bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regulation of the mesangial cell myofibroblast phenotype by actin polymerization
Authors: Patel Keyur , Harding Pamela , Haney Lisa B. , Glass William F. 
Published: April 2003

AbstractMesangial cells in diverse glomerular diseases become myofibroblast‐like, characterized by activation of smooth muscle α‐actin (α‐SMA) expression. In cultured mesangial cells, serum‐deprivation markedly increases α‐SMA expression, cell size, and stress fiber formation. Since stress fibers are assembled from actin monomers, we investigated the hypothesis that alterations in stress fiber formation regulate α‐SMA expression and hypertrophy. Human mesangial cells were treated with agents that disrupt or stabilize actin stress fibers. Depolymerization of actin stress fibers in serum‐deprived cells with actin‐depolymerizing agents, cytochalasin B (CytB) and latrunculin B (LatB), or with inhibitors of Rho‐kinase, Y‐27632 and HA‐1077 decreased α‐SMA mRNA as judged by Northern blot analysis. Western blot analysis showed that CytB also reduced α‐SMA protein levels. In serum‐fed cells, agents that stabilized actin stress fibers, jasplakinolide (Jas) and phalloidin, increased α‐SMA mRNA and protein. Treatment of human or rat mesangial cells with CytB, LatB, or Y‐27632 decreased α‐SMA promoter activity. In contrast, Jas increased promoter activity 5.6‐fold in rat mesangial cells. The presence of an RNA polymerase inhibitor blocked degradation of α‐SMA mRNA in cells treated with CytB suggesting that destabilization of this message is dependent on a newly transcribed or rapidly degraded factor. Inhibition of actin polymerization by CytB, LatB, Y‐27623, and HA‐1077 inhibited incorporation of 3[H]‐leucine into newly synthesized protein. Additionally, CytB and LatB decreased cell volume as determined by flow cytometry. Collectively, these results indicate that the state of polymerization of the actin cytoskeleton regulates α‐SMA expression, hypertrophy, and myofibroblast differentiation in mesangial cells. © 2003 Wiley‐Liss, Inc.
Tensile stress induces α‐adaptin C production in mouse calvariae in an organ culture: Possible involvement of endocytosis in mechanical stress‐stimulated osteoblast differentiation
Authors: Shimomura Junko , Ishibashi Osamu , Ikegame Mika , Yoshizawa Tatsuya , Ejiri Sadakazu , Noda Tadashi , Kawashima Hiroyuki 
Published: April 2003

AbstractWe previously demonstrated that tensile stress (TS)‐induced osteoblast differentiation eventually led to osteogenesis in an organ culture of mouse calvarial sutures. In the present study, we employed RNA‐fingerprinting using an arbitrarily primed polymerase chain reaction (RAP‐PCR) to identify α‐adaptin C, a component of the endocytosis machinery AP2, as a TS‐inducible gene. Protein production, as well as the gene expression of α‐adaptin C, was induced by TS as early as 3 h following the initiation of loading. In situ hybridization and immunohistochemical analysis revealed that the induction of α‐adaptin C mostly occurred in fibroblastic cells in the sutures, suggesting that it precedes TS‐induced osteoblast differentiation. Consistent with this result, TS significantly increased the number of coated pits (CPs) and coated vesicles (CVs) in the undifferentiated fibroblastic cells but not in the osteoblastic cells around calvarial bones. Further, TS‐induced osteoblast differentiation was suppressed when endocytosis was inhibited by potassium depletion. These results, taken together, suggest that TS accelerates osteoblast differentiation and osteogenesis, possibly through the induction of the α‐adaptin C expression and consequent activation of receptor‐mediated endocytosis. © 2003 Wiley‐Liss, Inc.
Differential physiological expression of the invertebrate 2Na+/1H+ antiporter in single epithelial cell type suspensions of lobster hepatopancreas
Authors: Mandal Prabir K. , Mandal Anita , Ahearn Gregory A. 
Published: April 2003

AbstractLobster (Homarus americanus) hepatopancreas is a complex, heterogeneous tissue composed of four epithelial cell types that individually contribute to the overall functional properties of digestion, absorption, secretion, and detoxification. Previous studies, using purified hepatopancreatic brush border membrane vesicles, have described the properties of an electrogenic, 2Na+/1H+ antiporter in this tissue that regulates the absorption and secretion of these cations. These studies were not able to localize this cation exchange phenomenon to specific epithelial cell types. In the present study, sodium/proton exchange by purified, single cell, suspensions of lobster (Homarus americanus) hepatopancreatic epithelium was investigated using a centrifugal elutriation method to cleanly separate the four individual cell types for subsequent physiological characterization. Results indicate that all four hepatopancreatic epithelial cell types possessed the 2Na+/1H+ antiporter as a result of its unique sigmoidal influx properties. Hill Coefficients, measures of transport sigmodicity obtained from kinetic analyses of 22Na+ influx by single cell type suspensions, varied from 1.56±0.30 (R‐cell suspensions) to 2.79±0.41 (F‐cell suspensions), suggesting that different numbers of sodium ions may be accommodated by each cell type. Both calcium and zinc were competitive inhibitors of 22Na+ influx in E‐cells (calcium Ki = 105.1±5.2 µM; zinc Ki=46.2±7.8 µM), but the extent to which these divalent cations inhibited monovalent cation transport by each cell type varied. It is concluded that different isoforms of the electrogenic 2Na+/1H+ antiporter may be present in each hepatopancreatic cell type and thereby contribute in differing degrees to the cation regulatory functions performed by the overall organ. J. Exp. Zool. 297A:32–44, 2003. © 2003 Wiley‐Liss, Inc.
Viewing chelonian reproductive ecology through acoustic windows: Cranial and inguinal perspectives
Authors: Henen Brian T. , Hofmeyr Margaretha D. 
Published: April 2003

AbstractUltrasonography is a powerful new tool in reproductive physiology and ecology but quantitative evaluations of acoustic window efficacies are necessary to assess methodological accuracy. We evaluated the efficacy of the left inguinal, right inguinal and cranial acoustic windows for detecting ovarian follicles and oviducal eggs in three tortoise species. Incorporating cranial results improved upon inguinal efficacies for detecting follicles in the three species, and for detecting eggs in Chersina angulata, which had small inguinal apertures for its body size. The cranial window provided the best follicle results (highest numbers detected) but the left inguinal window provided the best egg results. This asymmetry was probably due to the primarily posterior position of the oviducts (eggs) and the pliable ovarian sheets allowing follicles to move cranially. The left‐right asymmetry may result from intestinal asymmetry (i.e., between the cecum and descending colon) in obscuring ultrasound transmission or displacing follicles and eggs. Seasonal influences upon efficacies varied with species, partially due to species differences in a) reproductive cycles and b) size and number of follicles and eggs. We attributed other efficacy differences among species to differences in body size and shell morphology, especially the inguinal apertures. Correlation analyses revealed strong individual influences upon window efficacy, suggesting that individuals varied in the position of follicles and eggs and the degree of obfuscation by nonreproductive structures. The paucity of correlations between efficacies and body size reflects the complex interactions of body size, shell morphology, reproductive structures and reproductive cycles on efficacies. J. Exp. Zool. 297A:88–104, 2003. © 2003 Wiley‐Liss, Inc.
Characterization of the effects of vasoactive substances on the bulbus arteriosus of the eel, Anguilla rostrata
Authors: Evans David H. , Harrie Ann C. , Kozlowski Matthew S. 
Published: April 2003

AbstractThe fish bulbus arteriosus (BA) smoothes cardiac output by expanding during cardiac systole and rebounding during diastole, thereby providing constant perfusion of the gills downstream. Published data have demonstrated innervation of the teleost BA and shown that the tension and compliance of the BA responded to vasoactive agonists, such as epinephrine and acetylcholine, suggesting that the BA was more than a mere “windkessel.” To examine vasoactivity in the BA more directly, we measured the responses of isolated tissue rings from the BA of the eel, Anguilla rostrata to a suite of putative vasoactive agonists, which had been shown to affect vascular smooth muscle in a variety of teleosts. The BA of the eel was insensitive to acetylcholine but constricted when endothelin (ET‐1) was applied. Nitric oxide, sodium nitroprusside (SNP; NO donor), natriuretic peptides (NP), and prostaglandin E1 (but not the prostacyclin agonist carbaprostacyclin) produced significant dilation in the BA. Since both ET‐1 and sarafotoxin S6c produced concentration‐dependent constriction, it appears that endothelin receptor B‐type (ETB) receptors (and possibly ETA receptors) are present. The dilation produced by SNP was also concentration dependent, as were the dilations produced by porcine C‐type natriuretic peptide, eel atrial natriuretic peptide (NP receptor agonists), Sulprostone and Butaprost (PGE receptor agonists). Our data demonstrate that the BA of eel is responsive to a variety of vasoactive agonists, suggesting that the BA is under neurohumoral control. The role of agonist‐induced changes in BA tension in fish cardiovascular physiology remains to be determined, as do the specific receptor types involved. J. Exp. Zool. 297A:45–51, 2003. © 2003 Wiley‐Liss, Inc.
Compensation for hypercapnia by a euryhaline elasmobranch: Effect of salinity and roles of gills and kidneys in fresh water
Authors: Choe Keith Patrick , Evans David H. 
Published: April 2003

AbstractSpecimens of the euryhaline elasmobranch, Dasyatis sabina were acclimated to seawater and fresh water, and exposed to normocapnic (air) and hypercapnic (1% CO2 in air) environmental water. Blood pH, P, and [HCO], as well as whole‐animal net‐acid excretion, were measured for up to 24 h of hypercapnia. In a separate experimental series, urine was collected from freshwater acclimated stingrays during 8 h of normocapnia and hypercapnia. Stingrays in both salinities at least partially compensated for the respiratory acidosis by accumulating HCO in their extracellular spaces. The degree of compensation for blood pH was 88.5% in seawater, but only 31.0% in fresh water after 24 h of hypercapnia. Whole‐animal net‐acid excretion was also greater in seawater than in fresh water, as was the increase in extracellular fluid [HCO]. Mean urinary net‐acid excretion rates were slightly negative, and never increased above normocapnic control rates during hypercapnia. Since whole‐animal net‐acid excretion rates increased with blood [HCO], and urinary excretion was always negative, the gills were probably the primary organ responsible for compensation from environmental hypercapnia. The faster, and more complete, compensation for hypercapnia in seawater than in fresh water for this euryhaline elasmobranch is consistent with data for euryhaline teleosts, and probably reflects Na+‐dependent mechanisms of branchial acid excretion. J. Exp. Zool. 297A:52–63, 2003. © 2003 Wiley‐Liss, Inc.
Vascular anatomy of the gills in a high energy demand teleost, the skipjack tuna (Katsuwonus pelamis)
Authors: Olson Kenneth R. , Dewar Heidi , Graham Jeffrey B. , Brill Richard W. 
Published: April 2003

AbstractTunas (family: Scombridae, Tribe: Thunnini) exhibit anatomical, physiological, and biochemical adaptations that dramatically increase the ability of their cardiorespiratory systems to transfer oxygen from the water to the tissues. In the present study the vascular anatomy of the skipjack tuna, Katsuwonus pelamis, gill was examined by light and scanning electron microscopic analysis of methyl methacrylate vascular corrosion replicas prepared under physiological pressure. The gill filament contains three distinct blood pathways, respiratory, interlamellar, and nutrient. The respiratory, or arterio‐arterial (AA) pathway, is the site of gas exchange and consists of the afferent and efferent filamental arteries (AFA and EFA) and arterioles (ALA and ELA) and the lamellae. Each ALA in the basal filament supplies ten or more lamellae and they anastomose with their neighbor to form a continuous vascular arcade. Four modifications in the lamellar circulation appear to enhance gas exchange efficiency. 1) The ALA deliver blood directly to the outer margin of the lamellae where unstirred boundary layer effects are predicted to be minimal and water PO2 highest. 2) Pillar cells are closely aligned along the outer boundary of the inlet side and the inner boundary of the outlet side of the lamellae to form multiple distributing and receiving blood channels. 3) Elsewhere in the lamella, pillar cells are aligned to form diagonal channels that direct blood from the outer to the inner lamellar margins, thereby reducing vascular resistance. 4) The lamellar sinusoid is especially widened near the efferent end to augment oxygen saturation of blood flowing through the inner margin. These adaptations, plus the presence of a bow‐shaped interlamellar septum, and a thinned filament core appear to decrease gill vascular resistance and maximize gas‐exchange efficiency. The interlamellar (IL) and nutrient systems originate from post‐lamellar vessels and are arterio‐venous (AV) pathways. IL vessels form an extensive ladder‐like lattice on both sides of the filamental cartilage and are supplied in part by narrow‐bore vessels from the medial wall of the EFA. Their function is unknown. Nutrient vessels are formed from the confluence of a myriad of tortuous, narrow‐bore vessels arising from the basal region of the EFA and from efferent branchial arteries. They re‐enter the filament and eventually drain into the IL system or filamental veins. As these AV pathways are retained despite considerable reduction in filamental tissue, it is evident that they are integral components of other non‐respiratory homeostatic activities of the gill. J. Exp. Zool. 297A:17–31, 2003. © 2003 Wiley‐Liss, Inc.
Synthesis of deuterium‐labeled 3‐O‐methyldopa and 4‐O‐methyldopa
Authors: Perera Aruna , Hyland Keith , Nguyen Hoa K. , Kane Robert R. 
Published: April 2003

AbstractConcise methods for the synthesis of 4‐hydroxy‐3‐[2H3]‐methoxyphenylalanine (3‐O‐[2H3]‐methydopa) and 3‐hydroxy‐4‐[2H3]‐methoxyphenylalanine (4‐O‐[2H3]‐methydopa) are described. The 3‐O‐[2H3]‐methydopa is a valuable internal standard for the tandem MS quantification of 3‐O‐methyldopa, a metabolite of value in the diagnosis of aromatic l‐amino acid decarboxylase (AADC) deficiency. Copyright © 2003 John Wiley & Sons, Ltd.
Asymmetric epoxidation of digeranyl by cultured cells of Nicotiana tabacum
Authors: Nakagawa Osamu , Shimoda Kei , Izumi Sunsuke , Hirata Toshifumi 
Published: April 2003

AbstractAsymmetric epoxidation of digeranyl, which is a squalene analog, with cultured cells of Nicotiana tabacum was investigated. Feeding of [8‐3H]‐digeranyl into the cultured cells of N. tabacum resulted in the formation of (3S)‐2,3‐epoxydigeranyl and 6,7‐epoxydigeranyl. It was found that the epoxidation of digeranyl with N. tabacum was highly stereoselective. Copyright © 2003 John Wiley & Sons, Ltd.
Synthesis of tritium labelled L783483 ‐ a PPARδ ligand
Authors: Grue‐Sørensen Gunnar , Høj Nicolaj 
Published: April 2003

AbstractThe potent peroxisome proliferator‐activated receptor (PPAR) δ ligand L783483 (3‐chloro‐4‐(3‐(7‐propyl‐3‐trifluoromethyl‐benzisoxazol‐6‐oxy)propylsulfanyl)phenylacetic acid) has been labelled with tritium via selective tritium/bromine exchange of 5‐bromo‐6‐(3‐bromopropyloxy)‐7‐propyl‐3‐trifluoromethyl‐benzisoxazole. [3H]‐L783483 had a specific activity of 529 GBq/mmol (14.3 Ci/mmol) and a radiochemical purity of 98%. Copyright © 2003 John Wiley & Sons, Ltd.
Chemical and enzymatic synthesis of tritium labelled coenzymes
Authors: Sidorov G. V. , Zverkov Yu. B. , Shram S. I. , Lazurkina T. Yu. , Myasoedov N. F. 
Published: April 2003

AbstractDetails of the synthesis of tritium labelled co enzymes‐nicotinamide adenine dinucleotide and coenzyme A by isotope exchange and enzymatic reactions are reported. It was established, that among the investigated chemical reactions, the most effective is solid state isotope exchange with gaseous tritium. This method was used to produce [3H] nicotinamide adenine dinucleotide (111 Ci/mmol), [3H] coenzyme A (3.9 Ci/mmol) and D‐[G‐3H] pantothenic acid (43 Ci/mmol). It was shown that most of the tritium in the labeled nicotinamide adenine dinucleotide and coenzyme A was localized in the nicotinamide (98%) and adenine (89%) sites, respectively. For synthesis of coenzymes labelled with tritium at other sites we developed enzymatic methods which used labelled precursors. Optimum conditions for enzymatic synthesis of [adenine‐3H] nicotinamide adenine dinucleotide from [2,8‐3H] ATP and [pantothenate‐3H] coenzyme A from D‐[G‐3H] pantothenic acid were determined. The tritium labelled acetyl coenzyme A was synthesized by acetylation of labelled coenzyme A with acetic anhydride. The methods chosen allow one to produce tritium labelled coenzymes at high specific activity. Copyright © 2003 John Wiley & Sons, Ltd.
[14C] and [3H]‐labelling of Ragaglitazar: A dual acting PPARα and PPARγ agonist with hypolipidemic and anti‐diabetic activity
Authors: Kristensen Jesper B. , Johansen Steen K. , Valsborg Jacob S. , Martiny Lars , Foged Christian 
Published: April 2003

AbstractCurrently, Ragaglitazar is being developed as a drug for the treatment of hyperglycaemia and hyperlipidemia in patients with type 2 diabetes. Here, we report the labelling of Ragaglitazar with carbon‐14 and tritium for in vivo and in vitro investigations. Two different carbon‐14 labelled as well as two different tritium labelled tracers of Ragaglitazar were synthesised. The carbon‐14 label was introduced from either ethyl bromo[2‐14C]acetate (5 steps/33% overall yield) or [U‐14C]phenoxazine (4 steps/48% overall yield). Tritium was incorporated either by catalytic tritiation of an alkene precursor followed by chiral HPLC separation (2 steps/17% overall yield) or by catalytic tritium–halogen exchange of an aryl bromide precursor (2 steps/68% overall yield). Copyright © 2003 John Wiley & Sons, Ltd.
Application of 1‐butyl‐3‐methylimidazolium hexafluorophosphate to Ir(I)‐catalyzed hydrogen isotope exchange labelling of substrates poorly soluble in dichloromethane
Authors: Salter Rhys , Bosser Isabelle 
Published: April 2003

AbstractSubstrate solubility remains a major limitation in Ir(I)‐catalyzed isotopic hydrogen exchange labelling. In the search for an alternative to the solvent dichloromethane, which is critical to the success of the reaction, we examined a series of ionic liquids for their suitability. Commercially available 1‐butyl‐3‐methylimidazolium hexafluorophosphate (abbreviated to [BMI][PF6]) was found to support efficient deuterium and tritium exchange labelling of N‐(4‐methoxyphenyl)‐N‐methyl benzamide 1 under standard conditions. The solvent dissolves both polar hydroxyl and carboxylic acid substituted acetanilides, providing isotopomers in unprecedentedly high deuterium incorporation as compared to dichloromethane. We report the application of [BMI][PF6] and its potential for extending the scope of Ir(I)‐catalyzed H/T exchange to more polar compounds. Copyright © 2003 John Wiley & Sons, Ltd.
Über die gültigkeit des viskositätsgesetzes bei polyoxydecansäuren
Authors: Staudinger Von H. , Berndt Fr. 
Published: April 2003

AbstractEs werden fünf Polyoxydecansäuren vom osmotischen Molekulargewicht 5000 bis 13 000 beschrieben, bei denen die beiden Endgruppenmolekulargewichte die gleiche Größe haben und die danach unverzweigte Moleküle haben. Da auch das viskosimetrische Molekulargewicht mit diesen Werten übereinstimmt, so wird auf die Gültigkeit des Viskositätsgesetzes geschlossen.Eine Gruppe von anderen Polyoxydecansäuren von gleichem und höherem Molekulargewicht hat verzweigte Moleküle, da das Endgruppenmolekulargewicht, bestimmt aus dem Carboxylgruppengehalt, niedriger ist als das osmotische Molekulargewicht und das andere Endgruppenmolekulargewicht. Die viskosimetrischen Molekulargewichte stimmen bei diesen verzweigten Polyestern nicht mit den Endgruppen molekulargewichten überein.Die Fasern aus unverzweigten und verzweigten Polyestern zeigen bemerkenswerte Unterschiede in der Festigkeit.
Über die gültigkeit des viskositätsgesetzes bei polyaminocapronsäuren
Authors: Staudinger Von H. , Schnell H. 
Published: April 2003

AbstractPolyaminocapronsäuren vom Molekulargewicht 1500—15 000 sind unverzweight, da die beiden Endgruppenmolekulargewichte mit dem viskosimetrischen Molekulargewicht übereinstimmen. Die Gültigkeit des Viskositätsgesetzes wurde bei diesen Polyaminocapronsäuren bis zu einem Molekulargewicht von 20 000 nachgewiesen. Es wird weiter eine Erklärung für die von A. Matthes gefundenen abweichenden Resultate gegeben. Der Zusammenhang zwischen Knickbruchfestigkeit von Fasern und Kettenlänge der Polymaide wird untersucht.
Die autox‐ und metallautox‐katalyse der polymerisation ungesättigter verbindungen
Authors: Kern von Werner 
Published: April 2003

AbstractMolekularer Sauerstoff kann unter geeigneten Bedingungen in Redox‐ und Metallredoxsystemen, welche die Polymerisation ungesättigter Verbindungen auslösen, die Rolle des Oxydationsmittels übernehmen. Die Autoxydation des Reduktionsmittels löst also die Polymerisation aus (Autoxkatalyse). Durch Zusatz von kationischem 2‐ oder 3‐wertigem Eisen tritt eine starke Beschleunigung der Polymerisation ein (Eisenautoxkatalyse). Zur Deutung wird angenommen, daß bei der Autoxydation der H‐Donatoren Radikale entstehen, die polymerisationsauslösend wirken. In kleinen Konzentrationen wirkt molekularer Sauerstoff in Verbindung mit autoxydabeln Reduktionsmitteln stark polymerisationsbeschleunigend, in hohen Konzentrationen aber polymerisationshemmend, da er dann die wachsenden Ketten abbricht.
Über den einbau peroxydischer katalysatoren in die makromoleküle von polymerisaten bei der polymerisation von methacrylsäuremethylester, vinylacetat und methacrylnitril
Authors: Kern von W. , Kämmerer H. 
Published: April 2003

AbstractEs werden die Reaktionsmöglichkeiten peroxydischer Katalysatoren bei der Polymerisation ungesättigter Verbindungen erörtert. Der Einbau kann prinzipiell beim Primärakt, bei der Wachstumsreaktion, beim Kettenabbruch oder bei einer Sekundärreaktion erfolgen. Beim Styrol erfolgt der Einbau von p‐Brombenzoylperoxyd beim Primärakt. Die Bromatomzahl (Anzahl der eingebauten Bromatome pro Makromolekül) ist in geringem Umfange von der Peroxydkonzentration bei der Polymerisation abhängig. so daß man mit einer Nebenreaktion rechnen muß. Während Polystyrolmakromoleküle im Durchschnitt 4 Bromatome enthalten, ergeben sich bei der Polymerisation des Methacrylsäuremethylesters bei 50°C mit p‐Brombenzoylperoxyd im Durchschnitt nur etwa 2 gekennzeichnete Endgruppen. Auch Vinylacetat zeigt bei der Polymerisation einen Einbau des peroxydischen Katalysators: doch ist die Bromatomzahl von der angewandten Peroxydkonzentration stark abhängig. Sie steigt mit wachsender Katalysatorkonzentration an; dieser Anstieg wird durch eine Sekundärreaktion oder eine Übertragungsreaktion verursacht.Der Einbau von p‐Brombenzoylperoxyd konnte auch bei Polymethacrylnitril wahrscheinlich gemacht werden. m‐Nitrobenzoylperoxyd ist als gekennzeichneter Katalysator für die Polymerisation des Vinylchlorids ungeeignet, da die Nitrogruppe die katalytische Wirkung des Peroxydes aufhebt.
Die beeinflussung der emulsionspolymerisation des butadiens durch reglung
Authors: Graulich von W. , Becker W. 
Published: April 2003

AbstractEs wurde die Reglung der Mischpolymerisation von Butadien mit Vinylverbindungen in Emulsion untersucht. Substanzen verschiedenster Konstitution wurden als Regler erkannt und ihr Einfluß auf den Verlauf der Polymerisation an Hand physikalisch‐chemischer Meßmethoden geprüft. Es konnte gezeigt werden, wie durch Anwendung dieser Methoden die Herstellung verbesserter Produkte möglich war.