Thermal helix-coil transition in UV irradiated collagen from rat tail tendon

The thermal helix-coil transition in UV irradiated collagen solution, collagen film and pieces of rat tail tendon (RTT) were compared. Their thermal stability's were determined by differential scanning calorimeter (DSC) and by viscometric measurements. The denaturation temperatures of collagen solution, film and pieces of RTT were different. The helix-coil transition occur near 40 degrees C in collagen solution, near 112 degrees C in collagen film, and near 101 degrees C in pieces of RTT. After UV irradiation the thermal helix-coil transition of collagen samples were changed. These changes depend on the degree of hydratation.

Age-related muscle stiffness: predominance of non-reflex factors

This study was aimed at assessing the contribution of reflex and non-reflex factors to the muscle tone of old female Wistar rats. The hind foot of a rat was flexed or extended at the ankle joint by 25 degrees over 250 ms. The resistance of the foot to passive movements (torque, mechanomyogram), as well as the reflex electromyographic activity in the gastrocnemius and tibialis anterior muscles, were recorded simultaneously. Moreover, the impact of the blockade of the reflex activity caused by the local anesthetic lignocaine (1-2 ml of a 2% solution, injected in the vicinity of the sciatic nerve) on the muscle tone was investigated. Additionally, old rats' hind leg muscle samples were analysed using fluorescent microscopy for the expression of fibronectin, which is an early marker of connective tissue formation. It has been shown that old rats are characterized by (i) a substantially increased resistance of flexor muscle stiffness (measured during extension) and unchanged resistance of extensors (measured during flexion), (ii) the loss of a major part of the reflex electromyographic activity and (iii) the increased content of fibronectin in muscles. Moreover, it has been shown that lignocaine, which completely blocked the electromyographic reflex activity in the gastrocnemius and tibialis anterior muscles in young animals, was unable to counteract the resistance of these muscles to passive movements in old rats. The present results suggest that the muscle stiffness seen in old rats is not due to a reflex response, but depends mainly on non-reflex factors--chiefly on a large overgrowth of non-elastic connective tissue replacing degenerated active muscle fibers.

Sympathetic skin response (SSR) in multiple sclerosis

The function of the autonomic system in multiple sclerosis (MS) is often afflicted. In order to reveal the presence of autonomic disturbances examination of sympathetic skin response (SSR), as a simple non-invasive method of the evaluation of conduction in autonomic nervous system, was performed in 25 patients with clinically defined MS. The diagnosis was confirmed by MRI and evoked potentials studies. Bimodal type of stimulation was used: the median nerve was stimulated, then the auditory stimulus (burst) was presented to the patient. Responses were recorded simultaneously from the palms and soles. SSR was abnormal in 19 patients (76%). Absence of the response from lower limbs and normal response from upper limbs were found in 6 patients (24%), increase in latency and decrease in amplitude from upper and lower limbs were found in 8 patients (32%) and increase in latency, decrease in amplitude of the response from upper limbs with absence of the response from lower limbs were found in 5 patients (20%). SSR appears to be a simple and effective method of assessing sympathetic disturbances in multiple sclerosis.

Type III collagen deficient EDS IV producing muscular hypotonia with abnormal muscle fibroblasts

Muscle biopsy and fibroblast culture of a floppy child with Ehlers-Danlos syndrome type IV were studied. Biochemical analysis of the tissue showed drastically reduced amount of collagen type III. Electron microscopic examination of muscle as well as of cultured fibroblasts showed grossly dilated and dominated the cytoplasm endoplasmic reticulum. Dilatation may result from storage of an abnormal collagen type III molecule. Our observations indicate that type III collagen deficiency may be present clinically as a congenital muscle hypotonia. Specific ultrastructural abnormalities of fibroblasts found in muscle biopsy can enable the proper diagnosis.

Apoptosis: a basic pathological reaction of injured neonatal muscle

A light and electron microscopic study of immature muscle cell degeneration induced by bupivacaine (BPVC) was performed. The pattern of muscle cell death is related to muscle maturity; in newborn rats, cell death has the morphology of apoptosis, whereas in the older animals muscle cell death resembles cell necrosis and the ultrastructural feature of these changes are essentially the same as those described in adult muscle. The ability to undergo apoptosis in response to a pathological stimulus is a common effector mechanism of immature muscle.

[The Miller-Fisher syndrome during ECHO-7 neuro-infection. A case history]

The authors describe a case of a 36-year old male patient with the Miller Fisher syndrome of ophthalmoplegia, ataxia and areflexia. An apparent etiopathogenetic factor in this case appears to be ECHO 7 virus. The pathological process was localized in the brainstem.

Role of endogenous prostaglandins in duodenal alkaline response to luminal hydrochloric acid or arachidonic acid in conscious dogs

Duodenal secretion of HCO-3 and luminal release of PGE2 were measured in conscious dogs. The results show that the HCO-3 secretion is closely correlated with the luminal release of PGE2 and that both the HCO-3 and the PGE2 outputs increase dose-dependently after topical application of hydrochloric acid or arachidonic acid. Indomethacin reduced basal HCO-3 and PGE2 release and prevented their increase in response to hydrochloric acid or arachidonic acid. We conclude that mucosal PGE2 plays an important role in the alkaline secretion from the duodenum.

The effect of 6-hydroxydopamine and some hypotensive drugs on lypressin induced hypertension in rats

Intracerebroventricular injection of 6-hydroxydopamine (6-OH-DA) prevented the development of the lypressin (LVP)-induced hypertension. Administration of 6-OH-DA to hypertensive rats significantly decreased, but did not normalize, blood pressure. A fourteen-day treatment with clonidine, guanethidine, reserpine, dihydralazine, propranolol and furosemide produced a transient decrease in blood pressure in LVP-hypertensive rats. Eight weeks after the withdrawal of hypotensive drugs blood pressure again reached the value corresponding to that in untreated LVP-hypertensive rats.

Synthesis and effect of asymmetric 1,4-bis(aminoacyl) piperazines on neuromuscular transmission

The condensation of asymmetrically substituted 1,4-bis(haloacyl) piperazines with secondary amines yielded asymmetric 1,4-bis (aminoacyl) piperazines 3-6, which were further transformed into the respective dimethiodides 3b-6b by treatment with methyl iodide. Those compounds were found to inhibit the neuromuscular transmission by blocking the motor end-plate receptors. Compounds containing piperidine moiety and branched acyl chain 4b displayed enhanced activity.

Effects of clonidine, guanethidine and furosemide on the development of vasopressin hypertension in rat

The influence of clonidine, guanethidine and furosemide on the development of arterial hypertension was studied in rats with hypertension induced by repeated administration of lysine vasopressin. It was found that these drugs administered during long time periods together with lysine vasopressin prevented the development of arterial hypertension. When any of these drugs was given in combination with vasopressin plasma renin activity failed to rise and the level and turnover of catecholamines in rat brain were unchanged.

Myofibrillar protein pattern in experimental myotonia in rats

Experimental myotonia was induced in rats by long-term administration of 20,25-diazacholesterol. Electrophysiological, morphological and biochemical investigations were carried out on m. soleus, m. extensor digitorum longus and m. gastrocnemius. The effect of 20,25-diazacholesterol administration on myofibrillar proteins was studied and a significant rise in the concentration of a protein presumed to be alpha-actinin was demonstrated in m. gastrocnemius. A change of the same character, not statistically significant, was observed in the m. extensor digitorum longus.