Grid Keratotomy for Treatment of Atypical Presenting Indolent Corneal Ulceration in a Boxer

Corneal ulcers are one of the highest causes of vision impairment in dogs. The Boxer breed is particularly predisposed to recurrent and refractory corneal ulcers (Whitley and Gigler, 1999). In this report we present an interesting case of indolent corneal ulcer in a Boxer with atypical clinical manifestation and features, and its successful treatment by grid keratotomy. Boxer ulcers which are also synonymously termed as refractory epithelial erosions, indolent ulcers, recurrent corneal erosions syndrome, rodent ulcers, are superficial corneal ulcers that heal either slowly or poorly (Gelatt 1970, Whitley and Gigler, 1999). Some characteristic features that help to recognize the condition are overlapping lip of non adherent epithelium present around the ulcers edge and stain positive to fluorescein stain and usually occurs bilaterally (Whitley and Gigler, 1999). In our present case the above commonly occurring features were however not present, but after making critical differential diagnosis and considering the breed predisposition the case was identified as an indolent corneal ulcer, and was successfully treated following grid keratotomy. This is an interesting case report on atypical presentation of a boxer ulcer; similar findings have not been reported previously. Keywords: Keratotonmy, Treatment, Corneal ulcer, BoxerNigerian Veterinary Journal 32(2) 201

Anesthesia for Intraocular Surgery in Rabbits

The purpose of the study was to assess a ketamine/xylazine combination along with retrobulbar block using  4% lignocaine HCl for performing intraocular surgery in rabbits. To do so ten healthy adult New Zealand  White rabbits aged 1.5-2 years of either sex weighing 2-3 kgs were selected for unilateral cataract extraction  by phacoemulsification . Xylazine HCl was used as preanesthetic at a dose rate of 5 mg/kg, i.m., followed  by Ketamine HCl at a dose rate of 35mg/kg, i.m. A retro bulbar block was performed with 4% lignocaine  HCL. The anesthetic depth was judged by ear pinching reflex. The time for onset and duration of anesthesia  was found to be 7±0.5 minutes and 35.5±1.2 minutes respectively. A central eyeball fixation following  retro bulbar block was obtained in all the cases. The mean values recorded before induction of anesthesia  and during anesthesia of rectal temperature (38.090C±0.2 vs. 37.290C±0.2), heart rate in beats per minute  (276±1.2 vs.272±1.1), arterial blood pH (7.35±0.02 vs. 7.32±0.02), bicarbonate (16.2±1.2 vs. 20.3±1.8),  PaCo2 (26.09±2.3 vs. 27.52±2.3) and PaO2 (84.79±1.9 vs. 80.39±1.1) did not vary significantly (P>0.05).  Recovery was smooth and complete in 32.5±2.8 minutes. Conclusion: the anesthetic regimen provides adequate condition for conducting intraocular surgery in rabbits.

Stable DHLA–PEG capped PbS quantum dots: from synthesis to near-infrared biomedical imaging

The short shelf-life of water-soluble quantum dots (QDs) due to colloidal instability represents a major drawback to their exploitation. This work examines the colloidal stability of PbS nanoparticles capped with dihydrolipoic acid–polyethylene glycol (DHLA–PEG) ligands terminated with functional groups such as –NH 2 , –COOH, OMe and –N3 and their application for in vivo imaging. We prove a mechanism of colloidal instability and develop a strategy to produce for the first time stable PEG-capped PbS quantum dots with high quantum yield and optical emission in the first and the second near-infrared (NIR) windows of low absorption of biological tissues. The NIR imaging of in vivo biodistribution is demonstrated at wavelengths 4 1000 nm, with benefits of reduced tissue absorption and light scattering. The stability, biocompatibility and potential for further QD functionalization open up realistic prospects for non-invasive bioimaging applications

Investigation of ion dynamics in mixed network former glasses

The work of this thesis is mainly based on the study of structure and ion dynamics of several new ion conducting glasses and to correlate the macroscopic ion transport properties to the glass network structure and the microscopic lengths. The organization of the thesis is as follows Chapter 1 of this thesis deals with the literature review in the field of glasses. A brief introduction to glasses is presented and their exotic features are discussed. The network structures of different type of glasses are briefly discussed. Several theoretical models and concepts used to explain and understand the ion dynamics are pointed out. Finally the scope of the thesis is presented. In chapter 2 a brief description of the preparation technique of glasses and glassnanocomposites and various experimental methods used to characterize them are presented. In the initial part of the chapter the structural characterization such as density, x-ray diffraction (XRD), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM) and Fourier transform infrared (FTIR) spectroscopy techniques are discussed. In the later part, electrical characterization techniques used to study the ion dynamics are presented. In Chapter 3 the structural and electrical properties of xAgI-(1-x)(0.3Ag2O- 0.7(0.5SeO2-0.5MoO3)) glasses have been investigated. The structural characterizations of these glasses have been carried out using XRD, FTIR spectroscopy etc. and the thermal study has been done using Differential Scanning Calorimeter. The Ag+ ion dynamics in the glasses has been investigated in a broad frequency range from 10Hz – 2MHz and in wide temperature range. The dc conductivity and the microscopic lengths obtained from the linear response theory have been correlated to the glass network structure. Chapter 4 deals with the study of mixed former effect and dynamics of Ag+ ions of xAgI-(1-x)(0.3Ag2O-0.7(ySeO2-(1-y)MoO3)) glasses. The glass formation has been confirmed using XRD. The thermodynamic properties of these glasses have been explored using DSC. The modification of the glass network structure has been analyzed using deconvolution of the FTIR spectra. The ionic conductivity of these glasses has been compared to that of the undoped silver selenomolybdate glasses. The study of relaxation dynamics in these glasses has been performed in the framework of the conductivity and the electric modulus formalism. The characteristic lengths obtained from the conductivity and dielectric spectra have been correlated to the modification of the glass network structure. In chapter 5 the study of mixed former effect and ion dynamics in silver ion conducting mixed network former glasses of composition yAg2O-(1-y)(xSeO2-(1-y))TeO2 are presented in wide composition and temperature ranges. The glass network structures and structural modification depending on composition has been investigated using FTIR spectroscopy. The ion dynamics in these mixed former glasses has been studied using the conductivity formalism as a function of frequency and temperature. The correlation of ion transport properties to the microscopic length scales and the glass network structure has been established. In chapter 6 the Ag+ ion dynamics in xAgI-(1-x)(yAg2O-(1-y)(0.5SeO2-O.5TeO2)) mixed network former glasses for different modifier content is presented. The thermal properties of these glasses have been studied using DSC. The relative concentrations of different network structural units have been determined from the de-convolution of the FTIR spectra. The ac conductivity has been investigated taking the contribution of the electrode-sample interface. The length scales of ion dynamics, such as characteristic mean square displacement and spatial extent of sub-diffusive motion of silver ions have been determined from the ac conductivity and dielectric spectra respectively in the framework of linear response theory. A direct correlation between the ion dynamics and the characteristic length scales and the glass network structure has been established for different compositions of the selenium-tellurite glasses. In Chapter 7 the summary of the thesis is presented. The possible future research in continuation of this work is also highlighted.Research was carried out under the supervision of Prof. Aswini Ghosh of Solid State Division under SPS [School of Physical Sciences]Research was conducted under DST grant and IACS fellowshi

Self-assembling tripeptide based hydrogels and their use in removal of dyes from waste-water

A new class of hydrogelators based on synthetic self-assembling N-terminally Boc-protected tripeptides has been developed. A series of five tripeptides have been synthesized to study their self-assembling behavior in aqueous medium. Three of them form thermoreversible translucent gels at basic pH (pH 11.5–13.5). These hydrogels were characterized by FT-IR spectroscopy, circular dichroism (CD), small angle X-ray diffraction analysis (SAXRD), field-emission scanning electron microscopic (FE-SEM), transmission electron microscopic (TEM) and atomic force microscopic (AFM) studies. These hydrogels can be potentially utilized for the treatment of waste-water and the organic dyes (Rhodamine B, Reactive Blue 4 and Direct Red 80) that are widely used in textile industries can be efficiently removed. Moreover, peptide gelators can be recovered very easily just by changing the pH of the medium

Tetrapeptide-based hydrogels: for encapsulation and slow release of an anticancer drug at physiological pH

Here, we report two synthetic oligopeptide-based, thermoreversible, pH-sensitive hydrogels. In gel phase, these self-assembling tetrapeptides form a long interconnected nanofibrilar network structure, as is evident from various microscopic techniques, including field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM). FTIR, circular dichroism, and wide angle X-ray diffraction (WAXD) favor an antiparallel beta-sheet structure of these gelators in the gel state. Finally, these hydrogels have been utilized for entrapment and slow release of an anticancer drug doxorubicin at physiological pH, promising their future application as a drug delivery vehicle

Pentapeptide Based Organogels: The Role of Adjacently Located Phenylalanine Residues in Gel Formation

A terminally protected self-assembling pentapeptide Boc-Leu(1)-Val(2)-Phe(3)-Phe(4)-Ala(5)-OMe 1 bearing sequence similarity with Ab17–21 (the fragment 17–21 of the amyloid b-peptide Ab42) forms thermoreversible transparent gels in various organic solvents including benzene, toluene, m-xylene and 1,2-dichlorobenzene. A series of its variants have been synthesized in order to study the role of adjacently located phenylalanine residues and the protecting groups for gelation in different organic solvents. Replacement of any of the Phe residues of the Phe-Phe segment with any other hydrophobic a-amino acid residue drastically changes the gel forming properties indicating that both Phe residues have an important role in gel formation. These gels are characterised using field emission scaning electron microscopy (FE-SEM), transmission electron microscopy (TEM), FT-IR and wide angle X-ray scattering (WAXS) studies. WAXS studies of the peptide 1–benzene gel indicate that p–p interaction is responsible for gel formation and it reveals the necessity of the Phe residues in gel formation. Transmission electron microscopy (TEM) of the gels reveals a nanofibrillar morphology, which is obtained from the self-assembled gelators in the gel phase. These gels bind with a physiological dye, Congo red, and show a green birefringence under cross polarizers, which is a characteristic feature of amyloid fibrils

Synthesis of multiple shaped gold nanoparticles using wet chemical method by different dendritic peptides at room temperature

Gold nanoparticles of various shapes including pentagonal, hexagonal, prismatic, branched (multipods), spherical and oval have been prepared by using different generations of peptidic dendrons as templates at room temperature without adding any external reducing or stabilizing agents. Each peptide based dendron molecule (G1, G2 or G3) contains a redox active tyrosine (Tyr) moiety and a free –NH<SUB>2</SUB> group at the N-terminus and as a result of that each peptide-dendron molecule can be used to reduce AuCl<SUB>4</SUB><SUP>-</SUP> to Au<SUP>0</SUP> and stabilize the nascent gold nanoparticles (GNPs) by the NH<SUB>2</SUB>group present in the molecule at room temperature. Not only the shapes but also the sizes of these particles can be tuned by using this chemical methodology involving different peptidic dendrons in water-methanol (4:1) at pH 11. The first generation dendritic peptide produces various shaped GNPs, while the second-generation peptide-dendron molecule leads to the exclusive formation of hexagonal gold nanoparticles and the third generation dendritic peptide gives rise to branched nanoparticles at a certain dendron concentration (5.88 × 10<SUP>-6</SUP>M). In this procedure no external reducing agents or stabilizing agents nor relatively high temperature are required to produce various anisotropic gold nanoparticles. Nanoparticles with different shapes exhibit their characteristic surface plasmon resonance peaks. TEM images vividly demonstrate the specific morphology of gold nanoparticles with different shapes obtained by using different generations of peptide-based dendrons. Corresponding dark field luminescence spectra provide an insight into the shape dependence of the optical properties

The as-prepared gold cluster-based fluorescent sensor for the selective detection of As<SUP>III</SUP> ions in aqueous solution

Water-soluble fluorescent gold clusters (AuCs) have been successfully synthesized by a wet-chemical approach at room temperature using a dipeptide l-cysteinyl-l-cysteine. We have followed the core-etching mechanism for the synthesis of the gold clusters. Clusters show the excitation maximum at 300 nm and the emission maximum at 410 nm. These gold clusters show interesting fluorescent properties including large Stoke's shift (110 nm), with a quantum yield of 41.3%, and photochemical stability. Transmission electron microscopic analysis shows that most of these particles are &#60;1.5 nm. These clusters have been applied successfully to develop the new fluorescent sensor for the selective and ultra-sensitive detection of As(III) ions in the presence of other bivalent and trivalent metal ions in aqueous solution with a lower detection limit of 53.7 nM and this is far below the permissible limit (133 nM) of arsenic in drinking water permitted by WHO and USEPA. These gold clusters also show semiconducting behavior