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Biomedical subjects

K Nakajima

Publications and source records attributed to K Nakajima.

At least 55 records · Page 3Linked to original sources
PubMed2004

Biotransformation of chlorpropham (CIPC) in isolated rat hepatocytes and xenoestrogenic activity of CIPC and its metabolites by in vitro assays.

1: The metabolism and action of chlorpropham (isopropyl N-(3-chlorophenyl)carbamate; CIPC, a post-harvest agent) were studied in freshly isolated rat hepatocytes, and the oestrogen-like activity of CIPC and its metabolites was assessed by in vitro assays. The exposure of hepatocyte suspensions to CIPC caused concentration- (0.25-1.0 mM) and time- (0-3 h) dependent cell death, which was assessed by Trypan blue exclusion, accompanied by losses of cellular adenosine triphosphate and adenine nucleotide pools, and formation of cell bleb. 2: CIPC at a weakly toxic level (0.25 or 0.5 mM) was metabolized to isopropyl N-(3-chloro-4-hydroxyphenyl)carbamate (4OH-CIPC) and subsequently to its glucuronide and sulfate conjugates (major metabolites) or alternatively to the minor metabolites 3-chloroaniline (3CA) and 3-chloroacetanilide. CIPC (0.25 mM) added to hepatocyte suspensions was distributed equally between hepatocytes and the extracellular medium during the incubation. The glucuronide rather than the sulfate conjugate of 4OH-CIPC predominantly increased in the medium with time, while the amount of unconjugated free 4OH-CIPC in the extracellular medium increased by approximately threefold compared with the amount in the cell fraction after 0.5 h and then decreased rapidly accompanied by increases in the conjugates. This indicates that unconjugated free 4OH-CIPC produced in hepatocytes was temporarily excreted in the extracellular medium and subsequently converted to the conjugates via re-influx into hepatocytes. 3: Diethylstilbestrol (DES), bisphenol A (BPA) and 4-hydroxybenzoic acid butyl ester (butylparaben), which are known xenoestrogenic compounds, competitively displaced 17beta-oestradiol bound to the oestrogen receptor-alpha (ERalpha) in a concentration-dependent manner; IC50 values of DES, BPA, butylparaben and its derivative 3-chloro-4-hydroxybenzoic acid butyl ester (3-chloro-butylparaben) were approximately 10(-8), 10(-5), 5 x 10(-5) and 5 x 10(-4) M, respectively. In contrast, neither CIPC nor 4OH-CIPC impaired the binding of 17beta-oestradiol to ERalpha at concentrations ranging from 10(-9) to 10(-4) M, whereas at concentrations of >5 x 10(-4) M, the binding affinity of 4OH-CIPC was greater than that of CIPC. In a proliferation assay of MCF-7 cells, CIPC, 4OH-CIPC and 3CA did not increase cell numbers at concentrations ranging from 10(-9) to 10(-5) M, but these compounds at a concentration of 10(-4) M induced a considerable decrease in cell numbers relative to the control. The results suggest that even if CIPC is metabolized to 4OH-CIPC by hepatocytes, the chlorine adjacent to the 4-hydroxy group added to the intermediate as well as 3-chloro-butylparaben obstructs the appearance of oestrogen-like effects via an interaction between the intermediate and the ER.

Animals↗
PubMed2004

A systemic iridoviral disease in mullet, Mugil cephalus L., and tiger grouper, Epinephelus fuscoguttatus Forsskal: a first report and study.

A systemic iridoviral disease associated with high mortality was initially recognized in cultured mullet, Mugil cephalus L., and tiger grouper, Epinephelus fuscoguttatus Forsskal, by histopathology and transmission electron microscopy. Polymerase chain reaction was performed on tissues and viral isolates, using four published primer sets developed for the Red Sea bream iridovirus (RSIV). An indirect fluorescent antibody test was also performed on virus-infected ATCC gruntfin (GF) and seabass, Lates calcarifer Bloch, (SB) cells using a monoclonal antibody, RSIV M10. Our results suggested that the mullet and tiger grouper iridovirus bears genetic and antigenic similarities to RSIV.

Animals↗
PubMed2004

Activation of Na+-independent Mg2+ efflux by 20-hydroxyeicosatetraenoic acid in rat renal epithelial cells.

Renal epithelial cells may have Mg(2+) transport pathways that regulate intracellular free Mg(2+) concentration ([Mg(2+)](i)) and reabsorption into the body. In mag-fura 2 fluorescent measurement, extracellular Mg(2+) removal induced a Na(+)-independent [Mg(2+)](i) decrease. The [Mg(2+)](i) decrease was suppressed by methyl arachidonyl fluorophosphonate, a cytosolic and Ca(2+)-independent phospholipase A(2) (iPLA(2)) inhibitor, and bromoenol lactone, an iPLA(2) inhibitor, but it was not suppressed by a secretory phospholipase A(2) inhibitor. On the contrary, the [Mg(2+)](i) decrease was enhanced by the addition of exogenous arachidonic acid (AA). Next, we examined the effect of AA metabolite inhibitors on the [Mg(2+)](i) decrease. 17-octadecynoic acid inhibited the [Mg(2+)](i) decrease, but indomethacin and nordihydroguaiaretic acid did not. In the 17-octadecynoic acid-treated cells, 20-hydroxy-(5Z,8Z,11Z,14Z)-eicosatetraenoic acid (20-HETE) recovered the [Mg(2+)](i) decrease. Nicardipine inhibited both the basal and the 20-HETE-enhanced [Mg(2+)](i) decrease. These results suggest that 20-HETE is a key mediator in the activation of Na(+)-independent Mg(2+) efflux.

Animals↗
PubMed2004

Effects of high pressure on the solubility and growth kinetics of monoclinic lysozyme crystals.

Average growth rates of the (0 1 0) and (0 1 0) faces (R<0 1 0>) of monoclinic lysozyme crystals were measured in situ under 0.1 and 100 MPa. From the dependence of the growth rates on the lysozyme concentration, we determined the solubility of the crystal as a function of temperature at 0.1 and 100 MPa. The solubility increased with an increase in pressure. From the comparison between the growth rates under 0.1 and 100 MPa at the same supersaturation level, we found that the growth rates of the monoclinic lysozyme crystals kinetically increase with an increase in pressure. Supersaturation dependencies of the growth rates under 0.1 and 100 MPa were well fitted with a two-dimensional (2D) nucleation growth model of a birth-and-spread type. The fitting results suggest that the increase in the growth rates with pressure can be explained by the decrease in the average ledge surface energy of 2D island, the average distance between the kinks on a step and the activation energies in the incorporation processes of solute molecules.

Animals↗
PubMed2003

Novel germanium-based magnetic semiconductors.

Epitaxial synthesis and properties of novel Co and Mn-doped Ge magnetic semiconductors were studied. Epitaxial growth of high quality films with high doping concentrations has been stabilized by the use of two dopants. The magnetic and transport properties of the system exhibit high T(C) and large magnetoresistance effects that can be controlled systematically by the doping concentration. The maximum T(C) achieved in the semiconducting materials is approximately 270 K at a composition of Co0.12Mn0.03Ge0.85.

Journal Article↗
PubMed2003

Hand-assisted laparoscopic colorectal surgery using GelPort.

BACKGROUND: An easily usable hand access device will optimize success in hand-assisted laparoscopic surgery (HALS). The authors describe their initial series of HALS colorectal resections using GelPort to evaluate their current technique and results with this new device. METHODS: A retrospective study investigated 33 HALS colorectal procedures including total colectomy ( n = 16) and low anterior resection ( n = 10). All operative data, including intraoperative GelPort performance, were prospectively recorded and retrospectively analyzed. RESULTS: In this study, 3 (9.1%) of 33 HALS procedures were converted to open surgery, and 4 (13.3%) of 30 HALS procedures required minimal enlargement of incisions to facilitate extracorporeal procedures. The operative time was 263 +/- 85 min, and the blood loss was 282 +/- 148 ml. There were no device malfunctions. Three major complications (9.1%) and 7 minor wound infections (21%) were noted postoperatively. The mean hospital stay was 7.9 +/- 3.8 days. CONCLUSION: When performed with GelPort, HALS is safely and reliably applicable for various colorectal procedures.

Adult↗
PubMed2003

High-energy spin dynamics in La1.69Sr0.31NiO4.

To test the prediction that the dispersion of the magnetic resonance in superconducting YBa2Cu3O(6+x) is similar to magnons in an incommensurate antiferromagnet, we have mapped out the spin dynamics in a stripe-ordered nickelate, La(2-x)SrxNiO4, with x approximately equal to 0.31, using inelastic neutron scattering. We observe spin-wave excitations up to 80 meV emerging from the incommensurate magnetic peaks with a surprisingly large and almost isotropic spin velocity: variant Planck's over 2 pi c(s) approximately 0.32 eV A. A comparison indicates that the inferred spin-excitation spectrum is not, by itself, an adequate model for the magnetic resonance feature of the superconductor.

Journal Article↗
PubMed2003

First results from KamLAND: evidence for reactor antineutrino disappearance.

KamLAND has measured the flux of nu;(e)'s from distant nuclear reactors. We find fewer nu;(e) events than expected from standard assumptions about nu;(e) propagation at the 99.95% C.L. In a 162 ton.yr exposure the ratio of the observed inverse beta-decay events to the expected number without nu;(e) disappearance is 0.611+/-0.085(stat)+/-0.041(syst) for nu;(e) energies >3.4 MeV. In the context of two-flavor neutrino oscillations with CPT invariance, all solutions to the solar neutrino problem except for the "large mixing angle" region are excluded.

Journal Article↗
PubMed2003

Acetazolamide vasoreactivity evaluated by transcranial harmonic perfusion imaging: relationship with transcranial Doppler sonography and dynamic CT.

UNLABELLED: To establish the reliability and clinical significance of transcranial ultrasonic harmonic perfusion imaging (HPI), we evaluated HPI's relationships with transcranial Doppler (TCD) and with dynamic CT (DCT), during acetazolamide (ACZ) vasoreactivity tests. METHODS: The subjects were 12 neurological patients. Time-averaged maximum velocity (TAVMX) in the middle (MCA) and posterior cerebral arteries was measured by TCD. Time-intensity (-density) curves of HPI (DCT) after bolus intravenous contrast injections were created in 3 regions of interest (ROI) on the axial plane involving the temporal lobe, basal ganglia, and thalamus on both sides. Assessments of vasoreactivity were based on comparisons conducted before and after ACZ administration in terms of: a) relative changes (%delta) of the TCD TAVMX, b) HPI contrast area enlargement, c) %delta of calculated cerebral blood volume and flow of the HPI and DCT. RESULTS: 1) TCD vasoreactivity decrease in the left MCA tended to correlate with lower frequency of HPI contrast area enlargement on the left side. 2) HPI and DCT vasoreactivity tended to be disturbed in the same side ROIs. CONCLUSIONS: Transcranial HPI achieves repeatable non-invasive bedside evaluation of cerebrovascular reserve capacity through qualitative and quantitative measurements of brain tissue perfusion, and will have clinical value in pathophysiological follow-up and therapeutic effectiveness determination of neurointensive care patients.

Acetazolamide↗
PubMed2003

Acetazolamide vasoreactivity in persistent vegetative state and vascular dementia evaluated by transcranial harmonic perfusion imaging and Doppler sonography.

UNLABELLED: To clarify the pathophysiological differences of the cerebrovascular reserve capacity in relation to cerebral cognitive impairments between persistent vegetative state (PVS) and vascular dementia (VD), we evaluated acetazolamide (ACZ) vasoreactivity testing by transcranial harmonic perfusion imaging (HPI) and Doppler sonography (TCD). METHODS: The subjects were 11 adult patients with severe cognitive impairments (4 PVS, 7 VD). TCD mean velocity (Vm) in the middle and posterior cerebral artery (MCA, PCA) and peak intensity (PI), area under curve (AUC), and mean transit time (MTT) analyzed by HPI time-intensity curves in the bilateral temporal lobe (TL), basal ganglia (BG), and thalamus (Th) were evaluated before and after ACZ administration. Resting values and relative changes (%delta) of TCD and HPI parameters were compared between PVS and VD. RESULTS: a) Resting values: There were no significant differences between the two groups. b) Vasoreactivity: 1) PVS: %delta Vm decreased in the left PCA and MCA. %delta PI/AUC/MTT decreased in the left TL and bilateral BG. 2) VD: %delta PI/AUC decreased in the right TL. %delta MTT tended to decrease in the right side. CONCLUSION: ACZ vasoreactivity tests by transcranial HPI and TCD allowed bedside, non-invasive, quantitative evaluation of the pathophysiology of cognitive function impairment and treatments, in relation to cerebrovascular reserve capacity in PVS and VD.

Acetazolamide↗
PubMed2003

Reduction of factor XII in antiphospholipid antibody-positive patients with thrombotic events in the rheumatology clinic.

Although rheumatological diagnosis often includes an assessment of antiphospholipid (aPL) antibodies, the significance of other prothrombotic factors has not been established in thrombotic patients who are not afflicted with either arteriosclerosis or vasculitis syndrome. We have observed both the presence of antiphospholipid antibodies and a reduction of factor XII in such patients. Our results identified both lupus anticoagulant-positive (50%) and anticardiolipin antibody-positive (58%) patients. In addition, 83% of patients showed factor XII antigen level reduction. Furthermore, 70% of aPL-positive thrombotic patients showed factor XII antigen level reduction. Only two cases had antiphospholipid antibody alone, and 4/12 showed just factor XII antigen reduction. Recently, it has been reported that the presence of antiphospholipid antibodies induces factor XII reduction, and that anti-factor XII autoantibody can be detected in thrombotic patients. However, our results indicate that there are smaller factor XII reductions in non-thrombotic controls who are positive for antiphospholipid antibodies. Furthermore, anti-factor XII autoantibody was not detected in patients with decreased factor XII levels. Kindred research suggested that in two patients there was a genetic component to factor XII reduction. We concluded that the presence of both antiphospholipid antibodies and reduced serum factor XII was observed in most thrombotic patients from our rheumatology clinic. It is therefore possible to consider that the coexistence of these prothrombotic factors can contribute to the onset of thrombosis.

Adult↗
PubMed2003

Sonographic features of hepatic artery calcification in chronic renal failure.

PURPOSE: Little is known about radiological aspects of hepatic artery calcification. For this reason, the sonographic features of calcified hepatic arteries were studied in patients with chronic renal failure who frequently develop tissue calcification due to hyperparathyroidism. MATERIAL AND METHODS: Ultrasound was performed in 314 patients on dialysis who underwent examination of the liver, spleen and kidney twice in the past 4 years and were reevaluated with particular attention to acoustic shadowing. Abdominal CT was carried out in 219 of these 314 patients, and ultrasound findings were reevaluated with reference to CT findings. RESULTS: A large acoustic shadow was seen in the hilum that corresponded to the calcified hepatic artery on CT in 8 patients, and in another 9, a similar large shadow was seen in the hilum without CT confirmation. Acoustic shadows of various sizes were definitely or most likely due to arterial calcification within the liver in 36 patients. The strength of shadow depended on the angle at which the ultrasound beam hit the artery. Probable calcification of small arteries accompanying portal veins was seen in 70 patients. These changes are different from those due to pneumobilia and biliary tract diseases. CONCLUSION: Calcification of the hepatic artery can be identified by its acoustic shadow.

Aged↗
PubMed2003

Differentiation of soft tissue haemangioma by 201Tl scintigraphy.

Radiological diagnosis of deep soft tissue is often difficult. In the present study, thallium-201 ( Tl) uptake into haemangiomas and deep malignant soft tissue tumours was investigated in order to assess its clinical utility. Tl scintigraphy was reviewed in four patients presenting with soft tissue haemangiomas. Early and delayed planar images, obtained at 15 min and 3 h following the intravenous injection of Tl (111 MBq), were examined. The Tl uptake ratio was calculated by dividing the count density of the tumour region of interest (ROI) by that of the background ROI. Results were compared with those of five cases of rhabdomyosarcoma and a single instance of angiosarcoma. All haemangioma lesions demonstrated increased Tl uptake in early images. However, Tl uptake in delayed images was markedly decreased. No significant differences were observed in the early uptake ratio between haemangiomas (1.60-2.72) and reference malignant tumours (1.48-2.45); however, the difference was significant in delayed images (range, 1.01-1.26 vs. 1.43-2.03, respectively) ( P<0.02). Deep soft tissue haemangiomas revealed Tl accumulation in early images; however, a rapid washout was observed in delayed images. This distinctive feature may facilitate the use of Tl scintigraphy in the diagnosis of haemangiomas.

Adolescent↗
PubMed2003

Estimation of fractional liver uptake and blood retention of 99mTc-DTPA-galactosyl human serum albumin: an application of a simple graphical method to dynamic SPECT.

The objective of this study was to investigate clinical utility of a graphical method for estimating liver uptake and blood retention of 99mTc-DTPA-galactosyl human serum albumin (99mTc-GSA; DTPA is diethylenetriaminepentaacetic acid) using dynamic single photon emission computed tomography (SPECT) data. When considering the kinetics of 99mTc-GSA, if it is assumed that (1) 99mTc-GSA distributes only between blood and liver, and (2) no metabolism of 99mTc-GSA occurs during the observation period, a plot of liver counts versus cardiac blood pool counts should, theoretically, be a straight line. From the slope and y intercept of a regression line, coefficients for converting count based liver and blood pool data to the per cent injected dose (%ID) can be calculated. The applicability of this method was tested on dynamic SPECT data from 30 patients with liver dysfunction. To validate this method, plasma concentrations (%ID/ml plasma) at 6, 15 and 30 min after the injection were estimated by this method and compared with the measured ones. To investigate the clinical significance of the per cent liver uptake, the value obtained by this method was compared with the results of conventional liver function tests, including serum albumin, the hepaplastin test, prothrombin time and indocyanine green clearance. In every data set, a plot of liver counts to cardiac blood pool counts was fitted well by a straight line (P<0.00001). Estimated plasma concentrations by this method showed good correlation with the measured ones at 6, 15 and 30 min after the injection (r=0.748, 0.838, 0.875, respectively; P<0.0001). The liver uptake determined by this method showed good correlation with the results of conventional hepatic function tests (P<0.002). The graphical method could provide an accurate estimate of %ID of 99mTc-GSA in blood without the need for blood sampling. The liver uptake determined by this method could be a simple but useful quantitative indicator of hepatic function.

Adult↗
PubMed2003

Evaluation of left and right ventricular functional parameters with automatic edge detection program of ECG gated blood SPET.

An analysis program for ECG gated, blood pool, single photon emission tomography (SPET GBP) is available. This program permits the automatic evaluation of left and right ventricular function, but its reliability has not been thoroughly assessed. The objective of this investigation was to examine the reliability of the parameters derived from SPET GBP. Fifty-three patients who had undergone both SPET GBP and planar, ECG gated, blood pool scintigraphy (planar GBP) were enrolled in the study. Planar GBP was performed with a single-headed gamma camera. From a left anterior oblique projection, data were acquired at 24 frames/cardiac cycle with ECG gating during the equilibrium state. SPET GBP was carried out utilizing a triple-headed gamma camera, with 60 projection views over 360 degrees, with 60 s per view, in 16 frames/cardiac cycle. Left ventricular ejection fraction (LVEF) and right ventricular ejection fraction (RVEF) were calculated by using the analysis program. The reproducibility of these values and the correlation between SPET and planar GBP were assessed. To evaluate the effect of cut-off frequencies of a Butterworth filter, six different cut-off frequencies (order=8, 0.3-1.0 Nyquist) were tested with data obtained from 12 patients. The reproducibility of LVEF by SPET GBP was satisfactory (intra-observer, r=0.95; inter-observer, r=0.96), whereas reproducibility of RVEF by SPET GBP was fair (intra-observer, r=0.83; inter-observer, r=0.83). LVEF with SPET GBP was well correlated (y=1.1x+6.62, r=0.85, P<0.01) with LVEF readings of planar GBP. However, LVEF with SPET GBP was overestimated (mean difference of 12) in comparison with that of planar GBP. The RVEF derived from SPET GBP showed poor correlation (y=0.52x+33, r=0.53, P<0.01) with planar GBP. No significant effect of cut-off frequencies of Butterworth filters was evident in the calculation of LVEF and RVEF (P=0.48 and 0.67) with SPET GBP. It is concluded that SPET GBP with QBS is useful for the evaluation of LVEF. However, measurement of the RVEF showed lower reproducibility compared with measurement of the LVEF.

Adolescent↗
PubMed2003

A peptide isolated from alpha B-crystallin is a novel and potent inhibitor of platelet aggregation via dual prevention of PAR-1 and GPIb/V/IX.

BACKGROUND: The ability of low-molecular-weight heat shock protein (HSP) to modulate thrombin-induced platelet aggregation has been investigated. OBJECTIVES: We examined the inhibitory effects on platelet aggregation of nine amino acid sequences isolated from HSP20 or alpha B-crystallin and their various derivatives. METHODS AND RESULTS: Platelet aggregation induced by various agonists was performed. These findings indicated that a peptide (Trp-Ile-Arg-Arg-Pro-Phe-Phe-Pro-Phe) from alpha B-crystallin significantly inhibits platelet aggregation induced by thrombin, TRAP (a protease activated receptor-1 agonist) and botrocetin, ristocetin (a stimulator of the platelet glycoprotein Ib/V/IX-von Willebrand factor axis), but not a protease-activated receptor-4 agonist, collagen and ADP. The inhibitory activity against thrombin or botrocetin is mainly linked to Arg-Arg-Pro-Phe or Trp-Ile-Arg-Arg-Pro, respectively, among nine amino acids. Additionally, during in vivo experiments, Trp-Ile-Arg-Arg-Pro-Phe-Phe-Pro-Phe shows a significant antithrombotic effect without marked bleeding. CONCLUSION: Our results provide the basis for a potential new aspect of antiplatelet compound for the therapy of thrombosis and cardiovascular disease.

Amino Acid Sequence↗
PubMed2003

Brain lesions in the course of generalised tetanus.

A 47-year-old woman developed left hemiparesis primarily affecting the lower limbs during the course of severe generalised tetanus. MRI on the 82nd hospital day revealed cortical and subcortical lesions predominantly in the right frontal and parietal lobes in addition to marked brain atrophy. Three months later, the enhancing lesions were still present on follow up MRI. We postulate that structures above brainstem may be involved in severe generalised tetanus.

Atrophy↗