bluuebunny/crossref_metadata_2025_split huggingface dataset:
A MECHANISTIC VIEW OF THE NON‐IDEAL OSMOTIC AND MOTIONAL BEHAVIOR OF INTRACELLULAR WATER
Authors: CAMERON I.L , KANAL K.M , KEENER C.R , FULLERTON G.D 
Published: September 2002

AbstractIt is commonly assumed that essentially all of the water in cells has the same ideal motional and colligative properties as does water in bulk liquid state. This assumption is used in studies of volume regulation, transmembrane movement of solutes and electrical potentials, solute and solution motion, solute solubility and other phenomena. To get at the extent and the source of non‐ideally behaved water (an operational term dependent on the measurement method), we studied the motional and colligative properties of water in cells, in solutions of amino acids and glycine peptides whose surface characteristics are known, and in solution of bovine serum albumin, hemoglobin and some synthetic polypeptides. Solutions of individual amino acids with progressively larger hydrophobic side chains showed one perturbed water molecule (structured‐slowed in motion) per nine square angstroms of hydrophobic surface area. Water molecules adjacent to hydrophobic surfaces form pentagonal structural arrays, as shown by X‐ray diffraction studies, that are reported to be disrupted by heat, electric field, hydrostatic pressure and phosphorylation state. Hydrophilic amino acids demonstrated water destructuring (increased motion) that was attributed to dielectric realignment of dipolar water molecules in the electric field between charge groups. In solutions of proteins, several methods indicate the equivalent of 2–8 layers of structured water molecules extending beyond the protein surface, and we have recently demonstrated that induced protein conformational change modifies the extent of non‐ideally behaved water. Water self‐diffusion rate as measured in three different cell types was about half that of bulk water, indicating that most of the water in these cells was slower in motion than bulk water. In different cell types the extent of osmotically perturbed water ranged from less than half to almost all of the intracellular water. The assumption that essentially all intracellular water has ideal osmotic and motional behavior is not supported by the experimental findings. The non‐ideality of cell water is an operational term. Therefore, the amount of non‐ideally behaving water is dependent on the characteristics of water targeted, i.e. the measurement method, and a large fraction of it is explainable in mechanistic terms at a molecular level based on solute—solvent interactions.
RIBOSOME SYNTHESIS IN TETRAHYMENA: A QUANTITATIVE ANALYSIS
Authors: Larsen Leif K. , Andreasen Per H. , Kristiansen Karsten 
Published: September 2002

AbstractWe have performed a detailed quantitative analysis of the transcription and accumulation of ribosomal RNA and ribosomal protein mRNA in the ciliated protozoan Tetrahymena thermophila during changes in growth conditions, and found that: (1) nutritional downshifts lead to a rapid decrease in transcriptional activity whereas nutritional upshifts lead to rapid restoration of transcriptional activity, (2) starvation leads to decreased translation of ribosomal protein mRNA and (3) the rate of ribosomal protein mRNA degradation decreases after a nutritional upshift. We present evidence that the proximal promoters of two ribosomal protein genes and the ribosomal RNA gene compete for binding of nuclear factor(s) in vitro, suggesting that the coordinated regulation of these genes may involve a common set of transcriptional regulators.
EPIDERMAL GROWTH FACTOR RECEPTOR (EGF‐R) LOCALIZATION IN THE APICAL MEMBRANE OF THE ENTEROCYTES OF RAT DUODENUM
Authors: Montaner B. , Pérez‐Tomás R. 
Published: September 2002

The maintenance of gastrointestinal epithelium integrity requires a fine balance between proliferation and differentiation as well as protection against gastric acid secretion. Some growth factors, such as epidermal growth factor (EGF) and transforming growth factor alpha (TGF‐α), bind to epidermal growth factor receptor (EGF‐R) to exert these functions. The exact location of EGF‐R within the duodenal area is controversial and still not completely known.Immunohistochemical and Western blot techniques using a monoclonal anti‐EGF‐R antibody were performed on the adult rat duodenum.The duodenal enterocytes expressed EGF‐R in the apical membrane and in the supranuclear area along the length of the villuos. The Lieberkhüm crypts and Brunner's glands also showed a positive immunostaining. By Western blot analysis we identified in the duodenal scrape a band with an apparent molecular weight of 175kDa.Our results suggest a functional role for the luminal EGF and/or TGF‐α in the establishment and maintenance of the epithelial renewal, probably by stimulation of cell proliferation, differentiation and migration.
HYDROGEN PEROXIDE INDUCES APOPTOSIS IN HUMAN HEPATOMA CELLS AND ALTERS CELL REDOX STATUS
Authors: Li Ji , Huang Chung‐Yang , Zheng Rong‐Liang , Cui Kai‐Rong , Li Jian‐Feng 
Published: September 2002

AbstractDirect exposure of human hepatoma cell line SMMC‐7721 to hydrogen peroxide (H2O2) can induce apoptosis. Apoptosis induced by H2O2was inhibited by cycloheximide, actinomycin D, 3‐aminobenzamide, EGTA or Zn2+. H2O2can increase the level of intracellular Ca2+, downregulate GSH levels, slightly induce lipid peroxidation, and lead to change in the ratio of reduced ion components to oxidized ion components of cells. Analysis of flow cytometry indicates that H2O2decreases the level of Bcl‐2. The data indicate that H2O2‐induced apoptosis requires new mRNA and protein syntheses; H2O2can activate Ca2+/Mg2+‐dependent endonuclease leading to internucleosomal DNA fragmentation and activation of poly (ADP‐ribose) polymerase interfering with the energy metabolism of the cell. The H2O2downregulation of GSH may be more important for apoptosis than H2O2induction of lipid peroxidation, and the H2O2induced changes in redox status of the cell may be among the original events which lead up to other biochemical changes.
INHIBITION OF EARLY DNA‐DAMAGE AND CHROMOSOMAL ABERRATIONS BY TRIANTHEMA PORTULACASTRUM L. IN CARBON TETRACHLORIDE‐INDUCED MOUSE LIVER DAMAGE
Authors: Sarkar Alok , Pradhan Soumen , Mukhopadhyay Indranil , Bose Subrata K. , Roy Shyamal , Chatterjee Malay 
Published: September 2002

AbstractThe underlying molecular mechanisms of the antihepatotoxic activity of Trianthema portulacastrum by monitoring its effect on mouse liver DNA‐chain break, sugar‐base damage and chromosomal aberrations, during chronic or acute treatment with carbon tetrachloride (CCl4) have been studied. Daily oral feeding with the ethanolic extract (150mg/kg basal diet, per os) was given 2 weeks before CCl4treatment and continued until the end of the experiment (13 weeks). T. portulacastrum extract offer unique protection (P< 0.05–0.001) against the induction of liver‐specific structural‐type chromosomal anomalies 15, 30 or 45 days after the last CCl4insult, compared to control mice. This was further evidenced by extract‐mediated protection (15 days prior feeding following a single necrogenic dose of CCl4) of the generation of DNA chain‐break and Fe‐sugar‐base damage assays. The observed hepatoprotective mechanism could be due to its ability to counteract oxidative injury to DNA in the liver of mouse.
ROTOKINESIS, A NOVEL PHENOMENON OF CELL LOCOMOTION‐ASSISTED CYTOKINESIS IN THE CILIATE TETRAHYMENA THERMOPHILA
Authors: Brown Jason M. , Hardin Clyde , Gaertig Jacek 
Published: September 2002

AbstractThe mechanism responsible for final cell separation at the end of cytokinesis is currently unknown. Knockout strains of the ciliate, Tetrahymena thermophila lacking the kinesin‐II homologous molecular motors, Kin1p and Kin2p are paralyzed due to their complete loss of cilia and undergo frequent cytokinesis failures. Observations of live dividing cells revealed that cleavage furrow ingression is normal in kinesin‐II double knockout cells until the final stage of cell separation (Brown et al., 1999). During closer inspection of dividing cells using video differential interference contrast microscopy, we found that wild‐type cells undergo an extremely complex motile behavior near the end of cytokinesis. This process, which we have named rotokinesis, appears to facilitate the physical separation of daughter cells. Here we present recent work onTetrahymena rotokinesis, and review studies in other organisms which suggest that the use of cell locomotion in the completion of cytokinesis is a general phenomenon of motile cell types.
FROM HORMONE SIGNAL, VIA THE CYTOSKELETON, TO CELL GROWTH IN SINGLE CELLS OF TOBACCO
Authors: Vissenberg Kris , Quelo Anne‐Helene , van Gestel Kristin , Olyslaegers Geert , Verbelen Jean‐Pierre 
Published: September 2002

AbstractCultured mesophyll protoplasts of Nicotiana tabacum L. can be hormonally induced into different developmental pathways. In a medium containing auxins (NAA) and cytokinins (BAP) cells divide and eventually give rise to calli. When only auxins are present cells elongate and finally differentiate into very long tubular cells. We focused on the sequence of events leading to elongation. When cultured in a high (1mg/l) auxin concentration elongating cells seem to pass a certain threshold and increase their nuclear DNA up to about 16C. Cells cultured in a low (0.065mg/l) auxin concentration only have C‐values up to 4C, are unable to pass this threshold and finally fail to elongate. Besides the concentration dependence of the auxin signal, the efflux of auxin seems to be necessary for elongation since addition of TIBA drastically reduces the amount of elongating cells. Concomitant with the changes in nuclear physiology, auxin‐induced axiality is seen as sequential rearrangements of microtubules and actin‐filaments and of cell wall cellulose microfibrils from ‘randomly’ arranged in spherical cells to an orientation perpendicular to the long axis of elongating cells.
INTERACTION OF PLANT POLYSOMES WITH THE ACTIN CYTOSKELETON
Authors: Klyachko N. , Aksenova L. , Dunaeva M. , Kulikova A. 
Published: September 2002

AbstractProtein composition and functional activity of various polysome subpopulations isolated from Vicia faba L. leaves and Triticum aestivum L. and Hordeum vulgare L. seedlings were studied. Membrane‐ and cytoskeleton‐bound polysomes were more active in the wheat germ cell‐free translational system than free polysomes. Several non‐ribosomal proteins were detected in the polysome preparations by gel electrophoresis and Western blot analysis: (1) a canonical actin of mol wt 42kDa; (2) a 40kDa protein, demonstrating affinity for ribosomes, sharing some determinants with actin, and present predominantly in the subpopulations of bound polysomes; and (3) an acidic ribosome‐associated p40 evenly distributed between free and bound polysomes. The possibility of involvement of these proteins in interactions between polysomes and the actin cytoskeleton is discussed.
APOPTOTIC AND NON‐APOPTOTIC MODES OF PROGRAMMED CELL DEATH IN MCF‐7 HUMAN BREAST CARCINOMA CELLS
Authors: Amin Farhana , Bowen Ivor D. , Szegedi Zsolt , Mihalik Rudolf , Szende Bela 
Published: September 2002

AbstractApoptosis is a specific mode of programmed cell death (PCD), recognized by characteristic morphological and molecular changes. Here we present evidence for a non‐apoptotic type of PCD in human MCF‐7 breast carcinoma cells. We used TNF‐α and tyrphostin AG213 to induce apoptotic and non‐apoptotic cell death respectively in vitro. Microscopic and immunohistochemical studies, together with DNA analysis and flow cytometric analysis of p53 and bcl‐2 oncogene expression, revealed some novel characteristics of non‐apoptotic cell death. We show here for the first time some of the biochemical features of an experimentally induced non‐apoptotic PCD and emphasize the distinct biochemical events leading to apoptotic and non‐apoptotic PCD.
EVIDENCE OF TYPE II ESTROGEN RECEPTOR IN HUMAN OSTEOBLAST‐LIKE CELLS
Authors: Toesca A. , Pagnotta A. , Specchia N. 
Published: September 2002

AbstractOsteoblast‐like cells isolated from human bone bioptic specimens were characterized and analysed for the presence of type II estrogen receptor (type II EBS). The amount of type II EBS was measured by a whole‐cell assay at 4°C for 2.5h using [3H]‐estradiol as tracer. Saturation analysis, used to investigate the binding characteristic of type II EBS, resulted in a sigmoid curve. Scatchard analysis showed the binding affinity of the estrogen receptor, yelding a concave plot. The dissociation constant (Kd), determined from the [3H]‐estradiol concentration required for half saturation was about 12±2nM (SD). The number of type II EBS, estimated at maximum binding, was 197,000±8800 sites per cell. If the regulation of the receptor by flavonoids would be confirmed, the evidence of type II EBS in osteoblast‐like cells could suggest a direct action of ipriflavone and others flavonoids on bone density in postmenopausal osteoporosis.
MODES OF CELL DEATH IN THE HYPOPHARYNGEAL GLAND OF THE HONEY BEE (APIS MELLIFERA L)
Authors: de Moraes Regina L.M. Silva , Bowen Ivor D. 
Published: September 2002

AbstractDifferent modes of cell death have been revealed in the regressing hypopharyngeal glands of worker honey bees. The hypopharyngeal gland, which is well developed in young nursing bees to produce protein for larval food, was seen to regress naturally in foraging adult worker bees. A range of techniques including histology, cytochemistry, in situ TUNEL, Annexin V and Comet assays indicated that cells within the gland demonstrate progressive symptoms of apoptosis, necrosis and a vacuolar form of programmed cell death. The latter mode of cell death did not display chromatin margination, but was accompanied by an enhanced level of autophagic and hydrolytic activity in which a cytosolic source of acid phosphatase became manifest in the extra‐cisternal spaces. Normal and annexin‐positive cells were found to occur in the younger nursing bees, whilst necrosis and an aberrant vacuolar type of apoptosis predominated in the older foraging bees. The relevance of these results to the classification of programmed cell death is discussed.
TEMPORAL VARIATIONS IN PROTEIN TYROSINE PHOSPHATASE ACTIVITY DURING CELL PROLIFERATION AND DIFFERENTIATION
Authors: Calvert‐Evers J. L. , Hammond K. D. 
Published: September 2002

ABSTRACTCellular oscillations in total extractable protein content and protein tyrosine phosphatase activity were analysed in proliferating and differentiating human acute promyelocytic leukaemic (HL‐60) cell extracts. Differentiation was induced along the granulocytic pathway using all‐trans retinoic acid (ATRA). High frequency rhythms with distinct, well defined waveforms of varying amplitude were observed for both the total protein content and for the enzyme activity of protein tyrosine phosphatase (PTP). Linear correlation analysis showed that there was no obvious relationship between the protein content and the corresponding PTP activity, suggesting that the periodic variations between these two components are relatively independent of each other. ATRA significantly altered the characteristics of the rhythms with respect to the period and amplitude and had a dampening effect on the oscillatory pattern of PTP activity. Modulation of such characteristics may be of significance with respect to the regulation of the differentiation processes and the possible reversal of transformation.
CHANGES IN THE EXPRESSION OF SMALL INTESTINE EXTRACELLULAR MATRIX PROTEINS IN STREPTOZOTOCIN‐INDUCED DIABETIC RATS
Authors: Sánchez Sara S. , Genta Susana B. , Aybar Manuel J. , Honoré Stella M. , Villecco Evelina I. , Sánchez Riera Alicia N. 
Published: September 2002

AbstractDiabetes mellitus is characterized by anatomical and functional alterations of the intestinal tract. However, the aetiology of these disturbances remains unclear. The aim of the present work was to investigate the effects of diabetes on the expression of laminin‐1 and fibronectin in the small intestine of Streptozotocin (STZ)‐induced diabetic rats. The Western immunoblotting of the extracts from the small intestine revealed that experimental diabetes resulted in a marked increase in the intensity of the bands corresponding to laminin‐1 and fibronectin. Immunohistochemical studies demonstrated a strong labelling to these two extracellular matrix (ECM) proteins in the small intestine of diabetic rats, mainly localized in the smooth muscle layer. These results occur together with a thickening of the basement membrane (BM) of the smooth muscle cells, demonstrated by transmission electron microscopy (TEM). We propose that the accumulation of ECM proteins in the smooth muscle layer may be an effect mediated by hyperglycaemia, since insulin treatment of diabetic rats reversed this accumulation. These results could provide information on the potential role of the ECM in the intestine, an organ which is known to exhibit important alterations in diabetes.
Science with NIFS, Australia's First Gemini Instrument
Authors: McGregor Peter J. , Dopita Michael , Wood Peter , Burton Michael G. 
Published: September 2002

AbstractThe Near-infrared Integral Field Spectrograph (NIFS) will beAustralia’s first Gemini instrument. NIFS is a near-infrared, imaging spectrograph that will be used with the ALTAIR facility adaptive optics system on Gemini North to perform near-diffraction-limited imaging spectroscopy over a 3·0″ × 3·0″ field of view with 0·1″ wide slitlets and a spectral resolving power of ˜5300. NIFS will operate in the wavelength range from 0·94–2·50 µm where ALTAIR delivers its greatest gains. Its primary purpose is to study moderate-surface-brightness structures around discrete objects that are revealed at high spatial resolution by ALTAIR. NIFS will address a wide range of science from studies of Galactic star formation and the Galactic centre to the nature of disk galaxies at z ˜ 1. Studies of the demographics of massive black holes in galactic nuclei and studies of the excitation conditions in the inner narrow-line regions of Seyfert galaxies have been identified as two core NIFS programs. These and other science drivers for NIFS are discussed.
Atmospheric Modelling of the Companion Star in GRO J1655-40
Authors: Buxton Michelle , Vennes Stephane 
Published: September 2002

AbstractWe have measured the rotational velocity of the companion star to be Ʊrot sin i= 80 ± 10 km s ˗1 (1σ) by fitting Kurucz model spectra to our observed spectrum of the black-hole candidate GRO J1655–40. From this we have calculated q = 0·31 ± 0·08, the mass of the compact object to be M1 = 7·91 ± 3·79 Mô (1σ) and for the companion starM2 = 2·76 ± 1·79 Mô (1σ), which is consistent with previous studies. We have also determined Teff = 6500 ± 50 K and [Fe/H] = −0·15 +0·15-0·10.
What do Quasars Look Like?
Authors: Francis Paul J. 
Published: September 2002

AbstractMicrolensing observations may give us the first nano-arcsecond scale information about the structure of quasars. I review what is currently known about quasars on these scales, highlighting the principal uncertainties. I cover both the continuum emission and the broad line region. I conclude that little is firmly known about the structure of quasars.
Cosmological Parameter Survey Using the Gravitational Lensing Method
Authors: Premadi Premana W. , Martel Hugo , Matzner Richard , Futamase Toshifumi 
Published: September 2002

AbstractUsing a multiple-lens plane algorithm, we study light propagation in inhomogeneous universes for 43 different COBE-normalized Cold Dark Matter models, with various values of the density parameter Ω0, cosmological constant λ0, Hubble constant H0, and rms density fluctuation σ8.We performed a total of 3798 experiments, each experiment consisting of propagating a square beam of angular size 21.9″ 21.9″ composed of 116 281 light rays from the observer up to redshift z = 3. These experiments provide statistics of the magnification, shear, and multiple imaging of distant sources. The results of these experiments might be compared with observations, and eventually help constrain the possible values of the cosmological parameters. Additionally, they provide insight into the gravitational lensing process and its complex relationship with the various cosmological parameters.
Radio Images of the Globular Cluster 47 Tucanae
Authors: McConnell D. , Deacon R. , Ables J. G. 
Published: September 2002

AbstractWe present deep ATCA radio images of the globular cluster 47 Tucanae made at 1.4 and 1.7 GHz and identify 9 compact sources in the cluster core with 11 pulsars. At present there are several pulsars for which pulse timing analyses have not yet yielded precise positions. We examine other sources in the image, and on the basis of their spectral index find two that would possibly correspond to the pulsars with undetermined positions.
Fifty Years of Research on Stellar Atmospheres
Authors: Mihalas Dimitri 
Published: September 2002

AbstractI would like to begin by saying what a pleasure it is for me to be here. For my entire adult life I have wanted to come to Australia. Actually, I have been invited to visit here twice before, but each time I was thwarted by circumstances beyond my control. But this time I was determined to (a) prove that the third time is indeed the charm, and (b) pay homage to Walter Stibbs, who in my mind is the epitome of a scholar and a gentleman. I have known Walter as colleague, teacher, and friend, not to mention as an inspiration, both professional and personal. So I am here today to try to give some sense of progress in the study of stellar atmospheres, a field that Walter has graced with his virtuosic touch. I will follow an unabashedly personal path, describing the development as I experienced it. I will focus almost entirely on early-type stars, where we may reasonably expect the atmospheric layers to be homogeneous, and in radiative equilibrium. Only at the end will I mention our nearest stellar neighbor, the Sun, which, because we can study it in so much detail, offers counterexamples to almost all of the the theory that works so well for early-type stars. I offer apologies in advance to anyone this approach may offend.
The Mechanisms for the Generation of Pulsar Radio and High-energy Emission
Authors: Machabeli George Z. 
Published: September 2002

AbstractThe recent theory of propagation and generation of waves in a pulsar’s magnetosphere is discussed. In particular we consider models of pulsar radio emission due to plasma instabilities. Wave–particle interactions can lead to quasilinear diffusion increasing a particle’s pitch-angle. The recent model of γ-ray emission from synchrotron radiation as a result of quasilinear diffusion is discussed.
Intraday Variability in Northern Hemisphere Radio Sources
Authors: Krichbaum T. P. , Kraus A. , Fuhrmann L. , Cimò G. , Witzel A. 
Published: September 2002

AbstractWe summarise results from flux density monitoring campaigns performed with the 100 m radio telescope at Effelsberg and the VLA during the past 15 yrs. We briefly discuss some of the statistical properties from now more than 40 high declination sources (δ ≥ 30°), which show intraday variability (IDV). In general, IDV is more pronounced for sources with flat radio spectra and compact VLBI structures. For 0917+62, we present new VLBI images which suggest that the variability pattern is modified by the occurrence of new jet components. For 0716+71, we show the first detection of IDV at millimetre wavelengths (32 GHz). For the physical interpretation of the IDV phenomenon, a complex source and frequency dependent superposition of interstellar scintillation and source intrinsic variability should be considered.