Experimental study on the therapeutic effect of different bleaching methods on white-spot lesions of the enamel using optical coherence tomography / 口腔医学

Objective@#To investigate the efficacy of different bleaching methods on white-spot lesions of the enamel using optical coherence tomography and to evaluate its feasibility for monitoring the therapeutic effects on white-spot lesions. @*Methods@#Forty-eight sound premolars extracted for orthodontic reasons were selected and cut for 4 mm×4 mm×2 mm enamel blocks in buccal surfaces of the crowns. The samples were covered with acid-resistant varnish (except for the buccal surfaces) and immersed in demineralization solution for 18 days to establish the white-spot lesion models of the enamels. Samples were randomly divided into four groups (n=12). Group A was given demineralization only. Specimens in Group B, C and D were treated with 40% hydrogen peroxide, resin infiltration and 40% hydrogen peroxide combined with resin infiltration, respectively. Eight samples in each group were randomly selected. OCT was applied to observe the optical changes of the enamel surface and according to the OCT scanning results, the demineralization depth of enamel samples in each group was calculated. Then, the enamel blocks were embedded in epoxy resins, except the buccal surfaces, and measured for the microhardness values of the enamel surface by a microindentation hardness tester. Four samples in each group were cut longitudinally, and the ultrastructural changes of enamel samples in each group were observed by scanning electron microscope. @* Results@#OCT showed that the light scattering characteristics of enamel surface changed in all groups, and the bright layer was formed, but the thickness of bright layer in Group C and D was significantly lower than that in Group A and B (P<0.05). The microhardness values (kg/mm2) of the samples in Group A-D were (214.99±31.70), (250.66±33.64), (312.42±18.01) and(286.53±26.65), respectively. The microhardness of enamel surfaces in Group C and D was significantly higher than that in Group A and B (P<0.05), and the ultrastructure of enamel surfaces in Group C and D were more flat and dense in SEM observation (P<0.05). @*Conclusion@#The methods of resin infiltration therapy or 40% hydrogen peroxide combined with resin infiltration could effectively improve white-spot lesions of the enamel and the non-invasive OCT can be used as a better evaluation method for the diagnosis and treatment of white-spot lesions of the enamel.

Effects of Ca2+ and SA on physiological and photosynthesis of Platycodon grandiflorum under high temperature stress / 中国中药杂志

In order to reveal feasibility of different concentrations of Ca2+ and SA on Platycodon grandiflorum under high temperature stress, the effects of Ca2+ on physiological index and related photosynthetic parameters were studied. Pot cultured P. grandiflorum leaves under the same outdoor conditions were sprayed with CaCl2 and SA separately, and then placed in the high incubator [35 degrees C/25 degrees C (day/night), light intensity 3 600 lx], and sprayed with distilled water at 25 degrees C and under high temperature stress were set as the control. The related photosynthesis, relative conductivity, contents of proline, malondialdehyde, soluble protein, activities of SOD and CAT, ASA and GSH content were measured. The results show that the 6 mmol x L(-1) CaCl2 and 1.5 mmol x L(-1) SA enhanced the activities of SOD and CAT, the contents of proline and soluble protein, and effectively reduced the damage of heat stress on cell membrance. At the same time, the exogenous Ca2+ and SA increased the contents of chlorophyll and carotenoid, the efficiency of leaf photosynthesis and ASA and GSH content, and thus effectively resisted the oxidative stress caused by high temperatures, but with the increasing concentration of spraying, P. grandiflorum decreased the ability to resist high temperature stress. In conclusion, the foliage spraying CaCl2 and SA could reduce the damage of high temperature stress on P. grandiflorum leaves.

Induced pluripotent stem cells in spermatogenesis: Progress in current studies / 中华男科学杂志

Spermatogenesis is a complex process. Current knowledge about human spermatogenesis is mainly based on the mouse model while little is known about the initial stage of this fundamental process in humans. The establishment of the model of spermatogenesis in vitro may contribute to an overall understanding of male germ cell development, an insight into the mechanisms of infertility, and clinical management of male infertility. This review summarizes current knowledge about the generation of germ cell-like cells from induced pluripotent stem cells (iPSCs) in vitro and discusses the potential application of iPSCs in the treatment of male infertility.

Effect of antiarrhythmic peptide on ventricular arrhythmia induced by lysophosphatidic acid / 中华心血管病杂志

<p><b>OBJECTIVE</b>To investigate the effect and potential mechanism of lysophosphatidic acid (LPA) and antiarrhythmic peptide (AAP10) on rabbit ventricular arrhythmia.</p><p><b>METHODS</b>Twenty-four rabbits were randomly divided into three groups (n = 8 each): control group, LPA group and AAP10 + LPA group. Using arterially perfused rabbit ventricular wedge preparations, transmural ECG and action potentials from both endocardium and epicardium were simultaneously recorded in the whole process of all experiments with two separate floating microeletrodes. The incidence of ventricular arrhythmia post S1S2 stimulation was recorded. Protein levels of nonphosphorylated Cx43 and total Cx43 were evaluated by Western blot. The distribution of nonphosphorylated Cx43 was observed by confocal immunofluorescence microscopy.</p><p><b>RESULTS</b>Compared with the control group, the QT interval, endocardial action potential duration, transmural repolarization dispersion (TDR) and incidence of ventricular arrhythmia were significantly increased and nonphosphorylated Cx43 expression was significantly upregulated in the LPA group. Compared with the LPA group, cotreatment with AAP10 can reduce the QT interval, endocardial action potential duration, TDR and incidence of ventricular arrhythmia (25.0% vs 62.5%, P < 0.01) and downregulate nonphosphorylated Cx43.</p><p><b>CONCLUSIONS</b>LPA could promote the arrhythmia possibly by upregulating nonphosphorylated Cx43 and subsequent gap junction transmission inhibition. Gap junction enhancer AAP10 could attenuate the pro-arrhythmic effect of LPA probably by downregulating myocardial nonphosphorylated Cx43 expression.</p>

Effects of combined amiodarone and antiarrhythmic peptide use on the cardiac gap junctions and incidence of induced ventricular arrhythmias in healed myocardial infarction rabbit models / 中华心血管病杂志

<p><b>OBJECTIVE</b>The aim of this study is to observe the effect of combined amiodarone and antiarrhythmic peptide (AAP10) use on the incidence of induced ventricular arrhythmias in healed myocardial infarction (MI) rabbits.</p><p><b>METHODS</b>Twenty Japanese rabbits underwent thoracotomy without coronary artery ligation (Sham, group A), the middle left circumflex branch were ligated to induce MI in 180 Japanese rabbits. Eight weeks after operation, 124 rabbits survived MI operation and were divided into four groups: control group (group B, n = 31), amiodarone group (group C, n = 31), AAP10 group (group D, n = 31) and amiodarone plus AAP10 group (group E, n = 31). The A and B and D groups were treated with saline 2 ml/d, the C and E groups were treated with 2 ml saline containing amiodarone 100 mg×kg(-1)×d(-1). All rabbits were examined by echocardiogram at 12 weeks after operation, then anesthetized by sodium barbital, the left wedge ventricular preparations were cannulated and artery perfused by Tyrode's solution in vitro in the absence (Group A, B and C) and presence of AAP10 (500 nmol/L, Group D and E). The volume electrocardiogram, QT Interval, QRS interval, effective refractory period (ERP), the T-peak to T-end interval (T(p-e)), and ventricular tachycardia episodes induced by programmed stimulation were recorded. The T(p-e)/QT ratio was calculated. After perfusion, gap junctions protein connexin 43 (Cx43) expression was detected by Western blot and immunofluorescence.</p><p><b>RESULTS</b>The incidence of induced ventricular tachycardia episodes of group A, B, C, D, E was 0, 62.5%, 26.9%, 40.0%, 22.2% respectively. The incidence of induced ventricular tachycardia episodes of group E was less than group B. The T(p-e)/QT ratio in group B, C, D were greater than in group A. The T(p-e)/QT ratio of group E was less than group B. The myocardial Cx43 in the group B was down-regulated and disorganized compared to group A, up-regulated in group C and E compared to group B, up-regulated in group E compared to group D. The Cx43 in the heart of group D and E were well organized than in group B and C.</p><p><b>CONCLUSIONS</b>The artery perfused rabbits wedge preparations with healed myocardial infarction with high incidence of induced ventricular tachycardia episodes are good platform for ventricular arrhythmias research. Combined amiodarone and AAP10 use could decrease the T(p-e)/QT ratio and the incidence of induced ventricular tachycardia episodes. Amiodarone and AAP10 have synergistic effects on upregulating Cx43 and preventing ventricular arrhythmias in this rabbit model of healed myocardial infarction.</p>