Diagnostic Workup and Therapeutic Intervention of Hiatal Hernias Discovered as Incidental Findings on Computed Tomography.

BACKGROUND: Computed tomography imaging routinely detects incidental findings; most research focuses on malignant findings. However, benign diseases such as hiatal hernia also require identification and follow-up. Natural language algorithms can help identify these non-malignant findings. METHODS: Imaging of adult trauma patients from 2010 to 2020 who underwent CT chest/abdomen/pelvis was evaluated using an open-source natural language processor to query for hiatal hernias. Patients who underwent subsequent imaging, endoscopy, fluoroscopy, or operation were retrospectively reviewed. RESULTS: 1087(10.6%) of 10 299 patients had incidental hiatal hernias: 812 small (74.7%) and 275 moderate/large (25.3%). 224 (20.7%) had subsequent imaging or endoscopic evaluation. Compared to those with small hernias, patients with moderate/large hernias were older (66.3 ± 19.4 vs 79.6 ± 12.6 years, P < .001) and predominantly female (403[49.6%] vs 199[72.4%], P < .001). Moderate/large hernias were not more likely to grow (small vs moderate/large: 13[7.6%] vs 8[15.1%], P = .102). Patients with moderate/large hernias were more likely to have an intervention or referral (small vs moderate/large: 6[3.5%] vs 7[13.2%], P = .008). No patients underwent elective or emergent hernia repair. Three patients had surgical referral; however, only one was seen by a surgeon. One patient death was associated with a large hiatal hernia. CONCLUSIONS: We demonstrate a novel utilization of natural language processing to identify patients with incidental hiatal hernia in a large population, and found a 10.6% incidence with only 1.2%. (13/1087) of these receiving a referral for follow-up. While most incidental hiatal hernias are small, moderate/large and symptomatic hernias have high risk of loss-to-follow-up and need referral pipelines to improve patient outcomes.

Implementation and Effectiveness of Opioid Prescribing Guidelines After Hiatal Hernia Repair.

INTRODUCTION: We defined institutional opioid prescribing patterns, established prescribing guidelines, and evaluated the adherence to and effectiveness of these guidelines in association with opioid prescribing after hiatal hernia repair (HHR). METHODS: A retrospective chart review was completed for patients who underwent transthoracic (open) or laparoscopic HHR between January and December 2016. Patient-reported opioid use after surgery was used to establish prescribing recommendations. Guideline efficacy was then evaluated among patients undergoing HHR after implementation (August 2018 to June 2019). Data are reported in oral morphine equivalents (OMEs). RESULTS: The initial cohort included n = 87 patients (35 open; 52 laparoscopic) with a 68% survey response rate. For open repair, median prescription size was 338 mg OME (interquartile range [IQR] 250-420) with patient-reported use of 215 mg OME (IQR 78-308) (P = 0.002). Similarly, median prescription size was 270 mg OME (IQR 200-319) with patient-reported use of 100 mg OME (IQR 4-239) (P < 0.001) for laparoscopic repair. Opioid prescribing guidelines were defined as the 66th percentile of patient-reported opioid use. Postguideline implementation cohort included n = 108 patients (36 open; 72 laparoscopic). Median prescription amount decreased by 54% for open and 43% laparoscopic repair, with no detectable change in the overall refill rate after guideline implementation. Patient education, opioid storage, and disposal practices were also characterized. CONCLUSIONS: Evidence-based opioid prescribing guidelines can be successfully implemented for open and laparoscopic HHR with a high rate of compliance and without an associated increase in opioid refills.

The Early Impact of the COVID-19 Pandemic on Lung, Colorectal, and Breast Cancer Screening and Treatment at a Tertiary Cancer Center.

OBJECTIVES: During the coronavirus-19 pandemic, experts recommended delaying routine cancer screening and modifying treatment strategies. We sought to understand the sequalae of these recommendations. MATERIALS AND METHODS: We performed a retrospective single-center analysis of screening, diagnosis, and treatment of lung, colorectal, and breast cancer. Data was collected from our institutional cancer registry. Prepandemic (2016-2019) was compared with pandemic (2020) data. RESULTS: Three thousand three sixty one screening chest computed tomography scans (CTs), 35,917 colonoscopies, and 48,093 screening mammograms were performed. There was no difference in CTs [81.0 (SEM10.0) vs. 65.6 (SEM3.29), P =0.067] or mammograms [1017.0 (SEM171.8) vs. 809.4 (SEM56.41), P =0.177] in 2020 versus prepandemic. There were fewer colonoscopies in 2020 [651.4 (SEM103.5) vs. 758.91 (SEM11.79), P =0.043]. There was a decrease in cancer diagnoses per month in 2020 of lung [22.70 (SEM1.469) vs. 28.75 (SEM0.8216), P =0.003] and breast [38.56 (SEM6.133) vs. 51.82 (SEM1.257), P =0.001], but not colorectal [13.11 (SEM1.467) vs. 15.88 (SEM0.585), P =0.074] cancer. There was no change in stage at presentation for lung ( P =0.717), breast ( P =0.115), or colorectal cancer ( P =0.180). Lung had a shorter time-to-treatment in 2020 [38.92 days (SEM 2.48) vs. 66 (SEM1.46), P =0.002]. CONCLUSIONS: In 2020, there was no difference in screening studies for lung and breast cancer but there was a decrease in new diagnoses. Although there were fewer colonoscopies performed in 2020, there was no change in new colorectal cancer diagnoses. Despite changes in guidelines during the pandemic, the time-to-treatment for lung cancer was shorter and was unchanged for colorectal and breast cancer. These findings highlight the importance of continuing care for a vulnerable patient population despite a pandemic.

Minimally invasive combined approach robotic thymectomy and transcervical total thyroidectomy.

Myasthenia gravis (MG) is the most common autoimmune disorder affecting the neuromuscular junction in the USA. It is not uncommon for these patients to have concomitant autoimmune diseases including autoimmune thyroid disease. We describe here our method of performing a reproducible robotically assisted one-stage thymectomy and thyroidectomy. An African-American woman presented to our institution with a medical history of hypertension, morbid obesity, type 2 diabetes mellitus, symptomatic MG and symptomatic non-toxic substernal multinodular goitre. A one-stage minimally invasive right-sided robotic radical thymectomy and a transcervical total thyroidectomy with excision of the substernal goitre was successfully performed. The treatment of thyroid and thymus pathologies varies drastically from medical observation to surgery. This combined approach surgery clearly benefits the patient by offering similar operative time, fewer operative and postoperative recovery experiences, decreased anaesthesia risks associated with MG patients through fewer intubations, and a faster return to baseline function.

The State of Racial and Gender Diversity in Cardiothoracic Surgery Training.

BACKGROUND: The field of cardiothoracic surgery has been striving to increase its gender and racial diversity. We sought to examine changes in gender and racial diversity in cardiothoracic fellowships and integrated residencies in the past decade. METHODS: Accreditation Council for Graduate Medical Education data were obtained from 2011 to 2019. Linear trends were assessed for year-by-year data. Average percentages of women and underrepresented minorities were then calculated in 3-year intervals. Intervals were compared with Student's t test and χ2 tests. RESULTS: There was no statistically significant increase in percent female trainees in cardiothoracic fellowships (18.5% to 22.1%, P = .10) or integrated residencies (22.8% to 27.8%, P = .17), despite a significant increase in percent female applicants to fellowship (18.2% to 35.3%, P < .01) and integrated residency (8.9% to 33.0%, P < .01). Cardiothoracic fellowships had no increase in underrepresented minority trainees (8.3% to 9.4%, P = .48). Underrepresented minority trainees in integrated residencies increased from 2.7% to 6.9% (P = .03). Although there was no significant increase in underrepresented minority applicants to fellowships (10.2% to 11.3%, P = .66), the percent of underrepresented minority applicants to integrated residencies increased from 13.1% to 19.3% (P < .01). CONCLUSIONS: Cardiothoracic surgery training programs are attracting more female applicants, but that has not yet resulted in a higher percentage of female trainees. Although percentages of underrepresented minorities increased among integrated residency applicants and trainees, they remain low compared with other specialties. These data reflect positive changes but also highlight that much remains to be done to increase diversity in cardiothoracic surgery training.

COVID-19's impact on lung tissue: A case report.

INTRODUCTION: The novel coronavirus has spread globally, however, there continues to be little information regarding management, treatment, and complications encountered by infected patients. Prior to COVID-19, guidelines had been well established for managing empyema, however, evidence is lacking for such patients possessing a COVID-19 infection. In the spirit of collaborative knowledge, we endeavor to present a COVID-19 case from our tertiary care institution. CASE PRESENTATION: A 59-year-old Caucasian male with a past medical history of chronic obstructive pulmonary disease and hypertension was transferred to our hospital for escalation of care of COVID pneumonia. Pharmaceutical treatment included an IL-6 inhibitor (tocilizumab). The patient's hospital course was complicated by superimposed bacterial pneumonia with development of a loculated pleural empyema. On day 57, a left anterolateral muscle-sparing thoracotomy and complete pulmonary decortication was performed. The patient made a successful recovery. CLINICAL DISCUSSION: This patient's vascular dysfunction associated with shunting secondary to pulmonary microthrombi, provides rationale for the liberal use of therapeutic anticoagulation in COVID patients. The superimposed bacterial pneumonia raises concerns over the use of tocilizumab in COVID-19 patients. It is necessary to understand whether current guidelines will need to be amended for the treatment of coagulopathies to avoid pulmonary vascular dysfunction. CONCLUSION: Thoracic surgery can be carried out safely, both for patients and practitioners, during the pandemic. Microvascular occlusions within the pulmonary vasculature contribute to the severe hypoxia and need for anticoagulation in severe COVID-19 cases. Clinical pathways for common clinical presentations, such as empyema, may need to be re-evaluated during this global crisis.

Blocking the IL-1 receptor reduces cardiac transplant ischemia and reperfusion injury and mitigates CMV-accelerated chronic rejection.

Ischemia-reperfusion injury (IRI) is an important risk factor for accelerated cardiac allograft rejection and graft dysfunction . Utilizing a rat heart isogeneic transplant model, we identified inflammatory pathways involved in IRI in order to identify therapeutic targets involved in disease. Pathway analyses identified several relevant targets, including cytokine signaling by the IL-1 receptor (IL-1R) pathway and inflammasome activation. To investigate the role of IL-1R signaling pathways during IRI, we treated syngeneic cardiac transplant recipients at 1-hour posttransplant with Anakinra, a US Food and Drug Administration (FDA)-approved IL-1R antagonist; or parthenolide, a caspase-1 and nuclear factor kappa-light-chain-enhancer of activated B cells inhibitor that blocks IL-1ß maturation. Both Anakinra and parthenolide significantly reduced graft inflammation and cellular recruitment in the treated recipients relative to nontreated controls. Anakinra treatment administered at 1-hour posttransplant to recipients of cardiac allografts from CMV-infected donors significantly increased the time to rejection and reduced viral loads at rejection. Our results indicate that reducing IRI by blocking IL-1Rsignaling pathways with Anakinra or inflammasome activity with parthenolide provides a promising approach for extending survival of cardiac allografts from CMV-infected donors.

The transverse aortic constriction heart failure animal model: a systematic review and meta-analysis.

The transverse aortic constriction (TAC) model is frequently used to study adverse cardiac remodeling upon pressure overload. We set out to define the most important characteristics that define the degree of cardiac remodeling in this model. A systematic review and meta-analyses were performed on studies using the TAC mouse/rat model and reporting echocardiographic outcome parameters. We included all animal studies in which a constriction around the transverse aorta and at least one of the predefined echocardiography or MRI outcome parameters were assessed. A total of 502 articles and > 3000 wild-type, untreated animals undergoing TAC were included in this study and referenced to a control group. The duration of aortic constriction correlated to the degree of adverse remodeling. However, the mouse data is strongly biased by the preferential use of male C57Bl/6 mice (66% of studies). Furthermore, mostly ketamine/xylazine anesthetics, 27G needle constriction, and silk sutures are used. Nonetheless, despite the homogeneity in experimental design, the model contained a substantial degree of heterogeneity in the functional outcome measures. When looking at study quality, only 12% reported randomization, 23% mentioned any sort of blinding, 25% adequately addressed the outcomes, and an amazingly low percentage (2%) showed sample size calculation. Meta-analyses did not detect specific study characteristics that explained the heterogeneity in the reported outcome measures, however this might be related to the strong bias towards the use of specific mouse lines, sex as well as age or to poor reporting of characteristics of study quality.

Macrophage depletion of CMV latently infected donor hearts ameliorates recipient accelerated chronic rejection.

Cytomegalovirus (CMV) infection is linked to acceleration of solid organ transplant vascular sclerosis (TVS) and chronic rejection (CR). Donor latent CMV infection increases cardiac-resident macrophages and T cells leading to increased inflammation, promoting allograft rejection. To investigate the role of cardiac-resident passenger macrophages in CMV-mediated TVS/CR, macrophages were depleted from latently ratCMV (RCMV)-infected donor allografts prior to transplantation. Latently RCMV-infected donor F344 rats were treated with clodronate, PBS, or control liposomes 3 days prior to cardiac transplant into RCMV-naïve Lewis recipients. Clodronate treatment significantly increased graft survival from post-operative day (POD)61 to POD84 and decreased TVS at rejection. To determine the kinetics of the effect of clodronate treatment's effect, a time study revealed that clodronate treatment significantly decreased macrophage infiltration into allograft tissues as early as POD14; altered allograft cytokine/chemokine protein levels, fibrosis development, and inflammatory gene expression profiles. These findings support our hypothesis that increased graft survival as a result of allograft passenger macrophage depletion was in part a result of altered immune response kinetics. Depletion of donor macrophages prior to transplant is a strategy to modulate allograft rejection and reduce TVS in the setting of CMV + donors transplanted into CMV naïve recipients.

Rat Cytomegalovirus Virion-Associated Proteins R131 and R129 Are Necessary for Infection of Macrophages and Dendritic Cells.

Cytomegalovirus (CMV) establishes persistent, latent infection in hosts, causing diseases in immunocompromised patients, transplant recipients, and neonates. CMV infection modifies the host chemokine axis by modulating chemokine and chemokine receptor expression and by encoding putative chemokine and chemokine receptor homologues. The viral proteins have roles in cellular signaling, migration, and transformation, as well as viral dissemination, tropism, latency and reactivation. Herein, we review the contribution of CMV-encoded chemokines and chemokine receptors to these processes, and further elucidate the viral tropism role of rat CMV (RCMV) R129 and R131. These homologues of the human CMV (HCMV)-encoded chemokines UL128 and UL130 are of particular interest because of their dual role as chemokines and members of the pentameric entry complex, which is required for entry into cell types that are essential for viral transmission and dissemination. The contributions of UL128 and UL130 to acceleration of solid organ transplant chronic rejection are poorly understood, and are in need of an effective in vivo model system to elucidate the phenomenon. We demonstrated similar molecular entry requirements for R129 and R131 in the rat cells, as observed for HCMV, and provided evidence that R129 and R131 are part of the viral entry complex required for entry into macrophages, dendritic cells, and bone marrow cells.

Effect of stent implantation on blood pressure control in adults with coarctation of the aorta.

BACKGROUND: Stenting of coarctation of the aorta (CoA) generally results in good angiographic results and a decrease in transcoarctation pressure gradient. However, effect on blood pressure control is less clear. The goal of the current retrospective analysis was to investigate the effects of CoA stenting on blood pressure control. METHODS: A retrospective analysis was conducted in consecutive adult patients with a CoA who underwent a percutaneous intervention at one of the three participating hospitals. Measurements included office blood pressure, invasive peak-to-peak systolic pressure over the CoA, diameter of the intima lumen at the narrowest part of the CoA and use of medication. The follow-up data were obtained, based on the most recent examination date. RESULTS: There were 26 native CoA and 17 recurrent CoAs (total n = 43). Seven of them underwent two procedures. Mean peak-to-peak gradient decreased from 27 mmHg to 3 mmHg (p < 0.001), and minimal diameter increased from a mean of 11 mm to 18 mm (p < 0.001). Mean systolic blood pressure decreased from 151 ±â€¯18 mmHg to 135 ±â€¯19 mmHg at first follow-up of 3.8 ±â€¯1.9 months and 137 ±â€¯22 mmHg at latest follow-up of 19.5 ±â€¯10.9 months (p = 0.001 and p = 0.009, compared to baseline, respectively). The total number of hypertensive patients decreased from 74% to 27% at latest follow-up. No significant change in antihypertensive medication was observed. CONCLUSION: A clinically significant decrease in systolic blood pressure of approximately 16 mmHg was shown after (re)intervention in CoA patients, which sustained at follow-up. This sustained decrease of blood pressure can be expected to lead to less future adverse cardiovascular events.

Impact of center volume and the adoption of laparoscopic donor nephrectomy on outcomes in pediatric kidney transplantation.

Reports for pediatric kidney transplant recipients suggested better outcomes for ODN compared to LDN. Contemporary outcomes stratified by donor type and center volume have not been evaluated in a national dataset. UNOS data (2000-2014) were analyzed for pediatric living donor kidney transplant recipients. The primary outcome was GF; secondary outcomes were DGF, rejection, and patient survival. Live donor nephrectomies for pediatric recipients decreased 30% and transitioned from ODN to LDN. GF rates did not differ for ODN vs LDN (P = .24). GF was lowest at high volume centers (P < .01). Donor operative approach did not contribute to GF. LDN was associated with less rejection than ODN (OR 0.66, CI 0.5-0.87, P < .01). Analysis of the 0- to 5-yr recipient group showed no effect of ODN vs LDN on GF or rejection. For the contemporary era, there was no association between DGF and LDN in the 0- to 5-yr group (OR 1.12, CI 0.67-1.89, P = .67). Outcomes of kidney transplants in pediatric recipients following LDN have improved since its introduction and LDN should be the approach for live donor nephrectomy regardless of recipient age. The association between case volume and improved outcomes highlights future challenges in organ transplantation.

Early post-approval experience with transcatheter aortic valve replacement in the USA.

BACKGROUND: Transcatheter aortic valve replacement (TAVR) is changing the treatment of aortic stenosis. We compared cost and clinical outcomes of TAVR versus surgical aortic valve repair (SAVR) in the real-world setting since USA TAVR approval in 2012. METHODS: The Nationwide Inpatient Sample (NIS) dataset was analyzed by quarter (June 2012 to December 2014). Patients (>65 years old) undergoing TAVR or SAVR were identified and risk stratified based on APR-DRG Mortality risk score. Outcomes were in-hospital mortality, length of stay (LOS), discharge location, and hospitalization cost. RESULTS: TAVR cases per quarter increased from 1900 to 5445 over the study period. TAVR patients were older and had more comorbidities (P<0.001). TAVR patients had longer LOS (8 vs. 7 days; P<0.001), were less likely to discharge to home (67% vs. 73%; P<0.001), had higher inpatient mortality (5.5% vs. 0.69%; P<0.001) and overall hospital cost ($ 227,985 vs. $ 148,019; P<0.001) than SAVR patients. On multivariate analysis TAVR was associated with increased cost (ß=0.42; P<0.001) and increased mortality (OR=5.228, CI: 3.508-7.791; P<0.001) but not associated with increased LOS (ß=0.297; P=0.078) or discharge to facility (OR=1.004, CI: 0.833-1.213; P=0.960). In the last two quarters of 2014 there was no difference between TAVR and SAVR LOS, however TAVR cost did not decrease over the study period. CONCLUSIONS: TAVR patients represented a sicker population, however LOS and discharge location outcomes were equivalent to SAVR. TAVR remained significantly more expensive across all risk groups and cost did not fall over the course of the study.

Cirrhosis increases mortality and splenectomy rates following splenic injury.

BACKGROUND: Cirrhosis may be a risk factor for mortality following blunt splenic injury (BSI) and it predicts the need for an operative intervention. METHODS: We performed a case-control study at 3 level 1 trauma centers. Comparisons were made with chi-square test, Wilcoxon rank-sum test, and binary logistic regression, and stratified by propensity for splenectomy. Data are presented as odds ratios (ORs) and 95% confidence intervals (95% CIs). RESULTS: Mortality was 27% (21/77) and cirrhosis was a strong risk factor for death (OR 8.8, 95% CI 3.7 to 21.1). Compared with controls, cirrhosis was an independent risk factor for splenectomy (OR 5.4, 95% CI 2.5 to 11.5), and only splenic injury grade was associated with splenectomy (OR 2.2, 95% CI 1.3 to 3.6). Only admission model for end-stage liver disease was independently associated with mortality after an operation (OR 1.7, 95% CI 1.1 to 2.8). After propensity score matching, we found no association between splenectomy and mortality in cirrhotic patients. CONCLUSION: Cirrhosis dramatically increases mortality and the odds of an operative intervention in BSI patients with pre-existing cirrhosis, and BSI requires vigilant attention and early intervention should be considered.

Phase I study of the CD40 agonist antibody CP-870,893 combined with carboplatin and paclitaxel in patients with advanced solid tumors.

CD40 is a cell-surface molecule that critically regulates immune responses. CP-870,893 is a fully human, CD40-specific agonist monoclonal antibody (mAb) exerting clinical antineoplastic activity. Here, the safety of CP-870,893 combined with carboplatin and paclitaxel was assessed in a Phase I study. Patients with advanced solid tumors received standard doses of paclitaxel and carboplatin on day 1 followed by either 0.1 mg/Kg or 0.2 mg/Kg CP-870,893 on day 3 (Schedule A) or day 8 (Schedule B), repeated every 21 d. The primary objective was to determine safety and maximum-tolerated dose (MTD) of CP-870,893. Secondary objectives included the evaluation of antitumor responses, pharmacokinetics and immune modulation. Thirty-two patients were treated with CP-870,893, 16 patients on each schedule. Two dose-limiting toxicities were observed (grade 3 cytokine release and transient ischemic attack), each at the 0.2 mg/Kg dose level, which was estimated to be the MTD. The most common treatment-related adverse event was fatigue (81%). Of 30 evaluable patients, 6 (20%) exhibited partial responses constituting best responses as defined by RECIST. Following CP-870,893 infusion, the peripheral blood manifested an acute depletion of B cells associated with upregulation of immune co-stimulatory molecules. T-cell numbers did not change significantly from baseline, but transient tumor-specific T-cell responses were observed in a small number of evaluable patients. The CD40 agonist mAb CP-870,893, given on either of two schedules in combination with paclitaxel and carboplatin, was safe for patients affected with advanced solid tumors. Biological and clinical responses were observed, providing a rationale for Phase II studies.

Clinical effect and safety profile of recombinant human lysosomal acid lipase in patients with cholesteryl ester storage disease.

UNLABELLED: Cholesteryl ester storage disease (CESD), an inherited deficiency of lysosomal acid lipase (LAL), is an underappreciated cause of progressive liver disease with no approved therapy. Presenting features include dyslipidemia, elevated transaminases, and hepatomegaly. To assess the clinical effects and safety of the recombinant human LAL, sebelipase alfa, nine patients received four once-weekly infusions (0.35, 1, or 3 mg·kg(-1) ) in LAL-CL01, which is the first human study of this investigational agent. Patients completing LAL-CL01 were eligible to enroll in the extension study (LAL-CL04) in which they again received four once-weekly infusions of sebelipase alfa (0.35, 1, or 3 mg·kg(-1) ) before transitioning to long-term every-other-week infusions (1 or 3 mg·kg(-1) ). Sebelipase alfa was well tolerated, with mostly mild adverse events unrelated to sebelipase alfa. No antidrug antibodies were detected. Transaminases decreased in patients in LAL-CL01 and increased between studies. In seven patients receiving ongoing sebelipase alfa treatment in LAL-CL04, the mean ± standard deviation (SD) decreases for alanine transaminase and aspartate aminotransferase at week 12 compared to the baseline values in LAL-CL01 were 46 ± 21 U/L (-52%) and 21 ± 14 U/L (-36%), respectively (P ≤ 0.05). Through week 12 of LAL-CL04, these seven patients also showed mean decreases from baseline in total cholesterol of 44 ± 41 mg/dL (-22%; P = 0.047), low density lipoprotein-cholesterol of 29 ± 31 mg/dL (-27%; P = 0.078), and triglycerides of 50 ± 38 mg/dL (-28%, P = 0.016) and increases in high density lipoprotein-cholesterol of 5 mg/dL (15%; P = 0.016). CONCLUSION: These data establish that sebelipase alfa, an investigational enzyme replacement, in patients with CESD is well tolerated, rapidly decreases serum transaminases, and that these improvements are sustained with long-term dosing and are accompanied by improvements in serum lipid profile.

Development of a host blood meal database: de novo sequencing of hemoglobin from nine small mammals using mass spectrometry.

We report the successful de novo sequencing of hemoglobin using a mass spectrometry-based approach combined with automatic data processing and manual validation for nine North American species with currently unsequenced genomes. The complete α and ß chain of all nine mammalian hemoglobin samples used in this study were successfully sequenced. These sequences will be appended to the existing database containing all known hemoglobins to be used for identification of the mammalian host species that provided the last blood meal for the tick vector of Lyme disease, Ixodes scapularis.

Progenitor migration to the thymus and T cell lineage commitment.

T cells developing in the thymus are ultimately derived from bone marrow (BM) hematopoietic stem cells (HSCs). An understanding of the developmental steps between HSCs and T cells is important for gaining insight into cancers of the T lineage, improving T cell reconstitution after BM transplantation, and also to help ameliorate immunological defects in aging. In this article, we summarize our current understanding of the inter-related fields of early T cell development and thymic aging, and briefly discuss major unresolved questions in this field.

Notch signaling augments T cell responsiveness by enhancing CD25 expression.

Notch receptors signal through a highly conserved pathway to influence cell fate decisions. Notch1 is required for T lineage commitment; however, a role for Notch signaling has not been clearly defined for the peripheral T cell response. Notch gene expression is induced, and Notch1 is activated in primary CD4(+) T cells following specific peptide-Ag stimulation. Notch activity contributes to the peripheral T cell response, as inhibition of endogenous Notch activation decreases the proliferation of activated T cells in a manner associated with the diminished production of IL-2 and the expression of the high affinity IL-2R (CD25). Conversely, forced expression of a constitutively active Notch1 in primary T cells results in increased surface expression of CD25, and renders these cells more sensitive to both cognate Ag and IL-2, as measured by cell division. These data suggest an important role for Notch signaling during CD4(+) T cell responses, which operates through augmenting a positive feedback loop involving IL-2 and its high affinity receptor.