Disruption of DNA-PKcs-mediated cGAS retention on damaged chromatin potentiates DNA damage-inducing agent-induced anti-multiple myeloma activity.

BACKGROUND: Targeting DNA damage repair factors, such as DNA-dependent protein kinase catalytic subunit (DNA-PKcs), may offer an opportunity for effective treatment of multiple myeloma (MM). In combination with DNA damage-inducing agents, this strategy has been shown to improve chemotherapies partially via activation of cGAS-STING pathway by an elevated level of cytosolic DNA. However, as cGAS is primarily sequestered by chromatin in the nucleus, it remains unclear how cGAS is released from chromatin and translocated into the cytoplasm upon DNA damage, leading to cGAS-STING activation. METHODS: We examined the role of DNA-PKcs inhibition on cGAS-STING-mediated MM chemosensitivity by performing mass spectrometry and mechanism study. RESULTS: Here, we found DNA-PKcs inhibition potentiated DNA damage-inducing agent doxorubicin-induced anti-MM effect by activating cGAS-STING signaling. The cGAS-STING activation in MM cells caused cell death partly via IRF3-NOXA-BAK axis and induced M1 polarization of macrophages. Moreover, this activation was not caused by defective classical non-homologous end joining (c-NHEJ). Instead, upon DNA damage induced by doxorubicin, inhibition of DNA-PKcs promoted cGAS release from cytoplasmic chromatin fragments and increased the amount of cytosolic cGAS and DNA, activating cGAS-STING. CONCLUSIONS: Inhibition of DNA-PKcs could improve the efficacy of doxorubicin in treatment of MM by de-sequestrating cGAS in damaged chromatin.

TREX2 enables efficient genome disruption mediated by paired CRISPR-Cas9 nickases that generate 3'-overhanging ends.

Paired SpCas9 nickases (SpCas9n) are an effective strategy to reduce off-target effect in genome editing. However, this approach is not efficient with 3'-overhanging ends, limiting its applications. In order to expand the utility of paired SpCas9n in genome editing, we tested the effect of the TREX2 3'-5' exonuclease on repair of 3'-overhanging ends. We found ectopic overexpression of Trex2 stimulates the efficiency of paired SpCas9n in genome disruption with 3'-overhanging ends up to 400-fold with little stimulation of off-target editing. TREX2 overexpressed preferentially deletes entire 3' overhangs but has no significant effect on 5' overhangs. Trex2 overexpression also stimulates genome disruption by paired SpCas9n that potentially generate short 3'-overhanging ends at overlapping SpCas9n target sites, suggesting sequential nicking of overlapping target sites by SpCas9n. This approach is further simplified with improved efficiency and safety by fusion of TREX2 and particularly its DNA-binding-deficient mutant to SpCas9n. Junction analysis at overlapping targets revealed the different extent of end resection of 3' single-stranded DNA (ssDNA) by free TREX2 and TREX2 fused to SpCas9n. SpCas9n-TREX2 fusion is more convenient and safer than overexpression of free TREX2 to process 3'-overhanging ends for efficient genome disruption by paired SpCas9n, allowing practical use of this TREX2-based strategy in genome editing.

Small extrachromosomal circular DNA harboring targeted tumor suppressor gene mutations supports intratumor heterogeneity in mouse liver cancer induced by multiplexed CRISPR/Cas9.

BACKGROUND: Primary liver cancer has significant intratumor genetic heterogeneity (IGH), which drives cancer evolution and prevents effective cancer treatment. CRISPR/Cas9-induced mouse liver cancer models can be used to elucidate how IGH is developed. However, as CRISPR/Cas9 could induce chromothripsis and extrachromosomal DNA in cells in addition to targeted mutations, we wondered whether this effect contributes to the development of IGH in CRISPR/Cas9-induced mouse liver cancer. METHODS: CRISPR/Cas9-based targeted somatic multiplex-mutagenesis was used to target 34 tumor suppressor genes (TSGs) for induction of primary liver tumors in mice. Target site mutations in tumor cells were analyzed and compared between single-cell clones and their subclones, between different time points of cell proliferation, and between parental clones and single-cell clones derived from mouse subcutaneous allografts. Genomic instability and generation of extrachromosomal circular DNA (eccDNA) was explored as a potential mechanism underlying the oscillation of target site mutations in these liver tumor cells. RESULTS: After efficiently inducing autochthonous liver tumors in mice within 30-60 days, analyses of CRISPR/Cas9-induced tumors and single-cell clones derived from tumor nodules revealed multiplexed and heterogeneous mutations at target sites. Many target sites frequently displayed more than two types of allelic variations with varying frequencies in single-cell clones, indicating increased copy number of these target sites. The types and frequencies of targeted TSG mutations continued to change at some target sites between single-cell clones and their subclones. Even the proliferation of a subclone in cell culture and in mouse subcutaneous graft altered the types and frequencies of targeted TSG mutations in the absence of continuing CRISPR/Cas9 genome editing, indicating a new source outside primary chromosomes for the development of IGH in these liver tumors. Karyotyping of tumor cells revealed genomic instability in these cells manifested by high levels of micronuclei and chromosomal aberrations including chromosomal fragments and chromosomal breaks. Sequencing analysis further demonstrated the generation of eccDNA harboring targeted TSG mutations in these tumor cells. CONCLUSIONS: Small eccDNAs carrying TSG mutations may serve as an important source supporting intratumor heterogeneity and tumor evolution in mouse liver cancer induced by multiplexed CRISPR/Cas9.

Proximal binding of dCas9 at a DNA double strand break stimulates homology-directed repair as a local inhibitor of classical non-homologous end joining.

In CRISPR/Cas9 genome editing, the tight and persistent target binding of Cas9 provides an opportunity for efficient genetic and epigenetic modification on genome. In particular, technologies based on catalytically dead Cas9 (dCas9) have been developed to enable genomic regulation and live imaging in a site-specific manner. While post-cleavage target residence of CRISPR/Cas9 could alter the pathway choice in repair of Cas9-induced DNA double strand breaks (DSBs), it is possible that dCas9 residing adjacent to a break may also determine the repair pathway for this DSB, providing an opportunity to control genome editing. Here, we found that loading dCas9 onto a DSB-adjacent site stimulated homology-directed repair (HDR) of this DSB by locally blocking recruitment of classical non-homologous end-joining (c-NHEJ) factors and suppressing c-NHEJ in mammalian cells. We further repurposed dCas9 proximal binding to increase HDR-mediated CRISPR genome editing by up to 4-fold while avoiding exacerbation of off-target effects. This dCas9-based local inhibitor provided a novel strategy of c-NHEJ inhibition in CRISPR genome editing in place of small molecule c-NHEJ inhibitors, which are often used to increase HDR-mediated genome editing but undesirably exacerbate off-target effects.

Correlation analysis and benchmark dose study on bone metabolic biochemical index of low doses of exposed hydrogen fluoride workers / 中华劳动卫生职业病杂志

Objective: To analyze correlation of occupational hydrogen fluoride exposure to low doses of bone metabolism index through occupational epidemiological investigation and benchmark dose calculation. Methods: In May 2021, using cluster sampling method, 237 workers exposed to hydrogen fluoride in a company were selected as the contact group, and 83 workers not exposed to hydrogen fluoride in an electronics production company were selected as the control group. The external exposure dose and urinary fluoride concentration, blood and urine biochemical indicators of the workers was measured.The relationship between external dose and internal dose of hydrogen fluoride was analyzed. The external dose, urinary fluoride was used as exposure biomarkers, while serum osteocalcin (BGP), serum alkaline phosphatase (AKP) and urinary hydroxyproline (HYP) were used as effect biomarkers for bone metabolism of hydrogen fluoride exposure. The benchmark dose calculation software (BMDS1.3.2) was used to calculate benchmark dose (BMD) . Results: Urine fluoride concentration in the contact group was correlated with creatinine-adjusted urine fluoride concentration (r=0.69, P=0.001). There was no significant correlation between the external dose of hydrogen fluoride and urine fluoride in the contact group (r=0.03, P=0.132). The concentrations of urine fluoride in the contact group and the control group were (0.81±0.61) and (0.45±0.14) mg/L, respectively, and the difference between the two groups was statistically significant (t=5.01, P=0.025). Using BGP, AKP and HYP as effect indexes, the urinary BMDL-05 values were 1.28, 1.47 and 1.08 mg/L, respectively. Conclusion: Urinary fluoride can sensitively reflect the changes in the effect indexes of biochemical indexes of bone metabolism. BGP and HYP can be used as early sensitive effect indexes of occupational hydrogen fluoride exposure.

Target residence of Cas9-sgRNA influences DNA double-strand break repair pathway choices in CRISPR/Cas9 genome editing.

BACKGROUND: Due to post-cleavage residence of the Cas9-sgRNA complex at its target, Cas9-induced DNA double-strand breaks (DSBs) have to be exposed to engage DSB repair pathways. Target interaction of Cas9-sgRNA determines its target binding affinity and modulates its post-cleavage target residence duration and exposure of Cas9-induced DSBs. This exposure, via different mechanisms, may initiate variable DNA damage responses, influencing DSB repair pathway choices and contributing to mutational heterogeneity in genome editing. However, this regulation of DSB repair pathway choices is poorly understood. RESULTS: In repair of Cas9-induced DSBs, repair pathway choices vary widely at different target sites and classical nonhomologous end joining (c-NHEJ) is not even engaged at some sites. In mouse embryonic stem cells, weakening the target interaction of Cas9-sgRNA promotes bias towards c-NHEJ and increases target dissociation and reduces target residence of Cas9-sgRNAs in vitro. As an important strategy for enhancing homology-directed repair, inactivation of c-NHEJ aggravates off-target activities of Cas9-sgRNA due to its weak interaction with off-target sites. By dislodging Cas9-sgRNA from its cleaved targets, DNA replication alters DSB end configurations and suppresses c-NHEJ in favor of other repair pathways, whereas transcription has little effect on c-NHEJ engagement. Dissociation of Cas9-sgRNA from its cleaved target by DNA replication may generate three-ended DSBs, resulting in palindromic fusion of sister chromatids, a potential source for CRISPR/Cas9-induced on-target chromosomal rearrangements. CONCLUSIONS: Target residence of Cas9-sgRNA modulates DSB repair pathway choices likely through varying dissociation of Cas9-sgRNA from cleaved DNA, thus widening on-target and off-target mutational spectra in CRISPR/Cas9 genome editing.

DNA nicks induce mutational signatures associated with BRCA1 deficiency.

Analysis of human cancer genome sequences has revealed specific mutational signatures associated with BRCA1-deficient tumors, but the underlying mechanisms remain poorly understood. Here, we show that one-ended DNA double strand breaks (DSBs) converted from CRISPR/Cas9-induced nicks by DNA replication, not two-ended DSBs, cause more characteristic chromosomal aberrations and micronuclei in Brca1-deficient cells than in wild-type cells. BRCA1 is required for efficient homologous recombination of these nick-converted DSBs and suppresses bias towards long tract gene conversion and tandem duplication (TD) mediated by two-round strand invasion in a replication strand asymmetry. However, aberrant repair of these nick-converted one-ended DSBs, not that of two-ended DSBs in Brca1-deficient cells, generates mutational signatures such as small indels with microhomology (MH) at the junctions, translocations and small MH-mediated TDs, resembling those in BRCA1-deficient tumors. These results suggest a major contribution of DNA nicks to mutational signatures associated with BRCA1 deficiency in cancer and the underlying mechanisms.

Harnessing accurate non-homologous end joining for efficient precise deletion in CRISPR/Cas9-mediated genome editing.

BACKGROUND: Many applications of CRISPR/Cas9-mediated genome editing require Cas9-induced non-homologous end joining (NHEJ), which was thought to be error prone. However, with directly ligatable ends, Cas9-induced DNA double strand breaks may be repaired preferentially by accurate NHEJ. RESULTS: In the repair of two adjacent double strand breaks induced by paired Cas9-gRNAs at 71 genome sites, accurate NHEJ accounts for about 50% of NHEJ events. This paired Cas9-gRNA approach underestimates the level of accurate NHEJ due to frequent + 1 templated insertions, which can be avoided by the predefined Watson/Crick orientation of protospacer adjacent motifs (PAMs). The paired Cas9-gRNA strategy also provides a flexible, reporter-less approach for analyzing both accurate and mutagenic NHEJ in cells and in vivo, and it has been validated in cells deficient for XRCC4 and in mouse liver. Due to high frequencies of precise deletions of defined "3n"-, "3n + 1"-, or "3n + 2"-bp length, accurate NHEJ is used to improve the efficiency and homogeneity of gene knockouts and targeted in-frame deletions. Compared to "3n + 1"-bp, "3n + 2"-bp can overcome + 1 templated insertions to increase the frequency of out-of-frame mutations. By applying paired Cas9-gRNAs to edit MDC1 and key 53BP1 domains, we are able to generate predicted, precise deletions for functional analysis. Lastly, a Plk3 inhibitor promotes NHEJ with bias towards accurate NHEJ, providing a chemical approach to improve genome editing requiring precise deletions. CONCLUSIONS: NHEJ is inherently accurate in repair of Cas9-induced DNA double strand breaks and can be harnessed to improve CRISPR/Cas9 genome editing requiring precise deletion of a defined length.

H2AX facilitates classical non-homologous end joining at the expense of limited nucleotide loss at repair junctions.

Phosphorylated histone H2AX, termed 'γH2AX', mediates the chromatin response to DNA double strand breaks (DSBs) in mammalian cells. H2AX deficiency increases the numbers of unrepaired DSBs and translocations, which are partly associated with defects in non-homologous end joining (NHEJ) and contributing to genomic instability in cancer. However, the role of γH2AX in NHEJ of general DSBs has yet to be clearly defined. Here, we showed that despite little effect on overall NHEJ efficiency, H2AX deficiency causes a surprising bias towards accurate NHEJ and shorter deletions in NHEJ products. By analyzing CRISPR/Cas9-induced NHEJ and by using a new reporter for mutagenic NHEJ, we found that γH2AX, along with its interacting protein MDC1, is required for efficient classical NHEJ (C-NHEJ) but with short deletions and insertions. Epistasis analysis revealed that ataxia telangiectasia mutated (ATM) and the chromatin remodeling complex Tip60/TRRAP/P400 are essential for this H2AX function. Taken together, these data suggest that a subset of DSBs may require γH2AX-mediated short-range nucleosome repositioning around the breaks to facilitate C-NHEJ with loss of a few extra nucleotides at NHEJ junctions. This may prevent outcomes such as non-repair and translocations, which are generally more destabilizing to genomes than short deletions and insertions from local NHEJ.

Study on distribution status of Oncomelania hupensis-intermediate host of Schistosoma japonicum in Jiangxi Province I Analysis of distribution of O. hupen-sis in Poyang Lake area / 中国血吸虫病防治杂志

Objective To grasp the distribution status of Oncomelania hupensis snails in Poyang Lake area,so as to provide the evidence for formulating and adjusting the schistosomiasis prevention and control strategy in lake areas. Methods The vec-tor grid was created and sampled randomly by 200 m × 200 m in the spatial database of grassland,and the distribution of snails was investigated in the selected grid by using the method of mechanical sampling by 50 m × 50 m. At the same time,the eleva-tion of investigation points was extracted based on the topographic map of Poyang Lake. Results Totally 949 and 210 investiga-tion points were collected from the south and north of Poyang Lake areas,accounting for 3.04%and 3.21%of all the investiga-tion points in the respective region. The number of investigation points,the appearance rate of snail frame,and the average den-sity of alive snails were 15231,8.15%,and 0.463/0.1 m2,respectively. The elevation of snail distribution area of the south and north Poyang Lake areas were 11-16 m and 9-16 m respectively. The elevation of concentrated snail belts of the south Poyang Lake area were 12-13 m and 15-16 m,and the elevation of concentrated snail belts of the north Poyang Lake area was 12-14 m. Conclusions The distribution of snails is in the range of 9-16 m. The suitable habitats of snail breeding are moving from the south Poyang Lake area to the north Poyang Lake area,and from high elevation to low elevation. In the future,the schistosomia-sis prevention and control measures could be formulated based on the geographical characteristics of current snail distribution in order to consolidate the achievements of schistosomiasis control.

Role of new strategy in transmission control of schistosomiasis in Poyang Lake region / 中国血吸虫病防治杂志

Objective To evaluate the role of new strategy in the transmission control of schistosomiasis in Poyang Lake re-gion. Methods The information and epidemic data of schistosomiasis control were collected and analyzed in Poyang Lake re-gion from 2005 to 2016. Results After eleven years of carrying out the new strategy,thirteen counties achieved the objective of transmission control in Poyang Lake region. In 2016,the number of schistosomiasis cases and human infection rate were 10301 and 0.03％,decreased by 89.64％and 99.45％compared with those in 2005,respectively. The number of cattle and schistosome-infected cattle were 68152 and 5,decreased by 50.84％and 99.83％compared with those in 2005,respectively. The average density of Oncomelania hupensis snails was decreased by 61.52％. No schistosome-infected snails were found since 2014. Con-clusion The new strategy accurately locates the key points and targets of schistosomiasis transmission chain ,which has con-trolled the human and animal's fecal eggs from polluting grassland,and cut off the transmission chain,reduced both the infec-tion rates of human and animal and the re-infection risk,and promoted to achieve the target of schistosomiasis transmission con-trol in Poyang Lake region.

Circulating tumor DNA in hepatocellular carcinoma: trends and challenges.

Molecular characterization of individual patients' tumor cells is becoming increasingly important in offering effective treatment for patients in clinical practice. Recent advances in the field have indicated that circulating tumor DNA (ctDNA) has huge potential to serve as a biomarker for early detection and precision treatment as well as prognosis of hepatocellular carcinoma (HCC). As ctDNA in HCC patients harbors the molecular characteristics of HCC tumor cells, ctDNA analysis in the blood may be sufficient for convenient, non-invasive and accurate detection, providing information for HCC diagnosis, treatment and prognosis. In this review, we will summarize and discuss current trends and challenges of ctDNA application in HCC.

Buried territories: heterochromatic response to DNA double-strand breaks.

Cellular response to DNA double-strand breaks (DSBs), the most deleterious type of DNA damage, is highly influenced by higher-order chromatin structure in eukaryotic cells. Compared with euchromatin, the compacted structure of heterochromatin not only protects heterochromatic DNA from damage, but also adds an extra layer of control over the response to DSBs occurring in heterochromatin. One key step in this response is the decondensation of heterochromatin structure. This decondensation process facilitates the DNA damage signaling and promotes proper heterochromatic DSB repair, thus helping to prevent instability of heterochromatic regions of genomes. This review will focus on the functions of the ataxia telangiectasia mutated (ATM) signaling cascade involving ATM, heterochromatin protein 1 (HP1), Krüppel-associated box (KRAB)-associated protein-1 (KAP-1), tat-interacting protein 60 (Tip60), and many other protein factors in DSB-induced decondensation of heterochromatin and subsequent repair of heterochromatic DSBs. As some subsets of DSBs may be repaired in heterochromatin independently of the ATM signaling, a possible repair model is also proposed for ATM-independent repair of these heterochromatic DSBs.

Autophagy in 5-Fluorouracil Therapy in Gastrointestinal Cancer: Trends and Challenges.

OBJECTIVE: 5-Fluorouracil (5-FU)-based combination therapies are standard treatments for gastrointestinal cancer, where the modulation of autophagy is becoming increasingly important in offering effective treatment for patients in clinical practice. This review focuses on the role of autophagy in 5-FU-induced tumor suppression and cancer therapy in the digestive system. DATA SOURCES: All articles published in English from 1996 to date those assess the synergistic effect of autophagy and 5-FU in gastrointestinal cancer therapy were identified through a systematic online search by use of PubMed. The search terms were "autophagy" and "5-FU" and ("colorectal cancer" or "hepatocellular carcinoma" or "pancreatic adenocarcinoma" or "esophageal cancer" or "gallbladder carcinoma" or "gastric cancer"). STUDY SELECTION: Critical reviews on relevant aspects and original articles reporting in vitro and/or in vivo results regarding the efficiency of autophagy and 5-FU in gastrointestinal cancer therapy were reviewed, analyzed, and summarized. The exclusion criteria for the articles were as follows: (1) new materials (e.g., nanomaterial)-induced autophagy; (2) clinical and experimental studies on diagnostic and/or prognostic biomarkers in digestive system cancers; and (3) immunogenic cell death for anticancer chemotherapy. RESULTS: Most cell and animal experiments showed inhibition of autophagy by either pharmacological approaches or via genetic silencing of autophagy regulatory gene, resulting in a promotion of 5-FU-induced cancer cells death. Meanwhile, autophagy also plays a pro-death role and may mediate cell death in certain cancer cells where apoptosis is defective or difficult to induce. The dual role of autophagy complicates the use of autophagy inhibitor or inducer in cancer chemotherapy and generates inconsistency to an extent in clinic trials. CONCLUSION: Autophagy might be a therapeutic target that sensitizes the 5-FU treatment in gastrointestinal cancer.

Short-term efficacy of treating hepatitis B virus-related acute-on-chronic liver failure based on cold pattern differentiation with hot herbs: A randomized controlled trial / 中国结合医学杂志

<p><b>OBJECTIVE</b>To evaluate the clinical efficacy and safety of Yinchen Zhufu Decoction (, YCZFD) in the treatment of acute-on-chronic liver failure caused by hepatitis B virus (HBV-ACLF) with cold pattern in Chinese medicine (CM).</p><p><b>METHODS</b>This is a multi-center randomized controlled trial of integrative treatment of CM and Western medicine (WM) for the management of HBV-ACLF patients. A total of 200 HBV-ACLF patients with cold pattern were equally randomly assigned to receive YCZFD and WM (integrative treatment) or WM conventional therapy alone respectively for 4 weeks. The primary end point was the mortality for HBV-ACLF patients. Secondary outcome measures included Model for End-Stage Liver disease (MELD) score, liver biochemical function, coagulation function and complications. Adverse events during treatment were reported.</p><p><b>RESULTS</b>The mortality was decreased 14.28% in the integrative treatment group compared with WM group (χ(2) =6.156, P=0.013). The integrative treatment was found to signifificantly improve the MELD score (t=2.353, P=0.020). There were statistically signifificant differences in aspartate transaminase, total bilirubin, indirect bilirubin, direct bilirubin and prothrombin time between the two groups (P<0.05 or P<0.01). The complications of ascites (χ(2)=9.033, P=0.003) and spontaneous bacteria peritonitis (χ(2)=4.194, P=0.041) were improved signifificantly in the integrative treatment group. No serious adverse event was reported.</p><p><b>CONCLUSIONS</b>The integrative treatment of CM and WM was effective and safe for HBV-ACLF patients with cold pattern in CM. The Chinese therapeutic principle "treating cold pattern with hot herbs" remains valuable to the clinical therapy. (Trial registration No. ChiCTR-TRC-10000766).</p>

Syndrome classification based on manifold ranking for viral hepatitis / 中国结合医学杂志

Treatment determination based on syndrome differentiation is the key of Chinese medicine. A feasible way of improving the clinical therapy effectiveness is needed to correctly differentiate the syndrome classifications based on the clinical manifestations. In this paper, a novel data mining method based on manifold ranking (MR) is proposed to explore the relation between syndromes and symptoms for viral hepatitis. Since MR could take the symptom data with expert differentiation and the symptom data without expert differentiation into the task of syndrome classification, the clinical information used for modeling the syndrome features is greatly enlarged so as to improve the precise of syndrome classification. In addition, the proposed method of syndrome classification could also avoid two disadvantages in previous methods: linear relation of the clinical data and mutually exclusive symptoms among different syndromes. And it could help exploit the latent relation between syndromes and symptoms more effectively. Better performance of syndrome classification is able to be achieved according to the experimental results and the clinical experts.

An epidemiological study of food intolerance in 2434 children / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To investigate the epidemiological characteristics of intolerance to 14 foods in children and the relationship between food intolerance and disease of various systems.</p><p><b>METHODS</b>Serum samples of 2434 children with diseases were collected for food intolerance testing between January 2009 and October 2012. Allergen-specific IgG antibodies to 14 foods were detected using enzyme-linked immunosorbent assay. The children's intolerance to different foods and its relationship with age, sex and disease of various systems were analyzed.</p><p><b>RESULTS</b>Among these children, positive rates of intolerance to milk and eggs were as high as 74.16% and 66.47% respectively, while positive rates of intolerance to chicken and pork were relatively low (0.29% and 0.21% respectively). The overall positive rates of food intolerance were 12.579% and 12.470% in males and females respectively. For infants, the highest intolerance rate was to milk; for preschool and school-age children, the highest intolerance rates were to milk and eggs respectively; for children in adolescence, the highest intolerance rate was to eggs. Among children with food intolerance involving single system, those with developmental abnormality or immune system disease had the highest overall positive rate of food intolerance. Children with double-system diseases had an overall positive rate of food intolerance as high as 13.393%. Among the children involving various systems, the positive rate of intolerance to milk and eggs were higher than other food.</p><p><b>CONCLUSIONS</b>Factors influencing food intolerance in children include food categories and age. There may be a relationship between food intolerance and disease of various systems, and this is significant to the growth and development of children.</p>

Deferoxamine induces apoptosis of K562 cells / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To study the molecular mechanism of apoptosis of leukemic cells (K562 cells) induced by iron chelating agent deferoxamine (DFO).</p><p><b>METHODS</b>The exponentially growing K562 cells were used (1×10(6)/mL) in this study. The K562 cells were treated with different concentrations of DFO (10, 50 and 100 mmol/L), DFO+FeCl3 (10 μmol/L each) or normal saline (blank control). The cellular labile iron pool was measured with a fluorimetric assay using the metalsensitive probe calcein-AM. The viable count and cell viability were determined by typanblue assay. Cell apoptosis was determined by morphological study and flow cytometry assay. Caspase-3 activity in K562 cells was detected by colorimetry.</p><p><b>RESULTS</b>After DFO treatment, the cellular labile iron pool and the viability of K562 cells were reduced and the cell apoptosis increased in a time- and dose-dependent manner compared with the blank control group. The apoptosis rate of K562 cells in the DFO+FeCl3 treatment group was not significantly different from that in the blank control group. The caspase-3 activity in K562 cells increased significantly 24 hrs after 50 and 100 μmmol DFO treatment when compared with the blank control group (P<0.01). There was a negative correlation between cellular labile iron pool and caspase-3 activity of K562 cells (r=-0.894, P<0.05).</p><p><b>CONCLUSIONS</b>DFO induces apoptosis of leukemic cells possibly through decreasing cellular labile iron pool and increasing caspase-3 activity of the cells.</p>

Expression of HSP70 mRNA and MDR1 mRNA in K562 cells induced by heat shock and ADM / 中国实验血液学杂志

This study was purpose to investigate the expression levels of HSP70 and MDR1 genes under heat shock and/or adriamycin (ADM) chemotherapy stimulation. The K562 cells were bathed in water at 43 degrees C for 1 hour, then the heat-treated K562 cells were collected and were cultured at 37 degrees C. The expression of HSP70 was assayed by immunocytochemistry, the growth suppression rate of K562 cells was detected by MTT assay, the function of P-gp and the expressions of HSP70 mRNA, MDR1 mRNA were detected by flow cytometry and real-time quantitative PCR (RT-PCR) respectively. The results showed that (1) the synthesis of HSP70 protein in K562 cells treated with high shock (43 degrees C) reached to high level after culture at 37 degrees C for 2 hours, and moved from cytoplasm to nucleolus, the expression of HSP70 began to decrease following 3 hours of culture at 37 degrees C, and gradually reached to normal level after culture at 37 degrees C for 5 hours, the location of HSP70 expression returned to cytoplasm; (2) the expressions of HSP70 mRNA and MDR1 mRNA increased following 43 degrees C heat shock, and were 4 and 5.8 times higher than that of control group at 37 degrees C culture for 2 hours respectively; (3) the expression of P-gp was higher in ADM group than that in control. The expressions of HSP mRNA and MDR1 mRNA increased significantly in heat shock plus ADM group and ADM group as compared with control (p<0.01). It is concluded that the heat shock and ADM chemotherapy both induce over expression of HSP70 and MDR1 which can maintain stability of K562 cells and may be related to formation of the MDR in leukemia.

Comparative study on clinical features between TEL-AML1 positive and negative childhood acute lymphoblastic leukemia / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To determine the incidence of TEL-AML1 fusion gene in childhood acute lymphoblastic leukemia (ALL) and to compare the clinical features between TEL-AML1 positive and negative patients.</p><p><b>METHODS</b>Samples of bone marrow or peripheral blood were collected from 95 newly diagnosed ALL children and the TEL-AML1 fusion gene was detected using nested reverse transcription-polymerase chain reaction (RT-PCR). The ALL patients were stratified into TEL-AML1 positive and negative groups and the clinical features were compared.</p><p><b>RESULTS</b>Among 95 patients, 20 (21.05%) were TEL-AML1 positive. The median age of TEL-AML1 positive patients was 5.9 years old and M/F ratio was 1.22:1. There were significant differences between TEL-AML1 positive and negative patients in hepatomegaly (2.75 cm vs. 4 cm below costal arch, P=0.006), splenomegaly (0 cm vs. 3 cm below costal arch, P < 0.001), initial white blood cell count (median 7.40 x 10(9)/L vs.18.70 x 10(9)/L, P=0.011), initial peripheral blood blast (median 2.45 x 10(9)/L vs.11.66 x 10(9)/L, P=0.013), hemoglobin level [(61.45 +/- 13.46) g/L vs. (75.89 +/- 23.11) g/L, P=0.003] and serum lactate dehydrogenase [(621.47 +/- 335.85) U/L vs.(1566.64 +/- 1720.45) U/L, P=0.020], while no differences were found between two groups in age, gender ratio, initial platelet count, percentage of blast in bone marrow, immunophenotypes and the expression of myeloid antigen CD13, CD33 and CD34. The prednisone sensitivity test showed that all 12 TEL-AML1 positive patients were good responders, while there were 11 prednisone poor responders among 40 negative patients (27.50%, P < 0.05). Bone marrow examination on day 15 showed no difference in the rate of complete remission between TEL-AML1 positive and negative patients.</p><p><b>CONCLUSION</b>The incidence of TEL-AML1 fusion gene in cases of ALL is 21.05%. The load of leukemia cells in TEL-AML1 positive patients is significantly smaller than its counterparts, and the blast cells in TEL-AML1 positive patients are more sensitive to prednisone, indicating childhood ALL with TEL-AML1 fusion gene has a favorable prognosis.</p>