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1.
J Pharm Belg ; (1): 42-54, 2014 Mar.
Artigo em Francês | MEDLINE | ID: mdl-24804393

RESUMO

INTRODUCTION: Improvement of healthcare quality and safety are two main goals for hospitals. High risk preparations of injectable drugs is one of the possible areas for improvement. In this context the production of batches of standard doses is a practical solution in response to the increased demand. Some toolkits exists to facilitate the implementation of dose banding, but, to our knowledge, no complete strategy was available until today. AIM AND PURPOSE: To propose a rational approach to analyse the possibility of implementing standard doses and choose the most relevant drugs for dose standardization. METHOD: The method is based on the analysis of literature focusing on different themes: safety, international guidelines, batch production regulation and stability studies. RESULTS: An approach on the strategies to develop is detailed for pharmacists willing to implement standard doses. All key stages are discussed: the needs of care units, the analysis and risk assessment, the stability studies and the practical implementation of the standard doses preparation and quality control. CONCLUSION: The implementation of standard doses seems a rational and necessary evolution of hospital pharmacy in response to the increase of compounding activity and the requirements of quality preparation. A global and all-inclusive approach is needed for this purpose. All parameters have to be considered to avoid errors. A process and a decision aid are suggested to facilitate the development of standard doses.


Assuntos
Preparações Farmacêuticas/administração & dosagem , Serviço de Farmácia Hospitalar/organização & administração , Química Farmacêutica , Composição de Medicamentos , Humanos , Injeções , Farmacêuticos , Qualidade da Assistência à Saúde
2.
Gynecol Obstet Fertil ; 41(12): 681-6, 2013 Dec.
Artigo em Francês | MEDLINE | ID: mdl-24200987

RESUMO

OBJECTIVES: To evaluate various surgical techniques for partial oophorectomy cryopreservation. To evaluate the consequences of prior exposure to cytotoxic therapy on the quality of the ovary removed. PATIENTS AND METHODS: Single center retrospective observational study over 4 years of women who had ovarian cryopreservation surgery for chemotherapy or radiotherapy which were at high risk of premature ovarian failure. Several techniques have been proposed: partial oophorectomy with clamping of the vascular gonadal pedicle (indirect tissue sample) without clamping (direct tissue sample) and partial oophorectomy with an automatic stapler. Ovarian tissue was immediately prepared for cryopreservation in the operating theatre. The whole sample was divided into small slices. For each ovary, a count of small slices was made. Additionally, one slice was examined to determine the presence of primordial follicles. RESULTS: Ovary was successfully removed and cryopreserved in 13 patients. Two bleeding events occurred with the direct technique, without consequences for patients. The number of fragments obtained between indirect and direct techniques was respectively 19 vs 15, P=0.18; the number of primordial follicles was 38 vs 36, P=0.87. The automatic stapler consumed too much ovarian tissue to be interesting. There were fewer fragments, 15 vs 20, P<0.05 and primordial follicles, 35 vs 40, P=0.65, after a first cycle of chemotherapy. DISCUSSION AND CONCLUSION: The vascular clamping technique is safer but with no difference in the quality of the sample tissue. One cycle of chemotherapy has a pejorative impact on the quality of the sample tissue.


Assuntos
Criopreservação/métodos , Ovário , Adolescente , Adulto , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Neoplasias Ovarianas/terapia , Ovariectomia , Estudos Retrospectivos , Adulto Jovem
3.
Gynecol Obstet Fertil ; 41(9): 562-5, 2013 Sep.
Artigo em Francês | MEDLINE | ID: mdl-23972922

RESUMO

In spite of improvements in assisted reproductive technology (ART) during the last 30 years, the rate of pregnancy remains constrained, as only about 25 % of embryo transfer lead to successful pregnancies, even with an average of two embryos replaced. Embryo selection is currently based on the establishment of morphokinetic scores, a method that obviously exhibits limitations. Therefore, the assessment of embryo development potency by criteria of higher predictive value is mandatory in order to increase the rates of pregnancy. Nowadays, there is increasing evidence that angiogenic factors might contribute to the success of the implantation and to the pregnancy outcome. Among these factors, prokineticin 1 (PROK1) and its receptors (PROKRs) constitute new targets that showed over the last ten years strong biological features directly linked to ovarian physiology, endometrial receptivity, embryo implantation and thus successful pregnancies. In ART, the rates of circulating PROK1 were reported in 2012 as significantly linked to the quality of embryonic cohort, as well as to the rates of pregnancy. Our preliminary data suggest a high potential of this cytokine in the success of implantation and pregnancy, and strongly overtones the emergency to investigate the value of its measurement in conditioned media of oocytes and embryo cultures in ART.


Assuntos
Biomarcadores/sangue , Implantação do Embrião/fisiologia , Técnicas de Reprodução Assistida , Fator de Crescimento do Endotélio Vascular Derivado de Glândula Endócrina/sangue , Células Cultivadas , Meios de Cultivo Condicionados/química , Técnicas de Cultura Embrionária , Transferência Embrionária , Feminino , Humanos , Oócitos/metabolismo , Gravidez , Resultado do Tratamento , Fator de Crescimento do Endotélio Vascular Derivado de Glândula Endócrina/análise , Fator de Crescimento do Endotélio Vascular Derivado de Glândula Endócrina/fisiologia
4.
Prog Urol ; 22(10): 561-7, 2012 Sep.
Artigo em Francês | MEDLINE | ID: mdl-22920333

RESUMO

INTRODUCTION: The purpose of this review is to relate to the operating rules of CECOS in France and the legal, medical and ethical issues raised by sperm donation. MATERIAL AND METHODS: Review of articles and consensus conferences on this subject published in Medline (PubMed) selected from 1973 and 2011 according to their relevance and Acts recorded on official legislative French websites. RESULTS: The operating rules of CECOS were established by the Act of July 29, 2004, revised 6 August 2004 and July 7, 2011. Of the 21,759 children born of ART in France in 2009, 5.1% are from a sperm donation. From 1973 to 2006, 44,045 children are born after a sperm donation. Between 1973 and 2006, 16,971 donors are presented in the CECOS and only 10,347 donors have completely made their donation process. The main indication for use of donor sperm (75% of applications) is represented by men of infertile couples with nonobstructive azoospermia, the second indication is infertile men with oligospermia. In azoospermia, the application is usually performed after failure of testicular or epididymal surgical specimen. In oligozoospermia, claims made most often after several failures of intraconjugal ART. CONCLUSION: Many questions are still present around the conception of children by sperm donation. The legitimacy of maintaining anonymity in the gift remains widely debated.


Assuntos
Técnicas de Reprodução Assistida , Espermatozoides , Doadores de Tecidos , França , Humanos , Masculino , Técnicas de Reprodução Assistida/ética , Técnicas de Reprodução Assistida/legislação & jurisprudência , Doadores de Tecidos/ética , Doadores de Tecidos/legislação & jurisprudência
5.
Gynecol Obstet Fertil ; 37(6): 546-51, 2009 Jun.
Artigo em Francês | MEDLINE | ID: mdl-19447663

RESUMO

Infertility concerns at least 70 million couples worldwide. An important proportion of cases is believed to have a genetic component, yet few causal genes have been identified so far. Hundreds of genes are probably involved in spermatogenesis and oogenesis and this genetic heterogeneity has so far hindered the identification of genes causing infertility in the human. Careful morphological examination of spermatozoa can provide cues to identify homogeneous cohorts of patients likely to have the same genetic defect. We studied a cohort of North-Africans patients with a rare phenotype of large-headed spermatozoa. Using a homozygosity mapping strategy, we could map the morbid gene and we identified the same homozygous mutation (c.144delC) in the aurora kinase C gene (AURKC) of all patients studied initially. We then genotyped a total of 62 patients. All who had a typical phenotype with close to 100% large-headed spermatozoa were homozygously mutated (n=34), whereas no AURKC mutations were detected in the others. A carrier frequency of 1/50 was established from individuals from the Maghrebian population, indicating that 1 in 10,000 men from North-African can be expected to present this form of infertility, a frequency comparable to that of Y-microdeletions, thus far the only known recurrent genetic event altering spermatogenesis. Then we demonstrated by flow cytometry that all spermatozoa have in fact a homogeneous 4C. We recommend the realisation of a molecular diagnosis to all patients with large-headed spermatozoa. ICSI is formally contraindicated for all homozygous patients who can have recourse to donor sperm or adoption. One cannot be as categorical for the patients not harbouring an AURKC mutation.


Assuntos
População Negra/genética , Infertilidade Masculina/enzimologia , Proteínas Serina-Treonina Quinases/genética , Reprodução/fisiologia , Espermatozoides/enzimologia , África do Norte , Aurora Quinase C , Aurora Quinases , Feminino , Frequência do Gene , Genótipo , Humanos , Infertilidade Masculina/etiologia , Infertilidade Masculina/genética , Masculino , Meiose/genética , Mutação/genética , Proteínas Serina-Treonina Quinases/fisiologia , Cabeça do Espermatozoide , Espermatozoides/patologia
6.
Gynecol Obstet Fertil ; 37(6): 519-22, 2009 Jun.
Artigo em Francês | MEDLINE | ID: mdl-19447664

RESUMO

During their post-meiotic maturation, male germ cells undergo an extensive reorganization of their genome, during which histones become globally hyperacetylated, are then removed and progressively replaced by transition proteins and finally by protamines. The latter are known to tightly associate with DNA in the mature sperm cell. Although this is a highly conserved and fundamental biological process, which is a necessary prerequisite for the transmission of the male genome to the next generation, its molecular basis remains mostly unknown. We have identified several key factors involved in this process, and their detailed functional study has enabled us to propose the first model describing molecular mechanisms involved in post-meiotic male genome reprogramming. One of them, Bromodomain Testis Specific (BRDT), has been the focus of particular attention since it possesses the unique ability to specifically induce a dramatic compaction of acetylated chromatin. Interestingly, a mutation was found homozygous in infertile men which, according to our structural and functional studies, disrupts the function of the protein. A combination of molecular structural and genetic approaches has led to a comprehensive understanding of new major actors involved in the male genome reprogramming and transmission.


Assuntos
Epigênese Genética , Infertilidade Masculina/genética , Meiose/fisiologia , Espermatogênese/fisiologia , Acetilação , Cromatina/química , Cromatina/metabolismo , Epigênese Genética/fisiologia , Histonas/metabolismo , Humanos , Masculino , Meiose/genética , Proteínas Nucleares/química , Proteínas Nucleares/genética , Espermatogênese/genética , Espermatozoides/metabolismo
7.
Hum Reprod ; 22(7): 1854-60, 2007 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-17582144

RESUMO

BACKGROUND: Cytogenetically detectable aberrations of the Y chromosome, such as isodicentrics, rings or translocations are sometimes associated with male non-obstructive infertility. This report presents a detailed analysis of the clinical, cytogenetic and molecular data in three patients with a re-arranged Y chromosome. METHODS: Patients A and B were azoospermic, whereas patient C was cryptozoospermic. All had a somatic mosaic karyotype including a population of 45,X cells and a cell line with a re-arranged Y chromosome. A molecular and FISH analysis of their re-arranged Y was undertaken, which specifically focussed on the presence of the AZFa, b and c regions. RESULTS: The AZFa region was present in all the three patients. The AZFb and AZFc regions were absent in patients A and B, whereas, in patient C, the distal part of AZFb and the whole AZFc region were deleted. Moreover, in this patient, the AZF FISH analysis revealed a mosaicism for the size of the AZF deletion within the re-arranged Y, suggesting a progressive enlargement of the deletion during cell mitotic divisions. CONCLUSIONS: This investigation allowed not only a more precise description of the abnormal Y, but also shed light on how this re-arrangement could be involved in the infertility phenotype.


Assuntos
Azoospermia/genética , Mapeamento Cromossômico/métodos , Cromossomos Humanos Y , Oligospermia/genética , Aberrações Cromossômicas , Deleção Cromossômica , Citogenética , Feminino , Humanos , Hibridização in Situ Fluorescente , Infertilidade/genética , Cariotipagem , Masculino , Recombinação Genética , Aberrações dos Cromossomos Sexuais
8.
Int J Androl ; 30(3): 153-62, 2007 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-17239087

RESUMO

Patients with severe spermatogenesis impairment can now successfully father a child thanks to the use of intracytoplasmic sperm injection (ICSI). In oligozoospermic patients, many studies have reported significantly higher sperm aneuploidy rates and therefore an increased risk of transmitting a chromosomal abnormality via the injection of abnormal spermatozoa. However, the frequency of aneuploidy is highly variable between patients. The aim of the present work was to identify clinical and biological factors, which, together with non-obstructive oligozoospermia, could be predictive of elevated sperm aneuploidies. The sperm aneuploidy rates for chromosomes X, Y, 13, 18 and 21 were assessed in 31 infertile men with well-characterized spermatogenesis impairment, and in a population of control men with proven fertility. The frequency of sperm aneuploidy was compared between several patient subgroups according to their clinical and biological factors. Nearly half of the oligozoospermic males (15/31) had a significantly increased disomy rate for at least one of the five chromosomes compared with that observed in the control population (mean disomy rates + 1.96 standard deviation). Factors significantly associated with higher numbers of aneuploid sperm were cigarette smoking, an elevated follicle-stimulating hormone level, a sperm concentration less than 1 m/mL, and a severe teratozoospermia. Hence, several factors predictive of an increased risk of sperm aneuploidy rates were identified in ICSI male candidates with a non-obstructive oligozoospermia.


Assuntos
Aneuploidia , Astenozoospermia/fisiopatologia , Oligospermia/fisiopatologia , Espermatozoides/anormalidades , Adulto , Astenozoospermia/genética , Anormalidades Congênitas/genética , Hormônio Foliculoestimulante/sangue , Humanos , Masculino , Pessoa de Meia-Idade , Oligospermia/genética , Valor Preditivo dos Testes , Fumar , Contagem de Espermatozoides , Espermatogênese
9.
Gynecol Obstet Fertil ; 34(9): 831-5, 2006 Sep.
Artigo em Francês | MEDLINE | ID: mdl-16949851

RESUMO

In addition to genetic information, the spermatozoon carries another type of information, named epigenetic, which is not associated with variations of the DNA sequence. In somatic cells, it is now generally admitted that epigenetic information is not only regulated by DNA methylation but also involves modifications of the genome structure, or epigenome. During male germ cell maturation, the epigenome is globally re-organized, since most histones, which are associated to DNA in somatic cells, are removed and replaced by sperm specific nuclear proteins, the protamines, responsible for the tight compaction of the sperm DNA. However, a small proportion of histones, and probably other proteins, are retained within the sperm nucleus, and the structure of the sperm genome is actually heterogeneous. This heterogeneity of the sperm epigenome could support an epigenetic information, transmitted to the embryo, which could be crucial for its development. Although it is nowadays possible to appreciate the global structure of the sperm genome, the precise constitution of the sperm epigenome remains unknown. In particular, very recent data suggest that specific regions of the genome could be associated with particular proteins and define specific structures. This structural partitioning of the sperm genome could convey important epigenetic information, crucial for the embryo development.


Assuntos
Epigênese Genética , Espermatozoides , DNA/genética , Humanos , Infertilidade Masculina/genética , Masculino , Meiose , Mutação , Reprodução , Espermatogênese/genética , Espermatozoides/química
11.
Gynecol Obstet Fertil ; 32(9): 785-91, 2004 Sep.
Artigo em Francês | MEDLINE | ID: mdl-15380763

RESUMO

Thanks to the success of new assisted reproductive technology, including sperm microinjection (i.c.s.i.), men with severe spermatogenesis impairments can now become biological fathers. Whether the germinal cell used for i.c.s.i. is conveying appropriate genetic and epigenetic information is an important concern. However, to date, there is a huge lack of data on which information is epigenetically conveyed to the offspring and how. The basic support for epigenetic marks is the nucleus structure. During spermatogenesis, a major re-organization of the male germ cells nucleus structure occurs, which includes a global condensation associated with a removal of most core somatic histones and their replacement by sperm-specific nuclear proteins. The available data on the molecular mechanisms involved in this process and how it could relate to the setting of male-specific epigenetic information is reviewed and discussed in light of our current knowledge about nuclear structure and functions.


Assuntos
Núcleo Celular/ultraestrutura , Espermatozoides/ultraestrutura , Cromatina/ultraestrutura , Metilação de DNA , Humanos , Masculino , Meiose , Injeções de Esperma Intracitoplásmicas , Espermatogênese
12.
Hum Reprod ; 17(5): 1292-8, 2002 May.
Artigo em Inglês | MEDLINE | ID: mdl-11980754

RESUMO

BACKGROUND: Macrocephalic or large headed sperm with multiflagella is a rare abnormality often associated with infertility. Sperm chromosomal abnormalities could be associated with this specific morphological abnormality. METHODS: The cytogenetic content of large-headed sperm was assessed by dual and three-colour fluorescence in-situ hybridization in three patients carrying this specific morphological abnormality. RESULTS: In all patients nearly all sperm contained at least one copy of each sex chromosome, and in more than half of them at least two copies of either chromosome 1 or 18 were identified. In some sperm a tetraploidy was found. CONCLUSIONS: These observations suggested that both meiotic I and II divisions were affected by incomplete partition of homologous chromosomes during meiosis I and of sister chromatids during meiosis II associated with a failure of nuclear cleavage. Furthermore, they provide evidence for a clear relationship between a specific morphological abnormality of the sperm and their abnormal cytogenetic content. The treatment of infertility using ICSI would probably be unsuccessful and have a high genetic risk in these cases.


Assuntos
Ploidias , Cabeça do Espermatozoide/ultraestrutura , Espermatozoides/fisiologia , Adulto , Núcleo Celular/fisiologia , Núcleo Celular/ultraestrutura , Aberrações Cromossômicas , Cromossomos Humanos Par 1/ultraestrutura , Cromossomos Humanos Par 18/ultraestrutura , Anormalidades Congênitas/genética , Análise Citogenética , Dosagem de Genes , Humanos , Hibridização in Situ Fluorescente , Masculino , Pessoa de Meia-Idade , Cromossomos Sexuais/ultraestrutura , Espermatozoides/anormalidades
13.
Lancet ; 357(9274): 2104-5, 2001 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-11445108

RESUMO

Intracytoplasmic sperm injection (ICSI) has given some patients with Klinefelter's syndrome (ie, men with an XXY sex-chromosome profile) the chance to become fathers, but the genetic makeup of the spermatozoa used for the injection is a concern. We studied the segregation of the sex chromosomes and chromosomes 1 and 21 by multicolour fluorescence in-situ hybridisation in a patient with non-mosaic Klinefelter's syndrome who was a candidate for ICSI. As other workers have found, we saw a higher rate of 24,XX and 24,XY spermatozoa in the patient than in controls. However, we also found a much higher frequency of disomy 21 in the spermatozoa of this patient than in controls (6.2 vs 0.4%). Any child conceived by ICSI using this man's sperm will thus have a proportionally higher risk of trisomy 21.


Assuntos
Aberrações Cromossômicas , Síndrome de Down , Síndrome de Klinefelter/genética , Injeções de Esperma Intracitoplásmicas , Espermatozoides/citologia , Síndrome de Down/diagnóstico , Síndrome de Down/etiologia , Testes Genéticos , Humanos , Hibridização in Situ Fluorescente , Masculino
15.
J Chromatogr B Biomed Sci Appl ; 729(1-2): 65-74, 1999 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-10410928

RESUMO

The in vitro N-acetylgalactosaminylation by human gastric UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferases was assessed using the peptide motif GTTPSPVPTTSTTSAP, which is found naturally in the tandem repeat domains of the apomucin encoded by the gene MUC5AC. This peptide appeared to be an excellent tool for obtaining an insight into the extensive O-glycosylation processes of apomucins. Up to six N-acetylgalactosamines were added and the given glycopeptide species were well separated by capillary zone electrophoresis. Moreover, the degree of glycosylation (number of monosaccharide O-linked attachments) could be determined by MALDI-mass spectrometry without prior separation. Using different incubation times, we evidenced the accumulation of various glycopeptides, suggesting that the total glycosylation of an apomucin-peptide requires orderly N-acetylgalactosaminylation processing. This information was completed by experimental data showing that N-acetylgalactosaminylated octapeptides (the peptide backbones of which are part of GTTPSPVPTTSTTSAP) were able to selectively inhibit some N-acetylgalactosaminyltransferases. Our results suggest that this inhibition may influence the quality of the intermediate products appearing during the in vitro O-glycosylation process.


Assuntos
Eletroforese Capilar/métodos , Mucinas/metabolismo , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Sequência de Aminoácidos , Glicosilação , Humanos , Dados de Sequência Molecular , Mucina-5AC , Mucinas/química , Serina/química , Treonina/química
17.
J Chromatogr A ; 805(1-2): 285-93, 1998 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-9618923

RESUMO

A method for the analysis of O-glycosylation of peptides has been developed, combining capillary electrophoretic (CE) separation and electrospray ionization mass spectrometry. Synthetic peptides with apomucin 'tandem repeat' sequences which present potential O-glycosylation sites on threonine and serine residues were used as model system. In vitro O-glycosylated peptide samples were obtained by incubation of the peptides with human gastric microsomal homogenates containing N-acetylgalactosamine transferase activity in the presence of uridyl diphosphate N-acetylgalactosamine (UDP-GalNAc). CE was carried out in the presence of the linear polymer poly(vinyl alcohol) in the electrophoresis solvent, resulting in a greatly improved separation of the up to five different glycoforms of peptides with lengths of 8, 16 or 23 amino acids, and the unglycosylated peptides. After separation and peak collection, the number of modifications with N-acetyl galactosamine (GalNAc) could be determined by electrospray ionization mass spectrometry. The glycosylation pattern was shown to depend on the amino acid sequence of the peptides.


Assuntos
Oligopeptídeos/isolamento & purificação , Álcool de Polivinil/química , Sequência de Aminoácidos , Eletroforese Capilar , Glicosilação , Indicadores e Reagentes , Espectrometria de Massas , Dados de Sequência Molecular
18.
J Pept Res ; 51(5): 346-54, 1998 May.
Artigo em Inglês | MEDLINE | ID: mdl-9606014

RESUMO

The in vitro O-glycosylation reaction of the MUC5AC mucin motif peptide, TTSAPTTS (in one-letter code), was achieved with human gastric microsomal homogenates. The analyses using capillary electrophoresis online coupled with electrospray mass spectrometry and further Edman degradation of the purified products (obtained by capillary electrophoresis at preparative scale) allowed us to distinguish two components at close masses: the addition of a mass of 202 corresponded to an N-terminal elongation of the peptide TTSAPTTS with the dipeptide (TT) and the addition of a mass of 203 corresponded to an N-acetylgalactosamine O-linkage. Using different peptidase inhibitors, a dipeptidyl peptidase/transferase activity was further characterized. A thiol dependence and an inhibition by H-Gly-PheCHN2 (specific to cathepsin C activity) were found. Moreover, besides TTSAPTTS, other MUC5AC motif peptides (GTTPSPVP, TSAPTTS) were also dipeptide donors (GT and TS, respectively) and our results suggested the involvement of a single dipeptidyl peptidase/transferase activity. Finally, this latter activity modified the in vitro GalNAc incorporation rates when using our selected MUC5AC motif peptides. Our study therefore shows that caution must be taken to prevent peptidic substrate elongation while performing in vitro O-glycosylation with microsomal preparations as the enzyme source. In fact, the results of the N-acetylgalactosamine incorporation rates and thus the microsomal N-acetylgalactosamine transferase affinity can be misinterpreted if dipeptidyl peptidase/transferase activity is not inhibited by the thiol inhibitor E-64 or the cathepsin C inhibitor H-Gly-PheCHN2.


Assuntos
Dipeptidil Peptidases e Tripeptidil Peptidases/química , Microssomos/metabolismo , Mucinas/química , Fragmentos de Peptídeos/química , Catepsina C , Dipeptidil Peptidases e Tripeptidil Peptidases/metabolismo , Mucosa Gástrica/metabolismo , Glicosilação , Humanos , Mucina-5AC , Mucinas/metabolismo , Fragmentos de Peptídeos/síntese química , Fragmentos de Peptídeos/metabolismo , Estômago/ultraestrutura , Especificidade por Substrato
19.
Glycoconj J ; 15(3): 275-82, 1998 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-9579804

RESUMO

The present work was carried out to study the role of the peptide moiety in the addition of O-linked N-acetylgalactosamineto human apomucin using human crude microsomal homogenates from gastric mucosa (as enzyme source) and a series of peptide acceptors representative of tandem repeat domains deduced from the MUC5AC mucin gene (expressed in the gastric mucosa). Being rich in threonine and serine placed in clusters, these peptides provided several potential sites for O-glycosylation. The glycosylated products were analysed by a combination of electrospray mass spectrometry and capillary electrophoresis in order to isolate the glycopeptides and to determine their sequence by Edman degradation. The O-glycosylation of our MUC5AC motif peptides gave information on the specificity and activity of the gastric microsomal UDP-N-acetylgalactosamine:polypeptide N-acetylgalactosaminyltransferase(s). The proline residues and the induced-conformations are of great importance for the recognition of MUC5AC peptides but they are not the only factors for the choice of the O-glycosylation sites. Moreover, for the di-glycosylated peptides, the flanking regions of the proline residues strongly influence the site of the second O-glycosylation.


Assuntos
Mucinas/química , Mucinas/metabolismo , N-Acetilgalactosaminiltransferases/metabolismo , Sequência de Aminoácidos , Sítios de Ligação , Mucosa Gástrica/enzimologia , Glicosilação , Humanos , Técnicas In Vitro , Microssomos/enzimologia , Dados de Sequência Molecular , Mucina-5AC , Oligopeptídeos/química , Oligopeptídeos/metabolismo , Conformação Proteica , Especificidade por Substrato , Polipeptídeo N-Acetilgalactosaminiltransferase
20.
Biochimie ; 80(1): 69-73, 1998 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-9587664

RESUMO

The selected-acceptor substrate peptide (TTSAPTTS), deduced from the human mucin gene MUC5AC (expressed essentially in the human gastric and tracheobronchial mucosa), was used to assay polypeptide:N-acetylgalactosaminyltransferases (GalNAc transferases) of different microsomal preparations, obtained from gastric and colonic mucosa in normal and tumoral situations. The O-glycosylated products, analyzed by capillary electrophoresis and electrospray mass spectrometry, showed a variable number of GalNAc O-linked to the different hydroxy amino acids of TTSAPTTS, depending on the tissue studied. Our observations were consistent with the existence of more than one form of GalNAc transferases which were expressed differentially in the gastrointestinal tract (stomach and/or colon). The levels of enzyme activities showed a tissue-specific pattern as they were high in normal colonic tissue and low in colon cancer. On the other hand, in the tumoral gastric tissue (displaying intestinal metaplasia) a high level of GalNAc transferase activities was obtained, similar to that found in the normal colon. Moreover, slight discrepancies (activities and number of O-linked GalNAc) were only detected between normal gastric and tumoral colonic preparations. Thus, the data indicated that the dedifferentiation of the gastric cancer tissue may induce GalNAc transferase activities similar to those in the normal colonic, tissue and that colonic and gastric tissues may contain families of glycosyltransferases involved specifically in reaction towards particular peptide or protein substrates. In addition, the analysis by capillary electrophoresis and electrospray mass spectrometry revealed, in tumoral gastric as well as in normal colonic tissues, a high dipeptidylaminotransferase activity inducing an elongation of TTSAPTTS by dithreonine. This activity was low in normal gastric and tumoral colonic tissues.


Assuntos
Neoplasias do Colo/metabolismo , Mucosa Gástrica/metabolismo , Microssomos/enzimologia , Mucinas/metabolismo , N-Acetilgalactosaminiltransferases/metabolismo , Animais , Glicosilação , Humanos , Mucina-5AC , Suínos , Polipeptídeo N-Acetilgalactosaminiltransferase
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