Novel role of NCoR1 in impairing spatial memory through the mediation of a novel interacting protein DEC2.

Long-term memory formation requires de novo RNA and protein synthesis. Using differential display PCR, we found that the NCoR1 cDNA fragment is differentially expressed between fast learners and slow learners, with fast learners showing a lower expression level than slow learners in the water maze learning task. Fast learners also show lower NCoR1 mRNA and protein expression levels. In addition, spatial training decreases both NCoR1 mRNA and protein expression, whereas NCoR1 conditional knockout (cKO) mice show enhanced spatial memory. In studying the molecular mechanism, we found that spatial training decreases the association between NCoR1 and DEC2. Both NCoR1 and DEC2 suppress the expression of BDNF, integrin α3 and SGK1 through C/EBPα binding to their DNA promoters, but overexpression of DEC2 in NCoR1 cKO mice rescues the decreased expression of these proteins compared with NCoR1 loxP mice overexpressing DEC2. Further, spatial training decreases DEC2 expression. Spatial training also enhances C/EBPα binding to Bdnf, Itga3 and Sgk1 promoters, an effect also observed in fast learners, and both NCoR1 and DEC2 control C/EBPα activity. Whereas knockdown of BDNF, integrin α3 or SGK1 expression impairs spatial learning and memory, it does not affect Y-maze performance, suggesting that BDNF, integrin α3 and SGK1 are involved in long-term memory formation, but not short-term memory formation. Moreover, NCoR1 expression is regulated by the JNK/c-Jun signaling pathway. Collectively, our findings identify DEC2 as a novel interacting protein of NCoR1 and elucidate the novel roles and mechanisms of NCoR1 and DEC2 in negative regulation of spatial memory formation.

Identification of Ndfip1 as a novel negative regulator for spatial memory formation associated with increased ubiquitination of Beclin 1 and PTEN.

Long-term memory formation requires de novo RNA and protein synthesis. By using the differential display-polymerase chain reaction strategy, we have presently identified the Nedd4 family interacting protein 1 (Ndfip1) cDNA fragment that is differentially expressed between the slow learners and the fast learners from the water maze learning task in rats. Further, the fast learners show decreased Ndfip1 mRNA and protein expression levels than the slow learners. Spatial training similarly decreases the Ndfip1 mRNA and protein expression levels. Conversely, the Ndfip1 conditional heterozygous (cHet) mice show enhanced spatial memory performance compared to the Ndfip1flox/WT control mice. Result from co-immunoprecipitation experiment indicates that spatial training decreases the association between Ndfip1 and the E3 ubiquitin ligase Nedd4 (Nedd4-1), and we have shown that both Beclin 1 and PTEN are endogenous ubiquitination targets of Nedd4 in the hippocampus. Further, spatial training decreases endogenous Beclin 1 and PTEN ubiquitination, and increases Beclin 1 and PTEN expression in the hippocampus. On the other hand, the Becn1 conditional knockout (cKO) mice and the Pten cKO mice both show impaired spatial learning and memory performance. Moreover, the expression level of Beclin 1 and PTEN is higher in the Ndfip1 cHet mice compared with the Ndfip1flox/WT control mice. Here, we have identified Ndfip1 as a candidate novel negative regulation for spatial memory formation and this is associated with increased ubiquitination of Beclin 1 and PTEN in the hippocampus.

Force Distribution and Estimation for Cooperative Transportation Control on Multiple Unmanned Ground Vehicles.

This article presents an effective design of omnidirectional four-mecanum-wheeled vehicles to transport an object and track a predefined trajectory cooperatively. Furthermore, a novel design of the rotary platform is presented for multiple unmanned ground vehicles (m-UGVs) to load objects and provide better maneuverability in confined spaces during cooperative transportation. The number of unmanned ground vehicles (UGVs) is adjustable according to the object's weight and size in the proposed framework because transportation is accomplished without physical grippers. Moreover, to minimize the complexity in dealing with the interactive force between the object and UGVs, no force/torque sensor is used in the design of the control algorithm. Instead, an adaptive sliding-mode controller is formulated to cope with the dynamic uncertainties and smoothly transport an object along a desired trajectory. Thus, three external force analyses-gradient projection method, adaptive force estimation, and radial basis function neural network force estimation-are proposed for m-UGVs. In addition, the stability and the performance tracking of the m-UGV system in the presence of dynamic uncertainties using the proposed force estimation are investigated by employing the Lyapunov theory. Finally, experiments on cooperative transportation are presented to demonstrate the efficiency and efficacy of the m-UGV system.

Force allocation control for distributed drive electric vehicles under split-friction regions and actuator faults.

The stability and drivability of distributed drive electric vehicles over split-friction regions and with actuator faults are studied in this paper by using control allocation. Under the integrated control architecture of high-, medium-, and low-level controllers, a slip-ratio-based synchronization approach is presented to redistribute the driving force for all the driving wheels. The synchronization of slip ratios on wheels is accomplished by autonomously regulating the distribution parameters in the design of a low-level controller. Therefore, the driving force and moment can be adjusted from the design of the regulator on distribution parameters so that the stability and driving performance are ensured when electric vehicles drive over split-friction regions. Subsequently, the concept of distribution parameters is extended to handle actuator faults in electric vehicles by regulating the driving force via the adjustment of distribution parameters. The proportional fault, additive fault, and motor saturation are considered in this paper by compensating for the loss of driving force from the force allocation approach. Numerical examples using CarSim with MATLAB/Simulink and human/hardware-in-the-loop validations are illustrated to demonstrate the efficacy and performance of the proposed control schemes.

DDPG-Based Adaptive Robust Tracking Control for Aerial Manipulators With Decoupling Approach.

Aerial manipulators have the potential to perform various tasks with high agility and mobility, but the requirement of system parameters and the complicated dynamic model impede the implementation in practice. To deal with uncertain parameters and complexity of the coupled dynamic model, a decoupling approach is presented in this article by utilizing the adaptive/robust techniques and reinforcement learning approach for the tracking control of quadrotors with position control on the robotic arm. A reinforcement learning approach is proposed to control the robotic arm ensuring minimal effect on the quadrotor dynamics while following the desired trajectory. With the design of nominal inputs, the dynamic uncertainties from the quadrotor, robotic arm, and payload are coped with by utilizing the proposed adaptive algorithms. In addition, the residue of interactive force/torque after the use of DDPG is compensated by robust controllers so that the stability and tracking performance are guaranteed. Numerical examples and experiments are illustrated to demonstrate the efficacy of the presented aerial manipulator control structure and algorithms.

Melatonin Induction of APP Intracellular Domain 50 SUMOylation Alleviates AD through Enhanced Transcriptional Activation and Aß Degradation.

The amyloid precursor protein (APP) intracellular domain (AICD) is implicated in the pathogenesis of Alzheimer's disease (AD), but post-translational modification of AICD has rarely been studied and its role in AD is unknown. In this study, we examined the role and molecular mechanism of AICD SUMOylation in the pathogenesis of AD. We found that AICD is SUMO-modified by the SUMO E3 ligase protein inhibitor of activated STAT1 (PIAS1) in the hippocampus at Lys-43 predominantly, and that knockdown of PIAS1 decreases endogenous AICD SUMOylation. AICD SUMOylation increases AICD association with its binding protein Fe65 and increases AICD nuclear translocation. Furthermore, AICD SUMOylation increases AICD association with cyclic AMP-responsive element binding protein (CREB) and p65 and their DNA binding for transcriptional activation of neprilysin (NEP) and transthyretin (TTR), two major Aß-degrading enzymes, respectively. Consequently, AICD SUMOylation decreases the Aß level, Aß oligomerization, and amyloid plaque deposits. It also rescues spatial memory deficits in APP/PS1 mice. Conversely, blockade of AICD SUMOylation at Lys-43 produces the opposite effects. Melatonin is identified as an endogenous stimulus that induces AICD SUMOylation. It also decreases the Aß level and rescues reduction of PIAS1, NEP, and TTR expression in APP/PS1 mice. In this study, we demonstrate that AICD SUMOylation functions as a novel endogenous defense mechanism to combat AD.

Restoring Wnt6 signaling ameliorates behavioral deficits in MeCP2 T158A mouse model of Rett syndrome.

The methyl-CpG-binding protein 2 gene, MECP2, is an X chromosome-linked gene encoding the MeCP2 protein, and mutations of MECP2 cause Rett syndrome (RTT). Previous study has shown that re-expression of SUMO-modified MeCP2 in Mecp2-null neurons rescues synaptic and behavioral deficits in Mecp2 conditional knockout mice, whereas about 12-fold decrease in Wnt6 mRNA level was found in MeCP2K412R sumo-mutant mice. Here, we examined the role of Wnt6 in MeCP2 T158A mouse model of RTT. Results show that lentiviral delivery of Wnt6 to the amygdala ameliorates locomotor impairment and social behavioral deficits in these animals. MeCP2 T158A mice show decreased level of GSK-3ß phosphorylation and increased level of ß-catenin phosphorylation. They also show reduced level of MeCP2 SUMOylation. These alterations were also restored by lenti-Wnt6 transduction. Further, both BDNF and IGF-1 expressions are decreased in MeCP2 T158A mice. Overexpression of Wnt6 increases Bdnf and Igf-1 promoter activity in HEK293T cells in a dose-dependent manner. Lenti-Wnt6 transduction to the amygdala similarly increases the mRNA level and protein expression of BDNF and IGF-1 in MeCP2 T158A mice. Moreover, environmental enrichment (EE) similarly ameliorates the locomotor and social behavioral deficits in MeCP2 T158A mice. One of the mechanisms underlying EE is mediated through enhanced MeCP2 SUMOylation and increased Wnt6 expression in these animals by EE.

Ecm29-mediated proteasomal distribution modulates excitatory GABA responses in the developing brain.

Neuronal GABAergic responses switch from excitatory to inhibitory at an early postnatal period in rodents. The timing of this switch is controlled by intracellular Cl- concentrations, but factors determining local levels of cation-chloride cotransporters remain elusive. Here, we report that local abundance of the chloride importer NKCC1 and timely emergence of GABAergic inhibition are modulated by proteasome distribution, which is mediated through interactions of proteasomes with the adaptor Ecm29 and the axon initial segment (AIS) scaffold protein ankyrin G. Mechanistically, both the Ecm29 N-terminal domain and an intact AIS structure are required for transport and tethering of proteasomes in the AIS region. In mice, Ecm29 knockout (KO) in neurons increases the density of NKCC1 protein in the AIS region, a change that positively correlates with a delay in the GABAergic response switch. Phenotypically, Ecm29 KO mice showed increased firing frequency of action potentials at early postnatal ages and were hypersusceptible to chemically induced convulsive seizures. Finally, Ecm29 KO neurons exhibited accelerated AIS developmental positioning, reflecting a perturbed AIS morphological plastic response to hyperexcitability arising from proteasome inhibition, a phenotype rescued by ectopic Ecm29 expression or NKCC1 inhibition. Together, our findings support the idea that neuronal maturation requires regulation of proteasomal distribution controlled by Ecm29.

Sputtering control of Ag2O decoration configurations on ZnO nanorods and their surface arrangement effects on photodegradation ability toward methyl orange.

In this study, a combinational strategy for synthesizing ZnO nanorod arrays interlaced with Ag2O particles was proposed. Hydrothermally derived ZnO nanorod templates were sputter coated with Ag2O particles. The sputtered Ag2O particles can be decorated on the surfaces of the ZnO nanorod arrays with a randomly dispersive or continuous coverage characteristic by controlling the sputtering duration. Structural analysis revealed the formation of satisfactory crystalline ZnO-Ag2O composite nanorods through the hydrothermal and sputtering methods. The ZnO-Ag2O composite nanorods exhibited a significantly enhanced photoactivity compared with that of pristine ZnO nanorods under light irradiation. Moreover, the Ag2O content and the coverage feature of the ZnO-Ag2O composite nanorods influence the photodegradation of methyl orange solution by the composite nanorods under light irradiation. The photodegradation efficiency of the ZnO nanorods was substantially enhanced when the Ag2O particles were decorated on the surfaces in a dispersive manner. This can be attributed to the optimal content of Ag2O particles and their randomly dispersive characteristic on the surface of the composite nanorods, which resulted in the efficient transfer of photocarriers and markedly suppressed the electron-hole recombination rate.

Design of Nanoscaled Surface Morphology of TiO2-Ag2O Composite Nanorods through Sputtering Decoration Process and Their Low-Concentration NO2 Gas-Sensing Behaviors.

TiO2-Ag2O composite nanorods with various Ag2O configurations were synthesized by a two-step process, in which the core TiO2 nanorods were prepared by the hydrothermal method and subsequently the Ag2O crystals were deposited by sputtering deposition. Two types of the TiO2-Ag2O composite nanorods were fabricated; specifically, discrete Ag2O particle-decorated TiO2 composite nanorods and layered Ag2O-encapsulated TiO2 core-shell nanorods were designed by controlling the sputtering duration of the Ag2O. The structural analysis revealed that the TiO2-Ag2O composite nanorods have high crystallinity. Moreover, precise control of the Ag2O sputtering duration realized the dispersive decoration of the Ag2O particles on the surfaces of the TiO2 nanorods. By contrast, aggregation of the massive Ag2O particles occurred with a prolonged Ag2O sputtering duration; this engendered a layered coverage of the Ag2O clusters on the surfaces of the TiO2 nanorods. The TiO2-Ag2O composite nanorods with different Ag2O coverage morphologies were used as chemoresistive sensors for the detection of trace amounts of NO2 gas. The NO2 gas-sensing performances of various TiO2-Ag2O composite nanorods were compared with that of pristine TiO2 nanorods. The underlying mechanisms for the enhanced sensing performance were also discussed.

High-Performance Sample Substrate of Gold Nanoparticle Multilayers for Surface-Assisted Laser Desorption/Ionization Mass Spectrometry.

The development of a sample substrate with superior performance for desorption and ionization of analyte is the key issue to ameliorate the quality of mass spectra for measurements of small molecules in surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). Herein, the homogeneous sample substrate of gold nanoparticle multilayers (AuNPs-ML) with hexagonal lattice was successfully prepared by self-assembly technique. With strong surface plasmon resonance absorption and superior photothermal effect, the sample substrate of AuNPs-ML exhibited high signal sensitivity and low background noise for the detection of model analyte of glucose without additional matrixes in SALDI-MS. Furthermore, compared to merchant matrixes of α-cyano-4-hydroxycinnamic acid (CHCA) and 2,5-dihydroxybenzoic acid (DHB), the sample substrate of AuNPs-ML was demonstrated to ameliorate the quality of mass spectra, including signal strength, background interference and signal/noise (S/N) ratio. The sucrose and tryptophan were also measured to show the extensive applications of AuNPs-ML sample substrate for the detections of small molecules in SALDI-MS. Most importantly, the remarkable reproducibility of glucose mass spectra with relative signal of 7.3% was obtained by the use of AuNPs-ML sample substrate for SALDI-MS. The homogeneous sample substrate of AuNPs-ML greatly improved the quality of mass spectra because of its strong absorption of laser energy, low specific heat, high heat conductivity and extraordinary homogeneity. We believe that AuNPs-ML could be a practical sample substrate for small molecule detection in SALDI-MS.

Microstructures and Photodegradation Performance toward Methylene Orange of Sputtering-Assisted Decoration of ZnFe2O4 Crystallites onto TiO2 Nanorods.

In this study, TiO2⁻ZnFe2O4 (ZFO) core-shell nanorods with various ZFO crystallite thicknesses were synthesized through sputtering-deposited ZFO thin films onto the surfaces of TiO2 nanorods. By coupling the ZFO narrow bandgap oxide with TiO2, an enhanced photodegradation efficiency of methylene orange under irradiation was achieved. Structural analyses revealed that ZFO crystallites fully covered the surfaces of the TiO2 nanorods. The sputtering-deposited ZFO crystallites on the head region of the composite nanorods were markedly thicker than those covering the lateral region of the composite nanorods. The coverage of ZFO crystallites on the TiO2 nanorods led to an improved light harvesting, a decrease in the hole⁻electron recombination rate, as well as the enhanced photodegradation activity of the TiO2⁻ZFO heterostructures under irradiation. The optimized ZFO thickness on the head region of the composite nanorods was approximately 43 nm on average and that at the lateral region of the composite nanorods was 15 nm, which exhibited superior photodegradation ability to methylene orange and retained a stable photodegradation efficiency of approximately 97% after cycling tests. The results herein demonstrate that sputtering deposition of ZFO crystallite with tunable thickness is a promising approach to designing TiO2⁻ZFO composite nanorods with various ZFO coverage sizes and to adjust their photodegradation ability toward organic dyes.

Passivity-based control framework for task-space bilateral teleoperation with parametric uncertainty over unreliable networks.

Bilateral teleoperation systems developed in joint-space or in task-space without taking into account parameter uncertainties and unreliable communication have limited practical applications. In order to ensure stability, improve tracking performance, and enhance applicability, a novel task-space control framework for bilateral teleoperation with kinematic/dynamic uncertainties and time delays/packet losses is studied. In this paper, we have demonstrated that with the proposed control algorithms, the teleoperation system is stable and position tracking is guaranteed when the system is subjected to parametric uncertainties and communication delays. With the transformation of scattering variables, a packet modulation, called Passivity-Based Packet Modulation (PBPM), is proposed to cope with data losses, incurred in transmission of data over unreliable network. Moreover, numerical simulations and experiments are also presented to validate the efficiency of the developed control framework for task-space bilateral teleoperation.

Lactobacillus acidophilus attenuates Salmonella-induced intestinal inflammation via TGF-ß signaling.

BACKGROUND: Salmonella is a common intestinal pathogen that causes acute and chronic inflammatory response. Probiotics reduce inflammatory cytokine production and serve as beneficial commensal microorganisms in the human gastrointestinal tract. TGF-ß (transforming growth factor ß)/SMAD and NF-κB signaling play important roles in inflammation in intestinal cells. However, the involvement of the signaling in regulating inflammation between Salmonella and probiotics is not fully understood. METHODS: L. acidophilus and prebiotic inulin were used to treat human intestinal Caco-2 cells prior to infection with Salmonella. The cells were harvested to examine the cytokines and MIR21 expression with immunoblotting and real-time PCR. NF-κB and SMAD3/4 reporter vectors were transfected into cells to monitor inflammation and TGF-ß1 signaling, respectively. RESULTS: In this study, we showed that the probiotic L. acidophilus decreased Salmonella-induced NF-κB activation in human intestinal Caco-2 cells. Expression of the inflammatory cytokines, TNF-α and IL-8, in L. acidophilus-pretreated cells was also significantly lower than that in cells infected with Salmonella alone. Moreover, TGF-ß1 and MIR21 expression was elevated in cells pretreated with L. acidophilus or synbiotic, a combination of inulin and L. acidophilus, compared to that in untreated cells or cells infected with S. typhimurium alone. By contrast, expression of SMAD7, a target of MIR21, was accordingly reduced in cells treated with L. acidophilus or synbiotics. Consistent with TGF-ß1/MIR21 and SMAD7 expression, SMAD3/4 transcriptional activity was significantly higher in the cells treated with L. acidophilus or synbiotics. Furthermore, TGF-ß1 antibody antagonized the SMAD3/4 and NF-κB transcriptional activity modulated by L. acidophilus in intestinal cells. CONCLUSION: Our results suggest that the TGF-ß1/MIR21 signaling pathway may be involved in the suppressive effects of L. acidophilus on inflammation caused by S. typhimurium in intestinal Caco-2 cells.

The kinesin-like proteins, KAC1/2, regulate actin dynamics underlying chloroplast light-avoidance in Physcomitrella patens.

In plants, light determines chloroplast position; these organelles show avoidance and accumulation responses in high and low fluence-rate light, respectively. Chloroplast motility in response to light is driven by cytoskeletal elements. The actin cytoskeleton mediates chloroplast photorelocation responses in Arabidopsis thaliana. In contrast, in the moss Physcomitrella patens, both, actin filaments and microtubules can transport chloroplasts. Because of the surprising evidence that two kinesin-like proteins (called KACs) are important for actin-dependent chloroplast photorelocation in vascular plants, we wanted to determine the cytoskeletal system responsible for the function of these proteins in moss. We performed gene-specific silencing using RNA interference in P. patens. We confirmed existing reports using gene knockouts, that PpKAC1 and PpKAC2 are required for chloroplast dispersion under uniform white light conditions, and that the two proteins are functionally equivalent. To address the specific cytoskeletal elements responsible for motility, this loss-of-function approach was combined with cytoskeleton-targeted drug studies. We found that, in P. patens, these KACs mediate the chloroplast light-avoidance response in an actin filament-dependent, rather than a microtubule-dependent manner. Using correlation-decay analysis of cytoskeletal dynamics, we found that PpKAC stabilizes cortical actin filaments, but has no effect on microtubule dynamics.

Isothermal electrically and optically induced phase separation of liquid crystal and poly(N-vinylcarbazole) films.

This paper reports the electro- and photo-isomerization-induced isothermal phase separation of liquid crystals (LCs) and poly(N-vinylcarbazole) (PVK). The proposed phase separation process determines reformed PVK films on substrates to obtain switchable LC light valves. UV illumination induces simultaneous isothermal phase transition of the mixture and dissolution of PVK into the LCs. Phase separation of PVK and LCs occurs by the reversed phase transition via rapid electro-isomerization and slow dark-relaxation. During rapid phase separation, micron-sized LC domains (branch-like PVK structures) are generated to develop stable light scattering; during slow dark-relaxation, a uniform PVK film is obtained, thereby providing stable transparency.

ATG4B promotes colorectal cancer growth independent of autophagic flux.

Autophagy is reported to suppress tumor proliferation, whereas deficiency of autophagy is associated with tumorigenesis. ATG4B is a deubiquitin-like protease that plays dual roles in the core machinery of autophagy; however, little is known about the role of ATG4B on autophagy and proliferation in tumor cells. In this study, we found that ATG4B knockdown induced autophagic flux and reduced CCND1 expression to inhibit G 1/S phase transition of cell cycle in colorectal cancer cell lines, indicating functional dominance of ATG4B on autophagy inhibition and tumor proliferation in cancer cells. Interestingly, based on the genetic and pharmacological ablation of autophagy, the growth arrest induced by silencing ATG4B was independent of autophagic flux. Moreover, dephosphorylation of MTOR was involved in reduced CCND1 expression and G 1/S phase transition in both cells and xenograft tumors with depletion of ATG4B. Furthermore, ATG4B expression was significantly increased in tumor cells of colorectal cancer patients compared with adjacent normal cells. The elevated expression of ATG4B was highly correlated with CCND1 expression, consistently supporting the notion that ATG4B might contribute to MTOR-CCND1 signaling for G 1/S phase transition in colorectal cancer cells. Thus, we report that ATG4B independently plays a role as a positive regulator on tumor proliferation and a negative regulator on autophagy in colorectal cancer cells. These results suggest that ATG4B is a potential biomarker and drug target for cancer therapy.

Hypopigmented interface T-cell dyscrasia: a form of cutaneous T-cell dyscrasia distinct from hypopigmented mycosis fungoides.

Hypopigmentation in cutaneous T-cell lymphoproliferative disease should not always be equated with hypopigmented mycosis fungoides (MF). A form of hypopigmented pre-lymphomatous T-cell dyscrasia falling under the designation of the so-called hypopigmented interface variant of T-cell dyscrasia has recently been proposed. The aim of the present study was to establish hypopigmented interface T-cell dyscrasia as its own entity apart from other T-cell dyscrasias and MF using a patient case series. Twenty four cases of hypopigmented interface T-cell dyscrasia were identified in the dermatopathology database of Weill Medical College of Cornell University. There were 17 females and seven males (mean age, 36 years). In children and adolescents, the patients were most commonly of African American extraction. Truncal photo-protected areas manifesting as large solitary patches or multiple smaller macules were characteristic; disease progression to MF occurred in only one patient. The lesions responded to topical steroids and light therapy. The pathology was defined by a cell poor interface associated with degeneration of keratinocytes and melanocytes, and by lymphocytes whose nuclei showed low-grade cerebriform atypia, and which expressed a significant reduction in CD7 and CD62L expression. In 50% of the cases, the implicated cell type was of the CD8 subset. Clonality was not identified. Hypopigmented interface T-cell dyscrasia is a distinct entity separate from and rarely progressive to MF.

Photo- and electro-isomerization of azobenzenes based on polymer-dispersed liquid crystals doped with azobenzenes and their applications.

We report the photo-isomerization and electro-isomerization effects in azobenzenes-doped polymer-dispersed liquid crystals during the switching of the liquid crystal (LC) device between transparent (cis-isomers dominant) and scattering states (trans-isomers dominant). The isothermal phase transition, which is a result of the illumination of UV light and the application of DC voltage, was the main mechanism to switch the LC device between transparency, scattering, and gray scales. This study discusses in detail the variations in the population of cis-isomers as functions of the period and the amplitude of the applied DC voltage.

Drug-induced photoallergic and phototoxic reactions - an update.

INTRODUCTION: Photoallergic and phototoxic medications continue to be an important concern for dermatologists. In the last 5 years, the list of phototoxic and photoallergic medications has expanded, as well as the testing tools used to screen for potential allergy. Currently available testing methods include the photoprick, photoscratch and illuminated intracutaneous tests. If the causative photosensitizer is not the test substance but a metabolite of the test substance, a systemic photoprovocation test can be utilized. Photodynamic therapy pro-photosensitizers have been shown to be sensitizers to visible light, while most other phototoxins respond to the UVA and/or UVB spectrum. AREAS COVERED: This article reviews the findings of a PubMed search for the key words 'photosensitivity', 'photosensitive', 'phototoxicity', 'phototoxic', 'photoallergy' and 'photoallergic'. Articles published over the last 5 years were compared with those published earlier than this to find updated information on photo-reactions. EXPERT OPINION: With the variety of new monoclonal antibodies, clinicians must remain up to date as to the drugs that can cause photo-reactions. There are new tests that can aid in assessing photo-reactions.