Ultrastructural study on acibenzolar-S-methyl-induced scab resistance in epidermal pectin layers of Japanese pear leaves.

The infection behavior of Japanese pear scab pathogen Venturia nashicola race 1 was studied ultrastructurally in acibenzolar-S-methyl (ASM)-pretreated susceptible Japanese pear (cv. Kousui) leaves to determine the mechanism of ASM-induced scab resistance. On ASM-pretreated leaf surfaces, the infection behavior (conidial germination and appressorial formation) was similar to that on distilled water (DW)-pretreated leaves prior to cuticle penetration by the pathogen. However, after penetration, differentiated behavior was found in epidermal pectin layers and middle lamellae of the ASM-pretreated leaves. Subcuticular hyphae in epidermal pectin layers and middle lamellae of ASM-pretreated pear leaves were observed at lower frequency than in DW-treated leaves. The results indicated that fungal growth was suppressed in ASM-pretreated pear leaves. In the pectin layers of ASM- and DW-pretreated leaves, some hyphae showed morphological modifications, which were used as criteria to judge collapse of hyphal cells, including plasmolysis, necrotic cytoplasm, and cell wall destruction. More hyphae had collapsed in ASM-pretreated leaves than in DW-treated ones. In addition, the cell walls of collapsed hyphae broke into numerous fibrous and amorphous pieces, suggesting that ASM-induced scab resistance might be associated with cell-wall-degrading enzymes from pear plants. In addition, results from morphometrical analysis suggested that the activity or production of pectin-degrading enzyme from hyphae were inhibited by ASM application when compared with DW treatment.

Potential and limitations of alum or zeolite addition to improve the performance of a submerged membrane bioreactor.

In this study, alum and natural zeolite were added to a submerged membrane bioreactor (MBR) not only to reduce membrane fouling but also to increase the removal of nitrogen and phosphorus. Alum addition reduced significantly the rising rate of suction pressure and also resulted in stable and better COD removal. Although phosphorus removal was more than 90% by chemical precipitation, nitrification inhibition was observed. With the addition of natural zeolite, membrane permeability was greatly enhanced by the formation of rigid floc that had lower specific resistance than that of the control activated sludge floc. In particular, the nitrification efficiency was over 95% even at N-shock loading due to the ion-exchange capacity of zeolite. The mechanisms for improved membrane permeability through alum or zeolite addition were discussed in detail.

Anti-fibrotic effects of a hot-water extract from Salvia miltiorrhiza roots on liver fibrosis induced by biliary obstruction in rats.

The anti-fibrotic effects of a hot-water extract form the traditional Chinese medicinal herb Salvia miltiorrhiza (Labiatae) on liver fibrosis induced by biliary obstruction was studied in rats. Liver fibrosis was induced in male Sprague-Dawley rats by bile duct ligation and scission (BDL). After surgery, the hot-water extract of S. miltiorrhiza roots (100 mg kg(-1), p.o.) was administered daily for 28 days. The concentrations of aspartate transaminase, alanine transaminase, alkaline phosphatase, total bilirubin and total cholesterol in serum and hydroxyproline and malondialdehyde contents in liver were significantly increased in BDL rats. Treatment with the extract of S. miltiorrhiza significantly reduced (P < 0.01) the serum aspartate transaminase, alanine transaminase, alkaline phosphatase, and total cholesterol concentrations in BDL rats. The liver hydroxyproline content in BDL rats treated with extract was also reduced to 68% of that in BDL control rats (P < 0.01). The liver malondialdehyde content in BDL rats treated with the extract was also reduced to 47% of that in BDL control rats (P < 0.01). The morphological characteristics of fibrotic livers were improved in BDL rats treated with extract. Immunohistochemical examination of fibrotic liver showed that the extract of S. miltiorrhiza markedly reduced protein expression of alpha-smooth muscle cell-like actin, which indicates that hepatic stellate cell activation was inhibited during liver fibrosis development. The results indicate that the hot-water extract of S. miltiorrhiza roots inhibits fibrosis and lipid peroxidation in rats with liver fibrosis induced by biliary obstruction.

Antifibrotic effect of Stephania tetrandra on experimental liver fibrosis induced by bile duct ligation and scission in rats.

We examined the antifibrotic effect of a methanol extract from Stephania tetrandra (ST) on experimental liver fibrosis. Liver fibrosis was induced by bile duct ligation and scission (BDL/S) in rats. In BDL/S rats, activity levels of aspartate transaminase (AST), alanine transaminse (ALT), alkaline phosphatase (ALP), concentration of total bilirubin in serum, and hydroxyproline content of the liver were significantly increased. The ST treatment (either 100 mg/kg/day or 200 mg/kg/day, p.o. for 4 weeks) in BDL/S rats reduced the serum AST, ALT and ALP activity levels significantly (p< 0.01). Similarly, when compared to the control group, the concentration of hydroxyproline in the livers of the BDL/S rats treated with 100mg or 200mg ST treated rats decreased by 40% and 33% respectively, when compared to the BDL/S control group (p<0.01). The morphological characteristics of fibrotic liver that were observed in the BDL/S control group, improved in the ST treated BDL/S group. In the fibrotic liver of BDL/S rats treated with ST, a marked reduction in the numbers of alpha smooth muscle cell actin positive stellate cells was observed. These results indicate that doses of either 100 or 200 mg/kg/day of methanol extract from S. tetrandra, had an antifibrotic effect in rats with liver fibrosis induced by bile duct ligation and scission.

Effect of tetrandrine on experimental hepatic fibrosis induced by bile duct ligation and scission in rats.

Tetrandrine, an alkaloid isolated from the Chinese medicinal herb Stephania tetrandra, has been shown to elicit antifibrotic effects in various cell types. In the present study, the effect of tetrandrine on liver fibrosis was investigated by using bile duct ligation and scission in rats as a model of hepatic fibrosis. Treatment with tetrandrine in fibrotic rats reduced serum aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase levels to 72%, 52% and 51% that of controls at 10 mg/kg/day, respectively. Liver hydroxyproline contents in tetrandrine-treated rats with bile duct ligation and scission were also reduced to 65% of that of control rats with bile duct ligation and scission at 10 mg/kg/day. The morphological characteristics of fibrotic liver, which appeared in control bile duct ligation and scission group, were improved in tetrandrine-treated bile duct ligation and scission group. We also examined the effect of tetrandrine on cultured rat hepatic stellate cells, which plays an important role in the pathogenesis of hepatic fibrosis, activation to investigate whether it could act mainly by direct action on rat hepatic fibroblastic cells. In cultured rat hepatic stellate cells, tetrandrine reduced DNA synthesis to 57% of control hepatic stellate cells at 10 microg/ml without affecting cell viability. Smooth muscle-alpha-actin expression, the phenotypic marker of activated hepatic stellate cells, was also decreased. We conclude that tetrandrine has an antifibrotic effect on liver fibrosis in rats induced by bile duct ligation and scission, indicating that it might exert a direct effect on rat hepatic stellate cells.

Antiplatelet and antithrombotic effects of a combination of ticlopidine and ginkgo biloba ext (EGb 761).

The antiplatelet and antithrombotic effects of the oral combination treatment of ticlopidine and Ginkgo biloba extract (EGb 761) were studied in normal and thrombosis-induced rats. The ex vivo inhibitory effect on ADP-induced platelet aggregation of a small dose of ticlopidine (50 mg/kg/day) in combination with EGb 761 (40 mg/kg/day) was comparable to a larger dose of only ticlopidine (200 mg/kg/day). Bleeding time was also prolonged by 150%. Thrombus weight was also consistently decreased by a combination of ticlopidine and EGb 761 in an arterio-venous shunt model at two doses of ticlopidine (50 mg/kg) plus EGb 761 (20 mg/kg) and ticlopidine (50 mg/kg) plus EGb 761 (40 mg/kg). A combinatory treatment in acute thrombosis model in mice also showed a higher recovery than a single treatment.

Receptor subtypes mediating spinal cardiovascular effects of angiotensin II in rat using losartan and PD 123319.

It has previously been shown in this laboratory that intrathecal administration of 10 microg of angiotensin II produces an increase in arterial pressure and heart rate. As two receptor subtypes of angiotensin II, termed AT1 and AT2, have been identified in central nervous tissue this study examines the effects of selective antagonists on the pressor and cardioacceleratory responses to intrathecal administration of 10 microg of angiotensin II to the ninth thoracic spinal cord. The two non-peptide antagonists were losartan (2-n-butyl-4-chloro-5-hydroxymethyl-1-[(2'-(1H)-tetrazol-5-yl)biph enyl-4-yl)methyl]imidazole), which is selective for the angiotensin AT1 receptor, and PD 123319 (1-[[4-(dimethylamino)-3-methylphenyl]methyl]-5-(diphenyacetyl)-4, 5,6,7-tetrahydro-1H-imidazo[4,5-c]pyridine-6-carboxylic acid, ditrifluoroacetate, dihydrate), which is selective for the angiotensin AT2 receptor. Intravenous administration of losartan blocked both pressor and cardioacceleratory effects of angiotensin II. Intrathecal administration of losartan blocked only the pressor effects, raising the possibility that block of the heart rate response was in the periphery. Intrathecal administration of PD 123319 blocked the pressor effect of angiotensin II but had no effect on the cardioacceleratory response. However, by itself the antagonist produced a transient increase in arterial pressure and a slower increase in heart rate. The data support the involvement of the angiotensin AT1 receptor in mediating the effects of exogenously administered angiotensin II but also indicate a possible role of angiotensin AT2 receptors at the spinal level.