Prediction of Admission to Intensive Care Unit and 1-Year Mortality After Acute Pancreatitis With Walled-Off Pancreatic Necrosis: A Retrospective, Single-Center Cohort Study.

BACKGROUND AND AIMS: Pancreatic walled-off necrosis (WON) carries significant mortality and morbidity risks, often necessitating intensive care unit (ICU) admission. This retrospective study aimed to evaluate whether routine biochemical parameters at the time of the index endoscopic procedure could predict ICU admission and 1-year mortality following endoscopic treatment of WON. MATERIALS AND METHODS: We retrospectively identified 201 consecutive patients who underwent endoscopic drainage for WON between January 1, 2010, and December 31, 2020. Associations between routine biochemical blood tests and outcomes were assessed using logistic regression models. RESULTS: Within 1 year of the index endoscopy, 31 patients (15.4%) died, and 40 (19.9%) were admitted to the ICU due to sepsis. Preoperative electrolyte disturbances were more prevalent among ICU-admitted patients and nonsurvivors. Hyperkalemia, hypoalbuminemia, and elevated urea were significant predictors of 1-year mortality, while hypernatremia, elevated serum creatinine, and hypoalbuminemia predicted ICU admission. Predictive models exhibited good discriminative ability, with an AUC of 0.84 (95% CI,0,75-0.93) for 1-year mortality and 0.86 (95%CI, 0.79-0.92) for ICU admission. CONCLUSIONS: Preoperative imbalances in routine blood tests effectively predict adverse outcomes in endoscopically treated WON patients.

COVID-Related Stressors and Psychological Distress Among Chicago Residents: the Moderating Role of Race.

BACKGROUND: Racial and ethnic minorities have been disproportionately affected by the COVID-19 pandemic and have experienced greater financial loss, housing instability, and food insecurity due to COVID-related restrictions. As a result, Black and Hispanic communities may be at greater risk of experiencing psychological distress (PD). METHODS: Using data collected between October 2020 and January 2021from 906 Black (39%), White (50%), and Hispanic (11%) adults, we assessed racial/ethnic differences in the effect of three COVID-related stressors-employment stress, housing instability, and food insecurity-on PD using ordinary least square regression. RESULTS: Black adults reported lower PD levels compared to White adults (ß = - 0.23, P < 0.001), but Hispanic adults did not differ significantly from White adults. COVID-related housing instability (ß = 0.46, P < 0.001), food insecurity (ß = 0.27, P < 0.001), and employment stress (ß = 0.29, P < 0.001) were associated with higher PD. Employment stress was the only stressor to differentially affect PD by race/ethnicity. Among those that reported employment stress, Black adults had lower levels of distress compared to Whites (ß = - 0.54, P < 0.001) and Hispanics (ß = - 0.04, P = 0.85). CONCLUSION: Despite relatively high exposure to COVID-related stressors, Black respondents had lower levels of PD compared to Whites and Hispanics which may reflect differences in race-specific coping mechanisms. Future research is needed to elucidate the nuances of these relationships and identify policies and interventions that prevent and minimize the impact of employment, food, and housing-related stressors and support coping mechanisms that promote mental health among minority populations, such as policies that support easier access to mental health and financial and housing assistance.

Understanding COVID-19 Risk Perceptions and Precautionary Behaviors in Black Chicagoans: A Grounded Theory Approach.

OBJECTIVES: To determine whether actual community-level risk for COVID-19 in the Black community influenced individual perceptions of community-level and personal risk and how self-assessment of personal risk was reflected in the adoption of COVID-19 precautionary behaviors. METHODS: Semistructured interviews were conducted with 20 Black Chicago adults from February to July 2021. A grounded theory approach was used for the qualitative analysis and initial, focused, and theoretical coding were performed. RESULTS: We developed a grounded model consisting of four major themes: (a) Pre-Existing Health Conditions; (b) Presence of COVID-19 Infection in Participant Social Network; (c) COVID-19-Related Information, Participant Trust, and Perceived Personal Risk; and (d) Perceived Higher Burden of COVID-19 in the Black Community. CONCLUSIONS: Higher perceptions of personal risk were shaped by pre-existing health conditions and experiences with COVID-19 in one's social network but were not influenced by perceived higher burden of COVID-19 in the Black community. POLICY IMPLICATIONS: Black adults' perceptions of their individual risk and precautionary behaviors were not congruent with public health data and recommendations. Therefore, COVID-19 messaging and mitigation should be informed by local community engagement and transparent communication.

Examining the Association Between Episiotomy and Severe Perineal Tears in a Tertiary Care Center Implementing a Restrictive Episiotomy Policy.

Background Perineal lacerations are feared complications of vaginal delivery, especially the severe types (third- and fourth-degree tears). World Health Organization (WHO) recommended restrictive episiotomy practice after alarming literature linked the increase in severe tears with routine episiotomy. Therefore, this study aimed to measure the association between episiotomy and the incidence of third- and fourth-degree perineal tears and infections in women who underwent episiotomy versus those who did not at a tertiary care center implementing the restrictive episiotomy policy in Jeddah, Saudi Arabia. Methods This retrospective cohort study was conducted in the Department of Obstetrics and Gynecology at King Abdulaziz Medical City (KAMC), Western Region, between May 2016 and May 2018, targeting all pregnant women who underwent normal spontaneous vaginal delivery. The nonprobability convenient sampling technique was used for women who underwent episiotomy. Women without episiotomy (control group) were randomly selected in a 1:1 ratio. The prevalence (incidence) of episiotomy and its association with severe perineal tears were measured. Statistical data were analyzed using SPSS version 27 (IBM Corp., Armonk, NY). A p-value of less than 0.05 was considered significant. Result A total of 7436 deliveries were recorded. At KAMC, episiotomy had a prevalence of 10% and was more common in primipara. The incidence of third-degree tears was 3.3% in the episiotomy group and 0.8% in the control group (odds ratio, 4.1; p = 0.03). None had fourth-degree tears. Furthermore, the infection rate was not significantly different between the two groups (0.1% vs. 0.1%). Using Firth's logistic regression model, primipara emerged as an independent significant risk factor (OR, 3.5 [1.1-11.2]; p = 0.035) while the trend toward increased risk for tear development in the episiotomy group became statistically insignificant (OR, 2.3 [0.7-8.0]; p = 0.19). A post hoc examination to observe the association between episiotomy exposure and BMI using a stepwise logistic regression model showed that parity and age were independent risk factors for episiotomy, with OR values of 2.2 (1.6-3.2) and 0.9 (0.88-0.94), respectively (p < 0.001). The BMI became insignificant, with an OR of 1.0 (0.7-1.4) (p = 0.96). Conclusion The development of severe perineal tears in a center with a restrictive episiotomy policy is rare. Parity has emerged as an independent risk factor for severe perineal tears. Prospective multicenter research with a larger sample size is recommended to validate this study's findings further and investigate other obstetric measures to reduce severe tears in primi mothers.

Evaluating the Phenotypic and Genomic Characterization of Some Egyptian Phages Infecting Shiga Toxin-Producing Escherichia coli O157:H7 for the Prospective Application in Food Bio-Preservation.

Shiga toxin-producing E. coli (STEC) is considered a worldwide public health and food safety problem. Despite the implementation of various different approaches to control food safety, outbreaks persist. The aim of study is to evaluate the applicability of phages, isolated against STEC O157:H7, as prospective food bio-preservatives. Considering the relatively wide host range and greatest protein diversity, two phages (STEC P2 and P4) from four were furtherly characterized. Complete genome analysis confirmed the absence of toxins and virulence factors-encoding genes. The results confirmed the close relation of STEC P2 to phages of Myoviridae, and STEC P4 to the Podoviridae family. The phages retained higher lytic competence of 90.4 and 92.68% for STEC P2 and P4, respectively with the HTST pasteurization. The strong acidic (pH 1) and alkaline (pH 13) conditions had influential effect on the surviving counts of the two phages. The lowest survivability of 63.37 and 86.36% in STEC P2 and P4 lysate, respectively appeared in 2% bile salt solution after 3 h. The results confirmed the strong effect of simulated gastric fluid (SGF) on the survivability of the two phages comparing with simulated intestinal fluid (SIF). Therefore, the two phages could be applied as a natural alternative for food preservation.

Discharge outcome analysis of 1089 transgender young people referred to paediatric endocrine clinics in England 2008-2021.

INTRODUCTION: The destination of transgender and gender variant young people referred by the National Health Service (NHS) Gender Identity Development Service (GIDS) to, and discharged from the two English paediatric endocrine liaison clinics is not known. METHODS: 1151 young people referred after full assessment by the GIDS; 827 to University College London Hospital since 2008; 324 to Leeds Children's Hospital since 2013. Discharge categorisation was by agreed criteria. Eleven emigrated and 51 self-discharged. 1089 had known outcomes. RESULTS: 999/1089 (91.7%) continued identifying as gender variant. 867/999 (86.8%) were discharged to adult gender identity clinics (GICs). 166/867 (19.1%) of these were <16 years and 701/867 (80.9%) ≥16 years at initial endocrine referral. No sex differences were seen. 38/999 (3.8%) opted for non-NHS services.90/1089 ceased identifying as gender variant. In 32/1089 (2.9%), this was subsequent to their first clinic appointment.58/1089 (5.3%) stopped treatment either with the gonadotropin releasing hormone analogue (GnRHa) or gender-affirming hormones (GAH) and reverted to their birth gender: <16 years (20/217; 9.2%); ≥16 years (38/872; 4.4%).Subdividing further, 16/217 (7.4%) <16 years ceased GnRHa and 4/217 (1.8%) after GAH. Of those ≥16 years, 33/872 (3.8%) ceased GnRHa and 5/872 (0.6%) GAH. CONCLUSIONS: At discharge, 91.7% continued as transgender or gender variant, 86.8% sought ongoing care through NHS GICs. 2.9% ceased identifying as transgender after an initial consultation prior to any endocrine intervention and 5.3% stopped treatment either with GnRHa or GAH, a higher proportion in the <16 year compared with the ≥16 year groups.

Bone mineral density surveillance for childhood, adolescent, and young adult cancer survivors: evidence-based recommendations from the International Late Effects of Childhood Cancer Guideline Harmonization Group.

Childhood, adolescent, and young adult cancer survivors are at increased risk of reduced bone mineral density. Clinical practice surveillance guidelines are important for timely diagnosis and treatment of these survivors, which could improve bone mineral density parameters and prevent fragility fractures. Discordances across current late effects guidelines necessitated international harmonisation of recommendations for bone mineral density surveillance. The International Late Effects of Childhood Cancer Guideline Harmonization Group therefore established a panel of 36 experts from ten countries, representing a range of relevant medical specialties. The evidence of risk factors for very low and low bone mineral density and fractures, surveillance modality, timing of bone mineral density surveillance, and treatment of very low and low bone mineral density were evaluated and critically appraised, and harmonised recommendations for childhood, adolescent, and young adult cancer survivors were formulated. We graded the recommendations based on the quality of evidence and balance between potential benefits and harms. Bone mineral density surveillance is recommended for survivors treated with cranial or craniospinal radiotherapy and is reasonable for survivors treated with total body irradiation. Due to insufficient evidence, no recommendation can be formulated for or against bone mineral density surveillance for survivors treated with corticosteroids. This surveillance decision should be made by the survivor and health-care provider together, after careful consideration of the potential harms and benefits and additional risk factors. We recommend to carry out bone mineral density surveillance using dual-energy x-ray absorptiometry at entry into long-term follow-up, and if normal (Z-score > -1), repeat when the survivor is aged 25 years. Between these measurements and thereafter, surveillance should be done as clinically indicated. These recommendations facilitate evidence-based care for childhood, adolescent, and young adult cancer survivors internationally.

Rapid Behavioral Health Assessment Post-disaster: Developing and Validating a Brief, Structured Module.

To develop and validate a brief, structured, behavioral health module for use by local public health practitioners to rapidly assess behavioral health needs in disaster settings. Data were collected through in-person, telephone, and web-based interviews of 101 individuals affected by Hurricanes Katrina (n = 44) and Sandy (n = 57) in New Orleans and New Jersey in April and May 2018, respectively. Questions included in the core module were selected based on convergent validity, internal consistency reliability, test-retest reliability across administration modes, principal component analysis (PCA), question comprehension, efficiency, accessibility, and use in population-based surveys. Almost all scales showed excellent internal consistency reliability (Cronbach's alpha, 0.79-0.92), convergent validity (r > 0.61), and test-retest reliability (in-person vs. telephone, intra-class coefficient, ICC, 0.75-1.00; in-person vs. web-based ICC, 0.73-0.97). PCA of the behavioral health scales yielded two components to include in the module-mental health and substance use. The core module has 26 questions-including self-reported general health (1 question); symptoms of posttraumatic stress disorder, depression, and anxiety (Primary Care PTSD Screen, Patient Health Questionnaire-4; 8 questions); drinking and other substance use (Alcohol Use Disorders Identification Test-Concise, AUDIT-C; Drug Abuse Screening Test, DAST-10; stand-alone question regarding increased substance use since disaster; 14 questions); prior mental health conditions, treatment, and treatment disruption (3 questions)-and can be administered in 5-10 minutes through any mode. This flexible module allows practitioners to quickly evaluate behavioral health needs, effectively allocate resources, and appropriately target interventions to help promote recovery of disaster-affected communities.

Surgical management of symptomatic osteonecrosis and utility of core decompression of the femoral head in young people with acute lymphoblastic leukaemia recruited into UKALL 2003.

AIMS: Osteonecrosis (ON) can cause considerable morbidity in young people who undergo treatment for acute lymphoblastic leukaemia (ALL). The aims of this study were to determine the operations undertaken for ON in this population in the UK, along with the timing of these operations and any sequential procedures that are used in different joints. We also explored the outcomes of those patients treated by core decompression (CD), and compared this with conservative management, in both the pre- or post-collapse stages of ON. METHODS: UK treatment centres were contacted to obtain details regarding surgical interventions and long-term outcomes for patients who were treated for ALL and who developed ON in UKALL 2003 (the national leukaemia study which recruited patients aged 1 to 24 years at diagnosis of ALL between 2003 and 2011). Imaging of patients with ON affecting the femoral head was requested and was used to score all lesions, with subsequent imaging used to determine the final grade. Kaplan-Meier failure time plots were used to compare the use of CD with non surgical management. RESULTS: Detailed information was received for 85 patients who had developed ON during the course of their ALL treatment. A total of 206 joints were affected by ON. Of all joints affected by ON, 21% required arthroplasty, and 43% of all hips affected went on to be replaced. CD was performed in 30% of hips affected by ON. The majority of the hips were grade 4 or 5 at initial diagnosis of ON. There was no significant difference in time to joint collapse between those joints in which CD was performed, compared with no joint-preserving surgical intervention. CONCLUSION: There is a high incidence of surgery in young people who have received treatment for ALL and who have developed ON. Our results suggest that CD of the femoral head in this group of patients does not delay or improve the rates of femoral head survival. Cite this article: Bone Joint J 2021;103-B(3):589-596.

Randomized Phase II trial of combination chemotherapy with panitumumab or bevacizumab for patients with inoperable biliary tract cancer without KRAS exon 2 mutations.

Biliary tract cancers (BTC) are rare and often diagnosed in late stages with advanced, nonresectable disease. The targeted agents panitumumab and bevacizumab have shown promising outcomes in combination with chemotherapy in other gastrointestinal (GI) cancers. We wanted to investigate if panitumumab or bevacizumab was the most promising drug to add to chemotherapy. Eighty-eight patients were randomized to combination chemotherapy supplemented by either panitumumab 6 mg/kg or bevacizumab 10 mg/kg on Day 1 in Arm A and Arm B, respectively. All patients received gemcitabine 1000 mg/m2 on Day 1, oxaliplatin 60 mg/m2 on Day 1 and capecitabine 1000 mg/m2 twice daily from Days 1 to 7. Treatment was repeated every 2 weeks until progression or for a maximum of 6 months. At progression, crossover was made to the other treatment arm. The primary endpoint was progression-free survival (PFS) at 6 months. With 19 of 45 in Arm A and 23 of 43 in Arm B PFS at 6 months, the primary endpoint was not met. The overall response rate (ORR) was 45% vs 20% (P = .03), median PFS was 6.1 months vs 8.2 months (P = .13) and median overall survival (OS) was 9.5 months vs 12.3 months (P = .47) in Arm A and Arm B, respectively. Our study showed no consistent differences between adding panitumumab or bevacizumab to chemotherapy in nonresectable BTC and none of the two regimens qualify for testing in Phase III. However, we found a higher response rate in the panitumumab arm with potential implication for future trials in the neoadjuvant setting.

Hopelessness Among Middle-Aged and Older Blacks: The Negative Impact of Discrimination and Protecting Power of Social and Religious Resources.

BACKGROUND AND OBJECTIVES: Hopelessness-a state of despair characterized by a negative outlook towards the future and a belief in insurmountable challenges-is a risk factor for major depression, cardiovascular disease, and all-cause mortality among older adults. It is also an understudied consequence of discrimination. Older blacks disproportionately report experiencing discrimination and, as a result, may be at greater risk of feeling hopeless. However, social and religious resources may protect against the adverse effects of discrimination. The current study examines whether social support, social engagement, religious attendance, and religiosity buffer the effects of self-reported everyday discrimination on hopelessness among a nationally representative sample of blacks. RESEARCH DESIGN AND METHODS: Using data from the 2010/2012 psychosocial assessment of the Health and Retirement Study, we regressed hopelessness on everyday discrimination, stratifying by 2 age groups, ages 51-64, representing middle-age (n = 1,302), and age 65 and older, representing old age (n = 887). Interaction terms tested whether each resource moderated the discrimination-hopelessness relationship controlling for depressive symptoms, socioeconomic status, and demographic characteristics. RESULTS: Greater reports of everyday discrimination were associated with higher levels of hopelessness for middle-aged and older blacks. For middle-aged blacks, the resources did not moderate the discrimination-hopelessness relationship; rather, higher levels of support (b = -0.294, p < .01), religiosity (b = -0.297, p < .001), religious attendance (b = -0.218, p < .05) were independently and inversely associated with hopelessness. For older blacks, higher levels of religiosity moderated the discrimination-hopelessness relationship (b = -0.208, p < .05) and higher levels of support (b = -0.304, p < .05) and social engagement (b = -0.236, p < .05) were independently and inversely associated with hopelessness. DISCUSSION AND IMPLICATIONS: Findings suggest that self-reported everyday discrimination increases hopelessness among middle-aged and older blacks but social and religious resources may counterbalance its effects, in age-specific ways, to protect against hopelessness. Religiosity may be especially important for older blacks as a buffer against the negative consequences of discrimination on hopelessness.

British OsteoNEcrosis Study (BONES) protocol: a prospective cohort study to examine the natural history of osteonecrosis in older children, teenagers and young adults with acute lymphoblastic leukaemia and lymphoblastic lymphoma.

INTRODUCTION: Osteonecrosis is a well-recognised treatment-related morbidity risk in patients diagnosed with acute lymphoblastic leukaemia (ALL) and lymphoblastic lymphoma (LBL), with a high rate of affected patients requiring surgical intervention. Patients may have asymptomatic changes on imaging studies that spontaneously regress, and little is known about the natural history of osteonecrotic changes seen. The main aim of the British OsteoNEcrosis Study (BONES) is to determine the incidence of symptomatic and asymptomatic osteonecrosis in the lower extremities of survivors of ALL or LBL diagnosed aged 10-24 years in the UK at different time points in their treatment. This study also aims to identify risk factors for progression and the development of symptomatic osteonecrosis in this population, as well as specific radiological features that predict for progression or regression in those with asymptomatic osteonecrosis METHODS AND ANALYSIS: BONES is a prospective, longitudinal cohort study based at principal treatment centres around the UK. Participants are patients aged 10-24 years diagnosed with ALL or LBL under standard criteria. Assessment for osteonecrosis will be within 4 weeks of diagnosis, at the end of delayed intensification and 1, 2 and 3 years after the start of maintenance therapy. Assessment will consist of MRI scans of the lower limbs and physiotherapy assessment. Clinical and biochemical data will be collected at each of the time points. Bone mineral density data and vertebral fracture assessment using dual-energy X-ray absorptiometry will be collected at diagnosis and annually for 3 years after diagnosis of malignancy. ETHICS AND DISSEMINATION: Ethical approval has been obtained through the Yorkshire and Humber Sheffield Research Ethics Committee (reference number: 16/YH/0206). Study results will be published on the study website, in peer-reviewed journals and presented at relevant conferences and via social media. TRIAL REGISTRATION NUMBER: NCT02598401; Pre-results.

Osteonecrosis in patients with acute lymphoblastic leukaemia: a national questionnaire study.

OBJECTIVES: To establish prevalence, management and long-term outcomes of osteonecrosis (ON) in young people diagnosed with acute lymphoblastic leukaemia (ALL) between 2003 and 2011. DESIGN SETTING PARTICIPANTS: This study assessed ON in 3113 patients aged 1-24 years who participated in the UK national leukaemia study UKALL 2003. UKALL 2003 recruited patients in 40 UK hospitals between 2003 and 2011 and included patients between ages 1 and 25 diagnosed with ALL. RESULTS: 170 patients were diagnosed with ON, giving a prevalence of 5.5%. The multivariable analysis showed that the risk of ON was highest for children aged between 10 and 20 years (ages 10-15 years, OR 23.7, 95% CI 14.8 to 38.0; ages 16-20 years, OR 22.5, 95% CI 12.7 to 39.8, compared with age <10 years). Among ethnic groups, Asian patients had the highest risk of ON (OR 1.92, 95% CI 1.1 to 3.6, compared with White patients). Eighty-five per cent of patients with ON had multifocal ON. Thirty-eight per cent of patients with ON required surgery and 19% of patients with ON required a hip replacement. Fifteen per cent of patients who had surgery still describe significant disability or use of a wheelchair. CONCLUSIONS: ON has considerable morbidity for patients being treated for ALL, with a high burden of surgery. Age and ethnicity were found to be the most significant risk factors for development of ON, with Asian patients and patients aged 10-20 years at diagnosis of ALL at greatest risk. These results will help risk stratify patients at diagnosis of ALL, and help tailor future prospective studies in this area.

Fifteen-minute consultation: The child with short stature.

Short stature can be a cause of distress for children and families. It is not usually pathological, but it is important to identify treatable conditions. This article presents a systematic approach to the evaluation of a child with short stature, covering differential diagnoses, first line investigations and indications for treatment with growth hormone.

Viral causes of acute respiratory infection among Egyptian children hospitalized with severe acute asthma exacerbation.

BACKGROUND: Viral respiratory infections are associated with nearly 80% of asthma exacerbation episodes. These can have severe adverse outcomes in patients with established asthma. AIM: The aim of the study was to identify the viral causes of acute respiratory infection that precipitate acute asthma exacerbation in Egyptian asthmatic children. PATIENTS AND METHODS: The current prospective study was conducted in Cairo University Children's Hospitals from December 2010 to December 2011. All asthmatic children (n=130) aged 2-12 years admitted with asthma exacerbation due to severe lower respiratory tract infection were included. All cases were subjected to nasopharyngeal or throat swabs that were analyzed for common respiratory viruses, including respiratory syncytial virus (RSV), human metapneumovirus (hMPV), influenza B (Flu B), human parainfluenza virus (hPIV), influenza A (H1N1), and adenovirus (ADV) using the real-time PCR technique. All patients were followed up to record the outcome. RESULTS: PCR analysis was positive for one respiratory virus in 54 asthmatic patients (41.5%) and was negative in 76 patients (58.5%), with a high predominance of RSV (51.9%) and hMPV (25.9%) especially in winter and early spring months. Hypoxia was detected in all patients with RSV infection; of these patients, 21.4% were admitted to the ICU, 14.3% required mechanical ventilation, and 14.3% died. In contrast, among those with hMPV infection, hypoxia was detected in 71.4%; none required ICU admission or mechanical ventilation. CONCLUSION AND RECOMMENDATIONS: Viral etiology of lower respiratory tract infections constitutes an important cause of acute asthma exacerbation in asthmatic children admitted to children's hospitals in Cairo, supporting the need for large-scale multicentric studies on asthmatic patients over multiple years using a wider-panel PCR for detection of respiratory viruses.

Do inhaled carbon nanoparticles translocate directly into the circulation in humans?

RATIONALE: Increased exposure to particulate air pollution (PM(10)) is a risk factor for death and hospitalization with cardiovascular disease. It has been suggested that the nanoparticulate component of PM(10) is capable of translocating into the circulation with the potential for direct effects on the vasculature. OBJECTIVE: The study's aim was to determine the extent to which inhaled technetium-99m ((99m)Tc)-labeled carbon nanoparticles (Technegas) were able to access the systemic circulation. METHODS AND MAIN RESULTS: Ten healthy volunteers inhaled Technegas and blood samples were taken sequentially over the following 6 h. Technegas particles were 4-20 nm in diameter and aggregated to a median particle diameter of approximately 100 nm. Radioactivity was immediately detected in blood, with levels increasing over 60 min. Thin-layer chromatography of whole blood identified a species that moved with the solvent front, corresponding to unbound (99m)Tc-pertechnetate, which was excreted in urine. There was no evidence of particle-bound (99m)Tc at the origin. gamma Camera images demonstrated high levels of Technegas retention (95.6 +/- 1.7% at 6 h) in the lungs, with no accumulation of radioactivity detected over the liver or spleen. CONCLUSIONS: The majority of (99m)Tc-labeled carbon nanoparticles remain within the lung up to 6 h after inhalation. In contrast to previous published studies, thin-layer chromatography did not support the hypothesis that inhaled Technegas carbon nanoparticles pass directly from the lungs into the systemic circulation.