大狼毒三萜类化学成分的研究

自大戟科(Euphorbiaceae)植物大狼毒(Euphorbia nematocypha Hand—Mazz)根的乙醇提取物的苯溶解部分,经20%AgNO₃硅胶层析,分离得到七个三萜类成分。根据光谱(IR,EIMS,¹H—NMR和¹³C—NMR)和化学方法,确定其中一个化合物为新化合物,命名为大狼毒醇(nematocyphol,Ⅳa),其它化合物为已知物:印度荆芥醇乙酸酯(nepehinol acetate Ⅰ),日尔曼醇乙酸酯(germanicol acetate Ⅱ),大戟醇(euphol,Ⅲ),蒲公英醇(taraxasterol,Ⅴa),24-亚甲基环阿尔廷醇(24-methylenecycloartanol,Ⅴa)和印度荆芥醇(nepehinol,Ⅶa)。这些化合物均为首次从大狼毒中得到。     

亮氨酸脑啡肽的电子结构及构效关系研究

对亮氨酸脑啡肽进行了量子化学(INDO)计算,研究其电子结构特征,讨论其活性部位、作用机理及构效关系。同吗啡和R31833进行了活性部位的电子结构与空间结构比较,推断它们的活性药效结构具有共同特点,与阿片受体相互作用时作用方式相同,作用部位有对应关系,因而具有相同的药理性质。     

Postoperative deep vein thrombosis in the Taiwanese Chinese population

Reports of the incidence of postoperative deep vein thrombosis in the Chinese population of Taiwan are few in the literature. Over a 3 year period, the fibrinogen degradation products test, the pulse volume recorder, and venography were used to study 220 patients undergoing major operations at the Veterans General Hospital in Taipei, Taiwan. Deep vein thrombosis was found in 17 patients (7.7 percent). A comparison of the three diagnostic methods showed that the sensitivities of the fibrinogen degradation products test and the pulse volume recorder were 56.3 percent and 93.7 percent, respectively; the specificities, 97.4 percent and 95.7 percent, respectively; and the accuracies, 85.5 percent and 95.5 percent, respectively. These results support the combined use of the fibrinogen degradation products test and the pulse volume recorder for screening and diagnosing deep vein thrombosis.     

Concomitant translocation of Puralpha with its binding proteins (PurBPs) from nuclei to cytoplasm during neuronal development

Two Puralpha-binding proteins (PurBPs) were found in nuclear extract from mouse brain during P4-P10 by the overlay assay. At P14, they were decreased significantly in nuclear extract and increased in the S3 fraction, indicating their dynamic translocation during development. Western blot analysis also demonstrated concomitant translocation of Puralpha with the PurBPs during P7-P14, when neuronal circuit proceeds. Immunocytochemical study with cultured hippocampal neurons from rat E18 confirmed that nuclear Puralpha was translocated to cytoplasm after plating for 7-14 days. These results suggest that spatiotemporal translocation of Puralpha with the PurBPs from nuclei to cytoplasm has a crucial role in neuronal development.     

Inhibitory actions of serotonin on glutamate release in dorsal medulla suppress systemic arterial pressure of cats

The role of serotonin and glutamate release in dorsal medulla (DM) for regulation of systemic arterial pressure (SAP) was examined with microdialysis and high performance liquid chromatograph in anesthetized cats. KCl-perfusion in DM increased serotonin and glutamate concentrations in DM. Perfusion of serotonin resulted in decreases in glutamate concentration and SAP. Perfusion of alaproclate, a serotonin reuptake inhibitor that produced an increase in serotonin concentration in DM, had the same results as perfusion of serotonin. In conclusion, serotonin and glutamate appeared to be tonically and endogenously released from nerve terminals in DM, and the decrease in SAP could be attributed to the decreased glutamate release resulting from inhibitory action of serotonin in DM. The putative roles of serotonin and glutamate in DM may be important in SAP regulation.     

Leptin effects on food and water intake in lines of chickens selected for high or low body weight

There is an association between autonomic nervous system output and obesity. The sympathetic nervous system stimulates lipid metabolism and regulates food intake and, hence, body weight. Leptin, produced by adipocytes in proportion to their size, has been shown to directly stimulate the satiety center. In the experiment reported here, food and water intake were compared after intracerebroventricular administration of human recombinant leptin to lines of chickens that had undergone divergent selection for over 45 generations from a common White Rock base population for high (HWS) or low (LWS) body weight at 8 weeks-of-age. Leptin caused a linear decrease in food intake in chickens from the LWS line whereas no effect was observed in those from the HWS line. The HWS chickens tended to have reduced water intake post leptin administration. Others reported that leptin decreased food intake in both broiler and Leghorn chickens. Leptin concentration in the central nervous system may not contribute directly to the difference of body weight between HWS and LWS chickens.     

Differential cardiovascular effects of pharmacological agents in chickens selected for high and low body weight.

This study was conducted to investigate whether there are differences in the autonomic nervous system function of chickens from lines selected for high (HWS) or low body weight (LWS). The cardiovascular response to various pharmacological agents was used as an indicator of autonomic nervous system response. Ten individuals from each line and sex were used in the study. Catheters were introduced into the left brachial artery and vein and connected to a MP100-BIOPAC system to record blood pressure and heart rate (HR). Chickens were injected with phenylephrine, atropine, propranolol, and tetraethylammonium chloride (TEAC). The LWS birds exhibited a greater increase in mean arterial blood pressure (MABP) and a lesser increase in HR than the HWS birds following atropine. The response to atropine showed a line and sex interaction in which male birds had a greater increase in HR than females and LWS females had a lower increase in HR than the HWS females. Injection of phenylephrine following pretreatment with atropine caused a baroreceptor reflex in which males showed a greater decrease in HR than females. In response to the beta-adrenergic receptor blocker propranolol, females displayed a greater decrease in MABP than males and LWS birds had a greater decrease in HR than HWS birds. In response to the autonomic ganglionic blocker TEAC, MABP and HR decreased equally in both lines. The percentage of adrenal and sympathetic impact on regulation of HR showed that LWS females required greater adrenal activity than those from the other subclasses. Although changes in HR and MABP ratios in response to phenylephrine were different between lines, these responses were not different when phenylephrine was given following atropine. This pattern of response suggested that HWS birds had greater parasympathetic nervous system activity in order to maintain cardiovascular function. These results demonstrate that selection for HWS or LWS has resulted in greater parasympathetic and sympathetic nervous system tone in birds from the HWS and LWS birds, respectively, and suggest that differences between the lines could be at the level of the chromaffin tissue in the adrenal gland.     

Immunoreactivity of CD10 and inhibin alpha in differentiating hemangioblastoma of central nervous system from metastatic clear cell renal cell carcinoma.

The differential diagnosis between hemangioblastoma of the central nervous system and metastatic clear cell renal cell carcinoma can be problematic, because they may share striking morphologic similarities. Since CD10 is expressed in clear cell renal cell carcinoma, while inhibin alpha is expressed in hemangioblastoma, we used CD10 and inhibin alpha (inhibin A) to study their possible use in the distinction of these two entities. A total of 22 cases of cerebellar hemangioblastoma, five cases of metastatic clear cell renal cell carcinoma to the central nervous system, and 16 primary cases of clear cell renal cell carcinoma were studied with immunohistochemical staining of both CD10 and inhibin A. All 22 cases of hemangioblastoma were immunonegative for CD10 in the stromal cells. In contrast, all five cases of metastatic clear cell renal cell carcinoma and 16 cases of primary clear cell renal cell carcinoma showed positive CD10 membranous staining. In all, 20 cases of hemangioblastoma (20/22, 91%) expressed inhibin A in the stromal cells. Two cases of primary clear cell renal cell carcinoma (2/16, 13%) and three cases of metastatic clear cell renal cell carcinoma (3/5, 60%) showed immunopositivity for inhibin A. In conclusion, in addition to the immunostaining of inhibin A, CD10 is a superior marker for distinguishing between a hemangioblastoma and a metastatic clear cell renal cell carcinoma.     

A Sequential splicing mechanism promotes selection of an optimal exon by repositioning a downstream 5' splice site in preprotachykinin pre-mRNA

To explore the structural basis of alternative splicing, we have analyzed the splicing of pre-mRNAs containing an optional exon, E4, from the preprotachykinin gene. This gene encodes substance P and related tachykinin peptides by alternative splicing of a common pre-mRNA. We have shown that alternative splicing of preprotachykinin pre-mRNA occurs by preferential skipping of optional E4. The competing mechanism that incorporates E4 into the final spliced RNA is constrained by an initial block to splicing of the immediate upstream intervening sequence (IVS), IVS3. This block is relieved by sequential splicing, in which the immediate downstream IVS4 is removed first. The structural change resulting from the first splicing event is directly responsible for activation of IVS3 splicing. This structural rearrangement replaces IVS4 sequences with E5 and its adjacent IVS5 sequences. To determine how this structural change promoted IVS3 splicing, we asked what structural change(s) would restore activity of IVS3 splicing-defective mutants. The most significant effect was observed by a 2-nucleotide substitution that converted the 5' splice site of E4 to an exact consensus match, GUAAGU. Exon 5 sequences alone were found not to promote splicing when present in one or multiple copies. However, when a 15-nucleotide segment of IVS5 containing GUAAGU was inserted into a splicing-defective mutant just downstream of the hybrid exon segment E4E5, splicing activity was recovered. Curiously, the 72-nucleotide L2 exon of adenovirus, without its associated 5' splice site, activates splicing when juxtaposed to E4. Models for the activation of splicing by an RNA structural change are discussed.