Biomedical subjects

H Iwata

Publications and source records attributed to H Iwata.

At least 271 records · Page 15Linked to original sources

PubMed1998

Expression and characterization of dog CYP2D15 using baculovirus expression system.

Dog CYP2D15 was expressed in Sf9 cells with a recombinant baculovirus. Infection of Sf9 insect cells with a recombinant dog CYP2D15-virus resulted in the expression of a protein which cross-reacted with a polyclonal antibody against a dog CYP2D15-specific peptide. The difference spectrum of CO-complex of reduced P450 of the infected cell microsomes had a maximal absorbance at 449 nm. The specific content of P450 was calculated to be 0.56 nmol/mg of Sf9 cell microsomal protein. Although the expressed dog CYP2D15 showed high catalytic activity for the hydroxylations of bunitrolol and imipramine at low substrate concentration (10 microM), the catalytic activity for that of debrisoquine (50 microM) was extremely low as compared with that of CYP2D from other species. Dog liver microsomes also showed bunitrolol and imipramine hydroxylase activities, but not debrisoquine hydroxylase activity at the same substrate concentrations. In addition, the expressed CYP2D showed high catalytic activity for imipramine N-demethylation. Thus, our study reveals that the expressed dog CYP2D15 engages in high catalytic activity and has a unique substrate specificity from other CYP2D subfamilies. Western blot analysis suggested that the dog CYP2D15 contents were less than 4% of the total liver P450 content, assuming that 100% of expressed CYP2D15 incorporated heme.

Animals↗

PubMed1998

Regio- and stereoselectivity in propranolol metabolism by dog liver microsomes and the expressed dog CYP2D15.

We have studied the regio- and stereoselectivity of ring-hydroxylation and N-desisopropylation of S(-)- and R(+)-propranolol, using dog liver microsomes and the expressed dog CYP2D15 in insect cells. In dog liver microsomes, 4-hydroxylation was the preferred pathway in S(-)-propranolol oxidation, while N-desisopropylation was the preferred pathway in R(+)-propranolol oxidation. S(-)-Propranolol was preferred over R(+)-propranolol as substrate for 4- and 5-hydroxylations, while R(+)-propranolol was the preferred substrate for N-desisopropylation at higher substrate concentrations. The expressed CYP2D15 had high catalytic activities toward 4-, 5-hydroxylation, as well as N-desisopropylation of both enantiomers. At the substrate concentrations used, 4-hydroxylation was the preferred pathway for the metabolism of both enantiomers, and S(-)-propranolol was the preferred substrate over R(+)-propranolol for all three monooxygenations catalyzed by CYP2D15. Anti-CYP2D15 peptide antibody strongly inhibited 4- and 5-hydroxylation of both enantiomers in dog liver microsomes, while it did not inhibit their N-desisopropylation. These findings suggest that CYP2D15 is highly responsible for the stereoselective 4- and 5-hydroxylations of propranolol in dog liver microsomes.

Animals↗

PubMed1998

Molecular basis of the Dark Agouti rat drug oxidation polymorphism: importance of CYP2D1 and CYP2D2.

The Dark Agouti rat has been proposed as a model for the human debrisoquine 4-hydroxylase polymorphism. Earlier studies suggested that the poor metabolizer phenotype in the Dark Agouti rat is caused by the absence of the expression of CYP2D1 mRNA. Although CYP2D1 is the major enzyme catalyzing debrisoquine 4-hydroxylation, other reports have indicated the involvement of a CYP2D, purified from rat hepatic microsomes and presumed to be CYP2D2, which also exhibits this activity. The levels of CYP2D1 and CYP2D2 mRNAs were markedly lower in Dark Agouti as compared to Sprague Dawley rats. Using a baculovirus expression system, recombinant CYP2D1 and CYP2D2 from Spodoptera frugiperda insect cells were examined and were found to both forms catalize debrisoquine 4-hydroxylase activity. These results suggest that reduced debrisoquine 4-hydroxylase activity in the Dark Agouti rat is caused by the low level expression not only of CYP2D1, but also of CYP2D2. Interestingly, bunitrolol 4-hydroxylation was catalyzed by recombinant CYP2D2, while CYP2D1 was inactive toward this substrate. Thus, the low bunitrolol 4-hydroxylation in Dark Agouti rats was caused by the low level of CYP2D2 expression in this rat strain.

Adrenergic beta-Antagonists↗

PubMed1998

Assignment of Vibrio sp. strain ABE-1 to Colwellia maris sp. nov., a new psychrophilic bacterium.

A psychrophilic bacterium, previously described as Vibrio sp. strain ABE-1T, has been reassigned by phenotypic characterization, chemotaxonomic analysis and 16S rRNA phylogenetic analysis. The organism was curved rods and it could reduce nitrate to nitrite and hydrolyse gelatin and DNA, but not chitin. NaCl was required for growth. This strain was susceptible to the vibriostatic compound O/129. The major isoprenoid quinone was ubiquinone-8 and the DNA G + C content was 39.4 mol%. The whole-cell fatty acids comprised saturated and monounsaturated fatty acids with 10-18 C atoms; saturated and monounsaturated C16 fatty acids were predominant. Strain ABE-1T contained the unique trans-unsaturated fatty acid, 9-trans-hexadecenoic acid. Although strain ABE-1T has been identified as a Vibrio species, the strain did not ferment glucose. Phylogenetic analysis based on 16S rRNA sequencing indicated that strain ABE-1T was more closely related to Colwellia species than to Vibrio species. However, strain ABE-1T differed from other reported Colwellia species in terms of phylogenetic position, some phenotypic characteristics, chemotaxonomic analysis and relatedness by DNA-DNA hybridization. Accordingly, the name Colwellia maris is proposed. The type strain is ABE-1T (= JCM 10085T).

Base Composition↗

PubMed1998

Tumor-specific activation of mitogen-activated protein kinase in human colorectal and gastric carcinoma tissues.

To search for the signaling events in colorectal carcinoma relevant to its tumorigenesis, we investigated the activity of mitogen-activated protein kinase (MAPK) in human colorectal carcinoma tissues and paired normal tissues. Of 64 cases examined, approximately 75% (48 cases) showed tumor-specific activation of MAPK by in situ kinase renaturation assay, as well as in vitro kinase assay with immunoprecipitated MAPK. In addition, tumor-specific activation of MAPK was associated with the activation of MAPK kinase in the cases we examined. However, no clear correlation of MAPK activation with lymph node involvement, metastatic rate, stage, histological classification, age or sex was observed. These results suggest that the MAPK pathway is involved in colorectal tumor development, but its activation alone is not sufficient for malignant conversion. In contrast to colorectal carcinoma, gastric carcinoma tissues showed a lower rate of MAPK activation, suggesting that the signaling pathway activated in colorectal carcinoma tissues may differ in part from that of gastric carcinoma.

Adult↗

PubMed1998

Response of parathyroid hormone to anaerobic exercise in adolescent female athletes.

It has been shown that moderate exercise suppresses parathyroid hormone (PTH) secretion, while strenuous exercise is apt to induce continuous secretion, which has a negative effect on bone mineral densities (BMD). The present study investigated a typical response of PTH to brief exercise. The study group comprised six adolescent female basketball players whose BMD were within normal limits. Maximal anaerobic power by three-step cycling was loaded on each subject. The first blood sample was drawn 30 min prior to testing test, the second was immediately following, the third was 15 min after, and the fourth was 30 min after. The proportional change in plasma volume was -11.5% immediately following (P < 0.05), +2.1% 15 min after, and +5.5% at 30 min after exercise (P < 0.05). The expected value was calculated on the assumption of no effect, except changes in plasma volume, by exercise. The measured values of PTH and calcium (Ca) immediately after exercise were lower than each of the expected values (P < 0.05 for both). At 15 min after, there was no significant difference between expected and measured values of PTH, Ca and magnesium (Mg), respectively. At 30 min after, the measured value of Ca and Mg was higher than each expected value (P < 0.05 for both). It was concluded that PTH secretion is suppressed transiently immediately after maximal anaerobic exercise and is then stimulated during the recovery time in normal BMD subjects.

Adolescent↗

PubMed1998

Role of the transition zone for elevating serum prostate-specific antigen in benign prostatic hyperplasia.

BACKGROUND: Patients with benign prostatic hyperplasia (BPH) have a wide range of concentrations of PSA. However, it is not known what factors influence the concentration of serum PSA other than the prostate volume. BPH is composed of an enlarged transition zone (TZ) and other zones (nonTZ). The TZ is thought to play a more important role than the nonTZ in determining the concentration of serum PSA in BPH patients. METHODS: We investigated the individual glandular zone volume, the amount of PSA produced by each zone and the PSA density in each zone in 23 patients with histologically-confirmed BPH. The PSA density in the TZ was calculated by dividing the difference between the serum PSA before and after surgical resection by the specimen weight. We examined the influence of these parameters on the concentration of serum PSA in BPH patients. RESULTS: The serum PSA concentration correlated with the amount of PSA produced by the TZ (r=0.90, P< 0.0 1), but not the nonTZ (r=0.25, P=0.29). The concentration of serum PSA also showed a significant correlation with the TZ volume (r=0.67, P< 0.01) and the PSA density in the TZ (r=0.51, P< 0.05), but not with the PSA density in the nonTZ (r=-0.06, P=0.81). Also, age was inversely correlated with the PSA density in the TZ (r=-0.69, P< 0.01). CONCLUSION: The hypertrophic prostate cell volume (TZ volume) and activity (PSA density in the TZ) significantly correlated with the concentration of serum PSA in BPH patients, and the TZ cell activity decreased inversely with age in these BPH patients.

Age Factors↗

PubMed1998

Genetic and epigenetic alterations of the estrogen receptor gene and hormone independence in human breast cancer.

The existence of hormone-independent tumors is a substantial problem for the present endocrine treatment of breast cancers. Estrogen receptor (ER) gene mutation can change the biochemical activity of the protein and can affect hormone responsiveness. However, quite a few mutations of significance have been described in breast cancer. Recently, numerous variant ERs have been detected at the mRNA level with alternative splicing, yielding deletion of exon 3, 5, or 7. The truncated ER protein induced from variant mRNA could mainly be exhibited as a repressor through dominant negative effects on normal ER protein. The mechanism of the loss of hormone dependency is, however, still very complex. Further work to assess the correlation between clinical behavior and ER variants is required to determine whether these variants play a role in hormone-resistant disease. Additionally, the DNA methylation of the ER gene itself may control ER expression. These epigenetic changes can play an important role in the loss of hormone dependence in breast cancer.

Alternative Splicing↗

PubMed1998

[An evaluation of the biting force, the body composition and the amount of masticatory action in young females].

UNLABELLED: The purposes of this study were to investigate factors related to maximum biting force and to understand the characteristics of physical properties of daily ingested foods in young females. One hundred and forty subjects aged 18-23, with Angle 1 class occlusion, had not suffered from periodontitis, and had not been treated for preparation of tooth crown of first molars. Body height and weight were measured, and percentage of body fat, fat mass (FM) and lean body mass (LBM) were estimated, using the impedance analyzer. The maximum biting force was measured by the press sensation method. According to the formula on the basis of our new version of Yanagisawa's food classification, the mean value of the amount of masticatory action for one day was calculated. Subjects were divided into the normal biting force and the low biting force groups with -1SD of the maximum biting force, in order to compare body composition and backgrounds in sports activities between these two groups. Multiple linear regression analysis was carried out, employing maximum biting force (kg.f) as a dependent variable, and having a background in sports activities, FM, LBM, the number of missing teeth, the number of dental caries and the amount of masticatory action for one day as independent variables. Results were as in the following: 1) The proportion of subjects who had a background in sports activities in the low biting force group were less than that in the normal biting force group (p < 0.01). 2) Having a background in sports activities and LBM were positively correlated to maximum biting force (p < 0.01), while the amount of masticatory action for one day was not. 3) All subjects, especially those in the low biting force group seldom had food requiring the highest amount of masticatory action. CONCLUSION: Having a background in sports activities and LBM are positively correlated with the maximum biting force, while the amount of masticatory action for one day was not correlated positively nor negatively in young females.

Adolescent↗

PubMed1998

[The presentation level of interrupted pure tone for inducing the pulse phenomenon of continuous white noise].

When two sounds which have same spectrum but different amplitude are alternated without silent gap between the sounds, the lower amplitude sound comes to be heard as continuous. This is called "auditory induction" which is one of the most interesting auditory phenomena. The fainter sound is called induce and the louder sound is called inducer. The authors previously reported that the addition of interrupted pure tone to continuous white noise induced the pulsed noise. This pulse phenomenon was thought to be a kind of auditory induction; the inducer is the noise image of white noise with the silent part of interrupted pure tone and the induce is the noise image of white noise with the pure tone part of interrupted pure tone. The authors hypothesized that an auditory filter made with the pure tone of interrupted pure tone generates the two noise images in the continuous white noise. Present experiments were made to investigate the change of "the threshold of interrupted pure tone for inducing the pulse phenomenon" (TIP) when the presentation level of continuous white noise and the frequency of interrupted pure tone are changed. TIP was constant and independent of both the amplitude of continuous white noise and the frequency of interrupted pure tone. All subjects reported that the higher the frequency of interrupted pure tone is, the harder it becomes to hear the pulsed noise image. It is supposed that this phenomenon does not contradict the theory of the auditory filter.

Acoustic Stimulation↗

PubMed1998

Diagnosis and sero-epizootiology of equine herpesvirus type 1 and type 4 infections in Japan using a type-specific ELISA.

Recently, a type-specific ELISA using equine herpesvirus type 1 (EHV-1) and type 4 (EHV-4) glycoprotein Gs (gGs) was developed by Crabb and Studdert [1993]. To investigate the dissemination of EHV-1 and -4 among horses in Japan, we applied their ELISA as suitable for discriminating between EHV-1 and -4 infections serologically. Type-specificity of the ELISA was confirmed by using paired sera of infected horses with either EHV-1 or -4. Application of the ELISA to sera collected before and after the winter season of 1995-1996 from 80 racehorses revealed that 30 horses showed significant antibody responses against EHV-1 and 9 against EHV-4, respectively. The results indicated that this ELISA using paired sera is useful for a diagnosis and an epizootiological study on EHV-1 and -4 infections.

Animals↗

PubMed1998

Effect on the femur of a new hip fracture preventive system using dropped-weight impact testing.

To reduce hip fractures during falls, we devised a new hip fracture preventive system to attenuate impact on the greater trochanteric region and studied the effects of the system on the femur. Twelve coupled, embalmed, cadaveric femora were used. Right femora were fractured without protection as a control and compared with left femora covered by the protection system, which consisted of a silicone gel pad or the silicone gel pad combined with a resin cover. The impact of a fall was simulated by mounting a femur in the horizontal plane and dropping an 8.4 kg mass on its greater trochanteric region. The impact load and time were measured using a load cell within the mass. The maximum strain during impact at the inferior side of the femoral neck was determined from an attached strain gauge. Trochanteric fractures were produced in 18 of the 24 femora (75%). The mean impact load for a drop height of 25 cm was reduced from 3117 N to 2176 N by silicone gel (p < 0.01) and to 1681 N by the addition of the resin cover (p < 0.01). The mean maximum strain was similarly reduced from 2276 microvarepsilon to 1872 microvarepsilon (p = 0.15) and to a mean 1559 microvarepsilon (p < 0. 05). The mean impact time was prolonged from 13 ms to 20 ms (p < 0. 01) and 22 ms (p < 0.01), respectively. The effect of the cover became more conspicuous as height increased. We concluded that the silicone gel pad provided effective impact attenuation, and the addition of the rigid cover was even more effective for impact reduction. This system was thought to be clinically useful in preventing hip fractures.

Absorptiometry, Photon↗

PubMed1998

TNF-alpha increases expression of IL-6 and ICAM-1 genes through activation of NF-kappaB in osteoblast-like ROS17/2.8 cells.

Tumor necrosis factor-alpha (TNF-alpha) plays a key role in inflammatory diseases such as rheumatoid arthritis and in postmenopausal osteoporosis. In various tissues, TNF-alpha action is mediated by a transcription factor, nuclear factor-kappa B (NF-kappaB). However, little is known about how TNF-alpha exerts its action in osteoblasts. We thus examined the effect of TNF-alpha on the activation of NF-kappaB in rat osteoblast-like osteosarcoma cells (ROS17/2.8). Electrophoretic mobility shift assay revealed that the activation of the p50-p65 heterodimer NF-kappaB was induced by TNF-alpha as early as 15 minutes followed by a persistent activation for 48 h. When the binding activity of NF-kappaB in cytosol was examined using detergents that dissociate NF-kappaB from an inhibitory protein IkappaB, it decreased during the initial 30 minutes and then increased to the unstimulated level. Northern blot analysis revealed a marked increase in the mRNA levels of p105, a precursor of p50, 6 h after TNF-alpha and a gradual increase in p65 mRNA levels during the initial 1 h. Significant increase in both mRNA levels continued until 24 h after TNF-alpha. These results suggest that the rapid activation of NF-kappaB by TNF-alpha is mainly due to the nuclear translocation of NF-kappaB pre-existing in cytosol, and that the subsequent increase in the expression of p50 and p65 may result in the persistent activation of NF-kappaB during TNF-alpha stimulation. TNF-alpha also increased the mRNA levels of interleukin-6 (IL-6) and intercellular adhesion molecule-1 (ICAM-1). An antioxidant, N-acetyl-L-cysteine, significantly attenuated the TNF-alpha-dependent increase in these mRNAs, and simultaneously reduced the activation of NF-kappaB by TNF-alpha, indicating that NF-kappaB mediates the TNF-alpha-dependent expression of IL-6 and ICAM-1 in ROS17/2.8 cells. These results suggest that the activation of NF-kappaB by TNF-alpha may play an important role in the production of cytokines and cell adhesion molecules from osteoblasts, leading to the promotion of bone resorption and inflammation.

Acetylcysteine↗

PubMed1998

Surgical successful treatment of Cushing's syndrome in a pregnant patient complicated with severe cardiac involvement.

We encountered a case of a pregnant woman with adrenal causes of Cushing's syndrome who exhibited congestive heart failure as an initial symptom. Since the patient was also a diabetic, we treated her with high levels of diuretics and insulin. Echocardiography revealed a remarkable thickening of the left ventricle without asymmetric hypertrophy. The diagnosis of Cushing's syndrome caused by adrenal adenoma was confirmed by the endocrinological data and magnetic resonance imaging. The right adrenal adenoma was removed in the 28th week of pregnancy. After the operation, her congestive heart failure and hyperglycemia dramatically improved. Five weeks after the operation, she delivered a normal infant by caesarean section without complications. Only 4 months after delivery, the thickening of her left ventricle was normalized. We consider that the progression of her left ventricular hypertrophy induced by the changes in hemodynamic load during pregnancy may have been augmented by the excess of plasma cortisol. Operative therapy may be recommended for pregnant Cushing's syndrome patients with severe hypercortisolism complicating congestive heart failure.

Adenoma↗

PubMed1998

Health surveillance of forestry workers exposed to hand-arm vibration in Wakayama from 1974 to 1996.

To clarify the trends in the number and the severity of vibration syndrome in Wakayama for these 23 years, the records of the medical examinations for vibration syndrome were analyzed with 4,652 (a total of 9,920) private forestry workers exposed to hand-arm vibration. The number of the subjects who took the medical examinations reached a maximum of 1,242 in 1978. After that, it decreased year by year, but remained at about 300 or less from 1988. There was a corresponding increase in age and the number of years of operating chain saws among the subjects examined. The compensated cases reached a maximum number of 393 cases in 1977, and then a drastic decrease was noted. Year by year there was an increase in the number of cases whose medical examinations revealed no abnormality. The regional occupational health care system including the surveillance card, which has been active since 1975, has probably contributed to the decrease or prevention of occurrence of vibration syndrome in Wakayama.

Adult↗

PubMed1998

Finger skin temperature and laser-Doppler finger blood flow in subjects exposed to hand-arm vibration.

OBJECTIVES: This study was aimed to assess the peripheral circulatory functions of forestry workers exposed to hand-arm vibration, using simultaneous measurements of finger skin temperature (FST) and finger blood flow (FBF). METHODS: The subjects were five men with vibration-induced white finger (VWF), four subjects with numbness in their hands and five exposed controls without any signs or symptoms related to vibration syndrome. Simultaneous measurements of FST and laser-Doppler FBF were performed before, during and following a 10-min recovery period after the hand was immersed in cold water (10 degrees C, 10 min). Partitional measurements of finger blood flows could be made between the capillaries and deeply located vessels using two laser-Doppler flow probes having narrower and wider optic fiber separations. RESULTS: The FST as well as the FBF of the capillary and deeply located vessels during and following the cold immersion test in those with VWF and in the subjects with numbness had a slight increase immediately following the cold immersion and no tendency to be augmented as the time span increased. After the cold immersion test, the control group had significantly greater FST and FBF compared to other groups. Particularly, from the 5th to the 10th min after the cold provocation, the values of FBF of the deeply located vessels in those with VWF were significantly lower than the controls. During the course of observation, the FST had significantly linear relationship with the recorded capillary and deep FBF values, and that was much closely correlated with the deep FBF (i.e., P < 0.01 in each selected condition). The slope of the regression lines in the capillary were steeper and shallow in the deep FBF. CONCLUSIONS: In addition to the measurement of capillary FBF, more detailed and accurate information on the peripheral circulatory functions of vibration-exposed subjects can be obtained by including the assessment of the deep FBF.

Aged↗

PubMed1998

Suppression of cell growth by ectopic expression of N-cadherin.

We found that ectopic expression of N-cadherin in 3Y1 caused tight association of cells and, thereby, substantially suppressed cell growth. N-cadherin expression inhibited neither tyrosine phosphorylation of cellular proteins, GTP uptake onto Ras, nor activation of MAP kinase, suggesting that it does not directly interfere the Ras-MAP kinase pathway. However, co-expression of N-cadherin with dominant negative Ras, S17N Ras, showed synergestic growth inhibitory effect, suggesting that N-cadherin signaling antagonizes the Ras-MAP kinase signaling. In addition, we found that N-cadherin yielded cell-cycle arrest at G0/G1 phase. These results strongly suggest that N-cadherin cell adhesion machinery works as a negative controller of cell cycle in 3Y1 and this growth suppressive function of cadherin is distinct from the epithelial morphogenetic function.

Actins↗

PubMed1998

[Obesity as one of the risk factors for urolithiasis].

BACKGROUND: It is well known that many diseases may be associated with obesity resulting from an energy-rich diet, and that a westernized diet may increase the incidence of urinary stone formation. To evaluate degree of obesity, we investigated body mass index (BMI) in patients with calcium containing upper urinary stones and examined their blood with regard to lipid metabolism. METHODS: Between July 1994 and December 1995, we analyzed 332 fresh renal-stone formers (253 males and 79 females) who visited 7 hospitals located in Ehime prefecture. As a control, 949 residents older than 20 years (387 males and 562 females) of the same prefecture were also examined by the annual Ehime prefecture office report of 1994. Body mass index as degree of obesity, stone-recurrence, blood test and other complicated diseases were examined. RESULTS: In male stone formers the rate of obesity was significantly higher than that of control males (p < 0.001). The differences were seen only in their twenties and fifties. Furthermore, among male stone formers the rate of obesity was significantly higher in recurrent stone formers than in single stone formers (p < 0.05). On the other hand, in female, there was no significant difference in the rate of obesity between stone formers and controls. No difference was seen between recurrent stone formers and single stone formers. In the blood test, there was no differences in the level of calcium, phosphate and uric acid between stone formers and controls. The level of cholesterol and triglyceride in male were significantly higher in controls (p < 0.01) and there was no difference in the level of high density lipoprotein (HDL) between stone formers and controls. Among the stone formers, 48 males (20.0%) and 17 females (21.5%) had other diseases. The rate of complicated diseases was similar to that of controls and no specific diseases in the stone formers were identified. CONCLUSION: Our report suggested that obesity in male should be considered as a risk factor for calcium containing stone formation.

Adult↗