bluuebunny/crossref_metadata_2025_split huggingface dataset:
Developmental changes of aminopeptidase activity in the cortex of the cat brain
Authors: Martínez‐Millán L. , de Gandarias J.M. , Irazusta J. , Echevarría E. , Casis L. 
Published: April 2003

AbstractAminopeptidase activity has been proposed as a candidate regulator of the degradation of several neuroactive peptides. In this paper, possible changes in Lys‐, Arg‐, Asp‐ and Tyr‐aminopeptidase activities in the cat brain neocortex (frontal, parietal, area 17 and areas 18 and 19 as a whole) were examined during two of the first stages of the critical developmental period (15 and 30 days postbirth). Aminopeptidase activities were studied by measuring the rate of hydrolysis of the artificial substrates Lys‐, Arg‐, Asp‐ and Tyr‐2‐naphthylamides (fluorimetrically detected in triplicate). Lys‐ and Argaminopeptidase activities do not show significant changes between the first the second stage in any of the cortical regions assayed. On the contrary, in all the cortical structures, activity with Tyr‐2‐naphthylamide shows significant increase with age. In contrast, the activity of Asp‐aminopeptidase shows significant decreases on the 30th day (except in area 17). It is suggested that these activities play a part in the neurochemical changes that take place during cat brain maturation.
Expression of NCAM mRNA and polypeptides in aging rat brain
Authors: Linnemann D. , Gaardsvoll H. , Olsen M. , Bock E. 
Published: April 2003

AbstractIn aging brain, degenerative as well as compensatory regenerative processes are believed to occur. The neural cell adhesion molecule NCAM is involved in developmental and regenerative processes in the brain. However, the role of NCAM in aging brain has not been characterized. In this study, the expression of NCAM mRNAs and polypeptides was investigated in aging rat brain. The 7.4 and 6.7 kb NCAM mRNAs were selectively downregulated during postnatal development, and the 5.2 and 2.9 kb NCAM mRNAs were upregulated. However, from postnatal day 40 to old age no change in NCAM mRNA classes was observed. The fraction of NCAM mRNA containing the VASE exon increased postnatally but remained stable during adult life. VASE, which is believed to modulate the binding capacity, seemed to be relatively more abundant in the 7.4 and 6.7 kb NCAM mRNAs, encoding transmembrane NCAM forms, than in the 5.2 and 2.9 kb NCAM mRNAs, coding for glycosyl phosphatidylinositol (GPI) linked NCAM. Conversely, insertion of exons a and AAG between exons 12 and 13, a region containing two fibronectin type III repeats, seemed to be more pronounced in 5.2 and 2.9 kb NCAM mRNAs than in the 7.4 and 6.7 kb mRNAs. During postnatal development an increase in the fraction of 6.7 kb NCAM mRNA containing the exons a and AAG was observed. However, during aging the fraction of NCAM mRNAs containing this exon combination seemed constant. At the protein level, NCAM‐A was downregulated both during development and aging. No changes were observed during aging in the composition of soluble NCAM forms in the brain, cerebrospinal fluid or blood plasma. The amount of NCAM in rat brain decreased during postnatal development, but remained at a constant level from postnatal day 40 to old age.To conclude, several changes in NCAM expression occur during early postnatal development emphasizing the important role of this molecule in the morphogenetic processes. During aging, a significant selective downregulation of NCAM‐A was observed indicating that in general only minor regenerative processes occur in the brain.
Concurrent isolation and characterization of oligodendrocytes, microglia and astrocytes from adult human spinal cord
Authors: Whittemore Scott R. , Sanon Henry R. , Wood Patrick M. 
Published: April 2003

AbstractA cellular preparation of highly enriched oligodendrocytes was obtained from adult human spinal cord by Percoll gradient centrifugation followed by either differential adhesion or fluorescence‐activated cell sorting after immunostaining with an antibody against galactocerebroside (Ol). The adherent and O1‐negative cell fractions were ⪢96% microglia. The non‐adherent and O1‐positive fractions were ⪢96% positive for the oligodendrocyte markers O4 and O1, 0–2% positive for glial fibrillary acidic protein, and were devoid of neuronal or microglial markers. If the oligodendrocyte fraction was co‐cultured with purified dissociated rat dorsal root ganglion neurons, the oligodendrocytes adhered to the axons and their numbers increased over a 4 week period. However, myelin sheaths were not produced around axons in these cultures. In contrast, if the oligodendrocyte cell fraction was grown alone in culture for ⪢3 weeks, the number of oligodendrocytes decreased and a layer of astrocytes developed underneath the oligodendrocytes. The oligodendrocytes could be eliminated from these cultures by subsequent passaging, thus producing cultures of pure astrocytes. The astrocytes accumulated both K+ and glutamate with kinetic properties similar to those reported for rodent astrocytes. We suggest that these astrocytes arose in part from an O4/O1‐positive precursor which did not initially express glial fibrillary acidic protein. These results define a relatively simple method by which highly enriched populations of oligodendrocytes, astrocytes and microglia can be obtained from adult human spinal cord.
Interleukin‐1β does not induce reactive astrogliosis, neovascularization or scar formation in the immature rat brain
Authors: Sievers Jobst , Struckhoff Gernot , Puchner Maximilian 
Published: April 2003

AbstractThe adult mammalian central nervous system (CNS) reacts to a penetrating injury with the formation of a glial scar consisting of a newly formed glia limitans accessoria, basement membrane and meningeal fibroblasts. By contrast, in fetal and perinatal mammals a similar injury evokes only a reduced reactive astrogliosis, and a typical astroglial scar begins to develop only when the lesion has been placed beyond a critical developmental period. In the present investigation we have tested the hypothesis that IL‐1β plays a pivotal role in the process of cicatrization, by investigating whether immature animals develop a glial scar after IL‐1β is injected into their CNS. Adult female rats were given injections of 2U recombinant IL‐1β or PBS alone in the contralateral cortex in identical positions of the cerebral hemispheres. Postnatal day 2 (P2) rats received injections of either 1U IL‐β or PBS into the lateral aspect of the frontal cortex on each side. The animals were sacrificed 4 and 14 days post injection and the perilesional area was assessed for astrogliosis (expression of GFAP‐immunoreactivity and the activity of glutamine synthetase), neovascularization (laminin‐immunoreactivity on blood vessels at the lesion site), and the formation of a gliomeningeal scar (GFAP‐ and laminin‐immunoreactivity at the lesion site). Using similar criteria for the evaluation, we found that in adult animals some of the processes associated with cicatrization are augmented. In the immature animals, however, the formation of the glio‐meningeal scar is not altered by IL‐1β, i.e. it remains absent. We conclude that IL‐1β augments some responses of the cells involved in wound healing in the adult CNS, but does not alter key mechanisms operative in the reaction of the brain to a penetrating injury, as shown by its inability to alter the stage specific response of the immature brain.
A comparison of the ‘American System of Manufactures’ circa 1850 with Just in Time methods
Authors: Wilson James M. 
Published: April 2003

AbstractThe introduction of Just In Time methods in American business often raises issues of cultural change. These questions may be eased by recognizing that JIT shares many characteristics with methods used in the US during the 1800s. A comparative analysis of the American System of Manufactures ca. 1850 with Just in Time systems shows significant similarities in their development and characteristics. Parallels to their reliance on specialised plant and equipment are described, together with the emphasis on the manufacturing importance of quality, recognition of the impact of resource endowments, cultural and behavioural characteristics, use of appropriate facility layout, and general organizational and structural arrangements. Differences arising from reward systems, labour mobility and a number of technical aspects such as power generation and distribution systems are also analysed. The American System of Manufactures provided companies using JIT with a sophisticated managerial and technical capability. Companies that developed and used the American System of Manufactures in the mid‐1800s share many of the characteristics of successful companies today.
Measurement of lesion area and volume by three‐dimensional spoiled gradient‐echo MR imaging in osteonecrosis of the femoral head
Authors: Kishida Yuki , Nishii Takashi , Sugano Nobuhiko , Nakanishi Katsuyuki , Sakai Takashi , Miki Hidenobu , Ochi Takahiro , Yoshikawa Hideki 
Published: April 2003

AbstractThe purpose of this investigation is to evaluate the diagnostic ability of three‐dimensional spoiled gradient‐echo (3D SPGR) magnetic resonance (MR) imaging in cases of osteonecrosis of the femoral head (ONFH), and to determine the accuracy of 3D SPGR imaging in area and volume measurement of ONFH. T1‐weighted spin‐echo (SE) and 3D SPGR imaging were performed on 20 femoral heads obtained from patients with ONFH. After MR imaging, the femoral heads were cut parallel to the imaging plane and were evaluated histologically. Areas and volumes of necrotic lesions were measured with a computer program and the deviation between MR images and anatomical measurements was evaluated. A low signal intensity band on 3D SPGR MR images was observed in all femoral heads and corresponded histologically to repaired marrow with viable fibrous mesenchymal tissue. The area proximate to the low band area coincided with the necrotic region. Both area and volume measurements by T1‐weighted SE and 3D SPGR images showed a strong correlation to histological measurements. The discrepancies between histological and imaging results were minimal in 3D SPGR imaging, especially at the anterior and posterior portions of the femoral head. Three‐dimensional SPGR imaging provides more accurate measurements of the area and volume of a necrotic lesion than T1‐weighted SE imaging. © 2003 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Cell proliferation in response to GABA in postnatal hippocampal slice culture
Authors: Ben‐Yaakov G. , Golan H. 
Published: April 2003

AbstractRecent studies have implicated the inhibitory neurotransmitter GABA in the regulation of cell migration and proliferation in the embryonic brain. Herein, we examine the possibility that these effects are maintained postnatally. Using 5 days postnatal hippocampus, we tested GABA effects on growth into an incision made in CA1 and the possibility that this response to GABA is mediated via GABAA‐receptor. Our data shows that GABA promotes neurite growth, cell proliferation and migration up to day 6 in vitro. GABAA‐receptor is not involved in the trophic response to either exogenous or endogenous GABA. Moreover, GABA induced a 20% increase in NGF secretion to the growth medium, in a similar time frame to its effect on growth. Elevated NGF secretion was suppressed by the inhibition of cell proliferation. These results suggest that GABA can promote growth in postnatal hippocampal tissue. The effect involves cell proliferation and NGF secretion and does not depend on GABAA‐receptor activation.
Beta‐blocker benefit according to severity of heart failure
Authors: Bouzamondo Anissa , Hulot Jean‐Sébastien , Sanchez Paola , Lechat Philippe 
Published: April 2003

AbstractBackground and aims:Beta‐blockers are an established treatment for chronic heart failure. However, the relationship between their benefit and the severity of the disease remains to be determined.Methods and results:We studied the relationship between amplitude of benefit of beta‐blockers and severity of chronic heart failure, based on data for mortality and hospitalizations for worsening heart failure, using a meta‐analysis of randomized controlled trials, complementary subgroup analyses and analysis of individual data from the CIBIS II trial. In the meta‐analysis, mortality was reduced by 22% (95%CI: 16 to 28) and hospitalizations for worsening heart failure by 24% (95%CI: 20 to 29). Benefit was similar with metoprolol, bisoprolol and carvedilol. After exclusion of bucindolol trials, due to the heterogeneity of results for mortality, the reduction in mortality was similar according to the severity of heart failure, assessed either by left ventricular ejection fraction or by New York Heart Association classification. In CIBIS II, beta‐blockers induced a significant reduction in mortality of 45% (95%CI: 9 to 66), 41% (95%CI: 17 to 59) and 23% (95%CI: 1 to 40) in the low, intermediate and high risk groups, respectively. Hospitalizations were reduced by 35% (95%CI: 2 to 57), 41% (95%CI: 18 to 58) and 23% (95%CI: 0 to 41), there was no significant difference between the three score groups.Conclusion:We conclude that the amplitude of benefit of the beta‐blockers carvedilol, metoprolol and bisoprolol on mortality and morbidity is similar, regardless of the severity of chronic heart failure.
Reliable prediction of T‐cell epitopes using neural networks with novel sequence representations
Authors: Nielsen Morten , Lundegaard Claus , Worning Peder , Lauemøller Sanne Lise , Lamberth Kasper , Buus Søren , Brunak Søren , Lund Ole 
Published: April 2003

AbstractIn this paper we describe an improved neural network method to predict T‐cell class I epitopes. A novel input representation has been developed consisting of a combination of sparse encoding, Blosum encoding, and input derived from hidden Markov models. We demonstrate that the combination of several neural networks derived using different sequence‐encoding schemes has a performance superior to neural networks derived using a single sequence‐encoding scheme. The new method is shown to have a performance that is substantially higher than that of other methods. By use of mutual information calculations we show that peptides that bind to the HLA A*0204 complex display signal of higher order sequence correlations. Neural networks are ideally suited to integrate such higher order correlations when predicting the binding affinity. It is this feature combined with the use of several neural networks derived from different and novel sequence‐encoding schemes and the ability of the neural network to be trained on data consisting of continuous binding affinities that gives the new method an improved performance. The difference in predictive performance between the neural network methods and that of the matrix‐driven methods is found to be most significant for peptides that bind strongly to the HLA molecule, confirming that the signal of higher order sequence correlation is most strongly present in high‐binding peptides. Finally, we use the method to predict T‐cell epitopes for the genome of hepatitis C virus and discuss possible applications of the prediction method to guide the process of rational vaccine design.
Detection of Macrolide Resistance in <i>Streptococcus pneumoniae</i>
Authors: Kimura Taku , Horii Toshinobu , Morita Motoki , Muramatsu Hideaki , Kanno Takashi , Maekawa Masato 
Published: April 2003

We determined the susceptibilities of recent clinical isolates of <i>Streptococcus pneumoniae</i> to 19 antibiotics. The frequency of erythromycin nonsusceptibility was high, i.e. 8/13 (61.5%), 10/14 (71.4%) and 11/11 isolates (100%) from 13 penicillin-susceptible, 14 penicillin-intermediate and 11 penicillin-resistant <i>S. pneumoniae</i>, respectively. Macrolide resistance was detected by polymerase chain reaction (PCR) and disk diffusion methods. Of these erythromycin-nonsusceptible pneumococcal isolates, 13/29 (44.8%) isolates contained genomic copies of <i>mefA</i> and showed non-‘D’-shaped zones of inhibition observed around rokitamycin and/or clindamycin disks. Sixteen out of 29 isolates (55.2%) contained copies of <i>ermB</i> and showed typical ‘D’-shaped zones of inhibition, except one isolate. Although the macrolide resistance determinants, <i>mefA</i> and <i>ermB</i>, could be identified by PCR and disk diffusion methods, PCR methods were more reliable in elucidating these determinants. The susceptibility pattern to 14-, 15- and 16-membered macrolides and clindamycin differed between the <i>mefA</i>+ and <i>ermB</i>+ isolates. All isolates were susceptible to levofloxacin, sparfloxacin and vancomycin. The MICs of sitafloxacin were lowest among the fluoroquinolones examined for 38 isolates.
A Parametric Manipulation of Factors Affecting Task-induced Deactivation in Functional Neuroimaging
Authors: McKiernan Kristen A. , Kaufman Jacqueline N. , Kucera-Thompson Jane , Binder Jeffrey R. 
Published: April 2003

Abstract
Task-induced deactivation (TID) refers to a regional decrease in blood flow during an active task relative to a “resting” or “passive” baseline. We tested the hypothesis that TID results from a reallocation of processing resources by parametrically manipulating task difficulty within three factors: target discriminability, stimulus presentation rate, and short-term memory load. Subjects performed an auditory target detection task during functional magnetic resonance imaging (fMRI), responding to a single target tone or, in the short-term memory load conditions, to target sequences. Seven task conditions (a common version and two additional levels for each of the three factors) were each alternated with “rest” in a block design. Analysis of covariance identified brain regions in which TID occurred. Analyses of variance identified seven regions (left anterior cingulate/superior frontal gyrus, left middle frontal gyrus, right anterior cingulate gyrus, left and right posterior cingulate gyrus, left posterior parieto-occipital cortex, and right precuneus) in which TID magnitude varied across task levels within a factor. Follow-up tests indicated that for each of the three factors, TID magnitude increased with task difficulty. These results suggest that TID represents reallocation of processing resources from areas in which TID occurs to areas involved in task performance. Short-term memory load and stimulus rate also predict suppression of spontaneous thought, and many of the brain areas showing TID have been linked with semantic processing, supporting claims that TID may be due in part to suspension of spontaneous semantic processes that occur during “rest” (Binder et al., 1999). The concept that the typical “resting state” is actually a condition characterized by rich cognitive activity has important implications for the design and analysis of neuroimaging studies.
When Seeing Is Not Believing: Children's Understanding of Humans' and Non-Humans' Use of Background Knowledge in Interpreting Visual Displays
Authors: Barrett Justin , Newman Roxanne Moore , Richert Rebekah 
Published: April 2003

Abstract
To explore 3- to 7-year-old children's developing understanding of human and non-human minds, a battery of "background knowledge" tasks was administered to 51 American children. The children were asked to speculate about how three other intentional agents (mother, dog, and God) would understand various visual displays. First, children answered when they themselves did not understand the displays, then they answered after they had been given information necessary to understand the displays. Results revealed that children begin to understand the role of background knowledge around the same age that they pass false-belief tasks; and that before thoroughly understanding the role of background knowledge they already begin to discriminate between different types of minds. By age four, children began to show some understanding that because of having different minds than people, God is more able and dogs are less able to understand some visual displays even with full visual access.
Numerical diagnosis of a small, quasi‐tropical cyclone over the western Mediterranean: Dynamical vs. boundary factors
Authors: Homar V. , Romero R. , Stensrud D. J. , Ramis C. , Alonso S. 
Published: April 2003

AbstractA small, quasi‐tropical cyclone occurred on 12 September 1996 over the western Mediterranean. Intense convective activity over the region during this period also produced a tornado outbreak in the Balearic Islands and torrential precipitation over eastern mainland Spain.Mesoscale model runs properly simulate the cyclone formation and show convection and heavy precipitation following the cyclone trajectory during its eastward progression. A sensitivity study examining the upper‐level dynamic forcing, latent‐ and sensible‐heat fluxes from the sea, and orography is conducted. A potential‐vorticity (PV) inversion technique is used to reduce the amplitude of the upper‐level trough in the model initial conditions. The results show that neither the orography nor the sensible‐heat flux from the sea play a significant role during this particular cyclone development. Conversely, both the latent‐heat flux and the upper‐level trough are shown to be crucial for low‐level cyclogenesis. Features common to hurricane‐like polar lows are found for the cyclone, and an analysis of the precise role of the upper‐level structures and the convective development is conducted.A factor‐separation technique is used to determine the individual effects of the aforementioned factors, as well as their interaction. At the first stage of the cyclogenesis, the upper‐level PV anomaly enhanced the low‐level circulation of the synoptic‐scale low and enhanced the latent‐heat flux from the sea. During its mature stage, the circulation associated with the small‐scale cyclone enhanced the latent‐heat flux from the sea, thereby helping to maintain the development of deep convection, and inducing further cyclone deepening by diabatic heating. This scenario has many similarities with the air–sea interaction instability mechanism. Thus, the joint action of the upper‐level anomaly, as a spin‐up agent, and the latent‐heat flux, as a sustainer of convection, emerges as the primary factor for the genesis and evolution of the small quasi‐tropical cyclone. Copyright © 2003 Royal Meteorological Society
Solid‐state polymerization of poly(ethylene terephthalate). I. Experimental study of the reaction kinetics and properties
Authors: Kim T. Y. , Lofgren E. A. , Jabarin S. A. 
Published: April 2003

AbstractThe solid‐state polymerization (SSP) reaction kinetics of poly(ethylene terephthalate) were investigated in connection with the initial precursor intrinsic viscosity (IV; molecular weight). Evaluations were performed with otherwise equivalent precursors melt‐polymerized to IVs of 0.50, 0.56, and 0.64 dL/g. The changes in the molecular weight and other properties were monitored as functions of the reaction times at solid‐state temperatures of 160–230°C. Precursors with higher initial molecular weights exhibited higher rates of SSP than those with lower initial values, as discussed in connection with the levels of crystallinity and the carboxyl and hydroxyl end‐group composition. Activation energies decreased at temperatures above 200°C, and this indicated a change in the SSP reaction mechanism. At temperatures of 200–230°C, similar activation energies were required for the polymerization of all three precursors. Lower temperature polymerizations, from 160 to 200°C, required higher activation energies for all precursors, with the 0.50‐IV material requirement almost twice as high as that calculated for the higher IV precursors. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 197–212, 2003