BackgroundAnimal studies have revealed seasonal patterns in cerebrospinal fluid (CSF) monoamine (MA) turnover. In humans, no study had systematically assessed seasonal patterns in CSF MA turnover in a large set of healthy adults.Methodology/Principal FindingsStandardized amounts of CSF were prospectively collected from 223 healthy individuals undergoing spinal anesthesia for minor surgical procedures. The metabolites of serotonin (5-hydroxyindoleacetic acid, 5-HIAA), dopamine (homovanillic acid, HVA) and norepinephrine (3-methoxy-4-hydroxyphenylglycol, MPHG) were measured using high performance liquid chromatography (HPLC). Concentration measurements by sampling and birth dates were modeled using a non-linear quantile cosine function and locally weighted scatterplot smoothing (LOESS, span = 0.75). The cosine model showed a unimodal season of sampling 5-HIAA zenith in April and a nadir in October (p-value of the amplitude of the cosine = 0.00050), with predicted maximum (PCmax) and minimum (PCmin) concentrations of 173 and 108 nmol/L, respectively, implying a 60% increase from trough to peak. Season of birth showed a unimodal 5-HIAA zenith in May and a nadir in November (p = 0.00339; PCmax = 172 and PCmin = 126). The non-parametric LOESS showed a similar pattern to the cosine in both season of sampling and season of birth models, validating the cosine model. A final model including both sampling and birth months demonstrated that both sampling and birth seasons were independent predictors of 5-HIAA concentrations.ConclusionIn subjects without mental illness, 5-HT turnover shows circannual variation by season of sampling as well as season of birth, with peaks in spring and troughs in fall.

Our data suggest that cluster headache is associated with an impaired dopaminergic stimulation. This finding supports the body of evidence that cluster headache is associated with a functional abnormality of the hypothalamus and that this association is a primary (i.e. idiopathic) and not a secondary phenomenon during the bout.

Abstractobjective The use of mobile phones can improve and strengthen (preventive) health care in lowand middle-income countries. We aimed to retrospectively assess the response patterns of participants in free SMS health education quizzes in Uganda.methods Study participants were employees of two companies and their community networks. We investigated how quickly individuals responded to quiz question(s) and assessed possible influencing factors. Cox regression and ANOVA analyses were used.results Fifty percentage of responders answered within 50 min. The response chance declined with every additional day after sending an incentive via SMS (Hazard Ratio 0.993, CI 95% 0.981-0.984). Quiz topics influenced both participation rates and response time. Response time was shortest for questions on HIV and sexual behaviour. Response rates were high for HIV (79%) and malaria (78.4%), but only 37.4% for demographic topics. Network providers had a substantial effect on response behaviour.conclusion Interactive SMS programs are a fast method to reach the target population and incentives increase response rates. The most important factor influencing response time and participation rate is the network provider. Future research should focus on developing evidence-based guidelines for the design, implementation and evaluation of SMS-based interventions.

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