Clinical features and mutation analysis of class 1/2/3 BRAF mutation colorectal cancer.

BACKGROUND: BRAF (B-Raf proto-oncogene, serine/threonine kinase)-mutated colorectal cancer (CRC) still has poor prognostic. The efficacy of BRAF inhibitor is unpredictable just that intrinsic genetic complexity, immune microenvironment and partially unknown reason. Understanding the co-mutation mechanism can help improve treatment and follow-up strategies. METHODS: We retrospectively analyzed 35 (BRAF-mutated/BRAF wild-type) Chinese CRC and 125 Western CRC who underwent next-generation sequencing (NGS). Co-occurrence mutation analysis, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis was enabled in this study. RESULTS: Thirty-five (10.32%) patients were BRAF-mutated, with 17 patients were BRAF V600E in Beijing Hospital. Patients with BRAF mutation had significant association with high tumor mutational burden (TMB-H) (P=0.0004) and high microsatellite instability (MSI-H) (P=0.0003) than those with BRAF wild-type. In 125 BRAF-mutated Western CRC patients, the frequency of age at diagnosis, gender, sample type, Tumor-Node-Metastasis (TNM), MSI, TMB, and BRAF mutation type was consistent with Chinese data. However, the primary tumor location showed significant statistical differences (P<0.0001). Class 1 were more likely to occur in elder and female. Western cohort was consistent with above in Chinese cohort. Other clinicopathological features were not significantly associated with mutation type. However, Western cohort showed class 1 exhibited primary sample type predominance in both class 1 vs. others (P<0.05) and class 1 vs. class 3 (P<0.05). Meanwhile, the data showed TMB-H (57.69% vs. 11.76%, P<0.001) and MSI-H (28.21% vs. 0%, P<0.05) of the class 1 BRAF mutation proportion were significantly higher, compared with class 3 BRAF mutation. In concurrent oncogenic mutations, compared with non-class 1 BRAF mutation, class 1 are more likely to co-occur with passenger mutation. Data from Western populations showed similar results. We also found that the class 1 mutation was mutually exclusive with co-KRAS (Kirsten rat sarcoma viral oncogene homologue) mutation in CRC, and co-APC (APC regulator of WNT signaling pathway) mutation appeared more frequently in non-class 1 BRAF mutation. KEGG pathway showed that fewer proto-cancer signaling pathways were enriched in the class 1, which further confirmed that this type had stronger tumorigenicity. GO enrichment also proved that class 1 had stronger tumorigenicity. Finally, prognostic analysis showed median overall survival (mOS) of 19.43 months in class 1 vs. 47.57 months in non-class 1 (P=0.0002). Further study showed that the mOS of class 1, class 2, class 3 and class NA (unknown) was 19.43, 28.50, 47.57 months and not reached (P=0.0001), respectively. CONCLUSIONS: This study showed class 1/non-class 1 BRAF mutation in CRC had significantly differences in co-mutation features, genomic markers and prognostic. Understanding BRAF mutation types and co-mutation mechanism will contribute to accurately grasping treatment and follow-up strategies and promoting the development of precision therapy for CRC in the future.

Long-course chemoradiation plus concurrent/sequential PD-1 blockade as neoadjuvant treatment for MMR-status-unscreened locally advanced rectal cancer: protocol of a multicentre, phase 2, randomised controlled trial (the POLAR-STAR trial).

INTRODUCTION: Recent preclinical studies have discovered unique synergism between radiotherapy and immune checkpoint inhibitors, which has already brought significant survival benefit in lung cancer. In locally advanced rectal cancer (LARC), neoadjuvant radiotherapy plus immune checkpoint inhibitors have also achieved surprisingly high pathological complete response (pCR) rates even in proficient mismatch-repair patients. As existing researches are all phase 2, single-cohort trials, we aim to conduct a randomised, controlled trial to further clarify the efficacy and safety of this novel combination therapy. METHODS AND ANALYSIS: Eligible patients with LARC are randomised to three arms (two experiment arms, one control arm). Patients in all arms receive long-course radiotherapy plus concurrent capecitabine as neoadjuvant therapy, as well as radical surgery. Distinguishingly, patients in arm 1 also receive anti-PD-1 (Programmed Death 1) treatment starting at Day 8 of radiation (concurrent plan), and patients in arm 2 receive anti-PD-1 treatment starting 2 weeks after completion of radiation (sequential plan). Tislelizumab (anti-PD-1) is scheduled to be administered at 200 mg each time for three consecutive times, with 3-week intervals. Randomisation is stratified by different participating centres, with a block size of 6. The primary endpoint is pCR rate, and secondary endpoints include neoadjuvant-treatment-related adverse event rate, as well as disease-free and overall survival rates at 2, 3 and 5 years postoperation. Data will be analysed with an intention-to-treat approach. ETHICS AND DISSEMINATION: This protocol has been approved by the institutional ethical committee of Beijing Friendship Hospital (the primary centre) with an identifying serial number of 2022-P2-050-01. Before publication to peer-reviewed journals, data of this research will be stored in a specially developed clinical trial database. TRIAL REGISTRATION NUMBER: NCT05245474.

Synergistic Target of Intratumoral Microbiome and Tumor by Metronidazole-Fluorouridine Nanoparticles.

Clinical and experimental evidence confirmed bacterial infiltration in a variety of tumors, which is related to the progression and therapeutic effects of the tumors. Although the administration of antibiotics inhibits the growth of bacteria inside the tumor, systemic distribution of antibiotics induces an imbalance of other microbiomes in the body, which in turn leads to the development of new diseases. To address this clinical challenge, we nanonized an antibiotic in this study. Metronidazole, an antibiotic against broad anaerobes, was linked to fluorouridine to form an amphiphilic small molecule, metronidazole-fluorouridine, which further autoassembled as metronidazole-fluorouridine nanoparticles (MTI-FDU) in a hydrophilic solution. The disulfide bond in the linker cleaves in response to high levels of glutathione (GSH) in the tumor microenvironment. The synergistic antitumor effect of MTI-FDU was observed in two animal models of gut cancer with intratumoral bacteria. Analysis revealed that metronidazole delivered by nanoparticles attacked bacteria inside the tumor, while it had minimal effect on gut microbial homeostasis. Further experiments at the cellular and molecular levels disclosed that MTI-FDU shaped the tumor immune microenvironment through clearance of bacteria and bacterial products. In conclusion, we achieved a synergistic antitumor effect by a dual target of both the intratumoral microbiome and tumor cells. Antibiotic-composed nanoparticles have a clinical advantage in the treatment of tumors with bacteria infiltration, which kill pro-tumor bacteria efficiently as well as keep a balanced microbiota of the patient.

[Mercury in tree rings: Advances, problems and prospects]. / æ ‘æœ¨å¹´è½®æ±žè®°å½•: 进展、问题和展望.

As a highly biotoxic element, mercury (Hg) can be enriched by the food chain and has negative effect on ecosystems. Changes of Hg flux and reserves in forest have important effects on its biogeochemical cycle in forest ecosystem. Due to limitation of temporal and spatial monitoring, there is not comprehensive understanding on Hg distribution. Widely distributed trees can be used as effective bio-monitors and Hg records in tree rings can be used to study Hg temporal and spatial distribution. Hg accumulated by root, leaf, bark, and other tissues can be detained in bole and record environmental Hg variations. Therefore, historical Hg trends can be restructured by analyzing Hg concentration in tree rings and the biogeochemical characteristics can be understood with Hg isotope ratio. We reviewed the method of measurement of Hg concentration and isotope ratio and application of reconstruction using Hg concentration in tree ring. We suggested the great application potential of Hg isotope ratio in atmospheric Hg construction and biogeochemistry cycle and raised concerns in further studies.

Contrasting growth responses of Qilian juniper (Sabina przewalskii) and Qinghai spruce (Picea crassifolia) to CO2 fertilization despite common water-use efficiency increases at the northeastern Qinghai-Tibetan plateau.

Rising atmospheric carbon dioxide (CO2) may enhance tree growth and mitigate drought impacts through CO2 fertilization. However, multiple studies globally have found that rising CO2 has not translated into greater tree growth despite increases in intrinsic water-use efficiency (iWUE). The underlying mechanism discriminating between these two general responses to CO2 fertilization remains unclear. We used two species with contrasting stomatal regulation, the relatively anisohydric Qilian juniper (Sabina przewalskii) and the relatively isohydric Qinghai spruce (Picea crassifolia), to investigate the long-term tree growth and iWUE responses to climate change and elevated CO2 using tree ring widths and the associated cellulose stable carbon isotope ratios (δ13C). We observed a contrasting growth trend of juniper and spruce with juniper growth increasing while the spruce growth declined. The iWUE of both species increased significantly and with similar amplitude throughout the trees' lifespan, though the relatively anisohydric juniper had higher iWUE than the relatively isohydric spruce throughout the period. Additionally, with rising CO2, the anisohydric juniper became less sensitive to drought, while the relatively isohydric spruce became more sensitive to drought. We hypothesized that rising CO2 benefits relatively anisohydric species more than relatively isohydric species due to greater opportunity to acquire carbon through photosynthesis despite warming and droughts. Our findings suggest the CO2 fertilization effect depends on the isohydric degree, which could be considered in future terrestrial ecosystem models.

Warming and CO2 enrichment modified the ecophysiological responses of Dahurian larch and Mongolia pine during the past century in the permafrost of northeastern China.

Tree-ring δ13C and δ18O of dominant Dahurian larch and Mongolia pine in the permafrost region of the northern Great Higgnan Mountains, China were used to elucidate species-specific ecophysiological responses to warming temperatures and increasing CO2 over the past century. Larch and pine stable carbon discrimination (Δ13C) 13C and δ18O in tree rings both showed synchronous changes during the investigated period (1901-2010), but with species-specific isotopic responses to atmospheric enriched CO2 and warming. Tree-ring Δ13C and δ18O were controlled by both maximum temperature and moisture conditions (precipitation, relative humidity and vapor pressure deficit), but with different growth periods (Δ13C in June-July and δ18O in July-August, respectively). In addition, stable isotopes of larch showed relatively greater sensitivity to moisture deficits than pine. Climatic conditions from 1920 to 1960 strongly and coherently regulated tree-ring Δ13C and δ18O through stomatal conductance. However, climatic-sensitivities of tree-ring Δ13C and δ18O recently diverged, implying substantial adjustments of stomatal conductance, photosynthetic rate and altered water sources over recent decades, which reveal the varied impacts of each factor on tree-ring Δ13C and δ18O over time. Based on expected changes in leaf gas-exchange, we isolated the impacts of atmospheric CO2 and climate change on intrinsic water-use efficiency (iWUE) over the past century. Higher intracellular CO2 in pine than larch from 1960 onwards suggests this species may be more resilient to severe droughts in the future. Our data also illustrated no weakening of the iWUE response to increasing CO2 in trees from this permafrost region. The overall pattern of CO2 enrichment and climate impacts on iWUE of pine and larch were similar, but warming increased iWUE of larch to a greater extent than that of pine over recent two decades. Taken together, our findings highlight the importance of considering how leaf gas-exchange responses to atmospheric CO2 concentration influence species-specific responses to climate and the alteration of the hydrological environment in forests growing in regions historically dominated by permafrost that will be changing rapidly in response to future warming and increased CO2.

The quality of total mesorectal excision specimen: A review of its macroscopic assessment and prognostic significance.

As a surgical procedure which could significantly lower the recurrence rate of cancers, total mesorectal excision (TME) has been the gold standard for middle and lower rectal cancer treatment. However, previous studies have shown that the procedure did not achieve the ideal theoretical local recurrence rates of rectal cancers. Some researchers pointed out it was very likely that not all so-called TME treatments completely removed the mesorectum, implying that some of these TME surgical treatments failed to meet oncological quality standards. Therefore, a suitable assessment tool for the surgical quality of TME is necessary. The notion of "macroscopic assessment of mesorectal excision (MAME)" was put forward by some researchers as a better assessment tool for the surgical quality of TME and has been confirmed by a series of studies. Besides providing rapid and accurate surgical quality feedbacks for surgeons, MAME also effectively assesses the prognosis of patients with rectal cancer. However, as a new assessment tool used for TME surgical quality, MAME has an only limited influence on the current guidelines and is yet to be widely applied in most countries. The aims of this review are to provide a detailed introduction to MAME for clinical practice and to summarize the current prognostic significance of MAME.

Climate signals in tree-ring δ18 O and δ13 C from southeastern Tibet: insights from observations and forward modelling of intra- to interdecadal variability.

Stable isotopes in tree rings are increasingly used as proxies for climatic and ecophysiological changes. However, uncertainties remain about the strength and consistency of their response to environmental variation at different temporal (i.e. seasonal to inter-decadal) scales. We developed 5 yr of intra-seasonal and 62 yr of early- and late-wood δ13 C and δ18 O series of Smith fir (Abies georgei var. smithii) on the southeastern Tibetan Plateau, and used a process-based forward model to examine the relative importance of environmental and physiological controls on the isotopic data. In this temperate high-altitude region, the response, both δ18 O and δ13 C, is primarily to variations in relative humidity, but by different processes. In δ18 O, the response is via source water δ18 O but also arises from leaf water 18 O enrichment. In δ13 C, the response is via changes in stomatal conductance but is modified by carry-over effects from prior periods. We conclude that tree-ring δ18 O may be a more robust climate proxy than δ13 C, and δ13 C may be more suited to studies of site-related physiological responses to the local environment.

[Comparative analysis of postoperative complications on elderly colorectal cancer patients over 65 years with and without comorbid cardiovascular diseases].

OBJECTIVE: To investigate the risk of postoperative complications in elderly colorectal cancer patients over 65 years with comorbid cardiovascular diseases. METHODS: A total of 381 elderly colorectal cancer patients over 65 years were pathologically diagnosed as colorectal adenocarcinoma and underwent the first surgery in Beijing Hospital during January 2013 and December 2014. Patients were divided into comorbid cardiovascular disease group (258 cases) and non-cardiovascular disease group (123 cases) according to the existence of comorbid cardiovascular disease. The morbidity of postoperative complication was compared between two groups. RESULTS: There was no significant difference in the morbidity of postoperative complication between two groups [27.9%(72/258) vs. 29.3%(36/123), P>0.05]. According to the Clavien-Dindo classification of postoperative complications, the morbidities of complication at all levels between two groups were not significantly different(all P>0.05). But in terms of cardiovascular complications, the morbidity of comorbid cardiovascular disease group was significantly higher than that of non-cardiovascular disease group [7.4%(19/258) vs. 0.8%(1/123), χ2=6.678, P=0.010], while no significant differences in pulmonary and abdominal complications were found between two groups(all P>0.05). The morbidities of other complications (deep vein thrombosis, urinary tract infection and renal complications, etc.) of comorbid cardiovascular disease group were lower than those in non-cardiovascular disease group [2.7%(7/258) vs. 8.1%(10/123), χ2=5.733, P=0.017]. Different types of cardiovascular diseases, different levels of cardiac risk index and American Society of Anesthesiologists(ASA) rating were not significantly related to the patient's occurrence of postoperative complications(all P>0.05). CONCLUSIONS: Surgery treatment for elderly colorectal cancer patients over 65 years with comorbid cardiovascular diseases is safe. However, strict cardiovascular monitoring should be performed and necessary measures should be carried out in time.

Elevation-dependent variations of tree growth and intrinsic water-use efficiency in Schrenk spruce (Picea schrenkiana) in the western Tianshan Mountains, China.

Rising atmospheric CO2 concentration (C a) is expected to accelerate tree growth by enhancing photosynthesis and increasing intrinsic water-use efficiency (iWUE). However, the extent of this effect on long-term iWUE and its interactions with climate remains unclear in trees along an elevation gradient. Therefore, we investigated the variation in the radial growth and iWUE of mature Picea schrenkiana trees located in the upper tree-line (A1: 2700 m a.s.l.), middle elevation (A2: 2400 m a.s.l.), and lower forest limit (A3: 2200 m a.s.l.), in relation to the rising C a and changing climate in the Wusun Mountains of northwestern China, based on the basal area increment (BAI) and tree-ring δ(13)C chronologies from 1960 to 2010. We used the CRU TS3.22 dataset to analyze the general response of tree growth to interannual variability of regional climate, and found that BAI and δ(13)C are less sensitive to climate at A1 than at A2 and A3. The temporal trends of iWUE were calculated under three theoretical scenarios, as a baseline for interpreting the observed gas exchange at increasing C a. We found that iWUE increased by 12-32% from A1 to A3 over the last 50 years, and showed an elevation-dependent variation in physiological response. The significant negative relationship between BAI and iWUE at A2 and A3 showed that tree growth has been decreasing despite long-term increases in iWUE. However, BAI remained largely stable throughout the study period despite the strongest iWUE increase [at constant intercellular CO2 concentration (C i) before 1980] at A1. Our results indicate a drought-induced limitation of tree growth response to rising CO2 at lower elevations, and no apparent change in tree growth and diminished iWUE improvement since 1980 in the upper tree-line. This study may contradict the expectation that combined effects of elevated C a and rising temperatures have increased forest productivity, especially in high-elevation forests.

Pooled versus separate tree-ring δD measurements, and implications for reconstruction of the Arctic Oscillation in northwestern China.

Stable hydrogen isotope ratios (δD) in tree rings are an attractive but still rarely explored terrestrial archive of past climatic information. Because the preparation of the cellulose nitrate for δD measurements requires more wood and a longer preparation time than preparation techniques for other isotopes in cellulose (δ18O or δ13C), it is challenging to obtain high-resolution records, especially for slow-growing trees at high elevations and in boreal regions. Here, we tested whether annually pooled samples of Qinghai spruce (Picea crassifolia Kom.) trees from northwestern China provided results similar to those derived as the mean of individual measurements of the same trees and whether the resulting chronologies recorded useful climate information. Inter-tree variability of δD was higher than that of measured ring width for the same trees. We found higher and significant coherence between pooled and mean isotope chronologies than that among the individual series. It showed a logarithmic relationship between ring mass and δD; however, accounting for the influence of ring mass on δD values only slightly improved the strength of climatic signals in the pooled records. Tree-ring δD was significantly positively correlated with the mean, maximum, and minimum temperatures during the previous winter and with maximum temperature during the current August, and significantly negatively correlated with precipitation in the previous November to January and the current July. The winter climate signal seems to dominate tree-ring δD through the influence of large-scale atmospheric circulation patterns, i.e. the Arctic Oscillation. These results will facilitate reconstruction of winter atmospheric circulation patterns over northwestern China based on a regional tree-ring δD networks.

Tree growth and intrinsic water-use efficiency of inland riparian forests in northwestern China: evaluation via δ13C and δ18O analysis of tree rings.

The rising atmospheric CO2 concentration (Ca) has increased tree growth and intrinsic water-use efficiency (iWUE). However, the magnitude of this effect on long-term iWUE and whether this increase could stimulate the growth of riparian forests in extremely arid regions remain poorly understood. We investigated the relationship between growth [ring width; basal area increment (BAI)] and iWUE in a riparian Populus euphratica Oliv. forest to test whether growth was enhanced by increasing CO2 and whether this compensated for environmental stresses in the lower reaches of the inland Heihe River, northwestern China. We accomplished this using dendrochronological methods and carbon (δ(13)C) and oxygen (δ(18)O) isotopic analysis. We found an increase in BAI before 1958, followed by a decrease from 1958 to 1977 and an increase to a peak around 2000. Tree-ring carbon discrimination (Δ) and δ(18)O indicated significant negative overall trends from 1920 to 2012. However, the relationship shifted in strength and direction around 1977 from significantly negative to a weak connection. The seasonal minimum temperature in April to July showed strong influence on Δ, and δ(18)O was controlled by relative humidity (negatively correlated) and temperature (positively correlated) in June and July. The patterns of internal to atmospheric CO2 (Ci/Ca) suggest a specific adaptation of tree physiology to increasing CO2. Intrinsic water-use efficiency increased significantly (by 36.4%) during the study period. The increased iWUE explained 19.8 and 39.1% of the observed yearly and high-frequency (first-order difference) variations in BAI, respectively, after 1977. Our results suggest significant CO2 stimulation of riparian tree growth, which compensated for the negative influences of reductions in river streamflow and a drying climate during the study period.

[Laparoscopic with extralevator abdominoperineal excision for low rectal carcinoma].

OBJECTIVE: To explore the feasibility of laparoscopic with extralevator abdominoperineal excision (LELAPE group) for low rectal cancer. METHODS: From June 2011 to January 2013, 35 patients with low rectal cancer undergoing laparoscopic abdominoperineal excision at the Department of Gastroenterological Surgery, Beijing Hospital were analyzed retrospectively. Among them, 20 received laparoscopic abdominoperineal excision (LAPE group). There were 12 males and 8 females with an average age of (63 ± 6) years old. Another 15 patients underwent laparoscopic extralevator abdominoperineal excision (LELAPE group). There were 10 males and 5 females with an average age of (61 ± 7) years old. Operative duration, blood loss volume, time of postoperative out-of-bed activity, recovery of gastrointestinal function, removal time of drainage tube, edge of perineal position take out stitches time, postoperative hospital stay and complication rates were relative analyzed. RESULTS: There was no significant difference in operative time, time of postoperative out-of-bed activity, recovery of gastrointestinal function, removal time of perineal stitches, postoperative hospital stay and complication rates between 2 groups ((259 ± 52) vs (246 ± 55) min, (35 ± 13) vs (33 ± 9) d,(61 ± 25) vs (63 ± 20) h, (15.7 ± 2.5 ) vs (16.8 ± 2.9) d, (12 ± 3) vs (15 ± 4) d, 2/15 vs 3/20, all P > 0.05). Blood loss volume of perineal position in LELAPE group was less than those in LAPE group ((76 ± 31) vs (148 ± 36) ml, P < 0.05). Removal of perineal drainage tube in LELAPE group was earlier than that in LAPE group ((6.2 ± 1.6) vs (10.3 ± 1.8) d, P < 0.05). CONCLUSION: LELAPE is a safe and feasible surgical approach for low rectal cancer.