Purification of human erythropoietin to homogeneity by a rapid five- step procedure

Human urinary erythropoietin (Ep) has been purified using a simple five- step procedure to yield preparations with potencies of 80,000 U/mg in 25% yield. The five steps involve: (1) affinity chromatography on CM Affi-Gel Blue, (2) chromatofocusing, (3) wheat germ lectin (or hydroxylapatite) chromatography, (4) reverse-phase high-performance liquid chromatography (HPLC) using a phenyl column, and (5) preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Ep activity was determined at each stage using a highly sensitive and specific in vitro assay that measures [3H]-thymidine incorporation into erythroid cells from spleens of phenylhydrazine-treated mice. The step 5 material was also tested with the in vivo polycythemic mouse assay procedure and was found to have a similar potency to that obtained in the [3H]-thymidine in vitro assay. SDS-PAGE analysis of the step 5 material revealed a single 38.5-kd band that comigrated with Ep bioactivity. Homogeneity was confirmed by amino acid sequence analysis. Starting with urine containing approximately 13 U/mg of protein, the cumulative degrees of purification achieved with each step were: step 1,25-fold; step 2, 75-fold; step 3, 300-fold; step 4, 1,500-fold; and step 5, 5,000-fold. Corresponding overall recoveries after each step were: greater than 100%, 70%, 45%, 30%, and 25%. These recoveries could be obtained when as little as 5,000 U of starting urinary Ep were processed because of the introduction of Tween 20 and SDS into buffers used at various stages of the purification procedure. In addition, a rapid method for determining Ep purity which involves reverse-phase HPLC of trypsinized 125I-labeled Ep is presented. This allows the establishment of purity with far less material than is required for amino acid sequencing.     

Transfection of wild-type deoxycytidine kinase (dck) cDNA into an AraC- and DAC-resistant rat leukemic cell line of clonal origin fully restores drug sensitivity

The AraC-resistant rat leukemic cell line RO/1-A has been shown to have a typical deoxycytidine kinase (DCK)-deficient phenotype and cannot metabolize the antileukemic drugs cytarabine (AraC) and decitabine (DAC). To investigate the relative contribution of mutations in the dck gene to the development of in vitro-induced AraC-resistance, a neomycin selectable plasmid construct harboring the wild-type dck coding region was transfected into RO/1-A. Polymerase chain reaction analysis confirmed the presence of vector DNA in the target cells (RO/1-ADCK) that were stably transfected and monitored over a period of 14 weeks. Northern and Western blot analysis showed restoration of dck mRNA and protein expression. Initial rate measurements of DCK activity showed that Km values for dck were only slightly altered as a result of transfection, whereas strongly increased Vmax values were observed, resulting in a 12-fold increased phosphorylation efficiency for both dC and AraC, compared with the AraC-sensitive parental cell line RO/1 from which the RO/1-A was originally derived. In vitro sensitivity to AraC- and DAC-mediated cytotoxicity was fully restored in RO/1-ADCK. The data pinpoint acquired DCK deficiency caused by mutations of the dck gene as the major cause of AraC resistance in this model.     

Comparison of cyclosporine and D-penicillamine for rheumatoid arthritis: a randomized, double blind, multicenter study

Ninety-two patients with active rheumatoid arthritis (RA) were entered in a randomized double blind study of 24 weeks comparing cyclosporine (initial daily dose 5 mg/kg) with D-penicillamine (initial daily dose 250 mg). The groups were well balanced in baseline characteristics. In the cyclosporine group, 10 patients stopped prematurely, one because of inefficacy. In the D-penicillamine group, 9 patients stopped prematurely, 3 because of inefficacy. The 2 antirheumatic drugs were equally effective in reducing disease activity, except for a significant (p = 0.005) decrease in erythrocyte sedimentation rate with D-penicillamine treatment. We conclude that under the conditions of this trial, cyclosporine can serve as an alternative to D-penicillamine for the treatment of patients with RA.     

Long acting drug combinations in rheumatoid arthritis: a formal overview

We compared the benefits and risks of combinations of long acting antirheumatic drugs with those of the same drugs used singly in the treatment of rheumatoid arthritis. We searched the literature through MEDLINE (1966-89), Index Medicus (1956-65), Excerpta Medica (1982-89), Science Citation Index (1982-89), and bibliographic review of located articles. Of a total of 341 citations, we identified 7 prospective trials that specifically addressed the stated purpose. We independently assessed the quality of the selected trials, using published methodological criteria and summarized the effect of treatment on arthritis activity and the incidence of side effects. The trials we evaluated tested various drug combinations. Because of deficiencies in methods and reporting, only 3 trials had sufficient quality to yield strong or moderately strong evidence. None conclusively demonstrated benefit of a drug combination: 2 suggested such benefit, including 1 also suggesting increased toxicity; the 3rd suggested only increased toxicity. The other 4 trials yielded weak evidence to support both increased efficacy and toxicity. The advantages of any antirheumatic drug combination remain unproven. Because these advantages are likely to be modest, they can only be shown in rigorously designed trials enrolling large numbers of patients. Methods and reporting of antirheumatic drug trials should be standardized to allow combining of study results.     

Cardiovascular abnormalities in Marfan syndrome]

During the period February to December 1990, 52 adult patients were referred to our clinic for evaluation of the presence of the Marfan syndrome. In 24 out of 52 patients the Marfan syndrome was diagnosed. Cardiac abnormalities were found in all patients: mitral insufficiency because of mitral valve prolapse (83%), aortic dilatation (67%), aortic insufficiency (38%), tricuspid valve insufficiency with or without tricuspid valve prolapse (17%) and atrial septal defect (4%). In 3 patients an aneurysm of the ascending aorta was found. Early recognition of the Marfan syndrome is relevant for prevention of the life threatening complication of aortic dissection. In patients with valve abnormalities endocarditis prophylaxis is advised. A Marfan outpatient clinic offers optimal diagnostic possibilities.