroendocrine responses in the adult stroke‐prone spontaneously hypertensive male rat
Authors: NARVAEZ J. A. , AGUIRRE J. A. , HARFSTRAND A. , ENEROTH P. , GANTEN D. , AGNATI L. F. , FUXE K.
Published: December 2008

The effects of acute (1 h) and daily repeated immobilization stress (14 days, twice‐daily, 1 h) were studied on arterial blood pressure and heart rate and on the blood levels of several hormones in the adult (5 months old) stroke‐prone spontaneously hypertensive rat (SHRSP) and in the age‐matched normotensive Wistar‐Kyoto (WKY) rat. The major result was the development of a long‐lasting vasodepressor response in the SHRSP, while the same acute or repeated immobilization stress in the WKY rat led to the development of a prolonged vasopressor response. Differential changes to stress were also observed in practically all neuroendocrine axes with the exception of the pituitary‐adrenal axis. The vasodepressor response to immobilization stress in SHRSP may be related to an exaggerated defence‐like reaction causing an enhanced vasodilation in the skeletal muscle beds associated with a tachycardia similar to that in the normotensive control rats.
Effect of hypoxic hypoxia and ritanserin on capillary flow and oxygenation in rabbit skeletal muscle
Authors: GUSTAFSSON U. , SJOBERG F. , LEWIS D. H. , THORBORG P.
Published: December 2008

Gustafsson, U., Sjöberg, F., Lewis, D. H. & Thorborg, P. 1994. Effect of hypoxic hypoxia and ritanserin on capillary flow and oxygenation in rabbit skeletal muscle. Acta Physiol Stand 150, 39–45. Received 2 April 1993, accepted 21 July 1993. ISSN 0001–6772. Clinical Research Centre and the Burns Unit, Department of Hand and Plastic Surgery, and Department of Anaesthesiology, University Hospital, Linkoping, Sweden, and Dept of Anesthesiology, University of Rochester Medical Center, NY, USA.

This study examined capillary flow and oxygenation in rabbit skeletal muscle during hypoxic hypoxia (inspired oxygen fraction = 0.10) and after administration of ritanserin (highly selective 5‐Hydroxytryptamine‐2‐receptor antagonist). Capillary flow (hydrogen clearance) or oxygen pressure was measured with a multiwire micro‐electrode which was placed on the surface of the left vastus medialis muscle. For measurement of regional microcirculatory blood flow a laser‐Doppler flowmeter probe was placed on the contralateral muscle. An experimental sequence with normoxaemia (arterial Po2 12.5 kPa), followed by hypoxaemia (arterial Po2 3.9 kPa) and thereafter sustained hypoxaemia (arterial Po2 4.0 kPa) during which ritanserin (0.035 mg kg‐1 i.v.) was administered, was used. During hypoxaemia a decrease was seen in mean arterial pressure (MAP) by 27%, capillary flow by 25%, muscle oxygen pressure by 32% and laser‐Doppler flowmetry (LDF) flow by 24%. After the administration of ritanserin the mean arterial pressure was further reduced by 7%, whereas the capillary flow increased by 59% and the muscle oxygen pressure by 31 %. The LDF flow remained unchanged. These results demonstrate that, in this animal model, a decrease in skeletal muscle capillary flow and oxygenation during hypoxaemia can be reversed by the administration of ritanserin, despite a further reduction in blood pressure.
Changes in slow axonal transport of tubulin induced by local application of colchicine to rabbit vagus nerve
Authors: ARCHER D. R. , DAHLIN L. B. , McLEAN W. G.
Published: December 2008

Archer, D. R., Dahlin, L. B. & MCLEAN, W. G. 1994. Changes in slow axonal transport of tubulin induced by local application of colchicine to rabbit vagus nerve. Acta Physiol Scand150, 57–65. Received 15 April 1993, accepted 30 July 1993. ISSN 0001–6772. Department of Pharmacology and Therapeutics, University of Liverpool, UK and Department of Hand Surgery, Lund University, Malmo, Sweden.

The biochemical and morphological responses of the rabbit vagus nerve to local application of colchicine and to nerve crush were investigated. Fourteen days after the cervical vagus nerve had been crushed or subjected to local application of colchicine for 2 h, nodose ganglia of anaesthetized rabbits were either injected with [35S]methionine or [3H]leucine for studies of slow and fast axonal transport, respectively, or prepared for light microscopical examination. The radio‐labelled proteins of the faster of the two slow transport groups (SCb; 25–30 mm day1) were separated by one‐ or two‐dimensional polyacrylamide gel electrophoresis and both radio‐labelled tubulin and actin were quantified by densitometry from resulting fluorographs of gels. A relative increase in radio‐labelled tubulin was found in SCb in the crushed and colchicine‐treated nerves; this increase persisted for up to 50 days after nerve crush. Morphological changes in nerve cell bodies induced by colchicine were similar, but smaller in magnitude than those in crushed nerves. It is concluded that a temporary arrest of axonal transport produced by colchicine can lead to a redistribution of tubulin transport comparable with that found in regenerating nerve.
Modulation of neuroeffector transmission in guinea‐pig pulmonary artery and vas deferens by exogenous nitric oxide
Authors: CEDERQVIST B. , GUSTAFSSON L. E.
Published: December 2008

Cederqvist, B. & Gustafsson, L. E. 1994. Modulation of neuroeffector transmission in guinea‐pig pulmonary artery and vas deferens by exogenous nitric oxide. Acta Physiol Scand150, 75–81. Received 11 March 1993, accepted 30 July 1993. ISSN 0001–6772. Department of Physiology and Institute of Environmental Medicine, Karolinska Institute, Stockholm, Sweden.

Blockade of nitric oxide (NO) synthesis enhances contractile responses to transmural nerve stimulation in guinea‐pig pulmonary artery, indicating neuromodulation by endogenous nitric oxide. In the present study, neuromodulatory effects of exogenous NO were examined in guinea‐pig pulmonary artery and vas deferens. Application of NO as acid nitrite, to the guinea‐pig pulmonary artery, inhibited the contractile response to transmural nerve stimulation as well as contractions to exogenous noradrenaline. The inhibition occurred in a dose‐dependent manner. Acid nitrite did not affect stimulation‐induced release of [3H]noradrenaline in guinea‐pig pulmonary artery. In the guinea‐pig vas deferens, contractile ‘twitch’ responses to brief (25 pulses) transmural nerve stimulation and stimulation‐induced release of [3H]noradrenaline was unaffected by acid nitrite. However, ‘twitch’ responses to prolonged stimulation were inhibited by acid nitrite, and tonic ‘hump’ responses were either enhanced or unaffected by acid nitrite. In conclusion, exogenous nitric oxide exerted an inhibition of adrenergic neurotransmission post‐junctionally in guinea‐pig pulmonary artery. In guinea‐pig vas deferens, exogenous nitric oxide affected adrenergic and/or non‐adrenergic non‐cholinergic neurotransmission in a complex fashion, however without alteration in noradrenaline release. The data support a role for NO in modulation of neuroeffector transmission, especially by modulation of effector sensitivity, whereas modulation of noradrenaline release seems an unlikely role for NO in these and similar peripheral tissues.
Depletion of secretory granules from the feline parotid gland: action of NANC transmitters per se
Authors: EKSTRÖM J. , ASZTÉLY A. , HELANDER H. F. , TOBIN G.
Published: December 2008

Ekstrom, J., Asztély, A., Helander, H. F. & Tobin, G. 1994. Depletion of secretory granules from the feline parotid gland: action of NANC transmitters per se. Acta Physiol Scand 150, 83–88. Received 5 May 1993, accepted 30 July 1993. ISSN 0001–6772. Department of Pharmacology, University of Goteborg, and Astra Hassle AB, Molndal, Sweden.

A parotid acinar degranulation of approximately 60 and 40% was observed in cats under pentobarbitone anaesthesia after a 90‐min period of continuous stimulation of the parasympathetic auriculo‐temporal nerve at 10 Hz in the absence and presence of atropine, respectively. Atropine completely abolished the large fluid response of the gland to the nerve stimulation. In the non‐atropinized cats, bethanechol, infused into the carotid artery at a dose rate evoking a salivary flow similar to that in response to parasympathetic nerve stimulation, caused an acinar degranulation of approximately 25% and acinar vacuolation. Vasoactive intestinal peptide (VIP; 0.5 μg kg‐1 min‐1 also infused into the carotid artery for 90 min) caused an acinar degranulation of the same magnitude as the parasympathomimetic drug but the peptide did not give rise to any fluid secretion or vacuole formation. The experiments were performed in the presence of α‐ and β‐adrenoceptor blockers. Thus, in parotid glands of the cat, producing no overt secretion of fluid, non‐adrenergic, non‐cholinergic (NANC) mechanisms may be at work causing exocytosis of the acinar granules. These mechanisms are also likely to contribute to the secretion of granules in response to parasympathetic nerve activity in the absence of blockade of the classical autonomic receptors.
Effect of glucose‐6‐phosphate and pH on glucose transport in skeletal muscle plasma membrane giant vesicles
Authors: KRISTIANSEN S. , WOJTASZEWSKI J. F. , JUEL C. , RICHTER E. A.
Published: December 2008

The effect of glucose‐6‐phosphate (G‐6‐P) and pH on glucose transport was studied in skeletal muscle plasma membrane giant vesicles containing GLUT4 but not GLUT1. Vesicles (average diameter 7.6 μm) were obtained by collagenase treatment of muscle. The vesicles were incubated with 10 mmol T‐1 G‐6‐P and, after 0.5 and 2 h of incubation, the intravesicular G‐6‐P concentration was 0.93 ± 0.4 mmol 1‐1 and 1.18 ± 0.5 mmol I“1 (mean ± SE, n = 4), respectively. In order to increase the intravesicular G‐6‐P concentration, 0.001% saponin was added during incubation, which increased the 2‐h intravesicular G‐6‐P concentration to 4.57±1.0 mmol 1‐1 (n = 4). Initially, vesicles were used for glucose transport studies after 30 min of incubation with 10 mmol 1‐1 of G‐6‐P. There was no effect of G‐6‐P on either the affinity constant (Km) or maximal velocity (Vmax) of the glucose transport.

Subsequently, vesicles were incubated for 2 h with 10 mmol T‐1 of G‐6‐P and 0.001 % saponin. Still no effect of G‐6‐P on glucose transport could be detected. In contrast, the rate of D‐glucose transport was affected, when extravesicular pH was varied from 6.0 to 7.8. The maximum glucose transport rate was found at pH 7.2 and was decreased at both higher and lower pH.

It is concluded that G‐6‐P has no effect on GLUT4 intrinsic activity in rat skeletal muscle plasma membrane. In contrast, GLUT4 intrinsic activity is sensitive to changes in pH.
Duodenal wall motility, mucosal net fluid and alkaline secretion in response to luminal acid: role of the vagal nerves and cholinergic transmission
Authors: FÄNDRIKS L. , HAMLET A. , JÖNSON C.
Published: December 2008

Experiments were performed on chloralose anaesthetized cats. Biliary and pancreatic secretions were diverted by separate cannulation of each duct. A 2‐cm segment of the proximal duodenum was isolated between two luminally situated balloons and perfused with isotonic saline containing 14C‐PEG 4000 as a non‐absorbable marker. The perfusate was analysed with regard to alkalinity (back titration) and concentration of marker (liquid scintillation). Net alkalinization and net fluid transport were calculated with conventional equations. Motor activity in the duodenal wall was recorded as changes in volume of the proximal balloon. Exposing the duodenal segment of 30 mM HC1 induced duodenal contractions, net fluid secretion and an increased alkaline secretion, responses which were insensitive to acute truncal vagotomy. The acid‐induced increase in contraction frequency was inhibited by hexamethonium, but not by atropine. Alkaline secretion in response to luminal acid was blocked by hexamethonium and inhibited by atropine, whereas the net fluid secretion was insensitive to these compounds. It is concluded that luminal exposure to hydrochloric acid changes the duodenal functional state by mechanisms which are independent of the extrinsic neural supply. Duodenal contractions during luminal acid exposure, and the alkalinization after such acid exposure, are mediated via local neural pathways, involving a nicotinic cholinergic step and, to some degree, muscarinic transmission. The mucosal volume secretion, however, appears to be mediated by non‐conventional mechanisms.
A method for analysis of cellular K–transport mechanisms through thallium (201TI) uptake in human lymphocytes
Authors: BRISMAR T. , LEFVERT A. , JONDAL M.
Published: December 2008

Thallium (Tl) is the K–congener with the highest specific affinity to K–binding sites and the largest permeability in K–channels, and its usefulness for analysis of cellular K–transport mechanisms was investigated. The uptake of 201T1 was measured in cultured human lymphocytes (Jurkat cells and EBV–transformed B–cells) after various incubation conditions. In a complete culture medium the half–time of the Tl–uptake was 10 min at 37 oC and the steady state accumulation ratio (intracellular/extracellular) was c. 50. The steady state ouabain sensitive uptake was 81% in complete culture medium, it was reduced after substitution with Ringer solution and by a decrease in temperature (from 37 to 22 oC). The ouabain resistant uptake was higher at 22 oC than at 37 oC and it was almost completely inhibited in Na–free or Cl–free solution and by furosemide. The present results indicate that there are only two major routes for K–uptake in lymphocytes and that 201T1 may be a useful substitute for K in the analysis of cellular K–transport mechanisms.
Differences in ultrastructural and metabolic profiles within the same type of fibres in various muscles of young and adult rats
Authors: TAKEKURA H. , KASUGA N. , YOSHIOKA T.
Published: December 2008

Single fibres from tibialis anterior, extensor digitorum longus, gastrocnemius and soleus muscles in young (4–week–old) and adult (35–week–old) Wistar male rats were classified into three types on the basis of their enzyme–histochemical features: slow–twitch oxidative (SO), fast–twitch oxidative and glycolytic (FOG) and fast–twitch glycolytic (FG) fibres. Ultrastructural (volume density of mitochondria: Vmt and Z line width) and metabolic (phosphofructokinase: PFK and succinate dehydrogenase: SDH activities) profiles were measured. PFK activity in all types of fibres1 was higher in adult rats, and the difference between the two age–groups (adult/young) was largest between FG, FOG and SO fibres respectively. SDH activity and Vmt were lower in adult rats in a similar way in all fibres. A significant positive correlation was observed between the Vmt and SDH activity in both age–groups. This positive correlation was very specific in fast–twitch and slow–twitch fibres. Changes in the Vmt did not relate directly to the changes in fibre cross–sectional area. The overall pattern indicates that glycolytic capacity of fast–twitch fibres in flexor muscles (TA and EDL) is higher than in extensor muscles (GC and SOL), and that oxidative capacity of all types of fibre in extensor muscles is higher than in flexor muscles. These profiles were changed by growth, and may be related to the specific differences in pattern of activity of each skeletal muscle, and may reflect differences in the recruitment order of different muscles.
Temperature‐dependence of rod photoresponses from the aspartate‐treated retina of the frog (Rana temporaria)
Authors: DONNER K. , Ä S. HEMIL , KOSKELAINEN A.
Published: December 2008

The effects of temperature changes on rod photoresponses were studied by recording the aspartate‐isolated mass receptor potential in the dark‐adapted retina of the frog Rana temporaria. The amplitude of saturating responses, indicating the magnitude of the dark current, increased linearly with temperature in the measured range 6–26 °C, extrapolating to zero dark current at O °C. Sensitivity was maximal around 18 °C but the decrease towards lower temperatures was shallow. The results show that rod phototransduction in the frog Rana temporaria is adapted to lower temperatures than in the tropical road Bufo marinus. Responses to dim flashes were, approximately up to peak, well fitted by the same ‘independent activation’ model with four delay stages as have been found to best describe current responses from single toad rods. The kinetics (reciprocal time‐to‐peak) showed Arrhenius‐type temperature‐dependence with apparent activation energy 12.4 kcal mol‐1 and Q10 = 2.1.
Inhibition of H,K‐ATPase and Na,K‐ATPase by DIDS, a disulphonic stilbene derivative
Authors: VEGA F. V. , CABERO J. L. , MÅRDH S.
Published: December 2008

Disulphonic stilbenes are effective inhibitors of an anion exchanger which is present in the plasma membranes of many cells (Cabantchik et al. 1978). In the present stud?, the effects of 4, 4′‐diisothiocyano‐2,2′‐disulphonic stilbene acid (DIDS) on the transport activity of the hydrochloric acid pump isolated from pig stomach (H,K‐ATPase, EC 3.6.1.36) were tested. Half‐maximal inhibition of proton transport carried out by the H,K‐ATPase in the isolated vesicles was observed at micromolar concentrations of DIDS. The effects of DIDS on the adenosine‐triphosphatase and P‐nitrophenyl‐phosphatase activities of isolated H,K‐ATPase were also studied and compared with those of the kinetically and structurally related Na,K‐ATPase (EC 3.6.1.37). Half‐maximal inhibition of the enzymatic activities of both enzymes were observed in the micromolar range of DIDS. The lipid bilayer of the gastric vesicle membrane is highly asymmetric and the original cytosolic side is facing the outside of the vesicle. Since DIDS does not readily cross the membrane, it is most likely that DIDS exerts its inhibitory effects by modifying the transport ATPases on their cytosolic sides.
Current status of live attenuated influenza vaccine in the United States for seasonal and pandemic influenza
Authors: Ambrose Christopher S. , Luke Catherine , Coelingh Kathleen
Published: December 2008

Abstract  A live attenuated influenza vaccine (LAIV) is currently approved in the United States for the prevention of influenza in individuals 2–49 years of age. This article summarizes the available data describing the safety and efficacy of LAIV for the prevention of influenza in both children and adults. LAIV is administered as an intranasal spray and has been shown to provide high levels of efficacy against influenza illness caused by both matched and mismatched strains in children and adults. In studies comparing LAIV and inactivated influenza vaccine in children, LAIV recipients experienced 35–53% fewer cases of culture‐confirmed influenza illness caused by antigenically matched strains. Protection through a second influenza season against antigenically matched strains has also been seen in children. In adults, definitive comparative studies of LAIV and inactivated vaccine have not been conducted and no statistically significant differences in efficacy have been demonstrated. The most common adverse reactions with LAIV include runny nose/nasal congestion in all age groups, fever >100°F in children, and sore throat in adults. Formulations of LAIV against pandemic influenza strains, including H5N1, H9N2, and H7N3, are currently being tested in preclinical and phase I clinical studies.
Cardiorespiratory fitness of asthmatic children and validation of predicted aerobic capacity
Authors: Lochte Lene , Angermann Marie , Larsson Benny
Published: December 2008

Introduction:  Predicted aerobic capacity (PAC) was estimated by submaximal exercise test and compared with monitored aerobic capacity (MAC) measured by laboratory conditions [maximal oxygen uptake (VO2peak)] in 18 children and adolescents, 10 asthmatics and 8 matched controls.

Objectives:  To compare aerobic capacity between asthmatic children and controls, to estimate the agreement between PAC and MAC and observe for trend of PAC.

Materials and Methods:  The design was prospective, 4 years (PAC) and cross‐sectional (MAC and VO2peak). Non‐parametric Wilcoxon rank sums were applied for statistical evaluation; the method of Bland and Altman estimated the agreement between PAC and MAC; P < 0.05.

Results:  PAC at baseline and follow‐up, and MAC at follow‐up, showed significant differences between groups (P < 0.05), and the mean difference between PAC and MAC at follow‐up was −1.0 mLO2/min/kg [non‐significant (ns)], indicating that PAC had a bias towards underestimation as compared with MAC. Limits of agreement, mean difference [±2 standard deviations (SD)], ranged from −8.5 to 6.5 mLO2/min/kg, indicating good agreement between the two measurements. No trend of PAC was observed (ns). Physical activity level and subjective health showed no differences between groups, or level and categories, respectively.

Conclusion:  The asthmatic participants presented with lower aerobic capacity than controls in both PAC and MAC; therefore, results confirmed the validity of the PAC method. Data warrant exploration by large‐scale paediatric asthma epidemiology.

Please cite this paper as: Lochte L, Angermann M and Larsson B. Cardiorespiratory fitness of asthmatic children and validation of predicted aerobic capacity. The Clinical Respiratory Journal 2009; 3: 42–50.
The role of peptide YY in appetite regulation and obesity
Authors: Karra Efthimia , Chandarana Keval , Batterham Rachel L.
Published: December 2008

The last decade has witnessed a marked increase in our understanding of the importance of gut hormones in the regulation of energy homeostasis. In particular, the discovery that the gut hormone peptide YY 3–36 (PYY3–36) reduced feeding in obese rodents and humans fuelled interest in the role of PYY3–36 in body weight regulation. Pharmacological and genetic approaches have revealed that the Y2‐receptor mediates the anorectic effects of PYY3–36 whilst mechanistic studies in rodents identified the hypothalamus, vagus and brainstem regions as potential sites of action. More recently, using functional brain imaging techniques in humans, PYY3–36 was found to modulate neuronal activity within hypothalamic and brainstem, and brain regions involved in reward processing. Several lines of evidence suggest that low circulating PYY concentrations predispose towards the development and or maintenance of obesity. Subjects with reduced postprandial PYY release exhibit lower satiety and circulating PYY levels that correlate negatively with markers of adiposity. In addition, mice lacking PYY are hyperphagic and become obese. Conversely, chronic PYY3–36 administration to obese rodents reduces adiposity, and transgenic mice with increased circulating PYY are resistant to diet‐induced obesity. Moreover, there is emerging evidence that PYY3–36 may partly mediate the reduced appetite and weight loss benefits observed post‐gastric bypass surgery. Taken together these findings, coupled with the retained responsiveness of obese subjects to the effects of PYY3–36, suggest that targeting the PYY system may offer a therapeutic strategy to help treat obesity.
Molecular Analysis of the Sequences Surrounding
bla
OXA-45
Reveals Acquisition of This Gene by
Pseudomonas aeruginosa
via a Novel IS
CR
Element, IS
CR5
Authors: Li Hongyang , Walsh Timothy R. , Toleman Mark A.
Published: December 2008

The
bla
OXA-45
gene of
Pseudomonas aeruginosa
07-406 is driven by a promoter found within a truncated IS
Pme
1 insertion sequence. The gene is located between nonidentical repeats of a new IS
CR
element, IS
CR5
, which is likely responsible for its acquisition. Sequence analysis indicates that IS
CR5
is a chimera of IS
CR3
and IS
CR16
.
Prevalence and Risk Factors for Selection of Quinolone-Resistant
Escherichia coli
Strains in Fecal Flora of Patients Receiving Quinolone Therapy
Authors: Yagci D. , Yoruk F. , Azap A. , Memikoglu O.
Published: December 2008

Patients taking quinolones as inpatients (
n
= 55) or outpatients (
n
= 40) and newly hospitalized patients who were not on quinolone therapy (
n
= 41) were assessed for fecal carriage of quinolone-resistant
Escherichia coli
(QREC) strains before and after therapy/hospitalization. Fluoroquinolone use in the previous 6 months was found to be a risk factor for QREC carriage before therapy/hospitalization. The prevalence of QREC strains in fecal flora increased steadily with the duration of quinolone therapy.
Deep complex morphophysiological dormancy in Sanicula europaea (Apiaceae) fits a recurring pattern of dormancy types in genera with an Arcto-Tertiary distribution
Authors: Vandelook F. , Van Assche J. A.
Published: December 2008

Genus Sanicula encompasses about 40 species, mainly from temperate deciduous forests and exhibiting an Arcto-Tertiary relict distribution. It has previously been shown that stasis in physiological traits, such as seed dormancy, can occur in genera with an Arcto-Tertiary disjunct distribution. The aim of this study was to determine the requirements for dormancy break and seed germination in the Eurasian woodland herb Sanicula europaea L. Comparing our results with other Apiaceae in a phylogenetic and biogeographic framework enables us to determine whether stasis in seed dormancy has occurred in Sanicula. Experiments under natural conditions showed that the embryo elongates within the seed during winter, when temperatures are low. Seeds of S. europaea germinated immediately after growth of the embryo was completed, and seedlings subsequently emerged when temperatures had risen in spring. A series of tests under temperature-controlled conditions revealed that growth of the embryo and physiological dormancy break occur simultaneously at low temperatures (5 °C), irrespective of a pre-treatment at high temperatures. These results contrast with the dormancy traits of several eastern North American Sanicula species, which presumably require a high temperature pre-treatment before chilling becomes effective. This geographical distribution pattern of seed dormancy traits has also been established independently in several other Arcto-Tertiary relict genera.
Trichomycetes from lentic and lotic aquatic habitats in Ontario, Canada
Authors: Strongman D. B. , White Merlin M.
Published: December 2008

Fungi and protists make up an ecological group, trichomycetes, that inhabit the guts of invertebrates, mostly aquatic insects. Trichomycetes are reported herein from arthropods collected in lotic habitats (fast flowing streams) and lentic environments (ponds, ditches, seeps, and lakes) from 11 sites in Algonquin Park and 6 other sites in Ontario, Canada. Thirty-two trichomycete species were recovered, including 7 new species: Legeriomyces algonquinensis , Legeriosimilis leptocerci , Legeriosimilis whitneyi , and Paramoebidium umbonatum are described from mayfly nymphs (Ephemeroptera); Pennella digitata and Glotzia incilis from black fly and midge larvae (Diptera), respectively; and Arundinula opeongoensis from a crayfish (Crustacea). Legeriomyces rarus Lichtw. & M.C. Williams and Stachylina penetralis Lichtw. are new North American records, and seven species are documented for the first time in Canada. More common and widely distributed trichomycete species such as Harpella melusinae Léger & Duboscq and Smittium culicis Manier, were also recovered. Most previous studies on trichomycetes have been done primarily in lotic environments but clearly lentic systems (e.g., ponds and lakes) harbour diverse arthropod communities and further exploration of these habitats will continue to increase our knowledge of trichomycete diversity.
Dark septate endophytes (DSE) of the Phialocephala fortinii s.l. – Acephala applanata species complex in tree roots: classification, population biology, and ecology
Authors: Grünig Christoph R. , Queloz Valentin , Sieber Thomas N. , Holdenrieder Ottmar
Published: December 2008

Dark septate endophytes (DSE), a diverse group of ascomycetes, are dominant root colonizers in many ecosystems. The most frequent DSE in natural forest ecosystems in the Northern hemisphere belong to the Phialocephala fortinii s.l. – Acephala applanata species complex (PAC). Recently, species rank was assigned to seven cryptic species (CSP) of P. fortinii s.l.: Phialocephala fortinii s. str. C.J.K. Wang & H.E. Wilcox, Phialocephala europaea C.R. Grünig et T.N. Sieber, Phialocephala helvetica C.R. Grünig et T.N. Sieber, Phialocephala letzii C.R. Grünig et T.N. Sieber, Phialocephala subalpina C.R. Grünig et T.N. Sieber, Phialocephala turiciensis C.R. Grünig et T.N. Sieber, and Phialocephala uotolensis C.R. Grünig et T.N. Sieber. PAC species occur on all parts of the root system of trees, from mycorrhizal root tips to the stem base. Up to 80% of fine roots in forest stands can be colonized by them, and up to eight species occur sympatrically. The present work is a mixture of review and reconsideration of published work in the light of the subdivision of P. fortinii s.l. into several species. We review the current knowledge related to taxonomy, geographical distribution, population biology, and ecology of PAC species. We identified strains of P. fortinii s.l. from previously published studies to species level. The reassessment of earlier studies indicates that PAC species behave in a versatile manner along the mutualism-parasitism continuum and lifestyle designation is complicated by the use of different experimental systems. Finally we define the most promising research areas, which will contribute to elucidate the ecological role of root endophytes in general and PAC species in particular.
Spatial variability of xylem sap flow in mature beech (Fagus sylvatica) and its diurnal dynamics in relation to microclimate
Authors: Saveyn An , Steppe Kathy , Lemeur Raoul
Published: December 2008

The spatial and diurnal variability of sap flow in a mature beech tree ( Fagus sylvatica L.) was investigated on days with different climatic conditions (sunny, cloudy, rainy), during the summer. Sap flux density (v) was measured with six heat field deformation probes placed around the stem circumference. Each probe measured v at six sapwood depths. Daily v exhibited clear radial variation, and the shape of the radial profile of v differed substantially among circumferential positions. At some positions, daily v decreased monotonically towards the stem centre, whereas at others it showed an almost monotonic increase. Hence, the conducting sapwood area of the beech was highly asymmetrical. At all positions, conducting sapwood reached beyond the deepest sampled sapwood depth, precluding correct estimations of total sap flow. The radial profile of v also differed among measuring days. A general trend was that the inner sapwood contributed relatively more to total sap flow under better weather conditions. Besides variations among days, the shape of the radial profile of v also showed within-day variations. The contribution of the inner sapwood to total sap flow increased in the afternoon, with increasing vapour pressure deficit and photosynthetic active radiation. Because of large circumferential and temporal variability, no general function for the radial profile of v could be developed.
The Taconian orogeny in southern New England: Nd-isotope evidence against addition of juvenile components
Authors: Bock B. , McLennan S. M. , Hanson G. N.
Published: December 2008

Nd-isotope data for pre-Taconian (meta)sedimentary and igneous rocks, syn-Taconian (meta)sedimentary rocks, and Late Ordovician–Silurian plutonic rocks indicate that the Ordovician Taconian orogeny did not add significant amounts of juvenile crust to the Laurentian margin in southern New England. Nd-isotope compositions of Grenvillian crust and Late Proterozoic to Early Cambrian rift sediments range from εNd of −3.1 to −6.6 at 450 Ma. Sedimentary rocks deposited during the Cambrian and the early Middle Ordovician, which represent the drift stage of Laurentia, and earliest Taconian sedimentary rocks show more negative εNd(450 Ma), with a range from −11.7 to −13.3. Sedimentary rocks deposited in response to the Taconian orogeny have uniform εNd(450 Ma) values of about −8. Middle to Late Ordovician and Permian plutonic rocks from southwestern Connecticut have εNd(450 Ma) values of −2 to −5, which indicates that these rocks contain older crustal components. Rocks with juvenile Nd characteristics are the early Paleozoic Maltby Lake Volcanics (εNd(450 Ma) +8) from southwestern Connecticut, and Middle Ordovician igneous samples from the Hawley Formation (εNd(450 Ma) +6 to −0.6) in Massachusetts.
Constraints on the timing of crustal imbrication in the central Trans-Hudson Orogen from single zircon 207Pb/206Pb ages of granitoid rocks from the Pelican thrust zone, Saskatchewan
Authors: Sun Min , Kyser Kurt , Stauffer Mel , Kerrich Rob , Lewry John
Published: December 2008

The Pelican thrust is a major ductile high-strain zone in the Reindeer Zone, Trans-Hudson Orogen, northern Saskatchewan. It is interpreted as the main sole thrust separating stacked juvenile Paleoproterozoic allochthons and underlying Archean microcontinental crust in this central part of the orogen. Exposed nonmylonitic rocks in the footwall of the thrust consist of the Sahli monzocharnockite and the smaller, more highly retrograded MacMillan Point granite. Protomylonitic to ultramylonitic gneisses in the thrust zone derive from a variety of prethrust protoliths. A footwall "internal suite" mainly comprises quartzofeldspathic orthogneisses ("Q" gneisses) and high-grade migmatitic paragneisses. Hanging-wall "external suite" mylonitic gneisses include feldspar-porphyroclastic hornblendic grey gneisses probably derived from arc plutons, and laminated amphibolites derived from volcanic rocks. The overlying allochthon mainly comprises protoliths equivalent to those of the porphyroclastic orthogneisses and laminated amphibolites, together with interfolded and overlying Paleoproterozoic paragneisses of the Kisseynew domain. The Sahli monzoeharnockite yields 207Pb/206Pb zircon and whole-rock Rb–Sr ages of ca. 2500 Ma, and the "Q" gneisses give 207Pb/206Pb zircon ages of up to ca 2900 Ma, implying that most of the internal suite (footwall) mylonite protoliths are Archean. In contrast, external suite (hanging wall) porphyroclastic orthogneisses yield ca. 1880–1840 Ma 207Pb/206Pb zircon ages. Main, peak-metamorphic displacement on the Pelican thrust is interpreted to have occurred mainly between 1840 and 1820 Ma, as indicated by 207Pb/206Pb zircon ages from small, highly deformed synthrusting granite–pegmatite neosomal bodies in the thrust zone. Undeformed postcollisional granites and pegmatites were emplaced~1789 Ma. Total duration from arc development to completion of arc–continent collision was ~100 Ma. The Pelican thrust zone may be similar in significance and style to younger, major, ocean closure related thrusts such as the Frontal Pennine thrust of the western Alps and the Main Mantle, Main Boundary, and Main Central thrusts of the Himalayas. As for the Pelican thrust, these displace oceanic rocks over older basement.
40Ar/39Ar geochronology and paleomagnetism of Independence volcano, Absaroka Volcanic Supergroup, Beartooth Mountains, Montana
Authors: Harlan Stephen S. , Snee Lawrence W. , Geissman John W.
Published: December 2008

Independence volcano is a major volcanic complex in the lower part of the Absaroka Volcanic Supergroup (AVS) of Montana and Wyoming. Recently reported Rb–Sr mineral dates from the complex give apparent ages of 91 and 84 Ma, whereas field relationships and the physical and compositional similarity of the rocks with other dated parts of the AVS indicate an Early to Middle Eocene age for eruption and deposition. To resolve the conflict between age assignments based on stratigraphic correlations and Rb–Sr dates, we report new paleomagnetic data and 40Ar/39Ar dates for Independence volcano. Paleomagnetic data for the stock and an andesite plug that cuts the stock are well grouped, of reverse polarity, and yield a virtual geomagnetic pole that is essentially identical to Late Cretaceous and Tertiary reference poles. The reverse polarity indicates that the magnetization of these rocks is probably younger than the Cretaceous normal superchron, or less than about 83.5 Ma. Hornblende from a volcanic breccia near the base of the volcanic pile gives a 40Ar/39Ar age of 51.57 Ma, whereas biotites from a dacite sill and a granodiorite stock that forms the core of the volcano give dates that range from 49.96 to 48.50 Ma. These dates record the age of eruption and intrusion of these rocks and clearly show that the age of Independence volcano is Early to Middle Eocene, consistent with stratigraphic relations. We suggest that the Rb–Sr mineral dates from the Independence stock and related intrusions are unreliable.
Soret effect on mixed convection heat and mass transfer along a semi-infinite horizontal plate in the presence of heat generation and chemical reaction
Authors: Mahmoud M A.A.
Published: December 2008

The aim of this work is to study Soret and chemical reaction effects on laminar mixed convection boundary-layer flow and heat and mass transfer past a semi-infinite horizontal flat plate in the presence of heat generation. A transformation is introduced that reduces the equations governing the flow to a system of nonlinear coupled ordinary differential equations. The transformed equations are solved numerically using the fourth-order Runge–Kutta integration scheme coupled with the shooting method. Graphical results for the velocity, temperature, and concentration profiles for various parametric conditions are presented and studied. The effects of the chemical reaction parameter, Soret parameter, and the heat generation parameter on the local skin-friction coefficient, the local Nusselt number, and the local Sherwood number are presented in tabular form and discussed.PACS Nos.: 44.20+b, 44.20+Cb
Multireference configuration interaction studies of HCBr
Authors: Burrill S , Grein F
Published: December 2008

Multireference configuration interaction (MRCI) potential curves were obtained for six 1A′, 1A′′, 3A′, and 3A′′ states of bromomethylene, HCBr, as functions of RCBr for bond angles of 102.9° and 130°, and as functions of the bond angle for RCBr = 1.8682 Å. Besides the well-known X1A′, a3A′′ and A1A′′ states, 21A′(3.26), 31A′(4.48), 41A′′(5.05), 41A′(5.06), 51A′(5.65), 43A′(6.00), 51A′′(6.60), 61A′′(6.60), 63A′′(6.61) (with estimated upper limits to the adiabatic transition energies in eV in parentheses), as well as several 5s and 6s Rydberg states, were found to be stable or metastable. Estimated spectroscopic constants for bound and metastable states, as well as vertical excitation energies for repulsive or quasi repulsive states are listed. The CH+Br dissociation energy of the ground state is about 3.5 eV, and 3.3 eV for a3A′′, whereas it is about 3.6 eV for CBr–H dissociation. It follows that photodissociation of ground-state HCBr by sunlight (up to 4.4 eV) can lead to both Br and H radicals. Photodissociation via several low-lying states is also possible. PACS Nos.: 31.10.+z, 31.15.Ar, 31.25.–v, 31.25.gf, 31.25.Qm, 31.50.Df, 31.15.Dj, 31.15.Fm
DFT studies of the σ-donor/π-acceptor properties of [SnCB10H11]– and its relationship to [SnCl3]–, CO, PF3, [SnB11H11]2–, SnC2B9H11, and related SnC2BnHn+2 compounds
Authors: Fox Mark A , Marder Todd B , Wesemann Lars
Published: December 2008

The 1,2-carbastanna-closo-dodecaborate, [SnCB10H11]–, was found via DFT calculations to have intermediate σ-donor/π-acceptor properties between those of [SnB11H11]2– and 3,1,2-SnC2B9H11, and quite similar HOMO and LUMO energies and shapes to those of [SnCl3]–, which is a stronger σ-donor and weaker π-acceptor than CO or PF3. The non-carbon containing cluster [SnB11H11]2– is shown to be a very strong donor, whereas the dicarbon cluster 3,1,2-SnC2B9H11 is a poor σ-donor but good Lewis acid, consistent with experimental results. Thus, these systems can be tuned across a very wide range via isolobal replacement of [BH]– for CH vertices. The higher negative charge in the non-carbon-containing systems, as well as the fact that boron is more electropositive than carbon, contribute to the increased energies of both HOMO and LUMO in the stannaboranes compared to the stannacarboranes, explaining their relative donor and acceptor properties.Key words: DFT calculations, tin, borane cluster.
Synthesis and electrochemical properties of bimetallic η5-indenyl ruthenium complexes
Authors: Hu Quan Yuan , Jia Guochen
Published: December 2008

Treatment of RuCl(dppm)(η5-C9H7) with alkynes HC≡C(C6H4)nC≡CH (n = 1, 2) in the presence of TlPF6 and t-BuONa affords the bimetallic ruthenium acetylide complexes [(η5-C9H7)(dppm)Ru]2(µ-C≡C(C6H4)nC≡C). Reactions of the hydride complex RuH(dppm)(η5-C9H7) with HC≡C(C6H4)nC≡CH (n = 1, 2) in refluxing toluene give the bimetallic ruthenium alkenyl complexes [(η5-C9H7)(dppm)Ru]2(µ-CH=CH(C6H4)nCH=CH). The electrochemical properties of the new complexes have been investigated by cyclic voltammetry, which reveals that the organic spacer –CH=CHC6H4CH=CH– is more effective than –C≡CC6H4C≡C– in mediating electronic communication between the two ruthenium moieties.Key words: ruthenium, bimetallic, acetylide, insertion, electrochemistry.
Synthesis, characterization, and reactivity of a novel thallium arylspiroboronate ester
Authors: Halcovitch Nathan R , Vogels Christopher M , Decken Andreas , Westcott Stephen A
Published: December 2008

Addition of 3,5-di-tert-butylcatechol (butcat) to solutions of H3B·SMe2gave the novel diboron species B2(butcat)3(2) in moderate to high yields. Compound 2 reacts with Tl(acac) to give butcatB(acac) (4) and Tl(Bbutcat2) (5). Attempts to abstract the chlorides from [(dppb)Rh(µ-Cl)]2(where dppb = 1,4-bis(diphenylphosphino)buthane) using 5 led to the unusual dimer [(dppb)Rh(µ-Cl)2(µ-Tl)Rh(dppb)][Bbutcat2] (6), which contains an unsymmetrical Rh–Tl–Rh bridge.Key words: arylspiroboronate ester, non-coordinating anion, rhodium, thallium.
Unexpectedly different reactions of [(arene)Mn(CO)3]+ cations (arene = trindane, indane, tetralin, or dibenzosuberane) with potassium t-butoxide — C-H insertions, haptotropic shifts, dimerization, or elimination
Authors: Reginato Nada , Harrington Laura E , Ortin Yannick , McGlinchey Michael J
Published: December 2008

[(η6-Trindane)Mn(CO)3][BF4] (1) reacts with tert-BuOK in THF in the presence of alkyl halides (CH2=CHCH2Br, CH3I) to yield the corresponding (η6-C15H18)Mn(CO)2X, where X = Br (3) or I (4). In contrast, 1 and tert-BuOK react, in the presence of a donor ligand, to generate (η5-C15H15)Mn(CO)2L, where L = CO (7), P(OMe)3 (8), or PPh3 (9), in which the metal has migrated from the central ring onto a peripheral ring that has lost three hydrogens; [(η6-indane)Mn(CO)3][BF4] behaves similarly. A mechanism is proposed in which the initially formed (η6-trindane)Mn(CO)2CO2-tert-Bu suffers the loss of CO2 and isobutene to yield the hydride, (η6-trindane)Mn(CO)2H, that in turn undergoes three successive C-H insertions with concomitant loss of two molecules of dihydrogen. In contrast, [(η6-tetralin)Mn(CO)3][PF6] (17) and [(η6-dibenzosuberane)Mn(CO)3][BF4] (23) each suffer deprotonation at a benzylic site. In the first case, the zwitterion formed attacks its progenitor to yield a tetralenyl-substituted (η5-cyclohexadienyl)Mn(CO)3 complex (21); however, for the dibenzosuberane complex (23) the elimination product (28) is stable. X-ray crystal structures are reported for 3, 4, 7, 8, 23, 28, and for the phosphite complexes [(η6-trindane)Mn(CO){P(OMe)3}2][BF4] (15) and [(η6-tetralin)Mn(CO)2{P(OMe)3}][PF6] (20).Key words: arene-manganese, organometallic cations, deprotonations, X-ray crystallography.
Top-down meets bottom-up — Electron-beam induced metalorganic deposition of amorphous iron oxide nanostructures
Authors: Trudel Simon , Hill Ross H
Published: December 2008

We present the use of a metalorganic precursor, iron(III) 2-ethylhexanoate, as a precursor for the electron-beam induced deposition of amorphous iron oxide nanostructures. Exposing this precursor to an area dose of 1.560 mC/cm2 with 10 keV electrons affords a material that can be developed and was determined to be amorphous iron oxide when examined by TEM, electron diffraction, and energy dispersive X-ray spectroscopy. Single point exposure yields free-standing hollow nanorods with diameters from 85 to 255 nm controlled by the exposure dose. The patterning of sub 40 nm nanowires with low (<3 nm) line edge and width roughnesses is also presented.Key words: electron beam lithography, amorphous iron oxide, nanotubes, nanowires, coordination polymer precursor.