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Biomedical subjects

Y Yamazaki

Publications and source records attributed to Y Yamazaki.

At least 271 records · Page 15Linked to original sources
PubMed1998

[Regional cerebral blood flow and oxygenation following cervicothoracic sympathetic block].

Stellate ganglion block (SGB) is considered to increase blood flow to the governing area, but recent studies have shown the decrease of common carotid arterial blood flow in the unblocked side following SGB. We investigated the influence of SGB on bilateral cerebral blood flow and oxygenation using a regional oxygen saturation (rSO2) monitor, TOS-96 (TOSTEC, Japan). The changes of blood volume (hemoglobin index: Hb I) and rSO2 were measured in twenty adult patients who underwent SGB at the transverse process of the C 6 vertebra. Prior to the investigation, two sensors were calibrated and placed on either side of each patient's forehead in order to see the difference. There were significant increases in rSO2 and Hb I in the blocked side and decreases in rSO2 and Hb I in the contralateral side. These results suggest that blood flow in the blocked side following SGB increases with decreased blood flow in the unblocked side. Patients with cerebral vascular disease undergoing SGB might be at risk of a decrease in cerebral blood flow in the unblocked area.

Adult↗
PubMed1998

[Prevalence and a drug use development model for the study of adolescent drug use in Japan].

The purposes of this study were to estimate the prevalence of drug use, to examine the correlation between drug use and drinking/smoking in Japan, and to test a developmental model of adolescents' drug use based on three basic theories of deviance: Strain, Social control, and Differential association. The survey was conducted from April to May, 1996, in 14 public high schools in Tokyo, using anonymous self-reporting. A total of 4,171 (99.45%) students responded to our questionnaire. It included central concept items in the three deviant theories, beliefs about the ill effects of drugs, sex, grades, etc. The following findings were obtained: 1) Among the subjects, 255 students (6.1%) reported drug use within the past year. Of these drug users, 73.3% used drugs soon after being "tempted" by friends. Responding to "When was it.", as a first year junior high school was the most common first experience, and the next most common was during the sixth year of elementary school. 2) Drinking and smoking appeared to be gateway drugs for adolescents in Japan as has been shown in the United States. 3) Multiple regression and logistic multiple regression analyses suggested that differential association variables were far more powerful predictors of adolescent drinking, smoking and drug use than either the control or strain variables. Results provided modest support for the Differential Association Theory as an explanation of drug use. 4) LISREL's goodness-of-fit statistic indicated a much better fit between the model and the data. (CN: 282, GFI: 0.967, AGFI: 0.941). These findings show two processes by which adolescents become involved in drug use. Strain and Social Control do not directly affect drug use. However, Social Control is important because it works indirectly, through Differential Association resulting in drug use. Second, though weaker, Differential Association appears to lead to dangerous beliefs in drug use followed by actual drug use.

Adolescent↗
PubMed1997

Title not supplied by PubMed (PMID 11091618)

A comparative study of &sup201;Tl and &sup99m;Tc-methoxy-2 isobutyl isonitrile (&sup99m;Tc-MIBI)was performed in 39 breast tumors. &sup201;Tl scintigraphy was carried out in 24 breast tumors and &sup99m; Tc-MIBI scintigraphy in 15. The sensitivity of &sup201;Tl for malignant tumors was 100%(22/22), but specificity was 0%(0/2). On &sup99m;Tc-MIBI scintigraphy, the sensitivity for malignant tumors was 83.3%(10/12) and specificity was 100%(3/3). &sup99m;Tc-MIBI might be more useful for the diagnosis of breast tumors, because the tumor/background ratio of &sup99m;Tc-MIBI was significantly higher than that of &sup201;Tl. In addition, &sup201;Tl scintigraphy and &sup99m;Tc-MIBI scintigrtaphy showed the same degree of accuracy (93.3%) in detecting lymph node metastasis. Moreover, when either ultrasonography (US) with &sup201;Tl or &sup99m;Tc-MIBI scintigraphy was positive for lymph node metastasis, the accuracy of detection became 94.4% The combined use of ultrasonography and scintigraphy might improve the accuracy of diagnosis of lymph node metastasis.

Journal Article↗
PubMed1997

Time-resolved fourier transform infrared study of structural changes in the last steps of the photocycles of Glu-204 and Leu-93 mutants of bacteriorhodopsin.

The last intermediate in the photocycle of the light-driven proton pump bacteriorhodopsin is the red-shifted O state. The structure and dynamics of the last step in the photocycle were characterized with time-resolved Fourier transform infrared spectroscopy of the mutants of Glu-204 and Leu-93, which accumulate this intermediate in much larger amounts than the wild type. The results show that E204Q and E204D give distorted all-trans-retinal chromophore like the O intermediate of the wild type. This is simply due to the perturbation of the proton acceptor function of Glu-204 in the O-to-BR transition in the Glu-204 mutants. The corresponding red-shifted intermediates of L93M, L93T, and L93S have a 13-cis chromophore like the N intermediate of the wild type, as reported from analysis of extracted retinal [Delaney, J. K., Schweiger, U., & Subramaniam, S. (1995) Proc. Natl. Acad. Sci. U.S.A. 92, 11120-11124]. In spite of their different chromophore structures from the O intermediate, the red-shifted intermediates are similar to the O intermediate but not to the N intermediate of the wild type with respect to structural changes in the peptide carbonyls. The structural changes around Asp-96 in the N intermediate are completely restored also in the red-shifted intermediates of the Leu-93 mutants like in the O intermediate. These results imply that the protein structural changes in the last step proceed regardless of thermal isomerization of the chromophore. Time-resolved Fourier transform infrared spectroscopy with the Glu-204 mutants suggests that the response of Asp-204 (Glu-204 in the wild type) to the protonation of Asp-85 during formation of the M intermediate, which results in proton release, is slow and may occur through structural changes.

Bacteriorhodopsins↗
PubMed1997

Swine influenza virus strains recognize sialylsugar chains containing the molecular species of sialic acid predominantly present in the swine tracheal epithelium.

We determined the ratio of N-glycolylneuraminic acid (Neu5Gc) to N-acetylneuraminic acid (Neu5Ac) in swine respiratory epithelia by fluorometric high-performance liquid chromatography, and examined the binding specificity of swine influenza virus strains for gangliosides containing different molecular species of sialic acid (Neu5Ac and Neu5Gc), and for bovine erythrocyte sialoglycoprotein 2 (GP-2) containing Neu5Gc as its predominate sialic acid (96% of total sialic acids). The presence of Neu5Gc, which had not been detected in human tracheal epithelia, and Neu5Ac in swine tracheal epithelia was observed in a 1:1 ratio. The swine influenza virus H1 and H3 isolates tested, except for A/swine/Iowa/15/30 (H1N1), displayed a marked binding ability for sialylsugar chains containing Neu5Gc compared with that of the human influenza virus strains. These results suggest that swine influenza viruses recognize sialylsugar chains containing the molecular species of sialic acid present predominantly in the swine tracheal epithelium.

Animals↗
PubMed1997

Anastomotic intimal hyperplasia: a comparison between conventional and endovascular stent graft techniques.

Endovascular grafts (EVGs) have been proposed as a treatment for a variety of vascular diseases; however, the impact of EVGs on graft healing has not been fully evaluated. The aim of this study is to compare anastomotic intimal hyperplasia (AIH) and endothelialization in EVGs and conventional bypass grafts (CGs). Seven mongrel dogs received an EVG in one iliac artery and a CG in the other iliac artery using a 5 mm x 4 cm polytetrafluoroethylene graft. The EVG was secured to the native vessel wall, with balloon expandable stents at either ends of the graft. CGs were anastomosed using running sutures. Intravascular ultrasound was performed at the time of sacrifice (8 weeks) to determine percentage of stenosis at the distal anastomosis. Specimens were divided longitudinally for light microscopic analysis (thickness of distal AIH) and scanning electron microscopic studies (percentage of endothelial coverage of the graft). Percentage of stenosis at the distal anastomosis was significantly higher in EVGs compared with CGs (28.2 +/- 18.2% versus 1.8 +/- 2.8%; P < 0.01) due to significantly greater mean intimal thickness in the EVGs (441.1 +/- 101.1 microns versus 82.4 +/- 41.9 microns; P < 0.01). The total percentage of area covered by endothelial cells was also significantly greater in EVGs compared with CGs (80.5 +/- 37.5% versus 30.3 +/- 37.1%; P < 0.05). Intraluminal location enhanced endothelialization of the polytetrafluoroethylene graft; however, it also resulted in greater AIH. Further device refinements including stent design may be required to maximize the potential of these endovascular procedures.

Anastomosis, Surgical↗
PubMed1997

Closure of a ventricular septal defect in a patient with von Willebrand disease.

Few reports of open heart surgery being performed in patients with von Willebrand disease (vWD) have been documented. We describe herein the case of a 5-year-old girl with a ventricular septal defect (VSD) and vWD who underwent patch closure under cardiopulmonary bypass (CPB). The hematological parameters relating to vWD, namely, factor VIII, von Willebrand factor, and factor VIII-related antigen were monitored perioperatively. These laboratory findings were elevated after the termination of CPB, and consistently maintained within the normal range for 4 months postoperatively. The operation was successfully completed without the administration of factor VIII concentrates or homologous blood products.

Cardiopulmonary Bypass↗
PubMed1997

Behavioral stimulation without alteration of beta and 5-HT receptors and adenylate cyclase activity in rat brain after chronic sertraline administration.

Effects of chronic treatment with selective 5-HT reuptake inhibitors (SSRIs) on the monoaminergic functions have not been much investigated in compared with tricyclic antidepressants. Therefore, we compared the effects of 3-week treatment with sertraline, a potent SSRI, to those of imipramine (10 mg/kg, IP, twice a day), on monoamine receptors and adenylate cyclase (AC) activity in rat brain. Two-week treatment with both sertraline and imipramine reduced immobility in the water wheel test to the comparable extent. Sertraline treatment did not affect Kd and Bmax of [3H]CGP12177 and [3H]ketanserin bindings or cAMP, accumulation by norepinephrine, isoproternol, 5'-guanylylimidodiphosphate [Gpp(NH)p] and forskolin in the cortical membrane compared with vehicle-treated rats. On the other hand, imipramine treatment decreased Bmax of both bindings and norepinephrine- or isoproternol-stimulated cAMP accumulation. Treatment with either antidepressant induced no apparent changes in [3H]8-OH-DPAT [2-(N, N-dipropylamino)-8-hydroxy-1,2,3,4-tetrahydronaphthalene] binding in the hippocampal membrane. These results suggested that chronic treatment of sertraline induced little effect on monoamine receptors and AC activity in the brain and that the alteration of these functions may not be primarily involved in antidepressive effects of antidepressants, at least of SSRIs.

1-Naphthylamine↗
PubMed1997

The relationship between progression of visual field defects and retrobulbar circulation in patients with glaucoma.

PURPOSE: To investigate whether lower blood flow velocities and higher resistive indices in the retrobulbar arteries are associated with progression of visual field defects in eyes with open-angle glaucoma with or without increased intraocular pressure. METHODS: Color Doppler imaging was performed in 16 eyes with progressive visual field defects in patients with normal-tension glaucoma, 15 eyes with practically stable visual field defects in patients with normal-tension glaucoma, 14 eyes with progressive visual field defects in glaucomatous patients with increased intraocular pressure, and 14 eyes with practically stable visual field defects in glaucomatous patients with increased intraocular pressure. Peak systolic velocity and end-diastolic velocity were measured, and resistive index was calculated in the central retinal artery, short posterior ciliary arteries, and the ophthalmic artery. RESULTS: Eyes with progressive visual field defects in patients with normal-tension glaucoma had statistically significantly lower blood flow velocities and higher resistive index in the central retinal artery and the short posterior ciliary arteries than did those with practically stable visual field defects, whereas, in the glaucomatous patients with increased intraocular pressure, such differences were not found. CONCLUSIONS: Eyes of patients with normal-tension glaucoma and progressive visual field defects have decreased blood flow velocities and increased resistive indices in their retrobulbar arteries, suggesting that these circulatory factors may be associated with the deterioration of visual field defects in patients with normal-tension glaucoma but may be less involved in the deterioration in glaucomatous patients with increased intraocular pressure.

Blood Circulation↗
PubMed1997

An extremely rare variant of congenital jejunoileo-colic atresia.

This report presents an unusual case of a congenital long-segment jejunoileo-colic obstruction without mesenteric or intestinal interruption. Histologically, the intestinal lumen was completely or partially obstructed by fibrous or granulation tissue, and the mucosa had disappeared.

Abnormalities, Multiple↗
PubMed1997

Achievement of a complete cytogenetic response with hydroxyurea in a patient with chronic myelogenous leukemia.

Hydroxyurea rarely produces a complete cytogenetic remission in patients with chronic myelogenous leukemia (CML). In this report, we describe one case of the CML patient who achieved complete cytogenetic remission (no Ph chromosome in 20-25 metaphase cells) by treatment with hydroxyurea alone. By the fluorescent in situ hybridization (FISH) methodology using bcr/abl specific translocation probe, sequential bone marrow specimens from the patient showed the characteristic 9;22 translocation at a higher rate (9-10%) than the normal control range (2.49-4.88%) at the time of complete cytogenetic remission. Thus, it is suggested that FISH is a more sensitive method to detect the bcr/abl fusion gene than conventional cytogenetic analysis for the detection of minimal residual disease in CML.

Antineoplastic Agents↗
PubMed1997

Trajectory formation of the center-of-mass of the arm during reaching movements.

We attempted to identify the invariant kinematic properties of multijoint arm reaching movements in the horizontal plane to explore the planning variable(s) involved in their coordination. Different targets were placed near the perimeter of the workspace boundary, thereby causing variation of size and orientation of the hand stroke. We have a special interest in the trajectory characteristics of the most massive point within the arm system, the center-of-mass of the entire arm system, in addition to those of the hand or joints. The motion of the individual segments (the forearm plus hand and the upper arm) or joints (shoulder and elbow) was modulated in a different way depending on the tasks; thus, there was no invariance in the relationships between paired variables (displacement or velocity) for segment or joint motions. For relatively short hand strokes, the trajectory of the hand and the center-of-mass of the entire arm system were characterized by a nearly straight path, and a smooth, bell-shaped velocity curve along the path, symmetrical about the mid-portion of the movement, starting from nearly zero, growing to a single peak and declining again to nearly zero. However, in large hand strokes the hand path was highly curved and the velocity curve was asymmetric. Although the path of the center-of-mass of the entire arm system also tended to be curved with the increase of the hand stroke, a bell-shaped velocity curve along the path and its typical symmetry were preserved over a wide range of stroke sizes and orientations, and its peak was scaled in proportion to movement distance and movement time. Our findings indicate that it is not valid to postulate solely the joint- or hand-based planning strategies which have been proposed previously. Rather, the planning of the spatial aspects of the motion is largely dependent on the interaction of multiple variables, including those not analysed in this study. The bell-shaped pattern of the center-of-mass velocity profile represents a certain efficiency of movement, since it corresponds to a single accelerative and a decelerative phase of a mass over the movement, with no intermediate force reversals. The simple structure of the center-of-mass velocity profiles may reflect a fundamental organization principle underlying the temporal aspects of movement planning.

Adult↗
PubMed1997

A simulation study of the electromyographic volley at initiation of rapid isometric contractions in the first dorsal interosseous muscle.

Monopolar surface electromyograms (EMGs) of rapid isometric abduction of the first dorsal interosseous muscle (FDI) were initiated from an EMG volley that was characterized by a negative potential lasting over several tens of milliseconds. An EMG model was developed to study how the EMG volley was generated. EMGs were defined as the linear summations of surface-recorded action potential trains originating from single motor units (MUs). All action potential trains had the same discharge pattern but different recruitment thresholds, depending on the potential amplitude. Real action potentials in single MUs in FDI were recorded with a monopolar surface electrode, one of which was used as a prototype wave in simulation. The model predicted an initial negative potential comparable to that of the EMG volley observed in rapid contractions of FDI. Results from our simulation studies suggest that the EMG volley is caused by at least two independent factors: (1) the negative phase of the action potential is greater in area than the positive one, in which the effect is enhanced by the high discharge rate of many MUs; (2) many MUs are recruited within a short time in an orderly fashion starting from those with small action potentials to those with large ones.

Action Potentials↗
PubMed1997

Susceptibility of Helicobacter pylori isolates to metronidazole, clarithromycin and amoxycillin in vitro and in clinical treatment in Japan.

BACKGROUND: Primary and acquired resistance to antibiotics is an important factor in determining the reason for treatment failure in Helicobacter pylori infection. We examined the relationship between the susceptibility of H. pylori isolates and the efficacy of chemotherapy. METHODS: The minimal inhibitory concentrations (MICs) of metronidazole (MNZ), clarithromycin (CLAR) and amoxycillin (AMOX) of 320 H. pylori pre-treatment isolates were determined by the agar dilution method. In 290 patients with peptic ulcers. H. pylori infection was treated by dual or triple combination therapies for 2 weeks: one proton pump inhibitor (30 mg/day lansoprazole or 20 mg/day omeprazole) and one or two antibiotics (500 mg AMOX, 200 mg CLAR or 250 mg MNZ twice a day). MICs were also determined after the treatment failure. RESULTS: Among the drugs tested, for MNZ and CLAR, 8.1% and 9.1% of the isolates, respectively, were resistant, while no isolate was resistant to AMOX. After unsuccessful treatment using MNZ and CLAR, 66.7% and 70.61% of the isolates changed from sensitive to resistant, respectively. All isolates were sensitive to AMOX after treatment failure. CONCLUSIONS: The failure of the H. pylori treatment results in the induction of resistance to CLAR and/or MNZ. Regimens with a high cure rate should be used in order to prevent the generation of acquired resistance to antibiotics.

Adolescent↗
PubMed1997

Intramembrane signaling mediated by hydrogen-bonding of water and carboxyl groups in bacteriorhodopsin and rhodopsin.

The light-induced mechanism for proton pumping of bacteriorhodopsin was studied by Fourier transform infrared spectroscopy of the discrete sequential intermediate states, L, M, and N. Attention is focused on L in the early microsecond time range, as a transition state in which the Schiff base forms strong H-bonding with a water molecule coordinated with Asp85. This structure leads to transfer of the Schiff base proton to Asp85 in the L-to-M process, which then triggers proton release from Glu204 to the extracellular surface. H-bonding of Arg82 and water molecules are involved in this process. Chloride can replace Asp85 in the D85T mutant, and this anion will be then transported instead of a proton. In L, structural perturbations are induced also around Asp96, through a string of H-bonding mediated by internal water molecules and peptide carbonyls in helices B and C, and Trp182 in helix F. These may cause the structural changes that occur later in the M-to-N process. Similar interactions, through internal water molecules and the peptide bonds in helices B and C, take place in bovine rhodopsin. They transduce changes across the membrane from the Schiff base to the cytoplasmic surface, where the activation of the transducin occurs.

Animals↗
PubMed1997

Analysis and typing of the vacA gene from cagA-positive strains of Helicobacter pylori isolated in Japan.

Approximately 50% of Helicobacter pylori strains produce a cytotoxin that is encoded by vacA and that induces vacuolation of eukaryotic cells. Mosaicism in vacA alleles was reported, and there are three different families of vacA signal sequences (s1a, s1b, and s2) and two different families of middle-region alleles (m1 and m2). In addition, the vacA genotype of a strain is associated with its cytotoxin phenotype and its capacity to induce peptic ulceration. To clarify the strain diversity of H. pylori in Japan, 87 Japanese clinical isolates of H. pylori (40 from patients with chronic atrophic gastritis, 25 from patients with duodenal ulcer, 16 from patients with gastric ulcer, 3 from patients with both duodenal and gastric ulcers, and 3 from patients with intestinal type gastric cancer) were characterized by vacA typing by PCR and DNA sequencing. Eighty-four of the 87 isolates were s1a/m1, one was s1b/m1, and two could not be typed. Moreover, all isolates in this study were cagA positive. There were no distinct differences between the cytotoxin-producing strains and cytotoxin-nonproducing strains within the 0.73-kb middle region. Japanese strains were highly homologous, with more than 96% identity in this region, in which maximum divergence has been reported. In addition, there were no associations between the specific vacA types and the level of in vitro cytotoxin activity or the clinical consequences. These results indicate that the cagA-positive, s1a/m1-type strains are common in Japan, regardless of the vacA phenotype or clinical outcome.

Antigens, Bacterial↗