Enzymatic synthesis of poly-l-lactide and poly-l-lactide-co-glycolide in an ionic liquid

The syntheses of poly-l-lactide (PLLA) and poly-l-lactide-co-glycolide (PLLGA) is reported in the ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate [HMIM][PF₆] mediated by the enzyme lipase B from Candida antarctica (Novozyme 435). The highest PLLA yield (63%) was attained at 90 °C with a molecular weight (M _n ) of 37.8 × 10³ g/mol determined by size exclusion chromatography. This procedure produced relatively high crystalline polymers (up to 85% PLLA) as determined by DSC. In experiments at 90 °C product synthesis also occurred without biocatalyst, however, PLLA synthesis in [HMIM][PF₆] at 65 °C followed only the enzymatic mechanism as ring opening was not observed without the enzyme. In addition, the enzymatic synthesis of PLLGA is first reported here using Novozyme 435 biocatalyst with up to 19% of lactyl units in the resulting copolymer as determined by NMR. Materials were also characterized by TGA, MALDI-TOF–MS, X-ray diffraction, polarimetry and rheology.     

Enzymatic synthesis of poly-l-lactide-co-glycolide in the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate

This article reports the lipase-catalyzed ring-opening copolymerization of l-lactide (LLA) and glycolide using the commercially available ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate as solvent media. Candida antarctica lipase B, immobilized in an acrylic support was used as biocatalyst. The reaction temperature had a direct influence on yields and molecular weights of the copolymers as well as LLA incorporation. The materials presented semi-crystalline structures assessed by DSC and powder XR diffraction analyses.     

Roles of the main olfactory and vomeronasal systems in the detection of androstenone in inbred strains of mice

We investigated the role of the main olfactory and accessory olfactory systems (MOS and AOS respectively) in the detection of androstenone. We used the following experimental approaches: behavioral, surgical removal of the vomeronasal organ (VNX) followed by histochemical verification and Fos immunohistochemistry. Using a Y-maze paradigm we estimated sensitivity of NZB/B1NJ and CBA/J mice to androstenone. CBA mice were 2,000-fold more sensitive to androstenone than NZB mice. VNX caused a 4- to 16-fold decre...     

Assessing and reporting heterogeneity in treatment effects in clinical trials: a proposal

Background

This paper presents the study protocol for a pragmatic randomised controlled trial to evaluate the impact of a school based program developed to prevent teenage pregnancy. The program includes students taking care of an Infant Simulator; despite growing popularity and an increasing global presence of such programs, there is no published evidence of their long-term impact. The aim of this trial is to evaluate the Virtual Infant Parenting (VIP) program by investigating pre-conceptual health and risk behaviours, teen pregnancy and the resultant birth outcomes, early child health and maternal health.

Methods and Design

Fifty-seven schools (86% of 66 eligible secondary schools) in Perth, Australia were recruited to the clustered (by school) randomised trial, with even randomisation to the intervention and control arms. Between 2003 and 2006, the VIP program was administered to 1,267 participants in the intervention schools, while 1,567 participants in the non-intervention schools received standard curriculum. Participants were all female and aged between 13-15 years upon recruitment. Pre and post-intervention questionnaires measured short-term impact and participants are now being followed through their teenage years via data linkage to hospital medical records, abortion clinics and education records. Participants who have a live birth are interviewed by face-to-face interview. Kaplan-Meier survival analysis and proportional hazards regression will test for differences in pregnancy, birth and abortion rates during the teenage years between the study arms.

Discussion

This protocol paper provides a detailed overview of the trial design as well as initial results in the form of participant flow. The authors describe the intervention and its delivery within the natural school setting and discuss the practical issues in the conduct of the trial, including recruitment. The trial is pragmatic and will directly inform those who provide Infant Simulator based programs in school settings.

Trial registration

ISRCTN24952438     

Improving indicator species analysis by combining groups of sites

Indicator species are species that are used as ecological indicators of community or habitat types, environmental conditions, or environmental changes. In order to determine indicator species, the characteristic to be predicted is represented in the form of a classification of the sites, which is compared to the patterns of distribution of the species found at the sites. Indicator species analysis should take into account the fact that species have different niche breadths: if a species is related to the conditions prevailing in two or more groups of sites, an indicator species analysis undertaken on individual groups of sites may fail to reveal this association. In this paper, we suggest improving indicator species analysis by considering all possible combinations of groups of sites and selecting the combination for which the species can be best used as indicator. When using a correlation index, such as the point‐biserial correlation, the method yields the combination where the difference between the observed and expected abundance/frequency of the species is the largest. When an indicator value index (IndVal) is used, the method provides the set of site‐groups that best matches the observed distribution pattern of the species. We illustrate the advantages of the method in three different examples. Consideration of combinations of groups of sites provides an extra flexibility to qualitatively model the habitat preferences of the species of interest. The method also allows users to cross multiple classifications of the same sites, increasing the amount of information resulting from the analysis. When applied to community types, it allows one to distinguish those species that characterize individual types from those that characterize the relationships between them. This distinction is useful to determine the number of types that maximizes the number of indicator species.     

Multilocus sequence types of Finnish bovine <Emphasis Type="Italic">Campylobacter jejuni</Emphasis> isolates and their attribution to human infections

Background  

Campylobacter jejuni is the most common bacterial cause of human gastroenteritis worldwide. Due to the sporadic nature of infection, sources often remain unknown. Multilocus sequence typing (MLST) has been successfully applied to population genetics of Campylobacter jejuni and mathematical modelling can be applied to the sequence data. Here, we analysed the population structure of a total of 250 Finnish C. jejuni isolates from bovines, poultry meat and humans collected in 2003 using a combination of Bayesian clustering (BAPS software) and phylogenetic analysis.     

Spermatozoa of tapeworms (Platyhelminthes,Eucestoda): advances in ultrastructural and phylogenetic studies

New data on spermiogenesis and the ultrastructure of spermatozoa of ‘true’ tapeworms (Eucestoda) are summarized. Since 2001, more than 50 species belonging to most orders of the Eucestoda have been studied or reinvestigated, particularly members of the Caryophyllidea, Spathebothriidea, Diphyllobothriidea, Bothriocephalidea, Trypanorhyncha, Tetraphyllidea, Proteocephalidea, and Cyclophyllidea. A new classification of spermatozoa of eucestodes into seven basic types is proposed and a key to their identification is given. For the first time, a phylogenetic tree inferred from spermatological characters is provided. New information obtained in the last decade has made it possible to fill numerous gaps in the character data matrix, enabling us to carry out a more reliable analysis of the evolution of ultrastructural characters of sperm and spermiogenesis in eucestodes. The tree is broadly congruent with those based on morphological and molecular data, indicating that convergent evolution of sperm characters in cestodes may not be as common as in other invertebrate taxa. The main gaps in the current knowledge of spermatological characters are mapped and topics for future research are outlined, with special emphasis on those characters that might provide additional information about the evolution of tapeworms and their spermatozoa. Future studies should be focused on representatives of those major groups (families and orders) in which molecular data indicate paraphyly or polyphyly (e.g. ‘Tetraphyllidea’ and Trypanorhyncha) and on those that have a key phylogenetic position among eucestodes (e.g. Diphyllidea, ‘Tetraphyllidea’, Lecanicephalidea, Nippotaeniidea).     

Accuracy of Monoclonal Stool Tests for Determining Cure of Helicobacter pylori Infection After Treatment

Background: Studies comparing new monoclonal fecal tests for evaluating cure of Helicobacter pylori infection after treatment are scarce. The objective was to compare the diagnostic accuracy of three monoclonal stool tests: two rapid in‐office tools –RAPID Hp StAR and ImmunoCard STAT! HpSA – and an EIA test – Amplified IDEIA Hp StAR. Materials and methods: Diagnostic reliability of the three tests was evaluated in 88 patients at least 8 weeks after H. pylori treatment. Readings of immunochromatographic tests were performed by two different observers. Sensitivity, specificity, positive and negative predictive values and 95% confidence intervals were calculated. Results: All tests presented similar performance for post‐eradication testing. Sensitivity for detecting persistent infection was 100% for both Amplified IDEIA and RAPID Hp StAR and 90% for ImmunoCard STAT! HpSA. Respective specificities were 94.9%, 92.3–93.6% and 94.9%. Negative predictive values were very high (100%, 100% and 98.7% respectively). But positive predictive values were lower, ranging from 62.5 to 71.4%. Conclusion: All monoclonal fecal tests in this series presented similar performance in the post‐treatment setting. A negative test after treatment adequately predicted cure of the infection. However, nearly a third of tests were false positive, showing a poor predictive yield for persistent infection.     

Effect of mitochondrial genome rearrangement on respiratory activity, photosynthesis, photorespiration and energy status of MSC16 cucumber (Cucumis sativus) mutant

The effects of changes in mitochondrial DNA in cucumber ( Cucumis sativus L.) mosaic mutant (MSC16) on respiration, photosynthesis and photorespiration were analyzed under non-stressed conditions. Decreased respiratory capacity of complex I in MSC16 mitochondria was indicated by lower respiration rates of intact mitochondria with malate and by rotenone-inhibited NADH or malate oxidation in the presence of alamethicin. Moreover, blue native PAGE indicated decreased intensity of protein bands of respiratory chain complex I in MSC16 leaves. Concerning the redox state, complex I impairment could be compensated to some extent by increased external NADH dehydrogenases (ND_exNADH) and alternative oxidase (AOX) capacity, the latter presenting differential expression in the light and in the dark. Although MSC16 mitochondria have a higher AOX protein level and an increased capacity, the AOX activity measured in the dark conditions by oxygen discrimination technique is similar to that in wild-type (WT) plants. Photosynthesis induction by light followed different patterns in WT and MSC16, suggesting changes in feedback chloroplast ΔpH caused by different adenylate levels. At steady-state, net photosynthesis was only slightly impaired in MSC16 mutants, while photorespiration rate (PR) was significantly increased. This was the result of large decreases in both stomatal and mesophyll conductance to CO₂, which resulted in a lower CO₂ concentration in the chloroplasts. The observed changes on CO₂ diffusion caused by mitochondrial mutations open a whole new view of interaction between organelle metabolism and whole tissue physiology. The sum of all the described changes in photosynthetic and respiratory metabolism resulted in a lower ATP availability and a slower plant growth.