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Biomedical subjects

T Furukawa

Publications and source records attributed to T Furukawa.

At least 271 records · Page 15Linked to original sources
PubMed1997

Intra-individual versus extra-individual components of social support.

BACKGROUND: Most studies of social support appear to assume that it is something that the external environment provides to an individual. However, longitudinal and genetic studies are beginning to question this assumption. The purpose of the present study is to differentiate quantitatively the intra-individual determinants of social support from its extra-individual components. METHODS: The subjects were 103 high school exchange students who were enrolled in a 1-year placement with a host family in various countries of the world. The People In Your Life scale, a reliable and validated self-report measure of perceived social support, was administered before their departure from home, after 6 months of stay in a completely unfamiliar foreign community and 6 months after their return home. Structural equation models were examined that partitioned the intra-individual and extra-individual components of social support, and the best fitting models were selected. RESULTS: Between 24% and 69%, or up to 86% depending on the situation, of the variances of social support measures were stable across situations and considered intra-individual; 31% to 76% of what is measured as social support was of extra-individual origin. Moderately strong correlations were noted between the intra-individual components and the trait extraversion. CONCLUSIONS: Measures of social support, which is usually tacitly understood as something extrinsic to an individual, in fact may not be measures of the external environment only.

Adaptation, Psychological↗
PubMed1997

Voltage and pH dependent block of cloned N-type Ca2+ channels by amlodipine.

1. Two types of Ca2+ channel alpha1-subunits were co-expressed in Xenopus oocytes with the Ca2+ channel alpha2- and beta1-subunits. The Ba2+ current through the alpha1C alpha2beta and the alpha1B alpha2beta channels had electrophysiological and pharmacological properties of L- and N-type Ca2+ channels, respectively. 2. Amlodipine had a strong blocking action on both the L-type and N-type Ca2+ channels expressed in the oocyte. The potency of the amlodipine block on the N-type Ca2+ channel was comparable to that on the L-type Ca2+ channel. At -100 mV holding potential, the IC50 values for amlodipine block on the L-type and N-type Ca2+ channel were 2.4 and 5.8 microM, respectively. 3. The blocking action of amlodipine on the N-type Ca2+ channel was dependent on holding potential and extracellular pH, as has been observed with amlodipine block on the L-type Ca2+ channel. A depolarized holding potential and high pH enhanced the blocking action of amlodipine. 4. The time course of block development by amlodipine was similar for L-type and N-type Ca2+ channels. However, it was slower than the time course of block development by nifedipine for the L-type Ca2+ channel.

Amlodipine↗
PubMed1997

ATP release and contraction mediated by different P2-receptor subtypes in guinea-pig ileal smooth muscle.

1. The present study was addressed to clarify the subtypes of P2-purinoceptor involved in ATP release and contraction evoked by alpha, beta-methylene ATP (alpha, beta-mATP) and other P2-agonists in guinea-pig ileum. 2. alpha, beta-mATP 100 microM produced a transient and steep contraction followed by ATP release from tissue segments. These maximum responses appeared with different time-courses and their ED50 values were 5 and 25 microM, respectively. The maximum release of ATP by alpha, beta-mATP was markedly reduced by 250 microM suramin, 30 microM pyridoxal-phosphate-6-azophenyl-2',5'-disulphonic acid (PPADS) and 30 microM reactive blue 2 (RB-2), P2-receptor antagonists. However, the contractile response was inhibited by suramin, tetrodotoxin and atropine, but not by PPADS and RB-2. 3. Although the contraction caused by alpha, beta-mATP was strongly diminished by Ca(2+)-removal and nifedipine, and also by tetrodotoxin and atropine at 0.3 microM, the release of ATP was virtually unaffected by these procedures. 4. UTP, beta, gamma-methylene ATP (beta, gamma-mATP) and ADP at 100 microM elicited a moderate release of ATP. The release caused by UTP was virtually unaffected by RB-2. However, these P2-agonists failed to elicit a contraction of the segment. 5. The potency order of all the agonists tested for the release of ATP was alpha, beta-mATP > UTP > beta, gamma-mATP > ADP. 6. In superfusion experiments with cultured smooth muscle cells from the ileum, alpha, beta-mATP (100 microM) enhanced the release of ATP 5 fold above the basal value. This evoked release was inhibited by RB-2. 7. These findings suggest that ATP release and contraction induced by P2-agonists such as alpha, beta-mATP in the guinea-pig ileum result mainly from stimulation of different P2-purinoceptors. P2Y-like purinoceptors on the smooth muscles and, probably, P2X-purinoceptors on cholinergic nerve terminals, respectively. However, the ATP release may also be mediated, in part, by P2U-receptors, because UTP caused RB-2-insensitive ATP release.

Adenosine Triphosphate↗
PubMed1997

Primary familial polycythaemia associated with a novel point mutation in the erythropoietin receptor.

Primary familial and congenital polycythaemia (PFCP) is a rare disease characterized by congenital erythrocytosis inherited in an autosomal dominant fashion. Recently, mutations in the erythropoietin receptor (EpoR) have been identified in PFCP families. We describe a Japanese family with an autosomal dominant inheritance of PFCP. An in vitro colony assay demonstrated hypersensitivity of erythroid progenitors to erythropoietin (Epo) in affected family members. Sequence analysis of RT-PCR products amplified from the C-terminal region of EpoR transcripts in affected family members revealed that they were all heterozygous for C and T bases at position 5986, which suggested a genetic mutation (C to T) on one allele of EpoR. This mutation gave rise to a translation termination codon TAG at amino acid 435. Thus, the resulting EpoR is a truncated protein product lacking all 74 amino acids downstream of the mutation. To date, all genetic mutations affecting a family with PFCP, including this one, have been located in the cytoplasmic negative regulatory region of the EpoR. All mutations gave rise to truncated Epo receptors between Tyrosine 427 and Tyrosine 455. The phosphotyrosines in this region of EpoR have been demonstrated to be binding sites for SHP-1 phosphatase. Therefore PFCP is presumably brought about as a result of genetic mutations which cause the loss of the SHP-1 binding site in the cytoplasmic region of EpoR.

Base Sequence↗
PubMed1997

Intraductal ultrasonography of the pancreas: development and clinical potential.

Intraductal ultrasound (IDUS) probes mounted with 30 MHz or 20 MHz transducers were evaluated in the diagnosis of 239 patients with pancreatic disease (including 48 cancers, 90 mucin-producing tumors, seven islet-cell tumors, two metastatic pancreatic tumors, seven serous cystadenomas, one pancreatic teratoma, three solid cystic tumors, 49 cases of chronic pancreatitis, 25 cases of focal pancreatitis, and seven cases of pancreatolithiasis). The probe was inserted via the papilla into the main pancreatic duct. In terms of resolution, IDUS at 20 MHz was able to image cystic lesions of less than 30 mm in diameter and solid lesions of less than 20 mm in diameter. With regard to vessels, IDUS was able to image the entire cross-section of the portal vein and other large veins. IDUS was useful in detecting carcinoma in situ and small tumors, in assessing the intraductal spread of the tumor and its pancreatic parenchymal invasion in mucin-producing tumors of the main duct, and in assessing the indications for surgery by revealing mural nodules in mucin-producing tumors of the ductal branches. IDUS was also useful in evaluating the feasibility of partial resection of the tumor in mucin-producing tumors of the ductal branches and pancreatic islet-cell tumors, in accurately locating multiple lesions in pancreatic islet-cell cancer, and in differentiating benign from malignant cases of localized stenosis of the main pancreatic duct related to pancreatic stenting. With IDUS, the site of pancreatic stones could be identified in order to assess the need for endoscopic treatments such as stenting of the pancreatic duct and the bile duct, and the use of pulsed-dye laser treatment under pancreatoscopy for pancreatic stones. Acute pancreatitis as a complication occurred in one of the 239 patients who underwent IDUS (0.4%). An awareness of the limitations and usefulness of IDUS in evaluating pancreatic diseases can contribute to the treatment of these conditions.

Aged↗
PubMed1997

Urine viscosity after injections of iotrolan or iomeprol.

PURPOSE: Previous observations in rats caused us to speculate whether the injection of iotrolan, a nonionic dimeric contrast medium (CM), would increase urine viscosity enough to obstruct urine outflow in the collecting duct. MATERIAL AND METHODS: The urine viscosity in dogs was measured directly with a viscosimeter after injections of iotrolan or of iomeprol, a nonionic monomeric CM. RESULTS AND CONCLUSION: The injection of iotrolan increased urine viscosity considerably whereas iomeprol had little effect on this variable. The osmolality-dependent adverse reactions of CM have previously been emphasized but viscosity-dependent adverse reactions must also be considered when the CM is a polymer with a low osmolality.

Animals↗
PubMed1997

Permeability of contrast media through hemodialysis membrane.

PURPOSE: To compare the permeability of 10 contrast media (CM) through the hemodialysis membrane. MATERIAL AND METHODS: An experimental model was constructed from clinical hemodialysis equipment. The 10 CM that were used were: diatrizoate, iothalamate, iopamidol, iohexol, iopromide, ioversol, iomeprol, ioxaglate, iodixanol and iotrolan. They were dissolved into the dialysate. Each solution ran into the blood circuit of the dialyzer at a rate of 200 ml/min and into the dialysate circuit of the dialysis machine at a rate of 500 ml/min. Permeability was expressed as clearance, calculated from the iodine concentration at the afferent and efferent lines of the dialyzer, and from the blood-flow rate. RESULTS: The clearance of all the monomeric CM was superior to that of all the dimeric CM. Values of clearance and molecular weight correlated well. CONCLUSION: The molecular weight of a contrast medium is the main factor that influences the efficiency of CM removal by hemodialysis.

Cellulose↗
PubMed1997

Regulation of the ferrochelatase gene expression during differentiation of mouse erythroleukemia cells.

Ferrochelatase [EC 4.99.1.1], the last step enzyme of heme biosynthesis, is transcribed from a single promoter. The enzyme is ubiquitously expressed in all cells, while the transcription is induced during erythroid differentiation. In a transient transfection assay, we identified two cis-acting elements involved in regulating the human ferrochelatase gene in mouse erythroleukemia (MEL) cells; one is the distal region (-108 to -95) for the basic expression in erythroid and non-erythroid cells, and the other is the proximal region (-80 to -72) corresponding to the induced expression during differentiation of dimethylsulfoxide-treated MEL cells. DNase I footprinting and gel mobility shift analyses revealed the presence of nuclear protein binding to the distal and the proximal regions, in both induced and uninduced MEL cells. These mean that two promoter regions play an important role in regulating the induced expression of ferrochelatase.

Animals↗
PubMed1997

An assessment of dobutamine echocardiography and end-diastolic wall thickness for predicting post-revascularization functional recovery in patients with chronic coronary artery disease.

AIMS: This study investigated the functional outcome of wall-thinned, akinetic myocardium after revascularization and evaluated the accuracy of dobutamine echocardiography in predicting post-revascularization functional recovery with the assessment of end-diastolic wall thickness in chronic ischaemic patients. METHODS AND RESULTS: Fifty-three patients underwent dobutamine echocardiography before coronary revascularization. End-diastolic wall thickness was also evaluated before and after revascularization. The sensitivity and specificity of dobutamine echocardiography to predict postrevascularization functional recovery were 69% and 100% in 58 akinetic/dyskinetic segments, and 86% and 57% in 96 hypokinetic segments. Of 19 akinetic/dyskinetic segments with a preserved end-diastolic wall thickness, 17 (89%) showed functional recovery after revascularization, and dobutamine detected 14 (83%) of these 17 segments. Of 39 akinetic/dyskinetic segments with a thinned end-diastolic wall thickness, 15 (38%) achieved functional recovery, whereas dobutamine echocardiography detected recovery in only eight (53%). Further, of these 15 viable, Wall-thinned segments, 12 (80%) showed an increased end-diastolic wall thickness after revascularization (mean +/- SD were from 5.6 +/- 0.7 mm at baseline to 7.4 +/- 1.3 mm and 9.7 +/- 1.4 mm after 1 week and after 3 months, respectively), and only 5 (42%) of these responded to dobutamine. CONCLUSION: Dobutamine echocardiography showed a lessened sensitivity to predict post-revascularization functional recovery in akinetic/dyskinetic segments with a thinned end-diastolic wall thickness that subsequently increased in size.

Adult↗
PubMed1997

Sojourner readjustment: mental health of international students after one year's foreign sojourn and its psychosocial correlates.

The problem of readjustment to the home culture among international students who have spent some time in a foreign culture has not received satisfactory empirical investigation in the literature. We present a longitudinal study of the readjustment of 199 Japanese adolescents who have been enrolled in 1-year placement with a host family in various countries of the world. The personality trait, coping style, social support, and emotional distress of the subjects were measured before departure, while abroad, and 6 months after return home. The students showed substantial emotional distress even 6 months after return from a foreign sojourn; neuroticism, emotion-oriented coping, and concurrently measured social support were found to significantly predict mental health during readjustment. Close attention is recommended not only for the adjustment of the international students while abroad but also for the readjustment process involved in the so-called reverse culture shock.

Adaptation, Psychological↗
PubMed1997

Potentiation of dipsogenic actions by centrally administered type-C natriuretic peptide in spontaneously hypertensive but not Wistar-Kyoto rats.

1. The effects of type-C natriuretic polypeptides (CNP) on the central dipsogenic and pressor responses to angiotensin II (AngII) were studied by the administration of agents into the lateral cerebral ventricle under conscious and unrestrained conditions in normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR). 2. The fluid intake induced by AngII (25 ng) and water deprivation were potentiated after pretreatment with CNP in SHR but not in WKY rats. However, carbachol-induced water intake was not altered by pretreatment with CNP (2.5 micrograms) in either WKY rats or SHR. 3. In contrast, CNP did not influence the pressor responses to AngII in either WKY rats or SHR.

Angiotensin II↗
PubMed1997

Cultural distance and its relationship to psychological adjustment of international exchange students.

This study aimed to evaluate the reliability and validity of the Japanese version of the Cultural Distance Questionnaire (CDQ), and to examine whether or not the measured cultural distance influenced the psychological adjustment of international exchange students and, if so, which aspects were most influential. Subjects were 211 Japanese high school and college students who stayed for one year with a host family in one of 23 countries around the world. They were asked to complete the Maudsley Personality Inventory before departure from Japan, the 12-item General Health Questionnaire six months after arrival in the host country and the CDQ six months after they returned from abroad. We found that the CDQ had high internal consistency reliability. Satisfactory validity was suggested for the CDQ because it offered wide coverage of various aspects of daily lives that reflect cultural differences, because it was uncontaminated by social desirability or by personality traits and because the obtained scores by country and region were largely in accordance with the expected directions. It was found that the greater the cultural distance between Japan and the foreign community, as measured by the CDQ, the greater the psychological distress of the international student placed in that community. Furthermore, the results showed that it was the food that had the greatest impact on the intercultural adjustment.

Acculturation↗
PubMed1997

Typus melancholicus is not the premorbid personality trait of unipolar (endogenous) depression.

The present paper aims to examine whether Typus melancholicus is a distinguishing premorbid personality of unipolar (endogenous) depressive patients vis-à-vis psychiatric patients with different diagnoses and healthy control subjects. Two observer-rated scales for Typus melancholicus were administered to a consecutive series of psychiatric patients (n = 140) and a group of control subjects (n = 84). To the authors' own surprise, the only statistically significant finding was the low Typus melancholicus score among unipolar (endogenous) depressives in comparison with normal controls but not with other psychiatric patients. In addition, this finding held only for one of the two rating scales and among women only. According to the other rating scale for Typus melancholicus, there was no difference between unipolar (endogenous) depressives and the normal control or other psychiatric patients. These findings are discussed with particular emphasis on the methodological aspects of studies of premorbid personality of psychiatric disorders, a favored subject in the psychiatric science for decades.

Adolescent↗
PubMed1997

Screening for depression among first-visit psychiatric patients: comparison of different scoring methods for the Center for Epidemiologic Studies Depression Scale using receiver operating characteristic analyses.

The present paper aims to compare the ability of eight scoring methods for the Center for Epidemiologic Studies Depression Scale (CES-D), one of the most widely used self-report inventories for depression, to screen for a major depressive episode. The subjects were 591 patients who constituted representative samples of the first-visit patients to 23 psychiatric hospitals and clinics all over Japan. The criterion diagnoses were given by a semi-structured interview with established inter-rater reliability. The eight alternative scoring methods included the conventional Likert method, which gives the weights 0, 1, 2 and 3 to the four anchor points of the CES-D; the presence method, which gives the weights 0, 1, 1 and 1, respectively; the GHQ method, which gives the weights 0, 0, 1 and 1, respectively; the persistence method, which gives the weights 0, 0, 0 and 1, respectively; 10-item version, 5-item version, single-item version and the algorithmic method. On the basis of the receiver operating characteristic (ROC) analyses, it was found that the traditional Likert scoring method of the full CES-D performed best in detecting major depressive episodes among first-visit psychiatric patients. The presence method, the GHQ method and the 10-item version appeared to have a similar ability. The persistence method, the 5-item version and the single-item version resulted in significantly worse performance.

Adult↗
PubMed1997

Depressive symptoms among international exchange students, and their predictors.

The study described in the present paper prospectively examined the depressive symptoms displayed by a cohort of Japanese high school students (n=144) before and during their 1-year placements with volunteer host families in various countries under the aegis of an international cultural exchange programme. The subjects' level of depression showed a statistically significant increase 6 months after such a placement, but had returned to pre-departure levels by the completion of their 1-year placement. The variables that significantly predicted depressive symptoms during the placement in multiple regression analyses were the neuroticism score and the depressive symptoms measured prior to departure. However, the parental rearing practices and the fluency in the English language did not show a significant correlation. When measures of social support during the placement were entered, the perceived adequacy of social support was found to make an additional contribution to the prediction of depressive symptoms.

Acculturation↗
PubMed1997

[Incidence of Kanagawa phenomenon-positive and -negative Vibrio parahaemolyticus strains isolated from traveller's diarrhea and their relation to tdh and trh genes].

A total of 1,319 strains of Vibrio parahaemolyticus isolated from traveller's diarrhea were analysed for Kanagawa phenomenon (KP) with the Wagatsuma blood agar test and the results were also compared with those of analyses of tdh and trh genes which encode thermostable direct hemolysin (tdh) and TDH-related hemolysin (trh). The majority of the strains (1,152 strains) counting 87.3% had positive KP, among which 1,049 and 103 strains were only tdh and both tdh and trh-positive ones, respectively. However, 167 strains counting 12.7%, which is quite high compared to the previous report, were found to have negative KP, among which 94 and 24 strains were only trh and both tdh and trh-positive ones, respectively.

Bacterial Toxins↗
PubMed1997

Effects of baicalein on prostanoid generation from the lung and contractile responses of the trachea in guinea pig.

Effects of baicalein on release of slow reacting substance of anaphylaxis (SRS-A) or leukotriene (LT) from the sensitized guinea pig lung after antigen challenge and tonus of guinea pig tracheal muscles were studied. Baicalein inhibited release of SRS-A from sensitized guinea pig lung after antigen challenge. High-performance liquid chromatography (HPLC) analysis revealed that released SRS-A consisted to LTC4 and D4. Baicalein also reduced release of LTC4 and D4 from the sensitized lung after antigen challenge. Baicalein relaxed the isolated guinea pig tracheal smooth muscle contracted by LTD4, carbachol or histamine. However, this compound produced a contraction when the tracheal muscle was contracted by prostaglandin F2 alpha(PGF2 alpha). This contraction by baicalein was abolished by pretreatment with indomethacin, a cyclooxygenase inhibitor. Baicalein elicited a relaxation in the normal non-sensitized preparation but a contraction in the tissue isolated from actively sensitized guinea pig in 4 among 7 cases. Baicalein also produced a contraction in the trachea pretreated with phorbol dibutyrate and contracted by carbachol, which was eliminated after treatment with indomethacin. The results suggest that baicalein exerts action via, at least, two different mechanisms, the inhibition of releasing SRS-A (LTs) and direct relaxing effects on the trachea. Besides, baicalein seems to produce contraction under certain conditions, which may involve stimulation of the cyclooxygenase pathway.

Animals↗