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Biomedical subjects

S Imai

Publications and source records attributed to S Imai.

At least 703 records · Page 39Linked to original sources
PubMed1982

Mammary tumor induction in inbred mouse strains with urethane is not accompanied by changes in expression of B- and C-type retroviral structural proteins.

Urethane administrated in the drinking water of breeding female mice of five inbred strains (DDf, KF, C3Hf, ddY and C57BL) leads to a higher incidence of mammary tumors at an extremely early age in four of these strains (DDf, KF, C3Hf and ddY). In the case of the DDf strain the tumors are adenoacanthomas, but in the case of the other strains adenocarcinomas are also observed. The effect of urethane in the drinking water on expression of endogenous retroviral structural proteins of the B and C type (MTV and MuLV) was studied in the milk by an immunodiffusion test and in organ extracts by radioimmunoassays (for MTVp27, MTVgp52 and MuLVp30). Organs tested include salivary glands, thymus and spleen from female and male animals. In addition, prostate and seminal vesicles were tested in male animals and uterus and mammary glands in females. Mammary tumors induced by urethane were also treated. Urethane does not induce or enhance endogenous retroviral antigen expression, either in these organs or in the mammary gland, one of the target organs for tumorigenesis by this agent.

Adenocarcinoma↗
PubMed1982

Comparison of mammary tumorigenesis between litters in relation to mammary tumor virus antigenic expression in the milk of C3H/He mice.

As a possible step to estimate the relationship between mammary tumor virus (MTV) and mammary tumorigenesis in mice, MTV antigenic expression in mother's milk and spontaneous mammary tumorigenesis in their daughters were compared between the 1st, the 2nd and the 3rd litters of the highly inbred strains of C3H/H3 mice with low mammary tumor incidence. While MTV antigenic expression was detected in all undiluted samples at each litter by immunodiffusion test, the amount of antigen as measured by the single radial immunodiffusion method was increased with increasing litter numbers. On the other hand, the development of preneoplastic mammary hyperplastic alveolar nodules was different little between litters and mammary tumor incidence by 13 months of age was very low with no difference in all litters. The pattern of estrous cycles and plasma prolactin level were also similar in each litter. The results suggest that spontaneous mammary tumorigenesis in mice is not always affected quantitatively by the amount of MTV when endocrine and genetical conditions are similar.

Animals↗
PubMed1982

Alcohol dehydrogenase isozymes in the mouse: genetic regulation, allelic variation among inbred strains and sex differences of liver and kidney A2 isozyme activity.

Genetic analysis of a proposed cis-acting temporal locus (Adh-3t), which regulates alcohol dehydrogenase C2 (ADH-C2) activity in mouse epididymis extracts, among F1 (ddN X BALB/c) X ddN male backcross progeny provided evidence for genetic distinctness between the structural (Adh-3) and temporal (Adh-3t) loci on chromosome 3. Genetic analysis also confirmed the close linkage of Adh-1 (encoding liver and kidney ADH-A2) and Adh-3 (encoding stomach ADH-C2) to within 0.3 centimorgans on the mouse genome. Evidence is presented for a proposed closely linked cis-acting temporal locus (designated Adh-lt) for the A2 isozyme (encoded by Adh-1) controlling the activity of this enzyme in mouse kidney extracts, but having no apparent affect on liver and intestine ADH-A2 activities. An extensive survey of the distribution of Adh-1, Adh-3 and Adh-3t alleles among 65 strains of mice is reported--with the exception of two Japanese strains (ddN and KF), linkage disequilibrium between Adh-3 and Adh-3t was observed. Sex differences in mouse liver and kidney ADH-A2 activities were observed, with male/female ratios of approximately 0.6 and 3 respectively for these tissue extracts.

Alcohol Dehydrogenase↗
PubMed1982

Bronchiolo-alveolar adenocarcinoma with multiple cysts.

An autopsy case of bronchiolo-alveolar adenocarcinoma in the lung is reported. The patient is a 70-year-old male who complained of severe cough with 500-600 ml watery sputum a day, loss of weight. and general fatigue. Autopsy revealed numerous whitish tumors in various sizes with multiple cysts in both lungs, with no metastasis being found in any other organs. Histological findings identified the tumor as a bronchiolo-alveolar adenocarcinoma originating from the lungs. Electron-microscopic findings showed that the tumor cells were covered by prominent microvilli, and contained abundant irregularly-shaped cytoplasmic vacuoles suggestive of mucin.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed1982

Pulmonary lesions in rats caused by intravenous injection.

Sprague-Dawley rats in a chronic toxicity test revealed specific pulmonary lesions after 180 days of intravenous injection of samples via the tail vein. Microscopically, thickening of arterial walls, periarteritis, edema of perivascular sheath, arteriosclerosis, vasodilatation, arteriofibrosis, abscess and necrosis of arterial walls, embolism and thrombus of small muscular artery or alveolar capillary, and granulomas sometimes accompanying giant cells were found in the lungs. The emboli consisted of hair of the rats, and granulomas with multinucleated giant cell formation and cellular infiltration were prominent around the emboli. The thrombi was characterized by perivascular cuffing, fibrinous and cellular components. These pulmonary lesions are thought to be caused by hair brought from the tail when intravenous injection was carried out.

Animals↗
PubMed1982

Hypophosphatasia.

An autopsy case of hypophosphatasia in lethal form in a fetus was reported. The female fetus of 40 gestational weeks was prenatally diagnosed as the specific type of congenital disease, because of no detection of calcification of whole bones by X-ray examination. Autopsy showed decrease of the anterio-posterior diameter of the chest and marked short extremities. Laboratory data revealed an extreme low value of alkaline phosphatase in the serum. Microscopical examinations showed marked retardation of calcification in the trabecule of whole bones. Family pedigree in second generations suggested that this disease was an autosomal recessive disorder and the parents were heterozygous carriers.

Abnormalities, Multiple↗
PubMed1982

A comparison of antihypertensive effects of atenolol and propranolol in the spontaneously hypertensive, DOCA/saline hypertensive and renal hypertensive rats.

Antihypertensive effects of a long-term oral regimen of atenolol were studied in SHR, DOCA/saline hypertensive and renal hypertensive rats (one kidney, one clip) in comparison with the effects of propranolol. Both the beta-blockers prevented the development of hypertension in SHR but did not affect that in DOCA/saline and renal hypertensive rats. Both of the beta-blockers produced no acute hypotensive effects on the established DOCA/saline and renal hypertension of the rat, although they produced a decrease in the heart rate.

Animals↗
PubMed1982

MuMTV antigen expression and mammary tumor incidence in non-inbred dd mice.

The expression of mammary tumor virus (MTV) antigen in the milk and various organs of three non-inbred dd mouse stocks (ddO, ddN and ddY) was examined by the immunodiffusion (ID) and micro-immunodiffusion (micro-ID) tests. The rate of MTV antigen expression in the milk was 100% at the first lactation in ddO (6/6) and ddN mice (10/10), and 23% in ddY mice (3/13). Mammary tumor incidence was 13% (mean tumor age: 12.0 months), 32% (9.6 months) and 10% (11.5 months) in ddO, ddN and ddY mice, respectively, In F1 hybrids between MTV-free BALB/c females and dd males, a high level of MTV antigen was detected by the ID test in the milk of (BALB/c X ddO) F1, however, the levels in (BALB/c X ddN) F1 and (BALB/c X ddY) F1 mice were low at the first lactation and elevated with the advance of lactation number. Mammary tumor incidence had a trend to be higher and earlier in these F1 hybrids than in non-inbred dd stocks. The development of mammary tumors and detection of MTV antigen in F1 hybrids indicate the extrachromosomal transmission of MTV by male dd mice. The micro-ID test has shown that the mammary tumors, mammary glands, male genital organs except for the testis and the salivary gland expressed MTV antigen, with a high frequency of suggesting that secondary male genital organs may play an important role in MTV infection in mice.

Animals↗
PubMed1982

Two types of hypotensive effect of beta-blocking agents.

In anesthetized and immobilized rats, an hour-long continuous intravenous injection of dl-propranolol (PR; 3 mg/kg), pindolol (PI; 1 mg/kg), oxprenolol (OX; 3 mg/kg) or atenolol (AT; 3 mg/kg) invariably resulted in moderate hypotension. When the drug-induced hypotension was plotted against the control arterial pressure (AP), two types of correlation were found. The hypotension induced by PR or PI, both known to accumulate in the brain at a high concentration was positively correlated to the control AP, whereas the hypotension produced by OX or AT, both known to penetrate the blood-brain-barrier poorly, was not. To test the hypothesis that the observed difference was attributable to the presence or lack of sympathoinhibitory action of the drug, the effect of these agents on the renal nerve activity (RNA) was examined. PR or PI diminished the tonic and reflexly evoked RNA, when the evoked RNA was elicited by sciatic nerve stimulation. No such changes were induced by OX or AT. These results demonstrate a modulatory role of sympathoinhibitory effect of beta-blocking agents in their hypotensive action.

Adrenergic beta-Antagonists↗
PubMed1982

[Effects of guanfacine on pre- and postsynaptic alpha-adrenoceptors studied in comparison with those of clonidine].

Intravenous injections of guanfacine (1 microgram-3 mg/kg) elevated dose-dependently blood pressure in adrenalectomized, pitched rats. The vasopressor activity of guanfacine was weaker than those of clonidine, an alpha 2-agonist and 1-phenylephrine, an alpha 1-agonist. However, the maximal response produced by guanfacine was the same as that produced by clonidine, while it was much smaller than that produced by 1-phenylephrine. The dose-response curve to guanfacine for increase in blood pressure was shifted in a parallel fashion to the right by 1 mg/kg of yohimbine, an alpha 2-antagonist and by 1 mg/kg of phentolamine, a nonselective alpha 1- and alpha 2-antagonist. However, 0.1 mg/kg of prazosin, a selective alpha 1-antagonist, produced an inhibition of the blood pressure rise induced by higher doses of guanfacine, but not that induced by lower doses. Guanfacine (1 microgram-1 mg/kg) inhibited dose-dependently the tachycardia induced by electrical stimulation of spinal nerves at C7-Th1 in adrenalectomized, pithed rats. The maximal inhibition by guanfacine of heart rate increase induced by electrical stimulation was about 60%. These inhibitory effects were antagonized by yohimbine and phentolamine, but not by prazosin. These results indicate that guanfacine is an alpha 2-agonist with approximately equal potency towards the pre- and postsynaptic alpha 2-adrenoceptors, just as clonidine is, but is weaker as an alpha 2-agonist than clonidine.

Adrenalectomy↗
PubMed1982

[The hypotensive effects and mechanism of SGB-483, a newly-synthesized hypotensive agent].

The effects of SGB-483, a newly-synthesized hypotensive agent, on the blood pressure were studied in unanesthetized and anesthetized rats. SGB-483 produced a significant hypotensive action in the conscious SHR and renal hypertensive (clipping) rats, and it caused reversal of the pressor response to adrenaline in the anesthetized Wistar-Imamichi rats, SHR, and clipping rats. In an isolated guinea pig aorta preparation, SGB-483 competitively inhibited the contractile response to phenylephrine with a pA2 value of 7.64 +/- 0.08. In pithed rats that were pretreated with beta-adrenoceptor blocker, the pressor effect of adrenaline (1 microgram/kg) was not completely blocked by either prazosin (1 mg/kg), an alpha 1-selective blocker, or yohimbine (1 mg/kg), an alpha 2-selective blocker. SGB-483 (1 mg/kg) had no effects on the prazosin-resistant part of the pressor effect of adrenaline, but significantly inhibited the yohimbine-resistant part. Clonidine-induced reversal of the tachycardia induced in the pithed rat by cardiac sympathetic nerve stimulation was unaffected by SGB-483, indicating that SGB-483 is a selective antagonist of the alpha 1-adrenoceptor.

Adrenergic alpha-Antagonists↗