A polymerase chain reaction (PCR)-based assay using primers against the hepatitis C core gene has been described [Okamoto et al. (1992a): Journal of General Virology 73:673-679]. Within the two major HCV genotypes 1 and 2, the Okamoto system identifies two subtypes each (1a, 1b and 2a, 2b, respectively). Typing is achieved by a primary PCR with consensus primers followed by a nested PCR with type specific primers. The original assay was modified by addition of a parallel second PCR identifying the recently described major genotype 3. The assay also identifies in duplicate subtype 1b (type II by Okamoto), suggested to respond poorly to interferon. Reaction conditions were reviewed and melting temperatures of all typing primers equalised to increase strigency. The modified system functioned well and typing results were supported by partial core sequencing. The following distribution of genotypes was found in 53 hepatitis C virus (HCV) infected Swedish blood donors: genotype 1a (57%), 3 (19%), 1b (13%), and 2b (11%). In six recipients of HCV infected blood identified in a retrospective study, the recipient HCV genotype was identical to donor HCV genotype. Furthermore, in HCV positive couples identical genotype was observed when only one partner had an external risk factor; whereas genotypes were often diverse if both sex partners had parenteral risk factors. Finally, a cluster of hepatitis C cases in a haemodialysis unit was evaluated retrospectively. Eight patients had genotype 1b, two had mixed 1a and 1b, and one had type 1a. The modified HCV genotyping assay was of value in examining different epidemiological situations and can be expanded presumably to include future genotypes.
A therapeutic removal of antibodies may be achieved by immunoadsorption (IA) or by plasma exchange (PE). The aim of this prospective randomised study was to compare the efficacy of these different techniques with regard to treatment of patients with rapidly progressive glomerulonephritis (RPG) having at least 50% crescents. Forty-four patients with a RPG were included for treatment either by IA or PE (with albumin as substitution for removed plasma). All patients were additionally treated with immunosuppression. A median of 6 sessions of PEs were performed in 23 patients compared with 6 IAs in 21 patients. Goodpasture's syndrome (GP) was present in 6 patients (PE 3, IA 3). All of them started and ended in dialysis, two died. Among the remaining 38 patients (26 men, 12 women) 87% had antibodies to ANCA. Creatinine clearance for PE versus IA were at a median at start 17.1 and 19.8 ml/min, and at 6 months 49 and 49 ml/min, respectively. At 6 months 7 of 10 patients did not need dialysis (remaining: IA 0/5 and PE 2/5, n.s.). The extent of improvement did not differ between the groups. Three patients died during the observation period of 6 months (IA 2; PE 1, on HD). Although no difference was found between the IA or the PE group this study shows that the protocol used was associated with an improved renal function in most patients (except for Goodpasture's syndrome) whereas 70% of them could leave the dialysis program.
We examined the kinetics of contrast agent elimination during hemodialysis in 7 patients with end-stage renal disease on regular hemodialysis treatment (group I) and in 13 patients with impaired renal function (serum creatinine 214-657 μmol/l; group II). The nonionic agent iohexol was administered at a dose of 0.4-4.5 g/kg, and a 6-hour hemodialysis was performed with 1-18 h delay. This procedure removed 60-90% (mean 77%) of the iohexol present in the circulation at the start of dialysis treatment. The mean extraction ratio across the dialysis membrane was 0.47 and was inversely related to blood flow. The total clearance of iohexol was 70.4 ± 24.6 ml/min and was very close to dialyzer clearance, as estimated from blood flow and extraction ratio. The plasma iohexol level after dialysis was related to the dose administered, iohexol clearance, and the patients’ body weight. During peritoneal dialysis (36-60 liters dialysis fluid), 43-72% of the iohexol dose was removed from the patients’ circulation. In patients of group II no further impairment of the renal function (increase of serum creatinine) in conjunction with angiography was observed. We conclude that hemodialysis and peritoneal dialysis are effective methods for removal of iohexol. Our observations suggest also that accelerated elimination of contast media by prophylactic dialysis can be beneficial in preventing further reduction in renal function after angiographic procedures in high-risk patients.
The risk of a marked and sustained reduction in renal function after administration of an iodine contrast medium is low with modern angiographic techniques. Hemodialysis reduces levels of contrast media in plasma but does not reduce the incidence of contrast-medium-induced nephrotoxicity in the GFR range from 10 to 25 ml/min.
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