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Biomedical subjects

K Yoshino

Publications and source records attributed to K Yoshino.

At least 19 recordsLinked to original sources
PubMed2001

Separate measurements of the flexoelectric and surface polarization in a model nematic liquid crystal p-methoxybenzylidene-p'-butylaniline: validity of the quadrupolar approach.

The temperature dependences of the surface polarization have been measured at the interface of a conductive glass with both the homogeneously and homeotropically oriented nematic liquid crystal p-methoxybenzylidene-p(')-butylaniline. The polarization was found in the field-off regime from the pyroelectric response of a cell to a short laser pulse, absorbed in the bulk of the liquid crystal. The temperature increment was calculated from the measurements of the birefringence induced by the same light pulse. It has been shown that the surface polarization at the homeotropic (m(h)) and planar (m(p)) interfaces is directed from an interface into the bulk and from the bulk to an interface, respectively (with a magnitude m(h) approximately -0.3 pC/m and m(p) approximately +0.2 pC/m at 25 degrees C). The experimental data may be explained in terms of the quadrupole model of the order-electric polarization with account of some additional contribution from molecular dipoles. The same technique also allows for the measurements of the z component of the flexoelectric polarization using a pyroelectric response of a hybrid (homeoplanar) aligned nematic cell and proper subtracting of the surface contributions. The flexoelectric polarization has been shown to be opposite to the sum of the surface terms m(h)+m(p) and directed from the planar to homeotropic interface. This means that the sum of the flexoelectric coefficients e=(e(1)+e(3)) is positive (e congruent with 1.7 pC/m at 28 degrees C). The temperature dependence of e has been shown to involve a combination of both the quadrupolar and dipolar contributions.

Journal Article↗
PubMed2001

Impaired FHIT expression characterizes serous ovarian carcinoma.

The FHIT (fragile histidine triad) gene on chromosome 3p14.2 is a candidate tumour suppressor gene. To define the role of the FHIT gene in the development of ovarian cancer, we have examined 33 ovarian carcinomas, 2 borderline tumours and 10 benign adenomas for the presence of FHIT gene alterations. FHIT transcripts were analysed by RT-PCR and sequencing. Aberrant FHIT transcripts were observed in 5/33 carcinomas (15%) and in 1 of 2 borderline tumours. Loss of normal FHIT transcript was observed in 5/33 carcinomas (15%) but not in 2 borderline tumours or 10 benign adenomas. Allelic losses at D3S1300 and D3S4103, both located within intron 5 of FHIT, were detected in 5/24 (21%) and 5/25 (20%) informative ovarian carcinomas, respectively. Expression of Fhit protein was analysed by immunohistochemistry in 44 carcinomas, 19 borderline tumours and 16 benign adenomas. Loss or significantly reduced expression of Fhit protein was observed in 6/44 (14%) ovarian carcinomas but not in any of 19 borderline tumours or 16 benign adenomas. The impaired Fhit protein expression was significantly correlated with the loss of normal FHIT transcription. Most notably, loss of normal FHIT transcript and impaired expression of Fhit protein occurred only in serous adenocarcinomas of grade 2 and 3 (5/15; 33% and 6/19; 32%, respectively). The present data suggest that inactivation of the FHIT gene by loss of expression is one of the important molecular events associated with the genesis of ovarian carcinoma, especially of high-grade serous carcinoma.

Acid Anhydride Hydrolases↗
PubMed2001

Similar subunit interactions contribute to assembly of clathrin adaptor complexes and COPI complex: analysis using yeast three-hybrid system.

Clathrin adaptor protein (AP) complexes are heterotetramers composed of two large, one medium, and one small subunits. By exploiting the yeast three-hybrid system, we have found that an interaction between the two large subunits of the AP-1 complex, gamma-adaptin and beta1-adaptin, is markedly enhanced in the presence of the small subunit, sigma1. Similarly, two large subunits of the AP-4 complex, epsilon-adaptin and beta4-adaptin, are found to interact with each other only in the presence of the small subunit, sigma4. Furthermore, we have found that an interaction between two large subunits of the COPI F subcomplex, gamma-COP and beta-COP, is detectable only in the presence of zeta-COP. Because these COPI subunits have common ancestral origins to the corresponding AP subunits, these three-hybrid data, taken together with the previous two-hybrid data, suggest that the AP complexes and the COPI F subcomplex assemble by virtue of similar subunit interactions.

Adaptor Protein Complex 1↗
PubMed2001

Cutting edge: IL-18-transgenic mice: in vivo evidence of a broad role for IL-18 in modulating immune function.

IL-18 has been shown to be a strong cofactor for Th1 T cell development. However, we previously demonstrated that when IL-18 was combined with IL-2, there was a synergistic induction of a Th2 cytokine, IL-13, in both T and NK cells. More recently, we and other groups have reported that IL-18 can potentially induce IgE, IgG1, and Th2 cytokine production in murine experimental models. Here, we report on the generation of IL-18-transgenic (Tg) mice in which mature mouse IL-18 cDNA was expressed. CD8+CD44high T cells and macrophages were increased, but B cells were decreased in these mice while serum IgE, IgG1, IL-4, and IFN-gamma levels were significantly increased. Splenic T cells in IL-18 Tg mice produced higher levels of IFN-gamma, IL-4, IL-5, and IL-13 than control wild-type mice. Thus, aberrant expression of IL-18 in vivo results in the increased production of both Th1 and Th2 cytokines.

Adjuvants, Immunologic↗
PubMed2001

Neostriatal stimulation activates tongue-protruder muscle, but not tongue-retractor or facial muscles: an electrical and chemical microstimulation study in rats.

Whether electrical microstimulation of a rat's striatal jaw region (SJR) in fact induced tongue or facial muscle activity in addition to jaw muscle activity was tested. Microstimulation of SJR-evoked EMG activity in a jaw-opener (anterior digastricus) and tongue-protruder (genioglossus). No activity was evoked in jaw-closers (temporalis or masseter), tongue-retractor (hyoglossus) or in facial muscles. In addition, the EMG effect could still be induced after extensive ablation of the neocortex; it was reproduced by microinjection of 50 mM kainic acid into SJR. The effective sites were histologically localized to a small central striatal region adjoining the anterior commissure. These findings may be of considerable value in understanding the striatal mechanism of orolingual dyskinesia involving involuntary jaw and tongue movements.

Animals↗
PubMed2001

Levitation of cylindrical particles in the sheath of an rf plasma.

Microrods were levitated in the collisional sheath of a rf plasma. Rods below a critical length settle vertically, parallel to the electric field, while longer rods float horizontally. Usually rods with other inclinations spin about a vertical axis. These experimental features fit well with a model that includes a theoretical profile for the sheath, a plasma model for the screening length, which increases going deeper in the sheath, and a plasma theory for the charging of the rod's elements. Despite the agreement this paper highlights the need for a better understanding of the charging mechanism of bodies in sheaths and of the transition region in collisional sheaths.

Journal Article↗
PubMed2001

Secreted Frizzled-related proteins can regulate metanephric development.

Wnt-4 signaling plays a critical role in kidney development and is associated with the epithelial conversion of the metanephric mesenchyme. Furthermore, secreted Frizzled-related proteins (sFRPs) that can bind Wnts are normally expressed in the developing metanephros, and function in other systems as modulators of Wnt signaling. sfrp-1 is distributed throughout the medullary and cortical stroma in the metanephros, but is absent from condensed mesenchyme and primitive tubular epithelia of the developing nephron where wnt-4 is highly expressed. In contrast, sfrp-2 is expressed in primitive tubules. To determine their role in kidney development, recombinant sFRP-1, sFRP-2 or combinations of both were applied to cultures of 13-dpc rat metanephroi. Both tubule formation and bud branching were markedly inhibited by sFRP-1, but concurrent sFRP-2 treatment restored some tubular differentiation and bud branching. sFRP-2 itself showed no effect on cultures of metanephroi. In cultures of isolated, induced rat metanephric mesenchymes, sFRP-1 blocked events associated with epithelial conversion (tubulogenesis and expression of lim-1, sfrp-2 and E-cadherin); however, it had no demonstrable effect on early events (compaction of mesenchyme and expression of wt1). As shown herein, sFRP-1 binds Wnt-4 with considerable avidity and inhibits the DNA-binding activity of TCF, an effector of Wnt signaling, while sFRP-2 had no effect on TCF activation. These observations suggest that sFRP-1 and sFRP-2 compete locally to regulate Wnt signaling during renal organogenesis. The antagonistic effect of sFRP-1 may be important either in preventing inappropriate development within differentiated areas of the medulla or in maintaining a population of cortical blastemal cells to facilitate further renal expansion. On the other hand, sFRP-2 might promote tubule formation by permitting Wnt-4 signaling in the presence of sFRP-1.

Animals↗
PubMed2001

Pulsed Doppler sonography of the hilar renal artery: differentiation of obstructive from nonobstructive hydronephrosis in children.

BACKGROUND/PURPOSE: It is difficult to detect the arcuate or cortical renal arteries when performing pulsed Doppler sonography (PDS) for congenital hydronephrosis. This study was undergone to assess the usefulness of PDS of the hilar renal artery to differentiate obstructive from nonobstructive hydronephrosis. METHODS: The authors performed PDS of the hilar renal artery in 80 normal children: 20 aged 0 to 1 months (group I), 20 aged 1 to 12 months (group II), 20 aged 1 to 6 years (group III), and 20 aged 7 to 15 years (group IV). Based on diuretic renography findings, 22 kidneys from 19 children with a ureteropelvic junction (UPJ) stricture were divided into 7 dilated obstructed and 15 dilated nonobstructed kidneys. The peak-systolic velocity (PSV), end-diastolic velocity (EDV), mean average velocity (Vm) and the resistive index (RI = [PSV - EDV]/PSV) were measured at the hilar renal artery. RESULTS: There was a significant difference in the RI of the hilar renal artery between obstructive and nonobstructive hydronephrosis. CONCLUSION: A pulsed Doppler evaluation of the hilar renal artery is useful for detecting an obstructive UPJ stricture compared with assessing arcuate or cortical renal arteries.

Adolescent↗
PubMed2001

Control of arterial partial pressure of oxygen in patients with respiratory abnormalities using an adaptive observer.

A system for controlling the arterial partial pressure of oxygen in patients on long-term oxygen therapy is proposed. After performing a parameter estimation of the model of pulmonary system, an adaptive observer is applied to perform the control task. The observer considers the model uncertainties as disturbances and rejects their impact on the system. As a result of this, the quality of the control can be drastically improved. The presented simulation and experimental results show the effectiveness of the proposed scheme. The proposed control scheme is applicable without preliminary adjustment of the control parameters.

Blood Gas Analysis↗
PubMed2001

TGF beta 2, LIF and FGF2 cooperate to induce nephrogenesis.

The metanephric kidney develops from interactions between the epithelial ureteric bud and adjacent metanephric mesenchyme, which is induced by the bud to form the epithelia of the nephron. We have found that leukemia inhibitory factor (LIF) and transforming growth factor beta 2 (TGF beta 2) are secreted by inductive rat bud cells and cooperate to enhance and accelerate renal tubule formation in uninduced rat metanephric mesenchymal explants. LIF alone or TGF beta 2 with fibroblast growth factor 2 induced numerous tubules in isolated mesenchymes over an 8 day period, while (in combination) all three caused abundant tubule formation in 72 hours. Furthermore, neutralization of Wnt ligands with antagonist-secreted Frizzled-related protein 1 abrogated these responses and combinatorial cytokine/growth factor stimulation of explants augmented nuclear activation of Tcf1/Lef1, suggesting that LIF and TGF beta 2/FGF2 cooperate to regulate nephrogenesis through a common Wnt-dependent mechanism.

Activin Receptors, Type I↗
PubMed2001

Mutational analysis of the PTEN gene in endometrial carcinoma and hyperplasia.

To determine the potential role of PTEN in the process of endometrial carcinogenesis, we examined a series of endometrial carcinoma and hyperplasia of the uterine corpus for the presence of a PTEN mutation. The entire coding region of the gene was screened for the presence of mutations by single-strand conformation polymorphism analysis, and mutations were confirmed by sequencing. We detected mutations in 14 of 57 endometrial carcinomas (13 of 50 endometrioid adenocarcinomas and 1 of 7 nonendometrioid adenocarcinomas) and 7 of 73 endometrial hyperplasias (1 of 24 simple hyperplasias without atypia, none of 16 complex hyperplasias without atypia, and 6 of 33 complex hyperplasias with atypia). Most (88%) mutations were clustered in exons 5, 7, and 8. Of the 24 mutations detected in 21 cases, 12 were frameshifts, 9 were nonsense, 2 were missense, and 1 was a silent mutation. Patients with a PTEN mutation had a better prognosis than those with no PTEN mutation. The presence of PTEN mutations in hyperplasia suggests that PTEN inactivation may occur as an initiating event in endometrial carcinogenesis and is involved in the development of cytologic atypia in hyperplasia.

Carcinoma↗
PubMed2001

Body fatness and fat distribution as predictors of metabolic abnormalities and early carotid atherosclerosis.

OBJECTIVE: To test the hypothesis that intra-abdominal fat plays a primary role over general adiposity for metabolic abnormalities and atherosclerosis. RESEARCH DESIGN AND METHODS: We cross-sectionally studied 849 Japanese men aged 50.3 +/- 8.5 years (range 20-78) with BMI 23.5 +/- 2.9 kg/m(2). Intimal-medial thickness (IMT) of the carotid artery was measured by ultrasound. General adiposity was assessed by BMI. Waist circumference and waist-to-hip ratio (WHR) were used as a surrogate measure for abdominal fat. Abdominal subcutaneous fat area (ASF) and intra-abdominal fat area (IAF) were measured by computed tomography. Correlations between these measures and carotid IMT were analyzed. The interaction of generalized adiposity (BMI) and IAF in relation to metabolic variables, such as glucose tolerance, insulin resistance, and serum lipids, was also evaluated. RESULTS: BMI, waist circumference, WHR, ASF, and IAF were all correlated with carotid IMT. Adjustment for BMI eliminated the associations between IMT and waist circumference, ASF, and IAF. In contrast, WHR retained a significant correlation with IMT. BMI and IAF were associated with insulin resistance, glucose tolerance, HDL cholesterol, and blood pressure independently of each other. IAF was an independent correlate for serum triglyceride, but BMI was not. CONCLUSIONS: The primary importance of IAF over general adiposity for carotid atherosclerosis was not confirmed. Caution is recommended when using WHR as a measure of abdominal fat. The roles of IAF for metabolic abnormalities may be more limited than conventionally thought. BMI and WHR are simple and better clinical predictors for carotid atherosclerosis versus IAF.

Abdomen↗
PubMed2001

[Brain abscess and ventriculitis associated with entrapment of the lateral ventricle appearing more like remarkable brain edema than ventricular dilatation--a case report].

We present a case with brain abscess associated with entrapment of the lateral ventricle appearing more like remarkable brain edema in the temporo-occipital lobe than ventricular dilatation. A 72-year-old man suffering from headache and vomiting visited our clinic. CT and MRI showed brain abscess in the right parieto-occipital lobe, associated with ventriculitis. Lumbar puncture also revealed purulent meningitis. Both symptoms and CSF findings improved after administration of antibiotics. The improved condition continued for two months after admission, but disturbed consciousness and left hemiparesis than appeared. MRI and CT showed entrapment of the lateral ventricle and brain edema of the right temporo-occipital region without ventricular dilatation. Because brain edema was thought to be caused by transudate of the CSF through the ventricular wall, lobectomy of the right temporal lobe and opening of the temporal horn were carried out. Although left hemiparesis and disturbed consciousness and brain edema disappeared after the operation, subdural effusion appeared. Using a subdural-peritoneal shunt, the subdural effusion was prevented and disappeared. In this case, we thought Hounsfield Unit (HU) of the brain edema caused by transudate of CSF through the ventricular wall (12.6) was markedly lower than that of so-called vasogenic edema (25.1) due to active inflammation. Measurement of the HU seemed to be a useful means to differentiate the types of brain edema in this situation from that of vasogenic edema caused by brain abscess, and thus a means for selection of the appropriate treatment.

Aged↗
PubMed2001

[The goals of the Japanese Surgical Society should not be merely for specialized surgery: they should be for general surgery, surgical education and better medical legislation].

The Japan Surgical Society (JSS) should investigate mainly general surgery, surgical education, and political approach. The Specialized surgery, which has also been studied by the JSS, should be fully evaluated in various subspecialty surgical societies, i.e. gastrointestinal, respiratory, circulatory, pediatric, and others. This is reasonable, since the board of each subspecialty has the same basic requirements as the board of the JSS and this is how the JSS and other surgical subspecialty societies can coexist. In addition, the JSS must make efforts to improve surgeons' lives overall by means of effective politics and to motivate medical students to become surgeons to prevent a scarcity, which will also contribute to the welfare of the public.

Education, Medical↗
PubMed2001

Severe hypospadias repair with meatal based paracoronal skin flap: the modified Koyanagi repair.

PURPOSE: Various techniques have been reported to repair severe hypospadias. The Koyanagi repair uses a meatal based foreskin flap. We modified this procedure and reviewed the outcome of the repair of severe hypospadias. MATERIALS AND METHODS: The modified Koyanagi repair was performed in 151 children 7 months to 15 years old (mean age 3 years) with severe hypospadias. The records of these patients were reviewed. In all cases the meatus was at or proximal to the penoscrotal junction. Followup was 6 months to 16 years (mean 6 years). Flap design is the same as in the Koyanagi repair, although our modified technique requires removal of the subcutaneous tissue of the distal portion of the flap, which acts as a full-thickness free skin graft. RESULTS: A fistula developed in 19 patients (12.6%), meatal stenosis in 3 (2%) required meatoplasty and infection in 2 (1.3%) resulted in a regressed meatal position. Good cosmetic results were achieved in all except the latter 2 cases. CONCLUSIONS: Our modified Koyanagi repair affords an excellent cosmetic appearance. The complication rate is relatively low and compares favorably with that of other techniques.

Adolescent↗
PubMed2001

[Reconstruction of the cervical esophagus using cutaneous or musculocutaneous flaps].

Reconstruction of the cervical esophagus using cutaneous or musculocutaneous flaps is described. The delto-pectoral cutaneous flap, latissimus dorsi or pectoris major musculocutaneous flap, free forearm cutaneous flap, and free rectus abdominis musculocutaneous flap are generally used for reconstruction of the cervical esophagus. Although free jejunal transfer with microsurgery is now common for reconstruction of the cervical esophagus, cutaneous or musculocutaneous flaps remain useful in high-risk patients or patients in whom free jejunal transfer or gastrointestinal reconstruction would prove incompetency due to a history of abdominal surgery or other reasons. Cutaneous or musculocutaneous flaps are also used in patients with failure of free jejunal transfer or incurable fistula after reconstruction using the stomach or colon for thoracic esophageal cancer.

Esophageal Neoplasms↗
PubMed2000

Diabetes and tumor formation in transgenic mice expressing Reg I.

To examine the effect of overexpressed regenerating gene (Reg) I on pancreatic beta-cells, we generated transgenic mice expressing Reg I in islets (Reg-Tg mice). Three lines of Reg-Tg mice were established. In line-1 Reg-Tg mice, the expression level of Reg I mRNA in islets was 7 times higher than those in lines 2 and 3 of Reg-Tg mice, and line 1 mice developed diabetes by apoptosis of beta-cells, as well as various malignant tumors. In addition to the decrease in beta-cells, compensatory islet regeneration and proliferation of ductal epithelial cells were observed in line-1 Reg-Tg mice. Because Reg I protein was secreted primarily into pancreatic ducts from acinar cells, it may primarily stimulate the proliferation of ductal epithelial cells, and not beta-cells, and their differentiation into islets. Moreover, the tumor-promoting activity of Reg I protein should be considered for its possible clinical applications.

Animals↗