Functional MRI of sentence comprehension in children with dyslexia: beyond word recognition.

Sentence comprehension (SC) studies in typical and impaired readers suggest that reading for meaning involves more extensive brain activation than reading isolated words. Thus far, no reading disability/dyslexia (RD) studies have directly controlled for the word recognition (WR) components of SC tasks, which is central for understanding comprehension processes beyond WR. This experiment compared SC to WR in 29, 9-14 year olds (15 typical and 14 impaired readers). The SC-WR contrast for each group showed activation in left inferior frontal and extrastriate regions, but the RD group showed significantly more activation than Controls in areas associated with linguistic processing (left middle/superior temporal gyri), and attention and response selection (bilateral insula, right cingulate gyrus, right superior frontal gyrus, and right parietal lobe). Further analyses revealed this overactivation was driven by the RD group's response to incongruous sentences. Correlations with out-of-scanner measures showed that better word- and text-level reading fluency was associated with greater left occipitotemporal activation, whereas worse performance on WR, fluency, and comprehension (reading and oral) were associated with greater right hemisphere activation in a variety of areas, including supramarginal and superior temporal gyri. Results provide initial foundations for understanding the neurobiological correlates of higher-level processes associated with reading comprehension.

Increased response to antigen and histamine release in smaller sensitized canine bronchi.

We studied the Schultz-Dale response in vitro in large and small size branches from 3rd to 6th generation bronchi from ragweed-sensitized dogs. The response to electric field stimulation (EFS) increased after antigen from 65.56 +/- 8.11 to 78.6 +/- 9.0 mN/mm2 of smooth muscle (P < 0.01), but no topographical difference was observed. The response to ragweed (% of the response to EFS) was 158.3 +/- 12 and 67.1 +/- 11.7 in strips from small and large branches respectively (P < 0.01), while no difference was observed between generations; when clustering bronchi according to dimension, it was 129.9 +/- 13.4 in small and 71.9 +/- 19.8 in large bronchi (P < 0.01). Histamine released from small and large branches was 2.90 +/- 1.01 and 0.76 +/- 0.20 (ng/mg of tissue) respectively (P < 0.05); no difference was found between generations. In conclusion, in sensitized dogs a greater response to antigen, which involves a higher histamine release, occurs in small compared to large bronchi. We suggest that control of distribution of ventilation occurs mainly at small bronchi level, which becomes the elective tissue to study the Schultz-Dale response. Finally, the classification of bronchi into generations is inadequate to study allergic bronchospasm.

Time course of production of cytokines and prostaglandin E2 by macrophages isolated after thermal injury and bacterial translocation.

The relationship of translocation of bacteria from the gut of burned guinea pigs and the in vitro production of tumor necrosis factor (TNF), interleukin (IL)-1 and IL-6, and prostaglandin E2 (PGE2) by lipopolysaccharide (LPS)-stimulated mesenteric lymph node and splenic macrophages was investigated at two early times after thermal injury. Two hr postburn, there was a large number of translocated bacteria in the mesenteric lymph nodes and a large proportion was killed; at 24 hr postburn, there were fewer translocated bacteria, but a large proportion was viable. In some cases, there were very large differences compared to controls in the amounts of TNF, IL-6, and PGE2, but not of IL-1, produced by the macrophages at different times postburn and at different in vitro incubation times. The results suggest that the macrophages were primed by the burn or the translocated bacteria to produce in vitro different and sometimes large amounts of cytokines or PGE2 after further stimulation with LPS. Although there was no direct correlation between production of cytokines or PGE2 and time postburn, the early increased production of PGE2 by splenic macrophages could have depressed the animal's ability to kill translocated bacteria by 24 hr postburn, and could be one of the mechanisms of the cause of systemic infection after burn injury.