Radiation Principles, Protection and Reporting for Interventional Pulmonology.

The use and availability of diverse advanced X-ray based imaging and guidance systems in the field of interventional pulmonology is rapidly growing. This popularity links inextricably to an increase in ionizing radiation use. Knowing ionizing radiation is hazardous, knowledge and competent use of X-ray imaging and guidance systems are important. The globally implemented As Low As Reasonably Achievable (ALARA) principle demands careful attention to minimizing radiation exposure while achieving the precise goals of the intervention and imaging therein. To allow careful and targeted weighing of risk against reward while using X-ray based equipment, proper background knowledge of physics as well as imaging system aspects are needed. This white paper summarizes the principles of ionizing radiation which are crucial to enhance awareness and interpretation of dosimetric quantities. Consecutively, a consensus on standards for reporting radiation exposure in interventional pulmonology procedures is indicated to facilitate comparisons between different systems, approaches and results. Last but not least, it provides a list of practical measures, considerations and tips to optimize procedural imaging as well as reduce radiation dose to patients and staff.

Extracorporeal Cardiopulmonary Resuscitation: A Narrative Review and Establishment of a Sustainable Program.

The rates of survival with functional recovery for out of hospital cardiac arrest remain unacceptably low. Extracorporeal cardiopulmonary resuscitation (ECPR) quickly resolves the low-flow state of conventional cardiopulmonary resuscitation (CCPR) providing valuable perfusion to end organs. Observational studies have shown an association with the use of ECPR and improved survivability. Two recent randomized controlled studies have demonstrated improved survival with functional neurologic recovery when compared to CCPR. Substantial resources and coordination amongst different specialties and departments are crucial for the successful implementation of ECPR. Standardized protocols, simulation based training, and constant communication are invaluable to the sustainability of a program. Currently there is no standardized protocol for the post-cannulation management of these ECPR patients and, ideally, upcoming studies should aim to evaluate these protocols.

Utilizing the index for mortality prediction after cardiac transplantation risk score to predict hospital resource consumption.

OBJECTIVE: The index for mortality prediction after cardiac transplantation (IMPACT) risk score incorporates 12 preoperative recipient-specific variables, and has been validated as an accurate predictor of short- and long-term mortality after orthotopic heart transplantation (OHTx). We believe it can also be used to predict hospital costs, and we hypothesize that higher preoperative IMPACT risk scores are associated with increased hospital resource consumption. METHODS: All OHTx patients ≥18 years of age at our institution were reviewed from 1 January 2000 to 31 December 2014. Total index hospitalization costs post-transplant were extracted and presented in 2014 consumer price index inflation-adjusted US dollars. Patients were stratified into quartiles (Q) according to IMPACT risk scores. Logarithmic transformation normalized cost data, and linear regression assessed for correlation. A comparison of cost between Q of IMPACT risk score was performed using rank-sum and Kruskal-Wallis tests. Survival was estimated using the Kaplan-Meier method. RESULTS: Three hundred fifty-six (n = 356) OHTx were performed during the study period. The median IMPACT score for the cohort was five (interquartile range [IQR] 3-6). Eight (2.2%) patients died within 30-days and 1-year Kaplan-Meier survival was 88.3%. The median length of stay (LOS) was 16 (IQR 14-24) days. The median hospital cost for index admission was $222 200 (IQR:$169 200-$313 700). Median LOS was longer in Q4 vs Q1 (18 days vs 15 days, P = .01) and index hospital costs in Q4 were significantly higher compared to Q1 patients ($280 400 vs $205 000, P < .01). There was a significant positive correlation between IMPACT risk score and cost (regression coefficient .04, P < .01). CONCLUSION: This is the first study in adult cardiac transplantation to identify a positive correlation between hospital cost and recipient risk using the IMPACT risk score. Cost and resource consumption for the index admission after OHTx were significantly higher in the highest IMPACT risk Q compared with patients in the lowest Q.

Associations Between National Board Exam Performance and Residency Program Emphasis on Patient Safety and Interprofessional Teamwork.

OBJECTIVE: Several aspects of medical training may contribute to the ultimate goal of producing excellent physicians whose patients will have the best possible outcomes. However, the relative importance of education, evaluation and feedback, duty hours, practice structure, and program culture in achieving this goal is unclear. This study assessed associations among in-training exam performance, Accreditation Council for Graduate Medical Education (ACGME) Resident Survey responses, and American Board of Medical Specialties (ABMS) national board exam performance. METHODS: Residency training programs at a university teaching hospital were classified as having 5-year first-time ABMS pass rates above (n=12) or below (n=3) the national average for their specialty. These groups were compared by ACGME Resident Survey data and in-training exam performance. RESULTS: Surveys were collected from 484/543 eligible residents (89%), including 177 surveys from programs with below-average board pass rates and 307 surveys from programs with aboveaverage board pass rates. In-training exam performance was similar between groups. Aboveaverage programs had stronger agreement with statements that their culture reinforced patient safety (4.72 vs. 4.30, p=0.006) and that information was not lost during transitions of care (4.14 vs. 3.63, p=0.001). Although the occurrence of interprofessional teamwork was similar between groups, above-average programs had stronger agreement with the statement that interprofessional teamwork was effective (4.60 vs. 4.17, p=0.003). CONCLUSION: Residency programs emphasizing patient safety and effective interprofessional teamwork had above-average first-time national board pass rates.

Postoperative surgical trainee opioid prescribing practices (POST OPP): an institutional study.

BACKGROUND: Increasing mortality from opioid overdoses has prompted increased focus on prescribing practices of physicians. Unfortunately, resident physicians rarely receive formal education in effective opioid prescribing practices or postoperative pain management. Data to inform surgical training programs regarding the utility and feasibility of formal training are lacking. METHODS: Following Institutional Review Board approval, a single institution's resident physicians who had completed at least one surgical rotation were surveyed to assess knowledge of pain management and evaluate opioid prescribing practices. RESULTS: Fifty-three respondents (68% males and 32% females) completed the survey. Most respondents denied receiving formal instruction in opioid pain medication prescribing practices during either medical school (62.3%) or residency (56.6%); however, nearly all respondents stated they were aware of the side effects of opioid pain medications, and a majority felt confident in their knowledge of opioid pharmacokinetics and pharmacodynamics. Of the respondents, 47% either "agreed" or "strongly agreed" that they prescribed more opioid medications than necessary to patients being discharged following a surgical procedure. Individual case scenario responses demonstrated variability in the number of morphine milligram equivalents prescribed across scenarios (P < 0.001). Male and nonsurgical specialty respondents reported prescribing significantly fewer overall morphine milligram equivalents in these scenarios. CONCLUSIONS: This pilot study shows wide variability in opioid prescribing practices and attitudes toward pain management among surgical trainees, illustrating the potential utility of formal education in pain management and effective prescribing of these medications. A broader assessment of surgical trainees' knowledge and perception of opioid prescribing practices is warranted to facilitate the development of such a program.

Predictors of CT Radiation Dose and Their Effect on Patient Care: A Comprehensive Analysis Using Automated Data.

Purpose To determine patient, vendor, and institutional factors that influence computed tomography (CT) radiation dose. Materials and Methods The relevant institutional review boards approved this HIPAA-compliant study, with waiver of informed consent. Volume CT dose index (CTDIvol) and effective dose in 274 124 head, chest, and abdominal CT examinations performed in adult patients at 12 facilities in 2013 were collected prospectively. Patient, vendor, and institutional characteristics that could be used to predict (a) median dose by using linear regression after log transformation of doses and (b) high-dose examinations (top 25% of dose within anatomic strata) by using modified Poisson regression were assessed. Results There was wide variation in dose within and across medical centers. For chest CTDIvol, overall median dose across all institutions was 11 mGy, and institutional median dose was 7-16 mGy. Models including patient, vendor, and institutional factors were good for prediction of median doses (R2 = 0.31-0.61). The specific institution where the examination was performed (reflecting the specific protocols used) accounted for a moderate to large proportion of dose variation. For chest CTDIvol, unadjusted median CTDIvol was 16.5 mGy at one institution and 6.7 mGy at another (adjusted relative median dose, 2.6 mGy [95% confidence interval: 2.5, 2.7]). Several variables were important predictors that a patient would undergo high-dose CT. These included patient size, the specific institution where CT was performed, and the use of multiphase scanning. For example, while 49% of patients (21 411 of 43 696) who underwent multiphase abdominal CT had a high-dose examination, 8% of patients (4977 of 62 212) who underwent single-phase CT had a high-dose examination (adjusted relative risk, 6.20 [95% CI: 6.17, 6.23]). If all patients had been examined with single-phase CT, 69% (18 208 of 26 388) of high-dose examinations would have been eliminated. Patient size, institutional-specific protocols, and multiphase scanning were the most important predictors of dose (change in R2 = 8%-32%), followed by manufacturer and iterative reconstruction (change in R2, 0.2%-15.0%). Conclusion CT doses vary considerably within and across facilities. The primary factors that influenced dose variation were multiphase scanning and institutional protocol choices. It is unknown if the variation in these factors influenced diagnostic accuracy. © RSNA, 2016.

Tumor-Targeted Multimodal Optical Imaging with Versatile Cadmium-Free Quantum Dots.

The rapid development of fluorescence imaging technologies requires concurrent improvements in the performance of fluorescent probes. Quantum dots have been extensively used as an imaging probe in various research areas because of their inherent advantages based on unique optical and electronic properties. However, their clinical translation has been limited by the potential toxicity especially from cadmium. Here, a versatile bioimaging probe is developed by using highly luminescent cadmium-free CuInSe2/ZnS core/shell quantum dots conjugated with CGKRK (Cys-Gly-Lys-Arg-Lys) tumor-targeting peptides. This probe exhibits excellent photostability, reasonably long circulation time, minimal toxicity, and strong tumor-specific homing property. The most important feature of this probe is that it shows distinctive versatility in tumor-targeted multimodal imaging including near-infrared, time-gated, and two-photon imaging in different tumor models. In a glioblastoma mouse model, the targeted probe clearly denotes tumor boundaries and positively labels a population of diffusely infiltrating tumor cells, suggesting its utility in precise tumor detection during surgery. This work lays a foundation for potential clinical translation of the probe.

Calciphylaxis of the Breast: A Case Report and Literature Review.

Calciphylaxis, or calcific uremic arteriolopathy, is a rare but particularly morbid condition involving systemic medial calcification of arterioles causing ischemia and subsequent tissue necrosis. Although most commonly occurring over the abdomen and proximal extremities, calciphylaxis can present on nearly any skin surface with a tendency toward areas of increased adiposity. We report a case of a 53-year-old female with end-stage renal disease who presented with bilateral palpable breast masses and overlying skin changes. Diagnostic mammography and percutaneous biopsy of the lesion facilitated the diagnosis of calciphylaxis and she was treated with medical therapy, local wound care, and eventual tissue extirpation. Due to the morbidity attributed to calciphylaxis and associated wound complications, surgical extirpation is at times unavoidable. Once malignancy has been excluded, we recommend nonoperative management with prompt referral to Nephrology for medical optimization, reserving surgical debridement for nonhealing wounds and superinfection.

Radiation Doses in Consecutive CT Examinations from Five University of California Medical Centers.

PURPOSE: To summarize data on computed tomographic (CT) radiation doses collected from consecutive CT examinations performed at 12 facilities that can contribute to the creation of reference levels. MATERIALS AND METHODS: The study was approved by the institutional review boards of the collaborating institutions and was compliant with HIPAA. Radiation dose metrics were prospectively and electronically collected from 199 656 consecutive CT examinations in 83 181 adults and 3871 consecutive CT examinations in 2609 children at the five University of California medical centers during 2013. The median volume CT dose index (CTDIvol), dose-length product (DLP), and effective dose, along with the interquartile range (IQR), were calculated separately for adults and children and stratified according to anatomic region. Distributions for DLP and effective dose are reported for single-phase examinations, multiphase examinations, and all examinations. RESULTS: For adults, the median CTDIvol was 50 mGy (IQR, 37-62 mGy) for the head, 12 mGy (IQR, 7-17 mGy) for the chest, and 12 mGy (IQR, 8-17 mGy) for the abdomen. The median DLPs for single-phase, multiphase, and all examinations, respectively, were as follows: head, 880 mGy · cm (IQR, 640-1120 mGy · cm), 1550 mGy · cm (IQR, 1150-2130 mGy · cm), and 960 mGy · cm (IQR, 690-1300 mGy · cm); chest, 420 mGy · cm (IQR, 260-610 mGy · cm), 880 mGy · cm (IQR, 570-1430 mGy · cm), and 550 mGy · cm (IQR 320-830 mGy · cm); and abdomen, 580 mGy · cm (IQR, 360-860 mGy · cm), 1220 mGy · cm (IQR, 850-1790 mGy · cm), and 960 mGy · cm (IQR, 600-1460 mGy · cm). Median effective doses for single-phase, multiphase, and all examinations, respectively, were as follows: head, 2 mSv (IQR, 1-3 mSv), 4 mSv (IQR, 3-8 mSv), and 2 mSv (IQR, 2-3 mSv); chest, 9 mSv (IQR, 5-13 mSv), 18 mSv (IQR, 12-29 mSv), and 11 mSv (IQR, 6-18 mSv); and abdomen, 10 mSv (IQR, 6-16 mSv), 22 mSv (IQR, 15-32 mSv), and 17 mSv (IQR, 11-26 mSv). In general, values for children were approximately 50% those for adults in the head and 25% those for adults in the chest and abdomen. CONCLUSION: These summary dose data provide a starting point for institutional evaluation of CT radiation doses.

Transanal endoscopic microsurgery colorectal anastomosis: a critical step to natural orifice colorectal surgery in humans.

BACKGROUND: Transanal endoscopic microsurgery is used in the surgical management of advanced rectal polyps and early rectal cancers. There are case reports of transanal endoscopic microsurgery colorectal anastomoses being performed with laparoscopic assistance in humans. METHODS: The concept of a transanal endoscopic microsurgery colorectal anastomosis without laparoscopic assistance has been discussed and trialed on animal and cadaveric specimens; however, to date, there have been no technical reports of this particular procedure in the literature. RESULTS: We present a technical note describing a transanal endoscopic microsurgery intraperitoneal colorectal anastomosis in a live human without laparoscopic assistance.

Fluorescent-tilmanocept for tumor margin analysis in the mouse model.

BACKGROUND: Dendritic cells (DC) are localized in close proximity to cancer cells in many well-known tumors, and thus maybe a useful target for tumor margin assessment. MATERIALS AND METHODS: [(99m)Tc]- cyanine 7 (Cy7)-tilmanocept was synthesized and in vitro binding assays to bone marrow-derived DC were performed. Fifteen mice, implanted with either 4T1 mouse mammary or K1735 mouse melanoma tumors, were administered 1.0 nmol of [(99m)Tc]-Cy7-tilmanocept via tail vein injection. After fluorescence imaging 1 or 2 h after injection, the tumor, muscle, and blood were assayed for radioactivity to calculate percent-injected dose. Digital images of the tumors after immunohistochemical staining for DC were analyzed to determine DC density. RESULTS: In vitro binding demonstrated subnanomolar affinity of [(99m)Tc]-Cy7-tilmanocept to DC (KA = 0.31 ± 0.11 nM). After administration of [(99m)Tc]-Cy7-tilmanocept, fluorescence imaging showed a 5.5-fold increase in tumor signal as compared with preinjection images and a 3.3-fold difference in fluorescence activity when comparing the tumor with the surgical bed after tumor excision. Immunohistochemical staining analysis demonstrated that DC density positively correlated with tumor percent of injected dose per gram (r = 0.672, P = 0.03), and higher DC density was observed at the periphery versus center of the tumor (186 ± 54 K versus 64 ± 16 K arbitrary units, P = 0.001). CONCLUSIONS: [(99m)Tc]-Cy7-tilmanocept exhibits in vitro and in vivo tumor-specific binding to DC and maybe useful as a tumor margin targeting agent.

Fluorescent Guided Sentinel Lymph Mapping of the Oral Cavity with Fluorescent-Labeled Tilmanocept.

OBJECTIVE: With the shift toward utilization of sentinel lymph node biopsy (SLNB) in oral cavity cancer, improved techniques for intraoperative sentinel node identification are needed. This study investigates the feasibility of fluorescently labeled tilmanoscept in SLNB in an oral cancer rabbit model. METHODS: An animal study was designed using 21 healthy male New Zealand rabbits. Gallium-68-labeled tilmanocept labeled with IRDye800CW was injected submucosally into the buccal mucosa (n = 6) or lateral tongue (n = 7) followed by PET imaging. One hour after injection, SLNB was performed using fluorescence imaging followed by a bilateral neck dissection and sampling of non-nodal surrounding tissue. All tissues were measured for radioactivity and fluorescence. In addition, eight rabbits were injected with delayed SLNB performed 48 h after injection. RESULTS: Buccal injections all had ipsilateral SLN drainage and tongue injections exhibited 18.2% contralateral drainage. An average of 1.9 ± 1.0 SLN (range 1-5) were identified. In addition, an average of 16.9 ± 3.3 non-sentinel lymph nodes were removed per animal. SLNs had an average of 0.69 ± 0.60 percent-of-injected dose (%ID) compared with non-sentinel nodes with 0.012 ± 0.025 %ID and surrounding tissue with 0.0067 ± 0.015 %ID. There was 98.0% agreement between sentinel lymph nodes identified using fluorescence compared to radioactivity with Cohen's kappa coefficient of 0.879. In 48-h delayed SLNB, results were consistent with 97.8% agreement with radioactivity and Cohen's Kappa coefficient of 0.884. Fluorescence identified additional lymph nodes that were not identified by radioactivity, and with one false negative. CONCLUSION: Fluorescent-labeled Tc-99 m-tilmanocept represents a highly accurate adjunct to enhance SLNB for oral cavity cancer. LEVEL OF EVIDENCE: N/A Laryngoscope, 134:1299-1307, 2024.

Enzyme-directed assembly of nanoparticles in tumors monitored by in vivo whole animal imaging and ex vivo super-resolution fluorescence imaging.

Matrix metalloproteinase enzymes, overexpressed in HT-1080 human fibrocarcinoma tumors, were used to guide the accumulation and retention of an enzyme-responsive nanoparticle in a xenograft mouse model. The nanoparticles were prepared as micelles from amphiphilic block copolymers bearing a simple hydrophobic block and a hydrophilic peptide brush. The polymers were end-labeled with Alexa Fluor 647 dyes leading to the formation of labeled micelles upon dialysis of the polymers from DMSO/DMF to aqueous buffer. This dye-labeling strategy allowed the presence of the retained material to be visualized via whole animal imaging in vivo and in ex vivo organ analysis following intratumoral injection into HT-1080 xenograft tumors. We propose that the material is retained by virtue of an enzyme-induced accumulation process whereby particles change morphology from 20 nm spherical micelles to micrometer-scale aggregates, kinetically trapping them within the tumor. This hypothesis is tested here via an unprecedented super-resolution fluorescence analysis of ex vivo tissue slices confirming a particle size increase occurs concomitantly with extended retention of responsive particles compared to unresponsive controls.

Phospholipid/Carbocyanine Dye-Shelled Microbubbles as Ultrasound-Modulated Fluorescent Contrast Agents.

Fluorescent microbubbles have been fabricated with the capacity to have their emission modulated by ultrasound. These contrast agent particles could potentially be used in the future to extract fluorescence modulation from a strong light background to increase imaging depth and resolution in scattering media. Fluorescence intensity modulation was demonstrated at the ultrasound driving frequency.

Consequences of anastomotic leaks after minimally invasive esophagectomy: A single-center experience.

Background: Anastomotic leak (AL) after minimally invasive esophagectomy (MIE) is a well-described source of morbidity for patients undergoing surgical treatment of esophageal neoplasm. With improved early recognition and endoscopic management techniques, the long-term impact remains unclear. Methods: A retrospective review was conducted of patients who underwent MIE for esophageal neoplasm between January 2015 and June 2021 at a single institution. Cohorts were stratified by development of AL and subsequent management. Baseline demographics, perioperative data, and post-operative outcomes were examined. Results: During this period, 172 MIEs were performed, with 35 of 172 (20.3%) complicated by an AL. Perioperative factors independently associated with AL were post-operative blood transfusion (leak rate 52.9% versus 16.8%; p = 0.0017), incompleteness of anastomotic rings (75.0% vs 19.1%; p = 0.027), and receiving neoadjuvant therapy (18.5% vs 30.8%; p < 0.0001). Inferior short-term outcomes associated with AL included number of esophageal dilations in the first post-operative year (1.40 vs 0.46, p = 0.0397), discharge disposition to a location other than home (22.9% vs 8.8%, p = 0.012), length of hospital stay (17.7 days vs 9.6 days; p = 0.002), and time until jejunostomy tube removal (134 days vs 79 days; p = 0.0023). There was no significant difference in overall survival between patients with or without an AL at 1 year (79% vs 83%) or 5 years (50% vs 47%) (overall log rank p = 0.758). Conclusions: In this large single-center series of MIEs, AL was associated with inferior short-term outcomes including hospital length of stay, discharge disposition other than to home, and need for additional endoscopic procedures, without an accompanying impact on 1-year or 5-year survival. Key message: In this large, single-center series of minimally invasive esophagectomies, anastomotic leak was associated with worse short-term outcomes including hospital length of stay, discharge disposition other than to home, and need for additional endoscopic procedures, but was not associated with worse long-term survival. The significant association between neoadjuvant therapy and decreased leak rates is difficult to interpret, given the potential for confounding factors, thus careful attention to modifiable pre- and peri-operative patient factors associated with anastomotic leak is warranted.

Macroevolutionary diversity of traits and genomes in the model yeast genus Saccharomyces.

Species is the fundamental unit to quantify biodiversity. In recent years, the model yeast Saccharomyces cerevisiae has seen an increased number of studies related to its geographical distribution, population structure, and phenotypic diversity. However, seven additional species from the same genus have been less thoroughly studied, which has limited our understanding of the macroevolutionary events leading to the diversification of this genus over the last 20 million years. Here, we show the geographies, hosts, substrates, and phylogenetic relationships for approximately 1,800 Saccharomyces strains, covering the complete genus with unprecedented breadth and depth. We generated and analyzed complete genome sequences of 163 strains and phenotyped 128 phylogenetically diverse strains. This dataset provides insights about genetic and phenotypic diversity within and between species and populations, quantifies reticulation and incomplete lineage sorting, and demonstrates how gene flow and selection have affected traits, such as galactose metabolism. These findings elevate the genus Saccharomyces as a model to understand biodiversity and evolution in microbial eukaryotes.

A receptor-targeted fluorescent radiopharmaceutical for multireporter sentinel lymph node imaging.

PURPOSE: To determine the imaging and receptor-binding properties of a multireporter probe designed for sentinel lymph node (SLN) mapping via nuclear and fluorescence detection. MATERIALS AND METHODS: The animal experiments were approved by the institutional animal care and use committee. A multireporter probe was synthesized by covalently attaching cyanine 7 (Cy7), a near-infrared cyanine dye, to tilmanocept, a radiopharmaceutical that binds to a receptor specific to recticuloendothelial cells. In vitro binding assays of technetium 99m (99mTc)-labeled Cy7 tilmanocept were conducted at 4°C by using receptor-bearing macrophages. Optical SLN imaging after foot pad administration was performed by using two molar doses of Cy7 tilmanocept. Six mice were injected with 0.11 nmol of 99mTc-labeled Cy7 tilmanocept (low-dose group); an additional six mice were injected with 31 nmol of 99mTc-labeled Cy7 tilmanocept (high-dose group) to saturate the receptor sites within the SLN. After 2.5 hours of imaging, the mice were euthanized, and the sentinel and distal lymph nodes were excised and assayed for radioactivity for calculation of SLN percentage of injected dose and extraction. Four mice were used as controls for autofluorescence. Standard optical imaging software was used to plot integrated fluorescence intensity against time for calculation of the SLN uptake rate constant and scaled peak intensity. Significance was calculated by using the Student t test. RESULTS: In vitro binding assays showed subnanomolar affinity (mean dissociation constant, 0.25 nmol/L±0.10 [standard deviation]). Fluorescence imaging showed a detection sensitivity of 1.6×10(3) counts·sec(-1)·µW(-1) per picomole of Cy7. All four imaging metrics (percentage of injected dose, SLN extraction, SLN uptake rate constant, and expected peak fluorescence intensity) exhibited higher values (P=.005 to P=.042) in the low-dose group than in the high-dose group; this finding was consistent with receptor-mediated image formation. CONCLUSION: The multireporter probe 99mTc-labeled Cy7 tilmanocept exhibits in vitro and in vivo receptor-binding properties for successful receptor-targeted SLN mapping with nuclear and optical imaging.

Tumor necrosis factor α-mediated cleavage and inactivation of SirT1 in human osteoarthritic chondrocytes.

OBJECTIVE: The protein deacetylase SirT1 positively regulates cartilage-specific gene expression, while the proinflammatory cytokine tumor necrosis factor α (TNFα) negatively regulates these same genes. This study was undertaken to test the hypothesis that SirT1 is adversely affected by TNFα, resulting in altered gene expression. METHODS: Cartilage-specific gene expression, SirT1 activity, and results of chromatin immunoprecipitation analysis at the α2(I) collagen enhancer site were determined in RNA, protein extracts, and nuclei of human osteoarthritic chondrocytes left untreated or treated with TNFα. Protein extracts from human chondrocytes transfected with epitope-tagged SirT1 that had been left untreated or had been treated with TNFα were analyzed by immunoblotting with SirT1 and epitope-specific antibodies. The 75-kd SirT1-reactive protein present in TNFα-treated extracts was identified by mass spectroscopy, and its amino-terminal cleavage site was identified via Edman sequencing. SirT1 activity was assayed following an in vitro cathepsin B cleavage reaction. Cathepsin B small interfering RNA (siRNA) was transfected into chondrocytes left untreated or treated with TNFα. RESULTS: TNFα-treated chondrocytes had impaired SirT1 enzymatic activity and displayed 2 forms of the enzyme: a full-length 110-kd protein and a smaller 75-kd fragment. The 75-kd SirT1 fragment was found to lack the carboxy-terminus. Cathepsin B was identified as the TNFα-responsive protease that cleaves SirT1 at residue 533. Reducing cathepsin B levels via siRNA following TNFα exposure blocked the generation of the 75-kd SirT1 fragment. CONCLUSION: These data indicate that TNFα, a cytokine that mediates joint inflammation in arthritis, induces cathepsin B-mediated cleavage of SirT1, resulting in reduced SirT1 activity. This reduced SirT1 activity correlates with the reduced cartilage-specific gene expression evident in these TNFα-treated cells.

Successful Lung Transplantation for Severe Post-COVID-19 Pulmonary Fibrosis.

Lung transplantation has been well described for patients with coronavirus disease 2019 (COVID-19) in the acute setting, but less so for the resulting pulmonary sequelae. This report describes a case of lung transplantation for post-COVID-19 pulmonary fibrosis. A 52-year-old woman contracted COVID-19 in July 2020 and mounted a partial recovery, but she went on to have declining function over the ensuing 3 months, with development of fibrocystic lung changes. She underwent bilateral lung transplantation and recovered rapidly, was discharged home on postoperative day 14, and has done well in follow-up. This case report demonstrates that lung transplantation is an acceptable therapy for post-COVID-19 pulmonary fibrosis.

SirT1 enhances survival of human osteoarthritic chondrocytes by repressing protein tyrosine phosphatase 1B and activating the insulin-like growth factor receptor pathway.

OBJECTIVE: The protein deacetylase SirT1 inhibits apoptosis in a variety of cell systems by distinct mechanisms, yet its role in chondrocyte death has not been explored. We undertook the present study to assess the role of SirT1 in the survival of osteoarthritic (OA) chondrocytes in humans. METHODS: SirT1, protein tyrosine phosphatase 1B (PTP1B), and PTP1B mutant expression plasmids as well as SirT1 small interfering RNA (siRNA) and PTP1B siRNA were transfected into primary human chondrocytes. Levels of apoptosis were determined using flow cytometry, and activation of components of the insulin-like growth factor receptor (IGFR)/Akt pathway was assessed using immunoblotting. OA and normal knee cartilage samples were subjected to immunohistochemical analysis. RESULTS: Expression of SirT1 in chondrocytes led to increased chondrocyte survival in either the presence or the absence of tumor necrosis factor alpha/actinomycin D, while a reduction of SirT1 by siRNA led to increased chondrocyte apoptosis. Expression of SirT1 in chondrocytes led to activation of IGFR and the downstream kinases phosphatidylinositol 3-kinase, phosphoinosite-dependent protein kinase 1, mTOR, and Akt, which in turn phosphorylated MDM2, inhibited p53, and blocked apoptosis. Activation of IGFR occurs at least in part via SirT1-mediated repression of PTP1B. Expression of PTP1B in chondrocytes increased apoptosis and reduced IGFR phosphorylation, while down-regulation of PTP1B by siRNA significantly decreased apoptosis. Examination of cartilage from normal donors and OA patients revealed that PTP1B levels are elevated in OA cartilage in which SirT1 levels are decreased. CONCLUSION: For the first time, it has been demonstrated that SirT1 is a mediator of human chondrocyte survival via down-regulation of PTP1B, a potent proapoptotic protein that is elevated in OA cartilage.