[Cognitive impairment due to intensive use and overdoses of gammahydroxybutyric acid (GHB)]. / Cognitieve schade door intensief gebruik en overdoses van GHB.

BACKGROUND: In several countries, including the Netherlands, the use of GHB seems to be increasing. Many recreational users of GHB consider the drug to be harmless and to have no serious side effects. In recent years the number of patients with GHB addition has been increasing steadily. AIM: To draw attention to the possible development of neurotoxicity due to chronic and intensive use of GBH. METHOD: We reviewed the literature using PubMed. RESULTS: Several studies point to an increase in the number of incidents arising from the risky use of GHB or from a GHB overdose. Other drugs, such as ketamine and alcohol, are known to cause neurotoxicity, leading to cognitive impairment. As outlined in this review article, GHB , alcohol and ketamine show clear similarities in their mechanism of action. This suggests that GHB might have almost the same neurotoxic effects as ketamine and alcohol. An overdose of GHB, just like binge-drinking and a high dose of ketamine, may lead to a coma that probably harms the brain, particularly if comas occur repeatedly. CONCLUSION: The risk of neurotoxicity is likely to increase with chronic, intensive use of GHB, which is a feature of GHB-addition. We therefore advocate research into the possible toxic effects of GHB in the long term, involving, for instance, the study of lasting effects on the cognitive functions of GHB users and former users.

mCPP: an undesired addition to the ecstasy market.

A new ecstasy-like substance, meta-chlorophenylpiperazine (mCPP), has been detected in street drugs in the Netherlands. Theoretically, mCPP possesses the potential to become a non-neurotoxic alternative for methylenedioxymethamphetamine (MDMA), the regular psychoactive substance of ecstasy. Since its introduction on the Dutch market of synthetic drugs, the percentage of mCPP-containing tablets has increased, including both tablets that contain only mCPP and tablets containing a combination of mCPP and MDMA. These tablets occur in many different colours, shapes and sizes and with various logos, making it impossible to distinguish mCPP-containing tablets from regular MDMA tablets. In addition, the reports of users concerning the effects of mCPP are predominantly negative. All these aspects together lead to the conclusion that mCPP is an undesired addition to the ecstasy market from the user's perspective.

Transitive predatory relationships of spider species (Arachnida, Araneae) in laboratory tests.

Interspecific predation of spiders was studied in the laboratory in view of possible competition in the wild. Certain species killed other species even if handicapped by smaller size. Thirty eight spider species were involved in such a relationship and their predatory relationships were significantly reliable and transitive ('linear' or 'non-triangular'). A theridiid species (Theridion tinctum) showed the highest rank in terms of killing seven 'beta species', i.e. species capable of killing at least one alien species of larger size than themselves. Another theridiid (Steatoda grossa) obtained the second rank by killing five beta species. Experiments in both the wild and laboratory may, further, investigate other factors than body size that may be relevant to competition, such as behaviour-related characteristics (e.g. web structure and biting speed) and ecological factors (e.g. different susceptibilities of the species to parasite or predator attack).

A Pro51Ser mutation in the COCH gene is associated with late onset autosomal dominant progressive sensorineural hearing loss with vestibular defects.

We analysed a Dutch family with autosomal dominant non-syndromic progressive sensorineural hearing loss and mapped the underlying gene defect by genetic linkage analysis to a 11.0 cM region overlapping the DFNA9 interval on chromosome 14q12-q13. Clinically, the Dutch family differs from the original DFNA9 family by a later age at onset and a more clearly established vestibular impairment. A gene that is highly and specifically expressed in the human fetal cochlea and vestibule, COCH (previously described as Coch5B2 ), was mapped to the DFNA9 critical region. Sequence analysis revealed a 208C-->T mutation in the COCH gene, resulting in a Pro51Ser substitution in the predicted protein in all affected individuals of the family but not in unaffected family members and 200 control individuals. The same mutation was also identified in three apparently unrelated families with a similar phenotype, suggesting the presence of a Dutch founder mutation. The function of COCH is unknown but several characteristics of the protein point to a structural role in the extracellular matrix. The mutant serine at position 51 is situated between cysteines and possibly interferes with proper COCH protein folding or its interaction with extracellular matrix proteins.