Skeletons are formed in a wide variety of shapes, sizes, and compositions of organic and mineral components. Many invertebrate skeletons are constructed from carbonate or silicate minerals, whereas ...vertebrate skeletons are instead composed of a calcium phosphate mineral known as apatite. No one yet knows why the dynamic vertebrate skeleton, which is continually rebuilt, repaired, and resorbed during growth and normal remodeling, is composed of apatite. Nor is the control of bone and calcifying cartilage mineralization well understood, though it is thought to be associated with phosphate-cleaving proteins. Researchers have assumed that skeletal mineralization is also associated with non-crystalline, calcium- and phosphate-containing electron-dense granules that have been detected in vertebrate skeletal tissue prepared under non-aqueous conditions. Again, however, the role of these granules remains poorly understood. Here, we review bone and growth plate mineralization before showing that polymers of phosphate ions (polyphosphates: (PO(3)(-))(n)) are co-located with mineralizing cartilage and resorbing bone. We propose that the electron-dense granules contain polyphosphates, and explain how these polyphosphates may play an important role in apatite biomineralization.
The enzymatic formation (condensation) and destruction (hydrolytic degradation) of polyphosphates offers a simple mechanism for enzymatic control of phosphate accumulation and the relative saturation of apatite. Under circumstances in which apatite mineral formation is undesirable, such as within cartilage tissue or during bone resorption, the production of polyphosphates reduces the free orthophosphate (PO(4)(3-)) concentration while permitting the accumulation of a high total PO(4)(3-) concentration. Sequestering calcium into amorphous calcium polyphosphate complexes can reduce the concentration of free calcium. The resulting reduction of both free PO(4)(3-) and free calcium lowers the relative apatite saturation, preventing formation of apatite crystals. Identified in situ within resorbing bone and mineralizing cartilage by the fluorescent reporter DAPI (4',6-diamidino-2-phenylindole), polyphosphate formation prevents apatite crystal precipitation while accumulating high local concentrations of total calcium and phosphate. When mineralization is required, tissue non-specific alkaline phosphatase, an enzyme associated with skeletal and cartilage mineralization, cleaves orthophosphates from polyphosphates. The hydrolytic degradation of polyphosphates in the calcium-polyphosphate complex increases orthophosphate and calcium concentrations and thereby favors apatite mineral formation. The correlation of alkaline phosphatase with this process may be explained by the destruction of polyphosphates in calcifying cartilage and areas of bone formation.
We hypothesize that polyphosphate formation and hydrolytic degradation constitute a simple mechanism for phosphate accumulation and enzymatic control of biological apatite saturation. This enzymatic control of calcified tissue mineralization may have permitted the development of a phosphate-based, mineralized endoskeleton that can be continually remodeled.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Human cytomegalovirus (HCMV) replication requires host metabolism. Infection alters the activity in multiple metabolic pathways, including increasing fatty acid elongation and lipid synthesis. The ...virus-host interactions regulating the metabolic changes associated with replication are essential for infection. While multiple host factors, including kinases and transcription factors, important for metabolic changes that occur following HCMV infection have been identified, little is known about the viral factors required to alter metabolism. In this study, we tested the hypothesis that pUL37x1 is important for the metabolic remodeling that is necessary for HCMV replication using a combination of metabolomics, lipidomics, and metabolic tracers to measure fatty acid elongation. We observed that fibroblast cells infected with wild-type (WT) HCMV had levels of metabolites similar to those in cells infected with a mutant virus lacking the UL37x1 gene,
UL37x1. However, we found that relative to WT-infected cells,
UL37x1-infected cells had reduced levels of two host proteins that were previously demonstrated to be important for lipid metabolism during HCMV infection: fatty acid elongase 7 (ELOVL7) and the endoplasmic reticulum (ER) stress-related kinase PERK. Moreover, we observed that HCMV infection results in an increase in phospholipids with very-long-chain fatty acid tails (PL-VLCFAs) that contain 26 or more carbons in one of their two tails. The levels of many PL-VLCFAs were lower in
UL37x1-infected cells than in WT-infected cells. Overall, we conclude that although pUL37x1 is not necessary for network-wide metabolic changes associated with HCMV infection, it is important for the remodeling of a subset of metabolic changes that occur during infection.
Human cytomegalovirus (HCMV) is a common pathogen that asymptomatically infects most people and establishes a lifelong infection. However, HCMV can cause end-organ disease that results in death in the immunosuppressed and is a leading cause of birth defects. HCMV infection depends on host metabolism, including lipid metabolism. However, the viral mechanisms for remodeling of metabolism are poorly understood. In this study, we demonstrate that the viral UL37x1 protein (pUL37x1) is important for infection-associated increases in lipid metabolism, including fatty acid elongation to produce very-long-chain fatty acids (VLCFAs). Furthermore, we found that HCMV infection results in a significant increase in phospholipids, particularly those with VLCFA tails (PL-VLCFAs). We found that pUL37x1 was important for the high levels of fatty acid elongation and PL-VLCFA accumulation that occur in HCMV-infected cells. Our findings identify a viral protein that is important for changes in lipid metabolism that occur following HCMV infection.
► Participants included 393 university students. ► A negative binomial regression strategy was used to analyse count data. ► Openness was associated with spending time and having friends on Facebook. ...► Loneliness was associated with having Facebook friends.
This study examined the relationship between three of the “Big Five” traits (neuroticism, extraversion, and openness), self-esteem, loneliness and narcissism, and Facebook use. Participants were 393 first year undergraduate psychology students from a medium-sized Australian university who completed an online questionnaire. Negative binomial regression models showed that students with higher openness levels reported spending more time on Facebook and having more friends on Facebook. Interestingly, students with higher levels of loneliness reported having more Facebook friends. Extraversion, neuroticism, self-esteem and narcissism did not have significant associations with Facebook use. It was concluded that students who are high in openness use Facebook to connect with others in order to discuss a wide range of interests, whereas students who are high in loneliness use the site to compensate for their lack of offline relationships.
Summary
Tetralogy of Fallot (TOF) has four anatomic features: right ventricular hypertrophy (RVH), ventriculoseptal defect (VSD), overriding aorta and right ventricular outflow tract obstruction ...(RVOT) with an occurrence of 3.9 /10,000 births. The pathophysiologic effects in TOF are largely determined by the degree of RVOT and not the VSD. Intra‐operative anesthetic management is also dependent on the degree of RVOT obstruction and influenced by the extent of surgical RVOT repair.
Human cytomegalovirus (HCMV) replication depends on the activities of several host regulators of metabolism. Hypoxia-inducible factor 1α (HIF1α) was previously proposed to support virus replication ...through its metabolic regulatory function. HIF1α protein levels rise in response to HCMV infection in nonhypoxic conditions, but its effect on HCMV replication was not investigated. We addressed the role of HIF1α in HCMV replication by generating primary human cells with HIF1α knocked out using CRISPR/Cas9. When HIF1α was absent, we found that HCMV replication was enhanced, showing that HIF1α suppresses viral replication. We used untargeted metabolomics to determine if HIF1α regulates metabolite concentrations in HCMV-infected cells. We discovered that in HCMV-infected cells, HIF1α suppresses intracellular and extracellular concentrations of kynurenine. HIF1α also suppressed the expression of indoleamine 2,3-dioxygenase 1 (IDO1), the rate-limiting enzyme in kynurenine synthesis. In addition to its role in tryptophan metabolism, kynurenine acts as a signaling messenger by activating aryl hydrocarbon receptor (AhR). Inhibiting AhR reduces HCMV replication, while activating AhR with an exogenous ligand increases virus replication. Moreover, we found that feeding kynurenine to cells promotes HCMV replication. Overall, our findings indicate that HIF1α reduces HCMV replication by regulating metabolism and metabolite signaling.
Viruses, including human cytomegalovirus (HCMV), reprogram cellular metabolism using host metabolic regulators to support virus replication. Alternatively, in response to infection, the host can use metabolism to limit virus replication. Here, our findings show that the host uses hypoxia-inducible factor 1α (HIF1α) as a metabolic regulator to reduce HCMV replication. Further, we found that HIF1α suppresses kynurenine synthesis, a metabolite that can promote HCMV replication by signaling through the aryl hydrocarbon receptor (AhR). In infected cells, the rate-limiting enzyme in kynurenine synthesis, indoleamine 2,3-dioxygenase 1 (IDO1), is suppressed by a HIF1α-dependent mechanism. Our findings describe a functional connection between HIF1α, IDO1, and AhR that allows HIF1α to limit HCMV replication through metabolic regulation, advancing our understanding of virus-host interactions.
The activity of a self-sufficient cytochrome P450 enzyme, CYP505D6, from the lignin-degrading basidiomycete
was characterized. Recombinant CYP505D6 was produced in
and purified. In the presence of ...NADPH, CYP505D6 used a series of saturated fatty alcohols with C
carbon chain lengths as the substrates. Hydroxylation occurred at the ω-1 to ω-6 positions of such substrates with C
carbon chain lengths, except for 1-dodecanol, which was hydroxylated at the ω-1 to ω-7 positions. Fatty acids were also substrates of CYP505D6. Based on the sequence alignment, the corresponding amino acid of Tyr51, which is located at the entrance to the active-site pocket in CYP102A1, was Val51 in CYP505D6. To understand the diverse hydroxylation mechanism, wild-type CYP505D6 and its V51Y variant and wild-type CYP102A1 and its Y51V variant were generated, and the products of their reaction with dodecanoic acid were analyzed. Compared with wild-type CYP505D6, its V51Y variant generated few products hydroxylated at the ω-4 to ω-6 positions. The products generated by wild-type CYP102A1 were hydroxylated at the ω-1 to ω-4 positions, whereas its Y51V variant generated ω-1 to ω-7 hydroxydodecanoic acids. These observations indicated that Val51 plays an important role in determining the regiospecificity of fatty acid hydroxylation, at least that at the ω-4 to ω-6 positions. Aromatic compounds, such as naphthalene and 1-naphthol, were also hydroxylated by CYP505D6. These findings highlight a unique broad substrate spectrum of CYP505D6, rendering it an attractive candidate enzyme for the biotechnological industry.
is a white-rot fungus whose metabolism of lignin, aromatic pollutants, and lipids has been most extensively studied. This fungus harbors 154 cytochrome P450-encoding genes in the genome. As evidenced in this study,
CYP505D6, a fused protein of P450 and its reductase, hydroxylates fatty alcohols (C
) and fatty acids (C
) at the ω-1 to ω-7 or ω-1 to ω-6 positions, respectively. Naphthalene and 1-naphthol were also hydroxylated, indicating that the substrate specificity of CYP505D6 is broader than those of the known fused proteins CYP102A1 and CYP505A1. The substrate versatility of CYP505D6 makes this enzyme an attractive candidate for biotechnological applications.
Boredom coping strategies were incorporated with control-value theory variables of control, value, boredom and academic performance to test an integrated model of the antecedents and effects of ...boredom experienced while studying among university students. A diverse sample of 177 Australian university students with a mean age of 29.64 years (SD = 10.03 years) completed an online survey for the study. Independently, students' lower appraisals of value and control for their course of study were associated with higher experiences of boredom. Additionally, a conditional process analysis revealed dually moderated mediation where the interaction of control and value appraisals negatively predicted experience of boredom while studying, and the combination of higher boredom and a high tendency for behavioural avoidance coping was subsequently linked to lower academic performance. Practical implications for students and universities are discussed, as well as suggestions about future research to further extend our understanding in these important areas of research. Author abstract
Objectives
To evaluate the incidence, severity, and outcomes of pulmonary hemorrhage in children with Alagille syndrome (AGS) undergoing cardiac catheterization, and to find variables associated with ...hemorrhage in this population.
Background
Children with AGS have a high incidence of bleeding complications during invasive procedures. It has been our impression that catheterization‐associated pulmonary hemorrhage is more common in children with AGS, but there are no published data on this topic.
Methods
This was a retrospective single institution study of children with AGS undergoing catheterization from 2010 to 2018. Pulmonary hemorrhage was defined as angiographic or fluoroscopic evidence of extravasated blood in the lung parenchyma, or blood suctioned from the endotracheal tube with documentation of pulmonary hemorrhage by the anesthesiologist or intensivist. Univariate comparisons were made between catheterizations that did and did not have pulmonary hemorrhage.
Results
Thirty children with AGS underwent 87 catheterizations, 32 (37%) with interventions on the branch pulmonary arteries (PA). There were 26 (30%) procedures with hemorrhage, the majority (65%) of which were self‐limited or required less than 24 hr of mechanical ventilation. Moderate and severe hemorrhage occurred only in children with tetralogy of Fallot (TOF; 5 of 14, 36%). A higher right ventricle to aorta systolic pressure ratio (1.0 0.85–1.1 vs. 0.88 0.59–1.0, p = .029) and interventions on the branch PAs (14 of 26, 54% vs. 18 of 61, 30%, p = .032) were associated with hemorrhage.
Conclusions
Pulmonary hemorrhage was common in children with AGS undergoing both intervention and diagnostic cardiac catheterization, and was associated with TOF, higher RV to aorta pressure ratio, and interventions on the branch PAs.
This study explored cyberbullying, coping resources and coping styles in a sample of 107 10- to 12-year-old Australian primary school students. Approximately 13% of participants reported experiencing ...single episodes of cyberbullying victimisation, while almost half of the participants (48.6%) reported being repeatedly cyberbullied. Technological responses employed by cyberbullying victims included blocking, deleting, and changing passwords. Those who reported a single episode of cyberbullying had higher levels of self-esteem compared to the never cyberbullied or repeatedly cyberbullied groups, but there were no significant differences in attachment, locus of control, and coping styles. These findings have important implications for teachers, parents, school psychologists, and researchers in terms of defining and operationalising cyberbullying, and developing cyberbullying interventions for primary school children.
Introduction
Platelet activation by mechanical means such as shear stress exposure, is a vital driver of thrombotic risk in implantable blood-contacting devices used in the treatment of heart ...failure. Lipids are essential in platelets activation and have been studied following biochemical activation. However, little is known regarding lipid alterations occurring with mechanical shear-mediated platelet activation.
Methods
Here, we determined if shear-activation of platelets induced lipidome changes that differ from those associated with biochemically-mediated platelet activation. We performed high-resolution lipidomic analysis on purified platelets from four healthy human donors. For each donor, we compared the lipidome of platelets that were non-activated or activated by shear, ADP, or thrombin treatment.
Results
We found that shear activation altered cell-associated lipids and led to the release of lipids into the extracellular environment. Shear-activated platelets released 21 phospholipids and sphingomyelins at levels statistically higher than platelets activated by biochemical stimulation.
Conclusions
We conclude that shear-mediated activation of platelets alters the basal platelet lipidome. Further, these alterations differ and are unique in comparison to the lipidome of biochemically activated platelets. Many of the released phospholipids contained an arachidonic acid tail or were phosphatidylserine lipids, which have known procoagulant properties. Our findings suggest that lipids released by shear-activated platelets may contribute to altered thrombosis in patients with implanted cardiovascular therapeutic devices.
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