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Biomedical subjects

T Okada

Publications and source records attributed to T Okada.

At least 883 records · Page 49Linked to original sources
PubMed1988

Body temperature monitoring in subjects with delayed sleep phase syndrome.

To clarify the circadian aspects of delayed sleep phase syndrome (DSPS) in 4 patients with DSPS, we recorded polysomnograms and rectal temperature before and after chronotherapy. The time interval (2.7 h) between sleep onset and rectal temperature minimum before chronotherapy was shorter than the time interval after chronotherapy (5.3 h). Before chronotherapy, the period of rectal temperature rhythm was 24.7 h. After chronotherapy, the period of rectal temperature rhythm was 24.0 h. These findings lead to the conclusion that in DSPS there is a weakened mechanism of entrainment similar to that in non-24-hour sleep-wake syndrome.

Adult↗
PubMed1988

Distribution of retinal ganglion cells projecting into the nucleus of the optic tract in rat.

The present study indicates that visual signals responsible for OKN are conducted through the retinal ganglion cells mainly contralaterally, and only in the ventral region of the retina ipsilateral to the injection site. The retinal ganglion cells projecting into the NOT ipsilateral to the injection site were identified as small- and medium-sized cells in the rat. The density of the ventral ganglion cells of the retina contralateral to the injection site was lower than that in any other regions of the retina except for the dorsal region of the retina, and the density of the ventral ganglion cells ipsilateral to the injection site was about 4 times greater than that on the contralateral side. This finding requires physiological investigation in the future.

Animals↗
PubMed1988

Facilitating effect of cold shock on recovery from anoxia-induced contractile depression in isolated rat heart and heart muscle.

The effect of rapid cooling on the recovery process from anoxia-induced hypodynamic state was studied in isolated rat ventricular muscle and ventricle. Following 10-15 minutes' perfusion of N2-saturated Krebs solution, the muscle was reoxygenated. When the muscle was rapidly cooled for 10-30 seconds during the early phase of reoxygenation, the rate of recovery from contracture significantly increased (p less than 0.01). Rapid cooling was also effective on the recovery from contracture induced by superfusion of Krebs solution with lowered sodium chloride concentration, but it did not affect the recovery from rigor induced by CN-. In the recovery from sustained anoxia (60 minutes), cooling facilitated reattainment of tension development and reduction in contracture tension. Similarly, in whole heart, 2-3 episodes of rapid cooling for about 60 seconds significantly accelerated the recovery of pressure development after 30 minutes of anoxia. At 60 minutes after reoxygenation, pressure development in hearts that were reoxygenated without rapid cooling was 29.8 +/- 26.9% (mean +/- SD) of pressure developed before anoxia. This value increased to 93.8 +/- 27.5% following recurrent rapid cooling (p less than 0.001). At the same time, rapid cooling prevented any significant elevation in resting tension (development of oxygen paradox). These results indicate that excess intracellular calcium ions were removed by rapid cooling. This relief of the myocardium from calcium overload is believed to improve mitochondrial function and result in facilitated recovery of contractile activity.

Adenosine Triphosphate↗
PubMed1988

Local anticoagulation without systemic effect using a polymer heparin delivery system.

Polymeric drug delivery systems that allow the application of substances to a localized region for specified periods of time have been developed. A model for intravascular thrombosis in the rat common carotid artery was established using a combination of balloon catheter endothelial injury with 1-hour occlusion of the vessel. After endothelial injury in 11 Sprague-Dawley rats, the adventitial surface of the carotid artery was exposed to the polymer polyvinyl alcohol (PVA) containing heparin and was compared with exposure to PVA alone in the contralateral (control) vessel. Subsequent determinations of the coagulation parameters systemic prothrombin and partial thromboplastin times showed no systemic effect of heparin. All 11 control vessels demonstrated complete or partial thrombosis, whereas only one of 11 heparin/PVA-treated vessels showed a small thrombus. Morphometric analysis of the cross-sectional thrombus: lumen ratio in 10 rats showed a significant reduction (p less than 0.005) in thrombus size for treated vessels (4.1 +/- 9.6%) compared with control vessels (60.2 +/- 25.8%). Scanning electron microscopy verified the absence of thrombus in the treated vessels despite complete endothelial desquamation. In a second group of eight rats, endothelial injury without occlusion did not cause thrombosis in treated or control arteries. The coagulation parameters for this group of eight unoccluded rats were similarly unaffected by heparin/PVA treatment. Our observations suggest that a localized antithrombotic effect of heparin can be achieved without systemic anticoagulation using a polymeric drug delivery system. This technique may be applied to a variety of surgical and nonsurgical clinical conditions.

Animals↗
PubMed1988

Cloning and nucleotide sequence of the brnQ gene, the structural gene for a membrane-associated component of the LIV-II transport system for branched-chain amino acids in Salmonella typhimurium.

The genetically defined gleR-brnQ region responsible for the branched-chain amino acid transport in Salmonella typhimurium was mapped in the 3.3-kilobase SalI-PstI segment of plasmid pOH56 by complementation analysis. By subcloning and genetic recombination analysis, the gleR and brnQ3 mutational sites were localized within the 0.85-kilobase SalI-EcoRV segment, and brnQ4 within the 0.8-kilobase EcoRV-HindIII segment. The nucleotide sequence of the brnQ gene and its flanking regions was determined. The brnQ gene is encoded by the sequence starting 24 base pairs upstream from the EcoRV site. Transcription of the brnQ gene starts at three sites separated by 171, 173 and 174 nucleotides, respectively, from the initiation codon. The promoter sequences can be seen in the immediate upstream region of the transcription initiation sites. There is a long silent region between the transcription initiation sites and a potential Shine-Dalgarno nucleotide sequence. The coding sequence of the brnQ gene, which is 1317 base pairs long, specifies a very hydrophobic protein of 439 amino acid residues.

Amino Acid Sequence↗
PubMed1988

The role of natural killer cells in human tonsillar tissue focussing on the change of tonsillar tissue with aging.

The natural killer (NK) activity of tonsillar lymphocytes is low and NK-cells are small in number. In tonsillar tissue, NK-cells were present in the germinal center, which is where B-cells are located. This suggests that B-cells are related to NK-cells. Judging from the rates of augmentation of NK-activity of INF-alpha, INF-beta, and from the fact that there is no difference in the rate of NK-activity augmentation between tonsillar and peripheral blood lymphocytes with IFN added, it is highly unlikely that there is much difference between the ratios of pre-NK cells and NK-cells. The fact that the NK-activity augmentation in the tonsil rose to approximately double that of peripheral blood on the addition of IL-2 suggests that the percentage of immature NK-cells is high in the tonsil. This supposition is in agreement with the morphological findings. In the infected and child tonsil, it is probable that NK-cells are at an immature stage, that NK-activity is low, that B-cells are active, and that immunoglobulin production is in progress.

Adult↗