RESUMEN
Morphological characterization of valley networks in three exposures of ancient cratered highlands (Nhc1) in the greater Meridiani Planum region yields insight into the Martian aqueous history. From our mapping, key regional differences are apparent in fine-scale valley network attributes including morphologic type, planimetric form, density, and links to candidate paleolakes. This information, combined with crater retention age (inferred exposure age), provides new details on the relative timing and nature of aqueous processes in the region. Newly identified pitted-type valley networks have morphological similarity to terrestrial pitted landforms in an evaporite setting. We interpret the pitted valley networks to reflect late-stage groundwater processes concentrated along the former fluvial conduits. Evidence from this study indicates that localized reactivation of valley networks occurred during or after exhumation of eastern Nhc1 unit.
RESUMEN
The ecteinascidin family comprises a number of biologically active compounds, containing two to three tetrahydroisoquinoline subunits. Although isolated from marine tunicates, these compounds share a common pentacyclic core with several antimicrobial compounds found in terrestrial bacteria. Among the tetrahydroisoquinoline natural products, ecteinascidin 743 (Et-743) stands out as the most potent antitumor antibiotics that it is recently approved for treatment of a number of soft tissue sarcomas. In this article, we will review the backgrounds, the mechanism of action, the biosynthesis, and the synthetic studies of Et-743. Also, the development of Et-743 as an antitumor drug is discussed.
Asunto(s)
Antineoplásicos , Dioxoles , Tetrahidroisoquinolinas , Urocordados/química , Animales , Antineoplásicos/química , Antineoplásicos/farmacología , Dioxoles/química , Dioxoles/farmacología , Biología Marina , Estructura Molecular , Tetrahidroisoquinolinas/química , Tetrahidroisoquinolinas/farmacología , TrabectedinaRESUMEN
OBJECTIVE: Cartilage injury can lead to post-traumatic osteoarthritis (PTOA). Immediate post-trauma cellular and structural changes are not widely understood. Furthermore, current cellular-resolution cartilage imaging techniques require sectioning of cartilage and/or use of dyes not suitable for patient imaging. In this study, we used multiphoton microscopy (MPM) data with FDA-approved sodium fluorescein to identify and evaluate the pattern of chondrocyte death after traumatic injury. METHOD: Mature equine distal metacarpal or metatarsal osteochondral blocks (OCBs) were injured by 30 MPa compressive loading delivered over 1 s. Injured and control sites were imaged unfixed and in situ 1 h post-injury with sodium fluorescein using rasterized z-scanning. MPM data was quantified in MATLAB, reconstructed in 3-D, and projected in 2-D to determine the damage pattern. RESULTS: MPM images (600 per sample) were reconstructed and analyzed for cell death. The overall distribution of cell death appeared to cluster into circular (n = 7) or elliptical (n = 4) patterns (p = 0.006). Dead cells were prevalent near cracks in the matrix, with only 26.3% (SE = 5.0%, p < 0.0001) of chondrocytes near cracks being viable. CONCLUSION: This study demonstrates the first application of MPM for evaluating cellular-scale cartilage injury in situ in live tissue, with clinical potential for detecting early cartilage damage. With this technique, we were able to uniquely observe two death patterns resulting from the same compressive loading, which may be related to local variability in matrix structure. These results also demonstrate proof-of-concept MPM diagnostic use in detecting subtle and early cartilage damage not detectable in any other way.
Asunto(s)
Cartílago Articular/lesiones , Animales , Cartílago Articular/patología , Muerte Celular/fisiología , Condrocitos/patología , Modelos Animales de Enfermedad , Diagnóstico Precoz , Estudios de Factibilidad , Caballos , Procesamiento de Imagen Asistido por Computador/métodos , Metacarpo/lesiones , Metacarpo/patología , Huesos Metatarsianos/lesiones , Huesos Metatarsianos/patología , Microscopía de Fluorescencia por Excitación Multifotónica/métodos , Estrés Mecánico , Soporte de PesoRESUMEN
We used high-density oligonucleotide microarrays to analyse the genomes and meiotic expression patterns of two yeast strains, SK1 and W303, that display distinct kinetics and efficiencies of sporulation. Hybridization of genomic DNA to arrays revealed numerous gene deletions and polymorphisms in both backgrounds. The expression analysis yielded approximately 1,600 meiotically regulated genes in each strain, with a core set of approximately 60% displaying similar patterns in both strains. Most of these (95%) are MATa/MATalpha-dependent and are not similarly expressed in near-isogenic meiosis-deficient controls. The transcript profiles correlate with the distribution of defined meiotic promoter elements and with the time of known gene function.
Asunto(s)
Meiosis/genética , Saccharomycetales/citología , Saccharomycetales/genética , Sitios de Unión/genética , Eliminación de Gen , Regulación Fúngica de la Expresión Génica , Genoma Fúngico , Cinética , Análisis de Secuencia por Matrices de Oligonucleótidos , Polimorfismo Genético , Regiones Promotoras Genéticas , ARN de Hongos/genética , ARN Mensajero/genética , Saccharomycetales/fisiología , Especificidad de la Especie , Esporas Fúngicas/genética , Factores de Transcripción/metabolismo , Transcripción GenéticaRESUMEN
BACKGROUND: As most children with acute lymphoblastic leukaemia (ALL) achieve long-term survival, minimising late effects of treatment is a priority. Acute lymphoblastic leukaemia survivors treated historically with protocols including cranial irradiation demonstrate increased weight gain. METHODS: We retrospectively studied all 134 patients treated on the MRC/UKALL97 protocol (without cranial irradiation as standard therapy) at a single centre, with 77 inclusions. Height-, weight- and body mass index (BMI) standard-deviation scores (SDS) were recorded at diagnosis and annually until 3 years out (YO) from end of treatment (EoT); changes across time were explored using a univariate model (significance P ≤ 0.001 to account for multiple comparisons). RESULTS: Whole-group height SDS was lower from 1 year into treatment until 2 YO, whereas weight- and BMI-SDS remained higher until 3 YO. In females, height-SDS was lower until EoT, but higher weight- and BMI-SDS persisted until 3 YO. In males, height-SDS was lower at EoT and at 2 YO; differences in BMI-SDS had resolved by 2 YO. By WHO criteria, more patients were overweight or obese at 3 YO than at diagnosis (P=0.01). CONCLUSION: Survivors of childhood ALL, particularly females, exhibit adverse changes in height-, weight- and BMI-SDS, which arise during treatment and persist into follow-up. Patients should be supported with appropriate dietary and lifestyle advice during ALL treatment and follow-up, which may minimise these changes and reduce associated long-term morbidity.
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Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Estatura , Índice de Masa Corporal , Peso Corporal , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamiento farmacológico , Sobrevivientes , Adolescente , Niño , Preescolar , Irradiación Craneana , Femenino , Estudios de Seguimiento , Humanos , Lactante , Masculino , Obesidad/etiología , Factores SexualesRESUMEN
Many multiphoton imaging applications would benefit from a larger field of view; however, large field of views (>mm) require low magnification objectives which have low light collection efficiencies. We demonstrate a light collection system mounted on a low magnification objective that increases fluorescence collection by as much as 20-fold in scattering tissues. This peripheral detector results in an effective numerical aperture of collection >0.8 with a 3-4 mm field of view.
Asunto(s)
Microscopía Fluorescente/métodos , Patología/métodos , Neoplasias Abdominales/patología , Animales , Encéfalo/citología , Carcinoma/patología , Ratones , Médula Espinal/citologíaRESUMEN
Concanavalin A- or phytohemagglutinin-stimulated DNA synthetic responses of 1 million normal mouse spleen cells in vitro were significantly different among various inbred strains. BALB/cJ (H-2(d)) responded better than C57BL/6J (H-2(b)) spleen cells, and the responses of C3H/HeJ or AKR/J (both H-2(k)) cells were intermediate. These responses, measured as the increment in thymidine-(3)H incorporation of mitogen-stimulated compared with unstimulated cultures, varied according to the number of cells cultured or the mitogen concentration. BALB/c spleens had the highest proportion of theta-positive cells, but no direct relationship between the proportion of theta-positive cells and the DNA synthetic response was observed. (BALB/cJ x C57BL/6)F(1) spleen cells responsed as well as BALB/c cells. Responses of spleen cells from (F(1) x C57BL/6) backcross littermates varied over a range equal to, or greater than, that of BALB/c and C57BL/6 cells. There was no correlation between H-2 specificity (H-2(bd) or H-2(bb)) or sex and the mitogen-stimulated DNA synthetic response of backcross animals. Con A- and PHA-stimulated responses of individual backcross animals were positively correlated with the level of thymidine-(8)H incorporation by unstimulated spleen cells. These results are consistent with autosomal dominant, non-H-2-linked, polygenic control of the mitogen-stimulated in vitro DNA synthetic response of mouse spleen cells.
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ADN/biosíntesis , Lectinas/farmacología , Ratones Endogámicos/metabolismo , Bazo/metabolismo , Animales , Células Productoras de Anticuerpos , Células Cultivadas , Concanavalina A/farmacología , Cruzamientos Genéticos , Pruebas Inmunológicas de Citotoxicidad , Femenino , Genes Dominantes , Inmunogenética , Técnicas In Vitro , Masculino , Ratones , Ratones Endogámicos/inmunología , Bazo/citología , Estimulación Química , Timidina/metabolismo , Timo/citología , TritioRESUMEN
Experimental allergic encephalomyelitis (EAE) was induced in rats of various genotypes by injection of 10 microg guinea pig basic protein in complete Freund's adjuvant containing 100 microg H(37) RV M. tuberculosis. Histologically verified EAE was present in 20/20 Lewis, 17/17 (Lewis x BN)F(1), 9/9 Lewis backcross, and 21/42 BN backcross rats. Among the BN backcross animals, 25/42 were determined to carry the major histocompatibility type characteristic of the Lewis strain and 21 of these had EAE. Separate groups of Lewis, BN, and (Lewis x BN)F(1) rats were immunized as described and skin tested on day 13 with 10 microg guinea pig basic protein and rat S basic protein. Animals of each genotype had Arthus and delayed skin reactivity to both antigens. These data are compatible with the hypothesis that susceptibility to EAE in rats is controlled by an autosomal dominant gene linked to the major histocompatibility locus. It is proposed that this is an immune response gene, designated Ir-EAE, which controls T cell reactivity directed against a highly encephalitogenic portion of the basic protein molecule.
Asunto(s)
Encefalomielitis Autoinmune Experimental/inmunología , Genes , Ligamiento Genético , Histocompatibilidad , Animales , Reacción de Arthus , Enfermedades Autoinmunes/inmunología , Modelos Animales de Enfermedad , Encefalomielitis Autoinmune Experimental/etiología , Encefalomielitis Autoinmune Experimental/patología , Femenino , Adyuvante de Freund , Hipersensibilidad Tardía , Masculino , Mycobacterium tuberculosis , Proteína Básica de Mielina , Fenotipo , Ratas , Ratas Endogámicas BN , Ratas Endogámicas Lew , Pruebas Cutáneas , Linfocitos T/inmunologíaRESUMEN
The BB rat develops a syndrome of autoimmune diabetes similar to Type I diabetes of man. It also has a severe T cell lymphopenia. As part of an ongoing breeding program to transfer the diabetogenic genes of the BB rat onto inbred rat strain backgrounds, diabetic animals were used in a backcross (BC)- intercross (IC)-backcross breeding scheme with Brown Norway (BN), Lewis (L), and Wistar-Furth (WF) inbred rats. We have used monoclonal antibodies to analyze both lymphopenia and major histocompatibility (MHC) antigens (the RT1 locus in the rat) in relation to the development of diabetes. To examine T cell subsets we used a panel of monoclonal antibodies, in particular W3/25 and OX19 , which discriminate the abnormal phenotype better than W3/13. In our breeding program, at least two independent genes or gene complexes are required for the expression of diabetes. One gene determines the lymphopenia, is inherited by simple autosomal recessive genetics and is not linked to the MHC. The second gene is linked to the MHC. Both genes are necessary, but neither gene is sufficient by itself for the development of diabetes.
Asunto(s)
Cruzamiento , Diabetes Mellitus Experimental/genética , Animales , Anticuerpos Monoclonales , Enfermedades Autoinmunes , Diabetes Mellitus Experimental/inmunología , Epítopos/análisis , Antígenos de Histocompatibilidad/análisis , Linfopenia/complicaciones , Complejo Mayor de Histocompatibilidad , Ratas , Ratas Endogámicas Lew , Ratas Endogámicas WF , Linfocitos T/inmunologíaRESUMEN
BACKGROUND: Reduced insulin sensitivity and increased fat mass have been reported in children and adults with congenital adrenal hyperplasia (CAH). To understand the potential mechanisms underlying these differences, we assessed insulin sensitivity and body composition in children with classical or nonclassical (late-presenting) CAH compared with normal controls. SUBJECTS AND METHODS: Thirty-seven children with CAH (26 classical and 11 nonclassical) median (range) age 9.4 year (0.5-15.8) were compared with 41 healthy control children age 11.0 year (3.2-17.1). All children had an overnight fasting blood sample and body composition assessed by DEXA. Pubertal children (14 CAH and 19 controls) also had an oral glucose tolerance test. Classical and nonclassical CAH groups were each compared with controls, adjusting for age, gender and pubertal status. Results Classical CAH children had more fat mass than controls (P = 0.03), while nonclassical CAH children had more lean mass (P = 0.006) and higher systolic blood pressure (P = 0.003) than control children. Among pubertal children, nonclassical CAH children had higher mean insulin (0-120 min; P = 0.04), stimulated insulin (0-30 min; P = 0.02), 120 min insulin (P = 0.004) and 120 min glucose levels (P = 0.03) than controls, but no difference in disposition index. DISCUSSION: Greater body fat in classical (early-presenting) CAH children could reflect the effects of lifetime glucocorticoid therapy. In contrast, the greater lean mass and parameters of insulin resistance in nonclassical (late-presenting) CAH children likely indicate the adverse metabolic effects of prolonged postnatal androgen excess.
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Hiperplasia Suprarrenal Congénita/metabolismo , Composición Corporal/fisiología , Resistencia a la Insulina/fisiología , Adolescente , Hiperplasia Suprarrenal Congénita/sangre , Glucemia/metabolismo , Presión Sanguínea/fisiología , Índice de Masa Corporal , Niño , Preescolar , Ayuno/fisiología , Femenino , Prueba de Tolerancia a la Glucosa , Humanos , Lactante , Insulina/metabolismo , MasculinoRESUMEN
BACKGROUND: Owners' perceptions and priorities regarding quality of life (QoL) are important considerations given the unknown efficacy of many commonly administered medications, stress of hospital visits, difficulties providing home care, and personal choices including euthanasia. OBJECTIVE: To describe the relative importance of quality versus quantity of life to owners of cats with heart disease. ANIMALS: Two hundred and thirty-nine cats with heart disease. METHODS: Prospective questionnaire-based clinical study. Cat owners completed a questionnaire to identify important parameters when assessing their cat's QoL, the relative importance of quality versus quantity of life, and willingness to trade survival time for QoL. Variables associated with these parameters were evaluated with multivariate analyses. RESULTS: Appetite, owner interaction, sleep patterns, and litterbox habits were deemed important to QoL. Concern over pet suffering was significantly greater than concern over life expectancy. Ninety-three percent of owners were willing to trade survival time for good QoL; 57% of these were willing to trade up to 6 months. On multivariate analysis, the only factor significantly (P=.002) associated with willingness to trade 6 months was study site. Owner concern regarding stress of administering medications at home increased with number and frequency of medications. CONCLUSIONS AND CLINICAL RELEVANCE: These results indicated that QoL is more important to owners of cats with heart disease than longevity. The various priorities and concerns of cat owners should be taken into account in order to provide optimal care.
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Enfermedades de los Gatos/psicología , Cardiopatías/veterinaria , Calidad de Vida , Bienestar del Animal , Animales , Gatos , Recolección de Datos , Femenino , Cardiopatías/psicología , Humanos , Masculino , Propiedad , Satisfacción del Paciente , Encuestas y CuestionariosRESUMEN
Tryptophan and serotonin were imaged with infrared illumination by three-photon excitation (3PE) of their native ultraviolet (UV) fluorescence. This technique, established by 3PE cross section measurements of tryptophan and the monoamines serotonin and dopamine, circumvents the limitations imposed by photodamage, scattering, and indiscriminate background encountered in other UV microscopies. Three-dimensionally resolved images are presented along with measurements of the serotonin concentration ( approximately 50 mM) and content (up to approximately 5 x 10(8) molecules) of individual secretory granules.
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Gránulos Citoplasmáticos/química , Microscopía Fluorescente/métodos , Fotones , Serotonina/análisis , Animales , Supervivencia Celular , Dopamina/análisis , Rayos Láser , Microscopía Fluorescente/instrumentación , Fotoquímica , Ratas , Triptófano/análisis , Células Tumorales Cultivadas , Rayos UltravioletaRESUMEN
Male hybrids from a cross between female mice of strain C57BL/6Kh and males of strain DBA/2J lived longer after injection of P815 mastocytoma cells of DBA/2 origin than did their female siblings. Responses to the histocompatibility antigen on the X chromosome of the DBA/2 strain may be involved in resistance to the tumor. When the female parent was replaced with a C57BL/6Kh carrying one of several mutations in the H-2 region, this sex effect disappeared in some of the hybrid combinations. Thus, the H-2 complex appears to be involved in the regulation of the immune response to the X-linked histocompatibility antigen in this tumor model.
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Antígenos H-2/inmunología , Sarcoma de Mastocitos/inmunología , Cromosomas Sexuales/inmunología , Cromosoma X/inmunología , Animales , Femenino , Humanos , Inmunidad Innata , Masculino , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Endogámicos DBA , Trasplante de Neoplasias , Factores SexualesRESUMEN
Severe diabetes with insulitis was produced in young diabetes-prone BB/W rats by passive transfer of concanavalin A-treated spleen cells from BB/W animals with acute diabetes. Spleen cells alone or in combination with lymph node cells were active in transferring disease.
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Diabetes Mellitus/inmunología , Animales , Concanavalina A/farmacología , Diabetes Mellitus/etiología , Hiperglucemia/etiología , Hiperglucemia/inmunología , Inmunidad Celular , Ratones , Ratones Desnudos , Ratas , Bazo/citología , Bazo/efectos de los fármacos , Bazo/trasplante , Trasplante Heterólogo , Trasplante HomólogoRESUMEN
Injections of rabbit antiserum to rat lymphocytes reversed hyperglycemia in 36 percent of spontaneously diabetic rats (Bio Breeding/Worcester) and prevented diabetes in susceptible nondiabetic controls. These findings strengthen the hypothesis that cell-mediated autoimmunity plays a role in the pathogenesis of diabetes in this animal model that mimics many morpholigic and physiologic characteristics of human insulin-dependent diabetes mellitus.
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Suero Antilinfocítico/uso terapéutico , Enfermedades Autoinmunes , Diabetes Mellitus Experimental/inmunología , Linfocitos/inmunología , Animales , Glucemia/metabolismo , Diabetes Mellitus Experimental/prevención & control , Diabetes Mellitus Experimental/terapia , Terapia de Inmunosupresión , Islotes Pancreáticos/inmunología , Isoanticuerpos , RatasRESUMEN
Loading of the lithosphere of Mars by the Tharsis rise explains much of the global shape and long-wavelength gravity field of the planet, including a ring of negative gravity anomalies and a topographic trough around Tharsis, as well as gravity anomaly and topographic highs centered in Arabia Terra and extending northward toward Utopia. The Tharsis-induced trough and antipodal high were largely in place by the end of the Noachian Epoch and exerted control on the location and orientation of valley networks. The release of carbon dioxide and water accompanying the emplacement of approximately 3 x 10(8) cubic kilometers of Tharsis magmas may have sustained a warmer climate than at present, enabling the formation of ancient valley networks and fluvial landscape denudation in and adjacent to the large-scale trough.
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Dióxido de Carbono , Evolución Planetaria , Marte , Agua , Atmósfera , Medio Ambiente Extraterrestre , GravitaciónRESUMEN
AIMS: This open-label prospective phase I/II dose-escalation study determined the maximum tolerated dose (MTD) and then evaluated response, safety and feasibility of a novel combination of docetaxel, cisplatinum and capecitabine (DCC) in chemotherapy-naive patients with advanced oesophago-gastric carcinoma. MATERIALS AND METHODS: Patients with adenocarcinoma or squamous cell carcinoma of the oesophagus or stomach, of good performance status, deemed too advanced for curative treatment, were given systematically increasing doses of 3 weekly DCC to ascertain the MTD. Phase II administered up to six cycles of DCC at the MTD, assessing response and toxicity. RESULTS: Between November 2007 and November 2012, 15 patients were recruited into phase I and 41 into phase II. The MDT was a 21 day cycle of docetaxel 60 mg/m2 IV day 1, cisplatinum 60 mg/m2 IV day 1 and oral capecitabine 1000 mg/m2 daily in two divided doses for days 1-21. The most common phase II grade 3-4 toxicities were neutropenia 88% (10% febrile neutropenia), fatigue 15%, sensory neuropathy 10% and non-neutropenic infection 10%. The overall response rate was 51%, median progression-free survival was 7.4 months (confidence interval 6.7-9.4) and median overall survival was 10.9 months (confidence interval 7.7-13.7). CONCLUSION: DCC was tolerable and feasible with promising efficacy, and may be suitable for future investigation in both first-line metastatic and neoadjuvant settings.
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Adenocarcinoma/tratamiento farmacológico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Carcinoma de Células Escamosas/tratamiento farmacológico , Neoplasias Esofágicas/tratamiento farmacológico , Neoplasias Gástricas/tratamiento farmacológico , Adulto , Anciano , Capecitabina/administración & dosificación , Capecitabina/efectos adversos , Cisplatino/administración & dosificación , Cisplatino/efectos adversos , Docetaxel/administración & dosificación , Docetaxel/efectos adversos , Femenino , Humanos , Masculino , Dosis Máxima Tolerada , Persona de Mediana Edad , Estudios ProspectivosRESUMEN
Autoimmune diabetes can be transferred to young, diabetes prone BB/W rats by injecting them intravenously with concanavalin A (Con A)-treated spleen cells from acute diabetic BB/W donors. This study describes the transfer of diabetes to the normal Wistar-Furth strain of rats using a similar procedure. For the successful transfer of diabetes it was necessary to immunosuppress recipient animals with a single intraperitoneal injection of cyclophosphamide 24-48 h before administering Con A-stimulated spleen cells from acute diabetic BB/W rats. Of 68 Wistar-Furth rats in immunosuppressed with a dose of 100-150 mg cyclophosphamide/kg body wt, 10 (15%) became diabetic. None of the control rats receiving either Con A-stimulated Wistar-Furth spleen cells (n = 28), freshly isolated BB/W spleen cells (n = 14), or fresh RPMI medium (n = 11) became diabetic. These data indicate that diabetes can be transferred from BB/W to Wistar-Furth rats. In addition, they support the hypothesis that cell-mediated immune processes are involved in the development of insulin-dependent diabetes and rule out any absolute requirement for BB-derived genes in the target pancreatic beta cells.
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Enfermedades Autoinmunes/transmisión , Diabetes Mellitus Experimental/inmunología , Diabetes Mellitus Tipo 1/inmunología , Animales , Células Cultivadas , Ciclofosfamida/farmacología , Diabetes Mellitus Experimental/transmisión , Diabetes Mellitus Tipo 1/transmisión , Femenino , Inmunización Pasiva , Terapia de Inmunosupresión , Masculino , Ratas , Ratas Endogámicas WF , Ratas Mutantes , Bazo/citologíaRESUMEN
PURPOSE: A systematic review was conducted to evaluate the effectiveness of workplace rehabilitation interventions for injured workers with low back pain (LBP). METHOD: MEDLINE, CINAHL (Cumulative Index to Nursing and Allied Health Literature), EMBASE, and AMED (Allied and Complementary Medicine) were searched from 1982 to 2005 for peer-reviewed studies of rehabilitation interventions that were provided at the workplace to workers with musculoskeletal work-related LBP. Methodological quality appraisal and data extraction were conducted by five reviewers. RESULTS: Of a total of 1,224 articles that were identified by the search, 15 articles, consisting of 10 studies, were of sufficient quality to be included in the review. The best evidence was that clinical interventions with occupational interventions as well as early return to work/modified work interventions were effective in returning workers to work faster, reducing pain and disability, and decreasing the rate of back injuries. Ergonomic interventions also were found to be effective workplace interventions. CONCLUSION: The need for further research in this area is necessary to reduce the burden of back pain on employees and their families, employers, and the health care system.
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Dolor de la Región Lumbar/rehabilitación , Enfermedades Profesionales/rehabilitación , Ergonomía , Ejercicio Físico , HumanosRESUMEN
This paper describes the generation of 39Ar, via reactor irradiation of potassium carbonate, followed by quantitative analysis (length-compensated proportional counting) to yield two calibration standards that are respectively 50 and 3 times atmospheric background levels. Measurements were performed in Pacific Northwest National Laboratory's shallow underground counting laboratory studying the effect of gas density on beta-transport; these results are compared with simulation. The total expanded uncertainty of the specific activity for the ~50× 39Ar in P10 standard is 3.6% (k=2).