The utility of Vibratip in accurate identification of loss of protective sensation in the contralateral foot of patients admitted with a diabetic foot ulcer.

BACKGROUND AND AIMS: Diabetic foot ulcer (DFU) is a debilitating complication of type 2 DM. Complexity of foot examination often precludes proper clinical assessment of the foot during routine evaluation. We assessed the utility of novel device, vibratip, both singly and in combination with standard bedside tools for assessment of loss of protective sensation. METHODS: 75 patients admitted with DFU were included in the study. Clinical examination of the contralateral foot was done - temperature perception, vibration, pinprick sensation, Achilles tendon reflex and Neuropathy disability score were assessed. Testing using 10 g Monofilament, Vibratip and biothesiometer were also done. Considering the biothesiometer as the reference standard, three bedside tests (Vibratip, 10 g monofilament and 128 Hz tuning fork) were compared against it singly and in combinations. RESULTS: When compared against biothesiometer, vibratip performed significantly well with a positive predictive value of 90.3% and specificity of 84.2%. Sensitivity, however, was only 50%. On combining bedside tests, the best combination strategy was seen with vibratip and 10 g monofilament, which improved the sensitivity to 62.5%. Combining all three bedside tests further improved sensitivity to 64.3%. CONCLUSION: All the patients with an at-risk foot may not be identified with vibratip alone. Nevertheless, an abnormal result is almost always associated with loss of protective sensation, and such persons should be suitably educated. LIMITATIONS: Due to small size of the study population, it is not possible to generalize the findings to all patients with diabetes mellitus. A larger study would be required to provide more confirmatory findings.

Crystallizing galactocele: Report of a rare variation.

The physiological changes of the breast during pregnancy and lactation make the clinical, radiological and pathological evaluation of a breast mass challenging. Galactoceles are benign lesions containing milk, and generally occur post partum. Fine needle aspiration cytology is a simple, quick and effective technique for the diagnosis of the same during this period, and in case of galactocele the same can be both diagnostic and therapeutic.Although the cytological features of galactocele are straight forward, a few rare interesting variations can be encountered posing a diagnostic challenge to the reporting cytopathologist. We present a case of galactocele in a twenty five year old lactating female with tyrosine crystals on cytology. Milk is composed of a wide variety of proteins and minerals, leading to the formation of calcium lactate or tyrosine crystals under rare circumstances when the milieu is acidic. This is one of the rare cases of crystallizing galactoceles reported in literature till date.

Nonhemophilic hemosiderotic synovitis of the knee: a case report and review of literature.

Synovium is specialized mesenchymal tissue lining the inner surface of the joint capsule and is the site for a series of pathologic processes that are characteristic, and in some cases specific, to this distinctive tissue. Hemosiderotic synovitis is a rare and inadequately defined synovial proliferative disorder, which develops with recurrent hemorrhages in the joint. The most affected joint from bleeding is the knee whatever the etiology is. Repeated hemarthrosis may produce significant structural alteration of joints leading to chronic osteoarthritis. The most common cause is hereditary clotting factor deficiency diseases like hemophilia. We report a rare case of nonhemophilic hemosiderotic synovitis of the knee joint, in which the patient lacks history of any bleeding diathesis. Its definitive diagnosis was possible only by histopathological examination. The prompt recognition of this distinct subtype of hemosiderotic synovitis and awareness of underlying causes should lead to earlier diagnosis, appropriate therapy, less joint destruction, and better outcomes.

Susceptibility profile of Gram-negative bacteremic isolates to beta lactam-beta lactamase inhibitor agents in comparison to other antibiotics.

BACKGROUND: Comprehensive understanding about the local antibiogram is an essential requirement for preparation of hospital or unit based antibiotic policy. Bacteremic isolates are the most useful ones for this purpose, representing invasive disease. OBJECTIVE: To analyze susceptibility pattern of bacteremic Gram-negative isolates in our center, to various antibiotics, including beta lactam-beta lactamase inhibitor (BL-BLI) agents and carbapenem. MATERIALS AND METHODS: This is a retrospective study done in Apollo Specialty Hospital, a tertiary care oncology center in South India. The susceptibility of Escherichia coli, Klebsiella, Acinetobacter and Pseudomonas blood culture isolates, identified between January 2013 and June 2014 to various antibiotics were analyzed. RESULTS: A total of 231-Gram-negative bacteremic isolates were analyzed. ESBL rate among E. coli isolates was 82.7% (67 out of 81) and 74.3% (58 out of 78) in Klebsiella. Carbapenem (imipenem) susceptibility rate in E. coli was 76.5%, Klebsiella 58.9%, Acinetobacter 32% and Pseudomonas 77.2%. Colistin susceptibility in E. coli was 96.2%, Klebsiella 93.5%, Acinetobacter 92.8% and Pseudomonas 97.7%. Difference in the susceptibility of Enterobacteriaceae to BL-BLI agents (especially cefepime-tazobactam) and carbapenem were minimal. In nonfermenters, BL-BLI susceptibility was better than that of carbapenem. CONCLUSION: Findings of the study make a strong argument for using BL-BLI agents and sparing carbapenem to curtail the spiraling scenario of carbapenem resistance.

Soft glass rheology in liquid crystalline gels formed by a monodisperse dipeptide.

Thermal and extensive rheological characterization of a nematic liquid crystal gelated with a novel monodisperse dipeptide, also a liquid crystal, has been carried out. For certain concentrations, the calorimetric scans display a two-peak profile across the chiral nematic-isotropic (N*-I) transition, a feature reminiscent of the random-dilution to random-field crossover observed in liquid crystal gels formed with aerosil particles. All samples show shear thinning behavior without a Newtonian plateau region at lower shear rates. Small deformation oscillatory data at lower frequencies exhibit a frequency dependence of the storage (G') and loss (G'') moduli that can be described by a weak power-law, characteristic of soft glassy rheological systems. At higher frequencies, while lower concentration composites have a strong frequency dependence with a trend for possible crossover from viscoelastic solid to viscoelastic liquid behavior, the higher-concentration gels show frequency-independent rheograms of entirely elastic nature G' > G''. The plateau modulus of G' is described by a power-law with an exponent again common to soft materials, such as foams, slurries, etc. Other features which are a hallmark of such materials observed in the present study are: (i) above a critical strain, a strain softening of the moduli with a peak in the loss modulus, (ii) power-law variation of the storage modulus in the nonlinear viscoelastic regime, and (iii) absence of Cox-Merz superposition for the complex viscosity. An attractive feature of these gels is the fast recovery upon removal of large strain and qualitatively different temporal behavior of the recovery between the low and high concentration composites, with the latter indicating the presence of two characteristic time scales.

Fast responding robust nematic liquid crystalline gels formed by a monodisperse dipeptide: electro-optic and rheological studies.

Realization of mechanically robust electrically fast responding liquid crystal devices with low operating voltage is one of the current research interests. Here we report a gel system comprising a commercially available nematic liquid crystal material and a new monodisperse dipeptide liquid crystalline organogelator that results in these properties. The gels exhibit nearly 2 orders of magnitude faster switching response than the pure nematic liquid crystal while having 3 orders of magnitude higher zero shear rate viscosity, and with the attractive feature that the switching threshold voltage is hardly altered. Electro-optic and rheological studies of this system are described here.

Quantitative Analysis of STD-NMR Spectra of Reversibly Forming Ligand-Receptor Complexes.

We describe our work on the quantitative analysis of STD-NMR spectra of reversibly forming ligand-receptorcomplexes. This analysis is based on the theory of complete relaxation and conformational exchange matrixanalysis of saturation transfer (CORCEMA-ST) effects. As part of this work, we have developed two separateversions of the CORCEMA-ST program. The first version predicts the expected STD intensities for a givenmodel of a ligand-protein complex, and compares them quantitatively with the experimental data.This version is very useful for rapidly determining if a model for a given ligand-proteincomplex is compatible with the STD-NMR data obtained in solution. It is also useful in determining theoptimal experimental conditions for undertaking the STD-NMR measurements on a given complex by computersimulations. In the second version of the CORCEMA-ST program, we have implemented a torsion anglerefinement feature for the bound ligand within the protein binding pocket. In this approach, the globalminimum for the bound ligand conformation is obtained by a hybrid structure refinement protocol involvingCORCEMA-ST calculation of intensities and simulated annealing refinement of torsion angles of the boundligand using STD-NMR intensities as experimental constraints to minimize a pseudo-energy function.This procedure is useful in refining and improving the initial models based on crystallography, computerdocking, or other procedures to generate models for the bound ligand within the protein binding pocket compatiblewith solution STD-NMR data. In this chapter we describe the properties of the STD-NMR spectra, includingthe dependence of the intensities on various parameters. We also describe the results of the CORCEMA-STanalyses of experimental STD-NMR data on some ligand-protein complexes to illustrate the quantitativeanalysis of the data using this method. This CORCEMA-ST program is likely to be useful in structure-baseddrug design efforts.

Evidence of wormlike micellar behavior in chromonic liquid crystals: rheological, X-ray, and dielectric studies.

We report rheological, X-ray, and dielectric investigations on a chromonic liquid-crystalline system formed by aqueous solutions of a food coloring agent, Sunset Yellow, in the absence and upon addition of salt. The salt-concentration dependence of the steady-state viscosity at low shear rates has a non-monotonic variation and is qualitatively similar to the behavior seen in wormlike micellar systems, a surprising result since chromonic systems are expected to be non-micellar in character. More interestingly, for a particular low concentration of the salt (20 mM), the viscosity increases by 3 orders of magnitude in comparison with that of the pure chromonic material. The dynamic (oscillatory) rheological data bring out features which can be described in terms of a microstructure formation. X-ray and dielectric studies show that certain characters of the aggregates formed by the Sunset Yellow molecules are not altered by the addition of salt.

Kinetics of the thermal back relaxation time of the photoinduced nematic-isotropic transition.

We report on the temperature dependence of the response time for the photochemical and thermal back relaxation processes observed in a material exhibiting a photostimulated, isothermal nematic-isotropic phase transition. It is found that the time required for the system to achieve the photostationary state as well as to recover the original state after photoirradiation with a uv beam is a smooth function of the absolute temperature of the sample, except in the vicinity of the transition. The duration of the recovery can be split into two parts: delay time and response time. Using a simple description based on the Maier-Saupe model, we show that the temperature dependence of the response time can be understood in terms of the order parameter excess between the equilibrium and photostimulated states.

Reconstruction for proton computed tomography by tracing proton trajectories: a Monte Carlo study.

Proton computed tomography (pCT) has been explored in the past decades because of its unique imaging characteristics, low radiation dose, and its possible use for treatment planning and on-line target localization in proton therapy. However, reconstruction of pCT images is challenging because the proton path within the object to be imaged is statistically affected by multiple Coulomb scattering. In this paper, we employ GEANT4-based Monte Carlo simulations of the two-dimensional pCT reconstruction of an elliptical phantom to investigate the possible use of the algebraic reconstruction technique (ART) with three different path-estimation methods for pCT reconstruction. The first method assumes a straight-line path (SLP) connecting the proton entry and exit positions, the second method adapts the most-likely path (MLP) theoretically determined for a uniform medium, and the third method employs a cubic spline path (CSP). The ART reconstructions showed progressive improvement of spatial resolution when going from the SLP [2 line pairs (lp) cm(-1)] to the curved CSP and MLP path estimates (5 lp cm(-1)). The MLP-based ART algorithm had the fastest convergence and smallest residual error of all three estimates. This work demonstrates the advantage of tracking curved proton paths in conjunction with the ART algorithm and curved path estimates.

Determination of the conformation of trimethoprim in the binding pocket of bovine dihydrofolate reductase from a STD-NMR intensity-restrained CORCEMA-ST optimization.

Dihydrofolate reductase (DHFR) is a pharmacologically important intracellular target enzyme for folate antagonists, including the antibacterial agent trimethoprim (TMP). The structures of DHFR from various sources with and without the bound ligands have been determined by X-ray crystallography and solution NMR spectroscopy. However, there is no crystal or solution NMR structure for the bovine DHFR/TMP complex. Here we report the solution structure of TMP within the binding pocket of bovine DHFR using a novel method developed in our laboratory, viz., STD-NMR intensity-restrained CORCEMA-ST optimization (SICO) utilizing experimental STD data on this complex, and demonstrate that its solution structure is essentially identical to the one in the crystal structure of the homologous chicken liver DHFR/TMP complex. The excellent agreement we obtain between the experimental and predicted STDs also serves as a validation of the CORCEMA-ST methodology.

Refinement of the conformation of UDP-galactose bound to galactosyltransferase using the STD NMR intensity-restrained CORCEMA optimization.

The STD NMR technique has originally been described as a tool for screening large compound libraries to identify the lead compounds that are specific to target proteins of interest. The application of this technique in the qualitative epitope mapping of ligands weakly binding to proteins, virus capsid shells, and nucleic acids has also been described. Here we describe the application of the STD NMR intensity-restrained CORCEMA optimization (SICO) procedure for refining the bound conformation of UDP-galactose in galactosyltransferase complex using STD NMR intensities recorded at 500 MHz as the experimental constraints. A comparison of the SICO structure for the bound UDP-galactose in solution with that in the crystal structure for this complex shows some differences in ligand torsion angles and V253 side-chain orientation in the protein. This work describes the first application of an STD NMR intensity-restrained CORCEMA optimization procedure for refining the torsion angles of a bound ligand structure. This method is likely to be useful in structure-based drug design programs since most initial lead compounds generally exhibit weak affinity (millimolar to micromolar) to target proteins of pharmaceutical interest, and the bound conformation of these lead compounds in the protein binding pocket can be determined by the CORCEMA-ST refinement.

CORCEMA refinement of the bound ligand conformation within the protein binding pocket in reversibly forming weak complexes using STD-NMR intensities.

We describe an intensity-restrained optimization procedure for refining approximate structures of ligands within the protein binding pockets using STD-NMR intensity data on reversibly forming weak complexes. In this approach, the global minimum for the bound-ligand conformation is obtained by a hybrid structure refinement method involving CORCEMA calculation of intensities and simulated annealing optimization of torsion angles of the bound ligand using STD-NMR intensities as experimental constraints and the NOE R-factor as the pseudo-energy function to be minimized. This method is illustrated using simulated STD data sets for typical carbohydrate and peptide ligands. Our procedure also allows for the optimization of side chain torsion angles of protein residues within the binding pocket. This procedure is useful in refining and improving initial models based on crystallography or computer docking or other algorithms to generate models for the bound ligand (e.g., a lead compound) within the protein binding pocket compatible with solution STD-NMR data. This method may facilitate structure-based drug design efforts.

Saturation transfer difference NMR and computational modeling of a sialoadhesin-sialyl lactose complex.

The siglecs are a family of I-type lectins binding to sialic acids on the cell surface. Sialoadhesin (siglec-1) is expressed at much higher levels in inflammatory macrophages and specifically binds to alpha-2,3-sialylated N-acetyl lactosamine residues of glycan chains. The terminal disaccharide alpha-D-Neu5Ac-(2-->3)-beta-D-Gal is thought to be the main epitope recognized by sialoadhesin. To understand the basis of this biological recognition reaction we combined NMR experiments with a molecular modeling study. We employed saturation transfer difference (STD) NMR experiments to characterize the binding epitope of alpha-2,3-sialylated lactose, alpha-D-Neu5Ac-(2-->3)-beta-D-Gal-(1-->4)-D-Glc 1 to sialoadhesin at atomic resolution. The experimental results were compared to a computational docking model and to X-ray data of a complex of sialyl lactose and sialoadhesin. The data reveal that sialoadhesin mainly recognizes the N-acetyl neuraminic acid and a small part of the galactose moiety of 1. The crystal structure of a complex of sialoadhesin with sialyl lactose 1 was used as a basis for a modeling study using the FlexiDock algorithm. The model generated was very similar to the original crystal structure. Therefore, the X-ray data were used to predict theoretical STD values utilizing the CORCEMA-STD protocol. The good agreement between experimental and theoretical STD values indicates that a combined modeling/STD NMR approach yields a reliable structural model for the complex of sialoadhesin with alpha-D-Neu5Ac-(2-->3)-beta-D-Gal-(1-->4)-D-Glc 1 in aqueous solution.

Complete relaxation and conformational exchange matrix (CORCEMA) analysis of intermolecular saturation transfer effects in reversibly forming ligand-receptor complexes.

A couple of recent applications of intermolecular NOE (INOE) experiments as applied to biomolecular systems involve the (i) saturation transfer difference NMR (STD-NMR) method and (ii) the intermolecular cross-saturation NMR (ICS-NMR) experiment. STD-NMR is a promising tool for rapid screening of a large library of compounds to identify bioactive ligands binding to a target protein. Additionally, it is also useful in mapping the binding epitopes presented by a bioactive ligand to its target protein. In this latter application, the STD-NMR technique is essentially similar to the ICS-NMR experiment, which is used to map protein-protein or protein-nucleic acid contact surfaces in complexes. In this work, we present a complete relaxation and conformational exchange matrix (CORCEMA) theory (H. N. B. Moseley et al., J. Magn. Reson. B 108, 243-261 (1995)) applicable for these two closely related experiments. As in our previous work, we show that when exchange is fast on the relaxation rate scale, a simplified CORCEMA theory can be formulated using a generalized average relaxation rate matrix. Its range of validity is established by comparing its predictions with those of the exact CORCEMA theory which is valid for all exchange rates. Using some ideal model systems we have analyzed the factors that influence the ligand proton intensity changes when the resonances from some protons on the receptor protein are saturated. The results show that the intensity changes in the ligand signals in an intermolecular NOE experiment are very much dependent upon: (1) the saturation time, (2) the location of the saturated receptor protons with respect to the ligand protons, (3) the conformation of the ligand-receptor interface, (4) the rotational correlation times for the molecular species, (5) the kinetics of the reversibly forming complex, and (6) the ligand/receptor ratio. As an example of a typical application of the STD-NMR experiment we have also simulated the STD effects for a hypothetical trisaccharide bound to a protein. The CORCEMA theory for INOE and the associated algorithm are useful in a quantitative interpretation of the intensity changes in the ligand in both the STD-NMR and ICS-NMR, provided the identity of the receptor protons experiencing direct RF saturation is known. The formalism presented here is likely to be useful in the design of bioactive ligands to a specific target protein and in the quantitative mapping of binding epitopes and interfaces between molecules in complexes.