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Biomedical subjects

K Fukuda

Publications and source records attributed to K Fukuda.

At least 577 records · Page 32Linked to original sources
PubMed1993

Keratan sulfate inhibits its release in rabbit chondrocyte.

Keratan sulfate (KS) is one of the major glycosaminoglycans in cartilage matrix proteoglycan. We find that exogenously added KS totally blocks keratanase sensitive glycosaminoglycan release measured by radiolabeled ligand. We also find that KS release is potentially inhibited by its own presence as measured by ELISA. When KS is digested with keratanase before its addition to the medium, its inhibitory effect on KS secretion is partially blocked. Exogenously added KS promotes the accumulation of the KS epitope in the cell layer. These data suggest that KS negatively regulates its own secretion.

Animals↗
PubMed1993

Cross-linked cytokeratin polypeptides in liver and hepatoma cells: possible association with the process of cell degeneration and death.

We investigated transglutaminase-induced cross-linking of cytokeratin polypeptides in liver and hepatoma cells. To overcome the difficulties in the biochemical analysis of highly cross-linked polymers and aggregates of cytokeratins, cross-linked cytokeratin dimers were analyzed by immunoblotting to evaluate the degree of cross-linking of cytokeratins. Covalently cross-linked cytokeratin dimers were not detectable in normal rat liver cells. However, cytokeratin dimers and high-molecular-weight cytokeratin polymers were detected in liver tissue with histological evidence of coagulative necrosis induced by ischemia or carbon tetrachloride. Treatment of cultured hepatoma cells with the Ca2+ ionophore A23187 showed a dose-dependent, time-dependent decrease of cell viability. The appearance of cytokeratin dimers was shown to be correlated with cell death. These results suggest that the transglutaminase-induced cross-linking of cytokeratin polypeptides in liver and hepatoma cells is closely associated with the process of cell degeneration and death.

Animals↗
PubMed1993

[Evaluation of pulmonary venous flow patterns in left heart failure: a study using transesophageal Doppler echocardiography].

Pulmonary venous flow (PVF) patterns in left heart failure were evaluated using transesophageal pulsed Doppler echocardiography in 30 patients with dilated hearts (DH) and 30 normal subjects. Eighteen patients had myocardial infarction and 12 patients had dilated cardiomyopathy. The diagnostic criteria by using M-mode echocardiography were left ventricular end-diastolic dimensions (LVDd) of 5.5 cm or more and % LV fractional shortening (%FS) of less than 30%. Peak velocities of the first systolic (PVS1) and second systolic (PVS2) forward waves of PVF, %FS and total amplitude of mitral annular motion in the patient group were significantly decreased compared with the normal group. However, there were no differences in these parameters between the 22 patients (DH-1 group) with a mean pulmonary capillary wedge pressure (PCWP) of less than 18 mmHg and 8 patients (DH-2 group) with a PCWP of 18 mmHg or greater. Peak velocities of the diastolic forward wave of PVF and the early diastolic wave (D) of the LV inflow velocity in the DH-1 group were significantly decreased, and the peak velocity of the atrial contraction wave (A) of the LV inflow velocity was increased compared with those of the normal group. D of the LV inflow velocity, peak velocity of the diastolic forward wave, and peak velocity of the atrial systolic backward wave of the PVF in the DH-2 group were significantly increased compared with those of the DH-1 group. Significant positive correlations were observed between peak velocity of the diastolic forward wave and D or PCWP in the patient group, but the latter relationship was not linear. The A/D ratio of the LV inflow velocity was significantly decreased, and the ratio of the amplitudes of atrial contraction wave to total vertical deflection on the apexcardiogram of the DH-2 group were significantly increased compared with those of the DH-1 group. A patient with extensive myocardial infarction associated with development of severe LV dysfunction (PCWP = 23 mmHg) and a "pseudonormalization" pattern of LV inflow velocity demonstrated markedly increased peak velocities of the diastolic and atrial systolic forward wave, and decreased PVS2. However, the peak velocities of the diastolic and atrial systolic forward wave were decreased, and that of PVS2 was increased with fair improvement of LV dysfunction (PCWP = 10 mmHg) and with compensatory augmentation of the atrial contraction wave A of LV inflow velocity.(ABSTRACT TRUNCATED AT 400 WORDS)

Cardiomyopathy, Dilated↗
PubMed1993

Local immune response in persistent cervical dysplasia.

OBJECTIVE: To investigate the differences in local immune response between persistent and regressive cervical dysplasia. METHODS: We conducted a quantitative study of Langerhans cells, pan-T cells, and helper-inducer T cells in the subepithelial connective tissue using immunohistochemical techniques with S-100 protein antibody, UCHL1, and OPD4, respectively, in 52 paraffin sections. The subjects were patients with persistent cervical dysplasia and a comparable control group of 46 patients with regressive dysplasia. RESULTS: In the subepithelial stroma, the mean (+/- standard deviation) numbers of S-100- and OPD4-positive cells in the persistent group were 8.6 +/- 8.1 and 84.6 +/- 66.3, respectively, compared with 15.1 +/- 9.4 and 147.0 +/- 67.7, respectively, in the regression group. These data demonstrate a significant reduction of Langerhans cells and helper-inducer T cells (P < .0002 and P < .0001, respectively) with persistent dysplasia. CONCLUSION: The decreased numbers of S-100-positive Langerhans cells and helper-inducer T cells in persistent dysplasia compared to those of regressive dysplasia strongly support a decreased local immune response in persistent cervical dysplasia.

Adult↗
PubMed1993

[Evaluation of clinical usefulness of 99mTc-GSA, a functional hepatic imaging agent--correlation with per-rectal portal scintigraphy].

Liver scintigraphy using 99mTc-GSA, which binds specifically to the asialoglycoprotein receptors on the surface of the hepatocytes, was performed in 41 patients with chronic liver disease (11 chronic hepatitis cases and 30 liver cirrhosis) to investigate the correlations between the images and the various liver function tests. Two liver functional indexes, HH15 for plasma clearance of 99mTc-GSA and LHL15 for liver accumulation of 99mTc-GSA, showed significant differences between the chronic hepatitis group and the decompensated liver cirrhosis group. These indexes also showed significant correlations with the liver function tests such as serum albumin level and prothrombin time. HH15 and LHL15 correlated with the per-rectal portal shunt index obtained in 10 patients by 99mTcO4- per-rectal portal scintigraphy. These results suggest that HH15 and LHL15 have value as new liver functional indexes.

Adult↗
PubMed1993

Demonstration of extensive chromatin cleavage in transplanted Morris hepatoma 7777 tissue: apoptosis or necrosis?

Cell death may occur by either of two mechanisms: necrosis or apoptosis (programmed cell death). In this paper, we demonstrate extensive chromatin cleavage into oligonucleosome-length fragments (DNA ladder) in transplanted Morris hepatoma 7777 tissue, which is suggestive of the stimulation of an endogenous endonuclease activity previously found to be involved in the process of apoptosis. The existence of many apoptotic cells, which are morphologically characterized by condensed cytoplasm and basophilic nuclear fragments, were also seen in this tissue. In vivo and in vitro experiments were designed to further differentiate the morphological and biochemical features of necrosis and apoptosis in liver and hepatoma cells. Liver tissue undergoing ischemic necrosis showed a distinct DNA ladder pattern without demonstrating the morphology of apoptosis, indicating that chromatin cleavage into oligonucleosomal-length fragments is not confined to apoptotic cell death, at least in liver cells. In in vitro-cultured McA-RH7777 cells, however, DNA ladder pattern was detected only in cells showing characteristic morphology of apoptosis. From these two criteria (i.e., characteristic morphology and DNA ladder), it was strongly suggested that the apoptotic process is highly activated in the transplanted 7777 tissue. Based on the results obtained from in vitro experiments, it was suggested that tumor apoptosis may represent a residual attempt at autoregulation within the expanding tumor population and/or may result from mild cellular injuries such as hypoxia, nutrient deficiency, or other unknown noxious factor(s). We also showed evidence that apoptosis is inducible in hepatoma cells in vitro by a wide range of mild injuries or stimuli.

Animals↗
PubMed1993

Establishment of two distinct human hepatocellular carcinoma cell lines from a single nodule showing clonal dedifferentiation of cancer cells.

Hepatocellular carcinomas often contain tumor cells of more than one histological grade. The clonal relationship and biological behavior of hepatocellular carcinoma cells in histologically heterogeneous areas have not been fully explored. We established two distinct human hepatocellular carcinoma cell lines (HAK-1A and 1B) from a single nodule showing a three-layered structure with a different histological grade in each layer. Morphologically, HAK-1A and 1B resembled well-differentiated hepatocellular carcinoma cells in the outer layer of the original tumor and poorly differentiated ones in the inner layer, respectively. HAK-1B appeared less differentiated morphologically and more aggressive biologically than HAK-1A; HAK-1B had a shorter doubling time, higher tumorigenicity and an aneuploid DNA index. Chromosome analysis revealed many different abnormalities in the two cell lines, in which, however, two identical structural abnormalities (2q+ and 17p+) were identified. Moreover, sequence analysis of the p53 gene showed identical mutations at codon 242 in both cell lines. These findings suggest that the two cell lines are of clonal origin and that hepatocellular carcinomas consisting of cancerous tissues of more than one histological grade may reflect clonal dedifferentiation in the tumor. Furthermore, we predict that a clonal, morphologically less differentiated subpopulation such as HAK-1B is more aggressive in proliferation and may be closely related to subsequent tumor progression in hepatocellular carcinoma.

Base Sequence↗
PubMed1993

[Molecular biology in development of fatty liver--regulation of apolipoprotein B synthesis].

Apolipoprotein B (apo B) synthesis in fatty liver was described in this review. Apo B synthesis has not been intensively studied in fatty liver. Recently, we demonstrated that hepatic apo B mRNA level increased in two experimental models of fatty liver. Davidson et al. reported that apo B mRNA editing was enhanced in fatty liver induced by refeeding after fasting. However, further investigation is needed to clarify whether alteration in apo B gene regulation participates in development of fatty liver.

Animals↗
PubMed1992

Photoreaction of bacteriorhodopsin at high pH: origins of the slow decay component of M.

The absorption spectrum of light-adapted purple membrane in 3 M KCl is dependent on temperature even in the room temperature region. Temperature-induced difference spectra at various pH values suggested that the trans isomer of bacteriorhodopsin, bR570, is in thermal and/or photodynamic equilibrium with several different conformers. The major second conformer occurring at neutral pH had the same spectroscopic properties as the 13-cis isomer, and its content at 35 degrees C was estimated to be more than 20%. Heterogeneity in the protein conformation became more significant above pH8, where temperature-induced difference spectra exhibited a negative peak at 580 nm and a positive peak at 296 nm. This absorption change is very similar to that observed upon the formation of the N intermediate, suggesting that an N-like conformer occurs at high pH and temperature. A significant temperature dependence was also seen in the M decay kinetics at high pH, which were described by two decay components; i.e., the fast decaying M (Mf) was predominant at low temperature, but the amplitude of the slow component (M(s)) increased with increasing temperature. It is suggested that M(s) is generated upon excitation of the N-like conformer, in which the residue (Asp-96) usually acting as a proton donor to the Schiff base is deprotonated. The N-like conformer could be N itself, because M(s) was enhanced when N was accumulated by background light. A strong correlation between the amplitude of M(s) and the concentration of N was also revealed by the accumulation kinetics of Mf, M(s), and N after the onset of continuous actinic light.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacteriorhodopsins↗
PubMed1992

Tissue selectivity of pravastatin sodium, lovastatin and simvastatin. The relationship between inhibition of de novo sterol synthesis and active drug concentrations in the liver, spleen and testis in rat.

Tissue selectivity of pravastatin sodium (pravastatin), lovastatin and simvastatin, 3-hydroxy-3-methylglutaryl-CoA reductase inhibitors was examined by measuring inhibition of de novo sterol synthesis and active drug concentrations in the liver, spleen and testis in rats after a single oral administration (25 mg/kg) of these drugs. Regarding tissue drug concentrations, all three drugs were liver selective: concentrations of drugs in the liver were about ten-times higher than those in the spleen and testis. On the other hand, pravastatin was far more liver selective in inhibiting sterol synthesis than two other inhibitors: pravastatin inhibited de novo sterol synthesis in the liver but minimally in the spleen and testis, whereas lovastatin and simvastatin inhibited in all three tissues. Microautoradiographic and in vitro cellular-uptake studies demonstrated that pravastatin remained in the extracellular space in the spleen, whereas the other drugs entered the cell. We conclude that pravastatin exhibits a liver-selective inhibition of sterol synthesis because the agent permeates the cell membrane in the liver, but not in non-hepatic tissues.

Animals↗
PubMed1992

Double helix formation of phosphatidylcholine myelin figures.

Double helix formation of phosphatidylcholine myelin figures has been studied by use of optical microscopy. The winding of the double helices was looser than a geometrically possible one and the pitch was related proportionally to the outer radii of helical myelin figures. The regularity in the winding was explained in terms of the intermembrane binding energy and the bending elastic energy.

Molecular Conformation↗
PubMed1992

Activation of collagen IV gene expression in F9 teratocarcinoma cells by 3-deazaadenosine analogs. Indirect inhibitors of methylation.

3-Deazaadenosine analogs can function as inhibitors and also as alternative substrates of S-adenosylhomocysteine (AdoHcy) hydrolase. In cells treated with the analogs, AdoHcy invariably accumulates, leading to inhibition of cellular methylation. F9 teratocarcinoma cells, stably transfected with two collagen (IV) promoter-enhancer-CAT constructs and treated with 10 microM 3-deazaadenosine, 3-deaza-(+-)-aristeromycin or 3-deazaneplanocin, showed a strong induction of CAT activities without affecting differentiation. In comparison, the same 3-deaza analogs did not affect the CAT activity in F9 cells transfected with the beta-actin promoter-CAT construct. Furthermore, Northern blot analysis of endogenous mRNA from wild-type F9 cells treated with the 3-deaza nucleosides all showed an induction of the collagen alpha 1(IV) chain mRNA. Thus, the 3-deaza analogs most likely affect DNA methylation because their results are consistent with the previous observation that the integrated collagen alpha 1(IV) promoter-enhancer constructs were activated with 5-azacytidine.

Adenosylhomocysteinase↗