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Biomedical subjects

T Funahashi

Publications and source records attributed to T Funahashi.

At least 73 records · Page 4Linked to original sources
PubMed1997

Increased serum remnant lipoproteins in patients with apolipoprotein E7 (apo E Suita).

Apolipoprotein (apo) E7 was originally identified by Yamamura et al. in subjects with atherosclerotic cardiovascular diseases (J. Clin. Invest. 1984;74:1229). However, the lipoprotein abnormalities associated with apo E7 phenotype have not been elucidated. In the current study, to clarify the physiological roles of apo E7, lipoprotein abnormalities were studied in 12 apo E7 heterozygotes. A total of seven subjects were hyperlipidemic and five subjects were normolipidemic. The apo E phenotype was apo E7/3 in 11 subjects and apo E7/4 in one subject. Polymerase chain reaction revealed that all of the subjects with apo E7 phenotype had the same mutation as that of apo E(Suita) as reported previously (J. Biochem. 1989;105:249). All the hyperlipidemic subjects were over 40 years of age and two of them also had and severe coronary heart disease. Ultracentrifugal analysis revealed that the cholesterol level both in very low density lipoprotein and in intermediate density lipoprotein (IDL) was substantially higher in hyperlipidemic apo E7 heterozygotes, compared with control subjects and that the IDL cholesterol was also increased even in normolipidemic apo E7 heterozygotes. Polyacrylamide gel electrophoresis of lipoproteins showed a midband, which implies the increase of remnant lipoproteins, in 11 subjects out of 12, irrespective of the presence or absence of hyperlipoproteinemia. In two cases, a broad beta pattern was observed similar to that seen in type III hyperlipoproteinemia. Dietary therapy was dramatically effective for the treatment of hyperlipidemia in patients with apo E7. These findings confirm that apo E is crucial for remnant lipoprotein metabolism and that apo E7 is related to the increase in serum remnant lipoproteins, which leads to hyperlipoproteinemia in association with obesity, aging and impaired glucose metabolism.

Adult↗
PubMed1997

Importance of intra-abdominal visceral fat accumulation to coronary atherosclerosis in heterozygous familial hypercholesterolaemia.

OBJECTIVES: Hyper-low-density lipoprotein (LDL)-cholesterolaemia is a potent risk factor for coronary atherosclerosis. We have recently demonstrated that a cluster of risk factors including insulin resistance, glucose intolerance, hypertriglyceridaemia, and hypertension based on intra-abdominal visceral fat accumulation are closely related to coronary artery disease. In the current study, we evaluated the relationship between visceral fat accumulation and the severity and distribution of coronary atherosclerosis in familial hypercholesterolaemia (FH). DESIGN: The effect of visceral fat accumulation on coronary lesions and risk factors in patients with FH was investigated. SUBJECTS: Thirty-one male patients with heterozygous FH who underwent coronary angiography. MEASUREMENTS: Abdominal fat distribution was estimated by a cross-sectional computed tomographic scan at the umbilical level. Plasma lipid, glucose and insulin concentrations and blood pressure were measured. A 75 g oral glucose tolerance test was also performed. RESULTS: The patients were divided into two groups according to the degree of visceral fat accumulation. Fifteen patients had high visceral fat accumulation (High VF group) and 16 patients had normal visceral fat accumulation (Normal VF group). Body mass index (BMI) and subcutaneous fat area were significantly higher in the high VF group. Baseline serum triglyceride was significantly higher and baseline low-density lipoprotein (LDL)-cholesterol and reduction of LDL-cholesterol during treatment were significantly lower in High VF group. Fasting plasma glucose and insulin concentrations, and systolic and diastolic pressures were significantly higher in the High VF group. Significant correlations were found between visceral fat area and the sum of the glucose and insulin concentration during an oral glucose tolerance test. Visceral fat area was significantly correlated with the severity of coronary stenosis index. Distal coronary lesions were significantly more frequent in the High VF group. Moreover, the correlation between the visceral fat area and coronary stenosis index was found to be independent of age, BMI, and subcutaneous fat area by multiple regression analysis. CONCLUSIONS: Visceral fat accumulation is a potent cardiovascular risk factor in heterozygous FH.

Abdomen↗
PubMed1997

Two decades of annual medical examinations in Japanese obese children: do obese children grow into obese adults?

OBJECTIVE: To investigate trends in frequency of obese children in Japan over two decades, the frequency of obese children who grow into obese adults and predictive factors for adult obesity. DESIGN: Annual cross-sectional studies for 22 y (1974-1995) with a follow-up study. SUBJECTS: Cross-sectional: Cumulatively 13,186 obese (% of standard body weight (SBW): > or = 120%) schoolchildren including 3158 extremely obese (> or = 140% of SBW) children out of 203,088 schoolchildren (age: 6-14 y) in Izumiohtsu City, Osaka, Japan. FOLLOW-UP: 151 initially obese children (initial age: 6-14 y and age at follow-up: 20-35 y) who lived in Izumiohtsu City. CONTROL: 3552 Japanese men and 4631 Japanese women (age: 20-35 y). MEASUREMENTS: Cross-sectional: height, weight, trunk circumference, skin-fold thickness, blood pressure and blood biochemicals. FOLLOW-UP: height, weight, trunk circumference, skin-fold thickness during childhood, and body height and weight at follow-up. Adulthood obesity: > or = 120% of the average body mass indices (BMI) of the controls. RESULTS: Frequency of obese children increased from 5% to more than 10%, and that of extremely obese children increased from 1% to more than 2% during these 22 y. These increases were most prominent in the schoolboys aged 9-11 y. Prevalence of hyperglycemia and hyperlipidemia in the extremely obese children did not change, and that of hypertension and abnormal liver function gradually decreased during these two decades. After coming of age, 32.2% of the initially obese boys (relative risk: 5.3) and 41.0% of the initially obese girls (relative risk: 6.7) remained obese. BMI, percentage of the SBW and skin-fold thickness at the biceps during childhood were significantly larger in currently-obese girls. Positive correlations were demonstrated between these variables and percentage SBW at follow-up. CONCLUSIONS: Childhood obesity is increasing in Japan, especially in boys aged 9-11 y. Approximately 32% of the obese boys and 41% of the obese girls grow into obese adults, and the degree of obesity is a predictive factor for adult obesity.

Adolescent↗
PubMed1997

Cloning and sequencing of the Vibrio parahaemolyticus fur gene.

A ferric uptake regulatory gene (fur) was cloned from Vibrio parahaemolyticus WP1 by a polymerase chain reaction-based technique followed by functional complementation of a fur mutation in Escherichia coli. A sequence analysis showed that, at the amino acid level, the V. parahaemolyticus Fur protein is 81% identical with the Fur protein from E. coli and over 90% identical with those of the Vibrio species.

Amino Acid Sequence↗
PubMed1997

Characterization of the human apobec-1 gene: expression in gastrointestinal tissues determined by alternative splicing with production of a novel truncated peptide.

In humans, both the expression of apobec-1 and the C to U deamination of apoB mRNA are confined to the small intestine. In order to understand the tissue-restricted pattern of apobec-1 expression, we have isolated the chromosomal gene spanning the human apobec-1 locus. The human apobec-1 gene spans 18 kb and contains five exons, all of which are translated. Transcription initiation, determined by RNase protection and primer extension analyses, is localized to a single start site 34 nt upstream of the open-reading frame in exon 1. A common, but functionally silent, gene polymorphism was detected than changes Ilc80 to MCl. RNase protection and reverse-transcription PCR analysis demonstrated the presence of an exon 2-skipped form of apobec-1 mRNA that arises through use of an alternative splice acceptor. This alternative splicing causes a frame-shift that produces a novel, 36 amino acid peptide. The exon 2-skipped form accounts for approximately 50% of apobec-1 mRNA in the adult small intestine and up to 90% of apobec-1 mRNA in the developing gut. An antipeptide antibody identified the truncated protein in villus cells of the adult small intestine. These data suggest that exon 2-skipping may represent an important control mechanism regulating apobec-1 gene expression in humans.

APOBEC-1 Deaminase↗
PubMed1997

Cloning and characterization of the rat apobec-1 gene: a comparative analysis of gene structure and promoter usage in rat and mouse.

ApolipoproteinB (apoB) mRNA editing involves a C to U deamination of the nuclear apoB mRNA and occurs in mammalian small intestine and in the liver of certain species. This reaction is mediated by a multicomponent enzyme complex that includes a catalytic subunit, apobec-1. Apobec-1 mRNA is widely expressed in the rat and mouse and is subject to tissue-specific regulation. In order to understand the basis for the species- and tissue-specific pattern of apobec-1 gene expression we have cloned and characterized the rat chromosomal apobec-1 gene. We demonstrate its structural organization and regulation in comparison to that of the mouse apobec-1 gene. The rat apobec-1 gene spans 16 kb and includes one untranslated (exon A) and five translated exons (exons 1-5). The mouse apobec-1 gene contains eight exons, of which the first three (exons A, B, C) are untranslated. Independent approaches demonstrated three distinct clusters of transcription initiation sites in both species, including exon A, the distal region of exon 1, and a separate group in the proximal region of exon 1. These transcription start sites generate three distinct mRNA species whose proportions differ in a tissue-specific fashion. Promoter-luciferase reporter constructions using regions flanking exon A and exon 1 of the rat apobec-1 gene identified two functional regions upstream of exon 1 that independently promote luciferase expression in transfected hepatoma and colon cancer cells. These data serve as a basis for an understanding of the regulation of apobec-1 gene expression, in particular the mechanisms that serve to restrict its expression to the gastrointestinal tract in higher mammals.

APOBEC-1 Deaminase↗
PubMed1996

Hepatic expression of the catalytic subunit of the apolipoprotein B mRNA editing enzyme (apobec-1) ameliorates hypercholesterolemia in LDL receptor-deficient rabbits.

Apolipoprotein (apo) B48, a protein contained in intestinally derived lipoprotein particles, is synthesized by post-transcriptional editing of apoB100 mRNA. This reaction is mediated by an enzyme complex that includes the catalytic subunit, apobec-1. The liver of most mammals, by contrast, contains only unedited apoB mRNA and secretes apoB100, the major protein component of plasma low-density lipoprotein (LDL). Because rabbits, like humans, fail to edit hepatic apoB100 mRNA, we introduced a recombinant adenovirus encoding apobec-1 into the livers of LDL receptor-defective rabbits to determine the impact on lipoprotein metabolism of hepatic apoB48 secretion. Transgene expression was mainly confined to the liver and was sustained for up to 3 weeks following virus administration, as evidenced by the presence of apobec-1 mRNA and the ability of hepatic S100 extracts to edit a synthetic apoB RNA template in vitro. The transient induction of hepatic apoB mRNA editing accompanied alterations in very-low-density lipoprotein (VLDL) size, the presence of apoB48 in fractions spanning the VLDL and LDL range, and modest reductions in total plasma cholesterol levels.

APOBEC-1 Deaminase↗
PubMed1996

Enhanced expression of PAI-1 in visceral fat: possible contributor to vascular disease in obesity.

The presence of obesity increases the risk of thrombotic vascular diseases. The role of fat accumulation and its effect on plasminogen activator inhibitor-1 (PAI-1) levels was investigated in humans and animals. Plasma PAI-1 levels were closely correlated with visceral fat area but not with subcutaneous fat area in human subjects. PAI-1 mRNA was detected in both types of fat tissue in obese rats but increased only in visceral fat during the development of obesity. These data suggest that an enhanced expression of the PAI-1 gene in visceral fat may increase plasma levels and may have a role in the development of vascular disease in visceral obesity.

3T3 Cells↗
PubMed1996

A compound heterozygote for familial hypercholesterolaemia with a homozygous mother.

Homozygous familial hypercholesterolaemia (FH) is a rare disorder in which the patients develop severe hypercholesterolaemia and premature coronary atherosclerosis from childhood. Here we report a unique family with clustering of homozygous FH. The proband was a 25-year-old man, who showed marked hypercholesterolaemia, multiple xanthomas and severe coronary atherosclerosis. His mother also showed the typical characteristics of homozygous FH. Sequencing analysis of the low-density lipoprotein receptor gene revealed that he was a compound heterozygote, carrying two different point mutations. One was a novel mutation, FH Wakayama (Cys-->Ser at 317), derived from his mother, and the other was a recurrent mutation, FH Niigata (T-->C at 1845 + 2, 5' splice signal in intron 12), derived from his father. The proband we report seems to be a very rare case of an FH homozygote born from a homozygous mother.

Adult↗
PubMed1996

Plasma leptin levels and body fat distribution.

The relation between body fat distribution and plasma leptin levels in the human was investigated in 51 obese and 41 non-obese subjects. Plasma levels of leptin showed a positive correlation with body mass index and subcutaneous fat area at the umbilicus level. However, a significant correlation between its plasma levels and visceral fat area was found in neither non-obese nor obese subjects. These results suggest that plasma leptin levels might be attributed mainly to the extent of subcutaneous adiposity in human obesity.

Adipose Tissue↗
PubMed1996

Rapid enhancement of acyl-CoA synthetase, LPL, and GLUT-4 mRNAs in adipose tissue of VMH rats.

Obesity is frequently accompanied by metabolic and cardiovascular complications. The accumulation of intra-abdominal visceral fat has been shown to be more closely related to various complications of obesity than that of subcutaneous fat. To elucidate the metabolic characteristics of visceral fat during fat accumulation, we examined the changes of acyl-CoA synthetase (ACS) mRNA abundance and its activity, glucose transporter (GLUT)-4, lipoprotein lipase (LPL), and very-low-density lipoprotein (VLDL) receptor mRNA abundances in mesenteric and subcutaneous fat in early stages of ventromedial hypothalamus (VMH)-lesioned rats. ACS activity increased 4.9-fold in the mesenteric fat on the 1st day, remaining unchanged in the subcutaneous fat. ACS, GLUT-4, and LPL mRNA levels were all increased in both fat tissues of VMH rats. The relative increase of mRNAs in VMH day 1 was greater in the mesenteric fat, suggesting that mesenteric fat shows rapid response during fat accumulation. VLDL receptor mRNA levels showed no significant change in either fat tissue. We conclude that ACS, GLUT-4, and LPL may contribute to fat accumulation at the gene expression level from a very early stage during the development of obesity.

Adipose Tissue↗
PubMed1996

A novel nonsense mutation (G181X) in the human cholesteryl ester transfer protein gene in Japanese hyperalphalipoproteinemic subjects.

Cholesteryl ester transfer protein (CETP) plays an important role in regulating the concentration and composition of high density lipoprotein (HDL) and low density lipoprotein (LDL). Although several genetic abnormalities causing CETP deficiency have been identified in the Japanese subjects with a marked hyperalphalipoproteinemia (HALP), there are many CETP-deficient subjects for whom the genetic abnormalities have not been clarified. In the present study, we analyzed the molecular basis of an HALP subject without CETP activity and mass, and found a novel mutation in the CETP gene. This novel mutation (G181X) was a G-to-T substitution at codon 181 of exon 6 which replaced a codon for glycine (GGA) with a premature stop codon (TGA). The G181X mutation created a new cutting site by restriction enzyme MaeIII. To estimate the frequency of G181X, we investigated unrelated 294 HALP (HDL-cholesterol > or = 2.59 mmol/L = 100 mg/dl) subjects by restriction fragment length polymorphism (RFLP) analysis with Mae III. One (0.34%) HALP subject was homozygous and four (1.36%) were heterozygous for this mutation. The allelic frequency of a G-to-T substitution at codon 181 of exon 6 was 0.0102 in HALP subjects. From the lipid analysis of the proband and the homozygote, it was clarified that the G181X mutation had dominant effects on HDL and LDL metabolism, similar to a G-to-A substitution at the 5' splice donor site of the intron 14 (1451 + 1G-->A). In conclusion, the G181X mutation is one of causes of HALP in the Japanese HALP subjects, having dominant effects on lipid metabolism.

Carrier Proteins↗
PubMed1995

A single point mutation in the splice donor site of the low-density-lipoprotein-receptor gene produces intron read-through, exon-skipped and cryptic-site-utilized transcripts.

Familial hypercholesterolemia is a genetic disorder caused by mutations of the low-density-lipoprotein (LDL) receptor gene. We characterized the structures of LDL receptor mRNA transcripts in the fibroblasts of a homozygous patient carrying a single base substitution (T-->C) at the 5' splice donor site of intron 12 of the LDL receptor gene. We identified three aberrant transcripts as a consequence of intron-12 read-through, exon-12 skipping and utilization of a cryptic splice donor site. Only a point mutation at the 5' splice donor site caused the production of three alternatively spliced products. None of these transcripts produced a functional LDL receptor protein in this patient.

Alternative Splicing↗
PubMed1995

Enhanced expression of rat obese (ob) gene in adipose tissues of ventromedial hypothalamus (VMH)-lesioned rats.

A responsible gene of genetically obese (ob/ob) mouse has recently been isolated. Genetic disruption of ob gene causes massive obesity. To elucidate the pathophysiological regulation of ob gene, we examined the gene expression in fat tissues of a non-genetical obese model, VMH-lesioned rats. The ob mRNA was identified in both subcutaneous and mesenteric fat tissues in the control rats. In VMH-lesioned rats, the abundance of ob mRNA increased after the gain of body weight and marked expression was observed on 15th day after making VMH lesion. These data suggest that ob gene might be up-regulated with fat accumulation even in non-genetically obese animals.

Adipose Tissue↗
PubMed1995

Decreased affinity of low density lipoprotein (LDL) particles for LDL receptors in patients with cholesteryl ester transfer protein deficiency.

We have reported that the disorder of lipoprotein metabolism in hyperalphalipoproteinaemic patients with a deficiency of cholesteryl ester transfer protein (CETP) is characterized by the polydisperse low density lipoprotein (LDL) particles and the accumulation of cholesteryl ester (CE) in high density lipoprotein (HDL) particles, forming cholesterol-induced HDL (HDLc)-like particles. In the present study we have investigated the interaction of these abnormal LDL with LDL receptors of normal human fibroblasts. Since the ultracentrifugally separated LDL fraction (1.019 < d < 1.063 g mL-1) from the CETP-deficient patients contained HDLc-like particles, these particles were removed by anti-apolipoprotein (apo) A-I immunoaffinity column chromatography. The lipoproteins eluted in the unbound fraction of this column did not contain apo A-I, so this fraction was considered to be authentic LDL. The authentic LDL of the patients were deficient in CE and rich in triglycerides and apo B. The authentic LDL itself showed polydispersity, ranging in size from 23 nm to 30 nm. The affinity of these abnormal LDL particles for LDL receptors was analysed by a competitive assay in which cold LDL from the patients or control compete with 125I-labelled LDL for fibroblast LDL receptors. The concentration of LDL particles at which 50% of 125I-labelled normal LDL was replaced was two to three times higher for the patients than for the normal control. Therefore, the affinity of patient LDL was thought to be reduced compared to that of control LDL. These results demonstrate that CETP may play an important role in making LDL particles homogeneous and rich in CE.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Common mutations in the low-density-lipoprotein-receptor gene causing familial hypercholesterolemia in the Japanese population.

Familial hypercholesterolemia (FH) is a common genetic disorder caused by mutations of the LDL-receptor gene. In the present study, we investigated four Japanese FH homozygotes and identified five point mutations: a splice site mutation in intron 12 (the 1845 + 2 T-->C mutation), a missense mutation in exon 7 (the C317S mutation), a nonsense mutation in exon 17 (the K790X mutation), a missense mutation in exon 14 (the P664L mutation), and a missense mutation in exon 4 (the E119K mutation). We developed simple methods for detecting these mutations. When we examined the presence of these mutations in 24 unrelated FH homozygotes, the 1845 + 2 T-->C mutation was found in 7 of them, and the other four mutations were unique for each proband. We also screened 120 unrelated FH heterozygotes for these mutations and found that the frequencies of the 1845 + 2 T-->C, C317S, K790X, P664L, and E119K mutations were 13.3% (16/120), 6.7% (8/120), 6.7% (8/120), 3.3% (4/120), and 1.7% (2/120), respectively. These mutations were found in more than 30% of unrelated Japanese FH patients. By using the detection methods developed in this study, the diagnosis of more than 30% of the genetic bases of Japanese FH heterozygotes is expected.

Adult↗