Sites Of Extravasation Research Articles

Stent-graft implantation for late postpancreatectomy hemorrhage after pancreatoduodenectomy

PurposePostpancreatectomy hemorrhage (PPH) is a life-threatening complication after pancreatoduodenectomy. Stent-graft implantation is an emerging treatment option for PPH. This study reports the outcome of PPH treated with stent-graft implantation. MethodsThis was a single-center, retrospective study. Between April 2020 and December 2023, 1723 pancreatectomy cases were collected while we screened 12 cases of PPH after pancreatoduodenectomy treated with stent-graft implantation. Patients’ medical and radiologic images were retrospectively reviewed. Technical and clinical success, complications, and stent-graft patency were evaluated. Continuous data are reported as means ± SD when normally distributed or as median (Q1, Q3) when the data is non-normal distributed. Categorical data are reported as n (%). A p value < 0.05 was considered statistically significant. Kaplan-Meier estimates were used for stent patency and patients’ survival. ResultsPancreatic fistula was identified in 6 cases (50.0%), and pseudoaneurysm was identified in 3 cases (25.0%), including pancreatic fistula together with pseudoaneurysm in 1 case (8.3%). All pseudoaneurysm or contrast extravasation sites were successfully excluded with patent distal perfusion, thus technical success was achieved in all cases. The overall survival rate at 6 months and 1 year was 91.7% and 78.6%, respectively. One patient had herniation of the small intestine into the thoracic cavity, which caused a broad thoracic and abdominal infection and died during hospitalization. Rebleeding occurred at the gastroduodenal artery stump in 1 case after stent-graft implantation for the splenic artery and was successfully treated with another stent-graft implantation. Two cases of asymptomatic stent-graft occlusion were observed at 24.6 and 26.3 after the operation, respectively. ConclusionsWith suitable anatomy, covered stent-graft implantation is an effective and safe treatment option for PPH with various bleeding sites and causes.

Spontaneous intercostal artery bleeding occurring simultaneously in numerous vessels during antithrombotic therapy with mechanical circulatory support: a case report

BackgroundIntercostal artery bleeding often occurs in a single vessel; in rare cases, it can occur in numerous vessels, making it more difficult to manage.Case presentationA 63-year-old Japanese man was admitted to the emergency department owing to sudden chest and back pain, dizziness, and nausea. Emergency coronary angiography revealed myocardial infarction secondary to right coronary artery occlusion. After intra-aortic balloon pumping, percutaneous coronary intervention was performed in the right coronary artery. At 12 hours following percutaneous coronary intervention, the patient developed new-onset left anterior chest pain and hypotension. Contrast-enhanced computed tomography revealed 15 sites of contrast extravasation within a massive left extrapleural hematoma. Emergency angiography revealed contrast leakage in the left 6th to 11th intercostal arteries; hence, transcatheter arterial embolization was performed. At 2 days after transcatheter arterial embolization, his blood pressure subsequently decreased, and contrast-enhanced computed tomography revealed the re-enlargement of extrapleural hematoma with multiple sites of contrast extravasation. Emergency surgery was performed owing to persistent bleeding. No active arterial hemorrhage was observed intraoperatively. Bleeding was observed in various areas of the chest wall, and an oxidized cellulose membrane was applied following ablation and hemostasis. The postoperative course was uneventful.ConclusionWe report a case of spontaneous intercostal artery bleeding occurring simultaneously in numerous vessels during antithrombotic therapy with mechanical circulatory support that was difficult to manage. As bleeding from numerous vessels may occur during antithrombotic therapy, even without trauma, appropriate treatments, such as transcatheter arterial embolization and surgery, should be selected in patients with such cases.

Mechanism of Spontaneous Intracerebral Hemorrhage Formation: An Anatomical Specimens-Based Study

Background:Despite advances in understanding various risk and prognostic factors, spontaneous intracerebral hemorrhage is connected to very high morbidity and mortality, while the therapy is mainly supportive. Understanding of the pathophysiology of initial hematoma expansion is limited due to insufficient clinical data and lack of a suitable animal model.Methods:We injected 40 anatomic specimens of the basal ganglia with contrast medium, scanned them with a micro-computed tomography scanner and analyzed the results of radiological studies, direct and histological examinations.Results:In 9 cases, micro-computed tomography and histological examinations revealed contrast medium extravasations mimicking intracerebral hematomas. The artificial hematomas spread both proximally and distally along the ruptured perforator and its branches in the perivascular spaces and detached the branches from the adjacent neural tissue leading to destruction of the tissue and secondary extravasations. Moreover, some contrast extravasations skipped to the perivascular spaces of unruptured perforators, created further extravasation sites and aggravated the expansion of the artificial hematoma. There was no subarachnoid extension of any artificial hematoma.Conclusions:We postulate that a forming basal ganglia intracerebral hematoma spreads initially in the perivascular space, detaches the branches from the neural tissue and causes secondary bleeding. It can also skip to the perivascular space of a nearby perforator. The proposed mechanism of hematoma initiation and formation explains extent of damage to the neural tissue, variability of growth in time and space, creation of secondary bleeding sites, and limited usefulness of surgical interventions. The model is reproducible, the extent of the artificial hematoma can be easily controlled, the rupture sites of the perforating arteries can be determined, and preparation of the model does not require specialized, expensive equipment apart from the micro-computed tomography scanner.

Spatial specific delivery of combinational chemotherapeutics to combat intratumoral heterogeneity.

Hypoxia-induced intratumoral heterogeneity poses a major challenge in tumor therapy due to the varying susceptibility to chemotherapy. Moreover, the spatial distribution patterns of hypoxic and normoxic tissues makes conventional combination therapy less effective. In this study, a tumor-acidity and bioorthogonal chemistry mediated in situ size transformable nanocarrier (NP@DOXDBCO plus iCPPAN3) was developed to spatially deliver two combinational chemotherapeutic drugs (doxorubicin (DOX) and PR104A) to combat hypoxia-induced intratumoral heterogeneity. DOX is highly toxic to tumor cells in normoxia state but less toxic in hypoxia state due to the hypoxia-induced chemoresistance. Meanwhile, PR104A is a hypoxia-activated prodrug has less toxic in normoxia state. Two nanocarriers, NP@DOXDBCO and iCPPAN3, can cross-link near the blood vessel extravasation sites through tumor acidity responsive bioorthogonal click chemistry to enhance the retention of DOX in tumor normoxia. Moreover, PR104A conjugated to the small-sized dendritic polyamidoamine (PAMAM) released under tumor acidity can penetrate deep tumor tissues for hypoxic tumor cell killing. Our study has demonstrated that this site-specific combination chemotherapy is better than the traditional combination chemotherapy. Therefore, spatial specific delivery of combinational therapeutics via in situ size transformable nanocarrier addresses the challenges of hypoxia induced intratumoral heterogeneity and provides insights into the combination therapy.

Tumor-associated high endothelial venules mediate lymphocyte entry into tumors and predict response to PD-1 plus CTLA-4 combination immunotherapy.

Recruitment of lymphocytes into tumors is critical for anti-tumor immunity and efficacious immunotherapy. We show in murine models that tumor-associated high endothelial venules (TA-HEVs) are major sites of lymphocyte entry into tumors at baseline and upon treatment with anti-PD-1/anti-CTLA-4 immune checkpoint blockade (ICB). TA-HEV endothelial cells (TA-HECs) derive from post-capillary venules, co-express MECA-79+ HEV sialomucins and E/P-selectins, and are associated with homing and infiltration into tumors of various Tcell subsets. Intravital microscopy further shows that TA-HEVs are the main sites of lymphocyte arrest and extravasation into ICB-treated tumors. Increasing TA-HEC frequency and maturation increases the proportion of tumor-infiltrating stem-like CD8+ Tcells, and ameliorates ICB efficacy. Analysis of tumor biopsies from 93 patients with metastatic melanoma reveals that TA-HEVs are predictive of better response and survival upon treatment with anti-PD-1/anti-CTLA-4 combination. These studies provide critical insights into the mechanisms governing lymphocyte trafficking in cancer immunity and immunotherapy.

Small bowel hemorrhage from check point inhibitor enteritis: a case report

BackgroundThere is rising utilization of immune checkpoint inhibitors (ICI) for a growing number of metastatic malignancies. While gastrointestinal side effects of ICI are common, isolated ICI-induced enteritis leading to small bowel hemorrhage is rare.Case presentationA 71-year-old man with a previously resected right colon adenocarcinoma on atezolizumab and recently treated Clostridioides difficile presented with acute on chronic abdominal pain and non-bloody diarrhea. A CT scan revealed enteritis of the duodenum and jejunum without colitis. Initial endoscopic work-up revealed many clean-based non-bleeding duodenal ulcers to the third portion of the duodenum and normal rectosigmoid mucosa. The patient initially improved on steroids but was readmitted on day after discharge with hematochezia and hemorrhagic shock. Repeat CT showed improvement in enteritis; however, repeat push enteroscopy revealed multiple duodenal and jejunal ulcers, two with visible vessels requiring endoscopic intervention. He continued to have significant hemorrhage requiring transfusions despite IV methylprednisolone. Conventional angiogram revealed multiple sites of active extravasation, and he underwent small bowel resection and subsequent IR embolization due to persistent bleeding. He was then started on infliximab 10 mg/kg with resolution of his small bowel hemorrhage and diarrhea.ConclusionsSevere isolated ICI-enteritis is rare and can lead to clinically significant gastrointestinal hemorrhage. Patients with severe ICI-enteritis on endoscopy should be carefully monitored for steroid refractory disease for consideration of step-up therapy such as infliximab.

Platelets docking to VWF prevent leaks during leukocyte extravasation by stimulating Tie-2

AbstractNeutrophil extravasation requires opening of the endothelial barrier but does not necessarily cause plasma leakage. Leaks are prevented by contractile actin filaments surrounding the diapedesis pore, keeping this opening tightly closed around the transmigrating neutrophils. We have identified the receptor system that is responsible for this. We show that silencing, or gene inactivation, of endothelial Tie-2 results in leak formation in postcapillary venules of the inflamed cremaster muscle at sites of neutrophil extravasation, as visualized by fluorescent microspheres. Leakage was dependent on neutrophil extravasation, because it was absent upon neutrophil depletion. We identified the Cdc42 GTPase exchange factor FGD5 as a downstream target of Tie-2 that is essential for leakage prevention during neutrophil extravasation. Looking for the Tie-2 agonist and its source, we found that platelet-derived angiopoietin-1 (Angpt1) was required to prevent neutrophil-induced leaks. Intriguingly, blocking von Willebrand factor (VWF) resulted in vascular leaks during transmigration, indicating that platelets interacting with endothelial VWF activate Tie-2 by secreting Angpt1, thereby preventing diapedesis-induced leakiness.

ROLE OF NEUTROPHILS IN THE DELIVERY OF NANOPARTICLE INTO THE TUMOR

Mechanisms of liposomes and magnetic nanoparticles accumulation in the tumor tissue were shown to be associated with neutrophils. The intravital microscopy allowed to visualize the transfer of magnetic nanoparticles by neutrophils that captured these nanoparticles, while liposomes accumulate in the tissue via micro- and macroleakages appearing at sites of neutrophil extravasation.

The role of multiphase CT in patients with acute postoperative bleeding after liver transplantation.

The aim of this study was to investigate the role of multiphase computed tomography (CT) in patients with acute postoperative bleeding after liver transplantation(LT). We retrospectively analyzed multiphase CT images in 270 post-LT bleeding patients between November 2013 and December 2017, with special attention to contrast extravasation (type I, focal or stipple; type II, jet). Patients were classified into conservative management trial and primary therapeutic intervention groups by initial treatment strategy, and then conservative management trial group was subdivided into successful conservative management and conservative management failure groups. On multiphase CT, we evaluated contrast extravasation volume, rate, and patterns (focal or stipple vs. jet). The concordances of the bleeding source determined by multiphase CT to the actual bleeding source were analyzed. Of 270 patients, 134 contrast extravasation sites were identified in 116 (43.0%) patients. Most (94.8%, 146/154) of patients without contrast extravasation was successfully managed by conservative management. The mean volume and rate of contrast extravasation significantly increased in order of successful conservative management, conservative management failure, and primary therapeutic intervention groups (all p < 0.01). In subgroup analysis, jet pattern contrast extravasation was more commonly observed with conservative management failure group (p = 0.01). In addition, the change in pattern of contrast extravasation from type I to II was significantly related to the conservative management failure (OR 10.3; 95% CI 1.8-60.4; p = 0.01). There was substantial agreement in localization of bleeding source between multiphase CT and surgery or angiography (Cohen Kappa = 0.78). Multiphase CT is helpful in the assessment for need of therapeutic intervention and to determine the treatment of choice in recipient with post-LT bleeding.

A reliable grading system for prediction of hematoma expansion in intracerebral hemorrhage in the basal ganglia.

Hematoma expansion (HE) is an independent predictor of poor outcome and secondary neurological deterioration in intracerebral hemorrhage (ICH) and is associated with high morbidity and mortality. Noncontrast computed tomography (NCCT) may identify the sites of active extravasation. Therefore, we have attempted to (1) devise a reliable and easy-to-use prediction score to predict the risk of HE in ICH and (2) validate the accuracy of this grading system and perform an independent analysis of HE predictors. We included patients in whom an intracerebral hemorrhage (ICH) occurred in the basal ganglia between Jan. 2015 and Jan. 2018. These patients had undergone a baseline CT scan at Qinghai Provincial People's Hospital within 24 hours after the onset of ICH symptoms. Two observers independently assessed the presence of the island sign, blend sign, or swirl sign on an NCCT scan during patient selection. Patients underwent a baseline NCCT scan and 24-hour NCCT follow-up for analysis of HE. The accuracy of this grading system was assessed. Independent predictors of HE were identified using multivariable regression. Of 266 patients with ICH, 61 (22.93%) presented with the island sign, 63 (23.68%) presented with the blend sign, and 50 (18.80%) presented with the swirl sign. The overall incidence of HE was 37.22% (99/266). Of 125 patients (46.99%) who underwent a baseline CT scan within 6 hours of onset, 141 (53.01%) underwent a scan in 6-24 hours. Multivariable logistic regression analysis identified the hematoma volume (OR, 0.974; P = 0.042), intraventricular hemorrhage (IVH) extension (OR, 3.225; P = 0.003), time from onset to the baseline CT scan (OR, 0.986; P < 0.001), and anticoagulant use or an international normalized ratio (INR) > 1.5 (OR, 3.362; P = 0.006) as closely associated with HE. In conclusion, the grading system demonstrated reliable accuracy at predicting HE. The grading system demonstrated acceptable accuracy in an independent single-institution study. The role of the grading system in predicting HE and poor outcome in patients with ICH is significant. NCCT imaging markers may serve as key markers for HE prediction.

The CT Swirl Sign Is Associated with Hematoma Expansion in Intracerebral Hemorrhage.

Hematoma expansion is an independent determinant of poor clinical outcome in intracerebral hemorrhage. Although the "spot sign" predicts hematoma expansion, the identification requires CT angiography, which limits its general accessibility in some hospital settings. Noncontrast CT, without the need for CT angiography, may identify sites of active extravasation, termed the "swirl sign." We aimed to determine the association of the swirl sign with hematoma expansion. Patients with spontaneous intracerebral hemorrhage between 2007 and 2014 who underwent an initial and subsequent noncontrast CT at a single center were retrospectively identified. The swirl sign, on noncontrast CT, was defined as iso- or hypodensity within a hyperdense region that extended across 2 contiguous 5-mm axial CT sections. A total of 212 patients met the inclusion criteria. The swirl sign was identified in 91 patients with excellent interobserver agreement (κ = 0.87). The swirl sign was associated with larger initial hematoma (P < .001) and earlier initial CT (P < .001) and hematoma expansion (P = .028). Multivariable regression modeling demonstrated that if one assumed similar initial hematoma volume, onset-to-first scan, and time between CT scans, the median absolute hematoma growth was 5.77 mL (95% CI, 2.37-9.18 mL; P = .001) and relative growth was 35.6% (95% CI, 18.5%-52.6%; P < .001) higher in patients with the swirl sign compared with those without. The NCCT swirl sign was reliably identified and is associated with hematoma expansion. We propose that the swirl sign be included in risk stratification of intracerebral hemorrhage and considered for inclusion in clinical trials.

Effect of (18)F-fluorodeoxyglucose extravasation on time taken for tumoral uptake to reach a plateau: animal and clinical PET analyses.

The present study aimed to investigate the effect of (18)F-fluorodeoxyglucose (FDG) extravasation on the time taken for tumoral uptake to reach a plateau. For the animal experiment, FDG extravasation was conducted in the tails of HCT116 tumor-bearing xenograft mice models in three groups (no extravasation, 40% extravasation, and 80% extravasation; n=5, each). Dynamic positron emission tomography (PET) images were acquired over a period of 2h following injection. Time-activity curves for FDG in the tails and tumors were calculated. For the clinical experiment, 22 patients (male:female, 14:8; age range, 70.8±9.2years) were subjected to PET/computed tomography (PET/CT) 1h after the injection of FDG. The inclusion criteria were as follows: (1) submitted to both whole-body and subsequent regional scanning; (2) entire extravasation activity visualized in the whole-body images; (3) tumor visualized on both whole-body and additional regional images; and (4) status of tumor either confirmed by biopsy or clinically suspected for malignancy. The standardized uptake values (SUVs) of the tumors (on the whole-body and additional PET images) and extravasation sites were recorded. There were no significant differences in the time taken for tumoral uptake to reach a plateau and that to reach minimum activity at the extravasation site among the three groups of mice. However, the mean tumoral activity and activity at the extravasation site were negatively correlated at 1h post-injection. According to the clinical PET findings, the differences in SUV between the whole-body and regional images were not significantly correlated with the interval between injection of FDG and start of whole-body scanning, interval between the start of whole-body scanning and start of regional scanning, extravasation volume, maximum SUV of the extravasation site, or total activity at the extravasation site. The time taken for tumoral uptake to reach a plateau is not affected by extravasation, even at extensive degrees. Thus, in routine practice, the imaging time of approximately 60min post-injection need not be modified even if extravasation is identified. However, tumor SUV may be underestimated in cases of extravasation.

Platelets Guide Leukocytes to Their Sites of Extravasation.

Effective immune responses require the directed migration of leukocytes from the vasculature to the site of injury or infection. How immune cells “find” their site of extravasation remains largely obscure. Here, we identified a previously unrecognized role of platelets as pathfinders guiding leukocytes to their exit points in the microvasculature: upon onset of inflammation, circulating platelets were found to immediately adhere at distinct sites in venular microvessels enabling these cellular blood components to capture neutrophils and, in turn, inflammatory monocytes via CD40-CD40L-dependent interactions. In this cellular crosstalk, ligation of PSGL-1 by P-selectin leads to ERK1/2 MAPK-dependent conformational changes of leukocyte integrins, which promote the successive extravasation of neutrophils and monocytes to the perivascular tissue. Conversely, blockade of this cellular partnership resulted in misguided, inefficient leukocyte responses. Our experimental data uncover a platelet-directed, spatiotemporally organized, multicellular crosstalk that is essential for effective trafficking of leukocytes to the site of inflammation.

Platelets Direct Leukocytes to their Sites of Extravasation

BackgroundLeukocyte recruitment from the microvasculature to the site of injury or infection is a key event in the inflammatory response. Whereas the principles of this highly complex process have been elucidated in the past decades, it remained poorly understood how these immune cells can ‘find’ their site of extravasation.ObjectiveThe objective of this study was to identify the exit points of myeloid leukocytes in the inflamed microvasculature and to characterize the mechanisms underlying the recruitment of these immune cells to these sites.Materials and methodsInteractions of platelets, neutrophils, inflammatory monocytes, and endothelial cells were analyzed by multi‐color in vivo microscopy in the cremaster muscle of male CX3CR‐1GFP/+ mice (exhibiting fluorescence‐labeled monocytes) upon stimulation with CCL2. Expression profiles of adhesion and signaling molecules in the microvasculature were assessed ex vivo by confocal microscopy in cremasteric tissue whole mounts. Different in vitro assays were used to further characterize the underlying mechanisms.ResultsUpon onset of inflammation, circulating platelets immediately adhered at distinct sites in venular microvessels enabling these cellular blood components to capture neutrophils and, in turn, inflammatory monocytes via CD40‐CD40L‐dependent interactions. In this cellular crosstalk, ligation of leukocyte PSGL‐1 by P‐selectin initiates conformational changes in surface‐expressed leukocyte integrins via ERK1/2 MAPK which subsequently promote the successive extravasation of neutrophils and inflammatory monocytes to the perivascular tissue. Conversely, blockade of this cellular partnership resulted in misguided, inefficient leukocyte responses.ConclusionHere, we report a previously unrecognized role of platelets as pathfinders navigating neutrophils and inflammatory monocytes to their exit points in the inflamed microvasculature. This platelet‐directed guidance enhances the efficacy of the leukocyte transmigration process and is essential for effective leukocytes responses.Support or Funding InformationSupported by the CRC914 (DFG)

How leukocytes cross the vascular endothelium.

Immune responses depend on the ability of leukocytes to move from the circulation into tissue. This is enabled by mechanisms that guide leukocytes to the right exit sites and allow them to cross the barrier of the blood vessel wall. This process is regulated by a concerted action between endothelial cells and leukocytes, whereby endothelial cells activate leukocytes and direct them to extravasation sites, and leukocytes in turn instruct endothelial cells to open a path for transmigration. This Review focuses on recently described mechanisms that control and open exit routes for leukocytes through the endothelial barrier.

Spatiotemporal expression dynamics of selectins govern the sequential extravasation of neutrophils and monocytes in the acute inflammatory response.

Leukocyte recruitment to the site of inflammation is a key event in a variety of cardiovascular pathologies. Infiltrating neutrophils constitute the first line of defense that precedes a second wave of emigrating monocytes reinforcing the inflammatory reaction. The mechanisms initiating this sequential process remained largely obscure. Using advanced in vivo microscopy and in vitro/ex vivo techniques, we identified individual spatiotemporal expression patterns of selectins and their principal interaction partners on neutrophils, resident/inflammatory monocytes, and endothelial cells. Coordinating the intraluminal trafficking of neutrophils and inflammatory monocytes to common sites of extravasation, selectins assign different sites to these immune cells for their initial interactions with the microvascular endothelium. Whereas constitutively expressed leukocyte L-selectin/CD62L and endothelial P-selectin/CD62P together with CD44 and P-selectin glycoprotein ligand-1/CD162 initiate the emigration of neutrophils, de novo synthesis of endothelial E-selectin/CD62E launches the delayed secondary recruitment of inflammatory monocytes. In this context, P-selectin/CD62P and L-selectin/CD62L together with P-selectin glycoprotein ligand-1/CD162 and CD44 were found to regulate the flux of rolling neutrophils and inflammatory monocytes, whereas E-selectin/CD62E selectively adjusts the rolling velocity of inflammatory monocytes. Moreover, selectins and their interaction partners P-selectin glycoprotein ligand-1/CD162 and CD44 differentially control the intraluminal crawling behavior of neutrophils and inflammatory monocytes collectively enabling the sequential extravasation of these immune cells to inflamed tissue. Our findings provide novel insights into the mechanisms initiating the sequential infiltration of the perivascular tissue by neutrophils and monocytes in the acute inflammatory response and might thereby contribute to the development of targeted therapeutic strategies for prevention and treatment of cardiovascular diseases.

Extra-articular contrast material leaks into locations unrelated to the injection path in shoulder MR arthrography.

To evaluate the localisation, frequency and amount of extravasation in patients with extra-articular contrast material leak into locations unrelated to the injection path in shoulder magnetic resonance (MR) arthrography and associated shoulder disorders. The sites of extravasation were determined on the shoulder MR arthrography of 40 patients. The extravasations were measured on three vertical planes of the MR arthrography. Sufficient joint distension was assessed according to the transverse diameters of the axillary recess on coronal MR images. Extravasation of the contrast material occurred through the subscapular recess, the synovium of the biceps, and the axillary recess. In four cases, extravasations were observed in more than one anatomic location. The most common site of extravasation was along the subscapularis muscle. Superior labrum anterior-posterior (SLAP) lesions were found to be most frequently associated with extravasations. The amount of extravasation was significantly higher in patients with adhesive capsulitis compared with the patients with a different diagnosis (p = 0.022). The extravasations adjacent to the axillary recess do not always indicate glenohumeral ligament pathology. Massive subscapular extravasations were most frequently associated with adhesive capsulitis and SLAP lesions, and might be considered in the MR arthrography report. • Contrast material extravasation may reduce the diagnostic value of shoulder MR arthrography. • The extravasations may occur into locations unrelated to the injection path. • The extravasations adjacent to axillary recess can be misleading for HAGL lesion. • Massive subscapular extravasations were frequently associated with adhesive capsulitis and SLAP lesions.

Quantitative analysis applied to contrast medium extravasation by using the computed-tomography number within the region of interest

The present study was carried out to present a method to analyze extravasation quantitatively by measuring the computed tomography (CT) number after determining the region of interest (ROI) in the CT images obtained from patients suspected of extravasation induced by contrast medium auto-injection. To achieve this, we divided the study subjects into a group of patients who incurred extravasation and a group of patients who underwent routine scans without incurring extravasation. The CT numbers at IV sites were obtained as reference values, and CT numbers at extravasation sites and hepatic portal veins, respectively, were obtained as relative values. Thereupon, the predicted time for extravasation (TEP) and the predicted ratio for extravasation (REP) of an extravasation site were obtained and analyzed quantitatively. In the case of extravasation induced by a dual auto-injector, the values of the CT numbers were confirmed to be lower and the extravasation site to be enlarged when compared to the extravasation induced by a single autoinjector. This is because the physiological saline introduced after the injection of the contrast agent diluted the concentration of the extravasated contrast agent. Additionally, the TEP caused by the auto-injector was about 40 seconds, and we could perform a precise quantitative assessment of the site suspected of extravasation. In conclusion, the dual auto-injection method, despite its advantage of reducing the volume of contrast agent and improving the quality of images for patients with good vascular integrity, was judged to be likely to increase the risk of extravasation and aggravate outcomes for patients with poor vascular integrity by enlarging extravasation sites.

Imaging of immune cell behavior and function in multiple sclerosis and experimental autoimmune encephalomyelitis

AbstractTo visualize the entire process of encephalitogenic T cell infiltration into the target organ, we performed intravital imaging by using two‐photon microscopy in experimental autoimmune encephalomyelitis, the animal model of multiple sclerosis. Intravital imaging documented that T cells first appear in the leptomeningeal blood vessels where they crawl in an integrin‐dependent manner and scan the intraluminal surface for extravasation sites. After diapedesis, the T cells continue to crawl on the abluminal surface, where they meet local antigen presenting cells (APC) that can provide stimuli to the T cells for the subsequent infiltration into the central nervous system (CNS) parenchyma. Although flow cytometric analysis documented that the infiltrated T cells upregulated their activation markers in the CNS meninges, it was unclear at which scanning step the activation occurred. We recently introduced two genetically encoded fluorescent T cell activation sensors for intravital imaging. The first is a fluorescent resonance energy transfer‐based Ca2+ sensor for the quantification of the intracellular Ca2+ concentration, a major step in T cell receptor signaling. The second sensor is a truncated nuclear factor of activated T cells fused to green fluorescent protein, which subcellular localization corresponds to the T cell activation state. Introducing these sensors into the lymphocytes enables the visualization of the interactions of encephalitogenic T cells with different blood–brain barrier structures, and allows us to assess the functional aspect of these interactions directly in vivo. This model system can be further used to evaluate therapeutic compounds and to better understand the activities of T cells in vivo.

Platelets, Tumor Cell Invasiveness, and Metastasis

Platelets have long been known to promote metastasis, and multiple mechanisms have been proposed to explain this phenomenon, including adhesion, coagulation, and protection against natural killer (NK) cells or turbulence. One mechanism that has been little explored is the possibility that platelets might secrete growth factors or provide other stimuli that could enhance the malignant properties of tumor cells. We have shown that pretreatment of carcinoma cells with platelets induces an EMT-like transformation in their properties in vitro and renders them much more metastatic after introduction into mice. TGF-β, produced by platelets and released on their activation is essential for both the in vitro and the in vivo effects. However, TGF-β alone is insufficient; platelet-tumor cell contact is also required and this contact activates NFkB signaling, which synergizes with the TGF-β signaling. Both signals are required for the enhancement of metastasis. In addition to enhancing migration and invasion in vitro, platelets enhance extravasation in vivo. Earlier work has shown that both P-selectin (expressed on platelets) and L-selectin (expressed on leukocytes) are essential for efficient metastasis, and aggregates of tumor cells, platelets, and leukocytes can be observed at sites of tumor cell arrest and extravasation. It has also been demonstrated by others that leukocytes can enhance extravasation and metastatic seeding. Therefore, we have been interested in the question of the relative roles of platelets and leukocytes in these processes. Which cell types are recruited at the sites of metastatic seeding? Does one cell type depend on another? Which cell types enhance metastasis? What roles do the platelets play in recruiting the other cell types? The involvement of platelets in enhancing metastasis also raises questions about the effects of platelets on circulating tumor cells (CTCs). Could platelets enhance the metastatic capacity of CTCs? Could it be the case that only those CTCs that are associated with platelets and/or leukocytes are functionally involved in seeding metastases? Such aggregates are not scored in most current assays for CTCs and will require new investigative approaches. Platelet participation in metastasis also raises the possibility of therapeutic interventions targeting platelet-specific targets and the paracrine interactions between them and other cells. Disclosures:No relevant conflicts of interest to declare.