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Biomedical subjects

T Toyoshima

Publications and source records attributed to T Toyoshima.

At least 73 records · Page 4Linked to original sources
PubMed1989

[Management of pacemaker patients by bathtub ECG].

We evaluated the efficacy of a new method for recording electrocardiogram (ECG) of pacemaker patients in bathtub (bathtub ECG). ECG from the pacemaker implanted patients in the bathtub with tap water was recorded through three silver/silver chloride electrodes (4 x 4 cm) fitted on the inside wall of bathtub. Electric signal was connected to the isolated amplifier and recorded on the strip chart recorder. Contrast to the conventional method for recording standard ECG, bathtub ECG does not require body surface electrodes and is recorded at patients home. Although the amplitude of bathtub ECG was reduced approximately to a quarter of standard ECG, cardiac arrhythmia can be easily interpreted by bathtub ECG. In patients with pacemaker system, the amplitude of the pacing pulse recorded by bathtub ECG was much larger than that of QRS complex recorded by standard ECG. Therefore, we conclude that bathtub ECG would be a suitable method to follow up patients with pacemaker system.

Baths↗
PubMed1989

[Assessment of sensing parameters in the rate responsive cardiac pacemaker].

Rate responsive cardiac pacemakers in which pacing rate is adjusted by hemodynamic and metabolic demands have been developed in recent years. Although different parameters such as body activity, QT interval, respiration rate, body temperature are used to presume metabolic demand, it is suspected that no single parameter can provide accurate estimate of metabolic demand, and hence rate responsive pacemaker by combined parameters is proposed. This study is aimed to investigate physiological parameters during exercise so as to obtain reliable pacing control algorithm. Twenty healthy volunteers were assessed by a traded treadmill exercise according to the Bruce protocol, and hart rate, QT interval, body temperatures (forehead deep body temperature, rectal, tympanic, oral and axillary temperatures) and respiration rate were monitored. The results showed that correlation coefficient between heart rate and QT interval was 0.979, and that between hart rate and respiration rate was 0.969. Hysteresis was observed when these parameters were plotted against hart rate through a whole exercise protocol.

Body Temperature↗
PubMed1987

The fibers which leave the Probst's longitudinal bundle seen in the brain of an acallosal mouse: a study with the horseradish peroxidase technique.

The congenital absence of the corpus callosum, a brain anomaly frequently noted in humans, has been recently found to occur in some mice of the ddN strain in our laboratory. In the brains of these mice, the Probst's longitudinal bundle is always present on both cerebral hemispheres and gives rise to some aberrant fibers toward the midline. In this research, the neuroanatomical features of these fibers were studied by iontophoretical injections of horseradish peroxidase (HRP) into the neocortex of acallosal mouse brains. The results revealed that the fibers which leave the Probst's longitudinal bundle are, at least, of 3 kinds: namely, the fibers that run out from the anterior portion of the bundle and take a U-turn ipsilaterally without crossing the midline through the septal tissue to go back again into the longitudinal bundle at the level where they have left it; the commissural fibers that leave the bundle from its middle portion and cross through a tiny bridge of tissue associated with the ventral hippocampal commissure to the opposite hemisphere; and the fibers that arise from the posterior portion of the bundle and accumulate as an anomalous fascicle below the cingulum. The observation that no labeled fibers were seen within the anterior commissure in the present HRP materials suggests that the axons from neocortex which are prevented from crossing the midline in mice with congenital absence of the corpus callosum cannot find an alternative pathway via the anterior commissure.

Agenesis of Corpus Callosum↗
PubMed1987

Twenty-four hour monitoring of deep body temperature with a novel flexible probe.

A portable thermomemory unit with a light, thin and flexible probe has been developed for the measurement of whole-day variations in deep body temperature. The probe consists of a thermistor, a heat-flow sensor and a heater. The probe detects heat flow from the skin; the heater then compensates for the heat lost and consequently the skin is effectively insulated from the ambient microenvironment. Skin temperature beneath the probe is therefore determined by the deep body temperature. The probe is 46 mm in diameter and 3 mm thick, its weight is 5 g. The probe is light and flexible and makes close contact with the skin. A 2 kbyte RAM in the unit enables up to 34 h of data to be collected with a sampling rate of once per minute. The device was applied to the chest and abdominal walls, and to the calf; the chest and abdominal deep body temperatures showed a significant dual phase diurnal variation, usually being low during sleep. In contrast, the calf showed a dynamic deep body temperature variation which depended on the amount of leg exercise. The device was found to be effective for analysing daily variations; measurements on the limbs suggested that it could be used for monitoring peripheral circulatory disorders.

Biomedical Engineering↗
PubMed1987

[Effects of chelating reagents on the hippocampal EEG and histochemical Timm staining pattern in a mouse brain].

A series of experiments we examined in detail the effects of four chelating reagents, dithizone, DEDTC, oxine and EDTA, upon (1) Timm's staining in the hippocampal formation, (2) brain electrical activity recorded from hippocampal and cortical electrodes, (3) recovery effect with zinc acetate or zinc sulfate on abolished brain electrical activity, (4) open field activity, (5) toxicity, (6) and heart rate. Dithizone, DEDTC and oxine influenced all measures, and the degree of effect varied directory with dose. But EDTA has not any significant effect on biological system. Resulting data were summarized in Table 4.

Animals↗
PubMed1986

Differential effects of kainic-acid-induced hippocampal lesions on the acquisition of the jump-box avoidance task in mice.

This research examined the effects of kainic-acid (KA)-induced hippocampal lesions on the acquisition of a jump-box avoidance task in mice. When the hippocampal lesion was unilateral, mice with lesions in the lateral portion of the CA1 region showed deficits in acquisition while those with lesions in the CA3 region and/or the medial portion of the CA1 region did not. When the hippocampal lesion was bilateral, on the other hand, mice with lesions in the CA3 region and/or the lateral portion of the CA1 region were deficient in acquisition while those with lesions in the medial portion of the CA1 region were not. Among the mice with various KA-induced hippocampal lesions avoidance responses were not correlated with the level of open field activity, indicating that acquisition differences observed are not dependent upon, nor secondary to, levels of spontaneous activity. These results strongly suggest that there exist regional differences in the involvement of hippocampal pyramidal cell layers in acquisition of the jump-box avoidance task: both the CA3 region and the lateral portion of the CA1 region are involved in acquisition, while the medial portion of the CA1 region is not.

Animals↗
PubMed1984

Agenesis of the corpus callosum in ddN strain mouse associated with unusual facial appearance (flat-face).

In the course of an experiment involving brother-sister matings between ddN strain mice, mice occurred with an unusual facial appearance (flat-face). Subsequently, 4 mice with flat-face were bred from the litters of the second birth (ca. 10% frequency). This flat-face was assumed to be the result of a malformed short nose, hypoplastic maxilla and mandible, and hypertelorism. These 4 flat-face mice exhibited no significant delays in growth, motor ability or the development of learning ability. Histologically, they were all characterized by an almost total absence of callosal fibers and the presence of abnormal longitudinal neuromatous bundles. Therefore, the flat-face mice may be useful as experimental animals for brain research, as one can easily judge that they lack the corpus callosum from the facial appearance.

Abnormalities, Multiple↗