[The value of quantitative flow ratio in the hemodynamic evaluation of myocardial bridge]

Objective: To explore the application value of quantitative flow ratio (QFR) in the hemodynamic evaluation of myocardial bridge and to preliminarily evaluate the correlation and related influencing factors between deformation quantitative flow ratio (D-QFR) and QFR. Methods: This is a cross-sectional study. Patients with CAG-confirmed simple myocardial bridge of the middle anterior descending coronary artery from June 2012 to June 2022 at the Air Force Medical Center were retrospectively included in this study. Systolic stenosis of mural coronary arteries (MCA) and myocardial bridge length were measured using quantitative coronary angiography. The patients were divided into mild stenosis group (<50% systolic stenosis) and moderate-to-severe stenosis group (≥50% systolic stenosis) according to the Nobel grading criteria. At different time periods (systolic and diastolic), the QFR values were measured at 3 locations (1 to 2 cm before the MCA entrance, the middle segment of the MCA, and 1 to 2 cm after the MCA exit), denoted as QFRa, QFRb, and QFRc, respectively, and the D-QFR values, incorporating vessel deformation information, were recorded. The MCA distal QFR≤0.8 in either stage was defined as an abnormal QFR value. QFR values were compared between the two groups at different locations and within each group. Factors associated with abnormal QFR values were analysed using multifactorial logistic regression. Spearman rank correlation analysis was used to examine the correlation between D-QFR values and systolic and diastolic QFR values.Multiple linear regression was used to analyse the factors associated with D-QFR. Results: A total of 83 patients were enrolled, including 58 males, aged (57.1±13.1) years. There were 48 cases in the mild stenosis group and 35 cases in the moderate-to-severe stenosis group, and the differences in systolic and diastolic QFRb and QFRc values between the two groups were statistically significant (all P<0.05). Within-group comparisons showed the values of QFRb and QFRc in the systolic phase were lower than those in the diastolic phase; QFRb and QFRc were both lower than QFRa during the same period (all P<0.05). Multifactorial logistic regression analysis showed that MCA systolic stenosis (OR=1.225, 95%CI 1.093-1.372, P<0.001) was an influential factor for abnormal QFR. D-QFR values were positively correlated with both systolic and diastolic QFR values (correlation coefficients were 0.849 and 0.675, respectively, both P<0.01). Multiple linear regression analysis showed that D-QFR values were negatively correlated with age (β=-0.208, P=0.029), systolic stenosis (β=-0.500, P<0.001), and myocardial bridge length (β=-0.211, P=0.036). Conclusions: The QFR values in middle and distal of myocardial bridge decrease. The systolic stenosis rate of myocardial bridge is an important factor affecting QFR value. D-QFR is positively correlated with both systolic and diastolic QFR values. Age, myocardial bridge systolic stenosis rate and length are factors influencing the D-QFR values.

[Advances in hepatitis E epidemiology]

Hepatitis E is a viral hepatitis that the hepatitis E virus (HEV) causes. In the early 1980s, the hepatitis E virus was first discovered and identified, and it is one of the important pathogens that cause acute viral hepatitis globally. HEV infection is usually self-limiting, but in some groups of populations, such as pregnant women, patients with chronic liver disease, and the elderly, the prognosis is poor and may result in acute or subacute liver failure or even death. In addition, HEV infection can occur in chronically immunocompromised populations. At present, some regions and countries are not paying enough attention to hepatitis E prevention, diagnosis, and treatment, which suggests that we should study the epidemiology of HEV infection.

Association of BMAL1 clock gene polymorphisms with fasting glucose in children

BACKGROUND

The brain and muscle Arnt-like protein-1 (BMAL1) gene is an important circadian clock gene and previous studies have found that certain polymorphisms are associated with type 2 diabetes in adults. However, it remains unknown if such polymorphisms can affect fasting glucose in children and if other factors modify the associations.

METHODS

A school-based cross-sectional study with 947 Chinese children was conducted. A multivariable linear regression model was used to analyze the association between BMAL1 gene polymorphisms and fasting glucose level.

RESULTS

After adjusting for age, sex, body mass index (BMI), physical activity, and unhealthy diet, GG genotype carriers of BMAL1 rs3789327 had higher fasting glucose than AA/GA genotype carriers (b = 0.101, SE = 0.050, P = 0.045). Adjusting for the same confounders, rs3816358 was shown to be significantly associated with fasting glucose (b = 0.060, SE = 0.028, P = 0.032). Furthermore, a significant interaction between rs3789327 and nutritional status on fasting glucose was identified (P_interaction = 0.009); rs3789327 was associated with fasting glucose in the overweight/obese subgroup (b = 0.353, SE = 0.126, P = 0.006), but not in non-overweight/non-obese children.

CONCLUSIONS

BMAL1 polymorphisms were significantly associated with the fasting glucose level in children. Additionally, the observed interaction between nutritional status and BMAL1 supports promoting an optimal BMI in children genetically predisposed to higher glucose level.

IMPACT

Polymorphisms in the essential circadian clock gene BMAL1 were associated with fasting blood glucose levels in children. Additionally, there was a significant interaction between nutritional status and BMAL1 affecting fasting glucose levels. BMAL1 rs3789327 was associated with fasting glucose only in overweight/obese children. This finding could bring novel insights into mechanisms by which nutritional status influences fasting glucose in children.

[The expression of clock gene CLOCK and its clinical significance in nasopharyngeal carcinoma]

Objective: To explore the relationship between expression levels of CLOCK mRNA and protein and the clinical characteristics of patients with nasopharyngeal carcinoma. Methods: The frozen tissue specimens from 33 patients with nasopharyngeal carcinoma in the Affiliated Tumor Hospital of Guizhou Medical University from 2018 to 2019 were collected. Seventeen cases of tissue specimens from patients with nasopharyngeal chronic inflammation in the Affiliated Hospital of Guizhou Medical University in 2019 were collected. From 2008 to 2014, 68 cases of formalin-fixed paraffin-embedding (FFPE) nasopharyngeal carcinoma tissue and 37 cases of FFPE nasopharyngeal chronic inflammation tissue were collected from the Affiliated Tumor Hospital of Guizhou Medical University. Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot (WB) were used to detect the mRNA and protein expression levels of CLOCK. The nasopharyngeal carcinoma cells including CNE1, CNE2, 5-8F and the normal nasopharyngeal epithelial cell NP69 were cultured. qRT-PCR was used to detect the expression level of CLOCK mRNA in each cell line at the time points of ZT2, ZT6, ZT10, ZT14, ZT18 and ZT22. The cosine method was used to fit the rhythm of CLOCK gene in nasopharyngeal carcinoma. The protein expression of CLOCK protein was detected by using immunohistochemical method in 68 cases of nasopharyngeal carcinoma and 37 cases of nasopharyngeal chronic inflammation tissue. Survival was analyzed by Kaplan-Meier method and Log rank test, and the influencing factors was analyzed by Cox regression model. Results: The expression levels of CLOCK mRNA in CNE1, CNE2 and 5-8F cells (0.63±0.07, 0.91±0.02 and 0.33±0.04, respectively) were lower than that in NP69 cell (1.00±0.00, P<0.05). The expression levels of CLOCK protein in CNE1, CNE2 and 5-8F cells (0.79±0.06, 0.57±0.05 and 0.74±0.10, respectively) were lower than that of NP69 cells (1.00±0.00, P<0.05). The expressions of CLOCK mRNA in nasopharyngeal carcinoma cells including CEN1, CNE2, 5-8F and normal nasopharyngeal epithelial cell NP69 were different at different time points, with temporal fluctuations. The fluctuation periods of CLOCK mRNA in CNE1, CNE2, 5-8F, and NP69 cells were 16, 14, 22 and 24 hours, respectively. The peak and trough times were ZT10: 40 and ZT18: 40, ZT10 and ZT3, ZT14: 30 and ZT3: 30, ZT12: 39 and ZT0: 39, respectively. CLOCK mRNA and protein expression levels in nasopharyngeal carcinoma tissues (0.37±0.20 and 0.20±0.26, respectively) were lower than those in nasopharyngeal chronic inflammation tissues (1.00±0.00 and 0.51±0.41, respectively, P<0.05). The 1, 3, and 5-year survival rates of patients in the CLOCK protein high expression group (CLOCK protein expression level ≥ 0.178) were 96.2%, 92.1%, and 80.1%, respectively, which were higher than those in the low expression group (CLOCK protein expression level <0.178, 92.9% , 78.6% and 57.1%, respectively, P=0.009). The 1, 3, and 5-year progression-free survival (PFS) rates of patients in the CLOCK protein high expression group were 96.2%, 87.8%, and 87.7%, respectively, which were higher than those in the low expression group (92.7%, 82.2%, and 70.8%, respectively, P=0.105). Compared with the low-expression group (100.0%, 96.9%, and 90.0%, respectively), the 1, 3, and 5-year recurrence-free survival rates of patients in the CLOCK protein high expression group (100.0%, 95.7%, and 95.7%, respectively) were not statistically significant (P=0.514). Compared with the low-expression group (92.7%, 82.2%, and 79.3%), the 1, 3, and 5-year survival rates without metastasis in the CLOCK protein high expression group (96.2%, 92.0%, and 92.0%, respectively) were not statistically significant (P=0.136). CLOCK protein expression and T stage were independent prognostic factors of overall survival (P<0.05). Conclusions: The expression of CLCOK is downregulated in the nasopharyngeal carcinoma cell and nasopharyngeal carcinoma tissues. Clock gene CLOCK is rhythmically expressed in the nasopharyngeal carcinoma cells and normal nasopharyngeal epithelial cells. Compared with normal nasopharyngeal epithelial cells, the fluctuation period of CLOCK in nasopharyngeal carcinoma cells is shortened. The overall survival of patients in the CLOCK protein high expression group is better than that of low expression group. The expression of CLOCK protein is an independent influencing factor for overall survival. CLOCK gene may be a potential tumor suppressor gene in the nasopharyngeal carcinoma.

[Long-term oxygen treatment in patients with chronic obstructive pulmonary disease]

This paper introduced several problems of long-term oxygen therapy in chronic obstructive pulmonary disease (COPD) patients, including basic concepts, research progress at home and abroad, physiological significance of long-term oxygen therapy, clinical indications, contraindications, long-term oxygen therapy under special conditions, oxygen source, connection mode, inhaled oxygen concentration management, airway humidification, cooperation and safety of non-invasive ventilation.

Association Between Eating Speed and Metabolic Syndrome: A Systematic Review and Meta-Analysis

Objective: This review aimed to systematically summarize and meta-analyze the association between eating speed and metabolic syndrome (MetS). Methods: Following the Preferred Reporting Items for Systematic Reviews, and Meta Analyses (PRISMA) guidelines, four electronic databases (PubMed, Web of Science, MEDLINE, and EMBASE) were searched until March 2021 to identify eligible articles based on a series of inclusion and exclusion criteria. Heterogeneity was examined using I ² statistics. Using random-effects models, the pooled odds ratios (ORs), and 95% CIs were calculated to evaluate the association between eating speed with MetS and its components, including central obesity, blood pressure (BP), high-density lipoprotein cholesterol (HDL), triglyceride (TG), and fasting plasma glucose (FPG). Results: Of the 8,500 original hits generated by the systematic search, 29 eligible studies with moderate-to-high quality were included, involving 465,155 subjects. The meta-analysis revealed that eating faster was significantly associated with higher risks of MetS (OR = 1.54, 95% CI: 1.27-1.86), central obesity (OR = 1.54, 95% CI: 1.37-1.73), elevated BP (OR = 1.26, 95% CI: 1.13-1.40), low HDL (OR = 1.23, 95% CI: 1.15-1.31), elevated TG (OR = 1.29, 95% CI: 1.18-1.42), and elevated FPG (OR = 1.16, 95% CI: 1.06-1.27) compared to eating slowly. Conclusions: The results of the review indicated that eating speed was significantly associated with MetS and its components. Interventions related to decreasing eating speed may be beneficial for the management of MetS. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021242213, identifier: CRD42021242213.

[Assessment of heart's changes of elite Chinese male weightlifter by speckle tracking echocardiography]

OBJECTIVE

To evaluate the changes of heart structure and function in elite Chinese weightlifters by spot tracking technique.

METHODS

Chinese elite male weightlifters (weightlifter group, n=16) and age-matched healthy men (control group, n=16) were included as subjects. Transthoracic echocardiography and speckle-tracking automatic functional imaging were used for two-dimensional myocardial strain measurements.

RESULTS

The thickness of septum and left ventricular (LV) posterior wall and the myocardial mass index of LV were all higher than those of the control group [(9.3±1.3) mm vs. (8.0±0.4) mm, (9.2±0.8) mm vs. (8.0±0.8) mm, (77.8±12.8) g/m² vs. (67.8±11.2) g/m², all P < 0.05]. Although the LV ejection fraction (LVEF) and global long axis strain value (LVGLS) were not significantly different from those in the control group, the LV mean Sm and Em reflecting the systolic and diastolic functions of the LV were lower than those in the control group (P < 0.05). Further myocardial strain analysis showed that the absolute value of the long axial strain of the basal anteroseptal and mid-inferoseptal segments of the weightlifters were significantly lower than those of the control group [|(-15.1±4.2)%|vs.|(-18.7±3.0)%|, |(-18.8±2.6)%|vs.|(-21.3±2.8)%|, all P < 0.05]. There was no significant difference in other segments. The athletes were divided into two groups according to their best performance in the National Youth Games. The athletes were divided into two sub-groups according to their performance in the National Youth Games. The thickness of the septum in the sub-group with better performance (who ranked the 1^st to 8^th) was larger [(10.2±1.1) mm vs. (8.5±1.0) mm, P < 0.05], and the absolute value of the long-axis strain in the mid-inferoseptal segment was lower [|(-17.1±2.1)%|vs.|(-20.4±2.1)%|, P < 0.05].

CONCLUSION

The thickening of septum is more obvious in the excellent weightlifters, accompanied by the decrease of myocardial systolic function. The speckle-tracking technique of echocardiography can identify the changes of the heart structure and function of elite athletes at an early stage, which may provide a basis for sports medicine supervision and the selection of excellent talents.

Prevalence of Hyperhomocysteinemia in China: An Updated Meta-Analysis

Simple Summary

Hyperhomocysteinemia has been defined as an elevated serum concentration of homocysteine exceeding 15 μmol/L and has been proven to play an important role in the pathogenesis of cerebrovascular disease. The prevalence of hyperhomocysteinemia in China has been outlined in a previous meta-analysis. Considering the key role of homocysteine in the process of vascular injury, more studies have been conducted to prevent hyperhomocysteinemia by nutritional supplements such as folic acid or other treatments. Additionally, studies have shown that the prevalence of hyperhomocysteinemia increases over time; therefore, it was necessary to provide an update from the previous meta-analysis on homocysteine status in China. This was needed to understand the prevalence, the trend in changes over time, and its determinants. The results highlight that the prevalence of hyperhomocysteinemia is increasing in China, especially among the elderly, men, and residents in the north, inland areas, and rural areas of China.

Abstract

We conducted a meta-analysis to systematically assess the prevalence of hyperhomocysteinemia (HHcy) in China, its change over time, and its determinants. Literature searches were conducted using English databases (PubMed, Embase, and Web of Science) and Chinese databases (CNKI, CBM, VIP, and Wanfang). The time ranges were from Jan 2014 to Mar 2021 in China. We adopted the random effects model to estimate the pooled positive rates of HHcy and corresponding 95% confidence intervals (95% CI). To find the sources of heterogeneity, we performed subgroup analysis and meta-regression. A total of 29 related articles were identified involving 338,660 participants with 128,147 HHcy cases. The estimated prevalence of HHcy in China was 37.2% (95% CI: 32.6–41.8%, I² = 99.8%, p for heterogeneity < 0.001). The trend of HHcy prevalence was gradually upward over time, with increases during 2015–2016 (comparison to 2013–2014, p < 0.001), but steady between 2015–2016 and 2017–2018. Subgroup analysis showed that the prevalence was higher in the elderly over 55 years old, males, and residents in the north, inland, and rural China (for each comparison, p < 0.001). Meta-regression analysis revealed that age and area of study contributed to 42.3% of the heterogeneity between studies. The current meta-analysis provides strong evidence that the prevalence of HHcy is increasing in China, and varies substantially across different ages, genders, and geographic distribution. Accordingly, high-risk population groups should be focused on, and public health policies and strategies should be carried out to prevent and control HHcy in China.

Phosphatase and tensin homolog (PTEN) suppresses triacylglycerol accumulation and monounsaturated fatty acid synthesis in goat mammary epithelial cells

Phosphatase and tensin homolog (PTEN) is a well-known tumor suppressor in nonruminants and regulates various cellular processes including growth through dephosphorylation of phosphoinositide substrates. Although studies with bovine mammary tissue suggested a role for PTEN during lactation, its potential role in lipid metabolism remains unknown. Objectives of the present study were to determine PTEN abundance in goat mammary tissue at 2 stages of lactation (n = 6 Xinong Saanen dairy goats per stage), and to use gene-silencing and adenoviral transfections in vitro with isolated goat mammary epithelial cells (GMEC) to evaluate the role of PTEN abundance of lipid metabolism-related genes. Abundance of PTEN decreased by 51.5% at peak lactation compared with the dry period. The PTEN was overexpressed in isolated GMEC through adenoviral transfection using an adenovirus system with Ad-GFP (recombinant adenovirus of green fluorescent protein) as control, and silenced via targeted small interfering RNA (siRNA) transfection with a scrambled small interfering RNA as a negative control. Cell culture was performed for 48 h before RNA extraction, triacylglycerol (TAG) analysis, and fatty acid analysis. Overexpression of PTEN downregulated abundance of acetyl-coenzyme A carboxylase α (ACACA), fatty acid synthase (FASN), sterol regulatory element binding transcription factor1 (SREBF1), stearoyl-coenzyme A desaturase 1 (SCD1), diacylglycerol acytransferase 1 (DGAT1), 1-acylglycerol-3-phosphate O-acyltransferase 6 (AGPAT6) coupled with an increase in patatin-like-phospholipase domain containing 2 (PNPLA2), hormone-sensitive lipase (LIPE), and carnitine palmitoyltransferase 1 β (CPT1B). Furthermore, overexpressing PTEN in vitro resulted in a significant decrease in TAG concentration and concentration of C16:1. In contrast, interference of PTEN led to an opposite effect on lipid metabolism in GMEC. These changes suggested a shift from lipogenesis and esterification to lipolysis and fatty acid oxidation. Collectively, PTEN seems to play a role in monounsaturated fatty acids synthesis and lipid accumulation in GMEC.

[Analysis on serotype and antimicrobial resistance of invasive non-typhoidal Salmonella]

Objective: To investigate the serotypes and antimicrobial resistance of seven invasive non-typhoidal Salmonella (iNTS) isolates. Methods: For 7 iNTS strains collected, serotype identification, antimicrobial susceptibility testing and whole genome sequencing were performed. We identified, annotated and analyzed the serotypes, MLST types, and antimicrobial resistance genes. Results: Among the 7 tested iNTS isolates, we found one Salmonella Typhimurium strain and two Salmonella Ⅰ 4, [5], 12: i:- strains whose MLST types were ST34, two Salmonella Enteritidis strains, one Salmonella Corvallis strain and one strain of unknown serotype with the antigenic formulae of Ⅰ 4, [5], 12: d:- (ST279 type). Six of seven strains were monophasic and the deletion or pseudogenization of Salmonella Flagellum gene might contribute to the enhancement of Salmonella invasiveness. None was found to be resistant to tigarcycline, aztreonam, amikacin, cephalosporins and carbapenem and one Salmonella Typhimurium strain was found to be co-resistant to eight classes of antimicrobials at the same time. Resistance genes were generally in accord with relative resistant phenotypes. Conclusion: The iNTS strains could show high level multi-drug resistance, indicating that close attention should be paid to the resistance of iNTS though the overall resistance might be relatively not high.

Steady Bell State Generation via Magnon-Photon Coupling

We show that parity-time (PT) symmetry can be spontaneously broken in the recently reported energy level attraction of magnons and cavity photons. In the PT-broken phase, the magnon and photon form a high-fidelity Bell state with maximum entanglement. This entanglement is steady and robust against the perturbation of the environment, which is in contrast to the general wisdom that expects instability of the hybridized state when the symmetry is broken. This anomaly is further understood by the compete of non-Hermitian evolution and particle number conservation of the hybrid system. As a comparison, neither PT-symmetry breaking nor steady magnon-photon entanglement is observed inside the normal level repulsion case. Our results may open an exciting window to utilize magnon-photon entanglement as a resource for quantum information science.

Quantifying the Mesoscopic Nature of Einstein-Podolsky-Rosen Nonlocality

Evidence for Bell's nonlocality is so far mainly restricted to microscopic systems, where the elements of reality that are negated predetermine results of measurements to within one spin unit. Any observed nonlocal effect (or lack of classical predetermination) is then limited to no more than the difference of a single photon or electron being detected or not (at a given detector). In this paper, we analyze experiments that report the Einstein-Podolsky-Rosen (EPR) steering form of nonlocality for mesoscopic photonic or Bose-Einstein condensate systems. Using an EPR steering parameter, we show how the EPR nonlocalities involved can be quantified for four-mode states, to give evidence of EPR-nonlocal effects corresponding to a two-mode number difference of 10^{5} photons, or of several tens of atoms (at a given site). Applying to experiments, we also show how the variance criterion of Duan, Giedke, Cirac and Zoller for EPR entanglement can be used to determine a lower bound on the number of particles in a pure two-mode EPR-entangled or steerable state.

A method for improving the accuracy of non-invasive prenatal screening by cell-free foetal DNA size selection

Background Non-invasive prenatal screening (NIPS) using cell-free foetal DNA (cfDNA) has been widely used for identifying common foetal aneuploidies (e.g. trisomy 21 (T21), trisomy (T18) and trisomy 13 (T13)) in clinical practice. The sensitivity and specificity of NIPS exceeds 99%, but the positive prediction value (PPV) is approximately 70% (combined T21, T18 and T13). Thus, some 30% of pregnant women who have positive NIPS results are eventually identified as normal by amniocentesis. These women therefore must undertake needless invasive tests and risk miscarrying healthy babies because of false positive NIPS results. Methods In order to achieve higher accuracy, we amended the standard NIPS (s-NIPS) protocol with an additional cfDNA size selecting step in agarose-electrophoresis. The advantage of the new method (named e-NIPS) was validated by comparing the results of e-NIPS and s-NIPS using 114 retrospective cases selected from 15,930 cases. Results Our results showed that the foetal cfDNA fraction can be enriched significantly by a size selection step. With this modification, all 98 negative cases and 9 of 11 false positive cases of s-NIPS were correctly identified by e-NIPS, resulting in an increased PPV from 71% to 77%. Additionally, a simulation test showed that e-NIPS is more reliable than s-NIPS, especially when the foetal cfDNA concentration and sequencing coverage are low. Conclusion cfDNA size selection is an important step in improving the accuracy of non-invasive prenatal screening for chromosomal abnormalities.

[Application of diffusion tensor imaging combined with virtual reality three-dimensional reconstruction in the operation of gliomas involved eloquent regions]

OBJECTIVE

To investigate the values of diffusion tensor imaging (DTI) and virtual reality (VR) techniques in design surgery program of gliomas near eloquent regions.

METHODS

In this study, 35 cases were retrospectively analyzed with gliomas involved language areas or rolandic regions operated in Department of Neurosurgery, Peking University Third Hospital from January 2015 to January 2019. Surgery programs were performed by Dextroscope virtual reality system. The pre-operative data, such as the magnetic resonance imaging (MRI), magnetic resonance arteriography (MRA) and DTI was transferred into the VR computer for restitution,Tumors, neural fiber tracts and blood vessels were reconstructed to simulate operation and design individual surgical plan. Neurological function was evaluated 1 week, 1 month and 3 months after operation.

RESULTS

Virtual reality three-dimensional images of the 35 cases were successfully achieved, including neural fiber tracts,blood vessels and the lesions. The displacement and destruction of fiber tracts, the anatomic relationship between tumor and important fiber bundle, artery and vein could be shown clearly. Surgical simulation and surgery program of VR of the 35 patients were successfully performed. The 3D images obtained from virtual reality near to the real surgery. Ten of the 35 cases were defined as rolandic regions tumors, 14 of the 35 cases were defined as language areas tumors and 11 of the 35 cases involved both language areas and rolandic regions. Complete resection of enhancing tumor (CRET) was achieved in 30 cases (85.7%), subtotal resection in 5 cases (14.3%), neurological function improved in 34 cases (97.1%) after operation,and 1 case had no improvement compared with that before(2.9%). Thirteen cases without neurological deficit pre-operation, showed transient neurological deficit ,which were recovered about 10 days post-operation, 12 of 22 cases with pre-operative neurologic deficit, improved one week postoperation, 9 of 22 cases with pre-operative neurologic deficit improved one month after operation, the rest 1 case was recurrent with glioblastoma with aggravated hemiplegia symptom after operation, who died of cerebral hernia 2 months later.

CONCLUSION

Dextroscope virtual reality system can clearly expose and quantify the 3D anatomic relationship of tumors, neural fiber tracts and blood vessels surrounding gliomas near eloquent regions, which is helpful to design the best individualized surgery program, to improve surgical effect.

[Study on unprotected anal intercourse behavior in HIV-positive men who have sex with men in the context of knowing their HIV infection status in Chengdu]

Objective: To identify related factors associated with unprotected anal intercourse (UAI) among HIV-positive men who have sex with men (MSM) in the context of knowing their HIV infection status. Methods: HIV positive MSM who known that they had been infected with HIV for more than 6 months and accepted follow up services were recruited by convenience sampling method in Chengdu 2015. Semi-structured questionnaire was used to collect their information, such as demographic characteristics, antiviral therapy and sexual behavior characteristics etc. Logistic regression model was used for univariate and multivariate analyses. Results: A total of 330 HIV- positive MSM were recruited, 201 eligible MSM were interviewed. The prevalence of UAI in recent six months was 18.41% (37/201). The results of multivariate logistic regression analysis revealed that the number of anal intercourse with male ≥3 in last month (OR=6.22, 95%CI: 1.88-20.56), low education level (OR=7.29, 95%CI: 1.36-39.16), married, divorced or widowed status (OR=4.65, 95%CI: 1.13-19.17), homosexual cohabitation (OR=3.32, 95%CI: 1.01-10.95) were the risk factors related with UAI among the HIV-positive MSM. Conclusion: Frequent homosexual anal intercourse, low education level, married, divorced or widowed status and homosexual cohabitation might be the risk factors related with UAI in HIV-positive MSM in Chengdu.

Prognostic significance of downregulated BMAL1 and upregulated Ki-67 proteins in nasopharyngeal carcinoma

This study assessed the prognostic value of BMAL1 and Ki-67 expression in patients with nasopharyngeal carcinoma. Level of BMAL1 mRNA was assessed in tissue specimens from 36 nasopharyngeal carcinomas and 20 nasopharyngeal chronic inflammations using quantitative reverse transcriptase-polymerase chain reaction. Expression of BMAL1 and Ki-67 proteins was analyzed immunohistochemically in 90 paired nasopharyngeal carcinoma and distant normal tissues. The Kaplan-Meier curves and the Log-rank test were used to calculate prognostic significance stratified by BMAL1 and Ki67 protein expression and the COX regression model was to analyze the multivariate prognosis. BMAL1 mRNA was significantly reduced in nasopharyngeal carcinoma (4.67 ± 0.27 versus 6.64 ± 0.51 in chronic inflammation tissues, p = 0.002). Level of BMAL1 mRNA was associated with tumor distant metastasis (3.37 ± 0.66 versus 5.04 ± 0.27 compared with non-metastasis, p = 0.011). Level of BMAL1 protein was also reduced in tumor tissues and BMAL1 expression was associated with better 1-, 3- and 5-year overall survival (OS) of cancer patients (92.6%, 69.2% and 62.3% versus 59.1%, 40.9% and 0% in patients with low BMAL1 expressed tumors; p = 0.000). BMAL1 expression and age were independent prognostic factors for OS (p = 0.032). Furthermore, Ki-67 expression was high in tumor versus normal tissues and associated with poor OS of cancer patients (p = 0.035). The Pearson correlation analysis showed that there was an inverse association between BMAL1 and Ki-67 protein expression (p = 0.021). This study demonstrated that lost BMAL1 and Ki-67 overexpression were associated with poor OS of nasopharyngeal carcinoma patients.

MicroRNA-377 suppresses initiation and progression of esophageal cancer by inhibiting CD133 and VEGF

Esophageal cancer is one of the most lethal cancers worldwide with poor survival and limited therapeutic options. The discovery of microRNAs created a new milestone in cancer research. miR-377 is located in chromosome region 14q32, which is frequently deleted in esophageal squamous cell carcinoma (ESCC), but the biological functions, clinical significance and therapeutic implication of miR-377 in ESCC are largely unknown. In this study, we found that miR-377 expression was significantly downregulated in tumor tissue and serum of patients with ESCC. Both tumor tissue and serum miR-377 expression levels were positively correlated with patient survival. Higher serum miR-377 expression was inversely associated with pathologic tumor stage, distant metastasis, residual tumor status and chemoradiotherapy resistance. The roles of miR-377 in suppressing tumor initiation and progression, and the underlying molecular mechanisms were investigated. Results of in vitro and in vivo experiments showed that miR-377 overexpression inhibited the initiation, growth and angiogenesis of ESCC tumors as well as metastatic colonization of ESCC cells, whereas silencing of miR-377 had opposite effects. Mechanistically, miR-377 regulated CD133 and VEGF by directly binding to their 3' untranslated region. Moreover, systemic delivery of formulated miR-377 mimic not only suppressed tumor growth in nude mice but also blocked tumor angiogenesis and metastasis of ESCC cells to the lungs without overt toxicity to mice. Collectively, our study established that miR-377 plays a functional and significant role in suppressing tumor initiation and progression, and may represent a promising non-invasive diagnostic and prognostic biomarker and therapeutic strategy for patients with ESCC.

Characterization of the liver X receptor-dependent regulatory mechanism of goat stearoyl-coenzyme A desaturase 1 gene by linoleic acid

Stearoyl-coenzyme A desaturase 1 (SCD1) is a key enzyme in the biosynthesis of palmitoleic and oleic acid. Although the transcriptional regulatory mechanism of SCD1 via polyunsaturated fatty acids (PUFA) has been extensively explored in nonruminants, the existence of such mechanism in ruminant mammary gland remains unknown. In this study, we used goat genomic DNA to clone and sequence a 1,713-bp fragment of the SCD1 5' flanking region. Deletion assays revealed a core region of the promoter located between -415 and -109 bp upstream of the transcription start site, and contained the highly conserved PUFA response region. An intact PUFA response region was required for the basal transcriptional activity of SCD1. Linoleic acid reduced endogenous expression of SCD1 and sterol regulatory element binding factor-1 (SREBF1) in goat mammary epithelial cells. Further analysis indicated that both the sterol response element (SRE) and the nuclear factor Y (NF-Y) binding site in the SCD1 promoter were responsible for the inhibition effect by linoleic acid, whereas the effect was abrogated once NF-Y was deleted. In addition, SRE and NF-Y were partly responsible for the transcriptional activation induced via the liver X receptor agonist T 4506585 (Sigma-Aldrich, St. Louis, MO). When goat mammary epithelial cells were cultured with linoleic acid, addition of T 4506585 markedly increased SCD1 transcription in controls, but had no effect on cells with a deleted SRE promoter. These results demonstrated that linoleic acid can regulate SCD1 expression at the transcriptional level through SRE and NF-Y in a liver X receptor-dependent fashion in the goat mammary gland.

Liver X receptor α promotes the synthesis of monounsaturated fatty acids in goat mammary epithelial cells via the control of stearoyl-coenzyme A desaturase 1 in an SREBP-1-dependent manner

Stearoyl-coenzyme A desaturase 1 (SCD1) is a pivotal enzyme in the biosynthesis of monounsaturated fatty acids (MUFA). It is tightly regulated by transcription factors that control lipogenesis. In nonruminants, liver X receptor α (LXRα) is a nuclear receptor and transcription factor that acts as a key sensor of cholesterol and lipid homeostasis. However, the mechanism whereby LXRα regulates the expression and transcriptional activity of SCD1 in ruminant mammary cells remains unknown. In this study with goat mammary epithelial cells (GMEC), the LXRα agonist T 4506585 (T09) markedly enhanced the mRNA expression of SCD1 and sterol regulatory element binding factor 1 (SREBF1). The concentrations of C16:1 and C18:1 and their desaturation indices also were increased by LXRα activation. However, knockdown of LXRα did not alter the mRNA expression of SCD1. Although SCD1 was repressed by SREBF1 knockdown, T09 significantly increased SCD1 expression. Further analysis revealed that the SCD1 promoter activity was activated by LXRα overexpression. The goat SCD1 promoter contains 2 LXR response elements (LXRE), 1 sterol response element (SRE), and 1 nuclear factor Y (NF-Y) binding site. Site-directed mutagenesis of LXRE1, LXRE2, or SRE alone did not eliminate the upregulation of SCD1 when LXRα was overexpressed. In contrast, when NF-Y alone or in combination with SRE was mutated simultaneously, the basal transcriptional activity of the SCD1 promoter was markedly decreased and did not respond to LXRα overexpression. Furthermore, when SREBF1 was knocked down, overexpression of LXRα did not affect the promoter activity of SCD1. Together, these data suggest that LXRα regulates the expression of SCD1 through increasing SREBP-1 abundance to promote interaction with SRE and NF-Y binding sites. The present study provides evidence that LXRα is involved in the synthesis of MUFA in the goat mammary gland through an indirect mechanism.

Thyroid hormone responsive (THRSP) promotes the synthesis of medium-chain fatty acids in goat mammary epithelial cells

In nonruminants, thyroid hormone responsive (THRSP) is a crucial protein for cellular de novo lipogenesis. However, the role of THRSP in regulating the synthesis of milk fatty acid composition in goat mammary gland remains unknown. In the present study, we compared gene expression of THRSP among different goat tissues. Results revealed that THRSP had the highest expression in subcutaneous fat, and expression was higher during lactation compared with the dry period. Overexpression of THRSP upregulated the expression of fatty acid synthase (FASN), stearoyl-coenzyme A desaturase 1 (SCD1), diacylglycerol acyltransferase 2 (DGAT2), and glycerol-3-phosphate acyltransferase (GPAM) in goat mammary epithelial cells. In contrast, overexpression of THRSP led to downregulation of thrombospondin receptor (CD36) and had no effect on the expression of acetyl-coenzyme A carboxylase α (ACACA) and sterol regulatory element binding transcription factor1 (SREBF1). In addition, overexpressing THRSP in vitro resulted in a significant increase in triacylglycerol (TAG) concentration and the concentrations of C12:0 and C14:0. Taken together, these results highlight an important role of THRSP in regulating lipogenesis in goat mammary epithelial cells.

Detection of genuine tripartite entanglement and steering in hybrid optomechanics

Multipartite quantum entanglement is a key resource for ensuring security in quantum network. We show that by using a unified parameter in terms of reduced noise variances one can determine different types of tripartite entanglement of a given state generated in a hybrid optomechanical system, where an atomic ensemble is located inside a single-mode cavity with a movable mirror, with different thresholds for each type. In particular, the special quantum states which allow both entanglement and steering genuinely shared among atom-light-mirror modes can be observed, even though there is no direct interaction between the mirror and the atomic ensemble. We further show the robustness against mechanical thermal noise and damping, the relaxation time of atomic ensemble, as well as the effect of gain factors involved in the criteria. Our analysis provides an experimentally achievable method to determine the type of tripartite quantum correlation in a way.

[Analysis of vertebrobasilar dolichoectasia based on computational fluid dynamics]

OBJECTIVE

To analyze the hemodynamic states of vertebrobasilar dolichoectasia based on computational fluid dynamics technique.

METHODS

The original DICOM format image data from a patient with vertebrobasilar dolichoectasia (VBD), were imported by the Mimics software directly,and the 3D Objects were constructed.The simulation of model was made with Ansys software, the hemodynamic parameters such as streamlines, wall shear stress (WSS) and wall pressure were described.

RESULTS

There was stable laminar flow in proximal basilar artery and was no blood flow mixed by bilateral vertebral artery.However, Spiral flows were appeared in distal tortuous basilar artery. The low WSS regions in the vertebrabasilar junction section and inferior segment of basilar artery were coincide with the high wall pressure regions.It could be speculated the initial growth regions might be located in the vertebrabasilar junction section and inferior segment of basilar artery.Local regions with low WSS and high wall pressure might be associated with the occurrence and development of VBD.

CONCLUSION

CFD numerical simulation maybe can provide a theoretical basis for the role of hemodynamic factors in occurrence and development of VBD.

Classifying directional Gaussian entanglement, Einstein-Podolsky-Rosen steering, and discord

Using Venn diagrams, we classify the different types of two-mode Gaussian continuous variable quantum correlation including directional entanglement and Einstein-Podolsky-Rosen (EPR) steering. We establish unified signatures for one- and two-way quantum steering, entanglement, and discord beyond entanglement in terms of an EPR-type variance. By focusing on Gaussian states, we link an optimized condition for entanglement based on an EPR variance to the Simon-Peres condition. This allows us to quantify the asymmetry of the Gaussian entanglement, and to relate the asymmetry to a directional quantum teleportation protocol where Alice and Bob possess asymmetrically noisy channels. Our analysis enables a determination of the type and direction of quantum correlation in a way that is easily measured in experiment. We also find that for symmetric states, when discord exceeds a certain threshold, the states are necessarily steerable.

Genuine multipartite Einstein-Podolsky-Rosen steering

We develop the concept of genuine N-partite Einstein-Podolsky-Rosen (EPR) steering. This nonlocality is the natural multipartite extension of the original EPR paradox. Useful properties emerge that are not guaranteed for genuine multipartite entangled states. In particular, there is a close link with the task of one-sided, device-independent quantum secret sharing. We derive inequalities to demonstrate multipartite EPR steering for Greenberger-Horne-Zeilinger and Gaussian continuous variable states in loophole-free scenarios.

Einstein-Podolsky-Rosen entanglement strategies in two-well Bose-Einstein condensates

Criteria suitable for measuring entanglement between two different potential wells in a Bose-Einstein condensation are evaluated. We show how to generate the required entanglement, utilizing either an adiabatic two-mode or a dynamic four-mode interaction strategy, with techniques that take advantage of s-wave scattering interactions to provide the nonlinear coupling. The dynamic entanglement method results in an entanglement signature with spatially separated detectors, as in the Einstein-Podolsky-Rosen paradox.

Dynamic hysteresis scaling of ferroelectric Pb(0.9)Ba(0.1)(Zr(0.52)Ti(0.48))O(3) thin films

We measure systematically the intrinsic scaling behavior of dynamic hysteresis for Pb(0.9)Ba(0.1)(Zr(0.52)Ti(0.48))O(3) (PBZT) ferroelectric thin films with Pt electrodes on Si substrates, utilizing the Sawyer-Tower technique. For the as-prepared thin films of similar thickness and microstructure, over the low frequency range, the scaling follows the power law [Formula: see text] under low E(0) and the power law [Formula: see text] under high E(0), where ⟨A⟩ is the hysteresis area, and f and E(0) are the frequency and amplitude of the external electric field. In the high- f range, the power law for low E(0) takes the form of [Formula: see text], while that for high E(0) takes the form of [Formula: see text]. It is identified that the dynamic behaviors at low frequency mainly come from the intrinsic domain reversal instead of others like the leakage current, while the depolarization field may influence the frequency exponents at high frequency. We study the temperature scaling of the hysteresis, indicating that the scaling under low E(0) is roughly consistent with the (Φ(2))(2) model. Finally, we argue that experimentally obtained power law scaling for Pb(Zr(0.52)Ti(0.48))O(3) thin films prepared under the given conditions may not be reliable due to the polarization fatigue effect.

Testing for multipartite quantum nonlocality using functional bell inequalities

We show that arbitrary functions of continuous variables, e.g., position and momentum, can be used to generate tests that distinguish quantum theory from local hidden variable theories. By optimizing these functions, we obtain more robust violations of local causality than obtained previously. We analytically calculate the optimal function and include the effect of nonideal detectors and noise, revealing that optimized functional inequalities are resistant to standard forms of decoherence. These inequalities could allow a loophole-free Bell test with efficient homodyne detection.

Proteomic and functional analyses reveal a dual molecular mechanism underlying arsenic-induced apoptosis in human multiple myeloma cells

Multiple myeloma (MM) is an incurable plasma cell malignancy with a terminal phase marked by increased proliferation and resistance to therapy. Arsenic trioxide (ATO), an antitumor agent with a multifaceted mechanism of action, displayed clinical activity in patients with late-stage multiple myeloma. However, the precise mechanism(s) of action of ATO has not been completely elucidated. In the present study, we used proteomics to analyze the ATO-induced protein alterations in MM cell line U266 and then investigated the molecular pathways responsible for the anticancer actions of ATO. Several clusters of proteins altered in expression in U266 cells upon ATO treatment were identified, including down-regulated signal transduction proteins and ubiquitin/proteasome members, and up-regulated immunity and defense proteins. Significantly regulated 14-3-3zeta and heat shock proteins (HSPs) were selected for further functional studies. Overexpression of 14-3-3zeta in MM cells attenuated ATO-induced cell death, whereas RNAi-based 14-3-3zeta knock-down or the inhibition of HSP90 enhanced tumor cell sensitivity to the ATO induction. These observations implicate 14-3-3zeta and HSP90 as potential molecular targets for drug intervention of multiple myeloma and thus improve our understanding on the mechanisms of antitumor activity of ATO.

Digital quantum memories with symmetric pulses

We propose a digital approach to quantum memories using a single-mode oscillator-cavity model, in which the coupling is shaped in time to provide the optimum interface to a time-symmetric input pulse. Our generic model is applicable to any linear storage medium ranging from a superconducting device to an atomic medium.

High-throughput analysis of rat liver plasma membrane proteome by a nonelectrophoretic in-gel tryptic digestion coupled with mass spectrometry identification

In-gel digestion is commonly used after proteins are resolved by polyacrylamide gel electrophoresis (SDS-PAGE, 2-DE). It can also be used on its own in conjunction with tandem mass spectrometry (MS/MS) for the direct analysis of complex proteins. Here, we describe a strategy combining isolation of purified plasma membrane, efficient digestion of plasma membrane proteins in polyacrylamide gel, and high-sensitivity analysis by advanced mass spectrometry to create a new rapid and high-throughput method. The plasma membrane protein mixture is directly incorporated into a polyacrylamide gel matrix, After formation of the gel, proteins in the gel section are digested with trypsin, and the resulting peptides are subjected to reversed-phase, high-performance liquid chromatography followed by electrospray ion-trap tandem mass analysis. Using this optimized strategy, we have identified 883 rat liver membrane proteins, of which 490 had a gene ontology (GO) annotation indicating a cellular component, and 294 (60%) of the latter were known integral membrane proteins or membrane proteins. In total, 333 proteins are predicted by the TMHMM 2.0 algorithm to have transmembrane domains (TMDs) and 52% (175 of 333) proteins to contain 2-16 TMDs. The identified membrane proteins provide a broad representation of the rat plasma membrane proteome with little bias evident due to protein p I and molecular weight (MW). Also, membrane proteins with a high GRAVY score (grand average hydrophobicity score) were identified, and basic and acidic membrane proteins were evenly represented. This study not only offered an efficient and powerful method in shotgun proteomics for the identification of proteins of complex plasma membrane samples but also allowed in-depth study of liver membrane proteomes, such as of rat models of liver-related disease. This work represents one of the most comprehensive proteomic analyses of the membrane subproteome of rat liver plasma membrane in general.

ATDB: a uni-database platform for animal toxins

Venomous animals possess an arsenal of toxins for predation and defense. These toxins have great diversity in function and structure as well as evolution and therefore are of value in both basic and applied research. Recently, toxinomics researches using cDNA library sequencing and proteomics profiling have revealed a large number of new toxins. Although several previous groups have attempted to manage these data, most of them are restricted to certain taxonomic groups and/or lack effective systems for data query and access. In addition, the description of the function and the classification of toxins is rather inconsistent resulting in a barrier against exchanging and comparing the data. Here, we report the ATDB database and website which contains more than 3235 animal toxins from UniProtKB/Swiss-Prot and TrEMBL and related toxin databases as well as published literature. A new ontology (Toxin Ontology) was constructed to standardize the toxin annotations, which includes 745 distinct terms within four term spaces. Furthermore, more than 8423 TO terms have been manually assigned to 2132 toxins by trained biologists. Queries to the database can be conducted via a user-friendly web interface at http://protchem.hunnu.edu.cn/toxin.

DEPD: a novel database for differentially expressed proteins

SUMMARY

The Differentially Expressed Protein Database was designed to store the output of comparative proteomics studies and provides a publicly available query and analysis platform for data mining. The database contains information about more than 3000 differentially expressed proteins (DEPs) manually extracted from the published literature, including relevant biological, experimental and methodological elements. Tools for visualization and functional analysis of DEPs are provided via a user-friendly webinterface.

AVAILABILITY

http://protchem.hunnu.edu.cn/depd/.

Function of GATA transcription factors in hydroxyurea-induced HEL cells

HEL cells, a human erythroleukemia cell line, mainly express the fetal (gamma) globin gene and trace amount of the embryonic (epsilon) globin gene, but not adult (beta) globin gene. Here we show that hydroxyurea (HU) can induce HEL cells to express adult (beta) globin gene and lead these cells to terminal differentiation. Results showed in Gel mobility shift assays that GATA factors could specifically bind to the regulatory elements of human beta-globin gene, including the proximal regulatory element (the beta-promoter) and the distal regulatory elements (the DNase I hypersensitive sites in the LCR, HS2-HS4 core sequences). However, the DNA binding patterns of GATA factors were quite different between HU-induced and uninduced HEL cells. Western-blot analysis of nuclear extracts from both the uninduced and HU-induced HEL cells revealed that the level of GATA-2 transcription factor decreased, whereas the level of GATA-1 transcription factor increased following the time of hydroxyurea induction. Furthermore, using RT-PCR analysis the expression of human beta-globin gene in HU-induced HEL cells could be blocked again when HEL cells were incubated in the presence of antisense oligonucleotides for hGATA-1, suggesting that the upregulation of hGATA-1 transcription factor might be critical for the expression of human beta-globin gene in HU-induced HEL cells.

Ligand variation in the transferrin family: the crystal structure of the H249Q mutant of the human transferrin N-lobe as a model for iron binding in insect transferrins

Proteins of the transferrin (Tf) family play a central role in iron homeostasis in vertebrates. In vertebrate Tfs, the four iron-binding ligands, 1 Asp, 2 Tyr, and 1 His, are invariant in both lobes of these bilobal proteins. In contrast, there are striking variations in the Tfs that have been characterized from insect species; in three of them, sequence changes in the C-lobe binding site render it nonfunctional, and in all of them the His ligand in the N-lobe site is changed to Gln. Surprisingly, mutagenesis of the histidine ligand, His249, to glutamine in the N-lobe half-molecule of human Tf (hTf/2N) shows that iron binding is destabilized and suggests that Gln249 does not bind to iron. We have determined the crystal structure of the H249Q mutant of hTf/2N and refined it at 1.85 A resolution (R = 0.221, R(free) = 0.246). The structure reveals that Gln249 does coordinate to iron, albeit with a lengthened Fe-Oepsilon1 bond of 2.34 A. In every other respect, the protein structure is unchanged from wild-type. Examination of insect Tf sequences shows that the K206.K296 dilysine pair, which aids iron release from the N-lobes of vertebrate Tfs, is not present in the insect proteins. We conclude that substitution of Gln for His does destabilize iron binding, but in the insect Tfs this is compensated by the loss of the dilysine interaction. The combination of a His ligand with the dilysine pair in vertebrate Tfs may have been a later evolutionary development that gives more sophisticated pH-mediated control of iron release from the N-lobe of transferrins.

Expression, purification, and characterization of recombinant nonglycosylated human serum transferrin containing a C-terminal hexahistidine tag

Attachment of a hexa-His tag is a common strategy in recombinant protein production. The use of such a tag greatly simplifies the purification of the protein from the complex mixture of other proteins in the media or cell extract. We describe the production of two recombinant nonglycosylated human serum transferrins (hTF-NG), containing a factor Xa cleavage site and a hexa-His tag at their carboxyl-terminal ends. One of the constructs comprises the entire coding region for hTF (residues 1-679), while the other lacks the final three carboxyl-terminal amino acids. After insertion of the His-tagged hTFs into the pNUT vector, transfection into baby hamster kidney (BHK) cells, and selection with methotrexate, the secreted recombinant proteins were isolated from the tissue culture medium. Average maximum expression levels of the His-tagged hTFs were about 40 mg/L compared to an average maximum of 50 mg/L for hTF-NG. The first step of purification involved an anion exchange column. The second step utilized a Poros metal chelate column preloaded with copper from which the His-tagged sample was eluted with a linear imidazole gradient. The His-tagged hTFs were characterized and compared to both recombinant hTF-NG and glycosylated hTF from human serum. The identity of each of the His-tagged hTFs constructs was verified by electrospray mass spectroscopy. In summary, the His-tagged hTF constructs simplify the purification of these metal-binding proteins with minimal effects on many of their physical properties. The His-tagged hTFs share many features common to hTF, including reversible iron binding, reactivity with a monoclonal antibody, and presence as a monomer in solution.

Selective activation of mitomycin A by thiols to form DNA cross-links and monoadducts: biochemical basis for the modulation of mitomycin cytotoxicity by the quinone redox potential

Mitomycin A (MA) but not mitomycin C (MC) cross-linked linearized (32)P-pBR322 DNA in the presence of dithiothreitol (DTT) or glutathione (GSH), as shown by a sensitive DNA cross-link assay. Incubation of calf-thymus DNA with MA and DTT or mercaptoethanol (MER) resulted in the formation of MA-DNA adducts, which were isolated from nuclease digests of the drug-DNA complexes by HPLC. The adducts were characterized by their UV absorption spectra, electrospray ionization mass spectrometry (ESIMS), and facile conversion from 7-methoxy- to 7-amino-substituted mitosene type adducts upon 10% NH(4)OH treatment, which were identical with known adducts of MC. Both DNA interstrand and intrastrand cross-link adducts, linking two deoxyguanosine residues at N(2), as well as several deoxyguanosine-N(2) monoadducts of MA, were identified. No DNA adducts were formed with MC under the same conditions. A specificity of DNA cross-link formation for the CpG sequence was observed using 12-mer synthetic oligodeoxyribonucleotides as substrates and as DNA sequence models, in analogy to the known CpG sequence specificity of MC-induced DNA cross-links. MA is known to be more cytotoxic by 2-3 orders of magnitude than MC, and this property correlates with redox potentials of MA (-0.19 V) and MA analogues that are higher than those of MC (-0.40 V) and its analogues. It is suggested that the biochemical basis for the higher cytotoxic potency of MA is MA's propensity to be reductively activated by cellular thiols while MC is resistant to thiol activation. This distinction is probably derived from the large difference between the quinone redox potentials of the two drugs.

[Clinical study on treatment of oviduct obstruction by integrative traditional Chinese and Western medicine]

OBJECTIVE

To find an effective and practical treatment of oviduct obstruction (OvO).

METHODS

One hundred and twenty OvO patients were randomly divided into three groups, the TCM-WM group, treated with integrative traditional Chinese and western medicine, the TCM group treated with Chinese herbal medicine alone and the WM group treated with western medicine alone. The therapeutic effect as well as the effect of treatment on serum C-reactive protein (CRP) and interleukin-1 beta (IL-1 beta) were observed.

RESULTS

After treatment, the fallopian tube patency rate was 86.7% and the pregnant rate 85.0% in the TCM-WM group, while in the TCM group was 66.7% and 63.3% respectively, and in the WM group 53.3% and 50.0% respectively. Comparison among the three groups showed that the effect in the TCM-WM group was significantly superior to that in the other two groups (P < 0.01). The levels of CRP and IL-1 beta were all lowered after 3 courses of treatment, and the effect was more evident in the TCM-WM group (P < 0.01).

CONCLUSION

TCM-WM treatment is a good and practical method in treating oviduct obstruction.

[Characterization of cell death induced by anticancer antibiotic lidamycin in human hepatoma BEL-7402 cells]

AIM

To study the features of cell death induced by the anticancer antibiotic lidamycin (LDM) in human hepatoma BEL-7402 cells.

METHODS

Chromatin condensation was observed by co-staining with fluorescent dyes, hoechst 33342 and propidium iodide. "G1 sub-peak" was detected by flow cytometry and DNA ladder was observed using agarose gel electrophoresis. The caspase-3, 6 activities were measured with kits specific for them.

RESULTS

Typical apoptotic chromatin condensations appeared when the BEL-7402 cells were treated with the conventional antitumor agent mitomycin C30 mumol.L-1 for 12 h. However, an abnormal type of chromatin condensation occurred when the cells were treated with LDM 1 mumol.L-1 for 6 h, which was characterized with keeping the completeness of nuclear membrane and not forming apoptotic bodies. The DNA ladder patterns were observed using agarose gel electrophoresis. The "G1 sub-peak" occurred only in the cells treated with LDM for 24 h, though chromatin condensation was earlier detected in treatment with LDM for 6 h. The caspase-3, 6 activities were increased about 5 and 4 folds, after the cells were treated with LDM 1 mumol.L-1 for 6 h, as did mitomycin C. The time of initiating chromatin condensation was earlier than that of the high peak activities of caspase-6.

CONCLUSION

The characterization of cell death induced by lidamycin in the human hepatoma BEL-7402 cells differs from typical apoptosis. The results make it helpful to explain the molecular mechanism of the highly potent cytotoxicities of lidamycin toward tumor cells.

Spectral and metal-binding properties of three single-point tryptophan mutants of the human transferrin N-lobe

Human serum transferrin N-lobe (hTF/2N) contains three conserved tryptophan residues, Trp(8), Trp(128) and Trp(264), located in three different environments. The present report addresses the different contributions of the three tryptophan residues to the UV-visible, fluorescence and NMR spectra of hTF/2N and the effect of the mutations at each tryptophan residue on the iron-binding properties of the protein. Trp(8) resides in a hydrophobic box containing a cluster of three phenylalanine side chains and is H bonded through the indole N to an adjacent water cluster lying between two beta-sheets containing Trp(8) and Lys(296) respectively. The fluorescence of Trp(8) may be quenched by the benzene rings. The apparent increase in the rate of iron release from the Trp(8)-->Tyr mutant could be due to the interference of the mutation with the H-bond linkage resulting in an effect on the second shell network. The partial quenching in the fluorescence of Trp(128) results from the nearby His(119) residue. Difference-fluorescence spectra reveal that any protein containing Trp(128) shows a blue shift upon binding metal ion, and the NMR signal of Trp(128) broadens out and disappears upon the binding of paramagnetic metals to the protein. These data imply that Trp(128) is a major fluorescent and NMR reporter group for metal binding, and possibly for cleft closure in hTF/2N. Trp(264) is located on the surface of the protein and does not connect to any functional residues. This explains the facts that Trp(264) is the major contributor to both the absorbance and fluorescence spectra, has a strong NMR signal and the mutation at Trp(264) has little effect on the iron-binding and release behaviours of the protein.

Crystal structures and iron release properties of mutants (K206A and K296A) that abolish the dilysine interaction in the N-lobe of human transferrin

Human transferrin (Tf) is responsible for the binding and transport of iron in the bloodstream of vertebrates. Delivery of this bound iron to cells occurs by a process of receptor-mediated endocytosis during which Tf releases its iron at the reduced endosomal pH of approximately 5.6. Iron release from Tf involves a large conformational change in which the two domains that enclose the binding site in each lobe move apart. We have examined the role of two lysines, Lys206 and Lys296, that form a hydrogen-bonded pair close to the N-lobe binding site of human Tf and have been proposed to form a pH-sensitive trigger for iron release. We report high-resolution crystal structures for the K206A and K296A mutants of the N-lobe half-molecule of Tf, hTf/2N, and quantitative iron release data on these mutants and the double mutant K206A/K296A. The refined crystal structures (for K206A, R = 19.6% and R(free) = 23.7%; for K296A, R= 21.2% and R(free) = 29.5%) reveal a highly conserved hydrogen bonding network in the dilysine pair region that appears to be maintained even when individual hydrogen bonding groups change. The iron release data show that the mutants retain iron to a pH 1 unit lower than the pH limit of wild type hTf/2N, and release iron much more slowly as a result of the loss of the dilysine interaction. Added chloride ions are shown to accelerate iron release close to the pH at which iron is naturally lost and the closed structure becomes destabilized, and to retard it at higher pH.

The chloride effect is related to anion binding in determining the rate of iron release from the human transferrin N-lobe

The major function of human transferrin is to deliver iron from the bloodstream to actively dividing cells. Upon iron release, the protein changes its conformation from 'closed' to 'open'. Extensive studies in vitro indicate that iron release from transferrin is very complex and involves many factors, including pH, the chelator used, an anion effect, temperature, receptor binding and intra-lobe interactions. Our earlier work [He, Mason and Woodworth (1997) Biochem. J. 328, 439-445] using the isolated transferrin N-lobe (recombinant N-lobe of human transferrin comprising residues 1-337; hTF/2N) has shown that anions and pH modulate iron release from hTF/2N in an interdependent manner: chloride retards iron release at neutral pH, but accelerates the reaction at acidic pH. The present study supports this idea and further details the nature of the dual effect of chloride: the anion effect on iron release is closely related to the strength of anion binding to the apoprotein. The negative effect seems to originate from competition between chloride and the chelator for an anion-binding site(s) near the metal centre. With decreasing pH, the strength of anion binding to hTF/2N increases linearly, decreasing the contribution of competition with the chelator. In the meantime, the 'open' or 'loose' conformation of hTF/2N, induced by the protonation of critical residues such as the Lys-206/Lys-296 pair at low pH, enables chloride to enter the cleft and bind to exposed side chains, thereby promoting cleft opening and synergistically allowing removal of iron by the chelator, leading to a positive anion effect. Disabling one or more of the primary anion-binding residues, namely Arg-124, Lys-206 and Lys-296, substantially decreases the anion-binding ability of the resulting mutant proteins. In these cases, the competition for the remaining binding residue(s) is increased, leading to a negative chloride effect or, at most, a very small positive effect, even at low pH.

Mutation of the iron ligand His 249 to Glu in the N-lobe of human transferrin abolishes the dilysine "trigger" but does not significantly affect iron release

Serum transferrin is the major iron transport protein in humans. Its function depends on its ability to bind iron with very high affinity, yet to release this bound iron at the lower intracellular pH. Possible explanations for the release of iron from transferrin at low pH include protonation of a histidine ligand and the existence of a pH-sensitive "trigger" involving a hydrogen-bonded pair of lysines in the N-lobe of transferrin. We have determined the crystal structure of the His249Glu mutant of the N-lobe half-molecule of human transferrin and compared its iron-binding properties with those of the wild-type protein and other mutants. The crystal structure, determined at 2.4 A resolution (R-factor 19.8%, R(free) 29.4%), shows that Glu 249 is directly bound to iron, in place of the His ligand, and that a local movement of Lys 296 has broken the dilysine interaction. Despite the loss of this potentially pH-sensitive interaction, the H249E mutant is only slightly more acid-stable than wild-type and releases iron slightly faster. We conclude that the loss of the dilysine interaction does make the protein more acid stable but that this is counterbalanced by the replacement of a neutral ligand (His) by a negatively charged one (Glu), thus disrupting the electroneutrality of the binding site.

Mutations at the histidine 249 ligand profoundly alter the spectral and iron-binding properties of human serum transferrin N-lobe

Human serum transferrin is an iron-binding and -transport protein which carries iron from the blood stream into various cells. Iron is held in two deep clefts located in the N- and C-lobes by coordinating to four amino acid ligands, Asp 63, Tyr 95, Tyr 188, and His 249 (N-lobe numbering), and to two oxygens from carbonate. We have previously reported the effect on the iron-binding properties of the N-lobe following mutation of the ligands Asp 63, Tyr 95, and Tyr 188. Here we report the profound functional changes which result from mutating His 249 to Ala, Glu, or Gln. The results are consistent with studies done in lactoferrin which showed that the histidine ligand is critical for the stability of the iron-binding site [H. Nicholson, B. F. Anderson, T. Bland, S. C. Shewry, J. W. Tweedie, and E. N. Baker (1997) Biochemistry 36, 341-346]. In the mutant H249A, the histidine ligand is disabled, resulting in a dramatic reduction in the kinetic stability of the protein toward loss of iron. The H249E mutant releases iron three times faster than wild-type protein but shows significant changes in both EPR spectra and the binding of anion. This appears to be the net effect of the metal ligand substitution from a neutral histidine residue to a negative glutamate residue and the disruption of the "dilysine trigger" [MacGillivray, R. T. A., Bewley, M. C., Smith, C. A., He, Q.-Y., Mason, A. B., Woodworth, R. C., and Baker, E. N. (2000) Biochemistry 39, 1211-1216]. In the H249Q mutant, Gln 249 appears not to directly contact the iron, given the similarity in the spectroscopic properties and the lability of iron release of this mutant to the H249A mutant. Further evidence for this idea is provided by the preference of both the H249A and H249Q mutants for nitrilotriacetate rather than carbonate in binding iron, probably because NTA is able to provide a third ligation partner. An intermediate species has been identified during the kinetic interconversion between the NTA and carbonate complexes of the H249A mutant. Thus, mutation of the His 249 residue does not abolish iron binding to the transferrin N-lobe but leads to the appearance of novel iron-binding sites of varying structure and stability.