Magnitude of 5-HT1B and 5-HT1A receptor activation in guinea-pig and rat brain: evidence from sumatriptan dimer-mediated [35S]GTPgammaS binding responses

The present study reports on G-protein activation by recombinant 5-HT receptors and by native 5-HT1A and 5-HT1B receptors in guinea-pig and rat brain using agonist-stimulated [35S]GTPgammaS binding responses mediated by a new 5-HT ligand, a dimer of sumatriptan. Dimerization of sumatriptan increased the binding affinity for h 5-HT1B (pKi: 9.22 vs. 7.79 for sumatriptan), h 5-HT1D (9.07 vs. 8.08) and also h 5-HT1A receptors (7.80 vs. 6.40), while the binding affinity for h 5-ht1E (6.67 vs. 6.19) and h 5-ht1F (7.37 vs. 7.78) receptors was not affected. Sumatriptan dimer (10 microM) stimulated [35S]GTPgammaS binding mainly in the superficial gray layer of the superior colliculi, hippocampus and substantia nigra of guinea-pig and rat coronal brain sections. This fits with the labelling by the 5-HT1B/1D receptor antagonist [3H] GR 125743. The observed [35S]GTPgammaS binding responses in the substantia nigra are likely to be mediated by stimulation of the 5-HT1B receptor subtype, since they were antagonized by the 5-HT1B inverse agonist SB 224289 (10 microM), and not by the 5-HT2A/1D antagonist ketanserin (10 microM). Quantitative assessment of the [35S]GTPgammaS binding responses in the substantia nigra of rat showed highly efficacious responses for both sumatriptan dimer and its monomer. In contrast, less efficacious agonist responses (51+/-10% and 35+/-13%, respectively) were measured in the guinea-pig substantia nigra. This may suggest that the G-protein coupling efficacy of 5-HT1B receptors is different between the substantia nigra of both species. In addition, the sumatriptan dimer also activated guinea-pig and rat hippocampal 5-HT1A receptors with high efficacy in contrast to sumatriptan. Therefore, dimerization of sumatriptan can be considered as a new approach to transform a partial 5-HT1A agonist into a more efficacious agonist. In conclusion, the sumatriptan dimer stimulates G-protein activation via 5-HT1B receptors besides 5-HT1A receptors in guinea-pig and rat brain. The magnitude of the 5-HT1B receptor responses is superior for sumatriptan and its dimer in rat compared to guinea-pig substantia nigra.     

Discovery of novel non-peptide CCR1 receptor antagonists

Ligands for the CCR1 receptor (MIP-1alpha and RANTES) have been implicated in a number of chronic inflammatory diseases, most notably multiple sclerosis and rheumatoid arthritis. Because these ligands share a common receptor, CCR1, we sought to discover antagonists for this receptor as an approach to treating these disorders. A novel series of 4-hydroxypiperidines has been discovered by high throughput screening (HTS) which potently inhibits the binding of MIP-1alpha and RANTES to the recombinant human CCR1 chemokine receptor. The structure-activity relationships of various segments of this template are described as the initial HTS lead 1 was optimized synthetically to the highly potent receptor antagonist 6s. This compound has been shown to have at least 200-fold selectivity for inhibition of CCR1 over other human 7-TM receptors, including other chemokine receptors. In addition, data obtained from in vitro functional assays demonstrate the functional antagonism of compound 6s and structurally related analogues against the CCR1 receptor in a concentration dependent manner. The discovery and optimization of potent and selective CCR1 receptor antagonists represented by compound 6s potentially represent a novel approach to the treatment of chronic inflammatory diseases.     

Acute and nongenomic effects of testosterone on isolated and perfused rat heart

Gonadal steroid hormones influence vascular tone and the development of hypertension. There are sex differences in the incidence of cardiovascular diseases, and great attention has been placed on the study of estrogen cardiovascular effects. However, there are only a few reports on the effects of testosterone on the vasculature. It is commonly accepted that the mechanism of the action of steroid hormones on target tissues is mediated through the binding of hormones to cytoplasmic or nuclear receptors. However, some studies indicate that steroid action can be extremely rapid and therefore unlikely to be through a genomic mechanism. The purpose of this study was to assess the effect of intravascularly confined testosterone on an isolated rat heart to demonstrate acute and possibly nongenomic effects of the steroid. Our results show that testosterone blocked the adenosine vasodilator effect and increased vascular resistance, even when its presence was restricted to the coronary vascular lumen. These effects were exerted rapidly and possibly through nongenomic mechanisms.     

Carcinoma of the uterine cervix. II. Lack of impact of prolongation of overall treatment time on morbidity of radiation therapy

PURPOSE: Several reports document a negative impact of prolongation of overall treatment time in a course of irradiation on tumor control and survival. A correlation has been documented of incidence of significant treatment sequelae with increasing doses of irradiation, volume of the specific organ, and dose per fraction. However, no data were found on the potential correlation of overall irradiation treatment time with significant sequelae. METHODS AND MATERIALS: Records were reviewed of 1,269 patients with carcinoma of the cervix (Stage IB to HI) treated with definitive irradiation (combination of external beam and two intracavitary insertions). Follow-up was obtained in 97% of patients (median, 12 years; minimum, 3 years; maximum, 28 years). The relationships between overall treatment time and time of brachytherapy and incidence of treatment sequelae were analyzed for each stage. RESULTS: Overall incidence of Grades 2 (moderate) sequelae was 7% and of Grade 3 (severe) sequelae, 11%. There was no significant correlation of various incidences of Grade 2 and 3 sequelae with overall treatment times (8% in patients treated in less than 7 weeks, 9% in 7.1 to 9 weeks, and 12% when treatment time was longer than 9 weeks) (p = 0.08). In patients with Stage IB and IIA tumors, incidence of rectal toxicity (mostly proctitis) was comparable in patients treated in less than 7 or 7.1 to 9 weeks (4.1 and 6%, respectively) and slightly higher in those treated in longer periods (11.5%) (p = 0.24). In patients with Stage IIB and III, the incidence of Grade 2 and 3 small bowel morbidity was 2% in those treated in less than 7 weeks, 6% for 7.1 to 9 weeks, and 4.9% for longer times (p < or = 0.01). This increased morbidity was also correlated with total dose of irradiation to the lateral pelvic wall: 5 of 257 (2%) for less than 60 Gy and 21 of 438 (4.8%) for higher doses (p < or = 0.01). There was no significant correlation between the timing of brachytherapy (usually two low dose rate intracavitary insertions performed within 4.5 to 6.5 weeks of initiation of external beam therapy) and significant treatment sequelae. CONCLUSIONS: We observed a varied average incidence of Grade 2 and 3 morbidity in the bladder, rectum, and small intestine with different overall treatment times, without a definite pattern to suggest an impact of prolongation of treatment time on morbidity. Likewise, there was no significant correlation with the timing of intracavitary insertions and morbidity of therapy. Because prolongation of the overall treatment time has a well-documented detrimental effect on pelvic tumor control and survival in carcinoma of the cervix with no significant impact on morbidity, it is imperative to deliver radiation therapy in the shortest possible time and without schedule interruptions.     

The significance ofheregulin in breast cancer tumor progression and drug resistance

Summary TheerbB-2 receptor plays an important role in the prognosis of breast cancer and is expressed at high levels in nearly 30% of tumors in breast cancer patients. While evidence accumulates to support the relationship betweenerbB-2 overexpression and poor overall survival in human breast cancer, understanding of the biological consequence(s) oferbB-2 overexpression remains elusive. The discovery ofheregulin has allowed us to identify a number of related but distinct biological endpoints which appear responsive to signal transduction through theerbB-2/4 receptor. These endpoints of growth, invasiveness, and differentiation have clear implications for the emergence, maintenance, and/or control of malignancy, and represent established endpoints in the assessment of malignant progression in human breast cancer. Preliminary studiesin vitro have shown thatheregulin induces a biphasic growth effect on cells witherbB-2 overexpression. Interestingly, we observed that expression ofheregulin correlates with a more aggressive/invasive, vimentin-positive phenotype in breast cancer cells lines. Therefore, we have postulated thatheregulin is involved in breast cancer tumor progression. We have shown thatheregulin inducesin vitro chemoinvasion and chemotaxis of breast cancer cells as well as growth in an anchorage dependent and independent manner. Interestingly, aheregulin neutralizing antibody inhibits chemotaxis and results in cell growth inhibition and blockade of the invasive phenotype. Strikingly, genetically engineered cells which constitutively expressheregulin demonstrate critical phenotypic changes that are associated with a more aggressive phenotype. Specifically, these cells are no longer dependent on estrogen for growth and are resistant to tamoxifenin vitro andin vivo, and moreover these cells metastasize to lymph nodes in athymic nude mice. These tumors appear to have lostbcl-2 expression as compared with the control tumors. In addition, presumably by activation/regulation of topoisomerase II, theheregulin-transfected cells become exquisitely sensitive to doxorubicin and VP-16. Clearly, mechanistic aspects of theerbB-2/4 andheregulin interaction need to be understood from a therapeutic standpoint which could provide additional insights into synergistic treatments for certain patients, or improve treatment regimens for a large number of women. The study ofheregulin and its co-expression witherbB-2/4 receptor and the assessment of its involvement in the progression from the in situ stage of breast tumors to the invasive one will additionally increase the relevance ofheregulin as a prognostic/diagnostic factor. We believe that our studies provide new insights into breast cancer diagnosis, prognosis, and treatment.Presented at the symposium "New Approaches in the Therapy of Breast Cancer", Georgetown University Medical Center, Washington DC, October 1994, generously supported by an education grant from Bristol-Myers Squibb.     

Blood conservation techniques for cardiac surgery: a survey of French centres

A survey resulting from a partnership between CECEC (Centre d'Etudes en Circulation Extra-Corporelle) and Laboratoires Hoechst, France was carried out amongst all French adult cardiac surgery centres. The aim of this study was to investigate the various strategies used to decrease blood loss during open-heart surgery. Due to an exceptionally high response rate, we are able to report the current practice of French cardiac centres which account for 75% of open-heart adult surgery. The three most interesting strategies for blood conservation appear to be haemodilution, blood salvage from the extracorporeal circuit and previously deposited autologous blood transfusion, yet the three methods which are predominantly used are haemodilution (92.7%), aprotinin therapy (87.8%) and blood salvage from the extracorporeal circuit (82.9%).     

Treatment of small cell lung cancer with a combination of VP16-213 and cyclophosphamide with cisplatin or radiotherapy

Summary Fifty five patients with small cell lung cancer were treated with a VP16-213 combination chemotherapy regimen in two consectutive series. The first series included 24 patients; 10 with limited and 14 with extensive disease were treated with VP16-213, 120 mg/m² p.o. daily for 5 consecutive days, Cyclophosphamide 600 mg/m² i.v. and Cisplatin 80 mg/m² i.v. with hydratation and manitol induced diuresis. The cycle was repeated every 3 weeks. The second series included 31 similar patients, 16 limited, and 15 extensive disease, treated with VP16-213 at the same dose and Cyclophosphamide at 1,200 mg/m² i.v. also repeated every 3 weeks; after three cycles the patients were treated with radiotherapy to the primary tumor and regional lymph nodes with 4,000 rads in a split course of three weeks interval, followed by the same combination chemotherapy. Response rate was 75% for the first series with 6 of 24 (25%) of complete responses in four limited and two extensive disease and a median survival time of 24 weeks. In the second series of patients there were 26 of 31 (83.8%) responses with 10 of 31 (32%) complete responses in nine limited and one extensive disease and a median survival time of 33 weeks for responders. Duration of response for complete responders was 36.8 weeks for the first series and 51 weeks for the second. Toxicity was mild and includes nausea and vomiting, myelosupression, alopecia in both series, with one toxic death in the second series.Both regimens are active with a low complete response rate, which was increased in the second series by the addition of radiotherapy, which did not increase overall survival. Send offprint requests to H. Cortés Funes, Section Oncologia Medica, Servicio de Radioterapia y Oncologia     

Abnormalities of cAMP signaling in affective disorders: implication for pathophysiology and treatment

Objective: During the last decade, much attention has been given to the role of signal transduction pathways in affective disorders. This review describes the possible role of the cAMP signaling in such disorders.

Methods: Among the components of cAMP signaling, this review focuses on the cAMP-dependent phosphorylation system. We analyzed the basic components of the cAMP-dependent phosphorylation system and the preclinical evidence supporting their involvement in the biochemical action of antidepressants and mood stabilizers. The clinical data available until now, concerning the possible link between the cAMP-dependent phosphorylation system and the pathophysiology of affective disorders, are also reviewed.

Results: The studies herein presented demonstrated that the levels and the activity of cAMP-dependent protein kinase are altered by antidepressants and mood stabilizers. Furthermore, these medications are able to modify the phosphorylation state, as well as the levels of some of the cAMP-dependent protein kinase substrates. More recently, clinical studies have reported abnormalities in the cAMP-dependent phosphorylation system in both peripheral cells and the postmortem brain of patients with affective disorders.

Conclusions: Overall, these studies support an involvement of cAMP signaling in affective disorders. The precise knowledge of the findings has the potential to improve the understanding of pharmacotherapy and to provide directions for the development of novel biochemical and genetic research strategies on the pathogenesis of affective disorders.