Characterization with crossed immunoelectrophoresis of some antigens differentiating a virulent Candida albicans from its derived, avirulent strain

Antigenic differences between a wild-type virulent Candida albicans 4918 (wt) and its spontaneous avirulent mutant (m-10) were found with crossed immunoelectrophoresis. Yeast cell extracts as well as soluble protein and mannoprotein fractions obtained by affinity chromatography on concanavalin A (Con A) were analyzed. Sera from patients with candidiasis and antisera from rabbits infected with live wt cells and boosted with wt extracts or rabbits immunized with purified wt cell wall preparation were used as counter reactants. Qualitative differences in serum precipitins formed by patients with suspected or culture-proven candidiasis to polysaccharide antigens of wt and m-10 origin were observed. In comparison, except for a spike-formed precipitate detected only with the wt extract, the serum from infected rabbits precipitated the wt and m-10 cell wall polysaccharide antigens about equally. The same type of precipitate was also found with the Con A wt mannoprotein fractions but was again lacking with the m-10 mannoproteins. This precipitate, with extremely slow electromobility in the first dimension, may be related to some special immunodeterminant of the wt mannan molecule. No substantial differences in the precipitation patterns of the Con A wt and m-10 proteins were found when analyzed with patients' sera or rabbit anti-cell sera. However, using these protein fractions with anti-cell wall sera revealed a larger number of precipitates for the wt as opposed to the m-10 strain. The observed antigenic differences between the virulent- and the avirulent-derived strains seem to be mainly associated with cell wall determinants (components) and might be related to the greater adherence and infectivity of the wild strain.     

Regulation and solubilization of Candida albicans chitin synthetase.

A cytoplasmic component which inhibited the activation of chitin synthetase was studied in the dimorphic fungus Candida albicans. The inhibitor was found to be heat stable and trypsin sensitive and was only effective when incubated with a vacuolar protease, an activator of chitin synthetase, before the activation of chitin synthetase. In addition, the particulate chitin synthetase from the yeast form of C. albicans was solubilized by a sodium cholate-digitonin extraction and subsequently was purified approximately 30-fold by Sepharose column chromatography and Amicon XM 100 filtration. Activity of the soluble enzyme was increased by the addition of trypsin or phosphatidyl serine. The molecular weight of the enzyme was estimated to be 400,000.     

Visual adaptations in a diurnal rodent,<Emphasis Type="Italic"> Octodon degus</Emphasis>

The degu (Octodon degus) is a diurnal rodent, native to Chile. Basic features of vision and visual organization in this species were examined in a series of anatomical, electrophysiological and behavioral experiments. The lens of the degu eye selectively absorbs short-wavelength light and shows a progressive increase in optical density as a function of age. Electroretinograms recorded using a flicker-photometric procedure reveal three spectral mechanisms: a rod with peak sensitivity of about 500 nm and two types of cone having respective spectral peaks of about 362 nm and 507 nm. Opsin antibody labeling was used to determine the retinal distributions of the three receptor types. A total of about one-third of the approximately 9 million photoreceptors of the degu retina are cones with the two types (507 nm/362 nm) represented in a ratio of about 13:1. The contributions to vision of all three receptor types were examined in a series of behavioral experiments. A consistent feature of both the electrophysiological and behavioral results is that relatively high levels of light adaptation are required to effect the full transition from rod-based to cone-based vision. In behavioral tests degus were shown to be able to make color discriminations between ultraviolet and visible lights.     

Control of stem cell fate by engineering their micro and nanoenvironment

Stem cells are capable of long-term self-renewal and differentiation into specialised cell types, making them an ideal candidate for a cell source for regenerative medicine. The control of stem cell fate has become a major area of interest in the field of regenerative medicine and therapeutic intervention. Conventional methods of chemically inducing stem cells into specific lineages is being challenged by the advances in biomaterial technology, with evidence highlighting that material properties are capable of driving stem cell fate. Materials are being designed to mimic the clues stem cells receive in their in vivo stem cell niche including topographical and chemical instructions. Nanotopographical clues that mimic the extracellular matrix(ECM) in vivo have shown to regulate stem cell differentiation. The delivery of ECM components on biomaterials in the form of short peptides sequences has also proved successful in directing stem cell lineage. Growth factors responsible for controlling stem cell fate in vivo have also been delivered via biomaterials to provide clues to determine stem cell differentiation. An alternative approach to guide stem cells fate is to provide genetic clues including delivering DNA plasmids and small interfering RNAs via scaffolds. This review, aims to provide an overview of the topographical, chemical and molecular clues that biomaterials can provide to guide stem cell fate. The promising features and challenges of such approaches will be highlighted, to provide directions for future advancements in this exciting area of stem cell translation for regenerative medicine.     

Evaluation of Mite-Away-II™ for fall control of <Emphasis Type="Italic">Varroa destructor</Emphasis> (Acari: Varroidae) in colonies of the honey bee <Emphasis Type="Italic">Apis mellifera</Emphasis> (Hymenoptera: Apidae) in the northeastern USA

Mite-Away II™, a recently-registered product with a proprietary formulation of formic acid, was evaluated under field conditions in commercial apiaries in upstate New York (USA) for the fall control of Varroa destructor Anderson & Trueman in colonies of the honey bee, Apis mellifera L. Ambient temperatures during the treatment period were in the lower half of the range recommended on the label, but were typical for early fall in upstate New York. Average mite mortality was 60.2 ± 2.2% in the Mite-Away II group and 23.3 ± 2.6% in the untreated control group. These means were significantly different from each other, but the level of control was only moderate. These results demonstrate that Mite-Away II may not always provide an adequate level of control even when the temperature at the time of application falls within the recommended range stated on the product’s label. To make the best use of temperature-sensitive products, I suggest that the current, single-value, economic treatment threshold be replaced with an economic treatment range. The limits for this range are specified by two pest density values. The lower limit is the usual pest density that triggers a treatment. The upper limit is the maximum pest density that one can expect to reduce to a level below the lower limit given the temperatures expected during the treatment period. When the actual pest density exceeds the upper limit, the product should not be recommended; or, a warning should be included indicating that acceptable control may not be achieved.     

Level of daily physical activity in individuals with COPD compared with healthy controls

Background

Persons with Chronic Obstructive Pulmonary Disease (COPD), performing some level of regular physical activity, have a lower risk of both COPD-related hospital admissions and mortality. COPD patients of all stages seem to benefit from exercise training programs, thereby improving with respect to both exercise tolerance and symptoms of dyspnea and fatigue. Physical inactivity, which becomes more severe with increasing age, is a point of concern in healthy older adults. COPD might worsen this scenario, but it is unclear to what degree. This literature review aims to present the extent of the impact of COPD on objectively-measured daily physical activity (DPA). The focus is on the extent of the impact that COPD has on duration, intensity, and counts of DPA, as well as whether the severity of the disease has an additional influence on DPA.

Results

A literature review was performed in the databases PubMed [MEDLINE], Picarta, PEDRO, ISI Web of Knowledge and Google scholar. After screening, 11 studies were identified as being relevant for comparison between COPD patients and healthy controls with respect to duration, intensity, and counts of DPA. Four more studies were found to be relevant to address the subject of the influence the severity of the disease may have on DPA. The average percentage of DPA of COPD patients vs. healthy control subjects for duration was 57%, for intensity 75%, and for activity counts 56%. Correlations of DPA and severity of the disease were low and/or not significant.

Conclusions

From the results of this review, it appears that patients with COPD have a significantly reduced duration, intensity, and counts of DPA when compared to healthy control subjects. The intensity of DPA seems to be less affected by COPD than duration and counts. Judging from the results, it seems that severity of COPD is not strongly correlated with level of DPA. Future research should focus in more detail on the relation between COPD and duration, intensity, and counts of DPA, as well as the effect of disease severity on DPA, so that these relations become more understandable.     

Two-component signal transduction in human fungal pathogens

Signal transduction pathways provide mechanisms for adaptation to stress conditions. One of the most studied of these pathways is the HOG1 MAP kinase pathway that in Saccharomyces cerevisiae is used to adapt cells to osmostress. The HOG1 MAPK has also been studied in Candida albicans, and more recently observations on the Hog1p functions have been described in two other human pathogens, Aspergillus fumigatus and Cryptococcus neoformans. The important, but not surprising, concept is that this pathway is used for different yet similar functions in each of these fungi, given their need to adapt to different environmental signals. Current studies of C. albicans focus upon the identification of two-component signal proteins that, in both C. albicans and S. cerevisiae, regulate the HOG1 MAPK. In C. albicans, these proteins regulate cell wall biosynthesis (and, therefore, adherence to host cells), osmotic and oxidant adaptation, white-opaque switching, morphogenesis, and virulence of the organism.