Biomedical subjects

Norio Matsumoto

Publications and source records attributed to Norio Matsumoto.

9 recordsLinked to original sources

PubMed2006

Effect of electrical stimulation of the internal capsule on nociceptive neurons responding to orofacial stimuli in the medullary dorsal horn of the rat.

Internal capsule (IC) stimulation has been used clinically to alleviate central pain. However, the neuronal mechanisms underlying pain relief by IC stimulation are poorly understood. In order to elucidate the analgesic mechanism, the effect of IC conditioning stimulation on nociceptive neurons in the rat medullary dorsal horn was investigated in the present study. Rats were anaesthetized with N(2)O-O(2) (2:1) and 0.5% halothane and were immobilized with pancuronium bromide. Two kinds of nociceptive neurons, wide dynamic range (WDR) and nociceptive specific (NS) neurons, responding to noxious stimulations of the face and oral structures were recorded in the trigeminal caudal nucleus and the medial reticular subnuclei. A test stimulus with a single rectangular pulse (2ms in duration, 5-70V) was applied to the centre of the receptive field. Responses in 55.9% of the WDR neurons and in 60% of the NS neurons were inhibited by conditioning stimuli to the ipsilateral IC with trains of 33 pulses (100-300microA) at 330Hz. The percents of peak inhibitory effects on WDR neurons and NS neurons were 78.1+/-25.0% (n=19) and 89.0+/-13.6% (n=3), respectively. The inhibitory effect continued for conditioning-test intervals of up to 500ms. Effective sites for conditioning stimulation were concentrated in the lateral side of the IC. These findings suggest that modulation of nociceptive transmission by IC stimulation occurs at second-order neurons via a presynaptic phenomenon by corticofugal fibers in the IC.

Animals↗

PubMed2003

Respiratory isozyme, two types of rusticyanin of Acidithiobacillus ferrooxidans.

Among the members of the copper protein superfamily, the type I enzyme rusticyanin, which is found as an electron carrier in the oxidative respiratory chain of Acidithiobacillus ferrooxidans, is the only one to have both a high redox potential and acid stability. Here we report that two forms of the rusticyanin gene (rus) are present in the genomes of some strains of A. ferrooxidans. The more common form of rus (type-A) was found to be present in all six strains studied, including those harboring only a single copy of the gene. In addition a less common form (type-B) occurred in strains harboring multiple copies of the gene. The two genes were expressed as rusticyanin isozymes with differing surface charges due to differences in their amino acid composition. Still, the copper coordination sites were completely conserved, thereby maintaining the high redox potential necessary for an electron carrier.

Acidithiobacillus↗

PubMed2002

Numerical simulation for electrochemical cultivation of iron oxidizing bacteria.

A numerical simulation model was constructed for electrochemical cultivation of iron oxidizing bacterium, Thiobacillus ferrooxidans, based on Monod's dual limitation equation. In this model, two limiting factors were examined, low supply of Fe(II) ion and dissolved oxygen, from empirical viewpoints. The simulation model was constructed taking into consideration the energy balance based on the amount of the electronic flow from the electrode to bacteria via an iron ion, and then to oxygen. The model consisted of a logarithmic bacterial growth phase during the first three days, followed by a plateau and growth limitation thereafter. The predicted results were in agreement with the actual growth under electrochemical cultivation. It was predicted the growth limiting factor would be changed from insufficient supply of Fe(II) ions to that of oxygen by decreasing the value of oxygen transfer constant K, which correlated with the aeration rate. The optimum aeration rate was determined for the ideal electrochemical cultivation. The algorithm described here can be used in any electrochemical cultivation by modifying the parameters for each system.

Bioreactors↗

PubMed2002

Fundamental studies of glucose oxidase deposition on a Pt electrode.

The direct electrodeposition of glucose oxidase (EC 1.1.3.4) on a platinum electrode was investigated as a means for controlled immobilization. The presence of a nonionic detergent, Triton X-100, was found essential to produce a multilayered deposit. Moreover, to work properly, the detergent must be present above its critical micelle concentration. Under these conditions, a deposit of approximately 50 enzyme layers (480 nm), with surface uniformity of +/-20 nm, was verified using an electrochemical quartz crystal microbalance and by atomic force microscopy. In the absence of detergent, a layer of 25 nm is formed. Contrary to most previous claims, the deposition, which is potential dependent but optimal at 1.3 V versus AgCl/Ag electrode, is not electrophoretically driven, but is instead controlled by a lowering of the pH at the electrode surface due to concomitant oxygen evolution.

Biosensing Techniques↗

PubMed2002

Electrochemically mediated electrodeposition/electropolymerization to yield a glucose microbiosensor with improved characteristics.

A procedure is described that provides for electrochemically mediated deposition of enzyme and a polymer layer permselective for endogenous electroactive species. Electrodeposition was first employed for the direct immobilization of glucose oxidase to produce a uniform, thin, and compact film on a Pt electrode. Electropolymerization of phenol was then employed to form an anti-interference and protective polyphenol film within the enzyme layer. In addition, a stability-reinforcing membrane derived from (3-aminopropyl)trimethoxysilane was constructed by electrochemically assisted cross-linking. This hybrid film outside the enzyme layer contributed to the improved stability and permselectivity. The resulting glucose sensor was characterized by a short response time (<4 s), high sensitivity (1200 nA/mM x cm2), low interference from endogenous electroactive species, and working lifetime of more than 50 days.

Biosensing Techniques↗

PubMed2002

Responses of diencephalic nociceptive neurones to orofacial stimuli and effects of internal capsule stimulation in the rat.

The effect of conditioning stimulation of the internal capsule on nociceptive neurones in the rat diencephalon was investigated. The animals were anaesthetised with N(2)O/O(2) (2:1) and 0.5% halothane, and immobilised with pancuronium bromide. Nociceptive neurones responding to noxious stimulation of the face and oral structures were recorded in the ventral posteromedial nucleus, posterior group and zona incerta. These neurones were classified into wide dynamic range and nociceptive-specific types. Functional segregation of these nociceptive neurones was not apparent within the nucleus or between nuclei. A test stimulus with a single rectangular pulse (5-70 V) was applied to the centre of the receptive field; the nociceptive neurones exhibited short- and/or long-latency responses. Both responses in about 45% of the nociceptive neurones were inhibited by conditioning stimuli to the contralateral internal capsule with trains of 33 pulses (300 microA) at 330 Hz. The percent inhibitory effects on the nociceptive neurones of each area were 68.0+/-14.8% (n = 6) in the ventral posteromedial nucleus, 72.8+/-12.4% (n = 4) in the posterior group and 61.5+/-7.5% (n = 4) in the zona incerta. Effective sites for conditioning stimulation were concentrated in the lateral side of the internal capsule, through which the corticofugal fibres from the somatosensory cortex pass. These findings suggest that the transmission of nociceptive information to the diencephalon is modulated by stimulation of the internal capsule at the level of the trigeminal sensory complex in the brainstem. They might provide a novel way to elucidate the neurophysiological basis for antinociception by stimulation of the internal capsule observed in clinical studies.

Animals↗

PubMed2002

Electrochemical regeneration of Fe(III) to support growth on anaerobic iron respiration.

Here we describe artificial help for the respiratory electron flow supporting anaerobic growth of Thiobacillus ferrooxidans through exogenous electrolysis. Flux between H(2) and a anode through cells was accomplished with electrochemical regeneration of iron. The electrochemical help resulted in a 12-fold increase in yield compared with the yield observed in its absence.

Anaerobiosis↗

PubMed2002

Anaerobic respiration using Fe(3+), S(0), and H(2) in the chemolithoautotrophic bacterium Acidithiobacillus ferrooxidans.

The chemolithoautotrophic bacterium Acidithiobacillus ferrooxidans has been known as an aerobe that respires on iron and sulfur. Here we show that the bacterium could chemolithoautotrophically grow not only on H(2)/O(2) under aerobic conditions but also on H(2)/Fe(3+), H(2)/S(0), or S(0)/Fe(3+) under anaerobic conditions. Anaerobic respiration using Fe(3+) or S(0) as an electron acceptor and H(2) or S(0) as an electron donor serves as a primary energy source of the bacterium. Anaerobic respiration based on reduction of Fe(3+) induced the bacterium to synthesize significant amounts of a c-type cytochrome that was purified as an acid-stable and soluble 28-kDa monomer. The purified cytochrome in the oxidized form was reduced in the presence of the crude extract, and the reduced cytochrome was reoxidized by Fe(3+). Respiration based on reduction of Fe(3+) coupled to oxidation of a c-type cytochrome may be involved in the primary mechanism of energy production in the bacterium on anaerobic iron respiration.

Anaerobiosis↗

PubMed1987

Physiological properties of tooth pulp-driven neurons in the first somatosensory cortex (SI) of the cat.

Tooth pulp-driven (TPD) neurons are found in the oral area of the first somatosensory cortex (SI) of the cat. They have been classified according to their discharge patterns in response to electrical stimulation of the tooth pulp: the fast (F) type, slow (S) type, and a fast (Fa) type accompanied by afterdischarges. The characteristics of each type of TPD neuron were investigated in cats anesthetized with nitrous oxide and halothane. In surface distribution, there was no biased localization for any of the types. However, F-type neurons receiving input from the mandibular tooth tended to be found more medially than F-types receiving maxillary input. These TPD neurons did not change their firing pattern even when the stimulus was intensified. Mean threshold of the F-type to tooth pulp stimulation was 7.8 +/- 1.6 V and tended to be lower than that of the S-type (16.3 +/- 3.0 V). Graded increases in tooth pulp stimulation produced progressive increases in discharge frequency of both types of neurons. An analysis of the power function in relation to stimulus vs. response demonstrated that the exponent of the S-type neuron was about 2.0, being significantly larger compared to the 0.8 value for the F-type. The mean number of pulps afferent to an F-type was 1.6, compared to 4.8 for an S-type or 4.3 for an Fa-type. The results suggest that F-type TPD neurons may play a more important part in localizing pulpal pain and in recognizing the intensity than the other types.

Action Potentials↗