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Biomedical subjects

E Van de Velde

Publications and source records attributed to E Van de Velde.

At least 19 recordsLinked to original sources
PubMed2003

The prognostic significance of changes in X-ray attenuation on CT in established cerebral infarcts.

BACKGROUND: X-ray hypoattenuation on computed tomography (CT) reflects the severity of ischaemic damage after stroke. However, the clinical syndrome and the effect of time influence the visibility of infarcts. This prospective study analyses whether the degree of hypoattenuation on CT at two time intervals after stroke has a predictive value for the clinical outcome. METHODS: 220 consecutive stroke patients were admitted within 24 h after onset with symptoms lasting more than 24 h. The study was restricted to 150 patients displaying an anterior circulation infarct or syndrome. All patients had CT scans without contrast enhancement on day 3 (+/-8 h) and day 10 (+/-8 h) after stroke onset. The degree of X-ray attenuation expressed in Hounsfield units was determined in the centre of the infarct area and compared to that in the corresponding zone of the contralateral hemisphere. The patients were divided into four groups according to their degree of disability at 3 months on the modified Rankin scale as follows: R 0-1, R 2-3, R 4-5 and R 6. RESULTS: Patients in groups R 4-5 and R 6 had the most severe impairment on admission. The average decrease of X-ray attenuation on CT on day 3 was less in patients in group R 0-1, but was not different between the three other groups, while it was significantly correlated with the severity of the disability on day 10. CT X-ray attenuation increased between days 3 and 10 in group R 0-1, was unchanged in group R 2-3 and further decreased in groups R 4-5 and R 6. CONCLUSION: The degree of X-ray attenuation on CT on day 3 allows us to distinguish those patients who will recover more or less completely from those with definite disability, while the CT findings on day 10 allow a more precise prediction of outcome. Increase of X-ray attenuation on day 10 is known as the fogging effect and appears to be a favourable prognostic factor. Fogging is generally considered to be due to macrophage invasion and proliferation of capillaries within the infarct area, but probably also represents partial restoration of some viable tissue.

Aged↗
PubMed2000

Effect of maturation and aging on beta-adrenergic signal transduction in rat kidney and liver.

The characteristics of the beta-adrenergic signal transduction system were analyzed in kidney and liver membrane preparations from neonatal (2-3 days), mature (2 months), and old (2 years) rats. When comparing kidneys from adult to neonatal rats, we found a higher beta-receptor density and a higher percentage of beta(1)-receptor subtype, lower immunoreactive G(salpha)-protein, a lower ratio between the high and low molecular weight splice variant of G(salpha), lower immunoreactive G(ialpha)-protein, and lower basal adenylate cyclase activity. When comparing livers from adult to neonatal rats, we found lower beta-receptor density and basal adenylate cyclase activity. Very few differences could be detected when comparing mature to old kidneys or livers. Stimulated adenosine 3',5'-cyclic monophosphate (cAMP) synthesis was tissue- and age-dependent. In liver, G-protein- and beta-receptor-stimulated cAMP synthesis mirrored basal adenylate cyclase activity and was highest in liver from neonatal animals. In contrast, cAMP synthesis was significantly more stimulated in kidneys from mature animals than from neonatal and senescent rats. We conclude that: (i) the stoichiometry of the components within the beta-receptor/G-protein/adenylate cyclase complex is not fixed but is both tissue- and age-dependent; (ii) adenylate cyclase enzyme activity is possibly but not necessarily the rate-limiting step in the beta-receptor-mediated synthesis of cAMP; and (iii) there is in vivo evidence for a preferential co-expression of the large splice variant of the G(s)-protein and beta(2)-receptor subtype. It is speculated that this could have important physiological consequences for the development of the kidney.

Adenylyl Cyclases↗
PubMed2000

Properties of the ventricular adrenergic signal transduction system during ontogeny of spontaneous hypertension in rats.

The purpose of this study was to characterize adrenergic receptors and associated G proteins in ventricles of spontaneously hypertensive rats (SHRs) at different stages of development. The beta- and alpha1-adrenoceptor densities and subtype distribution, and beta-adrenoceptor-G protein coupling were studied by radioligand binding, and levels of G(Salpha), G(ialpha), and G(q/11alpha) protein species were determined by Western blotting in SHRs and Wistar-Kyoto (WKY) control rats aged 3.5 weeks, 3 months, and 8 months. In 3.5-week-old SHRs, both the beta-adrenoceptor density and the percentage of agonist high-affinity binding sites were higher than in age-matched WKY rats. The beta1/beta2-subtype distribution, the alpha1-adrenoceptor density, and the alpha1B/alpha1A-subtype distribution were similar in rats of both strains at all ages. Although essentially no differences in G(salpha) levels between SHRs and WKY rats were detected, higher G(ialpha) and lower Gq/1alpha concentrations were found in 3.5-week-old SHRs. In 3-month-old SHRs, increased levels of Gq/11alpha proteins were observed. In 8-month-old SHRs, none of the parameters was different from those of controls. We conclude that the differences in properties of the adrenergic signal transduction system between SHRs and WKY rats are exclusively observable before and at the onset of the overt hypertension. Moreover, the hypertensive genotype apparently affects G proteins more readily than adrenoceptors.

Animals↗
PubMed1996

Penetration of gentamicin and ofloxacin in human vitreous after systemic administration.

BACKGROUND: Data on the penetration of antibiotics into the aqueous humor in man and animals, as well as on the intravitreal penetration in animals, are numerous. Data on their intravitreal penetration in humans, however, are sparce. The intravitreal penetration of gentamicin was studied in different ocular pathologies to see whether these alter the vitreal pharmacodynamics. The intravitreal penetration of ofloxacin, a fluoroquinolone, was determined to see whether levels sufficient to treat infectious endophthalmitis could be reached. METHODS: The intravitreal penetration of gentamicin and ofloxacin was studied in patients undergoing pars plana vitrectomy for various ocular pathologies. Those with recent hemorrhages and those already receiving general antibiotic treatment were excluded. RESULTS: Gentamicin was found to penetrate the vitreous very poorly. No difference could be found between the various pathologies: trauma, diabetes, proliferative vitreoretinopathy, longstanding vitreous hemorrhage and macular pucker gave the same poor penetration. The ofloxacin levels were higher but did not reach the MIC90 levels of most organisms involved in bacterial endophthalmitis. CONCLUSION: The hemato-ocular barrier is more difficult to cross than originally thought. Different ocular pathologies do not alter the ocular barrier substantially. Ofloxacin alone does not seem to be sufficient for the treatment of established bacterial endophthalmitis.

Adolescent↗
PubMed1994

Effect of age on beta-receptors, Gs alpha- and Gi alpha- proteins in rat heart.

beta-adrenoceptors, Gs alpha- and Gi alpha-proteins were investigated in a crude plasma membrane preparation from ventricles of young (2-4 months) and senescent (22-24 months) Wistar rats. Receptor density, ligand affinity and beta 1/beta 2-receptor ratio were independent of the age of the rats. The percentage of beta-receptors coupled to G-proteins increased with age. An age-related increase in the level of Gs alpha (124%) was paralleled by an increase in the ratio between the high and low molecular weight form of Gs alpha. The level of Gi alpha-protein almost doubled (170%) upon aging. We conclude that the age-related differences are small at the level of the beta-adrenoceptor molecule, but that the increase in Gi alpha-proteins could be responsible for the age-related reduction in myocardial inotropic and chronotropic responses. Moreover, we suggest that the changes in degree of high affinity coupling between beta-receptor and Gs-protein are possibly linked to alterations in the ratio between the Gs-molecular weight subtypes.

Adenylyl Cyclases↗
PubMed1993

Hemodynamic and metabolic effects of flunarizine in experimental subarachnoid hemorrhage in dogs.

BACKGROUND AND PURPOSE: Cerebral blood flow and oxygen metabolism were measured and a cerebral angiography was performed in dogs with experimental subarachnoid hemorrhage to assess the relation between arterial narrowing (vasospasm) and the fall of blood flow. Cerebral blood volume and the cerebrovascular CO2 reactivity were also measured to estimate the cerebrovascular reserve. Several groups of dogs were treated with flunarizine in different regimens to assess its possible therapeutic effect. METHODS: The experiments were performed in the three-hemorrhage canine model for subarachnoid hemorrhage. Cerebral blood flow and cerebral oxygen metabolism were measured in anesthetized (nitrous oxide) dogs using positron emission tomography in combination with the 15O steady-state method. Basilar artery diameter was evaluated by digital subtraction angiography. RESULTS: In normal dogs, cerebral blood flow, oxygen consumption, and oxygen extraction ratio were 46.4 +/- 9.0 ml/100 ml per minute, 3.65 +/- 0.76 ml/100 ml per minute, and 39.9 +/- 3.4%, respectively; basilar artery diameter was 1.33 +/- 0.25 mm. Repeated subarachnoid blood injection (3 x 5 ml) reduced basilar artery diameter to < 20% of normal (p < 0.01). Cerebral blood flow was reduced by only 25% (p < 0.001); oxygen consumption was preserved at a low normal level by a 29% compensatory increase of the oxygen extraction (p < 0.001). Cerebral blood volume and cerebrovascular CO2 reactivity remained nearly normal. Early (after the first blood injection) peroral treatment with flunarizine (0.5 mg/kg daily) resulted in less severe basilar artery narrowing (56% of normal; p < 0.05 versus untreated). However, this treatment had no effect on cerebral blood flow, blood volume, oxygen consumption, and extraction. CONCLUSIONS: The observed fall of cerebral blood flow in experimental subarachnoid hemorrhage is not related to arterial narrowing but to an increased cerebrovascular resistance at the level of the small parenchymal vessels, and the latter, in contrast to arterial narrowing, is unaffected by flunarizine.

Animals↗
PubMed1993

Digital subtraction in multi-compartment arthrography of the wrist.

In a series of 23 patients with chronic and unexplained painful wrist, three-compartment arthrography was carried out using digital subtraction. Pathologic conditions were disclosed in 19 patients. Digital subtraction both allowed for a stronger diluting of the dye and for the demonstration of a larger amount of lesions of smaller size than conventional wrist-arthrography, as long as motion artefacts had been avoided. Obtaining successive views without having to wait for complete contrast resorption in the injected compartments represents a significant advantage. The importance of three-compartment injection is stressed and the best way to perform the technique is discussed. As it proved to be a fast and reliable examination procedure the authors advocate using digital subtraction arthrography of the wrist whenever the method is available. However, this relatively new technique does not rule out careful correlation between arthrographic findings and clinical complaints.

Adolescent↗
PubMed1992

Pharmacological characterization of a beta 3-receptor agonist (BRL 37,344) and a partial agonist (CGP 12,177A) in neonatal rat liver plasma membranes.

The pharmacological properties of BRL 37,344 (sodium-4-(2'-[2-hydroxy-2- (3-chloro-phenyl)ethylamino]-propyl)phenoxyacetatesesquihydrate), a beta 3-selective agonist, and CGP 12,177A) (-)-4-(3-t-butyl amino-2-hydroxypropoxy) benzimidazole-2-one], a non-selective beta-antagonist, recently characterized as a partial beta 3-agonist in rat adipose tissue, were studied in comparison with isoproterenol, a non-selective beta-agonist, in plasma membranes prepared from the livers of newborn rats. Competition binding curves obtained with [125I]iodocyanopindolol ([125I]CYP) as ligand and isoproterenol or BRL 37,344 as competitor were characterized by the presence of a high and a low affinity binding site; the high affinity binding site was no longer detectable when guanidylimidobisphosphate (GppNHp) was present in the incubation mixture. Competition curves with CGP 12,177A were monophasic and independent of GppNHp. In the presence of 10(-7) M of the beta 2-selective antagonist ICI 118,551 [erythro-(+/-)-1-(7-methylindan-4-yloxy)-3-isopropylamino butan-2-ol], a concentration which blocks most of the beta 2-receptors, ligand binding was reduced to 32% of its maximum. Under these conditions, isoproterenol further displaced the ligand, and competition curves still displayed the high and the low affinity binding sites; BRL 37,344, however, caused no further displacement of ligand, except at the highest concentrations. This suggests that BRL 37,344 occupies only the ICI 118,551-sensitive binding sites, i.e. beta 2-receptors. Isoproterenol and BRL 37,344 both stimulated adenylate cyclase (EC 4.6.1.1) activity concentration dependently, although the stimulating effect of BRL 37,344 was about half of what was found for isoproterenol. Furthermore, BRL 37,344 inhibited concentration dependently the isoproterenol-induced stimulation of adenylate cyclase, and the inhibition was dependent on the concentration of isoproterenol. The stimulating effect of isoproterenol and BRL 37,344 on adenylate cyclase was blocked by ICI 118,551, whereas the beta 1-selective antagonist CGP 20,712A ((+/-)-(2-(3-carbamoyl-4-hydroxyphenoxy)-ethylamino)-3-[4-(1-methy l-4- trifluoromethyl-2-imidazolyl)-phenoxy]-2-propanolmethane sulphonate) was ineffective. CGP 12,177A failed to stimulate adenylate cyclase activity. From these results we suggest that BRL 37,344 acts as a beta 2-partial agonist in rat liver. The results obtained with CGP 12,177A are typical for a non-selective beta-antagonist. We therefore conclude that there is no pharmacological evidence for the presence of beta 3-receptors in livers from newborn rats.

Adenylyl Cyclase Inhibitors↗
PubMed1992

Influence of age on the beta 1- and beta 2-adrenergic receptors in rat liver.

The influence of maturation and aging on beta receptors in rat liver was studied. Competition binding experiments with the nonselective beta-antagonist propranolol and the subtype selective antagonists ICI 118,551 (beta 2) ICI 89,406 (beta 1), and CGP 20,712A (beta 1) revealed the presence of a mixed beta 1 and beta 2 receptor population in crude plasma membrane preparations from livers of newborn, mature, and senescent rats. The percentage of beta 1 receptors was lowest in livers from newborn rats and was increased in livers from mature and senescent rats. This increase is caused by a decrease in beta 2 receptor density on maturation, although the beta 1 receptor density is nearly constant throughout the life span of the rat. Isoproterenol-stimulated adenylate cyclase activity was inhibited in livers from senescent rats by propranolol and ICI 118,551 and to a lesser extent by ICI 89,406 and CGP 20,712A. The isoproterenol-stimulated glucose output in hepatocytes from senescent rats was inhibited concentration dependently by propranolol, ICI 118,551, ICi 89,406, and CGP 20,712A. From these results we conclude that beta 1 and beta 2 receptors are present in livers from rats of the three age groups and that the beta 1 to beta 2 receptor ratio is increased in livers from mature and senescent rats compared with newborn rats. Both beta receptor subtypes are linked to the cAMP second messenger system in newborn and senescent rats; beta 1 and beta 2 receptors are equally involved in the regulation of glycogenolysis in hepatocytes from senescent rats.

Adenylyl Cyclases↗
PubMed1992

Elastofibroma dorsi: CT, MR and pathologic study in a new case.

As reported before elastofibroma dorsi is a rare benign tumor of elastic connective tissue with typical clinical and suggestive radiological features. We evaluated the CT and MR characteristics of this periscapular lesion in a new case, before and after contrast enhancement, and tried to determine in how far the nature and extent of the tumor can be predicted.

Back↗
PubMed1991

[Oroantral communication and its treatment].

The most frequent cause of an oroantral perforation is the extraction of an upper molar. In this article, this for a dental practitioner important entity is discussed in detail. After the etiopathology, clinical and roentgenological diagnosis is discussed. As 6.5% of perforations closes spontaneously, the question is raised wether all perforations should be surgically treated. Those different surgical techniques are then described and emphasis is thereby laid on the difference between a mere perforation and a fistula.

Humans↗
PubMed1991

[Subcutaneous emphysema of the oral floor during cleaning of a bridge fixed on an IMZ implant. Case report].

A case of subcutaneous emphysema following intraoral elimination of plaque and tooth shading, on a bridge fixed on implants, is presented. An instrument that produces a cleaning spray with a water-air-powder mixture was used. A few minutes after this cleaning procedure there was facial swelling. The patient experienced difficulties in breathing and in swallowing; symptoms of unilateral hearing loss were also noticed. The emphysema lasted for three days. Etiology, diagnosis, differential diagnosis, complications and management are discussed.

Dental Implantation, Endosseous↗
PubMed1990

Characterization of the beta-adrenergic transduction system in spleen mononuclear leukocyte membranes of young and senescent rats.

The effect of aging on some of the properties of the beta-adrenergic transduction system was determined in a membrane fraction of spleen mononuclear leukocytes from young (2-3 months) and old (24-25 months) rats. Receptor density was unchanged and the percentage of receptors in the high affinity configuration for isoproterenol was reduced with increasing age. Adenylate cyclase activity, either unstimulated or stimulated with forskolin, GTP or isoproterenol was not affected by aging. This suggests the presence of compensatory mechanisms in the beta-adrenergic signal transduction system of rat spleen mononuclear cells in order to ensure equal cAMP production for equal agonist stimulation.

Adenylyl Cyclases↗
PubMed1990

The beta-adrenergic transduction system in kidneys from young and senescent rats.

beta-Adrenoceptor density, ligand affinity, high-affinity agonist binding, basal adenylate cyclase activity and cAMP synthesis upon stimulation with either forskolin, F-, guanine nucleotides (GTP or GppNHp) or isoproterenol in the presence of the nucleotides were studied in membranes prepared from kidneys of young (2-3 month) and old (24-25 month) male Wistar rats. There is a significant (P less than 0.01) 62% increase in beta-receptor density, a significant (P less than 0.05) 115% decrease in ligand affinity, a significant (P less than 0.05) 33% decrease of high-affinity binding sites for (-)-isoproterenol and a significant (P less than 0.01) 151% decrease of the affinity of the high-affinity agonist binding site. Basal adenylate cyclase activity and the activity after stimulation with guanine nucleotides and forskolin were significantly higher in old animals as compared to young (P less than 0.01). Stimulation of the system with isoproterenol in the presence of GTP was more effective in old animals, although the P less than 0.05 level of significance was barely reached. It is suggested that age-dependent changes of the beta-adrenoceptors in rat kidney are similar to those described for lungs: changes at the different levels of the beta-adrenergic transduction chain associated with age are compensatory so as to ensure equal cAMP synthesis for a given agonist stimulation.

Adenylyl Cyclase Inhibitors↗
PubMed1990

Ossification of the cervical posterior longitudinal ligament with severe myelopathy and fatal outcome.

Ossification of the posterior longitudinal ligament is rare among Caucasians. We describe a new case with lethal outcome and we discuss the radiographic and pathologic findings. Posterior longitudinal ligament ossification is a benign disease in most cases, but it may cause severe myelopathy due to spinal stenosis. Diagnosis may be suspected or made on lateral views of the cervical spine and ascertained by CT.

Aged↗
PubMed1989

Effect of aging on properties and function of beta-adrenoceptors in rat lung.

beta-Adrenoceptor density and ligand affinity, basal adenylate cyclase activity and cAMP synthesis upon stimulation with forskolin, fluoride, guanine nucleotides (GTP or guanylyl imidodiphosphate (GppNHp) or isoproterenol in the presence of the nucleotides were studied in membranes prepared from lungs of young (aged 2-3 months) and of old (aged 24-25 months) male Wistar rats. There was a significant (P less than 0.05, 21%) increase in beta-receptor density and a significant (P less than 0.05, 38%) decrease in the percentage of high-affinity binding sites for isoproterenol. Both basal adenylate cyclase activity and that after stimulation with guanine nucleotides or isoproterenol in the presence of nucleotides were unaltered with age. Forskolin stimulation of cAMP synthesis was significantly reduced (by 24%, P less than 0.05) in tissues from older animals. It is suggested that the age-dependent changes in properties of beta-receptors in rat lungs are compensatory, in order to ensure equal cAMP production for equal agonist stimulation.

Adenylyl Cyclases↗
PubMed1989

Traumatic lumbosacral nerve root meningoceles. The value of myelography, CT and MRI in the assessment of nerve root continuity.

A case of traumatic lumbar meningoceles at four levels in combination with total and partial nerve root avulsion and with preservation of a nerve root is reported. Several diagnostic imaging techniques (myelography, CT, myelo-CT and MRI) are compared and their value in demonstrating the continuity of the nerve roots is discussed. MRI could assess the continuity of a nerve root in a traumatic meningocele, not demonstrable by myelography or myelo-CT. The combination of myelography, myelo-CT and MRI is likely to provide a complete diagnostic evaluation of nerve root lesions.

Adult↗