Pediatric tympanostomy tube assessment via deep learning.

PURPOSE: Tympanostomy tube (TT) placement is the most frequently performed ambulatory surgery in children under 15. After the procedure it is recommended that patients follow up regularly for "tube checks" until TT extrusion. Such visits incur direct and indirect costs to families in the form of days off from work, copays, and travel expenses. This pilot study aims to compare the efficacy of tympanic membrane (TM) evaluation by an artificial intelligence algorithm with that of clinical staff for determining presence or absence of a tympanostomy tube within the TM. METHODS: Using a digital otoscope, we performed a prospective study in children (ages 10 months-10 years) with a history of TTs who were being seen for follow up in a pediatric otolaryngology clinic. A smartphone otoscope was used by study personnel who were not physicians to take ear exam images, then through conventional otoscopic exam, ears were assessed by a clinician for tubes being in place or tubes having extruded from the TM. We trained and tested a deep learning (artificial intelligence) algorithm to assess the images and compared that with the clinician's assessment. RESULTS: A total of 123 images were obtained from 28 subjects. The algorithm classified images as TM with or without tube in place. Overall classification accuracy was 97.7 %. Recall and precision were 100 % and 96 %, respectively, for TM without a tube present, and 95 % and 100 %, respectively, for TM with a tube in place. DISCUSSION: This is a promising deep learning algorithm for classifying ear tube presence in the TM utilizing images obtained in awake children using an over-the-counter otoscope available to the lay population. We are continuing enrollment, with the goal of building an algorithm to assess tube patency and extrusion.

Comparison of contrast-enhanced ultrasonography and MRI results obtained by expert and novice radiologists indicating short-term response after transarterial chemoembolisation for hepatocellular carcinoma.

AIM: To evaluate inter-reader agreement between novice and expert radiologists in assessing contrast-enhanced ultrasonography (CEUS) and magnetic resonance imaging (MRI) images for detecting viable tumours with different sizes after conventional transarterial chemoembolisation (cTACE). MATERIALS AND METHODS: This prospective study included patients who had less than five hepatomas and who underwent cTACE. Hepatomas with one or two feeding arteries were selected as target lesions. CEUS and MRI were performed within 1 week after cTACE to evaluate viable tumours. RESULTS: The expert group had higher kappa values in evaluating all tumour sizes via CEUS compared with MRI. The novice group had similar kappa values. In patients with tumours measuring ≤3 cm, the expert group had higher kappa values in reading CEUS compared with MRI images; however, in the novice group, the kappa value was lower in evaluating CEUS compared with MRI images. In patients with tumours measuring >3 cm, the expert and novice groups had good to excellent kappa values. The confidence level of the two groups in reading MRI images was high; however, the novice group had a lower confidence level. CONCLUSION: CEUS is a convenient, cost-effective, and easy to apply imaging tool that can help interventionists perform early detection of viable hepatocellular carcinoma post-TACE. It has a higher inter-rater agreement in interpreting CEUS images compared with MRI images among expert radiologists even when they are extremely familiar with post-cTACE MRI images. In novice radiologists, there may be a learning curve to achieve good consistency in CEUS interpretation.

SAR user guide to the rectal MR synoptic report (primary staging).

Rectal MR is the key diagnostic exam at initial presentation for rectal cancer patients. It is the primary determinant in establishing clinical stage for the patient and greatly impacts the clinical decision-making process. Consequently, structured reporting for MR is critically important to ensure that all required information is provided to the clinical care team. The SAR initial staging reporting template has been constructed to address these important items, including locoregional extent and factors impacting the surgical approach and management of the patient. Potential outputs to each item are defined, requiring the radiologist to commit to a result. This provides essential information to the surgeon or oncologist to make specific treatment deisions for the patient. The SAR Initial Staging MR reporting template has now been officially adopted by the NAPRC (National Accreditation Program for Rectal Cancer) under the American College of Surgery. With the recent revisions to the reporting template, this user guide has been revamped to improve its practicality and support to the radiologist to complete the structured report. Each line item of the report is supplemented with clinical perspectives, images, and illustrations to help the radiologist understand the potential implications for a given finding. Common errors and pitfalls to avoid are highlighted. Ideally, rectal MR interpretation should not occur in a vacuum but in the context of a multi-disciplinary tumor board to ensure that healthcare providers use common terminology and share a solid understanding of the strengths and weaknesses of MR.

NLRP3 rs1539019 is significantly associated with chronic obstructive pulmonary disease in a Chinese Han population: a case-control study.

OBJECTIVE: COPD is a complex respiratory disease characterized by chronic airway inflammation and the airflow limitations are not fully reversible due to the combination of genetic and environmental factors. Genetic factors such as polymorphisms, may affect the susceptibility of COPD. In the present study, we examined the association between the polymorphisms of three genes and COPD risk in a Chinese Han population. PATIENTS AND METHODS: A total of 375 COPD patients and 284 control subjects were recruited from November 2018 to June 2021. Data on demographic basic information, smoking status, history of coal dust exposure, and peripheral blood were collected from subjects of two groups. Three polymorphisms (NLRP3 rs1539019, LAMB1 rs4320486,  IL-6 rs1800796) were analyzed. Logistic analysis was used to evaluate the genetic contribution of selected SNPs to COPD susceptibility. RESULTS: The AC genotype of NLRP3 rs1539019 significantly decreased COPD risk compared with CC genotype (adjusted OR = 0.508, 95% CI 0.336-0.767). In the stratification analyses, the AC genotype significantly decreased the risk of COPD in subjects aged 60 and over (p=0.005; adjusted OR = 0.553; 95% CI 0.366-0.835) with current smoking status (p=0.002; adjusted OR = 0.419; 95% CI 0.240-0.732) when compared with AA+CC genotype. Moreover, a significantly decreased risk for GOLD III COPD was found in genotype AC of NLRP3 rs1539019 (p=0.006; adjusted OR = 0.502; 95% CI 0.306-0.822). CONCLUSIONS: Our present study revealed that the genotype AC of NLRP3 rs1539019 is related to a decreased risk of COPD in a Chinese Han population, a large-sample, multi-center, multi-ethnic study is needed to further confirm our study.

Nuclear Vav3 is required for polycomb repression complex-1 activity in B-cell lymphoblastic leukemogenesis.

Acute B-cell lymphoblastic leukemia (B-ALL) results from oligo-clonal evolution of B-cell progenitors endowed with initiating and propagating leukemia properties. The activation of both the Rac guanine nucleotide exchange factor (Rac GEF) Vav3 and Rac GTPases is required for leukemogenesis mediated by the oncogenic fusion protein BCR-ABL. Vav3 expression becomes predominantly nuclear upon expression of BCR-ABL signature. In the nucleus, Vav3 interacts with BCR-ABL, Rac, and the polycomb repression complex (PRC) proteins Bmi1, Ring1b and Ezh2. The GEF activity of Vav3 is required for the proliferation, Bmi1-dependent B-cell progenitor self-renewal, nuclear Rac activation, protein interaction with Bmi1, mono-ubiquitination of H2A(K119) (H2AK119Ub) and repression of PRC-1 (PRC1) downstream target loci, of leukemic B-cell progenitors. Vav3 deficiency results in de-repression of negative regulators of cell proliferation and repression of oncogenic transcriptional factors. Mechanistically, we show that Vav3 prevents the Phlpp2-sensitive and Akt (S473)-dependent phosphorylation of Bmi1 on the regulatory residue S314 that, in turn, promotes the transcriptional factor reprogramming of leukemic B-cell progenitors. These results highlight the importance of non-canonical nuclear Rho GTPase signaling in leukemogenesis.

Radiomics-Based Machine Learning for Outcome Prediction in a Multicenter Phase II Study of Programmed Death-Ligand 1 Inhibition Immunotherapy for Glioblastoma.

BACKGROUND AND PURPOSE: Imaging assessment of an immunotherapy response in glioblastoma is challenging due to overlap in the appearance of treatment-related changes with tumor progression. Our purpose was to determine whether MR imaging radiomics-based machine learning can predict progression-free survival and overall survival in patients with glioblastoma on programmed death-ligand 1 inhibition immunotherapy. MATERIALS AND METHODS: Post hoc analysis was performed of a multicenter trial on the efficacy of durvalumab in glioblastoma (n = 113). Radiomics tumor features on pretreatment and first on-treatment time point MR imaging were extracted. The random survival forest algorithm was applied to clinical and radiomics features from pretreatment and first on-treatment MR imaging from a subset of trial sites (n = 60-74) to train a model to predict long overall survival and progression-free survival and was tested externally on data from the remaining sites (n = 29-43). Model performance was assessed using the concordance index and dynamic area under the curve from different time points. RESULTS: The mean age was 55.2 (SD, 11.5) years, and 69% of patients were male. Pretreatment MR imaging features had a poor predictive value for overall survival and progression-free survival (concordance index = 0.472-0.524). First on-treatment MR imaging features had high predictive value for overall survival (concordance index = 0.692-0.750) and progression-free survival (concordance index = 0.680-0.715). CONCLUSIONS: A radiomics-based machine learning model from first on-treatment MR imaging predicts survival in patients with glioblastoma on programmed death-ligand 1 inhibition immunotherapy.

Mitotic protein kinase-driven crosstalk of machineries for mitosis and metastasis.

Accumulating evidence indicates that mitotic protein kinases are involved in metastatic migration as well as tumorigenesis. Protein kinases and cytoskeletal proteins play a role in the efficient release of metastatic cells from a tumor mass in the tumor microenvironment, in addition to playing roles in mitosis. Mitotic protein kinases, including Polo-like kinase 1 (PLK1) and Aurora kinases, have been shown to be involved in metastasis in addition to cell proliferation and tumorigenesis, depending on the phosphorylation status and cellular context. Although the genetic programs underlying mitosis and metastasis are different, the same protein kinases and cytoskeletal proteins can participate in both mitosis and cell migration/invasion, resulting in migratory tumors. Cytoskeletal remodeling supports several cellular events, including cell division, movement, and migration. Thus, understanding the contributions of cytoskeletal proteins to the processes of cell division and metastatic motility is crucial for developing efficient therapeutic tools to treat cancer metastases. Here, we identify mitotic kinases that function in cancer metastasis as well as tumorigenesis. Several mitotic kinases, namely, PLK1, Aurora kinases, Rho-associated protein kinase 1, and integrin-linked kinase, are considered in this review, as an understanding of the shared machineries between mitosis and metastasis could be helpful for developing new strategies to treat cancer.

Dicer promotes genome stability via the bromodomain transcriptional co-activator BRD4.

RNA interference is required for post-transcriptional silencing, but also has additional roles in transcriptional silencing of centromeres and genome stability. However, these roles have been controversial in mammals. Strikingly, we found that Dicer-deficient embryonic stem cells have strong proliferation and chromosome segregation defects as well as increased transcription of centromeric satellite repeats, which triggers the interferon response. We conducted a CRISPR-Cas9 genetic screen to restore viability and identified transcriptional activators, histone H3K9 methyltransferases, and chromosome segregation factors as suppressors, resembling Dicer suppressors identified in independent screens in fission yeast. The strongest suppressors were mutations in the transcriptional co-activator Brd4, which reversed the strand-specific transcription of major satellite repeats suppressing the interferon response, and in the histone acetyltransferase Elp3. We show that identical mutations in the second bromodomain of Brd4 rescue Dicer-dependent silencing and chromosome segregation defects in both mammalian cells and fission yeast. This remarkable conservation demonstrates that RNA interference has an ancient role in transcriptional silencing and in particular of satellite repeats, which is essential for cell cycle progression and proper chromosome segregation. Our results have pharmacological implications for cancer and autoimmune diseases characterized by unregulated transcription of satellite repeats.

[Clinical features of primary isolated chylopericardium: a retrospective review study].

Objective: To examine the clinical characteristics and abnormal reflux branches of primary isolated chylopericardium. Methods: Totally 43 patients with primary isolated chylopericardium at Department of Lymphatic Surgery, Affiliated Beijing Shijitan Hospital,Capital Medical University from June 2007 to January 2018 were recruited in this study. There were 21 males and 22 females, aging (23.0±15.9) years (range: 2 to 57 years). The levels of triglyceride, total cholesterol, total protein and albumin in pericardial effusion and blood were compared by paired-t test, and the characteristics of lymphatic system in direct lymphangiography and postoperative CT were analyzed. Results: Pericardial effusion was mainly milky white and monocytes, and 95.3%(41/43) were positive for Rivalta test. The level of triglyceride in pericardial effusion was significantly higher than that of blood ((9.67±5.11) mmol/L vs. (1.28±0.89) mmol/L, t=10.557, P<0.01), and the levels of total cholesterol ((2.19±0.52) mmol/L vs. (4.12±1.06) mmol/L, t=-3.732, P<0.01), total protein ((61.25±16.17) g/L vs. (68.26±8.30) g/L, t=-2.958, P=0.005) and albumin ((36.63±7.06) g/L vs. (42.32±4.73) g/L, t=-5.747, P<0.01) were significantly lower than that of blood. In the direct lymphangiography, the imaging of iliac and retroperitoneal lymphatics showed dilated or tortuous in 90.7% (39/43), the thoracoabdominal segment of thoracic duct showed dilation in 46.5% (20/43), and cervical thoracic duct imaging showed dilation in 44.2% (19/43) and stenosis in 55.8% (24/43). The image of lipiodol flowing into the vein showed obstruction at the venous angle. There were 60.5%(26/43) of the patients with lipiodol reflux through the bronchomediastinal trunk (type Ⅰ), 11.6%(5/43) with lipiodol diffusion to the pericardium through the abnormal pathway from the thoracic segment of the thoracic duct (type Ⅱ), while no communication pathway between the thoracic duct and the pericardial cavity (type Ⅲ) found in 27.9%(12/43). CT images obtained after the direct lymphangiography showed 34.9%(15/43) had abnormal distribution of lipiodol in pericardium, mediastinal lymph nodes and lung hilar lymph nodes, 46.5%(20/43) in mediastinal lymph nodes and lung hilar lymph nodes, 14.0%(6/43) only mediastinal lymph nodes, 4.6%(2/43) had no lipiodol in the above areas. Conclusions: Pericardial effusion compared with same period blood, has higher triglyceride, lower total cholesterol, total protein and albumin. The obstruction of the cervical segment of the thoracic duct and the formation of abnormal reflux branches would be corelative to primary isolated chylopericardium.

Fluctuation of BCR-ABL1 qPCRIS level beyond 0.1%IS after stopping tyrosine kinase inhibitor in chronic myeloid leukaemia patients with deep molecular response for at least two years.

Fluctuation of BCR-ABL1 real-time quantitative polymerase chain reaction in International Scale (qPCRIS) level below major molecular response (MMR) (0.1%IS) is a known phenomenon after stopping tyrosine kinase inhibitor (TKI) in chronic myeloid leukaemia (CML) patients who are attempting treatment free remission (TFR). We report here four cases of fluctuation beyond MMR during conduct of a Malaysia Stop TKI Trial (MSIT) to examine the validity of the commonly used relapse criterion - loss of MMR for one reading - aiming to provide evidence in setting relapse criteria for future CML patients who want to attempt TFR.

Reversible cerebral vasoconstriction syndrome: a comprehensive systematic review.

OBJECTIVE: We aimed to analyze clinical characteristics, treatment patterns, and prognosis of patients with reversible cerebral vasoconstriction syndrome (RCVS). MATERIALS AND METHODS: Two investigators independently searched PubMed and EMBASE, and 191 cases were included in this study. Information regarding demographics, triggering factors, brain imaging findings, treatment modalities, recurrence, and clinical outcome was collected. RESULTS: The mean age of the patients was 39.9 years, and 155 (81.2%) were female. The most common triggering factor for RCVS was an exposure to vasoactive substances (41.4%), followed by pregnancy/postpartum (20.9%), and sexual intercourse (10.5%). Multifocal stenosis (84.0%) and beading shape (82.4%) were the leading abnormal findings on angiography, while cerebral ischemic lesions (47.6%) and cerebral hemorrhage (mainly subarachnoid hemorrhage) (35.1%) were the main findings on brain computed tomography (CT)/magnetic resonance imaging (MRI). Calcium channel blockers (nimodipine/verapamil) were the most commonly used medications (44.5%) in the treatment of RCVS. Multivariate analysis identified that RCVS was precipitated by trauma/surgery/procedure (hazard ratio (HR): 3.29, 95% confidence interval (CI) (1.21-8.88), p=0.019), and presence of aphasia/neglect/apraxia during the acute phase of the disease (HR: 3.83, 95% CI (1.33-11.05), p=0.013) were found to be the two independent risk factors for residual neurological deficit after RCVS. CONCLUSIONS: In our systematic review, vasoactive substances were the most frequent triggers for RCVS, which was most commonly accompanied by angiographic findings of multifocal stenotic lesions. Patients with RCVS precipitated by trauma or surgical procedures and those with focal cortical deficits had a higher risk of residual neurological deficits, and these patients should closely be monitored.

Learning curve in robotic transabdominal preperitoneal (rTAPP) ventral hernia repair: a cumulative sum (CUSUM) analysis.

PURPOSE: rTAPP-VHR is a novel technique which may be added to a surgeon's armamentarium. We aim to evaluate the robotic transabdominal preperitoneal ventral hernia repair (rTAPP-VHR) learning curve based on operative times while accounting for peritoneal flap integrity. METHODS: We performed a retrospective analysis of a database collected over a 7-year period. Patients with primary ventral hernias were included and a cumulative sum analysis(CUSUM) was used to create learning curves for three subsets of operative times. A risk-adjusted CUSUM (RA-CUSUM) accounted for repair quality based on peritoneal flap completeness. The flap was considered as incomplete when peritoneal gaps were unable to be closed. RESULTS: 105 patients undergoing rTAPP-VHR were included. Learning curves were created for skin-to-skin, console, and off-console times. Patients were divided into three phases. In terms of skin-to-skin times, both phase 2&3 had a mean 11 min shorter than that of phase 1 (p = 0.0498, p = 0.0245, respectively), with a steady decrease after forty-six cases. An incomplete peritoneal flap was noted in 25/36 patients in phase 1, as compared to 5/24 and 5/45 patients in phase 2&3, respectively. When risk-adjusted for peritoneal flap completeness, gradually decreasing skin-to-skin times were observed after sixty-one cases. In terms of off-console times, the mean across three phases was 14 min, with marked improvement after forty-three cases. CONCLUSIONS: Forty-six cases were needed to achieve steadily decreasing operative times. We can assume that ensuring good-quality repairs, through maintenance of peritoneal flap integrity, was gradually improved after sixty-one cases. Moreover, familiarization with port placements and robotic docking was accomplished after forty-three cases.

A comparison of robotic mesh repair techniques for primary uncomplicated midline ventral hernias and analysis of risk factors associated with postoperative complications.

PURPOSE: We aim to compare short-term outcomes of robotic intraperitoneal onlay (rIPOM), transabdominal preperitoneal (rTAPP) and retromuscular (rRM) repair for uncomplicated midline primary ventral hernias (PVH) and determine risk factors associated with postoperative complications. METHODS: The three groups were compared in terms of pre-, intra-, and post-operative variables. Postoperative complications were assessed using previously validated classifications. Univariate analyses were conducted to determine which variables influence postoperative complications (up to 90 days), followed by a multivariate regression analysis revealing statistically important risk factors. RESULTS: A total of 269 patients who underwent robotic PVH repair patients were grouped as rIPOM (n = 90), rTAPP (n = 108), and rRM (n = 71). rRM repair allowed for the use of larger-sized meshes for larger defects; however, it was associated with higher-grade complications. rTAPP repair resulted in the lowest morbidity and offered the highest mesh-to-defect ratio for smaller-sized hernias. Operative time for the rRM group was longer. The rIPOM group had a higher morbidity, likely due to higher frequency of minor complications, as compared to rTAPP and rRM groups. Multivariate regression analysis revealed that coronary artery disease, absence of defect closure, intraperitoneally placed mesh, and skin-to-skin time (minutes) were significantly associated with postoperative complications. CONCLUSION: Robotic PVHR contributes multiple techniques to a surgeon's armamentarium, such as IPOM, TAPP, and RM mesh placements. Patient characteristics as well as the potential consequences of each technique need to be taken into consideration when deciding the appropriate approach for the repair of primary uncomplicated midline ventral hernias.

Propensity score matching analysis of short-term outcomes in robotic ventral hernia repair for patients with a body mass index above and below 35 kg/m2.

OBJECTIVE: The purpose of this study was to compare perioperative complications after robotic ventral hernia repair between patients with non-obese, class-I obesity with those with class-II or class-III obesity. BACKGROUND: Obesity is a growing epidemic and is considered as an independent risk factor for a multitude of perioperative complications. Laparoscopic ventral hernia repair has been shown as a safe and feasible approach in population with elevated body mass index (BMI). This study compared overall perioperative complications and surgical site events (SSEs) after robotic ventral hernia repair (RVHR) between patients with a BMI 35 kg/m2 or more and patients with a BMI lower than 35 kg/m2. METHODS: A retrospective cohort analysis was conducted with one-to-one propensity score matching (PSM) method to obtain balanced groups evaluating patients who underwent RVHR between February 2012 and June 2019 in a single institution. Preoperative, intraoperative, and postoperative variables were reviewed. Postoperative complications and morbidity were assessed using the Clavien-Dindo classification and comprehensive complication index (CCI®) score system. SSEs were compared. RESULTS: Our unmatched sample included 526 patients with an average BMI of 31.2 kg/m2. Of these, 29.8% (n = 160) patients were in high-BMI group (range 35-59.2). After PSM, 142 patients were assigned to each group. Both groups experienced similar complication rates during 90 days. Clavien-Dindo grades, CCI® scores, and SSEs did not differ between the two groups. CONCLUSION: RVHR in class-II and class-III obese patients is safe, feasible, and effective. In addition to this, it has comparable short-term outcomes with those non-obese and class-I obese patients.

A large multicenter cohort on the use of full-thickness resection device for difficult colonic lesions.

BACKGROUND: Introduction of the full-thickness resection device (FTRD) has allowed endoscopic resection of difficult lesions such as those with deep wall origin/infiltration or those located in difficult anatomic locations. The aim of this study is to assess the outcomes of the FTRD among its early users in the USA. METHODS: Patients who underwent endoscopic full-thickness resection (EFTR) for lower gastrointestinal tract lesions using the FTRD at 26 US tertiary care centers between 10/2017 and 12/2018 were included. Primary outcome was R0 resection rate. Secondary outcomes included rate of technical success (en bloc resection), achievement of histologic full-thickness resection (FTR), and adverse events (AE). RESULTS: A total of 95 patients (mean age 65.5 ± 12.6 year, 38.9% F) were included. The most common indication, for use of FTRD, was resection of difficult adenomas (non-lifting, recurrent, residual, or involving appendiceal orifice/diverticular opening) (66.3%), followed by adenocarcinomas (22.1%), and subepithelial tumors (SET) (11.6%). Lesions were located in the proximal colon (61.1%), distal colon (18.9%), or rectum (20%). Mean lesion diameter was 15.5 ± 6.4 mm and 61.1% had a prior resection attempt. The mean total procedure time was 59.7 ± 31.8 min. R0 resection was achieved in 82.7% while technical success was achieved in 84.2%. Histologically FTR was demonstrated in 88.1% of patients. There were five clinical AE (5.3%) with 2 (2.1%) requiring surgical intervention. CONCLUSIONS: Results from this first US multicenter study suggest that EFTR with the FTRD is a technically feasible, safe, and effective technique for resecting difficult colonic lesions.

Enhanced anticancer activity and endocytic mechanisms by polymeric nanocarriers of n-butylidenephthalide in leukemia cells.

PURPOSE: The purpose of this study was to investigate the antitumor mechanisms of n-butylidenephthalide (BP) and to further examine the delivery efficacy of polycationic liposome containing PEI and polyethylene glycol complex (LPPC)-encapsulated BP in leukemia cells. METHODS: MTS, flow cytometric and TUNEL assays were performed to assess cell viability and apoptosis. BP and BP/LPPC complex delivery efficiency was analyzed by full-wavelength fluorescent scanner and fluorescence microscope. The expressions of cell cycle- and apoptosis-related proteins were conducted by Western blotting. RESULTS: The results showed that BP inhibited leukemia cell growth by inducing cell cycle arrest and cell apoptosis. LPPC-encapsulated BP rapidly induced endocytic pathway activation, resulting in the internalization of BP into leukemia cells, causing cell apoptosis within 1 h. CONCLUSIONS: LPPC encapsulation enhanced the cytotoxic activity of BP and did not influence the effects of BP induction that suggested LPPC-encapsulated BP might be developed as anti-leukemia drugs in future.

Mechanisms of resistance to selective RET tyrosine kinase inhibitors in RET fusion-positive non-small-cell lung cancer.

BACKGROUND: Rearranged during transfection (RET) gene fusions are a validated target in non-small-cell lung cancer (NSCLC). RET-selective inhibitors selpercatinib (LOXO-292) and pralsetinib (BLU-667) recently demonstrated favorable antitumor activity and safety profiles in advanced RET fusion-positive NSCLC, and both have received approval by the US Food and Drug Administration for this indication. Insights into mechanisms of resistance to selective RET inhibitors remain limited. PATIENTS AND METHODS: This study was performed at five institutions. Tissue and/or cell-free DNA was obtained from patients with RET fusion-positive NSCLC after treatment with selpercatinib or pralsetinib and assessed by next-generation sequencing (NGS) or MET FISH. RESULTS: We analyzed a total of 23 post-treatment tissue and/or plasma biopsies from 18 RET fusion-positive patients who received an RET-selective inhibitor (selpercatinib, n = 10; pralsetinib, n = 7; pralsetinib followed by selpercatinib, n = 1, with biopsy after each inhibitor). Three cases had paired tissue and plasma samples, of which one also had two serial resistant tissue specimens. The median progression-free survival on RET inhibitors was 6.3 months [95% confidence interval 3.6-10.8 months]. Acquired RET mutations were identified in two cases (10%), both affecting the RET G810 residue in the kinase solvent front. Three resistant cases (15%) harbored acquired MET amplification without concurrent RET resistance mutations, and one specimen had acquired KRAS amplification. No other canonical driver alterations were identified by NGS. Among 16 resistant tumor specimens, none had evidence of squamous or small-cell histologic transformation. CONCLUSIONS: RET solvent front mutations are a recurrent mechanism of RET inhibitor resistance, although they occurred at a relatively low frequency. The majority of resistance to selective RET inhibition may be driven by RET-independent resistance such as acquired MET or KRAS amplification. Next-generation RET inhibitors with potency against RET resistance mutations and combination strategies are needed to effectively overcome resistance in these patients.

The dynamics of gas-bubble formation at saturated conditions in porous media flow.

We investigate the stability of gas bubbles formed at saturated (bubble-point) conditions during two-component ([Formula: see text], [Formula: see text]O), two-phase (gas, liquid) flow by developing and analyzing a [Formula: see text] dynamical system describing flow through a single pore to study the dynamics of gas bubble formation and evolution. Our analysis indicates that three regimes occur at conditions pertinent to petroleum reservoirs. These regimes correspond to a critical point changing type from an unstable node to an unstable spiral and then to a stable spiral as flow rates increase. In the stable spiral case gas bubbles will achieve a steady-state finite size only if they form within the attractor region of the stable spiral. Otherwise, all gas bubbles that form undergo, possibly oscillatory, growth and then dissolve completely. Under steady flow conditions, this formation and dissolution repeats cyclically.

CRISPR-mediated promoter de/methylation technologies for gene regulation.

DNA methylation on cytosines of CpG dinucleotides is well established as a basis of epigenetic regulation in mammalian cells. Since aberrant regulation of DNA methylation in promoters of tumor suppressor genes or proto-oncogenes may contribute to the initiation and progression of various types of human cancer, sequence-specific methylation and demethylation technologies could have great clinical benefit. The CRISPR-Cas9 protein with a guide RNA can target DNA sequences regardless of the methylation status of the target site, making this system superb for precise methylation editing and gene regulation. Targeted methylation-editing technologies employing the dCas9 fusion proteins have been shown to be highly effective in gene regulation without altering the DNA sequence. In this review, we discuss epigenetic alterations in tumorigenesis as well as various dCas9 fusion technologies and their usages in site-specific methylation editing and gene regulation.