High-performance liquid chromatographic separation of Porphyromonas gingivalis fimbriae

A right lung cancer case is presented, aged 65 years, obese, submitted to a right lung resection. Stress is laid on the difficult evolution concerning the haemodynamics and particularly the breathing owing to the association of risk factors.     

High-performance liquid chromatographic separation and electrochemical detection of cephalosporins

It was found that both normal human myometrium and uterine leiomyoma contain several glycosaminoglycans. In contrast to many normal and tumour tissues the amount of hyaluronic acid is very low and the proportional amount of sulphated glycosaminoglycans is distinctly higher. It is of interest that heparan sulphate is the major glycosaminoglycan component both in normal myometrium, and in leiomyoma. The amount of hyaluronic acid in myometrium and in the leiomyoma is very low. No significant change in hyaluronate content was observed during the tumour growth. In contrast to that the amount of some sulphated glycosaminoglycans (heparan sulphate, keratan sulphate, chondroitin sulphates and heparin) distinctly increased. It is suggested that some of the GAGs participate in the creation of a storage depot for biologically active molecules (growth factors, enzymes) which are thereby stabilized and protected. Hydrolytic degradation of some GAGs may result in the release of some cytokines which may promote the tumour growth and stimulate collagen biosynthesis by tumour cells.     

High-performance liquid chromatographic determination of tramadol in human plasma

Tramadol has been determined in human plasma samples using a sensitive high-performance liquid chromatographic method. The plasma samples were extracted with tert.-butylmethyl ether in one-step liquid-liquid extraction (recovery 86%) and analyses of the extracts were performed on reversed-phase silica gel using ion-pair chromatography (verapamil as an internal standard) and fluorescence detection. The method was applied to the determination of tramadol levels in twelve healthy volunteers after oral administration of 100 mg of tramadol in capsules of Protradon and Tramal.     

High-performance liquid chromatographic determination of midazolam in rat brain

The authors tested whether perfectionism dimensions interact with specific stress to predict depression over time. A sample of 103 current and former patients completed measures of perfectionism and depression at Time 1 and measures of stress and depression 4 months later. After controlling Time 1 depression, self-oriented perfectionism interacted only with achievement stress to predict Time 2 depression. Socially prescribed perfectionism did not interact with achievement or social stress to predict Time 2 depression, but it did predict Time 2 depression as a main effect. The results provide support for the contention that perfectionism dimensions are involved in vulnerability to depression over time.     

High-performance liquid chromatographic method for the determination of fenofibric acid and reduced fenofibric acid in human blood, plasma and urine

In this study, a very reliable HPLC method was developed for the determination of fenofibric acid and reduced fenofibric acid in the biological samples described as follows. After addition of the internal standard solution and 0.5 M HCl to the biological sample, fenofibric acid, reduced fenofibric acid and the internal standard were extracted with a mixed solvent of n-hexane and ethyl acetate (90:10) from the mixture. The acids were back-extracted from the organic phase with 0.1 M Na2HPO4 and then re-extracted from the aqueous phase with a mixed solution of n-hexane and ethyl acetate (95:5) after addition of 0.5 M HCl. The organic phase was evaporated to dryness under the vacuum. The residue was dissolved in MeOH and diluted with distilled water. An aliquot of the resulting solution was injected on the HPLC. High reproducibility was observed in this HPLC method (C.V.% less than 4%). Moreover it was confirmed that the conjugates in the urine could be hydrolyzed by incubation at 37 degrees C for 18 h after addition of 400 IU of beta-glucuronidase.     

High-performance liquid chromatographic methods for determination of marine biotoxins

Paralysing and diarrhetic shellfish poisonings (PSP and DSP) are important intoxications caused by the consumption of shellfish, mainly bivalve molluscs, contaminated by certain species of toxic dinoflagellates present in the marine phytoplankton. Their appearance and massive reproduction take place in some periods of the year, causing the phenomenon commonly known as 'red tide'. This causes significant problems to health and to the economy of the Galician region. The AOAC mouse bioassay is the most commonly used method of analysis for these toxic compounds, being the official method in most countries. Owing to the lack of sensitivity and selectivity of the biological assay, HPLC methods were developed as an alternative methodology. In this paper work carried out on the improvement of the chromatographic conditions in order to achieve accurate information about the PSP and DSP compounds present in the studied samples is reported.     

High-performance liquid chromatographic determination of 4-methylpyrazole in plasma and in dialysate

A rapid method for the determination of 4-methylpyrazole (4-MP) levels in plasma and in dialysate by isocratic reversed-phase high-performance liquid chromatography with UV detection is described. The internal standard was the 3-methylpyrazole (3-MP). Plasma sample preparation consisted of a protein precipitation. Dialysate samples were injected without preparation. The method was linear up to 30 mg l(-1) in plasma and up to 5 mg l(-1) in dialysate. The within-day precisions (C.V.) were less than 4% in plasma and were less than 2% in dialysate. The day-to-day precisions (C.V.) were less than 7% in plasma and were less than 3% in dialysate. This method is easy to perform and has practical interest for clinicians who need to monitor in emergency 4-MP levels in ethylene glycol and methanol poisonings.     

High-performance liquid chromatographic separation of microcystins derivatized with a highly fluorescent dienophile

Microcystins are potent hepatotoxins produced by cyanobacteria, and are also tumor promoters as well as potent inhibitors of the catalytic subunits of protein phosphatases 1 and 2A. In order to establish a physicochemical method for individual detection and determination of trace amounts of microcystins, we developed a derivatization method for fluorescence (FL) and chemiluminescence (CL) detection, in which a highly fluorescent dienophile, DMEQ-TAD (4-[2-(6,7-dimethoxy-4-methyl-3-oxo-3,4-dihydroquinoxalinyl) ethyl]-1,2,4-triazoline-3,5-dione), was used as the labeling reagent. DMEQ-TAD reacted smoothly with the conjugated diene of the Adda moiety to give 2 stereoisomers of the adducts. As a result of the extensive experiments, the following reaction conditions were optimized for the labeling: sample amount, 10 micrograms; reaction solvent, DMF:acetonitrile (1:1); reaction time, 15 minutes; reaction temperature, 70 degrees C; amount of DMEQ-TAD used relative to that of microcystin, 80 equivalent. The resulting 6 adducts from microcystins-LR, -YR, and -RR can be separated from one another using the following reversed phase HPLC conditions in combination with a clean-up using ODS silica gel: column, Cosmosil 5C18-AR (150 x 4.6 I.D. mm); mobile phase, methanol:0.05M phosphate buffer (pH 3) (1:1); flow rate, 1.0 ml/min; detection, FL lambda ex 370 nm, lambda em 440 nm. The detection limits of the DMEQ-TAD derivatives were estimated to be 100 and 500 pg for LR, and 65 and 2,500 pg for RR using FL and CL detections, respectively; and the detection behavior was different from that of the Dns-Cys derivatives, which were more sensitive to CL than FL.     

High-performance liquid chromatographic determination of bisacodyl in pharmaceutical dosage forms marketed in Australia

HPLC methods have been developed for the assay of bisacodyl in various pharmaceutical forms. The extraction procedures are simple and the HPLC conditions separate bisacodyl from its degradation products. The chromatography was performed using a Merck LiChrospher RP-select B column, a mobile phase of 55% acetonitrile/45% 0.05 M KH2PO4 and detection by UV at 214 nm.     

High-performance liquid chromatographic determination of L-aspartyl-L-phenylalanine methyl ester in various food products and formulations

A simple, rapid, and specific high-performance liquid chromatographic (HPLC) procedure is described for the analysis of the chemical sweetener L-aspartyl-L-phenylalanine methyl ester (aspartame). Using a strong cation exchange column and pressures less than 1000 psig, an analysis can be performed in less than 15 min. The technique has been applied to a wide range of food products and formulations. No interferences were found in the samples studied. Recoveries are quantitative, and the coefficients of variation for replicate analyses are less than or equal to 2.5%.     

High-performance liquid chromatographic determination of diclofenac in human plasma using automated column switching

A validated high-performance liquid chromatographic procedure employing ultraviolet detection for the analysis of diclofenac in human plasma is reported. The method is rapid and, coupled with column switching, leads to a sensitive, accurate and reproducible assay. The retention times of diclofenac and the internal standard (4'-methoxydiclofenac, CGP-4287) are 6.4 and 7.6 min, respectively. The peak height versus plasma concentration is linear over the range 5.0-2000 ng/ml with a detection limit below 2.5 ng/ml. The mean absolute recovery of diclofenac using the described assay is 96.5% (n = 24). The inter- and intra-day accuracy and precision are within 8.3% of the actual values for all concentrations investigated. Furthermore, this procedure is applied to assess the pharmacokinetics of a single 75-mg oral dose of diclofenac sodium.     

High-performance liquid chromatographic determination of benzalkonium and naphazoline or tetrahydrozoline in nasal and ophthalmic solutions

A high-performance liquid chromatographic method is described for the determination of benzalkonium chloride homologues and naphazoline nitrate or tetrahydrozoline hydrochloride in ophthalmic and nasal solutions. The technique involves a one-step dilution (1:5) for sample preparation and direct injection onto a 5 mm RP C-8 column. The mobile phase is acetonitrile-diluted acetic acid (80:20, v/v) with 6 mM tetramethylammonium bromide. Detection is carried out at 260 nm with a diode array. The method is rapid, specific, reproducible and is especially useful for quality control procedures.     

High-performance liquid chromatographic determination of furosemide in plasma and urine and its use in bioavailability studies

Steroid hydroxylase cytochrome P450c17 has been previously purified from microsomal fractions of immature rat livers. In this study, we investigated the expression of P450c17 in rat livers to understand a role of steroidogenesis in the extrasteroidogenic tissue. Upon immunoblot analysis utilizing liver microsomes from rats, P450c17 was detected in 1 and 3 week old rats but not in adult rats. Data from immunohistochemical studies also showed a similar age-dependent expression of P450c17 and indicated that P450c17 detected in immature rat livers is localized in cells surrounding interlobular veins. This age-dependent expression of P450c17 in rat livers was observed in both sexes. Upon enzymatic analysis utilizing microsomal fractions from livers, levels of 17alpha-hydroxylase and 17,20-lyase activity for pregnenolone and progesterone increased by 3 weeks and dramatically reduced at 7 weeks, which is consistent with the expression level of P450c17. These data clearly indicate that P450c17 is expressed in immature rat liver to produce 17alpha-hydroxysteroids and C19-steroids. Based upon immunoblot analysis, the expression level of P450c17 in immature rat livers was approximately one third of that in testis. Compared expression level of P450c17 and total volume of organs between liver and testis, the total amount of steroid metabolites produced by liver P450c17 could be greater than that produced by gonadal P450c17. Because of the absence of P450c17 in rat adrenal glands, rat liver could be the major site for producing 17alpha-hydroxysteroids and C19-steroids in this particular period of life. Although physiological products formed by P450c17 in liver and their roles remain to be elucidated, this study suggests a large capacity of prepubertal rat liver for participating the production of steroid hormones and a putative importance of 17alpha-hydroxysteroids and C19-steroids, such as cortisol and androstendione, which are generally believed to be minor components of steroid hormones in rodents.     

High-performance liquid chromatographic determination of sulfated peptides in human hemofiltrate using a radioactivity monitor

Specific labeling of tyrosine sulfate-containing peptides was achieved using a differential iodination approach. In a complex peptide mixture from human hemofiltrate, cold iodination to saturate free iodine binding sites was followed by mild acidic desulfation of tyrosine sulfate and subsequent radioiodination using iodine-125. Reaction steps were controlled by amino acid analysis using o-phthaldialdehyde precolumn derivatization and by spiking with a sulfated cholecystokinin fragment (CCK4-S). Separation of the peptide mixture with RP-HPLC on a C18 column coupled to a radioactivity monitor led to the sensitive (< or = 5 pM) and specific determination of tyrosine sulfate-containing peptides.     

High-performance liquid chromatographic determination of a new oral thrombin inhibitor in the blood of rats and dogs

Donovanosis is a genital ulcer disease that occasionally has extragenital manifestations. This report describes a case of disseminated donovanosis in a 54-year-old woman from northern Australia who had subsequent thoracic vertebral osteomyelitis and spinal cord compression. Malignancy and vertebral tuberculosis were the major differential diagnoses. The patient had no genital lesions at the time of diagnosis of extragenital donovanosis but had undergone a hysterectomy, thus raising the possibility of prior disease of the uterine cervix (most previous cases have been associated with primary cervical disease). Despite treatment with doxycycline, she had no significant neurological improvement. Donovanosis disseminated to bone has been reported in 18 cases in the last 55 years. Awareness of donovanosis in the differential diagnosis of osteomyelitis and prompt pelvic examinations enabling early diagnosis of occult cervical disease are the most important measures in preventing morbidity and mortality due to disseminated donovanosis.     

High-performance liquid chromatographic analysis of aminoglycoside antibiotics

The Category Test (CT) and the Wisconsin Card Sort Test (WCST) have long been the major instruments used for the assessment of "frontal lobe" brain damage. These tests have often been used interchangeably by clinicians. However, research to date has disagreed on the extent to which these tests can be interpreted in a similar manner. The current paper examined the interrelationships between the tests in 112 mixed brain injured clients. The results showed relatively small correlations between the tests in the range of .4 to .6 which were eliminated when age, education, premorbid IQ (Vocabulary) and spatial skills (Block Design) were used as covariates. Regression analyses showed clear differences in which WAIS-R tests predicted each test, while factor analysis revealed little overlap between the tests except for a small relationship between the number of WCST categories completed and CT errors. The CT appeared to reflect spatial and spatial analysis skills while the WCST reflected verbal analysis and sequential skills. The results clearly indicate that the tests are not interchangeable and do not reflect the same underlying cognitive skills nor can they be interpreted in the same manner for neuropsychological purposes.     

High-performance liquid chromatographic determination of phenylephrine in human serum using column switching with fluorescence detection

A method for the determination of total phenylephrine (free plus conjugated) in human serum was developed using column-switching high-performance liquid chromatography (HPLC) with fluorescence detection. After serum was deproteinized with acetonitrile, the conjugated phenylephrine was hydrolyzed with diluted hydrochloric acid. The solution was evaporated to dryness. The reconstituted residue was analyzed with HPLC using a heart-cut technique. Good recoveries of the analytes from spiked human serum samples were obtained with small coefficients of variation. A good linear response was obtained for the concentration range 5-500 ng/ml. The lower limit of quantitation for phenylephrine in human serum was 5 ng/ml. The method was applied to the determination of phenylephrine in human serum after oral administration of phenylephrine hydrochloride.