A Decade of Scientific and Technological Innovation at Chinese Academy of Medical Sciences & Peking Union Medical College: Retrospect and Prospect.

Focusing on the reform initiatives of Chinese Academy of Medical Sciences (CAMS) & Peking Union Medical College (PUMC) in medical scientific and technological innovation from perspectives of deepening the reform and optimizing the ecosystem of science and technology innovation, this article summarizes the highlights of CAMS & PUMC's efforts in safeguarding people's health and promoting the Healthy China 2030 strategy through scientific and technological innovation in the fields including basic research, disease prevention and treatment, and medical technology in the past ten years. These achievements embody the endeavors and responsibility of CAMS & PUMC in realizing self-reliance and self-improvement of Chinese medical science and technology and highlight its contributions to the development of medical science and technology of China.

Quantifying vulnerability to embolism in tropical trees and lianas using five methods: can discrepancies be explained by xylem structural traits?

Vulnerability curves (VCs) describe the loss of hydraulic conductance against increasing xylem tension, providing valuable insights about the response of plant water transport to water stress. Techniques to construct VCs have been developed and modified continuously, but controversies continue. We compared VCs constructed using the bench-top dehydration (BD), air-injection-flow (AI), pneumatic-air-discharge (PAD), optical (OP) and X-ray-computed microtomography (MicroCT) methods for tropical trees and lianas with contrasting vessel lengths. The PAD method generated highly vulnerable VCs, the AI method intermediate VCs, whereas the BD, OP and MicroCT methods produced comparable and more resistant VCs. Vessel-length and diameter accounted for the overestimation ratio of vulnerability estimated using the AI but not the PAD method. Compared with directly measured midday embolism levels, the PAD and AI methods substantially overestimated embolism, whereas the BD, MicroCT and OP methods provided more reasonable estimations. Cut-open vessels, uncertainties in maximum air volume estimations, sample-length effects, tissue cracks and shrinkage together may impede the reliability of the PAD method. In conclusion, we validate the BD, OP and MicroCT methods for tropical plants, whereas the PAD and AI need further mechanistic testing. Therefore, applications of VCs in estimating plant responses to drought need to be cautious.

Deep Sequencing Discovery and Profiling of Known and Novel miRNAs Produced in Response to DNA Damage in Rice.

Under extreme environmental conditions such as ultraviolet and ionizing radiation, plants may suffer DNA damage. If these damages are not repaired accurately and rapidly, they may lead to chromosomal abnormalities or even cell death. Therefore, organisms have evolved various DNA repair mechanisms to cope with DNA damage which include gene transcription and post-translational regulation. MicroRNA (miRNA) is a type of non-coding single-stranded RNA molecule encoded by endogenous genes. They can promote DNA damage repair by regulating target gene transcription. Here, roots from seedlings of the japonica rice cultivar 'Yandao 8' that were treated with bleomycin were collected for transcriptome-level sequencing, using non-treated roots as controls. A total of 14,716,232 and 17,369,981 reads mapping to miRNAs were identified in bleomycin-treated and control groups, respectively, including 513 known and 72 novel miRNAs. Compared with the control group, 150 miRNAs showed differential expression levels. Target predictions of these differentially expressed miRNAs yielded 8731 potential gene targets. KEGG annotation and a gene ontology analysis indicated that the highest-ranked target genes were classified into metabolic processes, RNA degradation, DNA repair, and so on. Notably, the DNA repair process was significantly enriched in both analyses. Among these differentially expressed miRNAs, 58 miRNAs and 41 corresponding potential target genes were predicted to be related to DNA repair. RT-qPCR results confirmed that the expression patterns of 20 selected miRNAs were similar to those from the sequencing results, whereas four miRNAs gave opposite results. The opposing expression patterns of several miRNAs with regards to their target genes relating to the DNA repair process were also validated by RT-qPCR. These findings provide valuable information for further functional studies of miRNA involvement in DNA damage repair in rice.

Prognostic significance of K-ras mutations in pancreatic cancer: a meta-analysis.

BACKGROUND: K-ras gene mutations are common in patients with pancreatic cancer (PC); however, their prognostic value for PC remains inconclusive. This meta-analysis was performed to quantitatively evaluate the association between K-ras mutations and survival in patients with pancreatic cancer. METHODS: We performed a comprehensive search of electronic sources including MEDLINE (via PubMed), Web of Science, and the Cochrane Library. The search covered a publication period from inception to November 2015. RESULTS: Seventeen studies with a total of 2249 patients with pancreatic cancer were included in the tissue detection of this study. The meta-analysis indicated a significant association between mutant K-ras genes and overall survival (OS) (HR = 1.51, 95% CI 1.32-1.72, P < 0.001). Moreover, further subgroup analyses by ethnicity, publication year, therapy method, cancer resectability, and gene detection method all revealed that pancreatic cancer patients with the K-ras mutation had significantly poorer OS (P < 0.05). And results from four studies with 225 patients focused on plasma K-ras mutations enhanced such association (HR = 2.23, 95% CI 1.69-2.95, P < 0.001). CONCLUSIONS: As a prediction of poor prognosis, the detection of K-ras mutations may be a useful prognostic factor for pancreatic cancer patients.

Hydraulic properties and drought response of a tropical bamboo (Cephalostachyum pergracile).

Bamboo plants are an essential component of tropical ecosystems, yet their vulnerability to climate extremes, such as drought, is poorly understood due to limited knowledge of their hydraulic properties. Cephalostachyum pergracile, a commonly used tropical bamboo species, exhibited a substantially higher mortality rate than other co-occurring bamboos during a severe drought event in 2019, but the underlying mechanisms remain unclear. This study investigated the leaf and stem hydraulic traits related to drought responses, including leaf-stem embolism resistance (P50leaf; P50stem) estimated using optical and X-ray microtomography methods, leaf pressure-volume and water-releasing curves. Additionally, we investigated the seasonal water potentials, native embolism level (PLC) and xylem water source using stable isotope. We found that C. pergracile exhibited strong resistance to embolism, showing low P50leaf, P50stem, and turgor loss point, despite its rapid leaf water loss. Interestingly, its leaves displayed greater resistance to embolism than its stem, suggesting a lack of effective hydraulic vulnerability segmentation (HVS) to protect the stem from excessive xylem tension. During the dry season, approximately 49% of the water was absorbed from the upper 20-cm-deep soil layer. Consequently, significant diurnal variation in leaf water potentials and an increase in midday PLC from 5.87 ± 2.33% in the wet season to 12.87 ± 4.09% in the dry season were observed. In summary, this study demonstrated that the rapid leaf water loss, high reliance on surface water, and a lack of effective HVS in C. pergracile accelerated water depletion and increased xylem embolism even in the typical dry season, which may explain its high mortality rate during extreme drought events in 2019.

[Comparison of bowel function pre and post-sigmoid augmentation cystoplasty in spinal cord injury patients].

OBJECTIVE: To explore the changes of bowel function in spinal cord injury (SCI) patients undergoing sigmoid augmentation cystoplasty. METHODS: From September 2005 to January 2011, 30 SCI patients undergoing sigmoid augmentation cystoplasty were surveyed by follow-up questionnaires at Beijing Charity hospital and Affiliated Hospital of Nantong University. RESULTS: Among them, 18 cases (60.0%) believed their defecation became softer and 18 cases (60.0%) thought their defecation time became shorter. The postoperative profiles of patient defecation traits and defecation time were better (P < 0.05), especially traumatic SCI patients (P < 0.05). CONCLUSION: The subtotal resection of sigmoid colon improves the defecation of spinal cord injury patients. The SCI patients undergoing sigmoid augmentation cystoplasty may avoid urinary tract dysfunctions and improve bowel dysfunction.

Prevalences of and risk factors for biliary stones and gallbladder polyps in a large Chinese population.

OBJECTIVES: This study aimed to identify the prevalences of and risk factors associated with the development of gallbladder stones and polyps in a large Chinese population. METHODS: Prevalences of and risk factors for biliary stones and gallbladder polyps were retrospectively investigated among subjects who underwent a general check-up at the Health Screening Centres of Peking Union Medical College Hospital and Beijing Charity Hospital between January 2007 and June 2010. RESULTS: A total of 60,064 people were enrolled in the study. Overall prevalences of biliary stones and gallbladder polyps were 4.2% (n= 2527) and 6.9% (n= 4119), respectively. Risk factors associated with increased odds ratios (ORs) for the development of biliary stones were female gender (OR = 1.51), age ≥ 50 years (OR = 2.09), history of hypertension (OR = 1.37), thickened gallbladder wall (cholecystitis) (OR = 1.98), fasting blood glucose ≥ 6.10 mmol/l (OR = 1.27), body mass index ≥ 25 kg/m(2) (OR = 1.25), systolic blood pressure ≥ 140 mmHg (OR = 1.31) and diastolic blood pressure ≥ 90 mmHg (OR = 1.44). Factors associated with gallbladder polyps were female gender (OR = 0.66), thickened gallbladder wall (OR = 2.09), negativity for hepatitis B surface antigen (HBsAg) and positivity for hepatitis B core antibody (anti-HBc) (OR = 2.61), and positivity for both HBsAg and anti-HBc (OR = 3.21). CONCLUSIONS: Prevalences of biliary stones and gallbladder polyps among Chinese people are similar to those reported for other populations. Biliary stones appear to be associated with female gender, age, obesity, blood glucose, blood pressure and cholecystitis. Male gender, hepatitis B virus infection and cholecystitis were strong risk factors for the formation of gallbladder polyps.

[Metabolism-related risk factors of cholelithiasis among Beijing residents: a case-control study].

OBJECTIVE: To explore the metabolism-related risk factors of cholelithiasis among residents in Beijing. METHODS: The clinical data including previous disease history, findings of physical examination, and results of cholecystosonography of 2270 patients with cholelithiasis identified in the Health Screening Center of Peking Union Medical College Hospital between August 2007 and August 2010 were retrospectively reviewed (the case group). Meanwhile, 4336 healthy individuals during the same period were randomly chosen as the control group. RESULTS: Total cholesterol, triglyceride, low-density lipoprotein cholesterol, fasting blood glucose, body mass index, and systolic blood pressure were positively correlated with the incidence of cholelithiasis (P < 0.05), while high-density lipoprotein cholesterol was negatively correlated (P < 0.05). Diastolic blood pressure showed no association with cholelithiasis (P > 0.05). CONCLUSION: Cholelithiasis is resulted from multiple factors including elevated blood lipids, blood glucose, and systolic blood pressure among residents in Beijing.

Factors Related to Activation in Chinese Patients With Chronic Obstructive Pulmonary Disease: A Cross-Sectional Survey Study.

BACKGROUND: Improving patient activation can lead to better health outcomes among patients with chronic obstructive pulmonary disease (COPD). However, no studies have focused on the issue of activation in patients with COPD in China. PURPOSE: This study was designed to explore the status of activation in patients with COPD in China and explicate the significant influencing factors. METHODS: One hundred seventy patients with COPD were recruited using a convenience sampling method from eight tertiary and secondary hospitals in Nanjing, China. Sociodemographic, clinical, and patient-reported factor data were collected. Univariate analysis and multivariate linear regression were performed. RESULTS: Only 10.6% of the patients were identified as activated for self-management. Multivariate linear regression analysis revealed four explanatory elements as significantly associated with patient activation, including social support (ß = .463, p < .001), free medical insurance (ß = .173, p = .007), smoking status (ß = -.195, p = .002), and health status (ß = -.139, p = .04). CONCLUSIONS/IMPLICATIONS FOR PRACTICE: The findings of this study indicate that a minority of patients with COPD are activated for self-management in China. Having a higher level of patient activation was associated with having better social support, having free medical insurance, being a nonsmoker, and having a better health status. Creating a supportive environment, promoting smoking cessation, and improving medical security and health status may be considered as potential strategies to activate patients into better self-management.

The effects of case management for breast cancer patients: A protocol for systematic review and meta-analysis.

BACKGROUND: Female breast cancer is the most common cancer nowadays, and its treatment has a significant impact on patients both physically and psychologically. Many randomized trials have proved that case management (CM) can effectively care for patients. However, there is a lack of systematic scientific evaluation, so this systematic evaluation aims to explore the impact of CM on breast cancer patients. METHODS: PubMed, Embase, Cochrane Library, Scopus, CINAHL were searched. Chinese repositories included China National Knowledge, Infrastructure Database (CNKI), Wan fang Database, China Biology Medicine Database. We will also search unpublished literature at ClinicalTrials.gov. Randomized controlled trials were collected from them. The literature will be screened according to inclusion and exclusion criteria, and 2 researchers will extract the literature independently. The primary outcome indicator for this study will be patient satisfaction. Statistics were performed using RevMan 5.4 software. The quality of each outcome will be evaluated using the Grading of Recommendations Assessment, Development, and Evaluation. RESULTS: This study will provide the most recent evidence for evaluating the impact of CM on breast cancer patients. CONCLUSION: To evaluate the impact of CM on patients with breast cancer. REGISTRATION NUMBER: DOI:10.17605/OSF.IO/ZJKHX.

Response of four evergreen savanna shrubs to an incidence of extreme drought: high embolism resistance, branch shedding and maintenance of nonstructural carbohydrates.

Extreme drought events are becoming frequent globally, resulting in widespread plant mortality and forest dieback. Although savanna vegetation cover ~20% of the earth's land area, their responses to extreme drought have been less studied than that of forests. Herein, we quantified branch dieback, individual mortality and the associated physiological responses of four evergreen shrubs (Tarenna depauperate Hutch., Maytenus esquirolii (H. Lév.) C.Y. Cheng, Murraya exotica L., Jasminum nudiflorum Lindl.) in a savanna ecosystem in Southwest China to an incidence of extreme drought during 2019 and 2020. We found that 80-100% of the individuals of these species exhibited branch dieback, whereas individual mortality was only found in T. depauperate (4.5%). All species showed high resistance to stem embolism (P50, water potential at 50% loss of hydraulic conductivity ranged from -5.62 to -8.6 MPa), whereas the stem minimum water potentials reached -7.6 to ca -10.0 MPa during the drought. The low water potential caused high native embolism levels (percentage loss of hydraulic conductivity (PLC) 23-65%) in terminal branches, and the remaining stems maintained 15-35% PLC at the end of the drought. Large within-individual variations in stem vulnerability to embolism were detected, and shedding of vulnerable branches could be a mechanism for shrubs to reduce water and carbon consumption. Overall, the content of total nonstructural carbohydrates (NSC) and their components in the stem were generally comparable to or higher than those in the rainy season in three of the four species. Because the leaves were turgor-less for most time during the drought, high NSC levels during the drought could be due to recycling of NSC from dead branches or translocation from roots. Our results suggest high tolerance of savanna shrub species to extreme drought, which could be facilitated by high embolism resistance in some stems and shedding of vulnerable branches to maintain individual water and carbon balance.

Brain Extracellular Space as a Diffusion Barrier.

The extracellular space (ECS) consists of the narrow channels between brain cells together with their geometrical configuration and contents. Despite being only 20-60 nm in width, the ECS typically occupies 20% of the brain volume. Numerous experiments over the last 50 years have established that molecules moving through the ECS obey the laws of diffusion but with an effective diffusion coefficient reduced by a factor of about 2.6 compared to free diffusion. This review considers the origins of the diffusion barrier arising from the ECS and its properties. The paper presents a brief overview of software for implementing two point-source paradigms for measurements of localized diffusion properties: the real-time iontophoresis or pressure method for small ions and the integrative optical imaging method for macromolecules. Selected results are presented. This is followed by a discussion of the application of the MCell Monte Carlo simulation program to determining the importance of geometrical constraints, especially dead-space microdomains, and the possible role of interaction with the extracellular matrix. It is concluded that we can predict the impediment to diffusion of many molecules of practical importance and also use studies of the diffusion of selected molecular probes to reveal the barrier properties of the ECS.

Transcriptome analysis of ovary culture-induced embryogenesis in cucumber (Cucumis sativus L.).

BACKGROUND: Ovary culture is a useful technique used to generate double haploid (DH) cucumber (Cucumis sativus L.) plants. However, cucumber ovary culture have a low rate of embryo induction and plant regeneration. Moreover, the cucumber embryogenesis mechanism remains unclear. In this study, we explored the molecular basis of cucumber embryogenesis in order to establish a foundation for a more efficient ovary culture method. Using transcriptome sequencing, we also investigated the differential expression of genes during the embryogenesis process. METHODS: Cytological and morphological observations have divided cucumber ovary culture into three stages: early embryo development (T0), embryo morphogenesis (T1, T2, T3 and T4), and shoot formation (T5). We selected six key time points for transcriptome sequencing and analysis: T0 (the ovules were cultured for 0 d), T1 (the ovules were cultured for 2 d), T2 (the embryos were cultured for 10 d), T3 (the embryos were cultured for 20 d), T4 (the embryos were cultured for 30 d), and T5 (the shoots after 60 d culture). RESULTS: We used cytology and morphology to observe the characteristics of the cucumber's developmental transformation during embryogenesis and plant regeneration. The differentially expressed genes(DEGs) at developmental transition points were analyzed using transcriptome sequencing. In the early embryogenesis stage, the cells expanded, which was the signal for gametophytes to switch to the sporophyte development pathway. RNA-seq revealed that when compared to the fresh unpollinated ovaries, there were 3,468 up-regulated genes in the embryos, including hormone signal transduction genes, hormone response genes, and stress-induced genes. The reported embryogenesis-related genes BBM, HSP90 and AGL were also actively expressed during this stage. In the embryo morphogenesis stage (from cell division to cotyledon-embryo formation), 480 genes that functioned in protein complex binding, microtubule binding, tetrapyrrole binding, tubulin binding and other microtubule activities were continuously up-regulated during the T1, T2, T3 and T4 time points. This indicated that the cytoskeleton structure was continuously being built and maintained by the action of microtubule-binding proteins and enzyme modification. In the shoot formation stage, 1,383 genes were up-regulated that were mainly enriched in phenylpropanoid biosynthesis, plant hormone signal transduction, phenylalanine metabolism, and starch and sucrose metabolism. These up-regualted genes included six transcription factors that contained a B3 domain, nine genes in the AP2/ERF family, and two genes encoding WUS homologous domain proteins. CONCLUSIONS: Evaluation of molecular gynogenesis events may contribute to a better understanding of the molecular mechanism of cucumber ovarian culture.

Risk factors for intrahepatic and extrahepatic cholangiocarcinoma: a case-control study in China.

BACKGROUND/AIMS: The risk factors for cholangiocarcinoma are incompletely defined in China, especially for intrahepatic cholangiocarcinoma (ICC). We evaluated the risk factors for both ICC and extrahepatic cholangiocarcinoma (ECC). METHODS: A case-control study in which cases were cholangiocarcinoma patients referred to Peking Union Medical College Hospital (PUMCH) between 1998 and 2008 and controls were healthy individuals. Controls were randomly selected from an existing database of healthy individuals at the Health Screening Center of PUMCH. Data on liver disease, family history, diabetes, smoking and drinking were collected by a retrospective review of the patients' records and health examination reports or by interview. RESULTS: A total of 190 patients (61 ICC; 129 ECC) and 380 age- and sex-matched controls were enrolled. HBsAg (P<0.001) and anti-HBc without HBsAg (P=0.001) were significantly related to ICC. The adjusted odds ratios (OR) and 95% confidence intervals (CI) were 18.1 (95% CI: 7.5-44.0) and 3.6 (95% CI: 1.7-7.6) respectively. Diabetes mellitus (P=0.007), cholecystolithiasis (P=0.004) and previous cholecystectomy (P<0.001) were significantly associated with ECC. The prevalence of cirrhosis was higher in ICC than that in ECC (P<0.001). Furthermore, on excluding the ICC patients with cirrhosis, ICC patients showed significant independent associations with HBsAg (OR: 7.3; 95% CI: 3.1-17.2) and anti-HBc without HBsAg (OR: 2.4; 95% CI: 1.1-5.2). CONCLUSION: Cirrhosis and chronic hepatitis B virus infection are risk factors for ICC, while cholecystolithiasis, diabetes and previous cholecystectomy are risk factors for ECC.

Comparison of serum tumor markers for intrahepatic cholangiocarcinoma and hepatocellular carcinoma.

Serum tumor markers such as alpha-fetoprotein (AFP), carcinoembryonic antigen, carbohydrate antigen (CA) 19-9, CA242, and CA50 were analyzed to evaluate their diagnostic values in single and combined tests for distinguishing intrahepatic cholangiocarcinoma (ICC) from hepatocellular carcinoma (HCC). Preoperative serum levels of AFP, carcinoembryonic antigen, CA19-9, CA242, and CA50 were measured in 45 ICC and 76 HCC patients. The serum levels and the positive rate of AFP, CA19-9, and CA242 were significantly different between the ICC patients and HCC patients. Although AFP (-) was the most sensitive assay for distinguishing ICC from HCC (91.1%), its specificity was significantly lower than that of CA242 (+) and CA19-9 (+). The combination of AFP (-) and CA242 (+) afforded a high specificity of 94.3 per cent and showed highest accuracy (78.5%). Evaluation of patients without liver cirrhosis also showed similar results. The diagnostic value of CA242 (+) is better than that of CA19-9 (+) and AFP (-) in distinguishing ICC from HCC. Combined detection of AFP (-) and CA242 (+) can improve the specificity and accuracy of diagnosing ICC.

Gender-specific prognostic markers of patients with gallbladder cancer after surgical resection.

The aim of this study was to elucidate gender-specific markers for postresectional long-term survival of gallbladder cancer (GBC) based on a cohort of Chinese patients. Clinicopathological records of 81 patients (27 males and 54 females) after surgical resection for GBC were reviewed retrospectively. The influence of each variable on survival was determined using the Kaplan-Meier method and log-rank test. For females, Cox regression analysis was also adopted. Univariate analysis showed that the absence of lymph node and distant metastases, differentiation grade, and curative resection were associated with prolonged survival for all males, whereas tumor size, differentiation grade, and the presence of lymph node metastases influenced the overall or disease-free survival of patients after curative resection (all P < 0.05). On the other hand, Nevin stage was an independent marker for both overall survival for all females and overall and disease-free survival for female patients who underwent curative resection. Additionally, resection type and differentiation grade were of independent prognostic significance for different subgroups of females (all P < 0.05). Our data suggested that tumor-related factors affect prognosis of both male and female patients with GBC after resection. Of these factors, tumor differentiation status might be more significant for males, but Nevin stage had a stronger predictive potential for females.

Nuclear Hormone Receptors and Their Ligands: Metabolites in Control of Transcription.

Nuclear hormone receptors are a family of transcription factors regulated by small molecules derived from the endogenous metabolism or diet. There are forty-eight nuclear hormone receptors in the human genome, twenty of which are still orphans. In this review, we make a brief historical journey from the first observations by Berthold in 1849 to the era of orphan receptors that began with the sequencing of the Caenorhabditis elegans genome in 1998. We discuss the evolution of nuclear hormone receptors and the putative ancestral ligands as well as how the ligand universe has expanded over time. This leads us to define four classes of metabolites-fatty acids, terpenoids, porphyrins and amino acid derivatives-that generate all known ligands for nuclear hormone receptors. We conclude by discussing the ongoing efforts to identify new classes of ligands for orphan receptors.

Single-molecule real-time sequencing of the full-length transcriptome of loquat under low-temperature stress.

In this study, third-generation full-length (FL) transcriptome sequencing was performed of loquat using single-molecule real-time(SMRT) sequencing from the pooled cDNA of embryos of young loquat fruit under different low temperatures (three biological replicates for treatments of 1°C, -1°C, and -3°C, for 12 h or 24 h) and the control group(three biological replicates for treatments of room temperature), Illumina sequencing was used to correct FL transcriptome sequences. A total of 3 PacBio Iso-Seq libraries (1-2 kb, 2-3 kb and 3-6 kb) and 21 Illumina transcriptome libraries were constructed, a total of 13.41 Gb of clean reads were generated, which included 215,636 reads of insert (ROIs) and 121,654 FL, non-chimaric (FLNC) reads. Transcript clustering analysis of the FLNC reads revealed 76,586 consensus isoforms, and a total of 12,520 high-quality transcript sequences corrected with non-FL sequences were used for subsequent analysis. After the redundant reads were removed, 38,435 transcripts were obtained. A total of 27,905 coding DNA sequences (CDSs) were identified, and 407 long non-coding RNAs (lncRNAs) were ultimately predicted. Additionally, 24,832 simple sequence repeats (SSRs) were identified, and a total of 1,295 alternative splicing (AS) events were predicted. Furthermore, 37,993 transcripts were annotated in eight functional databases. This is the first study to perform SMRT sequencing of the FL transcriptome of loquat. The obtained transcriptomic data are conducive for further exploration of the mechanism of loquat freezing injury and thus serve as an important theoretical basis for generating new loquat material and for identifying new ways to improve loquat cold resistance.

Calcium diffusion enhanced after cleavage of negatively charged components of brain extracellular matrix by chondroitinase ABC.

The concentration of extracellular calcium plays a critical role in synaptic transmission and neuronal excitability as well as other physiological processes. The time course and extent of local fluctuations in the concentration of this ion largely depend on its effective diffusion coefficient (D*) and it has been speculated that fixed negative charges on chondroitin sulphate proteoglycans (CSPGs) and other components of the extracellular matrix may influence calcium diffusion because it is a divalent cation. In this study we used ion-selective microelectrodes combined with pressure ejection or iontophoresis of ions from a micropipette to quantify diffusion characteristics of neocortex and hippocampus in rat brain slices. We show that D* for calcium is less than the value predicted from the behaviour of the monovalent cation tetramethylammonium (TMA), a commonly used diffusion probe, but D* for calcium increases in both brain regions after the slices are treated with chondroitinase ABC, an enzyme that predominantly cleaves chondroitin sulphate glycans. These results suggest that CSPGs do play a role in determining the local diffusion properties of calcium in brain tissue, most likely through electrostatic interactions mediating rapid equilibrium binding. In contrast, chondroitinase ABC does not affect either the TMA diffusion or the extracellular volume fraction, indicating that the enzyme does not alter the structure of the extracellular space and that the diffusion of small monovalent cations is not affected by CSPGs in the normal brain ionic milieu. Both calcium and CSPGs are known to have many distinct roles in brain physiology, including brain repair, and our study suggests they may be functionally coupled through calcium diffusion properties.

Involvement of an alternatively spliced mitochondrial oxodicarboxylate carrier in adipogenesis in 3T3-L1 cells.

BACKGROUND: Adipogenesis is a complex process that involves many genes/proteins at different stages of differentiation. In order to identify genes critical for adipogenesis, we took a novel approach based on phenotype change of individual cell, to search for genes with regulatory roles in adipogenesis genome-wide in 3T3-L1 cells. METHODS: Lentivirus-based inducible random homologous knockdown was used for the screening of functional gene that altered lipid formation in the adipocyte during differentiation. RESULTS: In the present study, we reported the identification of an alternatively spliced mitochondrial oxodicarboxylate carrier (ODC), so named ODC-AS. ODC-AS is different from ODC by replacing 22 amino acids with 29 amino acids at the N-terminal. ODC was widely expressed in most tissues in mouse as determined by multi-tissue cDNA panel polymerase chain reaction. However, ODC-AS was only detected in adipose tissue and in iris and sclera-choroid complex of the eye. The expression of ODC-AS in 3T3-L1 was detected after the induction of differentiation, and reached a peak at day 4 and then reduced thereafter, whereas no ODC transcript detected in the cells neither before nor after differentiation. Knocking down of ODC-AS expression by RNA interference led to significant reduction in lipid accumulation as determined by triglyceride measurement and Nile Red staining, as well as adipogenic marker CEBPalpha, PPARgamma, aP2 and CD36. Although both ODC and ODC-AS are expressed in white and brown adipose tissues, only the expression of ODC-AS was down-regulated in brown adipose tissue by cold exposure. CONCLUSION: These results implicate that ODC-AS may promote lipid accumulation during adipocyte differentiation and play an important role in the regulation of lipid metabolism in adipose tissues.