B0-insensitive image navigators for prospective motion-corrected MRS with localized second-order shimming.

PURPOSE: Localized shimming in single-voxel MRS often results in large B0 inhomogeneity outside the volume-of-interest. This causes unacceptable degradation in motion navigator images. Switching back and forth between whole-brain shim and localized shim is possible for linear shims, but not for higher-order shims. Here we propose motion navigators largely insensitive to B0 inhomogeneity for prospective motion-corrected MRS with localized higher-order shimming. METHODS: A recent fast high-resolution motion navigator based on spiral-in/out k-space trajectories and multislice-to-volume registration was modified by splitting the readout into multiple shot interleaves which shortened the echo time and reduced the effect of B0 inhomogeneity. The performance of motion correction was assessed in healthy subjects in the prefrontal cortex using a sLASER sequence at 3T (N = 5) and 7T (N = 5). RESULTS: With multiple spatial interleaves, excellent quality navigator images were acquired in the whole brain in spite of large B0 inhomogeneity outside the MRS voxel. The total duration of the navigator in sLASER remained relatively short even with multiple shots (3T: 10 spatial interleaves 94 ms per slice; 7T: 15 spatial interleaves 103 ms per slice). Prospective motion correction using the multi-shot navigators yielded comparable spectral quality (water linewidth and metabolite SNR) with and without subject motion. CONCLUSION: B0-insensitive motion navigators enable prospective motion correction for MRS with all first- and second-order shims adjusted in the MRS voxel, providing optimal spectral linewidth.

Clinically Meaningful Magnetic Resonance Endpoints Sensitive to Preataxic Spinocerebellar Ataxia Types 1 and 3.

OBJECTIVE: This study was undertaken to identify magnetic resonance (MR) metrics that are most sensitive to early changes in the brain in spinocerebellar ataxia type 1 (SCA1) and type 3 (SCA3) using an advanced multimodal MR imaging (MRI) protocol in the multisite trial setting. METHODS: SCA1 or SCA3 mutation carriers and controls (n = 107) underwent MR scanning in the US-European READISCA study to obtain structural, diffusion MRI, and MR spectroscopy data using an advanced protocol at 3T. Morphometric, microstructural, and neurochemical metrics were analyzed blinded to diagnosis and compared between preataxic SCA (n = 11 SCA1, n = 28 SCA3), ataxic SCA (n = 14 SCA1, n = 37 SCA3), and control (n = 17) groups using nonparametric testing accounting for multiple comparisons. MR metrics that were most sensitive to preataxic abnormalities were identified using receiver operating characteristic (ROC) analyses. RESULTS: Atrophy and microstructural damage in the brainstem and cerebellar peduncles and neurochemical abnormalities in the pons were prominent in both preataxic groups, when patients did not differ from controls clinically. MR metrics were strongly associated with ataxia symptoms, activities of daily living, and estimated ataxia duration. A neurochemical measure was the most sensitive metric to preataxic changes in SCA1 (ROC area under the curve [AUC] = 0.95), and a microstructural metric was the most sensitive metric to preataxic changes in SCA3 (AUC = 0.92). INTERPRETATION: Changes in cerebellar afferent and efferent pathways underlie the earliest symptoms of both SCAs. MR metrics collected with a harmonized advanced protocol in the multisite trial setting allow detection of disease effects in individuals before ataxia onset with potential clinical trial utility for subject stratification. ANN NEUROL 2022.

Plug-and-play advanced magnetic resonance spectroscopy.

PURPOSE: Advanced MRS protocols improve data quality and reproducibility relative to vendor-provided protocols; however, they are challenging to incorporate into the clinical workflow and require local MRS expertise for successful implementation. Here, we developed an automated advanced MRS acquisition protocol at 3T to facilitate acquisition of high-quality spectroscopic data without local MRS expertise. METHODS: First, a B0 shimming protocol was selected for automation by comparing 3 widely used B0 algorithms (2 vendor protocols and FAST(EST)MAP). Next, voxel-based B0 and B1 calibrations were incorporated into the consensus-recommended semi-LASER sequence and combined with an automated VOI prescription tool, a recently developed method for automated voxel prescription. The efficiency of collecting single-voxel data from a clinical cohort (N = 40) with the automated protocol (calibration time and fraction of usable datasets) was compared with the nonautomated semi-LASER protocol (N = 35) whereby all prescan calibrations were executed manually in the academic hospital setting with rotating MR technologists in the neuroradiology unit. RESULTS: A multi-iteration FAST(EST)MAP protocol resulted in narrower water linewidths than vendor's B0 shim protocols for data acquired from 6 brain locations (p < 1e-5) and was selected for automation. The automated B0 and B1 calibrations resulted in a time saving of ~4.5 minutes per voxel relative to the same advanced protocol executed manually. All spectra acquired with the automated protocol were usable, whereas only 86% of those collected with the manual protocol were usable and spectral quality was more variable. CONCLUSION: The plug-and-play advanced MRS protocol allows automated acquisition of high-quality MRS data with high success rate and consistency on a clinical 3T platform.

Analysis of Uncertainties in Inductance of Multi-Layered Printed-Circuit Spiral Coils.

Eddy-current sensors are widely used for precise displacement sensing and non-destructive testing. Application of printed-circuit board (PCB) technology for manufacturing sensor coils may reduce the cost of the sensor and enhance the performance by ensuring consistency. However, these prospects depend on the uniformness of the sensor coil. Inductance measurements of sample coils reveal rather considerable variations. In this paper, we investigate the sources of these variations. Through image analysis of cut-away cross-sections of sensor coils, four factors that contribute to the inductance variations are identified: the distance between layers, the distance between tracings, cross-sectional areas, and misalignment among layers. By using and extending existing method of calculating inductance of spiral coils, the inductance distributions are obtained when these factors are randomly varied. A sensitivity analysis shows that the inductance uncertainty is most affected by the uniformness of the spacings between coil traces and the distances between layers. Improvements in PCB manufacturing process can help to reduce the uncertainty in inductance.

Structural Basis of Redox-Sensing Transcriptional Repressor Rex with Cofactor NAD+ and Operator DNA.

The transcriptional repressor Rex plays important roles in regulating the expression of respiratory genes by sensing the reduction-oxidation (redox) state according to the intracellular NAD+/NADH balance. Previously, we reported on crystal structures of apo, NAD+-bound, and NADH-bound forms of Rex from Thermotoga maritima to analyze the structural basis of transcriptional regulation depending on either NAD+ or NADH binding. In this study, the crystal structure of Rex in ternary complex with NAD+ and operator DNA revealed that the N-terminal domain of Rex, including the helix-turn-helix motif, forms extensive contacts with DNA in addition to DNA sequence specificity. Structural comparison of the Rex in apo, NAD+-bound, NADH-bound, and ternary complex forms provides a comprehensive picture of transcriptional regulation in the Rex. These data demonstrate that the conformational change in Rex when binding with the reduced NADH or oxidized NAD+ determines operator DNA binding. The movement of the N-terminal domains toward the operator DNA was blocked upon binding of NADH ligand molecules. The structural results provide insights into the molecular mechanism of Rex binding with operator DNA and cofactor NAD+/NADH, which is conserved among Rex family repressors. Structural analysis of Rex from T. maritima also supports the previous hypothesis about the NAD+/NADH-specific transcriptional regulation mechanism of Rex homologues.

Calibration-free regional RF shims for MRS.

PURPOSE: Achieving a desired RF transmit field ( B1+ ) in small regions of interest is critical for single-voxel MRS at ultrahigh field. Radio-frequency (RF) shimming, using parallel transmission, requires B1+ mapping and optimization, which limits its ease of use. This work aimed to generate calibration-free RF shims for predefined target regions of interest, which can be applied to any participant, to produce a desired absolute magnitude B1+ (| B1+ |). METHODS: The RF shims were found offline by joint optimization on a database comprising B1+ maps from 11 subjects, considering regions of interest in occipital cortex, hippocampus and posterior cingulate, as well as whole brain. The | B1+ | achieved was compared with a tailored shimming approach, and MR spectra were acquired using tailored and calibration-free shims in 4 participants. Global and local 10g specific-absorption-rate deposition were estimated using Duke and Ella dielectric models. RESULTS: There was no difference in the mean | B1+ | produced using calibration-free versus tailored RF shimming in the occipital cortex (p = .15), hippocampus (p = .5), or posterior cingulate (p = .98), although differences were observed in the RMS error | B1+ |. Spectra acquired using calibration-free shims had similar SNR and low residual water signal. Under identical power settings, specific-absorption-rate deposition was lower compared with operating in quadrature mode. For example, the total head specific absorption rate was around 35% less for the occipital cortex. CONCLUSION: This work demonstrates that static RF shims, optimized offline for small regions, avoid the need for B1+ mapping and optimization for each region of interest and participant. Furthermore, power settings may be increased when using calibration-free shims, to better take advantage of RF shimming.

A bispecific soluble receptor fusion protein that targets TNF-α and IL-21 for synergistic therapy in inflammatory arthritis.

This study was aimed at investigating the therapeutic effects of BITRAP, a bispecific fusion protein targeting TNF-α and IL-21, on the development of autoimmune arthritis in humans and mice. To verify the effects of BITRAP in human, peripheral blood mononuclear cells were cultured with BITRAP under IL-17-producing T (Th17) cell-polarizing conditions or osteoclast differentiation conditions. BITRAP treatment inhibited the production of IL-17 and vascular endothelial growth factor but increased the production of IL-10 in CD4+ T cells, as well as directly suppressed osteoclastogenesis. Collagen-induced arthritis (CIA) and IL-1R antagonist (IL-1Ra) knockout mice were treated with BITRAP. Following injection in CIA mice, BITRAP rapidly migrated into the inflamed joints and remained there for 72 hours. Application of BITRAP attenuated the severity of autoimmune arthritis in CIA and IL-1Ra knockout mice by reducing the numbers of inflammatory cytokine-expressing cells and Th17 cells and antibody secretion. Finally, BITRAP suppressed STAT3 phosphorylation, as well as production of IL-17 and TNF-α, in murine splenic CD4+ T cells. These findings suggest that BITRAP, a bispecific fusion protein targeting TNF-α and IL-21, may be an effective treatment to overcome the limitations of anti-TNF therapy for patients with rheumatoid arthritis.

Evaluation of 8-Channel Radiative Antenna Arrays for Human Head Imaging at 10.5 Tesla.

For human head magnetic resonance imaging at 10.5 tesla (T), we built an 8-channel transceiver dipole antenna array and evaluated the influence of coaxial feed cables. The influence of coaxial feed cables was evaluated in simulation and compared against a physically constructed array in terms of transmit magnetic field (B1+) and specific absorption rate (SAR) efficiency. A substantial drop (23.1% in simulation and 20.7% in experiment) in B1+ efficiency was observed with a tight coaxial feed cable setup. For the investigation of the feed location, the center-fed dipole antenna array was compared to two 8-channel end-fed arrays: monopole and sleeve antenna arrays. The simulation results with a phantom indicate that these arrays achieved ~24% higher SAR efficiency compared to the dipole antenna array. For a human head model, we observed 30.8% lower SAR efficiency with the 8-channel monopole antenna array compared to the phantom. Importantly, our simulation with the human model indicates that the sleeve antenna arrays can achieve 23.8% and 21% higher SAR efficiency compared to the dipole and monopole antenna arrays, respectively. Finally, we obtained high-resolution human cadaver images at 10.5 T with the 8-channel sleeve antenna array.

Structural basis of operator sites recognition and effector binding in the TetR family transcription regulator FadR.

FadR is a fatty acyl-CoA dependent transcription factor that regulates genes encoding proteins involved in fatty-acid degradation and synthesis pathways. In this study, the crystal structures of Bacillus halodurans FadR, which belong to the TetR family, have been determined in three different forms: ligand-bound, ligand-free and DNA-bound at resolutions of 1.75, 2.05 and 2.80 Å, respectively. Structural and functional data showed that B. halodurans FadR was bound to its operator site without fatty acyl-CoAs. Structural comparisons among the three different forms of B. halodurans FadR revealed that the movement of DNA binding domains toward the operator DNA was blocked upon binding of ligand molecules. These findings suggest that the TetR family FadR negatively regulates the genes involved in fatty acid metabolism by binding cooperatively to the operator DNA as a dimer of dimers.

AutoVOI: real-time automatic prescription of volume-of-interest for single voxel spectroscopy.

PURPOSE: To develop a fast and automated volume-of-interest (VOI) prescription pipeline (AutoVOI) for single-voxel MRS that removes the need for manual VOI placement, allows flexible VOI planning in any brain region, and enables high inter- and intra-subject consistency of VOI prescription. METHODS: AutoVOI was designed to transfer pre-defined VOIs from an atlas to the 3D anatomical data of the subject during the scan. The AutoVOI pipeline was optimized for consistency in VOI placement (precision), enhanced coverage of the targeted tissue (accuracy), and fast computation speed. The tool was evaluated against manual VOI placement using existing T1 -weighted data sets and corresponding VOI prescriptions. Finally, it was implemented on 2 scanner platforms to acquire MRS data from clinically relevant VOIs that span the cerebrum, cerebellum, and the brainstem. RESULTS: The AutoVOI pipeline includes skull stripping, non-linear registration of the atlas to the subject's brain, and computation of the VOI coordinates and angulations using a minimum oriented bounding box algorithm. When compared against manual prescription, AutoVOI showed higher intra- and inter-subject spatial consistency, as quantified by generalized Dice coefficients (GDC), lower intra- and inter-subject variability in tissue composition (gray matter, white matter, and cerebrospinal fluid) and higher or equal accuracy, as quantified by GDC of prescribed VOI with targeted tissues. High quality spectra were obtained on Siemens and Philips 3T systems from 6 automatically prescribed VOIs by the tool. CONCLUSION: Robust automatic VOI prescription is feasible and can help facilitate clinical adoption of MRS by avoiding operator dependence of manual selection.

3D Bioprinting for Artificial Pancreas Organ.

Type 1 diabetes mellitus (T1DM) results from an autoimmune destruction of insulin-producing beta cells in the islet of the endocrine pancreas. Although islet transplantation has been regarded as an ideal strategy for T1D, transplanted islets are rejected from host immune system. To immunologically protect them, islet encapsulation technology with biocompatible materials is emerged as an immuno-barrier. However, this technology has been limited for clinical trial such as hypoxia in the central core of islet bead, impurity of islet bead and retrievability from the body. Recently, 3D bioprinting has been emerged as an alternative approach to make the artificial pancreas. It can be used to position live cells in a desired location with real scale of human organ. Furthermore, constructing a vascularization of the artificial pancreas is actualized with 3D bioprinting. Therefore, it is possible to create real pancreas-mimic artificial organ for clinical application. In conclusion, 3D bioprinting can become a new leader in the development of the artificial pancreas to overcome the existed islet.

Short stature is associated with the development of lower limb ischaemia during extracorporeal life support.

BACKGROUND: Percutaneous cannulation of femoral vessels has been widely used for the rapid deployment of extracorporeal life support (ECLS). Limb ischaemia is a devastating complication in patients receiving ECLS. Our aim was to evaluate the predictors of limb ischaemia during ECLS and to determine the role of preventative distal perfusion. METHODS: Two hundred and fifty-five consecutive patients who received veno-arterial ECLS due to cardiac and/or respiratory failure were enrolled from January 2009 to December 2015. All patients received ECLS for more than 6 hours and the data was reviewed retrospectively. Distal perfusion to minimise lower limb ischaemia was performed at the discretion of the physician. Predictors for lower limb ischaemia during ECLS were analysed using multivariate regression analysis. RESULTS: For the 255 patients, the mean age was 58 and 177 (69.4%) were male. Limb ischaemia developed in 24 patients (9.4%); 178 patients (69.8%) died within 30 days. Among the 24 patients, one patient (4.2%) developed limb ischaemia with preventative distal perfusion. Fourteen patients (58.3%) received therapeutic distal perfusion. After distal perfusion, two patients (8.3%) still required surgical intervention. Limb ischaemia was more frequent in female patients (54.2% in the ischaemia group versus 28.1% in the non-ischaemia group, p=0.008) and shorter patients (162.0 ± 9.5 cm in the ischaemia group versus 166.3 ± 9.1 cm in the non-ischaemia group, p=0.027). Patients shorter than 165 cm were more commonly diagnosed with ischaemia compared to those who were taller than 165 cm (79.2% versus 40.7%, p<0.001). In a multivariate regression analysis, height under 165 cm was the only predictor for limb ischaemia (Odds ratio (OR) [95% confidence interval (CI)] = 12.645 [3.190-50.118]). CONCLUSION: Smaller female patients are more prone to developing limb ischaemia from femoral ECLS. Our findings might support preventative distal perfusion and more careful observation of these patients.

Comparison of the Efficacy and Safety of Aripiprazole Versus Bupropion Augmentation in Patients With Major Depressive Disorder Unresponsive to Selective Serotonin Reuptake Inhibitors: A Randomized, Prospective, Open-Label Study.

PURPOSE: The purpose of this study was to compare the efficacy and safety of aripiprazole versus bupropion augmentation in patients with major depressive disorder (MDD) unresponsive to selective serotonin reuptake inhibitors (SSRIs). METHODS: This is the first randomized, prospective, open-label, direct comparison study between aripiprazole and bupropion augmentation. Participants had at least moderately severe depressive symptoms after 4 weeks or more of SSRI treatment. A total of 103 patients were randomized to either aripiprazole (n = 56) or bupropion (n = 47) augmentation for 6 weeks. Concomitant use of psychotropic agents was prohibited. Montgomery Asberg Depression Rating Scale, 17-item Hamilton Depression Rating scale, Iowa Fatigue Scale, Drug-Induced Extrapyramidal Symptoms Scale, Psychotropic-Related Sexual Dysfunction Questionnaire scores were obtained at baseline and after 1, 2, 4, and 6 weeks of treatment. RESULTS: Overall, both treatments significantly improved depressive symptoms without causing serious adverse events. There were no significant differences in the Montgomery Asberg Depression Rating Scale, 17-item Hamilton Depression Rating scale, and Iowa Fatigue Scale scores, and response rates. However, significant differences in remission rates between the 2 groups were evident at week 6 (55.4% vs 34.0%, respectively; P = 0.031), favoring aripiprazole over bupropion. There were no significant differences in adverse sexual events, extrapyramidal symptoms, or akathisia between the 2 groups. CONCLUSIONS: The present study suggests that aripiprazole augmentation is at least comparable to bupropion augmentation in combination with SSRI in terms of efficacy and tolerability in patients with MDD. Both aripiprazole and bupropion could help reduce sexual dysfunction and fatigue in patients with MDD. Aripiprazole and bupropion may offer effective and safe augmentation strategies in patients with MDD who are unresponsive to SSRIs. Double-blinded trials are warranted to confirm the present findings.

Human soluble delta-like 1 homolog exerts antitumor effects in vitro and in vivo.

Proteolysis of delta-like 1 homolog (DLK1), a cell-surface transmembrane protein, produces an active soluble form of DLK1 (sDLK1). Both membrane-bound DLK1 and sDLK1 modulate multiple developmental processes including adipogenesis, osteogenesis, chondrogenesis and myogenesis. However, cancer-related functions of DLK1 have not yet been established. We thus evaluated the roles of extracellular sDLK1, comprising six EGF-like domains and juxtamembrane regions, in human pancreatic cancer MIA PaCa-2 cells in vitro and in vivo. We observed that sDLK1 exerted antitumor effects not only in cancer cell migration and anchorage-independent cell growth but also in in vivo tumor growth.

Fn14-Fc suppresses germinal center formation and pathogenic B cells in a lupus mouse model via inhibition of the TWEAK/Fn14 Pathway.

BACKGROUND: Systemic lupus erythematosus (SLE) is an autoimmune-mediated chronic inflammatory disease. Half of patients with SLE suffer from lupus nephritis, which is major cause of death in SLE. TNF-like weak inducer of apoptosis (TWEAK)/fibroblast growth factor-inducible 14 (Fn14) interactions mediate inflammatory responses that are linked to the pathogenesis of lupus nephritis. Blocking of the TWEAK/Fn14 pathway by Fn14-Fc was performed in a SLE mouse model and the likely therapeutic mechanisms were investigated. METHODS: To investigate the impact of TWEAK on B cell differentiation in SLE, the levels of AID, Blimp-1, and IRF4 messenger RNA were measured in CD19(+) B cells extracted from the spleens of sanroque mice and cultured with TWEAK. To identify the therapeutic effects of Fn14-Fc in SLE, sanroque mice were treated with Fn14-Fc or a control-Fc for 3 weeks. Immunoglobulin (Ig) G, IgG1, IgG2a, and anti-dsDNA antibody (Ab) levels were measured in the sera of each group. Spleens from each group were stained with antibodies against CD4, B220, GL-7, CD138, and PD-1. Kidneys were stained with hematoxylin and eosin (H&E) and periodic acid-Schiff (PAS). RESULTS: Administration of TWEAK increased the mRNA levels of AID, Blimp-1, and IRF4. Treatment with Fn14-Fc suppressed levels of IgG, IgG1, IgG2a, and anti-dsDNA Ab in sera and reduced numbers of B, plasma, and follicular helper T (Tfh) cells in spleens of sanroque mice. In addition, renal protective effects of Fn14-Fc were shown. CONCLUSION: Fn14-Fc had beneficial effects in a SLE mouse model by repressing B cells, plasma cells, Tfh, and renal damage. This suggested that Fn14-Fc represents a potential therapeutic agent for SLE.

Activation of human natural killer cells by the soluble form of cellular prion protein.

Cellular prion protein (PrP(C)) is widely expressed in various cell types, including cells of the immune system. However, the specific roles of PrP(C) in the immune system have not been clearly elucidated. In the present study, we investigated the effects of a soluble form of recombinant PrP(C) protein on human natural killer (NK) cells. Recombinant soluble PrP(C) protein was generated by fusion of human PrP(C) with the Fc portion of human IgG1 (PrP(C)-Fc). PrP(C)-Fc binds to the surface of human NK cells, particularly to CD56(dim) NK cells. PrP(C)-Fc induced the production of cytokines and chemokines and the degranulation of granzyme B from NK cells. In addition, PrP(C)-Fc facilitated the IL-15-induced proliferation of NK cells. PrP(C)-Fc induced phosphorylation of ERK-1/2 and JNK in NK cells, and inhibitors of the ERK or the JNK pathways abrogated PrP(C)-Fc-induced cytokine production in NK cells. In conclusion, the soluble form of recombinant PrP(C)-Fc protein activates human NK cells via the ERK and JNK signaling pathways.

Secreted human glycyl-tRNA synthetase implicated in defense against ERK-activated tumorigenesis.

Although adaptive systems of immunity against tumor initiation and destruction are well investigated, less understood is the role, if any, of endogenous factors that have conventional functions. Here we show that glycyl-tRNA synthetase (GRS), an essential component of the translation apparatus, circulates in serum and can be secreted from macrophages in response to Fas ligand that is released from tumor cells. Through cadherin (CDH)6 (K-cadherin), GRS bound to different ERK-activated tumor cells, and released phosphatase 2A (PP2A) from CDH6. The activated PP2A then suppressed ERK signaling through dephosphorylation of ERK and induced apoptosis. These activities were inhibited by blocking GRS with a soluble fragment of CDH6. With in vivo administration of GRS, growth of tumors with a high level of CDH6 and ERK activation were strongly suppressed. Our results implicate a conventional cytoplasmic enzyme in translation as an intrinsic component of the defense against ERK-activated tumor formation.

A Retrospective study on the association between vitreous degeneration and cataract in dogs.

OBJECTIVE: This study was performed to evaluate the relationship between cataract and vitreous degeneration on ultrasonography (VDU) in dogs. MATERIALS AND METHODS: Medical records of dogs were retrospectively reviewed. The dogs presented at the Veterinary Medical Teaching Hospital of Seoul National University from January 2009 to December 2011 for ocular ultrasonography to investigate the suitability of the patient for cataract surgery. A total of 97 dogs (179 eyes) were included in this study. Data collected included age, gender, ophthalmic examination, and ultrasonographic examination. Cataract was classified into five grades by ophthalmic examination (0: normal, 1: incipient, 2: immature, 3: mature, and 4: hypermature). VDU was classified into 4 grades (0: no degeneration, 1: mild vitreous degeneration, 2: moderate vitreous degeneration, and 3: marked vitreous degeneration). RESULTS: The mean rank of VDU grades increased with the progression of cataracts, and statistical significant differences were shown between cataracts grade 0 and 2 (P = 0.010), between 0 and 3 (P < 0.001), between 0 and 4 (P = 0.010), between 1 and 3 (P = 0.03), between 1 and 4 (P = 0.02), and between 2 and 4 (P = 0.04). There were no significant differences in age and gender according to the cataract grades. There was no statistical significant difference in the mean rank of VDU grades between cataractous eyes with lens-induced uveitis (LIU) and those without LIU. CONCLUSIONS: The results indicated that increased VDU was associated with more severe cataract grades in dogs.

Corneal plaque containing levofloxacin in a dog.

A 13-year-old castrated male Yorkshire terrier developed a corneal ulcer 2 weeks after intracapsular lens extraction (ICLE) in the right eye. The corneal ulcer was treated with levofloxacin eye drops. A plaque with a white luster developed in the central cornea 2 weeks after treatment with levofloxacin eye drops. The corneal plaque was surgically removed under inhalant anesthesia. The corneal plaque displayed antimicrobial activity against Escherichia coli. Furthermore, levofloxacin content in the plaque was confirmed by matrix-assisted laser desorption/ionization time-of-flight/time-of-flight (MALDI-TOF/TOF) mass spectrometry (MS). The corneal ulcer completely resolved 2 weeks after the surgical removal of the corneal lesion and replacement of levofloxacin eye drops with tobramycin eye drops. Although the topical use of levofloxacin is unlikely to lead to corneal chemical deposits due to the high water solubility of the drug compared to other topical fluoroquinolones, this patient developed corneal plaque of the antibiotic drop.

Structural analysis and insight into metal-ion activation of the iron-dependent regulator from Thermoplasma acidophilum.

The iron-dependent regulator (IdeR) is a metal ion-activated transcriptional repressor that regulates the expression of genes encoding proteins involved in iron uptake to maintain metal-ion homeostasis. IdeR is a functional homologue of the diphtheria toxin repressor (DtxR), and both belong to the DtxR/MntR family of metalloregulators. The structure of Fe(2+)-bound IdeR (TA0872) from Themoplasma acidophilum was determined at 2.1 Å resolution by X-ray crystallography using single-wavelength anomalous diffraction. The presence of Fe(2+), which is the true biological activator of IdeR, in the metal-binding site was ascertained by the use of anomalous difference electron-density maps using diffraction data collected at the Fe absorption edge. Each DtxR/IdeR subunit contains two metal ion-binding sites separated by 9 Å, labelled the primary and ancillary sites, whereas the crystal structures of IdeR from T. acidophilum show a binuclear iron cluster separated by 3.2 Å, which is novel to T. acidophilum IdeR. The metal-binding site analogous to the primary site in DtxR was unoccupied, and the ancillary site was occupied by binuclear clustered ions. This difference suggests that T. acidophilum IdeR and its closely related homologues are regulated by a mechanism distinct from that of either DtxR or MntR. T. acidophilum IdeR was also shown to have a metal-dependent DNA-binding property by electrophoretic mobility shift assay.