Retrospective study of the incidence of sarcoidosis-like reaction in patients treated with immunotherapy

AIM

To assess the frequency of radiographically evident drug-induced sarcoidosis-like reaction (DISR) in patients treated with anti-cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) therapy, anti-programmed cell death protein 1 (PD-1) therapy, or a combination of both in a single centre.

MATERIALS AND METHODS

The images and medical records of 457 patients with metastatic melanoma or head and neck cancer treated with either anti-CTLA-4 therapy, anti-PD-1 therapy, or a combination of both at University of California medical centre were reviewed retrospectively and the incidence of radiological manifestations of DISR was assessed among these treatment groups.

RESULTS

Radiological manifestations of DISR were found in 19/457 patients (4.1%). The mean interval from the initiation of immunotherapy to development of DISR was 5.5 months (range 2.3-13.5 months). Mean interval from radiological detection of DISR to imaging evidence of resolution was 5.8 months (range 1.6-18.3 months). Three patients out of 81 (3.7%), 11/297 (3.7%), and 5/79 (6.3%) developed sarcoidosis-like reaction after treatment with anti-CTLA-4 antibody, anti-PD-1 antibody, and a combination of both, respectively. Most patients with DISR were asymptomatic and did not require systemic therapy. Most patients did not demonstrate concomitant increased maximum standardised uptake value (SUVmax) in other organs on their integrated 2-[¹⁸F]-fluoro-2-deoxy-d-glucose (FDG) positron-emission tomography (PET)/computed tomography (CT).

CONCLUSIONS

In the present retrospective study of patients treated with immune checkpoint inhibitors (ICIs), DISR occurred in approximately 3.7% of patients treated with either anti-CTLA-4 or anti-PD-1 antibody and 6.3% of patients treated with a combination of both.

Abstract 3295: The Nanoprimer: A nanoparticle designed to the efficacy of nucleic acid-based therapeutics in oncology

Nucleic acid drugs have shown promise in oncology, however their use is limited by hepatic clearance. Due to the mononuclear phagocytic system (MPS), a large part of the intravenously-administered dose does not reach the therapeutic target. Our approach aims to address this issue using biocompatible nanoparticles—the Nanoprimer—that is administered prior to the therapeutic. Due to its physico-chemical properties, the Nanoprimer is transiently internalized by Kupffer cells (KC), and endothelial cells of the MPS, enabling temporary reduction of hepatic clearance. These data further explore the Nanoprimer’s mechanism of action and demonstrate that scavenger receptor-A (SR) is the main receptor involved in Nanoprimer binding and uptake by KC. Efficacy studies in mouse model show that the Nanoprimer dramatically increases the anti-tumor efficacy of nucleic acid-based treatment without introducing additional toxicities. An in vitro toxicity evaluation was performed investigating the Nanoprimer’s hemolytic properties and its potential ability to activate the complement system, platelet aggregation and pro-inflammatory cytokines*. SR-mediated binding and uptake of Nanoprimer by KC were assessed using a competitive binding assay with SR inhibitor polyinosinic acid. The impact of the Nanoprimer on anti-tumor efficacy was evaluated on orthotopic triple negative breast cancer (TNBC) model in combination with siRNA-loaded lipid nanoparticles (LNPs) targeting a novel cancer-specific gene transcript of a master regulator of invadopodia formation and Wnt, Hedgehog and Notch oncogenic pathways. Results showed that the Nanoprimer is safe at the effective dose. The Nanoprimer does not activate the complement components, induce hemolysis, platelet aggregation, or cytokine storm syndrome elements. The competitive inhibition of SR-A decreases Nanoprimer binding and KC-uptake by 70%, indicating SR-A selective uptake of the Nanoprimer by macrophages. The efficacy study shows that combining the Nanoprimer with siRNA LNP therapy significantly increased treatment efficiency, with a mean tumor growth inhibition ratio of 36.3% for LNPs alone versus 84.6% for the combination. Moreover, the combination therapy more efficiently prevents the development of pulmonary metastatic tumors, with a metastasis-inhibition rate of 98%. These data demonstrate the safety of the Nanoprimer, along with its ability to maximize the inhibition of primary tumor growth and pulmonary metastasis by systemic siRNA LNP therapy in a TNBC mouse model. They also highlight the capacity of Nanoprimer technology to unlock the potential of nucleic acid-based treatments. The ubiquitous nature of its mode of action allows its application to a broad spectrum of anti-cancer therapeutics. *we acknowledge NCL, Frederick National Laboratory for Cancer Research sponsored by the NCI for the help with conducting these experiments

Citation Format: Julie Devallière, Laurence Poul, Maxime Bergère, Audrey Darmon, Océane Jibault, Francis Mpambani, Kelvin Tsai, Matthieu Germain. The Nanoprimer: A nanoparticle designed to the efficacy of nucleic acid-based therapeutics in oncology [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3295.

A2 MUCUS DEFICIENCY IMPACTS INTESTINAL EPITHELIAL CELL PROLIFERATION INDEPENDENT OF THE MICROBIOTA

Background

Intestinal homeostasis is highly dependent on the proliferation and differentiation of intestinal epithelial cells (IEC). IEC arise from intestinal stem cells (ISCs) that reside at the bottom of intestinal crypts. Following proliferation, the IEC migrate up as transient amplifying (TA) cells, and differentiate into mature IEC subtypes. When this process is disrupted, it can lead to aberrant IEC proliferation and differentiation. Mucus production by secretory goblet cells is also crucial for intestinal homeostasis, as mucus separates the IEC from luminal microbiota. Surprisingly, mice lacking Muc2, the main protein component of mucus, display increased distal colonic IEC proliferation and crypt hyperplasia at baseline, suggesting a relationship between Muc2 production and IEC proliferation.

Aims

We investigated how mucus production impacts IEC proliferation and differentiation in the intestinal crypt.

Methods

We used wildtype (Muc2^+/+) and Muc2 deficient (Muc2^-/-) littermates to measure distal colon crypt length and IEC proliferation pattern via microscopy. Organoids were also derived from distal colons of Muc2^+/+ and Muc2^-/- mice, and quantified for size, density and proliferation for 7 days to test whether the hyper-proliferation phenotype was also seen in vitro, thus epithelial-intrinsic. Crypts and organoids were collected for RNA sequencing to examine changes in IEC proliferation pathways. Proliferation assessments were repeated in germ-free (GF) Muc2^+/+ and Muc2^-/- mice. Muc2^-/- mice were also cross-bred with Lgr5^{-EGFP-IRES-CreERT2} mice to investigate the contribution of ISCs to IEC hyperproliferation resulting from Muc2 deficiency.

Results

Significant crypt hyperplasia was observed in the distal colons of Muc2^-/- mice in concert with a > twofold increase in Ki67⁺ TA cells as compared to Muc2^+/+ mice. Similarly, Muc2^-/- organoids also displayed significantly greater size, density and an increased number of Ki67⁺ cells than Muc2^+/+ organoids. Hyperproliferation was also seen in GF mice and organoids, suggesting that mucus impacts IEC proliferation independent of the microbiome. Muc2^-/- Lgr5-EGFP⁺ mice showed no significant increase in numbers of Lgr5⁺ cells, indicating that Muc2 deficiency does not directly impact ISC number, but rather their proliferation and differentiation reflected in increased numbers of TA cells. RNA-sequencing results suggested that changes in lipid metabolism may underlie the increased IEC proliferation seen in Muc2^-/- mice.

Conclusions

Mucus not only promotes IEC homeostasis by separating luminal bacteria from the intestinal epithelium, but also intrinsically modifies IEC proliferation independent of the microbiota. Taken together, our results emphasize the importance of mucus in controlling gut health through mechanisms independent of its role in barrier function.

Funding Agencies

CCC, CIHRC.H.I.L.D Foundation

A7 AN INULIN-TYPE FRUCTAN ENRICHED EXCLUSIVE ENTERAL NUTRITION FORMULA MODULATES THE GUT MICROBIOME AND PROMOTES EXPANSION OF ANTI-INFLAMMATORY T CELL SUBSETS TO SUPPRESS COLITIS

Background

Exclusive enteral nutrition (EEN), a nutritionally complete fiber-free enteral formula, is the gold standard therapy for newly diagnosed children with Crohn’s disease (CD) but this therapy is not routinely used in pediatric ulcerative colitis patients due to lower efficacy in this subgroup. EEN therapy leads to high remission rates, however it also leads to a dysbiotic gut microbiota profile and disease relapse occurs in 60–80% of CD patients within 12 months of EEN discontinuation. Little is known about the mechanisms underlying the actions of EEN. Notably, previous studies have demonstrated that prebiotics, such as inulin-type fructans (IN), can beneficially modulate the gut microbiome, increase butyrate production and reduce inflammation by leading to anti-inflammatory T cell (i.e. FOXP3+IL10+ CD4+) expansion. To date, the effects of an IN enriched EEN (EEN IN) have not been studied.

Aims

To examine the effects of EEN vs EEN IN on colitis development, the gut microbiome and CD4+ T cell subsets using an adoptive T cell transfer model of colitis.

Methods

Mice were split into four groups: 1) Control – normal chow + PBS (n=13; negative control), 2) Chow – normal chow + naive T cell transfer (n=13; positive control), 3) EEN – Ensure Plus® + naive T cell transfer (n=13) and 4) EEN IN – Ensure Plus® with 3% IN + naive T cell transfer (n=13). Naïve T cells (or PBS) were transferred into TCR-b deficient mice and each group was started on their subsequent diets. The naïve T cells will expand into anti- or pro-inflammatory T cells subsets to either cause or suppress colitis in a gut microbiome dependent manner. Body weight and disease activity were monitored for 5-weeks. At the end of the experiment, spleen weights and colon lengths were recorded. Spleen and mesenteric/colonic lymph nodes (MLN) were collected for T cell subset analysis using flow cytometry. Gut microbiota differences were assessed using ddPCR. Short-chain fatty acid levels were analyzed using gas chromatography. The histopathology of the distal colon was scored.

Results

Mice fed EEN IN showed a reduction in colonic shortening (p<0.001) and histology scores (p=0.0088) compared to EEN mice, and reduced disease activity (p=0.0046) compared to Chow mice. Moreover, EEN IN mice showed a higher expansion of FOXP3+IL10+ CD4+ T cells in the MLN (p=0.0424) and spleen (p=0.0088). EEN IN also led to higher butyrate, Bifidobacterium and Bacteroides concentrations compared to EEN (p=0.0113, p=0.0063, p=0.0224; respectively) and Chow (p=0.0252, p=0.0042, p=0.0416; respectively).

Conclusions

EEN IN lead to superior outcomes compared to EEN and Chow. These results provide evidence to support undertaking a clinical trial utilizing EEN IN in pediatric inflammatory bowel disease patients.

Funding Agencies

Michael Smith Foundation for Health Research

CERKL is upregulated in cutaneous squamous cell carcinoma and maintains cellular sphingolipids and resistance to oxidative stress

BACKGROUND

Ceramide kinase-like protein (CERKL) was originally described in retinal tissue. CERKL has been shown to protect cells from oxidative stress, and mutations in CERKL underlie the inherited disease retinitis pigmentosa. CERKL expression maintains cellular sphingolipids via an unknown mechanism.

OBJECTIVES

To determine whether CERKL is expressed in epidermis and cutaneous squamous cell carcinoma (cSCC) and whether CERKL expression affects cSCC sphingolipid metabolism and susceptibility to oxidative stress.

METHODS

CERKL expression was determined by RNA-Seq, quantitative polymerase chain reaction and immunohistochemistry. CERKL was knocked down in cSCC cells using small interfering RNA. Sphingolipid content was analysed by liquid chromatography-mass spectrometry. Oxidative stress was induced by treatment with H₂ O₂ , and apoptosis was measured using flow cytometry to determine annexin V binding.

RESULTS

CERKL mRNA and protein are highly expressed in actinic keratosis and cSCC in comparison with normal epidermis. CERKL is also expressed in metabolically active epithelial cells in normal hair bulbs and sebaceous glands. CERKL knockdown in cultured cSCC cells reduces cellular sphingolipid content and enhances susceptibility to oxidative stress.

CONCLUSIONS

These findings suggest that CERKL may be important in cSCC progression and could lead to novel strategies for prevention and treatment of cSCC.

CERKL is Upregulated in Cutaneous Squamous Cell Carcinoma and Maintains Cellular Sphingolipids and Resistance to Oxidative Stress

BACKGROUND

Ceramide Kinase-Like Protein (CERKL) was originally described in retinal tissue. CERKL has been shown to protect cells from oxidative stress, and mutations in CERKL underlie the inherited disease, retinitis pigmentosa. CERKL expression maintains cellular sphingolipids via an unknown mechanism.

OBJECTIVES

To determine whether CERKL is expressed in epidermis and cutaneous squamous cell carcinoma (cSCC) and whether CERKL expression affects cSCC sphingolipid metabolism and susceptibility to oxidative stress.

METHODS

CERKL expression was determined by RNA-Seq, qPCR and immunohistochemistry. CERKL was knocked down in cSCC cells using siRNA. Sphingolipid content was analyzed by liquid chromatography-mass spectrometry (LC-MS). Oxidative stress was induced by treatment with H2 O2 , and apoptosis was measured using flow cytometry to determine annexin v binding.

RESULTS

CERKL mRNA and protein are highly expressed in actinic keratosis and cSCC in comparison with normal epidermis. CERKL also is expressed in metabolically active epithelial cells in normal hair bulbs and sebaceous glands. CERKL knockdown in cultured cSCC cells reduces cellular sphingolipid content and enhances susceptibility to oxidative stress.

CONCLUSIONS

These findings suggest that CERKL may be important in cSCC progression and could lead to novel strategies for prevention and treatment of cSCC.

Abstract A49: A dual blockade of N-CoR2- and immune checkpoints induces complete remissions in treatment-refractory tumors

Background: The majority of human malignant tumors are resistant or only partially respond to conventional chemotherapy (C/T) or immunotherapy (I/T) such as immune checkpoint inhibitors (ICIs). Irrespective of the treatments, efficient tumor-cell killing requires amplification of inflammatory signaling, which, however, is tightly regulated by various “checkpoint” mechanisms evolved by epithelial cells to prevent excessive tissue damage induced by virus and immune attack. Novel approaches to disable theses conserved and cell-intrinsic inflammation checkpoints may provide breakthrough and “tumor-agnostic” strategies to circumvent the innate treatment resistance to unleash the full potential of C/T and I/T in treatment-refractory and highly lethal malignant tumors, such as triple-negative breast cancer (TNBC), pancreatic ductal adenocarcinoma (PDAC), and glioblastoma multiform (GBM).

Materials and Methods: We designed and conducted integrated genomic and proteomic screening combined with molecular and functional studies to identify conserved anti-inflammatory pathways that mediate innate and cell-intrinsic resistance to C/T and I/T agents. Preclinical studies were used to validate a gene therapy strategy to disable the inflammation-checkpoint identified from this process.

Results: We uncovered that the cytotoxic and immunogenic death induced by C/T and I/T agents is constrained by repression of a toll-like receptor-2 (TLR-2)/TLR-3- and NF-kB-induced interferon regulatory factor-1 (IRF-1) and interferon (IFN)-gamma anti-viral response program in various malignant tumor cells, including breast cancer, PDAC and GBM. Loss- and gain-of-function studies implicated that co-repressor-2 (N-CoR2) co-translocated with NF-kB p50 into cell nuclei in response to therapy, wherein it serves as an epigenetic checkpoint of this inflammation program by mediating a histone deacetylase-dependent chromatin remodeling and repression of a specific panel of proinflammatory and proapoptotic genes. Thus, high N-CoR2 expression predicts treatment refractoriness and poor prognosis in neoadjuvant or adjuvant-treated breast cancer patients. Blockade of the epigenetic checkpoint function of N-CoR2 by a small decoy of N-CoR2 hypersensitized malignant cells to assorted C/T agents, death ligands, and IFN-gamma. Consistently, intratumoral delivery of the N-CoR2 checkpoint blockade dramatically potentiated systemic C/T and ICI therapies, including anti-PD-1 and anti-CTLA-4 antibodies, and completely halted tumor growth or induced remissions in orthotopic and patient-derived xenograft models of TNBC and GBM.

Conclusion: Our findings suggest that malignant tumors can access intrinsically conserved anti-inflammatory mechanisms that enable them to escape from C/T and I/T. As such, strategies that can override this defense program constitute novel antitumor gene therapies that may be applied to overcome resistance in treatment-refractory tumors and improve patient prognosis.

Citation Format: Kelvin Tsai, Valerie M. Weaver. A dual blockade of N-CoR2- and immune checkpoints induces complete remissions in treatment-refractory tumors [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr A49.

A18 BUILDING BETTER ENTEROIDS: A NOVEL STRATEGY FOR ENRICHING SECRETORY EPITHELIAL CELL SUBTYPES

Background

Inflammatory bowel diseases (IBD) are chronic gastrointestinal disorders that affect more than 270,000 Canadians, including over 7,000 children. Inflammation arising from IBD severely damages intestinal epithelial cells (IECs), however their role in disease pathogenesis is not fully understood, in part due to a lack of in vitro systems that recapitulate the epithelium’s complex cellular composition.

Enteroids are an in vitro model where primary IECs are isolated and cultured as 3D ‘mini guts.’ They offer distinct advantages over cell lines, however current protocols generate enteroids primarily composed of enterocytes that seldom contain rarer IEC subtypes (goblet, enteroendocrine, tuft and Paneth cells). These cells are responsible for the gut’s mucus, antimicrobial and hormone secretory functions, yet their role in the pathophysiology of IBD is unclear.

Aims

Manipulate cell differentiation pathways in mouse and human enteroids to increase the prevalence of secretory IECs, as well as determine if enteroids derived from pediatric IBD patients exhibit impaired responses to differentiation treatments.

Methods

Mouse enteroids were derived from ileal, cecal and colonic crypts of C57BL/6 mice while human enteroids were isolated from healthy or pediatric IBD patient intestinal biopsies. Enteroids were initially supplemented with Wnt signaling activators and the extracellular matrix modified to enhance enteroid culture “stemness”. Differentiation was induced by growth media modulation of the Notch and Wnt signaling pathways. Enteroids were analyzed via flow cytometry to quantify expression of secretory cell markers, while immunofluorescent and Peroidic acid Schiff/Alcian Blue staining was used to visualize goblet cells.

Results

“Stem” treatment potentiated Wnt signaling and enhanced enteroid “stemness” as measured by Lgr5 and CD44 expression. Comparatively, differentiation of these “stem” enteroids led to a larger relative increase in secretory markers. Differentiation treatment increased expression of goblet cell markers (Muc2 and lectin) in the “stem” treated mouse cecal and colonic enteroids, but not in ileal enteroids. Notch inhibition produced increased expression of lysozyme, a Paneth cell marker, in all enteroids.

A similar increase in secretory cell numbers was observed in control human enteroids following differentiation treatment. In contrast, enteroids derived from pediatric IBD patients displayed irregular differentation responses to treatment.

Conclusions

We demonstrate that manipulation of cell differentiation pathways increases the number of secretory IEC subtypes within enteroids. Furthermore, these pro-secretory cell responses differ in IBD patient enteroids, indicating that an alteration of the targeted cell signaling pathways may be linked to IBD pathogenesis.

Funding Agencies

CCC, CIHRBCCHRI Summer Studentship

A44 NOVEL AND HIGHLY SENSITIVE FLOW CYTOMETRIC BASED METHOD FOR CONTINUOUS TRACKING OF INTESTINAL PERMEABILTIY

Background

Inflammatory bowel diseases (IBD) are chronic, inflammatory conditions of the intestinal tract. In addition to a complex mixture of genetic, and environmental factors, increased intestinal permeability is also thought to be involved. Despite its diagnostic importance, there is no reliable yet minimally invasive way to measure intestinal permeability in patients and animal models. Currently, most assays involve the detection of orally given sugar molecules in either the urine (MLR method) or the plasma (FITC-dextran). These methods offer only limited accuracy, and do not allow continual tracking of intestinal permeability within the same animal due to the requirement of euthanization. Herein, we describe a novel cytometric-based method using an ingested dietary protein (ovalbumin (OVA)) and flow cytometry. We show our method is reliable, highly sensitive, minimally invasive and allows for the continuous tracking of intestinal permeability within the same individual using small blood volumes.

Aims

To compare the utility of our bead-based method of intestinal permeability measurement to the FITC-Dextran method.

Methods

Wildtype (WT) C57BL/6 mice, and mucin 2-deficient (Muc2-/-) mice (known to suffer a leaky gut) at baseline, or mice given chemical or infection-induced colitis were gavaged with a solution containing OVA protein and FITC-Dextran. After 6 hours, mice were euthanized to collect plasma for spectrophotometry (FITC-Dextran), or for flow cytometry (bead-based ELISA) analyses.

Results

We found that both OVA and FITC-dextran were detectable in plasma samples of the Muc2-/- mice, but not the WT mice, 6 hours after oral co-administration, however the bead-based method produced more consistent readings. Immunostaining of tissue sections with the same antibodies also showed that OVA can readily diffuse through the gut epithelium of Muc2-/- mice but not the WT mice, validating the specificity of the antibodies. We also tested our assay on WT mice undergoing dextran sodium sulfate (DSS) colitis, or infected with Citrobacter rodentium. We found that our method could detect statically significant changes in intestinal permeability 2 to 3 days earlier than the FITC-dextran method, while providing greatly reduced variability between technical repeats. More importantly, we were able to use a small volume (5 μL) of whole blood collected via tail poke, to measure intestinal permeability without requiring euthanization of the mice. This allowed the continuous tracking of permeability changes within the same animal.

Conclusions

We conclude that the bead-based method is more sensitive and reliable than the FITC-Dextran method as tested in several murine colitis models. More importantly, we showed that the bead-based method allows continual tracking of intestinal permeability within the same animal, enabling time course measurements.

Funding Agencies

CAG, CCC, CIHR, NRCBC Children’s Research Institute

Association between proton pump inhibitors and the risk of hepatocellular carcinoma

BACKGROUND

Proton pump inhibitor (PPI) use has been reported to be associated with liver damage and might possibly be carcinogenic.

AIMS

We examined whether long-term PPI use increases the risk of hepatocellular carcinoma (HCC) in patients without viral hepatitis B or C.

METHODS

We conducted a nested case-control study in a cohort of patients without viral hepatitis in Taiwan from 2000 to 2013. In total, 29 473 HCC cases and 294 508 matched controls were included. Moreover, we identified prescriptions for PPI and durations between the PPI index date and cancer diagnosis date (or the corresponding date in controls).

RESULTS

The adjusted odds ratio (AOR) for HCC associated with PPI use was 2.86 (95% confidence interval [CI], 2.69-3.04). Considering the use of PPIs determined according to cumulative defined daily dose (cDDD) subgroups, a dose-response effect was observed in patients exposed to 29-180, 181-240, 241-300, and 300+ cDDDs of PPIs. The AORs were 2.74 (95% CI, 2.57-2.93), 2.98 (95% CI, 2.50-3.56), 3.23 (95% CI, 2.59-4.02), and 3.43 (95% CI, 2.94-4.00) in the 29-180, 181-240, 241-300, and 300+ cDDD groups, respectively, compared with the 0-28 cDDD group. A sensitivity analysis revealed a consistent association between PPI use and the risk of HCC in subpopulations stratified by risk factors associated with HCC.

CONCLUSIONS

This observational study demonstrated that PPIs might increase the risk of HCC.

Abstract P3-07-08: Recent trends in the characteristics of patients with distant stage breast cancer in the United States Surveillance, Epidemiology and End Stage Disease (SEER) program

Objectives. Even though advances in screening and contemporary diagnostic techniques have led to earlier detection, a proportion of breast cancer patients are still diagnosed with distant stage disease. The objective of this research was to describe the changing demographic and clinical characteristics of patients with distant stage breast cancer.

Methods. We identified women aged 20 years or older who were diagnosed with distant stage primary breast cancer between 1995 and 2009 with non-missing hormone receptor (HR) status in the SEER 18 Registry (1973–2009) database. As staging systems changed across the years of the study, we opted to use the SEER historic stage in our analyses. Trends in demographic and clinical characteristics were evaluated by time period of diagnosis (1995–1999, 2000–2004, 2005–2009) and HR status (HR+ includes ER+/PR+, ER+/PR- and ER−/PR+; HR− includes ER−/PR− only). Statistically significant changes were examined using the Cochran Armitage test.

Results. A total of 30,161 women with distant stage breast cancer were identified. Over the 15 years, the incidence rate (IR) of distant stage disease was stable (10.6 to 10.9 per 100,000 pys), as well as the proportion of HR+ cases (68%).

Age did not vary significantly over time; 55% of the HR+ cases and 45% of the HR- cases were 60 years or older. The proportion of Black and Hispanic patients increased significantly over time (18 to 24% for HR+; 24 to 33% for HR−) -as did the proportion of patients diagnosed with grades I and II cancers (44 to 54% for HR+; and 16 to 20% for HR−). The proportion of ductal histologic diagnoses was stable over time, at 77% among HR+ cases and 93% among HR- cases in 2005–2009. Cancer-directed surgeries (from 63 to 47% for HR+; 72 to 56% for HR−) and radiation therapies (43 to 37% for HR+; 42 to 38% for HR−) became less common over the time. Information on chemotherapy/systemic therapies is unavailable in this dataset.

Conclusions. Although, incidence rate of distant stage breast cancer was stable over a time, there was a higher proportion of diagnosis of grade I/II stage cancer cases potentially due to earlier cancer detections by screening programs. The growing proportion of minorities suggested that screening programs be adjusted to the changing demographics in the United States.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P3-07-08.

Effects of intravenous iron saccharate on improving severe anemia in rheumatoid arthritis patients

Anemia in rheumatoid arthritis (RA) is multifactorial. Iron deficiency, either definite or relative (defect in iron utilization), exists in RA patients with anemia. Intravenous iron therapy is indicated in severe and symptomatic cases or those with conditions precluding use of oral iron, but its safety and long-term efficacy have not been well-established. Forty severe anemic (hemoglobin < 9 g/dL) RA patients with or without demonstrable bone marrow iron stain were enrolled in this study. Fractionated administration of intravenous iron saccharate was undertaken and the median follow-up time was 1 year. All patients exhibited significant elevations of hemoglobin 3 months after treatment, which were more pronounced in the nonstainable iron marrow subjects {median (interquartile range): 3.8 (2.9-4.8) g/dL versus 2.9 (2.0-3.0) g/dL, p < 0.01}. Thereafter, hemoglobin remained at a plateau level that lasted during the observation period. Throughout the whole course, none of the cases exhibited side effects or flare up of disease activities. The use of intravenous iron saccharate, preferably administrated in a fractionated way, is effective in the correction of severe anemia in RA patients, especially those with nonstainable iron marrow.

Analysis of allele fidelity, polymorphic information content, and density of microsatellites in a genome-wide screening for hip dysplasia in a crossbreed pedigree

Recent advances in genomics resources and tools are facilitating quantitative trait locus mapping. We developed a crossbreed pedigree for mapping quantitative trait loci for hip dysplasia in dogs by crossing dysplastic Labrador Retrievers and normal Greyhounds. We show that one advantage to using a crossbreed pedigree is the increased marker informativeness in the backcross/F2 population relative to the founder populations. We also discuss three factors that affect the detection power in the context of this crossbreed pedigree: being able to detect and correct genotyping errors, increasing marker density for chromosomes with a sparse coverage, and adding individuals to the mapping population as soon as they become available.

Multiple intracranial calcifications and spinal compressions: rare complications of type la pseudohypoparathyroidism

Type la pseudohypoparathyroidism (PHP la) is an unusual inherited disease. PHP la often causes extraskeletal calcifications and even soft tissue ossifications. Patients may present neurologic symptoms and signs related to hypocalcemia and hyperphosphatemia. We report here a 38-yr-old woman with PHP la who had two uncommon neurologic complications. One was involuntary movements related to basal ganglia calcification, and the other was myelopathy owing to ossifications of the posterior longitudinal ligament and multiple herniated intervertebral disks. Aggressive body weight control and corrections of hypocalcemia, hyperphosphatemia, and elevated PTH may be important to prevent these unusual neurologic complications. Regular and careful neurologic examinations should be performed for early diagnosis and treatments of these spinal lesions.

Effect of baicalein on apoptosis of the human Hep G2 cell line was induced by mitochondrial dysfunction

The effects of baicalein on the human hepatoblastoma G2 (Hep G2) cell line were investigated in this study. By an SRB viability assay, we demonstrated that baicalein reduced the viability in a dose- and time-dependent manner. The apoptotic features such as chromatin condensation and DNA fragmentation were observed in the baicalein-treated cells. During the process of apoptosis, we noticed a sequential dissipation of mitochondrial membrane potential (DeltaPsim) and an apparent redistribution of cytochrome c from the mitochondria to the cytosol in baicalein-treated cells. Furthermore, the mitochondrial Bcl-2 protein represented a dramatic change in response to baicalein treatment. Altogether, our data suggested that the effect of baicalein on apoptosis of the human Hep G2 cell line was induced by mitochondrial dysfunction and Bcl-2 regulation.

Leukocyte mitochondria alterations after aerobic exercise in trained human subjects

Exercise is associated with intensity-dependent immune disturbances. Leukocyte mitochondrial alterations and apoptosis may contribute to this phenomenon.

PURPOSE

To investigate the effects of different intensities of aerobic exercise (AE) on leukocyte mitochondrial transmembrane potential (MTP) and the propensity of apoptosis.

METHODS

Blood samples were collected from 12 subjects who performed AE for 3 consecutive days (35% maximal oxygen consumption (VO2max)). Leukocyte MTP and apoptosis were measured by flow cytometry. The subjects performed two additional sessions of AE of higher intensities (60% and 85% VO2max) with an intervening 4-wk washout period. The measurements were repeated during each session.

RESULTS

Leukocyte MTP declined during daily, repetitive AE at an intensity of 60% and 85% VO2max. Similar changes were not found during a more moderate AE (35% VO2max). Leukocytes increased their propensity of apoptosis a period (3-5 d) after the start of the AE.

CONCLUSION

High-intensity AE has accumulative effects on the mitochondrial energization status and vitality of peripheral blood leukocytes. Leukocyte MTP is a potentially applicable indicator for monitoring immune distress due to overtraining.

Oxidative DNA damage in human peripheral leukocytes induced by massive aerobic exercise

Reactive oxygen species produced during vigorous exercise may permeate into cell nuclei and induce oxidative DNA damage, but the supporting evidence is still lacking. By using a 42 km marathon race as a model of massive aerobic exercise, we demonstrated a significant degree of unrepaired DNA base oxidation in peripheral immunocompetent cells, despite a concurrent increase in the urinary excretion of 8-hydroxy-2'-deoxyguanosine. Single cell gel electrophoresis with the incorporation of lesion-specific endonucleases further revealed that oxidized pyrimidines (endonuclease III-sensitive sites) contributed to most of the postexercise nucleotide oxidation. The oxidative DNA damage correlated significantly with plasma levels of creatinine kinase and lipid peroxidation metabolites, and lasted for more than 1 week following the race. This phenomenon may be one of the mechanisms behind the immune dysfunctions after exhaustive exercise.

Leukocyte mitochondria depolarization and apoptosis in advanced heart failure: clinical correlations and effect of therapy

OBJECTIVES

The purpose of this study was to examine the changes in leukocyte mitochondrial transmembrane potential (MTP) and its association with apoptosis in congestive heart failure (CHF).

BACKGROUND

Congestive heart failure is a heterogeneous syndrome with multiple hemodynamic, neuroendocrine and immune abnormalities. Although edematous CHF may be associated with endotoxemia and increased cytokine production, peripheral blood leukocyte functions in advanced CHF remain unclear.

METHODS

Thirty patients with acute decompensated CHF (mean age [+/- SEM] 74.9 +/- 3.1 years) and 20 healthy controls underwent determination of MTP, intracellular oxidants and apoptosis in three subsets of peripheral blood leukocytes. The measurements were repeated after the time of recompensation.

RESULTS

Patients with acute CHF showed marked MTP reduction and increased intracellular oxidant formation in three subsets of leukocytes upon entry into the study. These changes were more prominent in patients with peripheral edema. The decline in MTP was correlated with the severity of the peripheral edema and plasma concentration of cortisol, nitrogen metabolites and tumor necrosis factor-alpha (p < 0.01). After clinical stabilization, MTP gradually recovered. Leukocytes underwent increased propensity of apoptosis one week after the time of recompensation.

CONCLUSIONS

The mitochondrial depolarization and apoptosis of leukocytes in decompensated heart failure suggest that CHF is associated with severity-dependent impairments in leukocyte function. Accentuated hormonal and cytokine abnormalities and increased circulating oxidants may contribute to these changes. Early and aggressive management of advanced heart failure is helpful in the recovery of these immune abnormalities.

Age-related changes in the mitochondrial depolarization induced by oxidative injury in human peripheral blood leukocytes

Aging is associated with impaired immunity and reduced host defenses. Mitochondrial bioenergetic dysfunctions and reduced antioxidative ability of immunocompetent cells may contribute to this phenomenon. In this study, 60 healthy volunteers of different age groups donated their blood after overnight fasting. Leukocytes were subjected to oxidative injuries by exposure to t-butylhydroperoxide, and were labeled with fluorochromes for measuring mitochondria transmembrane potential (delta psi m), membrane peroxidation and mitochondrial oxidant formation. delta psi m declined after t-butylhydroperoxide exposure, and the change was more prominent in leukocytes from older individuals. Cyclosporin A partly restored delta psi m, implying the contributing role of mitochondrial permeability transition pores. The mitochondrial depolarization was accompanied by increased oxidant formation and oxidation of pyridine nucleotides, which were more prominent in older subjects. The results support the view that the bioenergetic functions of mitochondria are more susceptible to oxidative injury in aged individuals. The decreased ability of leukocytes to resist oxidative stress may contribute to immunosenescence in humans.

Investigation of an outbreak caused by methicillin-resistant Staphylococcus aureus in a cardiovascular surgery unit by ribotyping, randomly amplifed polymorphic DNA and pulsed-field gel electrophoresis

An outbreak caused by rapid spread of methicillin-resistant Staphylococcus aureus (MRSA) in an intensive care unit for cardiovascular surgery was investigated by phenotypic and genotypic methods. Fourteen isolates were collected during a 2-month period from clinical and environmental specimens in the unit recently re-opened after reconstruction. The isolates were tested for antibiotic susceptibility patterns and genotyped by automated ribotyping, randomly amplified polymorphic DNA-PCR (RAPD) analysis and pulsed-field gel electrophoresis (PFGE). Automated ribotyping applying EcoRI digestion proved to be of no value in separating the isolates. In contrast, PFGE grouped the isolates into four clusters different from the reference strain. These results fully correlated with the antibiograms. Twelve of the isolates were grouped into two clonally related clusters. RAPD analyses grouped the isolates into five clusters. Except for two isolates of one patient, which had different RAPD patterns, PFGE and RAPD analyses presented very similar results. The results verified the usefulness of PFGE in studies of MRSA epidemics. A combination of these two methods reduces the time to identification of an outbreak and increases the accuracy in detection of intraspecies differences.

A simple intraductal aspiration method for cytodiagnosis in nipple discharge

OBJECTIVE

To increase cytodiagnostic accuracy for women with spontaneous nipple discharge using a simple intraductal aspiration method.

STUDY DESIGN

We compared the cytodiagnostic accuracy of the conventional squeezing collection method and intraductal aspiration by intravenous catheter in a total of 146 women with spontaneous nipple discharge in a single duct without a mass; they had been pathologically identified at Kaohsiung Medical University Hospital.

RESULTS

Adequate specimens were collected in 96.6% (141/146 cases) of the sample by the intraductal aspiration method as compared to 76.0% collected by the conventional squeezing method (P < .05). An adequate specimen should consist, at a minimum, of six cohesive clusters of well-preserved epithelial cells, with each cluster composed of at least five cells other than foam cells. The cytologic diagnosis was divided into five categories: positive in 9 cases, suspicious in 10, negative with atypical findings in 59, negative in 33 and inadequate specimens in 35 cases that employed the squeezing method. These results were less satisfactory than with the intraductal aspiration method: the smears were positive in 17 cases, suspicious in 14, negative with atypical findings in 78, negative in 32 and inadequate specimens in 5. Our results showed a sensitivity of 92.3% and specificity of 93.9% for the intraductal aspiration method as compared to a sensitivity of 52.9% and specificity of 89.3% for the squeezing method. Among the 27 cancers in this series, correct cytodiagnosis, including suspicious cases, was made in 24 cases by intraductal aspiration, with an accuracy of 88.9%, as compared to the 33.3% (9/27) accuracy of the squeezing method (P < 0.5).

CONCLUSION

For patients with spontaneous nipple discharge, the intraductal aspiration method provides much more accurate cytodiagnosis than does the conventional squeezing method.

Detrusor myopathy in young beagle dogs

Hematoxylin and eosin-stained sections of urinary bladder were examined microscopically from 449 male and female beagle dogs after 2- to 4-week toxicology studies. Degenerative lesions (detrusor myopathy) of the urinary bladder muscular tunic were present in 59 of 449 (13%) dogs. Myopathic lesions consisted of focal to multifocal areas of smooth muscle fiber atrophy with cytoplasmic basophilia and vacuolation, individual cell necrosis, enlarged smooth muscle nuclei and nucleoli, and occasional mitotic figures. Adjacent areas of arteritis and periarteritis were present in 10 of 59 (17%) beagles with detrusor myopathy suggesting a possible ischemic pathogenesis of the smooth muscle lesions. There was no significant difference in prevalence of myopathy in beagles administered vehicle or various test compounds. Prior urinary catheterization procedures appeared to augment the prevalence of myopathy; some lesions were adjacent to minor, iatrogenically traumatized urinary bladder mucosa. Muscle lesions were not observed in urinary bladders from mongrel dogs, monkeys, cats, rats, or microswine. When compared to crossbred dogs and other laboratory species, the beagle dog thus appears to be sensitive to development of detrusor myopathy.

Is the endogenous peroxyl-radical scavenging capacity of plasma protective in systemic inflammatory disorders in humans?

Systemic inflammatory response syndrome (SIRS) in humans is associated with heightened intravascular oxidative stress. The clinical significance of plasma endogenous antioxidative capability in SIRS remains undetermined. Time-sequence changes of plasma total radical-trapping antioxidant parameter (TRAP) and its components were measured in 135 patients with various clinical conditions leading to SIRS. The results were correlated with clinical parameters. Plasma TRAP significantly depressed upon diagnosis of SIRS (SIRS vs. healthy subjects (n = 50), 605.7 +/- 20.4 vs. 803.4 +/- 30.8 microM Trolox equivalent, p <.001). In survivors (n = 86), TRAP declined further during the course of SIRS, followed by a mild recovery at the end of follow-up. General linear mixed model analysis revealed that uric acid, vitamin C, vitamin E and unidentified antioxidants contributed to most of the changes in TRAP (each factor p <.001). In nonsurvivors (n = 49), TRAP increased steadily until death, and the increase was predominantly the result of the increased contribution of bilirubin (p <.01). Higher TRAP levels were not correlated with diminished blood oxidants formation (r = -0.13, p.05), lower intensity of lipid peroxidation (r = 0.261, p <.05) or lesser disease severity of SIRS. The results do not support the hypothesis that the endogenous peroxyl radical scavenging ability of plasma plays a protective role in the course of SIRS.

Magnolol attenuates peroxidative damage and improves survival of rats with sepsis

Reactive oxygen species and peroxidative damage are implicated in the pathophysiology of sepsis. Magnolol is a compound extracted from the Chinese medicinal herb Magnolia officinalis and has multiple pharmacological effects, notably antioxidant functions. To determine whether magnolol can modulate the course of sepsis, survival rate and biochemical parameters were analyzed in rats with sepsis with various treatment protocols. Magnolol at doses ranging from 10(-9) g/kg to 10(-5) g/kg was administered either before or after induction of sepsis by cecal ligation and puncture. Magnolol did not modulate the course of sepsis induced by two cecal punctures. When one cecal puncture was performed, a moderately evolving type of sepsis was induced, and the survival rate of affected rats was significantly improved by pretreatment with 10(-7) g/kg magnolol. The beneficial effect was partially retained if magnolol was administered 6 hours after onset of sepsis when a higher dose (10(-5) g/kg) was used. The intensity of lipid peroxidation in plasma, liver, and lung of septic rats was also attenuated in a treatment-dependent manner. Magnolol at this dose range exerted these beneficial effects probably through its antioxidant efficacy. These significant results may suggest magnolol as a candidate agent for the treatment of sepsis.

Differential effects of bone mineral content and bone area on vertebral strength in a swine model

Since the biomechanical competence of a vertebral body may be closely related to the content and distribution of the bone mineral, we have evaluated the effects of projected vertebral bone area (BA) and bone mineral parameters [bone mineral content (BMC) or bone mineral density (BMD)] on their biomechanical competence. We used dual-energy X-ray absorptiometry (DXA) to assess the bone mineral parameters of 36 swine thoracic vertebrae (T1-T12) and 15 lumbar vertebrae (L1-L5) after removal of the posterior elements. The failure load, compressive stress, and the stored strain energy of these vertebral bodies were assessed by a uniaxial compressive test using an MTS 810 testing system. Multiple regression analysis showed a significantly negative effect of BA and significantly positive effect of BMC on the biomechanical competence (compressive stress, r2 = 0.67, P < 0.0001; failure load, r2 = 0.75, P < 0.0001). However, the stored strain energy was only related to the BMC (r2 = 0.35, P < 0.0001). The contributory effects of BMC and BA on the biomechanical competence were not equal. The effects of BMC was larger than BA in determining the failure load and stored strain energy, whereas the reverse was found for the compressive stress. Using the log-transformed parameters as the regressors resulted in similar results. These results suggested the differential effects of BA and BMC in determining the biomechanical competence of vertebral bodies. We recommend the use of both parameters instead of BMD alone for evaluation of the vertebral biomechanical competence.

Oxidative stress: an important phenomenon with pathogenetic significance in the progression of acute pancreatitis

BACKGROUND

Reactive oxygen species and related oxidative damage have been implicated in the initiation of acute pancreatitis. Changes in these parameters during disease progression merit further investigation.

AIMS

To evaluate changes and the clinical relevance of superoxide radicals, endogenous antioxidants, and lipid peroxidation during the course of acute pancreatitis.

PATIENTS AND METHODS

Superoxide radicals (measured as lucigenin amplified chemiluminescence), ascorbic acid, dehydroascorbic acid, alpha tocopherol, and lipid peroxidation (measured as thiobarbiturate reactive substances) were analysed in blood samples from 56 healthy subjects, 30 patients with mild acute pancreatitis, and 23 patients with severe acute pancreatitis. The association with grades of disease severity was analysed. Measurements were repeated one and two weeks after onset of pancreatitis.

RESULTS

In the blood from patients with acute pancreatitis, there were increased levels of the superoxide radical as well as lipid peroxides. There was notable depletion of ascorbic acid and an increased fraction of dehydroascorbic acid. Changes in alpha tocopherol were not great except in one case with poor prognosis. Differences between severe and mild acute pancreatitis were significant (p < 0.01). Variable but significant correlations with disease severity scores were found for most of these markers. The normalisation of these indexes postdated clinical recovery one or two weeks after onset of disease.

CONCLUSIONS

Heightened oxidative stress appears early in the course of acute pancreatitis and lasts longer than the clinical manifestations. The dependence of disease severity on the imbalance between oxidants and natural defences suggests that oxidative stress may have a pivotal role in the progression of pancreatitis and may provide a target for treatment.

Symmetry of bone mineral density at the proximal femur with emphasis on the effect of side dominance

The symmetry and effect of side dominance on the bone mineral density (BMD) of proximal femur was evaluated in 266 normal Chinese women with a dual photon absorptiometer (DPA, Norland 2600). The BMDs of the femoral neck, trochanter, and Ward's triangle at the proximal femur in the dominant leg (BMDd) were compared with those of the nondominant side (BMDn). The linear regression of BMDd and BMDn of the corresponding regions at the proximal femur showed a good correlation (r = 0.893-0.941, SEE = 0.052-0.062 g/cm2). The paired difference of proximal femoral BMD was -0.002 +/- 0.062 g/cm2 for the femoral neck, 0.003 +/- 0.054 g/cm2 for the trochanter, and 0.008 +/- 0.062 g/cm2 for the Ward's triangle. The ratio of asymmetry for femoral neck BMD was mean +/- SD = -0.4 +/- 7.8%, for trochanter 0.6 +/- 8.1%, and for the Ward's triangle 1.3 +/- 9.7%. Both paired difference and ratio of asymmetry between BMDd and BMDn were approximately normally distributed, with a mean +/- 2 SD ranging from -0.126 to 0.122 g/cm2 for paired difference and -16.0% to 15.2% for the ratio of asymmetry in the femoral neck. These data revealed that dominance had little effect on the proximal femur BMDs. However, the wide range of paired difference and ratio of asymmetry of the proximal femur BMD in the normal individuals should be considered in the interpretation of the proximal femoral BMD.

Prevalence of vertebral fractures in chinese men and women in urban Taiwanese communities

Reports on the prevalence (or incidence) rates of vertebral fracture have been available, but they are limited concerning non-white populations and men of all races. This study used the radiomorphometric method to survey the prevalence rate of vertebral fracture for ethnic Chinese women 40 years and older and Chinese men 65 and older who were randomly selected from four major cities in Taiwan. Three sets of reference values of the height ratios were used for middle-aged women, elderly women, and elderly men. The results showed that in Chinese women, the prevalence rate of vertebral fracture was low before age 50 and showed a steady increase thereafter. In men, the increase was small until age 80. The overall adjusted prevalence rate of vertebral fracture for women older than 65 was 20% and that for men, 12.5% (95% confidence interval 18-22% and 11-14%, respectively.) If only severe deformity was counted [height ratio lower than normal mean minus 4 standard deviations (SD), or Grade II deformity], the adjusted prevalence rate was 15.5% for elderly women and 9.5% for elderly men (95% confidence interval 14-17%, and 8-11%, respectively.) The overall adjusted prevalence rate for women aged 40 and over was 6.8% (95% confidence interval 5.7-8%), or 4.5% (95% confidence interval 3.6-5. 5%) for Grade II lesions. Moreover, for subjects with fracture, elderly women tended to have more fractured vertebrae per person and more Grade II fractures than elderly men. Thus, Chinese women residing in cities of Taiwan had a relatively high prevalence rate of vertebral fracture, a finding compatible with that for United States or European white women, or for Japanese women residing in America. Elderly Chinese men also have a high prevalence rate of vertebral fracture. The age-specific female-to-male ratio of prevalence rate was about 1.5 to 2.3 between age 65 and 80, and close to unity after age 80.

Dimensional complexity of EEG waveforms in neuroleptic-free schizophrenic patients and normal control subjects

Dimensional complexity reflects the number of independent variables contributing to a dynamic process. EEG epochs recorded from 12 neuroleptic-free schizophrenic patients and 11 normal control subjects were Laplacian-filtered to highlight activity specific to prefrontal and parietal areas, and dimensional complexity measures of the resulting signals were then derived. Complexity of EEG waveforms generated by schizophrenic patients was depressed relative to that of normal subjects, especially in left frontal and right parietal regions. These data suggest that complexity of underlying is also reduced.

Stability of interleukin 1 beta (IL-1 beta) in aqueous solution: analytical methods, kinetics, products, and solution formulation implications

The thermal stability of IL-1 beta in aqueous solution as a function of temperature (5-60 degrees C), pH (2-9), buffer (acetate, citrate, tris, and phosphate), and cyroprotectants (sugars, HSA) was investigated in this study. The analytical methodologies included RP-HPLC, SEC, ELISA, IEF-PAGE, SDS-PAGE, and bioassay. The degradation and inactivation of IL-1 beta at or above 39 degrees C were attributed to autoxidation of the two cysteine residues in the denatured protein, followed by hydrophobic/covalent aggregation and precipitation. At or below 30 degrees C, IEF- and SDS-PAGE results suggest a possible deamidation reaction. The difference in mechanism of degradation precludes the prediction of formulation shelf life from accelerated temperature data. Nonetheless, the good stability observed at 5 degrees C suggests that a solution formulation may be feasible for IL-1 beta.

The pathogenesis of epizootic hemorrhagic disease of deer: an electron microscopic study

Ultrastructural studies on capillaries and arterioles from tongue and heart tissues of 3 deer and from a portion of the cerebral hemisphere of a deer experimentally infected with epizootic hemorrhagic disease (EHD) virus revealed striking changes in the vascular endothelial cells. These changes included the focal development of moderately electron-dense materials (viral matrices), aggregations of virus particles and tubules in the cytoplasm. In addition, enlargement of endothelial cells and degenerative changes in some of the endothelial cells were frequently observed. The lumens of affected capillaries and arterioles were often noted to be occluded by fluffy, moderately electron-dense substances or by aggregates of highly electron-dense fibrin which appeared to be adherent to the surface of endothelial plasma membrane. Platelets were frequently present in the capillaries, intermingled with fibrin materials, and appeared either intact or partially or completely degranulated. These observations suggest that viral injury to endothelial cells resulting from EHD virus replication may initiate intravascular thrombosis, and that the hemorrhagic lesion is a manifestation of virus-cell interaction.