Validated spectrophotometric determination of maduramicin ammonium using three charge transfer complexation reactions.

Direct spectrophotometric determination of Maduramicin ammonium (MAD) represents an analytical challenge since it is a weak UV-absorbing and lacking a strong chromophore. This work represents the first spectrophotometric determination of MAD as no direct spectrophotometric or colorimetric determination methods for MAD are available in the literature. The present study illustrates the development of three simple, rapid and inexpensive colorimetric methods for the routine quality control analysis of MAD based on the formation of colored charge transfer complexes with three electron acceptors namely p-chloranilic acid (p-CA), 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and picric acid (PA). The color products of MAD with p-CA, DDQ and PA were measured at 519, 588 and 405nm respectively. The proposed methods were validated in terms of linearity, ranges, precision, accuracy, robustness and limits of detection and quantification. MAD was effectively determined over concentration ranges of 100-1000, 25-250 and 30-150µg/mL using p-CA, DDQ and PA, respectively with good linearity as shown by the values of correlation coefficients not less than 0.9991. The developed methods were successfully implemented in the assay of MAD powder pharmaceutical formulation for veterinary use.

Validated spectrophotometric and chromatographic methods for simultaneous determination of ketorolac tromethamine and phenylephrine hydrochloride.

This work describes five simple and reliable spectrophotometric and chromatographic methods for analysis of the binary mixture of ketorolac tromethamine (KTR) and phenylephrine hydrochloride (PHE). Method I is based on the use of conventional Amax and derivative spectrophotometry with the zero-crossing technique where KTR was determined using its Amax and (1)D amplitudes at 323 and 341nm respectively, while PHE was determined by measuring the (1)D amplitudes at 248.5nm. Method II involves the application of the ratio spectra derivative spectrophotometry. For KTR, 12µg/mL PHE was used as a divisor and the (1)DD amplitudes at 265nm were plotted against KTR concentrations; while - by using 4µg/mL KTR as divisor - the (1)DD amplitudes at 243.5nm were found proportional to PHE concentrations. Method III depends on ratio-difference measurement where the peak to trough amplitudes between 260 and 284nm were measured and correlated to KTR concentration. Similarly, the peak to trough amplitudes between 235 and 260nm in the PHE ratio spectra were recorded. For method IV, the two compounds were separated using Merck HPTLC sheets of silica gel 60 F254 and a mobile phase composed of chloroform/methanol/ammonia (70:30:2, by volume) followed by densitometric measurement of KTR and PHE spots at 320 and 278nm respectively. Method V depends on HPLC-DAD. Effective chromatographic separation was achieved using Zorbax eclipse plus C8 column (4.6×250mm, 5µm) with a mobile phase consisting of 0.05M o-phosphoric acid and acetonitrile (50:50, by volume) at a flow rate 1mL/min and detection at 313 and 274nm for KTR and PHE respectively. Analytical performance of the developed methods was statistically validated according to the ICH guidelines with respect to linearity, ranges, precision, accuracy, detection and quantification limits. The validated spectrophotometric and chromatographic methods were successfully applied to the simultaneous analysis of KTR and PHE in synthetic mixtures of different proportions and laboratory-made ophthalmic solution.

Beyond RGD: virus interactions with integrins.

Viruses successfully infect host cells by initially binding to the surfaces of the cells, followed by an intricate entry process. As multifunctional heterodimeric cell-surface receptor molecules, integrins have been shown to usefully serve as entry receptors for a plethora of viruses. However, the exact role(s) of integrins in viral pathogen internalization has yet to be elaborately described. Notably, several viruses harbor integrin-recognition motifs displayed on viral envelope/capsid-associated proteins. The most common of these motifs is the minimal peptide sequence for binding integrins, RGD (Arg-Gly-Asp), which is known for its role in virus infection via its ability to interact with over half of the more than 20 known integrins. Not all virus-integrin interactions are RGD-dependent, however. Non-RGD-binding integrins have also been shown to effectively promote virus entry and infection as well. Such virus-integrin binding is shown to facilitate adhesion, cytoskeleton rearrangement, integrin activation, and increased intracellular signaling. Also, we have attempted to discuss the role of carbohydrate moieties in virus interactions with receptor-like host cell surface integrins that drive the process of internalization. As much as possible, this article examines the published literature regarding the role of integrins in terms of virus infection and virus-encoded glycosylated proteins that mediate interactions with integrins, and it explores the idea of targeting these receptors as a therapeutic treatment option.

Initial experience using robot- assisted transaxillary thyroidectomy for Graves' disease.

INTRODUCTION: Graves' disease is the most common form of hyperthyroidism and surgery to remove the thyroid gland is a common treatment option for many of these patients. Interestingly, due to the enlarged gland size, their high vascularity, and the difficulty to control bleeding, many authors feel that Graves' disease remains a contraindication to current endoscopic techniques. We hypothesize that performing robotic subtotal thyroidectomy in Graves' disease settings could overcome the limitations of conventional endoscopic surgeries in the surgical management of this challenging thyroid disease. METHODS: Prospective study in an academic hospital. RESULTS: Sixty-seven patients had robotic transaxillary thyroidectomy within a year. Of these, five cases (7%) were done for Graves' disease. There were three females and two males (mean age, 36 years). There were no conversions to laparoscopic or open surgery. The mean (SD) thyroid volume was 16.6 (3.2) ml. The mean (SD) operative time was 159 (17.8)min and docking time was 81 (20)min. Mean blood loss was 18 mL. All patients were discharged home in 24h. There were no perioperative or postoperative complications. There was no evidence of postoperative vocal cord palsy or paresis. CONCLUSIONS: We showed that robotic transaxillary thyroidectomy is feasible and can be safe and effective in patients with Graves' disease. To our knowledge, this is the first article describing this approach for Graves' disease. These findings, however, warrant additional investigation within future prospective clinical trials.

A 4-year follow-up of a randomized prospective study comparing transurethral electrovaporization of the prostate with neodymium: YAG laser therapy for treating benign prostatic hyperplasia.

OBJECTIVE: To compare the safety, efficacy and durability of neodymium (Nd):YAG laser prostatectomy with transurethral electrovaporization of the prostate (TUVP) for treating benign prostatic hyperplasia (BPH). PATIENTS AND METHODS: From March 1995 to March 1997, 180 patients with bladder outlet obstruction secondary to BPH were randomized equally either to Nd:YAG laser therapy or TUVP. Laser therapy combined two different techniques, side-fire coagulation of the lateral lobes and contact vaporization of the median lobe. Before treatment the two groups had a comparable International Prostate Symptom Score (IPSS), quality-of-life score (QoL), maximum urinary flow rate (Qmax), postvoid residual urine volume (PVR), and prostate and adenoma volume. In all, 62 and 78 patients completed the 1, 2, 3 and 4-year follow-up from the laser and TUVP groups, respectively. RESULTS: At each follow-up, the IPSS, QoL, Qmax and PVR were significantly better and more durable in the TUVP than in the laser group. In the TUVP and laser groups respectively, at the 4-year follow-up the mean value of the IPSS was 3.7 vs 11.9, the QoL 1.3 vs 3.1, the Qmax 21.4 vs 13.6 mL/s and the PVR 25.1 vs 64.6 mL (all P < 0.001). The mean prostate and adenoma volume were significantly lower after TUVP than after laser therapy (P < 0.001) at the 1- and 4-year follow-up, with final values of 27.9 vs 35.9 and 11.7 vs 20 mL (both P < 0.001) for the TUVP and laser groups, respectively. Retrograde ejaculation was significantly more common after TUVP (63%) than after laser therapy (18%; P < 0.001). Impotence was reported in 8% of men after TUVP and in none after laser therapy (P = 0.040). The re-operation rate was 12% after TUVP and 38% after laser treatment (P < 0.001). CONCLUSION: These 4-year follow-up results confirm that TUVP is significantly more effective and durable than the Nd:YAG laser for treating BPH. Residual obstructing adenoma was the main cause of failure in the laser group, which reflects the inadequacy of laser therapy for removing the adenoma.

A comparison of topical anaesthesia and retrobulbar block for cataract surgery.

It is possible to remove a cataract and insert an intraocular lens under topical anaesthesia (lignocaine 4% preservative-free eye drops) with a van Lint block. This study was performed to evaluate this anaesthetic technique. Nineteen patients having cataract surgery with topical anaesthesia and a van Lint block were compared with 21 patients who received a retrobulbar block and a van Lint block. There were no significant differences between the two groups in patient characteristics, mean cardiovascular stress of the procedure, experience of pain during the operation or willingness to have the same anaesthetic technique again. Topical anaesthesia with a van Lint block is feasible for cataract surgery and is potentially safer than other regional anaesthetic techniques.

Plasma catecholamines in pulmonary tuberculosis.

Fifty pulmonary tuberculous patients (minimal; moderate and far-advanced), 18 TB-healed persons and 15 healthy control subjects were examined for plasma levels of adrenaline (AD), noradrenaline (NA), dopamine (DA), ACTH and cortisol. The estimated hormones were found to be increased significantly with the severity of the disease suggesting that the stress of infection plays a role in induction of enzymes responsible for catecholamines synthesis with subsequent stimulation of ACTH and cortisol secretion. Noradrenaline appeared the most effective in this respect.

Visual evoked potential latency and contrast sensitivity in patients with posterior chamber intraocular lens implants.

An electrophysiological investigation of visual evoked potential (VEP) latency and contrast sensitivity was performed in a group of 13 patients who had undergone extracapsular cataract surgery with posterior chamber lens implantation. In spite of good postoperative visual acuity, abnormalities were detected in nine of the group (69%). This study suggests that, even with successfully implanted lenses, there may be a reduction in visual function which could be the result of altered transmission through the plastic lenticulus or fibrosis of the posterior lens capsule, and/or subtle changes in retinal architecture, not observed ophthalmoscopically.

Retinal macroaneurysm: natural history and guidelines for treatment.

This report describes the features and clinical significance of retinal macroaneurysm. Two groups can be defined: those with acute aneurysmal decompensation, Group I; and those with chronic aneurysmal decompensation, Group II. Haemorrhage is the main feature of the former group and exudates of the latter. Systemic and local associations are noted, and guidelines for treatment by phototherapy are discussed.

Utility of 2,3-dichloro-5,6-dicyano-p-benzoquinone in assay of codeine, emetine and pilocarpine.

A simple and sensitive spectrophotometric method for the assay of codeine, emetine and pilocarpine is described, based on the interaction of these drugs (as n-electron donors) with 2,3-dichloro-5,6-dicyano-p-benzoquinone (as pi -acceptor) to give a highly coloured radical anion which exhibits maximum absorption at 460 nm. Formation of the radical anion has been established by electron spin resonance measurements. Beer's law is obeyed for the alkaloids investigated. The assay results are in accord with pharmacopoeial assay results. The procedure is sufficiently sensitive to permit unit dose assay of the individual alkaloids in pharmaceutical formulations.

Colorimetric determination of two fenamates in capsule dosage form.

The colorimetric determination of mefenamic acid and flufenamic acid with potassium ferricyanide in sodium hydroxide medium is described. The orange product is measured at 464 nm. The molar absorptivities are 1.9 x 10(3) and 2.9 x 10(3) 1.mole(-1).cm(-1) for mefenamic acid and flufenamic acid, respectively. The method has been applied successfully to the determination of these drugs in capsules.

Quantitation of indomethacin, naproxen, and ibuprofen in pharmaceutical dosage forms by first and second derivative ultraviolet spectrometry.

First and second derivative ultraviolet spectrometric methods are described for the estimation of indomethacin, naproxen, and ibuprofen in pharmaceutical dosage forms. The proposed methods permit the rapid, precise, and accurate determination of indomethacin capsules BP, naproxen capsules, and ibuprofen tablets BP. Matrix interference is successfully corrected. The results obtained by first and second derivative techniques are in accord with those obtained by the official assay method.

Spectrophotometric determination of phenothiazines, tetracyclines and chloramphenicol with sodium cobaltinitrite.

A spectrophotometric method for determining some phenothiazines, some tetracyclines and chloramphenicol is described. Chlorpromazine hydrochloride, promazine hydrochloride, promethazine hydrochloride, perphenazine and fluphenazine hydrochloride are reacted with sodium cobaltinitrite in phosphoric acid. The red colour developed is measured at 530, 513, 515, 530 and 500 nm, respectively. Tetracycline hydrochloride, oxytetracycline hydrochloride, chlortetracycline hydrochloride, doxycycline hyclate and demeclocycline hydrochloride are reacted with the reagent in aqueous acetic acid. The yellow colour produced is measured at 256, 294, 262, 243 and 246 nm, respectively. Chloramphenicol is determined similarly to the tetracyclines after hydrolysis with 40% sodium hydroxide solution and the colour is measured at 240 nm. The proposed method has been successfully applied to the determination of these drugs in various pharmaceutical preparations.

Spectrophotometric determination of tetracyclines and cephalosporins with ammonium vanadate.

A spectrophotometric method for the determination of some tetracyclines as well as some cephalosporins is described. The drug is boiled with ammonium vanadate solution in sulphuric acid medium for 10 min and the absorbance of the colour developed is measured at 750 nm. The proposed method can be successfully applied to the determination of tetracycline hydrochloride, oxytetracycline hydrochloride, doxycycline hyclate, demeclocycline hydrochloride, chlortetracycline hydrochloride, cephalothin sodium, cephaloridine and cephapirin sodium. These drugs can be determined either in pure form or in pharmaceutical preparations.