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R Harjula

Publications and source records attributed to R Harjula.

7 recordsLinked to original sources
PubMed2001

Expression of L-type calcium channels associated with postnatal development of skeletal muscle function in mouse.

Several factors have an influence on the improvement of muscle activity and motor co-ordination of mammals during post-natal development. One of them is voltage sensitive L-type calcium channel function. In striated muscles of adult mammals these channels are located in T-tubule membranes thus linking the on-coming action potential to the molecular process of muscle contraction. The postnatal development of L-type calcium channels is therefore critical not only for contraction but also for all subsequent motor learning. We used high affinity enantiomer of dihydropyridine labelled with a fluorophore in order to show the relative amount of L-type calcium channels by histofluorescence in tissue. We found by qualitative microscopical analysis that the amount of L-type calcium channels increased during the postnatal development in the mouse skeletal muscle (m. rectus femoris and m. gastrocnemius). We also noted variation between different fibre types in the increase of the amount of L-type calcium channels, as judged by the intensity of histofluorescence. We showed by histochemical staining and statistical analysis that the high density of L-type calcium channels in adult muscles is correlated with fast oxidative glycolytic fibre type of striated muscles rather than slow oxidative or fast glycolytic fibres. Based on this finding we propose that the development of L-type calcium channels can be considered as one of the factors determining the different physiological properties of fibre types.

Aging↗
PubMed2000

Local cutaneous water barrier in cold- and heat-acclimated pigeons (Columba livia) in relation to cutaneous water evaporation.

The thermoregulatory function of the skin differs in adult cold-acclimated and heat-acclimated rock pigeons (Columba livia). In general, the cutaneous evaporative cooling mechanism is not activated by appropriate stimuli in cold-acclimated pigeons in contrast to heat-acclimated pigeons. We studied with electron microscopy whether the differences in the function of the skin are reflected in the structure of the epidermal water barrier of these two extreme acclimation states. The epidermis of cold-acclimated pigeons is attenuated, and the underlying dermis lacks any intimate vascularization. Both the extracellular and the intracellular domains in the stratum corneum contain organized lamellar lipids. At the stratum transitivum-stratum corneum interface, multigranular body secretion is indicated by the highly convoluted cell membranes and membraneous sacculae enclosing the multigranular bodies. Alternatively, multigranular bodies retain in the corneocytes, and the lipoid material originated from them is reprocessed to broad lamellae. The keratohyalin (KH) granules are spotlike and oriented as cortical bands beneath the plasma membrane. In heat-acclimated pigeons, the epidermis displays modified patches side by side with basic structural type of epidermis. The modified areas are characterized by hypertrophy and abundance of dermal capillaries adjacent to the hypertrophied patch. No lamellar lipids are discerned in the dilated extracellular space. The structure of multigranular bodies is abnormal, and the numbers of lipid droplets in the outer viable epidermis and stratum corneum are decreased. The transitional cells contain stellate KH granules, which form a network throughout the cell. It is concluded that cold-acclimated pigeons have a lamellar, extracellular water barrier, the cutaneous water evaporation is minimized, and heat is stored in the body core. Acclimation to heat leads to formation of structurally heterogeneous skin. The structurally modified skin patches show disruption of the barrier-forming machinery in the multigranular bodies and marked reorganization of fibrillar proteins and electron-dense KH masses in the transitional layer. Thus water barrier adjustments in cold- and heat-acclimated pigeons manifest the dynamic function of avian skin as a thermoregulatory organ.

Acclimatization↗
PubMed1991

Aerobic capacity among chronic low-back-pain patients.

The role of aerobic capacity (maximal oxygen uptake, VO2max) in connection with chronic low-back pain was assessed in a study mainly designed to evaluate the outcome of inpatient and outpatient treatment of low-back pain. A total of 245 subjects (ages 35-54 years, 71% men)--81 inpatients, 88 outpatients, and 76 controls--who had chronic low-back pain but who were still working, performed maximal graded bicycle ergometer tests four times during the follow-up of 30 months. In every group the estimated VO2max was on the level of the reference values of healthy persons. There were no significant changes in the VO2max in any of the intervention groups during the follow-up period. The correlation analyses showed no connection between aerobic capacity and pain or disability caused by chronic low-back pain. Among several components of physical fitness, aerobic capacity had no predictive value in the course of low-back pain.

Adult↗
PubMed1987

Lung function in relation to thoracic spinal mobility and kyphosis.

Mobility and kyphosis of the thoracic spine were correlated with lung function in 185 men and 87 women not suffering from respiratory disease. Curvatures of the spine were measured goniometrically with inclinometers and a compass, and lung function by spirometry. Vital capacity and forced expiratory volume in 1 sec had significant positive correlations only with forward and lateral flexion. The strongest correlations were with forward flexion (r = 0.16 to 0.24, p less than 0.05). The results and possible advantages of mobilizing the thoracic spine in pathological conditions of the lungs and the spine are discussed.

Adult↗