SIRT3-dependent mitochondrial redox homeostasis mitigates CHK1 inhibition combined with gemcitabine treatment induced cardiotoxicity in hiPSC-CMs and mice

Administration of CHK1-targeted anticancer therapies is associated with an increased cumulative risk of cardiac complications, which is further amplified when combined with gemcitabine. However, the underlying mechanisms remain elusive. In this study, we generated hiPSC-CMs and murine models to elucidate the mechanisms underlying CHK1 inhibition combined with gemcitabine-induced cardiotoxicity and identify potential targets for cardioprotection. Mice were intraperitoneally injected with 25 mg/kg CHK1 inhibitor AZD7762 and 20 mg/kg gemcitabine for 3 weeks. hiPSC-CMs and NMCMs were incubated with 0.5 uM AZD7762 and 0.1 uM gemcitabine for 24 h. Both pharmacological inhibition or genetic deletion of CHK1 and administration of gemcitabine induced mtROS overproduction and pyroptosis in cardiomyocytes by disrupting mitochondrial respiration, ultimately causing heart atrophy and cardiac dysfunction in mice. These toxic effects were further exacerbated with combination administration. Using mitochondria-targeting sequence-directed vectors to overexpress CHK1 in cardiomyocyte (CM) mitochondria, we identified the localization of CHK1 in CM mitochondria and its crucial role in maintaining mitochondrial redox homeostasis for the first time. Mitochondrial CHK1 function loss mediated the cardiotoxicity induced by AZD7762 and CHK1-knockout. Mechanistically, mitochondrial CHK1 directly phosphorylates SIRT3 and promotes its expression within mitochondria. On the contrary, both AZD7762 or CHK1-knockout and gemcitabine decreased mitochondrial SIRT3 abundance, thus resulting in respiration dysfunction. Further hiPSC-CMs and mice experiments demonstrated that SIRT3 overexpression maintained mitochondrial function while alleviating CM pyroptosis, and thereby improving mice cardiac function. In summary, our results suggest that targeting SIRT3 could represent a novel therapeutic approach for clinical prevention and treatment of cardiotoxicity induced by CHK1 inhibition and gemcitabine.

Eukaryotic translation elongation factor 1 alpha (eEF1A) inhibits Siniperca chuatsi rhabdovirus (SCRV) infection through two distinct mechanisms

IMPORTANCE

Although a virus can regulate many cellular responses to facilitate its replication by interacting with host proteins, the host can also restrict virus infection through these interactions. In the present study, we showed that the host eukaryotic translation elongation factor 1 alpha (eEF1A), an essential protein in the translation machinery, interacted with two proteins of a fish rhabdovirus, Siniperca chuatsi rhabdovirus (SCRV), and inhibited virus infection via two different mechanisms: (i) inhibiting the formation of crucial viral protein complexes required for virus transcription and replication and (ii) promoting the ubiquitin-proteasome degradation of viral protein. We also revealed the functional regions of eEF1A that are involved in the two processes. Such a host protein inhibiting a rhabdovirus infection in two ways is rarely reported. These findings provided new information for the interactions between host and fish rhabdovirus.

[A cross-sectional survey and analysis of influencing factors of humanistic of the current status of humanistic care ability of burn specialist nurses]

Objective: To investigate the current status of humanistic care ability of burn specialist nurses and to analyze the influencing factors. Methods: A single-center cross-sectional research method was conducted. From May to August 2020, 63 burn specialist nurses who met the inclusion criteria in Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine were selected. Self-made general data questionnaire was used to investigate 17 indexes, including gender, age, professional title, working years, whether received humanistic care training, academic qualification, and caring ability inventory (CAI) was used to evaluate their humanistic care ability. After the nurses were classified by the general data, independent sample t test and one-way analysis of variance were performed on the data to analyze the total score of CAI. The CAI total scores and scores of cognition, courage, and patience of the nurses were compared with the international norm. The factors with statistically significant differences in unvariate analysis were selected for multiple linear regression analysis to screen the independent influencing factors of humanistic care ability of burn specialist nurses. Results: A total of 63 questionnaires were collected in this survey, all of which were valid. Among the 63 nurses, there were 4 males and 59 females, with the age mainly ranging from 20 to 30 years (30 nurses, 47.62%), the professional titles mainly being nurse practitioner (36 nurses, 57.14%), the working years mainly being more than 10 years (28 nurses, 44.44%), 32 nurses not receiving humanistic care training, and academic qualifications mostly being junior college (37 nurses, 58.73%). There were significant differences in the total scores of CAI among nurses with different ages, professional titles, working years, whether received humanistic care training, and academic qualifications (with F values of 53.95, 49.14, and 75.42, t values of 6.08 and -2.82, respectively, P<0.01). The scores of cognition, courage, and patience and the total scores of CAI of nurses in this group were significantly lower than those of international norm (with t values of -2.02, -2.04, -6.19, and -3.89, respectively, P<0.05 or P<0.01). Multiple linear regression analysis showed that age, working years, professional title, and whether received humanistic care training were the independent influencing factors of humanistic care ability of burn specialist nurses (with 95% confidence intervals of 1.91-23.23, 16.25-31.48, 1.05-19.09, and 6.72-31.82, unstandardized coefficient values of 12.57, 23.86, 10.07, and 19.27, respectively, P<0.05 or P<0.01). Conclusions: The humanistic care ability of burn specialist nurses is relatively weak. Age, professional title, working years, and whether received humanistic care training are the independent influencing factors of humanistic care ability of burn specialist nurses.

[Some HBeAg-negative chronic hepatitis B patients treated with nucleos(t)ide analogue can achieve HBsAg loss after drug withdrawal: stop-to-cure may be coming]

Nucleoside/Nucleotide analogues (NAs) are widely used for the antiviral treatment of chronic hepatitis B (CHB), however, it is difficult to achieve serum hepatitis B surface antigen (HBsAg) loss with NAs therapy. In recent years, several prospective trails have reported that HBsAg loss (functional cure or clinical cure) also occurs in a small number of hepatitis B e antigen (HBeAg) negative CHB patients who discontinued long-term treatment with NAs. Accordingly, the "stop-to-cure" strategy is proposed. Although the mechanism has not been fully elucidated, the known factors related to serum HBsAg loss with NAs withdrawal include HBV genotype, duration of NAs treatment, serum HBsAg and HBV RNA levels at end-of-treatment, and ethnic differences. In the review, we discuss the best time to stop NAs therapy, the potential markers for predicting relapse after cessation of NAs and the possible mechanism of "stop-to-cure" in HBeAg-negative CHB patients, and propose some suggestions on the time of retreatment.

[Characteristics and regulatory mechanisms of lipid metabolism remodeling after malignant transformation of glioma-associated macrophages]

Objective: To observe the lipid metabolism characteristics of tumor-associated macrophages (TAM) after malignant transformation in the glioma micro-environment, and analyze the biological phenotype changes and regulatory mechanisms after inhibiting the lipid metabolism remodeling. Methods: Twelve male Balb/c mice of 6-8 weeks were used in the study. Macrophages (Mφ) were derived from mouse bone marrow, and malignantly transformed macrophages (tMφ₁ and tMφ₂) were cloned from the model of glioma stem cell (GSC) through interaction with Mφ in vivo and in vitro. Intracellular lipid droplet formation and cellular cholesterol content were measured respectively in Mφ, tMφ₁ and tMφ₂. qRT-PCR was performed to detect the genes expression level related with lipid metabolism, including sterol regulatory element binding protein (SREBP), fatty acid synthase (FASN), and 3-hydroxy-3-methylglutarate monoacyl coenzyme A reductase (HMG-CoA). Simvastatin (SIM) was used to analyze the proliferation, immigration and invasiveness ability in tMφ₁ and tMφ₂ after inhibition of the lipid metabolism. Differential expression profiles of miRNAs after SIM treatment were constructed in t-Mφ₁ and bio-informatics analysis was screened and verified for miR449a and its target gene sorting micro-tubule connectin 17 (SNX17) associated with lipid metabolism remodeling. The effect on SNX17 by up-regulated miR-449a were analyzed by qRT-PCR and Western blot, meanwhile, the biological phenotype and cholesterol content were observed after up-regulation of miR449a. Low-density lipoprotein receptor (LDLR) protein levels after SNX17 knockdown and intracellular cholesterol content after LDLR knockdown were detected respectively. Results: The numbers of intracellular lipid droplet formation in tMφ₁ and tMφ₂ were more than that in Mφ (P<0.001). Likewise, the relative contents of cholesterol (3.89±0.68 and 3.56±0.53), SREBP (4.78±0.60 and 2.84±0.41), FASN (4.65±0.70 and 3.01±0.45), and HMG-CoA (5.74±0.55 and 2.97±0.34) were significantly higher in tMφ₁ and tMφ₂ than those of Mφ (1.01 wel, 1.02 wel and 0.99 wel, respectively) (all P<0.001). The proliferation rates of tMφ₁ and tMφ₂ decreased from (47.06±5.88) % and (45.29±5.64)% to (23.53±4.70)% and (18.74±5.76)%, respectively after treatment with SIM (both P<0.05). The numbers of migrated cells decreased from 1 025±138 and 350±47 to 205±63 and 99±25, respectively (both P<0.001). And the numbers of invasiveness cells decreased from 919±45 and 527±34 to 220±23 and 114±21, respectively (both P<0.001). While the relative intracellular cholesterol content decreased to 0.52±0.08 and 0.58±0.07 (both P<0.05), respectively. MiR-449a was screened from tMφ₁ by SIM, and the target gene was analyzed and verified to be SNX17. SNX17 expression was down-regulated, and the proliferation rate, the number of migration and invasiveness was significantly decreased after miR-449a over-expression (all P<0.05). Low-density lipoprotein receptor (LDLR) expression was down-regulated after knock-down of SNX17, while the cholesterol content was decreased after knock-down of LDLR in tMφ₁ and tMφ₂ (all P<0.05). Conclusions: Malignantly transformed TAMs undergo lipid metabolism remodeling characterized with enhanced lipid metabolism. MiR-449a regulates the LDLR by targeting SNX17, thereby affecting the lipid metabolism of malignantly transformed macrophages, and subsequently inhibiting its proliferation, migration, and invasion ability. Precise intervention with miR-449a/SNX17/LDLR axis could provide an experimental basis for reversing its tumor-promoting micro-environment remodeled by GSC through metabolic intervention.

[Associations between adverse childhood experiences and adulthood substance use among lesbians]

Objective: To investigate the associations between adverse childhood experiences (ACE) and substance use behaviors among lesbians to provide a scientific basis for high-risk population identification and formulation of targeted intervention measures. Methods: Lesbians who participated in routine AIDS voluntary counseling, testing services, activities, and peer recommendations were recruited from July to December 2018, with the help of LesPark in Beijing. Convenient sampling method was used. Demographic characteristics, ACE, and substance use behaviors of subjects were investigated using an online platform powered by www.wjx.cn. Subsequently, the associations between ACE and adulthood substance use behaviors were evaluated using the logistic regression model. The SPSS 22.0 was used for statistical analysis. Results: A total of 294 lesbians were recruited in the study, 81.3% (239/294) of them were lesbians, and 18.7% (55/294) were bisexuals. Besides, 55.8% (164/294) of subjects reported they had had ACE, with proportions of lesbians experiencing abuse, neglect, and family dysfunction as 33.3% (98/294), 24.5% (72/294), and 32.7% (96/294), respectively. 55.1% (162/294) of the lesbians reported they had smoked in the past 30 days, 11.2% (33/294) reported having drug-use behavior in the past three months, and 22.8% (67/294) claimed drinking alcohol weekly. Multivariate logistic regression analysis showed that lesbians with ACE were at high risks to smoke (OR=1.87, 95%CI: 1.13-3.08), drink (OR=2.13, 95%CI: 1.18-3.84), and use drugs (OR=3.33, 95%CI: 1.29-8.61) in adulthood. Moreover, lesbians with childhood family dysfunction were at higher risk of smoking cigarettes (OR=2.60, 95%CI: 1.46-4.62) and drinking alcohol (OR=2.65, 95%CI: 1.44-4.87). At the same time, those with abuse experience were at higher risk of drug use (OR=3.17, 95%CI: 1.26-7.96). Conclusions: Substance use behaviors, including cigarette smoking, drinking alcohol, and drugs use, were common among lesbians. Positive associations were found between ACE and adulthood substance use behaviors.

[Early physical growth and disease analysis among children born delivered by HBsAg-positive mothers]

Objective: To estimate the early physical growth and disease in children born to HBsAg-positive mothers. Methods: This was a retrospective cohort study. Three areas as Xihu in Hangzhou, Lanxi in Jinhua, and Haiyan in Jiaxing in Zhejiang province were selected by cluster sampling. The growth outcomes of children born to HBsAg-positive mothers (exposure group) and matched 1∶1 women uninfected with HBV (control group) in 2014 were investigated and compared at birth, 6, 9, 12, and 18 months, respectively. There were totally 342 children in each group. Results: The incidences of low birth weight (LBW) for children born to exposure and control group were 1.8% (6/342), and 2.6% (9/342), respectively (P=0.433); and, rates of preterm birth were 2.3% (8/342), and 2.0% (7/342), respectively (P=0.794). The mean birth weight of children born to mothers without HBV infection (3.4±0.4) kg was dramatically higher than children in exposure group (3.3±0.4) kg (P=0.019). At 18 months, the average head circumference was significantly greater among children in control group (47.3±1.3) cm than children in exposure group (47.0±2.0) cm (P=0.038). Additional, mean birth weeks, height, weight, increases in height/weight/head circumference each month, weight/height/head circumference for age Z scores, proportion of growth retardation and low weight, disease prevalence were not observed statistically differences between two groups (P>0.05). All children born to HBsAg-positive mothers were received three-dose HBV vaccination. The rate of hepatitis B immunoglobulin for births born to HBsAg-positive was 98.8% (338/342). Mother to children transmission of HBV at 18 months was 1.0% (1/97). Conclusion: No significant differences in growth development and disease prevalence were found among children born to HBsAg-positive women and women without HBV infection.

Comparison of Nitrosospira strains isolated from terrestrial environments

Most of our knowledge about the physiology of ammonia-oxidizing bacteria is based on experiments with Nitrosomonas europaea, which appears to be less ubiquitous than Nitrosospira. We have isolated Nitrosospiras from widely different environments and compared their specific growth rate, substrate affinity, urease activity, temperature response, pH tolerance and cell morphology. Two of the strains had a variable morphology: the spirals were less tightly coiled than the classical Nitrosospira type and a fraction of the culture had a vibrioid appearance. These vibrioid strains were also peculiar in having a much higher apparent activation energy for ammonia monooxygenase (AMO) (129 and 151 kJ mol(-1)) than that of the more classical Nitrosospiras (78 and 79 kJ mol(-1)). The differences in morphology and activation energy were congruent with the phylogeny of the genes for 16S rRNA (Utåker et al., System. Appl. Microbiol. 18) and AMO. The response to pH in the medium was investigated for four strains. The oxidation rate at the onset of the pH exposure experiment was found to obey classical steady state enzyme kinetics, assuming that NH(3) (not NH(4)(+)) is the rate-limiting substrate. The calculated half saturation constants (K(s)) for AMO were 6-11 µM NH(3). Growth had a narrower pH range than oxidation activity and appeared to be restricted by pH-dependent factors other than NH(3). All the isolated strains were urease positive, with a specific urease activity ranging from 60 to 158% of their specific AMO activity. The urease activity was unaffected by acetylene inhibition of the energy metabolism. The substrate affinity for one strain was found to be around 670 µM.

Nitrous oxide production and methane oxidation by different ammonia-oxidizing bacteria

Ammonia-oxidizing bacteria (AOB) are thought to contribute significantly to N2O production and methane oxidation in soils. Most of our knowledge derives from experiments with Nitrosomonas europaea, which appears to be of minor importance in most soils compared to Nitrosospira spp. We have conducted a comparative study of levels of aerobic N2O production in six phylogenetically different Nitrosospira strains newly isolated from soils and in two N. europaea and Nitrosospira multiformis type strains. The fraction of oxidized ammonium released as N2O during aerobic growth was remarkably constant (0.07 to 0.1%) for all the Nitrosospira strains, irrespective of the substrate supply (urea versus ammonium), the pH, or substrate limitation. N. europaea and Nitrosospira multiformis released similar fractions of N2O when they were supplied with ample amounts of substrates, but the fractions rose sharply (to 1 to 5%) when they were restricted by a low pH or substrate limitation. Phosphate buffer (versus HEPES) doubled the N2O release for all types of AOB. No detectable oxidation of atmospheric methane was detected. Calculations based on detection limits as well as data in the literature on CH4 oxidation by AOB bacteria prove that none of the tested strains contribute significantly to the oxidation of atmospheric CH4 in soils.