Efficacy and safety of tibial nerve stimulation using a wearable device for overactive bladder.

OBJECTIVE: To evaluate the efficacy and safety of a wearable, smartphone-controlled, rechargeable transcutaneous tibial nerve stimulation (TTNS) device in patients with overactive bladder (OAB). PATIENTS AND METHODS: This multicentre, prospective, single-blind, randomised clinical trial included eligible patients with OAB symptoms who were randomly assigned to the stimulation group or sham group. The primary efficacy outcome was change from baseline in voiding frequency/24 h after 4 weeks of treatment. The secondary efficacy outcomes included changes in bladder diary outcomes (urgency score/void, nocturia episodes/day, micturition volume/void, and incontinence episodes/day), questionnaires on Overactive Bladder Symptom Score (OABSS), Patient Perception of Bladder Condition (PPBC), and American Urological Association Symptom Index Quality of Life Score (AUA-SI-QoL) at baseline and after 4 weeks of treatment. Device-related adverse events (AEs) were also evaluated. RESULTS: In the full analysis set (FAS), the mean (sd) change of voiding frequency/24 h in the stimulation group and sham group at 4 weeks were -3.5 (2.9) and -0.6 (2.4), respectively (P < 0.01). Similar results were obtained in the per-protocol set (PPS): -3.5 (2.9) vs -0.4 (2.3) (P < 0.01). In the FAS and PPS, micturition volume/void significantly improved at 4 weeks (P = 0.01 and P = 0.02). PPBC improvement almost reached significance in the FAS (P = 0.05), while it was significant in the PPS (P = 0.02). In the FAS and PPS, AUA-SI-QoL significantly improved at 4 weeks in the two groups (P < 0.01 and P < 0.01), whereas there were no significant differences in urgency score/void, nocturia episodes/day or OABSS between the groups. Also, no device-related serious AEs were reported. CONCLUSIONS: The non-invasive neuromodulation technique using the novel ambulatory TTNS device is effective and safe for treating OAB. Its convenience and easy maintenance make it a new potential home-based treatment modality. Future studies are warranted to confirm its longer-term efficacy.

Development and validation of a diagnostic nomogram for sarcopenia in Chinese hemodialysis patients.

BACKGROUND: Sarcopenia is a clinical condition that is common in patients with chronic kidney disease (CKD), especially in those on dialysis. However, the relatively complicated diagnostic procedure limits its use in clinical situations. In this study we aimed to establish a simplified tool for the diagnosis of sarcopenia in patients on hemodialysis (HD). METHODS: Overall, 757 eligible patients from seven HD centers in Shanghai and Suzhou, China, were recruited from 2020 to 2021. The cross-sectional data were analyzed. Sarcopenia was diagnosed according to the Asian Working Group for Sarcopenia 2019 criteria. Among them, 511 consecutive patients (77 with and 434 without sarcopenia) from five centers were included in the training set for the establishment of a diagnostic nomogram. Ten investigative parameters including clinical characteristics, body measurements and physical performance were used to derive the diagnostic nomogram. A total of 246 consecutive patients (47 with and 199 without sarcopenia) were included for validation of the diagnostic model. RESULTS: The average age of the enrolled patients was 60.4 ± 12.1 years, 59.8% were males and 90.5% received dialysis using an arteriovenous fistula. Overall, the sarcopenia rate was 16.4%. The training and validation sets showed no significant differences in sarcopenia rate (15.1% and 19.1%, respectively; P = .160). The nomogram derived from the training set for sarcopenia, which was based on only four features-age, sex, body weight and grip strength-achieved high C-indexes of 0.929 [95% confidence interval (CI) 0.904-0.953] and 0.955 (95% CI 0.931-0.979) in the training and external sets, respectively, and had a well-fitted calibration curve. The cut-off value was 0.725, with a sensitivity of 0.909 and a specificity of 0.816. The nomogram accurately diagnosed sarcopenia with fewer variables and more simplified diagnostic procedures. CONCLUSIONS: The nomogram had a good diagnostic capability for sarcopenia in patients on HD and may be a convenient tool for clinical use.

Automated regional citrate anticoagulation based on online monitoring of ionized calcium concentration: Proof of concept.

BACKGROUND: Regional citrate anticoagulation (RCA), a complex and effective technique, is recommended as the anticoagulation of choice for continuous renal replacement therapy. One of its key objectives is to keep the ionized calcium in the targeted range. In this study, we aimed to develop an automated RCA based on online monitoring of the ionized calcium concentration and closed-loop feedback. METHODS: We constructed calcium-selective electrodes with liquid inner contact, which measured a potentiometric signal as the output. We tested the responses, stability, and selectivity of the electrodes in flowing fluid containing calcium chloride. We compared the measurement accuracy between the electrodes and an i-STAT system in vivo. Moreover, we established closed-loop feedback using a proportional-integral-derivative controller model. We performed simulated automated RCA both in vivo and in vitro. RESULTS: The electrode gave a Nernstian response to the variation of ionized calcium concentration. It showed high stability and a relatively short response time. Changes in the fluid flow rate, solution PH, and addition of metal ions including Mg2+ and K+ did not interfere with the measurements of ionized calcium. These measurements in whole blood by the electrode were very close to those assessed by the i-STAT system. The feedback control system responded quickly to an abnormal ionized calcium concentration and regulated the infusion rates of calcium or citrate to maintain the concentration of ionized calcium within the targeted range. CONCLUSIONS: We successfully trialed automated RCA, which may help simplify the complexities of RCA in the future.

Circulating serum exosomal miR-92a-3p as a novel biomarker for early diagnosis of gastric cancer.

Gastric cancer (GC) is one of the common malignant tumors with high mortality. The abundance of miRNAs in serum exosomes has proved to have a high application value as a new noninvasive diagnostic method. The purpose of this study was to investigate whether serum exosomal miR-92a-3p could be used as a new biomarker for early diagnosis of GC and evaluate its clinical application value by detecting the expression of serum exosomal miR-92a-3p in 131 patients with primary GC and 122 healthy controls by real-time quantitative (qRT)-PCR. The results showed that the expression level of serum exosomal miR-92a-3p in GC patients was significantly lower than that in normal controls (p < 0.0001). In addition, the level was closely correlated with lymph node metastasis and tumor node metastasis stage of GC patients. The area under the curve for serum exosomal miR-92a-3p was 0.829, significantly higher than for other indicators. Furthermore, combined detection of serum exosomal miR-92a-3p, CEA and CA19-9 was more sensitive than any of the three alone or any pair. These results showed that serum exosomal miR-92a-3p could be used as a novel new tumor biomarker to improve diagnostic efficiency in GC.

Fucosyltransferase 2 induced epithelial-mesenchymal transition via TGF-ß/Smad signaling pathway in lung adenocarcinaoma.

Fucosyltransferase 2 (FUT2), the enzyme catalyzing α-1,2-fucosylation in mammals, has been implicated in cancer. The up-regulation of FUT2 has been observed in lung adenocarcinoma (LUAD), and FUT2 can enhance the cell migration and invasion of LUAD cell lines. However, the underlying mechanism of FUT2 in LUAD remains largely unknown. Abundant studies have revealed that epithelial-mesenchymal transition (EMT) played a pivotal role during lung cancer metastasis and progression. In the present study, we showed that knocking down FUT2 in LUAD cell lines increased the expression of E-cadherin and reduced the expression of Vimentin, N-cadherin, TßRII, p-Smad2, p-Smad3 and Snail, which were the makers of EMT. Meanwhile, the expression of E-cadherin was decreased, and the expression of Vimentin was increased by restoring the expression of FUT2 in RNA interference FUT2 (RNAi-FUT2) cells, suggesting that FUT2 enhanced the EMT process in LUAD. Additionally, silencing FUT2 expression can up-regulate E-cadherin and down-regulate Vimentin, significantly attenuated EMT in vivo. Treated with the SIS3, a new-type inhibitor of p-Smad3 of TGF-ß signaling, the expression of E-cadherin, Vimentin and Snail were not affected by RNAi-FUT2 cells, indicating that the effect of FUT2 on EMT depended on TGF-ß/Smad signaling. Overall, the current results indicated that FUT2 might promote LUAD metastasis through the EMT initiated by TGF-ß/Smad signaling. Therefore, FUT2 might be a prognostic factor and therapeutic target for LUAD.

Bisphenol A analogs in patients with chronic kidney disease and dialysis therapy.

Bisphenol A (BPA) accumulates in patients with chronic kidney disease (CKD), and hemodialysis filters may contribute to bisphenol burden in patients on hemodialysis (HD). The serum levels of BPA and three BPA analogs, namely, bisphenol B (BPB), bisphenol S (BPS), and bisphenol F (BPF), in 58 patients with CKD, 66 patients on dialysis therapy and 30 healthy control were investigated. The content of four bisphenols (BPs) was also examined in three types of dialysis filters, followed by an in vitro elution experiment to test the release of BPs from the dialysis filters. The serum levels of BPA (r = -0.746, p < 0.05) and BPS (r = -0.433, p < 0.05) in 58 CKD patients and 30 healthy control were correlated with the decrease in estimated glomerular filtration rate. The serum levels of BPs in the HD patients were higher than those in the peritoneal dialysis patients (p < 0.05). In the in vitro study on the BP contents in dialysis filters, BPA was the main form of the BPs in the polysulfone membrane (20.86 ±â€¯1.18 ng/mg) and in the polyamide membrane (18.70 ±â€¯2.88 ng/mg), and a modicum of BPS (0.01 ±â€¯0.01 ng/mg) was detected in the polyethersulfone membrane. The results of the elution experiment were in accordance with the results of BPs content in the dialysis filters. Insufficient renal function may lead to BPs accumulation in patients with CKD, and BPs in dialysis products may cause BPs burden in patients on HD.

Assessment of triglyceride and cholesterol in overweight people based on multiple linear regression and artificial intelligence model.

BACKGROUND: The prevalence of high hyperlipemia is increasing around the world. Our aims are to analyze the relationship of triglyceride (TG) and cholesterol (TC) with indexes of liver function and kidney function, and to develop a prediction model of TG, TC in overweight people. METHODS: A total of 302 adult healthy subjects and 273 overweight subjects were enrolled in this study. The levels of fasting indexes of TG (fs-TG), TC (fs-TC), blood glucose, liver function, and kidney function were measured and analyzed by correlation analysis and multiple linear regression (MRL). The back propagation artificial neural network (BP-ANN) was applied to develop prediction models of fs-TG and fs-TC. RESULTS: The results showed there was significant difference in biochemical indexes between healthy people and overweight people. The correlation analysis showed fs-TG was related to weight, height, blood glucose, and indexes of liver and kidney function; while fs-TC was correlated with age, indexes of liver function (P < 0.01). The MRL analysis indicated regression equations of fs-TG and fs-TC both had statistic significant (P < 0.01) when included independent indexes. The BP-ANN model of fs-TG reached training goal at 59 epoch, while fs-TC model achieved high prediction accuracy after training 1000 epoch. CONCLUSIONS: In conclusions, there was high relationship of fs-TG and fs-TC with weight, height, age, blood glucose, indexes of liver function and kidney function. Based on related variables, the indexes of fs-TG and fs-TC can be predicted by BP-ANN models in overweight people.

The predictive value of the product of contrast medium volume and urinary albumin/creatinine ratio in contrast-induced acute kidney injury.

Preexisting renal impairment and the amount of contrast media are the most important risk factors for contrast-induced acute kidney injury (CI-AKI). We aimed to investigate whether the product of contrast medium volume and urinary albumin/creatinine ratio (CMV × UACR) would be a better predictor of CI-AKI in patients undergoing nonemergency coronary interventions. This was a prospective single-center observational study, and 912 consecutive patients who were exposed to contrast media during coronary interventions were investigated prospectively. CI-AKI is defined as a 44.2 µmol/L rise in serum creatinine or a 25% increase, assessed within 48 h after administration of contrast media in the absence of other causes. Fifty patients (5.48%) developed CI-AKI. The urinary albumin/creatinine ratio (UACR) (OR = 1.002, 95% CI = 1.000-1.003, p = .012) and contrast medium volume (CMV) (OR = 1.008, 95% CI = 1.001-1.014, p = .017) were independent risk factors for the development of CI-AKI. The area under the ROC curve of CMV, UACR and CMV × UACR were 0.662 (95% CI = 0.584-0.741, p < .001), 0.761 (95% CI = 0.674-0.847, p < .001) and 0.808 (95% CI = 0.747-0.896, p < .001), respectively. The cutoff value of CMV × UACR to predict CI-AKI was 1186.2, with 80.0% sensitivity and 62.2% specificity. The product of CMV and UACR (CMV × UACR) might be a predictor of CI-AKI in patients undergoing nonemergency coronary interventions, which was superior to CMV or UACR alone.

Deletion of the Proposed Iron Chaperones IscA/SufA Results in Accumulation of a Red Intermediate Cysteine Desulfurase IscS in Escherichia coli.

In Escherichia coli, sulfur in iron-sulfur clusters is primarily derived from L-cysteine via the cysteine desulfurase IscS. However, the iron donor for iron-sulfur cluster assembly remains elusive. Previous studies have shown that, among the iron-sulfur cluster assembly proteins in E. coli, IscA has a unique and strong iron-binding activity and that the iron-bound IscA can efficiently provide iron for iron-sulfur cluster assembly in proteins in vitro, indicating that IscA may act as an iron chaperone for iron-sulfur cluster biogenesis. Here we report that deletion of IscA and its paralog SufA in E. coli cells results in the accumulation of a red-colored cysteine desulfurase IscS under aerobic growth conditions. Depletion of intracellular iron using a membrane-permeable iron chelator, 2,2'-dipyridyl, also leads to the accumulation of red IscS in wild-type E. coli cells, suggesting that the deletion of IscA/SufA may be emulated by depletion of intracellular iron. Purified red IscS has an absorption peak at 528 nm in addition to the peak at 395 nm of pyridoxal 5'-phosphate. When red IscS is oxidized by hydrogen peroxide, the peak at 528 nm is shifted to 510 nm, which is similar to that of alanine-quinonoid intermediate in cysteine desulfurases. Indeed, red IscS can also be produced in vitro by incubating wild-type IscS with excess L-alanine and sulfide. The results led us to propose that deletion of IscA/SufA may disrupt the iron delivery for iron-sulfur cluster biogenesis, therefore impeding sulfur delivery by IscS, and result in the accumulation of red IscS in E. coli cells.

Identification of the differential expression of serum microRNA in type 2 diabetes.

The identification of disease-specific alterations in miRNA expression and the ability to detect miRNAs in serum furnish the basis for identified potential research value. This study was aimed to characterize the expression of miRNAs in the serum samples from people with type 2 diabetes mellitus (T2DM) and healthy individuals in order to detect the differential expression of miRNAs in T2DM. In total, 582 participants were recruited. Microarray-based miRNA expression profiles were screened in pooled serum samples from two groups (T2DM and healthy control). The candidates' miRNAs were validated by reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR). Five significantly different serum miRNAs were identified in T2DM patients (hsa-miR-320d, hsa-miR-4534, hsa-miR-3960, hsa-miR-451a, and hsa-miR-572) compared to those in the serum of healthy controls. This study provided evidence that serum miRNAs had differential expressions between healthy controls and T2DM patients. These five differential expression miRNAs might be of help for subsequent study in T2DM.

Prenatal Diagnosis of DNA Copy Number Variations by Genomic Single-Nucleotide Polymorphism Array in Fetuses with Congenital Heart Defects.

OBJECTIVES: To evaluate the usefulness of single-nucleotide polymorphism (SNP) array for prenatal genetic diagnosis of congenital heart defect (CHD), we used this approach to detect clinically significant copy number variants (CNVs) in fetuses with CHDs. METHODS: A HumanCytoSNP-12 array was used to detect genomic samples obtained from 39 fetuses that exhibited cardiovascular abnormalities on ultrasound and had a normal karyotype. The relationship between CNVs and CHDs was identified by using genotype-phenotype comparisons and searching of chromosomal databases. All clinically significant CNVs were confirmed by real-time PCR. RESULTS: CNVs were detected in 38/39 (97.4%) fetuses: variants of unknown significance were detected in 2/39 (5.1%), and clinically significant CNVs were identified in 7/39 (17.9%). In 3 of the 7 fetuses with clinically significant CNVs, 3 rare and previously undescribed CNVs were detected, and these CNVs encompassed the CHD candidate genes FLNA (Xq28 dup), BCOR (Xp11.4 dup), and RBL2 (16q12.2 del). CONCLUSION: Compared with conventional cytogenetic genomics, SNP array analysis provides significantly improved detection of submicroscopic genomic aberrations in pregnancies with CHDs. Based on these results, we propose that genomic SNP array is an effective method which could be used in the prenatal diagnostic test to assist genetic counseling for pregnancies with CHDs.

Copper binding in IscA inhibits iron-sulphur cluster assembly in Escherichia coli.

Among the iron-sulphur cluster assembly proteins encoded by gene cluster iscSUA-hscBA-fdx in Escherichia coli, IscA has a unique and strong iron binding activity and can provide iron for iron-sulphur cluster assembly in proteins in vitro. Deletion of IscA and its paralogue SufA results in an E. coli mutant that fails to assemble [4Fe-4S] clusters in proteins under aerobic conditions, suggesting that IscA has a crucial role for iron-sulphur cluster biogenesis. Here we report that among the iron-sulphur cluster assembly proteins, IscA also has a strong and specific binding activity for Cu(I) in vivo and in vitro. The Cu(I) centre in IscA is stable and resistant to oxidation under aerobic conditions. Mutation of the conserved cysteine residues that are essential for the iron binding in IscA abolishes the copper binding activity, indicating that copper and iron may share the same binding site in the protein. Additional studies reveal that copper can compete with iron for the metal binding site in IscA and effectively inhibits the IscA-mediated [4Fe-4S] cluster assembly in E. coli cells. The results suggest that copper may not only attack the [4Fe-4S] clusters in dehydratases, but also block the [4Fe-4S] cluster assembly in proteins by targeting IscA in cells.

The tRNA(Gly) T10003C mutation in mitochondrial haplogroup M11b in a Chinese family with diabetes decreases the steady-state level of tRNA(Gly), increases aberrant reactive oxygen species production, and reduces mitochondrial membrane potential.

Mitochondrial diabetes originates mainly from mutations located in maternally transmitted, mitochondrial tRNA-coding genes. In a genetic screening program of type 2 diabetes conducted with a Chinese Han population, we found one family with suggestive maternally transmitted diabetes. The proband's mitochondrial genome was analyzed using DNA sequencing. Total 42 known nucleoside changes and 1 novel variant were identified, and the entire mitochondrial DNA sequence was assigned to haplogroup M11b. Phylogenetic analysis showed that a homoplasmic mutation, 10003T>C transition, occurred at the highly conserved site in the gene encoding tRNA(Gly). Using a transmitochondrial cybrid cell line harboring this mutation, we observed that the steady-state level of tRNA(Gly) significantly affected and the amount of tRNA(Gly) decreased by 97%, production of reactive oxygen species was enhanced, and mitochondrial membrane potential, mtDNA copy number and cellular oxygen consumption rate were remarkably decreased compared with wild-type cybrid cells. The homoplasmic 10003T>C mutation in the mitochondrial tRNA(Gly) gene suggested to be as a pathogenesis-related mutation which might contribute to the maternal inherited diabetes in the Han Chinese family.

Reduced Glutathione for Prevention of Renal Outcomes in Patients Undergoing Selective Coronary Angiography or Intervention.

OBJECTIVES: To evaluate the effect of reduced glutathione on renal outcomes following the selective coronary angiography and/or intervention. BACKGROUND: Contrast agents can cause an acute reduction in renal function that may be due to the generation of reactive oxygen species. The role of antioxidants in prevention of this renal impairment is controversial. METHODS AND RESULTS: We conducted a randomized, placebo-controlled trial of reduced glutathione in 825 patients who underwent selective coronary angiography and/or intervention. Patients were assigned to reduced glutathione 1800 mg (n = 416) or placebo (n = 411) intravenously. Contrast-induced acute kidney injury was defined by an absolute increase of serum creatinine ≥0.5 mg/dl (44.2 µmol/L) or a relative increase of ≥25% measured 48 hours after the procedure. The incidence of contrast-induced acute kidney injury was 5.07% in the glutathione group and 4.97% in the control group (relative risk, 1.04; 95% confidence interval, 0.59-1.83; P = 0.886). Change in serum malondialdehyde was (-) 1.01 ± 1.69 nmol/ml in the glutathione group and (-) 0.67 ± 1.55 nmol/ml in the control group (P = 0.054), and change in serum total antioxidant capacity level was also similar in both groups (0.91 ± 2.06 nmol/ml and 0.79 ± 2.18 nmol/ml, respectively; P = 0.936). CONCLUSIONS: A single dose of reduced glutathione does not reduce the risk of contrast-induced acute kidney injury in patients undergoing coronary angiography and/or intervention.

Programmable engineering of a biosensing interface with tetrahedral DNA nanostructures for ultrasensitive DNA detection.

Self-assembled DNA nanostructures with precise sizes allow a programmable "soft lithography" approach to engineer the interface of electrochemical DNA sensors. By using millimeter-sized gold electrodes modified with several types of tetrahedral DNA nanostructures (TDNs) of different sizes, both the kinetics and thermodynamics of DNA hybridization were profoundly affected. Because each DNA probe is anchored on an individual TDN, its lateral spacing and interactions are finely tuned by the TDN size. By simply varying the size of the TDNs, the hybridization time was decreased and the hybridization efficiency was increased. More significantly, the detection limit for DNA detection was tuned over four orders of magnitude with differentially nanostructured electrodes, and achieved attomolar sensitivity with polymeric enzyme amplification.

Ultrasensitive electrochemical detection of prostate-specific antigen by using antibodies anchored on a DNA nanostructural scaffold.

The high occurrence of prostate cancer in men makes the prostate-specific antigen (PSA) screening test really important. More importantly, the recurrence rate after radical prostatectomy is high, whereas the traditional PSA immunoassay does not possess the sufficient high sensitivity for post-treatment PSA detection. In these assays, uncontrolled and random orientation of capture antibodies on the surface largely reduces their activity. Here, by exploiting the rapidly emerging DNA nanotechnology, we developed a DNA nanostructure based scaffold to precisely control the assembly of antibody monolayer. We demonstrated that the detection sensitivity was critically dependent on the nanoscale-spacing (nanospacing) of immobilized antibodies. In addition to the controlled assembly, we further amplified the sensing signal by using the gold nanoparticles, resulting in extremely high sensitivity and a low detection limit of 1 pg/mL. To test the real-world applicability of our nanoengineered electrochemical sensor, we evaluated the performance with 11 patients' serum samples and obtained consistent results with the "gold-standard" assays.

Brief Report: Single-nucleotide polymorphisms in VKORC1 are risk factors for systemic lupus erythematosus in Asians.

OBJECTIVE: The increased risk of thrombosis in systemic lupus erythematosus (SLE) may be partially explained by interrelated genetic pathways for thrombosis and SLE. The present study was undertaken to investigate whether 33 established and novel single-nucleotide polymorphisms (SNPs) in 20 genes involved in hemostasis pathways that have been associated with deep venous thrombosis (DVT) in the general population are risk factors for SLE among Asian subjects. METHODS: Patients in the discovery cohort were enrolled in 1 of 2 North American SLE cohorts. Patients in the replication cohort were enrolled in 1 of 4 Asian or 2 North American cohorts. We first genotyped 263 Asian patients with SLE and 357 healthy Asian control subjects for 33 SNPs in the discovery phase, and then genotyped 5 SNPs in up to an additional 1,496 patients and 993 controls in the replication phase. Patients were compared to controls for bivariate association with minor alleles. Principal components analysis was used to control for intra-Asian ancestry in the replication cohort. RESULTS: Two genetic variants in the gene VKORC1 were highly significant in both the discovery and replication cohorts: rs9934438 (in the discovery cohort, odds ratio [OR] 2.45, P=2×10(-9); in the replication cohort, OR 1.54, P=4×10(-6)) and rs9923231 (in the discovery cohort, OR 2.40, P=6×10(-9); in the replication cohort, OR 1.53, P=5×10(-6)). These associations were significant in the replication cohort after adjustment for intra-Asian ancestry: for rs9934438, OR 1.34, P=0.0029; for rs9923231, OR 1.34, P=0.0032. CONCLUSION: Genetic variants in VKORC1, which are involved in vitamin K reduction and associated with DVT, correlate with SLE development in Asian subjects. These results suggest that there may be intersecting genetic pathways for the development of SLE and thrombosis.

Differential requirement of RasGRP1 for γδ T cell development and activation.

γδ T (γδT) cells belong to a distinct T cell lineage that performs immune functions different from αß T (αßT) cells. Previous studies established that Erk1/2 MAPKs are critical for positive selection of αßT cells. Additional evidence suggests that increased Erk1/2 activity promotes γδT cell generation. RasGRP1, a guanine nucleotide-releasing factor for Ras, plays an important role in positive selection of αßT cells by activating the Ras-Erk1/2 pathway. In this article, we demonstrate that RasGRP1 is critical for TCR-induced Erk1/2 activation in γδT cells, but it exerts different roles for γδT cell generation and activation. Deficiency of RasGRP1 does not obviously affect γδT cell numbers in the thymus, but it leads to increased γδT cells, particularly CD4(-)CD8(+) γδT cells, in the peripheral lymphoid organs. The virtually unhindered γδT cell development in the RasGRP1(-/-) thymus proved to be cell intrinsic, whereas the increase in CD8(+) γδT cells is caused by non-cell-intrinsic mechanisms. Our data provide genetic evidence that decreased Erk1/2 activation in the absence of RasGRP1 is compatible with γδT cell generation. Although RasGRP1 is dispensable for γδT cell generation, RasGRP1-deficient γδT cells are defective in proliferation following TCR stimulation. Additionally, RasGRP1-deficient γδT cells are impaired to produce IL-17 but not IFNγ. Together, these observations revealed that RasGRP1 plays differential roles for γδ and αß T cell development but is critical for γδT cell proliferation and production of IL-17.

Iron and zinc binding activity of Escherichia coli topoisomerase I homolog YrdD.

YrdD, a homolog of the C-terminal zinc-binding region of Escherichia coli topoisomerase I, is highly conserved among proteobacteria and enterobacteria. However, the function of YrdD remains elusive. Here we report that YrdD purified from E. coli cells grown in LB media contains both zinc and iron. Supplement of exogenous zinc in the medium abolishes the iron binding of YrdD in E. coli cells, indicating that iron and zinc may compete for the same metal binding sites in the protein. While the zinc-bound YrdD is able to bind single-stranded (ss) DNA and protect ssDNA from the DNase I digestion in vitro, the iron-bound YrdD has very little or no binding activity for ssDNA, suggesting that the zinc-bound YrdD may have an important role in DNA repair by interacting with ssDNA in cells.

Exposure to high glutamate concentration activates aerobic glycolysis but inhibits ATP-linked respiration in cultured cortical astrocytes.

Astrocytes play a key role in removing the synaptically released glutamate from the extracellular space and maintaining the glutamate below neurotoxic level in the brain. However, high concentration of glutamate leads to toxicity in astrocytes, and the underlying mechanisms are unclear. The purpose of this study was to investigate whether energy metabolism disorder, especially impairment of mitochondrial respiration, is involved in the glutamate-induced gliotoxicity. Exposure to 10-mM glutamate for 48 h stimulated glycolysis and respiration in astrocytes. However, the increased oxygen consumption was used for proton leak and non-mitochondrial respiration, but not for oxidative phosphorylation and ATP generation. When the exposure time extended to 72 h, glycolysis was still activated for ATP generation, but the mitochondrial ATP-linked respiration of astrocytes was reduced. The glutamate-induced astrocyte damage can be mimicked by the non-metabolized substrate d-aspartate but reversed by the non-selective glutamate transporter inhibitor TBOA. In addition, the glutamate toxicity can be partially reversed by vitamin E. These findings demonstrate that changes of bioenergetic profile occur in cultured cortical astrocytes exposed to high concentration of glutamate and highlight the role of mitochondria respiration in glutamate-induced gliotoxicity in cortical astrocytes.