Research on investment optimization and coordination of fresh supply chain considering misreporting behavior under blockchain technology.

In the traditional fresh supply chain, farmers commonly conceal the true quality information of their products in order to achieve better sales. This article focuses on the use of blockchain technology to address the issue of false freshness reporting in a two-level fresh supply chain consisting of a rural cooperative and a supermarket. Taking into account the dual losses of quality and quantity in the process of agricultural products transportation, the impacts of the product freshness and the blockchain investment level on random market demand are quantified in this paper. And game models for centralized and decentralized decision-making before and after investing in blockchain technology are proposed. By comparing the supply chain optimal decisions and performances under different scenarios, a revenue-cost sharing contract is designed to coordinate the decentralized decision-making. Simulation results show that the application of the blockchain technology can further consolidate the superiority of the centralized decision-making. However, there is a certain threshold for the application of the blockchain technology in decentralized decision-making. When the unit cost of blockchain exceeds the threshold, the rural cooperative will abandon its cooperation with the supermarket due to reduced profits. And the combined contract also has a threshold boundary for its coordinating effect on decentralized decision-making.

penA profile of Neisseria gonorrhoeae in Guangdong, China: Novel penA alleles are related to decreased susceptibility to ceftriaxone or cefixime.

BACKGROUND: Resistance to extended-spectrum cephalosporins (ESCs) has become a public health concern with the spread of Neisseria gonorrhoeae and increasing antimicrobial resistance. Mutation of penA, encoding penicillin-binding protein 2, represents a mechanism of ESC resistance. This study sought to assess penA alleles and mutations associated with decreased susceptibility (DS) to ESCs in N. gonorrhoeae. MATERIALS AND METHODS: In 2021, 347 gonococci were collected in Guangdong, China. Minimum inhibitory concentations (MICs) of ceftriaxone and cefixime were determined, and whole-genome sequencing and phylogenetic analysis were performed. Multi-locus sequence typing (MLST) and conventional resistance determinants such as penA, mtrR, PonA and PorB were analysed. penA was genotyped and sequence-aligned using PubMLST. RESULTS: Genome-wide phylogenetic analysis revealed that the prevalence of DS to ESCs was highest in Clade 11.1 (100.0%), Clade 2 (66.7%) and Clade 0 (55.7%), and the leading cause was strains with penA-60.001 or new penA alleles in clades. The penA phylogenetic tree is divided into two branches: non-mosaic penA and mosaic penA. The latter contained penA-60.001, penA-10 and penA-34. penA profile analysis indicated that A311V and T483S are closely related to DS to ESCs in mosaic penA. The new alleles NEIS1753_2840 and NEIS1753_2837 are closely related to penA-60.001, with DS to ceftriaxone and cefixime of 100%. NEIS1753_2660, a derivative of penA-10 (A486V), has increased DS to ceftriaxone. NEIS1753_2846, a derivative of penA-34.007 (G546S), has increased DS to cefixime. CONCLUSION: This study identified critical penA alleles related to elevated MICs, and trends of gonococcus-evolved mutated penA associated with DS to ESCs in Guangdong.

An isothermal CRISPR-based diagnostic assay for Neisseria gonorrhoeae and Chlamydia trachomatis detection.

IMPORTANCE: A method for Neisseria gonorrhoeae (NG)/Chlamydia trachomatis (CT) detection is developed using multiplex-recombinase polymerase amplification and Cas12a/Cas13a. This method can detect NG and CT simultaneously with high sensitivity and specificity. This method has great potential to be further developed into larger-scale screening and point-of-care testing (POCT).

PCP4 Promotes Alzheimer's Disease Pathogenesis by Affecting Amyloid-ß Protein Precursor Processing.

BACKGROUND: Down syndrome (DS) is caused by an extra copy of all or part of chromosome 21. The patients with DS develop typical Alzheimer's disease (AD) neuropathology, indicating the role of genes on human chromosome 21 (HSA21) in the pathogenesis of AD. Purkinje cell protein 4 (PCP4), also known as brain-specific protein 19, is a critical gene located on HSA21. However, the role of PCP4 in DS and AD pathogenesis is not clear. OBJECTIVE: To explore the role of PCP4 in amyloid-ß protein precursor (AßPP) processing in AD. METHODS: In this study, we investigated the role of PCP4 in AD progression in vitro and in vivo. In vitro experiments, we overexpressed PCP4 in human Swedish mutant AßPP stable expression or neural cell lines. In vitro experiments, APP23/PS45 double transgenic mice were selected and treated with AAV-PCP4. Multiple topics were detected by western blot, RT-PCR, immunohistochemical and behavioral test. RESULTS: We found that PCP4 expression was altered in AD. PCP4 was overexpressed in APP23/PS45 transgenic mice and PCP4 affected the processing of AßPP. The production of amyloid-ß protein (Aß) was also promoted by PCP4. The upregulation of endogenous AßPP expression and the downregulation of ADAM10 were due to the transcriptional regulation of PCP4. In addition, PCP4 increased Aß deposition and neural plaque formation in the brain, and exuberated learning and memory impairment in transgenic AD model mice. CONCLUSION: Our finding reveals that PCP4 contributes to the pathogenesis of AD by affecting AßPP processing and suggests PCP4 as a novel therapeutic target for AD by targeting Aß pathology.

Dissemination of Neisseria gonorrhoeae with decreased susceptibility to extended-spectrum cephalosporins in Southern China, 2021: a genome-wide surveillance from 20 cities.

BACKGROUND: Antimicrobial resistance (AMR) of untreatable gonococcal infection is an emerging threat, especially in Guangdong, a prosperous province in Southern China. METHODS: N.gonorrhoeae was isolated from 20 cities in Guangdong and determined antimicrobial susceptibility. Through whole-genome sequencing (WGS), multilocus sequence typing (MLST), N.gonorrhoeae multiantigen sequence typing (NG-MAST), and N.gonorrhoeae sequence typing for antimicrobial resistance (NG-STAR) were obtained based on the PubMLST database ( https://pubmlst.org/ ). Phylogenetic analysis was used for dissemination and tracking analysis. RESULTS: Antimicrobial susceptibility was performed on 347 isolates, and 50 isolates were identified as decreased susceptibility (DS) to cephalosporins. Of which 16.0% (8/50) were ceftriaxone DS, 38.0% (19/50) were cefixime DS, and 46.0% (23/50) were both ceftriaxone and cefixime DS. In all, the dual-resistant rate of the cephalosporin-DS isolates was 96.0% for penicillin and 98.0% for tetracycline-resistant, and 10.0% (5/50) were resistant to azithromycin. All cephalosporin-DS isolates were resistant to ciprofloxacin but sensitive to spectinomycin. The predominant MLSTs were ST7363 (16%, 8/50), ST1903 (14%, 7/50), ST1901 (12%, 6/50), and ST7365 (10%, 5/50). Besides some isolates that failed genotyping (NA), NG-STAR ST1143 (n = 6) and NG-MAST ST17748 (n = 4) were the most prevalent. Twelve isolates with mosaic penA-60.001 allele retained the most elevated cephalosporin MIC (Minimum Inhibitory Concentration). Phylogenetic analysis revealed that epidemic penA-60.001 clones, either domestic or foreign, had spread to nine cities in Guangdong, and 9/12 clones were from the Pearl River Delta region. CONCLUSIONS: N. gonorrhoeae with cephalosporins-DS was extensively disseminated in Guangdong, Southern China, requiring strict surveillance.

Spatiotemporal trends of cardiovascular disease burden attributable to ambient PM2.5 from 1990 to 2019: A global burden of disease study.

There is little known about the global burden of CVD attributable to ambient PM2.5 (referred to as CVD burden hereinafter) and its secular trend across different regions and countries. We aimed to evaluate the spatiotemporal trends in CVD burden at the global, regional and national levels from 1990 to 2019. Data on CVD burden including mortality and disability adjusted of life years (DALYs) from 1990 to 2019 were extracted from the Global Burden of Disease Study 2019. Cases, the age-standardized rate of mortality (ASMR) and DALYs (ASDR) were estimated by age, sex and sociodemographic index (SDI). Estimated annual percentage change (EAPC) was calculated to evaluate the temporal changing in ASDR and ASMR from 1990 to 2019. In 2019, 2.48 million deaths and 60.91 million DALYs of CVD were attributed to ambient PM2.5 globally. Most CVD burden occurred in males, elderly and the middle SDI region. At national level, Uzbekistan, Egypt, and Iraq had the highest ASMR and ASDR. Despite remarkable increase in number of DALYs and deaths of CVD worldwide from 1990 to 2019, we observed nonsignificant change in ASMR (EAPC: 0.06, 95 % CI: -0.01, 0.13) and slight increment in ASDR (EAPC: 0.30, 95 % CI: 0.23, 0.37). The EAPCs of ASMR and ASDR were negatively associated with SDI in 2019, while the low-middle SDI region exhibited the fastest growth of ASMR and ASDR with EAPCs of 3.25 (95 % CI: 3.14, 3.37) and 3.36 (95 % CI: 3.22, 3.49), respectively. In conclusion, the global CVD burden attributable to ambient PM2.5 has largely increased over the past three decades. The population growth, aging and SDI contributed to the heterogeneity of spatial and temporal distribution. Enforcing policy to improving air quality is required to halt the growing burden of PM2.5 on health.

The Critical Role of microRNA-21 in Non-alcoholic Fatty Liver Disease Pathogenesis.

Nonalcoholic fatty liver disease (NAFLD) has received worldwide scientific attention because of its rapidly increasing prevalence, and it has emerged as a serious public health problem in end-stage liver disease. Many factors are involved in the multifactorial development and progression of liver disease by influencing multiple signaling and metabolic pathways. Currently, many studies have demonstrated the critical role of microRNA- 21 (miR-21) in NAFLD pathogenesis. In addition, many studies have found that miR-21 is highly expressed in inflammatory bowel disease, which is associated with intestinal barrier dysfunction and altered gut microbiota. In this paper, we focus on the regulatory role of miR-21 in the progression of NAFLD and its effect on the gut microbiota, summarize the involvement of miR-21 through a variety of signaling pathways and metabolic pathways, as well as discuss some predicted miR-21 target genes and miR-21 pathways for future experimental identification.

Association Between Serum Aldehydes and Hypertension in Adults: A Cross-Sectional Analysis of the National Health and Nutrition Examination Survey.

Background: Exposure to ambient pollutants and chemicals were found to be associated with increased risk of hypertension. However, the relationship between the increased aldehyde exposure and hypertension are still unclear. This study aimed to investigate the potential associations of serum aldehydes levels with prevalent hypertension. Methods: A total of 1,733 U.S. adults with data on hypertension outcome and serum aldehydes measurement from the National Health and Nutrition Examination Survey 2013-2014 were included. The serum levels of aldehydes were measured via an automated analytical method using solid phase microextraction gas chromatography and high-resolution mass spectrometry. Multivariate logistic regression models were adopted to assess the associations between six selected aldehydes exposure (benzaldehyde, butyraldehyde, heptanaldehyde, hexanaldehyde, isopentanaldehyde, and propanaldehyde) and prevalence of hypertension. Results: The mean age was 48.0 ± 16.7 years and an approximately equivalent of sex distribution was observed (female 49.9%). There seems to be a numerically higher level of hexanaldehyde in participants with hypertension when compared to participants without hypertension (2.6 ± 3.9 ng/mL vs. 2.3 ± 1.1 ng/mL). After adjusting for potential confounders, the odds ratio (OR) for hypertension was 2.15 [95% confidence interval (CI): 1.33-3.51] in participants from the highest quartile of serum hexanaldehyde concentration in comparison to those from the lowest quartile. Subgroup analyses and sensitivity analyses showed generally similar results. Conclusion: In summary, current evidence suggested that increased serum hexanaldehyde level was positively associated with prevalent hypertension in U.S. adults.

Chronic Alcohol Exposure Alters Gene Expression and Neurodegeneration Pathways in the Brain of Adult Mice.

BACKGROUND: Chronic alcohol consumption can alter the structure of the central nervous system and disrupt cognitive function. Alcoholics are more likely to develop neurodegenerative disorders such as Alzheimer's disease (AD) and Parkinson's disease (PD). However, the role of alcohol in promoting neurotoxicity and neurodegeneration remains unclear. OBJECTIVE: In this study, we aimed at estimating the effects of chronic binge alcohol exposure on brain transcriptome and behavior changes in a chronic "Drinking in the Dark" (DID) mouse model. METHODS: The adult C57BL/6J male mice were exposed to alcohol for 4 weeks. RNA-seq was applied to assess the effects of chronic alcohol exposure on transcriptome in brain. The open field test and novel object recognition test were used to assess the changes of anxiety level, locomotive function, and short-term memory induced by alcohol. RNA-seq analysis revealed that chronic alcohol exposure caused significant change in the brain transcriptome, especially in prefrontal cortex. RESULTS: The gene dysregulation caused by chronic alcohol exposure includes pathways related to mitochondrial energy metabolism (such as oxidative phosphorylation) and multiple neurodegenerative diseases (such as AD and PD). Furthermore, the pathway and network analyses suggest that the genes involved in mitochondrial energy metabolism, ubiquitin-proteasome system, Wnt signaling pathway, and microtubules may attribute to the neurotoxicity and neurodegeneration caused by chronic alcohol consumption. Additionally, locomotive function was also significantly impaired. CONCLUSION: This work provides gene transcriptional profile data for future research on alcohol-induced neurodegenerative diseases, especially AD and PD.

[Molecular chaperones facilitate soluble expression of recombinant non-toxic mutant CRM197 of diphtheria toxin in Escherichia coli].

Diphtheria toxin is an ADP-ribosyltransferase toxic to human cells. Mutation of the active site in its catalytic domain eliminates the toxicity, but retains its immunogenicity. A non-toxic mutant of diphtheria toxin known as CRM197 protein has become an ideal carrier protein for conjugate vaccines. CRM197 can further improve its immunogenicity by cross-linking with other antigens, so it has good potential to find broad applications. Unfortunately, inclusion bodies are easily formed during the expression of recombinant CRM197 protein in Escherichia coli, which greatly reduces its yield. In order to address this problem, pG-KJE8 vector carrying molecular chaperones and plasmid pET28a-CRM197, were co-expressed in Escherichia coli. The results showed that the recombinant CRM197 protein was successfully expressed and appeared largely in inclusion bodies. The molecular chaperones DnaK, DnaJ, GrpE, GroES and GroEL5 expressed can facilitate correct and rapid folding of CRM197. Furthermore, it can also improve the recovery rate of soluble CRM197 protein. The soluble expression of CRM197 was maximized upon addition of 1.0 mmol/L IPTG, 0.5 mg L-arabinose, 5.0 ng/mL tetracycline and induction at 20oC for 16 h. The soluble CRM197 protein shows good immunoreactivity, demonstrating the molecular chaperones expressed from pG-KJE8 facilitated the soluble expression of CRM197 protein in E. coli.

Inhibition of cystathionine ß-synthase promotes apoptosis and reduces cell proliferation in chronic myeloid leukemia.

Increased endogenous hydrogen sulfide (H2S) level by cystathionine ß-synthase (CBS) has been shown to closely relate tumorigenesis. H2S promotes angiogenesis, stimulates bioenergy metabolism and inhibits selective phosphatases. However, the role of CBS and H2S in chronic myeloid leukemia (CML) remains elusive. In this study, we found that CBS and H2S levels were increased in the bone marrow mononuclear cells of pediatric CML patients, as well as in the CML-derived K562 cells and CBS expression levels were correlated with different disease phases. Inhibition of CBS reduced the proliferation of the CML primary bone marrow mononuclear cells and induced growth inhibition, apoptosis, cell cycle arrest, and migration suppression in K562 cells and tumor xenografts. The knockdown of CBS expression by shRNA and inhibiting CBS activity by AOAA decreased the endogenous H2S levels, promoted mitochondrial-related apoptosis and inhibited the NF-κB-mediated gene expression. Our study suggests that inhibition of CBS induces cell apoptosis, as well as limits cell proliferation and migration, a potential target for the treatment of chronic myeloid leukemia.

A Case of Hemophagocytic Lymphohistiocytosis following Refractory Kawasaki Disease.

Hemophagocytic lymphohistiocytosis (HLH) is a systemic inflammatory disorder characterized by uncontrolled histiocytic proliferation, hemophagocytosis, macrophage activation, and up-regulation of inflammatory cytokines (Grom AA., Current opinion in rheumatology 2003; 15: 587-590). HLH is usually divided into two types: primary (familial) HLH and secondary (reactive) HLH. Primary HLH is associated with primary immune deficiencies in which specific gene mutations play an important role, such as perforin defects.

A novel de novo nonsense mutation in ZC4H2 causes Wieacker-Wolff Syndrome.

BACKGROUND: Wieacker-Wolff syndrome (WWS) is a congenital X-linked neuromuscular disorder, which was firstly reported in 1985. Zinc finger C4H2-type containing (ZC4H2) gene has been found to be associated with the disease pathogenesis. However, the underlying mechanism remains elusive. METHODS: Whole-exome sequencing was performed to identify the mutations. Expression plasmids were constructed and cell culture and immune-biochemical assays were used to examine the effects of the mutation. RESULTS: We reported a female patient with classical symptoms of WWS and discovered a novel nonsense heterozygous mutation (p.R67X; c.199C>T) in ZC4H2 gene in the patient but not in her parents. The mutation resulted in a 66 amino-acid truncated ZC4H2 protein. The mutation is located in the key helix domain and it altered the subcellular locations of the mutant ZC4H2 protein. X-chromosome inactivation (XCI) pattern analysis revealed that the XCI ratio of the proband was 22:78. CONCLUSION: Female heterozygous carriers with nonsense mutation with a truncated ZC4H2 protein could lead to the pathogenesis of Wieacker-Wolff syndrome and our study provides a potential new target for the disease treatment.

Transcriptional activation of USP16 gene expression by NFκB signaling.

Ubiquitin Specific Peptidase 16 (USP16) has been reported to contribute to somatic stem-cell defects in Down syndrome. However, how this gene being regulated is largely unknown. To study the mechanism underlying USP16 gene expression, USP16 gene promoter was cloned and analyzed by luciferase assay. We identified that the 5' flanking region (- 1856 bp ~ + 468 bp) of the human USP16 gene contained the functional promotor to control its transcription. Three bona fide NFκB binding sites were found in USP16 promoter. We showed that p65 overexpression enhanced endogenous USP16 mRNA level. Furthermore, LPS and TNFα, strong activators of the NFκB pathway, upregulated the USP16 transcription. Our data demonstrate that USP16 gene expression is tightly regulated at transcription level. NFκB signaling regulates the human USP16 gene expression through three cis-acting elements. The results provide novel insights into a potential role of dysregulation of USP16 expression in Alzheimer's dementia in Down Syndrome.

The prevalence and risk factors of abnormal circadian blood pressure in patients with IgA nephropathy
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AIMS: To investigate the prevalence and risk factors of abnormal circadian blood pressure (BP) rhythm among IgA nephropathy (IgAN) patients. MATERIALS AND METHODS: 375 Chinese IgAN patients with biopsy-proven primary IgAN were recruited from June 2013 to December 2014 and divided into four groups based on circadian BP rhythm (dippers, non-dippers, reversed dippers, and extreme dippers) measured by 24-hour ambulatory BP monitoring. Demographic and clinicopathologic data were collected and analyzed. RESULTS: The prevalence of abnormal circadian BP was 84% (315/375) in all the participants, accounting for 82.4% of the normotensive patients and 86.1% of the hypertensive patients. The prevalence increased with the decline of estimated glomerular filtration rate (eGFR) in IgAN patients. The non-dipper pattern was most frequent (63.8%, 201/315) in this population, followed by the reversed-dipper (27.3%, 86/315), and then the extreme-dipper pattern (8.9%, 28/315). Multivariate logistic regression analysis revealed that the eGFR (odds ratio (OR) = 0.64, 95% conficence interval (CI): 0.45 - 0.93, p = 0.037), serum uric acid (OR = 1.60, 95% CI: 1.01 - 2.54, p = 0.014), and small vessel hyalinosis (OR = 2.17, 95% CI: 1.14 - 4.11, p = 0.044) were independently associated with abnormal circadian BP rhythm. CONCLUSION: Abnormal circadian BP rhythm was common in IgAN patients and occurred in the early stages of chronic kidney disease. Low eGFR, high serum uric acid, and small vessel hyalinosis increased risk of abnormal BP rhythm in IgAN patients.
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Nutritional Deficiency in Early Life Facilitates Aging-Associated Cognitive Decline.

BACKGROUND: Nutrition is important for the fetal developmental programming. Nutritional deficiency in early life could increase the susceptibility to many aging-related disorders including cognitive decline. OBJECTIVE: Our study aims to investigate the effect of early famine exposure on aging-associated cognitive function. METHODS: We recruited 6790 subjects born between 1956 to 1964 during which the Great Chinese Famine occurred (1959-1961). Cognitive function of these subjects were evaluated using the Mini-Mental State Examination (MMSE), the Activities of Daily Living scale (ADL), the Instrumental Activities of Daily Living scale (IADL) and the Clinical Dementia Rating (CDR). RESULTS: Our study identified that early exposure to the famine significantly increased the risk of cognitive impairments in later life, leading to higher prevalence of Mild Cognitive Impairment (MCI) and dementia. We also found the sex and rural-urban differences in this malnutrition-induced effect. Illiteracy, history of stroke or diabetes mellitus are great risk factors to facilitate the cognitive decline. CONCLUSION: These findings demonstrate that exposure to famine during early life including prenatal period and early childhood facilitates aging-associated cognitive deficits.

Resveratrol relieves ischemia-induced oxidative stress in the hippocampus by activating SIRT1.

Resveratrol, a naturally occurring phytoalexin, acts as an activator of sirtuin 1 (SIRT1) and has been shown to have a neuroprotective role in various models. Healthy adult male Sprague-Dawley rats were subjected to cerebral ischemia in order to study the protective effect of resveratrol on the brain following ischemia, and to investigate the effects of SIRT1 activation on the hippocampus. Untreated and resveratrol-treated rats were anesthetized prior to undergoing surgery to induce middle cerebral artery occlusion followed by reperfusion. SIRT1 expression was evaluated by immunohistochemistry, western blotting and reverse transcription-quantitative polymerase chain reaction, and SIRT1 activity was also evaluated. In addition, terminal deoxynucleotidyl transferase dUTP nick end-labeling (TUNEL) and Nissl staining assays were conducted and the levels of reactive oxygen species were determined. It was observed that resveratrol significantly decreased the number of TUNEL-positive cells and increased the expression of SIRT1 mRNA in a dose-dependent manner. This was accompanied by increases in SIRT1 protein expression levels and SIRT1 activity. The results demonstrate the neuroprotective and antioxidant effects of resveratrol against ischemia-induced apoptosis in the rat hippocampus.

Long-term potentiation decay and memory loss are mediated by AMPAR endocytosis.

Long-term potentiation (LTP) of synaptic strength between hippocampal neurons is associated with learning and memory, and LTP dysfunction is thought to underlie memory loss. LTP can be temporally and mechanistically classified into decaying (early-phase) LTP and nondecaying (late-phase) LTP. While the nondecaying nature of LTP is thought to depend on protein synthesis and contribute to memory maintenance, little is known about the mechanisms and roles of decaying LTP. Here, we demonstrated that inhibiting endocytosis of postsynaptic α-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid receptors (AMPARs) prevents LTP decay, thereby converting it into nondecaying LTP. Conversely, restoration of AMPAR endocytosis by inhibiting protein kinase Mζ (PKMζ) converted nondecaying LTP into decaying LTP. Similarly, inhibition of AMPAR endocytosis prolonged memory retention in normal animals and reduced memory loss in a murine model of Alzheimer's disease. These results strongly suggest that an active process that involves AMPAR endocytosis mediates the decay of LTP and that inhibition of this process can prolong the longevity of LTP as well as memory under both physiological and pathological conditions.

[Adaptive changes of Zebrafish (Danio rerio) to anaerobic exercise training].

To explore adaptive changes of the Zebrafish (Danio rerio) to anaerobic exercise training as well as to collect basic data of molecular mechanisms of adaption to anaerobic exercise training among this fish, we investigated the influences of 4 weeks of anaerobic exercise training on the behavior, morphology, growth, muscle biochemical components and metabolic enzyme activities of the Zebrafish. Our results indicated that individual's daily activity level declined after 4 weeks training and they preferred to swim together more frequently. Both body length and weight gain decreased, allowing the fish to adapt to the increased locomotion. Similarly, glycogen in muscles increased and exercise endurance also strengthened due to the enhancement of energy storage. Moreover, although the activity of lactate dehydrogenase (LDH) in muscle has increased, the activity of citrate synthase (CS) decreased. Taken together, these results suggest that both the ability of anaerobic exercise and anaerobic metabolism of Zebrafish can in fact be enhanced by training, and the tangible changes that we could measure were retained, but only for a limited time.

Development of a ratiometric time-resolved luminescence sensor for pH based on lanthanide complexes.

Time-resolved luminescence bioassay technique using lanthanide complexes as luminescent probes/sensors has shown great utilities in clinical diagnostics and biotechnology discoveries. In this work, a novel terpyridine polyacid derivative that can form highly stable complexes with lanthanide ions in aqueous media, (4'-hydroxy-2,2':6',2''-terpyridine-6,6''-diyl) bis(methylenenitrilo) tetrakis(acetic acid) (HTTA), was designed and synthesized for developing time-resolved luminescence pH sensors based on its Eu(3+) and Tb(3+) complexes. The luminescence characterization results reveal that the luminescence intensity of HTTA-Eu(3+) is strongly dependent on the pH values in weakly acidic to neutral media (pK(a) = 5.8, pH 4.8-7.5), while that of HTTA-Tb(3+) is pH-independent. This unique luminescence response allows the mixture of HTTA-Eu(3+) and HTTA-Tb(3+) (the HTTA-Eu(3+)/Tb(3+) mixture) to be used as a ratiometric luminescence sensor for the time-resolved luminescence detection of pH with the intensity ratio of its Tb(3+) emission at 540 nm to its Eu(3+) emission at 610 nm, I(540 nm)/I(610 nm), as a signal. Moreover, the UV absorption spectrum changes of the HTTA-Eu(3+)/Tb(3+) mixture at different pHs (pH 4.0-7.0) also display a ratiometric response to the pH changes with the ratio of absorbance at 290 nm to that at 325 nm, A(290 nm)/A(325 nm), as a signal. This feature enables the HTTA-Eu(3+)/Tb(3+) mixture to have an additional function for the pH detection with the absorption spectrometry technique. For loading the complexes into the living cells, the acetoxymethyl ester of HTTA was synthesized and used for loading HTTA-Eu(3+) and HTTA-Tb(3+) into the cultured HeLa cells. The luminescence imaging results demonstrated the practical utility of the new sensor for the time-resolved luminescence cell imaging application.