Search PubMed⌕ Search

Biomedical subjects

T Oshima

Publications and source records attributed to T Oshima.

At least 109 records · Page 6Linked to original sources
PubMed2000

Abnormal Ca2+ handling and increased Mg2+ permeability in platelets of hypertensive rats.

In order to test the hypothesis that intracellular Na+ accumulation and cellular Mg2+ deficiency may be involved in the abnormalities in Ca2+ handling and reactivity in spontaneously hypertensive rats (SHR) platelets, the metabolism of Na+, Ca2+ and Mg2+ was determined in fluorescent dye loaded platelets from 15 SHR and 15 Wistar-Kyoto rats (WKY) at 12 weeks of age. Mg2+ leak was estimated as the Mg2+ influx induced by an increase in extracellular [Mg2+] (from 1 to 5 mmol/l) and Mg2+/Na+ exchange activity was estimated as the Mg2+ influx induced by a decrease in extracellular [Na+] (from 140 to 50 mmol/l). Cellular metabolism of the fluorescent dye was similar in the two groups. Mean platelet [Ca2+]i was significantly increased under basal and thrombin (0.1 U/ml)-stimulated conditions in SHR compared to WKY, both in the presence and absence of extracellular Ca2+. Mean Ca2+ discharge capacity was similar between the two groups. There was no difference in mean [Na+]i between the two groups. Basal [Mg2+]i was also increased in SHR platelets. Mg2+ leak was higher in SHR than in WKY, while Mg2+/Na+ exchange activity was similar in the two groups. There was no difference in serum Mg2+ concentration between SHR and WKY. These data suggest that abnormal Ca2+ handling is accompanied by elevation in [Mg2+]i via increased permeability of platelet cell membranes to Mg2+ in SHR without any alteration in [Na+]i, and do not support the Mg2+ deficiency hypothesis in genetically hypertensive rats.

Animals↗
PubMed2000

A case report of sinonasal teratocarcinosarcoma.

A sinonasal teratocarcinosarcoma (SNTCS) is a rare and aggressive malignant neoplasm histologically characterized by the combination of one or more epithelial elements and mesenchymal components. We report a case of a 78-year-old man with SNTCS involving the nasal cavity and paranasal sinuses. He complained of epiphora and exophthalmos with weight loss. Physical and diagnostic images resulted T4N0M0. The tumor was completely and widely resected via a trans-facial approach to perform total maxillectomy with orbital exenteration. The clinical presentation, pathologic features, and clinical course are described with a review of the literature.

Aged↗
PubMed2000

Long-term follow-up of obstructive sleep apnea syndrome following surgery in children and adults.

Obstructive sleep apnea syndrome (OSAS) is characterized by recurrent apneas during sleep, resulting in repetitive hypoxemia. The present study retrospectively analyzed subjective and objective assessments of the patients with OSAS in a relatively long-term follow-up. From February 1986 to August 1996, 53 patients received surgical treatment for OSAS and snoring. Thirty-seven (27 males and 10 females) out of 53 patients completed the questionnaire and postoperative sleep study was obtained in 6 patients. In 20 children (<15 years), snoring, sleep apnea, and daytime sleepiness completely disappeared in 12, 19, and 16, and improved in 8, 1, and 4, respectively. These findings confirm that tonsillectomy and/or adenoidectomy in children may be the first selection for treatment. In 17 adults, snoring, sleep apnea, and daytime sleepiness completely disappeared in 2, 5, and 8, improved in 11, 8, and 7, and was unchanged in 4, 4, and 1, respectively. The apnea index in adults was significantly decreased in both early and late postoperative periods. These results suggest that surgery is a satisfactory alternative for adult patients if performed accurate preoperative diagnosis of the localization of the airway collapse and careful long-term follow-up.

Adenoidectomy↗
PubMed2000

Abnormal magnesium status in patients with cardiovascular diseases.

To investigate magnesium status in patients with cardiovascular diseases and in those presenting high factors for these diseases, we measured the concentrations of serum total Mg, serum ionized Mg and intra-erythrocyte Mg. Mg is an important cofactor for many enzymes, especially those involved in phosphate transfer reactions. Mg deficiency has been shown to be associated with fatal cardiovascular diseases, as well as with risk factors for these diseases. Only measurement of the serum concentration of total Mg is routinely available, but ionized Mg is the physiologically active component. Furthermore, most of the body's Mg is present in the intracellular space. Subjects included patients with ischaemic heart disease (n=80), cardiac arrhythmia (n=60), diabetes mellitus (n=36), essential hypertension (n=194) and hypercholesterolaemia (n=60). The same measurements were made in healthy controls (30 men and 26 women; mean age 58+/-11 years). The serum ionized Mg concentration was measured with a selective ion electrode. The intra-erythrocyte Mg concentration was measured by atomic absorption. No gender difference was found for any Mg parameter, nor was age related to any Mg parameter. The serum albumin concentration was positively correlated only with the serum total Mg concentration. Although the serum total Mg concentration was similar in all groups, patients with diabetes mellitus and arrhythmia had lower serum levels of ionized Mg. Patients with essential hypertension exhibited higher intra-erythrocyte Mg concentrations than the healthy controls. Thus the measurement of serum total Mg concentration may obscure the presence of extracellular Mg deficiency in patients with arrhythmia and diabetes mellitus. Furthermore, the intracellular accumulation of Mg does not support the hypothesis of Mg deficiency in patients with essential hypertension.

Biomarkers↗
PubMed2000

[A patient for craniotomy with ECG abnormality occurring on admission to the operating room].

We report a 72 year old male patient for craniotomy with ECG abnormality occurring on admission to the operating room. His preoperative ECG showed normal sinus rhythm without ST-T change and T wave abnormality. On admission to the operating room, negative T wave was noted on the ECG monitor. Therefore, we applied isosorbide dinitrate tape after the induction of anesthesia. When the dura mater was opened, subarachnoid hemorrhage was noticed. Intraoperative pathological examination revealed a glioblastoma multiforme. The tumor bled from inside and outside. The perioperative T wave abnormality was probably due to subarachnoid hemorrhage or bleeding from the tumor itself. The T wave abnormality disappeared on the 10th postoperative day.

Aged↗
PubMed2000

Tranilast inhibits cell proliferation and collagen synthesis by rabbit corneal and Tenon's capsule fibroblasts.

PURPOSE: To determine whether tranilast, N-(3,4-dimethoxycinnamoyl) anthranilic acid, influences cell proliferation and collagen synthesis by rabbit Tenon's capsule fibroblasts (TFs) and corneal stromal fibroblasts (CFs). METHODS: Rabbit TFs and CFs (7000 cells/well) were cultured in F-12 nutrient mixture supplemented with 1% FBS, plus 0, 3, 30, or 300 microM tranilast, and the number of cells was counted 72 hrs later. To determine the effect of tranilast on collagen synthesis, cells at confluence were cultured in a medium containing 0, 3, 30, or 300 microM tranilast and labeled with 3H-proline, and the amount of radioactivity incorporated into collagenase-sensitive proteins was measured. RESULTS: At 300 microM, tranilast decreased the number of TFs by about 27% and the number of CFs by about 45%, but had no effect on cell viability. The same concentration of tranilast reduced TFs collagen synthesis and CFs collagen synthesis. CONCLUSIONS: Tranilast may inhibit scar formation after trabeculectomy for glaucoma and after excimer laser photorefractive keratectomy.

Animals↗
PubMed2000

[Total intravenous anesthesia with Diprivan (1% propofol emulsion) using a manual drip-infusion technique].

Continuous intravenous administration of Diprivan (1% propofol emulsion, P) is usually carried out using a syringe-pump or an infusion-pump to adjust the infusion rate. We assessed the accuracy of the infusion dose of P and the serum concentration of propofol by manual controls during anesthesia. Twenty eight patients, anesthetized with oxygen, P and vecuronium in combination with fentanyl and epidural block were randomly assigned to either of the following groups; P was administered using the drip-infusion (the group D, n = 14) or a syringe-pump (the group S; n = 14). In the group D, we used the drip-rate table to calculate the dose of P. We assessed (1) the total infusion volume of P which was calculated from the infusion rate and duration (Vc), and also measured by a calibrated cylinder (Vm) in the group D (n = 14) and group S (n = 14), and (2) the serum propofol concentrations 40 min after infusion of P (6 mg.kg-1.hr-1) were assayed using the HPLC. The Vc was well correlated with the Vm in the group D (r = 0.976) and in the group S (r = 0.974). Mean serum propofol concentrations of the group D and S were 2.50 +/- 0.57 and 2.35 +/- 0.62 micrograms.ml-1, respectively. The results suggest that the drip-infusion technique of P may be substituted safely by the syringe-pump for continuous total intravenous anesthesia.

Adult↗
PubMed2000

[Evaluation of vascular endothelial function].

Endothelial function was evaluated in renal and forearm vessels from patients with essential hypertension. First, the increase in renal blood flow evaluated by the clearance of para-aminohippurate, serum c-GMP and urinary NOx during L-arginine infusion was significantly attenuated in essential hypertension. This attenuated endothelium-dependent vasodilation was improved by angiotensin converting enzyme inhibitor, but unchanged by calcium antagonist. Second, the increase in forearm blood flow evaluated by plethysmography during acetylcholine infusion or reactive hyperemia was attenuated in essential hypertension. This attenuation was abolished by NO synthesis inhibitor. Forearm endothelial function was improved by angiotensin converting enzyme inhibitor, daily aerobic exercise and body weight reduction by low calorie diet. In conclusion, endothelium-dependent vasodilation was attenuated in renal and forearm vasculature of essential hypertensives via reduction of NO synthesis. This attenuation can be improved by several treatments.

Acetylcholine↗
PubMed1999

Regular aerobic exercise augments endothelium-dependent vascular relaxation in normotensive as well as hypertensive subjects: role of endothelium-derived nitric oxide.

BACKGROUND: Several nonpharmacological interventions, including exercise, are recommended in primary prevention of hypertension and other cardiovascular diseases in which the pathogenetic role of endothelial dysfunction has been suggested. We studied the effects of long-term aerobic exercise on endothelial function in patients with essential hypertension. METHODS AND RESULTS: The forearm blood flow was measured by strain-gauge plethysmography. The responses of forearm vasculature to acetylcholine were smaller in the hypertensive patients than in the normotensive subjects. There was no significant difference in forearm vascular responses to isosorbide dinitrate in the normotensive and hypertensive subjects. We evaluated the effects of physical exercise for 12 weeks on forearm hemodynamics in untreated patients with mild essential hypertension who were divided randomly into an exercise group (n=10) and a control group (n=7). After 12 weeks, the forearm blood flow response to acetylcholine increased significantly, from 25.8+/-9.8 to 32.3+/-11.2 mL. min(-1). 100 mL tissue(-1) (P<0.05), in the exercise group but not in the control group. The increase in the forearm blood flow after isosorbide dinitrate was similar before and after 12 weeks of follow-up in both groups. The infusion of N(G)-monomethyl-L-arginine abolished the exercise-induced enhancement of forearm vasorelaxation evoked by acetylcholine in the exercising group. In normotensive subjects also, long-term aerobic exercise augmented acetylcholine-stimulated nitric oxide release. CONCLUSIONS: These findings suggest that long-term physical exercise improves endothelium-dependent vasorelaxation through an increase in the release of nitric oxide in normotensive as well as hypertensive subjects.

Acetylcholine↗
PubMed1999

Altered cochlear fibrocytes in a mouse model of DFN3 nonsyndromic deafness.

DFN3, an X chromosome-linked nonsyndromic mixed deafness, is caused by mutations in the BRN-4 gene, which encodes a POU transcription factor. Brn-4-deficient mice were created and found to exhibit profound deafness. No gross morphological changes were observed in the conductive ossicles or cochlea, although there was a dramatic reduction in endocochlear potential. Electron microscopy revealed severe ultrastructural alterations in cochlear spiral ligament fibrocytes. The findings suggest that these fibrocytes, which are mesenchymal in origin and for which a role in potassium ion homeostasis has been postulated, may play a critical role in auditory function.

Animals↗
PubMed1999

Structural conservation of the isolated zinc site in archaeal zinc-containing ferredoxins as revealed by x-ray absorption spectroscopic analysis and its evolutionary implications.

The zfx gene encoding a zinc-containing ferredoxin from Thermoplasma acidophilum strain HO-62 was cloned and sequenced. It is located upstream of two genes encoding an archaeal homolog of nascent polypeptide-associated complex alpha subunit and a tRNA nucleotidyltransferase. This gene organization is not conserved in several euryarchaeoteal genomes. The multiple sequence alignments of the zfx gene product suggest significant sequence similarity of the ferredoxin core fold to that of a low potential 8Fe-containing dicluster ferredoxin without a zinc center. The tightly bound zinc site of zinc-containing ferredoxins from two phylogenetically distantly related Archaea, T. acidophilum HO-62 and Sulfolobus sp. strain 7, was further investigated by x-ray absorption spectroscopy. The zinc K-edge x-ray absorption spectra of both archaeal ferredoxins are strikingly similar, demonstrating that the same zinc site is found in T. acidophilum ferredoxin as in Sulfolobus sp. ferredoxin, which suggests the structural conservation of isolated zinc binding sites among archaeal zinc-containing ferredoxins. The sequence and spectroscopic data provide the common structural features of the archaeal zinc-containing ferredoxin family.

Amino Acid Sequence↗
PubMed1999

An efficient gene replacement and deletion system for an extreme thermophile, Thermus thermophilus.

A Thermus thermophilus host strain of which the leuB gene was totally deleted was constructed from a delta pyrE strain by a two step method. First, the leuB gene was replaced with the pyrE gene. Second, the inserted pyrE gene was deleted by using 5-fluoroorotic acid. A plasmid vector with the leuB marker was constructed and the plasmid complemented the leuB deficiency of the host. When the leuB gene from Escherichia coli and its derivative encoding a stabilized enzyme were expressed with the host-vector system, their growth temperature reflected the stability of the enzyme. These results suggest that the gene replacement deletion method using the pyrE gene is useful for the construction of a reliable plasmid vector system and it can be applied to the selection of stabilized enzymes.

3-Isopropylmalate Dehydrogenase↗
PubMed1999

Urea-induced unfolding and conformational stability of 3-isopropylmalate dehydrogenase from the Thermophile thermus thermophilus and its mesophilic counterpart from Escherichia coli.

To reveal the basis of the thermal stability of 3-isopropylmalate dehydrogenase (IPMDH) from an extreme thermophile, Thermus thermophilus, urea-induced unfolding of the enzyme and of its mesophilic counterpart from Escherichia coli has been studied. The urea-induced equilibrium unfolding of T. thermophilus and E. coli IPMDHs at 27 degreesC was monitored by measuring the changes in far-UV CD, intrinsic fluorescence, anilinonaphthalenesulfonic acid (ANS) binding, and catalytic activity in the presence of nonionic detergent Tween 20. For both enzymes, the spectral methods revealed a biphasic unfolding transition. The first transition was protein concentration-independent, whereas the second was protein concentration-dependent for both enzymes. The observation suggested a three-state unfolding mechanism with a dimeric intermediate. However, the intermediates of the E. coli and the T. thermophilus IPMDHs seemed to be different from each other. The intermediate of the E. coli IPMDH lost its secondary and tertiary structure more than that of the thermophilic enzyme. E. coli IPMDH lost enzymatic activity through the transition from the native to the intermediate state, though the intermediate of the T. thermophilus enzyme was still active. The unfolding process of E. coli IPMDH can be explained by a sequential unfolding of individual folding domains, while there is only a small structural perturbation in the intermediate of T. thermophilus IPMDH. The higher thermal stability of T. thermophilus IPMDH can be attributed to the increase in the extent of interaction inside the first domain which unfolded prior to the unfolding of the whole molecular structure in E. coli IPMDH.

3-Isopropylmalate Dehydrogenase↗