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Y Okada

Publications and source records attributed to Y Okada.

At least 55 records · Page 3Linked to original sources
PubMed2003

Evaluation of neuronal cell death after a new global ischemia model in infant mice.

For the first time we set up a new model for global ischemia in the infant mice, and time-dependent changes of the blood-brain barrier (BBB) disruption and neuronal cell death were investigated in detail. Infant C57/B16 mice (postnatal 13 days) were anesthetized with inhalation of sevoflurane in N2O/O2 (70/30%) and were subjected to global ischemia by bilateral common carotid artery occlusion (CCAO) for 25 minutes. Disruption of BBB was noted at 4 hours and increased up to 24 hours after the injection of 2% Evan's Blue in the transient CCAO (tCCAO) model. Evaluation of neuronal cell death was determined with toluidine blue staining. Morphological changes of neurons after tCCAO were clearly observed in the hippocampal CA1 region but were slightly detected in the CA3 region. However, there were no morphological changes in the hippocampal dentate gyrus, the neocortex, the striatum and the hypothalamus. The number of survival neurons in the CA1 was significantly decreased at 2 days and sustained up to 4 days after tCCAO. These data indicate that this method is very useful to induce selective vulnerability in mouse hippocampus, and it provides a reliable ischemic model in infant mice.

Animals↗
PubMed2003

Simple techniques for atraumatic peritoneal dissection from the abdominal wall and for preventing peritoneal injury during trocar placement under retroperitoneoscopy.

PURPOSE: Inadvertent peritoneal tearing causes pneumoperitoneum and makes retroperitoneal laparoscopic procedures technically more difficult. We describe some simple techniques of atraumatic peritoneal dissection and the prevention of peritoneal injury during trocar placement under retroperitoneoscopic guidance. MATERIALS AND METHODS: After balloon dilation and the establishment of pneumoretroperitoneum a laparoscopic swab stick was used for peritoneal dissection from the abdominal wall under retroperitoneoscopic guidance. Exploratory puncture using a Cathelin (Terumo, Tokyo, Japan) needle was performed before trocar placement in close proximity to the lateral peritoneal reflection. RESULTS: We applied this technique in our last 10 consecutive retroperitoneal laparoscopic procedures. No peritoneal rents occurred during dissection of the lateral peritoneal reflection or trocar insertion. CONCLUSIONS: The laparoscopic swab stick technique described facilitates atraumatic peritoneal dissection as well as creation of an adequate working space. Exploratory puncture using a Cathelin needle is useful for preventing inadvertent peritoneal injury during trocar placement.

Abdominal Wall↗
PubMed2003

Disturbance of neural respiratory control in neonatal mice lacking GABA synthesizing enzyme 67-kDa isoform of glutamic acid decarboxylase.

To examine the role of GABA in the respiratory rhythm and pattern generation in neonatal mice, we analyzed the function of the respiratory control system of 67-kDa isoform of glutamic acid decarboxylase (GAD67)-deficient neonatal mice. In these mutant (GAD67-/-) mice, GABA levels in the brainstem were reduced to about 30% of those in wild-type (GAD67+/+) mice. In in vivo preparations, ventilatory parameters were analyzed by whole body plethysmography and electromyography of intercostal muscles. GAD67-/- mice exhibited abnormal respiratory patterns, i.e. irregular respiratory rhythm, and periodic gasp-like respiration followed by shallow breathing with short inspiratory duration and apnea. In in vitro GAD67-/- brainstem-spinal cord preparations, inspiratory C4 burst duration was shorter than that in GAD67+/+ preparations. Whole cell recordings revealed that activities of inspiratory neurons in the ventral medulla of GAD67-/- mice were characterized by a short depolarization period and a paucity of firing during the inspiratory phase. Superfusion of the in vitro GAD67-/- preparation with 10 microM GABA prolonged C4 burst duration and partly restored a normal pattern of inspiration, although the restoration was limited. These results indicate that reduced GABA levels during the perinatal period induce malfunction in the respiratory control system. We suggest that GABAergic transmission is not essential for basic respiratory rhythm generation but plays an important role in the maintenance of regular respiratory rhythm and normal inspiratory pattern in neonatal mice.

Animals↗
PubMed2003

Apoptotic and necrotic blebs in epithelial cells display similar neck diameters but different kinase dependency.

Apoptotic and necrotic blebs elicited by H(2)O(2) were compared in terms of dynamics, structure and underlying biochemistry in HeLa cells and Clone 9 cells. Apoptotic blebs appeared in a few minutes and required micromolar peroxide concentrations. Necrotic blebs appeared much later, prior to cell permeabilization, and required millimolar peroxide concentrations. Strikingly, necrotic blebs grew at a constant rate, which was unaffected throughout successive cycles of budding and detachment. At 1 microm diameter, the necks of necrotic and apoptotic blebs were almost identical. ATP depletion was discarded as a major factor for both types of bleb. Inhibition of ROCK-I, MLCK and p38MAPK strongly decreased apoptotic blebbing but had no effect on necrotic blebbing. Taken together, these data suggest the existence of a novel structure of fixed dimensions at the neck of both types of plasma membrane blebs in epithelial cells. However, necrotic blebs can be distinguished from apoptotic blebs in their susceptibility to actomyosin kinase inhibition.

Actomyosin↗
PubMed2003

Gut overgrowth with abnormal flora: the missing link in parenteral nutrition-related sepsis in surgical neonates.

BACKGROUND AND AIMS: Patients receiving parenteral nutrition are at risk of septicaemia. Intestinal dysmotility and impaired gut immunity due to parenteral nutrition promote bacterial overgrowth. Gut overgrowth with aerobic Gram-negative bacilli (AGNB) impairs systemic immunity. The aim of this study was to determine the potential role of gut overgrowth with AGNB in the pathogenesis of septicaemia related to parenteral nutrition. METHODS: A prospective 5 y study of surgical infants less than 6 months of age was undertaken. Surveillance samples of the oropharynx and gut were obtained at the start of parenteral nutrition and thereafter twice weekly, to detect AGNB carriage. Blood cultures were taken on clinical indication only. RESULTS: Two-hundred and eight infants received parenteral nutrition for 6271 days (median 13 days, range 1-512 days). The incidence of AGNB carriage was 42%, whilst the septicaemia rate was 15%. Eighty-four percent of septicaemic infants carried AGNB, whilst 16% never carried AGNB (P<0.005). Carriage developed significantly earlier than septicaemia. CONCLUSIONS: The incidence of septicaemia was significantly greater in the subset of abnormal carriers. Although gut overgrowth with abnormal flora reflects illness severity, the fact that it preceded septicaemia implicates AGNB overgrowth, per se, as a contributory factor in the development of septicaemia related to parenteral nutrition. Prevention is unlikely to be successful if it ignores the abnormal flora.

Bacteremia↗
PubMed2003

An investigation of adverse effects caused by the injection of high-dose TNFalpha-expressing adenovirus vector into established murine melanoma.

We previously reported that RGD fiber-mutant adenovirus vector carrying human TNFalpha cDNA (AdRGD-TNFalpha) could more effectively induce mouse B16 BL6 melanoma regression than conventional Ad-TNFalpha on intratumoral injection at less than 10(9) vector particles (VP). Although mice treated with either Ad type at 10(10) VP showed remarkable tumor regression due to hemolytic necrosis, severe adverse effects including extreme reduction in body weight were also induced by Ad treatment. Here, we attempted to elucidate the cause of the adverse effects to optimize the application of AdRGD-TNFalpha. More than 99% of systemically administered Ad accumulated in the liver, and the rate of Ad leakage into systemic circulation from the B16 BL6 tumors injected with AdRGD or conventional Ad at 10(10) VP was about 1% of the administered VP. Although the leaked Ad did not directly induce hepatotoxicity or body weight reduction, excessive TNFalpha produced in the tumors leaked into the blood at high concentrations and caused systemic inflammation, tissue denaturation, and body weight reduction in mice injected intratumorally with AdRGD-TNFalpha or Ad-TNFalpha at 10(10) VP. Our results demonstrated that an exact AdRGD-TNFalpha dosage must be determined to prevent TNFalpha leakage from tumors into systemic circulation, thereby enabling safe application of AdRGD-TNFalpha to clinical melanoma gene therapy in the future.

Adenoviridae↗
PubMed2003

Dendritic cells transduced with gp100 gene by RGD fiber-mutant adenovirus vectors are highly efficacious in generating anti-B16BL6 melanoma immunity in mice.

Dendritic cells (DCs) are the most potent professional antigen-presenting cells for the initiation of antigen-specific immune responses, and antigen-loaded DCs have been regarded as promising vaccines in cancer immunotherapy. We previously demonstrated that RGD fiber-mutant adenovirus vector (AdRGD) could attain highly efficient gene transduction into human and murine DCs. The aim of the present study is to demonstrate the predominance of ex vivo genetic DC manipulation using AdRGD in improving the efficacy of DC-based immunotherapy targeting gp100, a melanoma-associated antigen (MAA). Vaccination with murine bone marrow-derived DCs transduced with AdRGD encoding gp100 (AdRGD-gp100/mBM-DCs) dramatically improved resistance to B16BL6 melanoma challenge and pulmonary metastasis as compared with immunization with conventional Ad-gp100-transduced mBM-DCs. The improvement in antimelanoma effects upon immunization with AdRGD-gp100/mBM-DCs correlated with enhanced cytotoxic activities of natural killer (NK) cells and B16BL6-specific cytotoxic T lymphocytes (CTLs). Furthermore, in vivo depletion analysis demonstrated that CD8(+) CTLs and NK cells were the predominant effector cells responsible for the anti-B16BL6 immunity induced by vaccination with AdRGD-gp100/mBM-DCs, and that helper function of CD4(+) T cells was necessary for sufficiently eliciting effector activity. These findings clearly revealed that highly efficient MAA gene transduction to DCs by AdRGD could greatly improve the efficacy of DC-based immunotherapy against melanoma.

Adenoviridae↗
PubMed2003

Alpha-synuclein-positive structures in association with diffuse neurofibrillary tangles with calcification.

alpha-Synuclein is known to be a major constituent of the Lewy bodies (LBs) in Parkinson's disease (PD) and the neuronal and glial cytoplasmic inclusions (NCIs, GCIs) in multiple system atrophy. alpha-Synuclein-positive inclusions such as LBs, NCIs and GCIs sometimes show colocalization with tau-positive neurofilaments. Studies using alpha-synuclein immunohistochemistry have often found LBs in the amygdala of patients with familial or sporadic Alzheimer's disease (AD), as well as in patients with Down's syndrome and AD. However, no studies have reported alpha-synuclein-positive structures in cases of diffuse neurofibrillary tangles with calcification (DNTC), which is characterized by numerous neurofibrillary tangles (NFTs) throughout the cerebral cortex but few, if any, senile plaques. We investigated the distribution of alpha-synuclein-positive structures in two cases of DNTC: a 65-year-old woman (brain weight, 850 g) and a 75-year-old woman (brain weight, 800 g). In both cases, severe cerebral atrophy predominant in the temporal lobe was noted. Microscopically, alpha-synuclein-positive intracytoplasmic inclusions and neurites were found in the superior temporal lobe (within the temporal pole), amygdala, parahippocampus, entorhinal cortex and insula, the regions most affected by the NFTs. alpha-Synuclein-positive intracytoplasmic inclusions were rare or absent in other regions of the cerebral cortex and brainstem. This distribution pattern differs from that of PD or dementia with LBs. Our findings suggest that the accumulation pattern of alpha-synuclein is a pathological feature of DNTC, and that DNTC is associated with accumulation of both tau and alpha-synuclein.

Aged↗
PubMed2003

An analysis of cervical lymph nodes metastasis in oral squamous cell carcinoma. Relationship between grade of histopathological malignancy and lymph nodes metastasis.

Cervical lymph nodes metastasis is well known to be an indicator of poor prognosis in patients with oral cancer. This study was considered 38 patients of oral squamous cell carcinoma who were treated at our department from 1993 to 1997. Histological malignancy of initial biopsy in the pretreatment period was evaluated by Anneroth's classification. The relationship of degree of histological malignancy with cervical lymph nodes metastasis were analysed in this study. Metastasis in the cervical lymph nodes was histologically confirmed in 17 out of 38 cases (44.7%). The metastasis located predominantly in the submandibular nodes and superior internal jugular nodes. According to T classification, the rate of metastasis in the cervical lymph nodes in T1 and T2 cases was around 30%, while the rate in T3 and T4 cases tended to be as high as around 60%. However, there was no significant difference. A significant relation was evident between the degree of histological malignancy and metastasis in the cervical lymph nodes (P< 0.01), indicating that the histological malignancy could be served as a predictor for metastasis in the cervical lymph nodes. Among the six parameters, a significant difference was observed only in the degree of keratinization and the mode of invasion (P< 0.05). When the sum of the degree of histological malignancy exceeds 15, metastasis in the cervical lymph nodes should be considered.

Carcinoma, Squamous Cell↗
PubMed2003

[Long-term results of atriopulmonary fontan connection for complex cardiac anomalies].

To evaluate the long-term results of atriopulmonary Fontan connection, we reviewed the outcome of 20 consecutive patients (single ventricle 8, double outlet right ventricle 8, tricuspid atresia 3, mitral atresia 1; mean age, 13 +/- 11) who underwent this operation between 1981 and 1997 at our institution. Glenn shunt preceded Fontan operation in 1 patient. Four patients had a concomitant bidirectional Glenn anastomosis at the time of the Fontan operation. Follow-up was 100% complete, and total cumulative follow-up of all patients was 241 patient-years (maximum, 20 years). Three hospital deaths and 5 late deaths were observed, resulting in 58 +/- 11% of cumulative survival at 20 years after the operation. Sudden death probably due to arrhythmias was the major cause of the late death, and occurred in 3 patients. Reoperation was required in 5 patients (2%/patient-year) at 1 to 17 years postoperatively. Re-closure of an atrioventricular valve was performed for failure of the valve closure in 3 patients at 1 to 6 years postoperatively. Reconstruction of the stenotic atriopulmonary connection (APC) was concomitantly required in 2 of the 3 patients. Pacemaker implantation was required for bradycardia with atrial fibrillation in 1 patient at 17 years. One patient with atrial flutter developed intraright atrial thrombosis at 12 years after the initial Fontan operation, and this patient underwent conversion to extracardiac conduit cavopulmonary connection with right atrial maze procedure. Atrial tachyarrhythmias are most common complications, and occurred in 12 patients (5.0%/patient-year), resulting in 40 +/- 13% of the cumulative free rate at 15 years after the operation. Thus, failure of the atrioventricular valve closure and stenosis of APC were important early to intermediate complications after the atriopulmonary Fontan connection. On the other hand, atrial tachyarrhythmias were inevitable, and were most common late complications leading to intra-right atrial thrombosis, which was successfully resolved by conversion of the conventional atriopulmonary Fontan anastomosis to extracardiac conduit cavopulmonary connection.

Adolescent↗
PubMed2003

[Ruptured bronchial artery aneurysm; report of a case].

A 74-year-old man who went into shock following an acute hemomediastinum and left hemothorax was operated on. Postoperative angiographies revealed a saccular aneurysm of the left bronchial artery of 2.0 cm in diameter. Sixty days after the initial operation, the aneurysm was resected under F-F bypass. A saccular aneurysm was found at the root of the left bronchial artery, which had a very short segment between the aneurysm and the aorta. Pathological study of aneurysm revealed thinning of the wall and lack of tunica media.

Aged↗
PubMed2003

[Emergent ascending and arch replacement for acute type A aortic dissection with anomalies of the aortic arch].

We experienced 4 cases that had to be performed emergent ascending and arch replacement for acute type A aortic dissection with anomalies of the aortic arch (aberrant right subclavian artery in 2 case and isolated left vertebral artery in 2 cases). As for the aberrant right subclavian artery, preoperative diagnosis is possible by CT scan. We must not overlook aberrant right subclavian artery in order to prevent brain complication in emergency arch replacement for acute type A aortic dissection. For the isolated left vertebral artery, incision of the aortic arch is recommended for its reconstruction.

Acute Disease↗
PubMed2002

RGD-CAP ((beta)ig-h3) is expressed in precartilage condensation and in prehypertrophic chondrocytes during cartilage development.

RGD-CAP ((beta)ig-h3), isolated from cartilage as a collagen-associated protein, was demonstrated to have a binding ability to collagen and to enhance the adhesion of chondrocytes via integrin alpha(1)beta(1). However, the role of this protein in cartilage development remains unclear. In this study, we investigated the expression of RGD-CAP ((beta)ig-h3) in chick embryos and cultured mesenchymal stem cells (MSCs) during the differentiation to chondrocytes. The effects of recombinant RGD-CAP on adhesion and DNA synthesis of MSCs and mineralization were also examined. Tissue sections from chick embryos at Hamburger-Hamilton (HH) stages 19-37 were immunostained with anti-chick RGD-CAP antibodies. The expression of RGD-CAP was slightest in chick embryos at HH stage 19, whereas a considerable expression of RGD-CAP was observed in the developing vertebrae and precartilage aggregate in the limb bud of chick embryos at HH stage 26. The expression of RGD-CAP was significantly reduced in vertebrae of chick embryo at HH stage 32. Reverse transcriptional polymerase chain reaction (RT-PCR) analysis showed that RGD-CAP was highly expressed in cultured MSCs and decreased by 4-day treatment with 10(-8) M dexamethasone when MSCs proliferated to adipocyte-like cells, whereas it was recovered by co-treatment with 3 ng/ml TGF-beta for 8-12 days when MSCs proliferated to hypertrophic chondrocyte-like cells. The adhesion and DNA synthesis of MSCs cultured on RGD-CAP-coated dishes increased significantly compared with the controls. RGD-CAP was distributed in the prehypertrophic zone in matured cartilage of the vertebrae of chick embryos at HH stage 37. Recombinant RGD-CAP inhibited the mineralization of hypertrophic chondrocytes. These results suggest that RGD-CAP ((beta)ig-h3) exerts an essential role in the early cartilage development by enhancing the adhesion and growth of the pre-chondrogenic cells, and functions as a negative regulator for mineralization at the terminal stage of the chondrogenic differentiation.

Animals↗
PubMed2002

Effects of barley yellow mosaic disease resistant gene rym1 on the infection by strains of Barley yellow mosaic virus and Barley mild mosaic virus.

Although a Chinese landrace of barley, Mokusekko 3, is completely resistant to all strains of Barley yellow mosaic virus (BaYMV) and Barley mild mosaic virus (BaMMV), and is known to have at least two resistant genes, rym1 and rym5, only rym5 has been utilized for BaYMV resistant barley breeding in Japan. In order to clarify the effect of rym1 on BaYMV and BaMMV, and to utilize the gene for resistant barley breeding, the susceptibilities of only rym1 carrying breeding lines against BaYMV and BaMMV were investigated. In the assessment of resistance to BaYMV-I, 341 F(2) populations derived from a cross between the resistant line Y4 with only rym1 and the susceptible cv Haruna Nijo shows that the segregation loosely fits a 1R:3S ratio (0.05 > P > 0.01), suggesting that the resistance is controlled by a single recessive gene, rym1. Further, none of the F(3) lines derived from the nine resistant F(2) plants showed any disease symptoms in the field infected by BaYMV-I. The same nine F(3) lines showed almost the same agronomic characters in the field infected by BaYMV-III as those in the uninfected field, apart from the symptom of showing numerous mosaics. This result indicates that the gene rym1 has an acceptable level of resistance to BaYMV-III. In the assessment of resistance to BaYMV-II, BaMMV-Ka1 and -Na1, an artificial infection method was adopted and the susceptibilities to those viruses were investigated. Although the control varieties, Ko A and Haruna Nijo, were infected with all of them, the rym1 gene carrying BC(2)F(3) lines were completely resistant to all strains. In summary, rym1 is completely resistant to BaYMV-I, -II, BaMMV-Ka1 and -Na1, and has an acceptable level of resistance to BaYMV-III. This study concludes with a discussion of the reason why the important resistance gene rym1 was eliminated along with resistant cultivars during breeding for resistance to BaYMV.

Genes, Plant↗
PubMed2002

Development of growth-associated protein-43 and neurotrophin receptor immunoreactivities in the rat urinary bladder.

Little is known about how the prenatal innervation of the urinary bladder develops. The objective of this study was to define the timing and pattern of innervation of the developing rat bladder using growth-associated protein-43 (GAP-43) immunohistochemistry. In addition, we examined the development of two different classes of transmembrane receptor proteins, the Trk family of tyrosine kinases and neurotrophin receptor p75 immunoreactivities. GAP-43-positive nerves were first detected in the bladder at embryonic day (E) 16. They were growing rapidly to the bladder dome and covered the whole bladder by E18. The density of GAP-43-containing nerves increased in the muscle layer by postnatal day (P) 0. Both Trk receptor-positive and p75 neurotrophin receptor-positive fibers were also first seen at E16. The number of Trk immunoreactive nerves reached a peak at E18, and then decreased over the following days. In contrast, p75-labeled fibers were abundant at E18-P14. There were few GAP-43 or neurotrophin receptor-positive fibers in the adult. GAP-43 immunohistochemistry provided us with a picture of innervation in the developing rat bladder. Furthermore, the demonstration of neurotrophin receptors positive fibers in the prenatal and early postnatal bladders suggests that neurotrophins may contribute to the development of the peripheral nervous system in the urinary bladder.

Animals↗
PubMed2002

Regulation of cardiac CFTR Cl(-) channel activity by a Mg(2+)-dependent protein phosphatase.

Dephosphorylation of the CFTR Cl(-) channel is known to be induced by both okadaic-acid- (OA-) sensitive and -insensitive protein phosphatases (PPs). In the present study, the effects of cytosolic free Mg(2+) on the cardiac CFTR Cl(-) current were examined in relation to the latter PP activity in guinea pig ventricular myocytes. Even when maintaining intracellular Mg-ATP at millimolar concentrations under whole-cell patch-clamp mode, cAMP-activated Cl(-) conductance was reversibly suppressed by cytosolic free Mg(2+), with an IC(50) of around 2.5 mmol/l. In contrast, changes in the cytosolic concentration of free Mg(2+) ([Mg(2+)](i)) had no effect on genistein-activated CFTR Cl(-) currents. The Mg(2+) effect on cAMP-activated CFTR Cl(-) conductance was completely reversed by application of anthracene-9-carboxylic acid (9-AC), which was previously shown to inhibit an OA-insensitive PP in cardiac myocytes. A 9-AC-sensitive fraction of endogenous PP activity in the extract of guinea pig ventricle was found to be activated by free Mg(2+) at millimolar concentrations but to be inactive at micromolar concentrations. The intracellular application of OA failed to activate basal Cl(-) conductance at millimolar [Mg(2+)](i). In the presence of OA, however, basal Cl(-) conductance became activated either by reducing [Mg(2+)](i) to micromolar concentrations or by applying 9-AC. Thus, we conclude that a Mg(2+)-dependent PP sensitive to 9-AC plays a key role in the cAMP-mediated regulation of cardiac CFTR Cl(-) channel at physiological [Mg(2+)](i)under both basal and cAMP-activated conditions. Also, it appears that the genistein-activated conformation of the cardiac CFTR channel is not sensitive to the Mg(2+)-dependent PP.

Adenosine Triphosphate↗