Biomedical subjects

Ming-Ju Chuang

Publications and source records attributed to Ming-Ju Chuang.

9 recordsLinked to original sources

PubMed2006

Blockade of endothelin-1 release contributes to the anti-angiogenic effect by pro-opiomelanocortin overexpression in endothelial cells.

Pro-opiomelanocortin (POMC) is the precursor of several neuropeptides, such as corticotropin (ACTH), alpha-melanocyte-stimulating hormone (MSH), and the endogenous opioid, beta-endorphin (EP). ACTH-dependent Cushing's syndrome is characterized by ACTH overproduction and is associated with an increased risk of cardiovascular disease. Endothelial dysfunction has been recognized as an early marker of cardiovascular disease. However, the mechanism underlying endothelial dysfunction by ACTH overexpression in Cushing's patients remains elusive. Endothelial cells, the primary cells producing endothelin (ET)-1, are both the source and target of POMC-derived peptides. In the present study, we generated adenovirus vectors (Ad) encoding POMC (Ad-POMC) and green fluorescent protein (GFP; Ad-GFP) to investigate whether POMC gene transfer altered the ET-1 homeostasis and angiogenic functions in human EA.hy926 endothelial cells. Via adenovirus gene delivery, the POMC-transduced EA.hy926 cells released significantly elevated ACTH and beta-EP levels (P < 0.001). In addition, POMC gene delivery significantly decreased the ET-1 release (P < 0.001) without affecting the ET-1 messenger RNA (mRNA) level. Despite no effect on the secretion of matrix metalloproteinases (MMPs) and cell proliferation, POMC gene delivery significantly inhibited the migration (P < 0.01) and tube-forming capability (P < 0.01) of endothelial cells. Moreover, the POMC-induced inhibition of tube formation could be partially reversed by adding exogenous ET-1 (P < 0.05). In summary, the attenuated ET-1 release and angiogenic processes by POMC overexpression may contribute to endothelial dysfunction, thereby providing a link between Cushing's syndrome and cardiovascular diseases.

Adenoviridae↗

PubMed2006

The effects of different doses of atorvastatin on plasma endothelin-1 levels in type 2 diabetic patients with dyslipidemia.

We investigated the effects of three different daily doses (10 mg, 20 mg, and 40 mg) of atorvastatin, a relatively new and potent statin, on plasma endothelin (ET)-1 and highly sensitive C-reactive protein (CRP) levels in type 2 diabetic subjects. Twenty-nine type 2 diabetic patients with dyslipidemia were enrolled and randomly assigned to receive atorvastatin orally at 10 mg (A10; n = 10), 20 mg (A20; n = 10), or 40 mg (A40; n = 9) daily for 12 weeks. Levels of plasma total cholesterol and low-density lipoprotein (LDL)-cholesterol (C) in all three studied groups were significantly decreased after treatment with atorvastatin for 12 weeks (all groups, P < 0.001). However, the greatest LDL-C lowering effect and the highest percentage of subjects achieving the National Cholesterol Education Program's Adult Treatment Panel III (NCEP-ATP III) LDL-C goal were observed in the A20 group. All diabetic subjects had a higher plasma ET-1 concentration (A10, 1.02 +/- 0.37 pg/ml, mean +/- SD; A20, 1.17 +/- 0.55 pg/ml; and A40, 0.87 +/- 0.45 pg/ml) than that of age- and sex-matched normal control subjects (0.64 +/- 0.15 pg/ml; all groups, P < 0.001). Plasma ET-1 levels showed a borderline significant decrease at the end of study, by 22% in diabetic subjects treated with 10 mg atorvastatin (P = 0.05 compared with baseline), and by 30% in subjects treated with 20 mg atorvastatin (P = 0.06, compared with baseline). Paradoxically, the 40-mg dose of atorvastatin provided an increase of 2% in plasma ET-1 levels at the end of study, which is significantly different (P < 0.05) and marginally significant (P = 0.057) from the levels of the 10- and 20-mg doses, respectively. Similarly, although insignificantly, plasma concentrations of CRP also tended to decrease by 12% and 48%, and paradoxically increased by 18% in diabetic patients treated with 10 mg, 20 mg, and 40 mg atorvastatin, respectively. The clinical significance of these biphasic lipid-independent statin effects is unknown and the present study suggests that 20 mg atorvastatin may have the best benefits in treating diabetic patients with dyslipidemia.

Adolescent↗

PubMed2006

Hyperthyroidism is associated with higher plasma endothelin-1 concentrations.

The objective of this study was to determine the change of plasma endothelin (ET)-1 concentrations and insulin resistance index after therapy for hyperthyroidism. We studied 20 patients with hyperthyroidism (15 women and 5 men; age, 34.0 +/- 2.8 years), and 31 patients with euthyroid goiters as controls (27 women, 4 men; age, 37.0 +/- 2.4 years). All hyperthyroid patients were treated with antithyroid drugs. The patients received evaluations before and after normalization of thyroid function. The evaluations included body mass index (BMI), body fat, and measurement of circulating concentrations of thyroid hormones, glucose, insulin, and ET-1. Hyperthyroid subjects had higher plasma ET-1 concentrations than the control group (P < 0.001). No significant differences in serum glucose and insulin concentrations or insulin resistance index estimated by the R value of the homeostasis model assessment (HOMA-R) were noted between the groups. Plasma ET-1 concentrations decreased after correction of hyperthyroidism compared with pretreatment (P = 0.006). Serum glucose concentrations decreased after correction of hyperthyroidism (P = 0.005). Moreover, both body weight-adjusted insulin concentrations and the HOMA-R index were also decreased after correction of hyperthyroidism compared with pretreatment (P = 0.026 and P = 0.019, respectively). Pearson's correlation revealed that plasma ET-1 levels positively correlated with serum triiodothyronine (T3) and free thyroxine (FT4) levels. Serum insulin levels and the HOMA-R index positively correlated with BMI and body fat. The HOMA-R index also positively correlated with serum T3 and FT4 levels. Neither insulin levels nor the HOMA-R index correlated with ET-1 levels. Hyperthyroidism is associated with higher plasma ET-1 concentrations. In addition, correction of hyperthyroidism is also associated with a decrease of plasma ET-1 levels as well as the insulin resistance index calculated by HOMA-R.

Adult↗

PubMed2005

Gene transfer of pro-opiomelanocortin prohormone suppressed the growth and metastasis of melanoma: involvement of alpha-melanocyte-stimulating hormone-mediated inhibition of the nuclear factor kappaB/cyclooxygenase-2 pathway.

Pro-opiomelanocortin (POMC) is a prohormone of various neuropeptides, including corticotropin, alpha-melanocyte-stimulating hormone (alpha-MSH), and beta-endorphin (beta-EP). POMC neuropeptides are potent inflammation inhibitors and immunosuppressants and may exert opposite influences during tumorigenesis. However, the role of POMC expression in carcinogenesis remains elusive. We evaluated the antineoplastic potential of POMC gene delivery in a syngenic B16-F10 melanoma model. Adenovirus-mediated POMC gene delivery in B16-F10 cells increased the release of POMC neuropeptides in cultured media, which differentially regulated the secretion of pro- and anti-inflammatory cytokines in lymphocytes. POMC gene transfer significantly reduced the anchorage-independent growth of melanoma cells. Moreover, pre- or post-treatment with POMC gene delivery effectively retarded the melanoma growth in mice. Intravenous injection of POMC-transduced B16-F10 cells resulted in reduced foci formation in lung by 60 to 70% of control. The reduced metastasis of POMC-transduced B16-F10 cells could be attributed to their attenuated migratory and adhesive capabilities. POMC gene delivery reduced the cyclooxygenase-2 (COX-2) expression and prostaglandin (PG) E(2) synthesis in melanoma cells and tumor tissues. In addition, application of NS-398, a selective COX-2 inhibitor, mimicked the antineoplastic functions of POMC gene transfer in melanoma. The POMC-mediated COX-2 down-regulation was correlated with its inhibition of nuclear factor kappaB (NFkappaB) activities. Exogenous supply of alpha-MSH inhibited NFkappaB activities, whereas application of the alpha-MSH antagonist growth hormone-releasing peptide-6 (GHRP-6) abolished the POMC-induced inhibition of NFkappaB activities and melanoma growth in mice. In summary, POMC gene delivery suppresses melanoma via alpha-MSH-induced inhibition of NFkappaB/COX-2 pathway, thereby constituting a novel therapy for melanoma.

Adenoviridae↗

PubMed2004

Immunoreactive endothelin in Taiwanese thyroid cystic fluid.

Endothelin-1 is a major vasoconstrictor peptide, first found in endothelial cells and later in many other tissues, including the thyroid gland. It is well known that endothelins can act as autocrine and/or paracrine regulators of thyroid homeostasis and growth. Previously we have demonstrated that immunoreactive endothelins (IR-ET) are present in various human body fluids, and IR-ET has also been detected in pathologic breast and thyroid cystic fluids. In this study, the IR-ET in Taiwanese thyroid cystic fluid was measured by radioimmunoassay and characterized by chromatography. Human thyroid cystic fluid was obtained by fine needle aspiration, was centrifuged, and the supernatant was stored at -20 degrees C until IR-ET assay. IR-ET has been detected in 25 of 33 samples of thyroid cystic fluid [25 cases, 4.11 +/- 0.31 fmol/mL (mean +/- standard error of the mean); other eight cases, undetectable]. Gel permeation chromatography of the extract of pooled cystic fluid showed only one major peak at the elution position of human endothelin-1 standard. No difference in cystic IR-ET levels was found in our patients with cystic nodules in relation to differences in thyroid function. It is probable that endothelin-1 is produced by the epithelial cells lining the thyroid cysts, and the increased levels of IR-ET in cystic fluid found in our patients could either be secondary to cystic nodule development or have a role in goiter formation.

Asian People↗

PubMed2004

Salivary immunoreactive endothelin in patients with upper gastrointestinal diseases.

Endothelins have been implicated in gastric mucosal damage in a variety of animal models. Furthermore, clinical reports also show elevated gastric mucosal endothelin-1 levels in patients suffering from peptic ulcer diseases. We have demonstrated, first, the presence of immunoreactive endothelin (IR-ET) in human saliva. We also show that endothelins are rather stable in human saliva. The present study was undertaken to determine whether patients with endoscopically proven upper gastrointestinal diseases have a salivary excess of IR-ET, compared with patients with a normal esophagogastroduodenoscopy. Saliva was collected from fasting subjects prior to esophagogastroduodenoscopy. The levels of IR-ET were measured by the radioimmunoassay method. The salivary concentrations of IR-ET in the studied subjects were as follows: 8.9 +/- 1.0 fmol/mL (mean +/- standard error of the mean) for patients with gastric ulcers (n = 18); 7.3 +/- 1.0 fmol/mL for patients with duodenal ulcers (n = 22); and 6.8 +/- 0.6 fmol/mL for patients with gastritis (n = 28). These values are all higher than that of normal subjects (4.4 +/- 0.5 fmol/mL, n = 20; P < 0.001, P < 0.01, and P < 0.05, respectively). No significant differences in salivary IR-ET were noted between patients with a normal esophagogastroduodenoscopy and patients with esophagitis (3.8 +/- 0.7 fmol/mL, n = 4) or gastric cancer (5.3 +/- 1.4 fmol/mL, n = 4). There were no significant differences in the salivary IR-ET levels between males and females. However, the salivary IR-ET levels in the smokers (8.0 +/- 0.6 fmol/mL, n = 38) were significantly higher (P < 0.01) than those of the non-smokers (6.0 +/- 0.4 fmol/mL, n = 58). There was no correlation of IR-ET levels with age. Our findings suggest that salivary endothelin may have a contributing role in certain gastroduodenal diseases.

Asian People↗

PubMed2003

Role of endothelin in diabetic retinopathy.

Endothelin-1 (ET-1) is a 21 amino acid peptide originally purified from conditioned medium of cultures of porcine aortic endothelial cells. It is now known that there are three endothelin genes in the human genome (ET-1, ET-2, and ET-3 genes). ET-1 and ET-2 are both strong vasoconstrictors, whereas ET-3 is a potentially weaker vasoconstrictor compared to the other two isoforms. Besides being a very potent vasoconstrictor, ET-1 also acts as a mitogen on the vascular smooth muscle and thus it may play a role in the development of vascular diseases. There is evidence that impaired auto-regulation of blood flow is involved in the pathogenesis of diabetic microangiopathy. It is known that the ability of the diabetic's circulation to distribute blood is affected, especially during increased blood flow. In most tissues this causes no serious burden, but three tissues are usually susceptible to disturbance. They are the retina, renal cortex, and peripheral nerves. Retinal vascular auto-regulation is defined as the ability of the blood vessels to keep blood flow constant under varying perfusion pressure in order to match it to tissue oxygen and metabolic requirements. The failure of auto-regulation is an important and often early feature of diabetic retinopathy. Since human retina vessels lack extrinsic innervation, retinal vessel calibre and local blood flow are normally regulated by non-nervous mechanisms intrinsic to the retina. There is now a considerable body of evidence suggesting that retinal pericytes are the main regulators of vascular tone in the retinal capillaries because they contain components of contractile proteins similar to vascular smooth muscle cells and because they also possess ET-1 receptors. Furthermore. ET-1 has been shown to cause vasoconstriction of retinal vessels as well as to have mitogenic effects on retinal pericytes. Hence, alterations in the pericyte-ET interaction may have a role causing early hemodynamic and histopathological abnormalities found in diabetic retinopathy. On the contrary, Chakrabarti et al. demonstrate that retinas from the chronic diabetic BB/W rats (6 months) show an increase in ET-1, ET-3, ET(A) receptor and ET(B) receptor mRNA expressions when compared to those from control rats. Similar results are noted by them using immunohistochemical methods. Finally, an increased ocular, and retina tissue levels of ET-1 in diabetic rats have also been reported by Chakravarthy et al., as well as by Takagi et al. All of these findings suggest that endothelins may also be involved in the pathogenesis of more advanced diabetic retinopathy, such as capillary occlusion and subsequent neovascularization. This review summarizes the reported literature on the role of ET-1 in the development of diabetic retinopathy.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed2003

Sclerotherapy of thyroid cystic nodules.

BACKGROUND AND PURPOSE: Percutaneous ethanol injection (PEI) has been established as an effective and safe treatment for thyroid cystic nodules (TCN). Certain tetracyclines have also been used successfully as sclerosing agents, and it has been proposed that a low pH might account for their efficacy in this indication. This study compared the effectiveness of ethanol and dilute hydrochloric acid (pH 1.0) in the sclerotherapy of TCN. METHODS: A total of 27 patients with TCN with a mean cystic volume of 16.6 mL (5-45 mL) were randomly assigned to receive 1 of the following 3 treatments: 1) needle aspiration only, 9 patients; 2) PEI, 10 patients; or 3) percutaneous hydrochloric acid injection (PHI), 8 patients. The procedures were performed weekly until cure was evident. Resolution was defined as the disappearance of cyst or reduction of cystic volume to below 0.5 mL. Treatment was considered a failure if the condition did not resolve after 5 sessions of intervention. The 10 original patients treated by PEI and 14 additional patients subsequently enrolled and treated by PEI were followed for 24 months in order to evaluate the long-term effects of PEI treatment. Follow-up physical examination and ultrasound scan was performed every 3 months during the first year and every 6 months during the second year. A cystic volume of greater than 1 mL was regarded as a recurrence. RESULTS: PHI did not have a better cure rate than aspiration alone (37.5% vs 44.4%, p = 0.778). PEI had a significantly higher cure rate than PHI (90% vs 37.5%, p = 0.023) and aspiration alone (90% vs 44.4%, p = 0.038). No patient who received aspiration only complained of cervical pain. Four patients who received PEI and 3 patients who received PHI complained of self-limited cervical pain soon after sclerosant injection. Completed follow-up in the 24 patients ranged from 3 to 24 months (mean, 15.5 +/- 7.7 months), and only 3 patients (12.5%) were found to have recurrence within the first 9 months. The likelihood of recurrence was not correlated with pretreatment cystic volume. CONCLUSIONS: Use of a low-pH sclerosant (PHI) was of no benefit. PEI provides a rapid, tolerable, and sustained effect and can be used as first-line treatment in patients with TCN.

Adult↗

PubMedDate not supplied

Two-year effect of rosiglitazone in chinese poorly controlled type 2 diabetic patients.

BACKGROUND: The goal of this study is to assess the 24-week efficacy of the addition of rosiglitazone 4 mg to existing full dose sulfonylurea (SU) and metformin (MET) therapy in patients with inadequately controlled type 2 diabetes, and to observe the continued follow-up efficacy and safety of this drug for up to two years. METHODS: This study consists of 32 patients. Fasting plasma glucose (FPG), free fatty acid (FFA), high sensitive C-reactive protein (HS-CRP), adiponectin, insulin and C-peptide were measured every four weeks up to week 24. After that time, the FPG continued to be checked every month. Glycated hemoglobin (HbA1c) and lipid profiles were also checked every 12 weeks for more than two years. RESULTS: HbA1c was reduced by 1.4% at week 12 and by 1.1% at week 24. However HbA1c was still above 9% throughout the whole study period. FPG was reduced significantly when comparing the baseline value to the value after treatment. The FPG values after one year and two years follow-up were similar to the value at week 24. The serum total cholesterol and low density lipoprotein (LDL) cholesterol levels increased significantly. Serum triglycerides were reduced significantly. Significant reductions in serum FFA from baseline to week 24 were observed. A gradually decrease of serum HS-CRP was noted from baseline to week 24. Serum adiponectin levels increased maximally at week 12 and then it decreased gradually, showing a significant change. Serum insulin and C-peptide levels showed significant changes from baseline to week 24. There were no acute cardiocerebral peripheral vascular disease events or liver damage within the entire study period. CONCLUSIONS: Clinical improvement in glycemic control was observed after the addition of rosiglitazone to type 2 diabetic patients receiving full dose SU and MET therapy. The maximal effect was observed at week 12 and the effect continued for at least two years. Further, the combination therapy also resulted in an improvement in lipid profiles, decreased HS-CRP and increased adiponectin levels in the short term (24 weeks). This combination therapy is also safe and beneficial for at least two years because no acute episodes of cardiocerebral peripheral vascular disease were seen.

Adiponectin↗