Insulated π-Conjugated Azido Scaffolds for Stepwise Functionalization via Huisgen Cycloaddition on Metal Oxide Surfaces.

In organic-inorganic hybrid devices, fine interfacial controls by organic components directly affect the device performance. However, fabrication of uniformed interfaces using π-conjugated molecules remains challenging due to facile aggregation by their strong π-π interaction. In this report, a π-conjugated scaffold insulated by covalently linked permethylated α-cyclodextrin moiety with an azido group is synthesized for surface Huisgen cycloaddition on metal oxides. Fourier-transformed infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy confirm the successful immobilization of the insulated azido scaffold on ZnO nanowire array surfaces. Owing to the highly independent immobilization, the scaffold allows rapid and complete conversion of the surface azido group in Huisgen cycloaddition reactions with ethynyl-terminated molecules, as confirmed by FT-IR spectroscopy monitoring. Cyclic voltammetry analysis of modified indium tin oxide substrates shows the positive effects of cyclic insulation toward suppression of intermolecular interaction between molecules introduced by the surface Huisgen cycloaddition reactions. The utility of the scaffold for heterogeneous catalysis is demonstrated in electrocatalytic selective O2 reduction to H2O2 with cobalt(II) chlorin modified fluorine doped tin oxide electrode and photocatalytic H2 generation with iridium(III) dye-sensitized Pt-loaded TiO2 nanoparticle. These results highlight the potential of the insulated azido scaffold for a stepwise functionalization process, enabling precise and well-defined hybrid interfaces.

Calcium-Phosphorus Product Is Associated with Adverse Prognosis in Hospitalized Patients with Heart Failure and Chronic Kidney Disease.

It has been reported that high levels of calcium-phosphorus (Ca-P) product are an indicator of coronary calcification and mortality risk in patients undergoing chronic hemodialysis. In the present study, we aimed to evaluate the significance of Ca-P product to predict the prognosis of patients with heart failure (HF) and chronic kidney disease (CKD). We conducted a prospective observational study of 793 patients with decompensated HF and CKD, and measured the value of Ca-P product. The cut-off value was obtained from the survival classification and regression tree (CART) analysis to predict post-discharge all-cause mortality and/or worsening HF, and the patients were divided into 2 groups: a high group (Ca-P product > 28, n = 594) and a low group (Ca-P product ≤ 28, n = 199). We compared the patient baseline characteristics and post-discharge prognosis between the 2 groups. The age as well as the prevalence of male sex, ischemic etiology, and anemia were significantly higher in the low group than in the high group. In contrast, there was no difference in echocardiographic parameters between the 2 groups. In the Kaplan-Meier analysis (mean follow-up 1089 days), all-cause mortality and/or worsening HF event rates were higher in the low group than in the high group (log-rank P = 0.001). In the multivariable Cox proportional hazard analysis, lower Ca-P product was found to be an independent predictor of all-cause mortality and/or worsening HF (hazard ratio 0.981, P = 0.031). Lower Ca-P product predicts adverse prognosis in patients with HF and CKD.

Predictive Value of Aortic Valve Calcium Volume Measured by Computed Tomography for Paravalvular Leakage After Transcatheter Aortic Valve Implantation.

Paravalvular leakage (PVL) is a complication of transcatheter aortic valve implantation (TAVI) for aortic stenosis, leading to an adverse prognosis. We investigated whether aortic valve calcium volume (Ca-Vol) measured by preoperative cardiac computed tomography had a predictive value for PVL after TAVI using a third-generation self-expandable valve.We retrospectively analyzed 59 consecutive patients who underwent TAVI using a third-generation self-expandable valve. We measured Ca-Vol in the aortic valve and each cusp (non-coronary cusp [NCC], right-coronary cusp [RCC], and left-coronary cusp [LCC]). We divided the patients into 2 groups: a PVL group (32.2%) and a non-PVL group (67.8%). Total Ca-Vol was significantly higher in the PVL group than in the non-PVL group (P < 0.001). Ca-Vol in each cusp was also significantly higher in the PVL group ([NCC] P < 0.001, [RCC] P = 0.001, [LCC] P < 0.001). Univariate logistic regression analysis for PVL indicated that the total and per-cusp Ca-Vols were predictors for PVL (total, odds ratio [OR] 4.0, P < 0.001; NCC, OR 12.5, P = 0.002; RCC, OR 16.0, P = 0.008; LCC, OR 44.5, P < 0.001).Receiver operating characteristic curve analysis of Ca-Vol for predicting PVL revealed the optimal cut-off values of Ca-Vol were 2.4 cm3 for the total, 0.74 cm3 for NCC, 0.73 cm3 for RCC, and 0.56 cm3 for LCC (area under the curve, 0.85, 0.79, 0.76, and 0.83, respectively).Preoperative total, NCC, RCC, and LCC calcium volumes were significant predictors for PVL after TAVI using third-generation self-expandable valves.

Multimodality Risk Assessment of Patients with Ischemic Heart Disease Using Deep Learning Models Applied to Electrocardiograms and Chest X-rays.

Comprehensive management approaches for patients with ischemic heart disease (IHD) are important aids for prognostication and treatment planning. While single-modality deep neural networks (DNNs) have shown promising performance for detecting cardiac abnormalities, the potential benefits of using DNNs for multimodality risk assessment in patients with IHD have not been reported. The purpose of this study was to investigate the effectiveness of multimodality risk assessment in patients with IHD using a DNN that utilizes 12-lead electrocardiograms (ECGs) and chest X-rays (CXRs), with the prediction of major adverse cardiovascular events (MACEs) being of particular concern.DNN models were applied to detection of left ventricular systolic dysfunction (LVSD) on ECGs and identification of cardiomegaly findings on CXRs. A total of 2107 patients who underwent elective percutaneous coronary intervention were categorized into 4 groups according to the models' outputs: Dual-modality high-risk (n = 105), ECG high-risk (n = 181), CXR high-risk (n = 392), and No-risk (n = 1,429).A total of 342 MACEs were observed. The incidence of a MACE was the highest in the Dual-modality high-risk group (P < 0.001). Multivariate Cox hazards analysis for predicting MACE revealed that the Dual-modality high-risk group had a significantly higher risk of MACE than the No-risk group (hazard ratio (HR): 2.370, P < 0.001), the ECG high-risk group (HR: 1.906, P = 0.010), and the CXR high-risk group (HR: 1.624, P = 0.018), after controlling for confounding factors.The results suggest the usefulness of multimodality risk assessment using DNN models applied to 12-lead ECG and CXR data from patients with IHD.

FOUR-WEEK ORAL ADMINISTRATION OF BALOXAVIR MARBOXIL AS AN ANTI-INFLUENZA VIRUS DRUG SHOWS NO TOXICITY IN CHICKENS.

High pathogenicity avian influenza is an acute zoonotic disease with high mortality in birds caused by a high pathogenicity avian influenza virus (HPAIV). Recently, HPAIV has rapidly spread worldwide and has killed many wild birds, including endangered species. Baloxavir marboxil (BXM), an anti-influenza agent used for humans, was reported to reduce mortality and virus secretion from HPAIV-infected chickens (Gallus domesticus, order Galliformes) at a dosage of ≥2.5 mg/kg when administered simultaneously with viral challenge. Application of this treatment to endangered birds requires further information on potential avian-specific toxicity caused by repeated exposure to BXM over the long term. To obtain information of potential avian-specific toxicity, a 4-wk oral repeated-dose study of BXM was conducted in chickens (n = 6 or 7 per group), which are commonly used as laboratory avian species. The study was conducted in reference to the human pharmaceutical guidelines for nonclinical repeated-dose drug toxicity studies to evaluate systemic toxicity and exposure. No adverse changes were observed in any organs examined, and dose proportional increases in systemic exposure to active pharmaceutical ingredients were noted from 12.5 to 62.5 mg/kg per day. BXM showed no toxicity to chickens at doses of up to 62.5 mg/kg per day, at which systemic exposure was approximately 71 times higher than systemic exposure at 2.5 mg/kg, the reported efficacious dosage amount, in HPAIV-infected chickens. These results also suggest that BXM could be considered safe for treating HPAIV-infected endangered birds due to its high safety margin compared with the efficacy dose. The data in this study could contribute to the preservation of endangered birds by using BXM as a means of protecting biodiversity.

Loss of the N-acetylgalactosamine side chain of the GPI-anchor impairs bone formation and brain functions and accelerates the prion disease pathology.

Glycosylphosphatidylinositol (GPI) is a posttranslational glycolipid modification of proteins that anchors proteins in lipid rafts on the cell surface. Although some GPI-anchored proteins (GPI-APs), including the prion protein PrPC, have a glycan side chain composed of N-acetylgalactosamine (GalNAc)-galactose-sialic acid on the core structure of GPI glycolipid, in vivo functions of this GPI-GalNAc side chain are largely unresolved. Here, we investigated the physiological and pathological roles of the GPI-GalNAc side chain in vivo by knocking out its initiation enzyme, PGAP4, in mice. We show that Pgap4 mRNA is highly expressed in the brain, particularly in neurons, and mass spectrometry analysis confirmed the loss of the GalNAc side chain in PrPC GPI in PGAP4-KO mouse brains. Furthermore, PGAP4-KO mice exhibited various phenotypes, including an elevated blood alkaline phosphatase level, impaired bone formation, decreased locomotor activity, and impaired memory, despite normal expression levels and lipid raft association of various GPI-APs. Thus, we conclude that the GPI-GalNAc side chain is required for in vivo functions of GPI-APs in mammals, especially in bone and the brain. Moreover, PGAP4-KO mice were more vulnerable to prion diseases and died earlier after intracerebral inoculation of the pathogenic prion strains than wildtype mice, highlighting the protective roles of the GalNAc side chain against prion diseases.

Efficient Hydrogen Production by a Photoredox Cascade Catalyst Comprising Dual Photosensitizers and a Transparent Electron Mediator.

One-directional electron transport between a photocatalyst and redox mediator is crucial for achieving highly active Z-scheme water-splitting photocatalysis. Herein, a photoredox cascade catalyst that artificially mimics the electron transport chain in natural photosynthesis was synthesized from a Pt-TiO2 nanoparticle catalyst, two photosensitizers (RuCP6 and RuP6), and a visible-light-transparent electron mediator (HCRu). During photocatalytic hydrogen evolution in the presence of a redox-reversible electron donor, [Co(bpy)3]2+ (bpy = 2,2'-bipyridine), the HCRu-Zr-RuCP6-Zr-RuP6@Pt-TiO2 (PRCC-1) photocatalyst exhibited the highest reported initial (1 h) apparent quantum yield (iAQY = 2.23%) of dye-sensitized TiO2 photocatalysts to date. Furthermore, PRCC-1 successfully produced hydrogen when using hydroquinone monosulfonate (H2QS-) as the hydrogen source.

A point mutation in GPI-attachment signal peptide accelerates the development of prion disease.

A missense variant from methionine to arginine at codon 232 (M232R) of the prion protein gene accounts for ~ 15% of Japanese patients with genetic prion diseases. However, pathogenic roles of the M232R substitution for the induction of prion disease have remained elusive because family history is usually absent in patients with M232R. In addition, the clinicopathologic phenotypes of patients with M232R are indistinguishable from those of sporadic Creutzfeldt-Jakob disease patients. Furthermore, the M232R substitution is located in the glycosylphosphatidylinositol (GPI)-attachment signal peptide that is cleaved off during the maturation of prion proteins. Therefore, there has been an argument that the M232R substitution might be an uncommon polymorphism rather than a pathogenic mutation. To unveil the role of the M232R substitution in the GPI-attachment signal peptide of prion protein in the pathogenesis of prion disease, here we generated a mouse model expressing human prion proteins with M232R and investigated the susceptibility to prion disease. The M232R substitution accelerates the development of prion disease in a prion strain-dependent manner, without affecting prion strain-specific histopathologic and biochemical features. The M232R substitution did not alter the attachment of GPI nor GPI-attachment site. Instead, the substitution altered endoplasmic reticulum translocation pathway of prion proteins by reducing the hydrophobicity of the GPI-attachment signal peptide, resulting in the reduction of N-linked glycosylation and GPI glycosylation of prion proteins. To the best of our knowledge, this is the first time to show a direct relationship between a point mutation in the GPI-attachment signal peptide and the development of disease.

Vapor-Induced Assembly of a Platinum(II) Complex Loaded on Layered Double Hydroxide Nanoparticles.

Controlled self-assembly of PtII complexes is key to the development of optical and stimuli-responsive materials, but designing and precisely controlling them is still difficult owing to weak intermolecular interactions. Herein, we report the successful water-vapor-induced assembly of an anionic PtII complex [Pt(CN)2 (ppy)]- (Hppy=2-phenylpyridine) electrostatically loaded onto cationically charged layered double hydroxide (LDH) nanoparticles consisting of Mg2+ and Al3+ ions. When the PtII complexes were densely loaded onto the LDH nanoparticles, the assembly was maintained, even in dilute aqueous media. In the case of sparse loading, the PtII complexes were loaded discretely in the dry state; however, when water vapor was adsorbed, the increased mobility of the PtII complexes led to their assembly on the LDH nanoparticles. The presence of water vapor led to a drastic change in luminescence from green to orange.

Vapor-Induced Assembly of a Platinum(II) Complex Loaded on Layered Double Hydroxide Nanoparticles.

Invited for the cover of this issue is the group of Masaki Yoshida and Masako Kato at Hokkaido University/Kwansei Gakuin University. The image depicts the changes in the assembly of PtII complexes with humidity on layered double hydroxide (LDH) nanoparticles, resulting in a drastic emission color change from green to orange. Read the full text of the article at 10.1002/chem.202301993.

Evaluation of the host specificity of Eimeria uekii and Eimeria raichoi for Japanese rock ptarmigans by oocyst transfer to taxonomically related birds.

Eimeria spp. are protozoan parasites that are commonly found in a broad range of vertebrate hosts. These parasites generally exhibit strict host specificity, but some Eimeria spp. can infect groups of closely related species such as species within a genus or family. Compared with Eimeria spp. that infect livestock, limited information is available about such infections in wild animals including data on host specificity, virulence, and prevalence. The Japanese rock ptarmigan, Lagopus muta japonica, is an endangered bird belonging to the family Phasianidae, order Galliformes, and inhabits only alpine areas of Japan. In conservation efforts for these birds, two Eimeria spp., E. uekii and E. raichoi, were frequently detected. Here, we examined cross-transmission of the parasites to other bird species to characterize their infectivity as well as the development of experimental bird models to contribute to conservation programs by the oocyst transfer. Consequently, among the examined eight bird species (chickens, Japanese pheasants, turkeys, chukar partridges, quails, helmeted guineafowls and ducks), only turkeys (family Phasianidae, order Galliformes) could be infected with E. raichoi. However, the number of oocysts per feces was relatively low, and few parasites in the intestinal mucosa could be found by histopathological analyses. These results might indicate that E. uekii and E. raichoi are highly adapted to Japanese rock ptarmigans that inhabit the alpine zone although further studies are anticipated.

Photoredox Cascade Catalyst for Efficient Hydrogen Production with Biomass Photoreforming.

Biomass photoreforming is a promising method to provide both a clean energy resource in the form of hydrogen (H2 ) and valuable chemicals as the results of water reduction and biomass oxidation. To overcome the poor contact between heterogeneous photocatalysts and biomass substrates, we fabricated a new photoredox cascade catalyst by combining a homogeneous catalyst, 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO), and a heterogeneous dual-dye sensitized photocatalyst (DDSP) composed of two Ru(II)-polypyridine photosensitizers (RuP6 and RuCP6 ) and Pt-loaded TiO2 nanoparticles. During blue-light irradiation (λ=460±15 nm; 80 mW), the DDSP photocatalytically reduced aqueous protons to form H2 and simultaneously oxidized TEMPO• radicals to generate catalytically active TEMPO+ . It oxidized biomass substrates (water-soluble glycerol and insoluble cellulose) to regenerate TEMPO• . In the presence of N-methyl imidazole as a proton transfer mediator, the photocatalytic H2 production activities for glycerol and cellulose reforming reached 2670 and 1590 µmol H2 (gTiO2 )-1  h-1 , respectively, which were comparable to those of state-of-the-art heterogeneous photocatalysts.

Effect of dopamine receptor-related compounds on naïve common marmosets for auditory steady-state response.

Abnormalities of auditory steady-state responses (ASSRs) and the effects of antipsychotic drugs on ASSRs have been investigated in patients with schizophrenia. It is presumed that drugs do not directly affect ASSRs because its abnormalities are associated with schizophrenia. Therefore, to investigate the direct effect of drugs on ASSRs, we established an ASSR evaluation system for common marmosets in a naïve state. Dopamine D1 receptor stimulation (SKF-81297, 2 mg/kg ip) significantly increased evoked power (EP) at 40 Hz. The phase locking factor (PLF) was increased significantly at 20, 30, 40, and 80 Hz. However, administration of a dopamine D1 receptor antagonist (SCH-39166, 0.3 mg/kg ip) resulted in a significant decrease in EP and PLF at 30 Hz. Dopamine D2 receptor stimulation (quinpirole, 1 mg/kg im) tended to increase EP and induced power (IP) at all frequencies, and a significant difference was observed at 30 Hz IP. There was no change in PLF at all frequencies. In addition, dopamine D2 receptor blockade (raclopride, 3 mg/kg ip) reduced EP and PLF at 30 Hz. Subcutaneous administration of the serotonin dopamine antagonist, risperidone (0.3 mg/kg), tended to increase IP and decrease PLF, but not significantly. Taken together, it is possible to compare the differences in the mode of action of drugs on ASSRs using naïve nonhuman primates.NEW & NOTEWORTHY We measured the effects of dopamine receptor-related compounds on ASSR in marmosets. D1 receptor stimulation increased the phase locking factor (PLF) and evoked power (EP), and reduced the induced power (IP). D2 receptor stimulation increased the IP. D1 and D2 receptor blockers reduced the PLF and EP at 30 Hz. Different modes of action of various drugs related to psychiatric disorders were evaluated by administering antipsychotic drugs to naïve marmosets.

Reversible and Stepwise Single-Crystal-to-Single-Crystal Transformation of a Platinum(II) Complex with Vapochromic Luminescence.

The vapochromic single-crystal-to-single-crystal (SCSC) transformation of a highly luminescent PtII complex bearing an N-heterocyclic carbene [Pt(CN)2 (tBu-impy)] (tBu-impyH+ =1-tert-butyl-3-(2-pyridyl)-1H-imidazolium) is reported. The trihydrate form of the complex, which exhibits blue 3 MMLCT emission owing to weak Pt⋅⋅⋅Pt interactions, changed its luminescence color from blue to yellowish-green upon the desorption of water molecules while keeping the high emission quantum yield of more than 0.45. Variable-temperature and continuous in-situ tracking of single-crystal X-ray diffraction measurements revealed that the SCSC transformation proceeds reversibly by the release and reabsorption of water molecules, thereby changing the stacked structure slightly. As a result, the dynamics of vapor-induced SCSC transformation were elucidated: that the anhydrous form returned to the original trihydrate form in a two-step process under a water vapor atmosphere. In addition, the PtII complex exhibited a similar SCSC response accompanied by a luminescence color change in the presence of methanol vapor, while being inactive toward ethanol vapor.

Photocatalyst-Mediator Interface Modification by Surface-Metal Cations of a Dye-Sensitized H2 Evolution Photocatalyst.

To develop highly active H2 evolving dye-sensitized photocatalysts (DSPs) applicable for Z-scheme water splitting, we synthesized a series of Ru(II)-dye-double-layered DSPs, X'-RuCP6-Zr-RuP6@Pt-TiO2 (X'-DSP) with different surface-bound metal cations (X' = Fe2+, Y3+, Zr4+, Hf4+, and Bi3+). In 0.5 M KI aqueous solution, the photocatalytic H2 evolution activity under blue light irradiation (λ = 460 ± 15 nm) increased in the following order: nonmetal-modified DSP, H+-DSP (turn over number for 6 h irradiation = 35.2) < Fe2+-DSP (54.9) ≈ Bi3+-DSP (55.2) < Hf4+-DSP (65.5) ≈ Zr4+-DSP (68.3) ≈ Y3+-DSP (71.5), suggesting that the redox-inactive and highly charged metal cations tend to improve the electron donation from the iodide electron mediator. On the other hand, DSPs having heavy metal cations, Hf4+-DSP (18.4) and Bi3+-DSP (16.6), exhibited better activity under green light irradiation (λ = 530 ± 15 nm) than Zr4+-DSP (15.7) and H+-DSP (7.80), implying the contribution of a heavy atom effect of the surface-bound metal cation to partially allow the spin-forbidden metal-to-ligand charge-transfer excitation.

Prognostic Effects of Changes in Right Ventricular Fractional Area Change in Patients With Heart Failure.

BACKGROUND: It is still unclear whether changes in right ventricular function are associated with prognosis in heart failure (HF) patients. This study aimed to examine the prognostic effect of changes in right ventricular fractional area change (RVFAC).Methods and Results: This study enrolled 480 hospitalized patients with decompensated HF, and measured RVFAC with echocardiography at discharge (first examination) and post-discharge in the outpatient setting (second examination). RVFAC was divided into 3 categories: >35% in 314 patients, 25-35% in 108 patients, and <25% in 58 patients. Next, based on changes in RVFAC from the first to the second examination, the patients were further classed into 4 groups: (1) Preserved/Unchanged (preserved and unchanged RVFAC, n=235); (2) Reduced/Improved (improved RVFAC in at least 1 category, n=106); (3) Reduced/Unchanged (reduced and unchanged RVFAC, n=47); and (4) Preserved or Reduced/Worsened (deteriorated RVAFC in at least 1 category, n=92). Multivariate logistic regression analysis revealed that chronic kidney disease and anemia were the predictors of the preserved or reduced/worsened RVFAC. In the Kaplan-Meier analysis, changes in RVFAC were associated with the cardiac event rate and all-cause mortality. In the multivariable Cox proportional hazard analysis, the preserved or reduced/worsened RVFAC was an independent predictor of cardiac events and all-cause mortality. CONCLUSIONS: Changes in RVFAC were associated with post-discharge prognosis in hospitalized heart failure patients.

Morphological plasticity in response to salinity change in the euryhaline diatom Pleurosira laevis (Bacillariophyta).

Pleurosira laevis is a salt-tolerant diatom distributed around the world. The valve of P. laevis has distinct structures called ocelli, which are sharply defined areas with fine, densely packed pores. Two formae of this diatom, P. laevis f. laevis and P. laevis f. polymorpha, are distinguished from each other by their flat or dome-shaped valve faces and degree of elevation of the ocelli, respectively. In this study, we established 4 strains of P. laevis isolated from freshwaters or coastal areas in Japan and the United States, and tracked the formation of newly formed valves with the fluorescent SDV-specific dye PDMPO in culture under several salinity conditions. The result clearly demonstrated the morphological plasticity of the valves, controlled by environmental salinity. The laevis form and polymorpha form valves were produced at salinities of 2 and 7, respectively. The salinity thresholds dictating the morphological plasticity of the valve were consistent in all 4 strains. A similar morphology to the polymorpha form was reproduced in a freshwater medium with the addition of sorbitol, suggesting that osmotic pressure plays a key role in this morphological plasticity. The highly reproducible and easily manipulated change in morphology makes this diatom an ideal model for lab experiments focusing on the molecular and genetic factors involved with valve morphogenesis.

Synthesis and cytotoxic activities of 8- and 6-demethyleucalyptins.

Secondary metabolites in plants influence the health of herbivores such as Japanese rock ptarmigans that feed on the leaves and fruits of alpine plants. Thus, it is important to understand the secondary metabolites of alpine plants and their biological activities for conserving Japanese rock ptarmigans. We isolated C-methylflavone from the leaves of Kalmia procumbens, on which Japanese rock ptarmigans feed. Although its structure was deduced to be 8-demethyleucalyptin by comparing its nuclear magnetic resonance (NMR) data with the reported ones, the possibility that the isolated compound is 6-demethyleucalyptin cannot be ruled out. Thus, both isomers were synthesized. The isolated compound was unambiguously determined to be 8-demethyleucalyptin by comparing its NMR data with those of the synthetic ones. Cytotoxic evaluation of 8- and 6-demethyleucalyptins revealed that only the former showed cytotoxicity against HCT116 and MRC-5 cells. The present study provides not only easy access to 8- and 6-demethyleucalyptins, but also their biological information.

α2,3 linkage of sialic acid to a GPI anchor and an unpredicted GPI attachment site in human prion protein.

Prion diseases are transmissible, lethal neurodegenerative disorders caused by accumulation of the aggregated scrapie form of the prion protein (PrPSc) after conversion of the cellular prion protein (PrPC). The glycosylphosphatidylinositol (GPI) anchor of PrPC is involved in prion disease pathogenesis, and especially sialic acid in a GPI side chain reportedly affects PrPC conversion. Thus, it is important to define the location and structure of the GPI anchor in human PrPC Moreover, the sialic acid linkage type in the GPI side chain has not been determined for any GPI-anchored protein. Here we report GPI glycan structures of human PrPC isolated from human brains and from brains of a knock-in mouse model in which the mouse prion protein (Prnp) gene was replaced with the human PRNP gene. LC-electrospray ionization-MS analysis of human PrPC from both biological sources indicated that Gly229 is the ω site in PrPC to which GPI is attached. Gly229 in human PrPC does not correspond to Ser231, the previously reported ω site of Syrian hamster PrPC We found that ∼41% and 28% of GPI anchors in human PrPCs from human and knock-in mouse brains, respectively, have N-acetylneuraminic acid in the side chain. Using a sialic acid linkage-specific alkylamidation method to discriminate α2,3 linkage from α2,6 linkage, we found that N-acetylneuraminic acid in PrPC's GPI side chain is linked to galactose through an α2,3 linkage. In summary, we report the GPI glycan structure of human PrPC, including the ω-site amino acid for GPI attachment and the sialic acid linkage type.

Potential for transmission of sporadic Creutzfeldt-Jakob disease through peripheral routes.

Five sporadic Creutzfeldt-Jakob disease (CJD) strains have been identified to date, based on differences in clinicopathological features of the patients, the biochemical properties of abnormal prion proteins, and transmission properties. Recent advances in our knowledge about iatrogenic transmission of sporadic CJD have raised the possibility that the infectivity of sporadic CJD strains through peripheral routes is different from that of intracranial infection. To test this possibility, here we assessed systematically the infectivity of sporadic CJD strains through the peripheral route for the first time using a mouse model expressing human prion protein. Although the infectivity of the V2 and M1 sporadic CJD strains is almost the same in intracerebral transmission studies, the V2 strain infected more efficiently than the M1 strain through the peripheral route. The other sporadic CJD strains examined lacked infectivity. Of note, both the V2 and M1 strains showed preference for mice with the valine homozygosity at the PRNP polymorphic codon. These results indicate that the V2 strain is the most infectious sporadic CJD strain for infection through peripheral routes. In addition, these findings raise the possibility that individuals with the valine homozygosity at the PRNP polymorphic codon might have higher risks of infection through peripheral routes compared with the methionine homozygotes. Thus, preventive measures against the transmission of the V2 sporadic CJD strain will be important for the eradication of iatrogenic CJD transmission through peripheral routes.