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1.
J Safety Res ; 82: 221-232, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-36031249

RESUMO

INTRODUCTION: Physical activity associated with active transport modes such as bicycling has major health benefits and can help to reduce health concerns related to sedentary lifestyles, such as cardiovascular disease, Type II diabetes, and obesity, as well as risks of colon and breast cancer, high blood pressure, lipid disorders, osteoporosis, depression, and anxiety. However, as a vulnerable user group, bicyclists experience negative health impacts of transportation policies and infrastructure, such as traffic crashes and exposure to air and noise pollution that is disproportionately distributed within low-income and underserved areas. METHOD: This study used aggregated (block-group) bicyclist crash data from Harris County, Texas, to analyze how various equity measures are associated with both fatal and injury (FI) and no injury (property damage only) bicyclist crashes that occurred from 2010 to 2017. We used Bayesian bivariate copula-based random effects regression analysis to evaluate these associations. In contrast to more traditional univariate analysis, this novel methodology can consider the effects of factors of interest across different severity levels or crash types to fully understand their effects and how they may differ across categories. RESULTS: The analysis results indicate that the bicyclist exposure, vehicle exposure, population demographics, population density, the percentage of African-Americans, and households below the poverty level are associated with both FI and PDO bicyclist crashes. CONCLUSIONS: Although more location and context-specific analyses are required, this study's overall results once again conform with the findings and assumptions in bicycling safety literature that the low-income and racially diverse communities are prone to experience more bicyclist crashes. PRACTICAL APPLICATIONS: The findings of this study may have implications for future transportation and planning policies. These findings can be used to guide the policies and strategies targeting the elimination of inequity in transportation-related health concerns.


Assuntos
Acidentes de Trânsito , Diabetes Mellitus Tipo 2 , Teorema de Bayes , Ciclismo , Humanos , Meios de Transporte
2.
Patient ; 14(5): 673-685, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-33840079

RESUMO

BACKGROUND: Lipodystrophy comprises a group of conditions characterized by loss of functional adipose tissue, resulting in severe metabolic complications and a complex range of symptoms. OBJECTIVE: This study sought to gain a holistic understanding of the impact of congenital or non-human immunodeficiency virus acquired lipodystrophies on the quality of life of patients and their caregivers and to capture the impact of lipodystrophy on quality of life using a standard instrument. METHODS: Ten patients with lipodystrophies and five caregivers from the USA and UK were recruited through convenience sampling and interviewed using a semi-structured questionnaire containing open-ended questions about disease symptoms and attributes and numerical rating scales to prompt discussion of symptom prevalence and impact. After the interview, participants filled out the 36-Item Short Form (SF-36) survey instrument. Conventional conceptual content analysis methods were used to analyze the anonymized transcripts. RESULTS: Four concepts were developed: diagnostic journey and symptom management, burden of disease, healthcare resource utilization, and support and advocacy. Participants described lengthy diagnostic journeys and frequent interactions with healthcare systems. Many participants became experts on lipodystrophy through the diagnostic journey and described difficulties accessing effective treatment, even after diagnosis. Both patients and caregivers emphasized the ongoing burden of living with lipodystrophy and the accompanying sense of isolation. Participants turned to disease-specific support groups to cope, engaging in knowledge sharing with other patients and caregivers and developing friendships based on shared experiences. Ten participants completed the SF-36, with a mean (standard deviation) SF-36 score of 0.6 (0.2). CONCLUSIONS: Currently, there are no qualitative studies that describe the experiences of patients with lipodystrophy and their caregivers. While additional research is needed, educational work like this study is a promising first step that could lead to early diagnosis and access to treatment and support.


Assuntos
Cuidadores , Lipodistrofia , Humanos , Cuidados Paliativos , Pesquisa Qualitativa , Qualidade de Vida
3.
J Pain Palliat Care Pharmacother ; 35(1): 1-6, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33125303

RESUMO

Erenumab is a monoclonal antibody that mediates calcitonin-gene-related peptide (CGRP), a pro-inflammatory polypeptide implicated in migraine pathology, by targeting its receptor. To date, no clinical trial has evaluated combination therapy with both erenumab and onabotulinumtoxinA therapy for the treatment of chronic migraine. We conducted a retrospective chart review of 78 patients to investigate if the addition of erenumab to patients with chronic migraines receiving onabotulinumtoxinA had a decrease in their total monthly headache days (MHDs) and monthly migraine days (MMD). At baseline, while on onabotulinumtoxinA, mean MHDs were 22.5 ± 8.7 and mean MMDs were 15.8 ± 8.3, and 65 patients (83.3%) failed at least three preventative therapies. Our results demonstrated a significant reduction in MHDs and MMDs at 30- (-6.8 MHDs; p < 0.001, -7.0 MMDs; p < 0.001), 60- (-7.2 MHDs; p < 0.001, -6.7 MMDs; p < 0.001), and 90 days (-8.1 MHDs; p < 0.001, -7.4 MMDs; p < 0.001). Thus, the results of this study suggest favorable outcomes with the addition of erenumab to patients who were still suffering while receiving onabotulinumtoxinA therapy. Additional investigation is needed to determine if erenumab in combination with onabotulinumtoxinA has an enhanced effect on the modulation of CGRP release from peripheral unmyelinated C fibers while also blocking CGRP receptors in the myelinated A-delta fibers.


Assuntos
Anticorpos Monoclonais Humanizados/uso terapêutico , Toxinas Botulínicas Tipo A , Enxaqueca sem Aura , Toxinas Botulínicas Tipo A/uso terapêutico , Humanos , Enxaqueca sem Aura/tratamento farmacológico , Estudos Retrospectivos
4.
Pain Pract ; 18(5): 562-567, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-28941145

RESUMO

OBJECTIVE: The goal of this study was to determine the frequency and clinical indications associated with implantation of single vs. dual percutaneous lead spinal cord stimulator (SCS) systems and to look further into how these leads are utilized for treatment. MATERIALS AND METHODS: A retrospective cohort analysis of all patients undergoing SCS implantation between January 2001 and December 2013 with a minimum of 2 years of clinical follow-up was performed. Number of trial leads and implanted leads was recorded. For patients with dual-lead systems, it was noted if and when the second lead was used, along with the clinical indication for lead activation. RESULTS: In the 259-patient cohort, 15.8% (n = 41) patients underwent placement of a single-lead system, 83.0% (n = 215) underwent placement of a dual-lead system, and 1.2% (n = 3) underwent placement of 3-lead systems. Placement of dual-lead systems was similar among all indication groups. Of those patients with a dual-lead system in place, 88.1% utilized both leads and average time to programming of the second lead was 2.3 months. The most common reason to activate the second lead was inadequate stimulation coverage. Five of the 41 patients with single-lead systems underwent an additional surgery to implant a second lead due to inadequate stimulation with 1 lead. CONCLUSIONS: To our knowledge this is the first descriptive analysis of the frequency of single- and dual-lead SCS systems. This report indicates that dual-lead systems are most often placed and both leads are required for optimal patient therapy.


Assuntos
Eletrodos Implantados , Manejo da Dor/instrumentação , Estimulação da Medula Espinal/instrumentação , Adulto , Estudos de Coortes , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos
5.
Biomol Detect Quantif ; 8: 15-28, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27335807

RESUMO

Measurement of RNA can be used to study and monitor a range of infectious and non-communicable diseases, with profiling of multiple gene expression mRNA transcripts being increasingly applied to cancer stratification and prognosis. An international comparison study (Consultative Committee for Amount of Substance (CCQM)-P103.1) was performed in order to evaluate the comparability of measurements of RNA copy number ratio for multiple gene targets between two samples. Six exogenous synthetic targets comprising of External RNA Control Consortium (ERCC) standards were measured alongside transcripts for three endogenous gene targets present in the background of human cell line RNA. The study was carried out under the auspices of the Nucleic Acids (formerly Bioanalysis) Working Group of the CCQM. It was coordinated by LGC (United Kingdom) with the support of National Institute of Standards and Technology (USA) and results were submitted from thirteen National Metrology Institutes and Designated Institutes. The majority of laboratories performed RNA measurements using RT-qPCR, with datasets also being submitted by two laboratories based on reverse transcription digital polymerase chain reaction and one laboratory using a next-generation sequencing method. In RT-qPCR analysis, the RNA copy number ratios between the two samples were quantified using either a standard curve or a relative quantification approach. In general, good agreement was observed between the reported results of ERCC RNA copy number ratio measurements. Measurements of the RNA copy number ratios for endogenous genes between the two samples were also consistent between the majority of laboratories. Some differences in the reported values and confidence intervals ('measurement uncertainties') were noted which may be attributable to choice of measurement method or quantification approach. This highlights the need for standardised practices for the calculation of fold change ratios and uncertainties in the area of gene expression profiling.

6.
Pediatr Transplant ; 20(3): 372-7, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-26867508

RESUMO

To date, no study has analyzed the use of deep PS for pediatric renal biopsies by a dedicated sedation team in an outpatient setting. Retrospective analysis of renal biopsies performed at CHOA from 2009 to 2013. Patient demographics, procedure success, and sedation-related events were analyzed. Logistic regression techniques were applied to identify characteristics associated with procedure safety and success. A total of 174 biopsies from 136 patients, aged 2-21 yr, were reviewed. Of the 174 biopsies, 63 of 174 (36%) were from native, and 111 of 174 (64%) were from transplanted kidneys, respectively. No deaths, allograft losses, or unanticipated hospital admissions occurred. The most commonly utilized interventions during sedation were blow-by oxygen (29.9%) and CPAP (12.1%). Children receiving the combination of F + P had significantly higher biopsy success rates vs. other drug combinations (96.1% vs. 79%; p = 0.014). There was no difference in complication rates regardless of drug combination or biopsy type (transplanted vs. native). The combination of F + P yields a high procedural success rate for outpatient native and transplanted kidney biopsies. We identified a number of sedation-related events that can be easily managed by a well-trained sedationist team.


Assuntos
Anestesia/métodos , Transplante de Rim/métodos , Adolescente , Anestésicos/administração & dosagem , Biópsia , Criança , Pré-Escolar , Pressão Positiva Contínua nas Vias Aéreas , Feminino , Fentanila/administração & dosagem , Humanos , Rim/cirurgia , Masculino , Monitorização Fisiológica/métodos , Pacientes Ambulatoriais , Oxigênio , Admissão do Paciente , Alta do Paciente , Pediatria/métodos , Propofol/administração & dosagem , Análise de Regressão , Estudos Retrospectivos , Adulto Jovem
7.
Pain Pract ; 16(7): 899-904, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-26310826

RESUMO

INTRODUCTION: Spinal cord stimulators (SCS) are used to treat various chronic pain states. Establishing patient outcomes in terms of pain control, opioid medication use, and overall satisfaction is vital in maintaining SCS's role in clinical practice. METHODS: All patients who underwent SCS implantation between January 2001 and December 2011 at a tertiary academic pain medicine center were included if he or she underwent permanent cervical or thoracolumbar dorsal column SCS implantation and age was 18 or greater. For the 199 patients who met inclusion criteria, data were collected retrospectively. Preimplant information included indication for implantation, Numeric Rating Scale (NRS) score, and dose in oral morphine equivalents (OME). Postimplant NRS score was recorded at 6 months and 1 year. OME requirement and patient satisfaction were determined at 1 year postimplantation. RESULTS: This data set showed an overall decrease in OME requirements and NRS scores at both 6 months and 1 year. These differences were statistically significant (P < 0.01) compared to preimplantation values. Additionally, 84.27% of patients were satisfied with their implants at 1 year. Patient outcomes were analyzed further in respect to implant indication; groups included failed back surgery syndrome (FBSS), complex regional pain syndrome (CRPS), angina, and other. For all groups, there were statistically significant (P < 0.01) decreases in NRS scores at 6 months and 1 year. In the FBSS and CRPS groups, statistically significant (P < 0.02) decreases in OME usage existed. CONCLUSION: Retrospective review of patients with spinal cord stimulators revealed OME reduction at 1 year for those patients in the FBSS and CRPS groups; patient satisfaction at 1 year and NRS score reduction at 6 months and 1 year were statistically significant for all groups.


Assuntos
Dor Crônica/terapia , Satisfação do Paciente , Estimulação da Medula Espinal/métodos , Adulto , Síndromes da Dor Regional Complexa/terapia , Síndrome Pós-Laminectomia/terapia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Manejo da Dor/métodos , Medição da Dor , Estudos Retrospectivos
8.
Neuromodulation ; 18(4): 285-8; discussion 288, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25345833

RESUMO

INTRODUCTION: Spinal cord stimulator (SCS) systems are implanted to treat pain conditions such as neuropathic, radicular, and ischemic pain syndromes. Prior to July 2013, SCS systems were not magnetic resonance imaging (MRI) compatible due to the risk of thermal injury at the site of the leads and generator. Although there are some case reports of patients undergoing MRI studies with SCS systems in place, these stimulators are frequently explanted when clinical care has necessitated an MRI. The purpose of this case series is to discuss the role of SCS explantation in order to acquire an MRI. METHODS: This study was performed at a tertiary academic pain medicine clinic. After exempt status was obtained via the institutional review board, patients were identified via the use of Common Procedural Terminology codes for implantable devices. A chart review was performed to identify all patients >18 years of age who had a lumbar or thoracic dorsal column SCS implanted during January 2001-December 2011. The charts were then followed to identify any patients who underwent a surgery for explantation of the device. Data collection included the total number of patients undergoing permanent SCS implantation, the total number of explantation of these devices, patient demographic factors, indication for SCS implantation, incidence of revisions and the indication, duration between implantation and explant of the device, and indication for explantation. RESULTS: During the time between 2001 and 2011, 199 patients were identified who underwent a thoracic or lumbar SCS implant after a successful trial. Among 199 implants, 33 devices were explanted, and of these, four were explanted due to the primary need for an MRI scan.


Assuntos
Dor Crônica/terapia , Imageamento por Ressonância Magnética , Estimulação da Medula Espinal/métodos , Medula Espinal/fisiologia , Adulto , Idoso , Eletrodos Implantados , Feminino , Humanos , Estudos Longitudinais , Vértebras Lombares , Masculino , Pessoa de Meia-Idade , Clínicas de Dor , Adulto Jovem
9.
PLoS One ; 8(9): e75296, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24073259

RESUMO

Gene expression measurements detailing mRNA quantities are widely employed in molecular biology and are increasingly important in diagnostic fields. Reverse transcription (RT), necessary for generating complementary DNA, can be both inefficient and imprecise, but remains a quintessential RNA analysis tool using qPCR. This study developed a Transcriptomic Calibration Material and assessed the RT reaction using digital (d)PCR for RNA measurement. While many studies characterise dPCR capabilities for DNA quantification, less work has been performed investigating similar parameters using RT-dPCR for RNA analysis. RT-dPCR measurement using three, one-step RT-qPCR kits was evaluated using single and multiplex formats when measuring endogenous and synthetic RNAs. The best performing kit was compared to UV quantification and sensitivity and technical reproducibility investigated. Our results demonstrate assay and kit dependent RT-dPCR measurements differed significantly compared to UV quantification. Different values were reported by different kits for each target, despite evaluation of identical samples using the same instrument. RT-dPCR did not display the strong inter-assay agreement previously described when analysing DNA. This study demonstrates that, as with DNA measurement, RT-dPCR is capable of accurate quantification of low copy RNA targets, but the results are both kit and target dependent supporting the need for calibration controls.


Assuntos
Proteínas de Ligação a DNA/genética , Endonucleases/genética , Dosagem de Genes , RNA Neoplásico/genética , Reação em Cadeia da Polimerase em Tempo Real/métodos , Antígenos de Neoplasias/genética , Neoplasias Ósseas/genética , Carcinoma Hepatocelular/genética , Glioma/genética , Humanos , Neoplasias Hepáticas/genética , Metaloproteinase 1 da Matriz/genética , Osteossarcoma/genética , RNA Neoplásico/análise , Espectrofotometria Ultravioleta , Células Tumorais Cultivadas
10.
Blood ; 119(10): 2293-301, 2012 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-22234695

RESUMO

Leukemia cells from patients with chronic lymphocytic leukemia (CLL) express a highly restricted immunoglobulin heavy variable chain (IGHV) repertoire, suggesting that a limited set of antigens reacts with leukemic cells. Here, we evaluated the reactivity of a panel of different CLL recombinant antibodies (rAbs) encoded by the most commonly expressed IGHV genes with a panel of selected viral and bacterial pathogens. Six different CLL rAbs encoded by IGHV1-69 or IGHV3-21, but not a CLL rAb encoded by IGHV4-39 genes, reacted with a single protein of human cytomegalovirus (CMV). The CMV protein was identified as the large structural phosphoprotein pUL32. In contrast, none of the CLL rAbs bound to any other structure of CMV, adenovirus serotype 2, Salmonella enterica serovar Typhimurium, or of cells used for propagation of these microorganisms. Monoclonal antibodies or humanized rAbs of irrelevant specificity to pUL32 did not react with any of the proteins present in the different lysates. Still, rAbs encoded by a germ line IGHV1-69 51p1 allele from CMV-seropositive and -negative adults also reacted with pUL32. The observed reactivity of multiple different CLL rAbs and natural antibodies from CMV-seronegative adults with pUL32 is consistent with the properties of a superantigen.


Assuntos
Anticorpos Monoclonais/imunologia , Linfócitos B/imunologia , Citomegalovirus/imunologia , Cadeias Pesadas de Imunoglobulinas/imunologia , Fosfoproteínas/imunologia , Superantígenos/imunologia , Adulto , Anticorpos Monoclonais/genética , Especificidade de Anticorpos/imunologia , Linfócitos B/metabolismo , Western Blotting , Células Cultivadas , Células HEK293 , Humanos , Cadeias Pesadas de Imunoglobulinas/genética , Leucemia Linfocítica Crônica de Células B/genética , Leucemia Linfocítica Crônica de Células B/imunologia , Leucemia Linfocítica Crônica de Células B/metabolismo , Ligação Proteica/imunologia , Proteínas Recombinantes/imunologia , Salmonella typhimurium/imunologia , Proteínas Virais/imunologia
12.
Anal Chem ; 83(17): 6474-84, 2011 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-21446772

RESUMO

The emerging technique of microfluidic digital PCR (dPCR) offers a unique approach to real-time quantitative PCR for measuring nucleic acids that may be particularly suited for low-level detection. In this study, we evaluated the quantitative capabilities of dPCR when measuring small amounts (<200 copies) of DNA and investigated parameters influencing technical performance. We used various DNA templates, matrixes, and assays to evaluate the precision, sensitivity and reproducibility of dPCR, and demonstrate that this technique can be highly reproducible when performed at different times and when different primer sets are targeting the same molecule. dPCR exhibited good analytical sensitivity and was reproducible outside the range recommended by the instrument manufacturer; detecting 16 estimated targets with high precision. The inclusion of carrier had no effect on this estimated quantity, but did improve measurement precision. We report disagreement when using dPCR to measure different template types and when comparing the estimated quantities by dPCR and UV spectrophotometry. Finally, we also demonstrate that preamplification can impose a significant measurement bias. These findings provide an independent assessment of low copy molecular measurement using dPCR and underline important factors for consideration in dPCR experimental design.


Assuntos
DNA/análise , Técnicas Analíticas Microfluídicas/normas , Reação em Cadeia da Polimerase em Tempo Real/normas , Álcool Desidrogenase/genética , Álcool Desidrogenase/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Proteínas de Fusão bcr-abl/genética , Proteínas de Fusão bcr-abl/metabolismo , Técnicas Analíticas Microfluídicas/instrumentação , Técnicas Analíticas Microfluídicas/métodos , Espectrofotometria Ultravioleta
13.
Gen Hosp Psychiatry ; 31(3): 240-53, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19410103

RESUMO

OBJECTIVE: Pain and depression are two of the most prevalent and treatable cancer-related symptoms, each present in at least 20-30% of oncology patients. Both symptoms are frequently either unrecognized or undertreated, however. This article describes a telecare management intervention delivered by a nurse-psychiatrist team that is designed to improve recognition and treatment of pain and depression. The enrolled sample is also described. METHODS: The Indiana Cancer Pain and Depression study is a National Cancer Institute-sponsored randomized clinical trial. Four hundred five patients with cancer-related pain and/or clinically significant depression from 16 urban or rural oncology practices throughout Indiana have been enrolled and randomized to either the intervention group or to a usual-care control group. Intervention patients receive centralized telecare management coupled with automated home-based symptom monitoring. Outcomes will be assessed at 1, 3, 6 and 12 months by research assistants blinded to treatment arms. RESULTS: Of 4465 patients screened, 2185 (49%) endorsed symptoms of pain or depression. Of screen-positive patients, about one-third were ineligible (most commonly due to pain or depression not meeting severity thresholds or to pain that is not related to cancer). Of the 405 patients enrolled, 32% have depression only, 24% have pain only and 44% have both depression and pain. At baseline, participants reported an average of 16.8 days out of the past 4 weeks during which they were confined to bed or had to reduce their usual activities by > or =50% due to pain or depression. Also, 176 (44%) reported being unable to work due to health reasons. CONCLUSIONS: When completed, the Indiana Cancer Pain and Depression trial will test whether centralized telecare management coupled with automated home-based symptom monitoring improves outcomes in cancer patients with depression and/or pain. Findings will be important for both oncologists and mental health clinicians confronted with oncology patients' depression or pain.


Assuntos
Analgésicos/uso terapêutico , Transtorno Depressivo Maior/epidemiologia , Transtorno Depressivo Maior/terapia , Neoplasias/epidemiologia , Neoplasias/psicologia , Manejo da Dor , Dor/epidemiologia , Telemedicina/métodos , Antidepressivos/uso terapêutico , Comorbidade , Transtorno Depressivo Maior/diagnóstico , Tratamento Farmacológico/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Dor/diagnóstico , Índice de Gravidade de Doença , Inquéritos e Questionários
14.
J Virol ; 80(20): 9951-61, 2006 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-17005673

RESUMO

Human cytomegalovirus (HCMV) infection results in dysregulation of several cell cycle genes, including inhibition of cyclin A transcription. In this work, we examine the effect of the HCMV infection on expression of the high-mobility group A2 (HMGA2) gene, which encodes an architectural transcription factor that is involved in cyclin A promoter activation. We find that expression of HMGA2 RNA is repressed in infected cells. To determine whether repression of HMGA2 is directly related to the inhibition of cyclin A expression and impacts on the progression of the infection, we constructed an HCMV recombinant that expressed HMGA2. In cells infected with the recombinant virus, cyclin A mRNA and protein are induced, and there is a significant delay in viral early gene expression and DNA replication. To determine the mechanism of HMGA2 repression, we used recombinant viruses that expressed either no IE1 72-kDa protein (CR208) or greatly reduced levels of IE2 86-kDa (IE2 86) protein (IE2 86DeltaSX-EGFP). At a high multiplicity of infection, the IE1 deletion mutant is comparable to the wild type with respect to inhibition of HMGA2. In contrast, the IE2 86DeltaSX-EGFP mutant does not significantly repress HMGA2 expression, suggesting that IE2 86 is involved in the regulation of this gene. Cyclin A expression is also induced in cells infected with this mutant virus. Since HMGA2 is important for cell proliferation and differentiation, particularly during embryogenesis, it is possible that the repression of HMGA2 expression during fetal development could contribute to the specific birth defects in HCMV-infected neonates.


Assuntos
Ciclina A/genética , Citomegalovirus/fisiologia , Regulação da Expressão Gênica , Proteína HMGA2/genética , Proteínas Imediatamente Precoces/fisiologia , Transativadores/fisiologia , Transcrição Gênica , Replicação Viral , Células Cultivadas , Ciclina A/biossíntese , Citomegalovirus/genética , Proteína HMGA2/biossíntese , Humanos , Proteínas Imediatamente Precoces/genética , RNA/análise , RNA/genética , Proteínas Recombinantes/biossíntese , Recombinação Genética , Transativadores/genética , Proteínas Virais/genética , Proteínas Virais/fisiologia
15.
J Biol Chem ; 279(31): 32796-803, 2004 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-15175331

RESUMO

UDP-galactose 4'-epimerase (GALE) interconverts UDP-galactose and UDP-glucose in the final step of the Leloir pathway. Unlike the Escherichia coli enzyme, human GALE (hGALE) also efficiently interconverts a larger pair of substrates: UDP-N-acetylgalactosamine and UDP-N-acetylglucosamine. The basis of this differential substrate specificity has remained obscure. Recently, however, x-ray crystallographic data have both predicted essential active site residues and suggested that differential active site cleft volume may be a key factor in determining GALE substrate selectivity. We report here a direct test of this hypothesis. In brief, we have created four substituted alleles: S132A, Y157F, S132A/Y157F, and C307Y-hGALE. While the first three substitutions were predicted to disrupt catalytic activity, the fourth was predicted to reduce active site cleft volume, thereby limiting entry or rotation of the larger but not the smaller substrate. All four alleles were expressed in a null-background strain of Saccharomyces cerevisiae and characterized in terms of activity with regard to both UDP-galactose and UDP-N-acetylgalactosamine. The S132A/Y157F and C307Y-hGALE proteins were also overexpressed in Pichia pastoris and purified for analysis. In all forms tested, the Y157F, S132A, and Y157F/S132A-hGALE proteins each demonstrated a complete loss of activity with respect to both substrates. In contrast, the C307Y-hGALE demonstrated normal activity with respect to UDP-galactose but complete loss of activity with respect to UDP-N-acetylgalactosamine. Together, these results serve to validate the wild-type hGALE crystal structure and fully support the hypothesis that residue 307 acts as a gatekeeper mediating substrate access to the hGALE active site.


Assuntos
UDPglucose 4-Epimerase/química , Alelos , Sítios de Ligação , Catálise , Cisteína/química , Escherichia coli/metabolismo , Galactose/química , Humanos , Modelos Biológicos , Modelos Moleculares , Mutação , Pichia/metabolismo , Plasmídeos/metabolismo , Saccharomyces cerevisiae/metabolismo , Serina/química , Especificidade por Substrato , Tirosina/química , Uridina Difosfato N-Acetilgalactosamina/química , Uridina Difosfato N-Acetilglicosamina/química
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