Objective To elucidate the mechanism of angiotensin (Ang) Ⅱ in regulation of renin synthesis and secretion in primary cultured juxtaglomerular granular cells (JGCs). Methods Mice JGCs were isolated and cultured as described before. Real-time PCR was used to demonstrate the expression of angiotensin converting enzyme (CE) and angiotencin receptor (AT1, AT2) in JGCs. Ang Ⅱ was co-cultured with JGCs stimulated by PGE2 and isoproternol or not. Renin activity in supernatant was detected by radioimmunoassay and renin mRNA expression was examined by real-time PCR. Different concentrations of Ang Ⅱ were co-cultured with JGCs with different time (1 h, 4 h and 24 h), cAMP in cell lysate and supernatant was measured by Cayman Cyclic AMP EIA Kit. The cytoplasmic calcium was decreased by BAPTA-AM, and increased by thapsigargin and cyclopiazonic acid, which could be used to observe the cAMP concentration affected by calcium. Adenylyl cyclase type 5, 6 (AC5, AC6) mRNA expression of JGCs co-cultured with Ang Ⅱ was measured by real-time PCR. Results Real-time PCR confirmed the expression of ACE and AT mRNA in JGCs of WT mice. Angiotensin Ⅱ reduced renin secretion in primary cultures of JGCs [(370.6±36.9) vs (299.6±25.7) ng AngI'ml~(-1)·h~(-1), P=0.014]. Angiotensin Ⅱ dose-dependently down-regulated forskolin-stimulated cAMP production in JGCs. Thapsigargin and cyclopiazonic acid decreased cAMP level. BAPTA-AM increased cAMP production obviously [(11.09±0.48) vs (3.55±0.47) nmol/L, P<0.01]. Ang Ⅱ inhibited AC5 mRNA expression by 42.12%, but did not inhibit AC6 mRNA expression. Conclusions Angiotensin Ⅱ can directly inhibit renin synthesis and secrestion maybe through reducing AC-stimulated cAMP levels. Crosstalk between calcium and cAMP system may exist in precise regulation of renin in JGCs.

@@

ObjectiveTo investigate the effect and mechanism of prostaglandin E2 (PGE2) in renin regulation at the juxtaglomerular apparatus (JGA). MethodsMacula densa cell line (MMDD1) was cultured on the special filter. In the medium on the apical lateral of the cells, low concentration of sodium chloride, chloride and different doses of angiotensin Ⅱ (Ang Ⅱ) were used to stimulate the PGE2 secretion. The PGE2 concentration was tested by ELISA. In the animal experiment, the response of plasma renin activity (PRA) to acute intraperitoneal administration of captopril (30 mg/kg) was determined, in conscious wild-type (WT) and cyclooxygenase COX-2-/- mice on C57BL/6 genetic backgrounds. PRA was measured in plasma obtained by tail vein puncture. Different concentrations of PGE2 were used to stimulate the renin secretion of primary cultured JGA cells from COX-2-/- mice and wild type mice. In specific Gsα gene delete mice (low renin producing mice), 24 h urine was collected to test the concentration of PGE2. The COX-2 mRNA and protein of the kidney cortex were observed by real-time PCR and immunohistochemicul staining. ResultsLow chloride could stimulate the PGE2 secretion both at the apical and basement of the macula densa cells. In COX-2-/- mice, the base PRA and were obviously lower than wild type mice. Captopril could stimulate the PRA of (COX)-2-/- mice increasing 32.8 times. But Ang Ⅱ had no effect on PGE2 secretion in macula densa cells. In primary cultured JGA cells, the decreasing renin seretion was partly recovered by PGE2 in cells from COX-2-/- mice. In low renin producing mice, the expression of COX-2 mRNA in the kidney cortex increased by (8.07±1.08) times (n=6, P=0.0022). The COX-2 protein of the kidney cortex and the urine PGE2 increased by several times. ConclusionsLow chloride is the primary stimulation messenger of PGE2 secretion in macula densa cells. The PRA in COX-2-/- mice can be stimulated by angiotensin converting enzyme inhibitor, but the Ang Ⅱ has no direct effect on macula densa cells. When renin production is abolished in JGA cells (Gsα delete mice), COX-2 mRNA and protein up-regulation is observed in kidney cortex and macula densa. PGE2 plays an important role in regulation of renin secretion and renin release in JGA by precise feedback mechanism.

Objective To explore the feasibility of coronary computed tomographic angiography (CCTA) for obese patients with lower tube voltage (100 kV) and lower contrast media concentration (270 mgI/ml) using iterative reconstruction.Methods A total of 48 patients with body mass index greater than 30 kg/m2 were included and randomly divided into 2 groups according to random number table method.The images of the control group were obtained using iodine 370 mgI/ml, a tube voltage of 120 kV, and traditional filtered back projection (FBP) image reconstruction.Patients in the test group were injected with isotonic low concentration contrast media (270 mgI/ml), scanned with a lower tube voltage (100 kV), and adaptive iterative noise reduction image reconstruction algorithm (AIDR-3D) was used.Two experienced physicians scored the image quality in a double-blind way.Independent sample t-test was used to compare the effective dose (E), average CT values, signal to noise ratio (SNR), contrast to noise ratio (CNR), the figure of merit (FOM), image quality scores and the total iodine intake.Side effect was also evaluated.Results The subjective scores for control group and test group were not significantly different (P ＞ 0.05).The scores of two physicians were consistency (Kappa =0.88, P ＜ 0.05).The average CT values, SNR and CNR for the two groups were not significantly different (P ＞ 0.05), but the FOM of the test group was significantly higher than that of the control group (t =-9.250,-8.604,-9.158,-5.341, P ＜ 0.05).Effective dose in the test group was (1.61 ± 0.41) mSv, lower than that of the control group (t =8.373, P ＜ 0.01).The total iodine and iodine injection rate in the test group were both lower than in the control group (t =7.628, 8.480, P ＜ 0.01).The incidence of contrast mediarelated discomfort in the test group was lower than control group (x2 =18.70, 6.25, P ＜ 0.05).Conclusions For obese patients, isotonic low concentration of contrast media and low-dose CCTA could be feasible, which substantially reduce the radiation dose and iodine intake without sacrificing image quality.Trial registration Chinese clinical trial registry, ChiCTR-DPD-15007510.

Objective To investigate the feasibility of low-c oncentration iso_osmolar contrast agent together with low tube voltage and iterative reconstruction algorithm in rabbit liver computed tonography (CT) perfusion imaging.Methods A total of 15 bealthy New Zealand rabbits were scanned twice of liver CT perfusion scans each with 24 hours interval.The first scan (routine group) was acquired at 100 kV and 100 mAs with ultravist (370 mg/ml),while the second (double low group) was acquired at 80 kV and 100 mAs with iodixanol (270 mg/ml) at 24 hours after the first scan.The obtained images were reconstructed with filtered back projection (FBP) and adaptive iterative dose reduction (AIDR-3D)algorithms in the controlled and experimental groups,respectively.The perfusion parameters including hepatic artery perfusion(HAP),portal vein perfasion(PVP),hepatic perfusion index(HPI),and total liver perfusion(TLP) and image quality as image quality score,average CT value of abdomen aorta,signalto-noise ratio(SNR),carrier-to-noise ratio(CNR),and figure of merit(FOM) were compared used pair ttest or Mann-Whitney U-test between the two groups wherever appropriate.The effective radiation dose and iodine intake were also recorded and compared.Results The image quality and perfusion parameters had no significantly different between the two groups except for FOM.The effective radiation dose and iodine intake were 38.79％ and 27.03％ lower in the double low group.Conclusions Low concentration iso _osmolar contrast agent (iodixanol,270 mg/ml) together with low tube voltage (80 kV) helps to reduce radiation dose and iodine intake without compromising perfusion parameters and image quality in liver CT perfusion imaging.

Objective To evaluate the image quality and radiation dose of prospective electrocardiography-triggered coronary 320-slice volume CT angiography with different kV, and the feasibility of coronary scan with ＜ 1 mSv radiation dose.Methods Eighty consecutive patients were randomly divided into two groups equally.The tube voltage according to paradigm was 100 kV in group A and 120 kV in group B.All raw data in group A was reconstructed by the software AIDR in CT system to create a new group named as A1. Such parameters as the mean intraluminal attenuation (SI),noise (SD),signal-to-noise ratio (SNR),contrast-to-noise ratio (CNR),effective radiation dose(E) and image quality score measured in group A were compared with those in group B.The values such as SI,SD,SNR,CNR,image quality scores were compared between group A and group A1.The significance of group B and group A1 was compared in SI,SD,SNR,CNR,image quality scores as well.Results E in group A was significantly lower than that in group B[ E =(0.67 ± 0.18) mSv in group A vs.E =(3.08 ± 1.04) mSv in group B].The value of E in group A was decreased by 78％ compared to group B(t =- 14.30,P＜0.05 ).There was no significant difference in mean image quality scores between two groups(4.57 ± 0.57in groupA vs.4.59 ± 0.59 in group B,t=-1.17,P＞0.05).The values of SI,SD,SNR,CNR in group A were (570.8 ±131.5)HU,25.1 ±6.9,24.5 ±9.1,19.8 ±6.1.And the values of SI,SD,SNR,CNR in group B were (460.6 ± 14.3) HU,15.1 ±3.6,31.7 ±7.7,29.3 ±6.8.The values of SI and SD in group A were significantly higher than those in group B(t =4.49,8.18,P ＜0.05). The values of SNR and CNR in group A were lower than those in group B (t =-4.24,-6.19,P＜0.05).The valuesofS1,SD,SNR,CNR,image quality scores in group Al were (557.9 ±24.5) HU,21.1 ±6.0,27.7±10.0,23.4±7.8,4.60 ± 0.56.There was no difference in the SI and the image quality scores between group A and group A1 ( t =1.09,- 1.90,P ＞ 0.05).Conclusions 320-slice volume CT with 100 kV tube voltage and prospective ECG-triggered technique can reduce the radiation dose to less than 1 mSv and obtain optimal images in diagnosis of coronary arterial diseases.

OBJECTIVETo optimize the experimental model of nitric oxide (NO) production in mouse peritoneal macrophages in response to lipopolysaccharides (LPS) stimulation.

METHODSMouse resident peritoneal macrophages were collected by lavaging the peritoneal cavity of mice with Hank's solution and stimulated with Pseudomonas aeruginosa LPS for NO production. NO concentration in the culture supernatants was measured with Griess Reagent. The influences of cell density, LPS concentration, LPS stimulation duration and culture medium volume on NO production were investigated. Finally, the feasibility of the model was confirmed with specific anti-inflammatory drugs.

RESULTSThe density of macrophages produced the most significant effect on NO production (P<0.001), and optimal results were obtained at the macrophage density of 6×10(6) cells/ml with a volume of 100 µl in each well in 96-well plate. At a LPS concentration below 1 µg/ml, NO production increased proportionally with the increment of LPS concentration (P<0.001), but the increment of NO production declined obviously at LPS concentrations beyond 1 µg/ml, and the peak NO production occurred at a LPS concentration of 10 µg/ml. NO production also increased significantly with the prolongation of LPS stimulation (P<0.05), and the increments were greater within 24-48 h than those in 48-72 h. NO content in the culture supernatant was associated with the medium volume, and the highest level occurred in a system volume of 100 µl. Aspirin (1 mmol/L), dexamethasone (10 µmol/L), and cyclosporin A (10 µmol/L) all significantly inhibited LPS-stimulated production of NO in mouse resident peritoneal macrophages (P<0.001).

CONCLUSIONSMacrophage density, LPS concentration, and the duration of LPS stimulation are the main factors affecting LPS-stimulated NO production in mouse resident peritoneal macrophages. The optimal results can be obtained with a macrophage density of 5×10(6) cells/ml (100 µl per well), LPS concentration of 10 µg/ml, LPS stimulation duration of 24 h or 48 h, and a culture medium volume of 100 to 200 µl.

Animals ; Cells, Cultured ; Female ; Lipopolysaccharides ; pharmacology ; Macrophages, Peritoneal ; drug effects ; secretion ; Male ; Mice ; Mice, Inbred Strains ; Nitric Oxide ; biosynthesis

Objective To compare volar plating and nonoperative treatment for senile comminuted fractures of the distal radius. Methods From October 2012 to June 2015, 46 senile comminuted fractures of the distal radius ( AO types B and C ) were treated surgically or conservatively. Twenty old patients were managed by open reduction and fixation with a volar locked plate. They were 7 men and 13 women, with an average age of 67. 9 ± 10. 7 years, including 7 cases of AO type 23-B and 13 cases of AO type 23-C. Twenty-six patients were managed with closed reduction and plaster cast. They were 8 men and 18 women, with an average age of 66. 2 ± 11. 5 years, including 10 cases of AO type 23-B and 16 cases of AO type 23-C. The 2 groups were compared in terms of follow-up time, union time and wrist functional scores and complica-tions. Results There was no significant difference between the 2 groups in follow-up time ( P > 0. 05 ) . Fractures in the 2 groups all united about 11 weeks after surgery. According to Dienst scoring for reduction, the volar plating group had 13 excellent cases, 4 good ones, 2 fair ones and one poor case, with an excellent to good rate of 85. 0％ while the nonoperative group had 5 excellent cases, 10 good ones, 5 fair ones and 6 poor ones, with an excellent to good rate of 57. 7％. A significant difference was shown between the 2 groups ( P <0. 05 ) . At final follow-ups, the volar plating group had significantly lower Gartland & Werley wrist functional score ( 2. 16 ± 1. 82 ) and complication rate ( 30. 0％, 6/20 ) than the nonoperative group [ 6. 62 ± 3. 78 and 53. 8％( 14/26 ) , respectively ] ( P <0. 05 ) . Conclusion In treatment of senile comminuted fractures of the distal radius, volar locked plating may lead to better functional recovery and fewer complications than nonoper-ative management. However, one should take full account of the physical condition and preference of the patient when surgery is chosen.

Objective To preliminarily analyze the prediction efficiency of multimodal MRI?based radiomics model for preoperative glioma IDH1 gene expression type. Methods The MRI data of 108 surgery?proven glioma patients from May 2015 to January 2019 were retrospectively analyzed, and the MRI data included axial T1WI,T2WI,fluid attenuated inversion recovery (FLAIR),DWI imaging and enhanced T1WI sequence.Forty-seven cases were IDH1 mutant type, and 61 cases were IDH1 wild type. All patients were divided into training and validation groups according to the 7∶3 ratio of the random forest model. Seventy-three cases were in training group, and 35 cases were in validation group. Independent predictors of IDH1 mutation were screened by univariate analysis combined with multivariate logistic regression analysis (P<0.05) in order to construct a random forest diagnosis model of general clinical information and conventional MRI morphological features.General clinical information and conventional MRI morphological features included gender, age, umbers of cases of left and right hemispheres, location of tumors, maximum diameter of tumors, peritumoral edema, intratumoral cystic degeneration, enhancement and ADC value of tumors. The ROI was manually outlined by MaZda software in the most obvious level of 5 sequences of tumor mass and the radiomics features were extracted, including the gray?level co?occurrence matrix(GLCM), the run?length matrix(RUN), the absolute gradient(GRA),the auto?regressive model(ARM) and wavelets transform (WAV). The least absolute shrinkage and selection operator (LASSO)regression were used to select image radiomics features with a method of 10 fold cross?validation and to reduce the dimensions. The screened image radiomics labels were combined with the conventional morphological feature independent predictors to construct a multimodal MRI?based random forest model, and the validation data set was used to evaluate the accuracy and diagnostic efficiency of each model. The sensitivity and specificity of conventional MRI morphological feature model and multimodal MRI?based radiomics prediction model were evaluated dynamically by drawing ROC curves, and the prediction efficiency of the two models was quantified by using AUC statistical indicators. The model classification error rate under different outcomes and the classification error rate of out of bag(OOB)were used to evaluate the stability of the multimodal MRI?based random forest model. The contribution rate of each variable to the model was reflected by the characteristic variables importance assessment map. Results Univariate regression analysis of the conventional MRI morphological characteristics showed that peritumoral edema, cystic degeneration and enhancement were the three independent predictors of IDH1 gene expression (P<0.01). LASSO algorithm and 10?fold cross?validation identified six robust radiomic features including high frequency coefficients of wavelet transform (WavEnHH_s?4) of T2WI, S(4, 4) inverse difference of gray uniformity measurement (InvDfMom), S(5, 0) Entropy (entropy), WavEnHH_s?4 of T1WI enhancement, S(1, 1) InvDfMom, S(1, -1) Entropy Difference (DifEntrp)of Flair.The error rate of classification for different outcomes and classification error rate of random forest OOB data of multimodal MRI radiomics diagnosis model finally stabilized at 10%. The results of Characteristic Variable Importance Assessment Map: Mean Decrease Accuracy and Mean Decrease Gini index were consistent, which showed that besides three conventional MRI morphological predictors peritumoral edema, enhancement and cystic degeneration, the radiomics labels also played a key role in the model. The results of ROC curve showed that the accuracy, specificity,sensitivity and AUC of conventional MRI morphological feature model were 82.7%, 68.4%, 90.9% and 0.835, respectively, and those of multimodal MRI?based radiomics model were 88.5%, 89.5%, 87.8% and 0.956 respectively. Conclusion Multimodal MRI?based radiomics random forest model can improve the predictive efficiency of preoperative glioma IDH1 gene expression type more quantitatively.