[The role of podocyte damage in the pathogenesis of glomerulosclerosis and possible repair mechanisms]. / Ruolo del danno podocitario nella patogenesi della glomerulosclerosi e possibili meccanismi di riparazione.

Converging evidence suggests that damage to podocytes plays a key role in progression towards glomerulosclerosis, in particular as the primary cause of all forms of focal segmental glomerulosclerosis (FSGS), the most common glomerular disease leading to end-stage renal disease. Any damage occurring to the complex architecture of specialized proteins that constitute the podocyte foot processes, essential to the highly specialized functions of podocytes, leads inevitably to loss of function in the glomerular filtration barrier, and ultimately to proteinuria. Recent studies have also highlighted that a reduction of the podocyte number in a damaged glomerulus is a critical factor for the development of proteinuria and glomerulosclerosis. As long as the podocyte loss is limited, restitution or repair is possible, which shows that the glomerular architecture can be remodeled. However, mature podocytes have limited capacity to divide and display all the phenotypic and functional features of highly specialized, terminally differentiated cells. A potential mechanism for podocyte replacement might be stem-cell-based regeneration, since it has been established that the developmental source of podocytes are resident renal progenitors. Podocyte damage could then be potentially repaired by a stem cell population resident in the kidney.

[The role of endothelial progenitor cells in renal disease]. / Ruolo dei progenitori endoteliali nelle malattie renali.

Recent evidence suggests that injury to the renal vasculature may play an important role in the pathogenesis of both chronic and acute ischemic kidney injury. Early alterations in peritubular capillary blood flow during reperfusion have been documented and associated with loss of normal endothelial cell function. In addition, ischemia induces alterations in endothelial cells that may promote inflammation and procoagulant activity, thus contributing to vascular congestion. Reduction of the microvasculature density increases hypoxia-mediated fibrosis and alters proper hemodynamics, which may lead to hypertension. This may play a critical role in the progression of chronic kidney disease following initial recovery from ischemia/reperfusion-induced acute kidney injury. The turnover and replacement of endothelial cells is therefore an important mechanism in the maintenance of vascular integrity also in the kidney. It is becoming clear that impaired vascular repair mechanisms as a result of a reduced number and/or impaired function of endothelial progenitor cells may contribute to renal disease. Moreover, investigators have begun to identify potential mechanisms responsible for the loss of function of endothelial progenitors in renal disease. In allografts, persistent injury results in excessive turnover of graft vascular endothelial cells. Moreover, chronic damage elicits a response that is associated with the recruitment of both leukocytes and endothelial progenitors, facilitating an overlapping process of inflammation and angiogenesis. In conclusion, angiogenesis and endothelial cell turnover play a pivotal role in renal disease and allograft rejection. Manipulation of these processes might have important implications for the development of novel therapeutic strategies in the near future.

Isocratic separations of closely-related mono- and disaccharides by high-performance anion-exchange chromatography with pulsed amperometric detection using dilute alkaline spiked with barium acetate.

Mixtures of closely related mono- and disaccharides may be efficiently separated by high-performance anion-exchange chromatography (HPAEC) only when relatively dilute alkaline eluents are employed (i.e., < 20 mM NaOH). The main drawbacks of these eluent solutions are (i) column regeneration between runs, (ii) poor reproducibility of the retention times, and (iii) the need for post-column base addition for enhancing sensitivity. Here, we describe some examples of isocratic separations of carbohydrates by HPAEC coupled with pulsed amperometric detection (PAD) accomplished by carbonate-free alkaline eluents (i.e., 5-20 mM NaOH) obtained upon addition of Ba(OAc)2 (1-2 mM). These separations include aldohexoses (i.e., galactose, glucose, and mannose), aminohexoses (i.e., glucosamine and galactosamine) and their N-acylated derivatives (i.e., N-acetylglucosamine and N-acetylgalactosamine) along with some isomeric disaccharides (i.e., lactose, lactulose and epilactose). The separation of closely related isomers of trehalose, alpha,alpha, alpha,beta, and beta,beta, is also presented. It is recommended to add Ba(OAc)2 to NaOH solutions several hours before using the alkaline eluent (i.e., 12-24 h) to ensure complete barium carbonate precipitation in the eluent reservoir. Adopting such a simple strategy can be especially useful for performing carbohydrate separations under isocratic conditions in which no regeneration and or re-equilibration of column between runs is required. Excellent repeatability of retention data throughout a three-day working session was observed, with relative standard deviations ranging from 2.0 to 3.7%, and from 0.5 to 2.0%, as day-to-day and within-day values, respectively. In addition, there was no need for postcolumn addition of strong bases to the eluent, and successful applications of the present approach confirmed its validity and practicability with detection limits of simple carbohydrates in the picomole range.

Neuroelectric procedure does not discriminate between painful and paresthetic diabetic neuropathy.

To investigate whether pain and paresthesias could identify two different subclasses of small-fibre diabetic neuropathy, and to evaluate their relation to the metabolic control, we tested nerve conduction velocity (NCV) of median nerve (sensitive-SM, and motor-MM) and deep peroneal nerve (DP) in 48 diabetics (24 IDDM, 24 NIDDM) reporting pain (group A) or paresthesias (group B) that might be due to diabetic polyneuropathy. Glycated haemoglobin (HbA1c) was also assessed. No difference between group A and group B was found either in NCV, in all nerves tested, or in HbA1c. No relation was observed between NCV of nerves tested and HbA1c, duration of diabetes, age and type of diabetes in both groups.

Novel strategies of regenerative medicine using chemical compounds.

Many diseases and/or physical defects due to injury result in the loss of specialized cells within organ systems and lead to organ system dysfunction. The ultimate goal of cell-based therapies is to regenerate and restore normal function. Populations of embryonic, fetal, adult stem cells and inducible pluripotent stem cells generated by reprogramming of adult cells show promise for the treatment of a variety of diseases. In addition, the recent advancements in adult stem cell biology in both normal and pathological conditions have led to the identification of some intrinsic and extrinsic factors that govern the decision between self renewal versus differentiation of tissue-resident adult stem cells. This is of primary importance for the design of an approach of stem cell-based therapy focused on their in vivo modulation by conventional chemical and biological therapeutics capable to stimulate endogenous cell regeneration. Such therapeutics can act in vivo to promote cell survival, proliferation, differentiation, reprogramming and homing of stem cells or can modulate their niches. In this review, we will highlight the burst of recent literature on novel perspectives of regenerative medicine and their possible clinical applications.

Method development for the quantitative determination of lactulose in heat-treated milks by HPAEC with pulsed amperometric detection.

A robust, rapid, and sensitive high-performance anion-exchange chromatographic method for the separation and quantitative determination of lactulose in heated milks, along with other common milk carbohydrates, has been developed. Complete separation of galactose, glucose, N-acetylgalactosamine, lactose, lactulose, and epilactose was isocratically accomplished in about 22 min by an anion-exchange column eluted with 10 mM NaOH spiked with 2 mM Ba(OAc)2. The within-day repeatability was lower than 2.1% for 10 repetitive injections. Under optimized conditions, there was no need either of post-column addition of strong bases to the eluent for enhancing detection sensitivity or, even more important, for column regeneration between chromatographic runs. Upon 100-fold sample dilution, the amperometric response of lactulose in milk samples was found to be linear up to 100 microM (r = 0.99935) with a limit of detection equal to 1.2 microM (S/N = 3). The lactulose content in ultrahigh-temperature (UHT) and sterilized milks was evaluated by a calibration graph using 2-deoxyglucose as the internal standard, making the proposed method very useful in discriminating among heat-treated milks. Whereas the mean value of lactulose in skimmed, partially skimmed, and whole UHT milks ranged from 10 to 90 mg/100 mL, lactulose content in bottle-sterilized whole milk (two samples) was higher than 140 mg/100 mL. The presence of epilactose, which is another isomer of lactose, was also ascertained in sterilized milk.