Inhibitory effect of tea flavonoids on the ability of cells to oxidize low density lipoprotein.

Dietary flavonoid intake has been reported to be inversely related to mortality from coronary heart disease, and the anti-atherosclerotic effect of flavonoids is considered to be due probably to their antioxidant properties. Oxidation of low density lipoprotein (LDL) has been reported to be induced by the constituent cells of the arterial wall. Accordingly, we examined the effect of pretreatment with tea flavonoids, such as theaflavin digallate, on the ability of cells to oxidize LDL. Theaflavin digallate pretreatment of macrophages or endothelial cells reduced cell-mediated LDL oxidation in a concentration- (0-400 microM) and time- (0-4 hr) dependent manner. This inhibitory effect of flavonoids on cell-mediated LDL oxidation was in the order of theaflavin digallate > theaflavin > or = epigallocatechin gallate > epigallocatechin > gallic acid. Further, we investigated the mechanisms by which flavonoids inhibited cell-mediated LDL oxidation using macrophages and theaflavin digallate. Theaflavin digallate pretreatment decreased superoxide production of macrophages and chelated iron ions significantly. These results suggest that tea flavonoids attenuate the ability of the cell to oxidize LDL, probably by reducing superoxide production in cells and chelating iron ions.

Stable human calcitonin analogues with high potency on bone together with reduced anorectic and renal actions.

Various derivatives of human calcitonin have been synthesized and their biological characteristics compared with those of existing calcitonins. The acute effects of these analogues in reducing serum calcium levels and suppressing appetite were assessed in rats. A calcitonin analogue, PO-1 (CGNLSTCMLGKLSQELHKLQTYPQTAIGVGAP-NH2), having both the N- and C-terminal ten amino acid sequences those of human calcitonin, and the 12 amino acid central region that of salmon calcitonin, was found to have equal effectiveness with salmon calcitonin and elcatonin for reducing serum calcium levels. Strong hypocalcemic activity was also exhibited by PO-23 ([cyclo-Asp1, Lys7]-[des-Gly2]-[Leu8]-PO-1) and PO-29 ([Asp15, Asn17 , Phe19, His20]-PO-23). PO-23 was prepared by replacing the N-terminal Cys-Cys S-S bond of PO-1 with a ring structure composed of an Asp-Lys peptide bond to enhance physicochemical stability. PO-29 was prepared by modifying the central area of the PO-23 molecule to more closely mimic human calcitonin. When tested in vitro, human calcitonin analogues with a [cyclo-Asp1, Lys7] structure showed biological activities on osteoclast-like cells comparable to those of existing calcitonins (salmon calcitonin and elcatonin) in keeping with their relative potencies for in vivo hypocalcemic action. Acute anorectic activity in rats was strong with salmon calcitonin and elcatonin but relatively reduced with human calcitonin analogues having a [cyclo-Asp1, Lys7] structure. The activities of these analogues on kidney cells were also weaker than that of salmon calcitonin or elcatonin. These results suggest that stable human calcitonin analogues with a [cyclo-Asp1, Lys7] structure suppress bone resorption to a degree similar to that of salmon calcitonin or elcatonin with weaker activities on non-osseous tissues which might be related to adverse reaction.

Effect of supplementation with vitamin E on LDL oxidizability and prevention of atherosclerosis.

Supplementation of LDL with vitamin E is thought to protect LDL from oxidative modification and prevent the development of atherosclerosis. Large epidemiological studies have revealed that vitamin E levels in plasma are inversely correlated to the incidence of coronary heart disease. Double-blind placebo-controlled trials have reported that supplementation with vitamin E decreases the incidence of coronary events in coronary heart disease (CHD) patients. However, it is not clear how high a dose of vitamin E is needed to prevent formation of atherosclerosis. In animal studies, a diet containing 0.125% vitamin E increased its levels in plasma two-fold and prevented formation of early atherosclerotic lesions in the thoracic aorta of hypercholesterolemic rabbits. Dose-response studies in humans have reported that 400 IU/day vitamin E increased its levels in plasma two-fold and prolonged the lag time before LDL oxidation. It has been reported that oxidizability of LDL was correlated to the atherosclerotic score of coronary angiography in CHD patients. About 400 IU/day vitamin E, which increases its levels two-fold and prolongs sufficiently the lag time before LDL oxidation, might be beneficial in decreasing the individual risk of CHD.

Effects of the calcium ionophore A23187 on airway responsiveness to histamine and substance P in guinea pigs.

OBJECTIVE: We evaluated the mechanism of the airway hyperresponsiveness (AHR) induced by a calcium ionophore in guinea pigs. MATERIALS AND METHODS: Airway responsiveness to intravenous histamine (HS) and substance P (SP) was measured 24 h after a 1-h exposure to aerosolized A23187 (0.03 or 0.1 mg/ml) or its vehicle (10% DMSO). Changes were assessed by calculating -logPC350HS and logPC350SP. Neutral endopeptidase (NEP) activity in the airway tissues, as well as the nitrite (NO2) levels and the cell population in bronchoalveolar lavage fluid (BALF) was determined after measurement of pulmonary function. Changes in SP-induced vascular permeability 24 h after exposure to A23187 were measured by the Evans Blue dye extravasation technique. RESULTS: Exposure to A23187 caused a significant AHR to SP, along with a significant increase in the number of neutrophils and epithelial cells in the BALF. While there was no significant change in NEP activity in the airway tissues, the levels of nitrite in the BALF were significantly decreased in A23187-exposed animals. Significant correlations were found between the number of epithelial cells in the BALF and logPC350SP (r = 0.477, p < 0.05) and between nitrite levels in the BALF and -logPC350SP (r = 0.491, p < 0.05) A23187 exposure did not significantly change the SP-induced airway microvascular leakage. CONCLUSIONS: These data suggest that A23187 exposure induced AHR to SP possibly by reducing NO levels in the airway tissues. This may be due to damaged airway epithelium and/or NO breakdown by activated inflammatory cells in the airways of these guinea pigs.

[Effects of Onpi-to (TJ-8117) on mesangial injury induced by anti Thy-1 antibody].

We investigated the effect of Onpi-to (TJ-8117) on the mesangial injury induced by anti-Thy-1 antibody. TJ-8117 (400 mg/kg/day, p.o.) given from the 1st day (from the day of injection of the anti-thymocyte serum) or 4th day (after mesangial proliferation), markedly inhibited the mesangial proliferation and hypercellularity in glomeruli. TJ-8117 prevented the increase in the number of PCNA or ED-1 positive cells in glomeruli. These results suggest that TJ-8117 is effective against glomerular disease with mesangial injury.

The evaluation of therapeutic efficacy of hachimi-jio-gan (traditional Chinese medicine) to mouse hereditary cataract.

This study was of a series of the evaluation of Hachimi-Jio-Gan (Rehmannia Eight Formula, pa-wei-ti-huang-wan or Bawei dihuang wan) to the various cataracts. In this study, the drug was evaluated for its therapeutic efficacy to mouse hereditary cataract from the delay effect of cataract appearance age and the suppression rates of variation of some biochemical parameters. The dose of 200 mg of Hachimi-Jio-Gan/day/100 g of mouse body weight significantly delayed the cataract appearance age by 4 days as compared to that of non-treated group. We estimated that the delay effect of 4 days in mouse may be corresponded to 13.9 years, when it was converted into the case of human. This drug also suppressed variation of sodium and potassium ions level in the lens with cataractogenesis. Furthermore, the drug dramatically reactivated the sodium-potassium ATPase activity damaged with the cataract formation, and also had a slight action of reducing agent. From these facts, we presumed that the drug may have a prophylactic efficacy to the cataract caused by the inhibition of sodium-potassium ATPase activity and also the oxidation of lens protein.

The evaluation of therapeutic efficacy of hachimi-jio-gan (traditional Chinese medicine) to rat galactosemic cataract.

Hachimi-jio-gan (Rehmannia Eight Formula, pa-wei-ti-huang-wan or Bawei dihuang wan) is one of traditional Chinese medicines which has been used for treating various senile disease for a few hundred years. This drug was evaluated for its therapeutic efficacy to rat galactosemic cataract from the suppressive rate of variance of some biochemical parameters, whose variation with cataractogenesis or the advance of cataract have been reported already. The dose of 500mg of Hachimi-jio-gan/day/200g of rat body weight suppressed significantly the variations of hydration rate, Na/K ratios, and calcium ion level in the lens with the advance of galactosemic cataract, especially when the drug was administered by the pre- or concurrent-administration before or with 30% of galactose diet respectively. This drug also could delay the progressive rate of lens opacification. However, the drug had no effect to suppress the galactitol accumulation in the lens. From these results, we presume that a drug action of Hachimi-jio-gan may control the balance of sodium, potassium and calcium ions which are important in relation to the maintenance of lens transparency. Then, we realized, that this drug may have a prophylactic efficacy to diabetic cataract, though a more detail study should be needed to apply this drug to human cataract disease.

Sexual cyclicity and diurnal corticosterone secretion in rats given hypothalamic transection at two days of age.

Female rats given neural transection between suprachiasmatic and arcuate nuclei at 2 days of age showed regular sexual cyclicity and had ovarian corpora lutea. Thus, the ovarian activity seemed identical to that of intact or sham-operated control rats. However, the diurnal rhythm of the blood corticosterone concentration of the neonatally transected rats was not evident at 22 days of age, while it was already evident in controls. At 30 and 50 days of age, they had clear adrenal rhythms although the peak values were significantly lower than those of controls. Thus, the anterior connections of the medial basal hypothalamus, which are necessary for both cyclic gonadotropin discharge and diurnal corticosterone secretion, are still plastic and not yet established at 2 days of age.