bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quadriceps strength and volitional activation before and after total knee arthroplasty for osteoarthritis
Authors: Stevens Jennifer E. , Mizner Ryan L. , Snyder‐Mackler Lynn 
Published: April 2003

AbstractIntroduction: Patients with osteoarthritis (OA) of the knee have quadriceps weakness and arthrogenous muscle inhibition (AMI). While total knee arthroplasty (TKA) reliably reduces pain and improves function in patients with knee OA, quadriceps weakness persists after surgery. The purpose of this investigation was to assess contributions of AMI to quadriceps weakness before and after TKA and to assess the effect of pain on AMI.Methods: Twenty‐eight patients with unilateral, end‐stage, primary knee OA were tested an average of 10 days before and 26 days after TKA. The mean age at time of operation was 63 years (range 49–82 years). Measurements on the involved and uninvolved knees were performed using the burst‐superimposition technique, where supramaximal electrical stimulation is superimposed on a voluntary contraction. Knee pain during contraction was measured using a numeric rating scale.Results: The involved quadriceps were significantly weaker than the uninvolved prior to TKA (p < 0.05). Quadriceps strength decreased by 60% (p < 0.001) and activation decreased 17% (p < 0.001) after TKA. Changes in muscle activation accounted for 65% of the variability in the change in quadriceps strength (r2 = 0.65) (p < 0.001). Knee pain during muscle contraction accounted for a small, but significant portion of the change in voluntary activation (r2 = 0.22) (p = 0.006).Discussion: Exercise regimens that emphasize strong muscle contraction and clinical tools that facilitate muscle activation like biofeedback and neuromuscular electrical stimulation may be necessary to reverse the quadriceps activation failure and weakness in the patients with knee OA that worsens after TKA. The failure of current rehabilitation regimens to directly address activation deficits within the first months after surgery may explain the persistent quadriceps weakness in patients after TKA. © 2003 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Differential effects of static and dynamic compression on meniscal cell gene expression
Authors: Upton Maureen L. , Chen Jun , Guilak Farshid , Setton Lori A. 
Published: April 2003

AbstractCells of the meniscus are exposed to a wide range of time‐varying mechanical stimuli that may regulate their metabolic activity in vivo. In this study, the biological response of the meniscus to compressive stimuli was evaluated in vitro, using a well‐controlled explant culture system. Gene expression for relevant extracellular matrix proteins was quantified using real‐time RT‐PCR following a 24 h period of applied static (0.1 MPa compressive stress) or dynamic compression (0.08–0.16 MPa). Static and dynamic compression were found to differentially regulate mRNA levels for specific proteins of the extracellular matrix. Decreased mRNA levels were observed for decorin (∼︁2.1 fold‐difference) and type II collagen (∼︁4.0 fold‐difference) following 24 h of dynamic compression. Decorin mRNA levels also decreased following static compression (∼︁4.5 fold‐difference), as did mRNA levels for both types I (∼︁3.3 fold‐difference) and II collagen (∼︁4.0 fold‐difference). Following either static or dynamic compression, mRNA levels for aggrecan, biglycan and cytoskeletal proteins were unchanged. It is noteworthy that static compression was associated with a 2.6 fold‐increase in mRNA levels for collagenase, or MMP‐1, suggesting that the homeostatic balance between collagen biosynthesis and catabolism was altered by the mechanical stimuli. These findings demonstrate that the biosynthetic response of the meniscus to compression is regulated, in part, at the transcriptional level and that transcription of types I and II collagen as well as decorin may be regulated by common mechanical stimuli. © 2003 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
The postnatal development of the hypothalamic–pituitary–adrenal axis in the mouse
Authors: Schmidt M. , Enthoven L. , van der Mark M. , Levine S. , de Kloet E.R. , Oitzl M.S. 
Published: April 2003

AbstractThe main characteristic of the postnatal development of the stress system in the rat is the so‐called stress hypo‐responsive period (SHRP). Lasting from postnatal day (pnd) 4 to pnd 14, this period is characterized by very low basal corticosterone levels and an inability of mild stressors to induce an enhanced ACTH and corticosterone release. During the last years, the mouse has become a generally used animal in stress research, also due to the wide availability of genetically modified mouse strains. However, very few data are available on the ontogeny of the stress system in the mouse. This study therefore describes the postnatal ontogeny of peripheral and central aspects of the hypothalamic–pituitary–adrenal (HPA) axis in the mouse. We measured ACTH and corticosterone in blood and CRH, urocortin 3 (UCN3), mineralocorticoid receptor (MR) and glucocorticoid receptor (GR) transcripts in the brain at postnatal days 1, 2, 4, 6, 9, 12, 14 and 16. Our results show that we can subdivide the postnatal development of the HPA axis in the mouse in two phases. The first phase corresponds to the SHRP in the rat and lasts from right after birth (pnd 1) until pnd 12. Basal corticosterone levels were low and novelty exposure did not enhance corticosterone or ACTH levels. This period is further characterized by a high expression of CRH in the paraventricular nucleus (PVN) of the hypothalamus. Expression levels of GR in the hippocampus and UCN3 in the perifornical area are low at birth but increase significantly during the SHRP, both reaching the highest expression level at pnd 12. In the second phase, the mice have developed past the SHRP and were now exhibiting enhanced corticosterone basal levels and a response of ACTH and corticosterone to mild novelty stress. CRH expression was decreased significantly, while expression of UCN3 and GR remained high, with a small decrease at pnd 16. The expression of MR in the hippocampus was very dynamic throughout the postnatal development of the HPA axis and changed in a time and subregion specific manner. These results demonstrate for the first time the correlation between the postnatal endocrine development of the mouse and gene expression changes of central regulators of HPA axis function.
Is presidential cycle in security returns merely a reflection of business conditions?
Authors: Booth James R , Booth Lena Chua 
Published: April 2003

AbstractWe confirm previous findings that both large‐cap and small‐cap stock returns in the US exhibit a presidential cycle pattern, i.e. returns are significantly higher in the last 2 years than in the first 2 years of the presidential term. We attempt to examine if this presidential cycle pattern can be explained away by the traditional business cycle proxies, namely the term spread (TERM), dividend yield (D/P), and default spread (DEF). Our motivation arises from the political business cycle theory that monetary and fiscal measures undertaken by presidents are usually translated into the business cycle. We find that the presidential cycle has explanatory power beyond business conditions proxies shown to be important in explaining stock returns. Tests of slope parameters show that stock returns are less sensitive to only the D/P during the last 2 years of the presidential term. The presidential cycle effect prevails even after controlling for the party in power and the incumbent versus nonincumbent presidents.
Conformational states of the switch I region of Ha‐ras‐p21 in hinge residue mutants studied by fluorescence lifetime and fluorescence anisotropy measurements
Authors: Kuppens Steven , Hellings Mario , Jordens Jan , Verheyden Stefan , Engelborghs Yves 
Published: April 2003

AbstractThe hinge residues (Val29 and Ile36) of the switch I region (also known as the effector loop) of the Ha‐ras‐p21 protein have been mutated to glycines to accelerate the conformational changes typical for the effector loop. In this work, we have studied the influence of the combined mutations on the steady‐state structure of the switch I region of the protein in both the inactive GDP‐bound conformation as in the active GTP‐bound conformation. Here, we use the fluorescence properties of the single tryptophan residue in the Y32W mutant of Ha‐ras‐p21. This mutant has already been used extensively as a reference form of the protein. Reducing the size of the side chains of the hinge residues not only accelerates the conformational changes but also affects the steady‐state structures of the effector loop as indicated by the changes in the fluorescence properties. A thorough analysis of the fluorescence changes (quantum yield, lifetimes, etc.) proves that these changes are from a reshuffling between the rotamer populations of Trp. The population reshuffling is caused by the overall structural rearrangement along the switch I region. The effects are clearly more pronounced in the inactive GDP‐bound conformation than in the active GTP‐bound conformation. The effect of both mutations seems to be additive in the GDP‐bound state, but cooperative in the GTP‐bound state.
The catalytic mechanism of galactose mutarotase
Authors: Thoden James B. , Kim Jungwook , Raushel Frank M. , Holden Hazel M. 
Published: April 2003

AbstractGalactose mutarotase catalyzes the first step in normal galactose metabolism by catalyzing the conversion of β‐d‐galactose to α‐d‐galactose. The structure of the enzyme from Lactococcus lactis was recently solved in this laboratory and shown to be topologically similar to domain 5 of β‐galactosidase. From this initial X‐ray analysis, four amino acid residues were demonstrated to be intimately involved in sugar binding to the protein: His 96, His 170, Asp 243, and Glu 304. Here we present a combined X‐ray crystallographic and kinetic analysis designed to examine the role of these residues in the reaction mechanism of the enzyme. For this investigation, the following site‐directed mutant proteins were prepared: H96N, H170N, D243N, D243A, E304Q, and E304A. All of the structures of these proteins, complexed with either glucose or galactose, were solved to a nominal resolution of 1.95 Å or better, and their kinetic parameters were measured against d‐galactose, d‐glucose, l‐arabinose, or d‐xylose. From these studies, it can be concluded that Glu 304 and His 170 are critical for catalysis and that His 96 and Asp 243 are important for proper substrate positioning within the active site. Specifically, Glu 304 serves as the active site base to initiate the reaction by removing the proton from the C‐1 hydroxyl group of the sugar substrate and His 170 functions as the active site acid to protonate the C‐5 ring oxygen.
NON-ABELIAN GENERALIZATION OF ELECTRIC–MAGNETIC DUALITY — A BRIEF REVIEW
Authors: CHAN HONG-MO , TSOU SHEUNG TSUN 
Published: April 2003

A loop space formulation of Yang–Mills theory highlighting the significance of monopoles for the existence of gauge potentials is used to derive a generalization of electric–magnetic duality to the non-Abelian theory. The result implies that the gauge symmetry is doubled from SU (N) to [Formula: see text], while the physical degrees of freedom remain the same, so that the theory can be described in terms of either the usual Yang–Mills potential Aμ(x) or its dual Ãμ(x). Non-Abelian "electric" charges appear as sources of Aμ but as monopoles of Ãμ, while their "magnetic" counterparts appear as monopoles of Aμ but sources of Ãμ. Although these results have been derived only for classical fields, it is shown for the quantum theory that the Dirac phase factors (or Wilson loops) constructed out of Aμ and Ãμ satisfy the 't Hooft commutation relations, so that his results on confinement apply. Hence one concludes, in particular, that since colour SU (3) is confined, dual colour [Formula: see text] is broken. Such predictions can lead to many very interesting physical consequences, which are explored in a companion paper.
Electrophysiological Mapping and Histological Examinations of the Swine Atrium with Sustained (≥24 h) Atrial Fibrillation: A Suitable Animal Model for Studying Human Atrial Fibrillation
Authors: Lin Jiunn-Lee , Lai Ling-Ping , Lin Chih-Shen , Du Chao-Cheng , Wu Tsu-Juey , Chen Shih-Ping , Lee Wen-Chuan , Yang Ping-Cheng , Tseng Yung-Zu , Lien Wen-Pin , Huang Shoei K. Stephen 
Published: April 2003

<i>Objectives:</i> Interventional elimination of chronic persistent atrial fibrillation (AFib) remains difficult. An animal model mimicking the clinical situation is important. <i>Methods and Results:</i> Twenty-five adult pigs were implanted with a high-speed atrial pacemaker. After continuous pacing at 600 bpm for 6 weeks, 20 (91%) of the 22 survivals developed sustained AFib lasting for at least 24 h. Epicardial dense mapping revealed multiple coexisting reentrant wavelets in the left and the right atrium (LA and RA, respectively; 10.6 ± 2.9 vs. 7.6 ± 2.4 wavelets/cm<sup>2</sup>/s; p < 0.002). The mean local A-A intervals were 87.2 ± 14.6 ms in the LA and 103.3 ± 19.0 ms in the RA (p < 0.0002). Acute termination of sustained AFib was successful in 3 of the 5 pigs by propafenone, but in none of the 6 by <i>dl</i>-sotalol. Epicardial cryothermal ablation failed to terminate any AFib by compartmentalization of the RA free wall alone (4 pigs) or together with the LA appendage (4 pigs). Electron microscopic examination demonstrated diffuse perinuclear myolysis, myofibrillar fragmentation and mitochondrial crystal disruption in the atrium. <i>Conclusions:</i> Pacing-induced sustained AFib (≧24 h) in adult pigs is a feasible and efficient animal model with electrophysiological and histological characteristics closely similar to those seen in humans.
Comparison of a 48-Hour Infusion of 5-Fluorouracil without Folinic Acid with 24-Hour Folinic Acid/5-Fluorouracil in Patients with Metastatic Colorectal Cancer Refractory to Bolus Folinic Acid/5-Fluorouracil
Authors: Moehler Markus , Gutzler Frank , Steinmann Silke , Boehme Michael , Raeth Ulrich , Stremmel Wolfgang , Galle Peter R. , Rudi Jochen 
Published: April 2003

<i>Background:</i> Out of various high-dose 5-fluorouracil (5-FU) regimens given with or without folinic acid (FA), the optimal 5-FU schedule has still to be defined as treatment for metastatic colorectal cancer (CRC). Consequently, we compared toxicity, response and survival following two FA/5-FU regimens in 55 CRC patients refractory to bolus FA/5-FU. <i>Methods:</i> Twenty-eight patients (group A) received 5-FU (60 mg/kg body weight) for 48 h, and 27 (group B) received 2-hour infusions of FA (500 mg/m<sup>2</sup>) and 24-hour infusions of 5-FU (2,600 mg/m<sup>2</sup>) until disease progression. <i>Results:</i> Both groups were adequately matched with respect to patient characteristics. While overall toxicities were rare, hand-foot syndrome was more common in A. Tumor control was achieved in 57 and 44%, for A and B, respectively. Survival times were 16 months in A and 9 months in B. <i>Conclusions:</i> Since both 5-FU infusion protocols showed equivalent palliative effects, FA may be questioned in second-line 5-FU regimens.
Treatment with Simvastatin in Patients with Alzheimer’s Disease Lowers Both α- and β-Cleaved Amyloid Precursor Protein
Authors: Sjögren Magnus , Gustafsson Kina , Syversen Steinar , Olsson Annika , Edman Åke , Davidsson Pia , Wallin Anders , Blennow Kaj 
Published: April 2003

We investigated the clinical and biological effects of cholesterol-lowering treatment with a statin in 19 patients with Alzheimer’s disease. They received simvastatin 20 mg/day for 12 weeks in an open trial. Primary efficacy parameters were the changes after 12 weeks in the cerebrospinal fluid (CSF) levels of β-amyloid<sub>42</sub> (Aβ<sub>42</sub>), α-secretase-cleaved amyloid precursor protein (α-sAPP), β-secretase-cleaved APP (β-sAPP), tau, phospho-tau and the plasma levels of Aβ<sub>42</sub>. A secondary efficacy parameter was the change in the Alzheimer’s Disease Assessment Scale-Cognition (ADAS-cog) score. After 12 weeks, CSF α-sAPP and CSF β-sAPP were significantly reduced (p < 0.001), but the CSF levels of tau, phospho-tau, Aβ<sub>42</sub> and the plasma levels of Aβ<sub>42</sub> were unchanged. The ADAS-cog score was slightly increased (p < 0.05). The results suggest that simvastatin acts directly on the processing of APP by inhibiting both the α- and the β-secretase pathways.
Multilayer Primary Epithelial Cell Culture from Bovine Conjunctiva as a Model for in vitro Toxicity Tests
Authors: Civiale Claudine , Paladino Grazia , Marino Clara , Trombetta Francesco , Pulvirenti Teodoro , Enea Vincenzo 
Published: April 2003

<i>Objective:</i> The purpose of this study was to obtain a primary cell culture of bovine origin similar to the conjunctiva in terms of morphology and cell types, which could be of use for in vitro toxicity studies. <i>Methods:</i> After separation from the stroma by enzymatic treatment, conjunctival epithelial cells were dissociated and plated onto collagen-coated Transwell<sup>®</sup> filters (1.13 cm<sup>2</sup> area). One group of plates was maintained in immersion and another was cultured under air-lifted conditions. Anti-epithelial keratin antibodies (AE1/AE3, K4) and antidesmoplakin 1 and 2 were used to characterize the cells by indirect immunofluorescence. The cell layer was examined after histological processing of the Transwell filter. Ultrastructural analysis was carried out by scanning electron microscopy (SEM). The bioelectric parameters transepithelial electrical resistance (TEER), potential difference (PD), short circuit current and paracellular permeability profile of carboxyfluorescein were monitored as indices of the functional characteristics of these cultures. Cytotoxicity was evaluated on morphological and functional (TEER) grounds after treating the cultures with several test substances. <i>Results:</i> Morphological studies showed pure and homogeneous cell cultures. In the SEM analysis, we observed contiguous polygonal cells with numerous short microvilli, a characteristic proportion of light, medium and dark cells and a sparse population of rounded PAS-positive cells, i.e. resembling goblet cells. Air-lifted cultures also showed a tissue-like cellular organization (8–9 layers). Immersion cultures reached a maximum TEER value of around 2.95 kΩ·cm<sup>2</sup> 7 days after plating while in air-lifted cultures TEER peaked up to 5.59 kΩ·cm<sup>2</sup> 11 days after plating. With regard to the use of bovine conjunctival epithelial cells (BCECs) for cytotoxicity screening, the system responded finely to the insults and yielded morphological and functional results in accordance with data obtained in vivo. <i>Conclusions:</i> BCECs reproduce cell morphology and differentiation of the original tissue and should prove a useful tool for initial studies of drug toxicity.
Hydrogel Tissue Adhesive for Sealing Corneal Incisions
Authors: Kalaycı Defne , Fukuchi Toshio , Edelman Peter G. , Sawhney Amarpreet S. , Mehta Mehul C. , Hirose Tatsuo 
Published: April 2003

The purpose of the study was to assess the efficacy of a newly developed hydrogel tissue adhesive for sealing corneal incisions in ex vivo rabbit eyes. Simple through-and-through central linear corneal incisions measuring 1–5 mm were created in enucleated rabbit eyes. As controls, the leaking pressures were measured immediately after the incisions had been made. Afterwards, the incisions were sealed with hydrogel adhesive in group 1 and with a single 10-0 nylon suture in group 2. The leaking pressure of each incision was measured after the wounds had been sealed in both groups. The leaking pressures of the controls and the sealed incisions were compared for statistical significance using the Wilcoxon signed rank test. The difference between the leaking pressures before and after sealing the incisions in groups 1 and 2 were compared using the Mann-Whitney rank sum test. The leaking pressures were significantly higher after sealing in both groups 1 and 2 compared to the controls for all incision sizes. The differences in the leaking pressures before and after adhesive application were higher than before and after suturing in all incision sizes. The differences were all statistically significant except for the 1-mm incisions. We conclude that the hydrogel glue has the potential to be used for sealing corneal incisions measuring up to 5 mm.
GH Values after Clonidine Stimulation Measured by Immunofluorometric Assay in Normal Prepubertal Children and GH-Deficient Patients
Authors: Silva Eveline G.P. , Slhessarenko Natasha , Arnhold Ivo J.P. , Batista Marcelo C. , Estefan Vivian , Osorio Maria G.F. , Marui Suemi , Mendonca Berenice B. 
Published: April 2003

<i>Objective:</i> To establish the cut-off values of GH measured by immunofluorometric assay, a more sensitive and specific assay, in normal prepubertal children and compare their values with those of proven GH-deficient patients. <i>Methods:</i> 30 normal children (20 males) and 26 patients with known causes of GH deficiency were submitted to the clonidine test and their GH values were compared. A powdered clonidine tablet (0.1 mg/m<sup>2</sup>) was given orally and blood samples for GH measurements were drawn at times –30, 0, 60, 90 and 120 min. <i>Results:</i> GH peak values presented a wide variation ranging from 1.7 to 25 µg/l (mean ± SD = 12.87 ± 5.8 µg/l) in the normal group. The cut-off values for the 5th and 10th percentiles of the distribution curve were 3.3 and 5.5 µg/l, respectively. In the GH deficiency group, maximum GH levels after clonidine stimulation ranged from <0.1 to 2.1 µg/l (0.56 ± 0.58 µg/l). <i>Conclusions</i>: The cut-off values obtained with the immunofluorometric method are lower than the ones obtained by radioimmunoassay. We suggest a cut-off value of 3.3 µg/l (5th percentile) that ensures 100% of sensitivity along with 93% of specificity to exclude the diagnosis of GH deficiency when using this immunofluorometric method.
Characterization of Empathy Deficits following Prefrontal Brain Damage: The Role of the Right Ventromedial Prefrontal Cortex
Authors: Shamay-Tsoory S. G. , Tomer R. , Berger B. D. , Aharon-Peretz J. 
Published: April 2003

Abstract
Impaired empathic response has been described in patients following brain injury, suggesting that empathy may be a fundamental aspect of the social behavior disturbed by brain damage. However, the neuroanatomical basis of impaired empathy has not been studied in detail. The empathic response of patients with localized lesions in the prefrontal cortex (n = 25) was compared to responses of patients with posterior (n = 17) and healthy control subjects (n = 19). To examine the cognitive processes that underlie the empathic ability, the relationships between empathy scores and the performance on tasks that assess processes of cognitive flexibility, affect recognition, and theory of mind (TOM) were also examined. Patients with prefrontal lesions, particularly when their damage included the ventromedial prefrontal cortex, were significantly impaired in empathy as compared to patients with posterior lesions and healthy controls. However, among patients with posterior lesions, those with damage to the right hemisphere were impaired, whereas those with left posterior lesions displayed empathy levels similar to healthy controls. Seven of nine patients with the most profound empathy deficit had a right ventromedial lesion. A differential pattern regarding the relationships between empathy and cognitive performance was also found: Whereas among patients with dorsolateral prefrontal damage empathy was related to cognitive flexibility but not to TOM and affect recognition, empathy scores in patients with ventromedial lesions were related to TOM but not to cognitive flexibility. Our findings suggest that prefrontal structures play an important part in a network mediating the empathic response and specifically that the right ventromedial cortex has a unique role in integrating cognition and affect to produce the empathic response.