BackgroundPersistent cognitive impairment is prevalent among patients with stable schizophrenia. While serum total bile acid （TBA） level in acute-phase patients are known to be associated with cognitive dysfunction， the relationship between serum TBA and multi-dimensional cognitive functions in stable phase patients remains unclear. ObjectiveTo investigate the correlation between serum TBA level and cognitive function in patients with stable schizophrenia， and to evaluate its predictive value for cognitive impairment， thereby providing a serological biomarker for the timely identification and objective assessment of cognitive dysfunction. MethodsA cross-sectional study was conducted on 137 inpatients with stable schizophrenia at The Fourth People's Hospital of Yancheng from March to December 2024. All participants met the diagnostic criteria of the Diagnostic and Statistical Manual of Mental Disorders， fifth edition （DSM-5）. Cognitive function was evaluated using the Chinese Brief Cognitive Test （C-BCT）， patients were categorized into four groups： normal cognition （n=28）， mild impairment （n=28）， moderate impairment （n=47）， and severe impairment （n=34）. Fasting venous blood samples were collected， and serum TBA level was quantified using an enzymatic cycle assay. Spearman correlation analysis was ultilized to determine the relationship between serum TBA level， overall cognitive function， and specific cognitive domains. Binary Logistic regression model was used （adjusting for covariates such as age， gender， and disease duration） to analyze the impact of serum TBA level on overall and individual cognitive functions. The predictive value of serum TBA level for overall cognitive impairment was evaluated using receiver operating characteristic （ROC） curve. ResultsSerum TBA levels differed significantly among the four groups （H=18.677， P<0.01）. Specifically， serum TBA levels in both the moderate and severe cognitive impairment groups were significantly higher than those in the normal cognitive group （adjusted P<0.01）. Serum TBA level was positively correlated with the severity grading of overall cognitive impairment （r_s=0.354， P<0.05）， and negatively correlated with T-scores on the trail making test （r_s=-0.328， P<0.05）， continuous performance test （r_s=-0.247， P<0.05）， digit span （r_s=-0.265， P<0.05）， and symbol coding （r_s=-0.221， P<0.05）. Binary Logistic regression analysis identified serum TBA level as an independent risk factor for overall cognitive impairment （OR=1.322， 95% CI： 1.021 - 1.713， P=0.034）， with a particularly robust predictive ability for impaired information processing speed （OR=1.325， 95% CI： 1.057 - 1.661， P=0.015）. The area under ROC curve （AUC） for serum TBA level in predicting overall cognitive impairment was 0.738， with a sensitivity of 60.61% and a specificity of 78.64%. ConclusionIn patients with stable schizophrenia， elevated serum TBA levels are associated with worse overall cognitive function， as well as deficits in information processing speed， attention， working memory， and executive function. Serum TBA serves as an independent risk factor and exhibits moderate predictive value for overall cognitive impairmen，particularly in the domain of information processing speed. ［Funded by Yancheng Municipal Health Commission Medical Research Project （number， YK2024141）］

Objective:To evaluate the survival benefit of surgical treatment for intrahepatic cholangiocarcinoma.Methods:This study is conducted based on the hepatobiliary tumor registry database. From May 2009 to December 2022,a total of 704 patients who were initially diagnosed with intrahepatic cholangiocarcinoma and underwent liver resection were consecutively enrolled at the Hepatobiliary Center of the First Affiliated Hospital of Nanjing Medical University. Among them,there were 380 males and 324 females,aged ( M(IQR)) 61(15) years(range:27 to 88 years). Twenty-six (3.7%) patients received neoadjuvant therapy before surgery. The overall survival(OS) and disease-free survival(DFS) rates were estimated by life table method, and Kaplan-Meier survival curves were plotted. Log-rank test was used to compare the survival difference among tumor-node-metastasis(TNM) staging or three periods. The OS and DFS differences among lymph node groups or adjuvant treatment groups were quantified as HR with 95% CI estimated using Cox proportional-hazards model with adjustment for prognostic factors. Results:Among the 704 patients,349 cases(49.6%) underwent major hepatectomy (≥3 segments),331(47.0%) had lymph node resection during surgery,and 524 cases(74.4%) achieved R0 resection. The morbidity of Clavien-Dindo grade Ⅲ or higher complications was 16.5%(116/704),with a mortality rate of 3.0%(21/704) within 30 days post-surgery. The median OS time was 27.1 months, and the OS rates at 1-,3-,5- and 10-year were 69.1%, 42.4%,34.1% and 24.5%,respectively. The median DFS time was 10.5 months,and the corresponding DFS rates were 46.0%,25.4%,21.9% and 16.9%,respectively. According to the 8 th edition of AJCC staging system, the 5-year survival rates for ⅠA,ⅠB,Ⅱ,ⅢA,ⅢB and Ⅳ were 68.4%, 43.2%, 30.3%,32.2%,14.0% and 0,respectively. The corresponding DFS rates were 55.8%, 28.1%,13.8%,21.2%,3.3% and 0,respectively. There were no statistically significant differences of OS or DFS between stage ⅠB and Ⅱ, stage ⅠB and ⅢA, or between stage Ⅱ and ⅢA(Log-rank test:all P>0.05),while there were significant differences of OS and DFS among other stages(Log-rank test:all P<0.05). Using Cox model with adjustment for prognostic factors, there were no statistically significant differences of OS and DFS between non-lymphadenectomy group or the biopsy-N0 group and dissection-N0 group(both P>0.05). However,the overall and disease-free survival of the biopsy-N1 group or dissection-N1 group were worse than those of dissection-N0 group(both P<0.05),with overall survival being better in dissection-N1 group than biopsy-N1 group( P=0.017). Overall survival in the period from 2019 to 2022 were significantly superior to that during the periods from 2009 to 2013 and 2014 to 2018(both P<0.01). Adjusting for prognostic factors, the disease-free and overall survival of the postoperative adjuvant therapy group were significantly better than those of the observation group in the period 2019 to 2022(both P<0.01). Conclusions:Surgery remains a milestone for achieving long-term survival for patients with intrahepatic cholangiocarcinoma. Regional lymph node dissection is required for patients with lymph node metastasis. Adjuvant therapy can significantly reduce tumor recurrence and prolong overall survival.

Objective:To evaluate the survival benefit of surgical treatment for intrahepatic cholangiocarcinoma.Methods:This study is conducted based on the hepatobiliary tumor registry database. From May 2009 to December 2022,a total of 704 patients who were initially diagnosed with intrahepatic cholangiocarcinoma and underwent liver resection were consecutively enrolled at the Hepatobiliary Center of the First Affiliated Hospital of Nanjing Medical University. Among them,there were 380 males and 324 females,aged ( M(IQR)) 61(15) years(range:27 to 88 years). Twenty-six (3.7%) patients received neoadjuvant therapy before surgery. The overall survival(OS) and disease-free survival(DFS) rates were estimated by life table method, and Kaplan-Meier survival curves were plotted. Log-rank test was used to compare the survival difference among tumor-node-metastasis(TNM) staging or three periods. The OS and DFS differences among lymph node groups or adjuvant treatment groups were quantified as HR with 95% CI estimated using Cox proportional-hazards model with adjustment for prognostic factors. Results:Among the 704 patients,349 cases(49.6%) underwent major hepatectomy (≥3 segments),331(47.0%) had lymph node resection during surgery,and 524 cases(74.4%) achieved R0 resection. The morbidity of Clavien-Dindo grade Ⅲ or higher complications was 16.5%(116/704),with a mortality rate of 3.0%(21/704) within 30 days post-surgery. The median OS time was 27.1 months, and the OS rates at 1-,3-,5- and 10-year were 69.1%, 42.4%,34.1% and 24.5%,respectively. The median DFS time was 10.5 months,and the corresponding DFS rates were 46.0%,25.4%,21.9% and 16.9%,respectively. According to the 8 th edition of AJCC staging system, the 5-year survival rates for ⅠA,ⅠB,Ⅱ,ⅢA,ⅢB and Ⅳ were 68.4%, 43.2%, 30.3%,32.2%,14.0% and 0,respectively. The corresponding DFS rates were 55.8%, 28.1%,13.8%,21.2%,3.3% and 0,respectively. There were no statistically significant differences of OS or DFS between stage ⅠB and Ⅱ, stage ⅠB and ⅢA, or between stage Ⅱ and ⅢA(Log-rank test:all P>0.05),while there were significant differences of OS and DFS among other stages(Log-rank test:all P<0.05). Using Cox model with adjustment for prognostic factors, there were no statistically significant differences of OS and DFS between non-lymphadenectomy group or the biopsy-N0 group and dissection-N0 group(both P>0.05). However,the overall and disease-free survival of the biopsy-N1 group or dissection-N1 group were worse than those of dissection-N0 group(both P<0.05),with overall survival being better in dissection-N1 group than biopsy-N1 group( P=0.017). Overall survival in the period from 2019 to 2022 were significantly superior to that during the periods from 2009 to 2013 and 2014 to 2018(both P<0.01). Adjusting for prognostic factors, the disease-free and overall survival of the postoperative adjuvant therapy group were significantly better than those of the observation group in the period 2019 to 2022(both P<0.01). Conclusions:Surgery remains a milestone for achieving long-term survival for patients with intrahepatic cholangiocarcinoma. Regional lymph node dissection is required for patients with lymph node metastasis. Adjuvant therapy can significantly reduce tumor recurrence and prolong overall survival.

Background The impact of atmospheric fine particulate matter (PM_2.5) and ozone (O₃) on the mortality of circulatory system diseases cannot be ignored. However, whether the interaction between PM_2.5 and O₃ can affect population health is rarely reported and requires study. Objective To investigate the individual and interactive impacts of atmospheric PM_2.5 and O₃ on the mortality of circulatory system diseases in the population of Ningxia region. Methods The data of 119647 deaths due to circulatory system diseases, daily average concentrations of atmospheric pollutants, and meteorological data in Ningxia from 2013 to 2020 were retrieved. PM_2.5 was divided into low, medium, and high concentrations according to the primary and secondary national limits (35 and 75 μg·m⁻³) of the Ambient air quality standards. Similarly, O₃ was divided into low, medium, and high concentrations according to the national limits (100 and 160 μg·m⁻³). Using a generalized additive mixed model based on quasi Poisson distribution, the impacts of atmospheric PM_2.5 and O₃ as well as their interaction on the mortality of circulatory system diseases were analyzed using the population data of Ningxia region. Results During the target period, males and the ≥ 65 year group accounted for larger proportions of deaths due to circulatory system diseases (55.47% and 79.87% respectively). The daily average concentration of PM_2.5 (40.25 μg·m⁻³) exceeded the national primary limit. In the single pollution model, the highest cumulative lag effects for mortality from circulatory system diseases were PM_2.5 exposure over previous 1 d (lag01) and O₃ exposure for previous 2 d (lag02), and their excess risk (ER) values were 1.03% (95%CI: 0.67%, 1.40%) and 1.02% (95%CI: 0.57%, 1.50%), respectively. The results of concentration stratification analysis showed that the most significant risks of death from circulatory system diseases [ER (95%CI): 1.12% (0.32%, 1.92%) and 0.95% (0.13%, 1.79%) respectively] were found at medium PM_2.5 and O₃ concentrations. The interaction analysis revealed that under, a synergistic effect on the risk of death from circulatory system diseases was identified (relative excess risk due to interaction=3.08%, attributable proportion of interaction=2.90%, synergy index=1.89) when considering the coexistence of PM_2.5 and O₃ above the primary limit. As the concentrations of PM_2.5 and O₃ increased, the synergistic effect increased the risk of death from circulatory system diseases in the general population, men, women, and the ≥ 65 years group. Conclusion Both atmospheric PM_2.5 and O₃ can increase the risk of death from circulatory system diseases, and the two pollutants have a synergistic effect on the risk of death from circulatory system diseases.

Background Long-term exposure to ambient fine particulate matter (PM_2.5) may increase the risk of diabetes, and a healthy diet can effectively control fasting blood glucose levels. However, it is unclear whether dietary factors have a moderating effect on the risk of diabetes associated with atmospheric PM_2.5 exposure. Objective To investigate the association between long-term exposure to PM_2.5 and diabetes in rural areas of Ningxia, and potential interaction of long-term exposure to atmospheric PM_2.5 and diet on diabetes. Methods The study subjects were selected from the baseline survey data of the China Northwest Cohort-Ningxia (CNC-NX) , a natural population cohort. A total of 13917 subjects were included, excluding participants with missing covariate information. We utilized the annual average ambient PM_2.5 concentration from 2014 to 2018 as the long-term exposure level. Logistic regression and multiple linear regression were employed to analyze the associations of long-term atmospheric PM_2.5 exposure with diabetes and fasting blood glucose levels. Stratification by frequency of vegetable consumption, frequency of fruit consumption, and salty taste was used to examine moderating effects on the diabetes risk associated with atmospheric PM_2.5 exposure. Results The mean age of the 13917 subjects was (56.8±10.0) years, and the prevalence of diabetes was 9.8%. Between 2014 and 2018, the average annual concentration of PM_2.5 was (38.10±4.67) μg·m⁻³. The risk (OR) of diabetes was 1.018 (95%CI: 1.005, 1.032) and the fasting blood glucose was increased by 0.011 (95%CI: 0.004, 0.017) mmol·L⁻¹ for each 1 μg·m⁻³ increase in PM_2.5 concentration. Compared to those who consumed vegetables < 1 time per week, individuals who consume vegetables 1-3 times per week and ≥4 times per week had a reduced risk of developing diabetes by 27.1% (OR=0.729, 95%CI: 0.594, 0.893) and 16.8% (OR=0.832, 95%CI: 0.715, 0.971) respectively. Similarly, when compared to those who consumed fruits <1 time per week, individuals who consumed fruits 1-3 times per week and ≥4 times per week exhibited a reduced risk of diabetes by 16.4% (OR=0.836, 95%CI: 0.702, 0.998) and 18.2% (OR=0.818, 95%CI: 0.700, 0.959) respectively. Fasting blood glucose decreased by 0.202 (95%CI: -0.304, -0.101) mmol·L⁻¹ in participants who ate vegetables 1-3 times per week. The effect of salty taste on diabetes and fasting blood glucose was not significant. The results of stratified analysis by dietary factors and PM_2.5 concentration showed that the risks of diabetes were increased in the low PM_2.5 pollution-low vegetable intake frequency group and the high PM_2.5 pollution-low vegetable intake frequency group compared with the low PM_2.5 pollution-high vegetable intake frequency group, with OR values of 3.987 (95%CI: 2.943, 5.371) and 1.433 (95%CI: 1.143, 1.796) respectively. The risk of diabetes was 50.1% higher in participants with high PM_2.5 pollution and low fruit intake frequency than in participants with low PM_2.5 pollution and high fruit intake frequency (OR=1.501, 95%CI: 1.171, 1.926). No interaction was found between salty taste and PM_2.5 on diabetes. Conclusion Long-term exposure to ambient PM_2.5 is associated with an increased fasting blood glucose and an elevated risk of diabetes in rural Ningxia population. Increasing the frequency of weekly consumption of vegetables or fruits may have a certain protective effect against diabetes occurrence, as well as a moderating effect on diabetes and fasting blood glucose levels associated with long-term exposure to atmospheric PM_2.5.

Objective:To analyze the clinical application value of a novel magnetic navigation ultrasound (MNU) combined with digital subtraction angiography (DSA) dual-guided percutaneous transhepatic biliary drainage (PTCD) through the right hepatic duct for the treatment of malignant obstructive jaundice.Methods:Randomized controlled trial. The clinical data of 64 patients with malignant obstructive jaundice requiring PTCD through the right hepatic duct at the Hepatobiliary Center of the First Affiliated Hospital of Nanjing Medical University (Jiangsu Province People′s Hospital) from December 2018 to December 2021 were retrospectively analyzed. The MNU group ( n=32) underwent puncture guided by a novel domestic MNU combined with DSA, and the control group ( n=32) underwent puncture guided by traditional DSA. The operation time, number of punctures, X-ray dose after biliary stenting as shown by DSA, patients' tolerance of the operation, success rate of the operation, pre- and post-operative total bilirubin, and incidence of postoperative complications were compared between the two groups. Results:The operation time of the MNU group was significantly shorter than that of the control group [(17.8±7.3) vs. (31.6±9.9) min, t=-6.35, P=0.001]; the number of punctures in the MNU group was significantly lower [(1.7±0.6) vs. (6.3±3.9) times, t=-6.59, P=0.001]; and the X-ray dose after biliary stenting as shown by DSA in the MNU group was lower than that in the control group [(132±88) vs. (746±187) mGy, t=-16.81, P<0.001]; Five patients in the control group were unable to tolerate the operation, and two stopped the operation, however all patients in the MNU group could tolerate the operation, and all completed the operation, with a success rate of 100% (32/32) in the MNU group compared to 93.8%(30/32) in the control group; the common complications of PTCD were biliary bleeding and infection, and the incidence of biliary bleeding (25.0%, 8/32) and infection (18.8%, 6/32) in the MNU group was significantly lower than that in the control group, 53.1% (17/32) and 28.1% (9/32), respectively. Conclusion:Magnetic navigation ultrasound combined with DSA dual-guided PTCD through the right biliary system for the treatment of malignant obstructive jaundice is safe and feasible.

Iron is an essential trace element for brain development and cognitive function maintenance. Iron homeostasis disruption in the body, whether due to iron overload or deficiency, may lead to a series of adverse consequences to the brain. Vascular cognitive impairment is a neurodegenerative disease characterized by cognitive impairment such as mental decline and weak thinking, which seriously endangers people's health. At present, the relationship between iron metabolism and vascular cognitive impairment is receiving more and more attention. This paper summarizes the progress of iron metabolism and its role in vascular cognitive impairment, in order to provide new ideas and methods for prevention and treatment of vascular cognitive impairment.

Objective:To investigate the surgical treatment effect and prognostic factors of hilar cholangiocarcinoma.Methods:This is an ambispective cohort study. From August 2005 to December 2022,data of 510 patients who diagnosed with hilar cholangiocarcinoma and underwent surgical resection at the Hepatobiliary Center of the First Affiliated Hospital of Nanjing Medical University were retrospectively collected. In the cohort,there were 324 males and 186 females,with an age of ( M (IQR)) 63(13)years (range:25 to 85 years). The liver function at admission was Child-Pugh A (343 cases,67.3%) and Child-Pugh B (167 cases,32.7%). Three hundred and seventy-two(72.9%) patients had jaundice symptoms and the median total bilirubin was 126.3(197.6) μmol/L(range: 5.4 to 722.8 μmol/L) at admission. Two hundred and fourty-seven cases (48.4%) were treated with percutaneous transhepatic cholangial drainage or endoscopic nasobiliary drainage before operation. The median bilirubin level in the drainage group decreased from 186.4 μmol/L to 85.5 μmol/L before operation. Multivariate Logistic regression was used to identify the influencing factors for R0 resection,and Cox regression was used to construct multivariate prediction models for overall survival(OS) and disease-free survival(DFS). Results:Among 510 patients who underwent surgical resection,Bismuth-Corlett type Ⅲ-Ⅳ patients accounted for 71.8%,among which 86.1% (315/366) underwent hemi-hepatectomy,while 81.9% (118/144) underwent extrahepatic biliary duct resection alone in Bismuch-Corlett type Ⅰ-Ⅱ patients. The median OS time was 22.8 months, and the OS rates at 1-,3-,5-and 10-year were 72.2%,35.6%,24.8% and 11.0%,respectively. The median DFS time was 15.2 months,and the DFS rates was 66.0%,32.4%,20.9% and 11.0%,respectively. The R0 resection rate was 64.5% (329/510), and the OS rates of patients with R0 resection at 1-,3-,5-and 10-year were 82.5%, 48.6%, 34.4%, 15.2%,respectively. The morbidity of Clavien-Dindo grade Ⅲ-Ⅴ complications was 26.1%(133/510) and the 30-day mortality was 4.3% (22/510). Multivariate Logistic regression indicated that Bismuth-Corlett type Ⅰ-Ⅲ ( P=0.009), hemi-hepatectomy and extended resection ( P=0.001),T1 and T2 patients without vascular invasion (T2 vs. T1: OR=1.43 (0.61-3.35), P=0.413;T3 vs. T1: OR=2.57 (1.03-6.41), P=0.010;T4 vs. T1, OR=3.77 (1.37-10.38), P<0.01) were more likely to obtain R0 resection. Preoperative bilirubin,Child-Pugh grade,tumor size,surgical margin,T stage,N stage,nerve infiltration and Edmondson grade were independent prognostic factors for OS and DFS of hilar cholangiocarcinoma patients without distant metastasis. Conclusions:Radical surgical resection is necessary to prolong the long-term survival of hilar cholangiocarcinoma patients. Hemi-hepatectomy and extended resection,regional lymph node dissection and combined vascular resection if necessary,can improve R0 resection rate.

Objective:To investigate the surgical treatment effect and prognostic factors of hilar cholangiocarcinoma.Methods:This is an ambispective cohort study. From August 2005 to December 2022,data of 510 patients who diagnosed with hilar cholangiocarcinoma and underwent surgical resection at the Hepatobiliary Center of the First Affiliated Hospital of Nanjing Medical University were retrospectively collected. In the cohort,there were 324 males and 186 females,with an age of ( M (IQR)) 63(13)years (range:25 to 85 years). The liver function at admission was Child-Pugh A (343 cases,67.3%) and Child-Pugh B (167 cases,32.7%). Three hundred and seventy-two(72.9%) patients had jaundice symptoms and the median total bilirubin was 126.3(197.6) μmol/L(range: 5.4 to 722.8 μmol/L) at admission. Two hundred and fourty-seven cases (48.4%) were treated with percutaneous transhepatic cholangial drainage or endoscopic nasobiliary drainage before operation. The median bilirubin level in the drainage group decreased from 186.4 μmol/L to 85.5 μmol/L before operation. Multivariate Logistic regression was used to identify the influencing factors for R0 resection,and Cox regression was used to construct multivariate prediction models for overall survival(OS) and disease-free survival(DFS). Results:Among 510 patients who underwent surgical resection,Bismuth-Corlett type Ⅲ-Ⅳ patients accounted for 71.8%,among which 86.1% (315/366) underwent hemi-hepatectomy,while 81.9% (118/144) underwent extrahepatic biliary duct resection alone in Bismuch-Corlett type Ⅰ-Ⅱ patients. The median OS time was 22.8 months, and the OS rates at 1-,3-,5-and 10-year were 72.2%,35.6%,24.8% and 11.0%,respectively. The median DFS time was 15.2 months,and the DFS rates was 66.0%,32.4%,20.9% and 11.0%,respectively. The R0 resection rate was 64.5% (329/510), and the OS rates of patients with R0 resection at 1-,3-,5-and 10-year were 82.5%, 48.6%, 34.4%, 15.2%,respectively. The morbidity of Clavien-Dindo grade Ⅲ-Ⅴ complications was 26.1%(133/510) and the 30-day mortality was 4.3% (22/510). Multivariate Logistic regression indicated that Bismuth-Corlett type Ⅰ-Ⅲ ( P=0.009), hemi-hepatectomy and extended resection ( P=0.001),T1 and T2 patients without vascular invasion (T2 vs. T1: OR=1.43 (0.61-3.35), P=0.413;T3 vs. T1: OR=2.57 (1.03-6.41), P=0.010;T4 vs. T1, OR=3.77 (1.37-10.38), P<0.01) were more likely to obtain R0 resection. Preoperative bilirubin,Child-Pugh grade,tumor size,surgical margin,T stage,N stage,nerve infiltration and Edmondson grade were independent prognostic factors for OS and DFS of hilar cholangiocarcinoma patients without distant metastasis. Conclusions:Radical surgical resection is necessary to prolong the long-term survival of hilar cholangiocarcinoma patients. Hemi-hepatectomy and extended resection,regional lymph node dissection and combined vascular resection if necessary,can improve R0 resection rate.

Human pluripotent stem cells provide an inexhaustible model to study human embryogenesis in vitro. Recent studies have provided diverse models to generate human blastoids by self-organization of different pluripotent stem cells or somatic reprogramming intermediates. However, whether blastoids can be generated from other cell types or whether they can recapitulate postimplantation development in vitro is unknown. Here, we develop a strategy to generate human blastoids from heterogeneous intermediates with epiblast, trophectoderm, and primitive endoderm signatures of the primed-to-naïve conversion process, which resemble natural blastocysts in morphological architecture, composition of cell lineages, transcriptome, and lineage differentiation potential. In addition, these blastoids reflect many features of human peri-implantation and pregastrulation development when further cultured in an in vitro 3D culture system. In summary, our study provides an alternative strategy to generate human blastoids and offers insights into human early embryogenesis by modeling peri- and postimplantation development in vitro.
Humans ; Pluripotent Stem Cells/metabolism* ; Embryo, Mammalian/metabolism* ; Cell Differentiation ; Blastocyst ; Cell Lineage ; Embryonic Development