Use of coupling agents to enhance the interfacial interactions in starch-EVOH/hydroxylapatite composites.

Different zirconate, titanate and silane coupling agents were selected in an effort to improve the mechanical properties of starch and ethylene-vinyl alcohol copolymer (EVOH) hydroxylapatite (HA) composites, through the enhancement of the filler particles-polymer matrix interactions and the promotion of the interfacial adhesion between these two phases. The mechanical performance was assessed by tensile tests and discussed on the basis of the respective interfacial morphology (evaluated by scanning electron microscopy). The main relevant parameters were found to be the surface properties and reactivity of the filler (non-sintered HA) and the chemical nature (pH and type of metallic centre) of the added coupling agent. Significant improvements in the stiffness were achieved (about 30% increase in the modulus) when using the acidic zirconate coupling agents. The acidic zirconate combined the capability of crosslinking the polymer matrix with the establishment of donor-acceptor interactions and hydrogen bonding between it and the ceramic particles, leading to very good interfacial adhesion. The optimization of these coupling processes associated with the introduction of higher amounts of filler, may be an effective way to produce composites with mechanical properties analogous to those of the human cortical bone.     

Birth weight and adult bone mass: a systematic literature review

Summary  

This systematic literature review comprised 16 studies. The association of birth weight with bone parameters was much more evident for bone mineral content (BMC) rather than bone mineral density (BMD). This is an important finding since a reduction in BMC is strongly associated with an increased risk of fractures.     

Evaluation of the protective effects of quercetin in the hepatopulmonary syndrome.

The hepatopulmonary syndrome (HPS) occurs when intrapulmonary dilatation causes hypoxemia in cirrhosis. The free radicals may play a significant contributory role in the progression of HPS, and flavonoid agents could protect against deleterious effects of free radicals. The flavonoid quercetin was evaluated in an experimental model of biliary cirrhosis induced by bile duct ligation (BDL) in rats. Quercetin was administered at 50mg/kg for 14 days to cirrhotic and non-cirrhotic rats. Bone marrow was extracted from animals to analyze micronuclei. Lung, liver and blood were extracted to detect DNA damage using the comet assay. The results showed that the micronuclei and DNA damages to lung and liver were increased in BDL rats. Quercetin caused no damage to the DNA while decreasing the occurrence of micronucleated cells in bone marrow as well as DNA damage to lung and liver in cirrhotic rats. Quercetin showed antimutagenic activity against hydroperoxides as evaluated by the oxidative stress sensitive bacterial strains TA102 Salmonella typhimurium and IC203 Escherichia coli, suggesting protection by free radical scavenging. In Saccharomyces cerevisie yeast strains lacking mitochondrial or cytosolic superoxide dismutase, these results indicate that quercetin protects cells by induction of antioxidant enzymes. The present study is the first report of genotoxic/antigenotoxic effects of quercetin in a model of animal cirrhosis. In this model, quercetin was not able to induce genotoxicity and, conversely, it increased the genomic stability in the cirrhotic rats, suggesting beneficial effects, probably by its antioxidant properties.     

Identification of morphologically similar Rhodnius species (Hemiptera: Reduviidae: Triatominae) by electrophoresis of salivary heme proteins

We examined intraspecific variability in the genus Rhodnius using starch gel electrophoresis of salivary heme proteins. Salivary protein profiles of 8 Rhodnius species (R. prolixus, R. robustus, R. neglectus, R. nasutus, R. ecuadoriensis, R. pallescens, R. pictipes, and R. domesticus) were compared. All species could be distinguished by this technique. The greatest protein polymorphism was found in R. ecuadoriensis, R. nasutus, R. robustus, and R. pictipes, followed by R. prolixus, R. neglectus, R. pallescens, and R. domesticus. This approach was able to distinguish R. prolixus from R. robustus and R. neglectus from R. nasutus, species with extreme phenotypical similarity.     

Electrophysiological evidence for a defect in the processing of temporal sound patterns in multiple sclerosis

OBJECTIVES: To assess the processing of spectrotemporal sound patterns in multiple sclerosis by using auditory evoked potentials (AEPs) to complex harmonic tones. METHODS: 22 patients with definite multiple sclerosis but mild disability and no auditory complaints were compared with 15 normal controls. Short latency AEPs were recorded using standard methods. Long latency AEPs were recorded to synthesised musical instrument tones, at onset every two seconds, at abrupt frequency changes every two seconds, and at the end of a two second period of 16/s frequency changes. The subjects were inattentive but awake, reading irrelevant material. RESULTS: Short latency AEPs were abnormal in only 4 of 22 patients, whereas long latency AEPs were abnormal to one or more stimuli in 17 of 22. No significant latency prolongation was seen in response to onset and infrequent frequency changes (P1, N1, P2) but the potentials at the end of 16/s frequency modulations, particularly the P2 peaking approximately 200 ms after the next expected change, were significantly delayed. CONCLUSION: The delayed responses appear to be a mild disorder in the processing of change in temporal sound patterns. The delay may be conceived of as extra time taken to compare the incoming sound with the contents of a temporally ordered sensory memory store (the long auditory store or echoic memory), which generates a response when the next expected frequency change fails to occur. The defect cannot be ascribed to lesions of the afferent pathways and so may be due to disseminated brain lesions visible or invisible on magnetic resonance imaging.     

Comparison of functional activity performance in normally developing children and children with cerebral palsy

OBJECTIVE: To compare the pattern of self-care performance in normal children and children with cerebral palsy (CP). METHOD: 142 normal children and 33 children with CP were evaluated by 22 items from the self-care scale of the PEDI functional test. Rasch methodology transformed scores into interval measures of difficulty from 0 to 100 (logit). Spearman rank correlation coefficient compared the order of logits in the two groups. RESULTS: Eleven items showed significant differences in the logit values received. Out of these, 7 items showed relative difficulty values greater in the group of children with CP and 4 items showed relative difficulty values greater among normal children. A significant correlation was observed in the order of the 22 items displayed in the two interval scales. CONCLUSION: The results suggest that the development of self-care functional activities may be influenced by the presence of CP. These results may support assessment and intervention strategies for children with neuromotor disorders.