Murine matrix metalloproteinase 13 and its human homologue are involved in remodelling processes after myocardial infarction

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): German Centre for Cardiovascular Research (DZHK)

Background

Cardiovascular diseases such as myocardial infarction (MI) are a leading cause of death worldwide. Since matrix metalloproteinases (MMPs) are essential for the cleavage of collagen as well as for the modification of inflammatory proteins and cytokines, they play a substantial role in remodelling processes after MI.

Purpose

Previous results of our group revealed, that Mmp13 expression is upregulated post-MI in mice, while it is downregulated after Ischemia/Reperfusion (I/R), indicating an involvement in remodelling processes. In humans, the functional homologue of Mmp13 is MMP1. Single nucleotide polymorphisms (SNPs) in the promotor of MMP1 can lead to alterations in its gene expression level. We analysed the genotype for 3 MMP1 SNPs in a human cohort containing ~2000 patients who presented to the emergency department with suspected MI to identify their associations with development of MI and outcome after MI.

Methods

The Mmp13 expression in different cardiac cell types was investigated at quiescent stage and under ischaemic conditions, to determine the cellular origin of Mmp13 expression. A MMP13-knockout (KO) mouse model was examined after induction of MI or I/R. Thus, gene expression analysis, histological staining and hemodynamic measurements were conducted to analyse differences between KO and WT as well as between MI and I/R. Out of the human cohort, 2 patient groups (non-MI and MI) were restricted, and Hazard ratios were calculated to evaluate risk for MI and risk for death after MI in dependency of the SNPs.

Results

The Mmp13 expression in macrophages (6.6-fold to control; p=0.0286) and fibroblasts (4.9-fold; p=0.0079) increased significantly after activation with ischaemic secretome of cardiomyocytes, while Mmp13 expression of leucocytes was unaltered. After stimulation with ischaemic secretome of fibroblasts, Mmp13 expression in macrophages (4.3-fold; p=0.0286) and leukocytes (2.3-fold; p=0.0260) was significantly elevated as well. Comparing MI and I/R, the immune cell infiltration revealed significant differences 1-day post-intervention. About 50% of WT mice but only few KO mice died (p=0.0107) after MI due to cardiac rupture. Moreover, KO mice showed an improved cardiac function compared to WT mice after MI. Risk for death was significantly altered between the investigated genotypes in 2 of 3 investigated SNPs in the BACC cohort.

Conclusion

Activated macrophages and leucocytes express high levels of Mmp13 in cell culture experiments. The infiltrating immune cell types are different between MI and I/R, which might lead to differences in Mmp13 expression in these models. MMP13 KO mice are protected from cardiac rupture after MI and unveiled improved cardiac function 28 days post-MI. SNPs of the human homologue of Mmp13 – MMP1 – showed an association of MMP1 with remodelling processes after MI.

Tracking emotions and emotion regulation strategies used in a hospital staff cohort during the COVID-19 pandemic

Introduction

In response to collective life events, many people regulate their emotional states through social interactions to reduce cognitive tolls. During pandemics, physical distancing renders the social support strategy less viable, increasing mental health risks.

Objectives

The current work aims to understand the range of emotions and strategies used in a population of Mental Health staff.

Methods

We conducted an anonymous survey on staff from OMH facilities (n=211) to assess the impact of Covid-19. The current survey captures a host of social, affective, and demographic variables. Accompanied by scales on emotions, emotion regulation, risk, and perception.

Results

Work, family, and health-concerns were the primary contributors to mood. The most common strategy was “situation-avoidance,” then “exercising.” When comparing depression scores against whether or not specific kinds of regulation strategies were utilized, only differences in the strategy of “emotion-suppression” and “authority-seeking” were substantially related to the CES-D scores. Specifically, participants who kept feelings to themselves tended to have higher CES-D scores than those who let their feelings show, while those who sought out authority scored lower on the CES-D, on average than those that did not seek authority.

Conclusions

Healthcare staff are under greater stress and pressure during national emergencies, and to regulate emotions during consistent high-stress, our preliminary data suggest that suppression and distraction strategies are dominant. Suggesting that staff prefer or have little choice but to focus on work. Alternatively, perhaps they are overwhelmed to the extent that avoidance and distraction are more accessible strategies. Further analysis of our data may help us understand more.

Influence of sorbitol on protein crowding in solution and freeze-concentrated phases

Small-angle neutron scattering was employed to study protein crowding under freezing conditions that mimic those used in pharmaceutical processing. The results demonstrate that, although there is an increase in heterogeneity as the temperature is reduced, sorbitol reduces protein crowding in both solution and freeze-concentrated phases, thus protecting the protein from forming oligomers or irreversible aggregates.

Phase-sensitive small-angle neutron scattering

A method is described for determining the neutron scattering length density distribution of a molecular-scale object directly from phase-sensitive small-angle neutron scattering (SANS). The structure factor amplitude is obtained through the use of a reference structure for a collection of randomly oriented, identical objects in the dilute solution limit (negligible interparticle correlations). This work extends some of the techniques developed in recent years for phase-sensitive specular neutron reflectometry to SANS, although the approach presented here is applicable only within the range of validity of the Born approximation. The scattering object is treated as a composite consisting of an `unknown' part of interest plus a reference component, the real-space structure of the latter being completely known. If, for example, the reference part of the object is composed of a ferromagnetic material (the magnetization of which is saturated), then polarized neutron beams can be employed to extract the information required for an unambiguous inversion of the scattering data without chemical substitution. The angular averaging over all possible relative orientations of the composite object does not result in a cancellation of the phase information since the reference and unknown parts of each object have a fixed spatial relationship. The new approach proposed here is not simply another type of isomorphic substitution, but also involves a reformulation of the underlying mathematical analysis of this particular scattering problem.

Atomistic ensemble modeling and small-angle neutron scattering of intrinsically disordered protein complexes: applied to minichromosome maintenance protein

The minichromosome maintenance (MCM) proteins are thought to function as the replicative helicases in archaea and eukarya. In this work we determined the solution structure of the N-terminal portion of the MCM complex from the archaeon Methanothermobacter thermautotrophicus (N-mtMCM) in the presence and absence of DNA using small-angle neutron scattering (SANS). N-mtMCM is a multimeric protein complex that consists of 12 monomers, each of which contains three distinct domains and two unstructured regions. Using an all-atom approach incorporating modern force field and Monte Carlo methods to allow the unstructured regions of each monomer to be varied independently, we generated an ensemble of biologically relevant structures for the complex. An examination of the subsets of structures that were most consistent with the SANS data revealed that large movements between the three domains of N-mtMCM can occur in solution. Furthermore, changes in the SANS curves upon DNA binding could be correlated to the motion of a particular N-mtMCM domain. These results provide structural support to the previously reported biochemical observations that large domain motions are required for the activation of the MCM helicase in archaea and eukarya. The methods developed here for N-mtMCM solution structure modeling should be suitable for other large protein complexes with unstructured flexible regions.

Toward true 3D visualization of active catheters using compressed sensing

A crucial requirement in MR-guided interventions is the visualization of catheter devices in real time. However, true 3D visualization of the full length of catheters has hitherto been impossible given scan time constraints. Compressed sensing (CS) has recently been proposed as a method to accelerate MR imaging of sparse objects. Images acquired with active interventional devices exhibit a high CNR and are inherently sparse, therefore rendering CS ideally suited for accelerating data acquisition. A framework for true visualization of active catheters in 3D is proposed employing CS to gain high undersampling factors making real-time applications feasible. Constraints are introduced taking into account prior knowledge of catheter geometry and catheter motion over time to improve and accelerate image reconstruction. The potential of the method is demonstrated using computer simulations and phantom experiments and in vivo feasibility is demonstrated in a pig experiment.

Branchless and Hedgehog operate in a positive feedback loop to regulate the initiation of neuroblast division in the Drosophila larval brain

The Drosophila central nervous system is produced by two rounds of neurogenesis: one during embryogenesis to form the larval brain and one during larval stages to form the adult central nervous system. Neurogenesis caused by the activation of neural stem division in the larval brain is essential for the proper patterning and functionality of the adult central nervous system. Initiation of neuroblast proliferation requires signaling by the Fibroblast Growth Factor homolog Branchless and by the Hedgehog growth factor. We show here that the Branchless and Hedgehog pathways form a positive feedback loop to regulate the onset of neuroblast division. This feedback loop is initiated during embryogenesis. Our genetic and molecular studies demonstrate that the absolute level of Branchless and Hedgehog signaling is critical to fully activate stem cell division. Furthermore, over-expression and mutant studies establish that signaling by Branchless is the crucial output of the feedback loop that stimulates neuroblast division and that Branchless signaling is necessary for initiating the division of all mitotically regulated neuroblasts in the brain lobes. These studies establish the molecular mechanism through which Branchless and Hedgehog signaling interface to regulate the activation of neural stem cell division.

Phase IIa trial of cilengitide (EMD121974) single-agent therapy in patients (pts) with recurrent glioblastoma (GBM): EMD 121974-009

2002

Background: Our phase IIa study evaluated the safety, toxicity, and clinical activity of the cyclic RGD pentapeptide cilengitide (EMD121974), an inhibitor of integrins avβ3 and avβ5, as a single agent at doses of 500 and 2000 mg in pts with recurrent GBM. Methods: In this multicenter, open-label, randomized, uncontrolled study, pts with GBM and measurable disease that had relapsed after previous temozolomide and radiotherapy were randomized to receive cilengitide at either 500 mg or 2000 mg i.v., 2x/week, until progression. Neurologic exams were performed after every cycle (4 weeks) and MRIs were performed every other cycle. Central, blinded pathology and radiology reviews were performed. The primary endpoint was Progression Free Survival (PFS) at 6 months (6-mth PFS). Secondary endpoints included response, survival, time to disease progression, safety, tolerability and pharmacokinetics (PK). Results: 81 pts accrued (median Karnofsky Performance Status 80%; median age 57 yrs) at 15 sites including 41 at the 500 mg and 40 at the 2000 mg dose levels. Demographic and pretreatment variables were comparable between dose level cohorts. The median number of infusions was 16 [range, 4–179]. PK studies revealed significantly greater exposures among the 2000 mg cohort. Treatment related NCI CTC grade 3 adverse events (AEs) included elevated transaminases (at 500 mg), arthralgia/ myalgia (at 500 mg), and weight increase/ edema (at 2000 mg) in 1 patient, respectively. No grade 4 therapy related AEs were reported. One CTC grade 2 cerebral hemorrhage was reported in a pt at progression. The 6- mth PFS was 16.1% (n=13/81 pts). 10 pts (12.3 %, n=4 with 500 mg, n=6 with 2000 mg) received 12 or more cycles. Six pts (7.4%) remain progression-free and on treatment. Median Overall Survival (mOS) was 6.5 mths [95% CI: 5.2–9.3 mths] in the 500 mg arm and 9.9 mths [95% CI, 6.3–15.7 mths] in the 2000 mg arm. Although not statistically significant, there was a trend towards better tumor control in pts receiving 2000 mg 2x/week. Conclusions: Cilengitide was well tolerated and demonstrated single agent activity in recurrent GBM, with long term disease stabilization in a subset of pts.

[Table: see text]

Sonographische Diagnostik vergrößerter Lymphknoten

BACKGROUND

The purpose of this study was to categorize enlarged superficial lymph nodes as benign or malignant using sonomorphologic features and vascularization pattern.

PATIENTS AND METHODS

Enlarged superficial lymph nodes in 57 patients were assessed with B-mode and contrast-enhanced power Doppler sonography. Morphology and vascularization were evaluated. The lymph nodes were categorized as benign or malignant. Correlation was made with histology and follow-up results.

RESULTS

In 55 patients, 40 lymph nodes were correctly categorized as benign and 15 lymph nodes correctly as malignant. The most reliable criteria were shape and vascularization pattern. Intact hilar vessels and branching indicated benign enlargement, destruction of the hilum with vessels running peripherally along the capsule indicated metastatic destruction. Two benign lymph nodes were considered malignant (false positive).

CONCLUSION

B-mode ultrasound along with contrast-enhanced power Doppler ultrasound is an easy, cost-effective, and reliable tool for differentiation and categorization of enlarged superficial lymph nodes.

Effect of sulfur availability on the integrity of amino acid biosynthesis in plants

Amino acid levels in plants are regulated by a complex interplay of regulatory circuits at the level of enzyme activities and gene expression. Despite the diversity of precursors involved in amino acid biosynthesis as providing the carbon backbones, the amino groups and, for the amino acids methionine and cysteine, the sulfhydryl group and despite the involvement of amino acids as substrates in various downstream metabolic processes, the plant usually manages to provide relatively constant levels of all amino acids. Here we collate data on how amino acid homeostasis is shifted upon depletion of one of the major biosynthetic constituents, i.e., sulfur. Arabidopsis thaliana seedlings exposed to sulfate starvation respond with a set of adaptation processes to achieve a new balance of amino acid metabolism. First, metabolites containing reduced sulfur (cysteine, glutathione, S-adenosylmethionine) are reduced leading to a number of downstream effects. Second, the relative excess accumulation of N over S triggers processes to dump nitrogen in asparagine, glutamine and further N-rich compounds like ureides. Third, the depletion of glutathione affects the redox and stress response system of the glutathione-ascorbate cycle. Thus, biosynthesis of aromatic compounds is triggered to compensate for this loss, leading to an increased flux and accumulation of aromatic amino acids, especially tryptophan. Despite sulfate starvation, the homeostasis is kept, though shifted to a new state. This adaptation process keeps the plant viable even under an adverse nutritional status.

Genetic basis for increased intestinal permeability in families with Crohn's disease: role of CARD15 3020insC mutation?

BACKGROUND AND AIMS

A genetically impaired intestinal barrier function has long been suspected to be a predisposing factor for Crohn's disease (CD). Recently, mutations of the capsase recruitment domain family, member 15 (CARD15) gene have been identified and associated with CD. We hypothesise that a CARD15 mutation may be associated with an impaired intestinal barrier.

METHODS

We studied 128 patients with quiescent CD, 129 first degree relatives (CD-R), 66 non-related household members (CD-NR), and 96 healthy controls. The three most common CARD15 polymorphisms (R702W, G908R, and 3020insC) were analysed and intestinal permeability was determined by the lactulose/mannitol ratio.

RESULTS

Intestinal permeability was significantly increased in CD and CD-R groups compared with CD-NR and controls. Values above the normal range were seen in 44% of CD and 26% of CD-R but only in 6% of CD-NR, and in none of the controls. A household community with CD patients, representing a common environment, was not associated with increased intestinal permeability in family members. However, 40% of CD first degree relatives carrying a CARD15 3020insC mutation and 75% (3/4) of those CD-R with combined 3020insC and R702W mutations had increased intestinal permeability compared with only 15% of wild-types, indicating a genetic influence on barrier function. R702W and G908R mutations were not associated with high permeability.

CONCLUSIONS

In healthy first degree relatives, high mucosal permeability is associated with the presence of a CARD15 3020insC mutation. This indicates that genetic factors may be involved in impairment of intestinal barrier function in families with IBD.

Close localization of DAP-kinase positive tumour-associated macrophages and apoptotic colorectal cancer cells

The death-associated protein kinase (DAP-kinase) is a cytoskeleton-associated protein crucially involved in the induction of early apoptotic pathways. Aberrant hypermethylation of the DAP-kinase promoter plays a major role in tumorigenesis. We aimed to investigate the inactivation of DAP-kinase and its association with apoptotic cell death in 94 colorectal carcinomas. DAP-kinase promoter hypermethylation and mRNA expression were investigated using methylation-specific PCR and real-time RT-PCR, respectively. The expression of DAP-kinase, Fas, and Fas-ligand (FasL) proteins was studied by immunohistochemistry and immunofluorescence. Apoptosis of tumour cells was investigated using the TUNEL assay. DAP-kinase was expressed in tumour cells and tumour-invading macrophages and was closely associated with high numbers of apoptotic tumour cells. DAP-kinase expression co-localized with FasL overexpression in tumour-associated macrophages, and aberrant promoter hypermethylation was verified in more than 50% of carcinomas. There was a tendency for proximal tumours to show DAP-kinase promoter methylation more frequently (p = 0.07). Promoter methylation resulted in a decrease or loss of DAP-kinase protein expression in tumour cells and tumour-associated macrophages. Simultaneously, a decreased apoptotic count and loss of Fas/FasL expression was observed in tumour cells. Our study is the first to demonstrate DAP-kinase expression in invading tumour-associated macrophages in colorectal cancer. The presence of similar expression levels of DAP-kinase in tumour cells and associated macrophages, and their dependence on the promoter methylation status of the tumour cells, suggests cross talk between these cell types during apoptotic cell death.

Detection of submicron-sized raft-like domains in membranes by small-angle neutron scattering

Using coarse grained models of heterogeneous vesicles we demonstrate the potential for small-angle neutron scattering (SANS) to detect and distinguish between two different categories of lateral segregation: 1) unilamellar vesicles (ULV) containing a single domain and 2) the formation of several small domains or "clusters" (approximately 10 nm in radius) on a ULV. Exploiting the unique sensitivity of neutron scattering to differences between hydrogen and deuterium, we show that the liquid ordered (lo) DPPC-rich phase can be selectively labeled using chain deuterated dipalymitoyl phosphatidylcholine (dDPPC), which greatly facilitates the use of SANS to detect membrane domains. SANS experiments are then performed in order to detect and characterize, on nanometer length scales, lateral heterogeneities, or so-called "rafts", in approximately 30 nm radius low polydispersity ULV made up of ternary mixtures of phospholipids and cholesterol. For 1:1:1 DOPC:DPPC:cholesterol (DDC) ULV we find evidence for the formation of lateral heterogeneities on cooling below 30 degrees C. These heterogeneities do not appear when DOPC is replaced by SOPC. Fits to the experimental data using coarse grained models show that, at room temperature, DDC ULV each exhibit approximately 30 domains with average radii of approximately 10 nm.

Conformational changes in single-strand DNA as a function of temperature by SANS

Small-angle neutron scattering (SANS) measurements were performed on a solution of single-strand DNA, 5'-ATGCTGATGC-3', in sodium phosphate buffer solution at 10 degrees C temperature increments from 25 degrees C to 80 degrees C. Cylindrical, helical, and random coil shape models were fitted to the SANS measurements at each temperature. All the shapes exhibited an expansion in the diameter direction causing a slightly shortened pitch from 25 degrees C to 43 degrees C, an expansion in the pitch direction with a slight decrease in the diameter from 43 degrees C to 53 degrees C, and finally a dramatic increase in the pitch and diameter from 53 degrees C to 80 degrees C. Differential scanning calorimeter scans of the sequence in solution exhibited a reversible two-state transition profile with a transition temperature of 47.5 +/- 0.5 degrees C, the midpoint of the conformational changes observed in the SANS measurements, and a calorimetric transition enthalpy of 60 +/- 3 kJ mol(-1) that indicates a broad transition as is observed in the SANS measurements. A transition temperature of 47 +/- 1 degrees C was also obtained from ultraviolet optical density measurements of strand melting scans of the single-strand DNA. This transition corresponds to unstacking of the bases of the sequence and is responsible for the thermodynamic discrepancy between its binding stability to its complementary sequence determined directly at ambient temperatures and determined from extrapolated values of the melting of the duplex at high temperature.

A coarse graining approach to determine nucleic acid structures from small angle neutron scattering profiles in solution

We present a theoretical method to calculate the small angle neutron scattering profile of nucleic acid structures in solution. Our approach is sensitive to the sequence and the structure of the nucleic acid. In order to test our approach, we apply this method to the calculation of the experimental scattered intensity of the decamer d(CCAACGTTGG)₂ in H₂O. This sequence was specifically chosen for this study as it is believed to adopt a canonical B-form structure in 0.3 M NaCl. We find that not only will our methodology reproduce the experimental scattered intensity for this sequence, but our method will also discriminate between B-, A- and Z-form DNA. By studying the scattering profile of this structure in 0.5 and 1.0 M NaCl, we are also able to identify tetraplex and other similar oligomers formation and to model the complex using the experimental scattering data in conjunction with our methodology.

Effect of baseline or changes in adrenergic activity on clinical outcomes in the beta-blocker evaluation of survival trial

BACKGROUND

Adrenergic activation is thought to be an important determinant of outcome in subjects with chronic heart failure (CHF), but baseline or serial changes in adrenergic activity have not been previously investigated in a large patient sample treated with a powerful antiadrenergic agent.

METHODS AND RESULTS

Systemic venous norepinephrine was measured at baseline, 3 months, and 12 months in the beta-Blocker Evaluation of Survival Trial (BEST), which compared placebo treatment with the beta-blocker/sympatholytic agent bucindolol. Baseline norepinephrine level was associated with a progressive increase in rates of death or death plus CHF hospitalization that was independent of treatment group. On multivariate analysis, baseline norepinephrine was also a highly significant (P<0.001) independent predictor of death. In contrast, the relation of the change in norepinephrine at 3 months to subsequent clinical outcomes was complex and treatment group-dependent. In the placebo-treated group but not in the bucindolol-treated group, marked norepinephrine increase at 3 months was associated with increased subsequent risks of death or death plus CHF hospitalization. In the bucindolol-treated group but not in the placebo-treated group, the 1st quartile of marked norepinephrine reduction was associated with an increased mortality risk. A likelihood-based method indicated that 18% of the bucindolol group but only 1% of the placebo group were at an increased risk for death related to marked reduction in norepinephrine at 3 months.

CONCLUSIONS

In BEST, a subset of patients treated with bucindolol had an increased risk of death as the result of sympatholysis, which compromised the efficacy of this third-generation beta-blocker.

Secretory heat-shock protein as a dendritic cell-targeting molecule: a new strategy to enhance the potency of genetic vaccines

DNA vaccines are an appealing strategy for inducing cytotoxic T-lymphocyte and antibody responses against tumor cells as well as infectious agents. Dendritic cells (DCs) play a critical role in inducing immune responses, but their potential is not fully utilized in the DNA vaccine setting since they take up only a minor fraction of the injected DNA. Here we describe a novel DNA vaccination strategy based on the targeting of a modified tumor-associated antigen, the human papilloma virus (HPV) type 16 E7 protein, to DCs by a heat-shock protein (HSP) to enhance antigen presentation and immune responses. Specifically, a chimerical HPV-E7 and HSP70 fusion gene preceded with a leader sequence was constructed. When mice were immunized with this construct, the DNA is taken up by various types of cells, which then produce and secrete an HPV-E7-HSP70 fusion protein that is targeted to DCs by the HSP70 portion of the chimerical molecule for antigen presentation. In studies to test the efficacy of this strategy, we demonstrated that DNA vaccination with this secretory HPV-E7-HSP70 construct strongly enhanced an antigen-specific CD8+ T-cell response as well as a specific B-cell response in mice. Furthermore, this immunization approach not only protected mice against lethal challenge with an HPV E7-expressing tumor line (TC-1), but also showed a therapeutic effect against established tumors. The results of this study indicate that secretory HSPs can be broadly used to target tumor-associated antigens to DCs to enhance antigen-specific immune responses.

Simplified microvascular suture techniques for rat liver transplantation as a microsurgical model with arterial blood supply

The methods for liver transplantation in the rat mainly used do not include reconstruction of the arterial blood supply to the liver. Furthermore, to ensure a short anhepatic phase these methods almost all entail specially developed cuff anastomoses in the recipient operation instead of the conventional microvascular suture technique. Thus an acceptable survival rate can be attained in the experimental animals. This detailed description of simplified microvascular suture techniques is intended to present an alternative to the cuff anastomoses used almost exclusively. In the donor operation with this method, the liver is dissected with an arterial pedicle including the abdominal segment of the aorta, and the liver is flushed in situ not only via the portal vein, but also via the hepatic artery. The organ is implanted in the recipient animal using simplified microvascular suture reconstruction of the arterial blood supply to the liver. Use of telescopic spectacles with 2-fold magnification has proven to be adequate for the entire procedure. With mastery of this method of rat liver transplantation, the average duration of the anhepatic phase is about 20 min, substantially below the 30-min limit which is critical for the survival of the experimental animals. The donor operation requires about 60 min, and the recipient operation 70 to 80 min. With this method, the spectrum of investigations on liver transplantation which are possible in the rat is substantially extended in that clinical conditions can be reproduced very much more exactly by combination of portal and arterial in-situ flushing in the donor operation and rearterialization of the transplant in the recipient operation, as compared to the transplanted rat liver being supplied only with portal venous blood.

Acetylsalicylic acid and microembolic events detected by transcranial Doppler in symptomatic arterial stenoses

BACKGROUND

In patients with symptomatic carotid artery stenosis, high-intensity transient signals detected by transcranial Doppler (TCD) have been related to particulate microemboli originating at the stenotic lesion. The occurrence of these microembolic events within the Doppler spectrum should be influenced by antithrombotic agents of proven efficacy in these patients mainly by reducing cerebral embolism.

METHODS

Seventy-four of 192 consecutive patients with symptomatic arterial stenosis in the anterior circulation and clinical symptoms within the last 30 days underwent 1-hour bilateral TCD monitoring. Patients were selected, if they presented temporal bone windows enabling transcranial insonation, revealed normal Doppler CO2 test excluding hemodynamic impairment, had not received antithrombotic therapy other than acetylsalicylic acid (ASA) before sonographic examination, and gave informed consent to 1-hour monitoring which could be performed immediately on admission/presentation of the patient at the Department of Neurology.

RESULTS

Microembolic events were detected in 38 patients (51%). The proportion of patients with events among 26 patients without antithrombotic medication was 73% as compared with 40% in 48 patients receiving ASA at the time of TCD monitoring (p = 0.023). Multivariate analysis including time from ischemia to TCD, presence and start of ASA prevention, degree and localization of stenosis, and presence of a single or recurrent ischemia revealed that absence of an ASA prevention (odds ratio OR 7.1, 95% confidence interval CI 1.6-31.4, p = 0.010), recurrent ischemic events (OR 7.1, 95% CI 1.6-32.7, p = 0.011), and extracranial localization of the stenosis (OR 3.8, 95% CI 1.1-13.2, p = 0.038) were independent predictors for microembolic events.

CONCLUSION

In patients with symptomatic arterial stenosis, the absence of an ASA medication is associated with the occurrence of TCD-detected microembolic events, suggesting a relation between these events and ASA-sensitive microemboli from the stenotic lesion.

Cessation of embolic signals after antithrombotic prevention is related to reduced risk of recurrent arterioembolic transient ischaemic attack and stroke

OBJECTIVES

To evaluate the reduction of embolic signals after the initiation of an antithrombotic secondary prevention in patients with recent arterioembolic stroke and to determine the predictive value of decreased microembolism on the risk of early stroke recurrence.

METHODS

Eighty six consecutive patients (55 men, 31 women; mean age 60.6 years) with a non-disabling arterioembolic ischaemic event in the anterior circulation within the last 30 days and a medium grade or high grade stenosis (> or =50%) of the ipsilateral carotid or middle cerebral artery underwent 1 hour transcranial Doppler monitoring as part of the admission examinations. Antithrombotic secondary prevention was started after completion of admission. Patients in whom embolic signals were detected underwent a second monitoring within 4 days (mean time 1.8 days). All patients were followed up prospectively to evaluate the relation between presence and persistence of embolic signals and the risk of recurrent transient ischaemic attack (TIA) and stroke within the next 6 weeks.

RESULTS

In 44 patients, embolic signals were detected at admission, a mean 5.4 days (range 0 to 21 days) after the initial event. Twenty five were positive for embolic signals also at the second monitoring, in 19 signals had ceased. Forty two patients without embolic signals at admission served as controls. During follow up, six ischaemic events (two stroke, three TIA, one amaurosis fugax) occurred in 25 patients with persisting embolic signals but none in 19 patients in whom signals had ceased by the second monitoring. One patient in the control group had a TIA. The incidence of a recurrent event was 0.45 per 30 patient-days if embolic signals persisted compared with 0.015 if signals could not be detected or had ceased. Persistence of embolic signals was an independent predictor of a recurrent TIA or stroke (adjusted odds ratio 37.0; 95% confidence interval (95% CI) 3.5 to 333; p<0.003). Cessation and decrease of embolic signals was associated with the administration of antiplatelet agents but not with anticoagulation with intravenous heparin (p<0.001).

CONCLUSIONS

Rapid cessation of embolic signals detected in patients with recently symptomatic arterial stenosis decreases increased risk of an early ischaemic recurrence. Effect of antithrombotic agents on embolic signals might serve as a marker for their efficacy on preventing stroke recurrence.

Morphology of fast-tumbling bicelles: a small angle neutron scattering and NMR study

Bilayered micelles, or bicelles, which consist of a mixture of long- and short-chain phospholipids, are a popular model membrane system. Depending on composition, concentration, and temperature, bicelle mixtures may adopt an isotropic phase or form an aligned phase in magnetic fields. Well-resolved (1)H NMR spectra are observed in the isotropic or so-called fast-tumbling bicelle phase, over the range of temperatures investigated (10-40 degrees C), for molar ratios of long-chain lipid to short-chain lipid between 0.20 and 1.0. Small angle neutron scattering data of this phase are consistent with the model in which bicelles were proposed to be disk-shaped. The experimentally determined dimensions are roughly consistent with the predictions of R.R. Vold and R.S. Prosser (J. Magn. Reson. B 113 (1996)). Differential paramagnetic shifts of head group resonances of dimyristoylphosphatidylcholine (DMPC) and dihexanoylphosphatidylcholine (DHPC), induced by the addition of Eu(3+), are also consistent with the bicelle model in which DHPC is believed to be primarily sequestered to bicelle rims. Selective irradiation of the DHPC aliphatic methyl resonances results in no detectable magnetization transfer to the corresponding DMPC methyl resonances (and vice versa) in bicelles, which also suggests that DHPC and DMPC are largely sequestered in the bicelle. Finally, (1)H spectra of the antibacterial peptide indolicidin (ILPWKWPWWPWRR-NH(2)) are compared, in a DPC micellar phase and the above fast-tumbling bicellar phases for a variety of compositions. The spectra exhibit adequate resolution and improved dispersion of amide and aromatic resonances in certain bicelle mixtures.

Cathepsin L antisense oligonucleotides in a human osteosarcoma cell line: effects on the invasive phenotype

Alterations in cathepsin L expression and trafficking have been associated with the progression and metastasis of several tumor entities. In the present study, we examined the effects of various cathepsin L antisense (as) phosphorothioate oligonucleotides on both the expression of cathepsin L and the invasive potential of the human osteosarcoma cell line MNNG/HOS. Seven oligonucleotides of 20-bp length each and one random control oligonucleotide were chosen to block cathepsin L expression. Northern blot analysis demonstrated a significant reduction in cathepsin L mRNA expression by the six antisense oligonucleotides at a concentration of 10 microM. Cathepsin L protein expression was reduced significantly (50-85%) by the antisense oligonucleotides, as compared with the controls. Adhesion to matrices of collagen I and matrigel was not affected. In in vitro motility and invasion assays performed in uncoated and precoated transwell chambers, the ability of cells to migrate through the filters was inhibited by 35-75% using antisense oligonucleotides. The random control did not show any inhibitory effect. These data demonstrate that in MNNG/HOS cells cathepsin L influences cellular malignancy by promoting migration and basement membrane degradation.

Hydration state of single cytochrome c monolayers on soft interfaces via neutron interferometry

Yeast cytochrome c (YCC) can be covalently tethered to, and thereby vectorially oriented on, the soft surface of a mixed endgroup (e.g., -CH3/-SH = 6:1, or -OH/-SH = 6:1) organic self-assembled monolayer (SAM) chemisorbed on the surface of a silicon substrate utilizing a disulfide linkage between its unique surface cysteine residue and a thiol endgroup. Neutron reflectivities from such monolayers of YCC on Fe/Si or Fe/Au/Si multilayer substrates with H2O versus D2O hydrating the protein monolayer at 88% relative humidity for the nonpolar SAM (-CH3/-SH = 6:1 mixed endgroups) surface and 81% for the uncharged-polar SAM (-OH/-SH = 6:1mixed endgroups) surface were collected on the NG1 reflectometer at NIST. These data were analyzed using a new interferometric phasing method employing the neutron scattering contrast between the Si and Fe layers in a single reference multilayer structure and a constrained refinement approach utilizing the finite extent of the gradient of the profile structures for the systems. This provided the water distribution profiles for the two tethered protein monolayers consistent with their electron density profile determined previously via x-ray interferometry (Chupa et al., 1994).

Possible contribution of aminopeptidase N (APN/CD13) to invasive potential enhanced by interleukin-6 and soluble interleukin-6 receptor in human osteosarcoma cell lines

This study aimed at clarifying the role of Aminopeptidase N (APN), a Zn2+-dependent ectopeptidase localized on the cell surface of human osteosarcoma cell lines treated with proinflammatory cytokines. We investigated the proinflammatory cytokines interleukin-1 beta (IL-1beta), IL-6 and tumor necrosis factor alpha (TNF-alpha) as well as the anti-inflammatory cytokine transforming growth factor beta (TGF-beta) for their influence on APN regulation. Soluble IL-6 receptor (sIL-6R) was always used together with IL-6 to achieve a stable effect. In addition, the invasive potential of the osteosarcoma cell lines MG63 and HOS was examined. Competitive RT-PCR and Ala-pNA activity assays revealed that IL-6 and sIL-6R significantly increased the mRNA expression and activity of APN in both osteosarcoma cell lines. Although IL-1beta significantly stimulated APN mRNA expression in both cell lines, it influenced the enzyme activity only in MG63. TNF-alpha and TGF-beta, however, had an effect neither on mRNA expression nor on the enzyme activity of APN in both cell lines. In the Matrigel invasion assay, IL-6 and sIL-6R significantly up-regulated the transmigration of these cell lines, whereas other cytokines did not. The up-regulated invasion was inhibited by bestatin, a specific inhibitor of APN. Cellular migration correlated highly with APN activity (r = 0.79, P < 0.002). These findings suggest that APN contributes to the invasive potential of human osteosarcomas enhanced by IL-6 and SIL-6R.

Regulatory responses to an oral D-glutamate load: formation of D-pyrrolidone carboxylic acid in humans

Previously published studies have shown D-glutamate to be the most potent natural inhibitor of glutathione synthesis known, yet how D-glutamate is handled in humans is unknown. Therefore, we administered an oral D-glutamate load to four healthy volunteers and monitored the plasma D-glutamate concentration and excretion over a 3-h postload period. Compared with time controls, the plasma D-glutamate concentration increased 10-fold in the 1st h and then reached a plateau over the remaining time course. In contrast, plasma D-pyrrolidone carboxylic acid increased progressively throughout the 3-h time course to a level 10-fold higher than the D-glutamate plasma concentration. Excretion of D-glutamate progressively increased despite a constant filtered D-glutamate load rising from only 5 to 95% of the filtered amount. Excretion of D-pyrrolidone carboxylic acid increased with the rise in filtered load without significant reabsorption. The amount of D-pyrrolidone carboxylic acid excreted over the 3-h time course was 10 times the amount excreted as D-glutamate and accounted for almost 20% of the administered D-glutamate. These findings indicate that plasma D-glutamate concentration is tightly regulated through two mechanisms: 1) the transport into cells and metabolic conversion to D-pyrrolidone carboxylic acid and excretion, and 2) the enhancement of D-glutamate clearance by the kidneys.

Materials Research With Neutrons at NIST

The NIST Materials Science and Engineering Laboratory works with industry, standards bodies, universities, and other government laboratories to improve the nation's measurements and standards infrastructure for materials. An increasingly important component of this effort is carried out at the NIST Center for Neutron Research (NCNR), at present the most productive center of its kind in the United States. This article gives a brief historical account of the growth and activities of the Center with examples of its work in major materials research areas and describes the key role the Center can expect to play in future developments.

First-principles determination of hybrid bilayer membrane structure by phase-sensitive neutron reflectometry

The application of a new, phase-sensitive neutron reflectometry method to reveal the compositional depth profiles of biomimetic membranes is reported. Determination of the complex reflection amplitude allows the related scattering length density (SLD) profile to be obtained by a first-principles inversion without the need for fitting or adjustable parameters. The SLD profile so obtained is unique for most membranes and can therefore be directly compared with the SLD profile corresponding to the chemical compositional profile of the film, as predicted, for example, by a molecular dynamics simulation. Knowledge of the real part of the reflection amplitude, in addition to enabling the inversion, makes it possible to assign a spatial resolution to the profile for a given range of wavevector transfer over which the reflectivity data are collected. Furthermore, the imaginary part of the reflection amplitude can be used as a sensitive diagnostic tool for recognizing the existence of certain in-plane inhomogeneities in the sample. Measurements demonstrating the practical realization of this phase-sensitive technique were performed on a hybrid bilayer membrane (self-assembled monolayer of thiahexa (ethylene oxide) alkane on gold and a phospholipid layer) in intimate contact with an aqueous reservoir. Analysis of the experimental results shows that accurate compositional depth profiles can now be obtained with a spatial resolution in the subnanometer range, primarily limited by the background originating from the reservoir and the roughness of the film's supporting substrate.

Overexpression of cathepsin B and urokinase plasminogen activator is associated with increased risk of recurrence and metastasis in patients with chondrosarcoma

BACKGROUND

Deregulation of the cellular protease network has been shown to be responsible for aggressive clinical behavior in several common human malignancies. In the current study, the authors evaluated the expression patterns of proteases in patients with chondrosarcoma of bone and correlated these patterns with clinical outcome.

METHODS

The expression levels of urokinase plasminogen activator; matrix metalloproteinase types-1, -2, and -9; and cathepsins B and L were determined immunohistochemically in 114 cases of chondrosarcomas of bone and were correlated with their clinicopathologic parameters as well as with long term follow-up data.

RESULTS

Overexpression of cathepsin B was associated with a high rate of local recurrence (P = 0.006) and a decreased recurrence free survival (P = 0.005). Overexpression of urokinase plasminogen activator was associated with an increased rate of metastasis (P = 0. 013), a decreased metastasis free survival (P = 0.016), and a decreased 5-year overall survival rate (P = 0.048). The univariate Cox model showed that tumor extension into soft tissue, high histologic grade, and overexpression of cathepsin B were predictors of adverse outcome. Multivariate analysis showed only overexpression of cathepsin B and tumor extension into soft tissue to be independent predictors of local recurrence.

CONCLUSIONS

Overexpression of cathepsin B and urokinase plasminogen activator can be used to identify those patients with chondrosarcoma of bone who have an increased risk of local recurrence and distant metastases.

Expression of cathepsin K in chordoma

Invasive growth of chordoma is accompanied by severe destruction of adjacent bone tissue, a fact that requires high proteolytic activity at the tumor invasion fronts. In this context, cathepsin K is a candidate molecule. It is a protease with high collagenolytic and elastinolytic activity and previously thought to be restricted to osteoclasts and osteoclast-mediated bone resorption. In this study, 44 cases of chordoma of sphenooccipital localization, and 10 embryo-fetal specimens including chorda dorsalis were studied immunohistochemically for their expression of cathepsin K. In 4 additional snap-frozen chordoma cases, the enzyme expression was investigated by reverse transcription polymerase chain reaction and enzyme histochemistry. Ten chondrosarcomas of the skull base served as controls. Various concentrations of cathepsin K mRNA could be seen in all snap-frozen chordoma specimens. The protease was immunohistochemically expressed by the tumor cells. The immunoreactions were accentuated at the tumor invasion fronts. Enzyme histochemistry indicated a strong tumor cell-associated cathepsin K activity in invasive tumor components. In contrast to chordoma, cathepsin K was not significantly expressed in chorda dorsalis and chondrosarcoma of the skull base. In chondrosarcoma, protease expression was limited to osteoclastic cells localized between infiltrative tumor components and regular bone trabeculae. This study shows the significant expression and activity of cathepsin K in chordoma and implicates an important and direct role of this protease in the infiltrative growth of this tumor. This protease expression occurred during neoplastic transformation and did not appear in chorda dorsalis.

EST comparison indicates 38% of human mRNAs contain possible alternative splice forms

Expressed sequence tag (EST) databases represent a large volume of information on expressed genes including tissue type, expression profile and exon structure. In this study we create an extensive data set of human alternative splicing. We report the analysis of 7867 non-redundant mRNAs, 3011 of which contained alternative splice forms (38% of all mRNAs analysed). From a total of 12572 ESTs 4560 different possible alternative splice forms were detected. Interestingly, 70% of the alternative splice forms correspond to exon deletion events with only 30% exonic insertions. We experimentally verified 19 different splice forms from 16 genes in a total subset of 20 studied; all of the respective genes are of medical relevance.

Interleukin-8 stimulates placental prostacyclin production in preeclampsia

PROBLEM

Our purpose was to determine placental interleukin (IL)-8 production and its correlation with the prostacyclin production in normal and preeclamptic pregnancies and to evaluate the beneficial effect of IL-8 on prostacyclin production.

METHOD OF STUDY

We determined 1) the in vitro production of IL-8 and prostacyclin by placental villous tissues from normal and preeclamptic pregnancies and 2) the production of prostacyclin by villous tissues from preeclampsia treated with recombinant human IL-8 (rhIL-8). IL-8 levels were measured by enzyme-linked immunosorbent assay and prostacyclin by radioimmunoassay of 6-keto PGF1alpha, the stable metabolite of prostacyclin.

RESULTS

1) Placental production of IL-8 and 6-keto PGF1alpha were significantly less in preeclampsia than in normal pregnancies, P<0.05. 2) Placental production of 6-keto PGF1alpha and IL-8 was significantly correlated in preeclampsia, P<0.01. 3) Placental tissues treated with IL-8 exhibited a concentration-dependent increase in 6-keto PGF1alpha production.

CONCLUSIONS

Placental tissues from preeclampsia produce significantly less IL-8 than tissues from normal pregnancies, which correlates with decreased prostacyclin production. IL-8 improves placental prostacyclin production in preeclampsia.