Modeling the electric image produced by objects with complex impedance in weakly electric fish

Weakly electric fish generate an electric field around their body by electric organ discharge (EOD). By measuring the modulation of the electric field produced by an object in the field these fish are able to accurately locate an object. Theoretical and experimental studies have focused on the amplitude modulations of EODs produced by resistive objects. However, little is known about the phase modulations produced by objects with complex impedance. The fish must be able to detect changes in object impedance to discriminate between food and nonfood objects. To investigate the features of electric images produced by objects with complex impedance, we developed a model that can be used to map the electric field around the fish body. The present model allows us to calculate the spatial distribution of the amplitude and phase shift in an electric image. This is the first study to investigate the changes in amplitude and phase shift of electric images induced by objects with complex impedance in wave-type fish. Using the model, we show that the amplitude of the electric image exhibits a sigmoidal change as the capacitance and resistance of an object are increased. Similarly, the phase shift exhibits a significant change within the object capacitance range of 0.1–100 nF. We also show that the spatial distribution of the amplitude and phase shifts of the electric image resembles a “Mexican hat” in shape for varying object distances and sizes. The spatial distribution of the phase shift and the amplitude was dependent on the object distance and size. Changes in the skin capacitance were associated with a tradeoff relationship between the magnitude of the amplitude and phase shift of the electric image. The specific range of skin capacitance (1–100 nF) allows the receptor afferents to extract object features that are relevant to electrolocation. These results provide a useful basis for the study of the neural mechanisms by which weakly electric fish recognize object features such as distance, size, and impedance.     

Deep water stratification in deep caldera lakes Ikeda, Towada, Tazawa, Kuttara, Toya and Shikotsu

From six deep caldera lakes in Japan, namely lakes Ikeda, Towada, Tazawa, Toya, Kuttara and Shikotsu (in Japanese referred to as Ikedako, Towadako, Tazawako, Toyako, Kuttarako and Shikotsuko), fine resolution profiles of temperature, electrical conductivity, dissolved oxygen and pH have been measured. Measurements were conducted just after deep circulation from the end of March to the end of May 2005. Lake Ikeda and Lake Towada did not undergo a complete turnover. Both showed meromictic features with a clear interface separating the recirculated mixolimnion from the deeper monimolimnion. Lake Tazawa and Lake Toya showed a complete turnover in winter 2004/05, while in Lake Kuttara and Lake Shikotsu, a deep water body remained throughout winter due to pressure effects on the temperature of maximum density. Although these deep waters were never fully recycled into the mixolimnion, they presented themselves as well supplied with oxygen and well circulated within themselves. Where overturn had not been complete small gradients in the oxygen profile, pH profiles and electrical conductivity profiles could be detected. However only in Lake Towada were concentrations of dissolved substances and gradients high enough to have decisive impact on the circulation pattern.     

Nitric oxide mediates the effects of pulsed electromagnetic field stimulation on the osteoblast proliferation and differentiation.

The purpose of this research was to investigate whether the effects of pulsed electromagnetic field (PEMF) stimulation on the osteoblast proliferation and differentiation are mediated by the increase in the nitric oxide (NO, nitrogen monoxide) synthesis. The osteoblasts (MC3T3-E1 cell line) were cultured in the absence (-NMMA group) or in the presence (+NMMA group) of the NO synthase inhibitor L-NMMA. First, osteoblasts were subjected to PEMF stimulation (15 Hz and 0.6 mT) up to 15 days. The DNA content and the NO concentration in the conditioned medium were determined on the 3rd, 7th, and 15th days of culture. Following, osteoblasts were stimulated in the proliferation (P-NMMA and P+NMMA groups) or in the differentiation (D-NMMA and D+NMMA groups) stages of maturation, and the alkaline phosphatase (AlPase) activity was determined on the 15th day of culture for all groups. PEMF stimulation increased significantly the nitrite concentration in the -NMMA group on the 3rd, 7th, and 15th days of culture. However, this effect was partially blocked in the +NMMA group. The DNA content in the -NMMA group, but not in the +NMMA group, increased significantly on the 3rd and 7th days of culture. The AlPase activity in the P-NMMA and D-NMMA groups, but not in the P+NMMA and D+NMMA groups, also increased significantly. In conclusion, the PEMF stimulatory effects on the osteoblasts proliferation and differentiation were mediated by the increase in the NO synthesis.     

Vascular endothelial growth factor as a non-invasive marker of pulmonary vascular remodeling in patients with bronchitis-type of COPD

BackgroundSeveral studies have indicated that one of the most potent mediators involved in pulmonary vascular remodeling is vascular endothelial growth factor (VEGF). This study was designed to determine whether airway VEGF level reflects pulmonary vascular remodeling in patients with bronchitis-type of COPD.MethodsVEGF levels in induced sputum were examined in 23 control subjects (12 non-smokers and 11 ex-smokers) and 29 patients with bronchitis-type of COPD. All bronchitis-type patients performed exercise testing with right heart catheterization.ResultsThe mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance (PVR) after exercise were markedly increased in all bronchitis-type patients. However, both parameters after exercise with breathing of oxygen was significantly lower than in those with breathing of room air. To attenuate the effect of hypoxia-induced pulmonary vasoconstriction during exercise, we used the change in mPAP or PVR during exercise with breathing of oxygen as a parameter of pulmonary vascular remodeling. Change in mPAP was significantly correlated with VEGF level in induced sputum from patients with chronic bronchitis (r = 0.73, p = 0.0001). Moreover, change in PVR was also correlated with VEGF level in those patients (r = 0.57, p = 0.003).ConclusionA close correlation between magnitude of pulmonary hypertension with exercise and VEGF level in bronchitis-type patients could be observed. Therefore, these findings suggest the possibility that VEGF level in induced sputum is a non-invasive marker of pulmonary vascular remodeling in patients with bronchitis-type of COPD.     

Amazake made from sake cake and rice koji suppresses sebum content in differentiated hamster sebocytes and improves skin properties in humans

ABSTRACT

Amazake is a traditional Japanese health drink. Here, we examined the effects of amazake on skin in cells and humans. Treatment with sake cake or rice koji suppressed intracellular lipid accumulation in differentiated hamster sebocytes, likely through the reduced expression of peroxisome proliferator-activated receptor-gamma (PPARγ) mRNA. In double-blind, placebo-controlled trial, seventeen Japanese women ingested either amazake or placebo for 4 weeks. Ingestion of the amazake decreased the sebum content compared to the placebo. The questionnaires showed improvements in “face color,” “dark circles under the eyes,” “glossy hair,” and “waking up well”, only in the amazake. In accordance with the questionnaires, additional analysis revealed the change in the L* values under the eyes was statistically increased in the amazake compared to the placebo. These results indicate that amazake may decrease sebum content in cells and humans and increase the L* values under the eyes, with some additional beneficial effects in humans.     

Genetic Distances and Reconstruction of Phylogenetic Trees from Microsatellite DNA

Recently many investigators have used microsatellite DNA loci for studying the evolutionary relationships of closely related populations or species, and some authors proposed new genetic distance measures for this purpose. However, the efficiencies of these distance measures in obtaining the correct tree topology remains unclear. We therefore investigated the probability of obtaining the correct topology (P(C)) for these new distances as well as traditional distance measures by using computer simulation. We used both the infinite-allele model (IAM) and the stepwise mutation model (SMM), which seem to be appropriate for classical markers and microsatellite loci, respectively. The results show that in both the IAM and SMM CAVALLI-SFORZA and EDWARDS'' chord distance (D(C)) and NEI et al.''s D(A) distance generally show higher P(C) values than other distance measures, whether the bottleneck effect exists or not. For estimating evolutionary times, however, NEI''s standard distance and GOLDSTEIN et al.''s (δ μ)(2) are more appropriate than other distances. Microsatellite DNA seems to be very useful for clarifying the evolutionary relationships of closely related populations.     

Cellular interaction against autologous tumor cells between IL-2-cultured lymphocytes and fresh peripheral blood lymphocytes in patients with breast cancer given immuno-chemotherapy

In patients with Stage II or III breast cancer and in patients with liver metastases from breast cancer, we examined cellular interaction in the cytotoxicity against autologous tumor cells by interleukin-2(IL-2)-cultured lymphocytes (CL) and fresh peripheral blood lymphocytes (FPBL) treated with immunochemotherapy including OK-432 and cyclophosphamide. In flow cytometric analysis, CD8 + CD11b+ and CD16+ cells significantly decreased after immuno-chemotherapy in both groups of patients. A protocol study in Stage II or III breast cancer patients showed suppressive activity of FPBL on the cytotoxic activity of CL in 3/9 of the non-treatment group but no suppressive activity and enhancing activity in 3/7 in the immuno-chemotherapy group. Moreover, in 19 patients with liver metastases from breast cancer treated with immuno-chemotherapy including adoptive immunotherapy, FPBL in 6/19 showed enhancing activity, and in 8/19 suppressive activity in the lysis of autologous tumor cells. In assaysin vitro using autologous and allogeneic tumor cells, FPBL showed a partial specificity in cellular interaction against autologous tumor cells. CD4-depleted FPBL inhibited cytotoxicity of CL, while CD8-depleted FPBL enhanced cytotoxicity of CL in patients with liver metastases. These results suggest that immuno-chemotherapy eliminates the suppressive population in FPBL and may induce tumor regression if combined with adoptive immunotherapy using CL.Abbreviations IL-2 interleukin-2 - CL IL-2-cultured lymphocytes - FPBL fresh peripheral blood lymphocytes - AIT adoptive immunotherapy     

In Vitro Reconstitution of Anti-Sheep Erythrocyte Antibody Response of T Cell-Depleted Spleen Cells by Allogeneic T Cells or by Factors Derived from Them

Restoration of the impaired antibody response to sheep erythrocytes (SRBC) in cultures of mouse spleen cells, which were deprived of thymus-derived lymphocytes (T cells) by treatment with anti-mouse brain-associated θ (BAθ) antiserum and complement, was studied by adding a small portion of syngeneic or allogeneic normal spleen cells in vitro. Allogeneic spleen cells had a far greater effect than syngeneic spleen cells on the restoration, as far as the normal spleen cells added were able to recognize the alloantigens on the anti-BAθ serum-treated spleen cells (bone marrow-derived lymphocytes). Treatment of the allogeneic spleen cells with mitomycin C did not affect their activity in the restoration of the impaired antibody response. The possibility that the role of T cells in the antibody response to SRBC may be replaced by a nonspecific mediator derived from T cells reacting with allogeneic cells was proven by the finding that supernatant of the mixed allogeneic spleen cell cultures restored the impaired anti-SRBC antibody response of the T cell-depleted spleen cells. The effect of such culture supernatant on the restoration of the antibody response was greatest when it was added to the T cell-depleted spleen cell cultures one day after cultivation with SRBC, suggesting that the effectiveness may result from triggering of the proliferation and differentiation of antibody-forming cell precursors, which have already reacted with the antigen, to antibody-forming cells.     

Identification ofArmillaria species from hokkaido by analysis of the intergenic spacer (IGS) region of ribosomal DNA using PCR-RFLP

The intergenic spacer (IGS) region, which is located between the 3′ end of 26S ribosomal DNA (rDNA) and the 5′ end of 5S rDNA, of sixArmillaria species from Hokkaido was investigated using polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP). Restriction with onlyAlu I could distinguishA. mellea subsp.nipponica from the other species. WithAlu I andDde I,A. ostoyae andA. gallica could be distinguished from the other species. Digestion withAlu I resulted in two patterns (types A and B) ofA. singula and three patterns (types A, B, and C) ofA. jezoensis. One pattern (type B) of the former species and two patterns (types B and C) of the latter species were each different from those of the other species.Armillaria sinapina gave only oneAlu I digestion pattern, which was identical to that ofA. jezoensis (type A) andA. singula (type A). However, by digestion withDde I,A. singula (type A) could be distinguished fromA. jezoensis (type A) andA. sinapina.