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Biomedical subjects

K Kotani

Publications and source records attributed to K Kotani.

At least 109 records · Page 6Linked to original sources
PubMed1990

Inhibitory mechanism of cis-polyunsaturated fatty acids on platelet aggregation: the relation with their effects on Ca2+ mobilization, cyclic AMP levels and membrane fluidity.

The in vitro inhibitory effects of cis-polyunsaturated fatty acids, linolenic (18:2 delta 9,12), alpha-linoleic (18:3 delta 9,12,15) and eicosatrienoic (20:3 delta 11,14,17) acid, on bovine platelet aggregation and their inhibitory mechanism were investigated. These fatty acids inhibited platelet aggregation induced by ADP and thrombin to similar extent. Fluorescence analyses with fura-2-loaded platelets showed that, in the concentration ranges that inhibited aggregation, they also inhibited agonist-induced increase in cytoplasmic Ca2+. According to radioimmunoassay study, addition of these fatty acids increased cyclic AMP contents in the presence of theophylline corresponded with their inhibitory effects on aggregation. These fatty acids induced a 1.6-1.8-fold increase over basal concentration of cyclic AMP in the concentration ranges that fully inhibited aggregation. On the other hand, saturated fatty acid, stearic acid, affected neither aggregation nor cyclic AMP levels. As reported previously [1985) Biochim. Biophys. Acta 818, 391), these unsaturated fatty acids induced increase in membrane fluidity in the same concentration range. These results suggest that inhibition of platelet aggregation by cis-polyunsaturated fatty acids is due to the increase in cyclic AMP levels. This increase seems to be due to stimulation of adenylate cyclase which is mediated by membrane perturbation.

8,11,14-Eicosatrienoic Acid↗
PubMed1990

[Fundamental experiment of expansile force of expandable metallic stent].

So far expansile force of expandable metallic stent has been estimated by only wall-distending pressure P. We estimated expansile force of stent by not only P but also a force per one unit length of wire F. F corresponds to the degree of digging into the vessel wall. P and F were thought to be useful in selecting the best stent.

Elasticity↗
PubMed1990

Simple estimation of ideal body weight from body mass index with the lowest morbidity.

Body mass index (BMI) is expressed by the body weight (kg) divided by height (m) squared. Therefore, if we know ideal BMI, ideal body weight (kg) of each individual can be calculated by a formula: Ideal BMI x height (m)2. In order to estimate ideal BMI, we investigated average BMI with the lowest morbidity using 4565 Japanese men and women aged 30 to 59 years. Their BMI distributed widely with the highest frequency at 23 in men and 21 in women. The morbidity was evaluated by the number of medical problems that the subjects with each BMI have. The BMI associated with the lowest morbidity was calculated to be 22.2 kg/m2 in men and 21.9 kg/m2 in women according to the quadratic regression curves derived from the relation between BMI and morbidity. From these data, we propose that an ideal body weight in Japanese is 22 x height (m)2.

Adult↗
PubMed1990

Close correlation of intra-abdominal fat accumulation to hypertension in obese women.

The relation between intra-abdominal visceral fat accumulation and blood pressure was investigated in 67 obese women (mean body mass index, 33.6 +/- 3.1; average age, 50 +/- 11 years). As an index of intra-abdominal fat accumulation, the ratio of the intra-abdominal visceral fat area to subcutaneous fat area was determined using a computed tomographic section at the level of the umbilicus. When the obese subjects were divided into a hypertensive group and a normotensive group, the ratio of the intra-abdominal visceral fat area to subcutaneous fat area in the hypertensive group was significantly higher (0.53 +/- 0.33 versus 0.29 +/- 0.12, p less than 0.01). Significant correlations between the ratio of intra-abdominal visceral fat area to subcutaneous fat area and systolic blood pressure (r = 0.62, p less than 0.001) and diastolic blood pressure (r = 0.53, p less than 0.001) also were found. However, no significant difference existed in either the body mass index or the waist-to-hip circumference ratio between the hypertensive and normotensive groups. Plasma renin activity, aldosterone, epinephrine, and norepinephrine levels were not significantly different between the two groups. Moreover, the correlation between the ratio of the intra-abdominal visceral fat area to subcutaneous fat area ratio and blood pressure was found independent of age and body mass index by multiple regression analyses. We conclude that intra-abdominal fat accumulation itself may play an important role in the pathogenesis of hypertension in obesity.

Abdomen↗
PubMed1990

[Physical properties of expandable metallic stents; including the procedure of stent production].

Nowadays expansile force of self-expandable metallic stent is estimated by only wall-distending pressure P. We estimated the expansile force of the stent by not only P but also F. F expressed the degree of digging into the vessel wall and was defined as a force per one unit length of wire. P and F were thought to be useful in selecting the best stent. We also introduced the procedure of stent production.

Biomechanical Phenomena↗
PubMed1987

Inhibitory effects of long-chain alkyltrimethylammonium ions on aggregation of bovine platelets and the relation of their effects to Ca2+ mobilization.

The inhibitory effects of alkyltrimethylammonium ions on ADP- and thrombin-induced aggregation of bovine platelets were investigated. The ammonium cations inhibited the two aggregation reactions to similar extents. The relationship between their inhibitory effects on ADP-induced aggregation and their alkyl chain lengths from C8 to C18 was investigated. Results showed that the inhibitory effects of ammonium cations increased with increase of their alkyl chain lengths up to C16, and that the increase was linear with chain lengths of up to C14. This linear relation and slope of the linear regression line suggested that the inhibitory effects of the ammonium cations depended on their partitioning into the membrane. However, unlike long-chain unsaturated fatty acids, they did not affect the membrane fluidity of the platelets. Fluorescence analysis of fura-2 loaded platelets revealed that, in the concentration range where the alkyltrimethylammonium ions inhibited aggregation, they inhibited agonist-induced increase in cytosolic Ca2+ both in the presence and absence of extracellular Ca2+. These results suggest that inhibition of platelet aggregation by alkyltrimethylammonium ions is mainly due to their inhibition of increase in cytoplasmic Ca2+ by inhibition of both intracellular Ca2+ mobilization and Ca2+ uptake.

Adenosine Diphosphate↗
PubMed1987

Distribution of alpha-(gamma-aminobutyryl)-hypusine.

The distribution of alpha-(gamma-aminobutyryl)-hypusine was examined in several organs of the rabbit and in the brain of the rat, rabbit, dog, ox, and monkey. The peptide occurred only in the brains, but appeared to be absent from dog brain. Concentrations were higher in the cerebral hemispheres than in other portions of the brain. No significant difference between white and gray matter was observed.

Animals↗
PubMed1986

Isolation and identification of alpha-(gamma-aminobutyryl)-hypusine.

A new dipeptide, alpha-(gamma-aminobutyryl)-hypusine, was identified in bovine brain. This compound was isolated from trichloroacetic acid-soluble fraction of bovine brain with five steps of ion-exchange chromatography. Its structure was postulated by routine chemical analyses and determined by synthesis. The amount of the compound isolated from 1.2 kg of bovine brain was 870 nmol.

Animals↗
PubMed1983

[Acoustical analysis of joint-sound through passive motion--with special reference to degenerative osteoarthrosis of the knee joints].

Sounds from the joints are still in the mysterious zone. It seems to be important to study the sound which occurs on motions. Here, a new analysing method and its clinical application are presented and discussed. The joint which is studied, is moved in some ranges for four seconds in the unechoic chamber, and a special microphone is kept to touch on the pan-articular skin manually throughout the motion. These collected sounds are analyzed with a narrow band spectrum analyzer (Br uel & Kjaer Co., 2031 Type) and a computer. In the unechoic chamber, it may diminished the background noises. The narrow band spectrum analyzer made it possible not to use the magnetic tape which usually induced much noise. Furthermore, as the computer system is utilized, it become easy to compile the data of each frequency analysis and to obtain over all value, with which the sound volume can be compared with each other. The over all value means an integrated volume of each joint sound. In this paper, joint sound were obtained from normal and pathological human joints. In the normal cases, the frequency analysis data showed almost flat spectrum curves, and the total over all values (0.5 kHz to 5 kHz) were usually less than 80 dB. On the other hand, in the pathological joints which had bony changes affected by rheumatoid arthritis, degenerative osteoarthritis, fracture, and others, the frequency analysis showed elevated curves in range from 0.5 kHz to 4.0 kHz, and the total over all value increased in each pathological joint. In 85 cases of osteoarthrosis of the knee joints, the total over all values were a wide dispersion from 76 to 104 dB. And these values and radiological grading (by Swanson) correlated to each other. The over all values at each 0.5 kHz interval, especially from 0.5 to 1.5 kHz, were maximum ones in each radiological gradings. It is concluded that these results in osteoarthrosis cases, are related to with radiological gradings.

Acoustics↗
PubMed1982

The hand and environment (3)--physiological changes of digital functions in two age groups studied by vibratory stimulations and a cold water immersion.

Skin temperature, vibratory sensibility and pinch strength of the hand were recorded continuously in 20 healthy adults through two vibratory stress tests (32 Hz and 125 Hz) and a cold water (10 degrees C) immersion (for 10 min) test in a climatic chamber (20 degrees C, 50% humidity). As a stressor to the hand, the immersion was the most effective and the vibrator stress at 32 Hz was next. As a detector for function of the hand, vibratory sensibility at 125 Hz was proved to be the most valuable and the digital temperature was the next. As to aging, the mature age group showed low vibratory sensibilities at 63 Hz, higher digital temperatures, stronger pinch strengths, and quicker recoveries after the stress tests. Along the passage of time after entering the chamber, the vibratory sensibilities and the pinch strengths did not show any changes. However, the digital temperatures became continuously lower.

Adult↗
PubMed1978

Changes of serum anti-thyroid antibodies during and after pregnancy in autoimmune thyroid diseases.

Changes of serum anti-thyroglobulin haemagglutination antibodies (TGHA) and anti-thyroid microsomal haemagglutination antibodies (MCHA) were observed during pregnancy and after delivery in Graves' disease and autoimmune thyroiditis. Both TGHA and MCHA decreased as pregnancy progressed, and sometimes they became negative in late pregnancy. Transient increases of TGHA and MCHA were observed after delivery and the antibody titres reached peaks about 3-4 months post-partum in more than halft the patients. In some patients, antibodies developed after delivery. Similar transient increases of antibodies were observed after spontaneous and therapeutic abortion. These changes seem to be induced by physiological and immunological changes occurring during pregnancy and after delivery.

Abortion, Spontaneous↗