Role of exonuclease in the specificity of bacteriophage T7 DNA packaging

During morphogenesis in vivo, bacteriophage T7 packages and cuts to mature size an end-to-end concatemer of its nonpermuted, terminally repetitious, double-stranded, mature DNA. Efficient production (90-100%) and packaging (20-35%) of concatemers has also been demonstrated in extracts of T7-infected cells (in vitro) (Son, M., Hayes, S. J., and Serwer, P. [1988] Virology 162, 38-46). By use of both this procedure of in vitro DNA packaging and in-gel hybridization to packaged DNA fractionated by agarose gel electrophoresis, the specificity of packaging in vitro is found to depend on the presence of T7 gene 6 exonuclease (p6). In the absence of p6 in vitro, no concatemerization is detected and packaging of DNA nonhomologous to T7 DNA (bacteriophage P22 DNA) is as efficient (0.05-1.1%) as the packaging of monomeric T7 DNA. Addition of p6 in vitro both stimulates the concatemerization-packaging of T7 DNA and suppresses the packaging of P22 DNA. The packaging efficiency for concatemeric T7 DNA is 29-611 x higher than that for monomeric T7 DNA. Inhibition of the packaging of P22 DNA by p6 is correlated with the formation of single-stranded P22 DNA ends. These data are explained by the hypothesis that a DNA molecule with a single-stranded end is packaged less efficiently than the same DNA without the single-stranded end. Testing this hypothesis in vivo reveals that both p6 and gene 3 endonuclease contribute to suppressing the packaging of host DNA.     

Early prednisone therapy in Henoch-Schönlein purpura: a randomized, double-blind, placebo-controlled trial

OBJECTIVE: To evaluate the efficacy of early prednisone therapy in preventing renal and treating extrarenal and renal symptoms in Henoch-Sch?nlein purpura (HSP) in a placebo-controlled trial. STUDY DESIGN: A total of 171 patients (84 treated with prednisone and 87 receiving placebo) were included and followed up for 6 months. The endpoints were renal involvement at 1, 3, and 6 months and healing of extrarenal symptoms. The analyses were performed on an intent-to-treat basis. RESULTS: Prednisone (1 mg/kg/day for 2 weeks, with weaning over the subsequent 2 weeks) was effective in reducing the intensity of abdominal pain (pain score, 2.5 vs 4.8; P = .029) and joint pain (4.6 vs 7.3; P = .030). Prednisone did not prevent the development of renal symptoms but was effective in treating them; renal symptoms resolved in 61% of the prednisone patients after treatment, compared with 34% of the placebo patients (difference = 27%; 95% confidence interval = 3% to 47%; P = .024). CONCLUSIONS: The general use of prednisone in HSP is not supported, but patients with disturbing symptoms may benefit from early treatment, because prednisone reduces extrarenal symptoms and is effective in altering (but not preventing) the course of renal involvement.     

Plasma cell-free DNA in patients needing mechanical ventilation

Introduction  

Concentrations of plasma cell-free DNA are increased in various diseases and have shown some prognostic value in many patient groups, including critically ill patients. Pathophysiological processes behind the need for mechanical ventilation and the treatment itself could raise plasma levels of cell-free DNA. We evaluated levels of plasma cell-free DNA and their prognostic value in patients needing mechanical ventilation.     

Uric acid and cognition in Parkinson's disease: a follow-up study

Cognitive changes are common in Parkinson's disease (PD). Low plasma uric acid (UA) level is associated with risk of PD and predicts faster progression of motor symptoms in established disease. Whether UA levels predict cognitive changes has not been studied. In a crossectional study, our group has previously shown an association of plasma and urine UA levels with cognition in PD. The aim of the present controlled longitudinal study was to examine the evolution of cognitive changes and the prognostic value of the UA levels on cognition in the previously reported PD-patient cohort. Of the original 40 patients, 31 were available for follow-up after three years. Both plasma and daily urine UA levels were measured, nutrition was evaluated using 4-day dietary recall diary and cognition was assessed by a thorough neuropsychological examination including computerized tasks with Cognispeed?. The plasma and urine UA levels of the patients remained stable during the follow-up. At the same time, the rate of cognitive decline was unexpectedly slow. A statistically significant deterioration was noted in verbal fluency (p=0.04) and in Cognispeed?'s vigilance task (p=0.0001). In forward linear regression analysis only the baseline daily urine UA level contributed to verbal fluency (p=0.01), picture completion (p=0.001), block design (p=0.006), vigilance (p=0.006), subtraction (p=0.01) and statement verification (p=0.04) tasks. The implications of the study results are discussed.     

Sustained remission and reduced radiographic progression with combination disease modifying antirheumatic drugs in early rheumatoid arthritis

OBJECTIVE: To study sustainability of remission and good treatment response, and the association of both with radiographic progression, in early rheumatoid arthritis (RA) in the Finnish Rheumatoid Arthritis Combination Therapy trial (FIN-RACo). METHODS: Patients were randomized to receive either a combination of disease modifying antirheumatic drugs (DMARD; COMBI, n = 97) or a single DMARD (SINGLE, n = 98). Remission was defined according to modified American College of Rheumatology (ACR) remission criteria and Disease Activity Score 28 joint count (DAS28) < or = 2.6, and sustained remission as presence of remission at 6, 12, and 24 months. Good treatment response was defined as DAS28 (3/4) 3.2 and decrease of DAS28 >1.2. RESULTS: In 169 patients with complete data, 33 (42%) COMBI and 18 (20%) SINGLE patients achieved modified ACR remission at 2 years, which was sustained in 11 (14%) COMBI and 3 (3%) SINGLE patients. Fifty-four (68%) COMBI and 37 (41%) SINGLE patients were in DAS28 remission at 2 years, which was sustained in 40 (51%) COMBI and 14 (16%) SINGLE patients. Good treatment response was sustained in 67% of COMBI and 27% of SINGLE patients. Over 2 years, the Larsen score increased by a median of 1 (95% CI 0-2) in patients in sustained DAS28 remission compared to 4 (95% CI 2-16) in patients who were in DAS28 remission at 6 months but lost it later; and by 6 (95% CI 2-10) in patients who were not in remission at 6 months. CONCLUSION: A remarkable proportion of patients with early RA treated with combinations of DMARD were in remission at 2 years, and remission was more often sustained compared to patients treated with a single DMARD. Sustained remission protects against radiographic joint damage.     

Disease activity score 28 as an instrument to measure disease activity in patients with early rheumatoid arthritis

OBJECTIVE: To examine the influence of components of the Disease Activity Score 28 (DAS28) [tender joint count (TJC), swollen joint count (SJC), patient's general health (GH), and erythrocyte sedimentation rate (ESR)] on the total DAS28 score, and overlapping of the 4 individual components in rheumatoid arthritis (RA) patients with low, moderate, or high disease activity. METHODS: The effect of each component was studied in the FIN-RACo trial patients at 6 months and in a "theoretical model," where each component of the DAS28 ranged as follows: TJC and SJC from 0 to 28, GH from 0 to 100, and ESR from 1 to 100, while the other 3 components were 0 (ESR1). Overlapping of the components was studied in the FIN-RACo trial patients at 6 months with low (DAS28 < or = 3.2), moderate (DAS28 > 3.2 and < or = 5.1), and high (DAS28 > 5.1) disease activity. The higher limit for overlapping was defined as the highest SJC in the low disease activity group, and the lower limit as the lowest SJC in the high disease activity group; the percentage of patients who fall between these limits represent overlapping in SJC. Overlapping was calculated similarly concerning TJC, ESR, and GH. RESULTS: ESR had the greatest effect on DAS28, followed by TJC, GH, and SJC, while in the "theoretical model" TJC had the greatest effect on the DAS28, followed by ESR, SJC, and GH. At 6 months, overlapping was present in 54%, 45%, 49%, and 31% of patients in SJC, TJC, GH, and ESR, respectively. CONCLUSION: In real-life patients, ESR had the greatest effect of the 4 components of DAS28 on the total DAS28 score. The values of the individual components of DAS28 overlap considerably among the 3 disease activity groups.