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1.
Forensic Sci Int ; 279: 122-129, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28863404

RESUMO

Throughout the course of a forensic investigation following an explosive attack, the identification and recovery of tissue fragments is of extreme importance. There are few universally accepted methods to achieve this end. This project aims to explore this issue through the examination of the spatial distribution of the tissue fragments resulting from an explosive event. To address this, a two stage pilot study was conducted: first, a series of controlled explosions on porcine carcases was undertaken. Second, the data produced from these explosions were used to chart the spatial distribution of the tissue debris. In the controlled explosions, 3kg military grade explosive was chosen to create the maximum amount of fragmentation; this level of explosive also prevented the complete disappearance of forensic evidence through evaporation. Additionally, the blast created by military grade explosive is highly powerful and would mean that the maximum possible distance was achieved and would therefore allow the recorded distances and pattern spread to be a guideline for forensic recovery of associated with an explosive amount of an unknown size and quality. A total station was employed to record the location of the resulting forensic evidence, with the collected data analysed using R Studio. The observed patterns suggested that the distribution of remains is fairly consistent in trials under similar environmental conditions. This indicates potential for some general guidelines for forensic evidence collection (for example, the distance from the explosion that a search should cover).


Assuntos
Traumatismos por Explosões , Explosões , Ciências Forenses/métodos , Análise Espacial , Animais , Modelos Animais , Projetos Piloto , Suínos
3.
Ann R Coll Surg Engl ; 99(3): 210-215, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27659373

RESUMO

INTRODUCTION Biliary-enteric anastomoses are performed for a range of indications and may result in early and late complications. The aim of this study was to assess the risk factors and management of anastomotic leak and stricture following biliary-enteric anastomosis. METHODS A retrospective analysis of the medical records of patients who underwent biliary-enteric anastomoses in a tertiary referral centre between 2000 and 2010 was performed. RESULTS Four hundred and sixty-two biliary-enteric anastomoses were performed. Of these, 347 (75%) were performed for malignant disease. Roux-en-Y hepaticojejunostomy or choledocho-jejunostomy were performed in 440 (95%) patients. Perioperative 30-day mortality was 6.5% (n=30). Seventeen patients had early bile leaks (3.7%) and 17 had late strictures (3.7%) at a median of 12 months. On univariable logistic regression analysis, younger age was a significant risk factor for biliary anastomotic leak. However, on multivariable analysis only biliary reconstruction following biliary injury (odds ratio [OR]=6.84; p=0.002) and anastomosis above the biliary confluence (OR=4.62; p=0.03) were significant. Younger age and biliary reconstruction following injury appeared to be significant risk factors for biliary strictures but multivariable analysis showed that only younger age was significant. CONCLUSIONS Biliary-enteric anastomoses have a low incidence of early and late complications. Biliary reconstruction following injury and a high anastomosis (above the confluence) are significant risk factors for anastomotic leak. Younger patients are significantly more likely to develop an anastomotic stricture over the longer term.


Assuntos
Doenças dos Ductos Biliares/epidemiologia , Coledocostomia , Ducto Colédoco/cirurgia , Ducto Hepático Comum/cirurgia , Complicações Pós-Operatórias/epidemiologia , Adolescente , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Ampola Hepatopancreática , Anastomose Cirúrgica , Fístula Anastomótica/epidemiologia , Neoplasias dos Ductos Biliares/cirurgia , Ductos Biliares/lesões , Procedimentos Cirúrgicos do Sistema Biliar , Carcinoma Ductal Pancreático/cirurgia , Colangiocarcinoma/cirurgia , Neoplasias do Ducto Colédoco/cirurgia , Constrição Patológica/epidemiologia , Bases de Dados Factuais , Feminino , Humanos , Jejunostomia , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Mortalidade , Análise Multivariada , Razão de Chances , Neoplasias Pancreáticas/cirurgia , Pancreatite Crônica/cirurgia , Estudos Retrospectivos , Centros de Atenção Terciária , Adulto Jovem
4.
Am J Perinatol ; 33(13): 1300-1305, 2016 11.
Artigo em Inglês | MEDLINE | ID: mdl-27487228

RESUMO

Objective This study aims to evaluate the association between prepregnancy body mass index (BMI) and adverse pregnancy outcomes in women with type 1 diabetes mellitus (DM). Methods This is a secondary analysis of a cohort of 426 pregnancies in women with type 1 DM recruited before 20 weeks gestation. Women were categorized according to prepregnancy BMI: low BMI (< 20 kg/m2), normal BMI (20 to < 25 kg/m2), and high BMI (≥ 25 kg/m2). The outcomes of interest were: spontaneous abortion (delivery < 20 weeks gestation); preeclampsia; emergent delivery for maternal indications (hypertension or placental abruption); and preterm delivery (< 37 weeks gestation). Analyses included proportional hazards and multiple logistic regression models with covariates: age, age at diagnosis of type 1 DM, previous spontaneous abortion, microvascular disease (nephropathy or retinopathy), and glycohemoglobin A1 concentrations. Results Low BMI was associated with preterm delivery. High BMI was associated with emergent delivery for maternal indications. Glycemic control as measured by glycohemoglobin A1 was associated with increased risk of spontaneous abortion, attenuating the association with low prepregnancy weight. Conclusion Prepregnancy BMI is a risk factor to be considered when caring for women with type 1 DM, in particular for preterm delivery (low BMI) and emergent delivery for maternal indications (high BMI).


Assuntos
Aborto Espontâneo/epidemiologia , Índice de Massa Corporal , Parto Obstétrico/estatística & dados numéricos , Diabetes Mellitus Tipo 1 , Pré-Eclâmpsia/epidemiologia , Gravidez em Diabéticas , Nascimento Prematuro/epidemiologia , Descolamento Prematuro da Placenta/terapia , Adulto , Peso Corporal , Diabetes Mellitus Tipo 1/sangue , Emergências/epidemiologia , Feminino , Hemoglobinas Glicadas/metabolismo , Humanos , Gravidez , Gravidez em Diabéticas/sangue , Estudos Prospectivos , Adulto Jovem
5.
Diabet Med ; 31(3): 332-40, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24308574

RESUMO

AIMS: Gestational diabetes is a common pregnancy complication affecting races/ethnicities disproportionally. Adult height, an indicator of both genetic and early-life factors, is inconsistently associated with gestational diabetes risk. We examined the association and whether it varies by races in a nationally representative US cohort. METHODS: Analyses were conducted among 135 861 pregnancies in the Consortium on Safe Labor, 5567 of which were diagnosed with gestational diabetes based on medical records review. Generalized estimating equations were used to estimate odds ratios (95% confidence intervals) of gestational diabetes, controlling for other risk factors including body weight. Additionally, a meta-analysis of 15 761 pregnancies with gestational diabetes and 205 828 without gestational diabetes was conducted to estimate the pooled mean difference in height between those with gestational diabetes and control subjects. RESULTS: Height was inversely associated with gestational diabetes risk across races/ethnicities, with the strongest association among Asians (P for interaction < 0.01). Comparing extreme quartiles (> 168 vs. < 157 cm), adjusted odds ratios (95% confidence intervals) were 0.18 (0.09-0.36) for Asians/Pacific Islanders, 0.33 (0.29-0.38) for non-Hispanic white women, 0.39 (0.31-0.51) for Hispanics and 0.59 (0.47-0.75) for non-Hispanic black women. Meta-analysis found women with gestational diabetes to be significantly shorter than others. CONCLUSIONS: Taller women are at lower risk of developing gestational diabetes, with the magnitude of association varying significantly across races/ethnicities.


Assuntos
Negro ou Afro-Americano/estatística & dados numéricos , Estatura/etnologia , Diabetes Gestacional/epidemiologia , Hispânico ou Latino/estatística & dados numéricos , População Branca/estatística & dados numéricos , Análise de Variância , Índice de Massa Corporal , Diabetes Gestacional/etnologia , Feminino , Humanos , Razão de Chances , Gravidez , Prevalência , Fatores de Risco , Estados Unidos/epidemiologia
6.
Diabetologia ; 56(6): 1263-71, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23571827

RESUMO

AIMS/HYPOTHESIS: The escalating rate of childhood obesity is a public health concern worldwide, with children in certain ethnic groups being disproportionately affected. Our objective was to examine the joint effects of pre-pregnancy adiposity, pregnancy weight gain and gestational diabetes (GDM) in relation to excess fetal growth and to identify susceptible races or ethnic populations. METHODS: The risk for delivery of a large-for-gestational-age (LGA) infant, specific to race and fetal sex, was evaluated in 105,985 pregnancies in the Consortium on Safe Labor from 2002-2008. Generalised estimating equations were used to estimate the risk for delivery of LGA infants. Joint effects were employed to evaluate the interplay of three risk factors. Models were stratified by racial group considering one, two or three factors (i.e. pre-pregnancy adiposity, pregnancy weight gain and GDM, with 0 factors as the reference group). RESULTS: Greater pre-pregnancy adiposity, pregnancy weight gain and GDM were independently associated with increased risk of giving birth to an LGA infant across all races (except GDM among non-Hispanic whites), in both underweight and normal-weight women. Among non-Hispanic white, non-Hispanic black and Hispanic women, the three-factor joint effect was associated with substantially increased odds of LGA (OR [95% CI] 11.27 [8.40, 15.11], 7.09 [4.81, 10.45] and 10.19 [6.84, 15.19], respectively). However, for Asian women the joint effect of all three factors (OR [95% CI] 5.14 [2.11, 12.50]) was approximately the same as any of the two factors. CONCLUSIONS/INTERPRETATION: GDM, pre-pregnancy obesity and excessive pregnancy weight gain were jointly associated with elevated risk of giving birth to an LGA infant and the effects varied by race. This suggests that those involved in public health efforts aimed at preventing LGA deliveries should consider variations in racial groups when devising effective strategies.


Assuntos
Peso ao Nascer , Diabetes Gestacional/diagnóstico , Diabetes Gestacional/etnologia , Obesidade/etnologia , Aumento de Peso , Adiposidade , Adulto , Negro ou Afro-Americano , Peso Corporal , Estudos de Coortes , Etnicidade , Feminino , Macrossomia Fetal/diagnóstico , Hispânico ou Latino , Humanos , Recém-Nascido , Masculino , Gravidez , Complicações na Gravidez , Fatores de Risco , Adulto Jovem
7.
Phys Rev Lett ; 108(24): 245004, 2012 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-23004283

RESUMO

Nonlinear electron trapping physics governs the onset and saturation of stimulated Raman scattering (SRS) in laser beams with many speckles. Hot electrons from intense speckles, produced during SRS daughter electron-plasma-wave bowing and filamentation, seed and enhance the growth of SRS in neighboring speckles by reducing Landau damping. Trapping-induced nonlinearity and speckle interaction through transport of hot electrons and back- and sidescattered SRS waves enable the system of speckles to self-organize and exhibit coherent, sub-ps SRS bursts with more than 100% instantaneous reflectivity, consistent with a SRS transverse coherence width much larger than a speckle width.

8.
Phys Rev Lett ; 107(11): 115002, 2011 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-22026679

RESUMO

Experimental data from the Trident Laser facility is presented showing quasimonoenergetic carbon ions from nm-scaled foil targets with an energy spread of as low as ±15% at 35 MeV. These results and high-resolution kinetic simulations show laser acceleration of quasimonoenergetic ion beams by the generation of ion solitons with circularly polarized laser pulses (500 fs, λ=1054 nm). The conversion efficiency into monoenergetic ions is increased by an order of magnitude compared with previous experimental results, representing an important step towards applications such as ion fast ignition.

9.
Phys Rev Lett ; 107(4): 045003, 2011 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-21867015

RESUMO

Breakout afterburner (BOA) laser-ion acceleration has been demonstrated for the first time in the laboratory. In the BOA, an initially solid-density target undergoes relativistically induced transparency, initiating a period of enhanced ion acceleration. First-ever kinetic simulations of the BOA in three dimensions show that the ion beam forms lobes in the direction orthogonal to laser polarization and propagation. Analytic theory presented for the electron dynamics in the laser ponderomotive field explains how azimuthal symmetry breaks even for a symmetric laser intensity profile; these results are consistent with recent experiments at the Trident laser facility.

10.
Case Rep Gastroenterol ; 5(1): 183-8, 2011 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-21552442

RESUMO

Common causes of chronic upper gastrointestinal bleeding include oesophageal varices, gastroduodenal ulcers and malignancy, and patients mostly present with iron deficiency type anaemia. We present the case of a 60-year-old lady who presented with iron deficiency anaemia and on investigation was found to have a large duodenal polyp requiring surgical excision. On histological examination, the polyp was revealed to be a lipoma. We review the recent literature and formulate a management plan for this rare entity.

11.
Phys Rev Lett ; 103(4): 045002, 2009 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-19659362

RESUMO

We report on the acceleration of ion beams from ultrathin diamondlike carbon foils of thickness 50, 30, and 10 nm irradiated by ultrahigh contrast laser pulses at intensities of approximately 7 x 10;{19} W/cm;{2}. An unprecedented maximum energy of 185 MeV (15 MeV/u) for fully ionized carbon atoms is observed at the optimum thickness of 30 nm. The enhanced acceleration is attributed to self-induced transparency, leading to strong volumetric heating of the classically overdense electron population in the bulk of the target. Our experimental results are supported by both particle-in-cell (PIC) simulations and an analytical model.

12.
J Perinatol ; 28(1): 48-54, 2008 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-18033306

RESUMO

OBJECTIVE: To determine the capillary partial pressure of carbon dioxide (PCO(2)) and room air transcutaneous hemoglobin saturation (RA SAT) at 36 weeks' postmenstrual age (PMA) in infants born with weight between 501 and 1250 g. STUDY DESIGN: Multicenter, prospective investigation with primary data collection within 72 h of 36 weeks PMA or discharge, whichever first. PCO(2) and RA SAT determinations were done at rest on infants not requiring mechanical ventilation or nasal continuous positive airway pressure (NCPAP). RESULT: A total of 220 infants were enrolled (mean gestational age 27.7 weeks, mean birthweight 951 g). In infants with traditionally defined chronic lung disease (CLD) compared to those without CLD, the mean PCO(2) was significantly higher (54 versus 45 mm Hg) and the median RA SAT significantly lower (<80 versus 97%). In infants with the new classification of bronchopulmonary dysplasia (BPD), there was a significant linear trend toward increasing PCO(2) with increasing severity of BPD (45, 47, 54 and 62 mm Hg in No, Mild, Moderate and Severe BPD). There was a significant linear trend toward decreasing RA SAT with increasing severity of BPD (97, 95 <80, <80% in No, Mild, Moderate and Severe BPD). CONCLUSION: Defining CLD as BPD based upon a RA SAT test is a more discriminate, objective method to categorize lung injury. PCO(2) is an objective measure of lung function that inversely correlates with RA SAT. These determinations done together at 36 weeks PMA may provide more precise and accurate estimates of lung injury that might allow for better understanding of pulmonary therapies and clearer comparison of BPD rates and severities among NICUs.


Assuntos
Displasia Broncopulmonar/fisiopatologia , Dióxido de Carbono/sangue , Recém-Nascido Prematuro , Fenômenos Fisiológicos Respiratórios , Gasometria , Displasia Broncopulmonar/sangue , Displasia Broncopulmonar/diagnóstico , Humanos , Recém-Nascido , Recém-Nascido de muito Baixo Peso/fisiologia , Unidades de Terapia Intensiva Neonatal , Oximetria
13.
Phys Rev Lett ; 98(3): 035002, 2007 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-17358690

RESUMO

We investigate the magnetic energy transfer from the fluid to kinetic scales and dissipation processes using three-dimensional fully kinetic particle-in-cell plasma simulations. The nonlinear evolution of a sheet pinch is studied where we show that it exhibits both fluid scale global relaxation and kinetic scale collisionless reconnection at multiple resonant surfaces. The interactions among collisionless tearing modes destroy the original flux surfaces and produce stochastic fields, along with generating sheets and filaments of intensified currents. In addition, the magnetic energy is transferred from the original shear length scale both to the large scales due to the global relaxation and to the smaller, kinetic scales for dissipation. The dissipation is dominated by the thermal or pressure effect in the generalized Ohm's law, and electrons are preferentially accelerated.

14.
Phys Rev Lett ; 99(26): 265004, 2007 Dec 31.
Artigo em Inglês | MEDLINE | ID: mdl-18233584

RESUMO

Stimulated Raman (SRS) and Brillouin scattering (SBS) are examined in the kinetic regime using particle-in-cell simulations. Wave front bowing of electron-plasma waves (ion-acoustic waves) from trapped particle nonlinear frequency shift is observed in the SRS (SBS) regime for the first time. Self-focusing from trapped particle modulational instability (TPMI) is shown to occur in 2D and 3D SRS simulations. The key physics of SRS saturation is identified as a combination of wave front bowing, TPMI, and self-focusing: Bowing marks the beginning of SRS saturation and self-focusing terminates SRS. Ion-acoustic wave bowing also contributes to SBS saturation. Velocity diffusion by transverse modes and rapid loss of hot electrons in regions of small transverse extent formed from self-focusing dissipate wave energy and increase Landau damping, despite trapping that reduces Landau damping initially.

15.
Br J Pharmacol ; 149(7): 880-7, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17031385

RESUMO

BACKGROUND AND PURPOSE: The ATP-gated P2X(7) receptor has been shown to play a role in several inflammatory processes, making it an attractive target for anti-inflammatory drug discovery. We have recently identified a novel set of cyclic imide compounds that inhibited P2X(7) receptor-mediated dye uptake in human macrophage THP-1 cells. In this study the actions and selectivity of one of these compounds, AZ11645373, were characterized. EXPERIMENTAL APPROACH: We measured membrane currents, calcium influx, and YOPRO-1 uptake from HEK cells expressing individual P2X receptors, and YOPRO1 uptake and interleukin-1beta release from THP-1 cells in response to ATP and the ATP analogue benzoylbenzoyl ATP (BzATP). KEY RESULTS: AZ11645373 up to 10 microM, had no agonist or antagonist actions on membrane currents due to P2X receptor activation at human P2X(1), rat P2X(2), human P2X(3), rat P2X(2/3), human P2X(4), or human P2X(5) receptors expressed in HEK cells. AZ11645373 inhibited human P2X(7) receptor responses in HEK cells in a non-surmountable manner with K (B) values ranging from 5 - 20 nM, with mean values not significantly different between assays. K (B) values were not altered by removing extracellular calcium and magnesium. ATP-evoked IL-1beta release from lipopolysaccharide-activated THP-1 cells was inhibited by AZ11645373, IC(50) = 90 nM. AZ11645373 was > 500-fold less effective at inhibiting rat P2X(7) receptor-mediated currents with less than 50% inhibition occurring at 10 microM. CONCLUSIONS AND IMPLICATIONS: AZ11645373 is a highly selective and potent antagonist at human but not rat P2X(7) receptors and will have much practical value in studies of human cells.


Assuntos
Anti-Inflamatórios/farmacologia , Imidas/farmacologia , Antagonistas do Receptor Purinérgico P2 , Tiazóis/farmacologia , Trifosfato de Adenosina/análogos & derivados , Trifosfato de Adenosina/farmacologia , Compostos de Anilina , Animais , Benzoxazóis , Sinalização do Cálcio/efeitos dos fármacos , Linhagem Celular , Relação Dose-Resposta a Droga , Corantes Fluorescentes , Humanos , Interleucina-1beta/metabolismo , Ativação do Canal Iônico/efeitos dos fármacos , Lipopolissacarídeos/farmacologia , Potenciais da Membrana/efeitos dos fármacos , Monócitos/efeitos dos fármacos , Monócitos/metabolismo , Técnicas de Patch-Clamp , Compostos de Quinolínio , Ratos , Receptores Purinérgicos P2/metabolismo , Receptores Purinérgicos P2X7 , Especificidade da Espécie , Tiazóis/química , Transfecção , Xantenos
16.
Bioorg Med Chem Lett ; 13(22): 4043-6, 2003 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-14592504

RESUMO

The synthesis and pharmacological evaluation of a new series of potent P2X(7) receptor antagonists is disclosed. The compounds inhibit BzATP-mediated pore formation in THP-1 cells. The distribution of the P2X(7) receptor in inflammatory cells, most notably the macrophage, mast cell and lymphocyte, suggests that P2X(7) antagonists have a significant role to play in the treatment of inflammatory disease.


Assuntos
Trifosfato de Adenosina/análogos & derivados , Trifosfato de Adenosina/síntese química , Antagonistas do Receptor Purinérgico P2 , Trifosfato de Adenosina/farmacologia , Linhagem Celular , Humanos , Cinética , Estrutura Molecular , Receptores Purinérgicos P2X7 , Relação Estrutura-Atividade
17.
Br J Biomed Sci ; 60(2): 71-4, 2003.
Artigo em Inglês | MEDLINE | ID: mdl-12866912

RESUMO

Laboratory confirmation of MRSA is important for the implementation of infection control; conventional screening culture methods take up to five days for confirmation. The purpose of this study is to ascertain the efficiency of three selective media for growth of methicillin-resistant Staphylococcus aureus (MRSA) before and after enrichment in salt broth, and to evaluate the Mastalex-MRSA latex agglutination kit for detection of methicillin resistance. Screening swabs were collected from 63 patients, yielding 125 S. aureus isolates and 40 coagulase-negative staphylococcus (CNS) isolates. Selective media used were mannitol salt agar (MSA), Baird-Parker agar with ciprofloxacin (BPC) and bromocresol purple (BCPA). Polymerase chain reaction (PCR) for mecA gene detection was used as the reference standard for evaluation of the Mastalex-MRSA assay, which was also evaluated on colonies of S. aureus from the selective media. No significant difference was found in efficiency of MRSA isolation among the selective media. Pre-enrichment in the salt broth did not enhance isolation of MRSA. Methicillin-sensitive S. aureus and CNS were significantly inhibited in all selective media (P<0.05). Only BPC significantly selected out methicillin-resistant CNS (P<0.01). Mastalex-MRSA was 97% specific and sensitive for the detection of MRSA. It was 65% sensitive and 100% specific in detecting methicillin resistance in CNS. In conclusion, all selective media performed equally well (MRSA isolation rate of approximately 80%). Mastalex-MRSA provided rapid and reliable detection of MRSA from selective media, reducing the time required for confirmation of this organism.


Assuntos
Resistência a Meticilina , Testes de Sensibilidade Microbiana/métodos , Staphylococcus aureus/efeitos dos fármacos , Testes de Aglutinação/métodos , Meios de Cultura , Humanos , Kit de Reagentes para Diagnóstico
18.
J Biol Chem ; 276(50): 47411-20, 2001 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-11592965

RESUMO

The 100-kDa "a" subunit of the vacuolar proton-translocating ATPase (V-ATPase) is encoded by two genes in yeast, VPH1 and STV1. The Vph1p-containing complex localizes to the vacuole, whereas the Stv1p-containing complex resides in some other intracellular compartment, suggesting that the a subunit contains information necessary for the correct targeting of the V-ATPase. We show that Stv1p localizes to a late Golgi compartment at steady state and cycles continuously via a prevacuolar endosome back to the Golgi. V-ATPase complexes containing Vph1p and Stv1p also differ in their assembly properties, coupling of proton transport to ATP hydrolysis, and dissociation in response to glucose depletion. To identify the regions of the a subunit that specify these different properties, chimeras were constructed containing the cytosolic amino-terminal domain of one isoform and the integral membrane, carboxyl-terminal domain from the other isoform. Like the Stv1p-containing complex, the V-ATPase complex containing the chimera with the amino-terminal domain of Stv1p localized to the Golgi and the complex did not dissociate in response to glucose depletion. Like the Vph1p-containing complex, the V-ATPase complex containing the chimera with the amino-terminal domain of Vph1p localized to the vacuole and the complex exhibited normal dissociation upon glucose withdrawal. Interestingly, the V-ATPase complex containing the chimera with the carboxyl-terminal domain of Vph1p exhibited a higher coupling of proton transport to ATP hydrolysis than the chimera containing the carboxyl-terminal domain of Stv1p. Our results suggest that whereas targeting and in vivo dissociation are controlled by sequences located in the amino-terminal domains of the subunit a isoforms, coupling efficiency is controlled by the carboxyl-terminal region.


Assuntos
Adenosina Trifosfatases/metabolismo , Prótons , ATPases Vacuolares Próton-Translocadoras/química , ATPases Vacuolares Próton-Translocadoras/metabolismo , Trifosfato de Adenosina/metabolismo , Motivos de Aminoácidos , Sequência de Aminoácidos , Western Blotting , Membrana Celular/metabolismo , Deleção de Genes , Glucose/metabolismo , Glucose/farmacologia , Complexo de Golgi/metabolismo , Hidrólise , Microscopia de Fluorescência , Dados de Sequência Molecular , Plasmídeos/metabolismo , Testes de Precipitina , Isoformas de Proteínas , Estrutura Terciária de Proteína , Proteínas Recombinantes de Fusão/metabolismo , Homologia de Sequência de Aminoácidos , ATPases Vacuolares Próton-Translocadoras/genética , Vacúolos/metabolismo , Leveduras/metabolismo
19.
Mol Biol Cell ; 12(6): 1737-49, 2001 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-11408581

RESUMO

Genes encoding chemokine receptor-like proteins have been found in herpes and poxviruses and implicated in viral pathogenesis. Here we describe the cellular distribution and trafficking of a human cytomegalovirus (HCMV) chemokine receptor encoded by the US28 gene, after transient and stable expression in transfected HeLa and Cos cells. Immunofluorescence staining indicated that this viral protein accumulated intracellularly in vesicular structures in the perinuclear region of the cell and showed overlap with markers for endocytic organelles. By immunogold electron microscopy US28 was seen mostly to localize to multivesicular endosomes. A minor portion of the protein (at most 20%) was also expressed at the cell surface. Antibody-feeding experiments indicated that cell surface US28 undergoes constitutive ligand-independent endocytosis. Biochemical analysis with the use of iodinated ligands showed that US28 was rapidly internalized. The high-affinity ligand of US28, the CX(3)C-chemokine fractalkine, reduced the steady-state levels of US28 at the cell surface, apparently by inhibiting the recycling of internalized receptor. Endocytosis and cycling of HCMV US28 could play a role in the sequestration of host chemokines, thereby modulating antiviral immune responses. In addition, the distribution of US28 mainly on endosomal membranes may allow it to be incorporated into the viral envelope during HCMV assembly.


Assuntos
Citomegalovirus/metabolismo , Receptores de Quimiocinas/biossíntese , Proteínas Virais/biossíntese , Animais , Western Blotting , Células CHO , Células COS , Membrana Celular/metabolismo , Quimiocina CX3CL1 , Quimiocinas CX3C/metabolismo , Cricetinae , DNA Complementar/metabolismo , Regulação para Baixo , Endocitose , Endossomos/metabolismo , Fibroblastos/metabolismo , Fibroblastos/virologia , Células HeLa , Humanos , Ligantes , Proteínas de Membrana/metabolismo , Microscopia Eletrônica , Microscopia de Fluorescência , Temperatura , Fatores de Tempo
20.
Mol Biol Cell ; 11(12): 4277-94, 2000 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-11102523

RESUMO

We show that the vacuolar protein sorting gene VPS44 is identical to NHX1, a gene that encodes a sodium/proton exchanger. The Saccharomyces cerevisiae protein Nhx1p shows high homology to mammalian sodium/proton exchangers of the NHE family. Nhx1p is thought to transport sodium ions into the prevacuole compartment in exchange for protons. Pulse-chase experiments show that approximately 35% of the newly synthesized soluble vacuolar protein carboxypeptidase Y is missorted in nhx1 delta cells, and is secreted from the cell. nhx1 delta cells accumulate late Golgi, prevacuole, and lysosome markers in an aberrant structure next to the vacuole, and late Golgi proteins are proteolytically cleaved more rapidly than in wild-type cells. Our results show that efficient transport out of the prevacuolar compartment requires Nhx1p, and that nhx1 delta cells exhibit phenotypes characteristic of the "class E" group of vps mutants. In addition, we show that Nhx1p is required for protein trafficking even in the absence of the vacuolar ATPase. Our analysis of Nhx1p provides the first evidence that a sodium/proton exchange protein is important for correct protein sorting, and that intraorganellar ion balance may be important for endosomal function in yeast.


Assuntos
Proteínas de Transporte/fisiologia , Proteínas de Transporte de Cátions , Canais de Cloreto , Endossomos/metabolismo , Transporte Proteico , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae/metabolismo , Trocadores de Sódio-Hidrogênio , ATPases Vacuolares Próton-Translocadoras , Sequência de Aminoácidos , Proteínas de Transporte/genética , Proteínas Fúngicas/fisiologia , Proteínas de Membrana/fisiologia , Modelos Biológicos , Dados de Sequência Molecular , Mutação , ATPases Translocadoras de Prótons/fisiologia , Saccharomyces cerevisiae/genética , Homologia de Sequência , Vacúolos/metabolismo
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