Folding and Aggregation of Designed Proteins

Studies of how protein fold have shown that the way protein clumps form in the test tube is similar to how proteins form the so-called ``amyloid'' deposits that are the pathological signal of a variety of diseases, among them the memory disorder Alzheimer's. Protein aggregation have traditionally been connected to either unfolded or native states. Inclusion body formation (disordered aggregation) has been assumed to arise from hydrophobic aggregation of the unfolded or denaturated states, while the amyloid fibrils (ordered aggregation) have been assumed to arise from native-like conformations in a process analogous to the polymerization of hemoglobin S. Making use of lattice-model simulations we find that both ordered and disordered aggregation arise from elementary structures which eventually build the folding nucleus of the heteropolymers, and takes place when some of the most strongly interacting amino acids establish their contacts leading to the formation of a specific subset of the native structure. These elementary structures can be viewed as the partially folded intermediates suggested to be involved in the aggregation of a number of proteins. These results have evolutionary implications, as the elementary structures forming the folding core of designed proteins contain the residues which are conserved among the members of homologous sequences.Comment: 10 pages, 2 colour ps figures and 1 b/w ps figur

Failure to Preserve β-Cell Function With Mycophenolate Mofetil and Daclizumab Combined Therapy in Patients With New- Onset Type 1 Diabetes

OBJECTIVE This trial tested whether mycophenolate mofetil (MMF) alone or with daclizumab (DZB) could arrest the loss of insulin-producing β-cells in subjects with new-onset type 1 diabetes. RESEARCH DESIGN AND METHODS A multi-center, randomized, placebo-controlled, double-masked trial was initiated by Type 1 Diabetes TrialNet at 13 sites in North America and Europe. Subjects diagnosed with type 1 diabetes and with sufficient C-peptide within 3 months of diagnosis were randomized to either MMF alone, MMF plus DZB, or placebo, and then followed for 2 years. The primary outcome was the geometric mean area under the curve (AUC) C-peptide from the 2-h mixed meal tolerance test. RESULTS One hundred and twenty-six subjects were randomized and treated during the trial. The geometric mean C-peptide AUC at 2 years was unaffected by MMF alone or MMF plus DZB versus placebo. Adverse events were more frequent in the active therapy groups relative to the control group, but not significantly. CONCLUSIONS Neither MMF alone nor MMF in combination with DZB had an effect on the loss of C-peptide in subjects with new-onset type 1 diabetes. Higher doses or more targeted immunotherapies may be needed to affect the autoimmune process

Gender differences in advanced heart failure: insights from the BEST study

OBJECTIVES: The goal of this study was to determine the influence of gender on baseline characteristics, response to treatment, and prognosis in patients with heart failure (HF) and impaired left ventricular ejection fraction (LVEF). BACKGROUND: Under-representation of women in HF clinical trials has limited our understanding of gender-related differences in patients with HF. METHODS: The impact of gender was assessed in the Beta-Blocker Evaluation of Survival Trial (BEST) which randomized 2,708 patients with New York Heart Association class III/IV and LVEF < or =0.35 to bucindolol versus placebo. Women (n = 593) were compared with men (n = 2,115). Mean follow-up period was two years. RESULTS: Significant differences in baseline clinical and laboratory characteristics were found. Women were younger, more likely to be black, had a higher prevalence of nonischemic etiology, higher right and left ventricular ejection fraction, higher heart rate, greater cardiothoracic ratio, higher prevalence of left bundle branch block, lower prevalence of atrial fibrillation, and lower plasma norepinephrine level. Ischemic etiology and measures of severity of HF were found to be predictors of prognosis in women and men. However, differences in the predictive values of various variables were noted; most notably, coronary artery disease and LVEF appear to be stronger predictors of prognosis in women. In the nonischemic patients, women had a significantly better survival rate compared with men. CONCLUSIONS: In HF patients with impaired LVEF, significant gender differences are present, and the prognostic predictive values of some variables vary in magnitude between women and men. The survival advantage of women is confined to patients with nonischemic etiology

Hormone replacement therapy is associated with improved survival in women with advanced heart failure

OBJECTIVES: We sought to determine whether hormone replacement therapy (HRT) is associated with an improved prognosis in women with advanced heart failure (HF) and systolic dysfunction. BACKGROUND: There are about two million postmenopausal women in the U.S. with HF. However, limited data are available to assess the effects of HRT on survival in this large group of patients. METHODS: A retrospective analysis of women age 50 years and over entered into the Beta-Blocker Evaluation of Survival Trial (BEST) was conducted using Cox regression analysis comparing survival in HRT users and non-users after correcting for baseline variables known to predict survival in women with HF and systolic dysfunction. RESULTS: In 493 women age 50 years and older, HRT was associated with a significant reduction in mortality-21% mortality in HRT users and 34% in non-users (p = 0.025). Multivariate analysis demonstrated a hazard ratio for mortality of 0.6 (95% confidence interval = 0.36 to 0.97) (p = 0.039) for HRT users. The benefits of HRT were noted only in women with a nonischemic etiology of HF (n = 237). CONCLUSIONS: Hormone replacement therapy is associated with a marked improvement in survival in postmenopausal women with advanced HF. A prospective, randomized trial of HRT should be performed in this large group of patients

Impact of protein-polymer interactions in the antimicrobial activity of lysozyme/poly(3,4-ethylenedioxythiophene) biocapacitors

Biocapacitors constructed by combining lysozyme (LYZ) and poly(3,4-ethylenedioxythiophene) (PEDOT) retained the bactericidal activity of the protein when this was encapsulated within the polymeric matrix but lost the antimicrobial behaviour when the LYZ was adsorbed onto the polymer. In this work we use atomistic Molecular Dynamics simulations to examine the influence of protein···polymer interactions in the bactericidal activity of LYZ-containing biocapacitors. Results show that the anisotropic forces exerted by oxidized PEDOT chains on the adsorbed protein induce small structural changes that locally affect at the active centre, breaking the intra-residue interactions associated with the antibacterial mechanism. Conversely, isotropic polymer···protein interactions in biocapacitors with encapsulated LYZ do not affect the stability of the active centre. These observations suggest that the strong repulsive or attractive forces between p-doped polymer chains and the positively or negatively charged LYZ residues, respectively, are the only ones responsible for the protein activity.Peer ReviewedPostprint (author's final draft

Fall in C-peptide during first 2 years from diagnosis: Evidence of at least two distinct phases from composite type 1 diabetes trialnet data.

Interpretation of clinical trials to alter the decline in β-cell function after diagnosis of type 1 diabetes depends on a robust understanding of the natural history of disease. Combining data from the Type 1 Diabetes TrialNet studies, we describe the natural history of β-cell function from shortly after diagnosis through 2 years post study randomization, assess the degree of variability between patients, and investigate factors that may be related to C-peptide preservation or loss. We found that 93% of individuals have detectable C-peptide 2 years from diagnosis. In 11% of subjects, there was no significant fall from baseline by 2 years. There was a biphasic decline in C-peptide; the C-peptide slope was −0.0245 pmol/mL/month (95% CI −0.0271 to −0.0215) through the first 12 months and −0.0079 (−0.0113 to −0.0050) from 12 to 24 months (P \u3c 0.001). This pattern of fall in C-peptide over time has implications for understanding trial results in which effects of therapy are most pronounced early and raises the possibility that there are time-dependent differences in pathophysiology. The robust data on the C-peptide obtained under clinical trial conditions should be used in planning and interpretation of clinical trials

Rituximab, B-lymphocyte depletion, and preservation of beta-cell function

BACKGROUND: The immunopathogenesis of type 1 diabetes mellitus is associated with T-lymphocyte autoimmunity. However, there is growing evidence that B lymphocytes play a role in many T-lymphocyte-mediated diseases. It is possible to achieve selective depletion of B lymphocytes with rituximab, an anti-CD20 monoclonal antibody. This phase 2 study evaluated the role of B-lymphocyte depletion in patients with type 1 diabetes. METHODS: We conducted a randomized, double-blind study in which 87 patients between 8 and 40 years of age who had newly diagnosed type 1 diabetes were assigned to receive infusions of rituximab or placebo on days 1, 8, 15, and 22 of the study. The primary outcome, assessed 1 year after the first infusion, was the geometric mean area under the curve (AUC) for the serum C-peptide level during the first 2 hours of a mixed-meal tolerance test. Secondary outcomes included safety and changes in the glycated hemoglobin level and insulin dose. RESULTS: At 1 year, the mean AUC for the level of C peptide was significantly higher in the rituximab group than in the placebo group. The rituximab group also had significantly lower levels of glycated hemoglobin and required less insulin. Between 3 months and 12 months, the rate of decline in C-peptide levels in the rituximab group was significantly less than that in the placebo group. CD19+ B lymphocytes were depleted in patients in the rituximab group, but levels increased to 69% of baseline values at 12 months. More patients in the rituximab group than in the placebo group had adverse events, mostly grade 1 or grade 2, after the first infusion. The reactions appeared to be minimal with subsequent infusions. There was no increase in infections or neutropenia with rituximab. CONCLUSIONS: A four-dose course of rituximab partially preserved beta-cell function over a period of 1 year in patients with type 1 diabetes. The finding that B lymphocytes contribute to the pathogenesis of type 1 diabetes may open a new pathway for exploration in the treatment of patients with this condition

Use of comprehensive recruitment strategies in the glycemia reduction approaches in diabetes: A comparative effectiveness study (GRADE) multi-center clinical trial

Background/Aims: We present and describe recruitment strategies implemented from 2013 to 2017 across 45 clinical sites in the United States, participating in the Glycemia Reduction Approaches in Diabetes: A Comparative Effectiveness Study, an unmasked, randomized controlled trial evaluating four glucose-lowering medications added to metformin in individuals with type 2 diabetes mellitus (duration of diabetes <10 years). We examined the yield of participants recruited through Electronic Health Records systems compared to traditional recruitment methods to leverage access to type 2 diabetes patients in primary care. Methods: Site selection criteria included availability of the study population, geographic representation, the ability to recruit and retain a diverse pool of participants including traditionally underrepresented groups, and prior site research experience in diabetes clinical trials. Recruitment initiatives were employed to support and monitor recruitment, such as creation of a Recruitment and Retention Committee, development of criteria for Electronic Health Record systems queries, conduct of remote site visits, development of a public screening website, and other central and local initiatives. Notably, the study supported a dedicated recruitment coordinator at each site to manage local recruitment and facilitate screening of potential participants identified by Electronic Health Record systems. Results: The study achieved the enrollment goal of 5000 participants, meeting its target with Black/African American (20%), Hispanic/Latino (18%), and age ≧60 years (42%) subgroups but not with women (36%). Recruitment required 1 year more than the 3 years originally planned. Sites included academic hospitals, integrated health systems, and Veterans Affairs Medical Centers. Participants were enrolled through Electronic Health Record queries (68%), physician referral (13%), traditional mail outreach (7%), TV, radio, flyers, and Internet (7%), and other strategies (5%). Early implementation of targeted Electronic Health Record queries yielded a greater number of eligible participants compared to other recruitment methods. Efforts over time increasingly emphasized engagement with primary care networks. Conclusion: Glycemia Reduction Approaches in Diabetes: A Comparative Effectiveness successfully recruited a diverse study population with relatively new onset of type 2 diabetes mellitus, relying to a large extent on the use of Electronic Health Record to screen potential participants. A comprehensive approach to recruitment with frequent monitoring was critical to meet the recruitment goal

Fall in C-Peptide During First 2 Years From Diagnosis

Interpretation of clinical trials to alter the decline in β-cell function after diagnosis of type 1 diabetes depends on a robust understanding of the natural history of disease. Combining data from the Type 1 Diabetes TrialNet studies, we describe the natural history of β-cell function from shortly after diagnosis through 2 years post study randomization, assess the degree of variability between patients, and investigate factors that may be related to C-peptide preservation or loss. We found that 93% of individuals have detectable C-peptide 2 years from diagnosis. In 11% of subjects, there was no significant fall from baseline by 2 years. There was a biphasic decline in C-peptide; the C-peptide slope was −0.0245 pmol/mL/month (95% CI −0.0271 to −0.0215) through the first 12 months and −0.0079 (−0.0113 to −0.0050) from 12 to 24 months (P < 0.001). This pattern of fall in C-peptide over time has implications for understanding trial results in which effects of therapy are most pronounced early and raises the possibility that there are time-dependent differences in pathophysiology. The robust data on the C-peptide obtained under clinical trial conditions should be used in planning and interpretation of clinical trials

Mapping Site-Specific Changes that Affect Stability of the NTerminal Domain of Calmodulin

Biophysical tools have been invaluable in formulating therapeutic proteins. These tools characterize protein stability rapidly in a variety of solution conditions, but in general, the techniques lack the ability to discern site-specific information to probe how solution environment acts to stabilize or destabilize the protein. NMR spectroscopy can provide site-specific information about subtle structural changes of a protein under different conditions, enabling one to assess the mechanism of protein stabilization. In this study, NMR was employed to detect structural perturbations at individual residues as a result of altering pH and ionic strength. The N-terminal domain of calmodulin (N-CaM) was used as a model system, and the 1H-15N heteronuclear single quantum coherence (HSQC) experiment was used to investigate effects of pH and ionic strength on individual residues. NMR analysis revealed that different solution conditions affect individual residues differently, even when the amino acid sequence and structure are highly similar. This study shows that addition of NMR to the formulation toolbox has the ability to extend understanding of the relationship between site-specific changes and overall protein stability