Structural Integrity of Nucleolin Is Required to Suppress TDP-43-Mediated Cytotoxicity in Yeast and Human Cell Models

The Transactivating response (TAR) element DNA-binding of 43 kDa (TDP-43) is mainly implicated in the regulation of gene expression, playing multiple roles in RNA metabolism. Pathologically, it is implicated in amyotrophic lateral sclerosis and in a class of neurodegenerative diseases broadly going under the name of frontotemporal lobar degeneration (FTLD). A common hallmark of most forms of such diseases is the presence of TDP-43 insoluble inclusions in the cell cytosol. The molecular mechanisms of TDP-43-related cell toxicity are still unclear, and the contribution to cell damage from either loss of normal TDP-43 function or acquired toxic properties of protein aggregates is yet to be established. Here, we investigate the effects on cell viability of FTLD-related TDP-43 mutations in both yeast and mammalian cell models. Moreover, we focus on nucleolin (NCL) gene, recently identified as a genetic suppressor of TDP-43 toxicity, through a thorough structure/function characterization aimed at understanding the role of NCL domains in rescuing TDP-43-induced cytotoxicity. Using functional and biochemical assays, our data demonstrate that the N-terminus of NCL is necessary, but not sufficient, to exert its antagonizing effects on TDP-43, and further support the relevance of the DNA/RNA binding central region of the protein. Concurrently, data suggest the importance of the NCL nuclear localization for TDP-43 trafficking, possibly related to both TDP-43 physiology and toxicity.

Restoration of Ultrafiltration Capacity of Peritoneal Membrane in Patients on CAPD

Among 55 uremic patients who entered our CAPD program, 7 of them showed a reduction or loss of the ultrafiltration capacity (UF) of the peritoneal membrane (PM). They have been treated with high dose of Furosemide (F) to force residual urine output. Four appeared «responders» to drug administration with a significant increase in urine volume, Na excretion and, within a week period gained their dry body weight (BW).

In the remaining 3 patients drug therapy resulted ineffective, and fluid removal was obtained by hemofiltration (HF).

In both groups we noted an increase in the UF capacity of PM when their dry BW was obtained either by pharmacological or technical approach.

These results support the assumption that the overhydration status of the PM plays a major role in maintaining the UF process.

Spontaneous Plasma Exchange by Gravity

Lysagth et al have reported a semplified model of spontaneous plasmapheresis by placing between an A-V shunt a conventional plasmafilter. On the basis of this experience we tried to make a further semplification of this apparatus using a single venous puncture, obtaining by gravity sufficient transmembrane pressure for plasma separation. By alternatively lowering and elevating the system, plasma is separated from the blood and packed red cells are reinfused after a new pass through the filter with FFP or plasma substitutes.

Combined hemodialysis-hemoperfusion in the treatment of secondary hyperparathyroidism of uremic patients

Hyperparathyroidism and its related symptoms such as bone pain, soft-tissue calcifications and pruritus often get worse during dialysis treatment. We have treated 12 cases among 170 patients on regular dialysis by using coated charcoal (150 g/cartridge) in combination with standard hemodialysis. During a 6-month treatment period, without changing medical therapy and diet regime, the patients reported a marked relief from pruritus. Parathyroid hormone (PTH) levels changed from 552 +/- 86 to 364 +/- 62 pg/ml (p less than 0.001) compared to the pretreatment period, Plasma PO4(3-) changed in the same period from 6.9 +/- 1.8 to 4.6 +/- 1.5 mg/dl (p less than 0.005). The results obtained indicate a relationship between PTH, serum plasma PO4(3-) levels and pruritus. The mechanism which may be involved is that hemoperfusion removes PTH excess by absorption. Our treatment reducing PTH levels resulted in a marked relief from pruritus and other symptoms, suggesting that patients in this condition, before undergoing surgical parathyroidectomy, may be usefully treated with this therapeutic modality.

On-line bioelectric impedance during haemodialysis: monitoring of body fluids and cell membrane status

We have measured by a computed integrated system (BIA 109, RJL AKERN) the changes of bio-impedance (BI) deriving from a tetrapolar system working on 800 microA, 50 kHz current, in 23 haemodialysed patients. Resistance (R) and reactance (Xc) have been continuously monitored during haemodialysis in each patient. Resistance was strictly inversely correlated to the decrease of body weight (r = 0.82). Also, Xc increased almost constantly. In most of the patients the increase of Xc was proportionally greater than R, resulting in an increase of phase angle (PA). However, Xc showed a transient decrease in response to seven severe symptomatic hypotensive episodes, whereas R maintained the increasing trend, causing a sharp reduction of phase angle. As Xc is an expression of storage of electrical charge by the cells acting as condensers, and phase angle quantifies the active capacitive component in relation to passive electrical resistance, these parameters may be important to evaluate cell membrane function. In fact, the univocal increase of R, Xc and phase angle observed during normal unevenful haemodialysis probably indicates improvement of cellular activities due to the depurative treatment. On the contrary, the transient reduction of Xc and phase angle observed during hypotensive crises may be an expression of cellular distress because of a too rapid ultrafiltration.

Removal of phosphate (Pi) by either bicarbonate dialysis or biofiltration in uremics

The kinetics of extra and intracellular red blood cell (RBC) Pi and its removal by different therapeutic modalities were evaluated in 30 uremic patients over a 6 mo. period. Acetate hemodialysis alone, combined with hemoperfusion, or associated once a week with plasma-perfusion sessions using an activated bauxite cartridge, bicarbonate dialysis either in single pass or in recirculating system (40 L) and biofiltration, were the depurative treatments employed. The treatments with acetate buffer showed a temporary intracellular shift of Pi at the end of the sessions with post-dialytic plasma Pi rebound. This was not evident with bicarbonate buffer and biofiltration where acidosis was corrected better, and similarly during plasma perfusion treatment because blood pH remained unchanged. These findings may explain the better plasma Pi level at the end of our study with these later therapeutic models compared to acetate dialysis alone or combined with hemoperfusion. In these conditions Pi removal is limited by the correction of acidosis which implies acetate metabolism with ATP activation leading to a transient Pi intracellular influx and a subsequent efflux into the extracellular compartment.

Spontaneous ascites filtration and reinfusion (SAFR) in cirrhotic patients

Since knowledge about the pathogenesis of hepato-renal syndrome (HRS) is incomplete, the therapy is empiric and supportive. While a number of specific therapeutic measures have been attempted, none has been proved to be of practical value. We describe a very simple technique for concentration of ascitic fluid obtained with spontaneous filtration by gravity. We have been treating with this new device 4 patients affected by HRS with ascites refractory to diuretics. We obtained a rapid disappearance of ascites and improvement in clinical condition. The simplicity and the ease of operation make this technique feasible for repeated chronic ambulatory treatment.

Spontaneous plasma exchange by gravity

Lysagth et al have reported a semplified model of spontaneous plasmapheresis by placing between an A-V shunt a conventional plasmafilter. On the basis of this experience we tried to make a further semplification of this apparatus using a single venous puncture, obtaining by gravity sufficient transmembrane pressure for plasma separation. By alternatively lowering and elevating the system, plasma is separated from the blood and packed red cells are reinfused after a new pass through the filter with FFP or plasma substitutes.

Restoration of ultrafiltration capacity of peritoneal membrane in patients on CAPD

Among 55 uremic patients who entered our CAPD program, 7 of them showed a reduction or loss of the ultrafiltration capacity (UF) of the peritoneal membrane (PM). They have been treated with high dose of Furosemide (F) to force residual urine output. Four appeared "responders" to drug administration with a significant increase in urine volume, Na excretion and, within a week period gained their dry body weight (BW). In the remaining 3 patients drug therapy resulted ineffective, and fluid removal was obtained by hemofiltration (HF). In both groups we noted an increase in the UF capacity of PM when their dry BW was obtained either by pharmacological or technical approach. These results support the assumption that the over-hydration status of the PM plays a major role in maintaining the UF process.

Hemodynamic evaluation during plasma-exchange with intermittent flow

Plasma-exchange (PE) represents an effective therapeutic approach employed in several immunological nephropathies, poisonings and various other diseases. Hemodynamic changes during intermittent flow PE were studied--using the thermodilution technique--in 8 patients (3 male and 5 female) aged between 36 and 73 years (mean 46.4). The mean values for the following parameters were measured before, during every cycle--exchanging about 300 ml of fresh frozen plasma--and at the end of the session: mean arterial pressure (MAP), heart rate (HR), cardiac index (Cl), stroke index (SI), total peripheral resistence (TPR), central venous pressure (CVP), pulmonary arterial pressure (PAP) and pulmonary capillary wedge pressure (PCWP). During the first exchange the systemic circulation showed hemodynamic changes similar that of an acute hemorrhagic condition: decrease in MAP (from 106 to 97 mmHg), Cl (from 4.27 to 3.7 L/m'/m2), SI (from 53 to 49 ml/beat/m2) and CVP (from 6.9 to 4.4 mmHg); increase in TPR (from 1230 to 1339) dynes/sec/cm-5), while HR showed only mild changes. In the following cycles all the parameters progressively returned toward the previous values. During the first cycle the pulmonary circulation showed a decrease in PAP (from 15.5 to 13 mmHg) and PCWP (from 8.9 to 6.6 mmHg). PAP also increased constantly in the following cycles reaching at the end of the session levels which were higher than the initial ones. Our data demonstrate that in PE treatment especially when is employed a low volume of fluid, has to be substituted at every cycle in order to prevent the major hemodynamic complications i.e. hypovolemic shock and heart failure.