Cell death in cancer chemotherapy using taxanes

Cancer cells evolve to be refractory to the intrinsic programmed cell death mechanisms, which ensure cellular tissue homeostasis in physiological conditions. Chemotherapy using cytotoxic drugs seeks to eliminate cancer cells but spare non-cancerous host cells by exploring a likely subtle difference between malignant and benign cells. Presumably, chemotherapy agents achieve efficacy by triggering programmed cell death machineries in cancer cells. Currently, many major solid tumors are treated with chemotherapy composed of a combination of platinum agents and taxanes. Platinum agents, largely cis-platin, carboplatin, and oxaliplatin, are DNA damaging agents that covalently form DNA addicts, triggering DNA repair response pathways. Taxanes, including paclitaxel, docetaxel, and cabazitaxel, are microtubule stabilizing drugs which are often very effective in purging cancer cells in clinical settings. Generally, it is thought that the stabilization of microtubules by taxanes leads to mitotic arrest, mitotic catastrophe, and the triggering of apoptotic programmed cell death. However, the precise mechanism(s) of how mitotic arrest and catastrophe activate the caspase pathway has not been established. Here, we briefly review literature on the involvement of potential cell death mechanisms in cancer therapy. These include the classical caspase-mediated apoptotic programmed cell death, necroptosis mediated by MLKL, and pore forming mechanisms in immune cells, etc. In particular, we discuss a newly recognized mechanism of cell death in taxane-treatment of cancer cells that involves micronucleation and the irreversible rupture of the nuclear membrane. Since cancer cells are commonly retarded in responding to programmed cell death signaling, stabilized microtubule bundle-induced micronucleation and nuclear membrane rupture, rather than triggering apoptosis, may be a key mechanism accounting for the success of taxanes as anti-cancer agents.

Observation of a Strongly Isospin-Mixed Doublet in ^{26}Si via β-Delayed Two-Proton Decay of ^{26}P

β decay of proton-rich nuclei plays an important role in exploring isospin mixing. The β decay of ^{26}P at the proton drip line is studied using double-sided silicon strip detectors operating in conjunction with high-purity germanium detectors. The T=2 isobaric analog state (IAS) at 13 055 keV and two new high-lying states at 13 380 and 11 912 keV in ^{26}Si are unambiguously identified through β-delayed two-proton emission (β2p). Angular correlations of two protons emitted from ^{26}Si excited states populated by ^{26}P β decay are measured, which suggests that the two protons are emitted mainly sequentially. We report the first observation of a strongly isospin-mixed doublet that deexcites mainly via two-proton decay. The isospin mixing matrix element between the ^{26}Si IAS and the nearby 13 380-keV state is determined to be 130(21) keV, and this result represents the strongest mixing, highest excitation energy, and largest level spacing of a doublet ever observed in β-decay experiments.

Functions and therapeutic potentials of exosomes in osteosarcoma

Osteosarcoma is a primary malignant tumor of the skeleton with the morbidity of 2.5 in 1 million. The regularly on-set is in the epiphysis of the extremities with a high possibility of early metastasis, rapid progression, and poor prognosis. The survival rate of patients with metastatic or recurrent osteosarcoma remains low, and novel diagnostic and therapeutic methods are urgently needed. Exosomes are extracellular vesicles 30-150 nm in diameter secreted by various cells that are widely present in various body fluids. Exosomes are abundant in biologically active components such as proteins, nucleic acids, and lipids. Exosomes participate in numerous physiological and pathological processes via intercellular substance exchange and signaling. This review presents the novel findings of exosomes in osteosarcoma in diagnosis, prognosis, and therapeutic aspects.

Rationale for combination of paclitaxel and CDK4/6 inhibitor in ovarian cancer therapy — non-mitotic mechanisms of paclitaxel

Taxanes and CDK4/6 inhibitors (CDK4/6i) are two families of successful anti-mitotic drugs used in the treatment of solid tumors. Paclitaxel, representing taxane compounds, has been used either alone or in combination with other agents (commonly carboplatin/cisplatin) in the treatment of many solid tumors including ovarian, breast, lung, prostate cancers, and Kaposi’s sarcoma. Paclitaxel has been routinely prescribed in cancer treatment since the 1990s, and its prominent role is unlikely to be replaced in the foreseeable future. Paclitaxel and other taxanes work by binding to and stabilizing microtubules, causing mitotic arrest, aberrant mitosis, and cell death. CDK4/6i (palbociclib, ribociclib, abemaciclib) are relatively new cell cycle inhibitors that have been found to be effective in breast cancer treatment, and are currently being developed in other solid tumors. CDK4/6i blocks cell cycle progression at the G1 phase, resulting in cell death by mechanisms not yet fully elucidated. At first glance, paclitaxel and CDK4/6i are unlikely synergistic agents as both are cell cycle inhibitors that work at different phases of the cell cycle, and few clinical trials have yet considered adding CDK4/6i to existing paclitaxel chemotherapy. However, recent findings suggest the importance of a non-mitotic mechanism of paclitaxel in cancer cell death and pre-clinical data support rationale for a strategic paclitaxel and CDK4/6i combination. In mouse tumor model studies, drug sequencing resulted in differential efficacy, indicating complex biological interactions of the two drugs. This article reviews the rationales of combining paclitaxel with CDK4/6i as a potential therapeutic option in recurrent ovarian cancer.

[Several issues on surgical treatment for adenocarcinoma of esophagogastric junction]

There are several controversies and issues in the surgical treatment of esophagogastric junction (AEG) currently. The Siewert classification and TNM staging system are commonly used to assist clinical decision and prognosis prediction. Generally, transthoracic procedure is more suitable for Siewert Ⅰ type and longer esophageal invasion patients, while transhiatal is more suitable for Siewert Ⅲ type patients. The optimal extent of lymph node dissection for AEG should be based on tumor location and esophageal invasion range. The extent of surgical resection and the method of digestive tract reconstruction should be based on the principle of radical resection and surgical safety, and the postoperative life quality of patients should be fully considered. Roux-en-Y anastomosis is the most common and efficient anastomosis after total gastrectomy, while double tract anastomosis is recommended by many experts after proximal gastrectomy. With the continuous advancement of minimally invasive techniques, experienced centers and teams can perform digestive tract reconstruction under total laparoscopy. In the future, more high-quality studies are expected to provide evidence-based medical evidence for AEG's surgical treatment decisions.

Low Intensity Ultrasound as an Antidote to Taxane/Paclitaxel-induced Cytotoxicity

The taxane family of compounds, including Taxol/paclitaxel and Taxotere/docetaxel, are surprisingly successful drugs used in combination or alone for the treatment of most major solid tumors, especially metastatic cancer. The drugs are commonly used in regimen with other agents (often platinum drugs) as frontline treatment, or used as a single agent in a dose dense regimen for recurrent cancer. The major side effects of taxanes are peripheral neuropathy, alopecia, and neutropenia, which are grave burden for patients and limit the full potential of the taxane drugs. Especially in the current treatment protocol for peripheral neuropathy, taxane dosage is reduced once the symptoms present, resulting in the loss of full or optimal cancer killing activity.

Substantial efforts have been made to address the problem of cytotoxic side effects of taxanes, though strategies remain very limited. Following administration of the taxane compound by infusion, taxane binds to cellular microtubules and is sequestered within the cells for several days. Taxane stabilizes and interferes with microtubule function, leading to ultimate death of cancer cells, but also damages hair follicles, peripheral neurons, and hemopoietic stem cells. Currently, cryo-treatment is practiced to limit exposure and side effects of the drug during infusion, though the effectiveness is uncertain or limited.

A recent laboratory finding may provide a new strategy to counter taxane cytotoxicity, that a brief exposure to low density ultrasound waves was sufficient to eliminate paclitaxel cytotoxicity cells in culture by transiently breaking microtubule filaments, which were then relocated to lysosomes for disposal. Thus, ultrasonic force to break rigid microtubules is an effective solution to counter taxane cytotoxicity. The discovery and concept of low intensity ultrasound as an antidote may have the potential to provide a practical strategy to counter paclitaxel-induced peripheral neuropathy and alopecia that resulted from chemotherapy.

Taxanes are a class of important drugs used in chemotherapy to treat several major cancers. This article reviews a new laboratory discovery that ultrasound can be used as an antidote for the peripheral cytotoxicity of taxane drugs and discusses the potential development and application of low intensity ultrasound to prevent side effects in chemotherapeutic treatment of cancer patients.

Exposure to low intensity ultrasound removes paclitaxel cytotoxicity in breast and ovarian cancer cells

BACKGROUND

Paclitaxel (Taxol) is a microtubule-stabilizing drug used to treat several solid tumors, including ovarian, breast, non-small cell lung, and pancreatic cancers. The current treatment of ovarian cancer is chemotherapy using paclitaxel in combination with carboplatin as a frontline agent, and paclitaxel is also used in salvage treatment as a second line drug with a dose intensive regimen following recurrence. More recently, a dose dense approach for paclitaxel has been used to treat metastatic breast cancer with success. Paclitaxel binds to beta tubulin with high affinity and stabilizes microtubule bundles. As a consequence of targeting microtubules, paclitaxel kills cancer cells through inhibition of mitosis, causing mitotic catastrophes, and by additional, not yet well defined non-mitotic mechanism(s).

RESULTS

In exploring methods to modulate activity of paclitaxel in causing cancer cell death, we unexpectedly found that a brief exposure of paclitaxel-treated cells in culture to low intensity ultrasound waves prevented the paclitaxel-induced cytotoxicity and death of the cancer cells. The treatment with ultrasound shock waves was found to transiently disrupt the microtubule cytoskeleton and to eliminate paclitaxel-induced rigid microtubule bundles. When cellular microtubules were labelled with a fluorescent paclitaxel analog, exposure to ultrasound waves led to the disassembly of the labeled microtubules and localization of the signals to perinuclear compartments, which were determined to be lysosomes.

CONCLUSIONS

We suggest that ultrasound disrupts the paclitaxel-induced rigid microtubule cytoskeleton, generating paclitaxel bound fragments that undergo degradation. A new microtubule network forms from tubulins that are not bound by paclitaxel. Hence, ultrasound shock waves are able to abolish paclitaxel impact on microtubules. Thus, our results demonstrate that a brief exposure to low intensity ultrasound can reduce and/or eliminate cytotoxicity associated with paclitaxel treatment of cancer cells in cultures.

New α-Emitting Isotope ^{214}U and Abnormal Enhancement of α-Particle Clustering in Lightest Uranium Isotopes

A new α-emitting isotope ^{214}U, produced by the fusion-evaporation reaction ^{182}W(^{36}Ar,4n)^{214}U, was identified by employing the gas-filled recoil separator SHANS and the recoil-α correlation technique. More precise α-decay properties of even-even nuclei ^{216,218}U were also measured in the reactions of ^{40}Ar, ^{40}Ca beams with ^{180,182,184}W targets. By combining the experimental data, improved α-decay reduced widths δ^{2} for the even-even Po-Pu nuclei in the vicinity of the magic neutron number N=126 are deduced. Their systematic trends are discussed in terms of the N_{p}N_{n} scheme in order to study the influence of proton-neutron interaction on α decay in this region of nuclei. It is strikingly found that the reduced widths of ^{214,216}U are significantly enhanced by a factor of two as compared with the N_{p}N_{n} systematics for the 84≤Z≤90 and N<126 even-even nuclei. The abnormal enhancement is interpreted by the strong monopole interaction between the valence protons and neutrons occupying the π1f_{7/2} and ν1f_{5/2} spin-orbit partner orbits, which is supported by the large-scale shell model calculation.

Dynamic conversion of cell sorting patterns in aggregates of embryonic stem cells with differential adhesive affinity

BACKGROUND

Mammalian early development comprises the proliferation, differentiation, and self-assembly of the embryonic cells. The classic experiment undertaken by Townes and Holtfreter demonstrated the ability of dissociated embryonic cells to sort and self-organize spontaneously into the original tissue patterns. Here, we further explored the principles and mechanisms underlying the phenomenon of spontaneous tissue organization by studying aggregation and sorting of mouse embryonic stem (ES) cells with differential adhesive affinity in culture.

RESULTS

As observed previously, in aggregates of wild-type and E-cadherin-deficient ES cells, the cell assemblies exhibited an initial sorting pattern showing wild-type cells engulfed by less adhesive E-cadherin-deficient ES cells, which fits the pattern predicted by the differential adhesive hypothesis proposed by Malcom Steinberg. However, in further study of more mature cell aggregates, the initial sorting pattern reversed, with the highly adhesive wild-type ES cells forming an outer shell enveloping the less adhesive E-cadherin-deficient cells, contradicting Steinberg's sorting principle. The outer wild-type cells of the more mature aggregates did not differentiate into endoderm, which is known to be able to sort to the exterior from previous studies. In contrast to the naive aggregates, the mature aggregates presented polarized, highly adhesive cells at the outer layer. The surface polarity was observed as an actin cap contiguously spanning across the apical surface of multiple adjacent cells, though independent of the formation of tight junctions.

CONCLUSIONS

Our experimental findings suggest that the force of differential adhesive affinity can be overcome by even subtle polarity generated from strong bilateral ligation of highly adhesive cells in determining cell sorting patterns.

Breaking malignant nuclei as a non-mitotic mechanism of taxol/paclitaxel

Discovered in a large-scale screening of natural plant chemicals, Taxol/paclitaxel and the taxane family of compounds are surprisingly successful anti-cancer drugs, used in treatment of the majority of solid tumors, and especially suitable for metastatic and recurrent cancer. Paclitaxel is often used in combination with platinum agents and is administrated in a dose dense regimen to treat recurrent cancer. The enthusiasm and clinical development were prompted by the discovery that Taxol binds beta-tubulins specifically found within microtubules and stabilizes the filaments, and consequently inhibits mitosis. However, questions on how paclitaxel suppresses cancer persist, as other specific mitotic inhibitors are impressive in pre-clinical studies but fail to achieve significant clinical activity. Thus, additional mechanisms, such as promoting mitotic catastrophe and impacting non-mitotic targets, have been proposed and studied. A good understanding of how paclitaxel, and additional new microtubule stabilizing agents, kill cancer cells will advance the clinical application of these common chemotherapeutic agents. A recent study provides a potential non-mitotic mechanism of paclitaxel action, that paclitaxel-induced rigid microtubules act to break malleable cancer nuclei into multiple micronuclei. Previous studies have established that cancer cells have a less sturdy, more pliable nuclear envelope due to the loss or reduction of lamin A/C proteins. Such changes in nuclear structure provide a selectivity for paclitaxel to break the nuclear membrane and kill cancer cells over non-neoplastic cells that have a sturdier nuclear envelope. The formation of multiple micronuclei appears to be an important aspect of paclitaxel in the killing of cancer cells, either by a mitotic or non-mitotic mechanism. Additionally, by binding to microtubule, paclitaxel is readily sequestered and concentrated within cells. This unique pharmacokinetic property allows the impact of paclitaxel on cells to persist for several days, even though the circulating drug level is much reduced following drug administration/infusion. The retention of paclitaxel within cells likely is another factor contributing to the efficacy of the drugs. Overall, the new understanding of Taxol/paclitaxel killing mechanism-rigid microtubule-induced multiple micronucleation-will likely provide new strategies to overcome drug resistance and for rational drug combination.

Large Isospin Asymmetry in ^{22}Si/^{22}O Mirror Gamow-Teller Transitions Reveals the Halo Structure of ^{22}Al

β-delayed one-proton emissions of ^{22}Si, the lightest nucleus with an isospin projection T_{z}=-3, are studied with a silicon array surrounded by high-purity germanium detectors. Properties of β-decay branches and the reduced transition probabilities for the transitions to the low-lying states of ^{22}Al are determined. Compared to the mirror β decay of ^{22}O, the largest value of mirror asymmetry in low-lying states by far, with δ=209(96), is found in the transition to the first 1^{+} excited state. Shell-model calculation with isospin-nonconserving forces, including the T=1, J=2, 3 interaction related to the s_{1/2} orbit that introduces explicitly the isospin-symmetry breaking force and describes the loosely bound nature of the wave functions of the s_{1/2} orbit, can reproduce the observed data well and consistently explain the observation that a large δ value occurs for the first but not for the second 1^{+} excited state of ^{22}Al. Our results, while supporting the proton-halo structure in ^{22}Al, might provide another means to identify halo nuclei.

[Analysis on the project personnel's attitude and its influential factors of 23-valent pneumococcal polysaccharide vaccination program for the elderly in Shanghai]

Objective: To understand the project personnel's attitude towards the 23-valent pneumococcal polysaccharide vaccination program for the elderly in Shanghai and its conversion to routine vaccination and to explore its influential factors, so as to provide reference for the further development of the program. Methods: In 2016, a one-to-one questionnaire survey was conducted among the people involved in the project in the 9 districts of Shanghai and the data of demographic characteristics, cognition of pneumococcal pneumonia and PPV23, evaluation of the project, support rate of the project and its conversion to routine vaccination of the project personnel were collected. Results: Among the 2005 respondents, 28.6% (574 persons) of them were male, 85.5% (1 714 persons) of them supported the free vaccination for the elderly, and 69.5% of them (1 394 persons) supported the routine vaccination. For the 23-valent pneumococcal polysaccharide vaccination program, people under 55 years old, in Qingpu District, with poor cognition of pneumonia and 23-valent pneumococcal polysaccharide vaccine (PPV23) or having lower evaluation of the project's scientificity or enforceability had lower support rate than others, and the OR (95%CI) were 0.38 (0.19-0.75), 0.21 (0.10-0.43), 0.16 (0.06-0.41) and 0.26 (0.10-0.69). People believing that the elderly were susceptible to pneumococcal pneumonia and PPV23 was safe and reliable, and those who were willing to vaccinate the elderly at home had higher support rate, and the OR (95%CI) were 2.30 (1.18-4.47), 2.84 (1.62-4.69) and 5.60 (3.74-8.38). For the program's conversion to routine vaccination, people under 35 years old, in Qingpu District, in the vaccination clinic, and those believing that the project was not scientific and difficult to implement had low support rate, and the OR (95%CI) were 0.56 (0.32-0.98), 0.48 (0.26-0.89), 0.26 (0.12-0.59), 0.58 (0.42-0.79) and 0.50 (0.30-0.81); people with technical secondary school or senior school, in Jiading, Putuo or Minhang District, believing that PPV23 was effective in the prevention of pneumococcal pneumonia in the elderly, and those who were willing to vaccinate the elderly with PPV23 had higher support rate, and the OR (95%CI) were 1.63 (1.11-2.39), 2.28 (1.71-3.03), 1.69 (1.25-2.28) and 4.10 (2.86-5.88). Conclusion: The support rate of pneumococcal vaccination project for the elderly in Shanghai needs to be improved, especially its conversion to the routine vaccination.

Short-Lived α-Emitting Isotope ^{222}Np and the Stability of the N=126 Magic Shell

A new, very short-lived neutron-deficient isotope ^{222}Np was produced in the complete-fusion reaction ^{187}Re(^{40}Ar,5n)^{222}Np, and observed at the gas-filled recoil separator SHANS. The new isotope ^{222}Np was identified by employing a recoil-α correlation measurement, and six α-decay chains were established for it. The decay properties of ^{222}Np with E_{α}=10016(33)  keV and T_{1/2}=380_{-110}^{+260}  ns were determined experimentally. The α-decay systematics of Np isotopes is improved by adding the new data for ^{222}Np, which validates the N=126 shell effect in Np isotopes. The evolution of the N=126 shell closure is discussed in the neutron-deficient nuclei up to Np within the framework of α-decay reduced width.

[Clinical significance of serum squamous cell carcinoma antigen in patients with early cervical squamous cell carcinoma]

Objective: To explore the clinical significance of serum squamous cell carcinoma antigen (SCC-Ag) in early cervical squamous cell carcinoma. Methods: The clinicopathological data and follow-up information of 1435 patients with stage ⅠA2-ⅡA cervical squamous cell carcinoma were collected. The correlation between serum SCC-Ag level and clinicopathological feature and prognosis were analyzed. The best cut-off of serum SCC-Ag for predicting pelvic lymph node metastasis and survival of cervical squamous cell carcinoma patients were also identified. Results: The result of univariate analysis showed that The International Federation of Gynecology and Obstetrics (FIGO) staging, tumor size, depth of cervical stromal invasion, lymphovascular space involvement, pelvic lymph node metastasis, common iliac lymph node metastasis and para-aortic lymph node metastasis were significantly related with serum SCC-Ag level (all P<0.05). The result of multivariate logistic regression analysis showed that tumor size, depth of cervical stromal invasion, pelvic lymph node metastasis and common iliac lymph node metastasis were the independent risk factors of preoperative serum SCC-Ag>2.65 ng/ml (all P<0.001). Multivariate Cox regression analysis showed that lymphovascular space involvement, SCC-Ag>3.15 ng/ml, common iliac lymph node metastasis and tumor size >4 cm were the independent prognostic risk factors (all P<0.05). The univariate analysis showed that, the tumor size, FIGO stage, depth of cervical stromal invasion and SCC-Ag level were significantly related with the recurrence of 1 096 patients without postoperative high risk factors (all P<0.05). Multivariate logistic regression analysis showed that FIGO stage (OR=1.671) and SCC-Ag>2.65 ng/ml (OR=4.490) were the independent risk factors for recurrence (both P<0.05). The best cut off of SCC-Ag for predicting early postoperative cervical lymph node metastasis of cervical squamous cell carcinoma was 2.65 ng/ml, the sensitivity was 60.8%, the specificity was 71.8%. The best cut off of SCC-Ag for predicting prognosis of cervical squamous cell carcinoma was 3.15 ng/ml, the sensitivity was 53.5%, the specificity was 71.1%. Conclusions: Preoperative serum squamous cell carcinoma antigen is an independent prognostic risk factor of survival of patients with early cervical squamous cell carcinoma, and is significantly related with recurrence of patients without postoperative high-risk factors. It can be used as a reference factor for postoperative adjuvant radiotherapy.

[Correlation between endogenous EPO levels and electrocardiogram scatter plot changes in patients with coronary heart disease and autonomic nerve function injury]

Objective: To analyze the correlation between endogenous EPO levels and electrocardiogram scatter plot changes in patients with coronary heart disease and autonomic nerve function injury. Methods: Forty-eight patients who underwent coronary arteriography (CAG) inspection due to chronic coronary heart diseases were selected from July 2015 to October 2015. All of them were evaluated by the Ewing standard autonomic nervous function test, and were divided into Ewing(+) group and Ewing(-) group according to the results of the test. The clinical data of the patients was collected and venous blood was extracted to detect EPO level. Results: The EPO level of Ewing (+) group ((13±3) mIU/ml) was significantly higher than that of Ewing (-) group ((10±3) mIU/ml). The Lorenz scatter plot comet shapes between the two groups had a significant difference. As for the quantitative indicators of Lorenz scatterplot, length of the Ewing (+) group ((147±22) ms) was shorter than that of the Ewing (-) group ((164±24) ms) and there was no significant differences in the width between the two groups. EPO level was negatively correlated with length in both groups (r=-0.427, P=0.002), but not with width (r=0.091, P=0.539). Binary logistic regression analysis showed that EPO (OR=1.394) and diastolic blood pressure (OR=1.091) were risk factors for autonomic nervous function damage. Length (OR=0.934) was a protective factor for autonomic nervous function. ROC curve analysis showed that the area under the EPO curve was 0.737 and that under the length curve was 0.719. Conclusions: The endogenous EPO levels are associated with the changes of electrocardiogram scatter plot in patients with coronary heart disease and autonomic nerve function injury. EPO and length of scatter plot have the similar diagnostic value on predicting of autonomic nerve function injury.

[Influencing factors for non/low-response to hepatitis-B vaccine in infants of HBsAg positive mothers]

Objective: To investigate the influencing factors for non/low-response to hepatitis B vaccine in infants of HBsAg-positive mothers. Methods: A total of 286 HBsAg-positive pregnant women and their infants were recruited from the Third People's Hospital of Taiyuan during July 2011 to January 2013. The infants were immunized with hepatitis B vaccine according to the 0-1-6 month vaccination schedule and followed up for 12 months. The serum HBV DNA level of mothers, neonates and infants were detected by electro chemilum inescence immunoassay kits and fluorescene quantiative polymerase chain rection. Results: Among 286 infants, the rate of non/low-response to hepatitis B vaccine was 18.53% (53/286). Non-conditional logistic regression analysis indicated that the mother's HBV DNA level ≥1×10(7) copies/ml (OR=2.592, 95%CI: 1.121-5.996) and natural birth (OR=1.932, 95%CI: 1.021-3.654) were the risk factors for non/low-response to hepatitis B vaccine, the risks were 2.592 times and 1.932 times higher compared with the infants whose mothers were HBV DNA negative and the infants whose mothers had cesarean delivery. There was no multiplicative or additive interaction between high HBV DNA load and natural birth (OR=1.055, 95%CI: 0.209-5.321), (RERI=1.617, 95%CI: -4.038-7.272; AP=0.364, 95%CI: -0.527-1.225; SI=1.195, 95%CI: 0.270-13.135). After stratified analysis of mother's HBV DNA level, delivery mode of mothers was not associated with non/low-response of their infants. Conclusion: The mother's load of HBV DNA≥1×10(7) copies/ml might be the factor for non/low-response to hepatitis B vaccine in infants of HBsAg positive mothers.

[Relationship between the HBsAg-positive infection status of mothers and the non/low-response to hepatitis B vaccine of their infants]

Objective: To explore the relationship between the status of HBsAg-positive infection of mothers and the non/low-response to hepatitis B vaccine of their infants. Methods: A total of 225 pairs of mothers and their infants were recruited in our cohort from June 2011 to July 2013. Infants were given three doses of hepatitis B vaccine at hour 24, first month and month 6(t)h respectively and were followed up for one year after birth. HBV serological markers and HBV DNA in the peripheral blood of both mothers and infants were detected by Electro-chemiluminescence immunoassay and fluorescence quantitative Polymerase Chain Reaction. Results: Six HBV infection models were detected in HBsAg-positive mothers, and "HBsAg (+), HBeAg (+), anti-HBc (+)" (model one) and "HBsAg (+), anti-HBe (+), anti-HBc (+)" (model two) accounted for 92.5%(208/225) of all the models. Rate of non/low-response to hepatitis B vaccine in infants born to mothers in model one was lower than those in model two, the differences are statistically significant (χ(2)=4.80, P=0.029). The rate of non/low-response to hepatitis B vaccine in infants showed a downward trend with the rising of HBeAg level in their mothers (χ(2)=4.86, P=0.028). Results from the unconditional logistic regression analysis showed that the HBeAg of the HBsAg-positive mothers was significantly correlated with the low risk of non/low-response to hepatitis B vaccine in infants (OR=0.598, 95%CI: 0.378-0.947). The positive rate of serum HBV DNA in HBsAg-positive mothers was 54.2%, while the rate of non/low-response to hepatitis B vaccine in infants born to HBV DNA positive mothers was similar to those infants born to HBV DNA negative mothers (χ(2)=0.22, P=0.640). Conclusions: "HBsAg (+), HBeAg (+), anti-HBc (+)" and "HBsAg (+), anti-HBe(+), anti-HBc (+)" were the common models seen in HBsAg-positive mothers, and the rate of non/low-response to hepatitis B vaccine was different between the two models. HBeAg of HBsAg-positive mothers might have positive effects on the immune response to hepatitis B vaccine in infants but the mechanisms remained not clear. HBV DNA of the HBsAg-positive mothers did not seem to be correlated with the immune response to hepatitis B vaccine in infants.

Defective Nuclear Lamina in Aneuploidy and Carcinogenesis

Aneuploidy, loss or gain of whole chromosomes, is a prominent feature of carcinomas, and is generally considered to play an important role in the initiation and progression of cancer. In high-grade serous ovarian cancer, the only common gene aberration is the p53 point mutation, though extensive genomic perturbation is common due to severe aneuploidy, which presents as a deviant karyotype. Several mechanisms for the development of aneuploidy in cancer cells have been recognized, including chromosomal non-disjunction during mitosis, centrosome amplification, and more recently, nuclear envelope rupture at interphase. Many cancer types including ovarian cancer have lost or reduced expression of Lamin A/C, a structural component of the lamina matrix that underlies the nuclear envelope in differentiated cells. Several recent studies suggest that a nuclear lamina defect caused by the loss or reduction of Lamin A/C leads to failure in cytokinesis and formation of tetraploid cells, transient nuclear envelope rupture, and formation of nuclear protrusions and micronuclei during the cell cycle gap phase. Thus, loss and reduction of Lamin A/C underlies the two common features of cancer—aberrations in nuclear morphology and aneuploidy. We discuss here and emphasize the newly recognized mechanism of chromosomal instability due to the rupture of a defective nuclear lamina, which may account for the rapid genomic changes in carcinogenesis.

Overexpression and cytoplasmic localization of caspase-6 is associated with lamin A degradation in set of ovarian cancers

Background

In most women with ovarian cancer, the diagnosis occurs after dissemination of tumor cells beyond ovaries. Several molecular perturbations occur ahead of tumor initiation including loss of lamin A/C. Our hypothesis was that the loss of nuclear structural proteins A type lamins (lamin A/C) transcribed from LMNA gene and substrate for active caspase-6 maybe one of the molecular perturbations. Our objective is to investigate the association between the loss of lamin A/C and the overexpression of caspase-6 in ovarian cancer cells.

Method

Western blotting and immunofluorescence were used to analyze the expression of lamin A/C and active caspase-6 in normal human ovarian surface epithelial (HOSE) cells, immortalized human ovarian surface epithelial cells and a set of seven ovarian cancer cell lines (including OVCAR3, OVCAR5, and A2780). The activity of caspase-6 was measured by densitometry, fluorescence and flow cytometry. Immunohistochemistry was used to evaluate the expression of caspase-6 in set of ovarian cancer tissues previously reported to have lost lamin A/C.

Results

The results showed that HOSE cells expressed lamin A/C and no or low level of active caspase-6 while cancer cells highly expressed caspase-6 and no or low level of lamin A/C. The inhibition of caspase-6 activity in OVCAR3 cells increased lamin A but has no effect on lamin C; active caspase-6 was localized in the cytoplasm associated with the loss of lamin A.

Conclusion

Overexpression and cytoplasmic localization of caspase-6 in ovarian cancer cells may be involved in lamin A degradation and deficiency observed in some ovarian cancer cells.

[The protective effect of N-acetylcysteine on acute lung injury induced by PFIB inhalation]

Objective: To study the protective effect of N-acetylcysteine on acute lung injury induced by PFIB inhalation and its mechanism. Methods: Survival experiment: 48 male ICR (CD-1) mice were randomly divided into 4 groups, i. e., PFIB control group, NAC prevention group, NAC treatment group, and NAC prevention + treatment group, each group contains 12 animals. The mice of PFIB C group were exposed to PFIB without any treatment. The mice of NAC P group were exposed to PFIB 30min after NAC administration. The mice of NAC T group were exposed to PFIB 1h before NAC administration, The mice of NAC P+T group were administrated with NAC twice (30 min before and 1h after PFIB inhalation) . 150 mg/kg NAC was given by each time. The 7 days survival rate of mice after lethal dose PFIB exposure was observed. 18 male Wistar rats were randomly divided into 3 groups i.e., normal control group (N-C) , PFIB control group (PFIB-C) and NAC prevention group (NAC-P) , with each group contains 6 animals in the second experiment. The rats of N-C group received no treatment. The rats of NAC-P group and PFIB-C group were exposed to PFIB 30min after treatment of NAC (420 mg/Kg, i.p.) and saline, respectively. The respiratory functions of animals were tested before and 24 h after PFIB inhalation. The arterial blood gas was analyzed after rats were anesthetized 24 hours post sublethal dose PFIB exposure. Then samples of BALF, plasma and lung tissue were collected. Wet lung/body weight ratio, protein and phospholipid content in BALF, and T-SOD, GSH, GSH-Px in plasma and lung tissue were measured. The expression of Peroxiredoxin 2 was detected by Westernblot assay. Results: NAC prevention can significantly improve the survival of mice exposed to a lethal dose PFIB while NAC treatment is ineffective. Severe lung edema was observed in rats 24 h after PFIB exposure. Compared to N-C group, the wet lung/body weight ratio, protein and phospholipid content in BALF, and respiratory rate of PFIB control group all increased significantly (P<0.01) . The arterial oxygen partial pressure (PaO(2)) reduced significantly (P<0.05) . The GSH-Px activity in lung tissue reduced significantly (P<0.01) while the expression of Peroxiredoxin 2 increased significantly (P<0.01) . NAC prophylaxis significantly reduced the wet lung/body weight ratio, protein and phospholipid content in BALF, respiratory rate of rats exposed to PFIB (P<0.01) . Compared with PFIB-C group, the PaO(2) (P<0.05) and the activity of GSH-Px (P<0.01) and the expression of Peroxiredoxin 2 in lung tissue (P<0.01) were increased significantly. Conclusion: Acute lung injury induced by PFIB inhalation is related to oxidative stress caused by the stimulation to lung. induced and pulmonary subjected to stimulate the generation of exposure, NAC prevention can regulation of the redox system in lung tissue and protect target organ of the treated animals effectively.

Optimal parameters and location for diffusion tensor imaging in the diagnosis of carpal tunnel syndrome: a meta-analysis

AIM

To assess the diagnostic value of the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) of diffusion tensor imaging (DTI) at several anatomical locations in patients with carpal tunnel syndrome (CTS) to explore the optimal parameters and measurement location.

MATERIALS AND METHODS

A search was conducted using the PubMed, EBSCO, Ovid, Web of Science, and Cochrane databases to identify articles relevant to this study published before September 2017. Studies were selected and included according to strict eligibility criteria. Mean differences (MD) and 95% confidence intervals (CIs) were used to compare FA and ADC values between CTS patients and healthy subjects. Potential publication bias was investigated.

RESULTS

Eleven studies involving 349 CTS wrists and 278 controls were selected for the meta-analysis. A notable MD: was found for lowered FA at the level of the pisiform bone for CTS versus controls (MD: -0.11, 95% confidence interval [CI]: -1.14 to -0.07, z=5.83, p<0.001). A higher ADC was found at the pisiform bone and hamate bone levels for CTS versus controls (P: MD: 0.15, 95% CI: 0.10 to 0.20, z=5.98, p<0.001, H: MD: 0.15; 95% CI: 0.09 to 0.21, z=4.67, p<0.001).

CONCLUSIONS

The meta-analysis demonstrated a significant FA reduction and ADC increase in CTS patients. This result supports the use of DTI parameters in differentiating CTS patients from health subjects. The anatomical site for FA at the pisiform and ADC at the pisiform and hamate levels were more accessible than other sites for the diagnosis of CTS patients.

Renal compartment-specific genetic variation analyses identify new pathways in chronic kidney disease

Chronic kidney disease (CKD), a condition when the kidneys are unable to clear waste products, affects 700 million people globally. Genome-wide association (GWA) studies identified sequence variants for CKD; however, the biological basis of GWAS remains poorly understood. To address this issue, we created an expression quantitative trait loci (eQTL) atlas for the glomerular and tubular compartments of the human kidney. Integrating the CKD GWAS with eQTL, single-cell RNA sequencing and regulatory region maps, we identified novel genes for CKD. Putative causal genes were enriched for proximal tubule expression and endo-lysosomal function, where DAB2, an adaptor protein in the TGFβ pathway, formed a central node. Functional experiments confirmed that reducing Dab2 expression in renal tubules protected mice from CKD. In conclusion, compartment-specific eQTL analysis is an important avenue for the identification of novel genes and cellular pathways involved in CKD development and thus potential new opportunities for its treatment.

New biological research and understanding of Papanicolaou's test

The development of the Papanicolaou smear test by Dr. George Nicholas Papanicolaou (1883-1962) is one of the most significant achievements in screening for disease and cancer prevention in history. The Papanicolaou smear has been used for screening of cervical cancer since the 1950s. The test is technically straightforward and practical and based on a simple scientific observation: malignant cells have an aberrant nuclear morphology that can be distinguished from benign cells. Here, we review the scientific understanding that has been achieved and continues to be made on the causes and consequences of abnormal nuclear morphology, the basis of Dr. Papanicolaou's invention. The deformed nuclear shape is caused by the loss of lamina and nuclear envelope structural proteins. The consequences of a nuclear envelope defect include chromosomal numerical instability, altered chromatin organization and gene expression, and increased cell mobility because of a malleable nuclear envelope. HPV (Human Papilloma Virus) infection is recognized as the key etiology in the development of cervical cancer. Persistent HPV infection causes disruption of the nuclear lamina, which presents as a change in nuclear morphology detectable by a Papanicolaou smear. Thus, the causes and consequences of nuclear deformation are now linked to the mechanisms of viral carcinogenesis, and are still undergoing active investigation to reveal the details. Recently a statue was installed in front of the Papanicolaou's Cancer Research Building to honor the inventor. Remarkably, the invention nearly 60 years ago by Dr. Papanicolaou still exerts clinical impacts and inspires scientific inquiries.

GATA6 phosphorylation by Erk1/2 propels exit from pluripotency and commitment to primitive endoderm

The transcription factor GATA6 and the Fgf/Ras/MAPK signaling pathway are essential for the development of the primitive endoderm (PrE), one of the two lineages derived from the pluripotent inner cell mass (ICM) of mammalian blastocysts. A mutant mouse line in which Gata6-coding exons are replaced with H2BGFP (histone H2B Green Fluorescence Protein fusion protein) was developed to monitor Gata6 promoter activity. In the Gata6-H2BGFP heterozygous blastocysts, the ICM cells that initially had uniform GFP fluorescence signal at E3.5 diverged into two populations by the 64-cell stage, either as the GFP-high PrE or the GFP-low epiblasts (Epi). However in the GATA6-null blastocysts, the originally moderate GFP expression subsided in all ICM cells, indicating that the GATA6 protein is required to maintain its own promoter activity during PrE linage commitment. In embryonic stem cells, expressed GATA6 was shown to bind and activate the Gata6 promoter in PrE differentiation. Mutations of a conserved serine residue (S264) for Erk1/2 phosphorylation in GATA6 protein drastically impacted its ability to activate its own promoter. We conclude that phosphorylation of GATA6 by Erk1/2 compels exit from pluripotent state, and the phosphorylation propels a GATA6 positive feedback regulatory circuit to compel PrE differentiation. Our findings resolve the longstanding question on the dual requirements of GATA6 and Ras/MAPK pathway for PrE commitment of the pluripotent ICM.

[Relationship between HBeAg from HBsAg positive mothers and regulatory T cells in neonates and its influence on HBV intrauterine transmission]

Objective: To explore the relationship between HBeAg in HBsAg positive mothers and CD(4)(+)CD(25)(+)Foxp3(+)regulatory T cells (Treg) in newborns, as well as how they would influence the increasing risk on HBV intrauterine transmission. Methods: We collected information on general demographic characteristics and delivery on 270 HBsAg positive mothers and their newborns from the Third People's Hospital of Taiyuan. Fluorescence quantitative polymerase chain reaction (FQ-PCR) and chemiluminescence immunoassay (CLIA) were used to detect HBV DNA and HBV serological markers in peripheral blood from both mothers and neonates. The expression of Treg and other immune cells in peripheral blood of neonates were detected with flow cytometry (FCM). Results: Maternal HBeAg positive rates were associated with an increased risk of intrauterine transmission (OR=4.08, 95%CI: 1.89-8.82). Rates of Treg in newborns born to HBsAg-positive mothers were higher than that of the negative group (Z=2.29, P=0.022). Each pair of the subjects was assigned to five different groups according to the HBeAg titers of mothers. Frequencies of both Treg and HBeAg in newborns and HBV DNA in mothers between the above said 5 groups showed similar trends of changing patterns and the differences between groups were statistically significant(χ(2)=18.73, P<0.001; χ(2)=181.60, P<0.001; χ(2)=183.09, P<0.001). Results from partial correlation analysis showed that after adjusting for neonatal HBeAg and maternal HBV DNA, mother's HBeAg titers were positively related to the percentage of Treg in their newborns (r(s)=0.19, P=0.039). In addition, the frequencies of Treg were negatively correlated with pDC and CD(4)(+) T cell in their newborns (r(s)=-0.21, P=0.017; r(s)=-0.23, P=0.009). Conclusion: HBeAg from HBsAg positive mothers might have inhibited the function of neonatal DC cells and T cells to reduce the immune response to HBV by up-regulating the proportion of Treg and finally increased the risk of HBV intrauterine transmission.

Enhanced energy transfer in heterogeneous nanocrystals for near infrared upconversion photocurrent generation

The key to produce inorganic heterogeneous nanostructures, and to integrate multiple functionalities, is to enhance or at least retain the functionalities of different components of materials. However, this ideal scenario is often deteriorated at the interface of the heterogeneous nanostructures due to lattice mismatches, resulting in downgraded performance in most hybrid nanomaterials. Here, we report that there is a narrow window in controlling temperature in a Lewis acid-base reaction process to facilitate epitaxial alignment during the synthesis of hybrid nanomaterials. We demonstrate a perfectly fused NaYF₄:Yb,Tm@ZnO heterogeneous nanostructure, in which the semiconductor ZnO shell can be epitaxially grown onto lanthanide-doped upconversion nanoparticles. By achieving a matched crystal lattice, the interface defects and crystalline grain boundaries are minimized to enable more efficient energy transfer from the upconversion nanoparticles to the semiconductor, resulting in both enhanced upconversion luminescence intensity and superior photoelectrochemical properties. This strategy provides an outstanding approach to endow lanthanide-doped upconversion nanoparticles with versatile properties.

Is the Dispersion Relation Applicable for Exotic Nuclear Systems? The Abnormal Threshold Anomaly in the ^{6}He+^{209}Bi System

The threshold anomaly of the phenomenological potential has been known for a long time in nuclear reactions at energies around the Coulomb barrier, where the connection between the real and imaginary potentials is well described by the dispersion relation. However, this connection is not clear yet for some weakly bound nuclear systems, especially for reactions induced by exotic radioactive nuclei. In this study, precise optical potentials of the halo nuclear system ^{6}He+^{209}Bi were extracted via ^{208}Pb(^{7}Li,^{6}He) transfer reactions with energies measured downward to the extremely sub-barrier region. The real potential presents a bell-like shape around the barrier as a normal threshold anomaly in tightly bound nuclear systems. However, the imaginary potential shows an abnormal behavior: it increases first with energy decreasing below the barrier and then falls quickly down to 0. It is the first time the threshold of the imaginary potential has been determined in an exotic nuclear system. Moreover, experimental results show the dispersion relation is not applicable for this system, which may be a common phenomenon for exotic nuclear systems. We discuss possible explanations for such a peculiar behavior, but further study is still desired for the underlying physics.

[Effect of telbivudine on infants born to HBsAg-positive mothers with non-/hypo-response to hepatitis B vaccine during their second and third trimesters of pregnancy]

Objective: To explore the effect of telbivudine treatment in a prevention program on infants born to HBsAg-positive mothers with non-/hypo-responsiveness to hepatitis B vaccine. Methods: A retrospective cohort study with a total of 321 HBsAg-positive pregnant women and their infants enrolled, was conducted. The mothers were recruited from the Third People' s Hospital of Taiyuan, from July 2011 to January 2013. According to the situation of telbivudine intake in second and third trimesters of pregnancy, the participants were divided into two groups: with telbivudine-treated or as control. The neonates were followed up till the age of 12 months. Maternal, neonatal and infantile HBV-M together with HBV DNA in serum were measured using the electro-chemiluminescence immuno-assay (ECLIA) kits and fluorescence quantitative polymerase chain reaction (FQ-PCR) assay, respectively. Results: The rate of non-/hypo-response was 17.99%. After adjusting the potential confounding factors, the telbivudine treatment on HBsAg-positive mothers in the second and third trimesters of pregnancy seemed as the protective factor for non-/hypo-response to hepatitis B vaccine in infants (aRR=0.119, 95% CI: 0.014-0.974). Levels of IFN-γ and IL-10 in telbivudine-treated group were higher than those in the controls (aRR=8.684, 95%CI: 1.977-38.140; aRR=5.330, 95% CI: 1.278-22.236). When the serum levels of IFN-γ and IL-10 in neonatal peripheral blood were higher than 228.47 pg/ml and 174.05 pg/ml respectively, the infants were less likely to be non-/hypo-responsive to the hepatitis B vaccine (aRR=0.300, 95%CI: 0.105-0.857) (aRR= 0.104, 95% CI: 0.030-0.354). Conclusion: Telbivudine treatment provided for the HBsAg-positive mothers in second and third trimesters of pregnancy were less likely to develop non-/low-responsive to hepatitis B vaccine in infants since IFN-γ and IL-10 might have played a vital role in this process.

Pten facilitates epiblast epithelial polarization and proamniotic lumen formation in early mouse embryos

BACKGROUND

Phosphatase and tensin homologue on chromosome 10 (Pten), a lipid phosphatase originally identified as a tumor-suppressor gene, regulates the phosphoinositol 3 kinase signaling pathway and impacts cell death and proliferation. Pten mutant embryos die at early stages of development, although the particular developmental deficiency and the mechanisms are not yet fully understood.

RESULTS

We analyzed Pten mutant embryos in detail and found that the formation of the proamniotic cavity is impaired. Embryoid bodies derived from Pten-null embryonic stem cells failed to undergo cavitation, reproducing the embryonic phenotype in vitro. Analysis of embryoid bodies and embryos revealed a role of Pten in the initiation of the focal point of the epithelial rosette that develops into the proamniotic lumen, and in establishment of epithelial polarity to transform the amorphous epiblast cells into a polarized epithelium.

CONCLUSIONS

We conclude that Pten is required for proamniotic cavity formation by establishing polarity for epiblast cells to form a rosette that expands into the proamniotic lumen, rather than facilitating apoptosis to create the cavity. Developmental Dynamics 246:517-530, 2017. © 2017 Wiley Periodicals, Inc.

[Changes of productions of energy metabolism in masseter of rats induced by occlusal interference]

OBJECTIVE

To investigate the effect of occlusal interference on the energy metabolism of masticatory muscle by studying the changes of adenosine triphosphate (ATP), adenosine diphosphate (ADP), inosine monophosphate (IMP), phosphocreatine, creatine, lactate and pH level in masseter muscles of rats after occlusal interference.

METHODS

Fifty male Sprague-Dawley rats were randomly assigned into experimental group (n=40) and control group (n=10). In experimental group, 0.4 mm thick metal crown was cemented to the upper right first molar of the rat, and maintained for 3, 7, 10, 14 d separately (n=10 for each time point). No occlusal interference was applied for control group. Bilateral masseter muscles of all the rats were acquired under general anesthesia. The samples of 5 rats in each group were fully homogenized with 0.4 mol/L perchlorate (10 mL/g). The homogenates were centrifuged, filtered and analyzed for ATP, ADP, IMP, phosphocreatine, creatine and lactate content by high performance liquid chromatography. The other samples in each group were mixed with homogenates containing 5 mmol/L sodium iodoacetate (10 mL/g), then homogenized and measured for pH value by pH meter in thermostatic water bathunder 37 degrees centigrade.

RESULTS

Compared with control group, ATP content in bilateral masseter of the rats increased 3 d after occlusal interference [right side:(5.36±0.13) μmol/g,left side:(5.77±0.25) μmol/g] (P<0.05), and back to normal on 7, 10 and 14 d. There was an increase in IMP [right side:(0.21±0.03) μmol/g,left side:(0.19±0.03) μmol/g]and creatine content [right side:(24.76±2.94) μmol/g,left side:(27.75±2.23) μmol/g]in bilateral masseter of the rats 7 d after occlusal interference (P<0.05) and no difference was detected on 3, 10, and 14. Phosphocreatine content in bilateral masseter started to decline 7 d after occlusal interference and maintained the low level on 10 and 14 d [right side:(10.70±0.71) μmol/g, (11.57±0.52) μmol/g, (10.74±1.39) μmol/g, left side:(10.05±0.57) μmol/g, (10.75±1.12)μmol/g, (10.61±1.15) μmol/g](P<0.05). No change of ADP, lactate or pH level in bilateral muscles of the rats after occlusal interference was observed (P>0.05).

CONCLUSION

Occlusal interference influences the content of energy metabolites in masticatory muscle of rats, which may be related to the pathological process of masticatory muscles induced by occlusal interference, such as muscle pain, dysfunction and altered fiber architecture.

Nuclear envelope structural proteins facilitate nuclear shape changes accompanying embryonic differentiation and fidelity of gene expression

BACKGROUND

Nuclear size and shape are specific to a cell type, function, and location, and can serve as indicators of disease and development. We previously found that lamin A/C and associated nuclear envelope structural proteins were upregulated when murine embryonic stem (ES) cells differentiated to primitive endoderm cells. Here we further investigated the morphological changes of nuclei that accompany this differentiation.

RESULTS

The nuclei of undifferentiated wild type cells were found shaped as flattened, irregular ovals, whereas nuclei of Gata4-positive endoderm cells were more spherical, less flattened, and with a slightly reduced volume. The morphological change was confirmed in the trophectoderm and primitive endoderm lineages of E4.5 blastocysts, compared to larger and more irregularly shaped of the nuclei of the inner cell mass. We established ES cells genetically null for the nuclear lamina proteins lamin A/C or the inner nuclear envelope protein emerin, or compound mutant for both lamin A/C and emerin. ES cells deficient in lamin A/C differentiated to endoderm but less efficiently, and the nuclei remained flattened and failed to condense. The size and shape of emerin-deficient nuclei also remained uncondensed after treatment with RA. The emerin/lamin A/C double knockout ES cells failed to differentiate to endoderm cells, though the nuclei condensed but retained a generally flattened ellipsoid shape. Additionally, ES cells deficient for lamin A/C and/or emerin had compromised ability to undergo endoderm differentiation, where the differentiating cells often exhibited coexpression of pluripotent and differentiation markers, such as Oct3/4 and Gata4, respectively, indicating an infidelity of gene regulation.

CONCLUSIONS

The results suggest that changes in nuclear size and shape, which are mediated by nuclear envelope structural proteins lamin A/C and/or emerin, also impact gene regulation and lineage differentiation in early embryos. Nevertheless, mice lacking both lamin A/C and emerin were born at the expected frequency, indicating their embryonic development is completed despite the observed protein deficiency.

Endocytosis and Physiology: Insights from Disabled-2 Deficient Mice

Disabled-2 (Dab2) is a clathrin and cargo binding endocytic adaptor protein, and cell biology studies revealed that Dab2 plays a role in cellular trafficking of a number of transmembrane receptors and signaling proteins. A PTB/PID domain located in the N-terminus of Dab2 binds the NPXY motif(s) present at the cytoplasmic tails of certain transmembrane proteins/receptors. The membrane receptors reported to bind directly to Dab2 include LDL receptor and its family members LRP1 and LRP2 (megalin), growth factor receptors EGFR and FGFR, and the cell adhesion receptor beta1 integrin. Dab2 also serves as an adaptor in signaling pathways. Particularly, Dab2 facilitates the endocytosis of the Ras activating Grb2/Sos1 signaling complex, controls its disassembly, and thereby regulates the Ras/MAPK signaling pathway. Cellular analyses have suggested several diverse functions for the widely expressed proteins, and Dab2 is also considered a tumor suppressor, as loss or reduced expression is found in several cancer types. Dab2 null mutant mice were generated and investigated to determine if the findings from cellular studies might be important and relevant in intact animals. Dab2 conditional knockout mice mediated through a Sox2-Cre transgene have no obvious developmental defects and have a normal life span despite that the Dab2 protein is essentially absent in the mutant mice. The conditional knockout mice were grossly normal, though more recent investigation of the Dab2-deficient mice revealed several phenotypes, which can be accounted for by several previously suggested mechanisms. The studies of mutant mice established that Dab2 plays multiple physiological roles through its endocytic functions and modulation of signal pathways.

[Chinese multicenter randomized trial of customized chemotherapy based on BRCA1 (breast cancer susceptibility gene 1)-RAP80 (receptor-associated protein 80) mRNA expression in advanced non-small cell lung cancer (NSCLC) patients]

Objective: BRCA1 (breast cancer susceptibility gene 1) and RAP80 (receptor-associated protein 80) play key roles in predicting chemosensitivity of platinum and taxanes. A randomized trial was carried out to compare non-selected cisplatin-based chemotherapy with therapy customized according to BRCA1 and RAP80 expression. Methods: Advanced stage NSCLC patients whose tumor specimen was sufficient for molecular analysis were randomized (1∶3) to the control or experimental arm. Patients in the control arm received docetaxel/cisplatin; in the experimental arm, patients with low RAP80 expression received gemcitabine/cisplatin (Arm 1), those with intermediate/high RAP80 expression and low/intermediate BRCA1expression received docetaxel/cisplatin (Arm 2), and those with intermediate/high RAP80 expression and high BRCA1 expression received docetaxel alone (Arm 3). The primary end point was progression-free survival (PFS). Results: 226 patients were screened and 124 were randomized in this trial. ORR in the four subgroups was 22.6%, 48.4%, 30.3% and 19.2%, respectively (P=0.08); PFS was 4.74, 5.59, 3.78 and 2.73 months, respectively (P=0.55); and OS was 10.82, 14.44, 10.86 and 10.86 months, respectively (P=0.84). The common adverse effects included neutropenia, nausea, anemia and fatigue. Conclusions: No statistically significant difference of ORR, PFS or OS is observed in the experimental arms compared with the control arm. Patients with low RAP80 mRNA levels have a trend of better survival and higher response rate to gemcitabine/cisplatin chemotherapy.

Nuclear envelope structural defect underlies the main cause of aneuploidy in ovarian carcinogenesis

BACKGROUND

The Cancer Atlas project has shown that p53 is the only commonly (96 %) mutated gene found in high-grade serous epithelial ovarian cancer, the major histological subtype. Another general genetic change is extensive aneuploidy caused by chromosomal numerical instability, which is thought to promote malignant transformation. Conventionally, aneuploidy is thought to be the result of mitotic errors and chromosomal nondisjunction during mitosis. Previously, we found that ovarian cancer cells often lost or reduced nuclear lamina proteins lamin A/C, and suppression of lamin A/C in cultured ovarian epithelial cells leads to aneuploidy. Following up, we investigated the mechanisms of lamin A/C-suppression in promoting aneuploidy and synergy with p53 inactivation.

RESULTS

We found that suppression of lamin A/C by siRNA in human ovarian surface epithelial cells led to frequent nuclear protrusions and formation of micronuclei. Lamin A/C-suppressed cells also often underwent mitotic failure and furrow regression to form tetraploid cells, which frequently underwent aberrant multiple polar mitosis to form aneuploid cells. In ovarian surface epithelial cells isolated from p53 null mice, transient suppression of lamin A/C produced massive aneuploidy with complex karyotypes, and the cells formed malignant tumors when implanted in mice.

CONCLUSIONS

Based on the results, we conclude that a nuclear envelope structural defect, such as the loss or reduction of lamin A/C proteins, leads to aneuploidy by both the formation of tetraploid intermediates following mitotic failure, and the reduction of chromosome (s) following nuclear budding and subsequent loss of micronuclei. We suggest that the nuclear envelope defect, rather than chromosomal unequal distribution during cytokinesis, is the main cause of aneuploidy in ovarian cancer development.

Follicle Depletion Provides a Permissive Environment for Ovarian Carcinogenesis

We modeled the etiology of postmenopausal biology on ovarian cancer risk using germ cell-deficient white-spotting variant (Wv) mice, incorporating oncogenic mutations. Ovarian cancer incidence is highest in peri- and postmenopausal women, and epidemiological studies have established the impact of reproductive factors on ovarian cancer risk. Menopause as a result of ovarian follicle depletion is thought to contribute to higher cancer risk. As a consequence of follicle depletion, female Wv mice develop ovarian tubular adenomas, a benign epithelial tumor corresponding to surface epithelial invaginations and papillomatosis frequently found in postmenopausal human ovaries. Lineage tracing using MISR2-Cre indicated that the tubular adenomas that developed in Wv mice were largely derived from the MISR2 lineage, which marked only a fraction of ovarian surface and oviduct epithelial cells in wild-type tissues. Deletion of p27, either heterozygous or homozygous, was able to convert the benign tubular adenomas into more proliferative tumors. Restricted deletion of p53 in Wv/Wv mice by either intrabursal injection of adenoviral Cre or inclusion of the MISR2-Cre transgene also resulted in augmented tumor growth. This finding suggests that follicle depletion provides a permissive ovarian environment for oncogenic transformation of epithelial cells, presenting a mechanism for the increased ovarian cancer risk in postmenopausal women.

[A prospective study on the effects of levonorgestrel-releasing intrauterine system for adenomyosis with menorrhagia]

OBJECTIVE

To investigate treatment effects of levonorgestrel-releasing intrauterine system (LNG-IUS) for adenomyosis with menorrhea in a prospective study.

METHODS

From December 2006 to December 2014, patients of symptomatic adenomyosis diagnosed by transvaginal ultrasound in outpatient or inpatient clinics of Peking Union Medical College Hospital were given the treatment of LNG-IUS. Before and after placement of LNG-IUS, all the patients' parameters were recorded prospectively, including scores of menstruation blood loss, carrying status of IUS, symptoms and scores of dysmenorrhea, biochemical indicators, physical parameters, menstruation patterns and adverse effects. Changes of pictorial chart scores of menstruation and distribution of anemia during follow-up were analyzed.

RESULTS

Totally 1 100 women meets inclusion criteria, among which 618 cases (56.18%, 618/1 100) had severe menorrhea, with median follow-up period of 28 months (range 1- 60 months), and accumulative carrying rate of 66% at 60 months follow-up. After placement of LNG-IUS, compared with baselines, pictorial chart scores and ratio of menorrhea had decreased significantly (all P<0.01), the scroes of menstruation were 157±34, 94±35, 70±33, 67±18, 67±20, 65±19, 66±19, 65±21 at 0, 3, 6, 12, 24, 36, 48 and 60 months respectively. During 24 months after placement of LNG-IUS, pictorial chart scores and distribution of anemia had improved significantly compared with preceding period (all P<0.01). We found no dependent factors predicting improvement of pictorial chart scores of menorrhea, which was neither relevant with simultaneous changes of menstruation patterns nor adverse effects (all P>0.05).

CONCLUSIONS

LNG-IUS is effective for adenomyosis of menorrhea. Improvement of menstruation blood loss is independent on patients characters, menstruation patterns or adverse effects.

[A prospective cohort study on effects of levonorgestrel-releasing intrauterine system for adenomyosis with severe dysmenorrhea]

OBJECTIVE

To investigate treatment effects of levonorgestrel-releasing intrauterine system (LNG-IUS) for adenomyosis with severe dysmenorrhea in a prospective cohort study.

METHODS

From December 2006 to December 2014, patients of symptomatic adenomyosis diagnosed by transvaginal ultrasound in outpatient or inpatient clinics of Peking Union Medical College Hospital were given the treatment of LNG-IUS. Before and after placement of LNG-IUS, all the patients' parameters were recorded prospectively, including symptoms and scores of dysmenorrhea, menstruation scores, biochemical indicators, physical parameters, carrying status of LNG-IUS, menstruation patterns and adverse effects. Changes of scores and patterns of pain during follow-up were analyzed.

RESULTS

Totally 1 100 women meets inclusion criteria, among which 640 cases (58.18%, 640/1 100) had severe dysmeorrhea, with median follow-up period of 35 months (range 1-60 months), and accumulative carrying rate of 65% at 60 months follow-up. After placement of LNG-IUS, scores of pain and ratio of severe dysmenorrhea had decreased significantly compared with baselines (all P<0.01), the scroes of visual analog scale (VAS) were 8.1±0.9, 5.5±2.4, 4.6±2.4, 3.3±2.2, 2.2±2.1, 2.2±1.8, 1.4±1.6 and 1.3±1.3 at 0, 3, 6, 12, 24, 36, 48 and 60 months respectively. During 36 months after placement of LNG-IUS, scores of pain had improved significantly compared with preceding period (all P<0.01). We found no universal dependent factors predicting improvement of pain, which was neither relevant with simultaneous changes of menstruation patterns nor adverse effects (all P>0.05).

CONCLUSION

LNG-IUS is effective for adenomyosis of severe dysmenorrhea. Improvement of pain is independent on patients characters, menstruation patterns or adverse effects.

Endocytic adaptors Arh and Dab2 control homeostasis of circulatory cholesterol

High serum cholesterol (hypercholesterolemia) strongly associates with cardiovascular diseases as the atherogenic LDLs promote atheroma development in arteries (atherosclerosis). LDL clearance from the circulation by LDL receptor (LDLR)-mediated endocytosis by hepatic and peripheral tissues and subsequent feedback regulation of endogenous synthesis of cholesterol is a key determinant of serum LDL level. Human mutation analysis revealed that autosomal recessive hypercholesterolemia (ARH), an LDLR endocytic adaptor, perturbs LDLR function and thus impacts serum cholesterol levels. In our genetic analysis of mutant mice, we found that deletion of another LDLR endocytic adaptor, Disabled-2 (Dab2), only slightly affected serum cholesterol levels. However, elimination of both arh and dab2 genes in mice resulted in profound hypercholesterolemia similar to that resulting from ldlr homozygous deletion. In the liver, Dab2 is expressed in sinusoid endothelial cells but not in hepatocytes. When deleting both Dab2 and Arh, HMG-CoA reductase level increased to the level similar to that of ldlr knockout. Thus, in the absence of Arh, Dab2 in liver endothelial cells regulates cholesterol synthesis in hepatocytes. We conclude that the combination of Arh and Dab2 is responsible for the majority of adaptor function in LDLR endocytosis and LDLR-mediated cholesterol homeostasis.

Lamin A/C deficiency is an independent risk factor for cervical cancer

BACKGROUND

In the past, cervical cancer has been linked to Human Papilloma Virus (HPV) infection. Previously, we found that pre-neoplastic breast and ovarian lesions may be associated with lamin A/C deficiency, resulting in abnormal nuclear morphologies and chromosomal instability. Ultimately, these phenomena are thought to lead to cancer. Here, we assessed lamin A/C deficiency as an indicator for the risk to develop cervical cancer.

METHODS

The expression of lamin A/C was assessed by Western blotting in cervical uterine smears (CUS) of 76 adult women from Benin concomitant with nuclear morphology assessment and HPV genotyping using microscopy and PCR-based assays, respectively. In vitro analyses were performed to uncover the mechanism underlying lamin A/C expression alterations observed in vivo. The presence of cervical intra-epithelial neoplasia (CIN) was assessed by colposcopy.

RESULTS

Normal lamin A/C expression (group A) was observed in 39% of the CUS, weak lamin A/C expression (group B) was observed in 28% of the CUS and no lamin A/C expression (group C) was observed in 33% of the CUS tested. Infection with oncogenic HPV was found to be significantly higher in group C (36%) than in groups A (17%) and B (14%). Two years after our first assessment, CIN was observed in 20% of the women in group C. The in vitro application of either a histone deacetylase inhibitor (trichostatin) or a protein kinase inhibitor (staurosporine) was found to restore lamin A/C expression in cervical cancer-derived cells.

CONCLUSION

Lamin A/C deficiency may serve as an independent risk factor for CIN development and as an indicator for preventive therapy in cervical cancer.

Association of novel polymorphisms of forkhead box L2 and growth differentiation factor-9 genes with egg production traits in local Chinese Dagu hens

Transcription factor forkhead box L2 (FOXL2) and growth differentiation factor-9 (GDF9) genes have critical roles in the regulation of hen ovarian development. In the present study, these genes were explored as possible molecular markers associated with BW, hen-housed egg production, and egg weight in Chinese Dagu hens. Samples were analyzed using the PCR-single strand conformation polymorphism (PCR-SSCP) technique followed by sequencing analysis, and two novel single nucleotide polymorphisms (SNPs) were identified within these candidate genes. Among them, an A/G transition at base position 238 in the coding region of the FOXL2 gene and a G/T transversion at base position 1609 in exon 2 of the GDF9 gene were found to be polymorphic and named SNPs A238G and G1609T, respectively. The SNP A238G (FOXL2) leads to a nonsynonymous substitution (isoleucine77-to-valine), and when the 360 Dagu hen samples were divided into genotypes AA and AB, allele A was found to be present at a higher frequency. Furthermore, the AA genotype correlated with significantly higher hen-housed egg production at 30, 43, 57, and 66 wk of age and with a higher egg weight at 43 wk (P<0.05). For the SNP G1609T (GDF9), the hens were typed into TT and TC genotypes, with the T allele shown to be dominant. The TC genotype was also markedly correlated with higher hen-housed egg production and a higher egg weight (P<0.05). Moreover, four haplotypes were reconstructed based on these two SNPs, with the AATC haplotype found to be correlated with the highest hen-housed egg production at 30 to 66 wk of age and with higher egg weights at 43 wk (P<0.05). Collectively, the two SNPs identified in this study might be used as possible genetic molecular markers to aid in the improvement of egg production traits in chicken breeding.

Global deletion of Trp53 reverts ovarian tumor phenotype of the germ cell-deficient white spotting variant (Wv) mice

White spotting variant (Wv) mice are spontaneous mutants attributed to a point mutation in the c-Kit gene, which reduces the tyrosine kinase activity to around 1% and affects the development of melanocytes, mast cells, and germ cells. Homozygous mutant mice are sterile but can live nearly a normal life span. The female Wv mice have a greatly reduced ovarian germ cell and follicle reserve at birth, and the remaining follicles are largely depleted soon after the females reach reproductive stage at around 7 weeks of age. Consequently, ovarian epithelial tumors develop in 100% of Wv females by 3 to 4 months of age. These tumors, called tubular adenomas, are benign but can become invasive in older Wv mice.

We tested if additional genetic mutation(s) could convert the benign ovarian epithelial tumors to malignant tumors by crossing the Wv mutant into the Trp53 knockout background. Surprisingly, we found that global deletion of Trp53 suppressed the development of ovarian tubular adenomas in Wv mice. The ovaries of Wv/Wv; Trp53 (−/−) mice were covered by a single layer of surface epithelium and lacked excessive epithelial proliferation. Rather, the ovaries contained a small number of follicles. The presence of ovarian follicles and granulosa cells, as indicated by Pgc7 and inhibin-alpha expression, correlated with the absence of epithelial lesions. A reduction of Pten gene dosage, as in Wv/Wv; Pten (+/−) mice, produced a similar, though less dramatic, phenotype. We conclude that deletion of Trp53 prolongs the survival of ovarian follicles in Wv mice and consequently prevents the proliferation of ovarian epithelial cells and development of ovarian tubular adenomas. The results suggest that various cell types within the ovary communicate and mutually modulate, and an intact tissue environment is required to ensure homeostasis of ovarian surface epithelial cells. Especially, the current finding emphasizes the importance of ovarian follicles in suppressing the hyperplastic growth of ovarian epithelial cells, dominating over the loss of p53.

New insights into implication of the SLIT/ROBO pathway in the prehierarchical follicle development of hen ovary

The SLIT/Roundabout (ROBO) pathway is involved in follicle development of mammalian ovary, and 2 secreted hormones activin A and inhibin A have potential roles in modulation of the SLIT/ROBO system, but the related actions remain poorly understood in bird. The aims of the present study were to examine the spatial and temporal expression of the SLIT ligand genes (SLIT1, SLIT2, and SLIT3) and their receptor ROBO1, ROBO2, ROBO3, and ROBO4 genes in various-sized prehierarchical follicles during hen ovary development and the effects of activin A and inhibin A on the expression of these genes in the cultured hen follicles. Our result demonstrated that the transcripts of the 3 SLIT genes were highly expressed in the developing follicles and expression patterns of the SLIT transcripts were different from those of ROBO genes detected by real-time quantitative reverse transcriptase PCR. Both SLIT and ROBO transcripts were predominantly expressed in oocytes and granulosa cells from the prehierarchichal follicles examined by in situ hybridization. The localization for SLIT and ROBO proteins was revealed by immunohistochemistry similar to the spatial distribution of their transcript. In cultured follicles (4 to 8 mm in diameter), the expression levels of SLIT and ROBO members are hormonally regulated by activin A (10 ng/mL) and/or inhibin A (20 ng/mL) after treatment for 24 h. However, the expression of only SLIT2, SLIT3, and ROBO3 mRNA presented a directly opposite response to activin A and inhibin A hormones. These results indicate that SLIT/ROBO pathway is implicated in the prehierarchical follicular development of the hen ovary by an intrafollicular autocrine and/or paracrine action, and is influenced by activin A and inhibin A hormones.

Role of TRPV1 and ASIC3 channels in experimental occlusal interference-induced hyperalgesia in rat masseter muscle

BACKGROUND

Masticatory muscle pain may occur following immediate occlusal alteration by dental treatment. The underlying mechanisms are poorly understood. Transient receptor potential vanilloid-1 (TRPV1) and acid-sensing ion channel-3 (ASIC3) mediate muscle hyperalgesia under various pathologic conditions. We have developed a rat model of experimental occlusal interference (EOI) that consistently induces mechanical hyperalgesia in jaw muscles. Whether TRPV1 and ASIC3 mediate this EOI-induced hyperalgesia is unknown.

METHODS

Rat model of EOI-induced masseter hyperalgesia was established. Real-time polymerase chain reaction, Western blot and retrograde labelling combined with immunofluorescence were performed to evaluate the modulation of TRPV1 and ASIC3 expression in trigeminal ganglia (TGs) and masseter afferents of rats after EOI. The effects of intramuscular administration of TRPV1 and ASIC3 antagonists on the EOI-induced hyperalgesia in masseter muscle were examined.

RESULTS

After EOI, gene expressions and protein levels of TRPV1 and ASIC3 in bilateral TGs were up-regulated. The percentage of ASIC3- (but not TRPV1-) positive neurons in masseter afferents increased after EOI. More small-sized and small to medium-sized masseter afferents expressed TRPV1 and ASIC3 separately following EOI. These changes peaked at day 7 and then returned to original status within 10 days after EOI. Intramuscular administration of the TRPV1 antagonist AMG-9810 partially reversed this mechanical hyperalgesia in masseter muscle. No improvement was exhibited after administration of the ASIC3 antagonist APETx2. Co-injection of AMG-9810 and APETx2 enhanced the effect of AMG-9810 administration alone.

CONCLUSIONS

Peripheral TRPV1 and ASIC3 contribute to the development of the EOI-induced mechanical hyperalgesia in masseter muscle.

Usefulness of normal saline for sealing the needle track after CT-guided lung biopsy

AIM

To determine whether the use of normal saline for sealing the needle track can reduce the incidence of pneumothorax and chest tube placement after computed tomography (CT)-guided lung biopsy.

MATERIALS AND METHODS

A prospective, randomised, controlled trial enrolling 322 patients was conducted. All patients were randomly assigned to one of two groups: those in whom the needle track was not sealed with normal saline (n=161, Group A) and those who did receive normal saline (n=161, Group B). CT-guided biopsy was performed with coaxial technique. Normal saline, which ranged from 1-3 ml, was injected while the trocar needle was being withdrawn. Patient characteristics, lesion, and procedure variables were analysed as potential risk variables for occurrence of pneumothorax and chest tube placement.

RESULTS

The incidence of pneumothorax was 26.1% in Group A and 6.2% in Group B (p<0.001). Nine patients in Group A and one patient in Group B required chest tube placement (p=0.010). Using multiple logistic regression analysis, smaller lesion size, greater needle-pleural angle, longer lesion-pleural distance, presence of emphysema, and no sealing the needle track with normal saline were significantly associated with an increased risk of pneumothorax, and that the latter three factors were also associated with an increased risk of pneumothorax requiring chest tube placement.

CONLUSION

Normal saline for sealing the needle track significantly reduces the incidence of pneumothorax and prevents subsequent chest tube placement after CT-guided lung biopsy.

Development of a mouse model of menopausal ovarian cancer

Despite significant understanding of the genetic mutations involved in ovarian epithelial cancer and advances in genomic approaches for expression and mutation profiling of tumor tissues, several key questions in ovarian cancer biology remain enigmatic: the mechanism for the well-established impact of reproductive factors on ovarian cancer risk remains obscure; cell of origin of ovarian cancer continue to be debated; and the precursor lesion, sequence, or events in progression remain to be defined. Suitable mouse models should complement the analysis of human tumor tissues and may provide clues to these questions currently perplexing ovarian cancer biology. A potentially useful model is the germ cell-deficient Wv (white spotting variant) mutant mouse line, which may be used to study the impact of menopausal physiology on the increased risk of ovarian cancer. The Wv mice harbor a point mutation in c-Kit that reduces the receptor tyrosine kinase activity to about 1–5% (it is not a null mutation). Homozygous Wv mutant females have a reduced ovarian germ cell reservoir at birth and the follicles are rapidly depleted upon reaching reproductive maturity, but other biological phenotypes are minimal and the mice have a normal life span. The loss of ovarian function precipitates changes in hormonal and metabolic activity that model features of menopause in humans. As a consequence of follicle depletion, the Wv ovaries develop ovarian tubular adenomas, a benign epithelial tumor corresponding to surface epithelial invaginations and papillomatosis that mark human ovarian aging. Ongoing work will test the possibility of converting the benign epithelial tubular adenomas into neoplastic tumors by addition of an oncogenic mutation, such as of Tp53, to model the genotype and biology of serous ovarian cancer. Model based on the Wv mice may have the potential to gain biological and etiological insights into ovarian cancer development and prevention.

Cell adhesion and sorting in embryoid bodies derived from N- or E-cadherin deficient murine embryonic stem cells

The primitive endoderm epithelial structure in mouse blastocysts forms following cell differentiation and subsequent sorting, and this two-step process can be reproduced in vitro using an embryoid body model. We found that in the chimeric embryoid bodies consisting of paired wildtype and E-cadherin null ES cells, the wildtype sorted to the center and were enveloped by the less adhesive E-cadherin null cells, in accord with Steinberg's hypothesis. However, wildtype and N-cadherin null ES cells intermixed and did not segregate, a situation that may be explained by Albert Harris' modified principle, which incorporates the unique properties of living cells. Furthermore, in chimeric embryoid bodies composed of N-cadherin and E-cadherin null ES cells, the two weakly interacting cell types segregated but did not envelop one another. Lastly, the most consistent and striking observation was that differentiated cells sorted to the surface and formed an enveloping layer, regardless of the relative cell adhesive affinity of any cell combination, supporting the hypothesis that the ability of the differentiated cells to establish apical polarity is the determining factor in surface sorting and positioning.