Biomedical subjects

L Vergani

Publications and source records attributed to L Vergani.

At least 37 records · Page 2Linked to original sources

PubMed1997

Glycosaminoglycan supplementation promotes nerve regeneration and muscle reinnervation.

This study shows that treatment of rats with exogenous glycosaminoglycans stimulates peripheral nerve regeneration, increases the abundance of mRNAs for myelin proteins and promotes muscle reinnervation. After the sciatic nerve had been crushed the number of regenerating axons in the distal stump was markedly and highly significantly increased by glycosaminoglycan treatment throughout the experimental period. The increased number of axons was correlated with increased axon and fibre (axon+myelin) diameter. The abundance of mRNAs for P0 protein and myelin basic protein of regenerating nerves was also affected by treatment with glycosaminoglycans. The increase in mRNA was also observed in the contralateral unlesioned nerve. Such a phenomenon did not occur in saline-treated rats. Glycosaminoglycan treatment markedly increased the number of muscle fibres reinnervated and accelerated the restoration of muscle twitch tension elicited by nerve stimulation. The effect was particularly evident during the early stages (16 and 21 days after nerve crush) of muscle reinnervation.

Animals↗

PubMed1996

Glycosaminoglycans in nerve injury: II. Effects on transganglionic degeneration and on the expression of neurotrophic factors.

Injury to the sciatic nerve leads to the transganglionic degeneration of sensory axons and to the induction of neurotrophins and p75 nerve growth factor receptor synthesis by the denervated Schwann cells. Sciatic nerve axotomy caused a marked loss of substance P and of met-enkephalin in the lumbar cord. Substance P immunostaining and pre-proenkephalin mRNA expression were reduced in the dorsal horn layers I and II ipsilaterally to the lesion. Treating rats with low doses (0.25 mg/kg) of heparin or COS 8, a natural glycosaminoglycan mixture with low anticoagulant activity, the peptide loss was prevented and the content increased of about 50% above control values. The effects of COS 8 treatment were also evident on Schwann cells. COS 8 augmented the increase of nerve growth factor, brain-derived neurotrophic factor, and NT-3 mRNA expression in the distal stump of the axotomized sciatic nerve. Therefore, it can be concluded that glycosaminoglycans neuroprotective effects on lesioned sensory axons might have been mediated by the dramatic promotion of neurotrophin synthesis. Although the in vitro studies (Lesma et al.: J Neurosci Res, 1996) suggested also a likely direct effect as extracellular matrix components that is not mediated by trophic factors.

Animals↗

PubMed1996

Perinatal exposure to morphine: reactive changes in the brain after 6-hydroxydopamine.

The effects of neonatal 6-hydroxydopamine treatment on the brain of control rats and of rats perinatally exposed to morphine were examined. Noradrenaline levels were increased in the pons-medulla, mesencephalon and caudate of 8-week-old control rats lesioned with neonatal 6-hydroxydopamine; perinatal morphine treatment prevented such an increase. In the caudate, there was a loss of dopamine and an increase of serotonin following the neurotoxic lesion; exposure to perinatal morphine prevented the serotonin increase. Brain expression of synapsin I mRNA was particularly abundant in cerebral cortex, hippocampus, dentate gyrus and olfactory bulb. In perinatal morphine-treated rats, the expression of synapsin I mRNA was significantly reduced; interestingly, the neonatal treatment with 6-hydroxydopamine normalized its expression. Therefore, brain-reactive neurochemical changes triggered by 6-hydroxydopamine were suppressed by perinatal morphine exposure whereas the association of morphine exposure and 6-hydroxydopamine lesion promoted the normal mRNA expression of the synaptic marker synapsin I.

Adrenergic Agents↗

PubMed1996

Effect of fixatives on calf thymocytes chromatin as analyzed by 3D high-resolution fluorescence microscopy.

Two common fixatives--glutaraldehyde and ethanol/acetic acid mixture--were studied to understand their effects on DNA distribution inside the cell nucleus. Native calf thymocytes were analyzed by using a DNA selective fluorescent dye (DAPI) and computational optical sectioning microscopy on isolated cells before and after fixation. In order to estimate quantitatively the intranuclear DNA distribution, the stained calf thymocytes images were processed by removing the out-of-focus contributions present in each optical section. Although preliminary, the results show that within individual nuclei the frequency distribution of the fluorescence intensity appears significantly and differentially altered by the two fixatives. Namely with respect to the native unfixed preparation, the ethanol/acetic acid causes the complete disappearance of the higher intensity pixels, whereas glutaraldehyde fixation can be associated with the appearance of new ones of an even higher intensity. The quantitative analysis of the processed images allowed us to reconstruct the topological distribution of DNA inside the nucleus and to correlate the data with the results obtained by differential scanning calorimetry on similar samples.

Acetates↗

PubMed1996

Residual muscle cytochrome c oxidase activity accounts for submaximal exercise lactate threshold in chronic progressive external ophthalmoplegia.

The data from histological, biochemical, and mitochondrial DNA (mtDNA ) studies of muscle biopsies from 10 patients affected with chronic progressive external ophthalmoplegia (CPEO) were related to dynamic and metabolic parameters of incremental submaximal exercise. Maximum power output was reduced in all patients as compared to controls. Analysis of the venous lactate curve during exercise revealed a lactate threshold at exercise levels ranging from 40 to 50% of the predicted maximal power output. An earlier significant increase in lactate could be detected by calculating the mean delta lactate. Lactate values were inversely correlated with the cytochrome c oxidase (COX) activity of isolated muscle mitochondria. No relationship was found between lactate values and the number of ragged red fibers, or cytochrome c oxidase-negative fibers of the proportion of deleted mtDNA measured in muscle biopsy specimens. The discussion underscores the value of lactate kinetics in assessing skeletal muscle function, as well as the use of muscle COX levels to predict the effectiveness of wild-type complementation of deleted skeletal muscle mtDNA in in vivo contractile performance of CPEO subjects.

Adult↗

PubMed1996

Molecular characterization of myophosphorylase deficiency in a group of patients from northern Italy.

We studied a group of 14 patients from Northern Italy with myophosphorylase deficiency. The disease presented considerable clinical and biochemical heterogeneity, which was reflected at the molecular level. The clinical presentation was typical in 3 patients, mild in 7 (exercise intolerance), and severe in 4 (fixed weakness). Enzyme activity was undetectable in 10 patients, below 3% of control in 3, and 13% of control in one. Enzymatic protein was detectable immunologically only in 1 patient. Myophosphorylase mRNA was present in 8 patients, but in 7 of them it was reduced in amount. Two patients were homozygous for the common nonsense R49X mutation, 5 were heterozygous. Two missense mutations not previously observed were identified in this group of patients. The frequency of alleles with the R49X mutation was significantly lower in this group of patients than in previously reported series. Myophosphorylase deficiency is genetically heterogeneous even among patients living in a small region and with a common ethnic background.

Adolescent↗

PubMed1996

Exposure to perinatal morphine promotes developmental changes in rat striatum.

This study shows that perinatal exposure to morphine promotes developmental changes (up to 8 months of life) in the striatum by up-regulating concentrations of substance P and met-enkephalin with changes of prometenkephalin A mRNA expression at the day of birth only. Dopamine metabolism (up to 60 days) is also increased as suggested by the reduced concentrations of dopamine and increased content of 3,4-dihydroxyphenylacetic acid. Tyrosine hydroxylase mRNA expression is selectively reduced only in the substantia nigra by perinatal morphine. Serotonin content is reduced only during the early postnatal days and is unaffected thereafter. Supplementation of naltrexone to morphine-exposed rats prevents monoaminergic and neuropeptidergic changes in the striatum, which directly implicates opioid receptors in the developmental changes caused by morphine. The data suggest that perinatal morphine may inhibit met-enkephalin release, causing accumulation of the peptide without corresponding changes in specific mRNA. Dopamine release may also be increased as indicated by a higher metabolism and consequent reduction of tyrosine hydroxylase mRNA expression in the substantia nigra.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1995

Perinatal morphine. I: Effects on synapsin and neurotransmitter systems in the brain.

We have previously shown that rat perinatal exposure to morphine causes dopaminergic and met-enkephalin (ME) and substance P (SP) changes in the striatum during the early postnatal period (Tenconi et al.: Int J Dev Neurosci 10: 517 - 526, 1992); in addition it increases the susceptibility to neurotoxic lesions and impairs regenerative capacity of the serotoninergic system (Gorio et al.: J Neurosci Res 34: 462 - 471, 1993). Our study shows that ME and SP levels increase postnatally in several areas of the rat brain, reaching the highest values between 30 and 60 days, after which the peptide content subsides to lower levels. Perinatal exposure to morphine increases such ME and SP levels during the early stages of postnatal life. No effect of morphine on 5-HT and NE is observed, while the dopaminergic system is mainly affected in the mesencephalon. The pre- and postnatal brain expression of synapsin I mRNA is gradually and progressively localized in discrete areas of the brain. In the brain of rats perinatally exposed to morphine, the abundance of synapsin I mRNA expression is markedly reduced. Therefore, perinatal exposure to morphine affects early postnatal synaptic development in the brain as shown by the altered peptidergic and monoaminergic content and by the reduced synapsin I mRNA expression.

Animals↗

PubMed1995

MtDNA mutations associated with Leber's hereditary optic neuropathy: studies on cytoplasmic hybrid (cybrid) cells.

Leber's hereditary optic neuropathy (LHON) has been associated with "primary" and "secondary" mtDNA missense point mutations, and a synergistic role has been proposed for secondary mutations. No previous study has investigated the effects of LHON primary or primary plus secondary mutations on the respiratory competence of cell lines. We constructed and compared cybrid cell lines obtained from two unrelated LHON patients both carrying the common 11778/ND4 primary mutation. One of the patients also carried the 13708/ND5 and 4216/ND1 secondary mutations. The cybrid clones were evaluated for growth efficiency, oxygen consumption, complexes I, III and IV enzymatic activity and mitochondrial protein synthesis. Complex activity and mitochondrial protein synthesis were not significantly changed in cybrid clones from the patients. Oxygen consumption was significantly decreased in all clones carrying the 11778/ND4 primary mutation demonstrating its pathogenic role in impairing cell respiration. Clones also carrying the secondary mutations showed an even lower oxygen consumption and a significantly higher doubling time, suggesting that the co-presence of the secondary mutations could be relevant in further reducing the cell fitness.

Adult↗

PubMed1994

Ethidium bromide intercalation and chromatin structure: a spectropolarimetric analysis.

Native chromatin has been characterized at different ionic strengths, according to different methods of preparation, by means of circular dichroism and ethidium bromide intercalation. For a more precise interpretation of these results, a series of analogous experiments on phagic DNA, as a function of its circularization, and on mononucleosomes have been performed. Results are discussed here in terms of high order chromatin structure, DNA supercoiling, and topological constraints.

Animals↗

PubMed1993

Expression of muscle-type phosphorylase in innervated and aneural cultured muscle of patients with myophosphorylase deficiency.

Patients with McArdle's myopathy lack muscle glycogen phosphorylase (M-GP) activity. Regenerating and cultured muscle of patients with McArdle's myopathy presents a glycogen phosphorylase (GP) activity, but it is not firmly established whether M-GP or non-M-GP isoforms are expressed. We have cultured myoblasts from biopsy specimen of five patients with McArdle's myopathy. Skeletal muscle was cultured aneurally or was innervated by coculture with fetal rat spinal cord explants. In the patients' muscle biopsies and in their cultured innervated and aneural muscle we studied total GP activity, isoenzymatic pattern, reactivity with anti-M-GP antiserum, and presence of M-GP mRNA. There was no detectable enzymatic activity, no immunoreactivity with anti-M-GP antiserum, and no M-GP mRNA in the muscle biopsy of all patients. GP activity, M-GP isozyme, and anti-M-GP antiserum reactivity were present in patients' aneural cultures, increased after innervation, and were undistinguishable from control. M-GP mRNA was demonstrated in both aneural and innervated cultures of patients and control by primer extension and PCR amplification of total RNA. Our studies indicate that the M-GP gene is normally transcribed and translated in cultured muscle of patients with myophosphorylase deficiency.

Adult↗

PubMed1993

Hypertrophic cardiomyopathy with mitochondrial myopathy. A new phenotype of complex II defect.

Two brothers, 25 and 19 years old, were affected by asymmetrical hypertrophic cardiomyopathy. The older brother had waddling gait and weakness of the proximal girdle muscles, while the younger had a broad-based gait and weakness of selected limb girdle muscles. EMG exam was myopathic. Serum enzyme, CPK and aldolase were elevated. Histochemical reactions in muscle revealed "core-like" areas, subsarcolemmal rims of mitochondria and lipid accumulation. Succinate-dehydrogenase stain showed a lack of activity in both biopsies, with the exception of intrafusal fibers. Microphotometric quantitative measurements confirmed the defect in both biopsies. Biochemical measurements of several mitochondrial enzymes in muscle showed a reduced activity of succinate-dehydrogenase (33%) and succinate-cytochrome C reductase (36-47%) which are both components of complex II. On myocardial biopsy lipid and mitochondrial abnormalities were found. This mitochondriopathy represents a new phenotype of partial complex II defect.

Adult↗

PubMed1992

Fluorescence cytometry of microtubules and nuclear DNA during cell-cycle and reverse-transformation.

Synchronized CHO-K1 cells and their dibutyryl c-AMP treated counterparts have been characterized by means of static and flow fluorescence cytometry at the level of nuclear DNA and cytoplasmic microtubules. In order to confirm earlier findings on synchronized population, Carnoy fixed and hydrolyzed, several new findings are here reported at the level of single intact cell. The fluorescence intensity of DAPI-stained glutaraldehyde fixed 2C cells correlates well with the average absorbance of the corresponding Feulgen-stained cells, thereby appearing also to be a measure of chromatin condensation during the G1 phase. In the early part of G1, the drastic alteration in anti-beta tubulin immunostaining is shown to parallel microtubule depolymerization induced by calcium or colcemide. The known 1-2 h lengthening of the G1 period after reverse-transformation appears to correlate with a similar delay in the abrupt chromatin decondensation. The above results are discussed in terms of the role of microtubules and nuclear morphometry (and their coupling) in the control of cell cycle progression of transformed vs. fibroblast-like cells.

Animals↗

PubMed1992

Clinical and biochemical aspects of carnitine deficiency and insufficiency: transport defects and inborn errors of beta-oxidation.

Carnitine is required for entry of long chain fatty acids into mitochondria where beta-oxidation occurs. Primary carnitine deficiency, due to a generic defect in cellular carnitine transport, exists in myopathic and systemic forms. Secondary carnitine deficiency may be due to multiplicity of inherited abnormalities, including deficiencies in carnitine palmitoyl-transferase acyl-CoA dehydrogenases, electron transfer flavoprotein, and 3-ketoacyl-CoA-thiolase. The clinical features, diagnosis, and treatment of these conditions are described.

Biological Transport, Active↗

PubMed1991

L-carnitine uptake in differentiating human cultured muscle.

We studied carnitine uptake in human skeletal muscle growing in culture for up to 30 days, and correlated it to the degree of muscle differentiation revealed by myotube formation and muscle-specific creatine-kinase isozyme accumulation. In our study carnitine uptake was a saturable specific process with two distinct components: a high affinity uptake at carnitine concentration between 0.5 and 10 microM and a low affinity uptake at carnitine concentration between 25 and 200 microM. High affinity uptake (Km 4.17-5.50 microM, Vmax 11.78-19.6 pmol/h per mg protein) did not change during muscle maturation in culture. Low affinity uptake showed significant changes in Km and Vmax in the various stages of muscle differentiation. Our studies suggest the existence of a muscle-specific system, operating at physiological carnitine concentration, which gradually develops during muscle maturation in culture. We hypothesize that a defect of the low affinity muscle-specific uptake might be the cause of the primary muscle carnitine deficiency syndrome.

Adult↗

PubMed1991

Changes in DNA superhelical density monitored by polarized light scattering.

Linear and circular lambda-DNA at different ethidium bromide concentrations have been studied by means of polarized light scattering, namely the S14, S34, S33 and S13 elements of Mueller matrix. While S33 at low angle appears well correlated with the total light scattering evaluated by optical density measurements at 632.8 nm for linear and circular DNA of the same mass, the magnitude and slope of the S14, S34 and S13 signals display significant changes for the circular lambda-DNA depending on the degree of negative superhelical density as induced by the different ethidium bromide concentrations. At the same time, for linear lambda-DNA the signal remains invariant, making explicit for the differential scattering of polarized light the possibility to obtain additional information by its angular dependence. Strikingly also the effect of 0.2% glutaraldehyde versus ethanol fixation on the native lambda-DNA structural properties appears to confirm earlier findings by other well-established probes. Results are discussed in terms of first physical principles and of their potential bearings towards our understanding of the mechanism controlling gene expression.

Bacteriophage lambda↗

PubMed1991

Polarized light scattering of nucleosomes and polynucleosomes--in situ and in vitro studies.

Nucleosomes, chromatin and nuclei, extracted from rat hepatocytes, are studied by a new "in house" experimental configuration which measures circular intensity differential scattering (CIDS) and other elements of the polarized light scattering matrix. The Mueller matrix elements, S14 and S34, that are related to the geometric parameters of the superhelical arrangement of polynucleosomes point to the existence of a quaternary structure at low ionic strength for chromatin prepared by the cold-water method, which is lost by shearing, and is not found in the soluble chromatin prepared through the nuclease method. Only salt addition to a final concentration of 5 mM MgCl2, 150 mM NaCl and 10 mM Tris HCl (pH 7) yields a sizeable (S14 + S34) signal in the latter chromatin, which is however still different from the corresponding signal of native nuclei and of "cold-water" chromatin. Comfortingly, the (S14 + S34) signal from isolated nucleosomes is consistently very low (nearly zero) as predicted by multiple dipole simulation within the framework of classical electrodynamics. Results are discussed in terms of the topological constraints present in the native long chromatin fiber, which are lost after limited nuclease digestion and after shearing.

Animals↗

PubMed1991

Echocardiographic and pulsed Doppler features in glycogen storage disease type II of the heart (Pompe's disease).

Two cases of cardiac glycogen storage disease type II are described: the first one, male aged 3 months, presented with generalized muscular hypotonia and decreased deep tendon reflexes; a 2/6 systolic murmur was audible at the left sternal border; chest X-ray and ECG were consistent with left ventricular hypertrophy; an echocardiogram disclosed an impressive and diffuse cardiac hypertrophy; the pump function appeared preserved and the estimated ejection fraction was about 70%. Pulsed wave Doppler demonstrated a normal envelope of mitral flow with E/A ratio = 1.27 in averaged 20 beats. The patient died suddenly at 6 months of age. The second patient was a female 4 months old with generalized muscular hypotonia. ECG and chest X-ray were consistent with left ventricular hypertrophy; 2D echocardiogram showed diffuse hypertrophy with estimated ejection fraction of 68% and an almost normal aspect of the mitral flow curve, with E/A ratio of 1.18. This child died at 13 months of age of cardiopulmonary insufficiency. In both cases the diagnosis was made by muscular biopsy and biochemical tests (alpha 1-4 glucosidase deficiency). We stress the fact that, despite the severe and diffuse hypertrophy, the pump function and the ventricular filling did not seem compromised.

Cardiomegaly↗