Changes in folate, vitamin B12 and homocysteine associated with incident dementia

OBJECTIVES

Prospective findings have not been consistent for folate, vitamin B(12) and homocysteine concentrations as predictors of dementia. This study aimed to investigate both baseline concentrations of folate, vitamin B(12) and homocysteine and changes in these concentrations as predictors/correlates of incident dementia.

METHODS

Of 625 elderly patients without dementia at baseline, 518 (83%) were followed over a 2.4 year period and were clinically assessed for incident dementia and Alzheimer's disease (AD). Serum concentrations of folate, vitamin B(12) and homocysteine were measured at the baseline and follow-up assessments. Covariates included age, sex, education, disability, depression, alcohol consumption, physical activity, vascular risk factors, serum creatinine concentration, vitamin intake and weight change.

RESULTS

Only baseline lower folate concentrations predicted incident dementia. The onset of dementia was significantly associated with an exaggerated decline in folate, a weaker increase in vitamin B(12) concentrations and an exaggerated increase in homocysteine concentrations over the follow-up period. These associations were reduced following adjustment for weight change over the same period.

CONCLUSIONS

Incident dementia is more strongly associated with changes in folate, vitamin B(12) and homocysteine than with previous concentrations. These changes may be linked to other somatic manifestations of early dementia, such as weight loss.

Neuroimaging correlates of subjective memory deficits in a community population

BACKGROUND

Subjective memory deficit (SMD) is one of few potential presenting symptoms for people with early cognitive impairment. However, associations with underlying brain changes are unclear.

METHODS

In a community sample of 1,779 people without dementia, and with neuroimaging (MRI) data, associations were investigated for SMD with white matter lesion volume and with the following volumetric measures: gray and white matter, CSF, hippocampal, parahippocampal, and amygdalar. Covariates included depressive symptoms (Center for Epidemiologic Studies Depression Scale), a battery of cognitive tests, physical health, and social activity.

RESULTS

SMD was present in 26.4% of the sample. Of the neuroimaging measures analyzed, SMD was most strongly associated with temporal WML (OR for highest quintile compared to the remainder 1.44, 95% CI 1.12-1.85), and lower hippocampal volume (OR per decreasing quintile 1.22, 1.11-1.35). These associations were independent of all other covariates, including cognitive function.

CONCLUSIONS

Subjective memory deficit (SMD) was associated with neuroimaging characteristics in the temporal and hippocampal regions, suggesting that SMD may, at least in some cases, represent a realistic appraisal of underlying brain function independent of measured cognition. However, further research is required for volumetric measures and SMD to establish whether the association reflects lifelong structure or neurodegenerative changes.

Human hydration level monitoring using embedded piezoresistive microcantilever sensors

Embedded piezoresistive microcantilever (EPM) sensors were used to measure osmolality changes in both saliva mimic solutions and true human saliva. Osmolality changes in human saliva or urine may prove to be reliable, simple, and easy to measure markers for tracking human hydration levels. EPM sensors used in these experiments show good response to osmolality changes in both NaCl-based saliva mimic solutions and to human saliva. The addition of zero-point offset correction to EPM sensors allows for tracking of saliva osmolality changes with high accuracy. Also, the same EPM sensors exhibit a large enough range of osmolality response to make them potentially suitable for urine or blood serum osmolality monitoring.

Prevalence of depressive symptoms and syndromes in later life in ten European countries: the SHARE study

BACKGROUND

The EURO-D, a12-item self-report questionnaire for depression, was developed with the aim of facilitating cross-cultural research into late-life depression in Europe.

AIMS

To describe the national variation in depression symptoms and syndrome prevalence across ten European countries.

METHOD

The EURO-D was administered to cross-sectional nationally representative samples of non-institutionalised persons aged > or =50 years (n=22 777). The effects of age, gender, education and cognitive functioning on individual symptoms and EURO-D factor scores were estimated. Country-specific depression prevalence rates and mean factor scores were re-estimated, adjusted for these compositional effects.

RESULTS

The prevalence of all symptoms was higher in the Latin ethno-lingual group of countries, especially symptoms related to motivation. Women scored higher on affective suffering; older people and those with impaired verbal fluency scored higher on motivation.

CONCLUSIONS

The prevalence of individual EURO-D symptoms and of probable depression (cut-off score > or =4) varied consistently between countries. Standardising for effects of age, gender, education and cognitive function suggested that these compositional factors did not account for the observed variation.

Cloning and characterization of the sympathetic nervous system mutant, Sym3, in zebrafish

9541

Background: Neuroblastoma (NB) is a neural crest tumor manifesting in the adrenal gland and the sympathetic ganglia. The goal of this project was to use the zebrafish model to identify genes involved in the development of the peripheral sympathetic nervous system (PSNS). We used the expression of tyrosine hydroxylase (TH) in the cervical sympathetic ganglion (cervical complex, CC), as a marker for PSNS development. TH expression can be observed by whole-mount RNA in situ hybridization in 2–3-day zebrafish embryos in the CC. Methods: In an ethyl nitrosourea mutagenesis screen for mutations that affect PSNS development, we identified a putative mutant, Sym3, showing a change in modeling of the TH staining cells in the region of the CC. Results and Conclusion: The TH-positive cells were scattered rather than conglomerated together as is typical of cells in the normal CC. The mutant was also characterized by a “curly-tail” phenotype. After the mutation was recovered from the F3 generation, heterozygous pairs harboring the mutation were identified. Using genome wide scanning PCR assay, linkage of the Sym3 mutation to microsatellite markers z9704 and z1351, located on Linkage Group 1, was established. Complementation assays were performed with other known “curly tail” mutants in the genetic interval, which revealed that Sym3 and a previously described vic mutant were in the same complementation group. The vic mutant is characterized by curved body axis, left to right asymmetry and kidney cysts and results from a mutation in the ARL13b gene, a protein of the Ras superfamily involved in intracellular trafficking and cilial motility. The vic mutation is a C to A transition at position 104 in the second exon of the open reading frame (T35L). The ARL13b gene in Sym3 has a four aa insertion at the 5’ end of the 4th exon of the coding region.The mutant Sym3 phenotype can be rescued by overexpression of the normal ARL13b gene. The vic mutant showed defective cilia formation in the kidney. However, immunocytochemistry showed normal cilia in the Sym3 mutant, suggesting that the Sym3 allele of ARL13b affects the development of alternative tissues during development, such as the aggregation of sympathetic neurons into discrete ganglia. Further functional characterization of the Sym3 mutation is ongoing.

No significant financial relationships to disclose.

Kluyvera co-infection in two solid organ transplant recipients: an emerging pathogen or a colonizer bystander?

Kluyvera species are opportunistic, gram-negative bacilli in the family Enterobacteriaceae. Ordinarily occurring as a commensal, Kluyvera have been reported to cause serious infections in immunosuppressed and immunocompetent hosts, causing diarrhea, urinary infections, peritonitis, and cholecystitis. We report Kluyvera infections in 2 solid organ transplant recipients. An 18-year-old female with alpha-1 antitrypsin deficiency underwent living donor liver transplantation and presented 6 months later with a liver abscess. The abscess aspirate grew mixed organisms including Kluyvera cryocrescens. A 22-year-old female with renal failure secondary to focal segmental glomerulosclerosis underwent a deceased donor kidney transplant and presented 3 months later with pyelonephritis; the urine culture grew Kluyvera ascorbata. Both patients improved only when their antibiotic coverage was broadened to include Kluyvera. The isolation of Kluyvera as a pathogen in transplant patients emphasizes that this commensal organism may be virulent in this patient population.

Distributed situation awareness in dynamic systems: theoretical development and application of an ergonomics methodology

The purpose of this paper is to propose foundations for a theory of situation awareness based on the analysis of interactions between agents (i.e. both human and non-human) in subsystems. This approach may help to promote a better understanding of technology-mediated interaction in systems, as well as helping in the formulation of hypotheses and predictions concerning distributed situation awareness. It is proposed that agents within a system each hold their own situation awareness, which may be very different from (although compatible with) that of other agents. It is argued that we should not always hope for, or indeed want, sharing of this awareness, as different system agents have different purposes. This view marks situation awareness as a dynamic and collaborative process binding agents together on tasks on a moment-by-moment basis. Implications of this viewpoint for the development of a new theory of, and accompanying methodology for, distributed situation awareness are offered.