Biomedical subjects

K Hayakawa

Publications and source records attributed to K Hayakawa.

At least 37 records · Page 2Linked to original sources

PubMed2001

Dynamic reorientation of cultured cells and stress fibers under mechanical stress from periodic stretching.

Cell lines derived from rat aorta and frog kidney were cultured on elastic membrane, and mechanical stress was given to the cells by stretching the membrane periodically. Cell reorientation oblique to the direction of stretching occurred as a result of the rapid withdrawal of cell periphery located along the direction of stretching and gradual extension of the cell membrane toward the direction oblique to the direction of stretching. Dynamic reorganization of stress fibers in living cells was visualized by labeling stress fibers with TRITC(3)-actin or EGFP-tagged moesin fragments with actin-binding ability. Stress fibers aligned in the direction of stretching disappeared soon after the start of stretching and then obliquely reoriented stress fibers appeared. The stretch-induced reorientation of cultured cells was suppressed by an inhibitor of stretch-activated (SA) cation channels and by a Ca(2+) chelator. However, the rearrangement of stress fibers was not affected by these agents. From these results, we suggest that Ca(2+) influx via SA channels is involved in stretch-induced cell reorientation but stress fiber rearrangement is independent of SA channels. Therefore, cell reorientation does not simply depend on the arrangement of stress fibers but may be controlled by some additional mechanism(s) which is regulated by calcium signaling.

Actins↗

PubMed2001

Protein determination by high-performance gel-permeation chromatography: applications to human pancreatic juice, human bile and tissue homogenate.

A high-performance gel-permeation chromatography (HPGPC) method to determine the proteins of human pancreatic juice, bile, and tissue homogenate has been developed. A diol-type silica gel column (35 x 8 mm I.D., 5 nm average pore diameter) was used under a column temperature of 8 degrees C. The eluent was acidic phosphate buffer with a high concentration of sodium chloride, nonionic detergent of polyoxyethylene (20) cetyl ether (Brij 58), glycerol and 2-propanol. The UV wavelength used for the protein detection was 210 nm. Analytical time was within 3.5 min. Good correlation coefficients were obtained with this HPLC method at a column temperature of 8 degrees C and a spectrophotometric bicinchoninic acid (BCA) method. A photometric pyrogallol-red molybdate complex method was found to correlate well with this HPLC method and with the BCA method only for tissue homogenate. Since this HPGPC protein assay method is simple, convenient, rapid, reproducible, and reliable, it is expected to be generally applicable to clinical and also to biochemical research.

Animals↗

PubMed2001

Multi-beam polarized photometric detector for high-performance liquid chromatography.

A novel multi-beam polarized photometric detector (PPD) for high-performance liquid chromatography (HPLC) is described. By pairing a polarizing prism with a thin quartz plate as a retarder, many linear polarized beams are produced at every 1/2 wavelength of the plate, and the polarizing axes of the adjacent beams intersect each other. The addition of another prism inclining its polarizing axis by pi/4 against the first one enables the simultaneous measurement of optical rotations based on the PPD at many wavelengths. The combination of these optics with a photo-diode array detector can be used to construct a modulated type polarimeter. This detector is designed to measure the optical rotation of an analyte at its absorption band. The spline function connecting the points at 1/4 wavelengths of the plate was used as a baseline to extract the PPD waves. The use of the similarity factor as a noise filter gave high sensitivity. Application of the proposed technique to an analyte carrying the Cotton absorption band provided good results.

Chromatography, High Pressure Liquid↗

PubMed2001

Sb K-edge absorption fine structure of Sb2Te3.

In order to study the local structure of some antimony compounds, Sb K-edge XAFS spectra were measured for Sb2Te3 and InSb. The measurements were performed in the transmission mode at BL-01 of SPring-8. Though crystal structure of antimony telluride Sb2Te3 is known by X-ray diffraction analysis, the EXAFS analyses give controversial result on the Sb-Te distance and the coordination number of Sb2Te3. Comparing the observed XANES spectra for Sb2Te3 with FEFF8 calculation, we can explain the controversial results which are also supported by the observed X-ray powder diffraction.

Journal Article↗

PubMed2001

Multiple scattering approach to K-edge XANES of Sb-Te systems.

The Sb-Te systems are important for optical memories. The local structures of these Sb-Te systems are crucial to understand the properties. Here we study three different Sb-Te systems, Sb2Te3, c- and a-SbTe (c; crystalline, a; amorphous) by use of XANES analyses. The present calculations for Sb2Te3 system show quite good agreement with the observed spectra. In contrast to Sb2Te3 system, both c- and a-SbTe systems, in which a ratio of Sb to Te is 3, are metastable; both of the structures have not been known yet. We thus investigate these local structures by use of the multiple scattering approach, and propose a possible model for each of c- and a-SbTe.

Journal Article↗

PubMed2001

Direct chiral resolution of malic acid in apple juice by ligand-exchange capillary electrophoresis using copper(II)-L-tartaric acid as a chiral selector.

Chiral resolution of native DL-malic acid was achieved by ligand-exchange capillary electrophoresis using copper(II)-L-tartrate as a chiral selector. Factors affecting chiral resolution, migration time, and peak area of malic acid were studied. The running conditions for optimum separation of malic acid were found to be 1 mM copper(II) sulfate-1 mM L-tartrate (pH 5.1) with an effective voltage of -20 kV at 30 degrees C, using direct detection at 280 nm, and resolution (Rs) of racemic malic acid was approximately 4. With this system, D- and L-malic acids in apple juice were analyzed successfully.

Beverages↗

PubMed2001

Identification of reaction products of methamphetamine and hydrogen peroxide in hair dye and decolorant treatments by high-performance liquid chromatography/mass spectrometry.

The effect of hydrogen peroxide, a main component of hair dye and decolorant treatments, on methamphetamine (MA) was studied. Two analytical methods, thin-layer chromatography (TLC) and high-performance liquid chromatography/mass spectrometry (LC/MS), were used for the separation and identification of MA derivatives. Mixtures of MA solutions and hydrogen peroxide that had been incubated at 39 degrees C for 24 h were shown to contain para-hydroxy MA by TLC and para-, meta- and ortho-hydroxy MAs by LC/MS. In addition, MA N-oxide and N-hydroxy MA were found in MA/hydrogen peroxide mixtures immediately after mixing. Therefore, we concluded that MA changed to MA N-oxide and N-hydroxy MA before changing to para-, meta- and ortho-hydroxy MAs.

Chromatography, High Pressure Liquid↗

PubMed2001

Transient seizure activity demonstrated by Tc-99m HMPAO SPECT and diffusion-weighted MR imaging.

Cerebral perfusion single photon emission computed tomography (SPECT) has been used to confirm the localization of the epileptic focus and the evaluation of seizure. Recently, diffusion-weighted MR imaging (DWI) has been recognized for evaluation of seizure activity. We describe a case of transient seizure activity demonstrated by Tc-99m HMPAO SPECT and DWI. This patient was a 61-year-old woman with a 10-month history of right middle cerebral artery (MCA) infarction who had a generalized seizure during MRI. DWI immediately after seizure showed transient hyperintensity in the right frontal gray matter and the white matter, and these apparent diffusion coefficients (ADC) were transiently decreased. This transient hyperintensity on DWI corresponded to transient hyperperfusion identifying the epileptic focus on interictal Tc-99m HMPAO SPECT. Transient sustained seizure activity might cause these changes on DWI and SPECT. It was considered that interictal Tc-99m HMPAO SPECT showed the delayed hyperperfusion caused by excitatory neuronal overaction and DWI showed cytotoxic edema seizure-induced by energy failure of the membrane-bound Na/K-ATPase pump.

Cerebral Infarction↗

PubMed2001

Interictal crossed cerebellar hyperperfusion on Tc-99m ECD SPECT.

Crossed cerebellar hyperperfusion (CCH) in epilepsy is a rare condition that is observed on ictal cerebral perfusion SPECT. The mechanism of CCH assumes that hyperperfusion in the epileptic foci of the unilateral supratentorium causes hyperperfusion secondary to the corticopontocerebellar pathway (CPCP)-mediated remote effect in the contralateral cerebellar hemisphere. This phenomenon is similar to that of crossed cerebellar diaschisis (CCD). In this report we demonstrated interictal CCH in a patient with epilepsy in technetium-99m-ethyl cysteinate dimer (Tc-99m ECD) SPECT of the brain. To the best of our knowledge, interictal CCH has not been reported in the literature. This is the first report to describe the phenomenon with interictal Tc-99m ECD SPECT.

Aged↗

PubMed2001

Bilateral crossed cerebello-cerebral diaschisis and mutism after surgery for cerebellar medulloblastoma.

A 7-year-old boy developed mutism after surgery for cerebellar medulloblastoma. Postoperative magnetic resonance imaging (MRI) showed atrophy of the cerebellar vermis and both cerebellar hemispheres, predominantly on the right side. Single photon emission computed tomography (SPECT) with technetium-99m-ethyl cysteinate dimer (Tc-99m ECD) revealed decreased cerebral blood flow (CBF) in the bilateral thalami, bilateral medial frontal lobes, and left temporal lobe in addition to the cerebellar vermis and both cerebellar hemispheres when mutism was manifest, indicating the existence of bilateral crossed cerebello-cerebral diaschisis (BCCCD). Circulatory disturbance in both cerebellar hemispheres secondary to tumor resection probably caused BCCCD in both cerebral hemispheres, predominantly in the left, via the dentatothalamocortical pathway (DTCP). With recovery of his mutism, CBF increased in the right thalamus, bilateral medial frontal lobes and left temporal lobe. Thus BCCCD was improved, with only a slight decrease in CBF still persisting in the left thalamus. The mechanism of mutism may have involved damage to the cerebellar vermis (the site of incision at operation), the left dentate nucleus (heavily infiltrated by the tumor) and the right dentate nucleus of the cerebellum (affected by circulatory disturbance secondary to acute postoperative edema). The SPECT findings suggested that mutism was associated with BCCCD-induced cerebral circulatory and metabolic hypofunction in the supplementary motor area mediated via the DTCP.

Cerebellar Neoplasms↗

PubMed2001

Interesting RI accumulation in hepatic images with Tc-99m GSA SPECT scintigraphy in idiopathic portal hypertension.

The authors report a case of idiopathic portal hypertension (IPH), which showed interesting RI accumulation on Single Photon Emission CT (SPECT) images, with Tc-99m galactosyl human serum albumin (GSA) scintigraphy. Accumulation of Tc-99m GSA was decreased in the periphery of the liver where strong enhancement was revealed only in the arterial phase on dynamic CT. These findings imply that portal flow is decreased in the periphery of the liver where arterial flow is dominant. It was thought that secondary reduced activity of GSA due to a decrease in portal flow results in reduced radioactivity in the periphery of the liver in IPH. This interesting accumulation of Tc-99m GSA may be one of the sign of IPH.

Aged↗

PubMed2001

Treatment of ruptured hepatocellular carcinoma.

BACKGROUND: The problem of whether surgical or conservative treatment is indicated for ruptured hepatocellular carcinoma (HCC) has not been analyzed from the viewpoint of long-term development of hepatitis viral infection from liver fibrosis to liver cirrhosis. Although transcatheter arterial embolization (TAE) for hemostasis followed by two-stage hepatectomy has been established as the best treatment for ruptured HCC, there still remain difficulties in the treatment of some patients. METHODS: Twelve patients with ruptured HCC who were surgically or conservatively treated were retrospectively analyzed in terms of modality of treatment, liver function, extension of HCC, complications, survival rate, and cause of death. RESULTS: Tumor rupture can occur either in the early phase or in the terminal phase during the development from liver fibrosis to liver cirrhosis, while tumor rupture occurs at the advanced stage in terms of HCC extension. TAE for emergent hemostasis or prevention of re-bleeding was performed in ten patients, while TAE was contraindicated in one patient and emergent laparotomy for hemostasis was performed in one patient. In four patients, elective extended surgical resection was performed, because liver function was evaluated as clinical stage 1 according to the General rules for the clinical and pathological study of primary liver cancer of the Liver Cancer Study Group of Japan. In seven patients, conservative or medical treatment was selected, because liver function was evaluated as poor. The surgically treated group, who could tolerate extensive operation, survived longer than the conservatively treated group. CONCLUSIONS: While TAE remains the best method to employ for hemostasis, it still has limitations. Hence, we should be mindful of other possible modalities for hemostasis and their outcomes. Rupture of HCC at an early phase in the development of liver fibrosis is a good indication for elective surgical treatment and should be distinguished from rupture in the terminal phase of liver cirrhosis, which should be treated conservatively. Although elective surgical treatment can be performed in selected patients, tumor size and location of HCC, in addition to liver function, should be taken into consideration.

Aged↗

PubMed2001

Detection of IL-2 receptor gene expression in peripheral blood from renal transplant patients.

Cytokine monitoring is a potentially useful tool in the management of transplant patients. This study was conducted to analyze interleukin (IL)-1, tumor necrosis factor (TNF), IL-2, and IL-2 receptor gene expression by reverse transcriptase-polymerase chain reaction (RT-PCR) in peripheral whole blood from healthy volunteers and patients who underwent laparotomy or renal transplantation. In the patients who underwent laparotomy, IL-1 and TNF expression was detected postoperatively, but IL-2 and IL-2 receptor expression was not. IL-1, TNF, and IL-2 receptor gene expression was detected in all the renal transplant patients, including those with signs of rejection. No cytokine gene expression was detected preoperatively, pretransplant, or in the healthy volunteers. We were able to discriminate transplantation from laparotomy by the cytokine profile. These results indicate that our method may be a useful tool for the immunological monitoring of transplant patients.

Adult↗

PubMed2001

Dynamic process of apoptosis in adult rat cardiomyocytes analyzed using 48-hour videomicroscopy and electron microscopy: beating and rate are associated with the apoptotic process.

Dynamic process of apoptosis has not been elucidated in adult rat cardiomyocytes. Soluble Fas ligand (0.1 microg/ml) in the presence of actinomycin D (0.05 microg/ml) induced apoptosis in cultured adult rat cardiomyocytes, as documented by activated caspase-3, DNA fragmentation, and apoptotic ultrastructure. In the present model, we observed 60 adult cardiomyocytes with a normal rod shape under a real-time videomicroscope continuously for 48 hours. Seventeen cells (28%) were unchanged and 7 cells (12%) showed oncosis (so-called necrosis) in which no beating was evident. In the remaining 36 cells (apoptosis, 60%), a slow beating (17 +/- 3/min) was initiated 16 +/- 1 hours later. Approximately 1 hour later, the rod cells showed long-axial shortening as bone- or club-like, or square-shaped, accompanied with faster beating rates (35 +/- 7/min). In 29 cells (type A1 and A2), marked shrinkage occurred; the cellular shape became almost completely round with a smooth surface and the beating ceased 3.0 +/- 0.4 hours later. Then, smooth budding appeared 0.6 +/- 0.2 hours later. Apoptotic bodies were found in 8 cells 10 +/- 4 hours later (type A1, 13%) but not in 21 cells (type A2, 35%). In the other 7 cells (type A3, 12%), the cell surface became rough 8 +/- 3 hours later and the beating ceased. Maximal beating rate was greatest in type A1 (72 +/- 26/min) and greater in type A2 (29 +/- 5/min) than in type A3 (10 +/- 2/min). Electron microscopy confirmed apoptotic ultrastructure even in the cardiomyocytes with bone-, club-like, or square shapes, suggesting that type A3 as well as A1 and A2 is also under apoptotic process. A caspase inhibitor, zVAD.fmk, blocked beating, apoptotic morphology, and DNA fragmentation, indicating these depended on caspase activation. In the caspase-dependent apoptotic process of cultured adult cardiomyocytes, beating and the following deformity of the cellular edges were the initial signs and the rate of beating was related with the subsequent three different processes of apoptosis.

Animals↗

PubMed2001

Determination of nitroarenes in precipitation collected in Kanazawa, Japan.

Eight nitroarenes, 1,3-, 1,6- and 1,8-dinitropyrenes, 1-, 2- and 4-nitropyrenes, 6-nitrochrysene and 2-nitrofluoranthene, in precipitation collected in Kanazawa were determined. The nitroarenes in the precipitation were concentrated onto solid phase extraction cartridges, and identified with high-performance liquid chromatography with chemiluminescence detection. The nitroarene concentrations in the precipitation were in the range 0.016-15 pmol/L, and the nitroarene composition tended to be the same as that in airborne particulates. 1-Nitropyrene in river water and seawater were also determined. 1-nitropyrene concentrations on the days after rain (19-110 fmol/L) were higher than those on the days before rain (4,11 fmol/L). Moreover, 1-nitropyrene concentrations in the river water were much lower than those in the precipitation, but were higher than those in the seawater. These results suggested that the nitroarenes in the precipitation and the river water came from airborne particulates.

Air Pollutants↗

PubMed2001

High-dose radiation therapy for elderly patients with inoperable or unresectable non-small cell lung cancer.

PURPOSE: To evaluate definitive radiation therapy delivering doses in excess of 60 Gy for elderly patients aged 75 years or over with non-small cell lung cancer (NSCLC). MATERIALS AND METHODS: The treatment results for 97 patients aged 75 years or older (mean age 78 years; elderly group) with inoperable or unresectable NSCLC were retrospectively analyzed and compared with those for 206 patients younger than 75 year old (mean age 64 years; younger group). The elderly patients were classified into two groups; 67 patients aged 75-79 years (the elderly A) and 30 patients aged 80 years or older (the elderly B). Most of all patients were treated with a total dose of 60 Gy or more in 2 Gy daily standard fractionation. RESULTS: The overall 2 and 5 year survival rates were 32 and 13% for the elderly A group, and 28 and 4% for the elderly B group, respectively, compared with 36 and 12% for the younger group. There was not a statistically significant difference in survival rates among three groups. In stage I-II NSCLC patients there was also no significant difference in survival curves among the three groups. In patients with stage III disease, however, the survival curve of the elderly B was inferior to those of the younger group and the elderly A group, although the difference was not statistically significant. After the treatment the deterioration rate of the performance status was only 5% in the younger group and 8% in the elderly group. Only three younger and two elderly patients died of late pulmonary insufficiency associated with high-dose irradiation to the proximal bronchus. No other treatment-related event was observed except for mild acceptable acute complications in the elderly groups. CONCLUSIONS: Definitive radiation therapy is recommended to the elderly aged 75 years or older with inoperable or unresectable NSCLC, especially early stage disease, as an acceptable choice of treatment.

Aged↗

PubMed2001

Surgical treatment for an idiopathic renal arteriovenous fistula with a large aneurysm.

Interventional embolization is currently the first line treatment for arteriovenous fistulas; however, the efficacy of repeated embolization remains controversial. A case is reported of an idiopathic renal arteriovenous fistula with large aneurysmal dilatation treated by surgery following the failure of interventional embolization. A 42-year-old woman was admitted to Ichikawa General Hospital, Japan, with gross hematuria containing many clots. Right renal arteriogram showed an aberrant vessel arising from the main trunk of the renal artery, which was followed by the formation of an aneurysm and rapidly ended in arteriovenous shunting. The aneurysm was approximately 35 mm in size. As interventional embolization had failed, surgical treatment including extracorporeal renal surgery was performed. Postoperative renal angiography revealed excellent renal function and beautiful vascular architecture. Although the indication for surgical treatment of renal vascular disease has decreased owing to the advancement of interventional techniques, there are still some risky cases for which surgical repair should be recommended.

Adult↗

PubMed2001

Body mass index for chronic hemodialysis patients: stable hemodialysis and mortality.

Body mass index (BMI) is used as a reference for weight control programs in the general population and in morbidity and mortality studies in diabetes patients. However, the implications of BMI in chronic hemodialysis patients is unclear. We studied the BMI of chronic hemodialysis patients, focusing on problems encountered during outpatient hemodialysis therapy and on 2-year mortality. Outpatients with chronic hemodialysis (n = 258; 144 men, 114 women) were divided into four groups: (i) patients with stable hemodialysis; (ii) patients with marked hypotension requiring catecholamine infusion during hemodialysis; (iii) patients with excessive interdialysis weight gain requiring occasional additional hemodialysis; and (iv) patients with troublesome hemodialysis due to other causes. The statistical differences between the average BMI among these groups were evaluated, and were subdivided into sex, age and the duration of hemodialysis history. The 2-year mortality rates of these patients were also studied according to their BMI. In patients under 60 years of age, those with excessive interdialysis weight gain had statistically larger BMI (23.2; n = 35) compared to patients with good hemodialysis control (20.1; n = 178), regardless of gender and hemodialysis history. The mortality rate was at a minimum at approximately 20 BMI in patients under 60 years of age. However, lower BMI was associated with a greater mortality rate in patients 60 years or over. For chronic hemodialysis patients, the BMI associated with stable hemodialysis and minimum mortality is approximately 20, in those under 60 years of age. The BMI of aged hemodialysis patients should be considered separately in morbidity and mortality studies.

Body Mass Index↗