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H Tokunaga

Publications and source records attributed to H Tokunaga.

At least 55 records · Page 3Linked to original sources
PubMed2000

Sodium-dependent calcium release from vascular smooth muscle mitochondria.

Interest in mitochondrial calcium (Ca2+) uptake and release waned as it became apparent that sarcoplasmic reticulum calcium stores dominate the control of cytoplasmic calcium concentration. Our recent demonstration of a very large rise in vascular smooth muscle (VSM) cytoplasmic sodium (Na+) concentration after inhibition of the sodium, potassium-ATPase (sodium pump) led us to several questions. Do VSM mitochondria show Na(+)-dependent Ca2+ release? Are the documented changes in cytoplasmic Na+ concentration sufficient to cause Ca2+ release? Do features of the cardiac mitochondrial exchange system, including differential sensitivity to a number of calcium antagonists and cation specificity, apply to VSM? We isolated mitochondria from bovine aorta and mesenteric arteries and employed arsenazo III as the Ca2+ indicator. Mitochondria from arterial vessels accumulated added calcium (up to 50 nmol Ca2+/mg protein) and released Ca2+ on exposure to Na+. This concentration-dependent relationship was linear from 0 to 10 mM of Na+, and it plateaued between 20 mM and 40 mM of Na+. VSM mitochondria exposed to 20 mM Na+ released 118 +/- 25 nmol Ca2+ per mg mitochondrial protein in 20 min, when a new equilibrium was reached. Lithium (Li+), in contrast to Na+, produced much smaller amounts of Ca2+ release from the VSM mitochondria. Na+-dependent Ca2+ release was antagonized in a concentration-dependent manner by diltiazem (0-320 microM) with a Ki of 10.2 microM. Nifedipine had a lesser effect, and verapamil produced almost no inhibition. VSM mitochondria responses resemble those from heart mitochondria in that Na+-dependent Ca2+ release is present with a similar range of sensitivity to Na+ and a similar pattern of influence of diltiazem, nifedipine and verapamil. However, the influence of Li+ on Ca2+ release was much smaller and the amount of the Ca2+ released was much greater for VSM mitochondria compared with that reported for heart mitochondria. The large amount of Ca2+ released and the range of Na+ concentration that provoked Ca2+ release being within the physiologically achievable range raise the interesting possibility that these mechanisms may modify intramitochondrial cytosolic Ca2+ concentration, and hence could potentially contribute to the contractile response that follows inhibition of the sodium pump.

Animals↗
PubMed2000

[The correlation between the exacerbation of bronchial asthma and picornavirus (human rhino virus) infection in throat gargles by RT-PCR].

Viral infection is one of important factors to cause the exacerbation of bronchial asthma. We have investigated 167 adults of asthmatics to clarify the correlation between viral infection and exacerbation of asthma. Patients were classified to four group by the symptoms of common cold and asthma attack. Furthermore, we have examined Picornavirus and Human rhino virus RNA from throat gargles of patients using RT-PCR (reverse transcription--polymerase chain reaction) method. Forty of 65 (61.5%) asthmatics with common cold revealed asthma attack and common cold was significantly associated with acute exacerbation of asthma (p < 0.01). We identified Picornavirus RNA, which include 113 of Human rhino virus serotypes and enterovirus, from the samples of 16 of 52 (30.8%) patients who had acute exacerbation. It was significantly higher than the detection rate of viral RNA from patient without asthma attack. Furthermore, we analyzed Human rhino virus RNA from the same samples by RT-PCR and 93.7% of Picornavirus were identified as Human rhino virus. Taken together, these findings suggest that common cold is significantly associated with the exacerbation of bronchial asthma. Human rhino virus infection might be one of important virus in this procedure.

Adult↗
PubMed2000

[VEGF is an essential molecule for glomerular endothelial cells and its excretion in urine might be a unique marker of glomerular injury].

A glomerulus is a functional unit of the kidney, and endothelial cells in the glomerulus are often exposed to more than 5 times higher pressure than peripheral capillaries. Glomerular development proceeds through angiogenesis and VEGF was shown to mediate the angiogenesis. VEGF is constitutively expressed in the glomerulus from the embryo to adults. When VEGF signal was blocked by the antibody, glomerular endothelial cells were swollen and capillary lumen was interrupted. Changes were more prominent in the juxta-medullary than in the cortical glomerulus. A major VEGF receptor, Flk-1/KDR, is specifically localized to the glomerular endothelial cell among tissues and more predominantly in the juxta-medullary than in the cortical glomerulus. As capillary pressure is higher in the juxta-medullary than in the cortical glomeruli, endothelial cells in the former are exposed to more tension than those in the latter. VEGF might be a protective molecule for endothelial cells against tension. The effect of VEGF on the repair of an impaired glomerulus was evaluated in the rat Thy-1 glomerulonephritis. VEGF inhibited early endothelial injury and accelerated consequent remodeling of the glomerulus. In the patient study, VEGF excretion in the urine was independent from its serum or plasma level, but increased as renal function decreased. VEGF signaling is essential in glomerular development, maintenance and repair. VEGF excreted in the urine might reflect its generation in the kidney and be a unique marker of renal function.

Animals↗
PubMed2000

[Validation of simple analytical equipment for arsenic].

In order to improve the arsenic test method, we investigated the effect of temperature, solar light and masking ions on that test method. As the results, we found that the solar light gave the big damage to the colored reaction on the method. In addition, on comparing the improved method with the arsenic test method of Merckoquant kit by using the water containing 0.01 ppm arsenic as the Japanese guideline for the drinking water, the improved method gave the better analytical value than Merckoquant kit that was not sufficiently determined.

Arsenic↗
PubMed1999

Different neural substrates for Kanji and Kana writing: a PET study.

To investigate the neural substrate underlying the mechanisms of Kanji and Kana writing, we conducted a PET activation study during mental writing task in eight right-handed normal Japanese subjects. During scans subjects were required to mentally write a Kanji or three Kana letters with their right hand, for each stimulant word presented auditorily. The direct comparisons between Kanji writing and Kana writing revealed that the left posterior inferior temporal gyrus was activated in Kanji writing while the left angular gyrus was activated in Kana writing. In addition, more extensive areas were activated in Kanji writing compared with Kana writing. These results suggest that different respective neural substrates are involved in Kanji and Kana writing respectively.

Adolescent↗
PubMed1999

Liquid chromatography-fast atom bombardment mass spectrometry for detection and determination of pentazocine in human tissues.

A reliable and sensitive method was developed for the detection and determination of pentazocine in human solid tissues using liquid chromatography-dynamic fast atom bombardment (FAB) mass spectrometry, combined with a three-step liquid-liquid extraction procedure. Levallorphan tartrate served as an internal standard. The extract was evaporated to dryness and dissolved in the mobile phase, acetonitrile-10 mM ammonium acetate solution (20:80, pH 4.0) containing 0.5% glycerol as FAB matrix. The eluent was pumped at a flow rate of 25 microl/min and split before introduction to FAB mass spectrometer. Quantitative analysis was carried out by means of monitoring quasi-molecular ions with m/z 286 for pentazocine and m/z 284 for levallorphan. The lower limit of detection of pentazocine in each tissue tested was 1 ng/g with scan mode and 0.1 ng/g with SIM mode. Using this method, the concentrations of pentazocine were determined in the tissues of an autopsied individual to perform toxicological evaluation.

Aged↗
PubMed1999

Level of retinoblastoma protein expression correlates with p16 (MTS-1/INK4A/CDKN2) status in bladder cancer.

Recent studies have shown that patients whose bladder cancer exhibit overexpression of RB protein as measured by immunohistochemical analysis do equally poorly as those with loss of RB function. We hypothesized that loss of p16 protein function could be related to RB overexpression, since p16 can induce transcriptional downregulation of RB and its loss may lead to aberrant RB regulation. Conversely, loss of RB function has been associated with high p16 protein expression in several other tumor types. In the present study RB negative bladder tumors also exhibited strong nuclear p16 staining while each tumor with strong, homogeneous RB nuclear staining were p16 negative, supporting our hypothesis. To expand on these immunohistochemical studies additional cases were selected in which the status of the p16 encoding gene had been determined at the molecular level. Absent p16 and high RB protein expression was found in the tumors having loss of heterozygosity within 9p21 and a structural change (mutation or deletion) of the remaining p16 encoding gene allele, confirming the staining results. These results strongly support the hypothesis that the RB nuclear overexpression recently associated with poor prognosis in bladder cancer is also associated with loss of p16 function and implies that loss of p16 function could be equally deleterious as RB loss in bladder and likely other cancers.

Biopsy↗
PubMed1999

Delayed postoperative CSF rhinorrhea of intrasellar arachnoid cyst.

CSF rhinorrhea due to a transsphenoidal approach usually follows accidental or intentional arachnoid opening. We report a patient with an intrasellar arachnoid cyst, who developed delayed onset of CSF rhinorrhea. A sixty-two-year-old man presented with bitemporal type visual field defect for the last 3 years. With the diagnosis of arachnoid cyst or Rathke's cleft cyst, based on MRI findings of intra-and supra-sellar cyst with CSF intensity, he successfully underwent transsphenoidal surgery without evidence of intra-operative CSF leakage. He developed CSF rhinorrhea one week later. This needed another operation for sellar floor repair. The pathomechanism of this delayed onset is explained as follows. Incomplete or oneway communication of subarachnoid space to cyst cavity, unrecognized during surgery, might cause delayed onset of CSF rhinorrhea. By using MRI, identification of the residual gland, which was compressed posteriorly, is useful for differentiating an arachnoid cyst from other cystic lesions. In highly suspect cases, even without evidence of intra-operative CSF leakage, peri-operative measures to prevent occurrence of postoperative CSF rhinorrhea are required.

Arachnoid Cysts↗
PubMed1999

Identification and partial purification of DnaK homologue from extremely halophilic archaebacteria, Halobacterium cutirubrum.

The levels of synthesis of six proteins were increased at elevated growth temperature of the extremely halophilic archaebacterium Halobacterium cutirubrum. One of these proteins, with an apparent molecular mass of 97 kDa on sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE), bound to an ATP-agarose column in the presence of 4 M NaCl, but not in the absence of salt, indicating that this protein retained its ATP-binding activity only at high salt concentration. The NH2-terminal sequence of this protein and the internal sequences of the tryptic peptides covering 1/3 of the total number of residues coincided with that deduced from the nucleotide sequence of the dnaK gene isolated from H. cutirubrum. The results strongly suggest that this apparent 97-kDa protein is the gene product of dnaK, although the molecular mass calculated from the nucleotide sequence is only 68,495, much smaller than the value of this protein determined by SDS-PAGE. Ferguson plot analysis indicated that this protein showed anomalous mobility on SDS-PAGE. We have purified DnaK homologue to greater than 90% homogeneity with stepwise elution from an ATP-agarose column.

Amino Acid Sequence↗
PubMed1999

Multiple aortocaval fistulas associated with a ruptured abdominal aneurysm in a patient with Ehlers-Danlos syndrome.

Aortocaval fistula (ACF) is a rare complication of spontaneous abdominal aortic aneurysm (AAA) rupture, with an incidence of 2-4%. A unique case of ruptured AAA complicated by multiple aortovenous fistulas involving the inferior vena cava and left internal iliac vein is presented, and is the first published report of a patient with Ehlers-Danlos syndrome undergoing surgical treatment for an ACF.

Aneurysm, Ruptured↗
PubMed1999

The loss of expression of transforming growth factor-beta receptors correlates with the histopathologic tumor grade in bladder transitional cell carcinoma patients.

Transforming growth factor-beta (TGF-beta), a pleiotropic growth factor, is a potent inhibitor of cellular proliferation in cells of epithelial origin. Recently, it has been suggested that a loss of sensitivity to TGF-beta through a loss of expression of TGF-beta receptors T beta R-I and T beta R-II--is associated with tumor initiation and progression. Therefore, to investigate the relationship between TGF-beta receptors expression and carcinogenesis of bladder TCC, this study examined the expression of T beta R-I and T beta R-II in 46 bladder TCC patients using immunohistochemistry. Since histopathological grade is a widely accepted marker of prognosis, the results were compared in relation to the three grades of bladder TCC. The results demonstrated that the loss of TGF-beta receptors expression is associated with increasing histopathological grades of bladder TCC. Specifically, both T beta R-I and T beta R-II were readily detected in all 10 normal bladder mucosa specimens. Likewise, all 6 specimens of grade I TCC samples expressed high levels of both TGF-beta receptors. However, among grade II TCC samples, T beta R-I and T beta R-II were detected in 78% and 89%, respectively: among grade III TCC samples, T beta R-I and T beta R-II were detected in 45% and 41%, respectively. These results suggested that loss of sensitivity to TGF-beta may play a role in the progression of TCC from low to high grade disease.

Adult↗
PubMed1999

[A case of pure agraphia with a deficit of drawing].

We examined a drawing ability in a case with pure agraphia. The patient, having lesions in the left middle frontal gyrus and inferior parietal lobule, could not write in both dictation and spontaneous writing tasks, with the ability to copy letters being well spared. Correspondingly, he showed a deficit of spontaneous drawing, with the ability to copy complex figures being well spared. These findings suggest that he could have an impairment of retrieving visual image, not restricted to letter image. Although some previous cases with pure agraphia were attributed to an impairment of retrieving visual letter image, drawing ability which seemed to be related to retrieving visual image had not been investigated. In the present case, disability of both writing and drawing could be attributed to a common mechanism, that was an impairment of retrieving visual image. In addition, the patient did not show a significant difference between the performance on Kana writing and on Kanji writing. But it has been said that an impairment of retrieving visual letter image could be related to a deficit of Kanji writing more than of Kana writing. Then, it could be assumed that the mechanism of Kana writing involved not only the pathway depending on graphical motor pattern but one depending on visual image.

Agraphia↗
PubMed1999

Decreased expression of transforming growth factor beta receptor type I is associated with poor prognosis in bladder transitional cell carcinoma patients.

Transforming growth factor (TGF) beta, a potent growth inhibitor of proliferation in most cells, usually exerts its effects through an interaction with membrane receptors, type I (TbetaR-I) and type II (TbetaR-II). In the present study, the expression of TGF-beta receptors was correlated with tumor grade, pathological stage, and probability of progression and survival in patients with bladder transitional cell carcinoma (TCC). To this end, immunohistochemistry was carried out in specimens obtained from 59 patients who underwent either radical cystectomy or transurethral resection of bladder tumor. Among these patients, 18 (30.5 %) had loss of TbetaR-I expression, whereas 27 (44.0%) had loss of TbetaR-II expression. There was a correlation between the loss of expression of TbetaR-I and TbetaR-II and the tumor grade (P = 0.041 and P = 0.026, respectively). In addition, both pathological and lymph node status also were associated with the loss of TbetaR-I and TbetaR-II expression (P = 0.025 and P = 0.004, respectively). Interestingly though, only the loss of expression of TbetaR-I was associated with an increased probability of tumor progression and a decreased probability of survival (P = 0.0046 and P = 0.0022, respectively). These results suggest that the status of TbetaR-I expression may be a potential prognostic marker in patients with bladder TCC.

Activin Receptors, Type I↗
PubMed1999

Perception and conception: separate memory systems in the medial temporal lobe.

The purpose of the present study was to investigate, by using positron emission tomography, whether the functionally different types of information are subserved by different memory systems in human medial temporal lobe structures. Before explicit retrieval tests during scans, subjects studied words in perceptually and conceptually processed manners separately. It was found that different parts of the medial temporal lobe structures were involved in each of the different conditions. These results indicated that perceptually and conceptually processed types of information were subserved by at least two partially segregated memory systems in human medial temporal lobe structures.

Adult↗
PubMed1999

[Catecholamine].

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Adolescent↗
PubMed1998

Molecular cloning of the dnaK locus, and purification and characterization of a DnaK protein from Bacillus brevis HPD31.

Using part of the dnaK gene from Bacillus subtilis as a probe, a 4. 4-kbp SacI-BglII fragment of chromosomal DNA of Bacillus brevis, a protein-hypersecreting bacterium, was cloned. Nucleotide sequencing revealed 3 open reading frames in the order of grpE-dnaK-dnaJ homologues. We purified DnaK protein to homogeneity from B. brevis HPD31 harboring a multi-copy dnaK expression plasmid. Purified DnaK showed ATPase activity which was synergistically stimulated 14-fold by the addition of glutathione S-transferase-DnaJ and glutathione S-transferase-GrpE fusion proteins. DnaK hydrolyzed not only ATP but also CTP, UTP, and GTP at about 40% of the efficiency of ATP. The specific activity of DnaK-ATPase was 7.25x10-3 unit/mg protein (the turnover number against ATP was 0.47 min-1) under our assay conditions. The DnaK dimers dissociated into monomers on addition of ATP, GTP, CTP, UTP and ATPgammaS, but not ADP or AMP. DnaK formed a stable complex with permanently unfolded carboxymethylated alpha-lactalbumin but not with native alpha-lactalbumin, and this complex was dissociated by addition of ATP/Mg. Formation of this complex was inhibited in the presence of inorganic phosphate.

Adenosine Triphosphatases↗
PubMed1998

Effect of preceding in vivo sublethal ischemia on the evoked potentials during secondary in vitro hypoxia evaluated with gerbil hippocampal slices.

We investigated the mechanism of 'ischemic tolerance phenomenon' by characterizing the physiological events, modified by preceding sublethal ischemia, during secondary hypoxia. Slices from brains after pretreatment of sublethal forebrain ischemia were subjected to a 70% reduction of PO2 (threshold hypoxia). Although evoked potentials disappeared completely in five of eight slices from sham-operated brain, they were sustained in 28/32 slices from pretreated brains. This study indicates that the maintenance of membrane function might be the mechanism of ischemic tolerance.

Animals↗