Biomedical subjects
B Arends
Publications and source records attributed to B Arends.
Individual differences in the effects of serotonergic anxiolytic drugs on the motivation to self-administer cocaine.
Numerous clinical studies have indicated that lifetime anxiety is highly prevalent in drug addicts. In the treatment of drug abuse, dually diagnosed drug addicts may benefit from pharmacological intervention strategies that alleviate the psychiatric symptomatology. We have previously shown that rats with different coping strategies in a stressful environment show strong differences in the motivation to self-administer cocaine. That is, cocaine self-administration under a progressive ratio (PR) schedule of reinforcement was enhanced in high grooming (HG) rats as compared with low grooming (LG) rats. To identify the pharmacological basis of these differences, we tested the acute effects of several anxiolytic drugs on cocaine self-administration in HG and LG rats under a PR schedule of reinforcement. Chlordiazepoxide increased PR responding in both the HG and LG rats, while the selective corticotrophin releasing hormone 1 receptor antagonist R121919 had no effect on cocaine self-administration under the PR schedule. Interestingly, buspirone and fluoxetine decreased PR responding in HG rats only and thereby abolished the individual differences in PR responding between HG and LG rats. In support of the differential effects of the serotonergic drugs on PR responding in HG and LG rats, we found that the in vitro electrically evoked release of [3H]serotonin from mesocorticolimbic brain slices was reduced in the medial prefrontal cortex, substantia nigra and nucleus accumbens core, and increased in the nucleus accumbens shell of HG rats relative to LG rats. These findings show that serotonergic anxiolytics abolish the pre-existing individual differences in cocaine self-administration between HG and LG rats, which show differences in the reactivity of serotonergic neurons. This suggests that the effectiveness of pharmacological interference may depend on the neurochemical and motivational state of the individual.
Toothache from composite filling.
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Evaluation of surgical gamma probes for radioguided sentinel node localisation.
By using a surgical gamma probe after peritumoral injection of a radioactive tracer, the surgeon can identify the sentinel, or first, nodal site of regional metastasis in clinically node-negative patients. In the near future, the pathological status of this node will have an important impact on the treatment strategy in breast cancer and melanoma patients. This article reviews the necessary requirements for the instrument, such as: absolute sensitivity, spectral resolution, angular sensitivity and response ratio to the radioactive source at depth. In addition, ergonomic characteristics are important. The surgeon must consider the above characteristics, as they influence operational handling. Four commercially available surgical gamma probes were subjected to laboratory tests to appraise the extent to which they fulfilled these criteria. The results for each gamma probe are summarised and discussed.<
Differences between anti-myeloperoxidase- and anti-proteinase 3-associated renal disease.
We performed a retrospective study of the clinical features, the pattern of the pre-treatment renal function loss, the renal morphology and the outcome in 92 patients with anti-neutrophil cytoplasmic autoantibodies directed against proteinase 3 (aPR3; N = 46) or myeloperoxidase (aMPO; N = 46). Patients with aMPO had a higher median age than patients with a PR3 (63 and 56 years; P < 0.05). The mean (+/- SD) number of affected organs in the aPR3 group exceeded that of the aMPO group (3.9 +/- 1.4 and 2.2 +/- 1.1; P < 0.01). The prevalence of renal involvement did not differ between patients with aPR3 and aMPO (83% and 67%, respectively; NS). Pre-treatment renal function deteriorated significantly faster in aPR3- than in aMPO-associated renal disease. The kidney biopsies from patients with aPR3 showed a higher activity index (10.2 +/- 3.8 and 7.3 +/- 3.2; P < 0.03) and a lower chronicity index (4.5 +/- 2.6 and 7.0 +/- 3.1; P < 0.02) than biopsies from patients with aMPO. The kidney survival at two years was 73% in patients with aPR3- and 61% in patients with aMPO-associated renal disease (NS). We conclude that renal function generally deteriorates faster in aPR3- than in aMPO-associated renal disease. This goes together with more active renal lesions in patients with aPR3 and more chronic renal lesions in patients with aMPO. Despite these differences, there is no difference in outcomes between both antibody groups.
Influence of prolonged submaximal exercise on the pharmacokinetics of verapamil in humans.
The influence of prolonged submaximal exercise on the pharmacokinetics of verapamil was studied in normal volunteers both after i.v. injections of 0.13 mg/kg body weight as well as after one oral dose of 80 mg of the calcium entry blocker. Each dose was given on a rest day and on an exercise day. On the rest day, the terminal phase half-life (t1/2) of verapamil averaged 161 +/- 23 min after i.v. injection of the drug. The total clearance was 772 +/- 125 ml/min, and the area volume of distribution was 198 +/- 53 L. These parameters were not altered on the exercise day. Neither did exercise have any influence on the pharmacokinetic parameters determined after oral application of verapamil. This study shows that prolonged submaximal exercise has no influence on the pharmacokinetics of verapamil.