bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of circannual patterns of metabolic recovery from activity inRana catesbeianaat 15°C
Authors: Petersen A. M. , Gleeson T. T. 
Published: May 2007

SUMMARYWe characterized carbohydrate metabolism following activity in the American bullfrog, Rana catesbeiana, and compared whole body metabolic profiles between two seasons. Forty-eight adult male Rana catesbeianawere chronically cannulated and injected with[U-14C]l-lactic acid sodium salt in either summer (June)or winter (January) after acclimation for 2 weeks at 15°C with a 12 h:12 h L:D photoperiod. Following injection with [14C]lactate, frogs were either allowed to rest for 240 min (REST), hopped for 2 min on a treadmill and immediately sacrificed (PE), or hopped for 2 min on a treadmill and allowed to recover for 240 min (REC 4). Exercise caused a significant increase in blood lactate level from 2.7±0.1 mmol l–1 at rest to 17.0±2.1 mmol l–1 immediately following exercise. This increase persisted throughout the recovery period, with average blood lactate level only reduced to 13.7±1.1 mmol l–1 after 240 min of recovery, despite complete recovery of intramuscular lactate levels. Lactate levels were not significantly different between seasons in any treatment (REST, PE, REC4), in either gastrocnemius muscle or blood. The vast majority of [14C]lactate was recovered in the muscle, in both winter (86.3%) and summer (87.5%). Season had no effect on total amount of 14C label recovered. [14C]Lactate was measured in the forms of lactate, glucose and glycogen, in the liver and the muscle sampled. The most robust difference found in seasonal metabolism was that both the liver and the gastrocnemius contained significantly higher levels of intracellular free glucose under all treatments in winter. These data suggest that, overall, bullfrogs accumulate and slowly clear lactate in a manner quite similar to findings in fish, other amphibians and lizards. Additionally, our findings indicate that lactate metabolism is not highly influenced by season alone, but that intracellular glucose levels may be sensitive to annual patterns.
Tribute to P. L. Lutz: putting life on `pause' – molecular regulation of hypometabolism
Authors: Storey Kenneth B. , Storey Janet M. 
Published: May 2007

SUMMARYEntry into a hypometabolic state is an important survival strategy for many organisms when challenged by environmental stress, including low oxygen, cold temperatures and lack of food or water. The molecular mechanisms that regulate transitions to and from hypometabolic states, and stabilize long-term viability during dormancy, are proving to be highly conserved across phylogenic lines. A number of these mechanisms were identified and explored using anoxia-tolerant turtles as the model system, particularly from the research contributions made by Dr Peter L. Lutz in his explorations of the mechanisms of neuronal suppression in anoxic brain. Here we review some recent advances in understanding the biochemical mechanisms of metabolic arrest with a focus on ideas such as the strategies used to reorganize metabolic priorities for ATP expenditure, molecular controls that suppress cell functions (e.g. ion pumping, transcription, translation, cell cycle arrest),changes in gene expression that support hypometabolism, and enhancement of defense mechanisms (e.g. antioxidants, chaperone proteins, protease inhibitors) that stabilize macromolecules and promote long-term viability in the hypometabolic state.
Tribute to P. L. Lutz: respiratory ecophysiology of coral-reef teleosts
Authors: Nilsson Göran E. , Hobbs Jean-Paul A. , Östlund-Nilsson Sara 
Published: May 2007

SUMMARYOne of the most diverse vertebrate communities is found on tropical coral reefs. Coral-reef fishes are not only remarkable in color and shape, but also in several aspects of physiological performance. Early in life, at the end of the pelagic larval stage, coral-reef fishes are the fastest swimmers of all fishes in relation to body size, and show the highest specific rates of maximum oxygen uptake. Upon settling on the reef, coral-reef fishes have to adopt a demersal lifestyle, which involves coping with a habitat that can become severely hypoxic, and some fishes may even have to rely on air breathing when their coral homes become air exposed. Oxygen availability appears to be a major ambient selection pressure, making respiratory function a key factor for survival on coral reefs. Consequently, hypoxia tolerance is widespread among coral-reef fishes. Hypoxia can even be a factor to gamble with for those fishes that are mouthbrooders, or a factor that the coral inhabitants may actively seek to reduce by sleep-swimming at night. Here, we summarize the present knowledge of the respiratory ecophysiology of coral-reef teleosts. From an ecophysiological perspective, the coral reef is an exciting and largely unexplored system for testing existing hypotheses and making new discoveries.
Absorption of sugars in the Egyptian fruit bat (Rousettus aegyptiacus): a paradox explained
Authors: Tracy Christopher R. , McWhorter Todd J. , Korine Carmi , Wojciechowski Michal S. , Pinshow Berry , Karasov William H. 
Published: May 2007

SUMMARYTwo decades ago D. J. Keegan reported results on Egyptian fruit bats(Rousettus aegyptiacus, Megachiroptera) that were strangely at odds with the prevailing understanding of how glucose is absorbed in the mammalian intestine. Keegan's in vitro tests for glucose transport against a concentration gradient and with phloridzin inhibition in fruit bat intestine were all negative, although he used several different tissue preparations and had positive control results with laboratory rats. Because glucose absorption by fruit bats is nonetheless efficient, Keegan postulated that the rapid glucose absorption from the fruit bat intestine is not through the enterocytes, but must occur via spaces between the cells. Thus, we hypothesized that absorption of water-soluble compounds that are not actively transported would be extensive in these bats, and would decline with increasing molecular mass in accord with sieve-like paracellular absorption. We did not presume from Keegan's studies that there is no Na+-coupled, mediated sugar transport in these bats, and our study was not designed to rule it out, but rather to quantify the level of possible non-mediated absorption. Using a standard pharmacokinetic technique, we fed,or injected intraperitonealy, the metabolically inert carbohydrates l-rhamnose (molecular mass=164 Da) and cellobiose (molecular mass=342 Da), which are absorbed by paracellular uptake, and 3-O-methyl-d-glucose (3OMd-glucose), a d-glucose analog that is absorbed via both mediated(active) and paracellular uptake. As predicted, the bioavailability of paracellular probes declined with increasing molecular mass (rhamnose,62±4%; cellobiose, 22±4%) and was significantly higher in bats than has been reported for rats and other mammals. In addition, fractional absorption of 3OMd-glucose was high (91±2%). We estimated that Egyptian fruit bats rely on passive, paracellular absorption for the majority of their glucose absorption (at least 55% of 3OMd-glucose absorption), much more than in non-flying mammals.
Runx3/AML2/Cbfa3 Regulates Early and Late Chondrocyte Differentiation
Authors: Soung Do Y , Dong Yufeng , Wang Yong Jun , Zuscik Michael J , Schwarz Edward M , O'Keefe Regis J , Drissi Hicham 
Published: May 2007

Abstract
We studied the expression and function of Runx3 during chondrogenesis and chondrocyte maturation. We found that Runx3 is essential for mediating the early stage of endochondral ossification through cooperation with other Runx family members.
Introduction: Runx proteins are spatially and temporally co-expressed during skeletal formation. A cooperative and/or redundant function between these factors was postulated, yet the mechanisms underlying these cooperative effects are unknown.
Materials and Methods: Expression patterns of Runx3 transcripts were assessed during mouse embryonic developments and limb bud—derived mesenchymal cell differentiation into mature chondrocytes by real-time RT-PCR. Runx3 protein distribution was also determined by immunohistochemistry in mouse embryos. Runx3 gain and loss of function was performed through overexpression and siRNA knockdown of Runx3 into the limb bud—derived cell line MLB13MYC clone17, respectively. Co-transfection experiments were performed in clone 17 cells using the Runx1 promoter and Runx3 cDNA. Promoter activity was measured by luciferase reporter assay.
Results: Both Runx3 isoforms are significantly upregulated at the onset of cartilage mineralization and bone formation in E15.5 mice. This upregulation follows that of Sox9 and is concomitant with that of alkaline phosphatase. Furthermore, Runx3 expression remains high during later stages of embryonic development when the levels of osteocalcin are maximal. We determined the expression patterns of Runx3 during chondrogenesis and chondrocyte maturation using mouse limb bud—derived micromass cultures between days 3 and 21. Whereas Runx3 mRNAs are progressively upregulated between days 3 and 14, it is dramatically downregulated at day 21. Markers of chondrocyte maturation alkaline phosphatase and type X collagen are upregulated and maintained throughout the 21 days of culture. Runx3 role in mediating chondrocyte terminal differentiation through gain and loss of function in MLB13MYC clone17 shows that Runx3 regulates both early and late markers of chondrocyte maturation. Finally, Runx3 transcriptionally inhibits Runx1 expression in chondrocytes.
Conclusions: We show a role for Runx3 in mediating stage-specific chondrocyte maturation. Our study clearly suggests that, whereas Runx3 may cooperate with Runx2 to induce chondrocyte terminal differentiation, it inhibits Runx1 expression during late maturation.
Effect of Fracture on Bone Turnover Markers: A Longitudinal Study Comparing Marker Levels Before and After Injury in 113 Elderly Women
Authors: Ivaska Kaisa K , Gerdhem Paul , Åkesson Kristina , Garnero Patrick , Obrant Karl J 
Published: May 2007

Abstract
In this longitudinal, prospective, and population-based study (n = 1044), seven BTMs were assessed before and after trauma in 113 elderly women (85 with fractures). Markers were not altered in the immediate postfracture period but were clearly elevated during fracture repair. Recent fracture should thus be taken into account when markers are used in clinical practice.
Introduction: Fracture may influence the levels of bone turnover markers (BTM) and have implications for their use in clinical practice. In this longitudinal, prospective, and population-based study, we assessed prefracture levels of BTMs and compared them with postfracture levels of the same individuals immediately after fracture and during fracture repair. This is the first study in which the effect of fracture on bone markers has been evaluated with prefracture samples available.
Materials and Methods: Serum and urine were collected at the emergency unit from 85 women (77.9 ± 1.8 yr) who sustained a fracture after low-energy trauma and 28 controls (77.8 ± 2.0 yr) with similar trauma but no fracture. All were participants of the Malmö OPRA study (n = 1044), and pretrauma samples were collected 1.05 ± 0.85 yr before. Bone turnover was assessed by seven different BTMs reflecting different stages of bone metabolism {C-terminal cross-linked telopeptides of type I collagen [S-CTX], S-TRACP5b, N-terminal propeptides of type I collagen [S-PINP], serum osteocalcin (S-OC[1–49] and S-TotalOC), urinary deoxypyridinoline [U-DPD], and urinary osteocalcin [U-OC]}.
Results: BTMs sampled within a few hours after fracture were not altered from preinjury levels. Both bone formation and bone resorption markers were, however, significantly increased 4 mo after fracture. The elevation was most pronounced after hip fracture. Bone turnover remained elevated up to 12 mo after fracture.
Conclusions: We believe this study extends our knowledge on the skeletal postfracture metabolic processes. In addition, it may provide a basis for future means to monitor pharmacological intervention promoting fracture healing.
Maternal Age And Birth Weight Characteristics of Twins Born to Nulliparous Mothers: A Population Study
Authors: Blickstein Isaac , Goldman Ran D. , Mazkereth Ram 
Published: May 2007

AbstractIn order to examine birth weight characteristics of twins delivered to nulliparous mothers in relation to maternal age, we used a population-based cohort of Israeli twins delivered between 1993–98 to select all 4793 (37.6%) nulliparas who delivered twins. Maternal age was subdivided as less than 20 years, 20–24, 25–29, 30–34, 35–39, and 40 years or more. We counted the frequencies of each total twin birth weight (twin A+twin B) in each of three categories (less than 3000, 3000–4999, and more than 5000 g) and the frequency of very low birth weight (VLBW, less than 1500 g) neonates in each of the six maternal age categories. There were significantly more nulliparas in the twin population at age groups less 30 years and significantly less at ages 30 years or more. We found a highly significant inverse correlation between the proportion of nulliparas and maternal age group, decreasing from 71.8% at less than 20 years to 18.6% at age 35–39 years (% nulliparas = 85 − 13.7 × age group, Pearson R2 = 0.98). However, this trend changed abruptly to the observed figure of 25.9% nulliparas aged 40 years or more instead of the expected 2.8%. We failed to reveal any significant difference in birth weight characteristics between the maternal age groups (all p > 0.05, all confidence intervals included 1.0). The more than tenfold deviation of the observed from the predicted frequency of nulliparas aged 40 years or more suggests that a different relationship between parity and age occurs at this age group. Maternal age of nulliparas is not associated with different birth weight characteristics of their twins.
Genetics of Cognition: Outline of a Collaborative Twin Study
Authors: Wright Margie , De Geus Eco , Ando Juko , Luciano Michelle , Posthuma Danielle , Ono Yutaka , Hansell Narelle , Van Baal Caroline , Hiraishi Kai , Hasegawa Toshikazu , Smith Glen , Geffen Gina , Geffen Laurie , Kanba Shigenobu , Miyake Akira , Martin Nick , Boomsma Dorret 
Published: May 2007

AbstractAmultidisciplinary collaborative study examining cognition in a large sample of twins is outlined. A common experimental protocol and design is used in The Netherlands, Australia and Japan to measure cognitive ability using traditional IQ measures (i.e., psychometric IQ), processing speed (e.g., reaction time [RT] and inspection time [IT]), and working memory (e.g., spatial span, delayed response [DR] performance). The main aim is to investigate the genetic covariation among these cognitive phenotypes in order to use the correlated biological markers in future linkage and association analyses to detect quantitativetrait loci (QTLs). We outline the study and methodology, and report results from our preliminary analyses that examines the heritability of processing speed and working memory indices, and their phenotypic correlation with IQ. Heritability of Full Scale IQ was 87% in the Netherlands, 83% in Australia, and 71% in Japan. Heritability estimates for processing speed and working memory indices ranged from 33–64%. Associations of IQ with RT and IT (−0.28 to −0.36) replicated previous findings with those of higher cognitive ability showing faster speed of processing. Similarly, significant correlations were indicated between IQ and the spatial span working memory task (storage [0.31], executive processing [0.37]) and the DR working memory task (0.25), with those of higher cognitive ability showing better memory performance. These analyses establish the heritability of the processing speed and working memory measures to be used in our collaborative twin study of cognition, and support the findings that individual differences in processing speed and working memory may underlie individual differences in psychometric IQ.
Epidemiological trends in multiple births in the United States, 1971–1998
Authors: Kiely John L. , Kiely Michele 
Published: May 2007

AbstractThe astounding rise in multiple births in the United States continues. We analyzed live birth files from the U.S. National Center for Health Statistics. Twin, triplet, quadruplet, and quintuplet+ rates were calculated for the period 1971–1977 and for each year between 1990 and 1998. Triplet rates were also computed within categories of mother's education and age. The twin rate increased from 1.8% in 1971–77 to 2.8% in 1998. The rate of triplets increased 5.9-fold, quadruplets 11.9-fold, and quintuplets+ 5.3-fold between 1971–77 and 1998. Increases in triplet rates were much more marked among births to university-educated women and women 30 years and older. Among women 45 years and older, the triplet rate was approximately fifty times higher in 1998 than in 1971–77. This group of older women (≥ 45 years) had the highest multiple birth rate in 1998.
The Ten Commandments in Multiple Pregnancies
Authors: Di Renzo G.C. , Luzietti R. , Gerli S. , Clerici G. 
Published: May 2007

AbstractMultiple pregnancy represents a challenge for obstetrics and also poses significant psychological, social and economic problems. The chances of a successful outcome may be improved by appropriate preventive, diagnostic and management strategies, by the availability of specific skills and experience and by a multidisciplinary approach. In this paper are indicated and discussed, on the basis of current evidences, what can be considered the ten “commandments” in terms of providing optimal care in multiple pregnancies. In particular in this review we focus on the following topics: psychological support and clinical counseling; diagnosis and characterization of chorionicity; management at referral centers; individualization of care; avoidance of most frequent complications; consideration of specific pathologies; evaluation of fetal anatomy; monitoring of fetuses; planning of time and mode of delivery; monitoring of the mother during postpartum.
Controversial Issues in the Management of Multiple Pregnancies
Authors: Blickstein Isaac 
Published: May 2007

AbstractThe management of multiple pregnancies represents a true challenge for all sub-specialties concerned with perinatal medicine. Many issues were neglected over the years merely because they were rare and therefore considered not sufficiently important to merit clinical trials. This paper discusses a personal selection of controversial issues, such as multifetal pregnancy reduction of triplets and twins, special cases in multifetal preganncy reduction, need for invasive genetic studies, management of twin-twin transfusion, discordant fetal conditions, the definition of “term” in multiples, and the controversy about the mode of delivery.
Early Plasma Creatinine Values in Discordant Twins
Authors: Arad Ilan , Bar-Oz Benjamin , Peleg Ofra 
Published: May 2007

AbstractIt has been suggested that impairment of placental perfusion prior to delivery may manifest in early postnatal increase of creatinine values. We hypothesized that the smaller of a discordant set of twins would have a higher initial plasma creatinine value and decided to measure early plasma creatinine levels in discordant twins in order to evaluate whether this value may serve as an index of impaired placental perfusion. Plasma creatinine, urea nitrogen and blood hematocrit values were simultaneously measured in 35 sets of twins during the first day of life. The sets of twins were divided into 2 groups according to birth weight difference. Thus, 18 sets of discordant twins with birth weight difference greater than 15% comprised the GT group and 17 sets of twins with birth weight difference less than or equal to 15% comprised the LE group. The differences between the values obtained within each group were analyzed using the Wilcoxon Signed Rank test. In the GT group the mean plasma creatinine level of the smaller twins was significantly higher than the level of the larger ones (p = 0.03), but there was no statistically significant difference between values obtained in twins of the LE group. The mean plasma urea level was higher in the larger twins of both groups, however only the difference in the GT group was statistically significant (p = 0.01). The mean hematocrit of the smaller twins was higher in both groups, but only the difference in the LE group was statistically significant (p = 0.02). Generally, there was a negative correlation between gestational age and early creatinine values. These results apparently support the notion that prenatal exposure to impaired placental perfusion may compromise the creatinine clearance of the fetus and result in higher early creatinine values. Since the creatinine values in our growth-retarded twins were within the normal range, no distinguishing line for evidence of a uterine-placental compromise could be drawn. Whether a certain early plasma creatinine value is suggestive or indicative of an intra-uterine hypoxic-ischemic insult, should be determined by documented instances of severe fetal compromise prior to delivery.
Ultrasound Determination of Chorionicity in Twin Pregnancy: Accuracy and Operator Experience
Authors: Devlieger Roland G.L. , Demeyere Thomas , Deprest Jan A. , Schoubroeck Dominique Van , Witters Ingrid , Timmerman Dirk , Hanssens Myriam 
Published: May 2007

AbstractTo evaluate the accuracy of ultrasound in early detection of chorionicity and amnionicity in twin pregnancies and evaluate the role of operator-experience, a prospective follow up of 87 consecutive twin pregnancies was performed. Chorionicity and amnionicity were determined by 17 different observers, divided in 2 groups on the basis of their experience, using a composite of US markers at the first US examination confirming a viable intrauterine twin pregnancy. Accuracy of prediction was determined for both groups by comparison with postnatal pathology. From the 87 pregnancies examined at 10.1 (minimum 5.5 weeks, maximum 26.0) weeks of gestation, pathology was available in 82 cases and a correct prediction of chorionicity was made in all but two cases, both being diagnosed as monochorionic while dichorionic by observers belonging the more experienced group. No monochorionic pregnancy was missed and amnionicity was correctly diagnosed in all cases, including two monoamniotic twins. We conclude that use of a composite of ultrasound markers for early detection of chorionicity and amnionicity is reliable in a clinical setting where physicians with a variable degree of experience perform ultrasound examination.
Estimated Number of Multiplets Under 16 Years Using Two Sets of Census Data in Japan: 1990 and 1995
Authors: Imaizumi Yoko 
Published: May 2007

AbstractData for sets of multiples under 16 years of age were obtained from the population censuses of Japan in 1990 and 1995. These numbered 147,188 twin pairs, 1410 sets of triplets, 59 sets of quadruplets, and 3 sets of quintuplets in 1990, with the corresponding numbers in 1995 being 141,354, 2,211, 136 and 12, respectively. The total number of sets of multiples was 148,660 in 1990 and 143,713 in 1995. Twinning, triplet, quadruplet and quintuplet rates were estimated for each age. Rates of monozygotic twins and triplets remained constant age by age up to 15 years, while the dizygotic twinning rate, and rates of di- and tri-zygotic triplets decreased over the same period. Quadruplet and quintuplet rates also decreased. The accuracy of estimating number of multiples from census data is discussed using data on vital statistics.