Nucleation of Stick-Slip Instability Within a Large-Scale Experimental Fault: Effects of Stress Heterogeneities Due to Loading and Gouge Layer Compaction

Geodetic observations and large-scale laboratory experiments show that seismic instability is preceded by slow slip within a finite nucleation zone. In laboratory experiments rupture nucleation is studied mostly using bare (rock) interfaces, whereas upper crustal faults are typically filled with gouge. To investigate effects of gouge on rupture nucleation, we performed a biaxial shearing experiment on a 350 mm long saw-cut fault filled with gypsum gouge, at room temperature and a minimum horizontal stress σ 2 = 0.3-5 MPa. The gouge layer was sandwiched between polymethylmethacrylate (PMMA) plates For reference also a fault without gouge was deformed. Strain gauges and Digital Image Correlation were used to monitor the deformation field along the fault zone margins. Stick-slip behavior occurred on both the gouge-filled fault and the PMMA fault. Nucleation of instability on the PMMA fault persistently occurred from one location 2/3 to 3/4 along the fault adjacent to a slow slip zone at the fault end, but nucleation on the gouge-filled fault was more variable, nucleating at the ends and/or at approximately 2/3 along the fault, with precursory slip occurring over a large fraction of the fault. Nucleation correlated to regions of high average fault stress ratio τ/σ n , which was more variable for the gouge-filled fault due to small length scale variations in normal stress caused by heterogeneous gouge compaction. Rupture velocities and slip rates were lower for the gouge-filled fault than for the bare PMMA fault. Stick-slip persisted when σ 2 was lowered and the nucleation zone length increased, expanding from the center to the sample ends before transitioning into instability.

Pathological changes from the originating to the peripheral sites of Sinonasal Inverted Papilloma are the underlying mechanisms of preoperative MRI-tumor origin prediction

BACKGROUND

Our previous study showed that convoluted cerebriform pattern (CCP)-based reverse tracing method in preoperative magnetic resonance imaging (MRI) is a reliable tool in predicting originating site of sinonasal inverted papilloma (SNIP). This study aimed to determine the underlying pathological mechanism of the preoperative MRI-CCP reverse tracing method by assessing the histopathological changes from the origin to the peripheral sites of SNIP.

METHODOLOGY

The originating site of SNIP was predicted by preoperative MRI in 30 consecutive patients suspected to have primary SNIP. Samples of SNIP originating and peripheral sites were processed by pathological staining for evaluation of stroma score, micro-vessel density (MVD), and tight junction proteins (claudin-5, zonula occludens (ZO)-1 and occludin) expression.

RESULTS

The originating site of SNIP was accurately predicted by preoperative MRI in all patients. Stroma scores, and MVD were significantly greater in the periphery of SNIP than in the originating site. In contrast, Claudin-5 expression in micro-vessels was greater at the originating site than the periphery.

CONCLUSIONS

More edematous stroma and intensive micro-vessels with defective tight junction in periphery of SNIP result in more contrast agent diffusing and CCP that can only be observed at the periphery of SNIP on T2 and contrast-enhanced T1 weighted MR images, which may be the mechanisms underlying the CCP reverse tracing method.

[The clinical value of totally laparoscopic stomach-partitioning gastrojejunostomy for malignant gastric outlet obstruction]

Objective: To explore the clinical value of totally laparoscopic stomach-partitioning gastrojejunostomy (TLSPGJ) for malignant gastric outlet obstruction. Methods: The clinical data of 9 gastric cancer patients who underwent TLSPGJ in Department of Pancreatic and Gastric Surgery, Cancer Hospital between September 2018 and September 2019 were retrospectively analyzed. Results: The mean operative blood loss of 9 cases were (13.3±5.0) ml, and the average operative time was (103.3±10.6) min. All patients received clear flow food on the first day after surgery. Postoperative first exhaust time was (3.1±0.8) days and the average postoperative hospital stay was (5.4±1.1) days. All of the 9 patients could tolerate semi-liquid food at discharge, and no postoperative complications such as bleeding or delayed gastric emptying occurred. Conclusion: TLSPGJ is an effective treatment for gastric output tract obstruction caused by malignant tumor.

[Comparison of short-term clinical outcome between laparoscopic distal pancreatectomy and open distal pancreatectomy]

Objective: To compare the short-term clinical effect between laparoscopic distal pancreatectomy (LDP) and open distal pancreatectomy (ODP). Methods: We performed a retrospective study on 161 patients who underwent pancreatectomy between September 2017 to December 2018 in the Department of Pancreatic and Gastric Surgery, Cancer Hospital of Chinese Academy of Medical Sciences. According to the mode of operation, the patients were divided into the LDP group (n=43) and the ODP group (n=118). To compare the short-term clinical effect and safety between the LDP group and the ODP group, the preoperative clinical data, intraoperative related index, postoperative complication, postoperative recovery index, preoperative and postoperative inflammatory index were analyzed. Results: The preoperative clinical characteristics between the LDP group and the ODP group were not statistically different (P>0.05). The intraoperative blood loss in LDP group was (194.19±241.83) ml, significantly less than (315.17±295.94) ml in ODP group (P<0.05), and the postoperative exhaust time in LDP group was (3.00±0.72) days, significantly shorter than (4.05±0.97) days in OPD group (P<0.001). The time to get out of bed in LDP group was (3.14±1.01) days, significantly shorter than (3.55±1.05) days in OPD group (P<0.05). The postoperative eating time in LDP group was (3.88±1.61) days, significantly shorter than (5.11±1.56) days in ODP group (P<0.001). The time of the drainage tube removal in LDP group was (8.44±1.93) days, significantly shorter than (9.82±3.70) days in ODP group (P<0.05). The postoperative hospital stay in LDP group was (9.65±3.57) days, significantly shorter than (11.99±6.57) days in ODP group (P<0.05). The mean operation time in LDP group was (168.65±55.45) min, shorter than (171.23±65.61) min in ODP group, but without significant difference (P>0.05). The incidences of non-pancreatic fistula-related complications in LDP group and ODP group were 16.3% and 11.0%, respectively, without statistical significance (P>0.05). The incidences of pancreatic fistula in LDP group and ODP group were 16.3% and 19.5%, respectively, without statistical significance (P>0.05). The total incidences of complications in LDP group and ODP group were 32.6% and 30.5%, respectively, without statistical significance (P>0.05). The preoperative and postoperative inflammatory indexes between these two groups were not statistically different (P>0.05). Conclusions: Compared with ODP, LDP has the advantages of less intraoperative blood loss, faster postoperative recovery, shorter postoperative hospital stays, without increased postoperative complications and prolonged operation time. LDP is a safe and feasible operation method, and its short-term clinical effect is better than that of ODP.

[Factors associated with sleep quality during first and second trimester in Chinese pregnant woman]

Objective: To investigate sleep quality in pregnant women during their first and second trimester and to identify risk factors. Methods: Data was from the Chinese Pregnant Women Cohort Study. A total of 3 618 pregnant women were included, with the exclusion 346 women who had missing information. Sociodemographic, health-related behavior, depression and sleep quality information were collected and analyzed. Logistic regression analysis were used to explore the influencing factors of sleep quality in pregnant women. Results: Among the 3 618 pregnant woman 28.2% had poor sleep quality in their first trimester and 28.7% in the second trimester. 15.2% pregnant women had progressively worse sleep and 13.0% had persistently poor sleep had pregnant women were generally suffered from poor sleep quality, difficulty falling asleep, sleep disorders and daily fatigue. Regular diet (OR=0.75, 95%CI: 0.62-0.92) and work (OR=0.84,95%CI: 0.71-0.99) in the first trimester were protective factors of sleep quality in pregnant women. Age ≥30 year old (OR=1.19, 95%CI: 1.03-1.37), passive smoking (OR=1.18, 95%CI: 1.02-1.36) and depression (OR=2.25, 95%CI: 1.95-2.61) in the first trimester were risk factors. Conclusions: The rate of poor sleep quality are high among Chinese pregnant woman during their first and second trimester. The risk factors of sleep quality are multiple. Regular diet and work, reduction of tobacco exposure, alleviation of depression symptom may help improve sleep quality among pregnant women.

Genome-wide CRISPR screening reveals genes essential for cell viability and resistance to abiotic and biotic stresses in Bombyx mori

High-throughput genetic screens are powerful methods to interrogate gene function on a genome-wide scale and identify genes responsible to certain stresses. Here, we developed a piggyBac strategy to deliver pooled sgRNA libraries stably into cell lines. We used this strategy to conduct a screen based on genome-wide clustered regularly interspaced short palindromic repeat technology (CRISPR)-Cas9 in Bombyx mori cells. We first constructed a single guide RNA (sgRNA) library containing 94,000 sgRNAs, which targeted 16,571 protein-coding genes. We then generated knockout collections in BmE cells using the piggyBac transposon. We identified 1006 genes that are essential for cell viability under normal growth conditions. Of the identified genes, 82.4% (829 genes) were homologous to essential genes in seven animal species. We also identified 838 genes whose loss facilitated cell growth. Next, we performed context-specific positive screens for resistance to biotic or nonbiotic stresses using temperature and baculovirus separately, which identified several key genes and pathways from each screen. Collectively, our results provide a novel and versatile platform for functional annotations of B. mori genomes and deciphering key genes responsible for various conditions. This study also shows the effectiveness, practicality, and convenience of genome-wide CRISPR screens in nonmodel organisms.

Comparative analysis of genome editing systems, Cas9 and BE3, in silkworms

The clustered regularly interspaced short palindromic repeats (CRISPR) system and the Cas9-derived proteins have been applied to genome editing in various organisms. Traditional Cas9 is typically used to knockout genes or specific DNA fragments based on the generation of double-stranded breaks, whereas nCas9 and dCas9 are fused with effectors to perform base pair transitions or epigenetic modification and regulation. However, this system has off-target effects and can cause genomic structure variations. Here, we comparatively analyzed Cas9 and BE3, an initial base editor based on the nCas9 fusion protein, in silkworms. Our results showed that base editing was superior to Cas9 in silkworm cultured cells. BE3 introduced accurate termination codons, whereas Cas9 did not. Moreover, Cas9 induced chromosome translocation, chromosome fragment repetition, and chromosome fragment deletion, with the deletion frequency reaching up to 4.29%. BE3 was not able to induce these changes in our study. Furthermore, Cas9-derived proteins blocked ribosome advance and mRNA transcription for 9 days, with a 9.40% repression effect by combining with double-stranded DNA when single guide RNAs were targeted in the coding region in silkworms. Overall, our findings established a strategy for choosing suitable editing tools for various applications in different organisms.

Investigation on saturable absorbers based on nonlinear Kerr beam cleanup effect

We experimentally investigate characteristics of saturable absorbers (SAs) based on nonlinear Kerr beam cleanup effect (NL-KBC). The SAs are formed by a long graded-index multimode fiber (GRIN MMF) with a short single-mode fiber served as a diaphragm. We studied the evolution of output spectrum and beam profiles from the GRIN MMF in order to investigate the mechanism of these SAs. We further performed saturable absorption measurements to evaluate their modulation depths and saturation intensities. We experimentally observed and first theoretically analyzed the "relaxation oscillation" behavior of the optical transmittance with increasing input intensity. We also studied their nonlinear polarization dynamics and observed the repolarized effect in NL-KBC regime. Our results confirm the optical properties of the SAs based on NL-KBC, and these SAs can find applications in Q-switched and mode-locked lasers.

MRI combined with PSA density in detecting clinically significant prostate cancer in patients with PSA serum levels of 4∼10ng/mL: Biparametric versus multiparametric MRI

PURPOSE

To compare the performance of biparametric magnetic resonance imaging (bpMRI) to that of multiparametric MRI (mpMRI) in combination with prostate-specific antigen density (PSAD) in detecting clinically significant prostate cancer (csPCa) in patients with PSA serum levels of 4∼10ng/mL.

MATERIALS AND METHODS

A total of 123 men (mean age, 66.3±8.9 [SD]; range: 42-83 years) with PSA serum levels of 4∼10ng/mL with suspected csPCa were included. All patients underwent mpMRI at 3 Tesla and transrectal ultrasound-guided prostate biopsy in their clinical workup and were followed-up for >1 year when no csPCa was found at initial biopsy. The mpMRI images were reinterpreted according to the Prostate Imaging Reporting and Data System (PI-RADS, v2.1) twice in two different sessions using either mpMRI sequences or bpMRI sequences. The patients were divided into 2 groups according to whether csPCa was detected. The PI-RADS (mpMRI or bpMRI) categories and PSAD were used in combination to detect csPCa. Receiver operating characteristic (ROC) curve and decision curve analyses were performed to compare the efficacy of the different models (mpMRI, bpMRI, PSAD, mpMRI+PSAD and bpMRI+PSAD).

RESULTS

Thirty-seven patients (30.1%, 37/123) had csPCa. ROC analysis showed that bpMRI (AUC=0.884 [95% confidence interval (CI): 0.814-0.935]) outperformed mpMRI (AUC=0.867 [95% CI: 0.794-0.921]) (P=0.035) and that bpMRI and mpMRI performed better than PSAD (0.682 [95% CI: 0.592-0.763]) in detecting csPCa; bpMRI+PSAD (AUC=0.907 [95% CI: 0.841-0.952]) performed similarly to mpMRI+PSAD (AUC=0.896 [95% CI: 0.828-0.944]) (P=0.151) and bpMRI (P=0.224). The sensitivity and specificity were 81.1% (95% CI: 64.8-92.0%) and 88.4% (95% CI: 79.7-94.3%), respectively for bpMRI, and 83.8% (95% CI: 68.0-93.8%) and 80.2% (95% CI: 70.2-88.0%), respectively for mpMRI (P>0.999 for sensitivity and P=0.016 for specificity). Among the 5 decision models, the decision curve analysis showed that all models (except for PSAD) achieved a high net benefit.

CONCLUSION

In patients with PSA serum levels of 4∼10ng/mL, bpMRI and bpMRI combined with PSAD achieve better performance than mpMRI in detecting csPCa; bpMRI has a higher specificity than mpMRI, which could decrease unnecessary biopsy, and may serve as a potential alternative to mpMRI to optimize clinical workup.

Let-7 microRNA is a critical regulator in controlling the growth and function of silk gland in the silkworm

The silk gland is characterized by high protein synthesis. However, the molecular mechanisms controlling silk gland growth and silk protein synthesis remain undetermined. Here we demonstrated that CRISPR/Cas9-based knockdown of let-7 or the whole cluster promoted endoreduplication and enlargement of the silk gland, accompanied by changing silk yield, whereas transgenic overexpression of let-7 led to atrophy and degeneration of the silk gland. Mechanistically, let-7 controls cell growth in the silk gland through coordinating nutrient metabolism processes and energy signalling pathways. Transgenic overexpression of pyruvate carboxylase, a novel target of let-7, resulted in enlargement of the silk glands, which is consistent with the abnormal phenotype of the let-7 knockdown. Overall, our data reveal a previously unknown miRNA-mediated regulation of silk gland growth and physiology and shed light on involvement of let-7 as a critical stabilizer and booster in carbohydrate metabolism, which may have important implications for understanding of the molecular mechanism and physiological function of specialized organs in other species.

[Progress and controversy of indocyanine green (ICG) used in laparoscopic navigation surgery for advanced gastric cancer]

Indocyanine green (ICG) has been used as a novel tracer for mapping lymph nodes in navigation surgeries for many malignant tumors. Recently, ICG is mainly applied in sentinel lymph node biopsy for early gastric cancer, while its application in advanced gastric cancer is less reported. It was reported that application of ICG in locating perigastric lymph nodes could elevate the efficiency of lymphadenectomy for advanced gastric cancer. Besides, recognizing small lymph nodes and dissecting certain lymph node stations are its unique advantages. However, some problems remain unsolved, as few relevant research has been done. Based on conceptions of minimal invasive and precision medicine, ICG may play an important role in improving the accuracy of laparoscopic surgery for advanced gastric cancer in the future.

Responses of hemocyanin and energy metabolism to acute nitrite stress in juveniles of the shrimp Litopenaeus vannamei

Nitrite is a common toxic substance in culture systems of Litopenaeus vannamei, and the stress may disturb hemocyanin synthesis and energy metabolism and result in shrimp death. In the present study, nitrite at concentrations of 0 (control), 3.3 (46.2 NO₂-N mg/L), 6.6 (92.4) and 9.9 mM (138.6) was used to evaluate the responses of hemocyanin level and energy metabolism in L. vannamei (5.80 ± 0.44 cm, 1.88 ± 0.38 g) for 96 h. The mortality rate at 96 h increased with nitrite concentration (50% at 9.9 mM, 40% at 6.6 mM, 30% at 3.3 mM, and 10% at 0 mM). In general, HIF-1α and hemocyanin mRNA expression in the nitrite stress groups was upregulated from 6 to 12 h and downregulated from 24 to 96 h. In the hemolymph, nitrite levels were significantly elevated in a dose-dependent manner, and exposure to nitrite stress significantly decreased the oxyhemocyanin content from 24 to 96 h. The glucose and lactate levels in the hemolymph in the nitrite stress groups were higher than those in the control group from 12 to 96 h. Compared with the control group, the shrimp in the nitrite stress groups exhibited decreased glycogen concentrations in the hepatopancreas. The triglyceride (TG) levels in the nitrite stress groups were all higher than those in the control group from 48 to 96 h. The hexokinase (HK) activity in the hepatopancreas and muscle increased in the nitrite stress groups from 48 to 96 h. In general, nitrite stress enhanced the activities of pyruvate kinase (PK), phosphofructokinase (PFK) and lactate dehydrogenase (LDH) in muscle from 24 to 96 h. In addition, nitrite stress decreased the activities of succinate dehydrogenase (SDH) and fatty acid synthase (FAS) from 24 to 96 h in the hepatopancreas and muscle. This study indicates that exposure to nitrite stress can enhance the accumulation of nitrite in the hemolymph and then reduce oxygenation and hemocyanin synthesis, leading to tissue hypoxia and thereby resulting in accelerated anaerobic metabolism and the inhibition of aerobic metabolism. The effects of nitrite stress on hemocyanin synthesis and energy metabolism may be one of the reasons for the mortality of L. vannamei in culture systems.

[Risk factors for preterm birth, low birth weight and small for gestational age: a prospective cohort study]

Objective: To study the relationship between exposure factors in early pregnancy and preterm birth (PB), low birth weight (LBW) and small for gestational age (SGA) of neonates. Methods: A total of 3 172 pregnant women who were enrolled in the project of Chinese Pregnant Women Cohort Study-Peking Union Medical College (CPWCS-PUMC) from July 25, 2017 to July 24, 2018 and delivered before December 31, 2018 were selected as subjects in this study. The relationship between exposure factors in early pregnancy and adverse outcomes of neonatal delivery was analyzed by using binary logistic regression analysis. Results: The incidence rates of PB, LBW and SGA were 4.76%, 3.53% and 5.74%, respectively. In terms of PB, the analysis results showed that the gestational weight gain (GWG) and living in northern China were protective factors, while premature rupture of membranes, gestational hypertension, dental examination or treatment within 1-3 years and family with 3-4 members were risk factors. In the respect of LBW, GWG and daily consumption of milk and dairy products were the protective factors, while premature rupture of membranes, gestational hypertension, sedentary working time more than 6 hours, dental examination or treatment within 1-3 years and passive smoking were risk factors. For SGA, baby girl, passive smoking, peanut oil consumption and unsalted taste were risk factors, while folic acid supplementation was protective factor. Conclusion: The risk factors for PB, LBW and SGA were multifactorial, and relevant specific measures should be taken to reduce the occurrence of adverse neonatal outcomes.

Limited effects of the comprehensive pricing healthcare reform in China

OBJECTIVES

To evaluate the effects of China's very recent comprehensive pricing healthcare reform, taking the patients' perspective.

STUDY DESIGN

Two survey studies were conducted using the same protocol in Beijing in July 2017 and 2018, respectively.

METHODS

The same questionnaire was used and contains two sections, with the first on demographic and personal information and the second on various assessments of the reform.

RESULTS

Findings different from those in the government-led evaluations were made. Specifically, the majority of the patients thought the level of medical service fee and cost of medicine still high, and experienced no change or an increase in overall medical cost. The overall assessment of the reform was not sufficiently positive. Multiple problems in healthcare were identified. Development from 2017 to 2018 was not significantly positive.

CONCLUSIONS

Patients' assessments of the reform were not as positive as those made in the government-led evaluations. In extending the reform to the whole country, the government and healthcare providers may need to further tune the reform to better serve the public.