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PubMed1988

Left ventricular outflow obstruction after mitral valve repair (Carpentier's technique). Proposed mechanisms of disease.

Left ventricular outflow tract obstruction (LVOTO) after mitral valve repair by Carpentier's technique has been recently reported in the literature. To assess the mechanisms of this phenomenon, we investigated 307 mitral valve repairs performed between July 1985 and December 1986. Incidence of LVOTO related to the mechanism of the mitral insufficiency and to the etiology demonstrates a direct relation to preoperative mitral valve prolapse (posterior leaflet +/- anterior leaflet) of degenerative origin. No LVOTO occurred after rheumatic mitral insufficiency repair regardless of size of the left heart cavities or of the prosthetic ring. Intraoperative and surficial two-dimensional echocardiography, color Doppler methods, and cardiac catheterization were used to investigate the mechanisms leading to LVOTO. Nonspecific modifications induced by reduction in size of the mitral annulus by the prosthetic ring (anterior displacement of the posterior ventricular wall and of the posterior mitral leaflet and narrowing of the mitroaortic angle) are not sufficient to explain the LVOTO. The association of mitral leaflets (composed of excess tissue and opposed to flow by a perpendicular position attributable to a narrow mitroaortic angle) and geometric left ventricular modifications (responsible for the superposition of mitral inflow to ventricular outflow) also qualifies as a mechanism for the induction of LVOTO after mitral surgical repair.

Cardiac Catheterization↗

PubMed1993

Description and measurement of anatomical joint motion.

Recently, three-dimensional measurement of human movement has become practically available due to the development of sensor techniques, and the miniaturization and cost reduction of computers. As well as accurate and reliable sensors, powerful and inexpensive computers are indispensable for processing the large quantity of motion data that must be obtained. Measurement and analysis of anatomical joint motion would be useful for the evaluation of diseases, outcome of surgical operations and effects of rehabilitation, as well as for training in sports activities. The present article reviews the mathematical description and measurement of anatomical joint motion.

Biomechanical Phenomena↗

PubMed1997

[Determination of in vitro synergy when amphotericin B is combined with various antimicrobial agents against yeasts by using a colorimetric microdilution checkerboard].

We determined in vitro interactions when amphoteric B (AMPH) is combined with various antimicrobial agents against yeast by using a colorimetric microdilution transfer plate technique, principally based on the current National Committee for Clinical Laboratory Standards (NCCLS) M27-T. An oxidation-reduction dye, sodium resazurin, was used as a color indicator to detect the growth of yeasts, and a standard two-dimensional, two-agent microdilution checkerboard in RPMI 1640 was employed to determine in vitro interactions; synergistic, indifferent or antagonistic. The study included 125 clinical isolates of Candida species and nine reference strains of American Type Culture Collection described in M27-T. Among the 34 antimicrobial agents first tested, polymyxin B (PL), rifampicin (RFP), tetracycline (TC) and erythromycin (EM) showed significant synergism. The fractional inhibitory concentration (FIC) indices of the respective agents were; PL 0.16 to 0.51 (mean, 0.315), RFP 0.13 to 0.56 (0.255), TC 0.06 to 0.75 (0.353) and EM 0.27 to 1.0 (0.550). RFP was the most potent agent, 118 of 125 clinical isolates (94.4%) showing synergism (FIC, < or = 0.5). With these results, we can conclude that several antibacterial agents are potentially effective when combined with AMPH against yeasts, probably due to alteration in the permeability barrier of the surface membrane by AMPH. Antifungal synergism may be promising for more effective, and less toxic therapy, and thus in vivo study will be necessary to determine their clinical significance.

Amphotericin B↗

PubMed2006

Bone microarchitecture in males with corticosteroid-induced osteoporosis.

SUMMARY: Microarchitectural changes in trabecular bone were analyzed by microcomputed tomography (microCT) and histomorphometry in 24 patients with corticosteroid-induced osteoporosis. The microCT images revealed a reduction in trabecular thickness only on frequency distribution curves, with no increase in trabecular separation. Trabecular plate thinning and perforations were easily identified. INTRODUCTION: Corticosteroid-induced osteoporosis (CSIOP) is mediated by direct actions of the drug on bone cells. The result is a decrease in trabecular bone mass and a reduction in trabecular thickness, but connectivity is believed to remain rather well preserved. METHODS: Twenty-four transiliac bone biopsies from patients with CSIOP were studied conjointly by histomorphometry [with two-dimensional (2D) architectural descriptors] and microCT (with 3D analysis of trabecular characteristics, including trabecular thickness and separation). The frequency distribution of thickness and separation were compared with data obtained in nine control subjects. RESULTS: 2D histomorphometry revealed a decrease in bone volume and trabecular thickness in the bone biopsies of the CSIOP patients when compared to those of the controls. MicroCT appeared to be able to identify the reduction in thickness only when the frequency distribution of trabecular thickness was computed. No difference for the curves of the frequency distribution of trabecular separation was evidenced between patients and controls. MicroCT and 2D histomorphometric results were correlated, but 2D analysis appeared to be more sensitive. However, microCT identified a very specific thinning of the trabecular plates in their center that corresponds to the earlier stages of perforations. CONCLUSION: Trabecular plate thinning can be observed and perforations occur on very thin plates in CSIOP patients.

Adrenal Cortex Hormones↗

PubMed2005

Performance of the improved version of monte Carlo code A3MCNP for large-scale shielding problems.

A3MCNP (Automatic Adjoint Accelerated MCNP) is a revised version of the MCNP Monte Carlo code, which automatically prepares variance reduction parameters for the CADIS (Consistent Adjoint Driven Importance Sampling) methodology. Using a deterministic 'importance' (or adjoint) function, CADIS performs source and transport biasing within the weight-window technique. The current version of A3MCNP uses the three-dimensional (3-D) Sn transport TORT code to determine a 3-D importance function distribution. Based on simulation of several real-life problems, it is demonstrated that A3MCNP provides precise calculation results with a remarkably short computation time by using the proper and objective variance reduction parameters. However, since the first version of A3MCNP provided only a point source configuration option for large-scale shielding problems, such as spent-fuel transport casks, a large amount of memory may be necessary to store enough points to properly represent the source. Hence, we have developed an improved version of A3MCNP (referred to as A3MCNPV) which has a volumetric source configuration option. This paper describes the successful use of A3MCNPV for a concrete cask neutron and gamma-ray shielding problem, and a PWR dosimetry problem.

Algorithms↗

PubMed1992

Coronary artery stenosis provokes non-uniformity of two-dimensional deformation in the anterior wall of the feline left ventricle.

The effect of coronary stenosis on the uniformity of local left ventricular contraction was studied in 11 open-chest cats. Coronary artery stenosis was established by controlled constriction of a shunt line from the right subclavian artery to the left main coronary artery. Two pairs of ultrasonic crystals were placed in the midwall of the anterior left ventricular wall; one pair, circumferential (Circ), aligned with midwall and subepicardial fibres; the other, longitudinal (Long), aligned with subendocardial fibres. Three steps of coronary perfusion pressure (poststenotic) were studied; open shunt line (140 +/- 4 mmHg), light stenosis (94 +/- 2 mmHg), and severe stenosis (70 +/- 3 mmHg). Subendocardial tissue blood flow showed the most pronounced reduction (from 1.87 +/- 0.11 to 1.43 +/- 0.10 and 0.86 +/- 0.12 ml min-1 g-1, respectively) with coronary stenosis whereas subepicardial flow remained unchanged. Maximal systolic shortening deteriorated for both segments. However, it was most pronounced for longitudinal segments. Duration of shortening decreased in longitudinal segments during severe stenosis to 62% of duration with open shunt (P less than 0.05), but was unchanged in circumferential segments. Long/Circ ratio of maximal systolic shortening declined by 50% (P less than 0.05) with reduction of coronary perfusion pressure. The reduced uniformity of segment shortening, caused by a marked reduction of longitudinal segment shortening, may support the notion that the longitudinal segment reflects performance of subendocardial fibres. This study demonstrates local non-uniformity of two-dimensional deformation during coronary artery stenosis and subendocardial hypoperfusion.

Animals↗

PubMed2006

One-dimensional self-assembly of alkoxy-capped silicon nanoparticles.

We demonstrate here a novel method for self-assembling in dimensional alignment the alkoxy-capped silicon nanoparticles synthesized through a room-temperature chemical route. The alkoxy-capped silicon nanoparticles were prepared via a reduction of silicon tetrachloride with sodium-naphthalide and subsequent surface capsulation with 1-octanol monolayers. In the present method, a sublimation process, which was employed as a final purification process for removing the residual naphthalene, influenced significantly on the final morphology of the resultant nanoparticles. Scanning transmission electron microscope (STEM) confirmed the spherical nanoparticles on a holey carbon grid after sublimation process, while only the fibril-like morphology just before sublimation process. In the former sample, the resultant particle size was measured by STEM to be about 9.5 nm +/- 3.4 nm. On the other hand, in the latter sample, the fibril-like structures were shaped by self-assembled silicon nanoparticles in dimensional alignment. The diameters and lengths of the fibril-like assemblies were approximately measured to be 10 to 20 nm and over 5 microm, respectively.

1-Octanol↗

PubMed1989

Thiol-sensitive genes of Escherichia coli.

The effect of 1-thioglycerol on the expression of genes of Escherichia coli was investigated. Pulse-labeled proteins from aerobically growing, 1-thioglycerol-treated E. coli were separated by two-dimensional gel electrophoresis, and their radioactivities were compared with those of identical proteins from nontreated cells. The first 10 min of exposure to thiol stimulated the synthesis of 10% of the observed proteins and inhibited the production of 16% of the proteins. After 30 min of growth with thiol, the synthesis of 44% of the observed proteins was inhibited and synthesis of 18% of the proteins was stimulated. In general, the expression of genes of carbohydrate metabolism, amino acid metabolism, and protein biosynthesis were inhibited, while nucleic acid synthetic and repair gene expressions showed mixed responses. Synthesis of transport proteins was not affected. Transient stimulation of oxidative-stress proteins and sustained stimulation of the expressions of trxB, ompA, and ompB genes and those of several unidentified gene products were also observed. Whether these complex responses merely reflect adjustments by cellular subsystems to a suddenly reducing environment or whether they are manifestations of a reductive-stress regulon will have to await genetic analysis of this phenomenon.

Bacterial Proteins↗

PubMed2003

Rapamycin reduces neointima formation during vascular injury.

BACKGROUND: Proliferation and migration of vascular smooth muscle cells (SMCs) mark the key processes in the development of bypass graft disease and during neointima formation in restenosis after angioplasty. Growth factors are potent SMC mitogens as they are involved in SMC proliferation and in extracellular matrix (ECM) synthesis. Based on these premises, we examined the effect of the proliferation inhibitor rapamycin in human SMC culture and in a rabbit vascular injury model. MATERIALS AND METHODS: Injection of rapamycin or its vehicle was performed with an infusion-balloon catheter directly into the vessel wall during vascular injury. The intima/media ratio was determined histologically whereas the protein expression was analysed using the powerful two-dimensional gel electrophoresis (2D page) technique. Inhibition of proliferation after rapamycin application was estimated in a human SMC culture for time and dose dependent effects. RESULTS: Rapamycin treatment resulted in a significant reduction of intima media ratio compared to vehicle treated animals after three weeks (0.65 +/- 0.1 vs. 1.2 +/- 0.2 intima-media-ratio, p < 0.05). 2D electrophoresis analysis proved increased ECM synthesis following angioplasty (i.e., lamin, vimentin) in vehicle treated animals. Local rapamycin administration resulted in profound reduction of ECM synthesis after vascular injury. In in-vitro experiments exposure of cultured human SMCs to rapamycin resulted in a significant and dose-dependent (1 nm-100 nm) reduction of human smooth muscle cell proliferation measured by cell counting. CONCLUSION: These above mentioned results suggest that protein synthesis in addition to reduction of cellular proliferation plays an important role following vascular injury, since application of rapamycin resulted in the reduction of SMC proliferation and ECM-synthesis.

Angioplasty, Balloon↗

PubMed1992

Microsensor measurements of sulfate reduction and sulfide oxidation in compact microbial communities of aerobic biofilms.

The microzonation of O(2) respiration, H(2)S oxidation, and SO(4) reduction in aerobic trickling-filter biofilms was studied by measuring concentration profiles at high spatial resolution (25 to 100 mum) with microsensors for O(2), S, and pH. Specific reaction rates were calculated from measured concentration profiles by using a simple one-dimensional diffusion reaction model. The importance of electron acceptor and electron donor availability for the microzonation of respiratory processes and their reaction rates was investigated. Oxygen respiration was found in the upper 0.2 to 0.4 mm of the biofilm, whereas sulfate reduction occurred in deeper, anoxic parts of the biofilm. Sulfate reduction accounted for up to 50% of the total mineralization of organic carbon in the biofilms. All H(2)S produced from sulfate reduction was reoxidized by O(2) in a narrow reaction zone, and no H(2)S escaped to the overlying water. Turnover times of H(2)S and O(2) in the reaction zone were only a few seconds owing to rapid bacterial H(2)S oxidation. Anaerobic H(2)S oxidation with NO(3) could be induced by addition of nitrate to the medium. Total sulfate reduction rates increased when the availability of SO(4) or organic substrate increased as a result of deepening of the sulfate reduction zone or an increase in the sulfate reduction intensity, respectively.

Journal Article↗

PubMed2001

Entorhinal cortex atrophy in epilepsy patients exhibiting normal hippocampal volumes.

OBJECTIVE: To determine whether MRI volumetric measurement of the entorhinal cortex could detect structural damage and lateralize the seizure focus in patients with temporal lobe epilepsy in whom no measurable hippocampal abnormalities were found. BACKGROUND: A reduction in the volume of the entorhinal cortex ipsilateral to the seizure focus in patients with intractable temporal lobe epilepsy and hippocampal atrophy was recently shown. METHODS: MRI volumetric analysis of the entorhinal cortex was performed using a T1-weighted three-dimensional gradient echo sequence in 24 control subjects and 22 patients with temporal lobe epilepsy and normal hippocampal volumes. Thirteen patients underwent surgery, with a mean postoperative follow-up of 36 months. RESULTS: Group analysis (multivariate analysis of variance) showed a reduction in the volume of the entorhinal cortex ipsilateral to the seizure focus in patients with left (p < 0.0001) and right temporal lobe epilepsy (p < 0.0001). Lateralization of the seizure focus could be done in 14 of 22 patients (64%) based on entorhinal cortex volumetry. CONCLUSION: Entorhinal cortex atrophy ipsilateral to the seizure focus supports the presence of structural damage in the mesial temporal lobe in patients with temporal lobe epilepsy and normal hippocampal volumes and emphasizes the participation of the entorhinal cortex in the pathogenesis of this disorder.

Adult↗

PubMed1998

Intracranial volume in craniosynostotic rabbits.

Although craniosynostosis alters brain growth direction resulting in compensatory changes in the neurocranium, it has been suggested that such compensations occur with little reduction in intracranial volume (ICV). This hypothesis was tested in a rabbit model with nonsyndromic, familial coronal suture synostosis. Cross-sectional three-dimensional computed tomographic head scans were obtained from 79 rabbits (25 normal, 28 with delayed-onset synostosis, and 26 with early-onset synostosis) at 25, 42, and 126 days of age. Intracranial contents were reconstructed and indirect ICV was calculated. Results revealed that by 25 days of age the intracranial contents from early-onset synostosed rabbit skulls showed rostral (anterior) constrictions and a "beaten copper" morphology in the parietal and temporal regions compared with the other two groups. These deformities increased in severity with age. Quantitatively, ICV was significantly reduced (P < 0.05) by 7% in rabbits with early-onset synostosis compared with both control rabbits and rabbits with delayed-onset synostosis at 25 days of age. By 126 days of age, ICV in rabbits with synostosis was significantly reduced (p < 0.05) by 11% in early-onset synostosis and by 8% in delayed-onset synostosis compared with normal rabbits. Results suggest that in rabbits with uncorrected craniosynostosis, compensatory changes in the neurocranium were not adequate to allow normal expansion of the neurocapsular matrix. Further research is needed to determine if ICV reduction is correlated with cerebral atrophy or cerebral spinal fluid (i.e., ventricular or subarachnoid) space compression in this model.

Age of Onset↗

PubMed1996

Contribution of sustained Ca2+ elevation for nitric oxide production in endothelial cells and subsequent modulation of Ca2+ transient in vascular smooth muscle cells in coculture.

To elucidate the intracellular Ca2+ (Ca2+i ) transient responsible for nitric oxide (NO) production in endothelial cells (ECs) and the subsequent Ca2+i reduction in vascular smooth muscle cells (VSMCs), we administrated four agonists with different Ca2+i-mobilizing mechanisms for both cells in iso- or coculture. We monitored the Ca2+i of both cells by two-dimensional fura-2 imaging, simultaneously measuring NO production as NO2-. The order of potency of the agonists in terms of the peak Ca2+i in ECs was bradykinin (100 nM) > ATP (10 microM) > ionomycin (50 nM) > thapsigargin (1 microM). In contrast, the order in reference to both the extent of Ca2+i reduction in cocultured VSMCs and the elevation in NO production over the level of basal release in ECs completely matched and was ranked as thapsigargin > ionomycin > ATP > bradykinin. Treatment by NG-monomethyl-L-arginine monoacetate but not indomethacin or glybenclamide restored the Ca2+i response in cocultured VSMCs to the isoculture level. In ECs, when the Ca2+ influx was blocked by Ni2+ or by chelating extracellular Ca2+, all four agonists markedly decreased NO production, the half decay time of the Ca2+i degenerating phase, and the area under the Ca2+i curve. The amount of produced NO hyperbolically correlated to the half decay time and the area under the Ca2+i curve but not to the Ca2+i peak level. Thus, the sustained elevation of Ca2+i in ECs, mainly a result of Ca2+ influx, determines the active NO production and subsequent Ca2+i reduction in adjacent VSMCs. Furthermore, L-arginine but not D-arginine or L-lysine at high dose (5 mM) without agonist enhanced the NO production, weakly reduced the Ca2+i in ECs, and markedly decreased the Ca2+i in VSMCs, demonstrating the autocrine and paracrine effects of NO (Shin, W. S., Sasaki, T., Kato, M., Hara, K., Seko, A., Yang, W. D., Shimamoto, N., Sugimoto, T., and Toyo-oka, T. (1992) J. Biol. Chem. 267, 20377-20382).

Animals↗

PubMed1991

Sustained reduction in valvular regurgitation and atrial volumes with tailored vasodilator therapy in advanced congestive heart failure secondary to dilated (ischemic or idiopathic) cardiomyopathy.

Afterload reduction therapy can acutely improve hemodynamic function in patients with advanced heart failure; however, it is unknown if initial reductions in mitral and tricuspid regurgitation and atrial volumes can be sustained with oral therapy. Atrial volumes and atrioventricular valve regurgitation were measured using 2-dimensional and Doppler echocardiography with color-flow imaging in 14 patients with dilated heart failure (ejection fraction 17 +/- 4%) before and after 3 +/- 1 days of intensive vasodilator and diuretic therapy tailored to hemodynamic goals. Echocardiography was repeated again after 6 +/- 2 months on oral vasodilators and a flexible diuretic regimen. Acute therapy reduced systemic vascular resistance from 1,760 +/- 460 to 1,010 +/- 310 dynes.s.cm-5, pulmonary artery wedge pressure from 30 +/- 5 to 17 +/- 4 mm Hg, and right atrial pressure from 13 +/- 5 to 7 +/- 3 mm Hg, and led to a 61% increase in stroke volume (from 36 +/- 10 to 58 +/- 14 ml) (p less than 0.01). Mitral and tricuspid regurgitation, determined by color-flow fraction, initially decreased from 0.34 +/- 0.17 to 0.20 +/- 0.20 and from 0.33 +/- 0.15 to 0.13 +/- 0.13, respectively (p less than 0.001). This reduction was sustained at 6 months. Significant decreases occurred with acute therapy, with further reductions at 6 months in both mean left atrial volume (from 100 +/- 25 to 80 +/- 19 to 65 +/- 15 cm3) and right atrial volume (from 85 +/- 23 to 64 +/- 23 to 52 +/- 14 cm3) (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗

PubMed2004

Residual fibrosis affects a long-term result of left ventricular volume reduction surgery for dilated cardiomyopathy in a rat experimental study.

OBJECTIVES: The aim of this study is to evaluate the relationship between left ventricular (LV) wall property and the results of LV volume reduction surgery (LVR) to treat dilated cardiomyopathy (DCM) in an experimental model. METHODS: DCM was introduced in 18 Lewis rats by autoimmunization with cardiac myosin. Among them, 12 rats underwent LVR and the rest were served as controls. They were subjected to echocardiography and cardiac catheterization for dimensional and functional measurements. The animals were sacrificed 4 weeks after surgery, and the fraction of myocardial fibrosis was calculated in 4 divided parts of the LV wall. RESULTS: Percent fibrosis varied widely from 4.7 to 45.2%. LV volume reduction surgery improved cardiac function immediately after surgery in all rats (Emax, 0.28+/-0.14 to 0.48+/-0.18 mmHg/microl; LV end-diastolic pressure, 21.0+/-6.1 to 13.3+/-5.1 mmHg, P<0.05, respectively). Four weeks later, 6 hearts remained in good shape with smaller LV end-diastolic dimension (Dd) than baseline values (LV Dd, 9.7+/-0.6mm; fractional area change (FAC), 40.3+/-8.4%) and the other 6 had more redilation in diameter and more deterioration in function than baseline values (LV Dd, 10.9+/-0.6mm; FAC, 25.8+/-6.9%; P<0.05, respectively). Percent fibrosis in the septum differed 11.1+/-3.4 vs. 27.8+/-2.8% between the two groups (P<0.01). There was a significant correlation between the ratio of LV redilatation after surgery and percent fibrosis in the septum (r=0.951, P<0.01). CONCLUSIONS: Although the initial benefit of LVR was confirmed, the long-term result was affected by the amount of residual fibrosis. This information suggests that surgical site selection is important to achieve a good result of LV restoration surgery for DCM.

Animals↗

PubMed2005

On FastMap and the convex hull of multivariate data: toward fast and robust dimension reduction.

FastMap is a dimension reduction technique that operates on distances between objects. Although only distances are used, implicitly the technique assumes that the objects are points in a p-dimensional Euclidean space. It selects a sequence of k < or = p orthogonal axes defined by distant pairs of points (called pivots) and computes the projection of the points onto the orthogonal axes. We show that FastMap uses only the outer envelope of a data set. Pivots are taken from the faces, usually vertices, of the convex hull of the data points in the original implicit Euclidean space. This provides a bridge to results in robust statistics, where the convex hull is used as a tool in multivariate outlier detection and in robust estimation methods. The connection sheds new light on the properties of FastMap, particularly its sensitivity to outliers, and provides an opportunity for a new class of dimension reduction algorithms, RobustMaps, that retain the speed of FastMap and exploit ideas in robust statistics.

Algorithms↗

PubMed2003

Invariant manifolds of an autonomous ordinary differential equation from its generalized normal forms.

A method to approximate some invariant sets of dynamical systems defined through an autonomous m-dimensional ordinary differential equation is presented. Our technique is based on the calculation of formal symmetries and generalized normal forms associated with the system of equations, making use of Lie transformations for smooth vector fields. Once a symmetry is determined up to a certain order, a reduction map allows us to pass from the equation in normal form to a related equation in a certain reduced space, the so-called reduced system of dimension s<m. Now, under certain regularity conditions, a nondegenerate p-dimensional invariant set of the reduced system is formally transformed into a (p+m-s)-dimensional invariant set of the original equation. Moreover, the existence of some actual (p+m-s)-dimensional invariant manifolds of the initial equations related to the ones determined through our analysis can be proven under certain hypotheses that we make explicit. The procedure is illustrated by characterizing the set of all periodic orbits sufficiently close to the origin of the Hamiltonian vector field defined by the Henon and Heiles family.

Algorithms↗

PubMed2005

2-Haloacrylate reductase, a novel enzyme of the medium chain dehydrogenase/reductase superfamily that catalyzes the reduction of a carbon-carbon double bond of unsaturated organohalogen compounds.

A soil bacterium, Burkholderia sp. WS, grows on 2-chloroacrylate as the sole carbon source. To identify the enzymes metabolizing 2-chloroacrylate, we carried out comparative two-dimensional gel electrophoresis of the proteins from 2-chloroacrylate- and lactate-grown bacterial cells. As a result, we found that a protein named CAA43 was inducibly synthesized when the cells were grown on 2-chloroacrylate. The CAA43 gene was cloned and shown to encode a protein of 333 amino acid residues (M(r) 35,788) that shared a significant sequence similarity with NADPH-dependent quinone oxidoreductase from Escherichia coli (38.2% identity). CAA43 was overproduced in E. coli and purified to homogeneity. The purified protein catalyzed the NADPH-dependent reduction of the carbon-carbon double bond of 2-chloroacrylate to produce (S)-2-chloropropionate, which is probably further metabolized to (R)-lactate by (S)-2-haloacid dehalogenase in Burkholderia sp. WS. NADH did not serve as a reductant. Despite the sequence similarity to quinone oxidoreductases, CAA43 did not act on 1,4-benzoquinone and 1,4-naphthoquinone. 2-Chloroacrylate analogs, such as acrylate and methacrylate, were also inert as the substrates. In contrast, 2-bromoacrylate served as the substrate. Thus, we named this novel enzyme 2-haloacrylate reductase. This study revealed a new pathway for the degradation of unsaturated organohalogen compounds. It is also notable that the enzyme is useful for the production of (S)-2-chloropropionate, which is used for the industrial production of aryloxyphenoxypropionic acid herbicides.

Acrylates↗