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Biomedical subjects

M Hashiba

Publications and source records attributed to M Hashiba.

At least 19 recordsLinked to original sources
PubMed2001

Control and modulation of canal driven vestibulo-ocular reflex.

It has been well known that the canal driven vestibulo-ocular reflex (VOR) is controlled and modulated through the central nervous system by external sensory information (e.g. visual, otolithic and somatosensory inputs) and by mental conditions. Because the origin of retinal image motion exists both in the subjects (eye, head and body motions) and in the external world (object motion), the head motion should be canceled and/or the object should be followed by smooth eye movements. Human has developed a lot of central nervous mechanisms for smooth eye movements (e.g. VOR, optokinetic reflex and smooth pursuit eye movements). These mechanisms are thought to work for the purpose of better seeing. Distinct mechanism will work in appropriate self motion and/or object motion. As the results, whole mechanisms are controlled in a purpose-directed manner. This can be achieved by a self-organizing holistic system. Holistic system is very useful for understanding human oculomotor behavior.

Acceleration↗
PubMed2001

Passage of dextran magnetite nanoparticles through the subcupular space of the pigeon.

We examined the permeability of the subcupular space for endolymph flow in the pigeon. A new technique was developed in which nanoparticles consisting of dextran magnetite were attracted by use of a magnet, instead of injecting a dye solution. The method was revealed to prevent an excess pressure application by the injection of dye solution. The Berlin blue color resulting from the dextran magnetite nanoparticles was found mainly within the subcupular space contacting with the sensory hairs. Further formation of the Berlin blue was found within the sensory cells. The result supports the idea that the fluid passes through the subcupular space.

Animals↗
PubMed2001

Cupular response and functional anatomy to pressure application in the pigeon.

In this study, horizontal semicircular canal of the pigeon was inserted with a microfill, 164 micrometers in outer diameter, to gauge the pressure change in the canal and to clarify two things. One is whether the endolymph passes through the crista ampullaris or not. The other is as to the space where the endolymph passes through in the crista ampullaris if the endolymph goes through the crista. The pressure applications were performed by using Evans blue solution and as a result three pressure groups, i.e., 1) high, 2) moderate and 3) low were discriminated. Our results suggest that the endolymphatic fluid passes through the subcupular space or the top of the crista ampullaris when the pressure is enough small like the head rotates in daily life. Accordingly we present a new hypothesis as to the functional anatomy of the cupula in contrast to current hypotheses e.g. drum membrane or revolving door.

Animals↗
PubMed2000

Accessing endoscopic images for remote conference and diagnosis using WWW server with a secure socket layer.

Out of 137 hospitals in Niigata prefecture, 13 are connected to the Internet. The number of private clinics using the Internet has also increased. It is thought that an endoscopic information exchange over the Internet connection is useful for the cooperation between hospitals, clinics and organizations in related fields. A conventional World Wide Web (WWW) server of endoscopic images has been built around a compressed JPEG (Joint Panel Expert Group) format, for remote conferences and diagnoses. It has been made secure using a proxy server, a firewall server and a Secure Socket Layer (SSL). It is easy to access the server and view these endoscopic images using the usual homepage browsing method. Ordinarily, gastroenterologists would diagnose lesions with endoscopy in most cases. It is suggested that this conventional WWW server will be effective for remote conferences in some cases, even consultation will be possible.

Endoscopy, Gastrointestinal↗
PubMed1999

[Time constant of forward body sway induced by downward optokinetic stimulus].

Forward body sway induced by a downward optokinetic stimulus (OKS) was observed in 38 healthy subjects. The downward OKS was generated by a moving random dot pattern projected onto a half-pipe screen 2 m in diameter and was provided by a rectangular-like step function with velocities of 10, 20, 30 and 40 deg/sec. A fixation target was set by a red laser spot projected onto the screen in front of the subjects. As an additional stimulatory condition, 20 deg/sec of OKS with no fixation target was employed. The induced forward body sway was measured by a force-detecting platform as displacement of the center of gravity (COG). The gradual forward shift of COG followed by the plateau state was closely akin to a graphical representation of an equation of the first order lag time. As OKS velocities increased, the plateau level increased. Curve fitting analysis using a computer was employed to establish an approximation equation of the first order lag time. This analysis showed that the time constant of the optokinetic spinal response system was approximately 15 sec and the value of the time constant was independent of OKS velocity. Based on this long time constant, we concluded that the postural readjustment induced by OKS mainly plays a role in the low frequency range of human postural control.

Eye Movements↗
PubMed1998

Transient change in standing posture after linear treadmill locomotion.

Postural sway was measured in 24 healthy subjects after running or walking with eyes open on a standard treadmill exerciser. The speeds of running and walking were set at 10 and 7 km/h, respectively, and locomotion was maintained for 7 min. The postural sway response was characterized by systematic forward displacement followed by gradual decay to baseline and was accompanied by self-motion perception. Mean fore-back postural after sway was significantly greater after treadmill running than after normal running. The aftereffects of treadmill walking were significantly less than those of treadmill running. The 6 subjects showing distinct forward postural sway after treadmill walking were instructed to walk on the treadmill with their eyes closed. After this, none of the 6 subjects felt self-motion perception and had no evidence of postural aftersway. These results clearly demonstrate that vision during treadmill locomotion plays an important role in evoking postural sway after treadmill locomotion. It can be inferred that somatosensory/motor signals may be stored during visual-somatosensory/motor conflict and that this stored information may evoke postural change and self-motion perception.

Adult↗
PubMed1998

[Inhibitory effect of macrolide antibiotics on biofilm formation by Pseudomonas aeruginosa].

In recent years, various medical indwelling devices have been developed and used. Bacteria adhering to these devices often cause refractory infection. In the field of otolaryngology, refractory infection accompanying these medical indwelling devices such as middle ear ventilation tubes and artificial auditory ossicles has been reported. The concept of bacterial biofilm infection has been suggested as an explanation for the refractory infection. Furthermore it has been reported that a bacterial biofilm is involved in refractory infection unrelated to medical indwelling devices. Topical biofilm formation was detected in patients with chronic sinusitis, chronic purulent otitis media or habitual tonsillitis. In this study, we morphologically and quantitatively examined the biofilm-forming capacity of a clinically isolated strain of mucoid type Psecudomonas aeruginosa on Teflon to investigate the effects of macrolide antibiotics on bacterial biofilm formation. In the morphological examination, P.aeruginosa was cultured together with a Teflon sheet in minimal medium containing various concentrations of the macrolide antibiotics clarithromycin (CAM), erythromycin (EM) and midecamycin (MDM), at 37 degrees C for 7 days. The surfaces of the Teflon sheets were examined by electron microscopy. The adherent bacteria and biofilm formation on Teflon sheets soaked in minimal medium containing CAM or EM were found to be decreased in a dose-dependent manner. However, in the Teflon sheets soaked in minimal medium containing MDM, there was no decrease in biofilm formation regardless of the MDM concentration. In the quantitative examination, P. aeruginosa was cultured in minimal medium containing various concentrations of the macrolide antibiotics at 37 degrees C for 7 days together with Teflon beads. The levels of hexose, protein and alginate adhering to the Telfon beads were quantified as an estimation of biofilm formation. On Teflon beads treated with CAM or EM, there were dose-dependent decreases in hexose, protein and alginate levels. In particular, marked decreases were noted when CAM and EM concentrations were 10 micrograms/ml or more. Furthermore, there was no significant difference between CAM and EM. However, in the presence of MDM, there was no decrease in hexose, protein or alginate levels regardless of the MDM concentration. The minimal inhibitory concentration (MIC100) of each macrolide against P. aeruginosa used in this experiment was 100 micrograms/ml or more. There may be no bactericidal effect on this strain at the macrolide concentrations used in this experiment. However, this experiment used 7-day treatment. The long-term bactericidal activity of macrolides was examined. In the presence of CAM or MDM, bacterial levels after culture were similar to preculture levels or slightly lower than the preculture levels. In the presence of EM, bacterial levels were similar to the preculture levels. These results demonstrated that CAM and EM, which are 14-membered macrolides inhibited biofilm formation, while MDM which is 16-membered macrolide, did not. These inhibitory effects of CAM and EM may be related to actions other than bactericidal activity. In our experiment, CAM and EM inhibited biofilm formation at 10 micrograms/ml or more. This concentration corresponded to 1/20 x MIC. This concentration can be achieved in tissues, nasal discharge and sputum with actual clinical doses. Therefore, these agents may be effective against biofilm disease caused by P. aeruginosa in the field of otolaryngology.

Anti-Bacterial Agents↗
PubMed1997

Hepatic damage influences the decay of nitroxide radicals in mice--an in vivo ESR study.

To determine the role of the liver in the elimination of free radicals from the body, the clearance rate (K) of nitroxide radicals (Tempol) at the hepatic domain was compared with that at the pelvic domain of live mice, using L-band ESR spectroscopy. The reduction of Tempol in biopsy specimens (liver tissue and femoral muscle) and blood obtained from Tempol-treated mice was also monitored using X-band ESR spectroscopy. Results indicated that the reduction of nitroxide radicals was delayed in both the liver and peripheral tissues when the liver was damaged. The decrease in both blood supply and reductants in the damaged liver might be involved in delaying the reduction in the whole body, because the liver can reduce the radicals supplied via the blood from the peripheral tissues, and the reductants such as reduced, glutathione in the peripheral tissues are supplied from the liver.

Animals↗
PubMed1997

[Study of non-visually induced smooth pursuit eye movements and their predictability using pseudorandom target motion].

It has been found that the smooth pursuit eye movements (SPEM) are elicited by not only visual stimuli but also non-visual information such as the subject's fingertip movement and a moving sound source. We have already reported the quantitative analysis of SPEM which were induced by somatosensory and acoustic information. In the previous study, we used a sinusoidal waveform that could be highly predictable. Since it is wellknown that predictive control has an important role in the normal SPEM, we expect the predictive control to function in non-visually induced SPEM (NVSPEM). We quantitatively analyzed NVSPEM and normal SPEM evoked by pseudorandom target motion in ten human subjects who had no ocular, oculomotor or vestibular disorders. NVSPEM were induced by the following two non-visual targets: 1, subjects' fingertip motion as a somatosensory target ("Somato"), 2, a small loudspeaker (3-cm diameter.) generating white noise with an intensity of about 60 dB (A) as an acoustic target ("Acoustic"). A servo-controlled swing arm of 50cm was used to drive the subject's fingertip and the acoustic target of the small loudspeaker. The horizontal motion of the swing arm was controlled by a personal computer. The pseudorandom target motion was generated by mixing four sinusoids (0.1, 0.2, 0.4, 0.8 Hz) of which the phases were randomly selected and the peak velocities were equally set at 19 deg/s. The mean peak velocity of the target was 26.2 deg/s and the amplitude was limited within 15 deg. Horizontal eye movements were recorded by DC electro-oculography and on an analogue datatape. The experiment was performed for 30 s in complete darkness so that the subjects' fingertip and loudspeaker as such remain invisible to the subject. Signals from the data recorder were smoothed by a low pass analogue filter of 20Hz, after digitization with a sampling frequency of 200 Hz and precision of 12 bits, and stored on a computer. The slow and quick eye movement components, both of which were present in each class of horizontal eye movement investigated, were identified and separated by a computer. Then we developed a method of automatic quantitative analysis of ocular tracking eye movement. Gain and phase values for the smooth pursuit eye movements were obtained in each condition. In the lower frequency area, the gain elicited by the pseudorandom stimulation was lower than the smooth pursuit gain for sinusoidal (predictable) stimulation in all conditions. In the highest frequency, gain values did not differ significantly among the three. For the sinusoidal stimulation, the phase of the smooth component of "Visual" always had a lag and that of "Somato" and "Acoustic" had a lead in lower frequencies. All conditions had a phase shift, decreasing with increasing frequency. For the pseudorandom stimulation the phase of the SPEM had a lead only in the lowest frequency (0.1 Hz). On the other hand, in the NVSPEM the phases of the three lower frequencies had a lead which had a tendency of a larger phase lead with decreasingly frequency. In the highest frequency (0.8 Hz), we could see a short phase lag. These findings support the idea that SPEM and NVSPEM have a mutual or similar physiologic system and overlap part of the anatomical pathway.

Adult↗