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A Lasserre

Publications and source records attributed to A Lasserre.

15 recordsLinked to original sources
PubMed2001

Regulation of lipid peroxidation by nitric oxide and PGF2alpha during luteal regression in rats.

Corpus luteum regression is related to an increased generation of reactive oxygen species. Although several studies indicate that PGF(2alpha) is involved in regression of the corpus luteum in mammalian species through an increase in reactive oxygen species, the exact mechanism remains unknown. In the present study, the relationship between nitric oxide and PGF(2alpha) in regulation of lipid peroxidation was studied. Ovarian tissue from pseudopregnant rats at mid- (day 5) or late phase or at the time of regression (day 9 of pseudopregnancy) of corpus luteum development was used. Thiobarbituric acid reactants, used as a lipid peroxidation index, were higher on day 9 of pseudopregnancy than on day 5. In contrast, glutathione content (an antioxidant metabolite) was lower on day 9 than on day 5 of pseudopregnancy. These results indicate that there was an enhanced oxidative status in ovarian tissue during luteolysis. Administration of N(omega)-nitro-L-arginine methyl ester (L-NAME: 600 micromol l(-1)), a competitive nitric oxide synthase (NOS) inhibitor, led to a decrease in basal thiobarbituric acid reactant content in ovarian tissue from rats on day 9 of pseudopregnancy only, indicating that during regression of the corpus luteum, NO could act as intermediary in ovarian lipid peroxidation. Administration of a luteolytic dose (3 microg kg(-1) body weight i.p.) of a synthetic PGF(2alpha) increased thiobarbituric acid reactant content in ovaries from rats on day 9 of pseudopregnancy. As this effect was reversed partially by L-NAME, it is proposed that during regression of corpora lutea, PGF(2alpha) and NO are involved in regulation of lipid peroxidation. As this effect was only reversed partially, it is possible that there is another mechanism involving PGF(2alpha) (but not the NO-NOS pathway) in regulation of ovarian lipid peroxidation. Furthermore, the administration of PGF(2alpha) enhanced ovarian NOS activity, whereas cyclooxygenase inhibition (by indomethacin treatment in vivo) reduced it. As western blotting of ovarian homogenates obtained from PGF(2alpha)-injected rats increased inducible NOS (iNOS) content, it is concluded that PGF(2alpha) enhances both activity and synthesis of NO in rat ovarian tissues during luteolysis. Taken together, these results indicate that in ovaries with regressing corpora lutea, both NO and PGF(2alpha) are involved in part in regulation of lipid peroxidation.

Animals↗
PubMed2000

Successful capacitation and homologous fertilization in vitro in Calomys musculinus and Calomys laucha (Rodentia - sigmodontinae).

Small South American rodents of the genus Calomys have been used extensively for virology and ecological research. Previous studies have demonstrated that Calomys musculinus and Calomys laucha have a relatively short oestrous cycle and that superovulation and parthenogenetic activation can be induced. The purpose of this study was to determine the requirements for in vitro manipulation of the male gamete and in vitro fertilization. Two culture media and different concentrations of spermatozoa were tested for their ability to support sperm motility, hyperactivation and the acrosome reaction. The ability of capacitated Calomys spermatozoa to penetrate zona-free hamster eggs was also evaluated. In vitro fertilization was assessed by examining attachment and binding to the zona pellucida, second polar body extrusion, pronucleus formation and the fertilizing sperm tail. The results of the study showed that: (i) Tyrode's albumin lactate pyruvate (TALP) medium was more effective than T6 medium for maintaining sperm motility in vitro; (ii) hyperactivation was achieved with TALP but not with T6; (iii) the acrosome reaction was easily distinguished by light microscopy and depends on time and sperm concentration; (iv) capacitated spermatozoa are able to penetrate zona-free hamster eggs; and (v) superovulated oocytes can be fertilized in vitro. This is the first report of capacitation and in vitro fertilization for Calomys sp. These results provide opportunities to use C. musculinus and C. laucha as new laboratory animals for research into reproductive biology.

Acrosome Reaction↗
PubMed1999

The kinetics of oocyte activation and dynamics of polar body formation in Calomys musculinus and Calomys laucha (Rodentia-Sigmodontinae).

The objective of this study was to determine whether Calomys laucha and Calomys musculinus superovulated oocytes undergo parthenogenetic activation following activation stimuli. Cumulus-intact or denuded oocytes were treated with medium containing ethanol (7%), medium containing strontium chloride, or medium alone. They were then incubated for 6-8 h to allow for activation. A group of oocytes was fixed immediately after maturation to serve as a control. The nuclear status of the oocytes was examined after staining with Hoechst 33342, to determine the timing of pronuclear progression from metaphase II to anaphase II or telophase II or to the pronuclear stage. The proportion of oocytes that underwent activation was higher for oocytes treated with ethanol or strontium chloride than in those incubated in medium alone, for the two species studied (p < 0.001). There was little evidence of spontaneous activation occurring in oocytes during the treatments. Most of the activated oocytes contained a single haploid pronucleus, but it was possible to find immediate cleavage and two pronuclei. The different classes of activated oocytes were cultured for 5 days. The type of activating treatment had a marked effect on the ability of the resulting C. musculinus and C. laucha parthenogenetic embryos to develop to the preimplantation stages. Incubation with ethanol produced only 8-cell embryos while the embryos induced with strontium chloride reached the blastocyst stage. This is the first report of parthenogenesis in C. musculinus and C. laucha. The ability of strontium ions to induce matured secondary oocytes to initiate parthenogenesis and obtain further development of Calomys provides opportunities to use Calomys oocytes in vitro and, therefore, to study the genetics, cell biology and virology of development.

Animals↗
PubMed1999

Superovulation in vesper mice, Calomys laucha--an important biomedical model for hantavirus and arenavirus (Rodentia-Sigmodontinae).

Sigmodontine rodents are poorly studied and have not received much attention as a reproductive model. Renewed interest in the South American rodents has been stimulated by their link to endemic diseases that are transmitted to man. Calomys laucha acts as a reservoir of two dangerous viruses: an arenavirus named 'Junin virus', the aetiological agent of Argentinian haemorrhagic fever, and the hantavirus, both of which constitute serious sanitary problems. The aim of this study was to establish suitable conditions to superovulate the vesper mouse, Calomys laucha. We examined the hormonal doses, the time interval between hormones, the time-course of ovulation, and the effect of female age on the response to exogenous hormone administration. Female mice were injected with 5-5, 8-8 or 12-15 IU of PMSG/hCG, 48 h apart, at different age intervals (from 30 to > 120 days old). The best superovulation rate was obtained with 8-8 IU PMSG/hCG. Ovulation started about 10 h post-hCG and was completed during the next 4-5 h, and was achieved irrespectively from the oestrus cycle stage. The number of oocytes was influenced by the age of the females. The youngest females had only a superovulatory response. Females older than 61 days showed both ovulatory and superovulatory responses, although 91-120-day-old females had a high ovulatory response. Most of the oocytes (96.5%) recovered were morphologically normal. The genus Calomys constitutes a reproductive model completely different from conventional laboratory rodents.

Aging↗
PubMed1998

Mouse oocyte quality and prostaglandin synthesis by cumulus oocyte complex after moderate chronic ethanol intake.

Chronic ingestion of ethanol produces a variety of effects on female reproductive function, depending on the dose and the exposure time but the mechanism of alcohol-induced ovarian failure has been little studied. Also the effects of chronic ethanol consumption on the oocyte quality in relation to morphological alterations and PGE synthesis by the oocyte cumulus complexes (OCCs) have not been described. In this study, immature female mice were treated with 10% ethanol in drinking water for 30 days. Then they were induced to superovulate, and at 14, 16 and 20 h post-hCG the quality of the ovarian and oviductal oocytes and PGE production by OCC was determined. At 14 h post-hCG, the percentage of oviductal immature oocytes was increased in the ethanol-treated females (P < 0.05). At 16 h post-hCG, the percent of oviductal activated oocytes was higher in the treated females (P < 0.05), and the ovarian immature oocytes were decreased as compared to the control females (P < 0.05). At 20 h post-hCG, the ethanol-treated females had higher percents of activated oocytes in the oviducts and in the ovaries (P < 0.05) with respect to the controls. PGE synthesis by OCCs, assessed by RIA, was decreased in the treated female mice (P < 0.001). In summary, moderate chronic ethanol treatment in immature female mice can produce morphologic abnormalities in the oocytes (high parthenogenetic activated rates) and altered PGE production in the OCCs.

Animals↗
PubMed1998

Superovulation in vesper mouse Calomys musculinus (Rodentia-Sigmodontinae).

Optimal conditions for pharmacological induction of ovulation of vesper mouse, Calomys musculinus, were analyzed. The best superovulation (a mean of about 21 eggs per female, range 12-45) was induced by the administration of 12 IU of PMSG followed 48 hr later by injection of 15 IU of hCG. Ovulation started about 10 hr after administration of hCG and was completed during the next 4-5 hr. The induction of ovulation was achieved irrespective of the stage of the oestrus cycle at the moment of PMSG administration. The majority of females (105, 82.7%) responded to the treatment with either an ovulatory (53.4%) or superovulatory (49.7%) response. Oocyte recovery and egg quality were clearly influenced by the age of females, 30 days to more than 120 days old. The majority (90.3%) of superovulated eggs was morphologically normal, and only a small proportion of eggs showed morphological abnormalities (7.4%) or were spontaneously activated (2.3%). Superovulated oocytes under these conditions, were able to undergo normal fertilization in vitro. After 6 hr of sperm-egg interaction in vitro, 87.5% of the oocytes had extruded the second polar body and/or developed pronuclei.

Age Factors↗
PubMed1998

Ceramic drug-delivery devices.

A variety of ceramics and delivery systems have been used to deliver chemicals, biologicals, and drugs at various rates for desired periods of time from different sites of implantation. In vitro and in vivo studies have shown that ceramics can successfully be used as drug-delivery devices. Matrices, inserts, reservoirs, cements, and particles have been used to deliver a large variety of therapeutic agents such as antibiotics, anticancer drugs, anticoagulants, analgesics, growth factors, hormones, steroids, and vaccines. In this article, the advantages and disadvantages of conventional drug-delivery systems and the different approaches used to deliver chemical and biological agents by means of ceramic systems will be reviewed.

Analgesics↗
PubMed1997

A zinc based self setting ceramic bone substitute for local delivery of testosterone.

Testosterone has been shown to stimulate bone healing. However, large doses of testosterone are associated with liver damage and prostate enlargement. Continuous release of testosterone at the traumatized bone site could enhance healing without inducing systemic side effects. In this investigation a self-setting zinc sulfate calcium phosphate (ZSCAP) ceramic with and without testosterone was used to fill experimentally induced bone defects in rats. Each treatment group consisted of six albino, Holtzman rats. Groups I and II consisted of non-operated and sham-operated animals. Rats in Group III, IV, V, and VI were implanted with ZSCAP particulate ceramic powders (63-75 microns) containing 0.0, 0.5, 1.0, or 1.5 mg testosterone in a 2.3 mm defect in the femur of each rat. Radiographic and morphologic examination of the implant site at four, eight, and twelve weeks post surgery showed integration of the implant in the femur of each rat. Serum testosterone of all rats was assayed at four, eight, and twelve weeks post surgery. Differences in the serum testosterone levels of rats in the six groups were not significant. Results of this study suggest that a ZSCAP-testosterone composite can be used to repair traumatized bone without increasing the levels of testosterone in the systemic circulation.

Animals↗
PubMed1997

A hydroxyapatite system for the continuous release of coumadin an anticoagulant.

Coumadin is an anticoagulant used in the treatment of patients with pulmonary thromboembolisms or those implanted with mechanical vascular devices. Its efficacy is complicated by side effects such as hemorrhaging. Administration of coumadin by the traditional routes of pills and injections causes wide fluctuations of the drug in plasma. Thus, experiments were conducted to develop a hydroxyapatite ceramic system for releasing coumadin in vivo continuously for 7-10 days. A series of preliminary in vivo experiments was conducted to determine an effective non-lethal therapeutic dosage of coumadin for rats. Homogenous matrices containing varying amounts of coumadin were implanted subcutaneously in rats and the blood clotting time was determined. Results of these experiments showed that one mg coumadin delivered from HA implants doubled the blood clotting time and did not induce fatal hemorrhage. Subsequent in vitro studies were conducted to determine the most efficient way to deliver coumadin at a slow and sustained rate. Results of these experiments suggested that a solid insert of one mg of compressed coumadin in a hydroxyapatite ceramic shell released the drug more slowly and efficiently than a homogenous matrix consisting of compressed coumadin and hydroxyapatite.

Animals↗
PubMed1997

In vitro and in vivo dapsone release from hydroxyapatite reservoirs.

Dapsone is a drug which is administered orally, on a daily basis, for four to five years as a cure for leprosy. The major problems associated with dapsone therapy include hemolysis, methemoglobinemia and patient non-compliance. Cimetidine reduces the side effects of dapsone and increases its levels in the blood. A ceramic drug delivery system was developed to maintain therapeutic levels of dapsone for an extended period of time and to alleviate associated side effects. In vitro release of commercial dapsone tablets (100 mg) and cimetidine pellets (400 mg) from hydroxyapatite reservoirs was studied in 100 ml absolute ethanol at 37 degrees C. Hydroxyapatite (HA) reservoirs loaded with one dapsone tablet released the drug at the rate of 8.3 mg/day for nine days, after which a much slower release occurred for another three days. With a load of two dapsone tablets, the rate of release was 6.7 mg/day for four weeks. HA reservoirs loaded with one cimetidine pellet delivered the drug at a rate of 25 mg/day for sixteen days. Combining both drugs in a single reservoir did not affect their respective release rates. When implanted subcutaneously in rats, HA reservoirs loaded with one dapsone tablet appeared to be well tolerated. After nine weeks, 77 mg of dapsone had been released. These experiments showed that HA reservoirs can be used to deliver dapsone and cimetidine in vivo.

Animals↗
PubMed1995

Effects of moderate chronic alcoholism treatment on fertilization.

The effect of 10% m/v ethanol treatment during 4 weeks on mice reproductive function was studied. Fertilization rates significantly decreased when oocytes came from alcoholic females. Oocytes viability were decreased since fragmented ova were increased. Also decreased number of oocytes per oviduct was found. Spontaneous activation was increased in alcoholic females. Motility and hyperactivation were not been altered by treatment. These results show that the female gamete seem to be more sensible to moderate chronic alcoholism than the male gamete.

Alcoholism↗
PubMedDate not supplied

Deleterious effects of chronic moderate alcohol intake by female mice on preimplantation embryo growth in vitro.

The susceptibility of preimplantation stages of embryo development to preconceptional alcohol ingestion by females has had little investigation. We have recently shown that chronic 10% (w/v) ethanol intake by young female mice reduces the ovulatory response and impairs the quality of the oocytes. The aim of this study was to investigate the effects of 10% ethanol administration for 30 days on immature female mice on the day of in-vitro fertilization (day 1) and on preimplantation embryo development. Female mice were ovulated on days 27 and 29 of ethanol treatment and in-vitro fertilization was performed 16 h post-human chorionic gonadotrophin administration (day 30). The oocytes from the ethanol-treated females inseminated with spermatozoa from control males, showed a significantly higher percentage of parthenogenetic activation compared to the control females. An increased percentage of fragmented oocytes was found after insemination, compared to control females. When the embryos were cultured, the percentage of 2-cell (day 2), 4-cell (day 3) embryos, and compacted morulae (day 4) was significantly reduced in treated females, compared to control females. On day 5, we found a highly significant decreased percentage of early and expanded blastocysts in the ethanol-treated females. The percentage of hatching and hatched (extruded) blastocysts was also reduced significantly in treated females at days 6 and 7 (blastocyst stages). An increased percentage of morphologically abnormal embryos was found on days 5 and 6 in ethanol-treated females compared with controls. We conclude that chronic moderate ethanol ingestion by young female mice results in decreased fertilization, embryo growth retardation, cleavage arrest, and abnormal embryo development in vitro.

Animals↗
PubMedDate not supplied

Alterations in preimplantation in vivo development after preconceptional chronic moderate alcohol consumption in female mice.

Although many studies have explored the effects of acute or chronic ethanol exposure during the postimplantation period on embryo/fetal development, few reports have described the ethanol effects on preimplantation embryo development. Little is known about the effects of ethanol consumption prior to gestation on embryo growth. Recently, we have shown that chronic moderate ethanol intake by prepubertal female mice reduces the ovulatory response and impairs in vitro fertilization and in vitro embryo preimplantation development. The purpose of the present work was to evaluate the effects of preconceptional chronic moderate ethanol ingestion on preimplantation embryo morphology and differentiation, the timing of cleavage and embryo growth in vivo, and to determine the time pattern in which alterations appear. Prepubertal female mice were treated with 10% (w/v) ethanol for 30 days prior to conception. After inducing ovulation on day 27 and 29 of the ethanol treatment, females were mated with control males and the day of presence of vaginal plug was day 1. On day 1, a decreased percentage of normal fertilized oocytes, elevated parthenogenetic oocyte activation and unfertilized eggs with abnormal metaphase II were found in ethanol-treated, compared to control females. On day 2, while any differences in the total percentage of 2-cell embryos were observed, the treated females had a significantly higher percentage of morphologically abnormal embryos, compared to control females. On day 3, the preconceptional consumption of ethanol produced significantly reduced percentages of compacted morulae and an increased percentage of uncompacted morulae. The total percentage of morulae in the treated females was lower than in controls. On day 4, ethanol-treated females showed significantly decreased percentages of hatched attached blastocysts and increased early blastocyst and morula percentages, compared to controls. Thus, preconceptional chronic moderate ethanol ingestion by prepubertal female mice produced retarded development, impaired blastocyst hatching, abnormal embryo morphology and embryo loss by fragmentation due to alterations induced in the female gamete.

Alcohol Drinking↗
PubMedDate not supplied

Impaired mouse fertilization by low chronic alcohol treatment.

Little is known about the effects of low chronic alcohol intake on fertility, particularly in females. Recently, we have shown that chronic 10% (w/v) ethanol treatment affects in-vitro fertilization of mouse female gamete. The aim of this study was to solve questions concerning the lowest dose and duration of ethanol treatment required to alter the fertility of immature and adult female and adult male mouse. Mice were treated with 5% and 2.5% (w/v) ethanol in drinking water for 4 weeks. The in-vitro fertilization rates were significantly decreased with the 5% ethanol when oocytes from prepubertal and pubertal ethanol-treated females were inseminated with spermatozoa from adult control males. The in-vitro fertilization rates were not diminished when oocytes from control females were inseminated with spermatozoa from adult ethanol-treated males. Haploid oocytes were increased when oocytes came from immature females treated with ethanol. The in-vitro fertilization rates were not decreased in adult treated females. The in-vivo fertilization rates were not modified when prepubertal ethanol-treated females were mated with adult control males. Fragmented oocytes, in the in-vitro fertilization experiments, were significantly increased when they came from prepubertal and adult treated females inseminated with ethanol-treated males. These results show that there is a threshold of the ethanol dose to produce an effect. Chronic low ethanol ingestion by immature female mice has a deleterious effect on their in-vitro fertilization. Furthermore, acute ethanol ingestion by adult females during the induction of ovulation resulted in high parthenogenetic activation and fragmentation of mouse oocytes.

Alcohol Drinking↗