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1.
Physiol Plant ; 175(4): e13958, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37338179

RESUMEN

There is generally a trade-off in the resistance to drought and to waterlogging. However, several species are sequentially subjected to both stressors in many environments. We evaluated the ecophysiological strategies to cope with multiple sequential stress of waterlogging and drought (W + D) of three taxa differing in stress resistance and root morphology: the phreatophic Eucalyptus camaldulensis (Ec) and two shallow-rooted willow clones: Salix matsudana x Salix alba (SmxSa) and Salix nigra (Sn4). Individuals of the three taxa were grown in pots and assigned to either of four treatments: Control (well-watered plants), well-watered followed by drought (C + D); waterlogged for 15 days followed by drought (W15d + D) and waterlogged for 30 days followed by drought (W30d + D). Biomass allocation, growth (diameter, height, length of leaves, and roots), specific leaf area, stomatal conductance, water potential, hydraulic conductivity of roots and branches, leaf C13 and root cortical aerenchyma formation were determined at different stages of the experiment. Ec growth was not affected by W + D, developing tolerance strategies at leaf and whole plant levels. Differential effects of W + D were observed in both Salix clones depending on the time of waterlogging. In Sn4 and SmxSa, the root biomass was affected in W15d + D treatment, but a root tolerance response (aerenchyma and adventitious root formation) was observed in W30d + D. In the three taxa, and contrary to expectations, the previous exposure to a waterlogging period did not increase the susceptibility of the plants to a subsequent drought event. On the contrary, we found tolerance, which depended on the time of waterlogging exposure.


Asunto(s)
Sequías , Eucalyptus , Agua/fisiología , Hojas de la Planta/fisiología , Madera , Eucalyptus/genética , Estrés Fisiológico , Raíces de Plantas
2.
Perspect Public Health ; 143(1): 22-28, 2023 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-34130548

RESUMEN

AIMS: Cervical cancer incidence and mortality rates are approximately 55% higher in the Rio Grande Valley (RGV) along the Texas-Mexico border compared with the average rates in the US. Our aim was to improve cervical cancer prevention efforts in the RGV through a comprehensive multilevel intervention initiative focused on community education, patient navigation, and training of local providers. METHODS: We initiated a program in the RGV which consisted of (1) community education, (2) patient navigation, and (3) a training/mentoring program for local medical providers including hands-on training courses coupled with telementoring using Project ECHO® (Extension for Community Health Outcomes). We assessed the number of women undergoing cervical cancer screening, diagnosis, and treatment at three participating clinics caring for underserved women in the region. RESULTS: From November 2014 to October 2018, 14,846 women underwent cervical cancer screening. A total of 2030 (13.7%) women underwent colposcopy for abnormal results (179% increase over baseline) and 453 women underwent loop electrosurgical excision procedures (LEEPs) for treatment of cervical dysplasia. Invasive cancer was diagnosed in 39 women who were navigated to a gynecologic oncologist for treatment. Seven local medical providers were trained to perform colposcopy and/or LEEP. Project ECHO telementoring videoconferences were held every 2 weeks for a total 101 sessions with an average of 22 participants per session and a total of 180 patient cases presented and discussed. CONCLUSIONS: Our program led to a large number of women undergoing diagnosis and treatment of cervical dysplasia in the RGV. If sustained, we anticipate these efforts will decrease cervical cancer rates in the region. The program is currently being expanded to additional underserved areas of Texas and globally to low- and middle-income countries.


Asunto(s)
Navegación de Pacientes , Displasia del Cuello del Útero , Neoplasias del Cuello Uterino , Femenino , Humanos , Masculino , Neoplasias del Cuello Uterino/diagnóstico , Neoplasias del Cuello Uterino/prevención & control , Texas/epidemiología , México/epidemiología , Detección Precoz del Cáncer
3.
Ethn Health ; 26(2): 206-224, 2021 02.
Artículo en Inglés | MEDLINE | ID: mdl-29998738

RESUMEN

Background: Gendered perspectives may be particularly important in shaping norms and values around HPV and HPV vaccination, as previous research suggests that sexuality taboos (e.g. promiscuity) may contribute to low perceived risk among adolescent and young adult Hispanic females. However, research to date focuses primarily on Hispanic mothers, adolescent females, and women of HPV vaccine-eligible age. Hispanic father's perspectives are relatively unknown despite father's important role in shaping norms for their female children.Objective: To close this gap, this study examines gendered perspectives in knowledge, beliefs, and attitudes about HPV and HPV vaccination from Hispanic parents (mothers and fathers), women of vaccine-eligible age (18-26 years old), and women eligible for Pap Test screening (>26 years old) living in two counties along the Texas-Mexico border.Design: We conducted eight focus groups. Research staff transcribed audio recordings verbatim and uploaded them into Atlas(ti) 5.0 for analysis. The research team analyzed the data for content, meaning, patterns and themes using the constant comparison approach.Results: Perspectives were highly gendered. Women's (all groups combined) beliefs focused on misconceptions around how the HPV virus is contracted (e.g. toilet surfaces). Women also linked HPV-related sexual risk to adultery and indiscretion of male partners. Fathers (men) were more likely to link risk to female promiscuity. Fathers also worried that HPV vaccination might increase promiscuity. All groups believe that HPV vaccination is a way to protect Hispanic females in the face of beliefs around sexual behavior and risk of contracting HPV.Conclusion: Results suggest gendered differences in risk beliefs concerning HPV among Hispanics living along the Texas-Mexico border. Researchers can use these findings to address barriers to HPV vaccination, as well as to create culturally appropriate prevention messages that may help reduce disparities in HPV among Hispanic women.


Asunto(s)
Alphapapillomavirus , Infecciones por Papillomavirus , Vacunas contra Papillomavirus , Neoplasias del Cuello Uterino , Adolescente , Adulto , Niño , Femenino , Conocimientos, Actitudes y Práctica en Salud , Humanos , Masculino , Americanos Mexicanos , Papillomaviridae , Infecciones por Papillomavirus/prevención & control , Aceptación de la Atención de Salud , Tabú , Vacunación , Adulto Joven
4.
Sci Rep ; 10(1): 18152, 2020 10 23.
Artículo en Inglés | MEDLINE | ID: mdl-33097768

RESUMEN

Environmental challenges are integrated in the inmunoneuroendocrine interplay, impacting the immune system of the challenged individuals, and potentially implying transgenerational effects on their offspring. This study addressed whether dietary supplementation with thymol can modulate the immune response of adult Japanese quail when simultaneously exposed to an inoculum of inactivated Salmonella Enteritidis and a chronic heat stress (CHS). We also evaluated whether the experienced situations by adults can affect the immune response of their undisturbed offspring. In the parental generation, supplemented quail exposed to CHS had a higher inflammatory response and similar values of the heterophil/lymphocyte (H/L) ratio than those that were not supplemented. In their offspring, those chicks whose parents were exposed to CHS showed higher inflammatory response and lower antibody production. Regarding the H/L ratio, chicks whose parents were supplemented showed lower H/L ratio values. Dietary supplementation with thymol partially and positively modulated the inflammatory response and avoided H/L ratio alteration in the parental generation exposed to high environmental temperatures, suggesting these adults were better at dealing with the challenge. The lower H/L ratio values in the offspring suggests that chicks are more capable to deal with potential stressful situations associated with conventional breeding conditions.


Asunto(s)
Alimentación Animal , Enfermedades de las Aves/prevención & control , Coturnix/inmunología , Trastornos de Estrés por Calor/veterinaria , Salmonella enteritidis/inmunología , Timol/administración & dosificación , Animales , Enfermedades de las Aves/sangre , Enfermedades de las Aves/inmunología , Enfermedades de las Aves/microbiología , Coturnix/microbiología , Femenino , Trastornos de Estrés por Calor/sangre , Trastornos de Estrés por Calor/inmunología , Trastornos de Estrés por Calor/prevención & control , Calor/efectos adversos , Recuento de Linfocitos , Linfocitos/inmunología , Masculino , Exposición Materna , Neuroinmunomodulación/efectos de los fármacos , Óvulo/inmunología , Exposición Paterna , Factores Sexuales
5.
Poult Sci ; 98(2): 1012-1016, 2019 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-30165460

RESUMEN

Consumer concern on the quality of products and animal welfare has greatly increased during the past decades. Dietary synthetic antibiotic products used as growth promoters have been restricted or banned in many countries. Edible plants, essential oils, or their main components were suggested as natural feed supplements to improve growth, products' quality, and welfare-related parameters. Thymol (THY), a main component of oregano essential oil, has been proved as an effective antimicrobial and antioxidant compound. Tocopherol (TOC) evidenced antioxidant activity with potential as a growth promoter and a synergic antioxidant activity between TOC and ascorbyl palmitate (AP) has also been reported. Herein, we evaluated whether broiler diet supplementation with THY, and THY with a formulation mix containing TOC and AP (1:0.5:0.5, respectively) have potential as growth enhancers under commercial conditions. Potential protective effects against foot pad dermatitis and hock burns were also evaluated. Newly hatched male broiler chicks with similar body weight (BW) were randomly assigned to 1 of 7 groups (4 replicates each) as follows: Basal (no feed supplements added), Promotor (Basal + 6.26 µmol flavomycin/kg feed), BHT (Basal + 1.33 mmol of buthylated hidroxytoluene (BHT)/kg feed), Prom-BHT (Basal + 6.26 µmol flavomycin/kg feed + 1.33 mmol of BHT/kg feed), TOC-AP (Basal + 0.67 mmoles of TOC + 0.67 mmoles of AP/kg feed), THY (Basal + 1.33 mmoles of THY/kg feed), and THY-TOC-AP (Basal + 0.67 mmoles of THY + 0.67 mmoles of a mix 1:1 of TOC-AP). Along 7 wk, BW, feed intake, and feed conversion ratio were evaluated. Skin injuries were assessed at 35 d of age. At the end of the study (42 d), compared to Basal group, similarly enhanced final BW were observed in all groups but TOC-AP. No main differences between groups were detected in feed intake, feed conversion ratio, or skin injuries. Findings suggest that THY itself or in combination with TOC-AP may have value as a natural growth enhancer alternative for broilers.


Asunto(s)
Alimentación Animal/análisis , Ácido Ascórbico/análogos & derivados , Pollos , Sustancias de Crecimiento/farmacología , Timol/farmacología , alfa-Tocoferol/farmacología , Animales , Ácido Ascórbico/administración & dosificación , Ácido Ascórbico/farmacología , Dieta/veterinaria , Suplementos Dietéticos/análisis , Enfermedades del Pie/prevención & control , Enfermedades del Pie/veterinaria , Masculino , Enfermedades de las Aves de Corral/prevención & control , Distribución Aleatoria , Timol/administración & dosificación , alfa-Tocoferol/administración & dosificación
6.
Reprod Domest Anim ; 52(5): 911-913, 2017 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-28580618

RESUMEN

Puberty is a stage of sexual development determined by the interaction of environmental factors and genetic mechanisms. Among them, thyroid function plays a key role in sexual development and spermatogenic function and is under the control of several genes, including the well-described thyroglobulin gene (TG). Previous reports have shown genetic association between thyroid function and selected single nucleotide polymorphisms (SNPs) in taurine cattle. Therefore, the identification of genetic mechanisms involved in the regulation of this trait can assist with the selection for early pubertal bulls, thus improving genetic progress in livestock breeding. The aim of this study was to validate the association between TG SNPs and age at puberty in zebuine bulls. Three SNPs (rs110406764, rs109662686, rs109057985) were genotyped in 159 Guzerat animals using SEQUENOM technology. Results showed a significant association (p < .05) between the studied SNPs and puberty age, in agreement with our previous reports in a taurine breed. Interestingly, allele frequencies were different from those already reported, being GAT the most favourable allele for age at puberty in Guzerat (94.4 days lower). Overall, our findings corroborate previous reports and reinforce the importance of genetic influence in the regulation of sexual development and puberty through a thyroid pathway in zebuine cattle.


Asunto(s)
Bovinos/genética , Maduración Sexual/genética , Tiroglobulina/genética , Animales , Cruzamiento , Masculino , Polimorfismo de Nucleótido Simple , Escroto/anatomía & histología , Espermatogénesis
7.
Rev. argent. radiol ; 79(4): 209-213, dic. 2015. ilus
Artículo en Español | LILACS | ID: biblio-843194

RESUMEN

La embolia grasa (EG) es una obstrucción de los vasos sanguíneos por glóbulos de grasa. Ha sido descrita en la circulación pulmonar con una gran variedad de asociaciones, pero las más comunes e importantes se dan con fracturas de huesos largos y daño de tejido blando debido a traumatismo grave. Por su parte, el síndrome de embolia grasa (SEG) es una manifestación poco frecuente, aunque grave, del fenómeno de embolia grasa, que se caracteriza clínicamente por la tríada disnea, petequias y confusión mental. La razón de la discrepancia entre la presencia de embolia grasa y el desarrollo del síndrome no es clara. Presentamos el caso de un hombre de 41 años que, inmediatamente después del trauma, presentó en la tomografía computada (TC) inicial defectos de llenado de atenuación grasa dentro de las arterias pulmonares. Estos fueron interpretados como múltiples embolias grasas macroscópicas. Los valores de atenuación de la tomografía computada multidetector (TCMD) de las embolias pulmonares deben examinarse cuidadosamente en el contexto de un traumatismo agudo o después de procedimientos ortopédicos, debido a la complicación rara pero potencialmente fatal del SEG. En los centros de trauma, la TCMD es una herramienta esencial para hacer el diagnóstico de la embolia grasa macroscópica, así como también para descartar otras causas de hipoxia, como la embolia pulmonar trombótica. La reconstrucción de cortes finos debe utilizarse para la evaluación detallada de la vasculatura pulmonar.


Fat embolism (FE) may be defined as the blockage of blood vessels by fat globules. Pulmonary fat embolisms are reported to be associated with a wide variety of conditions, with the most common and important ones being with long bone fractures and soft tissue damage due to severe trauma. Fat embolism syndrome (FES) is a rare but serious manifestation of the fat embolism phenomenon, characterized clinically by a triad of dyspnea, petechiae, and mental confusión. The discrepancy between the presence of a fat embolism and the development of fat embolism syndrome is unclear. The case is presented of a 41 year-old mate who, on the initial trauma CT sean, presented with filling defeets of fat attenuation within the pulmonary arteries. Those were interpreted as múltiple macroscopic fat emboli. The CT attenuation valúes of pulmonary embolism should be carefully examined in the setting of acute trauma or after orthopedic procedures, as the rare but potentially fatal complicaron of FES may result. In trauma centers, multidetectorcomputed tomography is an essential tool to make the diagnosis of macroscopic fat embolism, and to exelude other causes of hypoxia, such as thrombotic pulmonary embolism. These reconstructions should be used for detailed evaluation of the pulmonary vasculature.


Asunto(s)
Humanos , Masculino , Adulto , Embolia Pulmonar/diagnóstico por imagen , Embolia Grasa/diagnóstico por imagen , Embolia Pulmonar/epidemiología , Radiografía Abdominal , Radiografía Torácica , Tomografía Computarizada por Rayos X , Cerebro/diagnóstico por imagen , Angiografía por Tomografía Computarizada
9.
Meat Sci ; 108: 17-20, 2015 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-26010991

RESUMEN

The biochemical bases of meat color are determined by the concentration and redox state of myoglobin, hemoglobin, cytochromes, and other pigments. Post-mortem depletion of cellular oxygen results in oxidative stresses that consume NADH and affects reducing activity, while enzymatic detoxification influences the cellular oxidative processes, both affecting meat color. The aim of this work was to study the influence of several genes related to cellular oxidative processes that could affect CIELAB meat color parameters. The study was performed in steers that received a grass-based diet combined with grain, hays and silages. Results suggest a possible link between colorimetric parameters (a*, b* and chroma) and SNPs in the GSTP1 gene (P<0.05). Although the influence of the enzymes, encoded by GSTP1 gene, on meat color has been proposed previously at biochemical level and protein expression level, further association studies in different populations and functional studies of proteins are needed to confirm the genetic determination of that gene on meat color.


Asunto(s)
Bovinos/genética , Color , Oxidación-Reducción , Carne Roja , Alimentación Animal , Animales , Dieta/veterinaria , Glutatión Peroxidasa/genética , Glutatión Peroxidasa/metabolismo , Gutatión-S-Transferasa pi/genética , Gutatión-S-Transferasa pi/metabolismo , Isoenzimas/genética , Isoenzimas/metabolismo , L-Lactato Deshidrogenasa/genética , L-Lactato Deshidrogenasa/metabolismo , Lactato Deshidrogenasa 5 , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo , Músculo Esquelético/metabolismo , Mioglobina/metabolismo , Fosfolípido Hidroperóxido Glutatión Peroxidasa , Polimorfismo de Nucleótido Simple
10.
Bioresour Technol ; 106: 55-62, 2012 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-22197337

RESUMEN

A simple alkaline pre-treatment of Cupressus sempervirens cone chips was performed to improve their biosorption capacity towards methylene blue and rhodamine B from aqueous solutions, in batch and continuous modes. Biosorption kinetics were determined from single and binary dyes solutions, and properly described by the pseudo-second-order rate model. Experimental single-dye equilibrium isotherms fitted the Langmuir-Freundlich model, with maximum biosorption capacities of 0.68mmol/g for methylene blue and 0.50mmol/g for rhodamine B. Single-dye dynamic biosorption showed that breakthrough time for methylene blue biosorption was almost four times longer than for rhodamine B and that the alkaline modification of the chips greatly improved the biosorption performance. Competitive dynamic biosorption demonstrated the preference of the modified cone chips for biosorbing methylene blue, confirmed by the exit concentration overshoots obtained in the breakthrough curves of rhodamine B.


Asunto(s)
Técnicas de Cultivo Celular por Lotes/métodos , Colorantes/aislamiento & purificación , Cupressus/química , Hidróxidos/farmacología , Compuestos de Potasio/farmacología , Residuos/análisis , Contaminantes Químicos del Agua/aislamiento & purificación , Adsorción/efectos de los fármacos , Biodegradación Ambiental/efectos de los fármacos , Cupressus/efectos de los fármacos , Concentración de Iones de Hidrógeno/efectos de los fármacos , Cinética , Azul de Metileno/aislamiento & purificación , Modelos Químicos , Rodaminas/aislamiento & purificación , Soluciones , Temperatura
11.
Artículo en Español | MEDLINE | ID: mdl-23751785

RESUMEN

INTRODUCTION: Insomnia is a sleep disorder characterized by a deficient or poor quality sleep, with adverse daytime consequences. Prevalence is 30-50% in adults and can be associated with depression or lead to the development of this condition. Despite the high prevalence rates, is a unrecognized, misdiagnosis and undertreated. There is not much publications about its prevalence in patients with chronic diseases. OBJECTIVES: to determine prevalence and clinical characteristics of insomnia in outpatients with chronic diseases. MATERIALS AND METHODS: Prospective observational cross-sectional descriptive study. Insomnia was defined based on ICSD-2criteria. The data collection was performed by a questionnaire. RESULTS: We surveyed 100 patients who attended the consultation of various clinical specialties, mean age 50 years old, 57% were women. Sixty nine per cent of them met criteria for insomnia. The most prevalent diseases were hypertension: 57%, asthma 20%, diabetes: 18% and hypothyroidism: 17%. Among patients with insomnia, 62% were women, 35% had insomnia without another illness, and the remaining 65% had secondary conditions associated with insomnia (60% depression). 25% of patients consulting for insomnia ever. The prevalence of criteria for depression in outpatients with chronic diseases was 52%, amounting to 63% in patients suffering from insomnia. DISCUSSION: The prevalence of insomnia in patients with chronic diseases is high (in outpatients with chronic disease: 69%), higher than the average rate described in the general population. It is an undertreated condition. CONCLUSIONS: The prevalence of insomnia in patients with chronic diseases is high, it is underdiagnosed and undertreated. It is associated with depression in high rate.


Introducción: Insomnio es el trastorno caracterizado por sueño deficiente o de mala calidad con consecuencias diurnas adversas. La prevalencia es 30-50% en adultos y puede llevar al desarrollo de depresión. A pesar de las altas tasas de prevalencia es una entidad poco reconocida, subdiagnosticada y subtratada. Poco se ha publicado acerca de la prevalencia en pacientes con enfermedades crónicas. Objetivos: conocer prevalencia y características clínicas del insomnio en pacientes ambulatorios con enfermedades crónicas. Materiales y métodos: Estudio prospectivo descriptivo observacional de corte transversal. Se definió insomnio en base a los criterios del ICSD-2. La obtención de los datos se realizó por un cuestionario autoadministrado. Resultados: Encuestamos a 100 pacientes que acudieron a la consulta de diferentes especialidades clínicas, edad promedio 50 años. El 57% mujeres. El 69% cumplía criterios de insomnio. Las enfermedades más prevalente fueron HTA: 57%; asma: 20%, diabetes: 18% e hipotiroidismo: 17%. Entre los pacientes con insomnio, el 62% fueron mujeres, el 35 % lo presentaban de manera aislada y el restante 65% presentaba condiciones asociadas a insomnio secundario (el 60% presentaban depresión). La cuarta parte de los pacientes consultó por insomnio alguna vez. La prevalencia de criterios de depresión en los enfermos crónicos analizados fue de 52%, y asciende a 63% en los pacientes que padecen insomnio. Discusión: La prevalencia de insomnio en pacientes con enfermedades crónicas es alta, siendo en pacientes ambulatorios con enfermedades crónicas del 69%, muy superior a la media descripta en la población general. Es una entidad subtratada. Conclusiones: La prevalencia de insomnio en pacientes con enfermedades crónicas es alta, está subdiagnosticada y subtratada. Presenta una asociación significativa con depresión.


Asunto(s)
Enfermedad Crónica/epidemiología , Trastornos del Inicio y del Mantenimiento del Sueño/epidemiología , Adulto , Anciano , Anciano de 80 o más Años , Argentina/epidemiología , Asma/epidemiología , Distribución de Chi-Cuadrado , Comorbilidad , Estudios Transversales , Depresión/epidemiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Prevalencia , Estudios Prospectivos , Adulto Joven
12.
Bioresour Technol ; 101(24): 9500-7, 2010 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-20727738

RESUMEN

The feasibility of using cypress cone chips from Cupressus sempervirens as a low-cost biosorbent for the removal of two representative basic dyes, methylene blue (MB) and rhodamine B (RhB), from aqueous solutions was investigated in batch and continuous modes. Dyes biosorption was strongly dependent on the solution's pH. Sorption kinetics was determined and properly described by the pseudo-second-order rate model. Experimental equilibrium isotherms fitted the Langmuir model, showing maximum biosorption capacities of 0.62 mmol/g for MB and 0.24 mmol/g for RhB. Competitive experiments from a binary solution of the dyes demonstrated the preference of the cone chips for biosorbing MB. Very low desorption efficiencies were obtained for both dyes. Dynamic experiments showed that the breakthrough time was three times higher for MB biosorption than for RhB for the same conditions. Breakthrough curves were properly represented by a mathematical model.


Asunto(s)
Colorantes/aislamiento & purificación , Cupressus/anatomía & histología , Cupressus/metabolismo , Purificación del Agua/métodos , Adsorción , Biodegradación Ambiental , Concentración de Iones de Hidrógeno , Cinética , Azul de Metileno/aislamiento & purificación , Modelos Químicos , Rodaminas/aislamiento & purificación , Soluciones , Temperatura
13.
Acta Crystallogr B ; 59(Pt 2): 175-81, 2003 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-12657811

RESUMEN

Some experimental results have indicated that hydroxyapatite (HA) and octacalcium phosphate (OCP) can form an epitaxic interface. Subsequently the OCP-HA interface has become of great biological interest in the context of mineralized tissue formation. In this work a new OCP-HA interface model based on Brown's proposed configuration [Brown (1962), Nature, 197, 1048-1050] and using the minimum interface free-energy optimization is presented. This new model is formed by half a unit cell of HA and one unit cell of OCP, as in Brown's model, but in our case [1-210] of HA is 'glued' with [010] of OCP. Therefore, the relationship found was: [000-1](HA) parallel to [001](OCP) and [1-210](HA) parallel to [010](OCP). Self-consistent field methods were used for the analysis of Brown's model and ours. It is shown that the atoms in our model have similar environments as in the HA and OCP unit cells and that, as a result of the differences between HA and OCP unit-cell parameters, this interface presents misfit-dislocation-like features. High-resolution transmission electron microscopy (HREM) simulated images for the new interface model have been included and, when they are compared with the experimental ones, the similarity is quite good.

14.
J Enzyme Inhib ; 15(2): 171-83, 2000.
Artículo en Inglés | MEDLINE | ID: mdl-10938542

RESUMEN

The major peroxidase from 15-day-old wheat plants was purified to homogeneity by FPLC ion exchange and molecular exclusion chromatography. It consists of a single polypeptide of M(r) 37,500 according to gel filtration and SDS-PAGE and has a pI of 7.0. Kinetics of pyrogallol peroxidation showed that the enzyme follows the accepted mechanism for peroxidase, with kinetic constants k(1) =4.4x10(6) M(-1) s(-1) and k(3) =8.6x10(5) M(-1) s(-1). The effect of different metal ions was assayed on peroxidase activity. None of the ions used had any effect on enzyme activity, except for Cd(II), which was an inhibitor. This was an unexpected and novel finding for a peroxidase. The kinetics of pyrogallol peroxidation at different concentrations of Cd(II) have been studied and a mechanism for Cd(II) inhibition proposed. The results obtained could explain, in part, cadmium-induced oxidative stress.


Asunto(s)
Cadmio/metabolismo , Peroxidasas/antagonistas & inhibidores , Triticum/enzimología , Cinética , Peroxidasas/aislamiento & purificación , Peroxidasas/metabolismo , Pirogalol
15.
Arch Biochem Biophys ; 357(1): 22-6, 1998 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-9721179

RESUMEN

Oxidized states of wheat germ peroxidase isozyme C2 (WGP C2) were investigated by means of electronic absorption spectroscopy. Addition of one molar equivalent of H2O2 to ferric WGP C2 led to the formation of an oxidized species with an absorption spectrum very similar to that of peroxidase compound II, with a Soret maximum at 411 nm and visible maxima at 523 and 553 nm. The transformation took place with an isosbestic point at 409 nm. Stopped flow spectroscopy showed no inflection points for the formation of this species when it was registered at 420 nm, and we could verify the persistence of the isosbestic point from 20 ms to 10 s. The oxidized species decays spontaneously to ferric enzyme in a double-exponential manner. By adding excess H2O2 to the system we obtained an inactive derivative identical to horseradish peroxidase P-670. In the presence of one equivalent of reducing substrate and excess H2O2 compound III was formed. The results so indicate that the species obtained in the reaction of WGP C2 with equimolecular amounts of H2O2 is compound I. The resulting compound I spectrum was identical to that of cytochrome c peroxidase, suggesting the formation of a protein radical rather than the typical pi cation radical, a feature which had not been described before for a plant peroxidase.


Asunto(s)
Peroxidasas/química , Activación Enzimática , Peróxido de Hidrógeno/farmacología , Isoenzimas/química , Estructura Molecular , Oxidación-Reducción/efectos de los fármacos , Semillas/enzimología , Espectrofotometría/métodos , Relación Estructura-Actividad , Triticum/enzimología
16.
Arch Biochem Biophys ; 333(1): 59-65, 1996 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-8806754

RESUMEN

Peroxidation of substrates such as ascorbic acid, pyrogallol, or ferulic acid, as well as indole acetic acid oxidation catalyzed by wheat germ peroxidase (WGP)2 C2, were found to be activated by Ca2+. This activation is independent of the stabilizing effect of structural Ca2+ reported for peroxidases. Steady state kinetics of ferulic acid oxidation catalyzed by WGP C2 showed an increase in the rate of compound I formation and of compound II decomposition in the presence of the ion, evidenced as an increase in rate constants k1, from 8.9 x 10(5) to 4.5 x 10(5) M-1 cm-1, and k3, from 4.4 x 10(5) to 1.1 x 10(6) M-1 cm-1. The dissociation constant Kd, for the cyanide derivative of the enzyme showed a marked decrease from 220 to 34 microM in the presence of Ca2+, thus implying an effect of the ion in the H2O2 binding step. In the presence of Ca2+, a conformational change in the protein was revealed by tryptophan fluorescence, providing a basis for the activation mechanism. Other peroxidases such as horseradish peroxidase and WGP C3 were not activated by Ca2+. The results suggest the existence of a physiological mechanism of control of peroxidase isozymes activity mediated by Ca2+.


Asunto(s)
Calcio/metabolismo , Calcio/farmacología , Peroxidasas/metabolismo , Triticum/enzimología , Calcio/análisis , Ácidos Cumáricos/metabolismo , Activación Enzimática/efectos de los fármacos , Peroxidasa de Rábano Silvestre/metabolismo , Isoenzimas/química , Isoenzimas/metabolismo , Cinética , Oxidación-Reducción , Peroxidasas/química , Espectrometría de Fluorescencia , Triptófano/química
19.
Rev. chil. pediatr ; 55(4): 270-3, 1984.
Artículo en Español | LILACS | ID: lil-22041

RESUMEN

Se presentan 2 lactantes con intoxicacion por vitamina D como consecuencia de un error en la administracion del medicamento por parte de los familiares. El 1er caso recibio 9.000.000 de U en 15 dias a partir del mes de edad. El 2o. caso 4.200.000 en 7 dias a partir de los 17 1/2 meses de vida. Ambos casos fueron clinicamente semejantes. Poliuria, nauseas, vomitos, deshidratacion severa, hipotonia muscular y compromiso del estado general. Se constato hipercalcemia, hipercalciuria y alteracion importante de la capacidad de concentracion renal


Asunto(s)
Lactante , Humanos , Femenino , Intoxicación , Vitamina D , Calcio , Dieta , Prednisona
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