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H Sakamoto

Publications and source records attributed to H Sakamoto.

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

Lecithinized superoxide dismutase induces vasodilation; evidence of direct contribution of superoxide anions to modulating vascular tone.

The purpose of this study was to examine the role of superoxide anions in modulating the vascular tone. The effects of unmodified and lecithinized superoxide dismutase (SOD) on vascular tone were determined in aortic ring preparations of mice. In lecithinized SOD, 4 molecules of a phosphatidylcholine derivative were covalently bound to each dimer of recombinant human copper-zinc SOD to facilitate tissue accumulation. Unmodified SOD did not change vascular tone. However, lecithinized SOD induced dose-dependent vasodilation of aortic ring preparations. The pretreatment with NG-nitro-L-arginine methylester (L-NAME) 10(-4) mol/L abolished the vasodilation induced by lecithinized SOD. The results of this study indicate that superoxide anions play a prominent role in modulating the vascular tone by enhancing the breakdown of nitric oxide.

Acetylcholine↗
PubMed1999

Relationship between myocardial tissue density measured by microgravimetry and sound speed measured by acoustic microscopy.

If myocardial tissue can be assumed to be fluid-like, myocardial tissue elasticity can be estimated by the sound speed of tissue based on the equation K = rho(c)2, where K is the elastic bulk modulus, rho is density, and c is the sound speed of tissue. However, little data exist regarding the relationship between the sound speed of tissue and tissue density. The purpose of the present study was to evaluate the relationship between the sound speed of tissue and tissue density of various diseased myocardia. Myocardial tissue specimens at autopsy were obtained from 10 control patients without cardiovascular disease, 8 patients with pressure overload left ventricular hypertrophy (POLVH), and 8 patients with cardiac amyloidosis (AMD). Myocardial tissue sound speed was measured using a scanning acoustic microscope operating in the frequency of 450 MHz, and tissue density was measured by microgravimetry. The sound speed in POLVH (1639 +/- 17 m/s) was higher and that in AMD (1565 +/- 11 m/s) was lower than that in control patients (1615 +/- 15 m/s) (p < 0.001) at the temperature of 20-22 degrees C. The density in POLVH (1.087 +/- 0.004 g/cm3) was higher and that in AMD (1.072 +/- 0.003 g/cm3) was lower than that in control patients (1.082 +/- 0.003 g/cm3) (p < 0.001). Tissue density correlated with sound speed in all three groups (r = 0.96, p < 0.001). Therefore, myocardial tissue sound speed data obtained by acoustic microscopy enabled us to evaluate tissue elasticity without measuring tissue density directly.

Acoustics↗
PubMed1999

Neurons in laminae III and IV of the rat spinal cord with the neurokinin-1 receptor receive few contacts from unmyelinated primary afferents which do not contain substance P.

We have previously demonstrated that neurons in laminae III and IV of the spinal dorsal horn which possess the neurokinin-1 receptor and have long dorsal dendrites receive a major synaptic input from substance P-containing primary afferents and a more limited input from myelinated afferents. In the present study we have carried out a quantitative analysis of the contacts which cells of this type receive from two other classes of unmyelinated primary afferent: those which contain somatostatin and those without neuropeptides. We found that although boutons belonging to both of these types of afferent do form contacts with neurons of this type, the contacts are far less numerous than those formed by substance P-containing afferents. In laminae I and II, the density of contacts which dendrites of these cells received from somatostatin-containing afferents was 1.2/100 microm and that from non-peptidergic C afferents was 2.0/100 microm, which is far lower than our previous estimate of 18.8/100 microm from substance P-containing fibres in these laminae. These results indicate that although the dendrites of large neurons in laminae III and IV which possess the neurokinin-1 receptor pass through regions of the dorsal horn in which many types of primary afferent terminate, their synaptic input from primary afferents is organized in a highly selective manner.

Animals↗
PubMed1999

Reduced production of nitric oxide during haemodialysis.

OBJECTIVE: To examine the influence of systemic nitric oxide (NO) synthesis on blood pressure in patients with chronic renal failure undergoing haemodialysis, since nitric oxides are susceptible to renal excretion or are dialysed, a different indicator that is unaffected by renal function, such as the level of exhaled NO was evaluated. We examined the levels of the endogenous NO before and after a haemodialysis session. DESIGN AND METHODS: We evaluated the serum concentrations of nitrite/nitrate and the rate of nitric oxide release into exhaled air in 10 patients with hypertension who were receiving maintenance haemodialysis. RESULTS: The serum concentrations of nitrite/nitrate before haemodialysis were significantly higher than those in 10 normal controls (183 +/- 151 microM vs 42 +/- 17 microM, P < 0.05). These levels decreased significantly by the end of haemodialysis (42 +/- 26 microM). Because the amount of nitric oxide in the deepest expirate correlated well with the duration of exhalation, we were able to derive the rate of release of NO. The rate of NO release was 0.034 +/- 0.012 nmol/sec before haemodialysis, similar to that in normal controls (0.031 +/- 0.013nmol/sec). The rate was significantly reduced after dialysis (0.023 +/- 0.010 nmol/sec) (P < 0.05). The mean pre-dialysis mean blood pressure (109 +/- 11 mm Hg) and the post-dialysis blood pressure (106 +/- 9 mm Hg) were the same. CONCLUSIONS: These data indicate that NO production does not appear to have a critical role in control of arterial blood pressure across haemodialysis in patients with chronic renal failure.

Adult↗
PubMed1999

Human papillomavirus types 16 and 39 in a vulval carcinoma occurring in a woman with Hailey-Hailey disease.

A woman with Hailey-Hailey disease, suffering from carcinoma of the vulva, was examined by histology and for the presence of human papillomavirus (HPV) DNA by polymerase chain reaction (PCR) and in situ hybridization. Our diagnosis by histological examination revealed the vulval carcinoma to be a squamous cell carcinoma (SCC), adjacent to lesions of Hailey-Hailey disease and severe dysplasia/carcinoma in situ [vulval intraepithelial neoplasia (VIN) III]. The PCR with consensus primers for the L1 region (L1-PCR) successfully amplified HPV DNA using total DNA extracted from formalin-fixed and paraffin-embedded tissue specimens. Restriction fragment length polymorphism analysis and sequencing of L1-PCR products revealed HPV types 16 and 39. HPV 16-specific primers for the E6 region identified HPV 16 DNA. In situ hybridization analysis with biotinylated HPV 16 and 39 DNA probes revealed the presence of the HPV 39 genome in the nuclei of the tumour cells in the SCC. These results indicate that HPV 16 and 39 are associated with lesions in vulval carcinoma. Regarding the patient's susceptibility to infection in the case of Hailey-Hailey disease, there is a possibility that HPV was inoculated into the lesions of Hailey-Hailey disease and induced those of VIN III and SCC.

Aged↗
PubMed1999

Anti-inflammatory effect of roxithromycin in patients with aspirin-intolerant asthma.

BACKGROUND: Fourteen-membered macrolides, such as roxithromycin, have been reported to exhibit other pharmacological activity including anti-asthmatic effects, besides antibiotic activity. OBJECTIVE: This study was designed to investigate the protective effect of roxithromycin on airway responsiveness to the sulpyrine provocation test and to investigate whether this protective activity is associated with a reduction in aspirin-induced excretion of urinary leucotriene E4 (u-LTE4), a marker of cysteinyl leucotriene overproduction that participates in the pathogenesis of aspirin-intolerant asthma. Also, the present study was designed to examine whether or not its anti-asthmatic activity was associated with a reduction in eosinophilic inflammation. METHODS: For 8 weeks before analysis, subjects received 150 mg of roxithromycin or matching placebo twice daily. We assessed the effects of pretreatment with roxithromycin on bronchoconstriction precipitated by inhalation of sulpyrine in 14 adult patients with mild or moderate aspirin-intolerant asthma; those who were in stable clinical condition and were hyperresponsive to sulpyrine provocation test were allocated to this study. A double-blind, randomized, crossover design was used. Urinary LTE4 was measured by a combined reverse-phase high-performance liquid chromatography (rp-HPLC) enzyme immunoassay on sulpyrine provocation testing day. Blood and sputum samples were taken in the morning on the sulpyrine provocation testing day. Eosinophil counting and measurement of eosinophilic cationic protein (ECP) were performed. RESULTS: After the 8 weeks of treatment with roxithromycin, patients' symptoms, blood eosinophils, serum ECP, sputum eosinophils, and sputum ECP were significantly decreased. On the other hand, values of PC20-sulpyrine did not improve after roxithromycin at all. Furthermore, although challenge with sulpyrine caused a significant increase in u-LTE4, pretreatment with roxithromycin or placebo did not affect excretion of u-LTE4. CONCLUSION: Although roxithromycin does not have antileucotriene effects, it has an antibronchial inflammatory effect associated with eosinophilic infiltration. This study raises further interesting therapeutic possibilities and warrants further trials of new approaches to the treatment of aspirin-intolerant asthma.

Adult↗
PubMed1999

Cytoplasmic localization is required for the mammalian ELAV-like protein HuD to induce neuronal differentiation.

BACKGROUND: ELAV-like neuronal RNA-binding proteins are highly conserved in many neurone-containing organisms and have been implicated in neuronal development and differentiation. RESULTS: Mammalian neurone-specific ELAV-like Hu proteins (HuB, HuC and HuD) and Drosophila ELAV, but not HuR, were found to induce neurite outgrowth when over-expressed in rat PC12 cells. Functional analysis of HuD deletion mutants demonstrated the importance of two conserved RNA-binding domains (RBDs 1 and 3) and the indispensability of the linker region between RBDs 2 and 3 for the neurite-inducing activity. Further analyses suggested the importance of nucleocytoplasmic shuttling of HuD mediated by a novel nuclear export signal (NES) sequence in the linker region for the neurite-inducing activity. Moreover, two HuD deletion mutants containing the linker region dominantly inhibited the wild-type neurite-inducing activity, although they had no neurite-inducing activity per se, suggesting that saturable intracellular trafficking mediated by the linker region is required for the neurite induction by HuD. Interestingly, the same dominant negative mutants significantly inhibited retinoic acid-induced neuronal differentiation of mouse embryonal carcinoma P19 cells. CONCLUSIONS: Our results suggest the presence of a novel NES in neurone-specific Hu proteins and the importance of their cytoplasmic localization, through nucleocytoplasmic shuttling, for the initiation of neuronal differentiation.

Amino Acid Sequence↗
PubMed1999

Chemical shift perturbation studies of the interactions of the second RNA-binding domain of the Drosophila sex-lethal protein with the transformer pre-mRNA polyuridine tract and 3' splice-site sequences.

The interactions of the second RNA-binding domain of the Drosophila melanogaster Sex-lethal protein (Sxl RBD2) with the oligoribonucleotides, GUUUUUUUU (GU8) and CUAGUG, representing the sequences surrounding an alternative 3'-splicing site of the transformer pre-mRNA (GU8CUAGUG), were studied using heteronuclear two-dimensional NMR techniques. The 1H and 15N chemical shifts of the backbone amide resonances upon titration of Sxl RBD2 with each of these RNAs were recorded. It was found that Sxl RBD2 can bind not only to the polyuridine tract, GU8, but also to the downstream 3' splice-site sequence, CUAGUG, with similar affinities. In contrast, a nonspecific sequence, C8, did not bind to Sxl RBD2. This result is consistent with previous in vitro RNA-selection and UV-cross-linking results which indicated that the Sex-lethal protein binds to the uridine stretch and the AG dinucleotide in the consensus sequence, AUnNnAGU. In both cases, the chemical-shift perturbations were significant for almost the same amino acid residues, including the two central beta-strands formed by the RNP2-motif and RNP1-motif with the two highly conserved aromatic residues (Y214 and F256) in the middle. As the first RNA-binding domain of Sex-lethal (Sxl RBD1) has a characteristic aliphatic residue at one of the two corresponding positions (I128 and F170), Y214 of Sxl RBD2 was replaced by Ile using site-directed mutagenesis. On the one hand, the 1H and 15N chemical-shift perturbations indicated that GU8 binds to the same interface of mutant Sxl RBD2 as of wild-type Sxl RBD2, although its binding affinity was decreased significantly. On the other hand, the specific binding of Sxl RBD2 to CUAGUG was abolished almost completely by the Y-->I mutation. Taken together, the present results indicate that the interface residues that bind with GU8 and CUAGUG are much the same, but the role of the Y214 residue is clearly different between these two target sequences.

Amides↗
PubMed1999

EUS analysis of collateral veins inside and outside the esophageal wall in portal hypertension.

BACKGROUND: The relation between esophageal varices and venous collaterals outside the esophageal wall in patients with portal hypertension remains unclear. We investigated this relationship with endoscopy and endoscopic ultrasound (US). METHODS: Twenty-two patients with untreated varices were examined. The collaterals were studied with a 20 MHz US catheter probe. Collaterals were divided into two groups: (1) periesophageal collateral veins adjacent to the muscularis externa of the esophagus and (2) paraesophageal collateral veins external to the esophageal wall but without contact with the muscularis externa. Periesophageal and paraesophageal collateral veins were scored as mild or severe according to stage of development. RESULTS: Varix form as defined endoscopically was significantly larger in the severe periesophageal collateral veins group than in the mild periesophageal collateral veins group (p < 0. 01). In contrast, varix form did not differ significantly between the mild and severe paraesophageal collateral veins groups. Perforating veins were detected in the distal esophagus in 18 of 22 patients (81.8%) by means of US. The prevalence of perforating veins increased in relation to varix form. Two types of perforating veins were found on the basis of connection with periesophageal and paraesophageal collateral veins. The frequency with which perforating veins were connected to periesophageal collateral veins was 81.8%; the frequency of connection to paraesophageal collateral veins was 27.3%. CONCLUSION: Periesophageal collateral veins play a more important role in the formation of esophageal varices than do paraesophageal collateral veins.

Adult↗
PubMed1999

Simultaneous measurement of prostaglandin and arachidonoyl CoA formed from arachidonic acid in rabbit kidney medulla microsomes: the roles of Zn2+ and Cu2+ as modulators of formation of the two products.

Under physiological conditions, small amounts of free arachidonic acid (AA) is released from membrane phospholipids, and cyclooxygenase (COX) and acyl-CoA synthetase (ACS) act competitively on this fatty acid to form prostaglandins (PGs) and arachidonoyl-CoA (AA-CoA). To date, there is no information about the factors deciding the metabolic fate of free AA into these two pathways. In this study, we tried to establish a method for the simultaneous measurement of PG and AA-CoA synthesis from exogenous AA in microsomes from rabbit kidney medulla. The kidney medulla microsomes were incubated with [14C]-AA in 0.1 M-Tris/HCI buffer (pH 8.0) containing cofactors of COX (reduced glutathione and hydroquinone) and cofactors of ACS (ATP, MgCl2 and CoA). After incubation, PG (as total PGs), AA-CoA and residual AA were separated by selective extraction using petroleum ether and ethyl acetate. When 60 microM AA was used as the substrate, indomethacin (an inhibitor of COX) and triacsin C (an inhibitor of ACS) reduced only PG and AA-CoA formation, respectively. On the other hand, when 5 microM AA was used as the substrate, indomethacin and triacsin C came to increase significantly the AA-CoA and PG formation, respectively. Thus, the experiments utilizing indomethacin and triacsin C revealed that the incubation using 60 microM AA can simultaneously detect the changes in the activities of COX and ACS caused by drugs, while the incubation using 5 microM AA can detect the changes in the product formation elicited by the resulting shunt of AA. Further, using these incubation conditions, the effects of Zn2+ and Cu2+ on the PG and AA-CoA formation were examined. Zn2+ inhibited the AA-CoA synthesis from 60 microM AA without affecting the PG synthesis. In contrast, when 5 microM AA was used as the substrate, a significant increase in the PG formation was observed in the presence of this ion, indicating that drug actions on the PG formation from AA by the kidney medulla microsomes may change depending on the substrate concentration. On the other hand, Cu2+ increased PG synthesis and inhibited AA-CoA synthesis from both 60 and 5 microM AA. These results suggest that the simultaneous measurements of PG and AA-CoA formation by the kidney medulla microsomes under high (60 microM) and low (5 microM) substrate concentrations can investigate the direct and indirect actions of drugs on the COX and ACS activities, and are useful for clarifying the haemostatic control of the metabolic fate of AA into the two enzymatic pathways. Furthermore, this study showed that Zn2+ and Cu2+ can modulate PG and AA-CoA formation by affecting COX activity, ACS activity, and/or the AA flow into the two enzymatic pathways.

Acyl Coenzyme A↗
PubMed1999

Analysis of elastin metabolism in patients with late-onset focal dermal elastosis.

Late-onset focal dermal elastosis has recently been described as new clinical entity characterized by pseudoxanthoma elasticum-like eruptions and an accumulation of normal-appearing elastic fibres in the dermis. Elastin and collagen contents of the skin of 2 patients were 2- and 1.4-fold higher than in the skin of controls, respectively. A focal accumulation of elastin but not of fibrillin-1 was observed by immunohistochemical staining. The levels of type I and III collagen and elastin mRNAs isolated from cultured patient fibroblasts were elevated 2-3-fold compared with control fibroblasts. There was no significant change in the excretion of elastin peptides in the urine of patients and controls. These results suggest that the focal accumulation of elastic fibres in the patient skin may be related to overexpression of elastin rather than to altered degradation of elastin.

Age of Onset↗
PubMed1999

The need for long-term treatment in the mouse lymphoma assay.

The L5178Y tk +/- mouse lymphoma assay (MLA) has been widely used as a genotoxicity test for the detection of mutagens and clastogens. The standard MLA, as well as other mammalian cell gene mutation assays, usually employs a short treatment period (3-6 h). Our previous report, however, suggested that such short treatments may be insufficient for detecting some clastogens and spindle poisons. For the present study, we introduced and evaluated a longer treatment (24 h) in the MLA. We examined 15 chemicals which were evaluated as negative or inconclusive in the short-term study. Cells were exposed to the chemical for 24 h without S9 mix, cultured for 2 days and then thymidine kinase-deficient mutants were selected in 96-well microtiter plates under trifluorothymidine. Eleven chemicals yielded positive responses in the 24 h treatment MLA. They included nucleoside analogs (2'-deoxycoformycin and dideoxycytidine), a base analog (1,3-dimethylxanthine) and spindle poisons (colchicine and vinblastine sulfate), all of which do not directly affect DNA, but bring about mutations and chromosome alterations through nucleoside metabolism and chromosome segregation. Because the mutagenicities of these non-DNA targeting chemicals appear to be cell cycle dependent, treatment extending over more than one cell cycle may be required for their effect. Combining results from the present and previous studies, 31 of 34 (91%) chromosome aberration-positive chemicals exhibited positive responses in the MLA, suggesting that the sensitivity of the MLA with 24 h treatment periods approaches that of the chromosome aberration test.

Animals↗
PubMed1999

A proposal for a simple way to distinguish aneugens from clastogens in the in vitro micronucleus test.

In our previous in vitro micronucleus (MN) study, we showed that aneugens, in addition to inducing micronuclei, induce a higher frequency of polynuclear (PN) and mitotic (M) cells than clastogens. We hypothesized that the frequency of PN and M cells induced can distinguish aneugens from clastogens. To test the hypothesis, we conducted the micronucleus tests with mitomycin C (MMC), N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), vincristine (VINC) and diazepam in a Chinese hamster cell line (CHL) and VINC, benzo[a]pyrene (BP) and 7,12-dimethylbenz[a]anthracene (DMBA) in a subclone of V79 cells (V79-MZ). All chemicals increased the frequency of M cells with statistical significance. All chemicals except diazepam increased the frequency of PN cells with statistical significance. Three of the aneugens (VINC, BP and DMBA) induced >/=200 PN cells/1000 cells while the clastogens (MNNG and MMC) induced 100 PN cells at most. All the aneugens but no clastogens significantly increased the frequency of M cells. We propose that micronucleus test-positive chemicals that induce >/=200 PN cells/1000 cells and significantly increase the frequency of M cells are aneugens and those that induce at most 100 PN cells/1000 cells and do not significantly increase the frequency of M cells in our MN test protocol are clastogens. Diazepam, however, did not induce PN cells, although it increased the frequency of M cells dose dependently. We explain this fact in relation to diazepam's mode of action. Our proposal suggests a quick, easy and practical way to distinguish aneugens from clastogens for screening purposes.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1999

NMR signal assignment of the polyuridine tract of the single-stranded RNA complexed with Sxl RBD1-RBD2 by using residue selective [5-(2)H]uridine substitutions.

Using [5-(2)H]uridine phosphoramidite, we synthesized a series of 2H-labeled Drosophila Sex-lethal (Sxl) target RNAs, in which all the uridine residues except one were specifically replaced by [5-(2)H]uridine. By observing the H5-H6 cross peaks of RNA in the TOCSY spectra, we unambiguously assigned all the base proton resonances of the target RNA in a Sxl x RNA complex. Furthermore, it was shown that Sxl differently recognizes A and G in a position prior to the polyuridine tract.

Animals↗
PubMed1999

Effect of intracellular glutathione on the production of prostaglandin D2 in RBL-2H3 cells oxidized by tert-butyl hydroperoxide.

The liberation of arachidonic acid and the production of prostaglandin D2 (PGD2) were significantly influenced by peroxide and the level of intracellular glutathione (GSH). The productions of free arachidonic acid and PGD2 in RBL-2H3 cells were enhanced considerably by exposure to tert-butyl hydroperoxide (t-BHP). The liberation of arachidonic acid induced by t-BHP was not inhibited by EGTA. The productions of PGD2 and arachidonic acid induced by t-BHP were significantly facilitated by the depletion of intracellular GSH using buthionine sulfoximine (BSO) or diethyl maleate (DEM), although the depletion of GSH had no effect on the production of PGD2 induced by A23187. t-BHP failed to activate the conversion of free arachidonic acid to PGD2, since the formation of PGD2 from exogenously added arachidonic acid was not enhanced by treatment with t-BHP. The level of lipid hydroperoxides in t-BHP-treated cells was significantly elevated by treatment with DEM. These results suggest that hydroperoxides increase the free arachidonic acid available for the synthesis of PGD2 by activating phospholipase A2 (PLA2) and that the depletion of GSH by DEM accelerates the activation of PLA2 by raising peroxide levels in cells. Thus, the observed alterations in GSH levels are large enough to cause increased PGD2 synthesis in RBL-2H3 cells exposed to oxidative stress.

Animals↗
PubMed1999

Utility of digital camera-derived intraoperative images in the planning of epilepsy surgery for children.

OBJECTIVE: This study was undertaken to assess the utility of digital camera-derived intraoperative images in the planning of neurosurgery for children with epilepsy. METHODS: A hand-held digital camera was used to capture the exposed surgical field at the time of craniotomy for 11 children with medically intractable seizure disorders. Intraoperative somatosensory evoked potential recordings of phase reversals and direct cortical stimulation were used to map areas of eloquent brain tissue. Digital camera images were obtained to mark regions of functional brain tissue with respect to cortical surface landmarks and subdural grid placement. The digital camera images were then immediately downloaded, in the operating room, to a laptop computer, which was placed next to the electroencephalographic recording device. Using computer software, the epileptologist highlighted the primary and secondary zones of epileptogenesis, as well as the functional brain areas identified during the monitoring period, on the digital camera images on the computer screen. A neurosurgical map was thus created to aid the neurosurgeon and the epileptologist with the proposed cortical resections and multiple subpial transections. RESULTS: With the images obtained using the digital camera, the epilepsy team was able to observe the contacts of the grid electrodes with the brain during the procedure. Color printouts of the images served as references during the period of invasive monitoring. Zones of primary and secondary epileptogenesis, as well as areas of functional brain tissue, were identified and plotted on the digital camera images. Other benefits of the digital camera-derived images included the ability to accurately reposition the grids or letters marking eloquent brain tissue if they were inadvertently shifted during the procedure, the ease with which the images could be obtained and manipulated, the ability to assess postresection epileptiform activity of the surrounding brain tissue with images obtained while an electrocorticographic array was in place, the ability to provide the entire epilepsy team with updated information on the neurosurgical field while minimizing movement in the operating room, and facilitation, with neurosurgical maps, of discussions with the patients and their families concerning proposed cortical resections. CONCLUSION: Digital camera images have become essential components for the planning of cortical resections for children with intractable epilepsy at our institution. We envision widespread application of this technology to other neurosurgical fields.

Adolescent↗