Effects of negative air ions on activity of neural substrates involved in autonomic regulation in rats

The neural mechanism by which negative air ions (NAI) mediate the regulation of autonomic nervous system activity is still unknown. We examined the effects of NAI on physiological responses, such as blood pressure (BP), heart rate (HR), and heart rate variability (HRV) as well as neuronal activity, in the paraventricular nucleus of the hypothalamus (PVN), locus coeruleus (LC), nucleus ambiguus (NA), and nucleus of the solitary tract (NTS) with c-Fos immunohistochemistry in anesthetized, spontaneously breathing rats. In addition, we performed cervical vagotomy to reveal the afferent pathway involved in mediating the effects of NAI on autonomic regulation. NAI significantly decreased BP and HR, and increased HF power of the HRV spectrum. Significant decreases in c-Fos positive nuclei in the PVN and LC, and enhancement of c-Fos expression in the NA and NTS were induced by NAI. After vagotomy, these physiological and neuronal responses to NAI were not observed. These findings suggest that NAI can modulate autonomic regulation through inhibition of neuronal activity in PVN and LC as well as activation of NA neurons, and that these effects of NAI might be mediated via the vagus nerves.     

Eradication of melanoma in vitro and in vivo via targeting with a Killer-Red-containing telomerase-dependent adenovirus

Melanoma is a highly recalcitrant cancer and transformative therapy is necessary for the cure of this disease. We recently developed a telomerase-dependent adenovirus containing the fluorescent protein Killer-Red. In the present report, we first determined the efficacy of Killer-Red adenovirus combined with laser irradiation on human melanoma cell lines in vitro. Cell viability of human melanoma cells was reduced in a dose-dependent and irradiation-time-dependent manner. We used an intradermal xenografted melanoma model in nude mice to determine efficacy of the Killer-Red adenovirus. Intratumoral injection of Killer-Red adenovirus, combined with laser irradiation, eradicated the melanoma indicating the potential of a new paradigm of cancer therapy.     

Development of respiratory rhythms in perinatal chick embryos

In chick embryos, gas exchange takes place via the chorioallantoic membrane (CAM) and the lungs at approximately 1 day prior to hatching. The present study was designed to elucidate the development of respiratory rhythms in the chick embryo during the whole pipping (perinatal) period with a condenser-microphone measuring system. The microphone was hermetically attached on the eggshell over the air cell on day 18 of incubation. It first detected a cardiogenic signal (i.e. acoustocardiogram), and then beak clapping and breathing signals (acoustorespirogram, ARG). The first signals of lung ventilation appeared intermittently and irregularly approximately once per 5 s among the clapping signals after the embryo penetrated its beak into the air cell (internal pipping, IP). The respiratory rhythm then developed irregularly, with a subsequent more regular rate. The envelope pattern of breathing from the onset of IP through external pipping (EP) to hatching was constructed by a specially devised procedure, which eliminated external and internal noises. The envelope patterns indicated that the IP, EP and whole perinatal periods of 10 embryos were 14.1+/-6.4 (S.D.), 13.6+/-4.0 and 27.6+/-5.4 h, respectively. In addition, they also indicated the period of embryonic hatching activity (i.e. climax) which was 48+/-19 min. The development of respiratory rhythm was also shown by the instantaneous respiratory rate (IRR) which was designated as an inverse value of two adjacent ARG waves.     

Electrogenic Pump Current and ATP-Dependent H+ Efflux Across the Plasma Membrane of Nitellopsis obtusa

The correlation between the pump current and the ATP-dependentH⁺ efflux was examined in internodal cells of Nitellopsis obtusa.To control the cytoplasmic pH and ATP concentration, the tonoplastwas removed by intracellular perfusion with an EGTA-containingmedium. Two groups of perfused cells were prepared, one with1 mM ATP (+ATP cells) and the other without ATP but with hexokinaseand glucose (–ATP cells). The ATP-dependent H⁺ effluxwas calculated as the difference in H⁺ efflux between the +ATPand –ATP cells. Based on an electrically equivalent circuitmodel of the plasma membrane, the pump current was calculatedfrom the membrane potentials and the membrane resistances ofboth +ATP and –ATP cells. When the membrane potentialwas not too high (–220 mV), the ATP-dependent H⁺ current(19 mA m^–2) was almost equal to the pump current (20 mAm^–2) calculated from the electrical data. This indicatesthat the electrogenic pump current across the plasma membraneof Nitellopsis obtuse was mostly carried by H⁺. But when themembrane potential was high (–280 mV), the H⁺ currentwas lower than the pump current. The possible cause of thisdiscrepancy is discussed. (Received November 5, 1984; Accepted February 28, 1985)     

Possible involvement of protein phosphorylation/dephosphorylation in the modulation of Ca2+ channel in tonoplast-free cells ofNitellopsis

Summary The regulation of voltage-dependent Ca²⁺ channels by protein phosphorylation and dephosphorylation was studied using tonoplast-free cells ofNitellopsis. Since the Ca²⁺-channel activation has a dominant role in the membrane excitation of tonoplast-free cells (T. Shiina and M. Tazawa,J. Membrane Biol. 96:263–276, 1987), it seems to be reasonable to assume that any change of the membrane excitability reflects a modulation of the Ca²⁺ channel. When agents that enhance phosphoprotein dephosphorylation (protein kinase, inhibitor, phosphoprotein phosphatase-1, -2A) were introduced to the intracellular surface of the plasmalemma (twice-perfused tonoplast-free cells), the membrane potential depolarized and the membrane resistance decreased under current-clamp experiments. By contrast, when cells were challenged with agents that enhance protein phosphorylation (phosphoprotein phosphatase inhibitor-1, -naphthylphosphate), the membrane potential hyperpolarized, and the membrane resistance increased. When phosphoprotein phosphatase-1 or -2A was perfused, the current-voltage (I–V) curve which was obtained under ramp voltage-clamp condition exhibited the so-called N-shaped characteristic, indicating an acceleration of the Ca²⁺-channel activation. This effect was suppressed by the addition of phosphoprotein phosphatase inhibitors. ATP--S, which is assumed to stimulate protein phosphorylation, decreased the inward current in theI–V curve. The dependence of the Ca²⁺-channel activation on intracellular ATP was different between the once-perfused and twice-perfused cells. In once-perfused cells, the membrane excitability was reduced by low intracellular ATP concentration. By contrast, in twice-perfused cells, excitability was enhanced by ATP.     

Uptake and Utilization of Sugars in Cultured Rice Cells

Suspension cultured cells of rice (Oryza sativa) were grownin a medium containing sucrose. Sucrose was rapidly hydrolyzedextracellularly in the early stage of subculture with a concomitantdecrease in the medium pH. The hydrolysis may be due to cellwall associated acid invertase and may be promoted by acidificationof the medium. The resulting glucose and fructose seemed tobe utilized equally. The cells grown on either sucrose, glucoseor fructose contained each of these sugars and possessed cellwall associated invertase activity. Protoplasts prepared bycell wall degrading enzymes utilized preferentially glucoseor fructose rather than sucrose. These results suggest thatexogenous sucrose is hydrolyzed by the cell wall associatedinvertase to hexoses, which are then taken up and metabolized. (Received November 25, 1987; Accepted February 8, 1988)     

New Brachiopod Species <Emphasis Type="Italic">Leurosina katasumiensis</Emphasis> (Chonetida) from the Kungurian Katasumi Limestone of the Kusu Area,Central Japan

A new brachiopod species, Leurosina katasumiensis sp. nov. (order Chonetida, family Rugosochonetidae, subfamily Rugosochonetinae), is described from the Kungurian Stage (Lower Permian, Nabeyama Formation) of central Japan.     

Identification of potent lysophosphatidic acid receptor 5 (LPA5) antagonists as potential analgesic agents

Lysophosphatidic acid (LPA) plays an important role in a variety of cellular functions. In particular, LPA5 receptor is highly expressed in spinal cord and dorsal root ganglion, which are associated with pain. This fact prompted us to hypothesize that LPA5 antagonists show analgesic effects. To search for potent LPA5 antagonists with blood brain barrier (BBB) permeability, we conducted high throughput screening (HTS). In HTS campaign, we found a 2H-isoquinoline-1-one scaffold showing antagonistic activity against LPA5 and synthesized a series of 2H-isoquinoline-1-one derivatives and evaluated their LPA5 activities. Among these compounds, compound 7e showed potent LPA5 activity with an IC₅₀ value of 0.12?μM, and acceptable BBB permeability. Furthermore, it showed effective analgesic effect in a chronic constriction injury rat model. Therefore, 7e may have a potential as novel pain therapeutic approach.     

Does the low respiratory rate in unfertilized eggs result mainly from depression of the redox reaction catalyzed by flavoproteins? Analysis of the respiratory system by light-induced release of CO-mediated inhibition

In unfertilized eggs of the sea urchin, the quite low respiratory rate is enhanced by tetramethyl- p -phenylenediamine (TMPD), phenazine methosulfate (PMS) and sperm and this augmentation is completely inhibited by carbon monoxide (CO). Exposure to light releases eggs from this CO-mediated inhibition. The action spectra for photoreactivation of CO-inhibited cytochrome c oxidase in isolated mitochondria and CO-blocked respiration in TMPD-treated eggs were found to be similar to the absorption spectrum of CO-bound cytochrome aa ₃. In PMS-treated eggs and fertilized eggs, the maximum photoreactivation of CO-inhibited respiration occurred at a light fluence rate higher than that for maximum photoreactivation of CO-inhibited respiration in TMPD-treated eggs, with peaks at the same wavelengths as those in the absorption spectrum of reduced cytochrome b. A similar phenomenon was seen for NADH cytochrome c reductase in mitochondria. Thus, cytochrome c oxidase and NADH cytochrome c reductase, whose activities are not altered by fertilization, seem to be functional, even in unfertilized eggs. In unfertilized eggs, difference spectra indicated that PMS and sperm augmented cytochrome b reduction and that TMPD accelerated cytochrome c reduction without cytochrome b reduction. Therefore, it is likely that depression of electron transport to cytochrome b , which is augmented by PMS and sperm, is responsible for the low respiratory rate in unfertilized eggs.