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Biomedical subjects

H Honda

Publications and source records attributed to H Honda.

At least 217 records · Page 12Linked to original sources
PubMed1997

Acetylcholine-induced relaxation of rat aorta is greatest during estrus in the sexual cycle.

Acetylcholine (ACh)-induced relaxation in the aortae precontracted with norepinephrine was significantly enhanced in the aortae from estrus (E) rats, compared with that in those from metestrus (D-1), diestrus (D-2) and proestrus (PE) rats. NG-Nitro-L-arginine methyl ester (L-NAME) inhibited the endothelium-dependent relaxation in E rats. These results suggest that there is a difference in ACh-induced relaxation of the thoracic aorta during the sexual cycle of rats, and the relaxation is greatest in E of the sexual cycle; this may be due to a difference in nitric oxide synthesis in the endothelium in the sexual cycle.

Acetylcholine↗
PubMed1997

Most probable numbers of enterotoxigenic Clostridium perfringens in intestinal contents of domestic livestock detected by nested PCR.

The incidence and numbers of enterotoxigenic Clostridium perfringens in the intestinal contents of cattle, swine and broiler chickens were determined and compared with those of total (enterotoxigenic and nonenterotoxigenic) C. perfringens. The method used for the enumeration of enterotoxigenic C. perfringens consisted of a combination of the most probable number (MPN) method and a nested polymerase chain reaction after enrichment culture of the sample. Enterotoxigenic C. perfringens was found in 26% (4.0 x 10-4.3 x 10(2) MPN/100 g), 22% (4.0 x 10-2.3 x 10(3) MPN/100 g) and 40% (4.0 x 10-2.4 x 10(4) MPN/100 g) of intestinal contents of 50 head each of cattle, swine and broiler chickens, respectively. Whereas, total C. perfringens was found in 76% (9.0 x 10-7.5 x 10(6) MPN/100 g), 44% (7.0 x 10-4.3 x 10(6) MPN/100 g) and 80% (4.3 x 10(2)-9.3 x 10(7) MPN/100 g) of intestinal contents of 50 head each of cattle, swine and broiler chickens, respectively, by the conventional MPN method. In all cases, enterotoxigenic cells were not dominant in the population of C. perfringens: a small number of enterotoxigenic cells of C. perfringens co-existed with a large number of nonenterotoxigenic cells in the same sample. The ratios of enterotoxigenic C. perfringens cells to total C. perfringens cells were 1/10-1/10(5).

Animals↗
PubMed1997

Anatomy and clinical importance of cholecystic venous drainage: helical CT observations during injection of contrast medium into the cholecystic artery.

OBJECTIVE: The purpose of this study was to use helical CT to elucidate the anatomy and clinical importance of cholecystic venous drainage. SUBJECTS AND METHODS: We performed helical CT of the upper abdomen during injection of contrast medium through a superselectively catheterized cholecystic artery (cholecystic artery CT) in 28 patients, all of whom were surgical candidates for suspected hepatobiliary abnormality. In nine of these patients, CT during arterial portography (CTAP) was also performed. RESULTS: Cholecystic venous blood most frequently entered peripheral portal branches of hepatic segment V (27 of 28 patients, 96%) and segment IV (26 of 28, 93%). In order of decreasing frequency, cholecystic venous blood also drained to segments I, VI, VIII, III, and VII. Cholecystic venous blood subsequently drained into the middle hepatic vein (21 of 28, 75%) or right hepatic vein (20 of 28, 71%). In two patients with adenocarcinoma involving the gallbladder associated with multiple liver metastases, cholecystic venous drainage was seen around each metastatic focus. In the nine patients in whom both cholecystic artery CT and CTAP were performed, nontumorous portal perfusion defects were attributable to cholecystic venous drainage. CONCLUSION: Recognition of cholecystic venous drainage as a possible pathway for spread of disease from the gallbladder to the liver and also as one of the causes of non-tumorous portal perfusion defects seen on CTAP is important.

Aged↗
PubMed1997

Branch geometry in Cornus kousa (Cornaceae): computer simulations.

Computer simulations similar to actual trees were constructed using simple branching rules. Branch orientation with respect to the direction of gravity was a fundamental consideration. In Cornus kousa BUERG. ex HANCE, several types of branches develop from winter buds, varying from orthotropic shoots to plagiotropic ones. Based on actual observations and measurements of branching structures with a wide range of orientations, we made a flexible geometrical model consisting of five forking branches that varied in outgrowth depending on the direction of the shoot with respect to gravity. Repetition of the branching by computer generated a realistic tree pattern, which was close to the shape of a young C. kousa tree. Reproductive shoots seem to be under a branching rule that was a modification of vegetative branching, although the reproductive branch size was considerably smaller than the vegetative one, and reproductive branching was bifurcated instead of five-forked. We conclude that all branchings in orthotropic and plagiotropic shoots in the vegetative phase and shoots in the reproductive phase are formed under the same branching rule, but each has different parameter values.

Computer Simulation↗
PubMed1997

Xanthogranulomatous cholecystitis versus gallbladder cancer: clinical differentiating factors.

Xanthogranulomatous cholecystitis (XC) is occasionally difficult to differentiate from gallbladder cancer and mandates efforts to avoid extensive operations. We studied the clinical factors to differentiate XC from cancer. Subjects were a consecutive series of 10 patients with XC and 10 with carcinoma, all of whom radiologically showed thickened gallbladder walls. As opposed to cancer, XC was typified by invisible gallbladders on cholangiography (1), the presence of cholelithiasis (P = 0.01) (2), and, intraoperatively, an aspirate of pus or nothing (P < 0.01) (3). To diagnose XC against gallbladder cancer, (1) and (2) in combination and (3) demonstrated an accuracy of 82.4% and 85.0 per cent, respectively. Clinically, XC can be distinguished from gallbladder cancer by cholangiography, calculous findings, and a gallbladder aspirate of pus or nothing.

Aged↗
PubMed1997

[Early HCC and adenomatous hyperplasia: evaluation of arterial and portal blood flow with CTA, CTAP, and pathologic correlation].

In order to analyze the hemodynamic properties of early hepatocellular carcinoma (HCC) and adenomatous hyperplasia (AH), three lesions (two HCCs, one AH) depicted as hypoattenuating at CTA and iso attenuating at CTAP were correlated with the histopathological findings. The number of normal hepatic arteries in the tumor was lower than in the liver. Degeneration and narrowing of the lumens were also seen microscopically. All tumors showed the replacing growth pattern and had similar numbers of the portal tracts in the tumor to the liver. The decreased number of intratumoral normal arteries is suspected to be a characteristic finding of the early stage of HCC.

Adenoma↗
PubMed1996

Plasma vanillylmandelic acid level as an index of psychological stress response in normal subjects.

The relationships between psychological stress responses and plasma levels of vanillylmandelic acid (VMA), 3-methoxy-4-hydroxyphenylglycol (MHPG), homovanillic acid (HVA), and 5-hydroxyindolacetic acid (5-HIAA) were investigated in normal volunteers. Two questionnaires were used to measure stress: the Psychological Stress Response Scale (PSRS) and the State-Trait Anxiety Inventory (STAI). Plasma levels of VMA--but not MHPG, HVA, and 5-HIAA--showed significant positive correlations with PSRS emotional and cognitive-behavioral stress and STAI state anxiety. Significant positive correlations were also found between plasma levels of VMA and MHPG and psychological stress responses measured repeatedly in a longitudinal study of an Olympic swimmer. Plasma VMA measurements, which reflect the level of activity of the peripheral sympathetic nervous system, may provide a useful biochemical index of psychological stress responses in normal subjects.

Adult↗
PubMed1996

Cloning and characterization of mouse tec promoter.

Tec is a cytoplasmic protein-tyrosine kinase highly expressed in hematopoietic precursor cells. To investigate the mechanism regulating its expression, we cloned and characterized the mouse tec promoter. The promoter region does not contain the authentic TATA or CAAT box but has several consensus binding motifs for GATA and SP1. The nucleotide sequence surrounding the major transcription initiation site determined 5' RACE-PCR appeared to be homologous to the "initiator" consensus sequence which is frequently found in genes lacking TATA and CAAT. The promoter activity of the 5' flanking region was confirmed by using the luciferase assay. The present analysis will provide insights into the mechanism for the expression and regulation of the Tec molecule.

3T3 Cells↗
PubMed1996

Communicative interaction of myosins along an actin filament in the presence of ATP.

Myosin molecules contacting an actin filament in the presence of ATP were found to regulate the filamental fluctuations due to ATP hydrolysis in a communicative manner along the filament. As an evidence of the occurrence of the communication, ATP-activated fluctuating displacements of the filament in the direction perpendicular to its longitudinal axis were identified to propagate at a finite velocity not less than about 0.2 micron/s unidirectionally along the filament.

Actin Cytoskeleton↗
PubMed1996

Sharp Increase in the Incidence of Mammary Carcinoma in Kagoshima Prefecture, Japan.

Between 1986 and 1990, among a female population of about 0.95 million, 1184 women living in Kagoshima Prefecture were diagnosed pathologically as having mammary carcinoma. The number of patients with mammary carcinoma, the crude incidence rate per 100000 women and age-standardized mammary carcinoma incidence rates were 205, 21.29 and 19.42 in 1986, 212, 22.04 and 19.48 in 1987, 238, 24.74 and 21.8 in 1988, 245, 25.47 and 22.33 in 1989 and 284, 29.57 and 25.69 in 1990, respectively. The number of patients with this disease increased annually. The increase in the age-specific incidence rate of this type of cancer between 1986 and 1990 was 1.38-fold in women between 40 and 49 years of age, 1.46-fold in women between 50 and 59, 1.37-fold in the 60-69 age group, 1.48-fold in the 70-79 age group and 1.91-fold in women over 80. In both the urban and rural areas, the incidence increased annually during the course of this study. In 1990, the age-standardized mammary carcinoma incidence rate in urban area was 1.17 times that in rural area.

Journal Article↗
PubMed1996

Dual role of tropomyosin on chemically modified actin filaments from skeletal muscle.

Actin filaments copolymerized with both intact and chemically modified actin monomers restored their sliding activity when they were supplemented with tropomyosin extracted from skeletal muscle. In contrast, the ATPase activation of the copolymers was decreased when supplemented with tropomyosin. The results indicate that tropomyosin along with actin monomers may facilitate sliding activity of the entire actin filament but suppress ATPase activation of intact actin monomers themselves. Accordingly, tropomyosin molecules could be viewed as playing a dual role of both mechanical and chemical regulation of actin monomers.

Actin Cytoskeleton↗
PubMed1996

ATP-dependent fluctuations of single actin filaments in vitro.

Single filaments of actin were observed to fluctuate in the direction perpendicular to their longitudinal axes when they hydrolyzed ATP in the presence of myosin. The transversal fluctuations of actin filaments were identified by reading the transversal displacements of the filaments under a fluorescence microscope. The transversal fluctuations in the absence of ATP decreased their intensity as the number of myosin molecules contacting directly with actin filaments increased. In the presence of ATP, on the other hand, the amplitude of the transversal fluctuations increased in proportion to the ATP concentration up to a certain level, while the sliding velocity of the filaments did not increase significantly over the same range of ATP concentration. The present observation suggests that the chemical energy released from ATP along actin filament binding to myosin molecules is first and primarily converted into kinetic energy of fluctuations in the form of the displacement movements of the filaments in the direction perpendicular to their longitudinal axes.

Actins↗
PubMed1996

Theoretical treatment of striated muscle: Dynamic extension of four-state model.

We constructed a muscle model, based on the model first proposed by Gray and Gonda [6,7), that simulates the twitch contraction of striated muscle. Their original model postulated four basic states in the contraction cycle and predicted the properties of steady state contraction in striated muscle. Using the relationship between steady state tension and calcium concentration, we described several rate constants as functions of calcium concentration and calculated the number of attached crossbridges at various calcium concentration values. The results for both skeletal and cardiac muscle were approximately consistent with those of X-ray studies. Assuming that rate constants change immediately with the phasic alteration of intracellular calcium concentration, we estimated the time course of crossbridge distribution during twitch contraction; these findings were also consistent with those of X-ray studies. We also simulated the effects of calcium concentration and sarcomere length on the magnitude of twitch tension. These simulations suggest that the major determinants of crossbridge distribution during twitch contraction are the time courses of calcium transients and the rate constants of crossbridge kinetics. Our findings suggest that the model used in this study provides a theoretical basis for interpreting the characteristics of cardiac muscle encountered in the clinical setting.

Animals↗
PubMed1996

Cross-bridge movement in rat slow skeletal muscle as a function of calcium concentration.

A single fibre bundle from rat soleus muscle was chemically skinned with saponin and the transfer of myosin heads from the thick filaments to the thin filaments at a sarcomere length of 2.4 microm was measured as a function of Ca2+ concentration using an x-ray diffraction method at 4-7 degrees C. In the relaxed state, the 1,0 spacing was 42.08 nm. The spacing showed no significant decrease when the Ca2+ concentration was below the threshold (-log10 [Ca2+] or pCa 5.8). No significant transfer of the myosin heads occurred when the Ca2+concentration was below the threshold (pCa 5.8). When the muscle was maximally activated at pCa 4.4, the spacing decreased to 40.35 nm. During the maximum isometric contraction at pCa 4.4, 54. 9 +/- 6.5% (+/-SE of the mean) of the myosin heads were transferred to the thin filaments. The transfer of the myosin heads was approximately proportional to relative tension. These results suggest that myosin heads of both fast-twitch and slow-twitch skeletal muscles transferred on the common movement as a function of Ca2+ concentration.

Actins↗
PubMed1996

The effect of diastolic vibration on the relaxation of rat papillary muscle.

OBJECTIVE: It has been demonstrated that the application of an external mechanical vibration during the ventricular relaxation phase of the heart (diastolic vibration) decreases the time needed for myocardial relaxation. The objective of this study is to see whether this vibration-induced decrease in relaxation time is an intrinsic property of the contractile proteins. We hypothesize that this decrease in duration of the late systolic phase by diastolic vibration is likely to be due to a forced detachment of crossbridges from the actin filament. This would then result in a decrease in the relaxation time of myocardial tissue. METHODS: A controlled vibration of variable amplitude and frequency was applied to isolated twitching rat papillary muscles. Vibration was initiated from directly after peak tension development and ended when tension had returned to baseline. Effects of applied vibration were expressed as changes in the time interval from 90% rising- to 50% falling-force level, which was termed the 'late systolic phase'. RESULTS: The data showed that in general diastolic vibration decreased the duration of this late systolic phase. A vibration of 1.0% of Lmax at 50 Hz in the late systolic phase shortened this period by 27 ms (20-30%) on average. At increasing amplitude of vibration the increase in the rate of relaxation was even more pronounced. Shortening of this duration was slightly less at frequencies of vibration below 40 Hz than at higher frequencies of vibration. Changes in the resting muscle length did not result in significant changes in shortening of the studied relaxation period. CONCLUSION: The results show that relaxation is accelerated during application of an external vibration during the period of tension fall of an isolated cardiac muscle preparation. Therefore, we can conclude that the acceleration of relaxation due to vibration is primarily due to properties of the myocytes themselves rather than to the complex geometric structure of the heart. Tension in the relaxation phase was reduced during diastolic vibration, which suggests that the number of crossbridges bound to the actin filament was reduced by the length perturbation.

Animals↗
PubMed1996

Comparison of endothelium-derived relaxing factor activity between nonpregnant and pregnant rats.

The tension of isolated ring preparation of aorta from nonpregnant and pregnant rats was measured isometrically to study the effect of pregnancy on endothelium-derived relaxing factor activity. Contraction in response to norepinephrine and potassium chloride was greater in aortae from nonpregnant rats than in those from pregnant rats. The endothelium-dependent relaxation that was caused by acetylcholine (10(-10)-3 x 10(-9) M) in aortae precontracted with norepinephrine was significantly enhanced in aortae from pregnant rats compared with the relaxation in those from nonpregnant rats. NG-nitro-L-arginine methyl ester (L-NAME) inhibited the endothelium-dependent relaxation in both aorta from pregnant and nonpregnant rats. L-Arginine reversed the inhibition of L-NAME. Those results suggest that the enhanced endothelium-derived relaxing factor activity in rats aortae is associated with pregnancy.

Ammonium Chloride↗
PubMed1996

Isolation of a cDNA for a phosphoenolpyruvate carboxylase from a monocot CAM-plant, Aloe arborescens: structure and its gene expression.

A phosphoenolpyruvate carboxylase (PEPCase) cDNA was isolated from Aloe arborescens, a monocot CAM plant. Northern analysis of the PEPCase transcript indicated that it is specifically expressed in green leaves, strongly suggesting its involvement in CAM photosynthesis. No diurnal change in expression level was evident. Western blot analysis also showed no alteration of the amount of the PEPCase protein. These results suggest that circadian rhythm in PEPCase activity may be regulated post-translationally. The representative cDNA clone contained an ORF encoding 964 amino acid residues. Deduced amino acid sequence of the aloe PEPCase is highly conserved as compared with other PEPCases. The phosphorylation site which may be modified by PEPC-kinase was conserved. An evolutional map with known PEPCases suggested that CAM-type PEPCases were located between C4 and housekeeping PEPCases.

Aloe↗