In several pedigrees of early onset familial Alzheimer's disease (FAD), point mutations in the beta-amyloid precursor protein (APP) gene are genetically linked to the disease. This finding implicates APP in the pathogenesis of Alzheimer's disease in these individuals. To understand the in vivo function of APP and its processing, we have generated an APP-null mutation in mice. Homozygous APP-deficient mice were viable and fertile. However, the mutant animals weighed 15%-20% less than age-matched wild-type controls. Neurological evaluation showed that the APP-deficient mice exhibited a decreased locomotor activity and forelimb grip strength, indicating a compromised neuronal or muscular function. In addition, four out of six homozygous mice showed reactive gliosis at 14 weeks of age, suggesting an impaired neuronal function as a result of the APP-null mutation.

Sumatriptan, a 5HT1B/1D-receptor agonist, is clinically effective as an antimigraine agent. Its therapeutic action may result partly from vasoconstriction of excessively dilated cranial blood vessels (a 5HT1B-receptor mediated response). The antimigraine activity of sumatriptan may also result from inhibition of the release of vasoactive neuropeptides from trigeminal sensory fibres within the meninges. The identity of the 5HT1B/1D-receptor subtype mediating this effect is unknown. Using 5HT1D- and 5HT1B-receptor-specific antibodies we have demonstrated a differential distribution of these receptor subtypes within the human trigemino-cerebrovascular system. Only 5HT1B-receptor protein was detected on dural arteries. In contrast, only 5HT1D-receptor protein was detected on trigeminal sensory neurones including peripheral and central projections to dural blood vessels and to the medulla. Within the medulla 5HT1D-receptor protein was confined to discrete areas associated with the trigeminal sensory system. These findings have important implications for the design of new antimigraine drugs.

Vitamin D deficiency is implicated in multiple disease conditions and accumulating evidence supports that the variation in serum vitamin D (25(OH)D) levels, including deficiency, is under strong genetic control. However, the underlying genetic mechanism associated with vitamin 25(OH)D concentrations is poorly understood. We earlier reported a very high prevalence of vitamin D deficiency associated with an increased risk for type 2 diabetes and obesity in a Punjabi Sikh diabetic cohort as part of the Asian Indian diabetic heart study (AIDHS). Here we have performed the first genome-wide association study (GWAS) of serum 25(OH)D on 3538 individuals from this Punjabi Sikh population. Our discovery GWAS comprised of 1387 subjects followed by validation of 24 putative SNPs (P <10−4) using an independent replication sample (n = 2151) from the same population by direct genotyping. A novel locus at chromosome 20p11.21 represented by rs2207173 with minor allele frequency (MAF) 0.29, [β = −0.13, p = 4.47 × 10−9] between FOXA2 and SSTR4 was identified to be associated with 25(OH)D levels. Another suggestive association signal at rs11586313 (MAF 0.54) [β = 0.90; p = 1.36 × 10−6] was found within the regulatory region of the IVL gene on chromosome 1q21.3. Additionally, our study replicated 3 of 5 known GWAS genes associated with 25(OH)D concentrations including GC (p = 0.007) and CYP2R1 (p = 0.019) reported in Europeans and the DAB1 (p = 0.003), reported in Hispanics. Identification of novel association signals in biologically plausible regions with 25(OH)D metabolism will provide new molecular insights on genetic drivers of vitamin D status and its implications in health disparities.

We reviewed our experience with 54 cluster headache patients (23 episodic, 31 chronic) admitted to our headache center 64 tines over the past five years and treated with repetitive intravenous dihydroergotamine (IV DHE). DHE therapy was initiated on admission and prophylactic medication regimens were started or adjusted. All 54 patients had complete relief of their cluster headache, usually within two days. Most (82.8%) had no side effects. The average length of hospitalization was 6.7 days. At the three month followup, 92.9% of the episodic cluster patients were headache-free and 7.1% had a 50-74% improvement; at six months, all were headache-free. Of the chronic cluster patients, 44.4% were headache-free at three months and 52.8% had at least 50% improvement. At six months, 75% were headache-free and 22.2% were at least 75% improved, probably as a result of continued prophylactic medication. Repetitive IV DHE safely, rapidly, and effectively controls cluster headache.