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Biomedical subjects

H Seo

Publications and source records attributed to H Seo.

At least 109 records · Page 6Linked to original sources
PubMed1997

Effect of estrogen on the development of disuse atrophy of bone and muscle induced by tail-supension in rats.

Rat tail-suspension induces disuse atrophy of muscles and bones in hindlimbs. In the present investigation we studied how ovariectomy and estrogen substitution affect the development of the disuse atrophy induced by suspension. Five-week old female Wistar rats were ovariectomized and divided into two groups. One group received intramuscular injection of estradiol dipropionate once a week (OVX-E2 group), and the other received a vehicle injection (OVX group). After the third injection, each group was further divided into two groups, tail-suspended and non-suspended. After 7 days of tail-suspension, a significant decrease in the wet weight of femurs and their Ca and Pi content was observed in the OVX group. However, no significant change in those parameters was observed in the E2 group. In both E2 and OVX groups, a significant decrease in the wet weight of soleus and gastrocnemius muscles was demonstrated after the suspension. This demonstrated that estrogen administration to ovariectomized rats prevents the development of disuse bone atrophy but not that of muscle atrophy, suggesting that estrogen plays important roles in bone remodeling.

Animals↗
PubMed1997

Effect of bisphosphonate administration on the excretion of stress hormones in tail-suspended rats.

We demonstrated that administration of a bisphosphonate, YH529, prevents the development of disuse atrophy of the hind limbs induced by tail-suspension in rats. Since tail suspension is accompanied by an increase in the secretion of stress hormones, we studied whether administration of bisphosphonate affects the secretion of stress hormones during that procedure. Tail suspension was carried out in a metabolic cage by connecting a wire inserted through tail bone to the ceiling of the cage. The control rat received the same treatment but was not suspended. YH529 or a vehicle (PBS=phosphate buffered saline) was administered daily starting 3 days before the commencement of tail suspension. Urine samples were collected before the wire was inserted (day 0), on the day of insertion (day 1) and 3, 5 and 7 days after. In the control rats receiving PBS, urinary excretion of corticosterone and epinephrine did not change throughout the 7-day experimental period. In the control rats receiving YH529, urinary excretion of corticosterone increased significantly on the day of tail-piercing and wiring but then returned to the prior level. This increase was not observed in the control group receiving PBS. In the tail suspended rats, excretion of corticosterone and epinephrine increased significantly in both PBS and YH529 groups, the highest level being observed on the first day of tail suspension. Although statistically not significant, corticosterone excretion on day 1 of tail suspension was higher in the YH529 groups than that in the PBS group. It is thus suggested that administration of YH529 causes an augmented response to stress load.

Animals↗
PubMed1997

Administration of bisphosphonate prevents disuse bone atrophy induced by tail suspension.

We recently demonstrated that osteopenia induced by rat tail-suspension was associated with an initial increase in bone resorption. To study the significance of the increase in early bone resorption for osteopenia, we investigated whether administration of YH529, a third-generation bisphosphonate, prevents the development of osteopenia as evidenced by increased wet weight of the femur, together with its calcium and phosphorus contents, when compared with those of tail-suspended rats treated with the vehicle alone. These results suggested that the initial increase in bone resorption plays an important role in the development of osteopenia induced by tail suspension.

Animals↗
PubMed1997

[Surgically treated unruptured sinus of Valsalva aneurysm: a case report].

A 73-year-old man was admitted because of progressive dyspnea. Echocardiography revealed a markedly dilated right sinus of Valsalva and severe aortic regurgitation. Coaptation loss of the aortic valve leaflets was thought to be the cause of regurgitation and congestive heart failure, a rare complication of the unruptured sinus of Valsalva aneurysm. Surgical treatment should be considered to prevent life-threatening heart failure and rupture of the aneurysm even in patients without overt heart failure.

Aged↗
PubMed1997

Reduction in heart rate variability in patients with systemic lupus erythematosus.

OBJECTIVE: To determine whether heart rate variability and cardiovascular reflex tests are abnormal in patients with systemic lupus erythematosus (SLE). METHODS: We measured heart rate variability (24 h ambulatory recordings), and used baroreflex sensitivity testing and cardiovascular reflex tests in a cross sectional, case-control study. Those taking drugs with cardiovascular activity were excluded. RESULTS: Determination of heart rate variability was simple to perform, well tolerated, and found to be reduced in the patients with lupus, but not strongly related to disease activity or duration. CONCLUSION: This may reflect underlying autonomic dysfunction; longitudinal studies will determine full clinical relevance.

Adult↗
PubMed1997

Quercetin, a bioflavonoid, inhibits the induction of interleukin 8 and monocyte chemoattractant protein-1 expression by tumor necrosis factor-alpha in cultured human synovial cells.

OBJECTIVE: Tumor necrosis factor (TNF)-alpha is present in synovial fluid of patients with rheumatoid arthritis. It induces the expression of proinflammatory cytokines in synovial cells. Based on our recent finding that reactive oxygen intermediates play important roles in mediating TNF-alpha action, we examined the effect of an antioxidant bioflavonoid, quercetin, on TNF-alpha induced expression of interleukin 8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1) in cultured human synovial cells. METHODS: The amounts of mRNA for IL-8 and MCP-1 were determined by Northern blot analysis. Electrophoretic mobility shift assays (EMSA) were performed for the detection of a transcription factor, nuclear factor-kappa B (NF-kappa B). RESULTS: Addition of quercetin suppressed TNF-alpha induced increase in the mRNA for IL-8 and MCP-1 in a dose dependent manner. Quercetin did not affect the stability of these mRNA. H2O2 mediated induction of IL-8 and MCP-1 genes was also inhibited by quercetin. EMSA revealed that quercetin inhibited the activation of NF-kappa B by TNF-alpha. CONCLUSION: Quercetin suppresses TNF-alpha mediated stimulation of IL-8 and MCP-1 expression, at least in part, by inhibiting the activation of NF-kappa B.

Arthritis, Rheumatoid↗
PubMed1997

[Construction of pulmonary time-volume curve using MR: comparison with lung volume measurements using CT].

This study was conducted to investigate the effectiveness of dynamic pulmonary ventilation using MR and to compare it with lung volume measurements using CT. MR images during tidal breathing and CT images at resting expiratory level were obtained in 7 normal volunteers. The correlation between lung volume using CT and that using MR at resting expiratory level was significant (r = 0.993, p < 0.001). Pulmonary time-volume curves for each lobe were constructed by applying a Fourier series. The technique used in this study appears to be potentially useful to assess lobar lung function non-invasively and quantitatively.

Adult↗
PubMed1997

Indoxyl sulfate increases the gene expressions of TGF-beta 1, TIMP-1 and pro-alpha 1(I) collagen in uremic rat kidneys.

We recently reported that the serum levels of indoxyl sulfate, a dietary protein metabolite, are increased in both uremic rats and patients, and that the administration of indoxyl sulfate to uremic rats accelerates the progression of glomerular sclerosis. Thus, we hypothesize that the overload of protein metabolites such as indoxyl sulfate on nephrons promotes the progression of chronic renal failure (CRF). Recent studies revealed that tubulointerstitial injury is of equal or greater importance than glomerular sclerosis in determining whether progressive renal dysfunction will ensue in various renal diseases. In the present study, to clarify the role of indoxyl sulfate in the progression of CRF, the expressions of genes related to tubulointerstitial fibrosis such as transforming growth factor (TGF)-beta 1, tissue inhibitor of metalloproteinases (TIMP-1) and pro-alpha 1(I) collagen were examined in the renal cortex of 5/6-nephrectomized uremic rats given indoxyl sulfate. In the first experiment, the administration of indoxyl sulfate for five weeks significantly increased the mRNA levels of TGF-beta 1, TIMP-1 and pro-alpha 1(I) collagen in the uremic rats given indoxyl sulfate compared with the control uremic rats, accompanied by a significant decline in renal function and worsening of glomerular sclerosis. In the second experiment, the administration of indoxyl sulfate for 2.5 weeks also increased the expression of the mRNA levels with no significant decline in the renal function. In conclusion, these findings indicate that the overload of the protein metabolite indoxyl sulfate on remnant nephrons is involved in the increased bioactivity of TGF-beta 1 in uremic kidneys, which enhances the renal expression of TIMP-1 and type 1 collagen, leading to the progression of CRF.

Administration, Oral↗
PubMed1997

Indoxyl sulfate stimulates renal synthesis of transforming growth factor-beta 1 and progression of renal failure.

We recently demonstrated that the administration of indoxyl sulfate (dietary protein metabolite) to 5/6-nephrectomized rats accelerated the progression of chronic renal failure by increasing the transforming growth factor (TGF)-beta 1 synthesis in the kidneys, which enhanced the renal expressions of tissue inhibitor of metalloproteinase (TIMP)-1 and type 1 collagen, leading to renal fibrosis. The aim of the present study was to clarify the mechanism by which the administration of indoxyl sulfate increases TGF-beta 1 in the kidneys of uremic rats. Since infiltrative monocytes are suggested to be an important source of TGF-beta 1 in tubulointerstitial fibrosis, we examined the effect of indoxyl sulfate administration to uremic rats on the renal gene expression of intercellular adhesion molecule (ICAM)-1, which is involved in the infiltration of monocytes to kidneys. Indoxyl sulfate administration was observed to enhance the mRNA levels of ICAM-1 as well as those of TGF-beta 1, TIMP-1 and pro alpha 1 (I) collagen in the renal cortex of 5/6-nephrectomized uremic rats. In addition, we demonstrated in vitro that the addition of indoxyl sulfate significantly increased the synthesis of TGF-beta 1 in cultured proximal tubular cells. Thus, the overload of indoxyl sulfate in uremic kidneys increased the infiltration of monocytes and directly increased the synthesis of TGF-beta 1 in proximal tubular cells.

Animals↗
PubMed1996

Diagnostic significance of an exercise-induced prominent U wave in acute myocardial infarction.

A prominent U wave induced by exercise testing in patients with anterior wall myocardial infarction is a highly specific but insensitive marker for the narrowing of the left circumflex or right coronary artery, although a U-wave increase alone with or without ST-segment depression may help better identify these coronary artery narrowings. In patients with inferior and/or posterior myocardial infarction, a prominent U wave is regarded as a simple electrocardiographic marker for inferior and/or posterior residual ischemia.

Adult↗
PubMed1996

Heterodimerization preferences of thyroid hormone receptor alpha isoforms.

Thyroid hormone receptors (TRs) are members of the steroid hormone receptor superfamily and are encoded by two different genes, alpha and beta. Three isoforms (alpha 1, alpha 2, and alpha 3) are created by alternative splicing of the TR alpha gene. In TR alpha 2 and alpha 3, the distal half of the putative dimerization domain is disrupted and the carboxy terminus of the protein is substituted with different amino acids. To evaluate the properties of these alterations in the dimerization region, DNA binding and dimerization of TR alpha isoforms were studied by electrophoretic mobility shift assays. TR alpha 1 formed a monomer or a homodimer on certain thyroid hormone responsive elements (TREs), whereas TR alpha 2 and alpha 3 did not bind effectively to any of the TREs studied. TR alpha 1 formed a heterodimer with 9-cis retinoic acid receptor alpha (RXR alpha) on all TREs studied. Although TR alpha 2 did not bind as a homodimer, it did bind as a heterodimer with RXR alpha to DR4 and MHC-TRE. TR alpha 3 bound as a heterodimer to a broader repertoire of TREs, including DR4, MHC, ME, and F2-TRE. These results indicate that the alterations in the dimerization region in TR alpha 2 and alpha 3 abrogated homodimer binding, but differentially affected heterodimerization with RXR alpha on various TREs.

Amino Acid Sequence↗
PubMed1996

Multiple protein factors interact with the cis-regulatory elements of the proximal promoter in a cell-specific manner and regulate transcription of the dopamine beta-hydroxylase gene.

The dopamine beta-hydroxylase (DBH) gene is expressed selectively in noradrenergic and adrenergic neurons and neuroendocrine cells in the nervous system. A cAMP response element (CRE) residing at -181 to -174 bp from the transcription start site of the human DBH gene seems to be essential for DBH transcription. Potential cis-regulatory motifs such as AP1 and YY1 occur proximal to and overlap this CRE, endowing the area with a composite promoter structure. Using the DBH-expressing human neuroblastoma SK-N-BE(2)C and DBH-negative HeLa cell lines as model systems, we report here that this CRE/YY1/AP1 area interacts with multiple nuclear proteins, including CRE-binding protein (CREB) and transcription factor YY1 in a cell-specific manner. In support of the notion that multiple proteins bind to the CRE/YY1/AP1 area, DNase I foot-printing analysis has demonstrated that nuclear extracts protect an extended region (from -186 to -150 bp) relative to that protected by the purified CREB (from -186 to -171 bp). Site-directed mutational analysis has revealed differential roles of potential cis-regulatory motifs in regulation of DBH transcription. Strikingly, the YY1 element positively regulated basal DBH transcription while simultaneously regulating cAMP-mediated induction negatively, which is a novel mechanism of promoter function. Furthermore, three additional DNA-binding sites have been identified by DNase I footprint analysis in the upstream 260 bp promotor region of the human DBH gene, of which two sites are cell-specific. These results support a model whereby multiple proteins bind to the 5'-proximal area in a cell-specific manner and coordinately regulate the cell type-specific transcriptional activation of the DBH gene.

Base Sequence↗
PubMed1996

Molecular cloning of a novel thyroid hormone-responsive gene, ZAKI-4, in human skin fibroblasts.

Utilizing a method called "differential display of mRNAs by means of polymerase chain reaction", the cDNA fragment of a thyroid hormone-responsive gene ZAKI-4 was cloned from cultured human skin fibroblasts. Northern blot analysis revealed that there were two ZAKI-4 mRNA species (3.4 and 1.4 kilobases (kb)), and they were up-regulated by a physiological concentration of triiodothyronine (T3). This T3 effect was abolished by the treatment with cycloheximide, indicating the possibility that gene ZAKI-4 is regulated by T3 in an indirect fashion, through an intermediate product of T3, rather directly by T3 itself. No effect of T3 on ZAKI-4 mRNA stability suggested that T3 induces the mRNA at the transcriptional level. Rapid amplification of cDNA ends confirmed the presence of two mRNA species. ZAKI-4 mRNA was detected in heart, brain, liver, and skeletal muscle but not in placenta, lung, kidney and pancreas. In skin fibroblasts and skeletal muscle, 3.4-kb mRNA was the major species, whereas 1.4-kb mRNA was dominant in heart, brain, and liver. The sequence analysis suggested that the two mRNA species arise from alternative polyadenylation and code a single protein of 192 amino acids. No homologous protein sequence was found in a data base. Elucidation of the function of ZAKI-4 gene product will provide new insights into an important role of T3 in various organs.

Adolescent↗
PubMed1996

Second zinc finger mutants of thyroid hormone receptor selectively preserve DNA binding and heterodimerization but eliminate transcriptional activation.

Transcriptional regulation by thyroid hormone is mediated through its nuclear receptors (TRs), which bind to target responsive elements as homodimers or as heterodimers with 9-cis retinoic acid receptors (RXRs). We examined the dimerization and functional properties of TRs containing mutations in the first and second zinc finger regions of the DNA binding domain. Interestingly, a mutation (R158G) in the loop of second zinc finger, or a chimeric mutant in which the second zinc finger of the glucocorticoid receptor (GR) was substituted for that of the TR, did not form homodimer, but still bound as a heterodimer with RXR alpha. Despite the presence of heterodimer formation, these mutants were functionally inactive in transfection assays. We conclude that sequences within the loop of the second zinc finger may play an important role in stability in vivo or transcriptional activation of the TR.

Amino Acid Sequence↗
PubMed1996

IL-13 and IL-4 inhibit bone resorption by suppressing cyclooxygenase-2-dependent prostaglandin synthesis in osteoblasts.

Activated T cells secrete the cytokine IL-13, which regulates inflammatory and immune responses. To explore the role of IL-13 in bone metabolism, we examined the effects of the cytokine on bone resorption and PG synthesis in osteoblasts. IL-13 suppressed the bone-resorbing activity stimulated by IL-1 alpha, which was determined by the release of 45Ca from prelabeled mouse long bones. Histologic examinations revealed that IL-1 alpha markedly stimulated bone resorption with increased osteoclast recruitment, and that the simultaneous addition of IL-13 considerably inhibited it. The gamma-chain of IL-2 receptors may be functionally involved in the signal transduction of not only IL-2, but also IL-4, IL-7, and IL-13. Of these cytokines, IL-4 similarly suppressed IL-1 alpha-induced bone resorption, but IL-2 and IL-7 did not. Both IL-13 and IL-4 inhibited PGE2 production stimulated by IL-1 alpha in long bone cultures. Suppression of IL-1 alpha-induced bone resorption by IL-13 and IL-4 was recovered by adding exogenous PGE2 to the long bone cultures. Neither IL-4 nor IL-13 further inhibited IL-1 alpha-induced bone resorption in the presence of indomethacin. To examine the effects of IL-13 on PG synthesis, we measured the mRNA levels of cytosolic phospholipase A2 (cPLA2), constitutively expressed cyclooxygenase (COX-1) and inducible COX (COX-2) in mouse osteoblast-like cells. IL-1 alpha markedly stimulated the mRNA expression of COX-2, but not that of COX-1. Both IL-13 and IL-4 dose-dependently suppressed the IL-1 alpha-induced stimulation of both COX-2 mRNA expression and PGE2 synthesis. A small increase (1.7-fold) in cPLA2 mRNA levels was detected in the cultures with IL-1 alpha, but the expression was not affected by IL-13 or IL-4. These results indicated that IL-13 and IL-4 inhibit bone resorption by suppressing COX-2-dependent PG synthesis in osteoblasts.

Animals↗
PubMed1996

Ultrastructure of hepatocytes in copper-deficient Sika deer (Cervus nippon Temminck).

The livers of 13 Sika deer (Cervus nippon Temminck) aged 4 to 9 years and suffering from copper deficiency (enzootic ataxia) were examined histologically, histochemically and by electron microscopy. In addition, the serum and liver copper concentrations, measured in three animals, were found to be low. Histologically, the hepatocytes exhibited cloudy swelling, and numerous haemosiderin deposits were seen in the hepatocytes and Kupffer cells. Staining with p-dimethyl amino-benzylidene-rhodamine revealed distinctly fewer copper granules than normal. Histochemically, 3,3'-diaminobenzidine-H2O2 staining revealed increased numbers of catalase-positive granules around nuclei. Electron microscopically, "giant" and bizarre-shaped mitochondria, irregular depression of the mitochondrial membrane, and fusion of cristae were noted. Disorders of copper-containing enzymes, including cytochrome oxidase, caeruloplasmin and monoamine oxidase, may have been responsible for the mitochondrial abnormalities.

Animals↗
PubMed1996

Monocyte/macrophage response to beta 2-microglobulin modified with advanced glycation end products.

We recently found that acidic beta 2-microglobulin (beta 2m), a major isoform of beta 2m in amyloid fibrils of patients with dialysis-related amyloidosis (DRA), contained early Amadori products and advanced glycation end products (AGEs) formed nonenzymatically between sugar and protein. Further analysis revealed that acidic beta 2m induces monocyte chemotaxis and macrophage secretion of bone-resorbing cytokines, suggesting the involvement of acidic beta 2m in the pathogenesis of DRA. Acidic beta 2m, however, is a mixture of heterogeneous molecular adducts due to various types of modification. In the present study, we investigated the modification responsible for the biological activity of acidic beta 2m toward monocytes/macrophages. The presence of a fair amount of beta 2m species with deamidation was detected in acidic beta 2m isolated from urine of non-diabetic long-term hemodialysis patients, but deamidated beta 2m had no biological activity. In contrast, normal beta 2m acquired the activity upon incubation with glucose in vitro. Among the glycated beta 2m, the pigmented and fluorescent beta 2m that formed after a long incubation period, that is, AGE-modified beta 2m, exhibited biological activity, whereas beta 2m modified with Amadori products, major Maillard products in acidic beta 2m, had no such activity. These findings suggest that AGEs, although only a minor constituent of acidic beta 2m, are responsible for monocyte chemotaxis and macrophage secretion of cytokines, implicating the contribution of AGEs to bone and joint destruction in DRA.

Adult↗