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Tobacco ringspot virus (TRSV) is a plant quarantine virus in Korea. As such, a TRSV examination is conducted when importing various crops. In this study, RT-PCR and nested PCR systems for TRSV detection in quarantine sites, and the modified-positive control plasmid for proving laboratory contamination and false positive reactions were developed. The developed diagnostic system was used to detect TRSV in the quarantine site. It revealed that from 2012 to August 2014, a total of 12 cases were detected in imported various crops. The system is expected to continue contributing to TRSV detection in plant quarantine.
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BACKGROUND: Positive end-expiratory pressure (PEEP) has been known to adversely influence cardiac output. Even though left ventricular (LV) diastolic function significantly contributes to LV performance, the effects of PEEP on LV diastolic function remains controversial. We, therefore, aimed to examine the effects of PEEP on LV diastolic function by use of pulsed wave Doppler tissue imaging in patients with pre-existing LV relaxation abnormality. METHODS: Seventeen patients with peak early diastolic velocity of lateral mitral annulus (E') <8.5 cm s(-1) among patients who underwent coronary artery bypass graft surgery were evaluated. Echocardiographic and haemodynamic variables were measured with 0, 5, and 10 cmH2O of PEEP. E' and deceleration time (DT) of peak early transmitral filling velocity (E) were used as echocardiographic indicators of LV diastolic function. RESULTS: Mean arterial blood pressure decreased during 10 cmH2O PEEP, compared with that during 0 cmH2O PEEP. E' showed a gradual and significant decrease with an incremental increase in PEEP (6.9 ± 0.9, 5.8 ± 0.9, and 5.2 ± 1.2 cm s(-1) during 0, 5, and 10 cmH2O PEEP, respectively), and DT of E was prolonged during 10 cmH2O PEEP, compared with that during 0 cmH2O PEEP. CONCLUSIONS: Increasing PEEP led to a progressive decline in LV relaxation in patients with pre-existing LV relaxation abnormality.
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Respiración con Presión Positiva/efectos adversos , Disfunción Ventricular Izquierda/diagnóstico por imagen , Anciano , Análisis de Varianza , Presión Arterial , Diástole , Ecocardiografía Doppler de Pulso/métodos , Femenino , Ventrículos Cardíacos/diagnóstico por imagen , Ventrículos Cardíacos/fisiopatología , Humanos , Masculino , Disfunción Ventricular Izquierda/etiologíaRESUMEN
Animal and/or plant protein sources substituting fishmeal in the diets keep being developed due to its high price. The purpose of this study is to determine response of dietary substitution of fishmeal with silkworm pupae meal, promate meal®, meat and bone meal and/or their combination on the performance of juvenile olive flounder. A 60% fish meal was used as the main protein source, used as the control (Con) diet. The 10 and 20% fishmeal were substituted with silkworm pupae meal and meat and bone meal, referred to as the SPM10, SPM20, MBM10 and MBM20 diets, respectively. And the 10, 20 and 40% fishmeal were substituted with promate meal®, referred to as the PM10, PM20 and PM40 diets, respectively. Finally, the 10 and 20% fishmeal were substituted with combined silkworm pupae meal and promate meal®, refereed to as the SPM + PM10 and SPM + PM20 diets, respectively. Weight gain and specific growth rate of fish fed the MBM10 diet were higher than those of fish fed the Con, SPM20, PM20, PM40 and SPM + PM20 diets. Feed efficiency ratio of fish fed the SPM10, MBM10, MBM20, PM10 and SPM + PM10 diets was higher than that of fish fed the SPM + PM20 and PM40 diets. Protein efficiency ratio of fish fed the MBM10 and MBM20 diets was higher than that of fish fed the SPM20, PM20, PM40 and SPM + PM20 diets. In conclusion, dietary substitution of fishmeal with 10% SPM, 20% MBM, 10% PM and 10% SPM + PM could be made.
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Proteínas en la Dieta/administración & dosificación , Lenguado/sangre , Lenguado/crecimiento & desarrollo , Alanina Transaminasa/sangre , Aminoácidos/análisis , Alimentación Animal/análisis , Animales , Aspartato Aminotransferasas/sangre , Glucemia/metabolismo , Proteínas Sanguíneas/metabolismo , Composición Corporal , Proteínas en la Dieta/análisis , Proteínas de Peces/administración & dosificación , Triglicéridos/sangreRESUMEN
Compensatory growth of grower olive flounder (Paralichthys olivaceus) was determined at suboptimal temperature (13.0±1.9°C). Fifteen fish averaging 201.1 g per tank were distributed into 18 of 300 L flow-through tanks. Six treatments were prepared in triplicate: fish were hand-fed with an extruded pellet to apparent satiation once a day for 16 weeks (16 WF); and the other five groups of fish were hand-fed for 15, 14, 13, 12 and 10 weeks after 1-, 2-, 3-, 4- and 6-week feed deprivation, referred to as 15 WF, 14 WF, 13 WF, 12 WF and 10 WF, respectively. A linear relationship between body weight of fish and feed deprivation was observed: Y (Body weight of fish) = -1.81X (Weeks of feed deprivation)+201.07, R(2) = 0.83. Weight gain of grower olive flounder in 15 WF, 14 WF, 13 WF and 12 WF treatments was comparable to that of fish in 16 WF treatment, but lower than that of fish in 10 WF treatment. Specific growth rate of fish in 15 WF treatment was higher than that of fish in 16 WF, 14 WF and 10 WF treatments. Feed consumption of fish was not affected by feeding regime. Feed and protein efficiency ratios of fish in 15 WF treatment were higher than those of fish in 13 WF, 12 WF and 10 WF treatments. Grower olive flounder could achieve full compensatory growth when fish were daily fed for 12 weeks after 4-week feed deprivation at suboptimal temperature.
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Use of intra-operative trans-oesophageal echocardiography (TEE) is an independent risk factor for post-operative dysphagia. This study investigated whether modifying the TEE probe-placement protocol could reduce the incidence of post-operative dysphagia. In group I (n = 100), the TEE probe was inserted after anaesthetic induction and remained in place until the completion of surgery. In group II (n = 100), the TEE probe was inserted after anaesthetic induction, the heart was examined, then the probe was removed. The probe was inserted again before weaning from cardiopulmonary bypass and then immediately removed after examination. The incidence of dysphagia was significantly higher in group I than in group II patients (51.1% versus 28.6%). Multivariate regression analysis showed that the length of time that the TEE probe was in the oesophagus was an independent predictor of dysphagia. Modification of the TEE protocol in this way can reduce the incidence of post-operative dysphagia in cardiac surgery patients.
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Trastornos de Deglución/etiología , Ecocardiografía Transesofágica/efectos adversos , Esófago/fisiopatología , Anciano , Anestesia/métodos , Procedimientos Quirúrgicos Cardíacos/efectos adversos , Trastornos de Deglución/epidemiología , Trastornos de Deglución/fisiopatología , Ecocardiografía Transesofágica/métodos , Femenino , Humanos , Incidencia , Masculino , Persona de Mediana Edad , Análisis Multivariante , Periodo Posoperatorio , Estudios Prospectivos , República de Corea , Factores de TiempoRESUMEN
BACKGROUND: Lidocaine has been demonstrated to exert cardioprotective effects against myocardial ischaemia and reperfusion injury. We evaluated whether a continuous i.v. infusion of lidocaine reduced myocardial injury in patients undergoing off-pump coronary artery bypass graft surgery (OPCAB). METHODS: In this randomized, double-blinded trial, 99 patients received i.v. lidocaine 2% (i.e. a 1.5 mg kg(-1) bolus at induction of anaesthesia followed by a 2.0 mg kg(-1) h(-1) infusion intraoperatively) or an equal volume of saline. Serum creatine kinase-myocardial band (CK-MB) and troponin I (TnI) concentrations were measured before surgery, upon arrival in the intensive care unit, and at 6, 24, 48, and 72 h after surgery. Cardiac enzymes, other biological markers, and rate of postoperative adverse events were compared between the groups. RESULTS: The median (25-75% inter-quartile range) TnI [0.90 (0.43-1.81) vs 1.71 (0.88-3.02) ng ml(-1), P=0.027] and CK-MB [6.5 (3.9-12.3) vs 9.8 (6.0-18.6) ng ml(-1), P=0.005] concentrations 24 h after surgery were significantly lower in the lidocaine group than in the control group. Moreover, lidocaine infusion reduced the total area under the curve of TnI and CK-MB release after surgery by 42% and 27%, respectively, compared with control. CONCLUSIONS: Continuous i.v. infusion of lidocaine during surgery reduces myocardial injury in patients undergoing OPCAB.
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Anestésicos Locales/uso terapéutico , Cardiotónicos/uso terapéutico , Puente de Arteria Coronaria Off-Pump/efectos adversos , Lidocaína/uso terapéutico , Daño por Reperfusión Miocárdica/prevención & control , Anciano , Biomarcadores/sangre , Cardiotónicos/administración & dosificación , Forma MB de la Creatina-Quinasa/sangre , Método Doble Ciego , Femenino , Humanos , Infusiones Intravenosas , Lidocaína/administración & dosificación , Masculino , Persona de Mediana Edad , Daño por Reperfusión Miocárdica/enzimología , Daño por Reperfusión Miocárdica/etiología , Troponina I/sangreRESUMEN
BACKGROUND: The aim of this study was to evaluate the efficacy of ondansetron and ramosetron in the reduction of post-operative nausea and vomiting (PONV) associated with patient-controlled analgesia (PCA) after cardiac surgery. METHODS: A total of 320 patients scheduled for elective cardiac surgery were enrolled. Patients were randomly assigned to one of four treatment regimens (n=80 in each group): no prophylactic antiemetics (group P); intravenous (i.v.) ondansetron 4 mg at the end of surgery and 12 mg added to PCA (group O); i.v. ramosetron 0.3 mg at the end of surgery and no antiemetics added to PCA (group R1); and i.v. ramosetron 0.3 mg at the end of surgery and 0.6 mg added to PCA (group R2). RESULTS: The incidence of PONV during the 48-h post-operative period was lower in groups O (46%), R1 (54%), and R2 (35%) compared with group P (71%, P<0.001). The incidence and severity of nausea were lower in groups O, R1, and R2 than in group P during the 24-h post-operative period, whereas the incidence and severity of nausea during 24-48 h after surgery were lower in groups O and R2, but not in group R1, than in group P. Compared with group P (53%), the frequency of rescue antiemetic usage was significantly lower in groups O (34%) and R2 (29%), but not in group R1 (43%). CONCLUSION: The addition of either ondansetron or ramosetron to PCA can reduce the incidence of PONV during 48 h after cardiac surgery.
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Antieméticos/uso terapéutico , Bencimidazoles/uso terapéutico , Procedimientos Quirúrgicos Cardíacos , Ondansetrón/uso terapéutico , Náusea y Vómito Posoperatorios/prevención & control , Anciano , Analgesia Controlada por el Paciente , Anestesia , Antieméticos/administración & dosificación , Bencimidazoles/administración & dosificación , Método Doble Ciego , Femenino , Humanos , Infusiones Intravenosas , Inyecciones Intravenosas , Masculino , Persona de Mediana Edad , Ondansetrón/administración & dosificación , Dolor Postoperatorio/epidemiología , Cuidados Posoperatorios , Náusea y Vómito Posoperatorios/diagnósticoRESUMEN
Cerebrospinal fluid (CSF) drainage is a common adjunct to thoracoabdominal aortic aneurysm (TAAA) repair. CSF drainage may improve perioperative spinal cord perfusion and thereby decrease the incidence of paraplegia or paraparesis. Complications of CSF drainage may arise. We present a case of cerebral epidural hematoma (EDH), possibly arising from excessive CSF drainage, during thoracoabdominal aortic repair.
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Aneurisma de la Aorta Torácica/cirugía , Líquido Cefalorraquídeo/fisiología , Hematoma Epidural Craneal/etiología , Complicaciones Intraoperatorias/líquido cefalorraquídeo , Niño , Humanos , Masculino , Síndrome de Marfan/complicaciones , Paresia/etiología , Complicaciones Posoperatorias/etiología , Procedimientos Quirúrgicos VascularesRESUMEN
Coronary artery bypass graft (CABG) patients often have cerebrovascular disease and pre-operative brain magnetic resonance angiography (MRA) frequently reveals cerebral vasculature stenosis. This study was designed to investigate whether pre-operative MRA findings correlated with regional cerebral oxygen saturation (ScO(2)) in 120 patients undergoing on-pump or off-pump CABG. Following MRA examination, patients were divided into six groups of 20 patients each based on MRA findings (no stenosis, mild stenosis or severe stenosis) and procedure (on-pump or off-pump CABG). Mean ScO(2) values over 3 min were determined at seven periods during surgery. Patients with severe cerebrovascular stenosis showed significantly lower ScO(2) than other groups during off-pump CABG. During on-pump CABG, ScO(2) decreased significantly during cardiopulmonary bypass in all groups and was significantly lower in the severe stenosis group. Pre-operative MRA and intra-operative ScO(2) monitoring may help to identify patients at increased risk of brain damage during or following CABG.
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Encéfalo/diagnóstico por imagen , Encéfalo/metabolismo , Puente de Arteria Coronaria , Angiografía por Resonancia Magnética , Oxígeno/metabolismo , Periodo Preoperatorio , Demografía , Femenino , Humanos , Periodo Intraoperatorio , Masculino , Persona de Mediana Edad , RadiografíaRESUMEN
Bispectral index (BIS) values derived from the left and right forehead are usually the same. We report on two patients with unilateral carotid artery stenosis in whom we observed differences between the BIS values obtained from sensors placed on each side of the forehead. During surgery, the BIS values of the diseased side decreased more than those of the opposite side when the mean arterial pressure decreased below 70 mmHg. BIS monitors should be used with caution in patients with unilateral carotid artery and cerebrovascular disease.
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Estenosis Carotídea/cirugía , Frente/irrigación sanguínea , Frente/fisiopatología , Anciano , Presión Sanguínea , Femenino , Humanos , MasculinoRESUMEN
Taste and odour problems of tap water in Seoul are attributed to 2-methylisoborneol (2-MIB) and trans-1,10-dimethyl-trans-9-decalol (geosmin), which are the result of metabolism of algae and chlorine for disinfection. This study was carried out to measure 2-MIB and geosmin in the raw water from the Han River, to investigate removal efficiency of GAC and BAC integrated with post-ozonation, and to minimise and quantify the required chlorine concentration as a final disinfectant through the candidate process.
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Canfanos/análisis , Naftoles/análisis , Odorantes/análisis , Microbiología del Agua , Purificación del Agua/métodos , Abastecimiento de Agua , Cloro/química , Cloro/farmacología , Eucariontes/metabolismo , Corea (Geográfico) , Ozono , Proyectos Piloto , Estaciones del Año , Factores de TiempoRESUMEN
BACKGROUND: There has been no longitudinal study in Taiwan to identify the nature and the scale of medical care utilization of people with intellectual disabilities (IDs) up to the present. The aim of this study is to describe inpatient utilization among people under ID care in institutions in order to identify the pattern of medical care needs and the factors affecting utilization in Taiwan. METHOD: The subject cohort was 168 individuals with ID who were cared for by a large public disability institution from 1999 to 2002 in Taipei, Taiwan. RESULTS: On the examination of the inpatient care that these persons underwent, it was found that these individuals had a heightened need (inpatient rate: 10.1-14.9%) for inpatient care compared with the general population with disabilities (9.37%) in Taiwan. The main reasons for hospitalization were pneumonia, gastrointestinal disorders, cellulites, orthopaedic problems, epilepsy and bronchitis. Using the full model of Generalized Estimating Equations for inpatient care utilization, the factors including low income family, living in an institution, being a subject with cerebral palsy and being a high outpatient user all influenced the use of inpatient care. CONCLUSIONS: This study highlights that health authorities need to promote health planning more in order to ensure an excellent quality of health monitoring and health promotion among people with ID cared for by institutions.
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Estado de Salud , Hospitalización/estadística & datos numéricos , Discapacidad Intelectual/epidemiología , Discapacidad Intelectual/rehabilitación , Evaluación de Necesidades , Adolescente , Adulto , Áreas de Influencia de Salud , Niño , Preescolar , Demografía , Femenino , Humanos , Incidencia , Lactante , Estudios Longitudinales , Masculino , Prevalencia , Taiwán/epidemiologíaRESUMEN
This study compared brain glucose metabolism during sevoflurane anaesthesia and propofol anaesthesia using positron emission tomography (PET) in the same eight human volunteers. All the volunteers were anaesthetized twice, with a 1-week interval. Half of the volunteers received sevoflurane on the first occasion and propofol on the second; the other half received the two anaesthetics in the reverse order. PET scans using 18F-fluorodeoxyglucose were performed after sevoflurane or propofol anaesthesia. The relative glucose metabolic rate (rGMR) in the brain was assessed with statistical parametric mapping. Propofol suppressed the rGMR of the neocortex area more than sevoflurane, and sevoflurane suppressed the rGMR of the paleocortex and telencephalon more than propofol. These findings suggest that these two anaesthetics act via different mechanisms and may provide an important clue to the relationship between anaesthesia and the brain.
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Anestésicos por Inhalación/farmacología , Anestésicos Intravenosos/farmacología , Corteza Cerebral/efectos de los fármacos , Glucosa/metabolismo , Éteres Metílicos/farmacología , Propofol/farmacología , Administración por Inhalación , Adulto , Presión Sanguínea/efectos de los fármacos , Mapeo Encefálico , Corteza Cerebral/metabolismo , Fluorodesoxiglucosa F18 , Frecuencia Cardíaca/efectos de los fármacos , Humanos , Infusiones Intravenosas , Masculino , Tomografía de Emisión de Positrones , Respiración/efectos de los fármacos , Sevoflurano , Telencéfalo/efectos de los fármacosRESUMEN
UNLABELLED: Nerve ligation injury may produce a pain syndrome that includes tactile allodynia. Reversal effects on tactile allodynia have been demonstrated after the intrathecal administration of gamma-aminobutyric acid (GABA) receptor agonists or cholinesterase inhibitors in rats. We examined the drug interactions between neostigmine and muscimol or baclofen in a rat model of nerve ligation injury. Rats were prepared with tight ligation of the left L5-6 spinal nerves and chronic intrathecal catheter implantation. Tactile allodynia was measured by applying von Frey filaments ipsilateral to the lesioned hindpaw. Thresholds for paw withdrawal were assessed. Neostigmine (0.3-10 microg), muscimol (0.1-10 microg), and baclofen (0.1-3.0 microg) were administered to obtain the dose-response curve and the 50% effective dose (ED(50)). Fractions of ED(50) values were administered intrathecally to establish the ED(50)s of drug combinations (neostigmine-muscimol and neostigmine-baclofen). The drug interactions were performed. Intrathecal neostigmine, muscimol, baclofen, and their combinations produced a dose-dependent increase in withdrawal threshold of the lesioned hindpaw. Both analyses revealed a synergistic interaction for the neostigmine-muscimol combination, whereas the effect of the neostigmine-baclofen combination was additive. These results suggest that the activation of both muscarinic and GABA(A) receptors is required for synergistic interaction. IMPLICATIONS: This study indicates that drug interaction is synergistic for the neostigmine-muscimol combination, whereas the effect of the neostigmine-baclofen combination is additive. In a rat model of nerve ligation injury, neostigmine, muscimol, baclofen, and their combinations provide an antagonism on touch-evoked allodynia at the spinal level.
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Baclofeno/farmacología , Inhibidores de la Colinesterasa/farmacología , Agonistas del GABA/farmacología , Muscimol/farmacología , Neostigmina/farmacología , Neuralgia/tratamiento farmacológico , Animales , Relación Dosis-Respuesta a Droga , Interacciones Farmacológicas , Hiperalgesia/tratamiento farmacológico , Hiperalgesia/etiología , Ligadura , Masculino , Neuralgia/etiología , Umbral del Dolor/efectos de los fármacos , Ratas , Ratas Sprague-Dawley , Nervios Espinales/cirugía , TactoRESUMEN
BACKGROUND AND OBJECTIVES: Nitric oxide (NO) has been implicated as one of the mediators of acute graft-versus-host disease (GVHD) but reports on its measurement during haemopoietic stem cell transplantation (HSCT) in human are scarce. The present study was conducted to measure the plasma NO in HSCT recipients in order to delineate its relationships with acute GVHD. DESIGN AND METHODS: Thirty-nine randomly selected patients undergoing HSCT were recruited. Thirty-one patients received allogeneic transplants (ALLO) from HLA-identical siblings (n=20), haploidentical parent (n=1) and matched unrelated donors (n=10). Eight patients received autologous (AUTO) HSCT. Plasma levels of nitrite/nitrate (NO(2)(-)/NO(3)(-)), the end-product of NO, were measured by chemiluminescence and the results were correlated with the occurrence and severity of acute GVHD. RESULTS: Baseline NO(2)(-)/NO(3)(-) levels before HSCT were similar in the ALLO and AUTO patients (17.4 vs 21.1 microL, p>0.05). Significant increases in plasma NO(2)(-)/NO(3)(-) (> 2 times the baseline level) were found in all 13 patients with acute GVHD > or = grade 2, in 15 out of 18 patients with acute GVHD grade < or = 1 and 3 out of 8 patients receiving autologous HSCT. The increase in NO(2)(-)/NO(3)(-) among the three groups of patients was significantly different (135.5 vs 56.3 vs 36.6 micromol/L, p < 0.001). The average NO production, calculated as the area under the curve, was also significantly differently among the three groups of patients (44.5 vs 30.0 vs 23.8 micromol/L, p < 0.001). INTERPRETATION AND CONCLUSIONS: Plasma NO in HSCT recipients is quantitatively associated with the occurrence of acute GVHD and its role remains to be determined.
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Enfermedad Injerto contra Huésped/etiología , Trasplante de Células Madre Hematopoyéticas/efectos adversos , Óxido Nítrico/sangre , Adolescente , Adulto , Anciano , Biomarcadores/sangre , Femenino , Enfermedad Injerto contra Huésped/sangre , Histocompatibilidad , Humanos , Masculino , Persona de Mediana Edad , Factores de Riesgo , Trasplante Autólogo , Trasplante HomólogoRESUMEN
We developed micropore membrane inlet mass spectrometer (MMIMS) probes to rapidly measure inert-gas partial pressures in small blood samples. The mass spectrometer output was linearly related to inert-gas partial pressure (r(2) of 0.996-1.000) and was nearly independent of large variations in inert-gas solubility in liquid samples. We infused six inert gases into five pentobarbital-anesthetized New Zealand rabbits and used the MMIMS system to measure inert-gas partial pressures in systemic and pulmonary arterial blood and in mixed expired gas samples. The retention and excretion data were transformed into distributions of ventilation-to-perfusion ratios (V(A)/Q) with the use of linear regression techniques. Distributions of V(A)/Q were unimodal and broad, consistent with prior reports in the normal rabbit. Total blood sample volume for each VA/Q distribution was 4 ml, and analysis time was 8 min. MMIMS provides a convenient method to perform the multiple inert-gas elimination technique rapidly and with small blood sample volumes.
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Análisis de los Gases de la Sangre/instrumentación , Isoflurano/análogos & derivados , Espectrometría de Masas/instrumentación , Membranas Artificiales , Relación Ventilacion-Perfusión , Acetona/análisis , Anestésicos por Inhalación/análisis , Animales , Análisis de los Gases de la Sangre/métodos , Desflurano , Enflurano/análisis , Éter/análisis , Femenino , Isoflurano/análisis , Criptón/análisis , Espectrometría de Masas/métodos , Gases Nobles/análisis , Presión Parcial , Arteria Pulmonar/fisiología , Conejos , Sensibilidad y Especificidad , Solubilidad , Hexafluoruro de Azufre/análisisRESUMEN
A community mental health assessment questionnaire relating largely to depressed mood was administered during 1972 to 1,212 respondents in Washington County, MD, by six interviewers. Analysis of 15 psycho-social tests showed that responses obtained by one interviewer differed significantly from responses obtained the other five. Suggestions for minimizing interviewer effects include 1) selection of interviewers with similar characteristics and backgrounds; 2) adequate training and periodic field assessment of interviewer performance; 3) simplification of questions and reduction in the number of possible responses per question; and 4) allocation of various types of subjects to interviewers as uniformly as possible.
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Actitud Frente a la Salud , Encuestas Epidemiológicas , Entrevista Psicológica , Encuestas y Cuestionarios , Actitud del Personal de Salud , Depresión , Encuestas Epidemiológicas/métodos , Humanos , Relaciones Interpersonales , Análisis de Regresión , MuestreoRESUMEN
The exchange of HTO with aerial portions of the soybean was studied under a variety of conditions. When fed to a lone leaf or leaflet in a saturated air atmosphere (all other leaves and the growing point having been excised), the HTO profile virtually ceases at a distance of 2 cm from the feeding chamber in the photosynthetic plant, but is greater and more extensive in the unilluminated plant. The differences are accentuated when roots are excised. Under these latter conditions the photosynthetic T-fixed gradient virtually disappears.HTO was exchanged with darkened petioles. When the rest of the shoot was kept in the light (the leaf being in a saturated H(2)O-vapor atmosphere) atmosphere) almost half the activity moves acropetally, and under these conditions (35 min, room temp) over 8% may be found in the leaf. Approximately one-tenth moves basipetally, with none being found in the stem. When the leaf is dark, no movement occurs out of the petiolar feeding chamber.An attempt was made to distinguish between sucrose transport by diffusion and mass flow of water by means of 2 mathematical models. In Model I, self-diffusion of HTO, Fick's Law was used, with the water and photosynthate moving independently. Model I consisted of an equilibrated, single pool of constant specific activity, generating a radioactive profile as a result of self-diffusion. In Model II, mass flow, water exchanged freely between the phloem and the surrounding tissues. The conducting bundle, 7790 micron(2), (0.25% of the total cross-section) was an average phloem. The numerical solution for the second model was obtained by Fortran programming on a digital computer and compared with experimental data. Comparison of these models with the experimental results suggest that mass flow is not a dominant process in soybean photosynthate translocation.
RESUMEN
Apetiolar transport of photosynthate (-14)C has been studied by feeding of (14)CO(2) to soybean petioles. Translocation occurs in the absence of leaves, but both the rate and velocity are diminished. The effect of root excision is not as profound as that of leaves. It appears, in some instances, to inhibit transport partially, so that accumulation of photosynthate develops, giving a steeper isotopic gradient. The effect of leaf darkening is to diminish its uptake of photosynthate from the petiole, possibly as a result of decreased transpiration in the lowered temperature of the darkened leaf. The data suggest that neither mass flow nor active transport provide an adequate basis for normal photosynthate transport but that the leaves provide a direct force requiring structural continuity, or a translocation carrier.