Many studies have documented an association between chronic low back pain (LBP) and deficits in back muscle strength and endurance. The sub-optimal performance is believed to be the result of alterations in the size and structure of the muscle, although the long-standing issue of whether the observed changes precede or are a consequence of the pain remains unresolved. If consequent to the problem, and predominantly related to disuse of the muscles, then it may be expected that a relationship between muscle structure and symptom duration would exist. Lumbar paraspinal muscle samples were obtained from 59 chronic LBP patients using the percutaneous biopsy technique. The samples were subject to routine histochemical analysis for the examination of muscle fibre type characteristics and cytochemical architectural changes. In 55 of the patients, the gross cross-sectional areas of magnetic resonance images of the trunk muscles were also measured. Multivariate analysis showed that symptom duration was the strongest predictor of the individual proportions of the fast-fatigable type IIX fibres; with age and gender included in the model, nearly 30% of the variance in fibre type distribution could be accounted for. Duration of pain had no influence on fibre size. Gross muscle cross-sectional area correlated directly with lean body mass and inversely with age, but showed no relationship with symptom duration. Pathological changes in the internal fibre structure were more frequently encountered in older patients, and were independent of symptom duration. The results suggest that, over the long term, fibre type transformations rather than alterations in fibre size are the predominant changes to be found in the muscles of chronic LBP patients. The direction of change supports the results of many previous studies that have demonstrated corresponding differences in the fatigability of the muscles. There is a strong case for the early implementation of active measures to attempt to offset the development of these changes in back pain patients.

Parvalbumin (PV) is a high affinity Ca2+-binding protein found at high concentration in fastcontracting/relaxing skeletal muscle fibers of vertebrates. It has been proposed that PV acts in the process of muscle relaxation by facilitating Ca2+ transport from the myofibrils to the sarcoplasmic reticulum. However, on the basis of metal-binding kinetics of PV in vitro, this hypothesis has been challenged. To investigate the function of PV in skeletal muscle fibers, direct gene transfer was applied in normal and regenerating rat soleus muscles which do not synthesize detectable amounts of PV. Two weeks after in vivo transfection with PV cDNA, considerable levels of PV mRNA and protein were detected in normal muscle, and even higher amounts were detected in regenerating muscle. Twitch half-relaxation time was significantly shortened in a dose-dependent way in transfected muscles, while contraction time remained unaltered. The observed shortening of half-relaxation time is due to PV and its ability to bind Ca2, because a mutant protein lacking Caa2+-binding capacity did not promote any change in physiology. These results directly demonstrate the physiological function of PV as a relaxing factor in mammalian skeletal muscle.Skeletal muscle relaxation after a single twitch or a tetanic contraction is initiated by a reduction in sarcoplasmic Ca2+ concentration. Mainly, the efficiency of this processes is dictated by the following three consecutive steps of Ca2+ removal: (i) dissociation of Ca> from troponin C, (ii) translocation of Ca2+ to near the site of entry into the sarcoplasmic reticulum (SR), and (iii) uptake of Ca>2 into the SR by the Ca2+ pump.It is not known which of these mechanisms is rate limiting in slow-relaxing muscle fibers. The high-affinity Ca2+-binding protein parvalbumin (PV) has been shown to be highly concentrated in the sarcoplasm of fast-contracting/relaxing muscles of vertebrates (1, 2). PV binds two Ca2+ per mol with high affinity [-log of dissociation constant (pKd 7-8) in competition with Mg2+ (pKd 4-5)] (3, 4). It has been proposed that PV may facilitate Ca2+ translocation within the sarcoplasm (5-9).PV can deplete isolated myofibrils of Ca2+, and isolated SR can deplete PV of Ca2+ (5). Simulation studies indicate that Ca2+ exchange for Mg2+ can occur fast enough for PV to act as a relaxing factor in frog muscle (8). In addition, it was found that PV content and Ca2+-and Mg2+-dissociation rates correlate with changes in relaxation rate of frog muscle fibers at 0°C (10), and PV levels in skeletal muscles of mammals correlate positively with relaxation speed (9). However, no direct evidence for an involvement of PV in the relaxation process exists so far. Additionally, on the basis of kinetic measurements in vitro, it was argued that the Ca2+/Mg2+ exchange in PV is too slow to allow rapid removal of Ca2+ from the myofibrils after a single twitch (11, 12).The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "adve...

Following partial denervation motor units can increase (by self-reinnervation) as much as four to five times their normal size. To investigate the still unknown quantitative reinnervation capacity of a motor nerve in the case of foreign-reinnervation, in adult male rats the denervated sternomastoid muscle was either self-reinnervated by its original nerve or foreign-reinnervation by the omohyoid nerve, which had to reinnervate the three times the amount of muscle fibers and six times the amount of muscle mass. After survival times of 7, 8, 9, or 10 months, nerves and muscles were investigated histochemically and immunohistochemically. The omohyoid nerve could fully reinnervate the sternomastoid muscle, but at 7 and 8 months this muscle still revealed nearly the same proportions of IIA and IIB fibers as were seen in the self-reinnervated sternomastoid at all stages. However, in the following 2 months a shift of the fiber pattern toward that of the normal omohyoid was observed, as evidenced by a strong increase in type IIB fibers (from 24% to 62%), at the expense of type IIA fibers. These findings are in contrast to those after foreign (cross) reinnervation of leg muscles where the fiber transformation (according to the foreign motor input) occurs in parallel with the reinnervation process during the first 2-3 months. The delayed fiber transformation observed could be the consequence of the highly enlarged peripheral field of the omohyoid motoneuron pool or could merely reflect a general difference between limb and neck muscles.(ABSTRACT TRUNCATED AT 250 WORDS)

Considering the constant increase of medication costs in medical institutions we analysed in a Swiss municipal nursing home whether medication in geriatric long term patients can be reduced without compromising quality of life. To document these effects we applied two established questionnaires on different issues of quality of life; the interviews with the patients and with the nursing staff were performed as a pre-post-comparison of the 3-month intervention. The new geriatric medication concept allowed a decreased daily medication as well as a 23% reduction of the medication costs at an average. In comparison to a previous group of control this study showed no reduction in quality of life for nursing home residents but even a stabilisation yielding to an actual improvement of quality of life.

The aim of the present study was to assess health related characteristics and reasons for participation on the <>, second, to compare these variables with a representative Swiss Health Survey (SHS). Characteristics of the participants were collected cross-sectionally and afterwards compared with results of the SHS. Response rate was 74.6% (n = 206). Compared to the SHS population smoking rate and alcohol consumption were significantly lower and a doctor's visit within the last 12 months more frequent. Considerable differences in health related characteristics exist between our study and the SHS suggesting a self-selection of healthy people. Thus a potential health gain by this kind of medical prevention program is at least questionable.