Basi ultrastrutturali della contrazione miocardica: la distensibilitá passiva del sarcomero quäle espressione della funzione ventricolare

Riassunto Dopo la discussione del metodo per la fissazione in toto del ventricolo sinistro a differenti pressioni passive di riempimento vengono riportati i dati biometrici ultrastrutturali della componente contrattile, dei mitocondri e del sistema trasversale del reticolo delle cellule miocardiche.L'aumento della pressione intraventricolare determina un rapido allungamento del sarcomero che raggiunge il valore di 2,2 a 10 mm Hg mentre il suo incremento è proporzionalmente minore ad elevate pressioni passive.Le miocellule degli strati sottoendocardici allo stesso livello pressorio sono inoltre maggiormente distese rispetto a quelle degli altri strati. Dall'analisi dei grafici relativi alle curve tensione/lunghezza e tensione/volume, risulta, inoltre, che l'allungamento dei sarcomeri è solo parzialmente responsabile dell'aumento della capacità ventricolare, per cui si può supporre che avvenga un nuovo ordinamento spaziale dei vari fasci nel contesto della parete.La distensibilitá passiva del sarcomero, qualora sia rapportata a precisi dati anatomo funzionali della cavità ventricolare, può essere ritenuta un valido modello per lo studio della contrattilità miocardica in condizioni normali e patologiche.

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Ultrastructural bases of myocardial contractility: the passive distensibility of the sarcomere, as an index of ventricular function

Summary Having described a method of total fixation of the left ventricle at different levels of passive pressure, the Authors refer about biometrical and ultrastructural data of the contractile component, the mitochondria and the transversal reticular system of the heart muscle cells.The raise of pressure in the ventricle determines a rapid increase of the sarcomere length, which can reach the value of 2,2 at a pressure of 10 mmHg. However, with higher passive pressures, a proportional minor increase of the sarcomere is found.With the same pressure, the myocells situated directly under the endocardium, became more distended than the myocells situated further in the myocard.From the analysis of the diagrams tension/length and tension/volume follows that the increase of the sarcomere is only partially responsible for the augmentation of the ventricular capacity. It is therefore possible that at the same time a new spatial arrangement of the fibres occurs.The passive distensibility, studied under any functional and anatomical condition of the ventricle, may be considered a valuable in vitro model for the study of the myocardial contractility under physiological as well as pathological conditions.

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La ricerca è stata eseguita con i fondi del C.N. R.     

Antioxidant activity of galloyl quinic derivatives isolated from P. lentiscus leaves

The antioxidant properties of galloyl quinic derivatives isolated from Pistacia lentiscus L. leaves have been investigated by means of Electron Paramagnetic Resonance spectroscopy (EPR) and UV-Vis spectrophotometry. Antioxidant properties have been also estimated using the biologically relevant LDL test. The scavenger activities of gallic acid, 5- O -galloyl, 3,5- O -digalloyl, 3,4,5- O -trigalloyl quinic acid derivatives, have been estimated against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, superoxide ( O 2 - ) radical, and hydroxyl (OH) radical. On the whole, the scavenger activity raised as the number of galloyl groups on the quinic acid skeleton increased. The half-inhibition concentrations (IC 50 ) of di- and tri-galloyl derivatives did not exceed 30 μM for all the tested free radicals. All the tested metabolites strongly reduced the oxidation of low-density lipoproteins (LDL), following a trend similar to that observed for the scavenger ability against OH radical.     

Age-related changes in endothelial nitric oxide synthase phosphorylation and nitric oxide dependent vasodilation: evidence for a novel mechanism involving sphingomyelinase and ceramide-activated phosphatase 2A

Aging is the single most important risk factor for cardiovascular diseases (CVD), which are the leading cause of morbidity and mortality in the elderly. The underlying etiologies that elevate CVD risk are unknown, but increased vessel rigidity appears to be a major hallmark of cardiovascular aging. We hypothesized that post-translational signaling pathways become disrupted with age and adversely affect endothelial nitric oxide synthase (eNOS) activity and endothelial-derived nitric oxide (NO) production. Using arterial vessels and isolated endothelia from old (33-month) vs. young (3-month) F344XBrN rats, we show a loss of vasomotor function with age that is attributable to a decline in eNOS activity and NO bioavailability. An altered eNOS phosphorylation pattern consistent with its inactivation was observed: phosphorylation at the inhibitory threonine 494 site increased while phosphorylation at the activating serine 1176 site declined by 50%. Loss of phosphorylation on serine 1176 was related to higher ceramide-activated protein phosphatase 2 A activity, which was driven by a 125% increase in ceramide in aged endothelia. Elevated ceramide levels were attributable to chronic activation of neutral sphingomyelinases without a concomitant increase in ceramidase activity. This imbalance may stem from an observed 33% decline in endothelial glutathione (GSH) levels, a loss known to differentially induce neutral sphingomyelinases. Pretreating aged vessel rings with the neutral sphingomyelinase inhibitor, GW4869, significantly reversed the age-dependent loss of vasomotor function. Taken together, these results suggest a novel mechanism that at least partly explains the persistent loss of eNOS activity and endothelial-derived NO availability in aging conduit arteries.     

Antioxidant properties of mesenchymal stem cells against oxidative stress in a murine model of colitis

Objective

To investigate the effects of oxidative stress injury in dextran sulfate sodium (DSS)-induced colitis in mice treated with mesenchymal stem cells (MSC).

Results

Mice exposed to oral administration of 2% DSS over 7 days presented a high disease activity index and an intense colonic inflammation. Systemic infusion of MSC protected from severe colitis, reducing weight loss and diarrhea while lowering the infiltration of inflammatory cells. Moreover, toxic colitis injury increased oxidative stress. Administration of DSS decreased reduced glutathione (GSH) and superoxide dismutase (SOD) activity, and increased thiobarbituric acid-reactive substances levels in the colon. No alteration was found in catalase (CAT) and glutathione peroxidase (GPx) activity. Otherwise, MSC transplantation was able to prevent the decrease of GSH levels and SOD activity suggestive of an antioxidant property of MSC.

Conclusion

The oxidative stress is a pathomechanism underlying the pathophysiology of colitis and MSC play an important role in preventing the impairment of antioxidants defenses in inflamed colon.

     

Consumption of Distinct Dietary Lipids during Early Pregnancy Differentially Modulates the Expression of microRNAs in Mothers and Offspring

Diet during pregnancy and lactation influences the offspring’s health in the long-term. Indeed, human epidemiological studies and animal experiments suggest that different type of fatty acids consumption during pregnancy affect offspring development and susceptibility to metabolic disorders. Epigenetic changes are thought to be elicited by dietary factors during critical timing of development. microRNAs (miRNAs) are versatile regulators of gene expression. Thus, we aimed to determine the influence of different fatty acids on miRNA expression in offspring when given during early pregnancy. We fed pregnant either soybean (SO), olive (OO), fish (FO), linseed (LO), or palm-oil (PO) diets from conception to day 12 of gestation; and standard diet thereafter. miRNA expression was assessed in liver an adipose tissue of pregnant rats and their virgin counterparts. While liver concentrations of fatty acids in pregnant or virgin rats replicated those of the diets consumed during early pregnancy, their pups’ liver tissue marginally reflected those of the respective experimental feeds. By contrast, the liver fatty acid profile of adult offsprings was similar, regardless of the diet fed during gestation. Different parental miRNAs were modulated by the different type of fatty acid: in adult offspring, miR-215, miR-10b, miR-26, miR-377-3p, miR-21, and miR-192 among others, were differentially modulated by the different fatty acids fed during early pregnancy. Overall, our results show that maternal consumption of different types of fatty acids during early pregnancy influences miRNA expression in both maternal and offspring tissues, which may epigenetically explain the long-term phenotypic changes of the offspring.     

Daily electroconvulsive shock treatment alters the inositol lipid system response in the rat hippocampus

The inositol lipid system (polyphosphoinositides and inositol phosphates) represents an important component of the cell signal transduction. Electroconvulsive shock (ECS) is known to activate cell signaling and lead to the release of second messengers. We tested the effects of daily ECS on the inositol lipid system and the generation of second messengers in vivo, by prelabeling the components of the system with [³H]myo inositol. The response to ECS was greater 30 sec after the sixth ECS, as compared to that obtained 30 sec after the first one. Also, rats killed 24h after the fifth ECS exhibited an increased PI labeling, as compared to rats handled for 6 days without receiving ECS. These results show that daily seizures (ECS-evoked) deeply modify the neuronal response to the stimulus, thus providing new information on the biochemical events involved in cell signal transduction during seizures.     

Synthesis of long-chain polyunsaturated fatty acids is inhibited in vivo in hypercholesterolemic rabbits and in vitro by oxysterols

Plasma total lipids, total cholesterol (cholesterol esters and free cholesterol) and oxysterol (mainly 7 beta-hydroxycholesterol (7 beta OH)) concentrations were significantly elevated in New Zealand rabbits fed a 2% cholesterol-containing diet with respect to controls fed the same diet without cholesterol. In addition, linoleic (18:2 n-6) and alpha-linolenic acid (18:3 n-3) plasma concentrations were significantly elevated in hypercholesterolemic rabbits, while concentrations of long-chain n-6 and n-3 derivatives were reduced. Studies in monocytic cell line THP-1 revealed that 7 beta OH markedly inhibited the conversion of 18:2 to 20:4 n-6 and of 18:3 to 22:6 n-3, indicating depression of the desaturation steps; in particular the inhibition was greater for the Delta 5 desaturation step. Furthermore, experiments of Real-Time PCR showed that 5-10 microM 7 beta OH decreased the Delta 5 gene expression. In conclusion, atherogenic oxysterols interfere with the production of long-chain polyunsaturated fatty acids from their precursors both in hypercholesterolemic rabbits and in cultured cells.     

Olive oils rich in natural catecholic phenols decrease isoprostane excretion in humans

This study was undertaken to evaluate, in humans, the antioxidant activity of olive oil phenolics, namely hydroxytyrosol and oleuropein aglycone that share an orthodiphenolic (catecholic) structure. Human volunteers were administered olive oil samples containing increasing amounts of an olive oil phenolic extract that was characterized by gas-chromatography/mass spectrometry. The administration of phenol-rich oils was dose-dependently associated with a decreased urinary excretion of 8-iso-PGF(2alpha), a biomarker of oxidative stress. Also, a statistically significant negative correlation between homovanillyl alcohol (HValc, hydroxytyrosol's major metabolite, formed through the COMT system) and F(2)-isoprostanes excretion was found. Thus, the administration of oil samples with increasing, albeit low, concentrations of orthodiphenolic compounds, namely hydroxytyrosol and oleuropein aglycone, results in a dose-dependent reduction in the urinary excretion of 8-iso-PGF(2alpha). The statistically significant negative correlation between 8-iso-PGF(2alpha) and HValc urinary concentrations suggests that this metabolite better reflects the in vivo activities of hydroxytyrosol.     

Exposure to alcohol or tobacco affects the pattern of maturation in oral mucosal cells: a cytohistological study

OBJECTIVE: To assess the maturation pattern of oral mucosal cells of patients exposed to tobacco and alcohol. METHODS: (i) Group without lesions. Smears obtained from the lower lip, border of the tongue and floor of the mouth of 31 control individuals (group I), 49 tobacco users (group II) and 27 tobacco/alcohol users (group III) were stained using the Papanicolaou method. The first 100 cells counted on each smear determined the maturation pattern and the keratinization index (KI). Analysis of variance (ANOVA) and the Tukey multiple comparison test were used for statistical analysis, at a 5% significance level. (ii) Group with lesions. Cytopathological and histopathological studies were conducted for 15 patients: eight with leucoplakia without epithelial dysplasia, two with epithelial dysplasia and five with squamous cell carcinoma. RESULTS: (i) Group without lesions. Statistical analysis revealed a smaller number of superficial cells with nuclei in all sites of the group of tobacco/alcohol users (group III) when compared to the control group (group I), and this difference was statistically significant (P<0.005). (ii) Group with lesions. The severity of histopathological findings increased with the increase in the number of cells of the deeper epithelial layers, with a statistically significant difference in the number of intermediate (P=0.013) and parabasal cells (P=0.049), which increased with the severity of the epithelial maturation disorder: leucoplakias with dysplasia had a greater number of intermediate and parabasal cells than leucoplakias without dysplasia; and the number in squamous cell carcinomas was greater than in leucoplakias with dysplasia. CONCLUSION: The maturation pattern of cells in the three anatomic sites showed changes that may be associated with the synergistic effect of tobacco and alcohol. Also, the severity of histopathological findings was associated with the increase in the number of cells in the deeper epithelial layers.