Assessing readiness factors for implementation of LGBTQ+ affirmative primary care initiatives: Practice implications from a mixed-method study

INTRODUCTION

Access and utilization barriers in primary care clinics contribute to health disparities that disproportionately affect lesbian, gay, bisexual, transgender, and queer (LGBTQ+) people. Implementing inclusive practice guidelines in these settings may decrease disparities. The purpose of this exploratory/developmental study is to identify key issues affecting the readiness of primary care clinics to implement such guidelines.

METHODS

Using a concurrent mixed-method research design, we conducted surveys, interviews, and focus groups with 36 primary care personnel in clinics in New Mexico, USA, to examine readiness to implement LGBTQ+ inclusive guidelines, analyzing factors affecting motivation, general organizational capacity, and innovation-specific capacity. We supplemented these data by documenting LGBTQ+ inclusive policies and practices at each clinic. We undertook descriptive analyses and between-subscale comparisons controlling for within-rater agreement of the survey data and iterative coding and thematic analysis of the qualitative data.

RESULTS

Quantitatively, participants reported significantly more openness toward adopting guidelines and attitudinal awareness for developing LGBTQ+ clinical skills than clinical preparedness, basic knowledge, and resources to facilitate implementation. Six themes derived from the qualitative findings corroborate and expand on these results: (1) treating all patients the same; (2) addressing diversity in and across LGBTQ+ populations; (3) clinic climates; (4) patient access concerns; (5) insufficient implementation support; and (6) leadership considerations.

CONCLUSION

This study demonstrates that personnel in primary care clinics support initiatives to enhance service environments, policies, and practices for LGBTQ+ patients. However, drawing on Iris Young's theory of structural injustice, we found that neutralizing discourses that construct all patients as the same and time/resource constraints may diminish motivation and capacity in busy, understaffed clinics serving a diverse clientele and reinforce inequities in primary care for LGBTQ+ people. Efforts are needed to build general and innovation-specific capacities for LGBTQ+ initiatives. Such efforts should leverage implementation teams, organizational assessments, education, leadership support, community engagement, and top-down incentives.

Enhancing primary care services for diverse sexual and gender minority populations: a developmental study protocol

INTRODUCTION

Compared with heterosexual, cisgender populations, sexual and gender minority (SGM) people are more likely to suffer from serious health conditions and insufficient access to health services. Primary care is at the frontlines of healthcare delivery; yet, few clinics have resources or mechanisms in place to meet SGM patient needs. This developmental study protocol focuses on reducing health disparities among SGM patients by identifying, adapting and developing SGM practice guidelines/recommendations and implementation strategies for primary care clinics in urban and rural New Mexico. Using input from patients, healthcare advocates and providers, and researchers, the study will pilot a practice parameter and implementation toolkit to promote SGM-specific cultural competence at multiple service delivery levels.

METHODS AND ANALYSIS

We will recruit providers/staff from four Federally Qualified Health Centers (FQHCs) serving ethnically and geographically diverse communities. Incorporating the Implementation of Change Model and an intersectionality perspective, data collection includes a systematic review of SGM-specific practice guidelines/recommendations, focus groups and semistructured interviews, quantitative surveys and the Nominal Group Technique (NGT) with providers/staff. We will categorise guidelines/recommendations identified through the review by shared elements, use iterative processes of open and focused coding to analyse qualitative data from focus groups, interviews and the NGT, and apply descriptive statistics to assess survey data. Findings will provide the foundation for the toolkit. Focus groups with SGM patients will yield supplemental information for toolkit refinement. To investigate changes in primary care contexts following the toolkit's pilot, we will undertake systematic walkthroughs and document review at the FQHCs, analysing these data qualitatively to examine SGM inclusiveness. The structured data-informed Plan-Do-Study-Act method will enable further revision of the toolkit. Finally, focus groups, interviews and quantitative surveys with providers/staff will highlight changes made in the FQHCs to address SGM patient needs, barriers to sustainment of changes, satisfaction, acceptability, usability and feasibility of the toolkit.

ETHICS AND DISSEMINATION

The study has been reviewed and approved by the Pacific Institute for Research and Evaluation Institutional Review Board. Informed consent will be obtained from all participants before their involvement in research activities begins. Study results will be actively disseminated through peer-reviewed journals, conference presentations, social media and the internet, and community/stakeholder engagement activities.

Structural competency in emergency medicine services for transgender and gender non-conforming patients

In this formative qualitative research, we draw upon the concepts of structural vulnerability and structural competency to examine how transgender and gender non-conforming (TGGNC) patients and healthcare personnel experience service delivery in Emergency Departments (EDs), and how this experience can be improved upon. Between October 2016 and June 2017, we undertook 31 semi-structured interviews with TGGNC patients (n = 11) and physicians (n = 6), nurses (n = 7), and non-clinical staff (n = 7) in four community-based EDs in New Mexico. Our iterative coding and analysis process resulted in eight sets of findings: (1) reasons why TGGNC patients seek care from EDs; (2) perceptions about and experiences of TGGNC patients; (3) relevance of gender identity and sex at birth; (4) bureaucracy and communication; (5) spatial considerations; (6) preparing providers and staff to care for TGGNC patients; (7) the lack of resources for structural prescriptions; and (8) respect, humanity, and sameness. Findings suggest that structural issues adversely impact the health and wellbeing of TGGNC patients and service-delivery practices in the ED. We describe study implications for training ED personnel and modifying this practice setting to prevent delayed care and ensure appropriate services for TGGNC patients in need of structurally competent emergency medicine.

Theoretical and experimental approaches to the deposition and clearance of ultrafine carcinogens in the human respiratory tract

INTRODUCTION

  Although inhaled ultrafine particles (UFPs) represent serious lung burdens and are thus responsible for a remarkable number of respiratory diseases (including cancer), only limited information on their deposition and clearance in the lung compartments is available. The study presented here tries to overcome this deficit by using a detailed theoretical approach to UFP behavior in the lungs.

METHODS

  The deposition model used in this context is based upon a stochastic lung geometry and the generation of single-particle trajectories in the tracheobronchial tree according to the random walk algorithm. Simulation of UFP clearance is conducted with the help of a multi-compartment model that considers cellular/non-cellular sites of temporary particle storage as separate compartments.

RESULTS

  As predicted by the models and confirmed by experimental findings, deposition of UFPs by Brownian motion takes place in both the upper and lower compartments of the respiratory tract. Alveolar accumulation of particulate mass increases proportionally with the inhalative flow rate. Clearance of UFPs is chiefly dominated by slow mechanisms with respective half-times ranging from several days to months.

DISCUSSION

  Modeling of UFP behavior in the respiratory tract represents an appropriate tool for forthcoming medical studies on this particle class, but it needs to be subjected to further refinements. •  As outlined by this study, alveolar deposition of UFPs, correlating with a noticeable risk of malignant transformations and cancer development, is determined by a number of factors, including effective particle size and velocity of particle transport in the conducting airways. •  With the help of appropriately validated models, respective predictions on the pulmonary burdens of UFP after short-term or long-term exposure can be made. In the case of subjects suffering from bronchial and/or alveolar UFP overloads, respective clearance approaches may be applied to simulate particle removal scenarios.

Theoretical approach to the hit probability of lung-cancer-sensitive epithelial cells by mineral fibers with various aspect ratios

BACKGROUND

  Inhalation of fibers may lead to the damage and, as a further consequence, to the malignant transformation of specific (most of all non-ciliated) cells of the bronchial and bronchiolar airway epithelium. In order to accurately estimate the cancer risk induced by inhaled fibers, hit probabilities of non-ciliated (secretory) cells by mineral fibers (asbestos and chrysotile) were computed.

METHODS

  Besides the use of a stochastic lung geometry and a particle transport/deposition model being based upon the random-walk algorithm, histological data of cell distributions in the human lungs were applied for the theoretical calculations. Diameters of computer-generated fibers ranged from 0.1 µm to 10 µm, whilst two values (3 and 100) were selected for the aspect ratios (ratios of fiber length to fiber diameter), thereby simulating the behavior of short and very long fibrous particles.

RESULTS

  According to the modeling results, the highest regional hit probabilities (up to 10%) are available for fibers with a diameter of 1.0 µm, whereby cells of the bronchiolar compartment represent a preferential target of these particles. For fibers with a diameter of 0.1 µm, bronchiolar hit probabilities reach 2-3%, whereas fibers with a diameter of 10 µm penetrate to the peripheral lung parts with only low amounts (<0.1%). A change of the inhalation conditions from sitting to light-work breathing enhances the extrathoracic and bronchial filtering of large particles (diameter ≥1 µm), whilst penetration of small particles towards distal lung airways is subject to a reinforcement. Further refinement of hit probabilities by considering single airway generations results in the circumstance that fibers with diameters ≤1.0 µm preferably collide with cancer-sensitive cells of airway generations 12-15. In contrast, fibers with a diameter of 10 µm mainly represent a hazard for cancer-sensitive cells being located in the uppermost airways. A change of breathing conditions both supports the effect of short fibers and enhances the filtering of long ones.

CONCLUSION

  Based upon the results of this contribution it can be concluded that highest cancer risk is generated by the inhalation of mineral fibers with diameters ≤1.0 µm, whereby fiber length has to be classified as a parameter with lower importance.

Deposition and cellular interaction of cancer-inducing particles in the human respiratory tract: Theoretical approaches and experimental data

Inhaled particles that are deposited on the epithelial surface of the human respiratory tract (HRT) may act as serious health hazards, in the worst case inducing the development of various types of lung cancer. In the past, several particle types, such as asbestos fibers, hard wood dust and cigarette smoke were identified and classified as human carcinogens. Due to their different physical and chemical properties these particles are characterized by remarkable discrepancies concerning their transport, deposition, and epithelial interaction in the HRT. In order to continuously increase the knowledge on carcinogenic particle behavior in the HRT, theoretical models describing single stages of particulate action in the lung airways were developed over the last few decades. With the help of these mathematical approaches physical characteristics of aerosolized drugs as well as protocols of inhalative therapies for the treatment of lung diseases could be significantly optimized. In addition, new experimental setups for the enlightenment of possible mechanisms underlying particle-lung interaction were, among other things, founded upon the results of theoretical computations. This review summarizes the efforts and advances of theoretical lung modeling from the early 1970s till today, thereby mainly directing the attention to the simulation of carcinogenic particle behavior in the HRT.

Antibody-based targeting of alternatively spliced tissue factor: a new approach to impede the primary growth and spread of pancreatic ductal adenocarcinoma

Alternatively spliced Tissue Factor (asTF) is a secreted form of Tissue Factor (TF), the trigger of blood coagulation whose expression levels are heightened in several forms of solid cancer, including pancreatic ductal adenocarcinoma (PDAC). asTF binds to β1 integrins on PDAC cells, whereby it promotes tumor growth, metastatic spread, and monocyte recruitment to the stroma. In this study, we determined if targeting asTF in PDAC would significantly impact tumor progression. We here report that a novel inhibitory anti-asTF monoclonal antibody curtails experimental PDAC progression. Moreover, we show that tumor-derived asTF is able to promote PDAC primary growth and spread during early as well as later stages of the disease. This raises the likelihood that asTF may comprise a viable target in early- and late-stage PDAC. In addition, we show that TF expressed by host cells plays a significant role in PDAC spread. Together, our data demonstrate that targeting asTF in PDAC is a novel strategy to stem PDAC progression and spread.

Inhalation of nanoplatelets - Theoretical deposition simulations

Primary objective of the contribution was the theoretical prediction of nanoplatelet deposition in the human respiratory tract. Modeling was founded on the hypothetical inhalation of graphene nanoplatelets (GNP) measuring 0.01 and 0.1μm in thickness and adopting a projected area diameter of 1-30μm. Particle uptake was assumed to take place with inhalation flow rates of 250, 500, 750, and 1000cm³s^-1, respectively. For an appropriate description of pulmonary particle behavior, transport of GNP in a stochastic lung structure and deposition formulae based on analytical and numerical studies were presupposed. The results obtained from the theoretical approach clearly demonstrate that GNP with a thickness of 0.01μm deposit in the respiratory tract by 20-50%, whereas GNP with a thickness of 0.1μm exhibit a deposition of 20-90%. Larger platelets deposit with higher probability than small ones. Increase of inhalation flow rate is accompanied by decreased deposition in the case of thin GNP, whilst thicker GNP are preferably accumulated in the extrathoracic region. Generation-specific deposition ranges from 0.05 to 7% (0.01μm) and from 0.05 to 9%, with maximum values being obtained in airway generation 20. In proximal airway generations (0-10), deposition is increased with inhalation flow rate, whereas in intermediate to distal generations a reverse effect may be observed. Health consequences of GNP deposition in different lung compartments are subjected to an intense debate.

Computer-aided generation and lung deposition modeling of nano-scale particle aggregates

The study sets its main focus on the introduction of a random-walk-based model for the generation of variably shaped particle aggregates consisting of a predefined number of spherical components. With the help of a well-defined algorithm, the user is enabled to select between isodimensional, chain-like and platelet-like aggregates, for which related aerodynamic parameters (dynamic shape factors, volume-equivalent diameters, aerodynamic diameters) are determined automatically. The theoretical approach for random aggregate construction is directly connected with the previously developed stochastic particle transport and deposition model. Thereby, individually shaped aggregates may be provided for each random-walk scenario taking place in the almost realistic lung structure. Preliminary application of the aggregate generation model was carried out by assuming single components with a constant diameter of 1 nm and unit-density (1 g cm^-3) and variably shaped aggregates consisting of 10, 100 and 1000 components. Inhalation of the aggregate-loaded aerosol into lungs of average size (FRC = 3300 mL) was supposed to take place under sitting, light-exercise and heavy-exercise conditions. Results obtained from deposition modeling clearly show that, independent of aggregate geometry, total deposition declines with increasing number of components included in the particulate construct, but experiences a continuous enhancement with rising inhalation flow rate. Among the predefined geometric categories, platelet-like aggregates are distinguished by lowest deposition and isodimensional clusters by highest. While isodimensional aggregates preferentially deposit in the extrathoracic and bronchial airways, chain-like and platelet-like aggregates exhibit a significantly increased tendency to hit the alveolar walls.

Theoretical diagnosis of emphysema by aerosol bolus inhalation

BACKGROUND

The present contribution deals with the theoretical description of aerosol bolus dispersion in lungs being affected by different manifestations of emphysema. The work constructs the hypothesis that each manifestation of emphysema exhibits specific properties with regard to the dispersion of inhaled and exhaled aerosol boluses as well as the deposition of particles from the aerosol pulse.

METHODS

For an appropriate simulation of single emphysematous manifestations, a previously developed model assuming (I) a random variation of alveolar diameters, (II) an exact localization of diseased structures, and (III) a realistic balance between alveolar air volume and number of air sacs was applied. Dispersion of inhaled and exhaled aerosol boluses was simulated by using the mathematical concept of effective diffusivities. Computations were conducted for an average adult lung (FRC =3,300 mL), symmetric breath-cycles with a length 8 s, and inhalation flow rates of 250 mL/s. Particles used for the model predictions had a uniform diameter of 0.84 µm and a density of 1 g/cm³.

RESULTS

According to the theoretical data obtained from the model highest aerosol bolus dispersion may be observed in lungs affected by panacinar and bullous emphysema, whereas centriacinar and paraseptal emphysema cause a significant reduction of the phenomenon. Also other statistical parameters exhibit partly remarkable differences among the studied manifestations. Particle deposition in lungs affected by bullous emphysema falls below that of lungs impaired by the other types of emphysema by 2%-50%.

CONCLUSIONS

From the hypothetical results presented in this study it may be concluded that aerosol bolus inhalation bears a certain potential for the diagnosis of emphysematous structures and, if applied with sufficient accuracy, also for the distinction of single manifestations of emphysema. For a successful use of the technique, however, all statistical bolus parameters and particle deposition have to be subjected to a detailed evaluation.

Bioaerosols in the lungs of subjects with different ages-Part 2: clearance modeling

BACKGROUND

The present contribution deals with theoretical aspects regarding biogenic particle clearance from various lung structures of probands with different ages (1, 5, 15, 20 y). With reference to part 1 of the study, particles varying in size and shape are subject to a detailed analysis. The main goal of the investigation consists in an increase of our knowledge concerning the clearance behaviour of bioparticles and its dependence upon various physiological and anatomical factors.

METHODS

Theoretical clearance of biogenic particles was subdivided into four main phases, namely fast bronchial clearance, slow bronchial clearance, fast alveolar clearance, and slow alveolar clearance. All of these phases were simulated by using a well validated stochastic modeling approach, where the main focus is set on the randomly varied particle mass transfer between main compartments of the human respiratory tract. Whilst effects of particle geometry on clearance were approximated by application of the projective-diameter concept, age dependence of the particle removal process was expressed by the experimentally proven relationship between bronchial mucus velocities and morphometry of the airway tree.

RESULTS

According to the results of the theoretical simulations efficiency of fast bronchial clearance, expressed by the 24-h-retention value, exhibits a negative correlation with proband's age, whereas the other clearance phases are characterized by a rather conservative behaviour among the different age categories. Highest clearance rates may be observed for very fine (<0.01 µm) and very coarse particles (>5 µm) preferentially deposited in the upper bronchial airways, whilst large particles accumulated in the alveoli may be stored there for several months to years.

CONCLUSIONS

The study comes to the conclusion that infants and children dispose of an enhanced bronchial clearance efficiency with respect to adolescents and adults, which results in a faster removal of particulate substances accumulated in the upper bronchial regions. Particles escaping from the natural filtering process in the upper airways and undergoing alveolar deposition are subject to identical clearance scenarios among the age groups and may represent remarkable health hazards.

Local lung deposition of ultrafine particles in healthy adults: experimental results and theoretical predictions

BACKGROUND

Ultrafine particles (UFP) of biogenic and anthropogenic origin occur in high numbers in the ambient atmosphere. In addition, aerosols containing ultrafine powders are used for the inhalation therapy of various diseases. All these facts make it necessary to obtain comprehensive knowledge regarding the exact behavior of UFP in the respiratory tract.

METHODS

Theoretical simulations of local UFP deposition are based on previously conducted inhalation experiments, where particles with various sizes (0.04, 0.06, 0.08, and 0.10 µm) were administered to the respiratory tract by application of the aerosol bolus technique. By the sequential change of the lung penetration depth of the inspired bolus, different volumetric lung regions could be generated and particle deposition in these regions could be evaluated. The model presented in this contribution adopted all parameters used in the experiments. Besides the obligatory comparison between practical and theoretical data, also advanced modeling predictions including the effect of varying functional residual capacity (FRC) and respiratory flow rate were conducted.

RESULTS

Validation of the UFP deposition model shows that highest deposition fractions occur in those volumetric lung regions corresponding to the small and partly alveolated airways of the tracheobronchial tree. Particle deposition proximal to the trachea is increased in female probands with respect to male subjects. Decrease of both the FRC and the respiratory flow rate results in an enhancement of UFP deposition.

CONCLUSIONS

The study comes to the conclusion that deposition of UFP taken up via bolus inhalation is influenced by a multitude of factors, among which lung morphometry and breathing conditions play a superior role.

Morphology and development of the accessory glands in various female cricket species

The study presents new results with regard to the morphometric and ultrastructural development of the accessory glands in females of the three cricket species Gryllus bimaculatus, Gryllus assimilis, and Acheta domesticus. Furthermore, possible age-dependence of secretory productivity of single organs was analyzed by application of the ligature technique introduced in a previous contribution. Within the first 12 days of the adult phase, the accessory glands of all investigated cricket species exhibit a significant increase in length and width which assumes values between 50 and 100%. This gland growth is rather the result of a continuous increase in cellular volume and less that of mitotic cell propagation. In all species height and width of single gland cells increase by 60-80% within the studied time interval. These changes in morphometry are commonly accompanied by ultrastructural modifications. Total glandular secretion is subject to an increase from the 5th to the 12th day of adult age. This development corresponds well with the number of eggs contemporaneously oviposited into the substrate and thus underlines the hypothesis, according to which the main function of the secretion consists in acting as a lubricant for the facilitated transport of the oocytes through the ovipositor.

Total deposition of ultrafine particles in the lungs of healthy men and women: experimental and theoretical results

BACKGROUND

Inhaled ultrafine particles (UFP) may induce greater adverse respiratory effects than larger particles occurring in the ambient atmosphere. Due to this potential of UFP to act as triggers for diverse lung injuries medical as well as physical research has been increasingly focused on the exact deposition behavior of the particles in lungs of various probands. Main purpose of the present study was the presentation of experimental and theoretical data of total, regional, and local UFP deposition in the lungs of men and women.

METHODS

Both experiments and theoretical simulations were carried out by using particle sizes of 0.04, 0.06, 0.08, and 0.10 µm [number median diameters (NMD)]. Inhalation of UFP took place by application of predefined tidal volumes (500, 750, and 1,000 mL) and respiratory flow rates (150, 250, 375, and 500 mL·s(-1)). For male subjects a functional residual capacity (FRC) of 3,911±892 mL was measured, whereas female probands had a FRC of 3,314±547 mL. Theoretical predictions were based on (I) a stochastic model of the tracheobronchial tree; (II) particle transport computations according to a random walk algorithm; and (III) empirical formulae for the description of UFP deposition.

RESULTS

Total deposition fractions (TDF) are marked by a continuous diminution with increasing particle size. Whilst particles measuring 0.04 µm in size deposit in the respiratory tract by 40-70%, particles with a size of 0.10 µm exhibit deposition values ranging from 20% to 45%. Except for the largest particles studied here TDF of female probands are higher than those obtained for male probands. Differences between experimental and theoretical results are most significant for 0.10 µm particles, but never exceed 20%. Predictions of regional (extrathoracic, tracheobronchial, alveolar) UFP deposition show clearly that females tend to develop higher tracheobronchial and alveolar deposition fractions than males. This discrepancy is also confirmed by airway generation-specific deposition, which is permanently higher in women than in men.

CONCLUSIONS

From the experimental data and modeling predictions it can be concluded that females bear a slightly higher potential to develop lung insufficiencies after exposure to UFP than males. Besides higher deposition fractions occurring in female subjects, also total lung deposition dose is noticeably enhanced.

Bioaerosols in the lungs of subjects with different ages-part 1: deposition modeling

BACKGROUND

In this contribution the inhalation and deposition of bioaerosols including particles with various shapes and sizes were investigated for probands with different ages (1, 5, 15 and 20 y). The study should help to increase our knowledge with regard to the behavior of variably shaped and sized particles in lungs being subject to different developmental stages.

METHODS

Simulation of particle transport and deposition in single structures of the respiratory tract was conducted by using a stochastic model of the tracheobronchial tree and well-validated analytical and empirical deposition formulae. Possible effects of particle geometry on deposition were taken into consideration by application of the aerodynamic diameter concept. Age-dependent lung morphometry and breathing parameters were computed by using appropriate scaling factors.

RESULTS

Theoretical simulations came to the result that bioparticle deposition in infants and children clearly differs from that in adolescents and adults insofar as the amount of deposited mass exhibits a positive correlation with age. Nose breathing results in higher extrathoracic deposition rates than mouth breathing and, as a consequence of that, lower particle amounts are enabled to enter the lung structures after passing the nasal airways. Under sitting breathing conditions highest alveolar deposition rates were calculated for particles adopting aerodynamic diameters of 10 nm and 4 µm, respectively.

CONCLUSIONS

The study comes to the conclusion that bioparticles have a lower chance to reach the alveoli in infants' and children's lungs, but show a higher alveolar deposition probability in the lungs of adolescents and adults. Despite of this circumstance also young subjects may increasingly suffer from biogenic particle burden, when they are subject to a long-term exposure to certain bioaerosols.

Spatial visualization of theoretical nanoparticle deposition in the human respiratory tract

BACKGROUND

Although nanoparticles and their hazardous effects on human health are well elucidated meanwhile, inhalation and distribution of these materials in the human respiratory tract still represent partly enigmatic phenomena. Main objective of the present study was the detailed description of a mathematical method, with the help of which spatial distributions of nanoparticles deposited in the tracheobronchial tree may be visualized appropriately.

METHODS

The technique is founded on a stochastic model of the bronchial network, within which inhaled particles follow individual, randomly selected trajectories. The lengths of these random paths depend on the airway-specific deposition probabilities calculated for the particles and the duration of the breath cycle. Positions of the deposited material were determined by computation of the exact lengths of individual particle trajectories and the orientation of single path segments within a Cartesian coordinate system, where the z-direction corresponds with the trachea. For a better quantification of the particle distribution and its eventual comparison with experimental data particle coordinates were fitted into a voxel grid [1 voxel = (0.467 cm)(3)]. Particle deposition is chiefly controlled by diffusive processes, whereas deposition mechanisms associated with inertia or gravity play a subordinate role.

RESULTS

Deposition patterns were visualized for particles with sizes of 1, 10, and 100 nm. As clearly demonstrated by the results obtained from the modeling procedure, under normal breathing conditions 1-nm particles tend to deposit in the upper airways, whilst 10- and 100-nm particles are preferably accumulated in the airways of the central and peripheral lung. The particle dose deposited in the extrathoracic and thoracic airways within one breath cycle significantly declines with increasing particle size.

CONCLUSIONS

Based on the predictions presented in this study possible consequences of nanoparticle inhalation to the health of subjects increasingly exposed to these airborne materials were discussed.

A computer model for the simulation of nanoparticle deposition in the alveolar structures of the human lungs

BACKGROUND

According to epidemiological and experimental studies, inhalation of nanoparticles is commonly believed as a main trigger for several pulmonary dysfunctions and lung diseases. Concerning the transport and deposition of such nano-scale particles in the different structures of the human lungs, some essential questions are still in need of a clarification. Therefore, main objective of the study was the simulation of nanoparticle deposition in the alveolar region of the human respiratory tract (HRT).

METHODS

Respective factors describing the aerodynamic behavior of spherical and non-spherical particles in the inhaled air stream (i.e., Cunningham slip correction factors, dynamic shape factors, equivalent-volume diameters, aerodynamic diameters) were computed. Alveolar deposition of diverse nanomaterials according to several known mechanisms, among which Brownian diffusion and sedimentation play a superior role, was approximated by the use of empirical and analytical formulae. Deposition calculations were conducted with a currently developed program, termed NANODEP, which allows the variation of numerous input parameters with regard to particle geometry, lung morphometry, and aerosol inhalation.

RESULTS

Generally, alveolar deposition of nanoparticles concerned for this study varies between 0.1% and 12.4% during sitting breathing and between 2.0% and 20.1% during heavy-exercise breathing. Prolate particles (e.g., nanotubes) exhibit a significant increase in deposition, when their aspect ratio is enhanced. In contrast, deposition of oblate particles (e.g., nanoplatelets) is remarkably declined with any reduction of the aspect ratio.

CONCLUSIONS

The study clearly demonstrates that alveolar deposition of nanoparticles represents a topic certainly being of superior interest for physicists and respiratory physicians in future.

Red Blood Cell Dysfunction Induced by High-Fat Diet: Potential Implications for Obesity-Related Atherosclerosis

BACKGROUND

High-fat diet (HFD) promotes endothelial dysfunction and proinflammatory monocyte activation, which contribute to atherosclerosis in obesity. We investigated whether HFD also induces the dysfunction of red blood cells (RBCs), which serve as a reservoir for chemokines via binding to Duffy antigen receptor for chemokines (DARC).

METHODS AND RESULTS

A 60% HFD for 12 weeks, which produced only minor changes in lipid profile in C57/BL6 mice, markedly augmented the levels of monocyte chemoattractant protein-1 bound to RBCs, which in turn stimulated macrophage migration through an endothelial monolayer. Levels of RBC-bound KC were also increased by HFD. These effects of HFD were abolished in DARC(-/-) mice. In RBCs from HFD-fed wild-type and DARC(-/-) mice, levels of membrane cholesterol and phosphatidylserine externalization were increased, fostering RBC-macrophage inflammatory interactions and promoting macrophage phagocytosis in vitro. When labeled ex vivo and injected into wild-type mice, RBCs from HFD-fed mice exhibited ≈3-fold increase in splenic uptake. Finally, RBCs from HFD-fed mice induced increased macrophage adhesion to the endothelium when they were incubated with isolated aortic segments, indicating endothelial activation.

CONCLUSIONS

RBC dysfunction, analogous to endothelial dysfunction, occurs early during diet-induced obesity and may serve as a mediator of atherosclerosis. These findings may have implications for the pathogenesis of atherosclerosis in obesity, a worldwide epidemic.

Abstract A114: Alternatively spliced tissue factor: A new therapeutic target in pancreatic cancer

Background: Pancreatic ductal adenocarcinoma (PDAC) is marked by high expression of Tissue Factor (TF), the trigger of blood coagulation. Alternatively spliced TF (asTF) is a secreted TF form that signals non-proteolytically via β1/β3 integrins. We recently reported that asTF is abundant in PDAC lesions and, when overexpressed in PDAC cells, it promotes tumor growth, metastatic spread, monocyte recruitment, and elevates procoagulant potential of PDAC cells and cell-derived microparticles. In this study, we sought to determine whether i) delayed-onset overexpression of asTF yields a phenotype distinct from that obtained with constitutive overexpression; ii) asTF mechanistically contributes to PDAC cell migration; and iii) antibody-based targeting of asTF slows PDAC progression and/or asTF release into systemic circulation. Methods: Cohorts of nude mice (n=5/cohort) were orthotopically transplanted with grade III human PDAC cells Pt45P1 harboring a doxycycline (Dox)-inducible asTF transgene system (line Pt45P1/asTFi, 5x105 cells/mouse); mice began receiving Dox (2µg/mL) in sucrose at day 1 of the study (“Dox”), day 25 of the study (“late Dox”), or sucrose alone (“no Dox”), and tumor progression was monitored in vivo via SapC-DOPS imaging over 7 wks. PDAC cell migration toward serum was assessed using laminin-coated transwell inserts seeded with Pt45P1/asTFi cells. Plasma samples from mice bearing PDAC tumors were assayed for asTF using a custom sandwich ELISA. asTF-specific rabbit monoclonal antibody Rb1 was co-implanted with Pt45P1 cells, and tumor progression was monitored as above over 5 wks. Tumor specimens were assessed for vessel density (isolectin B4) and monocyte/macrophage infiltration (anti-F4/80 antibody). Results: “Late Dox” mice developed tumors that were comparable in size and vessel density to those in “Dox” mice, yet less infiltrated with macrophages (Dox: 70±22 cells/LPF, late Dox: 51±17 cells/LPF, p=0.009); interestingly, tumor spread was also significantly less pronounced in “late Dox” mice compared to “Dox” mice ([7.52e+7] vs [1.22e+8]P/s/mm2, p=0.01). “Dox” mice also had high levels of asTF in circulation (~1 ng/mL), which did not differ significantly from those in “late Dox” mice. PDAC cell migration assay revealed a ~4 fold increase in the migration of Pt45P1/asTFi cells treated with Dox compared to untreated cells (p&lt;0.001). When cells were co-treated with Dox and inhibitory anti-β1 antibody, migration was inhibited to the levels observed with untreated cells; anti-α6 antibody had a partial effect. Strikingly, migration of Pt45P1/asTFi cells co-treated with Dox and Rb1 was inhibited to the levels observed with untreated cells and/or Dox/anti-β1 antibody co-treated cells; rabbit isotype control IgG had no effect. Pt45P1 cells, when co-implanted with just 100μg of Rb1, grew significantly smaller tumors that were less vascularized and had ~3.5 fold fewer stromal macrophages compared to the cells co-implanted with vehicle (PBS) and/or isotype control IgG (Rb1: avg. wt. 0.835g, 20±9 cells/LPF; PBS: avg. wt. 1.624g, 73±30 cells/LPF; IgG: avg. wt. 1.665g, 66±47 cells/LPF; p&lt;0.005 Rb1 vs PBS/IgG). Mice in the Pt45P1/Rb1 cohort had ~2 fold decrease in the levels of circulating asTF compared to mice in the Pt45P1/PBS and/or isotype IgG cohorts (0.27 ng/mL vs 0.60/0.54 ng/mL; p&lt;0.001). Conclusion: asTF can promote PDAC progression during earlier as well as later stages of the disease. asTF-β1 integrin interactions render PDAC cells more motile, likely via competing with laminin for β1 integrin binding; Rb1 fully inhibits asTF-potentiated PDAC cell migration. When co-implanted with Rb1, Pt45P1 cells grow much smaller tumors with fewer monocytes and blood vessels that release less asTF in the circulation. Thus, antibody-based targeting of asTF may comprise a novel therapeutic strategy to stem PDAC progression.

Citation Format: Dusten Unruh, Xiaoyang Qi, Zhengtao Chu, Robert Sturm, Ryan Keil, Syed Ahmad, Henri H. Versteeg, Vladimir Y. Bogdanov. Alternatively spliced tissue factor: A new therapeutic target in pancreatic cancer. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Innovations in Research and Treatment; May 18-21, 2014; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2015;75(13 Suppl):Abstract nr A114.

Theoretical deposition of carcinogenic particle aggregates in the upper respiratory tract

BACKGROUND

Numerous particles suspended in the atmosphere are composed of smaller particular components that form aggregates with highly irregular shape. Such aggregates, among which dusts and soot are the most prominent examples, may be taken up into the respiratory tract and, in the worst case, initiate a malignant transformation of lung cells.

METHODS

Particle aggregates were theoretically modelled by using small spheres with equal diameters (1 nm) and arranging them randomly. This procedure resulted in the generation of various aggregate shapes (chain-like, loose, compact), for which essential parameters such as dynamic shape factors, χ, and aerodynamic diameters, dae , were computed. Deposition of aggregates consisting of 10, 50, 100, and 1,000 nano-spheres was simulated for the uppermost parts of the human respiratory system (extrathoracic region and airway generation 0 to 4), thereby distinguishing between sitting and light-work breathing as well as between nasal and oral inhalation.

RESULTS

Based upon the modelling results, aggregate deposition in the human respiratory system can be described as a function of (I) aerodynamic diameter; (II) inhaled particle position within the airway system; and (III) breathing conditions. Therefore, highest deposition values were obtained for nano-scale aggregates (<10 nm), whereas larger aggregates exhibited slightly to significantly reduced deposition probabilities. Extrathoracic regions and uppermost bronchi (generations 0 to 1) were marked by most effective particle capture. Any increase of inhaled air volumes and reduction of breathing times resulted in an enhancement of deposition probabilities of larger particles.

CONCLUSIONS

Based on the results derived from this study it may be concluded that small particle aggregates are accumulated in the uppermost compartments of the human respiratory tract, where they may unfold their unwholesome potential. In the case of carcinogenic particles being stored in epithelial cells for a longer time span, malignant transformations starting with the formation of cancerous cells and ending with the growth of a tumour have to be assumed.

Clearance of carbon nanotubes in the human respiratory tract-a theoretical approach

INTRODUCTION

Theoretical knowledge of carbon nanotube clearance in the human respiratory tract represents an essential contribution to the risk assessment of artificial airborne nanomaterials. Thus, single phases of nanotube clearance were simulated with the help of a theoretical model.

METHODS

In this study, clearance of single-walled carbon nanotubes (SWCNT) and multi-walled carbon nanotubes (MWCNT) was simulated by using a validated mathematical approach that includes all clearance mechanisms known hitherto. Fast mucociliary clearance is approximated by a steady-state steady-flow mucus model, whereas slow clearance mechanisms are modeled by definition of related clearance half-times.

RESULTS

Clearance may be subdivided into three phases, including fast bronchial clearance (mucociliary escalator), slow bronchial clearance (particle uptake by airway macrophages, transcytosis), and alveolar clearance (phagocytosis by alveolar macrophages, endocytosis by alveolar epithelium). According to the clearance model used in this study, mucociliary clearance is completed within the first 24 h after exposure, whereas slow bronchial clearance is characterized by a half-time of 5 d. Alveolar clearance is marked by half-times >100 d. As a result of their different deposition patterns, SWCNT and MWCNT show some discrepancies with regard to their clearance insofar as long SWCNT reside significantly longer in the lungs than MWCNT. This circumstance is among other expressed by higher 24-h, 10-d, and 100-d retentions computed for SWCNT compared to MWCNT.

DISCUSSION AND CONCLUSIONS

Due to their partly high residence times in distal lung regions, carbon nanotubes may bear the potential to act as triggers of inflammatory reactions or fibrotic modifications of the lung structure. Further they may also induce malignant transformations of lung cells, resulting in the development of lung tumours.

Theoretical models for the simulation of particle deposition and tracheobronchial clearance in lungs of patients with chronic bronchitis

INTRODUCTION

Based upon theoretical models particle deposition and clearance in human respiratory systems affected by chronic bronchitis can be approximated reliably. As a consequence of those hypothetical results, optimal frame conditions (e.g., inhalation time and volume, particle properties) for inhalation therapies can be determined.

METHODS

Simulation of particle deposition was conducted by modelling a partly or fully obstructed tracheobronchial architecture. Bronchitis-induced reductions of the airway calibres were computed by application of specific scaling factors. Three different scenarios of chronic bronchitis were modelled. Brownian motion, inertial impaction, interception, and gravitational settling were assumed as main deposition forces influencing inhaled particular mass. Tracheobronchial clearance was approximated by application of generation-specific mucus velocities as well as the consideration of a slow bronchial clearance phase, whose half-time varied between 5 and 20 days.

RESULTS

Under different breathing conditions (i.e., sitting and light-work breathing) deposition of submicron and µm-sized particles is significantly enhanced within the bronchial lung region, but also alveolar deposition becomes partly enhanced. By changing the inhalation conditions target sites of therapeutic aerosols may be reached with rather high accuracy. Based on the data of this modified models, particle retention in lung airways of patients suffering from chronic bronchitis may be noticeably prolonged, with 24-hour retention values being increased by up to 50%.

DISCUSSION AND CONCLUSIONS

As exhibited by the results, particle deposition behaviour in lungs affected by chronic bronchitis differs remarkably from that in healthy lungs. These theoretical finds are mostly supported by experimental data. Further, experimental and theoretical deposition results may be used for an estimation of the grade of disease. Tracheobronchial clearance reduces its efficiency with each progress of the disease which increases the probability of bacterial infections in the airways.

Theoretical deposition of nanotubes in the respiratory tract of children and adults

INTRODUCTION

Nanotubes are assumed to contribute to a significant exacerbation of asthma and to enhance the risk of profibrotic effects in lungs being affected by this injury. Therefore, deposition of nanotubes in the lungs of subjects with different ages was subject to a detailed theoretical investigation.

METHODS

Nanoparticle deposition was computed by application of well validated stochastic deposition model, including four main deposition forces (Brownian diffusion, inertial impaction, interception, gravitational settling). Nonspherical particle geometry was considered with the help of the aerodynamic diameter concept. Deposition was calculated for particles with diameters adopting values of 1, 10, and 100 nm as well as aspect ratios of 10, 50, and 100. Lungs of subjects with different ages were generated with the help of scaling factors and allometric functions. Inhalation was uniformly supposed to take place under non-strain conditions (sitting breathing conditions).

RESULTS

Total deposition of nanotubes is significantly increased with proceeding age, with deposition probability being negatively correlated with particle size (diameter and aspect ratio). Whilst extrathoracic deposition is subject to a slight decrease from infants to adults, bronchial/bronchiolar and alveolar depositions are exponentially increased.

DISCUSSION AND CONCLUSIONS

Due to an increase of nanotube deposition with proceeding age infants and children enjoy a certain protection from excessive particle exposure. This circumstance mostly reprieves their lungs from injuries induced by this sort of particles.

Nanotubes in the human respiratory tract - Deposition modeling

Deposition of inhaled single-wall carbon nanotubes (SWCNT) and multi-wall carbon nanotubes (MWCNT) in the respiratory tract was theoretically investigated for various age groups (infants, children, adolescents, and adults). Additionally, possible effects of the inhalative flow rate on nanotube deposition were simulated for adult lungs. Theoretical computations were based on the aerodynamic diameter concept and the assumption of particles being randomly transported through a stochastic (close-to-realistic) lung structure. Deposition of nanotubes was calculated by application of well validated empirical deposition formulae, thereby considering Browian motion, inertial impaction, interception, and sedimentation as main deposition mechanisms acting on the particles. Results of the simulations clearly show that for a given inhalation scenario (sitting breathing) total, bronchial, and acinar nanotube deposition increase with subject's age, whereas extrathoracic deposition is characterized by a decrease from younger to older subjects. According to the data provided by the model, MWCNT, whose aerodynamic diameters exceed those of SWCNT by one order of magnitude, are deposited in specific respiratory compartments to a lower extent than SWCNT. A change of the physical state from sitting to heavy work results in a common decline of bronchial and extrathoracic deposition of nanotubes. Total deposition is slightly increased for SWCNT and moderately decreased for MWCNT, whereas acinar deposition is significantly increased for SWCNT and decreased for MWCNT. Based on the results of this contribution it may be concluded that SWCNT bear a higher potential as health hazards than MWCNT, because they are accumulated in sensitive lung regions with higher doses than MWCNT.

Aerosol bolus dispersion in healthy and asthmatic children-theoretical and experimental results

INTRODUCTION

In the past decades, aerosol bolus inhalation increasingly came into the focus of medical interest due to its potential as a non-invasive technique for the diagnosis of lung diseases. The experimental studies were accompanied by the development of theoretical contributions dealing with aerosol bolus behaviour in healthy and diseased lungs. In this study, bolus dispersion in healthy and asthmatic children is subject to a theoretical approach. Model predictions are validated with related experimental findings.

METHODS

Aerosol bolus transport was simulated by using (I) a stochastic model of the human respiratory tract; (II) appropriate scaling procedures for the generation of healthy and asthmatic lungs of children; and (III) the concept of effective diffusivities (Deff) for the prediction of convective mixing processes in the conducting airways and alveoli. The aerosol injected into the inhalative air stream consisted of monodisperse particles with a diameter of 0.4 µm (ρ =1 g∙cm(-3)). Volumetric lung depth, being a measure for the position of the aerosol bolus within the inspired air stream, was varied from 95 mL (shallow bolus) to 540 mL (deep bolus). Half-width of the inhaled bolus was set to 50 mL.

RESULTS

According to the predictions provided by the model, dispersion of the exhaled aerosol bolus increases exponentially with volumetric lung depth in both asthmatic children and healthy controls. Asthmatics tend to develop higher bolus dispersion than healthy subjects, with significant differences between the two groups being noticeable at low volumetric lung depths (<300 mL). Skewness decreases with increasing volumetric lung depth, whereby respective values calculated for asthmatics exceed those values computed for healthy subjects. Theoretical results correspond very well with experimental findings.

DISCUSSION AND CONCLUSIONS

Results of experimental bolus studies may be approximated by theoretical models with high accuracy. Model predictions confirm the assumption that inhalation of aerosol boluses and dispersion measurements have only a limited diagnostic potential.

Morbid obesity rates continue to rise rapidly in the United States

Clinically severe or morbid obesity (body mass index (BMI) >40 or 50 kg m(-2)) entails far more serious health consequences than moderate obesity for patients, and creates additional challenges for providers. The paper provides time trends for extreme weight categories (BMI >40 and >50 kg m(-2)) until 2010, using data from the Behavioral Risk Factor Surveillance System. Between 2000 and 2010, the prevalence of a BMI >40 kg m(-2) (type III obesity), calculated from self-reported height and weight, increased by 70%, whereas the prevalence of BMI >50 kg m(-2) increased even faster. Although the BMI rates at every point in time are higher among Hispanics and Blacks, there were no significant differences in trends between them and non-Hispanic Whites. The growth rate appears to have slowed down since 2005. Adjusting for self-report biases, we estimate that in 2010 15.5 million adult Americans or 6.6% of the population had an actual BMI >40 kg m(-2). The prevalence of clinically severe obesity continues to be increasing, although less rapidly in more recent years than prior to 2005.

Absolute quantification of prion protein (90-231) using stable isotope-labeled chymotryptic peptide standards in a LC-MRM AQUA workflow

Substantial evidence indicates that the disease-associated conformer of the prion protein (PrP(TSE)) constitutes the etiologic agent in prion diseases. These diseases affect multiple mammalian species. PrP(TSE) has the ability to convert the conformation of the normal prion protein (PrP(C)) into a β-sheet rich form resistant to proteinase K digestion. Common immunological techniques lack the sensitivity to detect PrP(TSE) at subfemtomole levels, whereas animal bioassays, cell culture, and in vitro conversion assays offer higher sensitivity but lack the high-throughput the immunological assays offer. Mass spectrometry is an attractive alternative to the above assays as it offers high-throughput, direct measurement of a protein's signature peptide, often with subfemtomole sensitivities. Although a liquid chromatography-multiple reaction monitoring (LC-MRM) method has been reported for PrP(TSE), the chemical composition and lack of amino acid sequence conservation of the signature peptide may compromise its accuracy and make it difficult to apply to multiple species. Here, we demonstrate that an alternative protease (chymotrypsin) can produce signature peptides suitable for a LC-MRM absolute quantification (AQUA) experiment. The new method offers several advantages, including: (1) a chymotryptic signature peptide lacking chemically active residues (Cys, Met) that can confound assay accuracy; (2) low attomole limits of detection and quantitation (LOD and LOQ); and (3) a signature peptide retaining the same amino acid sequence across most mammals naturally susceptible to prion infection as well as important laboratory models. To the authors' knowledge, this is the first report on the use of a non-tryptic peptide in a LC-MRM AQUA workflow.

Theoretical models of carcinogenic particle deposition and clearance in children's lungs

INTRODUCTION

Deposition and clearance of carcinogenic particles in the lungs of subjects belonging to four different age groups (infants, children, adolescents, and adults) were theoretically investigated. The study is thought to contribute to the improvement of our knowledge concerning the behaviour of inhaled particles in lungs that may be attributed to different stages of development.

METHODS

Particle deposition and clearance were simulated by using a well established stochastic lung model, allowing the generation of nearly realistic scenarios. For the computation of particle deposition all main deposition forces were considered. Additionally, any influences on particle behaviour due to particle geometry were covered by using the aerodynamic diameter concept. Particle clearance was simulated by defining both a fast mucociliary clearance phase and a slow bronchial/alveolar clearance phase, the latter of which is based on previously published models and suggestions.

RESULTS

As clearly provided by the modelling computations, lung deposition of particles with aerodynamic diameters ranging from 1 nm to 10 µm may significantly differ between the studied age groups. Whilst in infants and children most particles are accumulated in the extrathoracic region and in the upper bronchi, in adolescents and adults high percentages of inhaled particular substances may also reach the lower bronchi and alveoli. Although mucus velocities are significantly lower in young subjects compared to the older ones, fast clearance is more efficient in small lungs due to the shorter clearance paths that have to be passed. Slow clearance is commonly characterized by insignificant discrepancies between the age groups.

CONCLUSIONS

From the study presented here it may be concluded that particle behaviour in infants' and children's lungs has to be regarded in a different light with respect to that in adolescents and adults. Although young subjects possess natural mechanisms of protecting their lungs from hazardous aerosols (e.g., expressed by breathing behaviour and lung size), they are much more sensitive to any particle exposure, since particle concentrations per lung tissue area may reach alarming values within a short period of inhalation.

Radioactivity and lung cancer-mathematical models of radionuclide deposition in the human lungs

The human respiratory tract is regarded as pathway for radionuclides and other hazardous airborne materials to enter the body. Radioactive particles inhaled and deposited in the lungs cause an irradiation of bronchial/alveolar tissues. At the worst, this results in a malignant cellular transformation and, as a consequence of that, the development of lung cancer. In general, naturally occurring radionuclides (e.g., (222)Rn, (40)K) are attached to so-called carrier aerosols. The aerodynamic diameters of such radioactively labeled particles generally vary between several nanometers (ultrafine particles) and few micrometers, whereby highest particle fractions adopt sizes around 100 nm. Theoretical simulations of radioactive particle deposition in the human lungs were based on a stochastic lung geometry and a particle transport/deposition model using the random-walk algorithm. Further a polydisperse carrier aerosol (diameter: 1 nm-10 µm, ρ ≈ 1 g cm(-3)) with irregularly shaped particles and the effect of breathing characteristics and certain respiratory parameters on the transport of radioactive particles to bronchial/alveolar tissues were considered. As clearly shown by the results of deposition modeling, distribution patterns of radiation doses mainly depend on the size of the carrier aerosol. Ultrafine (< 10 nm) and large (> 2 µm) aerosol particles are preferentially deposited in the extrathoracic and upper bronchial region, whereas aerosol particles with intermediate size (10 nm-2 µm) may penetrate to deeper lung regions, causing an enhanced damage of the alveolar tissue by the attached radionuclides.

An advanced stochastic model for mucociliary particle clearance in cystic fibrosis lungs

BACKGROUND

A mathematical model describing mucociliary clearance in cystic fibrosis (CF) patients and its development with progressing course of the disease was developed. The approach should support the prediction of the disease state on the basis of measured bronchial clearance efficiencies.

METHODS

The approach is based on the assumption of a steady-state steady-flow mucus transport through the tracheobronchial tree which enables the determination of airway generation-specific mucus velocities by using a measured tracheal mucus velocity and a realistic morphometric dataset of the human lung. Architecture of the tracheobronchial tree was approximated by a stochastic model, reflecting the intra-subject variability of geometric parameters within a given lung generation.

RESULTS

As predicted by the appropriately validated mathematical approach, mucociliary clearance efficiency in CF patients is partly significantly decreased with respect to healthy controls. 24-h retention of patients with mild CF (FEV(1) >70% of predicted) is reduced by 10% compared to healthy subjects, whilst 24-h retention of patients with moderate to severe CF (FEV(1) <70% of predicted) differs by 25% from that of the healthy controls. These discrepancies are further enhanced with continuation of the clearance process.

CONCLUSIONS

The theoretical results lead to the conclusion that CF patients have a higher risk of inhaled particle accumulation and related particle overload in specific lung compartments than healthy subjects.

Is there a robust relationship between neighbourhood food environment and childhood obesity in the USA?

OBJECTIVES

To examine the robustness of the relationship between neighbourhood food environment and youth body mass index (BMI) percentile using alternative measures of food environment and model specifications.

STUDY DESIGN

Observational study using individual-level longitudinal survey data of children in fifth and eighth grades merged with food outlet data based on student residential census tracts.

METHODS

The relationship between food environment and BMI was examined with two individual outcomes (BMI percentile in eighth grade and change in BMI percentile from fifth to eighth grade) and three alternative measures of food environment (per-capita counts of a particular outlet type, food environment indices, and indicators for specific combinations of outlet types).

RESULTS

No consistent evidence was found across measures (counts of a particular type of food outlet per population, food environment indices, and indicators for the presence of specific combinations of types of food stores) and outcomes to support the hypothesis that improved access to large supermarkets results in lower youth BMI; or that greater exposure to fast food restaurants, convenience stores and small food stores increases BMI.

CONCLUSIONS

To the extent that there is an association between food environment and youth BMI, the existence of more types of food outlets in an area, including supermarkets, is associated with higher BMI.

Nonproteolytic properties of murine alternatively spliced tissue factor: implications for integrin-mediated signaling in murine models

This study was performed to determine whether murine alternatively spliced tissue factor (masTF) acts analogously to human alternatively spliced tissue factor (hasTF) in promoting neovascularization via integrin ligation. Immunohistochemical evaluation of a spontaneous murine pancreatic ductal adenocarcinoma model revealed increased levels of masTF and murine full-length tissue factor (mflTF) in tumor lesions compared with benign pancreas; furthermore, masTF colocalized with mflTF in spontaneous aortic plaques of Ldlr(-/-) mice, indicating that masTF is likely involved in atherogenesis and tumorigenesis. Recombinant masTF was used to perform in vitro and ex vivo studies examining its integrin-mediated biologic activity. Murine endothelial cells (ECs) rapidly adhered to masTF in a β3-dependent fashion. Using adult and embryonic murine ECs, masTF potentiated cell migration in transwell assays. Scratch assays were performed using murine and primary human ECs; the effects of masTF and hasTF were comparable in murine ECs, but in human ECs, the effects of hasTF were more pronounced. In aortic sprouting assays, the potency of masTF-triggered vessel growth was undistinguishable from that observed with hasTF. The proangiogenic effects of masTF were found to be Ccl2-mediated, yet independent of vascular endothelial growth factor. In murine ECs, masTF and hasTF upregulated genes involved in inflammatory responses; murine and human ECs stimulated with masTF and hasTF exhibited increased interaction with murine monocytic cells under orbital shear. We propose that masTF is a functional homolog of hasTF, exerting some of its key effects via β3 integrins. Our findings have implications for the development of murine models to examine the interplay between blood coagulation, atherosclerosis and cancer.

Morphology and ultrastructure of the accessory glands in the female genital tract of the house cricket, Acheta domesticus

The accessory glands in the genital tract of female Acheta domesticus L. (Orthoptera: Gryllidae) were investigated in detail. The glands are situated within the 7(th) and 8(th) abdominal segment and lead to the genital chamber lateral to the terminal papilla of the ductus receptaculi. The shape of the gland is characterized by a complex system of tubules, including numerous ramifications. The gland's size ranges from 2 to 4 mm. The epithelium is constructed according to a simple scheme and consists of a cuticular intima at the luminal side, one layer of gland cells, and a basallamina at the outermost side. The observed morphology of the accessory glands widely corresponds with that in other cricket species (e.g., Teleogryllus commodus). This is also true for the structure of a single gland cell, which can be subdivided into a basal part with nucleus and intracellular cisternae, as well as an apical part with all those compartments responsible for the production of the secretion. The secretion itself may be classified as lipophilic and is produced for the first time 4 to 6 days after the imaginai moult. Several endogenic functions of the secretion are discussed (lubricant for oviposition, support for introducing the tube of the spermatophore into the ductus receptaculi, etc.).

Mass spectrometry imaging for drugs and metabolites

Mass spectrometric imaging (MSI) is a powerful analytical technique that provides two- and three-dimensional spatial maps of multiple compounds in a single experiment. This technique has been routinely applied to protein, peptide, and lipid molecules with much less research reporting small molecule distributions, especially pharmaceutical drugs. This review's main focus is to provide readers with an up-to-date description of the substrates and compounds that have been analyzed for drug and metabolite composition using MSI technology. Additionally, ionization techniques, sample preparation, and instrumentation developments are discussed.

Theoretical models for dynamic shape factors and lung deposition of small particle aggregates originating from combustion processes

A theoretical model was developed which allows the generation of irregularly shaped aggregate particles due to the stepwise joining of spherical components with variable diameters. The mathematical approach is mainly thought to act as a supporting tool for the simulation of the transport and deposition behaviour of combustion aerosols in the atmosphere and the human respiratory tract. In combination with aggregate construction essential particle parameters (dynamic shape factor χ, aerodynamic diameter d(ae)) are computed using the model. As a main result of aggregate generation, an increasing particle size, expressed by an increasing number of spherical components, leads to an enhancement of χ and d(ae), whereby values of the first parameter range from 2 to 70. Deposition of small aggregates (sizes between 2 and 200nm) in the human respiratory tract is commonly marked by high rates of bronchial particle accumulation (40-60%) and declined rates of extrathoracic (20-30%) and alveolar accumulation (2-15%). Concerning aggregate deposition by airway generation, increased cluster size causes a significant decrease of particle accumulation in the proximal airways, whilst accumulation in the intermediate to distal airways is dramatically enhanced. The model was validated using experimental deposition data of tobacco smoke. An excellent correspondence between experimental and theoretical results was found.

A theoretical approach to the deposition and clearance of fibers with variable size in the human respiratory tract

In the study presented here, a mathematical approach for the deposition and clearance of rigid and chemically stable fibers in the human respiratory tract (HRT) is described in detail. For the simulation of fiber transport and deposition in lung airways an advanced concept of the aerodynamic diameter is applied to a stochastic lung model with individual particle trajectories computed according to a random walk algorithm. Interception of fibrous material at airway bifurcations is considered by implementation of correction factors obtained from previously published numerical approaches to fiber deposition in short bronchial sequences. Fiber clearance is simulated on the basis of a multicompartment model, within which separate clearance scenarios are assumed for the alveolar, bronchiolar, and bronchial lung region and evacuation of fibrous material commonly takes place via the airway and extrathoracic path to the gastrointestinal tract (GIT) or via the transepithelial path to the lymph nodes and blood vessels. Deposition of fibrous particles in the HRT is controlled by the fiber aspect ratio beta in as much as particles with diameters <0.1 microm deposit less effectively with increasing beta, while larger particles exhibit a positive correlation between their deposition efficiencies and beta. A change from sitting to light-work breathing conditions causes only insignificant modifications of total fiber deposition in the HRT, whereas alveolar and, above all, tubular deposition of fibrous particles with a diameter >or=0.1 microm are affected remarkably. For these particles enhancement of the inhalative flow rate results in an increase of the extrathoracic and bronchial deposition fractions. Concerning the clearance of fibers from the HRT, 24-h retention is noticeably influenced by beta and, not less important, by the preferential deposition sites of the simulated particles. The significance of beta with respect to particle size may be regarded as similar to that determined for the deposition scenarios, while breathing conditions do not have a valuable effect on clearance.

LONG-TERM CLEARANCE FROM SMALL AIRWAYS IN PATIENTS WITH CHRONIC BRONCHITIS: EXPERIMENTAL AND THEORETICAL DATA

Long-term clearance (21 days) from small airways was studied in 9 patients with chronic bronchitis (CB), 65 +/- 10 (mean +/- SD) years, and was compared to 15 age-matched healthy subjects of 67 +/- 7 (mean +/- SD) years. Six of the CB patients were studied twice. All subjects inhaled monodisperse 6 microm Teflon particles labelled with 111In with an extremely slow inhalation flow, 0.05 L/s. With this inhalation technique, particles are deposited mainly in the small conducting airways. Lung retention was measured at 0 and 24 hours, and at 7, 14, and 21 days after inhalation. Lung retention at 24 hours (% of deposition) was highly reproducible for the CB patients, studied twice, but it was not significantly different from that found for healthy subjects and, furthermore, not related to airway resistance (Raw), nor FEV1% predicted. Both healthy subjects and CB patients showed significant clearance in the period between 24 hours and day 21. The mean retention were higher (P<.001) in CB patients, 90%, 89%, 87% of 24 hours retention at 7, 14, and 21 days, compared to 80%, 76%, 71% of 24 hours retention at 7, 14, and 21 days measurements for healthy subjects. Clearance after 24 hours (retention at 21 days) was significantly related to FEV1% predicted, but not Raw. Reduced FEV1% predicted values was associated with slower clearance rates. Model calculations were performed to estimate intrapulmonary deposition patterns. A limited effect was shown for airway dimension and uneven ventilation. The differences between healthy and CB patients were, however, limited. It is not possible to conclude whether the difference in clearance after 24 hours is an effect of change in regional deposition, or slower small airway clearance in diseased airways. This technique to target the smallest ciliated airways, using an extremely slow inhalation flow, provides new possibilities to investigate smallest airway function and drug delivery that merits further investigations.

Semi-empirical stochastic model of aerosol bolus dispersion in the human lung

Aerosol bolus dispersion, that is, the broadening of an inhaled narrow aerosol bolus upon exhalation, was simulated by Monte Carlo methods using a stochastic, asymmetric morphometric model of the human lung. Physical mechanisms considered to contribute to bolus dispersion were (1) axial diffusion in conductive airways, approximated by effective diffusivities, (2) convective mixing at airway bifurcation sites, (3) differences in inspiratory and expiratory velocity profiles, (4) mixing with residual air in alveoli, and (5) inhomogeneous ventilation of the lung lobes due to asymmetric flow spitting at bifurcations and asymmetric and asynchronous filling of the five lung lobes. Theoretical predictions of the bolus dispersion model were compared to experimental data for 79 healthy volunteers, which provide detailed information on statistical bolus parameters (half-width, standard deviation, skewness, and mode shift) and total bolus deposition as a function of the depth of bolus penetration into the airway system. Predicted bolus dispersion and deposition data show excellent agreement with the published experimental data, suggesting that axial diffusion in conductive airways and convective mixing in alveoli, resulting in irreversible particle transport, are the major determinants of bolus dispersion. The variability and asymmetry of the branching airway network, leading to asymmetric flow splitting at airway bifurcations, greatly enhances the effect of irreversibility and the resulting dispersion of the inhaled bolus.