We established that follicular dendritic cells (FDCs) are the site of abnormal prion protein (PrPCJD) accumulations in lymphoid tissues from mice infected with Creutzfeldt-Jakob disease. Evidence of positive FDC staining was observed in Creutzfeldt-Jakob disease-infected mice irrespective of the inoculation route, while no such staining was seen in the control mice. We also found that the severe combined immunodeficiency mouse trait is transmittable via the intracranial route but not via the intraperitoneal route. Mice with severe combined immunodeficiency did not have PrPCJD accumulation in FDCs.

The therapeutic efficacy of direct drug infusion into the brain, the target organ of transmissible spongiform encephalopathies, was assessed in transgenic mice intracerebrally infected with 263K scrapie agent. Pentosan polysulfate (PPS) gave the most dramatic prolongation of the incubation period, and amphotericin B had intermediate effects, but antimalarial drugs such as quinacrine gave no significant prolongation. Treatment with the highest dose of PPS at an early or late stage of the infection prolonged the incubation time by 2.4 or 1.7 times that of the control mice, respectively. PPS infusion decreased not only abnormal prion protein deposition but also neurodegenerative changes and infectivity. These alterations were observed within the brain hemisphere fitted with an intraventricular infusion cannula but not within the contralateral hemisphere, even at the terminal disease stage long after the infusion had ended. Therapeutic effects of PPS were also demonstrated in mice infected with either RML agent or Fukuoka-1 agent. However, at doses higher than that providing the maximal effects, intraventricular PPS infusion caused adverse effects such as hematoma formation in the experimental animals. These findings indicate that intraventricular PPS infusion might be useful for the treatment of transmissible spongiform encephalopathies in humans, providing that the therapeutic dosage is carefully evaluated.

Ca2+ handling in excitation-contraction coupling requires considerable O2 consumption (Vo 2) in cardiac contraction. We have developed an integrative method to quantify total Ca2+ handling in normal hearts. However, its direct application to failing hearts, where futile Ca2+ cycling via the Ca2+-leaky sarcoplasmic reticulum (SR) required an increased Ca2+handling Vo 2, was not legitimate. To quantify total Ca2+ handling even in such failing hearts, we combined futile Ca2+ cycling with Ca2+ handling Vo 2 and the internal Ca2+ recirculation fraction via the SR. We applied this method to the canine heart mechanoenergetics before and after intracoronary ryanodine at nanomolar concentrations. We found that total Ca2+ handling per beat was halved after the ryanodine treatment from ∼60 μmol/kg left ventricle before ryanodine. We also found that futile Ca2+ cycling via the SR increased to >1 cycle/beat after ryanodine from presumably zero before ryanodine. These results support the applicability of the present method to the failing hearts with futile Ca2+ cycling via the SR.

Transfer RNAs (tRNAs) contain a wide variety of posttranscriptional modifications that are important for accurate decoding. Mammalian mitochondrial tRNAs (mt-tRNAs) are modified by nuclear-encoded tRNA-modifying enzymes; however, the physiological roles of these modifications remain largely unknown. In this study, we report that Cdk5 regulatory subunit-associated protein 1 (Cdk5rap1) is responsible for 2-methylthio (ms(2)) modifications of mammalian mt-tRNAs for Ser(UCN), Phe, Tyr, and Trp codons. Deficiency in ms(2) modification markedly impaired mitochondrial protein synthesis, which resulted in respiratory defects in Cdk5rap1 knockout (KO) mice. The KO mice were highly susceptive to stress-induced mitochondrial remodeling and exhibited accelerated myopathy and cardiac dysfunction under stressed conditions. Furthermore, we demonstrate that the ms(2) modifications of mt-tRNAs were sensitive to oxidative stress and were reduced in patients with mitochondrial disease. These findings highlight the fundamental role of ms(2) modifications of mt-tRNAs in mitochondrial protein synthesis and their pathological consequences in mitochondrial disease.

) (21 and 19 kDa, respectively), reflecting differences in the proteinase K cleavage site (at residues 82 and 97, respectively) (2, 3). The genotype at codon 129 also influences the susceptibility to variant CJD (vCJD), iatrogenic CJD, and kuru (6 -11). A transmission study using transgenic mice expressing human PrP revealed that the congruency of the genotype at codon 129 between the inoculum and the inoculated transgenic mice determines the susceptibility to sCJD prions (12). Transmission of sCJD prions to mice with an incongruent genotype (referred to as cross-sequence transmission) results in a relatively long incubation period.The potential for cross-sequence transmission should be considered in the iatrogenic transmission of CJD via cadaveric pituitary hormones, dura mater and corneal grafts, or contaminated neurosurgical instruments. More than half of the reported cases of dura mater graft-associated CJD (dCJD) occurred in Japan, where 123 cases have been recognized as of February 2006 (13-16). The dural grafts used in Japan were manufactured by German companies (13-15). In Europe, 28.4% of sCJD patients are valine homozygotes (129V/V) or methionine/valine heterozygotes at codon 129 (129M/V) (5). Meanwhile, the population data show a high prevalence (91.6%) of methionine homozygosity (129M/M) in Japanese people (17). These data raise the possibility that part of the Japanese dCJD cases might have been caused by cross-sequence transmission of sCJD prions. In fact, there are two distinct phenotypes in dCJD, with the majority represented by a non-plaque type of dCJD (np-dCJD) and the minority by a plaque-type dCJD (p-dCJD) (18 -21). The clinicopathological features of np-dCJD are similar to those of sCJD with 129M/M and type 1 PrP Sc (sCJD-MM1) (14). In contrast, p-dCJD cases show unique features characterized by (i) the absence or late occurrence of myoclonus and periodic synchronous discharges on electroencephalogram; (ii) a long incubation period after grafting and a clinical course of long duration, and (iii) plaque-type PrP deposits in the brain (18 -25). Although we have classified p-dCJD cases into MM1, the clinicopathological features of p-dCJD are quite different from those of sCJD-MM1 or npdCJD (18 -21). The reason for the existence of two distinct phenotypes in dCJD has remained elusive.To identify the origin of p-dCJD, we inoculated sCJD prions into mice expressing human PrP with either 129M/M or 129V/V. Here we report that cross-sequence transmission of sCJD prions from a patient with 129V/V and type 2 PrP Sc