Life in a dark biosphere: a review of circadian physiology in "arrhythmic" environments.

Most of the life with which humans interact is exposed to highly rhythmic and extremely predictable changes in illumination that occur with the daily events of sunrise and sunset. However, while the influence of the sun feels omnipotent to surface dwellers such as ourselves, life on earth is dominated, in terms of biomass, by organisms isolated from the direct effects of the sun. A limited understanding of what life is like away from the sun can be inferred from our knowledge of physiology and ecology in the light biosphere, but a full understanding can only be gained by studying animals from the dark biosphere, both in the laboratory and in their natural habitats. One of the least understood aspects of life in the dark biosphere is the rhythmicity of physiology and what it means to live in an environment of low or no rhythmicity. Here we describe methods that may be used to understand rhythmic physiology in the dark and summarise some of the studies of rhythmic physiology in "arrhythmic" environments, such as the poles, deep sea and caves. We review what can be understood about the adaptive value of rhythmic physiology on the Earth's surface from studies of animals from arrhythmic environments and what role a circadian clock may play in the dark.

Comparing Zonisamide With Sodium Valproate in the Management of Migraine Headaches: Double-Blind Randomized Clinical Trial of Efficacy and Safety.

BACKGROUND: Migraine is one of the most debilitating medical conditions and has a high socioeconomic burden. As conventional therapeutic methods do not entirely alleviate the symptoms, new alternatives are being considered. OBJECTIVES: This study evaluates the efficacy and safety of zonisamide compared with sodium valproate in the management of migraine headaches. PATIENTS AND METHODS: In the current double-blind, parallel, randomized, controlled trial, 96 patients with a migraine diagnosis based on the international headache society (HIS) criteria were selected. They were divided randomly into two groups; the case group was given zonisamide, and sodium valproate was given to a control group. In addition to the side effects of the drugs, the severity, duration, and frequency of migraine attacks were evaluated at baseline and at three months. RESULTS: The 96 selected patients were divided randomly into two treatment groups (zonisamide n = 48, sodium valproate n = 48). Seven patients were excluded from analysis because of early dropout, leaving 89 (n = 45; n = 44) patients for analysis. While using zonisamide, six (13%) patients complained of fatigue, and two (4%) patients encountered noticeable appetite and weight loss. In the control group, five (11%) patients reported dizziness, and four (9%) patients faced obvious appetite and weight gain. Both drugs were considerably efficient in reducing further attacks. There was no statistically significant correlation between frequency or severity of migraine attacks and the drug used for treatment in three months of follow-up. CONCLUSIONS: Both medications are effective in reducing migraine attacks. It will be important to consider the drugs' adverse effects and availability and patients' medical and socioeconomic condition to select the appropriate treatment.

The Role of Antiepileptic Treatment in the Recurrence Rate of Seizures After First Attack: A Randomized Clinical Trial.

OBJECTIVE: Epilepsy is a serious, potentially life-shortening brain disorder that occurs in patients of all ages and races. A total of 2-4% of people have experienced seizures at least once in their lifetime. Although treatment usually begins after a seizure, it is an important question whether the first cases of seizure do need to be treated by antiepileptic drugs. In this manner, we compare the recurrence rates of epilepsy in first seizure patients treated with sodium valproic acid as an antiepileptic drug versus a placebo. MATERIAL & METHODS: In a randomized clinical trial study, 101 first seizure patients were randomly divided into two groups: one group was treated with antiepileptic drugs (sodium valproate 200mg, three times a day) and the other group was given a placebo. The recurrence rate of seizures was evaluated and compared between the groups after 6 months of follow up. RESULTS: Eight recurrence cases were detected. All recurrence cases came from the placebo group, with four patients suffering an additional seizure after four months and between 4-6 month follow up. A comparison of recurrence rate detected a statistically significant difference between the drug group and placebo group. CONCLUSION: Our data shows that the recurrences occurred only in the placebo group with the difference between the recurrence rates in the placebo versus drug-treated was significant. Our results suggest that drug therapy for people after their first seizure attack might reduce the probability of seizure recurrence.