Search PubMed⌕ Search

Biomedical subjects

T Oshima

Publications and source records attributed to T Oshima.

At least 127 records · Page 7Linked to original sources
PubMed1999

Endoscopic endonasal repair of orbital floor fracture.

BACKGROUND: High-resolution endoscopes and the advent of endoscopic instruments for sinus surgery provide surgeons with excellent endonasal visualization and access to the orbital walls. OBJECTIVE: To demonstrate repair of orbital floor blowout fractures through an intranasal endoscopic approach that allows repair of the orbital floor fracture and elevation of the orbital content using a balloon catheter without an external incision. DESIGN: This study was a retrospective analysis of 11 patients who underwent surgical repair of orbital floor fractures from September 1994 to June 1997. There were 10 male patients and 1 female patient, aged 12 to 32 years (mean age, 24 years). These patients had undergone primary repair of pure orbital blowout fractures and were followed up at least 6 months after surgery. RESULTS: There were no intraoperative or postoperative complications. Nine patients showed a complete improvement of their diplopia. Two patients with posterior fractures showed persistent diplopia, which was well managed by prisms. CONCLUSION: Endoscopic repair of the orbital floor blowout fracture using an endonasal approach appears to be a safe and effective technique for the treatment of diplopia.

Adolescent↗
PubMed1999

Intracellular mechanisms of hydrogen peroxide-mediated neutrophil adherence to cultured human endothelial cells.

We examined which endothelial second messengers are involved in peroxide-mediated endothelial-neutrophil adhesion with respect to endothelial P-selectin expression and platelet-activating factor (PAF). Peroxide (0.5 mM)-mediated adhesion was blocked by a protein kinase C (PKC) inhibitor, Gö6976 (10 nM); an intracellular calcium chelator, TMB-8 (0.1 mM); and a protein kinase G (PKG) inhibitor, KT5823 (0.5 microM); but not by a tyrosine kinase inhibitor, genistein (1 microM), or a protein kinase A inhibitor, H-89 (0.1 microM). These data were consistent with the proadhesive effects of PMA (0.1 microM), a PKC activator; a calcium ionophore, A23187 (1 microM); and dibutyryl cGMP (0.5 and 1 mM); but not phenylarsine oxide (0.1 mM), a tyrosine phosphatase inhibitor, or dibutyryl cAMP (1 mM). Conversely, peroxide-mediated P-selectin expression was blocked by Gö6976 and KT5823, but not by TMB-8. These data are strengthened by the observation that PMA and dibutyryl cGMP, but not A23187, increased P-selectin expression. WEB 2086 (10 microM), a PAF-receptor antagonist, blocked peroxide-, PMA-, and A23187-mediated adhesion, but not peroxide-mediated P-selectin expression. PAF itself (10 nM) stimulated adhesion, but not P-selectin expression. These data indicate that PKC and PKG are involved in peroxide-mediated neutrophil adhesion via P-selectin mobilization and PAF synthesis; however, intracellular calcium appears to mediate adhesion only through PAF synthesis.

Azepines↗
PubMed1999

Studies on interdomain interaction of 3-isopropylmalate dehydrogenase from an extreme thermophile, Thermus thermophilus, by constructing chimeric enzymes.

In our previous study, we showed that a chimeric isopropylmalate dehydrogenase, 2T2M6T, between an extreme thermophile, Thermus thermophilus, and a mesophile, Bacillus subtilis, isopropylmalate dehydrogenases (the name roughly denotes the primary structure; the first 20% from the N-terminal is coded by the thermophile leuB gene, next 20% by mesophile, and the rest by the thermophile gene) denatured in two steps with a stable intermediate, suggesting that in the chimera some of the interdomain interaction was lost by amino acid substitutions in the "2M" part. To identify the residues involved in the interdomain interactions, the first and the second halves of the 2M part of the chimera were substituted with the corresponding sequence of the thermophile enzyme. Both chimeras, 3T1M6T and 2T1M7T, apparently showed one transition in the thermal denaturation without any stable intermediate state, suggesting that the cooperativity of the conformational stability was at least partly restored by the substitutions. The present study also suggested involvement of one or more basic residues in the unusual stability of the thermophile enzyme.

3-Isopropylmalate Dehydrogenase↗
PubMed1999

Expression and localization of the Na+-H+ exchanger in the guinea pig cochlea.

Physiological studies have shown that the Na+-H+ exchanger (NHE) is a major carrier protein regulating the intracellular pH in the cells of the cochlea. The presence of multiple forms of the exchanger has been demonstrated by the recent cloning of four mammalian NHEs, NHE-1 to NHE-4. Despite the structural similarity, these NHE isoforms differ in their tissue distribution, kinetic characteristics, and responses to external stimuli. The present study was undertaken to examine the expression and distribution of four NHE isoforms in the guinea pig cochlea. We used reverse transcription-polymerase chain reaction to assess the expression of NHE-1-4 isoforms and non-radioactive in situ hybridization to examine their localization. Although NHE-2, -3 and -4 isoform mRNAs could be detected in the cochlear tissue, the NHE-1 message was predominant. Cloned guinea pig NHE-1-4 partial cDNA fragments were highly homologous to the corresponding rat NHE isoforms. NHE-1 isoform mRNA was distributed in the hair cells, marginal cells, spiral ligament fibrocytes, spiral prominence cells and spiral ganglion cells. NHE- localized in a variety of cochlear cells would contribute to their differential function.

Amino Acid Sequence↗
PubMed1999

Kinin and histamine stimulate Cl- secretion in gerbil middle ear epithelium: connection to otitis media.

The effects of bradykinin (BK) and histamine on transepithelial ion transport in primary cultures of gerbil middle ear epithelium were investigated. Lysyl-bradykinin (lys-BK) elicited a transient increase in short-circuit current (I(sc)) when added to apical or basolateral surfaces. Lys-BK had a larger effect than BK or des-arg9-BK on both epithelial surfaces. Histamine induced a transient increase in I(sc) only when added to the basolateral surface. Mepyramine, an H1 histamine antagonist, greatly reduced the histamine-induced I(sc). The H2 and H3 histamine antagonists were both ineffective for inhibiting the I(sc) responses to histamine. Diphenylamine-2-carboxylate or 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid, Cl- channel blockers, significantly blocked the I(sc) responses to lys-BK or histamine. The Ca2+-mobilizing action of lys-BK and histamine was also investigated in single middle ear epithelial cells. BK and histamine induced an increase in the intracellular Ca2+ concentration. 1,2-Bis-(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-acetoxymethyl ester, a calcium chelator, greatly reduced the increase in the I(sc) responses to lys-BK or histamine. These data indicate that BK and histamine activate intracellular Ca2+-dependent mechanisms, leading to apical Cl- secretion in the cultured gerbil middle ear epithelium via B2 BK receptors and H1 histamine receptors.

Animals↗
PubMed1999

Prognosis of sudden deafness with special reference to risk factors of microvascular pathology.

OBJECTIVE: We attempted to elucidate the contribution of microvascular disorders as risk factors to the prognostic outcome in well-defined patients with sudden deafness. METHODS: One-hundred and thirty-two patients diagnosed as unilateral sudden deafness were retrospectively analyzed. Auditory function was determined by pure-tone audiometry. Diabetes, hyperlipidemia, and hypertension were considered as microvascular diseases. RESULTS: Concurrent microvascular diseases were recognized in 38 patients. Although the hearing disturbance at the first visit showed no difference from patients without concurrent diseases, a better outcome of hearing was obtained in patients without the concurrent diseases. CONCLUSION: The poor prognosis observed in patients with the concurrent diseases is likely to have been brought about by preexisting microvascular disease of the hearing organ, which is highly affected by aging.

Adult↗
PubMed1999

Unilateral examination of olfactory threshold using the Jet Stream Olfactometer.

OBJECTIVE: The Jet Stream Olfactometer, a modification by the T&T olfactometer, has been recently developed and is now commercially available. This Jet Stream Olfactometer can routinely measure the unilateral sense of smell. Clinical usefulness of the Jet Stream Olfactometer was evaluated. METHODS: Twenty-three patients with sinus-related symptoms were examined. Unilateral olfactory acuity was examined using the Jet Stream Olfactometer and compared it with the anatomy of the olfactory cleft by computed tomographic (CT) scans. RESULTS: In 13 of the 23 patients examined the right olfactory threshold was similar to that of the left. Of these 13, in seven patients there was transport damage of the odorants and in the other six there was sensorineural damage. Ten patients showed an apparent difference between the right and left smell thresholds. Anosmia in seven of these ten patients was due to a conductive olfactory disturbance resulting from rhinosinusitis, whereas sensorineural damage was recognized in the other three patients. The difference in the detection threshold between the right and left nasal cavities was well correlated to that of the opacity between the right and left olfactory clefts. CONCLUSION: Jet Stream Olfactometer provides a convenient and reliable means for assessing the ability of unilateral smell.

Adult↗
PubMed1999

Fibrous membrane formation at the capsular margin in capsule contraction syndrome.

PURPOSE: To determine whether the pathogenesis of capsule contraction syndrome involves the outgrowth of the fibrous membrane from the anterior capsule margin. SETTING: Department of Ophthalmology, Keio University School of Medicine, Tokyo, and the Ando Eye Clinic, Kanagawa, Japan. METHODS: A retrospective review of medical records and slitlamp photographs was conducted in 12 eyes (10 patients) that had required treatment for a narrowed anterior capsule opening after cataract surgery. All patients had had continuous curvilinear capsulorhexis and phacoemulsification with implantation of an intraocular lens in the capsular bag. Specimens of surgically removed fibrous membrane were examined by histopathological methods. RESULTS: Fibrous membrane on the inner surface of the anterior capsule and the linear folds of the anterior capsule were present in each eye. In 10 eyes of 8 patients, the fibrous membrane was on the outer surface of the anterior capsule and covered the capsular folds at its margin. Pathological study showed that this fibrous membrane consisted of the flattened lens epithelial cells that proliferated on the inner and outer surfaces of the shrunken anterior capsule. The outgrowth of this membrane from the margin of the anterior capsule to the center of the opening of the anterior capsule was noted. CONCLUSION: In this study, capsule contraction syndrome involved contraction of the fibrous membrane as well as its outgrowth from the capsule margin.

Actins↗
PubMed1999

Effect of L-arginine infusion on systemic and renal hemodynamics in hypertensive patients.

This study was designed to compare the renal endothelial function in patients with essential hypertension and normal renal function with that in hypertensive patients with renal insufficiency. We studied the effects of L-arginine (500 mg/kg intravenously over 30 min) on renal hemodynamics in 30 normotensive control subjects, 32 patients with mild to moderate essential hypertension who had normal renal function, and seven hypertensive patients with renal insufficiency who had a serum creatinine concentration >2.0 mg/mL and a glomerular filtration rate <50 mL/min/1.48 m2. L-Arginine infusion similarly reduced the mean blood pressure between the three groups (normotensive: -9.7% +/- 0.7%, hypertensives with normal renal function: -10.2% +/- 0.8%, and hypertensives with renal insufficiency: -8.2% +/- 1.3%). The L-arginine-induced decrease in renal vascular resistance was smaller in essential hypertensive patients than in normotensive subjects (-11.0% +/- 2.2 v -19.8% +/- 2.1%, P <.05). However, L-arginine had no effect on the renal vascular resistance in hypertensive patients with renal insufficiency (1.6% +/- 4.8%). Urine nitrite/nitrate levels in response to L-arginine significantly increased in the three groups in the following order: patients with renal insufficiency (47% +/- 15%), essential hypertensive patients (87% +/- 10%), and normotensive subjects (129% +/- 12%). The glomerular filtration rate was unaffected by L-arginine in normotensive and essential hypertensive patients (3.1% +/- 2.4% and 4.2% +/- 2.5%), but significantly decreased in hypertensive patients with renal insufficiency (-13.7% +/- 6.1%). These findings suggest that the ability of the L-arginine-nitric oxide-cGMP pathway to relax the renal vascular tone may be impaired in essential hypertensive patients and more markedly blunted in hypertensive patients with renal insufficiency, in parallel with increasing serum creatinine concentrations.

Arginine↗
PubMed1999

IL-12 receptor beta2 and CD30 expression in paranasal sinus mucosa of patients with chronic sinusitis.

The aetiology of chronic sinusitis is still poorly understood. The expression of T-helper 1 (Th1) and T-helper 2 (Th2) cell markers, interleukin (IL)-12 receptor beta2 subunit (IL-12Rbeta2) messenger ribonucleic acid (mRNA) and CD30, respectively, were investigated in the paranasal sinus mucosa of patients with chronic sinusitis in an attempt to elucidate the involvement of Th1 and Th2 cells in this disease. Anterior ethmoidal mucosae were surgically obtained from two groups of patients with chronic sinusitis: those who had allergic rhinitis (allergic group, n=11) and those without allergy (nonallergic group, n=11). IL-12Rbeta2 mRNA was quantified by means of the reverse transcription polymerase chain reaction, and CD30-positive cells were examined immunohistochemically. Both IL-12Rbeta2 mRNA and CD30 were expressed in the sinus mucosa of the allergic and nonallergic groups. The proportion of mononuclear cells which were CD30-positive in the sinus mucosa was significantly greater in the allergic than in the nonallergic group. The expression levels of IL-12Rbeta2 mRNA were virtually equivalent in both groups. These results suggest a T-helper 2-dominated mucosal reaction in the allergic compared to the nonallergic group, and indicate T-helper 1 activity in the sinus mucosa of both groups. The ubiquity of T-helper 1 cells suggests that they play a role in maintaining local mucosal defences against foreign antigens, which continually enter the upper respiratory tract.

Chronic Disease↗
PubMed1999

Further improvement of the thermal stability of a partially stabilized Bacillus subtilis 3-isopropylmalate dehydrogenase variant by random and site-directed mutagenesis.

A thermostabilized mutant of Bacillus subtilis 3-isopropylmalate dehydrogenase (IPMDH) obtained in a previous study contained a set of triple amino acid substitutions. To further improve the stability of the mutant, we used a random mutagenesis technique and identified two additional thermostabilizing substitutions, Thr22-->Lys and Met256-->Val, that separately endowed the protein with further stability. We introduced the two mutations into a single enzyme molecule, thus constructing a mutant with overall quintuple mutations. Other studies have suggested that an improved hydrophobic subunit interaction and a rigid type II beta-turn play important roles in enhancing the protein stability. Based on those observations, we successively introduced amino acid substitutions into the mutant with the quintuple mutations by site-directed mutagenesis: Glu253 at the subunit interface was replaced by Leu to increase the hydrophobic interaction between the subunits; Glu112, Ser113 and Ser115 that were involved in the formation of the turn were replaced by Pro, Gly and Glu, respectively, to make the turn more rigid. The thermal stability of the mutants was determined based on remaining activity after heat treatment and first-order rate constant of thermal unfolding, which showed gradual increases in thermal stability as more mutations were included.

3-Isopropylmalate Dehydrogenase↗
PubMed1999

Extracellular matrixes influence alpha-smooth muscle actin expression in cultured porcine lens epithelial cells.

PURPOSE: To determine whether extracellular matrix (ECM) influences the expression of alpha-smooth muscle actin (alpha-SMA), a marker for myofibroblasts, in cultured porcine lens epithelial cells (LECs). METHODS: Porcine LECs were cultured for 6 days in an F-12 nutrient mixture supplemented with 5% fetal bovine serum on wells that were coated with laminin, fibronectin, type I collagen, or type IV collagen. LECs cultured on uncoated wells served as a control. Alpha-SMA was detected immunocytochemically with a mouse monoclonal antibody, and the ratio of the number of alpha-SMA-positive cells to the total number of cells, the P/T ratio, was calculated. RESULTS: The P/T ratio of the LECs on the uncoated dishes was about 5%. LECs cultured on wells coated with laminin or type IV collagen significantly reduced the ratio, whereas fibronectin or type I collagen had no effect. CONCLUSIONS: The ECM influences alpha-SMA expression in cultured porcine LECs.

Actins↗
PubMed1999

Flumazenil antagonizes midazolam-induced airway narrowing during nasal breathing in humans.

We measured nasal resistance (Rn) while awake, during midazolam-induced sedation and after antagonism with flumazenil (n = 9). Nasal and oral airflow were measured. Rn was calculated by dividing the difference between maximal nasal mask and oropharyngeal pressures by inspiratory airflow at minimum pharyngeal pressure. During sedation, two subjects developed obstructive apnoeic events and four subjects had snoring events. Each apnoea was ended by mechanisms other than a change in breathing route. After antagonism with flumazenil, apnoeic and snoring events were abolished. Rn during midazolam sedation (median 1.46 (25th percentile 1.00, 75th 2.61) kPa litre-1 s) was significantly greater than before midazolam (0.29 (0.25, 0.48) kPa litre-1 s) and after flumazenil (0.41 (0.25, 0.58) kPa litre-1 s) (P < 0.01 in each subject). We conclude that midazolam increased Rn, sometimes leading to obstruction, and flumazenil abolished this increase in Rn.

Adult↗