[Participation rate and detection of colorectal neoplasms based on multi-round fecal immunochemical testing for colorectal cancer screening in the Chinese population]

Objective: To evaluate the participation rate and detection of colorectal neoplasms based on annual fecal immunochemical testing (FIT) for three consecutive years in a population-based colorectal cancer screening program in China. Methods: Based on a population-based colorectal cancer screening program conducted from May 2018 to May 2021 in 6 centers in China, 7 793 eligible participants aged 50-74 were included and offered free FIT and colonoscopy (for those who were FIT-positive on initial screening). At baseline, all participants were invited to receive FIT. In subsequent screening rounds, only FIT-positive participants who did not undergo colonoscopy or FIT-negative participants were invited to have repeated FIT screening. FIT-positive participants were recommended to undertake colonoscopy and pathological examination (if abnormalities were found during colonoscopy). An overall of three rounds of annual FIT screening were conducted. The primary outcomes of the study were the participation rate of FIT screening, the compliance rate of colonoscopy for FIT-positive participants, and the detection rate of colorectal neoplasms. Results: Among the 7 793 participants included in this study, 3 310 (42.5%) were male, with age of (60.50±6.49) years. The overall participation rates for the first, second and third round of FIT screening were 94.0%(7 327/7 793), 86.8% (6 048/6 968) and 91.3% (6 113/6 693), respectively. Overall, 7 742 out of 7 793 participants (99.3%) attended at least one round of screening, and 5 163 out of 7 793 participants (66.3%) attended all three rounds of screening. The positivity rate was significantly higher in the first (14.6%, 1 071/7 327) round compared with the second (5.6%, 3 41/6 048) and third (5.5%, 3 39/6 113) screening rounds (P<0.001). The overall compliance rates of colonoscopy examination among FIT-positive subjects were over 70% in three rounds, which were 76.3% (817/1 071), 75.7% (258/341) and 71.7% (243/339), respectively. In a multivariate logistic regression model considering factors including sex, education background, smoking, alcohol drinking, previous colonoscopy examination, colonic polyp history and family history of colorectal cancer among first-degree relatives, gender and smoking status were related factors affecting the participation rate of FIT screening, with higher rate in males and non-smokers. In addition, logistic regression analysis also found that age was negatively correlated with the compliance rate of colonoscopy in FIT positive patients. The detection rate of advanced tumors (colorectal cancer + advanced adenoma) declined from the first round to subsequent rounds [1st round: 1.15% (90/7 793); 2nd round: 0.57% (40/6 968); and 3rd round: 0.58% (39/6 693)], however, the positive predictive value for advanced neoplasms increased round by round, and was 11.02% in the first screening round, 15.50% in the second screening round, and 16.05 % in the third screening round. In each screening round, the detection rate for advanced neoplasms was higher in men than that in women, and increased with age. Conclusions: Annual repeated FIT screening has high acceptance and satisfying detection rates in the Chinese population. To optimize and improve the effectiveness of colorectal cancer screening, multi-round repeated FIT screening should be implemented while ensuring high participation rates.

[Value of fecal immunochemical test in colorectal cancer screening]

Screening and early diagnosis and treatment have been proven effective in reducing the incidence and mortality of colorectal cancer. Colonoscopy combined with pathological examination is the gold standard for colorectal cancer screening. However, due to the invasiveness, high cost and the need for professional endoscopists of colonoscopy, it is not feasible to directly use this method for mass population screening. Fecal immunochemical test (FIT) is one of the screening techniques recommended by authoritative international guidelines for colorectal cancer screening, and has been widely used in population-based colorectal cancer screening programs in countries around the world. This paper elaborates on the value of FIT in colorectal cancer screening from different aspects, such as the technical principles, the screening efficiency, the screening strategies, and the population effects and benefits. Additionally, it describes the current situation of colorectal cancer screening in China and summarizes the challenges faced in colorectal cancer screening in order to optimize the FIT-based colorectal cancer screening strategies in the population and provide theoretical reference for effective colorectal cancer screening.

[New progress in the diagnosis and treatment of pet allergens and related allergic diseases]

Pet allergies are the type Ⅰ allergic reaction stimulated by allergens in pet dander, hair, and saliva and urine. Atopic individuals with pet allergies have mucosal and respiratory symptoms and casually severe anaphylaxis. Recently, the increasing presence of household pets in China has contributed to an increase in the prevalence of allergies to pets. Moreover, pet allergen sensitization is one of the critical risk factors for developing other allergic diseases, posing a major health problem. This article discussed the epidemiology, allergenic components, clinical features, diagnosis and management, and prevention of pet allergies, providing advice for prevention and treatment.

[Regulatory effects of the Nocardia rubra cell wall skeleton on the biological function of human neutrophils]

Objective: To investigate the regulatory effects and mechanism of Nocardia rubra cell wall skeleton (Nr-CWS) on the biological function of human neutrophils. Methods: The experimental research method was used. Fifteen healthy adult volunteers (7 males and 8 females, aged 24 to 45 years) were recruited from Suzhou Physical Examination Center for physical examination from May to October 2022, the peripheral venous blood was collected, and neutrophils were extracted by immunomagnetic bead sorting. The cells were divided into normal control group without any treatment, Nr-CWS alone group treated with Nr-CWS of final mass concentration 60 ng/mL alone, endotoxin/lipopolysaccharide (LPS) alone group stimulated with LPS of final mass concentration 1 μg/mL alone, and LPS+Nr-CWS group stimulated with LPS first and then treated with Nr-CWS as before. After 1 h of culture, the chemotaxis distance, chemotactic cell percentage, chemotactic index, maximum chemotactic speed, and chemotactic function score of neutrophils were detected using the modified agarose chemotactic model; the proportion and fluorescence intensity of phagocytosis cells, the level of reactive oxygen species (ROS), the protein expression levels of granular protein CD35, CD66b, and CD63, and the concentrations of inflammatory cytokines of interleukin 2 (IL-2), IL-4, IL-6, IL-10, IL-17A, tumor necrosis factor alpha (TNF-α), and interferon-γ in cell culture supernatant were detected by flow cytometry. The number of samples in each group in the above experiments was 15. Data were statistically analyzed with analysis of variance for factorial design and independent sample t test. Results: After 1 h of culture, the chemotactic function score of cells in normal control group, Nr-CWS alone group, LPS alone group, and LPS+Nr-CWS group were 15.0, 14.5±0.5, 1.5±0.5, 12.0±1.5, respectively. Compared with those in normal control group, the chemotaxis distance, chemotactic cell percentage, chemotactic index, maximum chemotactic speed, and chemotactic function score of cells were significantly decreased in LPS alone group and LPS+Nr-CWS group (with t values of 18.36, 18.88, 54.28, 18.36, 46.77, 10.58, 14.74, 6.84, 10.58, and 4.24, respectively, P<0.05); compared with those in LPS alone group, the five chemotactic function indexes as above in LPS+Nr-CWS group were significantly increased (with t values of 11.47, 14.65, 11.62, 11.47, and 13.75, respectively, P<0.05). After 1 h of culture, compared with those in normal control group, the proportion and fluorescence intensity of phagocytosis cells were significantly increased in Nr-CWS alone group (with t values of 6.86 and 6.73, respectively, P<0.05), and the above two indexes were significantly decreased in LPS alone group (with t values of 7.35 and 22.72, respectively, P<0.05) and LPS+Nr-CWS group (with t values of 21.37 and 13.10, respectively, P<0.05). After 1 h of culture, compared with that in normal control group, the level of ROS of cells in LPS alone group was significantly increased (t=6.64, P<0.05); compared with that in LPS alone group, the level of ROS of cells in LPS+Nr-CWS group was significantly decreased (t=5.46, P<0.05). After 1 h of culture, compared with those in normal control group, the protein expressions of CD35, CD66b, and CD63 of cells were significantly increased in LPS alone group and LPS+Nr-CWS group (with t values of 16.75, 17.45, 10.82, 5.70, 19.35, and 15.37, respectively, P<0.05); compared with those in LPS alone group, the protein expressions of CD35, CD66b, and CD63 of cells were significantly decreased in LPS+Nr-CWS group (with t values of 4.92, 5.72, and 3.18, respectively, P<0.05). After 1 h of culture, compared with those in normal control group, the concentrations of IL-2, IL-4, IL-6, IL-10, IL-17A, TNF-α, and interferon-γ in cell culture supernatant were significantly increased in LPS alone group (with t values of 22.10, 9.50, 7.21, 10.22, 24.88, 8.43, and 47.48, respectively, P<0.05), and the concentrations of IL-6, IL-10, IL-17A, TNF-α, and interferon-γ in cell culture supernatant were significantly increased in LPS+Nr-CWS group (with t values of 4.68, 5.12, 8.02, 5.58, and 7.13, respectively, P<0.05); compared with those in LPS alone group, the concentrations of IL-2, IL-4, IL-6, IL-10, IL-17A, TNF-α, and interferon-γ in cell culture supernatant were significantly decreased in LPS+Nr-CWS group (with t values of 5.39, 2.83, 5.79, 2.90, 5.87, 4.88, and 39.64, respectively, P<0.05). Conclusions: Nr-CWS can enhance the phagocytosis ability of neutrophils in normal condition and improve the chemotactic function, ROS level, degranulation protein level, and inflammatory factor level of human neutrophils in infectious condition. Nr-CWS can enhance the anti-infection ability of human neutrophils by regulating its biological behavior in innate immunity.

[Analysis of clinicopathological features of 18 cases of hepatic angiosarcoma]

Objective: To investigate the clinicopathological features, treatment, and prognosis of hepatic angiosarcoma. Methods: Clinicopathological data and prognostic conditions of 18 cases with hepatic angiosarcoma were collected retrospectively. The recurrence-free survival rate and overall survival rate were calculated by the Kaplan-Meier method. A Cox regression analysis was used to explore the survival-related risk factors. Results: There were 12 male and 6 female patients, with an average age of 57 (37 ~ 70) years. The tumor's average diameter was 8.40 (2.00 ~ 18.00) cm. Seven cases had multiple tumors, while two cases had large vessel tumor thrombuses. Microscopically, the tumor tissues were irregularly anastomosed, with vascular lacunar or solid bundle-like weaving, and the tissue morphology mimicked capillary hemangioma, cavernous hemangioma, or angioepithelioma, while tumor cells were spindle-shaped or epithelioid, lined with hobnails in the lumen, or formed papillary structures in the lumen. The proportion of highly, moderately, and poorly differentiated tumors was 4:8:6, with six cases having clear tumor boundaries, eight having microvascular tumor thrombi, and sixteen having blood lake formation. Different levels of expression of CD31, CD34, erythroblast transformation-specific related genes, and Fli-1 markers were demonstrated in all of the cases. Four cases had a P53 mutation, and six cases had Ki-67 > 10%. During the follow-up period of 0.23-114.20 months, the five-year recurrence-free survival rate and overall survival rate were 16.7% and 37.2%, respectively. Cox regression multivariate analysis showed that preoperative symptoms and multiple tumors were significant risk factors for recurrence-free survival, while preoperative symptoms and Ki-67 > 10% were significant risk factors for overall survival. Conclusion: Hepatic angiosarcoma is a rare hepatic mesenchymal tumor with high malignancy and a poor prognosis. Pathological morphology and immunohistochemical marker combinations are needed for a definite diagnosis. However, the complexity of angiosarcomas' histological and cytological conformations and the overlap of pathological features with benign vascular tumors, sarcomas, and carcinomas pose difficulties in the differential diagnosis. Thus, the only effective ways to prolong survival are early detection and radical surgical resection.

[Research on applying genetic and environmental risk score in risk-adapted colorectal cancer screening]

Objective: To evaluate the effectiveness of a risk-adapted colorectal cancer screening strategy constructed utilizing genetic and environmental risk score (ERS). Methods: A polygenic risk score (PRS) was constructed based on 20 previously published single nucleotide polymorphisms for colorectal cancer in East Asian populations, using 2 160 samples with MassARRAY test results from a multicenter randomized controlled trial of colorectal cancer screening in China. The ERS was calculated using the Asia-Pacific Colorectal Screening Score system. Logistic regression was used to analyze the association between PRS alone and PRS combined with ERS and colorectal neoplasms risk, respectively. We also designed a risk-adapted screening strategy based on PRS and ERS (high-risk participants undergo a single colonoscopy, low-risk participants undergo an annual fecal immunochemical test, and those with positive results undergo further diagnostic colonoscopy) and compared its effectiveness with the all-acceptance colonoscopy strategy. Results: The high PRS group had a 26% increased risk of colorectal neoplasms compared with the low PRS group (OR=1.26, 95%CI: 1.03-1.54, P=0.026). Participants with the highest PRS and ERS were 3.03 times more likely to develop advanced colorectal neoplasms than those with the lowest score (95%CI: 1.87-4.90, P<0.001). As the risk-adapted screening simulation reached the third round, the detection rate of the PRS combined with ERS strategy was not statistically different from the all-acceptance colonoscopy strategy (8.79% vs. 10.46%, P=0.075) and had a higher positive predictive value (14.11% vs. 10.46%, P<0.001) and lower number of colonoscopies per advanced neoplasms detected (7.1 vs. 9.6, P<0.001). Conclusion: The risk-adapted screening strategy combining PRS and ERS helps achieve population risk stratification and better effectiveness than the traditional colonoscopy-based screening strategy.

[Associations of all-cause mortality with admission blood pressure variability during multiple hospitalizations in acute decompensated heart failure]

Objective: To investigate whether admission blood pressure (BP) variability during multiple hospitalizations is associated with all-cause mortality independent of baseline BP in acute decompensated heart failure (ADHF). Methods: Patients with ADHF admitted to the Department of Cardiology, The First Affiliated Hospital of Sun Yat-Sen University from September 2013 to December 2017 were retrospectively enrolled. The risk of all-cause mortality associated with indices of BP variability, including mean admission BPs, standard deviation of BP and coefficient of variation of BP during multiple hospitalizations was assessed, using Cox regression model. Results: A total of 1 006 ADHF patients (mean aged (69.3±13.5) years; 411 (40.8%) female; 670 (66.6%) with preserved ejection fraction) were enrolled. During a median follow-up of 1.54 years, 47.0% of patients died. In all ADHF patients, after adjusting for confounding factors, for every 1-standard deviation (SD) increase in SD and coefficient of variation (CV) of systolic BP, the risk of all-cause mortality increased by 10% and 11%, respectively (SD: HR, 1.10, 95%CI, 1.01-1.21, P=0.029, CV: HR, 1.11, 95%CI, 1.02-1.21, P=0.017); for every 1-SD increase in the mean of diastolic BP, the risk of all cause mortality decreased by 25% (HR, 0.75; 95%CI, 0.65-0.87; P<0.001). In ADHF patients with preserved ejection fraction, after accounted for potential confounders, higher SD and CV of admitted systolic and diastolic BP were significantly associated with higher risk of all-cause mortality, regardless of whether confounding factors were adjusted (P≤0.049); After adjusting for confounding factors, the risk of all-cause mortality increased by 18% and 19% for every 1-SD increase in SD and CV of systolic BP, while the risk of all-cause mortality increased by 11% and 15% for every 1-SD increase in SD and CV of diastolic BP. In ADHF patients with reduced ejection fraction, after adjusting for confounding factors, the higher the mean admission systolic BP during multiple hospitalizations, the lower the risk of total mortality (HR, 0.68; 95%CI, 0.47-1.00; P=0.049). Conclusions: In patients with ADHF, independent of baseline BP, BP variability during multiple hospitalizations was strong predictor of all-cause mortality.

[Characteristics of plasma Epstein-Barr virus DNA in children with primary infection]

Objective: To explore the characteristics of plasma Epstein-Barr virus (EBV) DNA in primary infection in pediatric cases. Methods: The laboratory and clinical data of 571 children diagnosed with EBV primary infection in Children's Hospital of Fudan University during September 1^st, 2017 to September 30^th, 2018 were retrospectively analyzed. According to the results of plasma EBV DNA, they were divided into positive group and negative group. According to the EBV DNA, they were devided into high plasma virol load group and low plasma virol load group. The Chi-square test, Wilcoxon rank sum test were used to compare the differences between groups. Results: Among the 571 children with EBV primary infection, 334 were males and 237 were females. The age of first diagnosis was 3.8 (2.2, 5.7) years. There were 255 cases in positive group and 316 cases in negative group. The percentage of cases with fever,hepatomegaly and (or) splenomegaly, elevated transaminase in the positive group were higher than those in the negative group (235 cases (92.2%) vs. 255 cases (80.7%), χ²=15.22, P<0.001; 169 cases (66.3%) vs. 85 cases (26.9%), χ²=96.80, P<0.001; and 144 cases (56.5%) vs. 120 cases (38.0%), χ²=18.27, P<0.001; respectively).In the positive group, 70 cases were followed up for 46 (27, 106) days, 68 cases (97.1%) turned negative within 28 days, with the exception of 2 cases (2.9%) developed chronic active EBV infection by follow-up revision.There were 218 cases in high plasma viral DNA copies group and 37 cases in low copies group. More cases presented with elevated transaminases in the high plasma viral DNA copies group than those in the low group (75.7% (28/37) vs. 56.0%(116/207), χ²=5.00, P=0.025).Both the positive rate of EBV DNA in peripheral blood leukocytes (84.2% (266/316) vs. 44.7% (255/571), χ²=76.26, P<0.001) and the copies of EBV DNA (7.0×10⁷ (1.3×10⁷, 3.0×10⁸) vs. 3.1×10⁶ (1.6×10⁶, 6.1×10⁶) copies /L, Z=15.23, P<0.001) were higher than that of plasma. Conclusions: In immunocompetent pediatric cases diagnosed as EBV primary infection, cases with positive plasma EBV DNA were prone to have fever, hepatomegaly and (or) splenomegaly, and elevated transaminase than those with negative plasma viral DNA. The plasma EBV DNA usually turns negative within 28 days after initial diagnosis.Most cases with high viral load in plasma showed elevated aminotransferase.

[Advance in pathogenesis of oligodendrocytes-associated autism spectrum disorder]

Autism spectrum disorder (ASD) is a serious neurodevelopmental impairment of children. Because of its difficulty of early diagnosis, length of disease course, irreversible injury and slim chance of curability, it brings heavy burdens to patients, their families and the whole society. Recent studies have shown that the pathogenic mechanism of ASD is closely related to the abnormal myelination caused by the imbalance of differentiation, proliferation and apoptosis of oligodendroglial lineage cells. This article will review on the role of oligodendroglial lineage cells in myelination and the mechanisms of ASD caused by improper differentiation, proliferation and apoptosis of oligodendroglial lineage cells, according to advanced researches. Oligodendrocytes play vital roles in neurodevelopment, and the defect in these cells has been recognized as one of the key pathogenic mechanisms leading to ASD. Elucidating the effects and disciplines which oligodendrocytes exert on the occurrence and development of ASD would provide guidance for precise prevention and control of neurodevelopmental disorders such as ASD.

[On the quotation of Sun Simiao's literature in the book of Bencao Tujing]

There are 18 original texts of Sun Simiao's literature quoted in the book of Bencao Tujing (, Illustration Classics for Materia Medica) edited by Su Song in the Northern Song Dynasty, involving Qianjin Yao Fang (, Invaluable Prescriptions), Qianjin Yi Fang (, Supplement to Invaluable Prescriptions) and Qianjin Yueling () . They are the versions of the Northern Song Dynasty or earlier versions, which have high collation value and collection value. The Qianjin Yao Fang quoted in the book of Bencao Tujing has different versions with the current version of Qianjin Yao Fang and the ancient version of Sun Zhenren Qianjin Fang (, Immortal Sun's Invaluable Prescriptions) . Some of these varieties are caused by Su Song's collation, while others are caused by different versions. According to the former, the latter can be corrected and supplemented. Qianjin Yi Fang quoted in Bencao Tujing is earlier than the edition in Dade period of Yuan Dynasty. According to the former, the latter can be corrected. The book of Qianjin Yueling edited by Sun Simiao has been lost. Part of the contents of the book are included in Euibangyoochui (, Classified Assemblage of Medical Prescriptions) published in Korea. Some scholars have compiled and copied the book accordingly. The texts of Qianjin Yueling quoted in the book of Bencao Tujing can be used to correct the mistakes of the lost edition of Qianjin Yueling and make up for its incompleteness.

Application of Artificial Intelligence Automatic Diatom Identification System in Practical Cases

Abstract

Objective To discuss the application of artificial intelligence automatic diatom identification system in practical cases, to provide reference for quantitative diatom analysis using the system and to validate the deep learning model incorporated into the system. Methods Organs from 10 corpses in water were collected and digested with diatom nitric acid; then the smears were digitally scanned using a digital slide scanner and the diatoms were tested qualitatively and quantitatively by artificial intelligence automatic diatom identification system. Results The area under the curve （AUC） of the receiver operator characteristic （ROC） curve of the deep learning model incorporated into the artificial intelligence automatic diatom identification system, reached 98.22% and the precision of diatom identification reached 92.45%. Conclusion The artificial intelligence automatic diatom identification system is able to automatically identify diatoms, and can be used as an auxiliary tool in diatom testing in practical cases, to provide reference to drowning diagnosis.

Relationship between Postmortem Interval and FTIR Spectroscopy Changes of the Rat Skin

Abstract

Objective To infer postmortem interval （PMI） based on spectral changes of the dorsal skin of rats within 15 days postmortem using Fourier transform infrared （FTIR） spectroscopy. Methods The rats were sacrificed by cervical dislocation after anesthesia, and then placed at 25 ℃ and relative humidity of 50%. The FTIR spectral data collected from the dorsal skin at PMI points were modeled with machine learning technique. Results There was no significant difference of absorption peak location among all the PMI groups but their peak intensities changed as a function of PMIs. The model for PMI estimation was constructed using partial least squares （PLS） regression, reaching a R² of 0.92 and a root mean square error （RMSE） of 1.30 d. As shown in variable importance for projection （VIP）, four spectral bands including 1 760-1 700 cm^-1, 1 660-1 640 cm^-1, 1 580-1 540 cm^-1 and 1 460-1 420 cm^-1 were determined as important contributions to model prediction. Conclusion Application of the FTIR technique to detect postmortem spectral changes of the rat skin provides a novel proposal for PMI estimation.

The use of a single ammonium acidic salt towards simple green co-precipitation synthesis for Mn4+-activated fluorides

Simply using acidic salt NH₄HF₂ contributes to the green co-precipitation synthesis of Mn⁴⁺-doped fluorides for W-LED applications.

Population dynamics of Echinops gmelinii Turcz. at different successional stages of biological soil crusts in a temperate desert in China

The effects of biological soil crusts (BSC) on vascular plant growth can be positive, neutral or negative, and little information is available on the impacts of different BSC successional stages on vascular plant population dynamics. We analysed seedling emergence, survival, plant growth and reproduction in response to different BSC successional stages (i.e. habitats: bare soil, cyanobacteria, lichen and moss crusts) in natural populations of Echinops gmelinii Turcz. in the Tengger Desert of northwest China. The winter annual E. gmelinii is a dominant pioneer herb after sand stabilisation. During the early stages of BSC succession, the studied populations of E. gmelinii were characterised by high density, plant growth and fecundity. As the BSC succession proceeded beyond moss crusts, the fecundity decreased sharply, which limited seedling recruitment. Differences in seedling survival among the successional stages were not evident, indicating that BSC have little effect on survival in arid desert regions. Moreover, E. gmelinii biomass allocation exhibited low plasticity, and only reproductive allocation was sensitive to the various habitats. Our results further suggest that the negative effects of BSC succession on population dynamics are primarily driven by increasing topsoil water-holding capacity and decreasing rain water infiltration into deeper soil. We conclude that BSC succession drives population dynamics of E. gmelinii, primarily via its effect on soil moisture. The primary cause for E. gmelinii population decline during the moss-dominated stage of BSC succession is decreased fecundity of individual plants, with declining seed mass possibly reducing the success of seedling establishment.

[Dream-hinting the prescriptions verified: new changes of prescriptions imparted by immortals in Song Dynasty and their cultural value of medicine]

Prescription imparted by immortals is a unique type of medical prescription. Its narrative mode changed in Song Dynasty. The mode changed from non-narrative dream and lacking of plot to integration of religious dream stories and folk prescriptions, thus it had dual functions: spreading medicine and doing missionary work. This new change first appeared in the notes of the Song Dynasty, and then entered the medical books of the Song Dynasty. Taking Hong Mai's Yi Jian Zhi(, The Records of Yi Jian) as an example, by analyzing 11 prescriptions imparted by immortals in dreams, it was found that their prescriptions conformed to pharmacology and were cited by subsequent medical books. The intentions behind the divine plot of god's presence in dreams, were to emphasize the sanctity of the source of prescriptions and the magical efficacy. Some of them were first recorded in notes of the Song Dynasty, and their cultural value of medicine should be objectively evaluated in the history of Chinese medicine.

[Effect of leader-member exchange on nurses'sense of calling in workplace]

Objective: To investigate the effect of leader-member exchange on nurses'sense of calling in workplace based on self-determination theory. Methods: A total of 381 nurses were randomly selected from five tertiary general hospitals in Zhejiang province, China from October to December, 2016. They were subjected to a survey using the Leader-Member Exchange Scale, Job Autonomy Scale, Core Self-Evaluation Scale, and Calling Scale. The mediating effect was used to test the procedures and the data were subjected to hierarchical regression analysis. Results: The leader-member exchange was positively correlated with job autonomy, core self-evaluation, and sense of calling (r=0.471, P<0.001; r=0.373, P<0.001; r=0.475, P<0.001) ; the leader-member exchange had a positive predictive effect on job autonomy and sense of calling (β= 0.47, P<0.001; β=0.48, P<0.001) ; the job autonomy had a partial mediating effect on the relationship between leader-member exchange and sense of calling (F=66.50, P<0.001) ; the core self-evaluation negatively adjusted the positive relationship between leader-member exchange and job autonomy (F=27.81, P<0.001) . Conclusion: High-quality leader-member exchange enhances the sense of calling by improving staffs' job autonomy and the core self-evaluation reduces the positive relationship between leader-member exchange and job autonomy.

[Olfactory functional magnetic resonance imaging in patients with mild cognitive impairment]

Objective: To analyze the activation of brain regions associated with olfactory in patients with mild cognitive impairment (MCI) by olfactory functional magnetic resonance imaging (fMRI). Methods: Twenty six patients with MCI were compared with twenty six controls in the dementia center of Tianjin HuanHu hospital in terms of olfactory function T&T testing, the differences between the activation of the whole brain and region of interest associated with olfactory (bilateral primary olfactory cortex(POC), bilateral hippocampus, bilateral orbital frontal gyrus) by olfactory stimulator using event correlation design for olfactory fMRI scanning. To analyze the correlation between the number of activator in POC and the threshold of olfactory discriminate as well as the severity of cognitive impairment.SPSS 19.0 software was used for the statistical analysis. Results: T&T olfactory testing revealed that MCI patients had higher scores than controls (3.57±1.29 (x±s) vs 1.02±0.35, t=4.372, P<0.05). The activation range of whole brain in MCI patients was less than controls (pleasant odor (po) 147.36±21.45 vs 323.11±39.76, unpleasant odor (upo) 201.86±24.93 vs 447.73±57.22, t(po)=4.241, t(upo)=5.365, both P<0.05). The activation range of whole brain in inhaling unpleasant odor was more than pleasant odor in controls (447.73±57.22 vs 323.11±39.76, t=3.936, P<0.05). The number of activator in ROI(awo) in MCI patients was less than controls (pleasant odor (po) 51.0[8.0, 109.0](M[P(25), P(75)]) vs 135.0[21.0, 321.5], unpleasant odor (upo) 65.0[6.0, 158.0]vs 205.0[36.5, 491.0], Z(po)=-2.199, Z(upo)=-2.216, both P<0.05). The number of activator in POC in MCI patients was less than controls (pleasant odor (po) 19.0[4.0, 35.5]vs 46.0[9.0, 118.5], unpleasant odor (upo) 26.0[2.0, 51.0]vs 79.0[17.5, 189.0], Z(po)=-1.898, Z(upo)=-2.167, both P<0.05). The number of activator in POC was negatively correlated with olfactory discriminate threshold in MCI patients (r(po)=-0.415, r(upo)=-0.409, both P<0.05). The number of activator in POC was positively correlated with MoCA in MCI patients (r(po)=0.289, r(upo)=0.296, both P<0.05). Conclusion: Olfactory fMRI can objectively assess the olfactory function in MCI, it is a imaging indicator with neuropsychological tests for detection in MCI, the number of activator in POC can reflect the severity of MCI.

Identification of eight new MHC-DPB1 alleles in the Tibetan macaques (Macaca thibetana)

We report here the identification of eight new Math-DPB1 alleles in the Tibetan macaques.

First identification of the MHC-DPB2 alleles in the rhesus macaques (Macaca mulatta)

We report here the identification of three MHC-DPB2 alleles in the rhesus macaques (Macaca mulatta).

[Relationship between large artery elasticity function and coronary heart disease, lower extremity arterial disease in patients with carotid plaque]

OBJECTIVE

To evaluate the relationship between large artery elastic function and coronary heart disease (CHD) or lower extremity arterial disease (LEAD) in patients with carotid plaque.

METHODS

A total of 491 patients with carotid plaque were enrolled into the study with complete data of arterial stiffness detection and blood test [male: 208 and female: 283, and mean age: (61.66±11.60) years]. All the subjects were divided into 2 groups according to CHD or LEAD, namely non-CHD&LEAD group (neither CHD nor LEAD) and CHD/LEAD group (either CHD or LEAD). Accor-ding to the mean age level (age<61.66 years or age>61.66 years), the independent association was analyzed between higher large arterial stiffness (carotid-femoral pulse wave velocity, CF-PWV, CF-PWV>9 m/s) and CHD/LEAD.

RESULTS

In the present research population, the mean level of arterial stiff-ness was high (the mean CF-PWV was 10.71 m/s), and 76.6% of them had arteriosclerosis, and 36.9% CHD/LEAD. The age, male and smoking proportion, systolic blood pressure (SBP), glycosylated hemoglobin (HbA1c), homocysteine (Hcy), creatinine (Cr), CF-PWV, prevalence rate of hypertension and diabetes mellitus, medication on hypertension, diabetes and hyperlipidemia were higher in CHD/LEAD group, and total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), and low density lipoprotein cholesterol (LDL-C) were lower in CHD/LEAD group than in non-CHD&LEAD group (all P<0.05).In multivariate Logistic regression analysis, the results showed that in the patients with age below 61.66 years, large artery stiffness (CF-PWV>9 m/s) was an independent risk factor of CHD/LEAD (OR=3.229, 95%CI 1.156-9.022, P<0.05); In the patients with age above 61.66 years, there was no independent association between large artery stiffness and CHD/LEAD (P>0.05).

CONCLUSION

The large artery elasticity function in the patients with carotid plaque was poor. In the patients with carotid plaque and higher large artery stiffness below 61.66 years, the risk of the prevalence of CHD/LEAD was increased significantly than with normal arterial stiffness. In the patients with carotid plaque below or above 61.66 years, the independent influencing factors on the prevalence of CHD/LEAD were different.

[Effect of occupational exposure on job burnout in nurses]

Objective: To investigate the effect of occupational exposure on job burnout in nurses, and to analyze the mediating effect of negative emotion between occupational exposure and job burnout and the regulatory effect of supervisor support on occupational exposure and negative emotion. Methods: From September to December, 2015, simple random sampling was used to select 543 nurses from six tertiary hospitals in Zhejiang Province, China. The questionnaires consisted of occupational exposure risk questionnaire, negative emotion questionnaire, supervisor support questionnaire, and job burnout questionnaire. Results: The total score of occupational exposure risk in nurses was 11.43±7.19; the score of emotional exhaustion was 3.19±1.24, the score of low sense of personal accomplishment was 3.02±1.21, and the score of sense of working indifference was 2.24±1.06. There were significant differences in occupational exposure score between nurses with different sexes (t=2.61, P<0.01) and working years (F=4.49, P<0.01) . There were significant differences in the scores of emotional exhaustion and low sense of personal accomplishment in nurses with different sexes (t=5.25, P<0.001) and working years (t=-3.48, P<0.01) . Occupational exposure had positive effects on negative emotion (β=0.41, P<0.05) , emotional exhaustion (β=0.47, P<0.05) , sense of working indifference (β=0.42, P<0.05) , and low sense of personal accomplishment (β=0.17, P<0.05) . Negative emotion had a partial mediating effect between occupational exposure and emotional exhaustion (total effect size 30.5%, P<0.05) and between occupational exposure and sense of working indifference (total effect size 37.1%, P<0.05) . Negative emotion had a complete mediating effect between occupational exposure and low sense of personal accomplishment (β=0.08, P>0.05) . Supervisor support negatively regulate the effects of occupational exposure and negative emotion (F=21.73, P<0.001) . Conclusion: In nurses, occupational exposure has a direct positive effect on job burnout and indirectly influences job burnout via negative emotion. Supervisor support can reduce the negative impact of occupational exposure on negative emotion.

Ten novel MHC-DPB1 alleles identified in Tibetan macaque (Macaca thibetana)

Ten novel MHC-DPB1 alleles of Tibetan macaque, were identified by cloning and sequencing.

Luminescence properties and warm white LED application of a ternary-alkaline fluoride red phosphor K2NaAlF6:Mn4+

Electroluminescence spectra and a photograph of a LED device featuring K₂NaAlF₆:Mn⁴⁺under 20 mA drive current as well as a CIE chromaticity diagram for the WLED.

[An analysis and literature review of two cases of autoimmune encephalitis with GABAB receptor antibodies]

Autoimmune encephalitis with GABA_B receptor antibodies has been rarely reported. Two cases of GABA_B receptor antibodies encephalitis were presented here.Epilepsy was the onset symptom, followed by declined consciousness and frequent seizures. Fever was presented in the whole course of the disease. Myorhythmia of the two hands and pilomotor seizures were shown in the later course of the disease. No specificity was demonstrated in electroencephalograms and magnetic resonance imaging. Sensitive response was shown to the first-line immunotherapy.

Use of hyperbaric oxygen on flaps and grafts in China: analysis of studies in the past 20 years

In China, hyperbaric oxygen (HBO2) has been widely applied in the treatment of ischemia/hypoxia related diseases including decompression sickness, carbon monoxide poisoning, diabetic foot ulcer and others. Wounds after skin grafts are an indication for HBO2 therapy in the Chinese Guideline for Hyperbaric Oxygen Therapy. In this study, we retrospectively reviewed the available studies on the application of HBO2 in the management of skin flaps. The mechanisms underlying the therapeutic effects of HBO2 were summarized, and therapeutic aspects in the HBO2 therapy of skin flaps in China were also described. Finally, some important issues influencing the therapeutic efficacy and further systemic reviews are proposed. Our findings may help to improve the quality of future studies in this field and to more rationally apply HBO2 therapy in patients receiving skin grafting procedures.

Origin of magnetic circular dichroism in GaMnAs: giant zeeman splitting versus spin dependent density of states

We present a unified interpretation of experimentally observed magnetic circular dichroism (MCD) in the ferromagnetic semiconductor (Ga,Mn)As, based on theoretical arguments, which demonstrates that MCD in this material arises primarily from a difference in the density of spin-up and spin-down states in the valence band brought about by the presence of the Mn impurity band, rather than being primarily due to the Zeeman splitting of electronic states.

UGT1A1 haplotype mutation among Asians in Singapore

BACKGROUND

The uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) enzyme is responsible for conjugation of the bilirubin in the liver as well as for drug metabolism. Some of the polymorphisms have been associated with an increased risk of neonatal hyperbilirubinemia which may explain the increased incidence of jaundice in an Asian population as well as exaggerated irinotecan-induced leukopenia.

OBJECTIVE

The local Asian incidence of hypomorphic haplotypes, defined as gene mutations known to have a reduced function, has not been described. Clinical correlation between the mutations and the need for phototherapy for hyperbilirubinemia was carried out.

METHODS

A cohort of 241 consecutive term infants delivered in the National University Hospital, Singapore, was recruited with parental consent. Cord blood was collected, and the promoter and coding regions of the UGT1A1 gene were sequenced.

RESULTS

Six known haplotypes and 2 novel haplotypes were identified: 1 wild type, 5 with reduced function, while the 2 novel ones were predicted to have decreased function. The frequency of these hypomorphic haplotypes was high. Among the 241 infants screened, 35% had 1 hypomorphic haplotype and 12% had 2 hypomorphic haplotypes. The frequency was also different among ethnic groups, with 48% Chinese, 64% Indian and 31% Malay infants having at least 1 hypomorphic haplotype (chi(2) test, p < 0.05). There was a trend seen between the number of G71R mutations and the need for phototherapy (chi2 test for trend, p < 0.05).

CONCLUSIONS

The local Asian incidence of hypomorphic haplotypes was high and there was a trend between the number of G71R mutations and the need for phototherapy. The G71R mutation may account for the increased incidence of neonatal jaundice seen in Asian populations.

Spectrofluorimetric determination of thiols by use of N[P-(2-benzoxazolyl)phenyl]maleimide

The weak fluorescence of N-[P-(2-benzoxazolyl)phenyl]maleimide (BOPM) can be greatly enhanced by thiol-containing compounds. A sensitive and simple spectrofluorimetric method based on the use of BOPM has been developed for the determination of thiols such as cysteine (Cys) and reduced glutathione (GSH). Calibration plots were linear in the concentration range from 0 to 1.6 x 10(-7) mol L(-1) for Cys and 0 to 1.7 x 10(-7) mol L(-1) for GSH. The detection limits (3a) were 2.36 x 10(-10) mol L(-1) for Cys and 1.49 x 10(-10) mol L(-1) for GSH. Many other amino acids (present at 100-fold greater concentrations) did not interfere with the determination. The proposed method has been used for the determination of Cys in protein hydrolysate and cystine electrolyte or GSH in serum, with recoveries of 95.4-103.7%.

[Comparison of the effectiveness of levofloxacin and cefuroxime for the treatment of sinusitis]

OBJECTIVE

To observe the effectiveness of levofloxacin and cefuroxime for the treatment of sinusitis in adults.

METHOD

Patients with acute or chronic sinusitis were randomly assigned to receive either levofloxacin (200 mg orally once daily, 200/100 mg twice daily) or cefuroxime (250 mg orally twice daily) for 10 to 14 days. Pre- or post-treatment, the clinical and laboratory examination were done and in the end of treatment, the efficacy and safety were assessment.

RESULT

The success rates after the end of treatment were 97.4% for the 76 patients who received levofloxacin and 92.8% for the 14 patients who received cefuroxime. The resolution rates of bacteria were 91.6% and 80.0%, respectively. The safety of these two groups were more high.

CONCLUSION

Levofloxacin is effective for the treatment of sinusitis in adults and pay attention to the course of treatment for raising the efficacy of treatment.

Spontaneous activation of beta(2)- but not beta(1)-adrenoceptors expressed in cardiac myocytes from beta(1)beta(2) double knockout mice

Although ligand-free, constitutive beta(2)-adrenergic receptor (AR) signaling has been demonstrated in naive cell lines and in transgenic mice overexpressing cardiac beta(2)-AR, it is unclear whether the dominant cardiac beta-AR subtype, beta(1)-AR, shares the ability of spontaneous activation. In the present study, we expressed human beta(1)- or beta(2)-AR via recombinant adenoviral infection in ventricular myocytes isolated from beta(1)beta(2)-AR double knockout mice, creating pure beta(1)-AR and beta(2)-AR systems with variable receptor densities. A contractile response to a nonselective beta-AR agonist, isoproterenol, was absent in double knockout mouse myocytes but was fully restored after adenoviral beta(1)-AR or adenoviral beta(2)-AR infection. Increasing the titer of adenoviral vectors (multiplicity of infection 10-1000) led to a dose-dependent expression of beta(1)- or beta(2)-AR with a maximal density of 1207 +/- 173 (36-fold over the wild-type control value) and 821+/-38 fmol/mg protein (69-fold), respectively. Using confocal immunohistochemistry, we directly visualized the cellular distribution of beta(1)-AR and beta(2)-AR and found that both subtypes were distributed on the cell surface membrane and transverse tubules, resulting in a striated pattern. In the absence of ligand, beta(2)-AR expression resulted in graded increases in baseline cAMP and contractility up to 428% and 233% of control, respectively, at the maximal beta(2)-AR density. These effects were specifically reversed by a beta(2)-AR inverse agonist, ICI 118,551 (10(-7) M). In contrast, overexpression of beta(1)-AR, even at a greater density, failed to enhance either basal cAMP or contractility; the alleged beta(1)-AR inverse agonist, CGP 20712A (10(-6) M), had no significant effect on basal contraction in these cells. Thus, we conclude that acute beta(2)-AR overexpression in cardiac myocytes elicits significant physiological responses due to spontaneous receptor activation; however, this property is beta-AR subtype specific because beta(1)-AR does not exhibit agonist-independent spontaneous activation.

Sinoatrial node pacemaker activity requires Ca(2+)/calmodulin-dependent protein kinase II activation

Cardiac beating arises from the spontaneous rhythmic excitation of sinoatrial (SA) node cells. Here we report that SA node pacemaker activity is critically dependent on Ca(2+)/calmodulin-dependent protein kinase II (CaMKII). In freshly dissociated rabbit single SA node cells, inhibition of CaMKII by a specific peptide inhibitor, autocamtide-2 inhibitory peptide (AIP, 10 micromol/L), or by KN-93 (0.1 to 3.0 micromol/L), but not its inactive analog, KN-92, depressed the rate and amplitude of spontaneous action potentials (APs) in a dose-dependent manner. Strikingly, 10 micromol/L AIP and 3 micromol/L KN-93 completely arrested SA node cells, which indicates that basal CaMKII activation is obligatory to the genesis of pacemaker AP. To understand the ionic mechanisms of the CaMKII effects, we measured L-type Ca(2+) current (I(Ca, L)), which contributes both to AP upstroke and to pacemaker depolarization. KN-93 (1 micromol/L), but not its inactive analog, KN-92, decreased I:(Ca, L) amplitude from 12+/-2 to 6+/-1 pA/pF without altering the shape of the current-voltage relationship. Both AIP and KN-93 shifted the midpoint of the steady-state inactivation curve leftward and markedly slowed the recovery of I(Ca, L) from inactivation. Similar results were observed using the fast Ca(2+) chelator BAPTA, whereas the slow Ca(2+) chelator EGTA had no significant effect, which suggests that CaMKII activity is preferentially regulated by local Ca(2+) transients. Indeed, confocal immunocytochemical imaging showed that active CaMKII is highly localized beneath the surface membrane in the vicinity of L-type channels and that AIP and KN-93 significantly reduced CaMKII activity. Thus, we conclude that CaMKII plays a vital role in regulating cardiac pacemaker activity mainly via modulating I(Ca, L) inactivation and reactivation, and local Ca(2+) is critically involved in these processes.

Inhibition of spontaneous beta 2-adrenergic activation rescues beta 1-adrenergic contractile response in cardiomyocytes overexpressing beta 2-adrenoceptor

Cardiac-specific overexpression of the human beta(2)-adrenergic receptor (AR) in transgenic mice (TG4) enhances basal cardiac function due to ligand-independent spontaneous beta(2)-AR activation. However, agonist-mediated stimulation of either beta(1)-AR or beta(2)-AR fails to further enhance contractility in TG4 ventricular myocytes. Although the lack of beta(2)-AR response has been ascribed to an efficient coupling of the receptor to pertussis toxin-sensitive G(i) proteins in addition to G(s), the contractile response to beta(1)-AR stimulation by norepinephrine and an alpha(1)-adrenergic antagonist prazosin is not restored by pertussis toxin treatment despite a G(i) protein elevation of 1.7-fold in TG4 hearts. Since beta-adrenergic receptor kinase, betaARK1, activity remains unaltered, the unresponsiveness of beta(1)-AR is not caused by betaARK1-mediated receptor desensitization. In contrast, pre-incubation of cells with anti-adrenergic reagents such as muscarinic receptor agonist, carbachol (10(-5)m), or a beta(2)-AR inverse agonist, ICI 118,551 (5 x 10(-7)m), to abolish spontaneous beta(2)-AR signaling, both reduce the base-line cAMP and contractility and, surprisingly, restore the beta(1)-AR contractile response. The "rescued" contractile response is completely reversed by a beta(1)-AR antagonist, CGP 20712A. Furthermore, these results from the transgenic animals are corroborated by in vitro acute gene manipulation in cultured wild type adult mouse ventricular myocytes. Adenovirus-directed overexpression of the human beta(2)-AR results in elevated base-line cAMP and contraction associated with a marked attenuation of beta(1)-AR response; carbachol pretreatment fully revives the diminished beta(1)-AR contractile response. Thus, we conclude that constitutive beta(2)-AR activation induces a heterologous desensitization of beta(1)-ARs independent of betaARK1 and G(i) proteins; suppression of the constitutive beta(2)-AR signaling by either a beta(2)-AR inverse agonist or stimulation of the muscarinic receptor rescues the beta(1)-ARs from desensitization, permitting agonist-induced contractile response.

Culture and adenoviral infection of adult mouse cardiac myocytes: methods for cellular genetic physiology

Rapid development of transgenic and gene-targeted mice and acute genetic manipulation via gene transfer vector systems have provided powerful tools for cardiovascular research. To facilitate the phenotyping of genetically engineered murine models at the cellular and subcellular levels and to implement acute gene transfer techniques in single mouse cardiomyocytes, we have modified and improved current enzymatic methods to isolate a high yield of high-quality adult mouse myocytes (5.3 +/- 0.5 x 10(5) cells/left ventricle, 83.8 +/- 2.5% rod shaped). We have also developed a technique to culture these isolated myocytes while maintaining their morphological integrity for 2-3 days. The high percentage of viable myocytes after 1 day in culture (72.5 +/- 2.3%) permitted both physiological and biochemical characterization. The major functional aspects of these cells, including excitation-contraction coupling and receptor-mediated signaling, remained intact, but the contraction kinetics were significantly slowed. Furthermore, gene delivery via recombinant adenoviral infection was highly efficient and reproducible. In adult beta(1)/beta(2)-adrenergic receptor (AR) double-knockout mouse myocytes, adenovirus-directed expression of either beta(1)- or beta(2)-AR, which occurred in 100% of cells, rescued the functional response to beta-AR agonist stimulation. These techniques will permit novel experimental settings for cellular genetic physiology.

Constitutive beta2-adrenergic signalling enhances sarcoplasmic reticulum Ca2+ cycling to augment contraction in mouse heart

1. Transgenic overexpression of the beta2-adrenergic receptor (beta2AR) in mouse heart augments baseline cardiac function in a ligand-independent manner, due to the presence of spontaneously active beta2AR (beta2AR*). This study aims to elucidate the mechanism of beta2AR*-mediated modulation of cardiac excitation-contraction (EC) coupling. 2. Confocal imaging was used to analyse Ca2+ sparks and spatially resolve Ca2+ transients in single ventricular myocytes from transgenic (TG4) and non-transgenic (NTG) littermates. Whole-cell voltage- and current-clamp techniques were used to record L-type Ca2+ currents (ICa) and action potentials, respectively. 3. In the absence of any beta2AR ligand, TG4 myocytes had greater contraction amplitudes, larger Ca2+ transients and faster relaxation times than did NTG cells. 4. The action potentials of TG4 and NTG myocytes were similar, except for a prolonged end-stage repolarization in TG4 cells; the ICa density and kinetics were nearly identical. The relationship between peak Ca2+ and contraction, which reflects myofilament Ca2+ sensitivity, was similar. 5. In TG4 cells, the frequency of Ca2+ sparks (spontaneous or evoked at -40 mV) was 2-7 times greater, despite the absence of change in the resting Ca2+, sarcoplasmic reticulum (SR) Ca2+ content, and ICa. Individual sparks were brighter, broader and lasted longer, leading to a 2.3-fold greater signal mass. Thus, changes in both spark frequency and size underlie the greater Ca2+ transient in TG4 cells. 6. The inverse agonist ICI 118,551 (ICI, 5 x 10-7 M), which blocks spontaneous beta2AR activation, reversed the aforementioned beta2AR* effects on cardiac EC coupling without affecting the sarcolemmal ICa. However, ICI failed to detect significant constitutive beta2AR activity in NTG cells. 7. We conclude that beta2AR*-mediated signalling enhances SR release channel activity and Ca2+-induced Ca2+ release in TG4 cardiac myocytes, and that beta2AR* enhances EC coupling by reinforcing SR Ca2+ cycling (release and reuptake), but bypassing the sarcolemmal ICa.

Recent advances in cardiac beta(2)-adrenergic signal transduction

Recent studies have added complexities to the conceptual framework of cardiac beta-adrenergic receptor (beta-AR) signal transduction. Whereas the classical linear G(s)-adenylyl cyclase-cAMP-protein kinase A (PKA) signaling cascade has been corroborated for beta(1)-AR stimulation, the beta(2)-AR signaling pathway bifurcates at the very first postreceptor step, the G protein level. In addition to G(s), beta(2)-AR couples to pertussis toxin-sensitive G(i) proteins, G(i2) and G(i3). The coupling of beta(2)-AR to G(i) proteins mediates, to a large extent, the differential actions of the beta-AR subtypes on cardiac Ca(2+) handling, contractility, cAMP accumulation, and PKA-mediated protein phosphorylation. The extent of G(i) coupling in ventricular myocytes appears to be the basis of the substantial species-to-species diversity in beta(2)-AR-mediated cardiac responses. There is an apparent dissociation of beta(2)-AR-induced augmentations of the intracellular Ca(2+) (Ca(i)) transient and contractility from cAMP production and PKA-dependent cytoplasmic protein phosphorylation. This can be largely explained by G(i)-dependent functional compartmentalization of the beta(2)-AR-directed cAMP/PKA signaling to the sarcolemmal microdomain. This compartmentalization allows the common second messenger, cAMP, to perform selective functions during beta-AR subtype stimulation. Emerging evidence also points to distinctly different roles of these beta-AR subtypes in modulating noncontractile cellular processes. These recent findings not only reveal the diversity and specificity of beta-AR and G protein interactions but also provide new insights for understanding the differential regulation and functionality of beta-AR subtypes in healthy and diseased hearts.

Heterogeneous changes in K currents in rat ventricles three days after myocardial infarction

OBJECTIVE

After coronary artery occlusion, surviving myocardium in and around the infarct zone plays an important role in arrhythmogenesis. Understanding the mechanisms for derangements in cardiac electrical activity at the cellular and molecular levels is important for the design of effective therapeutic strategies.

METHODS

To provide part of that understanding, we studied changes in K channel function and expression in rat ventricular myocardium three days after occluding the left major coronary artery. The epicardium and endocardium of infarcted region in the left ventricle and the free wall of right ventricle were separated for myocyte isolation, followed by whole-cell voltage clamp studies. Myocytes were also isolated from corresponding regions of control and sham-operated hearts and studied under the same conditions.

RESULTS

We found that the transient outward (Ito), delayed rectifier (IK) and inward rectifier (IKI) currents have different distribution patterns in normal rat ventricular myocardium. Sham-operation did not affect any of these K currents in left ventricular myocytes, but coronary artery occlusion caused a reduction of all three. For Ito and IKI the reduction was greater in epicardial than in endocardial myocytes, but IK was reduced equally in these two cell groups. Unexpectedly, Ito and IK as well as cell capacitance were increased in right ventricular myocytes from infarcted as well as sham-operated hearts. Western blot analysis indicated that the level of Kv4 channel proteins (Kv4.2 + Kv4.3) was reduced in infarcted left ventricular myocardium, consistent with the reduction in Ito.

CONCLUSION

Our data suggest that the distribution of K channels and changes in them induced by coronary artery occlusion are heterogeneous in ventricular myocardium. Understanding the molecular mechanisms for this heterogeneity and its implications in arrhythmogenesis poses a challenge in designing effective antiarrhythmic therapy for myocardial infarction patients.

Spontaneous beta(2)-adrenergic signaling fails to modulate L-type Ca(2+) current in mouse ventricular myocytes

A receptor can be activated either by specific ligand-directed changes in conformation or by intrinsic, spontaneous conformational change. In the beta(2)-adrenergic receptor (AR) overexpression transgenic (TG4) murine heart, spontaneously activated beta(2)AR (beta(2)-R*) in the absence of ligands has been evidenced by elevated basal adenylyl cyclase activity and cardiac function. In the present study, we determined whether the signaling mediated by beta(2)-R* differs from that of a ligand-elicited beta(2)AR activation (beta(2)-LR*). In ventricular myocytes from TG4 mice, the properties of L-type Ca(2+) current (I(Ca)), a major effector of beta(2)-LR* signaling, was unaltered, despite a 2.5-fold increase in the basal cAMP level and a 1.9-fold increase in baseline contraction amplitude as compared with that of wild-type (WT) cells. Although the contractile response to beta(2)-R* in TG4 cells was abolished by a beta(2)AR inverse agonist, ICI118,551 (5 x 10(-7) M), or an inhibitory cAMP analog, Rp-CPT-cAMPS (10(-4) M), no change was detected in the simultaneously recorded I(Ca). These results suggest that the increase in basal cAMP due to beta(2)-R*, while increasing contraction amplitude, does not affect I(Ca) characteristics. In contrast, the beta(2)AR agonist, zinterol elicited a substantial augmentation of I(Ca) in both TG4 and WT cells (pertussis toxin-treated), indicating that L-type Ca(2+) channel in these cells can respond to ligand-directed signaling. Furthermore, forskolin, an adenylyl cyclase activator, elicited similar dose-dependent increase in I(Ca) amplitude in WT and TG4 cells, suggesting that the sensitivity of L-type Ca(2+) channel to cAMP-dependent modulation remains intact in TG4 cells. Thus, we conclude that beta(2)-R* bypasses I(Ca) to modulate contraction, and that beta(2)-LR* and beta(2)-R* exhibit different intracellular signaling and target protein specificity.

G(i) protein-mediated functional compartmentalization of cardiac beta(2)-adrenergic signaling

In contrast to beta(1)-adrenoreceptor (beta(1)-AR) signaling, beta(2)-AR stimulation in cardiomyocytes augments L-type Ca(2+) current in a cAMP-dependent protein kinase (PKA)-dependent manner but fails to phosphorylate phospholamban, indicating that the beta(2)-AR-induced cAMP/PKA signaling is highly localized. Here we show that inhibition of G(i) proteins with pertussis toxin (PTX) permits a full phospholamban phosphorylation and a de novo relaxant effect following beta(2)-AR stimulation, converting the localized beta(2)-AR signaling to a global signaling mode similar to that of beta(1)-AR. Thus, beta(2)-AR-mediated G(i) activation constricts the cAMP signaling to the sarcolemma. PTX treatment did not significantly affect the beta(2)-AR-stimulated PKA activation. Similar to G(i) inhibition, a protein phosphatase inhibitor, calyculin A (3 x 10(-8) M), selectively enhanced the beta(2)-AR but not beta(1)-AR-mediated contractile response. Furthermore, PTX and calyculin A treatment had a non-additive potentiating effect on the beta(2)-AR-mediated positive inotropic response. These results suggest that the interaction of the beta(2)-AR-coupled G(i) and G(s) signaling affects the local balance of protein kinase and phosphatase activities. Thus, the additional coupling of beta(2)-AR to G(i) proteins is a key factor causing the compartmentalization of beta(2)-AR-induced cAMP signaling.

beta2-adrenergic cAMP signaling is uncoupled from phosphorylation of cytoplasmic proteins in canine heart

BACKGROUND

Recent studies of beta-adrenergic receptor (beta-AR) subtype signaling in in vitro preparations have raised doubts as to whether the cAMP/protein kinase A (PKA) signaling is activated in the same manner in response to beta2-AR versus beta1-AR stimulation.

METHODS AND RESULTS

The present study compared, in the intact dog, the magnitude and characteristics of chronotropic, inotropic, and lusitropic effects of cAMP accumulation, PKA activation, and PKA-dependent phosphorylation of key effector proteins in response to beta-AR subtype stimulation. In addition, many of these parameters and L-type Ca2+ current (ICa) were also measured in single canine ventricular myocytes. The results indicate that although the cAMP/PKA-dependent phosphorylation cascade activated by beta1-AR stimulation could explain the resultant modulation of cardiac function, substantial beta2-AR-mediated chronotropic, inotropic, and lusitropic responses occurred in the absence of PKA activation and phosphorylation of nonsarcolemmal proteins, including phospholamban, troponin I, C protein, and glycogen phosphorylase kinase. However, in single canine myocytes, we found that beta2-AR-stimulated increases in both ICa and contraction were abolished by PKA inhibition. Thus, the beta2-AR-directed cAMP/PKA signaling modulates sarcolemmal L-type Ca2+ channels but does not regulate PKA-dependent phosphorylation of cytoplasmic proteins.

CONCLUSIONS

These results indicate that the dissociation of beta2-AR signaling from cAMP regulatory systems is only apparent and that beta2-AR-stimulated cAMP/PKA signaling is uncoupled from phosphorylation of nonsarcolemmal regulatory proteins involved in excitation-contraction coupling.

Coupling of beta2-adrenoceptor to Gi proteins and its physiological relevance in murine cardiac myocytes

-Transgenic mouse models have been developed to manipulate beta-adrenergic receptor (betaAR) signal transduction. Although several of these models have altered betaAR subtypes, the specific functional sequelae of betaAR stimulation in murine heart, particularly those of beta2-adrenergic receptor (beta2AR) stimulation, have not been characterized. In the present study, we investigated effects of beta2AR stimulation on contraction, [Ca2+]i transient, and L-type Ca2+ currents (ICa) in single ventricular myocytes isolated from transgenic mice overexpressing human beta2AR (TG4 mice) and wild-type (WT) littermates. Baseline contractility of TG4 heart cells was increased by 3-fold relative to WT controls as a result of the presence of spontaneous beta2AR activation. In contrast, beta2AR stimulation by zinterol or isoproterenol plus a selective beta1-adrenergic receptor (beta1AR) antagonist CGP 20712A failed to enhance the contractility in TG4 myocytes, and more surprisingly, beta2AR stimulation was also ineffective in increasing contractility in WT myocytes. Pertussis toxin (PTX) treatment fully rescued the ICa, [Ca2+]i, and contractile responses to beta2AR agonists in both WT and TG4 cells. The PTX-rescued murine cardiac beta2AR response is mediated by cAMP-dependent mechanisms, because it was totally blocked by the inhibitory cAMP analog Rp-cAMPS. These results suggest that PTX-sensitive G proteins are responsible for the unresponsiveness of mouse heart to agonist-induced beta2AR stimulation. This was further corroborated by an increased incorporation of the photoreactive GTP analog [gamma-32P]GTP azidoanilide into alpha subunits of Gi2 and Gi3 after beta2AR stimulation by zinterol or isoproterenol plus the beta1AR blocker CGP 20712A. This effect to activate Gi proteins was abolished by a selective beta2AR blocker ICI 118,551 or by PTX treatment. Thus, we conclude that (1) beta2ARs in murine cardiac myocytes couple to concurrent Gs and Gi signaling, resulting in null inotropic response, unless the Gi signaling is inhibited; (2) as a special case, the lack of cardiac contractile response to beta2AR agonists in TG4 mice is not due to a saturation of cell contractility or of the cAMP signaling cascade but rather to an activation of beta2AR-coupled Gi proteins; and (3) spontaneous beta2AR activation may differ from agonist-stimulated beta2AR signaling.

Stabilization of a channel's open state by a hydrophobic residue in the sixth membrane-spanning segment (S6) of rKv1.4

We report the effects of mutating a threonine residue at position 529 (T529) in the middle of the S6 segment of rKv1.4 on the voltage-dependence and kinetics of activation and deactivation. Replacing T529 with glycine (no side chain) or with a residue that has a hydrophobic side chain (T529L, T529I, T529V, T529A, or T529F) caused a slowing of deactivation, along with a negative shift in the activation curve and a voltage-dependent slowing of activation. Numerical simulation showed that these effects could be reproduced by decreasing the rate constant for a transition from open to closed states. The degree of slowing of deactivation largely correlated with the degree of increase in 529 side-chain hydrophobicity. Specifically, the 529 mutation-induced alteration in free energy change accompanying deactivation per channel could be accounted for by the increase in free energy needed to transfer the 529 side chain of one subunit from a hydrophobic environment to an aqueous environment. We propose that in the open state, the 529 side chain faces a hydrophobic protein interior. The rate-limiting step in channel deactivation includes a conformational change in one subunit's S6 segment, moving its 529 side chain to face the aqueous lumen of the pore.

Age-associated alterations in calcium current and its modulation in cardiac myocytes

The calcium current is one of the most important components in cardiac excitation-contraction coupling. During aging, the magnitude of L-type Ca++ channel current (ICa,L) is significantly increased in parallel with the enlargement of cardiac myocytes, resulting in unaltered ICa,L density. Since the inactivation of ICa,L is slowed and the action potential duration is prolonged, the net Ca++ influx during each action potential is likely to be increased in senescent hearts relative to young ones. This augmentation of Ca++ influx may be important for the preserved cardiac function of the older heart in the basal state. However, it increases the risk of Ca++ overload and Ca(++)-dependent arrhythmias in the senescent heart. During stress, the response of ICa,L to beta-adrenergic receptor stimulation is markedly reduced, which may be an important cause of the age-related decrease in cardiac reserve function. These age-dependent changes in ICa,L and its modulations are similar to those observed in the enlarged myocytes of the hypertrophied and failing heart.

The ionic mechanisms of early after depolarization in mouse ventricular myocytes: the role of IK1

The occurrence of early after depolarization (EAD) in single mouse ventricular myocytes was observed and its ionic mechanisms were studied using the patch clamp technique. Under treatment with perfusion of Tyrode's solution containing 3 mM KCl and 3 mM CsCl, 3/6 cases exhibited EAD, while with 3 mM KCl or 3 mM CsCl alone, EAD was not induced. The background steady-state current-voltage (I-V) curves of the myocytes showed no negative slope, i.e., the slope in the range of 50 mV positive to the reversal potential was virtually flat and stayed at a low current level. Under perfusion of 3 mM KCl and 3 mM CsCl, the outward current in the above region decreased nearly to 0: in the myocytes which exhibited EAD, a net inward current (crossover) was displayed in the same region, which was abolished by 10 microM TTX and 10 microM nifedipine. The results of whole-cell inward rectifier current I-V curves were similar to the above background steady-state I-V curves. In mouse ventricular myocytes, transient outward current was very strong with a peak current density of 63 +/- 19 pA/pF, whereas low K+ and Cs+ had no significant effect. 11/30 cases showed obvious delayed rectifier current, but the tail current recorded by envelope method was relatively weak (1.19 +/- 0.35 pA/pF) and insensitive to CsCl or changing of the KCl concentration. The results suggest that under treatment with low K+ and Cs+, the inhibition of inward rectifier current is the basis of the formation of second plateau, while Na and Ca currents contribute to the generation of triggered bursts.