Mitochondria are critical to cellular and organismal health. To prevent damage, mitochondria have evolved protein quality control machines to survey and maintain the mitochondrial proteome. SKD3, ...also known as CLPB, is a ring-forming, ATP-fueled protein disaggregase essential for preserving mitochondrial integrity and structure. SKD3 deficiency causes 3-methylglutaconic aciduria type VII (MGCA7) and early death in infants, while mutations in the ATPase domain impair protein disaggregation with the observed loss-of-function correlating with disease severity. How mutations in the non-catalytic N-domain cause disease is unknown. Here, we show that the disease-associated N-domain mutation, Y272C, forms an intramolecular disulfide bond with Cys267 and severely impairs SKD3
function under oxidizing conditions and in living cells. While Cys267 and Tyr272 are found in all SKD3 isoforms, isoform-1 features an additional α-helix that may compete with substrate-binding as suggested by crystal structure analyses and in silico modeling, underscoring the importance of the N-domain to SKD3 function.
Summary
Background
Control of equine infectious anaemia (EIA) currently depends on serological diagnosis of infected equids. However, recently infected equids may not produce detectable anti‐EIAV ...antibodies up to 157 days post infection and so present a high transmission risk. Therefore, direct nucleic acid detection methods are urgently needed to improve EIAV surveillance and management programs in counties where the disease is endemic.
Objectives
To evaluate a field‐deployable, reverse transcription‐insulated isothermal PCR (RT‐iiPCR) assay targeting the conserved 5′ untranslated region (5′ UTR)/exon 1 of the tat gene of EIAV.
Study design
The analytical and clinical performance of the newly developed EIAV RT‐iiPCR was evaluated by comparison with a EIAV real‐time RT‐PCR (RT‐qPCR) along with the AGID test.
Methods
Analytical sensitivity was determined using in vitro transcribed RNA containing the target area of the 5′ UTR/tat gene and samples from two EIAV‐positive horses. Specificity was verified using nine common equine viruses. Clinical performance was evaluated by comparison with EIAV RT‐qPCR and AGID using samples derived from 196 inapparent EIAV carrier horses.
Results
EIAV RT‐iiPCR did not react with other commonly encountered equine viruses and had equivalent sensitivity (95% detection limit of eight genome equivalents), with a concordance of 95.41% to conventional EIAV RT‐qPCR. However, the RT‐qPCR and RT‐iiPCR had sensitivities of 43.75 and 50.00%, respectively, when compared to the AGID test.
Main limitations
Low viral loads commonly encountered in inapparent EIAV carriers may limit the diagnostic sensitivity of RT‐PCR‐based tests.
Conclusions
Although EIAV RT‐iiPCR is not sufficiently sensitive to replace the current AGID test, it can augment control efforts by identifying recently exposed or “serologically silent” equids, particularly as the latter often represent a significant transmission risk because of high viral loads. Furthermore, the relatively low cost and field‐deployable design enable utilisation of EIAV RT‐iiPCR even in remote regions.
A functional association is uncovered between the ribosome-associated trigger factor (TF) chaperone and the ClpXP degradation complex. Bioinformatic analyses demonstrate conservation of the close ...proximity of tig, the gene coding for TF, and genes coding for ClpXP, suggesting a functional interaction. The effect of TF on ClpXP-dependent degradation varies based on the nature of substrate. While degradation of some substrates are slowed down or are unaffected by TF, surprisingly, TF increases the degradation rate of a third class of substrates. These include λ phage replication protein λO, master regulator of stationary phase RpoS, and SsrA-tagged proteins. Globally, TF acts to enhance the degradation of about 2% of newly synthesized proteins. TF is found to interact through multiple sites with ClpX in a highly dynamic fashion to promote protein degradation. This chaperone-protease cooperation constitutes a unique and likely ancestral aspect of cellular protein homeostasis in which TF acts as an adaptor for ClpXP.
Dengue, a mosquitoborne flavivirus infection, is increasingly a disease of older adults who are more likely to have chronic diseases that confer risk for severe outcomes of dengue infection. In a ...population-based study in Taiwan, adjusted risks for dengue-related hospitalization, intensive care unit admission, and death increased progressively with age.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Hsp104 is a ring-forming protein disaggregase that rescues stress-damaged proteins from an aggregated state. To facilitate protein disaggregation, Hsp104 cooperates with Hsp70 and Hsp40 chaperones ...(Hsp70/40) to form a bi-chaperone system. How Hsp104 recognizes its substrates, particularly the importance of the N domain, remains poorly understood and multiple, seemingly conflicting mechanisms have been proposed. Although the N domain is dispensable for protein disaggregation, it is sensitive to point mutations that abolish the function of the bacterial Hsp104 homolog in vitro, and is essential for curing yeast prions by Hsp104 overexpression in vivo. Here, we present the crystal structure of an N-terminal fragment of Saccharomyces cerevisiae Hsp104 with the N domain of one molecule bound to the C-terminal helix of the neighboring D1 domain. Consistent with mimicking substrate interaction, mutating the putative substrate-binding site in a constitutively active Hsp104 variant impairs the recovery of functional protein from aggregates. We find that the observed substrate-binding defect can be rescued by Hsp70/40 chaperones, providing a molecular explanation as to why the N domain is dispensable for protein disaggregation when Hsp70/40 is present, yet essential for the dissolution of Hsp104-specific substrates, such as yeast prions, which likely depends on a direct N domain interaction.
Rankine cycles using organic fluids (as categorized into three groups: wet, dry, and isentropic fluids) as working fluids in converting low-grade energy are investigated in this study. The main ...purpose is to identify suitable working fluids which may yield high system efficiencies in an organic Rankine cycle (ORC) system. Efficiencies of ORC systems are calculated based on an assumption that the inlet condition of the working fluid entering turbine is in saturated vapor phase. Parameters under investigation are turbine inlet temperature, turbine inlet pressure, condenser exit temperature, turbine exit quality, overall irrversibility, and system efficiency. The low-grade energy source can be obtained from a solar pond or/and an ocean thermal energy conversion (OTEC) system. Results indicate that wet fluids with very steep saturated vapor curves in T-s diagram have a better overall performance in energy conversion efficiencies than that of dry fluids. It can also be shown that all the working fluids have a similar behavior of the efficiency-condenser exit temperature relationship. Furthermore, an appropriate combination of solar energy and an ORC system with a higher turbine inlet temperature and a lower condenser temperature (as operated deeply under sea level) would provide an economically feasible and environment-friendly renewable energy conversion system.
Influenza directly or indirectly contributes to the four leading causes of global mortality, at rates that are highest in older adults. As the proportion of older adults in the Korean population is ...greater than in most other countries, influenza prevention is a greater public health priority in Korea than elsewhere. Conventional inactivated influenza vaccine (IIV) is less immunogenic and efficacious (-50%) in older than in young adults, but adjuvanting the vaccine with oil-in-water emulsion MF59® increases immunogenicity, resulting in comparatively higher levels of hemagglutination inhibition antibodies and greater protection against all influenza, as well as cases requiring hospitalization. A recent observational study demonstrated that the adjuvanted vaccine protected older adults against influenza in a year when nonadjuvanted IIV was ineffective. In another multiyear study, the adjuvanted vaccine was estimated to be 25% more effective in preventing pneumonia and influenza hospitalizations compared to nonadjuvanted vaccine. Although MF59-adjuvanted vaccine is transiently more reactogenic than nonadjuvanted vaccine, there is no evidence that it increases risks for serious adverse events, including those with an autoimmune etiology. Experience thus far indicates a favorable balance of benefit to risk for MF59. This may reflect the adjuvant's mechanism of action in which the squalene oil emulsion increases antibody responses to co-administered antigen without acting more generally as an immunopotentiator.
In this era of unprecedented longevity, healthy aging is an important public health priority. Avoiding or shortening the period of disability or dementia before death is critical to achieving the ...defining objectives of healthy aging, namely to develop and maintain functional capabilities that enable wellbeing in older age. The first step is to identify people who are at risk and then to implement effective primary interventions. Geriatricians have identified a distinct clinical phenotype of concurrent physical frailty and cognitive impairment, which predicts high risk of incident dementia and disability and is potentially reversible. Differing operational definitions for this phenotype include “cognitive frailty”, “motoric cognitive risk syndrome” and the recently proposed “physiocognitive decline syndrome (PCDS)”. PCDS is defined as concurrent mobility impairment no disability (MIND: slow gait or/and weak handgrip) and cognitive impairment no dementia (CIND: ≥1.5 SD below the mean for age-, sex-, and education-matched norms in any cognitive domain but without dementia). By these criteria, PCDS has a prevalence of 10–15% among community-dwelling older persons without dementia or disability, who are at increased risk for incident disability (HR 3.9, 95% CI 3.0–5.1), incident dementia (HR 3.4, 95% CI 2.4–5.0) and all-cause mortality (HR 6.7, 95% CI 1.8–26.1). Moreover, PCDS is associated with characteristic neuroanatomic changes in the cerebellum and hippocampus, and their neurocircuitry, which are distinct from neuroimaging features in normal aging and common dementia syndromes. Basic research and longitudinal clinical studies also implicate a hypothetical muscle-brain axis in the pathoetiology of PCDS. Most important, community-dwelling elders with PCDS who participated in a multidomain intervention had significant improvements in global cognitive function, and especially in the subdomains of naming and concentration. Our proposed operational definition of PCDS successfully identifies an appreciable population of at-risk older people, establishes a distinct phenotype with an apparently unique pathoetiology, and is potentially reversible. We now need further studies to elucidate the pathophysiology of PCDS, to validate neuroimaging features and muscle-secreted microRNA biomarkers, and to evaluate the effectiveness of sustained multidomain interventions.
A three-dimensional (3D) Dirac semimetal is a novel state of quantum matter which has recently attracted much attention as an apparent 3D version of graphene. In this paper, we report results on the ...electronic structure of the 3D Dirac semimetal Na sub(3) Bi at a surface that reveals its nontrivial ground state. Our studies reveal that the two 3D Dirac cones go through a topological change in the constant energy contour as a function of the binding energy, featuring a Lifshitz point, which is missing in a strict 3D analog of graphene. Our results identify an example of a band saddle-point singularity in 3D Dirac materials. This is in contrast to its two-dimensional analogs such as graphene and the Dirac surface states of a topological insulator. The observation of multiple Dirac nodes in Na sub(3) Bi connecting via a Lifshitz point along its crystalline rotational axis away from the Kramers point serves as a decisive signature for the symmetry-protected nature of the Dirac semimetal's topological bulk ground state.
Hyperperfusion syndrome is a devastating complication of carotid stent placement. The shortening of cerebral circulation time after stent placement is seen as a good indicator of the development of ...hyperperfusion syndrome. The purpose of our study was to evaluate whether patients with ipsilateral transverse sinus stenosis are prone to having shortened cerebral circulation time after stent placement, subsequently leading to the possible development of hyperperfusion syndrome.
Forty-nine patients with >70% unilateral carotid stenosis undergoing stent placement were recruited for analysis. Group A consisted of patients with a stenotic ipsilateral transverse sinus >50% greater than the diameter of the contralateral transverse sinus; the remaining patients were in group B. Quantitative DSA was used to calculate cerebral circulation time. Cerebral circulation time was defined as the time difference between the relative time to maximal intensity of ROIs in the proximal internal carotid artery and the internal jugular vein. ΔCCT was defined as cerebral circulation time before stent placement minus cerebral circulation time after stent placement. ΔCCT, white matter hyperintensity signals, and sulcal effacement in MR imaging were compared between the 2 groups.
ΔCCT was significantly shorter in group A (0.65 ± 1.3) than in group B (-0.12 ± 1.4). Three patients had white matter hyperintensity signals in group A, and 1 developed hyperperfusion syndrome. Group B showed no MR imaging signs of hyperperfusion syndrome.
Ipsilateral hypoplastic transverse sinus was associated with prolonged cerebral circulation time before stent placement and greatly shortened cerebral circulation time after stent placement. Inadequate venous drainage might play a role in impaired cerebral autoregulation and might influence the development of poststenting hyperperfusion syndrome.
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