Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 285
Filtrar
1.
Tech Coloproctol ; 23(9): 831-842, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31388861

RESUMO

BACKGROUND: An organ-preserving strategy may be a valid alternative in the treatment of selected patients with rectal cancer after neoadjuvant radiotherapy. Preoperative assessment of the risk for tumor recurrence is a key component of surgical planning. The aim of the present study was to increase the current knowledge on the risk factors for tumor recurrence. METHODS: The present study included individual participant data of published studies on rectal cancer surgery. The literature was reviewed according to according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses of Individual Participant Data checklist (PRISMA-IPD) guidelines. Series of patients, whose data were collected prospectively, having neoadjuvant radiotherapy followed by transanal local excision for rectal cancer were reviewed. Three independent series of univariate/multivariate binary logistic regression models were estimated for the risk of local, systemic and overall recurrence, respectively. RESULTS: We identified 15 studies, and 7 centers provided individual data on 517 patients. The multivariate analysis showed higher local and overall recurrences for ypT3 stage (OR 4.79; 95% CI 2.25-10.16 and OR 6.43 95% CI 3.33-12.42), tumor size after radiotherapy > 10 mm (OR 5.86 95% CI 2.33-14.74 and OR 3.14 95% CI 1.68-5.87), and lack of combined chemotherapy (OR 3.68 95% CI 1.78-7.62 and OR 2.09 95% CI 1.10-3.97), while ypT3 was the only factor correlated with systemic recurrence (OR 5.93). The analysis of survival curves shows that the overall survival is associated with ypT and not with cT. CONCLUSIONS: Local excision should be offered with caution after neoadjuvant chemoradiotherapy to selected patients with rectal cancers, who achieved a good response to neoadjuvant chemoradiotherapy.


Assuntos
Terapia Neoadjuvante/estatística & dados numéricos , Recidiva Local de Neoplasia/etiologia , Protectomia/estatística & dados numéricos , Radioterapia Adjuvante/estatística & dados numéricos , Neoplasias Retais/terapia , Idoso , Intervalo Livre de Doença , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Recidiva Local de Neoplasia/mortalidade , Recidiva Local de Neoplasia/patologia , Estadiamento de Neoplasias , Período Pós-Operatório , Protectomia/métodos , Neoplasias Retais/mortalidade , Neoplasias Retais/patologia , Fatores de Risco , Cirurgia Endoscópica Transanal/métodos , Cirurgia Endoscópica Transanal/estatística & dados numéricos , Resultado do Tratamento
2.
Eur J Paediatr Dent ; 19(1): 67-69, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29569457

RESUMO

AIM: The aim of this article is to describe the use of a titanium TSME appliance for patients with allergy to resin and nickel. We aim to highlight the optimal way to avoid problems such as stomatitis and peri-labial dermatitis, which generally appear in patients who use traditional orthodontic appliances made in acrylic resin and steel. MATERIALS AND METHODS: The construction of a titanium appliance is described and a case treated with it is reported. RESULTS: The titanium TSME presented in this paper has excellent biocompatibility due to its ability to form superficial oxides, which prevent oxidation and thus corrosion. CONCLUSION: The non-allergic properties of titanium allow to propose it as an alternative in patients with a long-term history of allergic reactions to nichel.


Assuntos
Hipersensibilidade/prevenção & controle , Níquel/imunologia , Desenho de Aparelho Ortodôntico , Técnica de Expansão Palatina/instrumentação , Titânio/imunologia , Materiais Biocompatíveis , Criança , Humanos , Hipersensibilidade/etiologia , Masculino , Teste de Materiais
3.
Am J Transplant ; 17(2): 420-431, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27402017

RESUMO

The reasons for the increased incidence of de novo anti-human leukocyte antibody (HLA) donor-specific antibodies (DSAs) observed after kidney allograft nephrectomy are not fully understood. One advocated mechanism suggests that at graft loss, DSAs are not detected in the serum because they are fixed on the nonfunctional transplant; removal of the kidney allows DSAs to then appear in the blood circulation. The aim of our study was to compare anti-HLA antibodies present in the serum and in the graft at the time of an allograft nephrectomy. Using solid-phase assays, anti-HLA antibodies were searched for in the sera of 17 kidney transplant patients undergoing allograft nephrectomy. No anti-HLA antibodies were detected in the graft if they were not also detected in the serum. Eleven of the 12 patients who had DSAs detected in their sera also had DSAs detected in the grafts. Epitopic analysis revealed that most anti-HLA antibodies detected in removed grafts were directed against the donor. In summary, our data show that all anti-HLA antibodies that were detected in grafts were also detected in the sera. These intragraft anti-HLA antibodies are mostly directed against the donor at an epitopic level but not always at an antigenic level.


Assuntos
Epitopos/imunologia , Rejeição de Enxerto/etiologia , Antígenos HLA/imunologia , Isoanticorpos/sangue , Transplante de Rim/efeitos adversos , Nefrectomia/efeitos adversos , Doadores de Tecidos , Adulto , Alelos , Aloenxertos , Feminino , Sobrevivência de Enxerto , Humanos , Masculino
4.
Am J Transplant ; 16(5): 1474-9, 2016 05.
Artigo em Inglês | MEDLINE | ID: mdl-26587971

RESUMO

There is no approved therapy for hepatitis C virus (HCV) infection after kidney transplantation, and no data regarding the use of new-generation direct antiviral agents (DAAs) have been published so far. The aims of this pilot study were to assess the efficacy and safety of an interferon-free sofosbuvir-based regimen to treat chronic HCV infection in kidney transplant recipients. Twenty-five kidney transplant recipients with chronic HCV infection were given, for 12 (n = 19) or 24 weeks (n = 6), sofosbuvir plus ribavirin (n = 3); sofosbuvir plus daclatasvir (n = 4); sofosbuvir plus simeprevir, with (n = 1) or without ribavirin (n = 6); sofosbuvir plus ledipasvir, with (n = 1) or without ribavirin (n = 9); and sofosbuvir plus pegylated-interferon plus ribavirin (n = 1). A rapid virological response, defined by undetectable viremia at week 4 after starting DAA therapy, was observed in 22 of the 25 patients (88%). At the end of therapy, HCV RNA was undetectable in all patients. At 4 and 12 weeks after completing DAA therapy, all had a sustained virological response. The tolerance to anti-HCV therapy was excellent and no adverse event was observed. A significant decrease in calcineurin inhibitor levels was observed after HCV clearance. New-generation oral DAAs are efficient and safe to treat HCV infection after kidney transplantation.


Assuntos
Antivirais/uso terapêutico , Sobrevivência de Enxerto/efeitos dos fármacos , Hepacivirus/efeitos dos fármacos , Hepatite C/tratamento farmacológico , Falência Renal Crônica/complicações , Transplante de Rim/efeitos adversos , Sofosbuvir/uso terapêutico , DNA Viral/genética , Feminino , Seguimentos , Taxa de Filtração Glomerular , Hepacivirus/genética , Hepatite C/virologia , Humanos , Falência Renal Crônica/cirurgia , Testes de Função Renal , Masculino , Pessoa de Meia-Idade , Projetos Piloto , Prognóstico , Fatores de Risco , Segurança , Carga Viral
5.
Am J Transplant ; 16(9): 2661-9, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-26998676

RESUMO

Little is known about the impact of posttransplant blood transfusion on the sensitization of anti-HLA antibodies and the formation of donor-specific antibodies (DSAs). The aims of our study were to determine the 1-year incidence of DSAs (assessed using a solid-phase assay) and antibody-mediated rejection (AMR) in kidney transplant patients who had or had not received a blood transfusion during the first year after transplantation. Included were 390 non-HLA-sensitized patients who had received an ABO-compatible kidney transplant and had not previously or simultaneously received a nonkidney transplant. Overall, 64% of patients received a red blood cell transfusion within the first year after transplantation, most within the first month. The overall 1-year incidence of DSAs was significantly higher in patients that had undergone transfusion (7.2% vs. 0.7% in patients with no transfusion, p < 0.0001). AMR occurred more often in the transfusion group (n = 15, 6%) compared with the nontransfusion group (n = 2, 1.4%; p = 0.04). Blood transfusion was an independent predictive factor for de novo DSA formation but not for AMR. Patients who had a transfusion and developed DSAs were more often treated with cyclosporin A (n = 10, 55.5%) rather than tacrolimus (n = 45, 19.4%; p = 0.0001). In conclusion, early posttransplant blood transfusion may increase immunological risk, especially in underimmunosuppressed patients.


Assuntos
Transfusão de Eritrócitos/efeitos adversos , Rejeição de Enxerto/epidemiologia , Isoanticorpos/sangue , Falência Renal Crônica/cirurgia , Transplante de Rim/efeitos adversos , Doadores de Tecidos , Estudos de Casos e Controles , Feminino , Seguimentos , Taxa de Filtração Glomerular , Rejeição de Enxerto/etiologia , Sobrevivência de Enxerto , Antígenos HLA/imunologia , Humanos , Incidência , Isoanticorpos/imunologia , Testes de Função Renal , Masculino , Pessoa de Meia-Idade , Prognóstico , Fatores de Risco
7.
Am J Transplant ; 15(1): 190-9, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25496195

RESUMO

Pneumocystis pneumonia (PCP) in solid organ transplant (SOT) recipients becomes rare in the immediate posttransplantation period thanks to generalized prophylaxis. We aimed to identify the predictive factors for PCP in the era of universal prophylaxis and to propose a strategy for preventing PCP beyond the first year after transplantation. In a retrospective case-control study, 33 SOT cases with PCP diagnosed between 2004 and 2010 were matched with two controls each to identify risk factors for PCP by uni- and multivariate analysis. All the patients benefited from 6 months of posttransplantation trimethoprim-sulfamethoxazole prophylaxis. Most PCP in SOT patients occurred during the second year posttransplantation (33%). By univariate analysis, age, nonuse of tacrolimus, total and CD4 lymphocyte counts, gamma-globulin concentration and cytomegalovirus (CMV) infection appeared to be PCP risk factors. In the final multivariate analysis, age (adjusted odds ratio [OR] 3.7, 95% confidence interval [CI]: 1.3-10.4), CMV infection (OR: 5.2, 95% CI: 1.8-14.7) and total lymphocyte count (OR: 3.9, 95% CI: 1.4-10.7) were found to be independently associated with PCP. The second year posttransplantation appeared to be the new period of highest risk of PCP. Age, CMV viremia and lymphocytes were the most pertinent predictive criteria to evaluate the risk of PCP in clinical practice.


Assuntos
Antibioticoprofilaxia , Antifúngicos/uso terapêutico , Rejeição de Enxerto/etiologia , Transplante de Órgãos , Pneumonia por Pneumocystis/etiologia , Transplantados , Combinação Trimetoprima e Sulfametoxazol/uso terapêutico , Estudos de Casos e Controles , Citomegalovirus/patogenicidade , Infecções por Citomegalovirus/complicações , Infecções por Citomegalovirus/microbiologia , Feminino , Seguimentos , Rejeição de Enxerto/diagnóstico , Rejeição de Enxerto/tratamento farmacológico , Sobrevivência de Enxerto , Humanos , Hospedeiro Imunocomprometido , Masculino , Pessoa de Meia-Idade , Pneumocystis carinii , Pneumonia por Pneumocystis/diagnóstico , Pneumonia por Pneumocystis/tratamento farmacológico , Complicações Pós-Operatórias , Estudos Retrospectivos , Fatores de Risco , Doadores de Tecidos
11.
Am J Transplant ; 14(4): 867-75, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24580771

RESUMO

Although large retrospective studies have identified the presence of donor-specific antibodies (DSAs) to be a risk factor for rejection and impaired survival after liver transplantation, the long-term predicted pathogenic potential of individual DSAs after liver transplantation remains unclear. We investigated the incidence, prevalence and consequences of DSAs in maintenance liver transplant (LT) recipients. Two hundred sixty-seven LT recipients, who had undergone transplantation at least 6 months previously and had been screened for DSAs at least twice using single-antigen bead technology, were included and tested annually for the presence of DSAs. At a median of 51 months (min-max: 6-220) after an LT, 13% of patients had DSAs. At a median of 36.5 months (min-max: 2-45) after the first screening, 9% of patients have developed de novo DSAs. The sole predictive factor for the emergence of de novo DSAs was retransplantation (OR 3.75; 95% CI 1.28-11.05, p = 0.025). Five out of 21 patients with de novo DSAs (23.8%) developed an antibody-mediated rejection. Fibrosis score was higher among patients with DSAs. In conclusion, monitoring for the development of DSAs in maintenance LT patients is useful in case of graft dysfunction and to identify patients with a high risk of developing liver fibrosis.


Assuntos
Rejeição de Enxerto/etiologia , Antígenos HLA/sangue , Isoanticorpos/sangue , Cirrose Hepática/etiologia , Hepatopatias/cirurgia , Transplante de Fígado/efeitos adversos , Adolescente , Adulto , Idoso , Feminino , Seguimentos , Rejeição de Enxerto/epidemiologia , Rejeição de Enxerto/mortalidade , Sobrevivência de Enxerto , Antígenos HLA/imunologia , Humanos , Incidência , Isoanticorpos/imunologia , Cirrose Hepática/epidemiologia , Cirrose Hepática/mortalidade , Hepatopatias/complicações , Hepatopatias/mortalidade , Masculino , Pessoa de Meia-Idade , Prevalência , Prognóstico , Estudos Prospectivos , Reoperação , Estudos Retrospectivos , Fatores de Risco , Taxa de Sobrevida , Adulto Jovem
12.
Opt Express ; 22(5): 5375-86, 2014 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-24663877

RESUMO

We present a study of Yb:YAG active media slabs, based on a ceramic layered structure with different doping levels. We developed a procedure allowing 3D numerical analysis of the slab optical properties as a consequence of the thermal load induced by the pump process. The simulations are compared with a set of experimental results in order to validate the procedure. These structured ceramics appear promising in appropriate geometrical configurations, and thus are intended to be applied in the construction of High Energy Diode Pumped Solid State Laser (DPSSL) systems working in high repetition-rate pulsed regimes.

13.
Nature ; 456(7221): 477-9, 2008 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-19037310

RESUMO

A plume of water vapour escapes from fissures crossing the south polar region of the Saturnian moon Enceladus. Tidal deformation of a thin surface crust above an internal ocean could result in tensile and compressive stresses that would affect the width of the fissures; therefore, the quantity of water vapour released at different locations in Enceladus' eccentric orbit is a crucial measurement of tidal control of venting. Here we report observations of an occultation of a star by the plume on 24 October 2007 that revealed four high-density gas jets superimposed on the background plume. The gas jet positions coincide with those of dust jets reported elsewhere inside the plume. The maximum water column density in the plume is about twice the density reported earlier. The density ratio does not agree with predictions-we should have seen less water than was observed in 2005. The ratio of the jets' bulk vertical velocities to their thermal velocities is 1.5 +/- 0.2, which supports the hypothesis that the source of the plume is liquid water, with gas accelerated to supersonic velocity in nozzle-like channels.

14.
Minerva Stomatol ; 63(6): 229-37, 2014 Jun.
Artigo em Inglês, Italiano | MEDLINE | ID: mdl-25267152

RESUMO

AIM: Aim of the present study was to present a case report of a patient suffering from pycnodysostosis and assess how it may manifest and affect the dental/ orthodontic treatment. METHODS: An 11-year-old patient who was diagnosed with pycnodysostosis at the age of 18 months, attended the orthodontics department requiring treatment for extensive carious lesions, periodontal disease and severe crowding. RESULTS: After an accurate radiographic, clinical and orthodontic assessment of the patient taking into consideration the severity of the condition and the patient's necessities, we have formulated a treatment plan, which was accepted by both the patient and parents. We took into consideration the risks and benefits of the options available and the requests of the patient. CONCLUSION: We have decided to opt for the extraction of teeth to relieve the crowding as this was impeding good oral hygiene and hence increasing the risk of caries and periodontal disease. Such patients must be placed under an oral hygiene prevention scheme, a treatment plan must be accurately designed and the patient must be constantly motivated.


Assuntos
Picnodisostose/terapia , Aparelhos Ativadores , Reabsorção Óssea , Cefalometria , Criança , Terapia Combinada , Cárie Dentária/etiologia , Suscetibilidade a Doenças , Fraturas Ósseas/etiologia , Fraturas Espontâneas/etiologia , Humanos , Masculino , Má Oclusão/etiologia , Má Oclusão/cirurgia , Ortodontia Corretiva , Periodontite/etiologia , Picnodisostose/complicações , Picnodisostose/diagnóstico por imagem , Picnodisostose/genética , Radiografia , Crânio/anormalidades , Extração Dentária
15.
CNS Neurosci Ther ; 30(3): e14448, 2024 03.
Artigo em Inglês | MEDLINE | ID: mdl-37718696

RESUMO

BACKGROUND: miRNA-based strategies have recently emerged as a promising therapeutic approach in several neurodegenerative diseases. Unregulated cation influx is implicated in several cellular mechanisms underlying neural cell death during ischemia. The brain constitutively active isoform of transient receptor potential melastatin 7 (TRPM7) represents a glutamate excitotoxicity-independent pathway that significantly contributes to the pathological Ca2+ overload during ischemia. AIMS: In the light of these premises, inhibition of TRPM7 may be a reasonable strategy to reduce ischemic injury. Since TRPM7 is a putative target of miRNA135a, the aim of the present paper was to evaluate the role played by miRNA135a in cerebral ischemia. Therefore, the specific objectives of the present paper were: (1) to evaluate miR135a expression in temporoparietal cortex of ischemic rats; (2) to investigate the effect of the intracerebroventricular (icv) infusion of miR135a on ischemic damage and neurological functions; and (3) to verify whether miR135a effects may be mediated by an alteration of TRPM7 expression. METHODS: miR135a expression was evaluated by RT- PCR and FISH assay in temporoparietal cortex of ischemic rats. Ischemic volume and neurological functions were determined in rats subjected to transient middle cerebral artery occlusion (tMCAo) after miR135a intracerebroventricular perfusion. Target analysis was performed by Western blot. RESULTS: Our results demonstrated that, in brain cortex, 72 h after ischemia, miR135a expression increased, while TRPM7 expression was parallelly downregulated. Interestingly, miR135a icv perfusion strongly ameliorated the ischemic damage and improved neurological functions, and downregulated TRPM7 protein levels. CONCLUSIONS: The early prevention of TRPM7 activation is protective during brain ischemia.


Assuntos
Lesões Encefálicas , Isquemia Encefálica , Canais de Cátion TRPM , Ratos , Animais , Canais de Cátion TRPM/genética , Canais de Cátion TRPM/metabolismo , Isquemia Encefálica/tratamento farmacológico , Isquemia Encefálica/metabolismo , Encéfalo/metabolismo , Infarto da Artéria Cerebral Média
16.
Am J Transplant ; 13(8): 2179-85, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23763583

RESUMO

Thrombotic microangiopathy (TMA) is one of the hallmark vascular lesions of antiphospholipid syndrome nephropathy (APSN). These lesions are at high risk of recurrence after kidney transplantation. The complement pathway is thought to be active in this process. We used eculizumab to treat three consecutive kidney transplant recipients with posttransplant TMA due to APSN recurrence that was resistant to plasmapheresis and explored the complement deposition and apoptotic and vascular cell markers on the sequential transplant biopsies. Treatment with eculizumab resulted in a rapid and dramatic improvement of the graft function in all three patients and in improvement of the TMA lesions within the graft. None of these patients had TMA flares after eculizumab was withdrawn. At the time of TMA diagnosis, immunofluorescence studies revealed intense C5b-9 and C4d depositions at the endothelial cell surface of the injured vessels. Moreover, C5b-9 colocalized with vessels exhibiting a high rate of apoptotic cells. Examination of sequential biopsies during eculizumab therapy showed that TMA lesions, C4d and apoptotic markers were rapidly cleared but the C5b-9 deposits persisted for several months as a footprint of the TMA. Finally, we noticed that complement inhibition did not prevent the development of the chronic vascular changes associated with APSN. Eculizumab seems to be an efficient method for treating severe forms of posttransplant TMA due to APSN recurrence. Terminal complement inhibition does not prevent the development of chronic APSN.


Assuntos
Anticorpos Monoclonais Humanizados/uso terapêutico , Síndrome Antifosfolipídica/complicações , Apoptose/efeitos dos fármacos , Complicações Pós-Operatórias , Microangiopatias Trombóticas/prevenção & controle , Doenças Vasculares/tratamento farmacológico , Adulto , Anticorpos Antifosfolipídeos/sangue , Síndrome Antifosfolipídica/terapia , Doença Crônica , Feminino , Imunofluorescência , Humanos , Depleção Linfocítica , Masculino , Plasmaferese , Prognóstico , Recidiva , Microangiopatias Trombóticas/etiologia , Microangiopatias Trombóticas/patologia , Doenças Vasculares/etiologia , Doenças Vasculares/patologia
17.
Transpl Infect Dis ; 15(3): E115-8, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23601080

RESUMO

Ochroconis gallopava is an emerging cause of mycosis in solid organ transplant recipients. Herein, we report a rare case of disseminated O. gallopava infection that involved lung, subcutaneous area, brain and peritoneum in a heart transplant recipient. Despite voriconazole therapy, the patient died 2 months after diagnosis.


Assuntos
Ascomicetos/patogenicidade , Transplante de Coração/efeitos adversos , Micoses/diagnóstico , Micoses/patologia , Antifúngicos/uso terapêutico , Ascomicetos/classificação , Ascomicetos/isolamento & purificação , Encéfalo/microbiologia , Encéfalo/patologia , Evolução Fatal , Humanos , Pulmão/microbiologia , Pulmão/patologia , Masculino , Pessoa de Meia-Idade , Micoses/tratamento farmacológico , Micoses/microbiologia , Peritônio/microbiologia , Peritônio/patologia , Pirimidinas/uso terapêutico , Triazóis/uso terapêutico , Voriconazol
18.
Nat Genet ; 19(3): 301-2, 1998 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-9662410

RESUMO

It is generally assumed that the male:female (M:F) ratio in patients with type 1 (insulin-dependent) diabetes mellitus (IDDM) is 1. A recent survey, however, revealed that high incidence countries (mainly European) have a high M:F ratio and low incidence ones (Asian and African) have a low M:F ratio. We have now analysed the M:F ratio according to genotype at the major locus, the major histocompatibility complex (MHC; IDDM1). There are two main IDDM1 susceptibility haplotypes, HLA-DR3 and -DR4, which are present in 95% of Caucasian cases. We report here that in medium/high incidence Caucasian populations from the United States of America, United Kingdom and Sardinia (1307 cases), the bias in male incidence is largely restricted to the DR3/X category of patients (X not = DR4) with a M:F ratio of 1.7 (P=9.3x10(-7)), compared with a ratio of 1.0 in the DR4/Y category (Y;DR3). This is additional evidence for significant heterogeneity between the aetiology of 'DR4-associated' and 'DR3-associated' diabetes. We analysed linkage of type 1 diabetes to chromosome X, and as expected, most of the linkage to Xp13-p11 was in the DR3/X affected sibpair families (n=97; peak multipoint MLS at DXS1068=3.5, P=2.7x10(-4); single point MLS=4.5, P=2.7x10(-5)). This is evidence for aetiological heterogeneity at the IDDM1/MHC locus and, therefore, in the search for non-MHC loci in type 1 diabetes, conditioning of linkage data by HLA type is advised.


Assuntos
Diabetes Mellitus Tipo 1/genética , Ligação Genética , Antígeno HLA-DR3/genética , Cromossomo X , Adolescente , Adulto , Feminino , Humanos , Masculino , Caracteres Sexuais
19.
Nat Genet ; 17(3): 350-2, 1997 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-9354805

RESUMO

The IDDM2 type 1 diabetes susceptibility locus was mapped to and identified as allelic variation at the insulin gene (INS) VNTR regulatory polymorphism. In Caucasians, INS VNTR alleles divide into two discrete size classes. Class I alleles (26 to 63 repeats) predispose in a recessive way to type 1 diabetes, while class III alleles (140 to more than 200 repeats) are dominantly protective. The protective effect may be explained by higher levels of class III VNTR-associated INS mRNA in thymus such that elevated levels of preproinsulin protein enhance immune tolerance to preproinsulin, a key autoantigen in type 1 diabetes pathogenesis. The mode of action of IDDM2 is complicated, however, by parent-of-origin effects and possible allelic heterogeneity within the two defined allele classes. We have now analysed transmission of specific VNTR alleles in 1,316 families and demonstrate that a particular class I allele does not predispose to disease when paternally inherited, suggestive of polymorphic imprinting. But this paternal effect is observed only when the father's untransmitted allele is a class III. This allelic interaction is reminiscent of epigenetic phenomena observed in plants (for example, paramutation; ref. 17) and in yeast (for example, trans-inactivation; ref. 18). If untransmitted chromosomes can have functional effects on the biological properties of transmitted chromosomes, the implications for human genetics and disease are potentially considerable.


Assuntos
Diabetes Mellitus Tipo 1/genética , Insulina/genética , Alelos , Estudos de Casos e Controles , Diabetes Mellitus Tipo 1/epidemiologia , Feminino , Variação Genética , Genética Populacional , Homozigoto , Humanos , Masculino
20.
Nat Genet ; 19(3): 297-300, 1998 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-9662409

RESUMO

Genetic analysis of a mouse model of major histocompatability complex (MHC)-associated autoimmune type 1 (insulin-dependent) diabetes mellitus (IDDM) has shown that the disease is caused by a combination of a major effect at the MHC and at least ten other susceptibility loci elsewhere in the genome. A genome-wide scan of 93 affected sibpair families (ASP) from the UK (UK93) indicated a similar genetic basis for human type 1 diabetes, with the major genetic component at the MHC locus (IDDM1) explaining 34% of the familial clustering of the disease (lambda(s)=2.5; refs 3,4). In the present report, we have analysed a further 263 multiplex families from the same population (UK263) to provide a total UK data set of 356 ASP families (UK356). Only four regions of the genome outside IDDM1/MHC, which was still the only major locus detected, were not excluded at lambda(s)=3 and lod=-2, of which two showed evidence of linkage: chromosome 10p13-p11 (maximum lod score (MLS)=4.7, P=3x10(-6), lambda(s)=1.56) and chromosome 16q22-16q24 (MLS=3.4, P=6.5x10(-5), lambda(s)=1.6). These and other novel regions, including chromosome 14q12-q21 and chromosome 19p13-19q13, could potentially harbour disease loci but confirmation and fine mapping cannot be pursued effectively using conventional linkage analysis. Instead, more powerful linkage disequilibrium-based and haplotype mapping approaches must be used; such data is already emerging for several type 1 diabetes loci detected initially by linkage.


Assuntos
Diabetes Mellitus Tipo 1/genética , Adolescente , Adulto , Mapeamento Cromossômico , Predisposição Genética para Doença , Humanos , Reino Unido
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA