Safety of Ancestral Monovalent BNT162b2, mRNA-1273, and NVX-CoV2373 COVID-19 Vaccines in US Children Aged 6 Months to 17 Years

Importance

Active monitoring of health outcomes after COVID-19 vaccination provides early detection of rare outcomes that may not be identified in prelicensure trials.

Objective

To conduct near-real-time monitoring of health outcomes after COVID-19 vaccination in the US pediatric population.

Design, Setting, and Participants

This cohort study evaluated 21 prespecified health outcomes after exposure before early 2023 to BNT162b2, mRNA-1273, or NVX-CoV2373 ancestral monovalent COVID-19 vaccines in children aged 6 months to 17 years by applying a near-real-time monitoring framework using health care data from 3 commercial claims databases in the US (Optum [through April 2023], Carelon Research [through March 2023], and CVS Health [through February 2023]). Increased rates of each outcome after vaccination were compared with annual historical rates from January 1 to December 31, 2019, and January 1 to December 31, 2020, as well as between April 1 and December 31, 2020.

Exposure

Receipt of an ancestral monovalent BNT162b2, mRNA-1273, or NVX-CoV2373 COVID-19 vaccine dose identified through administrative claims data linked with Immunization Information Systems data.

Main Outcomes and Measures

Twenty-one prespecified health outcomes, of which 15 underwent sequential testing and 6 were only monitored descriptively due to lack of historical rates.

Results

Among 4 102 016 vaccinated enrollees aged 6 months to 17 years, 2 058 142 (50.2%) were male and 3 901 370 (95.1%) lived in an urban area. Thirteen of 15 sequentially tested outcomes did not meet the threshold for a statistical signal. Statistical signals were detected for myocarditis or pericarditis after BNT162b2 vaccination in children aged 12 to 17 years and seizure after vaccination with BNT162b2 and mRNA-1273 in children aged 2 to 4 or 5 years. However, in post hoc sensitivity analyses, a statistical signal for seizure was observed only after mRNA-1273 when 2019 background rates were selected; no statistical signal was observed when 2022 rates were selected.

Conclusions and Relevance

In this cohort study of pediatric enrollees across 3 commercial health insurance databases, statistical signals detected for myocarditis or pericarditis after BNT162b2 (ages 12-17 years) were consistent with previous reports, and seizures after BNT162b2 (ages 2-4 years) and mRNA-1273 vaccinations (ages 2-5 years) should be further investigated in a robust epidemiologic study with confounding adjustment. The US Food and Drug Administration concludes that the known and potential benefits of COVID-19 vaccination outweigh the known and potential risks of COVID-19 infection.

Severe Hypocalcemia With Denosumab Among Older Female Dialysis-Dependent Patients

Importance

Dialysis-dependent patients experience high rates of morbidity from fractures, yet little evidence is available on optimal treatment strategies. Chronic kidney disease-mineral and bone disorder is nearly universal in dialysis-dependent patients, complicating diagnosis and treatment of skeletal fragility.

Objective

To examine the incidence and comparative risk of severe hypocalcemia with denosumab compared with oral bisphosphonates among dialysis-dependent patients treated for osteoporosis.

Design, Setting, and Participants

Retrospective cohort study of female dialysis-dependent Medicare patients aged 65 years or older who initiated treatment with denosumab or oral bisphosphonates from 2013 to 2020. Clinical performance measures including monthly serum calcium were obtained through linkage to the Consolidated Renal Operations in a Web-Enabled Network database.

Exposures

Denosumab, 60 mg, or oral bisphosphonates.

Main Outcomes and Measures

Severe hypocalcemia was defined as total albumin-corrected serum calcium below 7.5 mg/dL (1.88 mmol/L) or a primary hospital or emergency department hypocalcemia diagnosis (emergent care). Very severe hypocalcemia (serum calcium below 6.5 mg/dL [1.63 mmol/L] or emergent care) was also assessed. Inverse probability of treatment-weighted cumulative incidence, weighted risk differences, and weighted risk ratios were calculated during the first 12 treatment weeks.

Results

In the unweighted cohorts, 607 of 1523 denosumab-treated patients and 23 of 1281 oral bisphosphonate-treated patients developed severe hypocalcemia. The 12-week weighted cumulative incidence of severe hypocalcemia was 41.1% with denosumab vs 2.0% with oral bisphosphonates (weighted risk difference, 39.1% [95% CI, 36.3%-41.9%]; weighted risk ratio, 20.7 [95% CI, 13.2-41.2]). The 12-week weighted cumulative incidence of very severe hypocalcemia was also increased with denosumab (10.9%) vs oral bisphosphonates (0.4%) (weighted risk difference, 10.5% [95% CI, 8.8%-12.0%]; weighted risk ratio, 26.4 [95% CI, 9.7-449.5]).

Conclusions and Relevance

Denosumab was associated with a markedly higher incidence of severe and very severe hypocalcemia in female dialysis-dependent patients aged 65 years or older compared with oral bisphosphonates. Given the complexity of diagnosing the underlying bone pathophysiology in dialysis-dependent patients, the high risk posed by denosumab in this population, and the complex strategies required to monitor and treat severe hypocalcemia, denosumab should be administered after careful patient selection and with plans for frequent monitoring.

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.

Risk of Severe COVID-19 in Prevalent Users of Alpha-1 Adrenergic Receptor Antagonists: A National Case-Control Study of Medicare Beneficiaries

BACKGROUND

Alpha-1 adrenergic receptor antagonists prevent cytokine storm in mouse sepsis models. This led to the hypothesis that alpha-1 blockers may prevent severe coronavirus disease 2019 (COVID-19), which is characterized by hypercytokinemia and progressive respiratory failure.

METHODS

We performed an observational case-control study in male Medicare beneficiaries aged 65 years or older, with or without benign prostatic hyperplasia (BPH), and treated with alpha-1 receptor blockers or 5-alpha reductase inhibitors. Adjusted odds ratios (aOR) and 95% confidence intervals (CI) were estimated for outcomes of uncomplicated and severe COVID-19 hospitalization (intensive care unit admission, invasive mechanical ventilation, or death).

RESULTS

There were 20,963 cases of hospitalized COVID-19 matched to 101,161 controls on calendar date and neighborhood of residence. In the primary analysis (males with BPH), there was no difference in risk of uncomplicated COVID-19 hospitalization (aOR 1.08, 95% CI 0.996-1.17) or hospitalization with severe complications (aOR 0.97, 95% CI 0.88-1.08). In the secondary analysis (males with or without BPH), the corresponding aORs were 1.02 (95% CI, 0.96-1.09) (uncomplicated) and 0.99 (95% CI, 0.91-1.07) (complicated), respectively. Subgroup and sensitivity analyses yielded similar results. Of note, there was no difference in risk of severe COVID-19 hospitalization when comparing non-selective vs selective alpha-1 blocker use (aOR 0.98, 95% CI 0.86-1.10), higher- vs lower-dose alpha-1 blocker use (aOR 0.96, 95% CI 0.86-1.08), or current vs remote alpha-1 blocker use (aOR 1.04, 95% CI 0.91-1.18).

CONCLUSIONS

Prevalent use of alpha-1 receptor blockers was not associated with a protective or harmful effect on risk of uncomplicated or severe hospitalized COVID-19.

Safety of the BNT162b2 COVID-19 Vaccine in Children Aged 5 to 17 Years

Importance

Active monitoring of health outcomes after COVID-19 vaccination offers early detection of rare outcomes that may not be identified in prelicensure trials.

Objective

To conduct near-real-time monitoring of health outcomes following BNT162b2 COVID-19 vaccination in the US pediatric population aged 5 to 17 years.

Design, Setting, and Participants

This population-based study was conducted under a public health surveillance mandate from the US Food and Drug Administration. Participants aged 5 to 17 years were included if they received BNT162b2 COVID-19 vaccination through mid 2022 and had continuous enrollment in a medical health insurance plan from the start of an outcome-specific clean window until the COVID-19 vaccination. Surveillance of 20 prespecified health outcomes was conducted in near real time within a cohort of vaccinated individuals from the earliest Emergency Use Authorization date for the BNT162b2 vaccination (December 11, 2020) and was expanded as more pediatric age groups received authorization through May and June 2022. All 20 health outcomes were monitored descriptively, 13 of which additionally underwent sequential testing. For these 13 health outcomes, the increased risk of each outcome after vaccination was compared with a historical baseline with adjustments for repeated looks at the data as well as a claims processing delay. A sequential testing approach was used, which declared a safety signal when the log likelihood ratio comparing the observed rate ratio against the null hypothesis exceeded a critical value.

Exposure

Exposure was defined as receipt of a BNT162b2 COVID-19 vaccine dose. The primary analysis assessed primary series doses together (dose 1 + dose 2), and dose-specific secondary analyses were conducted. Follow-up time was censored for death, disenrollment, end of the outcome-specific risk window, end of the study period, or a receipt of a subsequent vaccine dose.

Main Outcomes

Twenty prespecified health outcomes: 13 were assessed using sequential testing and 7 were monitored descriptively because of a lack of historical comparator data.

Results

This study included 3 017 352 enrollees aged 5 to 17 years. Of the enrollees across all 3 databases, 1 510 817 (50.1%) were males, 1 506 499 (49.9%) were females, and 2 867 436 (95.0%) lived in an urban area. In the primary sequential analyses, a safety signal was observed only for myocarditis or pericarditis after primary series vaccination with BNT162b2 in the age group 12 to 17 years across all 3 databases. No safety signals were observed for the 12 other outcomes assessed using sequential testing.

Conclusions and Relevance

Among 20 health outcomes that were monitored in near real time, a safety signal was identified for only myocarditis or pericarditis. Consistent with other published reports, these results provide additional evidence that COVID-19 vaccines are safe in children.

Non-equilibrium molecular simulations of thin film rupture

The retraction of thin films, as described by the Taylor-Culick (TC) theory, is subject to widespread debate, particularly for films at the nanoscale. We use non-equilibrium molecular dynamics simulations to explore the validity of the assumptions used in continuum models by tracking the evolution of holes in a film. By deriving a new mathematical form for the surface shape and considering a locally varying surface tension at the front of the retracting film, we reconcile the original theory with our simulation to recover a corrected TC speed valid at the nanoscale.

Listening to a popular upbeat song can lead to more adaptive cognitive inferences for stressful events in non-clinical adult populations

OBJECTIVE

We tested the effect of music on idiographic cognitive inferences about stressful events.

METHOD

In Study 1 (n = 336), adult participants from the United States were randomly assigned to non-familiar songs that differed by lyrical content and tempo. In Studies 2 (n = 302) and 3 (n = 323), adult participants from the United States were randomly assigned to either a positive, neutral or no-song condition.

RESULTS

The results of Study 1 failed to support any of the study hypotheses. Given the null results, we decided to conduct a second study focused on increasing external validity and power (i.e., including fewer experimental conditions). The results of Study 2 showed that adults randomly assigned to a familiar upbeat song condition experienced an increase in positive affect and a decrease in event-specific negative cognitions. A third study was then conducted to replicate the results and rule out a potential confound. Results of Study 3 corroborated the results of Study 2.

CONCLUSION

Taken together (Studies 2 and 3), results indicate it may be useful for future research to test the extent to which familiar upbeat music can be helpful during cognitive restructuring activities in psychotherapy to nudge people to generate more adaptive cognitions.

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.

Reduced hip bone mineral density is associated with high levels of calciprotein particles in patients with Fabry disease

Calciprotein particles (CPP) are nanoscale mineralo-protein aggregates that help stabilize excess mineral in the circulation. We examined the relationship between CPP and bone mineral density in Fabry disease patients. We found an inverse correlation with total hip and femoral neck density, but none with lumbar spine.

PURPOSE

Calciprotein particles (CPP) are colloidal mineral-protein complexes made up primarily of the circulating glycoprotein fetuin-A, calcium, and phosphate. They form in extracellular fluid and facilitate the stabilization, transport, and clearance of excess minerals from the circulation. While most are monomers, they also exist in larger primary (CPP-I) and secondary (CPP-II) form, both of which are reported to be raised in pathological states. This study sought to investigate CPP levels in the serum of patients with Fabry disease, an X-linked systemic lysosomal storage disorder that is associated with generalized inflammation and low bone mineral density (BMD).

METHODS

We compared serum CPP-I and CPP-II levels in 59 patients with Fabry disease (37 female) with levels in an age-matched healthy adult cohort (n=28) and evaluated their association with BMD and biochemical data obtained from routine clinical review.

RESULTS

CPP-I and CPP-II levels were higher in male Fabry disease patients than female sufferers as well as their corresponding sex- and age-matched controls. CPP-II levels were inversely correlated with BMD at the total hip and femoral neck, but not the lumbar spine. Regression analyses revealed that these associations were independent of common determinants of BMD, but at the femoral neck, a significant association was only found in female patients.

CONCLUSION

Low hip BMD was associated with high CPP-II in patients with Fabry disease, but further work is needed to investigate the relevance of sex-related differences and to establish whether CPP measurement may aid assessment of bone disease in this setting.

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.

Risk of Covid-19-Related Hospitalization and More Severe Outcomes in Medicare Beneficiaries Treated with Renin-Angiotensin-Aldosterone System Inhibitors for Hypertension

BACKGROUND

There are theoretical concerns that angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) could increase the risk of severe Covid-19.

OBJECTIVE

To determine if ACEIs and ARBs are associated with an increased risk of Covid-19 hospitalization overall, or hospitalization involving intensive care unit (ICU) admission, invasive mechanical ventilation, or death.

DESIGN

Observational case-control study.

PARTICIPANTS

Medicare beneficiaries aged ≥ 66 years with hypertension, treated with ACEIs, ARBs, calcium channel blockers (CCBs), or thiazide diuretics.

MAIN MEASURES

Adjusted odds ratios (OR) and 95% confidence intervals (CI) for the outcomes of Covid-19 hospitalization, or hospitalization involving ICU admission, invasive mechanical ventilation, or death.

RESULTS

A total of 35,300 cases of hospitalized Covid-19 were matched to 228,228 controls on calendar date and neighborhood of residence. The median age of cases was 79 years, 57.4% were female, and the median duration of hospitalization was 8 days (interquartile range 5-12). ACEIs and ARBs were associated with a slight reduction in Covid-19 hospitalization risk compared with treatment with other first-line antihypertensives (OR for ACEIs 0.95, 95% CI 0.92-0.98; OR for ARBs 0.94, 95% CI 0.90-0.97). Similar results were obtained for hospitalizations involving ICU admission, invasive mechanical ventilation, or death. There were no meaningful differences in risk for ACEIs compared with ARBs. In an analysis restricted to monotherapy with a first-line agent, CCBs were associated with a small increased risk of Covid-19 hospitalization compared with ACEIs (OR 1.09, 95% CI 1.04-1.14), ARBs (OR 1.10, 95% CI 1.05-1.15), or thiazide diuretics (OR 1.11, 95% CI 1.03-1.19).

CONCLUSIONS

ACEIs and ARBs were not associated with an increased risk of Covid-19 hospitalization or with hospitalization involving ICU admission, invasive mechanical ventilation, or death. The finding of a small increased risk of Covid-19 hospitalization with CCBs was unexpected and could be due to residual confounding.

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.

Viscuit and the fluctuation theorem investigation of shear viscosity by molecular dynamics simulations: The information and the noise

The shear viscosity, η, of model liquids and solids is investigated within the framework of the viscuit and Fluctuation Theorem (FT) probability distribution function (PDF) theories, following Heyes et al. [J. Chem. Phys. 152, 194504 (2020)] using equilibrium molecular dynamics (MD) simulations on Lennard-Jones and Weeks-Chandler-Andersen model systems. The viscosity can be obtained in equilibrium MD simulation from the first moment of the viscuit PDF, which is shown for finite simulation lengths to give a less noisy plateau region than the Green-Kubo method. Two other formulas for the shear viscosity in terms of the viscuit and PDF analysis are also derived. A separation of the time-dependent average negative and positive viscuits extrapolated from the noise dominated region to zero time provides another route to η. The third method involves the relative number of positive and negative viscuits and their PDF standard deviations on the two sides for an equilibrium system. For the FT and finite shear rates, accurate analytic expressions for the relative number of positive to negative block average shear stresses is derived assuming a shifted Gaussian PDF, which is shown to agree well with non-equilibrium molecular dynamics simulations. A similar treatment of the positive and negative block average contributions to the viscosity is also shown to match the simulation data very well.

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.

Recent Administration of Iodinated Contrast Renders Core Infarct Estimation Inaccurate Using RAPID Software

BACKGROUND AND PURPOSE

Automated CTP software is increasingly used for extended window emergent large-vessel occlusion to quantify core infarct. We aimed to assess whether RAPID software underestimates core infarct in patients with an extended window recently receiving IV iodinated contrast.

MATERIALS AND METHODS

We reviewed a prospective, single-center data base of 271 consecutive patients who underwent CTA ± CTP for acute ischemic stroke from May 2018 through January 2019. Patients with emergent large-vessel occlusion confirmed by CTA in the extended window (>6 hours since last known well) and CTP with RAPID postprocessing were included. Two blinded raters independently assessed CT ASPECTS on NCCT performed at the time of CTP. RAPID software used relative cerebral blood flow of <30% as a surrogate for irreversible core infarct. Patients were dichotomized on the basis of receiving recent IV iodinated contrast (<8 hours before CTP) for a separate imaging study.

RESULTS

The recent IV contrast and contrast-naïve cohorts comprised 23 and 15 patients, respectively. Multivariate linear regression analysis demonstrated that recent IV contrast administration was independently associated with a decrease in the RAPID core infarct estimate (proportional increase = 0.34; 95% CI, 0.12-0.96; P = .04).

CONCLUSIONS

Patients who received IV iodinated contrast in proximity (<8 hours) to CTA/CTP as part of a separate imaging study had a much higher likelihood of core infarct underestimation with RAPID compared with contrast-naïve patients. Over-reliance on RAPID postprocessing for treatment disposition of patients with extended window emergent large-vessel occlusion should be avoided, particularly with recent IV contrast administration.

Single trajectory transport coefficients and the energy landscape by molecular dynamics simulations

The Green-Kubo (GK) method is widely used to calculate the transport coefficients of model liquids by Molecular Dynamics (MD) simulation. A reformulation of GK was proposed by Heyes et al. [J. Chem. Phys. 150, 174504 (2019)], which expressed the shear viscosity in terms of a probability distribution function (PDF) of "single trajectory (ST) viscosities," called "viscuits." This approach is extended here to the bulk viscosity, thermal conductivity, and diffusion coefficient. The PDFs of the four STs expressed in terms of their standard deviations (calculated separately for the positive and negative sides) are shown by MD to be statistically the same for the Lennard-Jones fluid. This PDF can be represented well by a sum of exponentials and is independent of system size and state point in the equilibrium fluid regime. The PDF is not well reproduced by a stochastic model. The PDF is statistically the same as that derived from the potential energy, u, and other thermodynamic quantities, indicating that the transport coefficients are determined quantitatively by and follow closely the time evolution of the underlying energy landscape. The PDFs of out-of-equilibrium supercooled high density states are quite different from those of the equilibrium states.

Quality Improvement Intervention for Universal Lipid Screening in Children Aged 9 to 11 Years

We performed a quality improvement intervention to increase universal lipid screening in well-child visits (age 9 to 11 years): 12-month preintervention; phase 1 (8 months) with provider education, group monthly chart review with feedback, and electronic health record cues to order lipids; and phase 2 (16 months) with electronic health record cues and examination room phlebotomy. Outcomes were compared with clinics having no intervention. In phase 1, immediate treatment effect on the regression line for provider behavior (proportion of visits with lipids ordered) showed 34% increase in intervention and 7% decrease in comparison clinics; patient behavior (phlebotomy completed) showed 19% increase in intervention and 5% decrease in comparison clinics. At the beginning of phase 2, the intervention clinic had average 44% orders entered and 33% phlebotomy completed per well-child visit, and these proportions were maintained. Provider education and chart review with feedback were associated with the greatest gains in outcomes.

Early-Onset Sepsis Risk Calculator Integration Into an Electronic Health Record in the Nursery

BACKGROUND AND OBJECTIVES

An early-onset sepsis (EOS) risk calculator tool to guide evaluation and treatment of infants at risk for sepsis has reduced antibiotic use without increased adverse outcomes. We performed an electronic health record (EHR)-driven quality improvement intervention to increase calculator use for infants admitted to a newborn nursery and reduce antibiotic treatment of infants at low risk for sepsis.

METHODS

This 2-phase intervention included programming (1) an EHR form containing calculator fields that were external to the infant's admission note, with nonautomatic access to the calculator, education for end-users, and reviewing risk scores in structured bedside rounds and (2) discrete data entry elements into the EHR admission form with a hyperlink to the calculator Web site. We used statistical process control to assess weekly entry of risk scores and antibiotic orders and interrupted time series to assess trend of antibiotic orders.

RESULTS

During phase 1 (duration, 14 months), a mean 59% of infants had EOS calculator scores entered. There was wide variability around the mean, with frequent crossing of weekly means beyond the 3σ control lines, indicating special-cause variation. During phase 2 (duration, 2 years), mean frequency of EOS calculator use increased to 85% of infants, and variability around the mean was within the 3σ control lines. The frequency of antibiotic orders decreased from preintervention (7%) to the final 6 months of phase 2 (1%, P < .001).

CONCLUSIONS

An EHR-driven quality improvement intervention increased EOS calculator use and reduced antibiotic orders, with no increase in adverse events.

Measuring heat flux beyond Fourier's law

We use nonequilibrium molecular dynamics to explore the effect of shear flow on heat flux. By simulating a simple fluid in a channel bounded by tethered atoms, the heat flux is computed for two systems: a temperature driven one with no flow and a wall driven, Couette flow system. The results for the temperature driven system give Fourier's law thermal conductivity, which is shown to agree well with experiments. Through comparison of the two systems, we quantify the additional components of the heat flux parallel and normal to the walls due to shear flow. To compute the heat flux in the flow direction, the Irving-Kirkwood equations are integrated over a volume, giving the so-called volume average form, and they are also manipulated to get expressions for the surface averaged and method of planes forms. The method of planes and volume average forms are shown to give equivalent results for the heat flux when using small volumes. The heat flux in the flow direction is obtained consistently over a range of simulations, and it is shown to vary linearly with strain rate, as predicted by theory. The additional strain rate dependent component of the heat flux normal to the wall is obtained by fitting the strain rate dependence of the heat flux to the expected form. As a result, the additional terms in the thermal conductivity tensor quantified in this work should be experimentally testable.

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.

Evaluation of the EntericBio CPE assay for the detection of carbapenemase-producing organisms

Carbapenemase-producing organisms (CPOs) represent an increasing threat in healthcare facilities and detection of these organisms in the diagnostic laboratory can be challenging. The EntericBio CPE (EBCPE) real-time PCR assay (Serosep Ltd) was evaluated for the detection of NDM, KPC, OXA-48-like, VIM, IMP and GES carbapenemase genes from a panel of 145 multidrug-resistant organisms (29 NDM, 35 OXA-48, 21 VIM, 4 OXA-23, 3 KPC, 5 NDM+OXA-48, 3 GES-5, 1 OXA-23+NDM, 1 IMI, 2 IMP-1 and 41 multidrug-resistant carbapenemase-negative isolates). The EBCPE assay performed well, with 100 % sensitivity and specificity for the detection of all genotypes included in the assay. Turnaround time and laboratory workflow were improved compared to culture-based assays. Users must remain aware of the limitations of molecular assays for CPO detection to ensure implementation of the most suitable CPO diagnostic pathways.

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.

Improving the detection of carbapenemase-producing organisms (CPO) in a low-prevalence setting: evaluation of four commercial methods and implementation of an algorithm of testing

PURPOSE

Carbapenemase-producing organisms (CPOs) can be resistant to almost all β-lactams and represent an increasing threat in healthcare facilities. Detection of these organisms in routine diagnostic laboratories is difficult; here we evaluate four commercially available CPO detection assays and assess their suitability for the clinical laboratory.

METHODOLOGY

A panel of 95 clinical multidrug-resistant organisms (22 NDM, 24 OXA-48, 19 VIM, 4 OXA-23, 3 KPC, 4 NDM+OXA-48, 1 OXA23+NDM, 1 IMI, 1 IMP-1, 9 ESBL, 3 derepressed AmpC and 4 inducible AmpC producers) were tested by the RESIST-3 O.K.N., RapidEC CarbaNP, Acuitas Resistome and Xpert Carba-R assays.Results/Key Findings. The commercial assays performed well, with high sensitivities (96.2-100 %) and specificities (all, 100 %). The RapidEC CarbaNP and Acuitas Resistome were able to detect the broadest range of carbapenemase genotypes. The RESIST-3 O.K.N. and Xpert CarbaR had the shortest turnaround times, whilst the RapidEC CarbaNP was the only assay included in this study that could detect previously undescribed genotypes.

CONCLUSION

Using an algorithm of the RapidEC CarbaNP, followed by either the RESIST-3 O.K.N. (Enterobacteriaceae) or the Xpert Carba-R (Pseudomonas aeruginosa and Acinetobacter spp.) on suspect CPOs allowed rapid in-house detection and genotyping of a high proportion of CPOs, reducing turnaround time by up to 7 days.

Towards the Irving-Kirkwood limit of the mechanical stress tensor

The probability density functions (PDFs) of the local measure of pressure as a function of the sampling volume are computed for a model Lennard-Jones (LJ) fluid using the Method of Planes (MOP) and Volume Averaging (VA) techniques. This builds on the study of Heyes, Dini, and Smith [J. Chem. Phys. 145, 104504 (2016)] which only considered the VA method for larger subvolumes. The focus here is typically on much smaller subvolumes than considered previously, which tend to the Irving-Kirkwood limit where the pressure tensor is defined at a point. The PDFs from the MOP and VA routes are compared for cubic subvolumes, V=ℓ3. Using very high grid-resolution and box-counting analysis, we also show that any measurement of pressure in a molecular system will fail to exactly capture the molecular configuration. This suggests that it is impossible to obtain the pressure in the Irving-Kirkwood limit using the commonly employed grid based averaging techniques. More importantly, below ℓ≈3 in LJ reduced units, the PDFs depart from Gaussian statistics, and for ℓ=1.0, a double peaked PDF is observed in the MOP but not VA pressure distributions. This departure from a Gaussian shape means that the average pressure is not the most representative or common value to arise. In addition to contributing to our understanding of local pressure formulas, this work shows a clear lower limit on the validity of simply taking the average value when coarse graining pressure from molecular (and colloidal) systems.

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.

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.

A web-based screening tool for near-port air quality assessments

The Community model for near-PORT applications (C-PORT) is a screening tool with an intended purpose of calculating differences in annual averaged concentration patterns and relative contributions of various source categories over the spatial domain within about 10 km of the port. C-PORT can inform decision-makers and concerned citizens about local air quality due to mobile source emissions related to commercial port activities. It allows users to visualize and evaluate different planning scenarios, helping them identify the best alternatives for making long-term decisions that protect community health and sustainability. The web-based, easy-to-use interface currently includes data from 21 seaports primarily in the Southeastern U.S., and has a map-based interface based on Google Maps. The tool was developed to visualize and assess changes in air quality due to changes in emissions and/or meteorology in order to analyze development scenarios, and is not intended to support or replace any regulatory models or programs.

A Langevin model for fluctuating contact angle behaviour parametrised using molecular dynamics

Molecular dynamics simulations are employed to develop a theoretical model to predict the fluid-solid contact angle as a function of wall-sliding speed incorporating thermal fluctuations. A liquid bridge between counter-sliding walls is studied, with liquid-vapour interface-tracking, to explore the impact of wall-sliding speed on contact angle. The behaviour of the macroscopic contact angle varies linearly over a range of capillary numbers beyond which the liquid bridge pinches off, a behaviour supported by experimental results. Nonetheless, the liquid bridge provides an ideal test case to study molecular scale thermal fluctuations, which are shown to be well described by Gaussian distributions. A Langevin model for contact angle is parametrised to incorporate the mean, fluctuation and auto-correlations over a range of sliding speeds and temperatures. The resulting equations can be used as a proxy for the fully-detailed molecular dynamics simulation allowing them to be integrated within a continuum-scale solver.

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.

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.

Equilibrium fluctuations of liquid state static properties in a subvolume by molecular dynamics

System property fluctuations increasingly dominate a physical process as the sampling volume decreases. The purpose of this work is to explore how the fluctuation statistics of various thermodynamic properties depend on the sampling volume, using molecular dynamics (MD) simulations. First an examination of various expressions for calculating the bulk pressure of a bulk liquid is made, which includes a decomposition of the virial expression into two terms, one of which is the Method of Planes (MOP) applied to the faces of the cubic simulation cell. Then an analysis is made of the fluctuations of local density, temperature, pressure, and shear stress as a function of sampling volume (SV). Cubic and spherical shaped SVs were used within a spatially homogeneous LJ liquid at a state point along the melting curve. It is shown that the MD-generated probability distribution functions (PDFs) of all of these properties are to a good approximation Gaussian even for SV containing only a few molecules (∼10), with the variances being inversely proportional to the SV volume, Ω. For small subvolumes the shear stress PDF fits better to a Gaussian than the pressure PDF. A new stochastic sampling technique to implement the volume averaging definition of the pressure tensor is presented, which is employed for cubic, spherical, thin cubic, and spherical shell SV. This method is more efficient for less symmetric SV shapes.

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.

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.

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.

Large vessel calcification in Takayasu arteritis

We report the novel case of a young woman with Takayasu arteritis, with extensive large vessel disease. The case demonstrates that while mechanisms of vascular calcification are poorly understood, inflammation per se might be sufficient to mediate increased mineral stress leading to vessel calcification, even in the absence of renal impairment.

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.

Cyclooxygenase-1 inhibition prolongs postnatal ovarian follicle lifespan in mice

Menopause is the permanent cessation of menstruation that results from depletion of ovarian germ cells and follicles. Although most animals experience reproductive senescence, the mechanisms differ from that in women, who may live more than one-third of their lives after menopause and consequently face the risk of a number of menopause-associated health problems. Understanding factors that influence ovarian aging may provide strategies to delay or alleviate physiological alterations that take place in postmenopausal women. The germ cell-deficient Wv mice recapitulate follicle loss, prolong postreproductive lifespan, and model many physiological changes that take place in postmenopausal women. Here, using genetic and pharmacological approaches, we found that inhibition of cyclooxygenase-1 but not cyclooxygenase-2 in Wv mice delays germ cell depletion and preserves ovarian follicles. Cyclooxygenase-1 inhibition slows down follicle maturation at the conversion of primary to secondary follicles and prolongs postnatal ovarian follicle lifespan. The current study suggests that inhibition of cyclooxygenase-1 may be able to delay ovarian aging and modulate menopausal timing.

Differential requirement for Dab2 in the development of embryonic and extra-embryonic tissues

BACKGROUND

Disabled-2 (Dab2) is an endocytic adaptor protein involved in clathrin-mediated endocytosis and cargo trafficking. Since its expression is lost in several cancer types, Dab2 has been suggested to be a tumor suppressor. In vitro studies indicate that Dab2 establishes epithelial cell polarity and organization by directing endocytic trafficking of membrane glycoproteins. Dab2 also modulates cellular signaling pathways by mediating the endocytosis and recycling of surface receptors and associated signaling components. Previously, two independent gene knockout studies have been reported, with some discrepancies in the observed embryonic phenotypes. To further clarify the in vivo roles of Dab2 in development and physiology, we designed a new floxed allele to delete dab2 gene.

RESULTS

The constitutive dab2 deleted embryos showed a spectrum in the degree of endoderm disorganization in E5.5 and no mutant embryos persisted at E9.5. However, the mice were grossly normal when dab2 deletion was restricted to the embryo proper and the gene was retained in extraembryonic tissues using Meox2-Cre and Sox2-Cre. Adult Dab2-deficient mice had a small but statistically significant increase in serum cholesterol levels.

CONCLUSION

The study of the new dab2 mutant allele in embryos and embryoid bodies confirms a role for Dab2 in extraembryonic endoderm development and epithelial organization. Experimental results with embryoid bodies suggest that additional endocytic adaptors such as Arh and Numb could partially compensate for Dab2 loss. Conditional deletion indicates that Dab2 is dispensable for organ development, when the vast majority of the embryonic cells are dab2 null. However, Dab2 has a physiological role in the endocytosis of lipoproteins and cholesterol metabolism.

Neurointerventions in children: radiation exposure and its import

BACKGROUND AND PURPOSE

Neurointerventions in children have dramatically improved the clinical outlook for patients with previously intractable cerebrovascular conditions, such as vein of Galen malformations and complex arteriovenous fistulas. However, these complex and sometimes lengthy procedures are performed under fluoroscopic guidance and thus unavoidably expose vulnerable pediatric patients to the effects of ionizing radiation. Recent epidemiologic evidence from a national registry of children who underwent CT scans suggests a higher-than-expected incidence of secondary tumors. We sought to calculate the predicted risk of secondary tumors in a large cohort of pediatric neurointerventional patients.

MATERIALS AND METHODS

We reviewed our cohort of pediatric neurointerventions, tabulated radiation dose delivered to the skin, and calculated the range of likely brain-absorbed doses by use of previously developed mathematical models. The predicted risk of secondary tumor development as a function of brain-absorbed dose in this cohort was then generated by use of the head CT registry findings.

RESULTS

Maximal skin dose and brain-absorbed doses in our cohort were substantially lower than have been previously described. However, we found 1) a statistically significant correlation between radiation dose and age at procedure, as well as number and type of procedures, and 2) a substantial increase in lifetime predicted risk of tumor above baseline in the cohort of young children who undergo neurointerventions.

CONCLUSIONS

Although neurointerventional procedures have dramatically improved the prognosis of children facing serious cerebrovascular conditions, the predicted risk of secondary tumors, particularly in the youngest patients and those undergoing multiple procedures, is sobering.

Increasing Out-of-Hospital Regional Surge Capacity for H1N1 2009 Influenza A Through Existing Community Pediatrician Offices: A Qualitative Description of Quality Improvement Strategies

Objective: To describe initiatives undertaken by a network of community pediatricians to increase a city's surge capacity for patients presenting with influenza-like illnesses during the 2009 H1N1 influenza A pandemic.

Methods: This was a descriptive quality improvement project detailing the measures employed by a network of private practice community pediatricians in Houston, Texas, caring for both insured and uninsured children.

Results: Four categories of interventions were used: enhanced communication, increasing community pediatrician presence, vaccine distribution, and targeted viral diagnosis and antiviral utilization. Promoting communication between clinicians, families, and an affiliated local tertiary care children's hospital allowed for the efficient coordination of resources as well as a unified and consistent message. Increasing access of families to their primary medical home by employing additional clinicians, extending office hours, and locating additional space served to decrease the number of children with low-acuity illness seen in the local emergency centers. Vaccine distribution was enhanced by effective communication between clinicians and families. Finally, targeted antiviral testing and adherence to national recommendations on antiviral utilization enabled judicious utilization of a limited supply of antiviral medications.

Conclusions: Effective communication and improved access to health care enabled children within the network with influenza-like illnesses to continue to be cared for in their medical home. The measures used in response to novel influenza virus outbreaks can be adapted for other situations requiring increased community surge capacity.

(Disaster Med Public Health Preparedness 2012;6:113-116)

Control-volume representation of molecular dynamics

A molecular dynamics (MD) parallel to the control volume (CV) formulation of fluid mechanics is developed by integrating the formulas of Irving and Kirkwood [J. Chem. Phys. 18, 817 (1950)] over a finite cubic volume of molecular dimensions. The Lagrangian molecular system is expressed in terms of an Eulerian CV, which yields an equivalent to Reynolds' transport theorem for the discrete system. This approach casts the dynamics of the molecular system into a form that can be readily compared to the continuum equations. The MD equations of motion are reinterpreted in terms of a Lagrangian-to-control-volume (LCV) conversion function ϑ(i) for each molecule i. The LCV function and its spatial derivatives are used to express fluxes and relevant forces across the control surfaces. The relationship between the local pressures computed using the volume average [Lutsko, J. Appl. Phys. 64, 1152 (1988)] techniques and the method of planes [Todd et al., Phys. Rev. E 52, 1627 (1995)] emerges naturally from the treatment. Numerical experiments using the MD CV method are reported for equilibrium and nonequilibrium (start-up Couette flow) model liquids, which demonstrate the advantages of the formulation. The CV formulation of the MD is shown to be exactly conservative and is, therefore, ideally suited to obtain macroscopic properties from a discrete system.

White spotting variant mouse as an experimental model for ovarian aging and menopausal biology

OBJECTIVE

Menopause is a unique phenomenon in modern women, as most mammalian species possess a reproductive period comparable with their life span. Menopause is caused by the depletion of germ cell-containing ovarian follicles and in laboratory studies is usually modeled in animals in which the ovarian function is removed through ovariectomy or chemical poisoning of the germ cells. Our objective was to explore and characterize the white spotting variant (Wv) mice that have reduced ovarian germ cell abundance, a result of a point mutation in the c-kit gene that decreases kinase activity, as a genetic model for use in menopause studies.

METHODS

Physiological and morphological features associated with menopause were determined in female Wv/Wv mice compared with age-matched wildtype controls. Immunohistochemistry was used to evaluate the presence and number of follicles in paraffin-embedded ovaries. Bone density and body composition were evaluated using the PIXImus x-ray densitometer, and lipids, calcium, and hormone levels were determined in serum using antigen-specific enzyme immunoassays. Heart and body weight were measured, and cardiac function was evaluated using transthoracic echocardiography.

RESULTS

The ovaries of the Wv/Wv females have a greatly reduced number of normal germ cells at birth compared with wildtype mice. The remaining follicles are depleted by around 2 months, and the ovaries develop benign epithelial lesions that resemble morphological changes that occur during ovarian aging, whereas a normal mouse ovary has numerous follicles at all stages of development and retains some follicles even in advanced age. Wv mice have elevated plasma gonadotropins and reduced estrogen and progesterone levels, a significant reduction in bone mass density, and elevated serum cholesterol and lipoprotein levels. Moreover, the Wv female mice have enlarged hearts and reduced cardiac function.

CONCLUSIONS

The reduction of c-kit activity in Wv mice leads to a substantially diminished follicular endowment in newborn mice and premature depletion of follicles in young mice, although mutant females have a normal life span after cessation of ovarian function. The Wv female mice exhibit consistent physiological changes that resemble common features of postmenopausal women. These alterations include follicle depletion, morphological aging of the ovary, altered serum levels of cholesterol, gonadotropins and steroid hormones, decreased bone density, and reduced cardiac function. These changes were not observed in male mice, either age-matched male Wv/Wv or wildtype mice, and are improbably caused by global loss of c-kit function. The Wv mouse may be a genetic, intact-ovary model that mimics closely the phenotypes of human menopause to be used for further studies to understand the mechanisms of menopausal biology.