Oral Contraceptive Pills Increase Circulating 25-Hydroxy-Vitamin D Concentrations in Women Who Are Lactating.

OBJECTIVE: This article aims to determine the association between maternal 25-hydroxy-vitamin D [25(OH)D] status and intake of hormonal oral contraceptive pills (OCPs) in women who are lactating. STUDY DESIGN: Women who were exclusively breastfeeding participated in a randomized controlled trial assessing vitamin D supplementation at 400, 2,400, or 6,400 international unit (IU)/d from 1 month through 7 months postpartum. This observational, secondary analysis assessed whether OCPs were associated with maternal 25(OH)D concentrations in women who are lactating. Multivariate regression models were used to predict 25(OH)D concentrations and create parameter estimates for each variable. RESULTS: In a bivariate analysis, the use of OCPs at 4 months was associated with increased serum 25(OH)D (p = 0.02). OCPs' use at 7 months was associated with a higher trend in 25(OH)D, but this finding was not statistically significant (p = 0.1). In a multivariate regression model at 4 months, independent positive predictors of 25(OH)D concentrations were the use of OCPs (p = 0.03) and treatment with vitamin D at 6,400 IU/d (p ≤ 0.0001). Negative predictors were Black (p = 0.001) and Hispanic (p = 0.0001) race and ethnicity, and body mass index (BMI) greater than 30 (p = 0.0002). The same pattern occurred at 7 months, with more southern latitude as a positive independent predictor (p = 0.04) of 25(OH)D concentration. CONCLUSION: The use of OCPs was associated with greater 25(OH)D in women who are lactating. Additionally, treatment with vitamin D at 6,400 IU/d and southern latitude was associated with greater 25(OH)D in women who are lactating. Black and Hispanic race and ethnicity, and BMI greater than 30, were independently associated with lower 25(OH)D in women who are lactating. KEY POINTS: · The association of OCP with serum 25(OH)D concentrations during postpartum lactation is unknown.. · OCPs' use was associated with higher 25(OH)D concentrations in postpartum women who are lactating.. · Treatment with vitamin D and southern latitude was associated with greater 25(OH)D in women who are lactating.. · Black and Hispanic, and BMI > 30 were associated with lower 25(OH)D in women who are lactating.. · Practitioners can counsel women who are lactating on OCPs' use and the positive effects on their 25(OH)D status..

Radon Flux Measurement System.

ABSTRACT: Disposal of naturally occurring radioactive material (NORM) and technologically enhanced naturally occurring radioactive material (TENORM) waste in the State of Oregon is prohibited unless it can be demonstrated that the material is nonradioactive as defined by its radionuclide content and potential for emission into the environment. It was determined that a radon flux on the surface of the waste no greater than 0.37 Bq m -2 s -1 would meet this requirement. This article provides a method to estimate the radon flux through indirect measurement of the radon mass exhalation rate. It describes a device that consists of a radon accumulation chamber coupled with a continuous radon monitor and software to process the results and calculate the radon mass exhalation rate and radon flux for an unknown sample of approximately 500 g. The chamber system was tested with a uranium ore sample.

Caring for Each Other: A Resident-Led Peer Debriefing Skills Workshop.

Background: Inadequate time and space to process critical incidents contribute to burnout. Residents do not regularly participate in emotional debriefs. An institutional needs assessment revealed only 11% of surveyed pediatrics and combined medicine-pediatrics residents had participated in a debrief. Objective: The primary objective was to increase resident comfort in participation in peer debriefs after critical incidents from 30% to 50% with implementation of a resident-led peer debriefing skills workshop. Secondary objectives included increasing resident likelihood of leading debriefs and comfort in identifying symptoms of emotional distress. Methods: Internal medicine, pediatrics, and medicine-pediatrics residents were surveyed for baseline participation in debriefs and comfort in leading peer debriefs. Two senior residents became trained debrief facilitators and led a 50-minute peer debriefing skills workshop for co-residents. Pre- and post-workshop surveys assessed participant comfort in and likelihood of leading peer debriefs. Surveys distributed 6 months post-workshop assessed resident debrief participation. We implemented the Model for Improvement from 2019 to 2022. Results: Forty-six (77%) and 44 (73%) of the 60 participants completed the pre- and post-workshop surveys. Post-workshop, residents' reported comfort in leading debriefs increased from 30% to 91%. The likelihood of leading a debrief increased from 51% to 91%. Ninety-five percent (42 of 44) agreed that formal training in debriefing is beneficial. Almost 50% (24 of 52) of surveyed residents preferred to debrief with a peer. Six months post-workshop, 22% (15 of 68) of surveyed residents had led a peer debrief. Conclusions: Many residents prefer to debrief with a peer after critical incidents that cause emotional distress. Resident-led workshops can improve resident comfort in peer debriefing.

Redesigning Care of Hospitalized Young Adults With Chronic Childhood-Onset Disease.

Background Young adults with chronic childhood-onset disease (CCOD) are routinely admitted to internal medicine hospitalist services, yet most lack transition preparation to adult care. Providers and patients feel the strain of admissions to adult services in part due to their medical and social complexity. Methods We performed a descriptive study of a care redesign project for young adults with CCOD hospitalized at a large, tertiary care academic hospital. We describe the process of implementation of the Med-Peds (MP) service line and characterize patients cared for by the service. We measured and analyzed patient demographics, process implementation, healthcare screening, and healthcare utilization data. Results During the 16 months of the study period, 254 patients were cared for by the MP service line, accounting for 385 hospitalizations. The most common CCODs were sickle cell disease (22.4%) and type 1 diabetes (14.6%). The majority (76%) of patients completed transition readiness assessment, and 38.6% completed social determinant of health (SDH) screening during their admission. Patients had high prevalence of SDH with 66.7% having an unmet social need. The average length of stay was 6.6 days and the average 30-day readmission rate was 20.0%. Conclusions There is opportunity to redesign the inpatient care of young adult patients with CCOD. The MP service line is a care model that can be integrated into existing hospital medicine teams with MP physicians. Hospitals should consider redesigning care for young adults with CCOD to meet the transitional and social needs unique to this patient population.

Investigation of Melissococcus plutonius isolates from 3 outbreaks of European foulbrood disease in commercial beekeeping operations in western Canada.

European foulbrood (EFB) disease is an economically important bacterial disease of honey bee larvae caused by enteric infection with Melissococcus plutonius. In this study, we investigated 3 clinical outbreaks of EFB disease in commercial beekeeping operations in western Canada in the summer of 2020 and characterized the Melissococcus plutonius isolates cultured from these outbreaks according to genetic multi-locus sequence type and i n vitro larval pathogenicity. We isolated M. plutonius sequence type 19 from EFB outbreaks in British Columbia and Alberta, and a novel M. plutonius sequence type 36 from an EFB outbreak in Saskatchewan. In vitro larval infection with each M. plutonius isolate was associated with decreased larval survival in vitro by 58.3 to 70.8% (P < 0.001) compared to non-infected controls. Further elucidation of mechanisms of virulence of M. plutonius, paired with epidemiologic investigation, is imperative to improve EFB management strategies and mitigate risks of EFB outbreaks in western Canada.

Enquête sur des isolats de Melissococcus plutonius provenant de trois éclosions de loque e uropéenne dans des exploitations apicoles commerciales de l'Ouest canadien. La loque européenne (EFB) est une maladie bactérienne économiquement importante des larves d'abeilles mellifères causée par une infection entérique par Melissococcus plutonius. Dans cette étude, nous avons enquêté sur trois éclosions cliniques de la maladie EFB dans des exploitations apicoles commerciales dans l'ouest du Canada à l'été 2020 et caractérisé les isolats de Melissococcus plutonius cultivés à partir de ces éclosions selon le typage génomique multilocus et la pathogénicité larvaire in vitro. Nous avons isolé le type de séquence 19 de M. plutonius des éclosions d'EFB en Colombie-Britannique et en Alberta, et une nouvelle séquence de type 36 de M. plutonius d'une éclosion d'EFB en Saskatchewan. L'infection larvaire in vitro avec chaque isolat de M. plutonius était associée à une diminution de la survie larvaire in vitro de 58,3 à 70,8 % (P < 0,001) par rapport aux témoins non infectés. Une élucidation plus poussée des mécanismes de virulence de M. plutonius, associée à une enquête épidémiologique, est impérative pour améliorer les stratégies de gestion de l'EFB et atténuer les risques d'épidémies d'EFB dans l'Ouest canadien.(Traduit par Dr Serge Messier).

Establishment of apiary-level risk of American foulbrood through the detection of Paenibacillus larvae spores in pooled, extracted honey in Saskatchewan.

Paenibacillus larvae, the causative agent of American foulbrood (AFB), produces spores that may be detectable within honey. We analyzed the spore content of pooled, extracted honey from 52 large-scale (L) and 64 small-scale (S) Saskatchewan beekeepers over a two-year period (2019-2020). Our objectives were: (i) establish reliable prognostic reference ranges for spore concentrations in extracted honey to determine future AFB risk at the apiary level; (ii) identify management practices as targets for mitigation of risk. P. larvae spores were detected in 753 of 1476 samples (51%). Beekeepers were stratified into low (< 2 spores/gram), moderate (2- < 100 spores/gram), and high (≥ 100 spores/gram) risk categories. Of forty-nine L beekeepers sampled in 2019, those that reported AFB in 2020 included 0/26 low, 3/18 moderate, and 3/5 high risk. Of twenty-seven L beekeepers sampled in 2020, those that reported AFB in 2021 included 0/11 low, 2/14 moderate, and 1/2 high risk. Predictive modelling included indoor overwintering of hives, purchase of used equipment, movement of honey-producing colonies between apiaries, beekeeper demographic, and antimicrobial use as risk category predictors. Saskatchewan beekeepers with fewer than 2 spores/gram in extracted honey that avoid high risk activities may be considered at low risk of AFB the following year.

Comparison of individual hive and apiary-level sample types for spores of Paenibacillus larvae in Saskatchewan honey bee operations.

Three commercial honey bee operations in Saskatchewan, Canada, with outbreaks of American foulbrood (AFB) and recent or ongoing metaphylactic antibiotic use were intensively sampled to detect spores of Paenibacillus larvae during the summer of 2019. Here, we compared spore concentrations in different sample types within individual hives, assessed the surrogacy potential of honey collected from honey supers in place of brood chamber honey or adult bees within hives, and evaluated the ability of pooled, extracted honey to predict the degree of spore contamination identified through individual hive testing. Samples of honey and bees from hives within apiaries with a recent, confirmed case of AFB in a single hive (index apiaries) and apiaries without clinical evidence of AFB (unaffected apiaries), as well as pooled, apiary-level honey samples from end-of-season extraction, were collected and cultured to detect and enumerate spores. Only a few hives were heavily contaminated by spores in any given apiary. All operations were different from one another with regard to both the overall degree of spore contamination across apiaries and the distribution of spores between index apiaries and unaffected apiaries. Within operations, individual hive spore concentrations in unaffected apiaries were significantly different from index apiaries in the brood chamber (BC) honey, honey super (HS) honey, and BC bees of one of three operations. Across all operations, BC honey was best for discriminating index apiaries from unaffected apiaries (p = 0.001), followed by HS honey (p = 0.06), and BC bees (p = 0.398). HS honey positively correlated with both BC honey (rs = 0.76, p < 0.0001) and bees (rs = 0.50, p < 0.0001) and may be useful as a surrogate for either. Spore concentrations in pooled, extracted honey seem to have predictive potential for overall spore contamination within each operation and may have prognostic value in assessing the risk of future AFB outbreaks at the apiary (or operation) level.

Mitogen-activated protein kinase-activated protein kinase-2 (MK2) and its role in cell survival, inflammatory signaling, and migration in promoting cancer.

Cancer and the immune system share an intimate relationship. Chronic inflammation increases the risk of cancer occurrence and can also drive inflammatory mediators into the tumor microenvironment enhancing tumor growth and survival. The p38 MAPK pathway is activated both acutely and chronically by stress, inflammatory chemokines, chronic inflammatory conditions, and cancer. These properties have led to extensive efforts to find effective drugs targeting p38, which have been unsuccessful. The immediate downstream serine/threonine kinase and substrate of p38 MAPK, mitogen-activated-protein-kinase-activated-protein-kinase-2 (MK2) protects cells against stressors by regulating the DNA damage response, transcription, protein and messenger RNA stability, and motility. The phosphorylation of downstream substrates by MK2 increases inflammatory cytokine production, drives an immune response, and contributes to wound healing. By binding directly to p38 MAPK, MK2 is responsible for the export of p38 MAPK from the nucleus which gives MK2 properties that make it unique among the large number of p38 MAPK substrates. Many of the substrates of both p38 MAPK and MK2 are separated between the cytosol and nucleus and interfering with MK2 and altering this intracellular translocation has implications for the actions of both p38 MAPK and MK2. The inhibition of MK2 has shown promise in combination with both chemotherapy and radiotherapy as a method for controlling cancer growth and metastasis in a variety of cancers. Whereas the current data are encouraging the field requires the development of selective and well tolerated drugs to target MK2 and a better understanding of its effects for effective clinical use.

Testicular Changes of Honey Bee Drones, Apis mellifera (Hymenoptera: Apidae), During Sexual Maturation.

The normal developmental anatomy and histology of the reproductive tract of the honey bee drone, Apis mellifera (Linnaeus, 1758), has been well documented. The post-emergence maturation changes of the accessory glands are likewise well understood, but the normal histological changes of the testicle undergoing physiologic atrophy are not well characterized. To address this knowledge gap, herein we describe the anatomy and sequential histological stages of normal testicular atrophy of drones sampled daily from emergence to sexual maturity in the spring (June) and early summer (July). Testicular histological changes during maturation are characterized by the following stages: I) conclusion of spermiogenesis; II) evacuation of spermatodesms from tubular lumens; III) progressive follicular cell atrophy, and IV) complete atrophy and collapse of testicular parenchyma. Tubular changes occur in a basilar to apical direction where segments closer to the vas deferens are histologically more mature than corresponding apical segments. In addition, the rate of testicular maturation was found to change with seasonal progression. This description of physiologic testicular atrophy should be useful for future studies investigating potential pathological effects of stressors on drone testes during sexual maturation.

Morphometric, metabolic, and inflammatory markers across a cohort of client-owned horses and ponies on the insulin dysregulation spectrum.

In human metabolic syndrome and type II diabetes, methylglyoxal (MG), D-lactate, and several cytokines have been recognized as biomarkers of important metabolic and inflammatory processes. Equine metabolic syndrome (EMS) shares many similarities with these human counterparts. The objectives of this cross-sectional study were to compare body condition score (BCS), cresty neck score (CNS), resting insulin, MG, D-lactate, L-lactate, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and monocyte chemoattractant protein-1 (MCP-1) between horses with and without insulin dysregulation, as classified via combined glucose and insulin test (CGIT). 32 client-owned horses were included. History and morphometric data such as BCS and CNS were recorded. Subjects with abnormalities on physical examination or CBC, elevated ACTH or incomplete information were excluded. Baseline serum or plasma concentrations of biomarkers were tested via commercial ELISA or colorimetric assays. Characteristics of insulin dysregulated and insulin sensitive horses were compared by univariate analysis and forward logistic regression. 12 (38%) of the 32 horses were classified as insulin dysregulated. No significant difference between the 2 groups was found for age, BCS, baseline glucose, triglycerides, MG, D-lactate, L-lactate, TNF-α, IL-6, and MCP-1. Baseline insulin was significantly associated with insulin dysregulation in univariate analysis (P = 0.02), but not in the final model. Horses with CNS ≥ 3 had 11.3 times higher odds of having insulin dysregulation (OR 11.3, 95% C.I. 2.04 - 63.08, P = 0.006). In this population, horses with mild-moderate signs of EMS presented similar metabolic and inflammatory profiles to non-insulin dysregulated controls.

Dexamethasone Alters Tracheal Aspirate T-Cell Cytokine Production in Ventilated Preterm Infants.

Postnatal corticosteroids improve respiratory status and facilitate respiratory support weaning in preterm infants with bronchopulmonary dysplasia (BPD). Older literature describes characteristic cytokine profiles in tracheal aspirates (TA) of BPD patients which are altered with corticosteroids. Corticosteroids also influence peripheral blood T-cell presence. However, little is known regarding TA T-cell phenotype and cytokine production before or after exogenous corticosteroids. We hypothesized that postnatal dexamethasone alters the TA T-cell cytokine profiles of preterm infants. TA samples were collected from 14 infants born from 23 0/7 to 28 6/7 weeks who were mechanically ventilated for at least 14 days. Samples were collected up to 72 h before a ten-day dexamethasone course and again 1 to 3 calendar days after dexamethasone initiation. The primary outcome was change in T cell populations present in TA and their intracellular cytokine profile after dexamethasone treatment, ascertained via flow cytometry. Following dexamethasone treatment, there were significant decreases in respiratory severity score (RSS), percent CD4+IL-6+ cells, CD8+IL-6+ cells, CXCR3+IL-6+ cells, and CXCR3+IL-2+ cells and total intracellular IFN-γ in TA. RSS significantly correlated with TA percent CD4+IL-6+ cells. To our knowledge, this is the first study demonstrating that dexamethasone reduced T-cell IL-6 and this reduction was associated with improved RSS in pre-term infants with evolving BPD.

Reproductive fitness of honey bee queens exposed to thiamethoxam during development.

The productivity and survival of honey bee (Apis mellifera) colonies depend on queen bee health. Colony-level neonicotinoid exposure has negative effects on reproductive fitness of honey bee queens. However, it is unclear if the observed effects are a direct outcome of neonicotinoid toxicity or result from suboptimal care of developing queens by exposed workers. The aim of this study was to evaluate larval survival, reproductive fitness, and histopathology of honey bee queens exposed to incremental doses (0, 5, 50 ng) of the neonicotinoid thiamethoxam (THI) applied directly to individual late larvae (7 days post-oviposition) of queens. The 5 ng dose represents a calculated high environmental level of exposure for honey bee queen larvae. Morphometric evaluation revealed that the total area of mandibular gland epithelium in queens exposed to 5 and 50 ng THI was reduced by 14% (P = .12) and 25% (P = .001), respectively. Decreased mandibular gland size may alter pheromone production, which could in part explain previously observed negative effects of THI on the reproductive fitness of queens. We also found that late larval exposure to THI reduced larval and pupal survival and decreased sperm viability in mated queens. These changes may interfere with queen development and reproductive longevity.

Integrating Regional Frameworks and Local Variability for Riverine Bioassessment.

Regional frameworks enable bioassessment methods to detect anthropogenic effects on ecosystems amid natural variability. Conventional approaches to regionalization have used coarse geographical frameworks to separate sites similar in their ecological (ecoregion) or faunal (basin) characteristics. Expectations for individual streams are then adjusted for within-region variability in local environmental characteristics. Integrating regional frameworks and local variability may improve the sensitivity and performance of bioassessments. In this study, we used a biologically-informed stream classification to develop an integrated regional framework for bioassessment considering the effects of ecoregion, basin, and local environmental variables on wadeable stream fish communities of South Carolina, USA. Our integrated framework was compared against conventional regional frameworks indexing ecoregions or basins alone. Frameworks were evaluated by their ability to (1) efficiently partition community variation and (2) allow for the detection of anthropogenic effects on fish communities. We found an integrated framework better described natural variability in stream fish communities. In addition, we found highly regional relationships between fish metrics and anthropogenic disturbance among frameworks, suggesting appropriate bioassessment metrics will differ across regions in our study area. Differences in community response to disturbance among frameworks emphasize the importance of testing metrics for their hypothesized sensitivity before using them in bioassessment. This study ultimately supports the integration of regional frameworks across spatial scales to classify streams for bioassessment, and provides an analytical framework from which to evaluate biotic variation and metric utility in the context of bioassessment.

Clinical and laboratory impact of concomitant syphilis infection during acute HIV.

INTRODUCTION: Cognitive impairment has been reported in people living with HIV-1 (PLWH) with prior syphilis, while PLWH who present with incident syphilis have reduced blood CD4 T-lymphocyte and elevated HIV-1 RNA levels. However, the clinical, virological and neurocognitive effects of syphilis during acute HIV-1 (AHI) remain unknown. METHODS: Pre-antiretroviral therapy laboratory outcomes and neurocognitive performance in a four-test battery in the SEARCH10/RV254 AHI cohort were compared according to syphilis status, determined by serum Treponema pallidum haemagglutination (TPHA), Venereal Disease Research Laboratory (VDRL) and syphilis treatment history. Impaired cognitive performance was defined as having z-scores ≤ -1 in at least two tests or ≤ -2 in at least one test. RESULTS: Out of 595 AHI participants (97% male, median age of 26 years and estimated duration of HIV-1 infection of 19 days), 119 (20%) had history of syphilis (TPHA-positive), of whom 51 (9%) had untreated syphilis (TPHA-positive/VDRL-positive/without prior treatment). Compared with those without syphilis (TPHA-negative), individuals with untreated syphilis had higher CD8 T-lymphocyte levels but not higher plasma HIV-1 RNA or lower CD4 T-lymphocyte levels. Taking into account estimated duration of HIV-1 infection (P < 0.001), and later Fiebig stages (III-V) (P < 0.001), those with untreated syphilis had higher CD8 T-lymphocyte levels (P = 0.049). Individuals with any syphilis (TPHA-positive), but not untreated syphilis, had higher odds of impaired cognitive performance than those without (P = 0.002). CONCLUSIONS: During AHI, individuals with any history of syphilis (TPHA-positive) had poorer cognitive performance than those without syphilis. However, syphilis was not associated with worsened HIV disease measures as described in chronic infection.

Incorporating Network Connectivity into Stream Classification Frameworks.

Stream classification frameworks are important tools for conserving aquatic resources. Yet despite their utility, most classification frameworks have not incorporated network connectivity. We developed and compared three biologically informed stream classification frameworks considering the effects of variables indexing local habitat and/or connectivity on stream fish communities. The first framework classified streams according to local environmental variables largely following the precedent set by previous stream classifications. The second framework classified streams according solely to network connectivity variables, while the third framework considered both local and connectivity variables. Using fish community data from 291 wadeable streams in South Carolina, USA, we used conditional inference tree analyses to identify either seven or eight discrete types of wadeable streams within each framework. Classifications were evaluated on their ability to describe community composition at a subset of sites not used in model training, and canonical correspondence analysis suggested that each framework performed similarly in describing overall community variation, with about 19% of variation explained. After accounting for the effects of biogeography and land use in our analytical approach, each classification explained a substantially higher amount of community variation with 46% of variation explained by our connectivity-informed classification and 42% explained by our locally informed classification. Classifications differed in their ability to describe elements of community structure; a classification incorporating connectivity predicted species richness better than the one that did not. This study ultimately addresses an important knowledge gap in the classification literature while providing broader implications for the conservation of aquatic organisms and their habitats.

Estimation of absorbed radiation doses to skin and S-values for organs at risk due to nasal administration of PET agents using Monte Carlo simulations.

PURPOSE: The intranasal (IN) administration of radiopharmaceuticals is of interest in being a viable route for the delivery of radiopharmaceuticals that do not ordinarily cross the blood-brain barrier (BBB). However, to be viable in a patient population, good image quality as well as safety of the administration should be demonstrated. This work provides radiation dosimetry calculations and simulations related to the radiation safety of performing such experiments in a human cohort. METHODS: We performed Monte Carlo (MC) simulations to estimate radiation dose to the skin inside a cylindrical model of the nasal cavity assuming a homogenous distribution layer of 11 C and 18 F and calculated a geometry conversion factor (FP-C ) which can be used to convert from a planar geometry to a cylindrical geometry using more widely available software tools. We compared radiation doses from our simulated cylindrical geometry with the planar dose estimates employing our geometry conversion factor from VARSKIN 6.1 software and also from an analytical equation. Furthermore, in order to estimate radiation dosimetry to surrounding organs of interest, we performed a voxelized MC simulation of a fixed radioactivity inside the nasal cavity and calculated S-values to organs such as the eyes, thyroid, and brain. RESULTS: MC simulations of contamination scenarios using planar absorbed doses of 15.50 and 8.60 mGy/MBq for 18 F and 11 C, respectively, and 35.70 and 19.80 mGy/MBq per hour for cylindrical geometries, leading to determination of an FP-C of 2.3. Planar absorbed doses (also in units of mGy/MBq) determined by the analytical equation were 16.96 and 8.68 (18 F and 11 C) and using VARSKIN were 16.60 and 9.26 (18 F and 11 C), respectively. Application of FP-C to these results demonstrates values with a maximum difference of 9.41% from the cylindrical geometry MC calculation, demonstrating that when accounting for geometry, more simplistic techniques can be utilized to estimate IN dosimetry. Voxelized MC simulations of radiation dosimetry from a fixed source of 1 MBq of activity confined to the nasal cavity resulted in S-values to the thyroid, eyes, and brain of 1.72 x 10-6 , 1.93 x 10-5 , and 3.51 x 10-6  mGy/MBq·s, respectively, for 18 F and 1.80 × 10-6 , 1.95 × 10-5 , and 3.54 × 10-6  mGy/MBq·s for 11 C. CONCLUSION: Dosimetry concerns about IN administrations of PET radiotracers should be considered before clinical use. Values presented in the simulations such as the S-values can be further used for assessment of absorbed doses in cases of IN administration, and can be used to develop and adapt specific study protocols. All three presented methods provided similar results when considering the use of a geometry conversion factor for planar to cylindrical geometry, demonstrating that standard tools rather than dedicate MC simulations may be used to perform dose calculations in nasal administrations.