Combined pulsed-field gradient, shaped pulses, and product operator calculations (algorithm), two-dimensional 1 H-31 P hetero-nuclear multiple quantum coherence ( HMQC) pulse sequence was established with the aid of C language. The result showed that coherent transfer path selection could be achieved by adjusting the ratio of two gradient strength ( g1 , g2 ) . The best ratio of g1 and g2 was -5:4 . The HMQC method based on the above sequence can be used for identifying the alkyl groups coupling with phosphorous nucleus. For the different alkyl groups, the sensitivity of this method decreased in the order methyl>isopropyl>ethyl>propyl. The limit of detection was about 10 mg/L. This method can be directly used for the screening and identification of phosphorus chemical warfare agents and related compounds.

For the existing measurement methods of residual voltage which can't turn the power off at peak voltage exactly and simultaneously display waveforms, a new residual voltage detection method is put forward in this paper. First, the zero point of the power supply is detected with zero cross detection circuit and is inputted to a single-chip microcomputer in the form of pulse signal. Secend, when the zero point delays to the peak voltage, the single-chip microcomputer sends control signal to power off the relay. At last, the waveform of the residual voltage is displayed on a principal computer or oscilloscope. The experimental results show that the device designed in this paper can turn the power off at peak voltage and is able to accurately display the voltage waveform immediately after power off and the standard deviation of the residual voltage is less than 0.2 V at exactly one second and later.
Electric Power Supplies ; Equipment Design ; Microcomputers ; Signal Processing, Computer-Assisted

Objective We aimed to study the performance evaluation indicators of central venous pressure (CVP) measuring system for ICU patients in clinical trials and discuss its impact factors.Methods Ac-cording to the performance evaluation indicators of CVP measuring system based on the Delphi method,a form was created to evaluate the continuous CVP monitoring of 197 ICU patients and then the data were collected.A comparative analysis was performed to verify the factors affecting the performance of CVP measuring system.Results The performance of CVP measuring system was affected by the number of threeway switches,vasoactive drugs and positive end-expiratory pressure,the statistical value was 8.577,-6.773and 3.244.There were no statistically significant differences with respect to performance evaluation indicators of CVP measuring system among the patients with different body positions.Conclusions The performance evaluation indicators of CVP measuring sys-tem proves to be feasible and practical by clinical empirical research.Their influencing factors were dis-cussed and they offer a valuable reference for the determination of the performance of CVP measuring sys-tem in clinical practice.

AIM:To investigate the changes of connexin 43 (Cx43) via establishing a model of sympathomi-metic atrial fibrillation ( AF) .METHODS:The mongrels ( n=15) were randomly divided into control group , rapid atrial pacing (RAP) group and isoprenaline (ISO) perfusion+RAP group (ISO+RAP group).All mongrels’ hearts were taken out rapidly by median sternotomy to establish the cardiac model with Langendorff perfusion in vitro.The atrial effective re-fractory period ( AERP) and AF inducability were tested .The expression and distribution of tyrosine hydroxylase ( TH) were analyzed by immunohistochemistry .Total protein level of Cx 43 and phosphorylation of Cx 43 were determined by West-ern blot.The distribution of Cx43 were also observed by immunofluorescence staining .The cell apoptosis was analyzed by TUNEL staining.The generation of reactive oxygen species ( ROS) in the mitochondria was measured by fluorescence spec-trophotometry .RESULTS:No significant change of AERP was found between control group and RAP group , while that in ISO+RAP group was significantly decreased (P<0.05) and induced AF.Compared with control group, the expression of TH, apoptotic index and the generation of ROS increased gradually (P<0.05), while the content of Cx43 decreased grad-ually both in the total protein and the phosphorylation levels in RAP group and ISO +RAP group (P<0.05).The fluores-cence intensity of Cx43 was also attenuated and Cx43 were lateralized apparently in RAP group , while Cx43 were character-ized as punctate distribution in ISO +RAP group.CONCLUSION:Sympathetic nerves may activate autophagosome at in-tercalated discs and trigger cell apoptosis , resulting in remodeling and downregulation of Cx 43 via oxidative stress , thus having effects on mediating and maintaining AF .

Objective To investigate the alterations of connexin 43 (Cx43) expression and its distribution at different stages of myocardial infarction (MI) in rats after transplantation of allogenic mesenchymal stem cells (MSCs).Methods Wistar rats were ligated on the left anterior descending coronary artery to make MI models.They were injected with allogenic MSCs,which were induced by 5-aza and labelled by DAPI,during the second operation after 7 days of MI.In subgroups,MSCs were detected by fluorescence microscope.Cx43 expression and GJ distribu-tion were examined by immunohistochemistry after 4,8 or 12 weeks respectively.Results MSCs differentiated into cardiac muscle cell-like cells which were capable of pulsing spontaneously,expressing cTnT and forming myofilament in vitro.Transplanted MSCs can survive in MI host and upregulate Cx43 expression and normalize Cx43 distribution at ischemic zones after 4,8 and 12w.No change of Cx43 was seen at infarcted zones.Conclusion MSCs have the plasticity of differentiating into cardiac muscle cell-like cells which can continuously upregulate Cx43 expression and normalize Cx43 distribution at ischemic zones after 4,8 and 12w.

Objective To investigate the relationship between cardiac vagus nerves and changes of connexins(Cx)and intracellular gap junction(GJ)distribution pattern in superior vena cava(SVC)myosleeve in dog with atrial fibrillation(AF).Methods Twenty four hybrid dogs were divided into sham operation group(Sham group,n=8),SVC-AO fat pad removed group(RM group,n=8)and SVC-AO fat pad reserved group(RS group,n=8).In RM group and RS group,right atrial pacing was performed at a frequency of 500～650/min for 6 weeks to establish AF model.AF was induced by programmed stimulation or burst stimulation of atrial pacing.The expression and distribution of Cx40 and Cx43 in the SVC myosleeve tissue in three groups were analyzed by immunofluorescence staining.Transmission electron microscopy was used to observe the uhrastructural organization of gap junction(GJ).Results The rate of inducing sustained AF(＞ 15 min)in RS group was significantly higher than that in RM group (P ＜ 0.01).The expression of Cx40 and Cx43 in the SVC myosleeve in sham group and RS group were significantly higher than that in RM group(P ＜ 0.05).Furthermore,the expression of Cx40 and Cx43 in RS group were obviously higher than that in sham group(P ＜0.05).The ratio of end-to-end to side-to-side in RS group was lower than that in Sham group and RM group.Comparing with RM group,the channel of GJ became shorter and wider in RS group(P ＜0.05).Sarcomere was dissolved and mitochondrion showed vacuole degeneration in RS group.Conclusion The remodeling of Cx40 and Gx43 in SVC myosleeve tissue may be mediated by vagus nerves.It is conducive to the maintenance and stability of AF.However,this effect can be weakened by removing SVC-AO fat pad of canine.

Objective To investigate the effects of ischemic postconditioning on apoptosis, structural and functional changes of mitochondria induced by myocardial isehemia/reperfusion (I/R) injury of rabbits and potential mechanism. Methods Eighty healthy rabbits were divided randomly into five groups: sham operation group ( Group Sham) , ischemic reperfusion group (Group IR) , ischemic preconditioning group (Group IP) , ischemic postconditioning group (Group PC) and 5-HD plus ischemic postconditioning group (Group PC +5-HD). All rabbits in the five groups were killed 4 h after reperfusion. The hearts were quickly collected for microscopy by TUNEL. We observed ultrastructural changes of myocardium under electron microscope and examined mitochondrial membrane potential and Ca~(2+) concentration, MDA content and SOD activity of myocardial mitochondria. Results Compared with group IR, the damage of mitoehondrial ultrastrueture was milder, the apoptosis rate decreased and Ca concentration and MDA content were much lower in group IP and group PC ( P < 0. 05 ). Mitochondrial membrane potential and SOD activity of myocardial mitochondria in group IP and group PC was significantly higher than that in group IR(P<0.05). The protective effect of PC against I/R injury was partially counteracted by 5-HD .Conclusion Ischemic posteonditioning can protect the heart from I/R injury, this is supported by improvement mitochondrial ultrastructure and by decreasing apoptosis, increasing mitochondrial membrane potential and SOD activity, alleviating Ca~(2+) overload and decreasing MDA content in myocardial mitochondria. The cardio protective effects may be explained by mitochondrial ATP sensitive potassium channel.

AIM: To investigate the effects of heptanol preconditioning on the changes of structure, function and connexin 43 (Cx43) content in mitochondria in a rabbit model of myocardial isehemia-reperfusion (IR) injury. METHODS: In anesthetized open-chest rabbits, the left anterior descending artery (LAD) was occluded for 30 min and reperfused for 4 h. Sixty-four rabbits were randomly divided into 4 groups (n=16 in each group): sham operation group (sham group), ischemia-reperfusion group (IR group), ischemic preconditioning group (IP group) and heptanol preconditioning group (HT group). All rabbits in the 4 groups were killed 4 h after reperfusion. Myocardial infarct size was determined at the end of the experiment. Mitochondria was isolated by centrifugations. The ultrastructural changes of the mitochondria were observed under electronic microscope. The mitochondrial membrane potential, Ca~(2+) concentration, MDA content and SOD activity of myocardial mitochondria were also examined. The content of mitochondria Cx43 was detected by Western blotting. RESULTS: Compared to IR group, the myocardial infarct size was significantly reduced in IP (18.97%±2.80%) and HT (19.97%±3.80%) groups, the damage of mitoehondrial ultrastructure was milder (P<0.05), mitochondrial membrane potential was significantly higher and Ca~(2+) concentration was much lower (P<0.01) in IP group and HT group. No significant difference of MDA content and SOD activity in myocardial mitochondria between IR group and HT group was found. However, MDA content were much lower and SOD activity was significantly higher in IP group as compared to IR group (P<0.01). Compared to sham group, the mitochondria Cx43 expression was distinctly decreased compared to IR group (P<0.05) and no significant difference was found between IP group and HT group (P>0.05). CONCLUSION: Heptanol preconditioning protects myocardium from ischemia-reperfusion injury. The mechanism may be related to increasing in mitochondrial membrane potential, alleviating Ca~(2+) overload in myocardial mitochondria and attenuating the decrease in mitochondria Cx43 expression induced by isehemia-reperfusion.

Aim To investigate the roles of Cx43 in mitochondria and mitochondrial ATP sensitive potassium channe1(mitoK_(ATP)~+)participating in the protection for heptanol preconditioning on myocardial ischemia/reperfusion injury of rabbits.Methods In anesthetized open-chest rabbits,the left anterior descending artery(LAD)was occluded for 30 min and reperfused for 4 hrs.All rabbits were randomly divided into five groups(n=16 in each group):sham operation group(Group Sham),ischemic reperfusion group(Group IR),ischemic preconditioning group(Group IP),heptanol preconditioning group(Group HT)and 5-HD plus heptanol preconditioning group(Group HT+5-HD),All rabbits in the five groups were killed 4h after reperfusion.Myocardial infarct size was determined at the end of the experiment.The heart rate and the mean arterial pressure(MAP)were recorded and plasma CK-MB and cTnI activity were measured at baseline,the end of ischemia,and after 2 hrs and 4 hrs of reperfusion respectively.Mitochondria was isolated with different centrifugations.Ultrastructural changes of mitochondria were observed under electron microscope.The content of the mitochondria Cx43 was detected with Western blot.Results The plasma CK-MB,cTnI activity and myocardial infarct size were significantly reduced in IP(18.97±2.8)% and HT(19.97±3.8)% groups as compared to IR groups (35.67±5.8)%,(P<0.01).Compared to group IR,the damage of mitochondria in group IP and group HT were milder(P<0.01).No significant difference was found between Group IP and Group HT.Compared to sham group, the mitochondria Cx43 expression was distinctly decreased in group IR and group HT+5-HD(P<0.01)and no significant difference was found between Group IP and Group HT.Conclusions Heptanol preconditioning can protect the heart from I/R injury by improving mitochondrial ultrastructure and by attenuating the decrease of mitochondria Cx43 expression induced by I/R.The mitochondrial Cx43 expression may be concerned with depending on mito K_(ATP)~+.

BACKGROUND:Cell transplantation can repair damaged myocardial tissue.However,whether transplaned cells and host cells formed an effective electricity and mechanical couple or whether reconstruction of connexin (Cx) and arrhythmia formed,are still unclear.OBJECTIVE:It is hypothesized that arrhythmia can be treated by changing Cx levels and intervening abnormal GJ channel.Moreover,to explore the effects of bone marrow mesenchyma stem cells (MSCs) on the expression of Cx43 and Cx45 in rata with myocardial infarction.DESIGN,TIME AND SETTING:The randomized controlled animal study was performed at the Experimental Center,Guangxi Medical University from January 2008 to May 2009.MATERIALS:A total of 180 Wistar rats were randomly divided into four groups:normal control,sham operation,myocardial infarction,and MSCs,with 45 animals in each group.Each group was then divided into 3 subgroups (n=15) according to 4 weeks,8 weeks and 12 weeks post-transplantation.Additional 20 healthy,Wistar rats,aged 1 month,were selected to harvest MSCs.METHODS:The third passage of MSCs was induced by 5-aza like cardiomyocytes for 4 weeks,labeled with DAPI at 2 hours before transplantation.Models of acute myocardial infarction were established in all groups except sham operation group.At day 7 after model preparation,2×10~(10) /L MSCs were infused into the edge and center of myocardial infarcted region by multipoint injection.Rats in the myocardial infarction group were subjected to an equal volume of saline as wall as those in the normal control and sham operation groups.MAIN OUTCOME MEASURES:The mRNA expressions of Cx43,Cx45 were assayed by fluorescence quantitative PCR.RESULTS:The mRNA expression of Cx43 among each groups had no difference at weeks 4,8 and 12 after intervention in the normal areas.Compared to the normal areas,Cx43 mRNA reduced significantly at ischamic zone in the myocardial infarction group and MSCs group (P＜0.01),with notably increased of Cx45 mRNA expression (P＜0.01).Compared to myocardial infarction group,Cx43 mRNA expression was statistically higher in the MSCs group at the same points (P ＜ 0.01),and the Cx45 mRNA dramatically declined (P ＜ 0.01).CONCLUSION:Acute myocardial infarction reduces the mRNA expression of Cx43 and increases the Cx45 mRNA expression.The exogenous cells transplantation can upturn the mRNA expression of Cx43 in the border-zone of the infarcted area,and down-regulate the Cx45 mRNA expression in the border-zone of the infarcted area.