Effect of regional alveolar hypoxia on permeability pulmonary edema formation in dogs

We studied the effects of regional alveolar hypoxia on permeability pulmonary edema formation. Anesthetized dogs had a bronchial divider placed so that the left lower lobe (LLL) could be ventilated with a hypoxic gas mixture (HGM) while the right lung was continuously ventilated with 100% O2. Bilateral permeability edema was induced with 0.05 ml/kg oleic acid and after 4 h of LLL ventilation with an HGM (n = 9) LLL gross weight was 161 +/- 13 (SE) g compared with 204 +/- 13 (SE) g (P less than 0.05) in the right lower lobe (RLL). Bloodless lobar water and dry weight were also significantly lower in the LLL as compared with the RLL of the study animals. In seven control animals in which the LLL fractional inspired concentration of O2 (FIO2) was 1.0 during permeability edema, there were no differences in gravimetric variables between LLL and RLL. In eight additional animals, pulmonary capillary pressure (Pc), measured by simultaneous occlusion of left pulmonary artery and vein, was not significantly different between LLL FIO2 of 1.0 and 0.05 either before or after pulmonary edema. We conclude that, in the presence of permeability pulmonary edema, regional alveolar hypoxia causes reduction in edema formation. The decreased edema formation during alveolar hypoxia is not due to a reduction in Pc.     

Molecular evidence for the rapid propagation of mouse t haplotypes from a single, recent, ancestral chromosome

Mouse t haplotypes are variant forms of chromosome 17 that exist at high frequencies in worldwide populations of two species of commensal mice. To determine both the relationship of t haplotypes to each other and the species within which they exist, 35 representative t haplotypes were analyzed by means of 10 independent molecular probes, including five DNA clones and five polypeptide spots identified by means of two- dimensional gel electrophoresis. All of the tested haplotypes were found to share restriction fragments and polypeptide spots that are absent in mice carrying wild-type forms of chromosome 17. This observation provides the first direct evidence that all of the known t haplotypes are descendents of a single ancestral chromosome. The absence of variation among t haplotypes could mean that this ancestral chromosome existed relatively recently, in which case it would be necessary to postulate introgressions of t haplotypes across species lines to explain their presence in both Mus domesticus and M. musculus. Alternatively, it is possible that the ancestral chromosome existed prior to the split between M. domesticus and M. musculus and that, by chance, our probes fail to detect polymorphisms that exist among the t haplotypes. A further result of our analysis is the characterization of a partial t haplotype in a wild population of Israeli mice.      

植物分类方法的文献计量分析

本文采用文献计量的方法,统计了我国植物分类学各分支学科的有关文献。并对各类文献数量和内容构成的变化进行了分析。     

Mutations in the GTP-binding site of GS alpha alter stimulation of adenylyl cyclase

Mutational replacements of specific residues in the GTP-binding pocket of the 21-kDa ras proteins (p21ras) reduce their GTPase activity. To test the possibility that the cognate regions of G protein alpha chains participate in GTP binding and hydrolysis, we compared signaling functions of normal and mutated alpha chains (termed alpha s) of Gs, the stimulatory regulator of adenylyl cyclase. alpha s chains were expressed in an alpha s-deficient S49 mouse lymphoma cell line, cyc-. alpha s in which leucine replaces glutamine 227 (corresponding to glutamine 61 of p21ras) constitutively activates adenylyl cyclase and reduces the kcat for GTP hydrolysis more than 100-fold. There is a smaller reduction in GTPase activity in another mutant in which valine replaces glycine 49 (corresponding to glycine 12 of p21ras). This mutant alpha s is a poor activator of adenylyl cyclase. Moreover, the glycine 49 protein, unlike normal alpha s, is not protected against tryptic cleavage by hydrolysis resistant GTP analogs; this finding suggests impairment of the mutant protein's ability to attain the active (GTP-bound) conformation. We conclude that alpha s residues near glutamine 227 and glycine 49 participate in binding and hydrolysis of GTP, although the GTP binding regions of alpha s and p21ras are not identical.     

Two engineered eglin c mutants potently and selectively inhibiting kexin or furin

Eglin c with mutants L45R and D42R at the P(1) and P(4) positions has been reported to become a stable inhibitor toward the proprotein convertases (PC), furin and kexin, with a K(i) of 2.3x10(-8) and 1.3x10(-10) M, respectively. The mutant was further engineered at the P(2)'-P(4)' positions to create a more potent and selective inhibitor for each enzyme. The residue Asp at P(1)' which is crucial for stabilizing the conformation of eglin c remained unchanged. The eglin c mutants cloned into the vector pGEX-2T and expressed in Escherichia coli (DH5alpha) were purified to homogeneity, and their inhibitory activities toward the purified recombinant furin and kexin were examined. The results showed that (1) Leu47 at P(2)' replaced with either a positively or negatively charged residue resulted in a decrease in inhibitory activities to both enzymes; (2) the replacement of Arg with Asp at P(3)' was favorable for inhibiting furin with a K(i) of 7.8 x 10(-9) M, but not for inhibiting kexin; (3) the replacement of Tyr with Glu at P(4)' increased the inhibitory activity to kexin with a K(i) of 3 x 10(-11) M, but was almost without any influence on furin inhibition. It was indicated that the inhibitory specificity of eglin c could be changed from inhibiting elastase to inhibiting PCs by site-directed mutation at the P positions, while the inhibitory selectivity to furin or kexin could be optimized by mutation at the P' positions.     

Microbial transformation of deoxyandrographolide and their inhibitory activity on LPS-induced NO production in RAW 264.7 macrophages

A series of analogues of deoxyandrographolide (1) transformed by Cunninghamella blakesleana AS 3.2004 were isolated and identified by spectral methods including 2D NMR. Among them, 3-oxo-17,19-dihydroxy-7,13-ent-labdadien-15,16-olide (9), 3-oxo-19-hydroxy-1,13-ent-labdadien-15,16-olide (16), 3-oxo-1β-hydroxy-14-deoxy-andrographolide (17) and 3-oxo-2β-hydroxy-14-deoxyandrographolide (18) are new compounds. And their structure-activity relationships (SAR) of inhibitory activity on LPS-induced NO production in RAW 264.7 macrophage cells were also discussed.     

Genomic sequencing and comparative analysis of Epstein-Barr virus genome isolated from primary nasopharyngeal carcinoma biopsy

Whether certain Epstein-Barr virus (EBV) strains are associated with pathogenesis of nasopharyngeal carcinoma (NPC) is still an unresolved question. In the present study, EBV genome contained in a primary NPC tumor biopsy was amplified by Polymerase Chain Reaction (PCR), and sequenced using next-generation (Illumina) and conventional dideoxy-DNA sequencing. The EBV genome, designated HKNPC1 (Genbank accession number JQ009376) is a type 1 EBV of approximately 171.5 kb. The virus appears to be a uniform strain in line with accepted monoclonal nature of EBV in NPC but is heterogeneous at 172 nucleotide positions. Phylogenetic analysis with the four published EBV strains, B95-8, AG876, GD1, and GD2, indicated HKNPC1 was more closely related to the Chinese NPC patient-derived strains, GD1 and GD2. HKNPC1 contains 1,589 single nucleotide variations (SNVs) and 132 insertions or deletions (indels) in comparison to the reference EBV sequence (accession number NC007605). When compared to AG876, a strain derived from Ghanaian Burkitt's lymphoma, we found 322 SNVs, of which 76 were non-synonymous SNVs and were shared amongst the Chinese GD1, GD2 and HKNPC1 isolates. We observed 88 non-synonymous SNVs shared only by HKNPC1 and GD2, the only other NPC tumor-derived strain reported thus far. Non-synonymous SNVs were mainly found in the latent, tegument and glycoprotein genes. The same point mutations were found in glycoprotein (BLLF1 and BALF4) genes of GD1, GD2 and HKNPC1 strains and might affect cell type specific binding. Variations in LMP1 and EBNA3B epitopes and mutations in Cp (11404 C>T) and Qp (50134 G>C) found in GD1, GD2 and HKNPC1 could potentially affect CD8(+) T cell recognition and latent gene expression pattern in NPC, respectively. In conclusion, we showed that whole genome sequencing of EBV in NPC may facilitate discovery of previously unknown variations of pathogenic significance.     

Expression of the c-Met Proto-Oncogene and Integrin α5β1 in Human Gastric Cardia Adenocarcinoma

The hepatocyte growth factor receptor c-Met, a receptor tyrosine kinase, and Integrin α5β1, one of the main ECM receptors of hepatocytes have been reported to play important roles in tumor growth by activating mitogenic signaling pathways. In human gastric cardia adenocarcinoma, however, expression of the c-Met and Integrin α5β1 have not been reported. Here we examined the mRNA levels and protein expressions of these two genes and their relationship in human normal gastric cardia mucosa and primary carcinomas. Quantitative real-time PCR was used to analyze the mRNA expression of both c-Met and Integrin α5β1. The relationship between c-Met and Integrin α5β1 expression and the histologic characteristics of tumors were studied. Western blot analysis was performed to investigate the presence of c-Met and Integrin α5β1. The expression patterns of c-Met and Integrin α5β1 in 45 frozen slides of cardia adenocarcinoma were identified by immunohistochemistry. Our results indicate that the expression of c-Met and of Integrin α5β1 was significantly associated with tumor differentiation, TNM, and metastasis via the lymphogenic route. A significant positive correlation was also found between c-Met and Integrin α5β1 mRNA expression, suggesting that expression of c-Met and Integrin α5β1 has mechanical significance in the early stages of human gastric cardia adenocarcinoma.     

Hepatitis B virus X protein activates the p38 mitogen-activated protein kinase pathway in dedifferentiated hepatocytes

Hepatitis B virus X protein (pX) is implicated in hepatocarcinogenesis by an unknown mechanism. Employing a cellular model linked to pX-mediated transformation, we investigated the role of the previously reported Stat3 activation by pX in hepatocyte transformation. Our model is composed of a differentiated hepatocyte (AML12) 3pX-1 cell line that undergoes pX-dependent transformation and a dedifferentiated hepatocyte (AML12) 4pX-1 cell line that does not exhibit transformation by pX. We report that pX-dependent Stat3 activation occurs only in non-pX-transforming 4pX-1 cells and conclude that Stat3 activation is not linked to pX-mediated transformation. Maximum Stat3 transactivation requires Ser727 phosphorylation, mediated by mitogenic pathway activation. Employing dominant negative mutants and inhibitors of mitogenic pathways, we demonstrate that maximum, pX-dependent Stat3 transactivation is inhibited by the p38 mitogen-activated protein kinase (MAPK)-specific inhibitor SB 203580. Using transient-transreporter and in vitro kinase assays, we demonstrate for the first time that pX activates the p38 MAPK pathway only in 4pX-1 cells. pX-mediated Stat3 and p38 MAPK activation is Ca(2+) and c-Src dependent, in agreement with the established cellular action of pX. Importantly, pX-dependent activation of p38 MAPK inactivates Cdc25C by phosphorylation of Ser216, thus initiating activation of the G(2)/M checkpoint, resulting in 4pX-1 cell growth retardation. Interestingly, pX expression in the less differentiated hepatocyte 4pX-1 cells activates signaling pathways known to be active in regenerating hepatocytes. These results suggest that pX expression in the infected liver effects distinct mitogenic pathway activation in less differentiated versus differentiated hepatocytes.     

利用SRAP和SSR分子标记检测分析29份棉花种质遗传完整性

利用SRAP和SSR分子标记检测29份棉花种质遗传完整性。结果表明,无论每一份不同更新发芽率水平繁殖后代的种质之间,还是每一份不同繁殖世代数种质之间,其等位基因频率差异不显著,也没有检测到稀有等位基因缺失的情况。本试验表明不同更新发芽率水平和繁殖世代数差异没有对棉花这种常异花授粉作物种质遗传完整性变化产生影响。