The rate of action of calcium on the electrical and mechanical responses of the crayfish muscle fibers

The effects of sudden changes in external Ca concentration on the time courses of the changes in size of the action potential and of the associated contraction in a single crayfish muscle fiber were investigated. Procaine-HCl was added to the bathing solution to make the muscle fiber excitable. The concentration of the divalent cations (Ca and Mg) was high enough to keep the threshold potential constant. In Ca-free solution, neither action potential nor contraction was observed. When the external Ca concentration was suddenly increased from 0 to 14 mM, the full sized action potentials were generated within several seconds, but the tensions recovered slowly in an exponential time course with the time constants of 15-40 sec depending on the muscle fiber radius. The tension recovery was further delayed by addition of Dextran to the bathing solution, and it was also slowed at temperatures as low as 4-5 degrees C. When the Ca concentration was changed from 14 mM to 0 mM, the decreased in action potential was slow rather than instantaneous. The delay in tension recovery was attributed to the diffusion time of Ca ions into the TTS, and it was suggested that the Ca entry through the TTS membranes was the first step in the excitation-contraction coupling of the crayfish muscle fibers. The diffusion coefficient of Ca ions inside the TTS was calculated from the recovery time of tension development. It was one order smaller than that in free solution.

Effects of gastrointestinal and related hormones on glycogenolysis and gluconeogenesis in cultured liver cells

When isolated rat liver cells were incubated for 15 min in the presence of vasoactive intestinal peptide, secretin, gastrin, caerulein or glucagon at concentrations ranging from 0.2 microgram to 2 microgram per ml, glycogenolysis was stimulated. Among the gastrointestinal hormones or peptides tested, vasoactive intestinal peptide had the highest stimulatory activity. However, somatostatin was inhibitory for liver glycogenolysis. Combination experiments showed that somatostatin also inhibited the stimulatory effects of vasoactive intestinal peptide and secretin, but not that of glucagon, while glucagon and vasoactive intestinal peptide, or glucagon and secretin showed additive effects on glycogenolysis, but secretin and vasoactive intestinal peptide did not. The results suffest that the receptor site of glucagon is different from those of secretin and vasoactive intestinal peptide. Slight but significant stimulation of gluconeogenesis was also observed by vasoactive intestinal peptide and secretin. The evidence presented in this paper indicates that the so-called enterohepatic axis, in which a part of serum glucose levels is regulated directly by gastrointestinal hormones, exists and that the axis is inhibited by somatostatin.

[The treatment of carcinoma of the tongue (author's transl)]

In the past 18 years 34 patients (21 males and 13 females) with carcinoma of the tongue were treated in the author's clinic. Patients with T1N0 lesions were treated satisfactorily only with irradiation. Patients with advanced disease, such as T2-T4 with metastases, were classified into 2 groups. One group was treated surgically (hemiglosectomy and radical neck dissection) and postoperative irradiation (about 6000 rads). The other group was treated with preoperative irradiation (about 4000 rads) and the same operation as the first groups. The results are significantly different. In the first group, 15 patients out of 17 died from local or cervical recurrences, whilst in the latter group 12 patients of 14 are in good health. As two patients died from unknown disease the 5 year survival of this group is 100%.

Aortic cannulation for cardiopulmonary bypass

The surgical technique and complications of aortic cannulation for arterial return in total body perfusion utilizing oxygenator were presented based on our experience of 400 patients. Major complications encountered were laceration and bleeding (1 case), hematoma formation and bleeding (2 cases), and malpositioning of the catheter resulting in mild brain damage (1 case). All underwent re-operation with 4 survivals. Aortic cannulation is simple to perform, easy to maintian stability in cardiopulmonary bypass and with much less risk of retrograde dissection in all ages.

[Activation of contraction by voltage-clamped stimulation in crayfish muscle fibers (author's transl)]

It is known that the properties of the excitation-contraction coupling of crayfish skeletal muscle are different in some respects from those of frog muscle. In the present study, activation of contraction of the crayfish muscle induced by short depolarizing pulses was investigated and it was compared with the results of frog muscle obtained by Adrian, Chandler and Hodgkin (1969). Two glass microelectrodes were inserted into the thoracal muscle of the crayfish. The muscle was stimulated by the voltage-clamped pulses of different durations and the resulting contractions were observed under the binocular microscope with the magnification of 60 X at 20 approximately 23 degrees C. The rheobasic membrane potential was -55mV. The mechanical threshold potential was -42 mV for 10 msec, -15 mV for 2.5 msec, +18 mV for 1 msec and around +90 mV for 0.5 msec pulses. For short pulses where the threshold potential was more positive than -20 mV, the area of the depolarization above -30 mV was 51 mV-msec. Subthreshold pulses produced contraction if applied repetitively. The effect of a just suprathreshold short pulse on the activation of contraction was cancelled by the hyperpolarizing pulse.

Effects of radiation after enucleation without implantation on orbital development of patients with retinoblastoma

Orbital growth of the patients treated with enucleation and radiation in infancy for retinoblastoma was studied by roentgenographic measurements. The patients radiated following enucleation without implantation were found to be many in the present series, and the effects of radiation and the insertion of an implant to the development of the orbit in infancy were discussed. Judging from the results of statistical analysis of roentgenographic measurements of the orbit, growth retardation of the orbit radiated after enucleation was greater than that of the orbit only enucleated. Radiation therapy after enucleation for intraocular malignant tumor in infancy should be avoided as much as possible unless the extrascleral invasion is found at operation.

Repetitive caffeine contractions in single crayfish muscle fibers

Crayfish muscle fiber responded to 1-4 mM caffeine with repetitive contractions. At 4 mM caffeine, two to four peaks with intervals of 2-3 sec were observed in the tension curve. At 2 mM caffeine, the intervals were prolonged so that the second contraction started after the first contraction ceased. The tension in the second contraction was slower and smaller than the first one. At 1 mM caffeine, very small tensions developed repetitively at intervals of about 1 min and lasted for more than an hour. The time courses of these caffeine contractions were not modified by the current flow in the direction of hyperpolarizing a major part of the muscle membrane. It was observed under a microscope that the contraction in caffeine solution was induced asynchronously. Moreover, repetitive contractions occurred at several sites and propagated in the longitudinal direction of the muscle fiber. The propagation velocities of contraction waves were between 330 and 40 mum/sec depending on the time after perfusion with caffeine solution.

Contraction produced by intracellular injection of calcium, strontium, and barium in the single crayfish muscle fibers

Ca ions were ionophoretically injected through an intracellular microelectrode into the single muscle fiber of a crayfish, and the resulting contraction sphere was observed under a microscope and photographed with a movie camera. The minimum contraction produced by the threshold current involved usually three or four, sometimes two, sarcomers on both sides of the injecting pipette but contraction involving only one sarcomere was not observered. The rheobase of the Ca-injecting current was 3.2 X 10(-9) A. The strength-duration curves were determined for Ca-, Sr-, and Ba-injecting currents; all fitted a similar hyperbolic equation. The threshold amount of Ca above rheobasic injection was 2.1 X 10(-15)mol, and the ratios between threshold amounts were Ca: Sr: Ba=1: 1.9: 3.0. The effects of Ca and Sr were additive for the contraction. More current was required for the Ca-injection to produce the contraction in the K-depolarized-or 15mM-procaine-treated muscle, although less current was sufficient for the muscle treated with 0.5-1.0 mM of caffeine. The participation of the Ca-induced Ca release mechanism in the contraction produced by Ca injection and the role of Sr or Ba as a substitute for Ca were discussed.

Speckle noise reduction by random phase shifters

Experimental results are given that show that a random phase shifter (RPS) is effective in reducing speckle noise caused by optical defects in coherent imaging systems, including holographic imaging systems. Here the RPS is composed of many tiny transparent blocks, each of which gives a definite phase shift such as O or pi to the transmitting light; and the distribution of the phase shift is two-dimensionally random. The optical defects are scattering centers such as scratches or dust on lenses or on the hologram medium in the case of holographic imaging systems.

Toxic polyneuropathy due to glue sniffing

Four cases of toxic polyneuropathy due to glue-sniffing were reported. Neurological examination revealed motor predominant mixed type polyneuropathy. The cause of polyneuropathies in these cases was considered to be due to the inhalation of the vaporized elements of the adhesive agent, which contain mainly n-hexane and toluene. N-hexane is considered to be chiefly responsible for the polyneuropathy, though toluene also could have some influence on the illness.

Studies on Cavitation Erosion

Cavitation damage tests of iron and steel have been carried out using two types of experimental facilities. One is a water tunnel system which presumably simulates the field conditions fairly closely and the other is a magnetostriction vibratory unit commonly used for accelerated cavitation erosion testing of metals. A comparison between water tunnel and vibratory tests shows a difference in mechanism of cavitation damage. Consequently, it has been concluded that the application of the test results obtained in a magnetostriction vibratory apparatus should be limited to provide rough data for the primary selection of proper materials to be used in the construction of hydraulic units and other industrial systems, unless damage is caused under similar conditions to that of the vibratory apparatus.