Early adhesion of human mesenchymal stem cells on TiO(2) surfaces studied by single-cell force spectroscopy measurements.

Understanding the interactions involved in the adhesion of living cells on surfaces is essential in the field of tissue engineering and biomaterials. In this study, we investigate the early adhesion of living human mesenchymal stem cells (hMSCs) on flat titanium dioxide (TiO(2) ) and on nanoporous crystallized TiO(2) surfaces with the use of atomic force microscopy-based single-cell force spectroscopy measurements. The choice of the substrate surfaces was motivated by the fact that implants widely used in orthopaedic and dental surgery are made in Ti and its alloys. Nanoporous TiO(2) surfaces were produced by anodization of Ti surfaces. In a typical force spectroscopy experiment, one living hMSC, immobilized onto a fibronectine-functionalized tipless lever is brought in contact with the surface of interest for 30 s before being detached while recording force-distance curves. Adhesion of hMSCs on nanoporous TiO(2) substrates having inner pore diameter of 45 nm was lower by approximately 25% than on TiO(2) flat surfaces. Force-distance curves exhibited also force steps that can be related to the pulling of membrane tethers from the cell membrane. The mean force step was equal to 35 pN for a given speed independently of the substrate surface probed. The number of tethers observed was substrate dependent. Our results suggest that the strength of the initial adhesion between hMSCs and flat or nanoporous TiO(2) surfaces is driven by the adsorption of proteins deposited from serum in the culture media.

Carboxymethylcellulose/single walled carbon nanotube complexes.

In this work, Carboxymethylcellulose/single walled carbon nanotube hybrids are prepared. Our goal is to use the non-covalent association of an anionic polysaccharide and single walled carbon nanotubes to prepare a biocompatible complex which preserves the intrinsic properties of the nanotubes. The hybrids are characterized by Raman scattering, Emission spectroscopy and Atomic Force Microscopy. A comparison is made with sodium dodecyl benzene sulfonate dispersed nanotubes. We show that carboxymethylcellulose forms an apparently non-helicoidal superstructure with carbon nanotubes which leads to their individualization. Emission and Raman spectroscopies suggest that the interaction occurs preferentially with semiconducting nanotubes. Further sugar chemistry may open different functionalization opportunities that will contribute to the design of biosensors and open this field of applications.

Study of the mechanical properties of myomesin proteins using dynamic force spectroscopy.

Myomesin is the most prominent structural component of the sarcomeric M-Band that is expressed in mammalian heart and skeletal muscles. Like titin, this protein is an intracellular member of the Ig-fibronectin superfamily, which has a flexible filamentous structure and which is largely composed of two types of domain that are similar to immunoglobulin (Ig)-like and fibronectin type III (FNIII) domains. Several myomesin isoforms have been identified, and their expression patterns are highly regulated both spatially and temporally. Particularly, alternative splicing in the central part of the molecule gives rise to an isoform, EH (embryonic heart)-myomesin, containing a serine and proline-rich insertion with no well-defined secondary structure, the EH segment. EH-myomesin represents the major myomesin isoform at embryonic stages of mammalian heart and is rapidly down-regulated around birth, but it is re-expressed in the heart of patients suffering from dilated cardio-myopathy. Here, in order to facilitate a better understanding of the physiological, and possibly pathological, functions of myomesin proteins, we explore the mechanical stability, elasticity and force-driven structural changes of human myomesin's sub-molecular segments using single-molecule force spectroscopy and protein engineering. We find that human myomesin molecules are composed of modules (Ig and FNIII), that are designed to withstand force and we demonstrate that the human cardiac EH segment functions like an additional elastic stretch in the middle part of the EH-myomesin and behaves like a random coil. Consequently myomesin isoforms (proteins with or without the EH segment) have different elastic properties, the EH-myomesin being the more compliant one. These findings imply that the compliance of the M-band increases with the amount of EH-myomesin it contains. So, we provide the evidence that not only titin but also other sarcomeric proteins have complicated visco-elastic properties depending on the contractile parameters in different muscle types.

[Effects of a low-fat diet including vegetables on total blood cholesterol levels in the aged]. / Effetti di una dieta ipolipidica integrata da legumi sui livelli di colesterolemia totale nell'anziano.

High total serum cholesterol and low HDL levels are major risk factors for cardiovascular disease before the age of 65. Currently in older populations their role has not yet been defined. In the elderly a low-cholesterol diet is therefore preferable to pharmacological treatment, in view of the absence of collateral effects. In this study 40 elderly patients with hypercholesterolemia were divided at random into two groups. They were respectively fed their usual diet and a legume-supplemented normal caloric diet for 8 weeks. Total serum cholesterol levels significantly decreased in the latter group from the 2nd week onward.

HbA1 levels in pregnancy: evaluation of a normal range and comparative study of impaired glucose tolerance.

The oral glucose tolerance test has been traditionally used to detect women with the gestational form of impaired glucose tolerance. We investigated whether the assessment of HbA1 levels could be a useful adjunct to these measurements. We found that HbA1 levels measured after the 35th week are not predictive of the percentile of each neonatal anthropometric parameter. Both metabolic and clinical maternal parameters as well as neonatal anthropometric parameters must also be evaluated.

A special, supplemented 'vegan' diet for nephrotic patients.

High dietary protein intake, in the past recommended for nephrotic syndrome, does not improve hypoproteinemia and may accelerate progressive renal damage. In contrast, low-protein diets reduce proteinuria and preserve renal function in experimental renal models of nephrotic syndrome. In this study, 20 steroid-resistant, nephrotic patients were treated with a pure vegetarian, low-protein diet, supplemented with essential amino acids and ketoanalogues (supplemented vegan diet, SVD) for 4.6 +/- 3.1 months. Before the study, these patients followed an unrestricted protein, low-sodium diet (LSD). Proteinuria, daily urea nitrogen excretion and creatinine clearance decreased significantly on SVD. A similar lowering effect of SVD was observed on serum total cholesterol. Seven of the 20 patients changed from LSD to SVD and vice-versa on 3 occasions, and in all cases, we found an increase of proteinuria during the LSD period. Serum albumin, HDL cholesterol, triglycerides and anthropometric measurements did not change on SVD. Our data suggest that SVD exerts a favorable effect on proteinuria and hypercholesterolemia in nephrotic patients, without inducing clinical or laboratory signs of malnutrition.

[Blood levels of maternal glycosylated hemoglobin (HbA1) in the 3d day of the puerperium and neonatal anthropometric parameters]. / Livelli ematici di emoglobina glicosilata (HbA1) materna in 3a giornata di puerperio e parametri antropometrici neonatali.

In the present study the Authors considered some neonatal anthropometric parameters such as head and chest circumference besides the neonatal weight and placental weight that may be more expressive of the fetal growth. All these parameters were correlated separately and jointly with maternal HbA1 levels of the third day of the post partum period. All mothers spent a pregnancy without any clinical and metabolic disorder. The data show a significant higher HbA1 mean value, than the controls, in mothers whose newborn showed one or more parameters like/superior the 90th centile. This finding may suggest that the evaluation of all the parameters together, the maternal HbA1 value can give more informations about the fetal growth.