Pseudomonas sp. M18 is one of plant growth-promoting rhizobacteria capable of producing two kinds of anti-fungal agents: phenazine-1-carboxilic acid (PCA) and pyoluteorin (Plt). The pqsR gene, which encodes a LysR family member PqsR, was amplified from chromosomal genome of strain M18. Using the homologous recombination technique, a chromosomal pqsR inactivated mutant strain M18PRG was constructed in Pseudomonas sp. M18. To study the effect of pqsR gene on Plt biosynthesis, the dynamic curves of Plt production by strains M18 and M18PRG was measured in KMB media. As a result, Plt production of the pqsR mutant was three to four folds higher than that of its parent strain M18. The Plt production was restored to the wild-type level when strain M18PRG was complemented with pqsR gene in trans. The regulation of pqsR gene on Plt production was further confirmed by the pltA′-′lacZ translational fusion analysis. These results indicate that pqsR gene negatively controls the Plt biosynthesis. Additionally, by analyzing the growth curves of wild type strain M18 and pqsR mutant, wecan readily find that PqsR has a negative influence on cell growth. It was also shown that the production of red pigments in strain M18 required the expression of pqsR gene. In conclusion, the data presented in this study clearly demonstrate that PqsR acts as a global regulator involved in many physiological activities in Pseudomonas sp. M18.

Objective To evaluate the quality of the portal images acquired by computed radiography(CR)system and conventional screen-film system,respectively.Methods imaging plates (IP)and X-ray films of a home-devised lead phantom with a leakage of 6.45% were acquired,and modulation transfer function(MTF)curves of the both images were measured using edge method.Portal images of 40 nasopharyngeal cancer patients were acquired by IP and screen-film system respectively.Two doctors with similar experience evaluated the damage degree of petrosa] bone,the receiver operating characteristic(ROC)curve of CR images and general images were drawn according to two doctors evaluation results.Results The identification frequency of CR system and screen-film system were 1.159 and 0.806 Lp/mm respectively.For doctor one,the area under ROC curve of CR images and general images were 0.802 and 0.742 respectively.For doctor two,the area under ROC curve of CR images and general images were 0.751 and 0.600 respectively.The MTF curve and ROC curve of CR are both better than those of screen-film system.Conclusion The image quality of CR portal imaging is much better than that of screen-film system.The utility of CR in linear accelerator for portal imaging is promising in clinic.

OBJECTIVETo investigate the feasibility of dynamic magnetic resonance diffusion tensor imaging (DTI) in rabbit models with implanted VX2 hepatic tumor grafts.

METHODSMRI and DTI images were obtained from 16 rabbit models with implanted VX2 hepatic tumor grafts (14, 18, 22, and 26 days after tumor implantation, respectively) and 4 normal rabbits. The average diffusion coefficient (ADC) and exponential ADC (eADC) were estimated and compared against pathological findings.

RESULTSThe ADC values increased after tumor implantation but then decreased in the rabbit models, whereas eADC exhibited a pattern of reverse changes. These changes significantly differed from those in the control group. Coagulation necrosis and fibrous hyperplasia showed obvious increase as found by pathological examination.

CONCLUSIONDynamic MR DTI quantitative analysis of rabbit models of implanted VX2 hepatic tumor can partially describe the growth behaviors of implanted liver cancer.

Animals ; Carcinoma, Hepatocellular ; pathology ; Diffusion Magnetic Resonance Imaging ; Female ; Image Enhancement ; methods ; Liver Neoplasms ; pathology ; Male ; Neoplasm Transplantation ; Rabbits ; Random Allocation

OBJECTIVETo establish New Zealand rabbit hepatoma models with VX2 cell line, and modify the hepatic artery catheterization technique.

METHODSForty New Zealand rabbit models bearing hepatoma were established by implanting VX2 cells into the left and right liver lobes. Two weeks after the tumor cell implantation, 26 rabbits in the experimental group underwent modified hepatic artery catheterization procedures using microsurgical technique, and 10 rabbits in the control group were catheterized with 3F micro-catheter using Seldinger technique. The VX2 hepatomas were observed before and after the catheterization with multi-slice spiral CT scan and digital subtractive angiography (DSA).

RESULTSTumor growth after the tumor cell implantation was confirmed in 36 rabbits by CT scans and open operations. The success rate of catheterization was 88% (23/26) in the experimental group, and 40% (4/10) in the control group. VX2 hepatomas appeared as hypointense or isointense nodules on multi-slice spiral CT, and hepatic artery angiography showed that VX2 hepatomas had homogeneous or nodular tumor staining.

CONCLUSIONThe modified hepatic artery catheterization using microsurgical technique has higher success rate than catheterization with 3F micro-catheter by Seldinger technique, and significantly decreases X-ray exposure for the staff undertaking the operations.

Animals ; Carcinoma, Hepatocellular ; pathology ; Catheterization ; methods ; Cell Line, Tumor ; Disease Models, Animal ; Female ; Hepatic Artery ; Liver Neoplasms, Experimental ; pathology ; Male ; Rabbits ; Radiography, Interventional ; Tomography, Spiral Computed

OBJECTIVETo optimize scan delay time of multi-slice spiral CT portal venography (MSCTP) using test bolus injection.

METHODSSixty individuals with no hepatic diseases were randomly divided into 4 groups (A, B, C and D). The time-density curves (TDC) of the portal vein (PV) were acquired by test bolus (15 ml, 5 ml/s) at the level of liver hilus. In the 4 groups, the MSCTP were delayed for 4, 6, 8 and 10 s according to the peak time of TDC, respectively. The maximum CT value of the portal vein and liver parenchyma were recorded. The maximum intensity projection (MIP) and volume rendering (VR) were employed for three-dimensional reconstruction and the image quality of the 4 groups was estimated.

RESULTSThe average peak time of healthy individuals ranged between 24 and 32 s (95% confidence interval) by means of the test bolus (15 ml). Group C (delay time of 8 s) had a much better image quality of the portal vain than the other groups, and the small branches of the portal vein (6th and 7th orders) were clearly visualized; the major portal vein branches (1st to 4th orders) were also enhanced with sharp edges. Although the hepatic vein was also observed in the portal venous phase in group D, the details of the portal vein on the hepatic edge were distinct and well defined.

CONCLUSIONAt the injection rate of 5 ml/s, the optimum scan time delayed is 8 to 10 s in normal individuals according to the peak time of the test bolus.

Adult ; Aged ; Female ; Humans ; Male ; Middle Aged ; Phlebography ; methods ; Portal Vein ; diagnostic imaging ; Reproducibility of Results ; Time Factors ; Tomography, Spiral Computed ; methods ; Young Adult

Objective To study the vascular compression on the ponline cistern of the trigeminal with magnetic resonance diffusion tensor imaging (DTI) and explore the clinical application value of DTI.Methods Sixty patients who were conformed by operation as having trigeminal neuralgia (TN) caused by responsible vascular compression (TN group) and 50 healthy volunteers (control group) were performed conventional MRI and horizontal DTI to measure the apparent diffusion coefficient (ADC)value and fractional anisotropy (FA) value. Results The ADC value and FA value of trigeminal nerve in control group were (1.76±0.98)×10-3 mm2/s, and (0.40±18), respectively, no significant differences of the ADC value and FA value between the left and right trigeminal nerves were found (P>0.05). The ADC and FA values of the trigeminal nerve among the controls, patients with mild or severe compression and the patients with compression combined with neuratrophia were statistically difrerent(P<0.05). The ADC value in the oppression region was increased in 28 patients and unchanged in 4; the average ADC value in the NT group was significantly higher than that in the control group. FA value in the oppression region decreased in 15 patients, unchanged in11 and increased in 5; the average FA value in the NT group was lower than that in the control group. Conclusion DTI has its value in determining the vascular compression of the trigeminal nerve; the greater the degree of trigeminal nerve compression is, the higher the ADC value and the lower the FA value are.

Objective To evaluate the value of 3.0T susceptibility-weighted magnetic resonance imaging (SWI) in the diagnosis of cerebrovascular malformations. Methods Forty-six patients with cerebrovascular malformations, admitted to our hospital fiom May 2008 to December 2010, were examined with a 3.0T MR scanner. All patients were examined with MRI conventional sequences T1WI,T2WI, 3DTOF, and their results were compared with SWI sequence so as to evaluate the value of SWI in the diagnosis of cerebrovascular malformations.Results Twenty-five patients had arteriovenous malformation (AVM), 10 with cavernous hemangioma, 8 with venous malformations, and 3 with telangiectasis in the 46 patients with cerebrovascular malformations. SWI could delineate all the cerebrovascular malformation lesions, especially small lesions, but could not display all supplying artery in AVM. 3DTOF was a better technique in delineating large AVM lesions. Conclusion SWI is much more sensitive in showing small cerebrovascular malformations; and combined with other MR sequences,clear diagnosis of cerebral vascular malformations can be made by SWI.

OBJECTIVETo study the segmentation methods of the liver CT images and the value of 3-dimensional (3D) reconstruction of the liver in the planning of hepatic surgery.

METHODSThe 2D Digital Imaging and Communications in Medicine (DICOM) format data of the liver obtained from healthy volunteers were transformed into bmp format image, and the liver image segmentation was performed using Photoshop software. The 3D model was reconstructed using MIMICS software.

RESULTSThe DICOM format data of the liver obtained by 64 slice spiral CT included totally 658 slice images. The segmented liver image showed clear profiles and complete intrahepatic duct data were reserved. The segmented liver images were free of discontinuation during continuous observation. The liver surface and internal ductal system, including the hepatic arteries and veins, and the hepatic portal system and their branches, were represented clearly. The reconstructed liver allowed clear identification of the anatomic landmark and matched the actual liver volume. The reconstructed ductal structure were distinct and continuous with natural texture. The reconstructed liver and the hepatic internal duct system were simultaneously displayed by adjusting the transparency of the liver, and the blood vessels were also represented.

CONCLUSIONSegmentation of the liver images in different phases using Photoshop can be feasible for liver reconstruction. The reconstructed liver and the intrahepatic ductal structure allow vivid 3D observation of the spatial relationship among the major tracts and accurate estimation of the liver volume.

Adult ; Female ; Humans ; Image Interpretation, Computer-Assisted ; methods ; Image Processing, Computer-Assisted ; methods ; Imaging, Three-Dimensional ; methods ; Liver ; diagnostic imaging ; Tomography, Spiral Computed ; methods

OBJECTIVETo investigate the possibility of dynamic magnetic resonance (MR) perfusion-weighted imaging (PWI) in rabbit models of implanted hepatic VX2 tumor.

METHODSMRI and PWI images were obtained from 16 rabbit models of implanted hepatic VX2 tumor and 4 normal rabbits at 14, 18, 22, and 26 days after tumor implantation, respectively, and the mean time to enhancement (MTE) and maximum slope of increase (MSI) were estimated and compared with pathological changes.

RESULTSIn the rabbit models of implanted hepatic tumor the MTE tended to increase and MSI to descend 14, 18, 22, and 26 days after tumor implantation, showing significant differences from the control group. Coagulation necrosis and fibrous hyperplasia in the tumors appeared to progress with time as found pathologically.

CONCLUSIONDynamic MR PWI quantitative analysis of rabbit models of implanted hepatic VX2 tumor provides valuable means for observing the growth behaviors of VX2 tumor and may be clinically applicable in the evaluation of hepatic diseases.

Animals ; Contrast Media ; administration & dosage ; Female ; Image Interpretation, Computer-Assisted ; methods ; Liver Neoplasms, Experimental ; diagnosis ; Magnetic Resonance Angiography ; methods ; Male ; Rabbits ; Random Allocation

Objective To study the MRI appearance and clinical features of dysembryoplastic neuroepithelial tumor (DNT) to improve accurate diagnosis of DNT. Methods The clinical data and MRI appearance of 12 patients with DNT confirmed by surgery and pathology were analyzed retrospectively. Routine MRI was performed in all of the 12 patients, and also dynamic contrast-enhanced MR imaging in 10 of them. Results Eight lesions resided in the temporal lobes, 2in the frontal lobe, and the other 2 in the parietal lobe. All of the 12 DNTs located in supratentorial hemisphere cortex, and 6 of them encroached the adjacent white matter. The lesions appeared as hypointense or iso-hypointense signal on T1WI of MRI, and hyperintense on T2WI and FLAIR of MRI.Cystic structure was shown in all the lesions or as its main part, and mesh-separated structure was also noted in some of the tumors. Five lesions appeared as a triangle in shape, 5 in gyrus-like shape and the remaining 2 in round shape. All the tumors had no significant mass effect with 1 having mild edema around the tumor. Enhanced MR imaging showed only 1 lesion having slight and heterogeneous enhancement. Conclusion DNT is accorded with general tumor's biological characteristics. MRI has great value on DNT's diagnosis. If a cystic lesion locates in the hemisphere cortex with a triangle in shape or gyrus-like shape, having no significant mass effect and peripheral edema, it has a great possibility of being DNT.