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A Raes

Publications and source records attributed to A Raes.

7 recordsLinked to original sources
PubMed1996

N-methyl-D-aspartate receptor activation by guanidinosuccinate but not by methylguanidine: behavioural and electrophysiological evidence.

Levels of methylguanidine (MG) and guanidinosuccinate (GSA) are known to be highly increased in uraemic patients. In the present work, the effects of these uraemic guanidino compounds on the excitatory amino acid system were investigated in vivo and in vitro. It was found that convulsions induced by intracerebroventricular GSA injection in mice were antagonized by N-methyl-D-aspartate (NMDA) receptor blockade, whereas those induced by MG were not significantly altered. Application of GSA (between 25 and 10,000 microM) to mouse spinal cord neurones in primary dissociated cell cultures, evoked depolarizing, inward whole-cell currents in a dose-dependent fashion and with reversal potential at 0 mV; MG did not produce such effects. GSA-induced whole-cell currents were caused by NMDA receptor activation since NMDA receptor antagonists (2-amino-5-phosphonovalerate, Mg2+ and ketamine) blocked GSA-evoked whole-cell currents completely and reversibly, whereas co-application of a non-NMDA receptor antagonist (6-cyano-7-nitroquinoxaline-2,3-dione) did not affect GSA-induced current. Evoked field potentials in CA1 region of rat hippocampal slices were completely abolished by GSA, and this effect was antagonized by NMDA receptor blockade. All data were consistent with selective agonist action of GSA upon the NMDA-type glutamate receptor. In view of the results presented here, it should be examined whether NMDA receptors contribute to the neurological complications of renal failure through GSA-induced inappropriate or excessive activation of NMDA receptors.

Animals↗
PubMed1996

Anticonvulsant activity of piperine on seizures induced by excitatory amino acid receptor agonists.

In traditional Chinese medicine, a mixture of radish and pepper is used to treat epilepsy. The presumptive effectiveness of this prescription might be due to the anticonvulsant actions of the principal component of pepper, the alkaloid piperine (CAS 94-62-2). The effects of piperine on convulsions induced in mice by agonists at different excitatory amino acid receptor subtypes were studied. Piperine was shown to significantly block convulsions induced by intracerebroventricular injection of threshold doses of kainate, but to have no or only slight effects on convulsions induced by L-glutamate, N-methyl-D-aspartate or guanidinosuccinate. Piperine suspensions, injected intraperitoneally, 1 h before injection of the threshold intracerebroventricular dose of kainate for the induction of clonic convulsions (1 nmol), blocked these convulsions with an ED50 (and 95% confidence interval) of 46 (25-86) mg/kg. Although piperine did block convulsions, induced by kainate, the compound does not appear to act as a kainate receptor antagonist. Whole-cell currents induced by the application of kainate to spinal cord cells in primary dissociated cultures were not affected by co-application of piperine.

Alkaloids↗
PubMed1995

Commercial television bladder dysfunction.

Bladderdysfunction seems to have an increasing frequency in infancy, and especially in children without obvious congenital organic or functional bladderdysfunction. The disorder seems is related with changes in our behaviour, that are stimulated by familial and social pseudo-reasons. Commercial interests and marketing play a major role. This leads to wrong dry-training, an exaggerated hygienic education, prudisheness, wrong toilet-posture, lack of time to void, post-poning, wrong drink- and void-pattern, wrong food-pattern and increasing constipation. Prevention is necessary by an adapted reeducation of parents ans society.

Adolescent↗
PubMed1995

Bladder function and non-neurogenic dysfunction in children: classification and terminology.

Urological function and dysfunction in children are different from function and dysfunction in adults. The dynamics of the urinary tract in children are more complex as development from simple reflex controlled infant bladder to mature bladder function takes place during the first five years of live. The most crucial event in this development is the maturation of the inhibition that takes place in the growing urinary tract. Apart from gaining neurological control over de lower urinary tract there is the physical growth of the bladder-sfincter unit. Otherwise in children there exist a large amount of structural organic congenital pathology of the lower urinary tract that can trouble the normal development. Finally there is the cognitive function that has no anatomical substrate in the lower urinary tract but which takes place in the central nervous system and which is influenced by training and which can play a major role in development of non structural functional dysfunction. In order to train a child adequately the anatomical structure needs to have undergone enough maturation. By training a child on a too early age one can help to develop non structural functional dysfunction. In a time where competition in dry-training is encouraged by commercial pressure and where parents have less time, so that they are urged to train their children dry, more and more non-structural functional dysfunction in children is seen. The most prominent symptom of maldevelopment of the urinary tract, be it structural or functional is urinary incontinence. It is the most common problem seen in the paediatric urology practice.(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗
PubMed1993

Use-dependent block of the pacemaker current I(f) in rabbit sinoatrial node cells by zatebradine (UL-FS 49). On the mode of action of sinus node inhibitors.

BACKGROUND: Zatebradine (UL-FS 49) is a drug with a specific bradycardiac electrophysiological profile. It reduces heart rate by lengthening the duration of diastolic depolarization in the sinoatrial (SA) node. The ionic basis of this action, however, is not clarified. METHODS AND RESULTS: We used the whole-cell patch-clamp technique to study the effects of zatebradine on ionic currents underlying diastolic depolarization of isolated rabbit SA node cells. Low concentrations of zatebradine simultaneously reduced diastolic depolarization rate and the pacemaker current I(f). The drug blocked the pacemaker current, I(f), in a use-dependent manner without causing a shift of its activation curve. At hyperpolarized potentials, unblock of I(f) occurred. Clinically relevant concentrations of the drug have little effect on the L-type calcium current or delayed rectifier potassium current. CONCLUSIONS: This use-dependent block of the If channel can account for most of the pharmacological characteristics of zatebradine and is probably the mechanism of heart rate reduction caused by this agent. Thus, the sinus node inhibitor zatebradine belongs to a new class of "I(f) blockers" with possible advantages over currently available drugs for the treatment of ischemic heart disease.

Animals↗
PubMed1977

The pattern of food and mortality in Belgium.

Belgians have been gradually shifting from a low ratio of polyunsaturated/saturated fat in their food to a higher one with lower total fat and cholesterol. This has occurred predominantly in the north, where the most obvious change is a decrease in butter consumption and an increase in margarine consumption. The northerners have a four to five times smaller intake of butter than the southerners and nearly double the intake of margarine. Evidence gathered over the past ten years reveals in the north a decreasing serum-cholesterol and in the south a significantly higher serum-cholesterol, associated with higher coronary morbidity and mortality. Life expectancy of males in the north is 2-4 years higher at birth and 2-2 years higher at the age of 30. It is concluded that the food habits of a population can be changed, with great benefit.

Adult↗