Succinate dehydrogenase inhibitors: in silico flux analysis and in vivo metabolomics investigations show no severe metabolic consequences for rats and humans.

Succinate dehydrogenase complex II inhibitors (SDHIs) are widely used fungicides since the 1960s. Recently, based on published in vitro cell viability data, potential health effects via disruption of the mitochondrial respiratory chain and tricarboxylic acid cycle have been postulated in mammalian species. As primary metabolic impact of SDH inhibition, an increase in succinate, and compensatory ATP production via glycolysis resulting in excess lactate levels was hypothesized. To investigate these hypotheses, genome-scale metabolic models of Rattus norvegicus and Homo sapiens were used for an in silico analysis of mammalian metabolism. Moreover, plasma samples from 28-day studies with the SDHIs boscalid and fluxapyroxad were subjected to metabolome analyses, to assess in vivo metabolite changes induced by SDHIs. The outcome of in silico analyses indicated that mammalian metabolic networks are robust and able to compensate different types of metabolic perturbation, e.g., partial or complete SDH inhibition. Additionally, the in silico comparison of rat and human responses suggested no noticeable differences between both species, evidencing that the rat is an appropriate testing organism for toxicity of SDHIs. Since no succinate or lactate accumulation were found in rats, such an accumulation is also not expected in humans as a result of SDHI exposure.

[Age-related activation of the muscles during upright standing in patients with haemophilia]. / Altersabhängige Ansteuerung der Muskulatur im Stand bei Patienten mit Hämophilie.

Thehaemophilicarthropathyaffects thefunction of theknee joint muscles. The aim of thisstudywas to investigatethe myoelectrical signal ofknee jointmusclesin different agestages during upright standing. Surface EMG (SEMG) amplitudes of quadriceps, hamstrings and gastrocnemii were measured in 191 patients with severe haemophilia A (n=164) and B (n=27) while standing on an even surface. After an age-based classification of patients into the subgroups H(A): 17-29 (n = 37), H(B): 30-39 (n = 50), HC: 40-49 (n = 61), H(D): 50-70 in years (n = 43) the clinical WFH score for the ankle and knee joint was determined. To normalize the SEMG values amplitude ratios (percentage of cumulated activity) were calculated with respect to the specific limb. With increasing age, the patient showed descriptively a deterioration of the joint situation. The extensors of the knee joint reached significantly higher absolute and percentage levels in the muscle activity with increasing age (p < 0.05). The absolute amplitude values of the Mm. gastrocnemii showed no differences in the age groups while the relative levels were decreased. The present study shows that patients with increasing age and degree of haemophilic arthropathy develop a modified control strategy during upright standing, in the form of a shift from the plantar flexors to the extensors of the knee joint.

Impact of joint status on contraction steadiness of m. quadriceps femoris in people with severe haemophilia.

Impaired contraction steadiness of lower limb muscles affects functional performance and may increase injury risk. We hypothesize that haemophilic arthropathy of the knee and the strength status of quadriceps are relevant factors which compromise a steady contraction. This study addresses the questions if impaired steadiness of the quadriceps is verifiable in people with haemophilia (PWH) and whether a connection between the status of the knee joint and quadriceps strength exists. A total of 157 PWH and 85 controls (C) performed a strength test with a knee extensor device to evaluate their bilateral and unilateral maximal quadriceps strength and steadiness. Isometric steadiness was measured by the coefficient of variation of maximum peak torque (CV-MVIC in %). For classification of the knee joint status the World Federation of Haemophilia (WFH) score was used. Lower steadiness (higher CV values) was found in PWH compared with C during bilateral [PWH vs. C; 0.63 (0.36/1.13) vs. 0.35 (0.15/0.72), median (Q25/Q75) P < 0.001] and unilateral trials [left leg: 0.70 (0.32/1.64) vs. 0.50 (0.23/1.04), P < 0.05; right leg: 0.68 (0.29/1.51) vs. 0.39 (0.18/0.68), P < 0.001]. PWH with a WFH score difference (≥1) between their extremities showed a less steady contraction in the more affected extremity (P < 0.05). More unsteady contractions have also been found in extremities with lower quadriceps strength compared with the contralateral stronger extremities (P < 0.001), whereby the weaker extremities were associated with a worse joint status (P < 0.001). The results of this study verify an impaired ability to realize a steady contraction of quadriceps in PWH and the influence of joint damage and strength on its manifestation.

[Development and evaluation of a dance-based exercise therapy for patients with haemophilia]. / Entwicklung und Evaluierung einer tanzbasierten Bewegungstherapie für Patienten mit Hämophilie.

UNLABELLED: So far, the use of methods derived from creative arts has not been considered in the haemophilia treatment. The AIM was to investigate the expectations for a dance-based exercise therapy for patients with haemophilia and the extent of its acceptance. PATIENTS, METHOD: The one-hour dance-based exercise therapy was offered to 30 haemophilia patients (HI30) (49 ± 11, 30-67 years). For the evaluation of expectations, questionnaires were created and filled out by participants before and after the intervention. Additionally, 19 haemophilia patients (HF) and 20 controls without haemophilia (KF) who did not participate in the intervention were also questioned. The RESULTS show that haemophilia patients have more experience in dance than controls (HI30:62%, HF:74%, KF:45%). In contrast, the proportion of those who are currently dancing is higher in controls without haemophilia (HI30: 17%, HF: 10%, KF:26%). The termination of dance activity in patients with haemophilia who were part of the intervention was mainly due to pain (HI30: 40%, HF: 29%, KF: 0%), whereby controls without intervention terminated the dance activity mainly due to lack of time (HI30: 30%, HF: 57%, KF: 56%). Ultimately, 24 out of 30 patients with haemophilia (HI24) completed the intervention. All HI24 met their expectations. 38% felt limited by haemophilia while carrying out the exercises. The majority of the participants were able to follow the exercises well (96%) and were did not overstrain physically (92%) nor mentally (87%), also 79% did not have pain. 23 of HI24 (96%) can envision a continuation of the dance-based exercise therapy. CONCLUSION: The experience with the dance-based exercise therapy was predominantly positive. It represents an alternative sports therapy programme for patients with haemophilia. Further studies are needed in order to make statements concerning the long-term use of such training.

Quadriceps strength, inter-extremity difference (IED) and joint status in adult persons with severe haemophilia in different age stages.

Quadriceps weakness seems to be a hallmark in adult persons with severe haemophilia (PWH). The purpose of this study was to compare PWH and non-haemophilic controls in different age stages with reference to joint status and quadriceps strength. Further aims were to examine the extent of strength-specific inter-extremity-difference (IED) and the prevalence of abnormal IED (AIED). A total of 106 adults with severe haemophilia (H) and 80 controls (C) had undergone an orthopaedic examination for classification of knee and ankle status using the WFH score. Quadriceps strength was evaluated unilaterally as well as bilaterally with a knee extensor device. Each group was divided into four age-related subgroups (HA/CA: 18-29, HB/CB: 30-39, HC/CC: 40-49, HD/CD: 50-70; in years). H presented a worse knee and ankle status than C indicated by higher WFH scores (P < 0.01). Regarding the age-matched subgroups only HB showed higher knee scores than CB (P < 0.05). The ankles were clinically more affected in HB-HD compared with those in age-matched controls (P < 0.05). H showed lower quadriceps strength than C (P < 0.05). In addition, all subgroups of H presented lower strength (HA: 10-17, HB: 19-23, HC: 35-36, HD: 53-61; in%, P < 0.05). IED was higher in H than in C [H: 12.0 (5.3/32.2) vs. C: 7.1 (2.9/10.9); Median (quartiles) in%, P < 0.001] and increased with age in H. We discovered an AIED in 35% of H. These findings highlight the importance for the early implementation of preventive and rehabilitative muscle training programmes in the comprehensive treatment of PWH.

Recovery from 6 weeks of repeated strain injury to rat soleus muscles.

Recovery from chronic strain injury (50 strains daily, five times weekly for 6 weeks to hyperactive soleus muscles) was followed for 3 months in female rats after cessation of chronic hyperactivity induced by pretreatment of the plantar flexor muscles with tetanus toxin. After 6 weeks of repeated strains, muscle mass decreased by 62%, myofiber areas were reduced by 87%, and noncontractile tissue expanded dramatically by 222%. Collagen content increased by almost ninefold (control 40 +/- 3 microg/mg, chronic injury 392 +/- 53 microg/mg), whereas the molar ratio of collagen (pyridinoline) crosslinks to collagen remained the same (control 0.20 +/- 0.01, chronic injury 0.16 +/- 0.01). After 3 months of ambulation, muscle mass returned to normal but myofiber areas remained smaller by 21%, noncontractile tissue was still markedly elevated by 18% with increased collagen content (107 +/- 15 microg/mg), and the molar ratio of crosslinks to collagen increased by 75% during recovery. Thus, rat soleus muscles recovered very slowly and incompletely from chronic strain injuries that produced muscle fibrosis, highlighting the necessity of devising preventative strategies for repeated strain injuries.