Apoptosis in fresh and cryopreserved cardiac valves of pig samples

To analyse the influence of cold ischemic time (CIT) (2–24 h) and of cryopreservation (liquid phase) on the viability of the valvular fibroblasts and in the presence of apoptosis. Cardiac valves from 10 pigs were evaluated by anatomo-pathological study of the wall, muscle and leaflet. At the same time, the presence of cellular death due to apoptosis was investigated in two ways; directly on tissue by Apodetec system and by two-colour flow cytometry assay analyzing a suspension of fibroblast from valve leaflets using Anexina V and propidium iodure (PI). We established three groups of samples to compare different experimental conditions: 2 h of ischemia (group 1), 24 h of ischemia (group 2), and a programme of cryopreservation (−1°C/min) after 2 h of ischemia, followed by storage in liquid nitrogen during a week and thawing was performed (group 3). The analysis of viabilities showed slight differences between all three groups. The results indicated CIT of 24 h undergoing more structural affectation than CIT of 2 h. Flow cytometry analysis did not show important differences between groups; however cryopreserved samples (group 3) slightly less viability and a higher percentage of death by apoptosis than group 1 and 2 using flow cytometry. Apoptosis was confirmed on tissue from all valves but mainly in samples of group 2 and group 3. In summary, the viability of the valves in the case of ischemic times of 2 h, 24 h or after cryopreservation/thawing differs slightly. The death of the cells is mainly mediated by necrosis and not by apoptosis.     

Callus induction, somatic embryogenesis and organogenesis in Narcissus confusus: correlation between the state of differentiation and the content of galanthamine and related alkaloids

In vitro cultures from two strains of Narcissus confusus (Amaryllidaceae) initiated from mature seeds were screened for their ability to produce alkaloids. Protocols for callus induction, somatic embryogenesis and organogenesis were established. The alkaloid contents were determined by HPLC. Undifferentiated calli produced small amounts of galanthamine, which increased with the degree of tissue differentiation. Scanning electron micrographs of the cultures at different stages of development were made. Embryogenic friable calli were maintained in culture for more than 2 years, retaining a high regeneration capability. All regenerated plants showed normal morphological characteristics. Received: 20 August 1997 / Revision received: 20 December 1997 / Accepted: 1 February 1998     

Electricity generation from young landfill leachate in a microbial fuel cell with a new electrode material

This study aims at evaluating the performance of a two-chambered continuously fed microbial fuel cell with new Ti–TiO₂ electrodes for bioelectricity generation from young landfill leachate at varying strength of wastewater (1–50 COD g/L) and hydraulic retention time (HRT, 0.25–2 days). The COD removal efficiency in the MFC increased with time and reached 45 % at full-strength leachate (50 g/L COD) feeding. The current generation increased with increasing leachate strength and decreasing HRT up to organic loading rate of 100 g COD/L/day. The maximum current density throughout the study was 11 A/m² at HRT of 0.5 day and organic loading rate of 67 g COD/L/day. Coulombic efficiency (CE) decreased from 57 % at feed COD concentration of 1 g/L to less than 1 % when feed COD concentration was 50 g/L. Increase in OLR resulted in increase in power output but decrease in CE.     

Beneficial effects of dithiothreitol on relative levels of glutathione S-transferase activity and thiols in oocytes, and cell number, DNA fragmentation and allocation at the blastocyst stage in the mouse

We analyzed the effect of in vitro aging of mouse oocytes in the presence of dithiothreitol (DTT) on relative levels of glutathione S-transferase (GST) activity and thiols in oocytes, and cell number, DNA fragmentation and cellular allocation to the inner cell mass (ICM) and trophectoderm (TE) lineage at the blastocyst stage. Ovulated oocytes from gonadotropin primed hybrid female mice of 6-8 weeks of age were aged in vitro in the presence of 0, 5, 50, or 500 microM DTT for 6 hr prior to insemination. Relative levels of GST activity and thiols in oocytes were determined by confocal laser scanning microscopy, DNA fragmentation using a single-step TUNEL method, and cell allocation to the ICM and TE lineage by blastocyst staining with propidium iodide and Hoechst 33258. Non-aged oocytes exhibited higher relative levels of GST activity and thiols when compared to oocytes aged in the presence of 0, 5, and 50 microM DTT. Day 5 blastocysts from the 5, 50, and 500 microM DTT groups exhibited higher total number of cells, number of ICM cells, and ICM/TE ratio, but lower percentage of number of nuclei with DNA fragmentation/number of ICM cells than blastocyst from the 0 microM DTT group. These data show that DTT counteracts the negative effects of a post-ovulatory aging of mouse oocytes in vitro on relative levels of GST activity and thiols in oocytes, and percentage of number of nuclei with DNA fragmentation/number of ICM cells, total number of cells, number of ICM cells and ICM/TE ratio in Day 5 blastocysts.     

Contrasting Roles of Islet Resident Immunoregulatory Macrophages and Dendritic Cells in Experimental Autoimmune Type 1 Diabetes

The innate immune system critically shapes diabetogenic adaptive immunity during type 1 diabetes (T1D) pathogenesis. While the role of tissue-infiltrating monocyte-derived macrophages in T1D is well established, the role of their tissue-resident counterparts remains undefined. We now demonstrate that islet resident macrophages (IRMs) from non-autoimmune mice have an immunoregulatory phenotype and powerfully induce FoxP3+ Tregs in vitro. The immunoregulatory phenotype and function of IRMs is compromised by TLR4 activation in vitro. Moreover, as T1D approaches in NOD mice, the immunoregulatory phenotype of IRMs is diminished as is their relative abundance compared to immunostimulatory DCs. Our findings suggest that maintenance of IRM abundance and their immunoregulatory phenotype may constitute a novel therapeutic strategy to prevent and/or cure T1D.     

具有第Ⅲ类功能性反应的捕食者一食饵系统的定性分析

本文对具有第Ⅲ类功能性反应的捕食者一食饵系统作了较完整的定性分析,讨论了正平衡点的存在性和稳定性,得到了极限环的存在条件及稳定性定理,发展地运用了Ｐｏｉｎｃａｒé切性曲线法．     

COX-2 Inhibition Combined with Radiation Reduces Orthotopic Glioma Outgrowth by Targeting the Tumor Vasculature

Cyclooxygenase 2 (COX-2) inhibitors have been shown to enhance tumor''s response to radiation in several animal models. The strong association of COX-2 and angiogenesis suggests that the tumor vasculature may be involved in this process. The current study investigated whether treatment with the COX-2 inhibitor E-6087 could influence response to local radiation in orthotopically growing murine gliomas and aimed to analyze the involvement of the tumor vasculature. GL261 glioma cells were injected into the cerebrum of C57bl/6 mice. From day 7 after tumor cell injection, mice were treated with COX-2 inhibitor at 50 mg/kg i.p. every third day. Radiation consisted of three fractions of 2 Gy given daily from day 9 to day 11. Mice were killed at day 21. The COX-2 inhibitor significantly enhanced the response to radiation, reducing mean volume to 32% of tumors treated with radiation only. The combination treatment neither increased apoptosis of tumor cells or stromal cells nor affected tumor microvascular density. In vitro, E-6087 and its active metabolite did not affect clonogenic survival of GL261 cells or human umbilical vein endothelial cell after radiation. In vivo, however, there was a nonsignificant increase in Angiopoietin (Ang)-1 and Tie-2 mRNA levels and a decrease of Ang-2 mRNA levels after combination treatment. These changes coincided with a significant increase in α-smooth muscle actin-positive pericyte coverage of tumor vessels. In conclusion, the antitumor effect of radiation on murine intracranial glioma growth is augmented by combining with COX-2 inhibition. Our findings suggest an involvement of the tumor vasculature in the observed effects.