High-performance FRET biosensors for single-cell and in vivo lead detection

Forms of lead (Pb) have been insidiously invading human life for thousands of years without obvious signs of their considerable danger to human health. Blood lead level (BLL) is the routine measure used for diagnosing the degree of lead intoxication, although it is unclear whether there is any safe range of BLL. To develop a practical detection tool for living organisms, we engineered a genetically encoded fluorescence resonance energy transfer (FRET)-based Pb²⁺ biosensor, 'Met-lead 1.44 M1', with excellent performance. Met-lead 1.44 M1 has an apparent dissociation constant (K_d) of 25.97 nM, a detection limit (LOD) of 10 nM (2.0 ppb/0.2 μg/dL), and an enhancement dynamic ratio of nearly ~ 5-fold upon Pb²⁺ binding. The 10 nM sensitivity of Met-lead 1.44 M1 is five times below the World Health Organization-permitted level of lead in tap water (10 ppb; WHO, 2017), and fifteen times lower than the maximum BLL for children (3 μg/dL). We deployed Met-lead 1.44 M1 to measure Pb²⁺ concentrations in different living models, including two general human cell lines and one specific line, induced pluripotent stem cell (iPSC)-derived cardiomyocytes, as well as in widely used model species in plant (Arabidopsis thaliana) and animal (Drosophila melanogaster) research. Our results suggest that this new biosensor is suitable for lead toxicological research in vitro and in vivo, and will pave the way toward potential applications for both low BLL measures and rapid detection of environmental lead in its divalent form.

Tacrolimus-Induced Apoptosis is Mediated by Endoplasmic Reticulum-derived Calcium-dependent Caspases-3,-12 in Jurkat Cells

Apoptotic signal pathways are delivered to caspase-3, caspase-9, or both in different cells via the death receptor pathway, mitochondrial pathway, or by the endoplasmic reticulum (ER) pathway through initiators of caspase-3, -8, -9, or -12. Tacrolimus (Tac)-induced apoptosis was characterized by nuclear fragmentation and caspase-3 activation. We examined the effect of tacrolimus on ER-derived calcium and caspase-3,-12-mediated apoptosis on Jurkat human T lymphocyte. Tac decreased the viability of Jurkat cells in a dose-dependent manner. Tac also increased continuously intracellular concentration of calcium from 24 hours to 72 hours. We did not find intracellular calcium changes on the treatment of calcium ionorpore (A23187) regardless of 1 nmol/L Tac concentration level. However, calcium adenosine triphosphatase inhibitor (thapsigargin) increased intracellular calcium accumulation and co-treating 1 nmol/L Tac further induced intracellular calcium accumulation. Interestingly, we found that 1 nmol/L Tac treatment induced activation of caspase-12 protease as well as the catalytic activity of caspase-3 but not catalytic activation of caspase-6, -8, and -9 proteases in Jurkat cells. These data advance our understanding of Tac-induced apoptosis is ER-derived calcium and caspases-3,-12- mediated apoptosis in human Jurkat cell line.

Energy-Efficient Hydrogen Evolution by Fe-S Electrocatalysts: Mechanistic Investigations

The intrinsic catalytic property of a Fe-S complex toward H₂ evolution was investigated in a wide range of acids. The title complex exhibited catalytic events at -1.16 and -1.57 V (vs Fc⁺/Fc) in the presence of trifluoromethanesulfonic acid (HOTf) and trifluoroacetic acid (TFA), respectively. The processes corresponded to the single reduction of the Fe-hydride-S-proton and Fe-hydride species, respectively. When anilinium acid was used, the catalysis occurred at -1.16 V, identical with the working potential of the HOTf catalysis, although the employment of anilinium acid was only capable of achieving the Fe-hydride state on the basis of the spectral and calculated results. The thermodynamics and kinetics of individual steps of the catalysis were analyzed by density functional theory (DFT) calculations and electroanalytical simulations. The stepwise CCE or CE (C, chemical; E, electrochemical) mechanism was operative from the HOTf or TFA source, respectively. In contrast, the involvement of anilinium acid most likely initiated a proton-coupled electron transfer (PCET) pathway that avoided the disfavored intermediate after the initial protonation. Via the PCET pathway, the heterogeneous electron transfer rate was increased and the overpotential was decreased by 0.4 V in comparison with the stepwise pathways. The results showed that the PCET-involved catalysis exhibited substantial kinetic and thermodynamic advantages in comparison to the stepwise pathway; thus, an efficient catalytic system for proton reduction was established.

Synchrotron-Based Infrared Microanalysis of Biological Redox Processes under Electrochemical Control

We describe a method for addressing redox enzymes adsorbed on a carbon electrode using synchrotron infrared microspectroscopy combined with protein film electrochemistry. Redox enzymes have high turnover frequencies, typically 10-1000 s(-1), and therefore, fast experimental triggers are needed in order to study subturnover kinetics and identify the involvement of transient species important to their catalytic mechanism. In an electrochemical experiment, this equates to the use of microelectrodes to lower the electrochemical cell constant and enable changes in potential to be applied very rapidly. We use a biological cofactor, flavin mononucleotide, to demonstrate the power of synchrotron infrared microspectroscopy relative to conventional infrared methods and show that vibrational spectra with good signal-to-noise ratios can be collected for adsorbed species with low surface coverages on microelectrodes with a geometric area of 25 × 25 μm(2). We then demonstrate the applicability of synchrotron infrared microspectroscopy to adsorbed proteins by reporting potential-induced changes in the flavin mononucleotide active site of a flavoenzyme. The method we describe will allow time-resolved spectroscopic studies of chemical and structural changes at redox sites within a variety of proteins under precise electrochemical control.

Heteroleptic Ir(III) complexes containing both azolate chromophoric chelate and diphenylphosphinoaryl cyclometalates; reactivities, electronic properties and applications

The synthesis of a new family of octahedral Ir(III) complexes with dual cyclometalating phosphine chelates, namely: 1-(diphenylphosphino)naphthalene (dpnaH) and isoquinoline (dppiH), is reported. Two series of intermediate complexes, [Ir(dpna)(tht)(2)Cl(2)] (1), [Ir(dpna)(2)(OAc)] (2), [Ir(dppiH)(dppi)Cl(2)] (3) and [Ir(dppi)(2)(OAc)] (4), which can be classified by the coexistence of either a pair of cis-chlorides or a single acetate chelate, were obtained from treatment of phosphine with [IrCl(3)(tht)(3)] (tht = tetrahydrothiophene). The in situ generated acetate complexes 2 and 4 could react with azolate chelates, namely: 5-(2-pyridyl)-3-trifluoromethyl pyrazole (fppzH) and 5-(1-isoquinolyl)-3-tert-butyl-1,2,4-triazole (iqbtzH), to afford a new series of luminescent complexes [Ir(dpna)(2)(fppz)] (5a and 5b), [Ir(dpna)(2)(iqbtz)] (6a and 6b), [Ir(dppi)(2)(fppz)] (7a) and [Ir(dppi)(2)(iqbtz)] (8a). The phosphorescence lifetime (τ(obs)) fell in the range of a few tens of μs, showing possession of excessive ligand-centered ππ* mixed in part with MLCT character. A density functional theory (DFT) study was also conducted in order to shed light on the origin of the transitions in the absorption and emission spectra and to predict emission energies for these complexes. Organic light emitting diodes (OLEDs) displaying bright orange emission and with maximum η(ext) up to 17.1% were fabricated employing complexes 6a and 8a as the phosphorescent dopants.

New series of ruthenium(II) and osmium(II) complexes showing solid-state phosphorescence in far-visible and near-infrared

A new Ru(II) complex, [Ru(fpbpymH)(2)]Cl(2) (1), in which fpbpymH = [5-(trifluoromethyl)pyrazol-3-yl](2,2'-bipyrid-6-yl)methane, was prepared by the treatment of [Ru(DMSO)(4)Cl(2)] with 2 equiv of the terdentate chelate fpbpymH in refluxing ethanol. A single-crystal X-ray diffraction study of 1 revealed a distorted octahedral Ru(II) framework, showing strong N-H...Cl hydrogen bonding between the fpbpymH ligand and Cl anions. In the presence of Na(2)CO(3), the methylene linkers of chelates in 1 underwent stepwise oxygenation, forming the charge-neutral complexes [Ru(fpbpym)(fpbpyk)] (2) and [Ru(fpbpyk)(2)] (3) [fpbpykH = [5-(trifluoromethyl)pyrazol-3-yl](2,2'-bipyrid-6-yl) ketone] in sequence. The respective charge-neutral Os(II) complex [Os(fpbpyk)(2)] (4) was also isolated by the treatment of OsCl(3).3H(2)O with 2 equiv of the terdentate chelate fpbpymH. Electrochemical analysis indicated that the introduction of the electron-withdrawing ketone group in 2-4 increased the metal-based oxidation potential in sequence. For the photophysical properties, complexes 1-4 are essentially nonluminescent in solution (e.g., CH(2)Cl(2) or MeOH) at room temperature, but all exhibit 600-1100 nm phosphorescence with moderate intensity for the powdery, solid sample at room temperature. The trend in terms of the emission peak wavelength of 1 (666 nm) < 3 (795 nm) < 2 (810 nm) < 4 (994 nm) among titled complexes is in agreement with the corresponding onset of absorption spectra as well as the time-dependent density functional theory calculation of 1 < 3 < 2 < 4.

Authentic-blue phosphorescent iridium(III) complexes bearing both hydride and benzyl diphenylphosphine; control of the emission efficiency by ligand coordination geometry

Sequential treatment of IrCl(3) x nH(2)O with 2 equiv of benzyl diphenylphosphine (bdpH) and then 1 equiv of 3-trifluoromethyl-5-(2-pyridyl) pyrazole (fppzH) in 2-methoxyethanol gave formation to three isomeric complexes with formula [Ir(bdp)(fppz)(bdpH)H] (1-3). Their molecular structures were established by single crystal X-ray diffraction studies, showing existence of one monodentate phosphine bdpH, one terminal hydride, a cyclometalated bdp chelate, and a fppz chelate. Variation of the metal-ligand bond distances showed good agreement with those predicted by the trans effect. Raman spectroscopic analyses and the corresponding photophysical data are also recorded and compared. Among all isomers complex 1 showed the worst emission efficiency, while complexes 2 and 3 exhibited the greatest luminescent efficiency in solid state and in degassed CH(2)Cl(2) solution at room temperature, respectively. This structural relationship could be due to the simultaneously weakened hydride and the monodentate bdpH bonding that are destabilized by the trans-pyrazolate anion and cyclometalated benzyl group, respectively.

Lack of association between ACE and bradykinin B2 receptor gene polymorphisms and ACE inhibitor-induced coughing in hypertensive Koreans

BACKGROUND & OBJECTIVE

Angiotensin converting enzyme (ACE) inhibitors are used widely in therapy for hypertension, congestive heart failure and myocardial infarction. However, coughing, one of their major adverse effects limits their use. It is documented that Asians are more liable to coughing than Europeans. The aim of this study was to investigate genetic polymorphism involved in ACE inhibitor-induced coughing.

METHODS

We monitored hypertensive subjects (n = 110) treated with ACE inhibitors, and tested for any associations between ACE inhibitor-induced coughing and polymorphisms in the genes for ACE and the bradykinin B2 receptor, which are suspected to be related to coughing.

RESULTS & DISCUSSION

We found no significant differences between the groups with coughing and without coughing in the frequency of ACE I/D (Insertion/Deletion) polymorphisms. One single nucleotide polymorphism was discovered in the promoter (-58T/C) and, one in intron-exon junction upsteam of exon 2 (-59C/A), of the bradykinin B2 receptor gene. However, no significant correlation was found between those genotypes or allele distributions and ACE inhibitor-induced coughing.

CONCLUSION

We found no significant links between polymorphisms of the ACE gene or bradykinin B2 receptor gene with ACE inhibitor-induced coughing in hypertensive Koreans. But, the topic remains controversial and requires more study.

Emergent patterns of feedback strategies in performing a closed motor skill

This sturdy identified self-chosen patterns of feedback usage and how they influenced accuracy and consistency in performing a closed motor skill. Learners completed 100 practice trials with 25 opportunities to receive knowledge of results (KR), the timing of which was self-chosen, followed by 25 no KR retention trials. The study identified two patterns of self-chosen KR, namely, a faded frequency pattern and a reversed faded frequency pattern. Analyses of variance indicated a significant trial block effect for accuracy in acquisition and no significant main effects or interactions associated with self-chosen patterns of KR. Quantification of regularity of KR patterns yielded correlations indicating that less regularity was associated with greater accuracy in performing the task. These results were congruent with previous research on self chosen feedback.

Modulation of NMDA receptor subunit mRNA in butorphanol-tolerant and -withdrawing rats

The NMDA receptor has been implicated in opioid tolerance and withdrawal. The effects of continuous infusion of butorphanol on the modulation of NMDA receptor subunit NR1, NR2A, NR2B, and NR2C gene expression were investigated by using in situ hybridization technique. Continuous intracerebroventricular (i.c.v.) infusion with butorphanol (26 nmol/microl/h) resulted in significant modulations in the NRI, NR2A, and NR2B mRNA levels. The level of NR1 mRNA was significantly decreased in the cerebral cortex, thalamus, and CA1 area of hippocampus in butorphanol tolerant and withdrawal (7 h after stopping the infusion) rats. The NR2A mRNA was significantly decreased in the CA1 and CA3 of hippocampus in tolerant rats and increased in the cerebral cortex and dentate gyrus in butorphanol withdrawal rats. NR2B subunit mRNA was decreased in the cerebral cortex, caudate putamen, thalamus, CA3 of hippocampus in butorphanol withdrawal rats. No changes of NR1, NR2A, NR2C subunit mRNA in the cerebellar granule cell layer were observed in either butorphanol tolerant or withdrawal rats. Using quantitative ligand autoradiography, the binding of NMDA receptor ligand [3H]MK-801 was increased significantly in all brain regions except in the thalamus and hippocampus, at the 7 hr after stopping the butorphanol infusion. These results suggest that region-specific changes of NMDA receptor subunit mRNA (NR1 and NR2) as well as NMDA receptor binding ([3H]MK-801) are involved in the development of tolerance to and withdrawal from butorphanol.

Protective effects of bergenin, the major constituent of Mallotus japonicus, on D-galactosamine-intoxicated rat hepatocytes

This study was designed to investigate the effects of bergenin against D-galactosamine-induced injury in primary cultured rat hepatocytes. Bergenin (100 microM) decreased the release of glutamic pyruvic transaminase and sorbitol dehydrogenase by 62 and 50%, respectively, into hepatocyte medium incubated for 14 h with 1.5 mM galactosamine. Decreased RNA synthesis by 1.5 mM galactosamine was recovered 2.5 times compared with that of control hepatocytes at 100 microM bergenin. Therefore, the present results suggest that bergenin show hepatoprotective effects against galactosamine-intoxicated rat hepatocytes by inhibiting the release of glutamic pyruvic transaminase and sorbitol dehydrogenase as well as by increasing RNA synthesis.

Effect of low back posture on the morphology of the spinal canal

OBJECTIVE

To define the possible mechanism of posture-dependent symptoms of spinal stenosis by measuring the effect of low back posture on morphologic changes of the intervertebral discs and spinal canal in healthy young people.

DESIGN

Twenty healthy young volunteers underwent magnetic resonance imaging while supine with their spine in neutral, flexed, extended, and right and left rotational positions. The axial MR images at the middle of the intervertebral discs of L3-4 and L4-5 were analyzed to measure the difference in the size and shape of the intervertebral discs and spinal canal in each posture.

RESULTS

Extension or rotation decreased the sagittal diameters and cross-sectional areas of the dural sac and spinal canal and increased the thickness of the ligamentum flavum, whereas flexion had the opposite effects. The gap between the convex posterior disc margin and the anterior margin of the facet joint on each side, represented as the subarticular sagittal diameter, increased with flexion and decreased with extension or rotation. The direction of rotation did not result in asymmetry of the subarticular sagittal diameter, but right rotation caused thickening of the right ligamentum flavum, and vice versa. The shape and dimensions of the disc did not change significantly according to the positions of the low back.

CONCLUSIONS

With extension or rotation, the thickness of the ligamentum flavum increased and the posterior margin of the intervertebral disc was approximated to the facet joint without any change in shape and size of the disc. These phenomena result in a decrease in the size of the spinal canal and dural sac in extension or rotation postures in young healthy people without disc degeneration, and may explain the posture-dependent symptom of spinal stenosis.

Anti-inflammatory effects of fangchinoline and tetrandrine

Fangchinoline and tetrandrine are the major alkaloids from Stephania tetrandrae S. Moore which has been used traditionally for the treatment of inflammatory diseases in oriental countries including Korea. Both fangchinoline and tetrandrine showed anti-inflammatory effects on mouse ear edema induced by croton oil. In addition, the effects of fangchinoline and tetrandrine on cyclooxygenase, murine interleukin-5 (mIL-5) and human interleukin-6 (hIL-6) were examined in vitro to investigate the anti-inflammatory action mechanisms. One hundred micromolar of fangchinoline showed 35% of inhibition on cyclooxygenase, but the same concentration of tetrandrine did not show any inhibition. On the other hand, 12.5 microM of tetrandrine exhibited 95% of inhibition on mIL-5 activity, while fangchinoline did not show any effects. However, 4 microM of fangchinoline and 6 microM of tetrandrine showed 63 and 86% of inhibitions on hIL-6 activity, respectively. These results suggest that biochemical mechanisms of fangchinoline and tetrandrine on anti-inflammation are significantly different even though they are similar in chemical structure.

Antihepatotoxic activity of bergenin, the major constituent of Mallotus japonicus, on carbon tetrachloride-intoxicated hepatocytes

To determine the antihepatotoxic activity of bergenin from Mallotus japonicus, carbon tetrachloride (CCl4)-induced cytotoxicity in primary cultured rat hepatocytes has been adopted as an assay system. Bergenin significantly reduced the activities of glutamic pyruvic transaminase and sorbitol dehydrogenase released from the CCl4-intoxicated hepatocytes. The antihepatotoxicity of bergenin was also evidenced by elevating the activities of glutathione S-transferase and glutathione reductase, and content of glutathione in the CCl4-intoxicated hepatocytes. From these results, it is assumed that bergenin exerted antihepatotoxicity against CCl4-induced cytotoxicity through glutathione-mediated detoxification as well as free radical suppressing activity.

Suloctidil-induced hepatotoxicity

Suloctidil is a new drug that is currently being evaluated in many clinical trials for use in dementia and thrombotic disorders. Hepatotoxicity has to date been reported exclusively in the European literature, and the few available histologic descriptions have been reported in the French language. We report a case of suloctidil-induced hepatotoxicity documented by serum liver biochemical tests and liver biopsy. Histologic features included focal necrosis of hepatocytes, mild hyperplasia of Kupffer cells, and other features suggestive of mild acute hepatitis.

Substance data bases and right to know laws: application to occupational epidemiology

The Illinois Right to Know (RTK) law included requirements for substance lists to be submitted by companies to the Illinois Department of Labor (IDOL). This provided an opportunity to test the feasibility of identifying workplaces utilizing common chemicals for future epidemiologic investigations. A sample of IDOL files (n = 115) was obtained, and relevant data elements were coded. A second sample of substance names within these files (n = 1,015) was selected, and searches in three standard references were conducted to identify chemical descriptions. Equal proportions of employers and manufacturer/suppliers were in general compliance with RTK law reporting requirements (58%). Forty-five percent of substances sampled from employers (chemical users) and 71% of substances sampled from manufacturer/suppliers (chemical producers and distributors) could be identified. The ability to identify substances reported using chemical names was approximately equal across companies (90%), while the ability to identify substances with nonchemical names was greater in manufacturer (59%) than in employer (32%) files. This study suggests that the ability to identify potential occupationally exposed groups using this resource may be greater among manufacturers than among employers. Recognition of substances used in the workplace could be improved if companies were required to report chemical names.