Electrostrictive and piezoelectrical properties of chitosan-poly(3-hydroxybutyrate) blend films.

Herein, we report the high apparent piezoelectric coefficient for chitosan-poly(3-hydroxybutyrate) (CS-PHB) blend films. The structure of chitosan-poly(3-hydroxybutyrate) (CS-PHB) blend films, exploiting characteristics such as dielectric, polarization, apparent piezoelectric properties, and their dependencies on the composition, were investigated. Based on the results of XRD, SEM, FTIR, PFM, and dielectric spectroscopy measurements, the structure of CS-PHB blend films has been proposed, which consists of spheric-like inclusion formed by precipitating isotactic-PHB interface layer, which consists of syndiotactic-PHB hydrogen bonding with CS, and CS matrix. The synergistic effects of piezoelectricity and electrostriction help explain the high value of the apparent piezoelectric coefficient (d33) obtained in the blend film with 13 wt% of PHB (d33 ≈ 200 pC/N). The investigated CS-PHB blend films are a good candidate for tissue engineering applications.

Simultaneous Generation of Surface Plasmon and Lossy Mode Resonances in the Same Planar Platform.

A planar waveguide consisting of a coverslip for a microscope glass slide was deposited in one of its two faces with two materials: silver and indium tin oxide (ITO). The incidence of light by the edge of the coverslip permitted the generation of both surface plasmon and lossy mode resonances (SPRs and LMRs) in the same transmission spectrum with a single optical source and detector. This proves the ability of this optical platform to be used as a benchmark for comparing different optical phenomena generated by both metal and dielectric materials, which can be used to progress in the assessment of different sensing technologies. Here the SPR and the LMR were compared in terms of sensitivity to refractive index and figure of merit (FoM), at the same time it was demonstrated that both resonances can operate independently when silver and ITO coated regions are surrounded by different refractive index liquids. The results were supported with numerical results that confirm the experimental ones.

Clinical Factors Associated with High Glycemic Variability Defined by Coefficient of Variation in Patients with Type 2 Diabetes.

BACKGROUND: High glycemic Variability (HGV) has become a stronger predictor of hypoglycemia. However, clinical factors associate with HGV still are unknown. OBJECTIVE: To determine clinical variables that were associated with a coefficient of variation (CV) above 36% evaluated by continuous glucose monitoring (CGM) in a group of patients with diabetes mellitus. METHODS: A cohort of patients with type 2 diabetes (T2D) was evaluated. Demographic variables, HbA1c, glomerular filtration rate (GFR) and treatment regimen were assessed. A bivariate analysis was performed, to evaluate the association between the outcome variable (CV> 36%) and each of the independent variables. A multivariate model was constructed to evaluate associations after controlling for confounding variables. RESULTS: CGM data from 274 patients were analyzed. CV> 36% was present in 56 patients (20.4%). In the bivariate analysis, demographic and clinical variables were included, such as time since diagnosis, hypoglycemia history, A1c, GFR and treatment established. In the multivariate analysis, GFR <45 mL/min (OR 2.81; CI 1.27,6.23; p:0.01), A1c > 9% (OR 2.81; CI 1.05,7.51; p:0.04) and hypoglycemia history (OR 2.09; CI 1.02,4.32; p:0.04) were associated with HGV. Treatment with iDPP4 (OR 0.39; CI 0.19,0.82; p:0.01) and AGLP1 (OR 0.08; CI 0.01,0.68; p:0.02) was inversely associated with GV. CONCLUSION: Clinical variables such as GFR <45 mL/min, HbA1C>9% and a history of hypoglycemia are associated with a high GV. Our data suggest that the use of technology and treatments able to reduce glycemic variability could be useful in this population to reduce the risk of hypoglycemia and to improve glycemic control.

Selective synthesis of turbostratic polyhedral carbon nano-onions by arc discharge in water.

Carbon nano-onions (CNOs), in their spherical or polyhedral forms, represent an important class of nanomaterials, due to their peculiar physical and electrochemical properties. Among the different methods of production, arc discharge between graphite electrodes sustained by deionized water is one of the most promising to obtain good quality CNOs in gram quantities. We applied the method with the aim to optimize the production of CNOs, using an innovative experimental arrangement. The discharges generate dispersed nanomaterials and a black hard cathodic deposit, which were studied by transmission electron microscopy-high-resolution TEM, scanning electron microscopy, Raman, thermogravimetric analysis and energy-dispersive x-ray spectroscopy. A simple mechanical grinding of the deposits permitted us to obtain turbostratic polyhedral CNOs that exhibited higher stability towards burning in air, compared to CNOs found in water. We propose a mechanism for the formation of the CNOs present in the deposit, in which the crystallization is driven by a strong temperature gradient existing close to the cathode surface at the beginning of the process, and subsequently close to the deposit surface whenever it is growing.

Surface functionalized halloysite nanotubes decorated with silver nanoparticles for enzyme immobilization and biosensing.

Improving enzyme immobilization with high loading capacity and achieving direct electron transfer (DET) between the enzyme and the electrode surface is key to designing highly sensitive enzymatic electrochemical biosensors. Herein, we report a novel approach based on the selective modification of the outer surface of halloysite nanotubes (HNTs) that supports silver nanoparticles (AgNPs) to obtain a hybrid nanocomposite. AgNPs of about 10 nm average size could be uniformly supported on silane-modified HNTs through in situ reduction of Ag+ ions. The resultant nanocomposite shows an excellent support capability for the effective immobilization and electrical wiring of redox enzyme glucose oxidase (GOx). The GOx immobilized HNT/AgNPs were deposited on the glassy carbon electrode (GCE) and utilized for the bioelectrocatalyzed electrochemical detection of glucose. The GOx modified composite electrodes show glucose sensitivity as high as 5.1 µA mM-1 cm-2, which is higher than for the electrodes prepared without surface functionalization.

Computer controlled-flow injection potentiometric system based on virtual instrumentation for the monitoring of metal-biosorption processes.

A completely automated flow-injection system was developed for the monitoring of biosorption studies of Cu(II) ion on vegetable waste by-products. The system employed flow-through Cu(II)-selective electrodes, of epoxy-resin-CuS/Ag(2)S heterogeneous crystalline type, and computer controlled pumps and valves for the flow operation. Computer automation was done through a specially devised virtual instrument, which commanded and periodically calibrated the system, allowing for the monitoring of Cu(II) ions between 0.6 and 6530 mg L(-1) at a typical frequency of 15 h(-1). Grape stalk wastes were used as biosorbent to remove Cu(II) ions in a fixed-bed column with a sorption capacity of 5.46 mg g(-1), obtained by the developed flow system, while the reference determination performed by FAAS technique supplied a comparable value of 5.41 mg g(-1).

[Utility of chest x-ray like approach to etiology of community acquired pneumonia in children]. / Utilidad de la radiografía de tórax en niños como aproximación a la etiología de neumonía adquirida en la comunidad.

INTRODUCTION: Chest X-ray (CR) utility to predict etiology in community-acquired pneumonia (CAP), in children has been controversial. Nevertheless, some authors propose the use of well standardized radiological patterns. OBJECTIVE: To evaluate usefulness of modified Swischuk's radiological patterns (RaP) to determine probable etiology in children hospitalized with CAP. PATIENTS AND METHODS: Eighty children were studied using 6 standardized RaP. The RaP were blindly and individually analyzed by 9 pneumologists, who registered the results (stage 1). Thereafter, (stage 2) a second evaluation adding clinical information was performed. Then, the patients complementary examinations and clinical evolution were included (stage 3). The reference standard (RS) was generated from a blind consensus. Every result was compared with the RS using Student test. RESULTS: According to RS, children were classified as having a virus-like pneumonia in 63% of cases, bacterial in 13%, mixed in 16%, atypical in 5% and ADV in 3%. The agreement of stage 1 and 2 with RS was 64 and 77%, respectively. Virus and bacterial RaP agreement increased from 66 to 82 % (p < 0.001) and from 82 to 90% (p < 0.05), respectively after incorporating clinical parameters. CONCLUSION: Modified Swischuk's RaP used in association with clinical elements allows a quite satisfactory approach to etiologic diagnosis of CAP.

Utilidad de la radiografía de tórax en niños como aproximación a la etiología de neumonía adquirida en la comunidad / Utility of chest x-ray like approach to etiology of community acquired pneumonia in children

Introduction: Chest X-ray (CR) utility to predict etiology in community-acquired pneumonia (CAP), in children has been controversial. Nevertheless, some authors propose the use of well standardized radiological patterns. Objective: To evaluate usefulness of modified Swischuk's radiological patterns (RaP) to determine probable etiology in children hospitalized with CAP. Patients and Methods: Eighty children were studied using 6 standardized RaP. The RaP were blindly and individually analyzed by 9 pneumologists, who registered the results (stage 1). Thereafter, (stage 2) a second evaluation adding clinical information was performed. Then, the patients complementary examinations and clinical evolution were included (stage 3). The reference standard (RS) was generated from a blind consensus. Every result was compared with the RS using Student test. Results: According to RS, children were classified as having a virus-like pneumonia in 63 percent of cases, bacterial in 13 percent, mixed in 16 percent, atypical in 5 percent and ADV in 3 percent. The agreement of stage 1 and 2 with RS was 64 and 77 percent, respectively. Virus and bacterial RaP agreement increased from 66 to 82 percent (p < 0.001) and from 82 to 90 percent (p < 0.05), respectively after incorporating clinical parameters. Conclusion: Modified Swischuk's RaP used in association with clinical elements allows a quite satisfactory approach to etiologic diagnosis of CAP.

Introducción: La utilidad de la radiografía de tórax.(RT) para establecer etiología en niños con neumonía adquirida en la comunidad (NAC) es cuestionada. Objetivo: Evaluar la utilidad de los patrones radiológicos (PRa) de Swischuk modificados para determinar la probable etiología en niños hospitalizados con NAC. Pacientes y Método: Se estudió 80 niños mediante el uso de seis PRa estandarizados. Se procedió al análisis secuencial por nueve neumólogos; individualmente de manera ciega (etapa 1), se registró el PRa. Posteriormente (etapa 2) se agregó información clínica. En seguida se incluyó exámenes complementarios y la evolución de cada niño (etapa 3). El estándar de referencia (ER) fue generado mediante consenso ciego. Se comparó cada resultado con el ER mediante t de Student. Resultados: Según el ER, las etiologías identificadas fueron: viral (63 por ciento), bacteriana (13 por ciento), mixta (16 por ciento), atípica (5 por ciento) y ADV (3 por ciento). El rendimiento de la etapa 1 y 2 fue 64 y 77 por ciento>, respectivamente. El PRa viral y bacteriano aumentó de 66 a 82 por ciento> (p < 0,001) y de 82 a 90 por ciento (p < 0,05), respectivamente, luego de incorporar elementos clínicos. Conclusión: La utilización de PRa de Swischuk modificados, asociados a elementos clínicos, permitió un adecuado rendimiento como aproximación del diagnóstico etiológico en NAC

Nitrification activities in full-scale treatment plants with varying salt loads.

The effect of salt on the nitrification activity in full-scale wastewater treatment plants (WWTP) was investigated. Not only the activity of ammonia and nitrite oxidisers was measured, but also the nitrifying population was assessed (by Fluorescent In Situ Hybridisation)--in full-scale domestic and industrial WWTPs, operated under various salt levels. The results demonstrate a decline in the activity of ammonia and nitrite oxidisers with an increase in salt content: the domestic WWTP with the lowest salt level (0.13g Cl- l(-1)) had the highest specific activity of ammonia and nitrite oxidisers (4.3 and 2.4 mg N (gVSS)(-1) h(-1), respectively), while the lowest specific activities of ammonia and nitrite oxidisers (1.1 and 0.5 mg N (gVSS)(-1) h(-1)) were measured at the highest NaCl concentration (16g Cl- l(-1)). However, comparing the nitrification activity of different types of sludge developed under different operational conditions with the reported values was not directly possible. So we have used the activated sludge model (ASM) to translate the routine operational data into parameters to enable the calculation of the actual fraction of nitrifiers and consequently the actual specific activity of ammonia and nitrite oxidisers. Expressing the activity of ammonia oxidisers in terms of actual specific activity makes the results from pure cultures, enriched cultures, pilot scale and full scale WWTPs comparable. Moreover, these results confirm the behaviour of nitrifiers under salt stress and validate the results obtained from pure and enriched cultures to be extrapolated to full scale.

Bauhinia candicans stimulation of glucose uptake in isolated gastric glands of normal and diabetic rabbits.

A butanol extract of dried leaves of Bahuinia candicans showed, in vitro, a stimulatory effect of glucose uptake in isolated gastric glands of normal and alloxan-diabetic rabbits. The extract (0.001-0.07 mg/mg protein) produced a dose-dependent effect and was similar to the effect of insulin (1-100 nM). These findings suggest that the extract contains compound(s) that efficiently increase glucose transport at the basolateral side of isolated gastric glands.

Hypoglycemic activity of Bauhinia candicans in diabetic induced rabbits.

The effect of different fractions of methanolic extract of Bauhinia candicans leaves were investigated on experimentally-induced diabetic rabbits. The crude extracts (8 mg/kg) showed hypoglycemic activity along with a reduced urinary glucose excretion. Among the fractions, the highest activity was exhibited by the butanolic fraction (fraction III). Moreover, fraction III reduced plasma glucose level also in normal, as well as, glucose loaded rabbits. These results suggest that B. candicans increases the peripheral metabolism of glucose.

Flow injection analysis of cholic acids in pharmaceutical preparations using a polymeric membrane ISE as detector.

The results reported in this paper regard the setting up of a polymeric membrane ISE that is selective for cholic acids (CA) and able to work in a flow system, especially in flow injection analysis (FIA), based on the exchanger (tetrakisdecylammoniumcholate, TDACh), which has proved effective, is of very simple but suitable structure and is above all easy to synthesise starting from commercially available chemicals. A complete analytical characterisation of the sensor was performed working both in batch conditions and in FIA, using in the latter case a 'wall jet' type of flow cell. The response toward different bile acid sodium salts such as the CA, deoxycholic (DCA), chenodeoxycholic (CDCA), ursodeoxycholic (UDCA), taurocholic (TCA) sodium salts was checked. The application to the analysis of different commercial drugs by FIA was also performed to determine the UDCA or CDCA acid content of several pharmaceutical formulations. Lastly, a preliminary study is presented concerning the use of the investigated electrochemical sensor as high performance liquid chromatography (HPLC) detector.

Anomalías congénitas como causa de muerte en el primer año de vida: Chile 1996 / Congenital malformations as cause of death in infant: Chile 1996

Las malformaciones congénitas (MC) influyen en la mortalidad infantil (MI). Con el propósito de conocer la importancia de MC en la MI en Chile en 1996, en las Estadísticas Vitales, se revisa las causas de fallecimiento en menores de un año, según Clasificación Internacional de Enfermedades. Hubo una mortalidad infantil de 11,1 por mil, una mortalidad neonatal de 6,3 por mil, una mortalidad neonatal precoz 4,8 por mil. 30,6 por ciento fallecieron por MC, tasa de MI debida a MC es de 3,4 por mil. 50,2 por ciento fallecieron en la primera semana de vida y el 63,3 por ciento antes de 28 días. La mortalidad por MC no difiere por sexos (p > 0,05), la mortalidad es superior en varones en MC del aparato respiratorio y urinario p=0,049 y p=0,0072. Anencefalia, anomalías del aparato respiratorio, urinario, fallecen antes de los siete días de vida (P<0,001). MC más frecuentes: cardiovascular (28,7 por ciento), sistema nervioso (17,5 por ciento). El avance tecnológico ha reducido la MI, reducción adicional en la mortalidad neonatal dependerá del consejo genético y de la prevención de las malformaciones congénitas

Intestinal leiomyosarcoma as the cause of severe hemoperitoneum.

Leiomyosarcomas represent 10-20% of malignant tumors in the small bowel and 1% of those located in the large bowel. These tumors have aspecific symptoms depending on their size, location and histology. Intestinal leiomyosarcomas may be the cause of numerous types of surgical emergency. We report 2 cases of intestinal leiomyosarcoma in the jejunum and transverse colon. Both were diagnosed during an emergency exploratory celiotomy. The clinical features on admission were similar to those of acute abdomen. The main cause of surgical emergency was an extremely rare complication of gastrointestinal leiomyosarcoma: a severe hemoperitoneum. We briefly describe the surgical emergencies caused by intestinal leiomyosarcomas as well as the surgical methods employed in these cases.

[The effect of insecticide resistance on the demographic parameters of 3 strains of Culex quinquefasciatus (Diptera: Culicidae) under laboratory conditions]. / Efecto de la resistencia a los insecticidas sobre algunos parámetros demográficos de 3 cepas de Culex quinquefasciatus (Diptera: Culicidae), en condiciones de laboratorio.

The life tables of 3 strains of Culex quinquefasciatus were studied under laboratory conditions: Slab, susceptible to reference; Old Havana, treated with cypermethrin until its fourth generation; and Cotorro, from the field. It was found that the different levels of resistance to organophosphate insecticides and pyrethroids present in the Cotorro and Old Havana strains did not influence either on the duration of the period of development of the immature stages or in the sexual proportion of the emerged adults, but they had a favorable and directly proportional effect on the survival and longevity of the adults. However, they exerted a negative and inversely proportional influence on the reproduction and population growth of these strains. Useful data for the use and management of insecticides within the strategies of control of Culex quinquefasciatus, an important vector of lymphatic filariasis, are provided.

[The incidence of Culicidae in an urban area of Ciudad de La Habana during 1995]. / Incidencia de culícidos en una zona urbana de Ciudad de La Habana durante 1995.

In the present paper it is made an analysis of the incidence of culicides in the municipality of Marianao, Havana City, during 1995, after following the requirements of the National Program for the Eradication of Aedes aegypti. 6 species of mosquitoes were found in the municipality, with a predominance of the Culex quinquefasciatus and Aedes mediovittatus species. 4 focuses of Aedes aegypti were detected during this period. It was found that the groups of deposits preferred by the culicides for their breeding in this municipality were other deposits, low tanks, artificial deposits and larva traps. The People's Councils 4 and 5 (Libertad and Pogolotti) had the highest number of focuses (967 and 1,240, respectively, and therefore, they need more attention. It is analyzed the influence of the deficiencies of the public services, such as the collection of solid, wastes (garbage) and the existence of leakages and sewing overflows, on the proliferation of mosquitoes in the municipality.

[The effect of 2 diets on the biological aspects of Blattella germanica (Dictyoptera: Blattellidae) under laboratory conditions]. / Efecto de 2 dietas sobre aspectos biológicos de Blattella germanica (Dictyoptera: Blattellidae) en condiciones de laboratorio.

It was conducted a study of 2 colonies of Blattella germanica (Dictyoptera: Blattellidae) kept since 1994 in the laboratory at 29 +/- 1 degrees C, 70-75% of relative humidity and with different foods: one on a diet without proteins, consisting in portions of potatoes (Solanum tuberosum, L.), ripe banana (Musa paradisiaca, L.) and a sugary solution 10%, and the other with a protein content of 20.45% composed of pulverized and dry laboratory food for rats and a source of water. 6 nymphal stages were found with both types of food. There were determined the times of interchanges and the time of nymphal development, which were much shorter among the nymphs fed with proteins. The longevity of each sex showed no significant differences in connection with the type of food used. The times of appearance and eclosion of the oothecae of each oothecal cycle were determined with both foods. It was found that the females deposited up to 5 oothecae during their lives with the 2 types of diet. The average of nymphs per ootheca among the females fed with proteins was much greater (t = 5.33; p < 0.001). The results of this study show that when the food for B. germanica contains proteins, its nymphal development is faster and its reproductive capacity increases, which means that protein is a necessary nutrient for the diet of this species.

Diabetes and insulin-induced stimulation of L-arginine transport and nitric oxide synthesis in rabbit isolated gastric glands.

1. The properties of L-arginine transport have been characterized and correlated with cGMP production (index of nitric oxide (NO)) in whole gastric glands isolated from non-diabetic and alloxan-diabetic rabbits. 2. In non-diabetic and diabetic glands, transport of L-arginine was stereoselective, Na+ and pH independent and inhibited by other cationic amino acids. L-Arginine transport was slightly inhibited by L-leucine and L-phenylalanine, but unaffected by other neutral amino acids. 3. Diabetes enhanced the Vmax for saturable L-arginine transport from 10.7 +/- 1.0 to 17.7 +/- 0.5 pmol (mg protein)-1 s-1, with negligible changes in K(m). 4. Accumulation of the membrane potential-sensitive probe tetra[3H]phenylphosphonium (TPP+) was increased 2-fold in diabetic compared with non-diabetic gastric glands, suggesting a membrane hyperpolarization. 5. Basal intracellular cGMP levels were elevated 2-fold in diabetic gastric glands, and in non-diabetic glands histamine, vasoactive intestinal peptide, and bradykinin increased cGMP levels. The NO synthase inhibitor NG-nitro-L-arginine methyl ester (100 microM) abolished basal cGMP accumulation. 6. Addition of extracellular L-arginine induced a concentration-dependent increase in cGMP levels in gastric glands isolated from non-diabetic rabbits, but had no effect on elevated cGMP levels in diabetic glands. 7. Insulin induced a rapid (5 min) concentration-dependent increase in cGMP levels in non-diabetic gastric glands, but reduced elevated cGMP levels in diabetic gastric glands. 8. The present study has identified a specific transport system for L-arginine in gastric glands which resembles the classical system y+. Our findings also provide the first direct evidence that diabetes increases the basal activity of system y+ and NO synthase in gastric glands. The differential modulation of L-arginine transport by insulin and L-arginine identified in non-diabetic and diabetic glands, may be of importance in protecting the gastric mucosa from injuries associated with diabetes.

Time-dependent changes of serum gastrin and gastrin receptors in the rat oxyntic mucosa after proximal gastric vagotomy.

Proximal gastric vagotomy (PGV) is a first-choice approach for the surgical treatment of duodenal peptic ulcer. However, a high percentage of recidivism takes place after this surgical strategy. To study the possible involvement of gastrin in ulcer recidivism, serum gastrin levels and gastrin receptors in gastric mucosa were determined at several times after PGV in rats. Gastrin concentration was determined using a commercial radioimmunoassay kit and gastrin receptors were analyzed in oxyntic mucosa membrane preparations using 125I-labeled 15-Leu-gastrin-17 as label. Our results show a significant, time-dependent increase in serum gastrin concentration, reaching highest values at 12 weeks after PGV. Similarly, a significant increase in the number of gastrin receptors (Bmax) and in the dissociation constant (Kd) occurred from 1 to 12 weeks post-PGV. Since gastrin exerts a positive feedback effect on its receptors, the PGV-dependent increase in serum gastrin concentration explains the up-regulation of the gastrin receptors in the rat oxyntic mucosa. Furthermore, an increase in the number of gastrin receptors after vagotomy may be at least partially responsible for the recidivism in duodenal peptic ulcers after this surgical approach.

[Biological aspects of Blatella germanica (Dictyoptera: Blattellidae) in laboratory conditions]. / Observaciones sobre aspectos biológicos de Blattella germanica (Dictyoptera: Blattellidae) en condiciones de laboratorio.

In a study of Blatella germanica (L) 1767 (Dictyoptera: Blattellidae) carried out in laboratory conditions, 6 nymphal stages were found in a period of 114.71 days, at 29 +/- 1 degrees C and 80-90% of relative humidity. Times of appearence and eclosion of every ovipositted ootheca, as well as the offspring average of each one, were determined. Females ovipositted up to 5 oothecas during their life. The maximum average of eggs found per ootheca was 29.22. The average longevity of males was lower that that of females (77.23 and 98.40 days, respectively) (t = 2.21; p < 0.05).