82 ABSTRACTS

dorsal and median raphe nuclei. Depletion of cholinergic input to cortical structures was less consistent; the olfactory bulb and other cortical regions appeared to have only a slight decrease in cholinergic markers as visualized by cholinesterase histochemis- try. Intrinsic dopaminergic cells of the olfactory bulb continued to express their transmitter phenotype. These results show that viral invasion through the olfactory system appears to produce a reduction in neurotransmitter expression but not necessarily a total shut down of transmitter production in many specific cell groups. The reduction of markers for serotonin and noradrenaline is consistent with reductions of these markers in Alzheimer's dis- ease. However, the lack of significant cholinergic reduction in cortical structures following viral invasion does not correlate with the significant depletion in the disease. This work was supported by the American Health Assistance Foundation, NIH NS 23348 and NIAID AI-23482. References: 1. Bondareff, W.; Mountjoy, C. Q.; Roth, M. Loss of neurons of origin of the adrenergic projection to cerebral cortex (nucleus locus coeruleus) in senile dementia. Neurology 32:164-168; 1982.2. Doty, R. L.; Reyes, P. F.; Gregor, T. Presence of both odor identification and detection deficits in Alzheimer's disease. Brain Res. Bull. 18: 597-600; 1987. 3. Ishii, T. Distribution of Alzheimer's neu- rofibrillary changes in the brain stem and hypothalamus of senile dementia. Acta. Neuropathol. (Bed.)6:181-187; 1966.4. McLean, J. H.; Shipley, M. T.; Bernstein, D. I. Golgi-like, transneuronal retrograde labelling with CNS injections of Herpes simplex virus type 1. Brain Res. Bull. 22:867-881; 1989.5. Pearson, R. C. A.; Esiri, M. M.; Hiorns, R. W.; Wilcock, G. K.; Powell, T. P. S. Anatomical correlates of the distribution of the pathological changes in the neocortex in Alzheimer's disease. Proc. Natl. Acad. Sci. USA 82:4531-4534; 1985.6. Saper, C. L.; German, D. C.; White, C. L., III. Neuronal pathology in the nucleus basalis and associated cell groups in senile dementia of the Alzheimer's type: A possible role in cell loss. Neurology 35:1089-1095; 1985. 7. Shipley, M. T. Transport of molecules from the nose to brain: Transneuronal anterograde and retrograde labeling in the rat olfactory system by wheat germ agglutinin-horseradish peroxidase applied to the nasal epithelium. Brain Res. Bull. 15:129-142; 1985.8. Whitehouse, P. J.; Price, D. L.; Clark, A. W.; Coyle, J. T.; Delong, M. R. Alzheimer's disease: evidence for selective loss of cholinergic neurons in the nucleus basalis. Ann. Neurol. 10:122-126; 1981.

PET PROVIDES A NEW IMAGE OF ALZHEIMER'S DIS- EASE. Michael E. Phelps. Division of Nuclear Medicine and Biophysics, Department of Radiological Services, UCLA School of Medicine, Los Angeles, CA.

The imaging technologies of CT and MRI have improved the differential diagnosis of Alzheimer's, but this has been by exclu- sionary approaches. For example, CT and MRI are reasonably accurate in identifying such confounding causes as multi-infarct dementia (MID), normal pressure hydrocephalus, progressive supranuclear palsy, but provide little direct evidence in specifi- cally identifying the presence of Alzheimer's disease or mixed Alzheimer's and MID from the major confounding issues of chronic depression of the aged or "normal" aging. Information provided by CT and MRI also tends to be biased toward late stage disease, while early specific diagnosis is more beneficial. This occurs because CT and MRI identify gross structure changes associated with disease that tend to occur at late stages and are often nonspecific. PET provides a way to search for and image alterations in biochemical and biological processes that occur early in disease and provide specificity for delineating their etiology. PET studies of cerebral glucose metabolism have demonstrated a

characteristic anatomical pattern of metabolic deficiencies in mild Alzheimer's in the superior-posterior parietal cortex, with spread- ing involvement throughout parietal cortex, superior and inferior temporal cortex inferior frontal cortex and eventually into subcor- tical structures with progression of disease. These results correlate well with the known neuropathologicai distribution of the disease. Asymmetric metabolic deficits have also correlated well with the dominate neuropsychological deficits (i.e., left-sided metabolic deficits with predominate language deficits and right-sided meta- bolic deficits with predominate visuoconstructive deficits). Pa- tients with chronic depression (pseudodementia) have either normal patterns of metabolism or in some cases, metabolic deficits in the inferior frontal cortex. Normal aging has been found to produce none or a small (i.e., 10%) generalized reduction in metabolism or a localized reduction in the superior frontal cortex. PET studies of glucose metabolism and dopamine synthesis in nondemented Parkinson's patients show normal glucose metabolism and pro- found dopamine deficiencies in the caudate and lenticular nuclei. Of the Parkinson's patients who subsequently develop an Alz- heimer's syndrome, PET reveals the characteristic "Alzheimer's pattern" of metabolism concomitant with the signs and symptoms of dementia. MID patients are recognizable in PET by a rather random, yet discrete distribution of infarcts and ischemia. Com- pared to CT and MRI, PET identifies about 3 times as many areas of involvement and provides a more comprehensive picture of the functional impact of these lesions on the brain. Demented Hun- tington's patients are characterized by localized metabolic defi- ciencies in the caudate and putamen, as well as retained normal dopamine synthesis in these structures. PET provides new oppor- tunities for early and specific differential diagnosis of the demen- tias. It provides a means to assess the chemical changes in the brain of the living patient during evolution of the disease or in response to therapeutic interventions. Recent advances in spatial resolution and bioassay methods continue to expand the quality and diversity of measurements and examinations that can be performed.

BIOLOGICAL MARKERS FOR DETECTION OF BRAIN AB- NORMALITIES IN INDIVIDUALS WITH ALZHEIMER'S DIS- EASE AND IN AGED NONHUMAN PRIMATES. Donald L. Price and Edward H. Koo. Neuropathology Laboratory, The Johns Hopkins University School of Medicine, Baltimore, MD.

Alzheimer's disease (AD), characterized by progressive impair- ments in memory, language, visuospatial perceptions, and behav- ior, is the most common cause of dementia in late life. A diagnosis of definite AD requires the demonstration of senile plaques and neurofibriUary tangles (NFr) in brain. The disease preferentially affects specific brain regions and certain populations of nerve cells (defined, in part, by their locations, circuitries, and transmitter specificities) in brainstem, basal forebrain, amygdala, hippocam- pus, and neocortex. These neurons show NFT and participate in the formation of neurites, i.e., abnormally enlarged distal axons, dendrites, and nerve terminals. Within vulnerable cells, cytoskel- etal elements are altered, abnormal constituents appear, and changes occur in certain RNA and protein markers. A hallmark of AD is the presence of senile plaques, i.e., neurites surrounding extracellular amyloid fibrils. Amyloid is comprised, in major part, of a 4-kilodalton [3-amyloid protein (BAP) derived from a larger precursor (APP). The gene coding for APP, localized to chromo- some 21, is transcribed in neurons; three transcripts (two with and one without protease inhibitor domains) are present in brain. Mechanisms whereby APP is cleaved to form BAP are not yet clear. The biological basis for abnormalities in behavior and brain

ABSTRACTS 83

structure/chemistry can be clarified by investigations of animal models. Older macaques develop a variety of cognitive/memory impairments as well as abnormalities in the structure, chemistry, and function of certain neuronal populations. Moreover, these animals show some of the cellular abnormalities, i.e., formation of neurites and NFT as well as deposition of amyloid, that occur in AD. Thus, investigations of aged nonhuman primates can substan- tiaUy enhance our understanding of behavioral, neuropathological, and neurochemical abnormalities that occur in older humans and in individuals with AD. Finally, this model may be useful for testing innovative therapies, including the efficacy of growth factors and neural grafts.

ALUMINUM, ENVIRONMENT AND ALZHEIMER'S DIS- EASE: ACTIVE ROLE OR PASSIVE BYSTANDER? Daniel P. Perl and Paul F. Good. Mount Sinai School of Medicine, New York, NY.

The neurofibrillary tangle, first described by Alzheimer in 1907, along with the senile plaque, represent the two principle neuropathologic lesions identified in the brains of patients with Alzheimer's disease. Aluminum salts inoculated into the central nervous system of certain experimental animals induces neurofil- amentous lesions which are similar, but not identical, to the neurofibrillary tangles seen in Alzheimer's disease. Although some reports provide evidence of increased amounts of aluminum in the brains of Alzheimer's disease victims, such bulk elemental analysis studies have been difficult to replicate. Over the past several years we have approached this problem using several microprobe techniques in order to determine the distribution of trace elements within individual nerve cells. Using scanning electron microscopy with x-ray spectrometry, we identified accu- mulations of aluminum in the neurofibrillary tangle-bearing neu- rons of cases of Alzheimer's disease. Similar accumulations were found in the brains of the indigenous natives of Guam who suffer from parkinsonism with dementia and from amyotrophic lateral sclerosis. Recent studies using laser microprobe mass analysis clearly demonstrate that the accumulation of aluminum identified within the perikaryon of neurofibrillary tangle-bearing neurons is located within the neurofibrillary tangle itself. The concentrations of aluminum within the affected neurons are several fold greater than that of the surrounding neuropil or adjacent unaffected cells. Although this ongoing research still cannot ascribe a causal role for aluminum in the etiology and/or pathogenesis of the neu- rofibrillary tangle; the data suggest that environmental factors related to trace elemental constituents may play an important role in the formation of this type of cellular pathology. The importance of the recently reported advances related to genetic influences in Alzheimer's disease cannot be denied, yet it remains highly likely that this disorder, as with the other common chronic diseases of the elderly, represents an interplay of both genetic and environ- mental factors. Considering the repeatedly positive trace element microprobe data and the strong epidemiologic evidence related to similar neurodegenerative diseases encountered among the natives of Guam, aluminum remains a likely candidate for involvement in the underlying environmental factors of importance in Alzheimer's disease. (Supported in part by grant AG-01415 of the National Institutes of Health.)

IMMUNOLOCALIZATION OF THE 13-AMYLOID PRECUR- SOR PROTEIN IN BRAIN TISSUE. G. Perry, S. Siedlak, P. Mulvihill, M. Kawal, M. Mijares, P. Gambetti, D. Lowery, S. Sharma, L. Maggiora, J. Cornet and B. Greenberg. Institute of Pathology, Case Western Reserve University, Cleveland, OH and

Upjohn Company, Kalamazoo, MI.

Senile plaques (SP) and neurofibrillary tangles are the patho- logical characteristics of Alzheimer disease (AD). Proteolysis of a larger precursor protein leads to the formation of the 42-amino acid residue amyloid fragment (13-protein), which is a major component of the core of SP. cDNAs for the amyloid precursor protein (APP) have been isolated, and sequences of 695, 751 or 770 amino acids, differing by a serine protease inhibitor insert, have been reported. However, the cellular origin and the site of proteolysis of APP in Alzheimer disease remain to be established. In an immunocytochemical study of brain tissue from cases of AD, we produced polyclonal antisera in rabbits to synthetic peptides of 11 to 42 amino acid residues long, corresponding to twelve regions of APP and spanning residues 18 to 678 (including [3-protein) of the insertless form. Antisera were raised to keyhole limpet haemocyanin or a-thyroglobin conjugates of the peptides or, for sequences in 13-protein, to the peptide alone. The antisera specif- ically recognized the peptide used as immunogen in ELISA or immunodot assays. Most of the antisera recognized APP produced by in vitro translation of a full length APP cDNA clone. Antibod- ies raised to sequences containing all or part of 13-protein-stained SP cores, irregular areas that appeared to be plaques, and some vessels. But antibodies raised to other APP sequences recognized only a subset of this pattern, staining the periphery or irregular areas surrounding the SP cores and similar areas displaying no core. The staining of the periphery of SP cores was better appreciated with Congo red (a marker for amyloid) under polar- ized light. Occasional cell processes within the SP were also intensely immunostained. Immunopurified N-terminal (residues 45 to 62) and C-terminal (residues 638 to 658) antisera recognized the same structures as the original antisera, although with less background staining. Specificity of the immunoreaction with these two antisera was further shown by blockage of senile plaque staining by adsorption with the peptide used as immunogen. Although not all antibodies were effective in immunostaining, the absence of any difference in staining pattern with antibodies to APP is probably present in senile plaques. Our results indicate that: 1) antibodies to APP sequences outside those contained within [3-protein do not recognize congophilic amyloid deposits; 2) APP deposition precedes the formation of [3-amyloid; and 3) proteolysis of APP to [3-amyloid occurs within the senile plaque. We speculate that the abnormality leading to the senile plaque is APP accumulation, which possibly defines the plaque, rather than altered APP metabolism alone. Efforts are underway to clarify the site of APP entry and accumulation (vascular, neuronal, or endothelial) and processing, important in defining SP pathogenesis in AD. (Supported by the American Health Assistance Founda- tion.)

ASSESSMENT OF FUNCTIONAL COMPETENCE IN ALZ- HEIMER'S DISEASE. Francis J. Pirozzolo, Roderick K. Mahu- fin, Barbara H. Debettignies. Department of Neurology, Baylor College of Medicine, One Baylor Plaza, Houston, TX.

Once a diagnosis of Alzheimer's disease (AD) is established, questions must be addressed by both practitioner and caregiver regarding functional status of the patient. These include decisions about self-care, safety, necessity for home assistance, and possible placement in a long-term care facility. At present, however, there is little information on which to quantify or project the rate of functional decline of a patient with AD. The present project was designed to develop a standardized, objective behavioral assess- ment battery that measures everyday functional skills of the AD