The Physical Relationship between Infectivity and Prion Protein Aggregates Is Strain-Dependent

Prions are unconventional infectious agents thought to be primarily composed of PrPSc, a multimeric misfolded conformer of the ubiquitously expressed host-encoded prion protein (PrPC). They cause fatal neurodegenerative diseases in both animals and humans. The disease phenotype is not uniform within species, and stable, self-propagating variations in PrPSc conformation could encode this ‘strain’ diversity. However, much remains to be learned about the physical relationship between the infectious agent and PrPSc aggregation state, and how this varies according to the strain. We applied a sedimentation velocity technique to a panel of natural, biologically cloned strains obtained by propagation of classical and atypical sheep scrapie and BSE infectious sources in transgenic mice expressing ovine PrP. Detergent-solubilized, infected brain homogenates were used as starting material. Solubilization conditions were optimized to separate PrPSc aggregates from PrPC. The distribution of PrPSc and infectivity in the gradient was determined by immunoblotting and mouse bioassay, respectively. As a general feature, a major proteinase K-resistant PrPSc peak was observed in the middle part of the gradient. This population approximately corresponds to multimers of 12–30 PrP molecules, if constituted of PrP only. For two strains, infectivity peaked in a markedly different region of the gradient. This most infectious component sedimented very slowly, suggesting small size oligomers and/or low density PrPSc aggregates. Extending this study to hamster prions passaged in hamster PrP transgenic mice revealed that the highly infectious, slowly sedimenting particles could be a feature of strains able to induce a rapidly lethal disease. Our findings suggest that prion infectious particles are subjected to marked strain-dependent variations, which in turn could influence the strain biological phenotype, in particular the replication dynamics

Correction: International Society of Sports Nutrition position stand: Nutrient timing

Position Statement: The position of the Society regarding nutrient timing and the intake of carbohydrates, proteins, and fats in reference to healthy, exercising individuals is summarized by the following eight points: 1.) Maximal endogenous glycogen stores are best promoted by following a high-glycemic, high-carbohydrate (CHO) diet (600 – 1000 grams CHO or ~8 – 10 g CHO/kg/d), and ingestion of free amino acids and protein (PRO) alone or in combination with CHO before resistance exercise can maximally stimulate protein synthesis. 2.) During exercise, CHO should be consumed at a rate of 30 – 60 grams of CHO/hour in a 6 – 8% CHO solution (8 – 16 fluid ounces) every 10 – 15 minutes. Adding PRO to create a CHO:PRO ratio of 3 – 4:1 may increase endurance performance and maximally promotes glycogen re-synthesis during acute and subsequent bouts of endurance exercise. 3.) Ingesting CHO alone or in combination with PRO during resistance exercise increases muscle glycogen, offsets muscle damage, and facilitates greater training adaptations after either acute or prolonged periods of supplementation with resistance training. 4.) Post-exercise (within 30 minutes) consumption of CHO at high dosages (8 – 10 g CHO/kg/day) have been shown to stimulate muscle glycogen re-synthesis, while adding PRO (0.2 g – 0.5 g PRO/kg/day) to CHO at a ratio of 3 – 4:1 (CHO: PRO) may further enhance glycogen re-synthesis. 5.) Post-exercise ingestion (immediately to 3 h post) of amino acids, primarily essential amino acids, has been shown to stimulate robust increases in muscle protein synthesis, while the addition of CHO may stimulate even greater levels of protein synthesis. Additionally, pre-exercise consumption of a CHO + PRO supplement may result in peak levels of protein synthesis. 6.) During consistent, prolonged resistance training, post-exercise consumption of varying doses of CHO + PRO supplements in varying dosages have been shown to stimulate improvements in strength and body composition when compared to control or placebo conditions. 7.) The addition of creatine (Cr) (0.1 g Cr/kg/day) to a CHO + PRO supplement may facilitate even greater adaptations to resistance training. 8.) Nutrient timing incorporates the use of methodical planning and eating of whole foods, nutrients extracted from food, and other sources. The timing of the energy intake and the ratio of certain ingested macronutrients are likely the attributes which allow for enhanced recovery and tissue repair following high-volume exercise, augmented muscle protein synthesis, and improved mood states when compared with unplanned or traditional strategies of nutrient intake

Enzymatic formulation capable of degrading scrapie prion under mild digestion conditions

The prion agent is notoriously resistant to common proteases and conventional sterilisation procedures. The current methods known to destroy prion infectivity such as incineration, alkaline and thermal hydrolysis are harsh, destructive, environmentally polluting and potentially hazardous, thus limit their applications for decontamination of delicate medical and laboratory devices, remediation of prion contaminated environment and for processing animal by-products including specified risk materials and carcases. Therefore, an environmentally friendly, non-destructive enzymatic degradation approach is highly desirable. A feather-degrading Bacillus licheniformis N22 keratinase has been isolated which degraded scrapie prion to undetectable level of PrPSc signals as determined by Western Blot analysis. Prion infectivity was verified by ex vivo cell-based assay. An enzymatic formulation combining N22 keratinase and biosurfactant derived from Pseudomonas aeruginosa degraded PrPSc at 65°C in 10 min to undetectable level -. A time-course degradation analysis carried out at 50°C over 2 h revealed the progressive attenuation of PrPSc intensity. Test of residual infectivity by standard cell culture assay confirmed that the enzymatic formulation reduced PrPSc infectivity to undetectable levels as compared to cells challenged with untreated standard scrapie sheep prion (SSBP/1) (p-value = 0.008 at 95% confidence interval). This novel enzymatic formulation has significant potential application for prion decontamination in various environmentally friendly systems under mild treatment conditions

HIGH-MOLECULAR-WEIGHT HYDROXYPROPYLMETHYLCELLULOSE - A CHOLESTEROL-LOWERING AGENT

Background: We assessed the efficacy of a high-molecular-weight hydroxypropylmethylcellulose (K8515) as a cholesterol-lowering agent, the dose-response profile of its action, and the ability of adult subjects to tolerate its ingestion at effective doses. Methods: These studies were conducted at the Clinical Research Center of The University of Michigan Hospitals, Ann Arbor. Efficacy was assessed in 10 normal and 12 mildly hyperlipidemic subjects in double-blind, randomized crossover trials of 1 and 2 weeks’ duration, respectively. The dose-response profile was studied in 12 mildly hypercholesterolemic subjects in a nonrandomized control trial with doses given in escalating order. Tolerance was assessed by a questionnaire of adverse effects and bowel movement habits in all subjects. Results: We found that 10 g of K8515 ingested in a prehydrated form three times a day with meals lowered total cholesterol levels by an average of 1.45 mmol/L (56 mg/dL) (32%) in normal subjects within 1 week. In two studies in subjects with mildly elevated cholesterol levels (with entry levels ranging from 5.35 mmol/L [207 mg/dL] to 6.70 nunol/L [260 mg/dL]), average reductions of 1.00 mmol/L (39 mg/dL) (18%) and 1.15 mmol/L (45 mg/dL) (20%) were observed within the same period. The effect was primarily due to a reduction in low-density lipoprotein cholesterol levels. Low-density lipoprotein levels in normal subjects were an average of 1.10 mmol/L (42 mg/dL) (38%) lower after a week of 10 g of K8515 three times a day with meals, and in the two studies in subjects with mild hyperlipidemia, the reductions in low-density lipoprotein levels after 1 week were 0.95 mmol/L (37 mg/dL) (23%) and 1.05 mmol/L (40 mg/dL) (25%). Although there was a tendency for high-density lipoprotein cholesterol levels to decrease, this was significant only in normal subjects. Decreases in cholesterol levels were not accompanied by any rise in triglyceride levels. Dose-response studies in those with mildly elevated cholesterol levels indicated that it is possible to achieve a 15% decrease in low-density lipoprotein cholesterol levels within 1 week at a dose of 6.7 g three times a day, with minimal adverse effects. Conclusions: These results suggest a role for high-molecular-weight hydroxypropylmethylcellulose in the clinical treatment of mild hypercholesterolemia

Afterword : Zhibo, existential territory, inter-media-mundia

In undertaking transversal research into the problems of contemporary Japanese urban life, we shall critically examine the production of subjectivities pertaining to live streaming. This is undertaken to conceptualize the changing nature of subjectivity and social relations in contemporary transnational and transcultural capitalism. We shall look to Félix Guattari’s semiotic theory to interpret the era of Integrated World Capitalism (IWC). For Guattari, the production of subjectivity is pivotal to explaining the functioning of contemporary capitalism. As he claimed in his lifetime, subjectivity has become the number one objective of contemporary, capitalist society. Contra the trend to exploit subjectivity for monetary gain, Guattari’s goal is to identify mutant nuclei of subjectification which may engender a change in the order of things. His work is applied to new communication technologies like live streaming (Zhibo) to account for the existential breakdowns and breakthroughs which may ensue for individuals who use these technologies. Bradley has designated this as the Zerrissenheit or torn-to-pieces-hood of subjectivity (Bradley in Tamkang Review, 44(2): 37– 62, 2014)

Stem cell repopulation efficiency but not pool size is governed by p27kip1

Sustained blood cell production requires preservation of a quiescent, multipotential stem cell pool that intermittently gives rise to progenitors with robust proliferative potential. The ability of cells to shift from a highly constrained to a vigorously active proliferative state is critical for maintaining stem cells while providing the responsiveness necessary for host defense. The cyclin-dependent kinase inhibitor (CDKI), p21cip1/waf1 (p21) dominates stem cell kinetics. Here we report that another CDKI, p27kip1 (p27), does not affect stem cell number, cell cycling, or self-renewal, but markedly alters progenitor proliferation and pool size. Therefore, distinct CDKIs govern the highly divergent stem and progenitor cell populations. When competitively transplanted, p27-deficient stem cells generate progenitors that eventually dominate blood cell production. Modulating p27 expression in a small number of stem cells may translate into effects on the majority of mature cells, thereby providing a strategy for potentiating the impact of transduced cells in stem cell gene therapy