Coronary CT-based FFR in patients with acute myocardial infarction might predict follow-up invasive FFR: The XPECT-MI study.

BACKGROUND: We aimed to evaluate whether invasive fractional flow reserve (FFRi) of non-infarction related (non-IRA) lesions changes over time in ST-elevation myocardial infarction (STEMI) patients. Moreover, we assessed the diagnostic performance of coronary CT angiography-derived FFR(FFRCT) following the index event in predicting follow-up FFRi. METHODS: We prospectively enrolled 38 STEMI patients (mean age 61.6 â€‹± â€‹9 years, 23.1% female) who underwent non-IRA baseline and follow-up FFRi measurements and a baseline FFRCT (within ≤10 days after STEMI). Follow-up FFRi was performed at 45-60 days (FFRi and FFRCT value of ≤0.8 was considered positive). RESULTS: FFRi values showed significant difference between baseline and follow-up (median and interquartile range (IQR) 0.85 [0.78-0.92] vs. 0.81 [0.73-0.90] p â€‹= â€‹0.04, respectively). Median FFRCT was 0.81 [0.68-0.93]. In total, 20 lesions were positive on FFRCT. A stronger correlation and smaller bias were found between FFRCT and follow-up FFRi (ρ â€‹= â€‹0.86,p â€‹< â€‹0.001,bias:0.01) as compared with baseline FFRi (ρ â€‹= â€‹0.68, p â€‹< â€‹0.001,bias:0.04). Comparing follow-up FFRi and FFRCT, no false negatives but two false positive cases were found. The overall accuracy was 94.7%, with sensitivity and specificity of 100.0% and 90.0% for identifying lesions ≤0.8 on FFRi. Accuracy, sensitivity, and specificity were 81.5%, 93.3%, and 73.9%, respectively, for identifying significant lesions on baseline FFRi using index FFRCT. CONCLUSION: FFRCT in STEMI patients close to the index event could identify hemodynamically relevant non-IRA lesions with higher accuracy than FFRi measured at the index PCI, using follow-up FFRi as the reference standard. Early FFRCT in STEMI patients might represent a new application for cardiac CT to improve the identification of patients who benefit most from staged non-IRA revascularization.

Clinical Validation of a Virtual Planner for Coronary Interventions Based on Coronary CT Angiography.

BACKGROUND: Low fractional flow reserve (FFR) values after percutaneous coronary intervention (PCI) carry a worse prognosis than high post-PCI FFR values. Therefore, the ability to predict post-PCI FFR might play an important role in procedural planning. Post-PCI FFR values can now be computed from pre-PCI coronary computed tomography angiography (CTA) using the fractional flow reserve derived from coronary computed tomography angiography revascularization planner (FFRCT Planner). OBJECTIVES: The aim of this study was to validate the accuracy of the FFRCT Planner. METHODS: In this multicenter, investigator-initiated, prospective study, patients with chronic coronary syndromes and significant lesions based on invasive FFR ≤0.80 were recruited. The FFRCT Planner was applied to the fractional flow reserve derived from coronary computed tomography angiography (FFRCT) model, simulating PCI. The primary objective was the agreement between the predicted post-PCI FFR by the FFRCT Planner and measured post-PCI FFR. Accuracy of the FFRCT Planner's luminal dimensions was assessed by using post-PCI optical coherence tomography as the reference. RESULTS: Overall, 259 patients were screened, with 120 patients (123 vessels) included in the final analysis. The mean patient age was 64 ± 9 years, and 24% had diabetes. Measured FFR post-PCI was 0.88 ± 0.06, and the FFRCT Planner FFR was 0.86 ± 0.06 (mean difference: 0.02 ± 0.07 FFR unit; limits of agreement: -0.12 to 0.15). Optical coherence tomography minimal stent area was 5.60 ± 2.01 mm2, and FFRCT Planner minimal stent area was 5.0 ± 2.2 mm2 (mean difference: 0.66 ± 1.21 mm2; limits of agreement: -1.7 to 3.0). The accuracy and precision of the FFRCT Planner remained high in cases with focal and diffuse disease and with low and high calcium burden. CONCLUSIONS: The FFRCT-based technology was accurate and precise for predicting FFR after PCI. (Precise Percutaneous Coronary Intervention Plan Study [P3]; NCT03782688).

Quantitative measurement of the histological features of alpha-1 antitrypsin deficiency-associated liver disease in biopsy specimens.

BACKGROUND: Pathological mutations in Alpha-1 Antitrypsin (AAT) protein cause retention of toxic polymers in the hepatocyte endoplasmic reticulum. The risk for cirrhosis in AAT deficiency is likely directly related to retention of these polymers within the liver. Polymers are classically identified on liver biopsy as inclusion bodies by periodic acid schiff staining after diastase treatment and immunohistochemistry. However, characterization of the polymer burden within a biopsy sample is limited to a semi-quantitative scale as described by a pathologist. Better methods to quantify polymer are needed to advance our understanding of pathogenesis of disease. Therefore, we developed a method to quantify polymer aggregation from standard histologic specimens. In addition, we sought to understand the relationship of polymer burden and other histologic findings to the presence of liver fibrosis. METHODS: Liver samples from a well-categorized AATD cohort were used to develop histo-morphometric tools to measure protein aggregation. RESULTS: Whole-slide morphometry reliably quantifies aggregates in AATD individuals. Despite very low levels of inclusions present (0-0.41%), accumulation of globules is not linear and is associated with higher fibrosis stages. Immunohistochemistry demonstrates that fibrosis is associated with polymer accumulation and not total AAT. A proportion of patients were found to be "heavy accumulators" with a polymer burden above the upper 25% of normal distribution. Males had significantly more liver inclusions and polymer than females. These measurements also highlight interrelated phenotypes of hepatocellular degeneration and autophagy in AATD liver disease. CONCLUSION: Quantitative inclusion analysis measures AAT accumulation in liver biopsy specimens. Quantification of polymer may identify individuals at risk for progressive disease and candidates for therapeutic interventions. Furthermore, these methods may be useful for evaluating efficacy of drugs targeting accumulation of AAT.

Clinical and histologic features of adults with alpha-1 antitrypsin deficiency in a non-cirrhotic cohort.

BACKGROUND & AIMS: Alpha-1 antitrypsin deficiency (AATD) is an uncommonly recognized cause of liver disease in adults, with descriptions of its natural history limited to case series and patient-reported data from disease registries. Liver pathology is limited to selected patients or unavailable. Therefore, we aimed to determine the prevalence and severity of liver fibrosis in an adult AATD population who were not known to have cirrhosis, while defining risk factors for fibrosis and testing non-invasive markers of disease. METHODS: A total of 94 adults with classic genotype 'PI*ZZ' AATD were recruited from North America and prospectively enrolled in the study. Liver aminotransferases and markers of synthetic function, transient elastography, and liver biopsy were performed. RESULTS: The prevalence of clinically significant liver fibrosis (F ≥ 2) was 35.1%. Alanine aminotransferase, aspartate aminotransferase and gamma-glutamyltransferase values were higher in the F ≥ 2 group. Metabolic syndrome was associated with the presence of clinically significant fibrosis (OR 14.2; 95% CI 3.7-55; p <0.001). Additionally, the presence of accumulated abnormal AAT in hepatocytes, portal inflammation, and hepatocellular degeneration were associated with clinically significant fibrosis. The accuracy of transient elastography to detect F ≥ 2 fibrosis was fair, with an AUC of 0.70 (95% CI 0.58-0.82). CONCLUSIONS: Over one-third of asymptomatic and lung affected adults with 'PI*ZZ' AATD have significant underlying liver fibrosis. Liver biopsies demonstrated variable amounts of accumulated Z AAT. The risk of liver fibrosis increases in the presence of metabolic syndrome, accumulation of AAT in hepatocytes, and portal inflammation on baseline biopsy. The results support the hypothesis that liver disease in this genetic condition may be related to a "toxic gain of function" from accumulation of AAT in hepatocytes. LAY SUMMARY: Individuals diagnosed with classic alpha-1 antitrypsin deficiency (ZZ) are at risk of liver injury and scarring, because of the accumulation of abnormal alpha-1 antitrypsin in the liver. A liver biopsy in ZZ individuals can demonstrate the accumulation of alpha-1 antitrypsin within the liver and identify if any associated liver scarring is present. Indviduals with large amounts of alpha-1 antitrypsin on biopsy may be at risk of liver injury and fibrosis. Additional common medical conditions of diabetes, obesity, high cholesterol, and hypertension (known as metabolic syndrome) are associated with a greater degree of liver injury. CLINICAL TRIAL NUMBER: clinicaltrials.gov NCT01810458.

Interobserver Agreement in the Diagnosis of Inflammatory Bowel Disease-Associated Neoplasia in China in Comparison to Subspecialized American Gastrointestinal Pathologists.

BACKGROUND: The aim of this study was to evaluate the interobserver variability in diagnosing inflammatory bowel disease (IBD)-associated neoplasia among practicing pathologists from China using telepathology, a practice of remote diagnostic consultation increasingly used nationally and internationally, and its comparison with the interpretation of subspecialized gastrointestinal (GI) pathologists from the United States (US). METHODS: Eight GI pathologists from the US and 4 pathologists from China with an interest in GI pathology participated in this study. A total of 50 colonic biopsies from patients with a clinical history of IBD from 8 medical centers in China were included. All microscopic slides in each case were digitized using an Aperio system. One pathologist (XL) reviewed the digitized full-slide images, and selected areas of interest were captured at low, medium, and high magnifications at a resolution of 1712 × 1072 pixels and saved as tagged image file format (TIFF) files on read-only DVD. Each pathologist evaluated the images and selected the most appropriate diagnostic category for each case (negative, indefinite, low-grade dysplasia [LGD], high-grade dysplasia [HGD], and carcinoma). A Fleiss' kappa coefficient (K) analysis was performed to determine interobserver agreement and the agreement of each pathologist from China with the consensus diagnosis (defined as diagnostic agreement by at least 4 participating US GI pathologists). RESULTS: There was substantial interobserver agreement among 4 pathologists from China on the interpretation of IBD-associated neoplasia (kappa value 0.68, 95% confidence interval: 0.56-0.78). A consensus diagnosis included negative (n = 22), LGD (n = 22), HGD (n = 3), carcinoma (n = 2), and indefinite for dysplasia (n = 1). Using consensus diagnoses as references, the agreement between each pathologist from China and the consensus diagnosis was substantial with kappa values ranging from 0.75 to 0.80. CONCLUSIONS: This study reveals substantial interobserver agreement for the interpretation of colonic neoplasia in IBD using digitized images among Chinese pathologists as well as between each Chinese pathologist and a consensus diagnosis generated by US GI pathologists.

Angiosomal radiopathologic analysis of transarterial radioembolization for the treatment of hepatocellular carcinoma.

PURPOSE: To assess the radiopathologic correlation following Yttrium-90 transarterial radioembolization (TARE) of hepatocellular carcinoma (HCC) using variable radiodosimetry to identify imaging surrogates of histologic response. METHODS: Twelve patients with HCC underwent ablative (≥ 190 Gy) and/or non-ablative (< 190 Gy) TARE delivered in a segmental, lobar, or combined fashion as a surgical neoadjuvant or bridge to transplantation. Both targeted tumor and treatment angiosome were analyzed before and after TARE utilizing hepatocyte-specific contrast-enhanced MRI or contrast-enhanced CT. Responses were graded using EASL and mRECIST criteria. Histologic findings including percent tumor necrosis and adjacent hepatic substrate effects were correlated with imaging features. RESULTS: Complete pathologic necrosis (CPN) was observed in 7/12 tumors post-TARE. Ablative and non-ablative dosing resulted in CPN in 5/6 and 2/6 tumors, respectively. Hyperintensity on T2-weighted imaging, the absence of hepatocyte-specific gadolinium contrast uptake, and plateau or persistent enhancement kinetics in the angiosome correlated with CPN and performed similarly to EASL and mRECIST criteria in predicting CPN. CONCLUSIONS: The absence of hepatocyte-specific contrast uptake, increased signal on T2-weighted sequences, and plateau or persistent enhancement in the angiosome may represent MRI surrogates of CPN following TARE of HCC. These findings correlated with EASL and mRECIST response criteria. Further investigation is needed to determine the role of these findings as possible adjuncts to conventional imaging criteria.

Neoadjuvant transarterial radiation lobectomy for colorectal hepatic metastases: a small cohort analysis on safety, efficacy, and radiopathologic correlation.

Colorectal cancer patients have a high incidence of liver metastasis (ml-CRC). Surgical resection is the gold standard for treatment of hepatic metastasis but only a small percent of patients are traditional candidates based on disease extent and adequate size of the future liver remnant (FLR). Interventions such as portal vein embolization (PVE) and associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) are performed to increase FLR for operative conversion. Limitations to PVE include intrahepatic disease progression, portal vascular invasion, and utilization with concurrent chemotherapy. ALPPS is associated with a high morbidly and mortality. Radiation lobectomy (RL) with yttrium-90 (Y-90) delivers transarterial ablative brachytherapy to the future hepatectomy site which generates FLR hypertrophy similar or greater than PVE. Early results indicate that RL is safe, effective, and may offer unique benefits by providing cytoreduction of hepatic metastases which extends FLR hypertrophy time and allows FLR surveillance to gauge disease biology. A retrospective analysis of four patients with ml-CRC treated with RL prior to hepatectomy was performed to evaluate initial safety, efficacy, FLR hypertrophy, and radiopathologic correlation. Adverse events after RL and hepatectomy were evaluated. Imaging findings were analyzed for efficacy defined as FLR hypertrophy and disease control. Radiopathologic correlation was performed after histologic analysis. RL was well tolerated without major adverse events or hepatic decompensation. FLR hypertrophy ranged from 24.9% to 119% at mean follow-up of three months. The majority of complications were related to surgical instrumentation of the FLR due to upstaging at time of surgery. Hepatectomy specimen histology demonstrated complete pathologic response in 50% of patients, 50% radiopathologic concordance rate, and no significant hepatic fibrosis. Initial experience with neoadjuvant RL for ml-CRC is safe and provides both durable disease control and FLR hypertrophy with concurrent chemotherapy. A 50% complete pathologic response rate raises the possibility of definitive chemoradiation in poor surgical candidates. Prospective investigation is required.

Postural orientation and equilibrium processes associated with increased postural sway in autism spectrum disorder (ASD).

BACKGROUND: Increased postural sway has been repeatedly documented in children with autism spectrum disorder (ASD). Characterizing the control processes underlying this deficit, including postural orientation and equilibrium, may provide key insights into neurophysiological mechanisms associated with ASD. Postural orientation refers to children's ability to actively align their trunk and head with respect to their base of support, while postural equilibrium is an active process whereby children coordinate ankle dorsi-/plantar-flexion and hip abduction/adduction movements to stabilize their upper body. Dynamic engagement of each of these control processes is important for maintaining postural stability, though neither postural orientation nor equilibrium has been studied in ASD. METHODS: Twenty-two children with ASD and 21 age and performance IQ-matched typically developing (TD) controls completed three standing tests. During static stance, participants were instructed to stand as still as possible. During dynamic stances, participants swayed at a comfortable speed and magnitude in either anterior-posterior (AP) or mediolateral (ML) directions. The center of pressure (COP) standard deviation and trajectory length were examined to determine if children with ASD showed increased postural sway. Postural orientation was assessed using a novel virtual time-to-contact (VTC) approach that characterized spatiotemporal dimensions of children's postural sway (i.e., body alignment) relative to their postural limitation boundary, defined as the maximum extent to which each child could sway in each direction. Postural equilibrium was quantified by evaluating the amount of shared or mutual information of COP time series measured along the AP and ML directions. RESULTS: Consistent with prior studies, children with ASD showed increased postural sway during both static and dynamic stances relative to TD children. In regard to postural orientation processes, children with ASD demonstrated reduced spatial perception of their postural limitation boundary towards target directions and reduced time to correct this error during dynamic postural sways but not during static stance. Regarding postural equilibrium, they showed a compromised ability to decouple ankle dorsi-/plantar-flexion and hip abduction/adduction processes during dynamic stances. CONCLUSIONS: These results suggest that deficits in both postural orientation and equilibrium processes contribute to reduced postural stability in ASD. Specifically, increased postural sway in ASD appears to reflect patients' impaired perception of their body movement relative to their own postural limitation boundary as well as a reduced ability to decouple distinct ankle and hip movements to align their body during standing. Our findings that deficits in postural orientation and equilibrium are more pronounced during dynamic compared to static stances suggests that the increased demands of everyday activities in which children must dynamically shift their COP involve more severe postural control deficits in ASD relative to static stance conditions that often are studied. Systematic assessment of dynamic postural control processes in ASD may provide important insights into new treatment targets and neurodevelopmental mechanisms.

Common Inflammatory Disorders and Neoplasia of the Ileal Pouch: A Review of Histopathology.

Ileal pouch-anal anastomosis (IPAA) is the standard restorative procedure after proctocolectomy in patients with ulcerative colitis (UC) who require colectomy. The ileal pouch is susceptible to a variety of insults including mechanical injury, ischemia, fecal stasis, and infectious agents. In addition, the development of recurrent and idiopathic inflammatory bowel disease and neoplasia may occur in the ileal pouch. Although clinical, endoscopic, and radiographic examination can diagnose many ileal pouch diseases, histologic examination plays an essential role in diagnosis and management, particularly in cases with antibiotic refractory chronic pouchitis and pouch neoplasia.

Tofacitinib for the treatment of tumor necrosis factor-α inhibitor refractory esophageal Crohn's disease: a case report.

BACKGROUND: Esophageal Crohn's disease is reported as a rare manifestation, although its prevalence may be underestimated because upper endoscopies are not routinely performed in asymptomatic adults. Tofacitinib, an oral janus kinase inhibitor, is a new biologic that has shown promise in the treatment of ulcerative colitis and may be effective in the treatment of Crohn's disease according to phase 2 trials. We report the first case of esophageal Crohn's disease successfully treated with tofacitinib in a patient with worsening symptoms despite maintenance therapy with a tumor necrosis factor-α inhibitor. CASE PRESENTATION: A 67-year-old Caucasian woman presented with new dysphagia and had findings of esophageal Crohn's disease on endoscopy. The dosage of her current biologic therapy-adalimumab-was increased in frequency, without improvement. Our patient was started on tofacitinib and demonstrated an improvement in symptoms, with a repeat endoscopy showing resolution of the previous lesions. CONCLUSION: Esophageal Crohn's disease is likely underdiagnosed but is an important consideration in a patient with new symptoms of dysphagia and known Crohn's disease. Tofacitinib, while a novel agent, could have a role in the treatment of esophageal Crohn's disease that does not improve with intensification of the current biologic therapy. It provides a different mechanism in patients who become refractory to maintenance therapy.

Atypical presentation of a hepatic artery pseudoaneurysm: A case report and review of the literature.

Classically, hepatic artery pseudoaneurysms (HAPs) arise secondary to trauma or iatrogenic causes. With an increasing prevalence of laparoscopic procedures of the hepatobiliary system the risk of inadvertent injury to arterial vessels is increased. Pseudoaneurysm formation post injury can lead to serious consequences of rupture and subsequent hemorrhage, therefore intervention in all identified visceral pseudoaneurysms has been advocated. A variety of interventional methods have been proposed, with surgical management becoming the last step intervention when minimally invasive therapies have failed. The authors present a case of a HAP in a 56-year-old female presenting with jaundice and pruritis suggestive of a Klatskin's tumor. This presentation of HAP in a patient without any significant past medical or surgical intervention is atypical when considering that the majority of HAP cases present secondary to iatrogenic causes or trauma. Multiple minimally invasive approaches were employed in an attempt to alleviate the symptomology which included jaundice and associated inflammatory changes. Ultimately, a right hepatic trisegmentectomy was required to adequately relieve the mass effect on biliary outflow obstruction and definitively address the HAP. The presentation of a HAP masquerading as a malignancy with jaundice and pruritis, rather than the classic symptoms of abdominal pain, anemia, and melena, is unique. This presentation is only further complicated by the absent history of either trauma or instrumentation. It is important to be aware of HAPs as a potential cause of jaundice in addition to the more commonly thought of etiologies. Furthermore, given the morbidity and mortality associated with pseudoaneurysm rupture, intervention in identifiable cases, either by minimally invasive or surgical interventions, is recommended.

EGFR family and cMet expression profiles and prognostic significance in esophagogastric adenocarcinoma.

BACKGROUND: Targeted therapy with anti-human epidermal growth factor receptor-2 (HER2) monoclonal antibody in patients with HER2 overexpressed esophagogastric adenocarcinoma (EGA) improves survival; however, the effect is transient due to the development of resistance. Some studies suggest that cMet overexpression provides cross talk for epidermal growth factor receptor (EGFR) and HER2 inhibition. We sought to characterize the expression profile of the EGFR family and cMet receptors in untreated, resected EGA. METHODS: This retrospective analysis included all sequential patients with esophageal or gastroesophageal junction (GEJ) adenocarcinoma who underwent primary resection, without neoadjuvant therapy or HER2 inhibition, with adequate tissue, at the University of Florida from 2001 to 2011. Central blinded immunohistochemistry (IHC) was performed on tumor specimens with EGFR, HER2, HER3, HER4 and cMet expression scored as low (0, 1+) or high (2+, 3+). Demographic and tumor characteristics were compared using Fisher exact test. Kaplan-Meier curves and univariate analysis compared survival among different receptors. RESULTS: Total 52 patients were included in the study with median age 66 years. High expression of EGFR (73%), HER2 (40%), HER3 (75%), HER4 (35%) and cMet (69%) was detected among the study group. HER3 and HER4 co-expression was found in 18 (35%) cases. Pan expression of all four EGFR family members with cMet was noted in only 17% of cases. On univariate analysis, tumor stage and depth correlated with survival, while cMet + HER3 +/- EGFR receptor co-expression trended towards a worse survival. CONCLUSIONS: EGFR family and cMet are frequently co-expressed in treatment naïve resected EGA or GEJ tumors. Although our data do not significantly show receptor status as a prognostic factor, the co-expression profiles support for further investigation to improve targeting of this signal transduction axis.

Volumetric changes in cranial vault expansion: comparison of fronto-orbital advancement and posterior cranial vault distraction osteogenesis.

BACKGROUND: Posterior cranial vault distraction osteogenesis has recently been introduced to treat patients with multisuture syndromic craniosynostosis and is believed to provide greater gains in intracranial volume. This study provides volumetric analysis to determine the gains in intracranial volume produced by this modality. METHODS: This was a two-center retrospective study of preprocedure and postprocedure computed tomography scans of two groups of 15 patients each with syndromic multisuture craniosynostosis treated with either fronto-orbital advancement or posterior cranial vault distraction osteogenesis. Scan data were analyzed volumetrically with Mimics software. Volumetric gains attributable to growth between scans were controlled for. RESULTS: The mean advancements were 12.5 mm for fronto-orbital advancement and 24.8 mm for distraction osteogenesis. The mean difference in volume between the preoperative and postoperative scans was 144 cm(3) for fronto-orbital advancement and 274 cm(3) for (p = 0.009). After controlling for growth, the corrected mean volume difference was 66 cm(3) for fronto-orbital advancement and 142 cm(3) for distraction osteogenesis (p = 0.0017). The corrected mean volume difference per millimeter of advancement was 4.6 cm(3) for fronto-orbital advancement and 5.8 cm(3) for distraction (p = 0.357). CONCLUSIONS: In this retrospective study, posterior cranial vault distraction osteogenesis provided statistically greater intracranial volume expansion than fronto-orbital advancement. The volume gains per millimeter advancement were similar between groups, with a trend toward greater gains per millimeter with distraction osteogenesis. Gradual expansion of the overlying soft tissues with posterior cranial vault distraction osteogenesis appears to be the primary mechanism for greater volume gains with this technique. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

Apparent elastic modulus and hysteresis of skeletal muscle cells throughout differentiation.

The effect of differentiation on the transverse mechanical properties of mammalian myocytes was determined by using atomic force microscopy. The apparent elastic modulus increased from 11.5 +/- 1.3 kPa for undifferentiated myoblasts to 45.3 +/- 4.0 kPa after 8 days of differentiation (P < 0.05). The relative contribution of viscosity, as determined from the normalized hysteresis area, ranged from 0.13 +/- 0.02 to 0.21 +/- 0.03 and did not change throughout differentiation. Myosin expression correlated with the apparent elastic modulus, but neither myosin nor beta-tubulin were associated with hysteresis. Microtubules did not affect mechanical properties because treatment with colchicine did not alter the apparent elastic modulus or hysteresis. Treatment with cytochalasin D or 2,3-butanedione 2-monoxime led to a significant reduction in the apparent elastic modulus but no change in hysteresis. In summary, skeletal muscle cells exhibited viscoelastic behavior that changed during differentiation, yielding an increase in the transverse elastic modulus. Major contributors to changes in the transverse elastic modulus during differentiation were actin and myosin.