Development of validated sandwich ELISA for detecting peanut allergen Ara h 3 in food

Peanut is an important food that can cause food allergies, often leading to moderate and severe allergic symptoms such as skin rashes, asthma, and even anaphylactic shock.Research indicates that Ara h 3 is one of the major peanut allergen. In order to establish a simple analytical method for detecting Ara h 3, we developed a sandwich enzyme-linked immunosorbent assay (ELISA) with antibodies that were induced from purified Ara h 3. The experimental results showed that the purified Ara h 3 had good purity, and we successfully prepared capture and detection antibodies. The method established in this study exhibited high specificity and did not cross-react with soybeans, cashew nuts, and sesame. For validation, including precision, recovery and sensitivity were in good condition. We also detected the Ara h 3 in peanut related foods. Overall, the ELISA developed in this study is a reliable method for Ara h 3 detection.

Selenium Lessens Osteoarthritis by Protecting Articular Chondrocytes from Oxidative Damage through Nrf2 and NF-κB Pathways

Osteoarthritis (OA) causes joint pain and disability due to the abnormal production of inflammatory cytokines and reactive oxygen species (ROS) in chondrocytes, leading to cell death and cartilage matrix destruction. Selenium (Se) intake can protect cells against oxidative damage. It is still unknown whether Se supplementation is beneficial for OA. This study investigated the effects of Se on sodium iodoacetate (MIA)-imitated OA progress in human chondrocyte cell line (SW1353 cells) and rats. The results showed that 0.3 μM of Se treatment could protect SW1353 cells from MIA-induced damage by the Nrf2 pathway by promoting the gene expression of glutathione-synthesis-related enzymes such as the glutamate-cysteine ligase catalytic subunit, the glutamate-cysteine ligase modifier subunit, and glutathione synthetase. In addition, glutathione, superoxide dismutase, glutathione peroxidase, and glutathione reductase expressions are also elevated to eliminate excessive ROS production. Moreover, Se could downregulate NF-κB, leading to a decrease in cytokines, matrix proteases, and glycosaminoglycans. In the rats, MIA-induced cartilage loss was lessened after 2 weeks of Se supplementation by oral gavage; meanwhile, glutathione synthesis was increased, and the expressions of pro-inflammatory cytokines were decreased. These results suggest that Se intake is beneficial for OA due to its effects of decreasing cartilage loss by enhancing antioxidant capacity and reducing inflammation.

S-Equol Protects Chondrocytes against Sodium Nitroprusside-Caused Matrix Loss and Apoptosis through Activating PI3K/Akt Pathway

Osteoarthritis (OA) is a common chronic disease with increasing prevalence in societies with more aging populations, therefore, it is causing more concern. S-Equol, a kind of isoflavones, was reported to be bioavailable and beneficial to humans in many aspects, such as improving menopausal symptoms, osteoporosis and prevention of cardiovascular disease. This study investigated the effects of S-Equol on OA progress in which rat primary chondrocytes were treated with sodium nitroprusside (SNP) to mimic OA progress with or without the co-addition of S-Equol for the evaluation of S-Equol's efficacy on OA. Results showed treatment of 0.8 mM SNP caused cell death, and increased oxidative stress (NO and H₂O₂), apoptosis, and proteoglycan loss. Furthermore, the expressions of MMPs of MMP-2, MMP-3, MMP-9, and MMP-13 and p53 were increased. The addition of 30 μM S-Equol could lessen those caused by SNP. Moreover, S-Equol activates the PI₃K/Akt pathway, which is an upstream regulation of p53 and NO production and is associated with apoptosis and matrix degradation. As a pretreatment of phosphoinositide ₃-kinases (PI₃K) inhibitor, all S-Equol protective functions against SNP decrease or disappear. In conclusion, through PI₃K/Akt activation, S-Equol can protect chondrocytes against SNP-induced matrix degradation and apoptosis, which are commonly found in OA, suggesting S-Equol is a potential for OA prevention.

Zinc Protects Articular Chondrocytes through Changes in Nrf2-Mediated Antioxidants, Cytokines and Matrix Metalloproteinases

Osteoarthritis (OA) is an age-related degenerative joint disease characterized by high oxidative stress, chondrocyte death and cartilage damage. Zinc has been implicated in the antioxidant capacity of the cell, and its deficiency might inhibit chondrocyte proliferation. The present study examined the potential of zinc as a preventive supplement against OA using the in vitro chondrosarcoma cell line SW1353 and an in vivo Wistar rat model to mimic OA progress induced by monosodium iodoacetate (MIA). The results demonstrated that, in SW1353 cells, 5 μM MIA exposure increased oxidative stress and decreased the expression of GPx1 and Mn-SOD but still increased GSH levels and HO-1 expression and enhanced the expression of interleukin (IL)-10, IL-1β, and matrix metalloproteinase (MMP)-13. Zinc addition could block these changes. Besides, the expression of Nrf2 and phosphorylated (p)-Akt was dramatically increased, implicating the p-Akt/Nrf2 pathway in the effects of zinc on MIA-treated cells. A rat model achieved similar results as those of cell culture, and 1.6 mg/kg/day of zinc supplementation is sufficient to prevent OA progress, while 8.0 mg/kg/day of zinc supplementation does not have a better effect. These findings indicate that zinc supplementation exerts a preventive effect with respect to MIA-induced OA progress.

Arecoline Increases Glycolysis and Modulates pH Regulator Expression in HA22T/VGH Hepatoma Cells, Leading to Increase of Intracellular Ca2+, Reactive Oxygen Species, and Anoikis

Background: Cancer cells proliferate rapidly and are resistant to cell death, relying on aggravated glycolysis to satisfy their increased demand for energy and biosynthetic precursors. However, this process may create unfavorable microenvironments, such as increased acidity, leading to cytotoxicity. Our previous study demonstrated that arecoline induces anoikis of HA22T/VGH hepatoma cells. The present study aimed to examine if arecoline induced anoikis is related to the glycolytic pathway and explore the underlying mechanisms.

Methods: HA22T/VGH cells were treated with arecoline and changes in the glycolytic end products lactate and ATP, glycolytic-related gene expression, intracellular and extracellular pH, pH-regulating gene expression, reactive oxygen species (ROS) levels, intracellular Ca²⁺ concentration ([Ca²⁺]i) and mitochondrial membrane potential were examined, relative to untreated cells. Cell viability and morphology were also assessed.

Results: Arecoline increased lactate and ATP production through induction of glycolytic genes, including glucose transporter 3 (Glut3), hexokinase 1 (HK1), hexokinase 2 (HK2), and pyruvate kinase (PK). The intracellular pH was not changed, despite increased lactate levels, implying that intracellular H⁺ was exported out of the cells. mRNA expression of pH regulators including monocarboxylate transporter 1 and 4 (MCT 1 and 4), sodium bicarbonate cotransporter 1 (NBC1), carbonic anhydrases (CA) IX and XII and vacuolar ATPase (V-ATPase) were down-regulated. Na⁺/H⁺ exchanger 1 (NHE1) mRNA levels remained unchanged while Na⁺/Ca²⁺ exchanger (NCX) was up-regulated and eventually [Ca²⁺]i was increased. ROS generation was increased and mitochondrial membrane potential was decreased followed by cell detachment and death. Addition of 2-deoxy-d-glucose, a glucose competitor that interferes with glycolysis, attenuated arecoline induction of lactate [Ca²⁺]i, ROS and cell detachment. Similarly, ROS scavengers could block the effects of arecoline.

Conclusions: This study demonstrated that arecoline induced glycolysis and modulated the mRNA expression of pH-regulator genes in HA22T/VGH cells. This phenomenon led to the elevation of [Ca²⁺]i, ROS generation, and subsequent cell detachment.

Osteoblasts survive the arsenic trioxide treatment by activation of ATM-mediated pathway

Arsenic trioxide (ATO) is widely used in tumor treatment, but excessive arsenic exposure can have adverse effects. We recently found that, in primary osteoblasts, ATO produces oxidative stress and causes DNA tailing, but does not induce apoptosis. We further examined the signaling pathway by which osteoblasts survive ATO treatment, and found that they were arrested at G2/M phase of the cell cycle at 30h and overrode the G2/M boundary at 48h. After treatment for 30h, there was increased Cdc2 phosphorylation and expression of Wee1, a Cdc2 kinase, and expression of the cell cycle inhibitor, p21(waf1/cip1), which interacts with Cdc2. Furthermore, levels of the phosphatase Cdc25C, which activates Cdc2, were decreased, while the ratio of its phosphorylated/inactivated form to the total amount was increased. Moreover, phosphorylation/activation of the checkpoint kinases Chk1, Chk2 and p53 levels were increased, as were levels of activated ATM and γ-H2AX. The cell viability was decreased as an ATM inhibitor was added. Additionally, these effects of ATO on γ-H2AX, Chk1, Chk2, p53, and p21(waf1/cip1) were reduced by an ATM inhibitor. These findings suggest that G2/M phase arrest of osteoblasts is mediated by Chk1/Chk2 activation via an ATM-dependent pathway by which osteoblasts survive.

Combined effect of soy isoflavones and vitamin D3 on bone loss in ovariectomized rats

OBJECTIVE

Several studies have shown that soy isoflavones have estrogen-like activities and might constitute an alternative to hormone replacement treatment. The present study investigated the effects of soy isoflavones alone and combined with vitamin D3 on prevention of bone loss.

METHODS

Sprague-Dawley rats were sham-operated (n = 8) or ovariectomized (OVX; n = 40), and then the OVX rats were randomly assigned to five groups that were untreated or treated for 14 wk with vitamin D3, 17β-estradiol, soy isoflavone extract (SIE), or vitamin D3 plus SIE. The effects of the isoflavones and 1α,25(OH)(2)D(3) on cultured osteoblasts and osteoclasts also were investigated.

RESULTS

In OVX rats, the bone mineral density and trabecular bone volume loss were improved by 17β-estradiol, SIE, or SIE plus vitamin D3 treatment. SIE treatment was more effective than vitamin D3 or 17β-estradiol in inhibiting increases in serum tumor necrosis factor-α levels and osteoblast osteoprotegerin expression. SIE plus vitamin D3 was more effective in increasing osterix expression than each alone. Bone cell cultures showed that the isoflavones induced preosteoblasts to differentiate into osteoblasts and increased osteoblast mineralization. Isoflavones inhibited preosteoclasts and osteoclast proliferation and decreased osteoclast resorption. The combination of isoflavones plus 1α,25(OH)(2)D(3) showed additive effects on the increase in cell proliferation of cultured preosteoblasts.

CONCLUSION

Treatment with soy isoflavones might be an alternative to hormone replacement therapy in decreasing bone loss from postmenopausal estrogen deficiency. In addition, there are further effects on increasing transcription factor osterix expression and preosteoblast proliferation when these were combined with vitamin D3.

Arsenic trioxide affects bone remodeling by effects on osteoblast differentiation and function

Arsenic trioxide (ATO) is widely used in tumor treatment, but excessive arsenic exposure can have adverse health effects. This study was to examine the association between ATO treatment and bone remodeling. The effects of ATO on osteoblast function were investigated in primary cell cultures and in an in vivo study in rats. Sprague-Dawley rats (n=30) were randomly assigned to 3 groups which were injected intraperitoneally with saline or 5 or 10 mg/kg of ATO for 4 weeks. In cell culture, ATO decreased osteoblast mineralization by decreasing alkaline phosphatase (ALP) expression and this effect was prevented by co-addition of inorganic phosphate (Pi). Moreover, levels of mRNAs for the transcription factors runt-related transcription factor 2 (Runx2) and osterix, the osteoblast osteogenic gene osteocalcin, and the adherence molecule vascular cell adhesion molecule-1 (VCAM-1) were decreased by ATO. Levels of mRNAs for the cytokine IL-6 were also decreased, whereas GM-CSF mRNA levels were increased. Similar effects of ATO on osteoblasts were seen in in vivo experiments in the rat. Moreover, decreases of bone turnover markers of osteocalcin, Procollagen type I N-terminal propeptide (PINP), and C-terminal cross-linked telopeptide (CTX) as well as bone mineral density (BMD) and trabecular bone volume of femur were observed in ATO-treated rats. These results suggest that ATO interferes with bone remodeling mostly through changes in osteoblast differentiation and function.

Hemeoxygenase-1 expression in response to arecoline-induced oxidative stress in human umbilical vein endothelial cells

BACKGROUND

Arecoline, the most abundant areca alkaloid, has been reported to stimulate reactive oxygen species (ROS) production in several cell types. Overproduction of ROS has been implicated in atherogenesis. Hemeoxygenase-1 (HO-1) has cytoprotective activities in vascular tissues. This study investigated the effect of arecoline on adhesion molecule expression and explored the role of HO-1 in this process.

METHODS

Human umbilical vein endothelial cells (HUVECs) were treated with arecoline, then ROS levels and the expression of adhesion molecules and HO-1 were analyzed and potential signaling pathways investigated.

RESULTS

After 2h of arecoline treatment, ROS production was stimulated and reached a maximum at 12h. Expression of the adhesion molecules ICAM and VCAM was also induced. Glutathione pretreatment completely blocked arecoline-stimulated ROS production and VCAM expression, but not ICAM expression. Arecoline also induced HO-1 expression and this effect was partly due by ROS stimulation. Inhibition of c-jun N-terminal kinase (JNK) by SP600125, p38 by SB 203580, or tyrosine kinase by genistein reduced arecoline-induced HO-1 expression. In contrast, inhibition of ERK (extracellular signal-related MAP kinase) by PD98059 had no effect. Transfection of HUVECs with the GFP/HO-1 gene, which resulted in a 5-fold increase in HO-1 activity, markedly, but not completely, inhibited the decrease in cell viability caused by arecoline.

CONCLUSIONS

This study demonstrates that, in HUVECs, arecoline stimulates ROS production and ICAM and VCAM expression. HO-1 expression is also upregulated through the ROS, tyrosine kinase, and MAPK (JNK and p38) signaling pathways.

Bilateral aldosterone-producing adenomas: differentiation from bilateral adrenal hyperplasia

BACKGROUND

Primary aldosteronism (PA) is a common curable disease of secondary hypertension. Most such patients have either idiopathic bilateral adrenal hyperplasia (BAH) or unilateral aldosterone-producing adenoma (APA). Bilateral APAs are reportedly extremely rare.

AIM

To compare the distinctive characteristics, clinical course, and outcomes of bilateral APA vs. BAH.

DESIGN

Retrospective record review.

METHODS

From July 1994 to Jan 2007, 190 patients diagnosed with PA underwent surgical intervention at our hospital. Bilateral APA was diagnosed in 7/164 patients with histologically-proven APA. Twenty-one patients diagnosed as BAH, and 21 randomly selected of unilateral APA patients, matched by age and sex served as controls.

RESULTS

Patients with bilateral APA had similar blood pressure, arterial blood gas analysis, spot urinary potassium to creatinine ratio and clinical symptoms to those with BAH, but lower serum potassium levels (p = 0.027), lower plasma renin activity (p = 0.037), and higher plasma aldosterone concentrations (p = 0.029). Aldosterone-renin ratio (ARR) after administration of 50 mg captopril was higher in bilateral APA than in BAH patients (p = 0.023), but not different between unilateral APA and BAH (p = 0.218). A cut-off of ARR >100 ng/dl per ng/ml/h and plasma aldosterone >20 ng/dl after captopril significantly differentiated bilateral APA from BAH. Bilateral subtotal adrenalectomy normalized blood pressure and biochemistry in all patients with bilateral APA.

DISCUSSION

Bilateral APA, presenting simultaneously or sequentially, may not be a rare disease, accounting for 4.3% of APA in this sample. The clinical presentations of bilateral functional adenoma are not different from BAH, but patients with low serum potassium and ARR >100 after captopril should be carefully evaluated for bilateral adenoma.

Zinc at pharmacologic concentrations affects cytokine expression and induces apoptosis of human peripheral blood mononuclear cells

OBJECTIVE

The present study examined the effect of zinc at concentrations of the apoptotic signaling pathway and immune function of peripheral blood mononuclear cells (PBMCs).

METHODS

PBMCs from healthy subjects were treated in vitro with various zinc concentrations to imitate different serum statuses of physiologic (2 to 15 microM) and pharmacologic (15 to 100 microM) concentrations to higher than 100 microM and analyzed their expressions of cytokines and apoptotically related factors.

RESULTS

Although a normal physiologic concentration of zinc had no effect on immunologic function or apoptosis of PBMCs, a pharmacologic concentration (100 microM) or higher affected both functions. Zinc decreased cell proliferation at concentrations higher than 100 microM and stimulated cytokine expression at concentrations of at least 100 microM. Further, at concentrations of at least 100 microM, apoptosis was induced, and expressions of caspase-3 and proapoptotic genes, including Fas (FasL) and c-fos, which trigger apoptosis through receptor-mediated extrinsic and mitochondrion-mediated apoptotic pathways, respectively, were increased. At concentrations at least 300 microM, expressions of antiapoptotic factors nuclear factor-kappaB, Bcl-2, and Bcl-X(L) were markedly decreased.

CONCLUSIONS

Zinc stimulates cytokine expression and induces apoptosis of PBMCs from healthy subjects only at concentrations equal to or greater than the serum pharmacologic range. Receptor-mediated extrinsic and mitochondrial-mediated intrinsic pathways are involved in this zinc-induced apoptosis.

Serum soluble transferrin receptor reflects erythropoiesis but not iron availability in erythropoietin-treated chronic hemodialysis patients

BACKGROUND

The diagnosis of iron deficiency using the current commonly used tests is usually difficult in hemodialysis patients. Soluble transferrin receptor (sTfR) has caught the attention of physicians recently as regards its use as a parameter for the evaluation of iron status. This study was conducted in order to evaluate the correlation of serum soluble transferrin receptor (sTfR) concentration with hematological parameters and iron profiles, in the role of identifying iron deficiency among dialysis patients.

METHODS

Seventy-three patients having received chronic hemodialysis and stable maintenance recombinant human erythropoietin (rHuEPO) therapy were included. Iron, total iron-binding capacity, ferritin and sTfR were measured in the first week. Following this, these patients began to receive intravenous iron dextran (2 mg/kg/week) for 4 weeks. The hematocrit (Hct), hemoglobin (Hb) levels and reticulocyte counts were evaluated weekly. At the beginning of fifth week, the sTfR level was measured again. Patients were classified as belonging to one of the following groups: serum ferritin < 100 microg/L - absolute iron-deficient group; initial ferritin level > or = 100 microg/L with an increase in hemoglobin of greater than 1 g/dL at the end of the study occult iron deficiency group; others - non iron-deficient group.

RESULTS

Seventy-one patients completed the study. The concentration of sTfR was positively correlated with Hct, Hb and reticulocyte index at the beginning (r = 0.236, p = 0.047; r = 0.257, p = 0.04; r = 0.401, p < 0.01, respectively) and at the end of the study (r = 0.384, p < 0.01; r = 0.338, p < 0.01; r = 0.427, p < 0.001, respectively). After 4 weeks of iron and rHuEPO therapy, the sTfR concentration increased, rather than declined, from 21.85 +/- 8.06 nM to 23.76 +/- 7.42 nM (p = 0.04) and the change was positively correlated with the changes in Hct, Hb and reticulocyte index. The administered rHuEPO doses did not differbetween the iron deficiency group (absolute deficiency, n = 3; occult deficiency, n = 10) and non-iron deficiency group (n = 58). The sTfR levels failed to identify the occult iron deficiency group because there was no difference between occult iron-deficient and non-iron-deficient patients (24.73 +/- 9.09 nM versus 21.60 +/- 7.89 nM, p = 0.34). Instead, transferrin saturation (TS) could be a differential marker between the 2 groups (19.0 +/- 10.9% versus 30.1 +/- 12.7%, p = 0.012).

CONCLUSION

The serum sTfR concentration is indeed an appropriate marker for erythropoiesis. The erythropoitic effect of administered rHuEPO could mask the effect of iron status on the sTfR concentration. This might make the sTfR concentration no longer an appropriate index to identify the presence of occult iron deficiency. Thus, TS and ferritin currently remain better methods for the evaluation of iron status in rHuEPO-treated chronic hemodialysis patients.

Dipyridamole inhibits TGF-beta-induced collagen gene expression in human peritoneal mesothelial cells

BACKGROUND

Peritoneal matrix accumulation is characteristic of peritoneal fibrosis (PF). Continuous ambulatory peritoneal dialysis (CAPD) patients who had persistent transforming growth factor-beta (TGF-beta) in their drained effluent had an increased risk of PF. We previously reported that TGF-beta stimulates the expression of types I and III collagen mRNA in cultured human peritoneal mesangial cells (HPMCs), which may predispose them to develop PF. Pharmacological interventions to attenuate TGF-beta-stimulated matrix accumulation in HPMC may have therapeutic potential for the treatment of PF. The SMAD family and the extracellular signal-regulated protein kinase (ERK1/2, p44/p42) pathways have been shown to participate in TGF-beta signaling. Our current study identified these signal pathways in HPMCs and investigated the molecular mechanisms involved in the inhibitory effects of dipyridamole on TGF-beta-induced collagen gene expression in HPMCs.

METHODS

HPMCs were cultured from human omentum by an enzyme digestion

METHOD

Expression of collagen alpha1(I) mRNA was determined by Northern blotting. The SMAD proteins and the ERK1/2 activity were determined by Western blotting.

RESULTS

TGF-beta-stimulated collagen alpha1(I) mRNA expression of HPMC was inhibited by dipyridamole in a dose-dependent manner. Smad2 and ERK1/2 were activated in response to TGF-beta; however, TGF-beta had little effect on the protein expression of Smad4. The addition of PD98059, which blocked activation of ERK1/2, suppressed TGF-beta-induced collagen alpha1(I) mRNA expression in a dose-dependent manner. At a concentration that inhibited collagen gene expression (17 microg/mL), dipyridamole suppressed ERK1/2 activation by TGF-beta. In contrast, the same concentration of dipyridamole had no effect on TGF-beta-induced activation of Smad2.

CONCLUSION

Dipyridamole inhibits TGF-beta-induced collagen gene expression in HPMC through modulation of the ERK pathway. Our study of dipyridamole may provide therapeutic basis for clinical applications in the prevention of PF.

High resistive index of the radial artery is related to early primary radiocephalic hemodialysis fistula failure

Forty-nine patients who had received radiocephalic hemodialysis fistula construction were evaluated with duplex Doppler ultrasonography to characterize the Doppler indices of the feed radial arteries just proximal to the site of anastomosis. Forty-four patients had fistulas with good function, and 5 patients had fistulas with inadequate blood flow or thrombosis within 4 weeks after the operation. A preliminary study showed extensive variability in peak systolic velocity and end-diastolic velocity in the feed arteries. The resistive index dropped significantly 1 week after the operation and remained relatively constant over the following 5 weeks. In the success group, the mean resistive index measured 1 week after operation was 0.40+/-0.06. It was higher than that of the failure group (mean resistive index: 0.52+/-0.06). Among patients with well-functioning fistulas, diabetic patients had higher resistive indices than did non-diabetic patients (0.44+/-0.04 vs. 0.37+/-0.06). Our results suggest that a higher resistive index of the feed artery is closely related to early autogenous primary hemodialysis fistula failure.

Dipyridamole inhibits PDGF-stimulated human peritoneal mesothelial cell proliferation

BACKGROUND

It has been proposed that proliferation of human peritoneal mesothelial cells (HPMCs) accompanied by collagen synthesis may contribute to the development of peritoneal fibrosis (PF) in patients of long-term continuous ambulatory peritoneal dialysis (CAPD). However, the precise molecular mechanism regulating HPMC proliferation has never been reported. Dipyridamole has been reported to have potential as an antiproliferative and antifibrotic agent. We investigated the mechanism and effect of dipyridamole in regulation of HPMC proliferation.

METHODS

HPMCs were cultured from human omentum by an enzyme digestion

METHOD

Cell proliferation was measured by the methyltetrazolium assay and intracellular cAMP was measured using an enzyme immunoassay kit. Cell-cycle distribution of HPMC was analyzed by flow cytometry. Extracellular signal-regulated protein kinase (p44/p42 ERK) activity and expressions of cell-cycle proteins (cyclin D(1), CDK4, pRB and p27(Kip1)) were determined by Western blotting.

RESULTS

The addition of DP suppressed PDGF-stimulated HPMC proliferation by cell-cycle arrest at the G1 phase. The antimitogenic effect of dipyridamole was mediated through the cAMP pathway. PDGF (25 ng/mL) increased the ERK1/2 activity of HPMC within 15 minutes, which maximized at 30 minutes, and the pretreatment with dipyridamole (17 microg/mL) substantially reduced the ERK response to PDGF by approximately 78.5%. PDGF induced elevated protein levels of cyclin D(1), but the CDK4 protein level did not change. Dipyridamole and DBcAMP had no effect on the levels of cyclin D(1) and CDK4 in PDGF-stimulated HPMC. PDGF decreased p27(Kip1) and induced pRB phosphorylation of HPMC. In contrast, dipyridamole prevented PDGF-induced p27(Kip1) degradation and attenuated PDGF-stimulated pRB phosphorylation.

CONCLUSION

Dipyridamole appears to inhibit PDGF-stimulated HPMC proliferation through attenuated ERK activity, preservation of p27(Kip1), and decreased pRB phosphorylation. Thus, dipyridamole may have therapeutic efficacy to prevent or alleviate PF.

Preoperative diagnosis and localization of aldosterone-producing adenoma by adrenal venous sampling after administration of metoclopramide

BACKGROUND AND PURPOSE

Adrenal venous sampling is the most reliable test to distinguish aldosterone-producing adenoma (APA) from idiopathic hyperaldosteronism (IHA). The diagnostic accuracy can be improved by administration of adrenocorticotropin to minimize pulsatile secretion of aldosterone. Metoclopramide (MCP), a dopamine antagonist, can increase aldosterone secretion promptly without affecting cortisol secretion. This study investigated the diagnostic accuracy of adrenal venous sampling after MCP injection for the preoperative diagnosis and localization of APA.

METHODS

Prospective diagnosis and adrenalectomy was based on adrenal venous sampling in 23 patients with a diagnosis of primary aldosteronism. Plasma aldosterone concentrations from adrenal veins and the inferior vena cava were measured before and 30 minutes after intravenous administration of 10 mg MCP. The ratio of bilateral adrenal venous aldosterone concentrations after MCP was used for diagnosis as follows: a ratio greater than 5 indicated APA, less than 3 indicated IHA, and 3-5 indicated an intermediate diagnosis.

RESULTS

Catheterization of the right adrenal vein was unsuccessful in three patients. Twelve of 13 patients with an aldosterone ratio greater than 5 after MCP underwent unilateral adrenalectomy, and APA was confirmed in 11 of these patients. One patient with an intermediate diagnosis also had surgically confirmed APA. Six patients had a ratio less than 3. Before MCP administration, 10 of 13 patients with APA had a ratio greater than 5, and three patients had a ratio between 3 and 5; one patient with IHA had a ratio greater than 5. MCP improved the diagnosis of APA to an accuracy of 92% (12/13). Correct diagnosis of APA based on computerized tomography (CT) was 85% (11/13). There was discordance between the findings of adrenal venous sampling and CT in four of 20 patients.

CONCLUSIONS

Administration of MCP to stimulate aldosterone secretion during adrenal venous sampling can improve the accuracy of differential diagnosis between APA and IHA.

Dipyridamole inhibits human peritoneal mesothelial cell proliferation in vitro and attenuates rat peritoneal fibrosis in vivo

BACKGROUND

Peritoneal fibrosis (PF) is one of the most serious complications after long-term continuous ambulatory peritoneal dialysis (CAPD). Proliferation of human peritoneal mesothelial cells (HPMC) and matrix over-production are regarded as the main processes predisposing to PF. Dipyridamole (DP) has been reported to have potential as an antiproliferative and antifibrotic agent. We thus investigated the effect of DP in inhibiting proliferation and collagen synthesis of HPMC. A rat model of peritonitis-induced PF was also established to demonstrate the in vivo preventive effect of DP.

METHODS

HPMC was cultured from human omentum by an enzyme digestion

METHOD

Cell proliferation was measured by the methyltetrazolium assay. Intracellular cAMP was measured using an enzyme immunoassay (EIA) kit. Total collagen synthesis was measured by (3)H-proline incorporation assay. Expression of collagen alpha1 (I) and collagen alpha 1 (III) mRNAs was determined by Northern blotting. The rat model of peritonitis-induced PF was developed by adding dextran microbeads (Cytodex, 8 mg/1 mL volume) to a standardized suspension (3 x 10(9)) of Staphylococcus aureus. DP was administrated via intravenous infusion (4 mg in 1 h) daily for seven days. Macroscopic grading of intraperitoneal adhesions and histological analyses of peritoneal thickness and collagen expression were performed.

RESULTS

Addition of DP to HPMC cultures suppressed serum-stimulated cell proliferation and collagen synthesis. The antimitogenic and antifibrotic effects of DP appear to be predominantly mediated through the cAMP pathway, as DP increased intracellular cAMP in a dose-dependent manner. The macroscopic grade of intraperitoneal adhesion and peritoneal thickness were both significantly increased in animals treated with Cytodex plus S. aureus; on the other hand, DP attenuated these fibrotic changes with statistical significance (P < 0.01). Analysis of gene expression of collagen alpha 1 (I) and alpha1 (III) in the peritoneal tissue of experimental animals yielded similar results.

CONCLUSIONS

This study suggests that dipyridamole may have therapeutic potential in treating peritoneal fibrosis.

Incidence of exit-site infection with various exchange systems in continuous ambulatory peritoneal dialysis

BACKGROUND AND PURPOSE

The disconnect twin-bag (TB) system was first introduced in Taiwan for use as an exchange system in continuous ambulatory peritoneal dialysis (CAPD) in 1995. Following its introduction, the incidence of CAPD-associated peritonitis declined, but the incidence of exit-site infection (ESI) increased. To determine the cause of the increase in ESI incidence after the introduction of the TB system, this study compared the incidence of ESI among patients using the O set, ultraviolet antiseptic (UV) device, and the TB system.

METHODS

A total of 170 patients who had received CAPD for more than 3 months were enrolled in this study. Poisson test and Kaplan-Meier survival analysis were used to compare the ESI incidence and ESI-free catheter survival among patients using the O set, UV device, or TB system. Cox stepwise forward proportional hazard analysis was used to assess the impact of sex, education, cause of uremia, age, and type of exchange system on ESI.

RESULTS

The incidences of ESI differed significantly among patients using the three exchange systems, with 20.9, 13.8, and 4.0 episodes per 100 patient-years for patients using the TB system, O set, and UV device, respectively. New patients using the TB system also had a shorter mean interval of ESI-free catheter survival than those using the UV device (26.9 vs 58.8 months, p = 0.002). In the Cox stepwise forward proportional hazard analysis, non-lupus patients had a lower risk of developing ESI than lupus patients (relative risk [RR] 0.40, p = 0.03). The RR of ESI in patients using the UV device was also lower than in those using the TB system (RR 0.15, p < 0.01).

CONCLUSION

In this study, use of the TB system was associated with a higher incidence of ESI. The increased ESI incidence may be related to the heavier mini-transfer set of the TB system. Therefore, special attention should be given to fastening the mini-transfer set tightly during the exchanging procedure to prevent traction on the exit-site, which is associated with an increased incidence of subsequent ESI.

Clinical features of and risk factors for fungal peritonitis in peritoneal dialysis patients

BACKGROUND AND PURPOSE

Fungal peritonitis (FP) is a serious complication for peritoneal dialysis (PD) patients and can result in technical failure and mortality. Catheter removal remains the mainstay of treatment. This study sought to identify the risk factors for FP in order to facilitate the prevention of this catastrophic complication.

METHODS

A total of 246 patients who received long-term PD from 1985 to 1998 were included in this retrospective study. Twenty episodes of FP occurred in 19 patients. The clinical characteristics, pathogens, treatment modalities, and outcomes of the FP episodes were retrospectively reviewed. The FP incidence in various demographic and clinical groups, classified according to sex, age, education, and underlying cause of uremia, were compared with the Poisson test.

RESULTS

Thirteen episodes of FP were caused by yeast, and the remaining episodes were caused by Aspergillus spp. Age, sex, and education did not affect the FP incidence. Lupus patients (969 patient-months) had a higher incidence of FP than patients with other underlying diseases (p < 0.05). The 19 FP patients also had a higher incidence of bacterial peritonitis than other PD patients (p < 0.01). Among the 20 FP episodes, 14 (70%) were preceded by antibiotic use, and eight (40%) developed during hospitalization. Steroids were used at the time of FP in five of six lupus patients. Seven patients (37%) died within 1 month after diagnosis of FP. Five patients were able to remain on PD after FP, but only three patients were able to maintain catheter placement.

CONCLUSION

The risk factors for FP identified in this study include the use of antibiotics and steroids, underlying lupus, frequent occurrence of bacterial peritonitis, and hospitalization. Antifungal therapy may allow the catheter to be kept in place in a few patients, but catheter removal should be considered in patients whose FP is refractory to medical treatment.

Pentoxifylline inhibits human peritoneal mesothelial cell growth and collagen synthesis: effects on TGF-beta

BACKGROUND

Prevention or treatment of peritoneal fibrosing syndrome has become an important issue in patients on continuous ambulatory peritoneal dialysis (CAPD). Recent evidence has suggested that mesothelial stem cell proliferation and matrix over-production predispose the development of peritoneal fibrosis. We investigated whether pentoxifylline (PTX) affects human peritoneal mesothelial cell (HPMC) growth and collagen synthesis.

METHODS

HPMC was cultured from human omentum by an enzymic disaggregation method. Cell proliferation was assayed using a methyltetrazolium uptake method. Cell cycle analysis was performed by flow cytometry. Collagen synthesis was measured by 3H-proline incorporation into pepsin-resistant, salt-precipitated collagen. Prostaglandins and cAMP were determined by enzyme immunoassay. Northern blot analysis was used to determine mRNA expression.

RESULTS

Our data show that PTX inhibited serum-stimulated HPMC growth and collagen synthesis in a dose-dependent manner. Cell cycle analysis showed that PTX arrested the HPMCs in the G1 phase. PTX decreased the procollagen alpha1 (I) mRNA expression either stimulated by serum or transforming growth factor-beta (TGF-beta). PTX did not alter prostaglandins synthesis but dose-dependently increased intracellular cAMP level. PTX, the same as 3-isobutyl-l-methylxanthine, could potentiate prostaglandin E1 (PGE1) increased cAMP levels of HPMC. The antimitogenic and antifibrogenic effects of PTX on HPMC were reversed by N-[2]-((p-Bromocinnamyl)amino)ethyl]-5-isoquinolinesulfonamide (H-89). Therefore, the mechanism of these effects may be due to the phospodiesterase inhibitory property of PTX.

CONCLUSIONS

These data suggest that PTX may have a role in treating peritoneal fibrosing syndrome.

Endothelin-1 chronically inhibits Na/H exchanger-3 in ET(B)-overexpressing OKP cells

Endothelin-1 (ET-1) acutely increases Na/H antiporter activity in OKPET(B)6 cells, an opossum kidney proximal tubule cell line transfected with ET(B) receptor cDNA. The purpose of the present study was to examine the chronic effect of ET-1 on Na/H antiporter activity in OKP cells and to examine whether Na/H exchanger (NHE)-3 mRNA and protein abundance are regulated by ET-1. Quiescent OKPET(B)6 cells were treated with 10 nM ET-1 for 3, 6 or 24 h and Na/H antiporter activity was assayed. The Na/H antiporter activity in 3-h ET-1-treated cells was not different from controls. However, Na/H antiporter activity was significantly decreased by 29% at 6 h and 72% at 24 h. The effect of ET-1 on Na/H antiporter activity was blocked by BQ788, an ET(B) receptor antagonist, but not BQ123, an ET(A) receptor antagonist. The NHE-3 mRNA abundance in ET-1-treated cells was not different from controls at 3 h. However, there was a significant decrease in NHE-3 mRNA abundance at 6 and 24 h. There was also a significant decrease in NHE-3 protein abundance at 6 and 24 h. In summary, ET-1 chronically inhibits NHE-3 in OKPET(B)6 cells.

Idiopathic multicentric osteolysis with nephropathy

Idiopathic multicentric osteolysis is a rare syndrome that manifests with progressive loss of carpal and tarsal bones in childhood. Affected children have arthritic-like episodes, followed by progressive deformities, radiographic osteolytic changes, and variable degrees of disability. A rare form of this disease (type III, sporadic) is associated with serious nephropathy. We present the first reported case of type III idiopathic multicentric osteolysis in a Chinese woman. The patient, a 34-year-old woman with normal mental development and no family history of bone or kidney disease, presented with a 4-day history of nausea and vomiting. She had shortening and swelling of the hands, which had occurred in childhood and persisted at the time of admission. X-ray studies showed disappearance of the carpal bones, and multiple osseous erosions of the tarsal bones. Hypertension, severe azotemia, and metabolic acidosis were also noted. Advanced renal disease was documented after a series of investigations, including renal biopsy. She is now dialysis-dependent. This case illustrates the importance of early diagnosis and management of idiopathic multicentric osteolysis with nephropathy.

Differential expression of type 1 angiotensin II receptor mRNA and aldosterone responsiveness to angiotensin in aldosterone-producing adenoma

Aldosterone secretion in most patients with aldosterone-producing adenomas (APAs) is typically unresponsive to angiotensin II stimulation (AII-unresponsive, AII-U). In some patients, however, plasma aldosterone increases in response to AII stimulation (AII-responsive, AII-R). This differential aldosterone responsiveness could be related to the levels of type 1 AII receptors (AT1R) in the APA. To test this hypothesis, plasma aldosterone levels in response to upright posture and/or sequential high- and low-salt diets were measured by radioimmunoassay in nine patients with APAs. AT1R mRNA levels in the adenomas were quantified by competitive reverse transcription-polymerase chain reaction and correlated to the cellular composition of the adenoma. Two patients were categorised as AII-R by an increase of plasma aldosterone greater than 50% over the baseline. The remaining seven patients who had blunted plasma aldosterone responses were classified as AII-U. Histologically, the AII-R APAs consisted predominantly of zona glomerulosa (ZG)-like cells (> 90%), while the AII-U APAs contained zona fasciculata (ZF)-like cells ranging from 28 to 72%. There was an inverse relationship between the levels of AT1R mRNA in the APA and the percentage of ZF-like cells in the adenoma (n = 9, r = 0.73, P < 0.05). In situ hybridisation findings demonstrated that AT1R mRNA was more uniform and intensive in ZG-like cells than in ZF-like cells. These results suggest that heterogenous aldosterone responsiveness to angiotensin in APAs is histologically dependent and related to the differential expression of AT1R mRNA in the adenoma.

Pentoxifylline inhibits PDGF-induced proliferation of and TGF-beta-stimulated collagen synthesis by vascular smooth muscle cells

There is growing evidence that pentoxifylline (PTX) may have potential value as an antiproliferative and antifibrogenic agent. To assess whether this drug may be of use in the prevention of atherosclerosis or restenosis after angioplasty, we investigated the ability of PTX to inhibit proliferation and collagen synthesis in rat vascular smooth muscle cells (VSMCs) under both basal and platelet-derived growth factor (PDGF)- or transforming growth factor-beta (TGF-beta)- stimulated conditions. Intracellular cyclic AMP (cAMP) and cyclic GMP (cGMP) levels were measured in confluent cells using enzyme immunoassay kits. Cell proliferation was measured by methyltetrazolium assay. Cell cycle distribution was determined by flow cytometry. Total collagen synthesis was measured by 3H-proline incorporation assay. Expression of collagen alpha 1(I) and collagen alpha 1(III) mRNAs was detected by northern blotting. Addition of PTX to VSMC cultures suppressed both basal and PDGF-AB (25 ng/ml)-driven cell proliferation, in conjunction with a cell cycle blockade at the G1/S phase at 24 h. This effect was predominantly cAMP-dependent, as PTX increased cAMP in a dose-dependent manner (0.03 to 0.33 mg/ml) but not cGMP level, and the addition of dibutyryl-cAMP (0.2 to 2 m m) closely mimicked the effect of PTX. Furthermore, co-incubation with a selective inhibitor of cAMP-dependent protein kinase (PKA), H-89 (2.0 microm), or an N -myristoylated PKA pseudosubstrate nonapeptide, m-phi PKA (10 microm), prevented the antimitogenic effect of PTX. PTX also suppressed both basal and TGF- beta 1-augmented collagen alpha 1(I) and collagen alpha 1(III) mRNA levels beginning at 24 h, and attenuated both basal and TGF-beta 1 (5 ng/ml)-stimulated total collagen synthesis at 48 h. Co-incubation with H-89 or m-phi PKA reversed PTX-attenuated collagen alpha 1(I) and collagen alpha 1(III) mRNA levels at 24 h. These data suggest that the antimotigenic and anticollagen effects of PTX were mediated predominantly through a cAMP-PKA effector pathway. The dual effect of PTX on VSMC proliferation and collagen synthesis may form the rationale for animal or clinical trials for the treatment of vascular occlusion due to atherosclerosis and restenosis following angioplasty.

Urinary endothelin-1 in patients with renal disease

The purpose of this study was to investigate the usefulness of urinary endothelin-1 (ET-1) as a marker of renal disease. We measured urinary excretion of ET-1 in 28 patients with glomerulonephritis (GN), 22 patients with chronic renal failure (CRF), 40 patients with end-stage renal disease (ESRD), and 17 healthy volunteers. There was no significant difference in 24-hour urinary ET-1 excretion among the four groups (mean +/- SEM, 0.49 +/- 0.22 ng in controls, 0.79 +/- 0.37 ng in GN patients, 0.39 +/- 0.18 ng in CRF patients, and 0.28 +/- 0.11 ng in ESRD patients). The 24-hour urinary excretion of ET-1 in patients with GN or CRF showed significant correlation with the urinary excretion of sodium (r = 0.27, p < 0.05). The 24-hour urinary beta 2-microglobulin (beta 2M) excretion in patients with CRF (18.4 +/- 2.6 mg) or ESRD (9.7 +/- 1.1 mg) was significantly higher than in normal control subjects (0.23 +/- 0.11 mg). Serum creatinine concentration was positively correlated with the 24-hour urinary excretion of beta 2M in patients with GN or CRF (r = 0.50, p < 0.001). These findings indicate that urinary ET-1 is not as good a marker of renal disease as urinary beta 2M. However, it may be responsible for urinary sodium excretion in patients with GN or CRF.

Pharmacologic agents inhibit rat mesangial cell proliferation and collagen synthesis

Prevention of the development of end-stage renal disease is one of the most promising areas of research in nephrology. Because mesangial cell proliferation and extracellular matrix accumulation have been regarded as antecedents of glomerulosclerosis, agents that can inhibit mesangial cell proliferation may have a potential to retard the progression of renal diseases. Therefore, we investigated several clinically available agents that might affect mesangial cell proliferation and collagen synthesis in male Sprague-Dawley rats. Cell proliferation was measured by the tetrazolium dye uptake method. Collagen synthesis was measured by 3H-proline incorporation into pepsin-resistant, salt-precipitated collagen. Intracellular cAMP levels were measured by enzyme immunoassay. Our results showed that hydralazine (82% inhibition at 10 micrograms/mL), ticlopidine (61% inhibition at 30 micrograms/mL), aminophylline (66% inhibition at 200 micrograms/mL), and nicametate (91% inhibition at 1 mg/mL) inhibited serum-stimulated rat mesangial cell (RMC) growth in a dose-dependent manner. Ticlopidine (43% inhibition at 30 mg/mL), aminophylline (52% inhibition at 200 mg/mL), and nicametate (35% inhibition at 1 mg/mL) inhibited collagen synthesis in confluent RMCs. Aminophylline may act through increasing intracellular cAMP levels (9.7 +/- 0.7 pmol/mg protein at 200 micrograms/mL of aminophylline vs 4.2 +/- 0.6 pmol/mg protein at control). These data suggest that aminophylline, ticlopidine, hydralazine, and nicametate can inhibit RMC proliferation and collagen synthesis.

Integrated medical informatics with small group teaching in medical education

National Taiwan University College of Medicine (NTUCM) introduced small groups of teaching and basic-clinical integrated courses for medical students in 1992. By using computer network and multimedia techniques, this study tried to overcome barriers to learning in small group teaching. The Department of Medical Informatics of NTUCM established campus networking and computer classrooms and provided Internet and intranet network services including mail, netnews, bulletin board systems (BBS), world wide web (WWW), gopher, ftp and local file servers. To implement an interactive learning environment, the authors first tried mail lists, newsgroups and BBS. Next an integrated learning system prototype on the WWW was developed to provide functions including online syllabus, discussion boards simulated to BBS, online talk, interactive case studies, virtual classroom with video on demand (VOD) and Internet medical resources. The results showed that after the medical students completed the required course of medical informatics and had good network access using a network to communicate with each other became a daily practice. In the future, the system will extend to the tutoring of clinical practice and continuing medical education. The authors expect a national medical education network and more international cooperation and exchange.

Hydralazine inhibits human peritoneal mesothelial cell proliferation and collagen synthesis

The integrity of the mesothelial layer is essential for both defence and solute transport in continuous ambulatory peritoneal dialysis (CAPD). The human peritoneal mesothelial cell (HPMC) culture has been shown to be a very useful tool to study the peritoneal mesothelial stem cell behaviour. We investigated whether hydralazine, an antihypertensive agent frequently used, might affect HPMC growth and collagen synthesis. HPMCs were cultured from specimens of human omentum by enzymatic disaggregation of omentum. HPMC growth was evaluated by modified methyltetrazolium (MTT) assay. Cell viability was confirmed by trypan blue exclusion and lactate dehydrogenase assay. Collagen synthesis was measured by 3H-proline incorporation into pepsin-resistant, salt-precipitated collagen. Intracellular cAMP levels were measured by enzyme immunoassay. The procollagen alpha 1 (I) mRNA expression was evaluated by Northern blot analysis. Hydralazine inhibited serum-stimulated HPMC growth in a dose-dependent manner. The maximal inhibition was 93% at a concentration of 100 micrograms/ml. Hydralazine inhibited collagen synthesis in confluent mesothelial cells (47% inhibition at a concentration of 100 micrograms/ml). The procollagen alpha 1 (I) mRNA expression was also decreased by hydralazine (about 50% decrease at 100 micrograms/ml). These effects may be due to the phosphodiesterase inhibition property of hydralazine to increase intracellular cAMP levels. These data suggest that the use of hydralazine in CAPD patients may affect peritoneal membrane function and integrity.

Quantitative analysis of messenger ribonucleic acid encoding natriuretic peptide receptors in aldosterone-producing adenoma

There exist conflicting data regarding the inhibitory effect of atrial natriuretic peptide on aldosterone production from aldosterone-producing adenoma (APA). Natriuretic peptides mediate their actions through natriuretic peptide receptors (NPRs). Whether or not NPRs are present in the tumors remains controversial. To elucidate this paradox, gene expression of NPRs was examined by Northern blot analysis and competitive polymerase chain reaction in tumorous and non-tumorous portions of APA, and in normal adrenal gland from patients with renal cell carcinoma. The results of Northern blot analysis showed the presence of messenger ribonucleic acid (mRNA) of three NPRs in all adrenal tissues, including APA. The proportional expression of NPR gene transcripts in APA was type A (0.6%), type B (18.7%), and type C (80.7%). The levels, but not the proportions, of type C and possibly type B NPR mRNAs were lower in tumorous and non-tumorous portions of APA compared to those in normal adrenal gland (type C 190.2 +/- 24.5 [means +/- SEM, normal adrenal gland] > 168.1 +/- 20.8 [non-tumorous portion] > 112.2 +/- 15.5 [tumorous portion] pg/10 micrograms total RNA, F = 3.82, P < 0.05; type B 45.2 +/- 8.5 [normal adrenal gland] > 30.0 +/- 5.2 [non-tumorous portion] > 25.1 +/- 4.1 [tumorous portion] pg/10 micrograms total RNA, F = 3.03, P = 0.065). The mRNA levels of type C, rather than type A or type B, NPR were correlated with the percentage of zona fasciculata-like cells in APA (r = 0.90, P < 0.05). In conclusion we have demonstrated the presence of mRNA encoding the three NPRs in APA.(ABSTRACT TRUNCATED AT 250 WORDS)

Zona fasciculata-like cells determine the response of plasma aldosterone to metoclopramide and aldosterone synthase messenger ribonucleic acid level in aldosterone-producing adenoma

The different responses of plasma aldosterone to ACTH and angiotensin II in aldosterone-producing adenoma (APA) is thought to be due to the various cellular compositions of the tumors. To investigate whether the dopaminergic regulation of aldosterone in APA is also dependent on the cellular types, we studied the effects of metoclopramide on plasma aldosterone in six patients with APA. The messenger RNA (mRNA) levels of aldosterone synthase (P450aldo), 11 beta-hydroxylase (P450(11) beta), and 17 alpha-hydroxylase (P450(17) alpha) of APA and normal adrenal glands were determined by competitive polymerase chain reaction. After administration of metoclopramide (an antagonist of dopamine-2 receptor), the increment of plasma aldosterone correlated inversely with the percentage of zona fasciculata cells of APA. The mRNA level of P450aldo in the tumorous portion was much higher, whereas the levels of P450(11) beta and P450(17) alpha mRNAs were lower, than those of the nontumorous portion and normal adrenals. There was a correlation of the percentage of zona fasciculata cells in APA with the levels of P450aldo and P450(11) beta mRNAs, but not with P450(17) alpha mRNA. These results suggest that differential responsiveness of plasma aldosterone to metoclopramide may be due to various proportions of different cell types in APA that may have different expression of dopamine-2 receptor. In addition, this histologically dependent expression was present at the transcriptional level of the gene responsible for aldosterone biosynthesis.

Blood pressure, circulating atrial natriuretic peptide and sodium excretion responses during acute saline infusion in patients with essential hypertension

In order to examine whether changes in circulating atrial natriuretic peptide (ANP) and sodium excretion during saline infusion in patients with essential hypertension (EH) could be modulated by the severity of resting arterial blood pressure (BP), 30 subjects with EH and nine normotensive subjects were given 2 L of isotonic saline infusion at a rate of 500 mL/hour. Plasma ANP concentrations in EH increased significantly from 64.9 +/- 5.1 (mean +/- SEM) to 92.5 +/- 12.8 pg/mL at the first hour and peaked at the second hour. In normotensives, the increase of plasma ANP was not significant until the fourth hour of infusion. Hypertensive subjects sustained a greater percentage increment of mean BP (MBP) than normotensives at the end of infusion. Those with pre-saline MBP exceeding 107 mmHg (group A) exhibited a faster and greater rise in plasma ANP after saline loading than those having less than or equal to 107 mmHg (group B). The post-saline four-hour natriuresis was appreciably higher in group A than group B, while the percentage increment of MBP at the fourth hour was significantly greater in the latter as compared to normal controls. These results indicate that patients with higher basal arterial pressure attain a faster and greater ANP response following saline infusion than those with lower BP. This phenomenon may be responsible for the maintenance of short-term fluid-volume and BP homeostasis during acute sodium loading in established EH.

Correlation between renin responsiveness to furosemide and antihypertensive effect of captopril in patients with normal-renin essential hypertension

The relationship between renin responsiveness to furosemide and the antihypertensive effect of captopril in patients with normal-renin essential hypertension were studied in 23 patients including nine men (mean age, 41 years) and 14 women (mean age, 40 years). Those who had an increment of more than 50% in plasma renin activity (PRA) two hours after an intravenous injection of 20 mg furosemide were classified as group A (n = 13) and the others were classified as group B (n = 10). Baseline PRA, plasma aldosterone and mean blood pressure (MBP) were not different between the two groups. Both groups showed no significant difference in natriuresis following furosemide administration. Significant change in MBP was observed after an oral dose of 100 mg captopril within four hours in group A, but not in group B. These data suggest that renin responsiveness to a single intravenous dose of furosemide can be a useful test for predicting the therapeutic response to captopril in patients with normal-renin essential hypertension. The furosemide test had a sensitivity of 75%, a specificity of 64%, a positive predictive value of 69% and a negative predictive value of 70%.

Blood pressure response to angiotensin converting enzyme inhibitor in essential hypertension: its relation to the renin status and natriuresis during acute sodium loading

We examined the antihypertensive response to enalapril and its relation to the changes of the renin-angiotensin-aldosterone axis (RAA) in essential hypertensive patients. The responders, whose blood pressure reduced after enalapril administration, had significant elevation of plasma renin activity after enalapril (7.5 +/- 4.0 to 31.9 +/- 10 ng/mL/h, p < 0.05). There was no significant change in the plasma renin activity of the nonresponders (3.0 +/- 1.0 to 5.6 +/- 1.9 ng/mL/h). Natriuretic response to acute salt loading was compared between the two subgroups. The natriuresis on acute salt loading of nonresponders was better than that of the responders (82.9 +/- 13.2 vs 44.5 +/- 5.7 mmol/4h, p < 0.05). These results imply that the RAA and extracellular fluid volume both contribute in different ways to the maintenance of high blood pressure in different subgroups of essential hypertension.

Heterogeneous blood pressure response to furosemide and captopril in primary aldosteronism

The hypertension associated with primary aldosteronism (PA) is often regarded as volume dependent/salt-sensitive. However, not all patients sustain an increase in blood pressure upon sodium loading. In order to examine the sodium sensitivity in PA, 21 patients with aldosteronoma were tested for acute hypotensive response to intravenous furosemide and oral captopril. Ten patients having a decrease in mean blood pressure (MBP) exceeding 5% at the second hour after a 20 mg furosemide injection were defined as diuretic-responders (DR), while the remainder were defined as diuretic-non-responders (DN). The DR group had a higher baseline MBP (135 +/- 6 [mean +/- SE] vs 121 +/- 4 mmHg, p < 0.05) and serum sodium concentration (145.7 +/- 1.4 vs 143.0 +/- 0.7 mmol/L, p < 0.05) than the DN group. The extent of natriuresis induced by furosemide was not different between the two subgroups. Following 100 mg of captopril administered orally, the DR group had a smaller change in MBP (%) than the DN group (3.08 +/- 5.14 vs -7.78 +/- 3.37, p < 0.05). According to the different BP responses to furosemide and captopril, we conclude that PA patients may be further divided into DR and DN. The DR group had a good response to diuretics whereas the DN group responded better to converting enzyme inhibitors. This classification of PA in terms of blood pressure response to furosemide may have therapeutic implications.

Atrial natriuretic peptide and blood pressure responses during acute sodium loading in patients with essential hypertension

Atrial natriuretic peptide (ANP) response during acute saline loading and its relationship to changes in blood pressure (BP) and sodium excretion were studied in 21 patients with essential hypertension (EH) and nine normotensive volunteers. Following 2 liters of isotonic saline infusion at a rate of 500 mL/hour, plasma ANP concentrations in patients with EH increased significantly from 69.9 +/- 6.0 (mean +/- SEM) to 103.6 +/- 17.1 pg/mL (p < 0.05) in the first hour and peaked at the second hour. In normal subjects, the increase in plasma ANP was not significant until the third hour of infusion (64.6 +/- 6.2 to 82.0 +/- 7.5 pg/mL, p < 0.05). Mean BP (MBP) remained stable and the natriuretic responses were similar in the two groups. However, hypertensive patients with a prompt rise in ANP during the initial two hours of infusion (fast responders) maintained a BP balance more efficiently than those with a delayed rise in ANP (slow responders), as the latter displayed a significant increase in MBP two hours after saline loading (126 +/- 5 to 133 +/- 5 mmHg, p < 0.05). Fast responders also had a greater percent of suppression of plasma aldosterone (-49.7 +/- 9.2 vs 15.9 +/- 42.0%, p = 0.05) one hour after saline loading, and a higher increment of natriuresis (263.9 +/- 43.8 vs 97.5 +/- 27.4%, p < 0.025) in the second hour of infusion than slow responders. Our results indicate that during acute saline loading, patients with EH have a faster and greater rise in plasma ANP than normotensives.(ABSTRACT TRUNCATED AT 250 WORDS)

Changes in renin activity, aldosterone level and electrolytes in pregnancy-induced hypertension

In order to observe the sequential changes in the renin-angiotensin-aldosterone system (RAAS) in hypertensive pregnancies, blood and urine samples of pregnant women were collected every four weeks from the 20th week of gestation to the fourth week after delivery in a consecutive and prospective study. Nine subjects developed pregnancy-induced hypertension in later gestation, and six of them with proteinuria were classified as having preeclampsia. The gestational ages at the onset of hypertension were the 28th week for one patient, the 32nd week for three patients and the 36th week for five patients. Plasma renin activity in most of the cases decreased to non-pregnant levels after hypertension was established, while the plasma aldosterone level did not. Marked variations in daily sodium and potassium excretion were observed at the various gestational weeks, while serum concentrations of these electrolytes changed only within a narrow range. No correlation between the changes in RAAS and electrolytes were shown in our cases.

Renin suppressibility and blood pressure response during acute sodium loading in patients with essential hypertension

Sequential changes in renin-aldosterone secretions and blood pressure (BP) response during acute sodium (Na) loading were studied in 50 patients with essential hypertension (EH) and nine normotensive volunteers. Following an infusion of 2 L of isotonic saline at a rate of 500 mL/h, plasma renin activity (PRA) and the plasma aldosterone concentration (PAC) were similarly suppressed, while sodium excretion appreciably increased in hypertensive as well as normotensive subjects. When patients were divided into two subgroups according to the extent of renin suppression, 26 were classified as adequate responders with the proportion of decrement of PRA at the end of the infusion exceeding 50% of the baseline values, while 24 were inadequate responders with a decrement of less than 50%. The extent of renin suppression was consistently greater in adequate responders than in inadequate responders throughout the course of infusion. Adequate responders also had a higher pre-saline PRA and attained a smaller post-saline natriuretic response than inadequate responders. Although the mean BP in both subgroups remained stable at all periods, inadequate responders had a minor but significantly higher percent of increment of MBP at the end of the infusion than adequate responders (3.6 +/- 2.0 vs -1.7 +/- 1.4%, p < 0.05). These results suggest that renin suppressibility during acute Na loading may be either linked with maintenance of BP homeostasis or may merely reflect the sodium-volume status of essential hypertension, with patients with greater suppression of renin being more Na-volume resistant than those with less inhibition.

The acute effect of nicardipine on the renin-angiotensin-aldosterone system in salt-sensitive essential hypertension

To determine the role of the renin-angiotensin-aldosterone (RAA) system in the acute effect of calcium channel blockers, we examined the acute effect of 40 mg nicardipine in 21 essential hypertensive patients. Nine patients whose mean blood pressure (MBP) decreased more than 5% at 2 hours after 20 mg furosemide i.v. were classified as salt-sensitive (SS); the remainder as salt-resistant (SR). The percentage decrease of MBP with nicardipine was not different between the two subgroups (12.4 +/- 2.5% for SS, and 17.7 +/- 4.1% for SR). The percentage decrease of MBP correlated with the pretreatment MBP (r = 0.67, p < 0.001), but not with the basal plasma renin activity (PRA), plasma aldosterone concentration (PAC), or natriuretic response. A significant increase of heart rate was noted in SR (31.2%) but not in SS (6.5%), and was associated with a higher increase of PRA in SR (90.7%) than in SS (25.5%). A correlation between the increase of PRA and the percentage increase of heart rate was noted (r = 0.77 p < 0.001). Decrease of PAC was observed in SS but not in SR until the third hour. The 3-hour sodium excretion was slightly greater in SR than in SS (59.9 +/- 9.1 vs. 35.1 +/- 3.0 mEq; p < 0.05). In summary, the acute hypotensive effect of nicardipine is dependent upon the vascular tone regardless of the status of the RAA system. An increase in PRA by nicardipine resulting from a baroreflex mechanism may counteract the inhibitory effect of aldosterone secretion by nicardipine. The unchanged PRA in SS is due to their blunted baroreflex control of heart rate. Mechanisms other than the change in the RAA system by nicardipine may account for the acute natriuretic effect.

Effects of age and posture on plasma active renin and plasma inactive renin in normal subjects

To investigate the effects of age and posture on plasma active and inactive renin, we measured the plasma active renin concentration (ARC) and inactive renin concentration (IRC) in 81 healthy subjects. The subjects were divided into five groups according to age and body position at the time the blood was taken. Group I included 15 five-day-old newborns in a supine position. Group H included 18 adults, aged from 20 to 50 years, who were in a supine position. Group III included 21 adults, over 50 years old, who were in a supine position. Group IV included 20 adults, aged from 20 to 50 years, who were in an upright position. Group V included 19 adults, over 50 years old, who were in an upright position. Twelve subjects were included in Groups II and IV. Plasma active renin was measured by the amount of angiotensin I general when an exogenous renin substrate was added. Plasma inactive renin was activated by trypsin. The results showed that, in a supine position, both ARC and IRC were significantly higher in newborns (Group I) than in the two adult groups (Groups II and III). The mean of the ARC/TPRC (total plasma renin concentration) ratio was lower in adults over 50 years old (Group III) than in those from 20 to 50 years old (Group II), but the difference was not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma renin activity, aldosterone level, serum and urinary electrolytes in normal pregnant women aged 35 and older

Plasma renin activity (PRA), the plasma aldosterone (PA) level, and serum and urinary electrolytes were measured in 39 elderly pregnant women of greater than or equal to 35 (Group 1) and in 60 pregnant women less than 35 (Group 2) every four weeks from the 20th week of gestation to the fourth week postpartum. The PRA and PA levels increased in both groups. The PA levels increased after the 20th week and reached a peak at the 32nd week of gestation, while PRA decreased after the 20th week of gestation. This dissociation was observed in both groups. Daily urinary sodium excretion in Group 1 was higher than that of Group 2, while daily potassium excretion was not different between the two groups. Higher aldosterone secretion was observed after the 20th week of pregnancy in Group 1. It is concluded that pregnancy in older women is associated with higher sodium excretion and aldosterone secretion.

Exaggerated natriuresis in primary aldosteronism

Acute response in blood pressure (BP) and natriuresis to saline infusion was evaluated in 16 patients with primary aldosteronism caused by aldosteronoma (PA) and 12 patients with salt-sensitive essential hypertension (SSEH). Salt-sensitivity was defined by a decrease in mean BP exceeding 5% at the second hour after a 20 mg furosemide injection. Plasma renin activity (PRA), plasma aldosterone concentration (PAC) and urine electrolytes in response to saline infusion were determined. During a 2-liter isotonic saline infusion, a similar degree of natriuresis and change in BP were observed in PA and SSEH patients. A significantly inverse correlation between the increase in mean BP and the degree of natriuresis at the end of the infusion was found in patients with SSEH (r = -0.80, p less than 0.01). No correlation was observed between these parameters in patients with PA (r = 0.28, p greater than 0.05). These results suggest that hypernatriuresis in SSEH may play a protective mechanism against abrupt increases in BP and volume during acute saline loading. This protective mechanism was not evident in patients with PA.

Sequential changes in plasma renin activity and aldosterone level during pregnancy

Sequential changes in plasma renin activity (PRA) and the plasma aldosterone (PA) level were studied prospectively in 101 patients at Taipei Municipal Women and Children Hospital from the 20th week of gestation to the 4th week postpartum. Average maternal age was 31.8 years old and average fetal birth weight was 3,235 g. The PRA and PA levels during pregnancy were higher than those of the normal nonpregnant women. PRA decreased gradually from the 20th week of gestation and dropped markedly after delivery. The PA level increased after the 20th week of gestation and peaked at the 32nd gestational week, then returned to the nonpregnancy level after delivery. A dissociation between the PRA and PA levels after the 28th week of gestation was observed. Possible causes for this dissociation are discussed. This study provides reference data on PA and PRA levels during the course of a normal pregnancy for use in further studies on abnormal gestation.

Changes in plasma active and inactive renin and prekallikrein during hemodialysis

To investigate the physiologic role of plasma inactive renin and its relationship to plasma kallikrein, we measured the changes in plasma active renin, inactive renin and prekallikrein levels in 14 uremic patients before and after hemodialysis. Blood was collected before, during and after hemodialysis, and prior to the next dialysis session. Plasma active renin was measured by radioimmunoassay of generated angiotensin I after addition of an exogenous substrate. Plasma inactive renin was activated by trypsin. Plasma prekallikrein was measured by the kallikrein-like activity on synthetic substrate S-2302 after activation of prekallikrein. The results showed that there was no change in blood pressure before, during or after dialysis, whereas the change in body weight after dialysis was significant. There was also no significant difference in the plasma active renin, inactive renin and prekallikrein levels for any of the collection periods. Plasma active renin was significantly correlated with inactive renin. The correlation between the active renin/total renin ratio and the plasma prekallikrein level was also not significant. These results suggest that in uremic patients undergoing chronic hemodialysis, the response of the renin system to acute plasma volume change is blunted. These data only provide evidence that plasma active renin is linked with inactive renin, but provide no evidence to support the idea that plasma inactive renin is a precursor of active renin or that plasma kallikrein is related to activation of inactive renin in vivo.

Comparison between spot urine and overnight urine in the estimation of 24-hour excretion of urine protein, sodium and kallikrein

To compare the value of spot urine and overnight 9-hour urine in the estimation of 24-hour urinary sodium excretion (UNaV), protein excretion (UpV) and kallikrein excretion (UKaV), we measured the concentration of sodium, protein, kallikrein and creatinine in spot urine, overnight 9-hour urine, and 24-hour urine samples obtained from 21 patients with various renal diseases. They ranged in age from 16 to 75 years with 10 males and 11 females. Urinary protein was measured by the Coomassie Blue dye-binding method. Urinary kallikrein activity was measured by assay of its amidase activity on synthetic substrate S-2266. The results showed that the 9-hour UpV and 9-hour urine P/Cr ratio was better correlated with the 24-hour UpV than the spot urine P/Cr ratio (at 9-11 AM), and the 9-hour UKaV and spot urine Ka/Cr ratio were better correlated with the 24-hour UKaV than the 9-hour Ka/Cr ratio. Only the 9-hour UNaV was correlated with the 24-hour UNaV. We conclude that overnight 9-hour urine, in view of its lower cost, equal effectiveness and convenience, is the best method to substitute for 24-hour urine collection in the evaluation of Na, P and Ka excretion in patients with renal diseases.