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Biomedical subjects

R Kojima

Publications and source records attributed to R Kojima.

At least 55 records · Page 3Linked to original sources
PubMed1994

The status of pacemaker implantations in Japan.

It has been over 40 years since the initial clinical application of a cardiac pacemaker. Currently, approximately 300 per million patients in the United States and Europe are kept alive owing to the benefit of implantable pacemakers. Recently, the Japanese Cardiac Pacing Society and the Japanese Society of Artificial Organs performed pacemaker registry studies for 1989 and 1990. In this paper, results of this survey are described. Currently, implantable cardiac pacemakers are utilized only on the level of 120 per million patients in Japan. Surprisingly, all implantations were performed using foreign manufactured pacemakers. Despite the high level of electronic technologies available in Japan, no Japanese-made implantable cardiac pacemakers are utilized in Japan. One could speculate that a major reason for the low level of clinical application of cardiac pacemakers is that these devices are quite expensive because of the import duties imposed on them. It is necessary and strongly recommended that implantable cardiac pacemakers be manufactured in Japan in order for them to be utilized as fully as they are in the United States and Europe.

Adolescent↗
PubMed1994

Molecular characterization of ROSIT, a renal osmotic stress-induced Na(+)-Cl(-)-organic solute cotransporter.

A gene family encoding many Na(+)- and Cl(-)-dependent organic solute cotransporters has recently been recognized. Among the cotransporters that have been characterized are those for neurotransmitters, amino acids, and organic osmolytes. Using polymerase chain reaction and mRNA derived from renal cortex, we isolated a new member of this gene family, ROSIT, a renal osmotic stress-induced transporter. The cDNA is 2,354 bp long with an open reading frame of 1,845 bp. The 615 deduced amino sequence shows ROSIT to be most clearly related to two orphan cDNAs of this family isolated from brain. Northern analysis showed the mRNA is normally expressed in renal cortex but not in brain, heart, colon, liver, stomach, or skeletal muscle. Moreover, hypernatremic rats displayed a marked increase in mRNA levels in renal cortex, renal outer medulla, and perhaps intestine. Heterologous expression of the cRNA in Xenopus laevis oocytes failed to reveal the function of this gene product when analyzed with isotope fluxes or electrophysiological measurements using a wide variety of organic solutes. Although its function remains unknown, ROSIT is likely to be involved in kidney reclamation of an organic osmolyte or osmolyte precursor required for adaptation to hypertonic stress.

Amino Acid Sequence↗
PubMed1994

Marked antinephritic action and less adverse effects of methylprednisolone suleptanate by intermittent administration in rats.

To establish the regimen for beneficial prolonged treatment with glucocorticoids on nephritis, we investigated the antinephritic effect of methylprednisolone suleptanate (MPS) and its influence on adrenal function by intermittent administration (IA) in comparison with daily administration (DA) in crescentic-type anti-GBM nephritic rats. In IA, MPS (0.25, 1.0 and 3.0 mg/kg) was injected for 3 successive days followed by a 3-day withdrawal during a 40-day period. MPS inhibited the elevation of urinary protein and serum cholesterol and glomerular alterations by both IA and DA. The effect of MPS on these parameters was more potent by IA than by DA. MPS significantly suppressed the increment of the number of ED-1(+) cells and TH-1(+) cells in nephritic glomeruli. DA, but not IA, caused atrophy of the adrenal glands. IA prevented the remarkable decrease in corticosterone level provoked in nephritic rats. In conclusion, for the treatment of nephritis, IA seems to be a better regimen for the administration of MPS. MPS may exert an antinephritic action by inhibiting mesangial cell proliferation and infiltration of monocytes/macrophages into glomeruli in addition inhibiting antibody production.

Adrenal Glands↗
PubMed1993

Thyroid hormone affects the gene expression of retinoid X receptors in the adult rat.

Gene expression of three nuclear retinoid X receptors (RXR alpha, beta and gamma) was examined by Northern blot analysis in various rat tissues. The RXR alpha mRNA (5.5 kb) was detected in most tissues and particularly expressed at a high level in the liver. The RXR beta transcripts (2.4 and 3.0 kb) were expressed ubiquitously, and particularly at high levels in the brain and testis. In the liver, heart, kidney and lung, the RXR gamma mRNA (2.0 kb) was specifically detected. Furthermore, we examined the effect of retinoid, vitamin D and thyroid hormone status on the gene expression of RXR alpha, beta and gamma. Though retinoid and vitamin D did not affect the mRNA levels of three RXRs, the mRNA levels of two genes were controlled by thyroid hormone. Namely, positive (RXR beta) and negative (RXR gamma) regulations by thyroid hormone were observed with no effect on the gene expression of RXR alpha. These results suggest that thyroid hormone might affect the signal transduction of retinoid, vitamin D and thyroid hormone by changing RXR levels.

Animals↗
PubMed1993

Effect of reperfusion by direct percutaneous transluminal coronary angioplasty on ventricular late potentials in cases of total coronary occlusion at initial coronary arteriography.

The relationship between the time required for reperfusion and the incidence of late potentials was studied in 94 patients who survived a first acute myocardial infarction (AMI) and who showed total occlusion of the infarct-related artery at an initial coronary arteriography. Sixty-three patients who successfully underwent direct percutaneous transluminal coronary angioplasty (PTCA), and 31 who were treated conventionally (controls), underwent signal-averaged electrocardiography. Direct PTCA patients were classified into 5 groups according to the time required for reperfusion: < or = 4, 4-6, 6-8, 8-10, and > or = 10 h. The incidence of late potentials in these groups was 8%, 12%, 14%, 33%, and 43%, respectively, and 48% in the controls. Late potentials were recorded more frequently as the period until successful reperfusion increased: the incidence of late potentials was significantly lower in the < or = 4 and 4-6 h groups than in the controls (p < 0.005 and p < 0.05, respectively). Therefore, reperfusion achieved within 6 h reduced the incidence of late potentials in AMI patients and may be effective for preventing malignant ventricular arrhythmias.

Acute Disease↗
PubMed1993

Gene expression of cellular retinol-binding protein I (CRBP I) is affected by dietary proteins in the rat liver.

The effect of dietary proteins and vitamin A status on the gene expression of cellular retinol-binding protein I (CRBP I) was studied in the rat liver. The gene expression was estimated as amounts of transcript (mRNA) by Northern blot analysis using rat CRBP I cDNA. Though vitamin A status is known to positively regulate the gene expression of CRBP I in the extrahepatic tissues, in the present study we observed that the amount of the CRBP I transcript in liver was neither reduced by vitamin A-deficiency, nor affected by replenishment with an excess dose of all-trans retinoic acid. These results indicate that in the liver, different from the extrahepatic tissues, the gene expression of CRBP I may not be controlled by vitamin A. However, when the rats were fed on the diets that differed in dietary proteins, the gene expression of CRBP I in liver was enhanced by higher quality and quantity of dietary proteins, though no effect of dietary proteins was observed upon the hepatic contents of retinol. The concentrations of serum retinol were almost proportional to the mRNA levels of CRBP I. In contrast, the hepatic gene expression of another retinol-binding protein, RBP, and one subtype of retinoic acid receptor, RAR alpha was not influenced in the nutritional condition tested here. Our findings suggest that the gene expression of CRBP I in liver may be under control of the intake of dietary proteins. Thus, it is likely that in the light of the function of CRBP I on cellular transport and metabolism of retinol, dietary proteins may affect the actions of vitamin A in the extrahepatic tissues through changing the amounts of CRBP I in liver.

Animals↗
PubMed1993

Pulmonary carcinoma associated with hamartoma in an 11-year-old boy.

PURPOSE: We describe a poorly differentiated adenocarcinoma of the lung in an 11-year-old boy who had had a pulmonary hamartoma for at least 8 years. CONCLUSIONS: A hamartoma, even if clinically silent, may lead to the development of malignant tumors on rare occasions.

Adenocarcinoma↗
PubMed1992

Effect of retinoid status on alpha, beta and gamma retinoic acid receptor mRNA levels in various rat tissues.

We have investigated the effects of retinoids, vitamin D and thyroid hormone on the levels of retinoic acid receptor (RAR)alpha, RAR beta and RAR gamma mRNAs in intact animals. Although vitamin A deficiency caused no significant changes in the levels of RAR alpha and RAR gamma mRNAs, the level of RAR beta transcripts was greatly decreased in various tissues of vitamin A-deficient rats, but was restored rapidly to a normal level after administration of retinoic acid. Retinol also restored the RAR beta mRNA level, but the magnitude and kinetics of the induction differed from those by retinoic acid. The use of specific inhibitors demonstrated that this autoregulation of RAR beta gene expression in vivo occurred at the transcriptional level. In addition, from these results it was postulated that the maintenance of the normal RAR beta mRNA levels seemed to require a threshold serum retinol concentration (about 25 micrograms/dl). Moreover, we found that administration of retinol and retinoic acid to normal rats caused the overexpression of RAR beta transcripts (2-15-fold) when compared with the control levels of RAR beta mRNA, although the levels of RAR alpha and RAR gamma mRNAs were not affected. Vitamin D and thyroid hormone did not modulate the levels of RAR transcripts. These findings clearly indicate the specific ligand regulation of RAR beta gene expression in intact animals. The altered levels of RAR beta according to retinoid status may affect retinoid-inducible gene expression.

Animals↗
PubMed1992

Suppression by cyclosporin A of anti-GBM nephritis in rats.

The suppressive effect of cyclosporin A (CyA) on the development of glomerulonephritis was evaluated in rats with either original- or crescentic-type anti-glomerular basement membrane (GBM) nephritis. CyA (2.5, 10 or 20 mg/kg) was given p.o. daily to original-type anti-GBM nephritic rats for 10 days from the day after the injection of anti-GBM serum. The development of the nephritis was dose-dependently suppressed by CyA before the production of specific antibody against rabbit gamma-globulin (the heterologous phase). In addition, CyA suppressed glomerular infiltration of leukocyte subsets (leukocyte with common antigen, T cell, helper T cell, suppressor/cytotoxic T cell, macrophage/monocyte). CyA was given p.o. daily to crescentic-type anti-GBM nephritic rats for 10 days from the 10th day after the injection of anti-GBM serum. CyA-administration caused a distinct suppression of the deterioration of nephritis during the autologous phase. In addition, CyA markedly suppressed the antibody production. The above data indicate that CyA has a beneficial effect on anti-GBM nephritis, and the antinephritic action of this agent may be due to the inhibition of glomerular infiltration of leukocyte subsets as well as the suppression of the antibody production.

Acetylglucosaminidase↗
PubMed1992

Preventive actions of N-(3-aminopropionyl)-L-histidinato zinc (Z-103) through increases in the activities of oxygen-derived free radical scavenging enzymes in the gastric mucosa on ethanol-induced gastric mucosal damage in rats.

Z-103 at 1 to 25 mg/kg, p.o. prevented 100% ethanol-induced gastric mucosal lesions in a dose-dependent manner. Z-103 at 3 to 25 mg/kg, p.o. significantly elevated gastric mucosal superoxide dismutase (SOD)-like activity 1 hr after its administration to normal rats. In addition, Z-103 at doses (10 and 25 mg/kg, p.o.) which prevented 100% ethanol-induced gastric lesion further increased gastric mucosal SOD-like and glutathione peroxidase (GSH-px) activities elevated by 60% ethanol. Z-103 (10 and 25 mg/kg) significantly inhibited the increase in thiobarbituric acid-reactive substances in gastric mucosa injured by 60% ethanol. The combination with cycloheximide, a protein synthesis inhibitor, completely abolished the prevention of 60% ethanol-induced gastric mucosal lesions and the elevation of both free radical scavenging enzyme activities in the mucosa by Z-103 (10 mg/kg, p.o.). These results suggest that Z-103 may partly protect rat gastric mucosa against ethanol-induced damage by scavenging oxygen-derived free radicals via increases in the synthesis of SOD-like and GSH-px enzymes in the mucosa.

Administration, Oral↗
PubMed1992

[Detection of ventricular late potentials comparison of 4 commercial high-resolution systems].

UNLABELLED: The purpose of this study was to evaluate the methodologic problems of noninvasive registration of ventricular late potentials. METHODS: we compared the results obtained in the same patients with four different systems which were Marquette MAC1, MAC12, ART LP101 and FUKUDA VCM 3000. Filtering was employed digital forward direction, 100-300 Hz in MAC1, digital FFT, 40-250 Hz in MAC12, digital, bidirectional, 40-250 Hz in ART and analogue, forward direction 40-300 Hz in FUKUDA VCM 3000. DEFINITION OF LATE POTENTIALS (LPs): Filtered QRS duration (FQRSD) was 120 msec or more, root mean square voltage in the last 40 msec (RMSV) was 15 microV or less in MAC12 and ART. FQRSD was 130 msec or more, RMSV was 15 microV or less in FUKUDA. FQRSD was 20 msec or more after QRS obtained from low resolution leads in MAC1. SUBJECTS: 163 patients [control 13, PVCs 23, myocardial infarction 55, others 51, IVCD (RBBB, LBBB, IVCD) 21] were included in this study. RESULTS: 17.6% of all patients (except for IVCD) showed LPs with MAC12, 20.0% with ART, 30.3% with FUKUDA, and 14.1% with MAC1. 23.1% of the control group showed LPs with MAC12 and FUKUDA, but no cases showed LPs with ART and FUKUDA. 4.3% of the PVC group showed LPs with MAC12, 13.0% with ART and FUKUDA, but no cases showed LPs with MAC1. 25.5% of the myocardial infarction group showed LPs with MAC12 and MAC1, 30.9% with ART and 36.3% with FUKUDA. All four methods gave corresponding results in 65.4% of patients, 7.0% positive and 58.4% negative findings. FQRSD of MAC12, ART and FUKUDA was 110.2 +/- 18.1 msec, 105.2 +/- 20.4 msec and 125.8 +/- 22.8 msec respectively. Correlation coefficient (r value) in FQRSD was 0.90 between ART and MAC12, 0.74 between ART and FUKUDA, and 0.75 between FUKUDA and MAC12. RMSV of MAC12, ART and FUKUDA was 49.2 +/- 30.2 microV, 43.7 +/- 37.8 microV and 22.5 +/- 10.6 microV respectively. R value in RMSV was 0.59 between ART and MAC12, 0.38 between ART and FUKUDA and 0.43 between FUKUDA and MAC12. R value in high frequency low amplitude signals duration under 40 microV of LPs positive patients in MAC1 was 0.51 between ART and MAC 12, 0.18 between MAC12 and MAC1, and 0.32 between ART and MAC1. Most of the differences result from a different interpretation of the tracings. Especially LPs far from QRS offset could be registered with neither MAC12, ART nor FUKUDA.

Action Potentials↗
PubMed1991

Acute spinal cord injury: magnetic resonance imaging correlated with myelopathy.

Thirty-one patients (29 males and two females, 13-87 years of age (mean, 46.7 years] with acute spinal cord injury were studied by MR (magnetic resonance) imaging and the results were correlated with neurological findings. Magnetic resonance images were obtained with a 0.5 T superconductive MR scanner (Phillips Gyroscan S5). Initial imaging was performed within 24 hours after trauma in 13 patients, 1-7 days in 13 patients and 7-14 days in five patients. Twenty-six patients underwent follow-up examinations with MR imaging. Cord abnormalities including cord compression (23 patients), cord swelling (seven patients), and abnormal signal intensities on either T1 or T2-weighted images (26 patients) were observed on initial examination. Multivariate analysis showed that cord compression and abnormal intensities on T1-weighted images were important prognostic indicators. Hyperintensity on T2-weighted images was non-specific but correlated well with clinical recovery. Magnetic resonance imaging is useful in predicting the prognosis and for planning treatment following spinal cord injuries.

Acute Disease↗
PubMed1990

Effect of dietary alpha-linolenate/linoleate balance on crescent type-anti-glomerular basement membrane nephritis in rats.

Rats were fed diets with three different ratios of alpha-linolenate (18:3 n-3) and linoleate (18:2 n-6), and then crescentic-type anti-glomerular basement membrane (GBM) nephritis was induced. The urinary protein levels and the plasma urea nitrogen levels were significantly higher, and histological abnormalities of glomeruli were seen more frequently in the high-alpha-linolenate group than in the high-linoleate group. The differences in dietary alpha-linolenate/linoleate balances were reflected in the proportions of arachidonate and eicosapentaenoate in glomerular phospholipids. Our results indicate that dietary enrichment with alpha-linolenate causes unfavorable effects in this anti-GBM nephritis model.

Animals↗
PubMed1990

Spinal cord compression due to ossification of ligaments: MR imaging.

A total of 108 patients with ossification of the posterior longitudinal ligament (OPLL) (n = 92), ossification of the yellow ligament (OYL) (n = 8), or both (n = 8) were examined with magnetic resonance (MR) imaging performed with 0.5-T superconductive and 0.22-T resistive units. OPLL was demonstrated as a low-signal-intensity band between the bone marrow of the vertebral body and the dural sac on T1- and T2-weighted images. Continuous cervical OPLL was easier to diagnose than segmental cervical OPLL. T2-weighted images were more useful for detection of ossification of the ligaments. OYL was recognized as an impression on the posterior dural sac. Formation of bone marrow within an area of ossification, shown as increased or intermediate signal intensity, was observed in 56% of the cases of continuous OPLL, 11% of the cases of segmental OPLL, and none of the cases of OYL. The degree of cord compression was more severe in continuous OPLL. Degeneration of the disk was frequently associated with both types of OPLL.

Adult↗
PubMed1990

Studies on the nephrotoxicity of aminoglycoside antibiotics and protection from these effects (8): Protective effect of pyridoxal-5'-phosphate against tobramycin nephrotoxicity.

We investigated the effect of pyridoxal-5'-phosphate (PALP) on tobramycin (TOB)-induced nephrotoxicity in rats. Paper electrophoretic analysis showed that in the mixture of TOB and PALP, the spot corresponding to TOB alone almost disappeared and the spot associated with TOB overlapped with that associated with PALP, although the spots of TOB alone and PALP alone were observed as single spots on the cathode and anode sides, respectively. The overlapping of both compounds indicated that TOB could directly interact with PALP in vitro. In the assay of TOB binding to renal brush border membranes (BBMs), PALP significantly inhibited the binding of TOB to BBMs by interacting with TOB outside of BBMs vesicles. Intrarenal TOB levels in rats receiving TOB and PALP were lower than those in rats given TOB alone. Combination with PALP markedly suppressed the urinary protein content, urinary N-acetyl-beta-D-glucosaminidase activity and blood urea nitrogen content elevated by TOB, and also reduced the degree of TOB-induced renal tubular cell necrosis. These results indicate that PALP protects the rat kidneys from TOB-induced nephrotoxicity and that the protective effect of PALP may be due to the reduced intrarenal TOB concentration and less binding to TOB to BBMs induced by the interaction of PALP with TOB.

Animals↗