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1.

001-es BibID:BIBFORM033706
035-os BibID:PMID:8637885 WOS:A1996UB12100030
Első szerző:Halmos Gábor (gyógyszerész, receptorfarmakológus, experimentális onkológus)
Cím:Down-regulation of pituitary receptors for luteinizing hormone-releasing hormone (LH-RH) in rats by LH-RH antagonist Cetrorelix / Gabor Halmos, Andrew V. Schally, Jacek Pinski, Manuel Vadillo-Buenfil, Kate Groot
Dátum:1996
ISSN:0027-8424
Megjegyzések:Antagonists of luteinizing hormone-releasing hormone (LH-RH), unlike the LH-RH agonists, suppress gonadotropins and sex steroid secretion immediately after administration, without initial stimulatory effects. [Ac-D-Nal(2)1,D-Ph(4Cl)2,D-Pal(3)3,D-Cit6,D-Ala10]LH-R H (SB-75; Cetrorelix) is a modern, potent antagonistic analog of LH-RH. In this study, the binding characteristics of receptors for LH-RH in membrane fractions from rat anterior pituitaries were investigated after a single injection of Cetrorelix at a dose of 100 microg per rat. To determine whether the treatment with Cetrorelix can affect the concentration of measurable LH-RH binding sites, we applied an in vitro method to desaturate LH-RH receptors by chaotropic agents such as manganous chloride (MnCl2) and ammonium thiocyanate (NH4SCN). Our results show that the percentages of occupied LH-RH receptors at 1, 3, and 6 h after administration of Cetrorelix were approximately 28%, 14%, and 10%, respectively, of total receptors. At later time intervals, we could not detect occupied LH-RH binding sites. Ligand competition assays, following in vitro desaturation, demonstrated that rat pituitary LH-RH receptors were significantly (P < 0.01) down-regulated for at least 72 h after administration of Cetrorelix. The lowest receptor concentration was found 3-6 h after Cetrorelix treatment and a recovery in receptor number began within approximately 24 h. The down-regulation of LH-RH binding sites induced by Cetrorelix was accompanied by serum LH and testosterone suppression. Higher LH-RH receptor concentrations coincided with elevated serum hormone levels at later time intervals. Our results indicate that administration of LH-RH antagonist Cetrorelix produces a marked down-regulation of pituitary receptors for LH-RH and not merely an occupancy of binding sites.
Tárgyszavak:Orvostudományok Gyógyszerészeti tudományok idegen nyelvű folyóiratközlemény külföldi lapban
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Megjelenés:Proceedings of The National Academy of Sciences of The United States of America. - 93 : 6 (1996), p. 2398-2402. -
További szerzők:Schally, Andrew Victor Pinski, Jacek Vadillo-Buenfil, Manuel Groot, Kate
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2.

001-es BibID:BIBFORM033687
035-os BibID:WOS:A1997XJ25000027
Első szerző:Jungwirth, Andreas
Cím:Inhibition of growth of androgen-independent DU-145 prostate cancer in vivo by luteinising hormone-releasing hormone antagonist Cetrorelix and bombesin antagonists RC-3940-II and RC-3950-II / A. Jungwirth, J. Pinski, G. Galvan, G. Halmos, K. Szepeshazi, R. Z. Cai, K. Groot, M. Vadillo-Buenfil, A. V. Schally
Dátum:1997
ISSN:0959-8049
Megjegyzések:The aim of this study was to test the antagonist of LH-RH (Cetrorelix), agonist [D-Trp6]LH-RH (triptorelin) and new bombesin antagonists RC-3940-II and RC-3950-II for their effect on the growth of an androgen-independent prostate cancer cell line, DU-145, xenografted into nude mice. Xenografts were grown in male nude mice, and after 4 weeks, the animals were treated either with saline (control) or with one of the analogues. One group of mice was given a combination of Cetrorelix and RC-3950-II. Treatment was given for 4 weeks. Tumour and body weights, and tumour volumes were measured. At sacrifice, tumours were dissected for histological examination and receptor studies. Serum was collected for measurement of hormone levels. The final tumour volume in control animals injected with saline was 577 +/- 155 mm3 and that of animals treated with Cetrorelix only 121.4 +/- 45 mm3 (P < 0.01). Bombesin antagonists RC-3940-II and RC-3950-II also significantly reduced DU-145 tumour volume in nude mice to 84.9 +/- 19.9 and 96.8 +/- 28 mm3, respectively. Agonist [D-Trp6]LH-RH did not significantly inhibit tumour growth. Serum levels of LH were decreased to 0.08 +/- 0.02 ng/ml (P < 0.05) in the Cetrorelix treated group as compared to 1.02 +/- 0.1 ng/ml for the controls, and testosterone levels were reduced to castration levels (0.01 +/- 0.01 ng/ml). Specific receptors for EGF and LH-RH in DU-145 tumours were significantly downregulated after treatment with Cetrorelix, RC-3940-II and RC-3950-II. Although LH-RH could be a local regulator of growth of prostate cancer, the fall in LH-RH receptors is not fully understood and the inhibitory effects of Cetrorelix and bombesin antagonists on DU-145 tumour growth might be attributed at least in part to a downregulation of EHF receptors. Since Cetrorelix and bombesin antagonists inhibit growth of androgen-independent DU-145 prostate cancers, these compounds could be considered for the therapy of advanced prostate cancer in men, especially after relapse.
Tárgyszavak:Orvostudományok Gyógyszerészeti tudományok idegen nyelvű folyóiratközlemény külföldi lapban
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Megjelenés:European Journal of Cancer. - 33 : 7 (1997), p. 1141-1148. -
További szerzők:Pinski, Jacek Galvan, Georg Halmos Gábor (1962-) (gyógyszerész, receptorfarmakológus, experimentális onkológus) Szepesházi Károly Cai, Ren-Zhi Groot, Kate Vadillo-Buenfil, Manuel Schally, Andrew Victor
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3.

001-es BibID:BIBFORM033823
035-os BibID:PMID:8754771 WOS:A1996UY11100040
Első szerző:Pinski, Jacek
Cím:Chronic administration of the luteinizing hormone-releasing hormone (LHRH) antagonist cetrorelix decreases gonadotrope responsiveness and pituitary LHRH receptor messenger ribonucleic acid levels in rats / Jacek Pinski, Najib Lamharzi, Gábor Halmos, Kate Groot, Andreas Jungwirth, Manuel Vadillo-Buenfil, Sham S. Kakar, Andrew V. Schally
Dátum:1996
ISSN:0013-7227
Megjegyzések:Continuous exposure to LHRH or its agonistic analogs results in a reduction of LHRH receptor sites and messenger RNA (mRNA) transcripts as well as in desensitization of the pituitary gonadotropes. To determine, whether LHRH antagonists might be similar in this respect to the agonists, we treated male rats for 4 weeks with daily sc injections of LHRH antagonist [Ac-D-Nal2,Phe(4Cl)2,D-Pal(3)3, D-Cit6,D-Ala10]LHRH (Cetrorelix acetate) or LHRH agonist, [D-Trp6]LHRH, in doses of 100 micrograms/animal-day. Another group of rats received a single im injection of 4.5 mg Cetrorelix pamoate depot, a sustained delivery formulation of the LHRH antagonist. An iv stimulation test with LHRH (200 ng/rat) was performed after 4 weeks of treatment. The rats were killed, and pituitary LHRH receptor characteristics were measured by RRA. To examine the effect of LHRH antagonist treatment on the expression of the pituitary LHRH receptor gene, some of the rats injected with Cetrorelix pamoate depot were killed after 2 weeks, and levels of LHRH receptor mRNA were determined by Northern blot and dot blot hybridization to a 32P-labeled rat complementary DNA probe. Our data show that LHRH-stimulated LH secretion at 30 min was suppressed by approximately 33% (P < 0.01) in rats pretreated with [D-Trp6]LHRH compared to that in animals injected with LHRH alone. Pretreatment of the rats with the LHRH antagonist suppressed the LH response to LHRH more markedly, the LH levels at 30 min were decreased by 89.8% and 96% in groups treated with Cetrorelix acetate and Cetrorelix pamoate depot, respectively. The testosterone response was virtually abolished in groups receiving Cetrorelix. The concentration of pituitary receptors for LHRH fell by 69% in the [D-Trp6]LHRH group, whereas the reductions in the Cetrorelix acetate group and in the group that received Cetrorelix pamoate depot were 77% and 82%, respectively. Treatment with Cetrorelix pamoate depot led to a 75-80% decrease in the levels of 5.0- and 4.5-kilobase forms of LHRH receptor mRNA compared to those in the control group. Dot blot analysis also showed 83% reduction in the mRNA for LHRH receptor. In conclusion, these data demonstrate that prolonged administration of LHRH antagonists such as Cetrorelix causes an impairment of gonadotropin secretion and a marked decrease in the levels of LHRH receptors as well as in the expression of the LHRH receptor gene. Thus, the down-regulation of pituitary LHRH receptors produced by LHRH antagonists appears to be similar to that resulting from the agonists.
Tárgyszavak:Orvostudományok Gyógyszerészeti tudományok idegen nyelvű folyóiratközlemény külföldi lapban
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Megjelenés:Endocrinology. - 137 : 8 (1996), p. 3430-3436. -
További szerzők:Lamharzi, Najib Halmos Gábor (1962-) (gyógyszerész, receptorfarmakológus, experimentális onkológus) Groot, Kate Jungwirth, Andreas Vadillo-Buenfil, Manuel Kakar, Sham S. Schally, Andrew Victor
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4.

001-es BibID:BIBFORM033816
035-os BibID:PMID:21541617 WOS:A1996VU54900002
Első szerző:Pinski, Jacek
Cím:Inhibition of growth of human small cell and non-small cell lung carcinomas by antagonists of growth hormone-releasing hormone (GH-RH) / Jacek Pinski, Andrew V. Schally, Andreas Jungwirth, Kate Groot, Gábor Halmos, Patricia Armatis, Márta Zarandi, Manuel Vadillo-Buenfil
Dátum:1996
Megjegyzések:Insulin-like growth factors-I and-II (IGF-I and IGF-II) may be involved in the proliferation of human lung carcinomas. The purpose of this study was to investigate the effects of two potent antagonists of growth hormone-releasing hormone (GH-RH), MZ-4-71 and MZ-5-156 on the growth of the H69 human small cell lung cancer (SCLC) and H157 non-SCLC (NSCLC) lines transplanted into nude mice or cultured in vitro. Nude mice bearing H69 and H157 tumors were treated for 3-5 weeks with MZ-4-71 or MZ-5-156 injected s.c. twice a day at a dose of 20 mu g/animal. Growth of H69 and H157 tumors in nude mice was significantly inhibited by MZ-4-71 and MZ-5-156 as shown by a reduction in tumor volume and weight. In animals bearing H157 NSCLC, treatment with MZ-4-71 decreased IGF-I and IGF-II levels in tumor tissue. Levels of IGF-I, but not of IGF-II in serum and liver tissue of H157 tumor-bearing nude mice treated with MZ-4-71 were decreased. High affinity binding sites for ICF-I were demonstrated on membranes of H69 and H157 tumors. In cell cultures, the proliferation rate of H69 SCLC cells was suppressed by 10(-7)-10(-5) M MZ-4-71, but H157 NSCLC line was only inhibited by 10(-5) M antagonist. Our findings demonstrate that the GHRH antagonists MZ-4-71 and MZ-5-156 can inhibit the growth of SCLC and NSCLC. This new approach to the management of lung cancer merits further investigation.
Tárgyszavak:Orvostudományok Gyógyszerészeti tudományok idegen nyelvű folyóiratközlemény külföldi lapban
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Megjelenés:International journal of oncology. - 9 : 6 (1996), p. 1099-1105. -
További szerzők:Schally, Andrew Victor Jungwirth, Andreas Groot, Kate Halmos Gábor (1962-) (gyógyszerész, receptorfarmakológus, experimentális onkológus) Armatis, Patricia Zarándi Márta Vadillo-Buenfil, Manuel
Internet cím:Intézményi repozitóriumban (DEA) tárolt változat
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5.

001-es BibID:BIBFORM033663
035-os BibID:PMID:10480336 WOS:000082305800002
Első szerző:Szepesházi Károly
Cím:Growth inhibition of experimental pancreatic cancers and sustained reduction in epidermal growth factor receptors during therapy with hormonal peptide analogs / Karoly Szepesházi, Gabor Halmos, Andrew V. Schally, José M. Arencibia, Kate Groot, Manuel Vadillo-Buenfil, Eulalia Rodriguez-Martin
Dátum:1999
ISSN:0171-5216
Megjegyzések:Reduction in receptors for epidermal growth factor (EGF) in cancers appears to be one of the principal mechanisms through which peptide hormone analogs can inhibit tumor growth. In this study, hamsters with nitrosamine-induced pancreatic cancers were treated for 8 weeks with bombesin/gastrin-releasing peptide (GRP) antagonist RC-3095, somatostatin analog RC-160 or the luteinizing hormone-releasing hormone antagonist Cetrorelix, using sustained delivery systems releasing 20, 35 and 20 microg analog/ day respectively. To establish the pattern of changes in the number and affinity of EGF receptors on tumors, groups of animals were sacrificed at regular intervals during therapy. Chronic treatment with RC-3095 or Cetrorelix resulted in an early (day 10) and sustained reduction (71% or 69% respectively) in EGF receptors on pancreatic tumors. In contrast, RC-160 decreased receptor concentration by 60% only after 20 days. Among the histological characteristics of proliferation, the decrease in argyrophilic nucleolar organizer regions, but not apoptotic and mitotic indices, showed a correlation with the fall in EGF receptors. The concentration of the receptors returned to the control level 4 days after cessation of chronic treatment with RC-3095. The effect of single injections of RC-3095, RC-160 and Cetrorelix on EGF receptors was also investigated. RC-160 decreased the number of EGF receptors on pancreatic cancers by 31% 3 h after administration, but the receptors had returned to normal level at 6 h. RC-3095 and Cetrorelix caused a 67% and 59% decline, respectively, in EGF receptors only 6 h after injection and the concentration of receptors remained low for 24 h. Thus, the pattern of downregulation of EGF receptors in pancreatic cancers appears to depend on the peptide used for therapy. Since the antitumor effect may be the result of the fall in EGF receptors in cancers, information on the time course of changes in these receptors during treatment with these analogs may lead to an improvement in therapeutic regimens.
Tárgyszavak:Orvostudományok Gyógyszerészeti tudományok idegen nyelvű folyóiratközlemény külföldi lapban
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Megjelenés:Journal of Cancer Research and Clinical Oncology. - 125 : 8-9 (1999), p. 444-452. -
További szerzők:Halmos Gábor (1962-) (gyógyszerész, receptorfarmakológus, experimentális onkológus) Schally, Andrew Victor Arencibia, José M. Groot, Kate Vadillo-Buenfil, Manuel Rodriguez-Martin, Eulalia
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