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Biomedical subjects

A Imai

Publications and source records attributed to A Imai.

At least 19 recordsLinked to original sources
PubMed2006

Gi protein-mediated translocation of serine/threonine phosphatase to the plasma membrane and apoptosis of ovarian cancer cell in response to gonadotropin-releasing hormone antagonist cetrorelix.

Serine/threonine protein phosphatase 2A (PP2A), a crucial enzyme in apoptosis control, has been demonstrated within the plasma membrane as well as in the soluble fraction. This study aimed to examine hormonal translocation of PP2A to the plasma membrane in gonadotropin-releasing hormone (GnRH)-responsive ovarian cancer cells. Apoptosis of ovarian cancer cell lines Caov-3 and SK-Ov-3 was quantified by nuclear morphology after staining with Hoechst 33342 dye. PP2A protein and activity in plasma membrane were assessed by immunohistochemical staining with PP2A-specific antibodies and by the measurement of the dephosphorylation of phosphopeptide highly selective for the PP2A, respectively. Incubation for 48 h with a GnRH antagonist cetrorelix caused parallel increases in the percentage of cells undergoing apoptosis and the membrane-associated PP2A activity; half-maximal effects occurred with 5 nmol/l cetrorelix. PP2A protein was also localised to the plasma membrane when the cell lines were exposed to cetrorelix. Pretreatment of the cells with pertussis toxin, but not cholera toxin, completely inhibited cetrorelix-stimulated apoptotic cell death and PP2A redistribution. These findings demonstrate that translocation of PP2A to plasma membrane is closely coupled to the onset of apoptosis in ovarian cancer cells exposed to GnRH antagonist. These GnRH-induced cellular events may be mediated through pertussis toxin-sensitive Gi protein-linked GnRH receptor.

Apoptosis↗
PubMed2006

Runoff and loads of nutrients and heavy metals from an urbanized area.

To investigate the run-off characteristics of dissolved and particulate substances from a heavily urbanized area (basin area: 95 ha, percentage of impervious surfaces: 60%), sensors for measuring water level, water temperature, DO, pH, electric conductivity (EC), turbidity and ammonium ion were placed in the channel connecting storm sewers and natural river, together with water sampling for analyzing SS, nutrients and metals. While both turbidity and EC showed apparent "first flush", the peaks of EC were always earlier than those of turbidity. In a similar manner, dissolved nutrients and metals exhibited earlier "first flush" compared with particulate nutrients and acid-extractable metals. Significantly positive correlations between EC and dissolved substances as well as those between turbidity and particulate (acid-extractable minus dissolved) substances were usually observed, and two distinct different regressions were found between the two datasets separated before and after the concentration peaks. Using these relationships, the total loads during the respective rainfall events were calculated on the basis of EC and turbidity changes. The total loads of nitrogen, zinc, etc. were nearly proportional to the lengths of non-rainfall periods before the events, indicating that these loads derived from the atmospheric deposition.

Cities↗
PubMed2005

A new airway device for small laboratory animals.

There is a need for a device for improved management of the airway of small laboratory animals during general anaesthesia. This report introduces such a device, referred to here as the airway device (AD). The AD has some similarity to the laryngeal mask airway (LMA) developed for human patients, but the mask portion of the device is specifically designed for small laboratory animals. In addition, the device has an oesophageal extension and unlike the LMA does not have a cuff associated with the mask. This report also shares experience of tests of one prototype AD with six New Zealand white rabbits. The AD was used for administering isoflurane and its effectiveness was evaluated during conditions of spontaneous and controlled intermittent positive pressure ventilation. The results provide encouragement for further development of the AD for airway management of small laboratory animals.

Anesthesia, General↗
PubMed2004

Animal dependence of inhaled anaesthetic requirements in cats.

BACKGROUND: The minimum alveolar concentration (MAC) of an inhaled anaesthetic describes its potency as a general anaesthetic. Individuals vary in their sensitivity to anaesthetics and we sought to determine whether an individual animal's sensitivity to inhaled anaesthetics would be maintained across different agents. METHODS: Six female mongrel cats, age 2 yr (range 1.8-2.3) and mean weight 3.5 (SD 0.3) kg, were studied on three separate occasions over a 12-month period to determine the MAC of isoflurane, sevoflurane and desflurane. Induction of anaesthesia in a chamber was followed by orotracheal intubation and maintenance of anaesthesia with the inhaled agent in oxygen delivered via a non-rebreathing circuit. MAC was determined in triplicate using standard tail-clamp technique. RESULTS: Mean MAC values for isoflurane, sevoflurane and desflurane were 1.90 (SD 0.18), 3.41 (0.65) and 10.27 (1.06)%, respectively. Body temperature, systolic pressure and Sp(O(2)) recorded at the time of MAC determinations for isoflurane, sevoflurane and desflurane were 38.3 (0.3), 38.6 (0.1) and 38.3 (0.3) degrees C; 71.2 (8.3), 74.6 (15.9) and 88.0 (12.0) mmHg; 99.2 (1.1), 99.1 (1.3) and 99.4 (0.8)%, respectively. Both the anaesthetic agent and the individual cat had significant effects on MAC. Correlation coefficients for comparisons between desflurane and isoflurane, desflurane and sevoflurane, and sevoflurane and isoflurane were 0.90, 0.89 and 0.97, respectively. CONCLUSIONS: These findings show that an individual has a consistent degree of sensitivity to a variety of inhaled anaesthetics, suggesting a genetic basis for sensitivity to inhaled anaesthetic effects.

Anesthetics, Inhalation↗
PubMed2003

Treatment of perimenopausal women with uterine myoma: successful use of a depot GnRH agonist leading to a natural menopause.

Gonadotrophin-releasing hormone agonists (GnRHa) reduce the size of uterine fibroids and relieve patients of myoma-related symptoms. However, rapid regrowth frequently occurs after the therapy is stopped. We attempted to determine whether GnRHa therapy could lead perimenopausal women carrying symptomatic myomas to the natural onset of the menopause. A retrospective analysis of 145 patients who received GnRHa for 24 weeks demonstrated that after cessation of therapy no menstruation occurred over 25 weeks in women aged over 45 years, with elevated levels of follicle-stimulating hormone (FSH) and luteinising hormone (LH) > 25 mIU/ml. To extend this study, we studied prospectively 21 women, aged 45 years and older who had regular menstruation with symptoms attributed to myomas and elevated days 3 - 5 FSH and days 3 - 5 LH levels ( > 25 mIU/ml). After discontinuation of GnRHa (leuprorelin acetate, 1.88 mg) therapy for 6 months, menstruation occurred in only two of 21 individuals but the remaining 19 cases had no menstrual bleeding. It is suggested from this study that the rise in early follicular phase serum gonadotrophins, in particular FSH > 25 mIU/ml, may precede the natural menopause following (or during) GnRHa therapy in older women. Measuring days 3 - 5 serum FSH concentrations may make it easier to decide on the optimal duration of therapy for symptomatic uterine fibroids in perimenopausal women aged > 45 years.

Adult↗
PubMed2003

Magnetic resonance imaging in the evaluating of double uterus and associated urinary tract anomalies: a report of five cases.

Uterine anomalies are associated with unilateral renal aplasia. We present the MR features of five cases with 'double' uteri. The anomalies consisted of four cases of uterus didelphys and one of a complete septate uterus. All the cases with uterus didelphys also had a longitudinal vaginal septum. The MR diagnoses were confirmed with hysterosalpingography and with laparoscopy. In one case of didelphic uterus, MR images predicted the (three-dimensional helical) computer tomography (CT)-pyelographic diagnosis of renal aplasia in which the single kidney was normal. The study shows that MR is a valuable tool for the diagnosis of not only uterine anomalies but also associated anomalies in other systems.

Abnormalities, Multiple↗
PubMed2003

Gonadotrophin-releasing hormones agonist therapy increases peritoneal fibrinolytic activity and prevents adhesion formation after myomectomy.

The aim of this study was to evaluate uterine adhesions after myomectomy and peritoneal fibrinolytic capacity in women treated with gonadotrophin-releasing hormone agonist (GnRHa) before surgery. A prospective observational study comprised 15 infertile women who underwent myomectomy. Before surgery, 10 were treated with buserelin acetate (900 microg/day) for 10-12 weeks followed by additional postoperative treatment with GnRHa for 4 weeks (GnRHa group) and five received no treatment (control group). Peritoneal fluid specimens were taken at the beginning of myomectomy and the adhesions were estimated by second-look surgery (caesarean section or laparoscopy). Levels of plasminogen activator (PA) and PA inhibitor (PAI) were determined by enzyme-immunosorbent assays. Pre- and postoperative GnRHa therapy significantly reduced adhesion formation compared with control groups (adhesion scores; 0.2 +/- 0.4 vs. 2 +/- 1, P<0.0001). GnRHa group showed a significant decrease in PAI level (P<0.0001) but no significant change in PA level, suggesting increased fibrinolytic capacity in peritoneal fluid from GnRHa-treated patients. These data suggest that GnRHa therapy is successful in preventing adhesion formation after myomectomy. GnRHa-induced shift to more fibrinolytic activity, mainly because of a decreased level of PAI, may play a critical role in the mechanism of the GnRHa's action on postoperative adhesion development.

Adult↗
PubMed2001

Involvement of nitric oxide in pollen-induced biphasic nasal blockage in sensitised guinea pigs.

We have developed a reproducible allergic rhinitis model showing biphasic nasal blockage on repetitive inhalation challenge with Japanese cedar pollen in sensitised guinea pigs. The role of nitric oxide (NO) in inducing nasal blockage was evaluated with this model. N(omega)-nitro-L-arginine methyl ester (L-NAME), a non-selective NO synthase (NOS) inhibitor, intravenously administered before the challenge, significantly inhibited both early and late nasal blockage by approximately 80% and 50%, respectively. When L-NAME treatment was performed after the challenge, the late response was inhibited by approximately 70%. This inhibition was completely reversed by co-administration of L-arginine. However, aminoguanidine and L-N(6)-(1-iminoethyl)lysine, selective inhibitors of inducible NOS, negligibly influenced the degree of nasal blockage. Meanwhile, the alpha-adrenergic agonist, naphazoline, strongly suppressed both early and late nasal blockage. These results indicate that NO, likely produced by constitutive rather than inducible NOS, plays a major role in the occurrence of biphasic nasal blockage, primarily by inducing vasodilatation.

Administration, Intranasal↗