bluuebunny/crossref_metadata_2025 huggingface dataset:
Differentiation and programmed cell death in SA‐45 tumour treated with bone inducer.
Authors: Arshavskaya T. , Erenpreisa J. , Roach H.
Published: September 2002

The relationship between differentiation and concerted cell death was studied using ultrastructural, histochemical and immunochemical methods in solid rat fibrosarcoma Sa‐45 grown in the presence of demineralized bone matrix. The control tumour consisted mostly of undifferentiated cells with few poorly or moderately differentiated cells. In the presence of the inducer, cells with a more differentiated pattern appeared in the surrounding area. The proliferative activity in the presence of the inducer was 3 to 5 times lower but the apoptotic index was higher than in the controls. However, complete differentiation was induced only in stromal cells, whereas the parenchymal cells showed signs of enhanced but incomplete differentiation. The ultrastructural signs of programmed cell death progressed in them faster than the corresponding features of maturation, thus leaving differentiation incomplete.
Trafficking of immunoglobulin receptors in epithelial cells:signals and cellular factors
Authors: Hunziker Walter , Fumey C. , Höning S. , Kamel L. C.
Published: September 2002

A typical feature of epithelial cells is the polarized distribution of their respective plasma membrane proteins. Apical and basolateral proteins can be sorted both in the trans‐Golgi network and endosomes, or in both locations. Inclusion into basolateral carriers in the TGN requires the presence of distinct cytoplasmic determinants, which also appear to be recognized in endosomes. Inactivation of the basolateral sorting information leads to the efficient apical delivery, probably due to the unmasking of a recessive apical signal. Factors associated with the cytosolic face of organelles probably not only recognize these signals to mediate the inclusion of the proteins into the correct transport vesicles, but also target the carriers to the corresponding plasma membrane domain. Our interest has focused on analyzing at the molecular level how epithelial MDCK cells generate and maintain a polarized phenotype, taking advantage of immunoglobulin receptors to study the biosynthetic and endocytic pathways and the corresponding sorting events.
REVERSIBLE REARRANGEMENT OF VIMENTIN‐TYPE INTERMEDIATE FILAMENTS IN CULTURED HUMAN SKIN FIBROBLASTS FROM PATIENTS WITH LYSOSOMAL STORAGE DISEASES
Authors: Tatiana Ivleva , German Wiederschain
Published: September 2002

Immunofluorescence microscopy shows that unlike cytoplasmic microtubules (MT), vimentin‐type intermediate filaments (IF) are collected into ring‐shaped structures in affected fibroblasts. The altered IF organization could be observed in monolayers of polarized fibroblasts in the prolonged stationary growth phase and after replating ‐ upon their initial spreading. Transition from a discoid to an extended cellular form is accompanied by centrifugal dislocation of ring‐shaped IF structures towards the cell's active edge with gradual restoration of the radial fibrillar vimentin network. Spreading of affected cells occurred more slowly than that of control fibroblasts.
Presence of gelatinase A and etalloelastase type protease at the plasma membrane of human skin fibroblasts. Influence of cytokines and growth factors on cell‐associated metalloendopeptidase levels
Authors: Beranger Jean‐Yves , Godeau Gaston , Frances Camille , Robert Ladislas , Hornebeck William
Published: September 2002

Gelatinase A and elastase type proteinase (Homsy, et al., 1988) present at plasma membranes of human skin fibroblasts (HSF) were separated by anion exchange chromatography on a DEAE Tris acryl M column. Elastase type proteinase (HSFE1) was able to convert 72 kDa progelatinase A to a lower 66 kDa M.W. active enzyme. Several cytokines (IL‐1β, 1L4, IL6), interferon γ (IFN γ) and tumor growth factor β (TGFβ) were studied for their ability to modify the levels of those plasma membrane associated proteinases. Among these mediators, only IL‐1β was found to enhance the amounts of HSF membrane‐bound HSFE1 and Gelatinase A.
Increase in cytoskeletal actin induced by inositol 1,4‐bisphosphate in saponin‐permeated pig platelets
Authors: Huang Cai , Liang Nian‐ci
Published: September 2002

Inositol 1,4‐bisphosphate (IP2), which rapidly accumulates during cell activation, strongly stimulates an increase in cytoskeletal actin in saponin‐permeated platelets, and the effect is insensitive to 5′‐Chloro‐5′‐deoxyadenosine. Within 10 s, the amount of cytoskeletal actin in platelets rapidly increases by 41%, and then slowly increases further. IP2 induces the increase in cytoskeletal actin in a dose‐dependent manner. The half‐maximal effect requires approximately 2 μM of IP2 Inositol 1,4,5‐ triphosphate, the messenger for Ca2+ release, causes the increase in cytoskeletal actin, but is less effective than IP2. Inositol 1‐monophosphate and inositol 2‐monophosphate have no effect on cytoskeletal actin. Phorbol 12‐myristate 13‐acetate, which has been shown to activate IP3 5′‐phosphatase through protein kinase C, stimulates the increase in cytoskeletal actin. Spermine, an inhibitor of IP3 5′‐phosphatase, inhibits the thrombin stimulated increase in cytoskeletal actin. These results suggest that IP2 may be a messenger that controls the organization of actin filaments during cell activation. This study presents the first evidence for IP2 as a messenger during cell activation.
Effect of extracellular K+ on hatching and outgrowth of mouse blastocysts in vitro.
Authors: Jin Zhengzhu , Jin Meishan , Roomans Godfried M.
Published: September 2002

The dependence of blastocyst development on the extracellular Na+/K+ ratio was investigated in an in vitro system. Hatching and outgrowth of mouse blastocysts was enhanced at Na+/K+ ratios between 3 and 10 compared to the ratio of about 25 typical for most culture media and serum. At a Na+/K+ ratio of 2, blastocyst hatching and outgrowth were inhibited. The requirement of blastocyst development for relatively high extracellular K+ concentrations agrees with the fact that K+ concentrations in oviduct and uterine secretions are higher than in serum. The findings can also be relevant in optimizing in vitro culturing techniques for blastocysts.
Changes in the nature of P‐glycoprotein gene transcripts during the development of multidrug resistance in CHO cells.
Authors: Vickers S. E. , Warr J. R.
Published: September 2002

We have studied the nature of P‐glycoprotein gene transcripts in multidrug resistant Chinese hamster ovary cell lines selected in vincristine. Using a novel, 35S based, reverse transcription polymerase chain reaction assay, we have shown that there is a considerable increase in the level of pgp2 gene transcripts, with levels rising to a hundred fold those observed in sensitive control cells. The level of pgp1 gene transcripts was raised five fold. The levels of pgp3 gene transcripts were close to the limits of detection by the assay, but were increased in the more highly resistant cell lines. An increase in the size of the P‐glycoprotein gene transcript was also observed in some of the resistant cell lines.
Secretion of TNF‐α from macrophages following induction with a lignin derivative.
Authors: Sorimachi Kenji , Akimoto Kazumi , Tsuru Keiko , Nagashima Shigeki , Ieiri Tamio , Niwa Akira
Published: September 2002

Macrophages derived from rat bone marrow were treated with macrophage colony stimulating factor (M‐CSF) to obtain a sufficient number of cells for the tumor necrosis factor (TNF‐α) assay. The present study has been designed to investigate whether the production of TNF‐α, which induces multinucleated giant cell formation, is regulated by polyanions such as lignin derivatives. ELISA for TNF‐α showed that the polyanion induced TNF‐α production by macrophages. The secretion of TNF‐α from the cells reached a maximum at 3‐6 h, and then showed a slight decline. Northern blotting of TNF‐α mRNA showed that the amount of TNF‐α reached a maximum within 1 h of macrophage culture in the presence of a lignin derivative. On the other hand, TNF‐α mRNA was undetectable in the control cells. It was concluded that stimuli such as that provided by lignin derivatives increases the amount of TNF‐α mRNA, which is then followed by translation of TNF‐α.
Hyperthermic stress modulates the functions of rat liver glucocorticoid receptor
Authors: Matić Gordana , Kipić Jasmina , Ristić Biljana , Dundjerski Jadranka , Trajković Divna
Published: September 2002

A mild whole body hyperthermic stress causes a rapid and reversible reduction of rat liver glucocorticoid receptor (GR) binding capacity and affects the stability of the GR‐DNA complexes formed after thermal transformation of the receptor. These changes appear to be physiologically relevant, since they are accompanied by a decrease in dexamethasone induction of hepatic tyrosine aminotransferase (TAT). In spite of the decreased rate of the GR degradation in liver cytosol of hyperthermic as compared to control rats, the total amount of the GR and its proteolytic products recognized by BuGR2 monoclonal antibody was found to be lower in the former cytosol, but higher in the respective nuclei.
HETEROGENEITY IN RADIOSENSITIVITY OF HUMAN DIPLOID FIBROBLASTS FROM KELOIDS AND NORMAL SKINS
Authors: MA SHIUH , FANG RONG‐HWANG , CHANG WUSHOU P.
Published: September 2002

Colony‐forming ability was employed in evaluating the susceptibility toin vitrogamma ionizing radiation in human diploid skin fibroblasts (HDF). Twelve pairs of HDF, each composed of fibroblasts from excised keloid lesion and local normal skin tissue as its control, were studied in patients with clinically persistent keloids. Parameters of radiosensitivity, both D0and D10, and growth kinetics were examined. The radiosensitivity in three of the 12 keloids (25%) were demonstrated significantly increased than their counterpart controls, even though no difference in growth kinetics in between. Moreover, a broad range in the radiosensitivity of fibroblast cells was demonstrated and it is suggested that there is a great heterogeneity of cellular response to radiation in HDF.
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

It 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.
LOCALIZATION AND IDENTIFICATION OF GALACTOSE/N‐ACETYLGALACTOSAMINE AND SIALIC ACID‐CONTAINING PROTEINS IN CHINESE HAMSTER METAPHASE CHROMOSOMES
Authors: MYLLYHARJU JOHANNA , NOKKALA SEPPO
Published: September 2002

Four lectins were used to recognize galactose/N‐acetyl‐galactosamine (Gal/GalNAc) and sialic acid residues in proteins of Chinese hamster metaphase chromosomes. In situ binding pattern of a fluorescein isothiocyanate‐labelled (Gal/GalNAc)‐specific lectin Sophora japonica agglutinin (SJA) showed that chromosomal SJA‐binding proteins are primarily localized to the helically coiled substructure of chromatids. Numerous SJA‐binding proteins were identified in Western blots of chromosomal proteins, their molecular weights ranging from 26 to 200kDa. Another Gal/GalNAc‐specific lectin, peanut agglutinin (PNA), with a slightly different sugar binding specificity, did not bind to Chinese hamster metaphase chromosomes, and in Western blots only two chromosomal protein bands were faintly stained. The in situ labelling patterns of two sialic acid‐specific lectins, Maackia amurensis (MAA) and Sambucus nigra (SNA) agglutinins, both showed that the helically coiled substructure of chromatids is also enriched in sialylated proteins. In Western blot analysis 11 MAA‐binding protein bands with molecular weights ranging from 54 to 215kDa were identified, while SNA only bound to one protein band of 67kDa. MAA and SNA are specific for α (2|ad3)‐ and α (2|ad6)‐linked sialic acid residues, respectively. Thus, it is likely that α (2|ad3)‐linked sialic acid residues are more common in chromosomal proteins than α(2|ad6)‐linked sialic acid residues. These data suggest that Gal/GalNAc and sialic acid‐containing glycoproteins exist in metaphase chromosomes and that these proteins may have a role in the formation of higher order metaphase chromosome structures.
TERTIARY STRUCTURE OF THE HEPATIC CELL PROTEIN FIBRINOGEN IN FLUID REVEALED BY ATOMIC FORCE MICROSCOPY
Authors: TAATJES DOUGLAS J. , QUINN ANTHONY S. , JENNY RICHARD J. , HALE PAUL , BOVILL EDWIN G. , MCDONAGH JAN
Published: September 2002

Fibrinogen participates in important cellular physiological processes, such as cell adhesion and blood clotting. Although the primary and secondary structures of fibrinogen are known, its tertiary structure is yet to be determined. In attempts to understand the tertiary structure of this important hydrated cellular and plasma membrane protein, the present study using atomic force microscopy was carried out. The techniques presented in this manuscript may also be applicable to enhance the imaging of live cells as well as their subcellular components. The authors have imaged fibrinogen by Tapping Mode atomic force microscopy in fluid. Purified human fibrinogen, together with 15‐nm colloidal gold particles serving as an internal calibration standard, were adhered to a poly‐l‐lysine substrate on freshly cleaved mica. Atomic force microscopy images were obtained using oxide‐sharpened silicon nitride probes, either unaltered or with an electron beam deposited extended tip. Although various structures were observed, the predominant forms consisted of a bi‐ or trinodular slightly curved linear shape. Approximately 300 of these structures were observed with six different tips (1 unaltered and 5 electron beam deposited) and their lengths and heights were analyzed. The mean length of the fibrinogen molecules was 65.8nm and the mean height was 3.4nm. The quantitative measurements were little influenced by the shape of the tip, whereas the sharper electron beam deposited tips seemed to produce qualitatively superior images.
GROWTH HORMONE RECEPTOR GENE EXPRESSION ON HUMAN LYMPHOCYTIC AND MONOCYTIC CELL LINES
Authors: Derfalvi Beata , Szalai Csaba , Mandi Yvette , Kiraly Andras , Falus Andras
Published: September 2002

The potential effect of growth hormone (GH) in tumorigenesis, particularly in acute leukemia is controversial. Human growth hormone has the ability to influence certain immune functions; the majority of immune cells express growth hormone receptor (GHR) on plasma membranes. We determined GHR gene expression on different human lymphocyte (JURKAT, CESS) and monocyte (U937, THP1) cell lines by reverse transcriptase polymerase chain reaction analysis of GHR mRNA after stimulating the cells with phytohaemagglutinin or phorbolester, human growth hormone and with a combination of these. The receptor gene expression showed differences; in the U937 and CESS cell lines only the stimulants were able to induce GHR mRNA expression; in the case of JURKAT cells even the hormone alone had the ability to express its own receptor gene. Both the increased TNF‐α production of U937 (but not that of THP1 cells), and the decreased proliferation of JURKAT cells in response to GH stimuli also prove the presence of biologically active GHR on the cell surface. Our data suggest asymmetric interaction between GH or phorbolester‐induced signal pathways in U937 cells sharply depending on the temporal sequence of treatments. THP1 monocytes showed no gene expression in response to any of the stimulants. The phenomenon that certain human lymphoid and monocytoid cell lines at different levels of cell differentiation are able to express the GH receptor gene could have importance in the rhGH therapy.
SCYPHOZOAN JELLYFISH'S MESOGLEA SUPPORTS ATTACHMENT, SPREADING AND MIGRATION OF ANTHOZOANS' CELLS IN VITRO
Authors: Frank Uri , Rinkevich Baruch
Published: September 2002

Mechanically and enzymatically dissociated cells from five anthozoan species were laid on seven substrates in vitro. Cells were taken from two sea anemones (Aiptasia sp. and Anemonia sulcata), a scleractinian coral (Stylophora pistillata) and two alcyonacean corals (Heteroxenia fuscescence andNephthea sp). Substrates tested: glass (coverslips), plastic (uncoated tissue culture plates), type IV collagen, gelatin, fibronectin, mesoglea pieces from the scyphozoan jellyfish Rhopilema nomadica and acetic acid extract of jellyfish mesoglea. Except for the mesoglea pieces, cells did not respond to any one of the other substrates, retaining their rounded shape. Following contact with mesoglea pieces, cells attached and spread. Subsequently they migrated into the mesogleal matrix at a rate of 5–10μm/h during the first 2–5h. No difference was found between the behavior of cells from the five different cnidarian species.
SYNAPTIC MODULATION OF NEURONAL COUPLING
Authors: Hatton Glenn I.
Published: September 2002

Electrotonic coupling among neurons in the vertebrate, and more specifically the mammalian, brain has now been demonstrated to exist in all major brain subdivisions and in the spinal cord. For many of these brain areas, recent studies have investigated the possibilities of modulation of that coupling by synaptically released transmitters and/or neuromodulators. Reviewed here is the evidence for coupling, the synaptically related factors that play roles in up‐ or downregulation of this type of intercellular interaction and, to the extent that they have been investigated, the intracellular mechanisms operative in changing the extent of coupled networks in the brain. The functional significance of coupling and its modulation is discussed for some of these areas.
COMMON THEMES IN PERIPHERAL NEUROPATHY DISEASE GENES
Authors: Snipes G. Jackson , Orfali Wayel
Published: September 2002

After a century of study, mutations in connexin32, peripheral myelin protein22, and protein zero are now known to culminate in the prototypical phenotype of Charcot‐Marie‐Tooth disease. Many of these mutations have been modeled in rodents and in tissue culture. Consequently, structure—function predictions for these mutations are now possible and detailed analyses of many of them are ongoing. Despite the marked differences in the functions of these three proteins, it is profitable to consider the many similarities between them, including the types of mutational mechanisms and their effects on myelin structure and function. Accordingly, the biology and genetics of Charcot‐Marie‐Tooth disease and other inherited peripheral neuropathies due to mutations in these proteins are reviewed.
CELL COUPLING IN THE RETINA: PATTERNS AND PURPOSE
Authors: Becker David , Bonness Viola , Mobbs Peter
Published: September 2002

Gap junction channels (electrical synapses) are a major component of the central nervous system mediating both electrical and metabolic coupling between neurons and glia. Their roles are as diverse as the cell types in which they are expressed and only some of these are reviewed here. In the adult the plastic nature of the gap junction channel allows for changes in the writing of the retinal circuitry that optimize visual processing to suit ambient lighting conditions. Gap junctional communication has been proposed to play a key role in embryonic development in general and in particular during the development of the retina where its roles may include control of neurogenesis, cell specification, synaptogenesis, and the synchronization of the spontaneous electrical activity required for the sharpening of central visual projections. Here we review gap junctional coupling within the retina and present data correlating gap junction expression with development events in the chick retina.
RIBOSOME SYNTHESIS IN TETRAHYMENA: A QUANTITATIVE ANALYSIS
Authors: Larsen Leif K. , Andreasen Per H. , Kristiansen Karsten
Published: September 2002

We 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.
DIVERSIFICATION OF GAP JUNCTION PROTEINS (CONNEXINS) IN THE CENTRAL NERVOUS SYSTEM AND THE CONCEPT OF FUNCTIONAL COMPARTMENTS
Authors: Dermietzel Rolf
Published: September 2002

This review describes recent progress in the identification of the molecular composition of gap junction proteins (connexins) in brain tissue. First, a general overview of gap junction function and the composition of the hemichannels (connexons) is given. Then the question of diversity of gap junction channels in the nervous system is addressed and its functional implications are discussed. Based on recent findings of gap junction mediated cell‐to‐cell communication we attempt to refine the concept of functionally coupled compartments in the brain. This conceptual introduction passes on to a detailed description of the coupling efficiency in glial and neuronal compartments with emphasis on innovative perspectives that allow a better understanding of gap junction function in the brain.
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

Direct 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

The 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

The 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.
CELL TYPE‐DEPENDENT COLLAGEN‐TYPE RECOGNITION BY CELL RECEPTORS
Authors: Sadofiev L. A. , Nikolaenko N. S. , Kalmykova N. V. , Podgornaya O. I.
Published: September 2002

Affinity chromatography of a number of cell types on collagens I and III reveals three proteins with MRof 250, 170 and 140kDa. These proteins are able to discriminate between types I and III, but not types III and IV. Collagen‐type recognition is therefore characteristic for cells of connective tissue origin. Polyclonal antibodies (Ab) raised against 170 and 140kDa polypeptides and used in immunofluorescence show membrane localisation for both, with their distribution being similar to each other and to the distribution of the integrin β1 chain. Abp140 and commercial monoclonal antibodies against α2chain stain a band of the same molecular mass as from purified collagen binding proteins from liver cells, indicating that the 140kDa protein is probably the α2integrin chain. The α2chain containing integrins are therefore able to discriminate collagen types I and III and collagen type recognition by this receptor is cell‐type dependent.
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

Cultured 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

Protein 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

Apoptosis 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

Osteoblast‐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

Different 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.
POLYPLOID GIANT CELLS PROVIDE A SURVIVAL MECHANISM FOR p53 MUTANT CELLS AFTER DNA DAMAGE
Authors: Illidge Timothy M. , Cragg Mark S. , Fringes Birgitta , Olive Peggy , Erenpreisa Jekaterina A.
Published: September 2002

The relationships between delayed apoptosis, polyploid ‘giant’ cells and reproductive survivors were studied in p53‐mutated lymphoma cells after DNA damage. Following severe genotoxic insult with irradiation or chemotherapy, cells arrest at the G2‐M cell cycle check‐point for up to 5 days before undergoing a few rounds of aberrant mitoses. The cells then enter endoreduplication cycles resulting in the formation of polyploid giant cells. Subsequently the majority of the giant cells die, providing the main source of delayed apoptosis; however, a small proportion survives. Kinetic analyses show a reciprocal relationship between the polyploid cells and the diploid stem line, with the stem line suppressed during polyploid cell formation and restituted after giant cell disintegration. The restituted cell‐line behaves with identical kinetics to the parent line, once re‐irradiated. When giant cells are isolated and followed in labelling experiments, the clonogenic survivors appear to arise from these cells. These findings imply that an exchange exists between the endocyclic (polyploid) and mitotic (diploid or tetraploid) populations during the restitution period and that giant cells are not always reproductively dead as previously supposed. We propose that the formation of giant cells and their subsequent complex breakdown and subnuclear reorganization may represent an important response of p53‐mutated tumours to DNA damaging agents and provide tumours with a mechanism of repair and resistance to such treatments.
PROBLEMS ASSOCIATED WITH THE STUDY OF CELLULAR OSCILLATIONS
Authors: Gilbert D. A. , Ferreira G. M. N.
Published: September 2002

Data from the article by Brodsky et al. (2000) have been examined in order to confirm that the fluctuations they report are not random but have a rhythmic basis, thereby verifying their conclusions regarding the existence of periodicity in protein synthesis. Reasons are outlined why oscillations should be expected in all cellular biochemical studies. Associated practical problems are briefly discussed together with comments on the validity and value of less rigorous methods of analysis. The subject of aliasing is raised as justification for doubting the validity of much published data, especially where periodicity has not been suspected. The existence of oscillations indicates the need for a thorough re‐evaluation of our understanding of cell biochemistry.
TEMPORAL VARIATIONS IN PROTEIN TYROSINE PHOSPHATASE ACTIVITY DURING CELL PROLIFERATION AND DIFFERENTIATION
Authors: Calvert‐Evers J. L. , Hammond K. D.
Published: September 2002

Cellular 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.
THE LIVING CELL: A COMPLEX AUTODYNAMIC MULTI‐OSCILLATOR SYSTEM?
Authors: Gilbert Don , Lloyd David
Published: September 2002

Life cannot be simply defined in biochemical terms but it is associated with autodynamic behaviour. This fact implies that all aspects of cell biology should be viewed in terms of the resultant temporal features. Theoretical arguments indicate that the dynamic state can be explained only by the existence of periodicity. In accordance with this view, experimental evidence indicates the existence of multiple oscillators and at least some are highly complex, implying that failure to understand aspects of cell biology can stem from inadequate concepts.
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

Diabetes 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.
ULTRASTRUCTURAL EVIDENCE THAT APOPTOSIS IS THE MECHANISM BY WHICH HUMAN AMYLIN EVOKES DEATH IN RINm5F PANCREATIC ISLET β‐CELLS
Authors: Saafi Etuate L. , Konarkowska Barbara , Zhang Shaoping , Kistler Joerg , Cooper Garth J. S.
Published: September 2002

A view is emerging that human amylin (HA) kills pancreatic islet β‐cells by apoptosis. This study strengthens this view by documenting time‐dependent morphological and ultrastructural changes in 10μm HA‐treated cultured RINm5F islet β‐cells. Membrane blebbing and microvilli loss were the earliest detectable apoptosis‐related phenomena, already evident 1h after HA exposure. Following 6–12h of HA‐treatment, chromatin margination became evident, consistent with detecting DNA laddering about the same time. Nuclear shrinkage, nuclear membrane convolution and prominent cytoplasmic vacuolization were clearly recognized at 22h post‐treatment. Together, these cellular changes constitute a strong case for HA‐induced apoptosis, and further demonstrates that electron microscopy is a more sensitive tool for early apoptosis detection in cultured cells than classical biochemical assays like visualizing DNA laddering. The ultrastructural changes reported here contribute further evidence to be included in the ongoing dissection of molecular mechanisms underlying HA‐induced apoptosis, as may occur in type‐2 diabetes mellitus.
DIFFERENTIATION POTENTIAL OF INTESTINAL MESENCHYME AND ITS INTERACTION WITH EPITHELIAL CELLS: A STUDY USING β‐GALACTOSIDASE‐EXPRESSING FIBROBLAST LINES
Authors: Subramanian V. , Sneddon S. F. , Martin L. , Evans G. S.
Published: September 2002

Rat intestinal fibroblast lines (F1:G9 and A1:F1) differing in their potential to support intestinal mucosal development were marked with reporter genes to investigate their differentiation potential. The fibroblasts were transfected with plasmids expressing either β‐galactosidase (with or without a nuclear localisation signal) or green fluorescent protein (GFP). Transfection using Tfx50 or Fugene™ was more efficient than electroporation. The expression of β‐galactosidase was more stable and stronger than GFP. Cells were optimally labelled using the plasmid pL27B‐GAL, and sub‐clones with a strong and uniform nuclear expression of β‐galactosidase were isolated. These clones expressed β‐galactosidase even after prolonged passage in the absence of selection. The β‐galactosidase tagged lines (F1:G9galand A1:F1gal) retained the morphological characteristics, viability and differentiation properties of the parental non‐transfected lines. In co‐culture with a colorectal tumour cell line Caco‐2, the F1:G9galand A1:F1galcells differed in their morphological organisation but this did not change their expression of smooth muscle α‐actin.
SPECIFIC INVASION OF TRANSFORMED CELLS BY ESCHERICHIA COLI A2 STRAIN
Authors: Efremova Tatiana , Ender Natalia , Brudnaja Margarita , Komissarchik Yan , Khaitlina Sofia
Published: September 2002

Bacteria of the spontaneously isolated non‐pathogenic strain Escherichia coli A2 producing actin‐specific protease ECP 32 (Usmanova and Khaitlina, 1989) were shown to be taken up by transformed cells, whereas finite and immortal cell lines were resistant to the infection.
UPREGULATION OF CYSTIC FIBROSIS TRANSMEMBRANE CONDUCTANCE REGULATOR EXPRESSION BY OESTROGEN AND BAK FOONG PILL IN MOUSE UTERI
Authors: Rowlands D. K. , Tsang L. L. , Cui Y. G. , Chung Y. W. , Chan L. N. , Liu C. Q. , James Tony , Chan H. C.
Published: September 2002

Although cystic fibrosis transmembrane conductance regulator (CFTR) has been shown to be expressed in the female reproductive tract, its functional role in the uterus is not fully understood. The present study investigated a possible physiological role of CFTR by comparing the effects of 17β‐oestradiol and Bak Foong Pill (BFP), an over‐the‐counter Chinese medicine used for centuries for the treatment of various gynaecological disorders, on uterus size and the expression of CFTR in the uterus of ovariectomised mice using RT‐PCR. Treatment of ovariectomised mice with 17β‐oestradiol (0.2mg/kg, p.o.) for 12 days caused a significnat increase in uterine wet weight compared to vehicle. However, treatment with BFP (3g/kg, p.o.) for the same period failed to increase uterine wet weight, indicating a lack of direct oestrogen‐like activity of BFP. Analysis of CFTR mRNA expression in the harvested uteri using RT‐PCR showed that both 17β‐oestradiol and BFP induced an increase in CFTR mRNA expression in mouse uteri compared to levels observed in vehicle‐treated animals. These results suggest that CFTR can be upregulated by oestrogen and BFP, however, the effect exerted by BFP does not seem to be mediated by direct oestrogen‐like activity. Regulation of CFTR expression by both oestrogen and gynaecological medication BFP indicates an important role of CFTR in reproductive functions.
QUANTIFICATION OF APOPTOTIC DNA FRAGMENTATION IN A TRANSFORMED UTERINE EPITHELIAL CELL LINE, HRE‐H9, USING CAPILLARY ELECTROPHORESIS WITH LASER‐INDUCED FLUORESCENCE DETECTOR (CE‐LIF)
Authors: Fiscus Ronald R. , Leung Catherine P. C. , Yuen Jessie P. S. , Chan H. C.
Published: September 2002

Apoptotic cell death of uterine epithelial cells is thought to play an important role in the onset of menstruation and the successful implantation of an embryo during early pregnancy. Abnormal apoptosis in these cells can result in dysmenorrhoea and infertility. In addition, decreased rate of epithelial apoptosis likely contributes to endometriosis. A key step in the onset of apoptosis in these cells is cleavage of the genomic DNA between nucleosomes, resulting in polynucleosomal‐sized fragments of DNA. The conventional technique for assessing apoptotic DNA fragmentation uses agarose (slab) gel electrophoresis (i.e. DNA laddering). However, recent technological advances in the use of capillary electrophoresis (CE), particularly the introduction of the laser‐induced fluorescence detector (LIF), has made it possible to perform DNA laddering with improved automation and much greater sensitivity. In the present study, we have further developed the CE‐LIF technique by using a DNA standard curve to quantify accurately the amount of DNA in the apoptotic DNA fragments and have applied this new quantitative technique to study apoptosis in a transformed uterine epithelial cell line, the HRE‐H9 cells. Apoptosis was induced in the HRE‐H9 cells by serum deprivation for 5, 7 and 24h, resulting in increased DNA fragmentation of 2.2‐, 3.1‐ and 6.2‐fold, respectively, above the 0h or plus‐serum controls. This ultrasensitive CE‐LIF technique provides a novel method for accurately measuring the actions of pro‐ or anti‐apoptotic agents or conditions on uterine epithelial cell lines.