Search PubMed⌕ Search

Biomedical subjects

T Otsuki

Publications and source records attributed to T Otsuki.

At least 109 records · Page 6Linked to original sources
PubMed1995

[A study on the effect of cortisol and progesterone on cytosolic arachidonic and palmitic acid concentrations in cultured human myometrial cells].

Glucocorticoids inhibit prostaglandin synthesis in several cell types, presumably by inhibiting arachidonic acid deacylation from phospholipids. We studied the effects of cortisol (F) and progesterone (P) on fatty acid release from cultured human myometrial cells. Confluent monolayer cultures of myometrial cells were adapted to steroids containing medium for 24 hours and the intracellular arachidonic acid and palmitic acid concentrations were determined. In the presence of fetal calf serum (FCS), the palmitic acid concentrations significantly decreased after the addition of 10(-7)M F. In the absence of FCS, the concentrations of both fatty acids were markedly increased after the addition of F. During oxytocin stimulation, the arachidonic acid concentration did not change but the palmitic acid concentration decreased slightly after the addition of F. A similar evaluation was done with P. The palmitic acid concentration decreased slightly after the addition of 10(-5)M P in the presence of FCS but increased markedly in the absence of FCS. During stimulation with oxytocin, the fatty concentrations of fatty acids decreased significantly in a dose-dependent manner. These results suggest that both F and P are implicated as regulatory factors in the activation of arachidonic acid cascade.

Arachidonic Acid↗
PubMed1995

[The mechanism of beta-receptor desensitization in human myometrial culture cell].

Beta-adrenoceptor desensitization is considered to be primarily due to phosphorylation of receptors by protein kinase A (PKA) and beta-adrenaline receptor kinase (beta-ARK) and sequestration of receptors themselves. But in the human uterine muscle, the desensitization mechanism has been evaluated only as a phenomenon, and there are few studies on its mechanism. We evaluated cAMP production by beta-agonist and changes in the number of beta-receptors in cultured human myometrial cells. Uterine muscle cell were obtained from patients with benign disease before menopause and cultured. 1) At the confluent stage, dl-Isoproterenol Hydrochloride (ISP) was added under various conditions, and the intracellular cAMP concentration was determined by EIA. 2) After the addition of ISP (10(-6) M), plates were incubated at 37 degrees C, and beta-AR on the cell membrane surface (S beta-AR) and total beta-AR (T beta-AR) was measured in a binding assay with 125I-pindolol. The production of cAMP dose-dependently increased 30 minutes after the addition of ISP at 10(-6) M or higher, but rapidly decreased thereafter. T beta-AR was similar in the cells treated with ISP (10(-6) M) and the untreated cells. On the other hand, S beta-AR decreased by about 50% in the ISP treated cells. These result suggest the desensitization of beta-AR in human uterine muscle, and the involvement of the sequestration mechanism as its cause.

Cells, Cultured↗
PubMed1994

Mutations in the coding region of c-MYC in AIDS-associated and other aggressive lymphomas.

Our previous studies of the translocated MYC gene in Burkitt's lymphoma showed the existence of clustered somatic mutations located in the transcriptional activation domain. We now report that aggressive lymphomas arising in the acquired immunodeficiency syndrome (AIDS) contain similar mutations and that the presence of mutations is correlated with the rearrangement of the oncogene. Mutations were also found in other de novo non-AIDS, non-Burkitt's aggressive lymphomas with MYC rearrangements. An unusual asparagine to serine mutation at codon 11 was identified in several transformed follicular lymphomas without MYC rearrangement but not in normal tissues from patients with this mutation. These findings indicate that AIDS-associated and other de novo aggressive lymphomas with the MYC gene rearrangement are subject to the same mutation and selection process that affects Burkitt's lymphomas.

Amino Acid Sequence↗
PubMed1994

Stereotactic endoscopic resection of angiographically occult vascular malformations.

Total resection of angiographically occult vascular malformations was performed in four patients using stereotactic open-system endoscopy. The lesions were relatively small but localized deep in the brain or involving eloquent cortex. Fiber-guided YAG laser coagulation was efficient for haemostasis and no significant complication was seen in any case. Endoscopic stereotactic laser surgery by open-system endoscopy is considered a safe and promising treatment for small AOVM's located in deep or eloquent neural structures.

Adult↗
PubMed1994

Endoscopic resection of a subthalamic cavernous angioma: technical case report.

Endoscopic resection of a cavernous angioma at the subthalamic region was performed in a 33-year-old woman who presented with diplopia and progressive hemiparesis caused by recurrent hemorrhages. The entire surgical procedure was done through an 8-mm guiding tube inserted stereotactically from a frontal burr hole via an approach that traversed the anterior limb of the internal capsule. The patient's symptoms improved after surgery. This is believed to be the first report describing successful resection of a cavernous angioma located at the subthalamic region.

Adult↗
PubMed1994

Stereotactic gamma-thalamotomy with a computerized brain atlas: technical case report.

Radiosurgical stereotactic thalamotomy was performed in a patient with parkinsonian tremor with a computerized stereotactic brain atlas, which was transformed to fit the patient's thin-sliced magnetic resonance image to select an optimal target in the nucleus ventralis intermedius of the thalamus. The patient's tremor and rigidity disappeared and have not appeared again for more than 1 year since the eighth postoperative month. A method for converting the presurgically planned stereotactic coordinates in the atlas coordinate system to the coordinates in the frame coordinate system is described.

Aged↗
PubMed1994

[Lipoprotein Z].

The term lipoprotein Z (remnant-like particles) refers to lipoproteins that do not have an immunoaffinity to gel mixture of anti-apo A-I and apo B100 monoclonal antibodies (JI-H antibody). Lp Z is enriched in apo E and cholesterol esters. Quantification of this lipoprotein provides a useful index of atherogenic chyromicron and VLDL remnant particles. Serum concentration of this lipoprotein is well correlated to serum triglycerides in normal subjects and patients with hypertriglyceridemia, and to serum LDL-cholesterol in normal subjects. The normal range of this lipoprotein is below 5 mg/dl and the increased serum concentration is often observed in ischemic heart disease, diabetes mellitus, hypertriglyceridemia and fatty liver.

Diabetes Mellitus↗
PubMed1993

Alterations in beta-adrenergic receptor density and cyclic-AMP level in the myocardium of rats chronically treated with alcohol.

An impaired function of the myocardial beta-adrenergic receptor system has been reported in patients with end-stage heart failure and this impairment has been postulated to be a factor in further deterioration of cardiac contractile function. As ventricular dysfunction is often associated with prolonged alcohol abuse, we investigated whether or not chronic administration of ethanol could induce alterations in the beta-adrenergic receptor adenylate-cyclase system in rats. Male Wistar rats of 8 weeks of age received 33% ethanol in drinking water for 3 months. As compared with control rats drinking water, the ethanol-treated rats showed weight loss and an increase in the heart/body weight ratio. Chronic ethanol increased myocardial contents of norepinephrine and epinephrine, possibly resulting from sympathoadrenal activation. The beta-adrenergic receptor density (Bmax) of the myocardial membrane was significantly decreased in the ethanol-treated rats (27.7 +/- 9.9 vs 39.0 +/- 6.0 fmol/mg protein, p < 0.01), while the affinity (Kd) did not differ between the two groups. The myocardial content of cyclic-AMP was also reduced in the ethanol rats (865 +/- 59 vs 1055 +/- 83 pmol/g w.w., p < 0.01). These observations indicate that chronic ethanol administration depresses the function of the beta-adrenergic receptor adenylate-cyclase system. The decreased beta-adrenergic receptor density was partly attributed to down-regulation due to increased sympathetic stimulation. This impaired function may contribute to the cardiac contractile dysfunction observed in chronic alcoholics.

Animals↗
PubMed1993

[The effect of oxytocin stimulation on PGE2, 6keto PGF1 alpha production in human myometrial monolayer culture].

In order to clarify the mechanism by which oxytocin induces the generation of prostaglandin (PG) in human myometrial smooth muscle cell, we determined the concentration of PGE2 and 6ketoPGF1 alpha in the culture supernatant of human myometrial monolayer cells stimulated by oxytocin. PGE2 and 6ketoPGF1 alpha demonstrated a biphasic increasing curve when oxytocin was added. The first increase, phase 1, was a transient phenomenon with a peak at 20 seconds whereas the second increase, phase 2, was a continuous phenomenon starting at 120 seconds. Moreover, phase 1 was significantly inhibited by the DG lipase inhibitor, RHC80267. Phase 2 was significantly inhibited by the PLA2 inhibitor, Mepacrine. Phase 1 and 2 were dose dependent in the range 10(-10) to 10(-6) M. PG production at rest during which 6ketoPGF1 alpha was higher than PGE2, was reversed by oxytocin stimulation. These results suggest that oxytocin stimulation would actuate biphasic PG production, and this mechanism would probably regulate the myometrial construction in labor-pain initiation.

Calcium↗
PubMed1993

[The effect of oxytocin on production of free fatty acid in primary human uterine myometrial cell culture].

Oxytocin(OT) is considered to have several activities besides strongly inducing myometrial contraction by activating phosphatidilinositol-specific phospholipase C(PI-PLC). These include reconstructing the phospholipid constituents of the cell membrane and activating a variety of fatty acid producing systems. On the other hand, pregnancy-related steroid hormones which are produced by the fetus, placenta and mother are considered to be closely involved in the maintenance of pregnancy and the initiation of labor. In the present study with cultured myometrial cells, we examined what effect these steroid hormones might exert on the intramyometrial production of fatty acid by OT. Our results confirmed bi-phasic production of arachidonic acid(AA), linoleic acid(LA), palmitic acid(PA), and stearic acid(SA) by OT. Phase 1 was an increasing but transient phenomenon having its peak at 30 sec. It is considered to be derived from phosphatidylinositol bis-phosphate. Phase 2 was a persistent and increasing phenomenon which was initiated after 120 sec. It is considered to be mediated by Ca-dependent phospholipase. We also studied the effect of steroid hormones on the production of fatty acid. For AA, LA, and PA, we confirmed that dehydroepiandrosterone sulfate(DHAS) shortened the time taken in reaching the peak of Phase 1 to half of that of the control, and progesterone(P) extended the time 2-3 fold. These findings suggest that DHAS, P and F might modify the human myometrial construction mechanism as a factor which regulates the quantity and velocity of fatty acid production.

Arachidonic Acid↗
PubMed1993

[Effects of steroid hormones on change in [Ca2+]i following oxytocin stimulation in cultured human myometrial cells, and on myometrial oxytocin receptor].

It is considered that steroid hormones, the concentrations of which vary during pregnancy, play an important role in the initiation of delivery. In the present study, we measured intracellular Ca2+ ([Ca2+]i) change following oxytocin stimulation in cultured human myometrial cells with fura-2, a fluorescent Ca2+ indicator. We also studied the effect of the steroid hormones on changes in [Ca2+]i due to oxytocin stimulation. When the [Ca2+]i change due to 10(-6) M oxytocin reached 100%, the addition of 10(-6) M DHAS (dehydroepiandrosterone sulfate) just before the stimulation raised the [Ca2+]i level to 207%, whereas that of 10(-6) M progesterone dropped to 64%. Moreover DHAS accelerated the speed of increase until the maximum response of [Ca2+]i, while progesterone decelerated it. In another study, human myometrial plasma membrane was solubilized in 7.5mM CHAPSO solution and applied to a binding study. Oxytocin receptors of two different molecular weights, namely 350kD(OTR-1) and 39kD(OTR-2), were extracted from solubilized plasma membrane by employing a gel filtration column. Binding assays were performed for OTR-1 and OTR-2 in the presence of DHAS and progesterone (10(-5) M). The results showed that DHAS enhanced the binding affinity of the receptors, whereas progesterone reduced the maximum binding capacity. It is therefore considered that the steroid hormones added just before oxytocin stimulation might act on receptor levels and modify intracellular Ca2+ response over short periods.

Calcium↗
PubMed1993

[The effect of steroid hormone on oxytocin receptor expression in primary human uterine myometrial cell culture].

In the present study, we have examined the steroid hormone effect on oxytocin receptor (OTR) expression in human myometrial monolayer culture. The myometrial cells were cultured for 24-72 hours in serum-free media with various concentrations of steroid hormones. The plasma membrane of the cultured cells was then collected. The 125I-oxytocin(OT) was employed for a binding assay and the mean binding and dissociation constant were evaluated by Scatchard analysis. 1. The OT binding values in the presence of estradiol free, 10(-8) M, and 10(-7) M at 72 hours were 19.85, 28.12, and 36.20pM/mg protein, respectively. 2. The OT binding values in the presence of estradiol (10(-7) M) at 24, 48, and 72 hours were 17.85, 23.72, and 36.20pM/mg protein, respectively. 3. Dehydroepiandrosterone sulfate (10(-5) M) exerted almost no effect on the OTR expression by estradiol (10(-7) M). Cortisol (10(-5) M) decreased the amount of OTR expressed by estradiol. 4. The changes in OTR expression caused by estradiol (10(-7) M) were inhibited according to the concentration by progesterone. The concentration of progesterone at which OT binding was reduced 50% was 2.7 x 10(-6) M (E/P ratio = 0.037). These results suggested that estradiol increased the amount of OTR discovered in human myometrial cells in a time and concentration dependent manner, while progesterone inhibited the changes in OTR expression by estradiol in a concentration dependent manner. Thus, it was indicated that the changes in the E/P ratio during pregnancy which regulate the OTR expression control the myometrial contraction.

Cell Membrane↗
PubMed1990

Monosodium urate test: a new analgesic test by crystal-induced monoarthritis in rats.

The analgesic effects of various agents were evaluated in knee joint monoarthritic rats where arthritis was induced by monosodium urate (MSU) crystals injected into the knee joint cavities. The weight supported by each hind limb was measured quantitatively using pressure transducers, which revealed dose-dependent recovery produced by various analgesics including morphine but no changes in value by sedatives such as chlorpromazine. Relative potency obtained from the value of ED50 of each analgesic agent was congruent with that in clinical use. The MSU test may be quite suitable for quantitative and objective evaluation of the analgesic effects of various agents, particularly for spontaneous and tonic pain.

Analgesia↗