Improving diet recipe and cooking methods attenuates hyperphosphatemia in patients undergoing peritoneal dialysis.

BACKGROUND AND AIMS: Hyperphosphatemia is an independent predictor for cardiovascular and all-cause mortality in patients undergoing peritoneal dialysis (PD). The study aimed to investigate the effect of dietary intervention on reducing serum phosphate concentration in hyperphosphatemic PD patients. METHODS AND RESULTS: In this single-center clinical trial, 97 prevalent PD patients with serum phosphate concentration ≥ 1.6 mmol/l were allocated to the intervention (n = 48) or control (n = 49) group and followed up for 1 year. In addition to phosphate binder (calcium carbonate) therapy, patients in the intervention group were intensively educated to reduce phosphate-rich food intake and improve cooking methods. While stable in the control group (1.97 ± 0.20 to 1.94 ± 0.35 mmol/l, p > 0.05), the serum phosphate concentration decreased significantly in the intervention group (1.98 ± 0.28 to 1.65 ± 0.33 mmol/l, p = 0.015) concurrently with the drop in dietary phosphate intake (13.03 ± 3.39 to 10.82 ± 3.00 mg/kg ideal body weight/day, p = 0.001). Moreover, after 6 months of intervention, fewer patients needed to use calcium carbonate (from 64.6% to 41.5%, p = 0.029) and the medicine dose reduced significantly (from 2.25 (0, 3.94) to 0 (0, 1.50) g/day, p < 0.001). CONCLUSIONS: Our data indicated that intensive dietary intervention of reducing phosphate-rich food intake and improving cooking methods attenuated hyperphosphatemia in PD patients. It suggests that regular assessment of dietary phosphate intake and modification of diet recipe and cooking methods are essential for hyperphosphatemia treatment in PD patients in addition to phosphate binder therapy.

A combination of a PPAR-gamma agonist and an angiotensin II receptor blocker attenuates proinflammatory signaling and stimulates expression of Smad7 in human peritoneal mesothelial cells.

BACKGROUND: Human peritoneal mesothelial cells (HPMCs) have been shown to regulate the inflammatory response and the subsequent peritoneal extracellular matrix accumulation (ECM) induced by bio-incompatible peritoneal dialysis solutions. Recently, attention has been given to the possible antiinflammatory effect exhibited by angiotensin receptor blockers (ARB) or PPAR-gamma agonists in several tissues including glomerular. As no data on the potential role of these commonly used drugs in reducing peritoneal fibrosis exist, we examined the in vitro effects of an ARB (losartan) and a PPAR-gamma agonist (rosiglitazone) on inflammatory and profibrotic pathways in cultured HPMCs subjected to high glucose. METHODS: HPMCs were incubated for 48 hours with 3 different concentrations of glucose: 5 mM (G5), 50 mM (G50) and 100 mM (G100), as well as G50 with either losartan (5 or 10 microM) and/or rosiglitazone (1 or 10 microM). IL-6, IL-8, VEGF and TGF-beta1 in the supernatants were measured by cytokine multiplex assays or ELISA. Smad7, the inhibitor of the TGF/Smad signaling pathway, was measured using immunocytochemistry. RESULTS: All the measured cytokines increased in proportion to increased concentration of glucose. Unexpectedly, this effect was not inhibited, but rather further enhanced, by rosiglitazone and losartan separately. However, only the combination of the two drugs had an inhibitory effect on TGF- beta1 and IL-6, while the expression of inhibitory Smad7 was increased. CONCLUSION: We conclude that high glucose exposure stimulates an inflammatory response in HPMCs in a dose-dependent manner. Rosiglitazone and losartan appear to have synergetic effects which could decrease fibrosis by inhibiting inflammation and regulating the TGF/Smad signaling pathway, but further studies are needed to elucidate the complex pathways modulated by these drugs.

Differential inhibition of alpha 2-adrenoceptor-mediated pressor responses by (+)- and (-)-verapamil in pithed rats.

The inhibitory effects of (+)- and (-)-verapamil on the hypertensive responses brought about by the alpha 2-adrenoceptor agonist B-HT 920 were investigated in pithed normotensive rats. (-)-Verapamil was found to be about 4 times more potent with respect to depressing alpha 2-pressor responses compared with (+)-verapamil. To rule out the effect of 'unspecific' vasodilatation after the administration of the stereoisomers of verapamil, vasopressin was continuously infused into the carotid artery of pithed rats in a separate series of experiments. In the course of this vasopressin infusion, new inhibitory activities of the stereoisomers of verapamil on alpha 2-adrenoceptor-mediated pressor responses were determined. Under these circumstances, the potency ratio of (-)- vs (+)-verapamil was about 7. With the aid of a radioligand binding assay using [3H]clonidine to identify alpha 2-adrenoceptors, low affinities were measured for the stereoisomers of verapamil. A Ki = 6170 nM for (-)-verapamil and a Ki = 41700 nM for (+)-verapamil were calculated. The results indicate that the interaction between alpha 2-adrenoceptor-mediated pressor responses and calcium entry blockers, such as verapamil, is a stereoselective event.

Inhibition of the effect of high glucose on the expression of Smad in human peritoneal mesothelial cells.

OBJECTIVE: As high glucose (HG) concentration in peritoneal dialysis (PD) solution is thought to contribute to peritoneal fibrosis, and angiotensin II receptor blockers (ARBs) may have a key role in preventing fibrosis as they may inhibit the TGF-beta1-Smad pathway, the aims of this in vitro study were to investigate 1) if HG affects the expression of Smad in human peritoneal mesothelial cells (HPMCs) and 2) if ARB (losartan) can inhibit this effect METHODS: HPMCs, obtained from non-renal patients undergoing elective abdominal surgery, were stimulated by HG solutions with different concentrations (1.5%, 2.5%, 4.25%) of dextrose and mannitol, and by solutions containing combination with dextrose and losartan. The supernatant was assayed for TGF- beta1 by ELISA and cells were collected for the analysis of Smad family by RT-PCR and Western Blot. RESULTS: 1) HG up-regulated the expression of Smad2 on both gene and protein levels, especially in 2.5% and 4.25% dextrose groups (P<0.05), and also stimulated the expression of Smad4 in 4.25% dextrose group. However, the expression of Smad3 was not affected. 2) High osmolality as such (using mannitol) did not affect the TGF-beta1-Smad signaling pathway. 3) Losartan inhibited the expression of Smad2 on the gene level but not on the protein level. 4) HG up-regulated the level of TGF-beta1 with increasing dextrose concentration, while losartan partially inhibited this effect of HG on releasing of TGF-beta1. CONCLUSION: A high glucose solution up-regulated the expression of Smad2 and Smad4, suggesting that the TGF-beta1-Smad pathway could be involved in the fibrosis of the peritoneum during PD. As losartan inhibited the expression of Smad2 on the gene level and reduced the concentration of TGF-beta1 in our study, the results of this in vitro study suggest that the use of angiotensin II receptor blockers might represent a possible way to prevent and treat peritoneal fibrosis in PD patients. However, further studies in vivo are needed to confirm this hypothesis.

[Characterization of outward current in mouse ventricular myocytes].

Depolarization-activated, calcium-independent outward currents (Iout) in enzymatically dispersed mouse ventricular myocytes were characterized by whole-cell recording technique. During brief depolarizations to potentials positive to -50 mV, outward K+ currents in these cells rise rapidly to a peak followed by a slower decay to an apparent plateau. The relative peak to plateau amplitudes in a single cell varied as a function of the holding potential (HP) from which the currents were evoked. Reversal potentials for the peak and plateau components were -64.3 +/- 3.9 mV and -53.3 +/- 2.9 mV, respectively (uncorrected for junction potentials). The outward current decay is well described by double exponential fits, whereas the time course of peak Iout decay following a 500 ms prepulse is best fitted by single exponential function, indicating the presence of two distinct components, IKf and IKs, of the outward currents in mouse ventricular cells. Application of 4-AP were accompanied by a marked attenuation of peak Iout and plateau Iout, indicating that both IKf and IKs display similar sensitivities to 4-AP. The steady state inactivation of IKf is found incomplete within the test potential range (-80 - +30 mV) owing probably to the fact that the APD of mouse myocardium is too short.

[Effects of 1-(2,6-dimethylphenoxy)-2-(3,4-dimethoxyphenylethylamino) propane hydrochloride on proliferation of vascular smooth muscle cells and PDGF-B, bFGF, c-sis, c-myc in spontaneously hypertensive rat].

In order to determine the effects of 1-(2, 6-dimethylphenoxy)-2-(3, 4-dimethoxyphenylethylamino) propane hydrochloride(DDPH) on proliferation of vascular smooth muscle cells(VSMC), growth factor PDGF-B, bFGF and expression of oncogene c-sis and c-myc in spontaneously hypertensive rat(SHR), 3H-thymidine(3H-TdR) incorporation, electronic microscopy, immunohistochemistry and in situ hybridization assays were used. The results showed that after DDPH administration (50 mg i.g. q.d. x8 wk to SHR), morphological change of VSMC was antagonized, blood pressure and 3H-TdR incorporation were significantly reduced. Furthermore, DDPH was shown to reverse the enhanced antigen PDGF-B and bFGF and reverse the reduced expression of oncogene c-sis and c-myc in SHR. These results suggest that DDPH may inhibit VSMC proliferation in SHR, which may be relevant to the molecular biological mechanism of growth factors and oncogene control.

[Synthesis and antihypertensive activity of some phenoxyalkylamine compounds].

Nine new compounds were synthesized and tested for their alpha-adrenoceptor affinity and antihypertensive activity together with 5 other previously reported compounds. Compounds I, IIa, IIb and IIIa showed high alpha-adrenoceptor affinity and strong antihypertensive activity.

[Immunohistochemical and quantitative morphological studies of duct-acinar dysplasia in the prostate].

A series of 56 cases of prostatic adenocarcinoma and 48 cases of benign prostate hyperplasia were studied with histochemical, immunohistochemical methods and Feulgen-Image Analysis Technique. Duct-acinar dysplasia (DAD) was found in 81.8% of the prostate adenocarcinoma cases collected, but only in 47.9% of the benign hyperplasia cases. The frequency and extent of disruption of basal cell layer increased coincidently with the progressive increase of DAD grading. Intraluminal acid mucin and metachromasia stained with toluidine blue around the acini were identified in DAD. Immunohistochemical staining for prostatic acid phosphatase, cytokeratin, vimentin and UEA-1 receptor changed in DAD cells. The nuclear areas, DNA content and ploidy, mean numbers of AgNOR in DAD cells were higher than those in benign hyperplasia of the prostates and lower than those in adenocarcinomas, which indicates the possession of premalignant behavior of prostatic carcinoma.

Induction treatment of proliferative lupus nephritis with leflunomide combined with prednisone: a prospective multi-centre observational study.

To evaluate the efficacy and safety of leflunomide in the treatment of proliferative lupus nephritis, a prospective multi-centre observational study was conducted. Patients with biopsy proven proliferative lupus nephritis were assigned to receive either leflunomide or cyclophosphamide with concomitant prednisone. Leflunomide was given orally with a loading dose of 1 mg/kg/day for 3 days followed by 30 mg/day. Intravenous cyclophosphamide was administered monthly at a dose of 0.5 g/m2 of body-surface area. A total of 110 patients were enrolled, 70 in the leflunomide group and 40 in the cyclophosphamide group. The complete remission rate in the leflunomide group was 21% and partial remission rate 52%, as compared with 18% and 55%, respectively, in the cyclophosphamide group. Renal parameters and systemic lupus erythematosus disease activity index improved significantly and similarly in both groups. Serum creatinine decreased or stabilized in both treatment groups. No significant difference was noted with respect to clinical outcome between groups. Repeat biopsy also showed a significant reduction of active lesions in kidney pathology after 6 months of leflunomide treatment. Major adverse events, similar in both treatment groups, included infection, alopecia and hypertension. Leflunomide, compared with cyclophosphamide, in combination with prednisone was effective in the induction therapy of proliferative lupus nephritis and was generally well-tolerated.

Effects of isoliensinine on angiotensin II-induced proliferation of porcine coronary arterial smooth muscle cells.

The inhibitory effects of isoliensinine (IL), a bisbenzylisoquinoline alkaloid extracted from the seed embryo of the traditional chinese medicinal herb Nelumbo nucifera Gaertn, on the proliferation of porcine coronary arterial smooth muscle cells (CASMCs) induced by angiotensin II(Ang II) and its mechanisms of action were investigated. Counting cultured cell number, MTT assay, immunohistochemical method and Western blot were adopted. Ang II 0.1 micromol l (-1) significantly evoked CASMC proliferation by 42%, which could be dose-dependently inhibited by IL 0.01-3 micromol l (-1) and the percentage of inhibition of IL 0.1 micromol l (-1) was 25%. Irbesartan (Irb) 0.1 micromol l (-1) inhibited CASMC proliferation by 22%. IL or Irb 0.1 micromol l (-1) decreased Ang II-induced overexpression of Platelet-derived growth factor (PDGF)-beta and basic fibroblast growth factor (bFGF), respectively. Both of them also declined c-fos, c-myc and hsp70 overexpression, respectively. At the same concentration, the inhibitory effects of IL on PDGF-beta were even stronger than those of Irb (P < 0.05). In summary, the data showed that IL possesses an anti-proliferative effect, which is related to the decrease of the overexpression of growth factors PDGF-beta, bFGF, proto-oncogene c-fos, c-myc and hsp70.

DDPH inhibited L-type calcium current and sodium current in single ventricular myocyte of guinea pig.

AIM: To investigate the effects of 1-(2, 6-dimethylphenoxy)-2-(3,4-dimethoxyphenyl-ethylamino)propane hydrochloride (DDPH) on L-type calcium current (ICa) and sodium current (INa), and to compare its inhibitory potency with verapamil and mexiletine. METHODS: Whole-cell patch clamp technique was used to record ICa and INa in a single ventricular myocytes of guinea pig. RESULTS: (1) DDPH (3 - 300 micromol . L-1) decreased ICa at 0 mV in a concentration-dependent manner with an IC50 value of 28.5 micromol . L-1 (95 % confidence limits: 14.3 - 42.7 micromol . L-1, n = 8 cells from 8 guinea pigs). Verapamil (0.3 - 30 micromol . L-1) reduced ICa with an IC50 value of 1.8 micromol . L-1 (95 % confidence limits: 1.3 - 2.3 micromol . L-1, n = 6 cells from 6 guinea pigs). Mexiletine 100 micromol . L-1 did not affect ICa (n = 5 cells from 5 guinea pigs, P > 0.05). The degree of use-dependent blocking effect of DDPH 30 micromol/L on ICa was 58 % +/- 13 % (n = 5 cells from 5 guinea pigs, P < 0.01) at 1 Hz and 76 % +/- 11 % (n = 5 cells from 5 guinea pigs, P < 0.01) at 3 Hz. (2) DDPH (20 - 320 micromol . L-1) could also block INa in a concentration-dependent manner with an IC50 value of 89.0 micromol . L-1 (95 % confidence limits: 68.7 - 109.3 micromol . L-1, n = 9 cells from 9 guinea pigs). The IC50 value of mexiletine was 32.2 micromol . L-1 (95 % confidence limits: 11.7 - 52.7 micromol . L-1, n = 5 cells from 5 guinea pigs). Verapamil at the concentration of 10 micromol . L-1 did not affect INa (n = 5 cells from 5 guinea pigs, P > 0.05). The blocking effect of DDPH 80 micromol/L on INa was non use-dependent. CONCLUSION: DPH exhibited inhibitory effects on both ICa and INa, but its inhibitory effect on ICa was weaker than verapamil, and on INa was weaker than mexiletine.

Effects of selective alpha 1- and alpha 2-adrenoceptor agonists on the physiologic properties of rat left atria.

The effects of the selective alpha 1-adrenoceptor agonist, phenylephrine, and the alpha 2-adrenoceptor agonist, B-HT933, on the contractility, excitability, automaticity, and functional refractory period in the isolated rat left atria were investigated. For the depletion of catecholamine in rat left atria and the blockade of intra- and extraneuronal uptake of catecholamine, reserpine (10 mg/kg, i.p.) was given to rat 16-18 h before the experiment; cocaine (30 microM) and hydrocortisone (30 microM) were continuously present in the bath. The positive inotropic effect of phenylephrine was competitively antagonized by prazosin with a pA2 value of 9.29. The excitability of rat left atria was not affected by phenylephrine, whereas the automaticity of left atria induced by adrenaline was enhanced and the functional refractory period of left atria was prolonged by phenylephrine. The prolongation of functional refractory period caused by phenylephrine was competitively inhibited by prazosin with a pA2 value of 8.15. B-HT933 was not able to induce any change in the contractility, excitability, automaticity, and functional refractory period of rat left atria under the same conditions. The results indicated that the cardiophysiological effects on rat left atria caused by stimulation of postsynaptic alpha-adrenoceptor was mediated by alpha 1-type receptors while postsynaptic alpha 2-type receptors are not of functional importance on rat left atria.

[Effects of alpha-adrenoceptor agonists on cardiac function and blood pressure in rats].

In rat working hearts, alpha 1-adrenoceptor agonist phenylephrine increased LVP, +/- dP/dtmax, ABF and HR in the presence of propranolol. But alpha 2-adrenoceptor agonist B-HT 920 was ineffective. The changes induced by phenylephrine were antagonized by prazosin. In normotensive pithed rats, iv methoxamine dose-dependently increased LVP, +/- dP/dtmax, LVEDP, SAP and DAP. The changes in haemodynamics elicited by iv methoxamine were also antagonized by pretreatment with prazosin, and were attenuated by nifedipine (1 mg/kg, ia). In these two experiments, the increase in HR developed more slowly. The results suggest that postjunctional alpha 1-adrenoceptors, which exist in rat myocardium, produce a positive inotropic effect, which is possibly dependent on influx of extracellular calcium. Postjunctional alpha 2-adrenoceptors-mediated effects were not found in rat myocardium in our functional studies.

Modulation by muscarinic receptor antagonists on negative chronotropic effects of tetrandrine.

AIM: To investigate the influence of selective antagonist for muscarinic (M) receptor subtype on tetrandrine (Tet) reducing heart rate, inhibiting sinoatrial node (SAN) function, and its ionic mechanism. METHODS: Effects of reducing heart rate of Tet were maintained in isolated right atrium and pithed rats. Modification on action potentials (AP) of SAN cells and L-type calcium current (ICa-L) by Tet were recorded by means of standard microelectrode and patch-clamp whole cell recording techniques. RESULTS: Tet inhibited spontaneous beating rate of isolated right atrium (EC50, 23.7 mumol.L-1) and reduced heart rates in pithed rats in a concentration-dependent manner (EC50, 18.6 mg.kg-1). Automaticity of SAN was inhibited by Tet. AP upstroke velocity (Vmax), spontaneous depolarization rates in phase 4 (SP4) were decreased and sinus cycle length (SCL) was prolonged when treated with Tet. Tet (30 mumol.L-1) caused a reduction in peak value of ICa-L from (1275 +/- 190) pA to (498 +/- 94) pA in isolated single cardiomyocyte. Atropine and AF-DX 116 (M2 subtype selective antagonist) could attenuate such effects of Tet in a competitive mode. CONCLUSION: Negative chronotropic effects of Tet are due to its inhibition of ICa-L. Modification on ICa-L is the major mechanism of M receptor modulating Tet effects.

[Effects of neferine on heart electromechanical activity in anaesthetized cats].

Neferine, an alkaloid extracted from the green seed embryo of Nelumbo nucifera Gaertn, has been shown to have anti-arrhythmic action. Neferine 1-10 mg/kg iv dose-dependently decreased the monophasic action potential amplitude (MAPA), prolonged the monophasic action potential duration (MAPD). It also decreased LVP, dP/dt, prolonged SCL, and reduced arterial blood pressure in a dose-dependent manner. These effects were similar to those of quinidine, and different from tetrandrine. The latter had an inhibitory effect on LVP and dP/dt, but had no influence on MAPA and MAPD. The results indicate that neferine and quinidine have similar effects on heart electro-mechanical activity.