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Biomedical subjects

I Tanaka

Publications and source records attributed to I Tanaka.

At least 379 records · Page 21Linked to original sources
PubMed1990

[Effects of sexual difference on the toxicity of ethylene oxide. III. The rat hepatic monooxygenase system].

Wistar male and female rats were exposed to ethylene oxide (EO) at a concentration of 250 ppm, 6 hours a day, 5 days a week for 17 weeks and the effect of EO on the hepatic monooxygenase system in regards to the sex difference was investigated. Serum GOT of the exposed male rat slightly increased, but that of the female did not change. Contents of microsomal protein and cytochrome P-450 of the male exposed group decreased significantly compared to the male control group, but that of the female exposed group did not change. The change of cytochrome b5, protoheme and NADH-ferricyanide reductase activity of the female exposed group was the same as that of the male. Although NADPH-cytochrome c reductase activity of the male exposed group did not change, that of the female group exposed increased significantly when compared to the female control group. From these observations, we concluded that the effect of EO on the hepatic monooxygenase system was different between male and female.

Animals↗
PubMed1990

A passive tobacco smoke exposure system for laboratory animals.

A simple passive tobacco smoke exposure system was developed for laboratory animals. The system consisted of a tobacco smoke generator and an exposure chamber. Performance testing was conducted using Fischer 344 rats. The rats were exposed to passive tobacco smoke generated by 20 cigarettes per day for 3 months. The concentration of the cigarette smoke aerosol (particle phase) in the chamber can be kept almost constant during exposure. The daily average mass concentration was 10.0 +/- 4.3 mg/m3 and the carbon monoxide was 79 +/- 22 ppm during exposure.

Animals↗
PubMed1990

Reconstruction of palate with radial forearm flap; a report of 3 cases.

A prosthesis is the preferred method for the closure of a palatal defect following maxillectomy, with fairly satisfactory results. However, some patients suffer from symptoms due to mismatch of the prosthesis. We have reconstructed palatal defects using radial forearm flaps in 3 cases. The forearm flap is utilised for palatal reconstruction in the double-folded form. The flap is thin and pliable, there are no problems in regard to bulk and drooping of the flap, and the patients can wear the denture with minimal discomfort. We believe that reconstruction of the palate with a forearm flap is a useful procedure, especially for patients suffering from symptoms due to mismatch of the prosthesis.

Female↗
PubMed1990

Reconstruction of penis with free deltoid flap.

Two cases of reconstruction of the penis with a free deltoid flap are described. The urethra was reconstructed with part of the flap and external coverage of the penis was provided with the remainder. In one case an autogenous rib cartilage graft was inserted in the reconstructed penis as a strut. Postoperatively both patients can urinate standing up, and for the one in which a rib cartilage graft was used sexual intercourse is possible. Both cases have good recovery of tactile and protective sensation in their reconstructed penis.

Adult↗
PubMed1990

Comparison between spino-bulbo-spinal and propriospinal reflexes in thalamic cats during stepping.

To analyze changes in the excitability of both the spinal cord and brainstem in thalamic cats stepping on a moving treadmill, we examined the cutaneous propriospinal (PSR) and spino-bulbo-spinal (SBS) reflex responses in 20 adult cats. Tracheal cannulation, spinal transection at the T10 segment, and decerebration at the stereotaxic A12 level were performed under ether anesthesia. Immediately after decerebration, the ether was withdrawn. The head was fixed in a stereotaxic device, the T2 spinal process clamped to a metal frame, and the lumbar region suspended by a hammock, with bilateral forelimb contact on the floor of a treadmill. Electrical stimulation was applied to the superficial radial nerve with a cuff electrode, and two reflex responses (PSR and SBS) were recorded from the biceps brachii muscle in the same forelimb. Shortly before the appearance of forelimb stepping, both PSR and SBS reflex responses were elevated in amplitude. During forelimb stepping, the amplitudes of PSR and SBS reflex responses fluctuated depending on the phase of the step cycle. The PSR response was enhanced in the early phase of the swing, whereas the SBS response was elevated during a wider period from the beginning of the stance to the middle of the swing. The SBS response was completely absent in the late phase of the swing. This period corresponded to the transfer from flexion to extension and the appearance of the EMG of the triceps brachii muscle of the same forelimb. The fluctuation of the SBS response during stepping may be produced at the brainstem level, and not the spinal cord level, because the PSR response was enhanced only during narrow periods. The generation of locomotion thus seems to result in an enhancement of excitability of reflex pathways in the spinal cord and particularly in the brainstem.

Action Potentials↗
PubMed1990

Different responses of cytosolic and mitochondrial glutathione in rat livers after ethylene oxide exposure.

Acute effects of ethylene oxide (EO) at the concentration of 500 and 1500 ppm on glutathione and glutathione reductase of the cytosol and mitochondria in rat liver were examined. The levels of reduced glutathione content and the glutathione reductase activity in the cytosol at 1500 ppm exposure decreased to approximately 10% and 60% of those of control rats, respectively. The decreases in glutathione content and glutathione reductase activity in the mitochondria were less significant than those in the cytosol. Both mitochondrial NADPH-cytochrome c reductase and cytochrome c oxidase activities were only slightly affected by these EO exposures. These results indicate that the change in glutathione content in the cytosol mainly occurred due to the response to EO exposure, and that the mitochondrial glutathione did not serve for such cellular function.

Administration, Inhalation↗
PubMed1990

Simultaneous reconstruction of cervical esophagus and oral cavity with one free jejunal graft.

A case of simultaneous reconstruction of the cervical esophagus and oral cavity with one free jejunal graft is described. A 36-year-old patient had suffered from stricture of the cervical esophagus after reconstruction with a deltopectoral flap and, at the same time, had developed cancer of the anterior floor of the mouth. Both defects were simultaneously reconstructed with one free jejunal graft pedicled on one pair of jejunal vessels. A segment of jejunum was divided into three portions leaving the mesenterium intact. The middle portion was discarded; one portion was used for cervical-esophageal reconstruction and the rest was split longitudinally and used for resurfacing the oral cavity.

Adult↗
PubMed1990

The thermostability of DNA-binding protein HU from bacilli.

The primary and tertiary structures of DNA-binding protein HU from Bacillus stearothermophilus are already known. The primary structure has been previously determined for HU from the closely related B. globigii and the determinations of the sequences from B. caldolyticus and B. subtilis are described here. These bacteria have optimum growth temperatures of greater than 70 degrees C (B. caldolyticus), 65 degrees C (B. stearothermophilus), 37 degrees C (B. subtilis) and 30 degrees C (B. globigii). In vitro measurements from circular dichroic spectra described here give Tm values reflecting these growth temperatures, of 68, 64, 43 and 41 degrees C respectively. We discuss here the relative thermostability of the four proteins in terms of the amino acid differences between the sequences and the three-dimensional model of the B. stearothermophilus HU. The current model for the interaction of the protein with DNA is only discussed in terms of its relevance with regard to thermostability.

Amino Acid Sequence↗
PubMed1990

Inhibition of creatine kinase activity by ethylene oxide.

Exposure of rats to 500 ppm ethylene oxide for six hours a day, three times a week, for 12 weeks, lowered serum creatine kinase activity by more than 40%. The only other change was a slightly decreased triglyceride concentration. After four weeks of exposure, neither aspartate aminotransferase nor lactate dehydrogenase activity in brain, spinal cord, and muscle was affected but creatine kinase activity was clearly inhibited. In vitro, ethylene oxide inhibited creatine kinase activity in brain homogenate and in a purified muscle enzyme preparation. Dithiothreitol did not counteract the effect of ethylene oxide. Though the amount of sulphydryl groups in purified creatine kinase was decreased considerably by exposure to ethylene oxide, the enzyme still showed moderate activity. Thus ethylene oxide inhibits creatine kinase activity in vivo and in vitro and the inhibition appears to be unrelated to the disruption of sulphydryl groups in the enzyme.

Animals↗
PubMed1990

Effects of repetitive administration of corticotropin-releasing hormone combined with lysine vasopressin on plasma adrenocorticotropin and cortisol levels in secondary adrenocortical insufficiency.

To examine the functioning of the hypothalamo-pituitary-adrenocortical axis in secondary adrenocortical insufficiency, we administered 100 micrograms synthetic human CRH, iv, plus 10 U lysine-8-vasopressin (LVP), im, three times daily for 3 consecutive days. The changes in plasma ACTH and cortisol levels during the administration and the response to an insulin tolerance test (ITT) conducted before and after the administration were determined. In three patients with isolated ACTH deficiency, basal plasma ACTH and cortisol levels were undetectablly low, and there was no response noted in the ITT or during CRH-LVP administration throughout the observation period. In four patients with adrenocortical insufficiency who had undergone successful transsphenoidal microadenomectomy for Cushing's disease and in six patients who had undergone curative unilateral adrenalectomy for Cushing's syndrome, basal plasma ACTH levels were low, but responded considerably to both stimulation tests. Along with the 3 days of CRH-LVP stimulation, however, neither the peak nor the time-integrated ACTH response was significantly enhanced, because of the variability of the responses among the patients. Compared with the ACTH response on the last day of CRH-LVP stimulation, the subsequent ITT tended to induce a lower ACTH response in the post-Cushing's disease patients and a higher response in the post-Cushing's syndrome patients. Regarding the plasma cortisol levels, the basal, peak, and integrated responses tended to increase daily during CRH-LVP administration. Conversely, the ITT after repetitive CRH-LVP administration induced a higher cortisol response than the test before CRH-LVP administration in the post-Cushing's disease patients. No serious complications were noted in any of the patients during or after the treatment. The present findings indicate that 1) repetitive administration of CRH in combination with LVP is a safe and valuable provocation test to examine the pituitary ACTH reserve and the integrity of the pituitary-adrenocortical axis; 2) isolated ACTH deficiency is usually due to a defect at the pituitary level; 3) with respect to adrenocortical responsiveness, post-Cushing's disease patients show a better accumulation of the provocative effect than do post-Cushing's syndrome patients; and 4) both hypothalamic and pituitary dysfunction are responsible for adrenal hypofunction in patients after hypercortisolemia, but post-Cushing's syndrome patients (especially those with a short period of hypercortisolemia) appeared to have less impairment of hypothalamic ACTH-releasing activity than post-Cushing's disease patients.

Adrenal Cortex↗
PubMed1990

Alterations in Na(+)-K(+)-ATPase activity and beta-endorphin content in acute ischemic brain with and without naloxone treatment.

The Na(+)-K(+)-adenosine triphosphatase (Na(+)-K(+)-ATPase) activity and beta-endorphin immunoreactivity were determined in rat brain at the acute stage of ischemia produced by unilateral occlusion of the middle cerebral artery (MCA). The effect of pretreatment with naloxone on these activities was also evaluated in the same model. After MCA occlusion, Na(+)-K(+)-ATPase activity was promptly reduced in the ischemic hemisphere and remained at a lower level than in the contralateral hemisphere during 90 minutes of ischemia. A single intraperitoneal 0.5-mg injection of naloxone prior to MCA occlusion attenuated the inactivation. On the other hand, beta-endorphin immunoreactivity was significantly increased following ischemia. The increase was marked in the ischemic hemisphere and was also observed in the contralateral hemisphere; this increase was not affected by the administration of naloxone. These results indicate the possibility that naloxone contributes to protecting the brain from ischemia through stabilizing the cellular membrane. The possible mechanism by which naloxone attenuates the inactivation of Na(+)-K(+)-ATPase in the ischemic brain is discussed in view of alterations of the central beta-endorphin system during ischemia.

Acute Disease↗
PubMed1990

[Adenomyoma in association with early gastric carcinoma].

Described is a gastric adenomyoma associated with superficial gastric adenocarcinoma that was found in a 72-year-old male. This uncommon benign gastric lesion is believed to be developmental in origin and sometimes categorized as belonging to a subgroup of a heterotopic pancreas. Besides its rarity, an adenomyoma is also known to be a possible cause of a gastric malignancy. Although the focus of the carcinoma in our case was located in the center of the adenomyoma, this finding cannot support the etiology of a gastric carcinoma originating in an adenomyoma. However, the present case appears to imply some relationship between an adenomyoma and a gastric carcinoma.

Adenocarcinoma↗
PubMed1989

Thermal desorption of organic solvent from activated carbon for determination of vapor concentration in work environment.

A thermal desorption method is proposed for the measurement of single- and bi-component organic solvents adsorbed on activated carbon. The adsorbed amount was obtained from the measured desorbed amount and the estimated thermal desorption efficiency. Two estimation methods are proposed to determine the desorption efficiency. One is a numerical method, and the other is a simplified analytical method. The numerical method is generally more accurate than the simplified method in estimating the desorption curve and the desorption efficiency, but much time is needed for calculating. By the simplified method, the desorption efficiency could be estimated quickly by using a personal computer. The estimated desorption efficiencies determined by the two methods are compared with the experimental values. A determination procedure of the adsorbed amount by the proposed method is described.

Absorption↗