The uptake and elimination of 20 structurally diverse tetra- to heptachlorinated biphenyls were studied in zebrafish (Danio rerio), three-spined stickleback (Gasterosteus aculeatus), and Arctic char (Salvelinus alpinus). The polychlorinated biphenyls (PCBs) were administered to the fish through food, intraperitoneal injection of peanut oil, or intraperitoneal implantation of silicone capsules. The retention of the PCBs in fish exposed through their diet was related with the substitution patterns of the compounds. Ortho-substituted congeners with no unsubstituted meta-para positions had high biomagnification potential. PCBs with low biomagnification all had adjacent vicinal hydrogens, indicating that congeners with this feature may have been metabolically eliminated. The retention characteristics of the PCBs in the diet-exposed and the injected zebrafish were similar. The pattern of congeners in Arctic char indicates that they have a lower capacity to metabolize PCBs compared to three-spined sticklebacks and zebrafish. The levels in the fish exposed to the PCBs through a silastic implant were negatively correlated with the hydrophobicity of the congeners. Most probably congener-specific release rates of the PCBs from the implants mask their retention characteristics. It is suggested that food, mimicking the natural intake route, should be used in PCB exposure studies to validate extrapolations to natural situations.
To assess the prevalence of chronic insomnia and the periodicity of headache attacks in an Arctic cluster headache population.
Cluster headache is a sleep-related disorder, and attacks have both circadian and circannual rhythmicity.
Through a retrospective hospital chart review, we identified all subjects diagnosed with episodic cluster headache (ICD-10 G 44.0) at the Neurological Departments in Northern Norway (located north of 66°33'N) between January 1, 2000 and December 31, 2010. Patients with a confirmed diagnosis (ICHD-2) received a comprehensive questionnaire covering demographic data, clinical characteristics, sleep, and periodicity of attacks.
A total of 196 subjects were registered, and 178 received the questionnaire. The response rate was 88/178 (49%). Fifty-eight men (aged 49.2?±?13.6) and 12 women (aged 49.7?±?15.5) were included. Forty percent of the responders suffered from chronic insomnia (Diagnostic and Statistical Manual of Mental Disorders 4th edition). Forty-nine percent of the responders and 42% of the non-responders were shift workers, which is much higher than compared with the general population (24%). Insomnia was significantly associated with shift work and experiencing longer-lasting cluster bouts. One third attributed their insomnia to the cluster headache. Thirty-seven percent reported a seasonal predilection of the cluster periods, and 58% a diurnal periodicity of attacks. Eighty percent often or always had headache attacks during sleep, the most frequent time interval being at 12:00-4:00?am. Shift workers were significantly more likely to see lack of sleep as a cluster attack trigger than daytime workers.
Chronic insomnia and shift work seem to be common among Arctic cluster headache patients. The small number of subjects included in this study implies that conclusions should be drawn with caution, but the findings support the idea of cluster headache as a circadian rhythm disorder.
Syringomyelia (SM) is common in the Cavalier King Charles Spaniel (CKCS). Dogs with syringes express clinical signs or might be clinically silent.
To investigate the prevalence and heritability of symptomatic SM, the association between clinical signs and magnetic resonance imaging (MRI) findings, and long-term outcome.
All CKCS registered in the Danish Kennel Club in 2001 (n = 240).
A cross-sectional questionnaire-based prevalence study validated by telephone interviews and clinically investigated clinical signs of SM. Dogs were 6 years at the time of investigation. A prospective observational litter study including clinical investigations, MRI and 5-year follow-up of symptomatic and asymptomatic siblings. Heritability was estimated based on the scale of liability in the study population and litter cohort.
The cross-sectional study estimated a prevalence of symptomatic SM at 15.4% in the population. Thirteen symptomatic and 9 asymptomatic siblings participated in the litter study. Spinal cord syringes were confirmed in 21 of 22 littermates (95%). Syrinx diameter and mean syrinx : spinal cord ratio were significantly correlated with clinical signs (P
Age-dependent changes in insulin action and body fat distribution are risk factors for the development of type 2 diabetes. To examine whether the accumulation of visceral fat (VF) could play a direct role in the pathophysiology of insulin resistance and type 2 diabetes, we monitored insulin action, glucose tolerance, and the expression of adipo-derived peptides after surgical removal of VF in aging (20-month-old) F344/Brown Norway (FBN) and in Zucker Diabetic Fatty (ZDF) rats. As expected, peripheral and hepatic insulin action were markedly impaired in aging FBN rats, and extraction of VF (accounting for approximately 18% of their total body fat) was sufficient to restore peripheral and hepatic insulin action to the levels of young rats. When examined at the mechanistic level, removal of VF in ZDF rats prevented the progressive decrease in insulin action and delayed the onset of diabetes, but VF extraction did not alter plasma free fatty acid levels. However, the expression of tumor necrosis factor-alpha and leptin in subcutaneous (SC) adipose tissue were markedly decreased after VF removal (by approximately three- and twofold, respectively). Finally, extracted VF retained approximately 15-fold higher resistin mRNA compared with SC fat. Our data suggest that insulin resistance and the development of diabetes can be significantly reduced in aging rats by preventing the age-dependent accumulation of VF. This study documents a cause-and-effect relationship between VF and major components of the metabolic syndrome.