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1.
Parasit Vectors ; 15(1): 137, 2022 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-35449113

RESUMO

BACKGROUND: The primary disease vectors for dengue virus (DENV) transmission between humans are the mosquitoes Aedes aegypti and Aedes albopictus, with Ae. aegypti population size strongly correlated with DENV outbreaks. When a mosquito is infected with DENV, the virus migrates from the midgut to the salivary glands to complete the transmission cycle. How the virus crosses the hemocoel, resulting in systemic infection, is still unclear however. During viral infection and migration, the innate immune system is activated in defense. As part of cellular-mediated immunity, hemocytes are known to defend against bacteria and Plasmodium infection and may also participate in defending against DENV infection. Hemocytes are categorized into three cell types: prohemocytes, granulocytes, and oenocytoids. Here, we investigated which hemocytes can be infected by DENV and compare hemocyte infection between Ae. aegypti and Ae. albopictus. METHODS: Hemocytes were collected from Ae. aegypti and Ae. albopictus mosquitoes that were intrathoracically infected with DENV2-GFP. The collected hemocytes were then identified via Giemsa staining and examined microscopically for morphological differences and viral infection. RESULTS: All three types of hemocytes were infected by DENV, though the predominantly infected cell type was prohemocytes. In Ae. aegypti, the highest and lowest infection rates at 7 days post infection occurred in prohemocytes and granulocytes, respectively. Prohemocytes were also the primary infection target of DENV in Ae. albopictus, with similar infection rates across the other two hemocyte groups. The ratios of hemocyte composition did not differ significantly between non-infected and infected mosquitoes for either species. CONCLUSIONS: In this study, we showed that prohemocytes were the major type of hemocyte infected by DENV in both Ae. aegypti and Ae. albopictus. The infection rate of prohemocytes in Ae. albopictus was lower than that in Ae. aegypti, which may explain why systemic DENV infection in Ae. albopictus is less efficient than in Ae. aegypti and why Ae. albopictus is less correlated to dengue fever outbreaks. Future work in understanding the mechanisms behind these phenomena may help reduce arbovirus infection prevalence.


Assuntos
Aedes , Vírus da Dengue , Dengue , Animais , Humanos , Mosquitos Vetores , Glândulas Salivares
2.
Polymers (Basel) ; 12(1)2019 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-31861947

RESUMO

This study investigated a new category of transparent encapsulant materials for light-emitting diodes (LEDs). It comprised a phenyl group that contained siloxane-modified epoxy (SEP-Ph) hybridized with a cyclic tetrafunctional siloxane-modified epoxy (SEP-D4) with methylhexahydrophthalic anhydride (MHHPA) as a curing agent. The SEP-Ph/SEP-D4 = 0.5/0.5 (sample 3) and SEP-D4 (sample 4) could provide notably high optical transmittance (over 90% in the visible region), high-temperature discoloration resistance, low stress, and more crucially, noteworthy sulfurization resistance. The lumen flux retention of the SEP encapsulated surface mounted device LEDs remained between approximately 97% and 99% after a sulfurization test for 240 h. The obtained comprehensive optical, mechanical, and sulfurization resistance proved the validity and uniqueness of the present design concept with complementary physical and chemical characteristics.

4.
Nat Commun ; 6: 7138, 2015 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-26151821

RESUMO

Genetic susceptibility to colorectal cancer is caused by rare pathogenic mutations and common genetic variants that contribute to familial risk. Here we report the results of a two-stage association study with 18,299 cases of colorectal cancer and 19,656 controls, with follow-up of the most statistically significant genetic loci in 4,725 cases and 9,969 controls from two Asian consortia. We describe six new susceptibility loci reaching a genome-wide threshold of P<5.0E-08. These findings provide additional insight into the underlying biological mechanisms of colorectal cancer and demonstrate the scientific value of large consortia-based genetic epidemiology studies.


Assuntos
Neoplasias Colorretais/genética , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Estudos de Casos e Controles , Humanos , Razão de Chances , Polimorfismo de Nucleotídeo Único
5.
Ther Apher Dial ; 19(5): 486-90, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25944488

RESUMO

Our group has previously reported that excessive vascular access bleeding during dialysis treatment in stable hemodialysis (HD) patients was associated with anemia and may indicate poorer health. The association between excessive blood loss from access cannulation site and clinical outcomes was unknown. We hypothesized that excessive access bleeding may have an impact on all-cause and cardiovascular (CV) mortality in this population. We prospectively conducted an observational, longitudinal study of 360 HD patients. Excessive access bleeding was defined as at least an occurrence of blood loss greater than 4 mL per HD session during a study period of one month. During a median follow-up of 83 months, all-cause mortality and CV mortality were registered. Outcomes were analyzed by Kaplan-Meier and Cox proportional hazards regression analyses. A total of 118 (32.8%) participants died and 54 of these were from CV death. Using a multivariate Cox proportional hazards regression, access bleeding was found to be an independent predictor of all-cause mortality (HR 1.67, 95% CI 0.96-2.91, P = 0.070) but not for CV death (HR 1.53, 95% CI 0.88-2.68, P = 0.135). Our study identified that excessive access cannulation site bleeding could be a novel marker for increased risk of death in HD patients.


Assuntos
Doenças Cardiovasculares/mortalidade , Cateterismo/efeitos adversos , Hemorragia/etiologia , Diálise Renal , Feminino , Previsões , Humanos , Estimativa de Kaplan-Meier , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Modelos de Riscos Proporcionais , Estudos Prospectivos , Diálise Renal/efeitos adversos
6.
Cancer Epidemiol Biomarkers Prev ; 24(1): 65-72, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25342389

RESUMO

BACKGROUND: miRNAs act as post-transcriptional regulators of gene expression. Genetic variation in miRNA-encoding sequences or their corresponding binding sites may affect the fidelity of the miRNA-mRNA interaction and subsequently alter the risk of cancer development. METHODS: This study expanded the search for miRNA-related polymorphisms contributing to the etiology of colorectal cancer across the genome using a novel platform, the Axiom miRNA Target Site Genotyping Array (237,858 markers). After quality control, the study included 596 cases and 429 controls from the Molecular Epidemiology of Colorectal Cancer study, a population-based case-control study of colorectal cancer in northern Israel. The association between each marker and colorectal cancer status was examined assuming a log-additive genetic model using logistic regression adjusted for sex, age, and two principal components. RESULTS: Twenty-three markers had P values less than 5.0E-04, and the most statistically significant association involved rs2985 (chr6:34845648; intronic of UHRF1BP1; OR = 0.66; P = 3.7E-05). Furthermore, this study replicated a previously published risk locus, rs1051690, in the 3'-untranslated region of the insulin receptor gene INSR (OR = 1.38; P = 0.03), with strong evidence of differences in INSR gene expression by genotype. CONCLUSIONS: This study is the first to examine associations between genetic variation in miRNA target sites and colorectal cancer using a genome-wide approach. Functional studies to identify allele-specific effects on miRNA binding are needed to confirm the regulatory capacity of genetic variation to influence risk of colorectal cancer. IMPACT: This study demonstrates the potential for an miRNA-targeted genome-wide association study to identify candidate susceptibility loci and prioritize them for functional characterization.


Assuntos
Neoplasias Colorretais/genética , Idoso , Feminino , Humanos , Masculino , MicroRNAs , Polimorfismo Genético , Risco
7.
Carcinogenesis ; 35(11): 2512-9, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25023989

RESUMO

Only a fraction of colorectal cancer heritability is explained by known risk-conferring genetic variation. This study was designed to identify novel risk alleles in Europeans. We conducted a genome-wide association study (GWAS) meta-analysis of colorectal cancer in participants from a population-based case-control study in Israel (n = 1616 cases, 1329 controls) and a consortium study from the Colon Cancer Family Registry (n = 1977 cases, 999 controls). We used a two-stage (discovery-replication) GWAS design, followed by a joint meta-analysis. A combined analysis identified a novel susceptibility locus that reached genome-wide significance on chromosome 4q32.2 [rs35509282, risk allele = A (minor allele frequency = 0.09); odds ratio (OR) per risk allele = 1.53; P value = 8.2 × 10(-9); nearest gene = FSTL5]. The direction of the association was consistent across studies. In addition, we confirmed that 14 of 29 previously identified susceptibility variants were significantly associated with risk of colorectal cancer in this study. Genetic variation on chromosome 4q32.2 is significantly associated with risk of colorectal cancer in Ashkenazi Jews and Europeans in this study.


Assuntos
Carcinogênese , Neoplasias Colorretais/genética , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Idoso , Idoso de 80 Anos ou mais , Estudos de Casos e Controles , Cromossomos Humanos Par 4/genética , Neoplasias Colorretais/patologia , Etnicidade , Feminino , Frequência do Gene , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único , Fatores de Risco
8.
Ther Apher Dial ; 18(1): 51-6, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24499084

RESUMO

Blood loss from the access cannulation site during hemodialysis (HD) treatment is inevitable. Nevertheless, during HD, excessive blood loss from the cannulation site is not uncommon. The clinical characteristics associated with it and whether such blood loss could impact on patient outcomes is unknown. This pilot study aims to identify the prevalence and risk factors associated with excessive bleeding (≥ 4 mL/session) from dialysis access cannulation site during regular HD treatments. Stable end-stage renal disease patients receiving maintenance HD via arteriovenous fistula (AVF) or graft (AVG) were included in this study (N = 361). They were closely monitored for one month for the occurrence of excessive access bleeding during each HD session. A total of 4152 sessions of HD were performed during the study period and 143 patients (39.6%) had at least one episode of excessive bleeding from the vascular access (≥ 4 mL/session). Individuals experiencing excessive bleeding episodes had a significantly lower hemoglobin level, higher rate of diabetes, central venous stenosis, longer dialysis vintage, lower serum albumin level, longer hemostasis time and higher AVG and anti-platelet agent use (all P < 0.05). In the multivariable logistic regression model, longer dialysis vintage, central venous stenosis, lower hemoglobin level, and AVG usage were independently associated with occurrence of excessive access bleeding. AVG users also clustered with other risk factors for excessive access bleeding. Our study identified the novel associations between excessive cannulation site bleeding with dialysis vintage, anemia and AVG usage. The significance and impact of long-term chronic, intermittent bleeding from dialysis access should be further explored.


Assuntos
Cateterismo/métodos , Hemorragia/etiologia , Falência Renal Crônica/terapia , Diálise Renal/métodos , Idoso , Anemia/complicações , Anemia/epidemiologia , Derivação Arteriovenosa Cirúrgica/métodos , Feminino , Hemorragia/epidemiologia , Humanos , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Projetos Piloto , Prevalência , Fatores de Risco , Fatores de Tempo
9.
PLoS One ; 8(8): e71404, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23940749

RESUMO

BACKGROUND: Uremic pruritus is a common and intractable symptom in patients on chronic hemodialysis, but factors associated with the severity of pruritus remain unclear. This study aimed to explore the associations of metabolic factors and dialysis adequacy with the aggravation of pruritus. METHODS: We conducted a 5-year prospective cohort study on patients with maintenance hemodialysis. A visual analogue scale (VAS) was used to assess the intensity of pruritus. Patient demographic and clinical characteristics, laboratory parameters, dialysis adequacy (assessed by Kt/V), and pruritus intensity were recorded at baseline and follow-up. Change score analysis of the difference score of VAS between baseline and follow-up was performed using multiple linear regression models. The optimal threshold of Kt/V, which is associated with the aggravation of uremic pruritus, was determined by generalized additive models and receiver operating characteristic analysis. RESULTS: A total of 111 patients completed the study. Linear regression analysis showed that lower Kt/V and use of low-flux dialyzer were significantly associated with the aggravation of pruritus after adjusting for the baseline pruritus intensity and a variety of confounding factors. The optimal threshold value of Kt/V for pruritus was 1.5 suggested by both generalized additive models and receiver operating characteristic analysis. CONCLUSIONS: Hemodialysis with the target of Kt/V ≥1.5 and use of high-flux dialyzer may reduce the intensity of pruritus in patients on chronic hemodialysis. Further clinical trials are required to determine the optimal dialysis dose and regimen for uremic pruritus.


Assuntos
Metaboloma , Prurido/etiologia , Prurido/metabolismo , Diálise Renal/normas , Uremia/complicações , Uremia/metabolismo , Idoso , Estudos de Coortes , Feminino , Humanos , Masculino , Metaboloma/fisiologia , Pessoa de Meia-Idade , Prurido/epidemiologia , Projetos de Pesquisa , Índice de Gravidade de Doença , Uremia/epidemiologia
10.
J Clin Oncol ; 31(14): 1713-8, 2013 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-23530095

RESUMO

PURPOSE: Prostate cancer has been described as a component tumor of Lynch syndrome (LS), with tumors obtained from mutation carriers demonstrating the DNA mismatch repair deficiency phenotype. Previous studies quantifying prostate cancer risk in LS have provided conflicting results. METHODS: We examined cancer histories of probands and their first- through fourth-degree relatives for 198 independent mutation-positive LS families enrolled in two US familial cancer registries. Modified segregation analysis was used to calculate age-specific cumulative risk or penetrance estimates, with accompanying Wald-type CIs. Cumulative lifetime risks and hazard ratio (HR) estimates for prostate cancer were calculated and compared with those of the general population. RESULTS: Ninety-seven cases of prostate cancer were observed in 4,127 men. Median age at prostate cancer diagnosis was 65 years (range, 38 to 89 years), with 11.53% of affected individuals diagnosed before age 50 years. The cumulative risk of prostate cancer at ages 60 and 80 years was 6.30% (95% CI, 2.47 to 9.96) and 30.0% (95% CI, 16.54 to 41.30), as compared with the population risk of 2.59% and 17.84%, respectively. The overall prostate cancer HR among carriers was 1.99 (95% CI, 1.31 to 3.03). CONCLUSION: The cumulative lifetime risk of prostate cancer in individuals with LS is two-fold higher than in the general population and is slightly higher in carriers diagnosed before age 60 years (HR, 2.48; 95% CI, 1.34 to 4.59). These estimates are clinically valuable to quantify risk for both patients and providers.


Assuntos
Neoplasias Colorretais Hereditárias sem Polipose/genética , Reparo de Erro de Pareamento de DNA/genética , Heterozigoto , Neoplasias da Próstata/epidemiologia , Neoplasias da Próstata/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Predisposição Genética para Doença , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Razão de Chances , Penetrância , Risco , Estados Unidos/epidemiologia
11.
Cancer ; 117(8): 1640-8, 2011 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-21472711

RESUMO

BACKGROUND: Statins and nonsteroidal anti-inflammatory drugs (NSAIDs) are associated with reduced risk of colorectal cancer (CRC) in some studies. The objective of this study was to quantify the relative risk of inflammatory bowel disease (IBD) as a risk factor for CRC and to estimate whether this risk may be modified by long-term use of NSAIDs or statins. METHODS: The Molecular Epidemiology of Colorectal Cancer study is a population-based, case-control study of incident colorectal cancer in northern Israel and controls matched by age, sex, clinic, and ethnicity. Personal histories of IBD and medication use were measured by structured, in-person interview. The relative risk of IBD and effect modification by statins and NSAIDs were quantified by conditional and unconditional logistic regression. RESULTS: Among 1921 matched pairs of CRC cases and controls, a self-reported history of IBD was associated with a 1.9-fold increased risk of CRC (95% confidence interval [CI], 1.12-3.26). Long-term statin use was associated with a reduced risk of both IBD-associated CRC (odds ratio [OR] = 0.07; 95% CI, 0.01-0.78) and non-IBD CRC (OR = 0.49; 95% CI, 0.39-0.62). Stratified analysis suggested that statins may be more protective among those with IBD (ratio of OR = 0.14; 95% CI, 0.01-1.31; P = .51), although not statistically significant. NSAID use in patients with a history of IBD was suggestive of reduced risk of CRC but did not reach statistical significance (OR = 0.47; 95% CI, 0.12-1.86). CONCLUSIONS: The risk of CRC was elevated 1.9-fold in patients with IBD. Long-term statin use was associated with reduced risk of CRC in patients with IBD.


Assuntos
Anti-Inflamatórios não Esteroides/uso terapêutico , Neoplasias Colorretais/etiologia , Inibidores de Hidroximetilglutaril-CoA Redutases/uso terapêutico , Doenças Inflamatórias Intestinais/complicações , Doenças Inflamatórias Intestinais/tratamento farmacológico , Idoso , Neoplasias Colorretais/prevenção & controle , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Risco , Autorrelato
12.
Int J Evol Biol ; 2011: 937434, 2011 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-21350639

RESUMO

The global evolution and spread of Mycobacterium tuberculosis (MTB), one of the most successful bacterial pathogens, remain a mystery. Advances in molecular technology in the past decade now make it possible to understand MTB strain evolution and transmission in the context of human population migration. Taiwan is a relatively isolated island, serving as a mixing vessel over the past four centuries as colonization by different waves of ethnic groups occurred. By using mycobacterial tandem repeat sequences as genetic markers, the prevalence of MTB strains in Taiwan revealed an interesting association with historical migrations of different ethnic populations, thus providing a good model to explore the global evolution and spread of MTB.

13.
Genet Epidemiol ; 34(7): 756-68, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-20878717

RESUMO

Anticipation, manifested through decreasing age of onset or increased severity in successive generations, has been noted in several genetic diseases. Statistical methods for genetic anticipation range from a simple use of the paired t-test for age of onset restricted to affected parent-child pairs to a recently proposed random effects model which includes extended pedigree data and unaffected family members [Larsen et al., 2009]. A naive use of the paired t-test is biased for the simple reason that age of onset has to be less than the age at ascertainment (interview) for both affected parent and child, and this right truncation effect is more pronounced in children than in parents. In this study, we first review different statistical methods for testing genetic anticipation in affected parent-child pairs that address the issue of bias due to right truncation. Using affected parent-child pair data, we compare the paired t-test with the parametric conditional maximum likelihood approach of Huang and Vieland [1997] and the nonparametric approach of Rabinowitz and Yang [1999] in terms of Type I error and power under various simulation settings and departures from the modeling assumptions. We especially investigate the issue of multiplex ascertainment and its effect on the different methods. We then focus on exploring genetic anticipation in Lynch syndrome and analyze new data on the age of onset in affected parent-child pairs from families seen at the University of Michigan Cancer Genetics clinic with a mutation in one of the three main mismatch repair (MMR) genes. In contrast to the clinic-based population, we re-analyze data on a population-based Lynch syndrome cohort, derived from the Danish HNPCC-register. Both datasets indicate evidence of genetic anticipation in Lynch syndrome. We then expand our review to incorporate recently proposed statistical methods that consider family instead of affected pairs as the sampling unit. These prospective censored regression models offer additional flexibility to incorporate unaffected family members, familial correlation and other covariates into the analysis. An expanded dataset from the Danish HNPCC-register is analyzed by this alternative set of methods.


Assuntos
Antecipação Genética , Neoplasias Colorretais Hereditárias sem Polipose/genética , Simulação por Computador , Reparo de Erro de Pareamento de DNA/genética , Bases de Dados Genéticas , Feminino , Humanos , Masculino , Modelos Genéticos , Modelos Estatísticos , Epidemiologia Molecular , Mutação , Linhagem , Modelos de Riscos Proporcionais , Análise de Regressão
14.
Intervirology ; 53(6): 394-401, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-20606461

RESUMO

BACKGROUND: Enterovirus (EV) 71 is an important pathogen causing death in children under 5 years of age worldwide. However, the core pathogenesis remains elusive. We reveal that the protein expression level of vascular endothelial growth factor (VEGF) in EV71 patients was 2-fold higher than in normal controls. However, the origin of VEGF in EV71-infected patients remains unclear. METHODS: VEGF mRNA and protein expression in four EV71-infected cell lines was evaluated by RT-PCR, ELISA and Western blotting. RESULTS: We found that only mRNA expression of VEGF was increased in the infected cells. Intra- and extracellular VEGF protein expression was decreased or unchanged in the four infected cell lines compared with the uninfected and inactivated EV71-infected cells. CONCLUSIONS: Our data reveal that EV71 infection of four human cell lines induced VEGF mRNA expression but did not induce VEGF protein expression in the infected cells. Therefore, the increased VEGF protein expression in EV71-infected patients may be due to the influence of surrounding non-infected cells following stimulation of proinflammatory cytokines secreted from the infected cells.


Assuntos
Enterovirus Humano A/patogenicidade , Infecções por Enterovirus/patologia , Infecções por Enterovirus/virologia , Expressão Gênica , Fator A de Crescimento do Endotélio Vascular/biossíntese , Western Blotting , Linhagem Celular , Enterovirus Humano A/isolamento & purificação , Ensaio de Imunoadsorção Enzimática , Humanos , Lactente , RNA Mensageiro/biossíntese , Reação em Cadeia da Polimerase Via Transcriptase Reversa
15.
Breast Cancer Res Treat ; 124(2): 459-65, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-20349131

RESUMO

PTEN Hamartoma Tumor Syndrome (PHTS) is often recognized by the presence of macrocephaly and associated mucocutaneous features, and is notable for a profound predisposition to breast and thyroid cancers. Head circumference (HC) is rarely measured when evaluating women at high risk for breast cancer, but may offer insight into characterizing cancer risk. Patients enrolled in the University of Michigan Cancer Genetics registry for breast cancer evaluation were analyzed for personal and family history of cancer and features of PHTS. This group of women was compared to all women who had undergone PTEN testing and whether or not they met clinical criteria for PHTS. Among the 164 women referred for breast cancer risk evaluation, a statistically significant difference in mean HC was found between women who did (57.3 cm) and did not (55.4 cm) meet clinical criteria for PHTS with both values below the established threshold for macrocephaly (58 cm). The sensitivity and specificity of macrocephaly for the presence of a PTEN mutation were 100 and 53%, respectively, among the 28 women tested. The positive predictive value was 14%. PTEN mutation positive and PTEN mutation negative women were not well differentiated by PHTS clinical criteria (P = 0.2348). The high sensitivity of HC suggests that this simple measure can improve the detection of unrecognized patients with PHTS. Measuring HC is a useful clinical feature, but is insufficient as a singular screening tool for PHTS. Even in a high risk population, the PPV of this test is low. Diagnosis of this important genetic syndrome still relies heavily on detailed history and full physical exam.


Assuntos
Neoplasias da Mama/genética , Cefalometria , Síndrome do Hamartoma Múltiplo/diagnóstico , Cabeça/patologia , Programas de Rastreamento/métodos , PTEN Fosfo-Hidrolase/genética , Neoplasias da Mama/patologia , Distribuição de Qui-Quadrado , Feminino , Predisposição Genética para Doença , Testes Genéticos , Síndrome do Hamartoma Múltiplo/genética , Síndrome do Hamartoma Múltiplo/patologia , Humanos , Michigan , Pessoa de Meia-Idade , Mutação , Linhagem , Fenótipo , Valor Preditivo dos Testes , Sistema de Registros , Medição de Risco , Fatores de Risco , Sensibilidade e Especificidade
16.
J Virol ; 84(1): 59-75, 2010 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-19793805

RESUMO

The molecular basis for localization of the human immunodeficiency virus type 1 envelope glycoprotein (Env) in detergent-resistant membranes (DRMs), also called lipid rafts, still remains unclear. The C-terminal cytoplasmic tail of gp41 contains three membrane-interacting, amphipathic alpha-helical sequences, termed lentivirus lytic peptide 2 (LLP-2), LLP-3, and LLP-1, in that order. Here we identify determinants in the cytoplasmic tail which are crucial for Env's association with Triton X-100-resistant rafts. Truncations of LLP-1 greatly reduced Env localization in lipid rafts, and the property of Gag-independent gp41 localization in rafts was conserved among different strains. Analyses of mutants containing single deletions or substitutions in LLP-1 showed that the alpha-helical structure of the LLP-1 hydrophobic face has a more-critical role in Env-raft associations than that of the hydrophilic face. With the exception of a Pro substitution for Val-833, all Pro substitution and charge-inverting mutants showed wild-type virus-like one-cycle viral infectivity, replication kinetics, and Env incorporation into the virus. The intracellular localization and cell surface expression of mutants not localized in lipid rafts, such as the TM844, TM813, 829P, and 843P mutants, were apparently normal compared to those of wild-type Env. Cytoplasmic subdomain targeting analyses revealed that the sequence spanning LLP-3 and LLP-1 could target a cytoplasmic reporter protein to DRMs. Mutations of LLP-1 that affected Env association with lipid rafts also disrupted the DRM-targeting ability of the LLP-3/LLP-1 sequence. Our results clearly demonstrate that LLP motifs located in the C-terminal cytoplasmic tail of gp41 harbor Triton X-100-resistant raft association determinants.


Assuntos
Proteína gp41 do Envelope de HIV/metabolismo , Microdomínios da Membrana/metabolismo , Fragmentos de Peptídeos/metabolismo , Motivos de Aminoácidos , Sítios de Ligação , Citoplasma , Proteína gp41 do Envelope de HIV/genética , Humanos , Mutação , Octoxinol/farmacologia , Fragmentos de Peptídeos/genética , Ligação Proteica
17.
J Med Virol ; 81(7): 1241-52, 2009 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-19475621

RESUMO

Enterovirus 71 (EV71) is an important pathogen causing death in children under 5 years old worldwide. However, the underlying pathogenesis remains unclear. This study reveals that EV71 infection in rhabdomyosarcoma (RD) and neuroblastoma (SK-N-SH) cells stimulated the autophagic process, which was demonstrated by an increase of punctate GFP-microtubule-associated protein 1 light chain 3 (GFP-LC3), the level of autophagosome-bound LC3-II protein and double-membrane autophagosome formation. EV71-induced autophagy benefited EV71 replication, which was confirmed by the autophagic inducer rapamycin and the inhibitor 3-methyladenine. Signaling pathway investigation revealed that the decreased expression of phosphorylated mTOR and phosphorylated p70S6K is involved in EV71-induced autophagy in a cell-specific manner. The expression of phosphorylated extracellular signal-regulated kinase (Erk) was suppressed consistently in EV71-infected cells. However it did not participate in the autophagic response of the cell. Other signaling pathway molecules, such as Erk, PI3K/Akt, Bcl-2, BNIP3, and Beclin-1 were not affected by infection with EV71. Electron microscopy showed co-localization of autophagosome-like vesicles with either EV71-VP1 or LC3 protein in neurons of the cervical spinal cord in ICR mice infected with EV71. In conclusion, EV71 infection triggered autophagic flux and induced autophagosome formation both in vitro and in vivo. Autophagy induced by EV71 is beneficial for viral replication. Understanding the role of autophagy induced by EV71 in vitro and the formation of autophagosome-like vesicle in vivo provide new insights into the pathogenesis of EV71 infection.


Assuntos
Autofagia , Enterovirus Humano A/fisiologia , Replicação Viral , Animais , Linhagem Celular , Pré-Escolar , Vesículas Citoplasmáticas/química , Vesículas Citoplasmáticas/ultraestrutura , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Humanos , Lactente , Camundongos , Camundongos Endogâmicos ICR , Microscopia Imunoeletrônica , Neurônios/química , Neurônios/ultraestrutura , Proteínas Quinases/metabolismo , Proteínas Quinases S6 Ribossômicas 70-kDa/metabolismo , Serina-Treonina Quinases TOR , Proteínas Virais/análise
18.
J Virol ; 83(2): 870-83, 2009 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-18987155

RESUMO

The highly conserved LWYIK motif located immediately proximal to the membrane-spanning domain of the gp41 transmembrane protein of human immunodeficiency virus type 1 has been proposed as being important for the surface envelope (Env) glycoprotein's association with lipid rafts and gp41-mediated membrane fusion. Here we employed substitution and deletion mutagenesis to understand the role of this motif in the virus life cycle. None of the mutants examined affected the synthesis, precursor processing, CD4 binding, oligomerization, or cell surface expression of the Env, nor did they alter Env incorporation into the virus. All of the mutants, particularly the DeltaYI, DeltaIK, and DeltaLWYIK mutants, in which the indicated residues were deleted, exhibited greatly reduced one-cycle viral replication and the Env trans-complementation ability. All of these deletion mutant proteins were still localized in the lipid rafts. With the exception of the Trp-to-Ala (WA) mutant, which exhibited reduced viral infectivity albeit with normal membrane fusion, all mutants displayed loss of some or almost all of the membrane fusion ability. Although these deletion mutants partially inhibited in trans wild-type (WT) Env-mediated fusion, they were more effective in dominantly interfering with WT Env-mediated viral entry when coexpressed with the WT Env, implying a role of this motif in postfusion events as well. Both T20 and L43L peptides derived from the two gp41 extracellular C- and N-terminal alpha-helical heptad repeats, respectively, inhibited WT and DeltaLWYIK Env-mediated viral entry with comparable efficacies. Biotin-tagged T20 effectively captured both the fusion-active, prehairpin intermediates of WT and mutant gp41 upon CD4 activation. Env without the deletion of the LWYIK motif still effectively mediated lipid mixing but inhibited content mixing. Our study demonstrates that the immediate membrane-proximal LWYIK motif acts as a unique and distinct determinant located in the gp41 C-terminal ectodomain by promoting enlargement of fusion pores and postfusion activities.


Assuntos
Proteína gp41 do Envelope de HIV/metabolismo , HIV-1/fisiologia , Replicação Viral , Motivos de Aminoácidos , Substituição de Aminoácidos/genética , Linhagem Celular , Proteína gp41 do Envelope de HIV/genética , Humanos , Mutagênese Sítio-Dirigida , Deleção de Sequência
19.
Am J Surg Pathol ; 33(1): 126-33, 2009 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-18830122

RESUMO

Identification of microsatellite unstable (MSI-H) colorectal cancers (CRCs) is important not only for the identification of hereditary nonpolyposis colorectal cancer syndrome but also because MSI-H CRCs have a better prognosis and may respond differently to 5-fluorouracil-based chemotherapy. We present 2 nearly equivalent logistic regression models for clinical use that predict microsatellite instability based on the review of 1649 CRCs from patients of all ages collected in a population-based case control study in northern Israel. One hundred ninety-eight of these 1649 tumors demonstrated a high degree of microsatellite instability (12%). Multivariate analysis found that >2 tumor-infiltrating lymphocyte (TIL) cells per high-powered field, the lack of dirty necrosis, the presence of a Crohn-like reaction, right-sided location, any mucinous differentiation (mucinous or focally mucinous) and well or poor differentiation, and age less than 50 were all independent predictors of MSI-H. We developed 2 logistic regression models that differ only by the statistical approach used to analyze the number of TIL cells per high-powered field, where the slightly more accurate (and complex) model uses the log of the total number of TIL cells. The simpler clinical model uses a cut-off of 2>TIL cells per high-powered field. The accuracy of both models is high, with an 85.4% versus 85.0% probability of correctly classifying tumors as MSI-H. By employing the simpler model, pathologists can predict the likelihood of microsatellite instability by compiling the MSI probability score (Table 4 and Fig. 1) from simple histologic and clinical data available during sign-out. Our model shows that approximately 43% of CRCs have a MSI probability score of 1 or less and hence have little likelihood (<3%) of being MSI-H. Although this model is not perfect in predicting microsatellite instability, its use could improve the efficiency of expensive diagnostic testing.


Assuntos
Adenocarcinoma/genética , Adenocarcinoma/patologia , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Instabilidade de Microssatélites , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Área Sob a Curva , Feminino , Humanos , Linfócitos do Interstício Tumoral/patologia , Masculino , Pessoa de Meia-Idade , Curva ROC , Análise de Regressão , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Sensibilidade e Especificidade
20.
Langmuir ; 23(24): 12086-95, 2007 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-17963412

RESUMO

Stable amorphous calcium carbonate (ACC) composite particle with a size-controlled monodispersed sphere was obtained by a new simple carbonate controlled-addition method by using poly(acrylic acid) (PAA) (Mw = 5000), in which an aqueous ammonium carbonate solution was added into an aqueous solution of PAA and CaCl2 with a different time period. The obtained ACC composite products consist of about 50 wt % of ACC, 30 wt % of PAA, and H2O. Average particle sizes of the ACC spheres increased from (1.8 +/- 0.4) x 102 to (5.5 +/- 1.2) x 102 nm with an increase of the complexation time of the PAA-CaCl2 solution from 3 min to 24 h, respectively. The ACC formed from the complexation time for 3 min was stable for 10 days with gentle stirring as well as 3 months under a quiescent condition in the aqueous solution. Moreover, the ACC was also stable at 400 degrees C. Stability of the amorphous phase decreased with an increase of the complexation time of the PAA-CaCl2 solution. No ACC was obtained when the lower molar mass PAAs (Mw = 1200 and 2100) were used. In the higher molar mass case (Mw = 25 000), a mixture of the amorphous phase and vaterite and calcite crystalline product was produced. The present results demonstrate that the interaction and the reaction kinetics of the PAA-Ca2+-H2O complex play an important role in the mineralization of CaCO3.


Assuntos
Carbonato de Cálcio/química , Minerais/química , Ácidos Polimetacrílicos/química , Água/química , Cloreto de Cálcio/química , Cristalização , Microscopia Eletrônica de Varredura , Peso Molecular , Soluções/química , Espectroscopia de Infravermelho com Transformada de Fourier , Propriedades de Superfície , Temperatura , Difração de Raios X
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