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We have been developing a method of plasma gene transfection that uses microdischarge plasma (MDP) and is highly efficient, minimally invasive, and safe. Using this technique, electrical factors (such as the electrical current and electric field created through processing discharge plasma) and the chemical factors of active species and other substances focusing on radicals are supplied to the cells and then collectively work to introduce nucleic acids in the cell. In this paper, we focus on the electrical factors to identify whether the electric field or electrical current is the major factor acting on the cells. More specifically, we built a spatial distribution model that uses an electrical network to represent the buffer solution and cells separately, as a substitute for the previously reported uniform medium model (based on the finite element method), calculated the voltage and electrical current acting on cells, and examined their intensity. Although equivalent circuit models of single cells are widely used, this study was a novel attempt to build a model wherein adherent cells distributed in two dimensions were represented as a group of equivalent cell circuits and analyzed as an electrical network that included a buffer solution and a 96-well plate. Using this model, we could demonstrate the feasibility of applying equivalent circuit network analysis to calculate electrical factors using fewer components than those required for the finite element method, with regard to electrical processing systems targeting organisms. The results obtained through this equivalent circuit network analysis revealed for the first time that the distribution of voltage and current applied to a cellular membrane matched the spatial distribution of experimentally determined gene transfection efficiency and that the electrical current is the major factor contributing to introduction.

We examined the effect of trimidox-induced apoptosis involvement of p53 in the NALM-6 cell line of acute lymphoblastic leukemia. Trimidox has been shown to increase the induction of p53. Phosphorylation of p53 protein at Ser-15 and Ser-20 residues was activated earlier than the obvious increase in p53 expression. Pifithrin-α, a p53 inhibitor, significantly prevented trimidox-induced apoptotic characteristics, as detected by nuclear morphological observation and DNA fragmentation. Trimidox-induced apoptosis was enhanced or attenuated by transfection with wild-type or dominant-negative p53 containing expression vectors, respectively. These results indicate that one of the induction mechanisms of apoptosis by trimidox is the mediated augmentation of p53. Keywords:: trimidox, apoptosis, p53

Intrathecal (i.t.) administration of D-cycloserine (100 and 300 fmol), a partial agonist of the glycine recognition site on the N-methyl-D-aspartate (NMDA) receptor ion-channel complex, produced a behavioral response mainly consisting of biting and/or licking of the hindpaw and the tail along with slight hindlimb scratching directed toward the flank in mice, which peaked at 5 – 10 min and almost disappeared at 15 min after the injection. The behavior induced by D-cycloserine (300 fmol) was dose-dependently inhibited by an intraperitoneal injection of morphine (0.5 – 2 mg/kg), suggesting that the behavioral response is related to nociception. The nociceptive behavior was also dose-dependently inhibited by i.t. co-administration of 7-chlorokynurenic acid (0.25 – 4 nmol), a competitive antagonist of the glycine recognition site on the NMDA receptor ion-channel complex; D-(−)-2-amino-5-phosphonovaleric acid (62.5 – 500 pmol), a competitive NMDA receptor antagonist; MK-801 (62.5 – 500 pmol), an NMDA ion-channel blocker; ifenprodil (0.5 – 8 nmol); arcaine (31 – 125 pmol); and agmatine (0.1 – 10 pmol), all being antagonists of the polyamine recognition site on the NMDA receptor ion-channel complex. However, [D-Phe7,D-His9]-substance P(6 – 11), a specific antagonist for substance P (NK1) receptors, and MEN-10,376, a tachykinin NK2-receptor antagonist, had no effect on D-cycloserine-induced nociceptive behavior. These results in the mouse spinal cord suggest that D-cycloserine-induced nociceptive behavior is mediated through the activation of the NMDA receptor ion-channel complex by acting on the glycine recognition site and that it does not involve the tachykinin receptor mechanism. Keywords:: D-cycloserine, N-methyl-D-aspartate (NMDA) receptor ion-channel complex, nociceptive behavior (mice), intrathecal administration

The gene/molecule introduction method using surface discharge enables transfection into a wider area, compared with the micro-plasma method. In this research, as the first step in elucidating the gene transfer mechanism in the surface discharge method, it was revealed that endocytosis is the main introduction mechanism in the surface discharge method, and that 80% of the introduction is due to endocytosis. Furthermore, the relationship between the size of the target molecule and the transfection efficiency was investigated. As a result, it was made clear that when target molecules with a molecular weight of up to 10 000 bp, the transfection efficiency is proportional to the collision frequency between the target molecule and cell. On the other hand, it became clear that when the molecular weight exceeds 10 000 bp, the transfection efficiency decreases with increasing molecular weight, and that almost no introduction is made at 15 000 bp or more. [ABSTRACT FROM AUTHOR]

In order to clarify the mechanism of plasma gene transfection, the relationship between transfection efficiency and transferred molecular size was investigated. Molecules with low molecular mass (less than 50 kDa; dye or dye-labeled oligonucleotide) and high molecular mass (more than 1 MDa; plasmid DNA or fragment of plasmid DNA) were transferred to L-929 cells. It was found that the transfection efficiency decreases with increasing in transferred molecular size and also depends on the tertiary structure of transferred molecules. Moreover, it was suggested the transfection mechanism is different between the molecules with low (less than 50 kDa) and high molecular mass (higher than 1 MDa). For the amount of gene transfection after plasma irradiation, which is comparable to that during plasma irradiation, it is shown that H2O2 molecules are the main contributor. The transfection efficiency decreased to 0.40 ± 0.22 upon scavenging the H2O2 generated by plasma irradiation using the catalase. On the other hand, when the H2O2 solution is dropped into the cell suspension without plasma irradiation, the transfection efficiency is almost 0%. In these results, it is also suggested that there is a synergetic effect of H2O2 with electrical factors or other reactive species generated by plasma irradiation. [ABSTRACT FROM AUTHOR]

Plasma gene transfection is expected as a safe and useful method of gene transfection. However, in this method, there is difficulty in keeping both high transfection efficiency and less cell damage simultaneously. The authors have evaluated transfection efficiency and cell viability using four different plasma sources, such as arc discharge, plasma jet, dielectric barrier discharge (DBD), and microplasma. A high transfection efficiency was achieved by discharge forms in which the electric current flows via the cells. This suggested that an electric current plays an important role in plasma gene transfection. The total volume of gas flow must be small or zero and the area in which the cells are directly irradiated by plasma must be small in order to achieve a higher cell viability. The microplasma that satisfies these conditions achieved both the highest transfection efficiency and the highest cell viability simultaneously. [ABSTRACT FROM AUTHOR]

Focuses on the role of endogenous pituitary adenylate cyclase-activating polypeptide (PCAP) in catecholamine secretion from the rat adrenal gland. Role of PCAP, to facilitate the neurally evoked catecholamine secretion; Effect of PCAP on catecholamine output responses.

This study has been done to know what kind of factors in plasmas and processes on cells induce plasma gene transfection. We evaluated the contribution weight of three groups of the effects and processes, i.e. electrical, chemical and biochemical ones, inducing gene transfection. First, the laser produced plasma (LPP) was employed to estimate the contribution of the chemical factors. Second, liposomes were fabricated and employed to evaluate the effects of plasma irradiation on membrane under the condition without biochemical reaction. Third, the clathrin-dependent endocytosis, one of the biochemical processes was suppressed. It becomes clear that chemical factors (radicals and reactive oxygen/nitrogen species) do not work by itself alone and electrical factors (electrical current, charge and field) are essential to plasma gene transfection. It turned out the clathrin-dependent endocytosis is the process of the transfection against the 60% in all the transfected cells. The endocytosis and electrical poration are dominant in plasma gene transfection, and neither permeation through ion channels nor chemical poration is dominant processes. The simultaneous achievement of high transfection efficiency and high cell survivability is attributed to the optimization of the contribution weight among three groups of processes by controlling the weight of electrical and chemical factors. [ABSTRACT FROM AUTHOR]