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1.
Opt Express ; 31(25): 41014-41025, 2023 Dec 04.
Artículo en Inglés | MEDLINE | ID: mdl-38087510

RESUMEN

In recent years, significant progress has been made in the fields of nonlinear and ultrafast optics, offering exciting opportunities for terahertz (THz) science and technology. In this study, we present a novel design of a SSBCD (Solid-State-Biased Coherent Detection) device for the coherent detection of ultra-broadband THz pulses. By increasing the number of cross-fingers, we have effectively enhanced the sensitivity of the SSBCD device. The design of stepped and circular structures has successfully expanded the detectable electric field directions while reducing the dependence on the incident field direction. As a result, we have achieved ultra-broadband detection with a high dynamic range and a wide detection angle. These research findings lay a critical foundation for the integration of solid-state ultra-broadband detection into compact and miniaturized terahertz systems.

2.
Epidemiol Infect ; 147: e94, 2019 01.
Artículo en Inglés | MEDLINE | ID: mdl-30869016

RESUMEN

Gender inequality has severe consequences on public health in terms of delay in diagnosis of pulmonary tuberculosis (PTB). In order to explore gender-related differences in diagnosis delay, a cross-sectional study of 10 686 patients diagnosed with PTB in Yulin from 1 January 2009 to 31 December 2014 was conducted. Diagnosis delay was categorised into 'short delay' and 'long delay' by four commonly used cut-off points of 14, 30, 60 and 90 days. Logistic regression analysis was used to analyse gender differences in diagnostic delay. Stratified analyses by smear results, age, urban/rural were performed to examine whether the effect persisted across the strata. The median delay was 31 days (interquartile range 13-65). Diagnostic delay in females at cut-off points of 14, 30, 60 and 90 days had odds ratios (OR) of 0.99 (95% CI 0.91-1.09), 1.09 (95% CI 1.01-1.18), 1.15 (95% CI 1.05-1.26) and 1.18 (95% CI 1.06-1.31), respectively, compared with males. Stratified analysis showed that females were associated with increased risk of longer delay among those aged 30-60 years, smear positive and living in the rural areas (P < 0.05). The female-to-male OR increased along with increased delay time. Further inquiry into the underlying reasons for gender differences should be urgently addressed to improve the current situation.


Asunto(s)
Diagnóstico Tardío/estadística & datos numéricos , Tuberculosis Pulmonar/diagnóstico , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , China , Estudios Transversales , Femenino , Humanos , Masculino , Persona de Mediana Edad , Población Rural/estadística & datos numéricos , Factores Sexuales , Factores de Tiempo , Población Urbana/estadística & datos numéricos , Adulto Joven
3.
Sci Rep ; 13(1): 14487, 2023 Sep 02.
Artículo en Inglés | MEDLINE | ID: mdl-37660183

RESUMEN

The transient photocurrent is one of the key parameters of the spatial radiation effect of photoelectric devices, and the energy level defect affects the transient photocurrent. In this paper, by studying the deep level transient spectrum of a self-designed Schottky diode, the defect properties of the interface region of the anode metal AlCu and Si caused by high-temperature annealing at 150 â„ƒ, 200 â„ƒ and 300 â„ƒ for 1200 h have been quantitatively analyzed. The study shows that the defect is located at the position of + 0.41 eV on the valence band, the concentration is 2.8 [Formula: see text] 1013/cm2, and the capture cross section is [Formula: see text] = 8.5 [Formula: see text] 1017. The impurity energy level mainly comes from the diffusion of Al atom in anode metal. We found that the defect did not cause the electrical performance degradation and obvious morphology change of the device, but the transient photocurrent increased significantly. The reason is that the high temperature treatment results in a growth in the density of states at the interface between AlCu-Si. The more mismatched dislocations and recombination center increased the reverse current of the heterojunction. The above view is proved by the TCAD simulation test.

4.
New Microbes New Infect ; 42: 100905, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-34031638

RESUMEN

The coronavirus disease (COVID-19) is a novel emerging infectious disease spreading worldwide. To further understand the disease, we compared its clinical characteristics, symptoms and outcomes by gender. In an analysis of public surveillance data of Taiwan from January 21 to April 18, 2020, a total of 398 patients were diagnosed with COVID-19 by the detection of severe acute respiratory syndrome coronavirus 2 in pharynx swabs. We divided the patients into two groups: men and women. The associated data were collected, and multivariate comparisons of radiographic infiltration were conducted to analyse the gender-based differences. The mean incubation period was 5.4 ± 5 days, and the incubation period in men was 3.2 days longer than that in women (8 ± 8.1 vs. 4.8 ± 3, p = 0.05). The male patients with COVID-19 with infiltration in chest X-rays (CXR) were 12 years older than their female counterparts. The mortality rate in the male patients with COVID-19 was 6.4-fold higher than that in the female patients (3.2% vs. 0.5%, p < 0.05). The patients with comorbidities of diabetes mellitus and hypertension were vulnerable to infiltration in CXR and the patients with COVID-19 who had infiltration in CXR easily ended up with intubation, intensive care unit admission and mortality. Moreover, female patients with COVID-19 who had fever, cough and dyspnoea were susceptible to infiltration in CXR. Irrespective of whether the cases were imported female from Europe, America or Asia, indigenous male, the factors associated with death in patients with severe COVID-19 were male sex, elderly, female with fever, cough, dyspnoea and DM.

5.
Clin Transl Oncol ; 21(5): 596-606, 2019 May.
Artículo en Inglés | MEDLINE | ID: mdl-30284230

RESUMEN

PURPOSE: The purpose of our study was to investigate an underlying mechanism that hydrogen peroxide-induced mitophagy contributed to laryngeal cancer cells survivals under oxidative stress condition. METHODS: Tumor tissue and serum samples were collected from patients with laryngeal cancer. The Hep2 cell, a human laryngeal carcinoma cell, was used in in vitro experiments. The levels of lipid peroxidation were analyzed by ELISA. Knockdown of FUNDC1 was performed by RNAi. The changes of target proteins were determined by qRT-PCR and western blot. The cells were analyzed for changes in proliferation using cell counting kit-8 and mitophagy by the mitochondrial membrane potential assay and transmission electron microscopy. RESULTS: FUNDC1 in laryngeal cancer tissues were relative to the levels of lipid peroxidation in laryngeal cancer patients, which suggested that FUNDC1 was associated with the status of oxidative stress in the laryngeal cancer patients. Hydrogen peroxide significantly induced the elevation of FUNDC1, a mitophagic factor, in a time- and dose-dependent manner in laryngeal cancer cells, which was dependent on ERK signal activation. Knockdown of FUNDC1 by the siRNA attenuated the survival of laryngeal cancer cells under hydrogen peroxide stimulation. Moreover, the elevated FUNDC1 was required for the occurrence of mitophagy under hydrogen peroxide stimulation, which was identified by transmission electron microscopy, the alterations of mitochondrial permeability transition and the specific mitochondrial protein, hsp60. Inhibition of mitophagy with cyclosporine A could also effectively attenuate the laryngeal cancer cells survival under hydrogen peroxide stimulation. CONCLUSIONS: Hydrogen peroxide upregulated the expression of FUNDC1 through the activation of ERK1/2 signal to trigger a mitophagic response, giving laryngeal cancer cells a befit for survival. These findings suggested that FUNDC1 might be a potential target for the treatment of laryngeal cancer accompanied with high lipid peroxidation status.


Asunto(s)
Regulación Neoplásica de la Expresión Génica , Peróxido de Hidrógeno/farmacología , Neoplasias Laríngeas/patología , Peroxidación de Lípido , Proteínas de la Membrana/metabolismo , Mitocondrias/patología , Proteínas Mitocondriales/metabolismo , Mitofagia , Biomarcadores de Tumor/genética , Biomarcadores de Tumor/metabolismo , Estudios de Casos y Controles , Supervivencia Celular , Estudios de Seguimiento , Humanos , Neoplasias Laríngeas/genética , Neoplasias Laríngeas/metabolismo , Proteínas de la Membrana/genética , Mitocondrias/metabolismo , Proteínas Mitocondriales/genética , Oxidantes/farmacología , Fosforilación , Pronóstico , Células Tumorales Cultivadas
6.
Oncoimmunology ; 5(9): e1214788, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27757312

RESUMEN

The anti-PD-1 antibodies nivolumab and pembrolizumab are active in metastatic melanoma; however, there is limited data on combining anti-PD-1 antibody and radiotherapy (RT). We sought to review clinical outcomes of patients receiving RT and anti-PD-1 therapy. All patients receiving anti-PD-1 antibody and RT for metastatic melanoma were identified. RT and systemic treatment, clinical outcome, and toxicity data were collected. Fifty-three patients were included; 35 patients received extracranial RT and/or intracranial stereotactic radiosurgery (SRS) and 21 received whole brain radiotherapy (WBRT) (three of whom also received SRS/extracranial RT). Patients treated with extracranial RT or SRS received treatment either sequentially (RT then anti-PD-1, n = 11), concurrently (n = 16), or concurrent "salvage" treatment to lesions progressing on anti-PD-1 therapy (n = 15). There was no excessive anti-PD-1 or RT toxicity observed in patients receiving extracranial RT. Of six patients receiving SRS, one patient developed grade 3 radiation necrosis. In 21 patients receiving WBRT, one patient developed Stevens-Johnson syndrome, one patient developed acute neurocognitive decline, and one patient developed significant cerebral edema in the setting of disease. Response in irradiated extracranial/intracranial SRS lesions was 44% for sequential treatment and 64% for concurrent treatment (p=0.448). Likewise there was no significant difference between sequential or concurrent treatment in lesional response of non-irradiated lesions. For progressing lesions subsequently irradiated, response rate was 45%. RT and anti-PD-1 antibodies can be safely combined, with no detectable excess toxicity in extracranial sites. WBRT and anti-PD-1 therapy is well tolerated, although there are rare toxicities and the role of either anti-PD-1 or WBRT in the etiology of these is uncertain.

7.
Biochim Biophys Acta ; 1211(2): 234-8, 1994 Mar 03.
Artículo en Inglés | MEDLINE | ID: mdl-8117752

RESUMEN

The effect of ethanol on hepatic lipoprotein secretion is not fully understood. This study shows that exposure of HepG2 cells to ethanol significantly increases intracellular apolipoprotein B, apo B mRNA and secreted apolipoprotein B. No other agent has been shown to produce such an increase in apolipoprotein B synthesis or apolipoprotein B mRNA levels.


Asunto(s)
Apolipoproteínas B/biosíntesis , Etanol/farmacología , Hígado/metabolismo , Apolipoproteínas B/genética , Apolipoproteínas B/metabolismo , Hepatoblastoma , Humanos , Hígado/efectos de los fármacos , Neoplasias Hepáticas , ARN Mensajero/metabolismo , Células Tumorales Cultivadas
8.
Plant Physiol ; 101(3): 965-968, 1993 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-12231748

RESUMEN

Hypocotyl elongation of pakchoi (Brassica chinensis cv Lei-Choi) was stimulated by applying 300 ng of brassinosteroid (2[alpha],3[alpha],22[beta],23[beta]-tetrahydroxy-24[beta]-methyl-B-homo-7- oxa-5[alpha]-cho-le stan-6-one, BR) in 1 [mu]L of 50% ethanol to the apex of hypocotyls. BR had its greatest effect on elongation of the apical 3-mm region below the cotyledonary node (75% stimulation) between 6 and 18 h after treatment. Stress/strain (Instron) analysis of this 3-mm region revealed that plastic and elastic components of extension were not significantly different between BR-treated and control seedlings. In pressure-block experiments, the initial rate of relaxation was 2-fold faster in BR-treated plants as compared with controls, whereas after 125 min the total amount of relaxation and the relaxation rate were the same for the two treatments. Osmotic pressure of cell sap expressed from this 3-mm region showed a large decrease (28%) in BR-treated seedlings compared to the controls. We conclude that BR stimulates growth in pakchoi by accelerating the biochemical processes that cause wall relaxation, without inducing a large change in wall mechanical properties.

9.
FEBS Lett ; 436(1): 92-8, 1998 Sep 25.
Artículo en Inglés | MEDLINE | ID: mdl-9771900

RESUMEN

The aim of this study was to investigate the distribution of a calcium-inhibitable adenylyl cyclase type VI (type VI AC) in the central nervous system using an antiserum directed against the N-terminus of type VI AC. Our results indicate that type VI AC immunoreactivity is generally expressed in many brain regions with different levels of intensity. Most interestingly, the majority of the detected type VI AC immunoreactivity is present in cells of neuronal phenotype. Double immunostaining of type VI AC and markers of various neurotransmitter systems suggest that type VI AC might participate in regulation of the classical neurotransmitter systems and therefore appeared to play a very important role in the central nervous system.


Asunto(s)
Adenilil Ciclasas/metabolismo , Sistema Nervioso Central/enzimología , Neuronas/enzimología , Neurotransmisores/metabolismo , Adenilil Ciclasas/genética , Adenilil Ciclasas/inmunología , Animales , Encéfalo/enzimología , Calcio/metabolismo , Calcio/farmacología , Sueros Inmunes , Inmunohistoquímica/métodos , Proteínas Asociadas a Microtúbulos/metabolismo , Reacción en Cadena de la Polimerasa , Conejos , Ratas , Proteínas Recombinantes/genética , Proteínas Recombinantes/inmunología , Proteínas Recombinantes/metabolismo , Transcripción Genética , Tirosina 3-Monooxigenasa/metabolismo
10.
Environ Health Perspect ; 109(10): 1011-7, 2001 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-11675266

RESUMEN

Arsenic is a notorious environmental toxicant known as both a carcinogen and an atherogen in human beings, but the pathogenic mechanisms are not completely understood. In cell culture studies, trivalent arsenic enhanced oxidative stress in a variety of mammalian cells, and this association may be closely associated with the development of arsenic-related diseases. To investigate the effect of arsenic exposure on oxidative stress in humans, we conducted a population study to determine the relationships of blood arsenic to reactive oxidants and antioxidant capacity at the individual level. We recruited 64 study subjects ages 42-75 years from residents of the Lanyang Basin on the northeast coast of Taiwan, where arsenic content in well water varies from 0 to > or = 3,000 microg/L. We used a chemiluminescence method, with lucigenin as an amplifier for measuring superoxide, to measure the plasma level of reactive oxidants. We used the azino-diethyl-benzthiazoline sulphate method to determine the antioxidant capacity level in plasma of each study subject. We determined arsenic concentration in whole blood by hydride formation with an atomic absorption spectrophotometer. The average arsenic concentration in whole blood of study subjects was 9.60 +/- 9.96 microg/L (+/- SD) with a range from 0 to 46.50 microg/L. The level of arsenic concentration in whole blood of study subjects showed a positive association with the level of reactive oxidants in plasma (r = +0.41, p = 0.001) and an inverse relationship with the level of plasma antioxidant capacity (r = -0.30, p = 0.014). However, we found no significant association (p = 0.266) between levels of plasma reactive oxidants and antioxidant capacity. Our results also show that the lower the primary arsenic methylation capability, the lower the level of plasma antioxidant capacity (p = 0.029). These results suggest that ingestion of arsenic-contaminated well water may cause deleterious effects by increasing the level of reactive oxidants and decreasing the level of antioxidant capacity in plasma of individuals. Persistent oxidative stress in peripheral blood may be a mechanism underlying the carcinogenesis and atherosclerosis induced by long-term arsenic exposure.


Asunto(s)
Antioxidantes/farmacología , Arsénico/efectos adversos , Arsénico/sangre , Contaminantes Ambientales/efectos adversos , Contaminantes Ambientales/sangre , Estrés Oxidativo , Especies Reactivas de Oxígeno/sangre , Adulto , Anciano , Arteriosclerosis/fisiopatología , Femenino , Humanos , Masculino , Metilación , Persona de Mediana Edad , Neoplasias/fisiopatología , Taiwán
11.
Ann Clin Biochem ; 25 ( Pt 6): 661-7, 1988 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-3254106

RESUMEN

A direct injection HPLC method for the sumultaneous measurement of serum paracetamol and salicylate is described using a Pinkerton internal surface reversed-phase column with benzoic acid as internal standard. The method is linear to at least 1000 mg/L for both drugs and shows good precision at levels of 62-500 mg/L. None of the drugs tested for interference affected the quantitation of either drug. In patient samples, the values obtained with this method correlated well with those from enzymatic paracetamol and Trinder salicylate methods.


Asunto(s)
Acetaminofén/sangre , Salicilatos/sangre , Acetaminofén/normas , Benzoatos , Ácido Benzoico , Cromatografía Líquida de Alta Presión/métodos , Humanos , Estándares de Referencia , Salicilatos/normas
12.
Ann Clin Biochem ; 33 ( Pt 2): 112-8, 1996 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-8729718

RESUMEN

The short Synacthen (tetracosactrin) test (SST) is an established method of assessing adrenocortical reserve, and is increasingly replacing the insulin tolerance test (ITT) for the assessment of the hypothalamic-pituitary-adrenal (HPA) axis. However, there is no consensus on how the test is performed, and various time points and routes of administration are used. The present study was done, first, to determine whether there was any difference in cortisol responses when Synacthen was administered intramuscularly compared with intravenously and, secondly, to compare cortisol responses at 30 and 60 min. We found no significant difference between the two routes of administration. However, cortisol responses at 60 min were significantly higher than at 30 min (P < 0.05). Previous validations for the use of the SST in place of the ITT have used cortisol responses 30 min after Synacthen. We conclude that where the SST is used to assess the HPA axis, cortisol response at 30 min after intravenous Synacthen should be used.


Asunto(s)
Cosintropina , Hipopituitarismo/diagnóstico , Sistema Hipotálamo-Hipofisario/fisiopatología , Sistema Hipófiso-Suprarrenal/fisiopatología , Adulto , Anciano , Análisis de Varianza , Femenino , Humanos , Sistema Hipotálamo-Hipofisario/metabolismo , Insulina , Modelos Lineales , Masculino , Persona de Mediana Edad , Tasa de Secreción
13.
Bioresour Technol ; 76(2): 131-5, 2001 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-11131796

RESUMEN

The Erh-Ren River is one of the most polluted rivers in Taiwan. Although its flow rate is relatively low, the rate is still beyond the capacity of any traditional water treatment facility. A pilot-scale constructed wetland (CW) is the attempt used to purify the highly polluted river water and to collect data for the construction and operation of a full-scale system in the future. This article reports the results from this initial stage of our research work. During the study, the most efficient nutrient removal occurred between April and October. The monthly average removal rates of chemical oxygen demand (COD) ranged from 13-51% of ammonia-N (AN) from 78-100%, and of orthophosphate (OP) from 52-85%. After November, input COD levels increased, and the monthly average removal rates of ammonia-N dropped to 16% and of orthophosphate to 13%. The dramatic changes in removal efficiency suggest that the macrophytes in the CW had a direct influence on the water treatment and that the change of seasons and the quality of the river water inhibited the growth of the macrophytes.


Asunto(s)
Contaminantes Químicos del Agua/metabolismo , Amoníaco/metabolismo , Biodegradación Ambiental , Ecosistema , Agua Dulce , Organofosfatos/metabolismo , Consumo de Oxígeno , Proyectos Piloto , Taiwán
14.
Fam Med ; 32(5): 338-41, 2000 May.
Artículo en Inglés | MEDLINE | ID: mdl-10820676

RESUMEN

BACKGROUND: Streptococcus pneumoniae is the cause of significant preventable morbidity and mortality each year, especially among the elderly. This study evaluated the effectiveness of a three-step strategy to improve pneumococcal vaccination rates in patients ages 65 and older. METHODS: We obtained a baseline vaccination rate by chart review of a randomized list of patients ages 65 and older. Interventions that included physician education, a system of office prompts, and patient education were instituted for 1 year. We performed a second chart review to determine the success of the intervention. RESULTS: Vaccination rates increased significantly from 56.7% to 75.8%. No significant difference in initial vaccination rates between men and women was found. Although rates improved for both men and women, only the increase in vaccination for men was significant. CONCLUSIONS: This study shows that an easy and inexpensive intervention can substantially impact pneumococcal vaccination rates. Specifically, a three-step approach that combines provider education, office prompts, and patient education has proven effective.


Asunto(s)
Vacunas Bacterianas/administración & dosificación , Programas de Inmunización/métodos , Infecciones Neumocócicas/prevención & control , Adolescente , Adulto , Anciano , Niño , Preescolar , Femenino , Humanos , Programas de Inmunización/normas , Masculino , Persona de Mediana Edad , Guías de Práctica Clínica como Asunto
16.
Phys Sportsmed ; 26(8): 31-6, 1998 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-20086840

RESUMEN

Osteochondritis dissecans (OCD) should be considered in young, active patients who have generalized or anterior knee pain. A careful physical exam includes a Wilson test, thigh girth measurements, diagnostic tunnel view radiographs, and other imaging studies as needed for grading and prognosis. Two case reports demonstrate the signs and symptoms of OCD. Treatment by primary care physicians with sports medicine training may be conservative if lesions are medial and in situ and if patients are not skeletally mature; otherwise, referral is advised. Prompt surgical treatment is generally successful.

19.
Plant Physiol ; 109(2): 627-36, 1995 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-7480351

RESUMEN

Two Pelargonium 1-aminocyclopropane-1-carboxylate (ACC) synthase cDNAs (GAC-1 and GAC-2) were identified and characterized. GAC-1 is 1934 bp long with a 1446-bp open reading frame encoding a 54.1-kD polypeptide. GAC-2 is a 1170-bp-long ACC synthase polymerase chain reaction fragment encoding 390 amino acids. Expression of GAC-1 and GAC-2 together with a previously identified ACC oxidase (GEFE-1) was examined in different Pelargonium plant parts, and leaves were subjected to osmotic stress (sorbitol), metal ion stress (CuCl2), auxin (2,4-dichlorophenoxyacetic acid [2,4-D]), and ethylene. GAC-1 expression was not detectable in any of the plant parts tested, whereas high levels of GAC-2 were expressed in the leaf bud, young leaf, young floret, fully open floret, and senescing floret. GAC-2 was expressed to a lesser degree in fully expanded leaves or roots and was undetectable in old leaves and floret buds. GEFE-1 was detectable at all leaf ages tested, in young and fully open florets, and in the roots; however, the highest degree of expression was in the senescing florets. GAC-1 was induced by sorbitol. Both GAC-1 and GAC-2 were only slightly affected by CuCl2 and induced indirectly by 2,4-D. GEFE-1 was highly induced by sorbitol, CuCl2, and 2,4-D. GAC-1, GAC-2, and GEFE-1 were unaffected by ethylene treatment. These results suggest that GAC-1 is only induced by stress and that GAC-2 may be developmentally regulated, whereas GEFE-1 is influenced by both stress and development.


Asunto(s)
ADN Complementario/química , Isoenzimas/biosíntesis , Liasas/biosíntesis , Plantas/enzimología , Secuencia de Aminoácidos , Secuencia de Bases , Southern Blotting , Cobre/farmacología , ADN Complementario/aislamiento & purificación , Etilenos/metabolismo , Etilenos/farmacología , Regulación Enzimológica de la Expresión Génica/efectos de los fármacos , Regulación Enzimológica de la Expresión Génica/fisiología , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Regulación de la Expresión Génica de las Plantas/fisiología , Ácidos Indolacéticos/farmacología , Isoenzimas/química , Isoenzimas/aislamiento & purificación , Liasas/química , Liasas/aislamiento & purificación , Datos de Secuencia Molecular , Sistemas de Lectura Abierta , Desarrollo de la Planta , Hojas de la Planta , Plantas/genética , Proteínas Recombinantes/biosíntesis , Proteínas Recombinantes/química , Proteínas Recombinantes/aislamiento & purificación , Sorbitol/farmacología
20.
Plant Physiol ; 98(1): 97-100, 1992 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-16668654

RESUMEN

Low O(2) conditions were obtained by flowing N(2) through the solution in which the tomato plants (Lycopersicon esculentum Mill cv Heinz 1350) were growing. Time course experiments revealed that low O(2) treatments stimulated 1-aminocyclopropane-1-carboxylate (ACC) synthase production in the roots and leaves. After the initiation of low O(2) conditions, ACC synthase activity and ACC content in the roots increased and reached a peak after 12 and 20 hours, respectively. The conversion of ACC to ethylene in the roots was inhibited by low levels of O(2), and ACC was apparently transported to the leaves where it was converted to ethylene. ACC synthase activity in the leaves was also stimulated by low O(2) treatment to the roots, reaching a peak after 24 hours. ACC synthase levels were enhanced by cobalt chloride and aminooxyacetic acid (AOA), although they inhibited ethylene production. Cobalt chloride enhanced ACC synthase only in combination with low O(2) conditions in the roots. Under aeration, AOA stimulated ACC synthase activity in both the roots and leaves. However, in combination with low O(2) conditions, AOA caused a stimulation in ACC synthase activity in the leaves and no effect in the roots.

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