Diagnostic yield of CT head in delirium and altered mental status-A systematic review and meta-analysis.

BACKGROUND: CT head is commonly performed in the setting of delirium and altered mental status (AMS), with variable yield. We aimed to evaluate the yield of CT head in hospitalized patients with delirium and/or AMS across a variety of clinical settings and identify factors associated with abnormal imaging. METHODS: We included studies in adult hospitalized patients, admitted to the emergency department (ED) and inpatient medical unit (grouped together) or the intensive care unit (ICU). Patients had a diagnosis of delirium/AMS and underwent a CT head that was classified as abnormal or not. We searched Medline, Embase and other databases (informed by PRISMA guidelines) from inception until November 11, 2021. Studies that were exclusively performed in patients with trauma or a fall were excluded. A meta-analysis of proportions was performed; the pooled proportion of abnormal CTs was estimated using a random effects model. Heterogeneity was determined via the I2 statistic. Factors associated with an abnormal CT head were summarized qualitatively. RESULTS: Forty-six studies were included for analysis. The overall yield of CT head in the inpatient/ED was 13% (95% CI: 10.2%-15.9%) and in ICU was 17.4% (95% CI: 10%-26.3%), with considerable heterogeneity (I2 96% and 98% respectively). Heterogeneity was partly explained after accounting for study region, publication year, and representativeness of the target population. Yield of CT head diminished after year 2000 (19.8% vs. 11.1%) and varied widely depending on geographical region (8.4%-25.9%). The presence of focal neurological deficits was a consistent factor that increased yield. CONCLUSION: Use of CT head to diagnose the etiology of delirium and AMS varied widely and yield has declined. Guidelines and clinical decision support tools could increase the appropriate use of CT head in the diagnostic etiology of delirium/AMS.

The determinants of maternal homocysteine in pregnancy: findings from the Ottawa and Kingston Birth Cohort.

OBJECTIVE: Observational studies have linked elevated homocysteine to vascular conditions. Folate intake has been associated with lower homocysteine concentration, although randomised controlled trials of folic acid supplementation to decrease the incidence of vascular conditions have been inconclusive. We investigated determinants of maternal homocysteine during pregnancy, particularly in a folic acid-fortified population. DESIGN: Data were from the Ottawa and Kingston Birth Cohort of 8085 participants. We used multivariable regression analyses to identify factors associated with maternal homocysteine, adjusted for gestational age at bloodwork. Continuous factors were modelled using restricted cubic splines. A subgroup analysis examined the modifying effect of MTHFR 677C>T genotype on folate, in determining homocysteine concentration. SETTING: Participants were recruited in Ottawa and Kingston, Canada, from 2002 to 2009. PARTICIPANTS: Women were recruited when presenting for prenatal care in the early second trimester. RESULTS: In 7587 participants, factors significantly associated with higher homocysteine concentration were nulliparous, smoking and chronic hypertension, while factors significantly associated with lower homocysteine concentration were non-Caucasian race, history of a placenta-mediated complication and folic acid supplementation. Maternal age and BMI demonstrated U-shaped associations. Folic acid supplementation of >1 mg/d during pregnancy did not substantially increase folate concentration. In the subgroup analysis, MTHFR 677C>T modified the effect of folate status on homocysteine concentration. CONCLUSIONS: We identified determinants of maternal homocysteine relevant to the lowering of homocysteine in the post-folic acid fortification era, characterised by folate-replete populations. A focus on periconceptional folic acid supplementation and improving health status may form an effective approach to lower homocysteine.

The role of maternal homocysteine concentration in placenta-mediated complications: findings from the Ottawa and Kingston birth cohort.

BACKGROUND: Homocysteine is an intermediate metabolite implicated in the risk of placenta-mediated complications, including preeclampsia, placental abruption, fetal growth restriction, and pregnancy loss. Large cohort and case-control studies have reported inconsistent associations between homocysteine and these complications. The purpose of this study was to investigate whether elevated maternal plasma homocysteine concentration in the early to mid-second trimester is associated with an increased risk of placenta-mediated complications. We examined the following potential moderating factors that may explain discrepancies among previous studies: high-risk pregnancy and the MTHFR 677C>T polymorphism. METHODS: We analyzed data from participants recruited to the Ottawa and Kingston (OaK) Birth Cohort from 2002 to 2009 in Ottawa and Kingston, Canada. The primary outcome was a composite of any placenta-mediated complication, defined as a composite of small for gestational age (SGA) infant, preeclampsia, placental abruption, and pregnancy loss. Secondary outcomes were, individually: SGA infant, preeclampsia, placental abruption, and pregnancy loss. We conducted multivariable logistic regression analyses with homocysteine as the primary continuous exposure, adjusting for gestational age at the time of bloodwork and explanatory maternal characteristics. The functional form, i.e., the shape of the homocysteine association with the outcome was examined using restricted cubic splines and information criteria (Akaike's/Bayesian Information Criterion statistics). Missing data were handled with multiple imputation. RESULTS: 7587 cohort participants were included in the study. Maternal plasma homocysteine concentration was significantly associated (linearly) with an increased risk of both the composite outcome of any placenta-mediated complication (p = 0.0007), SGA (p = 0.0010), severe SGA, and marginally with severe preeclampsia, but not preeclampsia, placental abruption and pregnancy loss. An increase in homocysteine concentration significantly increased the odds of any placenta-mediated complication (odds ratio (OR) for a 5 µmol/L increase: 1.63, 95% Confidence Interval (CI) 1.23-2.16) and SGA (OR 1.76, 95% CI 1.25-2.46). Subgroup analyses indicated some potential for modifying effects of the MTHFR 677C>T genotype and high-risk pregnancy, although the interaction was not statistically significant (high-risk subgroup OR 2.37, 95% CI 1.24-4.53, p-value for interaction =0.14). CONCLUSIONS: Our results suggest an independent effect of early to mid-pregnancy elevated maternal homocysteine on placenta-mediated pregnancy complications.

Imaging features of pure and mixed forms of mucinous breast carcinoma with histopathological correlation.

METHODS:: A cross-sectional study identified cases of mucinous breast carcinoma from pathology records (2004-2012). Two radiologists classified imaging features by consensus and two pathologists classified cases into pure or mixed subtypes. Bi-variable analyses were performed using relevant statistical tests. RESULTS:: We identified 80 lesions in 77 female patients (median age 65 years, range 29-88): 58 lesions on mammograhy, 72 on ultrasound, and 25 on MRI. Statistically significant findings (p < 0.05) are as follows. On mammography, tumour margins tended to be indistinct (12, 48%) and spiculated (11, 44%) for pure and mixed lesions, respectively. Pure mucinous masses were less microcalcified (23, 77%) and mixed masses equally so. On ultrasound, pure tumours tended towards an irregular or oval shape (44, 42%) with mixed tumours having an irregular shape (78%). More pure tumours (53%) had posterior acoustic enhancement than mixed lesions (33%), and all pure tumours lacked posterior acoustic shadowing. Pure lesions had a heterogeneous echo pattern more than mixed tumours (78% vs 39%). On MRI, pure tumours tended towards a persistent kinetic curve (42%) whereas mixed tumours predominantly had a washout pattern (75%). Most pure tumours were T2 hyperintense (83%) whereas mixed lesions were T2 isointense or hyperintense (61%, 23%), respectively. CONCLUSION:: An analysis of imaging features can help to infer underlying histology of pure and mixed forms of mucinous breast carcinoma. ADVANCES IN KNOWLEDGE:: Pure mucinous carcinomas present less suspicious imaging features than mixed mucinous carcinomas and could be mistaken for non malignant lesions. An imaging analysis of mucinous breast carcinoma can help infer their underlying histology.

Early recognition and diagnosis of Ewing sarcoma of the cervical spine.

Ewing sarcoma of the cervical spine is a rare diagnosis. Early recognition and treatment of this condition improves survival. Reported is a case of a 20-year-old male patient who presented with increasing neck pain. Computed tomography and magnetic resonance imaging showed a mass with a primary differential diagnosis of Ewing sarcoma. As a result of mass effect and spinal cord compression, immediate medical intervention was deemed necessary to prevent neurologic deficits.

Perforated cecal diverticulitis with CT diagnosis and medical management.

Acute diverticulitis is a painful condition of the gastrointestinal tract that results from sudden inflammation of one or more diverticula in the bowel wall. Right-sided acute diverticulitis, such as cecal diverticulitis, is uncommon diagnosis that can be easily misdiagnosed as acute appendicitis as it shares similar clinical presentation. An unusual complication of right-sided acute diverticulitis such as perforated cecal diverticulitis has different management from acute appendicitis. Thus, definitive diagnosis of this clinical condition with imaging is crucial to optimal management. We report a case of 43-year-old man who presented to the Emergency Department with acute onset severe right lower quadrant abdominal pain associated with anorexia, fever, and nausea. Computed tomography scans obtained showed findings consistent with perforated diverticulitis limited to the cecum, and normal caliber appendix. Conservative medical treatment was decided based on localized imaging findings with excellent outcome.

The Pathophysiology and Management of Coprophagia: A Report of Two Cases and Literature Review.

Coprophagia is a rare and distressing disorder characterized by symptoms of compulsive consumption of feces. Several attempts have been made in literature to explore the pathophysiology, management, and outcomes of this disorder. However, critical questions remain, related to characterizing effective management, features of associated comorbidities, time to recovery of symptoms, sustainability of recovery, and the determinants of outcomes. Unfortunately, there is a dearth of available literature addressing these questions. We present two cases of patients with coprophagia in seeking to address these questions. Common symptoms of thought content disorder related to coprophagic behavior are noted in both cases. A shorter time to resolution of coprophagia is noted in one of the patients compared to previously reported studies. Recent and pertinent literature was reviewed and the implications for diagnosis and management of coprophagia are discussed.

Bilateral congenital absence of the internal carotid arteries: a case report.

Congenital absence of the internal carotid artery is a rare occurrence. Even more infrequent are cases where the patient has a bilateral absence of the internal carotid arteries. Reported is a case of a 52-year-old woman who presented with optic nerve neuropathy, and was incidentally discovered to have a congenital bilateral absence of her internal carotid arteries. During computed tomography angiography imaging looking for cerebral venous thrombosis, related to her preexisting condition of bilateral elevated optic discs and residual left optic neuropathy, the findings were made. The absence of the arteries is not always recognizably symptomatic, with most findings being incidental through imaging studies only. This is because collateral flow allows for sufficient cerebral circulation. However, this condition puts such patients at higher risk for conditions such as aneurysms and subsequently strokes where the collateral flow exists.

Serum and red-blood-cell folate demonstrate differential associations with BMI in pregnant women.

OBJECTIVE: To examine the association between BMI and folate concentrations in serum and red blood cells (RBC) in pregnant women. DESIGN: A cross-sectional comparison of folate concentrations in serum and RBC sampled simultaneously from the same individual. SETTING: The Ottawa Hospital and Kingston General Hospital, Ontario, Canada. SUBJECTS: Pregnant women recruited between 12 and 20 weeks of gestation. RESULTS: A total of 869 pregnant women recruited from April 2008 to April 2009 were included in the final analysis. Serum folate was inversely associated and RBC folate positively associated with BMI, after adjusting for folic acid supplementation, age, gestational age at blood sample collection, race, maternal education, annual income, smoking and MTHFR 677C→T genotype. In stratified analyses, this differential association was significant in women with the MTHFR CC variant. In women with the CT and TT variants, the differential associations were in the same direction but not significant. Folic acid supplementation during pregnancy did not alter the differential association of BMI with serum and RBC folate concentration. This indicates that the current RBC folate cut-off approach for assessing risk of neural tube defects in obese women may be limited. CONCLUSIONS: BMI is inversely associated with serum folate and positively associated with RBC folate in pregnant women, especially for those with the MTHFR CC variant.

Mail merge can be used to create personalized questionnaires in complex surveys.

BACKGROUND: Low response rates and inadequate question comprehension threaten the validity of survey results. We describe a simple procedure to implement personalized-as opposed to generically worded-questionnaires in the context of a complex web-based survey of corresponding authors of a random sample of 300 published cluster randomized trials. The purpose of the survey was to gather more detailed information about informed consent procedures used in the trial, over and above basic information provided in the trial report. We describe our approach-which allowed extensive personalization without the need for specialized computer technology-and discuss its potential application in similar settings. RESULTS: The mail merge feature of standard word processing software was used to generate unique, personalized questionnaires for each author by incorporating specific information from the article, including naming the randomization unit (e.g., family practice, school, worksite), and identifying specific individuals who may have been considered research participants at the cluster level (family doctors, teachers, employers) and individual level (patients, students, employees) in questions regarding informed consent procedures in the trial. The response rate was relatively high (64%, 182/285) and did not vary significantly by author, publication, or study characteristics. The refusal rate was low (7%). CONCLUSION: While controlled studies are required to examine the specific effects of our approach on comprehension, quality of responses, and response rates, we showed how mail merge can be used as a simple but useful tool to add personalized fields to complex survey questionnaires, or to request additional information required from study authors. One potential application is in eliciting specific information about published articles from study authors when conducting systematic reviews and meta-analyses.

Survey of consent practices in cluster randomized trials: improvements are needed in ethical conduct and reporting.

BACKGROUND: Informed consent procedures in cluster randomized trials (CRTs) are considerably more complicated than in individually randomized trials. In a CRT, the units of randomization, intervention, and observation may differ in a single trial; there can be multiple levels of participants (individual and cluster level); consent may be required separately for intervention and data collection; and there may be practical constraints to seeking informed consent, for example, due to cluster-level interventions or the sheer size of clusters. PURPOSE: We aimed to document consent practices at individual and cluster levels, assess the adequacy of reporting consent in trial publications, and assess associations with two trial characteristics that may influence consent requirements in CRTs: presence or absence of study interventions and presence or absence of data collection procedures at individual and cluster levels. METHODS: We reviewed a random sample of 300 CRTs published during 2000-2008. We sent survey questionnaires to 285 unique authors of these trials to gather detailed information about consent procedures used in each trial. RESULTS: In all, 182 authors (64%) responded. Overall, 93% (95% confidence interval (CI): 88.8%-96.6%) indicated that participant consent had been sought for some aspects of the study. Consent was less frequently sought for a study intervention (70% of respondents) than for data collection (88%). More than half of the respondents (52%) indicated that consent had been sought at both cluster and individual levels. There was strong evidence for under-reporting of consent in trial publications: only 63% of all trial publications reported that informed consent had been sought for some aspect of the study. The odds ratios (ORs) summarizing the association of the two trial characteristics with cluster-level participant consent were weak (OR = 1.17, p = 0.70 for presence of cluster-level study intervention and OR = 1.54, p = 0.29 for data collection); on the other hand, the ORs summarizing the associations with individual-level consent were strong (OR = 6.2, p < 0.0001 for presence of individual-level intervention and OR = 14.7, p < 0.0001 for data collection). LIMITATIONS: In all, 36% of authors did not respond to the survey; to the extent that consent practices in their trials were different than in respondents' trials, our results may be biased. CONCLUSIONS: There is a need for improvements in research practices in CRTs as well as their reporting. There may be a lack of clarity about consent requirements at the cluster level in particular. With the publication of the Ottawa Statement on the Ethical Design and Conduct of Cluster Randomized Trials, researchers and research ethics committees now have access to comprehensive ethics guidelines specific to CRTs.

Challenges in the research ethics review of cluster randomized trials: international survey of investigators.

BACKGROUND: Cluster randomized trials (CRTs) complicate the interpretation of standard research ethics guidelines for several reasons. For one, the units of allocation, intervention, and observation often may differ within a single trial. In the absence of tailored and internationally accepted ethics guidelines for CRTs, researchers and research ethics committees have no common standard by which to judge ethically appropriate practices in CRTs. Moreover, lack of familiarity with and consideration of the unique features of the CRT design by research ethics committees may cause difficulties in the research ethics review process, and amplify problems such as variability in the requirements and decisions reached by different research ethics committees. PURPOSE: We aimed to characterize research ethics review of CRTs, examine investigator experiences with the ethics review process, and assess the need for ethics guidelines for CRTs. METHODS: An electronic search strategy implemented in MEDLINE was used to identify and randomly sample 300 CRTs published in English language journals from 2000 to 2008. A web-based survey with closed- and open-ended questions was administered to corresponding authors in a series of six contacts. RESULTS: The survey response rate was 64%. Among 182 of 285 eligible respondents, 91% indicated that they had sought research ethics approval for the identified CRT, although only 70% respondents reported research ethics approval in the published article. Nearly one-third (31%) indicated that they have had to meet with ethics committees to explain aspects of their trials, nearly half (46%) experienced variability in the ethics review process in multijurisdictional trials, and 38% experienced negative impacts of the ethics review process on their trials, including delays in trial initiation (28%), increased costs (10%), compromised ability to recruit participants (16%), and compromised methodological quality (9%). Most respondents (74%; 95% confidence interval (CI): 67%-80%) agreed or strongly agreed that there is a need to develop ethics guidelines for CRTs, and (70%; 95% CI: 63%-77%) that ethics committees could be better informed about distinct ethical issues surrounding CRTs. LIMITATIONS: Thirty-six percent of authors did not respond to the survey. Due to the absence of comparable results from a representative sample of authors of individually randomized trials, it is unclear to what extent the reported challenges result from the CRT design. CONCLUSIONS: CRT investigators are experiencing challenges in the research ethics review of their trials, including excessive delays, variability in process and outcome, and imposed requirements that can have negative consequences for study conduct. Investigators identified a clear need for ethics guidelines for CRTs and education of research ethics committees about distinct ethical issues in CRTs.

Researchers' perceptions of ethical challenges in cluster randomized trials: a qualitative analysis.

BACKGROUND: Cluster randomized trials (CRTs) pose ethical challenges for investigators and ethics committees. This study describes the views and experiences of CRT researchers with respect to: (1) ethical challenges in CRTs; (2) the ethics review process for CRTs; and (3) the need for comprehensive ethics guidelines for CRTs. METHODS: Descriptive qualitative analysis of interviews conducted with a purposive sample of 20 experienced CRT researchers. RESULTS: Informants expressed concern over the potential for bias that may result from requirements to obtain informed consent from research participants in CRTs. Informants suggested that the need for informed consent ought to be related to the type of intervention under study in a CRT. Informants rarely expressed concern regarding risks to research participants in CRTs, other than risks to privacy. Important issues identified in the research ethics literature, including fair subject selection and other justice issues, were not mentioned by informants. The ethics review process has had positive and negative impacts on CRT conduct. Informants stated that variability in ethics review between jurisdictions, and increasingly stringent ethics review in recent years, have hampered their ability to conduct CRTs. Many informants said that comprehensive ethics guidelines for CRTs would be helpful to researchers and research ethics committees. CONCLUSIONS: Informants identified key ethical challenges in the conduct of CRTs, specifically relating to identifying subjects, seeking informed consent, and the use of gatekeepers. These data have since been used to identify topics for in-depth ethical analysis and to guide the development of comprehensive ethics guidelines for CRTs.

Assembly of fibrillin microfibrils governs extracellular deposition of latent TGF beta.

Control of the bioavailability of the growth factor TGFbeta is essential for tissue formation and homeostasis, yet precisely how latent TGFbeta is incorporated into the extracellular matrix is unknown. Here, we show that deposition of a large latent TGFbeta complex (LLC), which contains latent TGFbeta-binding protein 1 (LTBP-1), is directly dependent on the pericellular assembly of fibrillin microfibrils, which interact with fibronectin during higher-order fibrillogenesis. LTBP-1 formed pericellular arrays that colocalized with microfibrils, whereas fibrillin knockdown inhibited fibrillar LTBP-1 and/or LLC deposition. Blocking alpha5beta1 integrin or supplementing cultures with heparin, which both inhibited microfibril assembly, disrupted LTBP-1 deposition and enhanced Smad2 phosphorylation. Full-length LTBP-1 bound only weakly to N-terminal pro-fibrillin-1, but this association was strongly enhanced by heparin. The microfibril-associated glycoprotein MAGP-1 (MFAP-2) inhibited LTBP-1 binding to fibrillin-1 and stimulated Smad2 phosphorylation. By contrast, fibulin-4, which interacted strongly with full-length LTBP-1, did not induce Smad2 phosphorylation. Thus, LTBP-1 and/or LLC deposition is dependent on pericellular microfibril assembly and is governed by complex interactions between LTBP-1, heparan sulfate, fibrillin-1 and microfibril-associated molecules. In this way, microfibrils control TGFbeta bioavailability.

Collagen and glycopolymer based hydrogel for potential corneal application.

6-Methacryloyl-alpha-D-galactopyranose (MG) was synthesized, and characterized by Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectrometry, and single-crystal X-ray diffraction. A series of interpenetrating polymer network (IPN) hydrogels was fabricated by simultaneously photocuring MG crosslinked by poly(ethylene glycol) diacrylate and chemically crosslinking type I collagen with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide. The successful incorporation of the glycopolymer, polymer MG, into collagen hydrogel was confirmed by FTIR and solid-state (13)C NMR. The optical characteristics of the IPN hydrogels are comparable to those of human corneas. The tensile strength and modulus of the hydrogels are enhanced by incorporation of polymer MG in comparison to that of the control collagen hydrogel. Biodegradation results indicated that polymer MG enhanced the stability of the composite hydrogels against collagenase. In vitro results demonstrated that the IPN hydrogel supported the adhesion and proliferation of human corneal epithelial cells and outperformed human cornea in blocking bacteria adhesion. Taken together, the IPN hydrogel might be a promising material for use in corneal lamellar keratoplasty.

Ethical and policy issues in cluster randomized trials: rationale and design of a mixed methods research study.

BACKGROUND: Cluster randomized trials are an increasingly important methodological tool in health research. In cluster randomized trials, intact social units or groups of individuals, such as medical practices, schools, or entire communities--rather than individual themselves--are randomly allocated to intervention or control conditions, while outcomes are then observed on individual cluster members. The substantial methodological differences between cluster randomized trials and conventional randomized trials pose serious challenges to the current conceptual framework for research ethics. The ethical implications of randomizing groups rather than individuals are not addressed in current research ethics guidelines, nor have they even been thoroughly explored. The main objectives of this research are to: (1) identify ethical issues arising in cluster trials and learn how they are currently being addressed; (2) understand how ethics reviews of cluster trials are carried out in different countries (Canada, the USA and the UK); (3) elicit the views and experiences of trial participants and cluster representatives; (4) develop well-grounded guidelines for the ethical conduct and review of cluster trials by conducting an extensive ethical analysis and organizing a consensus process; (5) disseminate the guidelines to researchers, research ethics boards (REBs), journal editors, and research funders. METHODS: We will use a mixed-methods (qualitative and quantitative) approach incorporating both empirical and conceptual work. Empirical work will include a systematic review of a random sample of published trials, a survey and in-depth interviews with trialists, a survey of REBs, and in-depth interviews and focus group discussions with trial participants and gatekeepers. The empirical work will inform the concurrent ethical analysis which will lead to a guidance document laying out principles, policy options, and rationale for proposed guidelines. An Expert Panel of researchers, ethicists, health lawyers, consumer advocates, REB members, and representatives from low-middle income countries will be appointed. A consensus conference will be convened and draft guidelines will be generated by the Panel; an e-consultation phase will then be launched to invite comments from the broader community of researchers, policy-makers, and the public before a final set of guidelines is generated by the Panel and widely disseminated by the research team.

Fibrillin-1 microfibril deposition is dependent on fibronectin assembly.

Newly deposited microfibrils strongly colocalise with fibronectin in primary fibroblasts. Microfibril formation is grossly inhibited by fibronectin depletion, but rescued by supplementation with exogenous cellular fibronectin. As integrin receptors are key determinants of fibronectin assembly, we investigated whether they also influenced microfibril deposition. Analysis of beta1-integrin-receptor-null fibroblasts, blockage of cell surface integrin receptors that regulate fibronectin assembly and disruption of Rho kinase all result in suppressed deposition of both fibronectin and microfibrils. Antibody activation of beta1 integrins in fibronectin-depleted cultures is insufficient to rescue microfibril assembly. In fibronectin(RGE/RGE) mutant mouse fibroblast cultures, which do not engage alpha5beta1 integrin, extracellular assembly of both fibronectin and microfibrils is markedly reduced. Thus, pericellular microfibril assembly is regulated by fibronectin fibrillogenesis.

Fibrillin-1 regulates the bioavailability of TGFbeta1.

We have discovered that fibrillin-1, which forms extracellular microfibrils, can regulate the bioavailability of transforming growth factor (TGF) beta1, a powerful cytokine that modulates cell survival and phenotype. Altered TGFbeta signaling is a major contributor to the pathology of Marfan syndrome (MFS) and related diseases. In the presence of cell layer extracellular matrix, a fibrillin-1 sequence encoded by exons 44-49 releases endogenous TGFbeta1, thereby stimulating TGFbeta receptor-mediated Smad2 signaling. This altered TGFbeta1 bioavailability does not require intact cells, proteolysis, or the altered expression of TGFbeta1 or its receptors. Mass spectrometry revealed that a fibrillin-1 fragment containing the TGFbeta1-releasing sequence specifically associates with full-length fibrillin-1 in cell layers. Solid-phase and BIAcore binding studies showed that this fragment interacts strongly and specifically with N-terminal fibrillin-1, thereby inhibiting the association of C-terminal latent TGFbeta-binding protein 1 (a component of the large latent complex [LLC]) with N-terminal fibrillin-1. By releasing LLC from microfibrils, the fibrillin-1 sequence encoded by exons 44-49 can contribute to MFS and related diseases.

Substrate chemistry influences the morphology and biological function of adsorbed extracellular matrix assemblies.

In addition to mediating cell signalling events, native extracellular matrix (ECM) assemblies interact with other ECM components, act as reservoirs for soluble signalling molecules and perform structural roles. The potential of native ECM assemblies in the manufacture of biomimetic materials has not been fully exploited due, in part, to the effects of substrate interactions on their morphology. We have previously demonstrated that the ECM components, fibrillin and type VI collagen microfibrils, exhibit substrate dependent morphologies on chemically and topographically variable heterogeneous surfaces. Using both cleaning and coating approaches on silicon wafers and glass coverslips we have produced chemically homogeneous, topographically similar substrates which cover a large amphiphilic range. Extremes of substrate amphiphilicity induced morphological changes in periodicity, curvature and lateral spreading which may mask binding sites or disrupt domain structure. Biological functionality, as assayed by the ability to support cell spreading, was significantly reduced for fibrillin microfibrils adsorbed on highly hydrophilic substrates (contact angle 20.7 degrees) compared with less hydrophilic (contact angle 38.3 degrees) and hydrophobic (contact angle 92.8 degrees) substrates. With an appropriate choice of surface chemistry, multifunctional ECM assemblies retain their native morphology and biological functionality.