Identification of differently expressed microRNAs in keloid and pilot study on biological function of miR-199a-5p / 中华整形外科杂志

<p><b>OBJECTIVE</b>To screen out related microRNAs in keloid tissue, and identify their effect on the proliferation of keloid fibroblasts.</p><p><b>METHODS</b>8 cases of keloid tissue and 8 cases of normal skin tissue were collected as specimens. The differently expressed miRNA in keloid tissue from normal skin tissue were screened out with gene chip( Exiqon company), which was validated with quantitative real-time PCR. Then miRNA mimics was transfected into keloid fibroblasts line to stimulate high expression of mature miRNA in cells. The effect on the proliferation of fibroblasts in keloid was tested by Edu.</p><p><b>RESULTS</b>(1) A total of 17 differently expressed microRNAs were found, including miR-199a-5p. (2) The expression of miR-199a-5p had been verified by qRT-PCR to be down-regulated in keloid, which was consistent with the result of array. (3) The positive rate of EdU in miR-199a-5p mimics transfected group and negative control group was (20.72 +/- 2.50)% and (27.68 +/- 4.92)%, respectively. The proliferative rate of keloid fibroblasts turned down in miR-199a-5p-transfected group (t = 2.183, P = 0.047). Besides that, the cell cycle changed after transfection. The percentage of S and G2/M phase in miR-199a-5p mimics transfected group was 33.93 +/- 1.30 and 10.87 +/- 0.80, respectively, while it was 31.39 +/- 0.79 and 9.27 +/- 0.46 in negative control group, and the difference was statistically significant.</p><p><b>CONCLUSIONS</b>(1) The miRNA expression profile is different between keloid and normal skin; (2) The expression of miR-199a-5p is down-regulated in keloid and miR-199a-5p can affect the cell cycle and suppress proliferation of keloid fibroblasts. It indicateds that miR-199a-5p may be involved in regulating fibroblastic proliferation.</p>

Involvement of veratridine-induced increase of reverse Na(+)/Ca(2+) exchange current in intracellular Ca(2+) overload and extension of action potential duration in rabbit ventricular myocytes / 生理学报

The objectives of this study were to investigate the effects of veratridine (VER) on persistent sodium current (I(Na.P)), Na(+)/Ca(2+) exchange current (I(NCX)), calcium transients and the action potential (AP) in rabbit ventricular myocytes, and to explore the mechanism in intracellular calcium overload and myocardial contraction enhancement by using whole-cell patch clamp recording technique, visual motion edge detection system, intracellular calcium measurement system and multi-channel physiological signal acquisition and processing system. The results showed that I(Na.P) and reverse I(NCX) in ventricular myocytes were obviously increased after giving 10, 20 μmol/L VER, with the current density of I(Na.P) increasing from (-0.22 ± 0.12) to (-0.61 ± 0.13) and (-2.15 ± 0.14) pA/pF (P < 0.01, n = 10) at -20 mV, and that of reverse I(NCX) increasing from (1.62 ± 0.12) to (2.19 ± 0.09) and (2.58 ± 0.11) pA/pF (P < 0.05, n = 10) at +50 mV. After adding 4 μmol/L tetrodotoxin (TTX), current density of I(Na.P) and reverse I(NCX) returned to (-0.07 ± 0.14) and (1.69 ± 0.15) pA/pF (P < 0.05, n = 10). Another specific blocker of I(Na.P), ranolazine (RAN), could obviously inhibit VER-increased I(Na.P) and reverse I(NCX). After giving 2.5 μmol/L VER, the maximal contraction rate of ventricular myocytes increased from (-0.91 ± 0.29) to (-1.53 ± 0.29) μm/s (P < 0.01, n = 7), the amplitude of contraction increased from (0.10 ± 0.04) to (0.16 ± 0.04) μm (P < 0.05, n = 7), and the baseline of calcium transients (diastolic calcium concentration) increased from (1.21 ± 0.08) to (1.37 ± 0.12) (P < 0.05, n = 7). After adding 2 μmol/L TTX, the maximal contraction rate and amplitude of ventricular myocytes decreased to (-0.86 ± 0.24) μm/s and (0.09 ± 0.03) μm (P < 0.01, n = 7) respectively. And the baseline of calcium transients reduced to (1.17 ± 0.09) (P < 0.05, n = 7). VER (20 μmol/L) could extend action potential duration at 50% repolarization (APD(50)) and at 90% repolarization (APD(90)) in ventricular myocytes from (123.18 ± 23.70) to (271.90 ± 32.81) and from (146.94 ± 24.15) to (429.79 ± 32.04) ms (P < 0.01, n = 6) respectively. Early afterdepolarizations (EADs) appeared in 3 out of the 6 cases. After adding 4 μmol/L TTX, APD(50) and APD(90) were reduced to (99.07 ± 22.81) and (163.84 ± 26.06) ms (P < 0.01, n = 6) respectively, and EADs disappeared accordingly in 3 cases. It could be suggested that: (1) As a specific agonist of the I(Na.P), VER could result in I(Na.P) increase and intracellular Na(+) overload, and subsequently intracellular Ca(2+) overload with the increase of reverse I(NCX). (2) The VER-increased I(Na.P) could further extend the action potential duration (APD) and induce EADs. (3) TTX could restrain the abnormal VER-induced changes of the above-mentioned indexes, indicating that these abnormal changes were caused by the increase of I(Na.P). Based on this study, it is concluded that as the I(Na.P) agonist, VER can enhance reverse I(NCX) by increasing I(Na.P), leading to intracellular Ca(2+) overload and APD abnormal extension.

Low extracellular pH increases the persistent sodium current in guinea pig ventricular myocytes / 生理学报

Whole-cell and cell-attached patch-clamp techniques were used to record the changes of persistent sodium current (I(Na.P)) in ventricular myocytes of guinea pig to investigate the effect of low extracellular pH on I(Na.P) and its mechanism. The results showed that low extracellular pH (7.0, 6.8 and 6.5) obviously increased the amplitude of whole-cell I(Na.P) in a [H(+)] concentration-dependent manner. Under the condition of extracellular pH 6.5, I(Na.P) was markedly augmented from control (pH 7.4) value of (0.347+/-0.067) pA/pF to (0.817+/- 0.137) pA/pF (P<0.01, n=6), whereas the reducing agent dithiothreitiol (DTT, 1 mmol/L) reversed the increased IN(Na.P) from (0.817+/-0.137) pA/pF to (0.233+/-0.078) pA/pF (P<0.01 vs pH 6.5, n=6). Decreasing extracellular pH to 6.5 also increased the persistent sodium channel activity in cell-attached patches. The mean open probability and mean open time were increased from control value of 0.021+/-0.007 and (0.899+/-0.074) ms to 0.205+/-0.023 and (1.593+/-0.158) ms, respectively (both P<0.01, n=6), and such enhancement was reversed by application of 1 mmol/L DTT [to 0.019+/-0.005 and (0.868+/-0.190) ms, both P<0.01 vs pH 6.5, n=6]. Furthermore, protein kinase C (PKC) inhibitor bisindolylmaleimide (BIM, 5 micromol/L) reduced the enhanced mean open probability and mean open time at pH 6.5 from 0.214+/-0.024 and (1.634+/-0.137) ms to 0.025+/-0.006 and (0.914+/-0.070) ms, respectively (both P<0.01 vs pH 6.5, n=6). The results demonstrate that low extracellular pH markedly increases I(Na.P) in guinea pig ventricular myocytes, in which activation of PKC may be involved.

Calcium-dependent chloride channels in plasma membrane of oocytes from toad, Bufo bufo gargarizans / 生理学报

In this paper, membrane current properties of the fully-grown oocytes from toad, Bufo bufo gargarizans, were studied by using two-microelectrode voltage clamp technique. Axion of adult female toad was destroyed, and then ovarian lobes containing oocytes in stage I to VI were removed and incubated in Ca(2+)-free ND96 solution with collagenase (1.5 mg/ml) for 1 h. Subsequently, the oocytes were washed in Ca(2+)-free ND96 solution for 10 min to completely remove the follicular layer. For the experiments only the oocytes in stage V and VI were selected and used during 1 to 5 d. The membrane was depolarized from a holding potential of -80 mV to +60 mV in 10 mV step. It was found that a sustained outward current was elicited by depolarization. Potassium channel blockers (tetraethylammonium chloride, TEA, 10 mmol/L and 4-aminopyridine, 4-AP, 10 mmol/L) reduced the outward current to (23.4+/-0.72)% of the maximum. However, further addition of chloride channel blocker (5-nitro-2, 3-phenypropylamino benzoate, NPPB, 30 micromol/L) could almost completely block the outward current to (2.1+/-0.08)% of the maximum. In the presence of TEA and 4-AP, removal of extracellular Ca(2+) or adding verapamil (40 micromol/L), could also reduce the outward current to (2.2+/-0.04) % and (3.1+/-0.15) % of the maximum, respectively. It is concluded that calcium-dependent chloride channels exist in plasma membrane of Bufo bufo gargarizans oocytes, besides potassium channels.

Observation on hybrid bioartificial liver support systems in treating chronic severe hepatitis: a study of 60 cases / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To study the clinical efficacy of three kinds of hybrid bioartificial liver support systems (HBLSS) in treating chronic severe hepatitis.</p><p><b>METHODS</b>A bioartificial liver support system (BAL), comprising porcine hepatocytes and fiber tube style bioreactor, was constructed. Then three kinds of HBLSS were constructed: Molecular absorbent recirculating system (MARS) plus BAL; slow plasma exchange (SPE) plus continuous hemodiafiltration (CHDF) and BAL; and SPE plus hemoperfusion (HP) and BAL. One hundred-twenty patients in middle or late stages of chronic severe hepatitis were enrolled in this study. They were randomly divided into 6 groups: H1 group was treated with BAL+MARS, H2 with BAL+SPE+CHDF and H3 with BAL+SPE+HP (as treatment groups); C1 group was treated with MARS, C2 with SPE+CHDF and C3 with SPE+HP (as control groups). The changes in the clinical symptoms, in the hepatic encephalopathy stages, and in the serum total bilirubin (TBIL), the serum albumin (ALB), the prothrombin activities (PTA), endotoxin, ammonia, creatinine and a-fetal protein (AFP) were all observed before the treatment, right after it and 72 hours later. The improving and curing rates and the rates of side effect occurrences in each group were observed.</p><p><b>RESULTS</b>In all 6 groups, the patients' clinical symptoms ameliorated; their TBIL, endotoxin and ammonia levels decreased (P<0.05), and their PTA and AFP levels lowered significantly (P<0.05). But in the H1, H2 and H3 groups they were more distinctive than in the control groups. In H1 and H2 groups creatinine and ammonia levels were decreased more significantly than in the H3 group (P<0.05). The improving and curing rates of each group were 65 % (13/20), 60% (12/20), 45% (9/20), 45% (9/20), 40% (8/20) and 20% (4/20) respectively. No serious side effects were observed during the treatment.</p><p><b>CONCLUSION</b>In treating middle and late stage chronic severe hepatitis, the measures used in H1, H2 and H3 are better than those in C1, C2 and C3. Furthermore, H1 and H2 treatments can ameliorate hepatic and renal functions, prevent the development of multiple organ dysfunction syndrome, and are better than those used in H3.</p>

The effect of hypoxia-early reoxygenation on persistent sodium current in single ventricular myocytes of guinea pig / 中国应用生理学杂志

<p><b>AIM</b>To investigate the effect of hypoxia/early reoxygenation on persistent sodium current (I(Na.P)) in single ventricular myocytes of guinea pig and discuss its role and significance during this pathological condition.</p><p><b>METHODS</b>The whole cell patch clamp technology was used to record this current and study its change under the condition of hypoxia/reoxygenation model.</p><p><b>RESULTS</b>(1) With 0.5 Hz, 1 Hz and 2 Hz pulse frequency, the current density gap between the first and the eighth pulse of I(Na.P) was (0.021 +/- 0.014) pA/ pF, (0.097 +/- 0.014) pA/pF and (0.133 +/- 0.024) pA/pF (P < 0.01) respectively. (2) Depolarization with membrane holding potential of -150 - -80 mV respectively, I(Na.P) density attenuated gradually. (3) The amplitude of I(Na.P) was increased consistently with the prolongation of hypoxia time during hypoxia. (4) I(Na.P) was (0.500 +/- 0.125) pA/pF, (1.294 +/- 0.321) pA/pF and (0.988 +/- 0.189) pA/pF (P < 0.01, vs normoxia, respectively) during normoxia, hypoxia after 15 min and reoxygenation after 5 min, respectively.</p><p><b>CONCLUSION</b>These results indicate that I(Na.P) has great significance in arrhythmogenesis and calcium-overload, which causes the following postischemia and post hypoxia myocardial damage.</p>

Nitric oxide increases persistent sodium current of ventricular myocytes in guinea pig during normoxia and hypoxia / 生理学报

Whole cell patch-clamp technique was used to record the changes of persistent sodium current (I(Na.P)) and the effect of administered agents in ventricular myocytes of guinea pig to investigate the essence of I(Na.P) and mechanism of increased I(Na.P) of ventricular myocytes during hypoxia. The results showed: (1) Pro-NO L-arginine(L-Arg) and donor sodium nitroprusside (SNP) increased I(Na.P) in a concentration-dependent manner in normoxia. (2) I(Na.P) increased gradually with the prolongation of hypoxia time. After 15 min of hypoxia, administration of N(G)-nitro-L-arginine methyl ester (L-NAME), a NO synthase inhibitor, could not significantly recover the increased I(Na.P) [(1.344+/-0.320) vs (1.301+/-0.317) pA/pF, P>0.05, n=5]; (3) During hypoxia the perfusion solution with L-NAME decreased the increased I(Na.P), and the difference was significant compared with pure hypoxia [(0.914+/-0.263), n=5 vs (1.344+/-0.320) pA/pF, P<0.05, n=6], whereas the amplitude of I(Na.P) was still larger than that in normoxia [(0.914+/-0.263) vs (0.497+/-0.149) pA/pF, P<0.05, n=5]; (4) Reducing agent dithiothreitiol (DTT) not only recovered the increased I(Na.P) by L-Arg and administered SNP after hypoxia [(1.449+/-0.522) vs (0.414+/-0.067) pA/pF, P<0.01, n=6, and (1.786+/-0.636) vs (0.436+/-0.141) pA/pF, P<0.01, n=5, respectively], but also decreased the I(Na.P) in normoxia [(0.442+/-0.056) vs (0.396+/-0.057) pA/pF, P<0.01, n=6]. Our results suggest that hypoxia increases I(Na.P) of ventricular myocytes, which is induced by raised NO oxidating sodium channel protein in myocardial membrane during hypoxia. The activity of I(Na.P) in normoxia is related to the oxidation state of the channel protein.