Identification of characteristic aroma compounds in chicken meat and their metabolic mechanisms using gas chromatography-olfactometry, odor activity values, and metabolomics.

Aroma has an important influence on the aroma quality of chicken meat. This study aimed to identify the characteristic aroma substances in chicken meat and elucidate their metabolic mechanisms. Using gas chromatography-olfactometry and odor activity values, we identified nonanal, octanal, and dimethyl tetrasulfide as the basic characteristic aroma compounds in chicken meat, present in several breeds. Hexanal, 1-octen-3-ol, (E)-2-nonenal, heptanal, and (E,E)-2,4-decadienal were breed-specific aroma compounds found in native Chinese chickens but not in the meat of white-feathered broilers. Metabolomics analysis showed that L-glutamine was an important metabolic marker of nonanal, hexanal, heptanal, octanal, and 1-octen-3-ol. Exogenous supplementation experiments found that L-glutamine increased the content of D-glucosamine-6-P and induced the degradation of L-proline, L-arginine, and L-lysine to enhance the Maillard reaction and promote the formation of nonanal, hexanal, heptanal, octanal, and 1-octen-3-ol, thus improving the aroma profile of chicken meat.

Benefits of combination therapy with immune checkpoint inhibitors and predictive role of tumour mutation burden in hepatocellular carcinoma: A systematic review and meta-analysis.

OBJECTIVES: To investigate the clinical benefits of combination therapy with immune checkpoint inhibitors (ICIs) and best combination regimen for people with advanced hepatocellular carcinoma (HCC) and to explore the predictive performance of tumour mutation burden (TMB). METHODS: We conducted a systematic literature search to identify clinical trials. Meta-analysis and subgroup analyses were performed to estimate the benefits of combination regimens with PD-1/PD-L1 inhibitors for patients with advanced HCC and compare the effectiveness of PD-1/PD-L1 inhibitors and sorafenib as first-line therapy. Individualized analysis and Kaplan-Meier were used to assess the prognostic value of TMB. RESULTS: A total of 29 studies with 5396 patients were included. ICIs' combination therapy had higher ORR (26 % vs 15 %) and DCR (73 % vs 55 %), longer PFS (5.5 vs 3.1 months) and OS (15.9 vs 12.6 months) compared to monotherapy. Anti-PD-1/PD-L1 agents provided improved ORR, DCR, PFS and OS compared to sorafenib. The overall ORs of ORR and DCR in subgroup analysis were 3.49 (95 % CI 2.36-5.17, p < 0.01) and 1.60 (95 % CI 1.15-2.21, p < 0.01). The overall HRs of PFS and OS were 0.68 (95 % CI 0.48-0.96, p = 0.03) and 0.73 (95 % CI 0.62-0.85, p < 0.01). PD-1/PD-L1 inhibitors plus anti-VEGF agents had an advantage in DCR (0.80 vs 0.48, meta-regression =  - 0.32, P < 0.001), but an equal ORR (0.29 vs 0.26) compared to dual immune checkpoint inhibitors. The total OS in Dua-ICIs were 16.5 months (95 % CI 14.2-18.7), yet not reached in the major studies of ICI plus anti-VEGF regimen. In individualized analysis, the 1-year OS was superior for patients who had high-TMB (>10, mutations/Mb) than moderate-TMB (1-10, mutations/Mb; 28 % vs 15 %, P = 0.025). CONCLUSION: Immune checkpoint inhibitors' combination therapy improved clinical outcomes in the management of advanced hepatocellular carcinoma. However, the overall objective response rate still did not exceed 30%. PD-1/PD-L1 inhibitors plus anti-angiogenic agents and dual immunotherapy provided significantly increased survival over sorafenib, which also pose new challenges for future research, and more appropriate and guided control regimens are required. Also, TMB may be a promising prognostic biomarker for immunotherapy in HCC. However, the validation of prospective and large sample studies is needed.

Transcriptomic Analysis of Laying Hens Revealed the Role of Aging-Related Genes during Forced Molting.

Molting in birds provides us with an ideal genetic model for understanding aging and rejuvenation since birds present younger characteristics for reproduction and appearance after molting. Forced molting (FM) by fasting in chickens causes aging of their reproductive system and then promotes cell redevelopment by providing water and feed again. To reveal the genetic mechanism of rejuvenation, we detected blood hormone indexes and gene expression levels in the hypothalamus and ovary of hens from five different periods during FM. Three hormones were identified as participating in FM. Furthermore, the variation trends of gene expression levels in the hypothalamus and ovary at five different stages were found to be basically similar using transcriptome analysis. Among them, 45 genes were found to regulate cell aging during fasting stress and 12 genes were found to promote cell development during the recovery period in the hypothalamus. In addition, five hub genes (INO80D, HELZ, AGO4, ROCK2, and RFX7) were identified by WGCNA. FM can restart the reproductive function of aged hens by regulating expression levels of genes associated with aging and development. Our study not only enriches the theoretical basis of FM but also provides insights for the study of antiaging in humans and the conception mechanism in elderly women.

Understanding Transcriptomic and Serological Differences between Forced Molting and Natural Molting in Laying Hens.

Molting is natural adaptation to climate change in all birds, including chickens. Forced molting (FM) can rejuvenate and reactivate the reproductive potential of aged hens, but the effect of natural molting (NM) on older chickens is not clear. To explore why FM has a dramatically different effect on chickens compared with NM, the transcriptome analyses of the hypothalamus and ovary in forced molted and natural molted hens at two periods with feathers fallen and regrown were performed. Additionally, each experimental chicken was tested for serological indices. The results of serological indices showed that growth hormone, thyroid stimulating hormone, and thyroxine levels were significantly higher (p < 0.05) in forced molted hens than in natural molted hens, and calcitonin concentrations were lower in the forced molted than in the natural molted hens. Furthermore, the transcriptomic analysis revealed a large number of genes related to disease resistance and anti-aging in the two different FM and NM periods. These regulatory genes and serological indices promote reproductive function during FM. This study systematically revealed the transcriptomic and serological differences between FM and NM, which could broaden our understanding of aging, rejuvenation, egg production, and welfare issues related to FM in chickens.

Separation of Uranium and Thorium for 230Th-U Dating of Submarine Hydrothermal Sulfides.

The age of a submarine hydrothermal sulfide is a significant index for estimating the size of hydrothermal ore deposits. Uranium and thorium isotopes in the samples can be separated for 230Th-U dating. This article presents a method to purify and separate U and Th isotopes in submarine hydrothermal sulfide samples. Following this technique, the separated U and Th fractions can meet measuring requirements by multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS). The age of the hydrothermal sulfide sample can be calculated by measuring the present-day activity ratios of 230Th/238U and 234U/238U. A super clean room is necessary for this experiment. Cleaned regents and supplies are used to reduce the contamination during the sample processes. Balance, hotplate, and centrifuge are also used. The sulfide sample is powdered for analysis and less than 0.2 g sample is used. Briefly, the sample is weighed, dissolved, added to 229Th-233U-236U double spike solution, Fe co-precipitated, and separated on an anion-exchange resin extraction column. Approximately 50 ng U is consumed for 230Th-U dating of sulfides sample by MC-ICPMS.