Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 15 de 15
Filtrar
1.
Astrobiology ; 21(6): 741-756, 2021 06.
Artículo en Inglés | MEDLINE | ID: mdl-33885329

RESUMEN

In Earth's deep continental subsurface, where groundwaters are often isolated for >106 to 109 years, energy released by radionuclides within rock produces oxidants and reductants that drive metabolisms of non-photosynthetic microorganisms. Similar processes could support past and present life in the martian subsurface. Sulfate-reducing microorganisms are common in Earth's deep subsurface, often using hydrogen derived directly from radiolysis of pore water and sulfate derived from oxidation of rock-matrix-hosted sulfides by radiolytically derived oxidants. Radiolysis thus produces redox energy to support a deep biosphere in groundwaters isolated from surface substrate input for millions to billions of years on Earth. Here, we demonstrate that radiolysis by itself could produce sufficient redox energy to sustain a habitable environment in the subsurface of present-day Mars, one in which Earth-like microorganisms could survive wherever groundwater exists. We show that the source localities for many martian meteorites are capable of producing sufficient redox nutrients to sustain up to millions of sulfate-reducing microbial cells per kilogram rock via radiolysis alone, comparable to cell densities observed in many regions of Earth's deep subsurface. Additionally, we calculate variability in supportable sulfate-reducing cell densities between the martian meteorite source regions. Our results demonstrate that martian subsurface groundwaters, where present, would largely be habitable for sulfate-reducing bacteria from a redox energy perspective via radiolysis alone. We present evidence for crustal regions that could support especially high cell densities, including zones with high sulfide concentrations, which could be targeted by future subsurface exploration missions.


Asunto(s)
Marte , Meteoroides , Planeta Tierra , Medio Ambiente Extraterrestre , Hidrógeno
2.
Behav Brain Res ; 331: 241-253, 2017 07 28.
Artículo en Inglés | MEDLINE | ID: mdl-28549651

RESUMEN

Tenascin-C (TnC) is an extracellular matrix glycoprotein implicated in a variety of processes ranging from brain development to synaptic plasticity in the adult vertebrates. Although the role of the TnC gene in regulation of behavior has been investigated, it remained elusive how TnC deficiency interacts with the environment in shaping the behavioral phenotype. To address this, 3-week-old TnC+/+ and TnC-/- male mice were housed over an 8-week period in standard conditions (SC), or enriched environment (EE). A comprehensive battery of tests was used in behavioral phenotyping. When housed in SC, TnC-/- mice showed spontaneous nocturnal hyperactivity, as well as poor sensorimotor coordination and low swimming velocity. However, housing of TnC-/- mice in EE abolished hyperlocomotion, led to faster habituation to novel environment, strengthened the grasp of fore limbs and partially improved movement coordination, while the swimming ability remained deficient. Conversely, TnC deficiency attenuated both the beneficial effects of EE on learning/memory capacity and the anxiolytic effect of EE in reducing the level of acrophobia. This study expands the existing knowledge about the phenotype associated with TnC deficiency, and reveals that the effect of genetic background on the behavioral response could be altered by post-weaning housing in a highly stimulating environment.


Asunto(s)
Conducta Animal/fisiología , Aprendizaje/fisiología , Plasticidad Neuronal/genética , Tenascina/metabolismo , Animales , Masculino , Ratones Endogámicos C57BL , Ratones Transgénicos , Plasticidad Neuronal/fisiología , Fenotipo , Tenascina/deficiencia
3.
Neuroscience ; 292: 1-12, 2015 Apr 30.
Artículo en Inglés | MEDLINE | ID: mdl-25701126

RESUMEN

Experimental autoimmune encephalomyelitis (EAE) is a model of multiple sclerosis (MS), inflammatory, demyelinating and neurodegenerative disease of the central nervous system (CNS). Clinically manifested EAE can be induced in Dark Agouti (DA) rats, but not in Albino Oxford (AO) rats by immunization with spinal cord homogenate (SCH) and complete Freund's adjuvant (CFA). Matrix metalloproteinases (MMP) play important roles in various steps of MS and EAE pathogenesis. Expression of gelatinases MMP2 and MMP9, their activator MMP14 and their inhibitor tissue inhibitor of MMP (TIMP)1 in the CNS of AO and DA rats immunized with SCH+CFA was determined. Expression of mRNA for MMP2, MMP9 and MMP14 was higher and expression of TIMP1 mRNA was lower in AO rats. However, gelatinase activity in spinal cords was higher in samples obtained from DA rats. Further, while there was no strain difference in MMP2 and MMP9 mRNA expression in lymph nodes of the immunized rats, gelatinase activity was higher in DA rats. This activity was reduced by antiinflammatory cytokines interleukin (IL)-10 and IL-4. Interestingly, gelatinase activity was detected in the nuclei of cells within the CNS, but not of those in lymph nodes. Our results imply that posttranscriptional regulation of MMP2 and MMP9 expression and/or function determines low gelatinase activity within the CNS and in immune cells of EAE-resistant AO rats.


Asunto(s)
Encefalomielitis Autoinmune Experimental/enzimología , Metaloproteinasa 14 de la Matriz/metabolismo , Metaloproteinasa 2 de la Matriz/metabolismo , Metaloproteinasa 9 de la Matriz/metabolismo , Inhibidor Tisular de Metaloproteinasa-1/metabolismo , Animales , Núcleo Celular/enzimología , Predisposición Genética a la Enfermedad , Interleucina-10/metabolismo , Interleucina-4/metabolismo , Ganglios Linfáticos/enzimología , ARN Mensajero/metabolismo , Ratas , Médula Espinal/enzimología
4.
Angew Chem Int Ed Engl ; 51(50): 12495-8, 2012 Dec 07.
Artículo en Inglés | MEDLINE | ID: mdl-23129151

RESUMEN

Active in alkaline environment: The activity of nickel, silver, and copper catalysts for the electrochemical transformation of water to molecular hydrogen in alkaline solutions was enhanced by modification of the metal surfaces by Ni(OH)(2) (see picture; I = current density and η = overpotential). The hydrogen evolution reaction rate on a Ni electrode modified by Ni(OH)(2) nanoclusters is about four times higher than on a bare Ni surface.

5.
Acta Chir Iugosl ; 57(3): 111-3, 2010.
Artículo en Inglés | MEDLINE | ID: mdl-21066994

RESUMEN

OBJECTIVE: to present relatively uncommon surgical procedure for the treatment of localized prostate cancer. MATERIAL AND METHODS: Six patients with localized prostate cancer (PCa) underwent perineal radical prostatectomy (PRP) from 2006 to 2010. The average age was 65 +/- 5.2 years. The average preoperative PSA was 7.8 +/- 1.3 ng/ml. Two patients had pT2b stage, while four had pT2c stage. Gleason score ranged from 4-7. RESULTS: All patients had negative surgical margins. Average operative time was 109 +/- 20 minutes and average blood loss was 525 +/- 180 ml. The urethral catheter was removed after 12 days in all patients except one, who required prolonged catheterization due to urinary fistula. All patients were continent after three months. Average postoperative PSA was 0.07 +/- 0.03 ng/ml. CONCLUSION: Perineal radical prostatectomy is valuable surgical procedure that provides good oncological results as well as urinary and sexual function.


Asunto(s)
Prostatectomía/métodos , Anciano , Humanos , Masculino , Neoplasias de la Próstata/patología , Neoplasias de la Próstata/cirugía
6.
Nat Chem ; 1(6): 466-72, 2009 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-21378914

RESUMEN

The classic models of metal electrode-electrolyte interfaces generally focus on either covalent interactions between adsorbates and solid surfaces or on long-range electrolyte-metal electrostatic interactions. Here we demonstrate that these traditional models are insufficient. To understand electrocatalytic trends in the oxygen reduction reaction (ORR), the hydrogen oxidation reaction (HOR) and the oxidation of methanol on platinum surfaces in alkaline electrolytes, non-covalent interactions must be considered. We find that non-covalent interactions between hydrated alkali metal cations M(+)(H(2)O)(x) and adsorbed OH (OH(ad)) species increase in the same order as the hydration energies of the corresponding cations (Li(+) >> Na(+) > K(+) > Cs(+)) and also correspond to an increase in the concentration of OH(ad)-M(+)(H(2)O)(x) clusters at the interface. These trends are inversely proportional to the activities of the ORR, the HOR and the oxidation of methanol on platinum (Cs(+) > K(+) > Na(+) >> Li(+)), which suggests that the clusters block the platinum active sites for electrocatalytic reactions.


Asunto(s)
Suministros de Energía Eléctrica , Platino (Metal)/química , Catálisis , Electroquímica , Electrodos , Electrólitos/química , Metales Alcalinos/química , Metanol/química , Oxidación-Reducción , Propiedades de Superficie
7.
Faraday Discuss ; 140: 25-40; discussion 93-112, 2008.
Artículo en Inglés | MEDLINE | ID: mdl-19213308

RESUMEN

Some issues of the current state of understanding in the surface electrochemistry are discussed, with emphases on the role of specifically adsorbing anions in hydrogen adsorption and oxide formation, adsorption and ordering of molecular adsorbates and metal ions, metal deposition, restructuring and stability of surface atoms, and kinetics of electrochemical reactions.


Asunto(s)
Aniones/química , Catálisis , Electroquímica/tendencias , Electrodos/tendencias , Transporte de Electrón , Modelos Químicos , Oxidación-Reducción , Propiedades de Superficie
8.
J Phys Chem B ; 109(30): 14433-40, 2005 Aug 04.
Artículo en Inglés | MEDLINE | ID: mdl-16852816

RESUMEN

The particle size effect on the formation of OH adlayer, the CO bulk oxidation, and the oxygen reduction reaction (ORR) have been studied on Pt nanoparticles in perchloric acid electrolyte. From measurements of the CO displacement charge at controlled potential, the corresponding surface charge density versus potential curves yielded the potentials of total zero charge (pztc), which shifts approximately 35 mV negative by decreasing the particle size from 30 nm down to 1 nm. As a consequence, the energy of adsorption of OH is more enhanced, that is, at the same potential the surface coverage with OH increases by decreasing the particle size, which in turn affects the catalytic reactions thereon. The impact of the electronically induced potential shift in the OH adsorption is demonstrated at the CO bulk oxidation, in which adsorbed OH is an educt species and promotes the reaction, and the ORR, where it can act as a surface site blocking species and inhibits the reaction.

9.
J Phys Chem B ; 109(2): 678-80, 2005 Jan 20.
Artículo en Inglés | MEDLINE | ID: mdl-16866425

RESUMEN

Vibrational properties of CO have been studied on Pt(111) in acid and alkaline electrolytes by synchronous measurements of CO oxidation current (0.5 mV/s) and IRAS spectra (one spectrum for every 1 mV). We found that in acid solutions the frequency-tuning rate (dnu(CO)/dE) as well as the potential-dependent bandwidth (dDeltanu1/2/dE) deviates from expected linear relationships. This unusual potential-dependent behavior is interpreted in terms of compression/dissipation of CO islands during the CO oxidation, engendered by competitive adsorption between inactive anions from a supporting electrolyte and the reactive OH species.


Asunto(s)
Monóxido de Carbono/química , Hidróxidos/química , Percloratos/química , Platino (Metal)/química , Compuestos de Potasio/química , Ácidos Sulfúricos/química , Electrodos , Electrólitos/química , Oxidación-Reducción , Soluciones/química , Propiedades de Superficie , Vibración
10.
Acta Chir Iugosl ; 51(3): 57-60, 2004.
Artículo en Inglés | MEDLINE | ID: mdl-16018367

RESUMEN

The tension--free vaginal tape procedure (TVT) has been regarded as a safe, minimally invasive method for the treatment of female stress urinary incontinence. In a prospective multicenter study we evaluated safety and efficacy of TVT procedure for the treatment of female stress incontinence. From 1998. to 2003, a total of 42 patients, mean age 60 years (range 34-76) with urodynamically verified stress urinary incontinence underwent the TVT procedure. The mean follow-up period was 28 months (range 14 to 32). Intra- and postoperative complications were few, including bladder perforations (4.7%), vaginal hematoma (2.4%), complete urinary retention (2.4%), transient urinary retention (19%) and urinary tract infection (7.1%). Postoperatively, voiding time and functional urethral length significant increased. The subjective and objective cure rates were 85.7% and 90.5%, respectively. We conclude that the TVT procedure is associated with high cure rate and low morbidity.


Asunto(s)
Incontinencia Urinaria de Esfuerzo/cirugía , Adulto , Anciano , Femenino , Humanos , Persona de Mediana Edad , Procedimientos Quirúrgicos Mínimamente Invasivos , Complicaciones Posoperatorias , Incontinencia Urinaria de Esfuerzo/fisiopatología , Urodinámica , Procedimientos Quirúrgicos Urológicos
11.
Acta Med Croatica ; 49(4-5): 161-4, 1995.
Artículo en Inglés | MEDLINE | ID: mdl-8630446

RESUMEN

A prospective study was performed to determine whether the risk factor for hepatitis B, proposed by Centers for Disease Control (CDC), USA, are reliable predictors for the hepatitis B surface antigen (HBsAg) carrier state in an obstetric population. In the period between January 1, 1991 and December 31, 1992, all pregnant women from geographically defined areas of the Istrian and Rijeka districts were routinely screened for hepatitis B surface antigen (HBsAg). Among 10,627 pregnant women, 107 (1%) HBsAg positive cases were registered. History risk factors recommended by CDC were recorded in 46 (43%) out of 107 HBsAg positive women. The other 61 subjects had no recognizable risk factors. The screening of pregnant women for HBsAg only on the basis of the CDC recommended history guidelines, would have left 57% of our HBsAg positive mothers undetected and therefore their children unvaccinated against hepatitis B infection. Our results confirmed the need and value of the new CDC recommendations about routine prenatal screening of all pregnant women for HBsAg until hepatitis B vaccine is included in the scheme of compulsory vaccination of all newborns.


Asunto(s)
Antígenos de Superficie de la Hepatitis B/análisis , Hepatitis B/diagnóstico , Complicaciones Infecciosas del Embarazo/diagnóstico , Portador Sano/diagnóstico , Femenino , Hepatitis B/prevención & control , Hepatitis B/transmisión , Humanos , Transmisión Vertical de Enfermedad Infecciosa/prevención & control , Tamizaje Masivo , Embarazo , Estudios Prospectivos , Factores de Riesgo
12.
Zentralbl Gynakol ; 115(1): 33-5, 1993.
Artículo en Inglés | MEDLINE | ID: mdl-8438629

RESUMEN

Total of 321 preterm/term newborns delivered in normal singleton vaginal deliveries was studied. Babies were divided into two groups. The first one includes 62 newborns with single, isolated clinical sign: stinking amniotic fluid or intrapartal maternal febrility > or = 38 degrees C or duration of delivery > 12 hours. The second one (control group) contained 259 newborns with no such a sign. In both groups the umbilical cord blood IgG, IgM and IgA concentration (g/L) were quantified by a radial immunodiffusion method. The obtained values were classified into the groups according to 500-grams-birth-weight-ranges. The differences of the mean IgG, IgM and IgA concentrations between the each 500-grams-birth-weight-range subgroup separately in both control and experimental group so as between the same subgroup of the control and experimental group were tested by the means of the Student's t-test. Obtained results did not express the significant differences in the mean IgG, IgM and IgA umbilical cord blood concentrations between the experimental and control group of the newborns.


Asunto(s)
Corioamnionitis/inmunología , Sangre Fetal/inmunología , Inmunoglobulina A/análisis , Inmunoglobulina G/análisis , Inmunoglobulina M/análisis , Complicaciones del Trabajo de Parto/inmunología , Peso al Nacer , Corioamnionitis/diagnóstico , Femenino , Fiebre de Origen Desconocido/inmunología , Humanos , Recién Nacido , Complicaciones del Trabajo de Parto/diagnóstico , Trabajo de Parto Prematuro/inmunología , Embarazo , Valores de Referencia
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...