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Endocrinology. 1999 Mar;140(3):1048-53.
Regulation of estrogen sulfotransferase expression in Leydig cells by cyclic adenosine 3',5'-monophosphate and androgen.
Qian YM, Song WC.
Center for Experimental Therapeutics and Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia 19104, USA.
Estrogen sulfotransferase (EST) catalyzes the specific sulfonation and inactivation of estrogens. A common site for EST expression in mammalian species is the testicular Leydig cells. In previous in vivo studies, we have shown that testicular expression of EST is under the regulation of LH. Thus, EST expression in mouse Leydig cells was abolished by hypophysectomy, but could be restored by hCG injection. In this study, we have evaluated the downstream mechanisms by which LH exerts its regulatory effect on EST. Primary mouse Leydig cells were isolated and purified by collagenase digestion and Percoll density gradient centrifugation. They were cultured in serum-free medium at 32 C and treated with various agents for 24 or 48 h, and levels of EST messenger RNA and enzyme activity were determined. Consistent with the in vivo data suggesting an essential role of LH in regulating EST expression, treatment of primary mouse Leydig cells in vitro with 100 microM 8-bromo-dibutyryl cAMP [(Bu)2cAMP] increased EST expression 3- to 5-fold. The effect of (Bu)2cAMP was attenuated by the steroidogenesis inhibitor aminoglutethimide and was mimicked by the potent androgen 5alpha-dihydrotestosterone (5-DHT). The activity of 5-DHT in stimulating EST expression was blocked by the androgen receptor antagonist, hydroxyflutamide. These data suggested the involvement of androgen in (Bu)2cAMP-induced EST expression. Further evidence came from the study with interleukin-1beta, another agent known to suppress Leydig cell steroidogenesis by down-regulating P450c17 gene expression. Treatment of Leydig cells with 0.2 ng/ml interleukin-1beta inhibited (Bu)2cAMP-induced EST expression, which was overcome by the addition of 5-DHT. Finally, in the testis-feminized mouse (Tfm) in which the androgen receptor is nonfunctional due to a frameshift mutation, testicular EST expression is completely absent, whereas messenger RNAs of steroidogenic enzymes such as P450c17 and 3beta-hydroxysteroid dehydrogenase are relatively abundant. We conclude that, by acting as an autocrine or paracrine factor, androgen plays an essential role in the regulation of estrogen sulfotransferase expression in Leydig cell by LH and cAMP.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10067824&dopt=Abstract
Eur J Neurosci. 1999 Feb;11(2):632-46.
Inhibition of collagen IV deposition promotes regeneration of injured CNS axons.
Stichel CC, Hermanns S, Luhmann HJ, Lausberg F, Niermann H, D'Urso D, Servos G, Hartwig HG, Muller HW.
Department of Neurology, Heinrich-Heine-University Dusseldorf, Germany.
Scarring impedes axon regrowth across the lesion site and is one major extrinsic constraint to effective regeneration in the adult mammalian central nervous system. In the present study we determined whether specific biochemical or immunochemical modulation of one major component of the scar, the basal membrane (BM), would provide a means to stimulate axon regeneration in the mechanically transected postcommissural fornix of the adult rat. Basal membrane developed within the first 2 weeks after transection in spatiotemporal coincidence with the abrupt growth arrest of spontaneously regrowing axons. Local injection of anticollagen IV antibodies or alpha, alpha'-dipyridyl, an inhibitor of collagen triple helix formation and synthesis, significantly reduced lesion-induced BM deposition. This treatment allowed massive axon elongation across the lesion site. Anterograde tracing provided unequivocal evidence that regenerating axons follow their original pathway, reinnervate the appropriate target, the mammillary body, and become remyelinated with compact myelin. Presynaptic electrophysiological recordings of regenerated fibre tracts showed recovery to nearly normal conduction properties. Our results indicate that lesion-induced BM is an impediment for successful axonal regeneration and its reduction is a prerequisite and sufficient condition for regrowing axons to cross the lesion site.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10051764&dopt=Abstract
Hepatology. 1999 Mar;29(3):710-8.
Endothelial cells lining transjugular intrahepatic portasystemic shunts originate in hepatic sinusoids: implications for pseudointimal hyperplasia.
Sanyal AJ, Mirshahi F.
Department of Internal Medicine, Medical College of Virginia campus of Virginia Commonwealth University, Richmond, VA 23298-0711, USA. krrobersc.vcu.edu
The phenotype of the endothelial cells (ECs) in the pseudointima of transjugular intrahepatic portasystemic shunts (TIPS) and the mechanisms of pseudointima formation after TIPS were unknown. We hypothesized that TIPS were lined by hepatic sinusoidal ECs, which stimulated the migration of smooth muscle cells (SMCs) into the pseudointima and their proliferation. Studies were done with the following specific aims: (1) isolation of ECs from TIPS pseudointima and comparison of their phenotype with human cirrhotic sinusoidal and vascular ECs derived from hepatic and portal veins as well as aorta, and (2) testing of the effects of TIPS ECs on TIPS-derived SMC migration and proliferation. ECs were isolated from eight TIPS retrieved from liver explants by immunomagnetic separation using monodispersed magnetizable polystyrene beads (Dynabeads M-450) coated with Ulex Europeus 1. EC phenotypes were examined by transmission electron microscopy, factor VIII-related antigen, CD31, CD14, and CD34 expression, uptake of acetylated LDL and secretion of type IV collagen. The effects of EC-conditioned media on SMC migration and proliferation were tested in multiwell chemotaxis chambers and by cell counting, respectively. ECs were obtained from TIPS pseudointima with >95% purity. The phenotype of TIPS-derived ECs matched that of cirrhotic sinusoidal endothelium (both expressed CD14) and differed from that of vascular endothelium (CD14 negative, Weibel-Palade positive). Conditioned media from both stenosed (n = 3) and nonstenosed (n = 3) TIPS-derived endothelial cells produced a marked (>100%) P <.001 increase in migration as well as (up to 88%) P <.01 proliferation of SMCs from both stenosed (n = 3) as well as nonstenosed TIPS (n = 3). These data indicate that TIPS pseudointima are lined by hepatic sinusoidal endothelial cells, which stimulate pseudointima formation by increasing SMC migration and proliferation.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10051472&dopt=Abstract
Hepatology. 1999 Mar;29(3):858-67.
A histone deacetylase inhibitor, trichostatin A, suppresses myofibroblastic differentiation of rat hepatic stellate cells in primary culture.
Niki T, Rombouts K, De Bleser P, De Smet K, Rogiers V, Schuppan D, Yoshida M, Gabbiani G, Geerts A.
Laboratory for Cell Biology and Histology, Phytochemistry, and Toxicology, Faculty of Medicine and Pharmacy, Free University of Brussels (VUB), Belgium.
Hepatic stellate cells are the major cellular sources of extracellular matrix in chronic liver diseases leading to fibrosis. We explored the antifibrogenic effect of two histone deacetylase inhibitors, sodium butyrate and trichostatin A (TSA), on this cell type in vitro. Primary hepatic stellate cells as well as culture activated cells were exposed to butyrate (0.01-1 mmol/L) or TSA (1-100 nmol/L); their effect on collagen types I and III and smooth muscle alpha-actin was examined by quantitative immunoprecipitation and by Northern analysis. Their antiproliferative effect was examined by 3H-thymidine incorporation and cell counting. Hyperacetylation of histones was demonstrated by acid urea/Triton-X-100 (AUT) polyacrylamide gel electrophoresis. Possible cytotoxic effects were judged on stellate cells by evaluating de novo total protein synthesis, and on hepatocytes by measuring lactate dehydrogenase (LDH) leakage, albumin secretion, and epoxide hydrolase and ethoxycoumarin O-deethylase activity. TSA at 100 nmol/L and butyrate at 1 mmol/L retarded the morphological changes characteristic for activation of primary stellate cells. TSA at 100 nmol/L inhibited synthesis of collagen types I and III and smooth muscle alpha-actin by 62%, 70%, and 88%. Butyrate at 1 mmol/L showed a modest inhibitory effect on collagen type III and smooth muscle alpha-actin, but had no effect on collagen type I. Northern analysis suggested that these inhibitory effects on collagen type III and smooth muscle alpha-actin were transcriptional, while the effect on collagen type I was largely posttranscriptional. At 100 nmol/L, TSA strongly suppressed proliferation of primary hepatic stellate cells. Inhibition of activation of stellate cells was preceded by hyperacetylation of histone H4. When tested on cells at day 14 in culture, butyrate had no inhibitory effects on the synthesis of collagens or smooth muscle alpha-actin. One hundred or 10 nmol/L TSA modestly inhibited the synthesis of collagens type I (-24%,-22%) and III (-34%,-22%), and smooth muscle alpha-actin (-27%,-12%). We conclude that TSA inhibits transdifferentiation of stellate cells into myofibroblasts by interfering with the level of acetylation of histone H4.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10051490&dopt=Abstract
Blood. 1999 Mar 15;93(6):1959-68.
Conformational changes in the A3 domain of von Willebrand factor modulate the interaction of the A1 domain with platelet glycoprotein Ib.
Obert B, Houllier A, Meyer D, Girma JP.
INSERM U.143, Hopital de Bicetre, Paris, France.
Bitiscetin has recently been shown to induce von Willebrand factor (vWF)-dependent aggregation of fixed platelets (Hamako J, et al, Biochem Biophys Res Commun 226:273, 1996). We have purified bitiscetin from Bitis arietans venom and investigated the mechanism whereby it promotes a form of vWF that is reactive with platelets. In the presence of bitiscetin, vWF binds to platelets in a dose-dependent and saturable manner. The binding of vWF to platelets involves glycoprotein (GP) Ib because it was totally blocked by monoclonal antibody (MoAb) 6D1 directed towards the vWF-binding site of GPIb. The binding also involves the GPIb-binding site of vWF located on the A1 domain because it was inhibited by MoAb to vWF whose epitopes are within this domain and that block binding of vWF to platelets induced by ristocetin or botrocetin. However, in contrast to ristocetin or botrocetin, the binding site of bitiscetin does not reside within the A1 domain but within the A3 domain of vWF. Thus, among a series of vWF fragments, 125I-bitiscetin only binds to those that overlap the A3 domain, ie, SpIII (amino acid [aa] 1-1365), SpI (aa 911-1365), and rvWF-A3 domain (aa 920-1111). It does not bind to SpII corresponding to the C-terminal part of vWF subunit (aa 1366-2050) nor to the 39/34/kD dispase species (aa 480-718) or T116 (aa 449-728) overlapping the A1 domain. In addition, bitiscetin that does not bind to DeltaA3-rvWF (deleted between aa 910-1113) has no binding site ouside the A3 domain. The localization of the binding site of bitiscetin within the A3 domain was further supported by showing that MoAb to vWF, which are specific for this domain and block the interaction between vWF and collagen, are potent inhibitors of the binding of bitiscetin to vWF and consequently of the bitiscetin-induced binding of vWF to platelets. Thus, our data support the hypothesis that an interaction between the A1 and A3 domains exists that may play a role in the function of vWF by regulating the ability of the A1 domain to bind to platelet GPIb.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10068669&dopt=Abstract
Loss of hair changes the appearance of a person, and the identity of the person in social context to a certain extent.
Hair growth is a complex biological process, which has not yet been completely understood. A multitude of therapeutic measures, including drugs, surgery, and suppelements have been made available, and used. However, due to the diversity of the problems underlying hair loss, there is no single solution for all hair loss cases. Most of chemical drugs and hair transplantation surgeries are not free from varying degrees of undesirable side effects on health.
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