bluuebunny/crossref_metadata_2025_split huggingface dataset:
Short‐latency ionic effects of nerve growth factor deprivation and readministration on ganglionic cells
Authors: Varon Silvio , Skaper Stephen D. 
Published: May 2005

AbstractNerve growth factor (NGF) is likely to exert its trophic action on dorsal root ganglion (DRG) and on sympathetic ganglion neurons by controlling a crucial function of these cells. This function would in turn regulate other cellular machineries and, ultimately, lead to the traditional NGF consequences, such as survival and neuritic growth. A corollary of this view is that the key to NGF action must lie in short‐latency events, occurring within minutes of NGF administration. Chick embryo DRG dissociates have proved to be an effective experimental system to investigate short‐latency responses to NGF, in that (1) measurable functional deficits develop over 6 h of NGF deprivation in vitro and (2) delayed presentation of NGF promptly and fully restores the defective function. The first deficit observed in this experimental system, a decline in RNA‐labeling capability, led to the recognition that NGF controls the transport of selected exogenous substrates, all of which are Na+‐coupled and depend on an Na+ gradient across the neuronal membrane. Subsequent work showed that NGF controlled such transport systems by actually regulating the neuronal ability to control intracellular Na+. Under NGF deprivation, the DRG cells accumulate Na+ to levels that reflect, and presumably equate, the extracellular Na+ concentrations. Conversely, on delayed NGF administration, the accumulated Na+ is actively extruded to an extent and at a speed that depends on the NGF concentration. The Na+ response is elicited by both Beta and 7S NGF, but not by other proteins tested. All ganglionic systems that display a requirement for exogenous NGF in culture have also displayed the Na+ response to NGF. The Na+ response is grossly paralleled by a K+ response. DRG dissociates, in which intracellular K+ has been pre‐equilibrated with extracellular 86Rb+, lose their 86Rb+ over 6 h of NGF deprivation and restore it on delayed NGF administration. The regulation by NGF of mechanisms controlling intracellular Na+ and K+ levels in their target neurons is likely to occupy an early and fundamentl place in the sequence of events underlying the mode of action of this factor.
Visualization of thrombin receptors on mouse embryo fibroblasts using fluorescein‐amine conjugated human α‐thrombin
Authors: Carney Darrell H. 
Published: May 2005

AbstractThe localization of thrombin receptors on mouse embryo (ME) cells has been examined by direct fluorescence microscopy using a fluorescein aminelabeled thrombin. Two fluorescein amines, 4‐(N‐6‐aminoethyl thioureal)‐fluorescein and 4‐(N‐6‐aminohexyl thioureal)‐fluorescein, were synthesized and attached to the carbohydrate moiety of highly purified human α‐thrombin by periodate oxidation of the carbohydrate and selective reduction of the Schiff's base using sodium cyanoborohydride. Preparations of fluorescent thrombin with from 1 to 4 fluoresceins per molecule of thrombin retained their ability to proteolytically cleave fibrinogin to form fibrin clots, to bind to thrombin receptors on ME cells, and to initiate cell division. After incubating mitogenic concentrations of the fluorescein amine labeled thrombin with ME cells at 4°C, a diffuse fluorescent pattern was observed over the surface of the ME cells. This diffuse pattern was specific: it was not observed on cells from parallel cultures incubated with fluorescent thrombin plus a 20‐fold excess of unlabeled thrombin. Thus, thrombin receptors appear to be distributed randomly over the surface of ME cells prior to interaction with thrombin. Increasing the temperature to 37°C following binding at 4° C resulted in a rapid dissociation of the fluorescent pattern from the cells leaving only the autofluorescent vesicles. This result may reflect the unique ability of thrombin to proteolytically cleave its own receptor.
Self‐renewal of factor‐dependent hemopoietic progenitor cell‐lines derived from long‐term bone marrow cultures demonstrates significant mouse strain genotypic variation
Authors: Greenberger Joel S. 
Published: May 2005

AbstractLong‐term bone marrow cultures established from C57Ks/J mice have been shown to spontaneously release endogenous ecotropic RNA type‐C virus (retrovirus). C57Ks/J marrow cultures produced granulocyte‐macrophage progenitor cells (GM‐CFUc) and immature and mature granulocytes for over 45 weeks. In contrast, NIH Swiss mouse marrow cultures failed to release detectable ecotropic virus and generated GM‐CFUc and granulocytes for 25–35 weeks and established WEHI‐3 conditioned medium (CM) dependent cell lines in vitro and did not establish permanent cell lines. To determine whether viral and/or cellular genes regulated the longevity of C57Ks/J marrow cultures, groups of cultures were established from the marrow of (NIH‐Swiss × C57Ks/J) F1 hybrid, F2 hybrid, and (NIH Swiss × C57Ks/J) X NIH Swiss backcross generations. Release of endogenous ecotropic virus was measured weekly in each culture as was the duration of production of immature granulocytic cells and GM‐CFUc over a 58‐week period. The results demonstrated a complex pattern of inheritance of longevity of long‐term in vitro hemopoiesis. Increased longevity did not absolutely correlate with detectable replication of the C57Ks/J N‐tropic virus.
The role of cells and their products in the regulation of in vitro stem cell proliferation and granulocyte development
Authors: Dexter T. M. , Spooncer E. , Toksoz D. , Lajtha L. G. 
Published: May 2005

AbstractIn long‐term marrow cultures haemopoiesis can be maintained in vitro for up to 6 months. Critical analysis of the cell populations produced has shown that the stem cells and their committed progeny have characteristics in common with the corresponding cell types in vivo. The maintenance of haemopoiesis in vitro is associated with the development of an appropriate inductive environment provided by bone marrow derived adherent cells. Analysis of the interactions between environmental and haemopoietic cells has been facilitated by the development of in vitro systems reproducing the naturally occurring genetic environmental defects and other systems where the development of a competent inductive environment shows a dependency upon corticosteroid hormones. Investigations have shown that stem cell proliferation may be controlled by production of opposing activities, one stimulatory for DNA synthesis, the other inhibitory. A model is proposed whereby modulation in the production of these factors is determined by the physical presence of stem cells in a proposed cellular milieu, within the adherent layer. The adherent layer, apart from acting at the level of stem cell proliferation, can also modify the response of differentiating cells (eg, GM‐CFC) to exogenous stimulatory activities. Addition of GM‐CSF or of CSF‐antiserum has no effect on haemopoiesis in long‐term cultures.
Oxytocin action: Lack of correlation between receptor number and tissue responsiveness
Authors: Goren H. J. , Geonzon R. M. , Hollenberg M. D. , Lederis K. , Morgan D. O. 
Published: May 2005

AbstractBrattleboro rats exhibit diabetes insipidus (DI) because of a genetic autosomal recessive defect in the synthesis of vasopressin; oxytocin is synthesized normally. Preliminary work suggests that elevated circulating oxytocin levels may compensate for the absence of vasopressin. To evaluate the consequences of presumed elevations of oxytocin levels, oxytocin binding and tissue responsiveness have been measured in the uterus and epididymal fat cells of homozygous‐DI (HoDI) and heterozygous‐DI (HeDI) animals and Sprague‐Dawley and Long‐Evans controls. Surprisingly, whereas membranes from HoDI rat uteri exhibited an 85% reduction in oxytocin binding, the biological response (contraction) to oxytocin was indistinguishable from the uteri of HeDI or Sprague‐Dawley animals. The uterine response to carbachol was also normal in HoDI rats. In contrast, in adipocytes from HoDI animals, the biological response to oxytocin (glucose oxidation) was abolished, whereas the binding of oxytocin was normal; insulin‐stimulated glucose oxidation was, however, normal. These results indicate that receptor binding, while critical to hormone action, is not the sole determining factor. With oxytocin action, postreceptor mechanisms are most important in determining oxytocin responsiveness.
Studies on the biogenesis of an enzymatically active complex III of the respiratory chain from yeast mitochondria
Authors: Beattie Diana S. , Battie Cynthia A. , Weiss Robert A. 
Published: May 2005

AbstractComplex III isolated from yeast mitochondria catalyzed an antimycin A and Diuron‐sensitive coenzyme QH2‐cytochrome c reductase activity with a turnover number of 15.7 sec−1 and contained 10 nmoles of cytochrome b and 4.6 nmoles of cytochrome c1 per mg of protein. Electrophoresis in sodium dodecyl sulfate acrylamide gels resolved Complex III into 10 bands with apparent molecular weights of 50,000, 40,000, 30,000, 29,000, 24,000, 17,000, 16,000, 12,000, 8,400, and 5,800. Yeast cells were labeled under nongrowing conditions with (35S)‐methionine in the absence or presence of inhibitors of cytoplasmiċ or mitochondrial protein synthesis. Labeled Complex III was isolated by immunoprecipitation from detergent‐solubilized mitochondria using antiserum raised against the purified complex. Analysis of the immunoprecipitates by polyacrylamide gel electrophoresis revealed that a 30,000‐dalton protein, cytochrome b, as well as 16,000‐dalton protein were labeled in the presence of cycloheximide, indicating that they are products of mitochondrial protein synthesis. Immunoprecipitates from mitochondria obtained from cells labeled in the presence of chloramphenicol contained a new radioactive peak with a molecular weight of 100,000. In addition, significant decreases in the labeling of the proteins with molecular weights of 50,000, 40,000, 30,000, and 16,000 were observed. When Complex III was isolated by immunoprecipitation from intact spheroplasts after a 5‐minute pulse with (35S)‐methionine, the 100,000‐dalton protein was labeled in the immunoprecipitate whether or not chloramphenicol was present; however, after a 1‐hour chase with unlabeled methionine, decreased labeling of the 100,000‐dalton protein was observed concomitant with an increased labeling of the 50,000‐ and 40,000‐dalton proteins. These results suggest that a protein with a molecular weight of 100,000 may either be a precursor or a partially assembled form of other proteins of Complex III, most probably the two largest polypeptides.
The cell substratum modulates skeletal muscle differentiation
Authors: Elson Hannah Friedman , Ingwall Joanne S. 
Published: May 2005

AbstractDuring chick embryogenesis, massive alterations occur in the migrating cell's substratum, or extracellular matrix. The possibility that some of the components of this milieu play a regulatory role in cell differentiation was explored in a cell‐culture system derived from embryonic chick skeletal muscle tissue. In particular, the effects of collagen and the glycosaminoglycans were studied. Collagen is required for muscle cell attachment and spreading onto plastic and glass tissue‐culture dishes. A major constituent of the early embryonic extracellular space, hyaluronate (HA), while having no significant effect on collagen‐stimulated cell attachment and spreading, was found to inhibit myogenesis. The muscle‐specific M subunit of creatine kinase was preferentially inhibited. Control experiments indicated that the inhibition was specifically caused by HA and not by other glycosaminoglycans. A general metabolic inhibition of the cultures was not observed. Muscle cells could bind to HA‐coated beads at all stages of differentiation but were inhibited only when HA was added within the first 24 h of culture. Endogenous GAG in the culture is normally degraded during the first 24 h after plating as well; this may parallel the massive degradation of HA that occurs in the early embryo in vivo. These findings suggest a regulatory role for HA in modulating skeletal muscle differentiation, with degradation of an inhibitory component of the cell substratum a requirement for myogenesis.
Hormonal regulation of the adrenocortical cell
Authors: Gill Gordon N. , Hornsby Peter J. , Simonian Michael H. 
Published: May 2005

AbstractMonolayer cultures of bovine and human adrenocortical cells have been used to study regulation of growth and function. Homogeneous bovine adrenocortical cells exhibit a finite life span of ∼60 generations in culture. Full maintenance of differentiated function (steroid hormone synthesis) requires an inducer such as ACTH and antioxidizing conditions. Full induction of differentiated function occurs only when cellular hypertrophy is stimulated by growth factors such as fibroblast growth factor and serum. ACTH and other agents that increase cellular cAMP inhibit replication but do not block growth factor‐induced cellular hypertrophy. ACTH and growth factors together result in a hypertrophied, hyperfunctional cell. Replication ensues only when desensitization to the growth inhibitory effects of ACTH occurs.Cultures of the definitive and fetal zones of the human fetal adrenal cortex synthesize the steroids characteristic of the two zones in vivo. ACTH stimulates production of dehydroepiandrosterone (DHA), the major steroid product of the fetal zone, and of cortisol, the characteristic steroid product of the definitive zone. Prolonged ACTH treatment of fetal zone cultures results in a preferential increase in cortisol production so that the pattern of steroid synthesis becomes that of the definitive zone. The preferential increase in cortisol production by fetal zone cultures results from induction of 3β‐hydroxysteroid dehydrogenase, Δ4,5 isomerase activity, which is limiting in fetal zone cells. ACTH thus causes a phenotypic change in fetal zone cells to that of definitive zone cells.In both bovine and human adrenocortical cells, the principal effect of ACTH is to induce full expression of differentiated function. This occurs only under conditions where growth substances and nutrients permit full amplication.
Genetics of receptors for bioactive polypeptides: A variant of swiss/3T3 fibroblasts resistant to a cytotoxic insulin accumulates lysosome‐like vesicles
Authors: Miskimins W. Keith , Ferris Wayne R. , Shimizu Nobuyoshi 
Published: May 2005

AbstractRecently we have isolated six variants of Swiss/3T3 mouse fibroblasts that are resistant to the cytotoxic insulin‐diphtheria toxin A fragment. All of the variants proved to have greatly reduced or no insulin binding capacity, and several variants showed altered morphologies and growth characteristics. We now report on the further characterization of one of these variants, CI‐3. which displays a massive accumulation of membranous vesicles in its cytoplasm. By electron microscopy these vesicles resemble lysosomes. They also appear to fluorcsce bright orange after treatment of viable cells with acridine orange. However, the specific activity of several lysosomal enzymes is depressed in CI‐3. Additionally, there is an apparent shift in the density of vesicles containing lysosomal enzymes in this variant. These alterations may be directly related to CI‐3′s resistance to the cytotoxic insulin and have some important bearings on the mechanism of insulin action.
Tannic acid‐glutaraldehyde fixation reveals calcium ionophore‐induced changes in rabbit polymorphonuclear leukocyte membranes
Authors: Shannon W. Allen , Zellmer Daniel M. 
Published: May 2005

AbstractTAG fixation of normal and Ca2+ ionophore‐treated rabbit polymorphonuclear leukocytes (PMN) has revealed membrane components not apparent with conventional glutaraldehyde fixation. These included a 30 Å external electron‐dense coating on untreated cells. A somewhat thicker coat (40 Å) was observed in ionophore‐treated, nondegranulating PMN. In ionophore‐treated, degranulating PMN, a 65 Å cell membrane coat was observed. A similar coat was observed on the inner side of the membrane of some azurophil‐type granules, but the electron density and thickness were not so pronounced. Cytoplasmic granules were often closely apposed and often protruded outward at the plasma membrane. Extracellular lamellae, sometimes stacked apposed to the plasma membrane, possibly represent remnants of intense granule extrusion. Sequential degranulation of the respective granules was not apparent.
Antigenic and genetic parameters in the stimulation and in the lytic phases of anti‐hapten + self cytotoxic T cells and their derived clones: Role of the T helper cell
Authors: Schmitt‐Verhulst A.‐M. , Albert F. , Guimezanes A. , Buferne M. 
Published: May 2005

AbstractRequirements for stimulation of cytotoxic T cells (CTL) and for their lytic recognition have been compared in T cell lines repeatedly stimulated with trinitrobenzene sulfonate‐treated syngeneic murine spleen cells. Differences were observed between the requirements for cells to stimulate or to be lysed by the CTL, which included: (a) the expression of major histocompatibility complex (MHC = H‐2) encoded allelic products, and (b) the hapten density. Propagation of the CTL within the line required I‐A intra‐H‐2 homology between hapten‐treated stimulating cells and the line cells, whereas the lytic interaction required H‐2K region homology between hapten‐treated target cells and CTL. The hapten density requirement was analyzed for a responder (H‐2k) and a non‐responder (H‐2b) strain to low hapten density modified syngeneic cells. This property was found to be a characteristic of the lytic phase rather than of the stimulation of CTL. CTL clones could be derived by growing the line cells under conditions of limiting dilution in the presence of T cell growth factors. Such CTL clones were unable to be stimulated by their target antigens and were dependent on T cell growth factors for their propagation. These results are discussed in terms of the dependence of the development and growth of CTL on T helper cells.
Neue Untersuchungen über die Adsorption von Wasserstoff bei der Auflösung von Eisen
Authors: Cavallaro L. , Bolognesi G. P. , Felloni L. 
Published: May 2005

AbstractEs wurden die Auflösungsvorgänge von Eisen in In‐HCL untersucht und ein Zusammenhang zwischen der Menge des vom Eisen aufgenommenen Wasserstoffs und der Auflösungsgeschwindigkeit des Metalls gefunden. Es stellt sich dabei ein dynamisches Sättigungsgleichgewicht im Innern des Metalls ein. Daraus läßt sich die Bedeutung der Teil‐Reaktionen ableiten und das Eingreifen von Inhibitoren erklären.
Erörterung der Aus‐ oder Umschalttechnik bei der Potentialmessung für den kathodischen Korrosionsschutz
Authors: Schwenk Wilhelm 
Published: May 2005

AbstractBeim kathodischen Korrosionsschutz ist die Potentialmessung für die Kontrolle eines ausreichenden Schutzes notwendig. Bei der Potentialmessung einer stromdurchflossenen Elektrode wird immer ein Ohmscher Spannungsabfall miterfaßt, so daß der Meßwert zu negative erscheint. Durch eine Aus‐ bzw. Umschalttechnik kan dieser Spannungsabfall eliminiert werden. Hierbei ist es aber möglich, daß ein zu hoher Spannungsbetrag abgezogen wird, so daß der Meßwert zu positiv erscheint.Der bei der Aus‐ bzw. Umschalttechnik verursachte Fehler ist vernachlässigbar klein. Für Umschaltprozesse kann theoretisch hergeleitet werden, daß der Fehler kleiner als 50 mV ist. Für Ausschaltprozesse kann eine ähnliche Abschätzung nicht durchgeführt werden. Jedoch zeigen Versuchsergebnisse, daß auch in diesem Falle der Fehler sehr klein ist. Die Aus‐ bzw. Umschalttechnik kann für Potentialmessungen beim kathodischen Korrosionsschutz mit vernachlässigbarem Fehler angewendet werden.
Über die derzeitigen Kenntnisse vom Alterungsverhalten der glasfaserverstärkten Kunststoffe und Versuche einer mechanisch‐technologischen Deutung des Phänomens
Authors: Matting A. , Müuller D. 
Published: May 2005

AbstractKunststoffe zeigen eine ausgeprägtere Zeit‐ und Umweltabhängigkeit ihrer Eigenschaften, insbesondere der Festigkeitseigenschaften, als die meisten anderen Werkstoffe der Technik. Der zunehmende Einsatz glasfaserverstärkter Kunststoffe machte deshalb grundlegende Untersuchungen über das Langzeitverhalten not‐wendig.Der Einfluß langandauernder statischer und dynamischer Belastung sowie von Temperatur und Klimaten auf die Festig‐keitseigenschaften der glasfaserverstärkten Kunststoffe wird dargestellt und an Hand spannungsoptischer Untersuchungen der Grenzfläche zwischen Harz und Glas gedeutet.
Zur Korrosion milchwirtschaftlicher Geräte aus Kunststoffen und ihre Folgeerscheinungen
Authors: Kiermeier Friedrich 
Published: May 2005

AbstractDie wiedergegebenen Wechselbeziehungen zwischen Kunststoff und Lebensmittel wird der Theoretiker nur widerwillig unter den Begriff „Korrosion”︁ einreihen wollen. Der Verfasser möchte jedoch zu bedenken geben, daß der Lebensmittelchemiker einen wesentlich strengeren Maßstab anlegen muß. Beispielsweise macht die an sich geringfügige Porosität einer verzinnten Dose die darin aufbewahrte Kondensmilch auf Grund des Übertritts von wenigen mg Eisen als Weißungsmittel für Kaffee unbrauchbar; ebenso genügen wenige mg von Kupfer einer Rahmpumpe, daß die Butter in kurzer Zeit ranzig wird. Bei der Korrosion der Kunststoffe liegt für den Lebensmittelchemiker meines Erachtens nach die gleiche Situation vor. Das Ausmaß der Korrosion der Kunststoffe auf dem Lebensmittelsektor ist im allgemeinen zwar geringfügig, durch die ausgelösten mikrobiologischen und sinnesphysiologischen Folgeerscheinungen kann jedoch die Korrosionswirkung so potenziert werden, daß das Lebensmittel für den Verbraucher nicht mehr zumutbar wird.
Erfahrungsaustausch und Schadensfälle. Schadensfälle durch falsche Werkstoffwahl und falsche Werkstoffkombinationen
Authors: Oeteren K. A. 
Published: May 2005

AbstractDer Verfasser betont die Notwendigkeit der Wahl von Werkstoffen, die unter den vorgesehenen Korrosionsbedingungen beständig und miteinander verträglich sind. Dieser Grundsatz wird anhand von einigen Schadensfällen aus der industriellen Praxis erlätert, wo die Verwendung von Werkstoffen, Überzügen und ungeeigneten Werkstoffkombinationen zu Veränderungen des Aussehens sowie zu Kontaktkorrosion, Lochfraß und Spaltkorrosion geführt hat. Derartige nichtverträgliche Kombinationen sind z. B. Al/Cu, Zn/Cu, Stahl/Edelstahl, Al/Stahl und Cu/Stahl. Ebenso wird gezeigt, daß es notwendig ist, eine Gesamtbeschichtung und nicht nur eine Teilbeschichtung vorzusehen, da schon im Falle von unterschiedlichen Schichtdicken (z. B. Schmelztauchverzinkung neben elektrolytischer Verzinkung) unterschiedliche Lebensdauern resultieren können.
High‐temperature corrosion of NiCrAl alloy in oxygen‐chlorine mixtures
Authors: Viswanath R. P. , Rein D. , Hauffe K. 
Published: May 2005

AbstractIn order to decrease the attack of chlorine in O2Cl2N2 mixtures to NiCr alloys at high temperatures, the corrosion of a preoxidized Ni 20 Cr 4 Al alloy was investigated in N2O2 mixtures with 5 to 150 torr O2 and 20 torr Cl2 at 800°. For the generation of a protective layer of Al2O3 both the untreated and Al evaporated alloy sample was preoxidized in a H220 torr H2O atmosphere at 900° C. As was found, the catastrophic corrosion by Cl2 in a N2Cl2 gas mixture with 20 torr Cl2 could not be prevented by an Al2O3 layer. However, in the simultaneous presence of an oxygen content in the corroding gas mixture not lower than 10 torr, the attack of chlorine could be drastically decreased. The presence of 50 torr Cl2 postulates an oxygen pressure which is technically unrealistic. Since the formed oxide layer spalled off during the cooling period, the Ni 20 Cr 4 Al alloy cannot be used as material for cyclic oxidation. To what extent ThO2 particles dispersed in the alloy can prevent a spalling effect of the oxid film is at present an open question.