[Epidemiological study of incidence of systematic lupus erythematosus in Yinzhou, Ningbo, 2016-2021]

Objective: To characterize the incidence density of systematic lupus erythematosus (SLE) in Yinzhou District of Ningbo from 2016 to 2021, and compare the age and gender specific differences. Methods: A retrospective cohort study was conducted based on the related data from 2015 to 2021 collected from the Health Information Platform of Yinzhou. Suspected SLE cases in local residents were identified by fuzzy matching of International Classification of Diseases 10^th edition code "M32" or Chinese text "lupus". The classification criteria from Systemic Lupus International Collaboration Clinics-2012 and The European League Against Rheumatism/American College of Rheumatology-2019 were used for case verification. SLE cases were identified with specific algorithm based on verification results, and new cases were identified with 1 year as the washout period. The incidence density and 95%CI were estimated by Poisson distribution. Results: From 2016 to 2021, a total of 1 551 921 permanent residents were registered in Yinzhou, in whom 51.52% were women. The M(Q₁,Q₃) age at enrollment was 40.38 (27.54, 53.54) years. The M(Q₁,Q₃) of follow-up person-years was 3.83 (0.41, 5.83) years. There were 451 new SLE cases, in which 352 were women (78.05%). The 6-year incidence density was 8.14/100 000 person-years (95%CI: 7.41/100 000 person-years-8.93/100 000 person-years) for the total population, 3.68/100 000 person-years (95%CI: 2.99/100 000 person-years-4.48/100 000 person-years) for men and 12.37/100 000 person-years (95%CI: 11.11/100 000 person-years- 13.73/100 000 person-years) for women. The incidence density in men appeared a small peak at 20-29 years old, and began to increase with age from 40 years old. The incidence density in women was highest in age group 20-29 years (16.57/100 000 person-years) and remained to be high until 30-79 years old. The incidence density of SLE in Yinzhou show no significant temporal trend from 2016 to 2021 (men: P=0.848; women: P=1.000). Conclusions: The incidence density of SLE in Yinzhou from 2016 to 2021 was similar to those of other areas in China. SLE has a high incidence in women, especially in the young and elderly, suggesting that more attention should be paid to the diagnosis and treatment of SLE in women.

[Prevalence and treatment of anemia in chronic kidney disease patients based on regional medical big data]

Objective: To assess the prevalence, risk factors and treatment of anemia in patients with chronic kidney disease (CKD). Methods: A descriptive method was used to analyze the prevalence and treatment of anemia in CKD patients based on regional health data in Yinzhou District of Ningbo during 2012-2018. The multivariate logistic regression analysis was used to identify independent influence factors of anemia in the CKD patients. Results: In 52 619 CKD patients, 15 639 suffered from by anemia (29.72%), in whom 5 461 were men (26.41%) and 10 178 were women (31.87%), and anemia prevalence was higher in women than in men, the difference was significant (P<0.001). The prevalence of anemia increased with stage of CKD (24.77% in stage 1 vs. 69.42% in stage 5, trend χ2 test P<0.001). Multivariate logistic regression analysis revealed that being women (aOR=1.57, 95%CI: 1.50-1.63), CKD stage (stage 2: aOR=1.10, 95%CI: 1.04-1.16;stage 3: aOR=2.28,95%CI: 2.12-2.44;stage 4: aOR=4.49,95%CI :3.79-5.32;stage 5: aOR=6.31,95%CI: 4.74-8.39), age (18-30 years old: aOR=2.40,95%CI: 2.24-2.57, 61-75 years old: aOR=1.35,95%CI:1.28-1.42, ≥76 years old: aOR=2.37,95%CI:2.20-2.55), BMI (<18.5 kg/m2:aOR=1.29,95%CI: 1.18-1.41;23.0-24.9 kg/m2:aOR=0.79,95%CI: 0.75-0.83;≥25.0 kg/m2:aOR=0.70,95%CI: 0.66-0.74), abdominal obesity (aOR=0.91, 95%CI: 0.86-0.96), chronic obstructive pulmonary disease (aOR=1.15, 95%CI: 1.09-1.22), cancer (aOR=3.03, 95%CI: 2.84-3.23), heart failure (aOR=1.44, 95%CI: 1.35-1.54) and myocardial infarction (aOR=1.54, 95%CI:1.16-2.04) were independent risk factors of anemia in CKD patients. Among stage 3-5 CKD patients with anemia, 12.03% received iron therapy, and 4.78% received treatment with erythropoiesis-stimulating agent (ESA) within 12 months after anemia was diagnosed. Conclusions: The prevalence of anemia in CKD patients was high in Yinzhou. However, the treatment rate of iron therapy and ESA were low. More attention should be paid to the anemia management and treatment in CKD patients.

[A risk prediction model of cervical cancer developed based on nested case-control design]

Objective: To construct a cervical cancer risk prediction model based on nested case-control study design and Yinzhou Health Information Platform in Ningbo, and provide reliable reference for self-risk assessment of cervical cancer in local women. Methods: In local women aged 25-75 years old who had no history of cervical cancer registered in Yinzhou before October 31, 2018, a follow up was conducted for at least three years, the patients who developed cervical cancer during the follow up period were selected as the case group and matched with a control group at a ratio of 1∶10. The prediction indicators before the onset was used in model construction. Variables were selected by Lasso-logistic regression, the variables with non-zero β were selected to fit the logistic regression model and Bootstrap was used for internal validation. The discrimination of the model was evaluated by area under the receiver operating characteristic curve(AUROC), and the calibration was evaluated by calibration curve and Hosmer-Lemeshow test. Results: The prediction indicators included in the final model were age, smoking status, history of cervicitis, history of adenomyosis, HPV testing, and thinprep cytologic test. The AUROC calculated in the internal validation was 0.740 (95%CI:0.739-0.740), and the calibration curve was almost identical with the ideal curve, P=0.991 in Hosmer-Lemeshow test, indicating that the model discrimination and calibration were good. Conclusions: In this study, a simple and practical cervical cancer risk prediction model was developed. The model can be used in general population with strong interpretability, good discrimination and calibration in internal validation, which can provide a reference for women to assess their risk of cervical cancer.

[Comparison of aspirin treatment strategies for primary prevention of cardiovascular diseases: A decision-analytic Markov modelling study]

OBJECTIVE

To compare the expected population impact of benefit and risk of aspirin treatment strategies for the primary prevention of cardiovascular diseases recommended by different guidelines in the Chinese Electronic Health Records Research in Yinzhou (CHERRY) study.

METHODS

A decision-analytic Markov model was used to simulate and compare different strategies of aspirin treatment, including: Strategy ①: Aspirin treatment for Chinese adults aged 40-69 years with a high 10-year cardiovascular risk, recommended by the 2020 Chinese Guideline on the Primary Prevention of Cardiovascular Diseases; Strategy ②: Aspirin treatment for Chinese adults aged 40-59 years with a high 10-year cardiovascular risk, recommended by the 2022 United States Preventive Services Task Force Recommendation Statement on Aspirin Use to Prevent Cardiovascular Disease; Strategy ③: Aspirin treatment for Chinese adults aged 40-69 years with a high 10-year cardiovascular risk and blood pressure well-controlled (< 150/90 mmHg), recommended by the 2019 Guideline on the Assessment and Management of Cardio-vascular Risk in China. The high 10-year cardiovascular risk was defined as the 10-year predicted risk over 10% based on the 2019 World Health Organization non-laboratory model. The Markov model simulated different strategies for ten years (cycles) with parameters mainly from the CHERRY study or published literature. Quality-adjusted life year (QALY) and the number needed to treat (NNT) for each ischemic event (including myocardial infarction and ischemic stroke) were calculated to assess the effectiveness of the different strategies. The number needed to harm (NNH) for each bleeding event (including hemorrhagic stroke and gastrointestinal bleeding) was calculated to assess the safety. The NNT for each net benefit (i.e., the difference of the number of ischemic events could be prevented and the number of bleeding events would be added) was also calculated. One-way sensitivity analysis on the uncertainty of the incidence rate of cardiovascular diseases and probabilistic sensitivity analysis on the uncertainty of hazard ratios of interventions were conducted.

RESULTS

A total of 212 153 Chinese adults, were included in this study. The number of people who were recommended for aspirin treatment Strategies ①-③ was 34 235, 2 813, and 25 111, respectively. The Strategy ③ could gain the most QALY of 403 [95% uncertainty interval (UI): 222-511] years. Compared with Strategy ①, Strategy ③ had similar efficiency but better safety, with the extra NNT of 4 (95%UI: 3-4) and NNH of 39 (95%UI: 19-132). The NNT per net benefit was 131 (95%UI: 102-239) for Strategy ①, 256 (95%UI: 181-737) for Strategy ②, and 132 (95%UI: 104-232) for Strategy ③, making Strategy ③ the most favorable option with a better QALY and safety, along with similar efficiency in terms of net benefit. The results were consistent in the sensitivity analyses.

CONCLUSION

The aspirin treatment strategies recommended by the updated guidelines on the primary prevention of cardiovascular diseases showed a net benefit for high-risk Chinese adults from developed areas. However, to balance effectiveness and safety, aspirin is suggested to be used for primary prevention of cardiovascular diseases with consideration for blood pressure control, resulting in better intervention efficiency.

[Epidemiological study on the incidence of rheumatoid arthritis in adults in Yinzhou district, Ningbo city from 2011-2020]

Objective: To describe the distribution and trend of rheumatoid arthritis (RA) in adults in the Yinzhou district from 2011 to 2020 and compare the incidence differences in different ages and genders. Methods: Using the retrospective cohort design, we collected all new cases diagnosed with RA between 2011 to 2020 from the Yinzhou Regional Health Information Platform (YRHIP). Poisson distribution was used to estimate RA's incidence density and 95%CI. Results: From 2011 to 2020, 1 280 012 permanent residents in Yinzhou district were included, of which 665 361 were female (51.98%). The total follow-up person-years were 7 198 513.61, and the median follow-up person-year was 5.41 years (P₂₅=3.50, P₇₅=8.32). During the study period, there were 2 350 new cases of RA, of which 1 460 were female (62.13%). The 10-year incidence density of the population was 32.65/100 000 person-years (95%CI: 31.34/100 000 person-years-33.99/100 000 person-years), that of females was 39.17/100 000 person-years (95%CI: 37.19/100 000 person-years-41.24/100 000 person-years), and that of the male was 25.64/100 000 person-years (95%CI: 23.98/100 000 person-years-27.38/100 000 person-years), the gender difference was statistically significant (P<0.001). The incidence risk in all age groups above 30 years old was higher than that in the 18-29 years old group (P<0.001), and the incidence risk increased with age from 18-79 years old while decreased slightly with age ≥80 years old. The lowest incidence density was 15.30/100 000 person-years in 2013 (95%CI:12.62/100 000 person-years-18.38/100 000 person- years), and the highest was 56.70/100 000 person-years in 2016 (95%CI: 51.24/100 000 person- years - 62.58/100 000 person-years), with statistically significant differences among different years (P=0.004). Conclusions: From 2011 to 2020, the incidence density of RA in adults in Yinzhou district first increased, then decreased, and tended to stabilize. There were differences in incidence density in different years, ages, and genders.

[Accuracy of the China-PAR and WHO risk models in predicting the ten-year risks of cardiovascular disease in the Chinese population]

Objective: To externally validate and compare the accuracy of the China-PAR (Prediction for ASCVD Risk in China) model and the 2019 World Health Organization (WHO) cardiovascular disease risk charts for East Asian in predicting a 10-year cardiovascular disease in a general Chinese population. Methods: Participants aged 40-79 years without prior cardiovascular disease at baseline in the CHinese Electronic health Records Research in Yinzhou (CHERRY) were analyzed. The Kaplan-Meier analysis estimated the observed cardiovascular events (including non-fatal myocardial infarction, fatal coronary heart disease, and non-fatal or fatal stroke) rate within ten years. The expected risks were calculated using the WHO risk charts for East Asia (including the laboratory-based and non-laboratory-based models) and the China-PAR model. The expected-observed ratios were calculated to evaluate the overestimation or underestimation of the models in the cohort. Model accuracy was assessed by discrimination C-index, calibration χ² value, and calibration plots. Results: During a median of 7.26 years of follow-up, 13 301 cardiovascular events were identified among 225 811 participants. The C-index for the China-PAR model, WHO laboratory-based model and WHO non-laboratory-based model were 0.741 (0.735-0.747), 0.747 (0.740-0.753), and 0.739 (0.733-0.746) for men, and 0.782 (0.776-0.788), 0.789 (0.783-0.795), and 0.782 (0.776-0.787) for women, respectively. The WHO laboratory-based model and non-laboratory-based model underestimated the 10-year ASCVD risk by around 15% in women and underestimated by 0.8% and 4.4% in men, respectively. The China-PAR model underestimated the risks by 19.5% and 42.3% for men and women. Conclusions: The China-PAR and WHO models all have pretty good discriminations for 10-year cardiovascular risk assessment in this general Chinese population. However, the accuracy should be improved in the highest-risk groups, suggesting further specific models are still needed for those with the highest risk, such as patients with diabetes or older persons.

[Effectiveness of statin treatment strategies for primary prevention of cardiovascular diseases in a community-based Chinese population: A decision-analytic Markov model]

OBJECTIVE

To evaluate the effectiveness of statin treatment strategies based on risk assessment for the primary prevention of cardiovascular diseases by the Western guidelines in a community-based Chinese population from economically developed areas using data from the Chinese electronic health records research in Yinzhou (CHERRY) study.

METHODS

A Markov model was used to evaluate the effectiveness of the following statin treatment strategies, including: (1) usual care without cardiovascular risk assessment(Strategy 0); (2) using the World Health Organization (WHO) non-laboratory-based risk charts with statin treatment for high-risk group (risk ≥ 20%) (Strategy 1); (3) using the WHO laboratory-based risk charts with statin treatment for high-risk group (risk ≥ 20%) (Strategy 2); and (4) using the Prediction for Atherosclerotic cardiovascular disease Risk in China (China-PAR) model with statin treatment for high-risk group (risk ≥ 10%, Strategy 3). According to the guidelines, adults in the medium-risk group received lifestyle intervention, and adults in the high-risk group received life-style intervention and statin treatment under these strategies. The Markov model simulated different strategies for ten years (cycles) using parameters from the CHERRY study, published data, meta-analyses and systematic reviews for Chinese. The number of cardiovascular events or deaths, as well as the number need to treat (NNT) with statin per cardiovascular event or death prevented, were calculated to compare the effectiveness of different strategies. One-way sensitivity analysis on the uncertainty of incidence rate of cardiovascular diseases, and probabilistic sensitivity analysis on the uncertainty of hazard ratios of interventions were conducted.

RESULTS

Totally 225 811 Chinese adults aged 40-79 years without cardiovascular diseases at baseline were enrolled. In contrast to the usual care without risk assessment-based statin treatment strategy, Strategy 1 using the WHO non-laboratory-based risk charts could prevent 3 482 [95% uncertainty interval (UI): 2 110-4 661] cardiovascular events, Strategy 2 using the WHO laboratory-based risk charts could prevent 3 685 (95%UI: 2 255-4 912) events, and Strategy 3 using the China-PAR model could prevent 3 895 (95%UI: 2 396-5 181) events. NNTs with statin per cardiovascular event prevented were 22 (95%UI: 14-54), 21 (95%UI: 14-52), and 27 (95%UI: 17-67), respectively. Strategy 3 could prevent more cardiovascular events, while Strategies 1 and 2 required fewer numbers need to treat with statin per cardiovascular event prevented. The results were consistent in the sensitivity analyses.

CONCLUSION

The statin treatment strategies based on risk assessment for the primary prevention of cardiovascular diseases recommended by the Western guidelines could achieve substantive health benefits in adults from developed areas of China. Using the China-PAR model for cardiovascular risk assessment could prevent more cardiovascular diseases while using the WHO risk charts seems more efficient.

[Applications of the NDR and DIAL models for risk prediction on cardiovascular disease in patients with type 2 diabetes in Ningbo]

Objective: To validate the performance of cardiovascular risk prediction models based on the Sweden National Diabetes Register (NDR) and Diabetes Lifetime-perspective prediction (DIAL) model for assessing risks of 5-year and 10-year cardiovascular disease (CVD) among Chinese patients with type 2 diabetes. Methods: Based on the Chinese Electronic Health Records Research in Yinzhou study, 83 503 patients with type 2 diabetes aged 30-75 years without a history of CVD at baseline were included from January 1, 2010 to December 31, 2020. Recalibrated NDR model was used to estimate 5-year risk, while the recalibrated DIAL model was used to predict 5-year and 10-year risks. The competing events adjusted Kaplan-Meier analysis was used to obtain the observed cardiovascular events. Discrimination C statistics evaluated model accuracy, calibration χ² value, and calibration plots. Results: Through a median follow-up of 7.0 years, 7 326 cardiovascular events, and 2 937 non-vascular deaths were identified among a total of 83 503 subjects. The recalibrated NDR model overestimated 5-year risk by 39.4% in men and 8.6% in women, whereas the overestimation for the recalibrated DIAL model was 14.6% in men and 50.1% in women. The DIAL model had a better discriminative ability (C-statistic=0.681, 95%CI: 0.672-0.690) than NDR model (C-statistic=0.667, 95%CI: 0.657-0.677) in 5-year risk prediction for men, and the models had a similar ability for women (C-statistic=0.699, 95%CI: 0.690-0.708 for NDR and C-statistic=0.698, 95%CI: 0.689-0.706 for DIAL). The prediction accuracy of the DIAL model was improved in the 10-year risk, with the underestimation being 1.6% for men and the overestimation being 12.8% for women. Conclusions: Both recalibrated NDR and DIAL models overestimated 5-year cardiovascular risk in Chinese patients with type 2 diabetes, while the higher overestimation was shown using the DIAL model. However, the improvement was found in predicting 10-year CVD risk using the DIAL model, which suggested the value of lifetime risk prediction and indicated the need for research on the lifetime risk prediction model for cardiovascular risk assessment in Chinese patients with type 2 diabetes.

[Association of high-density lipoprotein cholesterol with risk of cardiovascular disease mortality]

Objective: To analyze the association between high density lipoprotein cholesterol (HDL-C) and the risk of cardiovascular disease mortality. Methods: A total of 71 618 residents aged over 18 years with complete baseline data, who were filed on the health information big data platform of Yinzhou district, Ningbo city, Zhejiang Province from 2009 to 2014, were selected as the research population. The research population were divided into four groups according to the level of HDL-C: low-level group (HDL-C<1.0 mmol/L), intermediate-level group (1.0 mmol/L≤HDL-C<1.5 mmol/L), medium-high-level group (1.5 mmol/L≤HDL-C<2.0 mmol/L) and high-level group (HDL-C≥2.0 mmol/L). Cox proportional hazard model was used to calculate the risk ratio of cardiovascular diseases mortality in different groups. Results: The study population was followed up for a total of 427 989.4 person-years, follow-up time of (5.98±1.04)years. During the follow-up period, there were 799 deaths due to cardiovascular diseases. After adjusting for confounding factors, compared with the medium-high-level group as the reference group, the HR (95%CI) for cardiovascular diseases mortality was 1.43 (1.13-1.82) in the low-level group and 1.22 (1.02-1.46) in the high-level group. Conclusion: The low level of HDL-C (<1.5 mmol/L) is associated with a higher risk of cardiovascular disease deaths. The level of HDL-C can be used as a biological indicator to monitor the development of cardiovascular diseases and guide treatment.

[Application of multi-state Markov model in studying transition of number of chronic complications and influencing factors in type 2 diabetes mellitus patients]

Objective: To establish a multi-state Markov model of type 2 diabetes mellitus (T2DM) patients and explore the transition rule between the cumulative number of different chronic complications, estimate the transition probability and intensity between status, and explore the possible factors affecting the transition between status. Methods: A retrospective cohort study of 33 575 patients with T2DM was conducted. According to the baseline and the cumulative number of chronic complications during the follow-up period, the patients were classified based on five status: T2DM, one complication, two complications, three complications, four and above complication, indicated by S0, S1, S2, S3 and S4, respectively. A time-continuous and state-discrete multi-state irreversible Markov model was used for statistical analysis. Results: The study included 33 575 T2DM patients, and their average age was 60 years old, the median of follow-up length was 8 years. In these patients, 32 653 had no baseline complications. At the end of follow-up, the transition probabilities of S0→S1, S1→S2, S2→S3 and S3→S4 were 16.4%, 32.4%, 45.6% and 25.9%, respectively. The results of multivariate analysis showed that being female (HR=0.919), less than 60 years old (HR=0.929), higher fasting plasma glucose (HR=1.601), lower high-density lipoprotein (HR=1.087), higher total cholesterol (HR=1.090),weekly exercise (HR=0.897), vegetarian diet (HR=0.852) and heavy diet (HR=1.887) were the risk factors for S0 to S1. And being female (HR=0.768), less than 60 years old (HR=0.859) and lower high-density lipoprotein (HR=1.160) were the risk factors for S1 to S2. Conclusions: The probability of multiple complications in T2DM patients increased over time, the transition intensity of S2→S3 was largest, followed by S1→S2. Therefore, we need to conduct both early and long-term indicators monitoring and disease prevention, strengthen the health education to improve patients' daily living habits at early stage of the illness, encourage patients to have moderate exercise and balanced diet, strengthen the monitoring of fasting blood- glucose, cholesterol and high-density lipoprotein levels to prevent the deterioration of the illness.

Resveratrol alleviates osteoporosis through improving the osteogenic differentiation of bone marrow mesenchymal stem cells

OBJECTIVE

To investigate the protective effect of Resveratrol (RES) on TNF-α-induced inhibition of osteogenic differentiation, thus alleviating the progression of osteoporosis (OP).

MATERIALS AND METHODS

OP model in rats was first conducted by performing ovariectomy (OVX). Rats were randomly divided into sham group, OVX group, and RES+OVX group. Body weight of each rat was regularly recorded every week. Bone mineral density (BMD) of rat femoral metaphysis was measured by micro-CT. Changes in radial degrees and loads of rat femora were examined through three-point bending experiments. Relative levels of OCN and Runx2 in each group were determined by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). Alkaline phosphatase (ALP) activity and calcification ability were assessed through ALP staining and alizarin red staining, respectively. Bone mesenchymal stem cells (BMSCs) were extracted from healthy rats and divided into control group, Tumor necrosis factor-α (TNF-α) group, RES group, and TNF-α+RES group based on different treatments. Relative levels of OCN and Runx2, ALP activity, and calcification ability in each group were detected in the same way. Finally, protein levels of NF-κB and β-catenin in BMSCs were determined.

RESULTS

Rats in each group gained body weight during the experimental period, especially those in OVX group and RES+OVX group. No significant difference in the body weight was found between OVX group and RES+OVX group. BMD in rat femora of RES+OVX group was higher than in OVX group but lower than sham group. Elastic/max radial degree and elastic/max load of femora were markedly reduced in OVX group compared to RES+OVX group. Relative levels of OCN and Runx2, ALP activity and calcification ability decreased in OVX group relative to sham group, which were partially reversed by RES treatment. After osteogenic differentiation in BMSCs induced with TNF-α, viability and calcification ability were markedly reduced and were upregulated by RES treatment. Moreover, RES treatment enhanced the downregulated levels of OCN and Runx2 in BMSCs undergoing TNF-α induction. Upregulated protein levels of nuclear factor kappa-B (NF-κB) and β-catenin in TNF-α-induced BMSCs were downregulated by RES treatment.

CONCLUSIONS

The inhibited osteogenic differentiation of BMSCs undergoing TNF-α induction is improved by resveratrol treatment, which contributes to alleviate the progression of osteoporosis.

[Epidemiological characteristics of COVID-19 monitoring cases in Yinzhou district based on health big data platform]

Objective: To understand the epidemiological characteristics of COVID-19 monitoring cases in Yinzhou district based on health big data platform to provide evidence for the construction of COVID-19 monitoring system. Methods: Data on Yinzhou COVID-19 daily surveillance were collected. Information on patients' population classification, epidemiological history, COVID-19 nucleic acid detection rate, positive detection rate and confirmed cases monitoring detection rate were analyzed. Results: Among the 1 595 COVID-19 monitoring cases, 79.94% were community population and 20.06% were key population. The verification rate of monitoring cases was 100.00%. The total percentage of epidemiological history related to Wuhan city or Hubei province was 6.27% in total, and was 2.12% in community population and 22.81% in key population (P<0.001). The total COVID-19 nucleic acid detection rate was 18.24% (291/1 595), and 53.00% in those with epidemiological history and 15.92% in those without (P<0.001).The total positive detection rate was 1.72% (5/291) and the confirmed cases monitoring detection rate was 0.31% (5/1 595). The time interval from the first visit to the first nucleic acid detection of the confirmed monitoring cases and other confirmed cases was statistically insignificant (P>0.05). Conclusions: The monitoring system of COVID-19 based on the health big data platform was working well but the confirmed cases monitoring detection rate need to be improved.

[Incidence and risk factors of chronic kidney disease in community-based patients with diabetes]

OBJECTIVE

To estimate the incidence rate and effects of risk factors on chronic kidney disease (CKD) in Chinese patients with diabetes, based on Electronic Health Records (EHRs) from the Chinese Electronic health Records Research in Yinzhou (CHERRY) Study.

METHODS

Using the CHERRY cohort study with the individual-level information on chronic disease management; and health administrative, clinical and laboratory databases, patients with diabetes without kidney disease at baseline were enrolled and followed up from January 2009 through December 2016. CKD was defined as the estimated glomerular filtration rate(eGFR) <60 mL/(min×1.73 m²) or urine albumin/creatinine ratio (ACR)≥3 mg/mmol. Standardized incidence rates of CKD in diabetic population were calculated according to the 2010 China census data. Cox proportional hazards models were used to explore the association of risk factors on CKD in patients with diabetes.

RESULTS

Over a median 3.2 years of follow-up, 13 829 patients with diabetes were included in this analysis and 1 087 developed CKD. The crude and standardized incidence rate was 23.7(95%CI: 22.3-25.2) and 14.8(95%CI:12.1-17.6) per 1 000 person-years respectively. The incidence rate for developing CKD in patients with diabetes aged over 60 years was higher than those aged 60 and below (26.6 vs. 11.5 per 1 000 person-years, P<0.05). Cox proportional hazards models showed that age over 60 years(HR=1.88, 95%CI: 1.51-2.35), hypertension (HR=1.81, 95%CI: 1.56-2.10), total cholesterol (HR=1.07, 95%CI: 1.00-1.14) and duration of diabetes (HR per year increment=1.02, 95%CI: 1.00-1.03) and the level of high density lipoprotein cholesterol (HDLC, HR=0.49, 95%CI: 0.40-0.61) were significantly associated with CKD. No statistical significance was found for sex, smoking status, alcohol use and average level of fasting glucose (All P>0.05). Subgroup analysis indicated that even when the lipid levels were well-controlled, comorbidity of hypertension was still associated with CKD in the patients with diabetes.

CONCLUSION

Incidence rate of chronic kidney disease in this Chinese population with diabetes was high. Age and comorbidity of hypertension were the most important risk factors for CKD, suggesting the priority for CKD screening in patients with diabetes in China. Control of blood pressure and lipid were especially crucial to prevent CKD in patients with diabetes.

[Clinical effect of minimally-Invasive surgical-transforaminal lumbar interbody fusion technique associated with percutaneous pedicle screws in micro endoscopy discectomy]

Objective: To evaluate the clinical efficacy between the minimally-Invasive surgical (MIS)-transforaminal lumbar interbody fusion (TLIF) technique associated with percutaneous pedicle screws in micro endoscopy discectomyand MIS-TLIF technique associated with both sides of the lower lumbar spine Wiltse approach in Quadrant channel with treatment of single segment herniation associated with lumbar instability syndrome. Methods: From January 2012 to January 2015, 75 cases that meet the inclusion and exclusion criteria were treated by retrospective study method, which were divided into two groups in Department of Orthopedics, the Affiliated Hospital of Putian University.Experimental group(30 patients) were treated with MIS-TLIF technique associated with percutaneous pedicle screws in microendoscopy discectomy, control group were treated with MIS-TLIF technique associated with both sides of the lower lumbar spine Wiltse approach in Quadrant Chanel.Compare operation time, blood loss, postoperativehospital stay, clinical efficacy, nailing accuracy, fusion rate, postoperative pain scoring of two groups. Results: The blood loss[(102.1±5.5) min vs(103.7±7.7) min, t=-0.586, P>0.05], postoperative blood loss, hospital stay[(44.6±5.2) ml and(57.2±5.3) ml, (7.3±1.6) d and(9.3±1.9) d; t=-5.813, -2.774, P<0.05], JOA score before and after surgery in same group were statistically significant(P<0.05), respectively.Patients of two groups compared with operation time, clinical efficacy, nailing accuracy[group A: 97.5%, group B: 95.7%; χ(2)=3.00, P>0.05.Postoperative 3 month , group A: 96.7%(29/30), group B: 94.3%(33/35; χ(2)=0.79, P>0.05], fusion rate[group A: 96.7%(29/30), group B: 94.3%(33/35), χ(2)=0.79, P>0.05], preoperative JOA score[(20.4±2.4)score and(7.9±1.0), (19.1±2.7)score and(7.8±1.2)score], postoperative JOA score were no statistically significant respectively, P>0.05. JOA score of both groups were statistically significant respectively Before and after operate.Excellent rate: group A; 84.4%(25/30), group B: 80.0%(28/35), χ(2)=0.43, P>0.05. Conclusion: MIS-TLIF technique associated with percutaneous pedicle screws in micro endoscopy discectomy relative to conventional minimally invasive spine surgery had many advantages: minimal damage, operation conveniently, precisely clinical effect, that is a kind of feasible and reliable minimally invasive surgery which is worth promoting.

High-performance cavity-phase matching by pump reflection

Since cavity-phase matching has been experimentally realized, the efficiency is limited to 20%. In this Letter, we successfully achieved a conversion efficiency as high as 41% with a slope efficiency of 48.5% using cavity-phase matching, by reflecting the pump beam at the end surface of the KTiOPO(4) crystal. The high performance of the device makes it a promising candidate to substitute for quasi-phase-matching material.

The effect of candesartan on the pharmacokinetics of enalaprilat in nephrotic rats

BACKGROUND AND OBJECTIVES

The adverse reactions in combination of angiotensin-converting enzyme inhibitors (ACEIs) and Ang II receptor blockers (ARBs) were severer than that in monotherapy for patients with nephropathy. The effect of candesartan on pharmacokinetics of enalaprilat in nephrotic rats was investigated to make references for the clinical therapy in patients with nephropathy to avoid related adverse effects.

MATERIALS AND METHODS

Nephrotic rats were prepared by adriamycin injection. Control group and one nephrotic group received enalapril alone, another nephrotic group received enalapril and candesartan simultaneously. Blood samples were drawn at time points after a single oral administration. The concentration of enalaprilat was determined using LC-MS/MS.

RESULTS

Compared with control group and nephrotic group received enalapril alone respectively, Tmax of enalaprilat in nephrotic group received both enalapril and candesartan cilexetil prolonged about 21.43% and 6.224%, respectively; AUC(0-t) increased by 185.3% and 60.63%, respectively; Cmax increased by 219.4% and 56.64%, respectively; t1/2 increased by 163.7% and 30.05%, respectively; CL/F reduced by 65.12% and 40.78%, respectively. There were no significant differences of the V1/F of enalaprilat between three groups. The CL/F and t1/2 of enalaprilat showed significant correlations with serum creatinine (Scr) respectively (r = -0.7502; r = 0.5626).

DISCUSSION

The combination with candesartan in nephrotic rats significantly changed the pharmacokinetics of enalaprilat, showing increased accumulation and decreased elimination. In view of these findings, we should lower dosage and prolong dosing interval for nephrotic patients in the combination of enalapril and candesartan.

Promiscuous initiation on mammalian chromosomal DNA templates and its possible suppression by transcription

The Chinese hamster dihydrofolate reductase (DHFR) origin consists of many inefficient initiation sites scattered throughout a 55-kb intergenic spacer, with the ori-beta, ori-beta', and ori-gamma subregions being preferred. To test for the presence of genetic replicators within these subregions, fragments containing ori-beta, ori-beta', or, as a negative control, a fragment from the DHFR gene that never initiates in loco were placed at ectopic chromosomal positions. Two-dimensional gel analysis demonstrates that initiation occurs in all three fragments, including the fragment from the gene, and appears to occur at different positions within each fragment in different cells in the population. However, initiation is not detectable in the adjacent, transcribed, neomycin-resistance marker. When a cosmid containing an active DHFR gene was inserted into an ectopic chromosomal site, initiation could no longer be observed in the body of the gene, but was clearly evident in the transcriptionally-silent bacterial vector sequences. In the thirteen independent chromosomal positions into which the four different constructs were inserted, initiation occurred in early S-phase. Since these loci necessarily had to be permissive for transcription of the neo(r) marker or DHFR gene used to select transfectants, it is possible that early-firing origin activity and local transcription are somehow linked. In total, these data suggest that potential initiation sites are distributed at very frequent intervals in the mammalian genome, with usage being regulated both positively and negatively by local transcription.

Dr. Gary J. Becker young investigator award: comparison of small-diameter type 1 collagen stent-grafts and PTFE stent-grafts in a canine model--work in progress

PURPOSE

To report an in-progress experiment in a canine model in which two types of small-diameter stent-grafts-one constructed of polytetrafluoroethylene (PTFE) and the other of a new, type 1 collagen material-were compared regarding vessel patency, intimal hyperplasia formation, and tissue reaction.

MATERIALS AND METHODS

Six mongrel dogs weighing 30-35 kg were used. Stent-grafts of 4-mm diameter and 20-mm length were constructed with use of balloon-expandable stainless-steel stents wrapped with either PTFE or a new type 1 collagen graft. Stent-grafts were placed in deep femoral arteries bilaterally (PTFE on one side, collagen on the other). Animals were followed for 2 weeks (n = 2), 6 weeks (n = 2), or 12 weeks (n = 2). Percent stenosis based on angiographic findings as well as thickness and area of neointimal hyperplasia were compared at each time point and compared with use of the Student t test.

RESULTS

All devices were patent in the immediate postimplantation period. Five of six collagen stent-grafts and five of six PTFE implants were patent at follow-up. In-stent stenosis was undetectable angiographically in all five patent collagen stent-grafts. All five patent PTFE stent-grafts showed demonstrable in-stent stenosis (10%-60%), indicating a trend toward improved patency in collagen stent-grafts versus PTFE stent-grafts (P = .07). Neointimal hyperplasia was absent at 2 weeks in the collagen stent-grafts. Neointimal thickness increased to a maximum of 360 microm at 12 weeks in the collagen stent-grafts. For PTFE stent-grafts, neointimal hyperplasia was present in all samples and reached a maximum of 770 microm at 12 weeks (P = .03).

CONCLUSIONS

Even in small-diameter vessels, type 1 collagen stent-grafts demonstrate excellent patency rates and favorable histologic findings. The type 1 collagen stent-graft technology merits further developmental efforts in preclinical models.

[Radiosensitivity of different ploidy pollen in poplar and its application]

Through investigation on germinating rate and process of unreduced diploidy pollen and monoploid pollen in Populus tomentosa x P. alba and P. tomentosa, it was proved that there were different radiosensitivities to 60Co gamma-ray among different ploidy pollen, i.e. the radiosensitivity of monoploidy pollen was two times higher than diploidy pollen. To overcome the problems of late germination and poor compatibility of diploidy pollen during fertilization, a certain dose of radiation can be applied to stimulating the diploidy pollen germination, meanwhile to restrain of kill some monoploidy pollen based on their different radiosensibilities. Therefore the rate of germination and faster germinating process of diploidy pollen on stigmas can be increased relatively to certain extent. The efficiency of radiation was proved by breeding practice. In the hybidization of (P. alba x P. glandulosa) x (P. tomentosa x P. bolleana), 3.8% of triploid could be produced by 1,470 rad treatment; while no triploid is examined in the control. 12.9% of triploids were produced by the treatment of 1,680 rad from the above cross.

Bovine type I collagen as an endovascular stent-graft material: biocompatibility study in rabbits

PURPOSE

To study the biocompatibility of a bovine type I collagen preparation as a material for small-vessel stent-grafts in rabbits.

MATERIALS AND METHODS

A composite nitinol-collagen endovascular stent-graft with a 4-mm inner diameter was deployed in the abdominal aorta in nine rabbits. Angiography was performed, and the rabbits were sacrificed at 1, 2, and 7 days and at 1 and 3 months. The portion of the aorta containing the stent-graft was excised and was histologically evaluated.

RESULTS

All stent-grafts were patent at all time points. On days 1, 2, and 7 after implantation, scattered red and white blood cells adhered to the stent-graft. At 1 month, the stent-graft was endothelialized and was infiltrated with fibroblasts that deposited collagen within the interstices of the implanted collagen material. At 3 months, there was additional collagen deposition within the interstices of the stent-graft that did not narrow the lumen of the stent-grafts.

CONCLUSION

Type I collagen as a intravascular stent-graft material is biocompatible for at least 3 months in rabbits. It is rapidly endothelialized and does not cause reactive stenosis. As a versatile and biocompatible polymer, collagen is potentially useful in the construction of endovascular stent-grafts for use in human arteries.

Identification of COUP-TF as a transcriptional repressor of the c-mos proto-oncogene

The c-mos proto-oncogene is specifically expressed in the male and female germ cells of the mouse and other vertebrates. We previously identified a 15-base pair sequence element (B2) as the binding site of a candidate repressor of c-mos transcription in somatic cells. In the present study, we used the yeast one-hybrid system to isolate HeLa cell cDNAs encoding proteins that specifically bound to the c-mos B2 element. Nucleotide sequencing identified several of the clones isolated in this screen as the orphan nuclear receptors COUP-TFI and COUP-TFII. A COUP-TF-binding site was then identified within the B2 sequence. Complexes formed between purified COUP-TFs and the c-mos B2 probe comigrated in electrophoretic mobility shift assays with those formed using whole nuclear extracts of NIH 3T3 or HeLa cells. Moreover, the complexes formed with NIH 3T3 nuclear extracts and B2 probe were supershifted with antibody against COUP-TF, identifying COUP-TF as the candidate repressor previously detected in these somatic cell extracts. Substitution of a consensus COUP-TF-binding site for the c-mos negative regulatory element suppressed expression from the c-mos promoter in transfected somatic cells, demonstrating the functional activity of COUP-TF as a repressor of c-mos transcription.

Excitation localization principle for spherical microcavities

Van de Hulst's localization principle relates the principal mode number to the external beam position that maximizes energy coupling to a spherical cavity mode. Our experiments in lasing microdroplets verify localization but only for low- Q modes, when the cavity may be considered to be a nearly perfect homogeneous sphere. The principle fails in the perturbation-dominated high- Q limit. Surprisingly, near-surface resonances are still efficiently excited in these cases but require impact parameters slightly smaller than the sphere radius. Numerical modeling suggests that this new input channel depends on surface scattering.

Distal sequences, but not ori-beta/OBR-1, are essential for initiation of DNA replication in the Chinese hamster DHFR origin

In the Chinese hamster dihydrofolate reductase replication initiation zone, the ori-beta locus is preferred over other start sites. To test the hypothesis that ori-beta contains a genetic replicator, we restored a deletion in the 3' end of the DHFR gene with a cosmid that provides the missing sequence and simultaneously knocks out the downstream ori-beta locus. Replication initiates normally in ori-beta knockout cell lines, and the DHFR domain is still synthesized in early S phase. However, initiation is completely suppressed in the starting deletion variant lacking the 3' end of the gene. We conclude that ori-beta does not contain an essential replicator, but that distant sequence elements have profound effects on origin activity in this locus.

In vivo evaluation of a new type I collagen hemostatic plug for high-risk, large-core biopsies

PURPOSE

To evaluate in a swine model the hemostatic properties of a new, expansile type I collagen plug for use in high-risk renal biopsies.

MATERIALS AND METHODS

Highly purified bovine type I collagen was formed into porous cylindrical plugs and compressed radially to fit into a 5-F delivery system. On hydration these collagen plugs demonstrated radial expansion with approximately 1,600% volumetric expansion ratio. Direct exposure of both kidneys was performed in a 25-kg swine, and a bolus of 3,000 U of heparin was administered to create a coagulopathic state. A 14-gauge Temno coaxial biopsy gun was utilized in performing nine pairs of renal biopsies. The first biopsy of each biopsy pair represented the control biopsy (without collagen plug placement), whereas the second biopsy of each pair represented the plugged biopsy. The presence and duration of hemorrhage from each biopsy site was monitored visually.

RESULTS

The biopsy sites without collagen plug showed immediate hemorrhage in nine of nine cases (100%), and in two of nine cases (22%) pulsatile bleeding was noted. With the use of the collagen plug, seven of nine (78%) sites showed immediate hemorrhage, but in no case was pulsatile bleeding noted. Mean bleeding duration was 156 seconds for the control biopsies versus 73 seconds for the biopsy sites plugged with collagen (P = .03, Mann-Whitney rank sum test). Bleeding duration was less than 1 minute in only one of nine (11%) control biopsies compared to six of nine (67%) collagen plug biopsies.

CONCLUSIONS

A recently developed, expansile collagen hemostatic plug significantly decreases the duration of hemorrhage at renal biopsy sites in an anticoagulated swine model.

Selective visual masking in speechreading

Using digital video technology, selective aspects of a face can be masked by identifying the pixels that represent it and then, by adjusting the gray levels, effectively eliminate that facial aspect. In groups of young adults with normal vision and hearing, consonant-viseme recognition was measured for closed sets of vowel-consonant-vowel disyllables. In the first experiment viseme recognition was measured while the tongue and teeth were masked and while the entire mouth was masked. The results showed that masking of the tongue and teeth had little effect on viseme recognition, and when the entire mouth was masked, participants continued to identify consonant visemes with 70% or greater accuracy in the /a/ and /(ball)/ vowel contexts. In the second experiment, viseme recognition was measured when the upper part of the face and the mouth were masked and when the lower part of the face and the mouth were masked. The results showed that when the mouth and the upper part of the face were masked, performance was poor, but information was available to identify the consonant-viseme /f/. When the mouth and the lower part of the face were masked, viseme recognition was quite poor, but information was available to discriminate the consonant-viseme /p/ from other consonant visemes.

Two-dimensional photonic bandgap optical limiter in the visible

Operation of a two-dimensional photonic bandgap optical limiter was studied at 514.5 nm for pulse durations of 0.1 to 4 ms . Photonic crystals consisted of 180- 230-nm spatial-period nanochannel glasses containing a thermal nonlinear liquid. A dynamic range in excess of 130 was observed in a single-element device.

Characterizing replication intermediates in the amplified CHO dihydrofolate reductase domain by two novel gel electrophoretic techniques

Using neutral/neutral and neutral/alkaline two-dimensional (2-D) gel techniques, we previously obtained evidence that initiation can occur at any of a large number of sites distributed throughout a broad initiation zone in the dihydrofolate reductase (DHFR) domain of Chinese hamster ovary (CHO) cells. However, other techniques have suggested a much more circumscribed mode of initiation in this locus. This dichotomy has raised the issue whether the patterns of replicating DNA on 2-D gels have been misinterpreted and, in some cases, may represent such noncanonical replication intermediates as broken bubbles or microbubbles. In an accompanying study (R. F. Kalejta and J. L. Hamlin, Mol. Cell. Biol. 16:4915-4922, 1996), we have shown that broken bubbles migrate to unique positions in three different gel systems and therefore are not likely to be confused with classic replication intermediates. Here, we have applied a broken bubble assay developed from that study to an analysis of the amplified DHFR locus in CHO cells. This assay gives information about the number and positions of initiation sites within a fragment. In addition, we have analyzed the DHFR locus by a novel stop-and-go-alkaline gel technique that measures the size of nascent strands at all positions along each arc in a neutral/neutral 2-D gel. Results of these analyses support the view that the 2-D gel patterns previously assigned to classic, intact replication bubbles and single-forked structures indeed correspond to these entities. Furthermore, potential nascent-strand start sites appear to be distributed at very frequent intervals along the template in the intergenic region in the DHFR domain.

Near-infrared two-dimensional photonic band-gap materials

We describe the fabrication and optical transmission of two-dimensional periodic dielectric structures with photonic band gaps in the near infrared. The structures consist of triangular arrays of air cylinders embedded in a glass matrix, with center-to-center nearest-neighbor separations between 1.08 and 0.73 microm. The band gaps corresponding to the first Brillouin zone's boundaries occur at wavelengths between 2.5 and 1.1 microm. For each array size, the band gaps along the two high-symmetry propagation directions are spectrally overlapped for light polarized perpendicular to the cylinder axes. The observed positions, widths, and polarization dependence of the band gaps are in good agreement with theoretical calculations.

Mimosine targets serine hydroxymethyltransferase

The plant amino acid, mimosine, is an extremely effective inhibitor of DNA replication in mammalian cells (Mosca, P. J., Dijkwel, P. A., and Hamlin, J. L. (1992) Mol. Cell. Biol. 12, 4375-4383). Mimosine appears to prevent the formation of replication forks at early-firing origins when delivered to mammalian cells approaching the G1/S boundary, and blocks DNA replication when added to S phase cells after a lag of approximately 2.5 h. We have shown previously that [3H]mimosine can be specifically photocross-linked both in vivo and in vitro to a 50-kDa polypeptide (p50) in Chinese hamster ovary (CHO) cells. In the present study, six tryptic peptides (58 residues total) from p50 were sequenced by tandem mass spectrometry and their sequences were found to be at least 77.5% identical and 96.5% similar to sequences in rabbit mitochondrial serine hydroxymethyltransferase (mSHMT). This assignment was verified by precipitating the [3H]mimosine-p50 complex with a polyclonal antibody to rabbit cSHMT. The 50-kDa cross-linked product was almost undetectable in a mimosine-resistant CHO cell line and in a CHO gly- cell line that lacks mitochondrial, but not cytosolic, SHMT activity. The gly- cell line is still sensitive to mimosine, suggesting that the drug may inhibit both the mitochondrial and the cytosolic forms. SHMT is involved in the penultimate step of thymidylate biosynthesis in mammalian cells and, as such, is a potential target for chemotherapy in the treatment of cancer.

Radial profiling of microdroplets using cavity-enhanced Raman spectroscopy

The composition of 7.7-microm-radius methanol-water droplets was radially resolved by cavity-enhanced Raman spectroscopy. Optical cavity modes, encompassing well-defined radial zones within each droplet, were sequentially excited by a 514.5-nm laser beam to generate spontaneous Raman scattered light. The cavity-enhanced Raman spectral peaks gave information as to the identity and amount of species present. The measured radial and time dependence of the methanol concentration agreed with a diffusion-limited evaporation mode.

Surface and blood-contacting properties of alkylsiloxane monolayers supported on silicone rubber

Self-assembled monolayers of alkylsiloxanes supported on polydimethyl siloxane (PDMS) rubber were used as model systems to study the relation between blood compatibility and surface chemistry. The inner lumen of PDMS tubes was first treated with an oxygen plasma. The resultant oxidized surfaces were postderivatized by reacting them with alkyltrichlorosilanes to form the monolayer films. The chemical properties of the monolayers were controlled by varying the head-group chemical compositions. Surface derivatization was verified using variable-angle X-ray photoelectron spectroscopy (XPS or ESCA). Blood compatibility was evaluated using a canine ex vivo arteriovenous series shunt model. Surfaces grafted with hydrophobic head-groups as -CH3 and -CF3 had significantly lower platelet and fibrinogen deposition than the surfaces composed of hydrophilic groups such as -CO2CH3, -(CH2CH2O)3COCH3, and -(OCH2CH2)3OH.

Mimosine, a novel inhibitor of DNA replication, binds to a 50 kDa protein in Chinese hamster cells

We recently demonstrated that the plant amino acid, mimosine, is an extremely efficacious inhibitor of DNA replication in mammalian cells [P. A. Dijkwel and J. L. Hamlin (1992) Mol. Cell. Biol. 12, 3715-3722; P. J. Mosca et al. (1992) Mol. Cell. Biol. 12, 4375-4383]. Several of its properties further suggested that mimosine might target initiation at origins of replication, which would make it a unique and very useful inhibitor for studying the regulation of DNA synthesis. However, mimosine is known to chelate iron, a cofactor for ribonucleotide reductase. Thus, the possibility arose that mimosine functions in vivo simply by lowering intracellular deoxyribonucleotide pools. In the present study, we show that, in fact, it is possible to override mimosine inhibition in vivo by adding excess iron; however, copper, which is not a substitute for iron in ribonucleotide reductase, is equally effective. Evidence is presented that mimosine functions instead by binding to an intracellular protein. We show that radiolabeled mimosine can be specifically cross-linked to a 50 kDa polypeptide (termed p50) in vitro. Binding to p50 is virtually undetectable in CHO cells selected for resistance to 1 mM mimosine, arguing that p50 is the biologically relevant target. p50 is not associated with the cellular membrane fraction and, hence, is probably not a channel protein. Furthermore, the binding activity does not vary markedly as a function of cell cycle position, arguing that p50 is not a cyclin. Finally, both iron and copper are able to reverse the mimosine-p50 interaction in vitro, probably explaining why both metal ions are able to overcome mimosine's inhibitory effect on DNA synthesis in vivo.

Synthesis, surface, and cell-adhesion properties of polyurethanes containing covalently grafted RGD-peptides

In an attempt to improve endothelial cell adhesion and growth on a polyurethane copolymer, cell adhesive RGD-containing peptides were grafted to the polymer backbone. Two peptide grafting reaction schemes, including one-step and two-step approaches, were developed. FTIR and amino acid analysis confirmed that coupling of the peptide to the polyurethane backbone was achieved by both the one-step and two-step methods. However, the two-step approach showed a higher peptide coupling efficiency and resulted in better control of the orientation of the grafted peptide. The two-step reaction scheme was used to prepare Gly-Arg-Gly-Asp-Ser-Tyr (GRGDSY), Gly-Arg-Gly-Asp-Val-Tyr (GRGDVY), and Gly-Arg-Gly-Glu-Ser-Tyr (GRGESY) peptide-grafted polyurethanes with two different peptide densities (100 and 250 mumol/g polymer). Dynamic contact angle measurements indicated that the surfaces of the peptide-grafted polyurethanes were more hydrophilic than the starting and carboxylated versions of the precursor polyurethane. In addition, the surface hydrophilicity of the peptide-grafted polymers increased with increasing bulk peptide density. Electron spectroscopy for chemical analysis suggested that the grafted peptide was present at the polymer-air interface, in vacuo, for the peptide-grafted polyurethanes. The surface peptide density appeared to correlate with the incorporated peptide density in the bulk. In vitro endothelial cell adhesion experiments showed that, without the presence of serum in culture medium, the GRGDSY- and GRGDVY-grafted polyurethanes dramatically enhanced cell attachment and spreading compared with the starting, carboxylated, and GRGESY-grafted polymers. Increasing the peptide density from 100 to 250 mumol/g polymer for the GRGDSY- and GRGDVY-grafted polyurethanes resulted in an increase in cell attachment. With approximately the same peptide density (100 or 250 mumol/g polymer), the GRGDVY-grafted polymers supported more adherent cells than did the GRGDSY-grafted polymers. Similar trends were observed in the in vitro endothelial cell growth studies using culture medium containing serum and endothelial cell growth supplement. The GRGDSY- and GRGDVY-grafted polyurethanes promoted more cell growth than did the starting polyurethane. However, the presence of adhesive serum proteins and growth factor diminished the differences between the cell-adhesive peptide grafted polymers and the GRGESY-grafted polymers.

Effect of protein adsorption on the blood-contacting response of sulphonated polyurethanes

Polyurethanes which are grafted with propyl sulphonate functionality have excellent blood-contacting properties. In a canine ex vivo series shunt experiment, very low platelet deposition was observed on these materials and those platelets which were adherent remained unspread. In contrast to this, large amounts of fibrinogen, of the order of a monolayer or greater, were deposited on these surfaces in this ex vivo experiment. This led to the hypothesis that perhaps the deposited fibrinogen did not retain its platelet-adhesive activity. In this paper, we investigate the possibility that these materials exert their antithrombotic effects through the adsorbed protein layer. Protein adsorption kinetics and isotherms on these sulphonated polyurethanes are determined. Multilayer protein adsorption or absorption into the hydrogel-like materials is found for each of the proteins studied, and the greatest amounts of protein are seen on the most highly sulphonated polyurethanes. Further, the blood-contacting response of these materials is investigated after pre-conditioning with either fibrinogen, fibronectin or albumin. When these materials are pre-adsorbed with either fibrinogen or fibronectin, a very thrombogenic response was observed, which suggests that the platelet-adhesive activity of these proteins is not being reduced. Pre-adsorption of albumin did not improve the thromboresistance of these surfaces.

Surface properties of RGD-peptide grafted polyurethane block copolymers: variable take-off angle and cold-stage ESCA studies

Variable take-off angle and cold-stage ESCA measurements were utilized to analyze the surface composition of five polyurethane block copolymers. The polymers studied included a PTMO-polyurethane control, a carboxylated version of the control polyurethane, and three different peptide grafted (GRGESY, GRGDSY, and GRGDVY) polyurethanes. On dry samples the nitrogen signal detected using ESCA decreased with increasing take-off angle (i.e. as the specimen was probed closer to the surface) for all five polymers. This was believed to be due to the depletion of nitrogen-containing urethane hard segments at the surface. For all five polymers, the surface nitrogen concentration, associated with the hard segment, increased upon hydration. A greater increase of nitrogen concentration was observed for the peptide grafted polymers which suggests that grafting of the hydrophilic peptides to the polyurethane augments the hard segment enrichment at the surface upon hydration. Upon dehydration, the nitrogen concentration decreased for all five polymers suggesting migration of the more hydrophobic PTMO soft segment to the surface. In vitro endothelial cell adhesion showed an increase of cell attachment on prehydrated RGD-containing peptide grafted polyurethanes, but not on the other polymers. This result suggests an enhancement of peptide density at the aqueous interface, in good agreement with the ESCA studies.

Continuous-wave stimulated Raman scattering in microdroplets

Continuous-wave stimulated Raman scattering was observed in 11-13-microm-diameter benzene and toluene microdroplets at pump intensities as low as 8 and 24 kW/cm(2), respectively. Low thresholds were achieved by exploiting simultaneous pump and Stokes wave resonance in the droplets and Raman gains that were cavity QED enhanced ~50 times with respect to bulk liquid values. Based on a photon-state conservation argument, the cavity gain enhancement factor may be approximated by the ratio of the spectral spacing between resonant modes of the same order to that of the homogeneous Raman linewidth. This relation appears to be consistent with the relative experimental behavior of benzene, ethanol, and toluene.

Cavity-mode identification of fluorescence and lasing in dye-doped microdroplets

Recent advances in an aerosol-generation technique have permitted the accurate identification of optical resonance-mode features of micrometer-sized freely falling droplets for several different optical processes. Both input and output resonant features of fluorescence and lasing from dye-doped microdroplets were assigned to specific spherical cavity modes by using two independent procedures: (1) by matching observed fixed-angle elastic laser light scattering as a function of droplet size to calculated scattering intensities from the Lorenz-Mie theory, and (2) by matching observed resonance peaks to computed cavity-mode positions by automated correlation. Agreement between these two complementary techniques establishes high confidence in the resulting mode identifications. Assignments of observed emission peaks provide insight into droplet-emission mechanisms.

Synthesis of a novel polyurethane co-polymer containing covalently attached RGD peptide

The synthesis of a novel polyurethane block co-polymer containing a covalently attached, well-oriented RGD (Arg-Gly-Asp) peptide was explored. A poly(tetramethylene oxide) (PTMO)-based polyurethane was synthesized, and a bimolecular nucleophilic substitution reaction was then employed to incorporate ethyl carboxylate groups onto the polymer backbone (i.e. carboxylated polyurethane). Elemental analysis was used to determine the extent of carboxylation. The hexapeptide H-Gly-Arg-Gly-Asp-Ser-Tyr-OH was coupled to the carboxylated polyurethane via the formation of an amide bond. The attachment of the peptide was controlled by a protection-deprotection scheme. Nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopies were used to monitor the reactions. Sakaguchi assay and amino acid analysis confirmed that the RGD-containing peptide was successfully grafted onto the carboxylated polyurethane. This reaction scheme provides a new route for grafting end-linked, bioactive peptides onto polyurethanes.

Endothelial cell adhesion on polyurethanes containing covalently attached RGD-peptides

Peptides based on cell-adhesive regions of fibronectin, Arg-Gly-Asp-Ser (RGDS), and vitronectin, Arg-Gly-Asp-Val (RGDV), were covalently bound to a polyurethane backbone via amide bonds. Nuclear magnetic resonance (NMR) and Fourier-transform infrared (FTIR) spectroscopies were used to monitor the reactions. The amount of grafted peptide was determined by amino acid analysis. X-ray photoelectron spectroscopy (XPS) suggested the presence of the grafted peptide at the polymer-air interface in vacuo. Dynamic contact angle analysis showed that, in water, the peptide-grafted polyurethane surfaces were more polar than the underivatized polyurethane indicating enrichment of peptide groups at the surface. The attachment and spreading of human umbilical vein endothelial cells (HUVECs) on the underivatized and peptide-grafted polyurethanes was investigated. The GRGDSY- and GRGDVY-grafted substrates supported cell adhesion and spreading even without serum in the culture medium. The GRGDVY-grafted substrate supported a larger number of adherent cells and a higher extent of cell spreading than the GRGDSY-grafted substrate. These RGD-containing peptide-grafted polyurethane copolymers may be useful in providing an easily prepared cell-adhesive substrate for various biomaterial applications.

Absorption effects on microdroplet resonant emission structure

The effect of absorption on microdroplet resonance emission line intensities was studied in 15-microm-diameter Rhodamine 6G/ethanol solution droplets. Absorption was controlled by varying the concentration of the additive nigrosin. Spectrally integrated intensities of resonant features are found to be proportional to a droplet cavity mode efficiency Q(a)/(Q(a)+Q(o)) expressed in terms of cavity output coupling and absorption factors Q(o) and Q(a), respectively. These Q's are determined from linewidths calculated from Lorenz-Mie theory by using combinations of the real and complex indices of refraction. An experimental upper limit of Q for first-order modes was determined to be 10(8) from the data.

Effects of preceding context on the voice-onset-time category boundary

The category boundary on a voice-onset-time (VOT) continuum ranging from bin to pin shifts when the stimuli are preceded by different carrier phrases. By using a variety of precursor phrases, by varying the temporal interval between precursor and test word, and by selectively eliminating either voicing information or spectral structure from the precursors, the present experiments show that the context effect is caused by the presence or absence of voicing in the precursor's final segment. The effect decreases with temporal separation but persists over several seconds. In addition, the "baseline" VOT boundary for isolated test words interspersed in a test sequence shifts depending on what precursor stimuli occur in the same sequence. The perception of VOT thus seems to be sensitive to both close and distant manifestations of laryngeal activity, always in an assimilative fashion, which suggests an integrative perceptual mechanism with a long time constant.

Stimulation of renin release by hyperkalemia in the nonfiltering kidney

This study was designed to analyze the acute effects of hyperkalemia on renin release in the normal filtering kidney and the nonfiltering kidney. Plasma K was increased by acute intravenous KCl infusion. In the normal filtering kidney experiment plasma K was 5.7 vs. 3.5 meq/l. Hyperkalemia resulted in a 45% increase in renal blood flow (RBF) and a 35% increase in glomerular filtration rate (GFR) at the 120-mmHg pressure level. Renin release was significantly greater in the hyperkalemic group than in the control group (P less than 0.01) with the greatest effect over the lower pressure range. In the nonfiltering kidney experiment plasma K was 6.09 vs. 3.5 meq/l. RBF was 33% greater in the hyperkalemic than in the normokalemic group at the 130-mmHg pressure level. Renin release was also greater in the hyperkalemic group than in the normokalemic group (P less than 0.01). However, unlike the normal filtering kidney experiments, in the nonfiltering kidneys the difference in renin release was most prominent at the highest level of renal perfusion pressure. These experiments demonstrate that acute hyperkalemia can cause renal vasodilation and stimulate renin release in both filtering and nonfiltering kidney preparations and that potassium may affect renin release both through a direct effect on the juxtaglomerular cells and indirectly by affecting delivery of fluid and/or NaCl to the macula densa.

Effects of preceding context on the voice-onset-time-category boundary

The category boundary on a voice-onset-time (VOT) continuum ranging from bin to pin shifts when the stimuli are preceded by different carrier phrases. By using a variety of precursor phrases, by varying the temporal interval between precursor and test word, and by selectively eliminating either voicing information or spectral structure from the precursors, the present experiments show that the context effect is caused by the presence or absence of voicing in the precursor's final segment. The effect decreases with temporal separation but persists over several seconds. In addition, the "baseline" VOT boundary for isolated test words interspersed in a test sequence shifts depending on what precursor stimuli occur in the same sequence. The perception of VOT thus seems to be sensitive to both close and distant manifestations of laryngeal activity, always in an assimilative fashion, which suggests an integrative perceptual mechanism with a long time constant.

Nonlinear Mie scattering: electrostrictive coupling of light to droplet acoustic modes

Nonlinear Mie scattering at 532 nm was observed from 23-microm-diameter ethanol droplets excited by picosecond light pulses. Low-order optical modes (l = 2-4), normally hidden at low intensity, became visible as new peaks in elastic scattering spectra at 2 GW/cm(2). When higher-Q resonances were selectively excited, the scattered light showed an amplitude-modulated time dependence. The data are explained by electrostrictive generation of acoustic modes of the droplet by the incident radiation and subsequent coupling of the acoustic disturbance back onto the light field.