Search

A prerequisite of calcium signaling is the maintenance of cytoplasmic free Ca(2+) within a narrow, sub-micromolar range, compatible with cell viability. A variety of stress inducing agents and drugs can lead to a disruption of calcium homeostasis with ensuing toxicity. Amiodarone, an anti-arrhythmic drug with broad range microbicidal effect, has been shown to trigger a calcium burst in the yeast Saccharomyces cerevisiae. Recently, we reported that amiodarone elicits a starvation response, blocks cell cycle progression at multiple stages and represses the transcription of cell cycle genes. Here, we examine the connections between Ca(2+)-calcineurin signaling, nutrient sensing and regulation of the cell cycle.

The antiarrhythmic drug amiodarone has fungicidal activity against a broad range of fungi. In Saccharomyces cerevisiae, it elicits an immediate influx of Ca(2+) followed by mitochondrial fragmentation and eventual cell death. To dissect the mechanism of its toxicity, we assessed the transcriptional response of S. cerevisiae to amiodarone by DNA microarray. Consistent with the drug-induced calcium burst, more than half of the differentially transcribed genes were induced by high levels of CaCl(2). Amiodarone also caused rapid nuclear accumulation of the calcineurin-regulated Crz1. The majority of genes induced by amiodarone within 10 min were involved in utilization of alternative carbon and nitrogen sources and in mobilizing energy reserves. The similarity to nutrient starvation responses seen in stationary phase cells, rapamycin treatment, and late stages of shift to diauxic conditions and nitrogen depletion suggests that amiodarone may interfere with nutrient sensing and regulatory networks. Transcription of a set of nutrient-responsive genes was affected by amiodarone but not CaCl(2), indicating that activation of the starvation response was independent of Ca(2+). Genes down-regulated by amiodarone were involved in all stages of cell cycle control. A moderate dose of amiodarone temporarily delayed cell cycle progression at G(1), S, and G(2)/M phases, with the Swe1-mediated delay in G(2)/M phase being most prominent in a calcineurin-dependent manner. Overall, the transcriptional responses to amiodarone revealed by this study were found to be distinct from other classes of antifungals, including the azole drugs, pointing toward a novel target pathway in combating fungal pathogenesis.

Objective: To investigate the neoplastic nature of fibrous dysplasia by molecular clonality approaches., Methods: Twenty-one cases of fibrous dysplasia were examined by clonality assays based on X-chromosomal inactivation mosiacism. Lesional and non-lesional tissues were microdissected from paraffin sections followed by DNA extraction. The DNA was predigested by HpaII or HhaI, and then amplified by nested PCR targeting phosphoglycerate kinase (PGK) and androgen receptor (AR) genes. Single nucleotide polymorphism (SNP) at the PGK locus was identified by incubation of the PCR products with Bst XI and agarose gel electrophoresis, and CAG repeat length polymorphism at AR locus was determined by denaturing polyacrylamide gel electrophoresis and visualized by silver staining., Results: Microscopically, all 21 cases showed characteristic features of fibrous dysplasia, including spindle fibrous cell proliferation and immature bone trabeculae at various proportions. DNA polymorphisms at AR locus and SNP of PGK gene were found in 15 of 21, and 4 of 21 cases, respectively. All 19 cases were monoclonal in nature. Two cases showed no polymorphism at either AR or PGK gene locus., Conclusions: Fibrous dysplasia is likely a clonal, neoplastic process. Additional studies of larger number of cases are needed for a definitive conclusion.

Aim: To observe the apoptosis of cells in rat corneal grafts at acute rejection phase and explore the effects of IL-1 receptor antagonist (IL-1ra) on cell apoptosis., Methods: The penetrating corneal transplantation model was established. Corneal grafting was divided into four groups, namely, normal Wistar rat control group (no grafting, group A), isograft (Wistar rat-->Wistar rat, group B), allograft (Wistar rat-->SD rat) with normal saline treatment (group C) and allograft (Wistar rat-->SD rat) with IL-1ra treatment (group D). Cell apoptosis in corneal grafts was detected by TUNEL staining at 7 d, 10 d and 14 d after transplantation, and an automatic image analyzer was used to analyze the results, which were expressed as positive unit (PU). The changes of cellular ultrastructure in corneal grafts were observed under transmission electron microscope., Results: (1)The average survival time of corneal grafts in C and D groups was (10.38+/-1.85) d and (13.56+/-1.94) d, respectively, with significant difference (P<0.01). (2)As compared with normal and non-rejected corneas, cell apoptosis and necrosis commonly existed in corneal grafts which rejection had occur. (3)In normal corneas, there were merely a very small number apoptotic cells in epithelial laminal, and apoptotic cells were found hardly in stromal laminal and endothelial cell layers. However, sporadic apoptotic cells were found in all layers of corneal grafts in B, C and D groups at 10 d after transplantation, the average PU being of no notably difference (P>0.05). Apoptosis obviously increased in nearby regions of wound and central area of corneal grafts in C and D groups, especially in C group. The apoptotic cells were distributed mainly in basal layer of epithelial cells and stroma of superficial layer., Conclusion: Cell apoptosis plays an important role in corneal graft rejection reaction. IL-1ra treatment can prolong the survival time of corneal grafts by means of suppression of cell apoptosis in corneal grafts.

Objective: To evaluate the clinical efficacy of Ganxian recipe (GXR) and lamivudine (LVD) in a two-year treatment of chronic hepatitis B (CHB)., Methods: One hundred and twenty patients with CHB were randomly divided into the combinedly treated group (combined group) of 40 CHB patients who were treated with GXR combined with LVD. Another 40 CHB patients were treated with LVD alone (WM group), and still another 40 CHB patients were treated with GXR alone (TCM group). All these cases were randomly controlled and observed for two years., Results: Comprehensive efficacy: Total effective rate of the combined group (complete response and partial response) was 92.5%, while that of the WM group was 67.5% and TCM group 57.5%, respectively, with the difference between them was significant (P < 0.01); after treatment, the hepatic functions (AST, ALT, SB) of the three groups were all reduced, and the reduction in the combined group was particularly significant in comparison with the WM group or TCM group, P < 0.05 or P < 0.01 respectively, suggesting that the effect in the combined group was better than that in the other two groups; the rate of tyrosine-methionine-aspartate-aspartate (YMDD) virus mutation: it was 7.5% in the combined group, 40.0% in the WM group, and 5.0% in the TCM group; liver fibrosis improvement parameter: after treatment, the results in the combined group got better than those in the other two groups., Conclusion: GXR could inhibit the appearance of YMDD after long-term application of LVD, and combined use has marked synergism.

Propionyl-CoA is an intermediate metabolite produced through a variety of pathways including thioesterification of propionate and catabolism of odd chain fatty acids and select amino acids. Previously, we found that disruption of the methylcitrate synthase gene, mcsA, which blocks propionyl-CoA utilization, as well as growth on propionate impaired production of several polyketides-molecules typically derived from acetyl-CoA and malonyl-CoA-including sterigmatocystin (ST), a potent carcinogen, and the conidiospore pigment. Here we describe three lines of evidence that demonstrate that excessive propionyl-CoA levels in the cell can inhibit polyketide synthesis. First, inactivation of a putative propionyl-CoA synthase, PcsA, which converts propionate to propionyl-CoA, restored polyketide production and reduced cellular propionyl-CoA content in a DeltamcsA background. Second, inactivation of the acetyl-CoA synthase, FacA, which is also involved in propionate utilization, restored polyketide production in the DeltamcsA background. Third, fungal growth on several compounds (e.g., heptadecanoic acid, isoleucine, and methionine) whose catabolism includes the formation of propionyl-CoA, were found to inhibit ST and conidiospore pigment production. These results demonstrate that excessive propionyl-CoA levels in the cell can inhibit polyketide synthesis.

Objective: To observe the roles of subconjunctival administration of interleukin-1 receptor antagonist (IL-1ra) promoting corneal graft survival in rat models of high-risk penetrating keratoplasty., Methods: Corneal vascularization was induced in 40 Sprague-Dawley rats (40 eyes) by passing 10-0 silk suture through the corneal stroma, and 30 of these rats received corneal grafts from Wistar rats to establish high-risk keratoplasty models and were divided into 3 groups to receive their respective treatment with IL-1ra eye drops (50 microg/ml), 1% CsA eye drops, administered 3 times a day, or no treatment. All the rats were treated by Tobra Dex eye drops and Tropicamid eye drops, 3 times a day for 14 consecutive days after the operation. During the 30-day observation, the survival of the grafts was recorded, and all the grafts were evaluated for signs of rejection., Results: The mean survival times (MST) of the grafts of the treatment groups with IL-1ra and CsA were 12.00+/-1.50 d and 10.44+/-1.13 d respectively, significantly longer than that in the untreated model group (8.00+/-1.25 d, t=0.00, P<0.01), and the difference in the MST between the 2 treatment groups was also significant (t=0.00, P<0.01)., Conclusion: Treatment with IL-1ra may significantly prolong high-risk corneal allograft survival.

Aspergillus nidulans produces the polyketide toxin sterigmatocystin (ST) of which the biosynthetic and pathway specific regulatory genes compose a stc gene cluster. A previous mutagenesis screen identified 23 mutants defective in production of ST. Five mutants constitute a single locus. Genetic complementation and sequencing analysis revealed the mutant locus to be mcsA encoding methylcitrate synthase that converts propionyl-CoA to methylcitrate. Feeding downstream products of methylcitrate synthase, methylcitrate and pyruvate, did not restore ST production in mcsA mutants, indicating that loss of methylcitrate cycle products is not the cause of the ST defect. However, propionate, a precursor for propionyl-CoA, inhibited ST production and induced transcription of mcsA in the wild type. Furthermore, propionate impaired formation of two polyketide spore pigments whereas overexpression of mcsA relieved inhibition of ST production by propionate. Transcription analyses revealed that disruption of mcsA did not affect expression of the specialized fatty acid synthase genes (stcJ and stcK) or polyketide synthase gene (stcA) required for formation of norsolorinic acid (NOR), the first stable intermediate in the ST biosynthetic pathway. Feeding studies showed that NOR but not hexanoic acid (the fatty acid produced by StcJ/StcK and primer unit of StcA) or malonate (source of the extender unit of StcA) restored ST production in the mcsA mutant. We hypothesize that excess buildup of propionyl-CoA in mcsA mutants interferes with polyketide synthase activity.

We reviewed the efficacy in all of excimer laser photorefractive keratectomy (PRK) for the correction of myopia with excessively thin central cornea. the postoperative uncorrected visual acuity recovered the preoperative best corrected visual acuity the 67 cases (118 corneas) reviewed,. Diopter regression rate was 16.95% ear, and the incidence of corneal haze was 35.59% s demonstrate that PRK is an effective and safe method for myopia with thin central cornea.