The Human Spongiform Encephalopathies

Transgenic mice expressing bovine PrP with a four extra repeat octapeptide insert mutation show a spontaneous, non-transmissible, neurodegenerative disease and an expedited course of BSE infection

Transgenic (Tg) mice carrying four extra octapeptide repeats (OR) in the bovine PrP gene (10OR instead of 6) have been generated. In these mice, neuropathological changes were observed depending upon the level of transgene expression. These changes primarily involved a slowly advancing neurological disorder, characterized clinically by ataxia, and neuropathologically, by vacuolization in different brain areas, gliosis, and loss of cerebellar granule cells. Accumulation of insoluble bovine 10OR-PrP (bo10OR-PrP) was observed depending on the level of expression but no infectivity was found associated with this insoluble form. We also compared the behavior of bo6OR-PrP and bo10OR-PrP Tg mouse lines in response to BSE infection. BSE-inoculated bo10ORTg mice showed an altered course of BSE infection, reflected by reduced incubation times when compared to bo6ORTg mice expressing similar levels of the wild type 6OR-PrP. In BSE-inoculated mice, it was possible to detect PrP(res) in 100% of the animals. While insoluble bo10OR-PrP from non-inoculated bo10ORTg mice was non-infectious, brain homogenates from BSE-inoculated bo10ORTg mice were highly infectious in all the Tg mouse lines tested. This Tg mouse model constitutes a new way of understanding the pathobiology of bovine transmissible spongiform encephalopathy. Its potential applications include the assessment of new therapies against prion diseases.

Patterned Purkinje cell death in the cerebellum

The object of this review is to assemble much of the literature concerning Purkinje cell death in cerebellar pathology and to relate this to what is now known about the complex topography of the cerebellar cortex. A brief introduction to Purkinje cells, and their regionalization is provided, and then the data on Purkinje cell death in mouse models and, where appropriate, their human counterparts, have been arranged according to several broad categories--naturally-occurring and targeted mutations leading to Purkinje cell death, Purkinje cell death due to toxins, Purkinje cell death in ischemia, Purkinje cell death in infection and in inherited disorders, etc. The data reveal that cerebellar Purkinje cell death is much more topographically complex than is usually appreciated.

Clinical characteristics of chronic Creutzfeldt-Jakob disease

Chronic Creutzfeldt-Jakob disease, presenting in later life, may be difficult to distinguish from other dementing illnesses. Patients with this disease may lack the characteristic myoclonus and electroencephalographic complexes. We report four patients with a slowly progressive dementia who were misdiagnosed during life and had a spongiform encephalopathy at autopsy. All four patients had early extrapyramidal rigidity, primitive reflexes, and other neurologic signs. The presence of these neurologic findings early in the course of a dementia suggests that clinicians should consider chronic Creutzfeldt-Jakob disease, evaluate the patient with electroencephalographic studies, and emphasize universal tissue precautions.

Creutzfeld-Jakob disease: recommendations for infection control

Creutzfeld-Jakob disease, an infectious, progressive, degenerative neurologic disorder, has a presumably long incubation period but a rapid, fatal course. Brain tissue at autopsy resembles that seen in spongioform encephalopathies of other species. Creutzfeld-Jakob disease is transmitted by a proteinaceous infectious agent, or "prion." Epidemiologic patterns remain uncertain; various studies have reported conflicting risk factors in different populations, and genetic susceptibility may be involved. Although natural transmission routes are still unclear, both iatrogenic and nosocomial transmissions have been identified. Transmission has occurred through contaminated electrodes, contaminated biologic products from cadaveric brains, and infected donor tissues, including dura mater and corneas. Because the prion is difficult to eradicate, stringent sterilization precautions must be taken with all surgical instruments. Some tissues and body fluids (e.g., brain, ocular, central nervous system) from the patient with Creutzfeld-Jakob disease are highly infectious and must be contained or incinerated. Some body fluids, however, are not considered infectious. Persons with known or suspected Creutzfeld-Jakob disease, or with exposure to potential sources of iatrogenic infection, should not be considered as donors for any tissues or biologic products. Occupational transmission to health care and pathology workers is also possible. Therefore, specific preventive measures are necessary. Many questions remain regarding transmission and risk factors for Creutzfeld-Jakob syndrome, and the precautions presented here must be considered only preliminary.

Jakob-Creutzfeldt disease associated with Wernicke encephalopathy

Wernicke disease (WD) is a complication of alcoholism and malnutrition and usually presents acutely and is characterized by disturbances of consciousness, paralysis of the external ocular muscles, and ataxia. The disease results from deficiency of vitamin B 1, or thiamine, an essential coenzyme in intermediate carbohydrate metabolism. On the other hand, Jakob-Creutzfeldt disease (J-C) results from infection with an unconventional agent with a long incubation period and is characterized by a rapidly progressive dementia and histologically by a spongiform encephalopathy associated with neuronal destruction and pronounced astrogliosis. Combination of both diseases has not been reported in the literature previously and their relationship is uncertain. We present 3 cases with this interesting association and consider their relationship.