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Biomedical subjects

R Suryanarayanan

Publications and source records attributed to R Suryanarayanan.

At least 19 recordsLinked to original sources
PubMed2007

Homeopathic Arnica montana for post-tonsillectomy analgesia: a randomised placebo control trial.

OBJECTIVE: To evaluate the efficacy of Homeopathic Arnica in reducing the morbidity following tonsillectomy. METHODS: Randomised double blind, placebo controlled trial at a tertiary referral centre. 190 patients over the age of 18 undergoing tonsillectomy were randomised into intervention and control groups receiving either Arnica 30c or identical placebo, 2 tablets 6 times in the first post-operative day and then 2 tablets twice a day for the next 7 days. The primary outcome measure was the change in pain scores (visual analogue scale) recorded by the patient on a questionnaire over 14 days post-operatively; Secondary outcome measures were: analgesia consumption, visits to the GP or hospital, antibiotic usage, the day on which their swallowing returned to normal and the day on which they returned to work. RESULTS: 111 (58.4%) completed questionnaires were available for analysis. The Arnica group had a significantly larger drop in pain score from day 1 to day 14 (28.3) compared to the placebo group (23.8) with p < 0.05. The two groups did not differ significantly on analgesic consumption or any of the other secondary outcome measures (number of post-operative visits to GP, use of antibiotics and secondary haemorrhage readmissions). CONCLUSION: The results of this trial suggest that Arnica montana given after tonsillectomy provides a small, but statistically significant, decrease in pain scores compared to placebo.

Adult↗
PubMed2005

Metastatic carcinoma mimicking a facial nerve schwannoma: the role of computerized tomography in diagnosis.

Secondary deposits in the temporal bone are uncommon but well recognized. Such tumours may involve the facial nerve by direct extension of the destructive process into the fallopian canal. We present a rare case of metastasis from a breast carcinoma in the facial nerve itself, involving the nerve in the internal acoustic meatus with extension into the labyrinthine segment, the first genu and into the middle-ear segment. The rest of the temporal bone was not involved. The lesion resembled a facial schwannoma on a routine magnetic resonance (MR) image. The diagnosis was confirmed after a post-operative computed tomography (CT) scan showed another separate secondary deposit in the basisphenoid. Histology was consistent with secondary tumour from a breast carcinoma. The case highlights the importance of keeping a high degree of suspicion for metastatic tumours in patients with a previous history of malignancy and the usefulness of CT scan in the evaluation of such cases.

Breast Neoplasms↗
PubMed2004

Field-induced ferromagnetic metallic state in the bilayer manganite (La0.4Pr0.6)1.2Sr1.8Mn2O7, probed by neutron scattering.

The bilayer manganite La1.2Sr1.8Mn2O7 exhibits a phase transition from a paramagnetic insulating (PI) to a ferromagnetic metallic (FM) state with a colossal magnetoresistance (CMR) effect. Upon 60% Pr substitution, magnetic order and PI to FM transition are suppressed. Application of a moderate magnetic field restores an FM state with a CMR effect. Neutron scattering by a single crystal of (La0.4Pr0.6)1.2Sr1.8Mn2O7, under a magnetic field of 5 T, has revealed a long-range and homogeneous ferromagnetic order. In the PI phase, under zero field, correlated lattice polarons have been detected. At 28 K, under 5 T, the spin wave dispersion curve determines an in-plane isotropic spin wave stiffness constant of 146 meV A(2). So the magnetic field not only generates a homogeneous ferromagnetic ground state, but also restores a magnetic coupling characteristic of FM CMR manganites.

Journal Article↗
PubMed2004

Long-term results of gentamicin inner ear perfusion in Ménière's disease.

Chemical perfusion of the inner ear is an increasingly popular treatment for Ménière's disease. The authors report on the long-term results of 22 patients treated with gentamicin delivered via a round window micro-catheter. Patients with Ménière's disease underwent continuous, low dose (10 mg/ml) gentamicin infusion at 5 microlitre per hour for 10 days, through a micro-catheter placed into the round window niche. Vertigo was controlled in 95 per cent, whilst preserving hearing in 77 per cent. Hearing improved in three patients. Three patients with pre-operative serviceable hearing (PTA < 50 db) demonstrated reduced hearing; two patients with pre-operative non-serviceable hearing developed a dead ear. Tinnitus and aural fullness remained unchanged or improved in 86 per cent and 68 per cent respectively. Long-term vertigo control can be achieved using low dose gentamicin, whilst preserving hearing and vestibular function in the majority of patients. This procedure appears to stabilize the vestibular function, enhancing the chance of effective vestibular rehabilitation.

Administration, Topical↗
PubMed2003

Field-induced ferromagnetic metallic state of bilayer manganite (La0.4Pr0.6)1.2Sr1.8Mn2O7: a polarized neutron diffraction study.

Unpolarized and polarized neutron diffraction measurements have been carried out on the bilayer manganite (La0.4Pr0.6)1.2Sr1.8Mn2O7 which undergoes simultaneous semiconductor-metal paraferromagnetic transitions under magnetic field. Maximum entropy magnetization density reconstruction and multipole refinement on flipping ratios evidence the existence of two distinct field-induced states. The field-induced ferromagnetic state where the field is parallel to the c axis is characterized by the presence of magnetic moment on the Sr site of 0.48(2)mu(B), due to the Pr substitution. It also shows a high population of the d3(z(2)-r(2)) orbitals of Mn3+. For the field-induced state where the field is parallel to the a or b axes no magnetization density was found at the Sr site and the dx(2)(-y(2)) orbital is slightly more populated than the d3(z(2)-r(2)) one.

Journal Article↗
PubMed2002

X-ray powder diffractometric method for quantitation of crystalline drug in microparticulate systems. I. Microspheres.

Ethylcellulose microspheres containing tolnaftate (I) were prepared by the emulsion-solvent evaporation technique. An X-ray powder diffractometric method was developed to quantify the content of crystalline I in these microspheres. X-ray lines of I with d-spacings of 5.5 and 4.2 A were chosen for the quantitative analyses. Physical mixtures containing various weight fractions of I and blank (empty) microspheres were prepared and lithium fluoride (20% w/w) was added as the internal standard. The 5.5 and 4.3 A lines of I and the 2.3 A line of lithium fluoride were used for the quantitative analysis. A plot of the intensity ratio (intensity of the 5.5 A line of I/intensity of 2.3 A line of lithium fluoride) as a function of the weight percent of I in the mixture, resulted in a straight line. The crystalline content of I in the tolnaftate-loaded microspheres was determined using this standard curve. A second independent determination of the content of I was possible from the intensities of the 4.3 A line. The enthalpy of fusion of I, determined by differential scanning calorimetry (DSC), was also used as a measure of the crystalline content of I in the microspheres. The X-ray and DSC methods measure the content of crystalline I in the microspheres at room temperature ( approximately 25 degrees C) and at the melting point of I (111 degrees C), respectively. The total content of I in the microspheres was determined by HPLC. The DSC and X-ray results indicated that a substantial fraction of the incorporated I was dissolved in the ethylcellulose matrix.

Cellulose↗
PubMed2002

Long term tissue response to titanium coated with diamond like carbon.

Diamond like carbon (DLC) coatings were deposited on to Ti substrates by plasma enhanced chemical vapor deposition technique. Ti and DLC/Ti samples were implanted in skeletal muscle of rabbits. The samples were explanted after 1, 3, 6 and 12 months and the tissue-cell interaction was studied. Our data indicate both DLC/Ti and bare Ti to be compatible with skeletal muscle.

Animals↗
PubMed2002

Quantitation of platelet adhesion to Ti and DLC-coated Ti in vitro using (125)I-labeled platelets.

Measurement of platelet adhesion in vitro is a good indicator of its reactivity to implant devices in vivo. Platelets were labeled with I-125 without affecting its normal morphology and function and the labeled platelets were suspended in platelet poor plasma and exposed to Ti and diamond like carbon-coated (DLC) Ti discs, under dynamic conditions, using a parallel plate flow chamber. The test materials were washed, dried, exposed to a phosphor screen and scanned to get the images. The number of platelets that adhered to Ti was found to be higher than those that adhered to DLC coated Ti sample, irrespective of the shear stress which was varied between 2 and 16 dynes/cm(2).

Blood Platelets↗
PubMed2002

A method for providing a unilateral pressure dressing in the neck.

The application of a reliable adequate pressure dressing to one side of the neck has always proved difficult, because of the risk of occluding the airway and the vasculature. We describe a method of maintaining well-localized pressure to one side of the neck without undue pressure on the vasculature and the airway by using a stiff cervical collar. This method was used successfully in the conservative management of neck haematoma in two patients.

Aged↗
PubMed2002

In vitro cytocompatibility studies of Diamond Like Carbon coatings on titanium.

Diamond like carbon (DLC) films were deposited on to titanium (Ti) substrates by Plasma Enhanced Chemical Vapour Deposition (PECVD) process. The quality of the films were checked by Raman spectra and nano-hardness tests. The cytocompatibility of titanium and DLC coated titanium were studied using continuous cell lines of mouse fibroblast cells ( L-929), Human Osteoblast cells (HOS) and primary human umbilical cord vein endothelial cells (HUVEC). The cellular responses to the materials were assessed both quantitatively and qualitatively. The adhesion and spreading of cells on materials were compared using Ti as a control. Present study indicates an improved cytocompatibility of DLC coated Ti in comparison to bare Ti.

Animals↗
PubMed2001

Investigation of solid-state reactions using variable temperature X-ray powder diffractrometry. I. Aspartame hemihydrate.

PURPOSE: The object of this study was to demonstrate the applicability of variable temperature X-ray powder diffractometry (XRD) to investigate solid-state reactions using aspartame as a model compound. METHODS: Aspartame exists as a hemihydrate (ASH) under ambient conditions and converts to aspartame anhydrate (ASA) at approximately 130 degrees C. ASA on further heating to approximately 180 degrees C undergoes decomposition (intramolecular cyclization) to form a diketopiperazine derivative (DKP). The dehydration as well as the decomposition kinetics were studied isothermally at several temperatures. The unique feature of this technique is that it permits simultaneous quantification of the reactant as well as the product. RESULTS: While the dehydration of ASH appeared to follow first-order kinetics, the cyclization of ASA was a nucleation controlled process. The rate constants were obtained at various temperatures, which permitted the calculation of the activation energies of dehydration and cyclization from the Arrhenius plots. The activation energy of dehydration was also calculated according to the method described by Ng (Aust. J. Chem., 28:1169-1178, 1975) and the two values were in good agreement. CONCLUSIONS: The study demonstrates that XRD is an excellent complement to thermal analysis and provides direct information about the solid-states of various reaction phases.

Algorithms↗
PubMed2001

Phase transitions of glycine in frozen aqueous solutions and during freeze-drying.

PURPOSE: To study the solid-state and phase transitions of glycine, (i) in frozen aqueous solutions, and (ii) during freeze-drying. METHODS: X-ray powder diffractometry (XRD) and differential scanning calorimetry (DSC) were used to analyze the frozen systems. In situ freeze-drying in the sample chamber of the diffractometer enabled characterization of phase transitions during freeze-drying. RESULTS: Transitions in frozen systems. Rapid (20 degrees C/min) or slow (2 degrees C/min) cooling of aqueous solutions of glycine (15% w/w) to -70 degrees C resulted in crystallization of beta-glycine. Annealing at -10 degrees C led to an increase in the amount of the crystalline phase. When quench-cooled by immersing in liquid nitrogen, glycine formed an amorphous freeze-concentrate. On heating, crystallization of an unidentified phase of glycine occurred at approximately -65 degrees C which disappeared at approximately -55 degrees C, and the peaks of beta-glycine appeared. Annealing caused a transition of beta- to the -gamma- form. The extent of this conversion was a function of the annealing temperature. Slower cooling rates and annealing in frozen solutions increased the crystalline beta-glycine content in the Iyophile. Freeze-drying of quench-cooled solutions led to the formation of gamma-glycine during primary drying resulting in a lyophile consisting of a mixture of beta- and -gamma-glycine. The primary drying temperature as well as the initial solute concentration significantly influenced the solidstate of freeze-dried glycine only in quench-cooled systems. CONCLUSIONS: The cooling rate, annealing conditions and the primary drying temperature influenced the solid-state composition of freeze-dried glycine.

Calorimetry, Differential Scanning↗
PubMed2000

In situ dehydration of carbamazepine dihydrate: a novel technique to prepare amorphous anhydrous carbamazepine.

The purposes of this project were to prepare amorphous carbamazepine by dehydration of crystalline carbamazepine dihydrate, and to study the kinetics of crystallization of the prepared amorphous phase. Amorphous carbamazepine was formed and characterized in situ in the sample chamber of a differential scanning calorimeter (DSC), a thermogravimetric analyzer (TGA), and a variable temperature x-ray powder diffractometer (VTXRD). It has a glass transition temperature of 56 degrees C and it is a relatively strong glass with a strength parameter of 37. The kinetics of its crystallization were followed by isothermal XRD, under a controlled water vapor pressure of 23 Torr. The crystallization kinetics are best described by the three-dimensional nuclear growth model with rate constants of 0.014, 0.021, and 0.032 min-1 at 45, 50, and 55 degrees C, respectively. When the Arrhenius equation was used, the activation energy of crystallization was calculated to be 74 kJ/mol in the presence of water vapor (23 Torr). On the basis of the Kissinger plot, the activation energy of crystallization in the absence of water vapor (0 Torr water vapor pressure) was determined to be 157 kJ/mol. Dehydration of the dihydrate is a novel method to prepare amorphous carbamazepine; in comparison with other methods, it is a relatively gentle and effective technique.

Algorithms↗
PubMed1999

Solid-state phase transitions of AG337, an antitumor agent.

The object of this investigation was to perform detailed solid-state characterization studies on the different solid forms of AG337 and to determine the conditions of their interconversions. Solid-state characterization was done using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), hot stage microscopy, Karl Fischer titrimetry, ambient and variable temperature X-ray powder diffractometry (XRD) and TGA coupled with FTIR (TGA/FTIR). In addition to five polymorphic forms of the anhydrate (I alpha to I epsilon), a hemihydrate (C14H12N4OS.2HCl.0.5H2O, II), a monohydrate (C14H12N4OS.2HCl.H2O; III), as well as a dihydrate (C14H12N4OS.2HCl.2H2O; IV) were identified. The 'as is' anhydrate, I alpha, resisted water uptake until stored at 98% RH (room temperature), where it transformed directly to IV, II and III transformed to IV at RH values > or = 7.6 and 84% respectively. Heating II and III to 130 degrees C in the variable temperature XRD resulted in the formation of I beta and I gamma respectively. On the other hand, I delta and I epsilon were obtained when II and III were respectively stored at 60 degrees C under vacuum. Variable temperature XRD, by providing information about the solid-state as a function of temperature, assisted in the interpretation of the DSC and TGA results. TGA/FTIR provided direct evidence that the thermal events observed in the temperature ranges of 25-150 degrees C and 200-250 degrees C were due to loss of water and loss of hydrogen chloride respectively. In addition to the conventional analytical techniques such as XRD, DSC, TGA and KFT, two other techniques, (variable temperature XRD and TGA/FTIR), were very useful in these solid-state characterization studies.

Antimetabolites, Antineoplastic↗
PubMed1998

Characterization of frozen aqueous solutions by low temperature X-ray powder diffractometry.

PURPOSE: A low temperature X-ray powder diffractometric (XRD) technique has been developed which permits in situ characterization of the solid-state of solutes in frozen aqueous solutions. METHODS: A variable temperature stage, with a working temperature range of -190 to 300 degrees C, was attached to a wide-angle XRD. The stage was calibrated with a sodium chloride-water binary system. RESULTS: When aqueous nafcillin sodium solution (22% w/w) was frozen, eutectic crystallization of the solute was not observed. However, annealing at -4 degrees C, caused crystallization of the solute. With increasing annealing time, there was a progressive increase in the crystallinity of the solute. Studies were carried out with sodium nafcillin solutions ranging in concentration from 20 to 50% w/w. The solid-state of the phase crystallizing from solution was independent of the solute concentration. Next, solutions of mono- and disodium hydrogen phosphate were individually frozen. Only the latter crystallized as the dodecahydrate (Na2HPO4.12H2O). However when an aqueous buffer mixture of mono- and disodium hydrogen phosphate was frozen, the former inhibited the crystallization of the latter. CONCLUSIONS: Since freezing of solutions is the first step in lyophilization, the XRD technique can provide a mechanistic understanding of the alterations in solid-state that occur during freeze-drying. DSC has so far been the technique of choice to study frozen systems. The advantage of XRD is that it not only permits unambiguous identification of the crystalline solid phase(s), but it also provides information about the degree of crystallinity. While overlapping thermal events are difficult to interpret in DSC, XRD does not suffer from such a limitation.

Freezing↗