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Biomedical subjects

Y Hosoya

Publications and source records attributed to Y Hosoya.

At least 91 records · Page 5Linked to original sources
PubMed1994

Tissue-specific mutational spectra of 2-amino-3,4-dimethylimidazo[4,5-f]quinoline in the liver and bone marrow of lacI transgenic mice.

2-Amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ) is a food-borne heterocyclic amine, so clarification of its mutational spectrum is important for evaluation of its carcinogenic risk to humans. The mutational spectrum of MeIQ was investigated in the liver and bone marrow of transgenic mice carrying the lacI gene. By PCR--single-strand conformation polymorphism analysis and sequencing of the lacI gene, 81 and 61 mutations were identified in 80 and 59 mutants obtained from the liver and bone marrow respectively of three transgenic mice given food containing 300 p.p.m. MeIQ. In the liver, G-->T transversions were the most frequent, accounting for 46% of the total mutations, followed by G-->A transitions (25%). In the bone marrow, four types of mutations, G-->T transversions, G-->A transitions, complex mutations and one base deletions, each accounted for 21-23% of the total mutations. Of the total mutations, 10% were found at nucleotide 92 in the liver and at nucleotide 222 in the bone marrow. Analysis of 27 and 13 mutants from the liver and bone marrow respectively of control mice showed frequent G-->A transitions at CpG sites. These findings suggest a tissue-specific mechanism of mutagenesis.

Animals↗
PubMed1994

Resin adhesion to the ground young permanent enamel: influence of etching times and thermal cycling test.

The purpose of this study was to investigate the influence of etching times and thermal cycling test on resin adhesion on ground young permanent enamel. Two hundred and fifty bovine mandibular young permanent incisors were used. Materials used in this study were 40 phospholic acid gel, Photo Bond and Photo Clearfil A (Kuraray Co., Kurashiki, Japan) in the PCA groups and 37% phospholic acid gel, Scotch Bond and Silux (3M Co., St. Paul, MN) in the Silux groups. The etching times were 0, 10, 20, 30, and 60 seconds. Shear bond strengths were tested. After the shear bond strength test, the test surfaces of the enamel and the resin specimens were observed using the SEM. The etching times that showed the highest bond strengths were 60 seconds both in the Silux non-thermal cycled group (45.21 +/- 8.49 MPa) and the Silux thermal cycled group (33.40 +/- 5.75 MPa), and 20 seconds in the Silux non-thermal cycled group (35.25 +/- 6.60 MPa) and 30 seconds in the PCA thermal cycled group (45.21 +/- 8.49 MPa). In the PCA groups, the bond strengths were significantly increased by thermal cycling tests, however, in the Silux groups, the bond strengths were significantly decreased by thermal cycling tests.

Acid Etching, Dental↗
PubMed1993

GK* and brain G beta gamma activate muscarinic K+ channel through the same mechanism.

A pertussis toxin-sensitive G protein (GK) links muscarinic cholinergic and A1-purinergic receptors with an inwardly rectifying K+ (KACh) channel in cardiac atrial cell membranes. Although the beta gamma subunits of pertussis toxin-sensitive G proteins (G beta gamma) have been reported to fully activate this channel, it is not known whether exogenously applied G beta gamma interacts with the KACh channel through the same mechanism as the active subunit of endogenous GK (GK*). We examined in inside-out patches the relationship between the concentration of GTP and KACh channel activity with or without preactivation of the channels by either GTP gamma S (guanosine 5'-3-O-(thio)triphosphate) or G beta gamma purified from bovine brain. In the control, KACh channels were activated by intracellular GTP (with acetylcholine in the pipette) in a positive cooperative manner (Hill coefficient approximately 2.5). As the channels were preactivated by GTP gamma S to progressively higher levels, the GTP channel activity relationship shifted more to the left, but the Hill coefficients of the curves remained the same. The same changes were observed when KACh channels were preactivated with brain G beta gamma. These results indicate that endogenous GK* and exogenous G beta gamma share a common molecular mechanism to activate the KACh channel.

Animals↗
PubMed1993

Quantitative analysis of central terminal projections of visceral and somatic unmyelinated (C) primary afferent fibers in the guinea pig.

In guinea pigs, intracellular labeling of the dorsal root ganglion (DRG) cells with Phaseolus vulgaris-leucoagglutinin (PHA-L) was used to demonstrate the central projections of somatic and visceral afferent C-fibers. The terminations of the afferent fibers were analyzed qualitatively and quantitatively with the aid of camera lucida drawings. Terminal branches of C-fibers of both somatic and visceral origin were, in general, distributed in accord with the organization of the neuropil in lamina of the spinal cord. Terminal boutons arranged from longitudinally coursing fibers were distributed in lamina I, while boutons in lamina II were scattered in an apparent random fashion. The synaptic enlargements were counted in gray matter of the spinal dorsal horn and measured on each terminal branch of a fiber. All synaptic boutons (over one thousand) of somatic fibers were found in the superficial dorsal horn (laminae I and II). More than 60% of the synaptic enlargements of the visceral afferents also were localized superficially (lamina I and adjacent dorsal funiculus) while 10-20% of the visceral enlargements appeared in deeper layers of the spinal cord. Boutons of somatic C-fibers were larger than those of visceral origin. Quantitative data of the unmyelinated afferent fibers are discussed in the context of the sensory functions of myelinated afferent fibers.

Animals↗
PubMed1993

Role of ATP-sensitive K+ channel on ECG ST segment elevation during a bout of myocardial ischemia. A study on epicardial mapping in dogs.

BACKGROUND: ATP-sensitive K+ channels are activated when the myocardium becomes ischemic. However, the role of the ATP-sensitive K+ current in the emergence of ECG ST changes during ischemia remained unclarified. METHODS AND RESULTS: The left anterior descending coronary artery (LAD) was cannulated and perfused with arterial blood from the carotid artery through a bypass tube in 8 anesthetized, open-chest dogs. An array of 60 unipolar electrodes mounted on a sock was used to record epicardial electrograms of the whole heart. Pinacidil (10 micrograms.kg-1 x min-1), an ATP-sensitive K+ channel opener, was infused into the bypass tube for 2 minutes, and the electrograms were recorded before and after the infusion. The elevation of the ST segment and the increase of QRST area were observed spatially over the LAD-perfused region. At the electrode showing the largest ST segment elevation, the activation recovery interval, an index of action potential duration, was shortened from 202 +/- 9 to 111 +/- 18 milliseconds (P < .001). These electrographic changes were similar to those noted in 2-minute coronary occlusion (n = 8). The extent of ST segment elevation during coronary occlusion was attenuated after the intravenous pretreatment with glibenclamide (0.3 mg/kg), a blocker of the KATP channel (n = 5). CONCLUSIONS: The findings of this study suggest that the activation of ATP-sensitive K+ channels during a bout of acute myocardial ischemia plays an important role in the emergence of ECG ST elevation.

Action Potentials↗
PubMed1992

Morphology of sympathetic preganglionic neurons innervating the superior cervical ganglion in the chicken: an immunohistochemical study using retrograde labeling of cholera toxin subunit B.

Preganglionic sympathetic neurons (SPNs) in the chicken were demonstrated immunohistochemically using cholera toxin subunit B (CTb) as a retrograde tracer. After injection of CTb-solution into the superior cervical ganglion, labeled SPNs were mainly found in the ipsilateral sympathetic preganglionic column of Terni (the column of Terni), with only a few in the intermediate zone. They were observed from the caudal half of the 15th cervical segment to the rostral tip of the 3rd thoracic segment. Cell somata of SPNs were loosely packed within the column of Terni, where they had an elliptic shape with the long axis oriented rostrocaudally. In the horizontal plane three kinds of dendrites could be discriminated on the basis of their orientation. Longitudinally oriented dendrites emanated from the rostral and the caudal poles of the SPNs. Medially oriented dendrites were observed to cross the midline and enter the contralateral column of Terni, where they further branched to form a loose dendritic plexus; some extended beyond the lateral limit of the contralateral column of Terni to reach the intermediate zone. Laterally oriented dendrites formed periodically arranged dendritic bundles projecting into the intermediate zone. The present findings provide a detailed account of the dendritic organization of SPNs in the chicken, and suggest that avian SPNs share certain structural features in common with mammalian SPNs.

Animals↗
PubMed1992

Relation between recovery sequence estimated from body surface potentials and T wave shape in patients with negative T waves and normal subjects.

BACKGROUND: Advances in analytical methods of the epicardial electrical potentials allowed us to demonstrate spatial distributions of local recovery. Because local recovery will be reflected in events on body surface ECG mapping, abnormalities in recovery sequence that may be responsible for the origin of negative T waves can be detected from body surface potentials. METHODS AND RESULTS: Eighty-seven unipolar ECGs were recorded simultaneously from the entire thorax in patients having negative T waves on left anterior precordial leads and in normal subjects. These included 40 patients with anterior myocardial infarction (MI), 21 patients with left ventricular hypertrophy (LVH), and 44 male volunteers. We measured Tmax time, defined as the instant of maximal first derivative of the T wave as the index of local recovery (Wyatt's method). Parameters related to T wave potentials were positive T wave amplitude, negative T wave amplitude, and T integral. Significant correlations were observed between the Tmax time and each of the T wave potentials. The T wave potentials were dependent on Tmax times. In the anterior MI, the late Tmax times were located on the upper left anterior chest and early Tmax times on the lower right lateral chest. In the LVH, the area showing a delayed recovery was displaced in a left downward direction compared with anterior MI. CONCLUSIONS: Body surface Tmax time distributions clearly separate two negative T wave groups, i.e., anterior MI and LVH. Appearance of the negative T waves correlates well with the presence of the area with delayed Tmax time on the spatial distribution.

Adult↗
PubMed1992

Spectral analysis of 87-lead body surface signal-averaged ECGs in patients with previous anterior myocardial infarction as a marker of ventricular tachycardia.

BACKGROUND: There were few studies on the relation between the body surface distribution of high- and low-frequency components within the QRS complex and ventricular tachycardia (VT). METHODS AND RESULTS: Eighty-seven signal-averaged ECGs were obtained from 30 normal subjects (N group) and 30 patients with previous anterior myocardial infarction (MI) with VT (MI-VT[+] group, n = 10) or without VT (MI-VT[-] group, n = 20). The onset and offset of the QRS complex were determined from 87-lead root mean square values computed from the averaged (but not filtered) ECG waveforms. Fast Fourier transform analysis was performed on signal-averaged ECG. The resulting Fourier coefficients were attenuated by use of the transfer function, and then inverse transform was done with five frequency ranges (0-25, 25-40, 40-80, 80-150, and 150-250 Hz). From the QRS onset to the QRS offset, the time integration of the absolute value of reconstructed waveforms was calculated for each of the five frequency ranges. The body surface distributions of these areas were expressed as QRS area maps. The maximal values of QRS area maps were compared among the three groups. In the frequency ranges of 0-25 and 150-250 Hz, there were no significant differences in the maximal values among these three groups. Both MI groups had significantly smaller maximal values of QRS area maps in the frequency ranges of 25-40 and 40-80 Hz compared with the N group. The MI-VT(+) group had significantly smaller maximal values in the frequency ranges of 40-80 and 80-150 Hz than the MI-VT(-) group. These three groups were clearly differentiated by the maximal values of the 40-80-Hz QRS area map. CONCLUSIONS: It was suggested that the maximal value of the 40-80-Hz QRS area map was a new marker for VT after anterior MI.

Electrocardiography↗
PubMed1992

Dipyridamole electrocardiography test for the assessment of the severity of coronary artery disease.

The purpose of this study was to investigate the relationship of dipyridamole-induced ST changes to the severity of coronary artery disease. The subjects were 100 patients without myocardial infarction who underwent coronary arteriography for the diagnosis of coronary artery disease. The dipyridamole injection test (D) (0.568 mg/kg/4 min), and symptom-limited treadmill exercise test (T) were performed separately. Body surface electrocardiographic mapping of 87 leads was performed in both tests. The incidences of significant ST depression greater than or equal to 0.10 mV, number of leads showing significant ST depression (nST) and the maximal voltage of ST depression (maxST) in D and T were compared to the number of diseased coronary arteries. In patients without significant coronary stenosis (0VD group), the incidence of ST depression in the dipyridamole test was significantly lower than that in the treadmill test (D 9% vs T 47%, p less than 0.01). While, in one vessel disease (1VD), two vessel disease (2VD), and three vessel disease (3VD) groups, there was no significant difference in the incidence of ST depression between the dipyridamole test and the treadmill test (in 1VD, D 44% vs. T 65%; in 2VD, D 67% vs. T 93%; and in 3VD, D 93% vs. T 96%). In the dipyridamole test, nST was 0.6 +/- 2.4 in 0VD, 4.5 +/- 6.9 in 1VD, 4.1 +/- 4.5 in 2VD, and 10.6 +/- 8.1 in 3VD. Significant differences were found between 0VD and 1VD (P less than 0.05), 0VD and 3VD (P less than 0.01), 1VD and 3VD (P less than 0.01), and 2VD and 3VD (p less than 0.01). The maxST in the dipyridamole test was 0.02 +/- 0.04 mV in 0VD, 0.10 +/- 0.12 mV in 1VD, 0.13 +/- 0.11 mV in 2VD, and 0.22 +/- 0.11 mV in 3VD. Significant differences were found between 0VD and 1VD (p less than 0.01), 0VD and 2VD (p less than 0.01), 0VD and 3VD (p less than 0.01), 1VD and 3VD (p less than 0.01), and 2VD and 3VD (P less than 0.01). For the diagnosis of 3VD, the dipyridamole ECG test had as high a sensitivity (93% vs 96%), higher specificity (68% vs 38%, p less than 0.01), and higher predictive accuracy (75% vs 54%, p less than 0.01) than the treadmill test.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1992

Dipyridamole electrocardiography test for the detection of severe coronary artery stenoses.

To investigate the relationship between dipyridamole-induced ST depression and the severity of coronary artery stenosis, the dipyridamole injection test (D) at 0.568 mg/kg/4 min, and the symptom limited treadmill exercise test (T) were performed separately in 16 normal volunteers and 167 patients who underwent coronary arteriography [91 patients without myocardial infarction (non-MI group) and 76 patients with previous myocardial infarction (MI group)]. Standard 12-lead electrocardiogram and body surface mapping of 87 leads were recorded in both tests. None of the normal volunteers had significant ST depression (greater than or equal to 0.10 mV) in D or T. Regarding the non-MI group, D had as high an incidence of ST depression as T (83% vs 93%) in patients with maximal coronary stenosis greater than or equal to 90%, while in those with maximum coronary stenosis less than 90%, D had a lower incidence of ST depression than T (16% vs 48%, p less than 0.01). For the MI group, the incidence of ST depression was compared to the maximal coronary artery stenosis supplying the non-infarcted area. In patients with maximal coronary artery stenosis greater than or equal to 90%, D had as high an incidence of ST depression as T (71% vs 64%). While, D had a lower incidence of ST depression than T (19% vs 35%, p less than 0.05) in those with maximum coronary artery stenosis less than 90%. For the diagnosis of coronary artery stenosis of greater than or equal to 90%, D had as high sensitivity (non-MI group, 82% vs 93%; MI group, 71% vs 64%) and higher specificity (non-MI group, 84% vs 52%, p less than 0.01; MI group, 81% vs 65%, p less than 0.05) compared with T. This study demonstrated that dipyridamole ECG is a sensitive and specific test to detect severe coronary artery stenosis.

Adult↗
PubMed1992

[Prophylaxis of superficial bladder tumor with the intravesical instillation of bacillus Calmette-Guerin or anti-cancer agents. A retrospective study].

It was retrospectively analyzed whether intravesical instillation of bacillus Calmette-Guerin (BCG) or anti-cancer agents had prophylactic effect or not after removal of superficial bladder tumors. The results over a follow-up period ranging from 6 to 40 months showed 23.8 per cent recurrence in group 1 patients treated with BCG (21 patients), 46.7 per cent recurrence in group 2 treated with anti-cancer agents (45 patients) and 52.3 per cent recurrence in the group 3 (127 patients) which were not received any intravesical drugs. Long-term results among the 3 groups calculated with Kaplan-Meier method demonstrated that the instillation of BCG or of anti-cancer agents was more useful for prophylaxis, compared with the actuarial non-recurrence rates of group 3. The instillation of BCG showed good prophylactic effects especially in recurrent, grade 2 and pTa bladder tumors. The instillation of anti-cancer agents showed to provide prolonged protection from recurrence, but the instillation of BCG did not.

Administration, Intravesical↗
PubMed1992

[Radiopacity of the cystine calculi on KUB].

To study the radiopacity of cystine calculi. We have compared them with oxalate and/or phosphate calculi on plain X-ray films (KUB). Eleven pure cystine calculi from 5 people in 4 families, and 8 oxalate and/or phosphate calculi as controls were obtained from patients by lithotomy or spontaneous discharge in Dokkyo University School of Medicine and affiliated hospitals, since 1978. The radiopacity of cystine calculi was measured by a densitometer PDA-60 (Konika Co.), comparing the density of the calculus with that of the area surrounding the calculus on KUB. All cystine calculi were easily recognized on KUB, and their densities were fairly identical with those of oxalate and/or phosphate calculi.

Adult↗
PubMed1992

Resin adhesion to the ground primary enamel: influence of etching times and thermal cycling test.

The purpose of this study was to investigate the influence of etching times and thermal cycling on resin adhesion on ground primary enamel. Two hundred bovine mandibular primary incisors were used. Materials used in this study were 40% phospholic acid gel, Photo Bond and Photo Clearfil A (Kuraray Co., Kurashiki, Japan) in PCA groups and 37% phospholic acid gel, Scotch Bond and Silux (3M Co., St. Paul, MN) in the Silux groups. The etching times were 0, 10, 20, 30 and 60 seconds. Shear bond strengths were tested. After the shear bond strength test, the test surfaces of the enamel and the resin specimens were observed using the SEM. The etching times that showed the highest bond strengths were 30 seconds both in the PCA non-thermal cycled group (80.10 +/- 13.01 MPa) and the PCA thermal cycled group (78.99 +/- 10.93 MPa), 20 seconds in the Silux non-thermal cycled group (76.77 +/- 12.99 MPa) and 60 seconds in the Silux thermal cycled group (63.61 +/- 19.64 MPa). The influence of thermal cycling test to the enamel-resin adhesion is relatively slight both in the PCA group and the Silux group.

Acid Etching, Dental↗
PubMed1992

[A bladder cancer with complete remission after arterial infusion of anti-cancer agents (CDDP and THP) and balloon-catheter occlusion of the internal iliac artery: a case report].

The case was a 63-year-old male with the chief complaint of hematuria. A local doctor made the diagnosis of a bladder tumor (egg-sized) on the basis of the results of ultrasonography. CT-scan and cystoscopy. He was thus referred to our Department for treatment. Histopathological study of the biopsied tumor specimen revealed that the tumor was a squamous cell carcinoma. The bilateral internal iliac arteries were occluded for 48 hours, and 100 mg of CDDP and 40 mg of THP were arterially infused. After 7 days, hematuria disappeared, as did the tumor 5 weeks after treatment. No malignancy was noted from histological examination of a biopsy specimen obtained from the cured cancer region using a cystoscope. Since then, there was no recurrence for 12 months. Thus, this approach is thought to be an effective treatment for primary bladder cancer.

Antineoplastic Combined Chemotherapy Protocols↗