PubMed Health⌕ Search

Biomedical subjects

D Maes

Publications and source records attributed to D Maes.

At least 73 records · Page 4Linked to original sources
PubMed1998

Triose-phosphate isomerase (TIM) of the psychrophilic bacterium Vibrio marinus. Kinetic and structural properties.

The purification and characterization of triose-phosphate isomerase from the psychrophilic bacterium Vibrio marinus (vTIM) is described. Crystal structures of the vTIM-sulfate complex and the vTIM-2-phosphoglycolate complex (at a 2.7-A resolution) are also presented. The optimal growth temperature of Vibrio marinus is 15 degrees C. Stability studies show that vTIM is an unstable protein with a half-life of only 10 min at 25 degrees C. The vTIM sequence is most closely related to the sequence of Escherichia coli TIM (eTIM) (66% identity), and several unique structural features described for eTIM are also seen in vTIM, but eTIM is considerably more stable. The Td values of vTIM and eTIM, determined by calorimetric studies, are 41 and 54 degrees C, respectively. Amino acid sequence comparison reveals that vTIM has an alanine in loop 8 (at position 238), whereas all other TIM sequences known to date have a serine. The vTIM mutant A238S was produced and characterized. Compared with wild type, the catalytic efficiency of the A238S mutant is somewhat reduced, and its stability is considerably increased.

Amino Acid Sequence↗
PubMed1998

Protection against cigarette smoke-induced damage to intact transformed rabbit corneal cells by N-acetyl-L-cysteine.

In order to assess cigarette smoke-induced oxidative damage to intact cells, an assay was developed to measure cell detachment and protection. Due to the complex nature of cigarette smoke, which contains molecules that can interfere with conventional spectrophotometric and fluorometric biochemical assays, transformed rabbit corneal cells were radiolabeled with tritiated thymidine and then subjected to direct stream smoke. As a result, cell damage in response to the smoke from only two cigarettes could be measured in a time-dependent manner. When cells were prelabeled with N-acetyl-L-cysteine (NAC), a substrate for glutathione synthesis, a significant reduction in damage was measured. Additionally, when buthionine sulfoximine (BSO), an inhibitor of glutathione synthesis, was incubated with cells, a reduction in the effectiveness of NAC was observed, although NAC still retained some activity. Furthermore, vitamin E conferred no protection to cells in this system nor was NAC active in a separate assay that appears to favor peroxyl radical generation. From these results we conclude that cigarette smoke damage can easily be determined at the cellular level with this technique and that NAC acted to prevent this damage in two ways: first, as glutathione precursor and, secondly, as an antioxidant capable of scavenging non-peroxyl radicals.

Acetylcysteine↗
PubMed1998

The effect of vaccination against Mycoplasma hypopneumoniae in pig herds with a continuous production system.

An inactivated Mycoplasma hyopneumoniae vaccine was evaluated in five pig herds clinically infected with enzootic pneumonia and practising a continuous production system in the growing/finishing unit. In each herd, a vaccinated and control group of approximately 47 pigs each were individually monitored from birth until slaughter. Vaccinated pigs received the first dose at about 1 week of age and the second approximately 3 weeks later. During all production stages, an equal number of vaccinated and control pigs was present in the same pen. Both groups were compared with respect to zootechnical parameters (major variables) and by means of serological, pathological, and bacteriological parameters (ancillary variables). Daily weight gain was improved by 14 gr/day during the period from 8 days of age until slaughter (P = 0.0486) and by 25 gr/day during the growing/finishing period (P = 0.0067). Mortality rate, and the costs for curative medication were not significantly improved by vaccination. The results of the ancillary variables are presented and discussed.

Animals↗
PubMed1998

[Acoustic quantification of right ventricular dimensions and systolic function].

In view of the important prognostic significance of right ventricular systolic function, there have been many non-invasive studies of this subject. The majority of these studies have been limited by difficulties in modelisation of this geometrically complex cardiac chamber. Automatic border detection by acoustic quantification based on the back scatter of ultrasound provides a "direct" method of analysing right ventricular dimensions and functions. The authors undertook a prospective study of 34 patients to evaluate the reliability of this technique in measuring the surfaces and fractional shortening of the right ventricle. The feasibility was 92%. The correlation coefficients between the manual two-dimensional technique and automatic border detection were 0.81 for the end diastolic surface areas, 0.85 for the end systolic surface areas and 0.74 for the fractional shortening. Compared with the isotopic ejection fraction, the correlation coefficient was 0.73. The authors conclude that acoustic quantification is a feasible and reliable technique of measuring right ventricular dimensions and its contractile function.

Adult↗
PubMed1997

[Transthoracic echocardiography and diagnosis of acute pulmonary embolism. Change in the diagnostic valve with respect to thresholds of classification].

The diagnostic value of transthoracic echocardiography in acute pulmonary embolism is not well established. Although many parameters are abnormal, the thresholds used vary according to the authors, limiting the contribution of the investigation to the diagnosis. In a prospective study of 70 patients with suspected acute pulmonary embolism without previous cardio-respiratory disease, the authors tried to determine the diagnostic thresholds using discriminating linear analysis and ROC curves. Parameters easily recorded in an emergency were analysed: end diastolic ventricular dimensions, ratio of these diameters and maximal velocity of tricuspid regurgitant flow. Thirty-one patients had pulmonary embolism quantified by the Miller index (average: 16 +/- 7, range 2 to 28). Measurements of left ventricular dimension were disappointing (sensitivity: 0.52, specificity: 0.73 for a threshold value of 45 mm). The right ventricular dimension was a better predictive parameter (sensitivity: 0.70, specificity: 0.86 for a threshold value of 25 mm). However, the ratio of right to left ventricular dimension had a better diagnostic value (sensitivity: 0.85, specificity: 0.78 for a threshold value of 0.5). The best diagnostic parameter was the maximal velocity of tricuspid regurgitation (sensitivity: 0.93, specificity: 0.82 for a threshold value of 2.5 m/s). The authors conclude that the maximal velocity of tricuspid regurgitation with a threshold of 2.5 m/s and the ratio of the ventricular dimensions with a threshold value of 0.5 are valuable diagnostic indicators for acute pulmonary embolism.

Acute Disease↗
PubMed1997

Rheumatic manifestations of scurvy. A report of two cases.

Bleeding into the muscles and joints can be the presenting manifestation of scurvy, as illustrated by two case-reports. One patient presented with hemarthrosis of the tibiotalar joint due to an insufficiency fracture and was suspected to have scurvy based on the presence of purpura and hypertrophy of the gums with loss of teeth. In the other patient, multiple hematomas in the lower limbs were found at presentation and the presence of coiled hairs suggested the diagnosis. Both patients had completely eliminated fruit and vegetables from their diet. Low levels of ascorbic acid were found in serum and urine. A full recovery was achieved in both cases under ascorbic acid supplementation.

Adult↗
PubMed1996

Structure of chymopapain at 1.7 A resolution.

The X-ray structure of chymopapain, a cysteine proteinase isolated from the latex of the fruits of Carica papaya L., has been determined by molecular replacement methods and refined to a conventional R factor of 0.19 for all observed reflections in the range from 9.5 to 1.7 A resolution. The crystals used in this study contained a unique molecular species of chymopapain with two moles of thiomethyl attached to the two free cysteines per mole of enzyme. A comparison is made with the other known papaya proteinase X-ray structures: papain, caricain, and glycyl endopeptidase. Their backbone conformations are extremely similar except for two loop regions. Both regions are located at the surface of the protein and far away of the active site cleft. In each X-ray structure the same water network was found at the interface between the two domains of the enzyme. A close examination of the active site groove showed that the specificity restrictions dictated by the S2 subsite did not differ significantly among the four proteinases.

Amino Acid Sequence↗
PubMed1996

A structure of the complex between concanavalin A and methyl-3,6-di-O-(alpha-D-mannopyranosyl)-alpha-D-mannopyranoside reveals two binding modes.

The structure of concanavalin A in complex with the trimannoside methyl-3,6-di-O-(alpha-D-mannopyranosyl)-alpha-D-mannopyranoside has been determined in a novel space group. In three of the four subunits of the concanavalin A tetramer, the interactions between the protein and the bound saccharide are essentially identical to those reported previously by other authors (Naismith, J. H., and Field, R. A. (1996) J. Biol. Chem. 271, 972-976). In the fourth subunit, however, the alpha1-->3 linkage has a different conformation, resulting in a different part of the alpha1-->3-linked mannose interacting with essentially the same surface of the protein. Furthermore, significant differences are observed in the quaternary associations of the subunits compared with the saccharide-free structures and other carbohydrate complexes, suggesting that the concanavalin A tetramer is a rather flexible entity.

Concanavalin A↗
PubMed1996

H NMR study of the solution structure of Ac-AMP2, a sugar binding antimicrobial protein isolated from Amaranthus caudatus.

The conformation in water of antimicrobial protein 2 from Amaranthus caudatus (Ac-AMP2) was determined using 1H NMR, DIANA and restrained molecular modeling. Ac-AMP2 is a 30 amino acid residue, lectin-like protein that specifically binds to chitin, a polymer of beta-1,4-N-acetyl-D-glucosamine. After sequence specific resonance assignments, a total of 198 distance restraints were collected from 2D NOESY buildup spectra at 500 MHz at pH 2, supplemented by a 2D NOESY spectrum at 600 MHz. The location of the three previously unassigned disulfide bridges was determined from preliminary DIANA structures, using a statistical analysis of intercystinyl distances. The solution structure of Ac-AMP2 is presented as a set of 26 DIANA structures, further refined by restrained molecular dynamics using a simulated annealing protocol in the AMBER force field, with a backbone r.m.s.d. for the well defined Glu3-Cys28 segment of 0.69(+/-0.12) angstroms. The main structural element is an antiparallel beta-sheet from Met13 to Lys23 including a betaI-turn over Gln17-Phel8 with a beta bulge at Gly19. In addition, a beta'I turn over Arg6-Gly7, a beta'III turn over Ser11-Gly12 and a helical turn from Gly24 to Cys28 are identified. This structure is very similar to the equivalent regions of the X-ray structure of wheat germ agglutinin and the NMR structure of hevein.

Amino Acid Sequence↗
PubMed1996

Enzootic pneumonia in pigs.

This article reviews current knowledge concerning enzootic pneumonia. Enzootic pneumonia, caused by Mycoplasma hyopneumoniae and exacerbated by secondary invaders, occurs worldwide and has been known for many years. The organism, with its typical characteristics, invades the respiratory tract in several successive steps. Clinical symptoms and lesion development are the result of the pathogenic capacity of Mycoplasma hyopneumoniae and the defence reactions in the lung. The economic relevance of pneumonia is influenced to a large extent by common secondary infections which follow an initial M. hyopneumoniae infection. Different tests for the diagnosis of pneumonia in individual pigs and in groups are available. Treatment and control is not simple since enzootic pneumonia is a multi-factorial disease. Some epidemiological aspects and the most important measures for prevention of the disease are described.

Animals↗
PubMed1996

Use of transthoracic Doppler echocardiography combined with clinical and electrocardiographic data to predict acute pulmonary embolism.

Transthoracic echocardiography and continuous wave Doppler were prospectively performed in 132 out-patients with suspicion of pulmonary embolism, and who had no previous history of severe cardiac or pulmonary disease. Bedside echocardiography determined diagnosis other than pulmonary embolism in 55 patients. Further study was completed in 70 patients; pulmonary embolism was found in 31 and excluded in 39. Significant differences were found as regards right ventricular diameter (27 +/- 8 vs 22 +/- 5 mm, P < 0.001), left ventricular diameter (41 +/- 9 vs 49 +/- 7 mm, P < 0.001), right over left ventricular diameter ratio (0.67 +/- 0.23 vs 0.43 +/- 0.15, P < 0.0001), tricuspid regurgitant flow peak velocity (2.9 +/- 0.4 vs 2.4 +/- 0.7 m.s-1, P < 0.0001), and abnormal septum motion (12 vs 4, P < 0.01). Multivariate analysis of echocardiographic data included a tricuspid regurgitant flow peak velocity greater than 2.5 m.s-1 and a right over left ventricular diameter ratio greater than 0.5 in a logistic model (sensitivity 93%, specificity 81%). The combination of echocardiographic and non-echocardiographic data included the two previous echocardiographic variables, together with signs of deep vein thrombosis, a deep S wave in lead D1, and a Q wave in lead D3 on the electrocardiogram in a logistic model (sensitivity 96%, specificity 83%). It can be concluded that emergency echocardiography, alone or combined with clinical examination and electrocardiogram, satisfactorily predicts acute pulmonary embolism.

Acute Disease↗
PubMed1996

[Value of transesophageal echocardiography in post-infarction septal ruptures].

The role of transoesophageal echocardiography in the diagnosis of ventricular septal defect in the acute stage of myocardial infarction, was evaluated in 15 consecutive patients (10 men and 5 women) with a mean age of 72 years in the period between June 1991 and April 1995. The patients had 11 anterior infarcts and 4 inferior infarcts with extension to the right ventricle. One patient was in Killips class I,7 patients in class II, 2 in class III and 5 in class IV. Only 8 of the 15 septal ruptures could be visualised directly by conventional transthoracic echocardiography, though all 15 were suspected from continuous Doppler and colour Doppler analysis. Transoesophageal echocardiography was successfully performed in 14 of the 15 patients with a monoplane probe in 11 cases and a multiplane probe in 3 cases. The average duration of the procedure was 12 minutes and clinical and haemodynamic tolerance was good. Ventricular septal defect was directly visualised in all cases in the short axis transgastric view and in 7 cases in transoesophageal views. Transoesophageal echocardiography was concordant with peroperative findings with regards to the site of ventricular septal defect (8 apical, 5 postero-basal and 1 median), their type (6 punched-out defects, 5 fissures, and 3 perforated aneurysms), their size (average 9.3 mm), their number with 5 multiple defects, and associated lesions (4 right ventricular extensions, 4 hemopericardiums and 1 free wall fissure). Transoesophageal echocardiography completes traditional transthoracic echocardiographic examination in the diagnosis of post-infarction ventricular septal defect. It is well tolerated and, in the authors' experience, allows limitation of invasive procedures to coronary angiography alone.

Aged↗
PubMed1996

[Estimation of left ventricular volumes and ejection fraction with acoustic quantification in myocardial infarction. Comparison with echocardiographic, angiographic and scintigraphic data].

The object of this study was to assess the reliability of measurements of left ventricular volumes and ejection fraction by acoustic quantification by the method of summation of discs in acute myocardial infarction. Thirty-two patients with an average age of 55.9 +/- 12 years were studied prospectively on average 6 +/- 2 days after the onset of myocardial infarction. Within 48 hours, the patients underwent TM echocardiography (Teichholz's method) two-dimensional echocardiography (Simpson's method on freeze frames and acoustic quantification) before left ventricular angiography and isotopic ventriculography, considered as the reference methods for comparing left ventricular volumes and ejection fractions. The data displayed in real time by acoustic quantification correlated well with the results of left ventricular angiography (r = 0.77; p = 0.0001) and moderately underestimated (+4.1 +/- 11.9%) the ejection fraction, but were relatively disappointing for estimating volumes. When compared with isotopic ejection fraction, the correlation coefficient was r = 0.71 (p = 0.0004) and the values were overestimated. In this study, acoustic quantification was the most reliable echocardiographic method of assessing the left ventricular ejection fraction with reference to contrast angiography (Teichholz: r = 0.56; p = 0.0014; Simpson: r = 0.76; p = 0.001). The authors conclude that assessing the left ventricular ejection fraction with acoustic quantification is reliable in acute myocardial infarction. However, the method is not very accurate in measuring end systolic and end diastolic volumes.

Acoustics↗
PubMed1996

[Ventricular late potentials and sleep apnea syndromes].

This prospective study in 37 patients evaluated the prevalence of ventricular late potentials in sleep apnea syndrome, a condition associated with an increased risk of ventricular rhythm disorders and sudden death. A comparative analysis was conducted among a group of patients considered free of coronary heart disease and admitted for suspected sleep apnea syndrome based on clinical symptoms and simple blood gas measurements. The prevalence of ventricular late potentials was 56% in the subgroup with and 14% in the subgroup without polygraphy evidence of apnea (F < 0.01). The analysis of clinical, respiratory, and echocardiographic findings in the apneic subgroup failed to detect any factors associated with the presence of ventricular late potentials. Only long-term follow-up studies involving invasive heart rhythm testing could define the prognostic significance of ventricular late potentials in sleep apnea syndrome. However, our data demonstrate that there is an association between ventricular late potentials and sleep apnea syndrome.

Adult↗
PubMed1995

Structure of the crystalline complex of deoxycytidylyl-3',5'-guanosine (3',5'-dCpdG) cocrystallized with ribonuclease at 1.9 A resolution.

The X-ray structure of bovine ribonuclease A cocrystallized with the dinucleotide deoxycytidylyl-3',5'-guanosine has been determined at 1.9 A resolution and refined by restrained least squares to R = 0.218 for 7807 reflections. The structure established that the recently observed retrobound mode of attachment of substrate analogues cytidylyl-2',5'-guanosine and deoxycytidylyl-3',5'-guanosine found in soaked RNase A crystals is also present in the cocrystallized complex. Retrobinding is thus unlikely to be the result of restrictions imposed by the crystalline environment as the ligands soak into the lattice but rather a phenomenon specific to small nucleotides containing guanine.

Journal Article↗