[Determination of 14 volatile organic compounds in urine by headspace gas chromatography-mass spectrometry].

Objective: To establish a automatic headspace gas chromatography-mass spectrometry (HS/GC-MS) method for the determination of 14 volatile organic compounds in urine. Methods: In September 2022, 10 ml urine sample was taken into a 20 ml headspace bottle, balanced for 30 min at 65 ℃, and then detected by HS/GC-MS and quantified by external standard method. Results: The 14 volatile organic compounds showed good linearity at 0.2-8.0 µg/L and 0.1-4.0 µg/L, with correlation coefficients ranging from 0.9956-0.9999. The recoveries were 79.8%-113.1% with relative standard deviations 0.05%-0.27% when three different concentration levels were added. Detection limit was 0.03-0.05 µg/L. Conclusion: The method is simple and convenient, and the recovery and precision meet the requirements. It can be used for the determination of common volatile organic compounds in urine.

Effect of mechanical ventilation guided by transpulmonary pressure in acute respiratory distress syndrome patients: a systematic review and meta-analysis of randomized control trials.

OBJECTIVE: This study aimed to investigate the effect of mechanical ventilation guided by transpulmonary pressure in patients diagnosed with acute respiratory distress syndrome (ARDS). MATERIALS AND METHODS: Randomized control trials of ARDS patients that received mechanical ventilation guided by transpulmonary pressure vs. mechanical ventilation guided by traditional lung protective ventilation strategies in adults were retrieved by two reviewers independently from PubMed, EMBASE, The Cochrane Library, The China National Knowledge Infrastructure, and WanFang database before October 2022. The protocol has been registered on PROSPERO (CRD42022307816). The primary outcome was mortality. The secondary outcomes included mechanical ventilation days, oxygenation function and ventilation parameters, hemodynamics, and cytokines level. RESULTS: Thirteen articles (819 patients) were finally included through our search strategy. The total mortality (RR, 0.68; 95% CI, 0.54-0.85; p = 0.0006) and mechanical ventilation days (MD, -2.77; 95% CI, -4.60 - -0.94; p = 0.003) reduced when compared with the control group. Patients in the transpulmonary pressure group had higher oxygen index (MD, 40.74; 95% CI 9.81-71.68, p = 0.010) and lung compliance (MD, 7.98; 95% CI 4.55-11.41, p < 0.00001). Positive end-expiratory pressure (PEEP) was higher in the transpulmonary pressure group (MD, 5.47; 95% CI, 3.59 - 7.35; p < 0.00001). The Interlukin-6 (IL-6) level in the control group decreased obviously compared with that in the transpulmonary pressure group (SMD, -2.03; 95% CI, -3.50 - -0.56; p = 0.007). CONCLUSIONS: Mechanical ventilation guided by transpulmonary pressure tended to have a beneficial prognosis on ARDS patients. Oxygenation and lung mechanics parameters were also improved. The clinical effect of mechanical ventilation directed by transpulmonary pressure was superior to the traditional lung protective ventilation strategies in ARDS patients.

The effect of driving pressure-guided ventilation strategy on the patients with mechanical ventilation: a meta-analysis of randomized controlled trials.

OBJECTIVE: The aim of this study was to evaluate the effect of driving pressure (DP) guided ventilation strategy on the patients with mechanical ventilation in the hospital. MATERIALS AND METHODS: The articles published in PubMed, the Cochrane Library, the China National Knowledge Information (CNKI), Wei Pu, Wan Fang database and Web of Science from inception to September 2021 were retrieved. The Q test and the I² statistic were used to assess statistical heterogeneity. Risks ratios (RR) with 95% confidence intervals (CI) were calculated for mortality. RESULTS: Seven studies (n=1,405 patients) were included. Five studies reported an adjusted Risk Ratio (RR) of mortality. Compared with the control group, the DP guided ventilation group was associated with a decreased mortality (RR 0.56; 95% confidence interval [CI], 0.39-0.79; p=0.001; I2 = 23%) using a fixed-effects model without significant heterogeneity. The control group had significantly higher driving pressure level than DP guided group (MD -3.03, 95%CI, -5.72 - -0.34, I2=100%, p=0.03); PaO2/FiO2 was significantly higher in DP guided group than in control group (MD 43.37; 95%CI, 12.58-74.15; I2=97%, p=0.006). There was no statistically significant difference in respiratory compliance, complications, platform pressure, duration of mechanical ventilation and the length of hospital stay between the DP guided group and the control group. CONCLUSIONS: The results suggested that the driving pressure guided ventilation strategy could decrease the mortality and increase oxygenation index (OI). However, further high-quality randomized controlled trials (RCTs) are needed to verify the impact of driving pressure on mechanically ventilated patients.

Association of A-20C polymorphism in the angiotensinogen gene with essential hypertension: a meta-analysis.

The A-20C polymorphism in the angiotensinogen (AGT) gene has been associated with increased risk of essential hypertension in several studies; however, these studies gave inconsistent results. In this study, we performed a meta-analysis to assess the association between AGT A-20C polymorphism and essential hypertension. Published literature was retrieved from PubMed. Pooled odd's ratio (OR) with 95% confidence interval (CI) was calculated using fixed- or random-effect models. A total of 10 case-control studies containing 3653 cases and 3457 controls were enrolled to this meta-analysis. In a combined analysis, the results showed a significant association between the AGT A-20C polymorphism and risk of essential hypertension (AA vs CC: OR = 0.62, 95%CI = 0.46-0.84; recessive model: OR = 0.66, 95%CI = 0.49-0.88). In the subgroup analysis stratified by race, significant associations were found between the AGT A-20C polymorphism and essential hypertension risk in Asians (AA vs CC: OR = 0.59, 95%CI = 0.43-0.80; recessive model: OR = 0.63, 95%CI = 0.46-0.85). In conclusion, the results of this meta-analysis suggested that the AGT A-20C polymorphism was associated with risk of essential hypertension in Asians.

Identification and characterization of RFRP gene in pigs and its association with reproductive traits.

RFamide-related peptide (RFRP) gene is a crucial gene of the hypothalamo-pituitary-gonadal axis and plays an important role in reproduction regulation. This study aimed to clone and characterize the pig RFRP gene. We obtained a 645-bp cDNA of pig RFRP gene comprising a 546-bp open reading frame, which encoded a peptide of 188 amino acids. The pig RFRP coding sequences have the identities of 81, 68.8, and 76.1% with their counterparts in humans, mice, and rats, respectively. Real-time polymerase chain reaction showed that the pig RFRP gene was expressed predominantly in the stomach and testis of males, and large intestine and uterus of females. It was also found to be abundantly expressed in the cerebrum and liver tissues of both male and female pigs. The pig RFRP gene is 4.6 kb long and contains 3 exons and 2 introns. We further identified a total of 25 single nucleotide polymorphisms and 2 insertion/deletion (indel) polymorphisms across the whole RFRP gene, and 9 of them were in the exons. Marker trait association analysis in Yorkshire and Landrace populations showed that g.45859759C>T was significantly associated with the total number born of second parity (TBA2; P < 0.05). In conclusion, the pig RFRP gene was cloned and characterized in this study, and its polymorphism g.45859759C>T showed significant associations with reproductive traits.

Characterization of chicken natural resistance-associated macrophage protein encoding genes (Nramp1 and Nramp2) and association with salmonellosis resistance.

Natural resistance-associated macrophage protein 1 and 2 encoding genes (Nramp1 and Nramp2) are related to many diseases. We cloned the cDNA of chicken Nramp1 and Nramp2 genes, characterized their expression and polymorphisms, and investigated the association of some SNPs with resistance to salmonellosis. The Nramp1 cDNA was 1746 bp long and the Nramp2 cDNA was 1938 bp long. These cDNAs are similar to previously reported cDNAs, varying by two and one amino acids, respectively. The chicken Nramp1 gene expressed predominantly in liver, thymus and spleen in both females and males. The Nramp2 gene expressed in almost all tissues, but predominantly in breast muscle, leg muscle, cerebrum, cerebellum, lung, kidney, and heart in both females and males. We identified 45 SNPs and 2 indels in the chicken Nramp1 gene; three of 13 SNPs in the exons were missense mutations (Arg223Gln, Ala273Glu and Arg497Gln). Association analysis indicated that A24101991G is significantly associated with chicken salmonellosis resistance. These results will be useful for functional investigation of chicken Nramp1 and Nramp2 genes.

Molecular cloning, expression and variation analyses of the dopamine D2 receptor gene in pig breeds in China.

The dopamine D2 receptor (DRD2) is a crucial mediator for normal physiological processes. We cloned the pig DRD2 gene, investigated its distribution in tissues and identified polymorphisms by RT-PCR, quantitative real-time PCR and direct sequencing. Two Yorkshire pigs from Guangdong Academy of Agricultural Sciences (Guangzhou, China) were selected to clone the gene and investigate its expression; 16 individuals from four pig breeds (Yorkshire, Landrace, small-ear spotted, and Xinchang) were used to scan the variations. The two transcripts (DRD2L and DRD2S), obtained through insertion or deletion of exon 5 and part of 3'UTR, were found to encode 444- and 415-amino acid proteins, respectively. The 574-bp indel in 3'UTR comprises five miRNA targeting sites, based on bioinformatics predictions. The pig DRD2 gene expresses predominantly in the pituitary gland, and then in oviducts and the hypothalamus. Both DRD2L and DRD2S mRNA were detected in cerebrum, cerebellum, hypothalamus, pituitary gland, back muscle, oviduct, uterus, and testis tissues; DRD2L was more abundant than DRD2S. The DRD2 gene is located on chromosome 9 and contains seven exons. Sixty-one different sequences were identified in this gene; among seven in the coding region, only one altered the encoded amino acid. These findings will help us understand the functions of the DRD2 gene in pigs.

Polymorphisms associated with egg number at 300 days of age in chickens.

We looked for variations that could be associated with chicken egg number at 300 days of age (EN300) in seven genes of the hypothalamic-pituitary-gonadal axis, including gonadotrophin-releasing hormone-I (GnRH-I), GnRH receptor (GnRHR), neuropeptide Y (NPY), dopamine D2 receptor (DRD2), vasoactive intestinal polypeptide (VIP), VIP receptor-1 (VIPR-1), prolactin (PRL), and the QTL region between 87 and 105 cM of the Z chromosome. Ten mutations in the seven genes were chosen to do marker-trait association analyses in a population comprising 1310 chickens, which were obtained from a company located in Guangdong Province of China. The C1704887T of VIPR-1 was found to have a highly significant association with EN300. The T5841629C of DRD2 and the C1715301T of VIPR-1 were significantly associated with EN300. A highly significant association was also found between the C1704887T-C1715301T haplotypes of VIPR-1 and EN300. H1H3 had the highest EN300. Four PCR-RFLP variations in the candidate QTL region were selected to investigate their genetic effects on EN300. The haplotypes of T32742468C-G32742603A in this region showed a highly significant association with EN300. Bioinformatics analyses showed that both T32742468C and G32742603A were located in intron 1 of the SH3-domain GRB2-like 2 (SH3GL2) gene. We conclude that five SNPs, including C1704887T and C1715301T of VIPR-1, T5841629C of DRD2, and T32742468C and G32742603A of SH3GL2, would be useful as markers for breeding to increase chicken EN300.

Thermal degradation mechanisms of wood under inert and oxidative environments using DAEM methods.

The pyrolytic behavior of wood is investigated under inert and oxidative conditions. The TGA experiment is given a temperature variation from 323 to 1173 K by setting the heating rate between 5 and 40 K/min. The results of DTG curves show that the hemicellulose shoulder peak for birch is more visible under inert atmosphere due to the higher content of reactive xylan-based hemicellulose (mannan-based for pine). When oxygen presents, thermal reactivity of biomass (especially the cellulose) is greatly enhanced due to the acceleration of mass loss in the first stage, and complex reactions occur simultaneously in the second stage when char and lignin oxidize. A new kinetic model is employed for biomass pyrolysis, namely the distributed activation energy model (DAEM). Under inert atmosphere, the distributed activation energy for the two species is found to be increased from 180 to 220 kJ/mol at the solid conversion of 10-85% with the high correlation coefficient. Under oxidative atmosphere, the distributed activation energy is about 175-235 kJ/mol at the solid conversion of 10-65% and 300-770 kJ/mol at the solid conversion of 70-95% with the low correlation coefficient (below 0.90). Comparatively, the activation energy obtained from established global kinetic model is correspondingly lower than that from DAEM under both inert and oxidative environments, giving relatively higher correlation coefficient (more than 0.96). The results imply that the DAEM is not suitable for oxidative pyrolysis of biomass (especially for the second mass loss stage in air), but it could represent the intrinsic mechanism of thermal decomposition of wood under nitrogen better than global kinetic model when it is applicable.

Associations of ATGL gene polymorphisms with chicken growth and fat traits.

Adipose triglyceride lipase (ATGL) catalyses the initial step in triglyceride hydrolysis, so the ATGL gene is a candidate for growth and fat traits in chickens. Nine reported single-nucleotide polymorphisms (SNPs) located in 3 exons of the chicken ATGL gene were chosen for genotyping an F2 population. Only 5 SNPs were confirmed for polymorphisms and used for association analyses. The results show that c.531G>A (p.E177Syn) was not associated with any growth and fat traits (P > 0.05), but c.782G>A (p.S261N) was associated with body weight (BW) on days 14, 21, 35, 63, 70, 77, cingulated fat width and abdominal fat pad weight (P < 0.05), and significantly associated with BW on days 42, 49, and 56 (P < 0.01). Significant associations of c.903C>T (p.F301Syn) with BW on days 49 and 77 days and crude protein content of breast muscle (P < 0.05), and c.1164G>A (p.K388Syn) with BW on day 7 (P < 0.05) were also detected. Additionally, c.1069T>C (p.L357Syn) was associated with breast muscle colour (P < 0.05), and significantly associated with crude fat (ether extract) content of breast muscle (P < 0.01). Thus the missense SNP of c.782G>A (p.S261N) was significantly associated with the largest number of chicken growth and fat traits in this study.

The pyrolytic degradation of wood-derived lignin from pulping process.

Lignin is a key component in the biomass with a complex polymeric structure of the phenyl-C(3) alkyl units. The kraft lignin from the wood pulping process is tested in TG-FTIR and Py-GC-MS. The samples are pyrolyzed in TGA coupled with FTIR from 30 to 900 degrees C at the heating rate of 20 and 40K/min. The evolution of phenolic compounds in the initial pyrolysis stage of lignin is determined by FTIR, while the second stage is mainly attributed to the production of the low molecular weight species. A bench-scale fast pyrolysis unit is employed to investigate the effect of temperature on the product yield and composition. It is found that the guaiacol-type and syringol-type compounds as the primary products of lignin pyrolysis are predominant in bio-oil, acting as the significant precursors for the formation of the derivatives such as the phenol-, cresol- and catechol-types. A series of free-radical chain-reactions, concerning the cracking of different side-chain structures and the methoxy groups on aromatic ring, are proposed to demonstrate the formation pathways for the typical compounds in bio-oil by closely relating lignin structure to the pyrolytic mechanisms. The methoxy group (-OCH(3)) is suggested to work as an important source for the formation of the small volatile species (CO, CO(2) and CH(4)) through the relevant free radical coupling reactions.