Meiosis resumption of canine oocytes cultured in the isolated oviduct.

The aim of this study was to investigate the effects of culture in isolated oviducts relative to meiotic maturation, the time required to resume meiosis and the viability of the canine oocytes. For this purpose, cumulus-oocyte complexes and isthmus-ampullar tracts of the oviducts were collected from bitches undergoing ovariohysterectomies and destined to two experiments of culture. In experiment 1, the oocytes were cultured for 24 or 30 h: (1) in 100 micro l drops under oil; (2) on the mucosal epithelium of the open oviducts; (3) in the ligated oviducts. In experiment 2, oocytes were cultured in the ligated oviduct for 24, 30 and 48 h. A group of control oocytes was not cultured (0 h). The results showed that within 30 h of culture, a higher proportion of oocytes (p < 0.001) resumed meiosis in the ligated oviduct (63.8%) than in drop (20.4%) or in the open oviduct (27.1%). Moreover, 24 and 30 h of culture assured higher proportions of meiosis resumption than 48 h (69.2 and 59.1% vs 35.8%, p < 0.005). Oocyte resumption of meiosis was mainly determined by oocytes at meiotic stages preceding metaphase I, while stages between metaphase I and II in the ligated oviduct ranged between 12.5 and 31.9%. The extension of the culture time up to 48 h in the oviduct increased oocyte degeneration significantly (59.3%, p < 0.0001) compared with 24 and 30 h (18.7 and 27.3%, respectively) and the oviductal epithelium showed nuclear picnosis and degeneration following culture. The present study suggests that the close physical interaction between the canine oocytes and the oviductal tract positively affects oocyte maturation, and meiosis is resumed within 30 h of culture. Moreover, the oocyte survival is better preserved within 30 h in the ligated oviduct compared with the conventional culture in drop or to the culture in the open oviduct, but the ligated oviduct does not assure viability of the oocytes up to 48 h of culture.

Effects of Dex-Verapamil on Doxorubicin cytotoxicity in P388 murine leukemia cells.

Resistance-modifying agents (RMAs) such as Verapamil have been proved to be effective in reversing multi-drug resistance (MDR) in many in vitro assays. In this study we have investigated the efficacy of Dex-Verapamil, the R-isomer of Verapamil, as a chemosensitizer in a murine leukemia cell line (P388) and in its resistant counterpart (P388/Dx) expressing a typical MDR phenotype. We have examined in vivo the effect of the co-administration of Dex-Verapamil and Doxorubicin in mice transplanted with P388 or P388/Dx cells. Mice treated with the combination of Doxorubicin plus RMA had a significant increase in survival rate as compared to controls; however, the effect was modest. On the contrary, in vitro Dex-Verapamil can enhance Doxorubicin cytotoxicity in P388/Dx cells with a much greater effect depending on the treatment scheme used, by increasing the intracellular content of drug. Taken together our data indicate that Dex-Verapamil can indeed increase the sensitivity to Doxorubicin in resistant cells, but the limited efficacy shown in vivo demonstrates that this phenomenon is strongly dependent on the treatment scheme used and on the maintenance of constantly elevated serum levels.

Tumour necrosis factor enhances the therapeutic effect of mitoxantrone in human ovarian cancer xenograft.

The combination of Tumour Necrosis Factor (TNF) and mitoxantrone was evaluated for potential chemotherapeutic effect against a human ovarian cancer cell line A2774 hetero-transplanted in female nude mice. Both antitumour efficacy (relative survival and reduction of ascites) and toxicity (weight loss and liver toxicity) of TNF alone, mitoxantrone alone or TNF + mitoxantrone were evaluated. A significant difference (P < 0.002) was observed only among animals bearing tumours treated with mitoxantrone (0.012 mg/Kg) + TNF (5 x 10(5) U/Kg) and controls. No cytotoxic effects were observed for this combination. These observations provide a rationale for further evaluation of TNF + mitoxantrone based regimes for the treatment of recurrent ovarian cancer.

Pharmacologic evaluation of the calcitonin analogue SB 205614 in models of osteoclastic bone resorption in vitro and in vivo: comparison with salmon calcitonin and elcatonin.

The activity of a novel calcitonin SB 205614 was compared with salmon calcitonin (sCT) and (Asu1,7)-eel calcitonin (ELC) in six different models of osteoclastic bone resorption in vitro and in vivo. SB 205614 is an ELC analogue that has an acetylenic bridge instead of the natural disulphide bridge, rendering the molecule more stable biologically than sCT and equally stable to ELC. Our aim was to determine whether this structural change compromised biologic activity, and if not, whether the increased stability could be used to exploit novel modes of administration. In the in vitro assays of pit formation by disaggregated rat osteoclasts on cortical bone slices (DROcA) and PTH stimulation of 45Ca-release from prelabeled fetal rat bone, no significant differences in activity were observed between the three calcitonins. In the DROcA, IC50s of 0.003, 0.015 and 0.064 pg/ml for sCT, ELC, and SB 205614, respectively, were determined, with total or near complete inhibition observed at 1 pg/ml (0.3 pM). In the assay of PTH-stimulation of 45Ca release, IC50s were measured of 5.5, 4.8, and 12.9 pM for sCT, ELC, and SB 205614, respectively; in every case maximal inhibition (ca. 80%) was observed at 30 and 100 pM. The internationally approved U.S. Pharmacopoeia bioassay of hypocalcemia in the rat following intravenous (IV) administration indicated that SB 205614 had a greater potency than ELC or sCT. More important, a full dose-hypocalcemic response curve demonstrated significantly increased potency compared to sCT or ELC, as the doses causing 15% lowering of serum calcium (approximately 50% of the maximum effect) were 33.9, 25.2, and 12.9 mg/kg for sCT, ELC, and SB 205614, respectively. As a preliminary means of investigating alternative delivery forms of calcitonin, the time course of the hypocalcemic effect was investigated in the rat and rabbit following IV administration, and was compared with that following intranasal (IN) administration (rat and rabbit), and following intracolonic administration (rat only). Maximal effects were similar, whereas in general the hypocalcemic effect of SB 205614 was of a longer duration than the other two calcitonins; this was reflected in a larger area over the curve (AOC). However, following IN administration in the rabbit, where an aerosol delivery device similar to that used in the clinic was used to administer the calcitonins, SB 205614 (100 IU/kg) induced a highly significant two-fold increase in the AOC compared to ELC or sCT. The calcitonins were also compared in assays designed to measure therapeutic efficacy in the rat.(ABSTRACT TRUNCATED AT 400 WORDS)

Influence of dietary manipulation on incidence of atopic disease in infants at risk.

Of 5,500 newborn infants whose family histories were screened, 900 were found to have anamnestic risk. Cord-blood IgE was evaluable in 4,677 of these newborns, of which 394 had levels > or = 1 IU/mL; 84 infants had both anamnestic risk and elevated cord-blood IgE levels. Parents of infants with anamnestic risk were informed of their child's risk of atopy. Additionally, for 391 infants at two of the three participating hospitals, a preventive diet was prescribed that recommended breastfeeding for the first 6 months of life, with maternal diet restricted to no more than 200 dL of cow milk per day, no more than one egg per week, and no tomato, fish, shellfish, nuts, or foods allergenic to the mother. Only soy formula was recommended, and introduction of solid foods was also carefully prescribed. Furthermore, doctors recommended against exposure to tobacco smoke, animal allergens, and early entrance into daycare. Evaluable infants whose parents complied with the prescribed diet were found to have a lower incidence of atopy during the first year of life (13.3%, n = 158) than infants whose parents had ignored the prescribed diet (54.7%, n = 86) or infants whose parents were offered no dietary recommendations (28.9%, n = 218). Differences between the compliant group and the two groups with unrestricted diets were significant, indicating that this prescribed diet may protect against or delay onset of food allergies during the first year of life.

Cyclic GABA-GABOB analogues. IV. Activity on learning and memory.

A number of N-substituted 4-hydroxy-, 4-acyloxy- and 4-alkoxy-2-pyrrolidinones were examined by a screening method predictive of their activity on cognitive processes. The 1-aminocarbonylmethyl-substituted compounds showed a favorable effect on learning and memory, and among them the most active was the 4-hydroxy derivative, oxiracetam, which had a potency considerably higher than piracetam, used for comparison purposes.

Experimental chronic epilepsy in rats: a screening method for antiepileptic drugs.

Rats were rendered epileptic by subpial injection of an FeCl3 solution. Epileptiform discharges, recorded by chronically implanted extradural electrodes, were evident within 48 h of surgery and persisted for more than 6 months. It is demonstrated that this model is useful for studying new antiepileptic agents since a series of clinically effective drugs (diazepam, clonazepam, Na phenobarbital, primidone, carbamezepine, ethosuximide, diphenylhydantoin, Na valproate, GABOB) show an activity which is does-dependent and within a range satisfactorily related to human dosages.