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Biomedical subjects

S Bernardini

Publications and source records attributed to S Bernardini.

At least 73 records · Page 4Linked to original sources
PubMed1997

Salt depletion and dehydration in hypertensive preterm infants.

Three preterm infants presented with both severe or moderate arterial hypertension and dehydration due to increased water and sodium urinary excretion. In patient 1, water and sodium wasting were extremely severe and peaked at 575 ml/kg per day and 73 mEq/kg per day, respectively. In all infants, urinary water and sodium excretion dramatically decreased when hypertension resolved. The overall clinical data suggest a pressure natriuresis phenomenon.

Antihypertensive Agents↗
PubMed1997

Effects of cisapride on QTc interval in neonates.

AIM: Prospective survey of the effects of cisapride on QTc interval in neonates given cisapride. METHODS: QTc interval was determined just before and 2.9 (0.9) days after outset of the treatment in 49 neonates treated with cisapride between 1 August 1995 and 29 February 1996. RESULTS: Cisapride significantly increased QTc interval (p = 0.0001), and this was higher when birthweight or gestational age were lower. The prolongation of QTc interval above the arbitrary value of 0.450 (n = 7) was clinically asymptomatic and was significantly more common in the infants born with a gestational age < or = 33 weeks (n = 6). CONCLUSION: The findings indicate that cisapride accumulates in less mature neonates. Further pharmacokinetic studies are needed.

Cisapride↗
PubMed1996

Induction of sister chromatid exchange by 3,4-expoxybutane-1,2-diol in cultured human lymphocytes of different GSTT1 and GSTM1 genotypes.

The induction of sister chromatid exchanges (SCEs) by a 48-h treatment with 3,4-epoxybutane-1,2-diol (EBD), a metabolite of 1,3-butadiene, was studied in whole-blood lymphocyte cultures of 22 human donors with known genotypes of two polymorphic glutathione S-transferases (GSTs), GSTT1 and GSTM1. For both genes, donors representing a homozygous 'null' genotype lacking the respective GST gene and isozyme and a 'positive' genotype with at least one intact gene and GST activity were included. The mean frequencies of SCE/cell were similar in all genotype groups: GSTT1 null (n = 10) (mean 22.0 for 250 microM and 32.9 for 500 [corrected] microM of EBD), GSTT1 positive (n = 14) (21.3 and 34.6, respectively), GSTM1 null (n = 10) (20.3 and 33.5) and GSTM1 positive donors (n = 15) (20.6 and 34.8). At 500 microM concentration of EBD, the lymphocyte cultures of all donors showed a significantly decreased replication index. No differences in EDB-induced SCEs or in replication index could be associated with the GSTM1 and GSTT1 genotypes either separately or in combination. When SCE induction by EBD was compared to that of two other known epoxide metabolites of butadiene, 1,2:3,4-diepoxybutane (DEB) was effective at concentrations over two orders of magnitude lower than EBD or 1,2-epoxy-3-butene (MEB). It is concluded that EBD is an efficient inducer of SEC in cultured human lymphocytes, although not quite as effective as MEB and clearly less effective than DEB. Contrary to previous findings with DEB and MEB, the polymorphic GSTM1 and GSTT1 do not appear to be involved in the detoxification of EBD in human lymphocytes.

Adult↗
PubMed1996

Morphogenesis and differentiation of grafted blastemas formed in vitro from amputated hindlimbs of larval Xenopus laevis.

The present study was designed to test the morphogenetic potency of limb blastemas formed in vitro from amputated limbs of larval Xenopus laevis. Hindlimbs of larvae at stage 55 (according to Nieuwkoop and Faber [1956] Normal Table of Xenopus laevis (Daudin)) were amputated through the tarsalia, excised at the base of the thigh and cultured in Leibovitz's L-15 supplemented with 2% FCS. After 8-10 days, 50% of the cultured limbs formed a conic blastema on the amputation surface. However, on the excision surface no blastema was present. Three different parts (blastema, blastema with the shank region and proximal part of the limb) of the cultured limbs were then grafted to the axial musculature or to the hindlimb of stage 57 host larvae. Results showed that the blastema formed in vitro were true autodifferentiating regeneration blastemas, since they were able to form well-differentiated autopodia not only when grafted with the shank region to a neutral territory (axial musculature) or to the limb territory, but also when transplanted alone to the two environments. The morphological complexity (no. of toes) of the autopodia differentiated from the grafted blastemas was superimposable to that observed in vivo. Moreover, as in vivo, the entire regeneration process was nerve-independent. In fact, the regeneration blastemas, formed in vitro in the complete absence of nerves, could grow and differentiate also when grafted to denervated host limbs. The grafted proximal parts of the cultured limbs never formed a regenerate.

Animals↗
PubMed1996

Mechanisms of transcriptional activation of the promoter of the rainbow trout prolactin gene by GHF1/Pit1 and glucocorticoid.

The transcription factor GHF1/Pit1, required for the expression of the prolactin (PRL) and other pituitary-specific genes, is highly conserved from fish to mammals but the mechanisms by which it activates transcription are poorly understood. The activity of the promoter (-627/+15 region) of the rainbow trout PRL (tPRL) gene fused to the luciferase reporter gene was studied using GHF1-expressing rat pituitary GC cells. Nuclear extracts of GC cells produced five GHF1-specific footprints in the tPRL promoter, with the position of the two most proximal ones being highly conserved in trout and mammalian GHF1-regulated genes. Deletional and mutational analyses of the tPRL promoter showed that the most proximal GHF1 site alone is sufficient to confer sub-maximal GHF1-dependent transcriptional activity and that a glucocorticoid response element-like motif mediates dexamethasone stimulation. It is suggested that GHF1 molecules bound to different sites of the tPRL promoter cannot interact simultaneously with the transcriptional apparatus. Moreover, GHF1 and the ligand-bound glucocorticoid receptor tethered to their cognate elements in the promoter could cooperate to enhance transcription by interacting simultaneously with different members of the basal transcriptional complex.

Animals↗
PubMed1996

A TGACG motif mediates growth-hormone factor-1/pituitary-transcriptional-activator-1-dependent cAMP regulation of the rainbow trout growth-hormone promoter.

The mechanisms involved in the regulation of the rainbow trout growth hormone (tGH) gene promoter by the pituitary-specific transcription factor GHF1 (growth hormone factor 1), also called Pit1 (pituitary transcriptional activator 1), and cAMP have been investigated in mammalian and fish cells. The -340 to +24 5'-flanking Fegion of the tGH gene focused to the luciferase gene was activated in rat pituitary GC cells and in HeLa cells cotransfected with an effector plasmid encoding rat GHFI. GC cell nuclear extracts produced four GHFI-specific footprints (sites Fl to F4) on the tGH promoter, each containing multiple W4NCAT (W, A or T) or closely related motifs. Mutational analysis performed in GC cells indicated that the proximal Fl site alone can direct transcription, but that the region encompassing the F2 and F3 sites is necessary for optimal activation and contains a TGACG motif (cAMP-response element, CRE) conferring cAMP responsiveness. The role of the TGACG motif in mediating cAMP regulation of the tGH promoter was confirmed in primary cultures of trout pituitary cells. Cotransfection studies in carp EPC cells using an effector plasmid encoding trout GHF1 demonstrated the GHF1 dependence of cAMP stimulation. Gel shift and southwestern experiments revealed nuclear proteins of 43 kDa and 30 kDa in GC and fish cells, respectively, that bind specifically to the tGH CRE, suggesting the involvement of CRE-binding-protein/activating-transcription-factor-l-related peptides in cAMP response. Incidentally, and in contrast with previous reports, we found the rat GH promoter, that lacks TGACG motifs, unresponsive to cAMP. Thus, the CAMP stimulation of the tGH gene is more similar to its human counterpart. that is also GHF1 dependent and mediated by TGACG motifs in the promoter. It is suggested that control of GH gene expression has evolved modularly, through various assortments of the same regulatory units, rather than molecularly, through innovative units.

Animals↗
PubMed1996

Effect of ammodytin L from the venom of Vipera ammodytes on Xenopus laevis differentiated muscle fibres and regenerating limbs.

Ammodytin L is a non-catalytic, phospholipase-like snake venom toxin from Vipera ammodytes, which shows a cytotoxic activity on differentiated myotubes when tested in vitro. In the range of concentrations in which ammodytin L induced necrosis of myogenic cells in culture, other cell types (erythrocytes, platelets, fibroblasts) did not appear to be affected. To test the in vivo toxicity and the effective cytolytic specificity of ammodytin L we have followed the morphological changes in muscle tissue of Xenopus laevis limbs after intramuscular toxin injection. Only muscular cells were affected by ammodytin L, and the toxin did not induce any morphological change in other cell types. Further evidence of the muscle-specific action of the toxin was obtained from experiments carried out using the Xenopus kidney cell line B3.2 in culture. Ammodytin L was unable to affect parameters of cell viability such as lactate dehydrogenase leakage, [3H]thymidine incorporation, growth curves and morphological changes. Moreover, direct ammodytin L application to cultured regenerative limbs did not provoke alterations in undifferentiated myoblasts. These data suggest that ammodytin L, like other phospholipase-like toxins, exerts its toxicity by selectively damaging differentiated muscle fibres.

Animals↗
PubMed1996

Regulation by retinoic acid of insulin-degrading enzyme and of a related endoprotease in human neuroblastoma cell lines.

Physiologically, the action of insulin-like growth factors (IGFs) is controlled at different levels, from its transcription start by tissue-specific and development-specific transcriptional factors to its degradation by peptidases such as insulin-degrading enzyme (IDE). Since IGF-II is the major autocrine/paracrine growth factor for neuroblastoma cells, we studied the expression and the role of IDE in this system. Here, we show that (a) IDE is expressed in several human neuroectodermal tumor cell lines, including neuroblastoma cell lines; (b) in a neuroblastoma cell line, IDE expression is up-regulated by retinoic acid, a well-known inducer of neuronal differentiation and/or programmed cell death; (c) IDE is probably not the only IGF-degrading enzyme present in these cells, since the activity of a novel thermolysin-like metalloendopeptidase, clearly distinct from IDE, is also detected. The TME activity is inhibited by IGF-I, Des-IGF-I, and IGF-II, and it is down-regulated by retinoic acid. Since retinoic acid plays a relevant role in controlling the growth of these cells and affects the expression of IDE, we have also: (a) identified the retinoic acid receptors (RARs) and retinoid X receptors (RXRs) expressed in these cell lines and (b) by means of synthetic retinoid analogues identified the RAR/RXR isoforms whose activation may be sufficient to induce the expression of the IDE gene. These results provide evidence that complex posttranslational molecular mechanisms participate in the autocrine/paracrine growth control of the IGF-II loop in neuroblastomas involving proteolytic systems.

Endopeptidases↗
PubMed1995

Acquisition of nerve dependence for the formation of a regeneration blastema in amputated hindlimbs of larval Xenopus laevis: the role of limb innervation and that of limb differentiation.

In larval and adult urodeles and late-stage larval anurans, blastema formation after limb amputation requires an adequate nerve supply. Experimental evidence obtained from aneurogenic limbs indicates that, in urodeles, the acquisition of nerve dependence during embryonic development is due to the "addiction" of limb tissues to factors released by the ingrowing nerves rather than to limb differentiation. The aim of this work was to establish whether, in the toad Xenopus laevis, nerve-dependence for blastema formation after hindlimb amputation, which is acquired gradually during larval development and becomes complete at stage 57 is due to limb innervation or to limb differentiation. Two series of experiments were carried out. In the first series, limb differentiation was inhibited by treating the larvae with an anti-thyroid drug, and innervation was maintained for an interval much longer than that normally required for development from nerve-independent stages to stage 57. In the second series, the limb was caused to differentiate in the absence of nerves by maintaining the limbs denervated. Limb differentiation was often accelerated by treating early-stage larvae with thyroxine or by grafting early-stage limbs onto denervated limbs of late larvae, which, being near metamorphic climax, possessed high levels of circulating thyroid hormones. Results showed that in the first series of experiments the denervated limbs formed regeneration blastemas after amputation, but in the second series they did not. It was therefore concluded that the acquisition of nerve dependence for blastema formation in larval Xenopus laevis is not directly imposed by factors released by the nerve fibers, but is strongly related to differentiation of limb tissues.

Amputation, Surgical↗
PubMed1995

Exogenous growth hormone administration does not inhibit the growth hormone response to hexarelin in normal men.

Administration of exogenous human growth hormone (GH) blunts the GH response to physiological as well as pharmacological stimuli, including GH-releasing hormone (GHRH). Hexarelin (Hex) is a new synthetic GH-releasing peptide (GHRP) similar to GHRP-6 with potent GH-releasing activity in animals and men. To determine whether the short-term administration of GH inhibits the Hex-induced GH release, we measured the GH response to Hex (2 micrograms/kg iv) in five normal adult males (age 26-32 yr) three h after an iv bolus of rhGH (2 IU) or saline. Mean incremental change of serum GH from value at time 0 was 47.5 +/- 5.5 and 41.5 +/- 4.1 micrograms/l after saline + Hex and GH + Hex, respectively. Mean incremental area under the curve over baseline was 3216 +/- 586 and 3735 +/- 506 micrograms.min.1 after saline + Hex and GH + Hex, respectively. One of the proposed mechanism of action of GHRPs is to serve as functional somatostatin (SRIH) antagonists, and it is known that GH feeds backs on the hypothalamus to stimulate SRIH release. Therefore, we speculate that antagonisms of SRIH function by Hex prevented the inhibitory effect of exogenous GH, thus lending further support to the hypotheses that SRIH is involved in the feedback regulation of GH secretion, and that GHRPs action involves inhibition of SRIH function.

Adult↗
PubMed1995

The inhibition of cell proliferation by mitomycin C does not prevent transdifferentiation of outer cornea into lens in larval Xenopus laevis.

The aim of the present work is to evaluate the relationship between cell proliferation and transdifferentiation (TS) of the outer cornea into lens in larval Xenopus laevis. Data obtained from corneal fragments treated with Mitomycin C (MMC) (0.1 mg/ml, 50 min) and implanted into the vitreous chamber (MMC/v ch) were compared with those obtained from untreated corneal fragments implanted into the vitreous chamber (contr/v ch) or between outer and inner corneas (contr/o c). Results demonstrated that in contr/v ch implants, which transdifferentiated into lenses or lentoid bodies in 88% of cases, the mitotic index (MI) showed a sharp increase during the period of lens vesicle formation (3 days) and became very low when the formation of lens fibres was under way (7 days). In contro c implants, which did not undergo any lens forming transformations, the MI remained unchanged in comparison to time O. In MMC/v ch implants, the inhibition of the mitotic activity was 100% up to the third day after implantation. On the fifth and seventh days, scant mitotic activity was observed in some cases, but the MI was much lower than the MI of contr/o c implants. The MMC/v ch implants transdifferentiated into lentoid bodies in 26% of cases. The lentoid bodies were much smaller than those observed in control implants, but they reacted positively with the lens antibodies at the same time after implantation as controls. Even the complete inhibition of proliferation due to stronger MMC treatments (e.g. 0.15 mg/ml, 50 min) did not prevent lens TS.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

[Uretero-vesival rupture with vaginal fistula following pelvic fracture. Value of early diagnosis and emergency surgery].

Traumatic fracture of the pelvis led to the rare combination of urethra and bladder rupture and fistulization into the vagina. This unusual lesion can go undiagnosed initially and must be properly identified during the emergency gynaecology and urology examination. Tissue damage involved nearly the entire length of the urethra including both the smooth and striated sphincters. Reconstructive surgery produced good anatomic and functional results.

Accidents, Traffic↗
PubMed1995

Differences in the decrease in regenerative capacity of various brain regions of Xenopus laevis are related to differences in the undifferentiated cell populations.

The extent of the undifferentiated cell population in normal and regenerating brains of larvae and metamorphosed individuals of Xenopus laevis has been analyzed by means of an immunocytochemical method and mitotic index determinations. Results show that the decrease in regenerative capacity of the brain during larval development and after metamorphosis is in relation with the gradual reduction of the population of undifferentiated cells and that the different regenerative capacities of the various brain districts are related to quantitative and qualitative differences in this cell population. While in the early larval stages the cell population formed of actively cycling cells is very large and widespread, in late larval stages and after metamorphosis these cells localize in some encephalic areas (matrix zones). This localization occurs later in the telencephalon than in the rhombencephalon and in mesencephalon. The less conspicuous decrement in the regenerative capacity of the telencephalon than of other encephalic districts of froglets, particularly the mesencephalon, is related to the presence of a larger number of actively cycling cells together with a rather large number of undifferentiated cells which are in a temporary quiescent state from which they may re-enter the actively cycling state in response to proliferation promoting factors.

Animals↗
PubMed1995

Medullary and gangliar regeneration after unilateral removal of a segment of spinal cord of the trunk and corresponding ganglion in adult newts.

Regeneration of the spinal cord, segmental nerves and sensory ganglia takes place after tail amputation in the newt. Many histological and immunocytochemical observations provide evidence that the ependymal tube is the source not only of new neurons and glial cells in the spinal cord, but also of some cells that go on to participate in the formation of the spinal ganglia of the regenerating tail. In previous experiments involving the removal of the spinal ganglia of the trunk, no regeneration was observed and it is thought that the trunk region differs from the tail region with regard to the ability to regenerate sensory ganglia. However, in these experiments the spinal cord of the trunk was not damaged. In the present work involving adult newts (Triturus carnifex Laur.), unilateral ablation of a segment of the spinal cord of the trunk in addition to removal of a corresponding spinal ganglion was performed. In these experimental conditions, regeneration of a rudimentary spinal ganglion near the regenerated side of the spinal cord segment was observed in several cases. Histological observations carried out 2, 4, 6 and 13 months after the operation support the view that some cells migrating from the lateroventral part of the regenerating side of the spinal cord via the developing ventral root could participate in the formation of the rudimentary spinal ganglion.

Amputation, Surgical↗
PubMed1995

[Surgery for severe traumas of the kidney. Value of initial computed tomography, problem of surgical indication and use of a perirenal resorbable prosthesis of polyglactin 910].

We report our recent experience in the surgical treatment of severe closed renal trauma, describing the value of the initial tomography scan, the problems encountered with indications for surgery, and use of a resorbable peri-renal prosthesis made of polyglactine 910. During the last 4 years, 41 patients were hospitalized for renal trauma. Eleven of these patients were operated for severe lesions (Chatelain stage 3 and 4). Surgical treatment was as conservative as possible: total organ repair was possible in 5 cases and partial repair in 3, the kidney was lost in 3 cases.

Accidents, Occupational↗
PubMed1994

Expression and down-regulation by retinoic acid of IGF binding protein-2 and -4 in medium from human neuroblastoma cells.

Insulin-like growth factors (IGFs) regulate the autocrine/paracrine growth of neuroblastomas. The IGFs bind to specific binding proteins (IGFBPs) which modulate their biological activity. We investigated, by Western ligand blotting (WLB), the presence of IGFBPs and their possible modulation by retinoic acid (RA), IGF-I, IGF-II and truncated Des(1-3)IGF-I in conditioned medium (CM) of the human neuroblastoma SK-N-BE(2) cell line. We demonstrated the presence of two IGFBPs, with MW 37 kDa and 25 kDa. Following immunoprecipitation, they turned out to be IGFBP-2 and -4, respectively. The RA-induced differentiation in SK-N-BE(2) cells was accompanied by a marked reduction of the intensity of both IGFBP bands after 48 h (32% and 24% of control, respectively) and 72 h (2% and 0% of control, respectively) incubation. The addition of exogenous IGFs, which did not induce cell differentiation, did not change the IGFBP pattern significantly, except for the truncated form of IGF-I, which induced a marked decrease in both the 37 kDa and 25 kDa bands after 72 h incubation (45% and 18% of control, respectively). These findings suggest that IGFBPs have a role in RA-induced differentiation in human neuroblastoma cells.

Blotting, Western↗
PubMed1994

Reduced growth hormone secretion in Turner syndrome: is body weight a key factor?

The age-related decline in spontaneous growth hormone (GH) secretion has been suggested to cause growth failure in girls with Turner syndrome (TS). We studied 23 girls (mean age +/- SD: 11.1 +/- 2.7 years) diagnosed to have TS by karyotype analysis. The control group consisted of 18 prepubertal age-matched subjects (10.7 +/- 2.5 years) with growth retardation due to familial short stature and/or constitutional growth delay. In addition, 18 children (10.9 +/- 3.3 years) diagnosed to have GH deficiency by two different provocative tests were chosen as a further comparison group. Spontaneous 12-hour nocturnal GH secretion was assessed by RIA at 30-min intervals. Plasma insulin-like growth factor 1 (IGF-1) levels were determined by RIA after acid-ethanol extraction. Girls with TS had a percentage of ideal body weight significantly higher than controls (p < 0.0001) and showed spontaneous GH secretion significantly lower than controls (mean +/- SD: 3.2 +/- 1.6 in TS vs. 5.5 +/- 1.3 microgram/l in controls; p < 0.0001) but higher than GH-deficient patients (1.3 +/- 0.8 microgram/l; p < 0.0001). No significant difference was found in IGF-1 levels between TS patients and controls, whereas GH-deficient children showed IGF-1 levels significantly lower than those of TS patients (p < 0.0005). As expected, GH concentrations correlated with bone age in controls (r = 0.51, p < 0.05), whereas no relationship was seen in TS. interestingly, in TS, GH levels were negatively related to the percentage of ideal body weight (r = -0.43, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗