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The etiology of most human dementias is unknown. Creutzfeldt-Jakob disease (CJD), a relatively uncommon human dementia, is caused by a transmissible virus-like agent. Molecular markers that are specific for the agent have not yet been defined. However, the infectious disease can be transmitted to rodents from both brain and infected buffy coat (blood) samples. To determine whether human CJD infections are more widespread than is apparent from the low incidence of neurological disease, we attempted to transmit CJD from buffy coat samples of 30 healthy volunteers who had no family history of dementing illness. Primary transmissions from 26 of 30 individuals produced CJD-like spongiform changes in the brains of recipient hamsters at 200-500 days postinoculation. This positive evidence of viremia was found for individuals in all age groups (20-30, 40-50, and 61-71 years old), whereas 12 negatively scored brain samples failed to produce similar changes in hamsters observed for > 900 days in the same setting. We suggest that a CJD agent endemically infects humans but only infrequently produces an infectious dementia. Disease expression is likely to be influenced by several host factors in combination with viral variants that have altered neurovirulence.

Creutzfeldt-Jakob disease (CJD) is a dementia of humans caused by a class of infectious agents with several biological properties similar to those of conventional viruses. The molecular nature of this group of agents is enigmatic, for neither an agent-specific nucleic acid nor a non-host protein has yet been identified. Recent transmissions of familial CJD dementias to rodents suggest that this class of agent can be integrated into the germline. Furthermore, tissue culture studies indicate that CJD causes transformation of cells in a manner reminiscent of slowly oncogenic retroviruses. Currently characterized retroviral-like elements include many forms that do not have 'typical' retroviral ultrastructural morphology; several forms are also known to be resistant to various types of standard physicochemical inactivation. We suggest that CJD agents are either constituted by retroviral-like nucleic acids or interact with endogenous retroviral sequences to elicit a slowly progressive disease of the central nervous system. Several overlapping properties between infectious CJD and 'non-infectious' dementias, such as Alzheimer's disease, implicate potential common pathogenic mechanisms.

Experimental Creutzfeldt-Jakob disease was serially transmitted from guinea pigs to Syrian hamsters with 100% incidence, morbidity, and mortality. All animals developed a subacute spongiform virus encephalopathy with neuronal destruction and concomitant astrocytic changes. In the first passage three different clinical syndromes were recorded, each with widely variant incubation times; these results suggested there may be different strains of the Creutzfeldt-Jakob agent, some of which may be partially separated when the agent is passaged from one species to another. Accumulations of neurofilaments in neuronal perikarya and processes and increased lipofuscin were suggestive of changes seen in senility and aging.

Phrenic nerves were obtained at autopsy from 7 patients with chronic ventilatory insufficiency. One or both nerves had been subjected to electrical stimulation to pace the diaphragm for about 2 months to 4 years. Sections of the nerves made from above, at the level of, and below the site of application of the cuff electrode were studied microscopically. In most specimens, focal areas of demyelination were seen ranging in severity from swelling and fragmentation of isolated fibers to focal myelin destruction with phagocytic activity and total removal of myelin with fibrosis. Some axone loss was seen. The fact that the nerves from 2 patients, each stimulated for about 2 years, showed no changes suggests that injury to the nerve was not caused by the electrical stimuli but rather was secondary to the technique of application and fixation of the cuff electrode to the nerve.

An electron microscopic study was done on brain biopsy tissue from an eight-month-old female with acute eastern equine encephalitis diagnosed by indirect immunofluorescence. Rare clusters of round virions were found almost exclusively in the extracellular space. All virions observed had spiked envelopes, and their sizes averaged approximately 55 nm. Also found were rare enveloped virions along with degenerate organelles in a membrane-bound structure in the cytoplasm of macrophages. Intracytoplasmic development of virions was not found. Tubuloreticular complexes were seen in the endothelial cells and macrophages. This is the first report of an electron microscopic study on biopsy material from a case of human eastern equine encephalitis. It will extend the usefulness of brain biopsy in the diagnosis of acute encephalitis.

Significant proliferation of capillaries with hyperplastic vascular endothelium is one of the characteristic histologic features of glioblastoma multiforme (GBM). It has been shown that the renin-angiotensin II cascade stimulates new vessel formation. The presence of renin in several types of highly vascularized neoplasm suggests that it may also be implicated in the mechanism of tumor angiogenesis. In order to study the possible relationship of renin to GBM, immunohistochemical search for human renin was carried out in ten instances of such a tumor. Eight of these cases demonstrated renin-containing neoplastic astrocytes, whereas seven cases of reactive gliosis and six cases of low-grade astrocytoma revealed no renin-containing cells. The immunostaining was not present after preabsorption of the renin antiserum with pure human renin or substitution of preimmune serum for the specific renin antiserum. Because it has also been demonstrated that a product of renin, angiotensin II, has angiogenic properties, it seems reasonable to postulate that renin, through angiotensin II, may play a role in the mechanism of GBM-associated neovascularization.

Small amounts of brain tissue (2 g) infected with Creutzfeldt-Jakob disease (CJD) can be fractionated by using a simple 1-day method that includes lysis with N-lauroylsarcosine. Unique fibrils have been identified previously in scrapie- and CJD-infected tissue. These fibrils were abundant in final fractions. Preparations from human CJD autopsy material and from experimental hamster and guinea pig CJD all displayed readily identifiable fibrils that were not seen in control preparations. Thus, these methods appear to be of value in biopsy diagnosis of suspected human cases of CJD. Lysis with N-lauroylsarcosine quantitatively solubilized infectivity from membrane-rich fractions. Significant infectivity was recovered in microfractionations. After proteinase K digestion, a diffuse band at 29 kDa was detectable on NaDodSO4/PAGE. This 29-kDa material was not present in uninfected control brain and was similar to that seen in scrapie. Protein blots of human, guinea pig, and hamster CJD fractions were tested with an antibody raised against a 29-kDa band from mouse scrapie; 29-kDa proteins were labeled in all CJD and scrapie fractions but not in controls. These results indicate that specific proteins in both these diseases share common antigenic determinants. Ricin and wheat germ agglutinin, but not concanavalin A, also labeled a portion of the 29-kDa band from hamster CJD and hamster scrapie fractions, but they did not label any bands in normal hamster fractions at the same gel protein loads. When proteinase K treatment was omitted, specific bands of approximately equal to 35 kDa were detected in CJD samples. These results are consistent with the idea that some CJD- and scrapie-specific proteins are glycoproteins or sialoglycoproteins that can reside in or possibly derive from cell membranes.

Brains from six clinically ill guinea pigs from various serial passages infected with brain homogenate from a patient with Creutzfeldt-Jakob disease were studied by light and electron microscopy. There were no appreciable morphologic differences among the animals at different passages. Light microscopy revealed clearing, swelling, and vacuolar changes in neurons and astrocytes. These changes occurred in both perikarya and cell processes. Large isolated vacuoles in the neuropil appeared to develop by progressive fusion between swollen cellular processes. By electron microscopy many neuronal processes contained degenerating organelles, osmiophilic bodies, membranous bodies and approximately 10 mm filamentous structures. In addition, vacuoles and membranous inclusions were seen in some neuronal nuclei, changes which have not been previously observed in spongiform encephalopathies.

Gangliosides were isolated from guinea pig brains at the end stages of experimental Creutzfeldt-Jakob disease. Quantitative analyses revealed marked decreases of ganglioside levels in pathologically devastated tissues such as cerebral cortex (−21%), basal ganglia and thalamus (−18%), and brain stem (−23%). The cerebellum revealed only minor pathological abnormalities and its ganglioside level remained unchanged. Thin-layer chromatography of the Creutzfeldt-Jakob brain gangliosides showed aberrant ganglioside patterns in all regions studied, including the cerebellum. With some exceptions, a trend in ganglioside pattern changes was detected which consisted of proliferation of G M3 , G D3 , G D2 and loss of G M1 , G D1a , G D1b and G T1b ∗∗ .

The quantitative preservation of satellite NA was studied in several central nervous system (CNS) neoplasms; four tumor lines deriveo from 3-methylcholanthrene implantation into the CNS of mice were compared with brain and tissue cultures of normal mouse cells by analytical centrifugation in cesium chlorie. Three tumors showed no detectable difference from normal cells; nuclear and whole cell preparations were comparable. Only a glioblastoma line proucing C-type particles (TC509) revealed a significant difference from normal cells and exhibited a decrease of approximately 20% in satellite DNA or 2% of the total DNA on repeated examination for 1 year. C-type RNA virus may be related to relative decreases in satellite DNA observed in TC509.

Newborn rats were administered 3H-thymidine, 3H-thymine, 3H-adenine, or 3H-cytidine every 6–8 hr. from neonatal day four to day ten. Utilizing autoradiography, cerebellar Purkinje cells showed little or no nuclear label with 3H-thymidine or 3H-cytidine, although other cells known to divice postnatally (e.g., granule and glial cells) did incorporate these precursors into DNA. The few nuclear grains seen over Purkinje cells with 3H-cytidine were not seen if the fixed tissue was first digested with RNAase. 3H-thymine and 3H-adenine were not incorporated into any cerebellar cells including Purkinje cells in vivo despite the administration of equivalent or higher doses of these isotopes. Purkinje cells had undergone their major morphological maturation during the period of isotope exposure. Organotypic explants of newborn rat cerebellum also failed to display uptake of 3H-thymidine in Purkinje cells during continuous exposures for the first 18 days in vitro. 3H-thymine showed no clearcut labelling of Purkinje cells when cultures were labelled for the first 13 days in vitro; this in vitro method excluded the possibility that 3H-thymine had not been taken up in vivo because of permeability factors or excessive metabolism by other organs. The above results do not support the notion of development of early Purkinje cell “tetraploidy” obtained by Feulgen microdensitometry.

The transmission and serial propagation of Creutzfeldt-Jakob disease from man to guinea pigs are reported. The latency, symptomatology, and morphology of the infection during the first four passages are presented. The incubation period between the first and subsequent passages was halved. One hundred percent take, morbidity, and mortality were achieved in all inoculated animals. All guinea pigs developed a subacute spongiform virus encephalopathy with marked neuronal destruction in the cerebral cortex and subcortical grey structures. The neuronal loss resulted in cerebral atrophy and hydrocephalus ex vacuo.

The historical aspects of spongiform encephalopathies, Creutzfeldt-Jakob disease (CJD) and kuru of man, as well as scrapie and transmissible mink encephalopathy, are outlined. Transmissions of these diseases to animal hosts are presented, with emphasis on CJD transmissions to guinea pigs, hamsters, and mice. The relationship of CJD to scrapie with reference to the pathological findings is discussed. In CJD the incubation period is cut in half in guinea pigs and hamsters in the second passage. The spongiform changes occurring in the neuropil are reviewed. These changes are related to the type of inoculum, e.g., there is more vacuolization after inoculation with brain, and less after inoculation with spleen. Spongiform changes are also dependent upon the route of inoculation; these are more severe in intracerebral inoculation compared to intraperitoneal inoculation. Viremia is present. Maternal transmission and lateral transmission are absent. No virus-like particles are detected, and no other organisms are visible by electron microscopy. Isolations of the causative agent and strains of the agent in spongiform encephalopathies remain elusive. The hypotheses concerning the nature of the agent are critically reviewed. Novel data on the production of tumors derived from CJD brains are presented. Tissue culture cells arising from such brains become permanent lines and are similar to neoplastic lines. When such CJD lines are injected subcutaneously into nude mice, malignant neoplasms are formed. No evidence of an infectious etiology in Alzheimer's disease exists. Reported similarities between this disease and CJD are reviewed. Animal models of CJD are useful for the investigation of dementias.

Cholera toxin was coupled to peroxidase to yield a highly specific ultrastructural marker for Gm1 gangliosides. Study of embryonic brain cells in culture revealed intense binding of choleraperoxidase by plasma membranes of both neurons and glial cells. In contrast, long-term monolayer glioblastoma cultures, including one producing C-type virus, revealed virtually no labelling of their plasma membranes. Such cells were shown to be capable of incorporating exogenously applied Gm 1 into their plasma membranes. Studies with fixed brain and synaptosomal fractions were in accord with results on embryonic brain cells in culture, and autoradiographic findings with125I cholera supported observations made utilizing cholera—peroxidase. From our studies there is some indication that long-term propagation in vitro alters the plasma membrane Gm1.

A series of human neuroectodermal tumors, all containing more than the normal diploid DNA, and each with its own distinct chromosome mode, were studied using restriction enzyme cleavage and specific DNA sequence hybridization. Methods described were quite sensitive and quantitative and as few as 40 molecules with a given restriction site were reproducibly detected in total nuclear DNA. Analysis of several fluorescent gel bands associated with different chromosomal domains revealed no changes between any of the tumor and normal cells. Specific probe hybridization, using purified complex repeating sequences, indicated fidelity of base sequence, as well as preservation of the relative amounts of each of a number of minor related multimers in both the tumor and normal cells. Centromeric regions containing arrays of such sequences may be maintained in these tumor cells and furthermore it is possible that some of these cells are polyploid with respect to DNA sequences, rather than aneuploid as their chromosome profiles suggest.

✓ A case is presented with the acute development of a pineal region syndrome secondary to hemorrhage into a pineal cyst in a patient who was under anticoagulant therapy. Resolution of the symptoms and signs followed excision of the lesion.

Bei der Teschener Krankheit des Schweines handelt es sich um eine durch ein spezifisches neurotropes Virus hervorgerufene Encephalomyelitis. Die erkrankten Tiere zeigen klinisch Fieber, Unruhe, Appetitlosigkeit, Opisthotonus und Krampfe; ferner Tremor, Zwangsbewegungen, Nystagmus, Gleichgewichtsstorungen, Ataxie und Lahmung der Extremitaten. Meist fuhrt die Krankheit zum Tode. Das klinische Bild weicht in mehrfacher Beziehung von dem der Poliomyelitis ab. Eine im Laufe der Erkrankung zunehmende Meningitis ist schon in den fruhesten Stadien nachweisbar. Sie ist ortlich sehr Verschieden ausgepragt. Eine massive lymphoplasmocytare Infiltration ist uber dem Kleinhirn vorhanden, uber den Groshirnhemispharen erreicht sie mittlere Grade und am Ruckenmark und Medulla oblongata ist so gut wie gar nichts zu sehen.

Occlusion of cerebral capillaries due to acute swelling of the endothelial cells has been demonstrated in the brains of turkeys with encephalopathy caused by Mycoplasma gallisepticum (S-6 strain) infection. Similar capillary lesions were seen in rats with rolling disease, caused by M. neurolyticum toxin. Such lesions may be the basis of ischemic necrosis of the brain.

S INCE 19~5 at tempts have been made to prepare tissue cultures from neoplasms of the central nervous system. Fischer 3 was the first to report viability of malignant glial tumors in tissue cultures for a period of months. Most reports have dealt with short-term tissue cultures, and few observations have been described dealing with longterm, permanent lines of tissue cultures. The latter easily permit both qualitative and quanti tat ive studies, such as heterologous transplantat ion of the lines, 7,s evaluation of the effects of changes in experimental environment, 9 virological investigations, 's and, in general, allow the observer to examine " the dynamic properties and the modulation in form with the passage of time. ''6 In this laboratory, many permanent longterm tissue cultures have been established successfully; the oldest, dating to September 1957, continues to grow. TM I t is the purpose of this communication to describe a relat ively simple technique of long-term monolayer culturing of tissue by means of which several glial and nonglial neoplastic lines can be, and have been, propagated for long periods of time.

Summary The behavior of the Russian AB IV strain of virus has been observed in mice, chimpanzees and monkeys. The observations of Johnsson and Lundmark (2) and Habel and Loomis (3) that this strain is immunologically identical with Coxsackie A-7 virus and produces characteristic muscle lesions in mice, have been confirmed. It was established, furthermore, that the agent responsible for paralysis in monkeys is also neutralized by Coxsackie A-7 antiserum. Inapparent infection was produced in 2 chimpanzees fed the virus. Nine CNS passages in monkeys have been carried out, and many levels of the CNS of monkeys from passages 1 through 6 have been studied. The disease in monkeys resembles mild paralytic poliomyelitis. Histologically the lesions are similar to those produced by polioviruses, but in general milder in degree, and less restricted in their distribution in the forebrain: certain areas such as the corpus striatum and the temporal and occipital lobes of the cerebral cortex which are rarely, if ever, involved in poliomyelitis, show mild lesions with considerable regularity with the Russian strain of virus. The Russian strain is concluded to be a member of the A-7 group of Coxsackie viruses which has certain unusual but not unique properties, and in its behavior falls somewhere between the usual Coxsackie and polioviruses.

Twenty two cases of cerebral and so-called cerebellar astrocytomas were heterologously transplanted to guinea pigs. Although the fifteen cerebral astrocytomas were selected according to optimal conditions for transplantation, all failed to grow heterologously. The cerebral astrocytomas represent varieties of fibrillary, protoplasmic and pilocytic types, and all originated in adults. Of the seven randomly selected so-called cerebellar astrocytomas, all of which occurred in children, only one grew when transplanted intracerebrally to guinea pigs. This tumor before transplantation had all the histological characteristics of a so-called cerebellar astrocytoma. The prevailing cells were elongated, spongioblast-like elements; however, other cell types, e.g., astrocytes occurred in varying numbers. The heterotransplant was dominated by elongated, mostly bipolar cells with a very characteristic cytoarchitectural arrangement. The controversy regarding classification of cerebellar astrocytomas versus cerebellar spongioblastomas was discussed. Although the name “spongioblastoma” is not favored, the concept of classifying the so-called cerebellar astrocytoma together with other slow growing midline gliomas as proposed by Zulch has definite merits. Heterotransplantation studies clearly demonstrate that the so-called cerebellar astrocytoma has different biological properties than cerebral astrocytomas.

Cholera toxin coupled to peroxidase yielded a highly specific ultrastructural marker of plasma membrane monosialogangliosides. Studies with cultures of brain and brain tumors suggested that long-term culture of tissue in monolayers results in eventual loss of surface monosialogangliosides.

Inoculation of the buffy coat of blood from guinea pigs infected with Creutzfeldt-Jakob disease resulted in passage of this disease to recipient animals. This demonstrates that there is a viremia in experimental Creutzfeldt-Jakob disease. These findings suggest that the hematogenous route may be implicated in the human infection and that the disease may possibly be transmitted by blood transfusions.

Scrapie of sheep, transmissible mink encephalopathy and Creutzfeldt-Jakob disease and kuru of man constitute the nosologic group of subacute spongiform virus encephalopathies.1 The possible transmi...

SummaryA line of tissue culture cells originally arising from a histologically verified human case of glioblastoma multiforme has been propagated in continuous subcultures for approximately 2 years. Morphological characteristics and preliminary observations concerning susceptibility of these cells to viruses are given. Rate of growth was measured by nuclei count and total protein determination and was compared with rate of growth of HeLa cells under identical conditions.

Gliosis (hyperplasia and hypertrophy of astrocytes), the fundamental response of the central nervous system to tissue destruction, typically becomes apparent only several weeks after injury. The biochemical hallmark of this response is a marked accumulation of the specific astrocyte intermediate filament glial fibrillary acidic protein (GFAP). To date despite its importance, the mechanisms of GFAP gene regulation have not been studied in any developmental or pathological system to our knowledge, and the molecular signals for GFAP mRNA and protein accumulation are not defined. In Creutzfeldt-Jakob disease, a progressive dementing illness caused by an "unconventional agent," we find steadily increasing elevations of GFAP mRNA throughout the later stages of disease, using two independent GFAP cDNA clones, representing the entire insert or the 3'-noncoding region (pScr-1). The accumulation of GFAP, assessed immunocytochemically, follows GFAP mRNA elevation. A 5-fold stimulation of GFAP gene expression precedes the development of florid histologic lesions in the cerebrum, and in the cerebellum 5- to 6-fold increases occurred with no detectable spongiform changes at any time during disease. Therefore, these GFAP changes cannot be simply a response to neuronal damage. These effects are directly or indirectly caused by high local concentrations of agent and possibly involve a humoral factor.

Cells from a human glioblastoma (TC 526) maintained in tissue culture for ten years had a mean membrane potential of 27 +/- 0.9 mV at an external potassium concentration [Ko] of 5.3 mM. When [Ko] was varied between 2.5 and 5.3 mM, membrane potential changes were close to those predicted by the Nernst equation. At higher [Ko], the Nernstian slope was approached only in the presence of 10(-5) M ouabain, which did not affect membrane potential at a [Ko] of 5.3 mM. An electrogenic sodium pump activated by high [Ko] could explain these findings; such a mechanism has been demonstrated in other tissues.

Congenital cerebellar medulloblastoma is extremely rare. Reported here is a female infant who presented her first abnormal clinical manifestations on the sixth day of life and who was subsequently found to have medulloblastoma at operation. Electron microscopy revealed glial filaments and short cytoplasmic projections in some neo-plastic cells and the presence of junctional complexes between neoplastic cells with and without glial filaments, which suggests the astrocytic differentiation of the tumor. Including our own case, there have been only 21 reported cases of congenital cerebellar medulloblastoma. A strong female preponderance and some familial occurrence are noted in congenital cerebellar medulloblastoma

Creutzfeldt-Jakob disease is a slow, infectious, progressive neurological disorder which results in human dementia. Synaptic membranes from various brain regions of guinea pigs infected with Creutzfeldt-Jakob disease show increased guanyl nucleotide- or 5-hydroxytryptamine-mediated activation of adenylate cyclase. This increased enzyme activity appears due, primarily, to facilitated ‘coupling’ between the GTP-binding protein which stimulates adenylate cyclase (GN s ) and the catalytic moiety of that enzyme rather than increased sensitivity to 5-hydroxytryptamine. It is possible that this phenomenon is due to direct effects of the Creutzfeldt-Jakob infectious agent, or a pathological product resulting from that agent, upon synaptic membrane adenylate cyclase.

The chromosomal localization of satellite DNA in two tissue culture lines derived -rom malignant mouse CNS tumors was investigated by in situ hybridization of 3H single-stranded satellite DNA purified by isopynic centrifugation in alkaline CSC1. Both tumors were glioblastomas originally induced by a methylcholanthrene implantation into the cerebrum of C3H mice; both displayed aneuploid chromosomal constitutions. One of these glioblastomas (TC 541) revealed labelling only of centromeric portions of the chromosomes even in cells containing greater than 200 chromosomes and thus it had a pattern of satellite distribution comparable to that of normal cells. The other glioblastoma (TC 509), that produced C-type particles and had a decrease in satellite DNA, displayed interstitial and telomeric label in some chromosomes in addition to labelling of the centromeres. "Hoechst 33258" fluorescence showed some interstitial and telomeric bright bands as well as centromeric bright regions, though to be consistent with in situ studies. The localization of satellite DNA to the chromosome arms and its possible relation to C-type virus is discussed.

In a 53-year-old man with a progressive mental deterioration and myoclonic jerks, brain biopsy failed to show any significant light microscopical findings. Electron microscopy revealed membrane-bound vacuolar inclusions in many neuronal nuclei as the only prominent finding. Hamsters intracerebrally inoculated with the biopsy material demonstrated typical spongiform changes in the gray structures of the brain when sacrificed on the 309th and 332nd days post inoculation, characteristic of experimental Creutzfeldt-Jakob disease (CJD). These intranuclear vacuolar inclusions, originally reported in experimental Creutzfeldt-Jakob disease in this laboratory, may be a valuable electron microscopic feature in some CJD cases and may play an important role in supporting the diagnosis of CJD.

Guinea pigs inoculated with brain homogenate from serially passaged Creutzfeldt-Jakob disease (CJD) were killed biweekly starting at week 2 until terminal illness (about 200 days following inoculation). A mild swelling of postsynaptic dendrites and an increase in the number of glial filaments in astrocytic processes was seen at week 4, followed by increased swelling and lucency of axons and dendrites by week 6 post inoculation (p.i.). Severe undulation and focal interruptions of synaptic membranes were also observed both at weeks 4 and 6. By week 8, one could see cystically dilated cellular processes. These sometimes showed continuity with adjacent swollen processes through focally disrupted plasma membranes, and most likely represent a progressive enlargement of vacuoles through fusion and subsequent addition of adjoining processes. The spongiform changes increased mildly between week 8 and week 10 and remained essentially the same in subsequent weeks. After week 24 there was a sharp increase in both the number and size of vacuoles. At week 24 severe structural alterations were present both in the neurons and astrocytes, and numerous intranuclear inclusions were demonstrated in many neuronal nuclei. This study shows that morphological changes in the brain occur considerably earlier than the clinical manifestations of the disease. In the early phase of the disease, there were significant alterations on the dendrites and synapses.

Scrapie agent has been reported to contain an “essential DNA” component in the viroid size range (R. F. Marsh, T. B. Malone, J. S. Semancik, W. D. Lancaster, and R. P. Hanson, Nature (London) 275, 146–147, 1978). The human transmissible encephalopathy, Creutzfeldt-Jakob disease (CJ) was searched for unique CJ DNA components in highly infectious brain fractions containing negligible amounts of nuclear DNA. DNA was quantitatively extracted from these fractions and labeled to high specific activity by “nick translation” with 32 P-nucleotides under conditions where the labeled DNA maintained its original length. Labeled DNAs were analyzed by gel electrophoresis with special emphasis on molecules in the viroid size range. Reconstruction experiments showed that ⩽0.1 pg DNA could be detected with these procedures. No reproducible CJ specific DNA bands were detectable when compared to normal brain fractions. Restriction enzyme analysis of these DNAs also showed no CJ specific bands integrated into larger molecular weight DNA. Use of Brij 58 to release more infective physical particles into the rough endoplasmic reticulum also did not show CJ specific DNAs. Comparison of the amounts of known infective units by animal assay, assuming a 400-base DNA sequence, indicated that CJ specific DNAs should be detectable in these fractions with the methods used. These results appear to rule out usual forms of double-stranded or partially double-stranded DNAs as components of transmissible encephalopathy agents. A systematic analysis of other specific nucleic acid components of these agents is feasible using the highly sensitive in vitro labeling approach employed here.

The etiology of Alzheimer disease (AD) is unknown. To investigate the transmissibility of AD, the buffy coat of the blood from 11 relatives of AD patients, including 2 with suspicious or early signs of AD, was inoculated intracerebrally into hamsters. In these pilot experiments, 5 individuals produced histologically documented spongiform encephalopathy on primary passage in recipient hamsters. Material from 3 of these positives was serially transmitted in a second passage. The histological alterations observed in the brains of positive hamsters were similar to those seen in experimental Creutzfeldt-Jakob disease (CJD). These transmission results raise the intriguing possibility that CJD-like agents may be involved in at least some forms of AD.

Isolates from six patients with Creutzfeldt-Jakob disease (CJD) were injected into various strains of hamsters and mice, and the infective agent was propagated. Serially passaged cultures were established from these CJD agent-infected brains and from uninfected control brains. All healthy cultures (21 out of 21) from CJD agent-infected brains became immortal and/or transformed. In contrast only 3 out of 13 normal brain cultures became immortal, and the rest died out with serial propagation in vitro. The fact that permanent cell lines were readily derived from multiple rodent strains and all CJD isolates tested suggests that a transforming capability is an intrinsic property of CJD agents. This conclusion is supported by demonstrations of in vitro cell transformation by CJD infectious brain fractions. Although the molecular mechanism of transformation events associated with the CJD agent is not presently known, a provocative possibility is that the CJD agent has a direct effect on the host genome by mechanisms analogous to those known for slowly oncogenic retroviruses.

The ganglioside level and pattern of human gliomas in monolayer cultures were examined. These gliomas revealed morphological variations that correlated with several features of ganglioside analysis. Glioblastoma lines TC 178 and TC 501 that morphologically had changed during extended subculture revealed reduced amounts and a simplified pattern of gangliosides with almost total loss of the characteristic brain complex gangliosides. In contrast, two glioblastoma lines TC 526 and TC 593, as well as the oligodendroglioma line TC 620 showed brain-like gangliosides and the cells in these cultures had maintained their characteristic morphology observed during early subcultures. The possibility that altered ganglioside levels occur in conjunction with morphological changes after propagation in vitro is discussed.

Several lines of investigation identify common features of Creutzfeldt-Jakob disease, Alzheimer disease, and retroviral CNS infections. We discuss salient neuropathological, genetic, transmission, and transformation properties that suggest there may be common pathways in the pathogenesis of dementias. We also briefly present potential retroviral mechanisms that may be implicated in all of these dementias.

In the broad context of dementing disease, a brief overview of infectious, biological, genetic and physical properties of these agents is presented