Lumbar back muscle activity in relation to trunk movements during locomotion in man

The function of lumbar back muscles was studied by relating their activity patterns to trunk movements in 7 healthy adult males during normal walking (1.0-2.5 m/s) and running (2.0-7.0 m/s) on a treadmill. The movements of the trunk in the sagittal and frontal planes were recorded with a Selspot optoelectronic system using infrared light emitting diodes as markers. The electromyographic (EMG) activity from the two main portions of the lumbar erector spinae muscles (Multifidus and Longissimus) was recorded bilaterally with intramuscular wire electrodes. The angular displacements of the trunk showed regular oscillations, but their shape, magnitude and relation to the step cycle were different in the two planes (sagittal and frontal) and varied with speed and mode of progression. The EMG pattern in both muscles showed a bilateral cocontraction with two main bursts of activity per step cycle starting just before each foot was placed on the ground. Relating the EMG to the movements of the trunk indicated that the main function of the lumbar erector spinae muscles is to restrict excessive trunk movements. During walking this restricting action is most evident for movements in the frontal plane, whereas in running the lumbar back muscles mainly control the movements in the sagittal plane.

Effects of nicotine on endocytosis and intracellular degradation of horseradish peroxidase in cultivated mouse peritoneal macrophages

Thioglycollate-elicited mouse peritoneal macrophages were cultivated in vitro in control medium or medium containing nicotine (1 nM-1 microM). The drug caused a moderate lysosomal vacuolation and formation of vesicles with a dense core or ring. Furthermore, it partially inhibited uptake and intracellular degradation of horseradish peroxidase without affecting the specific activities of the lysosomal enzymes beta-glucuronidase and beta-N-acetylglucosaminidase in lysates of the cells. A slight inhibitory effect on the phagocytosis of latex beads was also noted. Since nicotine was used in concentrations of the same magnitude that may be obtained in the blood after smoking one cigarette, it seems worthwhile to further explore these findings in relation to the medical risks of smoking.

Fine structure of arterial smooth muscle cells cultured in the presence of whole blood serum or plasma-derived serum

Normal diploid cells require serum to proliferate in culture. Platelet-derived growth factor has been identified as the main serum component responsible for this effect. Here, smooth muscle cells were isolated enzymatically from the aorta of 5-day-old rats and cultured in the presence of 10% whole blood serum (WBS) or plasma-derived serum (PDS), i.e. with or without platelet factor, and studied by transmission electron microscopy. The cells proliferated actively in WBS-medium but remained quiescent in PDS-medium. Fine structurally, cells from WBS-cultures demonstrated numerous mitochondria, an extensive rough endoplasmic reticulum (RER), a large Golgi complex, a few lysosomes, and microfilaments arranged in parallel bundles. After transfer to PDS-medium, the RER- and Golgi cisternae were markedly dilated and the number of membrane-associated ribosomes decreased. Segregation of fragments of cytoplasm within autophagosomes was frequently observed and the number of lysosomes increased. Lipid droplets were more abundant and often gathered in the Golgi area. Moreover, the cells had become more irregular in shape and showed many bleb-like processes at their surface. Microfilament bundles had also become more prominent and crossed each other in different directions. These observations show that the removal of platelet factor from the medium clearly modifies the fine structure of cultured smooth muscle cells. The findings are in good agreement with the concept that platelet factor not only supports the proliferation of cultured cells but also stimulates their secretory activity.

Preoperative embolization of renal tumours using balloon catheters

Preoperative embolization was used in a series of 13 patients for reducing the bleeding during operation of even very large renal carcinomas. During and after embolization pain occurred which necessitated treatment. Balloon catheter embolization was used which excludes the risk of reflux of embolizing material to the aorta. It caused none or only minor injury to the renal arterial wall. No serious complication occurred.

Electron microscopic and cytochemical studies of rat aorta. Intracellular vesicles containing elastin- and collagen-like material

Small, rounded vesicles with a dense core of amorphous material were observed in all cell types in the young rat aorta, that is, endothelial cells, smooth muscle cells and fibroblasts. They were particularly numerous in the Golgi complex but were also found in the cell periphery. The content of the vesicles had staining characteristics identical to those of elastin. Material of the same type was also found in cisternae on the maturing side of the dictyosomes and in vesicles budding from them. Reaction product for thiamine pyrophosphatase was present in both these structures, indicating that the Golgi complex is responsible for the formation of the dense-cored vesicles. This was further supported by the absence of reaction product for acid phosphatase in the cisternae and in the vesicles. Moreover, no uptake of exogenous markers was noted in the latter. On the basis of these findings it is suggested that the dense-cored vesicles have a secretory function and contain precursors of elastin. Elongated vesicles or profiles containing collagen fibrils were observed in smooth muscle cells and fibroblasts. In the cell periphery, these vesicles were often found to communicate with the extracellular space. Further inside the cells, they showed a close spatial relationship to the Golgi complex. Neither thiamine pyrophosphatase nor acid phosphatase activity was demonstrated in the elongated vesicles. Like the plasma membrane, their limiting membrane was positively stained for alkaline phosphatase. On the basis of these findings and the absence of uptake of exogenous markers in them, it is suggested that the elongated vesicles represent a means for collagen secretion in the growing aortic wall. The Golgi complex is believed to be involved in the transfer of collagen to these vesicles.

Intra-abdominal pressure changes during natural movements in man

The weight of the upper part of the trunk is partially transmitted to the pelvis via the vertebral column. If the muscle walls around the abdominal cavity are contracted, a high pressure can be generated within the cavity (greater than 200 mmHg). The abdominal space can them transmit part of weight to, e.g., the upper part of the body, Intra-abdominal pressure recordings have been performed during locomotion and other natural movements with intragastric pressure recordings. With each step, there is a phasic variation in pressure, with its peak coinciding with that of the peak vertical force exerted by the leg against the ground. The peak values increase progressively with the speed of walking/running up to a mean of 38 mmHg and with trough values of 16 mmHg. The phasic variations with each step is due to a phasic activation of the abdominal muscles, with an EMG activity starting 50 ms or more before foot contact. If an extra load is put on the back, the posture changes and at the highest speed of running the pressure values are significantly higher than without this additional load. After a jump down from a moderate height of 0.4 m, the average increase is 89 mmHg and can often exceed 100 mmHg. These pressure changes are large and will presumably act to unload the spine under the prevailing biomechanical conditions and, in addition, there will no doubt be an effect on the circulatory system.

Fatigue and EMG of repeated fast voluntary contractions in man

A fatigue test consisting of repeated fast maximal contractions of the left quadriceps muscle in an isokinetic apparatus was performed by 12 healthy male subjects (19-25 yrs). EMG signals recorded from the surface of the left vastus lateralis muscle, from which also biopsies were obtained for muscle fibre classification. Only minor changes were observed in the EMG variables despite a decrease in muscle strength performance, in terms of peak torque, work and power to about 50% of initial values after 100 contractions. The concomitantly obtained positive correlation between the increase in EMG/torque ratio and the individual percentage of fast twitch (FT) muscle fibres indicated that local factors in the muscle, primarily in FT fibres, were causing the development of fatigue during repeated dynamic contractions with high power outputs.

Effect of halothane on arterial hepatic flow as reflected at coeliac angiography

During halothane anaesthesia the hepatic blood flow may be reduced. This effect interferes with the angiographic investigation of the liver and this is demonstrated by the case presented.

Urethrocystography during and after transurethral prostatic resection

Ten men were subjected to transurethral electroresection because of prostatic adenoma. All were examined with urethrocystography on 3 occasions, viz. at the end of operation, 4-7 days later and after a further 2-3 months. Peroperative examination for residual adenoma appeared to be of little value, while examination a few days after the operation revealed residual adenomas in 2 cases and possibly also in a third. The cavity left after the operation had the same size at the peroperative and the first postoperative examination, though its outline was sometimes smoother at the latter. During urination the cavity invariably increased in size. At the second postoperative examination the operation cavity was clearly smaller and its outline smoother in 9 of 10 cases. The cavity still expanded during micturition. No passage of contrast medium to the veins was ever demonstrable. At the peroperative examination the contrast medium was not injected under any substantial pressure and the cavity was not exposed to pressure by micturition. Even at the first postoperative examination, when the operation cavity was exposed to pressure by urination, the veins that had been opened at operation had closed so effectively that no contrast medium passed outside the prostatic capsule. Urethrocystography in association with TUR of prostatic adenoma is of interest to the urological surgeon. It provides him with a possibility to check his work very carefully.