The biomechanics of leaf oscillations during rainfall events.

Plants are dynamic systems during rainfall events. As raindrops splash on leaf surfaces, the momentum of the raindrop is transferred to the leaf, causing the leaf to oscillate. The emphasis of this review is on the general principles of leaf oscillation models after raindrop impact and the ecological importance. Various leaf oscillation models and the underlying physical properties from biomechanics theory are highlighted. Additionally, we review experimental methods to derive the model parameters for and explore advances in our understanding of the raindrop-leaf impact process.

Surgical Apgar score as a complication predictor in gastrointestinal oncologic surgery.

INTRODUCTION AND AIMS: Surgical resection of gastrointestinal (GI) cancer is the cornerstone of curative treatment but entails considerable morbidity. The surgical Apgar score (SAS) is a practical and objective instrument that provides immediate feedback. The aim of the present study was to evaluate the performance of the SAS for predicting complications at 30 days in patients with primary GI cancer that underwent curative surgery. MATERIALS AND METHODS: A prospective observational study was conducted that included 50 patients classified into a low SAS (≤ 4) group or a high SAS (≥ 5) group. Complications were defined as any event classified as a Clavien-Dindo grade II to V event. Bivariate and multivariate analyses were performed through the Cox regression and a p<0.05 was considered significant. RESULTS: Overall postoperative morbidity was 50.0%, with no mortality. Eighty-six percent of cases were catalogued as having an ASA≥3. Eighty-eight percent had a high SAS, of whom 45.5% presented with a complication, whereas 12.0% had a low SAS and a complication rate of 83.3%. In the multivariate analysis, the BMI (OR: 3.351, 95% CI: 1.218-9.217, P=.019), SAS (OR: 0.266, 95% CI: 0.077-0.922, P=.037), surgery duration (OR: 3.170, 95% CI: 1.092-9.198, P=.034), and ephedrine use (OR: 0.356, 95% CI: 0.144-0.880, P=.025) were significantly associated with the development of adverse outcomes. CONCLUSIONS: SAS was shown to be an independent predictive factor of postoperative morbidity at 30 days in the surgical management of GI cancer and appears to offer a reliable sub-stratification in a high-risk population with an ASA≥3.

Recombinant Mycobacterium bovis BCG is a promising platform to develop vaccines against Trypansoma cruzi infection.

Chagas disease, caused by the hemoflagelate parasite Trypanosoma cruzi, is one of the most prevalent endemic parasitoses, affecting 7-8 million people. Due to the complexity of the infection, no vaccines are available at present. The extraordinary adjuvant capacity of bacille Calmette-Guérin (BCG) was explored in this work to develop a vaccine candidate to protect against T. cruzi infection using the recombinant BCG (rBCG) vaccine platform. Three antigens of the parasite corresponding to the N and C terminal fragments of the enzyme trans-sialidase (NT-TS and CT-TS, respectively) and a fragment of the cruzipain enzyme (CZf) were cloned into the vectors pUS997 and pUS2000 and transformed into the BCG Pasteur strain. In vaccinated mice, rBCG expressing NT-TS in pUS2000 plasmid provided the highest protection and the lowest parasitemia after challenging BALB/c mice with a 50% lethal dose of parasites. When mice vaccinated with pUS2000-NT-TS were challenged with a 100% lethal dose of parasite, high levels of protection were also obtained, together with a low degree of cardiac lesions 120 days after infection. In immunized mice with pUS2000-NT-TS/rBCG clone, the proliferation of CD4+ cells from splenocytes stimulated with the TS antigen was significant; this stimulation increased interferon (IFN)-γ and interleukin (IL)-17 within CD4⁺ T lymphocytes (LTCD4+ ) cells and IFN-γ and CD107 expression within LTCD8+ cells. Therefore, pUS2000-NT-TS/rBCG conferred high levels of protection, which correlated with an immune response orientated towards a T helper type 1 (Th1)/Th17 profile, together with an LTC-specific response, indicating that rBCG is a promising platform to develop vaccines against T. cruzi.

Application of nonlinear sliding mode control to ultrasound contrast agent microbubbles.

A sliding mode control system is developed and applied to a spherical model of a contrast agent microbubble that simulates its radial response to ultrasound. The model uses a compressible form of the Rayleigh-Plesset equation combined with a thin-shell model. A nonlinear control law for the second-order model is derived and used to design and simulate the controller. The effect of the controller on the contrast agent response is investigated for various control scenarios. This work demonstrates the feasibility of using a nonlinear control system to modulate the dynamic response of ultrasound contrast agents, but highlights the need for improved feedback mechanisms and control input methods. Possible applications of the nonlinear control system to contrast agents illustrated in this work include radius stabilization in the presence of an acoustic wave, radial growth and subsequent collapse, and generation of periodic radial oscillations while a contrast agent is within an acoustic forcing regime known to cause a chaotic response.

Dynamical analysis of the nonlinear response of ultrasound contrast agent microbubbles.

The nonlinear response of spherical ultrasound contrast agent microbubbles is investigated to understand the effects of common shells on the dynamics. A compressible form of the Rayleigh-Plesset equation is combined with a thin-shell model developed by Lars Hoff to simulate the radial response of contrast agents subject to ultrasound. The responses of Albunex, Sonazoid, and polymer shells are analyzed through the application of techniques from dynamical systems theory such as Poincaré sections, phase portraits, and bifurcation diagrams to illustrate the qualitative dynamics and transition to chaos that occurs under certain changes in system parameters. Corresponding calculations of Lyapunov exponents provide quantitative data on the system dynamics. The results indicate that Albunex and polymer shells sufficiently stabilize the response to prevent transition to the chaotic regime throughout typical clinical ranges of ultrasound pressure and frequency. By contrast, Sonazoid shells delay the onset of chaos relative to an unshelled bubble but do not prevent it. A contour plot identifying regions of periodic and chaotic behavior over clinical ranges of ultrasound pressure and frequency is provided for Sonazoid. This work characterizes the nonlinear response of various ultrasound contrast agents, and shows that shell properties have a profound influence on the dynamics.

Mutagenic potential of water from Pelotas Creek in Rio Grande do Sul, Brazil.

Water resource degradation is one of mankind's greatest worries, as it causes direct and indirect damage to the associated biota. We initiated a water monitoring study in Pelotas Creek in 2003 in order to assess the mutagenic effect of the creek's waters. Allium cepa cells exposed to water samples and a chronically exposed macrophyte were analyzed, through evaluation of the mitotic index, mitotic anomalies, interphase anomalies, and total anomalies. Five points were chosen along the lower course of Pelotas Creek, from which water samples and floating pennywort (Hydrocotyle ranunculoides, Apiaceae) were collected in 2006 and 2007. The enteric bacterium Escherichia coli was found at all sampling points; in the physical-chemical analysis, a few variables exceeded permitted limits, pH (from 6 to 9), chloride (250 mg/L), hardness (from 10 to 200 mg CaCO(3)/L), and conductivity (100 microOmega/cm). There was an increased number of cytogenetic anomalies in exposed A. cepa cells and in the pennywort in 2006 relative to 2007, which may be explained by the increased rainfall, which was three times greater in 2007 at some stations than in 2006.Omega/cm). There was an increased number of cytogenetic anomalies in exposed A. cepa cells and in the pennywort in 2006 relative to 2007, which may be explained by the increased rainfall, which was three times greater in 2007 at some stations than in 2006.

Prevalencia y resistencia antimicrobiana de especies de shigella aisladas de niños con diarrea en Maracaibo Venezuela / Prevalence and antimicrobial resistence of shigella species isolated in children with diarrhea in Maracaibo Venezuela

Para determinar la prevalencia de shigelosis en niños menores de 6 años de edad, en la ciudad de Maracaibo, durante los años 1995-1999, se procesaron 789 muestras fecales. En 358 (45,4 por ciento) especímenes se detectaron bacterias enteropatógenas. Shigella spp. representó el 72,3 por ciento de las mismas. 174 (67,2 por ciento) aislamientos correspondieron a S.flexneri, 79 (30,5 por ciento) a S. sonnei, 4 (1,5 por ciento) y 2 (0,8 por ciento) a S. boydii S. dysenteriae, respectivamente. El 68 por ciento de los casos se detectó en niños menores de 3 años de edad, produciendose el 36 por ciento en niños menores de 1 año. S. flexneri y S. sonnei se presentaron en todos los grupos etarios. Los dos aislamientos de S. dysenteriae se encontraron en pacientes menores de 1 año de edad. Al estudiar la sensibilidad y resistencia a trimethoprim-sulfametoxazol, ampicilina, carbenicilina, cefalotin, tetraciclinas, piperacilina, cefoperazone, cefamandol, ceftazidima, gentamicina, ampicilina sulbactam, amikacina, aztreonam, netilmicina, colimicina, cloranfenicol y ácido nalidixico, se observó que el 92 por ciento de las 259 cepas de Shigella spp. fue multirresistente (3 a 8 antimicrobianos). El porcentaje de resistencia encontrado para trimethoprim-sulfametoxazol fue 72,2 por ciento, mientras que, para ampicilina y carbenicilina fue del orden del 64,8 por ciento. Las dos cepas de S. dysenteriae fueron resistentes a los tres antimicrobianos mencionados. Los 4 aislamientos de S. boydii desarrollaron resistencia sólo a trimethopim-sulfametoxazol. Para cefalotin la resistencia encontrada fue 34,4 por ciento. Con relación a las cefalosporinas de segunda y tercera generación, los porcentajes de resistencia fueron menores: cefamandol (7,3 por ciento), cepoferazone (7,3 por ciento) y ceftazidima (6,2 por ciento). 4, 6 por ciento de las cepas fueron resistentes a ampicilina sulbactam, 1,5 por ciento a aztreonam y el 10 por ciento a piperacilina. La resistencia desarrollada a los aminoglucosidos fue baja: gentamicina 5,4 por ciento y amikacina 5,8 por ciento, la resistencia para tetraciclinas fue de 28,6, mientras que, para cloranfenicol, ácido nalidixico, colimicina y netilmicina, no se observó resistencia

Portadores nasales de H. influenzae en un preescolar de Maracaibo / Nose carries of H. influenzae to a preschool of Maracaibo

La existencia de tasas de portadores de H. influenzae inusualmente elevadas se ha asociado con mayor riesgo de desarrollar infecciones respiratorias o sistémicas. A fin de determinar la tasa de portadores nasales de este probable patógeno, se procesaron 81 muestras de exudado nasal provenientes de niños preescolares, aparentemente sanos. El aislamiento e identificación se realizó utilizando metodología convencionales. Se realizó además, serotipificación y biotipiaje del microorganismo, así como también pruebas de susceptibilidad a los agentes antimicrobianos, utilizando el método de Baüer & Kirby, siguiendo los lineamientos del NCCLS. Se obtuvo un 20,98 por ciento de cultivos positivos (17 casos), destacando una distribución casi uniforme de los biotipos I, II, IV, V y VI (17,64 por ciento para cada uno) y un 11,80 por ciento para el biotipo III, observándose un predominio de cepas no tipificables (88,24 por ciento). Todas las cepas aisladas resultaron sensibles a los agentes antimicrobianos probados

Squamous cell carcinoma of gingiva and edentulous alveolar ridge: a clinicopathologic study.

All oral squamous cell carcinomas were retrieved from the files of Temple University's Oral Pathology Laboratory from 1967 through 1994 for a clinicopathologic study of those occurring on the gingiva. A total of 1,193 cases had sufficient data for tabulation and statistical analysis, of which 300 (25%) arose on the gingiva or alveolar ridge. The largest number of these cases (211/300) occurred on the mandibular gingiva or alveolar ridge. The mean age of the patients was 66.66 years, with males accounting for 57% of cases. Many case comparison analyses of oral squamous cell carcinomas do not separate oral subsites or specifically address carcinoma of the gingiva. The results were compared with other published series and suggest that further studies are needed because of the wide range of reported figures on the incidence of gingival squamous cell carcinomas.

Single-dose pharmacokinetics and anticonvulsant efficacy of primidone in mice.

The pharmacokinetics and efficacy of the anticonvulsant primidone (PRM) and its active metabolites, phenobarbital (PB) and phenylethylmalonamide (PEMA), were studied after single-dose administration in mice. The half-life of PB is twice that of PRM and PEMA. The plasma/brain ratios provide evidence of poor penetration of PRM into brain. The results support our findings of negligible or absent PRM concentrations in the brains of patients on primidone therapy who were undergoing surgery for intractable epilepsy. The anticonvulsant properties of PRM, PB, and PEMA against maximal electroshock in mice were also studied with the use of the metabolic inhibitor SKF 525A. The half-life, potency, peak anticonvulsant effect, and effective dose curves of these compounds indicate that the anticonvulsant effect of short-term oral PRM administration in mice is from derived PB.

Valproic acid-phenytoin interaction.

The interaction between valproic acid (VPA) and phenytoin (DPH) was examined during therapeutic monitoring in an epileptic outpatient population. Gas-liquid chromatographic methods were used to measure DPH and VPA concentrations. (1) In 12 patients on stable DPH regimens, the mean DPH level declined from 19.7 to 15.3 microgram/ml when VPA was added (p less than 0.001). (2) In 20 patients receiving DPH and VPA, the median free fraction was 15.8%, compared to 9.1% free DPH in 40 patients receiving DPH only or DPH and phenobarbital (p less than 0.001). (3) Addition of VPA to a stable DPH regimen may result in a transient increased risk of DPH toxicity, followed by restabilization at the original free DPH level.

Pharmacokinetic comparison of tablet and suspension dosage forms of carbamazepine.

The bioavailability of two preparations of carbamazepine--the tablet and a new syrup-was studied in 9 adult male volunteers by measuring saliva and serum levels. Peak time was significantly earlier and peak level significantly higher in serum for syrup as compared to tablet. Levels remained higher for syrup for 12 hr. Saliva was contaminated for up to 2 hr by syrup ingestion, possibly for a half hour by the tablet. Beyond that, saliva/serum ratios remained stable. Saliva level variation was too large for pharmacokinetic studies but acceptable for clinical purposes if sampling was long enough after the last dose.

Clinical pharmacology of anti-epileptic drugs: a summary of current information.

This compendium represents what we believe to be the most current and reliable pharmacological data on anticonvulsant drugs. The information presented is derived from determinations of the drugs in plasma or serum by gas--liquid chromatography in studies of the efficacy of anti-epileptic agents. We present information on the limitations of therapeutic concentration ranges, half-lives, active and inactive metabolites, and structure/activity relationships of anticonvulsant drugs. This report provides answers to many of the questions clinicians direct to anticonvulsant-monitoring laboratories. Information on other pharmacoloical variables supplements this review in the interest of the clinical investigator.