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Biomedical subjects

S Ichikawa

Publications and source records attributed to S Ichikawa.

At least 307 records · Page 17Linked to original sources
PubMed1980

The effect of estrogen on fetal survival in progesterone-treated ovariectomized rats.

In pregnant rats ovariectomized on Day 14 of pregnancy (sperm present=Day 1), the daily injection of 4 mg progesterone maintained normal pregnancy up to Day 17, but injured fetuses bearing hematomata on their extremities appeared very frequently thereafter, in spite of successive injections of progesterone. The addition of 0.2 microgram estradiol-17 beta to the daily dose of progesterone for two successive days between Days 15 and 18 of pregnancy prevented the occurrence of fetal injuries. Estradiol-17 beta was found to be more effective in preventing fetal damage than estrone or estriol. The results suggest that while progesterone is essential for the maintenance of pregnancy, estrogen is also necessary at the time when the conceptus elongates and becomes cylindrical.

Animals↗
PubMed1980

Effect of the placenta on the growth and function of artificially formed secondary corpora lutea of pregnancy in rats.

PMSG-induced prepubertal pregnant rats were injected with hCG on Day 7 of pregnancy to induce the formation of secondary corpora lutea (CL) in addition to the primary CL of pregnancy. The rats bearing two sets of CL were hypophysectomized on Day 11 of pregnancy (Day 3 of the secondary CL age) and their primary CL were removed on Day 13 of pregnancy (Day 5 of the secondary CL age). The operations did not affect the fetal growth until Day 18 of pregnancy when the weight of and progesterone secretion of the secondary CL rapidly increased. Hysterectomy on Day 18 of pregnancy (Day 10 of the secondary CL age), however, induced regression of CL and rapidly decreased the progesterone secretion. These results suggest that placentas between Days 15 and 18 of pregnancy could maintain the function of CL at Days 7-10 of CL age when LH is indispensable as a luteotropic hormone, and that placentas between Days 18 and 21 of pregnancy could support the rapid growth of CL at Days 10-13 of CL age. Placental hormones which would participate in these luteotropic events have been discussed.

Animals↗
PubMed1980

The effect of oestrogen on uterine plasticity in late pregnant rats.

Intrauterine pressure was recorded in anaesthetized rats on Day 20 of pregnancy by the replacement of a conceptus with a balloon. Intrauterine pressure in ovariectomized pregnant rats treated with progesterone alone was markedly higher than that in intact pregnant rats, but treatment with oestradiol as well reduced values to those of controls. Oestriol and oestrone were less effective. Uterine tolerance, tested by increasing the balloon volume until the uterus ruptured, was greater than 6.5 ml in intact rats and in ovariectomized rats treated with progesterone + oestradiol, but rupture occurred at a volume of 4.3 ml when progesterone alone was used. One of the roles of oestrogen during late pregnancy in rats may be to ensure sufficient plasticity of the uterus to allow for the increase in conceptus size.

Animals↗
PubMed1978

Pressor responses to norepinephrine in rabbits with 3-day and 30-day renal artery stenosis. The role of angiotensin II.

Pressor responses to norepinephrine (NE) infusions were examined in normal rabbits, in rabbits with renal artery stenosis of over 30 days' duration (chronic renal hypertensive rabbits), and in rabbits with renal artery stenosis of 3 days' duration (3-day clipped rabbits). The 3-day clipped rabbits did not have hypertension, but they showed the same increased pressor responses to NE as did the chronic renal hypertensive rabbits, which was about 2.5 times that of the normal rabbits. Plasma renin activity (PRA) was the same in the 3-day clipped rabbits as in the normal group, but in the chronic renal hypertensive rabbits the PRA was significantly below normal. Infusions of angiotensin II (A II) in either subpressor or pressor amounts potentiated the pressor responses to NE in normal rabbits, whereas, in 3-day clipped rabbits and chronic renal hypertensive rabbits, A II in subpressor or pressor doses did not alter the pressor responses to NE. Infusion of the A II antagonist, [1-sarcosine, 8-isoleucine]angiotensin II, did not alter the pressor responses of normal rabbits to NE, but this A II analogue completely abolished the pressor hyperresponsiveness to NE in the 3-day clipped rabbits and greatly reduced the NE hyperresponsiveness in the chronic renal hypertensive rabbits; this A II antagonist did not alter the control arterial pressure in any of the three groups of rabbits. These studies show that the increased pressor response to NE in rabbits with renal artery stenosis occurs before the onset of hypertension and thus is not merely a result of the hypertension. Also, these results provide evidence that A II plays an important role in the increased pressor responses to NE in hypertensive and prehypertensive rabbits.

Angiotensin II↗
PubMed1977

The diurnal rhythm of plasma aldosterone and plasma renin activity in patients with congestive heart failure.

Study on a diurnal rhythm of plasma aldosterone (PA) and plasma renin activity (PRA) was performed in 8 patients with congestive heart failure. All patients had been digitalized and received diuretics under mild sodium restriction. An obvious diurnal rhythm of PA similar to the normal subjects, with the lowest value in the evening and the highest value in the morning, was observed in 7 of 8 cases, while a diurnal rhythm of PRA was obscure except in one case. The PA generally did not run parallel with PRA. Although the reason of the absence of PRA diurnal rhythm in congestive heart failure was not clear, it was considered that reninangiotensin system did not play a significant role for the development of PA diurnal rhythm in congestive heart failure. The determined PA values were entirely within normal range except in 2 cases, although they were administered the potent diuretics chronically. A high PA value was observed only in early morning in one case, while all determined PA values were extremely high in another case with severe congestive heart failure involved in cardiac liver cirrhosis. The PRA values were relatively low in 2 cases, normal in 5 and high in one.

Adult↗
PubMed1977

[The general pharmacological actions of KW-1062, a new aminoglycoside antibiotic (author's transl)].

The general pharmacological actions of KW-1062 were investigated in order to estimate the effects on the host animals. KW-1062 showed little or no effect on the central nervous system, cardiovascular system, smooth muscle, skeletal muscle, hemolysis, blood coagulation, dermal tissue permeability and antigenicity tests at high doses. KW-1062 showed urinative effect and ototoxicity. But ototoxicity of KW-1062 was less potent than that of gentamicin. KW-1062 has been proved to have a safety margin wider than that of other aminoglycoside antibiotics.

Aminoglycosides↗