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Abstract Background Osteosarcoma (OSA) is a common malignant bone tumor of large breed dogs that occurs at predictable anatomic sites. At the time of initial diagnosis, most affected dogs have occult pulmonary metastases. Even with aggressive surgical treatment combined with chemotherapy, the majority of dogs diagnosed with OSA live less than 1 year from the time of diagnosis. The ability to identify canine OSA cases most responsive to treatment is needed. In humans, OSA is also an aggressive tumor that is histologically and molecularly similar to canine OSA. The expression of the tumor suppressor gene product P16 by human OSA tissue has been linked to a favorable response to chemotherapy. Results We identified an antibody that binds canine P16 and developed a canine OSA tissue microarray in order to test the hypothesis that P16 expression by canine OSA tissue is predictive of clinical outcome following amputation and chemotherapy. Although statistical significance was not reached, a trend was identified between the lack of canine OSA P16 expression and a shorter disease free interval. Conclusions The identification of a molecular marker for canine OSA is an important goal and the results reported here justify a larger study.

This article presents a comprehensive study on the impact of irradiation optical fiber cores with a femtosecond-pulsed laser, operating at a wavelength of 1030 nm, on the signal amplitude in Rayleigh scattering-based optical frequency domain reflectometry (OFDR). The experimental study involves two fibers with significantly different levels of germanium doping: the standard single-mode fiber (SMF-28) and the ultra-high numerical aperture fiber (UHNA7). The research findings reveal distinct characteristics of reflected and scattered light amplitudes as a function of pulse energy. Although different amplitude changes are observed for the examined fibers, both can yield an enhancement of amplitude. The paper further investigates the effect of fiber Bragg grating inscription on the overall amplitude of reflected light. The insights gained from this study could be beneficial for controlling the enhancement of light scattering amplitude in fibers with low or high levels of germanium doping.

Fibre optic sensors using tilted fibre Bragg grating (TFBG) have high sensitivity for refractive index measurements. In order to achieve good metrological parameters of the measurement, an appropriate method of spectrum demodulation must be used. The method proposed in the article is an improvement of the spectral length algorithm. The spectral length parameter is treated as the sum of the derivative filter responses. In the original version, the first difference of spectrum elements was used, while this article proposes to use the wavelet transform to calculate the numerical derivative approximation. The advantage of this solution is an easy way to select the level of smoothing filtration by changing the scale parameter. The derivation is appropriate even for a relatively low signal-to-noise level. The approximation of the spectral length by the derivative calculated using the wavelet transform eliminates the high-frequency noise of the optical signal. The absolute value of determined spectral derivatives after significant smoothing can be used to estimate the wavelength of the decay of modes. After analyzing experimental data and performing calculations, it turns out that this is a linear method with better resolution than the contour length algorithm.

The development of fibre optic sensors for measuring the refractive index is related to the creation of new periodic structures and demodulation algorithms for the measured spectrum. Recently, we proposed a double-comb Tilted fibre Bragg grating (DCTFBG) structure. In this article, we analyse such a structure for measuring the refractive index in comparison to a single classical structure. Increasing the number of modes causes a significant change in the Fourier spectrum of optical spectra. For the purpose of data pre-processing, we propose the Fourier Transform as a filtering method in the frequency domain. Then, we analyse separately the band-filtered optical spectra for several frequency ranges. For quantitative analysis, we use algorithms that use quantitative changes in the transmission, i.e., the method of the envelope and the length of the spectrum contour. We propose the use of the Hilbert transform as the envelope method. The second type of algorithms used are methods determining the shift of spectrum features along the wavelength axis. The method of determining the centre of gravity of the area bounded by the envelope and the maximum of the second derivative of the smoothed cumulative spectrum contour length is proposed here. Using the developed methods, the measurement resolution was achieved at the level of 2 × 10 -5 refractive index unit.

The purpose of this work is the authors' attempt to identify the main phases of information transformation in measurement channels on the example of an optical measurement channel with microprocessor control. The authors include such phases: hardware implementation and analytical representation of an optical sensor's converting functions and a current-to-voltage converter; based on the methods of experimental computer science, the converting functions and sensitivity are deduced, analytical dependences for estimation of a range of measurement are obtained. It is shown that the choice of information transmission type in the microprocessor measuring channel significantly affects the speed of the measuring channel. Based on the uncertainty in the form of entropy before and after measurements, the amount of information for measuring channels with optoelectronic sensors is estimated. The application of the results obtained in the work allows even at the design stage of physical and mathematical modeling to assess the basic static metrological characteristics of measuring channels, aimed at reducing the stage of development and debugging of hardware and software and standardization of their metrological characteristics.

Tilted fibre Bragg grating (TFBG) are used as sensors to determine many quantities such as refractive index, temperature, stress, rotation and bending. The TFBG spectrum contains a lot of information and various algorithms are used for its analysis. However, most of these algorithms are dedicated to the analysis of spectral changes under the influence of the refractive index. The most popular algorithm used for this purpose is to calculate the area occupied by cladding modes. Among the remaining algorithms, there are those that use the determination of the cut-off wavelength as a surrounding refractive index (SRI) indicator. Projection on the wavelength axis can also be used to calculate the bending radius of the fibre. However, this is a more difficult task than with SRI, because the mode decay in bending is not so easy to catch. In this article, we propose a multi-step algorithm that allows to determine the impact of bending on mode leakage. At the same time, the place on the wavelength from the side of the Bragg mode and the ghost mode is determined, which represents the cladding mode radiated from the cladding under the influence of bending. The developed algorithm consists of the following operations carried out on the transmission spectrum: Fourier filtering, calculation of the cumulative value of the spectral length, low-pass filtering of the cumulative curve or its corresponding polynomial approximation, determination of the first and second derivative of the approximated curve, and projection of the second derivative of the curve on the wavelength axis. The shift of the wavelength determined in this way indirectly indicates the bending radius of the optical fibre. Based on multiple measurements, we prove that the presented algorithm provides better results when determining the bending radius compared to other algorithms adopted for this purpose and proposed for SRI measurements. Additionally, we analyse the method of determining the shift of a fragment of the spectrum using the phase of the discrete Fourier transform.

Background: Doxorubicin (DOX) is one of the most effective chemotherapeutics for canine high-grade lymphoma. In addition to dose-dependent chronic cardiotoxicity, DOX can trigger acute cardiac arrhythmias during drug infusion. Diphenhydramine premedication is commonly used, as histamine release is a proposed mechanism for DOX-associated arrhythmogenesis. Hypothesis/Objectives: The study objectives were to evaluate the incidence and severity of DOX infusion-related cardiac arrhythmias in dogs with high-grade lymphoma and evaluate the effect of diphenhydramine premedication on arrhythmia frequency and severity during and after DOX infusion. Animals: Twenty-two client-owned dogs with cytologically/histopathologically confirmed high-grade lymphoma were recruited, of which 19 were enrolled and 9 completed the study. Methods: Dogs were screened by echocardiogram and concurrent electrocardiogram for this randomized prospective crossover study. Group A received no premedication for DOX #1 and was premedicated with diphenhydramine for DOX #2; Group B received diphenhydramine with DOX #1 and no premedication for DOX #2. For both visits, Holter monitor data were collected for 1 h pre-DOX and 3 h post-DOX administration. Results: Nineteen dogs were enrolled and 9 dogs [Group A (5), Group B (4)] completed the protocol. There was no statistical difference between the DOX alone and DOX + diphenhydramine when evaluating the total number of ventricular premature complexes (VPCs, P = 0.34), change in VPCs/hour ( P = 0.25), total number of atrial premature complexes (APCs, P = 0.5), change in APCs/hour ( P = 0.06), or ventricular arrhythmia severity score ( P > 0.99). Conclusions and clinical importance: This study demonstrates that in these dogs with rigorous pretreatment cardiovascular screening, DOX infusion did not induce significant arrhythmias. Furthermore, these data suggest that, with this screening approach, diphenhydramine may not alter the arrhythmia number or severity in canine DOX recipients., (Copyright © 2020 Willcox, Belanger, Burton, Yu, Ueda, Visser, Skorupski and Stern.)

This article presents the use of a sensor with fiber Bragg grating along with an interrogation system used for monitoring the overhead lines' wire elongation. The possible interrogation methods based on adjusted filters were considered. In the experimental part, three types of fiber Bragg grating pairs, characterized by a small shift in spectra in pairs and gratings with exact matching, were examined. The study showed that, by choosing the appropriate mechanical parameters of the elongation transformer with the optical parameters of the sensor and dedicated filter, the optomechanical system can be adjusted to the required range of overhead line wire sag observation. The range of sag depends on the distance between the poles, the wire type, and its real length in the span, which effectively determines the sag.

The AraC/XylS-family transcriptional regulator ToxT is the master virulence activator of Vibrio cholerae , the gram-negative bacterial pathogen that causes the diarrheal disease cholera. Unsaturated fatty acids (UFAs) found in bile inhibit the activity of ToxT. Crystal structures of inhibited ToxT bound to UFA or synthetic inhibitors have been reported, but no structure of ToxT in an active conformation had been determined. Here we present the 2.5 Å structure of ToxT without an inhibitor. The structure suggests release of UFA or inhibitor leads to an increase in flexibility, allowing ToxT to adopt an active conformation that is able to dimerize and bind DNA. Small-angle X-ray scattering was used to validate a structural model of an open ToxT dimer bound to the cholera toxin promoter. The results presented here provide a detailed structural mechanism for virulence gene regulation in V. cholerae by the UFA components of bile and other synthetic ToxT inhibitors., Competing Interests: Competing interestsThe authors declare no competing interests., (© The Author(s) 2019.)

In this Letter, it has been shown that the twisting of TFBGs (tilted fiber Bragg gratings) decreases their sensitivity to the polarization of the input light. It has been proved by a theoretical simulation study that twisting the TFBG by 180° eliminates the sensitivity of the grating to input light polarization changes. We have experimentally proved that our structure produced has an 18 times lower coefficient of variation of transmission for polarization changes than the untwisted TFBG. This Letter also presents a new method for manufacturing the twisted tilted fiber Bragg grating (TTFBG). We have demonstrated the possibility of writing the TTFBG structure twisted by 90° on a fiber with a length of 10 mm. The structure has been further twisted in the other direction by 90°, which is consistent with a structure twisted by 180°. The properties of both structures were determined. Due to the fiber's strength, the TTFBG twisted by 180° has to be 2 cm long. An advantage of the proposed method of producing the TTFBG is that there is a twist of the structure itself after fabrication. This creates new possibilities of using the structure in many applications. This type of grating can be used to reduce the sensitivity to polarization in various sensing applications, in particular, to measure the refractive index. In addition, a 180° twisted TTFBG has properties of direction discrimination in twist sensing applications.

Squamous cell carcinoma is the most common oral cancer in the cat and presents as a locally aggressive lesion for which an effective therapeutic protocol remains elusive. Feline oral squamous cell carcinoma (OSCC) shares many clinical characteristics with human head and neck squamous cell carcinoma (HNSCC). Accordingly, present studies were conducted to determine similarities for immune markers shared by feline OSCC and human HNSCC. Biopsies harvested from a feline patient cohort-1 (n = 12) were analyzed for lymphoid cell infiltrates by immunohistochemistry (IHC). Results revealed unique patterns of T cell infiltration involving both neoplastic epithelium and stroma that were detected in most patient tumor biopsies (92%) examined by IHC staining for CD3. Intratumoral B cell infiltrates were detected within tumor stroma only, based on IHC staining for CD79a and CD20 for all patients within the same cohort-1. Infiltration of tumors by a regulatory CD4 T cell subset (Tregs) defined by expression of the forkhead transcription factor FoxP3, was also detected in biopsies from 57% of patients and involved infiltration of neoplastic epithelium and stroma. Patient biopsies were also examined for expression of immunomodulator cyclooxygenase (COX)-2 and revealed positive but weak staining of neoplastic epithelium in a significant proportion of cases (75%). Interestingly, COX-2 expression was detected in both neoplastic epithelium and stroma. Blood collected from a second cohort of feline OSCC patients (n = 9) revealed an increased frequency of circulating CD4+FoxP3+ T cells when compared to healthy adult controls (n = 7) (P = 0.045), although frequencies of CD4+CD25+FoxP3+ T cells were comparable between patients and healthy pet cat controls. Lastly, biopsies from feline OSCC patients were characterized for histologic subtype using a classification scheme previously described for human HNSCC. This analysis revealed the conventional subtype as the predominant variant (75%) with conventional subtypes split evenly between well differentiated and moderately differentiated carcinomas. Two cases were classified as papillary and one case as basaloid subtypes. Correlations between subtype, immune marker scores or circulating Treg frequencies and clinical characteristics or outcome were not detected, most likely due to small patient numbers within patient cohorts. However, findings from these studies provide a preliminary step in the characterization of immune and histologic markers that will be critical to defining prognostic immune markers for feline OSCC and potential targets for testing of immunotherapeutics also relevant to human HNSCC in future studies., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Prognosis of feline gastrointestinal mast cell tumours (FGIMCT), based on limited available literature, is described as guarded to poor, which may influence treatment recommendations and patient outcome. The purpose of this study is to describe the clinical findings, treatment response, and outcome of FGIMCT. Medical records of 31 cats diagnosed with and treated for FGIMCT were retrospectively reviewed. Data collected included signalment, method of diagnosis, tumour location (including metastatic sites), treatment type, cause of death and survival time. Mean age was 12.9 y. Diagnosis was made via cytology (n = 15), histopathology (n = 13) or both (n = 3). Metastatic sites included abdominal lymph node (n = 10), abdominal viscera (n = 4) and both (n = 2). Therapeutic approaches included chemotherapy alone (n = 15), surgery and chemotherapy (n = 7), glucocorticoid only (n = 6) and surgery and glucocorticoid (n = 3). Lomustine (n = 15) and chlorambucil (n = 12) were the most commonly used chemotherapy drugs. Overall median survival time was 531 d (95% confidence interval 334, 982). Gastrointestinal location, diagnosis of additional cancers, and treatment type did not significantly affect survival time. Cause of death was tumour-related or unknown (n = 12) and unrelated (n = 8) in the 20 cats dead at the time of analysis. The prognosis for cats with FGIMCT may be better than previously reported, with 26% of cats deceased from an unrelated cause. Surgical and medical treatments (including prednisolone alone) were both associated with prolonged survival times. Treatment other than prednisolone may not be necessary in some cats. Continued research into prognostic factors and most effective treatment strategies are needed., (© 2017 John Wiley & Sons Ltd.)

AphB is a LysR-type transcriptional regulator (LTTR) that cooperates with a second transcriptional activator, AphA, at the tcpPH promoter to initiate expression of the virulence cascade in Vibrio cholerae. Because it is not yet known whether AphB responds to a natural ligand in V. cholerae that influences its ability to activate transcription, we used a computational approach to identify small molecules that influence its activity. In silico docking was used to identify potential ligands for AphB, and saturation transfer difference nuclear magnetic resonance was subsequently employed to access the validity of promising targets. We identified a small molecule, BP-15, that specifically binds the C-terminal regulatory domain of AphB and increases its activity. Interestingly, molecular docking predicts that BP-15 does not bind in the putative primary effector-binding pocket located at the interface of RD-I and RD-II as in other LTTRs, but rather at the dimerization interface. The information gained in this study helps us to further understand the mechanism by which transcriptional activation by AphB is regulated by suggesting that AphB has a secondary ligand binding site, as observed in other LTTRs. This study also lays the groundwork for the future design of inhibitory molecules to block the V. cholerae virulence cascade, thereby preventing the devastating symptoms of cholera infection.

ToxR is a transmembrane transcription factor that is essential for virulence gene expression and human colonization by Vibrio cholerae. ToxR requires its operon partner ToxS, a periplasmic integral membrane protein, for full activity. These two proteins are thought to interact through their respective periplasmic domains, ToxRp and ToxSp. In addition, ToxR is thought to be responsive to various environmental cues, such as bile salts and alkaline pH, but how these factors influence ToxR is not yet understood. Using NMR and reciprocal pull down assays, we present the first direct evidence that ToxR and ToxS physically interact. Furthermore, using NMR and DSF, it was shown that the bile salts cholate and chenodeoxycholate interact with purified ToxRp and destabilize it. Surprisingly, bile salt destabilization of ToxRp enhanced the interaction between ToxRp and ToxSp. In contrast, alkaline pH, which is one of the factors that leads to ToxR proteolysis, decreased the interaction between ToxRp and ToxSp. Taken together, these data suggest a model whereby bile salts or other detergents destabilize ToxR, increasing its interaction with ToxS to promote full ToxR activity. Subsequently, as V. cholerae alkalinizes its environment in late stationary phase, the interaction between the two proteins decreases, allowing ToxR proteolysis to proceed., (© 2017 John Wiley & Sons Ltd.)

Background: Osteosarcoma (OSA) is a common malignant bone tumor of large breed dogs that occurs at predictable anatomic sites. At the time of initial diagnosis, most affected dogs have occult pulmonary metastases. Even with aggressive surgical treatment combined with chemotherapy, the majority of dogs diagnosed with OSA live less than 1 year from the time of diagnosis. The ability to identify canine OSA cases most responsive to treatment is needed. In humans, OSA is also an aggressive tumor that is histologically and molecularly similar to canine OSA. The expression of the tumor suppressor gene product P16 by human OSA tissue has been linked to a favorable response to chemotherapy., Results: We identified an antibody that binds canine P16 and developed a canine OSA tissue microarray in order to test the hypothesis that P16 expression by canine OSA tissue is predictive of clinical outcome following amputation and chemotherapy. Although statistical significance was not reached, a trend was identified between the lack of canine OSA P16 expression and a shorter disease free interval., Conclusions: The identification of a molecular marker for canine OSA is an important goal and the results reported here justify a larger study.

FadR is a master regulator of fatty acid (FA) metabolism that coordinates the pathways of FA degradation and biosynthesis in enteric bacteria. We show here that a Δ fadR mutation in the El Tor biotype of Vibrio cholerae prevents the expression of the virulence cascade by influencing both the transcription and the posttranslational regulation of the master virulence regulator ToxT. FadR is a transcriptional regulator that represses the expression of genes involved in FA degradation, activates the expression of genes involved in unsaturated FA (UFA) biosynthesis, and also activates the expression of two operons involved in saturated FA (SFA) biosynthesis. Since FadR does not bind directly to the toxT promoter, we determined whether the regulation of any of its target genes indirectly influenced ToxT. This was accomplished by individually inserting a double point mutation into the FadR-binding site in the promoter of each target gene, thereby preventing their activation or repression. Although preventing FadR-mediated activation of fabA , which encodes the enzyme that carries out the first step in UFA biosynthesis, did not significantly influence either the transcription or the translation of ToxT, it reduced its levels and prevented virulence gene expression. In the mutant strain unable to carry out FadR-mediated activation of fabA , expressing fabA ectopically restored the levels of ToxT and virulence gene expression. Taken together, the results presented here indicate that V. cholerae FadR influences the virulence cascade in the El Tor biotype by modulating the levels of ToxT via two different mechanisms. IMPORTANCE Fatty acids (FAs) play important roles in membrane lipid homeostasis and energy metabolism in all organisms. In Vibrio cholerae , the causative agent of the acute intestinal disease cholera, they also influence virulence by binding into an N-terminal pocket of the master virulence regulator, ToxT, and modulating its activity. FadR is a transcription factor that coordinately controls the pathways of FA degradation and biosynthesis in enteric bacteria. This study identifies a new link between FA metabolism and virulence in the El Tor biotype by showing that FadR influences both the transcription and posttranslational regulation of the master virulence regulator ToxT by two distinct mechanisms., (Copyright © 2017 American Society for Microbiology.)

This retrospective case series evaluates the outcome of 21 dogs with grade II stage 2 mast cell tumour (MCT) treated with adequate local therapy and adjuvant systemic chemotherapy (prednisone, vinblastine and CCNU). The median survival for all dogs was 1359 days (range, 188-2340). Median disease-free interval was 2120 days (149-2325 days). Dogs treated with surgery and chemotherapy had shorter survival (median, 1103 days; 188-2010 days) than those that underwent surgery, radiation therapy and chemotherapy as part of their treatment (median, 2056 days; 300-2340 days). Two patients had local recurrence in the radiation field and four patients had de novo MCT. Distant metastasis was not observed in any dogs. The results of this study suggest that, in the presence of loco-regional lymph node metastasis in grade II MCT, the use of prednisone, vinblastine and CCNU after adequate local-regional therapy can provide a median survival in excess of 40 months., (© 2013 Blackwell Publishing Ltd.)

Background: Interleukin (IL)-12 is a pro-inflammatory cytokine that mediates T-helper type 1 responses and cytotoxic T-cell activation, contributing to its utility as anti-cancer agent. Systemic administration of IL-12 often results in unacceptable toxicity; therefore, strategies to direct delivery of IL-12 to tumors are under investigation. The objective of this study was to assist the preclinical development of NHS-IL12, an immunocytokine consisting of an antibody, which targets necrotic tumor regions, linked to IL-12. Specifically this study sought to evaluate the safety, serum pharmacokinetics, anti-tumor activity, and immune modulation of NHS-IL12 in dogs with naturally occurring cancers., Methodology/principal Findings: A rapid dose-escalation study of NHS-IL12 administered subcutaneously to dogs with melanoma was conducted through the Comparative Oncology Trials Consortium (COTC). Eleven dogs were enrolled in four dose-escalation cohorts; thereafter, an additional seven dogs were treated at the defined tolerable dose of 0.8 mg/m2. The expanded cohort at this fixed dose (ten dogs in total) was accrued for further pharmacokinetics and pharmacodynamics assessment. NHS-IL12 levels, serum cytokine concentrations, and peripheral blood mononuclear cell characterization (post-treatment) and draining lymph node immune profiling, and tumor biopsies (pre- and post-treatment) were collected. Adverse events included thrombocytopenia, liver enzymopathies, fever, and vasculitis. Correlation between interferon (IFN)-γ induction, adverse events, and NHS-IL12 exposure (maximum concentration and area under the concentration-time curve) were dose-dependent. Serum IL-10 levels and intratumoral CD8+ populations increased after treatment. Partial responses, according to Response Evaluation Criteria in Solid Tumors (RECIST) criteria, were observed in two dogs treated with NHS-IL12 0.8 mg/m2 and 1.6 mg/m2., Conclusions/significance: NHS-IL12 was administered safely to dogs with melanoma and both immunologic and clinical activity was observed. This study successfully defined a narrow therapeutic window for systemic delivery of NHS-IL12 via the subcutaneous route. Results will inform the design and implementation of first-in-human clinical trials of NHS-IL12 in cancer patients.

Vibrio cholerae O1 is a natural inhabitant of aquatic environments and causes the diarrheal disease, cholera. Two of its primary virulence regulators, TcpP and ToxR, are localized in the inner membrane. TcpP is encoded on the Vibrio Pathogenicity Island (VPI), a horizontally acquired mobile genetic element, and functions primarily in virulence gene regulation. TcpP has been shown to undergo regulated intramembrane proteolysis (RIP) in response to environmental conditions that are unfavorable for virulence gene expression. ToxR is encoded in the ancestral genome and is present in non-pathogenic strains of V. cholerae, indicating it has roles outside of the human host. In this study, we show that ToxR undergoes RIP in V. cholerae in response to nutrient limitation at alkaline pH, a condition that occurs during the stationary phase of growth. This process involves the site-2 protease RseP (YaeL), and is dependent upon the RpoE-mediated periplasmic stress response, as deletion mutants for the genes encoding these two proteins cannot proteolyze ToxR under nutrient limitation at alkaline pH. We determined that the loss of ToxR, genetically or by proteolysis, is associated with entry of V. cholerae into a dormant state in which the bacterium is normally found in the aquatic environment called viable but nonculturable (VBNC). Strains that can proteolyze ToxR, or do not encode it, lose culturability, experience a change in morphology associated with cells in VBNC, yet remain viable under nutrient limitation at alkaline pH. On the other hand, mutant strains that cannot proteolyze ToxR remain culturable and maintain the morphology of cells in an active state of growth. Overall, our findings provide a link between the proteolysis of a virulence regulator and the entry of a pathogen into an environmentally persistent state.

FadR is a master regulator of fatty acid metabolism and influences virulence in certain members of Vibrionaceae. Among FadR homologues of the GntR family, the Vibrionaceae protein is unusual in that it contains a C-terminal 40-residue insertion. Here we report the structure of Vibrio cholerae FadR (VcFadR) alone, bound to DNA, and in the presence of a ligand, oleoyl-CoA. Whereas Escherichia coli FadR (EcFadR) contains only one acyl-CoA-binding site in each monomer, crystallographic and calorimetric data indicate that VcFadR has two. One of the binding sites resembles that of EcFadR, whereas the other, comprised residues from the insertion, has not previously been observed. Upon ligand binding, VcFadR undergoes a dramatic conformational change that would more fully disrupt DNA binding than EcFadR. These findings suggest that the ability to bind and respond to an additional ligand allows FadR from Vibrionaceae to function as a more efficient regulator.

In this Letter, we present the technology of fiber Bragg grating (FBG) inscription in highly birefringent (HB) few-mode microstructured fibers (MSFs) with two different (nanosecond and femtosecond) lasers in a Talbot interferometer setup. The spectral characteristics of FBGs written in the core region of the investigated fiber, with particular modes represented by dual peaks, are presented and discussed. Furthermore, we calculate the fundamental fiber parameters (mode effective refractive index and phase modal birefringence) from the spectral characteristics and show very good agreement with the performed numerical fiber characterization. We expect the results of our experiments to be very useful in future development of FBG sensors based on novel HB MSFs, with enhanced strain sensitivity of higher-order modes.

The Vibrio cholerae BreR protein is a transcriptional repressor of the breAB efflux system operon, which encodes proteins involved in bile resistance. In a previous study (F. A. Cerda-Maira, C. S. Ringelberg, and R. K. Taylor, J. Bacteriol. 190:7441-7452, 2008), we used gel mobility shift assays to determine that BreR binds at two independent binding sites at the breAB promoter and a single site at its own promoter. Here it is shown, by DNase I footprinting and site-directed mutagenesis, that BreR is able to bind at a distal and a proximal site in the breAB promoter. However, only one of these sites, the proximal 29-bp site, is necessary for BreR-mediated transcriptional repression of breAB expression. In addition, it was determined that BreR represses its own expression by recognizing a 28-bp site at the breR promoter. These sites comprise regions of dyad symmetry within which residues critical for BreR function could be identified. The BreR consensus sequence AANGTANAC-N(6)-GTNTACNTT overlaps the -35 region at both promoters, implying that the repression of gene expression is achieved by interfering with RNA polymerase binding at these promoters.

We present the results of theoretical and experimental characterization of a designed and manufactured dual-mode highly birefringent microstructured fiber. We also demonstrate the measured values of polarimetric temperature and strain sensitivity of both the fundamental and second order modes. As the mode field of the second order mode has a strong interaction with the fiber air holes, we observed a significant (over two orders of magnitude) increase in the polarimetric strain sensitivity of this mode in comparison to the fundamental mode. The enhanced strain sensitivity together with the low temperature sensitivity makes our fiber very attractive for application as extremely sensitive temperature independent strain transducers.

Expression of the two critical virulence factors of Vibrio cholerae, toxin-coregulated pilus and cholera toxin, is initiated at the tcpPH promoter by the regulators AphA and AphB. AphA is a winged helix DNA-binding protein that enhances the ability of AphB, a LysR-type transcriptional regulator, to activate tcpPH expression. We present here the 2.2 Å X-ray crystal structure of full-length AphB. As reported for other LysR-type proteins, AphB is a tetramer with two distinct subunit conformations. Unlike other family members, AphB must undergo a significant conformational change in order to bind to DNA. We have found five independent mutations in the putative ligand-binding pocket region that allow AphB to constitutively activate tcpPH expression at the non-permissive pH of 8.5 and in the presence of oxygen. These findings indicate that AphB is responsive to intracellular pH as well as to anaerobiosis and that residues in the ligand-binding pocket of the protein influence its ability to respond to both of these signals. We have solved the structure of one of the constitutive mutants, and observe conformational changes that would allow DNA binding. Taken together, these results describe a pathway of conformational changes allowing communication between the ligand and DNA binding regions of AphB., (© 2011 Blackwell Publishing Ltd.)

The p53 pathway is critical for tumor suppression, as the majority of human cancer has a faulty p53. Here, we identified RNPC1, a p53 target and a RNA-binding protein, as a critical regulator of p53 translation. We showed that ectopic expression of RNPC1 inhibited, whereas knockdown of RNPC1 increased, p53 translation under normal and stress conditions. We also showed that RNPC1 prevented cap-binding protein eIF4E from binding p53 mRNA via its C-terminal domain for physical interaction with eIF4E, and its N-terminal domain for binding p53 mRNA. Consistent with this, we found that RNPC1 directly binds to p53 5' and 3'untranslated regions (UTRs). Importantly, we showed that RNPC1 inhibits ectopic expression of p53 in a dose-dependent manner via p53 5' or 3' UTR. Moreover, we showed that loss of RNPC1 in mouse embryonic fibroblasts increased the level of p53 protein, leading to enhanced premature senescence in a p53-dependent manner. Finally, to explore the clinical relevance of our finding, we showed that RNPC1 was frequently overexpressed in dog lymphomas, most of which were accompanied by decreased expression of wild-type p53. Together, we identified a novel p53-RNPC1 autoregulatory loop, and our findings suggest that RNPC1 plays a role in tumorigenesis by repressing p53 translation.

Dogs with multicentric T-cell lymphoma are commonly treated with CHOP chemotherapy protocols that include cyclophosphamide, doxorubicin, vincristine and prednisone. The purpose of this study was to evaluate the use of CHOP chemotherapy for dogs with multicentric T-cell lymphoma. Identification of prognostic factors in this specific subset of dogs was of secondary interest. Twenty-three out of 24 dogs responded to CHOP chemotherapy and these dogs remained on the protocol for a median of 146 days. No variable was associated with progression free survival (PFS) including stage, substage, hypercalcemia or radiographic evidence of a cranial mediastinal mass. The median overall survival time (OST) for all dogs was 235 days. Dogs that were thrombocytopenic at presentation experienced a significantly longer OST (323 versus 212 days, P=0.01)., (© 2010 Blackwell Publishing Ltd.)

Expression of the ctx and tcp genes, which encode cholera toxin and the toxin coregulated pilus, the Vibrio cholerae O1 virulence determinants having the largest contribution to cholera disease, is repressed by the nucleoid-associated protein H-NS and activated by the AraC-like transcriptional regulator ToxT. To elucidate the molecular mechanism by which H-NS controls transcription of the ctxAB operon, H-NS repression and binding were characterized by using a promoter truncation series, gel mobility shift assays, and DNase I footprinting. Promoter regions found to be important for H-NS repression correlated with in vitro binding. Four main H-NS binding regions are present at ctx. One region overlaps the high-affinity ToxT binding site and extends upstream, another overlaps the ToxT low-affinity binding site around the -35 element, and the remaining two are located adjacent to one another downstream of the transcriptional start site. Competition for binding to the overlapping H-NS/ToxT binding sites was observed in gel mobility shift assays, where ToxT was found to displace H-NS from the ctx promoter region. In addition, regulatory differences between the ctx and tcpA promoters were examined. H-NS was found to have a higher relative binding affinity for the ctx promoter than for the tcpA promoter in vitro. In contrast to ToxT-dependent activation of the tcpA promoter, ToxT activation of ctx did not require the C-terminal domain of the α-subunit of RNA polymerase. These findings demonstrate that transcriptional regulation of ctx and tcpA by H-NS and ToxT is mechanistically distinct, and this may lead to important differences in the expression of these coregulated genes.