Biomedical subjects

M Prati

Publications and source records attributed to M Prati.

At least 19 recordsLinked to original sources

PubMed2002

Biological effect of the Planktothrix sp. FP1 cyanobacterial extract.

Cyanobacteria are common and potentially harmful inhabitants of freshwater and marine environments worldwide. Some waterbloom-forming cyanobacteria are toxic and they may cause animal death and adversely affect human health. A filamentous freshwater cyanobacterium, Planktothrix sp. FP1, was found to be responsible for a toxic algal bloom in Lake Varese (Italy) during August of 1997. In the present study, the biological effects of the Planktothrix sp. FP1 cell extract on Xenopus embryos and on human Peripheral Blood Mononuclear Cells (PBMC) were investigated. FETAX (Frog Embryo Teratogenesis Assay-Xenopus) showed that the cyanobacterial extract had no teratogenic potential, though embryotoxicity was detected (LC(50) 2.944g/l wet weight). The same extract inhibited the proliferation of PBMC stimulated in vitro by phytohemagglutinin (PHA), and strongly interfered with the production of interleukin-2 (IL-2) and interferon-gamma (IFN-gamma).

Animals↗

PubMed2002

[Intestinal carcinoma in Crohn's disease. Report of four cases and review of the literature].

BACKGROUND: Increasing numbers of intestinal carcinomas in patients affected by Crohn's disease have been reported by several authors, even if the strength of this associations (age, longstanding of the disease, its characteristics and distribution) still has to be elucidated. METHODS: From January 1992 to July 2000, 130 patients with Crohn's disease were submitted to surgery. RESULTS: Four patients showed an associated intestinal carcinoma at operation, in 3 cases located in the ileum, and in 1 case in the colon. Patients' mean age was 54 years. Mean duration time of the Crohn's disease was 7 years. One patient died 3 months after surgery for disseminated peritoneal carcinomatosis, whereas 3 patients are still alive with malignancy free at 5, 8, and 11 years after the tumor resection. CONCLUSIONS: These results suggest the difficulty in recognizing patients with Crohn's disease who are at risk for intestinal carcinoma. Longstanding disease, previous intestinal exclusion surgery, enterocutaneous or other types of fistulas should be considered for the development of cancer. Therefore, the prognosis may be good if early diagnosis and treatment are made.

Aged↗

PubMed2000

Ecotoxicological soil evaluation by FETAX.

The frog embryo teratogenesis assay-Xenopus (FETAX) is a powerful and flexible bioassay that makes use of the embryos of the anuran Xenopus laevis. FETAX satisfies the requirements of low cost, reliability and reproducibility and, thanks to its three endpoints (i.e., mortality, teratogenicity and growth inhibition) can detect the xenobiotics that affect embryonic development. In this paper, we have used FETAX to evaluate samples of soils collected in an oil-contaminated area. Embryos were exposed directly to the soil to be tested. Particular attention was devoted to provide a statistical procedure for analysing mortality and malformation data as well as growth retardation.

Accidents↗

PubMed2000

In vitro teratogenic potential of two antifungal triazoles: triadimefon and triadimenol.

The teratogenic potential of two antifungal triazoles (Triadimefon and Triadimenol) has been investigated in vitro by the rat postimplantation whole embryo culture method. Rat embryos 9.5 d old were cultured for 48 h in rat serum with Triadimefon (12.5-250 microM) or Triadimenol (6.25-125 microM) and then examined. Some embryos exposed to Triadimenol (6.25-125 microM) were cultured for 12 extra hours in control serum to improve their developmental degree and then immunostain cranial nerves and ganglia. The exposure to the highest doses of triazoles only moderately reduced some morphometrical developmental parameters. By contrast, 25-250 microM Triadimefon and 25-125 microM Triadimenol induced specific concentration-related teratogenic effects at the level of first and second branchial arches. After immunostaining, embryos exposed to 12.5-125 microM Triadimenol showed specific cranial nerve and ganglia abnormalities. The possible implication of neural crest cell alterations on triazole-related abnormalities is discussed.

Abnormalities, Drug-Induced↗

PubMed1999

Morphological alterations induced by sodium valproate on somites and spinal nerves in rat embryos.

The antiepileptic drug valproic acid is a well-known teratogenic agent; its main target organ is the neural tube, though skeletal malformations have also been described. In our recent work, respecifications of vertebrae were described in rat fetuses after treatment with 400 mg/kg of sodium valproate at specific somitogenic stages. The observed malformations were stage-dependent. Morphological segmental respecification was observed at the level of segments in formation at the moment of exposure and at the level of more posterior segments. Recently, specific alterations in the development of cranial nerves and ganglia were described in mouse embryos after in vitro exposure to VPA. The aim of the present work was to analyze dysmorphogenetic effects of VPA on embryonic metameric structures: somites, spinal and cranial nerves, and ganglia. Sodium valproate (400 mg/kg) was subcutaneously injected at specific gestational times corresponding to embryonic stages: presomitic or at about 2, 6, 10, 14, 18, or 22 somites. Females were sacrificed on the day 12 post coitum, and embryos were examined. Morphological examination of somites was performed by staining with acridine orange. Morphological examination of nerves and ganglia was performed by immunostaining, using monoclonal antibodies to the 160-kD neurofilament protein. No abnormalities were observed in the cranial nerves and ganglia. Specific and stage-dependent alterations were observed both at the level of the somites and at the level of the spinal nerves. The following characteristic malformations were observed: fusions, duplications, and reductions of somites and corresponding spinal nerves and ganglia. Our morphological data suggest a morphogenetic action of VPA at the level of the axial segments, with a possible respecification of the identity of the interested segments and their derivatives.

Animals↗

PubMed1999

Development of rat embryos cultured in serum from diabetic rats.

Experimental studies carried out in vitro suggest a role of oxidative stress in diabetes-induced embryopathies. Glutathione is the main defense against free radicals in embryonic as it is in adult tissues. In this experiment, using postimplantation whole-embryo culture, we analyze: (1) the effects of serum from streptozotocin-induced diabetic rats on embryonic development and on glutathione distribution between the yolk sac and embryonic tissues and (2) the role of glutathione in preventing embryopathies (using the inhibitor of glutathione synthesis buthionine sulfoximine). Our data show that in rat embryos cultured in diabetic serum, the only observed effects are at the yolk sac level. No effects on the glutathione content were observed. The addition of buthionine sulfoximine reduced the glutathione content and produced signs of developmental delay in embryos cultured in diabetic serum, suggesting a role of the oxidative stress in producing diabetes-related embryotoxicity.

Animals↗

PubMed1998

Stage-dependent skeletal malformations induced by valproic acid in rat.

In this work we study the skeletal teratogenic response in rats exposed to NaVP at different embryonic stages. Crl:CD female rats were treated subcutaneously with 400 mg/Kg b.w. NaVP at presomitic stage (group II) or nearly at 2, 6, 10, 14, 18 or 22 somites (groups III-VIII). The females on group I were treated with saline and served as controls. No treatment-related effects were observed at the level of resorptions, live fetuses and fetal or placental weight. The skeletal examination showed characteristic patterns of malformations strictly related to the period of treatment. In particular, groups II and III showed a significant increase of alterations of cervical vertebrae (mainly 1st to 3rd segment) and a decrease of the frequency of extra lumbar ribs in comparison to control. Group IV showed severe abnormalities localized at the 4th to 7th cervical segment and at the level of the 1st and 2nd thoracic segments, including duplications of thoracic segments 1, 2 or 3. The fetuses of group V were characterized by several alterations of the thoracic segments distributed without a clear specificity. In group VI, the thoracic region was also affected with some specificity at the level of the segments 4th to 9th; in group VII, last thoracic and lumbar segments were affected (mainly duplications) and in group VIII only lumbo-sacral abnormalities were recorded. These results confirm the specific effect of NaVP at the level of the axial skeleton and suggest a possible interaction with the expression of genes identifying the vertebral segments.

Alcian Blue↗

PubMed1996

Teratogenic effects of sodium valproate in mice and rats at midgestation and at term.

This experiment was carried out with the aims of comparing the embryotoxic potential of valproic acid (VPA) in rats and mice, better defining the malformation pattern in these species, and comparing the embryotoxic effects detectable in mid-pregnancy to those observed in fetuses at term. Pregnant CD:Crl rats were treated subcutaneously (s.c.) at 08:00, 16:00, and 00:00 on day 9 of gestation with 0, 150, or 300 mg/ kg VPA; pregnant NMRI mice were treated s.c. at 00:00 on day 7 of gestation, and at 08:00 and 16:00 on day 8 of gestation with 0,75, 150, or 300 mg/kg VPA. Groups of females were killed on day 9 (mice) or day 11 (rats) of pregnancy and their embryos were carefully examined under a dissecting microscope. The remaining females were killed 1 day before parturition and their fetuses were examined for external, visceral, and skeletal malformations. A very high frequency (84%) of malformed embryos was recorded in the group of mice treated with 300 mg/kg, including open brain folds (73%), somite defects (36%), and heart malformations (20%). The rat embryos were less sensitive: only 43% of them were malformed after treatment with 300 mg/ kg, however, the pattern of malformations was quite similar to that observed in mice. The treatment with 150 mg/kg produced about 32% malformed embryos in mice and only 8.5% in rats. More than 84% of mouse fetuses from mothers treated with the highest dose showed a severe form of exencephaly. The axial skeleton was also severely affected. The postimplantation loss reached 52%. Exencephaly and skeletal malformations were also recorded in mouse fetuses from mothers exposed to 150 mg/kg. The dose of 75 mg/kg was without effects. Exencephaly was not observed in rat fetuses at term. In this species the axial skeleton was the most severely affected region at 300 mg/kg, while the lowest dose produced only sporadic malformations. These results confirm that the mouse is the more sensitive species for the teratogenic effects of VPA. Furthermore, it has been shown that, in both species, the axial skeleton is a system which is very sensitive to the teratogenic effects of VPA. The observed alterations show a possible link between axial specification and VPA and suggest further studies of embryos exposed to VPA for the expression of genes controlling the identity of vertebral segments.

Abnormalities, Drug-Induced↗

PubMed1996

Glutathione status in diabetes-induced embryopathies.

The mechanism involved in diabetes-induced embryotoxicity is still unclear. Mitochondrial alterations probably produced by oxidative stress have been described in embryos developing in a diabetic environment. Furthermore, oxygen radicals-scavenging enzymes can reduce the embryotoxic effects induced by diabetic conditions. In this work we tried to test if glutathione (GSH), a tripeptide implicated in cellular protection against reactive oxygen species, is involved in diabetes-related embryotoxicity. Rat embryos were explanted on day 11 on gestation from normal and from streptozotocin-diabetic mothers. The embryos were examined morphologically, then protein, DNA and GSH were determined both in embryos and in their visceral yolk sacs. The embryos explanted from diabetic mothers showed signs of developmental retardation and 16% were morphologically abnormal. GSH content was reduced in these embryos in comparison to control, but the GSH/protein in the visceral yolk sacs of conceptuses explanted from diabetic mothers was higher than in control visceral yolk sacs. Our hypothesis is that the reduction of embryonic GSH is a consequence of the alteration in GSH transport across the yolk sac endodermal cells damaged by diabetic conditions. The observed reduction in embryonic GSH could reduce the protection against the oxidative stress condition described in diabetic pathology.

Animals↗

PubMed1996

Differential and tissue-specific regulation of (pro)insulin and insulin-like growth factor-I mRNAs and levels of thyroid hormones in growth-retarded embryos.

The control of embryonic growth in vertebrates appears to rely on the orchestrated action of several families of growth factors and hormones. The contribution of insulin-like growth factor (IGF-I) to prenatal growth regulation is better established in mammals than in other vertebrate species. The status of (pro)insulin gene product(s) in the pancreas and non-pancreatic tissues may be another important contribution to embryonic growth signals. We have characterized tissue sources of IGF-I gene and (pro)insulin gene mRNAs in normal chicken embryogenesis and their changes in a model of avian growth retardation. We studied, by a highly sensitive reverse-transcription coupled to polymerase chain reaction (RT-PCR), the expression of IGF-I and (pro)insulin genes in brain, pancreas, liver and eye in embryos from late organogenesis (E8) to late development (E17); hatching is at E20-21, a period of fast embryonic growth. In brain, pancreas and eye, growth-retarded embryos had lower IGF-I mRNA expression. In contrast, in the liver, little IGF-I mRNA was found during normal embryogenesis, but some early induction occurred in E17 growth-retarded embryos. (pro)insulin gene expression was much lower in absolute levels in non-pancreatic tissues than in pancreas. However, it was developmentally regulated in brain, liver and eye. The growth-retarded, IGF-I-deficient embryos had an increased expression of (pro)insulin mRNA in the brain. While IGF-I treatment of growth-retarded embryos increased their serum IGF-I values, only partial recovery of embryonic weight was obtained. Since abnormalities in other hormones may contribute to the failure of systemic IGF-I to reverse the retarded phenotype, thyroid hormones (T3 and T4) levels were determined in liver, brain and eye. They were markedly altered only in the liver of growth-retarded embryos, where an increase in thyroid hormone content was observed. We conclude that, in chicken embryos and possibly other vertebrates, normal growth may implicate multiple hormones, including the concerted action, endocrine/paracrine, of IGF-I and (pro)insulin gene products.

Animals↗

PubMed1995

In vitro development of rat embryos obtained from diabetic mothers.

Rat embryos of 9.5 or 10 days of gestation were removed from control or streptozotocin-diabetic mothers and cultured in normal rat serum (180 mg% glucose) or in diabetic serum (600 mg% glucose). The development of control embryos in normal serum was adequate. Embryos from normal mothers cultured in diabetic serum showed signs of developmental retardation. The development of embryos obtained from diabetic mothers was severely impaired, regardless of the gestational age or the culture medium. These results suggest that a diabetic maternal milieu produces irreversible effects in the embryo very early in gestation.

Animals↗

PubMed1995

Follow-up study on the effects of thyroid hormone administration on androgen metabolism of peripubertal rat Sertoli cells.

The inhibitory effect of triiodothyronine (T3) given in early postnatal life on Sertoli cell proliferative activity, leading to their precocious terminal differentiation, has been demonstrated previously. However, data concerning the role of thyroid hormone on androgen metabolism of Sertoli cells during the same period are still lacking. In this study we performed a time-course investigation on the effects of T3 treatment on testosterone metabolism in Sertoli cells isolated from 2-, 3- and 4-weeks-old euthyroid rats. Triiodothyronine (3 micrograms/100 g body wt) was given ip., during the last week prior to sacrifice. Sertoli cells from all animal groups initially were cultured under basal conditions during the first 24 h and subsequently in the presence of testosterone (0.5 mumol/l) with or without T3 (1 nmol/l) for an additional 24 h. This treatment given to 2-week-old animals resulted in reduced testicular growth. As far as androgen metabolism is concerned, T3 in vivo and in vitro treatment in 2- and 3-week-old animals induced a lowering of dihydrotestosterone + 3 alpha-diol with an enhancement of the two other 5 alpha-reduced androgens. The effect was much less pronounced in the oldest group. In both 2- and 3-week-old treated rats a marked reduction of oestradiol was observed, which indicates an inhibition of aromatase activity, mainly in younger animals. This enzyme has been reported to be extremely active in Sertoli cells of rats (of the same strain) between the age of 5 and 20 days, but it decreases rapidly thereafter.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗

PubMed1995

Tri-iodothyronine directly affects rat Sertoli cell proliferation and differentiation.

The addition of physiological concentrations (1 nM) of tri-iodothyronine (T3) to the culture medium of Sertoli cells from prepubertal (8-day-old) rats stimulated both protein synthesis (+55%) and lactate (+50%) production, while it inhibited DNA synthesis (-30/35%) and aromatase activity (-45/50%); insignificant T3-dependent effects were observed in cultured Sertoli cells from midpubertal (28-day-old) rats. These data suggest an age-dependent role for thyroid hormone in promoting and maintaining Sertoli cell differentiation at puberty; more-over, the hormone is involved in the regulation of Sertoli cell proliferation. The present study validates the role of Sertoli cells as a specific target for T3 action at the testis level; it also demonstrates the existence of an early and critical direct influence of thyroid hormone on Sertoli cell proliferation and functional maturation.

Animals↗

PubMed1994

Effect of thyroid status on the oxidative capacity of Sertoli cells isolated from immature rat testis.

Our previous studies indicate the Sertoli cell as a target for thyroid hormone action at testis level. In the present study we evaluated the effect of thyroid hormone on Sertoli cell oxidative capacity measured by specific cytochrome oxidase (COX) activity and intracellular adenosine triphosphate (ATP) content. Sertoli cells were isolated from 21-day-old rats. Hypothyroidism, induced from the day of birth by administration of 0.025% methimazole, was characterized by a severe delay of body and testis growth and resulted in a lower COX activity (-40%, p < or = 0.01) and a lower ATP content (-35%, p < or = 0.01) by isolated Sertoli cells. Administration of triiodothyronine (10 micrograms/100 g body wt on alternate days) to hypothyroid rats improved body and testis growth and restored both COX activity and ATP content. The presence of high-affinity, low-capacity binding sites for triiodothyronine in Sertoli cell mitochondria also was demonstrated. This study, unlike that carried out on the whole testis from adult rats, demonstrates that thyroid hormone affects the energy metabolism of Sertoli cells from midpubertal rat testes.

Adenosine Triphosphate↗

PubMed1994

Influence of thyroid hormone on androgen metabolism in peripuberal rat Sertoli cells.

The aim of the present study was to investigate the influence of thyroid hormones on androgen metabolism in Sertoli cells isolated from 3- and 4- week-old rats. Hypothyroidism was induced by the oral administration of 0.025% methimazole (MMI) from birth until the rats were killed at 3 and 4 weeks of age. Half of the MMI-treated animals were injected i.p. with L-triiodothyronine (T3 3 micrograms/100 g body weight) during the last week before death. Sertoli cells from all groups were initially cultured under basal conditions for the first 24 h and subsequently in the presence of testosterone with or without T3 for an additional 24 h. Hypothyroidism was associated with severe impairment of body as well as testicular growth. Indeed, body and testicular weights were similar in 4-week-old hypothyroid animals to those in 3-week-old control rats. Testosterone metabolism in Sertoli cells isolated from 3- and 4-week-old hypothyroid rats was mainly expressed by the lowering of 5 alpha-dihydrotestosterone + androstane 3 alpha, 17 beta-diol and an enhanced formation of 5 alpha-reduced steroids with poor androgenic properties (e.g. 5 alpha-androstane, 3, 17 alpha-dione (androstanedione), 5 alpha-androstane, 3-ol-17-one (androsterone)). Treatment of the same group of animals with T3 in vivo and in vitro did not influence the pattern of 5 alpha-reductase steroids substantially. The most striking finding in the Sertoli cells of 3-week-old hypothyroid rats was the dramatic enhancement of oestradiol formation which persisted to a lesser extent 1 week later.(ABSTRACT TRUNCATED AT 250 WORDS)

Androgens↗

PubMed1993

The protective effects of N-acetyl-L-cysteine against methyl mercury embryotoxicity in mice.

N-Acetyl-L-cysteine (NAC) has been widely used in the protection against the toxic effects produced by several chemicals because of its radical scavenger properties and because NAC is a precursor of glutathione, one of the most important intracellular defenses against oxidants. The aim of this investigation was to verify the potential protective activity of NAC against the well-known embryotoxicity induced by methyl mercuric chloride (MMC) in mice. Three experimental approaches were carried out. In the first investigation, acute treatment of MMC (25 mg/kg po) was given in CD female mice on Day 10 of pregnancy, and was followed immediately and/or after 24, 48, and 72 hr by administrations of NAC (800 mg/kg i.v.). The embryolethal effects caused by MMC poisoning were completely antagonized by just a single administration of NAC, while the incidence of palatoschisis was reduced in relation to the number of NAC administrations. In the second experiment MMC was chronically gavaged (3 mg/kg/day po) during the period of organogenesis on Days 5 to 14 of gestation. During the same period of time some of these females were also exposed to 1% NAC dissolved in drinking water. MMC poisoning reduced the body weight of viable fetuses and induced many cases of palatoschisis. The body weight of fetuses from MMC-poisoned mothers treated with NAC was improved and the incidence of palatoschisis was in the normal range. In the last experiment the treatment with NAC (400 mg/kg i.v., during the period of organogenesis) drastically reduced the severe embryolethality induced by MMC (6 mg/kg/day po) administered during the same period of time.(ABSTRACT TRUNCATED AT 250 WORDS)

Abnormalities, Drug-Induced↗

PubMed1993

Effects of diets with different content in protein and fiber on embryotoxicity induced by experimental diabetes in rats.

Three groups of streptozotocin-diabetic rats were maintained during pregnancy on three hyperproteic diets with different protein contents. These differences were compensated by an equal quantity of fiber (group 1: protein 55.0%, fiber 4.5%; group 2: 45.0%, 14.0%; group 3: 35.0%, 24.0%). Three groups of nondiabetic pregnant rats were fed with the same diets and served as control. The differences of the daily protein intake among the diabetic groups were less pronounced than those expected on the basis of the diet composition, and the embryopathic effects (reduced fetal weight, increased in malformation and resorption rate) were not statistically different among the three groups of diabetic animals. The frequency of congenital malformations was higher than that observed in a previous experiment in diabetic rats maintained on a standard diet, but much lower than that observed in animals fed on a purified, fiber-poor, normoproteic diet. When the caloric intake of the diabetic rats in the different groups was determined it was found to be similar for all of them and also similar to the caloric intake of the rats given a standard nonteratogenic diet (in previous experiments), while the rats maintained on a normoproteic, teratogenic diet increased their caloric intake. These results seem to indicate that the diet composition greatly influences the intake of food and calories of pregnant diabetic rats and this may play a role in modulating the embryopathic effect of diabetes.

Analysis of Variance↗

PubMed1993

Thyroidal regulation of nuclear tri-iodothyronine receptors in the developing rat testis.

Previous work has demonstrated that thyroid hormones influence testis development. Specific receptors for tri-iodothyronine (T3) have been demonstrated in Sertoli cells. The aim of the present study was to examine the possible effect of thyroid hormone on its own receptor during pubertal development by evaluating the influence of thyroid status on T3-binding capacity, -binding affinity and receptor occupancy in nuclei isolated from immature rat testes. The binding capacity for T3 of nuclei from rat testis significantly decreased during pubertal development, being 375 +/- 32, 117 +/- 15 and 44 +/- 7 fmol/mg DNA in 7-, 21- and 35-day-old rats respectively, whereas the affinity of binding, as evaluated by the dissociation constant (Kd), did not change. Early induced hypothyroidism significantly affected the time-course of the postnatal decline of nuclear T3 receptors in the testis. At 21 days of age, the binding capacity for T3 in the testis of methimazole-treated rats was significantly higher with respect to euthyroid controls, being 173 +/- 21 and 117 +/- 15 mol/mg DNA respectively, while the Kd was unaffected. T3 replacement therapy completely prevented changes in T3 receptor number induced by hypothyroidism without modifying the Kd. Our results indicate that nuclear T3 receptors in the developing rat testis are modulated by thyroid hormone.

Animals↗