Particle size analysis of some water/oil/water multiple emulsions.

Particle size analysis gives useful information about the structure and stability of multiple emulsions, which are important characteristics of these systems. It also enables the observation of the growth process of particles dispersed in multiple emulsions, accordingly, the evolution of their dimension in time. The size of multiple particles in the seven water/oil/water (W/O/W) emulsions was determined by measuring the particles size observed during the microscopic examination. In order to describe the distribution of the size of multiple particles, the value of two parameters that define the particle size was calculated: the arithmetical mean diameter and the median diameter. The results of the particle size analysis in the seven multiple emulsions W/O/W studied are presented as histograms of the distribution density immediately, 1 and 3 months after the preparation of each emulsion, as well as by establishing the mean and the median diameter of particles. The comparative study of the distribution histograms and of the mean and median diameters of W/O/W multiple particles indicates that the prepared emulsions are fine and very fine dispersions, stable, and presenting a growth of the abovementioned diameters during the study.

Cytotoxic activity of the root extract from Myoschilos oblongum.

The crude methanolic root extract of Myoschilos oblongum exhibited a significant cytotoxic activity against PZ-HPV-7 human prostate cells. Furthermore, two esters of docosanol were isolated from the CH(2)Cl(2) extract.

Oligoethylene ester derivatives of ketoprofen, naproxen and diclofenac as oral prodrugs: a pharmacological evaluation.

Polyoxyethylene esters of ketoprofen (1a-e), naproxen (2a-e) and diclofenac (3a-e) were tested in vitro to determine their stability in pH 7.4 phosphate buffer and in simulated gastric fluid (pH 2.0 buffer) and their susceptibility in undergoing enzymatic cleavage in human plasma. Furthermore their in vivo antiinflammatory and analgesic activity and GI toxicity were evaluated in rodents. All the prodrugs showed a good stability both in pH 7.4 phosphate buffer and in pH 2.0 buffer. They were readily hydrolyzed by human plasma and, for each group of prodrugs, no significant difference in hydrolysis rate was observed as the length of the oligoethylene chain increased. Esters 1a-e, 2a-e and 3a-e showed an anti-inflammatory activity (expressed as inhibition percent of carrageenan-induced edema in the rat) similar to that of their respective parent drug although at higher doses. The results obtained in the writhing test in mice demonstrated that all the prodrugs tested exhibited, following acute administration, a good analgesic effect. Furthermore these esters were significantly less irritating to the gastric mucosa, although administered at doses higher than the respective parent drug.

Corneal toxicity of xylazine and clonidine, in combination with ketamine, in the rat.

PURPOSE: To compare the corneal toxicity of xylazine (XYL)/ketamine (KET) with that of clonidine (CLO)/KET in the rat, in the presence or not of the alpha(2)-adrenergic antagonist yohimbine (YOH). METHODS: XYL (10 mg/kg) and CLO (0.15 mg/kg) were administered subcutaneously in the rat in combination with KET (50 mg/kg), in the presence or not of YOH (2 mg/kg). RESULTS: The corneas immediately lost transparency and luster, but recovered within 120 min. By both light and electron microscopy, a marked stromal edema and alterations of all layers were observed. In addition, XYL/KET altered the permeability of the cornea as indicated by the augmented levels of (14)C-indomethacin, topically administered 30 min after the anesthetic combination. CONCLUSIONS: The mechanism of the corneal toxicity of XYL and CLO in the rat is unclear but we speculate that: (a) proptosis and inhibition of normal blinking did not play a major role because topical application of hyaluronic acid did not protect against it; corneal decompensation, edema and opacification could be due to (b) osmotic or (c) mechanical endothelial stress: the first resulting from the sudden increase of the glucose concentration in the aqueous humor due to the well-known inhibition of insulin release by alpha(2)-adrenergic agonists, and the second from the acute elevation of intraocular pressure caused by these alpha(2)-adrenergic mydriatics in the rat; (d) addition, XYL and CLO could act by directly interacting with local alpha(2)- or, possibly, alpha(1)-adrenergic receptors, whose function is still not clear but probably essential for corneal homeostasis.

Antimicrobial activity of Epilobium spp. extracts.

The antimicrobial activity of the Epilobium angustifolium, E. hirsutum, E. palustre, E. tetragonum and E. rosmarinifolium ethanolic extracts was studied in vitro on Gram-positive and Gram-negative bacteria, yeasts and fungi. The cytotoxicity of the extracts was also evaluated using the Artemia salina test. All the extracts showed antimicrobial activity in a range of concentrations between 10 and 650 microgml of dry extract. E. angustifolium and E. rosmarinifolium had the most broad spectrum of action inhibiting bacteria, yeasts and fungi. The extracts were devoid of toxicity on Artemia salina within the range of antimicrobial concentrations, suggesting that the action is selective on microorganisms.

Analgesic properties of Epilobium angustifolium, evaluated by the hot plate test and the writhing test.

The analgesic properties of Epilobium angustifolium (Ea), a plant containing flavonoids with anti-inflammatory activity, have not been sufficiently studied so far. Thus, we decided to evaluate, by the classical hot plate test and the writhing test, the analgesic effect of a dry extract of Ea obtained by evaporating a commercially available mother tincture. In the former assay, the effect of Ea (380 mg/kg) was slightly lower than that of morphine (10 mg/kg s.c.). In the writhing test, which is more sensitive for non-steroidal analgesics, the effect of Ea was already significant (P < 0.05) at 95 mg/kg while at doses > or = 190 mg/kg, its activity was similar to that of lysine acetylsalicylate (300 mg/kg). The LD50 of this dry extract of Ea was 1.4+/-0.1 g/kg. Further studies are necessary for the identification of the active principles and the elucidation of their mechanism of action.

Effect of the exposure to gentamicin and diltiazem on the permeability of model membranes.

Preliminary observations showed that the calcium-antagonist diltiazem enhances the 'in vitro' bactericidal action of the aminoglycoside gentamicin, especially against Gram-positive bacteria. To verify if a non-specific interaction of these two drugs with biomembranes may play a role in their synergic effect on bacterial cells, we have studied the effect of exposure to gentamicin, in the absence or presence of diltiazem, on the release of carboxyfluorescein (CF) trapped in phosphatidylcholine (PC) unilamellar vesicles (LUVs) used as model membranes. A significant leakage of trapped CF from PC LUVs was registered when liposomes were treated with gentamicin and diltiazem together, employed at doses (50 and 100 microg/ml, respectively) unable to affect CF release if applied alone; the combined effect of gentamicin and diltiazem was synergic and not cumulative. The present findings demonstrate that the simultaneous exposure to gentamicin and diltiazem may induce significant alterations in the permeability of phospholipid membranes and, so, very likely, in functional properties of bacterial membranes, targets of their action.

Anti-proliferative effect on a prostatic epithelial cell line (PZ-HPV-7) by Epilobium angustifolium L.

Symptomatic benign prostatic hyperplasia (BPH) is a common condition in elderly men and has a significant impact on their daily lives. The drugs prescribed for treatment include alpha1-blockers, 5-alpha-reductase inhibitors and plant preparations. Epilobium angustifolium L. is deemed to be helpful in BPH therapy, although there is less information regarding the mechanism of its biological activity. The present study evaluated the effect of E. angustifolium extract on human prostatic epithelial cells (PZ-HPV-7). The exposure to E. angustifolium extract induced a marked inhibition of cell growth in all tested conditions. The anti-proliferative effect observed in in vitro systems clearly indicates a biologically relevant effect of compounds present in the extract. Considering these results, the use in traditional medicine of E. angustifolium extract against BPH seems to be justified. However, further experimental studies are needed to determine the biochemical mechanism of the action and the clinical value of the E. angustifolium extract.

Modulation of DNA synthesis by muscarinic cholinergic receptors.

Acetylcholine muscarinic receptors are a family of five G-protein-coupled receptors widely distributed in the central nervous system and in peripheral organs. Activation of certain subtypes of muscarinic receptors (M1, M3, M5) has been found to modulate DNA synthesis in a number of cell types. In several cell types acetylcholine, by activating endogenous or transfected muscarinic receptors, can indeed elicit cell proliferation. In other cell types, however, or under different experimental conditions, activation of muscarinic receptors has no effect, or inhibits DNA synthesis. A large number of intracellular pathways are being investigated to define the mechanisms involved in these effects of muscarinic receptors; these include among others, phospholipase D, protein kinases C and mitogen-activated-protein kinases. The ability of acetylcholine to modulate DNA synthesis through muscarinic receptors may be relevant in the context of brain development and neoplastic growth.

Intracellular signal transduction pathways as targets for neurotoxicants.

The multiple cascades of signal transduction pathways that lead from receptors on the cell membrane to the nucleus, thus translating extracellular signals into changes in gene expression, may represent important targets for neurotoxic compounds. Among the biochemical steps and pathways that have been investigated are the metabolism of cyclic nucleotides, the formation of nitric oxide, the metabolism of membrane phospholipids, the activation of a multitude of protein kinases and the induction of transcription factors. This brief review will focus on the interactions of three known neurotoxicants, lead, ethanol and polychlorinated biphenyls, with signal transduction pathways, particularly the family of protein kinase C isozymes, and discusses how such effects may be involved in their neurotoxicity.

Analysis of lonidamine in rat serum and testis by high performance liquid chromatography.

A HPLC method for the determination of lonidamine in serum and testis, suitable for pharmacological studies in the rat and other mammals, has been developed. Briefly, 0.5 mL of serum or about 0.2 g of testicular tissue were extracted with ethyl acetate and evaporated to dryness under nitrogen. The residue was redissolved in methanol and an aliquot was injected onto a C18 column eluted with a mobile phase consisting of acetonitrile:water (51:49, v/v), containing 0.1% trifluoroacetic acid. The eluate was monitored at 230 nm with a sensitivity of 0.05 AUFS. By this method, the pharmacokinetics and the serum and testicular levels of the drug up to 120 h after the administration of one single dose (100 mg/kg body weight) of lonidamine to Sprague-Dawley rats have been studied. Results were highly variable, as previously reported, but a very good linear correlation was found between the serum and the testicular levels, suggesting that, in the rat, and possibly in the human, testicular levels could be estimated based on the serum concentrations.

Effect of lonidamine on alpha2-macroglobulin, hemopexin and alpha1-antitrypsin in the rat testis and epididymis.

In a recent study (Leone et al., 2000) we reported that lonidamine (LND), an antispermatogenic drug, affected the concentration of selected testicular and epididymal proteins in the rat. Thus, the effect of LND on alpha2-macroglobulin (alpha2-M) and on other two acute phase proteins (APP), hemopexin (HPX) and alpha1-antitrypsin (alpha1-AT) was examined here. LND was administered orally at the dose of 100 mg/kg, the animals were killed after 24 and 48 hr and the samples were analyzed by immunoblotting. The drug did not induce any significant change of alpha2-M in the serum or testis and of HPX and alpha1-AT in the serum, testis or epididymis. Thus, the antispermatogenic action of LND was not accompanied by a significant change of these inflammatory markers, even if it did cause a decrease of alpha1-inhibitor-3, a negative APP, as previously reported (Leone et al., 2000).

Effects of lonidamine on testicular and epididymal proteins in the rat.

The mechanism responsible for the antispermatogenic activity of lonidamine (LND) [1-(2,4-dichlorobenzyl)-1H-indazole-3-carboxylic acid], a drug with low systemic toxicity and lack of significant hormonal effects, is still unclear but may be related to alterations of Sertoli cell proteins. Here, we confirmed that a single oral dose of LND (100 mg/kg b.w.) to sexually mature Sprague-Dawley rats causes shrinkage and weight reduction of the testes after 48 h. These macroscopic changes correlated with histologic alterations revealed by light microscopy, consistent with partially reversible inhibition of spermatogenesis. When the testes and the epididymides of animals treated with or without LND were homogenized and analyzed by the Bradford assay, a significant increase of total protein content was observed after 24 and 48 h. When these homogenates were analyzed by concanavalin blotting, specific changes of the major rat macroglobulins, i.e. alpha(1)-inhibitor-3, alpha(2)-macroglobulin, and alpha(1)-macroglobulin, were noted. In particular, LND caused a decrease of testicular alpha(1)-inhibitor-3, but not an increase of testicular alpha(2)-macroglobulin, indicating a mild local inflammatory response to the drug.

Ocular absorption and distribution of bendazac after topical administration to rabbits with different vehicles.

Ocular and systemic absorption of bendazac was investigated after topical administration to rabbits of 0.5% solutions of bendazac lysine in different polysaccharide vehicles. The results show that the drug is absorbed into the retina-choroid via an extracorneal, or sclero-conjunctival route; the iris and the ciliary body are presumably supplied via both the transcorneal and the extracorneal pathways. The extent of absorption via the extracorneal route is not related to vehicle viscosity but rather to the chemical features of vehicle. The transcorneal penetration appears to be hindered by the binding of the drug to corneal tissues.

Pumiliotoxin B-like alkaloid in extracts of the skin of the Australian myobatrachid frog Pseudophryne coriacea: effects on blood pressure and heart of the rabbit.

Extracts of the skin of the Australian myobatrachid frog Pseudophryne coriacea (PS) displayed striking, reversible and, in part, dose-dependent effects on the systemic blood pressure and the heart of the rabbit. Similarly to the results obtained in the rat, the blood pressure response in the rabbit consisted in an initial short-lasting fall, followed by a significant and persistent rise. The initial hypotensive effect was inhibited by atropine, indicating a cholinergic mechanism. The inhibition of the pressure rise by prazosin or guanethidine, but not by surrenalectomy or hexamethonium, suggests a catecholamine release from adrenergic nerve terminals of the vasculature. PS produced on the heart a variety of rhythm disorders, caused both by a release of acetylcholine and a direct effect on the myocardium. It is worth mentioning that tetrodotoxin, a typical sodium channel blocker, reduced or abolished the effects of PS both on the heart and the blood pressure, suggesting that sodium channels may directly or indirectly participate in the mechanism of action of PS.

A comparative study of behavioural and autonomic effects of atropine and Atropa belladonna.

Atropa belladonna L. (Solanaceae) tincture was compared with atropine for its anticholinergic activity, both in vivo and in vitro. In all tests, the biological activity of A. belladonna resulted greater than that suggested by its alkaloid content. The results suggest the presence in A. belladonna leaves of unknown compounds with a significant biological activity.

A comparative study of Atropa belladonna and atropine on an animal model of urinary retention.

The ability of Atropa belladonna L. and atropine to produce urinary retention has been studied in the rat. Our results suggest that A. belladonna is more effective than expected on the basis of its alkaloidic content.

Investigations on the ocular pharmacokinetics of bendazac in rabbits.

The ocular pharmacokinetics of bendazac were studied in rabbits, following intravenous administration of bendazac lysine. The compound and its 5-hydroxyderivative were determined in different eye compartments and plasma by radioassay, using [14C]bendazac, and HPLC. The highest concentrations were found in the iris and in descending order in the ciliary body, retina, cornea, tears, aqueous humor, vitreous, and lens. The time course of concentrations in the plasma, aqueous and vitreous humor, ciliary body, and retina showed kinetics described by the exponential equation y = aebx with a half-life of 2.47, 4.56, 3.59, and 3.22 hr, respectively; in the lens the half-life was 17.77 hr.