Multi-walled carbon nanotubes functionalized with a new Schiff base containing phenylboronic acid residues: application to the development of a bienzymatic glucose biosensor using a response surface methodology approach.

An innovative supramolecular architecture is reported for bienzymatic glucose biosensing based on the use of a nanohybrid made of multi-walled carbon nanotubes (MWCNTs) non-covalently functionalized with a Schiff base modified with two phenylboronic acid residues (SB-dBA) as platform for the site-specific immobilization of the glycoproteins glucose oxidase (GOx) and horseradish peroxidase (HRP). The analytical signal was obtained from amperometric experiments at - 0.050 V in the presence of 5.0 × 10-4 M hydroquinone as redox mediator. The concentration of GOx and HRP and the interaction time between the enzymes and the nanohybrid MWCNT-SB-dBA deposited at glassy carbon electrodes (GCEs) were optimized through a central composite design (CCD)/response surface methodology (RSM). The optimal concentrations of GOx and HRP were 3.0 mg mL-1 and 1.50 mg mL-1, respectively, while the optimum interaction time was 3.0 min. The bienzymatic biosensor presented a sensitivity of (24 ± 2) × 102 µA dL mg-1 ((44 ± 4) × 102 µA M-1), a linear range between 0.06 mg dL-1 and 21.6 mg dL-1 (3.1 µM-1.2 mM) (R2 = 0.9991), and detection and quantification limits of 0.02 mg dL-1 (1.0 µM) and 0.06 mg dL-1 (3.1 µM), respectively. The reproducibility for five sensors prepared with the same MWCNT-SB-dBA nanohybrid was 6.3%, while the reproducibility for sensors prepared with five different nanohybrids and five electrodes each was 7.9%. The GCE/MWCNT-SB-dBA/GOx-HRP was successfully used for the quantification of glucose in artificial human urine and commercial human serum samples.

Development of an electrochemical sensor for the quantification of ascorbic acid and acetaminophen in pharmaceutical samples.

This work presents the modification of glassy carbon electrodes (GCE) by using a dispersion resulting from the non-covalent functionalization of multi-walled carbon nanotubes (MWCNT) with polyarginine (polyArg). MWCNT-polyArg is used for the quantification of ascorbic acid (AA) in the presence of acetaminophen (APAP) and viceversa. Since ascorbic acid and acetaminophen are strongly absorbed on GCE/MWCNT-polyArg, they can be detected in the presence of 4.0×10-5 M acetaminophen (and 3.0×10-5 M ascorbic acid) by using adsorptive stripping with media exchange and differential pulse voltammetry. Using water as the solvent for the MWCNT dispersion, the result was Z-potential of 0.053 ± 0.006 V. The developed sensor showed excellent specificity, sensitivity, stability and reproducibility compared to previously published sensors. The GCE/MWCNT-polyArg sensor shows a fast response time of ∼5 minutes, low limits of detection and quantification for AA (0.95 and 2.9 µM respectively) and APAP (0.27 and 0.82µM, respectively), high sensitivity of 0.0616 µA/M for AA or APAP 0.240µA/M. It was used to test its practicability by determining the concentration of AA or APAP (AA and APAP) in pharmaceutical samples. Finally, the simultaneous measurement of ascorbic acid and acetaminophen in pharmaceuticals showed a good correlation, with a maximum error and RSD of 4.5 and 5.1 %, respectively.

L-Lactate Electrochemical Biosensor Based on an Integrated Supramolecular Architecture of Multiwalled Carbon Nanotubes Functionalized with Avidin and a Recombinant Biotinylated Lactate Oxidase.

L-Lactate is an important bioanalyte in the food industry, biotechnology, and human healthcare. In this work, we report the development of a new L-lactate electrochemical biosensor based on the use of multiwalled carbon nanotubes non-covalently functionalized with avidin (MWCNT-Av) deposited at glassy carbon electrodes (GCEs) as anchoring sites for the bioaffinity-based immobilization of a new recombinant biotinylated lactate oxidase (bLOx) produced in Escherichia coli through in vivo biotinylation. The specific binding of MWCNT-Av to bLOx was characterized by amperometry, surface plasmon resonance (SPR), and electrochemical impedance spectroscopy (EIS). The amperometric detection of L-lactate was performed at -0.100 V, with a linear range between 100 and 700 µM, a detection limit of 33 µM, and a quantification limit of 100 µM. The proposed biosensor (GCE/MWCNT-Av/bLOx) showed a reproducibility of 6.0% and it was successfully used for determining L-lactate in food and enriched serum samples.

Angiotensin II involvement in the development and persistence of amphetamine-induced sensitization: Striatal dopamine reuptake implications.

Amphetamine (AMPH) exposure induces behavioural and neurochemical sensitization observed in rodents as hyperlocomotion and increased dopamine release in response to a subsequent dose. Brain Angiotensin II modulates dopaminergic neurotransmission through its AT1 receptors (AT1-R), positively regulating striatal dopamine synthesis and release. This work aims to evaluate the AT1-R role in the development and maintenance of AMPH-induced sensitization. Also, the AT1-R involvement in striatal dopamine reuptake was analysed. The sensitization protocol consisted of daily AMPH administration for 5 days and tested 21 days after withdrawal. An AT1-R antagonist, candesartan, was administered before or after AMPH exposure to evaluate the participation of AT1-R in the development and maintenance of sensitization, respectively. Sensitization was evaluated by locomotor activity and c-Fos immunostaining. Changes in dopamine reuptake kinetics were evaluated 1 day after AT1-R blockade withdrawal treatment, with or without the addition of AMPH in vitro. The social interaction test was performed as another behavioural output. Repeated AMPH exposure induced behavioural and neurochemical sensitization, which was prevented and reversed by candesartan. The AT1-R blockade increased the dopamine reuptake kinetics. Neither the AMPH administration nor the AT1-R blockade altered the performance of social interaction. Our results highlight the AT1-R's crucial role in AMPH sensitization. The enhancement of dopamine reuptake kinetics induced by the AT1-R blockade might attenuate the neuroadaptive changes that lead to AMPH sensitization and its self-perpetuation. Therefore, AT1-R is a prominent candidate as a target for pharmacological treatment of pathologies related to dopamine imbalance, including drug addiction and schizophrenia.

A new strategy to build electrochemical enzymatic biosensors using a nanohybrid material based on carbon nanotubes and a rationally designed schiff base containing boronic acid.

We report a nanohybrid material obtained by non-covalent functionalization of multi-walled carbon nanotubes (MWCNTs) with the new ligand (((1E,1'E)-(naphthalene-2,3-diylbis(azaneylylidene))bis(methaneylylidenedene)) bis(4-hydroxy-3,1-phenylene))diboronic acid (SB-dBA), rationally designed to mimic some recognition properties of biomolecules like concanavalin A, for the development of electrochemical biosensors based on the use of glycobiomolecules as biorecognition element. We present, as a proof-of-concept, a hydrogen peroxide biosensor obtained by anchoring horseradish peroxidase (HRP) at a glassy carbon electrode (GCE) modified with the nanohybrid prepared by sonication of 2.0 mg mL-1 MWCNTs and 0.50 mg mL-1 SB-dBA in N,N-dimethyl formamide (DMF) for 30 min. The hydrogen peroxide biosensing was performed at -0.050 V in the presence of 5.0 × 10-4 M hydroquinone. The analytical characteristics of the resulting biosensor are the following: linear range between 0.175 µM and 6.12 µM, detection limit of 58 nM, and reproducibility of 2.0 % using the same nanohybrid (6 biosensors), and 9.0 % using three different nanohybrids. The sensor was successfully used to quantify hydrogen peroxide in enriched milk and human blood serum samples and in a commercial disinfector.

Estratificación hemodinámica mediante ecocardiografía transtorácica en pacientes con infarto agudo de miocardio con segmento ST elevado / Hemodynamic stratification using transthoracic echocardiography in patients with ST segment elevation acute myocardial infarction

Objetivo: Evaluar la factibilidad de realizar una estratificación hemodinámica en pacientes con infarto agudo de miocardio con segmento ST elevado, mediante el uso de ecocardiografía transtorácica. Materiales y métodos: Estudio descriptivo, prospectivo y transversal que incorporó a 30 pacientes en ritmo sinusal con diagnóstico de infarto agudo de miocardio con ST elevado, ingresados a la unidad coronaria del Hospital Edgardo Rebagliati Martins. Se estimó: gasto cardíaco, presión de llenado de ventrículo izquierdo, resistencia vascular sistémica y resistencia vascular pulmonar. Resultados: La edad promedio fue 67 ± 10.6 años, predominio masculino (86.7%). La estimación del gasto cardiaco y la presión de llenado del ventrículo izquierdo fue posible en el 100% de los individuos. La resistencia vascular sistémica y resistencia vascular pulmonar pudieron ser estimadas en 29 (96.6%) y 28 (93.3%) pacientes, respectivamente. La estratificación hemodinámica fue: estadio I (normal): 18 pacientes (60%), estadio II (congestivo): 6 pacientes (20%), estadio III (hipovolemia, compromiso de VD): 5 pacientes (16.7%) y estadio IV (Choque): 1 paciente (3.3%). Conclusiones: Se concluye que es factible realizar la estratificación hemodinámica ecocardiográfica transtorácica en la población estudiada

Objective: To evaluate the feasibility of performing a hemodynamic stratification in patients with ST segment elevation acute myocardial infarction using transthoracic echocardiography. Materials and methods: A descriptive, prospective and cross-sectional study that included 30 patients in sinus rhythm with ST segment elevation acute myocardial infarction, admitted to the coronary care unit of Hospital Edgardo Rebagliati Martins. Cardiac output, left ventricle filling pressure, systemic vascular resistance and pulmonary vascular resistance were estimated. Results: The mean age was 67 ± 10.6 years old, with male predominance (86.7%). The estimation of cardiac output and left ventricle filling pressure was possible in 100% of the individuals. The systemic vascular resistance and pulmonary vascular resistance could be estimated in 29 (96.6%) and 28 (93.3%) patients, respectively. The hemodynamic stratification was as follows: stage I (normal): 18 patients (60%), stage II (congestive): 6 patients (20%), stage III (hypovolemia, RV infarction): 5 patients (16.7%) and stage IV (shock): 1 patient (3.3%). Conclusions: It is concluded that a transthoracic echocardiographic hemodynamic stratification may be performed in the studied population

Circadian clock of Aedes aegypti: effects of blood-feeding, insemination and RNA interference

Mosquitoes are the culprits of some of the most important vector borne diseases. A species’ potential as a vector is directly dependent on their pattern of behaviour, which is known to change according to the female’s physiological status such as whether the female is virgin/mated and unfed/blood-fed. However, the molecular mechanism triggered by and/or responsible for such modulations in behaviour is poorly understood. Clock genes are known to be responsible for the control of circadian behaviour in several species. Here we investigate the impact mating and blood-feeding have upon the expression of these genes in the mosquito Aedes aegypti . We show that blood intake, but not insemination, is responsible for the down-regulation of clock genes. Using RNA interference, we observe a slight reduction in the evening activity peak in the fourth day after dstim injection. These data suggest that, as in Drosophila , clock gene expression, circadian behaviour and environmental light regimens are interconnected in Ae. aegypti .

Análise comparativa dos ritmos de atividade locomotora e expressão circadiana de Aedes aegypti e Culex quinquefasciatus / Comparative analysis of the rhythms of locomotor activity and circadian expression of Aedes aegypti and Culex quinquefasciatus

A grande maioria dos seres vivos complexos apresenta um relógio endógeno, conhecido como relógio circadiano, responsável por dirigir as oscilações rítmicas de fisiologia e comportamento dentro de um período de aproximadamente 24 horas. Em insetos, as bases genéticas deste marcapasso têm sido elucidadas em Drosophila melanogaster. Diversos loci já foram identificados e o mecanismo molecular regulando o relógio circaiano consiste de alças regulatórias interligadas que controlam a expressão rítmica de muitos genes. Muitas espécies de mosquitos são vetores de doenças. Elas exibem um variedade de padrões de atividade e hematofagia, de diurnos a crepusculares e noturnos e estes ritmos são importantes para a dinâmica da transmissão de doenças. Entretanto, apesar da sua importância epidemiológica, pouco se sabe quanto à genética molecular do relógio circadiano que controla seus ritmos de atividade. Nosso grupo tem estudado as bases moleculares do relógio circadiano em duas espécies de mosquitos, Aedes aegypti e Culex quinquefasciatus. Ambos são importantes vetores de doenças tropicais, mas com diferentes padrões de atividade. Ae. aegypti é o vetor diurno da Dengue e da Febre amarela, enquanto Cx. quinquefasciatus é o vetor noturno da Filariose e da Filariose e da Febre do Oeste do Nilo. Análises preliminares indicam uma conservação dos padrões de expressão entre as duas espécies em alguns dos mais importantes genes do relógio em claro-escuro e escuro constante. Entretanto, nós achamos diferenças na expressão do gene cryptochrome2 (cry2), um ortólogo dos genes codificando criptocromos de mamíferos e que foi encontrado em muitos insetos, mas que não está presente em Drosophila. Nós sugerimos que cry2 pode estar envolvido no controle dos padrões de atividade de Ae. aegypti e Cx. quinquefasciatus, e propusemos um modelo para explicar as diferenças na expressão de cry2. Nós também estudamos a expressão circadiana dos principais genes de relógio, além dos ritmos de atividade locomotora destas duas espécies em ciclos de temperatura. Observamos que ambas são arrastadas pela temperatura e mostram diferenças entre seus comportamentos de atividade. Em ciclos de temperatura, a atividade locomotora de Ae. aegypti é mais restrita a termofase, enquanto Cx. quinquefasciatus apresenta sua atividade mais restrita a criofase. Além disso, após o arrastamento em ciclos de claro-escuro, Ae. aegypti mostrou um padrão transiente de atividade por alguns dias em escuro constante com ciclos de temperatura, enquanto Cx. quinquefasciatus permaneceu estável nesta condição. Também foram observadas, em ciclos de temperatura, algumas diferenças espécies-específicas nos padrões de expressão de cycle e cry2. Finalmente, nós observamos diferenças na fase da expressão circadiana de Ae. aegypti em ciclos de temperatura e escuro constante entre mosquitos criados com uma combinação de ciclos de claro-escuro e de temperatura com mosquitos criados em ciclos de claro-escuro com temperatura constante. Isto sugere um importante papel do desenvolvimento na determinação dos padrões de expressão circadiana de insetos adultos submetidos a oscilações de temperatura.

Impacto de la educación antiparasitaria en la demanda de educación médica / Impact of antiparasitary education upon medical attention demand

Para evaluar el impacto de una estrategia de ducación antiparasitaria en la tasa de demanda de servicios por parasitosis intestinal, se midieron las consultas otorgadas en medicina familiar por parasitosis y las dosis de albendazol, un año antes y un año después de la eduación específica antiparasitaria. Se dieron 496 pláticas educativas dirigidas a escolares y madres. Asistieron en total 8945 personas. La tasa de consultas por parasitosis se redujo de 53 a 12 por 1000 derechohabientes (DH); y por ascaridiasis se redujo de 3.1 a 1.8 por 1000. Las dosis de albendazol se redujeron de 8503 a 3412. Se concluye que la educación específica antiparasitaria reduce la demanda de atención médica y la utilizació de albendazol. Se requiere en otro estudio comprobar el impacto sobr el resultado coproparasitoscópico

Incidencia de cólera en Ciudad Lázaro Cárdenas, Michoacán (1992) / Incidence of cholera at Lazaro Cardenas, Michoacan (1992)

Para determinar la incidencia, distribución por grupos de edad, los síntomas y signos de un brote de cólera ocurrido en Ciudad Lázaro Cárdenas, Mich., en el año de 1992, se diseñó un estudio retrospectivo y descriptivo. Durante las semanas epidemiológicas 28 a 53, se registraron 5202 casos de gastroenteritis, con una incidencia de 76.37 por 1000 habitantes, de los cuales 178 correspondieron a cólera, con una tasa de ataque de 2.52 por 100 pacientes y una tasa de letalidad de 22.43 por 1000 pacientes (cuatro defunciones) y tasa de mortalidad específica de 0.56 por 1000 pacientes. El grupo de edad más afectado fue el de 25 a 44 años. El cuadro clínico fue similar al descrito en los textos clásicos. En la situación epidemiológica presentada, la tasa de morbimortalidad es significativa y superior a las tasas estatales y nacionales. Las manifestaciones clínicas no difieren a lo informado en la literatura