Establishing Fluorine-Containing Amino Acids as an Orthogonal Tool in Coiled Coil Assembly.

The α-helical coiled coil (CC) is one of the best-characterized folding motifs in the protein world. In this context, fluorinated amino acids have been shown to be capable of tuning the properties of CC assemblies, and especially fluorinated derivatives of aliphatic amino acids can significantly increase the stability of this folding motif when placed in the hydrophobic a and d positions. However, it has not been shown yet whether fluorinated amino acids, by means of rational design, can be used as an orthogonal tool to control CC assembly processes. In the current work, we approached this question by creating a combinatorial peptide library based on a VPE/VPK heteromeric CC system previously established and characterized in our group. This CC model allowed us to screen fluorinated amino acids for interaction with different potential binding partners in position a of the VPE/VPK model with a particular emphasis on studying the impact of stereochemistry within the side chain of α-branched aliphatic fluorinated amino acids on CC properties such as oligomerization state, thermodynamic stability, and orientation. 28 combinations of library members were characterized regarding structure, oligomerization, and thermal stability utilizing circular dichroism, size exclusion chromatography, and Förster resonance energy transfer measurements. This detailed approach showed that the stability and oligomerization state of the motif were not only dependent on the steric demand and the fluorination of corresponding amino acids but also on the stereochemistry within the side chain. The results were applied for a rational design of the fluorine-driven orthogonal assembly, and we could show that CC dimer formation occurred based on specific interactions between fluorinated amino acids. These results demonstrate the potential of fluorinated amino acids as an orthogonal tool besides classical electrostatic and hydrophobic interactions for the fine-tuning and direction of peptide-peptide interactions. Furthermore, within the space of fluorinated amino acids, we could demonstrate the specificity of interactions between differently fluorinated side chains.

Is risk-stratified breast cancer screening economically efficient in Germany?

OBJECTIVES: Risk stratification has so far been evaluated under the assumption that women fully adhere to screening recommendations. However, the participation in German cancer screening programs remains low at 54%. The question arises whether risk-stratified screening is economically efficient under the assumption that adherence is not perfect. METHOD: We have adapted a micro-simulation Markov model to the German context. Annual, biennial, and triennial routine screening are compared with five risk-adapted strategies using thresholds of relative risk to stratify screening frequencies. We used three outcome variables (mortality reduction, quality-adjusted life years, and false-positive results) under the assumption of full adherence vs. an adherence rate of 54%. Strategies are evaluated using efficiency frontiers and probabilistic sensitivity analysis (PSA). RESULTS: The reduced adherence rate affects both performance and cost; incremental cost-effectiveness ratios remain constant. The results of PSA show that risk-stratified screening strategies are more efficient than biennial routine screening under certain conditions. At any willingness-to-pay (WTP), there is a risk-stratified alternative with a higher likelihood of being the best choice. However, without explicit decision criteria and WTP, risk-stratified screening is not more efficient than biennial routine screening. Potential improvements in the adherence rates have significant health gains and budgetary implications. CONCLUSION: If the participation rate for mammographic screening is as low as in Germany, stratified screening is not clearly more efficient than routine screening but dependent on the WTP. A more promising design for future stratified strategies is the combination of risk stratification mechanisms with interventions to improve the low adherence in selected high-risk groups.

Feasibility of structured endurance training and Mediterranean diet in BRCA1 and BRCA2 mutation carriers - an interventional randomized controlled multicenter trial (LIBRE-1).

BACKGROUND: Women with pathogenic BRCA germline mutations have an increased risk for breast and ovarian cancer that seems to be modified by life-style factors. Though, randomized trials investigating the impact of lifestyle interventions on cancer prevention and prognosis in BRCA carriers are still missing. METHODS: We implemented a multicenter, prospective randomized controlled trial in BRCA1/2 patients, comparing a lifestyle intervention group (IG) with a control group (CG) with the primary aim to prove feasibility. Intervention comprised a structured, individualized endurance training alongside nutrition education based on the Mediterranean diet (MD) for 3 months, plus monthly group training and regular telephone contact during the subsequent 9 months. The CG attended one session on healthy nutrition and the benefits of physical activity. Primary endpoints were feasibility, acceptance and satisfaction over 12 months. Furthermore, effects on physical fitness, diet profile, body mass index (BMI), quality of life and perceived stress were investigated. RESULTS: Sixty-eight participants (mean age 41, mean BMI 23.2 kg/m2) were enrolled, of whom 55 (81%, 26 IG, 29 CG) completed 12 months. 73% (n = 26) participated in at least 70% of all intervention sessions. Predictors for drop-outs (19%; n = 13) or non-adherence (27%; n = 7) were not found. 73% rated the program highly and 80% would participate again. Severe adverse events did not occur. Positive effects in the IG compared to the CG were observed for secondary endpoints: BMI, MD eating pattern and stress levels. CONCLUSIONS: This lifestyle intervention was feasible, safe and well accepted. Positive results on eating habits, physical fitness and stress levels warrant a larger randomized trial. TRIAL REGISTRATION: The study has been retrospectively registered at ClinicalTrials.gov (reference: NCT02087592 ) on March 12, 2014. The first patient was included on February 24, 2014.

Smoking and physical inactivity increase cancer prevalence in BRCA-1 and BRCA-2 mutation carriers: results from a retrospective observational analysis.

BACKGROUND: The aim of this analysis in a pilot study population was to investigate whether we can verify seemingly harmful lifestyle factors such as nicotine and alcohol indulgence, obesity, and physical inactivity, as well as a low socioeconomic status for increased cancer prevalence in a cohort of BRCA 1 and 2 mutation carriers. METHODS: The analysis data are derived from 68 participants of the lifestyle intervention study LIBRE-1, a randomized, prospective trial that aimed to test the feasibility of a lifestyle modification in BRCA 1 and 2 mutation carriers. At study entry, factors such as medical history, lifestyle behavior, and socioeconomic status were retrospectively documented by interview and the current BMI was determined by clinical examination. The baseline measurements were compared within the cohort, and presented alongside reference values for the German population. RESULTS: Study participants indicating a higher physical activity during their adolescence showed a significantly lower cancer prevalence (p = 0.019). A significant difference in cancer occurrence was observed in those who smoked prior to the disease, and those who did not smoke (p < 0.001). Diseased mutation carriers tended to have a lower BMI compared to non-diseased mutation carriers (p = 0.079), whereas non-diseased revealed a significantly higher physical activity level than diseased mutation carriers (p = 0.046). DISCUSSION: The present data in this small cohort of 68 mutation carriers suggest that smoking and low physical activity during adolescence are risk factors for developing breast cancer in women with BRCA1 or BRCA2 mutation. Further data of the ongoing LIBRE 2 study are necessary to confirm these findings in a larger cohort of 600 mutation carriers.

Lifestyle intervention in BRCA1/2 mutation carriers: study protocol for a prospective, randomized, controlled clinical feasibility trial (LIBRE-1 study).

BACKGROUND: Women with highly penetrant BRCA mutations have a 55-60% lifetime risk for breast cancer and a 16-59% lifetime risk for ovarian cancer. However, penetrance differs interindividually, indicating that environmental and behavioral factors may modify this risk. These include lifestyle factors such as physical activity status, dietary habits, and body weight. The modification of penetrance by changing lifestyle factors has not thus far been investigated in a randomized trial in BRCA mutation carriers. METHODS: Therefore, we intend to enroll 60 BRCA1/2 mutation carriers in a pilot feasibility study (Lifestyle Intervention Study in Women with Hereditary Breast and Ovarian Cancer (LIBRE) pilot). This multi-center, prospective, controlled trial aims to randomize (1:1) participants into a (1) multi-factorial lifestyle intervention group (IG) versus (2) the control group with usual care (CG). The primary endpoint is feasibility and acceptance of a structured interdisciplinary lifestyle intervention program over 12 months (at least 70% of the patients to complete the 1-year intervention). Furthermore, the effects on physical fitness, BMI, quality of life, and stress coping capacity will be investigated. During the first 3 months, women in the IG will receive structured, individualized and mainly supervised endurance training of ≥18 MET*h/week (MET = metabolic equivalent task) and personal nutritional counseling based on the Mediterranean diet. During the subsequent 9 months, the IG will receive monthly group training sessions and regular telephone contacts for motivation, whereas the CG will only receive usual care (one general counseling on healthy nutrition and benefits of regular physical activity on health status). At randomization and subsequent time points (3, 6, 12 months), cardiopulmonary fitness will be assessed by spiroergometry and nutritional and psychological status by validated questionnaires. DISCUSSION: This pilot study will investigate the optimal strategy to improve physical fitness, nutritional habits, and psychological factors in women at high risk for developing breast or ovarian cancer. The results of this pilot feasibility study will be the basis for a larger prospective randomized trial including clinical events (LIBRE). TRIAL REGISTRATION: ClinicalTrials.gov, NCT02087592.

Effects of lifestyle intervention in BRCA1/2 mutation carriers on nutrition, BMI, and physical fitness (LIBRE study): study protocol for a randomized controlled trial.

BACKGROUND: Women with highly penetrant BRCA mutations have a 55-60 % lifetime risk for breast cancer and a 16-59 % lifetime risk of developing ovarian cancer. However, penetrance differs interindividually, indicating that environmental and behavioral factors may modify this risk. It is well documented that the risk for sporadic breast cancer disease can be modified by changing lifestyle factors that primarily include physical activity, dietary habits, and body weight. It can thus be hypothesized that the modification of these lifestyle factors may also influence the incidence and progression of cancer in BRCA mutation carriers. METHODS/DESIGN: This multicenter, interdisciplinary, prospective, two-armed, randomized (1:1) controlled trial aims to enroll a minimum of 600 BRCA1 and BRCA2 mutation carriers to partake in either a lifestyle intervention or usual care. The study primarily aims to demonstrate an improvement of nutritional behavior (adherence to the Mediterranean diet), body mass index, and physical fitness. Furthermore, the effects on quality of life, stress coping capacity, breast cancer incidence, and mortality will be investigated. The intervention group (IG) will receive a structured lifestyle intervention over 12 months, whereas the control group (CG) will only receive information regarding a healthy lifestyle. During the first 3 months, women in the IG will receive structured, individualized, and mainly supervised endurance training with a minimum of 18 MET-h physical activity per week and nutrition education based on the Mediterranean diet. Over the following 9 months, IG monthly group training sessions and regular telephone contacts will motivate study participants. The CG will receive one general training session about healthy nutrition in accordance with the recommendations of the German Society of Nutrition (standard of care in Germany) and the benefits of regular physical activity on health status. At randomization and subsequent time points (3 and 12 months), cardiopulmonary fitness will be assessed by spiroergometry, and nutritional and psychological status will be assessed by validated questionnaires, interviews, and clinical examinations. DISCUSSION: As data on the role of lifestyle intervention in women with a hereditary risk for breast and ovarian cancer are currently lacking, this study will be of major importance from a scientific, as well as a practical advice viewpoint. It will investigate the optimal strategy to improve physical fitness, nutritional status, and psychological factors such as quality of life, perceived stress, optimism, as well as incidence and outcome of cancer in this selected group of women at high risk. If the study indicates a positive long-term outcome, a structured lifestyle intervention program could be added to health care prevention strategies for BRCA1 and BRCA2 mutation carriers. TRIAL REGISTRATION: ClinicalTrials.gov: NCT02516540 . Registered on 22 July 2015.

Autologous adult rodent neural progenitor cell transplantation represents a feasible strategy to promote structural repair in the chronically injured spinal cord.

Adult neural progenitor cells (NPCs) represent an attractive source for cell-based regenerative strategies in CNS disease. In animal models of spinal cord injury, syngenic adult NPCs, which were isolated from pooled post-mortem CNS tissue and co-transplanted together with fibroblasts, have been shown to promote substantial structural repair. The autologous transplantation of adult NPCs represents a major advantage compared with other sources of neural stem/progenitor cells. However, the feasibility of autologous NPC generation from a single biopsy in a relevant preclinical CNS disease model has yet to be demonstrated. To investigate this matter, adult Wistar rats underwent a cervical spinal cord lesion, which was followed by a minimal subventricular zone aspiration biopsy 2 days later. NPCs were isolated and propagated separately for each animal for the following 8 weeks. Thereafter, they were co-transplanted with simultaneously harvested skin fibroblasts in an autologous fashion into the cervical spinal cord lesion site. A total of 4 weeks later, graft survival, tissue replacement and axonal regeneration were assessed histologically. Animals receiving either allogenic NPCs combined with fibroblasts or autologous pure fibroblast grafts served as control groups. Within 8 weeks after the biopsy more than 3 million NPCs could be generated from a single aspiration biopsy, which displayed a differentiation pattern indistinguishable from syngenic NPC grafts. NPCs within autologous co-grafts readily survived, replaced cystic lesion defects completely and differentiated exclusively into glial phenotypes, thus paralleling previous findings with syngenic NPCs. The delayed transplantation 8 weeks after the spinal cord lesion elicited substantial axonal regeneration. These findings demonstrate that the therapeutic strategy to induce structural repair by transplanting adult autologous NPCs, after the successful propagation from a small brain biopsy into an acute CNS disease model, such as spinal cord injury, is feasible at the preclinical level.

Adult neural progenitor cells provide a permissive guiding substrate for corticospinal axon growth following spinal cord injury.

Adult neural progenitor cells (NPC) are an attractive source for cell transplantation and neural tissue replacement after central nervous system (CNS) injury. Following transplantation of NPC cell suspensions into the acutely injured rat spinal cord, NPC survive; however, they migrate away from the lesion site and are unable to replace the injury-induced lesion cavity. In the present study we examined (i) whether NPC can be retained within the lesion site after co-transplantation with primary fibroblasts, and (ii) whether NPC promote axonal regeneration following spinal cord injury. Co-cultivation of NPC with fibroblasts demonstrated that NPC adhere to fibroblasts and the extracellular matrix produced by fibroblasts. In the presence of fibroblasts, the differentiation pattern of co-cultivated NPC was shifted towards glial differentiation. Three weeks after transplantation of adult spinal-cord-derived NPC with primary fibroblasts as mixed cell suspensions into the acutely injured cervical spinal cord in adult rats, the lesion cavity was completely replaced. NPC survived throughout the graft and differentiated exclusively into glial cells. Quantification of neurofilament-labeled axons and anterogradely labeled corticospinal axons indicated that NPC co-grafted with fibroblasts significantly enhanced axonal regeneration. Both neurofilament-labeled axons and corticospinal axons aligned longitudinally along GFAP-expressing NPC-derived cells, which displayed a bipolar morphology reminiscent of immature astroglia. Thus, grafted astroglial differentiated NPC promote axon regrowth following spinal cord injury by means of cellular guidance.

Salvage therapy in patients with glioblastoma: is there any benefit?

BACKGROUND: Survival after first-line therapy is poor for patients with glioblastoma. The role of second-line treatment for recurrent disease is controversial. The authors studied the outcome in a subset of patients with glioblastoma who were selected for an aggressive reintervention strategy at the time of progression. Their objectives were to improve patients' overall survival with sustained quality of life and to make comparisons with overall survival in unselected patients. METHODS: Overall, 168 patients were eligible for retrospective analysis. Ninety patients received specific therapy for disease recurrence (reintervention group) by specific criteria. RESULTS: In the reintervention group, promising median overall survival (mOS) results after diagnosis (61.5 weeks) and progression (33 weeks) were obtained. The progression-free survival (PFS) rate at 12 months and the overall survival rate were superior in the reintervention group (71% at 12 months and 32% at 24 months) compared with the total cohort (45% and 20%, respectively) and the standard group (15% and 5%, respectively). A matched-pair analysis (n = 46 in each group), with an mOS period of 65.5 versus 28.5 weeks, confirmed these data. Quality of life was stable or slightly improved during reinterventions in a subset of patients treated within clinical studies. CONCLUSIONS: The majority of patients in the current series were treated with a reintervention strategy, which had an impact on PFS and mOS. A second resection, focal radiotherapy (in selected cases), and additional chemotherapeutic regimens should be considered for patients with recurrent glioblastoma.