Quantitative modelling of amyloidogenic processing and its influence by SORLA in Alzheimer's disease

The extent of proteolytic processing of the amyloid precursor protein (APP) into neurotoxic amyloid-β (Aβ) peptides is central to the pathology of Alzheimer's disease (AD). Accordingly, modifiers that increase Aβ production rates are risk factors in the sporadic form of AD. In a novel systems biology approach, we combined quantitative biochemical studies with mathematical modelling to establish a kinetic model of amyloidogenic processing, and to evaluate the influence by SORLA/SORL1, an inhibitor of APP processing and important genetic risk factor. Contrary to previous hypotheses, our studies demonstrate that secretases represent allosteric enzymes that require cooperativity by APP oligomerization for efficient processing. Cooperativity enables swift adaptive changes in secretase activity with even small alterations in APP concentration. We also show that SORLA prevents APP oligomerization both in cultured cells and in the brain in vivo, eliminating the preferred form of the substrate and causing secretases to switch to a less efficient non-allosteric mode of action. These data represent the first mathematical description of the contribution of genetic risk factors to AD substantiating the relevance of subtle changes in SORLA levels for amyloidogenic processing as proposed for patients carrying SORL1 risk alleles.

Long term administration of LMWH - pharmacodynamic parameters under therapeutic or prophylactic regimen of enoxaparin or tinzaparin in neurological rehabilitation patients

We investigated anti-FXa- and anti-FIIa-activity, thrombin generation (ETP), tissue factor pathway inhibitor (TFPI) - and D-dimer in patients exhibiting high bleeding risk in early neurological rehabilitation over 2 months in an observational study. Blood of 64 patients under LMWH administration due to therapeutic (cohort 1 [tinzaparin 90 IE/kg BID, N = 18] and 2 [enoxaparin 100 IE/kg BID; N = 15]) or prophylactic (cohort 3 [tinzaparin 4500 IE; N = 16] and 4 [enoxaparin 4000 IE; N = 15]) indication was drawn before and 4h after injection on day 7 (V1) and 2 months (follow up [V2]). Although the dose in cohort 1 and 2 was similar (median 7000 IE BID), a-FXa-activity was significantly larger under enoxaparin than under tinzaparin (e.g. median at V2: 0.70 IU/ml vs. 0.33 IU/ml). Also, prophylactic enoxaparin exhibited larger a-FXa-activity than tinzaparin (e.g. median at V2: 0.37 IU/ml vs. 0.22 IU/ml). The a-FXa/a-FIIa-ratio in plasma samples at 4h p.a. was about 4 (tinzaparin) and 8 (enoxaparin), respectively. No differences were seen for TFPI and ETP between cohort 1 and 2 or between cohort 3 and 4. D-dimer levels decreased significantly between V1 (e.g. cohort 4 median 1940 ng/ml) and V2 (median 652 ng/ml). Minimal bleeding events occurred in 6 patients (2 under tinzaparin, 4 under enoxaparin) and were associated with significantly higher anti-FXa-activity. In conclusion, although marked differences between tinzaparin and enoxaparin based on anti-FXa-activity were seen, markers of in vivo biological activity such as TFPI and D-dimer were not different. Furthermore, BID tinzaparin is a feasible option for therapeutic anticoagulation in patients with high bleeding risk.

Comparison of skeletal muscle strength between cardiac patients and age-matched healthy controls

The purpose of the present study was to compare muscular strength of knee extensors and arm flexor muscles of cardiac patients (n = 638) and healthy controls (n = 961) in different age groups. Isometric torques were measured in a sitting position with the elbow, hip, and knee flexed to 90(0). For statistical analysis, age groups were pooled in decades from the age of 30 to 90 years. Additionally, the influence of physical lifestyle prior to disease on muscular strength was obtained in the patients. For statistical analysis three-way ANOVA (factors age, gender, and physical activity level) was used.Both in patients and in controls a significant age-dependent decline in maximal torque could be observed for arm flexors and knee extensors. Maximal leg extensor muscle showed statistically significant differences between healthy controls and cardiac patients as well as between subgroups of patients: Physically inactive patients showed lowest torques (male: 148 +/- 18 Nm; female: 82 +/- 25 Nm) while highest values were measured in control subjects (male: 167 +/- 16 Nm; female: 93 +/- 17 Nm). In contrast, arm flexor muscles did not show any significant influence of health status or sports history.This qualitative difference between weight-bearing leg muscles and the muscle group of the upper extremity suggest that lower skeletal muscle strength in heart patients is mainly a consequence of selective disuse of leg muscles rather than any pathological skeletal muscle metabolism. Since a certain level of skeletal muscle strength is a prerequisite to cope with everyday activities, strength training is recommended as an important part of cardiac rehabilitation.

Age-related changes in marathon and half-marathon performances

We examined age-related changes in endurance performance of marathon and half-marathon finishers. A total of 405 515 running times were separated into groups based on age, sex, and distance. After exclusion of repetitive running times, 300 757 runners were analyzed by ANOVA (factors: age, sex). For each age group (six decades, 20-79 years), mean running times for all finishers, as well as top-ten performers, were assessed. As expected, age and sex had significant influence on running times. Female running times were about 10 % (marathon) and 13 % (half-marathon) above the corresponding times of their age-matched peers. The main finding is that in our sample of trained subjects significant age-related losses in endurance performance did not occur before the age of 50 years. Mean marathon and half-marathon times were virtually identical for the age groups from 20-49 years. Moreover, age-related performance decreases (p < 0.01) of the 50 - 69-year-old subjects were only in the range of 2.6 - 4.4 % per decade. These results suggest that the majority of older athletes are able to maintain a high degree of physical plasticity. The hypothesis that lifestyle factors have considerably stronger influences on functional capacity than the factor age is also supported by these findings from physically active and fit elderly.

Comparison of injection site pain and injection site reactions in relapsing-remitting multiple sclerosis patients treated with interferon beta-1a or 1b

This prospective, multicentre, international, observational, cohort study compared injection site pain (ISP) and injection site reactions (ISRS) between interferon beta-1b (IFNB-1b; Betaferon ®) 250 μg subcutaneously every other day and interferon beta-1a (IFNB-1a; Rebif®) 44 μg subcutaneously three times weekly in patients with relapsing-remitting MS. Patients started treatment within 3 months before recruitment and were on full dose of therapy at inclusion. Patients self-injected IFNB and self-assessed ISP for 15 consecutive injections immediately, 30 and 60 min after injection, using a visual analogue scale diary. Study staff assessed ISRS. Of 445 patients (valid cases), ~90% used autoinjectors. More patients were pain-free at all timepoints with IFNB-1b than with IFNB-1a (eg, 30 min: 42.6% versus 19.7%; P< 0.0001). The mean proportion of pain-free injections was greater for IFNB-1b (eg, 30 min: 79.0%) than for IFNB-1a (53.3%; P < 0.0001). The proportion of patients without ISRS was greater for IFNB-1b (second visit 51.8% versus 33.8%; P < 0.0001). Compared with IFNB-1a, more IFNB-1b patients either had no pain or their ISP had no influence on treatment satisfaction (76.9% versus 64.1%; P = 0.006). The impact on tolerability and patient acceptability of any new IFNB product formulations would, however, have to be evaluated in comparative studies. Multiple Sclerosis 2007; 13 : 1153—1160. http://msj.sagepub.com

Conditional and specific NF-kappaB blockade protects pancreatic beta cells from diabetogenic agents

Type 1 diabetes is characterized by the infiltration of inflammatory cells into pancreatic islets of Langerhans, followed by the selective and progressive destruction of insulin-secreting beta cells. Islet-infiltrating leukocytes secrete cytokines such as IL-1beta and IFN-gamma, which contribute to beta cell death. In vitro evidence suggests that cytokine-induced activation of the transcription factor NF-kappaB is an important component of the signal triggering beta cell apoptosis. To study the in vivo role of NF-kappaB in beta cell death, we generated a transgenic mouse line expressing a degradation-resistant NF-kappaB protein inhibitor (DeltaNIkappaBalpha), acting specifically in beta cells, in an inducible and reversible manner, by using the tet-on regulation system. In vitro, islets expressing the DeltaNIkappaBalpha protein were resistant to the deleterious effects of IL-1beta and IFN-gamma, as assessed by reduced NO production and beta-cell apoptosis. This effect was even more striking in vivo, where nearly complete protection against multiple low-dose streptozocin-induced diabetes was observed, with reduced intraislet lymphocytic infiltration. Our results show in vivo that beta cell-specific activation of NF-kappaB is a key event in the progressive loss of beta cells in diabetes. Inhibition of this process could be a potential effective strategy for beta-cell protection.

Escalating immunotherapy of multiple sclerosis--new aspects and practical application

Recent clinical studies in multiple sclerosis (MS) provide new data on the treatment of clinically isolated syndromes, on secondary progression, on direct comparison of immunomodulatory treatments and on dosing issues. All these studies have important implications for the optimized care of MS patients. The multiple sclerosis therapy consensus group (MSTCG) critically evaluated the available data and provides recommendations for the application of immunoprophylactic therapies. Initiation of treatment after the first relapse may be indicated if there is clear evidence on MRI for subclinical dissemination of disease. Recent trials show that the efficacy of interferon beta treatment is more likely if patients in the secondary progressive phase of the disease still have superimposed bouts or other indicators of inflammatory disease activity than without having them. There are now data available, which suggest a possible dose-effect relation for recombinant beta-interferons. These studies have to be interpreted with caution, as some potentially important issues in the design of these studies (e. g. maintenance of blinding in the clinical part of the study) were not adequately addressed. A meta-analysis of selected interferon trials has been published challenging the value of recombinant IFN beta in MS. The pitfalls of that report are discussed in the present review as are other issues relevant to treatment including the new definition of MS, the problem of treatment failure and the impact of cost-effectiveness analyses. The MSTCG panel recommends that the new diagnostic criteria proposed by McDonald et al. should be applied if immunoprophylactic treatment is being considered. The use of standardized clinical documentation is now generally proposed to facilitate the systematic evaluation of individual patients over time and to allow retrospective evaluations in different patient cohorts. This in turn may help in formulating recommendations for the application of innovative products to patients and to health care providers. Moreover, in long-term treated patients, secondary treatment failure should be identified by pre-planned follow-up examinations, and other treatment options should then be considered.

Normierung der Brief Repeatable Battery of Neuropsychological Tests (BRB-N) f�r den deutschsprachigen Raum

The Brief Repeatable Battery of Neuropsychological Tests (BRB-N) is a neuropsychological screening battery, often applied in multiple sclerosis (MS) patients. It is almost exclusively administered in trials and not in the daily practice routine because of the lack of normative values. Using a stepwise linear regression analysis, the dependence of test results on age, gender, and education of 241 healthy control subjects was investigated. Z-values of -1.68 or less were considered pathological. Based on the normative values, the proportions of cognitively impaired patients with relapsing-remitting MS (RRMS, n=43) and secondary progressive MS patients (SPMS, n=60) were calculated. The regression model explained 2.7-25.0% of the variance of test performances. Cognitive impairment occurred in 38% and in 47% of the RRMS and the SPMS groups, respectively. In both groups attention and concentration impairment was prominent, while in the SPMS group memory was also frequently affected. The proportion of cognitively impaired MS patients reflected the figures that could be found in the literature.