Human amniotic mesenchymal stem cell-islet organoids enhance the efficiency of islet engraftment in a mouse diabetes model.

AIMS: Despite islet transplantation has proved a great potential to become the standard therapy for type 1 diabetes mellitus (T1DM), this approach remains limited by ischemia, hypoxia, and poor revascularization in early post-transplant period as well as inflammation and life-long host immune rejection. Here, we investigate the potential and mechanism of human amniotic mesenchymal stem cells (hAMSCs)-islet organoid to improve the efficiency of islet engraftment in immunocompetent T1DM mice. MAIN METHODS: We generated the hAMSC-islet organoid structure through culturing the mixture of hAMSCs and islets on 3-dimensional-agarose microwells. Flow cytometry, whole-body fluorescent imaging, immunofluorescence, Calcein-AM/PI staining, ELISA, and qPCR were used to assess the potential and mechanism of shielding hAMSCs to improve the efficiency of islet transplantation. KEY FINDINGS: Transplant of hAMSC-islet organoids results in remarkably better glycemic control, an enhanced glucose tolerance, and a higher ß cell mass in vivo compared with control islets. Our results show that hAMSCs shielding provides an immune privileged microenvironment for islets and promotes graft revascularization in vivo. In addition, hAMSC-islet organoids show higher viability and reduced dysfunction after exposure to hypoxia and inflammatory cytokines in vitro. Finally, our results show that shielding with hAMSCs leads to the activation of PKA-CREB-IRS2-PI3K and PKA-PDX1 signaling pathways, up-regulation of SIL1 mRNA levels, and down-regulation of MT1 mRNA levels in ß cells, which ultimately promotes the synthesis, folding and secretion of insulin, respectively. SIGNIFICANCE: hAMSC-islet organoids can evidently increase the efficiency of islet engraftment and might develop into a promising alternative for the clinical treatment of T1DM.

Enhancing Oral Performance of Paclitaxel Lipid-Mimic Prodrug via Modulating Type of Fatty Acids.

Owing to the serious clinical side effects of intravenous Taxol, an oral chemotherapeutic strategy is expected to be promising for paclitaxel (PTX) delivery. However, its poor solubility and permeability, high first-pass metabolism, and gastrointestinal toxicity need to be overcome. A triglyceride (TG)-like prodrug strategy facilitates oral drug delivery by bypassing liver metabolism. However, the effect of fatty acids (FAs) in sn-1,3 on the oral absorption of prodrugs remains unclear. Herein, a series of TG-mimetic prodrugs of PTX is explored with different carbon chain lengths and degrees of unsaturation of FAs at the sn-1,3 position in an attempt to enhance oral antitumor effect and to guide the design of TG-like prodrugs. Interestingly, the different FA lengths exhibit great influence on in vitro intestinal digestion behavior, lymph transport efficiency, and up to fourfold differences in plasma pharmacokinetics. The prodrug with long-chain FAs shows a more effective antitumor effect, whereas the degree of unsaturation has a negligible impact. The findings illustrate how FAs structures affect the oral delivery efficiency of TG-like PTX prodrugs and thus provide a theoretical basis for their rational design.

[Advances of the Regulation of microRNAs in Follicular Development].

In recent years,microRNAs(miRNAs)have been detected at different stages of follicular development and in different cells of follicles.Extracellular vesicle(EV)-derived miRNAs have also been detected in the follicular fluid of mature follicles.miRNAs participate in the regulation of normal follicular development,and the regulation disorder may lead to the occurrence of some ovarian diseases.In order to further systematically elucidate the regulatory mechanism of miRNAs on follicular development and find suitable EV-derived miRNAs that can predict oocyte development,we reviewed the functions of miRNAs in follicular development from the perspectives of granulosa cell development,oocyte development,and hormone synthesis.

Octreotide treatment of cancer chemoradiotherapy-induced diarrhoea: a meta-analysis of randomized controlled trials.

BACKGROUND: Patients receiving radiotherapy and chemotherapy have a high risk developing to an acute chemoradiotherapy-induced diarrhea (RID). The clinical efficacy of octreotide in controlling chemoradiotherapy-induced diarrhea remains controversial. We performed a meta-analysis of randomized controlled trials (RCTs) to evaluate the efficacy of octreotide for treatment the chemoradiotherapy-induced diarrhoea. METHODS: Relevant RCTs studies assessing the effect of octreotide on clinical outcomes compared with placebo were searched in Cochrane Library, PubMed, EMBASE and Web of Science (up to December 2018). Heterogeneity was assessed with I2, and publication bias was evaluated using sensitive analysis. RESULTS: Eight trials, a total of 594 participants. We found octreotide was significantly effective compared with the control group (OR =3.17; 95% CI, 1.28-7.85; P<0.0001). The overall effect of octreotide was 62.5% (220/352), while that of the control group was 49.3% (168/341). We found octreotide group was effective compared with the control group in 24, 48, and 96 h (OR =16.02; 95% CI, 3.51-73.15; P=0.0003), (OR =4.70; 95% CI, 1.65-13.42; P=0.004) and (OR =14.49; 95% CI, 6.24-33.65; P<0.00001). CONCLUSIONS: Octreotide is superior to conventional therapy in the duration and effectiveness for chemoradiotherapy-induced diarrhea.

Interaction of polymorphisms in xeroderma pigmentosum group C with cigarette smoking and pancreatic cancer risk.

The aim of the present study was to evaluate the association between xeroderma pigmentosum group C (XPC) polymorphisms and pancreatic cancer (PC) risk. A total of 7 XPC tagging SNPs (tag-SNPs) were selected from the International HapMap Project Databases (rs2228001A/C, rs2470353G/C, rs2228000C/T, rs3731114C/G, rs3729587G/C, rs2607775C/G and rs3731055G/A) and were genotyped in 205 patients with PC and 230 non-cancer control subjects using a SNaPshot assay. The C allelic gene frequency of rs2470353 was higher in patients with PC compared with that in the control group (P=0.003). Compared with the GG gene type, PC risk was increased in subjects with GC and GC+CC gene types (P=0.012 and P=0.006, respectively). PC risk increased 3.505-fold for the subjects who were heavy smokers (tobacco, ≥25 packets/year) with the GC+CC gene type (P=0.008). The G allelic gene frequency of rs2607775 was higher in PC patients compared with that in the control group (P=0.003). Compared with the CC gene type, PC risk increased in subjects with CG and CG+GG gene types (P=0.013 and P=0.005, respectively). Furthermore, PC risk increased 3.950-fold in subjects who were heavy smokers (tobacco, ≥25 packets/year) with the CG+GG gene type (P=0.001). Haplotype analysis further revealed that the CCC haplotype of rs2228000, rs3731114 and rs3729587 increased PC risk (odds ratio, 1.610; 95% confidence interval, 1.035-2.481; P=0.034). The present study revealed that XPC gene polymorphisms could increase the risk of PC in the study population, particularly among heavy smokers.

Expression of Smo in pancreatic cancer CD44+CD24+cells and construction of a lentiviral expression vector to silence Smo.

The present study focused on the roles of members of the Hedgehog (Hh) signaling pathway in the maintenance of malignant biological characteristics, such as tumorigenesis, similar to that of pancreatic tumor cells. Cluster of differentiation (CD)44+CD24+/CD44-CD24- cells were isolated from three different pancreatic cancer cell lines by flow cytometry. Among the three pancreatic cancer cell lines, the SW1990 cell line exhibited the highest percentage of CD44+CD24+ cells, which accounted for 39.9% of the total. The expression of members of the Hh signaling pathway in CD44+CD24+/CD44-CD24- cells was detected using reverse transcription-polymerase chain reaction and western blot analysis. The results demonstrated that members of the Hh signaling pathway were differentially expressed in CD44+CD24+ cells compared with CD44-CD24-, normal pancreatic duct cells and unsorted SW1990 cells. In addition, lentiviral expression vectors expressing Smoothened (Smo) small interfering RNA (siRNA) were constructed. Following transfection with the lentiviral expression vectors, Smo expression was markedly reduced in CD44+CD24+ cells. The present study represents a preliminary investigation into the biological characteristics of CD44+CD24+ pancreatic cancer cells.

Significance and prognosis of epithelial-cadherin expression in invasive breast carcinoma.

The objective of the present study was to investigate and analyze the epithelial-cadherin (E-cadherin) expression in invasive ductal carcinoma of the breast, and to analyze the associations between the expression and clinicopathological characteristics of lymph node metastasis and the prognosis of breast cancer. The immunohistochemical streptavidin-peroxidase method was used to detect the E-cadherin expression in 30 cases of breast fibroadenoma and in 450 cases of invasive breast cancer, and then the χ2test and Kaplan-Meier method were used to analyze the data. The 30 cases of breast fibroadenoma showed positive expression of E-cadherin. Specifically, results found that E-cadherin was highly expressed in 49.04% (77/157) of patients with non-metastatic breast cancer, while low expression was found in 50.96% (80/157). Additionally, E-cadherin was highly expressed in 29.69% (87/293) of patients with lymph node metastasis of breast cancer, with low expression in 70.31% (206/293); these differences were significantly different (χ2=16.53; P<0.001). E-cadherin was expressed in 35.48% (22/62), 33.73% (84/249), 63.83% (30/47) and 30.43% (28/92) of patients with luminal A type, luminal B type, human epidermal growth factor receptor-2positive and triple-negative breast cancer (TNBC), respectively. It was found that patients with high expression of E-cadherin had a better prognosis than the low expression group with regards to TNBC, and this result was significantly different (χ2=4.48; P=0.034). In conclusion, low E-cadherin expression was associated with lymph node metastasis in invasive breast cancer, and the patients with low expression also had a poor prognosis compared with those in the high expression group. The present results suggested that E-cadherin could be used in a prognostic index for patients with lymph node metastasis and TNBC.

Effect of Huaier granule on recurrence after curative resection of HCC: a multicentre, randomised clinical trial.

OBJECTIVE: There is little evidence that adjuvant therapy after radical surgical resection of hepatocellular carcinoma (HCC) improves recurrence-free survival (RFS) or overall survival (OS). We conducted a multicentre, randomised, controlled, phase IV trial evaluating the benefit of an aqueous extract of Trametes robinophila Murr (Huaier granule) to address this unmet need. DESIGN AND RESULTS: A total of 1044 patients were randomised in 2:1 ratio to receive either Huaier or no further treatment (controls) for a maximum of 96 weeks. The primary endpoint was RFS. Secondary endpoints included OS and tumour extrahepatic recurrence rate (ERR). The Huaier (n=686) and control groups (n=316) had a mean RFS of 75.5 weeks and 68.5 weeks, respectively (HR 0.67; 95% CI 0.55 to 0.81). The difference in the RFS rate between Huaier and control groups was 62.39% and 49.05% (95% CI 6.74 to 19.94; p=0.0001); this led to an OS rate in the Huaier and control groups of 95.19% and 91.46%, respectively (95% CI 0.26 to 7.21; p=0.0207). The tumour ERR between Huaier and control groups was 8.60% and 13.61% (95% CI -12.59 to -2.50; p=0.0018), respectively. CONCLUSIONS: This is the first nationwide multicentre study, involving 39 centres and 1044 patients, to prove the effectiveness of Huaier granule as adjuvant therapy for HCC after curative liver resection. It demonstrated a significant prolongation of RFS and reduced extrahepatic recurrence in Huaier group. TRIAL REGISTRATION: NCT01770431; Post-results.

Contribution of DNA repair xeroderma pigmentosum group D genotypes to pancreatic cancer risk in the Chinese Han population

Abstract This study aimed to determine the association between the polymorphisms and haplotypes in the xeroderma pigmentosum group D (XPD) gene and the risk of pancreatic cancer in the Chinese Han population. SNaPshot was used for genotyping six SNP sites of the XPD gene. Comparisons of the correlations between different genotypes in combination with smoking and the susceptibility to pancreatic cancer were performed. Individual pancreatic cancer risk in patients who carry mutant C alleles (AC, CC, and AC+CC) at rs13181 increased (p < 0.05). Taking non-smoking individuals who carry the AA genotype as a reference, and non-smoking individuals who carry mutant allele C (AC+CC), the risk of pancreatic cancer increased by 3.343 times in individuals who smoked ≥ 20 cigarettes daily, 3.309 times in individuals who smoked ≥ 14 packs per year, 5.011 times in individuals who smoked ≥ 24 packs per year, and 4.013 times in the individuals who smoked ≥ 37 packs per year (P < 0.05). In addition, haplotype analysis revealed that haplotype AGG, which comprised rs13181, rs3916874 and rs238415, was associated with a 1.401-fold increase in pancreatic cancer risk (p < 0.05). We conclude that the polymorphism of XPD Lys751Gln (rs13181) in combination with smoking contributes to increased risk of pancreatic cancer in the Chinese Han population. Haplotype AGG might be a susceptibility haplotype for pancreatic cancer.

Contribution of DNA repair xeroderma pigmentosum group D genotypes to pancreatic cancer risk in the Chinese Han population.

This study aimed to determine the association between the polymorphisms and haplotypes in the xeroderma pigmentosum group D (XPD) gene and the risk of pancreatic cancer in the Chinese Han population. SNaPshot was used for genotyping six SNP sites of the XPD gene. Comparisons of the correlations between different genotypes in combination with smoking and the susceptibility to pancreatic cancer were performed. Individual pancreatic cancer risk in patients who carry mutant C alleles (AC, CC, and AC+CC) at rs13181 increased (p < 0.05). Taking non-smoking individuals who carry the AA genotype as a reference, and non-smoking individuals who carry mutant allele C (AC+CC), the risk of pancreatic cancer increased by 3.343 times in individuals who smoked ≥ 20 cigarettes daily, 3.309 times in individuals who smoked ≥ 14 packs per year, 5.011 times in individuals who smoked ≥ 24 packs per year, and 4.013 times in the individuals who smoked ≥ 37 packs per year (P < 0.05). In addition, haplotype analysis revealed that haplotype AGG, which comprised rs13181, rs3916874 and rs238415, was associated with a 1.401-fold increase in pancreatic cancer risk (p < 0.05). We conclude that the polymorphism of XPD Lys751Gln (rs13181) in combination with smoking contributes to increased risk of pancreatic cancer in the Chinese Han population. Haplotype AGG might be a susceptibility haplotype for pancreatic cancer.

HLA-A*02-B*46 haplotype: an adverse prognostic factor in Han patients with nasopharyngeal carcinoma.

Epidemiological studies have shown that human leukocyte antigen (HLA) allelic polymorphisms are closely correlated to susceptibility to nasopharyngeal carcinoma (NPC), and in a previous study, we showed that HLA-B*46 and HLA-A*02-B*46 haplotypes were strongly associated with NPC susceptibility. In this retrospective study, we investigated the phenotype of the HLA-A and HLA-B alleles and haplotypes and correlated these data to the clinical and pathological parameters of NPC to understand the role of HLA alleles and haplotypes in NPC prognosis. The cohort comprised 117 NPC patients from a Han population in Xinjiang. The local recurrence-free survival (LRFS), distant metastasis- free survival (DMFS), disease-free survival (DFS), and overall survival (OS) were analyzed. The 5-year DMFS of the HLA-A*02-B*46 haplotype carriers and non-carriers was 66.4% and 90.3%, respectively. In addition, age was found to be a prognostic factor for LRFS, DFS, and OS (P=0.032, 0.040, and 0.013, respectively). We found that the HLA-A*02-B*46 haplotype might be a prognostic marker in addition to the traditional TNM staging in patients with NPC.

[Regulatory Role of Nitric Oxide in Development and Hatching of Mouse Blastocysts].

OBJECTIVE: To determine the regulatory role and mechanism of nitric oxide (NO) in the development and hatching of mouse blastocysts. METHODS: The Kunming female mice were superovulated and then mated with mature male mice. On the day 2.5 of their pregnancy, morulae were flushed from their uterine horns with culture media. Morulae were cultured in different concentrations of N-nitro-L arginine methyl ester (L-NAME), sodium nitroprusside (SNP), or the combination of L-NAME and SNP in culture media for 48 hours. The development and hatching of blastocysts were examined on day 4 and day 5 and the total numbers of blastocyst cells and cysteinyl aspartate specific proteinase 3 (caspase 3) were observed under confocal laser scanning microscope. RESULTS: With the increase of the concentration of L-NAME or SNP, the hatching rate of blastocysts and the total number of blastocyst cells were significantly reduced. The addition of 10 nmol/L SNP in culture media with 5 mmol/L L-NAME significantly increased the development of blastocysts and promoted hatching of blastocysts. However, with increase of SNP concentration in culture media with 5 mmol/L L-NAME, the development and hatching rates of blastocysts were significantly decreased. L-NAME had no obvious effect on the expression of active caspase 3 in blastocyst cells. However,when being above 500 nmol/L,SNP significantly increased the expression of caspase 3 in blastocyst cells. CONCLUSIONS: NO plays an important role in development and hatching of mouse blastocysts. Excessively high or low NO can damage the division of blastomeres, resulting in the failure of the blastocyst development and hatching. Also, excessively high NO can lead to the apoptosis of the blastocyst cells.

Intrathecal injection of lentivirus-mediated glial cell line-derived neurotrophic factor RNA interference relieves bone cancer-induced pain in rats.

Bone cancer pain is a common symptom in cancer patients with bone metastases and the underlying mechanisms are largely unknown. The aim of this study is to explore the endogenous analgesic mechanisms to develop new therapeutic strategies for bone-cancer induced pain (BCIP) as a result of metastases. MRMT-1 tumor cells were injected into bilateral tibia of rats and X-rays showed that the area suffered from bone destruction, accompanied by an increase in osteoclast numbers. In addition, rats with bone cancer showed apparent mechanical and thermal hyperalgesia at day 28 after intratibial MRMT-1 inoculation. However, intrathecal injection of morphine or lentivirus-mediated glial cell line-derived neurotrophic factor RNAi (Lvs-siGDNF) significantly attenuated mechanical and thermal hyperalgesia, as shown by increases in paw withdrawal thresholds and tail-flick latencies, respectively. Furthermore, Lvs-siGDNF interference not only substantially downregulated GDNF protein levels, but also reduced substance P immunoreactivity and downregulated the ratio of pERK/ERK, where its activation is crucial for pain signaling, in the spinal dorsal horn of this model of bone-cancer induced pain. In this study, Lvs-siGDNF gene therapy appeared to be a beneficial method for the treatment of bone cancer pain. As the effect of Lvs-siGDNF to relieve pain was similar to morphine, but it is not a narcotic, the use of GDNF RNA interference may be considered as a new therapeutic strategy for the treatment of bone cancer pain in the future.

Knockdown of OCT4 suppresses the growth and invasion of pancreatic cancer cells through inhibition of the AKT pathway.

Octamer­binding transcription factor 4 (OCT4) is one of the factors associated with self­renewal and differentiation in cancer stem cells, and is crucial for the progression of various types of human malignancy. However, the expression and function of OCT4 in human pancreatic cancer has not been fully elucidated. The purpose of the present study was to investigate the function and molecular mechanisms of OCT4 in pancreatic cancer cells. The clinical significance of OCT4 expression was assessed by an immunohistochemical assay using a tissue microarray procedure in pancreatic cancer tissues and cells with different degrees of differentiation. A loss­of­function approach was used to examine the effects of a lentivirus­mediated OCT4 small hairpin RNA vector on biological behaviors, including cell proliferative activity and invasive potential. The results demonstrated that the expression levels of OCT4 protein in cancer tissues were significantly elevated compared with those in adjacent non­cancerous tissues (65.0 vs. 42.5%; P=0.005), which was correlated with tumor differentiation (P=0.008). The knockdown of OCT4 inhibited the proliferation and invasion of pancreatic cancer cells (Panc­1) expressing high levels of OCT4, accompanied with decreased expression of AKT, proliferating cell nuclear antigen (PCNA) and matrix metalloproteinase­2 (MMP­2). In conclusion, the present study reveals that the increased expression of OCT4 is correlated with the differentiation of pancreatic cancer, while knockdown of OCT4 suppresses the growth and invasion of pancreatic cancer cells through inhibition of AKT pathway­mediated PCNA and MMP­2 expression, suggesting that OCT4 might serve as a potential therapeutic target for the treatment of pancreatic cancer.

[Relationship between single nucleotide polymorphisms and its haplotype of X-ray repair cross complementing group 1 and susceptibility of pancreatic carcinoma].

OBJECTIVE: The aim of this study was to evaluate the effects of XRCCl gene polymorphisms and its haplotype on the susceptibility of pancreatic carcinoma. METHODS: Peripheral blood DNA was extracted from 210 pancreatic carcinoma patients and 213 control subjects. SNaPshot technique was used for genotyping seven SNP sites of the XRCCl gene (rs3213403, rs25487, rs1799782, rs731420, rs1001581, rs12611088, and rs3213282). Logistic regression model was performed to analyze the relationship of different genotypes or haplotype and the susceptibility of pancreatic carcinoma. RESULTS: The frequency for allele A at site rs25487 in the case group was significantly higher than that in the control group (P < 0.05). The frequency of GG, GA and AA genotype between the case group and control group had statistically significant differences (P < 0.05). Compared with GG genotype, the risk of pancreatic carcinoma in the subjects carrying mutated allele A (GA+AA) was increased by 0.648 times (P < 0.05). Among them the pancreatic carcinoma risk of individuals carrying A allele was increased by 0.552 times compared with the individuals carrying G allele. The frequency of allele and genotype at site rs1799782 in the case group and control group had a significant difference (P < 0.05). Compared with the CC genotype, the risk of pancreatic carcinoma in the subjects carrying mutated allele T (CT+TT) was increased by 0.683 times. Among them the pancreatic carcinoma risk of individuals carrying T allele was increased by 0.549 times compared with the individuals carrying C allele. Significant differences were observed in linkage disequilibrium between any two of the seven SNPs (P < 0.05), the frequency of H4-AGCCCGC, H6-GGCCCGG or H7-AGCCTAG haplotypes was significantly lower in the case group than that in the control group (P < 0.05). CONCLUSIONS: The single nucleotide polymorphisms of rs25487 and rs1799782 for XRCC1 gene may be correlated with the occurrence of pancreatic carcinoma. The haplotypes of H4-AGCCCGC, H6-GGCCCGG and H7-AGCCTAG might be a potential genetic protective factor for the occurrence of pancreatic carcinoma.

Influence of the adjuvant therapy on the survival of patients with stage II pancreatic carcinoma.

This study aimed to investigate the effect of adjuvant therapy on the treatment of stage II pancreatic carcinomas. The clinical data of 139 cases of stage II pancreatic carcinoma were analyzed retrospectively. The overall 1-, 3-, and 5-year cumulative survival rates of 139 patients were 40%, 6%, and 3%, respectively, and the median survival time (MST) was 279 days. The MST was 399 days for those with adjuvant therapy, 210 days for those without adjuvant therapy, 390 days for the radical resection group, 270 days for the bypass operation and laparotomy group, and 132 days for the nonsurgical group. The adjuvant therapy could not prolong the survival time and decrease the liver metastasis rate of the patients with stage II carcinoma significantly in radical resection group (P>0.05). In the bypass operation and laparotomy group and nonsurgical group, the adjuvant therapy could improve the survival of the patients significantly (P<0.05); however, the survival rate was not significantly different among systemic venous chemotherapy, radiation therapy, interventional therapy, and combination therapy (P>0.05); or between gemcitabine (GEM) regimen and 5-fluorouracil regimen (P>0.05); or between GEM monotherapy and GEM combined with platinum/capecitabine (P>0.05). The proper adjuvant therapy can be suggested according to the general condition of the patients after radical resection for stage II pancreatic carcinoma. Chemotherapy combined with radiation should be applied actively for the patients whose cancerous tissues were not radically resected. The clinical efficacy of GEM combined with platinum/capecitabine is relatively better than GEM.

[Effect of noninvasive positive pressure ventilation on treatment of acute respiratory distress syndrome].

OBJECTIVE: To investigate the factors affecting the effect of noninvasive positive pressure ventilation (NIPPV) on treatment of acute respiratory distress syndrome (ARDS). METHODS: According to the disease-induced factors, patients with ARDS were divided into two groups: group A (pulmonary factors), group B (extra-pulmonary factors). Different kinds of ventilator s were used in the course of NIPPV via facial or nasal mask. The mode, biphasic intermittent positive airway pressure (BiPAP, BiPAP vision), pressure support ventilation (PSV) + positive end-expiratory pressure (PEEP) or synchronized intermittent mandatory ventilation (SIMV) + PSV + PEEP, was administered. After 3-10 hours, the patients who were not fit to NIPPV were conducted intubation. RESULTS: Group A had 9 cases, of whom 5 cases were treated with NIPPV all the time, while in group B, 14 cases, of whom 12 cases The cure rate of group A by NIPPV was 55.6% (5/9), while that of group B was 85.7% (12/14), P<0.05. CONCLUSION: Selecting proper indication, reasonable ventilator mode and parameters, and improving the unfavorable factors can contribute to the decrease of intubation rate.