bluuebunny/crossref_metadata_2025 huggingface dataset:
Re-evaluation of the second thermodynamic dissociation constants of α-alanine, valine, and leucine using potentiometric data measured for aqueous potassium chloride solutions at 298.15 K
Authors: Partanen Jaakko I , Juusola Pekka M , Verraes Virginie
Published: February 2005

Equations were developed for the calculation of the second stoichiometric (molality scale) dissociation constants (Km2) of α-alanine, valine, and leucine in aq. KCl solutions at 298.15 K from the revised thermodynamic dissociation constants (Ka2) of these acids and the ionic strength (Im) of the solutions. The ionic strength of the solutions considered in this study is determined mostly by KCl alone, and the equations for Km2were based on the single-ion activity coefficient equations of the Hückel type. The existing literature data obtained from Harned cell measurements and new potentiometric titration data were used to revise the Ka2values of the three amino acids. The values (1.295 ± 0.013) × 1010, (1.894 ± 0.009) × 1010, and (1.685 ± 0.011) × 1010were obtained from the new potentiometric titration data for α-alanine, valine, and leucine, respectively. For alanine and valine, the new Ka2values are also supported by the Harned cell data used, but the value (1.80 ± 0.02) × 1010obtained for leucine from these data is significantly different. The potentiometric values are recommended here. The activity coefficient equations for the calculation of Km2values were also determined from the new potentiometric data. By means of the activity coefficient equations obtained for these three amino acids for KCl solutions, Km2can be evaluated almost within experimental error up to an Imof about 1.0 mol kg1. The Km2values calculated by this method are also compared with the values suggested in the literature.Key words: ionic strength dependence, stoichiometric dissociation constant, Debye-Hückel equation, potentiometry, α-alanine, valine, leucine.
Effects of precommercial thinning on snowshoe hare habitat use during winter in low-elevation montane forests
Authors: Ausband David E , Baty G Ross
Published: February 2005

We assessed snowshoe hare (Lepus americanus L.) habitat use during winter on two precommercial thinning treatments in sapling stands in northwestern Montana, USA. One treatment type retained 0.2-ha patches of unthinned saplings, representing 8% of the total stand area, and the second retained 0.8-ha patches of unthinned saplings, representing 35% of the stand area. Snowshoe hare habitat use was also estimated within a nearby control sapling stand and mature conifer stands. We used snow tracking and fecal pellet counts to estimate use before and after thinning treatments were applied. Although we did not find a conclusive trend in hare use of sapling stands after thinning, use within the control stand and adjacent mature stands suggested there was considerable movement of hares to nearby untreated stands after thinning. Hares used retention patches regardless of size, even though large retention patches were four times larger than small retention patches. Because hares demonstrated an affinity for dense patches of residual forest, any retention of untreated saplings may be beneficial for hares during winter when applying precommercial thinning treatments in areas where stand sizes are relatively small (1014 ha), and the resulting thinned matrix is less harsh than in larger thinned stands. Use within thinned portions of the stand and unthinned remnant blocks suggests that over the winter hares may also benefit from a connectivity of dense cover.
Triterpenes in elms in Spain
Authors: Martín-Benito Dario , García-Vallejo Maria Concepción , Pajares Juan Alberto , López David
Published: February 2005

Diethyl ether-petroleum ether extracts were prepared from 49 samples of bark from four elm species (Ulmus glabra Hudson, Ulmus laevis Pall, Ulmus minor Miller, and Ulmus pumila L.) and hybrids from crosses between three of these species. Chemical analyses were performed by gas chromatography  mass spectrometry. Ten triterpenes and three sterols were identified. These compounds are discussed in terms of chemotaxonomy of the genus and identification of hybrids, and in relation to the differential attractivity for elm bark beetle feeding. Separation of the four pure species was successfully achieved by the use of the multivariate discriminant analysis. Ulmus minor × U. pumila hybrids were clearly segregated from their parental species, while U. minor × U. glabra trees were misclassified as U. minor by a multivariate discriminant analysis. Three compounds are described for the first time in the family Ulmaceae and two more in the genus Ulmus. Some of the triterpenes and sterols isolated only in U. glabra and U. laevis may be responsible for the deterrence of bark beetles to feed on these least preferred species.
Diabetic cardiomyopathy: recent evidence from mouse models of type 1 and type 2 diabetes
Authors: Severson David L
Published: February 2005

Diabetic cardiomyopathy is defined as ventricular dysfunction of the diabetic heart in the absence of coronary artery disease. With the use of both in vivo and ex vivo techniques to assess cardiac phenotype, reduced contractile performance can be observed in experiments with mouse models of both type 1 (insulin-deficient) and type 2 (insulin-resistant) diabetes. Both systolic dysfunction (reduced left ventricular pressures and decreased cardiac output) and diastolic dysfunction (impaired relaxation) is observed in diabetic hearts, along with enhanced susceptibility to ischemic injury. Metabolism is also altered in diabetic mouse hearts: glucose utilization is reduced and fatty acid utilization is increased. The use of geneticallyengineered mice has provided a powerful experimental approach to test mechanisms that may be responsible for the deleterious effects of diabetes on cardiac function.Key words: cardiac function, cardiac metabolism, cardiac phenotype.
Vanadium and the cardiovascular functions
Authors: Coderre Lise , Srivastava Ashok K
Published: February 2005

Inorganic and organic compounds of vanadium have been shown to exhibit a large range of insulinomimetic effects in the cardiovascular system, including stimulation of glucose transporter 4 (GLUT-4) translocation and glucose transport in adult cardiomyocytes. Furthermore, administration of vanadium compounds improves cardiac performance and smooth muscle contractility, and modulates blood pressure in various models of hypertension and insulin resistance. Vanadium compounds are potent inhibitors of protein tyrosine phosphatases. As a result, they promote an increase in protein tyrosine phosphorylation of several key components of the insulin signaling pathway, leading to the upregulation of phosphatidylinositol 3-kinase and protein kinase B, two enzymes involved in mediating GLUT-4 trans location and glucose transport. In addition, vanadium has also been shown to activate p38 mitogen-activated protein kinase and increase Ca2+levels in several cell types. The ability of vanadium compounds to activate these signaling events may be responsible for their ability to modulate cardiovascular functions.Key words: vanadium compounds, glucose transport, smooth muscle contractility, insulin signaling pathway.
The relaxant effect of nociceptin on porcine coronary arterial ring segments
Authors: Xu Pei-Han , Chang Ming , Cheng Li-Xiang , Cheng Qiang , Yan Xiang , Wang Rui
Published: February 2005

Nociceptin (NC), alias orphanin FQ, has been identified as the endogenous ligand of the opioid receptor-like 1 receptor (ORL1). The purpose of this study was to assess the effect of nociceptin on porcine coronary arteries and to investigate the mechanism of its action, if any. Rings of coronary arteries from porcine hearts were suspended in baths containing Krebs solution, and isometric tension was measured. The response to nociceptin (10–12–10–5 mol/L) was investigated in porcine coronary arterial rings and also in such rings contracted with prostaglandin F2α (PGF2α). The effects of endothelium, nitroxide (NO), methylene blue, cyclic GMP (cGMP), naloxone, [Nphe1]NC(1–13)NH2, and propranolol on nociceptin-induced relaxation were also assessed. Our study showed nociceptin relaxed the porcine coronary arterial rings and inhibited the vasocontractivity to PGF2α. The relaxing response of nociceptin in coronary arteries was significantly reduced by removal of endothelium and by the presence of L-NNA, cGMP, and [Nphe1]NC(1–13)NH2, the selective nociceptin receptor antagonist, but not by naloxone, the nonselestive opioid receptor blocker or propranolol, which blocks the adrenergic β-receptor. Our results suggest that nociceptin induces relaxation of isolated coronary artery through NO, cGMP, and ORL1.Key words: nociceptin, porcine coronary artery, NO, ORL1.
"Vulnerable plaques" — ticking of the time bomb
Authors: Mitra Amit K , Dhume Ashwini S , Agrawal Devendra K
Published: February 2005

Atherosclerosis and its sequelae are one of the leading causes of morbidity and mortality, especially in the developed nations. Over the years, treatment protocols have changed with the changing understanding of the disease process. Inflammatory mechanisms have emerged as key players in the formation of the atherosclerotic plaque. For the majority of its life span, the plaque develops silently and only some exhibit overt clinical manifestations. The purpose of this review is to examine the inherent properties of some of these "vulnerable" or symptomatic plaques. Rupture of the plaque is related to the thickness of the fibrous cap overlying the necrotic lipid core. A thin cap is more likely to lead to rupture. Multiple factors broadly grouped as the "determinants of vulnerability" are responsible for directly or indirectly influencing the plaque dynamics. Apoptosis is considered an important underlying mechanism that contributes to plaque instability. Inflammatory reactions within the plaque trigger apoptosis by cell–cell contact and intra cellular death signaling. Once started, the apoptotic process affects all of the components that make up the plaque, including vascular smooth muscle cells, endothelial cells, and macrophages. Extensive research has identified many of the key cellular and molecular regulators that play a part in apoptosis within the atherosclerotic lesion. This information will help us to gain a better understanding of the underlying mechanisms at the cellular and molecular level and enable us to formulate better therapeutic strategies to combat this disease.Key words: apoptosis, atherosclerosis, inflammation, plaque stability, vulnerable plaques.
Application of high-dose propofol during ischemia improves postischemic function of rat hearts: effects on tissue antioxidant capacity
Authors: Xia Zhengyuan , Godin David V , Ansley David M
Published: February 2005

Previous studies have shown that reactive oxygen species mediated lipid peroxidation in patients undergoing cardiac surgery occurs primarily during cardiopulmonary bypass. We examined whether application of a high concentration of propofol during ischemia could effectively enhance postischemic myocardial functional recovery in the setting of global ischemia and reperfusion in an isolated heart preparation. Hearts were subjected to 40 min of global ischemia followed by 90 min of reperfusion. During ischemia, propofol (12 µg/mL in saline) was perfused through the aorta at 60 µL/min. We found that application of high-concentration propofol during ischemia combined with low-concentration propofol (1.2 µg/mL) administered before ischemia and during reperfusion significantly improved postischemic myocardial functional recovery without depressing cardiac mechanics before ischemia, as is seen when high-concentration propofol was applied prior to ischemia and during reperfusion. The functional enhancement is associated with increased heart tissue antioxidant capacity and reduced lipid peroxidation. We conclude that high-concentration propofol application during ischemia could be a potential therapeutic and anesthetic strategy for patients with preexisting myocardial dysfunction.Key words: propofol, ischemia, heart, rat, oxidative stress.
Doxazosin-induced up-regulation of α1A-adrenoceptor mRNA in the rat lower urinary tract
Authors: Yono Makoto , Foster, Jr. Harris E , Shin David , Takahashi Wataru , Pouresmail Mehdi , Latifpour Jamshid
Published: February 2005

α1-adrenoceptor (AR) antagonists can provide effective treatment of symptoms caused by benign prostatic hyperplasia. However, their mechanisms of action have not been fully elucidated. We previously reported that chronic administration of doxazosin causes an up-regulation in the mRNA expression of all three α1-AR subtypes in the rat prostate. As α1-AR antagonists might also affect the properties of α1-ARs in the lower urinary tract, we examined the effects of doxazosin (2 or 4 mg/kg daily subcutaneously, supplemented with 4 mg/kg daily orally for 8 or 12 weeks) on α1-AR subtype mRNAs in the rat bladder dome, bladder base, and urethra using real-time reverse transcription PCR. Rats that received the highest doses of doxazosin had significantly heavier bladder base and prostatic urethra than controls. PCR data showed that all three α1-AR subtypes were expressed in all tissues studied. Doxazosin treatment caused an up-regulation in the mRNA levels of α1A-AR in the rat bladder base and prostatic urethra, indicating that chronic doxazosin treatment may cause an alteration in the properties of α1A-AR subtype mRNA in these two areas. Furthermore, the heavier bladder base and prostatic urethra in the doxazosin-treated rats suggest that α1-AR antagonist treatment might also influence the growth process in these areas of the rat lower urinary tract.Key words: α1-adrenoceptor, doxazosin, bladder, urethra.
Cardiac transplantation and resistance artery myogenic tone
Authors: Moien-Afshari Farzad , Skarsgard Peter L , McManus Bruce M , Laher Ismail
Published: February 2005

Transplantation is an effective treatment for end-stage heart disease; however, most grafts eventually fail by progressive cardiac failure. Primarily, failure is ischemic due to the occlusive nature of transplant vascular disease (TVD). Early after transplantation and preceding TVD, alterations in coronary physiology such as reduced vascular myogenic tone occur. Resistance arteries possess an inherent ability to constrict in response to transmural pressure; this constrictive response (myogenic tone) is important in fluid homeostasis. Recent evidence suggests that a decline in myogenic tone leads to deficits in cardiac contractility. Factors that reduce myogenic tone in transplantation include constitutive nitric oxide synthase and inducible nitric oxide synthase catalyzed, NO-mediated vasodilation as well as deficits in arterial contractile function. Reduced myogenic tone in allograft resistance arteries increases coronary blood flow such that hydrostatic pressure surpasses oncotic pressure, causing cardiac interstitial edema. This generalized edema decreases ventricular compliance leading to heart failure during the course of acute immune rejection of the graft. Cyclosporine A treatment reduces immune mediated dysregulation of myogenic tone, resulting in reduced interstitial edema and improved cardiac function. In this review, we discuss aspects of TVD and myogenic tone signaling mechanisms and how aberrations in myogenic regulation of arterial tone contribute to functional changes observed in cardiac transplant.Key words: myogenic tone, smooth muscle, nitric oxide, transplantation, edema.
Effects of cyclic GMP and its protein kinase on the contraction of ventricular myocytes from hearts after cardiopulmonary arrest
Authors: Su Jun , Scholz Peter M , Tse James , Weiss Harvey R
Published: February 2005

Hearts undergoing cardiopulmonary arrest and resuscitation have depressed function and may have changes in signal transduction. We hypothesized that the cyclic GMP (cGMP) signaling pathway would be altered in the post-resuscitation heart. This was studied in ventricular myocytes from 7 anesthetized open-chest rabbits. Cardiopulmonary arrest was achieved for 10 min through ventricular fibrillation and respirator shutdown. After cardiopulmonary arrest, respiration was resumed, the heart was defibrillated, and the heart recovered for 15 min. Seven additional rabbits served as controls. Myocyte function was measured via a video edge detector. Myocytes were treated with 8-bromo-cGMP (10–5–10–6mol/L) followed by KT5823 (10–6mol/L, cGMP protein kinase inhibitor). The baseline percent shortening was significantly depressed in the cardiac arrest myocytes compared with control (3.3 ± 0.1 vs. 5.5 ± 0.3%). Treatment with 8-Br-cGMP similarly and dose-dependently reduced cell contraction in both cardiac arrest (–24%) and control (–25%) myocytes. The negative effect of 8-Br-cGMP was partially reversed by KT5823 in control myocytes, but not in the arrest group, indicating reduced involvement of cGMP protein kinase. Multiple proteins were specifically phosphorylated when cGMP was present, but the degree of phosphorylation was significantly less in myocytes after cardiac arrest. The data suggested that the basal contraction was reduced, but the functional response to 8-Br-cGMP was preserved in myocytes from cardiopulmonary arrested hearts. The results also indicated that the action of cGMP appeared to be mainly through non-cGMP protein kinase pathways in the post-resuscitation heart.Key words: myocardial ischemia and reperfusion, myocyte function, cyclic GMP, cyclic GMP protein kinase, rabbit.
Receptors subtypes involved in adenosine-mediated modulation of norepinephrine release from cardiac nerve terminals
Authors: Lorbar Mojca , Chung Eugene S , Nabi Arash , Skalova Katarina , Fenton Richard A , Dobson, Jr. James G , Meyer Theo E
Published: February 2005

The objective of this study was to determine which adenosine receptor subtypes were involved in the modulation of norepinephrine release from cardiac nerve terminals. In addition, the persistence of adenosine-mediated effects was evaluated. Rat hearts attached to the stellate ganglion were isolated and perfused. The ganglion was electrically stimulated twice (S1 and S2), allowing 10 min between the stimulations. To determine adenosine receptor subtypes, selective and nonselective adenosine agonists and antagonists were infused following S1 and until the end of S2. To evaluate the persistence of adenosine-mediated effect on norepinephrine release, the stellate ganglion was stimulated a third (S3) and fourth (S4) time. Coronary effluents were collected to determine norepinephrine content. Adenosine and a selective A1 receptor agonist, CCPA, inhibited norepinephrine release by 49% and 54%, respectively. This effect was reversed by simultaneous infusion of nonspecific (8-SPT) and specific (DPCPX) A1 receptor antagonists. Selective A2A (CGS 21680) and A3 (AB-MECA) receptor agonists had no discernible effect on norepinephrine release. Similarly, adenosine A2A receptor antagonists CSC and DMPX did not alter the dose-response relation between norepinephrine release and adenosine. Finally, the inhibitory effects of adenosine on norepinephrine release did not persist 10 min subsequent to the removal of adenosine. Adenosine inhibited norepinephrine release primarily via the adenosine A1 receptor. This effect of adenosine was of short duration. Adenosine A2A and A3 receptors were either absent or functionally insignificant in the regulation of norepinephrine release in the rat heart.Key words: adenosine, norepinephrine, receptor, rat, neurotransmitters.
Percent relative cumulative frequency analysis in indirect calorimetry: application to studies of transgenic mice
Authors: Riachi Marc , Himms-Hagen Jean , Harper Mary-Ellen
Published: February 2005

Indirect calorimetry is commonly used in research and clinical settings to assess characteristics of energy expenditure. Respiration chambers in indirect calorimetry allow measurements over long periods of time (e.g., hours to days) and thus the collection of large sets of data. Current methods of data analysis usually involve the extraction of only a selected small proportion of data, most commonly the data that reflects resting metabolic rate. Here, we describe a simple quantitative approach for the analysis of large data sets that is capable of detecting small differences in energy metabolism. We refer to it as the percent relative cumulative frequency (PRCF) approach and have applied it to the study of uncoupling protein-1 (UCP1) deficient and control mice. The approach involves sorting data in ascending order, calculating their cumulative frequency, and expressing the frequencies in the form of percentile curves. Results demonstrate the sensitivity of the PRCF approach for analyses of oxygen consumption ([Formula: see text]02) as well as respiratory exchange ratio data. Statistical comparisons of PRCF curves are based on the 50th percentile values and curve slopes (H values). The application of the PRCF approach revealed that energy expenditure in UCP1-deficient mice housed and studied at room temperature (24 °C) is on average 10% lower (p < 0.0001) than in littermate controls. The gradual acclimation of mice to 12 °C caused a near-doubling of [Formula: see text] in both UCP1-deficient and control mice. At this lower environmental temperature, there were no differences in [Formula: see text] between groups. The latter is likely due to augmented shivering thermogenesis in UCP1-deficient mice compared with controls. With the increased availability of murine models of metabolic disease, indirect calorimetry is increasingly used, and the PRCF approach provides a novel and powerful means for data analysis.Key words: thermogenesis, oxygen consumption, metabolic rate, uncoupling protein, UCP.
Level of ventilation influences the cardiovascular response to hypoxemia in lambs
Authors: Fewell James E , Taylor Bonnie J
Published: February 2005

Newborn animals of a number of species display a brisk increase in ventilation followed by a gradual drop toward or below baseline within minutes of exposure to acute hypoxemia. Heart rate and cardiac output (a determinant of systemic oxygen transport along with the arterial oxygen content) appear to follow a similar pattern, but whether or not the cardiovascular response is influenced by the respiratory response is unknown. We therefore carried out experiments in which the level of ventilation was controlled during normoxemia and hypoxemia to test the hypothesis that the level of ventilation influences the cardiovascular response to acute hypoxemia. Six lambs ranging in age from 17 to 22 days were anesthetized, tracheostomized, and instrumented for measurement of cardiovascular variables. A recovery period of at least 3 days was allowed before the study when each lamb was artificially ventilated with a mixture of 70% nitrous oxide and 30% oxygen in nitrogen. A control respiratory frequency (f) of 30 breaths per min was set and a control tidal volume (VT) was chosen to achieve normocapnia. Cardiovascular measurements were made during normoxemia and hypoxemia (FIO2 0.10) 5 min after f or VT was changed to simulate a decrease, no change, or an increase in ventilation. During normoxemia, the level of ventilation had little effect on the measured cardiovascular variables. At control levels of ventilation, hypoxemia caused an increase in cardiac output that was due solely to an increase in stroke volume as heart rate decreased; blood pressure was unchanged. Increasing ventilation during hypo xemia did not augment cardiac output or alter blood pressure as compared with that observed at control levels of ventilation. Decreasing ventilation during hypoxemia, however, decreased cardiac output due to a profound bradycardia; blood pressure increased significantly. Our data provide evidence that the level of ventilation significantly influences the cardiovascular response to hypoxemia in young lambs.Key words: newborn, hypoxemia, cardiovascular, respiration, systemic oxygen transport.
Why are there so many empty lakes? Food limits survival of mallard ducklings
Authors: Gunnarsson Gunnar , Elmberg Johan , Sjöberg Kjell , Pöysä Hannu , Nummi Petri
Published: February 2005

Food is an important factor affecting survival in many bird species, but this relationship has rarely been explored experimentally with respect to reproductive output of precocial birds. In a field experiment we tested the hypothesis that food abundance limits reproductive output in breeding dabbling ducks. Onto 10 oligotrophic lakes in northern Sweden we introduced one wing-clipped female mallard (Anas platyrhynchos L., 1758) and a brood of 10 newly hatched ducklings, and survival was monitored for 24 days. Food was added ad libitum at five of the lakes, but not at the other five. Duckling survival was best modelled to include a treatment effect, with higher survival on lakes with food added, and a negative effect of harsh weather. As expected, duckling survival increased nonlinearly with age. Only one female remained on control lakes after 24 days, whereas four remained on lakes with food added. This is the first experimental demonstration that food may limit survival and reproductive output in breeding precocial birds. We argue that food limitation may be one reason why duckling mortality is high and why many lakes throughout the Holarctic have no breeding dabbling ducks.
Migration and stopover strategies of individual Dunlin along the Pacific coast of North America
Authors: Warnock Nils , Takekawa John Y , Bishop Mary Anne
Published: February 2005

We radio-marked 18 Dunlin, Calidris alpina (L., 1758), at San Francisco Bay, California, and 11 Dunlin at Grays Harbor, Washington, and relocated 90% of them along the 4200 km long coastline from north of San Francisco Bay to the Yukon–Kuskokwim Delta, Alaska. The Copper River Delta, Alaska, was the single most important stopover site, with 79% of the marked birds detected there. Our second most important site was the Willapa Bay and Grays Harbor complex of wetlands in Washington. The mean length of stay past banding sites ranged from 1.0 to 3.8 days. Controlling for date of departure, birds banded at San Francisco Bay had higher rates of travel to the Copper River Delta than those banded at Grays Harbor. The later a bird left a capture site, the faster it traveled to the Copper River Delta. Length of stay at the Copper River Delta was inversely related to arrival date. We did not find any effect of sex on travel rate or length of stay. Combining the results of this study with our previous work on Western Sandpipers, Calidris mauri (Cabanis, 1875), reveals variation of migration strategies used within and among shorebird species along the eastern Pacific Flyway.
Haldane's rule and American black duck × mallard hybridization
Authors: Kirby Ronald E , Sargeant Glen A , Shutler Dave
Published: February 2005

Species ratios and rangewide distributions of American black ducks (Anas rubripes Brewster, 1902) and mallards (Anas platyrhynchos L., 1758) have undergone recent changes. Mechanisms behind these changes are not known with certainty, but recent investigations have focused on the possibility of competitive exclusion and the consequences of hybridization. Consequences of hybridization have been difficult to assess because of the difficulty in identifying hybrids beyond the F1generation and lack of means to quantify introgression in wild populations. We documented a postmating isolating mechanism between the two species that follows Haldane's rule in controlled, interspecific matings in captive populations. Hybridization reduces the proportion of F1females available to return to the breeding grounds in the subsequent year. This effect, although likely small in overall population consequences in any year, may be of local significance and may contribute to recent reports of range shifts in both American black ducks and mallards.
The importance of aquatic and terrestrial habitat for the European pond turtle (Emys orbicularis): implications for conservation planning and management
Authors: Ficetola G F , Padoa-Schioppa E , Monti A , Massa R , Bernardi F De , Bottoni L
Published: February 2005

The European pond turtle, Emys orbicularis (L., 1758), is threatened throughout its distribution, prompting management of habitats and populations for conservation. Quantitative data on habitat requirements for this species are needed to better evaluate which areas are the most suitable, or what actions can improve habitat suitability. We studied relationships between the distribution and abundance of E. orbicularis and the environment by analysing water quality and features of 39 wetland and upland habitats in the Po River delta of northern Italy; visual transects and point counts were used to determine turtle presence and relative abundance. Emys orbicularis occurs more frequently and abundantly in permanent wetlands surrounded by woodlands, and its presence does not appear to be related to water eutrophication. Woodlands strongly influence adjacent wetland features and may be important for turtles' terrestrial activities such as nesting and dispersal. Habitat management and conservation plans for E. orbicularis should include protection of extensive terrestrial woodland habitat containing diverse wetland systems, to support turtle survival at different life-history stages. The requirements for wetlands and natural terrestrial habitat are difficult to meet in the currently human-dominated European lowlands; nevertheless, conservation plans for this species should take a broad-scale approach.
Effect of the cestode macroparasite Schistocephalus pungitii on the reproductive success of ninespine stickleback, Pungitius pungitius
Authors: Heins David C , Ulinski Britt , Johnson Jill , Baker John A
Published: February 2005

We quantified the relationship between reproductive status in the ninespine stickleback, Pungitius pungitius (L., 1758), and parasitism by plerocercoids of the cestode Schistocephalus pungitii Dubinina, 1959 in Airolo Lake, Alaska, using fish specimens from the 1994, 1998, and 2000 reproductive seasons. Infected females were inhibited from producing clutches of eggs and infected males showed much-reduced testicular condition. These deleterious effects on reproduction appear to involve nutrient theft. In addition, there appears to be a greater physical effect of the parasites crushing the gonads of host fish. The results of this study support the theoretical prediction that S. pungitii is a parasitic castrator, as the fitness of the majority of infected female ninespine stickleback was apparently reduced to zero, and there may be a similar effect among the majority of male ninespine stickleback. The symptoms of infection may represent adaptive parasite manipulations resulting in larger, more fecund parasites or an extended parasite-transmission period, although the possibility that the symptoms represent nonadaptive side effects cannot be excluded.
Reverse development in Cnidaria
Authors: Piraino S , De Vito D , Schmich J , Bouillon J , Boero F
Published: February 2005

Cnidarians have long been considered simple animals in spite of the variety of their complex life cycles and developmental patterns. Several cases of developmental conversion are known, leading to the formation of resting stages or to offspring proliferation. Besides their high regenerative and asexual-reproduction potential, a number of cnidarians can undergo ontogeny reversal, or reverse development: one or more stages in the life cycle can reactivate genetic programs specific to earlier stages, leading to back-transformation and morph rejuvenation. The switch is achieved by a variable combination of cellular processes, such as transdifferentiation, programmed cell death, and proliferation of interstitial cells. The potential for ontogeny reversal has limited ecological meaning and is probably just an extreme example of a more general strategy for withstanding unfavourable periods and allowing temporal persistence of species in the environment.
Changes in mesopredator-community structure in response to urbanization
Authors: Prange Suzanne , Gehrt Stanley D
Published: February 2005

Common raccoons (Procyon lotor (L., 1758)), Virginia opossums (Didelphis virginiana Kerr, 1792), and striped skunks (Mephitis mephitis (Schreber, 1776)) are common urban inhabitants, yet their relative demographic response to urbanization is unknown. Urbanization often affects community structure, and understanding these effects is essential in rapidly changing landscapes. We examined mesopredator-community structure in small and large patches of natural habitat surrounded by urban, suburban, or rural matrices. We created generalized logit models using road-survey and livetrapping data to examine effects of surrounding land use on proportions of opossums and skunks relative to raccoons, while accounting for effects of season and year and their interactions. For large sites, the land use × season model was chosen for both data sets, and occurrence of opossums and skunks relative to raccoons was higher at the rural site (P < 0.001 for all tests). For small sites, the land-use model best fit the road-survey data, with a higher occurrence of skunks relative to raccoons at the rural site (χ2 = 21.06, df = 1, P < 0.001). However, the season model best fit the trapping data for small sites. Our data indicated that raccoons exhibited a greater demographic response to urbanization, suggesting that they exploit anthropogenic resources more efficiently. Although numerous reasons exist for disparity in anthropogenic-resource use, differences in intraspecific tolerance and the role of learning in foraging behaviors were best supported by our observations.
LONG JUMP: MECHANICAL AND ENERGETIC ASPECTS
Authors: KARALIS T. K.
Published: February 2005

The use of variation techniques is applied to investigate jumper's posture at take-off, resulting in maximum distance of jump. Explicit expressions have been derived between: (i) the take-off angle ϕT (formed by the line connecting the contact point of the leg driving the jump with the ground to the centre of mass position and the horizontal), (ii) the ratio [Formula: see text] of the mean vertical component of the ground reaction force vector to athlete's weight at take-off, (iii) the time spent for the mid-support/take-off phase TT, and (iv) the change in the vertical component of the displacement of the centre of mass compared with the take-off foot ΔyT, measured between two extreme postures, i.e. the mid-support and the take-off phase. The method is illustrated by calculating the state vector [Formula: see text] at take-off, in connection with the take-off angle ϕT. The results are compared to direct measurements from real long jumps.
STEP SIZE IN ACTIVATED RABBIT SARCOMERES IS INDEPENDENT OF FILAMENT OVERLAP
Authors: NAGORNYAK EKATERINA M. , POLLACK GERALD H. , BLYAKHMAN FELIX A.
Published: February 2005

Investigations carried out on single cardiac and bumblebee myofibrils have shown stepwise sarcomere-length change of ~2.7 nm.1 We have carried out parallel measurements on single myofibrils from rabbit psoas muscle. Activated specimens were released or stretched using a motor-imposed ramp. With a high-resolution algorithm, we found that step sizes were always integer multiples of 2.7 nm, whether the length change was positive or negative, and independent of ramp velocity. Also, the influence of initial sarcomere length was studied, and found to be negligible. The value 2.7 nm, seen consistently, is equal to the linear repeat of actin monomers along the thin filament, a result that ties dynamical events to molecular structure, and places narrow constraints on any proposed molecular mechanism.
DETERMINATION OF AORTIC PRESSURE-TIME PROFILE, ALONG WITH AORTIC STIFFNESS AND PERIPHERAL RESISTANCE
Authors: ZHONG L. , GHISTA DHANJOO N. , NG E. Y. K. , LIM S. T. , CHUA T. S. J.
Published: February 2005

Aortic pressure measurement is of significant clinical importance. However, the techniques require invasive approach, such as cardiac catheterization. In this study, we are providing the analysis for the aortic pressure to be determined non-invasively, as well as indicating how it can be employed to determine cardiac contractility, compliance and peripheral resistance. We record systolic and diastolic pressure during the cardiac cycle using cuff method, assumed that the systolic phase of the supra-systolic cuff signal and the diastolic phase of the sub-diastolic cuff signal most closely approximate systolic and diastolic aortic pressure, respectively. The pressure curves for the systolic phase are derived from the aortic volume-time curve. In both Ayuredic-medicine and traditional Chinese-medicine, the pressure-pulse shape is felt to provide diagnosis information concerning diseases and disorders. In this regard, a precise evaluation of the aortic pressure-time profile and correlation of its shape parameters with diseases (using traditional Chinese and Ayuredic medical knowledge-base system) would constitute a significant contribution to medicine.
COHOMOLOGY OF THE VECTOR FIELDS LIE ALGEBRAS ON ℝℙ1 ACTING ON BILINEAR DIFFERENTIAL OPERATORS
Authors: BOUARROUDJ SOFIANE
Published: February 2005

The main topic of this paper is two-fold. First, we compute the first relative cohomology group of the Lie algebra of smooth vector fields on the projective line, Vect(ℝℙ1), with coefficients in the space of bilinear differential operators that act on tensor densities, [Formula: see text], vanishing on the Lie algebra sl(2, ℝ). Second, we compute the first cohomology group of the Lie algebra sl(2, ℝ) with coefficients in [Formula: see text].
A DE RHAM ISOMORPHISM IN SINGULAR COHOMOLOGY AND STOKES THEOREM FOR STRATIFOLDS
Authors: EWALD CHRISTIAN-OLIVER
Published: February 2005

We study the de Rham cohomology of a class of spaces with singularities which are called stratifolds. Such spaces occur in mathematical and theoretical physics. We generalize two classical results from the analysis of smooth manifolds, with outstanding applications in physics, to the class of stratifolds. The first one is Stokes theorem, the second one is the de Rham theorem which states that the de Rham cohomology of a stratifold is isomorphic to its singular cohomology with coefficients in ℝ. In fact, we give an explicit geometric construction of this isomorphism, given by integrating forms over stratifolds.
ALIGNMENT AND ALGEBRAICALLY SPECIAL TENSORS IN LORENTZIAN GEOMETRY
Authors: MILSON R. , COLEY A. , PRAVDA V. , PRAVDOVÁ A.
Published: February 2005

We develop a dimension-independent theory of alignment in Lorentzian geometry, and apply it to the tensor classification problem for the Weyl and Ricci tensors. First, we show that the alignment condition is equivalent to the principal null direction equation. In 4 dimensions this recovers the usual Petrov types are recovered. For higher dimensions we prove that, in general, a Weyl tensor does not possess any aligned directions. We then go on to describe a number of additional algebraic types for the various alignment configurations. For the case of second-order symmetric (Ricci) tensors, we perform the classification by considering the geometric properties of the corresponding alignment variety.
THE QUANTUM-CLASSICAL TRANSITION: THE FATE OF THE COMPLEX STRUCTURE
Authors: MARMO G. , SCOLARICI G. , SIMONI A. , VENTRIGLIA F.
Published: February 2005

According to Dirac, fundamental laws of Classical Mechanics should be recovered by means of an "appropriate limit" of Quantum Mechanics. In the same spirit it is reasonable to enquire about the fundamental geometric structures of Classical Mechanics which will survive the appropriate limit of Quantum Mechanics. This is the case for the symplectic structure. On the contrary, such geometric structures as the metric tensor and the complex structure, which are necessary for the formulation of the Quantum theory, may not survive the Classical limit, being not relevant in the Classical theory. Here we discuss the Classical limit of those geometric structures mainly in the Ehrenfest and Heisenberg pictures, i.e. at the level of observables rather than at the level of states. A brief discussion of the fate of the complex structure in the Quantum-Classical transition in the Schrödinger picture is also mentioned.
Endometriosis: New Genetic Approaches and Therapy
Authors: Barlow David H. , Kennedy Stephen
Published: February 2005

Endometriosis is a relatively common condition in women of reproductive age and is associated with considerable morbidity. Despite an extensive literature describing its multiple clinical manifestations, their management, and many aspects of the biology of endometriotic lesions, the pathophysiological mechanisms involved remain poorly understood. A genetic component in endometriosis is now recognized, and several groups have taken up the challenge of using genetic techniques to identify the aberrant molecular and cellular mechanisms in endometriosis with the intention of providing much-needed insights that might, in turn, lead to new therapies. The techniques that have been applied include expression profiling, tumor genetic studies, functional candidate gene studies, and linkage studies that can adopt a hypothesis-free approach. This review describes the current status of these studies and explores the prospects for new therapies.
Aptamers: An Emerging Class of Therapeutics
Authors: Nimjee Shahid M. , Rusconi Christopher P. , Sullenger Bruce A.
Published: February 2005

Numerous nucleic acid ligands, also termed decoys or aptamers, have been developed during the past 15 years that can inhibit the activity of many pathogenic proteins. Two of them, Macugen and E2F decoy, are in phase III clinical trials. Several properties of aptamers make them an attractive class of therapeutic compounds. Their affinity and specificity for a given protein make it possible to isolate a ligand to virtually any target, and adjusting their bioavailability expands their clinical utility. The ability to develop aptamers that retain activity in multiple organisms facilitates preclinical development. Antidote control of aptamer activity enables safe, tightly controlled therapeutics. Aptamers may prove useful in the treatment of a wide variety of human maladies, including infectious diseases, cancer, and cardiovascular disease. We review the observations that facilitated the development of this emerging class of therapeutics, summarize progress to date, and speculate on the eventual utility of such agents in the clinic.
Monogenic Obesity in Humans
Authors: Farooqi I. Sadaf , O'Rahilly Stephen
Published: February 2005

Until relatively recently, the small number of identifiable inherited human diseases associated with marked obesity were complex, pleiotropic developmental disorders, the molecular basis for which were entirely obscure. The molecular basis for many of these complex syndromes, such as Bardet Beidl syndrome, has been revealed, providing novel insights into processes essential for human hypothalamic function and energy balance. In addition to these discoveries, which were the fruits of positional cloning, the molecular constituents of the signaling pathways responsible for the control of mammalian energy homeostasis have been identified, largely through the study of natural or artificial mutations in mice. We discuss the increasing number of human disorders that result from genetic disruption of the leptin-melanocortin pathways that have been identified. Practical implications of these findings for genetic counseling, prognostication, and even therapy have already emerged.
Enterostatin decreases postprandial pancreatic UCP2 mRNA levels and increases plasma insulin and amylin
Authors: Arsenijevic Denis , Gallmann Eva , Moses William , Lutz Thomas , Erlanson-Albertsson Charlotte , Langhans Wolfgang
Published: February 2005

This study investigated the chronic effect of enterostatin on body weight and some of the associated changes in postprandial metabolism. Rats were adapted to 6 h of food access/day and a choice of low-fat and high-fat (HF) food and then given enterostatin or vehicle by an intraperitoneally implanted minipump delivering 160 nmol enterostatin/h continuously over a 5-day infusion period. Enterostatin resulted in a slight but significant reduction of HF intake and body weight. After the last 6-h food access period, enterostatin-treated animals had lower plasma triglyceride and free fatty acid but higher plasma glucose and lactate levels than control animals. Enterostatin infusion resulted in increased uncoupling protein-2 (UCP2) expression in various tissues, including epididymal fat and liver. UCP2 was reduced in the pancreas of enterostatin-treated animals, and this was associated with increased plasma levels of insulin and amylin. Whether these two hormones are involved in the observed decreased food intake due to enterostatin remains to be determined. As lipid metabolism appeared to be altered by enterostatin, we measured peroxisome proliferator-activated receptor (PPAR) expression in tissues and observed that PPARα, -β, -γ1, and -γ2 expression were modified by enterostatin in epididymal fat, pancreas, and liver. This further links altered lipid metabolism with body weight loss. Our data suggest that alterations in UCP2 and PPARγ2 play a role in the control of insulin and amylin release from the pancreas. This implies that enterostatin changes lipid and carbohydrate metabolic pathways in addition to its effects on food intake and energy expenditure.
Thyroid hormone regulates tubulin expression in mammalian liver. Effects of deleting thyroid hormone receptor-α or -β
Authors: Vallejo Carmen G. , Seguido Ana M. , Testillano Pilar S. , Risueño María-Carmen
Published: February 2005

Microtubules are made from polymers of α/β dimers. We have observed in rat liver that, on the first day after birth, α-subunit is relatively high and β-subunit low with respect to adult values. In the hypothyroid neonate, both subunits were found to be low, therefore indicating that thyroid hormone (TH) regulates these developmental changes. TH was also found to activate tubulin expression in adult liver, especially β-subunit. To investigate the role of TH receptors (TRs) in tubulin expression, we analyzed mice lacking TRα or TRβ compared with the wild type in both normal and TH-deprived adult animals. The results suggest that, in vivo, β-tubulin protein expression in the liver is primarily under TRβ positive control. In euthyroid mice lacking TRβ, β-tubulin expression was low. However, in the corresponding hypothyroid animals, it was found increased, therefore suggesting that the unliganded TRα might also upregulate β-tubulin expression. Accordingly, TH administration to hypothyroid TRβ-deprived mice reduced their high β-tubulin expression. In parallel, the relatively high messenger level observed with these hypothyroid animals was reduced to the euthyroid level after T3treatment. The microtubular network of the mutant livers appeared, by immunofluorescence confocal microscopy, generally disorganized and drastically reduced in β-tubulin in mice lacking TRβ. In conclusion, our results indicate that β-tubulin is critically controlled by TRβ in the liver and that both TRs are probably needed to maintain the microtubular network organization of the liver.