Imprecision of high-sensitivity cardiac troponin assays at the female 99th-percentile.

BACKGROUND: An analytical benchmark for high-sensitivity cardiac troponin (hs-cTn) assays is to achieve a coefficient of variation (CV) of ≤ 10.0 % at the 99th percentile upper reference limit (URL) used for the diagnosis of myocardial infarction. Few prospective multicenter studies have evaluated assay imprecision and none have determined precision at the female URL which is lower than the male URL for all cardiac troponin assays. METHODS: Human serum and plasma matrix samples were constructed to yield hs-cTn concentrations near the female URLs for the Abbott, Beckman, Roche, and Siemens hs-cTn assays. These materials were sent (on dry ice) to 35 Canadian hospital laboratories (n = 64 instruments evaluated) participating in a larger clinical trial, with instructions for storage, handling, and monthly testing over one year. The mean concentration, standard deviation, and CV for each instrument type and an overall pooled CV for each manufacturer were calculated. RESULTS: The CVs for all individual instruments and overall were ≤ 10.0 % for two manufacturers (Abbott CVpooled = 6.3 % and Beckman CVpooled = 7.0 %). One of four Siemens Atellica instruments yielded a CV > 10.0 % (CVpooled = 7.7 %), whereas 15 of 41 Roche instruments yielded CVs > 10.0 % at the female URL of 9 ng/L used worldwide (6 cobas e411, 1 cobas e601, 4 cobas e602, and 4 cobas e801) (CVpooled = 11.7 %). Four Roche instruments also yielded CVs > 10.0 % near the female URL of 14 ng/L used in the United States (CVpooled = 8.5 %). CONCLUSIONS: The number of instruments achieving a CV ≤ 10.0 % at the female 99th-percentile URL varies by manufacturer and by instrument. Monitoring assay precision at the female URL is necessary for some assays to ensure optimal use of this threshold in clinical practice.

Outsourcing Intersystem Crossing without Heavy Atoms: Energy Transfer Dynamics in PyridoneBODIPY-C60 Complexes.

The excited state dynamics in two fully characterized pyridoneBODIPY-fullerene complexes were investigated using time-resolved spectroscopy. Photoexcitation was initially localized on the pyridoneBODIPY chromophore. The energy was rapidly transferred to the fullerene, which subsequently underwent ISC to form a triplet state and returned the energy to the pyridoneBODIPY via triplet-triplet energy transfer. This ping-pong energy transfer mechanism resulted in efficient (>85%) overall conversion of the excited state pyridoneBODIPY constituent despite a complete lack of ISC in the pyridoneBODIPY in the absence of the fullerene partner. The small difference in attachment chemistry for the fullerene did not impact the initial singlet energy transfer. However, the N-methylpyrrolidine bridge did slow both the triplet-triplet energy transfer and the ultimate relaxation rate of the final triplet state when compared to an isoxazole-based bridge. The rates of each step were quantified, and computational predictions were used to complement the proposed mechanism and energetics. The result demonstrated efficient triplet sensitization of a strong chromophore that lacks significant spin-orbit coupling.

Light-Driven Hydrodefluorination of Electron-Rich Aryl Fluorides by an Anionic Rhodium-Gallium Photoredox Catalyst.

An anionic Rh-Ga complex catalyzed the hydrodefluorination of challenging C-F bonds in electron-rich aryl fluorides and trifluoromethylarenes when irradiated with violet light in the presence of H2 , a stoichiometric alkoxide base, and a crown-ether additive. Based on theoretical calculations, the lowest unoccupied molecular orbital (LUMO), which is delocalized across both the Rh and Ga atoms, becomes singly occupied upon excitation, thereby poising the Rh-Ga complex for photoinduced single-electron transfer (SET). Stoichiometric and control reactions support that the C-F activation is mediated by the excited anionic Rh-Ga complex. After SET, the proposed neutral Rh0 intermediate was detected by EPR spectroscopy, which matched the spectrum of an independently synthesized sample. Deuterium-labeling studies corroborate the generation of aryl radicals during catalysis and their subsequent hydrogen-atom abstraction from the THF solvent to generate the hydrodefluorinated arene products. Altogether, the combined experimental and theoretical data support an unconventional bimetallic excitation that achieves the activation of strong C-F bonds and uses H2 and base as the terminal reductant.

Goitered Gazelle Gazella subgutturosa Responded to Human Disturbance by Increasing Vigilance Rather than Changing the Group Size.

Nonlethal human disturbances have been confirmed to have a negative effect on wildlife in a variety of ways, including on behaviors. In many studies, the impact of human disturbances on gregarious species of wildlife is assessed through changes in their social organization and vigilance. In our study in the Kalamaili Nature Reserve, China, we wanted to estimate the impacts of differing levels of human disturbances on two different group types (mixed-sex and all-male) of goitered gazelle, Gazella subgutturosa, living in three functional zones (experimental, buffer, and core zones), which represent high, medium, and low human disturbance levels, respectively. In addition, we studied the time spent vigilant as a function of group size with different levels of human disturbances in the three zones. In general, mixed-sex gazelle groups were of similar sizes in the three different zones, while all-male groups slightly differed in their sizes between the experimental and buffer zones. This may indicate that human disturbances have varying effects on the different group types, with smaller-sized, single-sex groups being more significantly affected by human disturbances than larger-sized, mixed-sex groups. Goitered gazelle showed higher vigilance levels in the experimental zone than in the two other zones. A trend of decreasing vigilance varying linearly with group size was also found in the three zones, and the rate of decrease was higher in the experimental zone. Increased habitat fragmentation and human activities brought goitered gazelle and humans closer together in the core zone. Therefore, stopping mining activities and returning the reserve to a continuous habitat with fewer environmental disturbances is the best way to establish and protect a stable population of this endangered species of gazelle.

Different environmental requirements of female and male Siberian ibex, Capra sibirica.

In sexually dimorphic species, males and females may select different habitat for greater fitness. However, the key factors that play a leading role between sexes in habitat selection are still poorly understood. In this paper, we investigated the possible causes of the differences in habitat preference between male and female Siberian ibex (Capra sibirica) living in the Tianshan Mountains (China). Using the Maximum entropy model, we found that the ruggedness and elevation of the terrain were the most important factors affecting habitat selection in Siberian ibex. Females preferred the most rugged terrain to increase the security of their young and themselves, while males favored moderately rugged terrain to provide sufficient safety from predators, and availability of suitable forage simultaneously. Females used a wider variety of elevations to search for newly emerged vegetation for its higher nutritional value, while males preferred more elevated slopes to avoid the higher temperatures and greater presence of biting insects found at the lower elevations. In addition, females were associated more with rivers due to their higher water demands. The differences in habitat selection between Siberian ibex males and females depend on multiple considerations, but only a limited number of key factors determine their actual distribution.

Fully Conjugated Pyrene-BODIPY and Pyrene-BODIPY-Ferrocene Dyads and Triads: Synthesis, Characterization, and Selective Noncovalent Interactions with Nanocarbon Materials.

Several pyrene-boron-dipyrromethene (BODIPY) and pyrene-BODIPY-ferrocene derivatives with a fully conjugated pyrene fragment appended to the α-position(s) of the BODIPY core have been prepared by Knoevenagel condensation reaction and characterized by one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR), UV-vis, fluorescence spectroscopy, high-resolution mass spectrometry as well as X-ray crystallography. The redox properties of new donor-acceptor BODIPY dyads and triads were studied by electrochemical (cyclic voltammetry (CV) and differential pulse voltammetry (DPV)) and spectroelectrochemical approaches. Formation of weakly bonded noncovalent complexes between the new pyrene-BODIPYs and nanocarbon materials (C60, C70, single-walled carbon nanotube (SWCNT), and graphene) was studied by UV-vis, steady-state fluorescent, and time-resolved transient absorption spectroscopy. UV-vis and fluorescent spectroscopy are indicative of the much stronger and selective interaction between new dyes and (6,5)-SWCNT as well as graphene compared to that of C60 and C70 fullerenes. In agreement with these data, transient absorption spectroscopy provided no evidence for any significant change in excited-state lifetime or photoinduced charge transfer between pyrene-BODIPYs and C60 or C70 fullerenes when the pyrene-BODIPY chromophores were excited into the lowest-energy singlet excited state. Density functional theory (DFT) and time-dependent DFT (TDDFT) calculations suggest that the pyrene fragments are fully conjugated into the π-system of BODIPY core, which correlates well with the experimental data.

Two-photon uncaging of bioactive thiols in live cells at wavelengths above 800 nm.

Photoactivatable protecting groups (PPGs) are useful for a broad range of applications ranging from biology to materials science. In chemical biology, induction of biological processes via photoactivation is a powerful strategy for achieving spatiotemporal control. The importance of cysteine, glutathione, and other bioactive thiols in regulating protein structure/activity and cell redox homeostasis makes modulation of thiol activity particularly useful. One major objective for enhancing the utility of photoactivatable protecting groups (PPGs) in living systems is creating PPGs with longer wavelength absorption maxima and efficient two-photon (TP) absorption. Toward these objectives, we developed a carboxyl- and dimethylamine-functionalized nitrodibenzofuran PPG scaffold (cDMA-NDBF) for thiol photoactivation, which has a bathochromic shift in the one-photon absorption maximum from λmax = 315 nm with the unfunctionalized NDBF scaffold to λmax = 445 nm. While cDMA-NDBF-protected thiols are stable in the presence of UV irradiation, they undergo efficient broad-spectrum TP photolysis at wavelengths as long as 900 nm. To demonstrate the wavelength orthogonality of cDMA-NDBF and NDBF photolysis in a biological setting, caged farnesyltransferase enzyme inhibitors (FTI) were prepared and selectively photoactivated in live cells using 850-900 nm TP light for cDMA-NDBF-FTI and 300 nm UV light for NDBF-FTI. These experiments represent the first demonstration of thiol photoactivation at wavelengths above 800 nm. Consequently, cDMA-NDBF-caged thiols should have broad applicability in a wide range of experiments in chemical biology and materials science.

Probing Electronic Communication and Excited-State Dynamics in the Unprecedented Ferrocene-Containing Zinc MB-DIPY.

The electronic communication between two ferrocene groups in the electron-deficient expanded aza-BODIPY analogue of zinc manitoba-dipyrromethene (MB-DIPY) was probed by spectroscopic, electrochemical, spectroelectrochemical, and theoretical methods. The excited-state dynamics involved sub-ps formation of the charge-separated state in the organometallic zinc MB-DIPYs, followed by recovery of the ground state via charge recombination in 12 ps. The excited-state behavior was contrasted with that observed in the parent complex that lacked the ferrocene electron donors and has a much longer excited-state lifetime (670 ps for the singlet state). Much longer decay times observed for the parent complex without ferrocene confirm that the main quenching mechanism in the ferrocene-containing 4 is reflective of the ultrafast ferrocene-to-MB-DIPY core charge transfer (CT).

Photodetachment and Electron Dynamics in 1-Butyl-1-methyl-pyrrolidinium Dicyanamide.

The ultrafast transient absorption spectrum of 1-butyl-1-methyl-pyrrolidinium dicyanamide, [Pyr1,4+][DCA-], was measured in the visible and near-infrared (IR) spectral regions. Excitation of the liquid at 4.6 eV created initially delocalized and highly reactive electrons that either geminately recombined (69%) or localized onto a cavity with a time constant of ∼300 fs. Electron localization was reflected in the evolution of the TA spectrum and the time-dependent loss of reactivity with a dichloromethane quencher. The delocalized initial state and spectrum of the free electrons were consistent with computational predictions by Xu and Margulis [ J. Phys. Chem. B, 2015, 119, 532-542] on excess electrons in [Pyr1,4+][DCA-]. The computational study considered two possible localization mechanisms for excess electrons, localization on ions, and localization on cavities. In the case of photogenerated electron-hole pairs, the results presented here demonstrate localization to cavities as the dominant channel. Following localization onto a cavity, the free electrons underwent solvation and loss of reactivity with the quencher with rates that slowed in time. The dynamics were similar to an analogous prior study on the related liquid [Pyr1,x+][NTf2-]. One significant difference was the larger yield of free electrons from photoexcitation of [Pyr1,4+][DCA-]. This was found to primarily reflect more efficient localization onto cavities rather than a slower geminate recombination rate.

A simplified diagnosis algorithm for dysbetalipoproteinemia.

BACKGROUND: Dysbetalipoproteinemia (DBL) is a disease of remnant lipoprotein accumulation caused by a defective apolipoprotein (apo) E and is associated with a considerable atherogenic burden. However, there exists confusion concerning the diagnosis of this disorder, and as a consequence, misdiagnosis is frequent. OBJECTIVE: The objective of the present study is to propose an algorithm for the diagnosis of DBL using simple clinical variables. METHODS: In a large cohort of 12,434 dyslipidemic patients, 4891 patients presented with mixed dyslipidemia (total cholesterol ≥ 5.2 mmol/L [200 mg/dL] and triglycerides ≥ 2.0 mmol/L [175 mg/dL]), and 188 DBL patients were identified based on the presence of an elevated very-low-density lipoprotein cholesterol/triglyceride ratio and were carriers of apoE2/E2. The APOE genotype or phenotype as well as the lipoprotein ultracentrifugation results were available for all patients. RESULTS: Among the laboratory variables associated with the lipid profile, the non-high-density lipoprotein cholesterol (HDL-C)/apoB ratio was the best predictor of DBL diagnosis based on the C-statistic. Previous proposed criteria had either low sensitivity or low specificity for the diagnosis of DBL. Using a non-HDL-C/apoB cut point of 3.69 mmol/g (1.43 in conventional units) followed by the presence of apoE2/E2 resulted in a good sensitivity (94.8%), negative predictive value (99.8%), specificity (99.6%), positive predictive value (88.5%), accuracy (99.4%), and area under the curve (0.97 [0.95-0.99]) for the prediction of DBL. CONCLUSION: We therefore propose a 3-step algorithm for the diagnosis of DBL using total cholesterol and triglycerides as a first step, the non-HDL-C/apoB ratio as a second screening criterion and finally the APOE genotype, lipoprotein ultracentrifugation, or electrophoresis as a confirmatory test.

Methoxy-Substituted Nitrodibenzofuran-Based Protecting Group with an Improved Two-Photon Action Cross-Section for Thiol Protection in Solid Phase Peptide Synthesis.

Photoremovable caging groups are useful for biological applications because the deprotection process can be initiated by illumination with light without the necessity of adding additional reagents such as acids or bases that can perturb biological activity. In solid phase peptide synthesis (SPPS), the most common photoremovable group used for thiol protection is the o-nitrobenzyl group and related analogues. In earlier work, we explored the use of the nitrodibenzofuran (NDBF) group for thiol protection and found it to exhibit a faster rate toward UV photolysis relative to simple nitroveratryl-based protecting groups and a useful two-photon cross-section. Here, we describe the synthesis of a new NDBF-based protecting group bearing a methoxy substituent and use it to prepare a protected form of cysteine suitable for SPPS. This reagent was then used to assemble two biologically relevant peptides and characterize their photolysis kinetics in both UV- and two-photon-mediated reactions; a two-photon action cross-section of 0.71-1.4 GM for the new protecting group was particularly notable. Finally, uncaging of these protected peptides by either UV or two-photon activation was used to initiate their subsequent enzymatic processing by the enzyme farnesyltransferase. These experiments highlight the utility of this new protecting group for SPPS and biological experiments.

Vigilance behaviour in Siberian ibex (Capra sibirica): Effect of group size, group type, sex and age.

Gregarious prey species modify their behaviours in response to predation risk in two ways: by increasing vigilance level or enlarging herd size. However, individuals of various sex and age have different responses to the same danger, and even the same individuals react differently depending on their status during biological events or within group types. But how these factors influence the interactions between vigilance level and group size is still poorly understood. Therefore, we studied this phenomenon by observing and analyzing the behaviours of the Siberian ibex (Capra sibirica) in the Eastern Tian-Shan Mountains (China). We found that similar to many other gregarious ungulates, Siberian ibex demonstrated a decrease in vigilance level with an increase in group size, since staying in larger groups increased the probability of predator detection and reduced the possibility of being captured. In general, males were more vigilant than females during the rut due to the sharp increase in their social alertness to achieve greater success in reproduction. In contrast, females were more vigilant than males out of rutting time, particularly significantly following parturition, since mothers spent a lot of their energy in maternal care, which coupled with having small and unexperienced newborns, made them more vulnerable to predation than other conspecifics. Siberian ibex had the same vigilance level in summer and winter, because of seasonally opposite trade-offs between feeding duration and vigilance level based on seasonal changes in food availability. Individuals in mixed-sex and female groups were more often targeted by predators, prompting individuals from these groups to be more vigilant than in male groups. The vigilance level in males decreased with age likely because of their increased body size and enhanced vigilance experience, which reduced their risk of predation. Our study confirmed that the Siberian ibex' vigilance level inversely correlated with group size, but other various factors, such as forage biomass/quality, sex, biological cycle, group types and age, had significant impacts on their interrelationship.

Evaluating Large-Scale STEM Outreach Efficacy with a Consistent Theme: Thermodynamics for Elementary School Students.

A biannual chemistry demonstration-based show named "Energy and U" was created to extend the general outreach themes of science, technology, engineering, and mathematics (STEM) fields and a college education with a specific goal: to teach the first law of thermodynamics to elementary school students. The effectiveness of the program was analyzed using a clicker survey system for over 12 000 visiting students. The fraction of the students that correctly answered the question "Is it possible to create energy?" increased from 14% immediately before the show to 89% immediately after the show. Students who had seen the show at least 5 months prior were twice as likely to correctly answer at the beginning of the show, demonstrating longer-term lesson retention. Interestingly, similar trends were observed for the adult chaperones that accompanied the students and participated in the clicker survey. A statistically significant difference (>99% confidence interval) was noted between the students' responses to the questions "Can you create energy?" and "Can you destroy energy?", revealing a potential effect of word choice on the interpretation of the first law of thermodynamics despite the two questions representing complementary concepts. Student performance, measured interest in science, and desire to attend college were not correlated with standard economic indicators. This measurement is consistent with the postulate that economic biases surrounding interest in STEM fields are less pronounced in elementary school than later in high school.

Preparation of Viscosity-Sensitive Isoxazoline/Isoxazolyl-Based Molecular Rotors and Directly Linked BODIPY-Fulleroisoxazoline from the Stable meso-(Nitrile Oxide)-Substituted BODIPY.

We developed a simple methodology for the preparation of stable meso-(nitrile oxide)-substituted BODIPYs, which were characterized by spectroscopic methods and X-ray crystallography. These compounds were used for the preparation of isoxazoline- or isoxazolyl-BODIPYs by 1,3-dipolar cycloaddition reaction with dipolarophiles. Several BODIPYs possess molecular rotor behavior, including viscosity-dependent fluorescence. Transient absorption spectroscopy and time-resolved fluorescence are indicative of a 3 orders of magnitude difference in the excited-state lifetime for dichloromethane and glycerol solutions.

Synthesis, Characterization, and Electron-Transfer Properties of Ferrocene-BODIPY-Fullerene Near-Infrared-Absorbing Triads: Are Catecholopyrrolidine-Linked Fullerenes a Good Architecture to Facilitate Electron-Transfer?

A series of covalent ferrocene-BODIPY-fullerene triads with the ferrocene groups conjugated to the BODIPY π-system and the fullerene acceptor linked at the boron hub by a common catecholpyrrolidine bridge were prepared and characterized by 1D and 2D NMR, UV/Vis, steady-state fluorescence spectroscopy, high-resolution mass spectrometry, and, for one of the derivatives, X-ray crystallography. Redox processes of the new compounds were investigated by electrochemical (CV and DPV) methods and spectroelectrochemistry. DFT calculations indicate that the HOMO in all triads was delocalized between ferrocene and BODIPY π-system, the LUMO was always fullerene-centered, and the catechol-centered occupied orbital was close in energy to the HOMO. TDDFT calculations were indicative of the low-energy, low-intensity charge-transfer bands originated from the ferrocene-BODIPY core to fullerene excitation, which explained the similarity of the UV/Vis spectra of the ferrocene-BODIPY dyads and ferrocene-BODIPY-fullerene triads. Photophysical properties of the new triads as well as reference BODIPY-fullerene and ferrocene-BODIPY dyads were investigated by pump-probe spectroscopy in the UV/Vis and NIR spectral regions following selective excitation of the BODIPY-based antenna. Initial charge transfer from the ferrocene to the BODIPY core was shown to outcompete sub-100 fs deactivation of the excited state mediated by the catechol bridge. However, no subsequent electron transfer to the fullerene acceptor was observed. The initial charge separated state relaxes by recombination with a time constant of 150-380 ps.

Effect of extending conjugation via thiophene-based oligomers on the excited state electron transfer rates to ZnO nanocrystals.

Oligothiophene dyes with two to five thiophene units were anchored to oleate-capped, quantum-confined zinc oxide nanocrystals (ZnO NCs) through a cyanoacrylate functional group. While the fluorescence of the bithiophene derivative was too weak for meaningful quenching studies, the fluorescence of the dyes with three, four and five thiophene rings was quenched upon binding to the NCs. Ultrafast pump-probe spectroscopy was used to observe the singlet excited states of the free dyes dissolved in dichloromethane as well as attached to a ZnO NC dispersed in the same solvent. When the dyes were bound to ZnO NCs, ultrafast spectroscopic measurements revealed rapid disappearance of the singlet excited state and appearance of a new transient absorption at higher energy that was assigned to the oxidized dye based on the similar absorption observed upon oxidation of the dye using nitrosonium ion. The appearance lifetimes of the oxidized dyes were assigned to the excited state electron transfer and were 36 ± 2, 22.3 ± 3.9, 26.5 ± 1.5 and 19.4 ± 0.8 ps for bi-, ter-, quarter- and quinquethiophene dyes respectively. Two factors contributed to the similarity in the electron transfer lifetime. First the excited state energies of the dyes were similar, and second, the free energy for electron transfer reaction was sufficiently large to move the event into the energy-independent regime.

Rapid Excited-State Deactivation of BODIPY Derivatives by a Boron-Bound Catechol.

The excited-state dynamics and energetics of a series of BODIPY-derived chromophores bound to a catechol at the boron position were investigated with a combination of static and time-resolved spectroscopy, electrochemistry, and density functional theory calculations. Compared with the difluoro-BODIPY-derived parent compounds, the addition of the catechol at the boron reduced the excited-state lifetime by three orders of magnitude. Deactivation of the excited state proceeded through an intermediate charge-transfer state accessed from the initial optically excited π* state in <1 ps. Despite differences in the structures of the BODIPY derivatives and absorption maxima that spanned the visible portion of the spectrum, all compounds exhibited the same, rapid, excited-state deactivation mechanism, suggesting the generality of the observed dynamics within this class of compounds.

Diabetes is associated with an increased risk of cardiovascular disease in patients with familial hypercholesterolemia.

BACKGROUND: Familial hypercholesterolemia (FH) is the most common genetic disorder of lipoprotein metabolism, affecting 1:250 individuals worldwide. This monogenic disease is associated with lifelong elevation in circulating low-density lipoprotein cholesterol and premature cardiovascular disease (CVD). In 2016, the estimated prevalence of diabetes in Canada was 9%. In the FH population, little is known about the prevalence of diabetes and its impact on CVD risk. OBJECTIVE: The objectives of this study were to investigate the prevalence of diabetes among a large cohort of FH patients and to investigate the association between diabetes and CVD risk. METHODS: The FH Canada registry contains data on 3740 subjects. We selected adult patients with FH according to the Dutch Lipid Clinic Network criteria. After excluding subjects with missing data, there remained 1412 patients who were included in the final analysis. RESULTS: The present cohort from the FH Canada database comprises a total of 73 diabetic patients (5%). The prevalence of CVD was higher in diabetic FH patients (45%) than in nondiabetics (22%) (odds ratio 2.9, 95% confidence interval 1.8-4.7, P < .0001). However, the average Montreal-FH-SCORE was also higher in the diabetic group than in the nondiabetic group (29.7 vs 21.2, respectively, P < .0001). Diabetes was no longer a significant predictor of CVD when the analysis was adjusted for the Montreal-FH-SCORE. CONCLUSION: In conclusion, diabetic FH patients represent a high-risk group for CVD risk, most likely due to the fact that diabetic subjects have many concomitant cardiometabolic risk factors.