A double-blind, randomised- placebo, controlled, parallel group, multicentre, flexible-dose escalation study to assess the efficacy and safety of sildenafil administered as required to male outpatients with erectile dysfunction in Korea.

The efficacy and safety of sildenafil was evaluated in a randomiSed, double-blind, placebo-controlled, flexible-dose study in Korean men aged 28-78 y with erectile dysfunction (ED) of broad-spectrum aetiology and more than 6 months duration. A total of 133 patients were randomised at six centres in Korea to receive either sildenafil (50 mg initially, increased if necessary to l00 mg or decreased to 25 mg depending on efficacy and tolerance) (n=66) or matching placebo (n=67) taken on an 'as needed' basis l h prior to anticipated sexual activity for a period of 8 weeks. At the end of this time, the primary efficacy variables relating to the achievement and maintenance of erections sufficient for sexual intercourse, and the secondary efficacy variables, which included: (1) the five separate domains of sexual functioning of the International Index of Erectile Function (IIEF) scale, (2) the percentage of successful intercourse attempts, and (3) a global assessment of erections, were all statistically significantly improved by sildenafil in comparison with placebo (P&<0.0001). Treatment-related adverse events occurred in 56.1% of patients receiving sildenafil and 20.9% receiving placebo. The most common adverse events with sildenafil were vasodilatation (flushing), headache and abnormalities in colour vision (31.8, 22.7 and 6.1% of patients, respectively), and most were mild in nature. The efficacy and safety of sildenafil in this population of Korean men appears similar to that reported in other studies in western populations.

Multicenter study of the treatment of erectile dysfunction with transurethral alprostadil (MUSE) in Korea.

A Korean multicenter study was conducted to assess the effectiveness of transurethral alprostadil with MUSE in 334 subjects with chronic erectile dysfunction (ED) who were enrolled in 21 clinical centers. Patients with psychogenic impotence comprised about 30% of subjects. Intraurethral alprostadil was titrated in a stepwise fashion in the clinics from 250 to 500 or 1000 mcg based on erectile response and tolerability. The erectile responses were evaluated using an erection assessment scale (score of 1-5). The dose that produced a maximal penile response of score 5 (full rigid erection) or 4 (full tumescence, partial rigidity) was selected for home treatment. Patients who showed partial erection (score of 3) with 1000 mcg were also included in the home-treatment group. In-clinic phase: 198 men (59.3%) had maximal penile responses of score 4 or 5. The rate of maximal responses was not related to patient age, etiology or duration of the ED. A total of 228 (68.3%) men progressed to home treatment. The overall level of comfort of the transurethral alprostadil was rated as uncomfortable or very uncomfortable in 12%. Home phase: During the two-month period of home treatment, 178 (78.1%) men had successful sexual intercourse at least once, and 78.2% of administrations (1976) resulted in successful intercourse. The main causes of drop-out were insufficient erectile response in 27 men (11.8%), adverse reactions (mostly penile or urethral pain) in 7 (3.1%) or both in 7 (3.1%). In conclusion, transurethral alprostadil could be a suitable treatment option for patients with ED regardless of age and etiology of ED. Efficacy in an Asian population (Korea) is comparable to that reported previously in Caucasians.

Detection of novel beta 2-microglobulin in the serum of hemodialysis patients and its amyloidogenic predisposition.

Serum from 8 undialyzed patients and 30 dialyzed patients was examined by immunoblotting using anti beta 2-microglobulin (beta 2M) serum after two-dimensional gel electrophoresis (2.DE). One major spot and three minor spots were detected in the ultrafiltrate as well as in the serum. One major spot was determined to be native beta 2M and three minor spots were found to be novel beta 2M. Novel beta 2M had a lower molecular weight (MW) and a higher acidic isoelectric point (pI). Novel beta 2M was recognized in the sera of 5 out of 20 hemodialysis (HD) patients without carpal tunnel syndrome (CTS), 2 of whom had been on HD from 5 to 10 years and 3 for more than 10 years, as well as in the sera of all 10 patients with CTS. By chromatofocusing, pI of novel beta 2M was 5.2, while pI of native beta 2M was 5.7. When the tissue specimen of transverse carpal ligament of 2 HD patients with CTS was examined by immunoblotting after 2.DE, the spot of novel beta 2M was larger than that of native beta 2M. It is possible that some metabolic abnormality of beta 2M occurs through long-term hemodialysis, and it is possible that novel beta 2M might relate to amyloidogenic predisposition.

Detection of electrophoretic heterogeneity of serum beta 2-microglobulin in chronic renal failure.

To determine the metabolic abnormality of serum beta 2-microglobulin (beta 2m) from patients with chronic renal failure, electrophoretic heterogeneity of beta 2m (novel beta 2m) was examined by analyzing 10 microliters or 50 microliters serum samples on immunoblotting using anti beta 2m serum after two dimensional electrophoresis or by chromatofocusing. Novel beta 2m had a lower molecular weight and a higher acidic isoelectric point. The serum levels of beta 2m might be dependent on the dialysis duration. Changes of conformation or amino acid composition in native beta 2m might occur in patients with chronic renal failure, and these changes may begin prior to the initiation of dialysis.

Comparison of serum protein removal in haemodialysis therapy by partly protein-permeable haemodialysers.

Partly protein-permeable haemodialysers were evaluated during haemodialysis therapy for removal of serum low-molecular-mass proteins (10,000-76,000) in patients with chronic renal failure. The six haemodialyser membranes used were cuproammonium rayon (CL-S12W), cellulose acetate (Duo-Flux HP and FF-22), ethylene-vinyl alcohol copolymer (KF-101-15), polyacrylonitrile (H12-2400S) and polymethyl methacrylate (BK2.0H). The analysis was carried out by gel permeation chromatography, sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and two-dimensional gel electrophoresis (2-DE). The removal of ten serum proteins per haemodialysis therapy was also carried out by the immunodiffusion method. The protein removal in each haemodialyser is qualitatively comparable to that obtained by SDS-PAGE and 2-DE. beta 2-Microglobulin in the haemodialysate obtained with BK2.0H was removed to a lesser extent than that from the other haemodialysers, which seems to be the reason for its adsorption in the BK2.0H haemodialyser, which contains a polymethyl methacrylate membrane. The amount of serum protein excretion during haemodiafiltration treatment using the partly protein-permeable haemodialysers decreased in the order KF-101-15C greater than BK2.0H greater than CL-S12W greater than Duo-Flux HP greater than FF-22 greater than H12-2400S.

Selective inhibition of erythropoiesis by sera from patients with chronic renal failure.

The pathogenesis of anemia in patients with chronic renal failure was studied by analyzing the effect of uremic sera on the in vitro colony growth of erythroid (CFU-E) and granulocyte-macrophage (CFU-GM) progenitor cells. Uremic sera from 20 of 30 patients inhibited erythroid colony growth below 70% of control even when cultured with normal human bone marrow of the same blood type. On the other hand, only one of the sera inhibited colony growth of CFU-GM as compared with normal sera. On Sephadex G-15 gel filtration, the CFU-E-inhibiting activity appeared in two different fractions: the void volume peak and the delayed eluant before the second peak. The inhibiting activity in the former fraction was noted only in uremic sera. The results of this study suggest the existence of a serum inhibitor(s) of erythropoiesis with a relative molecular mass of more than 1500 Da which are virtually impossible to dialyze by conventional membranes.

Separation of an inhibitor of erythropoiesis in "middle molecules" from hemodialysate from patients with chronic renal failure.

A "middle molecule" inhibitor of erythropoiesis in patients with chronic renal failure was separated from a large amount of hemodialysate. Hemodialysate was passed through Amberlite XAD-4 resin, Sephadex G-50 gel, and DEAE-Sephadex A-25, followed by reversed-phase liquid chromatography. The erythroid colony assay (CFU-E) was used to detect the inhibitory effect of the sample solution. Certain fractions from the DEAE-Sephadex A-25 column showed a dose-related inhibition of CFU-E formation as great as that of standard spermine. The inhibitory effect of these fractions decreased to the control value after proteolytic digestion. The inhibitor was eluted from the liquid-chromatographic column by a solvent gradient containing 390 to 425 mL of methanol per liter. These results suggest there is an inhibitor of CFU-E with a relative molecular mass of 1000 to 10 000 and an active site composed of peptide. This technique may prove useful for separation of the inhibitor of erythropoiesis in uremic body fluid.

Efficient purification of human plasma beta 2-microglobulin from the haemodialysate of a patient with chronic renal failure by use of high-performance liquid chromatography.

Human plasma beta 2-microglobulin was isolated in a good yield (more than 80%) from the haemodialysate (blood ultrafiltrate) of a patient with chronic renal failure. The isolation procedure consisted of Sephadex G-100 gel filtration and two steps of high-performance liquid chromatography: reversed-phase high-performance liquid chromatography and gel permeation chromatography. The purified beta 2-microglobulin was homogeneous by sodium dodecyl sulphate polyacrylamide gel electrophoresis and two-dimensional electrophoresis.

Serum levels of polyamines in patients with chronic renal failure.

Serum levels of total putrescine, cadaverine, spermidine and spermine were measured in 10 normal subjects, 11 nondialyzed patients with chronic renal failure, and 25 patients undergoing maintenance hemodialysis. The measurement of the serum levels of four polyamines was done with high-performance cation-exchange chromatographic separation and fluorometric detection using o-phtalaldehyde. In normal subjects, the serum levels of putrescine and spermine were 0.24 +/- 0.09 and 0.20 +/- 0.05 nmoles/ml. In patients with chronic renal failure, the levels of polyamines were obtained in the order of putrescine, cadaverine, spermidine, and spermine: 0.51 +/- 0.15; 0.05 +/- 0.01; 0.34 +/- 0.08; and 0.05 +/- 0.04 nmoles/ml. In dialyzed patients, predialysis values of polyamines in the same order as above were: 0.88 +/- 0.31; 0.12 +/- 0.10; 0.67 +/- 0.31; and 0.09 +/- 0.08 nmoles/ml. The results show that, compared to normal subjects, the serum levels of all four polyamines are significantly elevated either in nondialyzed patients with chronic renal failure or in dialyzed patients. In dialyzed patients, the postdialysis putrescine and spermidine levels are significantly low. Serum levels of putrescine and spermidine are both significantly correlated with serum urea nitrogen and serum creatinine in a combined group of normal subjects and patients with chronic renal failure. In dialyzed patients, none of the four polyamine serum levels show correlations either with serum urea nitrogen or serum creatinine; with hematocrit, only spermine exhibits a correlationship, whereas other polyamines do not.

Determination of polyamines in hydrolysates of uremic plasma by high-performance cation-exchange column chromatography.

The levels of putrescine, cadaverine, spermidine and spermine in uremic plasma were determined with an automatic polyamine analyzer with a 7.5 X 0.2 cm I.D. cation-exchange column using a stepwise sodium chloride gradient. All four polyamines were higher in ten patients with chronic renal failure than in eight normal subjects. The total polyamine content was also measured in the patients' plasma before and after maintenance dialysis; putrescine and spermidine levels were significantly lowered by the procedure.

Analytical study for separation of middle molecules.

A 3-step chromatography procedure was employed to perform a profiling analysis of middle molecular substances accumulating in uremia serum. In the first step, gel chromatography on Sephadex G-15 columns (8 x 100 cm) was performed, and the two peak fractions (3,4) appearing near the vitamin B12 elution position were taken, lyophilized, and rechromatography on Bio-Gel P-4 (super fine) column was undertaken on each. The peak 3 from Sephadex G-15 was further fractionated on Bio-Gel P-4 into 4 peaks (a, b, c, d). Moreover, the peak 4 was fractionated into a further two peaks, d and e. Using reversed-phase chromatography on Nucleosil 5C18 (0.4 x 20 cm) with Bio-Gel P-4, the peaks for approximately 100 middle molecules have been separated. It is considered that, through structural determination of each of these middle molecule peaks, their possible toxicity can be ascertained and that the substances to be removed clinically can be clarified.