Annual trunk diameters and tree heights were measured in July after initial_girdling and regirdling in Eucommia ulmoides Oliv. And the percentages of fallen leaves in all leaves and burst buds in all buds were est...Annual trunk diameters and tree heights were measured in July after initial_girdling and regirdling in Eucommia ulmoides Oliv. And the percentages of fallen leaves in all leaves and burst buds in all buds were estimated respectively on every autumn or spring. The results indicated that although the tree growth slowed down in the first year after girdling, but in the second year after girdling, the growth of the girdled trees tended to become normalized and up to the third year, it was similar to that of the normal trees. According to its developmental trait after girdling, the authors suggested that optimal girdling of the trees is in every 4 or 5 year intervals. With this method it was able to improve bark production and to protect the resource from extinction as well.展开更多
AIM: The mechanism of decreased vascular reactivity to vasoconstrictors in portal hypertension is still unclear. In addition to nitric oxide, defects in post-receptor signal transduction pathway have been suggested to...AIM: The mechanism of decreased vascular reactivity to vasoconstrictors in portal hypertension is still unclear. In addition to nitric oxide, defects in post-receptor signal transduction pathway have been suggested to play a role.However, substantial evidences observed equivocal changes of vascular reactivity following different agonists that challenged the hypothesis of the post-receptor defect. The current study was to evaluate the vascular reactivity to different agonists and the inositol trisphosphate (IP3)changes in signal transduction cascade from cirrhotic rats with portal hypertension.METHODS: The endothelial denuded aortic rings from cirrhotic and sham-operated rats were obtained for ex vivo tension study and measurement of the corresponding [3H] IP3 formation following different receptor and nonreceptor-mediated agonists' stimulation. Additionally,iNOS protein expression was measured in thoracic aorta.The contractile response curves to phenylephrine were performed in endothelial denuded aortic rings with and without preincubation with a specific iNOS inhibitor (L-N (6)-(1-iminoethyl)-lysine, L-NIL).RESULTS: In endothelial denuded aortic rings of cirrhotic rats, the vascular responses were reduced with phenylephrine and arginine vasopressin (AVP) stimulation but were normal with U-46619, NaF/AlCl3, and phorbol esterdibutyrate (PdBU) stimulation. Compared to the corresponding control groups, the degree of the increment of [3H] IP3 formation from basal level was also decreased with phenylephrine and AVP stimulation, but was normal with U-46619 and NaF/AlCl3 stimulation. The preincubation with L-NIL did not modify the hyporesponsiveness to phenylephrine. Additionally, the iNOS protein expression in thoracic aorta was not different in cirrhotic and shamoperated rats.CONCLUSION: Without the influence of nitric oxide, vascular hyporeactivity to vasoconstrictors persisted in cirrhotic rats with portal hypertension. However, the decreased vascular reactivity is an agonist-specific phenomenon. In addition,G-protein and phospholipase C pathway associated with the IP3 productions may be intact in cirrhotic rats with portal hypertension.展开更多
The aim of this study was to determine the susceptibility, intensity and distribution of pine trees to bark stripping by chacma baboons Papio ursinus in three plantations in the Eastern Highlands of Zimbabwe. The numb...The aim of this study was to determine the susceptibility, intensity and distribution of pine trees to bark stripping by chacma baboons Papio ursinus in three plantations in the Eastern Highlands of Zimbabwe. The number of plots/ha, stripped trees/ plot and stripped trees/ha was recorded during the pre-rainy, rainy and post-rainy seasons from August 2006 to May 2007. During data collection, altitude, aspect, season and other site predictor variables （e. g., roads and fire traces, water points, indigenous vegetation conservation areas, crop felds, human settlements, wattle scrubs, rocky areas, open grasslands, earlier stripped sites and roost sites） were recorded for each plot in association with selected predictor variables within plantation estates. Data on the number of stripped plots/ha, stripped trees/plot and stripped trees/ha were analysed as dependent variables using the Generalised Linear Model （GLM） through SPSS version 15 （2006） to determine which predictor variables were significantly related to bark stripping. Differences between means were tested using Bonferroni tests with a 5 % level of significance. Our findings show that bark stripping of pine trees by baboons occurred at all altitudes and aspects. Overall, the number of bark stripped trees/ha did not significandy vary by season. The number of bark stripped plots/ha was lower during the pre-rainy season than the rainy season, whereas the number of bark stripped trees/plot was higher during the pre-rainy than the rainy season. Bark stripping of pines occurred more often in the vicinities of areas with abundant food and water展开更多
文摘Annual trunk diameters and tree heights were measured in July after initial_girdling and regirdling in Eucommia ulmoides Oliv. And the percentages of fallen leaves in all leaves and burst buds in all buds were estimated respectively on every autumn or spring. The results indicated that although the tree growth slowed down in the first year after girdling, but in the second year after girdling, the growth of the girdled trees tended to become normalized and up to the third year, it was similar to that of the normal trees. According to its developmental trait after girdling, the authors suggested that optimal girdling of the trees is in every 4 or 5 year intervals. With this method it was able to improve bark production and to protect the resource from extinction as well.
基金Supported by the National Science Council of Taiwan, No. NSC91-2314-B-075-129 and the Taipei Veterans General Hospital of Taiwan,China, No. VGH91-28
文摘AIM: The mechanism of decreased vascular reactivity to vasoconstrictors in portal hypertension is still unclear. In addition to nitric oxide, defects in post-receptor signal transduction pathway have been suggested to play a role.However, substantial evidences observed equivocal changes of vascular reactivity following different agonists that challenged the hypothesis of the post-receptor defect. The current study was to evaluate the vascular reactivity to different agonists and the inositol trisphosphate (IP3)changes in signal transduction cascade from cirrhotic rats with portal hypertension.METHODS: The endothelial denuded aortic rings from cirrhotic and sham-operated rats were obtained for ex vivo tension study and measurement of the corresponding [3H] IP3 formation following different receptor and nonreceptor-mediated agonists' stimulation. Additionally,iNOS protein expression was measured in thoracic aorta.The contractile response curves to phenylephrine were performed in endothelial denuded aortic rings with and without preincubation with a specific iNOS inhibitor (L-N (6)-(1-iminoethyl)-lysine, L-NIL).RESULTS: In endothelial denuded aortic rings of cirrhotic rats, the vascular responses were reduced with phenylephrine and arginine vasopressin (AVP) stimulation but were normal with U-46619, NaF/AlCl3, and phorbol esterdibutyrate (PdBU) stimulation. Compared to the corresponding control groups, the degree of the increment of [3H] IP3 formation from basal level was also decreased with phenylephrine and AVP stimulation, but was normal with U-46619 and NaF/AlCl3 stimulation. The preincubation with L-NIL did not modify the hyporesponsiveness to phenylephrine. Additionally, the iNOS protein expression in thoracic aorta was not different in cirrhotic and shamoperated rats.CONCLUSION: Without the influence of nitric oxide, vascular hyporeactivity to vasoconstrictors persisted in cirrhotic rats with portal hypertension. However, the decreased vascular reactivity is an agonist-specific phenomenon. In addition,G-protein and phospholipase C pathway associated with the IP3 productions may be intact in cirrhotic rats with portal hypertension.
基金funded by the African Forest Research network (AFORNET) Grant number 17/01/2005
文摘The aim of this study was to determine the susceptibility, intensity and distribution of pine trees to bark stripping by chacma baboons Papio ursinus in three plantations in the Eastern Highlands of Zimbabwe. The number of plots/ha, stripped trees/ plot and stripped trees/ha was recorded during the pre-rainy, rainy and post-rainy seasons from August 2006 to May 2007. During data collection, altitude, aspect, season and other site predictor variables （e. g., roads and fire traces, water points, indigenous vegetation conservation areas, crop felds, human settlements, wattle scrubs, rocky areas, open grasslands, earlier stripped sites and roost sites） were recorded for each plot in association with selected predictor variables within plantation estates. Data on the number of stripped plots/ha, stripped trees/plot and stripped trees/ha were analysed as dependent variables using the Generalised Linear Model （GLM） through SPSS version 15 （2006） to determine which predictor variables were significantly related to bark stripping. Differences between means were tested using Bonferroni tests with a 5 % level of significance. Our findings show that bark stripping of pine trees by baboons occurred at all altitudes and aspects. Overall, the number of bark stripped trees/ha did not significandy vary by season. The number of bark stripped plots/ha was lower during the pre-rainy season than the rainy season, whereas the number of bark stripped trees/plot was higher during the pre-rainy than the rainy season. Bark stripping of pines occurred more often in the vicinities of areas with abundant food and water
