Objective To investigate the potassium currents of the cardiac pacemaking cells induced and differentiated from rat mesenchymal stem cells (MSCs) modified by HCN4 gene. Methods Identified cardiac pacemaking cells were adopted as the experiment group, and the sinoatrial node cells of original infant rat cultured in the same period were regarded as the control group. Whole cell patch was used to measure the action potential of the pacemaking cells and sinoatrial node cells. Results Action potential of automatic depolarization at dilatation was recorded in both the differentiated cardiac pacemaking cells and sinoatrial node cells. There was no significant difference on amplitudes of resting potential, amplitudes and cycle of action potential [(-50?2.8) vs (-55?5.5),(-60?2.5) vs (-65?2.5),(240?57) ms vs (250?60) ms], but the field potential was much lower in cardiac pacemaking cells than the control group[(-30?2.5) vs (-55?5.5),P

Objective To investigate the effects of electrical stimulation on the differentiation of rat bone marrow mesenchymal stem cells (MSCs) to cardiomyocyte induced by 5-azacytidine in vitro. Methods MSCs from Sprague-Dawley (SD) rats were cultured and passed repeatedly to P3. MSCs were treated with 5-azacytidine (10 ?mol/L) and incubated for 24 h.The induced MSCs were divided to stimulated group and non-stimulated group, and every groups divided by incubated for 1,2,3 and 4 weeks were named as subgroup Ⅰ,Ⅱ, Ⅲ and Ⅳ respectively.MSCs of stimulated group were stimulated for 30 min every day by supra-threshold square biphasic pulses (2 ms duration, 1.5 Hz, 20 ?A), and the stimulation was initiated 1 d after inducing. Light and electronic microscope were used to identify the influences of characteristic morphological of MSCs in every subgroups,and immunocytochemistry was used to identify the expression of ?-actin,cTnT, Cx43 in MSCs. Results The growth of MSCs in stimulated group was better than that of non-stimulated group. MSCs of stimulated group exhibited differentiation into cardiomyocyte-like cell at 1 week after inducing, earlier than that of no-stimulated group (2 weeks). In stimulated subgroup Ⅰ, scattered myogenic structure was observed in the plasma of some cells under electronic microscope, and ?-actin,cTnT expressed in some cells, but not that be observed in non-stimulated subgroup Ⅰ. In cells of stimulated subgroups Ⅱ to Ⅳ, the expression level of ?-actin, cTnT, Cx43 of were all higher than that of non-stimulated subgroups respectively. Conclusion Electrical stimulation (simulating the heart beating) could redound differentiation of rat bone marrow mesenchymal stem cells (MSCs) to cardiomyocyte induced by 5-azacytidine in vitro.

Objective To study the effects of heart ischemia reperfusion on conductive function of atrioventricular node (AVN) in rabbits. Methods Animal models of ischemia reperfusion of AVN were established by ligating and reopening the right coronary artery of rabbits. A total of 60 adult rabbits were divided into control groups ( n =10), right coronary artery occlusion group ( n =10), and ischemia reperfusion groups with ligation of the right artery occlusion for 10, 30, 60 and 120 min respectively ( n =10 for every subgroup). The hemodynamics, His bundle electrography and epicardial electography were carried out and recorded. Results After occlusion of right coronary artery, 94.8% animals in experimental groups were found to have prolonged atrial His interval (AH) ( P

Adult ; Autopsy ; Female ; Hair ; metabolism ; Humans ; Liver ; pathology ; Thallium ; poisoning

Objective To study the diagnostic value of porphobilin staining of gastric mucus for primary pathologic duodenogastric reflux (DGR). Methods A total of 58 DGR patients diagnosed from January, 2007 to April, 2008 were recruited to the study as DGR group, and 21 healthy volunteers as control.All subjects underwent 24-hour intragastric bilirubin monitor and gastroscopy. Bilirubin absorption value of 0. 25 and median reflux time of 23.60% were taken as thresholds to differentiate low reflux group ( reflux time ＜ 23.60% ) and high reflux group (reflux time ≥23.60% ). Porphobilin staining of gastric mucosa was quantitatively analyzed. Results Deposition of porphobilin in mucosa of gastric antrum, gastric angle and gastric body in primary pathologi DGR group was significantly higher than those in healthy group (P ＜0. 05 ). The occurrence of atrophic and intestinal metaplasia of gastric antrum in high reflux group was significantly higher than that of low reflux group (P ＜ 0. 05). Deposition of porphobilin in mucosa of gastric antrum, gastric angle and gastric body in high reflux group was significantly higher than that of low reflux group (P ＜ 0. 05 ). The New Sydney system pathological scores of gastric antrum and angle of high reflux group was higher than that of low reflux group ( P ＜ 0. 05 ). The deposition of porphobilin in mucosa of gastric antrum and gastric angle was positively correlated with New Sydney system pathological scores in primary pathological DGR group (r=0.59, P=0.041 andr=0.73, P=0.038). Conclusion Porphobilin staining of mucosa in gastric antrum can reflect the severity of bile reflux, and is positively correlated with the extent of gastric mucosal lesion, which may be helpful in diagnosis of primary pathological DGR.

Amino Acid Metabolism, Inborn Errors ; blood ; diagnosis ; Humans ; Infant, Newborn ; Male

AIM: To study influence of ischemia-reperfusion(IR) on apoptosis and expression of apoptosis-related genes Fas-L, Bax and Bcl-2 of sinoatrial node(SAN) cells in rabbits in vivo. METHODS:Ninety healthy adult rabbits were divided randomly into control group, ischemia groups (I 10 min , I 30 min , I 60 min and I 120 min ) and IR groups (I 10 min R 4h , I 30 min R 4h , I 60 min R 4h and I 120 min R 4h ). IR injury model of SAN was established by occluding and loosening the start section of right coronary artery. The apoptosis of SAN cells was detected by TUNEL staining. The expression of Fas-L, Bax and Bcl-2 of SAN cells was detected by immunohistochemistry. RESULTS:①No obvious apoptosis of SAN cells was observed in control group, I 10 min and I 30 min groups. Apoptosis of different degrees in SAN cells were found in 68.3%(41/60) rabbits in I 60 min , I 120 min and 4 subgroups of IR. ②The highest expression of Fas-L and Bax was observed in I 120 min group and that of Bcl-2 was in I 60 min group. ③The highest expression of Fas-L and Bax was observed in I 60 min R 4h group. The peak level of Bcl-2 was observed in I 30 min R 4h group. ④The expression of Fas-L and Bax was significant higher in IR group than that in ischemic group at the same time point. CONCLUSION:Ischemia and IR induced apoptosis of SAN cells in rabbit in vivo . Fas-L、Bax、Bcl-2 may participate in the regulation of apoptosis and the injury during IR aggravates the apoptosis of SAN cells.

Objective To develop new methods to cultivate, retrieve and purify mouse mesenchymal stem cells (mMSCs). Methods Bone marrow was collected from 2-month-old Kunming mice by flushing femurs and tibias with complete medium of DMEM-LG. Cells were plated in a Petri dish. After 24 hours, non-adherent cells were removed by two to three washes with PBS, adherent cells were further cultured in complete medium and retrieved by trypsinisation with 0.25% trypsin for 5 min at 37 ℃. The treated adherent cells were cultivated with 3?dilution for further generations. CD11b-negative cells were retrieved from the collected adherent cells of 3rd generation by using immunomagnetic microbeads, and continued to be cultured in complete medium. After the cultured cells were retrieved, their morphology and their ability of osteoblastic differentiation and adipocytic differentiation were examined. Results Most of mMSCs from 1st generation were of shuttle shape, some of irregular shape. After treatment with magnetic microbeads and several generations, mMSCs were of spindle, star and irregular shape. These cells were of rich cytoplasma, clear nucleolus, and grew in parallel or vortex. The cultured adherent cells from the first and subsequent generations had plenty of CD11b-positive blooding-making cells. After 20-day osteoblastic induction, mMSCs differentiated into bone cells, which showed orange phosphate in extracellular matrix by Alizarin red S staining. mMSCs could differentiate into lipocytes. The size of cells increased along with fat-developing induction period. These cells showed many orange fatty follicles with O Red Oil dyeing. Conclusion Pure mMSCs can not be retrieved by either adhering method or generation cultivation method separately. The combined methods of adhering, immunomagnetic microbeads, and serial subcultivation is effective in vitro in retrieve mMSCs.

Objective To study the effect of ischemia reperfusion(IR) on electrophysiological function of sinoatrial node(SAN) in rabbits. Methods Ninety healthy adult rabbits were divided randomly into control group, ischemia groups (I) 10(I10 min), 30(I30 min), 60(I60 min) and 120 min(I120 min) and IR groups (10, 30, 60 and 120 min ischemia followed by 4 h reperfusion respectively)(I10 minR4 h, I30 minR4 h, I60 minR4 h and I120 minR4 h). There were 10 rabbits in the control group and each subgroup. IR injury model of SAN was established by occluding and loosening the start section of right coronary artery(RCA). The changes of AA interval and arrhythmia were recorded by electrocardiography and cardiac chamber electrography synchronously. Results ① There was no significant difference in AA interval between different time points in the control group. ② Sinus arrest(SA), sinus bradycardia with arrhythmia(SB), or atrial tachyarrhythmia(AT) were found in 51 rabbits (63.75%) out of 80 rabbits in I and IR groups in ischemic period. The incidence rate of arrhythmia increased in a time dependent manner. The AA intervals also increased by at least 40 ms in 54 rabbits (67.5%). ③ Sinus or atrial arrhythmia during ischemic period was found in 26 out of the 40 rabbits in IR group, but 15 returned normal after reperfusion. ④ Increased AA intervals were found in 27 out of the 40 rabbits in IR group during ischemic period. Most of them recovered to pre occlusion level within 10 min after reperfusion, but the AA intervals prolonged again in I60 minR4 h and I120 minR4 h groups as the reperfusion elongated. Conclusion ① These findings suggest that about 2/3 of the rabbit sinus node arteries may stem from right coronary artery. ② Electrophysiological changes due to ischemia of SAN resemble the electrocardiogram of sick sinoatrial node syndrome. ③ Reperfusion arrhythmia can be induced by reperfusion after a long time of ischemia.

Objective: To detect the bioavailability of 21 types of perfluorochemicals (PFCs) in rat liver and to examine the effect of protein powder. Methods: Twenty-four rats of the SD strain were randomly divided into the control group, the model group, and the protein powder group. Twenty-one types of PFCs were mixed at an equal concentration of 10 ng/mL, and rats in the model group and the protein powder group were given by oral administration of PFCs mixtures at a daily dose of 5 mL/kg. Rats in the protein powder group were given protein powder by gavage at a dose of 15 mL/kg, while animals in the model and control groups were given deionized water at doses of 15 and 20 mL/kg for 28 successive days. The PFCs contents were quantified in rat liver using ultra-high performance liquid chromatography-electrospray tandem mass spectrometry (UPLC-MS/MS), and the bioavailability was estimated. Results: There were no significant differences in rat body weight or liver/body weight ratio in the control, model and protein powder groups (P>0.05). There were no significant differences in the bioavailability of perfluoroalkylated carboxylic acid (PFCA) or sulfonate (PFSA) in the liver of female and male rats between the protein powder group and the model group (P>0.05), and the gross bioavailability of PFCA (t=-22.266, P<0.001) and PFSA (t=-34.312, P<0.001) was significantly higher in the liver of male rats than in that of female rats in the model group, and the bioavailability of PFCA and PFSA increased followed by a reduction in rat livers with the increase of carbon chain length in the model group. In the model group, the highest bioavailability was measured in perfluorododecanoic acid (PFDoA) and sodium perfluorooctylsulfonate (L-PFOS) in the female rat liver [(36.06±2.93)% and (37.11±1.73)%], and the highest bioavailability was measured in perfluorononanoic acid (PFNA) and L-PFOS in the female rat liver [(61.02±2.16)% and (87.16±3.29)%]. Conclusions The bioavailability of PFCs correlates with the carbon chain length and animal gender in rat livers, and protein powder poses no clear-cut effects on the bioavailability of 21 types of PFCs in rat livers.