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Biomedical subjects

Nadir Mario Maraldi

Publications and source records attributed to Nadir Mario Maraldi.

11 recordsLinked to original sources
PubMed2006

Ultrastructural defects of collagen VI filaments in an Ullrich syndrome patient with loss of the alpha3(VI) N10-N7 domains.

Ultrastructural alterations of collagen VI in cultured fibroblasts and reduced collagen VI immunostaining in the papillary dermis and endomysium were detected in a patient with a mild form of Ullrich congenital muscular dystrophy caused by a COL6A3 gene mutation. The patient had been previously demonstrated to express an alpha3(VI) chain shorter than normal due to skipping of the mutated exon. We show that collagen VI filaments are not organized in a normal network in the extracellular matrix secreted by patient's cultured fibroblasts. Moreover, we demonstrate that in this patient the alpha3(VI) chain is produced in lower amounts and it is almost exclusively represented by the shorter, alternatively spliced N6-C5 isoform. These results suggest that different alpha3(VI) chain isoforms, containing also domains of the N10-N7 region, are required for assembling a proper collagen VI network in the extracellular matrix.

Cells, Cultured↗
PubMed2006

Effects of antisense mediated inhibition of cathepsin K on human osteoclasts obtained from peripheral blood.

Cathepsin K is a cystein protease that displays a proteolytic activity against Type I collagen and is abundantly and selectively expressed in osteoclasts where it plays a critical role in bone degradation. Its direct role in bone tissue has been defined by knock-out mice studies and inhibiting strategies in animals models. However, direct proof of cathepsin K function in human osteoclast model in vitro is lacking. The aim of this study is to analyze cathepsin K expression and localization in human osteoclasts obtained from peripheral blood and to examine cathepsin K function in these cells by antisense oligodeoxynucleotide (AS-ODN) strategy. AS-ODN was added to the culture of osteoclast precursors induced to differentiate by RANKL and M-CSF. AS-ODN treatment produced a significant down-regulation of cathepsin K mRNA (>80%) and protein expression, as verified respectively by Real-time PCR and by immunocytochemistry or Western blot. The cathepsin K inhibition caused an impairment of resorption activity as evaluated by a pit formation assay ( p = 0.045) and by electron microscopy, while the acidification process was unaffected. We demonstrated that antisense strategies against cathepsin K are selectively effective to inhibit resorption activity in human osteoclasts, like in animal models.

Acids↗
PubMed2005

Quantitative immunodetection of key elements of polyphosphoinositide signal transduction in osteoblasts from arthritic patients shows a direct correlation with cell proliferation.

Phosphoinositides play an essential role in diverse cellular functions such as cell proliferation, cytoskeletal regulation, intracellular vesicle trafficking, motility, cell metabolism and death. Alteration of these pathways is common to many diseases. In this study, we show that osteoblasts from patients affected by osteoarthritis (OA) and by rheumatoid arthritis (RA) present a decreased cell proliferation and a reduced expression of the key elements of polyphosphoinositide signal transduction such as phosphatidylinositol-3-kinase (PI 3K), phospholipase C gamma1 (PLCgamma1), and protein kinase C zeta (PKCzeta) compared to the post-traumatic (PT) patients. Our results suggest that a correlation may exist between the reduced osteoblast proliferation observed in OA and RA patients and the lowered expression of PI 3K, PLCgamma1, and PKCzeta enzymes. The reduced proliferation rate of osteoblasts in response to these signal transduction effectors could counteract the evolution of arthritic disease.

Aged↗
PubMed2005

Cellular and molecular events during chondrogenesis of human mesenchymal stromal cells grown in a three-dimensional hyaluronan based scaffold.

Mesenchymal stromal cells (MSCs) seem to be a good alternative to chondrocytes for cartilage regeneration. To obtain new information on the sequence of cellular and molecular events during in vitro chondrogenic differentiation we analysed MSCs on a widely used hyaluronic acid biomaterial (Hyaff-11). Cellular differentiation was induced using two different concentrations of TGFbeta1 (10 and 20 ng/ml) and the process was analysed at different time points (24 h, and 7, 14, 21 and 28 days) using techniques of light and electron microscopy, real-time PCR and immunohistochemistry. We found that without TGFbeta MSCs did not survive while in the presence of TGFbeta the cells significantly proliferated from day 7 until day 28. Light and electron microscopy showed that TGFbeta at 20 ng/ml better induced the formation of cartilage-like tissue. Real-time PCR showed an increased expression of collagen type II, IX and aggrecan associated to a down-regulation of collagen type I. Immunohistochemical analysis confirmed that collagen type I was down-modulated while collagen type II increased from day 14 to day 28. These data clearly showed that higher concentrations of TGFbeta (20 ng/ml) induce chondrogenesis of MSCs on Hyaff-11 scaffold better than 10 ng/ml of TGFbeta. This process is characterized by a sequence of cellular and molecular events that deal with the in vitro formation of a cartilage-like tissue.

Biocompatible Materials↗
PubMed2004

Leiomyosarcoma of the spermatic cord: a light and ultrastructural description of one case.

A case of leiomyosarcoma arising in the spermatic cord is described. A 83-year-old man required medical care for an irreducible inguinal hernia. The patient underwent herniorraphy and transinguinal radical orchiectomy. Macroscopically, the spermatic cord was enlarged by a gray-tan and ill-defined neoplasm measuring 4 x 4 x 3 cm. Histologically, this proliferation was composed of atypical spindle cells with blunted end nuclei and eosinophilic cytoplasm. Immunohistochemistry and ultrastructure confirmed the smooth muscle nature of the neoplastic cells. The diagnosis of leiomyosarcoma of the spermatic cord was made. To improve the assignment of this rare lesion to its specific anatomic location, we analyzed the immunohistochemical and ultrastructural characteristics of the smooth muscle tumoral cells and in particular those of the intracellular filament aggregates.

Actins↗
PubMed2003

Interleukin-1-receptor-associated kinase 2 (IRAK2)-mediated interleukin-1-dependent nuclear factor kappaB transactivation in Saos2 cells requires the Akt/protein kinase B kinase.

The post-receptor pathway that leads to nuclear factor kappaB (NF-kappaB) activation begins with the assembly of a membrane-proximal complex among the interleukin 1 (IL-1) receptors and the adaptor molecules, myeloid differentiation protein 88 (MyD88), IL-1-receptor-associated kinases (IRAKs) and tumour-necrosis-factor-receptor-associated factor 6. Eventually, phosphorylation of the inhibitor of NF-kappaB (IkappaB) by the IkappaB kinases releases NF-kappaB, which translocates to the nucleus and modulates gene expression. In this paper, we report that IRAK2 and MyD88, but not IRAK1, interact physically with Akt, as demonstrated by co-immunoprecipitation and pull-down experiments. Interestingly, the association of Akt with recombinant IRAK2 is decreased by stimulation with IL-1, and is favoured by pre-treatment with phosphatase. Likewise, Akt association with IRAK2 is increased considerably by overexpression of PTEN (phosphatase and tensin homologue deleted on chromosome 10), while it is completely abrogated by overexpression of phosphoinositide-dependent protein kinase 1. These data indicate that Akt takes part in the formation of the signalling complex that conveys the signal from the IL-1 receptors to NF-kappaB, a step that is much more membrane-proximal than was reported previously. We also demonstrate that Akt activity is necessary for IL-1-dependent NF-kappaB transactivation, since a kinase-defective mutant of Akt impairs IRAK2- and MyD88-dependent, but not IRAK1-dependent, NF-kappaB activity, as monitored by a gene reporter assay. Accordingly, IRAK2 failed to trigger inducible nitric oxide synthase and IL-1beta production in cells expressing dominant-negative Akt. However, NF-kappaB binding to DNA was not affected by inhibition of Akt, indicating that Akt regulates NF-kappaB at a level distinct from the dissociation of p65 from IkappaBalpha and its translocation to the nucleus, possibly involving phosphorylation of the p65 transactivation domain.

Cell Line↗
PubMed2003

IL1-beta and TNF-alpha induce changes in the nuclear polyphosphoinositide signalling system in osteoblasts similar to that occurring in patients with rheumatoid arthritis: an immunochemical and immunocytochemical study.

Osteoarthritis (OA) and rheumatoid arthritis (RA) are common joint diseases that can lead to destruction of cartilage and structural changes in the subchondral bone. In this study we show by western blot and quantitative immunocytochemistry that nuclear phospholipase C beta(1) (PLC beta(1)) and phosphatidylinositol 4,5-bisphosphate (PIP(2)), two key elements of the polyphosphoinositide signal transduction system that regulate different cellular processes, increase in primary osteoblast cultures of RA patients when compared with post-traumatic after fall (PT) patients, whilst those of OA are not significantly affected. Moreover, we demonstrate that these alterations could be induced in PT osteoblasts by proinflammatory cytokines IL-1 beta and TNF-alpha. This suggests that proinflammatory cytokines, highly produced by RA infiltrating mononuclear cells, can modulate the nuclear polyphosphoinositide signalling pathway of the osteoblasts involved in bone remodelling.

Arthritis, Rheumatoid↗
PubMed2003

Association of emerin with nuclear and cytoplasmic actin is regulated in differentiating myoblasts.

Emerin is a nuclear envelope protein whose biological function remains to be elucidated. Mutations of emerin gene cause the Emery-Dreifuss muscular dystrophy, a neuromuscular disorder also linked to mutations of lamin A/C. In this paper, we analyze the interaction between emerin and actin in differentiating mouse myoblasts. We demonstrate that emerin and lamin A/C are bound to actin at the late stages of myotube differentiation and in mature muscle. The interaction involves both nuclear alpha and beta actins and cytoplasmic actin. A serine-threonine phosphatase activity markedly increases emerin-actin binding even in cycling myoblasts. This effect is also observed with purified nuclear fractions in pull-down assay. On the other hand, active protein phosphatase 1, a serine-threonine phosphatase known to associate with lamin A/C, inhibits emerin-actin interaction in myotube extracts. These data provide evidence of a modulation of emerin-actin interaction in muscle cells, possibly through differentiation-related stimuli.

Actins↗
PubMed2003

Involvement of nuclear phosphatidylinositol-dependent phospholipases C in cell cycle progression during rat liver regeneration.

Nuclear lipid metabolism is involved in the regulation of cell proliferation. Modulation of the expression and activity of nuclear PI-phospholipase C (PI-PLC) has been reported during liver regeneration after partial hepatectomy, although it has not been determined whether different PLC isoforms play specific roles in the regulation of cell cycle progression. Here, we report evidence that the increased activity of nuclear PLCs in regenerating rat liver occurs before the peak of DNA replication and involves the enzyme activity associated to the chromatin and not that associated to the nuclear membrane. Immunocytochemical analyses indicate that PI-PLC beta(1) isoform is exclusively localized at the chromatin level, PI-PLC beta(1) co-localizes with DNA replication sites much more than PI-PLC gamma(1), which is also present at the nuclear envelope. These findings and the increased amount of PI-PLC gamma(1) occurring after the peak of DNA replication suggest that PI-PLC beta(1) and gamma(1) play different roles in cell cycle progression during regenerating liver. The increased activity of PI-PLC beta(1) constitutively present within the hepatocyte nucleus, should trigger DNA replication, whereas PI-PLC gamma(1) should be involved in G2/M phase transition through lamin phosphorylation.

Animals↗
PubMed2002

Combined use of PRINS and FISH in the study of the dystrophin gene.

The efficacy of fluorescence in situ hybridization (FISH) may be limited in specific applications by low-resolution sensitivity. Primed in situ labeling (PRINS) is based on specific hybridization of an unlabeled oligonucleotide with a denatured template and synthesis of a single-strand DNA in situ. This method may represent a powerful alternative to FISH for gene mapping because of its ability to generate multiple independent signals within the same gene segment. We investigated the specificity of signals produced by a modified PRINS protocol combining a centromeric probe for the X-chromosome with specific primers for 3'- and 5'-terminal regions of the dystrophin gene. In approximately 70% of nuclei from male and female subjects, we detected one or two large signals (X-chromosome centromere) and two or four smaller signals (the two regions of the dystrophin gene). Specific hybridization of the oligonucleotides on Xp was demonstrated by localization of the smaller (dystrophin) and larger (X-centromere) signals on the same chromosome. Simultaneous hybridization with a centromeric probe and gene-specific oligonucleotides allowed localization of PRINS signals, and assessment of the specificity of the primers used for hybridization. This approach could facilitate identification of female carriers of small intragenic deletions in the dystrophin gene.

Base Sequence↗