Cardioprotective effect of empagliflozin in acute myocardial infarction: the role of ketone bodies availability

Background

The cardio-renal benefits of SGLT2i have been clearly established by clinical trials. Of interest, despite not having any effect on the incidence of classic atherothrombotic events (MI and strokes), patients receiving SGLT2i treatment had a higher chance of surviving myocardial infarction (MI).

Purpose

We aim to evaluate the cardioprotective potential of empagliflozin on acute myocardial infarction.

We postulate that the benefits of SGLT2-I are mediated via an increase in circulating ketone bodies (KBs) induced by SGLT2i, and its preferential myocardial utilization energetically benefits the heart to better withstand an ischemic event.

Methods

The study was undertaken in our non-diabetic porcine model of ischemia/reperfusion. Animals were allocated to either one-week pre-treatment with empagliflozin or placebo before MI-induction. A third group received IV infusion of KBs at the time of the MI- induction to serve as positive-control. The acute effects of the treatments were studied 24 hours after MI-induction by Cardiac Magnetic Resonance (CMR). Immediately post-CMR, animals were sacrificed and heart samples collected for molecular analysis.

Results

(see Table and Figure): Despite similar initial ischemic injury (area at risk) in all groups, empagliflozin was associated with a significantly higher myocardial salvage (MSI 23.7±9.7 vs 4.5±3.6%, p<0.001) and better preserved cardiac function (LVEF 41.3±3.1 vs 33±5.5%, p<0.009) compared with placebo. The infusion of KBs replicated in part the beneficial profile of the empagliflozin group (MSI 16.7±8.8 and LVEF 39.1±3.6%). Histological analysis showed less cardiomyocyte apoptosis and less oxidative stress

Conclusions

To the best of our knowledge, this is the first study evaluating in vivo the cardioprotective potential of a SGLT2 inhibitor in a well-stablished porcine translational model. Furthermore, effects are evaluated using the gold standard for visualization and quantification of MI, Cardiac Magnetic Resonance (CMR). Three are the main conclusions:

1. One-week treatment with empagliflozin raises circulating KBs levels and confers significant cardio-protection during a myocardial infarction. Acute post-MI benefits (greater myocardial salvage and better preserved cardiac function) are already seen within 24 hours as compared with placebo.

2. Periprocedural IV infusion of KBs induces similar benefits than the SGLT2-I group.

3. These observations strongly support our hypothesis that SGLT2 inhibition is associated with increased circulating KBs and its selective use as preferential myocardial source of energy as a potential mechanism of action involved in the cardio-renal benefits observed with SGLT2i.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): Spanish Society of Cardiology. Research Fellowship Grant.

[Performance-related middle management in medical teaching. Attractiveness of incentive tools from the perspective of the teachers]

BACKGROUND AND OBJECTIVE

German medical schools are increasingly challenged by the competition for public funds and talented students. Therefore. many curriculum planners, deans and school administrators plan to implement a systematic and comprehensive awarding system for good teaching. The OBJECTIVE of this study was to elaborate which specific incentives would be most effective to increase the motivation and enthusiasm for teaching among basic scientists as well as residents and attendings involved in medical education. In addition, a cost-effective model should be developed, which could be used as an adjustable blue-print for an awarding system.

METHODS

Based on literature search, existing approaches to rewards and incentives for medical teachers were analysed by an interdisciplinary committee in coordination with the members' department heads. According to german teaching methods and available resources, a catalogue of specific incentives has been designed and ranked by a representative sample of 200 medical teachers / faculty at two universities. Thus, a variety of favourite rewarding instruments could be elaborated, which were preferred by teachers in theoretical versus clinical disciplines.

RESULTS

The majority of the medical teachers prefer heterogeneously monetary incentives and additional protected time, followed by career-effective incentives (tenure & promotion). The discussion reflects on a transferable catalogue of different rewarding instruments, including a cost-/benefit-analysis and prerequisite students' evaluation data.

CONCLUSION

A single alteration of departmental teaching budgets does not seem to be sufficient. It seems rather advisable, also to strive for a variety of different incentives on a level that predominantly affects individual teaching personnel. Even with comparatively small amounts of money, significant effects on teachers' motivation can be achieved.

Comparison of the chondrosarcoma cell line SW1353 with primary human adult articular chondrocytes with regard to their gene expression profile and reactivity to IL-1beta

OBJECTIVE

In this study, the human chondrosarcoma cell line SW1353 was investigated by gene expression analysis in order to validate it as an in vitro model for primary human (adult articular) chondrocytes (PHCs).

METHODS

PHCs and SW1353 cells were cultured as high density monolayer cultures with and without 1ng/ml interleukin-1beta (IL-1beta). RNA was isolated and assayed using a custom-made oligonucleotide microarray representing 312 chondrocyte-relevant genes. The expression levels of selected genes were confirmed by real-time polymerase chain reaction and the gene expression profiles of the two cell types, both with and without IL-1beta treatment, were compared.

RESULTS

Overall, gene expression profiling showed only very limited similarities between SW1353 cells and PHCs at the transcriptional level. Similarities were predominantly seen with respect to catabolic effects after IL-1beta treatment. In both cell systems matrix metalloproteinase-1 (MMP-1), MMP-3 and MMP-13 were strongly induced by IL-1beta, without significant induction of MMP-2. IL-6 was also found to be up-regulated by IL-1beta in both cellular models. On the other hand, intercellular mediators such as leukemia inhibitory factor (LIF) and bone morphogenetic protein-2 (BMP-2) were not induced by IL-1beta in SW1353 cells, but significantly up-regulated in PHCs. Bioinformatical analysis identified nuclear factor kappa-B (NFkappaB) as a common transcriptional regulator of IL-1beta induced genes in both SW1353 cells and PHCs, whereas other transcription factors were only found to be relevant for individual cell systems.

CONCLUSION

Our data characterize SW1353 cells as a cell line with only a very limited potential to mimic PHCs, though SW1353 cells can be of value to study the induction of protease expression within cells, a phenomenon also seen in chondrocytes.

The TRAPIST Study. A multicentre randomized placebo controlled clinical trial of trapidil for prevention of restenosis after coronary stenting, measured by 3-D intravascular ultrasound

BACKGROUND

Studies have reported benefit of oral therapy with the phosphodiesterase inhibitor, trapidil, in reducing restenosis after coronary angioplasty. Coronary stenting is associated with improved late outcome compared with balloon angioplasty, but significant neointimal hyperplasia still occurs in a considerable proportion of patients. The aim of this study was to investigate the safety and efficacy of trapidil 200 mg in preventing in-stent restenosis.

METHODS

Patients with a single native coronary lesion requiring revascularization were randomized to placebo or trapidil at least 1 h before, and continuing for 6 months after, successful implantation of a coronary Wallstent. The primary end-point was in-stent neointimal volume measured by three-dimensional reconstruction of intravascular ultrasound images recorded at the 6 month follow-up catheterization.

RESULTS

Of 312 patients randomized at 21 centres in nine countries, 303 (148 trapidil, 155 placebo) underwent successful Wallstent implantation, and 139 patients (90%) in the placebo group and 130 (88%) in the trapidil group had repeat catheterization at 26+/-2 weeks. There was no significant difference between trapidil and placebo-treated patients regarding in-stent neointimal volume (108.6+/- 95.6 mm(3)vs 93.3+/-79.1 mm(3);P=0.16) or % obstruction volume (38+/-18% vs 36+/-21%;P=0.32), in angiographic minimal luminal diameter at follow-up (1.63+/-0.61 mm vs 1.74+/-0.69 mm;P=0.17), restenosis rate (31% vs 24%;P=0.24), cumulative incidence of major adverse cardiac events at 7 months (22% vs 20%;P=0.71) or anginal complaints (30% vs 24%;P=0.29).

CONCLUSION

Oral trapidil 600 mg daily for 6 months did not reduce in-stent hyperplasia or improve clinical outcome after successful Wallstent implantation and is not indicated for this purpose.

The influence of stent length on clinical and angiographic outcome in patients undergoing elective stenting for native coronary artery lesions; final results of the Magic 5L Study

AIMS

To prospectively evaluate the influence of stent length on 6 month clinical and angiographic outcome, in patients with native coronary lesions up to 45 mm in length, undergoing elective Magic Wallstent implantation.

METHODS AND RESULTS

On the basis of pre-procedural angiography, 276 patients (aged 61.3+/-10.2 years; 78.6% male; 41.7% unstable angina) with a total of 302 lesions were prospectively assigned to one of five different length categories of Magic Wallstent. Angiography in multiple matched projections before and after implantation and at 6 months follow-up was analysed at the core laboratory. Primary end-points for the efficacy analysis were cumulative incidence of major adverse cardiac events and quantitative coronary angiography analysis 6 months after stent implantation. Magic Wallstent implantation was successful in 301 of 302 lesions and in 98.6% a residual stenosis <20% by online quantitative coronary angiography was achieved. At 30 days, 6.2% (1.8% subacute occlusion) of patients had experienced major adverse cardiac events, 27.5% at 6 months and 30.4% at 9 months. Angiographic restenosis occurred in 37%. Restenosis rates for the mini, extra-short, short, medium and long Wallstent groups were 25.9%, 25%, 22.6%, 36.2% and 67.5%, respectively. Multivariate analysis revealed stent length to be independently associated with greater angiographic restenosis and major adverse cardiac events.

CONCLUSIONS

While shorter Magic Wallstents provided late outcomes comparable with short balloon-expandable stents, excessive restenosis with longer Wallstents should obviate their use in elective percutaneous intervention. Long coronary lesions provide a challenging substrate for emerging antirestenosis therapies, such as stent coatings and brachytherapy.

In vivo pharmacology of BIIR 561 CL, a novel combined antagonist of AMPA receptors and voltage-dependent Na(+) channels

Glutamate receptors of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) subtype and voltage-gated Na(+) channels are associated with diseases of the central nervous system characterized by neuronal over-excitation as in epilepsy or cerebral ischaemia. In animal models, AMPA receptor antagonists and Na(+) channel blockers provide protection in these conditions. Dimethyl-[2-[2-(3-phenyl-[1,2,4]oxadiazol-5-yl)-phenoxyl]-ethyl]-amine hydrochloride (BIIR 561 CL) combines both, AMPA receptor - and Na(+) channel blocking properties in one molecule. Here, BIIR 561 CL was investigated in vivo. BIIR 561 CL protected mice against AMPA-induced toxicity with an ED(50) value of 4.5 mg kg(-1) following subcutaneous (s.c.) administration. A 0.1% solution of BIIR 561 CL provided local anaesthesia in the corneal reflex test in rabbits. In mice, the compound prevented tonic seizures in the maximal electroshock (MES) model with an ED(50) value of 3.0 mg kg(-1) s.c. In amygdala-kindled rats, BIIR 561 CL inhibited seizures at doses of 3 and 11 mg kg(-1) following intraperitoneal (i.p.) injection. The data show that the combination of blocking AMPA receptor- and voltage-gated Na(+) channels in one molecule induces effective protection in animal models of neuronal over-excitation.

Requirement of heat shock protein 90 in mesangial cell mitogenesis

BACKGROUND

Hyperplasia of mesangial cells (MCs) is a frequent finding in glomerulonephritis. Heat shock protein 90 (HSP90) is a major cellular chaperone that assists protein folding under physiological and stress conditions.

METHODS

To identify genes that are potentially involved in the pathogenesis of glomerulonephritis, we analyzed glomerular gene expression in mesangioproliferative rat anti-Thy1.1 nephritis by representational difference analysis (RDA). Expression of HSP90beta in anti-Thy1.1 nephritis was studied by Northern and Western blot analyses and immunohistochemistry. In cultured rat MCs, the requirement of HSP90 for mitogenic signaling steps and MC replication was studied by incubation with the specific HSP90 inhibitor geldanamycin.

RESULTS

By RDA, a cDNA fragment homologous to HSP90beta was identified. Glomerular mRNA and protein expression of HSP90beta was markedly and transiently up-regulated during the course of anti-Thy1.1 nephritis, with a maximum at day 6, coinciding with the peak of MC proliferation. By immunohistochemistry, HSP90beta expression in normal glomeruli was detected in podocytes. However, in anti-Thy1.1 nephritis, glomerular HSP90beta protein expression was strongly and transiently increased in mesangial localization. In vitro, mitogenic stimulation of rat MCs led to the induction of HSP90beta mRNA and protein. Incubation of MCs with geldanamycin dose-dependently inhibited DNA synthesis and replication. Moreover, geldanamycin interfered with mitogen-induced phosphorylation of extracellular signal-regulated kinase and transcription of c-fos and Egr-1, but not with transactivation of STAT1 transcription factor. Cell cycle analysis of serum-stimulated MCs revealed that geldanamycin inhibited kinase activity of cyclin D1/CDK4 complexes and blocked progression in the G0/G1 phase and at the S/G2 phase transition.

CONCLUSIONS

The up-regulation of HSP90beta in anti-Thy1.1 nephritis may reflect its functional involvement in phenotypical alterations of MCs in mesangioproliferative glomerulonephritis. Our in vitro studies indicate that HSP90 governs the capacity of MCs to respond to proliferative stimuli by regulating critical mitogenic signaling steps necessary for G1 entry and S-phase progression.

Multicenter evaluation of the phosphorylcholine-coated biodivYsio stent in short de novo coronary lesions: The SOPHOS study

AIMS: The BiodivYsio trade mark stent (Biocompatibles Ltd, Farnham, UK) is coated with a phosphorylcholine (PC)-containing copolymer to confer biocompatibility. The SOPHOS (Study Of PHosphorylcholine coating On Stents) study was designed to assess the safety and efficacy of this novel coronary stent and by indirect comparison to indicate equivalence with other formal stent studies. METHODS AND RESULTS: Patients with angina and a single short (#x2A7F;12 mm) de novo lesion in a native coronary artery of >/=2.75 mm diameter were included. A total of 425 patients were allocated in 24 centers. Clinical data were collected at one-, six- and nine-month follow-up. Angiography was performed before and after the stent implantation. In addition, in the first 200 patients (SOPHOS A) angiography was routinely performed at six months. The following 225 patients (SOPHOS B) were merely followed up clinically. The primary end-point of the study, the six-month MACE-rate (MACE = Major Adverse Cardiac Events) was 13.4% (two cardiac death; five Q-wave/nine non-Q-wave myocardial infarctions (MI); nine CABG and 32 target lesion revascularization (TLR), which is similar to the calculated 15% MACE-rate in comparable reference studies. Secondary end-points included among others restenosis at six months in the SOPHOS A population. The target vessel diameter was 2.98 +/- 0.48 mm. Minimal lumen diameter pre/post procedure and at follow-up was 1.00 +/- 0.32, 2.69 +/- 0.37, 1.91 +/- 0.71 mm, respectively. The binary restenosis rate (>/=50% diameter stenosis at follow-up) was 17.7%. CONCLUSION: The coronary BiodivYsio stent is safe and effective as a primary device for the treatment of native coronary artery lesions in patients with stable or unstable angina pectoris. Clinical and angiographic results are in the statistical range of equivalence with comparable studies with other current stents.

A prospective randomized trial comparing stenting to internal mammary artery grafting for proximal, isolated de novo left anterior coronary artery stenosis: the SIMA trial. Stenting vs Internal Mammary Artery

OBJECTIVE

To compare coronary artery bypass grafting (CABG) with percutaneous transluminal coronary angioplasty (PTCA) in patients with proximal, isolated de novo left anterior descending coronary artery disease and left ventricular ejection fraction of 45%.

PATIENTS AND METHODS

In the multicenter Stenting vs Internal Mammary Artery (SIMA) study, patients were randomly assigned to PTCA and stent implantation or to CABG (using the internal mammary artery). The primary clinical composite end point was event-free survival, including death, myocardial infarction, and the need for additional revascularization. Secondary end points were functional class, antianginal treatment, and quality of life. Analyses were by intention to treat.

RESULTS

Of 123 patients who accepted randomization, 59 underwent CABG, and 62 were treated with stent implantation (2 patients were excluded because of protocol violation). At a mean +/- SD follow-up of 2.4+/-0.9 years, a primary end point had occurred in 19 patients (31%) in the stent group and in 4 (7%) in the CABG group (P<.001). This significant difference in clinical outcome is due to a higher incidence of additional revascularization in the stent group, the incidence of death and myocardial infarction being similar (7% vs 7%, respectively; P=.90). The functional class, need for antianginal drug, and quality-of-life assessment showed no significant differences.

CONCLUSIONS

Both stent implantation and CABG are safe and highly effective treatments to relieve symptoms in patients with isolated, proximal left anterior descending coronary artery stenosis. Both are associated with a low and comparable incidence of death and myocardial infarction. However, similar to PTCA alone, a percutaneous approach using elective stent placement remains hampered by a higher need for repeated intervention because of restenosis.

Two crystal structures of human neutrophil collagenase, one complexed with a primed- and the other with an unprimed-side inhibitor: implications for drug design

Two crystal structures of human neutrophil collagenase (HNC, MMP-8), one complexed with a primed- and the other with an unprimed-side inhibitor, were determined using synchrotron radiation at 100 K. Both inhibitors contain non-hydroxamate zinc-binding functions. The Pro-Leu-L-Trp(P)(OH)(2) occupies the unprimed region of the active site, furnishes new structural information regarding interaction between the catalytic zinc ion and the phosphonate group, and is the only example of occupation of the S(1) subsite of MMP-8 by the bulky tryptophan side chain. The (R)-2-(biphenyl-4-ylsulfonyl)-1,2,3, 4-tetrahydroisochinolin-3-carboxylic acid, a conformationally constrained D-Tic derivative, accommodates its biphenyl substituent into the deep primary specificity S(1)' subsite, inducing a widening of the entrance to this pocket; this modification of the protein, mainly consisting in a shift of the segment centered at Pro217, is observed for the first time in MMP-8 complexes. Cation-aromatic interactions can stabilize the formation of both complexes, and the beneficial effect of aromatic substituents in proximity of the catalytic zinc ion is discussed. The phosphonate group bound to either a primed- or unprimed-side inhibitor maintains the same relative position with respect to the catalytic zinc ion, suggesting that this binding function can be exploited for the design of combined inhibitors assembled to interact with both primed and unprimed regions of the active cleft.

Selection of cell specific peptides in a rat carotid injury model using a random peptide-presenting bacterial library

Cell specific peptides are possible candidates to enable targeted delivery of drugs and therapeutic genes in vivo. This study explores the utility of using a peptide-presenting bacterial library (pFliTrx) for the selection of new cell specific peptides, which bind to vascular cells of perfused tissues or organs. The balloon-injured rat carotid artery served as a model. Following perfusion of injured vascular segments with pFliTrx, 36 single clones could be identified. In radioligand binding studies, one of them, peptide P36, binds predominantly to perfused injured versus control vessel segments. It was additionally found that P36 binds with a 700-fold higher affinity in vitro to endothelial cells stimulated by treatment with LPS and TNF-alpha compared with unstimulated endothelial cells. The amino acid sequence of P36 reveals high homology to alpha(4)beta(1)-integrin, which mediates leukocyte migration from the vasculature at sites of inflammation via binding to cellular adhesion molecules, such as VCAM. In summary, this study demonstrates, that high specific peptides directed against injured vascular cells can be selected using a random peptide-presenting bacterial library.

The N-terminus of collagenase MMP-8 determines superactivity and inhibition: a relation of structure and function analyzed by biomolecular interaction analysis

Tissue inhibitors of metalloproteinases (TIMPs) are the physiological, specific inhibitors of matrix metalloproteinases (MMPs) forming tight, noncovalent complexes. Therefore they control the proteolytic activity of MMPs toward the extracellular matrix. To analyze the inhibition of the "activated" and "superactivated" variants of human neutrophil collagenase (MMP-8) by TIMP-2, we determined complex dissociation constants using biomolecular interaction analysis (BIA). As it is known that the association rate constants can exceed the limits of the BIA instruments, the biomolecular interaction analysis was used to examine the equlibrium situation. The dissociation constants were determined by fitting the parameters of the mathematical term for the binding of collagenase onto the TIMP-coupled sensor chip surface to the saturation curve derived from individual sensorgrams. The resulting values are in the nanomolar range and correlate with the results of fluorescence kinetics. These data reveal that TIMP-2 (the recombinant inhibitory domain of human TIMP-2 and bovine TIMP-2 isolated from seminal plama) is a better inhibitor of the activated neutrophil collagenase than of the superactivated variant (the recombinant catalytic domain of human MMP-8). It has been demonstrated by X-ray analysis that the N-terminal heptapeptide only of superactivated MMP-8 is attached by a salt bridge and hydrophobic interaction to the C-terminal helix. Because these interactions have to be disrupted in the complex formation with TIMP we assume that the activated variant enables higher flexibility and a tighter induced fit in the complex formation. Therefore superactivation of MMP-8 correlates with weaker inhibition by TIMP-2.

Comparisons of eye movements before and after a speed-reading course

BACKGROUND

The techniques of speed reading are widely used and generally accepted, but few studies have investigated whether- and how-speed reading actually improves reading ability in the typical reader.

METHODS

Using the Ober2, an infrared monitoring device that accurately tracks eye movements, we measured the eye movements of 59 students. The Ober2 calculates reading speed, number of fixations per 100 words, number of words seen in each fixation, number of regressions per 100 words, and duration of fixation. Comprehension was assessed with ten detailed true or false questions.

RESULTS

One group of the students (n = 25) participated in a speed reading class; the other group (n = 34) did not. After completion of the course, all 59 were re-measured on the Ober2. The speed-reading group improved significantly in five of the six aspects tested. Comprehension for the speed reading group showed an insignificant decrease.

CONCLUSIONS

We conclude that measurable changes in reading eye movements accompany successful completion of a speed-reading course.

Percutaneous transluminal therapy of occluded saphenous vein grafts: can the challenge be met with ultrasound thrombolysis?

BACKGROUND

Percutaneous transluminal treatment of a thrombotic vein graft yields poor results. We have previously reported our experience with transluminal percutaneous coronary ultrasound thrombolysis (CUT) in the setting of acute myocardial infarction (AMI). This report describes the first experience with ultrasound thrombolysis in thrombus-rich lesions in saphenous vein grafts (SVGs), most of which were occluded.

METHODS AND RESULTS

The patients (n=20) were mostly male (85%), aged 64+/-4 years old. The presenting symptom was AMI in 2 patients (10%) and unstable angina in the rest. Fifteen patients (75%) had totally occluded SVGs. The median age of clots was 6 days (range, 0 to 100 days). The ultrasound thrombolysis device has a 1.6-mm-long tip and fits into a 7F guiding catheter over a 0.014-in guidewire in a "rapid-exchange" system. CUT (41 kHz, 18 W, </=6 minutes) led to device success in 14 (70%) of the patients and residual stenosis of 65+/-28%. Procedural success was obtained in 13 (65%) of the patients, with a final residual stenosis of 5+/-8%. There was a low rate of device-related adverse events: 1 patient (5%) had a non-Q-wave myocardial infarction, and distal embolization was noted in 1 patient (5%). Adjunct PTCA or stenting was used in all patients. There were no serious adverse events during hospitalization.

CONCLUSIONS

Ultrasound thrombolysis in thrombus-rich lesions in SVGs offers a very promising therapeutic option.

Randomized evaluation of anticoagulation versus antiplatelet therapy after coronary stent implantation in high-risk patients: the multicenter aspirin and ticlopidine trial after intracoronary stenting (MATTIS)

BACKGROUND

Although the association of ticlopidine and aspirin has been shown to be superior to anti-vitamin K agents and aspirin after coronary stent implantation in low-risk patients, the latter combination has remained an unproven reference regimen for high-risk patients until recently.

METHODS AND RESULTS

We randomized 350 high-risk patients within 6 hours after stent implantation to receive during 30 days either aspirin 250 mg and ticlopidine 500 mg/d (A+T group) or aspirin 250 mg/d and oral anticoagulation (A+OAC group) targeted at an international normalized ratio of 2.5 to 3. The primary composite end point was defined as the occurrence of cardiovascular death, myocardial infarction, or repeated revascularization at 30 days. Patients were eligible if (1) the stent(s) were implanted to treat abrupt closure after PTCA; (2) the angiographic result after implantation was suboptimal; (3) a long segment was stented (>45 mm and/or >/=3 stents); or (4) the largest balloon inflated in the stent had a nominal diameter of </=2.5 mm. The primary cardiac end point was reached for 10 patients (5.6%) in the A+T group and 19 (11%) in the A+OAC group (relative risk [RR], 1. 9; 95% CI, 0.9 to 4.1; P=0.07). Major vascular and bleeding complications were less frequent in the A+T group (3 patients, 1.7%) than in the A+OAC group (12 patients, 6.9%) (RR, 4.1; 95% CI, 1.2 to 14.3; P=0.02).

CONCLUSIONS

High-risk patients should be treated with A+T rather than A+OAC after coronary stenting because the bleeding and vascular complications are significantly reduced and there is a marked trend suggesting a decrease in cardiac events.

Expression, purification, characterization, and X-ray analysis of selenomethionine 215 variant of leukocyte collagenase

Matrix metalloproteinases belong to the superfamily of metzincins containing, besides a similar topology and a strictly conserved zinc environment, a 1,4-tight turn with a strictly conserved methionine residue at position three (the so called Met-turn [Bode et. al. (1993) FEBS 331, 134-140; Stöcker et al. (1995) Protein Sci. 4, 823-840]. The distal S-CH3 moiety of this methionine residue forms the hydrophobic basement of the three His residues liganding the catalytic zinc ion. To assess the importance of this methionine, we have expressed the catalytic domain of neutrophil collagenase (rHNC, residues Met80-Gly242) in the methionine auxotrophic Escherichia coli strain B834[DE3](hsd metB), with the two methionine residues replaced by selenomethionine. Complete replacement was confirmed by amino acid analysis and electrospray mass spectrometry. The folded and purified enzyme retained its catalytic activity, but showed modifications which are reflected in change kinetic parameters. The Met215SeMet substitution caused a decrease in conformational stability upon area denaturation. The X-ray crystal structure of this selenomethionine rHNC was virtually identical to that of the wild-type catalytic domain except for a very faint local disturbance around the sulfur-seleno substitution site.

1.8-A crystal structure of the catalytic domain of human neutrophil collagenase (matrix metalloproteinase-8) complexed with a peptidomimetic hydroxamate primed-side inhibitor with a distinct selectivity profile

Matrix metalloproteinases (MMP) are zinc endopeptidases involved in tissue remodelling. They have been implicated in a series of pathologies, including cancer, arthritis, joint destruction and Alzheimer's disease. Human neutrophil collagenase represents one of the three interstitial collagenases that cleave triple-helical collagen of type I, II and III. Its catalytic domain (residues Phe79-Gly242) has been heterologously expressed in Escherichia coli and crystallized as a non-covalent complex with the hydroxamate inhibitor BB-1909, which has distinct selectivity against different MMP, in a crystal form. The crystal structure, refined to 0.18-nm resolution, shows that BB-1909 is a right-hand-side inhibitor that binds to the S1'-S3' subsites and coordinates to the catalytic Zn2+ in a bidentate manner via the hydroxyl and carbonyl oxygen atoms of the hydroxamate group in a similar manner to batimastat. The collagenase/BB-1909 complex is described in detail and compared with the collagenase/batimastat complex. These studies provide information on MMP specificity and thus may assist the development of more-selective MMP inhibitors.

Removal of thrombus from aortocoronary bypass grafts and coronary arteries using the 6Fr Hydrolyser

This study evaluates the feasibility and safety of a 6Fr hydrodynamic thrombectomy catheter, the Hydrolyser, in native coronary arteries and aortocoronary bypass grafts. With use of a conventional contrast injector, saline solution is injected into the narrow lumen of the catheter which makes a 180 degrees bend at the tip. The resultant high-velocity jet (150 km/hour) is directed over a sidehole near the tip into a wide exhaust lumen. As a consequence of the Venturi effect, thrombus is sucked into that sidehole, fragmented, and removed through the wide exhaust lumen into a collection bag. Thirty-one thrombotic lesions were treated in 31 patients. The culprit vessel was a venous graft in 21 patients (15 with Thrombolysis in Myocardial Infarction Trial [TIMI] grade 0 or 1 flow) and a coronary artery in 11 patients (9 with grade 0 or 1 flow). Twenty-six patients had angina New York Heart Association functional class III or IV heart failure and 5 an acute myocardial infarction. In 26 patients, Hydrolyser therapy was the primary treatment, whereas in 5 patients coronary angioplasty preceded Hydrolyser therapy. In 1 patient the Hydrolyser could not reach the lesion. Thrombus was removed in 29 of the 31 patients. Successful reperfusion (TIMI grade 2 or 3 flow) by Hydrolyser therapy alone was achieved in 14 of the 24 patients with TIMI grade 0 or 1 flow before the procedure. Adjunctive therapy (coronary angioplasty, stent, or thrombolysis) was performed in 28 of the 31 patients. At the end of the total procedure 24 patients had TIMI grade 3 flow. Distal embolization during thrombectomy occurred in 2 patients, which led to a non-Q-wave infarction in 1. No patient died or needed emergency coronary bypass due to the Hydrolyser procedure. Thus, thrombectomy using the 6Fr Hydrolyser is feasible and was performed safely in 31 patients.

Design and synthesis of heterotrimeric collagen peptides with a built-in cystine-knot. Models for collagen catabolism by matrix-metalloproteases

A heterotrimeric collagen peptide was designed and synthesized which contains the collagenase cleavage site (P4-P'9/10) of type I collagen linked to a C-terminal cystine-knot, and N-terminally extended with (Gly-Pro-Hyp)5 triplets for stabilization of the triple-helical conformation. By employing a newly developed regioselective cysteine pairing strategy based exclusively on thiol disulfide exchange reactions, we succeeded in assembling in high yields and in a reproducible manner the triple-stranded cystine peptide. While the single chains showed no tendency to self-association into triple helices, the heterotrimer (alpha1 alpha2 alpha1') was found to exhibit a typical collagen-like CD spectrum at room temperature and a melting temperature (Tm) of 33 degrees C. This triple-helical collagen-like peptide is cleaved by the full-length human neutrophil collagenase (MMP-8) at a single locus fully confirming the correct raster of the heterotrimer. Its digestion proceeds at rates markedly higher than that of a single alpha1' chain. In contrast, opposite digestion rates were measured with the catalytic Phe79-MMP-8 domain of HNC. Moreover, the full-length enzyme exhibits Km values of 5 microM and 1 mM for the heterotrimer and the single alpha1' chain, respectively, which compare well with those reported for collagen type I (approximately 1 microM), gelatine (approximately 10 microM) and for octapeptides of the cleavage sequence (> or = 1 mM). The high affinity of the MMP-8 for the triple-helical heterotrimer and the fast digestion of this collagenous peptide confirm the decisive role of the hemopexin domain in recognition and possibly, partial unfolding of collagen.

Structure determination and analysis of human neutrophil collagenase complexed with a hydroxamate inhibitor

Matrix metalloproteinases are a family of zinc endopeptidases involved in tissue remodeling. They have been implicated in various disease processes including metastasis, joint destruction, and neurodegeneration. Human neutrophil collagenase (HNC, MMP-8) represents one of the three "interstitial" collagenases that cleave triple-helical collagens types I, II, and III. Its 163-residue catalytic domain (Met80 to Gly242) has been expressed in Escherichia coli and crystallized as a noncovalent complex with the hydroxamate inhibitor batimastat. The crystal structure, refined to 2.1 A, demonstrates that batimastat binds to the S1-S2' sites and coordinates to the catalytic zinc in a bidentate manner via the hydroxyl and carbonyl oxygens of the hydroxamate group. The batimastat-collagenase complex is described in detail, and the activities of batimastat analogues are discussed in the light of the protein-inhibitor interactions revealed by the crystallography studies.

[Arthroscopic synovectomy of the knee joint in chronic juvenile arthritis]

We report on arthroscopic synovectomy of 19 knee joints in juvenile chronic arthritis with a mean follow-up of 2.2 years (1 to 4 years). In 15 cases the disease course was pauciarticular. Fourteen knee joints showed significant destructive lesions already preoperatively. In two-thirds of patients, we found a good or satisfactory result concerning especially reduction of synovial swelling and effusion. Eleven knee joints also received a significant functional improvement. Indication for arthroscopic synovectomy is given mainly in highly active mon- or pauciarthritis if conservative treatment remained insufficient. Of special importance is an intensive postoperative physiotherapy.