The dynamic architecture of the metabolic switch in Streptomyces coelicolor

[EN] Background: During the lifetime of a fermenter culture, the soil bacterium S. coelicolor undergoes a major metabolic switch from exponential growth to antibiotic production. We have studied gene expression patterns during this switch, using a specifically designed Affymetrix genechip and a high-resolution time-series of fermenter-grown samples.Results: Surprisingly, we find that the metabolic switch actually consists of multiple finely orchestrated switching events. Strongly coherent clusters of genes show drastic changes in gene expression already many hours before the classically defined transition phase where the switch from primary to secondary metabolism was expected. The main switch in gene expression takes only 2 hours, and changes in antibiotic biosynthesis genes are delayed relative to the metabolic rearrangements. Furthermore, global variation in morphogenesis genes indicates an involvement of cell differentiation pathways in the decision phase leading up to the commitment to antibiotic biosynthesis.Conclusions: Our study provides the first detailed insights into the complex sequence of early regulatory events during and preceding the major metabolic switch in S. coelicolor, which will form the starting point for future attempts at engineering antibiotic production in a biotechnological settingSIWe are very grateful to Mervyn Bibb for his generous support with the Affymetrix custom microarray design. We acknowledge the excellent technical help of K. Klein, S. Poths, M. Walter, A. Øverby and E. Hansen. This project was supported by grants of the ERA-NET SySMO Project [GEN2006-27745-E/SYS]: (P-UK-01-11-3i) and the Research Council of Norway [project no. 181840/I30

y Integrated analysis of 8-week glecaprevir/pibrentasvir in Japanese and overseas patients without cirrhosis and with hepatitis C virus genotype 1 or 2 infection

AbbVi

The dynamic architecture of the metabolic switch in Streptomyces coelicolor

Background: During the lifetime of a fermenter culture, the soil bacterium S. coelicolor undergoes a major metabolic switch from exponential growth to antibiotic production. We have studied gene expression patterns during this switch, using a specifically designed Affymetrix genechip and a high-resolution time-series of fermenter-grown samples. Results: Surprisingly, we find that the metabolic switch actually consists of multiple finely orchestrated switching events. Strongly coherent clusters of genes show drastic changes in gene expression already many hours before the classically defined transition phase where the switch from primary to secondary metabolism was expected. The main switch in gene expression takes only 2 hours, and changes in antibiotic biosynthesis genes are delayed relative to the metabolic rearrangements. Furthermore, global variation in morphogenesis genes indicates an involvement of cell differentiation pathways in the decision phase leading up to the commitment to antibiotic biosynthesis. Conclusions: Our study provides the first detailed insights into the complex sequence of early regulatory events during and preceding the major metabolic switch in S. coelicolor, which will form the starting point for future attempts at engineering antibiotic production in a biotechnological setting

Journal of Hepatology

Texto completo. Acesso restrito. p. 452–459Background & Aims: Therapeutic options for patients failing hepatitis C retreatment are limited. EPIC3 included a prospective trial assessing long-term peginterferon alfa-2b (PegIFNa-2b) maintenance therapy in patients with METAVIR fibrosis scores (MFS) of F2 or F3 who previously failed hepatitis C retreatment. Methods: Patients with F2/F3 MFS who failed retreatment were randomized to PegIFNa-2b (0.5 lg/kg/week, n = 270) or observation (n = 270) for 36 months. Blinded liver biopsies obtained before retreatment and after maintenance therapy were evaluated using MFS and activity scores, and confirmatory testing was performed using FibroTest and ActiTest. Results: In total, 348 patients had paired biopsies: 192 patients had missing post-treatment biopsies and were considered as having no change in fibrosis/activity scores. In total, 16% of patients receiving PegIFNa-2b and 11% of observation patients had improvement in MFS (p = 0.32). More PegIFNa-2b than observation patients had improvement in activity score (20% vs. 9%; p 2.5 years, improvement in MFS or activity score was more common with PegIFNa-2b than observation (21% vs. 14%, p = 0.08 and 26% vs. 10%, p <0.001). FibroTest and ActiTest evaluations indicated significant benefit associated with PegIFNa-2b in terms of reduced fibrosis progression and improved activity score. The safety profile of PegIFNa-2b was similar to previous studies. Conclusions: PegIFNa-2b did not significantly improve MFS estimated by biopsy compared with observation; however, activity scores were significantly improved and MFS trended toward increased improvement with treatment durations >2.5 years. Both FibroTest and ActiTest were significantly improved during maintenance therapySalvado

Modelling cytomegalovirus replication patterns in the human host: factors important for pathogenesis

Human cytomegalovirus can cause a diverse range of diseases in different immunocompromised hosts. The pathogenic mechanisms underlying these diseases have not been fully elucidated, though the maximal viral load during infection is strongly correlated with the disease. However, concentrating on single viral load measures during infection ignores valuable information contained during the entire replication history up to the onset of disease. We use a statistical model that allows all viral load data sampled during infection to be analysed, and have applied it to four immunocompromised groups exhibiting five distinct cytomegalovirus-related diseases. The results show that for all diseases, peaks in viral load contribute less to disease progression than phases of low virus load with equal amount of viral turnover. The model accurately predicted the time of disease onset for fever, gastrointestinal disease and pneumonitis but not for hepatitis and retinitis, implying that other factors may be involved in the pathology of these diseases

Improved inflammatory activity with peginterferon alfa-2b maintenance therapy in non-cirrhotic prior non-responders: A randomized study

Therapeutic options for patients failing hepatitis C retreatment are limited. EPIC3 included a prospective trial assessing long-term peginterferon alfa-2b (PegIFNα-2b) maintenance therapy in patients with METAVIR fibrosis scores (MFS) of F2 or F3 who previously failed hepatitis C retreatment. Patients with F2/F3 MFS who failed retreatment were randomized to PegIFNα-2b (0.5μg/kg/week, n=270) or observation (n=270) for 36months. Blinded liver biopsies obtained before retreatment and after maintenance therapy were evaluated using MFS and activity scores, and confirmatory testing was performed using FibroTest and ActiTest. In total, 348 patients had paired biopsies: 192 patients had missing post-treatment biopsies and were considered as having no change in fibrosis/activity scores. In total, 16% of patients receiving PegIFNα-2b and 11% of observation patients had improvement in MFS (p=0.32). More PegIFNα-2b than observation patients had improvement in activity score (20% vs. 9%; p 2.5years, improvement in MFS or activity score was more common with PegIFNα-2b than observation (21% vs. 14%, p=0.08 and 26% vs. 10%, p <0.001). FibroTest and ActiTest evaluations indicated significant benefit associated with PegIFNα-2b in terms of reduced fibrosis progression and improved activity score. The safety profile of PegIFNα-2b was similar to previous studies. PegIFNα-2b did not significantly improve MFS estimated by biopsy compared with observation; however, activity scores were significantly improved and MFS trended toward increased improvement with treatment durations >2.5years. Both FibroTest and ActiTest were significantly improved during maintenance therapy

Refinement of Stopping Rules During Treatment of Hepatitis C Genotype 1 Infection With Boceprevir and Peginterferon/Ribavirin

In comparison with peginterferon/ribavirin alone, boceprevir with peginterferon/ribavirin significantly improves sustained virological response (SVR) rates in patients with chronic hepatitis C virus (HCV) genotype 1 infections, but treatment failure remains a significant problem. Using phase 3 trial databases, we sought to develop stopping rules for patients destined to fail boceprevir-based combination therapy in order to minimize drug toxicity, resistance, and costs in the face of ultimate futility. Exploratory post hoc analyses using data from the Serine Protease Inhibitor Therapy 2 (SPRINT-2) study (treatment-naive patients) and the Retreatment With HCV Serine Protease Inhibitor Boceprevir and Pegintron/Rebetol 2 (RESPOND-2) study (treatment-experienced patients) were undertaken to determine whether protocol-specified stopping rules (detectable HCV RNA at week 24 for SPRINT-2 and at week 12 for RESPOND-2) could be refined and harmonized. In SPRINT-2, a week 12 rule with an HCV RNA cutoff of 100 IU/mL would have discontinued therapy in 65 of 195 failures (sensitivity 5 33%) without sacrificing a single SVR among 475 successes (specificity 5 100%). Viral variants emerged after week 12 in 36 of the 49 evaluable patients (73%) who would have discontinued at week 12 using a 100 IU/mL stopping rule. In RESPOND-2, five of six patients with week 12 HCV RNA levels between the lower limit of detection (9.3 IU/mL) and the lower limit of quantification (25 IU/mL) who continued therapy despite the protocol-stipulated futility rule achieved SVR; one additional patient with a week 12 HCV RNA level of 148 IU/mL also continued therapy, had undetectable HCV RNA at week 16, and attained SVR. Conclusion: Although a stopping rule of detectable HCV RNA at week 12 would have forfeited some SVR cases, week 12 HCV RNA levels 100 IU/mL almost universally predicted a failure to achieve SVR in both treatment-naive and treatment-experienced patients. In boceprevir recipients, the combination of 2 stopping rules-an HCV RNA level 100 IU/mL at week 12 and detectable HCV RNA at week 24-maximized the early discontinuation of futile therapy and minimized premature treatment discontinuation. (HEPATOLOGY 2012;56:567-575) C ombination therapy with peginterferon alfa/ ribavirin (P/R) has been the standard approach to the management of chronic hepatitis C virus (HCV) infections for the last decade. Sustained virological response (SVR) rates of 54% to 56% were achieved in the pivotal trials of Abbreviations: HCV, hepatitis C virus; LLD, lower limit of detection; LLQ, lower limit of quantification; P/R, pegintron alfa/ribavirin; RESPOND-2, Retreatment With HCV Serine Protease Inhibitor Boceprevir and Pegintron/Rebetol 2; SPRINT-2, Serine Protease Inhibitor Therapy 2; SVR, sustained virological response. From th