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Biomedical subjects

A Segers

Publications and source records attributed to A Segers.

At least 19 recordsLinked to original sources
PubMed2004

Development of a patient-based grading scale for PedMIDAS.

The objective was to develop and validate a patient-based grading scale for PedMIDAS. PedMIDAS was administered to 329 children, who rated their overall disability based on the adult MIDAS grades. This patient-based rating and PedMIDAS scores were compared to develop the grading scale. Headache disability was rated little to none, 49.5%; mild, 26.7%; moderate, 15.8%; and severe, 7.9%, with PedMIDAS raw scores of 4.9 +/- 6.3, 17.8 +/- 14.9, 40.6 +/- 34.2, and 91.4 +/- 69.8. Convergence of these results yielded an empirically derived grading system: Grade I, 0-10; II, 11-30; III, 31-50 and IV, > 50. Higher grades corresponded to an increased need for prophylactic treatment. A patient-based grading scale further increases the utility of PedMIDAS in assessing migraine disability in children, so that it can be widely used in routine clinical evaluation and management.

Adolescent↗
PubMed1994

Homo- and heteronuclear two-dimensional NMR studies of the globular domain of histone H1: full assignment, tertiary structure, and comparison with the globular domain of histone H5.

The globular domain of chicken histone H1 (GH1) has been studied by 1H homonuclear and 1H-15N heteronuclear 2D NMR spectroscopy. After the full assignment of the proton and 15N resonances, the tertiary structure of GH1 was determined by an iterative procedure using distance geometry and restrained simulated annealing. The secondary structure elements of GH1, three helices (S5-A16, S24-A34, N42-K56) followed by a beta-hairpin (L59-L73), are folded in a manner very similar to the corresponding parts of the globular domain of chicken histone H5 (GH5) [Clore et al. (1987) EMBO J. 6, 1833-1842; Ramakrishnan et al. (1993) Nature 362, 219-223]. However, subtle differences are detected between the two structures and between the electrostatic potentials surrounding the molecules. The most important differences are located in the loop between the second and third helices, a region that could be responsible for the different affinity for DNA. The most positively charged regions are not found in exactly the same position in GH1 and GH5. Nevertheless, their location seems to agree with the model where nucleosome binding takes place through contact points located at one DNA terminus and close to the dyad axis of the nucleosome [Schwabe & Travers (1993) Curr. Biol. 3, 628-630].

Amino Acid Sequence↗
PubMed1993

Homo- and heteronuclear two-dimensional NMR studies of the globular domain of histone H1: sequential assignment and secondary structure.

A recombinant 75 amino acid polypeptide corresponding to the globular domain of the chicken histone H1 (GH1) has been studied by 1H homonuclear and 1H-15N heteronuclear 2D NMR spectroscopy. Sequential assignment of the backbone and beta-proton resonances has enabled us to determine the secondary structure of GH1. It was found to consist of three helical regions (T7-S17, L25-Y37, E40-K56) and probably a beta-hairpin (L59-L73). This structure is similar to the structure of the globular domain of histone H5 (GH5) obtained both by NMR spectroscopy [Zarbock et al. (1986) Proc. Natl. Acad. Sci. U.S.A. 83, 7628-7632; Clore et al. (1987) EMBO J. 6, 1833-1842] and by X-ray crystallography [Ramakrishnan et al. (1993) Nature 362, 219-223]. The beta-hairpin as suggested for GH1 is also present in the X-ray structure of GH5 but has not been reported for the NMR structure of GH5.

Amino Acid Sequence↗
PubMed1992

Involvement of 19q13 in follicular thyroid adenoma.

Cytogenetic investigation of a follicular thyroid adenoma from a 31-year-old woman showed a t(16;19)(q12;q13), as the sole chromosome abnormality. As five more cases with 19q13 involvement have been described, we suggest that the terminal region of the long arm of chromosome 19 is important for the development of follicular thyroid adenoma.

Adenoma↗
PubMed1992

[Myotomy of the cricopharyngeal muscle].

Eleven patients who underwent cricopharyngeal myotomy from 1980 to 1990 at the Department of ENT, Head and Neck Surgery, KUL are reviewed. This procedure has been performed for swallowing and/or aspiration disorders due to dysfunction of varied etiology of m. cricopharyngeus. Our results indicate that only patients with a satisfactory pharyngeal motion and coordination and no cricopharyngeal relaxation are proven candidates for cricopharyngeal myotomy. Patients with Zenker's diverticulum were not taken into account. Nine out of 11 patients improved after cricopharyngeal myotomy. Careful interpretation of cineradiographic examination allows refinement of case selection.

Adult↗
PubMed1991

A model for histone H5-DNA interaction: simultaneous minor and major groove binding.

Using the tertiary structure of the globular domain of H5 (GH5) and based on an alternative sequence homology between GH5 and DNA-binding proteins containing the helix-turn-helix motif, a model for H5-DNA interaction is proposed. From molecular graphics it follows that helix II recognizes the major groove of the DNA, as does the second helix of the helix-turn-helix motif, while helix III makes minor groove contacts, in agreement with the hypothesis of Turnell et al. (FEBS letters 232, 263-268). In the resulting model GH5 makes contact with a full turn of DNA.

Amino Acid Sequence↗
PubMed1991

The interaction of histone H5 and its globular domain with core particles, depleted chromatosomes, polynucleosomes, and a DNA decamer.

Certain features of linker histone behavior were analyzed using a precipitation and a nitrocellulose filter binding assay. Chromatosomes, depleted of the linker histones, present one unique binding site to the globular domain of histone H5 (GH5) which involves the two 10-base pair DNA ends of the chromatosome. Additional binding to lower affinity sites is intrinsically different and results in aggregation as does all binding to core particles. These findings, as well as the binding study on a synthetic DNA decamer, lend support to earlier hypotheses of more than one DNA binding site on the globular domain. Our studies provide a deeper insight into the long standing question of H5/nucleosome stoichiometry. A salt dependence analysis of GH5 binding to H5-depleted chromatosomes indicates that GH5 displaces a number of ions similar to the total H1 linker histone, suggesting a delocalized binding of the carboxyl- and amino-terminal tails.

Animals↗
PubMed1991

Epiglottoplasty for reconstruction of posttraumatic laryngeal stenosis.

Laryngeal stenosis secondary to blunt laryngeal trauma is mostly localized at the supraglottic and glottic levels. The epiglottis is ideally suited to reconstruct the defect after excision of supraglottic and glottic scar tissue and anterior thyroid cartilage. It is the conclusion of the authors that epiglottic reconstruction is an effective procedure for repair of laryngeal stenosis at the supracricoid level. Two case reports are given.

Adult↗
PubMed1990

[Radiotherapy as primary treatment for chemodectoma?].

Chemodectomas are slowly growing tumours originating in the chemoreceptor bodies. The diagnosis is based on typical clinical symptoms and radiological investigation. CT scanning with contrast enhancement permits to establish diagnosis in most cases and gives a correct idea of tumour size, tumour extension, displacement of arteries and bone destruction. Small tympanic chemodectomas are successfully managed by surgery, without causing additional cranial nerve palsies. Surgery of larger lesions is frequently followed by a high percentage of local recurrence (greater than 50%) and important morbidity (neurologic sequelae). Our present series confirms that these tumours can successfully be treated by radiotherapy. Persisting local control rates can be obtained in more than 90% of cases with moderate doses (45-50 Gy in 5 weeks) of carefully planned radiotherapy.

Adult↗
PubMed1984

Cardiovascular effects of sulmazol administered intravenously to patients with severe heart failure.

Ten patients with severe heart failure (NYHA class IV) received sulmazol intravenously under haemodynamic and electrocardiographic surveillance. All patients were on maintenance doses of digitalis and diuretics. At 30 min intervals we increased the infusion rate of sulmazol from 1 to 2, 4, 6, and 8 mg min-1, to a total of 630 mg of sulmazol administered over 150 min. Statistically significant changes (P less than 0.001) were found for heart rate (from 97 to 103 min-1); right atrial pressure (from 9.5 to 1.5 mmHg); pulmonary artery diastolic pressure (from 25.0 to 9.0 mmHg); pulmonary capillary wedge pressure (from 22.0 to 9.0 mmHg); aortic diastolic pressure (from 62.5 to 52.5 mmHg); pulmonary artery oxygen saturation (from 53.0 to 68.5%); cardiac output (from 2.83 to 4.38 l min-1), and for indices derived from these measurements. No correlation was found between the improvement in cardiac performance and sulmazol plasma concentrations. Haemodynamic improvement persisted for more than 7.5 h after cessation of sulmazol administration. Renal function was measured before and after sulmazol administration; creatinine clearance (from 47.5 to 52.0 ml min-1) and p-amino hippuric acid clearance (from 146 to 125 ml min-1) were unchanged. Side-effects included yellow-colored vision, ventricular extrasystoles, and possibly sulmazol-induced liver function disturbances. Even in severe heart failure sulmazol improved cardiac performance in patients who were treated with the maximum tolerated dose of digoxin.

Acute Disease↗
PubMed1984

Serial electrophysiologic studies after single chamber atrial pacemaker implantation in patients with symptomatic sinus node dysfunction.

After single chamber atrial pacemaker implantation, serial electrophysiologic studies were performed noninvasively at intervals of 3 months over a total period of 3 years in 24 patients with symptomatic sinus node dysfunction. All patients underwent invasive electrophysiologic studies before pacemaker implantation and demonstrated intact anterograde AV conduction. Patients were divided into 2 groups: group I did not require antiarrhythmic drugs during follow-up whereas group 2 received antiarrhythmic drugs. In group I (11 patients) the atrial paced heart rate producing AV Wenckebach phenomenon (AVWHR) remained stable during a mean follow-up of 22 +/- 10 months; with a variability not exceeding 10 beats min-1 with respect to the initial AVWHR obtained during preoperative electrophysiologic study. In group 2 (13 patients) with a mean follow-up of 15 +/- 8 months a mean decrease of AVWHR of 19.2 +/- 17.5 beats min-1 was present between AVWHR before and 3 months after initiation of oral antiarrhythmic drugs (P less than 0.01). During chronic (greater than 3 months) antiarrhythmic drug therapy the variability of the AVWHR never exceeded 10 beats min-1 with respect to the AVWHR obtained 3 months after the initiation of oral drug therapy. Deterioration of anterograde AV conduction during long-term follow-up of patients with symptomatic sinus node dysfunction and intact anterograde AV conduction at the time of pacemaker implantation is a consequence of orally taken antiarrhythmic drugs, rather than a consequence of degeneration of the AV conducting system.

Aged↗
PubMed1977

Regional cerebral blood flow in children. A rheoencephalographic study of the modifications induced by reading.

Cerebral impedance changes (F changes) indicating cerebral blood flow were studied in 17 children aged 6-11 years and in 10 normal adults. At rest, large values were found in children, who never exhibited the 'hyperfrontality' pattern of the adults. Reading induced an F increase in both the dominant and non-dominant hemispheres, in contrast with a larger increase in the dominant hemisphere in adults. A spatial test was designed in adults which triggered a larger increase in the non-dominant hemisphere.

Adult↗
PubMed1975

Value of brain scanning in pediatric subdural collections.

Piepsz, A., Bormans, J., Segers, A., Noterman, J. and Decostre, P. (Departments of Paediatrics, Radioisotopes and Neurosurgery, University Hospital, Brussels, Belgium). Value of brain scanning in pediatric subdural collections. Acta Paediatr Scand, 64:2, 1965. Eighteen children with subdural collections were submitted to brain scintigraphy. By this method, idopathic and post-traumatic hematomas were detected in 40% of the cases, and subdural effusions in 70% of the cases. No false-negative results were noted in the 3 cases of empyema. Several false-positive images were recorded, most of them following purulent meningitis, without any satisfactory explanation. Neither the technique of scintigraphy used in the department, the dimensions of the skull, the age of hematoma, nor the presence of membranes seemed to affect the accuracy of the method. Compared with the other easily performed examinations (eye fundus, EEG, Echo), scintigraphy still remains important in the diagnosis of subdural collections in children.

Adolescent↗