Donald L. McEachron

Advances in image processing for autoradiography

The next generation of techniques for image processing in autoradiography will extend the range for what is already a broad band method for functional mapping. Among the new tools under development are techniques to correct for tritium quenching. With these, high resolution, accurate 2-deoxyglucose mapping will be feasible. Also being developed are automatic segmentation algorithms which will permit rapid surveys of a large number of structures in a large number of brains. Together with recent refinements in other aspects of image processing of autoradiograms, these tools will provide both better quantification accuracy and faster analysis speed.

Regular ArticleThree-Dimensional Reconstruction of Activated Columns from 2-[14C]Deoxy-d-glucose Data

Three-dimensional (3-D) reconstruction of autoradiograms can provide new insights into the functional relationship of neural regions. To reach full potential, however, 3-D reconstruction must be both accurate and efficient. In this paper, we present a novel image matching algorithm that simultaneously aligns a set of serial sections and uses the method to reconstruct whisker barrels from the rat cerebral cortex. We initially compared several alignment techniques and found that our Multi-Set Registration (MSR) algorithm produced superior accuracy. This algorithm is based on a least-squares minimization technique and is able to simultaneously register a set of serial sections with subpixel precision (30-micron accuracy). We applied our new technique to the 3-D reconstruction of a series of autoradiograms. Our objective was to visualize and measure the 3-D metabolic (functional) shape of normal (control) and developmentally altered (plastic) C3 vibrissa columns in the first somatosensory area of the rat cerebral cortex. The plastic C3 metabolic column showed a nearly 450% increase in volume when compared to the control column. In addition, the lesion-altered C3 column-in contrast to the normal C3 column-displayed no central zone of high activity, and patches of higher metabolic activity were scattered throughout the columnar profile. This metabolic activity was not confined to the cylindrical column, but extended tangentially as radiating fingerlike projections toward neighboring barrels.

The variation in user drawn outlines on digital images: effects on quantitative autoradiography.

Variation in user outlines drawn to delineate neural regions is the only source of error added to autoradiographic images after the images have been digitized. By analyzing data compiled from many outlines drawn by several different investigators, it was demonstrated that this variation constitutes a major source of error affecting quantitative autoradiography. Both the gray level variation and average within a region, as well as the specific pixels included in an outline, were affected. However, using the intersection of multiple outlining attempts surrounding any given region and a consistent set of outlining criteria, it was possible to delineate a region which remained consistent from user to user. A technique for automating the consistent outlining process is discussed.

The analytic and functional accuracy of a video densitometry system

Applications using radiotracers and quantitative film autoradiography are increasing dramatically in the neurosciences. Microcomputer-based image analyzing systems with video input have been developed to provide rapid quantification of autoradiographic images on relatively inexpensive systems. However, there has been some question as to whether such systems can reliably produce high levels of densitometric accuracy, especially when compared to mechanical scanners which are standard in research requiring extreme fidelity of measurement. We report methods and results from tests done to determine the analytical and functional accuracy of the Drexel Unix-based Microcomputer image Analysis System (DUMAS), which is a video densitometric system designed to provide quantitative data from autoradiograms. Analytical accuracy was determined by measuring photometric uniformity, the optical density transfer function, temporal stability, geometric uniformity, and flare. In addition, data are provided on the resolution of the system at several magnifications. Functional accuracy, the accuracy of the estimates of mean isotope concentrations in diverse neural structures, was determined by comparing the results obtained on the DUMAS system with the results from analyzing the same [14C]2-deoxyglucose images with two different Optronics P1000 systems. Our results show that, provided care is taken in the choice of a camera and a light source, the analytic accuracy of videodensitometry is high. Its functional accuracy is also high in that measurements of radioisotope concentrations in diverse neural structures made on the DUMAS system agree closely with the measurements from a properly adjusted Optronics P1000 system. The rapidity and economy of videodensitometry is not, therefore, obtained at the sacrifice of densitometric accuracy. Given adequately tested hardware and provided that suitable checks on instrument calibration and adjustment are made, the errors in autoradiographic quantification due to the image analyzing system itself are minor in comparison to other sources of error, including, as we show, variations in the users delineation of the boundaries of neural structures.

Image processing for the rest of us: The potential utility of inexpensive computerized image analysis in clinical pathology and radiology

Recent progress in computer technology in both hardware and software, combined with marked cost reductions, have placed quantitatively accurate video densitometry systems within the reach of the individual clinician, biomedical researcher, and community hospital. While much of the attention generated by advances in image processing has focussed on larger scale procedures, such as CAT, chemical shift, and positron emission tomography, important applications can be found for considerably more modest systems. In this article, we discuss three such applications of DUMAS, a personal computer-based imaging system developed by the Image Processing Center at Drexel University. A potential technique for quantifying numbers of estrogen receptors in tumorous breast tissue samples as a predictor of patient responsiveness to hormonal therapy is described first, along with possible sources of error. The second application, also related to clinical pathology and cancer, outlines methods for relating changes in nuclear and cell morphology to the diagnosis of Sezary Cell Syndrome. The utility of binary image filtering methods in the classification of cell types is discussed. The third application involves the development of a semi-automatic procedure for the determination of vessel diameter in arteriograms. A detailed description of the optimization and curve-fitting algorithms is provided along with preliminary test results comparing various approaches. The need for user demand to fuel research and development in small-scale imaging systems is also discussed.

Lithium lengthens circadian period but fails to counteract behavioral helplessness in rats

We report the results of an additional study investigating whether lithium-induced lengthening of circadian period would alter escape performance in rats previously subjected to inescapable shock

Cold acclimation increases gene transcription of two calcium transport molecules, calcium transporting ATPase and parvalbumin beta, in carassius auratus lateral musculature

We studied the effects of cold acclimation on gene transcription in goldfish (Carassius auratus) lateral musculature. We incorporated the use of high-density cDNA filter array technology followed by validation of the results with real-time quantitative RT-PCR. Array analysis revealed that the message levels of two calcium transport molecules, calcium transporting ATPase and parvalbumin beta, were higher in cold acclimated fish muscle when compared to warm acclimated fish muscle. Array results indicated that the calcium transporting ATPase message was approximately 8 fold greater in cold acclimated fish muscle, and the parvalbumin beta message was approximately 6 fold greater in cold acclimated fish muscle. The results were confirmed using real-time semi-quantitative RT-PCR. The results are in accordance with known acclimatory response in the calcium transport physiology of Cyprinid muscle.

Pattern of [14C]2-deoxyglucose concentration associated with potentiation of reproductive behavior by prostaglandin E2.

One indication of receptive behavior of the female leopard frog, Rana pipiens, is absence of a release call during tactile stimulation of the trunk. Prostaglandin E2 (PGE2) inhibits this call. This experiment demonstrates a different pattern of [14C]2-deoxyglucose concentration in brains of 5 receptive females silenced by 1 microgram/g PGE, compared with that in 3 unreceptive, vocalizing controls injected with deionized water. 14C concentrations were measured in areas important for vocalization in frogs, in limbic system structures and in parts of the brain that receive somatosensory input. There was high activity relative to the rest of the brain in the receptive, silent PGE2-treated females in the caudal part of the anterior preoptic nucleus, in the dorsal habenula, and in the dorsal tegmental area of the medulla lateral to the pretrigeminal nucleus.

Chronobioengineering indoor lighting to enhance facilities for ageing and Alzheimer's disorder

Evolutionary processes generate a variety of paradoxes which must be faced in order to design the most effective structures to fulfil various human requirements and preferences. One of these paradoxes comes from the evolution of circadian rhythm systems, which are normally synchronized to the geophysical cycle of night and day and coordinate internal temporal order, but are now in conflict with modern technology and the 24/7 paradigm for urban living. Modern lighting systems have traditionally focused on providing sufficient illumination for people to navigate and manipulate their environments without regard to the side effects that lighting might have on temporal aspects of behaviour and physiology. However, studies involving shift work and other applications of artificial lighting have indicated that these side effects can be quite significant. Furthermore, when an ageing circadian system is coupled with a deteriorating physiology, the side effects of a 24/7 artificially illuminated indoor environment can be especially debilitating, especially for older adults with dementia. Chronobiology is the field of biology that examines periodic (cyclic) phenomena in living organisms, whereas photobiology is the scientific study of the interaction of light on living organisms. Chronobioengineering is an emerging field of scientific study that translates research results and concepts from these fields into practical applications. The following discussion focuses on the use of light cycles to synchronize circadian rhythms and ways human health and wellbeing can be enhanced through light-emitting diode (LED) lighting in the ageing population, specifically those with dementia of Alzheimers type. The hypothesis is that the implementation of a lighting system specifically designed to synchronize circadian rhythms in this population will alleviate symptoms of dementia and thus enhance the quality of life for both residents and caregivers. The research team is working with a lighting industry partner to manufacture a 2′ × 2′ retrofit LED luminaire for installation at St. Francis Country House, a skilled-nursing facility near Philadelphia. Research includes working with the nursing home caregivers and administrators to establish criteria and protocols for evidence-based design research that will evaluate the efficacy of the daylight-matching luminaire.

Epidemiology: Teaching the Fundamentals

T HE field of epidemiology represents an excellent choice for teaching numerous aspects of biology, mathematics and simulation in a clear and cost-effective manner. The topic is relevant to individual students with a wide range of backgrounds and educational levels, and protocols can readily be modified for the interests of the class with which one is dealing. In this paper, we show how a basic modeling approach was used with eighth-grade students participating in a special program at Drexel University, and with undergraduate business majors taking a course in biology as a breadth requirement at the same University. We also show how this simulation can be placed into the context of a more comprehensive investigation into microbiology and epidemiology. Finally, we provide suggestions for enhancing this approach to model more complex systems. Classroom details are to be found under