Cholesterol-lowering effect of policosanol on rabbits with hypercholesterolaemia induced by a wheat starch-casein diet.

The effect of policosanol, a mixture of high-molecular-weight aliphatic alcohols isolated from sugarcane wax, on casein-induced hypercholesterolaemia in rabbits was studied. When policosanol was administered by the oral route once daily for 30 d (50 mg/kg) the increases in plasma total cholesterol and LDL-cholesterol (LDC-C) were significantly reduced when compared with the control group. The incorporation of 3H2O into sterols in the liver was significantly depressed, suggesting inhibition of hepatic cholesterol biosynthesis. The oral administration of policosanol raised the rate of removal of 125I-labelled LDL from serum. Kinetic parameters calculated following injection of [125I]LDL showed than in casein-fed rabbits, the terminal half-life (t1/2) was significantly decreased after policosanol treatment. The hepatic LDL-binding activity was increased after policosanol administration which suggested that the enhanced clearance was due, at least in part, to increased receptor-mediated uptake of LDL by the liver. Considered together, these results suggest that policosanol can significantly reduce the increase of plasma LDL-C in rabbits fed on a wheat starch-casein diet by reducing cholesterol biosynthesis in the liver. Such an effect could account for the enhancement of LDL catabolism through the receptor-mediated pathway.

Possible cytoprotective mechanism in rats of D-002, an anti-ulcerogenic product isolated from beeswax.

D-002 is an anti-ulcerogenic product, isolated from beeswax, which consists of a well-defined mixture of higher primary aliphatic alcohols. It is highly effective against ethanol-induced ulcers. This study was designed to determine if D-002 shows cytoprotective properties on gastric mucosa in ethanol-induced ulcers. The involvement of endogenous prostaglandins in the protective effect of D-002 was also investigated. When a subulcerogenic dose of indomethacin (10 mg kg-1) was injected simultaneously with oral administration of ethanol, oral pre-treatment with D-002 (5-100 mg kg-1) partially inhibited the gastric protection. D-002 (5 and 25 mg kg-1) administered to normal rats significantly increased the soluble mucus content and also prevented its reduction in rats with ethanol-induced ulcers. In addition, D-002 administered at 5 and 25 mg kg-1 prevented the increase of vascular permeability induced by ethanol (60%) and reduced the concentration of thromboxane B2 (TXB2) in gastric mucosa of rats with ethanol-induced ulcers. These results support the hypothesis that the anti-ulcerogenic properties of D-002 could be related to a cytoprotective mechanism.

Anti-ulcer activity of higher primary alcohols of beeswax.

The anti-ulcer effects of a natural mixture of higher aliphatic primary alcohols, designated D-002, isolated from beeswax, were compared with those of cimetidine on indomethacin-, ethanol-, water-immersion-induced ulcers and on gastric secretion in rats. D-002 (25-50 mg kg-1 p.o.) was similar to cimetidine in dose-dependently reducing the duration of indomethacin-induced ulcers while also being effective in preventing ethanol-induced ulcers, which are not affected by cimetidine. On the other hand, D-002 (100 mg kg-1) moderately decreased the volume of gastric basal secretion in pylorus-ligated rats, but not the acidity. Nevertheless, it inhibited gastric ulcer induced by pylorus-ligation at doses (50 mg kg-1) that were ineffective in decreasing the volume. In addition, 100 mg kg-1 of D-002 prevented the formation of acute gastric ulcers induced in rats by water-immersion stress. The results demonstrate the anti-ulcer activity of the preparation in different experimental models suggesting its potential value for ulcer therapy.

Pharmacological screening of plant decoctions commonly used in Cuban folk medicine.

Pharmacological screening for cardiotonic, hypotensive or bronchodilator activities was performed on 50 plant species depending on their traditional medical use by the Cuban population. Eleven of these species may have promise as therapeutic agents, but additional preclinical pharmacological and toxicological studies are needed to establish their therapeutic effectiveness and safety in human disease.

Kerosene-induced asthma.

Clinical evaluation of 286 asthmatic women showed 15.5% of those who improved clinically had contact with kerosene, while 43.9% of those who failed to improve used kerosene as fuel for cooking. In 16 women the onset of asthma occurred soon after they began to use kerosene. Kerosene can cause and aggravate asthma.

Pharmacological study of Cymbopogon citratus leaves.

Cymbopogon citratus leaves are employed by the Cuban population as an antihypertensive and anti-inflammatory folk medicine. A 10% or 20% decoction of leaves was tested using arterial pressure in rats, urine production and carrageenan-induced edema in rats. The decoction showed some dose-related hypotensive effects given intravenously and some weak diuretic and anti-inflammatory effect when given orally.

Kerosene aerosol induces guinea-pig airway hyperreactivity to acetylcholine.

Kerosene aerosol (32.5 mg/l; 20 min), when administered to guinea pigs 1 h before exposure to acetylcholine (Ach), induced potentiation of cumulative dose-response curve of this agonist on isolated tracheal strips as well as a decrease of the lethal doses of Ach. This enhanced response was absent or greatly reduced when kerosene aerosol was administered to guinea pigs 24 h previously or just before Ach challenge. This airway hyperreactivity was also lacking when carbachol or histamine were used as spasmogens instead of Ach. Possible explanations of these results are discussed.

Disodium cromoglycate inhibits bronchoconstriction by kerosine aerosol in rabbits.

To determine whether or not disodium cromoglycate (DSCG) inhibits the bronchoconstriction induced by inhalation of kerosene aerosol in rabbits, we carried out a study in 31 normal rabbits which were divided into four groups. DSCG was administered through the tracheal cannula twenty minutes before exposure to kerosene aerosol. Twenty and forty milligrams of DSCG as total doses inhibited kerosene induced bronchoconstriction in large airways (RL), but 5 mg of drug did not have any effect. DSCG at any tested dose did not inhibit the decreased dynamic lung compliance (CL) which was observed after kerosene aerosol. Our findings suggest that DSCG at high dose inhibit the bronchoconstrictor effect of kerosene in large airways of rabbits.

Studies on the effects of kerosine aerosol on airways of rabbits.

The effects of kerosine aerosol inhalation at a mean concentration of 32.5 mg/L on spontaneously breathing rabbits as well as on artificially ventilated rabbits were studied. Kerosine aerosol inhalation by spontaneously breathing rabbits during 4 minutes elicited an increase in total pulmonary resistance (RT) by 38 +/- 15 percent of control value (p less than 0.05). After atropine injection (0.2 mg/kg. I.V.) there was an immediate decrease in RT which was not significantly different from the control value after either, 1 or 5 minutes administration. Kerosine aerosol inhalation during 9 minutes elicited an increase in tracheal resistance by 45.5 +/- 8.2 percent of control value in artificially ventilated normal rabbits, while in vagotomized ones the increase was only by 21.2 +/- 6.9 percent of control value (p less than 0.05). It is concluded that inhalation of kerosine by spontaneously breathing or artificially ventilated rabbits elicit an acute increase in airways resistance which is mainly reflex and mediated by parasympathetic pathways.