[Polyomavirus infection in an immunocompetent patient and literature overview]. / Infezione da Polymavirus in paziente immunocompetente e revisione della letteratura.

BACKGROUND: Polyoma virus (PV) is a double-stranded DNA virus, member of the Papovaviridae family. BKV and JCV are the most studied in human pathology, whereas simian virus 40 (SV40) is pathogenic in the monkey and has been implicated in human carcinogenesis. PV is associated with renal and urinary tract pathology. The initial infection by PV occurs in childhood, probably by airways, and is usually asymptomatic. Subsequently, it remains latent in kidneys, tonsils and CNS and may reactivate in concomitance with significant T-cell dysfunction. Infection in immunocompromised patients can be clinically relevant. However, asymptomatic viruria may be detected in 0.3 % of individuals without a known history of immunodeficiency. CASE REPORT: We describe the case of a male patient, aged 31, admitted to our Unit for arterial hypertension and urinary abnormalities. He had a history of hemorrhagic cystitis in 1996 and persistent microscopic hematuria thereafter. Renal function was normal, arterial pressure well controlled with an ACE-inhibitor; urine culture was negative and most of the immunologic and rheumatologic tests were normal, with the exception of slightly reduced levels of C3 and an inverted CD4/CD8 ratio. Serology for HCV, HBV, HIV and screening for tumor markers were negative. Renal ultrasonography displayed an increased reflectivity, as seen in medical nephropathies; no nephrolithiasis was found. Urinary cytology showed "decoy cells", as typically found in PV infection, whose presence was confirmed by n-PCR. Diagnosis at discharge from the hospital was primary arterial hypertension and urinary JCV infection. Currently, no treatment of proven efficacy against PV is available. CONCLUSIONS: We think that there is an increasing amount of evidence to include screening for PV in the diagnosis of urinary tract abnormalities of unknown origin, even in apparently immunocompetent patients. Urinary cytology, in experienced hands, may be a useful and relatively inexpensive first step diagnostic tool.

Regulation of nitric oxide synthesis in uraemia.

Nitric oxide (NO) is a cell-to-cell mediator involved in the regulation of vascular tone and in the mechanisms of host defence. Since uraemic syndrome is characterized by abnormalities in blood pressure and flow and by impairment of white cell function, we studied the regulation of nitric oxide synthase (NOS) activity by uraemic plasma. We used three different cellular types having different levels of NOS activity: tEnd.1 murine endothelial cell line transformed by mT oncogene of polyomavirus had a high NOS activity and expressed endothelial-NOS (eNOS) and inducible-NOS (iNOS) isoforms; human endothelial cells from cord umbilical vein (HUVEC) had low enzymatic activity and expressed only eNOS; finally, J774 murine macrophage line was characterised by iNOS induced after treatment with cytokines. We demonstrated that most (79%) of end-stage uraemic plasma studied inhibited NOS activity in tEnd.1 and in cytokine induced -J774, whereas they were ineffective on HUVEC. Twenty percent of plasma samples (14 of 67) activated NOS activity in tEnd.1 and in J774 cells, but not in HUVEC, suggesting the presence of molecule(s) which influence iNOS. The effect of plasma was not dependent on the type of haemodialysis treatment. A great number of plasmas from patients with moderate renal failure also inhibited NOS activity in tEnd.1, suggesting that the accumulation of molecules affecting NOS was caused by the renal failure rather than the haemodialytic treatment. However, the haemodialysis modified the effect of plasmas on NOS activity. Plasma taken after haemodialysis session showed a reduced inhibitory activity in tEnd.1 and in some cases it enhanced NOS activity. Simultaneously, molecules reducing NOS activity accumulated in the ultrafiltrate. The plasma concentration of NG-NG dimethyl-L-arginine (asymmetrical dimethylarginine, ADMA), an inhibitor of NOS, increased in end-stage uraemic patients and was reduced by haemodialysis. However, the concentrations reached in uraemic plasmas were lower than the ADMA IC50 on tEnd.1 NOS, indicating that this compound contributes with other molecules to the inhibitory effect of uraemic plasma. Haemodialysis reduced also the enhanced effect exerted by some plasmas on NOS in J774. Therefore, the effect of end-stage uraemic plasma on NOS activity derive from the balance between inhibitors and activators.

[The lipid model in hemodialyzed patients]. / Il modello lipidico negli emodializzati.

In the context of metabolic alteration in dialysis patients the Authors have studied the characteristics, incidence, pathogenesis, effect of dialysis, atherogenic risk and therapeutic approach to hyperlipemia in hemodialysis patients. Hypertriglyceridemia secondary to reduced lipolytic activity is the most frequent alteration observed in hemodialytic patients (36.7% of cases). In addition, hemodialysis reduces the levels of lipoprotein in the blood whereas the atherogenic role of hyperlipemia does not appear to be as important as that of arterial hypertension and smoking. Simvastatin breaks down the lipidic fractions which are involved in atherogenesis and coronary cardiopathy, thus acting as a valuable prevention against cardiovascular involvement in dialysis.