RESUMEN
Ecologically relevant toxicity tests may provide the best protection of sensitive aquatic fauna, but without established culturing or test methodology for such organisms, results may be unreliable and difficult to repeat. Further, field-collected organisms may not be feasible for routine testing purposes, as often required for permitted discharges. This study examined the feasibility of testing two field-collected mayflies, Isonychia bicolor and Maccaffertium spp., over a 1-year period. Seasonal comparisons of availability indicated I. bicolor and Maccaffertium spp. were most abundant during the winter months, resulting in 31 and 49 % of total organisms collected in 2009, while summer was the most difficult time to collect either species. Initial testing in January 2009 resulted in the highest no observable effect concentration (NOEC) values for survivorship (8 g NaCl for I. bicolor and 4 and 8 g NaCl/L for Maccaffertium spp.) when tested at 9 °C. Subsequent tests conducted at 20-23 °C resulted in 7-day NOEC values substantially lower (mean = 1.44 and 1.59 g NaCl/L). Geometric means of exuviae indicated a dose-dependent response for I. bicolor exposed to NaCl, while no dose-dependent response was observed for Maccaffertium spp. with average number of molts varying from 4.93 in the 0.5 g NaCl/L concentration to 3.80 for control organisms followed by 2.24 (1 g NaCl/L). Averages again increased to 3.09 in the 2 g NaCl/L concentration, but declined in the highest concentrations (4-10 g NaCl/L). Based on the results of this feasibility study, field-collected mayflies appear to be too unpredictable in test responses, and therefore, such tests would be unreliable as stand-alone indicators of effluent toxicity.
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Monitoreo del Ambiente/métodos , Insectos , Pruebas de Toxicidad/normas , Contaminantes Químicos del Agua/toxicidad , Animales , Monitoreo del Ambiente/normas , Estaciones del Año , Sensibilidad y Especificidad , Cloruro de Sodio/toxicidadRESUMEN
We aim to identify preoperative factors at diagnosis which could predict whether women undergoing wide local excision (WLE) would require further operations. 1593 screen-detected invasive and non-invasive breast cancers were reviewed. Age, presence of ductal carcinoma in situ (DCIS), invasive cancer size on mammography, mammographic sign, tumour type, grade and confidence of the radiologist in malignancy were compared. 83%(1315/1593) of women had a WLE. Of these, 70%(919/1315) had a single operation, and 30%(396/1315) multiple operations. These included repeat WLE to clear margins (60%(238/396)), mastectomy (34%(133/396)) and axillary dissection (6%(25/396)). The presence of mammographic microcalcification, lobular carcinoma and grade 2 malignancy on core biopsy were independent risk factors for multiple operations on multivariate analysis. Women with mammographic DCIS >30 mm were 3.4 times more likely to undergo repeat surgery than those with smaller foci. The multidisciplinary team should pay particular attention to these factors when planning surgery.
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Neoplasias de la Mama/cirugía , Carcinoma Ductal de Mama/cirugía , Carcinoma Intraductal no Infiltrante/cirugía , Carcinoma Lobular/cirugía , Escisión del Ganglio Linfático/estadística & datos numéricos , Mastectomía/estadística & datos numéricos , Adulto , Anciano , Anciano de 80 o más Años , Biopsia con Aguja Gruesa , Mama/patología , Neoplasias de la Mama/diagnóstico , Carcinoma Ductal de Mama/diagnóstico por imagen , Carcinoma Ductal de Mama/patología , Carcinoma Intraductal no Infiltrante/diagnóstico por imagen , Carcinoma Intraductal no Infiltrante/patología , Carcinoma Lobular/diagnóstico por imagen , Carcinoma Lobular/patología , Técnicas de Apoyo para la Decisión , Detección Precoz del Cáncer , Femenino , Humanos , Modelos Logísticos , Mamografía , Mastectomía/métodos , Persona de Mediana Edad , Análisis Multivariante , Clasificación del Tumor , Reoperación/estadística & datos numéricos , Factores de Riesgo , Carga TumoralAsunto(s)
Dolor Abdominal/etiología , Nefropatías Diabéticas/diagnóstico por imagen , Enfisema/diagnóstico por imagen , Pielonefritis/diagnóstico por imagen , Anciano de 80 o más Años , Nefropatías Diabéticas/complicaciones , Enfisema/complicaciones , Humanos , Masculino , Pielonefritis/complicaciones , Tomografía Computarizada por Rayos XRESUMEN
AIM: To audit the use of inferior vena cava (IVC) filter insertions at three UK centres over 12 years to assess whether trends in filter use in the UK mirrored those seen elsewhere. MATERIALS AND METHODS: Radiology department databases were interrogated for IVC filter insertions and removals between 1994 and 2006. Reports for these interventions, along with prior and subsequent imaging reports, were analysed. Follow-up data were obtained when available. RESULTS: Five hundred and sixteen filters were placed with a significant year-on-year trend towards increasing use. Fifty-seven percent of filters placed were for absolute indications and 37% for relative indications. The filters were used for prophylaxis in 6% of patients in the absence of proven pulmonary embolism (PE) or deep vein thrombosis (DVT). A retrievable filter was used in 74% of cases with retrieval attempted in 40% of these and no evidence of an increasing rate of retrieval over time. A significant complication related to insertion or retrieval was encountered in 0.4 and 1% of procedures, respectively. Mean 24 h and 30 day mortalities were 1 and 8%, respectively. There was an absence of organized follow-up at all three centres. CONCLUSION: IVC filter use in the UK is increasing. The use of retrievable filters has not resulted in increased filter retrieval. Filter insertion and retrieval is associated with a low risk of significant complication, but lack of systematic follow-up limits conclusions regarding safety and efficacy.
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Remoción de Dispositivos/estadística & datos numéricos , Filtros de Vena Cava/estadística & datos numéricos , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Toma de Decisiones , Remoción de Dispositivos/mortalidad , Remoción de Dispositivos/tendencias , Femenino , Humanos , Masculino , Auditoría Médica , Persona de Mediana Edad , Implantación de Prótesis/efectos adversos , Implantación de Prótesis/mortalidad , Implantación de Prótesis/tendencias , Embolia Pulmonar/diagnóstico por imagen , Embolia Pulmonar/prevención & control , Radiografía , Resultado del Tratamiento , Reino Unido , Filtros de Vena Cava/efectos adversos , Vena Cava Inferior/diagnóstico por imagen , Vena Cava Inferior/cirugía , Trombosis de la Vena/diagnóstico por imagen , Trombosis de la Vena/prevención & control , Adulto JovenRESUMEN
A survey of infectious bronchitis virus (IBV) genotypes in poultry flocks in selected countries in Western Europe was carried out between March 2002 and December 2006. Identification of IBV was by reverse transcriptase-polymerase chain reaction of RNA extracted from oropharyngeal swabs taken from poultry flocks exhibiting signs of clinical disease thought to be attributable to IBV. Part of the hypervariable S1 gene of IBV was sequenced to differentiate between the various genotypes. During the survey, 4103 samples were processed, of which 2419 (59%) were positive for IBV. The predominant IBV genotypes detected were 793B and Massachusetts. The third and fourth most common genotypes were two new economically important field types: Italy02, and a virus similar to genotypes originally detected in China called QX. Analysis of the partial S1 sequences of the genotypes detected suggested that approximately 50% of all 793B, Massachusetts types and D274 IBVs were identical to the homologous commercially available live vaccines. Since 2004 the prevalence of Italy02 (present in all countries from which samples were received) has been declining in all countries except Spain, where it appeared to be the predominant genotype. Since 2004 an IBV genotype has been detected in Holland, Germany, Belgium and France similar to QX and the incidence has increased. QX was not detected in the United Kingdom or Spain. When detections thought to be attributable to vaccines were removed, the dominant genotype in France and Europe overall was 793B; in Germany, Holland and Belgium, it was QX-like IBV; and in the United Kingdom and Spain the dominant genotype was Italy02. The present study is the first to identify the prevalence of both Italy02 and QX field-type variants in poultry flocks in Western Europe. Several novel genotypes have also been detected.
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Pollos/virología , Infecciones por Coronavirus/veterinaria , Virus de la Bronquitis Infecciosa/genética , Enfermedades de las Aves de Corral/virología , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa/veterinaria , Animales , Infecciones por Coronavirus/epidemiología , Infecciones por Coronavirus/virología , Europa (Continente)/epidemiología , Genotipo , Virus de la Bronquitis Infecciosa/clasificación , Filogenia , Enfermedades de las Aves de Corral/epidemiología , Factores de TiempoRESUMEN
We describe the imaging appearances of a patient with bilateral, synchronous, multiloculated renal cell carcinoma with a predominantly cystic nature. The patient had progressive chronic renal failure. He was initially erroneously diagnosed as having autosomal dominant polycystic kidney disease (ADPKD) on the basis of the imaging findings. We believe this to be the first report describing bilateral synchronous renal carcinomas replacing the renal parenchyma imitating ADPKD.
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Carcinoma de Células Renales/diagnóstico , Neoplasias Renales/diagnóstico , Riñón Poliquístico Autosómico Dominante/diagnóstico , Carcinoma de Células Renales/complicaciones , Diagnóstico Diferencial , Humanos , Fallo Renal Crónico/etiología , Neoplasias Renales/complicaciones , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Tomografía Computarizada por Rayos XRESUMEN
The Clinch River system of southwestern Virginia and northeastern Tennessee is among the most biodiverse aquatic ecosystems of the United States, but its fauna are in decline. Unionidae (freshwater mussel) species are a major component of the Clinch's aquatic community, and their decline is well documented. Point-source discharges within the Clinch drainage are few, and primary stressors on the biota are believed to originate from non-point sources that are transported into the mainstem by tributaries. Currently, the relative influences of tributaries as stressors on aquatic biota are unclear. We studied 19 major tributaries of the free-flowing Upper Clinch River, developed an Ecotoxicological Rating (ETR) utilizing eight parameters, and assessed stream quality among land use categories using the ETR rating system. Biological, toxicological, habitat, and chemical variables were measured in each tributary, near its confluence with the Clinch. Geographic Information System software was used to quantify land use within each tributary watershed; all tributary watersheds are predominately forested, but agricultural, mining, and developed land uses (urban, transportation) are also present. ETRs indicated that the tributaries draining mining-influenced watersheds had greater potential impact on the mainstem than those draining agricultural or forested watersheds, because of poor benthic macroinvertebrate scores. ETRs ranged from 44 to 63, on a 100-point scale, for mining-influenced tributaries compared to agricultural (57-86) and forested tributaries (64-91). Mean ETRs for the mining-influenced tributaries (51) were significantly different than ETRs from agricultural and forested streams (75 and 80, respectively), and the presence of developed land uses had no significant relationship with ETRs.
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Minería , Ríos , Contaminantes Químicos del Agua/toxicidad , Agricultura , Animales , Corbicula/efectos de los fármacos , Corbicula/crecimiento & desarrollo , Daphnia/efectos de los fármacos , Daphnia/fisiología , Monitoreo del Ambiente , Reproducción/efectos de los fármacos , Árboles , Unionidae , Urbanización , Virginia , Abastecimiento de AguaRESUMEN
Many studies investigating the ecotoxicological impacts of industrial effluents on fresh-water biota utilize standardized test species such as the daphnids, Ceriodaphnia dubia, Daphnia magna, and the fathead minnow, Pimephales promelas. Such species may not be the most predictive or ecologically relevant gauges of the responses of instream benthic macroinvertebrates to certain stressors, such as total dissolved solids. An indigenous species approach should be adopted, using a sensitive benthic collector-filterer following development of practical laboratory bioassays. In the Leading Creek Watershed (southeast Ohio), an aggregated approximately 99% reduction in mean mayfly abundance for all impacted sites was observed below a coal-mine effluent with mean specific conductivity (SC) of 8,109 (7,750-8,750) microS cm(-1). The mayfly, Isonychia, was exposed for 7-days to a simulation of this effluent, in lotic microcosms. Based on lowest observable adverse effect concentrations, Isonychia survival was a more sensitive endpoint to SC (1,562 microS cm(-1)) than were 7-day C. dubia survival and fecundity (3,730 microS cm(-1)). Isonychia molting, a potentially more sensitive endpoint, was also examined. Using traditional test species to assess discharges to surface water alone may not adequately protect benthic macroinvertebrate assemblages in systems impaired by discharges high in SC.
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Bioensayo , Minas de Carbón , Monitoreo del Ambiente/métodos , Insectos , Metales/toxicidad , Contaminantes Químicos del Agua/toxicidad , Animales , Ohio , Estados UnidosRESUMEN
Population-based insurance systems using longitudinal administrative data and record linkage techniques have helped create "information-rich" environments in several sites around the world. The output of five research groups using administrative data (Oxford, Western Australia, and three Canadian centres: Manitoba, Ontario and British Columbia) was analysed from contacts with the research groups and through use of the National Library of Medicine's PubMed and Medical Subject Headings (MeSH) categories. MeSH words "utilization", "economics", "physicians", and "physician practice patterns" more frequently characterized the research by the three Canadian centres than that of the other sites. With core funding for deliverables negotiated with the provincial health ministries, Canadian researchers have been more likely to use linked databases for policy analyses. Manitoba examples highlight the capabilities associated with these information-rich environments. They include the ability to analyse interventions longitudinally; to compare regions, areas and hospitals in defined populations; to combine information on patients and physicians; to add up expenditures for different services within the Canadian health-care system; and to examine population health issues in areas such as education and family services. Well-organized data and the capability for rapid response have been critical for timely policy analysis in Manitoba. A number of successes are mentioned; less successful efforts to influence practice patterns and to modify the internal workings of hospitals are noted. Investments in filling gaps in data collection and in enriching existing data would facilitate additional research. Planning and managing health care for an entire population has benefited greatly from the development of an information-rich environment.
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Bases de Datos como Asunto , Investigación sobre Servicios de Salud/métodos , Informática en Salud Pública , Sistema de Registros , Colombia Británica , Planificación en Salud Comunitaria , Inglaterra , Reforma de la Atención de Salud , Estado de Salud , Humanos , Internet , Manitoba , Registro Médico Coordinado , Ontario , Descriptores , Australia OccidentalRESUMEN
The U.S. Environmental Protection Agency has not recommended water quality criteria (WQC) to protect aquatic life from elevated sodium and sulfate concentrations, such as those associated with the coal-processing effluent of Meigs County Mine #31. This discharge, received by a tributary of the Leading Creek Watershed (SE Ohio), had a mean specific conductivity (SC) of 8,109 (7,750-8,750) microS/cm and total metal concentrations below acute WQC. The mean 48-h LC(50) for Ceriodaphnia dubia in the effluent was 6,713 +/- 99 microS/cm; mean 48-h survival was 44% for study sites downstream of the effluent. The best indicators of impairment used in this study were Ceriodaphnia fecundity, in situ Corbicula fluminea growth, EPT minus Hydropsychidae (richness and relative abundance), and relative Ephemeroptera abundance. Mayflies, reduced by more than 99% below the effluent, were absent from all but the furthest downstream study site. SC was strongly correlated with Corbicula growth (r = -0.9755, p = 0.0009) and EPT minus Hydropsychidae richness (r = -0.8756, p < 0.0001), suggesting the effluent was primarily responsible for biotic impairment. Our results indicated that SC levels, a measure of dissolved solids, in the Leading Creek Watershed that exceeded approximately 3,700 microS/cm impaired sensitive aquatic fauna.
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Minas de Carbón , Agua Dulce/química , Invertebrados/crecimiento & desarrollo , Contaminantes Químicos del Agua/toxicidad , Animales , Escarabajos/efectos de los fármacos , Escarabajos/crecimiento & desarrollo , Daphnia/efectos de los fármacos , Daphnia/crecimiento & desarrollo , Invertebrados/efectos de los fármacos , Moluscos/efectos de los fármacos , Moluscos/crecimiento & desarrollo , Ohio , Perciformes/crecimiento & desarrolloRESUMEN
The Ely Creek watershed in Lee County, VA, USA, contains an abundance of abandoned mined land areas with acid mine drainage (AMD) that contaminate the majority of the creek and its confluence into Stone Creek. Acidic pH measurements ranged from 2.73 to 5.2 at several stations throughout the watershed. Sediments had high concentrations of iron (approximately 10,000 mg kg-1), aluminum (approximately 1,500 mg kg-1), magnesium (approximately 400 mg kg-1) and manganese (approximately 150 mg kg-1), and habitat was partially to non-supporting at half of the stations due to sedimentation. Benthic macroinvertebrate surveys at six of 20 stations sampled in the watershed yielded no macroinvertebrates, while eight others had total abundances of only one to nine organisms. Four reference stations contained > or = 100 organisms and at least 13 different taxa. Asian clam in situ toxicity testing supported field survey results. Laboratory, 10-day survival/impairment sediments tests with Daphnia magna and Chironomus tentans and 48-h water column bioassays with Ceriodaphnia dubia indicated environmental stress to a lesser degree. Ten parameters that were directly influenced by AMD through physical, chemical, ecological and toxicological endpoints were assimilated into an ecotoxicological rating (ETR) to form a score of 0-100 points for the 20 sampling stations, and the lower the score the greater the AMD stress. Twelve of the 15 sampling stations influenced by AMD received an ETR score of 13.75-57.5, which were categorized as severely stressed (i.e. comprised the < 60 percentile category) and worthy of the highest priority for future ecological restoration activities in the watershed.
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Ácidos/toxicidad , Invertebrados/efectos de los fármacos , Metales Pesados/toxicidad , Minería , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/toxicidad , Ácidos/análisis , Animales , Bivalvos/efectos de los fármacos , Bivalvos/crecimiento & desarrollo , Chironomidae/efectos de los fármacos , Chironomidae/crecimiento & desarrollo , Daphnia/efectos de los fármacos , Daphnia/crecimiento & desarrollo , Ecosistema , Ambiente , Monitoreo del Ambiente/métodos , Invertebrados/crecimiento & desarrollo , Metales Pesados/análisis , Sensibilidad y Especificidad , Contaminantes del Suelo/análisis , Análisis de Supervivencia , VirginiaRESUMEN
The pattern of replenishment of LH secretory granule stores in sheep pituitary gonadotrophs, after an induced LH surge, was determined by immunogold localisation at the ultrastructural level by electron microscopy. Twenty-four Welsh Mountain ewes were initially synchronised with progestagen devices for 14 days before luteolysis was induced by a prostaglandin F(2 alpha) analogue, cloprostenol. A further 24 h later, a preovulatory LH surge was induced by intravenous injection of a GnRH agonist, buserelin. Animals were divided into four groups (n=6) and blood sampled at 2 h intervals from 4 h prior, to 18 h after, buserelin administration and then at infrequent intervals (1 to 8 h) thereafter until death. Pulse profiles of LH were also obtained by an additional collection of blood samples within a 6 h window directly preceding death. Groups of animals were killed at 24, 48, 72 or 96 h after buserelin treatment. Pituitaries were dissected and processed for transmission electron microscopy and frozen for later molecular biological analysis. A characteristic preovulatory surge of LH was observed in all animals. The cytoplasm of gonadotrophs, in animals killed 24 h after buserelin treatment, was completely empty of secretory granules. This was associated with diminutive pituitary LH content, low pituitary GnRH binding levels and an almost complete absence (one pulse in one animal) of LH pulsatile secretion. Despite the lack of apparent secretory activity, clusters of exposed LH beta label present within the cytoplasm at this time and constant LHbeta mRNA expression levels irrespective of tissue collection time, suggest that the cell is actively synthesising LHbeta. The formation of sparse numbers of small LH beta immuno-labelled electron-dense secretory granules was apparent at 48 h after buserelin treatment, and replenishment of LH beta immuno-labelled granule stores continued until total granule numbers had increased two-fold (P<0.01) by 96 h post-treatment. Affiliated with granule replenishment was a significant increase in pituitary LH content (P<0.01), pituitary GnRH binding levels (P<0.01) and the restoration of LH pulsatile secretion. Despite the replenishment of granule stores with time, cytoplasmic area did not vary. These results suggest that restoration of pulsatile LH secretion after a preovulatory LH surge is related to replenishment of LH beta secretory granule stores and an increase in GnRH binding levels.
Asunto(s)
Fase Folicular/metabolismo , Hormona Luteinizante/biosíntesis , Hipófisis/metabolismo , Vesículas Secretoras/metabolismo , Ovinos/metabolismo , Análisis de Varianza , Animales , Buserelina/farmacología , Femenino , Fármacos para la Fertilidad Femenina/farmacología , Hormona Liberadora de Gonadotropina/metabolismo , Hormona Luteinizante/sangre , Hormona Luteinizante/genética , Microscopía Inmunoelectrónica , Hipófisis/efectos de los fármacos , Hipófisis/ultraestructura , Unión Proteica , Tasa de Secreción , Vesículas Secretoras/ultraestructura , Factores de TiempoRESUMEN
In recent years, ascites research has centred on gaining an increased understanding of pulmonary hypertension syndrome together with the potential role of primary cardiac pathologies. The impact at a cellular level of factors which trigger ascites and substances that protect against it has also been documented. Primary pulmonary hypertension has been induced when birds are exposed to hypoxia during incubation. The conditions experienced during this phase of development may impact on the ability of the bird to regulate its basal metabolic rate through endocrine signals controlled by thyroid activity. The extent of ventilation in the lung influences the ability of the bird to oxygenate haemoglobin. Ventilation/ perfusion mismatches may occur prior to or post-hatching. This factor has been studied extensively using the pulmonary artery/bronchus clamp model. At high altitude, a decreased ventilation/perfusion ratio may occur following the effective increase in physiological dead space due to the lowered oxygen tension at the level of the parabronchi. This explains the mechanism by which ascites is triggered by hypoxia in this particular situation. The effects of ascites are ameliorated by the use of beta agonists and dietary arginine, which act by increasing ventilation and blood flow in the lungs and thus correcting a ventilation/perfusion mismatch. Transient bacterial and viral infections may also influence the induction of pulmonary hypertension. The increases in blood viscosity associated with ascites are most probably a consequence of the condition rather than a cause. A bird may alleviate the effects of pulmonary hypertension by decreasing blood viscosity through inhibition of platelet function, increased erythrocyte deformability and the production of coronary relaxants. Evidence is accumulating that primary cardiac pathology may be associated with a number of ascites cases. Broilers that subsequently develop ascites, exhibit lower heart rates than their normal flock mates. Furthermore, during ascites, hypoxic broilers exhibit bradycardia as opposed to the expected tachycardia. In these cases, a tachycardia induced by feed restriction may protect the bird by raising its cardiac output. Right atrio-ventricular regurgitant flow velocities in chickens are relatively slow compared with similar regurgitant flows induced by pulmonary hypertension in other species. The conduction system in the avian heart is specialized and contains a recurrent bundle branch that innervates the right atrio-ventricular valve, thus initiating active valve closure before right ventricular systole. This predisposes the heart to right ventricular volume overload through a valvular incompetance following a failure of valvular innervation. The resultant elevated diastolic wall stress can trigger the production of angiotensin II and its converting enzyme, which mediate ventricular hypertrophy. Subclinical myocardial damage, irrespective of its cause, can be detected by the presence of troponin T in the blood. Reactive oxygen species may damage cell membranes compromising cellular function in a number of body systems. A positive correlation exists between oxidized glutathione concentrations and right ventricular weight ratio. This indicates a failure to cope with oxidative stress at the level of the respiratory membrane. It is not known if it is possible to modulate levels of antioxidants at this location and hence protect the bird. The final description of the ascites aetiology may lie in the concept of a circuit of events between the cardiac, pulmonary and vascular systems that satisfy the metabolic requirements of the bird. A deficit in one of these systems, at a level that prevents adequate compensation from other components, triggers the pathological cascade that results in the end point of clinical ascites.
RESUMEN
OBJECTIVES: To create an inexpensive, simple, accurate, and noninvasive device to evaluate the character of a male's urinary stream. METHODS: The results of a formal in-office uroflow study performed on 50 symptomatic men were compared with those of the same men using the Streamtest cup. RESULTS: All men with a urine flow of 12 mL/s or greater reached or exceeded the red line on the Streamtest cup. No patient whose stream was less than 11 mL/s was able to reach the red line. CONCLUSIONS: Uroflowmetry is an excellent study in diagnosing, managing, and monitoring the treatment of urinary obstructive disease secondary to benign prostatic hyperplasia. The Streamtest cup can provide both the patient and the physician with a clinically accurate visual assessment of an individual's urine flow at a significant cost savings over other testing means. The Streamtest cup when compared with a formal in-office uroflow study provided clinically similar results in separating obstructive uropathy from a normal urinary flow.
Asunto(s)
Urodinámica , Urología/instrumentación , Diseño de Equipo , Humanos , MasculinoRESUMEN
Changes in LH secretory granules in pituitary gonadotrophs throughout the sheep oestrous cycle were determined by immunogold localisation of LH at ultrastructural level by electron microscopy. Oestrous cycles in Welsh Mountain ewes were initially synchronised with progestagen sponges and studies carried out in the subsequent cycle. Animals were allocated at random to six groups each of five animals, one killed on day 12 of the luteal phase and the other groups after prostaglandin (PG)-induced luteal regression at PG plus 18 h (early follicular phase), oestrus (PG plus 33.6 +/- 1.0 h), oestrus plus 9 h just before the preovulatory LH surge, 1 h after GnRH agonist-induced LH surge at PG plus 48 h (mid-LH surge) and oestrus plus 24 h, after the preovulatory LH surge. Blood samples collected throughout confirmed the pulsatile secretion of LH before and the timing in relation to the preovulatory LH surge. Pituitaries were dissected and processed for transmission electron microscopy and frozen for later extraction of mRNA. Only a single type of LH cell was present in the sheep pituitary. In the luteal phase, LH-immunopositive secretory granules were distributed throughout the cytoplasm in 80% of cells while in 20% of cells granules were polarised to the region of the cell next to a vascular sinusoid. The percentage of polarised cells increased during the follicular phase to 45% at oestrus, 75% at oestrus plus 9 h just before the LH surge and 90% in mid-LH surge. Cell size increased in parallel with polarisation. Gonadotrophs after the LH surge were almost totally devoid of LH granules but prominent LH beta immunoreactivity was observed in the rough endoplasmic reticulum. Analysis of granule diameters revealed a single class of granules with a maximum diameter of 300 nm. Polarised cells had significantly fewer 130-150 nm granules than non-polarised cells, suggesting preferential exocytosis of LH-containing granules of this size from polarised cells. Northern analysis showed that LH beta mRNA levels decreased from luteal through the follicular phase. These results suggest that the preovulatory LH surge in sheep is not related to a change in synthesis of LH but to a progressive recruitment of gonadotrophs into a releasing state, priming, as indicated by polarisation of secretory granules to the region of the cell next to the vascular system.
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Gránulos Citoplasmáticos/ultraestructura , Fase Folicular , Hormona Luteinizante/fisiología , Hipófisis/fisiología , Ovinos/fisiología , Animales , Northern Blotting , Gránulos Citoplasmáticos/metabolismo , Femenino , Expresión Génica , Hormona Luteinizante/genética , Hormona Luteinizante/metabolismo , Microscopía Electrónica , Microscopía Inmunoelectrónica , Hipófisis/ultraestructura , ARN Mensajero/análisis , Tasa de SecreciónRESUMEN
Observations made with a scanning electron microscope of the claw horn and underlying soft tissues of young pigs fed a normal diet supplemented with 1 mg d-biotin/kg of feed were compared with observations on a similar group receiving no additional biotin. Supplementary biotin affected the structure of the coronary epidermis; there was an increase in the density of the horn tubules in the stratum medium, the horny squames in the stratum medium were more tightly packed and the tubules were more clearly defined in the pigs receiving biotin. The width of the band of intertubular horn adjacent to the laminae was greater in the claws of control pigs.