Neuroendocrine and clinical effects of transdermal 17β-estradiol in postmenopausal women

The neuroendocrine and clinical effects of transdermal 17β-estradiol (rated at 50 μg/day; TTS 50) were studied in 40 postmenopausal women; ten additional postmenopausal women did not receive any drugs. The changes in LH and rectal temperature induced by the infusion of the opioid antagonist naloxone (10 mg i.v. bolus plus 10 mg/h for 4 h) were used to evaluate the central activity of endogenous opioid peptides. TTS 50 increased opioid activity, as evidenced by the restoration of the LH response (P < 0.01) and the enhancement of the hypothermic effect (P < 0.05) of naloxone. A greater reduction in hot flushes was observed in TTS 50-treated subjects than in untreated women, with the maximal effect of TTS 50 achieved after 3 months of therapy. TTS 50 did not modify the concentrations of circulating lipids, glucose or liver enzymes but reduced the biochemical parameters indicative of bone reabsorption. Bone density of the distal radius significantly increased during TTS 50 (P < 0.02), reaching its maximum value after 6 months of therapy. Thereafter bone density declined, but more slowly than in untreated women.

Our data suggest that TTS 50 has marked neuroendocrine effects, that it diminishes the incidence of hot flushes and reduces bone demineralization. By contrast, it has a very little, if any, metabolic impact on the liver or on glucose and lipid metabolism.     

Regulation of gastrin release in the dog by α2-adrenoceptors

1 The purpose of the present study was to analyse the effects of the α₂-adrenoceptor agonist medetomidine and the antagonist yohimbine on gastrin release in conscious dogs. 2 Gastrin secretion was investigated under both basal conditions and stimulation by 2-deoxy-D-glucose, food or bombesin. 3 Basal gastrin under fasting conditions was significantly reduced by medetomidine and increased by yohimbine. 4 2-deoxy-D-glucose-induced gastrin increase was fully inhibited by medetomidine; this effect was antagonized by yohimbine. 5 Medetomidine significantly inhibited food-induced increase in plasma gastrin; under these conditions yohimbine was without effect per se, but significantly antagonized the inhibitory action of medetomidine. 6 Gastrin release induced by bombesin was not affected by medetomidine or yohimbine. 7 These results suggest that α₂-adrenoceptors play an inhibitory role under conditions in which gastrin release is mainly mediated through cholinergic and non-cholinergic nervous pathways; in contrast, they do not indicate the presence of α₂-adrenoceptors on G cells of the dog stomach.     

Staurosporine-induced apoptosis in Chang liver cells is associated with down-regulation of Bcl-2 and Bcl-XL

A potent inhibitor of serine/threonine kinases, staurosporine exerts antiproliferative and apoptotic effects in many cancer cells, although the exact mechanism of its action is still unclear. This study examines the effects of staurosporine on Chang liver cells, an immortalized non-tumor cell line, in comparison with those caused in HuH-6 and HepG2 cells, two human hepatoma cell lines. Our results provide evidence that staurosporine promotes apoptosis in Chang liver cells as observed by flow cytometric analysis and acridine orange/ethidium bromide staining. The effect appeared already after 8 h of treatment and increased with treatment time and dose. After 48 h of exposure to 200 nM staurosporine clear apoptotic signs were observed in about 50% of the cells. Western blotting analysis showed that in Chang liver cells staurosporine induced a marked decrease in the levels of the antiapoptotic factors Bcl-2 (-75%) and Bcl-XL (-50%). Staurosporine also caused loss of mitochondrial transmembrane potential, release of cytochrome c from mitochondria and activation of caspase-3. The involvement of caspases in staurosporine-induced cell death was also suggested by the observation that the addition of z-VAD-fmk, a general inhibitor of caspases, suppressed apoptosis. In HuH-6 and HepG2 cells treatment with staurosporine induced the arrest of cells in G2/M phase of cell cycle. This effect was not modified by z-VAD-fmk and was not accompanied by the appearance of biochemical signs of apoptosis. We conclude that staurosporine induced apoptosis in Chang liver cells by a mitochondria-caspase-dependent pathway which was closely correlated with a decrease in Bcl-2 and Bcl-XL levels, while in HuH-6 and HepG2 hepatoma cells the drug caused only an antiproliferative effect.     

Luminal surface microgeometry affects platelet adhesion in small-diameter synthetic grafts

One of the major problems when using small-diameter vascular grafts in arterial reconstruction is the development of platelet-rich thrombi as a consequence of blood contact with artificial surfaces. The degree of occlusion is certainly affected by the thrombogenicity of the internal surface that seems to play a key role in patency and long-term wound healing of grafts. In this study, the blood compatibility of Cardiothane (CA) vascular grafts was investigated. The CA material, a blend of polyurethane and polydimethylsiloxane that has shown relatively good physical and biocompatibility properties, was manufactured into vascular grafts by the instrument named "spray-machine". Grafts with different luminal surface porosity were produced using increasing CA concentrations by the "spray-machine" and the blood compatibility was evaluated in vitro by a circulation system in which the human blood was allowed to interact with the material in a well-controlled setting. The samples of circulating blood were collected at different times of circulation and platelet adhesion and activation were studied. Grafts with a highly porous luminal surface induced a lower adhesion and activation of platelets in vitro than the low-porosity ones. These results underlined the importance of the microgeometry of the graft luminal surface in the interaction with blood.     

Effects of white wine, Coke and water on basal and food-stimulated gastric acid secretion and gastrin release in the dog

The effects of three types of white wine (10% ethanol; pH 2.84-3.26), Coke (pH 2.45) and water (pH 8.03) on basal and food-stimulated gastric acid secretion in dogs were investigated. Water and Coke did not significantly modify acid secretion and gastrin release under basal conditions. By contrast, white wine or water +10% ethanol significantly increased acid secretion, with a tendency to elevate plasma gastrin concentrations. Acid secretion and gastrin release induced by a standard meal were not significantly modified by previous administration of Coke and water. In contrast, white wine and water +10% ethanol significantly increased food-stimulated total acid output, without changing plasma gastrin levels. It is concluded that Coke and water have only trivial effects on basal and on food-stimulated gastric acid secretion and gastrin release in the dog. The gastric stimulant effect of white wine is mainly related to its percentage of alcohol regardless of the slight differences in pH of the solutions.     

Development of the anatomical alteration of the cerebellar fissura prima

The development of the naturally occurring malformation of the cerebellar fissura prima was monitored in rats starting from 4 days of life to the adulthood. The first sign of the malformation was evident at 10 days of life and consisted of an interruption of the pia mater and the fusion of the external granular layers on the two sides of the fissura. Later, nests of apparently mature granule cells could be seen to be encircled by cells of the external granular layer and to be connected to the granule cell layer by thin bridges of cells. Calretinin immunoreactive fibers followed the bridges of cells to reach the ectopic masses of cells. Towards the end of histogenesis and in adult animals, brush cells and Golgi cells were present in the ectopic masses of granule cells. The latter appeared to contribute to the formation of normal glomeruli, as in the orthotopic granule cell layer. In addition, bundles of parallel fibers crossed the boundary between the molecular layers on the two side of the fissure, thus suggesting that parallel fibers can contact Purkinje cells of the opposite folium.     

Ultrastructural localization of calcium deposits in rat myocardium after loud noise exposure

In previous studies we demonstrated that loud noise exposure induces ultrastructural alterations in the rat myocardium together with an increase in noradrenergic activity and in mitochondrial calcium influx. To verify the causal relationship between myocardial calcium entry and ultrastructural alterations induced by loud noise, in the present study we coupled routine electron microscopy with cytochemistry specifically dedicated to visualize calcium accumulation (revealed as antimonate deposits). We observed that the ultrastructural alterations occurring in both atrium and ventricle after 12 h of noise exposure, were densely packed with antimonate deposits. In particular, enlargements of the sarcoplasmic reticulum and dilution of the mitochondrial matrix, observed during routine electron microscopy, were markedly positive for calcium accumulation when observed by using antimonate. The present data strongly suggest that calcium entry results in accumulation of this ion at myocardial subcellular level. Moreover, the present results joined with previous evidence indicate that calcium accumulation is the final common pathway responsible for noise-induced myocardial morphological alterations.     

Antipeptide monoclonal antibodies inhibit the binding of rabies virus glycoprotein and alpha-bungarotoxin to the nicotinic acetylcholine receptor

It has been reported that binding to muscle nicotinic acetylcholine receptor at the post-synaptic membrane is an important event of the rabies virus neurotropism. The binding site can be located within the 190-203 region of the virus glycoprotein sharing a high degree of homology with the "toxic loop" of the curare-mimetic snake neurotoxins. We have synthesized a tetradecapeptide corresponding to this glycoprotein region and used it, following conjugation with an immunogenic carrier to raise MAbs. We found that some MAbs raised against the peptide were able to recognize both the virus glycoprotein and the snake neurotoxin alpha-bungarotoxin; moreover, they can inhibit the binding of rabies virus glycoprotein and alpha-bungarotoxin to the nicotinic acetylcholine receptor extracted from the electric organs of Torpedo marmorata. On the basis of this cross-reactivity, we suggest that rabies virus glycoprotein and curare-mimetic snake neurotoxins share three-dimensionally similar structures in order to bind to the nicotinic cholinergic receptor. The potential use of the immunogenic properties of the peptide for the rational design of a synthetic vaccine against rabies is proposed.     

Molecular design, synthesis, and antiinflammatory activity of a series of beta-aminoxypropionic acids

Previous experimental and theoretical studies carried out on the mechanism of action of adrenergic drugs have shown that the (methyleneaminoxy)methyl moiety (C = NOCH2, MAOMM) can be considered as a "bioisostere" of an aryl group (Ar). On this basis, a series of substituted beta-aminoxypropionic acids (AOPAs) were synthesized as analogues of antiinflammatory arylacetic acids (ArAAs), in which the Ar portion is substituted by the MAOMM, with the aim of evaluating whether any antiinflammatory activity could be obtained from this class of drugs after the substitution of the Ar with the MAOMM. The antiinflammatory activity of the AOPAs synthesized was determined by carageenan-induced rat paw edema, using diclofenac as the reference drug. The pharmacological data showed that most of the AOPAs examined exhibit a significant antiinflammatory activity, which in the case of the (E)-3-(benzylideneaminoxy)propionic acid (7q) is very close to that of the reference drug. Structural and theoretical studies were carried out in order to compare the conformation and the molecular reactivity of the AOPAs with those of the ArAAs. Pharmacological results showed that the ArAAs also generally exhibit an antiinflammatory activity after the substitution of the Ar with the MAOMM, thus supporting the hypothesis of a bioisosterelike relationship between these two moieties in this class of NSAIDs.     

Effects of liquid and freeze-dried grapefruit juice on the pharmacokinetics of praziquantel and its metabolite 4'-hydroxy praziquantel in beagle dogs.

Grapefruit juice changes the pharmacokinetic parameters of a variety of drugs metabolized primarily by cytochrome P450 3A. In a three-phase crossover study, six male beagle dogs were administered 100 ml of water (control), 100 ml of commercial liquid grapefruit juice, or 10 g of freeze-dried grapefruit juice (equivalent to 100 ml of liquid grapefruit juice) with 100 ml of water, followed after 2 h by single oral dose of praziquantel (30 mg kg(-1)). After treatment, the dogs were sampled at different times. Determination of praziquantel and its metabolite 4'-hydroxy praziquantel (identified by GC/MS) was performed by HPLC. Liquid and freeze-dried grapefruit juice preadministration increased the C(max) of praziquantel about three-fold and the AUC 2.5- and 2.3-fold, respectively. The T(max) (0.75 h) was unaffected by liquid or freeze-dried grapefruit juice, while T(1/2) was 2.3- and 1.7-fold higher compared with controls. The amount of 4'-hydroxy praziquantel was also affected by both liquid and freeze-dried grapefruit juice administration: the AUC and C(max) increased four- and three-fold, respectively and the T(max) was significantly enhanced. These findings demonstrate that both freeze-dried grapefruit juice and commercial liquid grapefruit juice significantly increase plasma concentrations and T(1/2) of praziquantel in dogs.