bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pre‐steady‐state kinetic studies of rat kidney γ‐glutamyl transpeptidase confirm its ping‐pong mechanism
Authors: Keillor Jeffrey W. , Ménard Annie , Castonguay Roselyne , Lherbet Christian , Rivard Caroline 
Published: May 2004

AbstractThe enzyme γ‐glutamyl transpeptidase (GGT) is implicated in cellular detoxification, the biosynthesis of leukotrienes and control of the physiological concentration of glutathione. It also plays important roles in Parkinson's disease, diabetes, apoptosis inhibition and cancer drug resistance. It catalyses the breakdown of its in vivo substrate, glutathione, by cleaving the amide bond between the γ‐glutamyl and the cysteinylglycine moieties. Threonine is proposed to act as the nucleophile of GGT in the formation of the γ‐glutamyl acyl enzyme intermediate during the acylation step. The γ‐glutamyl moiety is then transferred to a primary amine acceptor substrate (an amino acid or dipeptide) or to a water molecule, to form a compound containing a new isopeptide bond or glutamate in the transamidation or hydrolysis reactions, respectively. In spite of the importance of the role of GGT in human physiology, there is a lack of information about the mechanisms of its catalytic reactions, and in particular the nature of the intermediate formed during the acylation step. In order to gain insight into the formation of the acyl enzyme intermediate, different D‐γ‐glutamylanilides substituted in the para position with electron‐withdrawing and electron‐donating groups were used as donor substrates under conditions where water served as acceptor substrate. A Hammett plot with a slope of zero was obtained for the steady‐state hydrolysis reaction for which deacylation is the rate‐ limiting step. To confirm the ping‐pong mechanism, pre‐steady‐state kinetics of this reaction were then performed with the donor substrate D‐γ‐glutamyl‐p‐nitroanilide, which liberates the chromophore p‐nitroaniline. Experiments using a stopped‐ flow spectrometer and a rapid mix–quench apparatus gave biphasic traces with a burst up to ∼65 ms, the amplitude of which corresponds well with the concentration of the enzyme. These burst kinetics were also observed in the presence of L‐methionine at concentrations ∼15‐fold below its KM value, where deacylation would still be rate limiting. These observations are consistent with the formation of an intermediate during the rapid acylation step and support the modified ping‐pong mechanism proposed for GGT‐ mediated hydrolysis and aminolysis. Copyright © 2004 John Wiley & Sons, Ltd.
Hollow microstructures of polypyrrole doped by poly(styrene sulfonic acid)
Authors: Qu Liangti , Shi Gaoquan 
Published: May 2004

AbstractMicrostructures with hollow interiors, such as microspheres, microcrocks, microbowls, and micropumpkins, were prepared through the direct electrochemical oxidation of pyrrole in an aqueous solution of poly(styrene sulfonic acid) (PSSA). Scanning electron microscopy demonstrated that the microstructures possessed hollow interiors. The addition of polymeric doping ions made the skins of the microstructures very smooth, and several novel structures were observed. The morphology of the microstructures was simply modulated through changes in the electrochemical conditions. Raman and Fourier transform infrared characterizations indicated that the microstructures were made of conductive polypyrrole (PPy) doped by polymeric anions of poly(styrene sulfonate), and X‐ray diffraction showed that the microstructures were amorphous. Thermogravimetric analysis indicated that PPy–PSSA composite films with microstructures had higher thermal stability than pure PPy, PPy‐coated PSSA microspheres, and naphthalene sulfonic acid doped PPy microstructures. Furthermore, PPy–PSSA composite films with microstructures showed cation‐exchange behavior during the redox process in aqueous solutions of sodium dodecyl benzenesulfonate. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3170–3177, 2004
A Double Gaussian Beam Method for the Determination of Particle Size, Direction and Velocity
Authors: Castagner Jean Luc , Jones Alan R. 
Published: May 2004

AbstractThis paper describes a technique aimed at measuring particle size by light scattering from gaussian laser beams. The uncertainties in illumination due to the beam shape are avoided by determination of the direction and velocity. The method, which we arbitrarily called the Two Beam System (TBS), uses a simple birefringent prism to separate the incident laser beam into two orthogonally polarised overlapping parallel beams. The relative delay and amplitudes of the intensities scattered out of the orthogonal polarisations are indicative of the particle direction and velocity. Having obtained the direction of travel of the particle, its size is then obtained from the scattered intensity using Mie theory.
CNS involvement in Fabry disease: Clinical and imaging studies before and after 12 months of enzyme replacement therapy
Authors: Jardim L. , Vedolin L. , Schwartz I. V. D. , Burin M. G. , Cecchin C. , Kalakun L. , Matte U. , Aesse F. , Pitta‐Pinheiro C. , Marconato J. , Giugliani R. 
Published: May 2004

AbstractSummary: We report the clinical and radiological central nervous system (CNS) findings of 8 Fabry disease patients, before (8/8) and after (7/8) 12 months of enzyme replacement therapy (ERT) with agalsidase‐alpha. Eight biochemically proven Fabry disease patients (from four families) were included. Patients were evaluated at baseline and at regular intervals during 12 months of ERT. Evaluations included a thorough, standardized neurological examination, and magnetic resonance imaging (MRI) and angiography (MRA). Brain proton magnetic resonance spectroscopy (MRS) was also performed in 5/8 patients. The presence and location of grey‐ and white‐matter lesions, the presence of vascular occlusion or ectasia on MRA and the metabolite ratios on MRS were determined, as well as their relation to age, symptoms and neurological examination. Neurological examination showed few abnormalities in these patients: scores varied (on a 0–100 scale) from zero to 5, at baseline and in the 12th month of ERT. The most consistent findings on MRI were asymmetric, widespread patterns of deep white‐matter (WM) lesions, hyperintense on T2 and FLAIR‐weighted images, found in 4/8 patients at baseline, predominantly in frontal and parietal lobes. These lesions did not correlate with other clinical variables, although there was a trend towards an association of the lesions with age and hearing loss. The youngest patient with MRI lesions was 24 years old. After 12 months of ERT, MRI was normal in 3/7, showed the same WM lesions in 2/7, and showed worsening of WM lesions in 2/7 patients (from the same family). Abnormal MRS metabolite ratios were detected at baseline in 4/5 patients. While neurological examination remained almost normal during the 12 months of ERT, new small‐vessel CNS involvement still appeared in 2/7 patients. We do not know why ERT was not able to prevent this in these two related male patients. This could be due either to their older ages (46 and 36 years), or to a more pathogenic mutation. We conclude that MRI was more sensitive than neurological examination in detecting CNS involvement and progression in Fabry disease in the time interval studied.
The origin of Guideline Daily Amounts and the Food Standards Agency's guidance on what counts as ‘a lot’ and ‘a little’
Authors: Rayner Mike , Scarborough Peter , Williams Carol 
Published: May 2004

AbstractObjective:This paper provides the rationale for the Guideline Daily Amounts (GDAs) for fat, saturated fat and other nutrients that appear on food labels in the UK. These GDAs are provided voluntarily by manufacturers and retailers and were developed to help people make better use of nutrition labelling – the format of which is prescribed by the European Union's nutrition labelling directive. The paper also describes the basis to some Rules of Thumb for what counts as ‘a lot’ or ‘a little’ of fat, saturated fat and other nutrients, in an individual food.Design:The paper gives the background to, and purpose of, the GDAs and Rules of Thumb and explains how they were calculated. It briefly describes their subsequent usage by food producers and others.Results:Both GDAs and the Rules of Thumb first appeared in a leaflet developed by the authors and published in 1996 by the Ministry of Agriculture, Fisheries and Food. GDAs for fat, saturated fat and energy were adopted subsequently by the Institute of Grocery Distribution and then by many retailers and some manufacturers. The Rules of Thumb for fat, saturated fat, sugar and sodium have recently been republished in some leaflets published by the Food Standards Agency in the UK.Conclusions:GDAs and Rules of Thumb may provide useful ways of helping consumers make sense of nutrition labelling. The current GDAs and the Rules of Thumb could usefully be updated in the light of recent developments.
Anthropometry of women of childbearing age in Morocco: body composition and prevalence of overweight and obesity
Authors: Belahsen Rekia , Mziwira Mohamed , Fertat Fatima 
Published: May 2004

AbstractObjective:To determine the prevalence of obesity and body fat distribution of Moroccan women of childbearing age, using a panel of anthropometric measurements.Design and setting:A cross-sectional survey conducted in 1995 in an agricultural community, El Jadida province of Morocco. Weight, height, waist and hip circumferences and triceps, biceps, subscapular and supra-iliac skinfold thicknesses were measured. Body mass index (BMI), waist/hip ratio (WHR), sum of all and sum of trunk skinfold thicknesses were determined.Subjects:In total, 1269 women aged 15–49 years from urban and rural areas were surveyed.Results:The means of all anthropometric measurements including body fat were higher in urban than in rural women and increased with age. Trunk fat contributed 50% of total fat. Globally, 4.7% of women were underweight (BMI < 18.5 kg m−2), 35.2% were overweight or obese (BMI ≥ 25 kg m−2), 10.1% were obese (BMI ≥ 30 kg m−2) and 16.8% had central obesity (WHR > 0.85). The prevalence of overweight and obesity was higher in the urban than in the rural area. Underweight prevalence decreased with age, whereas that of overweight and obesity increased. All anthropometric parameters adjusted for age increased with the increase of BMI and WHR.Conclusions:Although undernutrition is still prevalent, there is an alarming prevalence of overweight and obesity in Moroccan women of childbearing age. The results indicate a shift in this country from the problem of dietary deficiency to the problem of dietary excess, and alert one to the necessity of establishing an intervention to prevent obesity-related diseases. It is necessary to address which of the anthropometric variables studied here is the best predictor of obesity-related diseases in this population.
Cerebrospinal Fluid Leak Prevention After Translabyrinthine Removal of Vestibular Schwannoma
Authors: Khrais Tarek H. , Falcioni Maurizio , Taibah Abdelkader , Agarwal Manoj , Sanna Mario 
Published: May 2004

AbstractObjectives/Hypothesis: The purpose of the report was to present an update on the authors' results for prevention and management of cerebrospinal fluid (CSF) leak after translabyrinthine approach for vestibular schwannoma.Study Design: Retrospective case review.Methods: The study was conducted at Gruppo Otologico (Piacenza, Italy), a tertiary referral center for neurotology and skull base surgery. In all, 710 patients underwent translabyrinthine approach for the removal of vestibular schwannoma at that institution between April 1987 and December 2002. The medical records were retrospectively reviewed to identify tumor size, the incidence of postoperative CSF leak, and its treatment.Results: The overall rate of CSF leak was 1.4%.Conclusion: The use of proper surgical technique minimizes the risk of CSF leak. Study results show that the continued application of the authors' proposed preventive measures resulted in the maintenance of a low rate of CSF leak. Immediate management of CSF fistulae helps prevent meningitis.
Association Between Birth Control Pills and Voice Quality
Authors: Amir Ofer , Kishon‐Rabin Liat 
Published: May 2004

AbstractObjectives/Hypothesis: The objective was to extend our knowledge of the effect of birth control pills on voice quality in women based on various acoustic measures.Study Design: A longitudinal comparative study of 14 healthy young women over a 36‐ to 45‐day period.Methods: Voices of seven women who used birth control pills and seven women who did not were recorded repeatedly approximately 20 times. Voice samples were analyzed acoustically, using an extended set of frequency perturbation parameters (jitter, relative average perturbation, pitch period perturbation quotient), amplitude perturbation parameters (shimmer, amplitude average perturbation quotient), and noise indices (noise‐to‐harmonics ratio, voice turbulence index).Results: Voice quality and stability were found to be better among the women who used birth control pills. Lower values were found for all acoustic measures with the exception of voice turbulence index. Results also provided preliminary indication for vocal changes associated with the days preceding ovulation.Conclusion: In contrast to the traditional view of oral contraceptives as a risk factor for voice quality, and in keeping with the authors' previous work, the data in the present study showed that not only did oral contraceptives have no adverse effect on voice quality but, in effect, most acoustic measures showed improved voice quality among women who used the birth control pill. The differences in the noise indices between groups may also shed light on the nature of the effect of sex hormones on vocal fold activity. It was suggested that hormonal fluctuations may have more of an effect on vocal fold regulation of vibration than on glottal adduction.
Torsional fatigue and endurance limit of a size 30 .06 ProFile rotary instrument
Authors: Best S. , Watson P. , Pilliar R. , Kulkarni G. G. K. , Yared G. 
Published: May 2004

AbstractAim  To evaluate the torsional cyclic fatigue characteristics and specifically the endurance limit (EL) of a nickel–titanium rotary instrument.Methodology  Size 30 .06 taper ProFile instruments were evaluated. The equipment was assembled according to the ANSI/ADA Specification No. 28. The motor was programmed to repeatedly rotate to a selected deflection angle (DA) and then return to zero (cycle). Testing started at 200° and was continued at decreasing angles until 106 cycles were reached without instrument fracture. Ten instruments were tested at each DA. The mean log number of cycles to fracture and standard deviation were determined for each DA at which fracture occurred. The DA at which 106 cycles were reached without instrument fracture corresponded by definition to the EL. Analysis of variance and pairwise comparisons using Duncan's multiple range test were performed to detect significant differences among the mean log number of cycles of the different DA. Significance was determined at the 95% confidence level.Results  Instruments cycled at larger DA consistently demonstrated fewer cycles to fracture than those cycled at smaller DA. The differences among the mean log number of cycles of the different DA were statistically significant (P < 0.001). Cycles of 106 were completed without instrument fracture at 2.5°.Conclusions  A torsional fatigue profile was generated for a specific NiTi rotary instrument. The EL was 2.5°.
Variation in lipid A structure in the pathogenic yersiniae
Authors: Rebeil Roberto , Ernst Robert K. , Gowen Brian B. , Miller Samuel I. , Hinnebusch B. Joseph 
Published: May 2004

SummaryImportant pathogens in the genus Yersinia include the plague bacillus Yersinia pestis and two enteropathogenic species, Yersinia pseudotuberculosis and Yersinia enterocolitica. A shift in growth temperature induced changes in the number and type of acyl groups on the lipid A of all three species. After growth at 37°C, Y. pestis lipopolysaccharide (LPS) contained the tetra‐acylated lipid IVA and smaller amounts of lipid IVA modified with C10 or C12 acyl groups, Y. pseudotuberculosis contained the same forms as part of a more heterogeneous population in which lipid IVA modified with C16:0 predominated, and Y. enterocolitica produced a unique tetra‐acylated lipid A. When grown at 21°C, however, the three yersiniae synthesized LPS containing predominantly hexa‐acylated lipid A. This more complex lipid A stimulated human monocytes to secrete tumour necrosis factor‐α, whereas the lipid A synthesized by the three species at 37°C did not. The Y. pestis phoP gene was required for aminoarabinose modification of lipid A, but not for the temperature‐dependent acylation changes. The results suggest that the production of a less immunostimulatory form of LPS upon entry into the mammalian host is a conserved pathogenesis mechanism in the genus Yersinia, and that species‐specific lipid A forms may be important for life cycle and pathogenicity differences.
Identification of novel dominant INO2 c mutants with an Opi– phenotype
Authors: Gardenour Kyle R. , Levy Jamie , Lopes John M. 
Published: May 2004

SummaryThe INO2 gene of Saccharomyces cerevisiae is required for derepression of the phospholipid biosynthetic genes in response to inositol depletion. Conversely, the OPI1 gene is required for repression in response to inositol supplementation. Results of an in vitro assay have led to a model in which Opi1p interacts with Ino2p. However, there is no in vivo evidence to support this model. Additionally, most of the previously isolated ino2 mutants offer little insight into this model. Here, we report the isolation of a new class of dominant mutations in the INO2 gene, which yield constitutive expression of a target gene (i.e. an Opi– mutant phenotype). Two mutations reside in a region of the Ino2p required for interaction with Opi1p in vitro. Three other mutations are at the amino‐terminus in a transcriptional activation domain.
Oligomeric structure of the Bacillus subtilis cell division protein DivIVA determined by transmission electron microscopy
Authors: Stahlberg H. , Kutejová E. , Muchová K. , Gregorini M. , Lustig A. , Müller S. A. , Olivieri V. , Engel A. , Wilkinson A. J. , Barák I. 
Published: May 2004

SummaryDivIVA from Bacillus subtilis is a bifunctional protein with distinct roles in cell division and sporulation. During vegetative growth, DivIVA regulates the activity of the MinCD complex, thus helping to direct cell division to the correct mid‐cell position. DivIVA fulfils a quite different role during sporulation in B. subtilis when it directs the oriC region of the chromosome to the cell pole before asymmetric cell division. DivIVA is a 19.5 kDa protein with a large part of its structure predicted to form a tropomyosin‐like α‐helical coiled‐coil. Here, we present a model for the quaternary structure of DivIVA, based on cryonegative stain transmission electron microscopy images. The purified protein appears as an elongated particle with lateral expansions at both ends producing a form that resembles a ‘doggy‐bone’. The particle mass estimated from these images agrees with the value of 145 kDa measured by analytical ultracentrifugation suggesting 6‐ to 8‐mers. These DivIVA oligomers serve as building blocks in the formation of higher order assemblies giving rise to strings, wires and, finally, two‐dimensional lattices in a time‐dependent manner.
Acute renal failure – definition, outcome measures, animal models, fluid therapy and information technology needs: the Second International Consensus Conference of the Acute Dialysis Quality Initiative (ADQI) Group
Authors: Bellomo Rinaldo , Ronco Claudio , Kellum John A , Mehta Ravindra L , Palevsky Paul ,   the ADQI workgroup
Published: May 2004

Abstract
Introduction
There is no consensus definition of acute renal failure (ARF) in critically ill patients. More than 30 different definitions have been used in the literature, creating much confusion and making comparisons difficult. Similarly, strong debate exists on the validity and clinical relevance of animal models of ARF; on choices of fluid management and of end-points for trials of new interventions in this field; and on how information technology can be used to assist this process. Accordingly, we sought to review the available evidence, make recommendations and delineate key questions for future studies.

Methods
We undertook a systematic review of the literature using Medline and PubMed searches. We determined a list of key questions and convened a 2-day consensus conference to develop summary statements via a series of alternating breakout and plenary sessions. In these sessions, we identified supporting evidence and generated recommendations and/or directions for future research.

Results
We found sufficient consensus on 47 questions to allow the development of recommendations. Importantly, we were able to develop a consensus definition for ARF. In some cases it was also possible to issue useful consensus recommendations for future investigations. We present a summary of the findings. (Full versions of the six workgroups' findings are available on the internet at http://www.ADQI.net)

Conclusion
Despite limited data, broad areas of consensus exist for the physiological and clinical principles needed to guide the development of consensus recommendations for defining ARF, selection of animal models, methods of monitoring fluid therapy, choice of physiological and clinical end-points for trials, and the possible role of information technology.
Hypoxia-Inducible Factor-1 Transactivates Transforming Growth Factor-β3 in Trophoblast
Authors: Nishi Hirotaka , Nakada Toshihide , Hokamura Mitsuyasu , Osakabe Yumi , Itokazu Osamu , Huang L. Eric , Isaka Keiichi 
Published: May 2004

AbstractHypoxia occurs during the development of placenta in the first trimester and is implicated in trophoblast differentiation. Intervillous blood flow increases after 10 wk of gestation and results in exposure of trophoblast cells to oxygen. Before this time, low oxygen appears to prevent trophoblast differentiation toward an invasive phenotype. The oxygen-regulated early events of trophoblast differentiation are mediated by TGF-β3. TGF-β3 plays a vital role in trophoblast differentiation, and its overexpression can be found in preeclamptic placenta. We sought to determine the mechanism of TGF-β3 expression through hypoxia-inducible factor (HIF)-1. We show that HIF-1α and TGF-β3 are overexpressed in preeclamptic placenta. Hypoxia not only transactivates the TGF-β3 promoter activity but also enhances endogenous TGF-β3 expression. Using the TGF-β3 promoter deletion mutants, we show that the region between −90 and −60, which contains a putative HIF-1 consensus motif, is crucial for HIF-1-mediated transactivation. Electrophoretic mobility shift assays show that HIF-1 binds to the oligonucleotide containing the HIF-1 motif. Also, introduction of an antisense oligonucleotide for HIF-1 diminishes TGF-β3 expression during hypoxia, indicating that the up-regulation of TGF-β3 by hypoxia is mediated through HIF-1. Our results provide evidence that regulation of TGF-β3 promoter activity by HIF-1 represents a mechanism for trophoblast differentiation during hypoxia.