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A Kawana

Publications and source records attributed to A Kawana.

9 recordsLinked to original sources
PubMed1995

The mechanisms of generation and propagation of synchronized bursting in developing networks of cortical neurons.

The characteristics and mechanisms of synchronized firing in developing networks of cultured cortical neurons were studied using multisite recording through planar electrode arrays (PEAs). With maturation of the network (from 3 to 40 d after plating), the frequency and propagation velocity of bursts increased markedly (approximately from 0.01 to 0.5 Hz and from 5 to 100 mm/sec, respectively), and the sensitivity to extracellular magnesium concentration (0-10 mM) decreased. The source of spontaneous bursts, estimated from the relative delay of onset of activity between electrodes, varied randomly with each burst. Physical separation of synchronously bursting networks into several parts using an ultraviolet laser, divided synchronous bursting into different frequencies and phases in each part. Focal stimulation through the PEA was effective at multiple sites in eliciting bursts, which propagated over the network from the site of stimulation. Stimulated bursts exhibited both an absolute refractory period and a relative refractory period, in which partially propagating bursts could be elicited. Periodic electrical stimulation (at 1 to 30 sec intervals) produced slower propagation velocities and smaller numbers of spikes per burst at shorter stimulation intervals. These results suggest that the generation and propagation of spontaneous synchronous bursts in cultured cortical neurons is governed by the level of spontaneous presynaptic firing, by the degree of connectivity of the network, and by a distributed balance between excitation and recovery processes.

Animals↗
PubMed1992

[Neuromyopathy induced by halothane anesthesia and muscle relaxants for status asthmaticus--report of 2 patients].

Two patients with status asthmaticus (a 30-year-old female and a 48-year-old male) who developed flaccid quadriplegia and sensory impairment of glove and stocking type after treatment with halothane, muscle relaxants (pancuronium and vecuronium) and steroid are described. They noted motor and sensory impairment immediately after recovery from control ventilation for treatment of status asthmaticus. Histochemical examinations of biopsied muscle demonstrated the necrosis and regeneration of muscle fibers and small diameters in type I fibers. These results suggested that the involvement of muscle (myopathy) was a consequence of the harmful action of halothane and muscle relaxants together with steroids on muscle fibers with subclinical fragility. The sensory impairment (neuropathy) was considered to have been produced mainly by the halothane together with muscle relaxants and aminoglycosides.

Adult↗
PubMed1992

Tardive dystonia and ceruletide effects: case report.

1. One schizophrenic patient with drug-induced tardive dystonia was treated with ceruletide. 2. After the injection, dystonia showed a tendency toward rapid amelioration in 3 days; meanwhile, however, mental manifestations became exacerbated within 3 weeks. 3. We discuss some aspects of the effects of ceruletide.

Adult↗
PubMed1991

Nerve growth factor-induced intracellular calcium ion release in chick dorsal root ganglion neurons.

Nerve growth factor (NGF) rapidly infused into the extracellular medium near cell bodies of cultured chick dorsal root ganglion neurons caused transient increases in intracellular calcium ions, which was detected by fura-2 fluorometry. Similar increases were also observed in a calcium-free medium. There was typically a delay of 20 min between NGF infusion and the release of calcium ions, and this delay was longer when NGF was applied at neurite tips. This is probably because NGF must be transported from neurites to the cell body, where calcium ions are released from intracellular stores.

Animals↗
PubMed1991

[Ecological study of the pharyngeal bacterial flora in patients with lung cancer].

We investigated the relationship between changes in pharyngeal bacterial flora and the immunological condition of 10 lung cancer patients before and after anti-cancer chemotherapy. There were significant differences in bacterial flora between normal subjects and patients. However, there were little differences in pharyngeal flora in patients before and after chemotherapy. In 4 out of the 10 lung cancer patients, the ratio of anaerobic bacteria/total bacteria of pharyngeal flora decreased. These 4 cases were in the non-responsive (NC, PD) group of anti-cancer chemotherapy. After administration of anti-cancer drugs, the ratio of anaerobic bacteria increased. No aerobic gram negative rods were isolated at any time during the observation period, because immunological suppression was mild. The results indicate the importance of surveillance for the immunological state of the hosts and changes in pharyngeal bacterial flora.

Adult↗
PubMed1990

Selective growth of sensory nerve fibers on metal oxide pattern in culture.

Metal oxides were used to study how the sensory nerve fibers recognize surface properties. Neurites selectively grow on the metal oxides deposited on silica glass, being guided along the axial direction of the patterns. The guiding ability depends on the electronegativity of the metal in metal oxide. Aluminum oxide or indium oxide patterns showed a remarkable ability to guide the growth direction. Neurites recognize the differences in surface properties (which are reflected by electronegativity) between metal oxides when the metal oxide substrata are only 1 micron in width.

Aluminum↗
PubMed1988

Recognition of artificial microstructures by sensory nerve fibers in culture.

Dissociated culture of adult mouse dorsal root ganglion cells on glass plates, on which grating-associated microstructures (a repetition of microgrooves [mGRV] and microsteps [mSTP] of 0.1-10 micron) are fabricated by the conventional lithographic techniques, represents a remarkable bi-directional growth of their nerve fibers in the axial direction of the grating. Microscopical observation shows that the nerve fibers prefer to grow in the mGRV (70%), while their growth cones exhibit an even distribution onto the mGRV and mSTP. The efficiency of the nerve fibers to grow along the grating-axis are highly sensitive to a fine alteration of the width and depth of the mGRV. The preferential growth of the nerve fibers is thus due to a mechanical recognition of the microstructures by the growth cones and neurites.

Animals↗
PubMed1987

[Evolution of dilated cardiomyopathy from hypertrophic obstructive cardiomyopathy: a case report].

A 20-year-old woman whose echocardiograms showed a rare evolution from hypertrophic to dilated cardiomyopathy during a nine year observation period is described. This patient was initially diagnosed as having hypertrophic obstructive cardiomyopathy (HOCM) at the age of 12 years. Her echocardiogram showed marked thickening of the interventricular septum (IVS) and left ventricular posterior wall (LVPW), asymmetric septal hypertrophy (ASH) and systolic anterior motion of the mitral valve (SAM). Chest radiography revealed a prominent left ventricular border and a cardiothoracic ratio of 0.52. At 18 years of age she experienced onset of palpitation during the 16th week of pregnancy. Her echocardiogram recorded in June 1980 revealed a thickened IVS and LVPW with resolution of the SAM and of the narrow cavity. At 20 years of age she became pregnant again and was admitted to our hospital for the third time at 24 weeks gestation. On admission her blood pressure was 122/60 and her pulse was 56, and moist rales were audible over both lung fields. Peripheral edema was noted. Chest radiography revealed moderate cardiomegaly, a cardiothoracic ratio of 0.66, and congestion of the pulmonary vasculature. An echocardiogram showed thinning of the IVS and LVPW with hypokinesis and dilatation of the cavity compatible with dilated cardiomyopathy (DCM). She delivered a boy on July 15th 1982 at 32 weeks gestation following which she developed marked congestive heart failure. She expired one month later. A chest radiograph made one day before death revealed marked cardiomegaly, a cardiothoracic ratio of 0.76, prominent pulmonary vasculature and a pleural effusion. Autopsy was refused; therefore the terminal DCM-like features were not clarified pathologically. However, the slow progression from HOCM to HCM during eight years and then rapid progression from HCM to DCM during four months was most impressive.

Adult↗