bluuebunny/crossref_metadata_2025_split huggingface dataset:
Early endocytotic steps in elicited macrophages: omega‐shaped plasma membrane vesicles at their cell surface.
Authors: Kiss Anna L. , Kittel Agnes 
Published: September 2002

AbstractFluid‐phase and receptor‐mediated endocytosis were studied in Freund's adjuvant elicited macrophages. These cells were found to bind and internalize significantly larger amounts of peroxidase‐antiperoxidase (PAP) immune complex than resident macrophages. Similarly the rate of the fluid‐phase uptake was higher in elicited cells. When studying the early steps of endocytotic processes, omega‐shaped plasma membrane pits (d∼90 nm) were found at the macrophage cell surface. Although occurring occasionally in resident cells, their number was highly increased after elicitation in 30% of the macrophage cell population. The different morphology of these cells coincided with a lower endocytotic activity and a very strong ecto Ca2+‐ATPase reaction. The present findings indicate that the elicited macrophage population is heterogenous and consists of different subclasses.
Studies on the permeability of the blood‐testis barrier in stainless steel‐administered mice
Authors: Pereira M. L. 
Published: September 2002

AbstractPrevious trials performed in our laboratory have demonstrated that stainless steel corrosion products induced morphological changes in mice seminiferous cells. In this study the functional nature of the blood‐testis barrier was investigated, in view of the extesive use of this metallic alloy in orthopaedic surgery. The uptake of horseradish peroxidase by the seminiferous tubules was used as a tracer method being exposed in vitro for different periods of time and observed at the ultrastructural level. Both boundary cells as well as Sertoli cells of experimental group absorbed the tracer, as manifested by vesicles and vacuoles filled with the reaction product, evidencing its role within the testis. Germ cells were also able in the uptake of this macromolecule. However, the tracer did not spread into the junctional complexes between neighboring Sertoli cells, at any interval of time used in this study, demonstrating the functional integrity of this barrier.
HUMAN CHROMOSOME Y AND SRY
Authors: SHAH V. C. , SMART VAISHALI 
Published: September 2002

AbstractThe precise location of the SRY gene on the human Y chromosome has been revealed through studies of sex reversal cases involving deletion, cross‐linking and mutations of the SRY gene. Its DNA sequence and mechanism of action are being understood. Similarity of SRY with Sry of mice and its interaction with other genes in male sex determination are discussed.
STRUCTURE—FUNCTION RELATIONSHIPS OF NA+/K+‐PUMPS EXPRESSED INXENOPUSOOCYTES
Authors: SCHWARZ WOLFGANG , VASILETS LARISA A. 
Published: September 2002

AbstractDuring the last years we have examined structure—function relationships in the Na+/K+‐ATPase with respect to interactions of the external cations with the pump molecule. We have analysed in voltage‐clamp experiments the influence of extracellular Na+and K+on the current generated by Na+/K+‐pumps expressed inXenopusoocytes. Our results demonstrated that external Na+and K+have to pass an access channel in the electrical field of the membrane to reach their binding sites. This external access, therefore, is voltage‐dependent and is affected by lysine residues within the cytoplasmic N‐terminus, by glutamic acid residues in intramembraneous domains, the ouabain sensitivity and phosphorylation by protein kinases.
EFFECTS OF BETA MERCAPTOETHANOL ON THE PROLIFERATION AND DIFFERENTIATION OF HUMAN OSTEOPROGENITOR CELLS
Authors: INUI KENTARO , OREFFO RICHARD O.C , TRIFFITT JAMES T. 
Published: September 2002

AbstractAntioxidants are known to influence metabolism and promote cell survival in a number of cell culture systems. However, their effects on the modulation of bone cell differentiationin vitroare not clearly defined. In the present studies we have investigated the effects of β‐mercaptoethanol (βME) and ascorbate alone and in combination on human osteoprogenitors derived from bone marrow fibroblasts. In primary marrow cultures, βME stimulated colony formation (2‐fold), alkaline phosphatase activity (3.5‐fold) and, increased DNA synthesis (8‐fold) after 21 days. Cell proliferation was increased significantly by βME during the first 4 days of a 10‐day culture period, indicating stimulation of marrow osteoprogenitor proliferation. Ascorbate did not significantly augment the effects of βME in primary cultures or long‐term cultures of passaged bone marrow fibroblasts. These findings indicate a potential beneficial role for βME addition for the optimal maintenance of colony formation, cell proliferation and differentiation of marrow osteoprogenitor cells in primary human bone marrow fibroblast cultures.
PROLIFERATION AND COLLAGEN SYNTHESIS OF HUMAN ANTERIOR CRUCIATE LIGAMENT CELLS IN VITRO: EFFECTS OF ASCORBATE‐2‐PHOSPHATE, DEXAMETHASONE AND OXYGEN TENSION
Authors: Fermor B. , Urban J. , Murray D. , Pocock A. , Lim E. , Francis M. , Gage J. 
Published: September 2002

ABSTRACTClinical and experimental studies demonstrate that injured anterior cruciate ligaments (ACL) do not usually heal and that autografts used to repair the ACL rapidly weaken in the early period and take a long time to regain strength. The aim of this study was to develop an in vitro culture system in which environmental and biochemical factors influencing the proliferation and matrix synthesis of cells derived from human anterior cruciate ligaments can be studied.Primary cultures of human ACL cells were obtained by outgrowth from explants of normal ACL obtained at knee replacement for osteoarthritis in Dulbecco's minimum essential medium (DMEM). The effects of the additives 100μm l‐ascorbic acid‐2‐phosphate (Asc‐2‐P) and 10nmdexamethasone (dex) on proliferation and collagen synthesis were assessed after 4, 8 and 12 days in culture. Ligament cells were grown at 0, 5, 10 and 21% p O2in the presence of 100μmasc‐2‐P and 10nmdex. DNA content was assessed using the Hoechst dye method and collagen synthesis by the incorporation of 5mCi/ml [3H]proline after 3, 6 and 12 days in culture.At 21% p O2, the presence of asc‐2‐P and dex induced significantly greater (P< 0.01, ANOVA) cell proliferation than with either additives alone. Greatest percentage collagen to total protein synthesis was observed when cells were grown in the presence of asc‐2‐P only. Least proliferation and percentage collagen to total protein synthesis was seen when both additives were omitted. Greatest cell proliferation was seen when cells were grown in 10% p O2and 5% p O2was associated with increased collagen synthesis.These results suggest that it is possible to study the effects of environmental and biochemical factors on human ACL healing in vitro. Our data suggest oxygen can influence certain biosynthetic activities of ACL cells. Low oxygen tensions lead to an increase in collagen production by ACL cells. However early responses to injury require extensive cell proliferation which may be activated at higher p O2. Variation of p O2in ligaments during healing may therefore be an important modulator of successful repair.
GENDER‐RELATED DIFFERENCES IN ADHESION, GROWTH AND DIFFERENTIATION OF VASCULAR SMOOTH MUSCLE CELLS ARE ENHANCED IN SERUM‐DEPRIVED CULTURES
Authors: Bačáková L. , Mareš V. , Lisá V. 
Published: September 2002

AbstractIn 1‐day cultures with 10% serum, the number of rat aortic smooth muscle cells (VSMC) adhering to the growth support was similar in cells from both sexes, whereas in 1% serum, the number of VSMC from male donors was lower. In 10% serum medium, the doubling time was significantly shorter and the number of [3H]thymidine‐labelled nuclei was higher in cells of high passage from male rats. In serum‐free medium, these differences increased and were also seen in cells of low passage number. Morphologically, the cells in male‐derived cultures at higher passage number were mainly spindle‐shaped, formed well‐developed ‘hills and valleys’ and possessed longitudinally oriented bundles of α‐actin‐containing microfilaments. Most cells from female rats were flat, polygonal, the multilayered ‘hills’ were less prominent, with α‐actin microfilaments forming a mesh‐like network.
MOTOGENIC AND BIOSYNTHETIC RESPONSE OF ADULT SKIN FIBROBLASTS TO TGF‐β ISOFORMS (−1, −2 AND −3) DETERMINED BY ‘TISSUE RESPONSE UNIT’: ROLE OF CELL DENSITY AND SUBSTRATUM
Authors: Ellis I.R , Banyard J. , Schor S.L 
Published: September 2002

AbstractWe have recently demonstrated that the three principal mammalian isoforms of transforming growth factor β (TGF‐β) exert distinct effects upon: (1) the migration of confluent adult fibroblasts into 3D gels of native type I collagen fibres (i.e. TGF‐β−1 and −2 had no apparent motogenic activity, whilst TGF‐β−3 induced a dose‐dependent stimulation of cell migration); and (2) the synthesis of hyaluronan (HA) by these cells is also affected by the TGF‐β isoforms in a manner which parallels their effect on cell migration. The objective of the present study is to elucidate the manner in which this differential activity of the TGF‐β−1, −2 and −3 may be modulated by experimental parameters. Data presented in this communication indicate that cytokine bioactivity is determined by a combination of cell density and the nature of the macromolecular substratum. Thus, we now report that all three TGF‐β isoforms inhibit the migration of subconfluent cells in the collagen gel assay. Our data confirm that the migration of confluent cells is stimulated by TGF‐β−3 and further indicate that this motogenic activity is completely abrogated by either TGF‐β−1 or −2 when these are co‐incubated with TGF‐β−3. In contrast to these results obtained using a native type I collagen substratum, all three isoforms stimulated adult fibroblast migration in the transmembrane assay (in which cells are adherent to a 2‐D porous polycarbonate substratum). The precise effect of TGF‐β isoforms on HA synthesis was also affected by cell density and the nature of the substratum in a manner which paralleled their diverse effects on cell migration (i.e. stimulation, inhibition or no effect). Streptomyces hyaluronidase completely neutralized the TGF‐β−3‐induced stimulation of confluent fibroblast migration, thus suggesting a mechanistic link between the cytokine‐induced cell migration and HA synthesis under these conditions. Taken together, these data indicate that: (1) the bioactivity of TGF‐β−1, −2 and −3 are determined by cell density, the macromolecular substratum and the presence of other cytokines; and (2) it is therefore necessary to define cytokine bioactivity within the context of a larger ‘tissue response unit’ which more fully defines the activity state of the target cell and its microenvironment.
REACTIVE OXYGEN SPECIES INDUCE APOPTOSIS OF SYNOVIOCYTES IN VITRO. α‐TOCOPHEROL PROVIDES NO PROTECTION
Authors: Galleron S. , Borderie D. , Ponteziere Ch , Lemarechal H. , Jambou M. , Roch‐Arveiller M. , Ekindjian O.G , Cals M.J 
Published: September 2002

AbstractReactive oxygen species (ROS) are released during the inflammation of the synovial membrane associated with cartilage degradation in osteoarthritis. In this work, we exposed synoviocytes to superoxide anions at concentrations that may cause either apoptosis or necrosis. We studied membrane organization, dehydrogenase mitochondrial activity and nuclear morphology and integrity, to determine the nature of the death process initiated by superoxide anions and tried to counteract ROS effects with α‐tocopherol. We found that oxidative stress caused synoviocytes to undergo a process of cell death of an apoptotic nature rather than necrotic. Mitochondrial injury occurred at an early stage, and the FITC‐annexin‐V‐positive/propidium iodide‐positive cells occurred later than the metabolic changes. DNA strand breaks were evident at 8h and nuclear condensation at 24h. No LDH activity was detected in culture supernatants. In our experimental conditions, α‐tocopherol had little effect on stress damage; the antioxidant properties of this molecule did not affect the apoptosis caused by superoxide anions.
A GLYCOPROTEIN ISOLATED FROM THE SPONGE, PACHYMATISMA JOHNSTONII, HAS ANTI‐LEISHMANIAL ACTIVITY
Authors: Le Pape Patrice , Zidane Mohamed , Abdala Hiam , Moré Marie‐Thérèse 
Published: September 2002

AbstractA high anti‐leishmanial activity was observed in an aqueous extract from the marine spongePachymatisma johnstonii, Bowerbank 1842 (Demospongiae, Geodiidae). Pachymatismin, a glycoprotein, was purified and shown to be a cytotoxic agent, which acts on promastigote and clinical‐like amastigote stages with IC50about 1μg protein/ml and induces changes in the cell shape, phospholipase A2activity and invasion capacity of the parasite. We believe pachymatismin is the first reported substance from a marine organism with anti‐leishmanial activity.
CD56 DIRECTLY INTERACTS IN THE PROCESS OF NCAM‐POSITIVE TARGET CELL‐KILLING BY NK CELLS
Authors: Takasaki Satoko , Hayashida Kazuhiro , Morita Chie , Ishibashi Hiromi , Niho Yoshiyuki 
Published: September 2002

AbstractThe role of CD56 in the process of target cell killing by NK cells has been investigated. Addition of NK cells to HuH28 cells, a CD56‐expressing cell line, led to inhibition of the growth of the target cells, which exhibited morphological features of apoptosis. These changes were prevented by the addition of a polyclonal anti‐NCAM to the cultures. Since neither Fas antigen expression nor apoptotic changes were induced by addition to a mixed culture supernatant of NK and target cells, both the Fas‐Fas ligand system and soluble factors do not seem to participate in apoptosis in these circumstances. Increased secretion of interferon‐γ and tumour necrosis factor‐α by NK cells must therefore have been suppressed by the presence of the polyclonal antibody. These results lead us to conclude that CD56, through homophilic binding, plays an important role in the process of target cell killing by an apoptosis mechanism.
CYTOKINESIS IN CELLS UNDERGOING MITOSIS WITHOUT GENOME REPLICATION
Authors: Wise Dwayne A. 
Published: September 2002

AbstractChinese hamster ovary cells can be forced to enter mitosis without prior DNA replication by treatment with hydroxyurea and caffeine. Cells treated in this way assemble a spindle that functions normally except that it does not accomplish anaphase spindle elongation (anaphase B). The chromatin detaches from the unreplicated kinetochores, which fragment, but establish microtubule attachments and migrate to the metaphase plate. Partitioning of the kinetochore fragments ensues on the normal schedule. Typical midbodies and cleavage furrows are established and daughter cells of equal size are produced. These results imply that intact chromosomes are not necessary for correct cleavage furrow placement but that kinetochores might be. Further, it is clear that cleavage furrow placement does not depend on anaphase spindle elongation.
UNILATERAL AND WANDERING FURROWS DURING MITOSIS IN VERTEBRATES: IMPLICATIONS FOR THE MECHANISM OF CYTOKINESIS
Authors: Savoian M.S , Khodjakov A. , Rieder C.L 
Published: September 2002

AbstractVertebrate somatic cells sometimes form unilateral furrows during cytokinesis that ingress from only one edge of the cell. In some cases after a cell initiates a normal symmetrical circumferential furrow, one of its edges stops furrowing and regresses while the furrow associated with the opposing edge continues across the cell. In cells containing two independent spindles unilateral furrows are sometimes formed that do not follow a linear path but instead sharply change their direction and wander for >40μm through the cell. These observations reveal that the ‘contractile ring’ normally seen during cytokinesis is composed of multiple independent ‘furrowing units’ that are normally coordinated to form a symmetrical furrow around the cell, and that once formed this so‐called contractile band does not function as a ‘purse string’ as commonly envisioned. Individual furrowing units can work independently of one another, and cytokinesis in vertebrates can be consummated by the formation of a single functional furrowing unit in a localized region of the cell cortex that is then propagated across the cell. How this propagation occurs remains an important question for the future.
HISTOCHEMICAL CHARACTERIZATION OF CELL DEATH IN HONEYBEE LARVAE MIDGUT AFTER TREATMENT WITH PAENIBACILLUS LARVAE, AMITRAZ AND OXYTETRACYCLINE
Authors: Gregorc Aleš , Bowen Ivor D. 
Published: September 2002

AbstractA number of techniques were employed to assess cell death induced in honeybee larvae midgut afterper os inoculation of bacterium Paenibacillus larvae var. larvae, the causative agent of American foulbrood disease, and separately with acaricide Amitraz and antibiotic Oxytetracycline. In honeybee larvae exposed to Amitraz, which demonstrates both necrosis and apoptosis, cell death was found in 82% of midgut columnar and in 50% of regenerative epithelial cells, 24h after treatment. Cell death reduced to 36% in the epithelial cells, 48h after treatment. In Oxytetracycline‐treated larvae, cell death was identified in 40% of midgut epithelial cells, 24h after inoculation and increased to 55% over the next 24h. In Paenibacillus ‐infected larvae, all midgut epithelial cells died. Using ApopTag (Oncor) to label the multiple DNA ends generated by DNA fragmentation showed programmed cell death in 49% of columnar midgut cells 24h after Amitraz application. Cell death was reduced to 9% over the next 24h. Our data indicate that cell death could be identified and quantified in situ, using TUNEL techniques. This study also shows that the acaricide Amitraz is a trigger for programmed cell death in the midgut epithelial cells of honeybee larvae, unlike Paenibacillus which induces necrosis only. The data show that immunohistochemical methods are useful for studying in situ tissue pathology, and indicate possibilities for monitoring the effects of infective and chemical environmental stressors on cell death in honeybee larvae tissue.
PACKING OF MYOSIN MOLECULES IN MUSCLE THICK FILAMENTS
Authors: Miroshnichenko N. S. , Balanuk I. V. , Nozdrenko D. N. 
Published: September 2002

AbstractThe backbone of the myosin filament is an aggregate of α‐helical coiled coil myosin rods. Its surface forms a three‐stranded helix composed of myosin heads. Currently there is no adequate model to describe the organization of the myosin filament. It is proposed here that, in cross‐section the light meromyosin (LMM) of 18 myosin molecules form an outer tube, with nine S2 forming the interior core. At the surface of the thick filament, myosin heads are arranged in three rows, giving the filament a periodicity of 14.3nm per three myosin molecules. Two of these molecules are organized at an angle of 120 degrees to each other on the same level, while the third is shifted 7.2nm along the filament axis. This packing gives a striation pattern of 7.2nm by electron microscopy. An alternative model is also possible, in which the heads of the myosin molecules are uniformly spaced at an interval of 14.3nm along the filament axis. The packing of individual molecules within the myosin filament is based on a regular pattern of charge on the 28 amino‐acid repeat in the rod domain.
EFFECT OF ABSCISIC ACID AND COLD ACCLIMATION ON THE CYTOSKELETAL AND PHOSPHORYLATED PROTEINS IN DIFFERENT CULTIVARS OFTRITICUM AESTIVUML
Authors: Olinevich Olga V. , Khokhlova Ludmila P. , Raudaskoski Marjatta 
Published: September 2002

AbstractIn winter wheat, the tubulin and 60kDa‐phosphorylated proteins/actin ratio is considerably higher in the roots than in the leaves. Differences in the content of the main cytoskeletal proteins were also found in the leaves of the different cultivars. It is suggested that the lower amount of the tubulin and 60kDa‐phosphorylated proteins and higher content of actin determine the greater tubulin cytoskeletal stability in the leaves and their higher frost resistance, as compared with the roots. Also, it is possible that the higher content of the tubulin and 60kDa‐phosphorylated proteins defines the lower microtubule (MT) stability in the leaves of the low frost resistant cultivar than in the leaves of the more frost resistant ones. In the roots and leaves of the low frost resistant cultivar, the low stability of the numerous tubulin structures is apparently one reason for the abscisic acid (ABA)‐induced reduction of the cytoskeletal and 60kDa‐phosphorylated proteins in the cells. The cold acclimation compensated the ABA effect in the roots of the very frost resistant cultivar in the most extent. This suggests the existence of the different pathways in the increased plant cell frost resistance through the action of ABA and low temperature.
DIFFERENTIAL RESPONSIVENESS OF PROSTATIC ACID PHOSPHATASE AND PROSTATE‐SPECIFIC ANTIGEN mRNA TO ANDROGEN IN PROSTATE CANCER CELLS
Authors: Lin Ming‐Fong , Lee Ming‐Shyue , Garcia‐Arenas Renee , Lin Fen‐Fen 
Published: September 2002

AbstractAndrogens regulate the expression of both human prostatic acid phosphatase (PAcP) and prostate‐specific antigen (PSA), two major prostate epithelium‐specific differentiation antigens. Due to the important role of these two enzymes as prostate epithelium differentiation markers, we investigated their regulation of expression at the mRNA level in LNCaP human prostate carcinoma cells. Interestingly, phenol red, a pH indicator in the culture medium, promoted cell growth. To eliminate this non‐specific effect, a phenol red‐free, steroid‐reduced medium was utilized. When high‐density cells were grown in that medium, 5α‐dihydrotestosterone (DHT) suppressed PAcP but stimulated PSA. However, tumor promoter phorbol ester 12‐ o ‐tetradecanoyl phorbol‐13‐acetate (TPA) functioned as a potent inhibitor of both PAcP and PSA expression. Prolonged treatment with DHT as well as TPA resulted in a similar down‐regulation of protein kinase C and cellular PAcP activities. Thus, the levels of PAcP and PSA mRNA are differentially regulated by androgens in LNCaP cells.
HEAT SHOCK‐INDUCED ACTIN POLYMERIZATION, SAPK/JNK ACTIVATION, AND HEAT‐SHOCK PROTEIN EXPRESSION ARE MEDIATED BY GENISTEIN‐SENSITIVE TYROSINE KINASE(S) IN K562 CELLS
Authors: Han Song Iy , Ha Kwon‐Soo , Kang Kwang Il , Kim Han Do , Kang Ho Sung 
Published: September 2002

AbstractUpon exposure to elevated growth temperatures, mammalian cells exhibit a variety of cellular responses, such as the expression of heat‐shock proteins (HSPs) and the activation of stress‐activated protein kinase/c‐Jun N‐terminal kinase (SAPK/JNK). In this study, we show that heat shock transiently induces morphological change (cell elongation) and polymerization of actin, but not of microtubules, in human erythroleukaemic K562 cells. Pretreatment with actinomycin D or cycloheximide did not prevent the heat shock‐induced cell elongation and actin reorganization, indicating that gene transcription and protein synthesis are not required for this phenomenon. The alterations in cell morphology and actin structure in response to heat shock were specifically inhibited by genistein, a tyrosine kinase inhibitor, but not by other kinase inhibitors, including tyrosine kinase inhibitors (herbimycin and tyrphostin) and protein kinase C inhibitors (staurosporine and H7). The activities of genistein‐sensitive tyrosine kinase (GTK) and c‐Src were enhanced by heat‐shock treatment. In addition, a 75kDa protein was highly phosphorylated in its tyrosine residues(s) by heat shock, and the phosphorylation was prevented by genistein pretreatment. Genistein also inhibited the heat‐shock‐induced SAPK/JNK activation and HSP expression. In contrast, while colchicine, a microtubule‐disrupting agent, was able to induce actin polymerization and SAPK/JNK activation, these events were not inhibited by genistein. These results suggest that the heat‐shock‐induced actin polymerization, HSP expression, and SAPK/JNK activation may be mediated by the specific signal pathway involving GTK(s), while colchicine‐induced actin polymerization and SAPK/JNK activation is regulated in a different manner.