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Biomedical subjects

T Tamada

Publications and source records attributed to T Tamada.

At least 217 records · Page 12Linked to original sources
PubMed1981

The effect of DL-5-hydroxytryptophan (5-HTP) on plasma prolactin in pituitary stalk sectioned rats.

5-HTP (5 mg/100 g body weight), a precursor of serotonin, was administered intravenously to pituitary stalk sectioned rats. Plasma prolactin levels were initially increased 30 and 60 min after the injection of 5-HTP and thereafter decreased. Pituitary prolactin content was decreased 60 min after the stalk section as compared to those seen following sham operation. The treatment of 5-HTP induced a moderate increase in pituitary prolactin content in the stalk sectioned rats. In order to confirm the complete disconnection of pituitary stalk after the operation, 2.5 micrograms of dopamine hydrochloride was given into the lateral ventricle of stalk sectioned rats. Plasma prolactin did not change following the administration. Our results demonstrate that 5-HTP acts either directly at the pituitary level or via some mechanism yet to be determined.

5-Hydroxytryptophan↗
PubMed1981

[Central venous catheterization using ECG monitoring and its obstetrical application (author's transl)].

We tried the central venous catheterization using the ECG monitoring lead by the catheter tip without the X-ray examination. The catheter consists of 5F sized, 70 cm, thin-walled polyethylene tube. The apex of the catheter is 60 degrees curved with heating and the exchangeable metal adaptor is attached in the proximal end. The catheter was introduced percutaneously into the cubital vein and filled with saline. The ECG lead from the catheter tip was recorded through the metal adaptor by the battery electrocardiograph. The introduction into the right atrium of the catheter was easily judged in almost all cases by the intraatrial ECG, namely, deep negative or biphasic P wave. We have tried this method in 72 cases and the success rate of insertion into the right atrium was as high as 87.5%. The right atrial pressure of the obstetrical group (19 term pregnant women) was significantly lower than that of the gynecological group (22 preoperative patients) (P less than 0.01). The pH of the right atrial blood in the obstetrical group was significantly higher than that in the gynecological group (P less than 0.01). PCO2, PO2, HCO3-, and the oxygen saturation of the obstetrical group were significantly lower than those of the gynecological group (P less than 0.01).

Adult↗
PubMed1979

Endocrinological analysis of environmental menstrual disorders.

In 139 new student nurses, a change of menstrual cycles after school entry was studied, recording their basal body temperature over more than 4 months. In some of these students, serum FSH, LH, prolactin, estradiol, and progesterone were assayed every day or every other day throughout the second cycle after entry. Forty-six out of 72 students with previously normal menstrual cycles changed the length of their cycles. In most of the cases with a change in menstrual cycle, LH seemed not to be released in adequate amounts judging by the peak of estrogen and ovulation did not occur; the lack of sufficient LH stimulation resulted in anovulatory shortened cycles, amenorrhea or prolonged ovulatory cycles, followed by delayed ovulation. Also, in these cases, corpus luteum insufficiency persisted even when the ovulation returned. Prolactin was not considered to be involved in the mechanism of environmental menstrual disorders because serum prolactin did not increase in the cases with menstrual change. It can be concluded that environmental change or stress influences LH-RH cells in the hypothalamic centers simultaneously with the stimulation of ACTH secretion, and suppresses ovulation by decreasing LH secretion, and causes the different types of menstrual disorders.

Adolescent↗
PubMed1978

Analysis of the positive feedback effect of estrogen on the release of gonadotropin in women.

In order to elucidate the positive feedback mechanism of estrogen on gonadotropin release in women, the responses of plasma LH and FSH to the constant infusion of estradiol-17 beta for a prolonged period were studied. The infusion was initiated on various days of the follicular phase and maintained for 36-66 hr at a constant rate of 500 or 1,000 microgram/24 hr. When the stimulus of estradiol was sustained for more than 30 hr in the women of the middle or late follicular phase, a positive feedback effect to elicit gonadotropin surges was observed during the maintenance of the infusion. In contrast, the stimulus of estrogen was ineffective in the early follicular phase, even if sustained for a longer period up to 66 hr. Gonadotropin levels, also, increased after the end of infusion. The magnitude of the responses, however, was much smaller, as compared to spontaneous preovulatory gonadotropin surges. In all cases, the effect of estradiol was greater for LH than for FSH. It is suggested that: 1) Preovulatory gonadotropin surges are triggered by estrogen increments rather than the withdrawal of the negative feedback effect of estrogen. 2) Low levels of estrogen for a certain period of the early follicular phase may play an important role in priming the control system which responds to the positive feedback effect of estrogen.

Estradiol↗
PubMed1977

Involvement of NAD in induced synthesis of colicin E1.

Escherichia coli K-12 nadC13 (ColE1) was starved for nicotinic acid and cellular NAD levels decreased to less than 10% of the normal. Under these conditions, induction of colicin E1 synthesis decreased to about 1% of the normal value, while 30% of the total protein synthesis remained intact. Addition of nicotinic acid reversed both the ability of the colicin induction and cellular NAD level. Induced replication of colicin E1 DNA was greatly reduced in the NAD-deprived cells.

Adenosine Triphosphate↗
PubMed1977

Requirements of glucose and incubation under static conditions for optimal colicin E1 induction.

A rapid rate and large amounts of colicin E1 synthesis were induced by incubating colicinogenic cells without aeration in the presence of glucose. The decrease in ability of colicin induction by aeration was not due to an ample supply of oxygen, but to the simple agitation of the bacterial suspension. Sugars other than glucose that support colicin synthesis were mannose, fructose, glucose-6-phosphate, and mannitol. The effect of sugars in mutants deficient in enzymes of glucose metabolism suggested that some intermediary metabolites between glucose and pyruvate are closely related to the stimulation of colicin synthesis under these conditions. Analyses of deoxyribonucleic acid replication indicated that the induced replication of the colicin E1 plasmid deoxyribonucleic acid occurred even under conditions in which colicin was not actively synthesized.

Air↗
PubMed1977

[Inhibitory effects of methyl o-(4-hydroxy-3-methoxycinnamoyl) reserpate (CD-3400) on the central nervous system (author's transl)].

Effects of methyl o-(4-hydroxy-3-methoxycinnamoyl) reserpate (CD-3400) on the central nervous system in mice, rats and cats were investigated, and a comparison was made with such effects of reserpine and rescinamine. Inhibitory effects of CD-3400 on spontaneous motor activity and conditioned avoidance response were weaker and shorter than those of reserpine and rescinnamine. In the experiments of the inhibitory effects of the central actions such as ptosis, hypothermia, decrease in motor ability, potentiation of hexobarbital and taming, reserpine was found to be the most potent followed by rescinnamine and CD-3400, respectively. High doses of CD-3400 exhibited inhibitory effects on methamphetamine-induced hyperactivity in mice and this action was weaker than those of reserpine and rescinnamine. CD-3400, 80-160 mg/kg p.o., showed no significant effects on morphine-induced analgesia, while a slight inhibition was observed on the Straub-tail reaction using morphine. Reserpine, 0.5 mg/kg i.v., resulted in a drowsy pattern in the spontaneous EEG activity and the EEG arousal response was depressed, while with CD-3400, 5 mg/kg i.v., there was no drowsy pattern. CD-3400 as well as rescinnamine and reserpine remarkably depleted 5-HT levels in brain, heart and plasma and the potency of CD-3400, particularly in the brain, was weaker than the potency of reserpine and rescinnamine. These results indicate that CD-3400 is an antihypertensive agent with a low toxicity and a weak central action.

Agonistic Behavior↗