bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chromatin Configurations in the Ferret Germinal Vesicle that Reflect Developmental Competence for In Vitro Maturation
Authors: Sun X , Li Z , Yi Y , Ding W , Chen J , Engelhardt JF , Leno GH 
Published: October 2008

ContentsIn several mammalian species, the configuration of germinal vesicle (GV) chromatin correlates with the developmental competence of oocytes. Yet, no study has been published on the configuration of GV chromatin in ferret, nor is it known whether a specific configuration predicts meiotic competence in this species, in spite of the potential importance of ferret cloning to the study of human disease and to species conservation efforts. Here, we report on an analysis of the chromatin configuration in ferret GV oocytes and on how they correlate with meiotic development. Three distinct configurations were identified based on the degree of chromatin condensation: (1) fibrillar chromatin (FC), featuring strands of intertwined chromatin occupying most of the visible GV region; (2) intermediate condensed chromatin (ICC), characterized by dense, irregular chromatin masses throughout the GV; and (3) condensed chromatin (CC), which is highly compact and centered around the nucleolus. We also found that chromatin configuration was related to the extent of association with cumulus cells in cumulus–oocyte complexes; CC‐configured oocytes were most often surrounded by a compact cumulus layer and also a compact corona but FC‐configured oocytes were associated with neither. In addition, increasing chromatin condensation corresponded to an increase in oocyte diameter. Finally, following in vitro culture, significantly more CC‐configured oocytes underwent maturation to meiotic metaphase II than did FC‐ or ICC‐configured oocytes. We conclude that, in ferret, chromatin condensation is related to the sequential achievement of meiotic competencies during oocyte growth and differentiation, and thus can be used as a predictor of competence.
Coating of Objects Introduced into the Oviduct of Pseudopregnant Rabbit Does
Authors: El‐Gayar M , Holtz W 
Published: October 2008

ContentsThis investigation addresses the possibility of providing mouse embryos or other foreign objects with a protective mucin coat by transferring them into the oviduct of a life rabbit doe. Mouse embryos at the 8 or 16‐cell stage, rabbit oocytes and latex spheres resembling mouse embryos in size were transferred to the ligated oviducts of ovulation‐induced rabbit does. The does were killed 24 h later to have their oviducts flushed. A large proportion of the latex spheres (89%) and of the ovulated oocytes of the recipient does (92%) was recovered. The recovery rates for transferred rabbit oocytes, either intact or with the zona pellucida removed, were 61% and 51%, respectively, whereas that for mouse embryos was extremely poor (20%). Rabbit oocytes with or without zona were enveloped in a thick mucin coat regardless whether they had been transferred or ovulated by the recipients. The same applied to empty rabbit zonae. Mouse embryos and latex spheres were also covered by a mucin coat, but it was four times thinner. While residing in the rabbit oviduct, the mouse embryos continued developing to a stage comparable to what would have been expected in situ. During the subsequent in vitro culture, mouse embryos continued developing to the expanded blastocyst stage. They did, yet, not hatch from the zona. It may be concluded that particles of various origins, when placed into the oviduct of ovulated rabbit does, will be provided with a mucin covering which is, however, considerably thinner than that surrounding oocytes or zonae pellucidae originating from rabbits.
Trypsin and Chymotrypsin are Involved in the Progesterone‐Induced Acrosome Reaction in Canine Spermatozoa
Authors: Deppe M , Risopatrón J , Sánchez R 
Published: October 2008

ContentsAcrosomal proteases allow the spermatozoon not only to cross the cumulus cells and penetrate the zona pellucida of the oocyte, but also they are needed for the acrosome reaction process (AR). The present study evaluated in vitro the role of trypsin and chymotrypsin in the acrosome reaction of canine spermatozoa by means of protease inhibitors. Spermatozoa obtained from the second fraction of the ejaculate and devoid of seminal plasma were re‐suspended in canine capacitation medium (CCM) and incubated at 38.5°C in 5% CO2. After 2 h (period of sperm capacitation), aliquots of sperm suspension were incubated separately with trypsin inhibitor NPGB (p‐nitrophenyl‐p′‐guanidino‐benzoate); TI (Trypsin inhibitor I‐S Type from soybean) and with chymotrypsin inhibitor TPCK (N‐tosyl‐L‐phenylalanine‐chloromethyl‐ketone) for 30 min. The AR was induced with progesterone and evaluated using the dual fluorescent staining technique ‘Hoechst and chlortetracycline’. Acrosomal exocytosis levels were statistically significant higher in the samples treated with progesterone than in the control without inducer. However, the trypsin inhibitors NPGB, TI and the chymotrypsin inhibitor TPCK reduced the percentage of AR when compared with the control with progesterone and without inhibitor (p < 0.001), where the AR values were 45.63 ± 3.8%, 51.63 ± 2.8%, 58.38 ±4.1% and 71.25 ± 4.9%, respectively. These results show that trypsin and chymotrypsin inhibitors are effective in blocking the acrosome reaction induced by progesterone in canine; in addition, they suggest the participation of respective proteases in the AR process in this species.
GROWTH HORMONE ATTENUATES MYOCARDIAL FIBROSIS IN RATS WITH CHRONIC PRESSURE OVERLOAD‐INDUCED LEFT VENTRICULAR HYPERTROPHY
Authors: Moreira Vanessa O , Pereira Camila A , Silva Mirella O , Felisbino Sergio L , Cicogna Antonio C , Okoshi Katashi , Aragon Flavio F , Padovani Carlos R , Okoshi Marina P , Castro Ana VB 
Published: October 2008

SUMMARY

The role of growth hormone (GH) in cardiac remodelling and function in chronic and persistent pressure overload‐induced left ventricular hypertrophy has not been defined. The aim of the present study was to assess short‐term GH treatment on left ventricular function and remodelling in rats with chronic pressure overload‐induced hypertrophy.
Twenty‐six weeks after induction of ascending aortic stenosis (AAS), rats were treated with daily subcutaneous injections of recombinant human GH (1 mg/kg per day; AAS‐GH group) or saline (AAS‐P group) for 14 days. Sham‐operated animals served as controls. Left ventricular function was assessed by echocardiography before and after GH treatment. Myocardial fibrosis was evaluated by histological analysis.
Before GH treatment, AAS rats presented similar left ventricular function and structure. Treatment of rats with GH after the AAS procedure did not change bodyweight or heart weight, both of which were higher in the AAS groups than in the controls. After GH treatment, posterior wall shortening velocity (PWSV) was lower in the AAS‐P group than in the control group. However, in the AAS‐GH group, PWSV was between that in the control and AAS‐P groups and did not differ significantly from either group. Fractional collagen (% of total area) was significantly higher in the AAS‐P and AAS‐GH groups compared with control (10.34 ± 1.29, 4.44 ± 1.37 and 1.88 ± 0.88%, respectively; P < 0.05) and was higher still in the AAS‐P group compared with the AAS‐GH group.
The present study has shown that short‐term administration of GH to rats with chronic pressure overload‐induced left ventricular hypertrophy induces cardioprotection by attenuating myocardial fibrosis.
TOWARDS PAINLESS COLONOSCOPY: A RANDOMIZED CONTROLLED TRIAL ON CARBON DIOXIDE‐INSUFFLATING COLONOSCOPY
Authors: Wong James C. H. , Yau Kevin K. , Cheung Hester Y. S. , Wong Denis C. T. , Chung Cliff C. , Li Michael K. W. 
Published: October 2008

Background:  Carbon dioxide (CO2) insufflation during colonoscopy was reported to reduce pain, but data are limited. The objective of this randomized controlled trial was to assess the effect of CO2 insufflation on pain during and after colonoscopy.Methods:  Patients were randomized into CO2 insufflation (CO2i) or air insufflation (AIRi) groups. Pain during and after the examination were recorded using a visual analogue scale. Other outcomes included the caecal intubation rate, time to reach the caecum and complication. With questionnaire, patients’ satisfaction and acceptance of the procedure were assessed.Results:  Over a 4‐month period, 96 patients were recruited. The caecal intubation rate was 96 and 98% in the CO2i group and the AIRi group, respectively. No complication occurred in the CO2i group whereas one patient from the AIRi group developed late haemorrhage after polypectomy. Patients in the CO2i group had a lower pain score during (P < 0.01) and 30 min after (P = 0.02) the examination. Significantly more patients in the CO2i group reported the examination as painless (visual analogue scale 0) during the procedure (45 vs 14%, P < 0.01) and 30 min after (70 vs 51%, P = 0.04). In both groups, high satisfaction scores were recorded. Most patients (93% for the CO2i group and 98% for the AIRi group) would accept another colonoscopy if indicated.Conclusion:  Insufflation with CO2 during colonoscopy results in less pain during and after the examination. Because of better tolerance, colonoscopy with CO2 insufflation might gain wide acceptance in the community to be used as a screening tool.
Microwave and millimetre wave sensors for crack detection
Authors: ZOUGHI R. , KHARKOVSKY S. 
Published: October 2008

ABSTRACTNon‐destructive detection and evaluation of stress‐induced fatigue cracks in metals is an important practical issue in several critical environments including surface transportation (steel bridges, railroad tracks, railroad car wheels, etc.), aerospace transportation (aircraft fuselage, landing gears, etc.) and power plants (steam generator tubings, etc.). Although there are several standard non‐destructive evaluation techniques, near‐field microwave and millimetre wave techniques have shown tremendous potential for significantly adding to the available non‐destructive ‘toolbox’ for this purpose. This paper serves as a review of recent advances made in this area and the capabilities of these techniques for detecting cracks and evaluating their various dimensional properties including determining a crack tip location accurately. These techniques include using open‐ended rectangular probes (in two distinct modes) and open‐ended coaxial probes.
Piezoelectric wafer active sensors for in situ ultrasonic‐guided wave SHM
Authors: YU L. , SANTONI‐BOTTAI G. , XU B. , LIU W. , GIURGIUTIU V. 
Published: October 2008

ABSTRACTIn situ structural health monitoring aims to perform on‐demand interrogation of the structure to determine the presence of service‐induced damage and defects using non‐destructive evaluation ultrasonic wave methods. Recently emerged piezoelectric wafer active sensors (PWAS) have the potential to significantly improve damage detection and health monitoring. PWAS are low‐profile transducers that can be permanently attached onto the structure or inserted in between composite laminates, and can perform structural damage detection in thin‐wall structures using guided wave methods (Lamb, Rayleigh, SH, etc.).This paper describes the analytical and experimental work of using PWAS‐guided waves for in situ structural damage detection on thin‐wall structures. We begin with reviewing the guided wave theory in plate structures and PWAS principles. The mechanisms of Lamb wave excitation and detection using PWAS is presented. Subsequently, we address in turn the use of PWAS to generate Lamb waves for damage (cracks and corrosion) detection in metallic structures. Pulse‐echo, pitch‐catch, phased array and time reversal methods are illustrated demonstrating that PWAS Lamb‐waves techniques are suitable for damage detection and structural health monitoring. The last part of the paper treats analytically and experimentally PWAS excitation and tuning in composite materials. The research results presented in this paper show that in situ SHM methodologies using PWAS transducers hold the promise for more efficient, effective and timely damage detection in thin‐wall structures.
Wear behaviour of an aluminium matrix composite
Authors: GARCÍA‐ROMERO A. , IRISARRI A. M. 
Published: October 2008

ABSTRACTThe wear behaviour of a composite material consisting in AS12UNG alloy reinforced with 15% short fibres of alumina has been studied. The material composition and the wear test conditions were defined in order to evaluate the potential performance of automotive pistons produced with such composite composition. As initially expected, the results indicate that an increase in the sliding velocity lead to higher wear rates in the stationary stages, and higher applied loads also induced acceleration in the wear process. Also, reciprocating sliding movement is clearly more damaging than the circular. However, results have shown that wear rates at 150 °C are lower than those recorded at room temperature representing a promising result for the use of this material in components that operate in this condition. This advantageous behaviour is lost at temperatures near to 300 °C, when a marked increase in the wear rate and a signification contribution of adhesive wear were observed.
A method to estimate plastic loads for elbows with non‐uniform thicknesses
Authors: KIM Y.‐J. , KIM N.‐H. , OH C.‐Y. , OH C.‐S. 
Published: October 2008

ABSTRACTThis paper provides a method to estimate plastic loads [defined by the twice‐elastic‐slope (TES)] for elbows with non‐uniform thicknesses under in‐plane bending and under internal pressure, based on systematic FE limit analyses using elastic‐perfectly plastic materials. The intrados thickness is assumed to be up to 30% thicker than the straight pipe thickness, whereas the extrados thickness up to 30% thinner. The FE plastic loads are compared with estimated ones using closed‐form approximations for elbows with uniform thicknesses, to provide guidance on the choice of a representative thickness to predict plastic loads for elbows with non‐uniform thicknesses. Results suggest that the use of the straight pipe thickness gives overall satisfactory predictions. Estimated plastic loads are conservative, and differ from FE results by less than 10% for all cases considered. Despite its simplicity, results look very promising, and thus the use of the straight pipe thickness can be recommended to estimate plastic loads for elbows with non‐uniform thicknesses in practice.
The nigrostriatal dopamine system of aging GFRα‐1 heterozygous mice: neurochemistry, morphology and behavior
Authors: Zaman Vandana , Boger Heather A. , Granholm Ann‐Charlotte , Rohrer Baerbel , Moore Alfred , Buhusi Mona , Gerhardt Greg A. , Hoffer Barry J. , Middaugh Lawrence D. 
Published: October 2008

AbstractGiven the established importance of glial cell line‐derived neurotrophic factor (GDNF) in maintaining dopaminergic neurotransmitter systems, the nigrostriatal system and associated behaviors of mice with genetic reduction of its high‐affinity receptor, GDNF receptor (GFR)α‐1 (GFRα‐1+/−), were compared with wild‐type controls. Motor activity and the stimulatory effects of a dopamine (DA) D1 receptor agonist (SKF 82958) were assessed longitudinally at 8 and 18 months of age. Monoamine concentrations and dopaminergic nerve terminals in the striatum and the number of dopaminergic neurons in the substantia nigra (SN) were assessed. The results support the importance of GFRα‐1 in maintaining normal function of the nigrostriatal dopaminergic system, with deficits being observed for GFRα‐1+/− mice at both ages. Motor activity was lower and the stimulatory effects of the DA agonist were enhanced for the older GFRα‐1+/− mice. DA in the striatum was reduced in the GFRα‐1+/− mice at both ages, and tyrosine hydroxylase‐positive cell numbers in the SN were reduced most substantially in the older GFRα‐1+/− mice. The combined behavioral, pharmacological probe, neurochemical and morphological measures provide evidence of abnormalities in GFRα‐1+/− mice that are indicative of an exacerbated aging‐related decline in dopaminergic system function. The noted deficiencies, in turn, suggest that GFRα‐1 is necessary for GDNF to maintain normal function of the nigrostriatal dopaminergic system. Although the precise mechanism(s) for the aging‐related changes in the dopaminergic system remain to be established, the present study clearly establishes that genetic reductions in GFRα‐1 can contribute to the degenerative changes observed in this system during the aging process.
Modulating activity in the motor cortex affects performance for the two hands differently depending upon which hemisphere is stimulated
Authors: Vines Bradley W. , Nair Dinesh , Schlaug Gottfried 
Published: October 2008

AbstractWe modulated neural excitability in the human motor cortex to investigate behavioral effects for both hands. In a previous study, we showed that decreasing excitability in the dominant motor cortex led to a decline in performance for the contralateral hand and an improvement for the ipsilateral hand; increasing excitability produced the opposite effects. Research suggests that the ipsilateral effects were mediated by interhemispheric inhibition. Physiological evidence points to an asymmetry in interhemispheric inhibition between the primary motor cortices, with stronger inhibitory projections coming from the dominant motor cortex. In the present study, we examined whether there is a hemispheric asymmetry in the effects on performance when modulating excitability in the motor cortex. Anodal and cathodal transcranial direct current stimulation were applied to the motor cortex of 17 participants, targeting the non‐dominant hemisphere on one day and the dominant hemisphere on another day, along with one sham session. Participants performed a finger‐sequence coordination task with each hand before and after stimulation. The dependent variable was calculated as the percentage of change in the number of correct keystrokes. We found that the effects of transcranial direct current stimulation depended upon which hemisphere was stimulated; modulating excitability in the dominant motor cortex significantly affected performance for the contralateral and ipsilateral hands, whereas modulating excitability in the non‐dominant motor cortex only had a significant impact for the contralateral hand. These results provide evidence for a hemispheric asymmetry in the ipsilateral effects of modulating excitability in the motor cortex and may be important for clinical research on motor recovery.
Progressive loss of PAX6, TBR2, NEUROD and TBR1 mRNA gradients correlates with translocation of EMX2 to the cortical plate during human cortical development
Authors: Bayatti Nadhim , Sarma Subrot , Shaw Christopher , Eyre Janet A. , Vouyiouklis Demetrius A. , Lindsay Susan , Clowry Gavin J. 
Published: October 2008

AbstractThe transcription factors Emx2 and Pax6 are expressed in the proliferating zones of the developing rodent neocortex, and gradients of expression interact in specifying caudal and rostral identities. Pax6 is also involved in corticoneurogenesis, being expressed by radial glial progenitors that give rise to cells that also sequentially express Tbr2, NeuroD and Tbr1, genes temporally downstream of Pax6. In this study, using in situ hybridization, we analysed the expression of EMX2, PAX6, TBR2, NEUROD and TBR1 mRNA in the developing human cortex between 8 and 12 postconceptional weeks (PCW). EMX2 mRNA was expressed in the ventricular (VZ) and subventricular zones (SVZ), but also in the cortical plate, unlike in the rodent. However, gradients of expression were similar to that of the rodent at all ages studied. PAX6 mRNA expression was limited to the VZ and SVZ. At 8 PCW, PAX6 was highly expressed rostrally but less so caudally, as has been seen in the rodent, however this gradient disappeared early in corticogenesis, by 9 PCW. There was less restricted compartment‐specific expression of TBR2, NEUROD and TBR1 mRNA than in the rodent, where the gradients of expression were similar to that of PAX6 prior to 9 PCW. The gradient disappeared for TBR2 by 10 PCW, and for NEUROD and TBR1 by 12 PCW. These data support recent reports that EMX2 but not PAX6 is more directly involved in arealization, highlighting that analysis of human development allows better spatio‐temporal resolution than studies in rodents.
Pavlovian fear conditioning as a behavioral assay for hippocampus and amygdala function: cautions and caveats
Authors: Maren Stephen 
Published: October 2008

AbstractPavlovian fear conditioning has become an important model for investigating the neural substrates of learning and memory in rats, mice and humans. The hippocampus and amygdala are widely believed to be essential for fear conditioning to contexts and discrete cues, respectively. Indeed, this parsing of function within the fear circuit has been used to leverage fear conditioning as a behavioral assay of hippocampal and amygdala function, particularly in transgenic mouse models. Recent work, however, blurs the anatomical segregation of cue and context conditioning and challenges the necessity for the hippocampus and amygdala in fear learning. Moreover, nonassociative factors may influence the performance of fear responses under a variety of conditions. Caution must therefore be exercised when using fear conditioning as a behavioral assay for hippocampal‐ and amygdala‐dependent learning.
Coastal Synechococcus metagenome reveals major roles for horizontal gene transfer and plasmids in population diversity
Authors: Palenik B. , Ren Q. , Tai V. , Paulsen I. T. 
Published: October 2008

SummaryThe extent to which cultured strains represent the genetic diversity of a population of microorganisms is poorly understood. Because they do not require culturing, metagenomic approaches have the potential to reveal the genetic diversity of the microbes actually present in an environment. From coastal California seawater, a complex and diverse environment, the marine cyanobacteria of the genus Synechococcus were enriched by flow cytometry‐based sorting and the population metagenome was analysed with 454 sequencing technology. The sequence data were compared with model Synechococcus genomes, including those of two coastal strains, one isolated from the same and one from a very similar environment. The natural population metagenome had high sequence identity to most genes from the coastal model strains but diverged greatly from these genomes in multiple regions of atypical trinucleotide content that encoded diverse functions. These results can be explained by extensive horizontal gene transfer presumably with large differences in horizontally transferred genetic material between different strains. Some assembled contigs showed the presence of novel open reading frames not found in the model genomes, but these could not yet be unambiguously assigned to a Synechococcus clade. At least three distinct mobile DNA elements (plasmids) not found in model strain genomes were detected in the assembled contigs, suggesting for the first time their likely importance in marine cyanobacterial populations and possible role in horizontal gene transfer.