Background and Purpose-Epidemiological studies have described an association between low vitamin B6 (measured as pyridoxal 5Ј-phosphate [PLP]) and ischemic stroke, independent of homocysteine (tHcy). We investigated B6 status, tHcy, and inflammation (measured by C-reactive protein [CRP]) in patients with stroke and controls. Methods-Consecutive cases with new ischemic stroke were compared with matched controls. Fasting tHcy, PLP, and CRP were measured. Results-The adjusted odds ratio of low PLP in the highest compared with the lowest CRP quartile was 16.6 (2, 139.9, Pϭ0.01

Stem cells in the shoot apical meristem (SAM) of plants are the self-renewable reservoir for leaf, stem, and flower organogenesis. Stem-cell fate and population size are subject to regulation by complex intrinsic signals and environmental cues to ensure balanced plant development, survival, and longevity. Peptides secreted from the shoot stem cells have pivotal roles in controlling cell identity, proliferation, and differentiation through multiple receptor kinase complexes. The best-characterized in vivo and in vitro peptide ligands are the 12-amino acid (aa) and the arabinosylated 13-aa CLAVATA3 peptides (CLV3p) that are perceived by multiple receptors with partially overlapping and distinct expression patterns and functions in the SAM. The primary molecular and cellular signaling mechanisms after the occurrence of ligand-receptor interaction remain elusive. Integrated analyses provide novel evidence for differential peptide-receptor signaling in the dynamic regulation of stem-cell homeostasis and fitness. Surprisingly, the 12-aa CLV3p can trigger immune signaling and limit pathogen invasion via the flagellin receptor kinase FLS2, suggesting a previously unrecognized molecular mechanism underlying enhanced immunity in the SAM area. Because pattern recognition receptor signaling in immune responses also profoundly intercepts plant development, peptide-receptor kinase signaling in immunity and development may share a common evolutionary origin.

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