bluuebunny/crossref_metadata_2025 huggingface dataset:
Fat graft myringoplasty: a cost-effective but underused procedure
Authors: Ozgursoy O B , Yorulmaz I
Published: May 2005

Objectives: The objective of this study was to evaluate the success of fat graft myringoplasty and to discuss the utilities and advantages of a fat graft in primary versus revision myringoplasties.

Methods: Eighteen patients who had not had previous otological surgery, and twelve patients whose tympanic membrane perforations have persisted despite myringoplasty with temporalis fascia were included in this prospective clinical trial. All patients were treated by fat graft myringoplasty and followed up for one year.

Results: Successful closure of the perforation was obtained in 82.4 per cent of the ears at the final follow up. The success rate in the group of patients who had not had previous otological surgery was higher than those of revision cases.

Conclusions: Adipose tissue provides the basic requirements for grafting of the tympanic membrane, with its own favourable characteristics. Fat graft myringoplasty is a cost-effective alternative in small perforations of the tympanic membrane, including revision cases.
A simple method for preparing an ear wick
Authors: Badran K , Karkos P D
Published: May 2005

We present a simple method for preparing an ear wick for treating otitis externa in ENT outpatient clinics. In our experience, this method is efficient, economical and clean, and ensures an equal distribution of the medication along the wick.
Immunoreactivity of the Septins SEPT4, SEPT5, and SEPT8 in the Human Eye
Authors: Pache Mona , Zieger Barbara , Bläser Susanne , Meyer Peter
Published: May 2005

We aimed to examine the distribution of SEPT4, SEPT5, and SEPT8 in the human eye. For each septin, five to six normal human eyes were examined by immunohistochemical staining of paraffin sections using polyclonal antibodies against SEPT4, SEPT5, and SEPT8 and an avidin biotin complex immunodetection system. SEPT4 immunoreactivity (IR) was detected primarily in the epithelium of cornea, lens, and nonpigmented ciliary epithelium; in the endothelium of cornea and vessels of iris and retina; and in the retinal nerve fiber layer, the outer plexiform layer, the outer segments of the photoreceptor cells, the inner limiting membrane of the optic nerve head, and optic nerve axons. SEPT5-IR was present in corneal endothelial cells, iris tissue, nonpigmented ciliary epithelium, and epithelial cells of the lens. SEPT8-IR almost paralleled that of SEPT4, except for a lower SEPT8-IR of the outer photoreceptor segments and a positive staining of the meningothelial cell nests in the subarachnoidal space of the bulbar segment of the orbital optic nerve. In conclusion, SEPT4, SEPT5, and SEPT8 are expressed in various ocular tissues, each revealing a distinct expression pattern. Both physiological and potential pathophysiological role of septins in the human eye deserve further investigation.
Kompositionsfasern aus Polyethylen und Polyethylenterephthalat
Authors: Dimov K. , Stojanov St. , Georgiev J.
Published: May 2005

Es wurde ein positiver Einfluß des Zusatzes von ε‐Caprolactam auf die Dispergierung der Komponenten und das Faserbildungsvermögen aus der Dispersionsschmelze festgestellt. Die Wechselwirkung in der Dispersionsschmelze bei beiden Komponenten wurde untersucht. Es wurde gefunden, daß der auf den Thermogrammen beobachtete exotherme Peak im Bereich von 200 bis 210°C einem Abbauprozeß des Polyethylens und der chemischen Wechselwirkung zwischen Polyethylen und Polyethylenterephthalat zuzuschreiben ist. Die technologischen Parameter zur Herstellung von PE‐PETP‐Kompositionsfasern unter Laborbedingungen wurden ermittelt. Die erhaltenen Fasern können mechanisch fibrilliert werden.
Permanent‐antielektrostatische Modifizierung von Polyacrylnitril‐Faserstoffen mit Blockcopolyetherester. 2. Mitt.: Antielektrostatische Eigenschaften modifizierter Fäden
Authors: Albrecht W. , Gröbe V. , Klug P. , Makschin W. , Mann G.
Published: May 2005

Blockcopolyetherester werden Polyacrylnitril‐Spinnlösungen zugesetzt und die erhaltenen Fäden hinsichtlich ihres Leitfähigkeitsverhaltens charakterisiert. Wie die Ergebnisse zeigen, stellen Blockcopolyetherester für naßersponnene PAN‐Fasern geeignete antielektrostatische Modifikatoren dar. Dabei besitzen die Koagulationsbedingungen einen signifikanten Einfluß auf die Permanenz des Modifiziereffektes. Die Ursache wird aufgezeigt.
Polymere Derivate des Hydrazins mit NN und NN‐Bindungen in der Seitenkette. Fortschrittsbericht
Authors: Derbišer V. E.
Published: May 2005

Die Synthesemöglichkeiten, Physikalisch‐chemischen Eigenschaften und Anwendungsbereiche von monomeren und polymeren Hydrazinverbindungen mit NN und NN‐Bindungen in den Seitenketten werden betrachtet. Beispiele von analogen Umsetzungen, Kettenreaktionen und der Ionenaustauscheraktivität der Polymere werden aufgeführt. Die Perspektiven der Anwendung der polymeren Produkte in der Chemie und chemischen Technologie, Medizin, Textil‐, Papier‐ und Lederindustrie sowie anderen Industriezweigen werden aufgezeigt.
Melting and morphology of high molecular weight poly(ethylene oxide) foils moulded at different temperatures
Authors: Bogdanov B. , Mihailov M.
Published: May 2005

Using differential scanning calorimetry and light microscopy the structure of foils of two types of high molecular weight poly(ethylene oxide) has been studied in dependence of moulding temperature. Non‐linear relationships between melting temperatures, enthalpy of fusion and moulding temperature were established. It is shown that the moulding temperature range of PEO foils with maximum tensile strength coincides with PEO melting temperature range.
Columnar mesophases of alkylated hexa‐peri‐hexabenzocoronenes with remarkably large phase widths
Authors: Herwig Peter , Kayser Christoph W. , Müllen Klaus , Spiess Hans Wolfgang
Published: May 2005

Polyaromatic hydrocarbons are model compounds for graphite and have interesting electronic and optoelectronic properties. The synthesis and preliminary characterization of hexaalkyl‐substituted hexa‐peri‐hexabenzocoronenes (see figure) are described. It is shown that they exhibit hexagonal columnar mesophases with remarkably large widths, e.g., 339K for R = nC12H25.

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Designing of extrusion lines
Authors: Wortberg J. , Haberstroh E. , Lutterbeck J. , Masberg U. , Schmidt J. , Targiel G.
Published: May 2005

The design of extrusion lines deals with the extruder and the die as well as with the down stream equipment, especially the cooling section. This paper aids in the design of these three units, regarding different aspects. The scale‐up of extruders by means of the model theory is demonstrated in its practical use with examples. Emphasis is laid on the design of series of single screw extruders with mixing‐pins and of twin‐screw extruders (scale‐up). There the adequate selection of the necessary restrictions for the compilation of model laws is discussed in detail. This is an approach to the safe machine design on the basis of model theory.

The present standard of the calculation of threedimensional flow patterns in extrusion dies by means of the finite‐element‐method (FEM) is shown in order to point out how design‐aids for the die‐designer are derived from these calculations. After a discussion of application‐criteria for the FEM, examples will show possible ways of using FEM‐results.

For the shaping of Y‐branches in twin‐screw machines the FEM‐results point to possible plate‐out areas and to their avoidance by geometrical modifications. The calculation of a die for a T‐profile helps to design the passages between entry and exit sections. Finally, flow coefficients for the calculation of pressure losses in different cross sections are given.

The design and optimization of cooling sections, as it can be done with the aid of the actual cooling models, is shown for some important extrusion processes. Heat transfer coefficients for practical cases (film‐sheet‐, pipe‐ and parison extrusion) are presented. Examples show, how diagrams for the design and optimization of cooling sections (for example the reduction of internal stresses and warping) can be made, using a microcomputer.
Experimental study of reactive chaotic flows in tubular reactors
Authors: Boesinger C. , Le Guer Y. , Mory M.
Published: May 2005

For many reactive processes, fluid mixing has a significant effect on the rate of a chemical reaction and on the quality of the product. Mixing in a chaotic flow reactor is a promising phenomenon to control and optimize chemical processes. The effect of three‐dimensional (3‐D) chaotic flow advection on mixing efficiency and on chemical reaction advancement is examined. An experimental comparison is made, for low Reynolds number flows, between two tubular reactors made of successive bends, with the same number of bends (equal to 80) mounted in different configurations : a helical configuration (for regular flow) and a chaotic flow configuration with bends in perpendicular planes. We show that the mixing and the chemical reaction (for an instantaneous bimolecular chemical reaction) are more efficient in the chaotic flow reactor than in the helical reactor. The different effects of chaotic advection, molecular diffusion and reaction are discussed in view of laboratory findings. © 2005 American Institute of Chemical Engineers AIChE J, 2005
Product engineering for man‐portable power generation based on fuel cells
Authors: Mitsos Alexander , Hencke Michael M. , Barton Paul I.
Published: May 2005

Microfabricated fuel cell systems are a promising alternative to batteries for man‐portable power generation. These devices are potential consumer products that constitute a more or less complex chemical process, and can therefore be considered chemical products. A great variety of potential devices are being considered in various research institutions and thus there is a need for a systematic product design methodology, including comparison of alternatives and examination of the influence of technological parameters. The design of these product/process hybrids is inherently different from macroscale process design because of the differing design specifications, objectives, and constraints, as well as the relative importance of the underlying physico‐chemical phenomena. Heat losses substantially influence the process performance, so the processes are highly spatially integrated. Consequently, flowsheet design and layout need to be considered simultaneously. In this paper we present our methodology and perform a number of case studies, including studies of scaling of the processes and effects of layout options and relevant technological parameters. © 2005 American Institute of Chemical Engineers AIChE J, 2005
The effect of central nervous system stimulants on tourette syndrome
Authors: Golden Gerald S.
Published: May 2005

A survey of patients with Tourette syndrome uncovered 32 who had been exposed to central nervous system stimulants. In 17 (53%) of these patients, symptoms were markedly accentuated by the drugs. Two patients whose Tourette syndrome developed suddenly when methylphenidate was administered are also reported.
Alcoholic neuropathy: Clinical, electrophysiological, and biopsy findings
Authors: Behse F. , Buchthal F.
Published: May 2005

Nerve conduction and biopsy findings from the sural nerve in 37 patients with alcohokic neuropathy were compared with findings in 6 patients who had neuropathy associated with postgastrectomy malnutrition. Half the patients with alcoholic neuropathy had both muscle weakness and sensory loss, half had only sensory impairment, but all had electromyographic signs of denervation. Only half the patients, with or without muscle weakness, had signs of malnutrition.

In alcoholics, sural nerve conduction velocity was slowed to at most 60% of normal, correlating with loss of large fibers. These findings, together with a marked reduction in amplitude of the sensory potentials, are consistent with axonal loss. Myelinated fiber counts showed loss of small and large fibers in most nerves, retaining a bimodal distribution. Signs of regeneration were rare. Segmental demyelination was found in only 0.3% of teased fibers. Electron microscopy confirmed axonal degeneration of myelinated and unmyelinated fibers.

Neuropathy after gastrectomy malnutrition was clinically similar to alcoholic neuropathy. Conduction velocities were slower than expected from the diameter of the largest myelinated fibers, however, and teased fibers showed segmental demyelination. The findings are against alcoholic neuropathy being due to malnutrition and suggest a toxic action on peripheral nerve.
Ultraweak photon emission in germinating seeds: A signal of biological order
Authors: Bajpai R. P. , Bajpai P. K. , Roy D.
Published: May 2005

Photon emission from germinating gram seeds at various stages of growth exhibits a definite pattern. The pattern of emission changes when a seed is disrupted by physical processes, e. g. mechanical crushing, cooling or heating. The disrupted seeds do not grow. The change in the biological order responsible for seed growth and the observed changes in the pattern of photo emission suggest a link between the macroscopic spatio‐temporal organization and metabolic processes.
Measurement of urinary cystine and cysteinyl‐penicillamine in patients with cystinuria
Authors: Sampson D. C. , Stewart P. M. , Hammond J. W.
Published: May 2005

A high‐performance liquid chromatographic method with electrochemical detection (LC/EC) was developed to measure cystine and cysteinyl‐penicillamine disulfide in the urine of patients screened or treated for cystinuria. Urine was acidified, centrifuged to remove urinary protein, diluted and injected. The disulfides were separated on a reversed‐phase column, reduced at the upstream electrode of a dual electrochemical detector with gold–mercury amalgam (Au/Hg) electrodes and the resultant thiols measured at the downstream electrode. The sample preparation is simple, the analysis rapid, specimens can be easily batched and the specificity of the method is better than those of two other separative procedures with which it was compared. The coefficient of variation for cystine in cystinuric urine is 6.7%, 5.5% and 3.2% for levels of 0.09, 0.52 and 1.02 mmol/l respectively, and for cysteinyl‐penicillamine disulfide 2.6% and 7.5% for levels of 0.45 and 0.98 mmol/l respectively. Urine for analysis of these disulfides should not be collected within 24 hours of administration of the radiopaque agent diatrizoate but no other interference to the assay has been noted. This method is suitable as a screen for cystinuria in patients with renal tract calculi, for ongoing monitoring of cystinuric patients and to check patient compliance with d‐penicillamine therapy.
Column separation using Bio‐Gel P100 for the characterization of the products of human lung elastin degradation by leucocyte elastase and cathepsin G
Authors: Smyrlaki Marie , Davril Monique , Hayem Annette
Published: May 2005

The solubilization of human lung elastin by leucocyte elastase and cathepsin G is described. Elastolysis kinetic studies clearly show that leucocyte elastase is more efficient in solubilizing elastin fibres than is cathepsin G. Cathepsin G can degrade elastin but at a much slower rate.

Characterization of elastase and cathepsin G soluble elastin fragments, obtained after 24 h of digestion (enzyme‐substrate ratio, 1:100), was first performed by isoelectric focusing. Whole digests were focused as 6 bands in a pH range 4.2 to 4.7 and were found to have no significant differences in amino acid compositions.

Biogel P‐100 gel filtration of the elastase digested fragments separated a major excluded fraction (Mr's: 80 000 to 30 000) and a small retained one (Mr's: 6000 to 4000). Conversely, cathepsin G digests were eluted as a minor excluded fraction and a more important retarded one (Mr's: 6000 to 4000). Only the high molecular weight fractions of both enzymes digests contain crosslinked amino acids; this assigns a role for desmosines in the resistance of elastin to these proteases. These results are discussed in comparison with the data obtained by others.
An automated direct‐injection HPLC‐method for the electrochemical/fluorimetric quantitation of monoamines and related compounds optimized for the screening of large numbers of animals
Authors: Seyfried C. A. , Adam G. , Greve T.
Published: May 2005

An automated, highly stable HPLC system is described allowing the quantitation of monoamines and related compounds with virtually online data processing and statistical evaluation of the mean values of various differently treated groups of animals. The system is highly suited to the screening of drugs involving large numbers of samples. To ensure long‐term, uninterrupted performance, two robust chromatographic systems were developed optimized to separate neighboring peaks as widely as possible. This was achieved by using mobile phases of relatively low pH to retard acidic compounds, and optimal concentrations of the ion‐pairing reagent to manipulate the retention times of amines on the RP‐18 column, resulting also in clearcut separations from the solvent/tissue peak. Direct injection of deproteinized tissue samples, requiring no clean up procedures is used. One faster system allows measurement of the main biogenic amines, metabolites and TRP, whereas another system allows the simultaneous quantitation of DOPA, 5HTP, NA, MOPEG, NMN, A, MN, VMA, DA, 3MT, OOP AC, HVA, 5HT, 5HIAA and TYR. By pretreatment of animals with a decarboxylase inhibitor the latter system offers the possibility of detecting drug effects in the same animal on either dopamine and serotonin turnover or noradrenaline and serotonin turnover, depending on the brain area chosen. The system described has been running for over a year without major disturbance and with minimal technician attendance.
Direct determination of vanillylmandelic acid in human urine by reversed‐phase HPLC
Authors: Shang Zhen‐Hua , Fang Shu‐Hua , Wang Jun‐De , Zhou Liang‐Mo , Ju Chang‐De
Published: May 2005

A reversed‐phase HPLC method for the determination of epinephrine, norepinephrine, dopamine, and vanillylmandelic acid (VMA) has been developed. The concentration of VMA in the urine of hypertensive patients was measured by direct injection after centrifugation. The method is useful for the diagnosis of pheochromocytoma.
Determination of artemether in plasma and whole blood using HPLC with flow‐through polarographic detection
Authors: Huang Yuexian , Xie Guanghua , Zhou Zhongming , Sun Xiaomiao , Wang Yanli
Published: May 2005

An HPLC method with polarographic detection for the trace determination of artemether in plasma and whole blood was developed and applied to pharmacokinetic and clinical pharmacological studies. The method showed high sensitivity and selectivity because of the easy reduction of the peroxide linkage of artemether at the mercury drop electrode. The detection limit was 10 ng and the detector response was linear over the range of 10 ng to 1 μg artemether injected onto the column. The largest relative standard deviation of 10 replicate measurements of standard solutions (concentrations of 10 ng/mL–1 μg/mL) was 8%. The recovery from whole blood and plasma of added drug (concentrations of 15–48 ng/mL) was 71–100%.
Routine clinical determination of carotene, vitamin E, vitamin A, 25‐hydroxy vitamin D3 and trans‐vitamin K1 in human serum by straight phase HPLC
Authors: Van Haard Paul M. M. , Engel Roel , Postma Tjeerd
Published: May 2005

A universal extraction procedure is described for fat‐soluble vitamins in human serum. Methods are presented for routine quantitative analysis by isocratic straight phase HPLC with UV‐detection of (α + β)‐carotene, vitamin E. (α‐tocopherol) and vitamin A (all‐trans‐retinol) in one single run, and of vitamin K1 (trans‐phylloquinone) and 25‐hydroxy vitamin D3 after sample clean‐up using disposable reversed‐phase cartridges. The limits of detection, precisions and selectivities of the developed assays are shown to be satisfactory after more than three years' experience. The routine clinical determination of fat‐soluble vitamins can be performed in less than 5 mL of serum. Analyses of external quality control and randomly taken outpatient samples are shown to be of great value in assessing laboratory performance.
Simple and rapid GLC method for the determination of orphenadrine in human plasma
Authors: Contin Manuela , Riva Roberto , Albani Fiorenzo , Baruzzi Agostino
Published: May 2005

A rapid and specific method has been developed for the determination of orphenadrine concentration in plasma. It involves a one‐step sample preparation using n‐hexane/isopropyl alcohol (98:2) extraction, and analysis by gas chromatography on a wide bore capillary column using nitrogen/phosphorus detection. This procedure considerably simplifies previously reported assays and is specific and sensitive enough for the determination of orphenadrine in plasma of patients on chronic therapy.
HPLC determination of cis‐diamminedichloroplatinum(II) in plasma and urine with UV detection and column‐switching
Authors: Kizu Ryoichi , Hayakawa Kazuichi , Miyazaki Motoichi
Published: May 2005

A method for determining cis‐diamminedichloroplatinum(II) (CDDP), an anticancer drug, in plasma and urine by HPLC with UV detection and column‐switching has been developed. Typical conditions were as follows. An apparatus was composed of two columns, two pumps, a UV detector, a sample injector with a 100 μL loop, a switching valve, a column oven and a recorder. A Rheodyne model 7125 sample injector was used as the switching valve. A precolumn (4.6 mm ID × 25 cm) was packed with MCI GEL CK10S (a strong cation exchanger), and an analytical column (4.6 mm ID × 5 cm) was packed with MCI GEL CDR10 (a strong anion exchanger). Both columns were connected in series via the switching valve. The CDDP‐containing fraction of the effluent from the precolumn was loaded to the analytical column by column‐switching and the effluent from the analytical column was monitored at 210 nm. An eluent of 0.3 M sodium dihydrogen phosphate was pumped at a flow rate of 1 mL/min and the columns were maintained at 40°C. CDDP was eluted at about 11 min and the identity of the peak of CDDP on the chromatogram was confirmed by its 3‐dimensional chromatogram and analysis of platinum in the column effluent. Under the conditions described above, a linear relationship was obtained between peak height and concentration of CDDP up to 100 μM. Correlation efficients were 0.998 for plasma and 0.999 for urine. The detection limit was 0.1 μM for CDDP in both plasma and urine (S/N = 3, 0.005 AUFS). The reproducibility was within 3% for 10 determinations. The CDDP concentrations in plasma and urine of a patient with ovarian carcinoma receiving CDDP treatment could be determined.
A simple method for the characterization of photoproducts from DNA applied to the cis‐syn thymine dimer
Authors: Salter L. F. , Thomas R. C.
Published: May 2005

A method for the unambiguous characterization of DNA photoproducts has been developed. It does not require radio‐labelled DNA, or specialized techniques. In the preliminary step, UV‐irradiated DNA is hydrolysed to its constituent bases and photoproducts. The photoproducts are then separated from nucleic acid bases using low pressure ion‐exchange chromatography on a Dowex 1 × 8 200–400, and an Amberlite CG–50–H+ column. Further separation and purification of photoproducts is carried out on the HPLC Whatman Partisil ODS2 column, using 15% MeOH. The procedure is simple, reproducible and versatile.
A rapid and specific HPLC‐electrochemical method for the determination of endogenous 5‐methyltetrahydrofolic acid in plasma using solid phase sample preparation with internal standardization
Authors: Lucock M. D. , Hartley R. , Smithells R. W.
Published: May 2005

A rapid and specific HPLC‐electrochemical method for determining endogenous 5‐methyltetrahydrofolic acid (5MeTHF) in plasma is described. Quantitative solid phase extraction of 5MeTHF and internal standard, β‐hydroxyethyltheophylline, was carried out using proprietary phenyl bonded‐silica columns (Bond Elut Phenyl cartridges, 1.0 mL capacity). Chromatographic separation was achieved using a mobile phase consisting of 15% (v/v) methanol in 0.05 M KH2PO4, pH 3.5 at a flow rate of 2.0 mL/min in conjunction with a Waters Assoc. radially compressed Nova‐Pak phenyl column (10 cm × 8 mm, 4 μm bonded silica). The internal standard was measured by UV detection at 254 nm. A Bioanalytical Systems Inc. LC‐17 glassy carbon oxidative flow cell with a potential held at +0.35 V vs Ag/AgCl using the LC‐4A amperometric controller allowed levels of 1–2 ng/mL 5MeTHF to be measured in 500 μL of plasma. Daily appraisal of the ratio produced by authentic materials clearly demonstrated that quantitation using dual detection was not subject to problems of differential response. Inter‐day variation of the differential detector response is cited. Comparison of the Lactobacillus casei bioassay with HPLC demonstrates good agreement between methods but at the same time highlights the drawback of using such non‐specific methods to measure samples where more than one folylmonoglutamate may be present. Antoxidant free storage for three months at −70± C in darkness resulted in no deterioration of 5MeTHF. A comparison of the means and range of values for plasma folate obtained using HPLC, L. casei bioassay and the radiometric binding assay is reported.
HPLC method for simultaneous determination of clobazam and N‐desmethylclobazam in human serum, rat serum and rat brain homogenates
Authors: Gaźik Wieslaw R. , Podleśany Jerzy , Filipek Marian
Published: May 2005

A method for simultaneous determination of clobazam (CBZ) and its active metabolite N‐desmethylclobazam (DCBZ) in various biological samples by RP‐HPLC with UV detection is described. The determination of both CBZ and DCBZ is performed without derivatization. The internal standard is diazepam. The method is rapid and simple with sensitivity limits of 10 ng/mL for both CBZ and DCBZ and is suitable for routine analysis as well as for animal studies.
Electronic interaction chromatography on porous graphitic carbon. Separation of [99mtc]pertechnetate and perrhenate anions
Authors: Lim C. K.
Published: May 2005

The oxo anions of technetium‐99m and rhenium, pertechnetate (TcO) and perrhenate (ReO), have been separated by high performance liquid chromatography on porous graphitic carbon with aqueous trifluoroacetic acid or salt solutions as eluent. Chromatographic retention was a result of electronic interaction between the lone pair electrons of the anions and the delocalised ±‐electron clouds of the porous graphitic carbon. Retention and resolution can be controlled by the concentration and/or species of eluents which can compete with the solutes for electronic interaction being used for elution.
Direct determination of unconjugated HVA in human plasma filtrates by HPLC coupled with dual‐electrode coulometric electrochemical detection
Authors: Gerhardt Greg A. , Drebing Carla J. , Stephen Christopher , Freedman Robert
Published: May 2005

We report a procedure for the rapid determination of unconjugated homovanillic acid (HVA) in human plasma by cartridge filtration followed by direct injection into an isocratic HPLC system coupled with dual‐electrode coulometric electrochemical detection. Sample preparation is rapid and more than 72 samples can be studied in 24 h using an automated HPLC system. The intra‐ and interassay precisions of the assay equal or exceed previously reported methods. While this methodology has been employed to study plasma free HVA, the concept of the technique may be applicable to other compounds, as well as different assay procedures, to greatly decrease sample preparation time.
Chromatography as a reference technique for the determination of clinically important steroids
Authors: Robards K. , Towers P.
Published: May 2005

Chromatographic methods (paper chromatography, thin layer chromatography, high performance liquid chromatography, gas chromatography and gas chromatography‐mass spectrometry) for the determination of clinically important steroids in biological specimens are reviewed. The emphasis is on the use of gas chromatography, gas chromatography‐mass spectrometry and high performance liquid chromatography as reference rather than routine techniques. Chromatographic methods are compared with colorimetric, fluorimetric and radioimmunoassay procedures in terms of simplicity of operation, cost and ability to analyse large numbers of specimens. The importance of correct specimen collection and storage are discussed. Sample preparation techniques for the various analytical methods are described. These include extraction of free and conjugated steroids from serum, plasma, urine and saliva by solvent partition, with polymer‐based resins such as Amberlite XAD‐2, DEAE‐Sephadex and Sephadex resins bonded with various other function groups and, more recently, with chemically bonded reversed‐phase silicas.
The determination of total and unbound midazolam in human plasma. A comparison of high performance liquid chromatography, gas chromatography and gas chromatography/mass spectrometry
Authors: de Vries J. X. , Rudi J. , Walter‐Sack I. , Conradi R.
Published: May 2005

Midazolam concentrations in patients' plasma was determined after extraction with high performance liquid chromatography (HPLC), gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). GC was selected for routine plasma assays in terms of selectivity, simplicity, precision, accuracy and sensitivity (0.02 μg/ml); HPLC analysis was less sensitive (0.1 μg/mL) than GC; GC/MS was used for analysis validation. Plasma protein binding of midazolam was determined by GC in patients' plasma after in vitro incubation with midazolam, ultrafiltration and extraction; 5% of the drug was unbound to plasma proteins. Midazolam distribution in lipoprotein fractions separated by ultracentrifugation of plasma obtained from patients on prolonged midazolam treatment was also assayed by GC.
Oxalate/hydrogen peroxide chemiluminescence reaction. A 19F NMR probe of the reaction mechanism
Authors: Chokshi Hitesh P. , Barbush Michael , Carlson Robert G. , Givens Richard S. , Kuwana Ted , Schowen Richard L.
Published: May 2005

The mechanism of the oxalate/hydrogen peroxide chemiluminescence reaction has been examined by magnetic resonance techniques. Investigation of the reactive intermediates involved in chemiluminescence was carried out with bis(2,6‐difluorophenyl)oxalate (DFPO) using 19F NMR to probe its reactions with aqueous hydrogen peroxide. Formation and reactions of the intermediate hydroperoxy oxalate ester B along with the formation of the half ester product C and difluorophenol D were monitored by 19F NMR. When the reaction of DFPO and aqueous hydrogen peroxide was carried out in the presence of dansylphenylalanine, a typical fluorescent analyte, the intensity of the resonance due to the intermediate B was diminished in direct proportion to the concentration of the analyte. Comparison of the time/intensity profile of the chemiluminescence emission with that of the 19F NMR transient suggests that the hydroperoxy oxalate ester B is the likely ‘reactive’ intermediate, capable of participating in a chemically initiated electron exchange luminescence mechanism.
High performance liquid chromatographic measurement of bisoprolol in plasma
Authors: Eastwood R. J. , Jerman J. C. , Bhamra R. K. , Holt D. W.
Published: May 2005

A simple high performance liquid chromatographic method has been devised for the measurement of bisoprolol in plasma or serum. The sample (200 μL) is vortex mixed for 30 s with 2 M Tris solution (50 μL), aqueous internal standard (benzimidazole, 2.0 mg/L, 50 μL) and methyl t‐butyl ether (200 μL). After centrifugation (9950 × g, 2 min), a portion of the resulting extract is analysed on a microparticulate (5 μm) silica column using 1 mM camphorsulphonic acid in methanol as the mobile phase. Detection is by fluorescence at an excitatioh wavelength of 215 nM. The lower limit of accurate measurement for the assay is 10 μ/L (CV% = 8.9, n = 9) with a lower limit of detection of 5 μg/L. There is minimal interference from either commonly prescribed drugs or endogenous compounds.
Separation of glycoprotein‐N‐glycans by high‐pH anion‐exchange chromatography
Authors: Pfeiffer Günter , Geyer Hildegard , Geyer Rudolf , Kalsner Inge , Wendorf Petra
Published: May 2005

A series of high‐mannose and complex type glycoprotein‐N‐glycans was subjected to high‐pH anion‐exchange chromatography. The results revealed that this method represents a useful tool for analytical characterization of single oligosaccharides as well as preparative separation of complex mixtures of carbohydrate side‐chains. On the other hand, it became evident that in several cases a combination of different chromatographic techniques is required for efficient separation of individual oligosaccharide species.
Microsomal Δ9, Δ6 and Δ5 desaturase activities and liver membrane fatty acid profiles in alcohol‐fed rats
Authors: Venkatesan S. , Rideout J. M. , Simpson K. J.
Published: May 2005

In experimentally produced alcoholic fatty liver microsomal fatty acid composition was measured using gas chromatography. The results showed an increase in linoleic acid (18:2, n‐6) and hexadecaenoic acid (22:6, n‐3) and a decrease in arachidonic acid (20:4, n‐6) in alcohol‐fed rats. Using high performance liquid chromatographic separation of radiolabelled substrate and products, Δ9, Δ6 and Δ5 desaturase enzymes were assayed. The activity of Δ9 and Δ5 desaturase was decreased in alcohol‐fed rats and Δ6 desaturase activity was similar in control and alcohol‐fed groups. These results indicated there was no causal relationship between desaturase activity and membrane fatty acid changes. Increased amounts of eicosatrienoic acid (20:3, n‐9) in rats fed <5% fat were observed in both control and alcohol‐fed rats. The results indicated that essential fatty acid deficiency was not due to alcohol consumption.
A new high performance liquid chromatographic method for the simultaneous measurement of S‐adenosylmethionine and S‐adenosylhomocysteine concentrations in pig tissues after inactivation of methionine synthase by nitrous oxide
Authors: Molloy Anne M. , Weir Donald G. , Kennedy Glenn , Kennedy Seamus , Scott John M.
Published: May 2005

A rapid gradient method has been established to measure simultaneously the tissue levels of S‐adenosylmethionine (AdoMet) and S‐adenosylhomocysteine (AdoHcy). The method involves application of a 15%–25% linear gradient of methanol over a period of 10 min to an initial mobile phase of 15% methanol with 25 mM sodium phosphate, 10 mM 1‐heptanesulfonic acid solution at pH 3.2 and a flow rate of 1 mL/min. AdoHcy elutes at 9.5 min and AdoMet at 12.6 min. The assay has a detection limit of 10 pmol and is linear in the concentration range 30–800 pmol. The method was used to assess changes in AdoMet and AdoHcy concentrations of pig tissues after seven days exposure to the anaesthetic gas nitrous oxide which irreversibly inactivates methionine synthase and induces an inability to recycle homocysteine, particularly in neural tissues. The treatment caused significant alterations in cellular AdoMet: AdoHcy ratios which were principally due to a dramatic rise in AdoHcy concentrations.
Identification of peroxyacetic acid uroporphyrin I in the urine of patients with congenital erythropoietic porphyria by liquid chromatography and mass spectrometry
Authors: Guo Rong , Rideout J. M. , Chai W. , Lawson A. M. , Lim C. K.
Published: May 2005

A new porphyrin, peroxyacetic acid uroporphyrin I, has been isolated from the urine of patients with congenital erythropoietic porphyria by reversed phase high performance liquid chromatography. The porphyrin was characterized by high resolution mass spectrometry and by typical chemical reactions of a peroxyacid.
Direct diagnosis of tuberculosis by computer assisted pattern recognition gas chromatographic analysis of sputum
Authors: Maliwan Nitaya , Reid Ralston W. , Pliska Stanley R. , Bird Thomas J. , Zvetina James R.
Published: May 2005

Chemical detection of tuberculosis (TB) products in sputum was attempted by using gas chromatographic analysis in conjunction with different pattern recognition computer models. For the chromatographic separations, we used a 2 mm × 1.8 m packed column and a 0.25 mm × 30 m fused silica capillary column to analyse the methylated glycosides and fatty acid methyl ester derivatives. Three computer pattern recognition methods were applied: error score, TB score and discriminant analysis. These methods predicted the presence of active TB most often in sputa of active TB patients and less so in those from inactive, suspected and non‐TB patients, in that order. Although the best true positive of 75% was obtained from the TB score method and best true negative of 98% from discriminant analysis, the accompanying false positive and false negative results (36% and 50%, respectively) were unacceptable. The use of capillary column or fatty acid methyl ester derivatives of the samples did not improve on the predictive values of chromatograms obtained from the packed column on trimethylsilylglycosidic derivatives. Additional work is needed before this method can have a direct clinical application.
Determination of Nifedipine in plasma by a rapid capillary gas chromatographic method
Authors: Guellec C. Le , Bun H. , Giocanti M. , Durand A.
Published: May 2005

A rapid, specific and reliable gas chromatographic assay procedure for Nifedipine in plasma has been developed. With a single‐step solvent extraction, and electron capture detection, the method is sensitive to 0.5 ng/mL of plasma and the standard curve is linear from 0.5 to 500 ng/mL. Samples are protected from light to prevent formation of photodecomposition products. The method has been used to monitor drug concentrations in patients receiving therapeutic doses.
High performance liquid chromatographic determination of 1,5‐anhydroglucitol in human plasma for diagnosis of diabetes mellitus
Authors: Tanaka Shigeo , Nakamori Kota , Akanuma Hiroshi , Yabuuchi Masahiko
Published: May 2005

This paper describes a high performance liquid chromatographic (HPLC) method for determining 1,5‐anhydroglucitol in plasma, in which anion exchange chromatography and pulsed amperometric detection are used. Plasma samples deproteinized with trichloroacetic acid are passed through a three‐layer column packed with (1) strongly basic anion (BO form, the upper layer), (2) strongly basic anion (OH− form, the middle layer) and (3) strongly acidic cation (H+ form, the lower layer) exchange resins. 1,5‐Anhydroglucitol is efficiently recovered in the flow‐through fraction and interfering substances are completely removed by the column treatment. The analytical response of the method is linear with concentration to 40 mg/L, and it is possible to detect as little as 0.1 mg 1,5‐anhydroglucitol per litre of plasma. Analytical recovery is between 96 and 103%, and there is good agreement between the results measured by our method and by a gas/liquid chromatographic method (r = 0.998). The method has been successfully used for the determination of very low 1,5‐anhydroglucitol concentrations (< 1 mg/L) in the plasma of diabetic patients.
Analysis of fragrance compounds in blood samples of mice by gas chromatography, mass spectrometry, GC/FTIR and GC/AES after inhalation of sandalwood oil
Authors: Jirovetz Leopold , Buchbauer Gerhard , Jäger Walter , Woidich Alexander , Nikiforov Alexej
Published: May 2005

After inhalation experiments with sandalwood oil and the pure fragrance compounds coumarin and α‐terpineol, substances were detected and measured in the blood samples of test animals (mice) using gas chromatography/mass spectrometry (GC/MS) (MID) in connection with GC/FTIR (SWC), GC/AES (carbon and oxygen trace) and flame ionization detection/gas chromatography. Using tiglinic acid benzyl ester as the internal standard the following concentrations in serum could be found: α‐santalol 6.1 ng/mL, β‐santalol 5.3 ng/mL and α‐santalene 0.5 ng/mL. In separate inhalation experiments with coumarin and with α‐terpineol the corresponding concentrations were 7.7 ng/mL and 6.9 ng/mL, respectively.
Determination of intraperitoneal mitoxantrone in the serum of cancer patients using a high performance liquid chromatograph coupled to an advanced automated sample processor (AASP)®
Authors: Micelli G. , Lozupone A. , Quaranta M. , Donadeo A. , Coviello M. , Lorusso V.
Published: May 2005

A study has been carried out on 10 patients with ovarian cancer treated by intraperitoneal mitoxantrone. The serum concentration was determined by high performance liquid chromatography with spectrophotometric detection. The extracted analyte on the cartridge was injected and eluted on‐line into the analytical column by the mobile phase. This improved the signal and sample processing rate, without significant loss in analytical performance. Excellent linearity (r >0.9994) was observed for the calibration curve over the range 1–2000 ng/mL, along with a precision within‐day and between‐day estimated as 1.5% and 5.6%, respectively. Sensitivity was an order of magnitude higher than that of the comparison method. From a clinical point of view, these preliminary results have shown that intraperitoneal administration is more beneficial than intravenous therapy. Low serum levels (1–30 ng/mL) with a maximum at the first or second hour are revealed.
High performance ion exclusion chromatographic characterization of the vaginal organic acids in women with bacterial vaginosis
Authors: Stanek Ronald , Glover Douglas D. , Larsen Bryan , Gain Ronald E.
Published: May 2005

Vaginal organic acids have previously been detected by gas–liquid chromatography, but we have applied an ion exclusion high performance liquid chromatographic procedure to the analysis of vaginal discharge samples. This procedure has the advantage of not requiring derivitization of non‐volatile acids and provides the convenience of a technique which does not require the use of flammable gasses, while allowing the identification of at least 18 different acids from the same chromatographic analysis. Vaginal discharge from women with symptoms of bacterial vaginosis was collected on weighed swabs and analysed for the presence of organic acids. The results were compared to the organic acid content of samples obtained from the same cohort of women after treatment with metronidazole. In addition, samples were obtained from asymptomatic women and these samples were analysed in the same manner. The number of organic acids present in samples from women with bacterial vaginosis was greater than the number found after treatment or among asymptomatic women. Succinic acid appeared to be inversely related to lactate concentration and succinate:lactate ratios were greater among women with bacterial vaginosis before treatment than after treatment. Liquid chromatography has proven useful as a means of evaluating the metabolic end‐products of vaginal microorganisms in situ.
Measurement of recombinant interferon levels by high performance immunoaffinity chromatography in body fluids of cancer patients on interferon therapy
Authors: Phillips Terry M.
Published: May 2005

The technique of high performance immunoaffinity chromatography was used to measure the levels of recombinant interferon in chronic lymphocytic leukaemia patients enrolled in a phase II recombinant interferon clinical trial. The technique employed a short high pressure chromatography column packed with minute glass beads which had monoclonal antibody, directed against recombinant alpha interferon, immobilized to their surface. This system was used to measure interferon levels in a variety of different human body fluids. A good correlation was found when interferon levels, detected by chromatographic separation, were compared to levels obtained by a conventional radioimmunoassay.
Hydrophobic interaction chromatography of fibroblast proteoglycans
Authors: Schmidtchen Artur , Fransson Lars‐Åke
Published: May 2005

We have investigated the hydrophobic properties of human skin fibroblast proteoglycans and related material by affinity chromatography on Octyl‐Sepharose CL‐4B in 4 M guanidinium hydrochloride (GdnHCI). Proteoglycans and related material could be separated into non‐, medium and highly hydrophobic forms by elution with gradients of Triton X‐100 in 4 M Gdn HCI. The non‐hydrophobic material included endogenously produced glycosaminoglycan chains and oligosaccharides as well as an HS‐proteoglycan with a 35 kDa core. The 65–70 kDa core (glypican‐related) proteoglycans appeared among the highly hydrophobic ones, but variable proportions were seen both in the medium and the non‐hydrophobic material. Other membrane‐bound proteoglycans, like fibroglycan (45 kDa core) and the HS‐proteoglycans with 90 and 130 kDa cores, as well as the CS/DS‐proteoglycan with a 90 kDa core, were all of high hydrophobicity. There were also indications of a highly hydrophobic CS/DS‐proteoglycan with a 45 kDa core. The extracellular proteoglycans, PG‐L, PG‐S1 and PG‐S2, and the HS‐proteoglycans with 350 and 250 kDa cores were all of medium hydrophobicity. These proteoglycans emerged in distinct positions when the column was eluted with a gradient of 3‐[(3‐cholamidopropyl)dimethylammonio]propanesulphonate.
Determination of felodipine enantiomers using chiral stationary phase liquid chromatography and gas chromatography/mass spectrometry, and the study of their pharmacokinetic profiles in human and dog
Authors: Sakamoto Takashi , Ohtake Yumi , Itoh Motofumi , Tabata Shigeru , Kuriki Takeo , Uno Kazuo
Published: May 2005

A stereoselective and sensitive method for the determination of the enantiomers of felodipine, a dihydropyridine calcium antagonist, has been developed and the pharmacokinetic profiles of the enantiomers comparatively studied after oral administration to dogs and humans. D6‐Felodipine, the internal standard, was added to the plasma, extracted with a solvent and then optically resolved into S(‐) and R(+) enantiomers on a high performance liquid chromatographic Chiralcel OJ column. Each enantiomer in the effluent was analysed by capillary column gas chromatography/positive ion electron impact mass spectrometry. After oral administration of the felodipine racemate, the Tmax and t1/2 values hardly differed between the two enantiomers in dogs and humans. The Cmax and AUC0–24h values of the S(‐) enantiomer were slightly higher than those of the R(+) enantiomer in humans but the difference between the enantiomers was not significant. These results suggested that there is no large difference in the absorption, distribution and elimination of felodipine enantiomers after oral administration of the racemate in either dog or human.
Liquid chromatographic evaluation of purine production in the donor human heart during transplantation
Authors: Smolenski Ryszard T. , Yacoub Magdi H.
Published: May 2005

A reversed phase high performance liquid chromatographic technique is presented allowing purine catabolite determination in a whole blood extract without a prior purification step. The method was applied to determine the timing and the profile of myocardial nucleotide catabolite release during reperfusion of the transplanted human heart. Samples of arterial and coronary sinus blood collected at various times within 1 h after aortic declamping during heart or heart‐lung transplantations were used for nucleotide catabolite determination. Massive release of inosine and hypoxanthine from the heart was demonstrated. Production of adenosine was also shown but there was no liberation of xanthine or uric acid. Nucleotide catabolite release was greatest in the first 5 min (coronary sinus‐arterial difference = 15–20 μM), but was still significant after 30 min of reperfusion. The determination of inosine and hypoxanthine–‐major catabolites released–‐was found to be reproducible in coronary sinus blood (coefficient of variation < 10%). However, immediate protein precipitation afer blood sample collection was necessary, as rapid metabolism of both exogenous and endogenous adenosine and inosine was demonstrated.