Justin G S Won

National Yang Ming University, T’ai-pei, Taipei, Taiwan

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Publications (26)47.34 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Peripheral arterial disease (PAD) could be an additional risk factor for the clinical outcomes in different populations. The purpose of this study was to evaluate the influence of PAD on patients with diabetic kidney disease. 362 persons with type 2 diabetes were followed-up for a mean 4.8 years grouped by ankle brachial index (ABI) (<0.9 vs. ≧0.9) and albuminuria (with or without). Primary and secondary outcomes were composite events (all-cause mortality, hospitalization for coronary artery disease, stroke, re-vascularization, amputation, and diabetic foot) and all-cause mortality. Inter-group differences in duration of diabetes, glycated hemoglobin, creatinine, and estimated glomerular filtration rate were significant. During the follow-up period, 53 composite events were recorded (14.7%) and 13 (3.5%) individuals died. Subjects with albuminuria plus ABI<0.9 had higher risk of composite events than those with albuminuria but normal ABI (p<0.05). The only trend difference between the two groups was in all-cause mortality. Albuminuria plus ABI <0.9 was associated with risk of composite events (hazard ratio [HR] 4.20, 95% confidence interval [CI] 1.77-9.92, p=0.001) and all-cause mortality (HR 17.77, 95% CI 1.93-162.20, p=0.011). PAD might be an additional risk factor for adverse outcomes in patients with diabetic kidney disease. Further prospective data are required to validate this conclusion. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
    Diabetes Research and Clinical Practice 02/2015; 108(2). DOI:10.1016/j.diabres.2015.02.001 · 2.54 Impact Factor
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    ABSTRACT: Objective: Patients with type 2 diabetes mellitus (T2DM) and peripheral arterial disease are classified as having very high cardiovascular risks. We therefore sought to determine whether assessments of the ankle brachial index (ABI) and brachial ankle pulse wave velocity (baPWV) together exhibited a superior association with the outcomes of T2DM. Methods: A retrospective analysis of patients receiving ABI and baPWV during the period 2005-2007 was performed. Patients A total of 452 subjects were enrolled and followed-up for a mean 5.8 years after being grouped according to the ABI (<0.9 vs. ≥0.9) and baPWV (<1,700 cm/s vs. ≥1,700 cm/s). Results: The outcomes were all-cause mortality and composite events (all-cause mortality, hospitalization for coronary artery disease, stroke, re-vascularization, amputation and diabetic foot). Inter-group differences in the smoking rate, duration of diabetes, systolic and pulse blood pressure, anti-platelet drugs, estimated glomerular filtration rate, and urine albumin excretion were significant. During the follow-up period, 17 (3.7%) individuals died and composite events were recorded in 64 cases (14.1%). A low ABI plus high baPWV was found be associated with poor outcomes compared with a normal ABI plus low baPWV (p<0.001). Meanwhile, a low ABI plus high baPWV was associated with an increased risk of all-cause mortality [hazard ratio (HR) 17.01, 95% confidence interval (CI) 1.57-183.73, p=0.019] and composite events (HR 8.53, 95% CI 3.31-21.99, p<0.001). Conclusion: In this study, the outcomes of patients with a low ABI plus high baPWV were the worst, while the subjects with a low ABI plus low baPWV or normal ABI exhibited similar outcomes. Therefore, the ABI plus baPWV exhibits a better association with the outcomes of T2DM.
    Internal Medicine 11/2014; 53(21):2425-31. DOI:10.2169/internalmedicine.53.2999 · 0.90 Impact Factor
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    ABSTRACT: Objectives Most patients with Cushing’s disease (CD) respond to corticotrophin-releasing hormone (CRH) or desmopressin with increased corticotrophin (ACTH) and cortisol levels. Although the vasopressin receptor subtype located on normal corticotrophs is the V3 receptor (V3R), desmopressin is a selective V2 receptor (V2R) agonist and it is unclear whether corticotrophinomas exhibit aberrant V2R expression. Furthermore, no studies have determined the relationship between the in vivo response of CD patients to desmopressin and vasopressin receptor expression, or between the response to CRH and CRH receptor (CRHR) expression. Therefore, the aim of this study was to investigate the expression of vasopressin receptors (V1R, V2R, and V3R) and CRHR on corticotroph tumours and its possible relation to the in vivo response. Designs A prospective study of 29 patients with CD. Methods Patients underwent desmopressin and CRH stimulation tests before surgery. The expression of vasopressin receptors and CRHR on corticotrophinomas was determined by immunocytochemistry. Results Most of the corticotrophinomas exhibited abundant expression of V1R, V3R, and CRHR, whereas the expression of V2R varied greatly and was lower in macroadenomas than in microadenomas. Both the percentage increment of ACTH and net area under the curve (AUC) of ACTH in the desmopressin stimulation test were found to be correlated with tumour volume. After adjustment for tumour volume, a positive correlation was found between the percentage increment of ACTH and the degree of V2R expression, but not between that of V1R or V3R. No relationship between the level of expression of CRHR on tumour tissues and the percentage increment or netAUC of ACTH to CRH was observed in CD patients. Conclusions We concluded that V2R was expressed on corticotrophinomas and that the level of its expression correlated well with the ACTH response to desmopressin in CD patients, although abundant expression of V1R and V3R was also found in almost all corticotroph tumours. Further studies are needed to elucidate the role of these receptors in the pathogenesis of CD.
    Clinical Endocrinology 07/2011; 76(2):253-63. DOI:10.1111/j.1365-2265.2011.04179.x · 3.46 Impact Factor
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    ABSTRACT: To determine the relationships between cardiovascular autonomic neuropathy (CAN) and autonomic symptoms, clinical parameters and diabetic complications in type 2 diabetes (T2DM). The results of autonomic symptoms, clinical parameters, diabetes complications and cardiovascular reflex (CVR) tests of 674 T2DM were analyzed. Significant correlations were found between CAN risk and age (p=0.019), duration of diabetes (p=0.008), HbA1c (p<0.001), systolic blood pressure (p=0.006), nephropathy (p<0.001), retinopathy (p<0.001), and QTc interval (p<0.001), but not BMI and hyperlipidemia. Patients with retinopathy or proteinuria had increase risk of CAN, and proliferative diabetic retinopathy (PDR) was the most significant risk factor (odds ratio: 6.85; 95% CI: 2.32-20.20) for CAN. Eighty-three percent of patients complained of autonomic symptoms; and the more symptoms complained, the higher the prevalence of CAN. Impotence was the only single symptom associated with CAN risk. Additional CAN risks were also observed when patients with multiple symptoms and/or complications in combinations. Our results implied that patients with multiple symptoms and/or complications in combinations have increased CAN risk, and this may provide additional information for clinicians to identify T2DM at risk of having CAN.
    Diabetes research and clinical practice 10/2008; 82(2):282-90. DOI:10.1016/j.diabres.2008.08.012 · 2.54 Impact Factor
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    ABSTRACT: The differential diagnosis of adrenocorticotropin (ACTH)-dependent Cushing's syndrome (CS) remains a challenging issue for clinical endocrinologists. In this respect, bilateral inferior petrosal sinus sampling (BIPSS) appears to be the most sensitive and specific test. Here, we report our 15-year experience of analyzing the performance of BIPSS, both in the correct diagnosis and in the precise lateralization of tumors in patients with Cushing's disease (CD). Between 1992 and 2006, 18 patients with CD (16 females, 2 males; age range, 14-56 years) were admitted to Taipei Veterans General Hospital and subjected to BIPSS plus ovine corticotropin-releasing hormone (oCRH) stimulation. Four of them had previously undergone transsphenoidal hypophysectomy (TSH) and had a recurrence thereafter. BIPSS was performed by inserting a catheter in the right and left inferior petrosal sinus for ACTH assay via a femoral vein puncture. An inferior petrosal sinus/peripheral ACTH ratio (C/P ratio) > or = 2 at baseline > or = 3 after oCRH injection indicated a pituitary origin of ACTH secretion, and an interpetrosal ACTH gradient (IPS ratio) > or = 1.4 at baseline or after oCRH indicated evidence of lateralization. Positive BIPSS results were found in 16 patients at baseline and in 17 patients after oCRH injection. In 17 out of 18 patients, TSH was subsequently carried out and a pituitary source was confirmed on histopathologic examination. The only 1 false-negative test result was noted in a patient who had undergone previous TSH. Thus, the sensitivities of BIPSS for the diagnosis of CD before and after oCRH stimulation were 89% and 94%, respectively. Moreover, using an IPS ratio > or = 1.4 as a criterion, BIPSS correctly lateralized the tumor in 9 of 17 and 10 of 17 patients at baseline and after oCRH stimulation, respectively, including in 2 patients who had a centrally located tumor and who had an IPS ratio < 1.4. Thus, the sensitivities of lateralization of BIPSS were 53% and 59%, respectively. None of the 4 patients who had previous TSH were precisely localized by BIPSS. If these 4 patients were excluded, the sensitivities of BIPSS for localizing in the patients who had not undergone previous operation increased to 70% (9/13) at baseline and 77% (10/13) after oCRH stimulation, respectively. BIPSS combined with oCRH stimulation is a safe and reliable examination both in the differential diagnosis of CD and in the correct lateralization of pituitary microadenoma in patients without previous pituitary surgery. Nevertheless, this procedure may provide misleading results in patients who have received previous pituitary surgery.
    Journal of the Chinese Medical Association 01/2007; 70(1):4-10. DOI:10.1016/S1726-4901(09)70293-X · 0.85 Impact Factor
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    ABSTRACT: Noninsulinoma pancreatogenous hypoglycaemia syndrome (NIPHS), characterized by postprandial neuroglycopaenia, negative prolonged fasts and negative perioperative localization studies for insulinoma, but positive selective arterial calcium stimulation tests and nesidioblastosis in the gradient-guided resected pancreas, is a rare hypoglycaemic disorder of undetermined aetiology. We analysed the clinical, morphological and immunohistological features to further clarify the aetiology and pathogenesis of this rare disease. Ten consecutive patients with NIPHS (nine men and one woman, aged 29-78 years) were included in the study. Six of the 10 received a gradient-guided subtotal (70%) or distal (50%) pancreatectomy. In the remaining four patients, diazoxide treatment was initiated and the precise mechanism of its action was assessed by meal tests. All of the patients showed a combination of postprandial neuroglycopaenia, negative prolonged fasts (except one patient) and negative localization studies for insulinoma, but positive calcium stimulation tests and nesidioblastosis in the gradient-guided resected pancreas. Immunohistological studies of the resected pancreatic tissues revealed neither an increased rate of proliferation of beta-cells nor an abnormal synthesis and/or processing of either proinsulin or amylin. Evidence of overexpression of the two pancreatic differentiation factors, PDX-1 and Nkx-6.1, as well as the calcium sensing receptor (CaSR) was absent. Nevertheless, abnormal expression of islet neogenesis-associated protein (INGAP), a human cytokine expressed only in the presence of islet neogenesis, in ducts and/or islets, was identified in three of the five patients studied. All of the six patients who received a surgical operation were relieved of further neuroglycopaenic attacks, but one patient who received a subtotal pancreatectomy developed diabetes. In the remaining four patients who received diazoxide treatment, hypoglycaemic episodes were satisfactorily controlled with an attenuated response of beta-cell peptides to meal stimulation. Our results strengthen the existence of this unique clinical hypoglycaemic syndrome from beta-cell hyperfunction as well as the value of the selective arterial calcium stimulation test in its correct diagnosis and localization. The mechanisms underlying beta-cell hyperfunction and release of insulin to calcium, however, remain poorly characterized. Nevertheless, in a subset of patients with NIPHS, there exists some, as yet undefined, pancreatic humoral/paracrine factor(s) other than proinsulin, amylin, PDX-1, Nkx-6.1 and possibly glucagon-like peptide-1 (GLP-1) that are capable of inducing the INGAP gene and, if activated, will initiate ductal proliferation and islet neogenesis. As for the treatment, we recommend that diazoxide be tried first in each patient and, should it fail, a gradient-guided subtotal or distal pancreatectomy be attempted.
    Clinical Endocrinology 12/2006; 65(5):566-78. DOI:10.1111/j.1365-2265.2006.02629.x · 3.46 Impact Factor
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    Wen-Ya Ma · Justin G.S. Won · Kam-Tsun Tang · Hong-Da Lin
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    ABSTRACT: Insulin autoimmune syndrome, characterized by the presence of insulin-binding autoantibodies and fasting or late postprandial hypoglycemia, is a rare cause of hypoglycemia. We report a patient with pulmonary tuberculosis who developed recurrent spontaneously post-absorptive hyperinsulinemic hypoglycemia after treatment with anti-tuberculous drugs. Imaging studies of the pancreas were unremarkable, and selective intra-arterial calcium stimulation with hepatic venous sampling for insulin failed to show a gradient, thus almost completely excluding the possibility of occult insulinoma or nesidioblastosis. Examinations of sera, however, disclosed a high titer of polyclonal insulin-binding autoantibodies containing at least 2 classes of binding sites, 1 with high affinity but low capacity, and the other with low affinity but high capacity. An oral glucose tolerance test revealed high serum levels of total insulin associated with relatively low levels of free insulin, but not of C-peptide, suggesting binding of the released insulin to autoantibodies. Regretfully, shortly after the withdrawal of isoniazid, the patient died of respiratory failure unrelated to hypoglycemia, and whether these antibodies were induced by isoniazid remains unknown. We recommend that insulin autoimmune syndrome be one of the differential diagnoses in patients with hyperinsulinemic hypoglycemia.
    Journal of the Chinese Medical Association 03/2005; 68(2):82-6. DOI:10.1016/S1726-4901(09)70140-6 · 0.85 Impact Factor
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    ABSTRACT: The selective intra-arterial calcium stimulation test has greatly facilitated the precise regionalization of insulinomas smaller than 2 cm, which noninvasive techniques (ultrasound [US], computed tomography [CT], magnetic resonance imaging [MRI]) often fail to localize. This study examined not only the role of the test in the localization of insulinomas, but also the responsiveness of 3 beta-cell peptides (insulin, C peptide, and proinsulin) and their relationship to the degree of differentiation of the tumor cells, using percentage decrease of both proinsulin/insulin (P/I) and proinsulin/C peptide (P/C) ratios after stimulation as indices. Ten consecutive surgically proven insulinoma patients each received an injection of calcium into the arteries supplying the pancreas after standard selective angiography and beta-cell peptide levels were measured in samples taken from the right hepatic vein before and 30, 60, 90, 120, and 180 seconds after each injection prior to operation. After surgery, the expressions of the calcium sensing receptor (CaSR) on the resected tumors were assessed by immunohistochemistry. Intra-arterial calcium stimulation with sampling either for insulin or for C peptide correctly predicted the site of insulinoma in 8 of 9 patients or in 7 of 8 patients if the 2 big malignant insulinomas were excluded; thus, the detection rate of this test was 89% and 88%, respectively. Calcium administration stimulated a marked and prompt release of insulin and C peptide simultaneously. Both peaked within 30 to 60 seconds, then declined gradually thereafter, remaining above the baseline at 180 seconds. The magnitude of increase correlated well with the corresponding percentage decrease of P/I and P/C ratios. The response of proinsulin was much less. Immunohistochemistry demonstrated variable membraneous staining for CaSR in normal pancreatic islets and in about 9% of the total normal beta cells, whereas staining in tumor cells was only minimally detectable. We conclude that selective intra-arterial calcium stimulation with hepatic venous sampling either for insulin or for C peptide is a highly sensitive method for the preoperative localization of small insulinomas. Calcium injection stimulates a brisk response of insulin, C peptide, and proinsulin simultaneously and the magnitude of increase of both insulin and C peptide appears to be correlated well with the degree of differentiation of the tumor cells. The exact mechanism by which calcium provokes the release of beta-cell peptides is less clear and whether the CaSR is involved in the mechanism of its action requires further study.
    Metabolism 11/2003; 52(10):1320-9. DOI:10.1016/S0026-0495(03)00200-2 · 3.89 Impact Factor
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    ABSTRACT: Adequate surgical treatment of hypoglycemia caused by benign diffuse islet cell disease (BDICD) is not associated with predictable results. Arterial stimulation and venous sampling (ASVS) has been reported to establish the diagnosis of BDICD, as well as serve as a guide to resection. The purpose of this study is to determine the efficacy of this method for the treatment of benign diffuse islet cell disease. We retrospectively reviewed 38 adults with symptomatic hyperinsulinemic hypoglycemia treated by a single surgeon from 1982 to 1998. Nine of them had pathologic evidence of BDICD. We demonstrated the clinical presentations, serum level of fasting blood sugar, insulin and C-peptide before and after operations, pathological results, and outcomes of distal pancreatectomy in 5 patients and ASVS-guided pancreatectomies in 4 patients with BDICD. Five patients (4 females and 1 male) who received distal pancreatectomy (Group 1) were aged from 19 to 75, and were culled from a group of 30 patients with spontaneous hyperinsulinemic hypoglycemia. Two had the multiple endocrine neoplasia (MEN) 1 syndrome. The follow-up was from 7 to 16 years. Three patients (including 1 MEN 1 patient) became diabetic. Another 1 is euglycemic, and the other MEN 1 patient developed recurrent disease. Four patients (2 males and 2 females, Group 2), found in a group of 8 patients with hyperinsulinemic hypoglycemia, had ASVS-guided pancreatectomies. Their ages ranged from 29 to 69 years. The area of the pancreas supplied by the splenic artery was removed in all patients. Follow-up from half to 2 years showed that all the patients had normal fasting levels of glucose, normal levels of insulin and C-peptide, and no more hypoglycemic attacks. Arterial stimulation venous sampling is a useful guide for pancreatectomy to treat adult patients with BDICD. Data from this small sample of patients suggest that the results may be superior to those obtained by "blind" distal pancreatectomy.
    Zhonghua yi xue za zhi = Chinese medical journal; Free China ed 04/2002; 65(3):111-8.
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    V S Fang · C C Juan · Y P Hsu · J.G.S. Won · L T Ho
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    ABSTRACT: The effect of vasoactive intestinal peptide (VIP) on cortisol production was studied in a primary culture enriched with guinea pig Zona Fasciculata (ZF) cells. In ZF cells, VIP stimulates cortisol secretion and enhances the steroidogenic action of ACTH. Compared to ACTH on an equal molar basis, the cortisol-stimulatory effect of VIP is at least 10-fold less potent. As VIP exhibits a wide range of biological actions with widespread distribution in the body, the steroidogenic action of VIP on the adrenal glands is not tissue-specific. There are VIP receptors in ZF cells. With the aid of a VIP receptor antagonist, we found that ACTH and VIP mutually bind each other's receptors with an affinity-ranking order of ACTH > VIP receptor antagonist > VIP. VIP stimulates cortisol production most likely through the cyclic AMP (cAMP) signaling pathway. Both ACTH receptors and the VIP receptors bind VIP receptor antagonist more avidly than VIP, but the bindings do not lead to a consequential effect on cAMP production and cortisol secretion. However, the VIP receptor antagonist counteracted ACTH and VIP to lower both cAMP and cortisol production. In addition, ASIF and BNP-32, which are the proven ACTH receptor antagonists, reduced the cortisol-stimulatory effect of ACTH and VIP. These results suggest that besides ACTH, VIP be an important factor in regulating the cortisol secretion from the adrenal cortex at the site of ACTH receptors. In cases with hypercortisolemia being detected concomitantly with normal or low ACTH levels, we may need to investigate the influential role of VIP.
    The Chinese journal of physiology 06/2001; 44(2):73-9. · 1.16 Impact Factor
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    V S Fang · C C Juan · J.G.S. Won · L T Ho
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    ABSTRACT: The suppressive effect of aldosterone secretion-inhibitory factor (ASIF) and brain natriuretic peptide (BNP-32) on the basal and ACTH-stimulated cortisol production in a primary culture enriched with guinea pig Zona Fasciculata (ZF) cells was further studied. The binding of 125I-labeled ACTH(1-24) and ASIF to ZF cells was found to be displaced by ACTH(1-24), [Phe2, Nle4 and Ala24]-ACTH(1-24), ASIF, and BNP in a concentration-dependent manner. The binding of 125I-labeled [Phe2, Nle4 and Ala24]-ACTH(1-24) to two transformed clones of mammalian cells expressing the guinea pig ACTH receptor was also competitively inhibited by ASIF and BNP. ASIF and BNP significantly suppressed ACTH-stimulated cAMP production in ZF cells. The 10- and 30-min cellular changes in cAMP induced by ASIF and BNP did not correlate in the rank order with the ultimate magnitude of cortisol suppression observed in ZF cells after a 24-hour treatment with these peptides. Nevertheless, the results did conform to the signaling mechanism of their action. Overall, the findings clearly demonstrated that ASIF and BNP suppressed the adrenocortical function and inhibited ACTH for their antagonistic action against ACTH primarily at the ACTH receptor site. These results support the notion that a physiological role of adrenal medulla in regulating the adrenocortical function may be mediated by the neuropeptides through a paracrine pathway.
    The Chinese journal of physiology 01/2001; 43(4):141-7. · 1.16 Impact Factor
  • S Y Lin · T Kao · J.G.-S. Won · K T Tang · H D Lin
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    ABSTRACT: Hürthle cell neoplasm of the thyroid gland is rarely associated with tumor necrosis. We report a case of Hürthle cell carcinoma of the thyroid gland with extensive necrosis. An 82-year-old man had had a right neck mass for more than 10 years. Approximately two to three weeks before he was hospitalized, this neck mass became progressively enlarged. An 131I scan could not demonstrate the right lobe of the thyroid gland, while the contralateral lobe was unremarkable. A 99mTc-sestamibi scan showed increased uptake on the lesion side. Fine needle aspiration cytology showed necrosis with macrophages in the initial aspirate, and the secondary aspirate appeared suspicious for a Hürthle cell tumor. The patient had a total thyroidectomy, and the pathology proved to be Hürthle cell carcinoma with tumor necrosis.
    Zhonghua yi xue za zhi = Chinese medical journal; Free China ed 03/1999; 62(2):111-5.
  • S Y Lin · C L Chang · T S Jap · H D Lin · J.G.-S. Won
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    ABSTRACT: Genitourinary tuberculosis (TB) rarely involves the adrenal gland. A 67-year-old man presented with progressively hyperpigmented skin and an enlarged mass over both testes. Early morning plasma cortisol concentration was low and adrenocorticotropic hormone (ACTH) concentration was high. A rapid ACTH stimulation test revealed the absence of plasma cortisol response and confirmed a diagnosis of primary adrenocortical insufficiency. An abdomen computed tomography (CT) scan disclosed enlargement of the right adrenal gland and punctuate calcification over the left one. This is compatible with tuberculous adrenalitis. Currettage biopsy of the prostate demonstrated chronic granulomatous inflammation with Langerhan's giant cells, but without TB bacilli. Anti-TB treatment, in addition to glucocorticoid and mineralocorticoid replacement, was administered. The testicular mass decreased progressively though the results of a subsequent ACTH stimulation test, six months later, disclosed no significant change. A follow-up CT scan, one and a half years later, showed a decrease in the size of the right adrenal mass.
    Zhonghua yi xue za zhi = Chinese medical journal; Free China ed 04/1998; 61(3):170-4.
  • W L Lee · J.G.S. Won · J H Chiang · J I Hwang · C H Lee · S H Tsay
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    ABSTRACT: A 69-year-old man with recurrent hypoglycaemia had inappropriately elevated plasma insulin level during a symptomatic hypoglycaemia, but had a negative prolonged fast. Computerized tomography (CT) of the abdomen revealed a nodular lesion over the body of pancreas, whereas pancreatic arteriography failed to show tumour blush. Hence, arterial stimulation (with calcium) and venous sampling (ASVS) was performed and a brisk response of plasma insulin level was found when calcium was injected both into the splenic and the superior mesenteric arteries. Since no tumour was found during the operation, the patient received subtotal distal pancreatectomy. Pathological examination of the resected tissue disclosed a typical finding of nesidioblastosis. We suggest that selective intra-arterial calcium injection with hepatic venous sampling for insulin gradients is useful for the diagnosis of adult nesidioblastosis.
    Diabetic Medicine 11/1997; 14(11):985-8. DOI:10.1002/(SICI)1096-9136(199711)14:11<985::AID-DIA483>3.0.CO;2-L · 3.12 Impact Factor
  • J. G. S. Won · D N Orth
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    ABSTRACT: Intracellular Ca2+ (Cai2+) stores contribute significantly to Ca2+ signaling in many types of cells. We studied the role of inositol trisphosphate (InsP3)-sensitive Ca2+ stores, a principal Cai2+ store that presumably is within the endoplasmic reticulum (ER), in cell signaling by examining the effect of thapsigargin (Tg), an ER Ca2+ pump inhibitor that depletes the ER Ca2+ pool, on ACTH secretion. Preincubation for 6-24 h with 2-20 nM Tg had no effect on the resting cytosolic free Ca2+ concentrations ([Cai2+]) but inhibited the ionomycin-stimulated spike-type increase in [Cai2+], which is mediated by InsP3-independent Cai2+ release from the ER, in a dose-dependent (IC50, 4 nM) and time-dependent manner. In ER Cai(2+)-depleted cells, the spike phase (initial 5 min) of the ACTH secretory response to arginine vasopressin (AVP), which is mediated by InsP3-induced Cai2+ release, was also attenuated (IC50, 7.3 nM). However, the spike phase of the ACTH secretory response to AVP was inhibited to a much greater degree than the spike-type response to ionomycin, suggesting that ER Cai2+ stores might have functions other than simply providing Ca2+ for InsP3-stimulated Cai2+ release. Tg pretreatment (IC50, 12 nM) also markedly inhibited the sustained plateau (final 15-min) phase of the ACTH secretory response to AVP, which is mediated by diacylglycerol-induced activation of protein kinase C and subsequent influx of extracellular Ca2+ via L-type voltage-sensitive Ca2+ channels (VSCC), but had no effect on the sustained (full 20 min) response to dioctanoylglycerol that directly activates protein kinase C. Tg had no effect on specific cell binding of [125I]AVP or on specific cell binding of [3H]phorbol 12,13-dibutyrate (except at 20 nM Tg), an index of protein kinase C concentration, or on protein kinase C activity. AVP significantly stimulated inositol trisphosphate accumulation, but pretreatment with Tg completely abolished this effect of AVP, whereas [3H]myoinositol incorporation into membrane-associated inositol lipids and inositol phosphates was unaffected. Thus, Tg-induced depletion of ER Cai2+ stores inhibited both the spike and plateau phases of the ACTH secretory response to AVP, presumably by inhibiting phospholipase C activity and the resulting generation of InsP3 and diacylglycerol. Preincubation with Tg inhibited, in a dose-dependent (IC50, 13 nM) and time-dependent manner, the sustained ACTH secretory response to corticotropin-releasing hormone (CRH) that is mediated by cAMP-induced activation of protein kinase A and Cae2+ influx via L-type VSCC, and the sustained response to forskolin, which directly activates adenylate cyclase.(ABSTRACT TRUNCATED AT 400 WORDS)
    Endocrinology 03/1996; 136(12):5399-408. DOI:10.1210/endo.136.12.7588288 · 4.50 Impact Factor
  • J.G.S. Won · D N Orth
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    ABSTRACT: Arachidonic acid metabolites have been implicated in the regulation of ACTH secretion. To define further which eicosanoid(s) is primarily involved, we examined the effects of both inhibitors of the three arachidonate metabolic pathways (cyclooxygenase, lipoxygenase, and epoxygenase) and specific eicosanoid products on ACTH secretion by rat pituitary corticotrophs in a microperifusion system. CRF stimulates sustained ACTH release that is mediated by protein kinase-A-induced extracellular Ca2+ (Cae2+) influx via L-type voltage-sensitive calcium channels (VSCC). Arginine vasopressin (AVP) stimulates an initial spike phase of ACTH release that presumably is mediated by inositol 1,4,5-trisphosphate-induced intracellular Ca2+ (Cai2+) release, followed by a sustained plateau phase of ACTH release that is mediated by protein kinase-C-induced Cae2+ influx via L-type VSCC. Pretreatment for 15 min with the lipoxygenase inhibitor nordihydroguaiaretic acid (NDGA; 50 microM), but not the cyclooxygenase inhibitor indomethacin (10 microM) or the epoxygenase inhibitor SKF525A (100 microM) inhibited the sustained response to CRF by 48% and the initial spike response to AVP by 38%. NDGA-induced inhibition was not reversed by indomethacin or SKF525A, alone or in combination, precluding arachidonate shunting into other pathways. However, the results suggested that epoxygenase metabolites may have a minor stimulatory and cyclooxygenase metabolites may have a minor inhibitory effect on ACTH secretion. Preexposure to NDGA suppressed by 43% the sustained response to 8-bromo-cAMP, which directly activates protein kinase-A; by 57% the sustained response to dioctanolglycerol, which directly activates protein kinase-C; and by 59% the spike-type response to ionomycin, which releases Cai2+ by an inositol 1,4,5-trisphosphate-independent mechanism. These results suggest that NDGA either inhibits the production of a lipoxygenase metabolite involved in Cae2+ influx and/or Cai2+ release or acts other than by inhibiting lipoxygenase, such as by directly blocking membrane transport of Cae2+. The three major lipoxygenase metabolites tested, 5(S)-, 12(S)-, and 15(S)-hydroxyeicosatetraenoic acid (HETE), all stimulated sustained ACTH release in a dose-dependent manner. At a concentration of 2 microM, 12(S)-HETE was 4.7 and 2.5 times more potent than 5(S)- and 15(S)-HETE, respectively, and completely reversed NDGA inhibition of both CRF- and AVP-stimulated ACTH secretion. The ACTH-releasing activity of 12(S)-HETE was inhibited 26% by removing Cae2+ and 54% by both removing Cae2+ and depleting Cai2+, indicating either that 12(S)-HETE facilitates transmembrane Ca2+ transfer or that increased cytosolic Ca2+ is necessary for 12(S)-HETE's action.(ABSTRACT TRUNCATED AT 400 WORDS)
    Endocrinology 11/1994; 135(4):1496-503. DOI:10.1210/en.135.4.1496 · 4.50 Impact Factor
  • J G Won · W E Nicholson · K N Ching · D N Orth
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    ABSTRACT: We studied the effect of Ca2+/phospholipid-dependent protein kinase-C (protein kinase-C) down-regulation by chronic exposure to phorbol 12-myristate 13-acetate (PMA) on ACTH secretion by dispersed male rat anterior pituitary cells in a microperifusion system. Preincubation for 24 h and preperifusion for 3 h with 0.1 and 1 microM PMA significantly inhibited (by 85% and 91%, respectively) the specific cell binding of [3H]phorbol 12,13-dibutyrate, an index of protein kinase-C concentration, and significantly reduced (by 101% and 20%, respectively) the sustained plateau (final 15-min) phase of the ACTH response to arginine vasopressin (AVP) and (by 56% and 54%, respectively) the sustained (full 20-min) response to dioctanoylglycerol (DOG), both of which are mediated by protein kinase-C activation. In contrast, the spike (initial 5-min) phase of the response to AVP, which is mediated by intracellular Ca2+ release from inositol 1,4,5-trisphosphate (InsP3)-sensitive stores, was significantly increased (by 112% and 99%, respectively), but the spike-type response to ionomycin, which releases intracellular Ca2+ by an InsP3-independent mechanism, was unaffected. AVP significantly stimulated inositol bisphosphate and InsP3, but not inositol monophosphate, accumulation, and PMA pretreatment significantly enhanced their AVP-stimulated accumulation (by 86%, 34%, and 78%, respectively), an effect that was abolished by simultaneous preperifusion with PMA and cycloheximide to inhibit new protein synthesis. Enhancement of the spike phase response to AVP and AVP-stimulated InsP3 accumulation were lost within 1 h of PMA removal, but [3H]phorbol 12,13-dibutyrate binding and the sustained responses to AVP and DOG remained suppressed after 3 h. Pretreatment with 0.1 and 1 microM PMA slightly reduced the sustained responses to CRF (by 29% and 16%, respectively) and 8-bromo-cAMP (by 8% and 12%, respectively), which are mediated by protein kinase-A activation and extracellular Ca2+ influx via L-type voltage-sensitive Ca2+ channels, but not the response to KCl, which is mediated by extracellular Ca2+ influx via all types of voltage-sensitive Ca2+ channels. The sustained response to CRF was still suppressed 1 h after PMA removal, but returned to the control level by 3 h. When new protein synthesis was inhibited by preperifusion with cycloheximide alone for 3 h after 24-h PMA pretreatment, recovery from the effects of PMA was abolished. Three-hour exposure to cycloheximide without PMA pretreatment inhibited the sustained responses to CRF, AVP, and DOG, but not the spite response to AVP.(ABSTRACT TRUNCATED AT 400 WORDS)
    Endocrinology 10/1993; 133(3):1274-83. DOI:10.1210/en.133.3.1274 · 4.50 Impact Factor
  • T S Jap · M S Hsieh · S F Jeng · J G Won · L T Ho · H Chiang
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    ABSTRACT: Succinyl cyclic AMP, coupled with human albumin, was injected into rabbit to elicit antibodies to the cyclic nucleotide hapten. The succinyl cyclic nucleotides were conjugated to human albumin through a carbodiimide coupling procedure. The radioligand was prepared essentially by the modified method of Hunter and Greenwood. The resulting radiolabeled 125-ScAMP-TME was subsequently purified by reverse phase chromatography on Seppak C18 cartridge and used as tracers. Free and bound form of labeled antigens in the assay system were separated according to their differences in adsorption to solid material, i.e., charcoal. The antisera in routine use had 8% cross-reactivity with cyclic GMP, but had no cross-reactivity with ADP, 5'-AMP or ATP. The sensitivity of the assay in standard was around 0.05 pmol/ml. The sequential saturation analysis system was superior to the equilibrium study in terms of its sensitivity in standard curve determination. The media dilution and recovery studies showed good parallelism with the standard curve. The intra-assay and inter-assay coefficient variations were 5% and 7%, respectively. It showed that a significant increase in tracer binding to the antibodies in equilibrium incubating system was obtained when they were incubated at 4 degrees C for up to 72 hours. When the standard curve was derived for Scatchard plot analysis, Kd of the curve decreased inversely with the increase of the antibodies diluted, the total binding capacity of the antibody would not alter. A thyroid-stimulating hormone produced a normal response of cyclic AMP concentrations in FRTL-5 tissue cultures.
    Zhonghua yi xue za zhi = Chinese medical journal; Free China ed 09/1992; 50(2):89-95.
  • T S Jap · C F Kwok · J G Won · L T Ho
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    ABSTRACT: In order to observe whether the improvement of diabetic control would promote insulin release of elder non-insulin-dependent diabetics, we performed oral glucose tolerance test and glucagon infusion in eight patients before and after fasting plasma glucose normalized with insulin therapy for three weeks. The levels of plasma glucose and C-peptide both on fasting and following intravenous glucagon infusion and oral glucose loading were measured. Their ages ranged from 60 to 72 years old. The initial fasting plasma glucose levels were 261 +/- 18 mg/dl (Mean +/- SEM). After insulin therapy for three weeks, the fasting plasma glucose levels dropped to 130 +/- 8 mg/dl (Mean +/- SEM, P less than 0.001). The fasting C-peptide/glucose ratio showed no difference before and after therapy. On the other hand, the C-peptidogenic index was markedly improved following insulin therapy, as compared with the value before therapy (P less than 0.05). These results suggested that greater C-peptide response was found in non-insulin dependent elderly diabetics following oral glucose after plasma glucose normalized with insulin therapy.
    Zhonghua yi xue za zhi = Chinese medical journal; Free China ed 06/1991; 47(5):320-4.
  • T S Jap · C F Kwok · L T Ho · J G Won · D M Ho
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    ABSTRACT: To examine the biochemical changes in coexisting hyperthyroidism and hyperparathyroidism, we have studied two female cases in our medical center. Both patients received biochemistry study, thyroid function test, thyroid autoantibody determination, parathyroid function tests and thyroid scan. They all had increased thyroid function. The concentration of parathyroid hormone was found to elevate in both cases. After thyroid function turned normal, hypercalcemia was still present. Both patients underwent neck operation. Parathyroid adenoma was found in both cases. The pictures of thyroid pathology showed diffuse hyperplasia in one case and lymphocytic thyroiditis in the other case.
    Zhonghua yi xue za zhi = Chinese medical journal; Free China ed 10/1990; 46(3):177-80.

Publication Stats

187 Citations
47.34 Total Impact Points


  • 1997–2015
    • National Yang Ming University
      • • Faculty of Medicine
      • • Institute of Clinical Medicine
      • • School of Medicine
      T’ai-pei, Taipei, Taiwan
  • 1986–2008
    • Taipei Veterans General Hospital
      • • Metabolism & Endocrinology Division
      • • Department of Medicine
      T’ai-pei, Taipei, Taiwan
  • 1993–1996
    • Vanderbilt University
      • Department of Medicine
      Нашвилл, Michigan, United States