The mediating role of socioeconomic status on the relationship between pregnancy history and later-life cognition.

OBJECTIVE: The association of pregnancy with later-life cognition is not well understood. We examined whether full-term and incomplete pregnancies were associated with cognition in a sample of postmenopausal women, and whether socioeconomic status (SES) factors mediated these relationships. METHODS: A total of 1016 cognitively normal women from the National Health and Nutrition Examination Survey (NHANES) were examined. Cognitive measures included the Digit Symbol Substitution Test (DSST), Animal Fluency (AF) and the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) Word Learning (CERAD-WL) and Delayed Recall (CERAD-DR) tasks. Analyses examined the relationship between the number of term and incomplete pregnancies with cognitive performance, as well as the mediating effects of education and the federal income-to-poverty ratio (PIR). RESULTS: A greater number of term pregnancies was associated with worse performance on the DSST (ß = -0.09, 95% confidence interval [CI]: -0.12, -0.06), AF (ß = -0.03, 95% CI: -0.07, 0.00) and CERAD-DR (ß = -0.04, 95% CI: -0.08, -0.01). More incomplete pregnancies were associated with better CERAD-DR performance (ß = 0.07, 95% CI: 0.01, 0.13), and 28% (95% CI: 0.17, 0.42) of the association of term pregnancies with the DSST was mediated by the PIR. CONCLUSIONS: A higher number of term pregnancies was associated with worse cognitive performance, whereas a higher number of incomplete pregnancies was associated with better cognitive performance. Results indicate the necessity to consider SES factors when studying the relationship between pregnancy and cognition.

Sex differences in the medial temporal lobe during encoding and recognition of pseudowords and abstract designs.

Sex differences in various cognitive abilities have been demonstrated in terms of performance differentials and, more recently, in differences in activation patterns during fMRI. Hemispheric lateralization is sometimes accentuated in sex differences; e.g., women demonstrating greater activation of the left hemisphere than men during verbal tasks. We were interested in whether this phenomenon applies to memory for words and designs (i.e., material specific memory). Using analogous verbal (pseudowords) and nonverbal (abstract designs) encoding and recognition tasks completed back-to-back in a 3T scanner, we found that women tend to show exaggerated left hippocampal activation during certain stages of encoding and recognition of verbal information, compared with men. Likewise (although to a lesser extent), men showed more right hippocampal activation than women did during the abstract design learning task. These results have important implications for the generalization of fMRI memory study results, for example to clinical populations such as patients undergoing epilepsy surgery.

Infection rates, disease frequency, pilin gene rearrangement, and pilin expression in calves inoculated with Moraxella bovis pilin-specific isogenic variants.

Pili have been implicated as virulence factors that result in increased infectivity of Moraxella bovis, the causative agent of infectious bovine keratoconjunctivitis (IBK). Healthy calves' eyes were inoculated with I- or Q-piliate or nonpiliate M bovis Epp63 to compare the pathogenicity of these isogenic variants. Pathogenicity was determined by the rate of persistent M bovis infection and the prevalence of clinical IBK. Inoculation with M bovis expressing the Q pili resulted in the highest frequency of infection and IBK, whereas I-piliate M bovis elicited a lower rate and nonpiliate M bovis did not result in infection. In vivo pilin gene rearrangement and pilin-type switching were evaluated by DNA hybridization and immunoblot. Gene rearrangement and type switching varied dependently, and were observed only in eyes inoculated with Q-piliate M bovis. This study suggests that Q pili are specific for colonization of bovine corneal epithelium, whereas I pili enable maintenance of an established infection.

Diffusion measures indicate fight exposure-related damage to cerebral white matter in boxers and mixed martial arts fighters.

BACKGROUND AND PURPOSE: Traumatic brain injury is common in fighting athletes such as boxers, given the frequency of blows to the head. Because DTI is sensitive to microstructural changes in white matter, this technique is often used to investigate white matter integrity in patients with traumatic brain injury. We hypothesized that previous fight exposure would predict DTI abnormalities in fighting athletes after controlling for individual variation. MATERIALS AND METHODS: A total of 74 boxers and 81 mixed martial arts fighters were included in the analysis and scanned by use of DTI. Individual information and data on fight exposures, including number of fights and knockouts, were collected. A multiple hierarchical linear regression model was used in region-of-interest analysis to test the hypothesis that fight-related exposure could predict DTI values separately in boxers and mixed martial arts fighters. Age, weight, and years of education were controlled to ensure that these factors would not account for the hypothesized effects. RESULTS: We found that the number of knockouts among boxers predicted increased longitudinal diffusivity and transversal diffusivity in white matter and subcortical gray matter regions, including corpus callosum, isthmus cingulate, pericalcarine, precuneus, and amygdala, leading to increased mean diffusivity and decreased fractional anisotropy in the corresponding regions. The mixed martial arts fighters had increased transversal diffusivity in the posterior cingulate. The number of fights did not predict any DTI measures in either group. CONCLUSIONS: These findings suggest that the history of fight exposure in a fighter population can be used to predict microstructural brain damage.

Effects of dexmedetomidine, a novel imidazole sedative-anesthetic agent, on adrenal steroidogenesis: in vivo and in vitro studies.

Inhibition of steroidogenesis may be produced perioperatively by imidazole compounds, such as the hypnotic agent etomidate, with potentially serious consequences for patient morbidity and mortality. Dexmedetomidine, ([+]4-[1-[2,3-dimethylphenyl]-ethyl]-1H-imidazole), another imidazole compound with anesthetic like properties, is now being used perioperatively. Therefore, we investigated the effects of dexmedetomidine on steroidogenesis as well as on binding to glucocorticoid receptors in a series of in vitro and in vivo animal studies. The effect of dexmedetomidine, 10(-8)-10(-3) M, on adrenocorticotrophic hormone (ACTH) stimulated release of corticosterone was assessed in isolated rat adrenal cells. To characterize dexmedetomidine interactions with the glucocorticoid receptor, dexmedetomidine's ability to compete for [3H]dexmethasone binding sites was studied in renal tubular cells. The effect of dexmedetomidine, 80 micrograms/kg subcutaneously, on ACTH-stimulated release of cortisol was studied in separate cohorts of dogs at various time intervals during and after anesthesia was given. To compare the inhibitory effects of etomidate and dexmedetomidine on steroidogenesis, ACTH-stimulated release of cortisol was studied in dogs treated with anesthetic doses of either dexmedetomidine (80 micrograms/kg IV) or etomidate (1 mg/kg IV). Finally, dogs were given dexmedetomidine by continuous subcutaneous infusion for 7 days at sedative doses after which their cortisol response to ACTH was determined. At dexmedetomidine concentrations greater than 10(-7) M, a dose-dependent inhibition of corticosterone release was detected in response to ACTH stimulation in vitro. At these high dexmedetomidine concentrations, [3H]dexamethasone binding was not affected. In the in vivo dog experiments, basal cortisol levels decreased and the cortisol response to ACTH was blunted 3 h after dexmedetomidine administration.(ABSTRACT TRUNCATED AT 250 WORDS)