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Biomedical subjects

T Nakashima

Publications and source records attributed to T Nakashima.

At least 181 records · Page 10Linked to original sources
PubMed1999

MR imaging of the cochlear modiolus: area measurement in healthy subjects and in patients with a large endolymphatic duct and sac.

PURPOSE: To evaluate the cochlear modiolus with thin-section magnetic resonance (MR) imaging in healthy subjects and patients with a large endolymphatic duct and sac, and to assess whether the cochlea is normal or abnormal in patients with a large endolymphatic duct and sac. MATERIALS AND METHODS: MR images were obtained in 10 ears in five volunteers (group 1), 40 ears in 20 patients with bilateral sensory hearing loss (group 2), three ears in two patients with Mondini malformation (group 3), and 12 ears in seven patients with a large endolymphatic duct and sac (group 4). RESULTS: In groups 1 and 2, all modiolar areas were larger than 4.0 mm2. In group 3, each modiolus was smaller than 2.0 mm2. In group 4, modiolar areas were smaller than 2.0 mm2 in eight ears and were larger than 4.0 mm2 in four ears. CONCLUSION: Findings in this study confirm that a large endolymphatic duct and sac is frequently associated with modiolar deficiency, but the modiolar area is normal in some cases. This result does not support the recently proposed hypothesis that hearing loss with a large endolymphatic duct and sac is caused by the transmission of subarachnoid pressure forces into the labyrinth through a deficient modiolus.

Adolescent↗
PubMed1999

Electron microscopic and immunohistochemical investigation of Reinke's edema.

Examination was made of the vocal fold mucosa of Reinke's edema immunohistochemically and electron microscopically, with special attention to blood vessels in Reinke's space (RS). Ten surgical specimens of Reinke's edema were used, and the results obtained are summarized as follows. There were subepithelial vascularization and many dilated vessels in RS. The vessels had thin endothelium with many fenestrae, many vesicles, and a thickened basement membrane. Plasma exuded from the capillaries into surrounding tissue via fenestrae. These findings demonstrate increased permeability of the vessels. The vascular walls were thin, with few pericytes. The pericytes were situated away from the endothelial cells. Some endothelial cells and pericytes had degenerated, and vessel occlusion was apparent in some cases. These findings indicate the vessels had become fragile. Interstitial cells and/or inflammatory cells in RS showed stained cytoplasm with vascular endothelial growth factor. This growth factor may possibly enhance capillary permeability and form fragile vessels in RS. Fragility and alteration in permeability of the vessels are presumed to cause edema of RS, which may progress to Reinke's edema.

Capillaries↗
PubMed1999

Succinate dehydrogenase activities of fibers in the rat extensor digitorum longus, soleus, and cardiac muscles.

Succinate dehydrogenase (SDH) activities and cross-sectional areas (CSAs) of different types of fibers in the superficial (EDLs) and deep (EDLd) regions of the extensor digitorum longus and soleus (SOL) muscles and the left ventricular muscle of the heart (HEART) of 10-week-old male rats were determined using quantitative histochemistry and a computer-assisted image processing system. The fibers were classified as type I, type IIA, type IIB, or type IIC according to their histochemically assessed adenosine triphosphatase activities. The mean SDH activity was higher and the mean CSA was smaller in type IIA fibers than in type IIB fibers in both the EDLs and EDLd. The mean SDH activity of type IIA fibers in the SOL was higher than that of type I fibers. Fibers in the HEART showed the highest mean SDH activity and the smallest mean CSA among all fiber types in the muscles examined. There was an inverse correlation between CSA and SDH activity for the different fiber types in different muscles. These data suggest that the SDH activity of fibers in muscle is fiber type- and size-specific, and that the highest SDH activity of fibers in the left ventricular muscle of the heart contributes to their functional properties, i.e., high fatigue resistance.

Animals↗
PubMed1999

Size of lipid microdroplets effects results of hepatic arterial chemotherapy with an anticancer agent in water-in-oil-in-water emulsion to hepatocellular carcinoma.

We have initially prepared a new drug delivery system for hepatocellular carcinoma (HCC). Using sonication and a detergent, iodinated poppy seed oil (IPSO) can be mixed with an aqueous solution of epirubicin to make a water-in-oil emulsion. The water-in-oil emulsion is further passed through a microporous glass membrane and split into saline to make a long-term inseparable water-in-oil-in-water emulsion (W/O/W) that consists of IPSO microdroplets. To investigate the effect of the size of IPSO microdroplets on the efficacy of injection chemotherapy with W/O/W in patients with HCC, 32 HCC patients were randomly assigned and treated with W/O/W of small IPSO microdroplets (30 micrometers in diameter) containing 60 mg of epirubicin (n = 16, group A) or W/O/W of large IPSO microdroplets (70 micrometers) containing the same amounts of epirubicin (n = 16, group B). Effects were assessed by measuring the percentage of decline of the alpha-fetoprotein (AFP) level in a week from the AFP level immediately before the treatment. The decline was significantly larger in group B (50.5 +/- 19.8, mean +/- S.D.) compared with group A (18.9 +/- 33.1; p <.005). The size of IPSO microdroplets injected into the hepatic artery determines the decrease of serum AFP levels of the patients with HCC.

Alanine Transaminase↗
PubMed1999

The alteration of penicillin-binding proteins (PBPs) in drug-resistant Streptococcus pneumoniae isolated from acute otitis media.

Streptococcus pneumoniae is the micro-organism most frequently isolated from acute otitis media (AOM). Recently, drug-resistant or insensitive strains have been prevalent among pneumococcal AOM cases and were reportedly associated with persistent or recurrent otitis media. The purpose of this study was to examine the alterations of penicillin-binding proteins (PBPs) in Streptococcus pneumoniae isolated from AOM. The PBP samples from 21 clinically isolated strains were examined by 14C-penicillin binding assay and also by adding CCL and CDTR as competitors of 14C-penicillin. Reduced signals in PBP1A and PBP2X/2A were typically observed with the penicillin-resistant Streptococcus pneumoniae samples, while widely different PBP profiles were obtained in each strain of penicillin-insensitive Streptococcus pneumoniae. The competitive binding assay with penicillin-insensitive strains revealed the reduced affinity of CCL to PBPs in comparison with that of CDTR. The results of the penicillin-binding assay were consistent with the results from minimal inhibitory concentration analysis, and its potential usefulness for the prediction of drug resistance was demonstrated.

Acute Disease↗
PubMed1999

Autoregulation of cochlear blood flow.

We reviewed papers written about autoregulation of cochlear blood flow (CBF). In animals, autoregulation of CBF has been recognized not only by variations of systemic blood pressure (BP) but also by manipulations to the blood vessels, such as occlusion of the anterior inferior cerebellar artery, occlusion of the draining veins from the cochlea, and variations of the inner ear pressure. Recent reports have shown that autoregulation of CBF is not so different from that of cerebral blood flow in its strength, but it is disturbed in endolymphatic hydrops or aged animals. Since it became possible to measure CBF in humans, clinical investigation about autoregulation of CBF needs to be done in various inner ear diseases.

Animals↗
PubMed1999

Proton magnetic resonance assay of total and taurine-conjugated bile acids in bile.

Biliary bile acids, coexisting with phospholipid and cholesterol, are partly conjugated with taurine. In the present report we show that total and taurine-conjugated bile acids in bile can be simultaneously and quantitatively measured by high-resolution (1)H-nuclear magnetic resonance ((1)H-NMR) spectroscopy. We used a 7.05-Tesla NMR spectrometer to obtain the (1)H-NMR spectra of model and biological biles. Only addition of trimethylsilyl-3-propionic acid sodium salt-D(4) (TSP) to each sample as an internal standard was required in preparation for (1)H-NMR measurement. In (1)H-NMR spectra of rat bile, peaks of C-18 methyl protons of bile acids and of C-25 methylene protons on the taurine moiety of taurine-conjugated bile acids were detected at 0.7 ppm and 3.1 ppm, respectively. Peak areas, of C-18 and C-25 peaks, increased in proportion to the concentrations of bile acids or taurine-conjugated bile acids, even in the presence of phospholipid and cholesterol. The accuracy of NMR measurement of total and taurine-conjugated bile acids was confirmed by comparing the results of NMR with those of enzyme-fluorimetry. The results clearly demonstrate that (1)H-NMR spectroscopy can be applied to the quantitative determination of total and taurine-conjugated bile acids in bile without troublesome preparative steps.

Animals↗
PubMed1999

[Treatment of solid tumor by a direct electric current].

This is a case report of a 37-year-old Japanese married female with laryngeal sarcoma, treated by direct electric current so as to obtain remission for more than 4 years without signs of recurrence. Due to her hoarseness and laryngeal numb feeling she underwent a laryngeal examination including a biopsy, resulting in a diagnosis of sarcoma. She refused a total laryngectomy and was given Cobalt treatment of 40 Grey. In the following several months, no improvement was observed, objectively or subjectively. In Nagoya University Hospital the patient then received direct electric current therapy of 36 Coulombs through two platinum electrodes inserted into the tumor under a CT guide, pericutaneously. Two months later, as the hoarseness remained in spite of some improvement, she underwent another session of direct electric current therapy of 14.4 Coulombs through the platinum electrodes by bronchoscope-guided direct insertion. Her hoarseness soon disappeared thereafter and there was a regression of the tumor in 6 months. She did well thereafter without any signs of recurrence for 4 years. Clinical treatment of solid tumors with electric treatment with direct electric current has been done in more than 8,000 cases with CR in 25% of all cases and PR in 50%. Its mechanism, however, remains unclear. In our experimental animal studies, apoptosis was observed. It is considered that this electric therapy using direct electric current will be recognized as one method to treat solid tumors.

Adult↗
PubMed1998

Micellization of Mixed System of Bile Salt and Nonionic Surfactant: Sodium Deoxycholate and Decanoyl-N-methylglucamide.

Micelle formation was studied for mixed surfactant systems of a nonionic surfactant, nonanoyl-N-methylglucamine (MEGA-10) with a bile salt, sodium deoxycholate (NaDC), in water at 30 degreesC. NaDC and MEGA-10 are quite different from each other in terms not only of hydrophobic but also of hydrophilic groups. Surface tension of the aqueous solution (gamma) at different mixing ratios was measured by the drop volume method, and critical micellization concentrations (CMCs) were determined from the gamma vs CMC curves at discrete mole fractions of MEGA-10 (XMEGA) in the surfactant mixture. The CMC-XMEGA curve showed a positive deviation from ideal mixing. The apparent interaction parameter (WR) upon micelle formation was evaluated by applying the Rubingh equations derived on the basis of the regular solution theory. The different theory developed by Motomura et al. has been also applied. The analysis of CMC data indicated that the properties of mixed micelles are different between the ranges below and above XMEGA congruent with 0.2 where an azeotrope exists and that the composition of mixed micelles is very similar to that of monomeric species in bulk solution. Copyright 1998 Academic Press.

Journal Article↗
PubMed1998

Crystallization and preliminary X-ray crystallographic study of a 23S rRNA binding domain of the ribosomal protein L2 from Bacillus stearothermophilus.

Ribosomal protein L2 from Bacillus stearothermophilus, a single polypeptide chain with 275 amino acid residues, is a primary 23S rRNA-binding protein in the large ribosomal subunit. Crystals of a 23S rRNA binding domain (BstL2-RBD: positions 60-201) of the ribosomal protein L2 from B. stearothermophilus overexpressed in Escherichia coli have been grown in 0.1 M MES (pH 6.5) containing 15% polyethylene glycol 20 000. The crystals diffract to 2.3-A resolution on a synchrotron X-ray source. The crystal belongs to the space group P1 and the unit cell axes are a = 28.05, b = 36.20, c = 69.74 A, alpha = 99.58 degrees, beta = 95.86 degrees, and gamma = 102.62 degrees. There are two molecules of the BstL2-RBD in the asymmetric unit.

Bacterial Proteins↗
PubMed1998

Arteriovenous malformation in association with moyamoya disease. Report of two cases.

The authors report two rare cases of arteriovenous malformation (AVM) associated with moyamoya disease. An AVM, supplied by transdural communicating arteries, was located in the right occipital lobe in one patient who presented with ischemia. The second AVM, which was supplied by basal moyamoya vessels, was located in the posterior part of the left frontal lobe in a patient who developed intracerebral hemorrhage that occupied the left basal ganglion. A review of the literature revealed a total of 12 AVMs in 11 patients with moyamoya disease including our cases. All AVMs were cerebral and two were supplied by normal cerebral arteries, whereas six AVMs were supplied by basal moyamoya vessels at the base of the brain and four AVMs were supplied by external carotid arteries through the transdural communicating arteries. Every AVM drained into deep or cortical cerebral veins. These findings suggest that the hyperangiogenic character of moyamoya disease occasionally induces the development of acquired arteriovenous shunts that mimic AVM.

Journal Article↗
PubMed1998

1H-NMR investigation of the influence of the heme orientation on functional properties of myoglobin.

There are two interconverting forms of myoglobin, which differ in the orientation of the heme by a 180 degrees rotation around the alpha,gamma-meso axis; the proteins possessing the same heme orientation, as found in the single crystal, and the reversed heme orientation are called the major and minor forms, respectively. Structures and functional properties of these two forms have been investigated by NMR. Heme peripheral side-chain and non-coordinated amino acid proton resonances of the minor form in its met-cyano form have been assigned and the comparison of the shift between the corresponding resonances of the two forms revealed that the heme electronic structure is not largely influenced by the heme rotation. On the other hand, the exchange rate of His E7 NepsilonH proton of the minor form is larger by a factor of 3-5 than that of the major one, indicating that the stability of the hydrogen bond between Fe-bound ligand and His E7 is slightly weaker in the minor form that in the major one. The rate of autoxidation of oxy-myoglobin and azide affinity of met-aquo myoglobin were also found to depend on the orientation of the heme.

Animals↗
PubMed1998

Cyclooxygenase 2 expression by endothelin-1-stimulated mouse resident peritoneal macrophages in vitro.

Macrophages have been shown to produce endothelin and to play a role in the pathogenesis of neural damage after cerebral ischemia or vasospasm after subarachnoid hemorrhage. Cyclooxygenase 2 is induced during inflammation following brain insult and participates in inflammation-mediated neurotoxicity. However, it has not yet been established how endothelin-1 acts on cyclooxygenase 2 expression in macrophages. In the present study, we examined the effects of endothelin-1 on cyclooxygenase 2 expression and prostaglandin E2 production, and the effects of endothelin ET(A) and ET(B) receptor antagonists. Stimulation by endothelin-1 ranging from 10(-11) to 10(-9) M time and dose dependently increased the production of prostaglandin E2 and the expression of cyclooxygenase 2 protein without changing that of cyclooxygenase 1 protein, an effect which was inhibited by dexamethasone, nonsteroidal anti-inflammatory drugs and the selective endothelin ET(B) receptor antagonist, BQ788 (N-cis-2,6-dimethylpiperidinocarbonyl-L-gamma-methyl-leucyl-D-L-me thoxycarbonyl-tryptophanyl-D-norleucine). The selective endothelin ET(A) receptor antagonist, BQ123 [cyclo (D-Trp-D-Asp-Pro-D-Val-Leu)] also inhibited these reactions, but its potency was less than that of the selective endothelin ET(B) receptor antagonist. Endothelin ET(A) and ET(B) receptor antagonists had no effects on cyclooxygenase 2 protein expression and prostaglandin E2 production in lipopolysaccharide-stimulated macrophages. We conclude that endothelin-1 increases cyclooxygenase 2 protein expression and prostaglandin E2 production via mainly endothelin ET(B) receptors and partly endothelin ET(A) receptors in macrophages; however, lipopolysaccharide increases both cyclooxygenase 2 protein expression and prostaglandin E2 production in pacrophages without involving endothelin ET(A) or ET(B) receptor-mediated processes.

Animals↗
PubMed1998

Increased Fas-mediated cytotoxicity of CD4-positive T cells in patients with human T-lymphotropic virus type I-associated myelopathy.

Using a 51Cr release assay, we investigated Fas-mediated cytotoxicity of peripheral blood CD4+ T cells of patients with human T-lymphotropic virus type-I (HTLV-I)-associated myelopathy (HAM) against T98G, a glioblastoma cell line which expresses Fas. Cytotoxic activity of CD4+ T cells against T98G was significantly higher in HAM patients than in controls. Moreover, when CD4+ T cells of HAM patients were preincubated with a monoclonal antibody to human Fas ligand (FasL), cytotoxic activity against T98G was significantly suppressed. These results suggest that damage to nervous tissues by the Fas/FasL system is involved in the pathogenesis of HAM.

Aged↗
PubMed1998

Insulin-like growth factor I stimulates proliferation and Fas-mediated apoptosis of human osteoblasts.

In vitro studies have shown that insulin-like growth factor I (IGF-I) is a potent growth factor for osteoblasts, although both bone formation and resorption are upregulated by IGF-I in vivo. To understand the difference in the action of IGF-I observed in vitro and in vivo experiments, we examined the effect of IGF-I on the proliferation and Fas-mediated apoptosis of human osteoblasts in vitro. Human osteoblastic cell line MG63 and human primary osteoblast-like cells obtained from biopsy specimens were used as human osteoblasts. Cells were cultured with or without various concentrations of IGF-I followed by determination of the proliferative response and Fas-mediated apoptosis. IGF-I dose dependently stimulated the proliferation of cultured human osteoblasts. Both Fas expression and the degree of anti-Fas IgM-induced apoptosis of human osteoblasts was also augmented by IGF-I. Furthermore, the cytotoxicity of Fas ligand (FasL) cDNA transformants against human osteoblasts was increased when IGF-I-stimulated osteoblasts were used as target cells, indicating that stimulation of IGF-I increased functional Fas expression on human osteoblasts as well as their proliferation. The addition of DEVD-CHO, a specific inhibitor of CPP32, to the culture resulted in a significant inhibition of Fas-mediated apoptosis of both unstimulated and IGF-I-stimulated osteoblasts, although it did not affect the proliferative response or Fas expression. Our data suggest that activation of CPP32 is necessary for Fas-mediated apoptosis of human osteoblasts, and treatment of IGF-I increased this signaling pathway. In contrast, regulation of proliferation and Fas expression of the cells were probably not affected by CPP32 activation. Our results suggest that IGF-I acts on cultured human osteoblasts by increasing their proliferation and induction of Fas-mediated apoptosis by neighbouring FasL+ cells such as osteoclasts, thus probably functioning as a local coupling factor in the bone in vivo, stimulating both bone formation and resorption.

Apoptosis↗