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Biomedical subjects

M Prati

Publications and source records attributed to M Prati.

At least 37 records · Page 2Linked to original sources
PubMed1993

Alternatives to in vivo tests for teratologic screening.

During the last decade there has been a tremendous increase in publications describing methods for in vitro toxicological research and emphasizing their advantages, suitability and necessity, rather than the classical in vivo studies. In this review we shall look at and consider only a few short term tests, chosen on the basis of the particular relevance that they have in the evaluation of the substances: rodent whole embryo culture (for both pre- and post-implantation embryos), non-mammalian vertebrate embryo and invertebrate embryo cultures, organ culture, and at last cell culture. We have seen however that sometimes some of the developed methods suit neither the necessity of saving time, money, and animals, nor the consistency of the results in xenobiotic screening. The concomitant application of both in vivo and in vitro methodologies will improve the quality of teratological research, and therefore will contribute to a critical evaluation of developmental hazards.

Abnormalities, Drug-Induced↗
PubMed1992

Effects of ethanol and acetaldehyde on rat embryos developing in vitro.

Rat embryos were explanted on Days 9.5 or 10 of gestation and cultured for 48 to 30h, respectively, in rat serum containing 0, 3, 6, 9 mg/ml of Ethanol (Eth); 0, 10, 20 micrograms/ml of Acetaldehyde (Ach); 3 mg/ml Eth + 10 micrograms/ml Ach. At the end of the culture period the embryos were evaluated for vitality, and scored. Some of them were also examined histologically. Embryos exposed to Eth from Day 9.5 showed a dose-related growth retardation associated with a high frequency of malformations (open neural tube, heart defects, branchial arch hypoplasia). The exposure of 9.5-day embryos to 20 micrograms/ml Ach resulted in 100% embryolethality, whereas 10 micrograms/ml induced growth retardation and teratogenic effects. When 10-day embryos were exposed to 3 mg/ml Eth or 10 microliters/ml Ach no effects were observed, but the highest levels of Eth produced a moderate growth retardation and morphologic defects. Exposure to 20 micrograms/ml Ach induced hypoplasia of the first arch, but did not alter the score value. The histologic examination of these embryos revealed severe lesions at the level of the neuroepithelium and of the branchial mesenchyma. Similar effects were observed in embryos exposed simultaneously to 3 mg/ml Eth and 10 micrograms/ml Ach. These results should make us reevaluate the role of Ach in the Eth-induced embryopathies.

Abnormalities, Drug-Induced↗
PubMed1992

HPLC analysis of free amino acids and amino acids of total proteins in cultured cells: an application to the study of rat Sertoli cell protein metabolism.

A simple, rapid and, sensitive HPLC method, coupled with fluorometric detection, has been worked out and employed to determine the intracellular free amino acid concentrations and the amino acid composition of total proteins in rat Sertoli cell primary culture. Sertoli cells were isolated enzymatically from testes of 20- and 28-day-old rats and cultured at 32 degrees C in Eagle's minimum essential medium. On the second day of culture, cell monolayers were quickly rinsed with ice-cold saline, immediately frozen in liquid nitrogen, accurately harvested, and homogenized in 10% trichloroacetic acid. Tissue free amino acids were determined in the acidic soluble fraction following neutralization, while the precipitate was hydrolyzed for the evaluation of the fractional content of amino acids into total proteins. Amino acid samples were derivatized with o-phthaldialdehyde/3-mercaptopropionic acid and resolved by a linear one-step acetonitrile gradient in 12.5 mM sodium phosphate buffer, pH 7.2, employing a 5-microns particle size reversed-phase column. Fluorescence was monitored with excitation at 330 nm and emission at 450 nm. Under these conditions all major physiological amino acids could be satisfactory separated, identified, and subsequently quantified with the aid of standards. The run time was about 50 min; the linearity was excellent over a large range of concentrations (1-800 pmol) and the lower limit of sensitivity appeared to be 0.5 pmol. This method permits us to demonstrate age-dependent modifications in the intracellular amino acid pool and to adequately evaluate the process of protein synthesis in cultured Sertoli cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1992

L-thyroxine and 3,5,3'-triiodothyronine concentrations in the chicken egg and in the embryo before and after the onset of thyroid function.

The concentrations of T4 and T3 were measured by specific RIAs in chicken embryonated eggs and embryonic tissues before (at 4 and 6 days of incubation) and after the onset of thyroid function (at 10-20 days). All samples were submitted to extensive delipidation and purification. T4 and T3 were found in the yolk, as described by others, and also in the egg white, although at lower concentrations. The initial total maternal supplies per egg are 67 ng T4 and 30 ng T3 in the yolk, and 2.4 ng T4 and 1.9 ng T3 in the egg albumen. Whole 4-day-old embryos contained a total of 2.48 pg T4 and 0.65 pg T3. The head (mostly brain) of 6-day old embryos contained 4.1 pg T4 and 4.6 pg T3; T4 (but not T3) was also measurable in the carcass. The concentrations of T4 increased progressively between 10 and 20 days in the brain, eyes, liver, and heart; they were especially high in the eyes (4.8 ng/g) and liver (8.2 ng/g) at 20 days. T3 levels increased markedly in the brain (to 5.1 ng/g at 20 days) and less markedly in the eyes (to 1.3 ng/g) and heart (to 1.6 ng/g), but were low and stable in liver up to 18 days (0.3 ng/g), after which there was a sudden increase to 1.4 ng/g at 20 days. Iodothyronines are, therefore, available to the chick embryo throughout development both before and after the onset of thyroid function. T3 concentrations, especially in the brain, reach much higher levels than previously inferred from the low plasma T3 levels. These findings show similarities with those described for the fetal rat.

Analysis of Variance↗
PubMed1992

[Effect of insulin-like growth factor I (IGF-I) on Sertoli cell metabolism in the pubescent rat].

The influence of Insulin-like Growth Factor I (IGF-I) on some metabolic functions of Sertoli cells from peripubertal rats was investigated. Sertoli cells were isolated from the testes of 24-day-old animals and cultured at 32 degrees C in Eagle's MEM with or without 1 nM IGF-I. Sertoli cells cultured in the presence of IGF-I showed increased nuclear RNA polymerase activity (+80%) and augmented protein synthesis (+50%).

Animals↗
PubMed1991

Diet composition modifies embryotoxic effects induced by experimental diabetes in rats.

Despite improvements in prenatal care, the incidence of congenital malformations in diabetic pregnancies is still 3-4 times higher than in normal pregnancies. These defects could be attributed to alterations of intrauterine environment due to disorder of the maternal metabolism. If this were true, the quality of food could play a role in diabetes-induced embryotoxicity. To check this hypothesis, female CD rats were made diabetic by injecting intravenously 50 mg/kg of streptozotocin 2 weeks before mating. From the first day of pregnancy they were divided into three groups and maintained on the following diets: (1) standard diet (Italiana Mangimi); (2) purified high protein diet (protein 55%, carbohydrates 25.5%, fat 7.5%, fiber 4.5%, ash 7.5%); (3) purified normoprotein diet (protein 19%, carbohydrates 62.5%, fat 7.5%, fiber 4%, ash 7%). Nondiabetic pregnant females fed with standard diet served as negative control. No significant differences were observed in blood glucose levels among the groups (range 410-500 mg/dl). The group fed on normoprotein diet showed at term of pregnancy: (1) higher rate of resorptions; (2) lower fetal weight; (3) higher frequency of major malformations than the groups fed standard and hyperproteic diets. Although we are not able at this time to discriminate between a protective effect of a diet with a high protein content and a disruptive effect of a diet containing high quantity of carbohydrates, the results of this trial support the hypothesis of a fuel-mediated teratogenesis in diabetic pregnancy.

Animals↗
PubMed1991

[Nuclear triiodothyronine receptors in the testis of the growing rat are regulated by the thyroid status].

The effects of thyroid status on the binding capacity, association constant (Ka) and receptor occupancy during postnatal rat testis development were evaluated. Hypothyroidism (induced by oral administration of 0.05% methimazole from the day of birth) increased the total T3 binding capacity in the testis, retarding the normal developmental decrease in T3 receptor number (mean maximal binding capacities estimated by Scatchard analysis for 21-day-old eu- and hypothyroid rats were 117 and 173 fmol/mg DNA, respectively). The rat thyroid status also affected the percentage of T3 receptor occupancy but not the affinity of binding (as measured by Ka). The postnatal developmental changes in T3 binding capacity induced by hypothyroidism were completely reversed by T3 replacement. These results suggest that T3 nuclear receptors in the developing rat testis are modulated by thyroid hormones.

Animals↗
PubMed1990

Thyroid hormone stimulates the production of insulin-like growth factor I (IGF-I) by immature rat Sertoli cells.

The effects of thyroid hormone on insulin-like growth factor I (IGF-I) production by Sertoli cells isolated from immature rats have been investigated. In Sertoli cells from hypothyroid rats the production of IGF-I was significantly lower than in controls and was greatly stimulated by the administration of triiodothyronine (T3) in vivo. The in vitro addition of physiological doses of T3 (1 nmol/l) significantly increased the production of IGF-I by cultured Sertoli cells indicating a direct action of the hormone on local IGF-I production. Our results suggest the involvement of IGF-I in the thyroid hormone-dependent maturation of testicular function.

Animals↗
PubMed1990

Induction of micronuclei and toxic effects in embryos of pregnant rats treated before implantation with anticancer drugs: cyclophosphamide, cis-platinum, adriamycin.

To evaluate a possible relationship of maternal exposure to anticancer drugs during the preimplantation period to blastopathies and postimplantation embryotoxicity, CD female rats were injected intraperitoneally on day 3 of pregnancy with 15 and 30 mg/kg of cyclophosphamide (CPA), 2 and 4 mg/kg of Adriamycin (ADR), 3 and 6 mg/kg of cis-platinum (Cis-Pt), or with 5 ml/kg of saline. Blastocysts were collected on day 5 of gestation and evaluated for gross morphology, cell number, and micronuclei. Some females were sacrificed on day 21 of pregnancy in order to evaluate postimplantation embryotoxicity. A reduction in cell number/blastocyst was observed only in animals exposed to Cis-Pt 6 mg/kg; vice versa, a dose-related increase of micronuclei and of blastocysts with micronuclei was found in all groups treated with the anticancer agents. A significant increase of postimplantation loss was recorded in the groups treated with high doses of Cis-Pt and ADR, but no clear signs of teratogenicity were observed.

Animals↗
PubMed1990

Influence of hypothyroidism on in-vitro testicular steroidogenesis in adult rats.

The influence of hypothyroidism on testicular steroidogenesis was investigated by evaluating the production of testosterone and its precursors by isolated testes from adult male rats. Animals were made hypothyroid starting from the 4th week of life either by daily oral administration of 0.1% methimazole (MMI) or by surgical thyroidectomy (TZ). Half of the thyroidectomized rats were i.p. injected with 3 gamma T3/100 g body weight on alternate days during the last three weeks before sacrifice. Hypothyroidism is associated with a severe retardation of body growth, which appears more marked in thyroidectomized than in MMI treated rats; no significant variations in testis weight are observed. Administration of T3 does not completely restore body weight. A significant decrease in the "in vitro" production of testosterone and its precursors by testes isolated from hypothyroid rats is observed. This effect is more evident in thyroidectomized rats where a marked drop in the "in vitro" production of some testosterone delta 4 precursors is associated with the increase in DHEA/delta 4 ratio. T3 injection to thyroidectomized rats only partially restores the "in vitro" testosterone production. Results suggest that as the degree of hypothyroidism became more severe, the rate of testosterone production decreases and testicular steroidogenesis changes from the delta 4 to delta 5 metabolic pathway as a consequence of the impairement of 3-beta-ol-dehydrogenase activity.

Androstenedione↗
PubMed1990

The effect of L-acetylcarnitine on some reproductive functions in the oligoasthenospermic rat.

The effect of L-acetylcarnitine (LAC) on some parameters of male reproductive function was studied on rats made oligoasthenospermic with dibromochloropropane (DBCP). DBCP depresses sperm count and motility. After one injection of the drug, LAC induces a recovery of both sperm count and motility but after two injections it is ineffective. This effect is also shown visually by microscopic examination of seminiferous tubules. Among the enzymatic activities evaluated as biochemical markers of testicular function both lactate dehydrogenase and NADPH-cytochrome P 450-reductase increased significantly (P less than 0.05) after treatment with LAC in normal rats. LAC also stimulates testosterone production. It is suggested that LAC may affect testicular function.

Acetylcarnitine↗
PubMed1990

Morphogenesis of diabetes-induced congenital cataract in the rat.

The eye development of rat fetuses and pups from normal and streptozotocin-diabetic mothers was studied histologically in order to verify the morphopathogenesis of congenital cataract. The first signs of lens alterations were observed in 17-day-old fetuses from diabetic mothers. The fibres swelled up, became hydropic and subsequently degenerated, giving rise to large cysts filled with amorphous material in the middle of the lens. The pathogenic route observed suggests an osmotic disturbance in the physiology of the lens fibres, probably related with an accumulation of some polyols.

Animals↗
PubMed1990

Congenital malformations in offspring of diabetic rats: experimental study on the influence of the diet composition and magnesium intake.

In spite of improvements in the treatment of diabetes, the risk of congenital malformations in diabetic pregnancy is three to four times higher than in normal pregnancy. This might be due to the metabolic abnormalities of diabetic pregnancy that also affect mineral metabolism. Since diabetes can lower both maternal and fetal blood Mg levels, and Mg deficiency has been shown to be teratogenic in laboratory animals, we decided to investigate which effects Mg deficiency would have in inducing embryopathy in diabetic animals. Female CD rats were divided into six groups. Groups 1 and 2 were fed a standard diet (Mg content 4,200 ppm), groups 3-6 a purified diet (Mg contents 4,200, 500, 250, or 125 ppm). Groups 2-6 had been made diabetic by an intravenous injection of 50 mg/kg streptozocin 1 week before mating. The rats were killed on day 21 of pregnancy, and the live fetuses were examined for external, skeletal, and visceral malformations. The maternal and fetal blood glucose levels were the same in all diabetic groups. The maternal Mg levels in groups 2 and 3 were the same as in controls, but definitely lower in groups 4-6. Embryotoxicity (embryonic deaths, delayed development, congenital malformations) was higher in the groups fed the purified diet than in group 2, but without a clear relation to the dietary Mg levels. We cannot draw any conclusions about the effects of Mg deficiency in diabetic pregnancy from our results, but they show that the quality of the diet is of major importance in the manifestation of embryotoxicity in diabetes.

Animals↗
PubMed1986

Effects of streptozotocin-induced diabetes on fetal development of the rat.

The purpose of this study was to determine whether or not in rats with experimentally induced diabetes there is an increased frequency of congenital malformations; data in the literature are not consistent on this point. Virgin CD females rats were injected with 40-50 mg/kg streptozotocin (Stz) before mating (SIBM group) or on the first day of pregnancy (SI1). Both SIBM and SI1 females were divided into two groups according to their blood glucose levels: severely diabetic (SD, greater than 300 mg%) and mildly diabetic (MD, 120-250 mg%). Food and water consumption by the control and MD groups were the same, but the SD females developed polyphagia, polyuria, and polydypsia, which continued to increase throughout pregnancy, as did the blood glucose levels. All the MD females mated and carried to term. In SD females both frequency of mating and fertility were only slightly lower than in the controls. All the females were killed on the 21st day of pregnancy. Pre- and postimplantation losses were the same for diabetic and control rats, but SIBM-SD females ovulated less than other groups. Weights of fetuses of SD dams were lower and blood sugar levels higher than those of the other groups. The placentas of SD rats were significantly heavier and there was cystic degeneration of spongiosa. The incidence of major malformations was minimal (approximately 2%) in fetuses of SD females and there were none at all in controls or MD females. In conclusion, our data are in agreement with those of other investigators who have found that rats with experimentally induced diabetes have smaller fetuses and increased placental weight.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Embryotoxic effects of 2,3,7,8 tetrachlorodibenzo-p-dioxin administered to female rats before mating.

2,3,7,8-Tetrachlorodibenzo-p-dioxin was administered to female rats by gavage for 2 consecutive weeks at daily doses of 0, 0.125, 0.5, and 2 micrograms/kg. After treatment females were caged with untreated males. All dams were killed on Day 21 of gestation. Their reproductive statuses were recorded and live fetuses were examined for external, visceral, and skeletal malformations. At 0.125 micrograms/kg no effects were observed on both maternal and fetal toxicity; 0.5 micrograms/kg reduced maternal weight gain and increased postimplantation loss. At 2 micrograms/kg the following features became evident: reduction of both maternal weight gain and ovulation rate, increase of pre- and postimplantation loss, and fetal growth retardation. Also, malformed fetuses were observed at this dose level.

Abnormalities, Drug-Induced↗