PubMed Health⌕ Search

Biomedical subjects

T Funahashi

Publications and source records attributed to T Funahashi.

At least 19 recordsLinked to original sources
PubMed1992

A point mutation of low-density-lipoprotein receptor causing rapid degradation of the receptor.

The exons of the low-density-lipoprotein-(LDL)-receptor gene from a Japanese patient with homozygous familial hypercholesterolemia were amplified by the polymerase chain reaction (PCR), and their nucleotide sequences were determined. A point mutation from G to C was found in exon 9, which was expected to change Asp at position 412 to His. This amino acid change occurred within the epidermal-growth-factor-precursor homology domain of the LDL receptor, slightly impairing the processing from the precursor to the mature form and causing rapid degradation of the mature form in the fibroblasts of the patient. The mutant LDL-receptor gene transfected into COS-1 cells expressed a LDL-receptor protein with the same properties as the protein expressed in the fibroblasts of the patient; impaired processing and rapid degradation of the synthesized receptor protein. The mutation was identified in family members of the patient by dot-blot hybridization of PCR-amplified DNA with the mutant oligonucleotide. The family members carrying the mutant gene showed higher serum cholesterol levels than the others. However, their cholesterol levels were also greatly influenced by the apolipoprotein-E phenotype.

Base Sequence↗
PubMed1992

Stimulation of the activity and mRNA level of hepatic triacylglycerol lipase by triiodothyronine in HepG2 cells.

We have studied the effects of triiodothyronine (T3) on the production of hepatic triacylglycerol lipase (HTGL) in the human hepatocellular carcinoma cell line, HepG2, by measuring its activity and mRNA levels. The HTGL activity released into the medium by heparin, increased after the addition of T3 in a both time- (27% increase after 24 and 75% increase after 48 h) and dose-dependent manner (maximum activity with over 0.2 micrograms/ml of T3 in the medium). Messenger RNA levels of HTGL in cells incubated with T3 for 24 and 48 h were increased by 33% and 98% compared to those of the control. These results suggest that the production of HTGL may be regulated by thyroid hormone at the level of gene expression.

Blotting, Northern↗
PubMed1992

Marked enhancement of acyl-CoA synthetase activity and mRNA, paralleled to lipoprotein lipase mRNA, in adipose tissues of Zucker obese rats (fa/fa).

To clarify the role of acyl-CoA synthetase in development of obesity, the mRNA levels and activities were studied in Zucker fatty rats (fa/fa). In Zucker fatty rats compared with their lean littermates, marked enhancement of ACS were observed in adipose tissues. Obese/lean rats ratio of ACS activity and mRNA in abdominal subcutaneous fat (3.3- and 3.9-fold, respectively) were greater than in mesenteric fat (2.0- and 2.2-fold). The enhancement of ACS activity and mRNA in the liver of fatty rats (1.2- and 1.8-fold) were less than those in the adipose tissues. There were no enhancement of ACS activities and mRNA levels in heart tissue of the obese rats. LPL mRNA levels were also enhanced in adipose tissue of fatty rats and obese/lean ratio of LPL mRNA was also higher in abdominal subcutaneous fat than mesenteric fat (6.2- vs 3.1-fold). The larger obese/lean rats ratio of LPL and ACS parameters in abdominal subcutaneous fat than mesenteric fat may be related to the observation that the increase of subcutaneous fat weight was larger than that of mesenteric fat weight in fatty rats (21.1- vs 4.9-fold). Integrated enhancement of LPL and ACS gene expression in adipose tissue may play an important role in the development of obesity.

Adipose Tissue↗
PubMed1992

Genetic structure, isolation and characterization of a Bacillus licheniformis cell wall hydrolase.

A DNA fragment containing the gene for a cell wall hydrolase of Bacillus licheniformis was cloned into Escherichia coli. Sequencing of the fragment showed the presence of an open reading frame which encodes a polypeptide of 253 amino acids with a molecular mass of 27,513. The gene was designated as cwlM, for cell wall lysis. The deduced amino acid sequence indicated that there is a repeated sequence consisting of 33 amino acid residues in the C-terminal region. Deletion of the C-terminal region did not lead to any loss of cell wall lytic activity. The gene product purified from E. coli cells harboring a cwlM-bearing plasmid exhibited a M(r) value of 29 kDa on SDS-polyacrylamide gels, and characterization of the specific substrate bond cleaved by CWLM indicated that the enzyme is an N-acetylmuramoyl-L-alanine amidase (EC 3.5.1.28). The enzyme hydrolyzed the cell wall of Micrococcus luteus more efficiently than those of B. licheniformis and B. subtilis, but the truncated CWLM (lacking the C-terminal region) had lost this preference. CWLM prepared from B. subtilis cells harboring a plasmid containing cwlM had a similar M(r) value to that from E. coli. Amino acid sequence homologies between CWLM and other amidases, and their protein structures are discussed.

Amino Acid Sequence↗
PubMed1992

Low-density lipoproteins in hyperalphalipoproteinemic heavy alcohol drinkers have reduced affinity for the low-density lipoprotein receptor.

Heavy alcohol intake causes a marked inhibition of cholesteryl ester transfer protein (CETP) activity resulting in cholesterol ester enrichment of HDL. In this study we have characterized LDL of 35 chronic heavy alcohol drinkers with hyperalphalipoproteinemia to clarify the effect of alcohol on the metabolism of LDL. Serum concentrations of LDL-cholesterol and apolipoprotein B were normal, while the chemical composition of LDL was characterized by depletion of cholesteryl ester and enrichment of triglyceride. The LDL particles of the drinkers were significantly smaller in size than those of controls and had reduced affinity for LDL receptors of normal human fibroblasts. After cessation of alcohol, these abnormal characteristics returned toward normal along with elevation of CETP activity. These results suggest that heavy alcohol intake alters the compositions and particle size of LDL, consequently reducing their affinity for LDL receptors. This may be attributed, at least in part, to the reduction of CETP activity.

Adult↗
PubMed1992

Non-macrophage-related accumulation of cholesterol during probucol treatment in familial hypercholesterolemia: report of two cases.

Two patients receiving long-term (3-4 years) treatment with probucol for familial hypercholesterolemia (FH) developed diffuse yellow lesions over the upper eyelids suggesting lipid storage in those tissues (diffuse lipid-storage lesions). Interestingly, each patient had shown a substantial reduction in their cholesterol levels together with a marked regression of their tendon xanthomas or typical xanthelasmas during treatment. To evaluate the role of probucol in this unusual finding we conducted histological and immunochemical evaluations of the lesions (removed surgically) and compared them with those of a non-probucol-treated subject with FH and typical audinal xanthelasma. In both probucol-treated patients the lesions were filled with foam cells and contained large amounts of cholesteryl ester. However, immunochemical analysis of the lesions of one patient using anti-monocyte monoclonal antibody (HAM56) demonstrated that they were not composed of macrophage-derived foam cells in contrast to those of the non-probucol-treated subject which stained clearly with anti-monocyte monoclonal antibody. In each case the foam cells did not react with muscle-actin-specific monoclonal antibody (HHF35). It appears that non-macrophage-related diffuse lipid-storage lesions may occur even during treatment with probucol despite the reduction in cholesterol levels and the regression of xanthomas, suggesting that probucol may alter the distribution of cholesterol from the macrophage to other cells.

Adult↗
PubMed1992

Polydisperse low-density lipoproteins in hyperalphalipoproteinemic chronic alcohol drinkers in association with marked reduction of cholesteryl ester transfer protein activity.

Long-term heavy alcohol intake is well known to increase serum high-density lipoprotein (HDL) cholesterol concentrations. Epidemiologic studies have shown that the protective effect of alcohol intake against coronary heart disease (CHD) is observed in moderate alcohol drinkers, but not in heavy ones. To clarify whether heavy alcohol intake may cause abnormalities in lipoprotein metabolism, we analyzed the plasma lipoproteins in eight male chronic heavy alcohol drinkers with marked hyperalphalipoproteinemia. Although their serum HDL cholesterol levels were remarkably high, ranging from 2.67 to 3.58 mmol/L, three patients had CHD and corneal arcus was present in seven patients. Cholesteryl ester transfer protein (CETP) activity was reduced in all subjects (7.3% +/- 4.2%/10 microL/18 h in alcohol drinkers v 20.5% +/- 2.4%/10 microL/18 h in control; mean +/- SD, P < .001). The CETP mass levels were also markedly reduced in these subjects. The analysis of low-density lipoprotein (LDL) on nondenaturing polyacrylamide gradient gel electrophoresis revealed that four subjects with severely low CETP activity (< 25% of control) had polydisperse LDLs, similar to those observed in genetic CETP deficiency. The other four subjects with approximately half the normal CETP activity had homogeneous but smaller-sized LDLs, as compared with control subjects. Particle size of HDL was larger than that of normal control HDL in all subjects. After cessation of alcohol intake, plasma HDL cholesterol levels were decreased and LDLs became more homogeneous and normal in size, in parallel with elevation of CETP activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Left atrial myxoma metastasizing to the aorta, with intraluminal growth causing renovascular hypertension.

The first case of 'a metastatic intraluminal myxoma of the aorta' is reported. The patient was a 48-year-old man who had already developed metastases to his skin and brain from a left atrial myxoma. Then, his myxoma grew in his leg and intraluminally in the aorta and caused renovascular hypertension. Surgical removal of the tumor could relieve his hypertension, but he finally died 6 months after surgery. The findings at autopsy were described and previous reports on metastasizing left atrial myxomas were also reviewed.

Aorta, Abdominal↗
PubMed1990

Hypocholesterolaemic factor from gallbladder cancer cells.

A patient is reported with drug-resistant familial hypercholesterolaemia in whom serum cholesterol fell after the onset of gallbladder cancer with intraperitoneal invasion. Cancer cells were obtained from ascitic fluid and a cultured cell line established. Incubation of the culture medium of these cells with skin fibroblasts from the patient and from normal subjects increased low-density lipoprotein (LDL) receptor activity in a dose-dependent manner. These results show that gallbladder cancer cells from this patient secrete a substance that stimulates LDL receptor activity. This substance may have contributed towards reduction of serum cholesterol.

Adenocarcinoma↗
PubMed1990

Adsorption of anti-dsDNA antibodies by immobilized polyanionic compounds.

Antibodies to dsDNA are characteristically present in serum from patients with systemic lupus erythematosus (SLE), and have been shown to have the capacity to react with various molecules bearing repeating negative charges. After a number of polymeric or monomeric molecules with differently charged groups and hydrophobic molecules had been coupled covalently as ligands on cellulose gel, the adsorption capacities of the ligands for anti-dsDNA antibodies were evaluated. It was found that gels coupled with polyanionic dextran sulphate (DXS) and polyacrylic acid (PA) and monoanionic sulphanilic acid (SA) absorbed anti-dsDNA antibodies effectively. DXS gel also adsorbed antibodies to ssDNA and heparan sulphate, antigens with repeating negatively charged moieties, while no ligand was able to adsorb anti-nRNP antibodies. The finding that DXS gels adsorbed anti-dsDNA antibody in proportion to their charge density, and that the interaction between anti-dsDNA and DXS gel is broken readily by an increase in ionic strength, indicated that the binding is ionic in nature. Moreover, virtually all F(ab')2 anti-dsDNA became adsorbed onto the DXS gels, suggesting that the binding occurred via specific antigen-binding sites on the antibody molecule. Binding of these polyanion-binding autoantibodies with anionic sites in the glomerular basement membrane may therefore cause the tissue damage observed in SLE.

Adsorption↗
PubMed1989

Analysis of a recycling-impaired mutant of low density lipoprotein receptor in familial hypercholesterolemia.

A mutant low density lipoprotein (LDL) receptor with abnormal ligand binding and recycling abilities was found in a patient with familial hypercholesterolemia. The molecular weights of the precursor and the mature form of the receptor were 72,000 and 115,000, respectively, which were about 45,000 smaller than those of the normal receptor. The mutant receptor was concluded to be present on the cell surface because the mature form was susceptible to Pronase digestion, and specific monoclonal antibody against the LDL receptor (IgG-C7) could bind to the cell surface. This mutant receptor could not bind LDL, but could bind other ligands for the LDL receptor, beta-migrating very low density lipoprotein, and the apolipoprotein E-lipid complex. After the receptor bound to the ligand, it disappeared from the cell surface of the mutant cells faster than that of normal cells, showing that, in the mutant cells, the receptor was not efficiently recycled back to the cell surface. Southern blotting of the genomic DNA from the patient showed a large deletion of about 12 kilobases around the epidermal growth factor precursor homology domain. For further characterization of the mutant, we cloned a 9.4-kilobase EcoRI/XbaI fragment, which was expected to contain the deletion joint. Mapping and sequencing analyses of the receptor gene showed that exons 7-14 were deleted. The nucleotide sequence suggested that this mutation may have occurred by recombination between repetitive Alu sequences in introns 6 and 14 of the receptor gene. The recombination brought about a complete deletion of the gene coding the epidermal growth factor precursor homology domain. The characteristics of the receptor protein produced by this mutation were similar to those of an artificial mutation constructed by Davis et al. (Davis, C. G., Goldstein, J. L., Südhof, T. C., Anderson, R. G. W., Russell, D. W., and Brown, M. S. (1987) Nature 326, 760-765) in which the whole gene coding this domain was deleted. The clinical phenotype of the patient having this mutation was similar to that of so-called "receptor-defective" type familial hypercholesterolemia, in which cells show detectable, but markedly reduced activity of the LDL receptor.

Base Sequence↗
PubMed1989

Association of apolipoprotein E with the low density lipoprotein receptor: demonstration of its co-operativity on lipid microemulsion particles.

When human apolipoprotein E (apoE), which forms a self-associated tetramer in an aqueous solution, bound to the surface of triolein/phosphatidylcholine microemulsion with a particle diameter of 26 nm, it became monomeric on the lipid particle surface without strong evidence for its accumulation on a particular particle that might be expected from its tetramer formation in the aqueous phase. ApoE in the form of the self-associated tetramer did not inhibit binding of human low density lipoprotein (LDL) to its receptor on cultured human skin fibroblast. LDL binding was inhibited only when apoE was bound to the lipid particle surface. The affinity of the apoE-containing lipid particle to the LDL receptor was of the same order as that of LDL on the basis of particle molarity when the surface of the particle was covered with apoE up to 40 to 50% of the saturation level. When the particle was covered more with apoE, the affinity increased by some 20 times. Since the surface of the lipid particle was saturated with 7 apoE molecules, the particle seemed to require to have at least 4 apoE molecules on its surface in order to obtain high binding affinity to LDL receptor.

Adsorption↗
PubMed1989

Selective removal of anti-double-stranded DNA antibodies by immunoadsorption with dextran sulphate in a patient with systemic lupus erythematosus.

A dextran sulphate gel column removed anti-double-stranded DNA antibodies (anti-dsDNA) selectively, efficiently, and safely from the circulation of a patient with systemic lupus erythematosus (SLE). The mechanism of the removal is thought to be due to cross reactivity of anti-dsDNA with dextran sulphate, which has negatively charged units. Selective removal of anti-dsDNA is expected to contribute not only to the treatment but also to elucidation of the pathogenesis of SLE.

Adult↗
PubMed1988

Selective reduction of cholesterol in HDL2 fraction by probucol in familial hypercholesterolemia and hyperHDL2 cholesterolemia with abnormal cholesteryl ester transfer.

Long-term treatment with probucol induced marked regression of xanthoma in patients with both homozygous and heterozygous familial hypercholesterolemia despite a substantial accompanying decrease in high-density lipoprotein (HDL) cholesterol. Furthermore, a close correlation was found between the extent of the regression and the reduction of HDL cholesterol, which suggests that the probucol-induced decrease in HDL may not be an atherogenic change, but may reflect a favorable change for lipoprotein metabolism. The present study also evaluated the effects of probucol on HDL metabolism in patients with familial hyperHDL2 cholesterolemia who had extremely high levels of HDL cholesterol ranging from 130 to 280 mg/dl. Premature corneal opacities were present in 2 patients, 1 of whom also had coronary artery disease despite high HDL cholesterol levels. In the 2 cases, the net transfer of cholesteryl ester from HDL to very low density lipoprotein and LDL was impaired, and low hepatic triglyceride lipase activity was observed, but cholesteryl ester transfer protein was not deficient. Administration of probucol to these patients caused a marked reduction of serum cholesterol, which was accounted for exclusively by a reduction in the HDL2 fraction. The size of the HDL2 particles, which had been much larger, decreased to normal, and the net transfer rate of cholesteryl ester was normalized. In the other 3 cases of hyperHDL2 cholesterolemia, the cholesteryl ester transfer activity was completely deficient. Unlike its effect in the first 2 cases, probucol did not cause any change in lipid and apoprotein in the 3 patients with complete deficiency of cholesteryl ester transfer activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Carrier Proteins↗
PubMed1988

Mutations of the low density lipoprotein receptor in Japanese kindreds with familial hypercholesterolemia.

Mutations of the low density lipoprotein (LDL) receptor in 16 Japanese kindreds with homozygous familial hypercholesterolemia (FH) were studied using an anti-LDL receptor antibody. The LDL receptor mutations in Japanese FH were heterogeneous and included defects in synthesis, post-translational processing, ligand-binding activity, and internalization of the LDL receptor. Of the 16 kindreds, 10 were receptor-negative and 5, receptor-defective types and 1 was an internalization-defective type with respect to LDL binding. The receptor-negative group was further subdivided into four groups: those with cells producing (i) no immunodetectable receptor (five kindreds); (ii) 160-kd mature receptors, which were quite scarce (two kindreds); (iii) receptors that could not be processed to the mature receptor properly (two kindreds); and (iv) receptors with an apparent molecular weight smaller than normal (one kindred). The last kindred synthesized an about 155-kd mature receptor that was rapidly degraded. This finding is compatible with the low concentration of the cell surface LDL receptors and decreased binding activity for LDL in the cells of this kindred. The receptor-defective group, which could produce a residual amount of functional receptors, exhibited a lower tendency to coronary artery disease than the receptor-negative group.

Homozygote↗
PubMed1988

A novel system of LDL apheresis combining a centrifugal plasma separator with a specific LDL adsorption column.

A novel system of low density lipoprotein (LDL) apheresis for familial hypercholesterolemia (FH) was developed, combining a centrifugal plasma separator (IBM-2997) with a new adsorption column specific to lipoproteins containing apolipoprotein B (apo-B), and its operation was compared to previous methods. The present system selectively removed LDL without the substantial reduction of high density lipoprotein that was seen with other methods using membrane filters. The capacity for LDL removal was slightly more reduced with the adsorption column than with the membrane filters when a single column was used. Since the ability to obtain plasma in the centrifugal system was much higher than in the system using membrane filters for plasma separation, efficient apheresis could be performed in a much shorter time, without making an arterio-venous shunt. Remixing of blood cells, such as platelets, with the separated plasma sometimes raises the pressure within the plasma component separator, but the problem could be avoided by withdrawing the buffy coat fraction, using the WBC pump of the IBM separator. In conclusion, the novel system, combining the centrifugal plasma separator with the adsorption column, has proved, in our hands, to be a more useful and more convenient method than those previously used for the treatment of severe FH.

Adsorption↗