Dihydromyricetin down-regulating the expression of nod-like receptor protein-3 in the brain tissue of ischemic stroke in rats / 解剖学报

[Abstract] Objective To investigate the role of dihydromyricetin (DHM) in the treatment of ischemic stroke in rats, and to explore the effect of DHM on the expression of inflammasome. Methods The middle cerebral artery occlusion (MCAO) model was induced by endovascular suture method. The therapeutic effect and mechanism of DHM were investigated by Longa score, TTC staining, Nissl staining, immunohistochemical staining and Western bloting. Results After DHM treatment, the motor capacity of MCAO rats was significantly improved, the infarct volume was significantly reduced, the brain structure and neuron morphology were improved, and the expressions of nod-like receptor protein-3 (NLRP3) and interleukin-1(IL-1) decreased significantly. Conclusion DHM can down-regulate the expression of NLRP3 and thus reduces the cerebral infarction volume and improves neurobehavioral performance in MCAO rats.

Establishment of mouse myocardial infarction model and early electrocardio- gram assessment / 药学实践杂志

Objective To establish and optimize a mouse myocardial infarction (MI) model, and to use twice limb lead ECGs immediately after coronary ligation and 4 h after surgery to evaluate the occurrence of myocardial infarction. Methods Twenty-nine male C57BL/6J mice were anesthetized with isoflurane. then a myocardial infarction model was established by ligating the left anterior descending (LAD) coronary artery through the third/fourth intercostal space of left anterior chest. Immediate and 4 h postoperative limb lead ECGs were performed. Twenty-four hours after surgery, the chest was opened and the occurrence of myocardial infarction was evaluated. The heart samples were taken for TTC staining to determine the infarct area and calculate the infarct area. Results During the mice underwent coronary artery ligation the intraoperative mortality was 6.8% (2/29), and the early postoperative (<4 h) mortality was 10.3% (3/29). The 24 h survival rate was 82.8% (24/29). 24 hours after TTC staining confirmed the occurrence of infarction, the myocardial infarction model was established. The success rate of the model was 79.3% (23/29), and the average infarct size (infarcted myocardial weight / whole ventricular weight) was (28 ± 6)%; The mice successfully established by the model showed obvious ST-T changes in the ECG at 4 hours after surgery, suggesting that a myocardial infarction has occurred. Conclusions The mouse myocardial infarction model was successfully established. The combined use of ECG immediately after surgery and 4 h after surgery could be used as a rapid and non-invasive evaluation method for mouse myocardial infarction.

Study of No Observed Adverse Effect Level of Nickel and Its Preliminary Evaluation Biocompatibility / 中国医疗器械杂志

The purpose of this study was to investigate the NOAEL of the nickel ion and provide with basic data for the biological evaluation of those medical devices containing nickel. Five groups SD rats were repeatedly exposed during 14 d respectively to nickel at first stage doses of 4.9, 3.7, 2.5 mg/(kg.d), and the second stage doses of 1.2, 0.25 mg/(kg.d) by the intravenous route. The results showed that the NOAEL of nickel ion is 0.25 mg/(kg.d) for SD rats, and the result was verified by subchronic systemic toxicity test of nickel alloy. The threshold of toxicological concern (TTC) of nickel is 150 μg/d (based on application of 100-fold uncertainty factor and a body weight of 60 kg)deduced by these data.

Application of the Threshold of Toxicological Concern (TTC) to Biological Evaluation of Medical Devices / 中国医疗器械杂志

The threshold of toxicological concern (TTC), a risk estimation method based on compound structurally-related toxicity data, has been widely used by many countries and regions for the safety risk assessment of food packaging materials and additives etc. Toxicological risk estimation is of importance in the biological evaluation of medical devices. Application of the TTC approach to leachable from medical devices may reduce or replace some unnecessary biocompatibility tests, but consideration should be taken for contact duration and route differences, which could affect the applicability of TTC. We herein focused on analyzing the eligibility of TTC for its further application in biological evaluation of medical devices.

Detection of hypothalamic infarction in intraluminal middle cerebral artery occlusion model rat by DWI scanning / 上海交通大学学报（医学版）

Objective: To detect and evaluate the hypothalamic infarction in middle cerebral artery occlusion (MCAO) model rat. Methods: For 15 Sprague-Dawley rats weighed 200-250 g, aged 6-8 months, their right middle cerebral artery was occluded for 90 min by a silicon-coated 4-0 nylon filament and reperfused. Sprague-Dawley rats underwent diffusion weighted MR imaging (DWI) scanning (at 1 h and 24 h after reperfusion) and 2, 3, 5-triphenyl tetrazolium chloride (TTC) staining (at 24 h after reperfusion) to determine the hypothalamic and cerebral infarct volume. The relationship between hypothalamic infarct volume and cerebral infarction volume was analyzed by DWI scanning. The results of TTC staining were compared with those of 24 h DWI scanning. Results: Fifteen Sprague-Dawley rats successfully received intraluminal MCAO/reperfusion procedures. The incidences of hypothalamic infarction on brain DWI scanning and TTC staining were 100% and 40% at 24 h after reperfusion, respectively. Therefore, DWI scanning was more sensitive than TTC staining to detect hypothalamic injury (P=0.001). The hypothalamic infarct volume on DWI scanning was (8.59±2.89) mm3 and (11.65±3.19) mm3 at 1 h and 24 h after reperfusion, respectively. On DWI scanning, hypothalamic and cerebral infarct volume at 24 h after reperfusion were correlated with each other significantly (r=0.573, P=0.025), so were the increases of hypothalamic and cerebral infarct volume (r=0.554, P=0.032) from 1 h to 24 h. Conclusion: DWI scanning was more sensitive than TTC staining to detect hypothalamic injury in intraluminal transient MCAO model. Hypothalamic and cerebral infarct volume were correlated with each other.

Protection of Batroxobin Injection on super acute stage of thromboembolic cerebral stroke in rats / 药物评价研究

Objective To observe the effects of Batroxobin Injection on thromboembolic cerebral stroke by magnetic resonance imaging (MRI) and TTC staining.Methods Rat model ofthromboembolic stroke was prepared after the left middle cerebral artery was occluded by autologous blood clots,and 32 rats with successful operation were divided into four groups according to the degree of neurological deficit:model group,Batroxobin Injection low and high dose (0.3,1.0 BU/kg) group,and rt-PA (9 mg/kg) group,with eight rats in each group,and other eight rats in Sham group.Rats were administered 1 h after modeling by tail iv method.At 6 h after administration,neurological deficit score and MRIincluding SE-T2WI and DWI sequence scanning were measured.At 24 h after administration,the brain was cut for TTC staining to measure the infarct area,and blood FIB was measured.Results Compared with model group,Batroxobin Injection 0.3 BU/kg treatment for 24 h (P ＜ 0.05),1 BU/kg treatment for 6 and 24 h (P ＜ 0.05,0.01) could significntly improve the neurological function scores of rats.MRIresults showed that Batroxobin Injection at dose of 0.3 and 1 BU/kg significantly reduced the lesion range (P ＜ 0.05 and 0.01).Results of TTC stain showed that Batroxobin Injection at dose of 0.3 and 1 BU/kg significantly reduced the infarct size (P ＜ 0.05).Batroxobin Injection at doses of 0.3 and 1 BU/kg can significantly lower plasma FIB concentration (P ＜ 0.05,0.01,0.001) 6 and 24 h after administration.Conclusion Batroxobin Injection can improve the damaged neural function,reduce scope of lesions,decrease plasma fibrinogen,with protective effects for cerebral ischemia in rats.

Protection of Batroxobin Injection on super acute stage of thromboembolic cerebral stroke in rats / 药物评价研究

Objective To observe the effects of Batroxobin Injection on thromboembolic cerebral stroke by magnetic resonance imaging (MRI) and TTC staining.Methods Rat model ofthromboembolic stroke was prepared after the left middle cerebral artery was occluded by autologous blood clots,and 32 rats with successful operation were divided into four groups according to the degree of neurological deficit:model group,Batroxobin Injection low and high dose (0.3,1.0 BU/kg) group,and rt-PA (9 mg/kg) group,with eight rats in each group,and other eight rats in Sham group.Rats were administered 1 h after modeling by tail iv method.At 6 h after administration,neurological deficit score and MRIincluding SE-T2WI and DWI sequence scanning were measured.At 24 h after administration,the brain was cut for TTC staining to measure the infarct area,and blood FIB was measured.Results Compared with model group,Batroxobin Injection 0.3 BU/kg treatment for 24 h (P ＜ 0.05),1 BU/kg treatment for 6 and 24 h (P ＜ 0.05,0.01) could significntly improve the neurological function scores of rats.MRIresults showed that Batroxobin Injection at dose of 0.3 and 1 BU/kg significantly reduced the lesion range (P ＜ 0.05 and 0.01).Results of TTC stain showed that Batroxobin Injection at dose of 0.3 and 1 BU/kg significantly reduced the infarct size (P ＜ 0.05).Batroxobin Injection at doses of 0.3 and 1 BU/kg can significantly lower plasma FIB concentration (P ＜ 0.05,0.01,0.001) 6 and 24 h after administration.Conclusion Batroxobin Injection can improve the damaged neural function,reduce scope of lesions,decrease plasma fibrinogen,with protective effects for cerebral ischemia in rats.

Hyperglycemia aggravated cerebral ischemia/reperfusion injury by inhibiting mitophagy / 中国药理学通报

Aim Toinvestigatetheroleofhyperglyce-mia in cerebral ischemia/reperfusion(I/R)injury with a middle cerebral artery occlusion(MCAO)rat model anditsmechanism.Methods EightyhealthymaleSD rats were randomly assigned into sham group, I/R group (normoglycemia),hyperglycemic I/R groupⅠ(HG1 )and hyperglycemic I/R groupⅡ(HG2 ).The cerebral I/R model was established by occluding the middle cerebral artery(MCA)in rats.Hyperglycemia was induced by intraperitoneal injection of 50% glu-cose solution.Neurological deficit was determined by Ludmila Belayev test;infarct size and brain edema were measured by TTC staining;mitophagy was ob-served by double immunofluorescent staining and elec-tron microscope.The expressions of autophagy-related proteins(LC3 and Beclin-1 )and apoptosis-related pro-teins(Cyt-C,AIF,caspase-9 and caspase-3 )were ex-aminedbyWesternblotfurtherly.Results Bloodglu-cose level was controlled at 4 mmol·L-1 (normoglyce-mia),10 mmol · L-1 (HG1 ) and 20 mmol · L-1 (HG2)respectively.There were no significant differ-ences between model group and HG1 group in neuro-logical deficit scores,infarct volume and edema size(P>0. 05 ).However,these indications in HG2 group were significantly increased compared with model group (P<0. 05 ).After 3 days of reperfusion,the level of mitophagy was significantly reduced accompanied with increased mitochondria damages in HG 2 group (P <0. 05 ),and the expressions of mitochondrial related ap-optotic proteins(Cyt-C,AIF,caspase-9 and caspase-3 ) were significantly increased accordingly compared to modelgroup.Conclusions Mildhyperglycemiacan not intensify the cerebal ischemic injury.In contrast, severe hyperglycemia significantly aggravates the brain ischemic injury by inhibiting the removal of injured mi-tochondria in a manner of mitophagy,thus amplifying the mitochondrial mediated cascade damage responses.

Preparation of a rat model of neonatal hypoxic-ischemic encephalopathy / 中国比较医学杂志

Objective To simulate the process of hypoxic?ischemic brain injury at high altitude in a simulated cabin with plateau low pressure environment, and to prepare a rat model of cerebral injuries at different high altitudes. Method Thirty?two 0?day?old neonatal SD rats were divided into four groups, namely group A ( control group) and three test groups:group B (2000 m group), group C (4000 m group), and group D (6000 m group). The rats of control group were reared in a barrier environment. The rats of test groups were placed in a simulated cabin with plateau low pressure environment, and to prepare neonatal cerebral ischemia?hypoxia model by sport activities. The sport movements were carried out in the cabin in a swimming groove 60 min/d, and not less than 20 hours a day at high altitude low pressure environment. Zea Longa 5 point scale standard was used to determine the behavioral scores at the 3 th 7 th 11 th 15 th days, and samples were collected on the 15th day to observe red blood cell morphology using HE and 2, 3, 5?triphenyltetrazolium chloride ( TTC ) staining and ultrastructure by scanning electron microscopy. Result ( 1 ) The neurological scores of the test groups A, B, C were significantly different from that of the control group (P<0?05), and the scores of test group D and control group were very significantly different ( P <0?01 ) . ( 2 ) The histopathological examination using HE staining showed inflammatory cell infiltration in all rats of the test groups, and the extent of inflammatory cell infiltration was positively correlated with the increase of altitude. ( 3 ) The histopathology with TTC staining revealed prominent ischemia in the cerebral cortex of rats in the plateau hypoxic environment. ( 4 ) Scanning electron microscopy showed that the rat erythrocytes were cap?like in the group B, irregular in the group C, and zigzag shape in the group D. Conclusions In this study, a rat model of neonatal hypoxic?ischemic encephalopathy ( HIE) is successfully established by hypoxic cabin combined with sport activity. This model is stable, reliable, more closely mimicking the pathogenesis and clinical manifestation of neonatal HIE than models prepared with other methods, therefore, may be used in related research.

Study on pollen viability and morphological characteristics of Zanthoxylum nitidum / 中草药

Objective: To investigate the pollen morphological and physiological characteristics of Zanthoxylum nitidum. Methods: The pollen grain viability was studied using an in vitro method and the optimal concentration of sucrose, H3BO3, and CaCl2 on pollen germination were investigated by 3414 test. At the same time it contrasted with the I2-KI and TTC methods to find the proper determination method for Z. nitidum pollen vitality. And then It was further studied that different storage time and methods had an effect on pollen grain viability by having established method. Pollen morphology was studied by scanning electron microscopy (SEM). Results: The I2-KI and TTC methods were not fit for determining the mature pollen vitality of Z. nitidum. The optimal medium was 10% sucrose + 0.1 mg/mL H3BO3 + 0.1 mg/mL CaCl2 on pollen germination in vitro and the pollen germination ratio was up to 66.67%. Pollen viability was the highest in 24 h and it could keep about 15 d in 4 ℃ environments. The pollen grains were 3-colpate prolate, with reticulate ornamentation. Conclusion: The determination and storage of pollen grain viability is established preliminarily to provide reliable basis of knowing physiological characteristics, breeding and taxonomy.

Protective effect of hydrogen sulfide on focal cerebral ischemia/reperfusion injury in rats and its mechanism / 中国药理学通报

Aim To investigate the protective effects of hydrogen sulfide ( H2 S) on focal cerebral ischemia/reperfusion injury in rats and the possible mechanisms. Methods Male Sprague Dawley rats were divided into three groups randomly: sham-operated group, cerebral ischemia/ reperfusion ( I/R) group and sodium hydro-sulfide ( NaHS ) + I/R group. The left temporary middle cerebral artery occlusion ( MCAO ) model was established by the line-embolism method. After rats were suffered 2h/24h ischemia/reperfusion stress, the mortality rate was evaluated, and the nervous function-al defect degree was evaluated by Longe scoring, the volumes of cerebral infarction was evaluated by 2 ,3 ,5-triphenyltetrazolium chloride ( TTC) staining, and the expression of P2X7 receptor protein in brain tissue was detected by the immunofluorescence method. Results The mortality rate in NaHS + I/R rats ( 29.41%) was obviously lower than those of I/R group ( 42 . 86%) . The nervous defect scores in NaHS + I/R rats were significant lower than those of I/R group ( P <0.05 ) . The volumes of cerebral infarction in NaHS +I/R group (21.88% ±3.53%) were significant lower than those of I/R group ( 36.71% ±3.73%) ( P <0.01 ) . The results of immunofluorescence showed that the positive expression cells of P2X7 receptor protein in cerebral cortex and hippocampal CA1 area of I/R group were significantly higher than those of sham-op-erated group(P<0. 01). However, compared with I/R group, the positive expression cells of P2X7 receptor protein in cerebral cortex and hippocampal CA1 area of NaHS + I/R group were significantly decreased ( P<0. 01). Conclusions H2S exerts the neuroprotective effect on focal cerebral ischemia/reperfusion injury in rats, and the protective mechanism might be associated with down-regulating the expression of P2X7 receptor protein in brain tissue.

Development and application of triphenyltetrazolium chloride (TTC) method for determining the survival of cultured cells / 军事医学

Objective To develop a precise and reliable method to determine mammalian cell survival using the triphe-nyltetrazolium chloride (TTC) solution.Methods Different amounts of TTC solution were added to the cultured cells in order to find the optimal concentration .The correlation between the cell number and the measured optic density value was analyzed.In addition, the TTC method was compared with traditional MTT assay .Results The TTC assay could precisely reveal the viability of cultured cells as well as the MTT method , but the non-specific reaction of the MTT reagent by other antioxidants could result in unreliable overestimation of the cell number .Conclusion The TTC assay can be used to deter-mine the survival of cultured cells more precisely .

Comparison of thermotolerant coliforms and Escherichia coli densities in freshwater bodies

Fecal bacterial indicator analyses have been widely used for monitoring the water quality. This study was designed to determine the ratio between the density of Escherichia coli and other Thermotolerant Coliforms (TtC) bacteria from freshwater samples collected for a two-year period of monitoring. TtC were enumerated by membrane filtration on mFC agar. E. coli enumeration was done by two methods: TtC colonies identified in mFC were inoculated in EC-MUG or water samples were filtered and inoculated in modified mTEC agar media, and both methods were compared for quantitative recovery of E. coli. The results pointed out a mean percentage of E. coli among other thermotolerant coliforms (E. coli/TtC ratio) of 84.3% in mFC media. Taking these results into account, a mandatory standard of 1000 thermotolerant coliforms would correspond to 800 E. coli and the adoption of these E. coli based standards will represent a major improvement for the monitoring of freshwater quality.

Time- dependent Changes of the Infarct Volume in a Rat Stroke Model: A Comparison of the Use of MRI and TTC- staining as Monitoring Tools / 대한뇌혈관외과학회지

OBJECTIVES: Serial changes of focal ischemic lesions as seen on magnetic resonance (MR) images and triphenyltetrazolium chloride (TTC)-stained samples of transient middle cerebral artery occlusion in a rat model were evaluated to investigate the natural course of the lesions and the feasibility of the use of each method as a monitoring tool. METHODS: Transient middle cerebral artery occlusion (MCAO) was induced in fifteen adult female Sprague Dawley rats using the method of intraluminal vascular occlusion. Two hours after MCAO was induced, reperfusion was performed. Serial MR images were obtained and the volume of the brain infarct was estimated. For macroscopic and microscopic evaluation of the ischemic lesions, the ten animals were sacrificed at different times after MCAO. The rat brains were then removed and six coronal sections were made. Each section was incubated at 37 degrees C in 2% TTC solution for 15 minutes. RESULTS: Postischemic injury evaluations that were made periodically for eight weeks revealed that the lesion volume as determined from T2 maps had reached a peak on the second day after ischemic injury and the volume decreased afterwards for one week; by the fourth week, the lesion volume again increased to stabilize initial lesion development. There were considerable discrepancies between the infarct area of the samples determined by TTC staining and the in vivo infarct area estimated from the MR images, especially for late stages. CONCLUSION: T2 map MR images, with a careful consideration of the natural course of infarction development, can provide an adequate and noninvasive means to evaluate the degree of ischemic injury under diverse experimental circumstances.

M. leprae typing by genomic diversity of clinical isolates in Korea / 나학회지

Recently, PCR-based typing would be of great value for Epidemiological investigation to identify infectious source of leprosy, understand transmission pattern, and distinguish between relapse & re-infection. Variable TTC DNA repeats in non-coding region and 6bp(GACATC) tandem repeats in rpoT gene revealed PCR products of different size may be useful to investigate the epidemiology of leprosy. Authors have typed clinical isolates of M. leprae in Korea using difference of TTC DNA repeats in non-coding region and 6bp(ACATCG) tandem repeats in rpoT gene. Of the sequence analysis of isolates(M. leprae) of 52 patients(44 Koreans, 8 foreigners; Bangladesh, Indonesia, Philippine, Sri Lanka, Thailand) M. leprae with 12 TTC repeats was showed most common(13 cases, 29.5%) in 44 Korean isolates and 42 Koreans(95.5% of Korean isolates) isolates demonstrated four copies of 6bp(ACATCG) tandem repeats in rpoT gene and the isolates with three copies were found in 2 Koreans and 8 foreigners.

Development of a Rapid System for Bacteria Identification in 24 Hours / 中华医院感染学杂志

OBJECTIVE To develop a rapid system for bacteria identification and susceptibility test in 24 hours,and provide bacteriological evidence for the control of nosocomial infection and the timely diagnosis and treatment.METHODS The simple constant temperature box was replaced by revolving constant temperature box;2,3,5-triphenyltetrazolium chloride(TTC) and succinate were added to the culture bottle and the culture medium of drug susceptibility;the concentration of the reactive substrate in the bacterial biochemical tube and the number of the inoculated bacteria were increased at the same time.RESULTS The time of positive blood culture in the revolving constant temperature box was significantly shorter than that in the simple one(?2=74.92,P

The Study of Epidemiological investigation of Leprosy by Using Polymerase Chain Reaction / 나학회지

Recently, PCR-based typing would be of great value for Epidemiological investigation; to identify infectious source of leprosy, understand transmission pattern, and distinguish between relapse & re-infection. Variable TTC DNA repeats in non-coding region and 6bp(ACATCG) tandem repeats in rpoT gene revealed PCR products of different size may be useful to investigate the epidemiology of leprosy. Authors have typed clinical isolates of M. leprae in Korea using difference of TTC DNA repeats in non-coding region and 6bp(ACATCG) tandem repeats in rpoT gene. Of the sequence analysis of isolates(M. leprae) of 20 patients(17 Koreans, 3 foreigners; Bangladesh, Thailand, Philippine), M. leprae with 11 and 12 TTC repeats was showed most common and the isolates with 10 repeats were found in only two foreigners, and 16 Koreans isolates demonstrated four copies of 6bp(ACATCG) tandem repeats in rpoT gene and the isolates with three copies were found in only one Korea and 3 foreigners.

Study on viability of Cistanche deserticola seeds / 中草药

Objective To improve the 2,3,5-triphenyl tetrazolium chloride (TTC) solution method for measuring the viability of Cistanche deserticola seeds and investigate the change in viability during storage at 5 ℃. Methods The effect of the testa,TTC concentration,sodium hypochlorite concentration (NaClO),and staining time were studied,and seed viability during storage at 5 ℃ was measured with the improved method. Results Seeds were kept for 48 h in 0.5% TTC solution at 40 ℃,and then for 2 h in 0.2% NaClO solution;Seed viability was measured under a stereomicroscope. Storing seeds of C. deserticola for 1 to 2 years at 5 ℃ had no significant effects on their viability. However,the percentage of seeds with high viability was increased with the extension of the storage time at 5 ℃. Conclusion A convenient and rapid method for measuring the viability of C. deserticola seeds is developed. Storing C. deserticola seeds at 5 ℃ could improve their viability

Measurement of Regional Tissue Water and Ionic Concentrations During the Evolution of Infraction and the Therapeutic Value of Nimodipine in Rat Middle Cerebral Artery Occlusion Model of Ischemia

The evolution of infarction in the rat middle cerebral artery(MCA) occlusion model was examined by atomic absorption spectrometric measurements of Na, K and Ca concentrations in brain tissue sample. At 2, 4, 6, 8, and 24 hours after MCA occlusion and sham occlusion the brain tissue samples were obtained. Tissue water concentrations were estimated from dry-wet weight measurement. The effects of nimodipine(2 microgram/kg/min for 10 min) administered intra-venously at 4 hours(Group A), 6 hours(Group B), and 9 hours(Group C) after MCA occlusion were investigated on both the size of infarction and tissue water, Na, K, Ca concentrations at 24 hours. The result were as follows : 1) Normal concentrations of water, Na, K, and Ca averaged 0.793+/-0.009ml, 54.06+/-4.18 micromole, 81.04+/-3.44 micromole, and 3.578+/-0.712 micromole/gm wet weight. At the infarct site by 24 hours, the changes of tissue water and ionic concentrations were conspicuously evident so that water increased by more than 10%(p<0.005), Na increased by more than 120%(p<0.005), K decreased by more than 75%(p<0.005), and Ca increased by more than 200%(p<0.005). 2) The remarkable shifts of Na, K, and Ca concentrations occurred at 4-6 hours so that 60-85% of the ionic shifts developed by 6 hours. This characteristics of chronological ionic changes correlated well with the findings of 2% TTC staining during the evolution of infarction. Water concentrations increased rapidly at 2-4 hours so that nearly 80% of water shift developed by 4 hours. 3) In group A(administered at 4 hours), nimodipine treatment significantly reduced both the ionic shifts at the infarct site and the size of infarction compared with non-treated rats(p<0.05). 4) In group B(administered at 6 hours), nimodipine treatment did not significantly reduce the ionic shifts but did reduce the size of infarction compared with non-treated rats(p<0.05). In group C(administered at 8 hours), nimodipine treatment significantly reduce neither the ionic shifts nor the size of infarction. In summary it was concluded that the progressive changes in tissue water and ionic concentrations developed at the infarct sites and the critical period of the changes was between 4 and 6 hours, and nimodipine treatment was effective when administered within 4 hours. The results suggested that measurement of tissue ionic concentrations could be used as an alternative method for assessing tissue damage and a reliable method to quantify the tissue damage. This method may be useful for determining the time window for therapeutic protocol, as well as for evaluating therapeutic effects.

Effect of Tissue Plasminogen Activator on Autologous Arterial Emboli in the Cerebral Circulation of Rabbit Model

The safety and efficacy of intravenous tissue plasminogen activator(tPA) on the condition of ruling out the significant risk were studied at 6 and 12 hours after cerebral artery embolization in rabbit model. The time selection was chosen to stimulate the analogous clinical situation. The safety and effectiveness of tPA in experimental and clinical treatment of acute coronary thrombosis have been established. Tissue plasminogen activator is an endogenous fibrin-specific serine protease with the potent thrombolytic activity that has been produced recently by recombinant DNA technology. The acute cerebral thromboembolic model was induced by injecting three 0.5X1.0mm fragments of autologous arterial thromi into internal carotid artery through the intra-arterial catheter. The autologous arterial thrombi was obtained from the traumatized arterial endothelium by scratching the lumen of auricular artery using modified spinal needle. The experimental group was divided into four groups : (1) group Ia : saline-treated(1 ml/kg) control group at 6 hours after embolization(n=10), (2) group Ib : tPA-treated(1 mg/kg) at 6 hours after embolization(n=10), (3) group IIa : saline-treated control group 12 hours after embolization(n=10), (4) group Iib : tPA-treated group 12 hours after embolization(n=13). The experimental rabbits were sacrificed at 24 hours after injection of tPA(1 mg/kg) or saline(1 ml/kg) in each group. Brain was cut into 0.5 cm thick coronal sections, which were stained with triphenyltetrazolium chloride to define the areas of infarction. The transparent plastic sheets were placed on the each section, and the total area of the brain slice and the area of infarction were measured by the plannimeter(as outlined by TTC staining). The percentage area of whole brain infarction was calculated as(the sum of infarcted area/the sum of brain slice areas)x100% for each rabbit. We also observed the pathologic findings with hematoxylin-eosin staining. The results were as follows : 1) Only 1 rabbit treated with tPA at 12 hours after occlusion exhibited the gross hemorrhage. 2) The infarcted area was limited to the basal ganglia and cortex in all group. 3) The mean percentage area of whole brain infarction averaged 18.6+/-1.94% in group Ia, 6.32+/-1.02% in group Ib, and 20.8+/-3.34% in group IIa, 6.78+/-1.40% in group IIb. One-way ANOVA test of infarction size showed the significant differences(p<0.05) between the tPA-treated group and the saline-treated control group, but no difference between the groups treated with same agent. 4) Under the study of microscope, infarcted area of saline-treated control group was more extended than that of tPA-treated group. Congulation necrosis and degeneration of neuronal cells could be seen. But the infarcted area of tPA-treated group was smaller than that of saline-treated control group. Only collection of foamy macrophages adjacent the necrotic area could be seen in tPA-treated group. These results suggest that tPA therapy may be safe and efficacious during the interval of 6 to 12 hours after embolization.