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Biomedical subjects

M Vigier

Publications and source records attributed to M Vigier.

At least 19 recordsLinked to original sources

High-dose imatinib mesylate combined with vincristine and dexamethasone (DIV regimen) as induction therapy in patients with resistant Philadelphia-positive acute lymphoblastic leukemia and lymphoid blast crisis of chronic myeloid leukemia.

Imatinib combined with high-dose chemotherapy is now becoming the gold standard for treatment of Philadelphia chromosome-positive acute leukemias. However, in all studies imatinib dosage was tapered to 400-600 mg per day. We decided to initiate a clinical trial to evaluate an opposite strategy based on high-dose imatinib (800 mg per day) combined with a less intensive chemotherapeutic regimen (vincristine and dexamethasone), which we called the DIV induction regimen. Thirty-one patients (18 relapsing or refractory Ph+ acute lymphoblastic leukemias and 13 lymphoid blast crisis chronic myelogenous leukemias) were enrolled. Complete remission (CR) was obtained in 28 out of 30 assessable patients. The median bcr-abl/abl ratio after the induction course was 0.1%. Median time to neutrophil recovery was 21 days. Fungus infections were observed in six patients out of 31 and possibly related to dexamethasone. Neuropathy due to vincristine was noted in 14 cases. Nine out of 19 patients under 55 years received allogenic stem cell transplantation after a median time of 78 days post-CR. Patients older than 55 years experienced a 90% CR rate without additional toxicities, suggesting the DIV regimen may also be proposed as a front line therapy in older patients.

Antineoplastic Combined Chemotherapy Protocols↗

Report of 34 patients with clonal chromosomal abnormalities in Philadelphia-negative cells during imatinib treatment of Philadelphia-positive chronic myeloid leukemia.

Imatinib mesylate (Gleevec), an inhibitor of the BCR-ABL tyrosine kinase, was introduced recently into the therapy of chronic myeloid leukemia (CML). Several cases of emergence of clonal chromosomal abnormalities after therapy with imatinib have been reported, but their incidence, etiology and prognosis remain to be clarified. We report here a large series of 34 CML patients treated with imatinib who developed Philadelphia (Ph)-negative clones. Among 1001 patients with Ph-positive CML treated with imatinib, 34 (3.4%) developed clonal chromosomal abnormalities in Ph-negative cells. Three patients were treated with imatinib up-front. The most common cytogenetic abnormalities were trisomy 8 and monosomy 7 in twelve and seven patients, respectively. In 15 patients, fluorescent in situ hybridization with specific probes was performed in materials archived before the initiation of imatinib. The Ph-negative clone was related to previous therapy in three patients, and represented a minor pre-existing clone that expanded after the eradication of Ph-positive cells with imatinib in two others. However, in 11 patients, the new clonal chromosomal abnormalities were not detected and imatinib may have had a direct effect. No myelodysplasia was found in our cohort. With a median follow-up of 24 months, one patient showed CML acceleration and two relapsed.

Adult↗

The effects of FSH and of testosterone on the completion of meiosis and the very early steps of spermiogenesis of the rat: an in vitro study.

The role of FSH and of testosterone in spermatogenesis has been a matter of controversy. In the present study, we addressed the involvement of these hormones in the regulation of the completion of meiosis of male rats under in vitro conditions. In the first series of experiments, middle/late pachytene spermatocytes were cocultured with Sertoli cells for 2 weeks in the absence or presence of FSH and/or testosterone. Treatment with both FSH and testosterone reduced slightly the percentage of apoptotic germinal cells in the cultures. Moreover, the number of round spermatids formed in vitro was enhanced by FSH or testosterone when compared with control cultures. Neither hormone influenced the half-life of round spermatids under the present culture conditions. The amounts of TP1 mRNAs in FSH- or FSH plus testosterone-treated cultures were higher than those of controls. In another series of experiments, round spermatids were incubated for 24 h in media conditioned by Sertoli cells cultured in the absence or presence of FSH and/or testosterone. TP1 mRNA contents of round spermatids incubated in media from Sertoli cells cultured in the presence of FSH and/or testosterone were two- to threefold higher than those of spermatids incubated in media from Sertoli cells cultured without hormones. These results indicate that FSH and testosterone have positive and somewhat overlapping effects on the meiotic divisions and the post-meiotic expression of a germ cell-specific gene, effects which cannot be related solely to their ability to reduce germinal cell apoptosis. Use of this culture system should help to test the effect of any hormone or factor on those steps in order to understand better their regulation.

Animals↗

PCR detection of residual Bcl-2/IgH-positive cells after high-dose therapy with autologous stem cell transplantation is a prognostic factor for event-free survival in patients with low-grade follicular non-Hodgkin's lymphoma.

This study was designed to evaluate the results of high-dose therapy followed by purged autologous stem cell transplantation (ASCT) for patients with low-grade follicular non Hodgkin's lymphoma (LGFL), and the prognostic significance of PCR detection of residual Bcl-2/IgH-positive cells after ASCT. Between 1992 and 1998, 49 patients with LGFL received total body irradiation and high-dose cyclophosphamide followed by purged ASCT. PCR amplification of the Bcl-2/IgH rearrangement was performed at diagnosis, on stem cell collections before and after purging and on bone marrow and blood samples after ASCT. With a median follow-up of 76 months (37-103) 34 patients remain alive and event-free. A total of 20 patients had disease recurrence, three patients developed secondary myelodysplastic syndrome (MDS). In all, 11 patients died; 10 deaths were because of recurrent disease, one because of MDS. Kaplan-Meier estimates of event-free survival (EFS) and overall survival (OS) at 5 years were 65% (+/-7%) and 77% (+/-6%), respectively. Patients who achieved a sustained molecular complete response (CR) had a lower risk of disease recurrence and experienced significantly longer EFS (93% (+/-6%) vs 11% (+/-7%) P=0.0008) and OS (100 vs 55% (+/-12%) P=0.0057). In conclusion, myeloablative therapy followed by purged ASCT may induce long EFS in patients with LGFL. The achievement of sustained molecular CR after ASCT improves EFS and OS.

Adult↗

Front-line high-dose therapy with autologous stem cell transplantation for high risk Hodgkin's disease: comparison with combined-modality therapy.

This retrospective study compares high-dose therapy (HDT) with autologous stem cell transplantation and combined-modality treatment (CT) as a first-line therapy for Hodgkin's disease (HD) for patients with both a clinical stage (CS) IV and/or a mediastinal mass > or =0.45 of the thoracic diameter (MM > or =0.45) at diagnosis, and an incomplete response after the first-line chemotherapy. Data on 42 grafted patients (GP) in Nantes Hospital, France and on 108 combined-modality treated patients (CTP) from two protocols of the GOELAMS group, France (POF 81 and H90) was analyzed. Both groups were comparable except for pulmonary disease in excess in the grafted group (P = 0.01). Among GP, 95% were in complete response at the end of first-line treatment and 77% among CTP. Median follow-up was 53 months (range, 7 to 128 months) for GP and 88 months (range, 25 to 181 months) for CTP. The 5-year freedom from progression (FFP) and event-free survival (EFS) rates were better for GP (87% vs 55% for FFP: P = 0.0004 and 81% vs 51% for EFS: P = 0.0004) whereas the overall survival (OS) rates did not differ significantly (85% for GP vs 71% for CTP: P = 0.06). Similar results were obtained for the groups with a response > or =50% after initial chemotherapy: 91% vs 65% for FFP, P = 0.01; 87% vs 61% for EFS, P = 0.02; and 92% vs 77% for OS, P = 0.2; and for the groups with a response <50%: 80% vs 22% for FFP, P = 0.0003; 72% vs 13% for EFS, P = 0.0001; and 76% vs 46% for OS, P = 0.04. This study shows a better control of the disease with HDT.

Adolescent↗

Long-term results (12 years) of high-dose therapy in 127 patients with de novo multiple myeloma.

This report describes the long-term outcome of a cohort of 127 de novo multiple myeloma patients treated with at least one course of high-dose therapy (HDT) in a single institution between June 1985 and December 1995, for whom the minimum follow-up duration for survivors is 6 years. The 12-year overall survival (OS) and event-free survival (EFS) rates are 24.9% and 3.1%, respectively, and the median survival and EFS are 49 and 17 months, respectively. Only four patients are alive and disease-free 79, 90, 132 and 153 after the first HDT, respectively. Three of them received a subsequent allogeneic bone marrow transplantation. Three factors significantly influence OS in this series: B2M at diagnosis, age, and the completion of a second HDT. The 10-year survival is 18.9% for the group of patients with B2M level >3 mg/l at diagnosis as compared with 41% for patients with B2M < or =3, with a median survival of 31 months vs 73 (P = 0.01). The 10-year survival is 23.4% for the group of patients aged >55 years as compared with 36.5% for patients aged <55 years, with a median survival of 34.5 months vs 70.5 (P = 0.04). The 10-year survival is 20.4% for the group of patients who did not receive a second HDT as compared with 35.2% for patients who completed a second HDT, with a median survival of 29 months vs 70 (P = 0.02). In this study we show that some patients treated with HDT experience durable remission and prolonged survival. This survival is significantly influenced by age (< or =55 years), B2M at diagnosis (< or =3 mg/l) and by the completion of two cycles of HDT.

Adult↗

Longitudinal study of bacterial, viral, and fungal infections in adult recipients of bone marrow transplants.

The epidemiology of infections was studied in a retrospective cohort of 446 recipients of bone marrow transplants (BMTs; 92 of which were allogeneic and 354 of which were autologous) during 1993--1996. Infections that were microbiologically documented in 274 recipients included bacteremia, urinary tract infections, cytomegalovirus viremia, fungemia, invasive aspergillosis, and catheter-related infections. During the period of neutropenia, no differences were found between recipients of allogeneic BMTs and recipients of autologous BMTs with regard to the incidence and the nature of infection. After patients underwent engraftment, bacteremia, cytomegalovirus viremia, and invasive aspergillosis were significantly more common in recipients of allogeneic BMTs than in recipients of autologous BMTs. Deaths caused by infection were uncommon and were mainly the result of invasive aspergillosis. Therefore, empirical antimicrobial therapy should be the same for recipients of both allogeneic and autologous BMTs during the period of neutropenia; after engraftment, more attention should be paid to the risk of infection in allogeneic BMT recipients, particularly with regard to detection and prevention of invasive aspergillosis.

Adolescent↗

Meiotic differentiation of germinal cells in three-week cultures of whole cell population from rat seminiferous tubules.

The aim of the present study was to set up a culture system allowing most of the meiotic phase of rat spermatogenesis to occur in vitro. For that purpose, the differentiation of spermatogenic cells was monitored by three criteria: 1) examination of expression of genes specifically expressed at a high level in pachytene spermatocytes (the phosphoprotein p19 [p19] and the testis-specific histone TH2B) or in round spermatids (transition protein 1 [TP1] and transition protein 2 [TP2]) by reverse transcription-polymerase chain reaction (RT-PCR); 2) ploidy analysis; and 3) cytological and immunocytochemical study of the germ cells. In the first trial, we determined the changes in the ratios of p19:TP1 and TH2B:TP2 mRNA-related PCR products in the whole testis of rats between 18 and 60 days postpartum and related those results to the sequential appearance of the various types of spermatogenic cells during that period. In the second trial, our aim was to reproduce, in a culture system using seminiferous tubules from 23- to 25-day-old rats, the changes observed in vivo. The p19:TP1 and TH2B:TP2 ratios decreased dramatically in testicular extracts of rats between 32 and 40 days postpartum, i.e., at the time period during which round spermatids become more and more numerous in the testis. When seminiferous tubules were seeded in bicameral chambers, cell viability remained close to 70% of total cells throughout the 3-wk culture period. Both p19:TP1 and TH2B:TP2 ratios decreased during the first week of culture. This was attributable to a decrease in the levels of p19 and TH2B mRNAs and also to an enhancement in the relative amounts of TP1 and TP2. These changes were correlated with the appearance of a 1C cell population in the culture. Histological examination of the culture demonstrated that under the conditions of the present study, 5-bromo-2'-deoxyuridine-labeled pachytene spermatocytes of stages IV-VI were able to differentiate into secondary spermatocytes, then into round spermatids.

Animals↗

Sertoli cell-germ cell interactions and TGF beta 1 expression and secretion in vitro.

Transforming growth factor beta 1 (TGF beta 1) has been reported to be secreted and to act within the somatic cells of the testis. We examined whether the TGF beta 1 expression is present at mRNA and protein levels in purified rat Sertoli cells (SC), purified pachytene spermatocytes (SPC), and early spermatids (SPT) cultured alone or together. SC expressed a single TGF beta 1 transcript of 2.5 kb, but no TGF beta 1 protein could be detected in SC conditioned medium indicating that, if at all, SC secreted less than 10 pg/10(6) cells/24 h. Neither TGF beta 1 mRNA nor protein could be detected in either SPC or SPT. Coculture of SC with either SPC or SPT resulted in a 2-fold increase of TGF beta 1 mRNA and more importantly in the secretion of TGF beta 1 protein. These findings demonstrate that Sertoli cell-germ cell interactions regulate TGF beta 1 expression and secretion and indicate that TGF beta 1 may be involved in spermatogenesis.

Animals↗

Comparative genomic hybridization detects genomic abnormalities in 80% of follicular lymphomas.

Comparative genomic hybridization (CGH) was used to analyse 34 follicular lymphoma (FL) samples. 27 samples showed DNA sequence copy number changes of at least one genomic region (26 samples with at least one gain and nine with at least one loss). Some chromosomes or chromosomal regions were preferentially involved. The most frequently gained regions were chromosome 18q (29% of samples), chromosome X (21%), chromosome 7 (18%), chromosomes 2, 6p and 8q (12%). Two regions were preferentially lost: 6q (12%) and 17p (9%). All these gained and lost regions have been previously reported in cytogenetic studies, confirming the accuracy of CGH in detecting genetic abnormalities in FL. 21% of samples displayed normal profiles, probably reflecting the absence of unbalanced abnormality, which is also in agreement with the cytogenetic data. In conclusion, we showed that CGH is an accurate, reliable and rapid method and we propose the inclusion of CGH in the evaluation of FL at diagnosis.

Chromosome Aberrations↗

Pre- and postmeiotic expression of male germ cell-specific genes throughout 2-week cocultures of rat germinal and Sertoli cells.

The present study was aimed at examining, by reverse transcription polymerase chain reaction, the expression of germ cell-specific genes in cocultures of Sertoli cells with either pachytene spermatocytes (PS) or round spermatids (RS). In situ hybridization studies showed that the mRNAs encoding phosphoprotein p19 and the testis-specific histone TH2B were specifically expressed in PS whereas those encoding the transition proteins TP1 and TP2 were specific to RS. This resulted in p19:TP1 and TH2B:TP2 ratios that were much higher in PS fractions than in RS fractions prepared by elutriation. When PS or RS were seeded on Sertoli cell monolayers in bicameral chambers, both the number and the viability of the cells decreased during the coculture. However, both parameters were equal to, or higher than, 60% after 2 wk. In PS-Sertoli cell cocultures, the ratios of p19:TP1 and TH2B:TP2 decreased dramatically during the second week of culture; this was due not only to a decrease in the levels of p19 and TH2B mRNAs but also to an enhancement in the relative amounts of TP1 and TP2 as compared to the amounts present on the first day of the coculture. Conversely, both ratios remained low in RS-Sertoli cell cocultures; this was due to a decrease in the levels of the four mRNAs studied during the coculture period. DNA flow cytometry studies showed the occurrence of a haploid cell population (1C) in PS-Sertoli cell cocultures from Day 2 onward, together with a decrease in the tetraploid cell population (4C). No such changes were observed in Sertoli cell-only cultures. By contrast, the haploid population decreased 3-fold during the first week in RS-Sertoli cell cocultures. Immunocytochemical studies demonstrated further that 5-bromo-2'-deoxyuridine-labeled PS of stages V-VIII were able to differentiate into RS under the present coculture conditions. Hence, although clearly imperfect, the present coculture system should help to clarify the local regulations governing spermatogenesis and should allow easier study of spermatogenic cell gene expression.

Animals↗

Transcription and post-transcriptional regulation of luteotropin/chorionic gonadotropin receptor by the agonist in Leydig cells.

Porcine Leydig, cultured in a chemically defined medium, express luteotropin/human chorionic gonadotropin (LH/hCG) receptor and mRNA transcripts of several sizes (7.6, 6.7, 5.6, 4.7, 4, 2.6 and 1.4 kb). Incubation of these cells with hCG results in a concentration-dependent decrease of both LH/hCG receptor number and of all mRNA transcripts with a half-maximal at 0.01 nM. Time-course analysis of the effects of maximal (1 nM) concentration of hCG on both receptor number and mRNA levels results in a lag period of about 6-8 h. Thereafter, the receptor number progressively declines to reach a low point (20% of control) at 36 h, whereas more than 80% of receptor mRNA were lost between 8-12 h after addition of the hormone. By nuclear run-on assays, we showed that hCG caused a slight reduction (13 +/- 2%) in LH/hCG receptor gene transcription, which could not explain the rapid and pronounced mRNA decline observed between 8-12 h. In fact, we estimated that hCG reduced 10-fold (from < 22 h to 2 h) the half-life of LH/hCG receptor mRNA. Both actinomycin D and cycloheximide blocked the hCG-induced decrease in both receptor number and mRNA levels. These results indicate that the main mechanism by which hCG regulates its own receptor is by inducing a decrease in the stability of its own receptor mRNA and this effect requires induction of transcription and translation, presumably leading to synthesis of a labile factor(s) which favors the degradation of LH/hCG mRNA. Most of the effects of hCG are mediated by cAMP since treatment of cells with its 8-bromo derivative leads to a similar reduction in the level of LH/hCG receptor and mRNA. Finally, the effects of hCG are reversible, since after withdrawal of the hormone there was a recovery of receptor mRNA followed by receptor number.

Animals↗

Immunohistochemical localization of transforming growth factor-beta 1 in the fetal and neonatal rat testis.

The localization of transforming growth factor-beta 1 in the fetal and neonatal rat testis (from day 13.5 of fetal life to postnatal day 20) was investigated by an immunohistochemical staining method employing a polyclonal anti-TGF-beta 1 antibody that does not cross react with either TGF-beta 2 or TGF-beta 3. In testis and mesonephros tissue, immunostaining for TGF-beta 1 was undetectable on fetal day 13.5 and appeared exclusively in the primordial Sertoli cells on fetal day 14.5. Staining in Sertoli cells was still clearly observed on days 15.5 and 16.5 of fetal life and became faint from fetal day 18.5 onwards. In fetal Leydig cells, a positive reaction for TGF-beta 1 appeared on day 16.5 and became very intense during late fetal life. After birth, fetal-type Leydig cells, which were still observed on postnatal days 4 and 20, also exhibited a very strong immunostaining for TGF-beta 1, whereas adult-type Leydig cells, observed on day 20, showed a slight staining. No immunoreactivity for TGF-beta 1 was found in germ cells and peritubular cells on any day studied. In conclusion, TGF-beta 1 is present very early in the fetal rat testis and its prevailing localization shows age-related changes, which suggests that this factor plays an autocrine/paracrine role in the regulation of testicular function and differentiation, during early development.

Animals↗

Expression and regulation of transforming growth factor-beta 1 messenger ribonucleic acid and protein in cultured porcine Leydig and Sertoli cells.

In the present work, the expression and secretion of transforming growth factor-beta 1 (TGF beta 1) by immature pig Leydig and Sertoli cells were investigated. Both cell types express two TGF beta 1 mRNA transcripts of 2.5 and 3.5 kilobases, and the levels were 2.6-fold higher in Leydig than in Sertoli cells. In the latter cells, mRNA levels were enhanced when cultured cells were stimulated by epidermal growth factor and phorbol ester (4-beta-phorbol 12-myristate 13-acetate) and significantly decreased by FSH and testosterone. Using a polyclonal antibody raised against a synthetic peptide that corresponded to the carboxyl-terminal region of TGF beta 1 and recognized this peptide, but not TGF beta 2 or TGF beta 3, specific immunostaining of both Leydig and Sertoli cells was demonstrated in situ, after cell isolation, and during culture. The immunostaining was more marked in Leydig cells than in Sertoli cells. Western blot analysis of Leydig or Sertoli cell-conditioned medium demonstrated a band of 25 kilodaltons, which was shifted to 12.5 kilodaltons under reducing conditions. Using the mink lung epithelial cell bioassay for TGF beta 1, we could demonstrate the presence of TGF beta 1-like activity in Leydig and Sertoli cell-conditioned media after acid treatment, but not before activation. The inhibitory effects of both pure TGF beta 1 and acidified conditioned medium were almost completely blunted by the TGF beta 1 antibody. The amounts of TGF beta 1 secreted by Sertoli and Leydig cells were not significantly different and varied between 400-800 pg/48 h.10(6) cells. These studies demonstrate for the first time that both pig Leydig and Sertoli cells express TGF beta 1 mRNA, and the TGF beta 1-like activity secreted by these cells corresponds to TGF beta 1. As TGF beta 1 has been demonstrated to have strong effects on testicular cells, in particular on Leydig cell functions, it is suggested that local secreted TGF beta 1 may play a role in the autocrine/paracrine regulation of testicular functions.

Animals↗

Possible involvement of transforming growth factor-beta in the inhibition of rat pituitary tumor growth by estradiol.

We have shown that growth of F4Z2 cells and F4Z2 tumors was stimulated by estradiol, that of MtTF4 and F4P tumors was inhibited and that of F4P cells remained insensitive. In the present work we explore the possible role of transforming growth factor-beta (TGF-beta) as a mediator of estradiol action in these pituitary tumors and cell lines. In vivo, estradiol treatment increased the concentration of TGF-beta 1 mRNAs in tumors whose growth was inhibited by estradiol (MtTF4 and F4P) but not in tumors whose growth was stimulated (F4Z2). F4Z2 and F4P cell lines also contained TGF-beta 1 transcripts. These cells and tumors differed by two points: the level of TGF-beta 1 transcript was higher in F4Z2 than in F4P cells while the opposite situation was observed in vivo and the concentration of TGF-beta 1 mRNA in cultured cells was insensitive to estradiol (1 or 100 x 10(-9) M). Moreover, the secretion of TGF-beta like activity assayed by two different methods was estradiol insensitive and the growth of both cell lines was dose-dependently inhibited by TGF-beta 1 (ED50:2 x 10(-11) M). Since estradiol increases TGF-beta 1 mRNA in the tumors MtTF4 and F4P whose growth is inhibited by estradiol and that TGF-beta 1 inhibits the proliferation of F4P cells it is proposed as a working hypothesis that TGF-beta 1 is one of the mediators of the inhibitory effect of estradiol in pituitary tumors. No data favor the hypothesis that estradiol stimulates pituitary tumor proliferation by decreasing TGF-beta production.

Animals↗

Opposite vectorial secretion of insulin-like growth factor I and its binding proteins by pig Sertoli cells cultured in the bicameral chamber system.

A two-chamber system has been employed to investigate the vectorial secretion of insulin-like growth factor I (IGF-I) and its binding proteins (IGF-BPs) by pig Sertoli cells. The kinetics of transport of [3H]insulin as well as the transepithelial electrical resistance of filters coated with reconstituted basement membrane, in the absence of presence of Sertoli cells, indicated the formation of a functional barrier by Sertoli cells. The rates of diffusion of [125I]IGF-I or [125I]human CG were slower from the apical (AC) to the basal (BC) compartment than in the opposite direction. However, the IGF-I content and concentration in the BC was twice that seen in the AC. FSH increased the secretion of IGF-I in the BC, and therefore increased the BC/AC ratio. In contrast, most of the IGF-BPs, with apparent molecular sizes of 39-43, 34, 29 and 24 kDa, were secreted in the AC. FSH increased the secretion of IGF-BP 39-43 kDa (BP3). This is the first report of opposite vectorial secretion of IGF-I and its binding protein by any cell type.

Animals↗

Regulation by growth factors of Leydig cell differentiated functions.

In this paper the effects of growth factors on the differentiated function of pig Leydig cells and other steroidogenic cells are reviewed. Two types of action have been observed, i.e. positive or negative acute effects on testosterone secretion, and long-term trophic effects of hCG receptor and responsiveness to hCG. Among the growth factors, insulin-like growth factor I (IGF-I) and transforming growth factor beta (TGF beta-1) are of particular interest. IGF-I is required for the maintenance and probably the expression of differentiated functions of several steroidogenic cells, including the Leydig cells. TGF beta-1 has effects opposite to IGF-I on Leydig cell functions. When considering effects of growth factors on Leydig cells, caution should be taken in extrapolating results obtained in one species to another.

Animals↗