DNA methylation promotes the expression of PPARγ transcript 1 at least in part by preventing NRF1 binding to the promoter P1 of chicken PPARγ gene

Peroxisome proliferator-activated receptor gamma (PPARγ) is a master regulator of adipogenesis. Our previous study revealed that chicken PPARγ has 3 alternative promoters named as P1, P2, and P3, and the DNA methylation of promoter P3 was negatively associated with PPARγ mRNA expression in abdominal adipose tissue (AAT). However, the methylation status of promoters P1 and P2 is unclear. Here we assessed promoter P1 methylation status in AAT of Northeast Agricultural University broiler lines divergently selected for abdominal fat content (NEAUHLF). The results showed that promoter P1 methylation differed in AAT between the lean and fat lines of NEAUHLF at 7 wk of age (p < 0.05), and AAT expression of PPARγ transcript 1 (PPARγ1), which was derived from the promoter P1, was greatly higher in fat line than in lean line at 2 and 7 wk of age. The results of the correlation analysis showed that P1 methylation was positively correlated with PPARγ1 expression at 7 wk of age (Pearson's r = 0.356, p = 0.0242), suggesting P1 methylation promotes PPARγ1 expression. To explore the underlying molecular mechanism of P1 methylation on PPARγ1 expression, bioinformatics analysis, dual-luciferase reporter assay, pyrosequencing, and electrophoresis mobility shift assay (EMSA) were performed. The results showed that transcription factor NRF1 repressed the promoter activity of the unmethylated P1, but not the methylated P1. Of all the 4 CpGs (CpG48, CpG49, CpG50, and CpG51), which reside within or nearby the NRF1 binding sites of the P1, only CpG49 methylation in AAT was remarkably higher in the fat line than in lean line at 7 wk of age (3.18 to 0.57, p < 0.05), and CpG49 methylation was positively correlated with PPARγ1 expression (Pearson's r = 0.3716, p = 0.0432). Furthermore, EMSA showed that CpG49 methylation reduced the binding of NRF1 to the P1. Taken together, our findings illustrate that P1 methylation promotes PPARγ1 expression at least in part by preventing NRF1 from binding to the promoter P1.

[Analysis of the effect of gene mutations on the efficacy of ruxolitinib in patients with myelofibrosis based on second-generation sequencing technology]

Objective: To assess the effect of gene mutations on the efficacy of ruxolitinib for treating myelofibrosis (MF) . Methods: We retrospectively analyzed the clinical data of 56 patients with MF treated with ruxolitinib from July 2017 to December 2020 and applied second-generation sequencing (NGS) technology to detect 127 hematologic tumor-related gene mutations. Additionally, we analyzed the relationship between mutated genes and the efficacy of ruxolitinib. Results: ①Among the 56 patients, there were 36 cases of primary bone marrow fibrosis (PMF) , 9 cases of bone marrow fibrosis (ppv-mf) after polycythemia vera, and 11 cases of bone marrow fibrosis (PET-MF) after primary thrombocytosis (ET) . ②Fifty-six patients with MF taking ruxolitinib underwent NGS, among whom, 50 (89.29%) carried driver mutations, 22 (39.29%) carried ≥3 mutations, and 29 (51.79%) carried high-risk mutations (HMR) . ③ For patients with MF carrying ≥ 3 mutations, ruxolitinib still had a better effect of improving somatic symptoms and shrinking the spleen (P=0.001, P<0.001) , but TTF and PFS were significantly shorter in patients carrying ≥ 3 mutations (P=0.007, P=0.042) . ④For patients carrying ≥ 2 HMR mutations, ruxolitinib was less effective in shrinking the spleen than in those who did not carry HMR (t= 10.471, P=0.034) , and the TTF and PFS were significantly shorter in patients carrying ≥2 HMR mutations (P<0.001, P=0.001) . ⑤Ruxolitinib had poorer effects on spleen reduction, symptom improvement, and stabilization of myelofibrosis in patients carrying additional mutations in ASXL1, EZH2, and SRSF2. Moreover, patients carrying ASXL1 and EZH2 mutations had significantly shorter TTF [ASXL1: 360 (55-1270) d vs 440 (55-1268) d, z=-3.115, P=0.002; EZH2: 327 (55-975) d vs 404 (50-1270) d, z=-3.219, P=0.001], and significantly shorter PFS compared to non-carriers [ASXL1: 457 (50-1331) d vs 574 (55-1437) d, z=-3.219, P=0.001) ; 428 (55-1331) d vs 505 (55-1437) d, z=-2.576, P=0.008]. Conclusion: The type and number of mutations carried by patients with myelofibrosis and HMR impact the efficacy of ruxolitinib.

[Course of disease and related epidemiological parameters of COVID-19: a prospective study based on contact tracing cohort]

Objective: To analyze the course of disease and epidemiological parameters of COVID-19 and provide evidence for making prevention and control strategies. Methods: To display the distribution of course of disease of the infectors who had close contacts with COVID-19 cases from January 1 to March 15, 2020 in Guangdong Provincial, the models of Lognormal, Weibull and gamma distribution were applied. A descriptive analysis was conducted on the basic characteristics and epidemiological parameters of course of disease. Results: In total, 515 of 11 580 close contacts were infected, with an attack rate about 4.4%, including 449 confirmed cases and 66 asymptomatic cases. Lognormal distribution was fitting best for latent period, incubation period, pre-symptomatic infection period of confirmed cases and infection period of asymptomatic cases; Gamma distribution was fitting best for infectious period and clinical symptom period of confirmed cases; Weibull distribution was fitting best for latent period of asymptomatic cases. The latent period, incubation period, pre-symptomatic infection period, infectious period and clinical symptoms period of confirmed cases were 4.50 (95%CI:3.86-5.13) days, 5.12 (95%CI:4.63-5.62) days, 0.87 (95%CI:0.67-1.07) days, 11.89 (95%CI:9.81-13.98) days and 22.00 (95%CI:21.24-22.77) days, respectively. The latent period and infectious period of asymptomatic cases were 8.88 (95%CI:6.89-10.86) days and 6.18 (95%CI:1.89-10.47) days, respectively. Conclusion: The estimated course of COVID-19 and related epidemiological parameters are similar to the existing data.

[Correlation between nUGT1A1 gene polymorphisms and adverse events of irinotecan plus S-1 for patients with recurrent or metastatic esophageal squamous cell carcinoma: a prospective, open-label, randomized controlled trial (ESWN 01)]

Objective: To investigate the correlation between UGT1A1 polymorphisms and the irinotecan plus S-1 regimen-induced toxicities in Chinese advanced esophageal squamous cell carcinoma (ESCC) patients. Methods: A total of 46 recurrent or metastatic ESCC patients selected from ESWN 01 trial were randomly assigned to irinotecan plus S-1 group [intravenous infusion of irinotecan (160 mg/m(2)) on day 1 and oral S-1 (80-120 mg) on days 1-10, repeated every 14 days]. Peripheral venous blood at baseline was collected and genomic DNA was extracted. The genetic polymorphisms of UGT1A1*6 and UGT1A1*28 were analyzed by polymerase chain reaction (PCR) amplification. Irinotecan plus S-1 regimen-induced toxicities of patients with different UGT1A1 polymorphisms were observed. The correlation between UGT1A1 polymorphisms and the adverse effects was analyzed. Results: Among the 46 patients, the numbers of UGT1A1*6 wild type genotype (GG), mutant heterozygote (GA) and mutant homozygote (AA) were 30, 15 and 1, while those with UGT1A1*28 wild type genotype (TA6/6), mutant heterozygote (TA6/7) and mutant homozygote (TA7/7) were 36, 8 and 2, respectively. Only one patient with UGT1A1*6 AA genotype occurred grade 3 diarrhea, while one of the 2 patients with UGT1A1*28 TA7/7 genotype occurred grade 4 diarrhea. No neutropenia was observed in the patient with UGT1A1*6 AA genotype, however, both of the two patients with UGT1A1*28 TA7/7 genotype occurred grade 3-4 neutropenia. Patients with UGT1A1*28 genetic polymorphism (TA 6/7 or TA7/7) had a higher response rate compared with wild-type TA6/6 carriers. (55.6% versus 26.5%). Conclusions: The homozygous genotype of UGT1A1*6 AA and UGT1A1*28 TA7/7 are rare (<5%) in Chinese ESCC population. Not all homozygous AA and TA7/7 carriers occur severe dose limited toxicities (DLT) when treated with irinotecan (160 mg/m(2)) plus S-1 regimen for 2 weeks. However, it's still necessary torigorously observe the occurrence of severe diarrhea and neutropenia in patients with UGT1A1*6 AA and UGT1A1*28 TA7/7 and adjust the dose timely.

[Analysis of gene mutations and clinic features in 108 patients with myeloproliferative neoplasm]

Objective: To analyze the genetic mutations and clinical features of the subtypes of classical BCR-ABL-negative myeloproliferative neoplasm (MPN) . Methods: Mutations of 108 newly diagnosed BCR-ABL-negative MPN patients [including 55 patients with essential thrombocytopenia (ET) , 24 with polycythemia vera (PV) , and 29 with primary myelofibrosis (PMF) ] were identified using next-generation sequencing with 127-gene panel, and the relationship between gene mutations and clinical features were analyzed. Results: Total 211 mutations in 32 genes were detected in 100 MPN patients (92.59% ) , per capita carried (1.96±1.32) mutations. 85.19% (92/108) patients carried the driver gene (JAK2, CALR, MPL) mutations, 69.56% (64/92) of these patients carried at least 1 additional gene mutation. In descending order of mutation frequency, the highest frequency was for activation signaling pathway genes (42.2% , 89/211) , methylation genes (17.6% , 36/211) , and chromatin-modified genes (16.1% , 34/211) . There was a significant difference in the number of mutations in the activation signaling pathway genes, epigenetic regulatory genes, spliceosomes, and RNA metabolism genes among the three MPN subgroups. The average number of additional mutations in PMF patients was higher than that in ET and PV patients (1.69±1.39, 0.67±0.70, 0.87±1.22, χ(2)=13.445, P=0.001) . MPN-SAF-TSS (MPN 10 score) (P=0.006) and myelofibrosis level (P=0.015) in patients with ≥ 3 mutant genes were higher and the HGB level (P=0.002) was lower than in those with<3 mutations. Twenty-six patients (24.1% ) carried high-risk mutation (HMR) , and patients with HMR had lower PLT (P=0.017) , HGB levels (P<0.001) , and higher myelofibrosis level (P=0.010) and MPN10 score (P<0.001) . The frequency of ASXL1 mutations was higher in PMF than in PV patients (34.5% vs. 4.2% , P=0.005) . PMF patients with ASXL1 had lower levels of PLT and HGB (P=0.029 and 0.019) . Conclusion: 69.56% of MPN patients carry at least one additional mutation, and 24.1% patients had HMR. Each subgroup had different mutation patterns. PMF patients had a higher average number of additional gene mutations, especially a higher frequency of ASXL1 mutation; PLT and HGB levels were lower in ASXL1 mutation PMF patients.

[Value of dynamic MRI in monitoring the microenvironmental changes of anti-vascular therapy in a xenograft model]

Objective: To explore the feasibility of dynamic-enhanced magnetic resonance imaging (DCE-MRI) and blood oxygen level-dependent MRI (BOLD-MRI) in assessing the hemodynamics and tumor aggressiveness during treatment. Methods: The colon cancer xenograft model was established in BALB/C nude mice with HCT116 cell line. Sixteen nude mice were randomly divided into treatment and control groups (aged 6 to 8 weeks, weighted 15 to 18 g, Certificate No. 11400700325797), which were treated with bevacizumab and saline by intraperitoneal injection on the 1st, 4th, 7th, 10th and 13th day. DCE-MRI and BOLD-MRI were performed before and on the 3th, 6th, 9th, 12th, and 15th day after treatment. The vascular maturity and microenvironment hypoxia were confirmed by pathology. Results: The tumor volume of treatment group was significantly smaller than that of control group after 15 days ((712±43) vs (1 051±112) mm(3),P<0.01).The measurements of K(trans) were (0.135±0.005),(0.147±0.006),(0.175±0.009),(0.161±0.006), (0.140±0.005),(0.116±0.008)/min (F=81.386, P<0.01); K(ep) were (0.788±0.030),(0.804±0.036),(0.983±0.059), (1.105±0.091),(0.840±0.047),(0.786±0.041)/min(F=45.901,P<0.01);Ve were (0.652±0.006), (0.559±0.026), (0.466±0.016), (0.286±0.027), (0.363±0.020), (0.246±0.033) (F=384.290, P<0.01) and R2* values were (24.813±0.961), (24.675±1.070), (21.425±1.371), (17.850±0.885), (24.613±0.640), (27.013±0.734)/s (F=89.323, P<0.01) showed different trends with time in the treatment group, and the differences were statistically significant. The K(trans) values and tumor vessel maturity index (VMI) were higher than baseline values during 3-12 d after treatment. CD31 positive staining rate and VMI had the strongest correlations with K(trans) values (r=0.854 and 0.795), followed by AUC(180) (r=0.750 and 0.808), Ve (r=0.744 and 0.712) and K(ep) values (r=0.729 and 0.758), all P<0.05. R2* value positively correlated with the positive staining rate of HIF-1α and fibronectin (r=0.810 and 0.816), all P<0.05. Conclusion: DCE-MRI and BOLD-MRI are adequate to observe the tumor perfusion and hypoxia during anti-vascular treatment, and the R2* value can predict the tumor metastatic potential during the process of vascular normalization.

IRF1 Negatively Regulates Oncogenic KPNA2 Expression Under Growth Stimulation and Hypoxia in Lung Cancer Cells

Purpose

Karyopherin alpha 2 (KPNA2) has been reported as an oncogenic protein in numerous human cancers and is currently considered a potential therapeutic target. However, the transcriptional regulation and physiological conditions underlying KPNA2 expression remain unclear. The aim of the present study was to investigate the role and regulation of interferon regulatory factor-1 (IRF1) in modulating KPNA2 expression in lung adenocarcinoma (ADC).

Materials and methods

Bioinformatics tools and chromatin immunoprecipitation were used to analyze the transcription factor (TF) binding sites in the KPNA2 promoter region. We searched for a potential role of IRF1 in non-small-cell lung cancer (NSCLC) using Oncomine and Kaplan-Meier Plotter datasets. qRT-PCR was applied to examine the role of IRF1 and signaling involved in regulating KPNA2 transcription. Western blotting was used to determine the effects of extracellular stimulation and intracellular signaling on the modulation of KPNA2-related TF expression.

Results

IRF1 was identified as a novel TF that suppresses KPNA2 gene expression. We observed that IRF1 expression was lower in cancerous tissues than in normal lung tissues and that its low expression was correlated with poor prognosis in NSCLC. Notably, both ataxia telangiectasia mutated (ATM) and mechanistic target of rapamycin (mTOR) inhibitors reduced KPNA2 expression, which was accompanied by increased expression of IRF1 but decreased expression of E2F1, a TF that promotes KPNA2 expression in lung ADC cells. IRF1 knockdown restored the reduced levels of KPNA2 in ATM inhibitor-treated cells. We further demonstrated that epidermal growth factor (EGF)-activated mTOR and hypoxia-induced ATM suppressed IRF1 expression but promoted E2F1 expression, which in turn upregulated KPNA2 expression in lung ADC cells.

Conclusion

IRF1 acts as a potential tumor suppressor in NSCLC. EGF and hypoxia promote KPNA2 expression by simultaneously suppressing IRF1 expression and enhancing E2F1 expression in lung ADC cells. Our study provides new insights into targeted therapy for lung cancer.

[Clinical analysis of adult Philadelphia chromosome-positive acute lymphoblastic leukemia with p16 gene deletion]

目的

探讨p16基因缺失在成人Ph染色体阳性急性淋巴细胞白血病（Ph⁺ ALL）中的临床意义。

方法

回顾性分析80例Ph⁺ALL伴p16基因缺失患者的临床特征、免疫表型、细胞遗传学、分子生物学改变及其预后。

结果

31.3% Ph⁺ALL患者合并p16基因缺失；p16基因缺失组与非缺失组相比，初诊时高白细胞计数（WBC≥30×10⁹/L）更常见，高表达CD20，更易出现附加染色体异常，其中以累及7、8、19号染色体以及der（22）较为常见；两组诱导缓解率比较差异无统计学意义（P=0.033），p16基因缺失组患者治疗3个疗程后获BCR-ABL融合基因主要分子学反应（MMR）率和完全分子学反应（CMR）率均明显低于非缺失组（P值分别为0.034和0.036），且复发率明显高于非缺失组（P=0.033）；p16基因缺失组使用伊马替尼联合化疗者和使用达沙替尼联合化疗者的MMR、CMR率及复发率差异均无统计学意义（P值均>0.05）；p16基因缺失组患者3年总体生存（OS）率及无病生存（DFS）率分别为37.1%和12.4%，显著低于非缺失组的54.1%和45.9%（P值分别为0.037和0.026）；25例p16基因缺失患者中14例行异基因造血干细胞移植（allo-HSCT），其中位OS时间为21个月，明显长于非移植组患者的12个月（P=0.030）。

结论

成人Ph⁺ALL伴p16基因缺失患者预后相对较差，二代酪氨酸激酶抑制剂不能明显改善其疗效，但allo-HSCT能够改善部分患者的生存，明确p16基因缺失状态对于评估预后和指导临床治疗有重要意义。

[Clinical significance of cytogenetic monitoring in chronic myeloid leukemia]

Objective: To analyze the association of cytogenetic abnormalities with the prognosis of chronic myeloid leukemia (CML) patients in tyrosine kinase inhibitors (TKI) era. Methods: Karyotype analysis of chromosome G-banding was carried out in 387 newly diagnosed CML patients by short-term culture of bone marrow cells. The correlation of cytogenetic abnormalities and CML progression was explored in combination with ABL tyrosine point mutations. Result: Of 387 patients with positive BCR-ABL fusion gene assayed by fluorescence in situ hybridization (FISH) technique, 94.1% (364/387) patients were Ph positive and 5.9% (23/387) Ph negative; 320 patients (87.9%) had a translocation t (9;22) (q34;q11) and 5 (1.4%) a variant translocation t (v;22) . Additional cytogenetic aberrations (ACA) at diagnosis were found in 10.7% (39/387) Ph(+) patients, major route ACA in 22 (56.4%) cases and minor route ACA in 15 (38.5%) cases and 2 patients (5.1%) lacked the Y chromosome (-Y) ; 23.4% (71/303) patients occurred ACA during TKI treatment and the most frequent abnormalities were abnormal chromosome numbersd, which were likely associated with high proportion of disease progression (χ(2)=168.21, P<0.001) and ABL tyrosine point mutations (χ(2)=29.04, P<0.001) . Newly diagnosed CML-CP patients with t (9;22) (q34;q11) had a longer event-free survival (EFS) and disease-free survival (DFS) rates than that of patients with ACA (P=0.037; P=0.003) , while the overall survival (OS) had no significant differences (P=0.209) . As for CML-CP patients that occurred ACA during TKI therapy would have a marked low OS, EFS and DFS (all P<0.001) compared with no ACA occurred patients. Survival of advanced patients that occurred ACA were dramatically reduced. Conclusion: ACA often emerged during the disease progress in CML patients, regular and timely detection of chromosomes karyotype and ABL tyrosine point mutations during TKI treatment was important for therapeutic evaluation, progress and prognosis of CML.

[Clinical characteristics and prognosis of 35 patients with therapy-related hematological neoplasms]

目的

探讨治疗相关血液肿瘤的临床特征及预后。

方法

采用细胞形态学、流式细胞术、间期荧光原位杂交技术（I-FISH）、染色体核型分析对35例治疗相关血液肿瘤患者进行诊断和分型并回顾性分析其临床特征及预后。

结果

35例患者中，治疗相关急性髓系白血病（t-AML）20例，治疗相关急性淋巴细胞白血病（t-ALL）4例，治疗相关急性混合细胞白血病1例，治疗相关非霍奇金淋巴瘤（t-NHL) 8例，治疗相关骨髓增生异常综合征（t-MDS）2例。第一肿瘤至治疗相关恶性血液肿瘤的中位发病间隔期为29(16~90）个月，中位生存时间14(1~60）个月，3年累积生存率为17.1%。在25例治疗相关性急性白血病患者中，40.0%（10/25）合并复杂核型，36.0%（9/25）合并MLL断裂基因重排，12.0%（3/25）合并AML-ETO融合基因阳性，1例合并NPM1点突变，1例合并P16基因缺失。

结论

治疗相关血液肿瘤患者的预后差。

[An experimental study of mesenchymal stem cells in tissue engineering scaffolds implanted in rabbit corneal lamellae to increase keratoprosthesis biointegration]

OBJECTIVE

To complete a preliminary evaluation of the feasibility of implanting the complex of mouse bone marrow mesenchymal stem cells (BMSC) and a tissue engineering scaffold into rabbit corneal lamellae, based on which a solution may be proposed to consolidate the keratoprosthesis and the recipient surface, and to reduce the risk of complications.

METHODS

This experimental study was composed of two parts. (1) In vitro: some mouse BMSC were marked with red fluorescent proteins (RFP) and integrated with a decellularized pig articular cartilage extracellular matrix (ECM) scaffold. The cell survival was observed under a fluorescence microscope at 4 and 8 weeks. The cell distribution was examined by toluidine blue staining. The pore structure and the cell adhesion were observed under a scanning electron microscope. (2) in vivo: the complex of mouse BMSC and a decellularized scaffold was implanted into the lamellar cornea of 8 rabbit eyes with the fellow eyes as the controls. The eyes were sampled for observation using HE staining under a light microscope at 2, 4 and 8 weeks, respectively. The cell survival was examined under a fluorescence microscope, and the intracorneal cell survival at 8 weeks was observed using in vivo imaging. The conditions of ocular anterior segment of all the experimental animals were recorded.

RESULTS

(1) Under the scanning electron microscope, the ECM scaffolds showed satisfactory porosity required for the adhesion and growth of cells and tissues, and the cell distribution over the cell-scaffold complex can be observed by toluidine blue staining. (2) Under the immunofluorescence microscope, cell proliferation was observed in vitro and in the interlamellar space (the maximum observation time was 8 weeks) after the RFP-marked mouse BMSC were integrated in vitro with ECM scaffolds. (3) Under the light microscope (HE staining), the stromal cells were detected to increase at each timepoint. A small number of monocytes and some mouse BMSC were observed in the superficial layer of corneal stroma, with sparsely and orderly arranged collagenous fibers and no neovascularization. All the epithelial cells appeared as mononuclear, columnar and undamaged, and the shape of ECM scaffolds, which were fused with the collagens, became unclear. (4) By in vivo imaging, it was found that the mouse BMSC survived for 8 weeks after being integrated with scaffolds and implanted into the interlamellar space of rabbit cornea. (5) After the implantation of cell-scaffold complex, severe postoperative inflammatory reactions, obvious conjunctival congestion and neovascularization were not observed. The corneal tissues surrounding the recipient area were transparent. One week later, mild inflammatory reactions were barely observed, and the cornea was transparent enough to observe the scaffold in the stromal layers. Four weeks later, the scaffolds became thinner. Eight weeks later, the scaffolds became extremely thin with normal vascular system in the corneal limbus.

CONCLUSIONS

The ECM scaffold is a solid and biocompatible carrier for the growth and proliferation of BMSC. The mouse BMSC can grow and proliferate in the microenvironment of the interlamellar space of cornea.

Effects of conjugated linoleic acid on the expression levels of miR-27 and miR-143 in pig adipose tissue

In this study, we evaluated the effect and possible mech-anism of action of dietary conjugated linoleic acid (CLA) on pig body fat deposition. Landrace piglets (N = 48) were randomly divided into three groups, which were fed diets containing 0% (control), 1%, or 2% CLA. Dorsal and abdominal subcutaneous adipose tissues were col-lected, and real-time polymerase chain reaction (PCR) was used to de-termine the expression of adipocyte differentiation marker genes and associated microRNAs (miRNAs). Our results indicated that dietary CLA significantly decreased body fat deposition in the pig dorsum. The expression of adipocyte differentiation marker genes, including peroxi-some proliferator-activated receptor (PPAR)-γ and CCAAT/enhancer-binding protein α (C/EBPα) were not affected, whereas the expression of fatty acid binding protein 4 (FABP4) was significantly enhanced (P < 0.05). The expression of miR-27 and miR-143 in adipose tissue was significantly decreased. Data analysis indicated a significant negative correlation between miR-27 and FABP4 expression in the dorsal sub-cutaneous adipose tissue. In addition, the expression of miR-143 and miR-27 exhibited a significant negative relationship with FABP4 and PPARγ in the abdominal subcutaneous adipose tissue. Thus, miRNA levels in adipose tissues could be modulated by CLA, thereby affecting adipose metabolism.

Expression and clinical significance of miR-122 and miR-29 in hepatitis B virus-related liver disease

MicroRNA molecules have been increasingly regarded as a diagnostic and prognostic marker of certain diseases. The aim of this study was to investigate the expression and clinical significance of miR-122 and miR-29 in liver disease related to hepatitis B virus infection. The serum levels of miR-122 and miR-29 in 20 patients with hepatocellular carcinoma (HCC), 20 patients with liver cirrhosis (LC), 29 patients with chronic hepatitis B (CHB), 20 cases of hepatitis B virus carriers (ASC), and 20 healthy controls (HC) were determined by a fluorescence real-time quantitative PCR method and then evaluated by clinical correlation analysis. Compared with the serum levels of miR-122 in the HC, LC, and ASC groups, those in patients with HCC and CHB were significantly increased. The serum levels of miR-29 in LC patients were lower than those in the healthy controls (P < 0.01). A positive correlation was observed between the expression of miR-122 and miR-29, and HBV DNA in patients with CHB. A negative correlation was found between miR-29 and α-fetoprotein in patients with HCC. The elevation in miR-122 was correlated with liver damage in CHB patients and with the pathogenesis of liver cancer in HCC patients. The decrease in miR-29 expression was related to the incidence of liver fibrosis. The detection of miR-122 and miR-29 may be useful in evaluating the inflammatory liver injury and fibrosis associated with chronic HBV infection.

Molecular characterization of the receptor binding structure-activity relationships of influenza B virus hemagglutinin

Selectivity of α2,6-linked human-like receptors by B hemagglutinin (HA) is yet to be fully understood. This study integrates binding data with structure-recognition models to examine the impact of regional-specific sequence variations within the receptor-binding pocket on selectivity and structure activity relationships (SAR). The receptor-binding selectivity of influenza B HAs corresponding to either B/Victoria/2/1987 or the B/Yamagata/16/88 lineages was examined using surface plasmon resonance, solid-phase ELISA and gel-capture assays. Our SAR data showed that the presence of asialyl sugar units is the main determinant of receptor preference of α2,6 versus α2,3 receptor binding. Changes to the type of sialyl-glycan linkage present on receptors exhibit only a minor effect upon binding affinity. Homology-based structural models revealed that structural properties within the HA pocket, such as a glyco-conjugate at Asn194 on the 190-helix, sterically interfere with binding to avian receptor analogs by blocking the exit path of the asialyl sugars. Similarly, naturally occurring substitutions in the C-terminal region of the 190-helix and near the N-terminal end of the 140-loop narrows the horizontal borders of the binding pocket, which restricts access of the avian receptor analog LSTa. This study helps bridge the gap between ligand structure and receptor recognition for influenza B HA; and provides a consensus SAR model for the binding of human and avian receptor analogs to influenza B HA.

Versatile computer-controlled system for characterization of gas sensing materials

Design of a system used for characterizing gas sensing materials is described. It is distinctive of being able to measure electrical and optical responses of a sample simultaneously, control a number of measurement parameters, perform fast exchange of gaseous environment, and be fully controlled automatically. These features make the system to be versatile in determining most concerned performance indexes of a gas sensing material (e.g., sensitivity, stability, selectivity, response/recovery times, etc.) as functions of various combinations of measurement conditions (e.g., gas concentrations, temperature, total pressure, content of interferants, photo assist, relative humidity, soaking time in a fixed gas concentration, and number of switching cycles in a dynamic test, etc.). Rationales of the designs associated with general gas sensing mechanics are discussed.

Establishment of a poisoned animal model of toxic encephalopathy induced by 1,2-dichloroethane

1,2-dichloroethane(1,2-DCE) is toxic, especially by inhalation due to its high vapour pressure. Inhalation of concentrated 1,2-DCE vapor can induce effects on the human nervous system, even encephalopathy. However, 1,2-DCE toxic encephalopathy has seldom been reported, and no adequate data were available to evaluate the encephalopathy of 1,2-DCE in experimental animals. The aim of the present study was to establish a toxic experimental animal model induced by 1,2-DCE. Dose effect and time effect of 1,2-DCE on the nervous system were detected. The rats were treated by 1,2-DCE at various concentrations of 0, 2.5, 5.0, 10.0 g/m3 for 6 h and treatment of rats at 10.0 g/m3 for 0, 3, 6, and 12 h. Morphology of brain tissue was observed by HE staining and TEM under light and electron microscope, besides water contents in the cortex and medulla of rats were analyzed. The results indicated that 1,2-DCE induced abnormal histopathology, and significantly higher water content were confirmed in the cerebral cortex of toxic animal model in a dose- and time-dependent manner. To declare that 1,2-DCE could induce toxic encephalopathy with a pathological feature of cerebral edema is very important for the medical rescue in urgent toxic accidents.

Estimation of water vapor content in near-infrared bands around 1 mum from MODIS data by using RM-NN

An algorithm based on the radiance transfer model (RM) and a dynamic learning neural network (NN) for estimating water vapor content from moderate resolution imaging spectrometer (MODIS) 1B data is developed in this paper. The MODTRAN4 is used to simulate the sun-surface-sensor process with different conditions. The dynamic learning neural network is used to estimate water vapor content. Analysis of the simulation data indicates that the mean and standard deviation of estimation error are under 0.06 gcm(-2 )and 0.08 gcm(-2). The comparison analysis indicates that the estimation result by RM-NN is comparable to that of a MODIS water vapor content product (MYD05_L2). Finally, validation with ground measurement data shows that RM-NN can be used to accurately estimate the water vapor content from MODIS 1B data, and the mean and standard deviation of the estimation error are about 0.12 gcm(-2 )and 0.18 gcm(-2).

An epidemiological survey of low back pain and axial spondyloarthritis in a Chinese Han population

OBJECTIVE

To investigate the prevalence of low back pain (LBP) and axial spondyloarthritis (SpA) in a Chinese Han population.

METHODS

A face-to-face investigation was performed in the Han population of Dalang Town, Yangshan County, Guangdong Province, China, using a questionnaire established in France in 1999. First the clinical features associated with SpA were investigated, then the human leucocyte antigen (HLA)-B27 and sacroiliac joint radiographic examinations were carried out. Finally, the diagnosis of SpA was determined by rheumatologists.

RESULTS

A total of 13 315 subjects participated in the study and 10 921 were aged >16 years; of these, 787 (7.21%) had LBP. There were 92 axial SpA patients (0.782% in subjects >16 years old and 11.96% in subjects with LBP). There were 29 (0.253%) cases of ankylosing spondylitis (AS), 60 (0.507%) undifferentiated axial SpA (USpA), and three (0.022%) psoriatic arthritis (PsA). Patients in the SpA groups had higher percentages in onset <40 years, insidious onset, morning stiffness, and affected for >3 months compared with those in other LBP groups. Simultaneous symptoms associated with spondylitis, such as buttock pain, heel pain, psoriasis, and SpA family history, were more commonly present. Of the axial SpA patients, 82.67% were HLA-B27 positive, clearly a greater percentage than those (11.65%) in other LBP groups.

CONCLUSIONS

The survey questionnaire for SpA in this study is useful for axial SpA screening in China. In southern China, the prevalence of LBP is 7.21%. The prevalence of axial SpA is 0.782%. USpA is the most common subtype of SpA, followed by AS.

Association of IL-1 gene complex members with ankylosing spondylitis in Chinese Han population

There are reports of IL-1 complex gene polymorphisms in ankylosing spondylitis (AS; MIM 106300), but the results have been inconsistent among populations. Moreover, few studies examine the association between IL-1 complex gene polymorphisms and clinical symptoms of AS patients. We investigated polymorphisms of IL-1 complex with AS in the Chinese Han population in this study. Chinese Han AS patients and ethnically matched healthy controls were genotyped for five single nucleotide polymorphisms (IL1beta+3953, beta-511, F10.3, RN.4, RN.6/1) and the IL1RN.VNTR of IL-1 gene cluster. Allele, Genotype and haplotype frequencies were compared between cases and controls by SHEsis software. The frequency of allele C of the marker IL1F10.3 was significantly increased in AS patients versus controls [p = 0.001, odds ratio (OR) = 1.54, 95% confidence interval (CI) = 1.19-1.20; p = 0.002, respectively]. Strong linkage disequilibrium was identified between IL1B-511, IL1B+3953 and RN4 in both patients and healthy controls (D' > 0.95). Haplotypes of pairs of these markers (6) were also significantly associated with AS. The strongest associations observed was between allele combination B-511-T/B+3953-C/F10.3-C/RN4-T/RN2VNTR-1/RN6.1-C and AS (p = 3.32 x 10(-5), OR = 4.41, 95% CI=2.1-9.3). Clinical manifestation showed week association between RN2VNTR A2 allele and risk of peripheral arthritis (OR = 0.2, 95% CI = 0.07-0.91). The IL-1 gene cluster is associated with AS in Chinese population. This finding provides strong statistical support for the previously observed relationship and indicates possible association between clinical manifestation and genetic factor.

Effects of age and strain on yolk sac utilization and leptin levels in newly hatched broilers

The dynamics of yolk sac utilization and changes of leptin levels in serum, hypothalamus, and yolk sac with age were investigated in Beijing-You (BY) and Arbor Acres (AA) male broilers during 11 d after hatch. The growth rate and feed intake of BY broilers were lower (P < 0.0001) than those of AA broilers, but the dynamics of the weights and total energy contents of yolk sacs were similar between both strains and decreased exponentially with age. Leptin levels in yolk sacs of both broiler strains increased with age during 3 d posthatching. Compared with those of AA broilers, leptin levels in yolk sacs of BY broilers were greater (P <or= 0.0413) on d 0 and 3. There was no change in serum leptin levels in BY broilers, whereas in AA broilers, serum leptin levels on d 1 and 3 were greater (P <or= 0.0306) than that on d 0 and then decreased with age. Compared with AA broilers, BY broilers showed lower (P <or= 0.0254) levels of serum leptin on d 1 and 3. Hypothalamic leptin levels of both strains decreased with age except AA broilers on d 0. Hypothalamic neuropeptide Y (NPY) levels of BY and AA broilers increased with age until d 7 and then decreased. There were no differences in hypothalamic leptin and NPY levels between both strains during 11 d after hatch. Correlation analysis showed that average daily feed intake had a negative correlation with serum and hypothalamic leptin and positive correlation with hypothalamic NPY. Our results indicated that the dynamics of yolk sac utilization were similar between BY and AA broilers and decreased exponentially with age. The developmental changes of leptin and NPY in serum and hypothalamus with age varied in parameter and strain, and both signal molecules might be involved in the early programming of feed intake in chickens, but the mechanisms need further studies.

Expression and distribution of S-100 protein, CD83 and apoptosis-related proteins (Fas, FasL and Bcl-2) in thyroid tissues of autoimmune thyroid diseases

Previous studies have shown that dendritic cells (DCs) and apoptosis-related proteins play a critical role in the pathogenesis of autoimmune thyroid diseases (ATD). This study was designed to investigate the expression and distribution of S-100 protein, CD83 and apoptosis-related proteins (Fas, FasL and Bcl-2) in the thyroid tissues of ATD and their role in ATD pathogenesis as determined by immunochemical staing techniques and other methods. Pathological tissues of 30 patients with Hashimoto's thyroiditis (HT), 30 patients with Graves' disease (GD) and 30 cases of thyroid follicular adenoma (TFA, as control) were used for this study. A higher expression of S-100 in HT (4.2+/-3.1%) and GD (3.9+/-2.8%) vs TFA (0.95+/-0.64%) (p<0.001). was observed as well as a higher expression of CD83 in HT (22.58+/-13.96% and GD (29.92+/-14.43%) vs TFA (5.19+/-8.08%) (p<0.001). HT thyrocytes adjacent to thyroid infiltrating lymphocytes (TILs) showed greater increases in the levels of Fas and FasL than did the GD thyrocytes while HT TILs exhibited lower expression of Fas and FasL than did the GD TILs. GD thyrocytes expressed increased levels of the antiapoptotic protein Bcl-2 as compared to the low levels detected in HT thyrocytes. An opposite pattern was observed in the TILs in GD (low expression of Bcl-2) and HT (high expression of Bcl-2). The findings suggest that the high expression of DC markers is related to the pathogenesis of HT and GD. Up-regulation of both the number and matured functions of DCs may lead to the presentation of more antigens to lymphocytes which are related to the development of autoimmune thyroid diseases. The regulation of Fas/FasL/Bcl-2 in GD favors apoptosis of infiltrating lymphocytes and thyrocyte survival. The regulation of Fas/FasL/Bcl-2 in HT may promote thyrocyte apoptosis leading to hypothyroidism.

High-throughput genomic and proteomic analysis using microarray technology

BACKGROUND

High-density microarrays are ideally suited for analyzing thousands of genes against a small number of samples. The next step in the discovery process is to take the resulting genes of interest and rapidly screen them against thousands of patient samples, tissues, or cell lines to further investigate their involvement in disease risk or the response to medication.

METHODS

We used a microarray technology platform for both single-nucleotide polymorphisms (SNPs) and protein expression. Each microarray contains up to 250 elements that can be customized for each application. Slides contained either a 16- or 96-microarray format (4000-24,000 elements per slide), allowing the corresponding number of samples to be rapidly processed in parallel.

RESULTS

Results for SNP genotyping and protein profiling agreed with results of restriction fragment length polymorphism (RFLP) analysis or ELISA, respectively. Genotyping analyses, using the microarray technology, on large sample sets over multiple polymorphisms in the NAT2 gene were in full agreement with traditional methodologies, such as sequencing and RFLP analysis. The multiplexed protein microarray had correlation coefficients of 0.82-0.99 (depending on analyte) compared with ELISAs.

CONCLUSIONS

The integrated microarray technology platform is adaptable and versatile, while offering the high-throughput capabilities needed for drug development and discovery applications.

[Determination of solanesol in the extracts of tobacco leaves by high performance liquid chromatography]

A method for the determination of solanesol in the extracts of tobacco leaves by high performance liquid chromatography has been developed. The column used was Shim-pack CLC-SIL(5 microns, 5 mm i.d. x 150 mm) and the UV detector was set at 215 nm. The eluent was a mixture of n-hexane and isopropyl alcohol (98:2, V/V). As the results showed, the linear range was 1 microgram-10 micrograms(r = 0.9997), the average recovery of solanesol was 98.1% and the relative standard deviation was 1.9%. This method is fast, accurate and reproducible.

Characterization of male and female wingbeat frequencies in the Anopheles quadrimaculatus complex in Mississippi

Classifying individual mosquitoes of the Anopheles quadrimaculatus species complex to species has always been time consuming and complex, involving genetic analysis and profiling. We characterized the wingbeat frequencies of the 3 species of the Anopheles quadrimaculatus complex (An. quadrimaculatus, An. smaragdinus, and An. maverlius) that occur in Mississippi to determine if this character could successfully distinguish between individuals of the 3 species. Wingbeats of females varied from 320 to 480 beats/sec, but no significant differences in wingbeat frequencies were found among females from 3 populations of the 3 species. Wingbeats of males were higher than those of females (500-770 beats/sec), and the mean wingbeat frequency of An. maverlius was significantly different from the means of An. quadrimaculatus and An. smaragdinus, although overlap occurred at the individual level. Such overlap precludes use of wingbeat frequencies as an identification mechanism, and indicates that, at least for the An. quadrimaculatus complex, wingbeat frequencies are not involved in mate recognition.

[A chemiluminescence flow sensor for vitamin B1]

AIM

To determine vitamin B1 in pharmaceutical preparations by chemiluminescence (CL) flow sensor.

METHODS

When 200 microL of Na3PO4 was passed through an anion exchange column, K3Fe(CN)6 was eluted from the resin and then mixed with the vitamin B1 stream containing NaOH to product CL, by the fast oxidation reaction between vitamin B1 and K3Fe(CN)6 in alkaline solution.

RESULTS

The CL emission intensity was correlated with the vitamin B1 concentration in the range 1.0 x 10(-5) to 1.0 x 10(-3) mol.L-1 and the detection limit was 8.0 x 10(-6) mol.L-1 (3 sigma). A complete analysis, including sampling and washing, can be performed within 2 min with a relative standard deviation of less than 4.0%.

CONCLUSION

The vitamin B1 flow sensor was stable for over 200 analyses and has been applied successfully to determination of vitamin B1 in pharmaceutical preparations.

[Culture of human nasal respiratory epithelial cells in serum free medium supplemented with hormones and growth factors and measurement of human nasal ciliary motility using videomicroscopy]

OBJECTIVE

To establish a culture model of human nasal respiratory epithelial cells and a method of measuring human nasal ciliary motility.

METHOD

The human nasal respiratory epithelial cells were detached with collagenase and cultured in serum free medium supplemented with hormones and growth factors, the ciliary beat frequency was measured by videomicroscopy.

RESULT

After inoculation, cells cultured with this method adhered in 24 hours, confluented in 6-8 days and lived for 16 days. During that time ciliary beating was active, both acidic and neutral mucoitin granules were rich in goblet cells and all chromosome of 23 pairs were normal, the ciliary beat frequency in 29 subjects' nasal mucosa was (411 +/- 24) beats/min (mean +/- s).

CONCLUSION

A culture model of human nasal respiratory epithelial cells in serum free medium supplemented with hormones and growth factors and a method of measuring human nasal ciliary motility was successfully established.

A novel multi-domain mucin-like glycoprotein of Cryptosporidium parvum mediates invasion

Cryptosporidium parvum is a protozoan parasite which produces self-limited disease in immunocompetent hosts and devastating, persistent diarrhea in immunocompromised individuals. There is no effective treatment for cryptosporidiosis and little is known about the basic biology of the organism. Cloning and sequence analysis of the gene encoding GP900, a previously identified > 900 kDa glycoprotein, predicts a mucin-like glycoprotein composed of distal cysteine-rich domains separated by polythreonine domains and a large membrane proximal N-glycosylated core region. A trinucleotide repeat composed predominantly of the triplet ACA encodes the threonine domains. GP900 is stored in micronemes prior to appearance on the surface of invasive forms. The concentration of native GP900 which inhibits 50% (IC50) of invasion in vitro is low picomolar; the IC50 for a recombinant cysteine rich-domain is low nanomolar. These observations indicate that GP900 is a parasite ligand for a host receptor involved in attachment/invasion and suggest that immunotherapy or chemotherapy directed against GP900 may be feasible.

Respiratory symptoms and pulmonary function among Chinese rice-granary workers

The authors conducted a cross-sectional study of 474 rice-granary workers and 235 non-granary worker controls in a rural area near Shanghai, the People's Republic of China. Responses to a respiratory-symptom questionnaire and pre- and post-shift spirometry were obtained for all subjects. Area sampling was performed for total and vertically elutriated (</= 15 micrometer) dust levels. Total dust levels were high, ranging from 6.6 mg/m(3) to 59.8 mg/m(3), with vertical elutriated dust concentrations ranging from 2.0 to 10. 4 mg/m(3). The granary workers reported significantly more respiratory symptoms, including chronic cough, sputum production, chronic bronchitis, grain fever (ODTS), and nasal and skin irritation. Grain dust and tobacco smoking were more than additive for the prevalence of chronic cough and chronic bronchitis. After adjusting for confounders, the granary workers had lower mean FEV&inf1;/FVC values both pre- and post-shift, indicating an association between chronic grain-dust exposure and chronic airway obstruction. The results suggest that exposure to rice dust can induce pulmonary responses similar to those observed with exposures to other types of grains.

Structure, expression, and chromosomal localization of the type I human vasoactive intestinal peptide receptor gene

Vasoactive intestinal peptide (VIP) and other members of the pituitary adenylyl cyclase-activating peptide (PACAP) and secretin neuroendocrine peptide family are recognized with specificity by related G protein-coupled receptors. We report here the cloning, characterization, and chromosomal location of the gene encoding the human type I VIP receptor (HVR1), also termed the type II PACAP receptor. The gene spans approximately 22 kb and is composed of 13 exons ranging from 42 to 1400 bp and 12 introns ranging from 0.3 to 6.1 kb. Primer extension analysis with poly(A)+ RNA from human HT29 colonic adenocarcinoma cells indicated that the transcription initiation site is located at position -110 upstream of the first nucleotide (+1) of the translation start codon, and 75 nt downstream of a consensus CCAAT-box motif. The G+C-rich 5' flanking region contains potential binding sites for several nuclear factors, including Sp1, AP2, ATF, interferon regulatory factor 1, NF-IL6, acute-phase response factor, and NF-kappa B. The HVR1 gene is expressed selectively in human tissues with a relative prevalence of lung > prostate > peripheral blood leukocytes, liver, brain, small intestine > colon, heart, spleen > placenta, kidney, thymus, testis. Fluorescence in situ hybridization localized the HVR1 gene to the short arm of human chromosome 3 (3p22), in a region associated with small-cell lung cancer.

Mechanisms of cell transformation in the embryonic heart

The process of cell transformation in the heart is a complex one. By use of the invasion bioassay, we have been able to identify several critical components of the cell transformation process in the heart. TGF beta 3 can be visualized as a switch in the environment that contributes to the initial process of cell transformation. Our data show that it is a critical switch in the transformation process. Even so, it is apparently only one of the factors involved. Others may include other TGF beta family members, the ES antigens described by Markwald and co-workers and additional unknown substances. Observing the sensitivity of the process to pertussis toxin, there is likely to be a G-protein-linked receptor involved, yet we have not identified a known ligand for this type of receptor. Clearly, there are several different signal transduction processes involved. The existence of multiple pathways is consistent with the idea that the target endothelial cells receive a variety of environmental imputs, the sum of which will produce cell transformation at the correct time and place. Adjacent endothelial cells of the ventricle that do not undergo cell transformation are apparently refractory to one or more of the stimuli. Figure 4 depicts a summary diagram of this invasion process with localization of most of the molecules mentioned in this narrative. As hypothesized here, elements of the transformation process may recapitulate aspects of gastrulation. Since some conservation of mechanism is expected in cells, it is not surprising that cells undergoing phenotypic change might reutilize mechanisms used previously to produce mesenchyme from the blastodisk. Though we have preliminary data to suggest this point, confirmation of the hypothesis by perturbation of genes such as brachyury, msx-1, etc. will be required to establish this point. The advantage of this hypothesis is that it provides, from the work of others in the area of gastrulation, a ready source of molecules and mechanisms that can be tested in the transforming heart. Whereas, perturbation of such mechanisms at gastrulation may be lethal to the embryo, such molecules and mechanisms may be responsible for the high incidence of birth defects in the heart.

Cloning and functional expression of a human neuroendocrine vasoactive intestinal peptide receptor

Vasoactive intestinal peptide (VIP) is a potent mediator of gastrointestinal, nervous, pulmonary, vascular and immune functions. A cDNA was obtained from human HT29 intestinal epithelial cells and found to encode a 457 amino acid, 52 kDa VIP receptor. Transfection of the cDNA into COS-7 cells and 293 cells resulted in expression of specific saturable binding of VIP with a Kd of 0.8 nM, and induction of increases in intracellular cAMP by VIP with an EC50 of 1 nM. The human VIP receptor is homologous to other G protein-coupled receptors of the secretin-parathyroid hormone receptor family. A 2.8 kb transcript was detected in human lung, HT29 cells and Raji B-lymphoblasts with weaker expression in human brain, heart, kidney, liver and placenta.

Evidence for the covalent binding of aflatoxin B1-dichloride to cytosine in DNA

In vitro studies of the effect of aflatoxin B1-dichloride (AFB1-Cl2) on the template function for RNA synthesis of several single- and double-stranded synthetic DNAs containing cytosine and/or hypoxanthine bases are reported. The results indicate: (i) AFB1-Cl2 strongly inhibits the template function of the single-stranded homopolymer polydC and has no effect on polydI, (ii) the inhibition is stronger when cytosine is in the double-stranded alternating copolymer poly[d(I-C)], and (iii) polydI directed RNA synthesis can be inhibited if it is in the double-stranded homopolymer polydI.polydC, although the template function of the polydC strand is still inhibited to a greater extent. The evidence that the selective inhibition of the DNA template function is a direct reflection of the binding specificities of AFB1-Cl2 is provided by the binding studies of [3H]AFB1-Cl2 to these DNAs. The binding of AFB1-Cl2 to polydC is substantiated by the dose-response template inhibition and by the dose-response template binding studies. Additionally, these results show that AFB1 per se has neither inhibitory nor binding activity. Auto radiography of [alpha-32P]GTP labeled RNAs suggests that the mechanism of inhibition of polydC template function by AFB1-Cl2 is mainly due to the inhibition of the elongation of RNA synthesis. Spectrum measurement of the products of enzyme digestion of the AFB1-Cl2 modified polydC reveals that the deoxycytidine fraction gives a typical cytosine absorption peak at 275 nm followed by a broad peak between 300 and 400 nm with a maximum at 390 nm. High performance liquid chromatography confirms the existence of a cytosine-AFB1 adduct which absorbs strongly in the regions between 250 and 400 nm with peaks identifiable at 260, 350 and 390 nm. These results strongly suggest that AFB1 in the activated form of AFB1-Cl2 is able to covalently bind to cytosine in DNA.

Applications of preparative high-performance liquid chromatography to the separation and purification of peptides and proteins

The basic differences between the problems encountered in the development of the analytical and preparative applications of high-performance liquid chromatography are analyzed and the principles of optimization of a preparative separation outlined. The application of these principles to the purification of peptides and proteins are discussed with emphasis on the specific problems raised by the separation of high-molecular-mass compounds. The relative advantages and inconveniences of displacement and overloaded elution are presented. The applications of the various retention modes of liquid chromatography (ion exchange, reversed-phase adsorption, hydrophobic interactions, size exclusion and bioaffinity) to the separation of various peptide and protein mixtures and/or to the extraction and purification of some of these compounds are reviewed. Separation performance reported in the literature are summarized in table form.

An electroneurographic assessment of subclinical lead neurotoxicity

While heavy exposure to inorganic lead is capable of inducing symptomatic neuropathy in man, the subclinical neuropathy due to low levels of occupational lead exposure remains to be proved. The reported results of electroneurographic studies on lead workers, however, have been controversial. In this study, 40 lead smeltery workers and 50 non-exposed referents were investigated. The air concentrations of lead at worksites were 0.25 to 42.5 mg/m3. The geometric means of PbB, PbU and delta-ALAU in lead exposed group were 40.03 micrograms/dl, 71 micrograms/l and 4.68 mg/l respectively, which were significantly higher (P less than 0.001) than those (7.01 micrograms/dl, 6.0 micrograms/l and 1.81 mg/l respectively) in the reference group. There were no clinical symptoms or signs of nerve damage in either group. Alcoholism and diabetes were excluded in both groups. Nerve conduction velocity was measured by a DISA 1500 electromyograph in both groups. Eleven electroneurographic parameters, including motor nerve conduction velocity (MCV) and distal latency (DML) of median, ulnar and peroneal nerves as well as sensory nerve conduction velocity (SCV) and distal latency (DSL) of median, ulnar and sural nerves, showed statistically significant differences between the two groups. However, the results of electroneurographic measurements of each individual in the lead-exposed group were all within the normal range. There was no correlation between the blood-lead levels and the neurophysiological measurements except for the median MCV. No correlation was seen between the median MCV and the exposure duration.(ABSTRACT TRUNCATED AT 250 WORDS)

Adsorption isotherms on high-performance liquid chromatographic sorbents. I. Peptides and nucleic acid constituents on octadecyl-silica

A miniaturized chromatographic system with short, narrow-bone columns was used for the measurement of adsorption isotherms of peptides and of nucleic acid constituents on octadecyl-silica by frontal chromatography. The range of mobile phase composition was similar to that used in elution chromatography of the substances investigated. Adsorption isotherms were measured under different experimental conditions as far as the mobile phase pH and composition as well as the column temperature are concerned. Most isotherms were concave down, and the data were fitted to both the Langmuir and Jovanović models, the former yielding a somewhat better fit. Under certain conditions, sigmoidal isotherms were also observed and this behavior was attributed to solvent-mediated conformational changes and molecular stacking. The results shed light on the adsorption behavior of the substances under investigation on octadecyl-silica, the most commonly employed sorbent in reversed-phase chromatography, over a wide range of concentrations. This is of interest in preparative and process-scale chromatography.

Adsorption isotherms on high-performance liquid chromatographic sorbents. II. Proteins on cation exchangers with silica support

Adsorption isotherms of proteins were measured by frontal chromatography in a miniaturized chromatographic system with short, narrow-bore columns. The adsorbents were microparticulate, macroporous siliceous cation exchangers, used in the high-performance liquid chromatography of proteins, and the range of mobile phase compositions was similar to that used in elution chromatography for their separation. Adsorption of protein on the wetted stainless-steel parts of the system was reduced by coating the metal surface with a hydrophilic polymer layer. The adsorption isotherms of proteins were concave down and, in most cases, well represented by the Langmuir model. However, the data could also be fitted with reasonable accuracy to the isotherm equation by Jovanović. Although the siliceous cation exchangers were of different provenance, the isotherms of the proteins were similar. Isotherms measured by the shake-flask method were found to be identical with those obtained by frontal chromatography.

High-performance liquid chromatography of substituted p-benzoquinones and p-hydroquinones. II. Retention behavior, quantitative structure-retention relationships and octanol-water partition coefficients

The retention behavior of methoxy-substituted p-benzoquinones and the corresponding hydroquinones in reversed-phase chromatography was examined on octylsilica and two octadecylsilica stationary phases and with five hydroorganic mobile phases containing acetonitrile, methanol or tetrahydrofuran and additionally in most cases (NH3OH)3PO4 used as a reducing and buffering agent. The retention order of benzoquinones and hydroquinones was the same on each stationary phase with either methanol or acetonitrile as the organic modifier. On the other hand, minor differences in the retention order were observed with the various stationary phases. In all cases, satisfactory quantitative structure-retention relationships (QSRRs) were found and the data suggest that the differences in the retention behaviour of octadecylsilicas used in this study are silanophilic interactions which, together with solvophobic interaction contribute to the retention of these eluites. Further analysis showed that QSRRs of sterically crowded molecules must take into account reduced surface area available for binding. The retention data obtained with use of aqueous tetrahydrofuran as mobile phase failed to give rise to satisfactory QSRRs. This was attributed to selective solvation of eluite by tetrahydrofuran and/or nearly equipotent binding of eluite and tetrahydrofuran to stationary phase.

High-performance liquid chromatography of substituted p-benzoquinones and p-hydroquinones. I. Interplay of on-column redox reaction and the chromatographic retention process

Chromatograms exhibiting unusual elution profiles were obtained in the reversed-phase chromatography of methoxy-substituted hydroquinones with hydro-organic mobile phases. The dependence of the elution profiles on the flow-rate and the mass of injected sample indicated that peaks were caused by the interplay of the chromatographic retention process and the concomitant oxidation of hydroquinones in the chromatographic column. The reaction was first investigated in free solution and the first-order rate constants and equilibrium constants were estimated for the oxidation of 2-methoxy-, 2,5-dimethoxy-, 2,6-dimethoxy-, 2,3,5-trimethoxy- and 2,3,5,6-tetramethoxyhydroquinones. The effect of Fe3+ and Cu2+ on the oxidation of 2,6-dimethoxyhydroquinone was also examined and it was found that Fe3+ caused a ten-fold increase in the reaction rate. The oxidation of 2-methoxy- and 2,6-dimethoxyhydroquinones in the chromatographic column showed first-order and zerothorder kinetic behavior at low and high sample loads, respectively. Such change in reaction order is typical for heterogeneous reactions that follow Langmuir-Hinshelwood kinetics and suggests the existence of catalytically active sites on the silica. Upon purging the columns with EDTA, on-column oxidation of the hydroquinones was attenuated so that no reaction zones appeared on the chromatogram. Subsequent loading of the column with Fe3+, however, gave rise to broad reaction zones and possibly to total conversion of the hydroquinones to benzoquinones in the column. In all cases investigated the rate of oxidation was much higher in the column than in free solution. On the basis of the results obtained here, heavy mental-catalyzed reaction at the stationary phase surface is proposed to be the dominant mechanism for the oxidation reaction examined here.