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BACKGROUND: Nursing home residents are at high risk for infection, hospitalization, and colonization with multidrug-resistant organisms. METHODS: We performed a cluster-randomized trial of universal decolonization as compared with routine-care bathing in nursing homes. The trial included an 18-month baseline period and an 18-month intervention period. Decolonization entailed the use of chlorhexidine for all routine bathing and showering and administration of nasal povidone-iodine twice daily for the first 5 days after admission and then twice daily for 5 days every other week. The primary outcome was transfer to a hospital due to infection. The secondary outcome was transfer to a hospital for any reason. An intention-to-treat (as-assigned) difference-in-differences analysis was performed for each outcome with the use of generalized linear mixed models to compare the intervention period with the baseline period across trial groups. RESULTS: Data were obtained from 28 nursing homes with a total of 28,956 residents. Among the transfers to a hospital in the routine-care group, 62.2% (the mean across facilities) were due to infection during the baseline period and 62.6% were due to infection during the intervention period (risk ratio, 1.00; 95% confidence interval [CI], 0.96 to 1.04). The corresponding values in the decolonization group were 62.9% and 52.2% (risk ratio, 0.83; 95% CI, 0.79 to 0.88), for a difference in risk ratio, as compared with routine care, of 16.6% (95% CI, 11.0 to 21.8; P<0.001). Among the discharges from the nursing home in the routine-care group, transfer to a hospital for any reason accounted for 36.6% during the baseline period and for 39.2% during the intervention period (risk ratio, 1.08; 95% CI, 1.04 to 1.12). The corresponding values in the decolonization group were 35.5% and 32.4% (risk ratio, 0.92; 95% CI, 0.88 to 0.96), for a difference in risk ratio, as compared with routine care, of 14.6% (95% CI, 9.7 to 19.2). The number needed to treat was 9.7 to prevent one infection-related hospitalization and 8.9 to prevent one hospitalization for any reason. CONCLUSIONS: In nursing homes, universal decolonization with chlorhexidine and nasal iodophor led to a significantly lower risk of transfer to a hospital due to infection than routine care. (Funded by the Agency for Healthcare Research and Quality; Protect ClinicalTrials.gov number, NCT03118232.).
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Antiinfecciosos Locales , Infecciones Asintomáticas , Clorhexidina , Infección Hospitalaria , Casas de Salud , Povidona Yodada , Humanos , Administración Cutánea , Administración Intranasal , Antiinfecciosos Locales/administración & dosificación , Antiinfecciosos Locales/uso terapéutico , Baños , Clorhexidina/administración & dosificación , Clorhexidina/uso terapéutico , Infección Hospitalaria/epidemiología , Infección Hospitalaria/prevención & control , Infección Hospitalaria/terapia , Hospitalización/estadística & datos numéricos , Casas de Salud/estadística & datos numéricos , Transferencia de Pacientes/estadística & datos numéricos , Povidona Yodada/administración & dosificación , Povidona Yodada/uso terapéutico , Cuidados de la Piel/métodos , Infecciones Asintomáticas/terapiaRESUMEN
Importance: Infections due to multidrug-resistant organisms (MDROs) are associated with increased morbidity, mortality, length of hospitalization, and health care costs. Regional interventions may be advantageous in mitigating MDROs and associated infections. Objective: To evaluate whether implementation of a decolonization collaborative is associated with reduced regional MDRO prevalence, incident clinical cultures, infection-related hospitalizations, costs, and deaths. Design, Setting, and Participants: This quality improvement study was conducted from July 1, 2017, to July 31, 2019, across 35 health care facilities in Orange County, California. Exposures: Chlorhexidine bathing and nasal iodophor antisepsis for residents in long-term care and hospitalized patients in contact precautions (CP). Main Outcomes and Measures: Baseline and end of intervention MDRO point prevalence among participating facilities; incident MDRO (nonscreening) clinical cultures among participating and nonparticipating facilities; and infection-related hospitalizations and associated costs and deaths among residents in participating and nonparticipating nursing homes (NHs). Results: Thirty-five facilities (16 hospitals, 16 NHs, 3 long-term acute care hospitals [LTACHs]) adopted the intervention. Comparing decolonization with baseline periods among participating facilities, the mean (SD) MDRO prevalence decreased from 63.9% (12.2%) to 49.9% (11.3%) among NHs, from 80.0% (7.2%) to 53.3% (13.3%) among LTACHs (odds ratio [OR] for NHs and LTACHs, 0.48; 95% CI, 0.40-0.57), and from 64.1% (8.5%) to 55.4% (13.8%) (OR, 0.75; 95% CI, 0.60-0.93) among hospitalized patients in CP. When comparing decolonization with baseline among NHs, the mean (SD) monthly incident MDRO clinical cultures changed from 2.7 (1.9) to 1.7 (1.1) among participating NHs, from 1.7 (1.4) to 1.5 (1.1) among nonparticipating NHs (group × period interaction reduction, 30.4%; 95% CI, 16.4%-42.1%), from 25.5 (18.6) to 25.0 (15.9) among participating hospitals, from 12.5 (10.1) to 14.3 (10.2) among nonparticipating hospitals (group × period interaction reduction, 12.9%; 95% CI, 3.3%-21.5%), and from 14.8 (8.6) to 8.2 (6.1) among LTACHs (all facilities participating; 22.5% reduction; 95% CI, 4.4%-37.1%). For NHs, the rate of infection-related hospitalizations per 1000 resident-days changed from 2.31 during baseline to 1.94 during intervention among participating NHs, and from 1.90 to 2.03 among nonparticipating NHs (group × period interaction reduction, 26.7%; 95% CI, 19.0%-34.5%). Associated hospitalization costs per 1000 resident-days changed from $64â¯651 to $55â¯149 among participating NHs and from $55â¯151 to $59â¯327 among nonparticipating NHs (group × period interaction reduction, 26.8%; 95% CI, 26.7%-26.9%). Associated hospitalization deaths per 1000 resident-days changed from 0.29 to 0.25 among participating NHs and from 0.23 to 0.24 among nonparticipating NHs (group × period interaction reduction, 23.7%; 95% CI, 4.5%-43.0%). Conclusions and Relevance: A regional collaborative involving universal decolonization in long-term care facilities and targeted decolonization among hospital patients in CP was associated with lower MDRO carriage, infections, hospitalizations, costs, and deaths.
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Antiinfecciosos Locales , Infecciones Bacterianas , Infección Hospitalaria , Farmacorresistencia Bacteriana Múltiple , Instituciones de Salud , Control de Infecciones , Anciano , Humanos , Administración Intranasal , Antiinfecciosos Locales/administración & dosificación , Antiinfecciosos Locales/uso terapéutico , Infecciones Bacterianas/economía , Infecciones Bacterianas/microbiología , Infecciones Bacterianas/mortalidad , Infecciones Bacterianas/prevención & control , Baños/métodos , California/epidemiología , Clorhexidina/administración & dosificación , Clorhexidina/uso terapéutico , Infección Hospitalaria/economía , Infección Hospitalaria/microbiología , Infección Hospitalaria/mortalidad , Infección Hospitalaria/prevención & control , Instituciones de Salud/economía , Instituciones de Salud/normas , Instituciones de Salud/estadística & datos numéricos , Hospitalización/economía , Hospitalización/estadística & datos numéricos , Hospitales/normas , Hospitales/estadística & datos numéricos , Control de Infecciones/métodos , Yodóforos/administración & dosificación , Yodóforos/uso terapéutico , Casas de Salud/economía , Casas de Salud/normas , Casas de Salud/estadística & datos numéricos , Transferencia de Pacientes , Mejoramiento de la Calidad/economía , Mejoramiento de la Calidad/estadística & datos numéricos , Cuidados de la Piel/métodos , Precauciones UniversalesRESUMEN
INTRODUCTION: Amid recent approvals, early Alzheimer's disease (AD) remains an active area of treatment development. METHODS: We performed a conjoint experiment to compare preferences among 26 patients with mild cognitive impairment for four trial features including designs incorporating active aducanumab-control (vs. placebo), returning tau positron emission tomography (PET) results (vs. no disclosure), remote study partner participation (vs. in person), and increased risk of brain swelling (vs. lower risk). We used a generalized estimating equation to model the utility of factor levels. RESULTS: Returning tau PET results had the highest utility (est: 0.47; 95% confidence interval [CI]: 0.13, 0.81; P = 0.007); remote study partner participation showed a similar trend (est: 0.29; 95% CI: -0.05, 0.63; P = 0.097). Trials with active-controlled design (est: 0.01; 95% CI: -0.33, 0.35; P = 0.956) did not demonstrate utility and higher risk of brain swelling had negative utility (est: -0.64; 95% CI: -0.99, -0.30; P < 0.001). DISCUSSION: Returning additional biomarker results may increase willingness to enroll in early AD trials. HIGHLIGHTS: We compared mild cognitive impairment participant preferences for four trial design features. Returning tau positron emission tomography results had the highest utility. Remote study partner participation showed a positive, albeit non-significant, trend. No utility was observed for an active aducanumab-control design.
RESUMEN
BACKGROUND: The CLEAR Trial demonstrated that a multisite body decolonization regimen reduced post-discharge infection and hospitalization in methicillin-resistant Staphylococcus aureus (MRSA) carriers. Here, we describe decolonization efficacy. METHODS: We performed a large, multicenter, randomized clinical trial of MRSA decolonization among adult patients after hospital discharge with MRSA infection or colonization. Participants were randomized 1:1 to either MRSA prevention education or education plus decolonization with topical chlorhexidine, oral chlorhexidine, and nasal mupirocin. Participants were swabbed in the nares, throat, axilla/groin, and wound (if applicable) at baseline and 1, 3, 6, and 9 months after randomization. The primary outcomes of this study are follow-up colonization differences between groups. RESULTS: Among 2121 participants, 1058 were randomized to decolonization. By 1 month, MRSA colonization was lower in the decolonization group compared with the education-only group (odds ration [OR] = 0.44; 95% confidence interval [CI], .36-.54; P ≤ .001). A similar magnitude of reduction was seen in the nares (OR = 0.34; 95% CI, .27-.42; P < .001), throat (OR = 0.55; 95% CI, .42-.73; P < .001), and axilla/groin (OR = 0.57; 95% CI, .43-.75; P < .001). These differences persisted through month 9 except at the wound site, which had a relatively small sample size. Higher regimen adherence was associated with lower MRSA colonization (P ≤ .01). CONCLUSIONS: In a randomized, clinical trial, a repeated post-discharge decolonization regimen for MRSA carriers reduced MRSA colonization overall and at multiple body sites. Higher treatment adherence was associated with greater reductions in MRSA colonization.
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Staphylococcus aureus Resistente a Meticilina , Infecciones Estafilocócicas , Adulto , Humanos , Mupirocina/uso terapéutico , Clorhexidina/uso terapéutico , Antibacterianos/uso terapéutico , Antibacterianos/farmacología , Alta del Paciente , Cuidados Posteriores , Infecciones Estafilocócicas/tratamiento farmacológico , Infecciones Estafilocócicas/prevención & control , Portador Sano/tratamiento farmacológico , Portador Sano/prevención & control , Farmacorresistencia Microbiana , HospitalesRESUMEN
INTRODUCTION: Effective strategies to recruit older adults with mild cognitive impairment (MCI) into nonpharmacological intervention trials are lacking. METHODS: Recruitment for EXERT, a multisite randomized controlled 18-month trial examining the effects of aerobic exercise on cognitive trajectory in adults with amnestic MCI, involved a diverse portfolio of strategies to enroll 296 participants. RESULTS: Recruitment occurred September 2016 through March 2020 and was initially slow. After mass mailings of 490,323 age- and geo-targeted infographic postcards and brochures, recruitment rates increased substantially, peaking at 16 randomizations/month in early 2020. Mass mailings accounted for 52% of randomized participants, whereas 25% were recruited from memory clinic rosters, electronic health records, and national and local registries. Other sources included news broadcasts, public service announcements (PSA), local advertising, and community presentations. DISCUSSION: Age- and geo-targeted mass mailing of infographic materials was the most effective approach in recruiting older adults with amnestic MCI into an 18-month exercise trial.
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Amnesia/terapia , Disfunción Cognitiva/terapia , Ejercicio Físico , Folletos , Selección de Paciente , Anciano , Cognición , Femenino , Humanos , Masculino , Servicios PostalesRESUMEN
BACKGROUND: Multidrug-resistant organisms (MDROs) spread between hospitals, nursing homes (NHs), and long-term acute care facilities (LTACs) via patient transfers. The Shared Healthcare Intervention to Eliminate Life-threatening Dissemination of MDROs in Orange County is a regional public health collaborative involving decolonization at 38 healthcare facilities selected based on their high degree of patient sharing. We report baseline MDRO prevalence in 21 NHs/LTACs. METHODS: A random sample of 50 adults for 21 NHs/LTACs (18 NHs, 3 LTACs) were screened for methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus spp. (VRE), extended-spectrum ß-lactamase-producing organisms (ESBL), and carbapenem-resistant Enterobacteriaceae (CRE) using nares, skin (axilla/groin), and peri-rectal swabs. Facility and resident characteristics associated with MDRO carriage were assessed using multivariable models clustering by person and facility. RESULTS: Prevalence of MDROs was 65% in NHs and 80% in LTACs. The most common MDROs in NHs were MRSA (42%) and ESBL (34%); in LTACs they were VRE (55%) and ESBL (38%). CRE prevalence was higher in facilities that manage ventilated LTAC patients and NH residents (8% vs <1%, P < .001). MDRO status was known for 18% of NH residents and 49% of LTAC patients. MDRO-colonized adults commonly harbored additional MDROs (54% MDRO+ NH residents and 62% MDRO+ LTACs patients). History of MRSA (odds ratio [OR] = 1.7; confidence interval [CI]: 1.2, 2.4; P = .004), VRE (OR = 2.1; CI: 1.2, 3.8; P = .01), ESBL (OR = 1.6; CI: 1.1, 2.3; P = .03), and diabetes (OR = 1.3; CI: 1.0, 1.7; P = .03) were associated with any MDRO carriage. CONCLUSIONS: The majority of NH residents and LTAC patients harbor MDROs. MDRO status is frequently unknown to the facility. The high MDRO prevalence highlights the need for prevention efforts in NHs/LTACs as part of regional efforts to control MDRO spread.
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Cuidados a Largo Plazo/estadística & datos numéricos , Casas de Salud/estadística & datos numéricos , California/epidemiología , Enterobacteriaceae Resistentes a los Carbapenémicos/patogenicidad , Clorhexidina/uso terapéutico , Farmacorresistencia Bacteriana Múltiple , Infecciones por Enterobacteriaceae/epidemiología , Humanos , Staphylococcus aureus Resistente a Meticilina/patogenicidad , Prevalencia , Salud Pública , Infecciones Estafilocócicas/epidemiología , Enterococos Resistentes a la Vancomicina/patogenicidadRESUMEN
OBJECTIVE: To compare patients with autopsy-confirmed Alzheimer disease (AD) and dementia with Lewy bodies (DLB) on the frequency of behaviors related to frontal system dysfunction and the association of these behaviors with dementia severity. METHODS: We performed a cross-sectional survey of a longitudinal cohort at a university research center for AD on a volunteer sample of 19 DLB and 38 AD participants with autopsy-confirmed diagnoses, similar in age (DLB: 77.3, AD: 77.5), education (DLB: 15.2, AD: 14.7), and Mini-Mental State Examination (MMSE) score (DLB: 20.6, AD: 20.5), with impairment ranging from mild deficits to moderate dementia. The Frontal Systems Behavior Scale (FrSBe)-Family Rating Form assessing patient apathy, disinhibition, and executive dysfunction by a knowledgeable informant was used. RESULTS: A two-way analysis of variance with the FrSBe total as the dependent variable revealed a significant MMSE by diagnosis interaction (F(1,53) = 9.34, p = 0.004). Mean FrSBe total for AD patients showed significant impairment across the range of dementia severity, whereas it was relatively preserved for DLB patients in the early stage of disease. The interaction term showed the same pattern for the executive dysfunction (F(1,53) = 7.62, p = 0.008), disinhibition (F(1,53) = 4.90, p = 0.031), and apathy (F(1,53) = 9.77, p = 0.003) subscales. CONCLUSION: Although frontal behavioral symptoms in AD patients were present regardless of stage of dementia, DLB patients showed significant frontal dysfunction only in later stages. Results suggest that frontal subcortical circuits associated with behaviors assessed by the FrSBe are affected early in AD but not until later stages in DLB. Assessing specific behaviors related to frontal systems, coupled with stage of cognitive decline, may aid in clinical differentiation of AD and DLB.
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Enfermedad de Alzheimer/fisiopatología , Enfermedad de Alzheimer/psicología , Lóbulo Frontal/fisiopatología , Enfermedad por Cuerpos de Lewy/fisiopatología , Enfermedad por Cuerpos de Lewy/psicología , Anciano , Apatía , Estudios Transversales , Función Ejecutiva , Femenino , Humanos , Inhibición Psicológica , Masculino , Pruebas Neuropsicológicas , Índice de Severidad de la Enfermedad , Evaluación de SíntomasRESUMEN
Standardized observation of bed baths and showers for 100 residents in 8 nursing homes revealed inadequate cleansing of body sites (88%-100% failure) and >90% process failure involving lather, firm massage, changing dirty wipes or cloths, and following clean-to-dirty sequence. Insufficient water warmth affected 86% of bathing opportunities. Bathing training and adequate resources are needed.
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Baños , Casas de Salud , Humanos , Instituciones de Cuidados Especializados de EnfermeríaRESUMEN
OBJECTIVE: Determine the prevalence of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus spp. (VRE), extended-spectrum beta-lactamase producing organisms (ESBLs), and carbapenem-resistant Enterobacteriaceae (CRE) among residents and in the environment of nursing homes (NHs). DESIGN: Point prevalence sampling of residents and environmental sampling of high-touch objects in resident rooms and common areas. SETTING: Twenty-eight NHs in Southern California from 2016 to 2017. PARTICIPANTS: NH participants in Project PROTECT, a cluster-randomized trial of enhanced bathing and decolonization vs routine care. METHODS: Fifty residents were randomly sampled per NH. Twenty objects were sampled, including 5 common room objects plus 5 objects in each of 3 rooms (ambulatory, total care, and dementia care residents). RESULTS: A total of 2797 swabs were obtained from 1400 residents in 28 NHs. Median prevalence of multidrug-resistant organism (MDRO) carriage per NH was 50% (range: 24%-70%). Median prevalence of specific MDROs were as follows: MRSA, 36% (range: 20%-54%); ESBL, 16% (range: 2%-34%); VRE, 5% (range: 0%-30%); and CRE, 0% (range: 0%-8%). A median of 45% of residents (range: 24%-67%) harbored an MDRO without a known MDRO history. Environmental MDRO contamination was found in 74% of resident rooms and 93% of common areas. CONCLUSIONS AND IMPLICATIONS: In more than half of the NHs, more than 50% of residents were colonized with MDROs of clinical and public health significance, most commonly MRSA and ESBL. Additionally, the vast majority of resident rooms and common areas were MDRO contaminated. The unknown submerged portion of the iceberg of MDRO carriers in NHs may warrant changes to infection prevention and control practices, particularly high-fidelity adoption of universal strategies such as hand hygiene, environmental cleaning, and decolonization.
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Infección Hospitalaria , Staphylococcus aureus Resistente a Meticilina , Enterococos Resistentes a la Vancomicina , Infección Hospitalaria/tratamiento farmacológico , Infección Hospitalaria/epidemiología , Infección Hospitalaria/prevención & control , Farmacorresistencia Bacteriana Múltiple , Humanos , Casas de Salud , PrevalenciaRESUMEN
The sequences of rat testis carbonyl reductase (rCR1) and rat ovary carbonyl reductase (rCR2) are 98% identical, differing only at amino acids 140, 141, 143, 235 and 238. Despite such strong sequence identity, we find that rCR1 and rCR2 have different catalytic constants for metabolism of menadione and 4-benzoyl-pyridine. Compared to rCR1, rCR2 has a 20-fold lower K(m) and 5-fold lower k(cat) towards menadione and a 7-fold lower K(m) and 7-fold lower k(cat) towards 4-benzoyl-pyridine. We constructed hybrids of rCR1 and rCR2 that were changed at either residues 140, 141 and 143 or residues 235 and 238. rCR1 with residues 140, 141 and 143 of rCR2 has similar catalytic efficiency for menadione and 4-benzoyl-pyridine as rCR1. rCR1 with Thr-235 and Glu-238 of rCR2 has the catalytic constants of rCR2, indicating that it is this part of rCR2 that contributes to its lower K(m) for menadione and 4-benzoyl-pyridine. Comparisons of three-dimensional models of rCR1 and rCR2 show how Thr-235 and Glu-238 stabilize rCR2 binding of NADPH and menadione.
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Oxidorreductasas de Alcohol/química , Ovario/enzimología , Testículo/enzimología , Oxidorreductasas de Alcohol/genética , Oxidorreductasas de Alcohol/metabolismo , Aminoácidos/química , Aminoácidos/genética , Aminoácidos/metabolismo , Animales , Catálisis , Femenino , Isoenzimas/química , Isoenzimas/genética , Isoenzimas/metabolismo , Masculino , Especificidad de Órganos/fisiología , Estructura Terciaria de Proteína , Piridinas/química , Piridinas/metabolismo , Ratas , Homología Estructural de Proteína , Vitamina K 3/química , Vitamina K 3/metabolismoRESUMEN
Nursing home residents are at risk for acquiring and transmitting MDROs. A serial point-prevalence study of 605 residents in 3 facilities using random sampling found MDRO colonization in 45% of residents: methicillin-resistant Staphylococcus aureus (MRSA, 26%); extended-spectrum ß-lactamase-producing Enterobacteriaceae (ESBL, 17%); vancomycin-resistant Enterococcus spp. (VRE, 16%); carbapenem-resistant Enterobacteriaceae (CRE, 1%). MDRO colonization was associated with history of MDRO, care needs, incontinence, and catheters. Infect Control Hosp Epidemiol 2016;1485-1488.
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Infección Hospitalaria/microbiología , Farmacorresistencia Bacteriana Múltiple , Infecciones por Enterobacteriaceae/epidemiología , Enterobacteriaceae/aislamiento & purificación , Staphylococcus aureus Resistente a Meticilina/aislamiento & purificación , Infecciones Estafilocócicas/epidemiología , California/epidemiología , Enterobacteriaceae Resistentes a los Carbapenémicos/aislamiento & purificación , Infección Hospitalaria/epidemiología , Humanos , Modelos Lineales , Casas de Salud , Prevalencia , Factores de Riesgo , Enterococos Resistentes a la Vancomicina/aislamiento & purificación , beta-Lactamasas/aislamiento & purificaciónRESUMEN
Organotins, important environmental pollutants widely used in agricultural and industrial applications, accumulate in the food chain and induce imposex in several marine species as well as neurotoxic and immunotoxic effects in higher animals. Reduced birth weight and thymus involution, observed upon exposure to organotins, can also be caused by excessive glucocorticoid levels. We now demonstrate that organotins efficiently inhibit 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2), converting active 11beta-hydroxyglucocorticoids into inactive 11-ketoglucocorticoids, but not 11beta-HSD1, which catalyzes the reverse reaction. Di- and tributyltin as well as di- and triphenyltin inhibited recombinant and endogenous 11beta-HSD2 in lysates and intact cells with IC50 values between 500 nM and 3 microM. Dithiothreitol protected 11beta-HSD2 from organotin-dependent inhibition, indicating that organotins act by binding to one or more cysteines. Mutational analysis and 3-D structural modeling revealed several important interactions of cysteines in 11beta-HSD2. Cys90, Cys228, and Cys264 were essential for enzymatic stability and catalytic activity, suggesting that disruption of such interactions by organotins leads to inhibition of 11beta-HSD2. Enhanced glucocorticoid concentrations due to disruption of 11beta-HSD2 function may contribute to the observed organotin-dependent toxicity in some glucocorticoid-sensitive tissues such as thymus and placenta.
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11-beta-Hidroxiesteroide Deshidrogenasa de Tipo 2/antagonistas & inhibidores , Glucocorticoides/metabolismo , Compuestos Orgánicos de Estaño/toxicidad , 11-beta-Hidroxiesteroide Deshidrogenasa de Tipo 1/metabolismo , 11-beta-Hidroxiesteroide Deshidrogenasa de Tipo 2/genética , 11-beta-Hidroxiesteroide Deshidrogenasa de Tipo 2/metabolismo , Línea Celular , Ditiotreitol/farmacología , Humanos , Mutagénesis Sitio-Dirigida , TransfecciónRESUMEN
The renal 11beta-hydroxysteroid dehydrogenase (11beta-HSD) type 2 catalyzes the NAD(+)-dependent oxidation of the C11-alcohol on cortisol and corticosterone to yield inactive 11-ketosteroids. The lack of purified active enzyme complicates structure-function analyses of 11beta-HSD2. Here, we constructed a 3D-structural model of 11beta-HSD2, based on known 3D-structures of other short-chain dehydrogenases/reductases (SDR), and functionally analyzed 11beta-HSD2 mutants predicted to be involved in cofactor binding. Our 3D-model explains the preference for NAD(+) over NADP(+) by the coulombic repulsion between the adenosine ribose 2'-phosphate on NADP(+) and the carboxylate on Glu(115) and to steric hindrance with the side chain on Glu(115). Indeed, replacement of Glu(115) with serine or threonine, lacking repulsive charge and unfavorable steric interactions, showed only 3-fold preference for NAD(+), compared to 40-fold for wild-type 11beta-HSD2. Mutation of both Asp(91) and Glu(115) to serine raised NADP(+)-dependent activity to that with NAD(+), but caused reduced enzymatic activity. The 3D-model predicted that this is due to a loss of stabilizing interactions of Asp(91) with Cys(90), Glu(115), Asn(117) and Gly(120). Thus, predictions using the 3D-model combined with analysis of mutants allowed the identification of residues critical for NAD(+)-dependent activity of 11beta-HSD2.
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11-beta-Hidroxiesteroide Deshidrogenasa de Tipo 2/metabolismo , Glutamatos/metabolismo , NADP/metabolismo , NAD/metabolismo , Secuencia de Aminoácidos , Ácido Aspártico/química , Ácido Aspártico/genética , Sitios de Unión , Dominio Catalítico , Simulación por Computador , Humanos , Datos de Secuencia Molecular , Mutagénesis Sitio-Dirigida , Fenilalanina/química , Fenilalanina/genética , Conformación Proteica , Homología de Secuencia de AminoácidoRESUMEN
Dexamethasone (Dex) is a potent and long-acting glucocorticoid in terms of anti-inflammatory activity without substantial sodium retaining effect. Here, we examine the ability of the 11beta-hydroxyglucocorticoids Dex and cortisol and their 11-keto forms 11-ketodexamethasone (11-ketoDex) and cortisone to bind to glucocorticoid receptors (GR) and mineralocorticoid receptors (MR) and to mediate nuclear translocation and transactivation of a reporter-gene. Unlike cortisone, the 11-ketosteroid 11-ketoDex acts as a potent GR agonist, comparable to Dex and cortisol. Transactivation of MR by Dex or 11-ketoDex was weak or undetectable, despite efficient binding and induction of nuclear translocation. 11beta-HSD2 protects MR and GR from inappropriate occupation by cortisol; it is, however, unable to prevent activation of GR by 11-ketoDex. The finding that 11-ketoDex is a specific GR agonist may explain the potent glucocorticoid effect of Dex in tissues expressing 11beta-HSD2 including kidney and colon and also in certain tumor cells.
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Dexametasona/farmacología , Cetosteroides/farmacología , Receptores de Glucocorticoides/agonistas , Transporte Activo de Núcleo Celular/efectos de los fármacos , Animales , Sitios de Unión , Línea Celular , Dexametasona/análogos & derivados , Humanos , Hidrocortisona/farmacología , Cinética , Unión Proteica , Receptores de Glucocorticoides/metabolismo , Receptores de Glucocorticoides/fisiología , Activación TranscripcionalRESUMEN
OBJECTIVE: To assess the changes in the multi-planar bending properties of intervertebral joints following cyclic bending along different directions. DESIGN: An in vitro biomechanical study using porcine lumbar motion segments. BACKGROUND: Repeated bending has been suggested as part of the etiology of gradual prolapse of the intervertebral disc, but the multi-planar changes in bending properties following cyclic loading have not been examined in detail. METHODS: Porcine lumbar motion segments were subject to 1500 cycles of bending along directions of 0 degrees (flexion), 30 degrees, 60 degrees, or 90 degrees (right lateral bending). The multi-planar bending moments and hysteresis energies were recorded before loading and after various cycle numbers. RESULTS: Repeated bending at 30 degrees and 60 degrees resulted in greater decreases in mean bending moment and hysteresis energy than bending at 0 degrees or 90 degrees. No significant differences were seen between loading groups for the change in bending moment along the anterior testing directions, but significant differences were observed in the posterior and lateral testing directions, with bending at 30 degrees causing a significantly greater decrease in bending moment in the postero-lateral directions. CONCLUSIONS: The change in mechanical properties of porcine intervertebral joints due to cyclic bending depend on the direction of loading and the direction in which the properties are measured. Loading at 30 degrees provokes the most marked changes in bending moment and hysteresis energy.
Asunto(s)
Fenómenos Biomecánicos , Disco Intervertebral/fisiología , Vértebras Lumbares/fisiología , Rango del Movimiento Articular/fisiología , Análisis de Varianza , Animales , Fuerza Compresiva , Técnicas de Cultivo , Probabilidad , Sensibilidad y Especificidad , Estrés Mecánico , Porcinos , Soporte de Peso/fisiologíaRESUMEN
Dithiocarbamates (DTCs), important therapeutic and industrial chemicals released in high quantities into the environment, exhibit complex chemical and biological activities. Here, we demonstrate an effect of DTCs on glucocorticoid action due to inhibition of 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) type 2, converting cortisol to cortisone in the kidney, but not 11 beta-HSD1, catalyzing the reverse reaction in liver and adipose tissue. Thus, DTCs may locally increase active glucocorticoid concentrations. Preincubation with the DTC thiram abolished 11 beta-HSD2 activity, suggesting irreversible enzyme inhibition. The sulfhydryl protecting reagent dithiothreitol blocked thiram-induced inhibition and NAD+ partially protected 11 beta-HSD2 activity, indicating that DTCs act at the cofactor-binding site. A 3D-model of 11 beta-HSD2 identified Cys90 in the NAD(+)-binding site as a likely target of DTCs, which was supported by a 99% reduced activity of mutant Cys90 to serine. The interference of DTCs with glucocorticoid-mediated responses suggests a cautious approach in the use of DTCs in therapeutic applications and in exposure to sources of DTCs such as cosmetics and agricultural products by pregnant women and others.
Asunto(s)
Inhibidores Enzimáticos/toxicidad , Hidroxiesteroide Deshidrogenasas/antagonistas & inhibidores , Tiocarbamatos/toxicidad , 11-beta-Hidroxiesteroide Deshidrogenasa de Tipo 2 , Sustitución de Aminoácidos , Dominio Catalítico/genética , Línea Celular , Cisteína/química , Contaminantes Ambientales/toxicidad , Inhibidores Enzimáticos/química , Humanos , Hidroxiesteroide Deshidrogenasas/química , Hidroxiesteroide Deshidrogenasas/genética , Modelos Moleculares , Estructura Molecular , Mutagénesis Sitio-Dirigida , NAD/farmacología , Proteínas Recombinantes/antagonistas & inhibidores , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Tiocarbamatos/química , Tiram/farmacología , Tiram/toxicidad , TransfecciónRESUMEN
Although endothelin-1-stimulated contractile force generation by stellate cells is believed to play an important role in hepatic pathophysiology, the molecular signals that mediate this process are incompletely understood. The aim of this study was to test the hypothesis that myosin mediates the contractile force generated by stellate cells in response to endothelin-1. Contractile force generation by primary and immortalized stellate cells was directly and quantitatively measured. Myosin phosphorylation and reorganization, and actin stress fiber formation were investigated in immortalized stellate cells. Endothelin-1 stimulated a rapid and robust generation of contractile force by primary and immortalized stellate cells with a similar dose dependence. Myosin phosphorylation, actin stress fiber assembly, and reorganization of myosin to stress fibers were induced by concentrations of endothelin-1 that also stimulated stellate cell contraction. BQ-123, a selective endothelin receptor antagonist, inhibited myosin phosphorylation and contractile force generation. Y-27632, which selectively inhibits rho-associated kinase, also blocked endothelin-1-stimulated myosin phosphorylation and contractile force generation with a similar dose dependence. These results suggest that endothelin-1-stimulated contractile force generation by stellate cells is mediated by myosin.