Biomedical subjects

Toshiro Kubota

Publications and source records attributed to Toshiro Kubota.

10 recordsLinked to original sources

PubMed2006

Transient ADC change precedes persistent neuronal death in hypoxic-ischemic model in immature rats.

A brief ischemia causes delayed neuronal death (DND) in some areas vulnerable to ischemia. Additionally, it causes a transient reduction in the apparent diffusion coefficients (ADCs) obtained from diffusion-weighted magnetic resonance imaging (DWI), which is a powerful tool to detect ischemic changes in the brain at a very early stage. The present study examined long-term histopathological changes in the hippocampal neurons up to 30 days after a very mild hypoxic-ischemic (HI) insult in immature rats. Three-week-old male rats were subjected to 15- and 30-min HI insults (15-min HI and 30-min HI) and serial DWI was performed. Only animals whose ADC reduction pattern was transient were examined histopathologically. ADCs decreased significantly during the insult, and the ADC values of 30-min HI group were significantly lower than those of 15-min HI group. Ischemic neuronal changes were observed up to 30 days after the insult in 30-min HI group, although ADCs in the chronic stage were within the normal range. In addition, neuron density in 30-min HI group was significantly lower in the chronic stage (on days 14 and 30) than in 15-min HI group. A very mild hypoxia-ischemia followed by a transient ADC reduction causes persistent neuronal death, which can be predicted by measuring ADCs during the acute insult.

Animals↗

PubMed2006

Dysembryoplastic neuroepithelial tumor in pregnancy.

BACKGROUND: Dysembryoplastic neuroepithelial tumor is a rare, low-grade brain tumor that is characterized by intractable, partial seizures of juvenile onset. CASE: A 36-year-old pregnant woman with dichorionic, diamniotic twins temporarily lost consciousness at 27 weeks of gestation. Magnetic resonance imaging evaluation showed a 3-cm multicystic nodule in her right temporal lobe that was diagnosed, together with her history of recurrent anxiety attacks, as dysembryoplastic neuroepithelial tumor. The lesion did not enlarge during pregnancy, and healthy male infants were delivered by cesarean at 36 weeks. The tumor was successfully removed 2 months postpartum, and the patient has experienced no further seizures. CONCLUSION: Dysembryoplastic neuroepithelial tumor was conservatively managed during pregnancy without neurosurgical intervention.

Adult↗

PubMed2006

[Sheehan syndrome].

Explore the source record for details and available documents.

Diagnostic Imaging↗

PubMed2005

Change in prostaglandin E synthases (PGESs) in microsomal PGES-1 knockout mice in a preterm delivery model.

Most preterm deliveries are associated with infection and inflammation. Prostaglandin E2 (PGE2) is one of the most important mediators in the processes of inflammation, and is converted from PGH2 by various kinds of PGE synthases (PGESs). Among PGESs, microsomal PGES-1 (mPGES-1) is known to be the most important subtype in the processes of inflammation. To evaluate the role of PGESs in preterm delivery, we used mPGES-1 knockout mice in a lipopolysaccharide (LPS)-induced preterm labor model. Unexpectedly, the duration of labor after LPS treatment was not statistically different between C57BL6 wild-type mice and mPGES-1 knockout mice. In wild-type mice, mPGES-1 mRNA and protein expression increased in the myometrium and fetal membrane after LPS treatment. In contrast, the expression of mPGES-2 or cytosolic PGES was not changed by LPS treatment. On mPGES-1 knockout mice, mPGES-2 increased by LPS treatment in myometrium. The present data indicate that mPGES-1 may be involved in LPS-induced preterm labor, but inhibition of mPGES-1 alone may not prevent preterm delivery, because mPGES-2 might compensate for the role of mPGES-1.

Animals↗

PubMed2004

Massively parallel networks for edge localization and contour integration--adaptable relaxation approach.

The paper describes a new adaptive neural network for edge-based pattern extraction problems. In the model, each neuron represents an edge with continuous state variables describing its location and orientation. The post-synaptic distribution is dependent on the state variables. Each neuron adjusts its state to increase its membrane potential, which results in highly adaptive dynamics of the synaptic weight distribution. The network allocates multiple neurons with different orientation modes for each edge. The strategy allows accurate modeling of multi-modal distributions at key-points such as corners and junctions. As a result, the network delineates edges at sub-pixel accuracy while preserving key-points. It is also capable of processing a sequence of images and following moving objects. The network is extended for contour integration and key-point detection tasks. The paper presents experiments conducted on both synthetic and non-synthetic data to demonstrate the effectiveness of the technique.

Artificial Intelligence↗

PubMed2004

Haem oxygenase augments porcine granulosa cell apoptosis in vitro.

Haem oxygenases produce carbon monoxide, which, like nitric oxide, is a gaseous messenger molecule that is one of several important survival factors in ovarian follicles. However, little is known about the expression and possible functions of these enzymes in granulosa cells. The purpose of this study was to investigate the expression and possible role of haem oxygenases in porcine granulosa cells (PGCs). We obtained frozen sections of porcine ovaries and PGCs from ovarian follicles of various sizes by needle aspiration, and examined the expression of haem oxygenase-1 (HO-1; inducible type) and HO-2 (constitutive type) in PGCs by immunohistochemistry, RT-PCR, western blotting and flow cytometry. Both types of haem oxygenase were identified in PGCs throughout follicular development, but HO-1 was expressed primarily in granulosa cells in atretic follicles. We also investigated the effect of haem oxygenases on apoptosis of granulosa cells (flow cytometry to detect subdiploid DNA fluorescence) and on expression of Fas ligand (quantitative analysis of western blotting and flow cytometry). In tightly bound PGCs, the mean proportion of apoptotic cells treated with 1 microM haemin (a haem oxygenase substrate) was approximately 1.7-fold greater than that in untreated controls, and zinc protoporphyrin IX (ZnPP IX; a haem oxygenase inhibitor) completely inhibited the increase in apoptosis induced by haemin in 24-h culture. Conversely, in weakly associated PGCs, the proportion of apoptotic cells was not altered by haemin. The quantity of Fas ligand protein was increased in a dose-dependent manner in tightly bound PGCs treated with haemin compared with controls, and the haemin-induced increase in Fas ligand protein was inhibited by ZnPP IX. Thus we identified inducible HO-1 and constitutive HO-2 in PGCs throughout follicular development, and we conclude that products of reactions catalysed by haem oxygenases are likely to be important autocrine/paracrine factors that regulate apoptosis in PGCs.

Animals↗

PubMed2004

Estrogen and progesterone improve scopolamine-induced impairment of spatial memory.

This study was conducted to investigate the effects of estrogen and progesterone on spatial memory in ovariectomized female rats, specifically, on memory impaired by the cholinergic antagonist scopolamine. Forty-one female rats were divided into five groups: ovariectomized (OVX), estrogen-treated after ovariectomy (OE), progesterone-treated after ovariectomy (OP), estrogen-progesterone-treated after ovariectomy (OEP), and the sham control group (Control). The animals were trained on an eight-arm radial maze with four arms baited to assess both working and reference memory performances. The OE and OEP groups showed significant improvement in the ability to perform a spatial memory task over the OVX group (P<0.05). Spatial memory in the OP group did not differ from that in the OVX group. After thirty-two trials were conducted and all rats learned the eight-radial maze task, scopolamine hydrobromide (0.2 mg/kg i.p.) was administered prior to retesting. After scopolamine injection, the OVX group showed an increased number of working memory errors, reference memory errors than the other groups (P<0.05). The OE, OEP and OP groups showed significant improvement in spatial impairment induced by scopolamine. These findings suggest progesterone alone or in combination with estrogen, improved scopolamine-induced impairment of working memory and reference memory as effectively as estrogen supplementation.

Analysis of Variance↗

PubMed2002

Usefulness of CA19-9 versus CA125 for the diagnosis of endometriosis.

OBJECTIVE: To investigate the clinical value of the serum CA19-9 level in comparison with the serum CA125 level for diagnosing and determining the severity of endometriosis. DESIGN: Retrospective study. SETTING: Department of Comprehensive Reproductive Medicine in a university hospital. PATIENT(S): One hundred one women with endometriosis and 22 without endometriosis participated in this study. INTERVENTION(S): Blood samples were collected before the operation (laparoscopy, oophrectomy, cystectomy, and/or hysterectomy), and tissue samples of ovarian chocolate cysts were collected during the operation. MAIN OUTCOME MEASURE(S): The serum CA19-9 and CA125 levels and the localization of these antigens in ovarian chocolate cysts. RESULT(S): The mean serum CA19-9 levels in patients at all stages of endometriosis were significantly higher than those in patients without endometriosis, and serum CA19-9 levels significantly correlated with the Revised American Fertility Society classification scores. Intense staining of CA19-9 was observed in 15 of the 20 samples of ovarian chocolate cysts. CONCLUSION(S): CA19-9 is a useful marker for determining the severity of endometriosis.

Adult↗

PubMedDate not supplied

Probucol, a hypocholesterolemic agent, prevents the development of uterine adenomyosis induced by pituitary grafting in mice.

This in vivo experimental study was designed to investigate the effects of probucol, a hypocholesterolemic agent, on uterine adenomyosis which is frequently induced by pituitary grafting in mice. SHN mice, which are known to develop uterine adenomyosis spontaneously, and much sooner after pituitary grafting, were used and histopathological study on the uteri in pituitary gland-implanted mice with or without probucol treatment was performed. Four out of 10 pituitary gland-implanted mice developed uterine adenomyosis with dilated blood vessels, but none of the probucol-treated mice. There were no differences between pituitary-grafted mice with or without probucol treatment in body weight and wet weights of uterus, ovaries, kidney and liver except spleen. Probucol markedly reduced the serum levels of total cholesterol, free cholesterol, free fatty acids, phospholipids and triglycerides and, thus, this agent inhibited the incidence of uterine adenomyosis induced by pituitary grafting in mice.

Animals↗

PubMedDate not supplied

Androgenic effects on adrenocortical responsiveness in neonatal rats.

We are increasingly exposed to environmental and occupational hazardous chemicals, which modulate hormonal activity and/or mutagenicity in mammals. In the present study, we investigated the effects of sex-steroid hormones on adrenocortical responsiveness to adrenocorticotropic hormone (ACTH) in neonatal rats. The levels of corticosterone increased with the dose of ACTH in adrenal cells of males and females in vitro. Although castration markedly augmented the responsiveness in male rats, testosterone-replacement in the castrated male rats inhibited the enhancement and, furthermore, the treatment with testosterone suppressed the responsiveness in 14-day-old intact female rats, too. Castration enhanced the level of ACTH receptor mRNA to 3-fold of that in intact male rats at 14 days of age, but replacement treatment with testosterone in castrated male rats lowered the elevated levels. These findings suggest that: 1) the hyporesponsiveness of adrenocorticosteroid in the stress hyporesponsive period of neonates might be dependent on the reduction of ACTH receptor mRNA, and 2) endocrine-disrupting chemicals, with characters of androgens, estrogens or gonadotropin-releasing hormones, might affect the responsiveness to ACTH and the ACTH receptor mRNA expression levels in adrenal cells of neonates.

Adrenal Cortex↗