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1.
Phys Med Biol ; 62(21): 8226-8245, 2017 Oct 12.
Artículo en Inglés | MEDLINE | ID: mdl-28817383

RESUMEN

Proton range random and systematic uncertainties are the major factors undermining the advantages of proton therapy, namely, a sharp dose falloff and a better dose conformality for lower doses in normal tissues. The influence of CT artifacts such as beam hardening or scatter can easily be understood and estimated due to their large-scale effects on the CT image, like cupping and streaks. In comparison, the effects of weakly-correlated stochastic noise are more insidious and less attention is drawn on them partly due to the common belief that they only contribute to proton range uncertainties and not to systematic errors thanks to some averaging effects. A new source of systematic errors on the range and relative stopping powers (RSP) has been highlighted and proved not to be negligible compared to the 3.5% uncertainty reference value used for safety margin design. Hence, we demonstrate that the angular points in the HU-to-RSP calibration curve are an intrinsic source of proton range systematic error for typical levels of zero-mean stochastic CT noise. Systematic errors on RSP of up to 1% have been computed for these levels. We also show that the range uncertainty does not generally vary linearly with the noise standard deviation. We define a noise-dependent effective calibration curve that better describes, for a given material, the RSP value that is actually used. The statistics of the RSP and the range continuous slowing down approximation (CSDA) have been analytically derived for the general case of a calibration curve obtained by the stoichiometric calibration procedure. These models have been validated against actual CSDA simulations for homogeneous and heterogeneous synthetical objects as well as on actual patient CTs for prostate and head-and-neck treatment planning situations.


Asunto(s)
Calibración , Neoplasias/radioterapia , Protones , Planificación de la Radioterapia Asistida por Computador/métodos , Errores de Configuración en Radioterapia/prevención & control , Tomografía Computarizada por Rayos X/métodos , Artefactos , Humanos , Relación Señal-Ruido , Incertidumbre
2.
Osteoporos Int ; 27(10): 3063-71, 2016 10.
Artículo en Inglés | MEDLINE | ID: mdl-27198233

RESUMEN

UNLABELLED: Lower vitamin D and higher parathyroid hormone (PTH) levels are associated with higher volumetric BMD and bone strength at the lumbar spine as measured by central quantitative computed tomography in primary hyperparathyroidism (PHPT), but there are no differences in bone microarchitecture as measured by trabecular bone score (TBS). INTRODUCTION: The purpose of this study was to evaluate the association between 25-hydroxyvitamin D (25OHD) and volumetric bone mineral density (vBMD) and the TBS at the lumbar spine (LS) in PHPT. METHODS: This is a cross-sectional analysis of PHPT patients with and without low 25OHD. We measured vBMD with quantitative computed tomography (cQCT) and TBS by dual-energy X-ray absorptiometry (DXA) at the LS in 52 and 88 participants, respectively. RESULTS: In the cQCT cohort, those with lower vitamin D (<20 vs. 20-29 vs. ≥30 ng/ml) tended to be younger (p = 0.05), were less likely to use vitamin D supplementation (p < 0.01), and had better renal function (p = 0.03). Those with 25OHD <20 ng/ml had 80 and 126 % higher serum PTH levels respectively vs. those with 25OHD 20-29 ng/ml (p = 0.002) and 25OHD ≥30 ng/ml (p < 0.0001). Covariate-adjusted integral and trabecular vBMD were higher in those with 25OHD 20-29 vs. those with 25OHD ≥30 ng/ml, but those with 25OHD <20 did not differ. Because there were few participants with 25OHD deficiency, we also compared those with vitamin D <30 vs. ≥30 ng/ml. Covariate-adjusted integral and trabecular vBMD were 23 and 30 % higher respectively (both p < 0.05) in those with vitamin D <30 vs. ≥30 ng/ml. TBS was in the partially degraded range but did not differ by vitamin D status. CONCLUSION: In mild PHPT, lower 25OHD is associated with higher PTH, but vitamin D deficiency and insufficiency using current clinical thresholds did not adversely affect lumbar spine skeletal health in PHPT. Further work is needed to determine if higher vBMD in those with lower vitamin D is due to an anabolic effect of PTH.


Asunto(s)
Densidad Ósea , Hueso Esponjoso/patología , Hiperparatiroidismo Primario/complicaciones , Deficiencia de Vitamina D/complicaciones , Anciano , Estudios Transversales , Femenino , Humanos , Hiperparatiroidismo Primario/fisiopatología , Masculino , Persona de Mediana Edad , Hormona Paratiroidea/sangre , Vitamina D/análogos & derivados , Vitamina D/sangre , Deficiencia de Vitamina D/fisiopatología
3.
Osteoporos Int ; 26(12): 2837-43, 2015 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-26084258

RESUMEN

UNLABELLED: We compared temporal trends in serum 25-hydroxyvitamin D and parathyroid hormone (PTH) in two primary hyperparathyroidism (PHPT) cohorts recruited 20 years apart. The prevalence of 25-hydroxyvitamin D levels <20 and <30 ng/mL declined by 30-50 %, respectively, and was accompanied by lower PTH. In the older cohort, higher PTH may be due to lower 25-hydroxyvitamin D. INTRODUCTION: Vitamin D deficiency may exacerbate PHPT. Whether there have been temporal trends in 25-hydroxyvitamin D (25OHD) levels in PHPT is unclear. The prevalence of low vitamin D levels (25OHD <20 and <30 ng/mL) and associated biochemical and bone mineral density (BMD) profiles were assessed in two PHPT cohorts recruited over 20 years apart. METHODS: This is a cross-sectional comparison of serum 25OHD levels, calciotropic hormones, and BMD between two PHPT cohorts recruited at the same hospital: the "old" (N = 103) and "new" (N = 100) cohorts were enrolled between 1984 and 1991 and between 2010 and 2014, respectively. RESULTS: Mean 25OHD levels were 26 % higher in the new cohort (23 ± 10 vs. 29 ± 10 ng/mL, p < 0.0001). Levels of 25OHD <20 and <30 ng/mL declined from 46 and 82 %, respectively, to 19 and 54 % (both p < 0.0001). Supplemental vitamin D use was common in the new (64 %) but not the old cohort (0 %). The new cohort demonstrated 33 % lower serum PTH levels (p < 0.0001). Neither serum nor urine calcium differed. BMD was higher in the new cohort at all skeletal sites (all p < 0.001). CONCLUSION: With the rise in vitamin D supplementation over the last two decades, low 25OHD levels are no longer common in PHPT patients in the New York area. Those with 25OHD <20 and <30 ng/mL have declined by over 50 and 30 %, respectively. The lower mean PTH levels in the new cohort are most likely accounted for by higher vitamin D intake. Whether improved vitamin D status also underlies the relatively higher BMD in the more vitamin D replete cohort of PHPT patients is unknown.


Asunto(s)
Hiperparatiroidismo Primario/complicaciones , Deficiencia de Vitamina D/etiología , Adulto , Anciano , Densidad Ósea/fisiología , Estudios Transversales , Utilización de Medicamentos/tendencias , Femenino , Humanos , Hiperparatiroidismo Primario/sangre , Hiperparatiroidismo Primario/epidemiología , Hiperparatiroidismo Primario/fisiopatología , Masculino , Persona de Mediana Edad , New York/epidemiología , Hormona Paratiroidea/sangre , Vitamina D/análogos & derivados , Vitamina D/sangre , Vitamina D/uso terapéutico , Deficiencia de Vitamina D/sangre , Deficiencia de Vitamina D/epidemiología , Deficiencia de Vitamina D/fisiopatología
4.
J Int Med Res ; 39(5): 1890-9, 2011.
Artículo en Inglés | MEDLINE | ID: mdl-22117991

RESUMEN

This prospective, randomized, double-blind study compared the effects of dexmedetomidine and remifentanil on haemodynamic stability, sedation and postoperative pain control in the postanaesthetic care unit (PACU). Fifty consecutive patients scheduled for total laparoscopic hysterectomy were randomly assigned to receive infusions of either dexmedetomidine (1 µg/kg) i.v. over 10 min followed by 0.2 - 0.7 µg/kg per h continuous i.v. infusion or remifentanil (0.8 - 1.2 µg/kg) i.v. over 1 min followed by 0.05 - 0.1 µg/kg i.v. per min, starting at the end of surgery to the time in the PACU. Modified observer's assessment of alertness scores were significantly lower in the dexmedetomidine group than in the remifentanil group at 0, 5 and 10 min after arrival in the PACU. Blood pressure and heart rate in the dexmedetomidine group were significantly lower than that recorded in the remifentanil group in the PACU. Dexmedetomidine, at the doses used in this study, had a significant advantage over remifentanil in terms of postoperative haemodynamic stability.


Asunto(s)
Dexmedetomidina/administración & dosificación , Hipnóticos y Sedantes/administración & dosificación , Dolor Postoperatorio/prevención & control , Piperidinas/administración & dosificación , Adulto , Presión Sanguínea , Método Doble Ciego , Femenino , Frecuencia Cardíaca/efectos de los fármacos , Hemodinámica , Humanos , Histerectomía , Periodo Intraoperatorio , Laparoscopía , Persona de Mediana Edad , Dolor Postoperatorio/tratamiento farmacológico , Periodo Perioperatorio , Proyectos Piloto , Remifentanilo
5.
Environ Pollut ; 148(1): 191-200, 2007 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-17182158

RESUMEN

On an upland moor dominated by pioneer Calluna vulgaris and with an understorey of mosses and lichens, experimental plots were treated with factorial combinations of nitrogen (N) at +0 and +20kg Nha(-1)yr(-1), and phosphorus (P) at +0 and +5kg Pha(-1)yr(-1). Over the 4-year duration of the experiment, the cover of the Calluna canopy increased in density over time as part of normal phenological development. Moss cover increased initially in response to N addition but then remained static; increases in cover in response to P addition became stronger over time, eventually causing reductions in the cover of the dominant Calluna canopy. Lichen cover virtually disappeared within 4 years in plots receiving +20kg Nha(-1)yr(-1) and also in separate plots receiving +10kg Nha(-1)yr(-1), but this effect was reversed by the addition of P.


Asunto(s)
Contaminantes Atmosféricos , Calluna/crecimiento & desarrollo , Ecosistema , Fertilizantes , Nitrógeno , Fósforo , Briófitas/crecimiento & desarrollo , Ecología/métodos , Monitoreo del Ambiente/métodos , Geografía , Líquenes/crecimiento & desarrollo , Tiempo , Reino Unido
6.
Environ Pollut ; 138(3): 473-84, 2005 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-15950340

RESUMEN

This study was designed to investigate the effect of long-term (11 years) ammonium nitrate additions on standing mass, nutrient content (% and kg ha(-1)), and the proportion of the added N retained within the different compartments of the system. The results showed that more than 90% of all N in the system was found in the soil, particularly in the organic (Oh) horizon. Added N increased the standing mass of vegetation and litter and the N content (kg N ha(-1)) of almost all measured plant, litter and soil compartments. Green tissue P and K content (kg ha(-1)) were increased, and N:P ratios were increased to levels indicative of P limitation. At the lowest treatment, most of the additional N was found in plant/litter compartments, but at higher treatments, there were steep increases in the amount of additional N in the underlying organic and mineral (Eag) horizons. The budget revealed that the proportion of added N found in the system as a whole increased from 60%, 80% and up to 90% in response to the 40, 80 and 120 kg N ha(-1) year(-1) treatments, respectively.


Asunto(s)
Contaminantes Atmosféricos/toxicidad , Atmósfera/química , Nitrógeno/toxicidad , Contaminantes Atmosféricos/análisis , Contaminantes Atmosféricos/metabolismo , Biomasa , Ecosistema , Monitoreo del Ambiente/métodos , Nitrógeno/análisis , Nitrógeno/metabolismo , Fósforo/análisis , Plantas/efectos de los fármacos , Potasio/análisis , Contaminantes del Suelo/análisis , Contaminantes del Suelo/metabolismo , Contaminantes del Suelo/toxicidad
7.
Environ Pollut ; 135(3): 469-80, 2005 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-15749544

RESUMEN

This study determined the effects of increased N deposition on rates of N and P transformations in an upland moor. The litter layer and the surface of the organic Oh horizon were taken from plots that had received long-term additions of ammonium nitrate at rates of 40, 80 and 120 kg N ha(-1) yr(-1). Net mineralisation processes were measured in both field and laboratory incubations. Soil phosphomonoesterase (PME) activity and rates of N(2)O release were measured in laboratory incubations and root-surface PME activity measured in laboratory microcosms using Calluna vulgaris bioassay seedlings. Net mineralisation rates were relatively slow, with net ammonification consistently stimulated by N addition. Net nitrification was marginally stimulated by N addition in the laboratory incubation. N additions also increased soil and root-surface (PME) activity and rates of N(2)O release. Linear correlations were found between litter C:N ratio and all the above processes except net nitrification in field incubations. When compared with data from a survey of European forest sites, values of litter C:N ratio were greater than a threshold below which substantial, N input-related increases in net nitrification rates occurred. The maintenance of high C:N ratios with negligible rates of net nitrification was associated with the common presence of ericaceous litter and a mor humus layer in both this moorland as well as the forest sites.


Asunto(s)
Contaminantes Atmosféricos/análisis , Atmósfera , Calluna/química , Nitrógeno/química , Fósforo/química , Clima , Ecosistema , Monitoreo del Ambiente/métodos , Minerales , Nitrógeno/análisis , Óxido Nitroso/química , Monoéster Fosfórico Hidrolasas/química , Suelo , Contaminantes del Suelo/análisis , Gales
8.
Environ Pollut ; 121(3): 363-76, 2003.
Artículo en Inglés | MEDLINE | ID: mdl-12685765

RESUMEN

Regular applications of ammonium nitrate (35-140 kg N ha(-1) year(-1)) and ammonium sulphate (140 kg N ha(-1) year(-1)) to areas of acidic and calcareous grassland in the Derbyshire Peak District over a period of 6 years, have resulted in significant losses in both overall plant cover, and the abundance of individual species, associated with clear and dose-related increases in shoot nitrogen content. No overall growth response to nitrogen treatment was seen at any stage in the experiment. Phosphorus additions to the calcareous plots did however lead to significant increases in plant cover and total biomass, indicative of phosphorus limitation in this system. Clear and dose-related increases in soil nitrogen mineralization rates were also obtained, consistent with marked effects of the nitrogen additions on soil processes. High nitrification rates were seen on the calcareous plots, and this process was associated with significant acidification of the 140 kg N ha(-1) year(-1) treatments.


Asunto(s)
Ecosistema , Contaminación Ambiental , Nitrógeno/farmacología , Poaceae/efectos de los fármacos , Inglaterra , Fenómenos Geológicos , Geología , Fósforo/farmacología
9.
J Korean Med Sci ; 16(2): 175-82, 2001 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-11306743

RESUMEN

To determine whether the tumor cell contamination of peripheral blood stem cells influences clinical impacts on high-dose chemotherapy in patients with metastatic breast cancer, we analyzed carcinoembryonic antigen (CEA) mRNA in the apheresis products by nested RT-PCR (reverse transcriptase-polymerase chain reaction). A total of 38 metastatic breast cancer patients and ten normal healthy subjects as a negative control were included. Twenty out of 38 (51.3%) apheresis products from patients with metastatic breast cancer were positive for CEA mRNA. CEA mRNA was noted in 54.8% (17/31) of patients mobilized with chemotherapy plus G-CSF and 42.8% (3/7) of patients with G-CSF alone. There was no significant difference in age, estrogen receptor, menopausal status, mobilization method, disease free interval, or number of metastasis sites (1 vs > or = 2) between positive and negative groups. The presence of CEA mRNA in apheresis products did not influence the time to progression and overall survival in both groups. However, both the univariate and the multivariate analysis disclosed that the number of metastasis was associated with survival significantly. We suggest that the tumor cell contamination does not predict poor treatment outcome in patients with metastatic breast cancer.


Asunto(s)
Neoplasias de la Mama/tratamiento farmacológico , Neoplasias de la Mama/secundario , Trasplante de Células Madre Hematopoyéticas/efectos adversos , Adulto , Protocolos de Quimioterapia Combinada Antineoplásica/administración & dosificación , Neoplasias de la Mama/mortalidad , Antígeno Carcinoembrionario/genética , Terapia Combinada , Ciclofosfamida/administración & dosificación , Supervivencia sin Enfermedad , Doxorrubicina/administración & dosificación , Epirrubicina/administración & dosificación , Femenino , Fluorouracilo/administración & dosificación , Humanos , Persona de Mediana Edad , Análisis Multivariante , Células Neoplásicas Circulantes , Reacción en Cadena de la Polimerasa , Pronóstico , ARN Mensajero/análisis , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa
10.
Mol Pharmacol ; 58(3): 552-9, 2000 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-10953048

RESUMEN

There have been proposals that the tachykinin receptor classification should be extended to include a novel receptor, the "neurokinin-4" receptor (NK-4R), which has a close homology with the human NK-3 receptor (hNK-3R). We compared the pharmacological and molecular biological characteristics of the hNK-3R and NK-4R. Binding experiments, with (125)I-[MePhe(7)]-NKB binding to HEK 293 cell membranes transiently expressing the hNK-3R (HEK 293-hNK-3R) or NK-4R (HEK 293-NK-4R), and functional studies (Ca(2+) mobilization in the same cells) revealed a similar profile of sensitivity to tachykinin agonists and antagonists for both receptors; i.e., in binding studies with the hNK-3R, MePhe(7)-NKB > NKB > senktide >> NKA = Substance P; with the NK-4R, MePhe(7)-NKB > NKB = senktide >> Substance P = NKA; and with antagonists, SB 223412 = SR 142801 > SB 222200 >> SR 48968 >> CP 99994 for both hNK-3R and NK-4R. Thus, the pharmacology of the two receptors was nearly identical. However, attempts to isolate or identify the NK-4R gene by using various molecular biological techniques were unsuccessful. Procedures, including nested polymerase chain reaction studies, that used products with restriction endonuclease sites specific for either hNK-3R or NK-4R, failed to demonstrate the presence of NK-4R in genomic DNA from human, monkey, mouse, rat, hamster, or guinea pig, and in cDNA libraries from human lung, brain, or heart, whereas the hNK-3R was detectable in the latter libraries. In view of the failure to demonstrate the presence of the putative NK-4R it is thought to be premature to extend the current tachykinin receptor classification.


Asunto(s)
Receptores de Neuroquinina-3/metabolismo , Receptores de Taquicininas/metabolismo , Unión Competitiva , Transporte Biológico , Calcio/metabolismo , Células Cultivadas , ADN Complementario/análisis , Humanos , Reacción en Cadena de la Polimerasa , Ensayo de Unión Radioligante , Receptores de Neuroquinina-3/efectos de los fármacos , Receptores de Neuroquinina-3/genética , Receptores de Taquicininas/efectos de los fármacos , Receptores de Taquicininas/genética , Receptores de Taquicininas/aislamiento & purificación , Mapeo Restrictivo , Taquicininas/metabolismo
12.
Am J Epidemiol ; 139(9): 869-80, 1994 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-8166137

RESUMEN

Intakes of vitamin A, dietary antioxidants, and other dietary components were examined for their relation to the risk of malignant melanoma among 234 cases and 248 controls in three counties of western Washington State. Cases were drawn from persons diagnosed with melanoma between 1984 and 1987 and identified through a Seattle-Puget Sound cancer registry. Population controls were identified through random digit dialing and were randomly selected, stratified by age, sex, and county. Subjects completed a telephone interview and a mailed food frequency questionnaire asking for information on diet, demographic factors, and factors known to be associated with melanoma. Subjects were asked to estimate their food intake 7 years prior to diagnosis for cases and during a comparable time period for controls. Among data on 16 nutrients calculated from reported food intake, one significant finding emerged: Vitamin E obtained from food was inversely related to risk of melanoma (for highest quartile vs. lowest quartile, age-, education-, and energy intake-adjusted odds ratio (OR) = 0.34, 95% confidence interval (CI) 0.16-0.72; p for trend = 0.01). When intake of nutrients from food plus vitamin and mineral supplements was considered, zinc from food and supplements was associated with a decreased risk of melanoma (for highest quartile vs. lowest quartile, adjusted OR = 0.46, 95% CI 0.24-0.91; p for trend = 0.01). There was no evidence that vitamin A, preformed retinol, or carotenoids were associated with a decreased risk of melanoma or that alcohol or polyunsaturated fats were associated with an increased risk. Body mass index (weight (kg)/height (m)2) was significantly related to melanoma risk; cases were more obese than controls (for highest quartile vs. lowest quartile, age-, sex-, and education-adjusted OR = 1.90, 95% CI 1.10-3.27; p for trend = 0.02). These results provide limited support for the hypothesis that antioxidants such as vitamin E or cofactors in protection from oxidative damage such as zinc may be protective for melanoma, and they suggest that obesity should be measured in future studies of melanoma.


Asunto(s)
Dieta , Melanoma/epidemiología , Neoplasias Cutáneas/epidemiología , Vitamina E , Adulto , Anciano , Consumo de Bebidas Alcohólicas/efectos adversos , Estudios de Casos y Controles , Femenino , Humanos , Masculino , Melanoma/etiología , Persona de Mediana Edad , Obesidad/complicaciones , Factores de Riesgo , Neoplasias Cutáneas/etiología , Washingtón/epidemiología , Zinc
13.
Curr Opin Oncol ; 4(2): 347-50, 1992 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-1591307

RESUMEN

The cytogenetic features of melanoma, including the contribution of specific genes, are beginning to be unraveled. Reproductive factors have been shown to have little relationship to melanoma. The puzzles over apparent systemic effects of exposure have persisted, however. Evidence was published that the history of reaction to sun exposure altered when a diagnosis of melanoma was made. An interesting suggestion was made that the classic melanoma risk factors are associated with promotion rather than initiation of the disease. There is further evidence that exposure decreases melanoma risk in people who tan well but increases it in those who do not. Also reviewed is the evidence that the ozone layer of the stratosphere began to decrease in thickness under the influence of the chlorofluorocarbon gasses.


Asunto(s)
Melanoma/etiología , Neoplasias Cutáneas/etiología , Helioterapia/efectos adversos , Humanos , Melanoma/epidemiología , Melanoma/patología , Ozono , Salud Pública , Factores de Riesgo , Neoplasias Cutáneas/epidemiología , Neoplasias Cutáneas/patología
15.
Biofeedback Self Regul ; 2(4): 435-47, 1977 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-612355

RESUMEN

Two automatic electronic systems for tracking diastolic or systolic blood pressure (BP) and their use in biofeedback experiments are described. Both systems are based on the use of an arm cuff and the recording of Korotkoff sounds with a microphone. An electronic control system receives input from the microphone and provides output to several solenoid valves that control compressed airflow to the cuff. For one of the tracking systems we devised, the cuff is alternately inflated for 45 sec and deflated for 45 sec. During inflation, small increments and decrements in cuff pressure, based on the occurrence of Korotkoff sounds, are used to track BP. The other tracking system is slower but provides more continuous measurements: The cuff is alternately inflated to approximately the BP level for 5 sec and then deflated for 5 sec. During each inflation, the number of Korotkoff sounds is recorded by the system and according to this number, the amount of inflation on the next trial is automatically adjusted so that the cuff pressure follows BP. Both systems have been used successfully in biofeedback applications.


Asunto(s)
Sistema Nervioso Autónomo/fisiología , Biorretroalimentación Psicológica/fisiología , Determinación de la Presión Sanguínea/métodos , Presión Sanguínea , Determinación de la Presión Sanguínea/instrumentación , Humanos
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