[Research on quantitative evaluation of revise requirements of Specifications of Air Sampling for Hazardous Substances Monitoring in the Workplace (GBZ 159-2004)]

Objective: To conduct quantitative evaluation on the revise requirements of Specifications of Air Sampling for Hazardous Substances Monitoring in the Workplace (GBZ 159-2004) , clarify the problems and suggestions during its implementation for improvement, and provide a basis for the revision of the standard. Methods: From April to September 2021, stratified convenient sampling method was adopted and semi-open questionnaire was used to investigate the occupational health personnel in CDC, occupational prevention and control institutes, employers, third-party technical service institutions and universitie. The entropy weight of each index and the score based on entropy weight of GBZ 159 were calculated. Spearman rank correlation analysis was used to describe the correlation between the two indexes and radar chart was drawn for comprehensive evaluation. Results: A total of 151 questionnaires were received from the respondents, of which 147 were valid, with an effective recovery rate of 97.35%, involving 29 provinces, autonomous regions and municipalities. The median G scores of the necessity and urgency of GBZ 159 revision based on entropy weight were 2.84 and 3.17, respectively, and the difference was statistically significant (M=-25.50, P<0.001) . The trend of the score G of necessity and urgency based on entropy weight was basically the same for all secondary items (r(s)=0.9998, P<0.001) , and the score G of urgency based on entropy weight was higher than that of necessity. The highest score G of necessity and urgency based on entropy weight was "3.13 long time sampling", which were 7.56 and 8.23 respectively. This was followed by "3.12 short time sampling", which were 7.19 and 7.13 respectively. Conclusion: GBZ 159 has encountered some new problems and challenges in the implementation process, and some of its technical indicators have been out of line with the actual practice of occupational health at present. These are the two items that urgently needs to be revised and improved, such as "3.13 long time sampling" and "3.12 short time sampling" and other items need to be revised and improved.

[Study on the implementation effect evaluation of Specifications of Air Sampling for Hazardous Substances Monitoring in the Workplace (GBZ 159-2004)]

Systematically evaluate the implementation of Specifications of Air Sampling for Hazardous Substances Monitoring (GBZ 159-2004) , so as to provide technical basis for the future standard revision. The semi-structured interview method was used to interview the industry experts from centers for disease control and prevention, occupational disease prevention and control hospitals/institutes, employers, third-party technical service institutions and universities, and the induction method was used to refine the topics and relevant suggestions. Some technical indicators of GBZ 159 are not suitable for the current actual work of occupational health, and need to be revised and improved urgently. The revised GBZ 159 should comply with the current situation of China's industrial development and the development of occupational health testing equipment in the new era, and improve the relevant technical requirements of sampling quality control.

[Epidemiological characteristics of local COVID-19 epidemics and control experience in routine prevention and control phase in China]

The COVID-19 pandemic is still ongoing in the world, the risk of COVID-19 spread from other countries or in the country will exist for a long term in China. In the routine prevention and control phase, a number of local COVID-19 epidemics have occurred in China, most COVID-19 cases were sporadic ones, but a few case clusters or outbreaks were reported. Winter and spring were the seasons with high incidences of the epidemics; border and port cities had higher risk for outbreaks. Active surveillance in key populations was an effective way for the early detection of the epidemics. Through a series of comprehensive prevention and control measures, including mass nucleic acid screening, close contact tracing and isolation, classified management of areas and groups at risk, wider social distancing and strict travel management, the local COVID-19 epidemics have been quickly and effectively controlled. The experiences obtained in the control of the local epidemics would benefit the routine prevention and control of COVID-19 in China. The occurrence of a series of COVID-19 case clusters or outbreaks has revealed the weakness or deficiencies in the COVID-19 prevention and control in China, so this paper suggests some measures for the improvement of the future prevention and control of COVID-19.

[Prognostic significance of different IDH mutations and accompanying gene mutations in patients with acute myeloid leukemia]

目的

探讨IDH不同突变亚型及伴发不同基因突变在非M₃型急性髓系白血病（AML）患者中的预后意义。

方法

采用二代测序技术检测2016年6月至2018年12月就诊于郑州大学第一附属医院的389例AML患者的22种基因突变情况，通过Kaplan-Meier法及Cox回归模型分析影响预后的因素。

结果

389例AML患者中，IDH1及IDH2的突变率分别为6.2%、8.7%，未发现IDH1与IDH2共突变的情况。IDH2突变型患者年龄偏大、骨髓原始细胞比例高、正常核型多见、常合并RUNX1突变及SRSF2突变。单因素方差分析发现，IDH1突变型组较野生型组的中位总生存（OS）及无进展生存（PFS）时间明显缩短（P值均<0.05）；IDH2突变作为一个单变量对预后无显著影响，不同突变位点对预后的影响不同，IDH2R140突变对预后无显著影响，IDH2R172突变型患者较IDH2野生型患者完全缓解（CR）率明显减低、中位OS及PFS时间明显缩短（P值均<0.05）。在正常核型或年龄≥50岁的患者中，IDH不同突变亚型显示出同样的预后意义。74.1%（43/58）IDH突变患者同时携带其他基因突变，伴发基因突变数目对患者的预后无显著影响，IDH突变患者中伴NPM1突变者的CR率明显高于不伴NPM1突变者（81.8%对36.4%，P＝0.014），伴DNMT3A突变者的中位OS时间短于不伴DNMT3A突变者[4.0（95%CI 3.8～4.2）个月对6.3（95%CI 2.4～10.2）个月，P＝0.041]。多因素分析显示：年龄≥60岁、WBC≥100×10⁹/L是影响患者OS及PFS的独立危险因素，2个疗程内CR、造血干细胞移植是影响患者OS及PFS的独立有利因素。

结论

在AML（非M₃型）患者中，IDH基因突变常与其他基因突变共存，IDH不同突变亚型及伴发基因突变显示出不同的预后意义。

[Clinical features and prognostic factors in adult acute myeloid leukemia patients with FLT3-ITD and CEBPA gene co-mutation]

目的

研究FLT3-ITD及CEBPA双等位基因突变(CEBPAdm)共突变成人急性髓系白血病(AML)患者的临床特征及预后。

方法

对2016年1月至2018年9月就诊于郑州大学第一附属医院的初治成人AML患者的临床资料进行回顾性研究，比较分析其临床特点及预后。基因突变检测采用直接测序法。

结果

①接受基因突变检测的非M₃且资料完整患者599例，检出FLT3-ITD基因突变阳性（FLT3-ITD⁺）且CEBPAdm阳性（CEBPAdm⁺）患者19例（A组），FLT3-ITD⁺且CEBPAdm⁻患者84例（B组），FLT3-ITD⁻且CEBPAdm⁺患者95例（C组），未检出任何已知基因突变患者70例（D组），共计268例。②A、B、C、D四组间性别、PLT、FAB分型、诱导治疗方案、融合基因突变情况差异均无统计学意义（P值均>0.05）；而发病年龄、初诊时WBC、HGB含量、外周血原始幼稚细胞比例、骨髓原始幼稚细胞比例差异均有统计学意义（P值均<0.05）。组间两两比较，A组较B、C、D组性别、年龄、HGB含量、PLT、FAB分型差异无统计学意义（P值均>0.05）。A组初诊时外周血WBC、外周血原始幼稚细胞比例、首疗程诱导治疗后微小残留病（MRD）水平高于B、C、D各组。③A、B、C、D组首疗程化疗后完全缓解（CR₁）率分别为50.0%、32.4%、59.8%、39.0%（P=0.003），复发率分别为55.6%、50.0%、21.1%、40.0%（P<0.001），中位总生存时间分别为6.25、3.0、15.5、10.5个月（P<0.001），中位无进展生存时间分别为5.0、4.0、10.0、6.7个月（P=0.032）。

结论

FLT3-ITD及CEBPAdm共突变成人AML患者初诊时外周血WBC高，外周血原始幼稚细胞比例高，首疗程诱导化疗后MRD水平高，CR₁率低，复发率高，中位总生存时间、中位无进展生存时间短，预后不佳。

Astragalus mongholicus Bunge and Panax notoginseng (Burkill) F.H. Chen Formula for Renal Injury in Diabetic Nephropathy-In Vivo and In Vitro Evidence for Autophagy Regulation

Background

Diabetic nephropathy (DN) is a serious complication of diabetes mellitus (DM) with limited treatment options. DN leads to progressive renal failure and accelerates rapidly into end-stage renal disease. Astragalus mongholicus Bunge and Panax notoginseng (Burkill) F.H. Chen formula (APF) is a traditional Chinese medicine (TCM) formula widely used to treat chronic kidney diseases (CKD) in the clinic in the southwest of China. The aim of this study is to explore how APF and its related TCM theory work on DN and whether mTOR/PINK1/Parkin signaling plays a part in this process.

Methods

HPLC was used for preliminary chemical analysis and quantitative analysis of the five components of APF. An in vivo autophagy deficiency model was established in C57BL/6 mice by streptozocin (STZ) combined with a high-fat and high-sugar diet, while the in vitro autophagy deficiency model was induced with high glucose (HG) in renal mesangial cells (RMCs). Renal histopathology staining was performed to investigate the extents of inflammation and injury. Real time-PCR and Western blotting techniques were utilized to assess autophagy-related proteins.

Results

APF significantly ameliorated renal injury in DN mice, specifically restoring blood urea nitrogen, serum creatinine, and 24-hour albuminuria. APF also reduced the mRNA and protein expressions of TNFα, IL-1β, and IL-6 in STZ-induced DN mice. Furthermore, APF improved the autophagy deficiency induced by STZ in vivo or HG in vitro, as revealed by changes in the expressions of mTOR, PINK1, Parkin, Beclin 1, p62, and LC3B. Notably, inhibition of autophagy with 3-methyladenine in APF-treated RMCs aggravated cellular damage and altered mTOR/PINK1/Parkin signaling, indicating that APF rescued HG damage through promoting autophagy.

Conclusion

APF may protect the kidneys from inflammation injuries in DN by upregulating autophagy via suppressing mTOR and activating PINK1/Parkin signaling. This experimental evidence strongly supports APF as a potential option for the prevention and treatment of DN.

[Investigation on the Influencing Factors of Adult Dyslipidemia in Shunqing District of Nanchong City]

Objective

To analyze the risk factors of dyslipidemia of adult residents in Shunqing District of Nanchong City.

Methods

A five-stage stratified cluster sampling method was used to select adult residents from 9 communities in the urban area of Shunqing District of Nanchong City from January 2013 to April 2018 for questionnaires survey,physical measurement and laboratory test. Univariate analysis and multivariate logistic regression analysis were used to study the influencing factors of dyslipidemia.

Results

A total of 105 956 people was investigated,and the prevalence rate of dyslipidemia was 34.2% (36 272 cases). Among them, the prevalence rate of male was 38.11%, and 31.91% for female ( P<0.01). The proportion of dyslipidemia with hypertension, diabetes, and coronary heart disease was 13.46%, 5.74%, and 0.39%, respectively. The proportion of hypertension with diabetes was 2.79%. Multivariate logistic regression analysis showed that gender (odds ratio ( OR)=1.276, P<0.001), body mass index ( OR=1.052, P<0.001), education level (set ≤elementary school as reference, high school OR=1.094, P<0.001, ≥graduated OR=1.185, P<0.001), smoking history ( OR=1.124, P<0.001), coronary heart disease ( OR=1.189, P<0.001), hypertension ( OR=1.148, P<0.001),sdiabetes ( OR=1.967, P<0.001), and family history of dyslipidemia ( OR=1.760, P<0.001) were the influencing factors of dyslipidemia in residents of this region. Conclusions The dyslipidemia of urban residents in Nanchong area is highly concerned with hypertension, diabetes, and coronary heart disease. Male, obesity, high education level, smoking, coronary heart disease, hypertension, diabetes, and family history of dyslipidemia are risk factors for dyslipidemia in urban residents of Nanchong area. It is necessary to actively target the above risk factors and high-risk groups.

[The Role of TSP-1-CD47 in ROS-mediated Pulmonary Fibrosis Induced by Paraquat]

Objective: Taking human A549 cells as the research object, to construct the paraquat-induced pulmonary fibrosis model in vitro, and to explore the role of TSP-1 (Thrombospondin-1, TSP-1) and its receptor CD47 in PQ-induced pulmonary fibrosis. Methods: Human A549 cells were cultured in vitro, divided into normal control group, PQ group, Anti-TSP1 group (PQ with neutralizing anti-TSP1 antibody at a final concentration of 10 μg/ml) . A549 cells were stimulated with different concentrations (50, 100, 200, 400, 600, 800, 1 000 μmol/L) for different time (12, 24, 48 h) , and then CCK8 method was used to detect the cell viability to screen out the concentration and time of half cell viability. The subsequent test will be performed at this concentration point.The morphology of the cells was observed under inverted microscope. The expression levels of Fibronectin (FN) and type I collagen were determined by Enzyme Linked Immunosorbent Assay (ELISA) . Immunocytochemistry (ICC) and Immunofluorescence (IF) were used to observe the expression of TSP-1 and CD47 protein and the co-expression.The mRNA expression of TSP-1 and CD47 was detected by Real Time PCR (RT-PCR) . The protien expression of TSP-1 and CD47 was detected by Western Blot (WB) . The levels of Reactive Oxygen Species (ROS) were measured by flow cytometry. Results: Before neutralizing anti-TSP1 antibody intervention: (1) When the time of PQ was constant, the cell viability decreased with the increase of PQ concentration. (2) The cells in the control group were closely connected, cobble-like, arranged neatly; with the increase of PQ concentration, the cell gap of PQ group gradually increased, spindle shape or long spindle shape. (3) With the increase of PQ concentration, the relative expression of FN and I collagen in PQ group was gradually increased compared with the control group in a concentration-dependent manner, and 200 μmol/L is the most obvious. (4) Compared with the control group, the mRNA level and the protein expression of TSP-1 and CD47 in PQ group was significantly increased, and 200 μmol/L is the most obvious, and Immunofluorescence showed they were co-expression in cytoplasm. (5) Compared with the normal group, the level of ROS in A549 cells was significantly increased at 24 h after PQ stimulation. (6) Compared with PQ group, the cell viability of Anti-TSP1 group was significantly increased, and the morphology changed to normal cell morphology, and the mRNA level and the protein expression of TSP-1 and CD47 decreased, and the overexpression of ROS was inhibited, and the relative expression of FN and I collagen decreased. Conclusion: PQ stimulation induced morphological changes of A549 cells, increased expression of TSP-1, CD47, FN and type I collagen, and increased production of ROS.Neutralizing anti-TSP1 antibodies against TSP-1 can partially improve the above lesions. TSP-1-CD47 may be associated with oxidative stress-mediated PQ-induced pulmonary fibrosis.

[The roles of TSP-1 and its receptor CD47 in pathogenesis of paraquat-induced pulmonary fibrosis in rats]

Objective: To establish a rat model of paraquat (PQ) -induced pulmonary fibrosis and observe the changes in thrombospondin-1 (TSP-1) and its receptor CD47 in lung tissue, and to investigate their roles in the pathogenesis of PQ-induced pulmonary fibrosis. Methods: Fifty-four clean adult male Sprague-Dawley rats were randomly divided into normal control group (n=6) and 2 h, 12 h, 1 d, 3 d, 7 d, and 14 d PQ poisoning groups (n=8 per group). A rat model of PQ poisoning was established by a single gavage of 20 wt.% PQ solution (50 mg/kg). Flow cytometry was used to determine the concentration of reactive oxygen species (ROS) in blood and lung tissue. Enzyme-linked immunosorbent assay was used to determine the concentrations of hydroxyl radicals, malondialdehyde, and hydroxyproline in lung tissue. HE staining and Masson staining were used to observe the pathological damage of lung tissue after PQ poisoning. The expression of TSP-1 and CD47 in lung tissue was measured by Immunohistochemistry. Results: Compared with the normal control group, the 2 h to 7 d PQ poisoning groups showed significant increases in ROS fluorescence intensity in red blood cells and lung tissues and the concentrations of malondialdehyde and hydroxyl radicals in lung tissue (P<0.05) , and the 14 d PQ poisoning group had a significant increase in the concentration of hydroxyproline in lung tissue (P<0.05). HE staining showed that the 2 h to 7 d PQ poisoning groups had significantly higher semiquantitative pathological scores of pulmonary alveolitis than the normal control group (P<0.05). The Masson staining showed that the 7 d and 14 d PQ poisoning groups had significantly higher semiquantitative pathological scores of pulmonary fibrosis than the normal control group (P<0.05). Compared with the normal control group, all PQ poisoning groups (except the 12 h group) had significantly increased expression of TSP-1 in lung tissue (P<0.05) , and all PQ poisoning groups (except the 1 d group) had significantly increased expression of CD47 in lung tissue (P<0.05). Within 2 h after PQ poisoning, the expression of TSP-1 and CD47 was positively correlated with the concentrations of ROS, hydroxyl radicals, and malondialdehyde and the degree of pulmonary alveolitis (P<0.01) ; at 1 d after PQ poisoning, the expression of TSP-1 and CD47 was positively correlated with the concentration of hydroxyproline in lung tissue (P<0.01) . Conclusion: The expression of TSP-1 and CD47 is closely related to oxidative stress and subsequent pulmonary fibrosis, and they may be involved in the development and progression of pulmonary alveolitis and subsequent pulmonary fibrosis in rats with PQ poisoning.

[Measurement and analysis of hand-transmitted vibration of vibration tools in workplace for automobile casting and assembly]

OBJECTIVE

To investigate the features of hand-transmitted vibration of common vibration tools in the workplace for automobile casting and assembly.

METHODS

From September to October, 2014, measurement and spectral analysis were performed for 16 typical hand tools(including percussion drill, pneumatic wrench, grinding machine, internal grinder, and arc welding machine) in 6 workplaces for automobile casting and assembly according to ISO 5349-1-2001 Mechanical vibration-Measurement and evaluation of human exposure to hand-transmitted vibration-part 1: General requirements and ISO 5349-2-2001 Mechanical vibration-Measurement and evaluation of human exposure to hand-transmitted vibration-Part 2: Practical guidance for measurement in the workplace.

RESULTS

The vibration acceleration waveforms of shearing machine, arc welding machine, and pneumatic wrench were mainly impact wave and random wave, while those of internal grinder, angle grinder, percussion drill, and grinding machine were mainly long-and short-period waves. The daily exposure duration to vibration of electric wrench, pneumatic wrench, shearing machine, percussion drill, and internal grinder was about 150 minutes, while that of plasma cutting machine, angle grinder, grinding machine, bench grinder, and arc welding machine was about 400 minutes. The range of vibration total value(ahv) was as follows: pneumatic wrench 0.30~11.04 m/s(2), grinding wheel 1.61~8.97 m/s(2), internal grinder 1.46~8.70 m/s(2), percussion drill 11.10~14.50 m/s(2), and arc welding machine 0.21~2.18 m/s(2). The workers engaged in cleaning had the longest daily exposure duration to vibration, and the effective value of 8-hour energy-equivalent frequency-weighted acceleration for them[A(8)] was 8.03 m/s(2), while this value for workers engaged in assembly was 4.78 m/s(2). The frequency spectrogram with an 1/3-time frequency interval showed that grinding machine, angle grinder, and percussion drill had a high vibration acceleration, and the vibration limit curve was recommended for those with a frequency higher than 400 min/d.

CONCLUSION

The workers who are engaged in cleaning, grinding, and a few positions of assembly and use grinding machine, angle grinder, internal grinder, and percussion drill are exposed to vibrations with a high vibration acceleration and at a high position of the frequency spectrum. The hand-transmitted vibration in the positions of cutting, polishing, and cleaning in automobile casting has great harm, and the harm caused by pneumatic wrench in automobile assembly should be taken seriously.

A meta-analysis of the effects of statin treatment on cardiovascular events and all-cause mortality in diabetic dialysis patients

OBJECTIVES

Diabetic dialysis patients have higher risk of cardiovascular disease (CVD) than general population. While statin treatment is effective in prevention of CVD and all-cause mortality in general population, the use of statin in diabetic dialysis patients remains controversial. Thus, we aimed to assess the effects of statin treatment on prevention of CVD and all-cause mortality in diabetic dialysis patients by meta-analysis.

MATERIALS AND METHODS

Pubmed, Embase and Cochrane Library were searched between each database's inception and July, 2014. Hazard ratio (HR) with 95% confidence interval (CI) for CVD and all-cause mortality was extracted from each study. The pooled analysis was performed using random-effects models by Stata 12.0.

RESULTS

Our search yielded five eligible articles including two RCTs and three observational studies. By pooled estimate, statin treatment was associated with a decreased risk of the cardiac endpoint which included cardiac death and nonfatal MI (HR=0.84, 95% CI: 0.78-0.90) and all cardiac events combined (HR=0.89, 95% CI: 0.82-0.96). There was no difference in the overall incidence of fatal or nonfatal stroke (HR=1.24, 95% CI: 0.99-1.53) and all cerebrovascular events combined (HR=1.14, 95% CI: 0.98-1.33) between statin treatment and control group. Finally, statin treatment was associated with a decreased risk of all-cause mortality (HR=0.81, 95% CI: 0.71-0.92).

CONCLUSIONS

Statin treatment may be beneficial for reducing the risk of cardiac events and all-cause mortality while have no effect on overall cerebrovascular events in diabetic dialysis patients. More RCTs were needed to validate the results.

[Causes of death in STZ-induced rat models of diabetes mellitus]

OBJECTIVE

To identify conditions that may improve the successful rate of STZ-induced rat models of diabetes mellitus (DM).

METHODS

100 male SD rats were randomly divided into control group (n = 10) and experimental group (n = 90). Rats in the experimental group were treated with intraperitoneal injection of STZ 65 mg/kg once, and were then categorized into succeeded DM model group and failed group. Their body masses and levels of fasting blood glucose (FBG), urine glucose (UG), urine protein (UP), urine routine, renal function, liver function, blood lipids and kidney hypertrophy index (KHI) were monitored and compared. Dead rats were dissected to observe diseased organs. Pathological changes of those diseased organs were examined by HE staining.

RESULTS

DM rat models were established through a single intraperitoneal injection of STZ, with a success rate of 58.89%. During the experiment, 43.33% of rats died. Compared with the rats in the failed group, the DM rat models had significantly higher levels of body mass, food intake, water intake, urine output, FBG, creatinine, blood urea nitrogen, KHI, urinary tract infections, and mortality; but lower levels of total protein, albumin and cholesterol and triglyceride (P < 0.05). Nine rats died of pulmonary edema; 19 died of renal abscess. The causes of 11 dead rats were not clear.

CONCLUSION

DM rat models can be established through a single intraperitoneal injection of STZ 65 mg/kg, but with high mortality rate. The deaths may be associated with infection, malnutrition, suffocation of lymphatic circulation, toxicity of STZ, and changes in environmental and climate conditions.

[Management of chronic kidney disease guided by the theory of Traditional Chinese Medicine: an experimental study]

OBJECTIVE

To determine the impact of Traditional Chinese Medicine on patients with chronic kidney disease (CKD).

METHODS

A total of 225 CKD patients in an outpatient department were recruited for this study, among whom 170 received regular Western and Chinese medicine treatments (control group) and 55 received treatments guided by the theory of Traditional Chinese Medicine (experimental group). The effectiveness of the treatments was determined through a pre-post comparison.

RESULTS

Significant pre-intervention differences in age (P < 0.01), stage of glomerular filtration rate (GFR) (P = 0.007) and urine protein (P < 0.01) were found between the two groups of patients. But age, gender and proteinuria were not significant predictors on clinical outcomes of the patients in the multivariate regression models. The experimental group had a greater level of decrease in blood urea nitrogen (P < 0.01) and serum creatine (P < 0. 01) than the control group. No significant differences between the groups were found in changes of uric acid (P = 0.475), urine protein (P = 0.058), urine red cells (P = 0.577), and urine white cells (P = 0.01). A greater level of increase in estimated glomerular filtration rate was found in the experimental group compared with the control (P < 0.001). The multivariate linear regression analysis identified group (B = 0.395, P < 0.001) and stage of GFR (B = 0.165, P = 0.008) as significant predictors on the outcomes of treatment.

CONCLUSION

The treatment of CKD patients guided by the theory of Traditional Chinese Medicine can improve renal function through influencing glomerular filtration rate. The effect is more prominent than the regular treatment regime.

[Investigate the effects of compound radix notoginseng on renal interstitial fibrosis and kidney-targeting treatment]

OBJECTIVE

Investigate the effects of compound Radix Notoginseng on renal interstitial fibrosis and kidney-targeting treatment.

METHODS

100 healthy Sprague-Dawley rats were randomly divided into 5 groups: Unilateral ureteral obstruction (UUO) group, sham-operation (SOR) group, Radix Notoginseng (RN) group, compound Radix Notoginseng (CRN) group and Losartan (ARB) group. After operation, RN, CRN and ARB groups were intragastric administrated with RN (3 mL/d), CRN (3 mL/d) and ARB [20 mg/(kg x d)] respectively. Each group randomly included 18 rats for statistical analysis. The histological changes of renal interstitial tissues were observed by HE, Masson and PAS staining. Total kidney collagen content was determined by measuring the amount of hydroxyproline. The mRNA of alpha-SMA, collagen I and fibronectin were reverse transcribed and quantified by real-time PCR. The expression of alpha-SMA protein was assessed by immunohistochemistry and Western blot analysis.

RESULTS

In UUO model, the obstructed kidney showed typical features of renal tubulointerstitial fibrosis, such as severe tubular loss, dilation, atrophy, infiltration of inflammatory cells, interstitial matrix deposition (P < 0.05). Partial correlation assay showed that the expression of alpha-SMA was related to the renal tubular injury (r = 0.55; P < 0.05). Administration of RN, CRN and ARB improved tubulointerstitial damage and collagen matrix accumulation induced by UUO in different degree. The expression of the alpha-SMA at mRNA and protein levels were significantly increased in the UUO group (P < 0.05), which was also suppressed by treatment with RN, CRN and ARB in different degree. Moreover, more effective role in preventing fibrosis was observed in CRN group than when compared with that of RN group.

CONCLUSION

RN and CRN can inhibit UUO-induced renal interstitial fibrosis in rats, and CRN treatment is more effective than RN in reducing interstitial fibrosis.

Ginsenoside-Rg1 protects podocytes from complement mediated injury

AIM OF THE STUDY

Podocytes injury mediated by complement complex C5b-9 is the main feature of membranous nephropathy (MN). Little work has been done to prove that ginsenoside-Rg1 could inhibit this process. Our study aims to investigate the efficacy of ginsenoside-Rg1 in protecting the podocyte from complement mediated injury.

MATERIALS AND METHODS

We chose sublethal C5b-9 induced podocyte injury as the model of MN in vitro. Ginsenoside-Rg1 was given as an intervention. Morphological changes were observed by electron microscope and fluorescence microscope. The production of reactive oxygen species (ROS) was detected by flow cytometry. The expression of the mitogen activated protein kinase (MAPK) including JNK, ERK and P38 was detected by western-blot technique.

RESULTS

Ginsenoside-Rg1 could protect foot processes of podocytes, suppress the damage of F-actin, decrease the production of ROS, and inhibit the activation of P38 kinase pathway.

CONCLUSION

These results suggest that ginsenoside-Rg1 could protect podocyte from sMAC-induced injury partly because of its antioxidant property and inhibit the activation of P38 kinase pathway.

[Leukemia inhibitory factor suppresses renal interstitial fibroblast activation induced by transforming growth factor]

OBJECTIVE

To investigate the effects of leukemia inhibitory factor (LIF) on renal interstitial fibroblast activation following induction by transforming growth factor beta 1 (TGF-beta1).

METHODS

Normal rat interstitial fibroblast cells (NRK/49F) were treated with TGF-beta1 and TGF-beta1, combining with LIF respectively for different duration with different concentration. Changes in cell morphology and expression of alpha-SMA were evaluated with electronic microscope and Western blot respectively. The collagen I in the supernatant was detected with ABC-ELISA.

RESULTS

TGF-beta1 induced renal interstitial fibroblast activation, and this was accompanied by significant morphological transformations and secretion of collagen I. Co-culturing of cells with LIF blocked the morphological transformation. In addition, LIF inhibited TGF-beta1-induced expression of alpha-SMA mRNA and protein (P < 0.01), and decreased the levels of collagen I (P < 0.01) in a dose-dependent manner.

CONCLUSION

LIF suppresses TGF-beta1-induced activation and collagen I secretion of cultured renal interstitial fibroblasts.

[Transforming growth TGF-beta1 mediates the expression of stromal cell derived factor-1 in kidney interstitial fibroblast cells in rats]

OBJECTIVE

To study the expression pattern of SDF-1 in the NRK49F cells and the role of TGF-beta1 in mediating the expression of SDF-1.

METHODS

The SDF-1 mRNA and protein expression in the NRK49F cells with or without stimulating by TGF-beta1 was assayed with RT-PCR or Western blot or Immunohistochemistry.

RESULTS

The SDF-1 mRNA expression stimulated by TGF-beta1 appeared in a time-dependent manner. The peak value appeared at 24 hours and was (2.924 +/- 0.235) times as high as the initial level. The dose-course studies suggested that TGF-beta1 stimulation resulted in marked promotion of SDF-1 mRNA expression, which peaked at the concentration of 5 ng/mL. At this concentration, the expression of SDF-1 mRNA was (2.113 +/- 0.314) times as high as that of the control. Corresponding with the pattern of mRNA expression of SDF-1, protein expression of SDF-1 was observed in NRK49F cells. A time-dependent manner was also observed in the protein expression of SDF-1 stimulated by 5 ng/mL of TGF-beta1. The protein expression of SDF-1 at 36 hours was (2.572 +/- 0.238) times as high as that of the control. TGF-beta1 neutralizing antibody reduced the expression of SDF-1 protein.

CONCLUSION

SDF-1 expresses in NRK49F cells. TGF-beta1 up-regulates the mRNA and protein expressions of SDF-1 in NRK49F cells in a time- and concentration-dependent manner. As a chemokine, the increased expression of SDF-1 induced by TGF-beta1 may play an important role in renal inflammation and fibrosis.

The role of C1GALT1C1 in lipopolysaccharide-induced IgA1 aberrant O-glycosylation in IgA nephropathy

Purpose: IgA1 aberrant O-glycosylation is one of the main pathogenetic features of IgA nephropathy (IgAN). This study attempted to determine the role of C1GALT1C1 in aberrant IgA1 O-glycosylation induced by lipopolysaccharide (LPS) and identify potential therapeutic targets in IgAN. Methods: Lymphocytes isolated from 22 patients with IgAN and 17 normal controls were cultured for 3 to 7 days with or without LPS and 5-azacytidine (5-AZA). Expression levels of C1GALT1C1 mRNA and protein were measured by real-time PCR and Western blot analysis, respectively. Concentration of IgA1 and level of O-glycosylation were determined by ELISA and Vicia villosa (VV) lectin-binding assay. Correlation analysis was performed between the expression of C1GALT1C1 protein and IgA1 O-glycosylation. Results: Lymphocytes from patients with IgAN secreted more IgA1 than that from normal controls after LPS stimulation (P=0.26, 0.002 and 0.005 on the 3rd, 5th and 7th day, respectively) which could be inhibited by 5-AZA (P=0.001, 0.025 and 0.001 on the 3rd, 5th and 7th day, respectively). Moreover, LPS stimulation could obviously inhibit C1GALT1C1 expression in patients with IgAN (decreased by 71%, 82% and 92% on the 3rd, 5th and 7th day, respectively; P < 0.001), and cause a significant decrease of IgA1 O-glycosylation compared with normal controls (P=0.004, 0.003 and 0.03 on the 3rd, 5th and 7th day, respectively). When 5-AZA was added, the level of C1GALT1C1 expression increased dramatically (1.98, 5.53 and 8.97 times on the 3rd, 5th and 7th day, respectively; P < 0.001) along with an increase of IgA1 O-glycosylation (P=0.295, 0.09 and 0.003 on the 3rd, 5th and 7th day, respectively). However, normal controls showed no significant change in C1GALT1C1 expression and IgA1 O-glycosylation after LPS stimulation (P > 0.05). Conclusion: LPS induced IgA1 aberrant O-glycosylation and suppressed C1GALT1C1 expression in patients with IgAN. Upregulation of C1GALT1C1 expression by 5-AZA could reverse the IgA1 aberrant O-glycosylation. These results suggest that C1GALT1C1 may play a key role in the regulation of IgA1 O-glycosylation.

[Effects of salidroside on tubular epithelial to myofibroblast transition under cobaltous chloride induced hypoxic status]

OBJECTIVE

To investigate the effect and possible mechanism of salidroside on the transdifferentiation of normal rat kidney tubular epithelia cells (NRK52E) under cobaltous chloride (Co) induced hypoxic status.

METHODS

Cultured NRK52E cells were divided into control group, Co group and Co plus salidroside treatment groups at a dosage of 10 micromol/L, 50 micromol/L, and 100 micromol/L. Hypoxia-inducible factor-1alpha (HIF-1alpha), a master regulator of oxygen homeostasis was measured as a marker of hypoxic status. Morphologic alteration of cells was observed by inverted phase contrast microscope. The expression of alpha-SMA in NRK52E cells was detected by fluorescent immunocytochemistry (FICC) and immunohistochemistry (IHC). The alpha-SMA and TGF-beta1 mRNA were assessed using reverse transcription-polymerase chain reaction (RT-PCR). The expressions of HIF-1alpha and alpha-SMA protein were detected by Western blot analyses. The enzyme-linked immunosorbent assay was performed to detect collagen I (Col-I) and fibronectin (FN) in the supernatant.

RESULTS

The expression of HIF-1alpha in NRK52E cells was induced by 100 micromol/L of Co in vitro. Co induced transdifferentiation of NRK52E cells, showing fibroblast-like in morphology. Salidroside partly blocked morphologic transformation of tubular epithelial cells. Salidroside decreased the expressions of alpha-SMA protein and mRNA and TGF-beta1 mRNA significantly (P < 0.05), although they were still higher than the controls (P <0 .05). Salidroside, especially in high dosage, inhibited the increase in Col-I and FN induced by Co (P < 0.05).

CONCLUSION

Hypoxia can induce tubular epithelial-myofibroblast transdifferentiation (TEMT). Salidroside improves Co-induced hypoxic status and inhibits TEMT possibly through reducing Col I and FN in NRK52E cells.

A case report of an effective treatment for diabetic foot ulcers with integration of traditional Chinese medicine and Western medicine

Diabetes contributes 75-85% of the factors predisposing to foot amputations, usually in association with infection and gangrene. The treatment of foot ulcers is expensive, and the effectiveness of treatment varies. We report herein a case of a diabetic foot ulcer that was treated with integrated traditional Chinese and Western medicine, with desirable cost-effective results. Traditional Chinese medicine (TCM) therapeutic principles include improving the spleen, nourishing yin, regulating qi, and resolving dampness, as well as activating stagnant blood. Western medicine includes wound debridement, skin grafting, and use of insulin, antibiotics, and vasodilators. The patient was treated with a holistic multidisciplinary approach (i.e., a combination of TCM and Western medicine, surgical management, education for diabetic foot care, and psychological counseling). Without this approach, the patient might have ended up with foot amputation and/or sepsis.

Chemically specific imaging of cryptosporidium oocysts using coherent anti-Stokes Raman scattering (CARS) microscopy

We demonstrate the application of coherent anti-Stokes Raman scattering microscopy for the rapid, label-free chemical imaging of waterborne pathogens. Chemically selective images of cryptosporidium were acquired in just a few seconds using coherent anti-Stokes Raman scattering microscopy, demonstrating its capability for the rapid detection of cryptosporidium at the single oocyst level. We discuss the applicability of such a technique in a near-real time automated water testing system.

Influence of ginsenoside Rg1, a panaxatriol saponin from Panax notoginseng, on renal fibrosis in rats with unilateral ureteral obstruction

Total saponins of Panax notoginseng (PNS) have been shown to ameliorate renal interstitial fibrosis. Ginsenoside Rg1, a panaxatriol saponin, is one of the major active molecules from PNS. The present study was undertaken to investigate the effect of ginsenoside Rg1 on renal fibrosis in rats with unilateral ureteral obstruction (UUO). The rats were randomly divided into 3 groups: sham-operation (n=15), UUO (n=15) and UUO with ginsenoside Rg1 treatment (n=15, 50 mg per kg body weight, intraperitoneally (i.p.) injected). The rats were sacrificed on Days 7 and 14 after the surgery. Histological examination demonstrated that ginsenoside Rg1 significantly inhibited interstitial fibrosis including tubular injury as well as collagen deposition. alpha-smooth muscle actin (alpha-SMA) and E-cadherin are two markers of tubular epithelial-myofibroblast transition (TEMT). Interestingly, ginsenoside Rg1 notably decreased alpha-SMA expression and simultaneously enhanced E-cadherin expression. The messenger RNA (mRNA) of transforming growth factor-beta1 (TGF-beta1), a key mediator to regulate TEMT, in the obstructed kidney increased dramatically, but was found to decrease significantly after administration of ginsenoside Rg1. Further study showed that ginsenoside Rg1 considerably decreased the levels of both active TGF-beta1 and phosphorylated Smad2 (pSmad2). Moreover, ginsenoside Rg1 substantially suppressed the expression of thrombospondin-1 (TSP-1), a cytokine which can promote the transcription of TGF-beta1 mRNA and the activation of latent TGF-beta1. These results suggest that ginsenoside Rg1 inhibits renal interstitial fibrosis in rats with UUO. The mechanism might be partly related to the blocking of TEMT via suppressing the expression of TSP-1.

[Effect of Astragalus mongholicus on expression of hepatocyte growth factor in SD rats with unilateral ureteral obstruction]

OBJECTIVE

To study the effect of Astragalus mongholicus (AM) on the expression of hepatocyte growth factor (HGF) in SD rats with unilateral ureteral obstruction (UUO) and to elucidate the mechanisms underlying the renoprotective effects of AM.

METHODS

Fifty four Sprague-Dawley rats were randomly divided into 3 groups: sham-operation group (SOR), UUO group (UUO) and UUO + AM group (AM). After administration of AM[10 g/ (kg x d)] for 3, 7 and 14 days,the histological changes of renal interstitial tissues were observed dynamically, and renal damage including tubular impairment and interstitial fibrosis were quantified on HE and Masson stained tissue sections. The protein expression of HGF and alpha-smooth muscle actin (alpha-SMA) was measured by immunohistochemistry. The mRNA expression of HGF and alpha-SMA were determined by real-time PCR. The expression of HGF and its receptor (C-met) were assessed by Western blot.

RESULTS

Renal damage was exacerbated and the expression of alpha-SMA was significantly increased in UUO group compared with those of SOR group (P < 0.05) at each time point. HGF and C-met expression peaked at the 7th day after UUO and then decreased greatly. After AM intervention, tubular impairment and interstitial fibrosis were alleviated, up-regulations of alpha-SMA expressions was significantly suppressed, whileas the expression of HGF and C-met were significantly increased when compared with UUO group (P < 0. 05) at each time point.

CONCLUSION

AM can ameliorate renal interstitial fibrosis induced by UUO in rats. The mechanisms of its antifibrotic effects may be related with the up-regulation of HGF and C-met expression, and the suppression of tubulo-epithelial mesenchymal transdifferentiation in renal intersitial progress.

[Effects of ginsenoside Rb1 on TGF-beta1 induced p47phox expression and extracellular matrix accumulation in rat renal tubular epethelial cells]

OBJECTIVE

To investigate the effects of Ginsenoside Rb1 (G-Rb1) on the oxidative damage and extracellular matrix accumulation in rat renal tubular epethelial cells induced by transforming growth factor-beta1 (TGF-beta1).

METHODS

Cultured normal rat renal tubular epethelial cells (NRK-52E) were divided into control group, 10 ng/mL TGF-beta1-induced group, G-Rb1 treated groups in which rat renal tubular epethelial cells were treated with different concentration of G-Rb1 (10 ng/mL, 20 ng/mL, 40 ng/mL) after TGF-beta1 induction, G-Rb1 40 ng/mL group and 100 nmol/L DPI(diphenyleneiodonium, an inhibitor of NADPH oxidase) group. Intracellular reactive oxidative species (ROS) level was measured by flowcytometry. p47phox protein expression was assessed by immunohistochemistry and western blotting method. The expressions of collagen I (Col-I) and fibronectin(FN) gene were measured by real-time PCR analysis. The protein level of Col-I and FN were quantitatively detected by enzyme-linked immunosorbent assay.

RESULTS

TGF-beta1 at 10 ng/mL significantly increased the intercellular ROS production and p47phox expression (P < 0.05). The levels of Col-I and FN were also significantly up-regulated with the stimulation of 10 ng/mL TGF-beta1 (P < 0.05). Compared to TGF-beta1-induced group, G-Rb1 and DPI depressed TGF-beta1-induced ROS production and p47phox overexpression. Meanhile, G-Rb1 and DPI decreased the levels of Col-I and FN.

CONCLUSION

G-Rb1 could inhibit TGF-beta1 induced ROS production and decrease the levels of Col-I and FN in a dose-dependent manner. The mechanism might be partly related to the suppression of p47phox expression.

[The effect of ginsenoside Rg1 on the renal interstitial fibrosis of UUO rat]

OBJECTIVE

To study the effect of ginsenoside Rg1 on the renal interstitial fibrosis caused by unilateral ureteral obstruction (UUO) of rats.

METHODS

80 healthy Sprague-Dawley rats were randomly divided into 4 groups: the UUO group (UUO), sham-operation group (SOR), ginsenoside Rg1 group (Rg1) and losartan group (ARB). From the first day after initial UUO, ARB group was intragastrically administrated with losartan 20 mg/(kg x d). UUO, Rg1 and SOR groups were intragastrically administrated with identical volume of normal saline. Rg1 group was intraperitoneally injected with ginsenoside Rg1 50 mg/(kg x d). UUO, ARB and SOR groups were intraperitoneally injected with identical volume of normal saline. At day 3, 7, 14 after UUO, 6 rats selected randomly from each group were killed. The dynamic histological changes of renal interstitial tissues were observed by HE, Masson and PAS staining. The mRNA of transforming growth factor-beta1 (TGF-beta1) was quantified by real-time PCR. The protein levels of TGF-beta1 expression were assessed by Western blot and immunohistochemical method respectively.

RESULTS

In UUO kidneys, the interstitial fibrosis including tubular atrophy, loss and dilation, inflammatory cell infiltration and interstitial matrix deposition was prominent. However, these morphological changes were notably reduced in Rg1 and ARB groups, and there was no significant difference between the two groups (P > 0.05). TGF-beta1 mRNA and protein expression were increased dramatically for UUO group at postoperative day 7 and 14 (P < 0.05). TGF-beta1 expression in Rg1 and ARB groups were significantly lower than that in UUO group (P < 0.05).

CONCLUSION

Ginsenoside Rg1 can evidently inhibit UUO-induced renal interstitial fibrosis in rat, which may be related to the down regulation of TGF-beta1 expression.

Adaptive optics for enhanced signal in CARS microscopy

We report the use of adaptive optics with coherent anti-Stokes Raman scattering (CARS) microscopy for label-free deep tissue imaging based on molecular vibrational spectroscopy. The setup employs a deformable membrane mirror and a random search optimization algorithm to improve signal intensity and image quality at large sample depths. We demonstrate the ability to correct for both system and sample-induced aberrations in test samples as well as in muscle tissue in order to enhance the CARS signal. The combined system and sample-induced aberration correction increased the signal by an average factor of approximately 3x for the test samples at a depth of 700 microm and approximately 6x for muscle tissue at a depth of 260 microm. The enhanced signal and higher penetration depth offered by adaptive optics will augment CARS microscopy as an in vivo and in situ biomedical imaging modality.

Three-dimensional imaging of chemical bond orientation in liquid crystals by coherent anti- Stokes Raman scattering microscopy

Liquid crystals are a class of industrially important materials whose optical properties make them useful particularly in display technology. Optical imaging of these materials provides information about their structure and physical properties. Coherent anti-Stokes Raman scattering (CARS) microscopy is used to provide three-dimensional chemical maps of liquid crystalline samples without the use of external labels. CARS is an optical imaging technique that derives contrast from Raman-active molecular vibrations in the sample. Compared to many other three-dimensional imaging techniques, CARS offers more rapid chemical characterization without the use of external dyes or contrast agents. The use of CARS to image chemical and orientational order in liquid crystals is demonstrated using several examples, and the limitations and benefits are discussed.

Structural properties of the proton translocating complex of the clathrin-coated vesicle

The clathrin-coated vesicle proton pump is a representative member of the new class of endomembrane proton ATPases that share an inhibitor profile which distinguishes them from classic F1F0 and E1E2-type proton pumps. The coated vesicle proton pump is a large (530 kDa) heteroligomer composed of eight polypeptides with molecular masses of 116, 70, 58, 40, 38, 34, 33 and 17 kDa. The 200-fold purified enzyme catalyses ATP-generated proton pumping when reconstituted in liposomes composed of pure lipids. Subunit function has been determined by partial reaction analysis of subunit and subcomplex activities. The isolated 17 kDa subunit, when co-reconstituted with bacteriorhodopsin, forms a dicyclohexylcarbodiimide-inhibitable proton channel. Selective removal of the 116 kDa subunit transforms the proton ATPase from a Mg2+-activatable to a Ca2+-activatable ATPase. Subsequent dissociation and reconstitution of subunits reveals that the 70, 58, 40 and 33 kDa components are required, in composite, to form a functional ATP-hydrolytic core, and that no single subunit or subcomplex deficient in these subunits can catalyse ATP hydrolysis.

Phase manipulated multi-beam holographic lithography for tunable optical lattices

We present principle and technique to actively stabilize and control the phase differences between multi-laser beams that produce stable and adjustable intensity patterns. This technique is based on a novel optical set-up and on a closed loop control over the phase difference between each pair of the input laser fields. Tunable optical lattices are demonstrated by exciting FeTPPCl-doped liquid crystals with the variable intensity patterns.

Towards CARS Endoscopy

We provide a proof-of-principle demonstration of CARS endoscopy. The design utilizes a single mode optical fiber with a focusing unit attached to the distal end. Picosecond pump and Stokes pulse trains in the near infrared are delivered through the fiber with nearly unaltered spectral and temporal characteristics at intensities needed for endoscopy. CARS endoscopic images are recorded by collecting the epi-CARS signal generated at the sample and raster scanning the sample with respect to the fiber. This CARS endoscope prototype represents an important step towards in situ chemically selective imaging for biomedical applications.

Optical studies of single molecules at room temperature

Recent developments in optical studies of single molecules at room temperature are reviewed, with an emphasis on the underlying principles and the potential of single-molecule experiments. Examples of single-molecule studies are given, including photophysics and photochemistry pertinent to single-molecule measurements, spectral fluctuations, Raman spectroscopy, diffusional motions, conformational dynamics, fluorescence resonant energy transfer, exciton dynamics, and enzymatic turnovers. These studies illustrate the information obtainable with the single-molecule approach that is hidden in ensemble-averaged measurements.

Flow and fracture in drying nanoparticle suspensions

Drying aqueous suspensions of monodisperse silica nanoparticles can fracture in remarkable patterns. As the material solidifies, evenly spaced cracks invade from the drying surface, with individual cracks undergoing intermittent motion. We show that the growth of cracks is limited by the advancement of the compaction front, which is governed by a balance of evaporation and flow of fluid at the drying surface. Surprisingly, the macroscopic dynamics of drying show signatures of molecular-scale fluid effects.

High-sensitivity coherent anti-Stokes Raman scattering microscopy with two tightly synchronized picosecond lasers

We demonstrate a significant improvement in signal-to-noise ratio in coherent anti-Stokes Raman scattering (CARS) spectroscopy/microscopy, using two highly synchronized picosecond Ti:sapphire lasers. A temporal jitter between the pulse trains from the two independent commercial lasers is reduced from a few picoseconds to ~21 fs , maintained over several hours. The tight synchronization brings the fluctuation of the CARS signal down to the shot-noise limit, leading to enhanced CARS vibrational images of living cells and polymer beads.

Polarization coherent anti-Stokes Raman scattering microscopy

We report polarization coherent anti-Stokes Raman scattering (P-CARS) microscopy that allows vibrational imaging with high sensitivity and spectral selectivity. The nonresonant background signals from both Raman scatterers and the solvent are efficiently suppressed in P-CARS microscopy. We demonstrate P-CARS imaging of unstained cells based on the contrast of the protein amide I band.

Identification and functional expression of four isoforms of ATPase II, the putative aminophospholipid translocase. Effect of isoform variation on the ATPase activity and phospholipid specificity

ATPase II, a vanadate-sensitive and phosphatidylserine-dependent Mg(2+)-ATPase, is a member of a subfamily of P-type ATPase and is presumably responsible for aminophospholipid translocation activity in eukaryotic cells. The aminophospholipid translocation activity plays an important physiological role in the maintenance of membrane phospholipid asymmetry that is observed in the plasma membrane as well as the membranes of certain cellular organelles. While the preparations of ATPase II from different sources share common fundamental properties, such as substrate specificity, inhibitor spectrum, and phospholipid dependence, they are divergent in several characteristics. These include specific ATPase activity and phospholipid selectivity. We report here the identification of four isoforms of ATPase II in bovine brain. These isoforms are formed by a combination of two major variations in their primary sequences and show that the structural variation of these isoforms has functional significance in both ATPase activity and phosholipid selectivity. Furthermore, studies with the phosphoenzyme intermediate of ATPase II and its recombinant isoforms revealed that phosphatidylserine is essential for the dephosphorylation of the intermediate. Without phosphatidylserine, ATPase II would be accumulated as phosphoenzyme in the presence of ATP, resulting in the interruption of its catalytic cycle.

Single molecule physics and chemistry

New experiments using scanning probe microcopies and advanced optical methods allow us to study molecules as individuals, not just as populations. The findings of these studies not only include the confirmation of results expected from studies of bulk matter, but also give substantially new information concerning the complexity of biomolecules or molecules in a structured environment. The technique lays the groundwork for achieving the control of an individual molecule's motion. Ultimately, this work may lead to such practical applications as miniaturized sensors.

Recombinant SFD isoforms activate vacuolar proton pumps

The vacuolar proton pump of clathrin-coated vesicles is composed of two general sectors, a cytosolic, ATP hydrolytic domain (V1) and an intramembranous proton channel, V0. V1 is comprised of 8-9 subunits including polypeptides of 50 and 57 kDa, termed SFD (Sub Fifty-eight-kDa Doublet). Although SFD is essential to the activation of ATPase and proton pumping activities catalyzed by holoenzyme, its constituent polypeptides have not been separated to determine their respective roles in ATPase functions. Recent molecular characterization of these subunits revealed that they are isoforms that arise through an alternative splicing mechanism (Zhou, Z., Peng, S.-B., Crider, B.P., Slaughter, C., Xie, X.S., and Stone, D.K. (1998) J. Biol. Chem. 273, 5878-5884). To determine the functional characteristics of the 57-kDa (SFDalpha)1 and 50-kDa (SFDbeta) isoforms, we expressed these proteins in Escherichia coli. We determined that purified recombinant proteins, rSFDalpha and rSFDbeta, when reassembled with SFD-depleted holoenzyme, are functionally interchangeable in restoration of ATPase and proton pumping activities. In addition, we determined that the V-pump of chromaffin granules has only the SFDalpha isoform in its native state and that rSFDalpha and rSFDbeta are equally effective in restoring ATPase and proton pumping activities to SFD-depleted enzyme. Finally, we found that SFDalpha and SFDbeta structurally interact not only with V1, but also withV0, indicating that these activator subunits may play both structural and functional roles in coupling ATP hydrolysis to proton flow.

Identification and reconstitution of an isoform of the 116-kDa subunit of the vacuolar proton translocating ATPase

We have identified a cDNA encoding an isoform of the 116-kDa subunit of the bovine vacuolar proton translocating ATPase. The predicted protein sequence of the new isoform, designated a2, consists of 854 amino acids with a calculated molecular mass of 98,010 Da; it has approximately 50% identity to the original isoform (a1) we described (Peng, S.-B., Crider, B. P., Xie, X.-S., and Stone, D.K. (1994) J. Biol. Chem. 269, 17262-17266). Sequence comparison indicates that the a2 isoform is the bovine homologue of a 116-kDa polypeptide identified in mouse as an immune regulatory factor (Lee, C.-K., Ghoshal, K., and Beaman, K.D. (1990) Mol. Immunol. 27, 1137-1144). The bovine a1 and a2 isoforms share strikingly similar structures with hydrophilic amino-terminal halves that are composed of more than 30% charged residues and hydrophobic carboxyl-terminal halves that contain 6-8 transmembrane regions. Northern blot analysis demonstrates that isoform a2 is highly expressed in lung, kidney, and spleen. To determine the possible role of the a2 isoform in vacuolar proton pump function, we purified from bovine lung a vacuolar pump proton channel (VO) containing isoform a2. This VO conducts bafilomycin-sensitive proton flow after reconstitution and acid activation, and supports proton pumping activity after assembly with the catalytic sector (V1) of vacuolar-type proton translocating ATPase (V-ATPase) and sub-58-kDa doublet, a 50-57-kDa polypeptide heterodimer required for V-ATPase function. These data indicate that the a2 isoform of the 116-kDa polypeptide functions as part of the proton channel of V-ATPases.

Single-molecule enzymatic dynamics

Enzymatic turnovers of single cholesterol oxidase molecules were observed in real time by monitoring the emission from the enzyme's fluorescent active site, flavin adenine dinucleotide (FAD). Statistical analyses of single-molecule trajectories revealed a significant and slow fluctuation in the rate of cholesterol oxidation by FAD. The static disorder and dynamic disorder of reaction rates, which are essentially indistinguishable in ensemble-averaged experiments, were determined separately by the real-time single-molecule approach. A molecular memory phenomenon, in which an enzymatic turnover was not independent of its previous turnovers because of a slow fluctuation of protein conformation, was evidenced by spontaneous spectral fluctuation of FAD.

Molecular characterization of the 50- and 57-kDa subunits of the bovine vacuolar proton pump

The vacuolar type proton-translocating ATPase of clathrin-coated vesicles is composed of two large domains: an extramembranous catalytic sector and a transmembranous proton channel. In addition, two polypeptides of 50 and 57 kDa have been found to co-purify with the pump. These proteins, termed SFD (sub-fifty-eight-kDa dimer) activate ATPase activity of the enzyme and couple ATPase activity to proton flow (Xie, X.-S., Crider, B.P., Ma, Y.-M., and Stone, D. K. (1994) J. Biol. Chem. 269, 28509-25815). It has also been reported that the clathrin-coated vesicle proton pump contains AP50, a 50-kDa component of the AP-2 complex responsible for the assembly of clathrin-coated pits, and that AP50 is essential for function of the proton pump (Liu, Q., Feng, Y., and Forgac, M. (1994) J. Biol. Chem. 269, 31592-31597). We demonstrate through the use of anti-AP50 antibody, identical to that of the latter study, that hydroxylapatite chromatography removes AP50 from impure proton pump preparations and that purified proton pump, devoid of AP50, is fully functional. To determine the true molecular identity of SFD, both the 50- and 57-kDa polypeptides were directly sequenced. A polymerase chain reaction-based strategy was used to screen a bovine brain cDNA library, yielding independent full-length clones (SFD-4A and SFD-21); these were identical in their open reading frames and encoded a protein with a predicted mass of 54,187 Da. The SFD-21 clone was then used in a reverse transcription-polymerase chain reaction-based strategy to isolate a related, but distinct, transcript present in bovine brain mRNA. The nucleotide and predicted amino acid sequences of this isolate are identical to SFD-21 except that the isolate contains a 54-base pair insert in the open reading frame, resulting in a protein with a predicted mass of 55,933 Da. Both clones had 16% identity to VMA13 of Saccharomyces cerevisiae. No sequence homology between the SFD clones and AP50 was detectable. Anti-peptide antibodies were generated against an epitope common to the two proteins and to the unique 18-amino acid insert of the larger protein. The former reacted with both components of native SFD, whereas the latter reacted only with the 57-kDa component. We term the 57- and 50-kDa polypeptides SFDalpha and SFDbeta, respectively.

Subunit G of the vacuolar proton pump. Molecular characterization and functional expression

The vacuolar type proton pump of clathrin-coated vesicles has a multisubunit ATP hydrolytic center that is peripheral to the membrane. Polypeptides present in this domain include the well characterized subunits A, B, C, D, E, and F; SFD, a dimer composed of 50- and 57-kDa polypeptides; and polypeptides termed G and H. Of these, subunits A, B, C, and E have been shown to be necessary but not sufficient for significant ATPase activity; in addition, either polypeptide G or H is also required for ATP hydrolysis (Xie, X.-S. (1996) J. Biol. Chem. 271, 30980-30985). In this study, the polypeptides G and H were purified and directly sequenced. Subsequent molecular analysis has revealed that these proteins are isoforms, which we designate G1 and G2. The cDNAs encoding the rat and bovine brain and chicken osteoclast forms of G1 have been cloned. The open reading frames of the rat and bovine clones encode hydrophilic proteins of 118 amino acids that differ at only five residues; bovine G1 has 36% identity with VMA10, a component of the proton channel of yeast. Northern blot analysis revealed a 1. 0-kilobase pair transcript encoding G1 in bovine brain, kidney, heart, and spleen. The cDNA encoding bovine polypeptide H was cloned and sequenced, revealing this protein to be 64% identical to G1, constituting isoform G2. In Northern blot analysis, a single 1. 7-kilobase pair transcript hybridized with a probe to G2 in brain, but not in heart, kidney, or spleen. An antibody against a bovine G1-specific domain reacts with V pump from bovine brain, kidney, and chromaffin granule, whereas an anti-G2 antibody reacts only with proton pump from brain. The bovine forms of G1 and G2 were subsequently expressed in Escherichia coli and Sf9 cells, respectively, and purified to homogeneity. Reconstitution of ATP hydrolysis was achieved by combination of recombinant subunits A, B, C, and E with either recombinant G1 or G2, demonstrating the role of these isoforms in pump function.

Reconstitution of ATPase activity from individual subunits of the clathrin-coated vesicle proton pump. The requirement and effect of three small subunits

The vacuolar-type proton pump of clathrin-coated vesicles is composed of two general domains, a peripheral, catalytic sector (VC) and a transmembranous proton channel (VB). In its native form, the enzyme can hydrolyze both MgATP and CaATP, whereas VC, when separated from VB, loses its MgATPase activity and switches to a state that can hydrolyze only CaATP. Further dissociation of VC results in subcomplexes that are depleted of one or more subunits and lack ATPase activity altogether. Reconstitution of recombinant subunits to these biochemically prepared subcomplexes has demonstrated the necessity of polypeptides of 70, 58, 40, and 33 kDa (subunits A, B, C, and E, respectively) for CaATPase activity of the VC complex. The current studies demonstrate that mixtures of these four recombinant subunits cannot support CaATPase activity in the absence of a biochemically prepared subcomplex. Investigation of the other components required for ATPase activity has led to the identification of three additional polypeptides present in preparations of VC, with apparent molecular masses of 15, 14, and 10 kDa. Each of these proteins was found to activate ATPase activity of mixtures of subunits A, B, C, and E. In addition, ATPase reconstituted from these individual subunits hydrolyses ATP, not only in the presence of Ca2+ but also in the presence of Mg2+. Investigation of the individual properties of these three subunits revealed that the 10-kDa polypeptide is subunit F, as determined by immunoblot analysis. This subunit had no effect on MgATPase activity of VC but stimulated CaATPase activity 6-fold in the presence of subunit D. Under optimal conditions the 14-kDa component resulted in a 10-fold stimulation and the 15-kDa component a 20-fold stimulation of MgATPase activity; based on this observation, the 14- and 15-kDa polypeptides were named subunits G and H, respectively. In addition, proton pumping activity was reconstituted through the reassembly of subunits A-H with VB and SFD, a previously described pump component composed of polypeptides of 50 and 57 kDa (Xie, X.-S, Crider, B.P., Ma, Y. M., and Stone, D. K. (1994) J. Biol. Chem. 269, 25809-25815). Together, these experiments completely define the catalytic center of the vacuolar proton pump of clathrin-coated vesicles.

Identification of a 14-kDa subunit associated with the catalytic sector of clathrin-coated vesicle H+-ATPase

The clathrin-coated vesicle H+-ATPase is composed of a peripheral catalytic sector (VC) and an integral membrane proton channel (VB), both of which are multiple subunit complexes. This study was conducted to determine if subunit F, previously identified in vacuolar proton pumps of tobacco hornworm and yeast, was present in mammalian pumps. Using a polymerase chain reaction-based strategy, we have isolated and sequenced cDNA clones from bovine and rat brain cDNA libraries. A full-length clone from rat brain encodes a 119-amino acid polypeptide with a predicted molecular mass of 13, 370 Da and with approximately 72 and 49% identity to subunit F of tobacco hornworm and yeast, respectively. Southern and Northern blot analyses indicate that the protein is encoded by a single gene. An anti-peptide antibody, directed against deduced protein sequence, was affinity-purified and shown to react with a 14-kDa polypeptide that is present in a highly purified pump prepared from clathrin-coated vesicles and also isolated VC. When stripped clathrin-coated vacuolars and purified chromaffin granule membranes were treated with KI in the presence of ATP, the 14-kDa subunit was released from both membranes, further indicating that it is part of the peripheral catalytic sector. In addition, direct sequencing of this 14-kDa component of the coated vacuolar proton pump confirmed its identity as a subunit F homologue.

Reconstitution of the recombinant 70-kDa subunit of the clathrin-coated vesicle H+ ATPase

Vacuolar-type proton pumps are complex heterooligomers. When dissociated into subcomplexes and subunits, the partial reactions of ATP hydrolysis and transmembranous proton flow can be assigned to isolated domains. Data suggest that the molecular site of ATP hydrolysis resides within the 70-kDa subunit but that ATPase activity likely requires at least three additional subunits of 58, 40, and 33 kDa (Xie, X.-S., and Stone, D. K. (1988) J. Biol. Chem. 263, 9859-9867). We have now cloned and sequenced the 70-kDa subunit from bovine brain and have expressed the protein in insect Sf9 (Spodoptera frugiperda) cells with a recombinant baculovirus. When purified, the protein has no significant ATPase activity but can be photoaffinity labeled with [alpha 32P]ATP and UV irradiation with an apparent Kd of 35 microM. When reconstituted with biochemically prepared 58-, 40-, and 33-kDa polypeptides, the recombinant 70-kDa subunit restores Ca(2+)-activated ATP hydrolysis to a specific activity of 0.6 mumol P(i).mg protein-1.min-1, thus demonstrating that ATP hydrolysis in vacuolar-type proton pumps is dependent upon both the 70-kDa subunit as well as multi-subunit interactions.

Role of a 50-57-kDa polypeptide heterodimer in the function of the clathrin-coated vesicle proton pump

The vacuolar-type proton-translocating ATPase of clathrin-coated vesicles is composed of an integral membrane proton channel (VB) and a peripheral catalytic sector (VC). Native enzyme can catalyze the hydrolysis of both MgATP and CaATP and support proton pumping when reconstituted into liposomes. In contrast, isolated VC catalyzes only Ca(2+)-activated ATP hydrolysis and cannot support proton pumping when reconstituted into liposomes (Xie, X.-S., and Stone, D. K. (1988) J. Biol. Chem. 263, 9859-9867). We now report that solubilized isolated VC can be reassembled with purified VB to restore properties of native enzyme, including Mg(2+)-activated ATP hydrolysis and proton-pumping capability. Investigation of this reassembly revealed that a heterodimer, composed of polypeptides of 50 and 57 kDa, stimulates Ca(2+)-activated ATPase activity of isolated VC 2-fold and Mg(2+)-activated ATPase activity catalyzed by the reassembled pump 9-fold. Moreover, this heterodimer stimulated proton transport by the reassembled pump > 20-fold. When separated from the proton pump, the dimer has no detectable kinase activity. Maximal stimulation occurs at a molar ratio of heterodimer to reassembled pump of 3, implying a structural, nonenzymatic mechanism. These data indicate that the 50-kDa and/or the 57-kDa polypeptide likely plays an essential and potentially regulatory role in the function of the proton-translocating ATPase of clathrin-coated vesicles.