Biomedical subjects

H Seo

Publications and source records attributed to H Seo.

At least 37 records · Page 2Linked to original sources

PubMed2000

Pyrrolidine dithiocarbamate inhibits TNF-alpha-dependent activation of NF-kappaB by increasing intracellular copper level in human aortic smooth muscle cells.

Pyrrolidine dithiocarbamate (PDTC) is a metal-chelating compound that acts as antioxidant or pro-oxidant and is widely used to study redox regulation of cell function. In the present study, we investigated effects of PDTC and another antioxidant, N-acetyl-l-cysteine (NAC), on TNF-alpha-dependent activation of NF-kappaB in human aortic smooth muscle cells (HASMC). Treatment of the cells with TNF-alpha induced the activation of p65/p50 heterodimer NF-kappaB and increased the mRNA levels of monocyte chemoattractant protein (MCP)-1. Pretreatment with PDTC markedly suppressed the NF-kappaB activation and expression of MCP-1 by inhibiting IkappaB-alpha degradation. In contrast, NAC had no effect. PDTC concomitantly increased the intracellular levels of copper, and bathocuproinedisulfonic acid, a non-cell-permeable chelator of Cu(1+), inhibited the PDTC-induced increase in intracellular copper level and reversed the PDTC effects on IkappaB-alpha, NF-kappaB, and MCP-1. These results indicate that TNF-alpha-dependent expression of MCP-1 in HASMC is tightly regulated by NF-kappaB and that intracellular copper level is crucial for the TNF-alpha-dependent activation of NF-kappaB in HASMC.

Acetylcysteine↗

PubMed2000

Spatiotemporal expression of BDNF in the hippocampus induced by the continuous intracerebroventricular infusion of beta-amyloid in rats.

The beta-amyloid protein (Abeta) is the major component of senile plaques found in the brain in Alzheimer's disease (AD). Its neurotoxic properties in vivo, however, are not well defined. Since the expression of neurotrophin genes is considered an important component of the intrinsic neuroprotective response to insults, we analyzed the gene expression of neurotrophins in the brains of rats which received a continuous infusion of Abeta-(1-42) into the cerebroventricle. Northern blot analysis revealed a significant increase in brain-derived neurotrophic factor (BDNF) expression in the hippocampus but no change in the cerebral cortices. The alteration peaked on days 3-7 and returned to the basal level on day 14 after the start of Abeta-(1-42) infusion. No significant changes in nerve growth factor or neurotrophin-3 mRNA expression were observed. The infusion of Abeta-(1-40) and (25-35) also triggered the expression of BDNF mRNA, whereas neither Abeta-(40-1) nor (1-16) had any effect. In situ hybridization histochemistry revealed that the expression mainly occurred in the hilus and granular layer of the dentate gyrus and to a lesser extent in the pyramidal neurons of the CA1 region. These results demonstrate that the continuous intracerebroventricular infusion of Abeta induces selective and spatiotemporal expression of BDNF mRNA in the hippocampus.

Alzheimer Disease↗

PubMed2000

Effect of angiotensin-converting enzyme inhibitor (enalapril or imidapril) on ventilation during exercise in patients with chronic heart failure secondary to idiopathic dilated cardiomyopathy.

Eighteen patients with heart failure were studied to clarify whether angiotensin-converting enzyme inhibitor treatment improves excess ventilation during exercise. Treatment with angiotensin-converting enzyme inhibitors had a beneficial effect on excess ventilation during exercise, without significant improvement in exercise capacity in patients with moderate congestive heart failure.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed2000

p97 ATPase, an ATPase involved in membrane fusion, interacts with DNA unwinding factor (DUF) that functions in DNA replication.

DNA unwinding factor (DUF) unwinds duplex DNA and is supposed to function in DNA replication in Xenopus egg extracts. Here we report the isolation and analysis of a DUF-interacting factor. By immunoprecipitation, we found that p97 ATPase (p97) interacts with DUF in Xenopus egg extracts. This interaction was confirmed by the in vitro binding of purified p97 with DUF. When sperm chromatin was added to Xenopus egg extracts to construct nuclei active in DNA replication, p97 was incorporated into the nuclei. These data suggest that the complex of DUF and p97 may function in DNA replication.

Adenosine Triphosphatases↗

PubMed2000

Identification of a novel myosin-Va mutation in an ataxic mutant rat, dilute-opisthotonus.

Mutations of the myosin-Va gene (Myo5a) cause diluted coat color in mice and are occasionally associated with severe neurological disorders. Dilute-opisthotonus (dop) is a spontaneous gene mutation in the rat, and phenotypes of the homozygote (dop/dop) are similar to those of the Myo5a-deficient mouse, suggesting that the mutation resides in the rat Myo5a gene. To elucidate the molecular basis of the dop mutation, we cloned the rat Myo5a cDNA from the wild type and the dop/dop. The wild-type rat Myo5a cDNA contained a 5487-bp ORF and showed higher homology with Myo5a of the other species than Myr6 (Myo5b) in the rat. A 141-bp in-frame deletion was detected in the head region in the dop cDNA. An intragenic rearrangement consisting of a 306-bp inversion associated with 17-bp and 217-bp deletions were identified in the Myo5a gene of the dop genome. This rearrangement involved a 141-bp exon, which was skipped in the dop transcript. The MyoVA protein expression was severely impaired in the dop/dop brain. This is the first report to define the dop mutation as the Myo5a gene abnormality in the rat.

Amino Acid Sequence↗

PubMed2000

An oral sorbent reduces overload of indoxyl sulphate and gene expression of TGF-beta1 in uraemic rat kidneys.

BACKGROUND: An oral adsorbent (AST-120) delays the progression of chronic renal failure (CRF). The aims of the present study are to determine the effects of AST-120 on the localization of indoxyl sulphate in uraemic rat kidneys, and to examine whether AST-120 reduces the renal cortical gene expression of transforming growth factor (TGF)-beta1, tissue inhibitor of metalloproteinase (TIMP)-1 and pro-alpha1(I)collagen, and ameliorates glomerular and tubulointerstitial injuries in uraemic rats. METHODS: Two weeks after 5/6-nephrectomy, 10 rats were divided into pairs such that both rats in each pair exhibited almost the same levels of serum creatinine, blood urea nitrogen and creatinine clearance. One rat from each pair was assigned to a control uraemic group, the other to a uraemic group which received AST-120 everyday for 11 weeks. The localization of indoxyl sulphate was studied by immunohistochemistry using a monoclonal anti-indoxyl sulphate antibody we had developed. The renal cortical gene expression was studied by using northern blotting. RESULTS: Rats treated with AST-120 showed decreased levels of serum creatinine, blood urea nitrogen and urinary protein as well as increased levels of creatinine clearance as compared with control uraemic rats. AST-120 markedly decreased indoxyl sulphate levels in both serum and urine. Immunohistochemistry demonstrated that indoxyl sulphate was localized in the renal proximal tubular epithelial cells, especially of dilated tubules, and that AST-120 markedly reduced the tubular staining of indoxyl sulphate. AST-120 attenuated interstitial fibrosis, tubular injury as well as glomerular sclerosis, and reduced the renal gene expression of TGF-beta1, TIMP-1 and pro-alpha1(I)collagen. CONCLUSIONS: AST-120 reduces the gene expression of TGF-beta1, TIMP-1 and pro-alpha1(I)collagen in the kidneys, and delays the progression of CRF, at least in part, by alleviating the overload of indoxyl sulphate on remnant proximal tubular epithelial cells.

Adsorption↗

PubMed2000

A potential role of activated NF-kappa B in the pathogenesis of euthyroid sick syndrome.

Euthyroid sick syndrome, characterized by low serum 3,5, 3'-triiodothyronine (T(3)) with normal L-thyroxine levels, is associated with a wide variety of disorders including sepsis, malignancy, and AIDS. The degree of low T(3) in circulation has been shown to correlate with the severity of the underlying disorders and with the prognosis. Elevated TNF-alpha levels, which accompany severe illness, are associated with decreased activity of type I 5'-deiodinase (5'-DI) in liver, leading us to speculate that high levels of this factor contribute to euthyroid sick syndrome. Here we demonstrate that the activation of NF-kappa B by TNF-alpha interferes with thyroid-hormone action as demonstrated by impairment of T(3)-dependent induction of 5'-DI gene expression in HepG2 cells. Inhibition of NF-kappa B action by a dominant-negative NF-kappa B reversed this effect and allowed T(3) induction of 5'-DI. Furthermore, we show that an inhibitor of NF-kappa B activation, clarithromycin (CAM), can inhibit TNF-alpha-induced activation of NF-kappa B and restore T(3)-dependent induction of 5'-DI mRNA and enzyme activity. These results suggest that NF-kappa B activation by TNF-alpha is involved in the pathogenesis of euthyroid sick syndrome and that CAM could help prevent a decrease in serum T(3) levels and thus ameliorate euthyroid sick syndrome.

Anti-Bacterial Agents↗

PubMed2000

Regulation of thyroid follicular cell function by intracellular redox-active copper.

Pyrrolidine dithiocarbamate (PDTC) is a metal-chelating compound that exerts prooxidant or antioxidant effects and is widely used to study redox regulation of cell function. In the present study, we investigated effects of PDTC on the function of rat thyroid follicular FRTL-5 cells. Treatment of the cells with PDTC resulted in a marked decrease in Pax-8 messenger RNA level and its DNA-binding activity. This decrease was associated with a significant reduction in thyroperoxidase (TPO) messenger RNA level. Expression of TTF-1 and thyroglobulin was not affected by PDTC. Treatment with PDTC also decreased DNA-binding activity of p53, a tumor suppressor protein, and increased cell proliferation rates. These changes were not observed by the treatment with another antioxidant, N-acetyl-L-cysteine, suggesting that the metal-chelating, prooxidant property of PDTC is responsible for its effects. Indeed, the intracellular level of copper was significantly increased by PDTC. Treatment with bathocuproinedisulfonic acid, a noncell-permeable chelator of Cu1+, abrogated the copper increase by PDTC and its effects on Pax-8 and TPO expression as well as on p53 binding. Taken together, these results indicate that the intracellular level of redox-active copper is crucial for Pax-8 and TPO expression and for proliferation of thyroid follicular cells.

Acetylcysteine↗

PubMed2000

Culture in vector-averaged gravity under clinostat rotation results in apoptosis of osteoblastic ROS 17/2.8 cells.

Space flight experiments and studies carried out in altered gravity environments have revealed that exposure to altered gravity conditions results in (mal)adaptation of cellular function. In the present study, we used a clinostat to generate a vector-averaged gravity environment. We then evaluated the responses of osteoblast-like ROS 17/2.8 cells subsequent to rotation at 50 revolutions per minute (rpm) for 6-24 h. We found that the cells started to detach from the substrate between 12 h and 24 h of rotation in clinostat but not in stationary cultures or after horizontal rotation (the latter serving as a motion control for turbulence, shear forces, and vibrations). At 24 h, 35% of clinorotated cells had detached and the cells underwent apoptotic death as evidenced by DNA fragmentation analysis, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) staining, and flow cytometry with Annexin V staining. The apoptotic death was associated with perinuclear distribution of cell-surface integrin beta1 and disorganization of actin cytoskeleton. These results suggest that vector-averaged gravity causes apoptosis of osteoblasts by altering the organization of the cytoskeleton. We hypothesize that apoptotic death of osteoblasts might play an important role in the pathogenesis of osteoporotic bone loss as observed in actual space flights.

Actins↗

PubMed2000

Effects of glucocorticoids on tumor necrosis factor alpha-dependent activation of nuclear factor kappaB and expression of the intercellular adhesion molecule 1 gene in osteoblast-like ROS17/2.8 cells.

Recently, we showed that tumor necrosis factor alpha (TNF-alpha) stimulates expression of the intercellular adhesion molecule 1 (ICAM-1) and interleukin-6 (IL-6) genes through activation of p65-p50 heterodimer nuclear factor KB (NF-kappaB) in rat osteoblast-like ROS17/2.8 cells. In the present study, we investigated effects of a synthetic glucocorticoid, dexamethasone (Dex), on TNF-alpha-dependent activation of NF-kappaB and expression of the ICAM-1 gene. ROS17/2.8 cells were pretreated with Dex for 6 h and then exposed to TNF-alpha. Electrophoretic mobility shift assay (EMSA) revealed that TNF-alpha-dependent activation of NF-kappaB was almost completely suppressed by Dex treatment. Increase in ICAM-1 messenger RNA (mRNA) level by TNF-alpha also was markedly suppressed by Dex. Western blot and immunocytochemical analyses showed that Dex attenuated the TNF-alpha-induced nuclear translocation of p65. Treatment with protein synthesis inhibitor cycloheximide (CHX) reversed the Dex effect, indicating that Dex requires de novo protein synthesis for its action. Northern blot analysis revealed that Dex increased IkappaB-alpha mRNA level synergistically with TNF-alpha, whereas it decreased p65 mRNA level. The p105 and IkappaB-beta mRNA levels were not altered by Dex. Consistent with the mRNA level, Dex increased the amount of IkappaB-alpha protein in the cytoplasm in either the presence or the absence of TNF-alpha. Considering a role of IkappaB to sequester NF-kappaB in the cytoplasm, it was suggested that an increase in IkappaB-alpha protein and the concomitant decrease in p65 synthesis account for the Dex-induced suppression of NF-kappaB activation in osteoblastic cells.

Animals↗

PubMed2000

Involvement of AP-1 and steroidogenic factor (SF)-1 in the cAMP-dependent induction of human adrenocorticotropic hormone receptor (ACTHR) promoter.

Adrenocorticotropic hormone receptor (ACTHR) is expressed predominantly in the adrenal glands, and its expression is upregulated by its own ligand, ACTH, via a cAMP-dependent pathway. In the present study, we characterized the 5'-regulatory region of human ACTHR gene to elucidate the molecular mechanisms underlying its adrenal-specific and ACTH/cAMP-dependent expression. The promoter region (-1017/+47 when the transcription start site is regarded as + 1) and its serial 5'-deletions (-764/+47, -503/+-47, -214/+47 and -56/+47) were ligated into the upstream of a luciferase (luc) reporter gene. These constructs were transfected into adrenocortical Y1 cells or non-adrenal JEG3 and Cos-1 cells. In all the cell lines, the luc activity gradually increased with serial 5'-deletions and the maximum activity was conferred by - 56/+ 47. However, the magnitude of luc activity of each deletion construct in non-adrenal cells was much less than that in Y1 cells, suggesting that the promoter functions in an adrenal-specific manner. We identified two Steroidogenic Factor (SF)-1-binding sites at -209 and -35. Electrophoretic mobility shift assay (EMSA) demonstrated that both sites bind to SF-1. Mutation of both sites significantly decreased the activity of -214/+47 promoter in Y1 cells. Transfection of SF-1-expressing plasmid into non-adrenal cells significantly increased the promoter activity, suggesting that SF-1 plays a role in the tissue-specific expression of human ACTHR gene. We identified the region, -764 to -503, that was required for the forskolin/cAMP responsiveness of the promoter. This region contains one AP-1 site. EMSA revealed that the binding of AP-1 to this site increased significantly upon treatment of Y1 cells with forskolin. Mutation of the site abolished the forskolin-responsiveness. In non-adrenal cells, the forskolin-responsiveness was observed only when SF-1-expressing plasmid was cotransfected. This is the first demonstration that both AP-1 and SF-1 are required for the cAMP-dependent induction of human ACTHR gene.

Animals↗

PubMed2000

[Early management of acute myocardial infarction in the elderly].

UNLABELLED: The efficacy of reperfusion treatment has been established in patients with acute myocardial infarction (AMI), however, its role is still controversial in the elderly patients. Data from Kochi Acute Myocardial Infarction Registry, consisting of 1,248 cases, showed that, compared to younger patients, elderly patients had greater ratio of women, painless infarction, delayed presentation, worse Killip classes, lower reperfusion procedure and higher mortality. To clarify the early management of AMI in the elderly, we analyzed the clinical data of 1,160 cases, according to age subgroup (317 advanced elderly, aged 75-84; 438 elderly, aged 65-74; 405 middle-aged, aged 45-64) and according to the period (term I, 1990-92; term II, 1993-95; term III, 1996-98). RESULTS: 1) The advanced elderly received less reperfusion treatment (37% vs. 65%) and showed higher mortality (21% vs. 8%), compared to middle-aged patients. 2) In advanced elderly patients, mortality was reduced (term I, 27%; term II, 20%; term III, 19%), according to increasing application of reperfusion treatment (term I, 22%; term II, 45%; term III, 40%). 3) Inoadvanced elderly patients with reperfusion treatment, thrombolysis resulted in a higher mortality (17% vs. 7%) compared to direct angioplasty, probably due to increased incidence of cardiac rupture and pump failure in this age group. CONCLUSIONS: Reperfusion treatment improves mortality of AMI even in elderly patients. To minimize complications, direct angioplasty may be better for elderly patients.

Age Factors↗

PubMed2000

Efficacy of cholesterol-lowering treatment in Japanese elderly patients with coronary artery disease and normal cholesterol level using 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor.

The clinical benefit of cholesterol-lowering treatment is unknown in the Japanese elderly in whom the prevalence of morbidity and mortality related to coronary artery disease are known to be low. To evaluate the efficacy of cholesterol-lowering treatment with 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor in Japanese elderly patients with documented coronary artery disease, 121 patients with serum cholesterol > or = 150 mg/dl prospectively received HMG-CoA reductase inhibitor, and 271 patients undergoing cholesterol-lowering treatment based on dietary therapy alone served as historical controls. The 143 elderly patients age > or = 65 years in the 2 groups had similar baseline serum total cholesterol level (201 +/- 30 vs 202 +/- 31 mg/dl), age (71 +/- 4 vs 70 +/- 4 years), proportion of men (37/53 vs 64/90), number of diseased vessels (1.7 +/- 0.9 vs 1.5 +/- 1.0), and incidences of other classical coronary risk factors, including hypertension, diabetes mellitus, smoking, obesity and family history of coronary artery disease. In all 392 patients, similar trends were observed, including serum total cholesterol level (208 +/- 33 vs 201 +/- 34 mg/dl). With HMG-CoA reductase inhibitors, serum total cholesterol level was reduced by 14% in the elderly subjects and by 13% in all patients. During the follow-up of approximately 3 years, cardiac events occurred in 5 patients (one elderly) in the treatment group and 38 patients (12 elderly) in the control group. Kaplan-Meier survival estimates revealed a higher event-free survival rate with HMG-CoA reductase inhibitors in the elderly subjects (98% vs 85%, p < 0.05) and in all patients (94% vs 86%, p < 0.05). Cox proportional hazard modeling also demonstrated a significant reduction in risk for cardiac events with drug therapy (relative risk 0.32, p < 0.05), in addition to the number of diseased vessels (relative risk 1.8, p < 0.01). In contrast, no additional risk was observed with advancing age. Cholesterol-lowering treatment with HMG-CoA reductase inhibitors is effective to improve the prognosis of Japanese elderly patients, including those with normal serum cholesterol level.

Anticholesteremic Agents↗

PubMed2000

[Evaluation of lung lobar ventilation dynamics with magnetic resonance imaging: a comparison of interstitial pneumonia patients with normal subjects].

Magnetic resonance imaging (MRI) was utilized to study lung lobar dynamic ventilation in 11 patients with interstitial pneumonia (IP) and 10 non-smoking men. The IP patients included 7 with interstitial lung disease associated with collagen vascular disease, 3 with idiopathic interstitial pneumonia, and 1 with lung cancer who was excluded from statistical analysis. We calculated lung lobar volumes in each phase from each dynamic image and constructed time-volume curves(TVCs). Lung lobar volume rates(%), fluctuation rates(%), lobar fluctuation rate/total lung fluctuation rate (%), and time lag (sec.) for the IP patients and normal subjects were calculated and compared. In the former, the mean volume rate for the right upper lobe was larger (p < 0.01) than that in normal subjects. The mean volume rate for the left lower lobe in the IP patients was smaller(p < 0.01) than that in the normal subjects. In IP patients, peak TVC for the right middle lobe appeared later (p < 0.01) than that in normal subjects. Although the fluctuation rates and fluctuation rate/total lung fluctuation rate for the lower lobes tended to be higher than those for the upper and middle lobes in normal subjects, this tendency was not distinct in IP patients. The quantitative evaluation of pulmonary ventilation dynamics with MRI may be a useful noninvasive technique for the assessment of lung lobar ventilation in patients with IP.

Adult↗

PubMed2000

Changes in calcium, PTH and 1,25(OH)2 vitamin D3 during tail-suspension in ovariectomized rats: effects of estrogen administration.

It is well known that estrogen deficiency results in osteoporosis in human and experimental animals. However, how its deficiency affects the development of disuse atrophy is not well understood. We thus investigated how estrogen deficiency caused by ovariectomy and estrogen supplements affect serum levels of calcium, parathyroid hormone (PTH), and 1,25-dihydroxy vitamin D3 (1,25(OH)2D3) in tail-suspended rats. Five-week-old female Wistar rats were ovariectomized and divided into two groups. One group received an intramuscular injection of estradiol dipropionate once a week (OVX-E2 group), and the other received the vehicle alone (OVX group). After the third injection, the rats were subjected to tail-suspension in metabolic cages for 1, 3, 5 or 7 days. In the OVX group, urinary excretion of deoxypyridinoline (D-Pyr) tended to increase on day 1 after tail-suspension. In the OVX-E2 group, basal excretion was lower than that in the OVX group, and no increase was observed after the suspension. Serum concentrations of ionized calcium significantly increased on day 1 after the suspension in both groups. However, in the OVX-E2 group, the level tended to be higher than those in the OVX group from day 0 to day 3. Serum PTH tended to decrease on day 1 after suspension in the OVX group. In the OVX-E2 group, it did not change during the suspension, but the levels were higher than those in the OVX group during the experiment. Serum 1,25(OH)2D3 transiently and significantly increased on day 1 after suspension in both groups. However, in the OVX group, the level was significantly higher than that in the OVX-E2 group. These data indicate that estrogen treatment of ovariectomized rats modifies the changes in calcium metabolism induced by tail-suspension.

Amino Acids↗

PubMed2000

Effect of estrogen and tail-suspension on expression of osteocalcin mRNA in femur of ovariectomized rats.

We investigated the effect of estrogen (E2) and tail-suspension on expression of osteocalcin (OC) mRNA in the femur of ovariectomized rats. Five-week-old female Wistar rats were ovariectomized and divided into two groups: one group received estradiol dipropionate (OVX-E2), and the other received the vehicle (OVX). Each group was further divided into two subgroups, tail-suspended (S) and non-suspended (N), giving a total of four groups: OVX-E2-S, OVX-E2-N, OVX-S and OVX-N. After a 7-day suspension, femurs were excised, and OC mRNA levels were determined by Northern blot analysis. A significant decrease of OC mRNA in OVX-E2-N was observed when compared with that of OVX-N, indicating that E2 decreases the OC expression. Interestingly, tail-suspension further decreased the mRNA levels in both OVX-S and OVX-E2-S when compared with the levels of OVX-N and OVX-E2-N, respectively. Since glucocorticoids have been shown to decrease OC expression, we also measured the urinary excretion of corticosterone during the suspension period that reflects the serum levels of corticosterone, and found that it was increased by E2 and further increased by tail-suspension. These results indicate that estrogen and glucocorticoids exert additive effects in inhibiting OC expression in the rat femur.

Animals↗

PubMed2000

Rotation in clinostat results in apoptosis of osteoblastic ROS 17/2.8 cells.

Clinostat is an effective, ground-based tool which can be used to verify data from space flight, and to test hypotheses and experimental conditions for eventual space flights. Rotation in clinostat appears to mimic the microgravity environment by nulling the gravitational vector by continuous averaging. In the present study, we exposed osteoblast-like ROS 17/2.8 cells to a vector-averaged gravity environment in a clinostat and found that the cells undergo apoptotic death during the first 24 hr of clino-rotation. We suggest that apoptosis might be one of the mechanisms for reduced bone formation as observed in actual space flights.

Apoptosis↗

PubMed1999

Expression of E16/CD98LC/hLAT1 is responsive to 2,3,7,8-tetrachlorodibenzo-p-dioxin.

We employed cDNA representational difference analysis to identify new genes that are upregulated by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in a human hepatoblastoma cell line HepG2. We isolated several TCDD-responsive cDNAs. Sequence analysis revealed that one of them encodes E16/CD98LC/hLAT1, an integral membrane protein involved in multiple cellular functions including cellular transport of L-type amino acids. Northern blot analysis confirmed the TCDD-dependent upregulation of the mRNA. Induction of E16/CD98LC/hLAT1 mRNA by TCDD did not require de novo protein synthesis as revealed by the experiment using cycloheximide. Consistent with the changes at mRNA level, the transport of 3H-leucine into HepG2 cells was significantly increased by TCDD treatment. These findings provide a novel aspect of biological effects of TCDD on human hepatocytes.

Amino Acid Transport Systems↗