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Biomedical subjects

M Miyamoto

Publications and source records attributed to M Miyamoto.

At least 415 records · Page 23Linked to original sources
PubMed1989

Influence of dietary cis and trans fats on DMH-induced colon tumors, steroid excretion, and eicosanoid production in rats prone to colon cancer.

The effect of geometrical isomerism of dietary fats on colon tumorigenesis was studied in male and female rats of a strain prone to colon cancer (Wistar-Furth-Osaka). The rats were fed purified diets containing either partially hydrogenated corn oil (trans fat) or high-oleic safflower (cis fat) at the 5% level for one week and received a single oral dose of 1,2-dimethylhydrazine. The difference in the fatty acid composition of dietary fats was confined solely to the geometry of octadecenoate. An appropriate level of linoleic acid (2% of total energy) was supplied. After about 60 weeks, neither fat-type nor sex-dependent differences in the incidence of colon and small intestinal tumors was observed. The fecal excretion of neutral but not acidic steroids was higher in male rats fed the trans fat than in those fed the cis fat, but the composition remained almost unchanged. Aortic production of prostacyclin and the plasma concentration of thromboxane B2 were not influenced by dietary fats, although these were significantly higher in females, irregardless of the fat source. Thus, trans fat behaved much like the cis fat in various parameters, except for steroid excretion.

Animals↗
PubMed1989

Leukocyte-poor platelet concentrates at the bedside by filtration through Sepacell-PL.

We developed a new filter, 'Sepacell-PL', consisting of a blood administration set for the preparation of leukocyte-poor platelet concentrates at the patient's bedside. This filter is packed with 1.8 microns polyester fibers coated with a new polymer, and has a volume of 14 ml. Sepacell-PL removed more than 99% of the leukocytes while approximately 93% of platelets were recovered from 10 units of platelet concentrates which contained 5 x 10(8) leukocytes and 3 x 10(11) platelets. The functions of pre- and postfiltrated platelets were unchanged. The filtration procedure is very simple, without priming with saline to remove air and wet the filter. Moreover, platelet concentrates can be passed through the filter at a flow rate of 4 ml/min, or at a higher flow rate of 54 ml/min by gravity.

Blood Transfusion↗
PubMed1989

Paraventricular stimulation with glutamate elicits bradycardia and pituitary responses.

The excitatory neurotransmitter, L-glutamate (0.5 M, pH 7.4), or the organic acid, acetate (0.5 M, pH 7.4), was microinjected (50 nl over 2 min) directly into the paraventricular nuclei (PVN) of pentobarbital sodium-anesthetized rats while arterial blood pressure and heart rate and plasma adrenocorticotropic hormone (ACTH), vasopressin, and oxytocin were measured. Activation of PVN neurons with L-glutamate led to increases in plasma ACTH, vasopressin, and oxytocin and a profound bradycardia (approximately 80 beats/min) with little change in arterial blood pressure. Microinjection of acetate had no effect on the above variables. The decrease in heart rate was shown to be dependent on the concentration of glutamate injected and the volume of injectate. The bradycardia was mediated through the autonomic nervous system because ganglionic blockade (pentolinium tartrate) eliminated the response; atropine and propranolol severely attenuated the bradycardia. The bradycardia was greatest when L-glutamate was microinjected into the caudal PVN. Injections into the rostral PVN or into nuclei surrounding the PVN led to small or nonsignificant decreases in heart rate. Focal electric stimulation (2-50 microA) of the PVN also led to decreases in heart rate and arterial blood pressure. These data suggest that activation of PVN neurons leads to the release of ACTH, vasopressin, and oxytocin from the pituitary and a bradycardia that is mediated by the autonomic nervous system.

Adrenocorticotropic Hormone↗
PubMed1989

Inner medullary blood flow in postischemic acute renal failure in the rat.

To study the effect of renal ischemia on the circulation in the inner medulla, blood flow in descending and ascending vasa recta was determined by fluorescence videomicroscopy in the exposed papilla of the uninephrectomized rat after clamping of the renal artery for 45 min. Total renal blood flow was determined in parallel studies with an electromagnetic flowmeter. Animals were studied 90 min (group 1E) and 24 h (group 2E) after right nephrectomy and release of the left renal artery clamp. Control rats were studied 90 min (group 1C) and 24 h (group 2C) after right nephrectomy alone. In groups 1E and 2E, total renal blood flow was reduced to 70 and 80% of that in their respective controls; renal vascular resistance increased by 50 and 73%, respectively. In striking contrast, blood flow was markedly elevated in descending and ascending vasa recta in groups 1E and 2E compared with the values in their respective uninephrectomized controls. These results indicate that the circulation in the inner medulla is rapidly restored after 45 min of total renal ischemia and that vasa recta blood flow rises above normal after 90 min and 24 h, despite a reduction in total renal blood flow and an increase in renal vascular resistance.

Acute Kidney Injury↗
PubMed1989

Long-term inhibition of angiotensin converting enzyme suppresses calcium channel agonist-induced contraction of aorta in hypertensive rats.

To elucidate functional changes in the vascular smooth muscle of spontaneously hypertensive rats (SHR) after chronic inhibition of angiotensin converting enzyme, we examined the contractile responses to different pharmacological interventions in the isolated aortas from SHR treated with a novel angiotensin converting enzyme inhibitor, CS-622 (10 mg/kg/day) for 20 weeks. In normal K+ medium, a marked contraction was elicited by increasing Ca2+ concentration from 0 to 3 mM in aortas from a control group of SHR, but not in aortas from SHR treated with CS-622. In 60 mM K+ medium, however, the sensitivity of aorta to Ca2+ was almost the same in the two groups. A calcium channel activator, CGP-28392 (10(-7) to 10(-6) M), induced a marked contraction in the aortas from control SHR, but not in the aortas from CS-622-treated SHR. When slightly depolarized in 10 or 12 mM K+ solution, the aortas from CS-622-treated SHR contracted in response to CGP-28392. The aortic sensitivity to KCl contraction was much lower in CS-622-treated SHR than in untreated SHR, whereas the sensitivity to phenylephrine contraction was little different in the two groups. These contractile profiles of aortas from CS-622-treated SHR were very similar to those from normotensive Wistar-Kyoto rats but not to those from hydralazine-treated SHR. These data suggest that contractions due to Ca2+ through voltage-dependent calcium channels are exaggerated in SHR aorta and that long-term treatment with angiotensin converting enzyme inhibitor suppresses the abnormal contractility of SHR vascular smooth muscle, probably through alterations of voltage-related functions of calcium channels.

Animals↗
PubMed1989

Body surface potential mapping in anterior myocardial infarction--a longitudinal study in acute, convalescent and chronic phases.

Body surface potential mapping (BSPM) was performed to evaluate the infarct size and the viability of myocardium in the infarct area in 20 patients with anterior myocardial infarction (MI). BSPM was performed at the early acute phase, 1 week, 1 month and 2 months after onset of the symptoms. The departure areas were obtained according to the potential distribution below the mean normal range and were compared with the value for creatine phosphokinase (CPK), hemodynamic parameters, ejection fraction measured by radionuclide ventriculography, extent score (ES) and severity score (SS) of thallium-201 single photon emission computed tomogram. Two months after the infarction, the ergometer exercise was performed and departure areas before and after exercise were compared. With the departure map technique, the departure areas in all cases were found in the anterior region of the thorax; From 1 week to 2 months after MI, the departure areas were significantly reduced. One week after MI, the departure areas had a positive significant relation with peak CPK and sigma CPK. One month after MI the departure areas also had a positive relation with ES or SS. One week and 1 month after MI, the departure areas had a negative relation with the left ventricular stroke work index or the left ventricular ejection fraction. After exercise test in the chronic phase, the departure areas were significantly enlarged. In conclusion, the departure map is useful in evaluating the location, sequential changes of size of anterior MI including the ischemic area around the infarct site and the left ventricular function. It is suggested that the enlarged departure areas after exercise might be the ischemic areas provoked by exercise.

Adult↗
PubMed1989

[Ameliorating effects of idebenone and indeloxazine hydrochloride on impairment of radial maze learning in cerebral embolized rats].

The ameliorating effects of idebenone and indeloxazine hydrochloride on the impairment of memory and learning were studied in cerebral embolized rats. The embolized rats had impaired memory and learning ability in the radial maze task; these were demonstrated by a decrease in correct responses and an increase in total errors. In particular, the rats showed severe impairment of working memory, as shown by a marked increase in the numbers of re-entries into the arm that had been already visited. Idebenone (30 mg/kg, p.o.) exerted marked ameliorating effects on the impairment in the embolized rats: the drug significantly increased the correct responses and decreased the errors. Indeloxazine hydrochloride also improved the memory impairment in the embolized rats, as shown by a reduction of the errors. The ameliorating effects of these drugs may be due mainly to improvement of hypofunctions of the central nervous system. These results confirm that idebenone and indeloxazine hydrochloride may have ameliorating actions on impairment of memory and learning induced by brain hypofunction, and they suggest that the action of idebenone is more potent than that of indeloxazine hydrochloride.

Animals↗
PubMed1989

Beneficial renal effects of CS-905, a novel dihydropyridine calcium blocker, in SHR.

CS-905 is a potent dihydropyridine calcium blocker that has a gradual and long-lasting antihypertensive action with little tachycardia in SHR. In this study, we investigated chronic and acute effects of CS-905 on renal functions in SHR. To examine the chronic effects, 23 week-old male SHR were treated with CS-905 (1 or 3 mg/kg/day, p.o.) or 0.3% CMC (carboxymethylcellulose). After the 15 week-treatment, the agent dose-relatedly lowered systolic blood pressure measured 24 hr after the final administration (184 +/- 2 and 173 +/- 3 mmHg at 1 and 3 mg/kg/day vs. 218 +/- 4 mmHg for the control group). Natriuresis and the reduction of urinary protein excretion were also observed in the CS-905 treated groups. Urinary NAG (N-acetyl-beta-D-glucosaminidase) activity tended to decrease, but not significantly. Histopathological changes observed in the SHR kidney were reduced by chronic treatment with CS-905. On a single oral administration in 38 week-old SHR, CS-905 caused natriuresis at a dose of 3 mg/kg, but did not affect urinary protein excretion and urinary NAG activity. These effects of CS-905 on renal functions may be beneficial in the treatment of hypertension.

Acetylglucosaminidase↗
PubMed1989

Antihypertensive effects of CS-905, a novel dihydropyridine Ca++ channel blocker.

CS-905 is a novel dihydropyridine calcium blocker. A single oral administration of CS-905 or nicardipine at doses of 0.3-3.0 mg/kg produced a dose-dependent reduction of blood pressure in conscious SHR. CS-905, when administered orally in conscious SHR, was more than 3 times as potent as nicardipine. Unlike the hypotensive effect of nicardipine, that of CS-905 has a gradual onset and is long-lasting, with little increase in heart rate. An intravenous administration of CS-905 also produced a hypotension with a slow onset and long duration in SHR, but CS-905 was 3 times less potent than nicardipine by intravenous administration. This difference may be attributed to the first pass effect, which was associated with nicardipine but not with CS-905. The blood pressure lowering effects of CS-905 was most potent in DOCA-salt hypertensive rats, followed by SHR, RHR and normotensive rats, in this order. CS-905 is expected to be an antihypertensive agent that is effective on a once a day regimen in clinical settings.

Anesthesia↗
PubMed1989

[A study of bronchial sensitivity and bronchial reactivity using Astograph and transcutaneous oxygen tension in asthmatic children. The problems of simultaneous measurement].

Bronchial sensitivity and reactivity in 60 patients with bronchial asthma was measured using the Astograph and simultaneous transcutaneous oxygen tension [PtcO2]. In spite of increasing respiratory resistance, there were some cases in which PtcO2 did not show remarkable decrease. The PtcO2 percentage was defined as (basal value of PtcO2 - bottom value of PtcO2)/(basal value of PtcO2). The correlation between PtcO2% and the basal value of PtcO2 was relatively high (r = 0.42, n = 58, p less than 0.005). The correlation between PtcO2% and V50/Ht or V25/Ht was also relatively high (r = 0.41, n = 45, p less than 0.01, r = 0.49, n = 45, p less than 0.001, respectively). In some cases of small airway obstruction or low basal value of PtcO2, was smaller. The patients of over 70% in FEV1.0/VCP were in accord with that of over 70 mmHg in the basal value of PtcO2. The results suggest the recommended basal value of PtcO2 to measure bronchial sensitivity and reactivity may be over 70 mmHg.

Adolescent↗
PubMed1989

A study on colon cancer-prone rats of WF-Osaka strain.

We have established a colon cancer-prone substrain in WF strain rats strictly bred by sister x brother mating for more than 20 years. Colon carcinomas were located only in the ascending colon with no remote metastases. Each incidence of colon carcinoma varied from 30 to 40% in the respective investigation. There was no apparent sex difference. Approximately 9% of colon carcinomas were associated with gastric carcinoma in the prepyloric region and they died within four months of age due to malnutrition and intestinal bleeding. There were a few cases of carcinomas of the terminal ileum and the rectum. All of these carcinomas from three different portions showed histologically well differentiated tubular adenocarcinoma. It was found that about 40% of colon carcinomas showed spontaneous regression in the period from four to twelve months old. We have also succeeded in establishing two lines of the transplantable colon carcinoma (C1 and C2) and the transplantable gastric carcinoma (S1 and S3) from those of spontaneous colon carcinomas and gastric carcinomas. Then recipient female rats inoculated intraperitoneally with these transplantable carcinomas newly developed adenocarcinomas of the corpus uteri, which had never been found in the rats of this strain. In addition, the transplantable tumor line of adenocarcinoma of the corpus uteri was also established (U2). When transplanted these tumors intraperitoneally (S1, S3, C1, C2 and U2), male and female recipient rats extremely increased in the incidence of carcinomas of the stomach and the colon. As far as female recipient rats were concerned, a large number of carcinomas of the corpus uteri were also found regardless of the derivation of tumors. We believe that the established colon cancer-prone rat strain (WF-Osaka) as well as those of transplantable tumor lines will open a further research fields and will be available as an animal model of colon cancer for human beings.

Adenocarcinoma↗
PubMed1989

Spontaneous colon cancer and its spontaneous regression in highly inbred Wistar Furth rats: genetic analysis.

The incidence of spontaneously occurring colon cancer and its spontaneous regression in the highly inbred Wistar Furth (WF) rat was studied using 1346 rats from the 19th to the 21st inbreeding generation. A statistical analysis revealed a positive phenotypical correlation between parents and offspring concerning the incidence of colon cancer and its spontaneous regression. The incidences of cancer-bearing offspring born from the crosses of cancer-free dams and cancer-bearing, spontaneous regression and cancer-free sires were 21%, 14.1% and 22.7%, respectively, and these results manifested a statistically significant difference. The incidences of spontaneous regression in the male offspring born from the same crosses mentioned above were 35%, 46.8% and 23.5%, respectively; they also represented a significant difference. Based on the analysis, two independent genetic factors, one carcinogenic and the another regressive, were suggested to determine the phenotypes of offspring. The cancer-bearing offspring have the carcinogenic factor but not the regressive factor, while the spontaneous regression ones have both factors. The frequencies of the carcinogenic and the regressive factors in male rats were estimated to be 54.1% and 59.8%, respectively, on average from the 19th to the 21st generation. A genetic pool of the carcinogenic and the regressive factors was established in the WF rat.

Animals↗
PubMed1989

Morphology on spontaneous regression of the autochthonous colon carcinoma in WF Osaka rat strain.

In order to study the spontaneous regression of the colon cancers of WF Osaka strain rats, laparotomies were carried on 701 rats in sequence at the age of four months. Among them, 260 cases were found having colon cancers at the laparotomy. 107 out of them showed spontaneous regression of the colon cancer in the ascending colon. Most of the cases which spontaneously regressed were rather the early stage (stage 1 and 2) of the colon cancer, though 26 cases of advanced cancer also showed spontaneous regression. Grossly the lesions of the spontaneous regression were those of thickened, elongated ascending colon, with occasional dilation. Some cases showed the cystic formation at the portion of former lesions. There was a case which showed normal appearance of the ascending colon with regional lymph node metastasis measuring 1.5 x 1.5 centimeters. Histological appearance was varied showing reconstruction of the muscular layer and mucularis mucosae. Mucosal epithelium was almost normal looking, but glandular arrangement showed cystic dilation. The ectopic existence of glandular composition was seen in the restored lesion in the muscular layer. Macrophage infiltration was indispensably main histological reaction with central necrosis of formerly existed cancer cells, which was considered to be cellular immunity against cancer cells, or exogenous substances, such as viruses in cancer cells.

Animals↗
PubMed1989

Morphology on the transplantable gastric carcinoma in WF Osaka rat strain.

We have established four lines of transplantable gastric carcinoma in WF Osaka rats. They were derived from adenocarcinomas of the glandular stomach, which were developed along with the lesser curvature, measuring less than 1.0 square centimeter. Morphology of these four lines of the transplantable tumor showed essentially an identical figure in their respective generations. Histology in the early generation of transplanted tumors showed well differentiated tubular adenocarcinoma similar to the primary lesion of the stomach. Later the histological appearance of these four lines of the transplanted tumor altered from glandular structure to keratinizing squamous cell metaplasia of cancer cells. The lines of S4 and S5 transplantable tumor were recently established, but the lines of S1 and S3 transplantable tumor have been transplanted as far as more than the 60th generation, and changed their histological appearance to scirrhous carcinoma in the line of S1 and medullary carcinoma in the line of S3. The growth speed of S1 line became slow in the later generations compared to the former ones, and that of S3 line became extremely rapid and recipient rats died with cachexia within two weeks. Effectual activities of tumor enhancement for the gastric and the colon cancer, previously reported elsewhere, recently decreased, and gastric carcinoma was rarely induced by these two lines. Lately established S4 and S5 transplantable tumor lines showed vigorous flourish of inducing gastric and colon cancers.

Adenocarcinoma↗
PubMed1989

Pathology of adenocarcinoma of the corpus uteri induced by inoculation with transplantable carcinomas of the stomach, the colon and the corpus uteri in Wistar-Furth Osaka rat strain.

Among 659 female recipient rats inoculated with the transplantable carcinomas of the stomach (S1 and S3), the colon (C1 and C2) and the corpus uteri (U2) in the same strain of Wistar-Furth Osaka (WF Osaka) rats, 160 adenocarcinomas of the corpus uteri were found. 79 cases of them were grossly diagnosed as carcinomas, because the uteri were tremendously enlarged and kinking in the peritoneal cavity. The rest of them were confirmed to be carcinomas histologically. They were all well differentiated tubular adenocarcinomas with some papillary growth in the uterine cavity. Only one case showed to be an invasive carcinoma. Average age of female rats at the time of inoculation was 42 days after birth, and the uterine carcinomas were found in 34 days in average thereafter. Such carcinomas of the corpus uteri in young adolescent female rats have not been seen, excluded the cases inoculated with those transplantable tumors mentioned above into the peritoneal cavity on this WF Osaka rat strain. Therefore, it was thought that each transplantable carcinoma had played an important role for the induction of the adenocarcinoma of the corpus uteri.

Adenocarcinoma↗
PubMed1989

[The effect of pulsatile perfusion on aortocoronary bypass grafting].

To evaluate the effect of pulsatile perfusion on myocardial protection and peripheral circulation, 23 patients undergoing aortocoronary bypass grafting were studied by dividing two groups; one with pulsatile perfusion technique (11 patients) and the other with non-pulsatile (12 patients). The cardiac functional assessments were made on CI, LVSWI, PCWP, CVP at 3, 6, 12 and 24 hours after the operation and the enzyme (CPK, CPK-MB, LDH, GOT) sampling were performed on 1, 2, 4 and 7 days after the operation. The difference between esophageal and rectal temperature, and urine output during cardiopulmonary bypass, indicating the peripheral circulation, were also measured. From these clinical results, it is concluded that pulsatile perfusion method is to be beneficial in myocardial protection and peripheral circulation during operation of aortocoronary bypass grafting.

Adult↗
PubMed1989

[Combination therapy with etoposide, adriamycin and cisplatin in advanced primary and recurrent gastric cancer].

Fourteen patients with advanced gastric cancer consisting of seven primary cases and seven recurrent cases were treated with the combination of etoposide, adriamycin and cisplatin (EAP). One of the primary cases (14%) and three of the recurrent cases (43%) responded to the therapy, but a high incidence of toxicities including leukopenia, thrombocytopenia, alopecia, nausea and vomiting was observed. It is concluded that EAP therapy can be useful in the treatment of advanced gastric cancer if countermeasures to the toxicities of these drugs are considered.

Adenocarcinoma↗