Towards an evidence-based process for the clinical interpretation of copy number variation.

The evidence-based review (EBR) process has been widely used to develop standards for medical decision-making and to explore complex clinical questions. This approach can be applied to genetic tests, such as chromosomal microarrays, in order to assist in the clinical interpretation of certain copy number variants (CNVs), particularly those that are rare, and guide array design for optimal clinical utility. To address these issues, the International Standards for Cytogenomic Arrays Consortium has established an EBR Work Group charged with building a framework to systematically assess the potential clinical relevance of CNVs throughout the genome. This group has developed a rating system enumerating the evidence supporting or refuting dosage sensitivity for individual genes and regions that considers the following criteria: number of causative mutations reported; patterns of inheritance; consistency of phenotype; evidence from large-scale case-control studies; mutational mechanisms; data from public genome variation databases; and expert consensus opinion. The system is designed to be dynamic in nature, with regions being reevaluated periodically to incorporate emerging evidence. The evidence collected will be displayed within a publically available database, and can be used in part to inform clinical laboratory CNV interpretations as well as to guide array design.

Role of Rho kinase isoforms in murine allergic airway responses.

Inhibition of Rho-associated coiled-coil forming kinases (ROCKs) reduces allergic airway responses in mice. The purpose of this study was to determine the roles of the two ROCK isoforms, ROCK1 and ROCK2, in these responses. Wildtype (WT) mice and heterozygous ROCK1 and ROCK2 knockout mice (ROCK1(+/-) and ROCK2(+/-), respectively) were sensitised and challenged with ovalbumin. ROCK expression and activation were assessed by western blotting. Airway responsiveness was measured by forced oscillation. Bronchoalveolar lavage was performed and the lungs were fixed for histological assessment. Compared with WT mice, ROCK1 and ROCK2 expression were 50% lower in lungs of ROCK1(+/-) and ROCK2(+/-) mice, respectively, without changes in the other isoform. In WT lungs, ROCK activation increased after ovalbumin challenge and was sustained for several hours. This activation was reduced in ROCK1(+/-) and ROCK2(+/-) lungs. Airway responsiveness was comparable in WT, ROCK1(+/-), and ROCK2(+/-) mice challenged with PBS. Ovalbumin challenge caused airway hyperresponsiveness in WT, but not ROCK1(+/-) or ROCK2(+/-) mice. Lavage eosinophils and goblet cell hyperplasia were significantly reduced in ovalbumin-challenged ROCK1(+/-) and ROCK2(+/-) versus WT mice. Ovalbumin-induced changes in lavage interleukin-13, interleukin-5 and lymphocytes were also reduced in ROCK1(+/-) mice. In conclusion, both ROCK1 and ROCK2 are important in regulating allergic airway responses.

Pharmacologic control of homeostatic and antigen-driven proliferation to target HIV-1 persistence.

The presence of latent human immunodeficiency virus 1 (HIV-1) in quiescent memory CD4 + T cells represents a major barrier to viral eradication. Proliferation of memory CD4 + T cells is the primary mechanism that leads to persistence of the latent reservoir, despite effective antiretroviral therapy (ART). Memory CD4 + T cells are long-lived and can proliferate through two mechanisms: homeostatic proliferation via γc-cytokine stimulation or antigen-driven proliferation. Therefore, therapeutic modalities that perturb homeostatic and antigen-driven proliferation, combined with ART, represent promising strategies to reduce the latent reservoir. In this study, we investigated a library of FDA-approved oncology drugs to determine their ability to inhibit homeostatic and/or antigen-driven proliferation. We confirmed potential hits by evaluating their effects on proliferation in memory CD4 + T cells from people living with HIV-1 on ART (PLWH) and interrogated downstream signaling of γc-cytokine stimulation. We found that dasatinib and ponatinib, tyrosine kinase inhibitors, and trametinib, a MEK inhibitor, reduced both homeostatic and antigen-driven proliferationby >65%, with a reduction in viability <45%, ex vivo. In memory CD4 + T cells from PLWH, only dasatinib restricted both homeostatic and antigen-driven proliferation and prevented spontaneous rebound, consistent with promoting a smaller reservoir size. We show that dasatinib restricts IL-7 induced proliferation through STAT5 phosphorylation inhibition. Our results establish that the anti-cancer agent dasatinib is an exciting candidate to be used as an anti-proliferative drug in a clinical trial, since it efficiently blocks proliferation and iswell tolerated in patients with chronic myeloid leukemia (CML).

Comparison of two automated immunohistochemical procedures for the diagnosis of scrapie in domestic sheep and chronic wasting disease in North American white-tailed deer (Odocoileus virginianus) and mule deer (Odocoileus hemionus).

Two commercially available automated immunohistochemistry platforms, Ventana NexES and DakoCytomation Autostainer Universal Staining System, were compared for diagnosing sheep scrapie and cervid chronic wasting disease. Both automated platforms used the same antiprion protein monoclonal primary antibodies, but different platform-specific linker and amplification reagents and procedures. Duplicate sections of brainstem (at the level of the obex) and lymphoid tissue (retropharyngeal lymph node or tonsil) from the same tissue block were immunostained for the comparison. Examination of 1,020 tissues from 796 sheep revealed 100% concordance of results between the Ventana NexES and DakoCytomation platforms for diagnosing sheep scrapie from lymphoid tissue (103/103 positive; 405/405 negative) and brainstem (120/120 positive; 392/392 negative). Similarly, examination of 1,008 tissues from 504 white-tailed deer revealed 100% concordance between the Ventana NexES and DakoCytomation platforms for diagnosing chronic wasting disease from lymphoid tissue (104/104 positive; 400/400 negative) and brainstem (104/104 positive; 400/400 negative). Examination of 1,152 tissues from 482 mule deer revealed a concordance of 98.6% in lymphoid tissue and 99.9% in brainstem between the Ventana NexES and DakoCytomation platforms for diagnosing chronic wasting disease. The results indicate equivalence or near equivalence between the DakoCytomation and Ventana NexES autostainer platforms for identification of the disease-associated prion protein (PrPd)-positive and PrPd-negative brain and lymphoid tissues in sheep, white-tailed deer, and mule deer.

Chronic wasting disease of cervids.

Chronic wasting disease (CWD) has recently emerged in North America as an important prion disease of captive and free-ranging cervids (species in the deer family). CWD is the only recognized transmissible spongiform encephalopathy (TSE) affecting free-ranging species. Three cervid species, mule deer (Odocoileus hemionus), white-tailed deer (O. virginianus), and Rocky Mountain elk (Cervus elaphus nelsoni), are the only known natural hosts of CWD. Endemic CWD is well established in southern Wyoming and northern Colorado, and has been present in this 'core area' for two decades or more. Apparently CWD has also infected farmed cervids in numerous jurisdictions, and has probably been endemic in North America's farmed deer and elk for well over a decade. Several free-ranging foci distant to the Colorado-Wyoming core area have been discovered since 2000, and new or intensified surveillance may well identify even more foci of infection. Whether all of the identified captive and free-ranging foci are connected via a common original exposure source remains undetermined. Some of this recently observed 'spread' may be attributable to improved detection or natural movements of infected deer and elk, but more distant range extensions are more likely caused by movements of infected captive deer and elk in commerce, or by some yet unidentified exposure risk factor. Research on CWD over the last 5 years has resulted in a more complete understanding of its pathogenesis and epidemiology. CWD is infectious, transmitting horizontally from infected to susceptible cervids. Early accumulation of PrP(CWD) in alimentary tract-associated lymphoid tissues during incubation suggests agent shedding in feces or saliva as plausible transmission routes. Residual infectivity in contaminated environments also appears to be important in sustaining epidemics. Improved tests allow CWD to be reliably diagnosed long before clinical signs appear. Implications of CWD are not entirely clear at this time. Natural transmission to humans or traditional domestic livestock seems relatively unlikely, but the possibility still evokes public concerns; impacts on wildlife resources have not been determined. Consequently, where CWD is not known to occur surveillance programs and regulations that prevent or reduce the likelihood that CWD will be introduced into these jurisdictions should be encouraged. Where CWD is known to occur, affected jurisdictions are conducting surveillance to estimate and monitor trends in geographic distribution and prevalence, managing deer and elk populations in attempts to limit spread, and developing and evaluating techniques for further controlling and perhaps eradicating CWD. Programs for addressing the challenges of CWD management will require interagency cooperation, commitment of funds and personnel, and applied research. Chronic wasting disease (CWD) is perhaps the most enigmatic of the naturally occurring prion diseases. Although recognized as a transmissible spongiform encephalopathy (TSE) since the late 1970s (Williams and Young 1980, 1982), interest in and concern about CWD has only recently emerged. CWD most closely resembles scrapie in sheep in most respects, but recent media and public reaction to CWD has been more reminiscent of that afforded to bovine spongiform encephalopathy (BSE) less than a decade ago. Yet, with the exception of transmissible mink encephalopathy (TME), CWD is the rarest of the known animal TSEs: fewer than 1,000 cases have been diagnosed worldwide, and all but two of these occurred in North America. CWD is unique among the TSEs in that it affects free-living species (Spraker et al. 1997; Miller et al. 2000). The three natural host species for CWD, mule deer (Odocoileus hemionus), white-tailed deer (O. virginianus), and Rocky Mountain elk (Cervus elaphus nelsoni), are all in the family Cervidae and native to North America. Like scrapie, CWD is contagious: epidemics are self-sustaining in both captive and free-ranging cervid populations (Miller et al. 1998, 2000). The geographic extent of endemic CWD in free-ranging wildlife was initially thought to be quite limited and its natural rate of expansion slow; however, recent investigations have revealed that CWD has been inadvertently spread much more widely via market-driven movements of infected, farmed elk and deer. Both the ecological and economic consequences of CWD and its spread remain to be determined; moreover, public health implications remain a question of intense interest. Here, we review current understanding of CWD, its implications, and its management.

Distinct and interactive effects of d-amphetamine and haloperidol on levels of neurotensin and its mRNA in subterritories in the dorsal and ventral striatum of the rat.

Striatal tissue concentrations of neurotensin, expression of neurotensin/neuromedin N (NT/N) mRNA, and numbers of neurotensin-immunoreactive neurons are increased by d-amphetamine (amph), which stimulates dopamine release in the striatum, and haloperidol (hal), a dopamine receptor antagonist with high affinity for D2-like receptors. The possibility that the effects of these drugs involve distinct subpopulations of striatal neurons was addressed in this study, in which the relative numbers and distributions of striatal neuron profiles containing neurotensin immunoreactivity and/or NT/N mRNA were compared following administrations of hal, amph, hal and amph co-administered, and vehicle. Fourteen striatal subterritories in caudate-putamen, nucleus accumbens, and olfactory tubercle were evaluated. Amph produced increases in the expression of neurotensin preferentially in the ventromedial and caudodorsal subterritories of the caudate-putamen, the rostrobasal cell cluster and lateral shell of the nucleus accumbens, and the olfactory tubercle. Haloperidol produced increased neurotensin expression in much of dorsal and ventral striatum, most prominently in the rostral, dorsomedial and ventrolateral quadrants of the caudate-putamen, and in the rostrobasal cell cluster, rostral pole, medial and lateral shell of the nucleus accumbens and the olfactory tubercle. The numbers of neurons responding to amph and hal in all subterritories following co-administration of the two drugs were significantly less than the summed numbers responding individually to amph and hal. Furthermore, in the subterritories where immunohistochemically detectable responses elicited by amph exceeded those produced by hal, co-administration of the two drugs resulted in responses comparable to those elicited by hal given alone. It is suggested that some of the reported anti-dopaminergic behavioral effects of basal ganglia neurotensin may be attenuated in conditions of reduced dopamine neurotransmission.

Prolongation of proton spin lattice relaxation times in regionally ischemic tissue from dog hearts.

Proton NMR techniques were used to characterize acutely ischemic myocardial tissue from the dog. Ligation of the left anterior descending coronary artery for 30 min resulted in a consistent prolongation of the proton spin-lattice relaxation times (T1) in samples from regionally ischemic heart muscle when compared with T1 values for nonischemic areas from the same hearts. The relative prolongation of relaxation times in ischemic tissue was found to increase as the duration of ischemia was extended to 60 or 120 min. T1 values for ischemic tissue were not directly related to tissue levels of high-energy compounds, lactate, or hydrogen ions but largely reflected the increased water content of the regionally ischemic myocardium. Proton NMR analysis provides a means of identifying acute regional ischemia in heart tissue, and in the future may permit three-dimensional imaging of the heart in vivo.

Early recovery of regional left ventricular function after reperfusion in acute myocardial infarction assessed by serial two-dimensional echocardiography.

Although global and regional left ventricular (LV) function has been demonstrated to improve after reperfusion in acute myocardial infarction (AMI), the timing of these changes has not been well established. In this study, serial 2-dimensional echocardiography was used to assess regional LV function in 23 patients with AMI in whom reperfusion was accomplished by thrombolysis alone, by coronary angioplasty alone or by both interventions within 6 hours after onset of chest pain. Echocardiograms were performed before or within 6 hours after reperfusion (n = 23) and at 1 (n = 19), 3 (n = 21) and 7 (n = 20) days after reperfusion. Wall motion index and percentage of normally functioning muscle were calculated using a 16-segment scoring system analyzed in blinded fashion without knowledge of patient identity, therapy or time of study. The mean wall motion index improved from 1.78 +/- 0.48 to 1.56 +/- 0.38 at 1 day (n = 19, p less than 0.01), and to 1.48 +/- 0.37 at 3-7 days (p less than 0.01), with no significant difference between 3 days (1.49 +/- 0.39) and 7 days (1.42 +/- 0.30). There was a corresponding improvement in the percentage of normally functioning muscle, from 53 +/- 24% at 6 hours to 62 +/- 20% at 1 day (p less than 0.05) and to 67 +/- 18% at 3-7 days (p less than 0.01), again with no significant difference between 3 days (67 +/- 21) and 7 days (70 +/- 20).(ABSTRACT TRUNCATED AT 250 WORDS)

Ingestion of Neospora caninum tissue cysts by Mustela species.

Dogs are a definitive host of Neospora caninum, a protozoal parasite that causes abortion in cattle. Mustelids were tested to determine if they could also be definitive hosts. The procedures used were the same as those previously used to test dogs. Ermine (Mustela erminea), weasels (Mustela frenata) and ferrets (Mustela putorius) were fed N. caninum-infected mice. Neospora caninum oocysts were not observed. Mustelid faeces were fed to mice. The mice did not seroconvert and N. caninum was not detected in murine brains using tissue culture and PCR. The hypothesis that Mustela spp. are definitive hosts of N. caninum is not supported.

Temporal dissociation of neurotensin/neuromedin N mRNA expression in topographically separate subsets of rat striatal neurons following administration of haloperidol.

The expression of the neurotensin/neuromedin N gene in the rat caudate-putamen was studied at 7 and 24 h following the administration of haloperidol using a riboprobe and non-isotopic in situ hybridization histochemistry. As has been reported by others, expression of neurotensin/neuromedin N mRNA in the dorsolateral quadrant of the caudate-putamen was undetectable in controls, robust at 7 h and minimally detectable at 24 h following haloperidol administration. In the dorsomedial and ventrolateral quadrants of the caudate-putamen, barely detectable basal expression of neurotensin/neuromedin N mRNA observed in controls was conspicuously enhanced at 24 h following administration of haloperidol both in terms of numbers of hybridized neurons, which were about 200% of control values, and the amount of chromogen accumulated over individual neurons. The data are consistent with at least two subpopulations of caudate-putamen neurons in which neurotensin/neuromedin N mRNA expression is differentially regulated in response to haloperidol administration.

Desensitization and enhancement of neurotensin/neuromedin N mRNA responses in subsets of rat caudate-putamen neurons following multiple administrations of haloperidol.

Striatal neurons that respond to blockade of dopamine receptors with altered expression of neurotensin/neuromedin N mRNA were examined. Injections of haloperidol were given to rats at four or 24 h and both four and 24 h prior to sacrifice. Pair-matched controls were injected with equivalent volumes of vehicle at either 4 or 24 h prior to sacrifice. Sections of striatum were processed non-isotopically with a cRNA neurotensin/neuromedin N probe. Massive numbers of neurons exhibited hybridization in the lateral and dorsolateral caudate-putamen at 4 h. At 24 h, hybridized neurons were few in lateral and dorsolateral parts of the caudate-putamen, but more numerous in the dorsomedial and ventrolateral caudate-putamen than in controls. A second injection of haloperidol 4 h prior to sacrifice enhanced the dorsomedial/ventrolateral response, but failed to elicit substantial numbers of lateral and dorsolateral hybrids, as were observed at 4 h after one injection. Resistance of neurotensin expression to a second injection of haloperidol was selective for the lateral and dorsolateral parts of the caudate-putamen and may reflect residual blockade by haloperidol or altered DA receptors or second messengers. Sections subjected to immunohistochemical processing for neurotensin peptide and in situ hybridization with the neurotensin/neuromedin N mRNA probe exhibited numerous neurons in the dorsomedial and ventrolateral quadrants of the caudate-putamen that were double-labeled with immunoperoxidase and hybridization signals. This suggests that peptide synthesis, as opposed to decreased release of peptide, has a role in the accumulation of neurotensin immunoreactivity by dorsomedial and ventrolateral striatal neurons.

Changes in the normal range of thyroidal radioiodine uptake.

Three series of patients shown to be euthyroid but originally referred for thyroid uptake tests in vivo have been compared. In 1958-59, the ;normal' mean thyroid uptake was 23.5% and 38.2% respectively at four and 24 hours. By 1967, the mean uptakes had dropped to 20.4% and 31.6%-a significant change at both times. By 1972 there was, however, no sign of a further reduction of the mean normal values for thyroid uptake. These results are compared with changes observed in other series in the USA and elsewhere.

Calbindin-D 28kD immunofluorescence in ventral mesencephalic neurons labeled following injections of Fluoro-Gold in nucleus accumbens subterritories: inverse relationship relative to known neurotoxin vulnerabilities.

The shell and core of the nucleus accumbens exhibit different vulnerabilities to neurotoxins. Calcium binding proteins are reported to offer some neuroprotection against excitotoxicity by suppressing or buffering intracellular calcium. Differences in the distributions of the calbindin-D 28kD (CB) and calretinin (CR) might be related to the different vulnerabilities to neurotoxins of dopaminergic neurons in the ventral mesencephalon that project to the core and medial shell of the nucleus accumbens. To address this possibility, Fluoro-Gold (FG) was injected into accumbens subterritories and numbers of retrogradely labeled neurons in the ventral tegmental area containing CB and CR immunoreactivities (ir) were expressed as a percentage of total numbers of labeled neurons. The perikaryal diameters and lengths of the immunoreactive dendrites of FG labeled neurons were also measured. About 70% and 35% of retrogradely labeled cells observed following core and medial shell injections, respectively, exhibited CB immunoreactivity. Differences were not observed in the percentages of FG labeled cells exhibiting CR immunoreactivity following medial shell (13%) and core (15%) injections. The mean perikaryal diameters and median summed lengths of dendrites of retrogradely labeled neurons containing CB were smaller than in labeled neurons lacking CB following injections in both core and medial shell of the nucleus accumbens. The data indicate that the different 6-hydroxydopamine (6-OHDA) vulnerabilities of ventral mesencephalic dopaminergic neurons are not obviously related to the presence of CB and CR.

Morphometric analysis of ventral mesencephalic neurons retrogradely labeled with Fluoro-Gold following injections in the shell, core and rostral pole of the rat nucleus accumbens.

Morphologically distinct subsets of mesotelencephalic neurons were sought following retrograde transport of Fluoro-Gold from iontophoretic injections relatively restricted to the medial shell, core or rostral pole subterritories of the nucleus accumbens. The diameter and lengths of Fluoro-Gold immunolabeled dendrites of medial shell-projecting neurons were less than those of core and rostral pole-projecting neurons.

Immunolocalization of scrapie amyloid (PrP27-30) in chronic wasting disease of Rocky Mountain elk and hybrids of captive mule deer and white-tailed deer.

Scrapie amyloid-immunoreactive plaques are present in brain tissues of captive mule deer with chronic wasting disease (CWD), a progressive neurological disorder characterized neuropathologically by widespread spongiform change of the neuropil, intracytoplasmic vacuolation in neuronal perikarya and astrocytic hypertrophy and hyperplasia. We report here the immunolocalization of scrapie amyloid (PrP27-30) in plaques observed in brain tissues of Rocky Mountain elk (Cervus elaphus nelsoni) and hybrids of mule deer and white-tailed deer (Odocoileus virginianus) naturally affected with CWD. Similar findings have been shown in kuru, Creutzfeldt-Jakob disease, and Gerstmann-Sträussler syndrome in humans. Our data corroborate that CWD in Rocky Mountain elk and hybrids of mule deer and white-tailed deer belongs to the subacute spongiform virus encephalopathies (transmissible cerebral amyloidoses).

Evaluation of methodologies for small area life expectancy estimation.

STUDY OBJECTIVE: To evaluate methods for calculating life expectancy in small areas, for example, English electoral wards. DESIGN: The Monte Carlo method was used to simulate the distribution of life expectancy (and its standard error) estimates for 10 alternative life table models. The models were combinations of Chiang or Silcocks methodology, 5 or 10 year age intervals, and a final age interval of 85+, 90+, or 95+. SETTING: A hypothetical small area experiencing the population age structure and age specific mortality rates of English men 1998-2000. PARTICIPANTS: Routine mortality and population statistics for England. MAIN RESULTS: Silcocks and Chiang based models gave similar estimates of life expectancy and its standard error. For all models, life expectancy was increasingly overestimated as the simulated population size decreased. The degree of overestimation depended largely on the final age interval chosen. Life expectancy estimates of small populations are normally distributed. The standard error estimates are normally distributed for large populations but become increasingly skewed as the population size decreases. Substitution methods to compensate for the effect of zero death counts on the standard error estimate did not improve the estimate. CONCLUSIONS: It is recommended that a population years at risk of 5000 is a reasonable point above which life expectancy calculations can be performed with reasonable confidence. Implications are discussed. Within the UK, the Chiang methodology and a five year life table to 85+ is recommended, with no adjustments to age specific death counts of zero.

Proteins isolated from the venom of the common tiger snake (Notechis scutatus scutatus) promote hypotension and hemorrhage.

Notechis scutatus scutatus venom contains several toxic acidic proteins called HTa-i which promote hypotension and hemorrhage in mice. They have apparent mol. wts in the 18,000-21,000 range, i.v. LD50 values between 0.5 and 1.5 micrograms/g, and no detectable phospholipase, arginine esterase, proteolytic or hemolytic activities. A polyclonal antibody raised against HTg binds to other purified proteins, suggesting that they are isoforms of the same protein. Many other elapid crude venoms contain proteins which recognize the polyclonal antibody raised against HTg. Crotalid and viperid crude venoms do not recognize this antibody, although some of their component proteins are known to exhibit hypotensive and hemorrhagic activities. A combination of gel-filtration on Sephacryl S-200, cation-exchange and anion-exchange chromatography allows isolation of the N. s. scutatus proteins in high purity. They are the first hypotension-inducing proteins to be purified from an Australian elapid.

Isolation of calcium tolerant myocytes from adult rat hearts: review of the literature and description of a method.

Myocytes have been isolated from adult rat hearts since 1969. The early preparations exhibited the Ca2+ paradox. Over the ensuing years, numerous groups have reported the isolation of Ca2+ tolerant cardiac myocytes. In the present review, detailed comparisons have been made of the yields, viability, and relative Ca2+ tolerance of these different myocyte preparations. The factors to which these investigators attributed the increased Ca2+ tolerance are considered, and the current information regarding the mechanism of the Ca2+ paradox is reviewed. A method is given which incorporates several of the modifications described. By this method 40-60% of the ventricular weight was disaggregated into single myocytes within 45 min after the sacrifice of the rats. Viability without further purification was 82 +/- 0.7% (n = 35) and Nai+/Ki+ ratios were normal. Upon incubation with 2 mM Ca2+ for 1 hr at 37 degrees C, viability decreased by 6% and ATP and creatine phosphate remained at physiological levels. The preparation is very stable since upon incubation in culture medium containing fetal bovine serum and 1.25 mM free Ca2+ at 25 degrees C for 20 hr, viability decreased only 13% (rod-shaped and trypan blue criteria). The factors which contribute to the quality and Ca2+ tolerance of this preparation are discussed.

Radionuclide section scanning of the lungs in pulmonary embolism.

A new approach to the radionuclide imaging of the lungs is illustrated in this paper, describing four patients who were subjected to section scanning of the chest in addition to conventional planar imaging. The significance of this new method in the investigation of patients suspected of having pulmonary embolism is discussed. The main advantages of the new approach include increased information with depth, clearer definition of the mediastinal space, and the detection in some instances of new lesions not seen by conventional means.

Electron microscopic findings in brain of Rocky Mountain elk with chronic wasting disease.

We report here the electron microscopic findings in brain of Rocky Mountain elk with chronic wasting disease (CDW), a progressive and fatal neurological disorder of wild ruminants characterized neuropathologically by intraneuronal vacuolation, spongiform change of the neuropil and astrocytic hypertrophy and hyperplasia. Ultrastructural findings included membrane-bound vacuoles in neuronal elements, increased number of glial filaments, dystrophic neurites, numerous neuritic plaques, Hirano bodies and perikaryal inclusion bodies. Similar findings have been observed in CWD-affected mule deer, as well as in bovine spongiform encephalopathy, and in natural and experimental scrapie and Creutzfeldt-Jakob disease indicating a common etiopathogenesis.