An in vitro CRISPR screen of cell-free DNA identifies apoptosis as the primary mediator of cell-free DNA release

ABTRACT

Clinical circulating cell-free DNA (cfDNA) testing is now routine, however test accuracy remains limited. By understanding the life-cycle of cfDNA, we might identify opportunities to increase test performance. Here, we profile cfDNA release across a 24-cell line panel and utilize a cell-free CRISPR screen (cfCRISPR) to identify mediators of cfDNA release. Our panel outlines two distinct groups of cell lines: one which releases cfDNA fragmented similarly to clinical samples and purported as characteristic of apoptosis, and another which releases larger fragments associated with vesicular or necrotic DNA. Our cfCRISPR screens reveal that genes mediating cfDNA release are primarily involved with apoptosis, but also identify other subsets of genes such as RNA binding proteins as potential regulators of cfDNA release. We observe that both groups of cells lines identified primarily produce cfDNA through apoptosis. These results establish the utility of cfCRISPR, genetically validate apoptosis as a major mediator of DNA release in vitro, and implicate ways to improve cfDNA assays.

System-level recommendations for improved wellness for gynecologic oncologists: A Society of Gynecologic Oncology Review

Burnout and its negative sequelae are a persistent problem in gynecologic oncology, threatening the health of our physician workforce. Individual-level interventions such as stress management training, physical activity, and sleep hygiene only partially address this widespread, systemic crisis rooted in the extended work hours and stressful situations associated with gynecologic oncology practice. There is an urgent need for systematic, institution-level changes to allow gynecologic oncologists to continue the crucial work of caring for people with gynecologic cancer. We present recommendations for institution-level changes which are grounded in the framework presented by the National Plan for Health Workforce Well-Being by the National Academy of Medicine. These are aimed at facilitating gynecologic oncologists' well-being and reduction of burnout. Recommendations include efforts to create a more positive and inclusive work environment, decrease administrative barriers, promote mental health, optimize electronic medical record use, and support a diverse workforce. Implementation and regular evaluation of these interventions, with specific attention to at-risk groups, is an important next step.

Evaluation and Management of Deficiency of Adenosine Deaminase 2: An International Consensus Statement

Importance

Deficiency of adenosine deaminase 2 (DADA2) is a recessively inherited disease characterized by systemic vasculitis, early-onset stroke, bone marrow failure, and/or immunodeficiency affecting both children and adults. DADA2 is among the more common monogenic autoinflammatory diseases, with an estimate of more than 35 000 cases worldwide, but currently, there are no guidelines for diagnostic evaluation or management.

Objective

To review the available evidence and develop multidisciplinary consensus statements for the evaluation and management of DADA2.

Evidence Review

The DADA2 Consensus Committee developed research questions based on data collected from the International Meetings on DADA2 organized by the DADA2 Foundation in 2016, 2018, and 2020. A comprehensive literature review was performed for articles published prior to 2022. Thirty-two consensus statements were generated using a modified Delphi process, and evidence was graded using the Oxford Center for Evidence-Based Medicine Levels of Evidence.

Findings

The DADA2 Consensus Committee, comprising 3 patient representatives and 35 international experts from 18 countries, developed consensus statements for (1) diagnostic testing, (2) screening, (3) clinical and laboratory evaluation, and (4) management of DADA2 based on disease phenotype. Additional consensus statements related to the evaluation and treatment of individuals with DADA2 who are presymptomatic and carriers were generated. Areas with insufficient evidence were identified, and questions for future research were outlined.

Conclusions and Relevance

DADA2 is a potentially fatal disease that requires early diagnosis and treatment. By summarizing key evidence and expert opinions, these consensus statements provide a framework to facilitate diagnostic evaluation and management of DADA2.

SGO and the elephant that is still in the room: Wellness, burnout and gynecologic oncology

OBJECTIVE

To measure wellness and burnout among gynecologic oncology clinicians and identify trends and at-risk populations to inform future interventions.

METHODS

Gynecologic oncologist (GO) and advanced practice provider (APP) responses to the 2020 Society of Gynecologic Oncology State of the Society survey were analyzed. The Maslach Burnout Inventory criteria for burnout was used. Work-life balance was scored on a 5-point Likert scale. Chi-square tests were used to compare mental health factors and the prevalence of burnout. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for associations between burnout and gender.

RESULTS

543 survey responses were included for analysis. Most GO (54%) and all APP respondents were female. Female GOs were disproportionately affected by burnout particularly in the Northeast (female(F): 40.9% vs male(M): 19.1%, p = 0.007) and South (F: 42.5% vs M:22.9%, p = 0.01). Burnout in female GOs over 40 was 1.79 (CI: 1.13-2.83; p-value 0.01) times higher than similarly aged males. Females in non-private practice experienced burnout 1.66 times that of males in similar positions (CI: 1.18-2.94; p < 0.0001). Female GOs reported the worst work-life balance across all 5 domains. APPs and female GOs experienced more stress and feeling overwhelmed compared to men. GOs were more reluctant to see a mental health professional (p = 0.0003) or take medication (p = 0.009) than APPs.

CONCLUSIONS

Burnout in gynecologic oncology persists in both genders and is felt most acutely by female GOs. APPs are not immune and would benefit from inclusion in future research to mitigate burnout in healthcare clinicians.

Abstract 13: Novel CRISPR screening approach identifies regulators of cell-free DNA release in vitro

Despite the well-documented benefits of circulating tumor DNA (ctDNA) based liquid biopsy, including screening, prognostication, and treatment monitoring, there remain several concerns with its application. Chief among these concerns are imperfect sensitivity and specificity, particularly pre-diagnosis and after tumor resection, when ctDNA burden is low. Cell death, either through apoptosis or necrosis, has been the most widely accepted mechanism of DNA release. Recent studies have also suggested active release through extracellular vesicles as a paradigm for DNA release. However, this pathway remains highly debated in terms of its contribution, mechanism, and even credibility. To address the deficiencies in ctDNA detection in the clinic and the lack of basic mechanistic knowledge of cf/ctDNA release, we performed an in vitro CRISPR screen on MCF10A cells to identify regulators of DNA release. This normal breast epithelial cell line was chosen because MCF10A cells release DNA into cell culture media with a similar fragmentation pattern to that observed in human blood. After lentiviral infection with the genome-wide Brunello CRISPR-Cas9 knockout library, the population of knockouts identified in the genomic DNA of cells attached to the plates was compared to the population of knockouts found in the DNA released into the cell-depleted culture media. Genes with skewed representation were considered potential regulators of DNA release. Our analysis identified several genes in the TRAIL apoptotic pathway including FADD, as well as several genes encoding RNA-binding proteins including Sam68. Knockout of Sam68 and FADD in MCF10As, MDA-MB-468 breast cancer cells, and NCI-H841 lung cancer cells lead to decreases in DNA release. Previous studies have hypothesized that the fragment size of released DNA is dependent on release mechanism. However, the decreases observed in our knockout cell lines were not limited to a specific fragment size of DNA. Application of the small molecule apoptosis inhibitor Z-VAD-FMK also recapitulated the DNA release phenotype seen in our knockout cell lines. From these results, we conclude that apoptosis is the major source of DNA release from cancer cells, and that fragment size is not the indicator of release mechanism it has been presumed to be. Mechanistic studies of DNA release such as this could lead to the ability to modify the amount of ctDNA in circulation, which would significantly improve accurate detection in the clinic.

Citation Format: Brad A. Davidson, Adam X. Miranda, Sarah Croessmann, Ben Ho Park. Novel CRISPR screening approach identifies regulators of cell-free DNA release in vitro [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 13.

The breast is yet to come: current and future utility of circulating tumour DNA in breast cancer

Advances in genomic strategies and the development of targeted therapies have enabled precision medicine to revolutionise the field of oncology. Precision medicine uses patient-specific genetic and molecular information, traditionally obtained from tumour biopsy samples, to classify tumours and treat them accordingly. However, biopsy samples often fail to provide complete tumour profiling, and the technique is expensive and, of course, relatively invasive. Advances in genomic techniques have led to improvements in the isolation and detection of circulating tumour DNA (ctDNA), a component of a peripheral blood draw/liquid biopsy. Liquid biopsy offers a minimally invasive method to gather genetic information that is representative of a global snapshot of both primary and metastatic sites and can thereby provide invaluable information for potential targeted therapies and methods for tumour surveillance. However, a lack of prospective clinical trials showing direct patient benefit has limited the implementation of liquid biopsies in standard clinical applications. Here, we review the potential of ctDNA obtained by liquid biopsy to revolutionise personalised medicine and discuss current applications of ctDNA both at the benchtop and bedside.

Hierarchical tumor heterogeneity mediated by cell contact between distinct genetic subclones

Intratumor heterogeneity is an important mediator of poor outcomes in many cancers, including breast cancer. Genetic subclones frequently contribute to this heterogeneity; however, their growth dynamics and interactions remain poorly understood. PIK3CA and HER2 alterations are known to coexist in breast and other cancers. Herein, we present data that describe the ability of oncogenic PIK3CA mutant cells to induce the proliferation of quiescent HER2 mutant cells through a cell contact-mediated mechanism. Interestingly, the HER2 cells proliferated to become the major subclone over PIK3CA counterparts both in vitro and in vivo. Furthermore, this phenotype was observed in both hormone receptor-positive and -negative cell lines, and was dependent on the expression of fibronectin from mutant PIK3CA cells. Analysis of human tumors demonstrated similar HER2:PIK3CA clonal dynamics and fibronectin expression. Our study provides insight into nonrandom subclonal architecture of heterogenous tumors, which may aid the understanding of tumor evolution and inform future strategies for personalized medicine.

An integrated ultra-high vacuum apparatus for growth and in situ characterization of complex materials

Here, we present an integrated ultra-high vacuum apparatus-named MBE-Cluster -dedicated to the growth and in situ structural, spectroscopic, and magnetic characterization of complex materials. Molecular Beam Epitaxy (MBE) growth of metal oxides, e.g., manganites, and deposition of the patterned metallic layers can be fabricated and in situ characterized by reflection high-energy electron diffraction, low-energy electron diffraction, Auger electron spectroscopy, x-ray photoemission spectroscopy, and azimuthal longitudinal magneto-optic Kerr effect. The temperature can be controlled in the range from 5 K to 580 K, with the possibility of application of magnetic fields H up to ±7 kOe and electric fields E for voltages up to ±500 V. The MBE-Cluster operates for in-house research as well as user facility in combination with the APE beamlines at Sincrotrone-Trieste and the high harmonic generator facility for time-resolved spectroscopy.

Exploring genetic modifiers of Gaucher disease: The next horizon

Gaucher disease is an autosomal recessive lysosomal storage disorder resulting from mutations in the gene GBA1 that lead to a deficiency in the enzyme glucocerebrosidase. Accumulation of the enzyme's substrates, glucosylceramide and glucosylsphingosine, results in symptoms ranging from skeletal and visceral involvement to neurological manifestations. Nonetheless, there is significant variability in clinical presentations amongst patients, with limited correlation between genotype and phenotype. Contributing to this clinical variation are genetic modifiers that influence the phenotypic outcome of the disorder. In this review, we explore the role of genetic modifiers in Mendelian disorders and describe methods to facilitate their discovery. In addition, we provide examples of candidate modifiers of Gaucher disease, explore their relevance in the development of potential therapeutics, and discuss the impact of GBA1 and modifying mutations on other more common diseases like Parkinson disease. Identifying these important modulators of Gaucher phenotype may ultimately unravel the complex relationship between genotype and phenotype and lead to improved counseling and treatments.

Stress-Induced Hyperglycemia in White-Throated and White-Crowned Sparrows: A New Technique for Rapid Glucose Measurement in the Field

Organisms experience stressors, and the physiological response to these stressors is highly conserved. Acute stress activates both the sympathetic nervous system and the hypothalamic-pituitary-adrenal axis, increasing epinephrine, norepinephrine, and glucocorticoids, collectively promoting glucose mobilization. While this is well characterized in mammals, the hyperglycemic response to stress in avian and nonavian reptiles has received less attention. A number of factors, ranging from time of day to blood loss, are reported to influence the extent to which acute stress leads to hyperglycemia in birds. Here we characterized the glycemic response to acute handling stress in two species of free-living sparrows: white-throated sparrows (WTSPs: Zonotrichia albicollis) in St. Mary's County, Maryland, and white-crowned sparrows (WCSPs: Zonotrichia leucophrys) in Tioga Pass Meadow, California. We validated a novel technique for rapid field measurement of glucose using a human blood glucose meter, FreeStyle Lite. As expected, acute handling stress elevated blood glucose at both 15 and 30 min postcapture as compared to baseline for both WTSPs and WCSPs. In addition, handling for 30 min without bleeding had the same hyperglycemic effect as handling with serial bleeds in WCSPs. Finally, body condition that was measured as abdominal fat score predicted stress-induced blood glucose in WTSPs but not in WCSPs. Our results are consistent with the mammalian literature on acute stress and energy mobilization, and we introduce a new field technique for avian field biologists.

Surface octahedral distortions and atomic design of perovskite interfaces

Atomic engineering of perovskite films and interfaces is significantly improved by in situ optimization of reflection high-energy electron diffraction (RHEED) features resulting from surface BO₆ octahedral rotations seen during molecular-beam epitaxy growth. This approach yields Sr-doped manganite films across the phase diagram with magnetotransport properties that are, for the first time, identical to bulk single crystals. Careful structural analysis of manganite/titanate interfaces shows that cation intermixing and unit cell dilations are eliminated, while BO₆ rotations and Jahn-Teller-type elongations are nearly completely suppressed at the interface.

Role of macrophage inflammatory protein-2 in aspiration-induced lung injury

OBJECTIVE

To determine the role of the chemokine, macrophage inflammatory protein (MIP)-2, in the pathogenesis of aspiration-induced lung injury in the rat.

DESIGN

Prospective, randomized, controlled animal study.

SETTING

University research laboratories.

SUBJECTS

Adult, male Long-Evans rats.

INTERVENTIONS

Anesthetized rats underwent induction of lung injury by well-described models of aspiration triggered by intra-tracheal delivery of acid alone, gastric particles alone, or the combination. After injury, induction of MIP-2 messenger RNA in whole lungs and immunoreactive MIP-2 in bronchoalveolar lavage (BAL) fluids was determined. The contribution of MIP-2 to BAL fluid chemotactic activity was defined by using an in vitro chemotaxis assay. The in vivo effect of blocking MIP-2 on pulmonary vascular leak, BAL fluid neutrophils, PaO2/FIO2 ratio, and alveolar-arterial oxygen tension gradient in acid-induced lung injury was determined.

MEASUREMENTS AND MAIN RESULTS

Induction of MIP-2 messenger RNA and protein over time was observed in response to all three stimuli. A significant portion (25% to 41%) of the chemotactic activity in BAL fluids from injured rats was inhibited by anti-MIP-2 antibody. After acid injury, blocking of MIP-2 was associated with a 53% decrease in BAL fluid neutrophils and a 33% decrease in pulmonary vascular leak. Although acid injury both impaired oxygenation and increased venous admixture, in vivo blocking of MIP-2 was associated with improved oxygenation as well as decreased venous admixture.

CONCLUSIONS

MIP-2 was up-regulated during the development of aspiration-induced lung injury in rats. MIP-2 contributed to lung accumulation of neutrophils via a chemotactic mechanism. Although oxygenation and venous admixture are worsened by acid-induced lung injury in vivo, blocking of MIP-2 at the onset of injury improved these physiologic alterations. Because the aspiration event often is witnessed, chemokines may be valid therapeutic targets for inhibiting the subsequent inflammatory response.

Acid aspiration increases sensitivity to increased ambient oxygen concentrations

Previously we have demonstrated that prolonged exposure to 100% ambient oxygen leads to a marked loss in functional lung volume and lung compliance, hypoxemia, and surfactant system abnormalities similar to acute respiratory distress syndrome (ARDS). However, 50% oxygen administration is believed to be safe in most clinical settings. In the present study, we have evaluated the effects of a 24-h exposure to 50% oxygen in rabbits immediately following experimental gastric acid aspiration. Mild hypoxemia, but no changes in mortality, lung volume, lung compliance, surfactant metabolism, or edema formation occurred after 24 h of normoxia postacid aspiration. Conversely, a relatively short (24-h) exposure to 50% oxygen after acid aspiration results in increased pulmonary edema, physical signs of respiratory distress, and mortality, as well as decreased arterial oxygenation, lung volume, lung compliance, and type II alveolar cell surfactant synthesis. These results suggest that acid aspiration alters the "set point" for oxygen toxicity, possibly by "priming" cells through activation of inflammatory pathways. This pathogenic mechanism may contribute to the progression of aspiration pneumonia to ARDS.

Capsular polysaccharide and O-specific antigen divergently modulate pulmonary neutrophil influx in an Escherichia coli model of gram-negative pneumonitis in rats

Enteric gram-negative bacilli cause a severe, often life-threatening pneumonia. An improved understanding of the pathogenesis of this infection may lead to improved treatment. Nearly all of the responsible gram-negative bacilli possess capsular polysaccharides and/or an O-specific antigen as part of their lipopolysaccharide (LPS). We hypothesized that these surface polysaccharides may modulate the pulmonary host response. To investigate this, a rat pneumonitis model was used, and pulmonary neutrophil influx, a critical aspect of host defense, was measured. To assess for the effect of the capsule and O-specific antigen on this host response, three proven, isogenic derivatives that are deficient in capsular polysaccharide alone (CP9.137), the O-specific antigen moiety of the LPS alone (CP921), and both the capsular polysaccharide and O-specific antigen (CP923), as well as their wild-type parent (CP9), were used as challenge strains at various intratracheal challenge inocula (CI). Total lung myeloperoxidase (MPO), a surrogate marker for neutrophils, was measured for 15 h post-bacterial challenge. To determine the effect of capsule and the O-specific antigen on the measured MPO levels, a mathematical model was developed and used to describe the MPO levels as a function of time for each CI of each of the four strains. The results from this analysis demonstrated that in the absence of the K54 capsule, 80.7 times the CI is necessary to achieve the same maximum MPO level relative to K54 positive strains (P < 0.0001). In contrast, a diametric effect was observed in the absence of the O-specific antigen, where 0.13 times the CI was necessary to achieve the same maximum MPO level relative to O4-positive strains (P = 0.0032). No interactive effect was observed between the capsule and the O-specific antigen. These findings demonstrate that these surface polysaccharides modulate pulmonary neutrophil influx and suggest that the K54 capsular polysaccharide is a proinflammatory mediator and that the O4-specific antigen attenuates the proinflammatory response. If these speculations are substantiated, an understanding of how the capsule and the O-specific antigen modulate host response could have significant therapeutic implications. The potential use of biologic modulators directed against the host response, as well as approaches based on inactivating bacterial components (e.g., surface polysaccharides) in attempts to modify sepsis syndromes, could be developed.

Systemic perfluorocarbons suppress the acute lung inflammation after gastric acid aspiration in rats

Perflurocarbons (PFCs) are used during liquid ventilation and as hemoglobin substitutes. PFCs reduce free radical generation and damage to the lung during liquid ventilation. Thus, we examined the effects of parenteral administration of PFCs on lung injury after acid aspiration. Rats were treated with intraperitoneal injection of either FC-77 or IV injection of Fluosol. Controls received intraperitoneal or IV normal saline (NS) before or at the time of injury and then were injured by instillation of NS + HCl (pH = 1.25) into their lungs via a tracheotomy. The animals were exposed to air or 98% oxygen, breathing spontaneously. The rats were injected with 0.05 microCi of (125)I-albumin (bovine serum albumin) before injury. The extent of lung injury was assessed 5 h postinjury by compliance and lung albumin permeability index measurement. Myeloperoxidase (MPO) activity and histologic examination were used to assess neutrophilic infiltration. Both FC-77 and Fluosol decreased the permeability index compared with controls (1.05 +/- 0.08; 1.08 +/- 0. 12, respectively, versus 1.34 +/- 0.21) and improved lung compliance after intratracheal instillation of 1.2 mL/kg of HCl/NS, pH = 1.25 + hyperoxia injury (P < 0.05). Lung MPO activity decreased in the FC-77 group and was associated with a concomitant decrease in neutrophil infiltration. MPO activity of the spleen increased after FC-77 treatment. The administration of FC-77 decreased the severity of lung permeability changes associated with acid in the presence or absence of hyperoxia exposure. These data suggest that attenuation of neutrophilic infiltration by PFCs decreases lung injury.

IMPLICATIONS

Intraperitoneally administered perfluorocarbons in rats attenuate the neutrophilic infiltration in the lung after acid aspiration, thereby decreasing the alveolar protein leakage and improving pulmonary compliance.

High-dose nitric oxide inhalation increases lung injury after gastric aspiration

BACKGROUND

Inhaled nitric oxide is often used in patients with adult respiratory distress syndrome. However, nitric oxide also may be significantly toxic, especially if administered concurrently with hyperoxia. The authors evaluated the isolated effect of nitric oxide and the combined effects of nitric oxide and hyperoxia on lung injury in rats after acid aspiration.

METHODS

Animals were injured by instillation of 1.2 ml/kg hydrogen chloride in low-pH saline (the acid group) or acidified gastric particles (the casp group) into the lungs under halothane anesthesia via a tracheal catheter. Controls received no injury vehicle but rather underwent the surgical process. After recovery from anesthesia, the animals were exposed to 20% or 90% oxygen with or without 20, 40, or 80 ppm nitric oxide for 5 h. The permeability index, alveolar-arterial oxygen difference, the ratio of oxygen pressure to the inspired fraction of oxygen, and the ratio of wet to dry weight were assessed 5 h after injury as indices of lung injury. Data were assessed using analysis of variance.

RESULTS

Each group included 6-10 rats. Exposure to nitric oxide (80 ppm) in air increased protein permeability in the lungs to a permeability index of 1.42+/-0.12 after acid aspiration. The combination of nitric oxide (80 ppm) and hyperoxia further increased protein leakage to a permeability index of 2.1+/-0.25. Exposure to lower concentrations of nitric oxide (e.g., 20 and 40 ppm) increased the permeability index of the lungs (1.44+/-0.21, 1.75+/-0.29, respectively) in the presence of hyperoxia, although it did not affect the permeability index of the lungs during exposure to air. Pretreatment of animals with deferoxamine and methylene blue partially inhibited the adverse effect of hyperoxia and nitric oxide, which suggested a complex underlying mechanism involving both reactive-species generation and pulmonary vasomotor changes.

CONCLUSIONS

These results show that inhaled nitric oxide at 80 ppm for a short duration (5 h) increases the severity of the inflammatory microvascular lung injury after acid aspiration. The pulmonary damage is exacerbated further in the presence of high oxygen concentrations. Although lower concentrations of nitric oxide did not increase the extent of lung injury, longer exposure times need to be assessed.

The role of tumor necrosis factor-alpha in the pathogenesis of aspiration pneumonitis in rats

BACKGROUND

Aspiration pneumonitis is characterized by proteinaceous pulmonary edema and acute infiltration of neutrophils into the alveolar space. This study examined the role of the proinflammatory cytokine, tumor necrosis factor-alpha (TNF-alpha), on the pathogenesis of the injury produced by the different components that may be present in the aspirate, acid, or gastric particles.

METHODS

Rats were injured by intratracheal instillation of a vehicle containing acid or gastric particles. TNF-alpha concentration of bronchoalveolar lavage fluid was determined using a bioassay. upregulation of lung TNF-alpha mRNA was also measured. The effect of intratracheal anti-rat TNF-alpha treatment was assessed by lung protein permeability, blood gases, and lung myeloperoxidase activity.

RESULTS

Injury vehicle alone and acid injury resulted in a small TNF-alpha peak 1-2 h after injury in the lavage fluid. Both particulate and acidic particulate groups produced a much more robust TNF-alpha signal that reached a plateau at 2-4 h after injury and declined at 8 h. Upregulation of TNF-alpha mRNA was only detected in the particulate-containing groups. Acidic particulate exposure yielded a synergistic increase in protein permeability and decrease in blood oxygenation. Anti-TNF-alpha treatment reduced protein permeability and myeloperoxidase activity and increased blood oxygenation in the groups exposed to only acid. Such treatment had no effect on either of the particulate containing injuries.

CONCLUSIONS

TNF-alpha is differentially manifested according to the components that make up the aspirate but the levels of TNF-alpha expression do not correlate with the severity of the resultant injury. However, the reduction in acid-induced lung injury by anti-TNF-alpha treatment indicates that TNF-alpha plays a role in the pathogenesis of aspiration pneumonitis.

Reactive oxygen species contribute to oxygen-related lung injury after acid aspiration

Hyperoxia increases pulmonary damage after acid aspiration. We hypothesize that free radicals play a role in acute lung injury. To examine this hypothesis, we injured rats by intratracheal instillation of acidic isotonic sodium chloride solution (NS) (pH 1.25); NS + gastric particles (particle pH 5.3); or acid + particles (pH 1.25). Animals were exposed to 98% oxygen or air for 5 h. Superoxide (HO2) generation was measured in either an aliquot of white blood cells (WBCs) recovered from bronchoalveolar lavage (BAL) or from blood. Lungs were analyzed for thiobarbituric acid-reactive substances (TBARS) and carbonylated proteins. The antioxidant capacity was measured using a 2-2'-azo-bis-amidinopropane hydrochloride neutralizing assay. Generation of HO2 by WBCs in peripheral blood was greater in animals exposed to 98% O2 (89.8 +/- 12.5 U. min-1.10(5) neutrophils) compared with air exposure (37.5 +/- 9.2 U.min-1.10(5) neutrophils) after combined injury (P < 0.05). Similarly, HO2 generation by WBCs retrieved from BAL was higher in oxygen-exposed rats (987.74 +/- 128 U.min-1.10(5) WBC) compared with air-exposed animals after an identical injury (348 +/- 9.2 U. min-1.10(5) WBC) (P < 0.05). TBARS and carbonylated protein levels in the lungs of oxygen-exposed animals (587.9 +/- 58.6 and 55.8 +/- 3.1 pmol/mg of protein, respectively) were higher than those in air-exposed rats after combined injury (342.8 +/- 15.1 and 28.6 +/- 4.6 pmol/mg of protein, respectively) and compared with air-exposed uninjured rats (340.6 +/- 9.8 and 18.3 +/- 2.8 pmol/mg of protein, respectively; P < 0.01). Antioxidant capacity decreased in acid and combined injury groups (2.41 +/- 0.13 min and 1.94 +/- 0.15 min, respectively) compared with the uninjured group after 5 h of exposure to 98% oxygen (4.85 +/- 0.19 min; P < 0.01). We demonstrated evidence of increased oxidant activity on lipids and proteins in injured lungs after oxygen exposure. The decrease in antioxidant capacity after low pH aspiration with exposure to hyperoxia may contribute to this increase.

IMPLICATIONS

Oxygen administration results in a lung pathology known as oxygen toxicity. This effect is usually not significant if the duration of exposure is limited to < 24 h. In the presence of acute inflammatory lung injury, exposure to hyperoxia results in lung damage in a shorter time. We demonstrate that sufficiently decreased lung antioxidant reserve capacity may be accountable for this early toxicity.

Hyperoxia exacerbates microvascular lung injury following acid aspiration

OBJECTIVES

To examine the effects of an increase in ambient oxygen (O2) concentrations on the extent of inflammatory pulmonary damage following acid aspiration.

DESIGN

Prospective, controlled laboratory study.

SETTINGS

University-affiliated animal research facility.

SUBJECTS

Male, Long Evans rats weighing 250 to 300 g.

INTERVENTION

Rats were injured by instillation of 1.2 mL/kg normal saline solution/HCl, pH= 1.25 (acid), into the lungs via a tracheotomy. Animals were allowed to awaken and were exposed to 21%, 50%, or 98% O2 for 0 to 5 h (n/group > or = 10). In a separate set of experiments, injured rats exposed to 98% O2 were treated with different doses of deferoxamine, just prior to injury. Uninjured rats and rats injured with normal saline solution, pH = 5.3, were used as the control group.

MEASUREMENTS

Injury was determined by assessing lung function (lung compliance and arterial blood gases) and alveolar-capillary wall integrity (wet/dry weight, lung albumin permeability index [PI], and intrapulmonary hemorrhage [HI]).

RESULTS

Intrapulmonary instillation of acid increased PI, HI, and decreased static lung compliance compared to uninjured control animals. Increased ambient oxygen following acid aspiration decreased lung compliance, 1.06+/-0.03 mL/kg/cm H2O, in oxygen-exposed lungs when compared to the lungs exposed to air, 1.26+/-0.04, following a low pH aspirate (p<0.05). An increase in protein leakage into the lung tissue was noted in oxygen-exposed animals, PI=1.33+/-0.10, vs air-exposed rats, 0.89+/-0.07 (p<0.05). The hyperoxia-induced increase in lung injury was prevented by 30 mg/kg or higher deferoxamine treatment, 0.78+/-0.05 (p<0.05). Exposure of animals to 98% O2 for 2 h was sufficient to produce the same increase in microvascular protein leakage as 5-h exposure to O2 following low pH aspirate.

CONCLUSION

Hyperoxia increases acid aspiration-induced inflammatory microvascular lung injury. This appears to be mediated by production of reactive species of O2.

Lip augmentation using the palmaris longus tendon

A case is presented in which the upper lip of a 20-year-old woman was augmented by a graft of palmaris longus tendon-muscle. This technique offers several advantages over other lip enlargement techniques. The primary drawback, in my opinion, is the possibility that lip excursion (smiling, animation) might be restricted by tendon-muscle adherence to lip tissues, although this did not occur in this patient. Experience with larger numbers of patients is necessary before this technique can be endorsed for general use.

Effects of isoflurane and enflurane on intracellular Ca2+ mobilization in isolated cardiac myocytes

BACKGROUND

Enflurane and isoflurane may reduce cardiac contractility by altering mobilization and clearance of intracellular Ca2+ (Ca2+i). It was hypothesized that the negative inotropic actions of these agents involve limiting both membrane Ca2+ entry and altering intracellular Ca2+ release.

METHODS

The Ca2+i transients in rat ventricular myocytes loaded with fura-2 were recorded from a fluorescence microscope. Transients stimulated by membrane depolarization (suction electrode or elevated [K+]o) or 15 mM caffeine to release Ca2+ from the sarcoplasmic reticulum (SR) were analyzed for net amplitude, maximal rate of rise (VR), average rate of decline (VR) in [Ca2+]i, and duration.

RESULTS

Enflurane and isoflurane reduced electrically stimulated Ca2+i transients in a dose-dependent manner. Enflurane depressed the Ca2+i transient amplitude more than isoflurane. Enflurane was more effective than isoflurane in reducing VR and VF in a concentration-dependent manner. At similar concentrations, both enflurane and isoflurane reduced the steady state elevation of [Ca2+]i by 50 mM K+o. Similarly, enflurane and isoflurane depressed caffeine-sensitive release of Ca2+ from the SR. The reduction in the Ca2+i transient because of SR Ca2+ release was greater in enflurane than in equal concentrations of isoflurane. Rates of elevation and decline in [Ca2+]i were also reduced in enflurane and isoflurane.

CONCLUSIONS

The negative inotropic actions of enflurane and isoflurane involve a depression of Ca2+ influx during membrane excitation, as well as a reduction in SR Ca2+ release. Slowed rates of elevation in [Ca2+]i indicate that the latter mechanism may, in part, be caused by alterations in the kinetics of SR Ca2+ release.

Halothane inhibits the intraalveolar recruitment of neutrophils, lymphocytes, and macrophages in response to influenza virus infection in mice

The effect of halothane anesthesia on the influenza A specific immune response and the pathogenesis of infection was evaluated in mice. Three-wk-old CD-1 mice were anesthetized with either 2% halothane for 2 h or ketamine (100 mg/kg intraperitoneally) and subsequently inoculated intranasally with a sublethal dose of influenza type A/PR/8/34 virus. Bronchoalveolar lavage was performed on animals from each group at 4 h postinoculation and daily thereafter for 14 days. Total and differential white blood cell counts were measured in the lavage fluid and the lungs were examined histologically for evidence of injury. Infected mice anesthetized with halothane had lower daily cell counts in the lung than animals anesthetized with ketamine and a marked change in cell type distribution. On Days 4 and 11 postinoculation, there were significantly (P < 0.05) more white blood cells in the lavage fluid of animals anesthetized with ketamine than halothane (mean/mL, 738,000 +/- SEM, 128,000 vs 196,000 +/- 51,400, respectively, and 1,020,000 +/- 227,000 vs 117,000 +/- 34,600, respectively). Differential counts were significantly higher (P < 0.05) in the ketamine group compared to the halothane for neutrophils on Day 4 (452,000 +/- 77,900 vs 72,000 +/- 46,000, respectively) and on Day 11 for lymphocytes (340,000 +/- 59,000 vs 33,000 +/- 17,000, respectively) and macrophages (480,000 +/- 120,000 vs 130,000 +/- 61,000). Infected mice that were given ketamine were qualitatively "sicker" than the halothane-treated group as evidenced by the appearance of ruffled fur, tachypnea, and cachexia. Animals anesthetized with ketamine demonstrated a greater degree of pulmonary histopathology including diffuse infiltration of macrophages, neutrophils, hemorrhage, and fibrin deposition.(ABSTRACT TRUNCATED AT 250 WORDS)

Digital imaging in the radiation oncology environment: a personal computer local area network solution

Personal computer (PC) driven digital imaging devices are now becoming available in the market place for use in radiation oncology to produce what are known as real time portal images. These limited contrast images are used to verify the patient anatomy under treatment by megavoltage x-rays and are a vital part of the patient treatment. The current generation of devices can produce both single and movie loop images in real time for physician review and approval. To disseminate these images and other digital images used in the planning and delivery of radiation therapy, a PC-based picture archiving and communications system has been developed that is tailored to the special needs of radiation oncology.

Characterization of a halothane-resistant strain of measles virus

A strain of measles virus (MVr) whose replication demonstrated increased resistance to halothane (2-bromo-2-chloro-1,1,1-trifluoroethane) exposure compared with the susceptible parental strain (MVs) is described. After exposure to a 1.2% halothane concentration, substantial amounts of the measles virus H protein were detected in MVr-infected Vero cell lysates by immunoprecipitation and polyacrylamide gel electrophoresis or by quantitative immunofluorescence staining. The protein was barely detectable in identically treated MVs-infected lysates, however. The recovery of all other measles virus proteins studied was the same in MVr- and MVs-infected cells at this anesthetic concentration. Thus, the altered expression of a single gene product appears to be responsible for the observed halothane resistance.

Effect of general anesthetics and pressure on aerobic metabolism of monkey kidney cells

The authors examined the inhibition of aerobic metabolism in monkey kidney cell cultures exposed to halothane, enflurane, and isoflurane. The ability of hyperbaric pressure to reverse the halothane-induced metabolic inhibition also was examined. Incubation of two monkey kidney cell lines for 24 h with clinically equipotent concentrations (2.6 MAC) of halothane, enflurane, or isoflurane vapors increased the concentration of lactate in the media by 126 to 244% relative to nonexposed control cultures. The increased rate of lactate accumulation was proportional to the concentration of halothane and was accompanied by a decrease in media pH. Removal of halothane restored the normal rate of lactate production. Hyperbaric pressures of 25, 50, and 100 atmospheres did not alter the halothane-stimulated rate of lactate production relative to non-anesthetic-treated controls, although pressure alone did depress the rate of lactate accumulation in all cultures. The stimulation of lactate production likely reflects the known ability of halothane to inhibit mitochondrial respiration. The failure of pressure to reverse the stimulation of lactate production by halothane suggests that inhibition of mitochondrial metabolism cannot be reversed by pressure.

Effect of halothane on the replication of animal viruses

Five RNA- and two DNA-containing viruses were propagated in Vero cells and tested for their ability to replicate in the presence of halothane (2-bromo-2-chloro-1,1,1-trifluoroethane), a commonly used inhalational anesthetic. Halothane did not affect poliovirus replication at any anesthetic concentration tested, but all other viruses were either partially or totally inhibited by clinical doses of the anesthetic. Replication of Sendai virus, simian virus 40, vesicular stomatitis virus, and herpes simplex virus type 1 were moderately inhibited by halothane exposure. At concentrations of 2.2% (vol/vol) halothane, peak virus titers were reduced by ca. 2 orders of magnitude for vesicular stomatitis virus and simian virus 40, 3.5 orders of magnitude for Sendai virus, and 4 orders of magnitude for herpes simplex virus. Newcastle disease virus and measles virus were the most susceptible to exposure to halothane. Total inhibition of the replication of these viruses occurred at 1.6 to 2.0% halothane. All of the viruses whose replication was susceptible to the action of halothane were inhibited in a concentration-dependent manner. Furthermore, with the exception of simian virus 40, the inhibition of the replication of all viruses was reversible after halothane removal, although total recovery of virus synthesis was not observed unless the culture medium was changed or the pH was adjusted after anesthetic removal.

Concentric circle operation for massive gynecomastia to excise the redundant skin

A technique is described for excising the excess skin in gynecomastia operations, using a concentric "circle" design to remove a calculated amount in the vertical in the horizontal directions. The sole residual scar is a circular one around the periphery of the areola.