Abstracts from current literature

Abstract

s from Current Literature Stains for the differential diagnosis of degenerative dethe cortex. They are tharacteristically negative for tau and mentias. David G Munoz, Departments of Pathology and synuclein, but express intense ubiquitin immunoreactivity. Clinical Neurological Sciences, University of Western OnThe differentiation of these and other neurodegenerative tario, London, Ontario, Canada, N6A, 5CI disorders is important in our understanding of the pathoWith our ever-increasing age, dementia is becoming a physiology of these diseases. By applying this handful of major health problem. Neurodegenerative &mentias constihighly useful immunohistochemical and histochemical tute the vast majority of cases, with Alzheimer's disease stains, the often confusing and overlapping diseases can be representing 70-80% and dementia, with Lewy bodies and sorted out with precision. This article would make a highly low bar atrophies accounting for most of the remaining useful desk reference for any histotechnologist involved in cases. Histotechnological advances have aided greatly in the neuro~atholog~. differential diagnosis of these diseases, which is now inBiotechrzic Histochern 74(6):3 1 1-320, 1999 creas ingl~ with the and institution lntracellular fragmentation of bone resorption products of specific medications for these disorders. Dr. Munoz reby reactive oxygen species generated by osteoclastic tarviews the application of the special Gallyas silver stain and trate-resistant acid phosphatase. JM Halleen, s Raisanen, several antibodies for immunohistochemical demonstration JJ Sales, et al, Department of Anatomy, University of of specific proteins to differentiate among the various forms Turku, Kiinamyllynkatu 10,20520 ~ ~ ~ k ~ , ~ i ~ l ~ ~ d of neurodegenerative diseases. The Gallyas silver stain is an ~h~ increasing prevalence of osteoporosis and its ultiessential element in differentiating these disorders, and its mate consequences of fracture risk in the elderly is driving historical development principle and specific staining Proincreased research effort into bone cell biology and osteot0c01 are presented for the reader to use as a bench referporosis treatment. A prime target for osteoporosis treatment enCe. It is exquisitely selective for Alzheimer's disease beis the osteoclast because it is the only known cell to mediate Cause this silver stain selectively stains pathologic tau bone resorption, However, the growth, differentiation, and proteins os (p-tau); it stains the characteristic neurofibrillary function of mature osteoclasts are complex and incomtangles, neuropil threads, and neurites in plaques. This alpletely understood processes. In this brief communication, lows low power observation and recognition of the characHalleen et a1 concisely demonstrate, through a series of teristic widespread lesions in Alzheimer's disease. experiments including laser scanning confocal miroscopy, In conjunction with the Gallyas stain, immunohistochemhow tartrate-resistant acid phosphatase (TRAP) may conical staining of a select set of proteins, including tau, neutribute to bone matrix resorption intracellularly. Firstly, rerofilament, ubiquitin, a-synuclein, and aB-crystallin, when combinant rat bone TRAP was shown to be uniquely able to used judiciously and in the right combinations, can clearly generate destructive reactive oxygen species (ROS) in the distinguish among the other neurodegenerative diseases. presence of hydrogen peroxide by virtue of the enzyme's For example, the Lewy bodies in the deep cortical regions iron content in vitro and in situ. This fentin reaction was not are p-tau negative, but the inclusions can be easily demonfacilitated by 2 other zinc-containing osteoclast products, strated with im~nunohistochemical staining for ubiquitin carbonic and hydrase I1 (or matrix metalloproteinase), both and a-synuclein. In classical Pick's disease, nuclear incluof which play roles in extracellular matrix resorption. Secsions are characteristically negative for the Gallyas stain, ondly, using LSC microscopy of cultured, resorbing osteoyet positive for other silver stains, and may show variable clasts; TRAP (labeled red) and biotinylated bone matrix staining for tau proteins, depending upon the antibodies (labeled green) were shown to co-localize within vesicles used. Ubiquitin reactivity in Pick bodies is typically very inside the osteoclasts, whereas TRAP was not localized to low and barely above background. In corticobasal degenthe resorption lucanae outside the cell. Finally, gel filtration eration, the neuronal inclusions express p-tau, but not ubiqchromatography of mixtures of TRAP Type I collagen and uitin. In addition, the inclusions take a variety of shapes hydrogen peroxide revealed specific fragmentation of the unlike Pick bodies (which are uniformly round), and all of collagen in the presence of hydrogen peroxide whereas the shapes of inclusions are stained intensely by the Gallyas TRAP itself was unaffected. silver technique. In dementia with inclusions, tau, and The authors conclude that intracellular fragmentation synuclein negative, expressing ubiquitin reactivity (ITSNU) of bone matrix occurs as part of the total resorption procharacteristic inclusions are located in a granular cell layer cess and is mediated by TRAP in a novel mechanism of of the dendate gyrus, the cingulate gyrus, and elsewhere in oxidative destruction by hydroxyl radicals and superThe Journal of Histotechnology I Vol. 23, No. 4 / December 2000 359 oxide anion facilitated by redox active iron in the TRAP molecule. J Biol Chenz 274 (33):22907-22910, 1999 Contribution of molecular genetic data to the classification of sarcomas. Marc Ladanyi and Julia A Bridge, Department of Pathology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY Certain sarcomas can now be classified according to recurrent chromosomal translocations that lead to abnormal expression of hybrid or fusion gene products; often transcription factors. Overexpression of mutant transcription factors are believed to be important in the pathogenesis of tumors and, in some instances, to be initiating events in neoplastic transformation. Ladanyi and Bridge begin their concise review by presenting a list of well-defined translocations associated with some sarcomas, including, among others, Ewing's sarcoma, liposarcoma, rhabdomyosarcoma, chondrosarcoma, synovial sarcoma, and fibrosarcoma. A disc~rssion of the various methods to detect translocations follows: Reverse-transcriptase-polymerase chain reaction (RTPCR) has greatest sensitivity and specificity when applied with good experimental controls. When mutations have occurred in some tumors preventing PCR primer annealing to target sequences, Southern blotting is a reliable back-up method, but req~~ires much tissue for extraction of DNA. @ Fluorescence in situ hybridization (FISH) is sensitive and provides individual cell localization of translocations within heterogeneous tissues and can be applied to interphase cells on smears. @ Chromosome "painting" methods permit visualization of entire translocated chromosomal segments in metaphase cells. The authors recommend that pathology laboratories involved in molecular diagnostics develop capabilities to perform a spectrum of methods to confirln or resolve discrepant results. With some chromosomal markers, archival paraffin embedded tissues are suitable for molecular diagnostics, provided careful attention is paid to methods of RNA extraction. In certain circ~imstances, a fi~sion gene product may possess unique antigenic determinants and be expressed in great excess, allowing i~iim~~nohistochemical localization. This method is now limited to only a few tumor types, but advances need only additional antibody development. The authors summarize several instances in which recent reclassification of some disease entities is based on common chromosomal translocations. Finally, they offer explanations on sources of error that can cause discrepant results. The authors conclude that overall, correlation between histopathological classification and genetic classification remains high. Their study strengthens rather than revolutionizes certain nostalgic concepts of tumor relatedness. Huin Pat1701 3 1 532-538, 2000 Innovative Technology Laser capture microdissection: sensitive immunoassay of tissue cell proteins procured by laser capture microdissection. NL Simone, AT Remaley, L Charboneau, et al, NCI and Clinical Pathology Department, Clinical Center, National Institutes of Health, Bethesda, MD, and the Center for Biologic Evaluation and Research, FDA, Wash-