Search PubMed⌕ Search

Biomedical subjects

A Imai

Publications and source records attributed to A Imai.

At least 73 records · Page 4Linked to original sources
PubMed1999

Assessment of isoflurane-induced anesthesia in ferrets and rats.

OBJECTIVE: To characterize isoflurane (ISO)-induced anesthesia in ferrets and rats. ANIMALS: 8 ferrets (Mustela putorius furo) and 8 Sprague-Dawley rats. PROCEDURE: Ferrets and rats were anesthetized in a similar manner, using ISO in oxygen. Minimum alveolar concentration (MAC) was determined, using the tail-clamp method. Immediately thereafter, assessments were recorded for 0.8, 1.0, 1.5, and 2.0 MAC (order randomized) of ISO. RESULTS: MAC of ISO was (mean +/- SEM) 1.74 +/- 0.03 and 1.58 +/- 0.05% for ferrets and rats, respectively. Mean arterial blood pressure (MAP) was 75.0 +/- 4.3 and 107.9 +/- 2.7 mm Hg at 0.8 MAC for ferrets and rats, respectively, and decreased in a parallel dose-dependent manner. Respiratory frequency decreased in rats as ISO dose increased; however, respiratory frequency increased in ferrets as ISO dose increased from 0.8 to 1.5 MAC but then decreased at 2.0 MAC. At 0.8 MAC, hypoventilation was much greater in ferrets (PaCO2 = 71.4 +/- 3.5 mm Hg), compared with rats (PaCO2 = 57.7 +/- 1.9 mm Hg). In both species, PaCO2 progressively increased as anesthetic dose increased. Eyelid aperture of ferrets increased in a dose-dependent manner. Pupil diameter in ferrets and rats increased as ISO dose increased. CONCLUSIONS AND CLINICAL RELEVANCE: The MAP and PaCO2 in ferrets and rats and eyelid aperture in ferrets consistently and predictably changed in response to changes in anesthetic dose of ISO. Magnitude of respiratory depression was greater in ferrets than rats. Changes in MAP and PaCO2 in ferrets and rats and eyelid aperture in ferrets are consistent guides to changes in depth of ISO-induced anesthesia.

Anesthetics, Inhalation↗
PubMed1999

Comparison of clinical signs and hemodynamic variables used to monitor rabbits during halothane- and isoflurane-induced anesthesia.

OBJECTIVE: To characterize variables used to monitor rabbits during inhalation anesthesia. ANIMALS: 8 male New Zealand White rabbits. PROCEDURE: Rabbits were similarly anesthetized with halothane (HAL) or isoflurane (ISO) in a crossover study; half received HAL followed by ISO, and the protocol was reversed for the remaining rabbits. After induction, minimum alveolar concentration (MAC) was determined for each agent, using the tail-clamp method, and variables were recorded at 0.8, 1.0, 1.5, and 2.0 MAC (order randomized). RESULTS: Mean +/- SEM MAC was 1.42 +/- 0.05 and 2.07 +/- 0.09% for HAL and ISO, respectively. Directly measured auricular mean arterial blood pressure was 52.8 +/- 5.6 and 54.8 +/- 6.1 mm Hg at 0.8 MAC for HAL and ISO, respectively, and decreased from these values in a parallel dose-dependent manner. Respiratory frequency remained constant (range, 69 to 78 breaths/min) over the range of HAL doses but incrementally decreased from a mean of 53 (at 0.8 MAC) to 32 breaths/min (at 2.0 MAC) for ISO. The PaCO2 was similar at 0.8 MAC for HAL and ISO and progressively increased with increasing doses of both agents; PaCO2 at 2.0 MAC for ISO was significantly greater than that at 2.0 MAC for HAL (79.8 +/- 13.7 vs 54.9 +/- 4.0 mm Hg, respectively). Eyelid aperture consistently increased in a dose-dependent manner for both anesthetics. CONCLUSIONS: Arterial blood pressure, PaCO2, and eyelid aperture consistently and predictably changed in rabbits in response to changes in anesthetic doses. The magnitude of respiratory depression was greater for ISO than for HAL.

Anesthesia, Inhalation↗
PubMed1998

High dose rate versus low dose rate interstitial radiotherapy for carcinoma of the floor of mouth.

PURPOSE: Patients with cancer of the floor of mouth are treated with radiation because of functional and cosmetic reasons. We evaluate the treatment results of high dose rate (HDR) and low dose rate (LDR) interstitial radiation for cancer of the floor of mouth. METHODS AND MATERIALS: From January 1980 through March 1996, 41 patients with cancer of the floor of mouth were treated with LDR interstitial radiation using 198Au grains, and from April 1992 through March 1996 16 patients with HDR interstitial radiation. There were 26 T1 tumors, 30 T2 tumors, and 1 T3 tumor. For 21 patients treated with interstitial radiation alone, a total radiation dose of interstitial therapy was 60 Gy/10 fractions/6-7 days in HDR and 85 Gy within 1 week in LDR. For 36 patients treated with a combination therapy, a total dose of 30 to 40 Gy of external radiation and a total dose of 48 Gy/8 fractions/5-6 days in HDR or 65 Gy within 1 week in LDR were delivered. RESULTS: Two- and 5-year local control rates of patients treated with HDR interstitial radiation were 94% and 94%, and those with LDR were 75% and 69%, respectively. Local control rate of patients treated with HDR brachytherapy was slightly higher than that with 198Au grains (p = 0.113). For late complication, bone exposure or ulcer occurred in 6 of 16 (38%) patients treated with HDR and 13 of 41 (32%) patients treated with LDR. CONCLUSION: HDR fractionated interstitial brachytherapy can be an alternative to LDR brachytherapy for cancer of the floor of mouth and eliminate radiation exposure for the medical staff.

Adult↗
PubMed1998

Preterm labor and bacterial intra-amniotic infection: arachidonic acid liberation by phospholipase A2 of Prevotella bivia.

There is a strong association between preterm labor and infection, presumably through an increase in prostaglandin formation. The studies presented in this report were undertaken to evaluate whether Prevotella bivia, a common anaerobic isolate of intrauterine infection, stimulates arachidonic acid metabolism, as a rate-limiting step for prostaglandin synthesis in the human uterine endometrium. When human uterine endometrial cells prelabeled with [3H]arachidonic acid to an isotopically steady state were exposed to an extract of P. bivia, arachidonic acid liberation was stimulated, accompanied by lysophospholipid formation. Similar stimulatory effect on phospholipid degradation was also observed in the experiment with the bacterial conditioned media which was spent as culture media. These results suggests that P. bivia stimulates endometrial phospholipid metabolism, related with activity of phospholipase A2, which might induce the onset of labor associated with intra-amniotic infection.

Journal Article↗
PubMed1998

Preterm labor and bacterial intraamniotic infection: arachidonic acid liberation by phospholipase A2 of Fusobacterium nucleatum.

OBJECTIVE: The studies presented in this report were undertaken to evaluate whether Fusobacterium nucleatum, a common anaerobic isolate in intrauterine infection, stimulates arachidonic acid metabolism, a rate-limiting step for prostaglandin synthesis, in the human uterine endometrium. STUDY DESIGN: Effects of F nucleatum on arachidonic acid liberation from human uterine endometrial cells and of F nucleatum extract on lysophosphatidylcholine production in human uterine endometrial cells were investigated. RESULTS: When human uterine endometrial cells labeled with tritiated arachidonic acid to an isotopically steady state were exposed to an extract of F nucleatum, arachidonic acid liberation was stimulated, accompanied by lysophospholipid formation. Similar stimulatory effects on phospholipid degradation were also observed in the experiment with bacterially conditioned media. CONCLUSIONS: These results suggest that F nucleatum stimulates endometrial phospholipid metabolism, related to activity of phospholipase A2, which might induce the onset of labor associated with intraamniotic infection.

Arachidonic Acid↗
PubMed1998

A gonadotropin-releasing hormone analogue impairs glucose tolerance in a diabetic patient.

Changes in serum glucose levels were examined in a female with insulin-independent diabetes who received a gonadotropin-releasing hormone (GnRH) analog treatment for pelvic endometriosis. The mean blood glucose levels were higher on busereline therapy, and higher levels of hemoglobin A1c were noted on busereline therapy (range 6.9-12.5%) versus pre- and post-treatment (range 5.1-5.9%). Hormonal alteration induced by GnRH analog treatment may impair glucose tolerance.

Adult↗
PubMed1998

Drastic elevation of serum CA125, CA72-4 and CA19-9 levels during menses in a patient with probable endometriosis.

Levels of CA125, CA72-4 and CA19-9, serum markers for ovarian cancer, were measured throughout menstrual cycles in a patient with probable pelvic endometriosis. The patient had CA125 levels >1000 U ml(-1), CA72-4>10 U ml(-1) and CA19-9>150 U ml(-1) during but not after menses (P<0.01). In luteal phase and premenstrual phase, the levels of these markers seemed to return normal ranges, although CA125 remained over the upper normal limit. Knowledge that a physiological elevation of these markers may occur during menses might avoid misinterpretation.

Adnexal Diseases↗
PubMed1998

Prediction of patients with higher order multifetal pregnancy at risk for postpartum pulmonary edema.

OBJECTIVE: This retrospective study aims to verify the factors for the development of maternal pulmonary edema in higher order multifetal pregnancy. STUDY DESIGN: We analyzed medical profiles of a total of 13 triplet, quadruplet and quintuplet pregnancies for the years 1992 through 1997. Some treatments were applied in attempts to promote these multifetal pregnancies. All underwent cesarean section, two of which developed pulmonary edema within a few hours of delivery. There had been no evidence for the development of pulmonary edema antepartum. RESULTS: In the patients affected by pulmonary edema, postoperative values of PaO2/FIO2<250 mmHg showed close association to a value perioperative fluid loading index (FLI)>0; the index consists of an intraoperative fluid balance and preoperative infusion volume within 24 h prior to surgery. Two patients with postoperative pulmonary edema had a perioperative FLI>0, whereas the others had values 0 may have a much higher risk for postoperative pulmonary edema, suggesting the predictive role of the perioperative FLI value.

Adult↗
PubMed1998

Congenital ectopic nail with bone deformity.

This report describes two cases of congenital ectopic nail with bone deformity. Histologically, the squamous epithelium of the nail matrix lacked a definite granular layer. Resected nail tissue was connected with the periosteum of the tip of the ungual phalanx, which suggested that the contact of the ectopic nail matrix with the periosteum could impede intramembranous ossification and deform the bone shape.

Child↗
PubMed1998

Evidence for tight coupling of gonadotropin-releasing hormone receptor to stimulated Fas ligand expression in reproductive tract tumors: possible mechanism for hormonal control of apoptotic cell death.

Fas ligand induces cell death by means of apoptosis in a variety of cell types when cross-linked with its natural receptor, Fas. GnRH receptor-bearing tumors undergo apoptosis in vivo and in vitro with GnRH agonists. To provide a potential association of the Fas system with the antiproliferative signaling process of GnRH receptor, we have evaluated the regulation of Fas ligand expression in GnRH receptor-positive tumors and cloned cell lines known to have substantial GnRH receptors. Surgically removed uterine endometrial carcinomas and ovarian carcinomas had been screened for GnRH receptor expression before analysis. Fas ligand protein was characterized by immunoblotting of membrane proteins with the specific antibody. Fas ligand messenger RNA was determined by RT-PCR using oligonucleotide primers synthesized according to the published Fas ligand sequence. Incubation with a GnRH analog (1 mumol/L) induced the expression of Fas ligand messenger RNA and immuno-reactive Fas ligand with a lag time of 48 h in cloned cell lines (endometrial carcinoma HHUA cells, and ovarian carcinoma SK-OV-3 and Caov-3 cells). There was no detectable Fas ligand expression within 24 h. The stimulatory effect of GnRH on Fas ligand protein expression revealed a dose dependency; a half-maximal effect occurred with 10 nmol/L GnRH analog (P < 0.01). The stimulated Fas ligand expression could be neutralized by displacement of GnRH from its receptor by GnRH antagonist antide. Cells isolated from GnRH receptor-bearing ovarian carcinomas and uterine endometrial carcinomas gave identical results to those obtained in cloned cell lines. These data demonstrate the functional coupling of stimulated Fas ligand expression to GnRH receptor activation. Increased Fas ligand level within the GnRH receptor-bearing tumors might promote apoptotic cell death through attack on intratumoral Fas-positive cells that could, at least in part, account for the antiproliferative action of the hormone.

Apoptosis↗
PubMed1998

Influence of thiouracil-induced hypothyroidism on adrenal and gonadal functions in adult female rats.

The effect of hypothyroidism on adrenals and gonads in adult female rats was investigated throughout the estrous cycle. Hypothyroidism was induced by administration of 4-Methyl-2-Thiouracil (Thiouracil) in the drinking water. The weight of ovaries and adrenals, and the plasma levels of corticosterone decreased in hypothyroid rats as compared with euthyroid rats throughout the estrous cycle. Hypothyroidism resulted in decreased concentrations of plasma LH on the day of diestrus and proestrus, whereas the plasma concentrations of prolactin and progesterone increased as compared with euthyroid rats. The weight of uteri and plasma concentrations of estradiol decreased during the day of diestrus and proestrus in hypothyroid rats as compared with euthyroid rats. To further clarify the dysfunction of hypothalamo-hypophysial-adrenal axis in hypothyroid rats, animals were stressed by immobilization for 3 hr. In hypothyroid rats, a marked increase in plasma levels of ACTH in response to immobilization stress was observed compared to euthyroid control, whereas increases in plasma concentrations of corticosterone were much smaller in hypothyroid than euthyroid rats. These results clearly indicate that hypothyroidism causes both gonadal and adrenal disturbances in adult female rats. The increased concentrations of plasma progesterone may be due to hypersecretion of prolactin during the day of proestrus and estrus, which in turn result in disruption of the estrous cycle.

Adrenal Glands↗
PubMed1998

Epitope analysis of staphylococcal enterotoxin A using different synthetic peptides.

The antigenic determinants (or epitopes) of staphylococcal enterotoxin A (SEA) were analyzed using synthetic peptides and rabbit antibodies to their corresponding peptides. Of 12 different synthetic peptides tested, peptides A-1 (corresponding to the amino acid sequence 1-20), A-5 (81-100), and A-8 (141-160) were reactive with anti-SEA antibodies. However, all synthetic peptides were found to elicit antibodies reactive with native SEA molecule. These findings suggest that native SEA molecule contains at least 3 different antigenic determinants.

Animals↗
PubMed1998

Fas and Fas ligand system may mediate antiproliferative activity of gonadotropin-releasing hormone receptor in endometrial cancer cells.

Gonadotropin-releasing hormone (GnRH) receptor-bearing tumors undergo apoptosis in vivo and in vitro with GnRH analogs. We recently showed that GnRH stimulation induces intratumoral expression of the apoptosis-inducing Fas ligand in human reproductive tract tumors. To provide a potential association of Fas/Fas ligand system with the antiproliferative signaling process of GnRH receptor, we evaluated a correlation between the Fas ligand expression and the number of viable cells in two types of GnRH receptor-bearing endometrial carcinomas that differ in Fas content. Surgically removed uterine endometrial carcinomas had been screened for the presence of GnRH receptor and Fas before analyses. Fas ligand protein was characterized by immunoblotting of membrane proteins with the specific antibody. After a lag time of 2 days, incubation with a GnRH analog leuprolide (10 microM) induced significant growth inhibition of the Fas- and GnRH receptor-bearing cells (p<0.01). Time course analysis showed that Fas ligand production, which was already observed at day 2 (p<0.01), precedes the onset of reduction in viable cell number. The stimulatory effect of GnRH on Fas ligand expression and reduction of viable cells revealed dose-dependency. The analog at concentration of 10 microM induced up to 90% reduction in cell number. In contrast, the growth of Fas-negative cells was not affected by the analog, although Fas ligand appeared in response to the GnRH analog (p<0.01). These data demonstrate that the co-presence of Fas could be essential for GnRH to promote antiproliferative action in endometrial cancer cells carrying GnRH receptor. The hormone may act through intratumor Fas and Fas ligand system to induced growth inhibition in GnRH-sensitive tumors.

Adenocarcinoma↗
PubMed1998

The stress-bearing ability of mucosa in complete denture-wearers.

OBJECTIVE: The purpose of this study was to investigate the stress-bearing ability of mucosa in complete denture-wearers. METHODS: The maximum bite force (MBF) was obtained in 31 voluntary complete denture-wearers with a miniature bite force instrument and a set of central bearing devices. The projective stress-bearing area in the mandible (PAM) was measured through the impression surface of the mandibular complete denture. The authors evaluated the stress-bearing ability (SBA) of mucosa in complete denture-wearers by the formula MBF/PAM. RESULTS: The results showed that there was a significant positive correlation between the MBF (the mean was 15.13 kg in men and 11.39 kg in women) and the PAM (the mean was 17.15 cm2 in men and 14.46 cm2 in women) and that there was no significant difference between the mean of the SBA in men (0.89 kg/cm2) and the mean of the SBA in women (0.79 kg/cm2). The mean value of the maximum pressure borne by the mandibular edentulous region was 82 kPa (0.84 kg/cm2). CONCLUSIONS: The SBA may become a valuable parameter for the design of both occlusion and reinforcement in the denture construction and for the selection of the maximum load in mechanical tests of complete dentures.

Aged↗
PubMed1997

Gi protein activation of gonadotropin-releasing hormone-mediated protein dephosphorylation in human endometrial carcinoma.

OBJECTIVE: Gonadotropin-releasing hormone receptor is demonstrated in uterine endometrial carcinomas. This study was performed to determine gonadotropin-releasing hormone receptor-mediated membrane events and to identify the guanosine triphosphate binding protein (G protein) subtypes linked to gonadotropin-releasing hormone receptor in the tumors. STUDY DESIGN: Endometrial carcinomas surgically removed had been screened for gonadotropin-releasing hormone receptor expression before plasma membrane isolation. The phosphoprotein level was observed in the phosphorus 32-labeled incorporation from [gamma-32P]adenosine triphosphate into the isolated plasma membranes. The Gi (alpha subunit) protein was detected by immunoblotting and pertussis toxin-catalyzed adenosine diphosphate ribosylation. RESULTS: Incubation of phosphorus 32-labeled membranes with a gonadotropin-releasing hormone analog in the presence of guanosine thiotriphosphate caused a remarkable loss of phosphoprotein from 35 kd protein. This dephosphorylation action was dose dependent of the gonadotropin-releasing hormone analog, and the maximal effect (90% loss) occurred at 100 nmol/L. Pertussis toxin brought about adenosine diphosphate ribosylation of an immunodetected G alpha i. Gonadotropin-releasing hormone analog alone or guanosine thiotriphosphate alone had no effect. Pretreatment of the membrane with the pertussis toxin completely inhibited gonadotropin-releasing hormone-mediated dephosphorylation of the 35 kd protein. CONCLUSION: These data demonstrate the coupling of gonadotropin-releasing hormone receptor to protein dephosphorylation through Gi, raising the possibility that the antimitogenic action of gonadotropin-releasing hormone may occur by release of the action of protein phosphorylation to promote cell growth.

Adenosine Diphosphate Ribose↗
PubMed1997

Frequent expression of Fas in gonadotropin-releasing hormone receptor-bearing tumors.

OBJECTIVE: Fas, a cell surface receptor, mediates cell death by means of apoptosis in a variety of cell types. Gonadotropin-releasing hormone (GnRH) receptor-bearing tumors undergo the apoptosis with GnRH analogs. The authors attempted to determine the frequency with which Fas is present in the GnRH receptor-bearing tumors. STUDY DESIGN: Surgically removed gynecological tumors were screened for GnRH receptor expression prior to analyses. Fas was characterized by immunoblotting of membrane proteins with the specific antibodies. Fas messenger ribonucleic acid (mRNA) was determined by reverse transcription-polymerase chain reaction using oligonucleotide primers synthesized according to the published Fas sequence. RESULTS: Immunoreactive Fas and Fas mRNA were detected in a high proportion (94.4%) of the specimens from endometrial carcinomas (8 of 9), ovarian carcinomas (7 of 7), and uterine leiomyosarcomas (2 of 2); all these expressed GnRH receptor. There was neither substantial Fas nor GnRH receptor in 9 cervical carcinomas. Cloned cell lines gave identical results to those obtained in their respective mother tumors. CONCLUSION: These data might suggest the frequent expression of Fas in the GnRH receptor-bearing tumors, but not in the GnRH receptor-negative tumors. Despite a poorly understood processes of apoptosis at present, there may be at least some similarity in signal transduction pathway utilized by GnRH analogs and Fas ligands.

Adenocarcinoma↗
PubMed1997

The role of transforming growth factor-beta in PEG-rHuMGDF-induced reversible myelofibrosis in rats.

Pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF) injected at a suprapharmacologic dose (100 microg/kg) daily for 5 d in normal rats caused marked increases in marrow megakaryocytes and platelet counts at 6-8 d followed by gradual decreases to control levels at 10-20 d. Interestingly, in addition to the expected thrombopoiesis, PEG-rHuMGDF was associated with myelofibrosis with a predominance of reticulin fibres at day 10 followed by complete normalization by day 20. At 6-8 d, the levels of transforming growth factor-beta1 (TGF-beta1) in the extracellular fluid of the marrow, the platelet poor plasma, and the platelet extract were increased 23-, 7- and 2-fold, respectively. The elevated levels of TGF-beta1 were gradually reduced to baseline levels at 13-20 d in accordance with the normalization of myelofibrosis and thrombopoiesis. An ultrastructural analysis showed that large fragments of megakaryocytes were deposited in the marrow parenchyma of PEG-rHuMGDF-treated rats at day 6. PEG-rHuMGDF administration at pharmacologic doses (1 and 10 microg/kg) did not induce the deposition of reticulin fibres in the marrow. These findings suggest that TGF-beta1 leaked from megakaryocytes is involved in the development of the PEG-rHuMGDF-induced myelofibrosis and that this is a reversible process related to the regulation of the excess production of platelets.

Animals↗