bluuebunny/crossref_metadata_2025 huggingface dataset:
Differential locations in the midbrain of distinct groups of vertical eye movement‐related neurones in cat: their projections and direct connections with oculomotor neurones
Authors: SHIRAISHI Y. , NAKAO S.
Published: December 2008

The present study was undertaken to investigate the firing patterns, location and projections of vertical eye movement‐related neurones in the Forel's field H (FFH), the interstitial nucleus of Cajal (INC), and reticular formation of the mesodiencephalic junction (MDJ) in chronically prepared alert cats. A total of 456 neurones in the medial MDJ with firing closely related to vertical eye movements was examined using antidromic microstimulation and spike‐triggered averaging technique. On the basis of their firing patterns, these neurones were classified into five groups, i.e. burst neurones (BNs), burst‐tonic neurones (BTNs), tonic neurones (TNs), augmenting neurones (ANs) and pause neurones (PNs). BNs were located mainly in the dorsomedial part of the FFH. Most of TNs were found more caudally than BNs. BTNs and PNs were located further caudally, within the INC and nearby reticular formation. ANs were located mainly in the dorsolateral part of the FFH. Both medium‐lead BNs (MLBNs) and BTNs projected to the inferior rectus (IR) subdivision of the oculomotor nucleus on both sides. MLBNs projected to the trochlear nucleus as well through collateral branches of the axon projecting to the oculomotor nucleus. Downward and upward MLBNs made direct excitatory and inhibitory connections, respectively, with IR motorneurones. These results suggest that many kinds of neurones in the paramedian regions of MDJ play a significant role in the genesis of vertical eye movements.
Interaction between 17β‐oestradiol and 3α‐hydroxy‐5α‐pregnane‐20‐one in the control of neuronal excitability in slices from the CA1 hippocampus in vitro of guinea‐pigs and rats
Authors: LANDGREN S. , SELSTAM G.
Published: December 2008

The effect of 17β‐oestradiol and 3α‐hydroxy‐5α‐pregnane‐20‐one (allopregnanolone) on the action potentials in the Schaffer collateral pathway was investigated in hippocampus CA1. Slices from male and female guinea‐pigs and female rats were used. In the rat three groups were studied: (a) untreated prepubertal rats at day 25 after partus; (b) rats injected on day 26 with 10 IU of equine serum gonadotropin studied on day 28, when in the pro‐oestrus follicular phase; and (c) on day 32 when in the luteal phase. The allopregnanolone (12.6 μ.M, 0.5 nL) was applied locally in stratum oriens‐pyramidale. The 17β‐oestradiol (0.7 nM) was perfused (4 mL min‐1) or applied locally. The amplitude of the population spike in stratum pyramidale was increased by oestradiol in guinea‐pigs of both sexes and in all the three groups of rats. Allopregnanolone decreased the amplitude of the population spike in the guinea‐pigs and in the luteal phase rats. The effect appeared within seconds after the application of the drugs. The allopregnanolone inhibition of the population spike was increased by perfusion with oestradiol in the guinea‐pigs and in the luteal phase rats. This effect appeared within 7 min, and improved with increasing length of the perfusion (7–71 min). It remained for 55 min after return to perfusion with artificial cerebrospinal fluid. In prepubertal and follicular phase rats the allopregnanolone inhibition was seen only after perfusion with oestradiol for more than 15 min. The results show that 17β‐oestradiol increases the allopregnanolone inhibition and that this inhibition is most efficient during the luteal phase of the rat.
Cerebral energy metabolism during hypoxaemia. A 31P and 1H magnetic resonance study
Authors: GARDE K. , ROSTRUP E. , TOFT P. BJERRE , HENRIKSEN O.
Published: December 2008

By means of proton and phosphorous magnetic resonance spectroscopy at 1.5 Tesla the human cerebral metabolism was investigated during mild and moderate hypoxaemia. Seven volunteers participated and spectra were obtained while the subjects were breathing atmospheric air,16, 12 and 10% oxygen in N2. Pao,2, Pco2 and arterial oxygen saturation were determined during the spectroscopic measurements. Haemodynamic and respiratory mechanisms compensated the hypoxic condition and no lactate production was found. There was no change in A'‐acetyl‐aspartate. No change in intracellular pH was found. A slight but non‐significant decrease in PCr/P,‐ratio was found, indicating a decrease in the phosphorylation potential of the brain in response to hypoxaemia. The brain sustains aerobic metabolism during mild to moderate hypoxaemia.
Arachidonic acid transfer across the human red cell membrane by a specific transport system
Authors: BOJESEN I. N. , BOJESEN E.
Published: December 2008

The exchange efflux kinetics of [3H]arachidonate at 0°C, pH 7.3 from human red cell ghosts to bovine serum albumin (BSA) in buffer is analysed in terms of a closed three‐compartment model. Using albumin‐free ghosts the kinetics determines the model parameters: (1) The ratio of arachidonate bound to the inner membrane leaflet to that bound to the outer leaflet (B/E), 0.30 ± 0.03 and (2) the rate constant of unidirectional flux through the membrane from B to E (k3), 0.39 ± 0.03 s‐l. From the model parameter estimates and knowledge of apparent equilibrium constants of arachidonate binding to ghost membrane and to albumin, we estimate the dissociation rate constant of arachidonate‐albumin complex (k1) to 0.21±0.02 s‐1. The lowest rate coefficient (δ) of efflux kinetics from albumin‐filled ghosts decreases by approximately sevenfold over a 10‐fold increase in intracellular albumin. These δ‐values fit fairly well with the values predicted by the corresponding model with an unstirred intracellular compartment using the parameter values obtained in the studies with ghosts without BSA. Model parameters for arachidonate efflux are completely different from those obtained for palmitate, suggesting that different transport systems determine arachidonate and palmitate membrane transfer. The data show that binding to a limited number of specific sites is functioning as the initial and obligatory step in the transport. We propose that a protein is directly or indirectly controlling the transport capacity.
Effects of immobilization on the rat soleus muscle in relation to age
Authors: ANSVED T.
Published: December 2008

A hind limb of young adult, adult and old male Wistar rats (4–5, 6–7 and 20–21 months, respectively) was immobilized for 4 weeks by a plaster cast with the knee and ankle joints in a resting position. Enzyme‐histochemical, morphometrical and contractile characteristics of the soleus muscle were compared with those in age‐matched controls. A pronounced decrease in muscle mass and cross‐sectional muscle fibre area was found at all ages. The degree of atrophy after immobilization did not differ between different fibre types in each age group, but the decrease in fibre area was less pronounced in old animals (i.e. the fibre area was decreased by 49–64, 53–66 and 27–38% in young adult, adult and old animals, respectively). The maximum tetanus force was decreased in all age groups (by73, 78 and 69% in young adult, adult and old rats, respectively) as was the tetanus tension (i.e. tetanus force divided by muscle fibre cross‐sectional area). The contraction time of the isometric twitch was significantly altered, i.e. decreased, only in the youngest age group, although it also tended to decrease in old age. A significant increase in the number and proportion of fibre types intermediate to types I and 11 A, was found in the immobilized muscle of 4–5‐ and 6–7‐month‐old animals, but not in that of old ones (i.e. the proportion of intermediate fibres increased by14, 13 and 2% in young adult, adult and old animals, respectively). Thus, in contrast to the atrophic changes, the contractile alterations after immobilization were not markedly different between young and old age. It is further concluded that the age‐related fast‐to‐slow muscle fibre transition that occurs in normal soleus during maturation and growth can be partly reversed by restrictions of the normal muscle activity and that the ability of the soleus to modulate its fibre‐type composition in response to a change in activity may be diminished in old age.
Differential actions of exogenous and intracellular spermine on contractile activity in smooth muscle of rat portal vein
Authors: NILSSON B.‐O. , GOMEZ M. , CARRILHO R. SANTIAGO , NORDSTRÖM I. , HELLSTRAND P.
Published: December 2008

Effects of the naturally occurring polyamine spermine on electrical and contractile properties of the rat portal vein were studied. 1 mM spermine nearly abolished spike activity and spontaneous contractions and decreased the intracellular Ca2+ concentration ([Ca2+],). The phasic force responses to 0.1 and 1 μM phenylephrine were partially inhibited, but not the sustain plateau contraction caused by 5 /IM phenylephrine. The Ca2+‐force relation in high‐K+ (128 mM)‐depolarized veins was shifted to the right, EC50 for Ca2+ increasing from 0.50 ± 0.03 mM (control, n= 8) to 0.65 ± 0.06 and to 0.94 ± 0.03 at 1 (n – 4) and 10 (n = 3) mM spermine, respectively. However, at a Ca2+ concentration of 2.5 mM, giving maximal force, there was no effect of spermine (1 mM) on either force or [Ca2+],. Whereas extracellular spermine thus reduced contractile activity at moderate levels of stimulation, increased intracellular concentration of spermine potentiated the force response to Ca2+. Intracellular loading of spermine by reversible permeabilization increased its concentration by 2–3 times. The spontaneous activity and response to phenylephrine were unchanged. However, the Ca2+‐force relation of depolarized veins was shifted to the left, EC50 decreasing from 0.51 ± 0.04 mM in controls (n= 7) to 0.36 ± 0.02 mM in the loaded veins (n= 9). Spermine increased Ca2+‐activated force in portal veins permeabilized with β‐escin. The degree of potentiation was consistent with observed effects in spermine‐loaded intact veins. The results suggest that spermine at physiological intracellular concentration may contribute to the determination of Ca2+ sensitivity in vascular smooth muscle cells.
Efferent renal sympathetic nerve stimulation in vivo. Effects on regional renal haemodynamics in the Wistar rat, studied by laser‐Doppler technique
Authors: RUDENSTAM J. , BERGSTRÖM G. , TAGHIPOUR K. , GOTHBERG G. , KARLSTRÖM G.
Published: December 2008

Intrarenal blood flow regulation probably affects long‐term blood pressure homeostasis. We have previously shown that 5 Hz renal sympathetic stimulation inhibits a humoral renal depressor mechanism, otherwise activated when increasing perfusion pressure to an isolated kidney in a cross‐circulation set‐up. This inhibition was suggested to occur as a result of a reduction of renomedullary blood flow. Little is known about nervous blood flow regulation within the medulla. Therefore in this study, total renal (RBF), cortical (CBF) and papillary (PBF) blood flows were separately measured by ultrasonic and laser‐Doppler techniques in Wistar rats during graded renal sympathetic stimulations. Periods of 15 min stimulation at 0.5, 2 and 5 Hz were performed in random order. RBF decreased at 0.5 Hz by 1%, at 2 Hz by 16% (P < 0.001) and at 5 Hz by 49% (P < 0.001). In a similar fashion (r = 0.73, P < 0.001), CBF decreased by 1%, 10% (P < 0.001) and 37% (P < 0.001), respectively. By contrast, PBF increased by 2% at 0.5 Hz and 4% at 2 Hz, while it decreased at 5 Hz, by 4% (P < 0.05, compared with 2 Hz). It seems therefore, that superficial renocortical and total renal blood flows are closely regulated by renal sympathetic nerves with increasing vasoconstriction at higher frequencies, while medullary blood flow, on the other hand, seems to be under strong local control, tending to offset neurogenic flow restrictions.
Isokinetic hamstring/quadriceps strength ratio: influence from joint angular velocity, gravity correction and contraction mode
Authors: AAGAARD P. , SIMONSEN E. B. , TROLLE M. , BANGSBO J. , KLAUSEN K.
Published: December 2008

This study investigated isokinetic peak‐ and angle‐specific hamstring/quadriceps strength ratios (conventional H/Q ratio) obtained during concentric and eccentric muscle contraction and examined the influence of joint angular velocity and the effect of gravity correction on these ratios. Also, a ‘functional’ H/Q ratio was defined by calculating eccentric hamstring strength relative to concentric quadriceps strength (Heee/Qeon representative for knee extension) and calculating concentric hamstring strength relative to eccentric quadriceps strength (Heon/Qeee representative for knee flexion). The H/Q ratio was calculated based on isokinetic peak moment and 50o‐moment (0o= full extension) obtained at joint angular velocities 30, 120 and 240o s‐1. Gravity corrected conventional H/Q ratio remained constant across speeds and contraction mode, ranging from 0.47 to 0.54 and from 0.49 to 0.56 based on peak and 50o moment, respectively. In contrast, non‐corrected H/Q_ ratio increased during concentric contraction from 0.58 at 30o s‐1 to 0.74 at 240o s‐1 (P < 0.01). For knee extension at 240o s‐1 an Heee/Qeon of 1.05 (peak) and 0.89 (50o) was observed while for flexion at 240o s‐1 an Heon/Qeee of 0.27 (peak) and 0.28 (50o) was observed. In conclusion, gravity correction had high influence on the change in H/Q ratio with variation in extension velocity. A potential 1:1 hamstring/quadriceps strength relationship was demonstrated for fast knee extension, indicating a significant functional capacity of the hamstring muscles for providing muscular stability at the knee joint in such situations.
Electrically evoked torque‐velocity characteristics and isomyosin composition of the triceps surae in young and elderly men
Authors: HARRIDGE S. D. R. , WHITE M. J. , CARRINGTON C. A. , GOODMAN M. , CUMMINS P.
Published: December 2008

The electrically evoked isokinetic torque‐velocity relationship of the triceps surae of eight elderly and four non‐trained young men was examined in relation to the isomyosin composition of the soleus and the gastrocnemius muscles, determined under non‐denaturing conditions using pyrophosphate gel electrophoresis. The angle specific torque‐velocity properties of the triceps surae were measured using maximal percutaneous electrical stimulation at 50 Hz and a release technique. The elderly subjects generated significantly (P < 0.05) less absolute torque at all angular velocities when compared with the young subjects. When the isokinetic data were normalized to the isometric torque, the lower normalized torques generated by the elderly subjects were not statistically different from the young. The total fast isomyosin (FM) content of the soleus and gastrocnemius in the elderly subjects was 22 ± 13 and 35 ± 18%, respectively. This compared with 29 ± 8 (n.s.) and 44 ± 8% (n.s.) in the young subjects. When the gastrocnemius and soleus muscles were given an equal weighting and considered together to represent the whole triceps surae, the normalized torque at the fixed angular velocity of 5 rad s‐1 was significantly associated with%FM (r = 0.90, P < 0.01), and the isomyosin bands%FM1 (r = 0.90, P < 0.01) and%FM2 (r = 0.93, P < 0.001) when only the elderly subjects were considered. No relationships were observed between contractile characteristics and contractile protein profile when only the young subjects were considered. This was despite the inclusion of a further two sprint and three endurance trained athletes to increase the range of contractile characteristics and differences in muscle composition.
Effects of streptozotocin‐induced diabetes, physical training and their combination on collagen biosynthesis in rat skeletal muscle
Authors: HAN X. , KARPAKKA J. , KAINULAINEN H. , TAKALA T. E. S.
Published: December 2008

The effects of streptozotocin‐induced diabetes, physical training and their combination on the activities of prolyl 4‐hydroxylase (PH) and galactosylhydroxylysyl glucosyl‐transferase (GGT), both marker enzymes of collagen biosynthesis, and on the concentration of hydroxyproline (Hyp) were studied in vastus lateralis, rectus femoris and gastrocnemius muscles in rats. The experimental period was 12–16 weeks. Diabetes had an overall decreasing effect on specific PH activity in all muscles studied, whereas specific GGT activity remained at control level. Total PH and GGT activities decreased in all three muscles in the diabetic animals (P < 0,001). Training caused an increase in PH and GGT activities in gastrocnemius in non‐diabetic rats, whereas training in combination with diabetes did not change specific PH or GGT activity. Diabetes increased specific Hyp concentration in vastus lateralis and gastrocnemius in trained diabetic rats (P < 0.05), whereas training decreased Hyp level significantly (P < 0.05) in vastus lateralis in non‐diabetic rats, but not in diabetic animals. The results suggest that in streptozotocin‐induced diabetes the decrease in collagen synthesis rate exceeds the negative total protein balance in the muscle. Although physical training may have an increasing effect on muscular collagen synthesis in non‐diabetic rats, it is unable to prevent the decreasing effect of diabetes on collagen synthesis.
Metabolic and mechanical aspects of foot landing type, forefoot and rearfoot strike, in human running
Authors: ARDIGO' L. P. , LAFORTUNA C. , MINETTI A. E. , MOGNONI P. , SAIBENE F.
Published: December 2008

The study was undertaken to assess the metabolic and the mechanical aspects of two different foot strike patterns in running, i. e. forefoot and rearfoot striking (FFS and RFS), and to understand whether there is some advantage for a runner to use one or the other of the two landing styles. Eight subjects performed two series of runs (FFS and RFS) on a treadmill at an average speed of 2.50, 2.78, 3.06, 3.33, 3.61, 3.89, 4.17 m s‐1 Step frequency, oxygen uptake, mechanical work, and its tow components, external and internal, were measured. No differences were found for step frequency, mechanical internal work per unit time and oxygen uptake, while external and total mechanical work per unit time were significantly higher, 7–12%, for FFS. The higher external work was the result of an increase of the work performed against both gravitational and inertial forces. As the energy expenditure was the same it has been speculated that a higher storage and release of energy takes place in the elastic structures of the lower leg with FFS. In a different series of experiments on six subjects contact time, time of deceleration and time of acceleration were measured by means of a video camera while running on the treadmill at 2.50, 3.33 and 4.17 ms‐1, both FFS and RFS. Time of deceleration is similar for FFS and RFS, but contact time and time of acceleration are shorter, respectively 123 and 25%, for FFS. As the average speed is considered equal to the ratio of the distance travelled when the foot is on the ground to the contact time and this distance tends to level off at high speed, mainly for anatomical constraint, it conceivable that, beside other mechanical or metabolic factors, FFS is an obligatory choice for sprinters and middle distance runners to attain higher speed.
Effect of BQ123 on vasoconstriction as a result of either hypoxia or endothelin‐1 in perfused rat lungs
Authors: TAKEOKA M. , ISHIZAKI T. , SAKAI A. , CHANG S. W. , SHIGEMORI K. , HIGASHI T. , UEDA G.
Published: December 2008

A possible role of endothelin (ET)‐1 in mediating hypoxic pulmonary vasoconstriction (HPV) was examined by comparing haemodynamic differences between ET‐1‐induced vasoconstriction and HPV in isolated perfused rat lungs. An ETA receptor antagonist (BQ123) was also employed to assess the effects of ET‐1. The pulmonary arterial pressure (Ppa) was significantly increased by alveolar hypoxia (3% O2) and by ET‐1 (5 nM). The pulmonary microvascular pressure was not changed by hypoxia, but increased more than two‐fold by ET‐1 (P < 0.01). Hypoxia significantly increased pulmonary arterial resistance (P < 0.01) while ET‐1 significantly increased pulmonary venous resistance (P < 0.01), and slightly increased arterial resistance. Lung weight was increased by ET‐1 and decreased by hypoxia, accompanied by similar Ppa responses in both cases. BQ123 (10‐6 m and 10‐5 m) did not influence the changes in Ppa and lung weight induced by hypoxia or angiotensin II (0.3 μg). BQ123 did, however, suppress (P < 0.05) the increase in Ppa and lung weight induced by 5 nM ET‐1. Thus, it appears unlikely that ET‐1 is involved in changes in pulmonary vascular tone during acute HPV.
No effects of large doses of catecholamines on vascular permeability in isolated blood‐perfused dog lungs
Authors: SHIBAMOTO T. , WANG H.‐G , TANAKA S. , KOYAMA S.
Published: December 2008

Neurogenic pulmonary oedema (NPO) is believed to be induced by intense activation of the sympathetic nervous system, characterized by massive secretion of catecholamines into the blood stream. There is a possibility that NPO is partly the result of increased vascular permeability. However, the mechanism for an increase in pulmonary vascular permeability is not known. The present study was designed to test the hypothesis that large doses of catecholamines increase pulmonary microvascular permeability directly. Adrenaline or noradrenaline (100 and 300 pug) was injected as a bolus into isolated dog lungs perfused with heparinized autologous blood at constant pressure. Adrenaline or noradrenaline produced sustained lung weight loss although both catecholamines increased pulmonary capillary pressure, assessed by double occlusion pressure, by 2–5 mmHg above baseline. Vascular permeability, as measured by the capillary filtration coefficient and the isogravimetric capillary pressure, did not change significantly frombaseline at 30 and 60 min after catecholamine. Finally, the final‐to‐initial wet lung weight ratio of the catecholamine‐treated lungs did not differ from that of saline‐injected control lungs. Thus, we conclude that circulating catecholamines, even at supra‐physiological doses, do not increase vascular permeability in isolated blood‐perfused dog lungs.
Redistribution of body fluids during postural manipulations
Authors: MAW G. J. , MACKENZIE I. L. , TAYLOR N. A. S.
Published: December 2008

Inter‐compartmental body‐fluid distribution is contingent upon posture, exercise state and environmental temperature. This investigation aimed at quantifying the distribution of intra‐ and extravascular fluid volumes during postural manipulations. Fluid shifts were measured in eight males utilizing a simultaneous, radionuclide dilution technique, in which radioiodinated serum fibrinogen, radiochromated crythrocytes, radiobromine and tritiated water were used to measure plasma, red cell, extracellular and total body water volumes. Subjects were exposed to three postural changes [seated (control), supine and standing] for 30 min at an air temperature of 22.0 d̀C, with each posture separated by 30 min seated rest. Total body water content remained stable throughout postural changes (P= 0.842). Relative to seated volumes, BV increased by 89 mL when supine, and decreased by 406 mL while standing (P= 0.003), with such shifts being primarily a result of plasma movement (P= 0.011). Red cell volume changes were not significant. Vascular fluid lost during standing was filtered into the interstitial compartment (P= 0.014), with the extracellular and intracellular volumes remaining unaffected (P= 0.271 and P= 0.800, respectively). These observations confirmed the influence of posture on inter‐compartmental body‐fluid distribution. The intravascular fluid loss when standing was caused by the filtration of plasma into the interstitium, while, during supine rest, intravascular volume increased, reflecting fluid flux from the interstitium to the circulation.
Effect of sympathetic modualtion and sympathovagal interaction on heart rate variability in anaesthetized dogs
Authors: HEDMAN A. E. , TAHVANAINEN K. U. O. , HARTIKAINEN J. E. K. , HAKUMÄKI M. O. K.
Published: December 2008

Changes in the function of the autonomic nervous system underlying changes in heart rate variability are not fully understood. Furthermore, decreased heart rate variability has been found to be related to poor prognosis, for example, in patients with coronary artery disease. Our aim was to study how modulation in sympathetic stimulation at various frequencies is transferred into heart rate variation, and how the interaction between sympathetic and parasympathetic inputs can affect the high‐frequency component of heart rate variability. We stimulated electrically cardiac sympathetic and vagal nerves in anaesthetized, vagotomized, spinal anaesthetized dogs. We controlled the frequency and magnitude of the modulation in programmed stimulation patterns and analysed the resulting changes in heart rate variability by power spectral analysis. We found that modulations in sympathetic stimulation were reflected in the high‐frequency component of heart rate variability, as well as in the low‐ and medium‐frequency components. In addition, a novel finding was that sympathetic stimulation reduced the magnitude of the high‐frequency variations caused by vagal stimulation. This suggests that, although the high‐frequency component of heart rate variability is mainly under parasympathetic regulation, it may also be influenced by the sympathetic nervous system.
Taurine efflux is a cell volume regulatory process in proximal renal tubules from the teleost Carassius auratus
Authors: FUGELLI K. , KANLI H. , TERREROS D. A.
Published: December 2008

The potential role of taurine transport associated with volume regulation in renal tissue and isolated proximal renal tubules was studied in the teleost Carassius auratus (goldfish). The cellular taurine content in renal tissue fragments incubated in isosmotic solution (290 mOsm) (7.8 ± 0.9 (SD) μmol g wet wt‐1) decreased by 60% following exposure to hyposmotic medium (100mOsm). The rate coefficient for [14C]taurine efflux in renal tissue and in isolated proximal renal tubules was strongly stimulated following hyposmotically or urea‐activated cellular swelling. The stimulated basolateral taurine efflux pathway exhibited channel‐like functional characteristics since (a) [14C]taurine influx was stimulated in parallel with the osmolality‐dependent taurine efflux and (b) this efflux could not be stimulated by high medium taurine concentrations (40 mM) applied 10 min following the osmolality reduction (trans‐stimulation test). Administration of the 5‐lipoxygenase inhibitor ETH 615‐139 (20μM) during hyposmotic stimulation inhibited regulatory volume decreases but had no effect on taurine efflux. In addition, hyposmotically induced taurine efflux was slightly but significantly inhibited by the cyclooxygenase inhibitor indomethacin (10 μM). The taurine efflux was also dependent on both extra‐ and intracellular Ca2+. It is concluded that taurine is likely to coparticipate with KCI as an osmoeffector during RVD in Carassius proximal renal tubule cells. Cellular swelling seems to activate a basolateral taurine transport pathway with functional properties of a channel. This efflux mechanism appears to be partly regulated by Ca2+. Such a transport pathway could play a role in the cell volume regulatory mechanisms participating during transepithelial solute and water transport.
Phosphate excretion during 24 h of hypoxia in conscious rats
Authors: MIMURA Y.
Published: December 2008

The objective of this study was to investigate renal phosphate excretion during 24 h of hypoxia in conscious rats fed by total parenteral nutrition. Wistar rats weighing 190 g were exposed to hypoxia (inspired oxygen fraction = 0.10) or normoxia (inspired oxygen fraction = 0.21) for 24 h in a normobaric chamber. Renal clearance and hormonal studies were performed. The results showed a greater fractional excretion of phosphate (5.37 pL 0.07%, P < 0.05) and hypophosphataemia (7.40 pL 0.12 mg dL‐1, P < 0.01) in hypoxic rats (n = 10) than in normoxic rats (n = 13; 3.50 pL 0.37% and 8.02 pL 0.16 mg dL‐1, respectively). In addition, during hypoxia there was a significant decrease in the excretion of urinary adenosine 3′,5′‐cyclic monophosphate per glomerular filtrate (2.97 pL 1.27 nmol dL‐1, P < 0.005), a parameter of the renal action of parathyroid hormone, and a stable level of serum parathyroid hormone (10.2 pL 2.6 ng mL‐1) (cf. normoxia: 8.57 pL 0.70 nmol dL‐1 and 8.0 pL 1.7 ng mL‐1, respectively). However, creatinine clearance and the renal adenosine triphosphate level, both of which affect adenosine 3′,5′‐cyclic monophosphate excretion, were not different between the two groups. These data suggest that exposure of conscious rats to 24 h of hypoxia causes renal hyporesponsiveness to physiological levels of parathyroid hormone, which is manifested as a decrease in adenosine 3′,5′‐cyclic monophosphate excretion. Phosphaturia is not a direct net effect of hypoxia and secondary hypocapnia on renal phosphate transport, which is known to be regulated by parathyroid hormone through adenosine 3′,5′‐cyclic monophosphate.
Bioassay of gastrin using the isolated vascularly perfused rat stomach. A new, simplified and sensitive method
Authors: MÅRVIK R. , SANDVIK A. K. , WALDUM H. L.
Published: December 2008

Radioimmunoassays are sensitive and specific methods for measurement of the concentrations of regulatory peptides. However, aspects of physiological, pathophysiological and pharmacological research require knowledge about the biological activity which does not necessarily vary concomitantly with immunological activity. The present work describes a simplified bioassay for gastrin based on the gastric histamine releasing properties of this peptide, using an isolated vascularly perfused rat stomach preparation with a crystalline perfusate and a specific radioimmunoassay for histamine. The establishment of a doseresponse curve is described, as well as the utilization of the bioassay on sera from patients with hypergastrinaemia. The method is sensitive for gastrin in the low (4 pmol L‐1) picomolar range.
A re‐evaluation of the determinants of glomerular filtration rate
Authors: KARLSEN F. M. , HOLSTEIN‐RATHLOU N‐H. , LEYSSAC P. P.
Published: December 2008

Several factors are potentially able to change the glomerular filtration rate (GFR) and thereby participate in its regulation, but only a few factors seem to be physiologically important. The variable nature of proximal tubular pressure should be recognized as important in the regulation of GFR. It is argued that a distinction should be made between the terms ‘autoregulation of GFR’ and ‘regulation of GFR’ The tubuloglomerular feedback mechanism (TGF) is an important factor for autoregulatory control of GFR. When perturbation result in major increases in tubular flow, the TGF saturates, Proximal tubular pressure then increases and becomes the major factor responsible for the stabilization of GFR. Changes in the proximal reabsorption rate (APR) are important for long‐term variations in GFR (regulation of GFR). Small changes in the APR cause near paralled changes in the GFR mainly through the TGF mechanism, while larger changes in the APR cause near parallel changes in the GFR mainly because of the effect on tubular pressure. The hydraulic resistance in the distal nephro segments is an additional factor in regulating GFR, through its effect on proximal tubular pressure. The stimulus to the TGF mechanism also depresses renin release. The resulting local angiotensin II concentration has effects both on the arteriolar resistances and on the APR. The renin‐angiotensin system and TGF are therefore considered to be integrated parts of a common control system regulating GFR. According to the hypothesis advocated here, TGF‐mediated changes in afferent arteriolar resistance and angiotensin‐mediated changes in efferent arteriolar resistance and APR cooperate in counteracting perturbatins in proximal tubular pressure and Henle loop flow. However, because of the biphasic proximal effect of angiotensin II, a major unresolved question is whether physiological increases in endogenous local angiotensin II concentrations stimulate or inhibit proximal reabsorption.
Correlation between chloride flux via the mitochondria‐rich cells and transepithelial water movement in isolated frog skin (Rana esculenta)
Authors: NIELSEN R.
Published: December 2008

The coupling between net transepithelial Cl‐ influx and net water flow was investigated. Experiments were performed on isolated frog skin bathed in isotonic Cl‐ Ringer's solution in the presence of the Na+ channel blocking agent amiloride in the mucosal solution. The skins were voltage‐clamped at ‐80 or ‐ 100 mV (with the serosal solution as reference). Under these conditions the current across the skin is carried by an influx of Cl‐. In the absence of antidiuretic hormone the correlation between current and net water flow was low, but in the presence of the antidiuretic hormone, arginine vasotocin, there was a highly significant correlation between current and net water flow. The data presented here indicate that under steady state conditions about 70 molecules of water follow each Cl‐ ion across the skin. If the water influx is driven by electroosmosis one would expect that a change in current should result in an immediate change in the water flow. There was, however, a considerable time delay between the change in current and water flow. This indicates that the observed coupling between Cl‐ flux and water flow is caused by current‐induced local osmosis and not electroosmosis.
Effect of creatine supplementation on intramuscular TCr, metabolism and performance during intermittent, supramaximal exercise in humans
Authors: FEBBRAIO M. A. , FLANAGAN T. R. , SNOW R. J. , ZHAO S. , CAREY M. F.
Published: December 2008

This study examined the effect of (a) creatine supplementation on exercise metabolism and performance and (b) changes in intramuscular total creatine stores following a 5 day supplementation period and a 28 day wash‐out period. Six men performed four exercise trials, each consisting of four 1 min cycling bouts, punctuated by 1 min of rest followed by a fifth bout to fatigue, all at a workload estimated to require 115 or 125% VO2, max After three familiarization trials, one trial was conducted following a creatine monohydrate supplementation protocol (CREAT); the other after 28 d without creatine supplementation, in which the last 5 d involved placebo ingestion (CON). Intramuscular TCr was elevated (P < 0.05) in CREAT compared with the final familiarization trial (FAM3) and CON. Concentrations of this metabolite in these latter trials were not different. In addition, a main effect (P < 0.05) for treatment was observed for PCr when the data from CREAT were compared with CON. In contrast, no differences were observed in the total adenine nucleotide pool (ATP + ADP +AMP), inosine 5′‐monophosphate, ammonia, lactate or glycogen when comparing CREAT with CON. Despite the differences in TCr and PCr concentrations when comparing CREAT with other trials, no difference was observed in exercise duration in the fifth work bout. These data demonstrate that creatine supplementation results in an increase in TCr but this has no effect on performance during exercise of this nature, where the creatine kinase system is not the principal energy supplier. In addition 28 d without supplementation is a sufficient time to return intramuscular TCr stores to basal levels.
Distribution and function of nitric oxide‐containing nerves in canine corpus cavernosum and spongiosum
Authors: HEDLUND P. , LARSSON B. , ALM P. , ANDERSSON K.‐E.
Published: December 2008

Specimens of penile erectile tissue from the corpus cavernosum (CC) and corpus spongiosum (CS) of beagle dogs were investigated with reference to morphological and functional aspects of the nitric oxide (NO) system. Using immunohistochemistry, the smooth muscle bundles of the CC were found to contain a rich innervation, as seen by the pan‐neuronal marker, protein gene product 9.5. A large number of nerves also stained positively for acetylcholine esterase. There was a moderate to rich supply of nerves containing NO synthase, which was frequently co‐localized with vasoactive intestinal polypeptide. CS preparations from the proximal penis (the spongious bulb) had an innervation similar to that of the CC. However, CS preparations from the distal penis had a distinctly lower density of nerves than the proximal part, and spongious tissue from the glans penis was practically devoid of nerves. In isolated preparations of proximal and distal CC and CS, contracted by noradrenaline, electrical field stimulation (EFS) produced frequency‐dependent relaxations. The responses were less pronounced in preparations from the distal penis, particularly in the CS. Pre‐treatment with the NO‐synthesis inhibitor NG‐nitro‐L‐arginine abolished all relaxations. Carbachol effectively relaxed noradrenaline‐contracted strips. The responses were similar in proximal preparations from the CC and CS, and significantly less pronounced in strips from the distal penis. NG‐nitro‐L‐arginine significantly reduced the relaxant effect of carbachol. Preparations of spongious tissue from the glans penis did not react to high potassium solution, addition of noradrenaline, or EFS. The results demonstrate regional differences within the CS, both in innervation and functional responses.
Effects of chronic nicotine exposure on contractile enzyme‐histochemical and biochemical properties of fast‐ and slow‐twitch skeletal muscles in the rat
Authors: LARSSON L. , ÖRLANDER J. , ANSVED T. , EDSTRÖM L.
Published: December 2008

Nicotine‐exposed and control rats were compared with respect to contractile, enzyme‐histochemical and biochemical properties of fast‐ and slow‐twitch skeletal muscles in order to elucidate the mechanisms underlying previously observed effects of tobacco smoking on skeletal muscle. The nicotine was administered in drinking water, since this approach has been shown to result in a plasma nicotine pattern similar to that seen in tobacco smokers. In a pilot study, fibre‐type proportions and mitochondrial enzyme activities tended to change in the slow‐twitch soleus muscle after 9 weeks of nicotine exposure in a way similar to that previously reported in tobacco smokers. In the present study, the duration of nicotine exposure was more prolonged (18 weeks) and the number of studied animals was increased. In this series neither contractile, enzyme‐histochemical nor biochemical properties were affected by the nicotine exposure. It is thus concluded that prolonged nicotine exposure has no significant effect on the skeletal muscle characteristics studied, and that other aetiological agent(s) for the observed differences in such characteristics between smokers and non‐smokers should be searched for.
Somatostatin in the control of respiration
Authors: YAMAMOTO Y. , RUNOLD M. , PRABHAKAR N. , PANTALEO T. , LAGERCRANTZ H.
Published: December 2008

Somatostatin has been found to induce apnoea when applied into the brain ventricular system (Fuxe et al. 1982, Harfstrand et al. 1985). The site of action of somatostatin was suggested to be in the dorsal respiratory neurons in the medulla oblongata of the rat (Fuxe ef al. 1982) where high somatostatin‐like immunoreactivity has been detected (Kalia et al. 1984a). In the present study we wanted to further localize the site(s) of action of somatostatin on respiration by microinjection of somatostatin into the medulla oblongata of the cats. We could not detect any inhibitory effect of somatostatin on respiration after microinjection into the nuclear complex of the solitary tract. On the other hand microinjection of somatostatin into the region of nucleus paragiganto‐cellularis lateralis consistently caused apnoea. This finding further supports the idea that this structure functions as an integrative area of respiratory drive inputs.
Larvicidal potentials of leaf and bark extracts of Eucalyptus camaldulensis (Schlect) and Eucalyptus citriodora (Hook) on Culex quinquefasciatus (Say) larvae
Authors: IDRIS H. S. , LAWAL S. B. , BALARABE B. M.
Published: December 2008

The larvicidal activity of leaf and bark extracts of Eucalyptus camaldulensis and Eucalyptus citriodora on juveniles of Culex quinquefasciatus was determined. Larvae were successfully bred in the laboratory to obtain a “pure” colony. One hundred and sixty‐two batches of 25 larvae each were treated with 3.90, 15.63, 62.50, 250 and 1000 mg/L of plant extract in three replicates, for 24 h to record mortality and for up to 96 h to record feeding and fecundity. There was an increase in percentage mortality with increase in concentration of the petroleum ether plant extracts. There was a statistically significant difference (P < 0.05) between extracts used in the bioassay and mortality of larvae, but there was no significant difference (P > 0.05) between the two plant species. Statistical analysis of average mortality figures using Probit analysis for the leaf extracts of E. citriodora and E. camaldulensis, respectively, had LC50 of 245.47 (26.89 ± 10.13 [SE]) and 316.23 (22.89 ± 8.95) for the crude extracts; 97.72 (44.95 ± 12.89) and 223.87 (29.17 ± 9.56) for the petroleum ether extracts; and 162.18 (30.7 ± 11.16) and 257.04 (26.47 ± 9.28) for the methanol extracts. The bark extracts of E. citriodora and E. camaldulensis, respectively, had LC50 of 251.19 (27.78 ± 8.39) and 398.11 (20.7 ± 7.17) for methanol; and 302.0 (21.56 ± 8.11) and 630.96 (13.56 ± 6.4) for hexane. Both plant species showed anti‐feeding properties against larvae of Culex quinquefasciatus.
Reproductive responses to photoperiod and temperature by artificially hibernated bumblebee (Bombus terrestris) queens
Authors: AMIN Md. Ruhul , SUH Sang Jae , KWON Yong Jung
Published: December 2008

Post‐hibernated bumblebee (Bombus terrestris) queens were kept for 1 week under photoperiodic conditions of 8 h light : 16 h dark, and at four different temperatures (24, 28, 32 and 36°C). The reproductive performance of the queens was then observed. It was found that exposure temperature and hibernation duration did not affect the oviposition rate. The pre‐oviposition period was found to be shortest (3.8 ± 0.7 days) for queens that had hibernated for 4.0 months and had been activated at 28°C. Timing of the initiation of the switch‐point was not affected by exposure temperature and hibernation duration. Significantly higher numbers of workers (268.0 ± 31.4) and sexual queens (119.3 ± 16.8) were produced by the queens that had hibernated for 3.0 months and had been activated at 28 and 36°C, respectively. The queens that had hibernated for 4.0 months and had been activated at 36°C produced the highest number of males (296.2 ± 32.3).
Correlation between population dynamics of mosquito larvae and their habitat qualities
Authors: RANJEETA Lalit Mohan , SHARMA Preeti , SRIVASTAVA C. N.
Published: December 2008

Surveillance of anopheline and culicine larvae was conducted fortnightly to determine population composition and density at seven sites in the area of the Mathura Refinery, Mathura, India during 2005–2006. The correlation between population of the vectors and their habitat quality was established. Temperature (0.978 and 0.85°C), pH (0.99 and 0.95), conductivity (0.98 and 0.98 mho) and calcium ion hardness (0.978 and 0.85 p.p.m.) were positively correlated with the populations of both larval species. In contrast, the correlation coefficients between the parameters total hardness, magnesium ion hardness, biochemical oxygen demand and chemical oxygen demand varied with the larval species. The anopheline larval population was dominant over the culicine population in the surveillance area. The distribution of anopheline mosquito larvae during the study period was found to be constant, and the average density of anopheline and culicine larvae was 84.70 and 15.30%, respectively, across all seven sites. Thus, the study demonstrated spatial and temporal population differences of mosquito larvae with respect to environmental factors, including water quality.
Evaluation of damage caused by stalk borers, Sesamia spp. (Lepidoptera: Noctuidae), on sugarcane quality in Iran
Authors: ASKARIANZADEH Alireza , MOHARRAMIPOUR Saeed , KAMALI Karim , FATHIPOUR Yaghub
Published: December 2008

The noctuid stalk borers, Sesamia spp. (S. cretica Led. and S. nonagrioides Lef.), damage a considerable percentage of sugarcane internodes annually in the province of Khuzestan, Iran. A study was conducted to quantify the relationship between stalk borer damage and sugar quality to estimate the monetary loss incurred at these levels of damage at harvest time. Three commercial varieties of sugarcane (SP70‐1143, CP69‐1062 and CP48‐103) were studied to determine the effects of damage on sugar quality. Stalks were separated into seven groups: control (without damage); one to five bored internodes per stalk; and more than five bored internodes per stalk. The percentage of bored internodes and several parameters, such as pol and brix, were measured. Sugar in the control group was 123.78, 123.72 and 104.84 kg/ton for SP70‐1143, CP69‐1062 and CP48‐103, respectively. Sugar per ton, juice purity, pol and brix were all significantly inversely correlated to the percentage of bored internodes. Estimated sugar losses for every 1% bored internode were 0.17, 0.39 and 0.23% (equal to 210, 482 and 241 kg sugar) in SP70‐1143, CP69‐1062 and CP48–103, respectively. These varieties could tolerate damage of up to 18.1, 11.7 and 18.9% bored internodes, respectively, compared to the control. Regression slopes for CP69‐1062 were slightly higher than those of the other two varieties. Therefore, based on quality damage, CP69‐1062 is susceptible to stalk borer damage.
Fidelity of Hymenoptera and Diptera pollinators in onion (Allium cepa L.) pollination
Authors: SAEED Shafqat , SAJJAD Asif , KWON Ohseok , KWON Yong Jung
Published: December 2008

Onion (Allium cepa L.) is protandrous in nature and requires cross‐pollination to avoid inbreeding. The pollination potential of native bees (Hymenoptera) and true flies (Diptera) was assessed in the perspective of finding the best pollinators for onion cross‐pollination and seed multiplication. The community of pollinators was composed of four bee species and twelve true fly species. Episyrphus balteatus, Eupeodes sp., Musca domestica and Eristalinus aeneus were the most abundant pollinators. The maximum pollinator activity was observed from 12 to 24 days after opening of the flowers. The pollination effectiveness of tested bees (Apis dorsata and Apis florea) was greater than true flies (E. balteatus, Eupeodes sp., M. domestica, E. aeneus and Callihoridae sp.) in terms of Spears values.
Two quediine species (Coleoptera: Staphylinidae: Staphylininae) new to Korea
Authors: CHO Young Bok , AHN Kee‐Jeong
Published: December 2008

Two quediine species (Quedius samuraicus Bernhauer and Schubert, and Velleius elongatus Naomi) were identified for the first time in Korea. Diagnoses and illustrations of the habitus and male genitalia are presented.
FluBlok, a recombinant hemagglutinin influenza vaccine
Authors: Cox Manon M.J. , Patriarca Peter A. , Treanor John
Published: December 2008

Abstract  FluBlok, a recombinant trivalent hemagglutinin (HA) vaccine produced in insect cell culture using the baculovirus expression system, provides an attractive alternative to the current egg‐based trivalent inactivated influenza vaccine (TIV) manufacturing process. FluBlok contains three times more HA than TIV and does not contain egg‐protein or preservatives. This review discusses the four main clinical studies that were used to support licensure of FluBlok under the ‘Accelerated Approval’ mechanism in the United States.