Development of validated stability indicating assay method for simultaneous estimation of metformin hydrochloride and vildagliptin by RP-HPLC.

A simple, precise and stability-indicating HPLC method was developed and validated for the simultaneous determination of metformin hydrochloride (MET) and vildagliptin (VLG) in pharmaceutical dosage forms. The method involves use of easily available inexpensive laboratory reagents. The separation was achieved on Grace Cyano column (250 mm×4.6 mm) 5 µm with isocratic flow. The mobile phase was pumped at a flow rate of 1.0 mL/min, consisted of 25 mM ammonium bicarbonate buffer and acetonitrile (65:35, v/v). The UV detection was carried out at 207 nm. A linear response was observed over the concentration range of 25-125 µg/mL for MET and 50-250 µg/mL for VLG respectively. Limit of detection and limit of quantification for MET were 0.36 µg/mL and 1.22 µg/mL, and for VLG were 0.75 µg/mL and 2.51 µg/mL respectively. The method was successfully validated in accordance to ICH guidelines acceptance criteria for specificity, linearity, accuracy, precision, robustness, and system suitability. Individual drugs (MET and VLG) were exposed to thermal, photolytic, hydrolytic and oxidative stress conditions. The resultant stressed samples were analyzed by the proposed method. The method gave high resolution among the degradation products and the analytes. The peak purity of analyte peak in the stressed samples was confirmed by photo diode array detector. The proposed method was successfully applied for the quantitative analysis of MET and VLG in tablet dosage form, which will help to improve quality control and contribute to stability studies of pharmaceutical tablets containing these drugs.

Imaging characteristics of common suprasellar lesions with emphasis on MRI findings.

Suprasellar masses are varied in aetiology and can present diagnostic problems for a radiologist. Magnetic resonance imaging (MRI) has largely replaced computed tomography (CT) as a diagnostic tool for these lesions, although CT can provide complementary information in some conditions. In this article, we review imaging features of common suprasellar lesions with emphasis on MRI features.

Preparation and characterization of Eu(3+) doped powder spinel phosphors (MgAl(1.8)Y(0.2-x)O(4)).

The photoluminescence (PL) studies of powder phosphors are under rigorous study in view of the applications they have in the field of technology. Different methods are available for the preparation of rare earth ions doped in different host environment of powder phosphors. In the present work, a novel route known as sol-gel technique is employed to prepare spinel phosphor MgAl(1.8)Y(0.2-x)O(4):Eu(x) (x = 2-6 mol%). Then the studies have been carried out to optimize the dopant concentration in the host lattice with the help of photoluminescence spectra. These phosphors have displayed bright red color under UV source. The emission intensities were determined and the relative fluorescence intensities have been estimated. The richness of the red color has been verified by determining their chromaticity coordinates (X, Y) from the CIE standard charts. With the help of XRD, electron spin resonance (ESR), and photo-acoustic (PA) spectra of the samples prepared are also used for the confirmity of the host and analyzing of the data.

Clinical comparison of ocular blood flow tonometer, Tonopen, and Goldmann applanation tonometer for measuring intraocular pressure in postkeratoplasty eyes.

PURPOSE: Intraocular pressure (IOP) measurements vary with different tonometers in irregular corneas. The purpose of our study was to determine the comparability of the ocular blood flow tonometer (OBF) and Tonopen with the Goldmann applanation tonometer (GAT) in measuring IOP in post-keratoplasty eyes. METHODS: The IOP was measured using the OBF tonometer, GAT, and Tonopen in 69 post-keratoplasty eyes by two observers. The same instruments were used, and the sequence of measurements was randomized. Pachymetry to measure corneal thickness was done in all patients. RESULTS: Interobserver variation for IOP measured with GAT was statistically significant ( p = 0.039). Two-way analysis of variance (ANOVA), however, did not demonstrate any statistical difference between measurements with the three tonometers and two observers. Corneal thickness did not appear to have an effect on measurements with any of the tonometers. CONCLUSION: There was no significant difference in the overall accuracy of the OBF tonometer over the Tonopen versus the GAT. The OBF tonometer can be a useful alternative in measuring IOP in post-keratoplasty eyes.

Photochemical E (trans)-->Z (cis) isomerization in substituted 1-naphthylacrylates.

Substituted naphthylacrylates, 1-3, not showing rotamerism have been synthesized with a view to study photochemical E (trans)-->Z (cis) isomerization. Photostationary state composition of the isomers upon direct excitation, triplet sensitized isomerization, quantum yield of isomerization, and steady state and time-resolved fluorescence behavior have been studied for these naphthylacrylates. The direct excitations of the compounds yield high Z (approximately 80%) isomer composition, whereas the triplet sensitization results in less Z (approximately 20%) isomer composition. This indicates that the singlet pathway is very efficient in converting the E isomer to the Z isomer. The naphthylacrylates 1 and 2 exhibit structured fluorescence at room temperature in hexane and upon changing the solvent to CH3CN; the structure of the fluorescence is lost, indicating that the singlet excited-state develops a polar character in a polar environment. The polar nature of the singlet excited state becomes more clear in the case of 3 from its fluorescence solvatochromism. The naphthylacrylates did not exhibit excitation wavelength-dependent fluorescence at room temperature suggesting that the ground state conformers (rotamers) are not involved. Fluorescence lifetimes measured for these compounds displayed biexponential behavior, which is explained using a two-state model.

Fatal heroin body packing.

The deaths of 10 heroin body packers are reported and contrasted to those of cocaine body packers. Only one was a woman, and all were traveling to or from Colombia. Drug packets deteriorated in the gastrointestinal tract and caused the deaths of eight victims. Accomplices removed drug packets from two of these smugglers after death occurred. One died of peritonitis stemming from a small-bowel obstruction caused by the drug packets, and one died from the recreational use of heroin (nasally ingested). The heroin recovered was < or = 881 g, and the drug purity of the contraband in three cases was between 65% and 73%. Blood concentrations of morphine were < 1.0 mg/L in four victims; no morphine was detected in the smuggler who died of peritonitis. However, two victims had blood morphine concentrations of 4.4 mg/L and 6.7 mg/L, respectively, and three had morphine concentrations of 35.8, 39.4, and 52.6 mg/L, respectively. Fatal heroin body packing differs from cocaine body packing in that individuals may have extremely high drug levels in their blood and their accomplices appear to be more likely to abandon them in a remote location after attempting to remove the drug packets after death has occurred.

Positional asphyxiation in adults. A series of 30 cases from the Dade and Broward County Florida Medical Examiner Offices from 1982 to 1990.

Over a 9-year period, 30 cases of positional (or postural) asphyxia were identified in the Dade and Broward County (Florida) Medical Examiner Offices. The victims had an average age of 50.6 years with no significant sex or racial differences as compared with the general medical examiner population. Chronic alcoholism or acute alcohol intoxication was a significant risk factor in 75% of cases and these had an average postmortem ethanol concentration of 0.24 g%. Signs of mechanical asphyxiation (petechiae and/or combined lung weights greater than 900 g) were present in 93% of cases. Victims were commonly (43%) found in a restrictive position producing hyperflexion of the head and neck. Two deaths involved restraint vests ("poseys") in elderly, demented, wheel-chair-confined victims. Scene photographs of the undisturbed decedent are extremely helpful in confirming a suspicion of postional asphyxia.

The major carotenoid pigment of a psychrotrophic Micrococcus roseus strain: purification, structure, and interaction with synthetic membranes.

The major carotenoid pigment of a psychrotrophic Micrococcus roseus strain was purified to homogeneity from methanol extracts of dried cells by reverse-phase liquid chromatography and was designated P-3. On the basis of the UV-visible, infrared, mass, and 1H nuclear magnetic resonance spectra of P-3, it was identified as bisdehydro-beta-carotene-2-carboxylic acid. The pigment interacted with synthetic membranes of phosphatidylcholine and dimyristoyl phosphatidylcholine and stabilized the membranes. These results also indicate that P-3 is different from canthaxanthin, the major carotenoid pigment from a mesophilic M. roseus strain.

Evaluation and identification of dismembered human remains.

On occasion, pathologists are confronted with cases involving dismembered human remains. Such cases present unique and interesting problems of postmortem identification. Four cases involving dismembered human remains are presented here and practical suggestions on how identification can be achieved are provided.

Sudden death due to unsuspected coronary vasculitis.

Coronary artery vasculitis is a well-recognized complication of polyarteritis nodosa and is occasionally seen in other forms of systemic vasculitis. However, involvement of the major epicardial coronary arteries leading to myocardial infarction and death is uncommon. Isolated coronary arteritis is even more rare. We report three cases of sudden death due to myocardial ischemia associated with arteritis of the major coronary arteries. All three decedents were previously healthy young to middle-aged men who had died suddenly after complaints of chest pain and shortness of breath. The autopsy findings and differential diagnoses are presented. Such cases are of particular interest to the medical examiner because of the sudden, unexpected nature of the deaths. An approach to the correct diagnosis is discussed.

Effects of modifications of the retinal beta-ionone ring on archaebacterial sensory rhodopsin I.

Ring desmethyl and acyclic analogues of all-trans retinal were incorporated into the apoprotein of the phototaxis receptor sensory rhodopsin I (SR-I) in Halobacterium halobium membranes. All modified retinals generate SR-I analogue pigments which exhibit "opsin shifts," i.e., their absorption spectra are shifted to longer wavelengths compared with model protonated Schiff bases of the same analogues. Each SR-I pigment analogue exhibits cyclic photochemical reactions as monitored by flash spectroscopy, but the analogue photocycles differ from that of native SR-I by exhibiting pronounced biphasic recovery of flash-induced absorption changes and abnormal flash-induced absorption difference spectra. Despite perturbations in the photochemical properties, the SR-I pigment analogues are capable of both attractant (single photon) and repellent (two photon) phototaxis signaling in cells. Our interpretation is that the hydrophobic ring substituents interact with the binding pocket to maintain the correct configuration for native SR-I absorption and photochemistry, but these interactions are not essential for the physiological function of SR-I as a dual attractant/repellent phototaxis receptor. These results support the conclusion emerging from several studies that the photoactivation process that triggers the conformation changes of SR-I and the related proton pump bacteriorhodopsin is conserved despite the different biological functions of their photoactivation.

Survival time in gunshot and stab wound victims.

Forensic pathologists are often asked to estimate postinjury survival time and to render an opinion on the probable extent of physical activity following fatal injury. To study this question, the case files of the Dade County Medical Examiner's Office were reviewed. The year 1983 was chosen arbitrarily for this study and all the autopsy reports of gunshot or stab wound victims whose survival period satisfied criteria established for this study were reviewed. The data were compared to those from a similar study done in 1961. In addition, this study noted the presence and influence of drugs or alcohol on the cause of death and the postinjury survival time.

Death from pool chlorine--an unusual case.

A tank truck containing bulk pool chlorinating solution overturned. A man was trapped beneath the truck, and a ruptured seam in the tank released a continuous flow of sodium hypochlorite over him. He survived for 10 min as the caustic solution extensively eroded soft tissue exposed to the chemical flow.

The forensic significance of conjunctival petechiae.

Conjunctival petechiae were mentioned in 227 (4.5%) of 5,000 consecutive autopsy reports of the Dade County Medical Examiner Department. They were most frequently observed in those who had died natural deaths (particularly due to cardiovascular disease), followed by those who had died from asphyxia, head injury, and central nervous system disorders. The incidence of conjunctival petechiae in victims of homicidal asphyxiation was 78%. These data suggest that conjunctival petechiae most often are the result of hypoxia coupled with an acute increase in cephalic vascular pressure. The latter factor may be the consequence of mechanical vascular obstruction or acute right heart failure.

Patterned injury and its evidentiary value.

A rape-homicide victim was stomped by her assailant leaving a unique patterned injury on her scalp. Two methods were used to subsequently match the patterned injury on her scalp to the pattern on the shoe of the assailant that was found at the crime scene.

Female homicide-suicide perpetrators: a controlled study.

The record files of the Dade County Medical Examiner Department were reviewed and 133 homicide-suicides were identified. Of these, ten (or 7.5%) were female perpetrated. The chart data of these 10 female homicide-suicide perpetrators, chart data of 50 female homicide-suicide victims, and 50 female individual suicides systematically selected as controls were tabulated using a standardized instrument. The results were analyzed for differences using simple statistical methods. The comparisons revealed that female homicide-suicide perpetrators were more likely than female homicide-suicide victims to live in mobile homes, kill their lover or ex-lover, have their crime accidentally discovered, leave a suicide note, kill on a weekend, and be depressed, but are less likely than female homicide-suicide victims to live with a spouse. Additionally, female homicide-suicide perpetrators were more likely than individual female suicides to live in mobile homes but less likely to live alone and to be depressed.