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A Calender

Publications and source records attributed to A Calender.

At least 55 records · Page 3Linked to original sources
PubMed1997

[Ethical recommendations for the genetic screening of hereditary endocrine diseases].

Predisposition to inherited diseases has been extensively studied over the last few years. Genetic studies have created a major concern about the psychological and ethical impact of risk evaluation in predisposed families. A significant number of inherited endocrine diseases are late-onset diseases and genetic risk assessment using molecular genetics leads to more accurate clinical and therapeutic follow-up of gene carriers. We describe minimal recommendations which could be associated to the official French laws published in July 1994 and analyze their concrete applications in clinical and genetic follow-up of patients and kindreds defined as gene carriers in predisposed families.

Bioethics↗
PubMed1996

Definition of the minimal MEN1 candidate area based on a 5-Mb integrated map of proximal 11q13. The European Consortium on Men1, (GENEM 1; Groupe d'Etude des Néoplasies Endocriniennes Multiples de type 1).

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disorder with a high penetrance characterized by tumors of the parathyroid glands, the endocrine pancreas, and the anterior pituitary. The MEN1 gene, a putative tumor suppressor gene, has been mapped to a 3- to 8-cM region in chromosome 11q13 but it remains elusive as yet. We have combined the efforts and resources from four laboratories to form the European Consortium on MEN1 with the aims of establishing the genetic and the physical maps of 11q13 and of further narrowing the MEN1 region. A 5-Mb integrated map of the region was established by fluorescence in situ hybridization on both metaphase chromosomes and DNA fibers, by hybridization to DNA from somatic cell hybrids containing various parts of human chromosome 11, by long-range restriction mapping, and by characterization of YACs and cosmids. Polymorphic markers were positioned and ordered by physical mapping and genetic linkage in 86 MEN1 families with 452 affected individuals. Two critical recombinants identified in two affected cases placed the MEN1 gene in an approximately 2-Mb region around PYGM, flanked by D11S1883 and D11S449.

Animals↗
PubMed1996

Definition of the Minimal MEN1 Candidate Area Based on a 5-Mb Integrated Map of Proximal 11q13

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disorder with a high penetrance characterized by tumors of the parathyroid glands, the endocrine pancreas, and the anterior pituitary. The MEN1 gene, a putative tumor suppressor gene, has been mapped to a 3- to 8-cM region in chromosome 11q13 but it remains elusive as yet. We have combined the efforts and resources from four laboratories to form the European Consortium on MEN1 with the aims of establishing the genetic and the physical maps of 11q13 and of further narrowing the MEN1 region. A 5-Mb integrated map of the region was established by fluorescence in situ hybridization on both metaphase chromosomes and DNA fibers, by hybridization to DNA from somatic cell hybrids containing various parts of human chromosome 11, by long-range restriction mapping, and by characterization of YACs and cosmids. Polymorphic markers were positioned and ordered by physical mapping and genetic linkage in 86 MEN1 families with 452 affected individuals. Two critical recombinants identified in two affected cases placed the MEN1 gene in an approximately 2-Mb region around PYGM, flanked by D11S1883 and D11S449.

Journal Article↗
PubMed1996

[Clinical and genetic study of a familial case of multiple endocrine neoplasia type 1 (MEN 1). From value of multidisciplinary collaboration].

Multiple Endocrine Neoplasia type 1 (MEN 1) is an autosomal dominant familial syndrome characterized by involvement of several endocrine glands, including parathyroid, pancreatic islet cells, anterior pituitary and diffuse neuroendocrine tissues (carcinoids). The gene causing this syndrome has been localized to chromosome 11 but was not cloned up-to-date. Pre-clinical diagnosis in predisposed MEN 1 families was based on the use of genetic linkage analysis with polymorphic DNA probes flanking the disease locus. The set-up collaborative multi-disciplinar medical and surgical network facilitates further clinical and genetic studies on MEN 1 families. Semiological course of the disease is complex and the main objective in clinical follow-up of patients and related is to limit the probability of misdiagnosis. The present report describe the clinical and genetic analysis in a MEN 1 family and the difficulties related to diagnose the disease. An interesting observation on two cases of hyperprolactinemia by two individuals further excluded by genetic analysis assess the potential risk of bias in genetic linkage studies in non-well documented families. Concerted analysis of genetic and bio-clinical data permitted the evaluation of each patient and to exclude the risk of MEN 1 in all children tested. This example demonstrates the need of a complete clinical information previously to genetic analysis and a multi-disciplinar and collaborative approach in follow-up of patients in each family.

Adolescent↗
PubMed1995

[Hereditary multiple endocrine neoplasia. New genetic data and clinical applications in type 1 multiple endocrine neoplasia].

Multiple endocrine neoplasia (MEN) is a group of characteristic affections involving benign or malignant secreting tumours of several endocrine glands. Recent progress in genetic mapping has led to the precise localization of the genes causing these familial diseases. This technique provides new means of diagnosis greatly improving conventional diagnostic methods. In type 1 MEN, laboratory tests are directed to identifying the target gland and its effect on hormone status. Imaging techniques including echography, CT scan, magnetic resonance imaging, echoendoscopy and scintigraphy add further information. The molecular genetics approach is an indirect one based on a family study. Blood samples must be obtained from at least two certain probands and at least two healthy members of the family. By mapping the genes with precise genetic probes, the morbid haplotype could be identified and used to predict the risk of morbidity in the descendance. The GENEM 1 (Groupe d'Etudes sur les Néoplasies endocriniennes multiples de type 1) is a multidisciplinary collaboration between endocrine surgeons, endocrinologists, gastroenterologists, geneticians, pathologists and biologists working towards identifying the causal gene and better understand the pathophysiology of these tumours. We are undoubtedly on the threshold of this discovery which could help improve the diagnosis of this generally poorly recognized disease with an underestimated prevalence.

Humans↗
PubMed1995

Molecular tools for presymptomatic testing in multiple endocrine neoplasia type 1.

The aim of this workshop session was to define a set of molecular tools for pre-clinical diagnosis in affected families, and to assess presence or absence of linkage to 11q13 in families with classical MEN1 as well as with MEN1-related clinical features. A consensus linkage map of first- and second-choice markers based on PCR as well as Southern blotting was established at the workshop. Based on the results from linkage analysis in 87 families with classical MEN1, presymptomatic testing using the suggested panel of markers, can now be performed with great accuracy.

Acromegaly↗
PubMed1995

Multiple endocrine neoplasia type 1 in France: clinical and genetic studies.

Multiple endocrine neoplasia type 1 (MEN1) is a hereditary syndrome characterized by the involvement of several endocrine glands, including the parathyroid glands, the pancreatic islet cells, the anterior pituitary gland and other neuroendocrine tissues. In order to build up a French MEN1 register, a collaborative network was developed through the 'Groupe d'Etude des Néoplasies Endocriniennes Multiples de type 1' or GENEM 1. A 2-year follow-up in 40 medical and surgical units allowed the identification of more than 150 individual patients and 45 MEN1 families, and defined the major clinical features of the disease in our series. Multiple endocrine neoplasia type 1 is inherited as an autosomal dominant trait. The gene causing this syndrome has been localized to chromosome 11, band 11q13, and molecular genetic markers flanking the MEN1 locus are of use in identifying disease gene carriers in predisposed families. Selected data were presented in order to discuss the management of patients by combined clinical, biochemical and genetic screening. The set-up of a national register by a multi-disciplinary and collaborative medical and surgical network will facilitate further research on the clinical management of MEN1 patients and the basic physio-pathology of the disease.

Adolescent↗
PubMed1995

Familial acromegaly: a specific clinical entity--further evidence from the genetic study of a three-generation family.

Familial acromegaly is a very rare inherited disorder, characterized by the clustering within a single family of several related cases with somatotroph adenomas and acromegaly. The causes of these dominantly inherited pituitary tumours remain unknown. Although these families have a clinical presentation distinct from that of multiple endocrine neoplasia type 1 (MEN-1), the question of this syndrome as being linked to the MEN-1 locus has remained open. Our aim was to study a three-generation family with cases of acromegaly in a mother and her son, to explore better the clinical presentation of the disease, its pattern of inheritance and to test the hypothesis of a genetic linkage to the MEN-1 locus using closely linked polymorphic genetic markers. The refined analysis of 15 unaffected relatives revealed miscellaneous non-specific endocrine dysfunctions and the presence of multiple lipomata, as noted previously in some cases. Moreover, the notion of acromegalo-gigantism in the maternal grandmother and an incomplete penetrance appeared even more typical, suggesting that familial acromegaly is a specific clinical entity. Finally, under the hypotheses assumed for segregation analysis, no clinical, biological or genetic evidence of linkage to the MEN-1 locus could be retained in this family. However, these conclusions were limited because of incomplete penetrance and uncertain definition of the carrier status. Therefore, we conclude that further identification of the genetic predisposition to familial acromegaly might be obtained from the combined molecular genetic analysis of several families presenting with the same clinical features.

Acromegaly↗
PubMed1995

[Screening of multiple endocrine neoplasias type 1. Reflexions of the Study Group on Multiple Endocrine Neoplasias type 1].

The "Groupe d'Etude des Néoplasies Endocriniennes Multiples de type 1 (GENEM 1)" is a French group involved in a comprehensive multicentre study of Multiple Endocrine Neoplasia type 1 syndrome (NEM 1). The objectives of this group are to define diagnostic and therapeutic protocols and to carry out genetic research on NEM1. The first aim of physicians is to recognize the syndrome and to determine the appropriate screening especially into two circumstances: 1 degree In case of isolated and sporadic glandular disease -i-e-parathyroid glands, endocrine pancreas, antehypophysis, adrenal glands and neuroendocrine tumors? 2 degrees In case of very high probability of NEM 1 syndrome? This paper answers these two questions, based on the analysis of the first 150 cases collected by the GENEM 1.

Adenoma↗
PubMed1994

RET proto-oncogene mutations in French MEN 2A and FMTC families.

Constitutional mutations of the RET proto-oncogene have been identified in multiple endocrine neoplasia type 2A (MEN 2A), type 2B (MEN 2B) and familial medullary thyroid carcinoma (FMTC) families. We sequenced RET exons 10 and 11 in 86 unrelated patients with an inherited predisposition to MTC (excluding MEN 2B). Germ-line mutations were identified in 93% of the MEN 2A families and 67% of the FMTC families tested. All were missense mutations affecting one of three cysteines in the extracellular domain of the RET tyrosine kinase receptor. The prevalence of phaeochromocytoma and hyperparathyroidism was significantly higher in families with a mutation of cysteine 634. These data confirm the preferential localisation of MEN 2A and FMTC associated mutations and the strong correlation between clinical manifestations and the position of RET mutation. Although direct sequencing of RET exons 10 and 11 allows the identification of a constitutional mutation in a large proportion of MEN 2A and FMTC families, our data sustain the existence of other MTC predisposing mutations elsewhere in RET coding or regulating region.

Carcinoma, Medullary↗
PubMed1993

Epstein-Barr virus (EBV) nuclear-antigen-2-induced up-regulation of CD21 and CD23 molecules is dependent on a permissive cellular context.

The Epstein-Barr virus (EBV) induces unlimited growth of B lymphocytes in vitro, a phenomenon known as immortalization. The elucidation of the mechanisms by which EBV de-regulates B-cell proliferation in vitro will permit an understanding of how the virus contributes in vivo to the genesis of Burkitt's lymphoma (BL) and of lymphoproliferations in immunosuppressed patients. At present, no single EBV immortalizing gene has been identified, and the hypothesis has been made that many viral genes cooperate in establishing an autocrine loop of secretion leading to immortalization. Constitutive expression of B-cell surface molecules such as CD21 and CD23, specifically implicated in the control of B-cell proliferation, is indeed induced at the surface of immortalized B lymphocytes. The expression of the viral nuclear antigen 2 (EBNA2) has been shown to be in part responsible for CD21 and CD23 up-regulation, and EBNA2 is suspected to be a transactivator of cellular genes, although this point remains to be demonstrated. The role of EBNA2 gene, independently of other viral genes, has been investigated by transfection into B-lymphoma lines, but conflicting results have been reported. To further investigate its role in the regulation of CD21 and CD23 molecules, we have compared the effects of EBNA2 expression in 2 sets of B-lymphoma lines infected with P3HR1 EBV strain, and/or transfected with EBNA2 gene. We report here that: (i) EBNA2 expression is not a sufficient condition to induce CD21 and CD23 upregulation, EBNA2's effects are highly dependent on the cellular context, and moreover can be modified by infection with P3HR1 virus; (ii) EBNA2 induces activation of CD23 expression in a very particular way, namely, an increased quantity of CD23 steady-state RNA coding for the form A of the protein, which is not detectable at the cell surface but directly secreted.

Antigens, Viral↗
PubMed1993

Expression of the Epstein-Barr virus (EBV) latent membrane protein is tightly regulated, independently of EB nuclear antigen 2 and of EBV integration or copy number.

In vivo, Epstein-Barr virus (EBV) is associated with human tumours and with lymphoproliferations in immunosuppressed patients. In vitro, EBV induces unlimited growth of normal B-lymphocytes, a phenomenon known as immortalization. A limited number of viral genes is expressed during this phenomenon and their relative role concerning the deregulation of cellular proliferation is still unclear. At present, the nuclear antigen EBNA2 and the membrane protein LMP are the two EBV proteins considered to be implicated in the immortalization process. Moreover, many data support the hypothesis that EBNA2 is the major inducer of LMP expression by transactivation; however, in some instances, expression of the two proteins is not correlated, suggesting the existence of complex interactions between EBV and its host-cell that influence viral gene regulation. In an attempt to study thoroughly these EBNA2/LMP interactions, it is important to evaluate whether EBNA2 is or is not a major inducer of LMP expression, and which other parameters can influence LMP expression. By analysing two sets of B-lymphoma lines either infected in vitro with EBV or stably transfected with EBNA2, we have demonstrated that (1) LMP expression can be absolutely independent of EBNA2 expression, (2) the level of LMP expression is very tightly regulated, and is independent of EBV genome status (integrated or episomal) and copy number. Our findings provide compelling evidence that LMP expression has to be related to that of cellular factors that remain to be identified.

Antigens, Viral↗
PubMed1992

Expression of the APO-1 antigen in Burkitt lymphoma cell lines correlates with a shift towards a lymphoblastoid phenotype.

APO-1 is a cell surface molecule that induces apoptosis when ligated with the monoclonal antibody anti-APO-1. Expression of APO-1 and response to anti-APO-1 was investigated in a number of Epstein-Barr virus (EBV)-positive and -negative Burkitt lymphoma (BL) cell lines, in EBV-immortalized lymphoblastoid cell lines, and in cells from fresh BL biopsies. APO-1 was not expressed in EBV-negative cell lines and in EBV-positive BL cell lines with a phenotype corresponding to BL tumor biopsy cells (CD10+, CD21-, CD23-, CD30-, CD39-, CDw70-, CD77+). Accordingly, fresh BL cells obtained from three BL biopsies were APO-1 negative. EBV-positive BL cell lines that had acquired a lymphoblastoid phenotype (CD10-, CD21+, CD23+, CD30+, CD39+, CDw70+, CD77-) upon prolonged in vitro cultivation, as well as normal B-lymphoblastoid cell lines, expressed a high density of APO-1. APO-1 may, therefore, be regarded as a B-cell activation marker. APO-1 expression is not the only prerequisite for anti-APO-1-induced apoptosis because 6 of 7 APO-1-expressing EBV-positive BL cell lines were not sensitive to anti-APO-1, whereas all lymphoblastoid cell lines were killed by anti-APO-1. The sensitivity of lymphoblastoid cell lines to anti-APO-1-mediated apoptosis may open a new therapeutic approach for the treatment of EBV-induced lymphoproliferative lesions in immunocompromised individuals, because these are composed of cells with a lymphoblastoid phenotype.

Antibodies, Monoclonal↗
PubMed1992

The genetics of multiple endocrine neoplasia (MEN).

Multiple Endocrine Neoplasia (MEN) refers to the family of diseases characterized by hyperplasia and/or tumoral proliferation in various organs derived from the neural crest. MEN are transmitted in an autosomal dominant fashion in affected pedigrees with a high degree of penetrance. MEN 1 and MEN 2A/B loci have recently been mapped, respectively, to chromosomes 11 and 10 by linkage analysis using polymorphic DNA markers. These discoveries will lead (1) to a rapid understanding of the physiopathological pathway determining such syndromes and (2) to major clinical impact through the genetic screening.

Chromosome Mapping↗
PubMed1991

Epstein-Barr virus nuclear antigen 2 activates transcription of the terminal protein gene.

Transcription of the terminal protein (TP) gene of Epstein-Barr virus (EBV) in Burkitt's lymphoma cells, in EBV-negative Burkitt's lymphoma cells converted with transformation-defective (P3HR1) and transformation-competent (B95-8, AG876) EBV strains, and in EBV-immortalized cell lines was studied. A TP1 cDNA probe spanning the boundary between exons 1 and 2 and discriminating between TP1 and TP2 transcripts was used for S1 analysis. TP RNA expression varied widely in Burkitt's lymphoma cells. TP-specific transcripts were not detectable or only hardly detectable in Burkitt's lymphoma cells with the group I phenotype (CD10+ CD77+ CD21- CD23- CD30- CDw70-) as well as in P3HR1 virus-converted Burkitt's lymphoma lines. TP expression was high in Burkitt's lymphoma lines with the group II and group III phenotypes (CD21+ CD23+ CD30+ CDw70+), in B95-8 and AG876 virus-converted lines, and in EBV-immortalized cells. Detection of TP1 RNA correlated with EBNA2 expression. TP1 transcription was shown to be dependent on EBNA2 expression by stable transfection of an EBNA2 expression vector into P3HR1 virus-converted BL41 cells. EBNA2 is activating the TP1 as well as the TP2 promoter, as shown by the analysis of TP promoter-chloramphenicol acetyltransferase constructs transiently transfected into EBNA2-positive and EBNA2-negative Burkitt's lymphoma cells.

Antigens, Viral↗