bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photophysical Properties of a Novel Organic–Inorganic Hybrid Material: Eu(III)‐β‐Diketone Complex Covalently Bonded to SiO2/ZnO Composite Matrix
Authors: Li Ya‐Juan , Yan Bing 
Published: June 2010

AbstractIn this article, dibenzoylmethane (DBM) was first grafted with the coupling reagent 3‐(triethoxysilyl)‐propyl isocyanate (TESPIC) to form precursor DBM–Si, and ZnO quantum dot was modified with 3‐mercaptopropyltrimethoxysilane (MPS) to form SiO2/ZnO nanocomposite particle. Then the precursor DBM–Si and the terminal ligand 1,10‐phenthroline (phen) were coordinated to Eu3+ion to obtain ternary hybrid material phen–Eu–DBM–SiO2/ZnO after hydrolysis and copolycondensation between the tetraethoxysilane (TEOS), water molecules and the SiO2/ZnO network via the sol–gel process. In addition, for comparison, the binary hybrid material with SiO2/ZnO network and ternary hybrid material with pure Si–O network were also synthesized, denoted as Eu–DBM–SiO2/ZnO and phen–Eu–DBM–Si, respectively. The results reveal that hybrid material with SiO2/ZnO network phen–Eu–DBM–SiO2/ZnO exhibits the stronger red light, the longer lifetimes and higher quantum efficiency than hybrid material with pure Si–O network phen–Eu–DBM–Si, suggesting that SiO2/ZnO is a favorable host matrix for the luminescence of rare earth complexes.
Loss of nuclear receptor RXRα in epidermal keratinocytes promotes the formation of Cdk4‐activated invasive melanomas
Authors: Hyter Stephen , Bajaj Gaurav , Liang Xiaobo , Barbacid Mariano , Ganguli‐Indra Gitali , Indra Arup Kumar 
Published: June 2010

SummaryKeratinocytes contribute to melanocyte transformation by affecting their microenvironment, in part through the secretion of paracrine factors. Here we report a loss of expression of nuclear receptor RXRα in epidermal keratinocytes during human melanoma progression. In the absence of keratinocytic RXRα, in combination with mutant Cdk4, cutaneous melanoma was generated that metastasized to lymph nodes in a bigenic mouse model. Expression of several keratinocyte‐derived mitogenic growth factors (Et‐1, Hgf, Scf, α‐MSH and Fgf 2 ) was elevated in skin of bigenic mice, whereas Fas, E‐cadherin and Pten, implicated in apoptosis, cellular invasion and melanomagenesis, respectively, were downregulated within the microdissected melanocytic tumors. We demonstrated that RXRα is recruited on the proximal promoter of both Et‐1 and Hgf, possibly directly regulating their transcription in keratinocytes. These studies demonstrate the contribution of keratinocytic paracrine signaling during the cellular transformation and malignant conversion of melanocytes.
Ventilation‐perfusion relationships during graded exercise in the Standardbred trotter
Authors: NYMAN G. , BJÖRK M. , FUNKQUIST P. , PERSSON S. G. B. , WAGNER P. D. 
Published: June 2010

SummaryThe aim of this study was to evaluate pulmonary function in Standardbred trotters during graded exercise. The exercise test consisted of 4 work loads corresponding to 10%, 42%, 70% and 96% of the individual V̇O2max. Oxygen uptake was detected from an open bias flow system without valves. Cardiovascular and haemodynamic data were recorded at walk and during steady state exercise in 7 horses. Pulmonary gas exchange was assessed by conventional blood gas variables (arterial and mixed venous blood gas tensions) and the ventilation‐perfusion distribution V̇A|Q̇ as estimated by the multiple inert gas elimination technique. The dispersion of perfusion and ventilation distribution respectively (SDQ) and the difference between measured PaO2 and that predicted on the basis of amount of ventilation‐perfusion mismatching and shunt that was observed (predicted‐measured), were determined. The latter reflects mostly diffusion limitation. At the highest work load the PaCO2 increased to 50.3 torr. V̇A|Q̇ inequality increased significantly with exercise [mean log = 0.32 ± 0.03 (walk) and 0.46 ± 0.06 (heavy exercise), P < 0.01]. Alveolar‐capillary diffusion limitation of oxygen was evident at and above exercise at 70% of V̇O2max. The arterial hypoxaemia seen during the highest work load was a result of a) hypoventilation, accounting for 4%, b) increase in V̇A|Q̇ mismatch, accounting for 41% and c) considerable diffusion limitation of oxygen, accounting for 55%.
Unsteadiness of pulmonary vascular pressures in rapid acceleration supramaximal exercise
Authors: MANOHAR M. 
Published: June 2010

SummaryIn competitive racing, horses rapidly accelerate to their top speed and probably perform supramaximal work. Therefore, the primary objective of this study was to examine changes in pulmonary vascular pressures of Thoroughbreds with rapid acceleration to supramaximal exercise which could not be sustained for more than 90 s. Right atrial and pulmonary vascular pressures were studied at rest and during supramaximal exercise in 10 healthy, sound, exercise trained Thoroughbred horses. Exercise was performed on separate days without (control) and with frusemide administration 250 mg i.v., 4 h before exercise. The protocol consisted of a warm‐up at treadmill speeds of 2 to 6 m/s (trot) for 60 s each followed by 8 m/s (canter) for 60 s. Thereafter, the treadmill was raised to 10% uphill incline and speed accelerated from 8 to 15 m/s in 8 s. None of the horses could sustain exercise at 15 m/s + 10% incline for more than 90 s. Mean right atrial, pulmonary arterial, pulmonary artery wedge and pulmonary capillary pressures increased sharply as horses accelerated rapidly attaining their zenith as speed reached 15 m/s. Peak values of various pressures were maintained only for the first 45 s of exercise at 15 m/s +10% uphill incline. Thereafter, a declining trend emerged and all pressures decreased significantly as exercise duration increased. Although frusemide significantly lowered the magnitude of pulmonary vascular pressures both at rest and during exercise, it did not affect the rapid escalation in pulmonary vascular pressures upon rapid acceleration of horses or their unsteadiness in the latter 45 s of supramaximal exercise. It is suggested that rapid rate of rise of pulmonary capillary blood pressure during a sudden burst of supramaximal exercise may be a crucial factor in precipitating stress failure of pulmonary capillaries and onset of exercise induced pulmonary haemorrhage.
Variation in angular pattern adaptation from trot in hand to passage and piaffe in the Grand Prix dressage horse
Authors: HOLMSTRÖM M. , FREDRICSON I. , DREVEMO S. 
Published: June 2010

SummaryIn searching for determinants of advanced dressage performance it is of great interest to know if the angular patterns change from trot in hand to passage and piaffe occurs in approximately the same way in all horses (i.e. the variation of the angular pattern adaptation is small), irrespective of the initial pattern. In the present study trot in hand, passage and piaffe of 6 Grand Prix dressage horses were recorded by high speed film (250 frames/s). The changes in locomotion pattern from trot in hand to passage and piaffe in each horse were calculated by subtraction of the trot in hand angular measurements from the passage and piaffe angular measurements, respectively. Group mean and s.d. curves for the differences were calculated. During the whole stride the pelvic inclination showed a small variation in the difference between passage and trot in hand and during the last 20% of the stride the variation was small in the fore hoof trajectory. During the swing phase the variation of the difference between piaffe and trot in hand was small in the hind hoof trajectory. Around lift off several variables had smaller variation in passage and piaffe than in trot in hand. It was concluded that the angular pattern of the pelvic inclination may be relevant as a selection criterion for passage performance.
Effects of intravenous dextrose infusion on muscle glycogen resynthesis after intense exercise
Authors: DAVIE A. J. , EVANS D. L. , HODGSON D. R. , ROSE R. J. 
Published: June 2010

SummaryMuscle glycogen resynthesis rates were studied in 6 Standardbred geldings that were exercised on a treadmill inclined at 10% slope to deplete muscle glycogen prior to treatments. Each horse completed 15 min at 50% V̇O2max, 15 min at 70% V̇O2max, 5 min at 90% V̇O2max then rested for 30 min. This was followed by 6, 1 min sprints at 100% V̇O2max with 5 min rest periods between sprints. Muscle biopsies were taken from the middle gluteal muscle at a depth of 8 cm using the same locations in each horse. Samples were taken before, at the end of exercise and 3, 6, 9, 12 and 24 h after treatment. Blood samples were collected before exercise, immediately after exercise, then every 60 min for 8 h after treatment. Thirty min after exercise each horse was treated with either 6 g/kg dextrose i.v. as a 20% solution in an isotonic electrolyte solution at a mean (± s.e.) infusion rate of 1.67 ± 0.05 1/h, or with a solution of equivalent volume of polyionic isotonic fluid (control) at the same infusion rate. Mean pre‐exercise and post infusion peak plasma glucose concentrations were 4.9 ± 0.1 and 28.6 ± 2.8 mmol/l and 4.7 ± 0.2 and 6.0 ± 0.5 mmol/l, for treatment and control respectively. Mean pre‐exercise and peak insulin concentrations were 0.007 ± 0.002 and 0.123 ± 0.022 μu/l and 0.006 ± 0.001 and 0.012 ± 0.002 μu/l, for treatment and control respectively. There were significant effects of both time and treatment for glucose and insulin (P<0.05). Mean rates of glycogen resynthesis for the first 12 h were 14.6 ± 2.6 mmol/kg/h and 2.6 ± 3.1 mmol/kg/h respectively for treatment and control and 7.0 ± 1.6 mmol/kg/h and 3.8 ± 1.2 mmol/kg/h for the first 24 h after treatments. The administration of large doses of dextrose i.v. after exercise increases the rate of muscle glycogen resynthesis.
Distribution of lactate between red blood cells and plasma after exercise
Authors: PÖSÖ A. REETA , LAMPINEN KIMMO J. , RÄSÄNEN LEENA A. 
Published: June 2010

SummaryThe distribution of lactate between blood cells and plasma, lactate concentration in whole blood and plasma, concentration of haemoglobin and packed cell volume (PCV) were measured in Standardbred and Finnhorse trotters. Red blood cell (RBC) lactate was calculated from whole blood and plasma lactate concentrations and PCV. Plasma lactate concentration correlated positively with whole blood lactate concentration over a range of exercise intensities (r = 0.972; P < 0.001). Similarly, plasma lactate concentration correlated with the calculated RBC lactate concentration both after the standardised submaximal exercise test (SET) and races, although there was individual variation in gradients. The slope of regression after the SET increased with sampling time, but such an effect was not found after the races. The mean corpuscular haemoglobin concentration did not show any correlation with RBC lactate concentration. Based on these results, we suggest that transport of lactate to erythrocytes occurs rapidly and is mainly determined by plasma lactate concentration. The great variation between individuals and individual similarity of plasma‐cell concentration differences after submaximal and maximal exercise indicates that distribution of lactate between plasma and erythrocytes depends not only on plasma lactate concentration. Other factors, such as lactate transporter, may be important.
Effect of two types of training on sweat composition
Authors: MCCONAGHY FINOLA F. , HODGSON D. R. , EVANS D. L. , ROSE R. J. 
Published: June 2010

SummaryThe principal aim of this study was to examine whether alterations in sweat composition occurred during training. Ten Thoroughbred horses were trained 6 days per week for 9 weeks on a treadmill (+10% slope), 5 at moderate intensity, (80–100% V̇O2max) and 5 at low intensity, (40–45 % V̇O2max). On Day 1 of training and at the end of weeks 1, 2, 5 and 9, the horses performed a standardised exercise test (SET). Sweat was collected onto an absorbent pad lined with plastic and held against the skin with rubber straps. Samples were obtained from the neck and girth areas during exercise and for 10 minutes post exercise. Sweat composition during exercise (in mmol/l) was [Na+] = 143.5, [Cl−] = 181.5, [K+] = 37.5, [Ca++] = 5.1, [Mg++] = 4.2, [urea] = 5.1 and [protein] = 6.4 g/l. Training resulted in a decrease in [Ca++] of 1.6 ± 0.8 mmol/l (P < 0.05) after the first week of training. The type of training had no effect on sweat composition. Sweat produced in the post exercise period had higher [Na+], [Cl−] and [urea] than that produced during exercise. Training does not substantially alter the composition of equine sweat in response to an intense SET.
Effects of warming‐up, racing and sodium bicarbonate in Standardbred horses
Authors: FREY L. P. , KLINE K. H. , FOREMAN J. H. , BRADY A. H. , COOPER S. R. 
Published: June 2010

SummaryTwelve currently racing Standardbred horses were used to measure effects of pre‐race warm‐up exercise and racing on blood values for bicarbonate (HCO3−), pH, base excess (BE), PCO2, sodium (Na+), calcium (Ca++), chloride (Cl−) and potassium (K+). In a switchback study, 12 horses were administered NaHCO3(454 g) dissolved in 4 litres water via nasogastric tube and 12 were given 4 litres water as a control. Horses were exercised and raced in 3 groups of 4 with 2 horses in each group on each treatment. Mean durations of the 1 mile warm‐up and race were 143 and 122 s, respectively. Horses treated with NaHCOj had increased (P < 0.001) blood pH, Na+, HCO3−, PCO2and BE, while decreased (P < 0.001) K+and Ca++were found. Mean blood values for pH, HCO3−, PCO2, BE, Ca++and K+in NaHCO3treated horses, decreased (P < 0.01) after pre‐race warm‐up and racing. Blood Na+increased as a result of NaHCO3administration independent of exercise level. It is suggested that blood gas testing for the detection of illegal alkalinising agents should not be done immediately after high intensity warm‐up exercise.
Plasma carnitine concentration and uptake into muscle following oral and intravenous administration
Authors: HARRIS R. C. , FOSTER C. V. LOUISE , SNOW D. H. 
Published: June 2010

SummaryA comparison was made in 5 horses of the effects of administering 10 g L‐carnitine by i.v. injection, nasogastric feeding or addition to the feed. The systemic bioavailability (reflecting intestinal absorption and hepatic first pass elimination) of L‐carnitine administered orally was 7.1 (s.d. 5.3%). Oral administration doubled the plasma carnitine concentration after 4 h with a return to near normal levels by 12 h. Oral feeding did not increase 24 h urinary carnitine output suggesting that the plasma concentration did not exceed the renal threshold, with consequent retention in the tissues. Disappearance of plasma L‐carnitine administered i.v. followed a 2‐compartment model. The half time of disappearance was initially (t >0.5 α) 18–23 min decreasing to 115–176 min over the second phase (t >0.5 β). Administration i.v. (but not per os) resulted in a significant increase in plasma acetylcarnitine (and possibly also acylcarnitine). Eighty to 90 per cent of the administered dose was eliminated through the urine as L‐carnitine within 24 h. Continued i.v. injection of 10 g/day for 26 days did not significantly affect the total L‐carnitine content of the middle gluteal muscle in horses maintained under light exercise. The results are consistent with the normal plasma carnitine concentration in the mature well fed horse being sufficient to saturate transport into skeletal muscle and, as a result, this tissue compartment is relatively refractory to change through supplementation.
Influence of the oestrous cycle on electrolyte excretion in the mare
Authors: KINSLOW PAMELA , HARRIS PATRICIA , GRAY JULES , ALLEN W. R. 
Published: June 2010

SummaryEquine rhabdomyolysis syndrome (ERS) has been reported to occur more frequently around oestrus. Because electrolyte imbalances have been implicated in pathogenesis, this preliminary study was designed to investigate the possible influence of concentrations of reproductive hormones, progesterone and oestradiol‐17β upon the 24 h%FE values of certain electrolytes. Over a 35 day period, daily plasma progesterone concentrations were measured in 4 mature Thoroughbred mares and serum oestradiol‐17β concentrations in 3 of the mares. At various times during oestrus and dioestrus, 24 h urine collections were carried out and mean 24 h %FE values were determined, in each individual, for sodium (Na), potassium (K), chloride (CI), calcium (Ca), phosphate (PO4) and magnesium (Mg).Although the mares were maintained on a constant dietary intake of electrolytes, group mean %FE values showed cyclical trends which appeared to fluctuate in relation to the stage of the cycle. Large and relatively sudden increases in the volumetric urinary excretion of Na, Ca and Mg (mmol/24 h) were seen in samples collected during the period from 2 days preceding to 4 days following oestrus, compared to the rest of the cycle. Significant correlations were found, in one or more individual animals, between progesterone concentrations and 24 h %FE values for Na, K, Cl, Ca and PO4 and between serum oestradiol‐17β concentrations and Ca, Mg and Cl. This suggests that ovarian steroid hormones may exert an influence on urinary excretion of electrolytes in the mare. Such an influencecould be correlated, in certain individuals, to a significant effect on electrolyte status which, in turn, could potentially result in an increased risk of ERS at particular times of the oestrous cycle.
The effects of intensity and duration of training on blood lactate concentrations during and after exercise
Authors: EVANS D. L. , RAINGER JOANNE E. , HODGSON D. R. , EATON M. D. , ROSE R. J. 
Published: June 2010

SummaryThe effects of training intensity and duration on blood lactate concentrations during submaximal and after maximal treadmill exercise were investigated in 2 groups of 5 Thoroughbred horses. Horses were trained on a treadmill in either a ‘fast’ or ‘slow’ group. In the ‘fast’ group, all exercise after an initial warm‐up was at speeds which resulted in blood lactate concentrations in the range 4–8 mmol/l. In the ‘slow’ group, all training exercise was at half the speed but equal distance. Incremental speed treadmill tests were repeated after 1, 2, 3, 5, 7 and 9 weeks training. Treadmill speeds and oxygen uptake at blood lactate of 4 mmol/l (VLa4 and V̇O2‐4) and blood lactate concentration at 9 m/s (La9) were measured. Blood was also collected at 2 or 5 min intervals after a run to fatigue at 115% of maximum oxygen uptake (V̇O2max). Peak and 10 min post exercise lactate concentrations were measured, and disappearance rate (mmol/l/min) calculated. Runs to fatigue were repeated after 5 and 9 weeks of training. Data were analysed by repeated measures ANCOVA. Mean ± s.e.m. VLa4 increased from 7.0 ± 0.5 to 9.2 ± 0.2 m/s (P<0.001) and La9 decreased from 8.0 ± 1.0 to 3.9 ± 0.3 mmol/l (P<0.001) over the 9 weeks training. The pooled V̇O2‐4 increased from mean ± s.e.m. 96 ± 6.6 to 122 ± 5.6 ml/min/kg (P<0.01) after training. An increase in the pooled %V̇O2max‐4 from 79 ± 3.4% to 84 ± 2.4% after 9 weeks training was not statistically significant. There were no significant effects of training intensity on changes in VLa4, La9, or V̇O2‐4 and no significant effects of training on lactate concentrations after exercise to fatigue at 115% V̇O2max. The training induced decrease in blood lactate concentration during submaximal exercise is not dependent on intensity of exercise during training.
Effect of breathing frequency and airflow on pulmonary function in high‐intensity equine exercise
Authors: BAYLY W. M. , REDMAN M. J. , SIDES R. H. 
Published: June 2010

SummaryIt has been postulated that the hypoxaemia and hypercapnoea that characterise strenuous equine exercise are partly due to flow limitations imposed by high breathing frequencies (fb), and that gas exchange would be improved if fb could be lowered. To evaluate this possibility, 6 Thoroughbred horses underwent 4 incremental treadmill exercise tests at inclines of 0,5,10 and 25%, respectively. In the test, horses were given a warm‐up for 2 min, then ran sequentially for 1 min each at 60, 100 and 115% V̇o2max. Oxygen consumption (V̇o2), blood gas tensions (Pao2, Paco2), fb, tidal volume (VT), minute ventilation (V̇e), transpulmonary pressure (Ptp), peak inspiratory and expiratory airflows (V̇I V̇E) and work of breathing (Ẇrm) were determined during the last 15 s of exercise at each intensity. The only effect of fb on Pao2 was seen at 60% V̇o2max. Also, maximal transpulmonary pressure difference (ΔPtpmax), and peak V̇I, and V̇E on a 25% slope were lower than those recorded at the other 3 inclines at 60% V̇o2max. At 100 and 115% V̇o2max, the effect of fb was less clear. While fb still differed, the only effects of fb at 100% V̇o2max were on ΔPtpmax. At 115% V̇o2max, fb on a 25% incline was lower than that for 0 and 5% slopes. The only other difference noted at this intensity was in VT on 10% slope. However, there was no difference between VTs recorded at inclines of 0,5 or 25% at 115% V̇o2max. There was no effect of fb or exercise intensity on V̇e at 100 or 115% V̇o2max. There was no change in Pao2, fb, VT, ΔPtpmax or V̇I and V̇E as exercise intensity increased from 60–115% V̇o2max on slopes of 0,5 or 10%. However, for exercise on the 25% incline (i.e. with lower fb), each of these parameters increased (or decreased for Pao2) from 60–100%, but not from 100–115% V̇o2max. Failure of peak airflow and VT to increase when intensity increased was associated with the development of hypoxaemia and hypercapnoea, regardless of slope or fb. It is concluded that while a low fb may have some beneficial effect on gas exchange during submaximal exercise at ˜60% V̇o2max, this effect disappears as exercise intensity increases. There appear to be limits to the peak airflows that can be generated by horses during strenuous exercise, and these limits may be reached regardless of fb. Flow limitation per se may play a greater role in the development of exercise‐induced hypoxaemia and hypercapnoea in horses than does fb.
A preliminary study of the effect of inhaled nitric oxide on lung mechanics in the standing horse with histamine‐induced bronchoconstriction
Authors: SWEENEY CORINNE R. , TOMASIC M. , RUSSELL GAIL E. 
Published: June 2010

SummaryThe effect of inhaled nitric oxide on pulmonary mechanics was studied in normal standing horses with histamine‐induced bronchoconstriction. The respiratory health status of 6 normal horses was established on the basis of history, clinical and bronchoalveolar lavage examination. Intrathoracic pressures were estimated using distal oesophageal pressures. Respiratory gas flows were measured using a heated pneumotachograph. Pulmonary mechanics variables were determined from these measurements on a breath by breath basis. Bronchoconstriction was induced by nebulising a 0.75% w/v solution of histamine over 5 min. Pulmonary function was assessed during 4 periods: 1) while breathing room air prior to histamine challenge; 2) 5 min post histamine challenge; 3) 10 min post histamine challenge and while breathing 5 ppm nitric oxide; and 4) 14 min post histamine challenge while breathing room air. Statistical analysis included Friedman's nonparametric repeated measures analysis of variance followed by Dunn's multiple comparisons tests, where appropriate.Criteria for demonstration of nitric oxide effect on pulmonary mechanics variables were taken as a return of the variable value following nitric oxide administration towards control value and subsequent restoration of the value toward post histamine levels with discontinuation of nitric oxide. Five variables (dynamic compliance, airway resistance, maximum developed pressure, work of breathing, and peak expiratory flow) had significant changes in response to histamine. Three variables (dynamic compliance, airway resistance, and maximum developed pressure) met the above criteria, but only dynamic compliance and airway resistance showed statistical significance (P<.05). These results suggest that nitric oxide partly dilates small airways constricted by histamine.