PubMed Health⌕ Search

Biomedical subjects

D Maes

Publications and source records attributed to D Maes.

At least 91 records · Page 5Linked to original sources
PubMed1995

1H NMR study of the interaction of N,N',N"-triacetyl chitotriose with Ac-AMP2, a sugar binding antimicrobial protein isolated from Amaranthus caudatus.

The interaction between Ac-AMP2, a lectin-like small protein with antimicrobial and antifungal activity isolated from Amaranthus caudatus, and N,N',N"-triacetyl chitotriose was studied using 1H NMR spectroscopy. Changes in chemical shift and line width upon increasing concentration of N,N',N"-triacetyl chitotriose to Ac-AMP2 solutions at pH 6.9 and 2.4 were used to determine the interaction site and the association constant Ka. The most pronounced shifts occur mainly in the C-terminal half of the sequence. They involve the aromatic residues Phe18, Tyr20 and Tyr27 together with their surrounding residues, as well as the N-terminal Val-Gly-Glu segment. Several NOEs between Ac-AMP2 and the N,N',N"-triacetyl chitotriose resonances are reported.

Amino Acid Sequence↗
PubMed1995

Diagnostic accuracy of echocardiography-Doppler in acute pulmonary embolism.

We studied prospective recording of clinical, electrocardiographic, Doppler and echographic parameters in 32 patients with proven pulmonary embolism, matched with 32 patients with clinically suspected pulmonary embolism and normal perfusion scan or angiography. Thirty-seven per cent of cases and 16% of control subjects had clinical signs of right ventricular overload; S1-Q3-T3 ECG pattern was found in 11 cases and one control. Other clinical and ECG parameters did not reach significant difference. Echographic septum motion was abnormal in 42% of cases and 9% of controls (P < 0.05), end-diastolic right ventricular diameter was > 25 mm in 67% of cases and 11% of controls, ratio of end-diastolic right over left ventricular diameters increased over 0.6 in 67% of cases and 11% of controls, while Doppler examination found tricuspid regurgitant peak flow velocity > 2.5 m/s in 84% of cases vs. 10% of controls. According to these parameters, Doppler-echocardiography was normal in 6% of cases and 87% of control subjects (P < 0.001 for each). In suspected pulmonary embolism, our study shows that Doppler-echocardiography may be both sensitive and specific in emergency conditions and help the decision making for further invasive investigations.

Acute Disease↗
PubMed1995

Coronary angioplasty of bifurcational lesions with the protecting branch technique using 6 French guiding catheter.

The use of 6 French guiding catheters is still usually limited to elective percutaneous transluminal coronary angioplasty. We describe our preliminary experience with this guiding size to perform a double guide wire procedure for angioplasty or coronary bifurcation lesions, to protect (n = 5) and/or to sequentially dilate (n = 9) a major side branch. Technical success was 12/14 (86%), angiographic success 13/14 (93%), and in-hospital outcome was event free in all patients. Thus, 6 French guiding size is both safe and effective for the majority of coronary bifurcation angioplasty.

Angioplasty, Balloon, Coronary↗
PubMed1995

A comparative structural study on the steroids [1,2,5]oxadiazolo[3', 4':3,4]-5 alpha-pregn-16-en-20-one oxime (HS998), [1,2,5]oxadiazolo[3, 4':3,4]-5 beta-pregn-16-en-20-one (HS973) by NMR, molecular modeling, and X-ray investigations.

The molecular structure of the steroids [1,2,5]oxadiazolo[3', 4':3,4]-5 alpha-pregn-16-en-20-one oxime, [1,2,5]oxadiazolo[3',4':3, 4':3,4]-5 alpha-pregn-16-en-20-one and [1,2,5]oxadiazole]3',4':3,4]-5 beta-pregn-16-en-20-one has been determined. The proton-proton distances in the solid state from previous crystallographic studies are compared with the corresponding distances from novel and previous solution NMR as well as from novel in vacuo modeling studies.

Crystallization↗
PubMed1995

[Transesophageal echocardiographic diagnosis of left ventricular parietal rupture, a complication of myocardial infarction].

The authors report the case of postero-lateral myocardial infarction complicated by free wall rupture at the 48th hour. The diagnosis was suspected clinically and transoesophageal echocardiography showed the appearance of pericardial effusion in a patient difficult to examine by conventional echocardiography. Transoesophageal echocardiography was performed and well tolerated. The transgastric view showed a thrombus adjacent to a thinned and lacerated postero-lateral wall. The clinical outcome was favourable after surgical repair.

Echocardiography, Transesophageal↗
PubMed1995

[Evaluation of the systematic use of wide lumen 6 French guiding catheters in conventional coronary angioplasty].

The aim of this study was to evaluate the results of systematic use of 6 French guiding catheters in conventional balloon coronary angioplasty without any restriction of indications apart from coronary lesions necessitating other techniques such as atherectomy. Therefore, after a learning period, 200 consecutive procedures performed between November 1993 and June 1994 for the treatment of 234 lesions were analysed prospectively. Fifty-one patients had stable and 70 unstable angina. In 79 cases, the angioplasty was performed on the culprit lesion of a myocardial infarction. An angiographic success was obtained for 206 lesions or 88% of cases which increased to 95% after exclusion of attempted recanalisation. There were 3 cases of damage to the ostium and 7 patients underwent implantation of a stent with the same catheter for occlusive or threatening dissection. There were 10 ischaemic complications (5%) (7 non-Q wave infarctions, 2 Q wave infarctions, 1 aorto-coronary bypass, no deaths) and 8 local complications at the site of arterial catheterisation during the hospital period. These results demonstrate the feasibility of coronary angioplasty with wide lumen 6 French guiding catheters and show that they amy be used in first intention for all conventional balloon angioplasty procedures.

Adult↗
PubMed1995

[Pulmonary embolism and thrombi of the right heart].

In general, there are two types of right heart thrombi diagnosed by echocardiography: mobile and non-mobile thrombi, more often located in the atrium than in the ventricle and a potential source of pulmonary embolism. However, they differ in several points: clinical context, clinical and echocardiographic presentations, embolic potential, prognosis and treatment. The result of peripheral venous thrombosis, mobile thrombus it is usually diagnosed during echocardiographic investigation of pulmonary embolism. The appearances are often that of serpentine thrombus floating in the right heart chambers associated with signs of acute cor pulmonale. It is a marker of imminent and often fatal embolism as it completes a previous and usually severe pulmonary embolism; the mortality is over 40%. It is a contra-indication for pulmonary angiography because of the risk of embolism and a therapeutic emergency. Some groups advocate surgical embolectomy and others thrombolysis. Its precise frequency in the acute stage of pulmonary embolism and its treatment remain to be determined by a prospective, multicentre clinical trial. The adherent non-mobile thrombus is usually implanted on the free wall of the right atrium or the interatrial septum. Its formation, in situ, is due to stasis secondary to decompensated congenital or acquired cardiac disease or to the presence of an intracardiac foreign body such as a pacing wire. It is less likely to cause pulmonary embolism. It decreases or disappears with anticoagulant therapy and the outcome is usually good. The differential diagnosis between a mobile thrombus and a Chiari network, or between an adherent thrombus and a vegetation on a intracardiac pacing wire may be difficult and requires transoesophageal echocardiography. The investigation of pulmonary embolism requires systematic echocardiography, one of the objectives of which is to search for right sided thrombi.

Anticoagulants↗
PubMed1994

The structures of RNase A complexed with 3'-CMP and d(CpA): active site conformation and conserved water molecules.

The interactions of RNase A with cytidine 3'-monophosphate (3'-CMP) and deoxycytidyl-3',5'-deoxyadenosine (d(CpA)) were analyzed by X-ray crystallography. The 3'-CMP complex and the native structure were determined from trigonal crystals, and the d(CpA) complex from monoclinic crystals. The differences between the overall structures are concentrated in loop regions and are relatively small. The protein-inhibitor contacts are interpreted in terms of the catalytic mechanism. The general base His 12 interacts with the 2' oxygen, as does the electrostatic catalyst Lys 41. The general acid His 119 has 2 conformations (A and B) in the native structure and is found in, respectively, the A and the B conformation in the d(CpA) and the 3'-CMP complex. From the present structures and from a comparison with RNase T1, we propose that His 119 is active in the A conformation. The structure of the d(CpA) complex permits a detailed analysis of the downstream binding site, which includes His 119 and Asn 71. The comparison of the present RNase A structures with an inhibitor complex of RNase T1 shows that there are important similarities in the active sites of these 2 enzymes, despite the absence of any sequence homology. The water molecules were analyzed in order to identify conserved water sites. Seventeen water sites were found to be conserved in RNase A structures from 5 different space groups. It is proposed that 7 of those water molecules play a role in the binding of the N-terminal helix to the rest of the protein and in the stabilization of the active site.

Binding Sites↗
PubMed1993

Structure of the crystalline complex of cytidylic acid (2'-CMP) with ribonuclease at 1.6 A resolution. Conservation of solvent sites in RNase-A high-resolution structures.

The X-ray structure of the inhibitor complex of bovine ribonuclease A with cytidylic acid (2'-CMP) has been determined at 1.6 A resolution and refined by restrained least squares to R = 0.17 for 11 945 reflections. Binding of the inhibitor molecule to the protein is confirmed to be in the productive mode associated with enzyme activity. A study of conserved solvent sites amongst high-resolution structures in the same crystal form reveals a stabilizing water cluster between the N and C termini.

Journal Article↗
PubMed1993

Crystal structure determination and refinement at 2.3-A resolution of the lentil lectin.

We report on the X-ray structure determination of the orthorhombic crystal form of lentil lectin by molecular replacement using the pea lectin coordinates as a starting model. The structure was refined at 2.3-A resolution with a combination of molecular dynamics refinement and classical restrained least-squares refinement. The final R value for all data Fo > 1 sigma (Fo) between 7.0- and 2.3-A resolution is 0.164%, and deviations from ideal bond distances are 0.014 A. The C-terminus of the beta-chain proved to be 23 amino acids longer than found in previous studies. This together with several inconsistencies between the previously determined amino acid sequence and the observed electron density forced a redetermination of the amino acid sequence of the protein. The overall structure is very similar to that of pea lectin and isolectin I of Lathyrus ochrus, the most prominent deviations being confined to loop regions and the regions of intermolecular contact. The largest difference between the pea and lentil lectin monomers is situated in the loop region of amino acids 73-79 of the beta chain. There are no significant differences between the two crystallographic independent lentil lectin monomers in the asymmetric unit. The model includes 104 well-defined water molecules, of which a significant number have a counterpart in the pea lectin structure. As for the other legume lectins, each lentil lectin monomer contains one calcium ion in a highly conserved environment. On the contrary, the manganese binding sites are distorted with respect to the pea lectin and concanavalin A structures. The Asp beta 121 side chain apparently does not ligate the Mn2+ ion. This difference is consistent in both lentil lectin monomers and agrees with earlier solution studies. Possible implications for oligosaccharide binding are discussed.

Amino Acid Sequence↗
PubMed1993

[Value of transesophageal echography in the detection of left intraventricular masses. Apropos of a case of apical thrombus].

The authors report a case of left intraventricular thrombus investigated by two-dimensional transesophageal echocardiography (TEE). Three longitudinal views obtained by rotation, left lateral inclination and by advancing the probe, enabled the precise evaluation of a mass situated at the apex of the left ventricle, together with ventricular morphology and kinetics. Two-dimensional TEE is electively indicated for confirmation of the diagnosis of left intraventricular apical masses, in particular in hypoechogenic patients and to guide possible surgery. The two-plane probe provides a certain number of sections which remain relatively limited but this problem is resolved with the development of multidimensional probes.

Echocardiography↗
PubMed1992

Two crystal forms of the lentil lectin diffract to high resolution.

The legume lectins are an important class of polysaccharide-binding proteins with a wide range of biochemical and immunological applications. Two high-resolution crystal forms are obtained for the lentil (Lens culinaris) lectin: a monoclinic P21 and an orthorhombic P212121. The unit cell dimensions for the monoclinic form are a = 58.0 A, b = 56.0 A, c = 82.1 A, beta = 104.4 degrees, while for the orthorhombic form a = 56.4 A, b = 74.6 A, c = 124.9 A. The asymmetric unit contains one dimer in both cases. The crystals diffract to 1.7 A resolution using synchrotron radiation. Preliminary data have been collected to 2.3 A on both crystal forms using a conventional X-ray source.

Crystallography↗
PubMed1990

An in vitro model to test relative antioxidant potential: ultraviolet-induced lipid peroxidation in liposomes.

Since antioxidants have been shown to play a major role in preventing some of the effects of aging and photoaging in skin, it is important to study this phenomenon in a controlled manner. This was accomplished by developing a simple and reliable in vitro technique to assay antioxidant efficacy. Inhibition of peroxidation by antioxidants was used as a measure of relative antioxidant potential. Liposomes, high in polyunsaturated fatty acids (PUFA), were dispersed in buffer and irradiated with ultraviolet (UV) light. Irradiated liposomes exhibited a significantly higher amount of hydroperoxides than liposomes containing antioxidants in a dose- and concentration-dependent manner. Lipid peroxidation was determined spectrophotometrically by an increase in thiobarbituric acid reacting substances. To further substantiate the production of lipid peroxides, gas chromatography was used to measure a decrease in PUFA substrate. In order of decreasing antioxidant effectiveness, the following results were found among lipophilic antioxidants: BHA greater than catechin greater than BHT greater than alpha-tocopherol greater than chlorogenic acid. Among hydrophilic antioxidants, ascorbic acid and dithiothreitol were effective while glutathione was ineffective. In addition, ascorbic acid was observed to act synergistically with alpha-tocopherol, which is in agreement with other published reports on the interaction of these two antioxidants. Although peroxyl radical scavengers seem to be at a selective advantage in this liposomal/UV system, these results demonstrate the validity of this technique as an assay for measuring an antioxidant's potential to inhibit UV-induced peroxidation.

Antioxidants↗
PubMed1990

Clean intermittent self-catheterization: a 12-year followup.

We studied retrospectively 75 patients who performed clean intermittent self-catheterization for a mean of 7 years (maximum 12 years). Most of the patients had neuropathic bladder dysfunction and 92% were continent. Chronic or recurrent urinary tract infections were present in 42% of the patients. Although the upper urinary tract was well preserved in the majority of the patients regular screening for silent hydronephrosis and/or asymptomatic reflux proved to be necessary. Complications occurred in 15 patients, with a urethral pathological condition being the most frequent complication in our male patients during followup.

Adolescent↗
PubMed1988

Correlation between history and urodynamics in neurologically normal incontinent women.

We compared the history of 100 consecutive women complaining of incontinence with their urodynamic findings. The real urodynamic situation proved unpredictable on the basis of the medical history. A good correlation between history and urodynamics was found in 80% of the women complaining of stress incontinence. The importance of a uroflowmetry to screen voiding difficulties in all patients is demonstrated. To get to a proper diagnosis in most women complaining of incontinence, technical urodynamic investigation seems mandatory.

Female↗