Training for prevention and management of chronic obstructive pulmonary disease among general practitioners: status quo and reflection / 中华全科医师杂志

Chronic obstructive pulmonary disease (COPD) is a preventable and treatable common chronic airway disease. As the gatekeeper of health care, general practitioners should play a key roles in prevention and management of COPD; however, the ability of COPD prevention and management is generally limited among general practitioners, so that the training for them is essential. At present there is no unified training program and standard for COPD prevention and management in China, the training contents and methods are various, and the training facilities and capacity are inadequate, particularly in grass-roots institutions, all these restrain the development of effective training. This articles reviews the status quo of COPD prevention and management training for general practitioners at home and abroad, and suggests to construct a network for chronic respiratory diseases management and a training system for primary care health workers to improve the prevention and management of COPD in China.

Mechanism of racanisodamine on alleviating radiation-induced lung injury in mice / 中华放射医学与防护杂志

Objective:To investigate the protective effect of racanisodamine on lung injury in mice exposed to irradiation.Methods:C57BL/6 mice were randomly divided into control group, racanisodamine group, 18 Gy irradiation group (model group) and racanisodamine combined with 18 Gy irradiation group (treatment group), with 5 mice in each group. The mice in the treatment group received racanisodamine (5 mg/kg) intraperitoneally 3 d before irradiation and contained the whole experiments. Then, single chest irradiation of 18 Gy X-rays was performed both in the model and treatment groups. The racanisodamine group and treatment group received racanisodamine intraperitoneally once a day until 6 weeks after irradiation. The mice were killed at 6 weeks after irradiation. The lung histopathology was observed by HE staining. Serum and bronchial alveolar lavage fluid (BALF) inflammatory cytokines such as TNF-α, IL-1β and IL-6 were determined by ELISA method. Cell senescence was detected by SA-β-Gal staining. The expressions of Nrf2, p-Nrf2 and p62 in lung tissue were performed by immunehistochemistry and Western blot assays.Results:Compared with the model group, the scores of HE staining were decreased ( t=8.66, P<0.01), the number of infiltrated inflammatory cells in BALF were decreased ( t=10.70, P<0.01), and protein concentration in BALF had lower levels ( t=6.75, P<0.01), the serum TNF-α, IL-1β and IL-6 were decreased significantly ( t=8.17, 4.58, 6.54, P<0.01), the activity of SA-β-gal was decreased, and the expressions of Nrf2, p-Nrf2 were enhanced ( t=6.42, 7.30, P<0.01), while the expression of p62 was reduced ( t=4.62, P<0.01) in the treatment group. Conclusions:Racanisodamine plays the protective effect of radiation-induced lung injury by alleviating inflammation associating with the activating of Nrf2-related pathway, which reversed radiation-induced cell senescence.

Preparation of mouse monoclonal antibodies against human adenovirus 55 Hexon (HAdV55 Hexon) protein / 细胞与分子免疫学杂志

Objective To prepare specific mouse monoclonal antibody (mAb) against human adenovirus type 55 Hexon protein (HAdV55 Hexon). Methods The Hexon genes of HAdV55, 3, 4, 7, 16 and 21 were chemically synthesized as templates for PCR amplification. The prokaryotic expression plasmids pET28a-HAdV55 Hexon and eukaryotic expression plasmids pCAGGS-HAdV3, 4, 7, 16, 21 and 55 Hexon were constructed respectively. The pET28a-HAdV55 Hexon plasmid was transformed into E. coli competent cell BL21 (DE3) and was induced by IPTG. After the purified inclusion body was denatured and renatured, Hexon55 protein was purified by tangential flow filtration system. pCAGGS-HAdV55 Hexon was used to immunize BALB/c mice by cupping, and HAdV55 Hexon protein was used to booster immunization. The anti-HAdV55 Hexon mAb was prepared by hybridoma technique and the titer and subclass were determined. The specificity of antibody was identified by Western blot using HEK293T cells transfected with pCAGGS-HAdV55 Hexon and by immunofluorescence assay (IFA) using BHK cells transfected with pCAGGS-HAdV55 Hexon. Both clones with high titer were selected, and the cross-reactivity of pCAGGS-HAdV3, 4, 7, 16, 21 and 55 Hexon transfected cells were analyzed by Western blot analysis and IFA. Results PET28a-HAdV55 Hexon and pCAGGS-HAdV55 Hexon, 3, 4, 7, 16 and 21 expression plasmids were successfully constructed. BL21 transformed with pET28a-HAdV55 Hexon was induced by IPTG. The HAdV55 Hexon protein was mainly expressed in the form of inclusion body. After denaturation and renaturation, the purified HAdV55 Hexon protein was obtained by ultrafiltration. Six hybridoma cell lines secreting HAdV55 Hexon mAb were obtained. The antibody subclass analysis showed that 2 strains were IgG2a subtypes and 4 strains were IgG2b. Two specific HAdV55 Hexon antibodies with high titer were obtained, and there was no cross-reactivity with HAdV3, 4, 7, 16, 21 Hexon. Conclusion The specific mice mAb against HAdV55 Hexon provides an experimental basis for establishing its antigen detection method.

Clinical value of narrow-band imaging endoscopy in children with esophageal polyps / 中华消化内镜杂志

To investigate the diagnostic value of narrow-band imaging (NBI) endoscopy for esophageal polyps in children. Microscopic morphology of various polyps in 35 children with esophageal polyps in Children's Hospital of Shanghai from January 2016 to June 2020 were observed under both traditional white light endoscopy and NBI endoscopy. The sensitivity and specificity of traditional white light endoscopy and NBI endoscopy were compared with the pathological results as the gold standard. A total of 70 esophageal polypoid lesions were found in 35 children, including 27 single polyps. Pathological results indicated that the majority of polyps were non-neoplastic polyps (52.9%, 37/70).The sensitivity of NBI endoscopy in the diagnosis of esophageal neoplastic polyps was significantly higher than that of white light endoscopy [93.9% (31/33) VS 90.9% (30/33), P < 0.001], and the specificity was also higher [89.2% (33/37) VS 78.4% (29/37), P=0.864]. By observing the microscopic structure of esophageal polyps, NBI endoscopy contributes to the clinical prediction of the pathological properties of polyps. Its sensitivity is superior to the white light endoscopy.

Determination of 17 elements in placenta by microwave digestion-inductively coupled plasma mass spectrometry / 预防医学

Objective@#To establish a microwave digestion-inductively coupled plasma mass spectrometry assay for simultaneous determination of multiple elements in placenta.@*Methods@#Fresh placental tissues were dried at 60 ℃ for 15 h and ground into power. Then, 0.3 g homogenized samples were digested in a microwave digestion system. The interference from mass spectrometry was removed using the kinetic energy discrimination model in the inductively coupled plasma mass spectrometry, and the baseline interference was removed by online internal standards. The contents of 17 elements were determined in placental specimens using the established microwave digestion -inductively coupled plasma mass spectrometry assay, including V, Ni, Co, Fe, Cr, Cu, Zn, Mn, As, Sn, Sb, Ba, Se, Cd, Pb, Hg and Tl.@*Results@#Good linearity was shown for V, Ni, Co, Cr, As, Se, Cd, Pb and Tl at 1 to 50 µg/L, Fe at 100 to 5 000 µg/L, Zn, Cu, Mn and Ba at 10 to 500 µg/L, Sn and Sb at 0.1 to 5 µg/L, and Hg at 0.2 to 2 µg/L, with all correlation coefficients of 0.999 8 and higher. The detection limits of these 17 elements ranged from 0.5 to 100 μg/kg, with relative standard deviations of 2.1% to 6.5%, and recovery rates of 83.3% to 110.0%. The determination results of 17 elements were all within the normal reference range defined in the certified reference materials of chicken (GBW10018). @*Conclusions@#The microwave digestion-inductively coupled plasma mass spectrometry established based on optimized pretreatments and mass spectrometry detection conditions, is feasible for simultaneous determination of multiple elements in placenta.

Modeling and Prediction of the 2019 Coronavirus Disease Spreading in China Incorporating Human Migration Data

This study integrates the daily intercity migration data with the classic Susceptible-Exposed-Infected-Removed (SEIR) model to construct a new model suitable for describing the dynamics of epidemic spreading of Coronavirus Disease 2019 (COVID-19) in China. Daily intercity migration data for 367 cities in China are collected from Baidu Migration, a mobile-app based human migration tracking data system. Historical data of infected, recovered and death cases from official source are used for model fitting. The set of model parameters obtained from best data fitting using a constrained nonlinear optimization procedure is used for estimation of the dynamics of epidemic spreading in the coming weeks. Our results show that the number of infections in most cities in China will peak between mid February to early March 2020, with about 0.8%, less than 0.1% and less than 0.01% of the population eventually infected in Wuhan, Hubei Province and the rest of China, respectively.

Circ_0068655 Promotes Cardiomyocyte Apoptosis via miR-498/ PAWR Axis

BACKGROUND@#The cardiomyocyte apoptosis is considered as one of major contributions to cardiac remodeling after myocardial infarction (MI). Numerous studies find that circular RNAs (circRNAs) play pivotal roles in a variety of biological functions. However, the role of circ_0068655 in MI and human induced pluripotent stem-derived cardiomyocytes (HCMs) remains unknown. @*METHODS@#The expression of circ_0068655, miR-498, and PRKC apoptosis WT1 regulator (PAWR) in human MI heart tissues and hypoxia subjected HCMs was evaluated with qRT-PCR and Western blot. The effects of circ_0068655 on hypoxia-induced apoptotic death and cell migration in HCMs were evaluated with qRT-PCR, cell viability, cell death ELISA (POD), and Caspase-3 activity assay, and Trans-well assay, respectively. Furthermore, luciferase assay, qRT-PCR, biotin-labeled miRNA pulldown assay, and Western blot were employed in the functional studies. @*RESULTS@#We found that the expression of circ_0068655 and PAWR was enhanced in MI patients and hypoxia subjected HCMs; by contrast, the expression of miR-498 decreased. Inhibited expression of circ_0068655 in HMCs counteracted hypoxia-induced apoptotic death and impaired cell migration, in sharp contrast to circ_0068655 knockdown. We identified that circ_0068655 sponged an endogenous miR-498 to sequester and inhibit its activity, leading to the increased PAWR expression. @*CONCLUSIONS@#Our findings reveal that the expression of circ_0068655 can promote cardiomyocyte apoptosis through the modulation of miR-498-PAWR axis in vitro, which highlights the diagnostic and therapeutic value of circ_0068655 in patients with MI.

Advances in the Application of Peripheral Central Venous Catheter Tip Positioning Technology / 中国医疗器械杂志

The best tip position of PICC is located in the inferior 1/3 of superior vena cava to the junction between superior vena cava and right atrium. Ensuring the best tip position of PICC is very important for the treatment of patients. In this paper, the applications of X-ray positioning, electrocardiograph, ultrasound, electrocardiograph Doppler ultrasound guidance, and electromagnetic navigation system in PICC tip positioning technology are reviewed. The future development of PICC tip positioning technology is prospected.

Circ_0068655 Promotes Cardiomyocyte Apoptosis via miR-498/ PAWR Axis

BACKGROUND@#The cardiomyocyte apoptosis is considered as one of major contributions to cardiac remodeling after myocardial infarction (MI). Numerous studies find that circular RNAs (circRNAs) play pivotal roles in a variety of biological functions. However, the role of circ_0068655 in MI and human induced pluripotent stem-derived cardiomyocytes (HCMs) remains unknown. @*METHODS@#The expression of circ_0068655, miR-498, and PRKC apoptosis WT1 regulator (PAWR) in human MI heart tissues and hypoxia subjected HCMs was evaluated with qRT-PCR and Western blot. The effects of circ_0068655 on hypoxia-induced apoptotic death and cell migration in HCMs were evaluated with qRT-PCR, cell viability, cell death ELISA (POD), and Caspase-3 activity assay, and Trans-well assay, respectively. Furthermore, luciferase assay, qRT-PCR, biotin-labeled miRNA pulldown assay, and Western blot were employed in the functional studies. @*RESULTS@#We found that the expression of circ_0068655 and PAWR was enhanced in MI patients and hypoxia subjected HCMs; by contrast, the expression of miR-498 decreased. Inhibited expression of circ_0068655 in HMCs counteracted hypoxia-induced apoptotic death and impaired cell migration, in sharp contrast to circ_0068655 knockdown. We identified that circ_0068655 sponged an endogenous miR-498 to sequester and inhibit its activity, leading to the increased PAWR expression. @*CONCLUSIONS@#Our findings reveal that the expression of circ_0068655 can promote cardiomyocyte apoptosis through the modulation of miR-498-PAWR axis in vitro, which highlights the diagnostic and therapeutic value of circ_0068655 in patients with MI.

Expert consensus on the establishment and maintenance of central vascular access under electrocardiography Doppler ultrasound guidance / 中国介入影像与治疗学

Central vascular access is an important tool for patients with clinically severe condition, tumor, and long-term need for intravenous infusion. The placement and indwelling of vascular access in the appropriate vessels and the correct position of the catheter tip can maintain long-term patency and reduce complications such as infection, thrombosis and catheter displacement, etc. The application of ultrasound Doppler combined with electrocardiography to guide the operation and maintenance of vascular access, instead of the traditional blind venipuncture and chest X-ray post-procedural location, is able to avoid radiation exposure damage to patients, especially pregnant women, newborns and children. The device of ultrasound Doppler combined with electrocardiography is called electrocardiography Doppler ultrasound guiding (EDUG), which has been widely used in clinical practice and accepted a new method of minimally invasive surgery, interventional treatment, emergency rescue and nursing clinical operation of vascular access in China. The experts from Cardiovascular Equipment Technical Committee of China Medical Equipment Association, China Interventional Medical Industry Technology Innovation Alliance Percutaneous Vascular Access Innovation Center, Interventional Medical Engineering and Biotechnology Committee on Interventional Physician of Chinese Medical Association discussed the expert consensus together, combined with the clinical practice and scientific questions, which would be a reference for clinical physicians and nurses.

Practice and consideration on teaching of military flying labor hygiene / 中华医学教育探索杂志

Military flying labor hygiene is a discipline that focuses on influences of special flight environment and labor condition on human body and related prevent measures,with the core of flight fatigue.Health information and technique training can help flight surgeons to enhance professional competency and improve the prevention and recovery of military flying fatigue.The course construction of teaching system in this study included survey of demand,arrangement of content,identification of strategy,determination of evaluation,and feedback of results.Meanwhile,the textbook compilation,cultivation of teaching team and construction of laboratory were also needed.After a 4-year practice,a formal teaching system has been established and its teaching effectiveness has basically fulfilled the professional requirement for flight surgeons.

Prehospital scales predict large vessel occlusion in patients with acute ischemic stroke: a comparison of 10 scales / 国际脑血管病杂志

Objective@#To compare the predictive value of 10 prehospital assessment scales for large vessel occlusion in patients with acute ischemic stroke.@*Methods@#From January 2016 to December 2018, patients with acute ischemic stroke within 24 h of onset admitted to the Department of Neurology, Nanfang Hospital, Southern Medical University were enrolled retrospectively. The scores of various scales were calculated based on clinical data, including the National Institutes of Health Stroke Scale (NIHSS), Los Angeles Motor Scale (LAMS), and 3-item stroke scale (3I- SS), Prehospital Acute Stroke Severity Scale (PASS), Ambulance Clinical Triage For Acute Stroke Treatment (ACT-FAST), and Stroke Vision, Aphasia, and Neglect Assessment Scales (VAN), etc. The predictive threshold of the NIHSS score was determined, and the receiver operating characteristic (ROC) curve and the area under the curve (AUC) were used to evaluate the effectiveness of various prehospital scales to predict large vessel occlusion.@*Results@#A total of 705 patients with acute ischemic stroke within 24 h of onset were enrolled, including 252 (35.7%) with large vessel occlusion. The best predictive cutoff value for judging large vessel occlusion by the NIHSS score was 9, sensitivity was 81.7%, specificity was 79.7%, positive likelihood ratio was 4.851, and negative likelihood ratio was 0.260. LAMS score ≥4 (sensitivity 88.1%, specificity 81.0%, positive likelihood ratio 4.640, and negative likelihood ratio 0.247), VAN positive (sensitivity 83.7%, specificity 82.3%, positive likelihood ratio 4.741, and negative likelihood ratio 0.198) and NIHSS score ≥9 were more accurate in identifying large vessel occlusion. The AUC values of the 8 quantitative scores were all > 0.7, and the AUC of LAMS was the largest (0.852, 95% confidence interval 0.825-0.878).@*Conclusions@#In patients with acute ischemic stroke within 24 h of onset, the NIHSS score ≥9 can be used as the best cutoff value for predicting large vessel occlusion events. LAMS, VAN, and NIHSS scales are more accurate in predicting large vessel occlusion. The predictive power of the 8 quantitative scales is higher, and the AUC of LAMS is the largest, which can be used for clinical prediction of large vessel occlusion in patients with acute ischemic stroke.

Practice and consideration on teaching of military flying labor hygiene / 中华医学教育探索杂志

Military flying labor hygiene is a discipline that focuses on influences of special flight environment and labor condition on human body and related prevent measures, with the core of flight fatigue. Health information and technique training can help flight surgeons to enhance professional competency and improve the prevention and recovery of military flying fatigue. The course construction of teaching system in this study included survey of demand, arrangement of content, identification of strategy, determination of evaluation, and feedback of results. Meanwhile, the textbook compilation, cultivation of teaching team and construction of laboratory were also needed. After a 4-year practice, a formal teaching system has been established and its teaching effectiveness has basically fulfilled the professional requirement for flight surgeons.

Major routes for orphan drugs to be incorporated into the reimbursement system of UK and the enlightenment to China / 中国药科大学学报

@#In order to provide enlightening experience for the establishment of reasonable and diversified orphan drugs into the reimbursement system in China, the official websites of the National Institute for Health and Care Excellence(NICE)and the National Health Service(NHS)in the UK were inspected, collecting and summarizing the relevant documents, on the inclusion of orphan drugs into the reimbursement system. Relevant literatures were analyzed with theoretical studies on the accessibility of medicines for patients with rare diseases. In the NHS system, the inclusion of orphan drugs into the reimbursement system in the UK can be achieved mainly through seven routes, with three routes that are evaluated by NICE(MTA, STA and HST)and four are directly managed by the NHS(specialized commissioning, CDF, IFRs, CtE). Through the analysis of the inclusion of orphan drugs into the reimbursement system and the various problems in the UK, we have found some enlightening experience for the establishment of the reimbursement system for orphan drugs in China.

Progress in Research Drug Eluting Stents Drug-looding and Drug Release Kinetics / 中国医疗器械杂志

Drug eluting stents are one of the main devices of coronary intervention, which play a therapeutic role through the combination of medical devices. Drug is an important part of the drug eluting stents. The loading method, the type of carrier, drug and carrier interaction and the preparation process of the drug directly affect the drugs release kinetics characteristics of the device and the final treatment. According to the characteristics of the drug coating, drug coated stents can be divided into non-degradable polymers drug coated stents, biodegradable polymers drug coated stents and polymer-free drug eluting stents. This article discussed the stent coating process and drug release kinetics of the three types of drug eluting stent.

Advances in Implantable Medical Device Battery / 中国医疗器械杂志

In recent years, active implantable medical devices become a hot spot of the medical device industry. There are still many problems in terms of reliability, capacity and life expectancy because of the subject to material and technical constraints. This review summarizes the development history and current status of the batteries used in active implantable medical devices, and describes the development and problems of zinc-mercury batteries and lithium batteries. The flexible batteries and bio-energy battery and other new battery technology are also expounded. The future of active implanted medical device battery is bound to miniaturization, flexibility, rechargeable direction.

Development and Application of Fiber-optic Pressure Sensor in Medical Field / 中国医疗器械杂志

pressure monitoring is important for monitoring of organ or tissue lesions and real-time analysis of intraoperative conditions. Compared with the traditional electromechanical pressure sensor, the optical fiber pressure sensor has the advantages of small size, high sensitivity, high safety and strong ability of resisting electromagnetic interference. It has been widely applied in the medical field. This thesis reviews the development of optical fiber pressure sensors and the application of pressure monitoring in the medical field. It emphatically analyses the monitoring of the optical fiber pressure sensor in cardiovascular and blood, intracranial, airway, gastrointestinal tract and other tissues or organs. Analysis shows that the favorable result of monitor can be got using optical fiber pressure sensor in different tissues or organs.

Changes of MMP9 and TIMP 1 Expressions and Activity in the Carotid Artery of 4 wk Hindlimb Unweighted Rat / 现代生物医学进展

Objective:To investigate the changes of gene or protein expression and activity of matrix metalloprotein9 (MMP9) and tissue inhibitor ofmetalloproteinasel (TIMP1) in the carotid artery (CA) of 4 wk hindlimb unweighted rat.Methods:A 4 weeks(wk) hindlimb unweighted (HU) rat model was used to simulate the effect of weightlessness on the cardiovascular system.Transmission electron microscopy was used to detect the content of ECM.Reverse transcriptase polymerase chain reaction(RT-PCR) was conducted to measure the mRNA content MMP and TIMP1.Immunohistochemistry and Western blot technique were used to measure the protein abundance.Gelatin zymography was carried out to detect the activity of MMP9.Results:Compared to the control group (CON),the area of ECM was enhanced (P＜0.05) and the content of collage fiber was increased (P＜0.05) in the CA of HU rats;moreover,HU did not affect the mRNA expression of MMP9,but significantly reduced the protein content (P＜0.05) or enzymatic activity (P＜0.05).Accordingly,the mRNA or protein expression of TIMP1 in the CA was significantly increased by HU (P＜0.05).Conclusion:Simulated weightlessness caused imbalance between MMP and TIMP1 expression,which might contribute to the ECM aggregation and stiffness of CA.

Complications and its management of refractory esophageal stric-tures treating with nitinol self-expandable metal stent in children / 中国内镜杂志

Objective To investigate the complications and management of nitinol self-expandable metal stent (cSEMS) in treatment of refractory esophageal strictures in children. Methods The clinical data were reviewed for 9 pediatric patients with refractory benign esophageal disorders from May 2009 to December 2016, specially designed cSEMS were applied to them, data about effects and complications were collected during regular follow-ups. Results Successful cSEMS placement was performed in 9 children, the symptom of dysphagia was obviously alleviated after implantation, all patients underwent vomiting and chest pain 1~7 days after operation; 1 case could not put up with the pain, so the stent had to be removed in 36 hours after implantation; 2 cases developed a recurrent stricture within 3 months after stent removal, growth of mild granulation tissue was found in 1 case; In the case with esophageal fistulas, migration and poor adherence to the esophagus was occurred in 3 days after implantation, then a new designed cSEMS with bigger proximal tip was planted in the same place 1 week later, 2 months after stent removed, fistula was healed. Conclusion Placement of cSEMS is safe and effective in treating pediatric patients with refractory esophageal stricture. However, complications associated with stent placement should not be ignored, individually designed stent and timely management of the complications are quite important in order to enhance clinical efficacy.

Diagnostic value of CEA, CA153, TPS, Fer and CYFRA21-1 in postoperative metastasis of breast cancer / 实用医学杂志

Objective To explore the diagnostic value of tumor markers of CEA,CA153,TPS,Fer and CYFRA21-1 level in postoperative metastasis of breast cancer.Methods After 3-year follow-up for 578 patients with primary breast cancer from 2012 to 2014,we chose 42 patients with metastasis as metastasis group,and another 42 cases without as non-metastasis group.Level of CEA,CA153,TPS,Fer and CYFRA21-1 was detected using chemiluminescence and the difference of CEA,CA153,TPS,Fer and CYFRA21-1 level in 2 groups was compared.Pearson correlation test analysis and ROC curve test were performed for data analysis.Results Serum CEA,CA153,TPS,Fer and CYFRA21-1 levelq6.11 ± 1.87)ng/mL,(26.97 ± 9.52) U/mL,(155.95 ± 22.03)U/L,(173.08 ± 19.87)ng/mL and (18.98 ± 7.33)ng/mL respectively increased in metastasis group when compared with those in non-metastasis group (5.33 ± 1.85)ng/mL,(23.34 ± 8.30)U/mL、(133.22 ± 19.09)U/L,(142.29 ± 22.59) ng/mL and (6.76 ± 1.59)ng/mLrespectively and the change of TPS,Fer and CYFRA21-1 was more obvious and the difference was statistically significant (P ＜ 0.05).There was no significant correlation among serum TPS,Fer and CYFRA21-lin metastasis group.The area under ROC curve of CYFRA21-1 was 0.903,followed by Fer (0.849) and TPS (0.791) and in the diagnosis of metastasis of breast cancer,CYFRA21-1 has great diagnostic value.Conclusions The increase of serum TPS,Fer and CYFRA21-1 level is closely associated with postoperative metastasis of breast cancer and CYFRA21-1 has great diagnostic value for monitoring postoperative metastasis of breast cancer.