Describing the appropriate use and interpretation of odds and risk ratios.

In sport medicine, epidemiology of sport-related injury provides the foundation for understanding what types of injuries and illnesses occur and who is at the highest risk. Thus, accurate and transparent reporting and interpretation of risk metrics is essential to sports epidemiology. Odds ratios (OR) and risk ratios (RR) are two statistics used to quantify the association between exposure and outcome and are frequently seen in sports medicine literature. While similarities exist, there are optimal ways to use and interpret OR and RR based on the study design and outcome incidence in the target population. In this short communication, we will present common study designs (e.g. prospective cohort, case-control, cross-sectional) along with recommendations for the use and interpretation of OR and RR. This will ultimately assist practitioners in choosing and interpreting these frequently confused measures of association and also help journal reviewers better understand the appropriate use of these measures when evaluating a manuscript.

Genetic loss of D-amino acid oxidase activity reverses schizophrenia-like phenotypes in mice.

Reduced function of the N-methyl-d-aspartate receptor (NMDAR) has been implicated in the pathophysiology of schizophrenia. The NMDAR contains a glycine binding site in its NR1 subunit that may be a useful target for the treatment of schizophrenia. In this study, we assessed the therapeutic potential of long-term increases in the brain levels of the endogenous NMDAR glycine site agonist D-serine, through the genetic inactivation of its catabolic enzyme D-amino acid oxidase (DAO) in mice. The effects of eliminating DAO function were investigated in mice that display schizophrenia-related behavioral deficits due to a mutation (Grin 1(D481N)) in the NR1 subunit that results in a reduction in NMDAR glycine affinity. Grin 1(D481N) mice show deficits in sociability, prolonged latent inhibition, enhanced startle reactivity and impaired spatial memory. The hypofunctional Dao 1(G181R) mutation elevated brain levels of D-serine, but alone it did not affect performance in the behavioral measures. Compared to animals with only the Grin 1(D481N) mutation, mice with both the Dao1(G181R) and Grin 1(D481N) mutations displayed an improvement in social approach and spatial memory retention, as well as a reversal of abnormally persistent latent inhibition and a partial normalization of startle responses. Thus, an increased level of D-serine resulting from decreased catalysis corrected the performance of mice with deficient NMDAR glycine site activation in behavioral tasks relevant to the negative and cognitive symptoms of schizophrenia. Diminished DAO activity and elevations in D-serine may serve as an effective therapeutic intervention for the treatment of psychiatric symptoms.

Hypertension labelling was associated with poorer self-rated health in the Third US National Health and Nutrition Examination Survey.

Individuals labelled as having hypertension tend to report poor self-rated health (SRH), but it is unclear whether this association is independent of actual hypertension, socioeconomic status and adiposity, and extends across racial and ethnic groups. In a cross-sectional study we compared hypertensive and normotensive individuals (N = 19,057) who varied in whether they had ever been labelled hypertensive. Blood pressure was measured in participants' homes and mobile examination centres in the United States as part of the Third National Health and Nutrition Examination Survey, 1988-1994. The main outcome measure was global SRH. Hypertensive labelling was associated with poorer SRH and was independent of established SRH predictors, antihypertensive medication use, body mass index, and hypertension status (adjusted odds ratio (OR) = 1.79, 95% confidence interval (CI), 1.61-1.99). Hypertension was also associated with poorer SRH (OR = 1.26; 95% CI 1.09-1.46) but this association was eliminated by adjustment for hypertensive labelling (OR 1.06; 95% CI 0.92-1.22). These effects were consistent across non-Hispanic white, non-Hispanic black, and Hispanic subgroups. Individuals labelled hypertensive are more likely to have lower SRH and this labelling effect predominates over that of actual hypertension. Public health efforts to increase the number of individuals screened for high blood pressure may successfully detect the presence of hypertension but may also reduce health-related quality of life as measured by global SRH.

Pro-inflammatory and pro-oxidant properties of the HIV protein Tat in a microglial cell line: attenuation by 17 beta-estradiol.

Microglia are activated in humans following infection with human immunodeficiency virus (HIV), and brain inflammation is thought to be involved in neuronal injury and dysfunction during HIV infection. Numerous studies indicate a role for the HIV regulatory protein Tat in HIV-related inflammatory and neurodegenerative processes, although the specific effects of Tat on microglial activation, and the signal transduction mechanisms thereof, have not been elucidated. In the present study, we document the effects of Tat on microglial activation and characterize the signal transduction pathways responsible for Tat's pro-inflammatory effects. Application of Tat to N9 microglial cells increased multiple parameters of microglial activation, including superoxide production, phagocytosis, nitric oxide release and TNF alpha release. Tat also caused activation of both p42/p44 mitogen activated protein kinase (MAPK) and NF kappa B pathways. Inhibitor studies revealed that Tat-induced NF kappa B activation was responsible for increased nitrite release, while MAPK activation mediated superoxide release, TNF alpha release, and phagocytosis. Lastly, pre-treatment of microglial cells with physiological concentrations of 17 beta-estradiol suppressed Tat-mediated microglial activation by interfering with Tat-induced MAPK activation. Together, these data elucidate specific components of the microglial response to Tat and suggest that Tat could contribute to the neuropathology associated with HIV infection through microglial promulgation of oxidative stress.

Vitamin E suppression of microglial activation is neuroprotective.

Neurotoxic microglial-neuronal interactions have been implicated in the pathogenesis of various neurodegenerative diseases such as Alzheimer's disease, and vitamin E has been shown to have direct neuroprotective effects. To determine whether vitamin E also has indirect neuroprotective effects through suppression of microglial activation, we used a microglial-neuronal coculture. Lipopolysaccharide (LPS) treatment of a microglial cell line (N9) induced a time-dependent activation of both p38 mitogen-activated protein kinase (p38 MAPK) and nuclear factor-kappaB (NFkappaB), with consequent increases in interleukin-1alpha (IL-1alpha), tumor necrosis factor-alpha (TNF-alpha), and nitric oxide (NO) production. Differentiated neuronal cells (PC12 cells treated with nerve growth factor) exhibited marked loss of processes and decreased survival when cocultured with LPS-activated microglia. Preincubation of microglia with vitamin E diminished this neurotoxic effect, independently of direct effects of the antioxidant on the neuronal cells. Microglial NO production and the induction of IL-1alpha and TNFalpha expression also were attenuated by vitamin E. Such antiinflammatory effects of vitamin E were correlated with suppression of p38 MAPK and NFkappaB activation and were mimicked by an inhibition of either p38 MAPK (by SB203580) or NFkappaB (by decoy oligonucleotides). These results suggest that, in addition to the beneficial effects of providing direct antioxidant protection to neurons reported by others, vitamin E may provide neuroprotection in vivo through suppression of signaling events necessary for microglial activation.

Developing BSN leaders for the future: the Fuld Leadership Initiative for Nursing Education (LINE).

The Helene Fuld Leadership Initiative in Nursing Education (LINE) program was designed to enhance beginning leadership competencies of baccalaureate nursing students. Given the increasing need for strong and effective leadership throughout the health care system, and the demands new graduates encounter as they move into practice, the LINE program is built on the premise that leadership skills must be instilled at the undergraduate level. The program achieves its goal through an intensive 5-day institute focused on assessing and developing the leadership competencies of nurse educators and their clinical partners to enable them to be effective agents of curriculum change in their home institutions. The institute also assists participants to redesign their baccalaureate nursing (BSN) curricula to ensure that students learn to: (1) work effectively within and across complex, integrated organizational and institutional boundaries; (2) think and act from the perspective of a system; and (3) communicate, negotiate, lead, and facilitate change within health care organizations. D. Goleman's (1998) framework of emotional intelligence, which addresses both personal competence (managing oneself) and social competence (handling one's relationships with others) provides the framework for operationalizing leadership in the BSN curriculum. To date, 26 BSN programs and their clinical partners have participated in the LINE program, which has the potential to influence the beginning leadership development of more than 2,400 BSN students. Program outcomes reveal that education-practice collaboration, professional networking, individual leadership development of nurse educators and their clinical partners as change agents, and the integration of leadership experiences at all levels of the BSN curriculum are important in developing beginning leadership competencies in BSN students.

Activation of microglia by secreted amyloid precursor protein evokes release of glutamate by cystine exchange and attenuates synaptic function.

Microglial activation as part of a chronic inflammatory response is a prominent component of Alzheimer's disease. Secreted forms of the beta-amyloid precursor protein (sAPP) previously were found to activate microglia, elevating their neurotoxic potential. To explore neurotoxic mechanisms, we analyzed microglia-conditioned medium for agents that could activate glutamate receptors. Conditioned medium from primary rat microglia activated by sAPP caused a calcium elevation in hippocampal neurons, whereas medium from untreated microglia did not. This response was sensitive to the NMDA receptor antagonist, aminophosphonovaleric acid. Analysis of microglia-conditioned by HPLC revealed dramatically higher concentrations of glutamate in cultures exposed to sAPP. Indeed, the glutamate levels in sAPP-treated cultures were substantially higher than those in cultures treated with amyloid beta-peptide. This sAPP-evoked glutamate release was completely blocked by inhibition of the cystine-glutamate antiporter by alpha-aminoadipate or use of cystine-free medium. Furthermore, a sublethal concentration of sAPP compromised synaptic density in microglia-neuron cocultures, as evidenced by neuronal connectivity assay. Finally, the neurotoxicity evoked by sAPP in microglia-neuron cocultures was attenuated by inhibitors of either the neuronal nitric oxide synthase (N(G)-propyl-L-arginine) or inducible nitric oxide synthase (1400 W). Together, these data indicate a scenario by which microglia activated by sAPP release excitotoxic levels of glutamate, probably as a consequence of autoprotective antioxidant glutathione production within the microglia, ultimately causing synaptic degeneration and neuronal death.

Dehydroepiandrosterone inhibits microglial nitric oxide production in a stimulus-specific manner.

Dehydroepiandrosterone (DHEA) is a steroid that circulates in abundance in the form of a sulfated reserve (DHEA-S). The levels of DHEA decline with age and further in age-related neuropathologies, including Alzheimer disease. Because of their reported anti-inflammatory effects, we tested the actions of these compounds on microglia. At concentrations of 3(-9) to 1(-6) M, DHEA and DHEA-S inhibited the production of nitrite and morphological changes stimulated by lipopolysaccharide. DHEA and DHEA-S also inhibited LPS induction of iNOS protein, but neither inhibited LPS-induced iNOS mRNA or the activation of NF-kappaB. These data suggest that the hormone regulates nitrite production through a post-transcriptional mechanism. Interestingly, microglial nitrite production in response to a secreted form of the beta-amyloid precursor protein (sAPP) was unaffected by DHEA. Another Alzheimer-related factor, amyloid beta-peptide, also stimulated microglial nitrite production but in a manner dependent on the co-stimulus interferon-gamma. DHEA was found to inhibit only the interferon-gamma component of the microglial response. These data add to a growing body of evidence for differences in the profiles of mononuclear phagocytes activated by distinct stimuli.

Inflammation and Alzheimer's disease.

Inflammation clearly occurs in pathologically vulnerable regions of the Alzheimer's disease (AD) brain, and it does so with the full complexity of local peripheral inflammatory responses. In the periphery, degenerating tissue and the deposition of highly insoluble abnormal materials are classical stimulants of inflammation. Likewise, in the AD brain damaged neurons and neurites and highly insoluble amyloid beta peptide deposits and neurofibrillary tangles provide obvious stimuli for inflammation. Because these stimuli are discrete, microlocalized, and present from early preclinical to terminal stages of AD, local upregulation of complement, cytokines, acute phase reactants, and other inflammatory mediators is also discrete, microlocalized, and chronic. Cumulated over many years, direct and bystander damage from AD inflammatory mechanisms is likely to significantly exacerbate the very pathogenic processes that gave rise to it. Thus, animal models and clinical studies, although still in their infancy, strongly suggest that AD inflammation significantly contributes to AD pathogenesis. By better understanding AD inflammatory and immunoregulatory processes, it should be possible to develop anti-inflammatory approaches that may not cure AD but will likely help slow the progression or delay the onset of this devastating disorder.

Effects of lovastatin on cognitive function and psychological well-being.

PURPOSE: Animal research and cross-sectional studies suggest that serum lipid concentrations may influence cognitive function, mood, and behavior, but few clinical trials have studied these effects. SUBJECTS AND METHODS: In this double-blind investigation, 209 generally healthy adults with a serum low-density-lipoprotein (LDL) cholesterol level of 160 mg/dL or higher were randomly assigned to 6-month treatment with lovastatin (20 mg) or placebo. Assessments of neuropsychological performance, depression, hostility, and quality of life were conducted at baseline and at the end of the treatment period. Summary effect sizes were estimated as z scores on a standard deviation (SD) scale. RESULTS: Placebo-treated subjects improved between baseline and posttreatment periods on neuropsychological tests in all five performance domains, consistent with the effects of practice on test performance (all P <0.04), whereas those treated with lovastatin improved only on tests of memory recall (P = 0.03). Comparisons of the changes in performance between placebo- and lovastatin-treated subjects revealed small, but statistically significant, differences for tests of attention (z score = 0.18; 95% confidence interval (CI), 0.06 to 0.31; P = 0.005) and psychomotor speed (z score = 0.17; 95% CI, 0.05 to 0.28; P = 0. 004) that were consistent with greater improvement in the placebo group. Psychological well-being, as measured several ways, was not affected by lovastatin. CONCLUSION: Treatment of hypercholesterolemia with lovastatin did not cause psychological distress or substantially alter cognitive function. Treatment did result in small performance decrements on neuropsychological tests of attention and psychomotor speed, the clinical importance of which is uncertain.

S100beta induction of the proinflammatory cytokine interleukin-6 in neurons.

Levels of the neurotrophic cytokine S100beta and the proinflammatory cytokine interleukin-6 (IL-6) are both elevated in Alzheimer's brain, and both have been implicated in beta-amyloid plaque formation and progression. We used RT-PCR and electrophoretic mobility shift assay to assess S100beta induction of IL-6 expression and the role of kappaB-dependent transcription in this induction in neuron-enriched cultures and in neuron-glia mixed cultures from fetal rat cortex. S100beta (10 or 100 ng/ml x 24 h) increased IL-6 mRNA levels two- and fivefold, respectively (p<0.05 in each case), and S100beta (100-1,000 ng/ml) induced increases in medium levels of biologically active IL-6 (30-80%). Combined in situ hybridization and immunohistochemistry preparations localized IL-6 mRNA to neurons in these cultures. S100beta induction of IL-6 expression correlated with an increase in DNA binding activity specific for a KB element and was inhibited (75%) by suppression of kappaB binding with double-stranded "decoy" oligonucleotides. The low levels of S100beta required to induce IL-6 overexpression in neurons, shown here, suggest that overexpression of S100beta induces neuronal expression of IL-6 and of IL-6-induced neurodegenerative cascades in Alzheimer's disease.

Neuronal-glial interactions mediated by interleukin-1 enhance neuronal acetylcholinesterase activity and mRNA expression.

Cholinergic dysfunction in Alzheimer's disease has been attributed to stress-induced increases in acetylcholinesterase (AChE) activity. Interleukin-1 (IL-1) is overexpressed in Alzheimer's disease, and stress-related changes in long-term potentiation, an ACh-related cerebral function, are triggered by interleukin-1. Microglial cultures (N9) synthesized and released IL-1 in response to conditioned media obtained from glutamate-treated primary neuron cultures or PC12 cells. This conditioned media contained elevated levels of secreted beta-amyloid precursor protein (sAPP). Naive PC12 cells cocultured with stimulated N9 cultures showed increased AChE activity and mRNA expression. These effects on AChE expression and activity could be blocked by either preincubating the glutamate-treated PC12 supernatants with anti-sAPP antibodies or preincubating naive PC12 cells with IL-1 receptor antagonist. These findings were confirmed in vivo; IL-1-containing pellets implanted into rat cortex also increased AChE mRNA levels. Neuronal stress in Alzheimer's disease may induce increases in AChE expression and activity through a molecular cascade that is mediated by sAPP-induced microglial activation and consequent overexpression of IL-1.

Production and Functional Assays of Recombinant Secreted Amyloid Precursor Protein (APP) (sAPPα).

The ß-amyloid precursor protein (APP) is connected to Alzheimer's disease by both biochemistry and genetics. As the source of the major constituent of amyloid plaques, APP has been the subject of many studies of its expression and metabolism. The accumulation of amyloid ß-peptide (Aß) in these plaques was the first evidence that APP might be processed abnormally in Alzheimer's, and this idea was strengthened by the discovery of mutations in APP that segregate with the disease with high penetrance. Aberrant processing of APP was incorporated into the Amyloid Hypothesis, which supposes that the clinical symptoms, neuropathology, and ultimate fatality of Alzheimer's result from the actions of Aß. But to the extent that the Amyloid Hypothesis remains hypothetical, it would be irresponsible to ignore other theories that might explain the links between APP and Alzheimer's. APP can be proteolytically processed in a way that does not produce (and, in fact, precludes) Aß. This "α-secretase" event cleaves within the Aß sequence and liberates most of the extracellular portion (sAPPα) of APP from the cell surface Fig. 1). Because the "ß-secretase" event required for the generation of Aß creates a different soluble derivative (sAPPß), disease-related increases in ß-secretase processing -such as demonstrated with the "Swedish" mutation of APP-have the potential to affect events dependent on the normal function(s) of sAPPα. Furthermore, the increases in APP expression that occur as a result of injury or trisomy 21 may elevate the total levels of all sAPP species. To understand the implications of these events, it is critical to elucidate the biological activities of sAPPα and related moieties.

Inhibition of the activity of a neuronal kappaB-binding factor by glutamate.

Activation of transcription factors with affinity for kappaB enhancers is generally correlated with enhanced survival of neurons. In an apparent exception, excitotoxic concentrations of glutamate have been reported to elevate the activity of one such factor, nuclear factor-kappaB (NF-kappaB). Our data indicate that the constitutive neuronal kappaB-binding factor (NKBF) is distinct from bona fide NF-kappaB (RelA/p50 heterodimer). Therefore, we analyzed glutamate's effects on KB-binding activity in highly enriched primary neuronal cultures and in mixed neuron/glia cocultures. Electrophoretic mobility shift assays indicated that a 30-60-min exposure to 50-500 microM glutamate reduced NKBF activity by as much as 70%. Subtoxic doses of glutamate had little or no effect on this DNA-binding activity. Selective antagonists of either NMDA or AMPA [(RS)-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate]/kai nat e receptors inhibited the influence of glutamate on NKBF activity. The effect of glutamate was mimicked by calcium ionophore, and it was blocked by lowering extracellular calcium concentrations or by cyclosporin A. Bona fide NF-kappaB was found only in cocultures containing significant numbers of glia, where it could be activated by glutamate. These data suggest that the primary influence of excitatory amino acids on neuronal KB-binding activity is an inhibitory one, strengthening the correlation between this transcriptional parameter and neuronal survival.

Inhibition of AMPA responses by mutated presenilin 1.

The inheritance of Alzheimer's disease in some families, as well as ablation/rescue genetics in mice, suggest that point mutations in the presenilin-1 (PS1) gene can cause disease through an unknown gain-of-function. While mutations associated with familial Alzheimer's can alter apoptotic rates and beta-amyloid precursor processing, it is possible that other physiological effects contribute to pathogenesis. We have begun to explore effects on neurotransmission by monitoring responses of the neuropotent Ntera-2 cell line expressing wild-type PS1 or a FAD mutant thereof. Although no differences were initially apparent in calcium responses of metabotropic receptors, responses to glutamate were dampened in cells expressing the L286V mutant of PS1. Analysis of ionotropic agonists demonstrated that AMPA receptor alterations were responsible for this effect, whereas NMDA responses were unaltered. These data suggest that PS1 mutation could lead to cognitive deficits through subtoxic physiological effects.