In situ synthesis of magnetic iron oxide nanoparticles in chitosan hydrogels as a reaction field: Effect of cross-linking density.

Magnetic iron oxides such as magnetite and γ-hematite have attracted considerable attention as thermoseeds for hyperthermia treatment because of their ability to generate heat under an alternating magnetic field. Control of the particle size and their combination with biocompatible polymers are expected to be beneficial for optimization of the nanoparticles. These processes can be accomplished through the synthesis of magnetite in gels, as the network structure of the polymer gel can control the grain growth of the magnetite. However, the effect of the cross-linking density of the gels remains unclear. In this study, we synthesized magnetic iron oxides in situ in chitosan hydrogels with different cross-linking densities and examined the crystalline structure and heat generation under alternating magnetic field. The crystalline phase and amount of magnetite were observed to be dependent on the cross-linking density of the gel, and the heat generation of the nanoparticles was governed by their crystalline structure and particle size rather than solely the amount of formed iron oxide.

Coffee consumption is inversely associated with depressive status in Japanese patients with type 2 diabetes.

Depression has been reported to be more prevalent among diabetic patients than non-diabetic individuals. Although depression and diabetes are causally and bi-directionally related, the influence of food intake frequency on depressive symptoms in diabetic patients has not been fully evaluated. This cross-sectional study analyzed data obtained from 89 patients with type 2 diabetes who completed self-administered questionnaires regarding food intake frequency, diabetic variables, physical activity and depressive states. The prevalence of a "definite" depressive state was 16.9%. The duration of diabetes, hemoglobin A1c levels, diabetic microvascular complications and physical activity levels were similar between depressed and non-depressed patients. Daily intakes of total lipids, n-6 polyunsaturated fatty acids and lipid energy ratios were significantly lower, and the carbohydrate energy ratio was significantly higher in depressed than in non-depressed patients. Coffee consumption was inversely associated with depressive symptoms, but no significant association was found between tea or green tea consumption and depressive symptoms. The logistic regression analysis showed that coffee consumption was an independent predictor of non-depressed status in diabetic patients. This might be due to biologically active compounds containing in coffee other than caffeine.

Evolution of hierarchical cytoplasmic inheritance in the plasmodial slime mold Physarum polycephalum.

A striking linear dominance relationship for uniparental mitochondrial transmission is known between many mating types of plasmodial slime mold Physarum polycephalum. We herein examine how such hierarchical cytoplasmic inheritance evolves in isogamous organisms with many self-incompatible mating types. We assume that a nuclear locus determines the mating type of gametes and that another nuclear locus controls the digestion of mitochondria DNAs (mtDNAs) of the recipient gamete after fusion. We then examine the coupled genetic dynamics for the evolution of self-incompatible mating types and biased mitochondrial transmission between them. In Physarum, a multiallelic nuclear locus matA controls both the mating type of the gametes and the selective elimination of the mtDNA in the zygotes. We theoretically examine two potential mechanisms that might be responsible for the preferential digestion of mitochondria in the zygote. In the first model, the preferential digestion of mitochondria is assumed to be the outcome of differential expression levels of a suppressor gene carried by each gamete (suppression-power model). In the second model (site-specific nuclease model), the digestion of mtDNAs is assumed to be due to their cleavage by a site-specific nuclease that cuts the mtDNA at unmethylated recognition sites. Also assumed is that the mtDNAs are methylated at the same recognition site prior to the fusion, thereby being protected against the nuclease of the same gamete, and that the suppressor alleles convey information for the recognition sequences of nuclease and methylase. In both models, we found that a linear dominance hierarchy evolves as a consequence of the buildup of a strong linkage disequilibrium between the mating-type locus and the suppressor locus, though it fails to evolve if the recombination rate between the two loci is larger than a threshold. This threshold recombination rate depends on the number of mating types and the degree of fitness reduction in the heteroplasmic zygotes. If the recombination rate is above the threshold, suppressor alleles are equally distributed in each mating type at evolutionary equilibrium. Based on the theoretical results of the site-specific nuclease model, we propose that a nested subsequence structure in the recognition sequence should underlie the linear dominance hierarchy of mitochondrial transmission.