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1.
Animal ; 17 Suppl 5: 100874, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-37394324

RESUMEN

Within poultry production systems, models have provided vital decision support, opportunity analysis, and performance optimization capabilities to nutritionists and producers for decades. In recent years, due to the advancement of digital and sensor technologies, 'Big Data' streams have emerged, optimally positioned to be analyzed by machine-learning (ML) modeling approaches, with strengths in forecasting and prediction. This review explores the evolution of empirical and mechanistic models in poultry production systems, and how these models may interact with new digital tools and technologies. This review will also examine the emergence of ML and Big Data in the poultry production sector, and the emergence of precision feeding and automation of poultry production systems. There are several promising directions for the field, including: (1) application of Big Data analytics (e.g., sensor-based technologies, precision feeding systems) and ML methodologies (e.g., unsupervised and supervised learning algorithms) to feed more precisely to production targets given a 'known' individual animal, and (2) combination and hybridization of data-driven and mechanistic modeling approaches to bridge decision support with improved forecasting capabilities.


Asunto(s)
Macrodatos , Aves de Corral , Animales , Aprendizaje Automático , Algoritmos , Tecnología
2.
Animal ; 15(2): 100089, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33712220

RESUMEN

In general, calf production occurs in less intensive systems. The limitation of nutrients during the gestation phase of beef cows can have negative impacts on the consequent productivity of females. Therefore, this study aimed to evaluate the effects of nutritional levels in the third trimester of pregnancy on the productive performance of beef cows kept in a natural pasture (NP). Eighty-three Charolais × Nelore cows were used, ranging in age from 4 to 12 years, which were divided according to their nutritional levels during the third trimester of pregnancy: NP, cows supplemented with 100% of their energy and protein requirements (SP100) and cows supplemented with 150% of their energy and protein requirements (SP150). The experimental design was completely randomized with three treatments and a varied number of repetitions. The SP100 and SP150 cows presented better body condition at calving (2.92 and 2.99 vs 2.81 points) and at the start of the breeding season (2.90 and 2.95 vs 2.80 points) than did NP cows. The nutritional level of the cows in the third trimester of gestation did not influence the blood metabolite concentrations. The plasma levels of albumin and total proteins were 3.11 and 8.18 g/dl, respectively. Glucose and cholesterol showed values of 74.96 and 166.50 mg/dl. The lowest concentration of blood metabolites was observed in the first postpartum weeks. The SP100 and SP150 cows showed faster follicular growth and, consequently, a higher percentage of females with ovulatory follicles at 21 days postpartum than did NP cows (45.68, 41.11, and 11.00%, respectively). The SP150 cows had a higher pregnancy rate (40.74%), total calf production (295.88 kg/cow), and consequently, offspring sale value. An increased nutritional level in the third trimester of pregnancy improves the postpartum metabolic condition and productive efficiency of beef cows kept on NP.


Asunto(s)
Suplementos Dietéticos , Periodo Posparto , Alimentación Animal/análisis , Fenómenos Fisiológicos Nutricionales de los Animales , Animales , Bovinos , Dieta/veterinaria , Femenino , Lactancia , Embarazo , Índice de Embarazo , Estaciones del Año
3.
Nanotechnology ; 20(6): 065301, 2009 Feb 11.
Artículo en Inglés | MEDLINE | ID: mdl-19417377

RESUMEN

Poly(methyl methacrylate) (PMMA) domains in phase-separated polystyrene-b-poly(methyl methacrylate) (PS-b-PMMA) diblock copolymer thin films were chemically modified for controlled placement of solution synthesized Au nanoparticles having a mean diameter of 24 nm. Colloidal Au nanoparticles functionalized with thioctic acid were immobilized on amine functionalized PMMA domains on the PS-b-PMMA template using 1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride linking chemistry and N-hydroxy sulfosuccinimide stabilizer. Atomic force microscopy and scanning electron microscopy images demonstrated immobilization of Au nanoparticles commensurate with PMMA domains. Nanoparticles form into clusters of single particles, dimers, and linear chains as directed by the PMMA domain size and shape. Capillary forces influence the spacing between Au nanoparticles on PMMA domains. Inter-particle spacings below 3 nm were achieved and these assemblies of closely spaced nanoparticle clusters are expected to exhibit strong localized electromagnetic fields. Thus, these processes and material systems provide an experimental platform for studying resonantly enhanced excitations of surface plasmons as a function of material and geometric structure as well as utilization in catalytic applications.

4.
Science ; 358(6370): 1559-1565, 2017 12 22.
Artículo en Inglés | MEDLINE | ID: mdl-29038373

RESUMEN

Merging neutron stars offer an excellent laboratory for simultaneously studying strong-field gravity and matter in extreme environments. We establish the physical association of an electromagnetic counterpart (EM170817) with gravitational waves (GW170817) detected from merging neutron stars. By synthesizing a panchromatic data set, we demonstrate that merging neutron stars are a long-sought production site forging heavy elements by r-process nucleosynthesis. The weak gamma rays seen in EM170817 are dissimilar to classical short gamma-ray bursts with ultrarelativistic jets. Instead, we suggest that breakout of a wide-angle, mildly relativistic cocoon engulfing the jet explains the low-luminosity gamma rays, the high-luminosity ultraviolet-optical-infrared, and the delayed radio and x-ray emission. We posit that all neutron star mergers may lead to a wide-angle cocoon breakout, sometimes accompanied by a successful jet and sometimes by a choked jet.

5.
Cancer Res ; 44(11): 5092-4, 1984 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-6488169

RESUMEN

The effects of single-dose and fractionated whole-brain irradiation on brain methotrexate (MTX) has been studied in a rat model. The amount of MTX present in the brain 24 hr after a single i.p. dose (100 mg/kg) was the same wether animals were sham irradiated or given a single dose of 2000 rads 6 or 48 hr prior to the drug (6.9, 8.3, and 6.8 pmol MTX/g, wet weight, respectively). Animals sham irradiated or given 2000 rads in 10 fractions over 11 days and treated with an average dose of 1.2 mg MTX/kg i.p. twice a week for 24 weeks did not differ significantly in their brain MTX concentration (7.9 and 8.3 pmol MTX/g, wet weight, respectively). Chronically MTX-treated animals became folate deficient whether they were irradiated or not (450 and 670 pmol folate/g, wet weight, brain in MTX-treated and control animals). Thus, MTX accumulates in the brain with acute or chronic administration, and this accumulation is not altered by this amount of brain irradiation.


Asunto(s)
Encéfalo/efectos de la radiación , Metotrexato/metabolismo , Animales , Encéfalo/metabolismo , Deficiencia de Ácido Fólico/metabolismo , Masculino , Ratas , Ratas Endogámicas , Factores de Tiempo
6.
Gene ; 162(2): 245-8, 1995 Sep 11.
Artículo en Inglés | MEDLINE | ID: mdl-7557437

RESUMEN

We have previously reported the isolation and preliminary characterisation of a full-length cDNA sequence derived from the human BBC1 gene, a gene which displays differential expression in tumours of the female breast [Adams et al., Hum. Mol. Genet. 1 (1992) 91-96]. Here, we report the isolation and characterisation of the Drosophila melanogaster (Dm) homologue of this human gene. The Dmbbc1 cDNA is 62% identical to the human BBC1 cDNA within a conserved open reading frame and the encoded proteins share 74% sequence similarity. The Dmbbc1 mRNA is expressed at all stages of Dm development, with the highest levels of expression occurring during embryogenesis. In addition, the Dm and human BBC1 proteins share remarkable degrees of identity with the products of recently isolated plant and avian bbc1 cDNAs. The sequences of all the predicted BBC1 proteins are highly similar to that of the rat ribosomal subunit protein L13 [Olvera and Wool, Biochem. Biophys. Res. Commun. 201 (1994) 102-107], strongly indicating that the BBC1 protein is ribosomal protein L13.


Asunto(s)
Proteínas de Drosophila , Drosophila melanogaster/embriología , Drosophila melanogaster/genética , Regulación del Desarrollo de la Expresión Génica , Genes de Insecto , Proteínas de Neoplasias/genética , Proteínas Ribosómicas/genética , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Clonación Molecular , ADN Complementario/genética , Femenino , Intrones , Masculino , Datos de Secuencia Molecular , ARN Mensajero/genética , Alineación de Secuencia , Homología de Secuencia de Aminoácido
7.
Invest Ophthalmol Vis Sci ; 42(10): 2217-24, 2001 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-11527933

RESUMEN

PURPOSE: To survey patients with dominant retinitis pigmentosa (RP) for mutations in the RP1 gene to determine the spectrum of dominant mutations in this gene, to estimate the proportion of dominant RP caused by this gene, and to determine whether the clinical features of patients with RP1 mutations differ from features of those with rhodopsin mutations. METHODS: A set of 241 patients who did not have mutations in the rhodopsin gene (based on previous work) formed the basis for the study. Of these patients, 117 had also been previously evaluated and were found not to carry mutations in the RDS gene. The single-strand conformation polymorphism (SSCP) method was used to search for sequence variants, which were then directly sequenced. The relatives of selected patients were recruited for segregation analyses. Clinical evaluations of patients included a measurement of Snellen visual acuity, final dark adaptation thresholds, visual fields, and ERGs. Clinical data were compared with those obtained earlier from a study of 128 patients with dominant rhodopsin mutations. RESULTS: Of the 241 patients, all were screened for the most common RP1 mutation (Arg677Ter), and 10 patients were found to have this mutation. In addition, an evaluation of a subset of 189 patients in whom the entire coding sequence was evaluated revealed the following mutations: Gln679Ter (1 case), Gly723Ter (2 cases), Glu729(1-bp del) (1 case), Leu762(5-bp del) (2 cases), and Asn763(4-bp del) (1 case). All of these mutations cosegregated with RP in the families of the index patients. Nine missense mutations that were each found in six or fewer patients were encountered. The segregation of eight of these was evaluated in the respective patients' families, and only one segregated with dominant RP. This cosegregating missense change was in cis with the nonsense mutation Gln679Ter. Although patients with RP1 mutations had, on average, slightly better visual acuity than patients with rhodopsin mutations, there was no statistically significant difference in final dark-adaptation thresholds, visual field diameters, or cone electroretinogram (ERG) amplitudes. Comparably aged patients with RP1 mutations had visual function that varied by approximately two orders of magnitude, based on visual fields and ERG amplitudes. CONCLUSIONS: Dominant RP1 alleles typically have premature nonsense codons occurring in the last exon of the gene and would be expected to encode mutant proteins that are only approximately one third the size of the wild-type protein, suggesting that a dominant negative effect rather than haploinsufficiency is the mechanism leading to RP caused by RP1 mutations. On average, patients with RP1 mutations have slightly better visual acuity than patients with dominant rhodopsin mutations; otherwise, they have similarly severe disease. The wide range in severity among patients with RP1 mutations indicates that other genetic or environmental factors modulate the effect of the primary mutation.


Asunto(s)
Proteínas del Ojo/genética , Mutación del Sistema de Lectura , Mutación Missense , Retinitis Pigmentosa/genética , Adolescente , Adulto , Anciano , Adaptación a la Oscuridad , Electrorretinografía , Femenino , Genes Dominantes , Humanos , Masculino , Proteínas Asociadas a Microtúbulos , Persona de Mediana Edad , Linaje , Polimorfismo Genético , Polimorfismo Conformacional Retorcido-Simple , Retinitis Pigmentosa/fisiopatología , Rodopsina/genética , Análisis de Secuencia de ADN , Agudeza Visual , Campos Visuales
8.
J Morphol ; 262(1): 536-44, 2004 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-15352207

RESUMEN

We describe changes in the morphology of the oviductal epithelium of an oviparous skink, Lampropholis guichenoti, during the course of egg production and oviposition: to characterize the luminal epithelial changes; to provide a baseline for understanding uterine changes in viviparous species; and to establish whether the plasma membrane transformation of uterine epithelial cells is indeed a feature restricted to viviparous species. Oviducts from vitellogenic, gravid, and postgravid females were observed using scanning electron microscopy. Cellular characteristics of the oviductal epithelium previously used to determine the plasma membrane transformation were assessed morphologically. Three anatomically different areas were defined within the oviduct, but no plasma membrane transformation was observed in the oviparous skink, suggesting that this is a phenomenon particular to viviparity.


Asunto(s)
Lagartos/anatomía & histología , Lagartos/fisiología , Oviductos/fisiología , Oviductos/ultraestructura , Óvulo/fisiología , Óvulo/ultraestructura , Animales , Femenino
9.
Vet Immunol Immunopathol ; 69(2-4): 165-83, 1999 Aug 02.
Artículo en Inglés | MEDLINE | ID: mdl-10507303

RESUMEN

The focus of this study was to examine the influence of age and diet on various parameters of immune function in young and old Fox Terriers and Labrador Retrievers. Eighteen young and old dogs were utilized for this study. Young and old dogs were fed a basal diet containing an (n-6):(n-3) ratio of 25:1 for sixty days (Phase I). Half of the dogs were then switched to a diet with an (n-6):(n-3) ratio of 5:1, and all were maintained on their respective diets for an additional sixty days (Phase II). Results from these studies revealed an age-associated decline in several immune parameters measured. Both these breeds demonstrated a reduction in sheep red blood cell titers, as well as in their ability to respond to different mitogens. Interestingly, this decline was greater in Fox Terriers, suggesting a decrease in cellular proliferative capacity in lymphocytes isolated from the larger breed. Neither cytokine production or DTH response was affected by age. Diet and breed interactions resulted in a significant increase in T- and B-cell mitogen responsiveness. In contrast, supplementation with n-3 fatty acids did not affect IL-1, IL-6 or TNF-alpha production. Supplementation with n-3 fatty acids resulted in increased PGE3 production from peritoneal macrophages but had no effect on PGE2 production from peripheral blood mononuclear cells or peritoneal macrophages. The n-3 fatty acid supplementation did not influence alpha-tocopherol status although older dogs had significantly lower serum alpha-tocopherol concentrations. Oxidative status of these dogs was assessed by serum levels of malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE). Feeding an n-3-enriched diet did not affect 4-HNE levels but significantly decreased MDA levels in old dogs. In summary, this study indicates that feeding a diet containing an (n-6):(n-3) fatty acid ratio of 5:1 had a positive, rather than a negative, effect on the immune response of young or geriatric dogs.


Asunto(s)
Envejecimiento/inmunología , Grasas Insaturadas en la Dieta/farmacología , Perros/inmunología , Ácidos Grasos Omega-3/farmacología , Ácidos Grasos Insaturados/farmacología , Peroxidación de Lípido , Envejecimiento/efectos de los fármacos , Fenómenos Fisiológicos Nutricionales de los Animales , Animales , Dieta , Ácidos Grasos Omega-6 , Hipersensibilidad Tardía/inmunología , Estrés Oxidativo
10.
Tissue Cell ; 17(4): 473-90, 1985.
Artículo en Inglés | MEDLINE | ID: mdl-2413586

RESUMEN

An extracellular matrix (ECM) lies between the upper and lower epithelial layers of the wing imaginal discs of moths. Organization and composition of this extracellular matrix, as revealed by staining with ruthenium red, tannic acid, and alcian blue, changes in concert with levels of hormones in the haemolymph. The ECM of the wing imaginal disc is an environment for cellular movements. Reorganization of the matrix and increase in ecdysteroid level is coupled with the proximal----distal migration of tracheal cells as well as the distal----proximal outgrowth of sensory neurons.


Asunto(s)
Matriz Extracelular/fisiología , Hormonas de Invertebrados/fisiología , Lepidópteros/crecimiento & desarrollo , Morfogénesis , Alas de Animales/crecimiento & desarrollo , Animales , Movimiento Celular , Ecdisteroides , Epitelio/ultraestructura , Glucógeno/metabolismo , Larva , Lepidópteros/ultraestructura , Metamorfosis Biológica , Microscopía Electrónica , Neuronas/fisiología , Pupa , Coloración y Etiquetado , Tráquea/crecimiento & desarrollo
11.
J Psychosoc Nurs Ment Health Serv ; 36(4): 24-8, 1998 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-9580901

RESUMEN

1. When clients share their experiences with students, the experience helps sensitize students to the stigma of mental illness, and also facilitates the client's recovery. 2. Encouragement from staff, clinicians, other clients, and family members that they can succeed at this next step in what most often motivates a client-consumer to "try" something new or "try again". 3. Client involvement in community activities is effective in normalizing daily life experiences and in breaking down the barrier of stigma.


Asunto(s)
Instituciones de Atención Ambulatoria/organización & administración , Servicios Comunitarios de Salud Mental/organización & administración , Trastornos Mentales/rehabilitación , Práctica del Docente de Enfermería , Adulto , Familia/psicología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Relaciones Enfermero-Paciente , Satisfacción del Paciente , Esquizofrenia/rehabilitación , Tennessee
12.
J Psychosoc Nurs Ment Health Serv ; 36(4): 29-32, 1998 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-9580902

RESUMEN

1. Psychiatric rehabilitation focuses on improving a person's knowledge and skills to maximize levels of functioning and developing resources within the community to support successful living. 2. The recovery process is a lifelong process of defining new possibilities and finding new meaning and purpose in life. By accepting the limitations of what they cannot do, clients begin to discover what they are able to do and to look forward to a new beginning. 3. Facilitating success, connecting to successful role models, managing the illness, and educating clients and the community are all identified as areas that enhance hope for clients.


Asunto(s)
Trastornos Mentales/rehabilitación , Motivación , Humanos , Modelos Psicológicos , Estereotipo
13.
J Psychosoc Nurs Ment Health Serv ; 37(11): 11-9, 1999 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-10572851

RESUMEN

In the aftermath of a natural disaster, adult survivors often move through the following phases of disaster response: Heroic Phase, Honeymoon Phase, Disillusionment Phase, and Reconstruction Phase. Understanding age-related responses to traumatic events such as a tornado enables mental health clinicians to individualize appropriate interventions and prevent or diminish emotional sequelae such as post-traumatic stress disorders. Psychiatric-mental health nurses are encouraged to attend local Red Cross disaster training to be prepared should the need arise for mobilization of mental health disaster response teams in your community.


Asunto(s)
Desastres , Trastornos Mentales/etiología , Trastornos Mentales/enfermería , Enfermería Psiquiátrica/métodos , Sistemas de Socorro , Adolescente , Adulto , Factores de Edad , Anciano , Niño , Preescolar , Femenino , Humanos , Lactante , Masculino , Persona de Mediana Edad , Guías de Práctica Clínica como Asunto , Tennessee
14.
Arq. bras. med. vet. zootec. (Online) ; 70(1): 287-296, Jan.-Feb. 2018. tab
Artículo en Portugués | LILACS, VETINDEX | ID: biblio-888075

RESUMEN

O objetivo do estudo foi avaliar os efeitos da utilização de diferentes arranjos populacionais na implantação de sorgo forrageiro nas características morfogênicas e estruturais do pasto. Os tratamentos foram 22 ou 44cm entrelinhas e 12 ou 24kg de sementes ha-1. O método de pastoreio foi contínuo. Foram utilizadas 36 novilhas, com idade e peso corporal médios de 15 meses de 262kg. As variáveis morfogênicas não foram influenciadas significativamente (P>0,05) pelos arranjos populacionais e pelos períodos de avaliação, sendo obtidos taxa de alongamento e senescência foliar de 1,43 e 1,11cm dia-1afilho-1, respectivamente, taxa de aparecimento foliar e intervalo de surgimento de folhas de 0,28 folhas dia-1afilho-1 e 3,81 dias, filocrono e duração de vida foliar de 72,99 e 351,68 graus dia, nessa ordem. As características estruturais do pasto foram influenciadas pelos períodos de avaliação. Do primeiro para o terceiro período de avaliação, foi verificada uma redução de 65,53% no número de folhas em alongamento e de 47,79% no número de folhas vivas.(AU)


The objective of the study was to evaluate the effects of using different population arrangements in the implementation of sorghum in the morphogenetic and structural characteristics of the pasture. The treatments were 22 or 44cm between rows and 12 or 24kg ha-1 of seed. The grazing method was continuous. The sample consisted of 36 heifers with an average age of 15 months and average body weight of 262kg. Morphogenic variables were not significantly influenced (P>0.05) by population arrangements and evaluation periods, elongation rate and leaf senescence of 1.43 and 1.11cm afilho-1 day-1 being obtained, respectively, and leaf appearance rate of leaf appearance leaves the range of 0.28 day-1 and 1afilho 3.81 days, phyllochron and leaf duration of life of 72.99 and 351.68 degree day, in that order. The structural characteristics of the pasture were influenced by evaluation periods. From the first to the third evaluation period, a reduction of 65.53% in the number of leaves in stretching and 47.79% in the number of living leaves was verified.(AU)


Asunto(s)
Pastizales/análisis , Sorghum/anatomía & histología , Morfogénesis
15.
Nanotechnology ; 23(40): 405706, 2012 Oct 12.
Artículo en Inglés | MEDLINE | ID: mdl-22995919

RESUMEN

Si nanowires (NWs) integrated in a field effect transistor device structure are characterized using scanning electron (SEM), atomic force, and scanning Kelvin probe force (KPFM) microscopy. Reactive ion etching (RIE) and vapor-liquid-solid (VLS) growth were used to fabricate NWs between predefined electrodes. Characterization of Si NWs identified defects and/or impurities that affect the surface electronic structure. RIE NWs have defects that both SEM and KPFM analysis associate with a surface contaminant as well as defects that have a voltage dependent response indicating impurity states in the energy bandgap. In the case of VLS NWs, even after aqua regia, Au impurity levels are found to induce impurity states in the bandgap. KPFM data, when normalized to the oxide-capacitance response, also identify a subset of VLS NWs with poor electrical contact due to nanogaps and short circuits when NWs cross that is not observed in AFM images or in current-voltage measurements when NWs are connected in parallel across electrodes. The experiments and analysis presented outline a systematic method for characterizing a broad array of nanoscale systems under device operation conditions.

18.
Biomarkers ; 6(1): 33-44, 2001.
Artículo en Inglés | MEDLINE | ID: mdl-23886055

RESUMEN

Aquatic ecosystems can be chronically stressed by multiple environmental factors which originate from a variety of point and non-point sources. In addition, these stressors may vary both spatially and temporally, and, combined with synergestic and cumulative interactions of these stressors, complicate the interpretation and evaluation of stress responses in organisms. To help identify and differentiate between sources of anthropogenic stressors in aquatic systems, a diagnostic approach based on exposure-response profiles in sentinel organisms was developed from the known effects of various anthropogenic activities on biological systems. To generate these exposure-effects profiles, biomarkers of exposure were plotted against bioindicators of corresponding effects for several major anthropogenic activities including petrochemical, pulp and paper, domestic sewage, mining operations, land-development, and agricultural activities. Biomarkers of exposure to environmental stressors varied widely depending on the type of anthropogenic activity involved. Bioindicator effects, however, including histopathological lesions, bioenergetic status, growth, reproductive impairment, and community-level endpoints were similar among several of the major anthropogenic activities because responses at these higher levels are less specific to stressors than are biomarkers. This approach appears useful for helping to identify and diagnose sources of stress in environments impacted by multiple stressors. By identifying the types and sources of environmental stressors impacting key components of biological systems, aquatic ecosystems can be more effectively protected, regulated, and managed to help improve and maintain environmental quality and ecosystem fitness.

19.
Mol Pharmacol ; 22(2): 459-64, 1982 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-7144738

RESUMEN

Semiempirical molecular orbital calculations (by modified neglect of diatomic overlap method) were performed on diol epoxide metabolites of five polycyclic aromatic hydrocarbons (PAHs)--benzene, naphthalene, phenanthrene, chrysene, and benzo[a]pyrene (BP)--to gain insight into the various carcinogenic potencies of these compounds. Opening of the epoxide rings of the diol epoxides was calculated to be exothermic for all of the PAHs investigated. The bay-region diol epoxides of BP were calculated to open spontaneously to the triol carbonium ion upon protonation. For the bay-region trans- and cis-diequatorial diol epoxides of 5-methylchrysene the methyl group destabilized the epoxide. These results suggest that the conformation of the saturated, angular benzo-ring is important in determining bay-region epoxide stability. Conformational flexibility of the aromatic ring system is offered as one reason for partial stabilizing of bay-region epoxides. These results also suggest that the existence and potentiation of PAH carcinogenicity is correlated with the lack of stability of the bay-region epoxide ring. Considerations of thermochemical stability have value in predictions of carcinogenic potency.


Asunto(s)
Carcinógenos/metabolismo , Compuestos Epoxi , Éteres Cíclicos , Compuestos Policíclicos/metabolismo , Animales , ADN/metabolismo , Estabilidad de Medicamentos , Humanos , Conformación Molecular , Relación Estructura-Actividad
20.
Ecotoxicol Environ Saf ; 37(1): 53-61, 1997 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-9212336

RESUMEN

Bioindicators of fish health were measured from 1989 through 1994 in populations of redbreast sunfish (Lepomis auritus) at three sites within a stream receiving inputs of mixed contaminants from an industrial facility, and at two reference sites. Bioindicator responses differed for fish from contaminated and reference sites throughout the study period, but temporal trends at contaminated sites reflected improved water quality associated with pollution-control efforts. Temporal variability unrelated to contaminant exposure strongly influenced the response of bioindicators at both reference and contaminated sites, but spatial variability rarely influenced these responses. Temporal variability was less influential on slower responding indicators at higher levels of biological organization. The diverse response characteristics of indicators increased the ability to differentiate natural from anthropogenic sources of variability. Integrated bioindicator responses were compared among site-year groups by multivariate canonical analysis. The primary canonical variable, associated with differences in growth, exhibited trends consistent with the timing of pollution-control efforts. Two indicators of contaminant exposure (7-ethoxyresorufin O-deethylase activity and polychlorinated biphenyls in fish muscle) also exhibited trends consistent with the timing of pollution-control efforts, but the likelihood of possible mechanistic linkages cannot be assessed with available data.


Asunto(s)
Perciformes/fisiología , Contaminantes Químicos del Agua/toxicidad , Animales , Carga Corporal (Radioterapia) , Citocromo P-450 CYP1A1/metabolismo , Agua Dulce/análisis , Indicadores de Salud , Mercurio/análisis , Músculo Esquelético/química , Músculo Esquelético/metabolismo , Estado Nutricional , Perciformes/metabolismo , Bifenilos Policlorados/análisis , Bifenilos Policlorados/metabolismo , Factores de Tiempo
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