Comparison of histological delineations of medial temporal lobe cortices by four independent neuroanatomy laboratories

The medial temporal lobe (MTL) cortex, located adjacent to the hippocampus, is crucial for memory and prone to the accumulation of certain neuropathologies such as Alzheimer's disease neurofibrillary tau tangles. The MTL cortex is composed of several subregions which differ in their functional and cytoarchitectonic features. As neuroanatomical schools rely on different cytoarchitectonic definitions of these subregions, it is unclear to what extent their delineations of MTL cortex subregions overlap. Here, we provide an overview of cytoarchitectonic definitions of the entorhinal and parahippocampal cortices as well as Brodmann areas (BA) 35 and 36, as provided by four neuroanatomists from different laboratories, aiming to identify the rationale for overlapping and diverging delineations. Nissl-stained series were acquired from the temporal lobes of three human specimens (two right and one left hemisphere). Slices (50 μm thick) were prepared perpendicular to the long axis of the hippocampus spanning the entire longitudinal extent of the MTL cortex. Four neuroanatomists annotated MTL cortex subregions on digitized slices spaced 5 mm apart (pixel size 0.4 μm at 20× magnification). Parcellations, terminology, and border placement were compared among neuroanatomists. Cytoarchitectonic features of each subregion are described in detail. Qualitative analysis of the annotations showed higher agreement in the definitions of the entorhinal cortex and BA35, while the definitions of BA36 and the parahippocampal cortex exhibited less overlap among neuroanatomists. The degree of overlap of cytoarchitectonic definitions was partially reflected in the neuroanatomists' agreement on the respective delineations. Lower agreement in annotations was observed in transitional zones between structures where seminal cytoarchitectonic features are expressed less saliently. The results highlight that definitions and parcellations of the MTL cortex differ among neuroanatomical schools and thereby increase understanding of why these differences may arise. This work sets a crucial foundation to further advance anatomically-informed neuroimaging research on the human MTL cortex.

Longitudinal volumetric changes in amygdala subregions in frontotemporal dementia

Amygdala atrophy has been found in frontotemporal dementia (FTD), yet the specific changes of its subregions across different FTD phenotypes remain unclear. The aim of this study was to investigate the volumetric alterations of the amygdala subregions in FTD phenotypes and how they evolve with disease progression. Patients clinically diagnosed with behavioral variant FTD (bvFTD) (n = 20), semantic dementia (SD) (n = 20), primary nonfluent aphasia (PNFA) (n = 20), Alzheimer's disease (AD) (n = 20), and 20 matched healthy controls underwent whole brain structural MRI. The patient groups were followed up annually for up to 3.5 years. Amygdala nuclei were segmented using FreeSurfer, corrected by total intracranial volumes, and grouped into the basolateral, superficial, and centromedial subregions. Linear mixed effects models were applied to identify changes in amygdala subregional volumes over time. At baseline, bvFTD, SD, and AD displayed global amygdala volume reduction, whereas amygdala volume appeared to be preserved in PNFA. Asymmetrical amygdala atrophy (left > right) was most pronounced in SD. Longitudinally, SD and PNFA showed greater rates of annual decline in the right basolateral and superficial subregions compared to bvFTD and AD. The findings provide comprehensive insights into the differential impact of FTD pathology on amygdala subregions, revealing distinct atrophy patterns that evolve over disease progression. The characterization of amygdala subregional involvement in FTD and their potential role as biomarkers carry substantial clinical implications.

Exploring graded profiles of hippocampal atrophy along the anterior-posterior axis in semantic dementia and Alzheimer's disease

Mounting evidence indicates marked hippocampal degeneration in semantic dementia (SD) however, the spatial distribution of hippocampal atrophy profiles in this syndrome remains unclear. Using a recently developed parcellation approach, we extracted hippocampal volumes from four distinct subregions running from anterior to posterior along the longitudinal axis (anterior, intermediate rostral, intermediate caudal, and posterior). Volumetric differences in hippocampal subregions were compared between 21 SD, 24 matched Alzheimer's disease (AD), and 27 healthy older Control participants. Despite comparable overall hippocampal volume loss, SD and AD groups diverged in terms of the magnitude of atrophy along the anterior-posterior axis of the hippocampus. Global hippocampal atrophy was observed in AD, with no discernible gradation or lateralisation. In contrast, SD patients displayed graded bilateral hippocampal atrophy, most pronounced on the left-hand side, and concentrated in anterior relative to posterior subregions. Finally, we found preliminary evidence that disease-specific vulnerability along the anterior-posterior axis of the hippocampus was associated with canonical clinical features of these syndromes.

Comparison of histological delineations of medial temporal lobe cortices by four independent neuroanatomy laboratories

The medial temporal lobe (MTL) cortex, located adjacent to the hippocampus, is crucial for memory and prone to the accumulation of certain neuropathologies such as Alzheimer's disease neurofibrillary tau tangles. The MTL cortex is composed of several subregions which differ in their functional and cytoarchitectonic features. As neuroanatomical schools rely on different cytoarchitectonic definitions of these subregions, it is unclear to what extent their delineations of MTL cortex subregions overlap. Here, we provide an overview of cytoarchitectonic definitions of the cortices that make up the parahippocampal gyrus (entorhinal and parahippocampal cortices) and the adjacent Brodmann areas (BA) 35 and 36, as provided by four neuroanatomists from different laboratories, aiming to identify the rationale for overlapping and diverging delineations. Nissl-stained series were acquired from the temporal lobes of three human specimens (two right and one left hemisphere). Slices (50 µm thick) were prepared perpendicular to the long axis of the hippocampus spanning the entire longitudinal extent of the MTL cortex. Four neuroanatomists annotated MTL cortex subregions on digitized (20X resolution) slices with 5 mm spacing. Parcellations, terminology, and border placement were compared among neuroanatomists. Cytoarchitectonic features of each subregion are described in detail. Qualitative analysis of the annotations showed higher agreement in the definitions of the entorhinal cortex and BA35, while definitions of BA36 and the parahippocampal cortex exhibited less overlap among neuroanatomists. The degree of overlap of cytoarchitectonic definitions was partially reflected in the neuroanatomists' agreement on the respective delineations. Lower agreement in annotations was observed in transitional zones between structures where seminal cytoarchitectonic features are expressed more gradually. The results highlight that definitions and parcellations of the MTL cortex differ among neuroanatomical schools and thereby increase understanding of why these differences may arise. This work sets a crucial foundation to further advance anatomically-informed human neuroimaging research on the MTL cortex.

Posterior hippocampal CA2/3 volume is associated with autobiographical memory recall ability in lower performing individuals

People vary substantially in their capacity to recall past experiences, known as autobiographical memories. Here we investigated whether the volumes of specific hippocampal subfields were associated with autobiographical memory retrieval ability. We manually segmented the full length of the two hippocampi in 201 healthy young adults into DG/CA4, CA2/3, CA1, subiculum, pre/parasubiculum and uncus, in the largest such manually segmented subfield sample yet reported. Across the group we found no evidence for an association between any subfield volume and autobiographical memory recall ability. However, when participants were assigned to lower and higher performing groups based on their memory recall scores, we found that bilateral CA2/3 volume was significantly and positively associated with autobiographical memory recall performance specifically in the lower performing group. We further observed that this effect was attributable to posterior CA2/3. By contrast, semantic details from autobiographical memories, and performance on a range of laboratory-based memory tests, did not correlate with CA2/3 volume. Overall, our findings highlight that posterior CA2/3 may be particularly pertinent for autobiographical memory recall. They also reveal that there may not be direct one-to-one mapping of posterior CA2/3 volume with autobiographical memory ability, with size mattering perhaps only in those with poorer memory recall.

New insights into anatomical connectivity along the anterior–posterior axis of the human hippocampus using in vivo quantitative fibre tracking

The hippocampus supports multiple cognitive functions including episodic memory. Recent work has highlighted functional differences along the anterior–posterior axis of the human hippocampus, but the neuroanatomical underpinnings of these differences remain unclear. We leveraged track-density imaging to systematically examine anatomical connectivity between the cortical mantle and the anterior–posterior axis of the in vivo human hippocampus. We first identified the most highly connected cortical areas and detailed the degree to which they preferentially connect along the anterior–posterior axis of the hippocampus. Then, using a tractography pipeline specifically tailored to measure the location and density of streamline endpoints within the hippocampus, we characterised where these cortical areas preferentially connect within the hippocampus. Our results provide new and detailed insights into how specific regions along the anterior–posterior axis of the hippocampus are associated with different cortical inputs/outputs and provide evidence that both gradients and circumscribed areas of dense extrinsic anatomical connectivity exist within the human hippocampus. These findings inform conceptual debates in the field and emphasise the importance of considering the hippocampus as a heterogeneous structure. Overall, our results represent a major advance in our ability to map the anatomical connectivity of the human hippocampus in vivo and inform our understanding of the neural architecture of hippocampal-dependent memory systems in the human brain.

The brain allows us to perceive and interact with our environment and to create and recall memories about our day-to-day lives. A sea-horse shaped structure in the brain, called the hippocampus, is critical for translating our perceptions into memories, and it does so in coordination with other brain regions. For example, different regions of the cerebral cortex (the outer layer of the brain) support different aspects of cognition, and pathways of information flow between the cerebral cortex and hippocampus underpin the healthy functioning of memory.

Decades of research conducted into the brains of non-human primates show that specific regions of the cerebral cortex anatomically connect with different parts of the hippocampus to support this information flow. These insights form the foundation for existing theoretical models of how networks of neurons in the hippocampus and the cerebral cortex are connected. However, the human cerebral cortex has greatly expanded during our evolution, meaning that patterns of connectivity in the human brain may diverge from those in the brains of non-human primates.

Deciphering human brain circuits in greater detail is crucial if we are to gain a better understanding of the structure and operation of the healthy human brain. However, obtaining comprehensive maps of anatomical connections between the hippocampus and cerebral cortex has been hampered by technical limitations. For example, magnetic resonance imaging (MRI), an approach that can be used to study the living human brain, suffers from insufficient image resolution.

To overcome these issues, Dalton et al. used an imaging technique called diffusion weighted imaging which is used to study white matter pathways in the brain. They developed a tailored approach to create high-resolution maps showing how the hippocampus anatomically connects with the cerebral cortex in the healthy human brain. Dalton et al. produced detailed maps illustrating which areas of the cerebral cortex have high anatomical connectivity with the hippocampus and how different parts of the hippocampus preferentially connect to different neural circuits in the cortex. For example, the experiments demonstrate that highly connected areas in a cortical region called the temporal cortex connect to very specific, circumscribed regions within the hippocampus.

These findings suggest that the hippocampus may consist of different neural circuits, each preferentially linked to defined areas of the cortex which are, in turn, associated with specific aspects of cognition. These observations further our knowledge of hippocampal-dependant memory circuits in the human brain and provide a foundation for the study of memory decline in aging and neurodegenerative diseases.

Autologous skin-derived neural precursor cell therapy reverses canine Alzheimer dementia-like syndrome in a proof of concept veterinary trial

BACKGROUND

Older companion dogs naturally develop a dementia-like syndrome with biological, clinical and therapeutic similarities to Alzheimer disease (AD). Given there has been no new safe, clinically effective and widely accessible treatment for AD for almost 20 years, an all-new cell therapeutic approach was trialled in canine veterinary patients, and further modelled in aged rats for more detailed neurobiological analysis.

METHODS

A Phase 1/2A veterinary trial was conducted in N = 6 older companion dogs with definitive diagnosis of Canine Cognitive Dysfunction (CCD). Treatment comprised direct microinjection of 250,000 autologous skin-derived neuroprecursors (SKNs) into the bilateral hippocampus using MRI-guided stereotaxis. Safety was assessed clinically and efficacy using the validated Canine Cognitive Dysfunction Rating Scale (CCDR) at baseline and 3-month post treatment. Intention to treat analysis imputed a single patient that had a surgical adverse event requiring euthanasia. Three dog brains were donated following natural death and histology carried out to quantify Alzheimer pathology as well as immature neurons and synapses; these were compared to a brain bank (N = 12) of untreated aged dogs with and without CCD. Further, an age-related memory dysfunction rat model (N = 16) was used to more closely evaluate intrahippocampal engraftment of canine SKN cells, focusing on mnemonic and synaptic effects as well as donor cell survival, neurodifferentation and electrophysiologic circuit integration in a live hippocampal slice preparation.

RESULTS

Four out-of-five dogs improved on the primary clinical CCDR endpoint, three fell below diagnostic threshold, and remarkably, two underwent full syndromal reversal lasting up to 2 years. At post mortem, synaptic density in the hippocampus specifically was nine standard deviations above non-treated dogs, and intensity of new neurons also several fold higher. There was no impact on AD pathology or long-term safety signals. Modelling in aged rats replicated the main canine trial findings: hippocampally-dependent place memory deficits were reversed and synaptic depletion rescued. In addition, this model confirmed donor cell survival and migration throughout the hippocampus, neuronal differentiation in situ, and physiologically-correct integration into pyramidal layer circuits.

CONCLUSIONS

With further development, SKN cell therapy may have potential for treating carefully chosen AD patients based on neurosynaptic restoration in the hippocampus.

Characterising the hippocampal response to perception, construction and complexity

The precise role played by the hippocampus in supporting cognitive functions such as episodic memory and future thinking is debated, but there is general agreement that it involves constructing representations comprised of numerous elements. Visual scenes have been deployed extensively in cognitive neuroscience because they are paradigmatic multi-element stimuli. However, questions remain about the specificity and nature of the hippocampal response to scenes. Here, we devised a paradigm in which we had participants search pairs of images for either colour or layout differences, thought to be associated with perceptual or spatial constructive processes respectively. Importantly, images depicted either naturalistic scenes or phase-scrambled versions of the same scenes, and were either simple or complex. Using this paradigm during functional MRI scanning, we addressed three questions: 1. Is the hippocampus recruited specifically during scene processing? 2. If the hippocampus is more active in response to scenes, does searching for colour or layout differences influence its activation? 3. Does the complexity of the scenes affect its response? We found that, compared to phase-scrambled versions of the scenes, the hippocampus was more responsive to scene stimuli. Moreover, a clear anatomical distinction was evident, with colour detection in scenes engaging the posterior hippocampus whereas layout detection in scenes recruited the anterior hippocampus. The complexity of the scenes did not influence hippocampal activity. These findings seem to align with perspectives that propose the hippocampus is especially attuned to scenes, and its involvement occurs irrespective of the cognitive process or the complexity of the scenes.

The Role of Hippocampal-Ventromedial Prefrontal Cortex Neural Dynamics in Building Mental Representations

The hippocampus and ventromedial prefrontal cortex (vmPFC) play key roles in numerous cognitive domains including mind-wandering, episodic memory, and imagining the future. Perspectives differ on precisely how they support these diverse functions, but there is general agreement that it involves constructing representations composed of numerous elements. Visual scenes have been deployed extensively in cognitive neuroscience because they are paradigmatic multielement stimuli. However, it remains unclear whether scenes, rather than other types of multifeature stimuli, preferentially engage hippocampus and vmPFC. Here, we leveraged the high temporal resolution of magnetoencephalography to test participants as they gradually built scene imagery from three successive auditorily presented object descriptions and an imagined 3-D space. This was contrasted with constructing mental images of nonscene arrays that were composed of three objects and an imagined 2-D space. The scene and array stimuli were, therefore, highly matched, and this paradigm permitted a closer examination of step-by-step mental construction than has been undertaken previously. We observed modulation of theta power in our two regions of interest-anterior hippocampus during the initial stage and vmPFC during the first two stages, of scene relative to array construction. Moreover, the scene-specific anterior hippocampal activity during the first construction stage was driven by the vmPFC, with mutual entrainment between the two brain regions thereafter. These findings suggest that hippocampal and vmPFC neural activity is especially tuned to scene representations during the earliest stage of their formation, with implications for theories of how these brain areas enable cognitive functions such as episodic memory.

Manipulating the temporal locus and content of mind-wandering

The human brain has a tendency to drift into the realm of internally-generated thoughts that are unbound by space and time. The term mind-wandering (MW) is often used describe such thoughts when they are perceptually decoupled. Evidence suggests that exposure to forward and backward illusory motion skews the temporal orientation of MW thoughts to either the future or past respectively. However, little is known about the impact of this manipulation on other features of MW. Here, using a novel experimental paradigm, we first confirmed that our illusory motion method facilitated the generation of MW thoughts congruent with the direction of motion. We then conducted content analyses which revealed that goal orientation and temporal distance were also significantly affected by the direction of illusory motion. We conclude that illusory motion may be an effective means of assaying MW and could help to elucidate this ubiquitous, and likely critical, component of cognition.

Functional connectivity along the anterior-posterior axis of hippocampal subfields in the ageing human brain

While age‐related volumetric changes in human hippocampal subfields have been reported, little is known about patterns of subfield functional connectivity (FC) in the context of healthy ageing. Here we investigated age‐related changes in patterns of FC down the anterior–posterior axis of each subfield. Using high resolution structural MRI we delineated the dentate gyrus (DG), CA fields (including separating DG from CA3), the subiculum, pre/parasubiculum, and the uncus in healthy young and older adults. We then used high resolution resting state functional MRI to measure FC in each group and to directly compare them. We first examined the FC of each subfield in its entirety, in terms of FC with other subfields and with neighboring cortical regions, namely, entorhinal, perirhinal, posterior parahippocampal, and retrosplenial cortices. Next, we analyzed subfield to subfield FC within different portions along the hippocampal anterior–posterior axis, and FC of each subfield portion with the neighboring cortical regions of interest. In general, the FC of the older adults was similar to that observed in the younger adults. We found that, as in the young group, the older group displayed intrinsic FC between the subfields that aligned with the tri‐synaptic circuit but also extended beyond it, and that FC between the subfields and neighboring cortical areas differed markedly along the anterior–posterior axis of each subfield. We observed only one significant difference between the young and older groups. Compared to the young group, the older participants had significantly reduced FC between the anterior CA1‐subiculum transition region and the transentorhinal cortex, two brain regions known to be disproportionately affected during the early stages of age‐related tau accumulation. Overall, these results contribute to ongoing efforts to characterize human hippocampal subfield connectivity, with implications for understanding hippocampal function and its modulation in the ageing brain.

Differences in functional connectivity along the anterior-posterior axis of human hippocampal subfields

There is a paucity of information about how human hippocampal subfields are functionally connected to each other and to neighbouring extra-hippocampal cortices. In particular, little is known about whether patterns of functional connectivity (FC) differ down the anterior-posterior axis of each subfield. Here, using high resolution structural MRI we delineated the hippocampal subfields in healthy young adults. This included the CA fields, separating DG/CA4 from CA3, separating the pre/parasubiculum from the subiculum, and also segmenting the uncus. We then used high resolution resting state functional MRI to interrogate FC. We first analysed the FC of each hippocampal subfield in its entirety, in terms of FC with other subfields and with the neighbouring regions, namely entorhinal, perirhinal, posterior parahippocampal and retrosplenial cortices. Next, we analysed FC for different portions of each hippocampal subfield along its anterior-posterior axis, in terms of FC between different parts of a subfield, FC with other subfield portions, and FC of each subfield portion with the neighbouring cortical regions of interest. We found that intrinsic functional connectivity between the subfields aligned generally with the tri-synaptic circuit but also extended beyond it. Our findings also revealed that patterns of functional connectivity between the subfields and neighbouring cortical areas differed markedly along the anterior-posterior axis of each hippocampal subfield. Overall, these results contribute to ongoing efforts to characterise human hippocampal subfield connectivity, with implications for understanding hippocampal function.

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High resolution resting state functional MRI scans were collected.

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We investigated functional connectivity (FC) of human hippocampal subfields.

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We specifically examined FC along the anterior-posterior axis of subfields.

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FC between subfields extended beyond the canonical tri-synaptic circuit.

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Different portions of subfields showed different patterns of FC with neocortex.

Differentiable Processing of Objects, Associations, and Scenes within the Hippocampus

The hippocampus is known to be important for a range of cognitive functions, including episodic memory, spatial navigation, and thinking about the future. However, researchers have found it difficult to agree on the exact nature of this brain structure's contribution to cognition. Some theories emphasize the role of the hippocampus in associative processes. Another theory proposes that scene construction is its primary role. To directly compare these accounts of hippocampal function in human males and females, we devised a novel mental imagery paradigm where different tasks were closely matched for associative processing and mental construction, but either did or did not evoke scene representations, and we combined this with high-resolution functional MRI. The results were striking in showing that different parts of the hippocampus, along with distinct cortical regions, were recruited for scene construction or nonscene-evoking associative processing. The contrasting patterns of neural engagement could not be accounted for by differences in eye movements, mnemonic processing, or the phenomenology of mental imagery. These results inform conceptual debates in the field by showing that the hippocampus does not seem to favor one type of process over another; it is not a story of exclusivity. Rather, there may be different circuits within the hippocampus, each associated with different cortical inputs, which become engaged depending on the nature of the stimuli and the task at hand. Overall, our findings emphasize the importance of considering the hippocampus as a heterogeneous structure, and that a focus on characterizing how specific portions of the hippocampus interact with other brain regions may promote a better understanding of its role in cognition.SIGNIFICANCE STATEMENT The hippocampus is known to be important for a range of cognitive functions, including episodic memory, spatial navigation, and thinking about the future. However, researchers have found it difficult to agree on the exact nature of this brain structure's contribution to cognition. Here we used a novel mental imagery paradigm and high-resolution functional MRI to compare accounts of hippocampal function that emphasize associative processes with a theory that proposes scene construction as a primary role. The results were striking in showing that different parts of the hippocampus, along with distinct cortical regions, were recruited for scene construction or nonscene-evoking associative processing. We conclude that a greater emphasis on characterizing how specific portions of the hippocampus interact with other brain regions may promote a better understanding of its role in cognition.

The pre/parasubiculum: a hippocampal hub for scene-based cognition?

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We consider internal representations of the world in the form of scenes.

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The anterior medial hippocampus is implicated in scene-based cognition.

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This region contains the pre/parasubiculum.

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The pre/parasubiculum is a primary target of a major visuospatial processing system.

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The pre/parasubiculum may be the hippocampal hub of the scene processing network.

Internal representations of the world in the form of spatially coherent scenes have been linked with cognitive functions including episodic memory, navigation and imagining the future. In human neuroimaging studies, a specific hippocampal subregion, the pre/parasubiculum, is consistently engaged during scene-based cognition. Here we review recent evidence to consider why this might be the case. We note that the pre/parasubiculum is a primary target of the parieto-medial temporal processing pathway, it receives integrated information from foveal and peripheral visual inputs and it is contiguous with the retrosplenial cortex. We discuss why these factors might indicate that the pre/parasubiculum has privileged access to holistic representations of the environment and could be neuroanatomically determined to preferentially process scenes.

Segmenting subregions of the human hippocampus on structural magnetic resonance image scans: An illustrated tutorial

BACKGROUND

The hippocampus plays a central role in cognition, and understanding the specific contributions of its subregions will likely be key to explaining its wide-ranging functions. However, delineating substructures within the human hippocampus in vivo from magnetic resonance image scans is fraught with difficulties. To our knowledge, the extant literature contains only brief descriptions of segmentation procedures used to delineate hippocampal subregions in magnetic resonance imaging/functional magnetic resonance imaging studies.

METHODS

Consequently, here we provide a clear, step-by-step and fully illustrated guide to segmenting hippocampal subregions along the entire length of the human hippocampus on 3T magnetic resonance images.

RESULTS

We give a detailed description of how to segment the hippocampus into the following six subregions: dentate gyrus/Cornu Ammonis 4, CA3/2, CA1, subiculum, pre/parasubiculum and the uncus. Importantly, this in-depth protocol incorporates the most recent cyto- and chemo-architectural evidence and includes a series of comprehensive figures which compare slices of histologically stained tissue with equivalent 3T images.

CONCLUSION

As hippocampal subregion segmentation is an evolving field of research, we do not suggest this protocol is definitive or final. Rather, we present a fully explained and expedient method of manual segmentation which remains faithful to our current understanding of human hippocampal neuroanatomy. We hope that this 'tutorial'-style guide, which can be followed by experts and non-experts alike, will be a practical resource for clinical and research scientists with an interest in the human hippocampus.

Isolation and Expansion of Adult Canine Hippocampal Neural Precursors

The rate of neurogenesis within the adult hippocampus has been shown to vary across mammalian species. The canine hippocampus, demonstrating a structural intermediacy between the rodent and human hippocampi, is therefore a valuable model in which to study adult neurogenesis. In vitro culture assays are an essential component of characterizing neurogenesis and adult neural precursor cells, allowing for precise control over the cellular environment. To date however, culture protocols for canine cells remain under-represented in the literature. Detailed here are systematic protocols for the isolation and culture of hippocampal neural precursor cells from the adult canine brain. We demonstrate the expansion of canine neural precursor cells as floating neurospheres and as an adherent monolayer culture, producing stable cell lines that are able to differentiation into mature neural cell types in vitro. Adult canine neural precursors are an underused resource that may provide a more faithful analogue for the study of human neural precursors and the cellular mechanisms of adult neurogenesis.

Material specific lateralization of medial temporal lobe function: An fMRI investigation

The theory of material specific lateralization of memory function posits that left and right MTL regions are asymmetrically involved in mnemonic processing of verbal and nonverbal material respectively. Lesion and functional imaging (fMRI) studies provide robust evidence for a left MTL asymmetry in the verbal memory domain. Evidence for a right MTL/nonverbal asymmetry is not as robust. A handful of fMRI studies have investigated this issue but have generally utilised nonverbal stimuli which are amenable to semantic elaboration. This fMRI study aimed to investigate the neural correlates of recognition memory processing in 20 healthy young adults (mean age = 26 years) for verbal stimuli and nonverbal stimuli that were specifically designed to minimize verbalisation. Analyses revealed that the neural correlates of recognition memory processing for verbal and nonverbal stimuli were differentiable and asymmetrically recruited the left and right MTL respectively. The right perirhinal cortex and hippocampus were preferentially involved in successful recognition memory of items devoid of semantic information. In contrast, the left anterior hippocampus was preferentially involved in successful recognition memory of stimuli which contained semantic meaning. These results suggest that the left MTL is preferentially involved in mnemonic processing of verbal/semantic information. In contrast, the right MTL is preferentially involved in visual/non-semantic mnemonic processing. We propose that during development, the left MTL becomes specialised for verbal mnemonic processing due to its proximity with left lateralised cortical language processing areas while visual/non-semantic mnemonic processing gets 'crowded out' to become predominantly, but not completely, the domain of the right MTL.

Variation in access to sugar-sweetened beverages in vending machines across rural, town and urban high schools

OBJECTIVES

The 2010 Dietary Guidelines for Americans include reducing consumption of sugar-sweetened beverages. Among the many possible routes of access for youth, school vending machines provide ready availability of sugar-sweetened beverages. The purpose of this study was to determine variation in high school student access to sugar-sweetened beverages through vending machines by geographic location - urban, town or rural - and to offer an approach for analysing school vending machine content.

STUDY DESIGN

Cross-sectional observational study.

METHODS

Between October 2007 and May 2008, trained coders recorded beverage vending machine content and machine-front advertising in 113 machines across 26 schools in New Hampshire and Vermont, USA.

RESULTS

Compared with town schools, urban schools were significantly less likely to offer sugar-sweetened beverages (P = 0.002). Rural schools also offered more sugar-sweetened beverages than urban schools, but this difference was not significant. Advertisements for sugar-sweetened beverages were highly prevalent in town schools.

CONCLUSIONS

High school students have ready access to sugar-sweetened beverages through their school vending machines. Town schools offer the highest risk of exposure; school vending machines located in towns offer up to twice as much access to sugar-sweetened beverages in both content and advertising compared with urban locations. Variation by geographic region suggests that healthier environments are possible and some schools can lead as inspirational role models.

Impaired acquisition rates of probabilistic associative learning in frontotemporal dementia is associated with fronto-striatal atrophy

Frontotemporal dementia (FTD) is classically considered to be a neurodegenerative disease with cortical changes. Recent structural imaging findings, however, highlight that subcortical and in particular striatal regions are also affected in the FTD syndrome. The influence of striatal pathology on cognitive and behavioural changes in FTD is virtually unexplored. In the current study we employ the Weather Prediction Task (WPT), a probabilistic learning task which taps into striatal dysfunction, in a group of FTD patients. We also regressed the patients' behavioural performance with their grey matter atrophy via voxel-based morphometry (VBM) to identify the grey matter contributions to WPT performance in FTD. Based on previous studies we expected to see striatal and frontal atrophy to be involved in impaired probabilistic learning. Our behavioural results show that patients performed on a similar level to controls overall, however, there was a large variability of patient performance in the first 30 trials of the task, which are critical in the acquisition of the probabilistic learning rules. A VBM analysis covarying the performance for the first 30 trials across participants showed that atrophy in striatal but also frontal brain regions correlated with WPT performance in these trials. Closer inspection of performance across the first 30 trials revealed a subgroup of FTD patients that performed significantly poorly than the remaining patients and controls on the WPT, despite achieving the same level of probabilistic learning as the other groups in later trials. Additional VBM analyses revealed that the subgroup of FTD patients with poor early probabilistic learning in the first 30 trials showed greater striatal atrophy compared to the remaining FTD patients and controls. These findings suggest that the integrity of fronto-striatal regions is important for probabilistic learning in FTD, with striatal integrity in particular, determining the acquisition learning rate. These findings will therefore have implications for developing an easily administered version of the probabilistic learning task which can be used by clinicians to assess striatal functioning in neurodegenerative syndromes.

Multiple biological pathways link cognitive lifestyle to protection from dementia

BACKGROUND

An active cognitive lifestyle is linked to diminished dementia risk, but the underlying mechanisms are poorly understood. Potential mechanisms include disease modification, neuroprotection, and compensation. Prospective, population-based brain series provide the rare opportunity to test the plausibility of these mechanisms in humans.

METHODS

Participants came from the United Kingdom Medical Research Council Cognitive Function and Ageing Study, comprising 13,004 individuals aged over 65 years and followed for 14 years. In study 1, a Cognitive Lifestyle Score (CLS) was computed on all Cognitive Function and Ageing Study subjects to define low, middle, and high groups. By August 2004, 329 individuals with CLS data had come to autopsy and underwent Consortium to Establish a Registry of Alzheimer's Disease assessment. Study 2 involved more detailed quantitative histology in the hippocampus and Brodmann area 9 in 72 clinically matched individuals with high and low CLS.

RESULTS

CLS groups did not differ on several Alzheimer disease neuropathologic measures; however, high CLS men had less cerebrovascular disease after accounting for vascular risk factors, and women had greater brain weight. No group differences were evident in hippocampal neuronal density. In Brodmann area 9, cognitively active individuals had significantly greater neuronal density, as well as correlated increases in cortical thickness.

CONCLUSIONS

An active cognitive lifestyle was associated with protection from cerebrovascular disease in men, but there was no evidence for Alzheimer disease modification or hippocampal neuroprotection. Men and women both exhibited neurotrophic changes in the prefrontal lobe linked to cognitive lifestyle, consistent with a compensatory process. Lifespan complex cognitive activity may therefore protect against dementia through multiple biological pathways.

Children with a TV in their bedroom at higher risk for being overweight

OBJECTIVE

We examined having a TV in the bedroom as a risk factor for child overweight.

DESIGN

Cross-sectional study.

SETTING

School- and telephone-based surveys in New Hampshire and Vermont between 2002 and 2004.

PARTICIPANTS

Two thousand three hundred and forty-three children enrolled in public schools, aged 9-12 years, and one of their parents.

MAIN EXPOSURES

The child having a TV in the bedroom.

MAIN OUTCOME MEASURES

Age- and gender-standardized child body mass index (zBMI). Overweight was defined as equal to or above the 95th percentile for zBMI.

RESULTS

Overall, 22.3% (N=523) of the children were overweight, and almost half of all children (48.2%, N=1130) had a TV in their bedroom. Children with a TV in their bedroom had a higher zBMI and were significantly more likely to be overweight compared to those without a TV in their bedroom (27.3 versus 17.7%, respectively; P<0.05). After controlling for sociodemographics, physical activity, frequency of TV or movie watching and internet use, children with a TV in their bedroom who watched at least one session of TV or movies per day were more likely to be overweight compared to those without a TV in their bedroom (odds ratio=1.32, 95% confidence interval: 1.03, 1.70).

CONCLUSIONS

Having a TV in the bedroom is a risk factor for child overweight, independent of reported physical activity, participation in team sports, TV or movie watching time and internet use at home. Further study is needed to fully understand the mechanism by which having a TV in the bedroom increases children's risk for overweight.

Effect of seeing tobacco use in films on trying smoking among adolescents: cross sectional study

OBJECTIVE

To test the hypothesis that greater exposure to smoking in films is associated with trying smoking among adolescents.

DESIGN

Cross sectional survey of 4919 schoolchildren aged 9-15 years, and assessment of occurrence of smoking in 601 films.

SETTING

Randomly selected middle schools in Vermont and New Hampshire, USA.

MAIN OUTCOME MEASURE

Number of schoolchildren who had ever tried smoking a cigarette.

RESULTS

The films contained a median of 5 (interquartile range 1-12) occurrences of smoking. The typical adolescent had seen 17 of 50 films listed. Exposure to smoking in films varied widely: median 91 (49-152) occurrences. The prevalence of ever trying smoking increased with higher categories of exposure: 4.9% among students who saw 0-50 occurrences of smoking, 13.7% for 51-100 occurrences, 22.1% for 101-150, and 31.3% for >150. The association remained significant after adjustment for age; sex; school performance; school; parents' education; smoking by friend, sibling, or parent; and receptivity to tobacco promotions. The adjusted odds ratios of ever trying smoking for students in the higher categories of exposure, compared with students exposed to 0-50 occurrences of smoking in films, were 1.7 (95% confidence interval 1.2 to 2.4), 2.4 (1.7 to 3.4), and 2.7 (2.0 to 3.8). These odds ratios were not substantially affected by adjustment for parenting style or for personality traits of the adolescent.

CONCLUSION

In this sample of adolescents there was a strong, direct, and independent association between seeing tobacco use in films and trying cigarettes, a finding that supports the hypothesis that smoking in films has a role in the initiation of smoking in adolescents.

Favourite movie stars, their tobacco use in contemporary movies, and its association with adolescent smoking

OBJECTIVE

To assess the relation between adolescents' favourite movie stars, the portrayal of tobacco use by those stars in contemporary motion pictures, and adolescent smoking.

DESIGN AND SETTING

632 students (sixth to 12th grade, ages 10-19 years) from five rural New England public schools completed a voluntary, self administered survey in October 1996. The survey assessed tobacco use, other variables associated with adolescent smoking, and favourite movie star. In addition, tobacco use by 43 selected movie stars was measured in films between 1994 and 1996.

OUTCOME MEASURES

Students were categorised into an ordinal five point index (tobacco status) based on their smoking behaviour and their smoking susceptibility: non-susceptible never smokers, susceptible never smokers, non-current experimenters, current experimenters, and smokers. We determined the adjusted cumulative odds of having advanced smoking status based on the amount of on-screen tobacco use by their favourite film star.

RESULTS

Of the 43 stars, 65% used tobacco at least once, and 42% portrayed smoking as an essential character trait in one or more films. Stars who smoked more than twice in a film were considered smokers. For adolescents whose favourite stars smoked in only one film, the odds of being higher on the smoking index was 0.78 (95% confidence interval (CI) 0.53 to 1.15). For adolescents whose favourite stars smoked in two films, the odds of being higher on the smoking index was 1.5 (95% CI 1.01 to 2.32). For adolescents whose favourite stars smoked in three or more films (Leonardo DiCaprio, Sharon Stone, John Travolta), the odds of being higher on the smoking index was 3.1 (95% CI 1.34 to 7.12). Among never smokers (n = 281), those who chose stars who were smokers in three or more films were much more likely to have favourable attitudes toward smoking (adjusted odds ratio 16.2, 95% CI 2.3 to 112).

CONCLUSIONS

Adolescents who choose movie stars who use tobacco on-screen are significantly more likely to have an advanced smoking status and more favourable attitudes toward smoking than adolescents who choose non-smoking stars. This finding supports the proposition that the portrayal of tobacco use in contemporary motion pictures, particularly by stars who are admired by adolescents, contributes to adolescent smoking.

Brand appearances in contemporary cinema films and contribution to global marketing of cigarettes

BACKGROUND

The appearance of a cigarette brand in a cinema film gives the brand a certain distinction through its association with the characters and general tone of the film. Through the worldwide distribution of films, brands are promoted globally. We assessed the tobacco-brand appearances in a 10-year sample of contemporary films.

METHODS

We viewed the contents of the top 25 US box-office films for each year of release, from 1988 to 1997 (250 films in total). We compared the prevalence of brand appearances for films produced before a voluntary ban on paid product placement by the tobacco industry (1988-90) with films produced after the ban (1991-97). Tobacco-brand appearance was defined as the screen appearance of a brand name, logo, or identifiable trademark on products or product packaging, billboards, store-front advertising, or tobacco promotional items. We defined actor endorsement of a brand as the display of a brand while being handled or used by an actor.

FINDINGS

More than 85% of the films contained tobacco use. Tobacco brands appeared in 70 (28%) films. Brand appearances were as common in films suitable for adolescent audiences as they were in films for adult audiences (32 vs 35%), and were also present in 20% of those rated for children. Prevalence of brand appearance did not change overall in relation to the ban. However, there was a striking increase in the type of brand appearance depicted, with actor endorsement increasing from 1% of films before the ban to 11% after. Four US cigarette brands accounted for 80% of brand appearances. Revenues outside the USA accounted for 49% of total revenues for these films, indicating a large international audience.

INTERPRETATION

Tobacco-brand appearances are common in films and are becoming increasingly endorsed by actors. The most highly advertised US cigarette brands account for most brand appearances, which suggests an advertising motive to this practice.

E-mail communication between medical students and schoolchildren: A model for medical education

OBJECTIVE

To examine e-mail communication between student physicians and schoolchildren, in the context of a school-based tobacco prevention program, as a way to teach communication skills and model physician-patient interactions.

DESIGN

Twenty medical students and pediatric residents were partnered with groups of children as part of HealthQuest, a tobacco prevention program implemented in 2 kindergarten through grade 12 Vermont schools. Medical students and residents acted as mentors for their group and provided support to the schoolchildren through e-mail and occasional site visits. E-mail messages were transmitted and stored in a Web server and monitored by preceptors. Content analysis of the messages was performed to identify emerging themes.

RESULTS

During the 2-year intervention period, 1187 messages were exchanged between children, teachers, and the student physicians. Thirty-two percent (n = 383) of the messages involved tobacco, of which 54% addressed health effects; 23% were related to social influences of tobacco use, 15% to cessation by parents and others, and 7% to cessation by students. Other categories included nontobacco health issues (n = 135), personal questions (n = 294), and classroom information (n = 735). Many inquiries required medical students and residents to research their answers, and several required collaboration with preceptors, because the questions raised serious medical or psychosocial issues. With feedback, medical students and residents adjusted their responses so that they were appropriate for the developmental level of the children.

CONCLUSIONS

The e-mail component of this program provided important learning opportunities for student physicians in tobacco control, child development, communication skills, and developing a physician-patient relationship. This model also offers potential benefits for medically underserved pediatric populations. Arch Pediatr Adolesc Med. 2000;154:1258-1262.

Positive and negative outcome expectations of smoking: implications for prevention

BACKGROUND

To inform the development of messages for tobacco prevention programs, we examined seven positive and five negative outcome expectations of smoking as risk factors for smoking uptake.

METHODS

A cross-sectional, self-administered survey of 471 students in grades 6-12 who were never or experimental smokers was performed. Logistic regression was used to examine the relationship between outcome expectations and susceptibility to becoming a smoker in the future, a measure of intent and resistance to peer smoking.

RESULTS

A total of 36.1% of the sample was susceptible to smoking. All positive outcome expectations showed a strong and significant association with susceptibility. Students were most likely to be susceptible if they believed they would enjoy smoking (OR = 29.4). Three of the five negative outcome expectations were significantly associated with susceptibility, but the strength of these associations was much lower than that observed for the positive expectations (OR = 0.5 to 0.6). A strong belief in the negative outcomes of smoking did not alter the association between susceptibility and positive outcome expectations.

CONCLUSIONS

These findings suggest that teaching adolescents and teens about the negative consequences of smoking is unlikely to change their intent to smoke. Preventive efforts should identify ways to address the positive expectations adolescents have about smoking, possibly by offering alternative means for achieving these outcomes.

Randomized trial of calcium glycerophosphate-supplemented infant formula to prevent lead absorption

BACKGROUND

Although additional dietary calcium is recommended frequently to reduce the risk of lead poisoning, its role in preventing lead absorption has not been evaluated clinically.

OBJECTIVE

The objective was to determine the safety and to estimate the size of the effect of calcium- and phosphorus-supplemented infant formula in preventing lead absorption.

DESIGN

One hundred three infants aged 3.5-6 mo were randomly assigned to receive iron-fortified infant formula (465 mg Ca and 317 mg P/L) or the same formula with added calcium glycerophosphate (1800 mg Ca and 1390 mg P/L) for 9 mo.

RESULTS

There was no significant difference between groups in the mean ratio of urinary calcium to creatinine, serum calcium and phosphorus, or change in iron status (serum ferritin, total iron binding capacity). At month 4, the median (+/-SD) increase from baseline in blood lead concentration for the supplemented group was 57% of the increase for the control group (0.04 +/- 0.09 compared with 0.07 +/- 0.10 micromol/L; P = 0.039). This effect was attenuated during the latter half of the trial, with an overall median increase in blood lead concentration from baseline to month 9 of 0.12 +/- 0.13 micromol/L for the control group and 0.10 +/- 0.18 micromol/L for the supplemented group (P = 0.284).

CONCLUSIONS

Supplementation did not have a measurable effect on urinary calcium excretion, calcium homeostasis, or iron status. The significant effect on blood lead concentrations during the first 4 mo was in the direction expected; however, because this was not sustained throughout the 9-mo period we cannot conclude that the calcium glycerophosphate supplement prevented lead absorption in this population.

Cigarette promotional items in public schools

OBJECTIVES

To assess the prevalence of ownership of cigarette promotional items (CPIs) by rural northern New England students and to examine the association between CPI ownership and smoking behavior.

DESIGN AND SETTING

Voluntary, self-administered survey of 1265 sixth- through 12th-grade students representing 79% to 95% of all students attending 5 rural New Hampshire and Vermont public schools in October 1996. We examined the association between ownership of a CPI and smoking behavior through regression models and conducted a sensitivity analysis on the findings.

MAIN OUTCOME MEASURES

Adjusted odds of being a smoker (lifetime use of > or = 100 cigarettes) and, among never smokers and experimental smokers, adjusted cumulative odds of having higher levels of smoking uptake given CPI ownership.

RESULTS

One third of students owned a CPI. Prevalence of ownership did not vary by grade or sex, but was higher among poor-to-average school performers (45.0% vs 21.0% for excellent school performers, P < .001) and children whose friends and family members smoked (43.4% vs 13.8% for students with no family members or friends smoking, P < .001). Cigarette promotional items included articles of clothing (T-shirts, hats, backpacks, and jackets), smoking paraphernalia (lighters and ashtrays), camping gear, and electronics. More than half of CPIs (58.2%) bore the Marlboro logo, and almost one third (31.7%) bore the Camel logo. These items were obtained directly from catalogs or vendors 22.4% of the time. Whereas only 4.5% of students reported bringing a CPI to school with them the day of the survey, 44.5% reported seeing such an item at school the day of the survey. After controlling for confounding factors, such as having friends who smoke, students who owned CPIs were 4.1 times more likely to be smokers than those who did not own CPIs (95% confidence interval [CI], 3.1-5.5). Never and experimental smokers (n = 1008) who owned CPIs were more likely to be in a higher category on the smoking uptake index in grades 6 (cumulative odds ratio [OR = 5.7, 95% CI, 1.9-16.8), 7 (OR = 1.8, 95% CI, 0.9-3.7), 8 (OR = 2.3, 95% CI, 1.1-4.8), and 9 (OR = 2.1, 95% CI, 1.1-3.9), periods when children are most vulnerable to initiating cigarette use. A sensitivity analysis indicated that an unmeasured confounder of CPI ownership and smoking was unlikely to alter our conclusions.

CONCLUSIONS

Cigarette promotional items are owned by one third of students in these rural northern New England schools. These items are highly visible in the public school setting, and their ownership is strongly associated with initiation and maintenance of smoking behavior. These data lend support to a ban on CPIs to be included in US Food and Drug Administration regulations to prevent tobacco use among US youth.

Calcium and phosphorus supplementation of iron-fortified infant formula: no effect on iron status of healthy full-term infants

One objective of this clinical trial was to determine whether calcium and phosphorus supplementation of infant formula affects the iron status of healthy full-term infants. One hundred three infants were randomly assigned to receive iron-fortified, cow milk-based infant formula (465 mg Ca and 317 mg P/L) or the same formula with added calcium glycerophosphate (1800 mg Ca and 1390 mg P/L) for 9 mo. Reported calcium intake for supplemented infants was about four times that of control infants, ranging from a mean of 1741 mg/d at baseline to 1563 mg/d at 9 mo. There was no difference by treatment group in mean or median change from baseline of serum ferritin, total-iron-binding capacity, erythrocyte protoporphyrin, or hematocrit at 4 and 9 mo after enrollment. Incidence of iron deficiency was similar for both groups and no infant developed iron deficiency anemia during the trial. This study indicates that the well-documented inhibitory effect of calcium and phosphorus on iron absorption is not clinically important in infants fed iron-fortified infant formula.

Census tract analysis of lead exposure in Rhode Island children

There has been increasing interest in a targeted approach to the screening and prevention of lead exposure in children. Targeted screening requires an understanding of variation in lead exposure in individual children or by region. In order to better understand variation by region, we studied Rhode Island lead poisoning screening data, examining average lead exposure to children living in 136 Providence County census tracts (CTs). The study population included 17,956 children aged 59 months and under, who were screened between May 1, 1992, and April 30, 1993. We evaluated the relationship between the percentage of children with blood lead > or = 10 micrograms/dL (pe10) and sociodemographic and housing characteristics, derived from United States 1990 Census data, of these CTs. CT descriptors included population density, percentage of households receiving public assistance income, median per capita income, percentage of households female headed, percentage of houses owner occupied, percentage of houses built before 1950, percentage of houses vacant, percentage of population Black, percentage of recent immigrants, and intraurban mobility. On average, 109 children were screened in each census tract; mean screening rate was 44%. There was wide variation in average lead exposure among census tracts, with pe10 ranging from 3 to 60% of screened children (mean 27%). Individual census variables explained between 24 and 67% of the variance in pe10 among CTs. A multiple regression model including percentage screened, percentage of households receiving public assistance, percentage of houses built before 1950, In (percentage of houses vacant), and percentage of recent immigrants explained 83% of variance in pe10. The percentage of houses built before 1950, a variable which models the presence of lead paint in old houses, displayed the largest adjusted effect on pe10 over the range observed for that variable in RI CTs. The percentage of houses vacant was also a highly significant and robust predictor; we suggest that vacancy is an ecological marker for the deterioration of leadbased paint, with higher vacancy neighborhoods containing houses in poorer condition. In Rhode Island, census tracts with high vacancy rates also have high rates of recent immigration, making immigrant groups vulnerable to lead exposure. Small-areas analysis may be useful in directing resources to high risk areas, explaining the sociocultural forces which produce such exposure and analyzing the effects of housing policy over time in states with high screening penetration.

Rethinking the threshold for an abnormal capillary blood lead screening test

OBJECTIVES

To examine the test characteristics of the capillary blood lead screening test as a predictor of elevated venous blood lead levels, using receiver operating characteristic (ROC) curves. To consider a rational capillary blood lead cutoff value in the context of what has been learned about the screening test and what is understood about the clinical course of children with elevated blood lead levels in the mild range (0.48-0.92 mumol/L [10-19 micrograms/dL]).

DESIGN

In a clinical trial, 513 urban children aged 6 years and younger were screened for lead exposure. Paired samples of venous blood were drawn from all children. For these children we examine the ROC curves for capillary blood lead levels as a predictor of elevated venous blood lead levels above 2 thresholds, 0.48 and 0.97 mumol/L (10 and 20 micrograms/dL). Contaminated capillary specimens were defined as those in which the capillary result exceeded the venous result by 0.12 mumol/L (2.5 micrograms/dL) or more (n = 49).

MAIN OUTCOME MEASURES

Test sensitivity and false-positive rate (equal to 1-specificity) as a function of the capillary screening cutoff value. Area under the ROC curve as a measure of screening test performance.

RESULTS

Venous blood lead levels were 0.48 mumol/L (10 micrograms/dL) or more in 20.5% and 0.97 mumol/l (20 micrograms/dL) or more in 2.3% of children. Measurement of capillary blood lead levels performed very well as a screening test with an area under the ROC curve of 0.97 at the 0.48 mumol/L (10-micrograms/dL) threshold and 0.99 at the 0.97-mumol/L (20-micrograms/dL) threshold. For a capillary cutoff value of 0.39 mumol/L (8 micrograms/dL) and an elevated blood lead level threshold of 0.48 mumol/L (10 micrograms/dL), test sensitivity is 100% and the false-positive rate is 23%. Test sensitivity drops to 91%, 63%, and 45% at capillary cutoff values of 0.48, 0.58, and 0.68 mumol/L (10, 12, and 14 micrograms/dL), respectively. The false-positive rate drops to 8%, 2%, and 1% at capillary cutoff values of 0.48, 0.58, and 0.68 mumol/L (10, 12, and 14 micrograms/dL), respectively. Changing the contamination rate by appending or deleting contaminated capillary specimens from the data set had little effect on the area under the ROC curve at either threshold.

CONCLUSIONS

In this sample of children, capillary blood lead measurement performed well as a screening test for elevated venous blood lead levels. Altering the capillary specimen contamination rate has little effect on the rest characteristics because much of the misclassification error resulted from random analytic error in the analysis of blood lead levels, which is high compared with the threshold of concern (0.48 mumol/L [10 micrograms/dL]). Because of lack of data on clinical outcomes for children with elevated blood lead levels in the 0.48- to 0.92-mumol/L (10- to 19-micrograms/dL) range, we suggest that the greatest utility be placed on avoiding false-positive misclassification. A clinical capillary screening cutoff value of 0.72 mumol/L (15 micrograms/dL) would avoid most false-positive results and would permit 100% sensitivity in detecting children with blood lead levels of 0.97 mumol/L (20 micrograms/dL) or higher.

Iron deficiency in Massachusetts communities: Socioeconomic and demographic risk factors among children

OBJECTIVES

This study examined the association between community rates of iron deficiency in children and sociodemographic characteristics of Massachusetts communities.

METHODS

Between April 1990 and March 1991, 238 273 Mssachusetts children 6 through 59 months of age were screened; iron deficiency was defined as an erythrocyte protopophyrin concentration of 0.62 micromol/L or higher and a blood lead level of less than 1.2 micromol/L. Sociodemographic data were obtained from the 1990 US Census.

RESULTS

Five percent of communities had iron deficiency rates greater than 13.9 per 100 children screened. Iron deficiency rate was positively associated with proportion of Southeast Asians (odds ratio [OR] = 1.10, 95% confidence interval [CI] = 1.08, 1.12), proportion of Hispanics (OR = 1.008, 95% CI = 1.002, 1.013), and high school incompletion (OR = 1.028, 95% CI = 1.020, 1.035). Similarly, an examination of three Massachusetts cities indicated that the iron deficiency rate was higher for children with Southeast Asian (relative risk [RR] = 3.6, 95% CI = 3.3, 3.8) and Hispanic (RR = 1.6, 95% CI = 1.5, 1.8) surnames than for all other children.

CONCLUSIONS

Wide variation exists in iron deficiency rates for children in Massachusetts communities. Community iron deficiency was associated with low socioeconomic status and high proportions of Southeast Asians and Hispanics.

Utility of a risk assessment questionnaire in identifying children with lead exposure

OBJECTIVE

To evaluate the utility of the Centers for Disease Control and Prevention (CDC) Risk Questionnaire and a behavioral risk factor questionnaire in identifying children with blood lead concentrations of 0.48 mumol/L (10 micrograms/dL) or more.

DESIGN

Cross-sectional study of 463 urban Massachusetts children (6 to 72 months of age) screened for lead with venous blood.

RESULTS

Twenty-two percent of the children had elevated blood lead concentrations. Of the five CDC questions, only one was significantly associated with an increased adjusted odds ratio for elevated blood lead: having a sibling, housemate, or playmate who was followed up or treated for lead poisoning (odds ratio, 2.7; 95% confidence interval, 1.7 to 4.2; P < .001). Children who had at least one positive or equivocal response to any of the five CDC questions (n = 318 [68.7%]) were not at higher risk than were children who displayed a negative response to all five questions (odds ratio, 1.1; 95% confidence interval, 0.7 to 1.8; P = .69). Of nine behaviors surveyed, two were associated with an increased adjusted odds for elevated blood lead: use of a pacifier (odds ratio, 2.4; 95% confidence interval, 1.3 to 4.4; P = .01) and playing near the outside of the home (odds ratio, 3.4; 95% confidence interval, 2.0 to 5.8; P < .001).

CONCLUSIONS

In this population of children, the CDC risk questionnaire did not identify a group at higher risk for lead exposure. We suggest that practitioners in urban communities screen all children according to the same schedule. We conclude that risk factors differ by community and no risk questionnaire developed at the national level should be applied across communities to target screening.

Mutation of proline-1003 to glycine in the epidermal growth factor (EGF) receptor enhances responsiveness to EGF

We have shown previously that the epidermal growth factor (EGF) receptor is phosphorylated at Ser-1002 and that this phosphorylation is associated with desensitization of the EGF receptor. Ser-1002 is followed immediately by Pro-1003, a residue that may promote the adoption of a specific conformation at this site or severe as a recognition element for the interaction of the EGF receptor with other proteins. To examine these possibilities, we have mutated Pro-1003 of the EGF receptor to a Gly residue and have analyzed the effect of this mutation on EGF-stimulated signaling. Cells expressing the P1003G EGF receptors exhibited higher EGF-stimulated autophosphorylation and synthetic peptide phosphorylation compared to cells expressing wild-type EGF receptors. In addition, the ability of EGF to stimulate PI 3-kinase activity and mitogen-activated protein kinase activity was enhanced in cells expressing the P1003G EGF receptor. Cells expressing P1003G receptors also demonstrated an increased ability to form colonies in soft agar in response to EGF. These results indicate that mutation of Pro-1003 leads to a potentiation of the biological effects of EGF. The findings are consistent with the hypothesis that Pro-1003 plays a role in a form of regulation that normally suppresses EGF receptor function.