Giovanni Piotti

The Syndrome of Inappropriate Antidiuresis: Pathophysiology, Clinical Management and New Therapeutic Options

Hyponatremia is a marker of different underlying diseases and it can be a cause of morbidity itself; this implies the importance of a correct approach to the problem. The syndrome of inappropriate antidiuresis (SIAD) is one of the most common causes of hyponatremia: it is a disorder of sodium and water balance characterized by urinary dilution impairment and hypotonic hyponatremia, in the absence of renal disease or any identifiable non-osmotic stimulus able to induce antidiuretic hormone (ADH) release; according to its definition, it is diagnosed through an exclusion algorithm. SIAD is usually observed in hospitalized patients and its prevalence may be as high as 35%. The understanding of the syndrome has notably evolved over the last years, as reflected by the significant change in the name, once the syndrome of inappropriate secretion of ADH (SIADH), today SIAD. This review is up to date and it analyses the newest notions about pathophysiological mechanisms, classification, management and therapy of SIAD, including vaptans.

Mesenchymal Stem Cells Infusion Prevents Acute Cellular Rejection in Rat Kidney Transplantation

Mesenchymal stem cells (MSC) are multipotent cells that differentiate into various mature cell lineages. MSC show immunomodulatory effects by inhibiting T-cell proliferation. We evaluated the effect of the infusion of MSC in rats experimental kidney transplantation. Sprague-Dawley transgenic rats (SD) able to express the green fluorescent protein (EGFP) were used as MSC donors. Syngeneic (Lewis to Lewis, n = 10) and allogeneic (Fischer to Lewis, n = 10) kidney transplantations were performed after bilateral nephrectomy. Five transplanted rats who received syngeneic grafts, were treated with 3 x 10(6) MSC (Gr B), while the other 5 did not received MSC (Gr A). Five rats with allogenic grafts received 3 x 10(6) MSC (Gr C) and another 5 did not receive MSC (Gr D). The MSC were infused directly into the renal artery of the graft. No immunosuppressive therapy was provided. The animals were killed after 7 days. Biochemical analysis for renal function, histological (Banff criteria) and immunohistological analysis (ED1+ and CD8+) were performed on treated animals. MSC improved kidney function in Gr B and D vs Gr A and C. The tubular damage appeared to be less severe among Gr B and Gr D with respect to Gr A and C (P < .01). Vasculitis was more accentuated in Gr A and C (P < .01). MSCs reduced the inflammatory infiltrate; in Gr B and D, the number of ED1+ cells was lower than in Gr A and C (P < .005), which was also observed for CD8+ cells (P < .05). Our study demonstrated that the infusion of MSC attenuated histological damage from acute rejection by reducing the cellular infiltration.

Which Is the Most Suitable and Effective Route of Administration for Mesenchymal Stem Cell-Based Immunomodulation Therapy in Experimental Kidney Transplantation: Endovenous or Arterial?

Immunomodulating cell therapy represents a new perspective for the control of cellular immune responses that determine the occurrence of acute rejection (ACR) in allo-transplantation. Mesenchymal stem cells (MSC) demonstrate immunoregulatory effects by inactivating T-cell components that regulate tissue damage in transplantation models. The presumed mechanism of action is recruitment of cells by a cytokine network. The purpose of this study was to test which route of administration (intra-arterial vs intravenous) was the most effective route to achieve immunomodulating effects in experimental rat kidney transplantation. Transgenic Sprague-Dawley rats (SD) expressing the enhanced green fluorescent protein (EGFP) at the somatic level were used as MSC donors: Allogeneic Fischer to Lewis grafts (n = 4 per group) were performed in rats after bilateral nephrectomy. In Gr B, 3 x 10(6) MSCs were infused into the renal graft artery, whereas in Gr C, they were infused into the tail vein. The untreated Gr A were a control group. No immunosuppressive therapy was administered. The animals were sacrificed at day 7 postoperatively. Biochemical analysis for renal function, histological (Banff criteria) and immunohistological (anti-EGFP-Immunoglobulin) analysis were performed on the transplanted animals. In Gr B, functional recovery was more rapid (creatinine: Gr B vs Gr C, P < .05). The inflammatory infiltrate in the graft was less in Gr B vs Gr C, with preservation of tubules, arteries, and glomeruli (P < .01). Intra-arterial infusion of MSCs was more effective to control ACR.

Mesenchymal stromal cells improve renal injury in anti-Thy 1 nephritis by modulating inflammatory cytokines and scatter factors

MSC (mesenchymal stromal cells) can differentiate into renal adult cells, and have anti-inflammatory and immune-modulating activity. In the present study, we investigated whether MSC have protective/reparative effects in anti-Thy1 disease, an Ab (antibody)-induced mesangiolysis resulting in mesangioproliferative nephritis. We studied five groups of rats: (i) rats injected with anti-Thy1.1 Ab on day 0 (group A); (ii) rats injected with anti-Thy1.1 Ab on day 0+MSC on day 3 (group B); (iii) rats injected with anti-Thy1.1 Ab on day 0+mesangial cells on day 3 (group C); (iv) rats injected with saline on day 0+MSC on day 3 (group D); and (v) rats injected with saline on day 0 (group E). Rats were killed on days 1, 3, 7 and 14. MSC prevented the increase in serum creatinine, proteinuria, glomerular monocyte influx and glomerular histopathological injury. Furthermore, MSC suppressed the release of IL-6 (interleukin-6) and TGF-β (transforming growth factor-β), modulated glomerular PDGF-β (platelet-derived growth factor-β), and reset the scatter factors and their receptors, potentiating HGF (hepatocyte growth factor)/Met and inactivating MSP (macrophage-stimulating protein)/Ron (receptor origin nantaise). Few MSC were found in the kidney. These results indicate that MSC improve anti-Thy 1 disease not by replacing injured cells, but by preventing cytokine-driven inflammation and modulating PDGF-β and the scatter factors, i.e. systems that regulate movement and proliferation of monocytes and mesangial cells.

Severe Symptomatic Hyponatremia During Sibutramine Therapy: A Case Report

Sibutramine, a serotonin reuptake inhibitor, currently is used in treatment of obesity. The known side effects of sibutramine, ie, hypertension and tachycardia, depend on its adrenergic and serotoninergic effects. We describe a case of life-threatening hyponatremia associated with sibutramine use in an obese woman. We hypothesize that sibutramine, through its effect on neurotransmitters, may induce antidiuretic hormone secretion and lead to a syndrome of inappropriate antidiuretic hormone secretion. We advise careful monitoring of water-electrolytic balance during sibutramine therapy.

Atraumatic Spleen Rupture in Dialyzed Patients: Clinical Report and Review of the Literature

Atraumatic spleen rupture (ASR) is a rare but lifethreatening event. It can present either with a dull and unspecific abdominal pain or with severe shock because of intraperitoneal hemorrhage. It requires prompt intensive medical support while preparations are made for emergency splenectomy. The term “atraumatic” should be used only in the absence of abdominal trauma, and thus 3 categories have been identified (1):