RESUMEN

Lithium (Li) toxicity in plants is, at a minimum, a function of Li(+) concentration, exposure time, species and growth conditions. Most plant studies with Li(+) focus on short-term acute exposures. This study examines short- and long-term effects of Li(+) exposure in Arabidopsis with Li(+) uptake studies and measured shoot mRNA transcript abundance levels in treated and control plants. Stress, pathogen-response and arabinogalactan protein genes were typically more up-regulated in older (chronic, low level) Li(+)-treatment plants and in the much younger plants from acute high-level exposures. The gene regulation behavior of high-level Li(+) resembled prior studies due to its influence on: inositol synthesis, 1-aminocyclopropane-1-carboxylate synthases and membrane ion transport. In contrast, chronically-exposed plants had gene regulation responses that were indicative of pathogen, cold, and heavy-metal stress, cell wall degradation, ethylene production, signal transduction, and calcium-release modulation. Acute Li(+) exposure phenocopies magnesium-deficiency symptoms and is associated with elevated expression of stress response genes that could lead to consumption of metabolic and transcriptional energy reserves and the dedication of more resources to cell development. In contrast, chronic Li(+) exposure increases expression signal transduction genes. The identification of new Li(+)-sensitive genes and a gene-based "response plan" for acute and chronic Li(+) exposure are delineated.

Asunto(s)

Arabidopsis/crecimiento & desarrollo , Arabidopsis/genética , Regulación del Desarrollo de la Expresión Génica/efectos de los fármacos , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Litio/farmacología , Desarrollo de la Planta/genética , Arabidopsis/efectos de los fármacos , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Regulación hacia Abajo/efectos de los fármacos , Regulación hacia Abajo/genética , Ontología de Genes , Genes de Plantas , Hidroponía , Redes y Vías Metabólicas/efectos de los fármacos , Redes y Vías Metabólicas/genética , Familia de Multigenes , Desarrollo de la Planta/efectos de los fármacos , ARN Mensajero/genética , ARN Mensajero/metabolismo , Suelo , Factores de Tiempo , Regulación hacia Arriba/efectos de los fármacos , Regulación hacia Arriba/genética

RESUMEN

To assess the applicability of latex cell coatings as an 'off-the-shelf' biocatalyst, the effect of osmoprotectants, temperature, humidity and O2 on preservation of H2 production in Rhodopseudomonas palustris coatings was evaluated. Immediately following latex coating coalescence (24 h) and for up to 2 weeks of dry storage, rehydrated coatings containing different osmoprotectants displayed similar rates of H2 production. Beyond 2 weeks of storage, sorbitol-treated coatings lost all H2 production activity, whereas considerable H2 production was still detected in sucrose- and trehalose-stabilized coatings. The relative humidity level at which the coatings were stored had a significant impact on the recovery and subsequent rates of H2 production. After 4 weeks storage under air at 60% humidity, coatings produced only trace amounts of H2 (0-0.1% headspace accumulation), whereas those stored at < 5% humidity retained 27-53% of their H2 production activity after 8 weeks of storage. When stored in argon at < 5% humidity and room temperature, R. palustris coatings retained full H2 production activity for 3 months, implicating oxidative damage as a key factor limiting coating storage. Overall, the results demonstrate that biocatalytic latex coatings are an attractive cell immobilization platform for preservation of bioactivity in the dry state.

Asunto(s)

Reactores Biológicos/microbiología , Biotecnología/métodos , Células Inmovilizadas/metabolismo , Hidrógeno/metabolismo , Rhodopseudomonas/metabolismo , Desecación , Látex , Rhodopseudomonas/efectos de los fármacos , Rhodopseudomonas/efectos de la radiación , Temperatura

RESUMEN

The actinobacterium Kineococcus radiotolerans is highly resistant to ionizing radiation, desiccation, and oxidative stress, though the underlying biochemical mechanisms are unknown. The purpose of this study was to explore a possible linkage between the uptake of transition metals and extreme resistance to ionizing radiation and oxidative stress. The effects of six different divalent cationic metals on growth were examined in the absence of ionizing radiation. None of the metals tested were stimulatory, though cobalt was inhibitory to growth. In contrast, copper supplementation dramatically increased colony formation during chronic irradiation. K. radiotolerans exhibited specific uptake and intracellular accumulation of copper, compared to only a weak response to both iron and manganese supplementation. Copper accumulation sensitized cells to hydrogen peroxide. Acute-irradiation-induced DNA damage levels were similar in the copper-loaded culture and the age-synchronized no-copper control culture, though low-molecular-weight DNA was more persistent during postirradiation recovery in the Cu-loaded culture. Still, the estimated times for genome restoration differed by only 2 h between treatments. While we cannot discount the possibility that copper fulfills an unexpectedly important biochemical role in a low-radioactivity environment, K. radiotolerans has a high capacity for intracellular copper sequestration and presumably efficiently coordinated oxidative stress defenses and detoxification systems, which confers cross-protection from the damaging effects of ionizing radiation.

Asunto(s)

Actinomycetales/crecimiento & desarrollo , Actinomycetales/metabolismo , Actinomycetales/efectos de la radiación , Cobre/farmacocinética , Reparación del ADN/efectos de la radiación , Rayos gamma , Actinomycetales/ultraestructura , Electroforesis en Gel de Campo Pulsado , Espectrometría de Masas , Microscopía Electrónica , Estrés Oxidativo/efectos de la radiación

RESUMEN

The search for microorganisms that are capable of catalyzing the reduction of an electrode within a fuel cell has primarily been focused on bacteria that operate mesobiotically. Bacteria that function optimally under extreme conditions are beginning to be examined because they may serve as more effective catalysts (higher activity, greater stability, longer life, capable of utilizing a broader range of fuels) in microbial fuel cells. An examination of marine sediment from temperate waters (Charleston, SC) proved to be a good source of thermophilic electrode-reducing bacteria. Electric current normalized to the surface area of graphite electrodes was approximately ten times greater when sediment fuel cells were incubated at 60 degrees C (209 to 254 mA/m(2)) vs 22 degrees C (10 to 22 mA/m(2)). Electricity-generating communities were selected in sediment fuel cells and then maintained without sediment or synthetic electron-carrying mediators in single-chambered fuel cells. Current was generated when cellulose or acetate was added as a substrate to the cells. The 16S ribosomal ribonucleic acid genes from the heavy biofilms that formed on the graphite anodes of acetate-fed fuel cells were cloned and sequenced. The preponderance of the clones (54 of 80) was most related to a Gram-positive thermophile, Thermincola carboxydophila (99% similarity). The remainder of clones from the community was most related to T. carboxydophila, or uncultured Firmicutes and Deferribacteres. Overall, the data indicate that temperate aquatic sediments are a good source of thermophilic electrode-reducing bacteria.

Asunto(s)

Electricidad , Sedimentos Geológicos/microbiología , Bacterias Grampositivas/aislamiento & purificación , Bacterias Grampositivas/metabolismo , Acetatos/metabolismo , Biopelículas/crecimiento & desarrollo , Celulosa/metabolismo , ADN Bacteriano/química , ADN Bacteriano/genética , ADN Ribosómico/química , ADN Ribosómico/genética , Electrodos , Bacterias Grampositivas/clasificación , Bacterias Grampositivas/genética , Grafito/metabolismo , Calor , Datos de Secuencia Molecular , Oxidación-Reducción , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN , South Carolina

RESUMEN

Desulfitobacterium hafniense strain DCB2 generates electricity in microbial fuel cells (MFCs) when humic acids or the humate analog anthraquinone-2,6-disulfonate (AQDS) is added as an electron-carrying mediator. When utilizing formate as fuel, the Gram-positive, spore-forming bacterium generated up to 400 mW/m2 of cathode surface area in a single-chamber MFC with a platinum-containing air-fed cathode. Hydrogen, lactate, pyruvate, and ethanol supported electricity generation, but acetate, propionate, and butyrate did not. Scanning electron microscopy indicated that strain DCB2 colonized the surface of a current-generating anode but not of an unconnected electrode. The electricity was recovered fully within minutes after the exchange of the medium in the anode chamber and within a week after an exposure of a colonized anode to 90 degrees C for 20 min. Of the six strains of Desulfitobacteria tested, all of which would reduce AQDS, only D. hafniense strain DCB2 continued to reduce AQDS and generate electricity for more than 24 h, indicating that reduction of the humate analog alone is insufficient to sustain electrode reduction.

Asunto(s)

Fuentes de Energía Bioeléctrica , Desulfitobacterium/fisiología , Electricidad , Antraquinonas/metabolismo , Desulfitobacterium/ultraestructura , Electrodos/microbiología , Etanol/metabolismo , Formiatos/metabolismo , Hidrógeno/metabolismo , Ácido Láctico/metabolismo , Microscopía Electrónica de Rastreo , Oxidación-Reducción , Ácido Pirúvico/metabolismo , Factores de Tiempo

RESUMEN

Chlorinated hydroquinones of biological origin are fully dechlorinated to 1,4-dihydroquinone by anaerobic bacteria such as Desulfitobacterium spp. (C. E. Milliken, G. P. Meier, J. E. M. Watts, K. R. Sowers, and H. D. May, Appl. Environ. Microbiol. 70:385-392, 2004). In the present study, mixed microbial communities from Baltimore Harbor sediment and a pure culture of Desulfitobacterium sp. strain PCE1 were discovered to demethylate, reductively dehydroxylate, and dechlorinate chlorinated hydroquinones into chlorophenols. Mixed microbial cultures from a freshwater source and several other desulfitobacteria in pure culture did not perform these reactions. Desulfitobacterium sp. strain PCE1 degraded 2,3,5,6-tetrachloro-4-methoxyphenol, a metabolite of basidiomycete fungi, to 2,3,5,6-tetrachlorophenol and 2,3,5-trichlorophenol, recalcitrant compounds that are primarily synthesized anthropogenically.

Asunto(s)

Clorofenoles/metabolismo , Desulfitobacterium/metabolismo , Hidroquinonas/metabolismo , Anaerobiosis , Baltimore , Biotransformación , Sedimentos Geológicos/microbiología , Hidroquinonas/química

RESUMEN

The synthesis and degradation of anthropogenic and natural organohalides are the basis of a global halogen cycle. Chlorinated hydroquinone metabolites (CHMs) synthesized by basidiomycete fungi and present in wetland and forest soil are constituents of that cycle. Anaerobic dehalogenating bacteria coexist with basidiomycete fungi in soils and sediments, but little is known about the fate of these halogenated fungal compounds. In sediment microcosms, the CHMs 2,3,5,6-tetrachloro-1,4-dimethoxybenzene and 2,3,5,6-tetrachloro-4-methoxyphenol (TCMP) were anaerobically demethylated to tetrachlorohydroquinone (TCHQ). Subsequently, TCHQ was converted to trichlorohydroquinone and 2,5-dichlorohydroquinone (2,5-DCHQ) in freshwater and estuarine enrichment cultures. Screening of several dehalogenating bacteria revealed that Desulfitobacterium hafniense strains DCB2 and PCP1, Desulfitobacterium chlororespirans strain Co23, and Desulfitobacterium dehalogenans JW/DU1 sequentially dechlorinate TCMP to 2,3,5-trichloro-4-methoxyphenol and 3,5-dichloro-4-methoxyphenol (3,5-DCMP). After a lag, these strains demethylate 3,5-DCMP to 2,6-DCHQ, which is then completely dechlorinated to 1,4-dihydroquinone (HQ). 2,5-DCHQ accumulated as an intermediate during the dechlorination of TCHQ to HQ by the TCMP-degrading desulfitobacteria. HQ accumulation following TCMP or TCHQ dechlorination was transient and became undetectable after 14 days, which suggests mineralization of the fungal compounds. This is the first report on the anaerobic degradation of fungal CHMs, and it establishes a fundamental role for microbial reductive degradation of natural organochlorides in the global halogen cycle.

Asunto(s)

Basidiomycota/metabolismo , Desulfitobacterium/metabolismo , Hidrocarburos Clorados/metabolismo , Hidroquinonas/metabolismo , Anaerobiosis , Basidiomycota/crecimiento & desarrollo , Biodegradación Ambiental , Cloro/metabolismo , Medios de Cultivo , Desulfitobacterium/crecimiento & desarrollo , Hidroquinonas/química , Metilación , Microbiología del Suelo

RESUMEN

INTRODUCTION: The Walter Reed Army Institute of Research used the Electronic Surveillance System for the Early Notification of Community-Based Epidemics (ESSENCE) to conduct population-based behavioral health surveillance among military-health-system beneficiaries. The study analyzed the effectiveness of using prescribing patterns of psychotropic medications to monitor changes in a community's behavioral health status. OBJECTIVES: The objectives of this study were to 1) determine the feasibility of tracking psychiatric illnesses by monitoring prescriptions for psychiatric medications; 2) assess how often psychiatric medications are prescribed for patients with no record of psychiatric illness; 3) determine at what types of clinics these medications are prescribed most often and what other diagnoses are attributed to these patients; and 4) analyze data for potential changes in the population's mental health after high-stress events. METHODS: Correlation analysis and calculations of sensitivity and specificity were used to determine how well prescription medications correlate with outpatient diagnoses and how well they serve as proxies for outpatient diagnoses. A descriptive analysis was conducted of the types of clinics (e.g., primary care, behavioral health, or other specialty clinics) treating patients and the associated percentage of concurrence between prescriptions and diagnostic codes. RESULTS: In military treatment facilities, a diagnosis of depression or anxiety correlated significantly (r = 0.82) with antidepressant or anxiolytic prescriptions. Sensitivity of prescriptions when compared with outpatient visits was 0.76, and specificity was 0.94. Among those patients who visited a primary care clinic either the day before or the same day as an antidepressant or anxiolytic prescription was filled, 60.1% did not receive a diagnosis of any mental health disorder. Behavioral health clinics had the highest correlation between diagnoses and prescriptions; specialty clinics had the lowest. CONCLUSIONS: Behavioral health trends in a population can be monitored by automated analysis of prescribing patterns alone. This method might be a rapid indicator of needed mental health interventions after acute stress-inducing events and be more sensitive than tracking diagnoses alone.

Asunto(s)

Utilización de Medicamentos , Conductas Relacionadas con la Salud , Trastornos Mentales/epidemiología , Vigilancia de la Población/métodos , Informática en Salud Pública/instrumentación , Brotes de Enfermedades/prevención & control , Humanos , Acontecimientos que Cambian la Vida , Trastornos Mentales/tratamiento farmacológico , Psicotrópicos/uso terapéutico

RESUMEN

BACKGROUND: Catheter-based myocardial gene transfer (GTx) has not been previously tested in human subjects. Accordingly, we performed a pilot study to investigate the feasibility and safety of catheter-based myocardial GTx of naked plasmid DNA encoding vascular endothelial growth factor-2 (phVEGF-2) in patients with chronic myocardial ischemia. METHODS AND RESULTS: A steerable, deflectable 8F catheter incorporating a 27-guage needle was advanced percutaneously to the left ventricular myocardium of 6 patients with chronic myocardial ischemia. Patients were randomized (1:1) to receive phVEGF-2 (total dose, 200 microgram), which was administered as 6 injections into ischemic myocardium (total, 6.0 mL), or placebo (mock procedure). Injections were guided by NOGA left ventricular electromechanical mapping. Patients initially randomized to placebo became eligible for phVEGF-2 GTx if they had no clinical improvement 90 days after their initial procedure. Catheter injections (n=36) caused no changes in heart rate or blood pressure. No sustained ventricular arrhythmias, ECG evidence of infarction, or ventricular perforations were observed. phVEGF-2-transfected patients experienced reduced angina (before versus after GTx, 36.2+/-2.3 versus 3.5+/-1.2 episodes/week) and reduced nitroglycerin consumption (33.8+/-2.3 versus 4.1+/-1.5 tablets/week) for up to 360 days after GTx; reduced ischemia by electromechanical mapping (mean area of ischemia, 10.2+/-3.5 versus 2.8+/-1.6 cm(2), P=0.04); and improved myocardial perfusion by SPECT-sestamibi scanning for up to 90 days after GTx when compared with images obtained after control procedure. Conclusions-This randomized trial of catheter-based phVEGF-2 myocardial GTx provides preliminary indications regarding the feasibility, safety, and potential efficacy of percutaneous myocardial GTx to human left ventricular myocardium.

Asunto(s)

Cateterismo Cardíaco , ADN Recombinante/administración & dosificación , Isquemia Miocárdica/terapia , Neovascularización Fisiológica/genética , Transfección , Factores de Crecimiento Endotelial Vascular/uso terapéutico , Función Ventricular Izquierda , Anciano , ADN Recombinante/genética , ADN Recombinante/uso terapéutico , Estudios de Factibilidad , Femenino , Ventrículos Cardíacos/fisiopatología , Humanos , Masculino , Isquemia Miocárdica/diagnóstico por imagen , Isquemia Miocárdica/fisiopatología , Proyectos Piloto , Seguridad , Tomografía Computarizada de Emisión de Fotón Único , Resultado del Tratamiento , Factores de Crecimiento Endotelial Vascular/genética

RESUMEN

BACKGROUND: NOGA left ventricular (LV) electromechanical mapping (EMM) can be used to distinguish among infarcted, ischemic, and normal myocardium. We investigated the use of percutaneous LV EMM to assess the efficacy of myocardial gene transfer (GTx) of naked plasmid DNA encoding for vascular endothelial growth factor (phVEGF(165)), administered during surgery by direct myocardial injection in patients with chronic myocardial ischemia. METHODS AND RESULTS: A total of 13 consecutive patients (8 men, mean age 60.1+/-2. 3 years) with chronic stable angina due to angiographically documented coronary artery disease, all of whom had failed conventional therapy (drugs, PTCA, and/or CABG), were treated with direct myocardial injection of phVEGF(165) via a minithoracotomy. Foci of ischemic myocardium were identified on LV EMM by preserved viability associated with an impairment in linear local shortening. Myocardial viability, defined by mean unipolar and bipolar voltage recordings >/=5 and >/=2 mV, respectively, did not change significantly after GTx. Analysis of linear local shortening in areas of myocardial ischemia, however, disclosed significant improvement after (15.26+/-0.98%) versus before (9.94+/-1.53%, P:=0. 004) phVEGF(165) GTx. The area of ischemic myocardium was consequently reduced from 6.45+/-1.37 cm(2) before GTx to 0.95+/-0. 41 cm(2) after GTx (P:=0.001). These findings corresponded to improved perfusion scores calculated from single-photon emission CT-sestamibi myocardial perfusion scans recorded at rest (7.4+/-2.1 before GTx versus 4.5+/-1.4 after GTx, P:=0.009) and after pharmacological stress (12.8+/-2.7 before GTx versus 8.5+/-1.7 after GTx, P:=0.047). CONCLUSIONS: The results of EMM constitute objective evidence that phVEGF(165) GTx augments perfusion of ischemic myocardium. These findings, together with reduction in the size of the defects documented at rest by serial single-photon emission CT-sestamibi imaging, suggest that phVEGF(165) GTx may successfully rescue foci of hibernating myocardium.

Asunto(s)

Factores de Crecimiento Endotelial/genética , Terapia Genética/métodos , Linfocinas/genética , Isquemia Miocárdica/terapia , Neovascularización Fisiológica , Inductores de la Angiogénesis/uso terapéutico , Circulación Coronaria/efectos de los fármacos , Electrocardiografía/métodos , Factores de Crecimiento Endotelial/uso terapéutico , Técnicas de Transferencia de Gen , Corazón/diagnóstico por imagen , Corazón/fisiopatología , Humanos , Linfocinas/uso terapéutico , Masculino , Microinyecciones , Persona de Mediana Edad , Isquemia Miocárdica/diagnóstico por imagen , Isquemia Miocárdica/fisiopatología , Plásmidos/uso terapéutico , Cintigrafía , Toracotomía , Factor A de Crecimiento Endotelial Vascular , Factores de Crecimiento Endotelial Vascular , Función Ventricular Izquierda

Asunto(s)

Factores de Crecimiento Endotelial/genética , Técnicas de Transferencia de Gen , Linfocinas/genética , Isquemia Miocárdica/diagnóstico por imagen , Isquemia Miocárdica/terapia , Miocardio , Anciano , Anciano de 80 o más Años , Ecocardiografía , Expresión Génica , Humanos , Masculino , Factor A de Crecimiento Endotelial Vascular , Factores de Crecimiento Endotelial Vascular

RESUMEN

OBJECTIVES: This study investigated the feasibility and safety of percutaneous, catheter-based myocardial gene transfer. BACKGROUND: Direct myocardial gene transfer has, to date, required direct injection via an open thoracotomy. METHODS: Electroanatomical mapping was performed to establish the site of left ventricular (LV) gene transfer. A steerable, deformable 7F catheter with a 27G needle, which can be advanced 3 to 5 mm beyond its distal tip, was then directed to previously acquired map sites, the needle was advanced, and injections were made into the LV myocardium. RESULTS: In two pigs in which methylene blue dye was injected, discretely stained LV sites were observed at necropsy in each pig, corresponding to the injection sites indicated prospectively by the endocardial map. In six pigs in which the injection catheter was used to deliver plasmid using cytomegalovirus promoter/enhancer, encoding nuclear-specific LacZ gene (pCMV-nlsLacZ) (50 microg/ml) to a single LV myocardial region, peak beta-galactosidase activity after five days (relative light units [RLU], mean 135,333+/-28,239, range = 31,508 to 192,748) was documented in the target area of myocardial injection in each pig. Percutaneous gene transfer of pCMV-nlsLacZ (50 microg/ml) was also performed in two pigs with an ameroid constrictor applied to the left circumflex coronary artery, in each pig, peak beta-galactosidase activity after five days (214,851 and 23,140 RLU) was documented at the injection site. All pigs survived until sacrifice, and no complications were observed with either the mapping or the injection procedures. CONCLUSIONS: Percutaneous myocardial gene transfer can be successfully achieved in normal and ischemic myocardium without significant morbidity or mortality. These findings establish the potential for minimally invasive cardiovascular gene transfer.

Asunto(s)

Técnicas de Transferencia de Gen , Terapia Genética/métodos , Isquemia Miocárdica/terapia , Función Ventricular , Animales , Cateterismo Cardíaco , Electrofisiología/métodos , Estudios de Factibilidad , Humanos , Plásmidos/genética , Porcinos , beta-Galactosidasa/metabolismo

RESUMEN

SUMMARY This paper considers several lesbian-produced safe sex tapes which engage pornographic vernacular with a dual purpose, offering both a very pointed counter to the dearth of erotic imagery depicting lesbian sex/sexuality specifically by and for women, but also functioning as pedagogical (self-help) tools for rethinking safe sex.

RESUMEN

Stanniocalcin (STC) is a calcium- and phosphate-regulating hormone produced by the corpuscles of Stannius in fishes. A rise in ion calcium (Ca2+) levels is the principal stimulus for secretion, and the hormone acts on the gills, gut, and kidneys to restore normocalcemia. The STC-producing cells in marine fishes are metabolically more active and secrete more hormone than those in freshwater fishes, which has been attributed to the higher calcium content of seawater placing a greater burden on the organ systems governing Ca2+ homeostasis. In this study we have addressed the question of whether or not the STC cells in marine fishes are more sensitive to Ca2+, by comparing the secretagogic effects of Ca2+ in freshwater- and seawater-adapted coho salmon. The results showed that the STC cells were equally Ca(2+)-sensitive in the two groups. Therefore, in spite of the fact that the STC cells are more active in marine fishes this requires no apparent adjustment in cellular sensitivity to calcium.

Asunto(s)

Calcio/farmacología , Glicoproteínas/análisis , Glicoproteínas/metabolismo , Hormonas/análisis , Hormonas/metabolismo , Oncorhynchus kisutch/sangre , Adaptación Fisiológica , Animales , Calcio/sangre , Agua Dulce , Glicoproteínas/sangre , Hormonas/sangre , Prolactina/sangre , Prolactina/efectos de los fármacos , Agua de Mar , Factores de Tiempo

RESUMEN

We have investigated the influence of the cytokine tumor necrosis factor alpha (TNF alpha), an important mediator of sepsis, on in vitro hamster diaphragm contractility. Costal diaphragm strips were excised and mounted on an experimental apparatus consisting of a force transducer and servomotor. Preparations were randomized to incubation in one of the following solutions: (1) indomethacin 10(-6) M (n = 5); (2) TNF alpha (0.1 ng/ml) (n = 5); (3) TNF alpha (500 ng/ml) (n = 5); and (4) TNF alpha (500 ng/ml) plus indomethacin (10(-6)) (n = 5). Baseline contractile parameters measured at optimal length included twitch and tetanic tension, half relaxation time, time to peak tension, force frequency response (10-80 Hz), and fatigability to response to repetitive stimulation. After 90-min incubation in one of the solutions, an identical stimulation protocol was repeated. Initial twitch and tetanus parameters were similar between groups. Maximal twitch tension and tetanic tension decreased significantly, as did tetanic stimulations at 10-80 Hz in the TNF group (500 ng/ml) (p < 0.05). Coincubation with indomethacin decreased but did not completely abolish changes in diaphragm function caused by the higher dose of TNF. There were no significant changes in twitch or tetanus parameters, or in response to repetitive stimulation after incubation in the lower dose TNF group (0.1 ng/ml). We conclude that TNF causes impairment of in vitro diaphragm contractility at high incubation concentrations of TNF and that this effect can be partially blocked by prostaglandin synthetase inhibition. No significant deleterious effect on in vitro contractility was detected at concentrations of TNF similar to serum levels in human sepsis.

Asunto(s)

Inhibidores de la Ciclooxigenasa/farmacología , Diafragma/efectos de los fármacos , Dinoprostona/antagonistas & inhibidores , Indometacina/farmacología , Contracción Isométrica/efectos de los fármacos , Factor de Necrosis Tumoral alfa/farmacología , Animales , Cricetinae , Inhibidores de la Ciclooxigenasa/administración & dosificación , Diafragma/anatomía & histología , Indometacina/administración & dosificación , Masculino , Mesocricetus , Fatiga Muscular/efectos de los fármacos , Relajación Muscular/efectos de los fármacos , Tamaño de los Órganos , Factor de Necrosis Tumoral alfa/administración & dosificación , Factor de Necrosis Tumoral alfa/antagonistas & inhibidores

RESUMEN

The corpuscles of Stannius are responsible for the synthesis and secretion of stanniocalcin (STC), a glycoprotein hormone that regulates calcium and phosphate homeostasis in fishes through its actions on the gills and kidneys. The corpuscles of Stannius and STC are considered to be an endocrine system that is unique to fishes. In this report, we provide evidence for the existence of STC-like proteins in vertebrates other than fishes, in particular, humans. By using a well-characterized RIA for salmon STC, sera from vertebrates as diverse as sharks and humans contained measurable levels of STC-like immunoreactivity in the concentration range commonly observed in fishes, and all of these sera exhibited parallelism in the assay. By using Western blot analysis, proteins were also identified in human kidney extracts that shared several properties with the fish hormone in addition to their cross-reactivity with salmon STC antiserum. The same antiserum was used to identify a discrete population of cells in human kidney tubules that could be the source of serum immunoreactivity. Human kidney extracts containing the STC-immunoreactive proteins also had STC-related effects when injected into fishes. Collectively, the data suggest that STC may be more widespread among the vertebrates than is currently accepted.

Asunto(s)

Calcio/metabolismo , Glicoproteínas/análisis , Hormonas/análisis , Riñón/química , Animales , Bioensayo , Biopsia , Western Blotting , Femenino , Peces , Branquias/efectos de los fármacos , Branquias/metabolismo , Glicoproteínas/aislamiento & purificación , Glicoproteínas/farmacología , Anguila Babosa , Hormonas/aislamiento & purificación , Hormonas/farmacología , Humanos , Inmunohistoquímica , Riñón/citología , Riñón/patología , Masculino , Ratas , Ratas Sprague-Dawley , Salmón , Tiburones , Trucha , Urodelos

RESUMEN

Stanniocalcin (STC) is an inhibitor of gill Ca2+ transport that is produced by the corpuscles of Stannius, endocrine glands in bony fish. In young rainbow trout (Oncorhynchus mykiss), there are cyclical changes in the rate of gill Ca2+ transport, with alternating phases of accelerated and reduced uptake every 14 days. Previous studies by our laboratory have established that the responsiveness of young trout to the inhibitory effects of exogenous STC is dependent on this cycle. Trout are highly responsive to STC at peaks of Ca2+ uptake and unresponsive at nadirs, which has led us to suggest that the gill Ca2+ transport cycle may be regulated by a reciprocal cycle in the levels of plasma STC. In this report, we have further characterized the gill Ca2+ transport cycle in salmonids and investigated the role of STC in its regulation. Our results showed that the cycle is synchronous and is likely a characteristic feature in all salmonids but that it varies in amplitude between species. Surprisingly, we observed no correlation between circulating levels of radioimmunoassayable STC and the rate of gill Ca2+ transport in trout. To address this apparent contradiction, trout fry were passively immunized with STC antiserum to determine if there were variable amounts of bioactive STC in the circulation, at times when trout were either more or less sensitive to exogenous STC. We observed that during the times when trout were responsive to STC treatment (i.e., cycle peaks), passive immunization had no effect on the rate of gill Ca2+ transport in fish from the same population, indicating that there were low levels of bioactive STC in the circulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Asunto(s)

Calcio/metabolismo , Branquias/metabolismo , Glicoproteínas/sangre , Hormonas/sangre , Trucha/fisiología , Animales , Transporte Biológico , Glicoproteínas/inmunología , Glicoproteínas/fisiología , Hormona del Crecimiento/sangre , Homeostasis/fisiología , Hormonas/inmunología , Hormonas/fisiología , Inmunización Pasiva , Periodicidad , Prolactina/sangre , Salmón/fisiología , Especificidad de la Especie

RESUMEN

Stanniocalcin (STC), a calcium-regulating glycoprotein hormone isolated from the corpuscles of Stannius of salmon, was tested for effects on bone and calcium metabolism in mammalian species (rats and mice). STC generally failed to alter serum calcium of parathyroidectomized rats at concentrations equimolar with effective concentrations of parathyroid hormone (PTH). STC did not increase cAMP in ROS 17/2.8 or UMR-108 osteosarcoma cells, OK kidney cells, fetal rat limb bones, or neonatal mouse calvariae, and similarly failed to increase urinary cAMP in rats. STC did not consistently stimulate resorption in any of the rodent bone culture systems, although variable resorptive responses were elicited in fetal mouse calvariae. The results indicate that this fish hormone has limited, if any, PTH-like activity on calcium metabolism in mammalian systems.

Asunto(s)

Huesos/efectos de los fármacos , Glicoproteínas/farmacología , Hormonas , Hormona Paratiroidea/farmacología , Animales , Resorción Ósea , Calcio/sangre , Bovinos , Línea Celular , AMP Cíclico/análisis , Cinética , Ratones , Técnicas de Cultivo de Órganos , Ratas , Ratas Endogámicas , Salmón , Células Tumorales Cultivadas

RESUMEN

Stanniocalcin (STC) is a hormone that is synthesized and secreted by the corpuscles of stannius (CS), endocrine glands that are unique to the bony fishes. The hormone inhibits Ca2+ transport from the aquatic environment into the bloodstream by way of the gills. Previous in vitro studies by our laboratory have shown that STC secretion is positively regulated by Ca2+ in a time- and dose-dependent fashion. In this report, we have examined circulating levels of STC in free-swimming, cannulated rainbow trout and how hormone levels are affected by surgical stress and intra-arterial infusions of mono and divalent cations. In addition, the plasma hormone has been concentrated by immunoaffinity chromatography and characterized by Western blot analysis. The results suggest that the in vivo response of the CS is extremely rapid and Ca(2+)-specific and that STC circulates in multiple molecular weight forms.

Asunto(s)

Glicoproteínas/sangre , Hormonas , Animales , Western Blotting , Calcio/sangre , Calcio/fisiología , Cloruro de Calcio/farmacología , Glicoproteínas/genética , Glicosilación , Homeostasis , Precursores de Proteínas/genética , Radioinmunoensayo , Cloruro de Sodio/farmacología , Estrés Fisiológico/sangre , Trucha

RESUMEN

A rainbow trout fry bioassay based on 45Ca uptake was used to compare the effects of pure coho salmon teleocalcin (TC) and several synthetic peptide fragments of TC. Calcium uptake in the fry exhibited a cycle, with an amplitude variation of 3.3 to 48.8 mumol.kg-1.hr-1 and a periodicity of 8 to 21 days. The N-terminal 1-20 amino acid peptides of both eel and salmon TC significantly inhibited 45Ca uptake at the high point of the calcium uptake cycle (up to 75%), although the effective doses of the peptides on a molar basis were 20 to 200 times that of the intact molecule. In contrast, the C-terminal fragment of eel TC (amino acids 202-231) did not have an inhibitory effect on calcium uptake. Instead, it significantly enhanced 45Ca uptake in trout fry (up to sixfold) at the low point of the calcium uptake cycle.

Asunto(s)

Calcio/metabolismo , Glicoproteínas/farmacología , Hormonas , Fragmentos de Péptidos/farmacología , Salmonidae/metabolismo , Trucha/metabolismo , Secuencia de Aminoácidos , Animales , Bioensayo , Anguilas , Datos de Secuencia Molecular , Salmón