Objective To explore the injury types,associated injuries,and correlations of the lateral meniscus posterior root(LMPR),and to improve the comprehensive understanding of LMPR and its associated injuries.Methods The patients with LMPR who underwent knee MRI examination were retrospectively selected.A total of 223 patients with LMPR injury were classified into 4 types.The integ-rity of the meniscofemoral ligament and the grading of the cartilage injuries in the lateral tibiofemoral compartment were recorded.The relationship between the types of LMPR injury and the lateral meniscus tear locations,as well as lateral meniscus extrusion were analyzed.The relationship between the integrity of the meniscofemoral ligament and lateral meniscus extrusion was analyzed.The correlation between the time to clinical presentation after injury and the grading of the cartilage injuries was analyzed in patients with anterior cruciate ligament(ACL)ruptures.Results The incidence of LMPR injury was 1.02％,with males affected 2.19 times more frequently than females.Among patients with ACL ruptures,the incidence was 13.17％.Both type Ⅰ and type Ⅱ LMPR inju-ries predominantly involved only the posterior root,while type Ⅲ injuries mainly affected the posterior root extending to the posterior horn and body.The incidence of the lateral meniscus extrusion was higher in type Ⅲ LMPR injury than in type Ⅱ.When the menis-cofemoral ligament was not intact,the incidence of the lateral meniscus extrusion increased.In patients with ACL ruptures,a longer time to clinical presentation after injury was associated with more severe cartilage injuries grading in the lateral tibiofemoral compart-ment.Conclusion Males are more susceptible to LMPR injuries than females.The classification of LMPR injuries is correlated with the location of the lateral meniscus tears and the incidence of the lateral meniscus extrusion.The integrity of the meniscofemoral lig-ament is related to the incidence of the lateral meniscus extrusion.The time to clinical presentation after injury is related to the sever-ity of cartilage injury in ACL rupture patients.

Objective To explore the ultrasonic cleaning effect and influencing factors of emergency laparoscopic surgical instruments at night.Methods A total of 698 emergency laparoscopic surgical instruments cleaned by ultrasound at night were selected as the research subjects,and the unqualified ultrasonic cleaning of instruments was statistically analyzed.Univariate and multivariate binary Logistic regression equations were used to analyze the factors that may lead to unqualified ultrasonic cleaning.Results Among 698 ultrasonic cleaning sessions for emergency laparoscopic surgical instruments at night,a total of 55 times(7.88%)were unqualified.The results of univariate and multivariate binary Logistic regression analysis showed that the time from cleaning to the end of surgery≥10 hours,luminal surgical instruments,nonstandard pretreatment,unqualified cleaning water quality,and unqualified cleaning medium were the risk factors that lead to the occurrence of unqualified ultrasonic cleaning of emergency laparoscopic surgical instruments at night(OR>1,P<0.05),while manual+ultrasonic cleaning was the protective factor to avoid the occurrence of unqualified ultrasonic cleaning of emergency laparoscopic surgical instruments at night(OR<1,P<0.05).Conclusion The unqualified rate of ultrasonic cleaning of emergency laparoscopic surgical instruments at night is relatively high,so it should be cleaned as early as possible after the surgery.Before ultrasonic cleaning,manual clean-ing should be carried out as much as possible,especially for luminal surgical instruments that are difficult to clean,standardized pretreatment should be carried out,and qualified cleaning water quality and medium should be selected.

This study aims to reveal the effect and mechanism of Gentianella turkestanorum total extract(GTI) in ameliorating non-alcoholic steatohepatitis(NASH). UPLC-Q-TOF-MS was employed to identify the chemical components in GTI. SwissTarget-Prediction, GeneCards, OMIM, and TTD were utilized to screen the targets of GTI components and NASH. The common targets shared by GTI components and NASH were filtered through the STRING database and Cytoscape 3.9.0 to identify core targets, followed by GO and KEGG enrichment analysis. AutoDock was used for molecular docking of key components with core targets. A mouse model of NASH was established with a methionine-choline-deficient high-fat diet. A 4-week drug intervention was conducted, during which mouse weight was monitored, and the liver-to-brain ratio was measured at the end. Hematoxylin-eosin staining, Sirius red staining, and oil red O staining were employed to observe the pathological changes in the liver tissue. The levels of various biomarkers, including aspartate aminotransferase(AST), alanine aminotransferase(ALT), hydroxyproline(HYP), total cholesterol(TC), triglycerides(TG), low-density lipoprotein cholesterol(LDL-C), high-density lipoprotein cholesterol(HDL-C), malondialdehyde(MDA), superoxide dismutase(SOD), and glutathione(GSH), in the serum and liver tissue were determined. RT-qPCR was conducted to measure the mRNA levels of interleukin 1β(IL-1β), interleukin 6(IL-6), tumor necrosis factor α(TNF-α), collagen type I α1 chain(COL1A1), and α-smooth muscle actin(α-SMA). Western blotting was conducted to determine the protein levels of IL-1β, IL-6, TNF-α, and potential drug targets identified through network pharmacology. UPLC-Q-TOF/MS identified 581 chemical components of GTI, and 534 targets of GTI and 1 157 targets of NASH were screened out. The topological analysis of the common targets shared by GTI and NASH identified core targets such as IL-1β, IL-6, protein kinase B(AKT), TNF, and peroxisome proliferator activated receptor gamma(PPARG). GO and KEGG analyses indicated that the ameliorating effect of GTI on NASH was related to inflammatory responses and the phosphoinositide 3-kinase(PI3K)/AKT pathway. The staining results demonstrated that GTI ameliorated hepatocyte vacuolation, swelling, ballooning, and lipid accumulation in NASH mice. Compared with the model group, high doses of GTI reduced the AST, ALT, HYP, TC, and TG levels(P<0.01) while increasing the HDL-C, SOD, and GSH levels(P<0.01). RT-qPCR results showed that GTI down-regulated the mRNA levels of IL-1β, IL-6, TNF-α, COL1A1, and α-SMA(P<0.01). Western blot results indicated that GTI down-regulated the protein levels of IL-1β, IL-6, TNF-α, phosphorylated PI3K(p-PI3K), phosphorylated AKT(p-AKT), phosphorylated inhibitor of nuclear factor kappa B alpha(p-IκBα), and nuclear factor kappa B(NF-κB)(P<0.01). In summary, GTI ameliorates inflammation, dyslipidemia, and oxidative stress associated with NASH by regulating the PI3K/AKT/NF-κB signaling pathway.
Animals ; Non-alcoholic Fatty Liver Disease/genetics* ; Mice ; Network Pharmacology ; Male ; Drugs, Chinese Herbal/administration & dosage* ; Chromatography, High Pressure Liquid ; Liver/metabolism* ; Mice, Inbred C57BL ; Humans ; Mass Spectrometry ; Tumor Necrosis Factor-alpha/metabolism* ; Disease Models, Animal ; Molecular Docking Simulation

Cardiovascular disease (CVD) remains one of the leading causes of mortality among adults globally, with continuously rising morbidity and mortality rates. Metabolic disorders are closely linked to various cardiovascular diseases and play a critical role in their pathogenesis and progression, involving multifaceted mechanisms such as altered substrate utilization, mitochondrial structural and functional dysfunction, and impaired ATP synthesis and transport. In recent years, the potential role of peroxisome proliferator-activated receptors (PPARs) in cardiovascular diseases has garnered significant attention, particularly peroxisome proliferator-activated receptor alpha (PPARα), which is recognized as a highly promising therapeutic target for CVD. PPARα regulates cardiovascular physiological and pathological processes through fatty acid metabolism. As a ligand-activated receptor within the nuclear hormone receptor family, PPARα is highly expressed in multiple organs, including skeletal muscle, liver, intestine, kidney, and heart, where it governs the metabolism of diverse substrates. Functioning as a key transcription factor in maintaining metabolic homeostasis and catalyzing or regulating biochemical reactions, PPARα exerts its cardioprotective effects through multiple pathways: modulating lipid metabolism, participating in cardiac energy metabolism, enhancing insulin sensitivity, suppressing inflammatory responses, improving vascular endothelial function, and inhibiting smooth muscle cell proliferation and migration. These mechanisms collectively reduce the risk of cardiovascular disease development. Thus, PPARα plays a pivotal role in various pathological processes via mechanisms such as lipid metabolism regulation, anti-inflammatory actions, and anti-apoptotic effects. PPARα is activated by binding to natural or synthetic lipophilic ligands, including endogenous fatty acids and their derivatives (e.g., linoleic acid, oleic acid, and arachidonic acid) as well as synthetic peroxisome proliferators. Upon ligand binding, PPARα activates the nuclear receptor retinoid X receptor (RXR), forming a PPARα-RXR heterodimer. This heterodimer, in conjunction with coactivators, undergoes further activation and subsequently binds to peroxisome proliferator response elements (PPREs), thereby regulating the transcription of target genes critical for lipid and glucose homeostasis. Key genes include fatty acid translocase (FAT/CD36), diacylglycerol acyltransferase (DGAT), carnitine palmitoyltransferase I (CPT1), and glucose transporter (GLUT), which are primarily involved in fatty acid uptake, storage, oxidation, and glucose utilization processes. Advancing research on PPARα as a therapeutic target for cardiovascular diseases has underscored its growing clinical significance. Currently, PPARα activators/agonists, such as fibrates (e.g., fenofibrate and bezafibrate) and thiazolidinediones, have been extensively studied in clinical trials for CVD prevention. Traditional PPARα agonists, including fenofibrate and bezafibrate, are widely used in clinical practice to treat hypertriglyceridemia and low high-density lipoprotein cholesterol (HDL-C) levels. These fibrates enhance fatty acid metabolism in the liver and skeletal muscle by activating PPARα, and their cardioprotective effects have been validated in numerous clinical studies. Recent research highlights that fibrates improve insulin resistance, regulate lipid metabolism, correct energy metabolism imbalances, and inhibit the proliferation and migration of vascular smooth muscle and endothelial cells, thereby ameliorating pathological remodeling of the cardiovascular system and reducing blood pressure. Given the substantial attention to PPARα-targeted interventions in both basic research and clinical applications, activating PPARα may serve as a key therapeutic strategy for managing cardiovascular conditions such as myocardial hypertrophy, atherosclerosis, ischemic cardiomyopathy, myocardial infarction, diabetic cardiomyopathy, and heart failure. This review comprehensively examines the regulatory roles of PPARα in cardiovascular diseases and evaluates its clinical application value, aiming to provide a theoretical foundation for further development and utilization of PPARα-related therapies in CVD treatment.

Objective:To explore the clinical characteristics of biliary system diseases complicated by severe acute pancreatitis(SAP) and the risk factors.Methods:This is a retrospective cohort study. A retrospective analysis was conducted on the clinical data of 159 SAP patients admitted to the Department of Pancreatic and Biliary Surgery,the First Affiliated Hospital of Harbin Medical University from January 2019 to October 2024. There were 105 male cases, 54 female cases;aged (42.3±10.8)years (range:20 to 71 years). Grouping was performed according to the presence or absence of concurrent acute acalculous cholecystitis (AAC) and biliary stricture. There were 58 cases in the AAC group,including 40 males and 18 females;aged (43.8±10.6) years (range:28 to 71 years);101 cases in the non-AAC group,including 64 males and 37 females;aged (41.5±10.8) years (range:20 to 64 years);there were statistically significant differences between the two groups in terms of admission total bilirubin,Balthazar-CTSI score,fasting time,and the proportions of concurrent shock and sepsis (all P<0.05);the time from onset of SAP to diagnosis of AAC( M (IQR)) was 10.5 (13.3) days (range: 3 to 34 days). There were 15 cases in the biliary stricture group,including 13 males and 2 females;age (46.5±10.0) years (range:33 to 63 years);141 cases in the non-biliary stricture group,including 89 males and 52 females;age (41.9±10.8) years (range: 20 to 71 years); there were statistically significant differences between the two groups in the proportions of infected pancreatic necrosis,pancreatic head necrosis,and lower extremity venous thrombosis (all P<0.05);the time from the onset of SAP to the diagnosis of biliary stenosis in patients with biliary stenosis was 2.0 (3.0) months (range: 1 to 19 months). Univariate analysis was performed using independent sample t-test, Mann-Whitney U test, χ 2 test,or Fisher′s exact probability method,and variables with P<0.05 in univariate analysis were included in multivariate logistic regression analysis. The receiver operating characteristic (ROC) curve was used to analyze the diagnostic and predictive value of the multivariate logistic regression model for AAC and biliary stricture. Results:There were statistically significant differences in fasting time,Balthazar-CTSI score,admission total bilirubin,and the proportions of concurrent shock and sepsis between the AAC group and non-AAC group ( P<0.05). Multivariate logistic analysis showed that admission total bilirubin ( OR=1.033,95% CI: 1.010 to 1.058, P=0.004),Balthazar-CTSI score ( OR=1.276,95% CI: 1.036 to 1.572, P=0.022),fasting time ( OR=1.127,95% CI: 1.044 to 1.216, P=0.002), and sepsis ( OR=4.033, 95% CI: 1.419 to 11.462, P=0.009) were independent risk factors for AAC complicated by SAP. The area under the curve (AUC) of the ROC curve was 0.820 (95% CI: 0.752 to 0.888). There were statistically significant differences in the proportions of infected pancreatic necrosis,pancreatic head necrosis,and lower extremity venous thrombosis between the biliary stricture group and non-biliary stricture group ( P<0.05). Multivariate logistic analysis showed that infected pancreatic necrosis ( OR=7.376,95% CI:1.566 to 37.750, P=0.012) and pancreatic head necrosis ( OR=3.898,95% CI:1.180 to 12.877, P=0.026) were independent risk factors for biliary stricture complicated by SAP. The AUC of the ROC curve was 0.806 (95% CI:0.715 to 0.898). Conclusions:AAC typically occurs in the early stage of SAP,and biliary stricture usually occurs in the late stage of SAP. Admission total bilirubin,Balthazar-CTSI score,fasting duration,and concurrent sepsis are independent risk factors for AAC complicating SAP. Infected pancreatic necrosis and pancreatic head necrosis are independent risk factors for biliary stricture complicating SAP.

Objective:To explore the clinical characteristics of biliary system diseases complicated by severe acute pancreatitis(SAP) and the risk factors.Methods:This is a retrospective cohort study. A retrospective analysis was conducted on the clinical data of 159 SAP patients admitted to the Department of Pancreatic and Biliary Surgery,the First Affiliated Hospital of Harbin Medical University from January 2019 to October 2024. There were 105 male cases, 54 female cases;aged (42.3±10.8)years (range:20 to 71 years). Grouping was performed according to the presence or absence of concurrent acute acalculous cholecystitis (AAC) and biliary stricture. There were 58 cases in the AAC group,including 40 males and 18 females;aged (43.8±10.6) years (range:28 to 71 years);101 cases in the non-AAC group,including 64 males and 37 females;aged (41.5±10.8) years (range:20 to 64 years);there were statistically significant differences between the two groups in terms of admission total bilirubin,Balthazar-CTSI score,fasting time,and the proportions of concurrent shock and sepsis (all P<0.05);the time from onset of SAP to diagnosis of AAC( M (IQR)) was 10.5 (13.3) days (range: 3 to 34 days). There were 15 cases in the biliary stricture group,including 13 males and 2 females;age (46.5±10.0) years (range:33 to 63 years);141 cases in the non-biliary stricture group,including 89 males and 52 females;age (41.9±10.8) years (range: 20 to 71 years); there were statistically significant differences between the two groups in the proportions of infected pancreatic necrosis,pancreatic head necrosis,and lower extremity venous thrombosis (all P<0.05);the time from the onset of SAP to the diagnosis of biliary stenosis in patients with biliary stenosis was 2.0 (3.0) months (range: 1 to 19 months). Univariate analysis was performed using independent sample t-test, Mann-Whitney U test, χ 2 test,or Fisher′s exact probability method,and variables with P<0.05 in univariate analysis were included in multivariate logistic regression analysis. The receiver operating characteristic (ROC) curve was used to analyze the diagnostic and predictive value of the multivariate logistic regression model for AAC and biliary stricture. Results:There were statistically significant differences in fasting time,Balthazar-CTSI score,admission total bilirubin,and the proportions of concurrent shock and sepsis between the AAC group and non-AAC group ( P<0.05). Multivariate logistic analysis showed that admission total bilirubin ( OR=1.033,95% CI: 1.010 to 1.058, P=0.004),Balthazar-CTSI score ( OR=1.276,95% CI: 1.036 to 1.572, P=0.022),fasting time ( OR=1.127,95% CI: 1.044 to 1.216, P=0.002), and sepsis ( OR=4.033, 95% CI: 1.419 to 11.462, P=0.009) were independent risk factors for AAC complicated by SAP. The area under the curve (AUC) of the ROC curve was 0.820 (95% CI: 0.752 to 0.888). There were statistically significant differences in the proportions of infected pancreatic necrosis,pancreatic head necrosis,and lower extremity venous thrombosis between the biliary stricture group and non-biliary stricture group ( P<0.05). Multivariate logistic analysis showed that infected pancreatic necrosis ( OR=7.376,95% CI:1.566 to 37.750, P=0.012) and pancreatic head necrosis ( OR=3.898,95% CI:1.180 to 12.877, P=0.026) were independent risk factors for biliary stricture complicated by SAP. The AUC of the ROC curve was 0.806 (95% CI:0.715 to 0.898). Conclusions:AAC typically occurs in the early stage of SAP,and biliary stricture usually occurs in the late stage of SAP. Admission total bilirubin,Balthazar-CTSI score,fasting duration,and concurrent sepsis are independent risk factors for AAC complicating SAP. Infected pancreatic necrosis and pancreatic head necrosis are independent risk factors for biliary stricture complicating SAP.

Objective To explore the injury types,associated injuries,and correlations of the lateral meniscus posterior root(LMPR),and to improve the comprehensive understanding of LMPR and its associated injuries.Methods The patients with LMPR who underwent knee MRI examination were retrospectively selected.A total of 223 patients with LMPR injury were classified into 4 types.The integ-rity of the meniscofemoral ligament and the grading of the cartilage injuries in the lateral tibiofemoral compartment were recorded.The relationship between the types of LMPR injury and the lateral meniscus tear locations,as well as lateral meniscus extrusion were analyzed.The relationship between the integrity of the meniscofemoral ligament and lateral meniscus extrusion was analyzed.The correlation between the time to clinical presentation after injury and the grading of the cartilage injuries was analyzed in patients with anterior cruciate ligament(ACL)ruptures.Results The incidence of LMPR injury was 1.02％,with males affected 2.19 times more frequently than females.Among patients with ACL ruptures,the incidence was 13.17％.Both type Ⅰ and type Ⅱ LMPR inju-ries predominantly involved only the posterior root,while type Ⅲ injuries mainly affected the posterior root extending to the posterior horn and body.The incidence of the lateral meniscus extrusion was higher in type Ⅲ LMPR injury than in type Ⅱ.When the menis-cofemoral ligament was not intact,the incidence of the lateral meniscus extrusion increased.In patients with ACL ruptures,a longer time to clinical presentation after injury was associated with more severe cartilage injuries grading in the lateral tibiofemoral compart-ment.Conclusion Males are more susceptible to LMPR injuries than females.The classification of LMPR injuries is correlated with the location of the lateral meniscus tears and the incidence of the lateral meniscus extrusion.The integrity of the meniscofemoral lig-ament is related to the incidence of the lateral meniscus extrusion.The time to clinical presentation after injury is related to the sever-ity of cartilage injury in ACL rupture patients.

Objective To explore the ultrasonic cleaning effect and influencing factors of emergency laparoscopic surgical instruments at night.Methods A total of 698 emergency laparoscopic surgical instruments cleaned by ultrasound at night were selected as the research subjects,and the unqualified ultrasonic cleaning of instruments was statistically analyzed.Univariate and multivariate binary Logistic regression equations were used to analyze the factors that may lead to unqualified ultrasonic cleaning.Results Among 698 ultrasonic cleaning sessions for emergency laparoscopic surgical instruments at night,a total of 55 times(7.88%)were unqualified.The results of univariate and multivariate binary Logistic regression analysis showed that the time from cleaning to the end of surgery≥10 hours,luminal surgical instruments,nonstandard pretreatment,unqualified cleaning water quality,and unqualified cleaning medium were the risk factors that lead to the occurrence of unqualified ultrasonic cleaning of emergency laparoscopic surgical instruments at night(OR>1,P<0.05),while manual+ultrasonic cleaning was the protective factor to avoid the occurrence of unqualified ultrasonic cleaning of emergency laparoscopic surgical instruments at night(OR<1,P<0.05).Conclusion The unqualified rate of ultrasonic cleaning of emergency laparoscopic surgical instruments at night is relatively high,so it should be cleaned as early as possible after the surgery.Before ultrasonic cleaning,manual clean-ing should be carried out as much as possible,especially for luminal surgical instruments that are difficult to clean,standardized pretreatment should be carried out,and qualified cleaning water quality and medium should be selected.

AIM To study the amino acids and proteins in 16 batches of commercial fish swim-bladders with different origins.METHODS A high performance liquid chromatography method based on pre-column derivatization using 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate(AQC)was developed for the determination of contents and components of 17 amino acids in fish swim-bladders.Sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE)was performed to analyze the molecular weight distribution of proteins from different fish swim-bladders,and proteins in fish swim-bladders were identified by proteomics method.RESULTS The result showed that the determination of 17 amino acids had a good linear relationship(R2≥0.998 0).The average recovery rate was 85.62%-109.60%and the relative standard deviations of precision,stability and repeatability were less than 3.5%.The total content of the 17 amino acids in 16 batches of fish swim-bladders ranged from 468.31 mg/g to 620.05 mg/g.A total of 688 proteins including 11 collagens were identified from 16 batches of fish swim-bladder samples and a plenty of low-abundance proteins at 52-95 kDa were also detected in fish swim-bladders by SDS-PAGE.CONCLUSION This study provides a good reference for the quality evaluation and further utilization of fish swim-bladders.

Objective:To perform harmonization based on the ComBat method for PET brain imaging scanned by different types of scanners from the same manufacturer and explored its effect on center effect.Methods:The three-dimensional (3D) Hoffman brain model was scanned by two different PET/CT instruments (Siemens Biograph64 TruePoint and Biograph128 mCT). Fourteen healthy subjects (8 males, 6 females, age: (57.7±9.5) years) underwent 18F-FDG PET/CT on Siemens Biograph64 TruePoint and 12 healthy subjects (9 males, 3 females, age: (55.8±10.5) years) underwent 18F-FDG PET/CT on Siemens Biograph128 mCT (all from Huashan Hospital, Fudan University; from November 2020 to March 2023). The whole brain was divided into 116 brain regions based on the anatomical automatic labeling (AAL) brain template. The ComBat method was applied to harmonized the PET data from brain model and healthy subjects. Mann-Whitney U test was performed on the radioactive counts and SUV ratios (SUVR) before and after homogenization acquired by both PET/CT instruments. Voxel-based statistical parametric mapping (SPM) independent-sample t test was also performed on data of healthy subjects. Results:In 3D Hoffman brain model, radioactivity counts (5 590.33(4 961.67, 6 102.95) vs 6 116.03(5 420.97, 6 660.66); z=-9.35, P<0.001) and SUVR (1.35(1.19, 1.47) vs 1.37(1.21, 1.49); z=-3.63, P<0.001) were significantly different between the two PET/CT scanners before harmonization and not after harmonization (radioactivity counts: 5 845.95(5 192.68, 6 378.63) vs 5 859.17(5 193.84, 6 380.52); SUVR: 1.35(1.20, 1.48) vs 1.36(1.20, 1.49); both z=-0.68, both P=0.498). In the healthy subjects, radioactive counts in 19 brain regions (12 422.78(11 181.60, 13 424.28)-18 166.40(15 882.80, 18 666.27); z values: from -3.24 to -2.06, all P<0.05) and SUVR in 40 brain regions (1.46(1.41, 1.52)-2.28(2.16, 2.36); z values: from -3.65 to -1.70, all P<0.05) were significantly different between the two scanners before harmonization, while after homogenization there were no statistical differences for all 116 brain regions (radioactivity counts: 9 243.55(8 502.38, 9 854.87)-20 419.60(19 931.51, 21 179.43); z values: from -0.72 to 0, all P>0.05; SUVR: 1.04(1.01, 1.09)-2.32(2.24, 2.40); z values: from -0.82 to 0, all P>0.05). SPM showed that significant differences of glucose metabolism in the cerebral cortex, basal ganglia, midbrain and cerebellum were found in healthy subjects between the two PET/CT scanners before homogenization, and brain regions with obvious differences reduced after homogenization. Conclusion:ComBat harmonization method is efficient at removing the center effect among different types of PET/CT scanners from the same manufacturer and may provide a simple and easy-to-implement homogenization for multicenter brain imaging studies.