Claudia Moscheni

Friction and lubrication of pleural tissues.

The frictional behaviour of rabbits visceral pleura sliding against parietal pleura was assessed in vitro while oscillating at physiological velocities and amplitudes under physiological normal forces. For sliding velocities up to 3 cm s(-1) and normal compressive loads up to 12 cm H2O, the average value of the coefficient of kinetic friction (mu) was constant at 0.019 +/- 0.002 (S.E.) with pleural liquid as lubricant. With Ringer-bicarbonate solution, mu was still constant, but significantly increased (Deltamu = 0.008 +/- 0.001; P < 0.001). Under these conditions, no damage of the sliding pleural surfaces was found on light and electron microscopy. Additional measurements, performed also on peritoneum, showed that changes in nominal contact area or strain of the mesothelia, temperature in the range 19-39 degrees C, and prolonged sliding did not affect mu. Gentle application of filter paper increased mu approximately 10-fold and irreversibly, suggesting alteration of the mesothelia. With packed the red blood cells (RBC) between the sliding mesothelia, mu increased appreciably but reversibly on removal of RBC suspension, whilst no ruptures of RBC occurred. In conclusion, the results indicate a low value of sliding friction in pleural tissues, partly related to the characteristics of the pleural liquid, and show that friction is independent of velocity, normal load, and nominal contact area, consistent with boundary lubrication.

Deficient nitric oxide signalling impairs skeletal muscle growth and performance: involvement of mitochondrial dysregulation

BackgroundNitric oxide (NO), generated in skeletal muscle mostly by the neuronal NO synthases (nNOSμ), has profound effects on both mitochondrial bioenergetics and muscle development and function. The importance of NO for muscle repair emerges from the observation that nNOS signalling is defective in many genetically diverse skeletal muscle diseases in which muscle repair is dysregulated. How the effects of NO/nNOSμ on mitochondria impact on muscle function, however, has not been investigated yet.MethodsIn this study we have examined the relationship between the NO system, mitochondrial structure/activity and skeletal muscle phenotype/growth/functions using a mouse model in which nNOSμ is absent. Also, NO-induced effects and the NO pathway were dissected in myogenic precursor cells.ResultsWe show that nNOSμ deficiency in mouse skeletal muscle leads to altered mitochondrial bioenergetics and network remodelling, and increased mitochondrial unfolded protein response (UPRmt) and autophagy. The absence of nNOSμ is also accompanied by an altered mitochondrial homeostasis in myogenic precursor cells with a decrease in the number of myonuclei per fibre and impaired muscle development at early stages of perinatal growth. No alterations were observed, however, in the overall resting muscle structure, apart from a reduced specific muscle mass and cross sectional areas of the myofibres. Investigating the molecular mechanisms we found that nNOSμ deficiency was associated with an inhibition of the Akt-mammalian target of rapamycin pathway. Concomitantly, the Akt-FoxO3-mitochondrial E3 ubiquitin protein ligase 1 (Mul-1) axis was also dysregulated. In particular, inhibition of nNOS/NO/cyclic guanosine monophosphate (cGMP)/cGMP-dependent-protein kinases induced the transcriptional activity of FoxO3 and increased Mul-1 expression. nNOSμ deficiency was also accompanied by functional changes in muscle with reduced muscle force, decreased resistance to fatigue and increased degeneration/damage post-exercise.ConclusionsOur results indicate that nNOSμ/NO is required to regulate key homeostatic mechanisms in skeletal muscle, namely mitochondrial bioenergetics and network remodelling, UPRmt and autophagy. These events are likely associated with nNOSμ-dependent impairments of muscle fibre growth resulting in a deficit of muscle performance.

Extracellular signal-regulated kinases 1 and 2 phosphorylated neurons in the tele- and diencephalon of rat after visceral pain stimulation: an immunocytochemical study

We aimed at verifying whether extracellular signal-regulated kinases (erks) 1 and 2 are activated, i.e. phosphorylated, in forebrain neurons after visceral pain stimulation (VPS). Ether and urethane anaesthetized rats received an intraperitoneal injection of acetic acid or were left untreated (ECT, UCT). After 2 h the animals were perfused. Paraffin embedded brain sections immunoreacted with an antibody selective for the phosphorylated erks. The light microscope analysis revealed only a few labelled neurons in ECT, while in UCT, positive cells were detected. In VPS rats (VPSR) positive cells were mainly distributed in regions, such as the hypothalamic anterior and thalamic paraventricular midline nuclei, amygdala, hippocampal and parahippocampal, insular and perirhinal cortex, involved in nociception and/or visceral activities. Our data suggest an association of erks activation with the emotional component of nociception; moreover, they show that erks activation is not suppressed by anaesthesia.

Nitric oxide drives embryonic myogenesis in chicken through the upregulation of myogenic differentiation factors.

The muscle-specific variant of neuronal nitric oxide (NO) synthase (NOS-I), is developmentally regulated in mouse suggesting a role of NO during myogenesis. In chick embryo, a good model of development, we found that the expression of NOS-I is up-regulated, but only in the early phase of development. Through a pharmacological intervention in ovo we found that NO signalling plays a relevant role during embryonic development. The inhibition of NOS-I decreased the growth of embryo, in particular of muscle tissue, while the restoring of physiological NO levels, via administration of a NO donor, reversed this effect. We found a selective action of NO, produced by NOS-I, on regulatory factors involved in myogenic differentiation in the early phase of chick embryo development: inhibition of NO generation leads to a decreased expression of the Myocyte enhancer factor 2a (Mef2a), Mef2c, Myogenin and Myosin, which was reversed by the administration of a NO donor. NO had no effects on Myf5 and MyoD, the myogenic regulatory factors necessary for myogenic determination. The action of NO on the myogenic regulatory factors was mediated via generation of cyclic GMP (cGMP) and activation of the cGMP-dependent protein kinase G (PKG). Finally we found in myoblasts in vitro that the activation of Mef2c was the key event mediating the NO-induced modulation of myogenesis. Our results identify NO produced by NOS-I as a key messenger in the early phase of embryonic development of chicken, acting as a critical determinant of myogenesis through its physiological cGMP/PKG pathway.

Inhibition of CCR7/CCL19 axis in lesional skin is a critical event for clinical remission induced by TNF blockade in patients with psoriasis.

Despite the evidence that tumor necrosis factor (TNF) inhibitors block TNF and the downstream inflammatory cascade, their primary mechanism of action in inhibiting the self-sustaining pathogenic cycle in psoriasis is not completely understood. This study has the aim to identify early critical events for the resolution of inflammation in skin lesions using anti-TNF therapy. We used a translational approach that correlates gene expression fold change in lesional skin with the Psoriasis Area and Severity Index score decrease induced by TNF blockade after 4 weeks of treatment. Data were validated by immunofluorescence microscopy on skin biopsy specimens. We found that the anti-TNF-modulated genes that mostly associated with the clinical amelioration were Ccr7, its ligand, Ccl19, and dendritic cell maturation genes. Decreased expression of T-cell activation genes and Vegf also associated with the clinical response. More important, the down-regulation of Ccr7 observed at 4 weeks significantly correlated with the clinical remission occurring at later time points. Immunofluorescence microscopy on skin biopsy specimens showed that reduction of CCR7(+) cells and chemokine ligand (CCL) 19 was paralleled by disaggregation of the dermal lymphoid-like tissue. These data show that an early critical event for the clinical remission of psoriasis in response to TNF inhibitors is the inhibition of the CCR7/CCL19 axis and support its role in psoriasis pathogenesis.

Immunocytochemical localization of extracellular signal-regulated kinases 1 and 2 phosphorylated neurons in the brainstem of rat following visceral noxious stimulation.

The aim of the present study was to determine the activation of the extracellular signal-regulated kinases (ERKs) 1 and 2 in brainstem neurons following noxious visceral stimulation. Ether and urethane anaesthetized rats received an intraperitoneal injection of acetic acid (ENS, UNS) or were left untreated (ECT, UCT). Paraffin embedded brain sections immunoreacted with an antibody specific for phosphorylated ERKs. In noxious stimulated rats ERKs activated neuron profiles in the periaqueductal gray matter, parabrachial, dorsal raphe, solitary tract nucleus, area postrema and superior colliculus suggest that ERKs activation takes place mainly in brainstem nuclei in which nociception and visceral activities interact. The comparison between ENS and UNS rats shows that the long acting anaesthetic urethane attenuates the number of the ERKs activated neurons compared to the short acting ether.

Effects of interleukin-1β on chondroblast viability and extracellular matrix changes in bovine articular cartilage explants

Osteoarthritis is a degenerative disease of joint cartilage, characterized by the progressive and permanent degeneration of cartilage due to an imbalance in normal extracellular matrix turnover. Interleukin-1 beta is a proinflammatory agent, which is present in an elevated amount in osteoarthritic cartilage, and is thought to play a decisive role in osteoarthritis. Interleukin-1 beta acts as an important mediator of extracellular matrix changes where its activity is regulated by glycosaminoglycan composition. The aim of this study was to investigate the extracellular matrix changes in bovine cartilage explants following interleukin-1 beta treatment by morphological, histochemical and biochemical methods. Interleukin-1 beta stimulated the release of matrix sulfated proteoglycans in the culture medium, and significantly inhibited sulfated proteoglycan synthesis. These events were associated to a strong stimulation of nitric oxide production. Interleukin-1 beta-treated cartilage showed evident collagen fibers around the chondrocytes, together with diminished glycosaminoglycan sulfate content in the extracellular matrix of the explants. Moreover, the ultrastructure and viability of cells did not change in treated cartilage. Our data show that interleukin-1 beta modifies the ECM turnover without toxic effect on chondrocytes.

Morphometric analysis of hepatocellular nodular lesions in HCV cirrhosis.

We generated a computerized morphometric model to evaluate and quantify the morphological features in large regenerative nodules (LRN), high-grade dysplastic nodules (HGDN) and hepatocellular carcinoma (HCC). Sixteen LRN, 10 HGDN and 16 HCC in HCV-cirrhotic livers were stained with H&E, smooth muscle actin, CD34, CD31 and reticulin to evaluate volume and surface fractions. On H&E stains, the most discriminatory features between LRN, HGDN and HCC were volume fraction and the number of hepatocyte nuclei in unit volume and hepatocyte nuclear/cytoplasmic ratio. On immunohistochemistry, volume fractions of capillarised sinusoids, capillary units and isolated arteries were significantly different among all groups and highest in HCC; surface fraction of reticulin was markedly decreased in HCC. Our morphometric model is an objective method for quantification of the morphological changes of the nodular lesions, and it could be applied to studies involving histological evaluation of the spectrum of nodular lesions arising in the cirrhotic liver.

Ukrain modulates glial fibrillary acidic protein, but not connexin 43 expression, and induces apoptosis in human cultured glioblastoma cells

Glioblastoma is a highly malignant tumor, characterized by an unfavorable prognosis even in response to multidisciplinary treatment strategies, owing to its high-invasive phenotype. Ukrain, a semisynthetic thiophosphoric acid derivative of the purified alkaloid chelidonine, has been used in the therapy of several solid tumors, but little is known about its effect on glioblastoma and, in general, about the molecular mechanisms responsible for its effects. In particular, we previously demonstrated that Ukrain modulates the expression of genes and proteins involved in tumor invasion, and here we investigate some unreported effects of Ukrain on human cultured glioblastoma cells. We used morphological and molecular biology methods to analyze the expression and the intracellular distribution pattern of glial fibrillary acidic protein, the expression of the gap junction protein connexin 43 and the apoptotic effect in human glioblastoma cells treated with 0.1, 1 and 10 μmol/l Ukrain for 72 h. After treatment with 10 μmol/l Ukrain, glial fibrillary acidic protein fluorescence increased and a higher number of cells displayed glial fibrillary acidic protein organized into a filamentous state. Western blot analysis of glial fibrillary acidic protein confirmed that Ukrain tended to upregulate the protein. Connexin 43 was not modulated by Ukrain both at the mRNA and at the protein level. Ukrain-induced apoptotic rate was 4.63, 10.9 and 28.9% after 0.1, 1 and 10 μmol/l Ukrain, respectively, likely mediated by cytochrome c release in the cytoplasm. Considered as a whole, these findings provide new information to complete the understanding of the mechanisms of Ukrain antitumor and chemopreventive effect, and support the possible potential of Ukrain for the therapy of brain tumors.

A morphometric model to minimize subjectivity in the histological assessment of hepatocellular carcinoma and its precursors in cirrhosis

Objective: To explore how morphometry can minimize subjectivity in the assessment of liver nodules in cirrhosis using a novel classification tool. Study design: Ten hepatocellular carcinoma (HCC), 6 large regenerative nodules (LRN), and 34 regenerative (cirrhotic) nodules (RN), obtained from cirrhotic explant livers, were analyzed using a Kontron‐Zeiss KS400 image analyzer. We generated a morphometric model based on the analysis of volume fractions occupied by hepatocyte nuclei/cytoplasm, sinusoidal endothelium and lumen, neoplastic acini, fibrosis, centrilobular veins, portal arteries, veins and bile ducts, individual lesional arteries (smooth muscle actin), and capillarized sinusoids (CD34), and on surface fraction occupied by reticulin, and number in unit volume and size distribution of hepatocyte nuclei, and mean hepatocyte nucleus diameter and volume. Results: Volume fraction of capillarized sinusoids and of individual lesional arteries were more prominent in HCC and LRNs, when compared with RN, whereas surface fraction of reticulin was markedly decreased in HCC. The morphometric values of these three features were integrated into our classification tool to construct a hybrid system, which reclassified the nodules in the same categories. Conclusion: Our novel hybrid classification tool may minimize subjectivity in the histological assessment of nodular lesions in cirrhosis. Microsc. Res. Tech., 2008.