BACKGROUND:The electrical impedance tomography (EIT) is a kind of examination that is used to non-invasively measure the change and distribution of electrical bio-impedance by reconstructing the frequency response obtained by electrical stimuli applied onto the human body. The characteristics of impedance of any tissues are of great importance to the imaging of EIT and locating and monitoring the lesion focus.OBJECTIVE: To measure the human brain impedance in the frequency range from 0.1 Hz to 1 MHz and to compare these with those of other human tissues and the rabbit brain tissues.DESIGN: An observational experiment.SETTING:The Department of Medical Electric Engineering of the Biomedical Engineering College of the Fourth Military Medical University of Chinese PLA.MATERIALS:The experiment was conducted at the Otolaryngology Laboratory, Department of Medical Electric Engineering of Biomedical Engineering College, Fourth Military Medical University of Chinese PLA from April, 2000 to June, 2000. Two brains were harvested from two cadavers of adult men who died in less than 12 hours before the brains were taken.INTERVENTIONS :The brains were divided into 15 samples and the Solartron 1255B frequency resoonse analyzer was used to measure the complex impedance of human brain in vitro with four-electrode measurement method in the frequency range from 0.1 Hz to 1 MHz.There were also impedance interface (1294)and self-made experimental measurement box.MAIN OUTCOME MEASURES:The resistivity frequency response,curves of real part and imaginary part of complex impedance as well as the equivalent circuit model of the complex impedance.RESULTS:The resistivity of human brain tissues was about 1 200 Ω·cm in the frequency range of 0.1-100 Hz.But it decreased to 650 Ω·cm in the frequency range of 100-1×106 Hz. The real part of complex impedance remained steady in the frequency range of 0.1-100 Hz and it decreased along with the increase of frequency in the range of 100-1×106 Hz. The absolute value of frequency response curves of the imaginary part of human brain's complex impedance presented a tendency of monotonic increase.CONCLUSION: The resistivity and the real part of complex impedance curve of human brain were in accordance with those of other tissues such as muscles, the liver, kidney and lungs. The frequency response curve of the imaginary part of human brain's complex impedance was different from that of other animal tissues (such as muscles, the liver and kidney) but was in accordance with that of rabbit brain tissues in vitro. The construction of the equivalent circuit model obtained was more complex than other models known.

BACKGROUND: Electrical impedance tomography (EIT) uses non-invasive signals to probe the human body and then detect the responses on the boundary of the body in order to reconstruct an impedance distribution inside the body. Compared to CT and MRI, EIT takes the advantages of realtime technique, lower cost and easiness for both continuous monitoring and functional imaging.OBJECTIVE: This study was designed to perform the in vivo measurement of the rabbit brain impedance frequency response before and after ischemia. And it was to verify the feasibility of EIT in brain functional imaging by ischemia brain functional imaging using EIT.DESIGN: It was a single-sample experiment.SETTING: It was conducted at the Department of Medical Electronic Engineering, Faculty of Biomedical Engineering, Fourth Military Medical University of Chinese PLA.MATERIALS: This study was conducted at the Department of Medical Electronic Engineering, Faculty of Biomedical Engineering, Fourth Military Medical University of Chinese PLA from August to September 2001 and 10 healthy rabbits were selected.METHODS: Cerebral ischemia animal model was made using carotid artery ligation. Then the in vivo measurement of the rabbit brain impedance frequency response before and after ischemia was performed.Dynamic unilateral brain blood supply was recorded using EIT imaging.curves were plot before and after ischemia in the frequency range from 0.1 Hz EIT imagingRESULTS: Nine rabbits entered the statistical analysis and one was omitimpedance increased significantly. The ratio of increasing impedance can be up to 75% at frequencies lower than 10 Hz. And in the range from 1 kHz namic imaging showed that the changes in unilateral brain blood supply is accordant with the corresponding regions having a changing impedance.CONCLUSION: The changes in brain tissue impedance before and after ischemia can be imaged and it could be used as a variable for EIT imaging.

Objective To study the stability of anticoagulant peptide Hirulog-S and its lyophilized product, and to provide data on the storage conditions and clinical applications.Methods RP-HPLC was used to determine the content and the related substances of Hirulog-S and its lyophilized powder with influence factor test, accelerated test and long-term storage test.Results Light, temperature and humidity had no significant effect on the stability of Hirulog-S and its lyophilized powder in the influence factor test.The content and related substances of Hirulog-S and its lyophilized powder did not significantly change in the accelerated test ( 40℃, RH75%) and 24-month long-term storage test at room temperature and 4℃.Conclusion Hirulog-S and its lyophilized product are very stable, even after being stored at room temperature for two years.

Objective To design and synthesize a series of new type four hydrogen quinoline-benzyl/benzimidazole amine derivatives as a potential new inhibitor targeting auxiliary receptor CXCR 4, and determine their inhibitory activities to HIV-1.Methods Based on HIV-1 receptor CXCR4 inhibitors containing three nitrogen structure-activity motif and CCR5 partial hydrophobic pharmacophore , a series of new compounds were designed , synthesized and characterized by 1 HNMR and MS.The inhibitory activities of these compounds were determined using HIV-1 IIIB virus.Results and Conclusion Ten target compounds are synthesized .Four hydrogen quinoline-benzimidazole amine derivatives exhibit good anti-HIV activity(IC50 <1 μmol/L), but four hydrogen quinoline-benzyl amine compounds are less active ((IC50 >8 μmol/L).

Objective To investigate the diagnosis and treatment of pancreatic carcinoma with acute and chronic pancreatitis as the initial symptoms.Methods The clinical data of 13 patients with pancreatic carcinoma who were admitted to the First Affiliated Hospital of Dalian Medical University and the Affiliated Central Hospital of Dalian Medical University from January 2003 to June 2014 were retrospectively analyzed.The first symptoms were acute and chronic pancreatitis.Laboratory and imaging examinations were carried out on all the patients,and the treatment plan was designed according to the location and stage of the tumor as well as the patient's wishes.Surgery,radiotherapy,chemotherapy and other symptomatic treatment were selected.All the patients were followed up by telephone interview till July 2014.Results The major symptoms included abdominal pain and lumbodorsal pain (7 patients).Of the 13 patients,1 patient refused to received laboratory examination,and the levels of CA19-9 of the other 12 patients were elevated (the levels of CA19-9 of 11 patients were above 1 × 105 U/L).The levels of carcinoembryonic antigen (CEA) of 5 patients were elevated.Thirteen patients received plain or enhanced abdominal computed tomography (CT),3 received magnetic resonance imaging (MRI) and 3 received sonography.The tumors located at the head of the pancreas wcrc observed in 9 patients,tumors located at the neck of the pancreas was observed in 2 patients,and tumors located at the tail of the pancreas were observed in 2 patients.The sizes of the tumors ranged between 1.7 cm × 1.7 cm and 4.9 cm × 4.8 cm.The common bile duct,intrahepatic bile duct and pancreatic duct of 7 patients were dilated.The superior mesenteric vein of 3 patients were invaded by the tumor.The lymph nodes of 4 patients were swollen,and 3 patients had peritoneal effusion.The results of CT confirmed that 2 patients were with cholecystolithiasis,and the results of magnetic retrograde cholangiopancreatography (MRCP) confirmed that 1 patient had choledocholithiasis.The size of he pancreas of all the patients were increased using ultrasonography,and the main pancreatic ducts of 2 patients were dilated.Ten patients were diagnosed as with advanced pancreatic carcinoma.All the patients were staged by the imaging findings,5 patients belonged to stage Ⅱ and 8 belonged to stage Ⅳ.Two patients underwent pancreaticoduodenectomy,and 1 of them underwent postoperative radiotherapy and chemotherapy,and the other patient underwent palliative biliary enteric anastomosis and gastrojejunostomy.Two patients were treated by chemotherapy and 1 by radiotherapy in the 10 patients who did not received surgery.The rest 7 patients were treated with symptomatic therapy.The pathological results of the 2 patients who underwent pancreaticoduodenectomy were both moderately and poor-differentiated adenocarcinoma,and the size of the tumors were 4.0 cm × 3.0 cm × 2.5 cm and 2.5 cm × 2.0 cm × 1.0 cm.Three patients lost to follow-up among the 13 patients.The survival time of the patients with acute pancreatitis as the initial symptom ranged from 2.0 months to 6.0 months,and the median survival time was 4.5 months.The survival time of the patients with chronic pancreatitis as the initial symptom ranged from 0.5 months to 10.0 months,and the median survival time was 3.0 months.The median survival time of the 4 patients with elevated level of CEA was 3.5 months,and the median time of the 5 patients with normal level of CEA was 5.4 months.All the 10 patients who were followed up died of tumor recurrence and metastasis.Conclusion The clinical presentation of patients with acute and chronic pancreatitis as the initial symptoms is atypical,and it is difficult to achieve early diagnosis.Dynamic monitoring and combined diagnosis with laboratory and imaging examinations will improve the accuracy of diagnosis.Surgery based treatment is the preferred option.

Objective To assess the effect of low-dose cytarabine and aclarubicin in combination with gran-ulocyte colony-stimulating factor (G-CSF) protocol (CAG) in patients with acute myeloid leukemia (AML),and to understand the potential factors affecting the outcome of CAG induction therapy, therefore to find the optimum pa-tients for CAG therapy. Methods Twenty-one AML patients were enrolled in the current study. All patients were treated with CAG regimen including cytarabine (10 mg/m~2, subcutaneously, every 12 h, days 1 - 14), lacinomycin (5～7 mg/m~2,intravenously,every day, days 1 -8) ,and G-CSF (200 μg/m~2,subcutaneously, every day,12 h be-fore Ara-C was given) priming. Results The overall complete remission (CR) rate of the 21 AML patients was 66.7% (14/21). The CR rates was 87.5% (7/8) in patients older than 60 yrs,60.0% (9/15) in the refractory or relapsed patients,83.3% (5/6) in the MDS transformed AML patients. The CR rates for patients with hyperprolif-erative BM and median to poor proliferative BM were 33.3% and 91.7% ,respectively(P =0.009). The median o-verall survival (OS) time of the 21 AML patients was 450 days. Two-year survival rate estimated by Kaplan-Meier Method was 30.6%. The overall median disease free survival (DFS) was 165 days. The median OS time for those refractory or relapsed was 435 days. The median OS time for those with poor cytogenetic state or standard or good cytogenetic state was 140 days and 620 days, respectively (P = 0.001). The median OS time for patients with hyperproliferative BM and median to poor proliferative BM was 321 days and 620 days, respectively (P = 0.05). The median recovery time of granulocytes above 1.0×10~9/L was 8 days. The median duration of fever was 3.5 days. The rate of infections exceeding WHO grade Ⅱ was 42.9%. No early death occurred. Conclusions The CAG induction therapy may have a higher CR rate in patients with refractory or relapsed AML, elderly AML and secondary AML from MDS transformation, and extend the median overall survival time in refractory or relapsed patients. CAG therapy can not improve the outcome of patients whose BM was in high grade proliferation state or whose cytogenetic state was poor. CAG therapy can shorten the duration of agranulocytosis and decrease the inci-dence of serious infection. Therefore, CAG therapy is worth recommending to patients who can not endure the rou-tine intensive chemotherapy.

The complex impedance measurements of human brain tissue in vitro are made by using four-electrode measurement methods in the frequency range from 0.1 Hz to 1 MHz. The Solartron 1255 B frequency response analyzer is used. The frequency response curves of the imaginary part of human brain's complex impedance do not appear as a single peak curve which other bio-tissues show, and the Cole-Cole diagram of human brain is different from the others as well. The construction of the equivalent circuit model obtained is more complex. However, these characteristics of human brain are all the same as rabbit brain's. The equivalent circuit model obtained will be helpful to constructing the equivalent circuit model of human head in the EIT researches.
Adult ; Brain ; physiology ; Electric Impedance ; Electrodes ; Humans ; In Vitro Techniques ; Male ; Models, Biological

The human skull impedance was quantitatively measured by means of Frequency Response Analyzer and its software. The impedance-frequency response curves of human skull were obtained. By analyzing the curves, we found that the characteristic frequency of human skull should be around 10 KHz.
Adult ; Electric Impedance ; Humans ; Middle Aged ; Skull ; physiology ; Time Factors

It is the intent of this paper to develop better reconstruction algorithm for electrical impedance tomography (EIT). Simulation study of the reconstruction algorithm based on the sensitivity theorem is made and the reconstruction algorithm is compared with other normal algorithms. The results indicate that sensitivity method as a kind of static reconstruction algorithm has higher accuracy and speed of iteration, so it is worth researching for laboratory modality work.
Algorithms ; Computer Simulation ; Electric Impedance ; Tomography ; methods

Induced-current electrical impedance tomography (ICEIT) is a newly hot research field in electrical impedance tomography (EIT) because of its advantages of contactless exciting. A preliminary ICEIT system with 3 excitation coils has been accomplished. It includes the constant current source (CCS), power amplifiers, excitation coils,physical phantom, measurement-mode setting circuit, signal measuring block, DAC and digital I/O card. The CCS is accomplished with Direct Digital Synthesis (DDS) technique. Its frequency is 46.875 KHz. Its output current is divided into 16 steps from 0.16 mA to 2.56 mA which can be set by computer. The three driving coils have the same diameter of 50 cm, each coil's inductance is 193.5 microH. The power amplifier can provide 800 mA driving current (f = 46.875 KHz) to the coil under +/- 25 V power supplying. The signal from measurement electrodes is switched to measurement channel which includes IA, BP filter and synchronized demodulator, then the analog signal is converted to digital signal by a 12b A/D Card and the data is acquired by DMA mode. Our experiments show that a distinguish change of signal from the surface electrodes can be acquired by the experimental system when different objects are placed in the physical phantom. And 3 x 31 signals for preliminary imaging have been acquired.
Algorithms ; Amplifiers, Electronic ; Electric Impedance ; Electrodes ; Electromagnetic Fields ; Electromagnetic Phenomena ; instrumentation ; Humans ; Image Processing, Computer-Assisted ; Phantoms, Imaging ; Tomography ; instrumentation ; methods