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Biomedical subjects

J Misumi

Publications and source records attributed to J Misumi.

65 records · Page 4Linked to original sources
PubMed1976

The mechanism of low-renin hypertension: aldosterone response to sodium restriction and upright posture, angiotensin II, ACTH and potassium in patients with hypertension.

Plasma renin activity and aldosterone were measured simultaneously in 67 out-patients with essential hypertension. High aldosterone was more often in patients with high renin, and low levels of aldosterone were usual in those with low and normal renin. In order to study the mechanism by which aldosterone and renin acitvity are suppressed in low-renin hypertension, 25 patients (13 normal-renin hypertensives, 10 low-renin patients including 4 non-responders and two DOC excess hypertensives) were investigated as inpatients. Plasma renin activity, aldosterone and cortisol were determined by the following stimualtions with 3 days of sodium restriction and 2 hours of upright posture, angiotensin II infusion (at a dose which increased 20mmHg of diastolic blood pressure), ACTH administration (rapid i.m. injection of 0.25 mg of alpha 1-24 preparation) and potassium infusion (30 meq of potassium i.v.). Responses of aldosterone in normal-renin hypertensives to all stimulations were 3-5 fold increases from bases line values. Low-renin hypertensives except two of four non-responders showed the responses similar to those in normal-renin patients. The responses of two of the non-responders were similar to those in DOC excess hypertensives who showed reduced responses of aldosterone to some of these stimulations. Thus, it seems that low-renin hypertension is a clinical entity caused by a variety of mechanisms, and the mechanism by which low-renin hypertension is induced is not explained by one factor such as an unknown mineralocorticoid.

Adrenocorticotropic Hormone↗
PubMed1975

[Effects of low salt plus upright posture, angiotensin II, ACTH, and potassium upon plasma renin activity, aldosterone, and cortisol (author's transl)].

In order to study the control system of plasma aldosterone in human, we examined the effects of low salt plus upright posture, angiotensin II, ACTH and potassium upon plasma renin activity, aldosterone and cortisol in five subjects who were supposed to be normal. All of the procedures, low salt diet with below 3 g of salt and 2 hr-upright posture, 0.25 mg of Cortrosyn, angiotensin infusion to increase 20mmHG of diastolic pressure for an hour, and 30 mEq of potassium infusion stimulated plasma aldosterone significantly. Furthermore, in each subject the degrees of response to each of these stimulations were almost same. In an old woman aged 68, responses to all of stimulations were significantly lower than those in other subjects. Plasma cortisol was significantly stimulated by ACTH, but slightly reduced by potassium infusion. From these results, it is certain that plasma aldosteron levels are easily affected by a small amount of changes in angiotensin, ACTH, potassium and sodium. However, responses of aldosterone to these changes seem to be decreased in old subjects.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

Fertilization rates of small-head sperm in conventional IVF and ICSI.

Five men produced 23 ejaculates in 23 assisted reproductive technology cycles for semen analysis. In 11 of the 14 ICSI cycles and in 5 of the 9 IVF cycles, small-head sperm were found in more than 70% of the cells, having a length of < 3.5 micro m and a width of < 2 micro m. In 6 of the 14 ICSI cycles, the embryologist who performed the ICSI was not alerted to e presence of small-head sperm. Subsequent fertilization rate was significantly lower than a) the fertilization rate of the remaining 5 ICSI cycles that acted as a control, in which the embryologist was alerted to the presence of small-head sperm, and b) was lower than the 3 ICSI cycles with normal sperm head (p < .05). The 8 cell embryo and blastocyst rates in the former group were also decreased, although not significantly, compared to the latter groups. Likewise, in the 5 IVF cycles with small-head sperm, the fertilization rate was significantly lower than in the 4 IVF with normal sperm head (p < .05). Embryologists should be alerted when a high percentage of small-head sperm are detected during routine semen analysis because they may be associated with reduced fertilization and embryo outcome.

Female↗
PubMedDate not supplied

A neurophysiological study among Chinese CS2-exposed workers.

A neurophysiological study was carried out to examine peripheral neurotoxicity of extremely low levels of CS2, that is, less than 2 ppm (TWA-8hr) among Chinese viscose rayon workers. From the subjects who participated in a 1981 cross-sectional medical survey, 70 male workers exposed to CS2 and age-matched unexposed workers were randomly selected for the present neurophysiological examination. The conduction velocities of motor, sensory and slower motor fibres of the right ulnar nerve were measured using the same methods as those in the study by Seppäläinen (1974). Skin temperature was measured at the middle of the volar surface of the right forearm with a Thermistor thermometer. According to an earlier occupational hygiene survey in the plant, current personal exposures determined by a passive dosimeter method were very low; the average of daily exposure of 7 jobs studied was 1.45 ppm (range 0.2-5.0). Past and current area sampling data also suggested that occupational hygiene conditions regarding CS2 exposure in the plant had been extremely good for the previous 6 years. The present neurophysiological study clearly showed that significant reduction in the conduction velocities of motor and slower motor fibres of the ulnar nerve was detected as a consequence of chronic exposure to low levels of CS2. In the previous cross-sectional medical survey, no retinopathy was found among Chinese workers exposed to CS2 at this level. These results suggested that an effect of CS2 on the peripheral nerve would appear earlier than that on the retina.

Adult↗