RESUMO
The catalytic electro-oxidation of some small organic molecules is known to display kinetic instabilities, which reflect on potential and/or current oscillations. Under oscillatory conditions, those systems can be considered electrocatalytic oscillators and, therefore, can be described by their amplitude, frequency, and waveform. Just like mechanical oscillators, the electrocatalytic ones can be coupled and their dynamics can be changed by setting different coupling parameters. In the present work, we study the unidirectional coupling of electrocatalytic oscillators, namely, those comprehending the catalytic electro-oxidation of methanol and formic acid on polycrystalline platinum in acidic media under potentiostatic control. Herein, we explore two different scenarios (the coupling of compositionally identical and non-identical oscillators) and investigate the effects of the master's identity and of the coupling constant on the slave's dynamics. For the master (methanol)-slave (methanol) coupling, the oscillators exhibited phase lag synchronization and complete phase synchronization. On the other hand, for the master (formic acid)-slave (methanol) coupling, the oscillators exhibited complete phase synchronization with phase-locking with a 2:3 ratio, complete phase synchronization with phase-locking with a 1:2 ratio, phase lag synchronization, and complete phase synchronization. The obtained results suggest that both the master's identity and the coupling constant (sign and magnitude) are parameters that play an important role on the coupled systems, in such a way that even for completely different systems, synchronization could emerge by setting a suitable coupling constant. To the best of our knowledge, this is the first report concerning the electrical coupling of hidden N-shaped-negative differential resistance type systems.
RESUMO
Previously, our group reported the establishment of a white callus cell line of Buddleja cordata Kunth that is a high producer of the secondary metabolite, verbascoside (VB, also named acteoside), under suspension culture conditions. Here, we present experimental evidence of the sustained ability of that cellular line to grow and produce high amounts of VB for 5 years of continuous culture. Cellular line profiles were determined at the early (at the beginning) and late stages (at the end of 5 years of continuous subculturing) by analyzing relevant parameters of culture growth, i.e., specific growth rate [µ], doubling time [dt], and growth index [GI], as well as VB production. Late-stage cultures exhibited a 61% faster growth rate than early-stage subcultures, and 25 and 3% lower doubling time and growth index. The extents of growth phases were found to be different. Similar amounts of biomass were found (9.5 g and 9.4 g L-1). Verbascoside production increased parallel to cell growth; maximal yield level occurred in the mid-exponential phase and lasted until the end of the stationary phase (i.e., from the 15th to the 25th day and from the 9th to the 21st day for the early and late stages, correspondingly). The content of VB was higher in the late-stage culture (1.43 ± 0945 g L-1) than in the early-stage culture (1.21 ± 0.0286 g L-1). Productivity values point out the potential use of B. cordata cell line in the biotechnological production of VB and for research focused on the biochemistry of secondary metabolism.
RESUMO
In the course of (electro)catalytic reactions, reversible and irreversible changes, namely the formation of adsorbed poisons, catalyst degradation, surface roughening, etc., take place at distinct time-scales. Reading the transformations on the catalyst surface from the measurement of the reaction rates is greatly desirable but generally not feasible. Herein, we study the effect of random surface defects on Pt(100) electrodes toward the electro-oxidation of methanol in acidic media. The surface defects are gently generated in situ and their relative magnitudes are reproducibly controlled. The system was characterized under conventional conditions and investigated under an oscillatory regime. Oscillatory patterns were selected according to the presence of surface defects, and a continuous transition from large amplitude/low frequency oscillations (type L) on smooth surfaces to small amplitude/high frequency oscillations (type S) on disordered surfaces was observed. Importantly, self-organized potential oscillations were found to be much more sensitive to the surface structure than conventional electrochemical signatures or even other in situ characterization methods. As a consequence, we proved the possibility of following the surface fine structure in situ and in a non-invasive manner by monitoring the temporal evolution of oscillatory patterns. From a mechanistic point of view, we describe the role played by surface defects and of the adsorbed and partially oxidized, dissolved species on the oscillations of type S and L.
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La encefalopatía traumática crónica (ETC) es una enfermedad neurodegenerativa que se produce como consecuencia traumatismos cerebrales repetitivos; concusiones, que son un síndrome clínico que se caracteriza por una alteración de la función cerebral. Una concusión, bajo su estricta definición, no debiese causar cambios estructurales en el cerebro por lo que no sería visible a través de imágenes, sí existen cambios a nivel microscópicos, bioquímicos y biomecánicos. La mayoría de los pacientes tienen completa resolución de sus síntomas dentro de 10 días (90 por ciento), pero existe un pequeño porcentaje que persiste con estos, pudiendo presentarse como un síndrome postconcusional, síndrome de segundo impacto o una encefalopatía traumática crónica. La ETC se caracteriza por la acumulación de prot-tau hiperfosforilada en neuronas y astrocitos. Estas se van a presentar en forma de ovillos o hilos neurofibrilares. En etapas iniciales las encontraremos de forma focalizada en la corteza frontal y en las formas más severas su distribución será más generalizada, distribuyéndose en la mayoría de las regiones del cerebro. Su diagnóstico se realiza a través de histopatología, por lo que hasta el momento sólo se ha logrado post-mortem. Se está trabajando en nuevas tecnologías asociadas a biomarcadores y PET para lograr una diagnostico premortem. El mayor énfasis en el manejo de esta taupatía es la prevención y adecuado manejo de las concusiones.
Chronic Traumatic Encephalopathy (CTE) is a neurodegenerative disease which is produced as a consequence of repeated brain trauma: concussions, which are a clinical syndrome characterized by an alteration in brain functions. A concussion, understrict definition, should not cause structural changes to the brain. Therefore, it would not be possible to see through images if there were changes at a microscopic, biochemical level. Most patients see their symptoms completely resolved within 10 days (90 percent), but there is a small percentage which persists, and these might cause a post-concussional syndrome, second impact syndrome of chronic traumatic encephalopathy. CTE is characterized by the accumulation of hyper-phosphorylated Tau protein in neurons and astrocytes. These appear in the form of neurofibrillary tangles. During the initial stages they are focalized in the frontal cortex and, in more severe cases, their distribution is more generalized, spreading through the majority of the regions in the brain. It is diagnosis is done through histopathology. Thus, it has only been possible to do post mortem. New technologies associated with bio-markers and PET are being worked on to achieve a pre-mortem diagnosis. The greatest emphasis in the handling of this tauopathy lies in the prevention and the adequate handling of concussions.
Assuntos
Humanos , Concussão Encefálica/complicações , Encefalopatia Traumática Crônica/diagnóstico , Encefalopatia Traumática Crônica/etiologia , Encefalopatia Traumática Crônica/prevenção & controle , Proteínas tau , Tauopatias , Dano Encefálico Crônico , Cadáver , Dano Encefálico Crônico/complicações , Doenças NeurodegenerativasRESUMO
Fundamento: Los meningiomas son tumores originados de las cubiertas aracnoideas. La localización intraventricular es rara especialmente los originados en el trígono ventricular derecho. Objetivo: Reportar un caso de localización atípica de un meningioma intracraneal. Presentación de caso: Paciente femenina de 68 años con historia de crisis convulsivas focales y cefalea de un mes de evolución. Las imágenes de Resonancia Nuclear Magnética convencionales, con secuencias en T1 y T2 axial y sagital, muestran una lesión localizada en el trígono ventricular derecho. Se realizó abordaje quirúrgico directo y excéresis total. El estudio anatomopatológico demostró un Meningioma fibroblástico. Discusión: Los meningiomas intraventriculares a nivel de trígono son infrecuentes y sólo se reportan series de pocos pacientes en la literatura. El abordaje y excéresis quirúrgica es el método de tratamiento de elección. Conclusiones: El abordaje y excéresis de meningiomas intraventriculares puede ser llevado a cabo exitosamente y en ausencia de complicaciones importantes.
Fundaments: Intraventricular meningiomas are rare often histologically benign tumors, especially those arisingfrom the right ventricular trigonal region. Objective: Report an unusual growth of intracranial meningioma. Case report: Authors present a clinical case of a 68 years old female with focal crisis and cephalea. Magnetic Resonance Imaging showed globular small hypo intense mass located in the right trigone. Surgical approach consisted in parietal craniotomy followed by dural opening and resection of the Intraventricular tumor. Post operatory evolution was adequate. Histological diagnosis was fibroblastic meningioma. Discussion: Meningiomas of the right lateral ventricule are rare and not widely reported. Surgical treatment is often successfully performed. Conclusion: Meningiomas of the lateral ventricles can be successfully diagnosed and surgically treated.
Assuntos
Humanos , Feminino , Idoso , Ventrículos Laterais , Meningioma , NeoplasiasRESUMO
Se realizó un estudio descriptivo observacional de todos los pacientes diagnosticados de meningiomas Intracraneales en el Servicio de Neurocirugía del Hospital provincial Docente "Manuel Ascunce Domenech". Se determinó que los meningiomas Intracraneales resultaron más frecuentes en mujeres de la cuarta y quinta décadas de la vida, la cefalea, el déficit motor y las alteraciones mentales fueron los signos y síntomas neurológicos de mayor incidencia. La localización más frecuente de la lesión fue la de la convexidad frontal y resultó ser la de mejor grado de resección quirúrgica. El meningioma meningotelial, seguido del psamomatoso fueron los tipos histológicos predominante y las complicaciones respiratorias, la fístula de LCR y la sepsis quirúrgica ocuparon el primer lugar en cuanto a complicaciones. Se discuten y comparan estos resultados con la literatura nacional e internacional.
A descriptive observational study was run on all patients with intracranial meningiomas diagnosis at the Neurosurgery Department of the Academic Hospital "Manuel Ascunce Domenech". The result was that intracranial meningiomas are more frequent in women in their forties and fifties, migraine, motor deficit and mental disturbances were the neurological signs and symptoms of main incidence. The most frequent location of the lesion was the frontal convexity and proved to be of the best level of surgical resection. The meningiothelial meningioma followed by the psammomatous were the predominant histological types as well as the respiratory complications. As for complications the CSV fistula and surgical sepsis were on the first place. These results are discussed and compared with national and international literature.
Assuntos
Humanos , Masculino , Adulto , Feminino , Pessoa de Meia-Idade , Meningioma/cirurgia , Meningioma/patologia , Neoplasias Meníngeas/cirurgia , Neoplasias Meníngeas/patologia , Distribuição por Idade e Sexo , Cuba/epidemiologia , Meningioma/epidemiologia , Neoplasias Meníngeas/epidemiologia , Complicações Pós-Operatórias , Procedimentos Neurocirúrgicos/estatística & dados numéricosRESUMO
In a search for microorganisms producing extracellular protease with unhairing activity, Bacillus subtilis IIQDB32 was isolated. Protease formation was significantly stimulated by glucose, tryptone, yeast extract, Ca(2+) and Mn(2+), but was repressed by ammonia and Fe(2+).
RESUMO
Antofagasta, the big city-port in North Chile is a triatomines free locality. Chagas infection was serologically diagnosed in 44 out of 2063 (2.1%) pregnant women from Antofagasta, studied by means of an indirect immunoflourescence test (IIFT), during 1991-1993. Out of the 44 seropositive mothers, 31 and 10 were born in the II (moderate endemic area) and IV Región (hiperendemic area), respectively. The usefulness of a screening programme for congenital Chagas' disease at primary health care in Chile is discussed.
Assuntos
Doença de Chagas/epidemiologia , Complicações Parasitárias na Gravidez/epidemiologia , Adolescente , Adulto , Chile/epidemiologia , Feminino , Humanos , Recém-Nascido , Gravidez , Prevalência , Estudos SoroepidemiológicosRESUMO
A randomized clinical trial was completed to compare the efficacy of a mixed diet composed of locally available foods versus a lactose-free, soy-based formula for the management of young Mexican children with acute diarrhea and dehydration. A total of 87 patients between 5 and 36 months of age received either a blended mixed diet containing rice, chicken, carrots, beans, and vegetable oil (group MD) or a soy formula (group SF) immediately after standard oral rehydration therapy. The initial clinical characteristics of the patients in each group were similar, as were their stool outputs during the first 6-hour period of rehydration before the diets were offered. There were six treatment failures, all of which were in group SF (p < 0.01). The stool outputs of children in group MD and in group SF were 82 +/- 55 versus 112 +/- 88 gm/kg per day, respectively, on day 1 (p = 0.037), and 48 +/- 33 versus 66 +/- 55 gm/kg per day on day 2 (p = 0.109). The duration of diarrhea among those in group MD was significantly reduced compared with those in group SF (29 vs 67 hours; p < 0.001). We conclude that the mixed diet resulted in improved clinical outcomes compared with the lactose-free, soy protein isolate formula.
Assuntos
Diarreia/dietoterapia , Proteínas Alimentares/administração & dosagem , Hidratação , Alimentos Fortificados , Glycine max , Alimentos Infantis , Oryza , Administração Oral , Peso Corporal , Pré-Escolar , Terapia Combinada , Diarreia/microbiologia , Diarreia/fisiopatologia , Diarreia/terapia , Diarreia Infantil/dietoterapia , Diarreia Infantil/microbiologia , Diarreia Infantil/fisiopatologia , Diarreia Infantil/terapia , Humanos , Lactente , Masculino , Soluções para Reidratação/uso terapêutico , Índice de Gravidade de Doença , Fatores de Tempo , Aumento de PesoRESUMO
The substitution of chemical depilatory agents in the leather industry by proteolytic enzymes produced by Bacillus species has an important economical and environmental impact. In previous assays, a Bacillus sp. showing a promising depilatory activity was isolated. In this paper, a culture medium that stimulated the synthesis and segregation of depilatory proteases, was selected. The influence of pH, oxygen supply rate (KLaC*), and inoculum age was evaluated on cell growth and protease production. Assays were carried out in lab bioreactors (1.2-1.4 l) at 37 degrees C. Five different media that differed in carbon and nitrogen sources were tested. pH ranged from 4.0 to 8.5. KLaC* varied between 40 and 470 mmol/lh. The best medium culture for protease production contained: nutrient broth (Britania) 8 g/l, yeast extract (Britania) 3 g/l, and mineral salts. Protease production was more effective at pH of 6.7, KLaC* of 360 mmol/lh, and inoculum age of 12 hours. These experimental conditions led to the following results: maximum proteolytic activity 2700 U/ml, overall volumetric protease productivity 300 u/ml-h, average specific growth rate 0.62 h-1, and average specific protease production rate 2.50 x 10(5) U/gh.
Assuntos
Bacillus/enzimologia , Proteínas de Bactérias/isolamento & purificação , Endopeptidases/isolamento & purificação , Remoção de Cabelo/métodos , Microbiologia Industrial , Bacillus/efeitos dos fármacos , Bacillus/crescimento & desenvolvimento , Proteínas de Bactérias/biossíntese , Proteínas de Bactérias/genética , Carbono/metabolismo , Meios de Cultura/farmacologia , Endopeptidases/biossíntese , Endopeptidases/genética , Indução Enzimática/efeitos dos fármacos , Concentração de Íons de Hidrogênio , Nitrogênio/metabolismo , Oxigênio/metabolismoRESUMO
The safety and efficacy of a rice-based oral rehydration salt (ORS) solution for the treatment of acute diarrhea in infants < 6 months of age was compared to those of a standard glucose-based ORS solution. A total of 97 infants aged 1-6 months who had a history of acute diarrhea for 120 h or less and showed signs of mild to moderate dehydration and no complications was recruited. Subjects were assigned to two treatment groups and received either standard glucose-based ORS solution or rice-based ORS solution until cessation of diarrhea. There was no significant difference between the two treatment groups with regard to the main outcome variables, including total stool output (84 [95% confidence interval (CI), 56-126] vs. 106 (95% CI, 76-148) g/kg], total ORS solution intake [171 (95% CI, 149-197) vs. 187 (95% CI, 161-218) ml/kg], or duration of diarrhea (35 +/- 31 vs 38 +/- 32 h). In addition, the fact that there was no difference between treatment groups in the presence of reducing substances in the stools suggests that rice was digested and absorbed by these infants. The results of our study support the conclusion that for infants < 6 months of age, rice-based ORS solution is safe and as efficacious as standard glucose-based ORS solution in the treatment of acute diarrhea.
Assuntos
Diarreia/terapia , Oryza , Soluções para Reidratação/uso terapêutico , Doença Aguda , Hidratação , Glucose , Humanos , Lactente , Recém-Nascido , Masculino , MéxicoRESUMO
The substitution of chemical depilatory agents in the leather industry by proteolytic enzymes produced by Bacillus species has an important economical and environmental impact. In previous assays, a Bacillus sp. showing a promising depilatory activity was isolated. In this paper, a culture medium that stimulated the synthesis and segregation of depilatory proteases, was selected. The influence of pH, oxygen supply rate (KLaC*), and inoculum age was evaluated on cell growth and protease production. Assays were carried out in lab bioreactors (1.2-1.4 l) at 37 degrees C. Five different media that differed in carbon and nitrogen sources were tested. pH ranged from 4.0 to 8.5. KLaC* varied between 40 and 470 mmol/lh. The best medium culture for protease production contained: nutrient broth (Britania) 8 g/l, yeast extract (Britania) 3 g/l, and mineral salts. Protease production was more effective at pH of 6.7, KLaC* of 360 mmol/lh, and inoculum age of 12 hours. These experimental conditions led to the following results: maximum proteolytic activity 2700 U/ml, overall volumetric protease productivity 300 u/ml-h, average specific growth rate 0.62 h-1, and average specific protease production rate 2.50 x 10(5) U/gh.
RESUMO
The substitution of chemical depilatory agents in the leather industry by proteolytic enzymes produced by Bacillus species has an important economical and environmental impact. In previous assays, a Bacillus sp. showing a promising depilatory activity was isolated. In this paper, a culture medium that stimulated the synthesis and segregation of depilatory proteases, was selected. The influence of pH, oxygen supply rate (KLaC*), and inoculum age was evaluated on cell growth and protease production. Assays were carried out in lab bioreactors (1.2-1.4 l) at 37 degrees C. Five different media that differed in carbon and nitrogen sources were tested. pH ranged from 4.0 to 8.5. KLaC* varied between 40 and 470 mmol/lh. The best medium culture for protease production contained: nutrient broth (Britania) 8 g/l, yeast extract (Britania) 3 g/l, and mineral salts. Protease production was more effective at pH of 6.7, KLaC* of 360 mmol/lh, and inoculum age of 12 hours. These experimental conditions led to the following results: maximum proteolytic activity 2700 U/ml, overall volumetric protease productivity 300 u/ml-h, average specific growth rate 0.62 h-1, and average specific protease production rate 2.50 x 10(5) U/gh.
RESUMO
In this paper, the influence of aeration rate on the alcoholic batch fermentation of whey by Kluyveromyces fragilis NRRL Y-2415 was investigated. Assays in 1.5-L fermentor using concentrated whey permeate containing 100 g/L of lactose were carried out at different oxygen supply rate (KLaC*) from 0 to 82 mmol/Lh. Optimum response was obtained at 14 mmol/Lh: ethanol production rate reached was 3.4 g/Lh yielding 0.46 g of product per gram of initial lactose. An increase of KLaC* from 0 to 14 mmol/Lh improved the ethanol production: maximum specific ethanol production rate (qpm) increased 3.3 times from 0.3 to 1.0 g/gh. For higher aeration levels, ethanol production diminished and biomass formation was stimulated. The declination of qpm and the increase of microns at higher aeration level lead to conclude the importance of a controlled oxygen supply in order to obtain the required balance between yeast biosynthetic needs and ethanol production.