Central trajectories of type II spiral ganglion neurons

Previous attempts to trace the central pathways of the thin axons from type II spiral ganglion neurons have been hampered by technical difficulties such as fading of the reaction product as distance increases from the injection site (Ryugo et al.: Soc. Neurosci. Abstr. 12:779, '86; Brown: J. Comp. Neurol. 260:591-604, '87). By using small rodents (gerbils and mice), which have short auditory nerves, we have succeeded in filling the entire central axon and terminals of type II neurons after peripheral injections of horseradish peroxidase. The general course of the type II fibers within the auditory nerve and cochlear nucleus is similar to that of type I fibers except that terminals from type II neurons are often found in regions of the cochlear nucleus that have high densities of granule cells.     

A block model of the cat cochlear nucleus.

A three-dimensional block model of the cochlear nucleus of the cat was constructed from histologic sections. Boundaries of various subdivisions, based on cytoarchitectonic criteria, were included in the model. Usage of the block model in correlating physiological and anatomical data is illustrated by localizing characteristic waveforms of gross evoked responses and characteristic frequencies of single units.     

Factors associated with presence and extent of coronary calcium in those predicted to be at low risk according to Framingham risk score (from the Multi-Ethnic Study of Atherosclerosis)

Even among asymptomatic persons at low risk (<10%) according to the Framingham risk score, high coronary artery calcium (CAC) scores signify a greater predicted risk of coronary heart disease events. We sought to determine the noninvasive factors (without radiation exposure) significantly associated with CAC in low-risk, asymptomatic persons. In a cross-sectional analysis, we studied 3,046 participants from the Multi-Ethnic Study of Atherosclerosis at a low 10-year predicted risk (Framingham risk score <10%) of coronary heart disease events. Multivariate logistic regression analysis was used to assess the association of novel markers with the presence of any CAC (CAC >0) and advanced CAC (CAC ≥ 300). A CAC level of >0 and of ≥ 300 was present in 30% and 3.5% of participants, respectively. Factor VIIIc, fibrinogen, and soluble intercellular adhesion molecule were each associated with the presence of CAC (p ≤ 0.02), and C-reactive protein, D-dimer, and the carotid intima-media thickness with advanced CAC (p ≤ 0.03). The base model combining the traditional risk factors had excellent discrimination for advanced CAC (C-statistic 0.808). The addition of the 2 best-fit models combining the biomarkers with or without carotid intima-media thickness improved the c-statistic to 0.822 and 0.820, respectively. All 3 models calibrated well but were similar in estimating the individual risk probabilities for advanced CAC (prevalence 9.97%, 10.63%, and 10.10% in the greatest quartiles of predicted probabilities vs 0.26%, 0.26%, and 0.26% in the lowest quartiles, respectively). In conclusion, in low-risk persons, the traditional risk factors alone predicted advanced CAC with high discrimination and calibration. The biomarker combinations with and without carotid intima-media thickness were also significantly associated with advanced CAC; however, the improvement in the prediction and estimation of the clinical risk were modest compared to the traditional risk factors alone.     

Modeling multisystem biological risk in young adults: The Coronary Artery Risk Development in Young Adults Study

Although much prior research has focused on identifying the roles of major regulatory systems in health risks, the concept of allostatic load (AL) focuses on the importance of a more multisystems view of health risks. How best to operationalize allostatic load, however, remains the subject of some debate. We sought to test a hypothesized metafactor model of allostatic load composed of a number of biological system factors, and to investigate model invariance across sex and ethnicity. Biological data from 782 men and women, aged 32–47, from the Oakland, CA and Chicago, IL sites of the Coronary Artery Risk Development in Young Adults Study (CARDIA) were collected as part of the Year 15exam in 2000. These include measures of blood pressure, metabolic parameters (glucose, insulin, lipid profiles, and waist circumference), markers of inflammation (interleukin‐6, C‐reactive protein, and fibrinogen), heart rate variability, sympathetic nervous system activity (12‐hr urinary norepinephrine and epinephrine) and hypothalamic‐pituitary‐adrenal axis activity (diurnal salivary free cortisol). A “metafactor” model of AL as an aggregate measure of six underlying latent biological subfactors was found to fit the data, with the metafactor structure capturing 84% of variance of all pairwise associations among biological subsystems. There was little evidence of model variance across sex and/or ethnicity. These analyses extend work operationalizing AL as a multisystems index of biological dysregulation, providing initial support for a model of AL as a metaconstruct of inter‐relationships among multiple biological regulatory systems, that varies little across sex or ethnicity. Am. J. Hum. Biol. 2010. © 2009 Wiley‐Liss, Inc.