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S Squarzoni

Publications and source records attributed to S Squarzoni.

At least 19 recordsLinked to original sources
PubMed1999

Nuclear changes in a case of X-linked Emery-Dreifuss muscular dystrophy.

Ultrastructural alterations in the nuclear architecture were found in skeletal muscle and skin cultured cells from a patient affected by X-linked Emery-Dreifuss muscular dystrophy (EMD) carrying a null mutation. The molecular defect of X-linked EMD is the absence of emerin, a nuclear envelope-associated protein which is considered a component of the nuclear lamina. The nuclear changes were present in skeletal muscle and skin cultured cells with a frequency of about 10% and 18%, respectively. The main structures of the nuclear periphery were involved: lamina and nuclear envelope-associated heterochromatin were affected, whereas the cisterna and the pore complexes appeared preserved, and the cytoplasm of the same cells appeared normal. Analogous localized defects were detectable by immunolabeling with antilamin A/C and B2 antibodies, as well as by selective propidium iodide chromatin staining. The lesions we describe could be the result of anomalous nuclear lamina organization in the absence of emerin.

Cell Nucleus↗
PubMed1999

Experimental colitis increases small intestine permeability in the rat.

Small intestine permeability is frequently altered in patients with Crohn's disease and is thought to play a pathogenic role. The aim of this study was to investigate the permeability and structure of small intestine tight junctions (TJ) in an animal model of chronic distal colitis. Seven days after colitis induction with trinitrobenzenesulfonic acid/ethanol, the duodenal and ileal TJ were studied by means of transmission electron microscopy using lanthanum nitrate, freeze fractures, and immunohistochemistry of occludin, ZO-1, and cingulin. Animals treated with intrarectal ethanol alone served as controls. In controls, 7.5% of duodenal and 9.6% of ileal TJ were permeable to lanthanum, whereas in colitis, permeability increased significantly (79.5% and 72.9%, respectively; p < 0.001, both segments compared with controls). In colitis, the percentage of "leaky" junctions in duodena as well as in terminal ilea correlated positively with the macroscopic colon damage score (p < 0.02 and p < 0.005, respectively). Freeze-fracture analysis and immunohistochemistry of cingulin and ZO-1 did not reveal any difference between control and treated animals, whereas the signal of the transmembrane protein occludin was found to be disrupted and irregular in both small intestine segments. Distal colitis induces an increase of TJ permeability throughout the entire small intestine, and the extent of alterations correlates with colonic damage. Alterations in the transmembrane protein occludin seem to be responsible for the observed changes. Further investigation is needed to elucidate the mechanism of TJ alterations by a remote focus of inflammation.

Animals↗
PubMed1998

Increase of neuronal nitric oxide synthase in rat skeletal muscle during ageing.

Nitric oxide synthases (NOS) are different widely expressed enzymes which produce the molecular messenger nitric oxide. The neuronal isoform of NOS (nNOS) is involved in several processes of the cell metabolism, most of which are, at present, not fully understood (neurotransmission, smooth muscle motility, myoblast and myocyte biology and others). In skeletal muscle nNOS is present mainly at the plasmalemma, where it is attached to the dystrophin-related proteins; in fact, in pathologies involving dystrophin, nNOS is altered as well. We report that in aged rats the nNOS amount in skeletal muscle increases both in the soluble and microsomal fractions and that an additional intracytoplasmic localisation appears.

Aging↗
PubMed1998

Oral exfoliative cytology for the non-invasive diagnosis in X-linked Emery-Dreifuss muscular dystrophy patients and carriers.

Emery-Dreifuss muscular dystrophy (EMD) is an inherited myopathy characterised by muscle contractures, progressive muscle wasting and weakness, with humeroperoneal distribution. Cardiac arrhythmia and heart conduction block are also important characteristics of this disease. The X-linked form of EMD is caused by the absence of emerin, encoded by the STA gene (Xq28). Emerin is normally localized in muscle and other tissues at the nuclear rim. Currently, muscle and skin biopsies are used for the immunohistochemical diagnosis. We demonstrate that emerin is present in the cheek oral mucosa, in the exfoliating epithelial cells, and we propose the collection of these cells as a new method for the diagnosis of X-linked EMD patients and the detection of carriers by immunofluorescence techniques: smears from healthy subjects contained about 98% emerin-positive cells, those from X-linked EMD patients contained none and those from carriers contained about 45%. The technique is completely non-invasive, simple, repeatable and inexpensive.

Adolescent↗
PubMed1998

Immunocytochemical detection of emerin within the nuclear matrix.

Emerin, the protein whose production is altered in the X-linked form of Emery-Dreifuss muscular distrophy, has been hypothesized to be associated with the nuclear matrix on the basis of biochemical studies. In addition, immunocytochemical data reported its localization at the nuclear periphery, on the nuclear lamina, in sections of several normal tissues. We investigated the association of emerin with the nuclear matrix, by using cultured cells (SaOS-2, MG63 and HeLa-S3) and their in situ extracted matrix as a model, and immunocytochemical methods, both at the light and electron microscope level. Our results show a normal presence of emerin in the cultured cells and the specific persistence of emerin on the lamina of the in situ extracted nuclear matrix. This suggests a tight binding between emerin and the nuclear lamina independently from the interactions between the C-terminal hydrophobic domain of the protein and the inner nuclear membrane.

Cell Nucleus↗
PubMed1997

Serum laminin and type III procollagen in chronic hepatitis C. Diagnostic value in the assessment of disease activity and fibrosis.

Laminin P1 (pepsin-resistant fragment of laminin) and aminoterminal peptide of type III procollagen are measurable in serum and are now considered useful serum markers of fibrogenesis and inflammation in chronic liver diseases. However, very few studies thus far have focused on assessing the diagnostic value of these markers in detecting fibrosis and necro-inflammatory activity in chronically diseased liver. The aim of the present study was therefore to investigate the correlations of laminin and type III procollagen with liver histology and to compare their diagnostic value in detecting the degree of liver fibrosis and necro-inflammatory activity in a homogeneous group of 99 patients suffering from chronic hepatitis C, and lacking other factors which can directly affect the serum levels of the two markers. Both these serum markers were measured by radioimmunoassay, employing commercially available kits. The three main aspects of liver pathology, i.e. portal-periportal activity, lobular activity and fibrosis, were histologically evaluated and semiquantitatively expressed by numerical scores. The results of this study show that laminin and type III procollagen were both positively correlated with the histological scores for portal-periportal activity and with those for fibrosis, whereas no significant correlation was observed between each of the two serum markers and the histological scores for lobular activity. The sensitivity and specificity of laminin and type III procollagen in detecting histological aspects of fibrosis and disease activity in liver, computed at various cut-off levels, showed overlapping trends for the two markers; however, the diagnostic value was in general rather low, whatever the cut-off considered. We therefore conclude that the 'static' measurement of both serum laminin and type III procollagen is of limited value for individual diagnosis of liver damage.

Adolescent↗
PubMed1997

Fretting wear in a modular neck hip prosthesis.

In vitro cyclic load fretting tests were conducted on a prototype of a cementless, modular neck, hip prosthesis. The study had three major objectives: to determine the amount of fretted material in the tapered-neck joint under various load cycle amplitudes, to determine the fretting damage evolution, and to determine the effect of different-sized stem bodies on the production of debris. All the tests produced some fretting microdamage on the tapered surface although the extent was quite different among test groups. The amount of abraded material increased almost linearly with the applied load magnitude but not with the number of load cycles. The amount of weight loss was higher in the large stem bodies than in the small ones. Weight loss ranged from 0.28 +/- 0.10 mg for small stem bodies loaded 5.5 million times up to 2300N to 2.54 +/- 0.53 mg for large stem bodies located 20 million times up to 3300N. Considering the large-size stem results, and assuming one million load cycles between 300N and 3300N to be the average yearly load history, the modular neck tapered joint would produce 0.6 mg/year of metal debris. The clinical impact of this observation is unknown; however, some of the literature on the presence of metal in patient tissues and fluids supports the hypothesis that a normal and stable prosthesis is likely to produce less than 10 mg/year of metal debris. Thus, a further production of 0.6 mg/year due to the modular neck should not have any significant effect.

Alloys↗
PubMed1997

Intramembrane protein distribution in cell cultures is affected by 50 Hz pulsed magnetic fields.

Intramembrane proteins (IMP) represent a class of proteins located in the lipid bilayer of the cell membrane which function as ion channels, enzymes or receptors. Since it has been argued that biological effects of extremely low frequency (ELF) electromagnetic fields are mediated by plasma membrane. this work was designed to study the possible effects of 50 Hz pulsed magnetic fields (PMF) of the type used to stimulate bone repair, on the distribution of IMP in the plasma membrane of Swiss NIH 3T3 fibroblasts. Evaluations were based on the calculation of a distribution factor, which allows discrimination between random, regular and clustered distribution of IMP, in electron microscope images of freeze-fractured membranes. The results indicate that cells exposed to PMF for more than two hours have a significant clustering of the IMP distribution compared to control unexposed cells.

3T3 Cells↗
PubMed1997

Localization of the laminin alpha 2 chain in normal human skeletal muscle and peripheral nerve: an ultrastructural immunolabeling study.

A particular form of congenital muscular dystrophy is associated with a deficiency of the tissue-specific basement membrane protein laminin alpha 2. A more precise knowledge of the normal distribution and localization of laminin alpha 2 would be useful in further elucidating the development of this disorder. In this study we used specific electron microscopic techniques, i.e., thin-section fracture labeling and cryoultramicrotomy in combination with immunogold labeling for laminin alpha 2, to determine its ultrastructural localization in normal human muscle and peripheral nerve. Both in muscle and in peripheral nerve, laminin alpha 2 is found to be associated solely with the basal lamina of myofibers and Schwann cells, respectively. Of special interest is the finding that in peripheral nerve, laminin alpha 2 is associated only with myelinated and not with unmyelinated nerve fibers.

Humans↗
PubMed1997

Localization of laminin alpha 2 chain in normal human central nervous system: an immunofluorescence and ultrastructural study.

Recently, a rare form of congenital muscular dystrophy has been shown to be associated with a deficiency of laminin alpha 2 chain, a tissue-specific component of the basal lamina. Besides muscular dystrophy, children affected with this disorder also show electrophysiological and magnetic resonance imaging evidence of white matter involvement in the central nervous system (CNS). We have studied the precise localization of laminin alpha 2 chain in normal human brain, using specific electron microscopic techniques including thin-section fracture labeling and cryoultramicrotomy, in parallel with immunohistochemical techniques. We found that this laminin chain was localized to the basal lamina of all cerebral blood vessels, whereas blood vessels of the choroid plexus did not show any reaction. No positive reaction was found in meningeal blood vessels either. We hypothesize that in normal brain, laminin alpha 2 may be important for the selective filtration capability of the blood-brain barrier. The lack of laminin alpha 2 in cerebral vessels of children with laminin alpha 2-deficient congenital muscular dystrophy may cause impaired selective filtration, leading to leakage of plasma components and damage to the CNS. Further studies should be performed on patients affected by congenital muscular dystrophy associated with laminin alpha 2 deficiency to test this hypothesis.

Adult↗
PubMed1997

Intracellular detection of laminin alpha 2 chain in skin by electron microscopy immunocytochemistry: comparison between normal and laminin alpha 2 chain deficient subjects.

The aim of this study is to localize the alpha 2 laminin chain in normal human skin. The methods used were immuno-gold cytochemistry on cryo-ultramicrotomy sections and thin-section-fracture-label, together with electron microscopy observation. Results were compared with light microscopy peroxidase immuno-staining. Both normal skin samples and skin biopsies from laminin alpha 2 chain deficient congenital muscular dystrophy affected patients were studied. The results show that, in normal skin, the laminin alpha 2 chain is spread throughout the cytoplasm of basal keratinocytes, while it appears associated with desmosomal tonofilaments in the spinous and granular epidermal layers; in skin samples from dystrophic patients the laminin alpha 2 chain was not detectable. These data suggest that the function of the laminin alpha 2 chain is different in the epidermis as compared to that in muscle and peripheral nerve, where it is localized in the basement membrane.

Humans↗
PubMed1997

Heart-specific localization of emerin: new insights into Emery-Dreifuss muscular dystrophy.

Emery-Dreifuss muscular dystrophy (EDMD) is an X-linked inherited disease characterized by early contracture of the elbows, Achilles tendons and post-cervical muscles, slow progressive muscle wasting and weakness and cardiomyopathy presenting with arrhythmia and atrial paralysis: heart block can eventually lead to sudden death. The EDMD geneencodes a novel ubiquitous protein, emerin, which decorates the nuclear rim of many cell types. Amino acid sequence homology and cellular localization suggested that emerin is a member of the nuclear lamina-associated protein family. These findings did not explain the role of emerin nor account for the skeletal muscle- and heart-specific clinical manifestations associated with the disorder. Now we report that emerin localizes to the inner nuclear membrane, via its hydrophobic C-terminal domain, but that in heart and cultured cardiomyocytes it is also associated with the intercalated discs. We propose a general role for emerin in membrane anchorage to the cytoskeleton. In the nuclear envelope emerin plays a ubiquitous and dispensable role in association of the nuclear membrane with the lamina. In heart its specific localization to desmosomes and fasciae adherentes could account for the characteristic conduction defects described in patients.

Arrhythmias, Cardiac↗
PubMed1996

Cryoglobulinemia in hepatitis C virus chronic active hepatitis: effects of interferon-alpha therapy.

We investigated the prevalence of mixed cryoglobulinemia (MC) in 100 cases of chronic hepatitis C virus (HCV) infection and the effect of a 6-month treatment with interferon-alpha (IFN-alpha). Cryoglobulins were detected on admission in 36 of 100 patients and appeared during observation in a further 18 cases. Cryocrit ranged from 0.5% to 20%. Patients with MC were older and had a higher incidence of cirrhosis than those without MC. Immunologic characterization of the cryoprecipitate showed the presence of type II in 84% of cases and type III in 16%. The patients received IFN-alpha (6 MU three times per week) for 6 months. Fifty-seven were responders (i.e., reached normal aminotransferase levels), 26 of these relapsed within 2 months after IFN withdrawal, and 30 did not relapse. After IFN-alpha treatment, cryoglobulinemia disappeared in 11 of the 21 evaluable responders, but in none of the 15 nonresponder patients (p < 0.003). The clearance of MC was associated in all cases with clearance of HCV RNA. The delayed appearance of cryoglobulinemia in responders seems to be associated with a higher probability of relapse.

Adjuvants, Immunologic↗
PubMed1996

Long-term variations of serum laminin and procollagen III peptide in chronic HCV hepatitis after alpha-interferon therapy.

Twenty-three out of 40 patients affected by chronic HCV hepatitis responded (i.e. aminotransferases returned to normal) after 6-month treatment with 6 MU tiw of recombinant alpha-interferon 2a (IFN); in 11 (Group 1), the remission was maintained for a mean observation time of 33.15 months (range 20-50) after withdrawal of therapy; 12 (Group 2) relapsing after IFN withdrawal, were treated again obtaining in 10 a second response. Seventeen did not respond (Group 3). Serum markers of connective tissue metabolism (laminin and aminoterminal peptide of type III procollagen -NPIIIP-) were assayed in all patients before treatment and every 6th month, to evaluate long-term effects of IFN therapy. In non-responders, NPIIIP after treatment was not different from baseline, while laminin significantly increased at 6 and 12 months; in responders, NPIIIP decreased significantly after therapy, maintaining values lower than baseline on long-term observation. Laminin decreased significantly six months after the end of therapy and remained lower than baseline in all sustained responders. In this group, the drop in laminin was progressive, whereas in Group 2, laminin showed only a slight decrease on long-term control. Our data show that these serum markers persistently decrease in sustained responders to IFN, while in relapsed cases, prolonged therapy is needed to obtain minor effects on laminin; on the contrary, in non-responders, NPIIIP remains unchanged and laminin significantly increases, suggesting a persistence of active fibrogenesis.

Antiviral Agents↗
PubMed1994

Preparation of chromosome spreads for electron (TEM, SEM, STEM), light and confocal microscopy.

In the past, ultrastructural studies on chromosome morphology have been carried out using light microscopy, scanning electron microscopy and transmission electron microscopy of whole mounted or sectioned samples. Until now, however, it has not been possible to use all of these techniques on the same specimen. In this paper we describe a specimen preparation method that allows one to study the same chromosomes by transmission, scanning-transmission and scanning electron microscopy, as well as by standard light microscopy and confocal microscopy. Chromosome plates are obtained on a carbon coated glass slide. The carbon film carrying the chromosomes is then transferred to electron microscopy grids, subjected to various treatments and observed. The results show a consistent morphological correspondence between the different methods. This method could be very useful and important because it makes possible a direct comparison between the various techniques used in chromosome studies such as banding, in situ hybridization, fluorescent probe localization, ultrastructural analysis, and colloidal gold cytochemical reactions.

Chromosomes, Human↗