complex 1 activity in a dose-dependent manner (10 nM to 10 mM). Other classes of neuroleptics were also studied and were effective as follows: phenothiazines > butyrophenones > thioxanthenes > diphenylbutylpiperidines > indolics, while atypical neuroleptics such as clozapine and pimozide caused inhibition only at the highest dose (i.e., 10 mM). In reviewing the structures of these neuroleptics, it seems that those compounds that can readily be oxidized have the strongest inhibitory effects. Moreover, we have preliminary data that show that free radical scavenger compounds such as ascorbic acid, glutathione, and superoxide dismutase potently attenuated the fluphenazine-induced inhibitory effects on complex I activity (V. Jackson-Lewis and S. Przedborski, in unpublished data). Accordingly, we have concluded that the effects of neuroleptics on complex I activity are likely medi- ated by free radical production. This view is consistent with the observation that complex I is particularly sensitive to free radical attack [4]. Therefore, if mitochondrial deficits in complex 1 activity underlie the development of TD, which remains to be demonstrated, then the use of antioxidant ther- apy as cotreatment to the antipsychotic therapy may prevent or attenuate the development of TD.

Movement Disorder Group Department of Neurology Columbia Universiq New York. N Y I0032

Reference.r 1. Burkhardt C, Kelly JP, Young HL, et al. Neurolepric medications

inhibit complex I of the electron transport chain. Ann Neurol 1993;33:512-5 17

2. Jackson Lewis V, Przedborski S, Jiang H, Fahn S. Effect of neuro- leptics on the mitochondrial electron transport chain. Soc Neu- rosci Abstr 1992;18:1103 (Abstract)

3. Jacksoti-Lewis V, Naini AB, Przedborski S, et al. Catecholamines inhibit mirochondrial complex I activity in rat brain. Soc Neurosci Abstr 1991 ; 17: 1276 (Abstract)

4. Zhang Y , Marcillat 0, Giulivi C, et al. The oxidative inactivation of mitochondrial electron transport chain components and ATPase. J Biol Chem 1990;265:16330-16336

Reply Carolyn Burkhardt, MD, and W. Davis Parker, MD

We appreciate the authors calling our attention to their ab- stract [ 1 ] and noted with interest their data indicating inhibi- tory effects of neuroleptics on complex I. We find the sugges- tion that these agents are likely to generate free-oxygen radicals as a consequence of their disruption of the normal electron path to be an attractive one. We have recently found that electron transport chain inhibition in isolated rat brain mitochondria does indeed lead to OH radical production as characterized by DMPO spin-trap experiments (unpublished data). Given the intense reactivity of this radical, its presence would certainly lead to peroxidative damage to the inner mitochondrial membrane and to the attached peptide ele- ments. Suppression of its production, or quenching it after it has been produced, might well be clinically useful in de- creasing the occurrence of tardive dyskinesia or-other extra- pyramidal syndromes consequent to neuroleptic therapy. It would be of great interest to know whether patients chroni-

cally treated with neuroleptics suffer oxidative damage to brain mitochondrial DNA, as has been found in normal aging [2). Damaged mitochondrial D N A could in theory lead to an irreversible condition, as the mitochondrial D N A would no longer be able to generate normal electron-transport chain-complex subunits, which it encodes, including parts of complex I. If abnormal complex I activity is related to extra- pyramidal complications of neuroleptics, this could explain the potential irreversible nature seen in tardive dyskinesia.

Westerri Neurological Group 1601 E. 19th Avenue, Suite 4400 Denier, CO 802 18

References 1. Jackson-Lewis V, Przedborski S, Jiang H, Fahn S. Effect of neuro-

leptics on the mitochondrial electron transport chin. Soc Neu- rosci Abstr 1992;18:1103 (Abstract)

2. Mecocci P, MacGarvey U, Kaufman AE. et al. Oxidative damage to mitochondrial DNA shows marked age-dependent increases in human brain. Ann Neurol 1993;34:607-616

The Amino Acid Sequence of Neuritic Plaque Amvloid from a Familial Alzheimer’s Disease Patient Thomas Wisniewski, MD, Maciej Lalowski, MS, Efrat Levy, PhD, Maria R. F. Marques, BS, and Blas Frangione, MD, PhD

Alzheimer’s disease (AD) is characterized by the deposition of P-amyloid (AP) in the form of neuritic plaques and con- gophilic angiopathy. AP is a normal degradation product of a large precursor protein, PPP. The amino acid sequence of AP from sporadic AD cases is known to have heterogeneous amino and carboxyl termini, with vascular amyloid having 39 to 40 residues and neuritic AP having 42 to 43 residues predominately (for review, see [I]). In a minority of early onset familial AD pedigrees PPP mutations have been found. The PPP mutation associated with the Dutch variant of AD of glutamine for glutamic acid [Z), which occurs at residue 22 of AP, is known to increase the fibrillogenicity of AP El]. Three of the known pPP770 mutations occur at codon 717 where valine is replaced by isoleucine, phenylalanine, or gly- cine (for review, see {3}). This codon is only four amino acids away from the known carboxyl terminus of neuritic plaque AP. The amino acid sequence of AP from familial AD is not known.

We have extracted neuritic plaque amyloid from an early- onset familial A D patient, kindly provided by D r G. G. Glen- ner from the National Alzheimer’s Disease Brain Bank. The patient died at age 61, with an onset of symptoms at age 46. The mother, sister, and two brothers were known to have died of AD; autopsies were performed on the siblings. The usual age of onset in the family was 47 with death occurring at approximately 53 years of age.

Exons 16, 17, and 18 of PPP,,,, were sequenced with stan- dard procedures [2] and were found to be normal. The neu-

Annals of Neurology Vol 35 N o 2 February 1994 245

ritic plaque were extracted by established protocol [4]. The amyloid enriched fraction was run on a tricine gel and trans- ferred to a PVDF membrane (Immobilon, Millipore Corp). The AP protein band was excised, reduced with dithiothrei- tol, and subject to cyanogen bromide cleavage, which is pre- dicted to cleave the methionine at position 35 of AP. N- terminal sequence analysis was performed on a 477A sequencer (Applied Biosystems, Foster City). The follow- ing sequences were obtained: VGGVVIA(m) and DAEFR- HDSGYEVHIIQKLVFFAEDVGSNKGA, corresponding to Ap36-42(43, 44) and Apl-30. In addition, a minor se- quence began with alanine at residue 2 of AP. The yield for threonine and valine at AP residues 43 and 44 was very low, indicating that the majority of AP ended at position 42. This finding indicates that neuritic plaque arnyloid from this famil- ial A D case has the same major sequence as that of sporadic AD, although the carboxyl terminus is slightly more hetero- geneous and elongated. This is in agreement with a paper stating that plaque amyloid from two families with different PPP7,” mutations at codon 717 is predominantly 42 amino acids long (51. Therefore, these mutations do not influence the amino acid sequence of AP. These cases suggest that in familial A D patients both with known PPP mutations and without, the major cleavage sites on PPP that produce AP are the same as in sporadic cases.

Departments of Pathology and Neurology New York University Medzcal Center N e u York, NY 10016

This research is supported by NIH grants KO8AG00542-01, AG08721, and AG10953 (LEAD), and Grant IIRG-91-102 from the Alzheimer’s Disease and Related Disorders Association.

Ref rences 1. Wisniewski T, Frangione B. Molecular biology of Alzheimer amy-

loid-Dutch variant. Mol Neurobiol 1992;1:?5-86 2. Levy E, Carman MD, Fernandez-Madrid IJ, et al. Mutation of

the Alzheimer’s disease arnyloid gene in hereditary cerebral hem- orrhage-Dutch type. Science 1990;248: 1124-1 126

3 . Hardy J. Framing P-amyloid. Nature 1992;1:233-234 4. Gorevic PD, Goni F, Pons-Estel B, et al. lsolation and partial

characterization of neurohbrillary tangles and amyloid plaque core in hlzheimer’s disease: immunohistological studies. J Neuro- pathol Exp Neurol 1986;45:647-664

5 . Liepniek JJ, Ghetti B, Farlow M, et al. Characterization of amy- loid fibril P-peptide in familial Alzheimer’s disease with APP777 mutations. Biochem Biophys Res Commun 1994 (in press)

Multifocal Motor Newopathy Roland N. Auer, MD, PhD, FRCPC

In their article (Pathological findings at the site of conduction block in multifocal motor neuropathy. Ann Neurol 1993;33: 152-158), Kaji and colleagues describe the neuropathology of peripheral nerve in two cases of multifocal motor neuropa- thy. Axons with thin myelin sheaths are described, and onion bulbs. The case is similar to our previously published case

(Can J Neurol Sci 1989;16:194- 197). However, the authors, on page 157 of their discussion, state that “Auer and col- leagues also reported the pathological findings in a patient with pure motor clinical manifestations. They reported no electrophysiological confirmation of conduction block before biopsy.” O n page 195, we clearly state that conduction block was seen. This was before the biopsy was taken.

Kaji and colleagues further go on to state that “the histo- logical findings consisted of chronic demyelination and onion bulb formation without inflammatory changes. They de- scribed neither bare axons nor very thin myelin sheaths asso- ciated with large axons. . . .” W e clearly state on page 195 in the legend to Figures 2 and 3 that very thin myelin sheaths were seen associated with large axons and, in fact, illustrate in Figure -3 the contrast between normally thick myelin sheaths surrounding large axons and thinner myelin sheaths.

We wish to direct your attention to the misquoting of our article in view of the resultant apparent dissimilarity with our case, when actually the cases are more similar than Kaji and colleagues state in their discussion, due to the above errors in quotation from our 1989 article.

Department of Pathology University of Calgaty Health Sciences Center Culgaty, Alberta, C a n a h T2N 4N1

Reply Ryuji Kaji, MD, PhD, and Jun Kimura, MD

W e appreciated D r Auer’s concern regarding the quotation of his report 11) in our recent article 121, because it high- lighted the critical difference between the patients in the two articles. The most intriguing aspect of multifocal motor neuropathy relates to the persistence, but not the presence, of conduction block (31. Our report was intended to shed light upon the pathophysiology of this unusual electrophysio- logical feature, rather than ordinary demyelination per se as the pathological substrate of conduction block 141.

The early report of this condition with some sensory involvement has already shown that some demyelinative changes exist in the nerve biopsied [ 3 ] , as confirmed by Dr Auer in his patient. Because conduction can be restored by remyelination with a layer of myelin thinner than normal [ S } , findings of axons surrounded by thin myelins that are ordinarily encountered in other dernyelinative neuropathies fail to explain the persistence of conduction block. In this context, we felt it was crucial to physiologically localize the exact site of abnormality before biopsy. Perusing Dr Auer’s case, we were uncertain whether “a marked degree of con- duction block proximally” coincided with the specimen taken at biopsy. We were also unable to evaluate in his case the persistent conduction block in the absence of the actual illus- tration of the waveforms clearly delineating the location of the physiological abnormality.

We tried to emphasize, perhaps less convincingly than we hoped, the pathological features of impaired remyelination as the basis of persistent conduction block, by quantitating the ratios of myelin thickness to axonal caliber, and by docu- menting the unusually large bare axons not surrounded by Schwann cells.

246 Annals of Neurology Vol 35 No 2 February 1994