bluuebunny/crossref_metadata_2025_split huggingface dataset:
Streptomycetes cultured on glass beads: Sample preparation for SEM
Authors: Kofroňová Olga , Nguyen Liem Duy , Weiser Jaroslav , Benada Oldřich 
Published: October 2002

AbstractWe demonstrate the preparation of samples of streptomycetes (Streptomyces coelicolor, S. aureofaciens) cultured on glass beads (balotina) for scanning electron microscopy. The main trick of the method consists in immobilization of glass beads with low‐melting agarose. The samples are then fixed in OsO4 vapors followed by dehydration in vapors of absolute ethanol. No air‐to‐liquid transition during the sample preparation occurs. Consequently, whole cell cycle of streptomycetes in the term of mycelial morphology can readily be studied by this method. Microsc. Res. Tech. 58:111–113, 2002. © 2002 Wiley‐Liss, Inc.
Differential regulation of spontaneous and heat‐induced HSP 70 expression in developing zebrafish (Danio rerio)
Authors: Yeh Fu‐lung , Hsu Todd 
Published: October 2002

AbstractA spontaneous high expression of heat shock protein 70 (HSP 70) was found to arise in zebrafish (Danio rerio) at the larval stage (84 hr after fertilization). The level of HSP 70 in 84‐hr‐old larvae was estimated to be six‐ to eightfold that of 12‐hr‐old embryos. As heat‐induced HSP 70 synthesis in many eukaryotic organisms is known to be mediated by a transcriptional‐dependent pathway activated by heat shock factor 1 (HSF‐1), we then examined if the spontaneous and heat‐induced HSP 70 synthesis in zebrafish were controlled by the same mechanism. Although the transient increase of a 62‐kDa HSF‐1‐like polypeptide in 72‐ to 96‐hr‐old larvae seemed to correlate with the onset of the spontaneous HSP 70 production, an anti‐HSF‐1 antibody cocktail supershifted the heat shock element (HSE) binding complex induced by stressed but not by unstressed zebrafish extracts. Northern blot and quantitative RT‐PCR analysis demonstrated the predominant presence of the cognate form of hsp 70 mRNA (hsc 70 mRNA) in developing zebrafish. The extent of heat‐induced HSP 70 production in 84‐hr‐old larvae matched well with a dramatic increase in hsp 70 mRNA accumulation, while no apparent increase in total hsp 70 mRNA could be detected in 72‐ to 84‐hr‐old unstressed larvae by northern blot analysis. The stable expression of hsc 70 mRNA specific to β‐actin mRNA in normal zebrafish was confirmed by RT‐PCR analysis. Hence, the spontaneous high expression of HSP 70 in zebrafish is believed to be controlled by a mechanism different from the HSF‐1‐dependent transcriptional activation of hsp 70 under heat stress. J. Exp. Zool. 293:349–359, 2002. © 2002 Wiley‐Liss, Inc.
Chloride‐ATPase dephosphorylation in Aplysia gut
Authors: GERENCSER GEORGE A. , ZHANG JIANLIANG 
Published: October 2002

AbstractThe present study was done primarily to compare cation‐ATPase dephosphorylation kinetics with a Cl−‐ATPase's dephosphorylation kinetics because of the paucity of information in this area. Utilizing a proteoliposomal preparation containing Cl−‐ATPase from Aplysia gut, it was demonstrated that dephosphorylation of this P‐type ATPase was absolutely dependent upon Cl−. Adenosine triphosphate (ATP) concentrations directly stimulated dephosphorylation of Cl−‐ATPase in the presence of increasing concentrations of Cl−. It was also shown that the calculated rate constant for E1‐P disintegration was 20/sec. This rate constant value approximated E1‐P rate constant disintegration values for other electrogenic, uniport P‐type ATPases. Therefore, it was concluded from these results that the Cl−‐ATPase dephosphorylation kinetics did not differ greatly from cation‐ATPase dephosphorylation kinetics. © 2002 Wiley‐Liss, Inc.
An experimental test of the relationship between temporal variability of feeding opportunities and baseline levels of corticosterone in a shorebird
Authors: RENEERKENS JEROEN , PIERSMA THEUNIS , RAMENOFSKY MARILYN 
Published: October 2002

AbstractIn this study, we tested the hypothesis that baseline corticosterone levels increase with a change from constant to variable feeding schedules. Captive red knots, Calidris canutus, were presented with food that was either available during the same time each day (constant) or starting at variable times during the day. Food intake rates, frequency of aggressive interactions, and baseline levels of corticosterone were measured. In the majority of cases, red knots showed higher plasma corticosterone concentrations during feeding schedules that were irregular than when food was available at consistent times. These findings are supported by a previous study that showed that red knots take a long time to adjust to the newly offered, predictable conditions of their aviary environment. The frequency of conflicts in the different groups and (size‐corrected) body mass were not correlated with average corticosterone level. The results are examined in the light of literature showing that increases in corticosterone in response to acute, unpredictable events mediate behavioral responses such as increased explorative behavior and memory. For red knots that have to find their food on the temperate‐zone mudflats in Western Europe, an increased circulating corticosterone level may be adaptive during periods when the patchily distribution of buried bivalves and the burying behavior of such prey presents them with a variable and unpredictable food supply. © 2002 Wiley‐Liss, Inc.
Myocyte ploidy in heart chambers of birds with different locomotor activity
Authors: Anatskaya Olga V. , Vinogradov Alexander E. 
Published: October 2002

AbstractThe ploidy levels of atrio‐ and ventriculocytes were determined by means of cytofluorimetry in 31 species of birds. The obtained data were collated with postnatal growth rate, heart mass index, and relative masses of heart chambers. The difference between mean ploidy of cardiomyocytes in the left and right atrium is small (7.9±0.6%) and comparable to the difference in the masses of these chambers (10.5±0.8%). The difference between mean ploidy of atrio‐ and ventriculocytes is most pronounced for the left and right parts of heart (23.9±1.4% and 24.0±1.3%, respectively) and corresponds to considerable differences in the average masses of atria and ventricles (4.5‐fold and 2.1‐fold, respectively). The mean cardiomyocyte ploidy levels in the left and right ventricles differ only slightly, as in the case of atria (by 8.1±0.5%), whereas the average mass of the left ventricle is greater by 237±16%. This discord can be explained by peculiarities of the growth, which is nonproportionally faster in the left ventricle during the last stage of proliferative heart growth as compared to other chambers. The cardiomyocyte ploidy is higher in birds with a relatively small heart and lower ability to flight. Birds with a high locomotor activity in the adult state have an athletic heart (mass index >1%); they are fast growing, altricial species with a low heart workload in the early postnatal ontogenesis. Birds with a low locomotor activity at the adult state are precocial; they grow slowly and have a high locomotor activity from the first minutes of life. Thus, notwithstanding the fact that a greater elevation of cardiomyocyte ploidy level is acquired under a higher functional load (ventricles vs. atria, left vs. right part of the heart), it is associated with a lower functional potential of the organ at the adult state. The level of somatic polyploidy can be considered an indicator of developmental tensions arising due to a high workload during the growth of a given organ and deficiency of resources invested into this growth. J. Exp. Zool. 293:427–441, 2002. © 2002 Wiley‐Liss, Inc.
Gallium nitrate: effects on cartilage during limb regeneration in the axolotl, Ambystoma mexicanum
Authors: Tassava Roy A. , Mendenhall Luciara , Apseloff Glen , Gerber Nicholas 
Published: October 2002

AbstractGallium nitrate, a drug shown to have efficacy in Paget's disease of bone, hypercalcemia of malignancy, and a variety of experimental autoimmune diseases, also inhibits the growth of some types of cancer. We examined dose and timing of administration of gallium nitrate on limb regeneration in the Mexican axolotl, Ambystoma mexicanum. Administered by intraperitoneal injection, gallium nitrate inhibited limb regeneration in a dose‐dependent manner. Gallium nitrate initially suppressed epithelial wound healing and subsequently distorted both anterior‐posterior and proximo‐distal chondrogenic patterns. Gallium nitrate given at three days after amputation severely inhibited regeneration at high doses (6.25 mg/axolotl) and altered the normal patterning of the regenerates at low doses (3.75 mg/axolotl). Administration of 6.25 mg of gallium nitrate at four or 14 days prior to amputation also inhibited regeneration. In amputated limbs of gallium‐treated axolotls, the chondrocytes were lost from inside the radius/ulna. Limbs that regenerated after gallium treatment was terminated showed blastema formation preferentially over the ulna. New cartilage of the regenerate often attached to the sides of the existing radius/ulna proximally into the stump and less so to the distal cut ends. J. Exp. Zool. 293:384–394, 2002. © 2002 Wiley‐Liss, Inc.
Distribution of GFAP immunoreactive structures in the rhombencephalon of the sterlet (Acipenser ruthenus) and its evolutionary implication
Authors: Kálmán Mihály , Ari Csilla 
Published: October 2002

AbstractPrevious studies have revealed that although the brains of cypriniform teleosts (iberian barb, Barbus comiza; carp, Cyprinus carpio; goldfish, Carassius auratus) are rich in glial fibrillary acidic protein (GFAP), they have, however, areas devoid of GFAP immunoreactivity. The largest ones of these are in the rhombencephalon, e.g., the zones of the sensory and motor neurons in the vagal lobe. Our studies in amniotes suggested that the GFAP immunonegative areas could be characteristic of the more advanced brains (avian and mammalian), whereas no similar areas were found in reptiles. A similar tendency was found in the Chondrichthyes, i.e., GFAP immunonegative areas appeared as brain complexity progressed. The question arose whether the GFAP immunonegative brain areas in the Teleostei were also the result of such a tendency. Within the radiation of ray‐finned fishes (Actinopterygii), Chondrostei represent a less advanced level as compared to the Teleostei. Therefore, the distribution of GFAP immunoreactivity was investigated in the rhombencephalon of the sterlet (Acipenser ruthenus) as a representative of Chondrostei, and in the carp. Serial vibratome sections were processed according to the avidin‐biotinylated horseradish peroxidase method.Several comparable GFAP immunoreactive structures were found in the two species: the dense periventricular ependymoglial plexus, the midsagittal glial septum, the small glial septa separating the nerve fiber bundles, and the wide glial endfeet lining the meningeal surface. In the vagal lobe in the zones adjacent to the meningeal and ventricular surfaces, the glial structures also proved to be similar. In contrast to the carp, however, no areas were found devoid of GFAP immunoreactivity in the sterlet.The results suggest that this trend of glial evolution, i.e., GFAP immunonegative areas appearing as brain complexity progressed, is a common feature shared by Actinopterygii, Amniota, and Chondrichthyes, despite their separate evolutionary histories. J. Exp. Zool. 293:395–406, 2002. © 2002 Wiley‐Liss, Inc.
Amphi‐Eomes/Tbr1: an amphioxus cognate of vertebrate Eomesodermin and T‐Brain1 genes whose expression reveals evolutionarily distinct domain in amphioxus development
Authors: Satoh Gouki , Takeuchi Jun K. , Yasui Kinya , Tagawa Kunifumi , Saiga Hidetoshi , Zhang Peijun , Satoh Nori 
Published: October 2002

AbstractA cDNA for a novel T‐box containing gene was isolated from the amphioxus Branchiostoma belcheri. A molecular phylogenetic tree constructed from the deduced amino acid sequence of the isolated cDNA indicates that this gene belongs to the T‐Brain subfamily. In situ hybridization reveals that the expression is first detected in the invaginating archenteron at the early gastrula stage and this expression is down‐regulated at the neurula stage. In early larvae, the expression appears again and transcripts are detected exclusively in the pre‐oral pit (wheel organ‐Hatschek's pit of the adult). In contrast to the vertebrate counterparts, no transcripts are detected in the brain vesicle or nerve cord throughout the development. These results are interpreted to mean that a role of T‐Brain products in vertebrate forebrain development was acquired after the amphioxus was split from the lineage leading to the vertebrates. On the other hand, comparison of the tissue‐specific expression domain of T‐Brain genes and other genes between amphioxus and vertebrates revealed that the pre‐oral pit of amphioxus has several molecular features which are comparable to those of the vertebrate olfactory and hypophyseal placode. J. Exp. Zool. (Mol. Dev. Evol.) 294:136–145, 2002. © 2002 Wiley‐Liss, Inc.
Evolution of developmental functions by the Eomesodermin, T‐brain‐1, Tbx21 subfamily of T‐box genes: insights from amphioxus
Authors: Horton Amy C. , Gibson‐Brown Jeremy J. 
Published: October 2002

AbstractWe have identified an amphioxus T‐box gene that is orthologous to the Eomesodermin, T‐brain‐1, and Tbx21 genes of vertebrates, and we have characterized its expression pattern during embryonic and larval development. AmphiEomes/Tbr1/Tbx21 is maternally expressed in oocytes and cleavage stage embryos. After the onset of zygotic transcription at the blastula stage, it is expressed in invaginating mesendoderm cells during gastrulation, but it is downregulated in presumptive ectoderm and neurectoderm. Expression is seen in both axial and paraxial mesendoderm in neurulae and early larvae, but it is not detected in differentiated endoderm, somites, or notochord. Expression persists in mesendoderm cells of the tail bud in early larvae, but it disappears between 1 to 1.5 days post fertilization. Unlike orthologous genes in basal deuterostomes or vertebrates, no anterior neural expression domain is detected at any stage of development. Integrating phylogenetic and developmental data, we have reconstructed the evolutionary history of the Eomesodermin/Tbr1/Tbx21 subfamily of T‐box genes from a single ancestral locus that originated very early in metazoan evolution, before the evolution of triploblasts from their diploblast ancestor. J. Exp. Zool. (Mol. Dev. Evol.) 294:112–121, 2002. © 2002 Wiley‐Liss, Inc.
Activation of silenced transgene expression in neural precursor cell lines by inhibitors of histone deacetylation
Authors: Rosenqvist Nina , Hård af Segerstad Caroline , Samuelsson Christofer , Johansen Jens , Lundberg Cecilia 
Published: October 2002

AbstractBackgroundEx vivo gene therapy in the central nervous system (CNS) holds great promise for diseases such as the neurodegenerative disorders. However, achieving stable, long‐term transgene expression in grafted cells has proven problematic. This study reports the establishment of an in vitro model of transgene down‐regulation in cells grafted to the CNS using the immortalized neural progenitor cell lines HiB5 and RN33B.MethodsNeural cell lines were transduced at 33°C with different GFP constructs, both viral and non‐viral, containing either viral or non‐viral promoters. Cell differentiation in vitro was obtained by culturing the cells at 37°C in serum‐free defined media, which halts cell division, and GFP‐expression was analysed by FACS. As early as day 3 of culture at 37°C, the transgene expression decreased markedly in most cell lines. To validate the assay, the same clones were grafted to the adult rat striatum and the down‐regulation of GFP‐expression was evaluated.ResultsThe temporal pattern of down‐regulation was found to be similar in vitro and in vivo. Using this assay, it was shown that addition of inhibitors of histone deacetylation, but not an inhibitor of DNA methylation, reversed the silencing of GFP in quiescent neural progenitors by up to 308% of control values.ConclusionThese results suggest that the same mechanisms controlling gene transcription of the host cell's genome are active in controlling transgene expression and that this should be taken into account when constructing vectors for gene therapy. The assay reported in this study could be used as a screening method to evaluate new vectors. Copyright © 2002 John Wiley & Sons, Ltd.
Somatic gene transfer into the lactating ovine mammary gland
Authors: Düchler Markus , Pengg Margret , Schüller Susanne , Pfneisl Franz , Bugingo Christoph , Brem Gottfried , Wagner Ernst , Schellander Karl , Müller Mathias 
Published: October 2002

AbstractBackgroundSomatic gene therapy requires safe and efficient techniques for the gene transfer procedure. The ovine mammary gland is described as a model system for the evaluation of somatic gene transfer methods.MethodsDifferent gene delivery formulations were retrogradely injected into the mammary gland of lactating sheep. The efficiency of the gene transfer was subsequently measured by the detection of the secreted transgene products in the milk. To counteract the milk flow in the lactating gland caused by the permanent milk production, a newly developed pretreatment of the mammary gland with hyperosmotic solutions was applied. In addition, in vivo electroporation of DNA into the mammary gland is described.ResultsGene transfer using naked DNA or simple complexes of DNA with polycations did not result in traceable amounts of reporter gene products. However, utilizing the complex cationic lipid DOSPER, a peak expression of about 400 ng/ml was observed 6 days after transfection. Maximum expression rates of more than 1 µg/ml were obtained by combining hyperosmotic pretreatment and receptor‐mediated gene transfer. For the in vivo electroporation, the proof of principle for this technique in the mammary gland is reported.ConclusionsThe ovine mammary gland turned out to be a very well suited as a model system for evaluation and optimization of various gene transfer protocols. Copyright © 2002 John Wiley & Sons, Ltd.
Intracellular processing and stability of DNA complexed with histidylated polylysine conjugates
Authors: Gonçalves Christine , Pichon Chantal , Guérin Brigitte , Midoux Patrick 
Published: October 2002

AbstractBackgroundGlycosylated polylysines and histidylated polylysines complexed with plasmid DNA (pDNA) were proposed to develop polymer‐based gene delivery systems. The present work has been undertaken in two steps to study the uptake and the intracellular processing of pDNA, which are still poorly understood in the polyfection pathway.Methods and resultsThe kinetics of the uptake and the intracellular processing of pDNA complexed with lactosylated polylysine, histidylated polylysine or histidylated polylysine bearing lactosyl residues (polyplexes) into a CF human airway epithelial cell line were assessed by flow cytometry and confocal microscopy. Complexes formed from histidylated polylysine, even though they were less taken up by cells, show better transfection efficiency with compared with lactosylated complexes. Lactosylated polymers segregated more rapidly when compared with non‐lactosylated polymers into compartments different from those containing pDNA on internalization. Intracellular location and pH measurements indicated that polymers ended up in compartments of pH ∼6.2 while pDNA reached less acidic compartments of pH ∼6.6. These compartments did not contain the LAMP‐1 lysosomal marker.ConclusionsThe present study exhibits that, upon internalization, pDNA and polylysine conjugates underwent segregation with a rate depending on the polylysine substitution and polymer degradation. The better transfection efficiency of polyplexes with histidylated polylysine can be ascribed to their prolonged stability inside the endocytic vesicles that likely favored the pDNA escape in the cytosol. Copyright © 2002 John Wiley & Sons, Ltd.
Interactive body magnetic resonance fluoroscopy using modified single‐shot half‐Fourier rapid acquisition with relaxation enhancement (RARE) with multiparameter control
Authors: Makki Malek , Graves M.J. , Lomas D.J. 
Published: October 2002

AbstractPurposeTo develop a technique for interactive fluoroscopic abdominal magnetic resonance imaging (MRI) based on a single‐shot half‐Fourier rapid acquisition and relaxation‐enhanced sequence.Materials and MethodsThe sequence was modified by incorporating inner‐volume excitation, driven‐equilibrium signal enhancement, and reduced flip angle refocusing pulses. Contrast control was provided by integrating “on‐the‐fly” selection of phase encoding view order, fat suppression, and section thickness. The resulting sequence was evaluated with phantom experiments to quantify the signal‐to‐noise ratio (SNR) effects of the modifications and in healthy volunteers for imaging the bile ducts, stomach, and duodenum using water and gaseous contrast media.ResultsObserved SNR relating to driven‐equilibrium and flip angle scaling matched theoretical predictions. Volunteer examinations demonstrated the ability of the modified sequence to provide interactive, artifact‐free imaging of the abdomen, including switching between conventional proton density‐weighted, T2‐weighted imaging and “hydrographic” projection imaging.ConclusionRefinement of this technique may provide an abdomino‐pelvic imaging capability similar in concept to real‐time ultrasound, but with the advantages of MRI. J. Magn. Reson. Imaging 2002;16:85–93. © 2002 Wiley‐Liss, Inc.
Applications of neural network analyses to in vivo 1H magnetic resonance spectroscopy of Parkinson disease patients
Authors: Axelson David , Bakken Inger Johanne , Susann Gribbestad Ingrid , Ehrnholm Benny , Nilsen Gunnar , Aasly Jan 
Published: October 2002

AbstractPurposeTo apply neural network analyses to in vivo magnetic resonance spectra of controls and Parkinson disease (PD) patients for the purpose of classification.Materials and MethodsNinety‐seven in vivo proton magnetic resonance spectra of the basal ganglia were recorded from 31 patients with (PD) and 14 age‐matched healthy volunteers on a 1.5‐T imager. The PD patients were grouped as follows: probable PD (N = 15), possible PD (N = 11), and atypical PD (N = 5). Total acquisition times of approximately five minutes were achieved with a TE (echo time) of 135 msec, a TR (repetition time) of 2000 msec, and 128 scan averages. Neural network (back propagation, Kohonen, probabilistic, and radial basis function) and related (generative topographic mapping) data analyses were performed.ResultsConventional data analysis showed no statistically significant differences in metabolite ratios based on measuring signal intensities. The trained networks could distinguish control from PD with considerable accuracy (true positive fraction 0.971, true negative fraction 0.933). When four classes were defined, approximately 88% of the predictions were correct. The multivariate analysis indicated metabolic changes in the basal ganglia in PD.ConclusionA variety of neural network and related approaches can be successfully applied to both qualitative visualization and classification of in vivo spectra of PD patients. J. Magn. Reson. Imaging 2002;16:13–20. © 2002 Wiley ‐Liss, Inc.