| Purpose: Paraquat(PQ)is a kind of organic heterocyclic herbicide,the effective constituents of which are 1,1’-dimethyl-4,4’-bipyridine.Clinically,the acute paraquat poisoning patients caused by misusing and suicide increase day by day,with the clinical fatality rate of poisoning patients up to 85%-95%,and there is no specific antidote at present.The blood purification is the treatment measure most commonly used for the acute paraquat poisoning,while among many purification ways,the hemoperfusion(HP)is used most widely.On account of PQ has the fast metabolism in the human body,and mainly distributes in the lung,liver and other tissue and organs,with little distribution in the blood,and moreover,there is the obvious “redistribution” of PQ in the human body after the HP treatment,so that,in the clinical treatment against the acute paraquat poisoning patients,the application time,application times and other concrete application methods of HP have been debated,the exact curative effect of which also varies from each other in the relevant literatures and reports.For this purpose,by taking the beagles as the experimental subject,this research carries out the HP treatments with different schemes on it after PQ poisoning,and observes,records and compares the toxicant concentration in their blood,to explore the exact effect and meaning for eliminating the poison by carrying out the single and twice HP treatment for the acute PQ poisoning patients at the initial poisoning phase,and provide the certain reference for the clinical treatment.Method: 18 healthy mature male beagles,with average weight of(9.31±1.07)kg.Randomly divided 18 beagles into 3 groups: Group A(single HP group),Group B(twice HP group)and Group C(control group),6 beagles for each.To avoid from the uptake difference influence created by the poisoning via the gastrointestinal tract,the laboratory chooses the intravenous exposure.Dissolved the pure PQ into the normal saline as per 10mg/ml,to prepare the corresponding solution,and gave the pure PQ injection for all beagles as per the dosage of 2mg/kg,of which,calculated with 15% gastrointestinal tract absorptivity and 20% common pesticides concentration,the dosage amounts to orally take the common pesticide poisoning dosage for 46mg/ml,which reaches the severe poisoning standard.Moreover,after a series of preliminary experiments,the poisoning dosage with the concentration can guarantee to reach the severe poisoning standard,the experiment dogs will not have excessive clinical symptoms or die due to the excessive poisoning level at the same time.Made skin preparation for the fore limb of experiment dog,to inject via the vein at the outside of fore limb with disposable intravenous infusion needle.Prior to injection,fixed the infusion needle,drew the blood back to determine that the syringe needle was inside the vein vessel,and douched for twice with 2ml normal saline after injection.Gave no special treatment to the Group C,and carry out the femoral vein puncture to build the vascular access for the other two groups.In order to be closer to the treatment time practice of clinical patient,for the Group A,gave the HP treatment for 2h at the time of 4h after poisoning;for the Group B,respectively gave the HP treatments for consecutive 2h at the time of 4h and 10 h after poisoning,anticoagulation with heparin sodium wash-pipe during the HP process,both of which the extracorporeal circulation speeds were 40ml/min,and gave the protamine resist heparin after end of HP,free of any other clinical treatment.Collected and detected the toxicant concentrations in blood of beagles in every group at the 0.5h、1h、2h、4h、6h、10h、12h、24h、48h after poisoning,of which the concentrations of the Group A and Group B at 4th and 6th hour were for the bloods collected before and after the HP;the concentrations of Group B at the 10 h and 12 h respectively were for the blood collected before and after the second HP.Collected the sample with reference to American NKF-K/DOQ method,took the peripheral venous blood before getting on the machine prior to carry out the HP,and then collect the sample after HP gets off the machine,avoiding from the influence produced by the normal saline and heparin;when collecting the blood by indwelling catheter,firstly drew 10 ml blood,and then collected the sample.Centrifuge the collected in 3000r/min for 10 min,and took the supernatant liquor to put into the-20℃ refrigerator for storage and measurement.Carried out the plasma toxicant concentration detection with surface-enhanced Raman spectroscopy(SERS)methods.The used base was gold nanoparticles(Au NPs)with particle size of 50 nm,with laser power of 60 mW,as well as the acquisition time of single sample signal for 10 s.Prepared the corresponding pure PQ sample with concentration required by the standard curve,drew the corresponding standard curve,detected,calculated and recorded the PQ concentration of every experimental sample.Applied the SAS 9.2 software for the statistic analysis,represented the measurement data with ?x±s,and took the mixed effect model for the statistic analysis method,with P value <0.05 as the statistic difference.Result:(1)Three groups of experiment dogs have no statistical difference(P<0.05)in the gender and weight,while all experiment dogs did not die,free of obvious dyspnea and other clinical symptoms within 48 h.(2)Comparative results for measured values of toxicant concentrations at every time point: Carried out the difference comparison among the groups for the measured toxicant concentration of every group at every time point after poisoning by applying the mixed effect model.Prior to carried out the HP,the toxicant concentrations of every group at every time point had no statistical difference;at the 6h after poisoning,the Group A and Group B finished the first HP treatment,the toxicant concentration of which were obviously lower than that of the Group C(P<0.05),free of statistical difference in the toxicant concentrations of Group A and Group B(P>0.05);at the 10 h after poisoning,the concentrations of every group recovered to the similar level(P>0.05);at the 12 h after poisoning,the Group B finished the second HP treatment,the toxicant concentration of which was significantly lower than that of the Group A and Group C(P<0.05),free of statistical difference in the toxicant concentration of the Group A and Group C(P>0.05);at the 24 h after poisoning,the toxicant concentrations of every group recovered to the same level(P>0.05).(3)Comparative results for decreased degrees of toxicant concentrations at every time phase: Made the difference value for the toxicant concentrations measured at 4-6,10-12,2-6,2-12 and 2-24 hour after poisoning,observed the decrease condition of toxicant concentrations of every group at different time phases,and made every two difference comparison among these groups.Before and after the first HP,the toxicant concentrations of the Group A and Group B averagely decrease by 53.07% and 50.35%,much larger than the 13.40% of the Group C at the same time phase(P<0.05),free of statistical difference between the Group A and Group B(P>0.05);before and after the second HP treatment,the toxicant concentration of the Group B reduced by 67.39%,much larger than the 3.38% and 7.47% of the Group A and Group C(P<0.05),free of statistic difference between the Group A and Group C(P>0.05);from the 2h to the 24 h after poisoning,the decrease degrees of every group had no statistical difference(P>0.05).(4)Toxicokinetics comparative result of every group: Analyzed every group of data by the winnonlin5.2.1 version of pharmacokinetics software,and got every group of beagle toxicokinetics parameters.By variance analysis,every group had no statistic difference in the maximum concentration(Cmax),apparent plasma half life(t1/2),mean retention time(MRT)and area under curve(AUC)(P>0.05).Conclusion: After the poisoning,the toxicant concentrations in every group of experiment dog bodies basically reached the peak at the same time phase,free of the statistical difference in peak value.After HP,the toxicant concentrations in the experiment dog bodies significantly decreased,and then rebounded and rose in concentration in a short time,and recovered to the similar lever with the control group.From the comparison in AUC,t1/2 and MRT of three groups of beagles,it can be known that,the single or twice HP at the initial poisoning phase cannot effectively change the metabolism of PQ in the body.At the time for carrying out the HP treatment,the HP treatment at earlier time can more effectively lower the area under curve,and so that to reach the better effect in reducing the poison in the body,while the HP treatment after a long time since taking poison has the limited effect;the continuous and repeated HP treatment at the early phase probably can more timely eliminate the PQ in the blood,enabling the toxicant concentration in the blood to maintain at the low level.Analyzed the PQ metabolism trend inside the beagle body in this research,the single and twice HP treatments within 12 h after poisoning can effectively reduce the PQ concentration in the blood within in a short time after perfusion,and then rapidly recover to the same level as group(s)without perfusion;it prompts that the single or twice HP treatments at the initial poisoning phase cannot significantly change the paraquat toxicant metabolism. |
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