Therapeutic effect of CHF5074, a new γ-secretase modulator, in a mouse model of scrapie.

In Transmissible Spongiform Encephalopathies (TSEs) and Alzheimer disease (AD) both misfolding and aggregation of specific proteins represent key features. Recently, it was observed that PrP (c) is a mediator of a synaptic dysfunction induced by Aß oligomers. We tested a novel γ secretase modulator (CHF5074) in a murine model of prion disease. Groups of female mice were intracerebrally or intraperitoneally infected with the mouse-adapted Rocky Mountain Laboratory prions. Two weeks prior infection, the animals were provided with a CHF5074-medicated diet (375 ppm) or a standard diet (vehicle) until they showed neurological signs and eventually died. In intracerebrally infected mice, oral administration of CHF5074 did not prolong survival of the animals. In intraperitoneally-infected mice, CHF5074-treated animals showed a median survival time of 21 days longer than vehicle-treated mice (p < 0.001). In these animals, immunohistochemistry analyses showed that deposition of PrP (Sc) in the cerebellum, hippocampus and parietal cortex in CHF5074-treated mice was significantly lower than in vehicle-treated animals. Immunostaining of glial fibrillary acidic protein (GFAP) in parietal cortex revealed a significantly higher reactive gliosis in CHF5074-treated mice compared to the control group of infected animals. Although the mechanism underlying the beneficial effects of CHF5074 in this murine model of human prion disease is unclear, it could be hypothesized that the drug counteracts PrP (Sc ) toxicity through astrocyte-mediated neuroprotection. CHF5074 shows a pharmacological potential in murine models of both AD and TSEs thus suggesting a link between these degenerative pathologies.

Changes in sympathetic activity in prion neuroinvasion.

Prion diseases are neurodegenerative diseases affecting humans and animals in which the infectious agent or prion is PrP(res), a protease-resistant conformer of the cell protein PrP. The natural transmission route of prion diseases is peripheral infection, with the lymphoreticular system (LRS) and peripheral nerves being involved in animal models of scrapie neuroinvasion and human prion diseases. To study the effects of PrP neuroinvasion on sympathetic nerve function, we measured plasma catecholamine levels, blood pressure, heart rate, and PrP tissue levels in intraperitoneally or intracerebrally infected mice. The results indicate a specific alteration in sympathetic nerve function because the levels of noradrenaline (but not adrenaline) were increased in the animals infected peripherally (but not in those infected intracerebrally) and correlated with increased blood pressure. These findings confirm that prion neuroinvasion uses the sympathetic nervous system to spread from the periphery to the central nervous system after invading the LRS.

Effects of clioquinol on memory impairment and the neurochemical modifications induced by scrapie infection in golden hamsters.

Prion protein (PrP) is a glycoprotein expressed on the surface of neurons and glial cells. Its pathological isoform (PrP(res)) is protease resistant, and involved in the pathogenesis of a number of transmissible encephalopathies (TSEs). One common feature of neurodegenerative diseases, including TSEs, is oxidative stress, which may be responsible not only for the dysfunction or death of neuronal cells, but also cognitive deficits. Clioquinol (5-chloro-7-iodo-8-quinolinol) chelates zinc and copper, which are involved in the deposition of amyloid plaques and acts as an antioxidant; increased lipid peroxidation has also been demonstrated in the early phases of PrP propagation. The aim of this study was to investigate the effects of clioquinol on the changes in motor and cognitive behaviours induced by scrapie infection, as well as its effects on oxidative stress and the neurotransmitters known to be involved in motor and cognitive functions. The results show that clioquinol counteracts the massive memory deficit induced by scrapie infection. This effect is not paralleled by neurochemical changes because the levels of all of the biogenic amines and their metabolites were reduced despite clioquinol treatment. The main biochemical change induced by clioquinol was a marked reduction in lipid peroxidation at all time points. The antioxidant effect of clioquinol can reduce functional impairment and thus improve memory, but clioquinol does not reduce PrP deposition or synapse loss, as indicated by the unchanged Western blot, histopathological and histochemical findings.

Genetic immunization with the immunodominant antigen P48 of Mycoplasma agalactiae stimulates a mixed adaptive immune response in BALBc mice.

A DNA vaccine against contagious agalactia was developed for the first time, encoding the P48 of Mycoplasma agalactiae. Specific immune responses elicited in BALB/c mice were evaluated. Both total IgG and IgG1 were detected in mice vaccinated with pVAX1/P48. Proliferation of mononuclear cells of the spleen, levels of gamma interferon, interleukin-12, and interleukin-2 mRNAs were enhanced in immunized animals. Results indicate that pVAX1/P48 vaccination induced both T(h)1 and T(h)2 immune responses. Nucleic acid immunization could be a new strategy against M. agalactiae infections and may be potentially used to develop vaccines for other Mycoplasma diseases.

Pharmacokinetics and distribution of clioquinol in golden hamsters.

Clioquinol (5-chloro-7-iodo-8-quinolinol) is a zinc and copper chelator that can dissolve amyloid deposits and may be beneficial in Alzheimer's disease. Prion diseases are also degenerative CNS disorders characterised by amyloid deposits. The pharmacokinetics and tissue distribution of drugs active against prions may clarify their targets of action. We describe the pharmacokinetics of clioquinol in hamster plasma, spleen and brain after single and repeated oral or intraperitoneal administration (50 mg kg(-1)), as well as after administration with the diet. A single intraperitoneal administration led to peak plasma clioquinol concentrations after 15 min (Tmax), followed by a decay with an apparent half-life of 2.20 +/- 1.1 h. After oral administration, Tmax was reached after 30 min and was followed by a similar process of decay; the AUC(0-last) was 16% that recorded after intraperitoneal administration. The Cmax and AUC values in spleen after a single administration were about 65% (i.p.) and 25% (p.o.) those observed in blood; those in liver were 35% (p.o.) those observed in blood and those in brain were 20% (i.p.) and 10% (p.o.) those observed in plasma. After repeated oral doses, the plasma, brain and spleen concentrations were similar to those observed at the same times after a single dose. One hour after intraperitoneal dosing, clioquinol was also found in the ventricular CSF. Clioquinol was also given with the diet; its morning and afternoon concentrations were similar, and matched those after oral administration. No toxicity was found after chronic administration. Our results indicate that clioquinol, after oral administration with the diet, reaches concentrations in brain and peripheral tissues (particularly spleen) that can be considered effective in preventing prion accumulation, but are at least ten times lower than those likely to cause toxicity.

Demonstration of coinfection with and recombination by caprine arthritis-encephalitis virus and maedi-visna virus in naturally infected goats.

Recombination of different strains and subtypes is a hallmark of lentivirus infections, particularly for human immunodeficiency virus, and contributes significantly to viral diversity and evolution both within individual hosts and within populations. Recombinant viruses are generated in individuals coinfected or superinfected with more than one lentiviral strain or subtype. This, however, has never been described in vivo for the prototype lentivirus maedi-visna virus of sheep and its closely related caprine counterpart, the caprine arthritis-encephalitis virus. Cross-species infections occur in animals living under natural conditions, which suggests that dual infections with small-ruminant lentiviruses (SRLVs) are possible. In this paper we describe the first documented case of coinfection and viral recombination in two naturally infected goats. DNA fragments encompassing a variable region of the envelope glycoprotein were obtained from these two animals by end-limiting dilution PCR of peripheral blood mononuclear cells or infected cocultures. Genetic analyses, including nucleotide sequencing and heteroduplex mobility assays, showed that these goats harbored two distinct populations of SRLVs. Phylogenetic analysis permitted us to assign these sequences to the maedi-visna virus group (SRLV group A) or the caprine arthritis-encephalitis virus group (SRLV group B). SimPlot analysis showed clear evidence of A/B recombination within the env gene segment of a virus detected in one of the two goats. This case provides conclusive evidence that coinfection by different strains of SRLVs of groups A and B can indeed occur and that these viruses actually recombine in vivo.

Decrease in pathology and progression of scrapie after immunisation with synthetic prion protein peptides in hamsters.

Effective therapy for prion diseases is currently unavailable. Recently, vaccination was shown to be effective in mouse models of a particular neurodegenerative conditions: Alzheimer's disease (AD). Here, we report that vaccination with synthetic oligopeptides homologous to the hamster (Mesocricetus auratus) prion protein augments survival time in animals infected intraperitoneally with 263K scrapie agent. For each hamster included in the study, prion-specific serum antibodies as well as deposition of pathological prion protein (PrP(res)), glial fibrillary acidic protein (GFAP), and mRNA expression for cytokines (TNF alpha, IL-1beta, IL-10) in brain tissues were evaluated. In immunized animals, increased survival after challenge was associated with a reduction of cerebral lesion, PrP deposition and GFAP expression; in these animals, anti-prion protein peptide antibody levels were increased, and the expression of pro-inflammatory cytokines (TNF alpha and IL-1beta) was reduced. Vaccination could be an effective therapeutic approach to postpone disease onset.

Origen y genética del retinoblastoma / Origin and genetics of retinoblastoma

Se estudiaron 51 pacientes afectados de retinoblastoma, de los cuales 30 estaban comprometidos en forma unilateral y los 21 restantes en forma bilateral. De ellos se seleccionaron 5 pedigrees completos de casos hereditarios los que nos sirvieron de base para explicar las dos principales teorías de transmisión genética para esta enfermedad: 1) de Auerbach o Mutación Demorada 2) de Kundson o Multietapas Mutacionales. Completamos con asesoramiento y consejo genético )AU)

Origen y genética del retinoblastoma / Origin and genetics of retinoblastoma

Se estudiaron 51 pacientes afectados de retinoblastoma, de los cuales 30 estaban comprometidos en forma unilateral y los 21 restantes en forma bilateral. De ellos se seleccionaron 5 pedigrees completos de casos hereditarios los que nos sirvieron de base para explicar las dos principales teorías de transmisión genética para esta enfermedad: 1) de Auerbach o Mutación Demorada 2) de Kundson o Multietapas Mutacionales. Completamos con asesoramiento y consejo genético