Effect of the Melicoccus bijugatus leaf and fruit extracts and acidic solvents on the antimicrobial properties of chitosan-starch films.

AIM: Analysing the antimicrobial activity-against food-borne micro-organisms-of modified chitosan-starch films using formic and acetic acid as chitosan solvents and Melicoccus bijugatus leaves and fruit extracts. METHODS AND RESULTS: The films' antimicrobial activity against mesophilic aerobic bacteria, total coliform and fungi were also analysed, in accordance with the Mexican Official Norms (NOM-092-SSA1-1994, NOM-111-SSA1-1994 and NOM-113-SSA1-1994). The pH values of the films and extracts were measured, and the volatile compounds of the extracts and two films were determined by Gas Chromatography-Mass Spectrometry (GC-MS) considering the relationship among the type of compounds, extracts concentration, films' pH and the antimicrobial activity against bacteria and fungi. The best results are obtained by films with formic acid and 10% (v/v) of leaf and fruit extracts, in comparison with untreated chitosan-starch films. CONCLUSIONS: The extracts' compounds improved the films' antimicrobial capacity and inhibited the growth of micro-organisms with no previous sterilization required. It is correlated to the pH of the media, the combination of solvent/extract used and its concentration. SIGNIFICANCE AND IMPACT OF THE STUDY: This is one of the few researches where the antimicrobial activity of M. bijugatus extracts is studied. It was found that the presence of these extracts is capable of improving the antimicrobial activities of chitosan-starch films. The performance of the modified films suggests their potential application as novel food packaging materials and encourages further research.

Functional analysis of challenging behavior in people with severe intellectual disabilities.

Challenging behaviors exhibited by individuals with developmental disabilities often hinder the acquisition of academic, social, and life skills. Functional analysis has been useful for assessing challenging behavior in various settings. The purpose of this study was to implement an operant methodology for recognizing the functional properties of challenging behavior in people with intellectual disabilities. Four adults diagnosed with profound intellectual disability received assessment under several experimental conditions using a functional analysis methodology: social attention as positive reinforcement, negative reinforcement such as the termination of demands, positive tangible reinforcements, absence of social contingencies, and escape from noisy stimuli. Results showed that different types of reinforcement or avoiding contingencies affected the rate of aggression, self-injury, disruption, stereotypy, or socially offensive behaviors, and functional analysis may potentially be a viable alternative for identifying challenging behaviors.

Numerical Estimation and Mathematical Learning Methodology in Preschoolers.

One of the means for representing quantities/magnitudes is the mental number line. It is still a nonsolved question as to whether the method of learning mathematics in the early years could improve this type of estimating. A total of 233 students, aged four and five years, who learned mathematics with a new method called Open Algorithm Based on Number or the more traditional Closed Based on Ciphers approach, were evaluated with a reliable estimation on the number line test. Results revealed significant differences in participants' estimation functions based on the learning method used. Students who learned mathematics through the Open Algorithm Based on Number method used a linear representation more efficiently than those who were taught with the Closed Based on Ciphers methodology. This group exhibited a logarithmic function in their approach. We discussed whether these differences can be attributed to a recurrent practice in estimation tasks at school, characterized by the Open Algorithm Based on Number methodology.

Exposure to extrinsic risk factors in prevalence surveys of hospital-acquired infections: a methodological approach.

The difficulties encountered in studying the presence of extrinsic risk factors in the framework of prevalence surveys of hospital-acquired infections (HAI) have led to the use of a variety of methodological approaches. This study examined the effect of retrospective approaches for obtaining data regarding exposure to extrinsic risk factors. The EPINE database for 1990 was used and a simulation model was created. All the evaluated approaches differed in their impact upon the association between risk factors and infections. Prevalence of exposure on the day of the survey, prevalence of exposure at any time before the survey was conducted, and total prevalence were found to be significantly associated with the probability of exposure and duration of exposure. For exposure periods of less than four days, the prevalence of exposure during the week prior to the survey was higher than that encountered on the day of the survey. In studying exposure to risk factors retrospectively, no evidence-based justification could be found to determine how many days prior to the day of actual exposure should be included in the study. However, the site of infection determined the proportion of devices removed due to HAI, and this proportion was not very high in this study. Limiting data to recording the presence of the risk factor on the day of the survey, without investigating past exposures, can provide an adequate estimate of the burden of extrinsic risk factors in one-day, point-prevalence surveys.

[Comparative effects of terbutaline sulphate and ipratropium bromide on the respiratory system (author's transl)]. / Estudio comparativo de los efectos respiratorios de la terbutalina y el ipratropio.

Bronchodilator action of two pharmacologically different drugs have been compared. Ipratropium bromide (Sch 1000) is a synthetic atropine derivative and terbutaline sulphate is a beta-stimulating agent. Twelve asthmatic patients and eight patients with chronic bronquitis received terbutaline 0.50 mg. and ipratropium 0.04 mg by aerosol inhalation. Both drugs were given at random on a consecutive-day schedule. All patients were clinically stable before treatment (basal FEV/VC less than 60 percent). Total lung capacity (TLC) forced expiratory volume (FEV), SRaw, and V'/V curves before and at 15, 60, 120, and 240 minutes after the produce administration were registered. Presence of side-effects was also checked. An intensive bronchodilator action was observed either after inhalation of ipratropium bromide or terbutaline, but statistical studies showed no significant differences between both drugs in relation to intensity and duration of their actions. Sch 1000 caused similar bronchodilator effects in all cases; a more intense effect in patients with chronic bronchitis could not be noticed. Evaluation of V'/V curve, and especially its relation to a same pulmonary volume, pointed out that both drugs act upon small respiratory airways. Advance side-effects were not present.

Acquisition of basic concepts by children with intellectual disabilities using a computer-assisted learning approach.

Computer-assisted learning can be an efficient learning-teaching procedure. Although there is an extensive educational software tradition for this approach, few have better performance than standard drill-and-practice methods. In this work, the specific software "Let's Play With..." was designed to teach concepts of colours, shapes, and body position to children with intellectual disabilities. The software structure follows the Gagné instructional design and applied behaviour analysis. The program was carried out with 39 boys and 21 girls who were special education students in the Cadiz School District. Statistically significant differences were found between groups taught with and without the software.

Relationship of arithmetic problem solving and reflective-impulsive cognitive styles in third-grade students.

Different individuals approach mathematical problems in a variety of ways, with these different approaches also reflected in over-all cognitive styles. This investigation had two purposes, first, to determine whether good and poor arithmetic problem solvers differ substantially in cognitive style, and second, to determine whether the students, after training in techniques of solving arithmetic problems, improve their performance with no significant change in cognitive style. A total of 98 third graders participated (mean age 8.1 yr.; 50 boys, 48 girls). The Matching Familiar Figure Test was used to classify the students by cognitive style as either Reflective or Impulsive. Students also were given training with different problem-solving exercises for different arithmetic problems. The training program in problem-solving strategies did not improve performance on arithmetic problems for Reflective students; however, Impulsive students' performance did improve after training.

Genetic similarity among one Aspergillus flavus strain isolated from a patient who underwent heart surgery and two environmental strains obtained from the operating room.

We report the simultaneous isolation of one Aspergillus flavus strain from the aortic prosthesis of a heart surgery patient and another two isolates recovered from a dual-reservoir cooler-heater used in the operating room where this patient was operated on. Genetic typing of these three isolates by randomly amplified polymorphic DNA (RAPD) revealed identical genotypes. Eight unrelated control strains of A. flavus had eight different genotypes. These results clearly indicated the nosocomial origin of the A. flavus strain isolated from the patient. We suggest that the RAPD technique is a rapid and reliable tool to ascertain the epidemiology of infections caused by A. flavus.