Investigating associations between blood metabolites, later life brain imaging measures, and genetic risk for Alzheimer's disease

BACKGROUND

Identifying blood-based signatures of brain health and preclinical pathology may offer insights into early disease mechanisms and highlight avenues for intervention. Here, we systematically profiled associations between blood metabolites and whole-brain volume, hippocampal volume, and amyloid-β status among participants of Insight 46-the neuroscience sub-study of the National Survey of Health and Development (NSHD). We additionally explored whether key metabolites were associated with polygenic risk for Alzheimer's disease (AD).

METHODS

Following quality control, levels of 1019 metabolites-detected with liquid chromatography-mass spectrometry-were available for 1740 participants at age 60-64. Metabolite data were subsequently clustered into modules of co-expressed metabolites using weighted coexpression network analysis. Accompanying MRI and amyloid-PET imaging data were present for 437 participants (age 69-71). Regression analyses tested relationships between metabolite measures-modules and hub metabolites-and imaging outcomes. Hub metabolites were defined as metabolites that were highly connected within significant (p_FDR < 0.05) modules or were identified as a hub in a previous analysis on cognitive function in the same cohort. Regression models included adjustments for age, sex, APOE genotype, lipid medication use, childhood cognitive ability, and social factors. Finally, associations were tested between AD polygenic risk scores (PRS), including and excluding the APOE region, and metabolites and modules that significantly associated (p_FDR < 0.05) with an imaging outcome (N = 1638).

RESULTS

In the fully adjusted model, three lipid modules were associated with a brain volume measure (p_FDR < 0.05): one enriched in sphingolipids (hippocampal volume: ß = 0.14, 95% CI = [0.055,0.23]), one in several fatty acid pathways (whole-brain volume: ß =  - 0.072, 95%CI = [- 0.12, - 0.026]), and another in diacylglycerols and phosphatidylethanolamines (whole-brain volume: ß =  - 0.066, 95% CI = [- 0.11, - 0.020]). Twenty-two hub metabolites were associated (p_FDR < 0.05) with an imaging outcome (whole-brain volume: 22; hippocampal volume: 4). Some nominal associations were reported for amyloid-β, and with an AD PRS in our genetic analysis, but none survived multiple testing correction.

CONCLUSIONS

Our findings highlight key metabolites, with functions in membrane integrity and cell signalling, that associated with structural brain measures in later life. Future research should focus on replicating this work and interrogating causality.

First Report in Chile of Mycocentrospora acerina, Causal Agent of Peony (Paeonialactiflora) Red Spot

A survey to identify pathogens causing peony diseases in southern Chile (37°95' to 40°58'S) was conducted from 2008 to 2011. A noticeable symptom consisted of small red spots on leaves, stems, sepals, and first petals of the bud. The central part of the lesions (1 cm) enlarged, darkened, and became necrotic, coincident with rainy and cold weather, including frosts. Lesions grew but never coalesced completely. At the edges of leaves, the infected tissues cracked and produced a twisted and corrugated appearance. Rhizome symptoms were also observed and consisted of black spots, which enlarged to elongated lesions. Small pieces (~1 × 1 mm) of symptomatic leaves, previously washed with 2% NaOCl for 2 min were cultured on potato dextrose agar (PDA) and V8 juice agar (20%) media. The cultures were incubated in growth chambers at 20°C (dark) and 5°C (dark)/20°C (light) for 12/12 h (dark/light). Sporulation was obtained only with V8 under the dark and light regime. Mycelia growth was superficial and immersed in the media; hyphae were septate with thick black walls. Conidiophores were flexuous, not branched, and produced a single spore. Spores were elongate, multiseptate, with a long, strongly curved beak. After one week, sporulation decreased and thick-walled, round black clamydospores formed in the media. Spores ranged from 125 to 235 μm long and most frequently were 170 to 220 μm. The number of septa ranged from 5 to 12. Morphological and cultural characteristics fit the description of Mycocentrospora acerina (Harting) Deighton (1,2). DNA was obtained from fungal culture. The internal transcribed spacer (ITS) region was amplified using ITS1/ITS4 primers (3), and part of the amplicon (502 of 550 pb) was sequenced. The sequence was deposited in GeneBank (Accession No. KF015599) and showed 100% identity values with sequences of similar regions from M. acerina (strain ATCC 16259, Accession No. KF278454). Healthy leaves and rhizome pieces were washed with sterile distilled water and placed on sterile moist paper towel. A small agar disc with mycelium was placed on the leaves and rhizomes with and without wounding before inoculation. The inoculated materials were kept in closed boxes with high humidity at 5 to 20°C. Tests were positive in leaves and rhizomes with and without wounds. Seven days after leaf inoculations, necrotic symptoms developed. A second inoculation test in peony leaves of plants bagged with plastic under field conditions corroborated the in vitro test. Inoculated rhizomes developed dark orange lesions initially, then turned black with a watery consistency, similarly to affected rhizomes in the field. In both tests, controls showed no symptoms. To our knowledge, this is the first report of M. acerina on P. lactiflora globally (4). In an evaluation at Carillanca (38°41'S, 72°25'W), using a scale from 0 (no symptoms) to 7 (necrotic lesions covering >60% of foliage, with death of stems), 11 out of 31 peony varieties scored 0-1. As a reference, a score of 3 is the maximum damage allowed on peonies for export. These varieties might help to keep Chilean peonies in the market without an economic impact. References: (1) M. B. Ellis. Dematiaceous Hyphomycetes. CMI. Surrey, England, 1971. (2) B. C. Sutton and I. A. S Gibson. M. acerina. CMI. Descriptions of Pathogenic Fungi and Bacteria, No. 537.1977. (3) T. J. White et al. PCR Protocols. Academic Press, San Diego, CA, 1990. (4) D. F. Farr and A. Y. Rossman. Fungal Databases. Syst. Mycol. Microbiol. Lab., ARS, USDA. Retrieved April 16, 2014.

Developmental trajectories of disruptive behavior problems in preschool children of adolescent mothers

Using hierarchical linear modeling (HLM), we analyzed individual developmental trajectories of disruptive behavior problems between ages 3.5 to 6.0 years for 183 children of adolescent mothers. We examined how the level of problem behavior (intercept) and the rate of change over time (slope) are influenced by child's sex, mother's depression/anxiety symptoms, and mother's use of negative control for regulating child behavior. On average, disruptive behavior decreased from age 3.5 to 6.0. Child sex and maternal depression/anxiety related to the level of behavior problems but not to the rate of change. Boys and children of more depressed/anxious mothers exhibited higher levels of disruptive behavior. Maternal negative control was associated with both level of disruptive behavior and rate of change, and negative control mediated the effects of maternal depression/anxiety. Greater negative control corresponded to higher levels of behavior problems and no reduction in their display over time. Child race moderated effects of negative control.

Outcome of a controlled trial of the effectiveness of intensive case management for chronic public inebriates

OBJECTIVE

The objective of this study was to test whether an intensive case management intervention would be effective with a group of homeless chronic public inebriate clients. The primary goals of the case management were to improve the financial and residential stability of the clients and to reduce their use of alcohol.

METHOD

Subjects (N = 298, 81% male) were interviewed at baseline, randomly assigned to treatment and control conditions and given follow-up interviews at 6-month intervals for 2 years. Case management services were provided for the duration of the project. Follow-up rates for the first three interviews averaged 82%.

RESULTS

Repeated measures MANCOVAs showed significant group differences favoring the case-managed group in all three areas targeted by the intervention: total income from public sources, nights spent in "own place" out of the previous 60 nights and days drinking out of the previous 30 days. The results held whether the three variables were analyzed jointly or separately and for alternative measures of drinking and homelessness. Although statistically significant, the group differences are generally not large.

CONCLUSIONS

The results indicate that case management had a beneficial effect on the clients receiving it. This effect may have been the result of an increase in services received by the case-managed clients.

Substrate and hormonal responses during exercise classes at selected stages of pregnancy

This study examined the substrate and hormonal responses during exercise classes for 36 pregnant women at selected stages of pregnancy. Six nonpregnant women served as controls. Blood samples were obtained before exercise, at the end of aerobic exercise, and 45 min after aerobic exercise. All samples were analyzed for substrates (glucose, lactate, FFA) and 7 hormones. Heart rates in the pregnant women were approximately 150 bpm, although some were as high as 180 bpm. Heart rates in the control group were approximately 130 bpm. Modest increments occurred in lactate and FFA during exercise, and decrements in glucose were observed in all groups. Insulin concentrations decreased with exercise and remained depressed after exercise whereas FFA remained elevated postexercise in the pregnant women. Modest transient changes were observed with exercise in the other hormones. A severely blunted norepinephrine response to exercise was observed in the third-trimester group. In conclusion, uncontrolled non-steady-state exercise does not disrupt the substrate and endocrine milieu markedly. Recovery in hormonal and substrate concentrations appears to occur rapidly after exercise. However, decrements in blood glucose do occur for a short time during prenatal exercise classes, most notably for women in the third trimester.

Substance use and other factors associated with risky sexual behavior among pregnant adolescents

A study of the relationship between substance use and risky sexual behavior was conducted among 241 unmarried pregnant adolescents aged 17 and younger who lived in a metropolitan area in the Northwest. The respondents had comparable or higher lifetime use rates for all substances than did women in a national sample of high school seniors, even though the pregnant adolescents were younger. Ninety-four percent had used alcohol, 78% marijuana, 30% cocaine and 30% stimulants, compared with 92%, 48%, 14% and 23%, respectively, among women in the national sample. Among the pregnant adolescents, 84% had had more than one sexual partner, 39% had had a sexually transmitted disease and 60% had used contraceptives during less than half of their sexual encounters. At the bivariate level, use of cigarettes and alcohol in general and use of alcohol and drugs during sex were positively associated with risky sexual behavior. However, when other characteristics associated with risky sexual behavior--family bonding, parental monitoring, commitment to conventional values, peer associations, self-esteem and delinquent activities--were included in the multivariate analysis, the effect of substance use disappeared.

Substrate and endocrine responses during exercise at selected stages of pregnancy

To determine whether the concomitant effects of pregnancy and exercise yield substrate and endocrine patterns different from those expected during exercise alone, we compared the responses of glucose, lactate, free fatty acids, insulin, epinephrine (EP), norepinephrine (NE), human chorionic gonadotropin (HCG), human placental lactogen (HPL), estriol, and progesterone (P) in nonpregnant women (NP; n = 7) and pregnant women in the second (TR2; n = 6) and third trimester (TR3; n = 8) of pregnancy, before, during, and after 30 min of bicycle ergometer exercise at heart rates of 130-140 beats/min. In general, all substrates and hormone concentrations increased with exercise (P less than 0.05), except insulin, which decreased (P less than 0.05), and HCG, which did not change (P = 0.08). Differences in selected hormone concentrations (P, estriol, HCG, and HPL) among groups were already present at rest because of the different stages of pregnancy. Differences among groups at rest were also found in insulin and NE (P less than 0.05). Significantly different responses to exercise (i.e., group x time interactions) were as follows. NP vs. TR2:P, estriol, HCG, HPL, EP, and NE (P less than 0.05); NP vs. TR3: glucose, EP, and NE (P less than 0.05); TR2 vs. TR3: lactate, EP, and NE (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Is there a preferred coordinate system for perception of hand orientation in three-dimensional space?

The purpose of this experiment was to determine the preferred coordinate system for representation of hand orientation in 3-dimensional space. The ability of human subjects to perceive angles of the hand in 3-dimensional space (elevation, yaw, roll angles-extrinsic coordinate system) was compared to their ability to perceive hand angles relative to the proximal upper limb segments (wrist joint angles, forearm pronation-intrinsic coordinate system). With eyes closed, subjects performed a matching task in which the experimenter positioned the left arm, forearm and hand and the right arm and forearm. Subjects were then told to match an angle in one of the two coordinate systems by moving only the right hand at the wrist or the forearm as in pronation or roll matching. Absolute constant error (ACE), variable error (VE) and normalized variable error (NVE-normalized to tested range of motion) of matching were quantified for each subject for each of the six angles matched. It was hypothesized that matching angles in a preferred coordinate system would be associated with lower ACE, VE and NVE. Overall, ACE and VE were lower for matching hand angles in the intrinsic coordinate system. This suggests that the preferred coordinate system involved specification of hand angles relative to forearm and arm angles (joint angles) rather than the hand angles relative to axes external to the upper limb. However, matching of pronation angles was associated with larger VE and NVE than roll angle matching. There were no significant differences in ACE between pronation and roll matching. In a second experiment subjects with their forearms constrained at different elevations matched hand elevation and wrist flexion angles. Thus, errors in matching the angles in the non-preferred coordinate system were predictable if the subjects were biased toward matching angles in the preferred coordinate system. Trends in the data suggested that subjects preferred matching hand elevation angles but these trends were not consistent within or between subjects. Thus a preferred intrinsic coordinate system for wrist flexion matching was not observed in this experiment. We suggest that matching angles when proximal limb segments are constrained is a simpler task for the subjects (VE lower than in the first experiment) and may bias the matching toward the extrinsic coordinate system. Thus, hand orientation in 3-dimensional space may be perceived as follows: wrist flexion and abduction angles together with forearm elevation and yaw are used to specify hand elevation and yaw; these together with hand roll angle, completely specify the hand angle in 3-dimensional space.