A novel GFP reporter mouse reveals Mustn1 expression in adult regenerating skeletal muscle, activated satellite cells and differentiating myoblasts.

AIM: Mustn1 has been implicated in myofusion as well as skeletal muscle growth and repair; however, the exact role and spatio-temporal expression of Mustn1 have yet to be fully defined. METHODS: Transgenic mice were generated with a 1512-bp sequence of the Mustn1 promoter directing the expression of GFP (Mustn1(PRO) -GFP). These mice were used to investigate the spatio-temporal expression of Mustn1(PRO) -GFP during skeletal muscle development and adult skeletal muscle repair, as well as various phases of the satellite cell lifespan (i.e. quiescence, activation, proliferation, differentiation). RESULTS: Mustn1(PRO) -GFP expression was observed within somites at embryonic day 12 and developing skeletal muscles at embryonic day 15 and 18. While uninjured adult tibialis anterior muscle displayed no detectable Mustn1(PRO) -GFP expression, cardiotoxin injury robustly elevated Mustn1(PRO) -GFP expression at 3 days post-injury with decreasing levels observed at 5 days and minimal, focal expression seen at 10 days. The expression of Mustn1(PRO) -GFP at 3 days post-injury consistently overlaid with MyoD although the strongest expression of Mustn1(PRO) -GFP was noted in newly formed myotubes that were expressing minimal levels of MyoD. By 5 days post-injury, Mustn1(PRO) -GFP overlaid in all myotubes expressing myogenin although cells were present expressing Mustn1(PRO) -GFP alone. The expression patterns of Mustn1(PRO) -GFP in regenerating muscle preceded the expression of desmin throughout the regenerative time course consistent with Mustn1 being upstream of this myogenic protein. Further, quiescent satellite cells located on freshly isolated, single myofibers rarely expressed Mustn1(PRO) -GFP, but within 24 h of isolation, all activated satellite cells expressed Mustn1(PRO) -GFP. Expression of Mustn1(PRO) -GFP in primary myoblasts diminished with prolonged time in proliferation media. However, in response to serum withdrawal, the expression of Mustn1(PRO) -GFP increased during myofusion (day 2) followed by declining expression thereafter. CONCLUSION: Mustn1(PRO) -GFP is expressed in activated satellite cells and myoblasts but continued time in proliferation media diminished Mustn1(PRO) -GFP expression. However, myoblasts exposed to serum withdrawal increased Mustn1(PRO) -GFP expression consistent with its demonstrated role in myofusion. The in vivo expression pattern of Mustn1 observed in regenerating and developing skeletal muscle is consistent with its presence in satellite cells and its critical role in myofusion.

[Specific developmental disorders and the family--pathogenetic factors in children with behavioral disorders]. / Teilleistungsstörungen und Familie--pathogenetische Faktoren bei verhaltensauffälligen Kindern.

121 children aged 5;6 to 8;6 years referred to our center as out-patients because of various types of behavioral problems and showing distinct symptoms of minor neurological dysfunction were investigated with regard to family-related variables, specific developmental disorders, and the extent of the behavioral problems. A comparison of the groups with few and numerous behavioral problems showed a significant difference in the number of familial risk factors, but not in the degree of neurological and cognitive dysfunction. These results indicate the importance of child-independent familial factors, e.g. marital problems and psychosocial stress, in the pathogenesis of behavioral disturbances in children with minor neurological dysfunction. The resulting need for a family-oriented perspective in assessment and therapy is discussed.

["Better parenthood"--child rearing behavior of mothers with handicapped children and their evaluation by specialists]. / Die "bessere Elternschaft"--Erziehungshaltung von Müttern behinderter Kinder und deren Bewertung durch Fachleute.

Rejection, overprotectiveness and overindulgence are often found as educational attitudes in parents of handicapped children. The rehabilitation experts' own educational preferences were examined by questionnaire and confronted with those of the parents. The results suggest a interactional pattern of hidden struggle between experts and parents for being the "best parent".