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1.
J Viral Hepat ; 31(7): 391-403, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38654623

RESUMO

In Vietnam and the Philippines, viral hepatitis is the leading cause of cirrhosis and liver cancer. This study aims to understand the barriers and enablers of people receiving care for hepatitis B and C to support both countries' efforts to eliminate viral hepatitis as a public health threat by 2030. Retrospective, semi-structured interviews were conducted with a purposive, quota-based sample of 63 people living with hepatitis B or C in one province of Vietnam and one region of the Philippines. A rapid deductive approach to thematic analysis produced key findings among the three phases of care: (1) pre-awareness and testing, (2) linkage and treatment initiation and (3) ongoing treatment and recovery. The research found that participants followed five typical journeys, from a variety of entry points. Barriers during the pre-awareness and testing phase included limited awareness about hepatitis and its management, stigma and psychological impacts. Enablers included being familiar with the health system and/or patients benefiting from social connections within the health systems. During the linkage and treatment initiation phase, barriers included difficult physical access, complex navigation and inadequate counselling. In this phase, family support emerged as a critical enabler. During the ongoing treatment and recovery phase, the cost of care and socially and culturally informed perceptions of the disease and medication use were both barriers and enablers. Exploring peoples' journeys with hepatitis B and C in Vietnam and the Philippines revealed many similarities despite the different cultural and health system contexts. Insights from this study may help generate a contextualized, people-centred evidence base to inform the design and improvement of primary care services for hepatitis in both research sites.


Assuntos
Acessibilidade aos Serviços de Saúde , Humanos , Vietnã/epidemiologia , Filipinas/epidemiologia , Masculino , Feminino , Pessoa de Meia-Idade , Adulto , Estudos Retrospectivos , Idoso , Hepatite B , Entrevistas como Assunto , Adulto Jovem , Hepatite C/epidemiologia , Hepatite C/tratamento farmacológico
2.
ADMET DMPK ; 11(4): 551-560, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37937241

RESUMO

Background and Purpose: The utilization of doxorubicin (DOX) in clinal trials is also challenging owing to its adverse effects, including low oral bioavailability, generation of reactive oxygen species (ROS), cardiotoxicity, and epithelial barrier damage. Recently, scavenging of ROS reduced the cytotoxicity of DOX, suggesting a new approach for using DOX as an anticancer treatment. Thus, in this study, non-silica and silica redox nanoparticles (denoted as RNPN and siRNP, respectively) with ROS scavenging features have been designed to encapsulate DOX and reduce its cytotoxicity. Experimental Approach: DOX-loaded RNPN (DOX@RNPN) and DOX-loaded siRNP (DOX@siRNP) were prepared by co-dissolving DOX with RNPN and siRNP, respectively. The size and stability of nanoparticles were characterized by the dynamic light scattering system. Additionally, encapsulation efficiency, loading capacity, and release profile of DOX@RNPN and DOX@siRNP were identified by measuring the absorbance of DOX. Finally, the cytotoxicity of DOX@RNPN and DOX@siRNP against normal murine fibroblast cells (L929), human hepatocellular carcinoma cells (HepG2), and human breast cancer cells (MCF-7) were also investigated. Key results: The obtained result showed that RNPN exhibited a pH-sensitive character while silanol moieties improved the stability of siRNP in physiological conditions. DOX@RNPN and DOX@siRNP were formed at several tens of nanometers in diameter with narrow distribution. Moreover, DOX@siRNP stabilized under different pH buffers, especially gastric pH, and improved encapsulation of DOX owing to the addition of silanol groups. DOX@RNPN and DOX@siRNP maintained anticancer activity of DOX against HepG2, and MCF-7 cells, while their cytotoxicity on L929 cells was significantly reduced compared to free DOX treatment. Conclusion: DOX@RNPN and DOX@siRNP could effectively suppress the adverse effect of DOX, suggesting the potential to become promising nanomedicines for cancer treatments.

3.
Taiwan J Obstet Gynecol ; 61(6): 1009-1014, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36427965

RESUMO

OBJECTIVE: Hemophilia A (HA) is an X-linked recessive bleeding disease caused by a deficiency or dysfunction of blood coagulation factor VIII (FVIII). Available treatment to replenish the missing factor may not reach a good outcome for all patients because of potential complications that include the development of inhibitor antibodies directed against factor VIII. Therefore, the prevention of transmitting pathogenic mutations to the next generation is the best solution for this disease. Preimplantation genetic testing for a monogenic disorder (PGT-M) has become a standard method to prevent the transmission of monogenic heritable disease. The gold standard of the molecular technique used for PGT-M nowadays is the co-amplification of the polymorphic microsatellite linkage markers that use microsatellite DNA technique that overcomes the limitation of other methods. The important issue of this technique is the definition of markers that are specific for each allele on different loci. Each gene locus needs a characteristic design to allow accurate diagnosis that can be applied on PGT-M due to the limited quantity of DNA available. Here we present our study of four specific self-designed linked polymorphic markers applied on screening the embryos before implantation for hemophilia A families in Vietnam. MATERIAL AND METHODS: In this study, we investigated the feasibility of application and diagnostic value of 4 STR loci (FXS1108, DXS9897, F8int22, DXS9901) in the intragenic or neighbouring regions of the F8 gene. 35 hemophilia A families were recruited for STR analysis to define at least two characteristic heterologous markers for each family and 12 cases of pre-implantation genetic testing (PGT-M) for carrier mothers were performed. RESULT: All 4 of these loci (FXS1108, DXS9897, F8int22, DXS9901) were found practical and useful for preimplantation genetic testing (PGT-M). All 12 cases of PGT-M using the method had informative STR results and correct diagnosis was achieved. 9 out of the 12 mothers (75%) were implanted with 1-2 thawed embryos after the biopsy resulting in the birth of 5 healthy babies (55%). CONCLUSION: We conclude that specific 4 STR markers for rapid pre-implantation genetic testing of hemophilia A can be successfully applied with high confidence and accuracy in clinical settings. The results of the study provide solid evidence confirming that the microsatellite DNA technique is a highly reliable method, suitable for hemophilia A families wishing to determine carrier status or having healthy babies.


Assuntos
Hemofilia A , Diagnóstico Pré-Implantação , Gravidez , Feminino , Humanos , Hemofilia A/diagnóstico , Hemofilia A/genética , Diagnóstico Pré-Implantação/métodos , Testes Genéticos/métodos , Repetições de Microssatélites/genética , Alelos
4.
Case Rep Neurol ; 14(2): 237-244, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35815107

RESUMO

Stiff Person Syndrome (SPS) is an extremely rare neurological condition characterized by muscle stiffness and painful muscle spasms. The symptoms often progress slowly and can cause disability. Antibodies to glutamic acid decarboxylase (anti-GAD) have been reported in up to 80% of the classic type of SPS. Paraneoplastic syndrome comprises 5% of SPS cases. These patients present with different malignancies including lung, thymus, breast, colon, and lymph nodes. In this paper, we report a case of a 25-year-old Vietnamese female patient with SPS presenting with unusual clinical manifestations of sudden onset, rapidly progressive spinal, abdominal, and lower limb rigidity accompanied by painful spasms, autonomic disorders, and severe, multiple bone fractures. Serologic tests detected high-titer anti-GAD, combined with anti-SOX1 antibodies, suggesting paraneoplastic SPS. Intravenous immunoglobulin has been employed as the main treatment therapy, and the patient has had a complete remission.

5.
Toxics ; 10(6)2022 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-35736923

RESUMO

We investigated changes in some laboratory indices and the liver histology of chronic hepatitis patients who were exposed to dioxin. In 2014, we collected liver biopsy samples for histopathological examination from 33 chronic hepatitis patients living around the Da Nang Airbase, which is a dioxin-contaminated area due to the herbicide spraying in Vietnam. Dioxin exposure was measured by its levels in the blood. METAVIR classification was used to clarify the liver fibrosis stage. Laboratory tests included ten biochemical and six hematological indices that were measured in the blood. A regression linear model and binary logistic regression were used for data analysis. The observed alterations in the liver at the histological level mainly comprised hydropic degenerative hepatocytes, lymphocytes and polynuclear leukocytes surrounding the liver cells and granular and lipoic degeneration. In addition, increased TCDD levels were associated with increasing aminotransferase (AST), alanine aminotransferase, protein and total bilirubin levels and liver fibrosis stage. Similarly, increased TEQ-PCDD/Fs levels were associated with higher levels of AST and protein and liver fibrosis stage. In conclusion, dioxin exposure altered the liver histology and increased some biochemical marker indices and the liver fibrosis stage of chronic hepatitis patients living in dioxin-contaminated areas in Da Nang, Vietnam.

6.
Anal Methods ; 13(30): 3368-3378, 2021 08 14.
Artigo em Inglês | MEDLINE | ID: mdl-34250989

RESUMO

We present the first reported quantification of trace elements in plutonium via a portable laser-induced breakdown spectroscopy (LIBS) device and demonstrate the use of chemometric analysis to enhance the handheld device's sensitivity and precision. Quantification of trace elements such as iron and nickel in plutonium metal via LIBS is a challenging problem due to the complex nature of the plutonium optical emission spectra. While rapid analysis of plutonium alloys has been demonstrated using portable LIBS devices, such as the SciAps Z300, their detection limits for trace elements are severely constrained by their achievable pulse power and length, light collection optics, and detectors. In this paper, analytical methods are evaluated as a means to circumvent the detection constraints. Three chemometric methods often used in analytical spectroscopy are evaluated; principal component regression, partial least-squares regression, and artificial neural networks. These models are evaluated based on goodness-of-fit metrics, root mean-squared error, and their achievable limits of detection (LoDs). Partial least squares proved superior for determining content of iron and nickel in plutonium metal, yielding LoDs of 15 and 20 ppm, respectively. These results of identifying the undesirable trace elements in plutonium components are critical for applications such as fabricating radioisotope thermoelectric generators or nuclear fuel.


Assuntos
Plutônio , Oligoelementos , Ligas , Lasers , Aprendizado de Máquina , Análise Espectral , Oligoelementos/análise
7.
Am J Med Genet A ; 179(8): 1420-1422, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31077548

RESUMO

Acromesomelic dysplasias are rare skeletal disorders leading to severe short stature and abnormal skeletal morphology. Acromesomelic dysplasia Maroteaux-type is caused by homozygous or compound heterozygous pathogenic variants in NPR2 that encodes for natriuretic peptide receptor B. Here, we reported the first AMDM case in South East Asia and identified a novel pathogenic variant in NPR2 (c. 152T>C, p. (Leu51Pro)). Further analyses reveal the parents and two other family members were heterozygous for the variant. The clinical report highlights the importance of molecular genetic testing in diagnosing rare hereditable disease affecting skeletal abnormalities.


Assuntos
Doenças do Desenvolvimento Ósseo/genética , Osso e Ossos/metabolismo , Mutação , Receptores do Fator Natriurético Atrial/genética , Adulto , Doenças do Desenvolvimento Ósseo/diagnóstico por imagem , Doenças do Desenvolvimento Ósseo/patologia , Osso e Ossos/diagnóstico por imagem , Osso e Ossos/patologia , Criança , Pré-Escolar , Análise Mutacional de DNA , Feminino , Expressão Gênica , Testes Genéticos , Heterozigoto , Homozigoto , Humanos , Masculino , Linhagem , Fenótipo , Radiografia , Vietnã
8.
Sci Rep ; 9(1): 6203, 2019 04 17.
Artigo em Inglês | MEDLINE | ID: mdl-30996333

RESUMO

Bacteremia is a leading cause of death in sub-Saharan Africa where childhood mortality rates are the highest in the world. The early diagnosis of bacteremia and initiation of treatment saves lives, especially in high-disease burden areas. However, diagnosing bacteremia is challenging for clinicians, especially in children presenting with co-infections such as malaria and HIV. There is an urgent need for a rapid method for detecting bacteremia in pediatric patients with co-morbidities to inform treatment. In this manuscript, we have developed and clinically validated a novel method for the direct detection of amphiphilic pathogen biomarkers indicative of bacteremia, directly in aqueous blood, by mimicking innate immune recognition. Specifically, we have exploited the interaction of amphiphilic pathogen biomarkers such as lipopolysaccharides (LPS) from Gram-negative bacteria and lipoteichoic acids (LTA) from Gram-positive bacteria with host lipoprotein carriers in blood, in order to develop two tailored assays - lipoprotein capture and membrane insertion - for their direct detection. Our assays demonstrate a sensitivity of detection of 4 ng/mL for LPS and 2 ng/mL for LTA using a waveguide-based optical biosensor platform that was developed at LANL. In this manuscript, we also demonstrate the application of these methods for the detection of LPS in serum from pediatric patients with invasive Salmonella Typhimurium bacteremia (n = 7) and those with Staphylococcal bacteremia (n = 7) with 100% correlation with confirmatory culture. Taken together, these results demonstrate the significance of biochemistry in both our understanding of host-pathogen biology, and development of assay methodology, as well as demonstrate a potential new approach for the rapid, sensitive and accurate diagnosis of bacteremia at the point of need.


Assuntos
Bacteriemia/diagnóstico , Interações Hospedeiro-Patógeno , Lipopolissacarídeos/sangue , Programas de Rastreamento/métodos , Ácidos Teicoicos/sangue , Biomarcadores/sangue , Técnicas Biossensoriais/métodos , Criança , Comorbidade , Diagnóstico Precoce , Bactérias Gram-Negativas , Bactérias Gram-Positivas , Humanos , Imunidade Inata , Lipoproteínas/sangue , Pediatria/métodos
9.
Anal Sci ; 33(4): 457-460, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28392519

RESUMO

Early and rapid detection of bovine tuberculosis (bTB) is critical to controlling the spread of this disease in cattle and other animals. In this study, we demonstrate the development of an immunoassay for the direct detection of the bovine bTB biomarker, lipomannan (LM) in serum using a waveguide-based optical biosensor. We apply an ultra-sensitive detection strategy developed by our team, termed lipoprotein capture, that exploits the pull-down of high-density lipoprotein (HDL) nanodiscs from cattle blood that allows for the recovery and detection of associated LM. We also profile the change in the expression of these TB biomarkers as a function of time from a small set of samples collected from studies of bovine TB-infected cattle. We demonstrate for the first time the direct detection of bovine LM in serum, and clearly show that the biomarker is expressed in detectable concentrations during the entire course of the infection.


Assuntos
Análise Química do Sangue/métodos , Lipopolissacarídeos/sangue , Tuberculose Bovina/sangue , Animais , Bovinos , Imunoensaio
10.
Medicine (Baltimore) ; 95(27): e4099, 2016 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-27399106

RESUMO

There is scarce information regarding hospital-acquired infections (HAIs) among children in resource-constrained settings. This study aims to measure prevalence of HAIs in Vietnamese pediatric hospitals.Monthly point prevalence surveys (PPSs) in 6 pediatric intensive care units (ICUs) in 3 referral hospitals during 1 year.A total of 1363 cases (1143 children) were surveyed, 59.9% male, average age 11 months. Admission sources were: other hospital 49.3%, current hospital 36.5%, and community 15.3%. Reasons for admission were: infectious disease (66%), noninfectious (20.8%), and surgery/trauma (11.3%). Intubation rate was 47.8%, central venous catheter 29.4%, peripheral venous catheter 86.2%, urinary catheter 14.6%, and hemodialysis/filtration 1.7%. HAI was diagnosed in 33.1% of the cases: pneumonia (52.2%), septicemia (26.4%), surgical site infection (2%), and necrotizing enterocolitis (2%). Significant risk factors for HAI included age under 7 months, intubation and infection at admission. Microbiological findings were reported in 212 cases (43%) with 276 isolates: 50 Klebsiella pneumoniae, 46 Pseudomonas aeruginosa, and 39 Acinetobacter baumannii, with carbapenem resistance detected in 55%, 71%, and 65%, respectively. Staphylococcus aureus was cultured in 18 cases, with 81% methicillin-resistant Staphylococcus aureus. Most children (87.6%) received antibiotics, with an average of 1.6 antibiotics per case. Colistin was administered to 96 patients, 93% with HAI and 49% with culture confirmed carbapenem resistance.The high prevalence of HAI with carbapenem resistant gram-negative strains and common treatment with broad-spectrum antibiotics and colistin suggests that interventions are needed to prevent HAI and to optimize antibiotic use.


Assuntos
Infecção Hospitalar/epidemiologia , Infecção Hospitalar/microbiologia , Farmacorresistência Bacteriana , Infecções por Bactérias Gram-Negativas/epidemiologia , Infecções por Bactérias Gram-Negativas/microbiologia , Carbapenêmicos/farmacologia , Infecção Hospitalar/tratamento farmacológico , Feminino , Infecções por Bactérias Gram-Negativas/tratamento farmacológico , Hospitais Pediátricos , Humanos , Lactente , Unidades de Terapia Intensiva Pediátrica , Masculino , Prevalência , Vietnã/epidemiologia
11.
Influenza Other Respir Viruses ; 9(6): 315-322, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25980749

RESUMO

BACKGROUND: Influenza constitutes a leading cause of morbidity and mortality worldwide. There is limited information about the aetiology of infection presenting clinically as influenza in hospitalised adults and children in South-East Asia. Such data are important for future management of respiratory infections. OBJECTIVES: To describe the aetiology of infection presenting clinically as influenza in those hospitalised in South-East Asia. METHODS: Respiratory specimens archived from July 2008 to June 2009 from patients hospitalised with suspected influenza from Indonesia, Thailand and Vietnam were tested for respiratory viruses and atypical bacteria by polymerase chain reaction. RESULTS: A total of 1222 patients' samples were tested. Of 1222, 776 patients (63·5%) were under the age of 5. Viruses detected included rhinoviruses in 229 of 1222 patients (18·7%), bocaviruses in 200 (16·4%), respiratory syncytial viruses in 144 (11·8%), parainfluenza viruses in 140 (11·5%; PIV1: 32; PIV2: 12; PIV3: 71; PIV4: 25), adenovirus in 102 (8·4%), influenza viruses in 93 (7·6%; influenza A: 77; influenza B: 16) and coronaviruses in 23 (1·8%; OC43: 14; E229: 9). Bacterial pathogens were Mycoplasma pneumoniae (n = 33, 2·7%), Chlamydophila psittaci (n = 2), C. pneumoniae (n = 1), Bordetella pertussis (n = 1) and Legionella pneumophila (n = 2). Overall, in-hospital case fatality rate was 29 of 1222 (2·4%). CONCLUSION: Respiratory viruses were the most commonly detected pathogens in patients hospitalised with a clinical suspicion of influenza. Rhinovirus was the most frequently detected virus, and M. pneumoniae, the most common atypical bacterium. The low number of detected influenza viruses demonstrates a low benefit for empirical oseltamivir therapy, unless during an influenza outbreak.

12.
J Am Chem Soc ; 134(28): 11550-8, 2012 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-22775452

RESUMO

Rapid and precise screening of small genetic variations, such as single-nucleotide polymorphisms (SNPs), among an individual's genome is still an unmet challenge at point-of-care settings. One crucial step toward this goal is the development of discrimination probes that require no enzymatic reaction and are easy to use. Here we report a new type of fluorescent molecular probe, termed a chameleon NanoCluster Beacon (cNCB), that lights up into different colors upon binding SNP targets. NanoCluster Beacons (NCBs) are collections of a small number of Ag atoms templated on single-stranded DNA that fluoresce strongly when placed in proximity to particular DNA sequences, termed enhancers. Here we show the fluorescence emission color of a NCB can change substantially (a shift of 60-70 nm in the emission maximum) depending upon the alignment between the silver nanocluster and the DNA enhancer sequence. Chameleon NCBs exploit this color shift to directly detect SNPs, based on the fact that different SNPs produce a different alignment between the Ag nanocluster and the enhancer. This SNP detection method has been validated on all single-nucleotide substitution scenarios in three synthetic DNA targets, in six disease-related SNP targets, and in two clinical samples taken from patients with ovarian serous borderline tumors. Samples with single-nucleotide variations can be easily identified by the naked eye under UV excitation, making this method a reliable and low-cost assay with a simple readout format.


Assuntos
Fluorescência , Nanoestruturas , Polimorfismo Genético , Cor , Sondas Moleculares
13.
Biochemistry ; 51(26): 5293-9, 2012 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-22680405

RESUMO

Hydration is a key determinant of the folding, dynamics, and function of proteins. In this study, temperature-dependent Fourier transform infrared (FTIR) spectroscopy combined with singular value decomposition (SVD) and global fitting were used to investigate both the interaction of water with α-helical proteins and the cooperative thermal unfolding of these proteins. This methodology has been applied to an isolated α-helix (Fs peptide) and to globular α-helical proteins including the helical subdomain and full-length villin headpiece (HP36 and HP67). The results suggest a unique IR signature for the interaction of water with the helical amide carbonyl groups of the peptide backbone. The IR spectra indicate a weakening of the net hydrogen bond strength of water to the backbone carbonyls with increasing temperature. This weakening of the backbone solvation occurs as a discrete transition near the maximum of the temperature-dependent hydrophobic effect, not a continuous change with increasing temperature. Possible molecular origins of this effect are discussed with respect to previous molecular dynamics simulations of the temperature-dependent solvation of the helix backbone.


Assuntos
Amidas/química , Peptídeos/química , Água/química , Estrutura Secundária de Proteína , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura
14.
Haematologica ; 93(2): 224-31, 2008 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-18223281

RESUMO

BACKGROUND: Congenital afibrinogenemia is characterized by the absence of fibrinogen, a hexamer composed of two copies of three polypeptides, Aalpha. Bbeta and gamma. The disease is caused by mutations in one of the three fibrinogen-encoding genes, FGA, FGB and FGG. Among these, several mutations have been reported to specifically impair fibrinogen secretion. We previously showed that secretion-defective fibrinogen mutants are retained in a pre-Golgi compartment and demonstrated the importance of the homologous betaC and gammaC domains in secretion. Here our aim was to restore the secretion of these mutants and study the properties of the rescued mutant molecules. DESIGN AND METHODS: COS-7 cells were transfected and incubated with chemical chaperones or at low temperature. Clotting assays and plasmin digestion studies were performed to characterize secreted fibrinogen molecules. RESULTS: The secretion defect of two missense mutants but not that of late-truncating mutants could be partially corrected by incubating cells at 27 degrees C. By contrast, exposure of cells to chemical chaperones i.e. 4-phenylbutyrate, dimethyl sulfoxide or trimethylamine N-oxide had no effect. The mutants rescued at 27 degrees C were incorporated into fibrin clots and formed factor XIII-mediated gamma-gamma dimers in contrast to the dysfibrinogenemia Vlissingen/Frankfurt IV mutant, a negative control for these assays. However, plasmin digestion analyses revealed aberrant patterns for the mutants compared to normal fibrinogen. CONCLUSIONS: Low temperature can restore the secretion of a subset of mutant fibrinogen molecules demonstrating that therapeutic manipulation of the quality control pathway is feasible for afibrinogenemia even though functional assays suggested a non-native conformation for the mutant molecules analyzed.


Assuntos
Fibrinogênio/metabolismo , Complexo de Golgi/metabolismo , Mutação de Sentido Incorreto , Afibrinogenemia/genética , Afibrinogenemia/metabolismo , Animais , Células COS , Chlorocebus aethiops , Temperatura Baixa , Fator XIII/metabolismo , Fibrinolisina/metabolismo , Complexo de Golgi/genética , Humanos , Chaperonas Moleculares/farmacologia , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Transfecção/métodos
15.
Hum Mol Genet ; 14(21): 3271-80, 2005 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-16195396

RESUMO

Congenital afibrinogenemia is a rare bleeding disorder characterized by the absence in circulation of fibrinogen, a hexamer composed of two sets of three polypeptides (Aalpha, Bbeta and gamma). Each polypeptide is encoded by a distinct gene, FGA, FGB and FGG, all three clustered in a region of 50 kb on 4q31. A subset of afibrinogenemia mutations has been shown to specifically impair fibrinogen secretion, but the underlying molecular mechanisms remained to be elucidated. Here, we show that truncation of the seven most C-terminal residues (R455-Q461) of the Bbeta chain specifically inhibits fibrinogen secretion. Expression of additional mutants and structural modelling suggests that neither the last six residues nor R455 is crucial per se for secretion, but prevent protein misfolding by protecting hydrophobic residues in the betaC core. Immunofluorescence and immuno-electron microscopy studies indicate that secretion-impaired mutants are retained in a pre-Golgi compartment. In addition, expression of Bbeta, gamma and angiopoietin-2 chimeric molecules demonstrated that the betaC domain prevents the secretion of single chains and complexes, whereas the gammaC domain allows their secretion. Our data provide new insight into the mechanisms accounting for the quality control of fibrinogen secretion and confirm that mutant fibrinogen retention is one of the pathological mechanisms responsible for congenital afibrinogenemia.


Assuntos
Afibrinogenemia/genética , Fibrinogênio/genética , Fibrinogênio/metabolismo , Modelos Moleculares , Afibrinogenemia/congênito , Sequência de Aminoácidos , Animais , Western Blotting , Células COS , Chlorocebus aethiops , Primers do DNA , Imunofluorescência , Humanos , Microscopia Imunoeletrônica , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Mutação/genética , Dobramento de Proteína
16.
Biochemistry ; 43(12): 3582-9, 2004 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-15035628

RESUMO

Fast relaxation kinetics studies of the B-domain of staphylococcal protein A were performed to characterize the folding and unfolding of this small three-helix bundle protein. The relaxation kinetics were initiated using a laser-induced temperature jump and probed using time-resolved infrared spectroscopy. The kinetics monitored within the amide I' absorbance of the polypeptide backbone exhibit two distinct kinetics phases with nanosecond and microsecond relaxation times. The fast kinetics relaxation time is close to the diffusion limits placed on protein folding reactions. The fast kinetics phase is dominated by the relaxation of the solvated helix (nu = 1632 cm(-1)), which reports on the fast relaxation of the individual helices. The slow kinetics phase follows the cooperative relaxation of the native helical bundle core that is monitored by both solvated (nu = 1632 cm(-1)) and buried helical IR bands (nu = 1652 cm(-1)). The folding rates of the slow kinetics phase calculated over an extended temperature range indicate that the core formation of this protein follows a pathway that is energetically downhill. The unfolding rates are much more strongly temperature-dependent indicating an activated process with a large energy barrier. These results provide significant insight into the primary process of protein folding and suggest that fast formation of helices can drive the folding of helical proteins.


Assuntos
Fragmentos de Peptídeos/química , Dobramento de Proteína , Proteína Estafilocócica A/química , Amidas/química , Ligação de Hidrogênio , Cinética , Lasers , Modelos Químicos , Conformação Proteica , Desnaturação Proteica , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Espectroscopia de Infravermelho com Transformada de Fourier , Relação Estrutura-Atividade , Temperatura , Termodinâmica
17.
Brain Res Mol Brain Res ; 115(2): 93-103, 2003 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-12877980

RESUMO

LMO4 is a transcription regulator interacting with proteins involved, among else, in tumorigenesis. Its function in the nervous system, and particularly in the adult nervous system, has however still to be elucidated. We decided to modify its expression in a neuronal model, human SH-SY5Y neuroblastoma cells, by permanent transfection of sense or anti-sense Lmo4 cDNAs. Generated clones overexpressing the Lmo4 transcript in sense orientation tended to aggregate. They showed significantly reduced average number of neurites per cell and average neuritic length per cell. The opposite was observed with clones overexpressing the anti-sense Lmo4 transcript. Furthermore, selected clones were subjected to 72 h long-term treatments with retinoic acid and phorbol ester (TPA), two biochemicals known to stimulate differentiation of non-transfected SH-SY5Y cells and other neuroblastoma cells. Neuritogenesis occurred after retinoic acid stimulation in all cases. The inhibitory effect of sense Lmo4 RNA overexpression on neuritic outgrowth was indeed prevented. The protein kinase C activator TPA could not induce neuritogenesis in SH-SY5Y cells overexpressing sense Lmo4 RNA. Thus, sense Lmo4 RNA overexpression, not Lmo4 endogenous transcription, overrides the stimulatory effect of TPA upon neuritic outgrowth. We also showed that Lmo4-dependent neuritic retraction and outgrowth correspond to altered phosphorylation of cytoskeletal proteins. Overall, Lmo4 RNA overexpression interferes with neuritic outgrowth, whereas anti-sense Lmo4 RNA expression favors neuritogenesis in SH-SY5Y cells. Consequently, changes in Lmo4 RNA expression levels might alter the rate of neuritic outgrowth in the developing and adult nervous system.


Assuntos
Proteínas de Homeodomínio/fisiologia , Neuritos/fisiologia , Precursores de RNA/fisiologia , Fatores de Transcrição/fisiologia , Proteínas Adaptadoras de Transdução de Sinal , Antineoplásicos/farmacologia , Western Blotting/métodos , Carcinógenos/farmacologia , Agregação Celular/efeitos dos fármacos , Agregação Celular/genética , Agregação Celular/fisiologia , Diferenciação Celular/efeitos dos fármacos , Diferenciação Celular/fisiologia , Linhagem Celular , Clonagem Molecular , Proteínas do Citoesqueleto/metabolismo , Expressão Gênica/fisiologia , Proteínas de Homeodomínio/genética , Humanos , Proteínas com Domínio LIM , Modelos Neurológicos , Neuritos/efeitos dos fármacos , Neuroblastoma/patologia , Ésteres de Forbol/farmacologia , RNA Antissenso/metabolismo , RNA Mensageiro/biossíntese , Reação em Cadeia da Polimerase Via Transcriptase Reversa/métodos , Fatores de Transcrição/genética , Transfecção/métodos , Tretinoína/farmacologia , Células Tumorais Cultivadas
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