Cannabinoid agonists in the treatment of blepharospasm--a case report study.

The benign essential blepharospasm is a subliminal form of primary torsion dystonia with still uncertain aetiology. It is characterized by involuntary convulsive muscle contractions of the M. orbicularis occuli, accompanied by unbearable pain of the cornea, eye bulb and the muscle itself. It has been suggested that blepharospasm is neurobiologically based on a dysfunction of the basal ganglia and an impairment of the dopamine neurotransmitter system. Therefore, therapy of blepharospasm contains administration of anticholinergic- and tranquillizing drugs as well as botulinum toxin as neuromuscular blocking agent. However serious side effects can be observed as well as failure of therapy. In the brain a dense co-localisation of cannabinoid (CB1) and dopamine (D2)-receptor was identified which had been associated with the influence of cannabinoids on the dopaminergic reward system. Additionally, it has been demonstrated that cannabinoids may have an impact on the central GABAergic and glutaminergic transmitter system and thus might be involved in the influence of movement control. In the present case we administered the cannabinoid receptor agonist Dronabinol (Delta-9-Tetrahydrocannabinol) to a woman suffering from severe blepharospasm. Multiple treatments with botulinum toxin did not reveal a long-lasting beneficial effect. By contrast, treatment with 25 mg Dronabinol for several weeks improved the patients' social life and attenuated pain perception remarkably. This case study demonstrates that the therapy with a cannabinoid agonist may provide a novel tool in the treatment of blepharospasm and maybe of other multifactorial related movement disorders.

Rejoining of radiation-induced DNA double-strand breaks: pulsed-field electrophoresis analysis of fragment size distributions after incubation for repair.

The repair of radiation-induced DNA double-strand breaks (DSBs) is frequently investigated by measuring the time-dependent decrease in the fraction of fragmented DNA that is able to enter electrophoresis gels. When transformed into equivalent doses without repair, such measurements are thought to reflect the removal of DSBs, and they typically exhibit a fast initial component and a decreasing rate at longer repair intervals. This formalism, however, assumes that the spatial distribution of unrejoined breakage resembles the pattern of induction of DSBs. While the size distributions for initial fragmentation, such as that resolved by conventional pulsed-field gel electrophoresis (PFGE) (between about 10(5) and 10(7) bp), are well known to agree with the prediction of random breakage, no data are available from studies explicitly testing this relationship for residual breakage. Therefore, Chinese hamster V79 cells and MeWo (human melanoma) cells were irradiated with different doses (10-100 Gy) or were incubated for repair for up to 4 h after a single dose of 100 Gy (V79) or 90 Gy (MeWo) before being subjected to PFGE. Fragment size distributions were calculated by convolution of the PFGE profiles with an appropriately generated size calibration function. The results clearly demonstrate an over-representation of smaller fragments (below about 2-3 Mbp) compared to the prediction of randomness for residual breakage. In consequence, the time-dependent decrease of dose-equivalent values calculated from data on the fraction released may not directly reflect DSB rejoining rates. The present findings are compatible with an earlier suggestion of slow rejoining of breaks which have been induced as multiple breaks (two or more) in large chromosomal loops, thus also predicting an increase of the slowly rejoining DSB fraction with increasing dose.