Kinetic study of the thermal denaturation of a hyperthermostable extracellular α-amylase from Pyrococcus furiosus.

Hyperthermophilic enzymes are of industrial importance and interest, especially due to their denaturation kinetics at commercial sterilisation temperatures inside safety indicating time-temperature integrators (TTIs). The thermal stability and irreversible thermal inactivation of native extracellular Pyrococcus furiosus α-amylase were investigated using differential scanning calorimetry, circular dichroism and Fourier transform infrared spectroscopy. Denaturation of the amylase was irreversible above a Tm of approximately 106°C and could be described by a one-step irreversible model. The activation energy at 121°C was found to be 316kJ/mol. Using CD and FT-IR spectroscopy it was shown that folding and stability greatly increase with temperature. Under an isothermal holding temperature of 121°C, the structure of the PFA changes during denaturation from an α-helical structure, through a ß-sheet structure to an aggregated protein. Such data reinforces the use of P. furiosus α-amylase as a labile species in TTIs.

Quantification of autolysis in Penicillium chrysogenum by semiautomated image analysis.

An image analysis method is described for the characterization of empty (autolyzed and inactive) regions within the mycelia of filamentous fungi. It extends a previous method that characterized only regions filled with cytoplasm or vacuoles (i.e., the active biomass). The method is semiautomatic, requiring some manual editing before automated measurements. When the method was used for samples from a batch fermentation of an industrial strain of Penicillium chrysogenum, the empty regions were observed to constitute up to 15% (by projected area) of the biomass during the growth phase. After nutrient exhaustion, however, the proportion of empty regions rose rapidly, eventually representing more than 50% of the biomass by the end of fermentation. The increase in the percentage of empty regions coincided with a decrease in biomass (as measured by dry cell weight) and a fall in penicillin titre. Further morphological analysis revealed that fragmentation of mycelia, particularly clumps, coincided with increases in the levels of empty regions. This new image analysis method gave additional information on hyphal differentiation and a measure of autolysis. It was also a useful indicator of the processes leading to autolysis.

Participatory health development in rural Nepal: clarifying the process of community empowerment.

Community-based participatory development empowers villagers to develop community cohesion and confidence, increase their ability to identify, analyze, and priorize their own needs, and organize the resources to meet these needs. An important first step in the process involves establishing a cohesive and functional community group. The authors believe that this is best accomplished through villagers' critical examination of their experiences with development including their understanding of reasons for success or failure, and the gradual emergence of a model of working together that acknowledges and builds on participation and collective expertise. This approach to development is demonstrating encouraging results in a rural area of western Nepal in a university affiliated Canadian/Nepali Health Development Project. This paper describes two mini-projects to illustrate the evolution of group formation through reflection, analysis, and action, and identifies outcomes that could serve as indicators of community empowerment. The paper also presents a generic model of empowerment, and offers lessons learned by the project through the application of the empowerment process to sustainable health development.

PIP: The Nepal Health Development Project's promotion of empowerment through analysis and action has led to a strong sense of community identity, an open decision-making structure, sensitivity to gender and social inequality, skill dissemination, and two-way interaction with resource agencies. The community-based participatory development method is elucidated through the description of two mini-projects: a market garden and reservoir scheme among households who share a water source for irrigation and the introduction by women of smokeless stoves. Outcomes common to both projects included an end to the monopolization by some castes of group leadership roles, leader accountability for their actions, pressure on elected village leaders to act on the community's behalf, increases in women's participation to over 50% of organized groups, and a widened social network. The Project has delineated a dynamic model of the empowerment process that includes the steps of group analysis, community action, reflection, and sustainable health development. The Nepal experience suggests that health programs are rarely cited as a community priority; required first are community readiness to engage in an interactive dialogue with health system agents and a willingness on the part of the external agents to respect newly acquired community competencies.

Classification and measurement of fungal pellets by automated image analysis.

An automated image analysis method for classifying and measuring pellets of filamentous fungi growing in submerged fermentations has been developed. The method discriminates between pelleted mycelial growth and loose aggregates of dispersed hyphae. Pellets are classified into smooth and hairy types. In both cases, the core of the pellet is identified and its shape and size characterized. For hairy pellets the annular region is also characterized. The method was tested on pellets of Aspergillus niger ATCC 11414 grown in a defined medium in shake flasks. This rapid method makes practical extensive studies on the morphology of pellets in submerged fermentations and the influence of fermentation conditions on that morphology.

Field independence and laterality in the perception of faces.

For a sample of 28 college males the degree of left visual-field bias in the perception of faces correlated .45 (p less than .01) with extent of field-independent performance, as assessed by a composite score based on the Embedded-Figures Test, the Rod-and-Frame Test, and ratings on the Articulation-of-Body-Concept Scale. In a second study with 16 female and 10 male college subjects using the Group Embedded-Figures Test, field-independent subjects again showed greater left visual-field lateralization of face perception (r = .43, p less than .05). Based on Witkin's view of field independence as a manifestation of psychological differentiation, possible links between extent of differentiation at the psychological and neurophysiological levels are suggested.