Identification and molecular cloning of novel antimicrobial peptides from skin secretions of Odorrana versabilis and Rana palustris

Objective: Amphibian skin secretions are an abundant source of bioactive peptides, some of which could be developed as candidate drugs. Among these natural peptides, cytolytic peptides have attracted the most attention given that they might replace conventional antibiotics and help deal with the problem of microbial resistance. This study discovered two bioactive peptides, Brevinin-1-PLr and Nigrocin-2-OV, from two species frogs, the Chinese bamboo leaf odorous frog (Odorrana versabilis) and the North American pickerel frog (Rana palustris), respectively. Their antimicrobial, anticancer and hemolytic activities were also investigated. Methods: cDNA sequences encoding peptides were cloned from cDNA libraries constructed from the lyophilized secretions of the Chinese bamboo leaf odorous frog and the North American pickerel frog. By reversed-phase HPLC and MS/MS fragmentation sequencing, the encoded novel peptides, named Nigrocin-2-OV and Brevinin-1-PLr, were identified in skin secretions and their structures were confirmed. Replicates of both peptides were produced through solid phase peptide synthesis. Their antimicrobial and anticancer activity was studied against three types of microorganisms (Staphylococcus aureus, Candida albicans, and Escherichia coli) and five cancer cell lines (NCI-H157, PC-3, MDA-MB-435s, MCF-7, and U251MG). Their hemolytic activity was investigated using whole horse blood. Results: In this research, cDNA sequences encoding two novel 24-mer peptides were cloned from cDNA libraries constructed from the lyophilized skin secretions of the Chinese bamboo leaf odorous frog and the North American pickerel frog. Both of the peptides had the strongest inhibitory effect against C. albicans, and IC50 values against five cancer cell lines were all under 6 μM. Conclusions: Nigrocin-2-OV and Brevinin-1-PLr had the strong ability to inhibit the proliferation of studied microorganisms and tumor cell lines, with slight hemolytic activity. Compared with Brevinin-1-PLr, Nigrocin-2-OV exhibited higher antimicrobial and anticancer activity but slightly higher hemolytic activity

Study on the Effect of Fracturing Pump Start and Stop on Tubing Fluid-Structure Interaction Vibration in HPHT Wells via MOC

The processes of HTHP well fracturing, oil drive, and gas recovery are accompanied by the non-stationary flow of medium in the tubing, which may lead to periodic vibration and cause the failure and fatigue of the tubing, thread leakage, and bending deformation. In this paper, a fluid–structure interaction model with 4-equation was established, which considered the unsteady flow of fluid and the motion state of tubing during the periodic injection, pump start, and shutdown of fluid in the tubing. Further, the discrete solution of MOC was used to obtain the variation of fluid flow rate and pressure, tubing vibration rate, frequency, and additional stress with time. The resonance construction parameters corresponding to different tubing diameters were analyzed by discussing the effects of different start and shutdown times as well as pressure on the tubing vibration parameters. The results show that under the periodic injection condition, increasing the tubing diameter or start inside pressure would lead to a sharp increase in the axial additional stress of the tubing generated by fluid–structure interaction, which is not conducive to the safety protection of the tubing. When the pump was shutdown, excessively short operation times and high pressure in the tubing would lead to excessive transient loads in addition to resonance, which would cause damage to the pipeline. Finally, corresponding to the above analysis results, this paper proposes the optimal injection parameters to avoid the generation of resonance, which provides a theoretical basis and reference range for the safe service conditions of the tubing

Study on the Effect of Fracturing Pump Start and Stop on Tubing Fluid-Structure Interaction Vibration in HPHT Wells via MOC

The processes of HTHP well fracturing, oil drive, and gas recovery are accompanied by the non-stationary flow of medium in the tubing, which may lead to periodic vibration and cause the failure and fatigue of the tubing, thread leakage, and bending deformation. In this paper, a fluid–structure interaction model with 4-equation was established, which considered the unsteady flow of fluid and the motion state of tubing during the periodic injection, pump start, and shutdown of fluid in the tubing. Further, the discrete solution of MOC was used to obtain the variation of fluid flow rate and pressure, tubing vibration rate, frequency, and additional stress with time. The resonance construction parameters corresponding to different tubing diameters were analyzed by discussing the effects of different start and shutdown times as well as pressure on the tubing vibration parameters. The results show that under the periodic injection condition, increasing the tubing diameter or start inside pressure would lead to a sharp increase in the axial additional stress of the tubing generated by fluid–structure interaction, which is not conducive to the safety protection of the tubing. When the pump was shutdown, excessively short operation times and high pressure in the tubing would lead to excessive transient loads in addition to resonance, which would cause damage to the pipeline. Finally, corresponding to the above analysis results, this paper proposes the optimal injection parameters to avoid the generation of resonance, which provides a theoretical basis and reference range for the safe service conditions of the tubing

Relationship between Illness Perception and Depressive Symptoms among Type 2 Diabetes Mellitus Patients in China: A Mediating Role of Coping Style

Objective. The aims of the present study were to investigate the prevalence of depressive symptoms among type 2 diabetes mellitus (T2DM) patients in China and to explore how coping style influences the relationship between illness perception and depressive symptoms. Methods. Nine hundred and thirty-nine T2DM patients were recruited from a grade 3 Class A hospital in Harbin, China, and asked to complete a demographic questionnaire as well as the Self-rating Depression Scale (SDS), Brief Illness Perception Questionnaire-Revised (IPQ-R), and Medical Coping Modes Questionnaire (MCMQ). Hierarchical linear regression analysis and the bootstrap method were preformed to examine if coping style influenced the relationship between illness perception and depression. Results. The majority of patients (73.59%) exhibited depressive symptoms, including 37.27% with moderate and 6.71% with severe depressive symptoms. Depressive symptoms were more frequent in patients with complications (P<0.05). A resignation coping style partially mediated the influence of illness perception on depressive symptoms. Conclusions. Interventions to improve coping style may reduce the prevalence or severity of depressive symptoms among T2DM patients, potentially enhancing treatment adherence and clinical outcome

Reliability and validity of a questionnaire measuring knowledge, attitude and practice regarding “oil, salt and sugar” among canteen staff

Abstract Excessive intake of oil, salt and sugar is closely associated with the prevalence of non-communicable chronic diseases (NCDs). Canteen staff’s knowledge, attitude and practice (KAP) about oil, salt and sugar directly affect the content in dishes and the consumers’ intake. However, no valid questionnaire is used to assess KAP among canteen staff about the “oil, salt and sugar”. Therefore, the present study aimed to establish and validate a questionnaire to evaluate the KAP of canteen staff about the “oil, salt and sugar”. This cross-sectional study was conducted among canteen staff randomly selected from three college canteens. Participants completed the questionnaire and retested it two weeks later. Internal and test–retest reliability were assessed using Cronbach’s α and Pearson correlation coefficients, respectively. Validity was assessed using the exploratory factor analysis. 100 participants finished the questionnaire, of which 66% were females with a mean age of 40.3 ± 10.5 years. The Cronbach’s α coefficients of the total questionnaire and Knowledge, Attitude and Practice dimensions were 0.822, 0.830, 0.752 and 0.700, respectively. The test–retest reliability coefficient was 0.968. In exploratory factor analysis, nine common factors were extracted, with 26 items, and the cumulative contribution rate was 70.9%. The questionnaire had a satisfactory property for measuring the KAP of the “oil, salt and sugar” among canteen staff in China

Unraveling shared risk factors for diabetic foot ulcer: a comprehensive Mendelian randomization analysis

Introduction Diabetic foot ulcer (DFU) stands as a severe diabetic lower extremity complication, characterized by high amputation rates, mortality, and economic burden. We propose using Mendelian randomization studies to explore shared and distinct risk factors for diabetic lower extremity complications.Research design and methods We selected uncorrelated genetic variants associated with 85 phenotypes in five categories at the genome-wide significance level as instrumental variables. Genetic associations with DFU, diabetic polyneuropathy (DPN), and diabetic peripheral artery disease (DPAD) were obtained from the FinnGen and UK Biobank studies.Results Body mass index (BMI) emerged as the only significant risk factor for DPAD, DPN, and DFU, independent of type 2 diabetes, fasting glucose, fasting insulin, and HbA1c. Educational attainment stood out as the sole significant protective factor against DPAD, DPN, and DFU. Glycemic traits below the type 2 diabetes diagnosis threshold showed associations with DPAD and DPN. While smoking history exhibited suggestive associations with DFU, indicators of poor nutrition, particularly total protein, mean corpuscular hemoglobin, and mean corpuscular volume, may also signal potential DFU occurrence.Conclusions Enhanced glycemic control and foot care are essential for the diabetic population with high BMI, limited education, smoking history, and indicators of poor nutrition. By focusing on these specific risk factors, healthcare interventions can be better tailored to prevent and manage DFU effectively

Fracture analysis and countermeasures of the grid switch castings

Based on the detection technology of direct reading spectrum, metallographic microscope and X-ray, the defects of the grid switch castings were analyzed. The four main forms of casting fracture were summarized as poor physical and chemical properties, material misuse, casting defects and designing defects. In order to strengthen the quality control of the source of the product, it was proposed to carry out targeted network inspection in the two stages of material arrival and infrastructure acceptance

Methane concentrations and aerobic methane oxidation rates in the East China Sea and Yellow Sea

We measured the methane concentrations and aerobic methane oxidation rates (MOx) in the seawater of East China Sea and Yellow Sea. Seawater samples were collected onboard "Dong Fang Hong 3" in April 2021 using a rosette system equipped with 24-liter Niskin bottles and a Seabird 911 CTD. Methane concentrations were measured using a purge-and-trap preconcentration method with a gas chromatography (Shimadzu GC-2014B) with a flame ionization detector. The rate constants of MOx and MOx rates were determined using a radiotracer approach through quantifying the conversion of added 3H-methane tracer to the oxidation product 3H-H2O

Methanol distribution and metabolic rate in the northwest Pacific Ocean in May/June 2021

We investigated the seawater methanol abundance, the dynamic of microbial methanol (MeOH) metabolism and the geochemical parameters in the northwest Pacific Ocean (NWPO) area. Seawater samples were collected during May-June 2021 aboard the R/V “Dongfanghong 3” in the northwest Pacific Ocean. Seawater was sampled using a Seabird 911 CTD-Niskin rosette system equipped with conductivity, temperature and depth sensors. Methanol samples were collected directly without filters and then stored at -80℃ for laboratory analysis. Methanol concentrations were determined by a modified commercial purge and trap system combined with Agilent GC-8890 gas chromatograph with a flame ionization detector. Microbial methanol assimilation and oxidation rates were determined by quantifying 14C-MeOH incorporation into biomass and oxidation to CO2 (Zhuang et al., 2018). Nutrients were measured using Seal Analytical Quaatro nutrient autoanalyzer except for ammonium which was analyzed by a fluorometric method on board (Ning et al., 2013). Chlorophyll-a was measured by fluorometric method (Parsons et al., 1984)