Background: Warm ischemia jeopardizes graft quality and recipient survival in donation after cardiac death(DCD) transplantation. Currently, there is no system to objectively evaluate the liver quality from DCD. The pr...Background: Warm ischemia jeopardizes graft quality and recipient survival in donation after cardiac death(DCD) transplantation. Currently, there is no system to objectively evaluate the liver quality from DCD. The present study tried to use energy metabolites to evaluate the donor liver quality. Methods: We divided 195 Sprague-Dawley rats into five groups: the control( n = 39), warm ischemic time(WIT) 15 min( n = 39), WIT 30 min( n = 39), WIT 45 min( n = 39), and WIT 60 min( n = 39) groups. Three rats from each group were randomly selected for pretransplant histologic evaluation of warm ischemiarelated damage. The remaining 36 rats were randomly divided into donors and recipients of 18 liver transplantations, and were subjected to postoperative liver function and survival analyses. Between cardiac arrest and cold storage, liver energy metabolites including glucose, lactate, pyruvate, and glycerol were measured by microdialysis. The lactate to pyruvate ratio(LPR) was calculated. Results: The changes in preoperative pathology with warm ischemia were inconspicuous, but the trends in postoperative pathology and aminotransferase levels were consistent with preoperative energy metabolite measurements. The 30-day survival rates of the control and WIT 15, 30, 45, and 60 min groups were 100%, 81.82%, 76.92%, 58.33%, and 25.00%, respectively. The areas under the receiver operating characteristic curves of glucose, lactate, glycerol, and LPR were 0.87, 0.88, 0.88, and 0.92, respectively. Conclusion: Glucose, lactate, glycerol, and LPR are predictors of graft quality and survival outcomes in DCD transplantation.展开更多
Microdialysis is a technique used to measure the unbound antibiotic concentration in the interstitial spaces, the target site of action. In vitro recovery studies are essential to calibrating the microdialysis system ...Microdialysis is a technique used to measure the unbound antibiotic concentration in the interstitial spaces, the target site of action. In vitro recovery studies are essential to calibrating the microdialysis system for in vivo studies. The effect of a combination of antibiotics on recovery into microdialysate requires investigation. In vitro microdialysis recovery studies were conducted on a combination of vancomycin and tobramycin, in a simulated in vivo model. Comparison was made between recoveries for three different concentrations and three different perfusate flow rates. The overall relative recovery for vancomycin was lower than that of tobramycin. For tobramycin, a concentration of 20μg/mL and flow rate of 1.0μL/min had the best recovery. A concentration of 5.0μg/mL and flow rate of 1.0μL/min yielded maximal recovery for vancomycin. Large molecular size and higher protein binding resulted in lower relative recoveries for vancomycin. Perfusate flow rates and drug concentrations affected the relative recovery when a combination of vancomycin and tobramycin was tested. Low perfusate flow rates were associated with higher recovery rates. For combination antibiotic measurement which includes agents that are highly protein bound, in vitro studies performed prior to in vivo studies may ensure the reliable measurement of unbound concentrations.展开更多
Background: The brain bioavailability of novel small molecules developed to address central nervous system disease is classically documented through ex vivo or in vivo analyses conducted in rodent models. Data acquire...Background: The brain bioavailability of novel small molecules developed to address central nervous system disease is classically documented through ex vivo or in vivo analyses conducted in rodent models. Data acquired in rodent models are, however,not easily transferrable to human as the pharmacokinetic and pharmacodynamics profiles of the species are quite different.Methods: Using drugs selected for their differential transport across the blood-brain barrier, we here demonstrate the feasibility of brain microdialysis in normal vigil macaque monkey by measuring brain extracellular fluid bioavailability of carbamazepine, digoxin, oxycodone, and quinidine.Results: All drugs, but digoxin, were found in dialysate samples. Drugs that are substrate of P-glycoprotein show a difference of bioavailability or brain pharmacokinetic parameters between rodents and primates.Conclusion: Data suggest that brain microdialysis in vigil macaque monkey, the species of choice for classic pharmacokinetic/pharmacodynamics studies could help predicting human brain bioavailability of a small molecule depending on the protein involved in the efflux transport from the brain.展开更多
The purpose of the study was to evaluate the effects of corticosteroids on histamine release and to compare their potency with the MacKenzie classification based on their vasoconstrictor effects. Thanks to ex Vivo cut...The purpose of the study was to evaluate the effects of corticosteroids on histamine release and to compare their potency with the MacKenzie classification based on their vasoconstrictor effects. Thanks to ex Vivo cutaneous microdialysis, we studied histamine-induced release over a period of time on excised abdominal skin from women. Eight corticosteroids were topically applied with occlusive dressing onto the skin, above probes, before anti-IgE injection. Histamine levels were assessed by an EIA method. In order to compare the different corticosteroids, AUC was calculated allowing an estimation of the amount of released histamine for 60 min of ex vivo cutaneous microdialysis. Diflucortolone 0.1% and micronized betamethasone dipropionate 0.05% are considered as corticosteroids with high potency in MacKenzie classification. Betamethasone dipropionate associated with propylene glycol 0.05%, belongs to a stronger class in Mackenzie classification. Our results showed that the decrease in histamine release was more important with difluocortolone than with both of these corticosteroids. Therefore there was no correlation between the vasoconstrictor potency of topical corticosteroids and their ability to inhibit histamine release.展开更多
The traditional Chinese medicine tripterygium glycosides(TPG)is used clinically to treat some Rheumatism,Eczema,immunosuppression and tumor,with the activities of hypnosis,antipyretic,analgesic,antiinflammatory,allerg...The traditional Chinese medicine tripterygium glycosides(TPG)is used clinically to treat some Rheumatism,Eczema,immunosuppression and tumor,with the activities of hypnosis,antipyretic,analgesic,antiinflammatory,allergy and antitumor.However TPG has low water solubility and low skin permeability,so its clinical use is limited.Transdermal delivery systems can provide a controlled drug release rate that can keep constant concentrations of drug in the plasma for up to multiple days,improved patient compliance,and the possibility ofreducing the rate and severity of side effects.In this study,a fast and sensitive technique skin-blood two sites synchronous microdialysis coupled with LC-MS was used to study the pharmacokinetic parameter of three different formulations(TPG nanoemulsion,TPG nanoemulsion based gels and TPG gel).Creating a multilayer model,use the model to simulate the three formulations dynamics in transdermal-drug delivery system.The experiment results showed that the TPG nanoemulsion,TPG nanoemulsion based gels can significantly raise the drug concentrations in skin more than that of TPG gels.The numerical simulation results indicating that TPG gel and TPG nanoemulsion are close to practical measurements,only in the concentration increase phase the numerical simulation result has some difference with the experimental results.TPG nanoemulsion based gels have significant difference with the experimental results,both in concentration increase stage and concentration decreasing stage,but its trend was same.The study shows that the skin-blood synchronous microdialysis technique provided a new method for the pharmacokinetics study of nanocarriers transdermal delivery systems.In addition,the microdialysis technique combined with mathematical modeling provides a very good platform for the further study of transdermal delivery system.展开更多
S100B protein is released by astrocytes into the brain extracellular fluid following acute brain injury and elevated levels in CSF and serum have been shown to correlate with patient outcome following traumatic brain ...S100B protein is released by astrocytes into the brain extracellular fluid following acute brain injury and elevated levels in CSF and serum have been shown to correlate with patient outcome following traumatic brain injury. A prospective study of brain extracellular fluid (ECF) and serum S100B levels in 12 patients with severe head injury (GCS ≤ 8) was undertaken using intracerebral microdialysis to investigate whether a correlation with ECF S100B and outcome could be confirmed. Patient outcomes were assessed at 6 months using the Glasgow Outcome Scale (GOS) and divided into two outcome groups: group A, 8 survivors with either a good recovery or moderate disability (GOS scores of 4 or 5);and group B, 4 patients who died (GOS 1). Peak serum levels of S100B were significantly greater in group B (mean 6.03 ng/ml) compared with group A (mean 0.73 ng/ml) (P = 0.009). Group A had a mean peak S100B in the extracellular compartment of 186 ng/ml compared to 150 ng/ml in group B. There was no significant difference between the mean peak brain ECF S100B concentrations for the 2 outcome groups (P = 0.932). We confirm that intracerebral microdialysis can be used to sample S100B concentrations from brain extracellular fluid and our results suggest that the ECF S100B levels were variable and that there was no significant difference between the good outcome and poor outcome groups. In contrast, the serum levels of S100B of patients with a poor outcome were significantly higher than those with a good outcome.展开更多
In Parkinson’s disease (PD), dopaminergic neurons reduce the regulation of glutamatergic (glutamate-Glu) input from the cortex to neostriatum (caudate and putamen nuclei) consequently leading to a hyperactivity of gl...In Parkinson’s disease (PD), dopaminergic neurons reduce the regulation of glutamatergic (glutamate-Glu) input from the cortex to neostriatum (caudate and putamen nuclei) consequently leading to a hyperactivity of globus pallidus internae (GPi) neurons that release gamma-amino-butyric acid (GABA) into the thalamic ventrolateral (VL) nucleus. The objective of the present experiment was to measure changes in GABA and Glu in the caudate and the thalamus of 2 patients during the application of electrical stimuli following either a pallidotomy or a thalamotomy. Proper insertion of the electrode was tested by applying high frequency electrical pulses (HFEP). During these procedures, we obtained neurochemical information placing cerebral (CMD) microdialysis probes in caudate nucleus and VL nucleus of ipsi- and contra-lateral thalamus. In VL thalamus, extracellular GABA decreased during HFEP, tending to reach previous levels once HFEP was finalized. Following the pallido- or thalamotomy GABA decreased again. Similarly, in the contralateral VL thalamus, extracellular GABA levels showed a similar but less pronounced profile but did not show any decrement after the lesion. Caudate Glu decreases when HFEP is applied to the GPi and recovers to previous levels after HFEP, but did not decrease again after lesion (GPi-tomy), instead it continued to rise. These results suggest that HFEP exerts a similar but reversible biochemical effect as thermopallido- or thermothalamotomy on GABA extracellular concentration in the ipsilateral VL thalamus. We also observe a distant effect of HFEP, but not of thermolesion, on contralateral thalamic GABA and ipsilateral caudate Glu.展开更多
Neurosurgery for psychiatric disorders, notably for obsessive-compulsive disorder (OCD), was initiated in Venezuela in the decade of 1970, and consisted since that time in the classic stereotactic anterior cingulotomy...Neurosurgery for psychiatric disorders, notably for obsessive-compulsive disorder (OCD), was initiated in Venezuela in the decade of 1970, and consisted since that time in the classic stereotactic anterior cingulotomy. In order to know further about the physiopathology of this disorder, we performed intracerebral microdialysis in 2 patients who were operated on. The aim was to measure changes in extracellular neurotransmitters within the basal ganglia. The microdialysis probes were stereotactically placed in the right caudate nucleus and in the dorsomedial nucleus of the right thalamus. The microdialysis was done before the left cingulotomy, during the pause and after the right cingulotomy. Glutamate and gamma-aminobutyric acid (GABA) changes were similar in the caudate nucleus of both patients, whereas in the dorsomedial nucleus the changes were opposite among the 2 patients. Although this study does not bring enough data to explain such differences yet, the existence of dynamic changes in the neurochemistry of the basal ganglia during cingulotomy shows that intracerebral microdialysis can help in the understanding of the pathophysiology of OCD and eventually in the design of new surgeries with better results.展开更多
Clinical microdialysis allows a discrete volume of the brain to be sampled for neurochemical analysis of neurotransmitters, metabolites, biomarkers, and drugs. The technique can be safely used in humans intraoperative...Clinical microdialysis allows a discrete volume of the brain to be sampled for neurochemical analysis of neurotransmitters, metabolites, biomarkers, and drugs. The technique can be safely used in humans intraoperatively, in the intensive care unit, and in ambulatory settings. Microdialysis probes, micropumps, and analytical equipment are commercially available and have been used extensively for neurochemical monitoring in traumatic brain injury, stroke, and subarachnoid hemorrhage. There has been very limited use of microdialysis in neuro-oncology, but this technique has great promise in the study of the basic neurochemistry of brain tumors, alterations in neurochemistry in response to therapy, and the pharmacokinetics of chemotherapeutic agents. Microdialysis probes may also be used to deliver drugs while simultaneously permitting monitoring of neurochemical changes induced by this therapy.展开更多
A new chemically modified electrode(CME) immobilized on the surface of multi-wall carbon nanotubes functionalized with carboxylic groups was fabricated. The results indicate that the CME exhibits efficiently electroca...A new chemically modified electrode(CME) immobilized on the surface of multi-wall carbon nanotubes functionalized with carboxylic groups was fabricated. The results indicate that the CME exhibits efficiently electrocatalytic oxidation of 6-mercaptopurine(6-MP). The CME can be used as the working electrode in the liquid chromatography for the determination of 6-MP. The peak current of 6-MP is linearly changed with its concentration ranging from 4.0×10 -7 to 1.0×10 -4 mol/L with the calculated detection limit (S/N=3) of 2.0×10 -7 mol/L. Coupled with microdialysis sampling, the method has been successfully applied to assessing the content of 6-MP in rat blood.展开更多
Some natural products,such as traditional Chinese medicines(TCMs),contain compounds with anticancer activity and have attracted a great interest in recent years as alternative anticancer therapies. A quick and conveni...Some natural products,such as traditional Chinese medicines(TCMs),contain compounds with anticancer activity and have attracted a great interest in recent years as alternative anticancer therapies. A quick and convenient assay for screening antimicrotubule compounds in which in vitro microdialysis/high-performance liquid chromatography (HPLC) is used to monitor the binding of the compounds extracted from TCM Taxus cuspidata Siebold & Zucc(Taxus) to microtubules is reported. It was observed that the extract of Taxus contains at least five compounds which have affinity interaction with microtubules by biological fingerprinting analysis,and they were identified as the taxoids of taxol,baccatin Ⅲ,10-deacetylbaccatin Ⅲ(10-DAB),cephalomannine and 7-epi-10-deacetyltaxol (7-epi-10-DAT) based on the comparison of their high-performance liquid chromatographic/mass spectrometric and UV spectra with those of the standard samples,both assembly-promoting and disassembly-inhibiting characteristics of those compounds were evaluated. It was observed that baccatin Ⅲ and 10-DAB bound to microtubules and the binding degrees were influenced by GTP. Competitive binding behavior of taxol with other four taxoids to microtubules was also investigated.展开更多
Objective To determine dopamine and its metabolites during in vivo cerebral microdialysis by routine high performance liquid chromatography with electrochemical detection.Methods Microdialysis probes were placed into ...Objective To determine dopamine and its metabolites during in vivo cerebral microdialysis by routine high performance liquid chromatography with electrochemical detection.Methods Microdialysis probes were placed into the right striatum of Wistar rat brains and perfused with Ringer's solution at a rate of 1.5 μL/min.A reverse phase HPLC with electrochemistry was used to assay DA,DOPAC,and HVA after cerebral microdialysates were collected every 20 minutes from awake and freely moving rats.In order to identify the reliability of this method,its selectivity,linear range,precision and accuracy were tested and the contents of DA,DOPAC,and HVA in rat microdialysates were determined.Results The standard curve was in good linear at the concentration ranging from 74 nmol/L to 1.5 μmol/L for DOPAC(r2= 0.9996),from 66 nmol/L to 1.3 μmol/L for DA(r2=1.0000)and from 69 nmol/L to 1.4 μmol/L for HVA(r2=0.9992).The recovery of DOPAC(0.30,0.77,1.49 μmol/L),DA(0.26,0.69,1.32 μmol/L),and HVA(0.27,0.71,1.37 μmol/L)was 82.00±1.70%,104.00±4.00%,98.70±3.10%;92.30±1.50%,105.30±2.30%,108.00±2.00%;80.00±7.80%,107.69±8.00%,and 108.66±3.10%,respectively at each concentration.Their intra-day RSD was 3.3%,3.4%,and 2.5%,and inter-day RSD was 4.2%,2.3%,and 5.6%,respectively.The mean extracellular concentrations of DOPAC,DA,and HVA in rat brain microdialysates were 10.7,2.4,and 9.2 μmol/L(n=6),respectively.Conclusion The findings of our study suggested that the simple,accurate and stable method can be applied to basic researches of diseases related to monoamines neurotransmitters by cerebral microdialysis in rats.展开更多
The aim of this study was to investigate the effect of 30 min forebrain ischemia,followed by120 min reperfusion on extracellular fluid(ECF)levels of dopamine(DA),norepinephrine(NE),serotonin(5-HT)and their metabolites...The aim of this study was to investigate the effect of 30 min forebrain ischemia,followed by120 min reperfusion on extracellular fluid(ECF)levels of dopamine(DA),norepinephrine(NE),serotonin(5-HT)and their metabolites,homovanillic acid(HVA)and 5-hydroxyindoleacetic acid(5-HIAA)in the striatum of gerbils,so as to obtain furtherinformation on the mechanism of Radix Salviae Miltiorrhizae(RSM)-inducedneuroprotection.Microdialysis was used to sample the extracellular space.Dialysate wasmeasured by high performance liquid chromatography with electrochemical detector(HPLC-ED).ECF DA,NE levels increased from basal levels by 282,227 and 221 folds,by9.14,8.51 and 8.25 folds,respectively for the three ischemic duration(0-10;11-20;21-30min).ECF DA,NE,5-HT levels in the RSM-treated group were significantly decreased ascompared with those in the control group during ischemia(P【0.01).The results suggestedthat monoamine neurotransmitters were involved in ischemic neuron damage directly orindirectly;and that RSM plays a protective role during cerebral ischemia by attenuating thedysfunctions of monoamine neurotransmitters.展开更多
To investigate the effect on central nervous transmission of toosendanin (TSN), a presynaptic blocker, rat striatum was perfused in vivo with a TSN-containing artificial cere-brospinal fluid (ACSF) and the level of do...To investigate the effect on central nervous transmission of toosendanin (TSN), a presynaptic blocker, rat striatum was perfused in vivo with a TSN-containing artificial cere-brospinal fluid (ACSF) and the level of dopamine (DA) as well as related metabolites in the collected dialysates has been determined by a microbore HPLC with electrochemical detection (mi-crobore HPLC-ECD). The results are as follows: ( i ) TSN induced a biphasic change of DA from its basal level;( ii ) the basal contents of two metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) increased in turn and stayed at a higher level than basal control for a long period. The basal level of 5-hydroxyindoleacetic acid (5-HIAA), a metabolite of 5-hydroxytryptamine(5-HT), had a change similar to that of HVA; (iii) after per-fusion with TSN-containing ACSF, high K+-evoked DA release was inhibited. These results show that TSN does not selectively affect acetylcholine (ACh) release, but probably acts on a common展开更多
A method has been established to study the competing binding of metal ions with protein by a combined technique of microdialysis with high performance liquid chromatography (HPLC). Ni2+, Cd2+, Zn2+, Cu2+ and human ser...A method has been established to study the competing binding of metal ions with protein by a combined technique of microdialysis with high performance liquid chromatography (HPLC). Ni2+, Cd2+, Zn2+, Cu2+ and human serum albumin (HSA) were chosen as model metal ions and protein. The experimental results show that Ni2+ and Cu2+ share a common primary binding site on HSA, and Zn2+ and Cd2+ share a different common primary binding site from them, but there is a common multi-metal binding site for all of those four metal ions. This method show advantages of fast sampling, easily to be operated and especially to be useful when ideal spectroscopic probes are not available for the study of interaction between protein and metal ions.展开更多
A new method to determine the interaction between drug and protein has been developed by utilizing the technique of microdialysis sampling with the ketoprofen and the human serum albumin (HSA) as the model of drug and...A new method to determine the interaction between drug and protein has been developed by utilizing the technique of microdialysis sampling with the ketoprofen and the human serum albumin (HSA) as the model of drug and protein.Two kinds of binding sites of HSA to ketoprofen have been observed.The binding constants and number of binding sites obtained by the Scatchard equation are 0.799,3.18×106 mol-1 L and 2.15,2.01×105 mol-1 L,respectively The displacement binding of drugs to HSA has also been studied.The strong displacement of competitive binding of ibuprofen with ketoprofen to HSA was observed,which means that the primary binding site of HSA to ketoprofen and that to ibuprofen are the same.However,only a weaker displacement of warfarin for the association of ketoprofen with HSA was observed,which may suggest that the primary binding site of HSA to ketoprofen is different from that to warfarin.Such a displacement effect for competitive binding of drugs to HSA was explained by the displacement model展开更多
This paper describes the development of a monitoring system capable of detecting the concentration of magnesium ions(Mg^(2+)) released during the degradation of magnesium implants. The system consists of a microdialys...This paper describes the development of a monitoring system capable of detecting the concentration of magnesium ions(Mg^(2+)) released during the degradation of magnesium implants. The system consists of a microdialysis probe that samples fluid adjacent to the implant and a catalytic biosensor specific to Mg^(2+)ions. The biosensor was fabricated on a cotton fabric platform, in which a mixture of glycerol kinase and glycerol-3-phosphate oxidase enzymes was immobilized on the fabric device via a simple matrix entrapment technique of the cotton fibers. Pure magnesium was used as the implant material. Subsequently, the concentration of ions released from the degradation of the magnesium specimen in Ringer's solution was evaluated using cyclic voltammetry technique. The device demonstrated a pseudo-linear response from 0.005 to 0.1 mmol L^(-1) with a slope of 67.48 μA mmol^(-1) L. Detectable interfering species were lesser than 1%indicating a high selectivity of the fabric device. Furthermore,the device requires only 3 μL of fluid sample to complete the measurement compared to spectroscopic method(±50 μL),hence providing a higher temporal resolution and reduced sampling time. The system could potentially provide a real time assessment of the degradation behavior, a new studied aspect in biodegradable metals research.展开更多
Objective To conduct a comparative study on the brain pharmacokinetics of seven ingredients(i.e.senkyunolide A,ferulic acid,formononetin,calycosin,ononin,calycosin-O-β-D-glucopyranoside,and paeoniflorin),which were t...Objective To conduct a comparative study on the brain pharmacokinetics of seven ingredients(i.e.senkyunolide A,ferulic acid,formononetin,calycosin,ononin,calycosin-O-β-D-glucopyranoside,and paeoniflorin),which were the compounds of Buyang Huanwu Decoction(BHD),in normal and cerebral ischemia rats administrated intragastrically with BHD.Methods The samples of normal and permanent middle cerebral artery occlusion(pMCAO)rats were collected by using brain microdialysis technique.The concentrations of seven ingredients were determined by the HPLC-MS/MS method.After the BHD were administrated intragastrically to the rats for seven consecutive days,brain microdialysis probes were inserted into the hippocampus of rats,and then the brain microdialysates were collected at 20 min time intervals for 5 h.The separation of the seven ingredients and internal standard(IS)was carried out on an ACQUITY UPLC BEH C18(2.1 mm×100 mm,1.7μm)chromatographic column,using a mobile phase consisting of acetonitrile(containing 0.1%formic acid)and water(containing 0.1%formic acid)for gradient elution within 13 min.The ionization was conducted using an ESI source in positive ion mode.Multiple reaction monitoring mode was used for quantification of ingredients in BHD.Results Linearity,accuracy,precision,matrix effect and stability of LC-MS/MS method were all satisfactory,successfully applied to compare the pharmacokinetics of the analytes between normal and model rats after intragastric administration of BHD.Compared with the normal group,the model group after the administration of the BHD showed that T1/2 of formononetin and ononin were longer,and except for calycosin-O-β-D-glucopyranoside(P<0.01),there was no significant difference between the normal group and the model group.The C_(max) of senkyunolide A and calycosin of model group were increased,while the T_(max) of senkyunolide A was decreased,and except for the T_(max) of PF,the differences between the two groups were statistically significant(P<0.01).Conclusion The LC-MS/MS method combined with microdialysis was successfully applied to the comparative study of brain pharmacokinetics of seven ingredients in BHD.After intragastric administration of BHD,there were differences in the pharmacokinetics of seven ingredients in the brain hippocampus between normal rats and model rats,probably related to the characteristics of the ingredients and the effects of cerebral ischemia on the absorption and distribution of the ingredients.展开更多
基金supported by a grant from the Health Public Welfare Research Special Cooperation Project(No.03047)
文摘Background: Warm ischemia jeopardizes graft quality and recipient survival in donation after cardiac death(DCD) transplantation. Currently, there is no system to objectively evaluate the liver quality from DCD. The present study tried to use energy metabolites to evaluate the donor liver quality. Methods: We divided 195 Sprague-Dawley rats into five groups: the control( n = 39), warm ischemic time(WIT) 15 min( n = 39), WIT 30 min( n = 39), WIT 45 min( n = 39), and WIT 60 min( n = 39) groups. Three rats from each group were randomly selected for pretransplant histologic evaluation of warm ischemiarelated damage. The remaining 36 rats were randomly divided into donors and recipients of 18 liver transplantations, and were subjected to postoperative liver function and survival analyses. Between cardiac arrest and cold storage, liver energy metabolites including glucose, lactate, pyruvate, and glycerol were measured by microdialysis. The lactate to pyruvate ratio(LPR) was calculated. Results: The changes in preoperative pathology with warm ischemia were inconspicuous, but the trends in postoperative pathology and aminotransferase levels were consistent with preoperative energy metabolite measurements. The 30-day survival rates of the control and WIT 15, 30, 45, and 60 min groups were 100%, 81.82%, 76.92%, 58.33%, and 25.00%, respectively. The areas under the receiver operating characteristic curves of glucose, lactate, glycerol, and LPR were 0.87, 0.88, 0.88, and 0.92, respectively. Conclusion: Glucose, lactate, glycerol, and LPR are predictors of graft quality and survival outcomes in DCD transplantation.
基金funded by the TPCH foundation grant (MS201140)the RBWH foundation grant 2012+1 种基金funding from the Australian National Health and Medical Research Council for a Centre of Research Excellence (APP1099452)funded in part by a Practitioner Fellowship (APP1117065) from the National Health and Medical Research Council of Australia
文摘Microdialysis is a technique used to measure the unbound antibiotic concentration in the interstitial spaces, the target site of action. In vitro recovery studies are essential to calibrating the microdialysis system for in vivo studies. The effect of a combination of antibiotics on recovery into microdialysate requires investigation. In vitro microdialysis recovery studies were conducted on a combination of vancomycin and tobramycin, in a simulated in vivo model. Comparison was made between recoveries for three different concentrations and three different perfusate flow rates. The overall relative recovery for vancomycin was lower than that of tobramycin. For tobramycin, a concentration of 20μg/mL and flow rate of 1.0μL/min had the best recovery. A concentration of 5.0μg/mL and flow rate of 1.0μL/min yielded maximal recovery for vancomycin. Large molecular size and higher protein binding resulted in lower relative recoveries for vancomycin. Perfusate flow rates and drug concentrations affected the relative recovery when a combination of vancomycin and tobramycin was tested. Low perfusate flow rates were associated with higher recovery rates. For combination antibiotic measurement which includes agents that are highly protein bound, in vitro studies performed prior to in vivo studies may ensure the reliable measurement of unbound concentrations.
文摘Background: The brain bioavailability of novel small molecules developed to address central nervous system disease is classically documented through ex vivo or in vivo analyses conducted in rodent models. Data acquired in rodent models are, however,not easily transferrable to human as the pharmacokinetic and pharmacodynamics profiles of the species are quite different.Methods: Using drugs selected for their differential transport across the blood-brain barrier, we here demonstrate the feasibility of brain microdialysis in normal vigil macaque monkey by measuring brain extracellular fluid bioavailability of carbamazepine, digoxin, oxycodone, and quinidine.Results: All drugs, but digoxin, were found in dialysate samples. Drugs that are substrate of P-glycoprotein show a difference of bioavailability or brain pharmacokinetic parameters between rodents and primates.Conclusion: Data suggest that brain microdialysis in vigil macaque monkey, the species of choice for classic pharmacokinetic/pharmacodynamics studies could help predicting human brain bioavailability of a small molecule depending on the protein involved in the efflux transport from the brain.
文摘The purpose of the study was to evaluate the effects of corticosteroids on histamine release and to compare their potency with the MacKenzie classification based on their vasoconstrictor effects. Thanks to ex Vivo cutaneous microdialysis, we studied histamine-induced release over a period of time on excised abdominal skin from women. Eight corticosteroids were topically applied with occlusive dressing onto the skin, above probes, before anti-IgE injection. Histamine levels were assessed by an EIA method. In order to compare the different corticosteroids, AUC was calculated allowing an estimation of the amount of released histamine for 60 min of ex vivo cutaneous microdialysis. Diflucortolone 0.1% and micronized betamethasone dipropionate 0.05% are considered as corticosteroids with high potency in MacKenzie classification. Betamethasone dipropionate associated with propylene glycol 0.05%, belongs to a stronger class in Mackenzie classification. Our results showed that the decrease in histamine release was more important with difluocortolone than with both of these corticosteroids. Therefore there was no correlation between the vasoconstrictor potency of topical corticosteroids and their ability to inhibit histamine release.
基金The project supported by National Natural Science Foundation of China(81573613,81373896)the Major Program for the Fundamental Research of Shanghai Committee of Science and Technology(14JC1491300)Open Fund of State Key Laboratory of Natural Medicines(SKLNMKF201612)
文摘The traditional Chinese medicine tripterygium glycosides(TPG)is used clinically to treat some Rheumatism,Eczema,immunosuppression and tumor,with the activities of hypnosis,antipyretic,analgesic,antiinflammatory,allergy and antitumor.However TPG has low water solubility and low skin permeability,so its clinical use is limited.Transdermal delivery systems can provide a controlled drug release rate that can keep constant concentrations of drug in the plasma for up to multiple days,improved patient compliance,and the possibility ofreducing the rate and severity of side effects.In this study,a fast and sensitive technique skin-blood two sites synchronous microdialysis coupled with LC-MS was used to study the pharmacokinetic parameter of three different formulations(TPG nanoemulsion,TPG nanoemulsion based gels and TPG gel).Creating a multilayer model,use the model to simulate the three formulations dynamics in transdermal-drug delivery system.The experiment results showed that the TPG nanoemulsion,TPG nanoemulsion based gels can significantly raise the drug concentrations in skin more than that of TPG gels.The numerical simulation results indicating that TPG gel and TPG nanoemulsion are close to practical measurements,only in the concentration increase phase the numerical simulation result has some difference with the experimental results.TPG nanoemulsion based gels have significant difference with the experimental results,both in concentration increase stage and concentration decreasing stage,but its trend was same.The study shows that the skin-blood synchronous microdialysis technique provided a new method for the pharmacokinetics study of nanocarriers transdermal delivery systems.In addition,the microdialysis technique combined with mathematical modeling provides a very good platform for the further study of transdermal delivery system.
文摘S100B protein is released by astrocytes into the brain extracellular fluid following acute brain injury and elevated levels in CSF and serum have been shown to correlate with patient outcome following traumatic brain injury. A prospective study of brain extracellular fluid (ECF) and serum S100B levels in 12 patients with severe head injury (GCS ≤ 8) was undertaken using intracerebral microdialysis to investigate whether a correlation with ECF S100B and outcome could be confirmed. Patient outcomes were assessed at 6 months using the Glasgow Outcome Scale (GOS) and divided into two outcome groups: group A, 8 survivors with either a good recovery or moderate disability (GOS scores of 4 or 5);and group B, 4 patients who died (GOS 1). Peak serum levels of S100B were significantly greater in group B (mean 6.03 ng/ml) compared with group A (mean 0.73 ng/ml) (P = 0.009). Group A had a mean peak S100B in the extracellular compartment of 186 ng/ml compared to 150 ng/ml in group B. There was no significant difference between the mean peak brain ECF S100B concentrations for the 2 outcome groups (P = 0.932). We confirm that intracerebral microdialysis can be used to sample S100B concentrations from brain extracellular fluid and our results suggest that the ECF S100B levels were variable and that there was no significant difference between the good outcome and poor outcome groups. In contrast, the serum levels of S100B of patients with a poor outcome were significantly higher than those with a good outcome.
文摘In Parkinson’s disease (PD), dopaminergic neurons reduce the regulation of glutamatergic (glutamate-Glu) input from the cortex to neostriatum (caudate and putamen nuclei) consequently leading to a hyperactivity of globus pallidus internae (GPi) neurons that release gamma-amino-butyric acid (GABA) into the thalamic ventrolateral (VL) nucleus. The objective of the present experiment was to measure changes in GABA and Glu in the caudate and the thalamus of 2 patients during the application of electrical stimuli following either a pallidotomy or a thalamotomy. Proper insertion of the electrode was tested by applying high frequency electrical pulses (HFEP). During these procedures, we obtained neurochemical information placing cerebral (CMD) microdialysis probes in caudate nucleus and VL nucleus of ipsi- and contra-lateral thalamus. In VL thalamus, extracellular GABA decreased during HFEP, tending to reach previous levels once HFEP was finalized. Following the pallido- or thalamotomy GABA decreased again. Similarly, in the contralateral VL thalamus, extracellular GABA levels showed a similar but less pronounced profile but did not show any decrement after the lesion. Caudate Glu decreases when HFEP is applied to the GPi and recovers to previous levels after HFEP, but did not decrease again after lesion (GPi-tomy), instead it continued to rise. These results suggest that HFEP exerts a similar but reversible biochemical effect as thermopallido- or thermothalamotomy on GABA extracellular concentration in the ipsilateral VL thalamus. We also observe a distant effect of HFEP, but not of thermolesion, on contralateral thalamic GABA and ipsilateral caudate Glu.
文摘Neurosurgery for psychiatric disorders, notably for obsessive-compulsive disorder (OCD), was initiated in Venezuela in the decade of 1970, and consisted since that time in the classic stereotactic anterior cingulotomy. In order to know further about the physiopathology of this disorder, we performed intracerebral microdialysis in 2 patients who were operated on. The aim was to measure changes in extracellular neurotransmitters within the basal ganglia. The microdialysis probes were stereotactically placed in the right caudate nucleus and in the dorsomedial nucleus of the right thalamus. The microdialysis was done before the left cingulotomy, during the pause and after the right cingulotomy. Glutamate and gamma-aminobutyric acid (GABA) changes were similar in the caudate nucleus of both patients, whereas in the dorsomedial nucleus the changes were opposite among the 2 patients. Although this study does not bring enough data to explain such differences yet, the existence of dynamic changes in the neurochemistry of the basal ganglia during cingulotomy shows that intracerebral microdialysis can help in the understanding of the pathophysiology of OCD and eventually in the design of new surgeries with better results.
文摘Clinical microdialysis allows a discrete volume of the brain to be sampled for neurochemical analysis of neurotransmitters, metabolites, biomarkers, and drugs. The technique can be safely used in humans intraoperatively, in the intensive care unit, and in ambulatory settings. Microdialysis probes, micropumps, and analytical equipment are commercially available and have been used extensively for neurochemical monitoring in traumatic brain injury, stroke, and subarachnoid hemorrhage. There has been very limited use of microdialysis in neuro-oncology, but this technique has great promise in the study of the basic neurochemistry of brain tumors, alterations in neurochemistry in response to therapy, and the pharmacokinetics of chemotherapeutic agents. Microdialysis probes may also be used to deliver drugs while simultaneously permitting monitoring of neurochemical changes induced by this therapy.
文摘A new chemically modified electrode(CME) immobilized on the surface of multi-wall carbon nanotubes functionalized with carboxylic groups was fabricated. The results indicate that the CME exhibits efficiently electrocatalytic oxidation of 6-mercaptopurine(6-MP). The CME can be used as the working electrode in the liquid chromatography for the determination of 6-MP. The peak current of 6-MP is linearly changed with its concentration ranging from 4.0×10 -7 to 1.0×10 -4 mol/L with the calculated detection limit (S/N=3) of 2.0×10 -7 mol/L. Coupled with microdialysis sampling, the method has been successfully applied to assessing the content of 6-MP in rat blood.
基金the National Natural Science Foundation of China(No.90709021)Knowledge Innovation Program of Chi-nese Academy of Sciences(No.KJCX2.YW.HO9)
文摘Some natural products,such as traditional Chinese medicines(TCMs),contain compounds with anticancer activity and have attracted a great interest in recent years as alternative anticancer therapies. A quick and convenient assay for screening antimicrotubule compounds in which in vitro microdialysis/high-performance liquid chromatography (HPLC) is used to monitor the binding of the compounds extracted from TCM Taxus cuspidata Siebold & Zucc(Taxus) to microtubules is reported. It was observed that the extract of Taxus contains at least five compounds which have affinity interaction with microtubules by biological fingerprinting analysis,and they were identified as the taxoids of taxol,baccatin Ⅲ,10-deacetylbaccatin Ⅲ(10-DAB),cephalomannine and 7-epi-10-deacetyltaxol (7-epi-10-DAT) based on the comparison of their high-performance liquid chromatographic/mass spectrometric and UV spectra with those of the standard samples,both assembly-promoting and disassembly-inhibiting characteristics of those compounds were evaluated. It was observed that baccatin Ⅲ and 10-DAB bound to microtubules and the binding degrees were influenced by GTP. Competitive binding behavior of taxol with other four taxoids to microtubules was also investigated.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 30560171).
文摘Objective To determine dopamine and its metabolites during in vivo cerebral microdialysis by routine high performance liquid chromatography with electrochemical detection.Methods Microdialysis probes were placed into the right striatum of Wistar rat brains and perfused with Ringer's solution at a rate of 1.5 μL/min.A reverse phase HPLC with electrochemistry was used to assay DA,DOPAC,and HVA after cerebral microdialysates were collected every 20 minutes from awake and freely moving rats.In order to identify the reliability of this method,its selectivity,linear range,precision and accuracy were tested and the contents of DA,DOPAC,and HVA in rat microdialysates were determined.Results The standard curve was in good linear at the concentration ranging from 74 nmol/L to 1.5 μmol/L for DOPAC(r2= 0.9996),from 66 nmol/L to 1.3 μmol/L for DA(r2=1.0000)and from 69 nmol/L to 1.4 μmol/L for HVA(r2=0.9992).The recovery of DOPAC(0.30,0.77,1.49 μmol/L),DA(0.26,0.69,1.32 μmol/L),and HVA(0.27,0.71,1.37 μmol/L)was 82.00±1.70%,104.00±4.00%,98.70±3.10%;92.30±1.50%,105.30±2.30%,108.00±2.00%;80.00±7.80%,107.69±8.00%,and 108.66±3.10%,respectively at each concentration.Their intra-day RSD was 3.3%,3.4%,and 2.5%,and inter-day RSD was 4.2%,2.3%,and 5.6%,respectively.The mean extracellular concentrations of DOPAC,DA,and HVA in rat brain microdialysates were 10.7,2.4,and 9.2 μmol/L(n=6),respectively.Conclusion The findings of our study suggested that the simple,accurate and stable method can be applied to basic researches of diseases related to monoamines neurotransmitters by cerebral microdialysis in rats.
文摘The aim of this study was to investigate the effect of 30 min forebrain ischemia,followed by120 min reperfusion on extracellular fluid(ECF)levels of dopamine(DA),norepinephrine(NE),serotonin(5-HT)and their metabolites,homovanillic acid(HVA)and 5-hydroxyindoleacetic acid(5-HIAA)in the striatum of gerbils,so as to obtain furtherinformation on the mechanism of Radix Salviae Miltiorrhizae(RSM)-inducedneuroprotection.Microdialysis was used to sample the extracellular space.Dialysate wasmeasured by high performance liquid chromatography with electrochemical detector(HPLC-ED).ECF DA,NE levels increased from basal levels by 282,227 and 221 folds,by9.14,8.51 and 8.25 folds,respectively for the three ischemic duration(0-10;11-20;21-30min).ECF DA,NE,5-HT levels in the RSM-treated group were significantly decreased ascompared with those in the control group during ischemia(P【0.01).The results suggestedthat monoamine neurotransmitters were involved in ischemic neuron damage directly orindirectly;and that RSM plays a protective role during cerebral ischemia by attenuating thedysfunctions of monoamine neurotransmitters.
文摘To investigate the effect on central nervous transmission of toosendanin (TSN), a presynaptic blocker, rat striatum was perfused in vivo with a TSN-containing artificial cere-brospinal fluid (ACSF) and the level of dopamine (DA) as well as related metabolites in the collected dialysates has been determined by a microbore HPLC with electrochemical detection (mi-crobore HPLC-ECD). The results are as follows: ( i ) TSN induced a biphasic change of DA from its basal level;( ii ) the basal contents of two metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) increased in turn and stayed at a higher level than basal control for a long period. The basal level of 5-hydroxyindoleacetic acid (5-HIAA), a metabolite of 5-hydroxytryptamine(5-HT), had a change similar to that of HVA; (iii) after per-fusion with TSN-containing ACSF, high K+-evoked DA release was inhibited. These results show that TSN does not selectively affect acetylcholine (ACh) release, but probably acts on a common
文摘A method has been established to study the competing binding of metal ions with protein by a combined technique of microdialysis with high performance liquid chromatography (HPLC). Ni2+, Cd2+, Zn2+, Cu2+ and human serum albumin (HSA) were chosen as model metal ions and protein. The experimental results show that Ni2+ and Cu2+ share a common primary binding site on HSA, and Zn2+ and Cd2+ share a different common primary binding site from them, but there is a common multi-metal binding site for all of those four metal ions. This method show advantages of fast sampling, easily to be operated and especially to be useful when ideal spectroscopic probes are not available for the study of interaction between protein and metal ions.
基金Project supported by the Chinese Academy of Sciencesthe National Natural Science Foundation of China
文摘A new method to determine the interaction between drug and protein has been developed by utilizing the technique of microdialysis sampling with the ketoprofen and the human serum albumin (HSA) as the model of drug and protein.Two kinds of binding sites of HSA to ketoprofen have been observed.The binding constants and number of binding sites obtained by the Scatchard equation are 0.799,3.18×106 mol-1 L and 2.15,2.01×105 mol-1 L,respectively The displacement binding of drugs to HSA has also been studied.The strong displacement of competitive binding of ibuprofen with ketoprofen to HSA was observed,which means that the primary binding site of HSA to ketoprofen and that to ibuprofen are the same.However,only a weaker displacement of warfarin for the association of ketoprofen with HSA was observed,which may suggest that the primary binding site of HSA to ketoprofen is different from that to warfarin.Such a displacement effect for competitive binding of drugs to HSA was explained by the displacement model
基金supported by the Malaysian Ministry of Educationthe Natural Sciences and Engineering Research Council of Canada (NSERC)
文摘This paper describes the development of a monitoring system capable of detecting the concentration of magnesium ions(Mg^(2+)) released during the degradation of magnesium implants. The system consists of a microdialysis probe that samples fluid adjacent to the implant and a catalytic biosensor specific to Mg^(2+)ions. The biosensor was fabricated on a cotton fabric platform, in which a mixture of glycerol kinase and glycerol-3-phosphate oxidase enzymes was immobilized on the fabric device via a simple matrix entrapment technique of the cotton fibers. Pure magnesium was used as the implant material. Subsequently, the concentration of ions released from the degradation of the magnesium specimen in Ringer's solution was evaluated using cyclic voltammetry technique. The device demonstrated a pseudo-linear response from 0.005 to 0.1 mmol L^(-1) with a slope of 67.48 μA mmol^(-1) L. Detectable interfering species were lesser than 1%indicating a high selectivity of the fabric device. Furthermore,the device requires only 3 μL of fluid sample to complete the measurement compared to spectroscopic method(±50 μL),hence providing a higher temporal resolution and reduced sampling time. The system could potentially provide a real time assessment of the degradation behavior, a new studied aspect in biodegradable metals research.
基金supported by the National Natural Science Foundation of China(No.81873227)。
文摘Objective To conduct a comparative study on the brain pharmacokinetics of seven ingredients(i.e.senkyunolide A,ferulic acid,formononetin,calycosin,ononin,calycosin-O-β-D-glucopyranoside,and paeoniflorin),which were the compounds of Buyang Huanwu Decoction(BHD),in normal and cerebral ischemia rats administrated intragastrically with BHD.Methods The samples of normal and permanent middle cerebral artery occlusion(pMCAO)rats were collected by using brain microdialysis technique.The concentrations of seven ingredients were determined by the HPLC-MS/MS method.After the BHD were administrated intragastrically to the rats for seven consecutive days,brain microdialysis probes were inserted into the hippocampus of rats,and then the brain microdialysates were collected at 20 min time intervals for 5 h.The separation of the seven ingredients and internal standard(IS)was carried out on an ACQUITY UPLC BEH C18(2.1 mm×100 mm,1.7μm)chromatographic column,using a mobile phase consisting of acetonitrile(containing 0.1%formic acid)and water(containing 0.1%formic acid)for gradient elution within 13 min.The ionization was conducted using an ESI source in positive ion mode.Multiple reaction monitoring mode was used for quantification of ingredients in BHD.Results Linearity,accuracy,precision,matrix effect and stability of LC-MS/MS method were all satisfactory,successfully applied to compare the pharmacokinetics of the analytes between normal and model rats after intragastric administration of BHD.Compared with the normal group,the model group after the administration of the BHD showed that T1/2 of formononetin and ononin were longer,and except for calycosin-O-β-D-glucopyranoside(P<0.01),there was no significant difference between the normal group and the model group.The C_(max) of senkyunolide A and calycosin of model group were increased,while the T_(max) of senkyunolide A was decreased,and except for the T_(max) of PF,the differences between the two groups were statistically significant(P<0.01).Conclusion The LC-MS/MS method combined with microdialysis was successfully applied to the comparative study of brain pharmacokinetics of seven ingredients in BHD.After intragastric administration of BHD,there were differences in the pharmacokinetics of seven ingredients in the brain hippocampus between normal rats and model rats,probably related to the characteristics of the ingredients and the effects of cerebral ischemia on the absorption and distribution of the ingredients.
