PTGS1 and Stroke: The noun phrases usually constitute the cluster labels and are extracted from the titles of the cited articles using the log-likelihood ratio (LLR) algorithm, such as #0 cytokines, #1 reactive astrocytes, #2 NADPH oxidase, #3 tpa, #4 bone marrow chimeras, #5 hypoxia, #6 neurogenesis, #7 central nervous system, #8 stroke recovery, #9 tnf, #10 intracerebral hemorrhage, #11 tight junctions, #12 inflammatory cytokines, #13 reactive blue 2, #14 bradykinin, #15 microRNA, #16 neuropathology, #17 cyclooxygenase-1, #18 memory (Figure 6B).