Search PubMed⌕ Search

Biomedical subjects

K Kawamura

Publications and source records attributed to K Kawamura.

At least 343 records · Page 19Linked to original sources
PubMed1993

Effects of endothelial denudation in flow-induced arterial dilatation.

The effects of endothelial denudation of the flow-induced arterial dilatation in the rabbit common carotid artery (carotid) were studied. After endothelial denudation with a 3-French balloon catheter, the left carotid was made arterio-venous (A-V) fistula to the left external jugular vein in four adult male rabbits (3-4 kg). Five rabbits which were given A-V fistula without denudation were used as controls. Blood flow rates, luminal dimensions, hemodynamic parameters and morphology were studied after 1 week. In spite of a significant increase of blood flow, the lumen diameter of the left carotid with denudation was significantly smaller than that without denudation. The assumed wall shear stress in the left carotid with denudation was significantly higher than in that without denudation. In the denuded segment, the internal elastic lamina and media were preserved with no or slight intimal thickening, composed of mononuclear cell proliferation; however, there were frequent disruptions of the internal elastic lamina in the non-denuded left carotid. We consider that flow-induced arterial dilatation occurs when the endothelial lining is preserved.

Animals↗
PubMed1993

[The inhibitory effects of Takusha on the formation, growth and aggregation of calcium oxalate crystals in vitro].

The inhibitory effects of Takusha on the formation, growth and aggregation of calcium oxalate crystals were estimated by the microplate method and the use of Coulter counter TAII in the diluted urine system and undiluted urine system. In the diluted urine system, the inhibitory effect on aggregation and growth was calculated from the changes in the number and volume of crystals by the seed crystal method. Takusha had a strong inhibitory effect on the aggregation and growth when the concentration was above 10 micrograms/ml. In measuring the metastable limit by the microplate method, Takusha had a mild inhibitory effect on the formation of crystals above the concentration of 1 mg/ml. In the undiluted urine system, after determining the metastable limit, the formation and growth of calcium oxalate crystals which precipitated in response to a load of sodium oxalate were measured. Takusha had a strong inhibitory effect on the formation and growth at the concentration of 0.1-1 mg/ml. Takusha had no glycosaminoglicans in the dimethylmethylene blue assay and had an inhibitory effect on aggregation and growth when its molecular weight was over 10,000. Therefore, Takusha might be useful for preventing stones in recurrent stone formers.

Calcium Oxalate↗
PubMed1992

Noninvasive detection of left ventricular diastolic dysfunction using M-mode echocardiography to assess left ventricular posterior wall kinetics in hypertrophic cardiomyopathy.

In patients with hypertrophic cardiomyopathy (HC), it is difficult to determine the severity of left ventricular (LV) diastolic dysfunction. Three different patterns of LV posterior wall motion were found by M-mode echocardiography in patients with HC, and the use of these patterns is proposed as a new noninvasive index of the severity of LV diastolic dysfunction. M-mode echocardiograms were recorded prospectively from 35 patients with HC, and the posterior wall motion pattern in late systole and early diastole was classified into the following 3 types: (1) normal motion (n = 9); (2) flat motion--flat motion from late systole to early diastole, followed by rapid backward movement (n = 13); and (3) downward motion--slow backward movement from late systole (n = 13). There were no differences in the severity or type of hypertrophy, LV systolic function and pulsed Doppler indexes of LV filling among these 3 groups. However, LV end-diastolic pressure was increased in the groups with flat (15 +/- 6 mm Hg) and downward (16 +/- 9 mm Hg) motion. Furthermore, the maximal rate of decrease in LV pressure (normal 1,450 +/- 300, flat 1,250 +/- 300 and downward 860 +/- 80 mm Hg/s) and the time constant of LV pressure reduction (normal 60 +/- 15, flat 70 +/- 25 and downward 101 +/- 34 ms) showed a stepwise deterioration from the normal to the flat and then to the downward motion groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II↗
PubMed1992

The chloroplast-targeting domain of plastocyanin transit peptide can form a helical structure but does not have a high affinity for lipid bilayers.

Conformational properties and interactions with lipid membranes were studied for the chemically synthesized peptides PC(1-37) and PC(1-43), corresponding to the N-terminal 37 and 43 residues, respectively, of the transit peptide of the precursor to plastocyanin of Silene pratensis. PC(1-43) covers the entire chloroplast targeting domain of the transit peptide. CD spectra of PC(1-37) and PC(1-43) showed that both peptides have little ordered structure in aqueous solutions but form partially helical conformations in the presence of detergent micelles or in methanol. Vesicle disruption and direct-binding experiments revealed, however, that neither PC(1-37) nor PC(1-43) had a high affinity for lipid membranes. Since in the intact plastocyanin transit peptide the chloroplast-targeting domain is followed by a hydrophobic thylakoid-transfer domain, the plastocyanin precursor may well be transported to the chloroplast surface first with the aid of the thylakoid-transfer domain. The chloroplast-targeting domain may then form a helical structure in the lipid environments, and a chloroplast-specific motif displayed on the helical structure may be recognized by a receptor protein located at the chloroplast envelope membranes.

Amino Acid Sequence↗
PubMed1992

Oxidative damage on DNA induced by asbestos and man-made fibers in vitro.

We compared the potential of asbestos and man-made fibers to attack DNA by the determination of the yield of 8-hydroxy-2'-deoxyguanosine (8-OH-dGuo) under several in vitro conditions. Asbestos induced 6.6-99.8 of 8-OH-dGuo per 10(5) dGuo in calf thymus DNA after 20 h of incubation, while the levels of 8-OH-dGuo in man-made fibers were low (3.6-9.4). The amounts of 8-OH-dGuo were strongly stimulated by the addition of H2O2 in asbestos, but not in man-made fibers. However, the yield of 8-OH-dGuo was induced more than that with asbestos by the further addition of FeSO4 in attapulgite, fiberglass, potassium titanate whisker, and metaphosphate polymer. The addition of ethylene diamine tetra-acetic acid (EDTA) promoted the induction of 8-OH-dGuo with asbestos and H2O2. The effects of mannitol (known as a hydroxy radical scavenger) were not dramatic on 8-OH-dGuo induction by all fibers except fiberglass and basic magnesium sulfate whisker, which induced higher amounts after mannitol addition than in these fibers and H2O2. Therefore, it was suggested that asbestos could damage DNA, resulting in 8-OH-dGuo as a cause of point mutation, and also several types of man-made fibers had similar effects to asbestos under certain conditions.

Animals↗
PubMed1992

Point mutations in mitochondrial DNA in patients with hypertrophic cardiomyopathy.

Recent advances suggest that mutations in nuclear DNA are involved in the etiology of autosomal dominant hypertrophic cardiomyopathy. Mitochondria have their own DNA, and mutations in mitochondrial DNA have been shown to contribute to the genesis of various diseases. In this study, we developed rapid sequencing methods with the use of a fluorescence-based sequencing system and analyzed total mitochondrial DNA of seven patients with nonautosomal dominant hypertrophic cardiomyopathy. Multiple point mutations were observed in all patients with hypertrophic cardiomyopathy, although some of them were common among the subjects examined and the others are unique to each subject. Point mutations in transfer RNA genes were observed in five of the seven patients, and point mutations that replaced conserved amino acids were also observed. These mutations may result in the impairment of mitochondrial function. According to these results, mutations in mitochondrial DNA may contribute to the genesis of some cases of nonautosomal dominant hypertrophic cardiomyopathy, and our methods may be useful for the detection of point mutations in mitochondrial DNA.

Adult↗
PubMed1992

Ultrastructural alterations of the conduction system in mice exhibiting sinus arrest or heart block during Coxsackievirus B3 acute myocarditis.

By light and electron microscopy we studied the sinus nodes and atrioventricular (AV) conducting tissue of six C3H/He mice having coxsackievirus B3 acute myocarditis. Sinus arrest was documented in all six mice, and second- or third-degree AV block was documented in three of the six mice. Although myocarditic changes in the conduction system, especially in the sinus node, were less than those in atrial and ventricular working myocardium, there were distinct abnormalities within both the sinus node and AV conducting tissue in all six hearts. Important ultrastructural alterations were inflammatory cell infiltrates and significant injury of specialized cells and of neural tissue. Specialized cells showed various features of degeneration and necrosis. Neural tissue damage included degeneration of axons and Schwann cells and disorganization of the neuromuscular junctions. Inflammatory cells, particularly macrophages, were often in intimate contact with injured specialized cells and neural tissue. Interstitial edema and bleeding and lymphatic vessel dilatation were also observed. These pathologic changes are considered to play an important role in the development of the documented disturbances of rhythm and conduction.

Animals↗
PubMed1992

Tumor incidence was not related to the thickness of visceral pleural in female Syrian hamsters intratracheally administered amphibole asbestos or manmade fibers.

Histological observations were performed on female Syrian hamsters 2 years after the intratracheal administration of amphibole asbestos, amosite, and crocidolite to evaluate the tumorigenicity of six types of fine manmade fibers (reported previously). A mesothelioma and a lung tumor were induced in 20 animals administered amosite, but no tumors were found in the crocidolite group. Because this incidence is not higher than that of manmade fibers, such as basic magnesium sulfate fiber [9 tumor-bearing hamsters in 20 hamsters (9/20)], metaphosphate fiber (5/20), calcium sulfate fiber (3/20), and fiberglass (2/20), it is suggested that some types of manmade fibers have a greater ability than asbestos to induce tumors. Moreover, as a specific observation in manmade fiber groups, tumors were induced at intracelial organs rather than at the pleural cavity. On the other hand, the average thickness of visceral pleura was higher in all asbestos and manmade fiber groups than in the control (2.9 microns), for instance, 36.95 microns in potassium titanate fiber group, 15.90 microns crocidolite group, 13.00 microns basic magnesium sulfate fiber group, and 10.45 microns in the rockwool group. Although both pleural thickening and mesothelioma are known as peculiar lesions in asbestos-exposed people, it might also be suggested that these lesions could be induced by different mechanisms from the result that there was no relation between the pleural thickening and mesothelioma incidence in hamsters.

Adenoma↗
PubMed1992

Umbilical endometriosis.

A 41-year-old woman with umbilical endometriosis is presented. The umbilical lesion is repeatedly painful and there is a bloody discharge simultaneous with the menstrual period. Treatment of umbilical endometriosis is by excision. Hormonal therapy results in its incomplete regression. Umbilical endometriosis is a very rare disease, but should be considered in the differential diagnosis of umbilical tumors.

Adult↗
PubMed1992

Effects of lisinopril upon cardiac hypertrophy, central and peripheral hemodynamics and neurohumoral factors in spontaneously hypertensive rats.

OBJECTIVE: Left ventricular function (LVF) after reversal of left ventricular hypertrophy (LVH) with antihypertensive therapy is still controversial. The present study was undertaken in spontaneously hypertensive rats (SHR) to determine whether LVF of the regressed heart with lisinopril is normally maintained. DESIGN: We compared cardiac function of SHR after reversal of LVH induced by lisinopril with that observed in control SHR and also with effects after a 4-week washout period. METHODS: Administration of lisinopril began at 15 weeks of age and continued for 20 weeks. Cardiac index, renal blood flow, leg muscle blood flow, plasma renin activity, atrial natriuretic peptide level, and norepinephrine concentration were determined. RESULTS: Lisinopril decreased body weight, blood pressure and left ventricular weight and increased leg muscle blood flow; cardiac index and renal blood flow were unaltered. Although norepinephrine concentration was unchanged, plasma renin activity increased and atrial natriuretic peptide decreased in treated SHR. Peak left ventricular pumping ability during volume loading was comparable in the two groups. After a 4-week washout period, left ventricular mass and blood pressure increased but remained lower than controls; cardiac index at rest and during volume loading was similar in the two groups. CONCLUSIONS: These data indicate that LVF of the regressed heart induced by lisinopril was well preserved at rest, during volume loading and also after spontaneous recurrence of hypertension in SHR.

Animals↗
PubMed1992

Kappa light chain nodular glomerulosclerosis with conspicuous crescent formation and tubulointerstitial injury. Report of a case.

We describe a 39-year-old man who developed kappa light chain nodular glomerulosclerosis with superimposed conspicuous crescent formation and extensive tubulointerstitial injury. The clinical picture was characterized by nephrotic syndrome and rapidly progressive glomerulonephritis. Incessantly progressive loss of renal function culminated in irreversible renal failure 7 weeks after initial manifestations of renal insufficiency. The patient has since been maintained on thrice weekly hemodialysis with chemotherapy for five years. At the time of pathologic diagnosis by renal biopsy, there was no evidence of multiple myeloma, and no serum M-component or Bence-Jones proteinuria was detected. An initial bone marrow aspirate revealed the presence of 0.6% atypical lymphocytes as the sole abnormality, although these were later identified as atypical plasma cells. These cells had also infiltrated the renal interstitium. Crescentic kappa light chain nodular glomerulosclerosis lacking evidence of plasma cell dyscrasia should be included in the differential diagnosis of rapidly progressive glomerulonephritis.

Adult↗
PubMed1992

Difference in dilatation between endothelium-preserved and -desquamated segments in the flow-loaded rat common carotid artery.

To study arterial dilatation in response to increased flow, we observed the bilateral common carotid arteries (CCAs) of 10 16-week-old rats that were maintained for 8 weeks after construction of an arteriovenous (AV) fistula between the left CCA and the jugular vein at a level 20 mm distal from the aortic orifice. The flow in the left CCA increased 11-fold and that of the right CCA increased twofold compared with values before surgery. The left CCA showed complete desquamation of endothelial cells in the distal one third of the segment proximal to the AV fistula. In the left CCA the endothelium-preserved area dilated significantly (the luminal radius was 1.34 times larger than control; p less than 0.001, n = 4) with a significant increase of the cross-sectional area of the media (p less than 0.01, n = 4) and showed high wall shear stress (70 +/- 11 dynes/cm2 near the aortic orifice). In contrast, the endothelial cell-desquamated area did not dilate but did show very high wall shear stress (231 +/- 23 dynes/cm2) without any intimal smooth muscle cell proliferation. The right CCA dilated significantly (luminal radius was 1.07 times larger than control; p less than 0.001, n = 4) with a wall shear stress of 30 dynes/cm2 near the brachiocephalic orifice. All CCAs retained their fundamental arterial structure. We conclude that in the rat CCA, arterial dilatation in response to increased flow is a gradual remodeling process related to the presence of endothelial cells that have been influenced by the level of flow increase.

Animals↗
PubMed1992

Catabolism of hemoglobin-haptoglobin complex in microsome subfractions.

After internalization of hemoglobin-haptoglobin complex (Hb-Hp) via receptor-mediated endocytosis (RME) into liver parenchymal cells, organelles containing the complex distribute in the microsome fraction (Ms). Prior to the catabolism, Hb-Hp dissociates symmetrically into two 82,000-dalton (82 kDa) subunits. In the present investigation, the first event of Hb-Hp metabolism in Ms were further examined after [3H-heme, 14C-glogin]Hb-Ho or [125I-Hb]Hp injection to rats. Shortly after the internalization of Hb-Hp, this complex in Ms was intact. At 60 min after injection, radioactive materials of Ms extracted by freezing and thawing (F&T) with yield of 15% were composed of Hb-Hp, 82 kilodaltons (kDa) subunits and Hb metabolites with a ratio of 1:6:13. The heme metabolites were identified as [3H]bilirubin by high performance liquid chromatography (HPLC). The ratio of Hb-Hp/82 kDa subunits/Hb metabolites in microsome residue of the F&T was 40:8:1. The radioactivity in Ms at 60 min localized microsomes subfraction except Golgi light fraction. In electron microscope radioautography of microsome subfraction using [125I]Hb-Hp, silver grains were observed over or within morphologically heterogenous vesicles, e.g. vesicles containing very low density lipoprotein (VLDL) particles with appendage like multi-vesicular body (MVB) or compartment of uncoupling of receptor and ligand (CURL) in Goligi light and intermediate fractions. These studies suggest that Hb-Hp internalized by RME is dissociated symmetrically into two 82 kDa subunits in organelles of Ms, and that organelles with MVB or CURL-like structures are associated with Hb-Hp metabolism.

Animals↗
PubMed1992

Genetic analysis of dilated cardiomyopathy--HLA and immunoglobulin genes may confer susceptibility.

To identify genetic factors in the immune system which control the susceptibility to dilated cardiomyopathy (DCM), HLA class II DNA typing was performed in 61 Japanese patients, using PCR/SSO probe analyses. The frequencies of HLA-DQB1*0503 (15% vs 5%; RR = 3.06, chi 2 = 7.19) and DQB1*0604 (21% vs 10%; RR = 2.41, chi 2 = 6.20) were significantly increased and that of HLA-DQB1*0502 (RR = 1.74) was slightly increased in the DCM patients. The frequency of DQB1*0303 (16% vs 31%; RR = 0.44, chi 2 = 5.16) was significantly decreased in the patients. The increased HLA-DQB1 alleles have a histidine residue in common at the 30th codon for the HLA-DQ beta chain. Among the genetic markers studied by Southern blot analyses, IGLV (immunoglobulin lambda light chain, pV3.3) showed a strong association with DCM, i.e. A2/A2 genotype was found in 37.7% of patients whereas it was observed in only 18.9% of the control subjects (RR = 2.6, chi 2 = 7.77). The frequency of this genotype was higher in patients under age 45 years at the time of diagnosis (45.5%, RR = 3.6, chi 2 = 10.02). These results suggest that HLA and immunoglobulin genes are closely linked to susceptibility to DCM.

Adolescent↗
PubMed1992

Genomic detection of enteroviruses in the myocardium--studies on animal hearts with coxsackievirus B3 myocarditis and endomyocardial biopsies from patients with myocarditis and dilated cardiomyopathy.

We examined myocardial tissues for the presence of enteroviral RNA in animal models with experimental coxsackievirus B3 myocarditis and in endomyocardial biopsy samples obtained from patients clinically diagnosed as having dilated cardiomyopathy or myocarditis using polymerase chain reaction (PCR) gene amplification with enterovirus-generic primers and/or coxsackievirus B3-specific primers. In animal models, coxsackievirus B3 was detected in myocardial tissues up to 28 days, 56 days and 180 days after inoculation, in C3H/He mice, A/J mice and Syrian golden hamsters, respectively. The viral genomes were identified by in situ hybridization in myocardial cells and some interstitial cells in and around the myocarditic lesions in animals. In human endomyocardial biopsy samples, enteroviral RNA sequences were detected in 8 (32%) out of 25 patients with clinical dilated cardiomyopathy and in 3 (33%) out of 9 patients with clinical myocarditis. The patients showing histologic findings of myocarditis and clinical features resembling dilated cardiomyopathy had a high incidence (83%) of positive PCR result for enteroviral RNA sequences. Additionally, 25% of patients with dilated cardiomyopathy showing no histologic findings of myocarditis had positive PCR result. This study supports a link between viral myocarditis and dilated cardiomyopathy.

Adult↗
PubMed1992

Viral genomic detection in the hearts of C3H/He mice with experimental Coxsackievirus B3 myocarditis by gene amplification using the polymerase chain reaction.

On the basis of the detection of the enteroviral RNA in the hearts of patients with healed myocarditis and dilated cardiomyopathy, we investigated cardiac viral persistence in experimental myocarditis. Weanling C3H/He mice were given myocarditis by inoculation with coxsackievirus B3 (Nancy strain), and their hearts were examined by genomic studies and viral isolation up to the 180th day after inoculation. The virus was isolated from the heart until the 9th day. By slot-blot hybridization, viral RNA was also only detected until the 9th day in the heart. Specific DNA amplification using the polymerase chain reaction (PCR) was performed after a reverse transcriptase reaction, then followed by Southern blot hybridization with a 32P-labelled oligomer probe. This technique achieved the type-specific detection of coxsackievirus B3 even at a level of less than one of the 50% tissue culture infective dose (TCID50). With this technique, viral RNA was detected up to the 28th day after inoculation. Thus, the viral RNA persisted in the hearts of these mice even when infectious virus could no longer be detected.

Animals↗