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Biomedical subjects

T Okuda

Publications and source records attributed to T Okuda.

At least 127 records · Page 7Linked to original sources

The Microwave Spectrum of n-Butyraldehyde Oxime.

The microwave spectrum of n-butyraldehyde oxime was observed in the frequency region 26.5-40 GHz. Four rotational conformers were found to exist in the gas phase; among these, two conformers belonged to the (E)-geometrical isomer and the other two to the (Z)-geometrical isomer. The microwave spectrum attributed to one of these two rotational conformers of (E)-butyraldehyde oxime was analyzed, and its rotational constants for the ground vibrational state were determined: A = 15883(379), B = 1269.97(1), C = 1251.60(1) MHz. The conformational structure of the molecule is discussed, referring to the rotational constants obtained and the ab initio molecular orbital calculation. Copyright 1998 Academic Press.

Journal Article↗

Virtual MRI endoscopy of the intracranial cerebrospinal fluid spaces.

We used constructive interference in steady state (CISS) 3D Fourier transform (3DFT) MRI data sets to obtain three-dimensional (3D) virtual MRI endoscopic views of the intracranial cerebrospinal fluid (CSF) spaces, processing them with a commercially available perspective endoscopic algorithm. We investigated the potential of the intracranial virtual MRI endoscopy applied to visualisation of the pathology in 13 patients with surgically confirmed trigeminal neuralgia (3), hemifacial spasm (3), acoustic neuroma (3), suprasellar germinoma (1), Langerhans cell histiocytosis (1), lateral ventricle nodules (1) and pituitary dwarfism (1). All images were acquired using a 1.5-T imager employing a circular polarised head coil. The CISS-3DFT data sets were transferred to a workstation for processing with the perspective endoscopic algorithm. Postprocessing for virtual MRI endoscopy was possible for all data sets. The lesions in 12 patients, and their complex anatomical relationships with the surrounding structures, were well seen on the 3D images. A small acoustic neuroma in the internal auditory meatus was not seen using virtual endoscopy. Although virtual MRI endoscopy has limitations, it provides 3D images which cannot be acquired using any other procedure.

Adolescent↗

Dinocampus (=Perilitus) coccinellae teratocyte-specific polypeptide: its accumulative property, localization and characterization.

Dinocampus (=Perilitus) coccinellae (Braconidae: Hymenoptera) teratocytes synthesize a teratocyte-specific polypeptide (TSP) with a high molecular weight of 540kDa. The TSP has a tendency to accumulate in the teratocyte cells without release after synthesis ([Okuda and Kadono-Okuda, 1995]), which was confirmed in this study. Pulse-chase fluorography indicated that teratocytes at a younger stage (6 days after parasitization)secreted negligible TSP into the medium after synthesis, while teratocytes at an older stage (11 days after parasitization)secreted the synthesized products into the medium, although the amount released was still low. Western blot with anti-TSP serum showed that only a small amount of TSP appeared in the parasitized host hemolymph, even when TSP synthesis by teratocytes was actively taking place, which also supported the accumulative nature of TSP. The immunoelectronmicroscopic studies revealed that the TSP was localized specifically in high electron-dense vacuoles. Lectin blot analysis identified TSP as a high mannose glycoprotein. The amino acid composition of the major subunit of the TSP was quite similar to that of nutritive proteins such as vitellogenin and storage proteins of some insects. These characterization data, together with the accumulation property of the TSP indicates that Dinocampus teratocyte primarily plays a nutritive role for the developing parasitoid larvae. TSP exhibited esterase activity, which indicates that TSP may have an additional function in the host-parasitoid reaction.

Journal Article↗

Anti-latent TGF-beta binding protein-1 antibody or synthetic oligopeptides inhibit extracellular matrix expression induced by stretch in cultured rat mesangial cells.

Transforming growth factor-beta (TGF-beta) is usually secreted as a large latent complex associated with latent TGF-beta binding protein-1 (LTBP-1), which is known to bind to extracellular matrix (ECM) components. Although the LTBP-ECM interaction has been suggested to play a role in the activation and biological action of TGF-beta, the precise mechanism is still unclear. In glomerular hypertension mesangial cells are believed to perceive the increased cyclic strain and we have recently reported that cyclic mechanical stretch in vitro enhances the expression of ECM components via an autocrine/paracrine secretion of TGF-beta in cultured rat mesangial cells. Therefore, in this study we examined the role of LTBP-1 in the stretch-induced, TGF-beta-mediated ECM expression. Mesangial cells expressed mRNA for short and long forms of LTBP-1 (LTBP-1S and LTBP-1L, respectively). Mesangial cells were subjected to cyclic stretch to provide a maximal elongation of 20% at a rate of 60 cycles/min for 24 to 36 hours in the presence of polyclonal antibody raised against human LTBP-1 or synthetic oligopeptides corresponding to the N-terminal portions of human LTBP-1, which may work as competitive inhibitors against the LTBP-ECM association. Both anti-LTBP-1 antibody (Ab39) and synthetic oligopeptides inhibited the stretch-induced mRNA expression of type I collagen and fibronectin in a dose-dependent manner, but the inhibition by Ab39 or the oligopeptides was recovered by adding recombinant TGF-beta. Ab39 or the oligopeptides did not change the effect of exogenously added TGF-beta, such as growth-inhibition in mink lung epithelial cells. These results suggest that mesangial cells secrete TGF-beta as a large latent complex, and the LTBP-ECM interaction may be a pivotal step in TGF-beta action and ECM accumulation, providing a new therapeutic strategy against progression of glomerulosclerosis and other fibrotic diseases.

Amino Acid Sequence↗

Rotation plasty for osteosarcoma of the femur.

A 20-year-old female with right femoral osteosarcoma noted severe pain and swelling of the right thigh, and was transferred to the authors' hospital after suffering a pathologic fracture of the right femur. Plain x-ray disclosed a tumor shadow extending from the pathologic fracture of the distal portion of the femur to the center of the diaphysis. MRIs showed a broad lesion and hematoma, and invasion to the femoral vascular bundle was suspected. Angiograms revealed vascularization coincidental to the tumor, and an irregular vascular wall of the femoral artery, which was shifted posteriorly. After consultation with the patient and her family, rotation plasty was performed. The sciatic nerve was isolated and preserved; major vessels were sectioned proximally and distally because of tumor tissue invasion to the femoral artery and vein. After wide excision of the tumor, the leg was rotated outward 180 degrees, and osteosynthesis was performed between the remaining femur and the tibia, followed by microsurgical anastomosis of vessels. Five years postoperatively, no local recurrence or metastasis has been observed. The patient has excellent functional recovery without pain, and no other complications.

Adult↗

Use of fluid-attenuated inversion recovery (FLAIR) pulse sequences in perinatal hypoxic-ischaemic encephalopathy.

The purpose of this study was to evaluate the usefulness of fluid-attenuated inversion recovery (FLAIR) techniques in patients with perinatal hypoxic-ischaemic encephalopathy. 13 patients with a history of perinatal hypoxic-ischaemic encephalopathy (age range 1 month to 3.6 years) underwent T1 and T2 weighted spin echo and FLAIR imaging with a 1.5 T superconducting unit. FLAIR images were qualitatively evaluated in comparison with T1 and T2 weighted images by three experienced radiologists. Quantitative analysis (contrast and contrast-to-noise ratio) was also performed. FLAIR images were preferred to T1 and T2 weighted images in the demonstration of periventricular leukomalacia (PVL), cystic PVL and subcortical lesions near the brain surface. On T1 and T2 weighted images, almost all lesions were demonstrated as hypointense or hyperintense areas, respectively. However, FLAIR images could differentiate cystic lesions by their signal intensities. FLAIR images were not diagnostic in two cases with PVL. In conclusion FLAIR sequences provide useful information in patients with perinatal hypoxic-ischaemic encephalopathy.

Child, Preschool↗

CT angiography in vascular intervention for steno-occlusive diseases: role of multiplanar reconstruction and source images.

The aim of this study was to assess the efficacy of CT angiography for steno-occlusive diseases before and after interventional procedures, focusing on the role of multiplanar reconstruction (MPR) and source images. 17 patients with 20 steno-occlusive lesions underwent CT angiography before and after interventional procedures. For each lesion, the percentage stenosis obtained on CT angiography was compared with that on conventional angiography. In addition, MPR and source images were evaluated for the presence of wall thickening and calcification before interventional procedures, and the presence of dissection and luminal shape after interventional procedures. These findings were compared with those of conventional angiography. Although the percentage stenosis depicted on CT angiography correlated well with that on conventional angiography, MPR and source images clearly demonstrated the effect of intervention and the residual stenosis. MPR and source images clearly depicted wall thickening, wall calcification, the presence of dissection and the luminal shape. CT angiography provides useful information before intervention, while MPR and source images are of value in evaluating arterial wall abnormalities and morphological changes associated with interventional procedures.

Adult↗

The effects of static magnetic fields and X-rays on instability of microsatellite repetitive sequences.

To determine the genetic effect of static magnetic fields (SMF), which are not supposed to produce any significant DNA damage, we took advantage of DNA mismatch repair (MMR) deficient cells, in which all the errors produced during DNA replication are left uncorrected. We first established a simple and less labor-intensive method to analyze genetic changes in microsatellite repetitive sequences in the MMR-deficient cells. After exposure to a strong SMF (6.34T) for 24 h, both MMR deficient HCT116 cells and proficient HeLa S3 cells did not exhibit any significant effect on microsatellite changes. Moreover, when HCT116 cells were synchronized at the G1/S boundary by aphidicolin and exposed to SMF during the whole S-phase, no increase in microsatellite changes was either observed. In contrast, irradiation by a low dose X-ray (2Gy) significantly increased microsatellite changes in HCT116 cells. This suggested that exposure to strong SMF may not induce any significant level of genetic changes in microsatellite sequences.

Cell Line↗

Genetic and non-genetic basis of essential hypertension: maladaptation of human civilization to high salt intake.

The relation between salt intake and hypertension has long been controversial. Available evidence provides conflicting results. However, biological and evolutionary insights into the structure and principle function of the kidney and the blood pressure sustaining machinery, with the extracellular fluid volume and the renin-angiotensin system acting as a central player, clearly indicate that salt has been a precious commodity in the terrestrial animal kingdom and that essential hypertension may be a consequence of the kidney's maladaptation to excess salt intake, which is specific to recent human civilization. This review provides a hypothesis to explain how and why hypertension develops and attempts to define the roles of genetic, non-genetic, and environmental factors in its pathogenesis.

Adaptation, Physiological↗

Correlation of MR imaging-determined cerebral blood volume maps with histologic and angiographic determination of vascularity of gliomas.

OBJECTIVE: Our purpose was to evaluate the relationships between the ratio of maximum relative cerebral blood volume (rCBV) (rCBV ratio = rCBV[tumor]/rCBV[contralateral white matter]) and histologic and angiographic vascularities of gliomas using the gradient-echo echoplanar MR imaging technique. We also evaluated the usefulness of rCBV maps for grading gliomas. SUBJECTS AND METHODS: We examined 30 patients with histologically verified gliomas. Gliomas were classified as glioblastoma, anaplastic glioma with enhancement, anaplastic glioma without enhancement, and low-grade glioma. The maximum rCBV ratio of each glioma was compared with both histologic and angiographic vascularities, and the relationship between the maximum rCBV ratios and each type of glioma was established. RESULTS: The maximum rCBV ratios of the gliomas significantly correlated with both histologic and angiographic vascularities (p < .001). Mean values and SDs of maximum rCBV ratios of each type of tumor were 7.32+/-4.39 for glioblastomas, 5.84+/-1.82 for anaplastic gliomas with enhancement, 1.53+/-0.75 for anaplastic gliomas without enhancement, and 1.26+/-0.55 for low-grade gliomas. The maximum rCBV ratios of the glioblastomas were significantly higher than those of the anaplastic gliomas without enhancement (p = .002) and the low-grade gliomas (p < .001). The maximum rCBV ratios of the anaplastic gliomas with enhancement were higher than those of the anaplastic gliomas without enhancement and the low-grade gliomas, but the differences were not statistically significant (p = .08 and p = .03, respectively). CONCLUSION: The results of perfusion-sensitive MR imaging with gradient-echo echoplanar technique correlated with both histologic and angiographic vascularities.

Adolescent↗

TMC-52A to D, novel cysteine proteinase inhibitors, produced by Gliocladium sp.

New cysteine proteinase inhibitors, TMC-52A, B, C, and D, were isolated from the fungal fermentation broth. On the basis of a taxonomical study, the producing strain, F-2665, was characterized as Gliocladium sp. Spectroscopic analyses and chemical degradation have shown TMC-52A to D to be epoxysuccinyl peptides. TMC-52A to D strongly inhibited cysteine proteinases, in particular, cathepsin L with IC50 values of 13 nM, 10nM, 10nM, and 6nM, respectively.

Cathepsin L↗

[Successful treatment of hepatic metastasis of gastric cancer with 5'-DFUR and Lentinan].

Satisfactory therapeutic effects are rarely obtained with oral chemotherapy for gastric cancer. We have experienced successful treatment for synchronous hepatic metastasis of gastric cancer with 5'-DFUR and Lentinan. The patient was a 78-year-old female, diagnosed as having gastric cancer with multiple hepatic metastases, who underwent gastrectomy. Immunohistochemistry of the resected specimens with anti-thymidine phosphorylase (dThdPase) antibody yielded positive results for dThdPase in the primary tumor as well as the hepatic metastases. Two months after surgery, administration of 400 mg of 5'-DFUR per day and 2 mg i.v. of Lentinan every other week was started. Four months after discharge, carcinoembryonic antigen (CEA) in plasma showed an abrupt logarithmic decline. Furthermore, a 99% reduction in hepatic metastases was demonstrated by abdominal CT. At present, 22 months after surgery, the patient is managed on an outpatient basis with no complaints of any side effects. Immunochemotherapy using 5'-DFUR and Lentinan may be effective against gastric malignancies expressing dThdPase activity.

Adenocarcinoma↗

[Anesthetic management of a patient with dilated cardiomyopathy using olprinone].

A 51-year-old man with dilated cardiomyopathy, who had been treated with medication for five years, was scheduled for abdomioperineal resection of the rectum. Preoperative echocardiography demonstrated left ventricular dilation and hypertrophy, with an ejection fraction of 0.34. Anesthesia was induced with ketamine 40 mg and fentanyl 0.5 mg intravenously. Endotracheal intubation was facilitated by administration of vecuronium 10 mg. Anesthesia was maintained with nitrous oxide-oxygen-sevoflurane and fentanyl. In order to regulate myocardial contractility and after-load, use of a phosphodiesterase III inhibitor was considered, although phosphodiesterase III inhibitors are known to induce arrhythmias, which should be avoided in dilated cardiomyopathy patients. We chose olprinone, because its inotropic action is not associated with arrhythmogenecity. Before infusing olprinone, cardiac output was 4.5 l.min-1 and systemic vascular resistance was 1306 dynes.sec.cm-5. When olprinone was continuously infused for one hour, cardiac output increased to 5.2 l.min-1 and systemic vascular resistance decreased to 958 dynes.sec.cm-5. Some premature ventricular contractions occurred, but they were easily controlled by administration of 50 mg lidocaine. These clinical data demonstrate that olprinone enhanced myocardial contractility, and decreased after-load and arrhythmogenecity in a dilated cardiomyopathy patients. In conclusion, olprinone is useful in the perioperative cardiovascular management of surgical patients with dilated cardiomyopathy.

Anesthesia↗

MR of denervated tongue: temporal changes after radical neck dissection.

PURPOSE: The purpose of this study was to evaluate the temporal changes of MR imaging in the denervated tongue after a radical neck dissection. METHODS: One hundred seventy-four consecutive MR studies in 116 patients with radical neck dissections for malignant tumors of the head and neck were evaluated retrospectively. Patients with tumors involving the tongue or hypoglossal nerve were not included in this study. RESULTS: Abnormal signal intensity and/or hemiatrophy on the side of the tongue operated on was seen in 22 patients who had hypoglossal paralysis after radical neck dissection. The denervated side of the tongue appeared hypointense to hyperintense relative to the normal side on T1-weighted images and hyperintense on T2-weighted images. Signal intensity ratios of the abnormal to normal muscles were 0.9-1.6 on T1-weighted images and 1.3-2.8 on T2-weighted images. High signal intensity on T1-weighted images appeared 5 months or more after the dissection, whereas on T2-weighted images, the most prominent increases in signal intensity appeared in the first several months after denervation. Hemiatrophy of the tongue was observed on MR images obtained more than 6 months after surgery. CONCLUSION: MR findings in the denervated tongue are compatible with histologic changes and are characterized by an enlarged extracellular fluid space or fatty infiltration. The pattern of signal intensity and the degree of hemiatrophy suggest the duration of denervation.

Adult↗

[Pretreatment with magnesium sulphate enhances vecuronium-induced neuromuscular block].

The interaction between magnesium sulphate (MgSO4) and vecuronium was investigated during isoflurane-nitrous oxide-oxygen anesthesia. Neuromuscular function was evaluated by recording the single twitch of the abductor policis muscle. Anesthesia was induced with thiamylal followed by injection of vecuronium. The effects of pretreatment with MgSO4 (20 or 40 mg.kg-1) on the potency of vecuronium were compared with observations in patients without MgSO4 pretreatment (control). We also examined the serum concentration of magnesium ions after administration of MgSO4. We found that the neuromuscular effect of vecuronium was not influenced by pretreatment with MgSO4 20 mg. On the contrary, the onset time of vecuronium was decreased and the duration of action until 25% recovery was increased by pretreatment with MgSO4 40 mg. The serum concentration of magnesium ions after administration of MgSO4 40 mg was significantly higher than that after 20 mg. We conclude that pretreatment with MgSO4 40 mg but not 20 mg enhances vecuronium-induced neuromuscular block.

Adult↗

[Evaluation of peritoneal lavage smears and intraperitoneal administration of anti-neoplastic agents in stage III and IV gastric cancer].

Examinations of peritoneal lavage smears (cy) in gastric cancer surgical stages III and IV are very important for determining the disease stage. We have been carrying out these examinations for 8 years. One hundred sixty patients with gastric cancer were examined. The incidence of cy positivity was higher in T4 than in T3, and higher in P1,2,3 than in P0. We performed intraperitoneal administration of CDDP in 10 patients with gastric cancer using a reservoir (Infuse-A-Port) implanted in the abdominal wall once a week. No difference in survival was observed between patients who received chemotherapy via i.p. and those who received it i.v.

Adenocarcinoma↗

An allatostatic factor and juvenile hormone synthesis by corpora allata in Locusta migratoria.

The hemolymph juvenile hormone (JH) titer in sexually immature female adults of Locusta migratoria (Ibaraki strain, Japan) was lower than in sexually mature females; nevertheless, JH synthetic activity by the corpora allata (CA) in vitro was considerably higher in immature females than in sexually mature females ([Okuda et al., 1996]). We carried out experiments to explain this contradiction. The CA activity of sexually immature female adults was very low when the CA were incubated as a complex together with the corpora cardiaca (CC) and brain. When the same complex was assayed after cutting the nerve cord connecting the CC and CA (NCA1), JH synthesis by the CA was enhanced tenfold. When this pair of CA was incubated in fresh medium without the CC and brain, JH synthesis was further increased. Therefore, the higher in-vitro JH production by CA from immature female adults was the result of isolation of the CA from the brain and CC. A methanolic extract of brain-CC complexes contained a factor that inhibited JH synthetic activity by CA in vitro in both immature and mature insects, and this inhibition was reversible. The factor was heat-resistant but lost allatostatic activity after pronase digestion. These results indicate that the allatostatic factor is probably a heat-stable peptide.

Journal Article↗

Cloning, functional expression and tissue distribution of rabbit alpha1a-adrenoceptor.

A cDNA clone, which has an open reading frame of 1398 nucleotides encoding a 466-amino-acid peptide, has been isolated from rabbit liver cDNA library. Compared with the peptide sequence, it shows high homology to alpha1a adrenoceptors of human, bovine and rat. We expressed this clone in COS-7 and investigated the pharmacological properties, revealing similarity to those of human alpha1a adrenoceptors. Competitive RT/PCR has detected the mRNA in variety of rabbit tissues, especially abundantly in liver, vas deferens, brain, and aorta, but not in heart.

Amino Acid Sequence↗