Effects of cactus pear clone harvest seasons and times on the physicochemical and technological properties of resulting mucilage and biopolymeric films

Cactus pear cladodes, clones 'Miúda' (MIU) and 'Orelha de Elefante Mexicana' (OEM) were harvested at 6 am and 8 pm during the rainy-dry, dry and rainy seasons to evaluate the effect of type of clone and harvest seasons on the physicochemical and technological properties of mucilage as well as the optical, physicochemical, mechanical, thermal and microstructural characteristics of the films obtained. The mucilage of the OEM clone presented a higher content of phenolic compounds, compared to the Nopalea genus, regardless of the season and time of harvest. Furthermore, the dry period resulted in higher carbohydrate levels, regardless of the harvest time. The biopolymeric films produced from the OEM clone harvested in the rainy season and rainy-dry transition showed darker color, better mechanical properties, water barrier, compact microstructure and thermal stability when compared to the MIU clone. Furthermore, harvesting at 6 am provided improvements in the mechanical conditions, permeability and thermal stability of the films of both types of clones studied. These results showed strong environmental modulation, naturally incorporating important macromolecules such as carbohydrates and phenolic compounds, used in the industry in the production of nutraceutical foods, into the mucilage. Furthermore, harvesting cladodes at 6 am in the rainy and transitional (rainy-dry) periods provided better quality biopolymeric films and/or coatings.

Chemometric methods in antimalarial drug design from 1,2,4,5-tetraoxanes analogues

A set of 23 steroidal 1,2,4,5-tetraoxane analogues were studied using quantum-chemical method (B3LYP/6-31 G*) and multivariate analyses (PCA, HCA, KNN and SIMCA) in order to calculate the properties and correlate them with antimalarial activity (log RA) against Plasmodium falciparum clone D-6 from Sierra Leone. PCA results indicated 99.94% of the total variance and it was possible to divide the compounds into two classes: less and more active. Descriptors responsible for separating were: highest occupied molecular orbital energy (HOMO), bond length (O1-O2), Mulliken electronegativity (χ) and Bond information content (BIC0). We use HCA, KNN and SIMCA to explain relationships between molecular properties and biological activity of a training set and to predict antimalarial activity (log RA) of 13 compounds (#24-36) with unknown biological activity. We apply molecular docking simulations to identify intermolecular interactions with a selected biological target. The results obtained in multivariate analysis aided in the understanding of the activity of the new compound's design (#24-36). Thus, through chemometric analyses and docking molecular study, we propose theoretical synthetic routes for the most promising compounds 28, 30, 32 and 36 that can proceed to synthesis steps and in vitro and in vivo assays.

Matrix metalloproteinase-8 levels in periodontal disease patients: A systematic review

Periodontal disease is characterized as a disorder of the oral microbiota resulting in an immune response which, in turn, leads to the destruction of periodontal tissue. Matrix metalloproteinase-8 (MMP-8) has been reported as the major metalloproteinase involved in periodontal disease, being present at high levels in gingival crevicular fluid and salivary fluid (SF). The aim of this systematic review was to evaluate the scientific literature regarding the expression of MMP-8 in gingival crevicular fluid and SF in patients with periodontal disease, analyzing its validity as a possible biomarker in the diagnosis of periodontal disease. A systematic review of the literature was performed using the PubMed/Medline, CENTRAL and Science Direct databases. Studies concerning the use of MMP-8 in the diagnosis of periodontal disease that evaluated its effectiveness as a biomarker for periodontal disease were selected. The search strategy provided a total of 6483 studies. After selection, six articles met all the inclusion criteria and were included in the present systematic review. The studies demonstrated significantly higher concentrations of MMP-8 in patients with periodontal disease compared with controls, as well as in patients presenting more advanced stages of periodontal disease. The findings on higher MMP-8 concentrations in patients with periodontal disease compared with controls imply the potential adjunctive use of MMP-8 in the diagnosis of periodontal disease.

Combining Multiple Comparisons and Modeling Techniques in Dose-Response Studies

The analysis of data from dose-response studies has long been divided according to two major strategies: multiple comparison procedures and model-based approaches. Model-based approaches assume a functional relationship between the response and the dose, taken as a quantitative factor, according to a prespecified parametric model. The fitted model is then used to estimate an adequate dose to achieve a desired response but the validity of its conclusions will highly depend on the correct choice of the a priori unknown dose-response model. Multiple comparison procedures regard the dose as a qualitative factor and make very few, if any, assumptions about the underlying dose-response model. The primary goal is often to identify the minimum effective dose that is statistically significant and produces a relevant biological effect. One approach is to evaluate the significance of contrasts between different dose levels, while preserving the family-wise error rate. Such procedures are relatively robust but inference is confined to the selection of the target dose among the dose levels under investigation. We describe a unified strategy to the analysis of data from dose-response studies which combines multiple comparison and modeling techniques. We assume the existence of several candidate parametric models and use multiple comparison techniques to choose the one most likely to represent the true underlying dose-response curve, while preserving the family-wise error rate. The selected model is then used to provide inference on adequate doses.

On a hybrid method in dose finding studies

OBJECTIVES

Combination of multiple testing and modeling techniques in dose-response studies. Use of hypotheses tests to assess the significance of the dose-response signal associated with a given candidate dose-response model. Estimation of target dose(s) following the previous model selection step. Illustration of the method with a real data example.

METHODS

We assume a set of candidate models potentially reflecting the data generating process. The appropriateness of each individual model is evaluated in terms of contrast tests, where each set of contrast weights describes a specific dose-response shape. Optimum contrast weights are computed, which maximize the non-centrality parameters associated with the contrast tests. A reference set of appropriate candidate models is obtained while controlling the familywise error rate. A single model is then selected from this reference set using standard model selection criteria. The final step is devoted to dose finding by applying inverse regression techniques. This is illustrated for estimating the minimum effective dose.

RESULTS

The method is as powerful as competing standard dose-response tests to detect an overall dose-related trend. In addition, the possibility is given to estimate one or more target doses of interest. The analysis of a real data example confirms the advantages of the proposed hybrid method.

CONCLUSIONS

Combining multiple testing and modeling techniques leads to a powerful tool, which uses the advantages of both approaches: Rigid error control at the significance testing step and flexibility at the dose estimation step. The method can be extended to handle more general linear models including covariates and factorial treatment structures.

Estimating significance level and power comparisons for testing multiple endpoints in clinical trials

Clinical trials generally include several outcome measures of interest for assessing treatment efficacy and harm. Traditionally a single measure, the primary outcome, is selected and used as the basis for the design, including sample size and power. Secondary outcomes are then generally ordered with respect to their clinical relevance and importance. While this has become the traditional paradigm, recent trials have suggested the need for additional approaches. In this setting, two outcomes are viewed as key, either one being sufficient for proof of efficacy, but with an ordering of preference. The basic question, in such cases, is how to control the overall significance level for the trial. We describe and compare two methods for testing primary and secondary endpoints, accounting for their hierarchical nature-the ordering preference. Both methods are sequential, in the sense that the secondary endpoint is only tested when the primary outcome fails to reach significance. The first method uses a global test for the combination of the primary and secondary endpoints, while the second uses a partial Bonferroni correction. Simulation results indicate that the Bonferroni adjustment method performs as well as the global test method in most cases, and even better in some cases.

Prediction of the developmental potential of hamster embryos in vitro by precise timing of the third cell cycle

Time-lapse videomicrography was used to determine the timing of early developmental events in hamster embryos in vitro. The time intervals from pronuclear envelope breakdown to the completion of the first cleavage (Dt2), second cleavage (Dt4 = 2-4 cells), third cleavage (Dt8 = 4-8 cells), blastocyst formation, and zona escape were precisely measured to determine whether the variable 'time' (t) can be used to predict the developmental potential of preimplantation embryos. The range of the developmental time interval (Dt) from the second to the third cleavage divisions (Dt8) provided the best indicator for predicting the probabilities of blastocyst formation and zona escape (P = 0.015 and 0.041, respectively). Dt8 was subdivided into consecutive time cutoff points of < or = 750, < or = 800, < or = 850 and < or = 900 min. Of the embryos that took < or = 750 min to complete the third cleavage division, 92% developed into blastocysts and 69% escaped from their zonae pellucidae. When the completion of Dt8 extended to < or = 900 min, the percentages decreased to 75% and 49% for blastocyst formation and zona escape, respectively. This study identifies a specific developmental time interval and a model whereby time can be used as a noninvasive parameter to predict embryo developmental potential in vitro.

[A measure to evaluate estimates from the population census]

"A measure of efficiency loss for the precision of estimates implied by sampling fractions reduction is described here....A study of the sampling fractions needed to guarantee a given precision level to estimate characteristics...is also performed. An application of the methodology suggested is included. The example is based on household characteristics investigated in [Brazil's]... Census of 1980, with estimates published at a county level and for the set of alternative sampling fractions for the 1990... Census." (SUMMARY IN ENG)