YAP/TAZ mechano-transduction as the underlying mechanism of neuronal differentiation induced by reduced graphene oxide.

AIM: The aim of this work is the dissection of the molecular pathways underlying the differentiation effect of reduced graphene oxide (GO) materials in the absence of differentiation agents. MATERIALS & METHODS: Reduced GO is obtained either by drop casting method and heat-treated or biological reduction by the interaction between GO and wtPrxI. Cells were grown on both materials and the differentiation process studied by immunological and morphological detection. RESULTS & CONCLUSION: The results obtained indicate that both reduction methods of GO can determine the modulation of pathway involved in mechano-transduction and differentiation, by affecting YAP/TAZ localization outside the nuclei and increasing neuronal differentiation markers. This suggests that the mechano-transduction pathways are responsible for the differentiation process.

Switching between the alternative structures and functions of a 2-Cys peroxiredoxin, by site-directed mutagenesis.

Members of the typical 2-Cys peroxiredoxin (Prx) subfamily represent an intriguing example of protein moonlighting behavior since this enzyme shifts function: indeed, upon chemical stimuli, such as oxidative stress, Prx undergoes a switch from peroxidase to molecular chaperone, associated to a change in quaternary structure from dimers/decamers to higher-molecular-weight (HMW) species. In order to detail the structural mechanism of this switch at molecular level, we have designed and expressed mutants of peroxiredoxin I from Schistosoma mansoni (SmPrxI) with constitutive HMW assembly and molecular chaperone activity. By a combination of X-ray crystallography, transmission electron microscopy and functional experiments, we defined the structural events responsible for the moonlighting behavior of 2-Cys Prx and we demonstrated that acidification is coupled to local structural variations localized at the active site and a change in oligomerization to HMW forms, similar to those induced by oxidative stress. Moreover, we suggest that the binding site of the unfolded polypeptide is at least in part contributed by the hydrophobic surface exposed by the unfolding of the active site. We also find an inverse correlation between the extent of ring stacking and molecular chaperone activity that is explained assuming that the binding occurs at the extremities of the nanotube, and the longer the nanotube is, the lesser the ratio binding sites/molecular mass is.

Parathyroid hormone and large related C-terminal fragments increase at different rates with worsening of renal function in chronic kidney disease patients. A possible indicator of bone turnover status?

BACKGROUND: The intact parathyroid hormone (PTH) serum value has been the non-invasive biomarker of choice for the early diagnosis of renal bone disease in the chronic kidney disease (CKD) patient population. It has now been known that the intact PTH assay value is the sum of 1-84 PTH (true hypercalcemic PTH) and large C-terminal PTH fragments, mainly 7-84 PTH, a fragment with hypocalcemic hormone actions. AIM: The aim of this study was to investigate the differences among the different functional stages of CKD in the following PTH parameters: intact PTH, 1-84 PTH, 7-84 PTH, and the ratio 1-84 PTH/7-84 PTH. GFR (clearance of 99mTc-DTPA) was measured in 164 (85 males and 79 females) adult CKD patients with different degrees of renal function impairment (serum creatinine 0.50 12.1 mg/dl, mean 2.00). PATIENTS AND METHODS: Plasma concentrations of calcium, phosphate, 1-84 PTH and intact PTH were also measured. The value of 7-84 PTH was calculated as the difference between intact PTH and 1-84 PTH. The reduction of, GFR was accompanied by an increase of intact PTH, with a prevalent increase of 7-84 PTH over 1-84 PTH, resulting in a decrease of the ratio 1-84 PTH/7-84 PTH. RESULTS: The values of 7-84 PTH showed a discrimination between Stages 1 and 2 (GFR > 60 ml/min ) and Stage 3 (GFR 30 60 ml/ min) CKD patient populations. In fact, 7-84 PTH was already significantly increased in patients at CKD Stage 3. The analysis of individual patients indicated that a low value (< 1.4) of the ratio 1-84 PTH/7-84 PTH, suggestive for low bone turnover, was already found in more than 20% of CKD Stage 3 patients. CONCLUSION: The results of the present study demonstrate that the reduction in GFR is accompanied by a higher increase in 7-84 PTH with respect to 1-84 PTH, which suggests the possibility that bone metabolism and calcemic status are already reduced in patients with moderate renal failure (CKD Stage 3).

[Acid-base equilibrium in the critically ill]. / L'equilibrio acido-base nel paziente in area critica.

The reasons causing a patient to be hospitalized in the ICU, the degree of organs involvement and the subsequent therapeutic interventions, are all elements that can interfere with the acid-base homeostasis. It may be difficult to correctly evaluate the disturbances of the acid-base balance and to understand the underlying physiopathological process. Though, it is crucial to clarify the steps that resulted in the alteration, in order to increase the probability of detecting the correct diagnosis and therapy. Two other elements make the understanding more complex first, it is difficult to estimate, even approximately, the degree of involvement of the 'structural' buffer systems (intracellular buffers, proteins, activation or inhibition of metabolic pathways, etc.) to calculate the total acid load and then quantify the bases necessary to restore the patient balance. Then, the disorder severity is too often assessed through the arterial blood gas analysis parameters, which limits observation to a restricted vascular area, and the disorder assessment to the bicarbonate-carbonic acid system.

Renal effects of cardiac angiography with different low-osmolar contrast media.

The aim of this study was to evaluate the renal effects of cardiac angiography performed with three low-osmolar contrast media (CM): iopromide (IPR), ioversol (IVR) and ioxaglate (IOX). IPR and IVR are non-ionic CM, IOX is an ionic CM. Different parameters of renal function were determined before and 6, 24, 48, 72 hrs after angiography in 45 patients: 15 patients were examined with IPR, 15 with IVR and 15 with IOX. Glomerular effects--Plasma creatinine increased slightly at the 24th hour after IVR and IOX and at 48 hours after IOP. A significant increase in plasma beta2-microglobulin was observed, at the same time, only after IOX. A significant decrease in creatinine clearance was found at 6 hours after IOX. No significant variations in glomerular filtration rate (GFR) and in effective renal plasma flow were found at 48 hours after cardiac angiography; while filtration fraction was significantly reduced after IOP and IOX. Tubular effects--A marked decrease in sodium clearance and a relevant increase of urinary activities of different tubular enzymes were found after cardiac angiography with all CM, but were more evident after the ionic CM IOX, than after the two non-ionic agents. These tubular effects reached the maximum between 6 and 24 hours and returned to baseline within 72 hrs after cardiac angiography. In conclusion, slight glomerular effects were observed mainly after IOX. A reversible tubular malfunction was found with the three low-osmolar CM and was more evident after ionic CM IOX. thus suggesting that other mechanisms, besides osmolarity, play a role in tubular toxicity due to CM. In no patient did the glomerular and tubular effects of CM have a clinical relevance.

Cystatin C, beta 2-microglobulin, and retinol-binding protein as indicators of glomerular filtration rate: comparison with plasma creatinine.

BACKGROUND: The aim of this study was to assess the diagnostic accuracy of plasma levels of three low-molecular weight proteins cystatin C, beta 2-microglobulin, and retinol-binding protein, as indicators of impairment of glomerular filtration rate in comparison with plasma creatinine. METHODS: Glomerular filtration rate (GFR) was measured in 110 patients (51 M and 59 F, aged 18--79 years); creatinine (Creat), cystatin C (Cys), beta 2-microglobulin (beta 2M), and retinol-binding protein (RBP) were determined on the same day. The correlation coefficients between the different markers and GFR were determined. Receiver-operating characteristics (ROC) analysis was performed to assess their diagnostic accuracy. Furthermore, the relationship between plasma levels of the examined markers of GFR and body weight, height, fat-free mass (FFM) and body cell mass (BCM) was determined. FFM and BCM were calculated by means of total body electrical impedance measurement. RESULTS: Serum concentrations of Cys, beta 2M and RBP increase progressively with the reduction of GFR. The magnitude of the increase in blood levels of Creat and beta 2M was higher than the increase of Cys, and much more than that of RBP, in particular in patients with GFR<20 ml/min/1.73 m(2). The correlation coefficients between GFR and 1/plasma concentrations were 0.647 for Creat, 0.651 for Cys, 0.731 for beta 2M, and 0.406 for RBP. ROC analysis indicated that the accuracy of beta 2M and Cys, as indicators of different degrees of GFR impairment (<80, <60, and <40 ml/min per 1.73 m(2)), was similar to that of Creat, while the diagnostic accuracy of RBP resulted significantly lower than that of Creat for any level of GFR. In patients without renal failure (GFR>40 ml/min per 1.73 m(2)), plasma concentrations of Creat were positively correlated with body weight (P<0.01), height (P<0.01), FFM (P<0.001) and BCM (P<0.001). Serum concentrations of RBP resulted correlated with FFM (P<0.05) and BCM (P<0.05), while no correlation was found between anthropometric data and Cys and beta 2M. CONCLUSION: Cystatin C and beta 2-microglobulin have a diagnostic accuracy very similar to that of creatinine, while retinol-binding protein is not an adequate marker of glomerular filtration.