Biomechanical comparison of stimulated and nonstimulated skeletal muscle pulled to failure

We compared the biomechanical properties of passive and stimulated muscle rapidly lengthened to failure in an experimental animal model. The mechanical parameters compared were force to tear, change in length to tear, site of failure, and energy absorbed by the muscle-tendon unit before failure. Paired comparisons were made between 1) muscles stimulated at 64 Hz (tetanic stimulation) and passive (no stimulation) muscles, 2) muscles stimulated at 16 Hz (wave-summated stimulation) and passive muscles, and 3) muscles stimulated at 64 Hz and at 16 Hz. Both tetanically stimulated and wave-summation contracted muscles required a greater force to tear (at 64 Hz, 12.86 N more, P less than 0.0004; and at 16 Hz, 17.79 N more, P less than 0.003) than their nonstimulated controls, while there was no statistical difference in failure force between muscles stimulated at 16 Hz and 64 Hz. The energy absorbed was statistically greater for the stimulated muscles than for the passive muscles in Groups 1 and 2 (at 64 Hz, 100% more, P less than 0.0003; and 16 Hz, 88% more, P less than 0.0002). In Group 3, the tetanically contracted muscle-tendon units absorbed 18% more energy than the wave-summated stimulated muscles (P less than 0.01). All muscles tore at the distal musculotendinous junction, and there was no difference in the length increase at tear between muscles in each group. These findings may lead to enhanced understanding of the mechanism and physiology of muscle strain injuries.     

Leading etiologic factors in periventricular bleeding and periventricular leukomalacia

Prenatal, intrapartum and postnatal factors were investigated in less than 32 gestational age preterm infants known to have periventricular haemorrhage or periventricular leukomalacia. The diagnoses were established on cranial ultrasonography and/or autopsy. Factors associated with periventricular haemorrhage were: postnatal severe hypercapnia, acidosis and hypoxia. In the periventricular leukomalacia group the incidence of antepartum and intrapartum hypoxia and/or ischaemia (antepartum haemorrhage) were significantly higher than in the control group.     

The hepatotropic properties of nonsteroidal anti-inflammatory agents

The hepatotropic effect of nonsteroidal anti-inflammatory drugs (NSAID) such as indomethacin, voltaren, piroxicam, phenylbutazon, mefenamic acid was studied. It was found that according to their level of the pharmacological protection of the liver against tetrachlormethan these agents may be arranged in the following sequence: mefenamic acid, phenylbutazon, voltaren, piroxicam. The hepatoprotective effect of NSAID correlates with the antioxidant properties and fails to correlate with the antioxidant ones. The hepatotoxic effect of NSAID was determined by their ability to suppress synthesis of prostaglandins.     

Protection of CGS 10078B against ouabain-induced arrhythmia in the cat

CGS 10078B (CGS; 1-[2,3-dihydro-1,4-(2S)-benzodioxin-2-yl]-5-[2,3-dihydro-1,4-(2R)- benzodioxin-2-yl]-3-(1R,5S)-aza-1,5-pentanediol methane sulfonate) is an agent with alpha- and beta-receptor and calcium channel blocking actions. To study its antiarrhythmic activity, cats were anesthetized with alpha-chloralose, ventilated, and given atropine and gallamine. CGS (10 or 20 mg/kg, i.v.) was infused 15 min prior to ouabain. Bolus injections of ouabain (25 micrograms/kg, i.v.) were given every 15 min until death (D). Some cats were pretreated with reserpine (R; 5 mg/kg, i.p.) 24 h prior to the experiment. In other cats 6-hydroxydopamine (6-OHDA; 20 mg/kg, i.v.) was administered 3 days prior to CGS 20 mg/kg and ouabain. Data were compared with those of Lathers [Eur. J. Pharmacol. 64: 95, 1980], i.e., with 12 cats who received only ouabain and with 11 pretreated with timolol (T; 5 mg/kg, i.v.) prior to ouabain. After CGS (10 or 20 mg/kg, i.v.), but just prior to the first dose of ouabain, the blood pressure (BP) was decreased (p less than 0.05) from control (165 +/- 6 vs. 96 +/- 7, and 136 +/- 5 vs. 90 +/- 10 mm Hg, respectively). Comparable heart rate (HR) values were also decreased (p less than 0.05) from 225 +/- 17 to 166 +/- 14 and from 193 +/- 8 to 152 +/- 6 beats/min. 11 min after T, BP and HR had decreased (p less than 0.05) from 133 +/- 6 to 103 +/- 7 mm Hg and from 134 +/- 4 to 104 +/- 6 beats/min, respectively. Ouabain did not influence these decreases in BP and HR. CGS (10 or 20 mg/kg, i.v.) increased (p less than 0.05) the time to ouabain-induced arrhythmia (AR) and D. The magnitude of the protection appeared to be similar to that afforded by T. R given prior to CGS (20 mg/kg, i.v.) also increased the time to ouabain-induced AR and D while 6-OHDA increased the time to AR. The CGS protection against ouabain-induced AR was still present in animals pretreated with R or 6-OHDA. This indicates that the antiarrhythmic affect is not dependent upon adrenergic neuronal blockade.     

Effect of euphylline and no-shpa on cerebrovascular resistance and the survivability of animals after cerebral ischemia

In acute experiments on anesthetized cats with total ischemia of the brain (15-minute arrest of blood autoperfusion of the cerebral vessels by a stable blood volume) it was shown that euphylline and no-shpa administered before ischemia or in the early period after ischemia inhibit or prevent the development of the postischemic phenomenon of non-recovery of the cerebral blood flow. The two drugs contributed to survival of albino rats following the brain ischemia produced by ligation of both carotid arteries.     

Participation of angiotensin II in learning and memory. III. Interactions of angiotensin II with GABAergic drugs

The experiments were carried out on male albino rats trained and tested for retention (24 hr later) in a shuttle-box. Angiotensin II (AT II) 0.10 micrograms intracerebroventricularly (i.c.v.), gamma-aminobutyric acid (GABA) 100 micrograms i.c.v., bicuculline 0.5 and 1.0 mg/kg intraperitoneally (i.p.), and picrotoxin 0.5 and 1.0 mg/kg i.p. administered independently or in combinations immediately after training. AT II was found to improve retention. GABA also facilitated retention. Combination of AT II + GABA potentiated the memory-improving effect of AT II. Bicuculline and picrotoxin at a dose of 0.5 mg/kg did not affect retention, while at a dose of 1.0 mg/kg they improved it. Combinations of AT II + bicuculline (0.5 mg/kg) and AT II + picrotoxin (0.5 mg/kg) abolished the retention-improving effect of AT II. Bicuculline (0.5 mg/kg) or picrotoxin (0.5 mg/kg) abolished the retention-facilitating effect of the combination of AT II + GABA as well as the potentiating action of GABA on the memory effect of AT II. These results suggest the participation of GABAergic transmission in the CNS in the mechanisms of the long-term memory-improving effect of AT II.     

Laminar organization of the main olfactory bulb of Podarcis hispanica: an electron microscopic and Golgi study

In this study, the lamination pattern of the main olfactory bulb (MOB) of P. hispanica has been described using EM and Golgi-impregnation techniques. Six layers could be distinguished from the external surface to the ventricles: olfactory nerve layer (ONL), glomerular layer (GL), external plexiform layer (EPL), mitral layer (ML), internal plexiform layer (IPL), and granular cell layer (GCL). In ONL unmyelinated axonic bundles from the olfactory mucosa are seen. The GL is defined by the presence of terminal ramifications of the mitral primary dendrites and by axonic terminals of the olfactory nerve. The EPL is a dendritic articulation layer between the mitral and granule cells, where a great density of dendrodendritic synaptic contacts has been found. The ML is defined by the large mitral cell somata, and the IPL by myelinated axonic bundles that run rostro-caudally. Finally, the GCL is characterized by the presence of granule cells. Using the Golgi-impregnation method, five different neuronal types have been described. In the glomerular layer, a small cell population is located; these neurons seem the periglomerular cells described in mammals. The second type corresponds to the mitral cell population and the morphological features of these cells resemble to those of mammals. The three remaining types constitute the granule cell population; this population is characterized by a great morphological heterogeneousness. However, these types have been differentiated according to their dendritic tree morphology and location of the cell body. A morphological gradient depending on the distance of cell body for each type to the ependymal layer, has been observed. In EM, four different types of neuronal cell bodies according to their location and ultrastructure have been defined. The laminar organization of the MOB of Podarcis is similar to that in all vertebrates. The results for the fine structure and dendritic tree morphology have revealed a high similarity between these reptiles and mammals.     

Spiral coils for arterial occlusion

Roentgen endovascular occlusion with spiral emboli was used in 240 patients with different diseases. The introduction of spiral emboli into the arteries of abdominal and retroperitoneal organs was fulfilled through usual angiographic catheters. Duration of the arterial occlusion was checked up in the following angiographic examinations and showed the devices described to be appropriate for a continuous arterial blockade. No complications resulting from the introduction of the spiral embolus were noted.