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Biomedical subjects

L Magaudda

Publications and source records attributed to L Magaudda.

At least 19 recordsLinked to original sources
PubMed2006

Culture of human skeletal muscle myoblasts: timing appearance and localization of dystrophin-glycoprotein complex and vinculin-talin-integrin complex.

The dystrophin-glycoprotein complex together with the vinculin-talin-integrin complex plays an important role in muscle function; in fact the mutations of their elements lead to diverse forms of muscular dystrophies. The relationship between the elements of dystrophin-glycoprotein complex and vinculin-talin-integrin and the time course of their formation are still not known in detail. In order to better understand this relationship we studied their expression during development in normal human skeletal muscle culture. Using a standardized muscle cell culture procedure, this study was performed to analyze the timing, appearance and the localization of some proteins of the dystrophin-glycoprotein complex and vinculin-talin-integrin complex during cellular proliferation (myoblast) and differentiation (4, 7, 15 and 21 days). The indirect immunofluorescence technique was used and cells were examined using a Meta Zeiss LSM510 confocal laser scanning inverted microscope. We examined the progressive appearance of the following proteins: alpha, beta, gamma, delta-sarcoglycans, beta-dystroglycan, dystrophin, talin, vinculin and integrin isoform alpha7/beta1. Immunofluorescence of these proteins, in satellite cells entering myogenic differentiation, revealed different patterns of localization depending on the time of culture. We showed that nondifferentiated cultures of human myoblasts expressed a perinuclear distribution of all proteins tested. During myoblast differentiation into myotubes (4 days) immunofluorescence gradually increased and was located in the whole cytoplasm. Subsequently, at day 7, a strong and homogeneous cytoplasmic labelling of all proteins was seen. At 15 days the distribution of the proteins was on the membrane. At this time some myotubes displayed a significant degree of precostameric banding pattern. As fusion proceeded at 21 days, the cytodistribution progressively changed and appeared along fibrillar longitudinal structures, and myotubes showed a clear periodic distribution (costameres). In conclusion, in normal human muscle cultures DGC and vinculin-talin-integrin proteins are first localized in the perinuclear region, then they diffuse in the cytoplasm and finally form at the plasma membrane into typical rib-like structures that are sarcolemma-associated.

Adult↗
PubMed2003

Distribution and localization of vinculin-talin-integrin system and dystrophin-glycoprotein complex in human skeletal muscle. Immunohistochemical study using confocal laser scanning microscopy.

The vinculin-talin-integrin system and the dystrophin-glycoprotein complex (DGC) are two protein systems with structural and signaling functions, allowing interaction between muscle fibers and extracellular matrix. Although numerous studies have been conducted on these systems, their localization and distribution patterns along the nonjunctional sarcolemma are not clear. On this basis, we carried out an indirect immunofluorescence study on the vastus lateralis muscle of human adults not affected by neuromuscular diseases to better define these patterns. Our results showed that all tested proteins of the two systems have a costameric distribution; all tested proteins of the two systems colocalize with each other (about 90-95% of the cases); only alpha-sarcoglycan in a few cases (about 6%) does not colocalize with other proteins; in about 9-10% of the cases, dystrophin and beta-dystroglycan colocalize partially with other proteins; all tested proteins can be localized in different fibers, both in the region of the sarcolemma over I or A bands. The colocalization between the vinculin-talin-integrin and DGC systems may imply their functional interaction involving the structural aspect, by providing a stronger adhesion between sarcolemma and extracellular matrix in well-defined regions of the muscle fiber. Besides, their colocalization may suggest the existence of a mechanism of mutual modulation of the transmitted signals. This reciprocal control may determine, in different conditions, the prevalence of one system over another with a consequent transmission of different messages to the sarcolemma-associated cytoskeleton.

Dystrophin↗
PubMed2002

Changes in the distribution of laminin alpha1 chain in psoriatic skin: immunohistochemical study using confocal laser scanning microscopy.

BACKGROUND: Recent studies have demonstrated the presence in psoriatic skin of ultrastructural and molecular alterations in the basement membrane and an altered polarized distribution of the integrins. Previous studies have demonstrated the existence of some epithelial cell lines synthesizing only laminin beta and gamma chains that, in the absence of the laminin alpha chain, do not form a distinct basal lamina. OBJECTIVES: To investigate a possible reduction/absence of the laminin alpha 1 chain in keratinocytes in psoriatic skin and to correlate this with fibronectin distribution. METHODS: Using monoclonal antibodies against the laminin alpha1 chain or human plasma fibronectin and using confocal laser scanning microscopy, we evaluated the immunohistochemical expression of these two proteins in cutaneous biopsies from involved and uninvolved skin of the sacral region of 12 men with extensive chronic plaque psoriasis. Site-matched biopsies of normal skin from four men without psoriasis were used as controls. RESULTS: In normal skin antilaminin alpha 1 chain antibodies stained the dermal-epidermal junction in a regular and continuous manner. In involved and uninvolved psoriatic skin large regions of discontinuous immunostaining were observed, mainly at the apex of the dermal papillae; in the same regions, clusters of keratinocytes appeared markedly reactive and fibronectin was overexpressed in the papillary dermis under the interruptions of the basement membrane. CONCLUSIONS: The present study defines the location of the laminin alpha1 chain in involved and uninvolved psoriatic skin and suggests a possible role of the alteration of this chain, together with T-cell lymphokines and fibronectin, in the dysregulation of cell morphological processes.

Adolescent↗
PubMed2000

"Sporadic" dystrophic epidermolysis bullosa: a new dominant or mitis recessive mutation?

We describe a case of dystrophic epidermolysis bullosa which occurred in a young boy who presented thickened and dystrophic nails both in hands and feet, atrophic scars on the elbows and knees, some large bullae and milia on the hands and ankles. The parents were clinically unaffected and the family medical history was negative for blistering disease. The immunofluorescence for type VII collagen was positive, yet low in intensity and the number of anchoring fibrils was reduced, as revealed by transmission electron microscopy. The diagnosis of a "sporadic" case of dominant dystrophic epidermolysis bullosa was suggested, although a mitis case of recessive dystrophic epidermolysis bullosa cannot be excluded on the basis of clinical, immunofluorescent and ultrastructural examination. However recent studies, carried out in a series of seemingly sporadic cases, have pointed out the possibility of inheritance of two mutant alleles from unaffected parents. This implies that 'mild' recessive dystrophic epidermolysis bullosa is commoner than once thought. This information is important for genetic counselling and determination of recurrence risk in the present and future generations.

Adolescent↗
PubMed1998

Immunohistochemical study of epidermal nerve fibres in involved and uninvolved psoriatic skin using confocal laser scanning microscopy.

Psoriasis is a typical hyperproliferative epidermal disease whose aetiopathogenesis is still to be defined. One of the most likely hypotheses is that it has a neurogenic origin correlated with an altered release of some neuropeptides by sensitive cutaneous nerves via antidromic pathways. As there are conflicting reports about the existence of cutaneous nerve alterations in psoriasis, we carried out an immunolocalization study using the protein gene product 9.5 as a marker for neuronal structures observed by confocal laser scanning microscopy in order to determine the pattern of sensory nerves in psoriatic skin. The investigation was carried out on cutaneous biopsies taken from involved (mature and long-established lesions) and uninvolved skin of ten patients with extensive chronic plaque psoriasis. In uninvolved psoriatic skin a significant decrease in epidermal nerve fibres was found, a further decrease was observed in mature lesions and almost a complete lack of epidermal nerve fibres in long-established psoriatic lesions. The reduction in epidermal nerve fibres and the consequent loss of relationship between these nerve structures and the skin immunocompetent cells (antigen-presenting cells, Langerhans cells, keratinocytes) might be a factor of fundamental importance in the self-maintenance of the disease.

Adolescent↗
PubMed1997

Changes in the distribution of actin-associated proteins in psoriatic keratinocytes. Immunohistochemical study using confocal laser scanning microscopy.

Recent studies support the presence of adherens junctions at the dermal-epidermal interface in addition to hemidesmosomes. In this area the integrin/actin-containing cytoskeleton connection occurs by means of a complex of proteins called actin-associated proteins (talin, vinculin, alpha-actinin). As previous studies have demonstrated the presence in psoriatic lesions of marked alterations in both the basement membrane molecular composition and the polarized expression of integrins, we decided to determine whether alterations in the behaviour of the actin-associated proteins could be demonstrated. We thus undertook an immunolocalization study with monoclonal antibodies directed against talin, vinculin, and alpha-actinin in cutaneous biopsies taken from involved and uninvolved skin of 12 patients with extensive chronic plaque psoriasis. The findings showed an almost total lack of reaction against talin and vinculin in the basal layer and an increased positivity against the proteins in the suprabasal layers. Similar, though less marked, alterations were present in uninvolved psoriatic skin. These results, in agreement with those of previous studies, confirm serious alterations in the matrix protein/cytoskeleton connection system, and support the hypothesis that this condition may play a key role in the pathogenesis of the disease.

Actinin↗
PubMed1996

Behaviour of laminin 1 and type IV collagen in uninvolved psoriatic skin. Immunohistochemical study using confocal laser scanning microscopy.

Previous studies have demonstrated the presence in psoriatic lesions of ultrastructural and molecular alterations of the basement membrane and an altered polarized distribution of the integrins; this latter alteration has also been observed in uninvolved skin. The aim of the present study was to determine, by means of immunolocalization with monoclonal antibodies directed against laminin 1 and type IV collagen and using confocal scanning laser microscopy, whether there are also alterations of the main components of the basement membrane in uninvolved skin. The findings showed a discontinuous and fragmented staining of laminin 1 and a normal distribution of type IV collagen. Taking into account both these results and the results of studies on epithelial cell lines, the authors hypothesize the existence of a functional deficit in psoriatic keratinocytes affecting the synthesis of the alpha 1 subunit of laminin. This deficit would explain: (1) the incapacity to produce mature trimeric laminin; (2) the altered assembly into a distinct basal lamina; (3) the loss of keratinocyte adhesion to the basement membrane; (4) alterations in the polarized distribution of the integrins; and (5) the consequent total or partial block of the cell signals regulating the processes of cytomorphosis. Already present in uninvolved skin, and enhanced by various irritative stimuli, this situation could be decisive for the appearance of psoriatic lesions.

Adolescent↗
PubMed1996

[Morphological variations of the human gastric mucosa after omeprazole treatment: a scanning electron microscopic study].

Numerous studies have been performed on the effects of omeprazole, a powerful inhibitor of gastric acid secretion, on the various morphotypes of oxyntic mucosa, whilst scant attention has been paid to modifications induced by this drug on surface epithelial mucosa. The authors carried out a SEM study on bioptic fragments removed at gastric level from 15 patients receiving omeprazole treatment for duodenal ulcer and/or reflux esophagitis, but apparently free from lesions to the mucosa of the body of the stomach. Biopsies were performed before the start, after two months and after seven-ten months of treatment. The results of basal biopsies showed an hypersecretive trend in surface epithelial cells, with frequent dissolution of the apical plasmalemma and emptying of cell bodies. After two months of treatment the hypersecretive phenomena regressed, whereas the mucosa appeared hypertrophic and presented typical cell polymorphism in some areas. After seventeen months of treatment the mucosa showed normal characteristics, except in one case in which there was a trend towards atrophy. In conclusion, the authors attribute the hypertrophic-dysplastic modifications observed after medium-term treatment to hypergastrinemia, secondary to treatment, and suggest careful morphological control follow-up during the course of treatment so as to obtain an early diagnosis of a possible deviation towards intestinal metaplasia.

Adult↗
PubMed1995

Epidermolysis bullosa junctionalis associated with urinary bladder exstrophy: a case report.

We report the second infant of nonconsanguineous parents with epidermolysis bullosa junctionalis associated with urinary bladder exstrophy, epispadias, anteriorized anus, and bilateral inguinal hernias. The family history also included the death of a maternal cousin due to epidermolysis bullosa. Our diagnosis was based on electron microscopy and immunofluorescence evidence. This patient is reported because of the rarity of this constellation of findings.

Abnormalities, Multiple↗
PubMed1994

Psoriasis and cyclosporin: immunohistochemical aspects of the basement membrane.

We have demonstrated both in vivo and in vitro that Cyclosporin (CsA) treatment during psoriasis induced a regression of typical keratinocyte alterations and normalization of the basement membrane (BM). It is also known that the structure of BM implies cohesion between the networks formed by laminin and type IV collagen and that these components positively influence the cytomorphosis processes of keratinocytes. According to these results, we have evaluated, by immunohistochemical study, the behaviour of laminin and type IV collagen on psoriatic skin prior to the therapy and at the end of pharmacological treatment with CsA. This study was carried out on biopsies of involved skin taken from 12 patients with severe psoriasis and with PASI between 50 and 70. Our results can be summed up as follows: Untreated psoriasis: absence of laminin within BM; modest staining in basal keratinocytes; intense staining in suprabasal keratinocytes; discontinuous staining of Type IV collagen in the BM. After treatment: evident and continuous staining of laminin and Type IV collagen within the BM. The obtained results confirm the positive effect of immunomodulation determined by CsA in the regulation of the functional activity of cells implicated in BM component production. In conclusion, the authors discuss the pathogenesis of the disease.

Basement Membrane↗
PubMed1990

[Enamel mineralization in rats subjected to an excess fluoride diet: SEM study].

Aim of our present work is to investigate with the SEM the process of enamel mineralization in the lower incisors of albino rats submitted for 21 days (a single amelogenetic cycle) to an hyperfluoric diet (five folds more than the normal). Our observations were performed on specimens fractured 8, 12 and 16 mm from the cervical loop transversally along the major axis of the incisor. It was demonstrated that the three different phases of enamel maturation were slower, so that, when the incisor erupted, mineralization was not completed and localized areas of demineralization were present. The authors are of the opinion that all morphological changes are dependent on the effect of fluoride on ameloblasts, either during their secretory or modulatory phases. On the basis of our results attention is pointed on the possible lesions of the enamel dependent from an unwary fluoride administration, particularly when decidual teeth are still present.

Animals↗
PubMed1989

Scanning electron microscopy of histological relapse after gluten-challenge in coeliac disease.

The steps of the morphological relapse occurring during gluten-challenge in coeliac children were for the first time investigated by scanning electron microscopy and compared with the morphological changes observed in untreated and treated coeliac patients, in pathological and normal controls. Some peculiar morphological changes, not reported up to now, were observed in treated and relapsed coeliac patients. No relationship was found among the degrees of mucosal atrophy observed by SEM and the duration of the challenge performed by an uncontrolled ingestion of gluten.

Celiac Disease↗
PubMed1989

[Computerized reconstruction of the spatial organization of enamel rods].

Morphometric reliefs on the enamel of the lower incisor of albino rats in correspondence with the prism compaction area during the first third of the ameloblastic modulation phase have been carried out. The reliefs were done on the longitudinal and median fracture plane and on the transversal fracture plane 8 mm from the cervical ansa. Measurements of the diameters of the honeycomb pits were carried out during the deposition phase, following removal of the ameloblastic coat. The data obtained were fed into an Apple Macintosh 512K/800 computer to obtain the geometric reconstruction of an isolated prism, the relations between each portion of the prism and the respective pits and a graphic example of the architectural organization of the enamel. It was shown that each prism consists of three distinct portion, just as there are three types of honeycomb pit. The external orifice of each pit is complementary to the interdigitant portion of the Tomes process, so the study of the pits may be used to evaluate the spatial orientation of the rods and not the morphology of their section. Cross-over between rows of contiguous rods occurs throughout the thickness of the internal enamel layer. The enamel possesses a particularly suitable structure for the transformation of surface type tangential forces into stresses or prevalently compression type.

Amelogenesis↗
PubMed1979

Activation of satellite cells induced by chronic neostigmine administration in the rat.

Muscle fibrillation has been suggested as a possible trigger for activation of satellite cells, a well known phenomenon associated with denervation. In order to test such a hypothesis fibrillation has been induced in normally innervated muscles by chronic administration of neostigmine and the response of satellite cells has been observed with a scanning electron microscope. The results show that satellite cells protrude from the profile of the muscle fiber, become partially separated from the latter, and align in rows. Elongated structures and presumable new muscle fibers are observed after 14 days of treatment. It is concluded that the overactivity of muscle fibers which is induced during fibrillation causes activation and differentiation of satellite cells. This result is consistent with that of a previous experiment showing that satellite cells are activated during acute increase in workload.

Animals↗
PubMedDate not supplied

The dermoepidermal junction in psoriatic skin as revealed by scanning electron microscopy.

Our previous ultrastructural and immunohistochemical studies, in vivo and in vitro, have shown important modifications of the basement membrane of psoriatic skin, which could play a key role in the alterations of keratinocyte adhesion, migration, proliferation and differentiation. In order to complete the morphological examination of all the structures in the dermoepidermal junction of psoriatic skin, we carried out a scanning electron microscopic study using biopsies taken from eight psoriatic patients. The biopsies were fixed in a mixture of 0.2% paraformaldehyde and 0.25% glutaraldehyde in 0.1 M cacodylate buffer at pH 7.4. The specimens were then frozen in liquid nitrogen and fractured following the natural cleavage planes and observed under a Jeol JSM-6301F field emission scanning electron microscope operating at 1.8-2.0 kV. The basal keratinocytes observed showed pore-like depressions on the lateral plasmalemma and villous-like projections in very dilated intercellular spaces. Moreover the basal cell plasma membrane was seen to rest on the papillary dermis without interposition of the lamina densa. The detachment of some keratinocytes enabled the examination of the lamina densa, which appeared slightly granular with numerous focal interruptions through which it was possible to observe the underlying collagen fibres. These findings, together with previously reported findings, support the hypothesis that in psoriasis molecular and structural alterations of the dermoepidermal junction are present, that could fundamentally alter the regulation of the cytomorphological processes and the normal functions of the basement membrane.

Adolescent↗
PubMedDate not supplied

[Use of synthetic resin cases for the scanning electron microscopic study of the kidney tubule system].

Aim of our present work was to investigate a new method to study the three-dimensional arrangement, the length and the diameter of the different parts of the renal tubules. The ureter was cannulated after blocking the urinary flow with a binding of the ureter itself at its intermediate third, and injected in it against flow a synthetic resin (Mercox) normally used for vascular corrosion casts. It was demonstrated that the binding maintained only for 24 hours is adequate for morphological studies of the urinary tracts from papillar ducts until the Henle's loop. On the contrary the binding maintained for 7 days induced marked changes in the tubular architecture similar to the first anatomo-pathological changes of the nephrosclerosis following a chronic obstructive nephropathy.

Animals↗