Although the concept that cancers originate from stem cells (SC) is becoming scientifically accepted, mechanisms by which SC contribute to tumor initiation and progression are largely unknown. For ...colorectal cancer (CRC), investigation of this problem has been hindered by a paucity of specific markers for identification and isolation of SC from normal and malignant colon. Accordingly, aldehyde dehydrogenase 1 (ALDH1) was investigated as a possible marker for identifying colonic SC and for tracking them during cancer progression. Immunostaining showed that ALDH1(+) cells are sparse and limited to the normal crypt bottom, where SCs reside. During progression from normal epithelium to mutant (APC) epithelium to adenoma, ALDH1(+) cells increased in number and became distributed farther up the crypt. CD133(+) and CD44(+) cells, which are more numerous and broadly distributed in normal crypts, showed similar changes during tumorigenesis. Flow cytometric isolation of cancer cells based on enzymatic activity of ALDH (Aldefluor assay) and implantation of these cells in nonobese diabetic-severe combined immunodeficient mice (a) generated xenograft tumors (Aldefluor(-) cells did not), (b) generated them after implanting as few as 25 cells, and (c) generated them dose dependently. Further isolation of cancer cells using a second marker (CD44(+) or CD133(+) serially) only modestly increased enrichment based on tumor-initiating ability. Thus, ALDH1 seems to be a specific marker for identifying, isolating, and tracking human colonic SC during CRC development. These findings also support our original hypothesis, derived previously from mathematical modeling of crypt dynamics, that progressive colonic SC overpopulation occurs during colon tumorigenesis and drives CRC development.
Patients with chronic ulcerative colitis are at increased risk of developing colorectal cancer. Although current hypotheses suggest that sporadic colorectal cancer is due to inability to control ...cancer stem cells, the cancer stem cell hypothesis has not yet been validated in colitis-associated cancer. Furthermore, the identification of the colitis to cancer transition is challenging. We recently showed that epithelial cells with the increased expression of aldehyde dehydrogenase in sporadic colon cancer correlate closely with tumor-initiating ability. We sought to determine whether ALDH can be used as a marker to isolate tumor-initiating populations from patients with chronic ulcerative colitis. We used fluorescence-activated cell sorting to identify precursor colon cancer stem cells from colitis patients and report both their transition to cancerous stem cells in xenografting studies as well as their ability to generate spheres in vitro. Similar to sporadic colon cancer, these colitis-derived tumors were capable of propagation as sphere cultures. However, unlike the origins of sporadic colon cancer, the primary colitic tissues did not express any histologic evidence of dysplasia. To elucidate a potential mechanism for our findings, we compared the stroma of these different environments and determined that at least one paracrine factor is up-regulated in the inflammatory and malignant stroma compared with resting, normal stroma. These data link colitis and cancer identifying potential tumor-initiating cells from colitic patients, suggesting that sphere and/or xenograft formation will be useful to survey colitic patients at risk of developing cancer.
Airway rapid response (ARR) teams can be compiled of anesthesiologists, intensivists, otolaryngologists, general and thoracic surgeons, respiratory therapists, and nurses. The optimal composition of ...an ARR team is unknown but considered to be resource intensive. We sought to determine the type of technical procedures performed during an ARR activation to inform team composition.
A large urban quaternary academic medical center retrospective review (2016-2019) of adult ARR patients was performed. Analysis included ARR demographics, patient characteristics, characteristics of preexisting tracheostomies, incidence of concomitant conditions, and procedures completed during an ARR event.
A total of 345 ARR patients with a median age of 60 years (interquartile range, 47-69 years) and a median time to ARR conclusion of 28 minutes (interquartile range, 14-47 minutes) were included. About 41.7% of the ARR had a preexisting tracheostomy. Overall, there were 130 procedures completed that can be performed by a general surgeon in addition to the 122 difficult intubations. These procedures included recannulation of a tracheostomy, operative intervention, new emergent tracheostomy or cricothyroidotomy, thoracostomy tube placement, initiation of extracorporeal membrane oxygenation, and pericardiocentesis.
Highly technical procedures are common during an ARR, including procedures related to tracheostomies. Surgeons possess a comprehensive skill set that is unique and comprehensive with respect to airway emergencies. This distinctive skill set creates an important role within the ARR team to perform these urgent technical procedures.
Epidemiologic/prognostic, level III.
Background. International travel poses a risk of destination-specific illness and may contribute to the global spread of infectious diseases. Despite this, little is known about the health ...characteristics and pretravel healthcare of US international travelers, particularly those at higher risk of travel-associated illness. Methods. We formed a national consortium (Global TravEpiNet) of 18 US clinics registered to administer yellow fever vaccination. We collected data regarding demographic and health characteristics, destinations, purpose of travel, and pretravel healthcare from 13 235 international travelers who sought pretravel consultation at these sites from January 2009 through January 2011. Results. The destinations and itineraries of Global TravEpiNet travelers differed from those of the overall population of US international travelers. The majority of Global TravEpiNet travelers were visiting low- or lower-middle-income countries, and Africa was the most frequently visited region. Seventy-five percent of travelers were visiting malaria-endemic countries, and 38% were visiting countries endemic for yellow fever. Fifty-nine percent of travelers reported ≥ 1 medical condition. Atovaquone/proguanil was the most commonly prescribed antimalarial drug, and most travelers received an antibiotic for self-treatment of travelers' diarrhea. Hepatitis A and typhoid were the most frequently administered vaccines. Conclusions. Data from Global TravEpiNet provide insight into the characteristics and pretravel healthcare of US international travelers who are at increased risk of travel-associated illness due to itinerary, purpose of travel, or existing medical conditions. Improved understanding of this epidemiologically significant population may help target risk-reduction strategies and interventions to limit the spread of infections related to global travel.
BackgroundVenous thromboembolism (VTE) after an inferior vena cava (IVC) injury is a devastating complication. Current practice involves variable use of anticoagulation and antiplatelet (AC/AP) ...agents. We hypothesized that AC/AP can reduce the incidence of VTE and that delayed institution of AC/AP is associated with increased VTE events.MethodsWe retrospectively reviewed IVC injuries cared for at a large urban adult academic level 1 trauma center between January 1, 2008 and December 31, 2020, surviving 72 hours. Patient demographics, injury mechanism, surgical repair, type and timing of AC, and type and timing of VTE events were characterized. Postoperative AC status during hospital course before an acute VTE event was delineated by grouping patients into four categories: full, prophylactic, prophylactic with concomitant AP, and none. The primary outcome was the incidence of an acute VTE event. IVC ligation was excluded from analysis.ResultsOf the 76 patients sustaining an IVC injury, 26 were included. The incidence of a new deep vein thrombosis distal to the IVC injury and a new pulmonary embolism was 31% and 15%, respectively. The median onset of VTE was 5 days (IQR 1–11). Four received full AC, 10 received prophylactic AC with concomitant AP, 8 received prophylactic AC, and 4 received no AC/AP. New VTE events occurred in 0.0% of full, in 30.0% of prophylactic with concomitant AP, in 50.0% of prophylactic, and in 50.0% without AC/AP. There was no difference in baseline demographics, injury mechanisms, surgical interventions, and bleeding complications.DiscussionThis is the first study to suggest that delay and degree of antithrombotic initiation in an IVC-injured patient may be associated with an increase in VTE events. Consideration of therapy initiation should be performed on hemostatic stabilization. Future studies are necessary to characterize the optimal dosing and temporal timing of these therapies.Level of evidenceTherapeutic, level 3.
To develop and validate VisCap, a software program targeted to clinical laboratories for inference and visualization of germ-line copy-number variants (CNVs) from targeted next-generation sequencing ...data.
VisCap calculates the fraction of overall sequence coverage assigned to genomic intervals and computes log2 ratios of these values to the median of reference samples profiled using the same test configuration. Candidate CNVs are called when log2 ratios exceed user-defined thresholds.
We optimized VisCap using 14 cases with known CNVs, followed by prospective analysis of 1,104 cases referred for diagnostic DNA sequencing. To verify calls in the prospective cohort, we used droplet digital polymerase chain reaction (PCR) to confirm 10/27 candidate CNVs and 72/72 copy-neutral genomic regions scored by VisCap. We also used a genome-wide bead array to confirm the absence of CNV calls across panels applied to 10 cases. To improve specificity, we instituted a visual scoring system that enabled experienced reviewers to differentiate true-positive from false-positive calls with minimal impact on laboratory workflow.
VisCap is a sensitive method for inferring CNVs from targeted sequence data from targeted gene panels. Visual scoring of data underlying CNV calls is a critical step to reduce false-positive calls for follow-up testing.
Recent advances have demonstrated substantial benefits from learning with both generative and discriminative parameters. On the one hand, generative approaches address the estimation of the ...parameters of the joint distribution—
P
(
y
,
x
)
, which for most network types is very computationally
efficient
(a notable exception to this are Markov networks) and on the other hand, discriminative approaches address the estimation of the parameters of the posterior distribution—and, are more
effective
for classification, since they fit
P
(
y
|
x
)
directly. However, discriminative approaches are less computationally efficient as the normalization factor in the conditional log-likelihood precludes the derivation of closed-form estimation of parameters. This paper introduces a new discriminative parameter learning method for Bayesian network classifiers that combines in an elegant fashion parameters learned using both generative and discriminative methods. The proposed method is discriminative in nature, but uses estimates of generative probabilities to speed-up the optimization process. A second contribution is to propose a simple framework to characterize the parameter learning task for Bayesian network classifiers. We conduct an extensive set of experiments on 72 standard datasets and demonstrate that our proposed discriminative parameterization provides an efficient alternative to other state-of-the-art parameterizations.
Variant interpretation depends on accurate annotations using biologically relevant transcripts. We have developed a systematic strategy for designating primary transcripts and have applied it to 109 ...hearing loss–associated genes that were divided into three categories. Category 1 genes (n = 38) had a single transcript; category 2 genes (n = 33) had multiple transcripts, but a single transcript was sufficient to represent all exons; and category 3 genes (n = 38) had multiple transcripts with unique exons. Transcripts were curated with respect to gene expression reported in the literature and the Genotype-Tissue Expression Project. In addition, high-frequency loss-of-function variants in the Genome Aggregation Database and disease-causing variants in ClinVar and the Human Gene Mutation Database across the 109 genes were queried. These data were used to classify exons as clinically significant, insignificant, or of uncertain significance. Interestingly, 6% of all exons, containing 124 reportedly disease-causing variants, were of uncertain significance. Finally, we used exon-level next-generation sequencing quality metrics generated at two clinical laboratories and identified a total of 43 technically challenging exons in 20 different genes that had inadequate coverage and/or homology issues that might lead to false-variant calls. We have demonstrated that transcript analysis plays a critical role in accurate clinical variant interpretation.
The hedgehog pathway has been implicated in the tumorigenesis, tumor progression, and metastasis of numerous human cancers. We generated the first fully human hedgehog antibody MEDI-5304 and ...characterized its antitumor activity and preclinical toxicology. MEDI-5304 bound sonic hedgehog (SHH) and Indian hedgehog (IHH) with low picomolar affinity and neutralized SHH and IHH activity in cellular mGLI1 reporter assays. The antibody inhibited transcription of hedgehog target genes and osteoblast differentiation of C3H10T1/2 cells. We evaluated the activity of MEDI-5304 in vivo in model systems that allowed us to evaluate two primary hypotheses of hedgehog function in human cancer, paracrine signaling between tumor and stromal cells and cancer stem cell (CSC) self-renewal. MEDI-5304 displayed robust pharmacodynamic effects in stromal cells that translated to antitumor efficacy as a single agent in an HT-29/MEF coimplantation model of paracrine hedgehog signaling. MEDI-5304 also improved responses to carboplatin in the HT-29/MEF model. The antibody, however, had no effect as a single agent or in combination with gemcitabine on the CSC frequency or growth of several primary pancreatic cancer explant models. These findings support the conclusion that hedgehog contributes to tumor biology via paracrine tumor-stromal signaling but not via CSC maintenance or propagation. Finally, the only safety study finding associated with MEDI-5304 was ondontodysplasia in rats. Thus, MEDI-5304 represents a potent dual hedgehog inhibitor suitable for continued development to evaluate efficacy and safety in human patients with tumors harboring elevated levels of SHH or IHH.
Technetium, uranium and neptunium may all occur in the environment in more than one oxidation state (IV or VII, IV or VI and IV or V respectively). The surface of mackinawite, the first-formed iron ...sulfide phase in anoxic conditions, can promote redox changes so a series of laboratory experiments were carried out to explore the interactions of Tc, U and Np with this mineral. The products of reaction were characterised using X-ray absorption spectroscopy. Technetium, added as TcO
4
−, is reduced to oxidation state IV and forms a TcS
2-like species. On oxidation of the mackinawite in air to form goethite, Tc remains in oxidation state IV but in an oxide, rather than a sulfide environment. At low concentrations, uranium forms uranyl surface complexes on oxidised regions of the mackinawite surface but at higher concentrations, the uranium promotes surface oxidation and forms a mixed oxidation state oxide phase. Neptunium is reduced to oxidation IV and forms a surface complex with surface sulfide ions. The remainder of the Np coordination sphere is filled with water molecules or hydroxide ions.
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