Preparative-scale high-performance liquid chromatographic separation and purification of 3'-azido-3'-deoxythymidine-5'-phosphate

Crude 3'-azido-3'-deoxythymidine-5'-phosphate (AZT-P), obtained from direct phosphorylation of 3'-azido-3'-deoxythymidine (azidothymidine, AZT), was separated and purified by isocratic preparative high-performance liquid chromatography. The components in a 2.5-g load of crude AZT-P, obtained from work-up of the phosphorylation reaction, were separated in 50 min to give 1.8 g of 99.5% pure AZT-P. AZT-P was analyzed by high-performance liquid chromatography and by high-resolution nuclear magnetic resonance (1H, 13C, 31P) spectroscopy. The practical and rapid preparative chromatographic method is being applied to the purification of AZT-P and other antiretroviral dideoxynucleotides, used as intermediates in the synthesis of target-directed experimental drugs for the treatment of AIDS.

Localization of CAI and CAII isoenzymes in normal term human placenta by immunofluorescence techniques

The carbonic anhydrase isoenzymes, low activity CAI and high activity CAII, were localized in normal term human placenta by immunocytochemical techniques. Both CAI and CAII isoenzymes were present in the syncytial trophoblasts. Fetal erythrocytes in the placental capillaries also showed positive staining for both CAI and CAII isoenzymes. The possible physiological roles of CA in human placenta are also discussed.

Reversed-phase liquid chromatographic retention and selectivity surfaces. II. Deoxyribonucleosides

By plotting capacity factors and selectivity factors as functions of temperature and pH or methanol concentration of the mobile phase, retention and selectivity surfaces of four deoxyribonucleosides were generated. Although changes in the methanol content had little effect on selectivity, changes in pH and temperature could be used to improve selectivity. However, changes in pH or temperature can be coupled with changes in methanol concentration to optimize the analysis time. In addition, by using lines of constant analysis time (isochrons), it was found that several sets of conditions will result in nearly identical retention times. These isochrons can be used to optimize the resolution of the solutes.

One-step affinity purification of amidase from mutant strains of Pseudomonas aeruginosa

Amidases (acylamide amidohydrolase EC 3.5.1.4) from mutant strains (i.e., B6, AI3, AIU1N, OUCH 4 and L10) of Pseudomonas aeruginosa were purified in one-step by ligand affinity chromatography using Epoxy-activated Sepharose 4B-acetamide. The yields of the purified enzymes were about 90% for all mutant strains with purification factors of about 10 and were apparently homogeneous when analysed by SDS-PAGE and native PAGE. The protein bands on native PAGE coincided with the stained band of enzyme activity for all amidase preparations. Affinity columns had a maximum binding capacity of 0.5 mg amidase protein/ml of sedimented gel and could be regenerated and reused several times without any loss of binding capacity and resolution. Affinity gels containing either semicarbazide or urea were also found useful for the isolation of amidase. The differences in substrate specificity of these amidases reported previously were also observed in the elution behaviour of these enzymes from the affinity columns.

Corky Root of Lettuce Caused by Strains of a Gram-Negative Bacterium from Muck Soils of Florida, New York, and Wisconsin

Slow-growing bacteria similar to the bacterium causing lettuce corky root (CR) in California (strain CA1) were isolated from muck soils of Florida, New York, and Wisconsin, using lettuce seedlings as bait. All strains were tested for reaction with polyclonal antibodies produced against strain CA1 and for pathogenicity on CR-susceptible (Salinas) and CR-resistant (Green Lake) lettuce cultivars in a greenhouse. Five strains from Florida, three from New York, and three from Wisconsin induced severe CR symptoms on Salinas and mild symptoms on Green Lake. All strains were gram-negative, aerobic, oxidase positive, and catalase positive and reduced nitrate to ammonia. Whole-cell fatty acid compositions were similar for all strains and resembled that of Pseudomonas paucimobilis . Since this fatty acid pattern is unique, it is suggested that CR of lettuce is caused by strains of the same bacterium in Florida, New York, Wisconsin, and California.

Analytical-scale high-performance liquid chromatography of omega-3 fatty acid esters derived from fish oils

Fish oil triglycerides were transesterified to their corresponding methyl and ethyl esters. The esters were separated by reversed-phase high-performance liquid chromatography on a 10-cm column of 5-microns octadecylsilyl silica, using a ternary mobile phase of acetonitrile-tetrahydrofuran-water (9:5:11). The separation of principal saturated and unsaturated C14-C22 fatty acid esters was accomplished in 60 min. For the polyenoic acid esters, detection limits of ca. 26 micrograms were observed, and baseline resolution of the important critical pair of esters of the omega 3 fatty acids, eicosapentaenoic acid (C20:5 omega 3) and docosahexaenoic acid (C22:6 omega 3) was achieved. However, to obtain baseline resolution of the esters from minor fatty acid esters, a urea crystallization procedure was required prior to chromatographic analysis. The influence on the reversed-phase chromatographic retention of four different ester moieties on the fatty acids were also studied. The n-alkyl esters exhibited an increase in ln k' with increasing chain length and with increasing lipophilic character of the alkyl ester moieties; however, with the aromatic benzyl derivatives there was a decrease in ln k' compared with the alkyl esters.

Dielectric behavior of aqueous solutions of plasmid DNA at microwave frequencies

The relative permittivity and dielectric loss of aqueous solutions of plasmid (pUC8.c1 and pUC8.c2) DNA have been measured at 20 degrees C over the frequency range 100 MHz-10 GHz. The solutions had a concentration of 0.1% DNA, and were studied both in the relaxed and the supercoiled form. The dielectric measurements were made using a variety of techniques including frequency domain and time domain methods of operation. No evidence of any resonance absorption, nor of any other kind of enhanced absorption, was observed.

Preparative-scale high-performance liquid chromatography of omega-3 polyunsaturated fatty acid esters derived from fish oil

Marine triglyceride-derived omega-3 polyunsaturated fatty acid ethyl esters were separated by preparative high-performance liquid chromatography on a 25-microns octadecyl stationary phase using a ternary isocratic mobile phase of acetonitrile-tetrahydrofuran-water (466:233:300, v/v/v). The highest purity first-run fractions obtained were ethyl esters of the major marine polyunsaturates eicosapentaenoic acid (20:5 omega 3, 97.7%) and docosahexaenoic acid (22:6 omega 3, 93.7%), and the minor polyunsaturate octadecatetraenoic acid (18:4 omega 3, 98.1%).

Liquid chromatographic procedures for the analysis of compounds in the serotonergic and octopamine pathways of lobster hemolymph

High-performance liquid chromatography, with serial electrochemical and ultraviolet detectors, was used with a reduced activity catecholamine C18 column to separate and quantify compounds important in the serotonergic and octopamine pathways in lobster hemolymph. The chromatographic mobile phase was composed of potassium dihydrogenphosphate buffer, trichloroacetic acid, sodium dodecyl sulfate, the sodium salt of ethylenedinitrilotetraacetic acid and the organic solvents, acetonitrile and methanol. The compounds serotonin, 5-hydroxyindoleacetic acid, tryptophan, 5-hydroxytryptophan, tryptamine, melatonin, octopamine and tyrosine were well resolved within 13 min. Good electrode maintenance, the use of a silica gel precolumn and careful sample preparation were necessary to give a stable baseline, high resolution of these compounds and reproducibility of retention times and peak heights. The electrochemical detector extended the range of detection to the picogram level. Because of the instability of the solutes and of the chromatographic baseline, sample preparation procedures were investigated. Deproteinization with ammonium sulfate gave the best recovery of the compounds of interest and the most stable baseline with the electrochemical detector. Peaks in the hemolymph were characterized by addition of standards, dual detection (electrochemical and ultraviolet) and the enzyme peak shift technique. With this methodology, important endogenous neurohormones in the hemolymph of lobsters can be quantitatively determined with respect to the molt cycle.

Factors affecting the performance of an electrochemical detector for the reversed-phase liquid chromatographic separation of small peptides

The factors affecting base line stability of an electrochemical detector (ECD) in the reversed-phase chromatographic separation of peptides are investigated. It is found that the major factor causing base line drift is temperature change. As long as the temperature remains constant, the experiment can be run at ambient temperature +/- 10 degrees C. Other factors affecting the performance of the detector include vibrations, drafts, the use of a chelating agent in the mobile phase, and stirring and recirculating the mobile phase.

Multiple markers for lung cancer diagnosis: validation of models for localized lung cancer

Sera from 71 patients with localized lung cancer, from 70 normal controls, and from 73 patients with benign lung diseases were analyzed for 10 substances to detect lung cancer: ferritin, lipid-bound sialic acid, total sialic acid, beta 2-microglobulin, lipotropin, the alpha and beta subunits of human chorionic gonadotropin, calcitonin (two assays), parathyroid hormone, and carcinoembryonic antigen (CEA). Individual markers were studied, and optimal combinations of markers were sought for discriminating patients with localized lung cancer from normal controls and from patients with benign lung disease. Both logistic regression and recursive partitioning methods for discrimination were tried. The best rules involved only CEA and ferritin for discriminating patients with lung cancer from normal controls, and CEA and age for discriminating patients with lung cancer from those with benign lung diseases. The performance of these rules was validated on an independent serum panel containing sera from 56 patients with localized lung cancer, 75 normal controls, and 75 patients with benign lung diseases. Three rules designed to achieve 95% specificity against normal controls attained 14%-36% sensitivity for localized lung cancer in the validation panels, whereas three rules designed to achieve 95% specificity against benign lung diseases attained 30%-39% sensitivity. Some aspects of potential clinical applications are discussed.

Mutations affecting the synthesis of NADP-dependent glutamate dehydrogenase in Pseudomonas aeruginosa

NADP-dependent glutamate dehydrogenase (NADP-GDH) was purified to homogeneity from Pseudomonas aeruginosa strain 8602 (PAC 1). The Mr determined by Sephadex gel filtration was 280,000; the subunit Mr determined by SDS-PAGE was 45,000. Mutant strains lacking NADP-GDH and glutamate synthase (Gdh-Glt-) required glutamate for growth. Transductants that lacked only NADP-GDH were indistinguishable from the wild-type strain in growth properties. It was concluded that NADP-GDH is not essential for growth of the wild-type organism and that glutamate formation via NAD-dependent glutamate dehydrogenase does not occur to a significant extent. A mutant strain, 39, producing high NADP-GDH activity, synthesized normal NADP-GDH and had the same intracellular glutamate concentrations as its parent. The mutation responsible for the synthesis of high levels of NADP-GDH was shown, by transduction, to be closely linked to the NADP-GDH structural gene (gdhA).

Fast, microbore, and fast microbore high-performance liquid chromatography of nucleic acid constituents

Fast high-performance liquid chromatography (HPLC) (5-10 cm X 4.6 mm I.D. columns), microbore HPLC (25 cm X 2.1 mm and 1 mm I.D. columns), and fast microbore HPLC (5-10 cm X 2.1 mm and 1 mm I.D. columns) were successfully applied to the separation of nucleic acid constituents in standard mixtures and physiological fluids. Separations were obtained in isocratic and gradient elution modes. The separations obtained were compared with those achieved on a conventional 25 cm X 4.6 mm I.D. column. Factors evaluated included separation time, retention time reproducibility, peak height reproducibility, resolution, efficiency, sensitivity and linear response range. Practical factors, such as the amount of sample required and cost per analysis, were also examined.

Microwave absorption in aqueous solutions of DNA

In a recent Nature leading article the possibility of the occurrence of resonance absorption at microwave frequencies in DNA was discussed in terms of the latest available theoretical and experimental evidence, and its implications were assessed. Because of the far-reaching nature of these implications it is important that the existence or otherwise of such absorption be firmly established. Here we report on a concerted effort in two independent laboratories which has involved the measurement of the dielectric properties of aqueous solutions of circular DNA molecules in the frequency range 1-10 GHz. No resonance absorption or any form of enhanced absorption was demonstrated.

Isolation of amidase-negative mutants of Pseudomonas aeruginosa using glycollamide as a selective agent

A positive selection is described for isolating amidase-negative mutants from Pseudomonas aeruginosa strains. The method is based on the conversion, via amidase activity, of glycollamide to glycollate which is growth inhibitory. Three types of mutant were isolated on lactate medium containing glycollamide: (i) mutants in which amidase activity was reduced or absent; (ii) double mutants that were amidase-negative and resistant to glycollate inhibition of growth; and (iii) glycollate-resistant mutants. By raising glycollamide concentrations in the selection medium, amidase-negative mutants were obtained from strains producing altered amidases with low specific acetamidase and glycollamidase activities. Glycollamide has wider applicability than fluoroacetamide as a selective agent for obtaining amidase-negative mutants.

Glycollate inhibition of growth of Pseudomonas aeruginosa on lactate medium

Glycollate inhibited growth of Pseudomonas aeruginosa in media containing either pyruvate or lactate as carbon sources. Glycollamide, but not glyoxylate, showed similar effects. Spontaneous mutants (L/G strains) were isolated that were able to grow on lactate medium in the presence of glycollate: their growth in pyruvate medium was still inhibited by glycollate. Synthesis of membrane-bound NAD+-independent D(-)- and L(+)-lactate dehydrogenase (iLDHs) was inducible by D- or L-lactate in the parent strain but was constitutive in the L/G strains. Glycollate inhibited induction of the synthesis of iLDHs in the parent strain growing in succinate medium but had no effect under the same conditions on strain L/G1. Glycollate was a competitive inhibitor of L(+)-iLDH (Ki = 11 mM). No differences were found in the kinetic properties of L(+)-iLDH in cell-free extracts from strain L/G1 and the parent organism. Glycollate appears to inhibit growth on lactate medium predominantly through prevention of lactate induction of iLDH synthesis.

Development of a microbore high-performance liquid chromatographic system for biological applications

Simple and relatively inexpensive modifications are described for conversion of an existing high-performance liquid chromatographic system to a microbore system capable of isocratic or gradient elution. Use of micro guard columns was shown to be a practical method of protecting the microbore analytical columns when chromatographing samples of physiological origin. The microbore chromatograph was successfully integrated with an autoinjector to permit automation of the system. The modified microbore system was used successfully for the isocratic and gradient separations of standard solutions as well as physiological samples. Evaluation of the system performance was based upon comparisons of column efficiency, selectivity, resolution, and sensitivity.

Micellar liquid chromatography for the analysis of nucleosides and bases

A new high-performance liquid chromatographic method for the analysis of nucleosides and bases was developed in which a micellar mobile phase is used. Separation was achieved on a polyvinyl alcohol (PVA) column by isocratic elution with micellar sodium dodecyl sulfate (SDS) as the mobile phase. The retention behavior of the nucleosides and bases was significantly different from that obtained by reversed-phase chromatography. Effect of pH, temperature, and concentration of SDS and the counter ion (Na+) on retention behavior were investigated. With the PVA column, the best conditions for an isocratic separation were 0.01 M SDS (pH 3.4) and a flow-rate of 2 ml/min at ambient temperature. Mechanisms for the retention of the nucleosides and bases on the PVA column with a micellar mobile phase were proposed and an application of the separation was demonstrated by the analysis of human serum.

High-performance liquid chromatographic profiling of nucleic acid components in physiological samples

The papers reviewed represent recent progress in HPLC profiling of nucleic acid components in physiological samples. Each method was designed for a particular application and possesses certain inherent advantages and/or disadvantages. Many methods are simply modifications of previous procedures. Although some methodologies appear to be superior to others, there is no "best" method for universal usage. The analyst must use the procedure which is best suited for the particular application at hand. This review is meant to be a starting point for the chromatographer who is comparing and evaluating HPLC methods for a given application.

Adenosine's role in regulating basal coronary arteriolar tone

This study examined the role of adenosine in regulating coronary arteriolar tone under basal conditions in the normal coronary circulation. Measurements of hemodynamics and flow (microspheres) were made in eight closed-chest, sedated pigs at 1) control and 2) after 10 min of infusion of adenosine deaminase (ADA, 10 U X kg-1 X min-1) into the left anterior descending (LAD) coronary artery. Heart rate was held constant by atrial pacing. Transmural flow in the distal LAD zone did not change versus control (1.81 +/- 0.36) with ADA (1.78 +/- 0.46). However, in comparison with control the distal LAD:circumflex zone transmural flow ratio (0.96 +/- 0.04) declined (P less than 0.01) during ADA infusion (0.93 +/- 0.04). Similarly, the distal LAD:circumflex zone transmural flow resistance ratio increased significantly (P less than 0.01) versus control (1.04 +/- 0.05) in response to intracoronary ADA infusion (1.08 +/- 0.04). Regional myocardial oxygen consumption in the distal LAD zone did not change versus control (16.9 +/- 3.3 3.3 ml X min-1 X 100 g-1) during ADA (16.9 +/- 4.5). Additional studies in 15 open-chest swine given intracoronary infusion of ADA demonstrated that 1) the enzyme penetrates the interstitial fluid (ISF) and 2) attains ISF levels which are adequate to reduce basal adenosine concentration 10 fold even if substantial increase in adenosine production occurs in response to ADA. Thus, since destruction of adenosine by ADA caused only very modest relative reduction in regional flow, it is likely that the nucleoside plays only a limited role in regulation of arteriolar tone under basal conditions in the normal coronary circulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Multiple markers for lung cancer diagnosis: validation of models for advanced lung cancer

Sera from 171 patients with advanced lung cancer, from 110 normals, and from 123 subjects with benign respiratory diseases were analyzed for 10 substances to detect lung cancer: ferritin, lipid-bound sialic acid, total sialic acid, beta 2-microglobulin, lipotropin, the alpha and beta subunits of human chorionic gonadotropin, calcitonin (two assays), parathyroid hormone, and carcinoembryonic antigen. Individual markers were studied, and optimal combinations of markers were sought for discriminating lung cancer patients from normals and from patients with benign lung disease. Numerous methods for combining the markers were examined, but the methods of logistic regression and recursive partitioning were finally adopted. The best discrimination rules we could find used only carcinoembryonic antigen (CEA) and total sialic acid (TSA). The performance of these rules was validated on an independent serum panel containing sera from 68 patients with advanced lung cancer, from 40 normals, and from 52 patients with benign respiratory disease. The combination rules based on TSA and CEA performed better than a rule based on CEA alone. Logistic discrimination rules with TSA and CEA that were designed to have 95% specificity achieved 54% sensitivity for discriminating advanced lung cancer from normal controls and 52% sensitivity for discriminating advanced lung cancer from controls with benign disease. Some aspects of clinical applicability are discussed, including planned studies for localized lung cancer and the requirement for further testing in specific clinical settings.

Simultaneous high-performance liquid chromatographic assay of the activities of erythrocytic hypoxanthine-guanine phosphoribosyl transferase and purine nucleoside phosphorylase

Hypoxanthine-guanine phosphoribosyl transferase (HGPRTase) and purine nucleoside phosphorylase (PNPase) activities were simultaneously determined in erythrocyte lysates, using the reversed-phase mode of high-performance liquid chromatography. Reaction conditions were developed to provide zero-order kinetics for both enzymes. The activities of the individual enzymes were calculated after incubation of cell lysates with the PNPase substrate, inosine. After sufficient hypoxanthine had been formed to saturate the HGPRTase, the co-enzyme phosphoribosylpyrophosphate and co-factor magnesium (Mg2+) were added to the incubation medium. The enzyme activities were calculated by measurement of the decrease in the PNPase substrate, inosine, and the increase in the HGPRTase product, inosine-5'-monophosphate.

Tomographic digital subtraction angiography: initial clinical studies using tomosynthesis. Work in progress

We have developed a method for acquiring multiple tomographic subtraction images using a rapid, repetitive, circular tomographic motion. The method combines the principles of digital subtraction angiography (DSA) and electronic tomosynthesis. Fifteen patients were examined with the technique using single intravenous bolus injections of contrast material. The image sequence obtained during each injection was first processed with a nontomographic mask subtraction, and the result was then compared with the tomographic DSA scans synthesized from the same sequence. The effective section thickness was approximately 0.5 cm, with each section being 0.5-1.0 cm apart. Twelve of the intravenous DSA scans provided the necessary diagnostic or clinically useful information. Two of the three nondiagnostic scans were caused by avoidable technical reasons. In eight cases, the tomographic DSA scans were superior in quality to the nontomographic scans, exhibited significantly less artifact from patient motion and overlying bowel gas, and were effective in separating overlapping vessels. Tomosynthesis permits multiple electronic imaging of the area of interest without reinjection of contrast material and appears to be more informative than nontomographic intravenous DSA imaging.

Evaluation of HPLC column performance for clinical studies

Several C18 HPLC columns, varying in column length as well as packing material diameter, were used to separate mixtures of biochemical compounds in standards and in various physiological fluids. The column performances were compared both qualitatively and quantitatively. Factors investigated included efficiency, resolution, selectivity, column effect on peak height, temperature effects, cost per analysis, and analysis times. Column lifetime was also examined. The results were used to evaluate the suitability of the various columns for use in the chromatographic analysis of physiological samples.

The platelet defect in acute myeloid leukaemia

In a study of platelets from 13 patients with acute myeloid leukaemia abnormal aggregation and release reactions were found. A previously unrecognised quantitative defect of thromboxane B2 production may, at least in part, explain these findings. In contrast to a previous report, we were unable to show a convincing storage pool defect in these platelets. The platelet membrane glycoproteins were largely normal.

Operative myocardial protection: does an elevated level of creatine phosphokinase-MB isoenzyme always indicate myocardial necrosis?

Creatine phosphokinase-MB isoenzyme appears in the serum of virtually all patients who have undergone cardiac operations, but whether it represents myocardial cellular necrosis remains controversial. In 17 adult patients who underwent coronary artery bypass grafting or valve replacement, serial determinations of the serum levels of creatine phosphokinase-MB isoenzyme, ultrastructural studies of left ventricular myocardium before aortic cross-clamping and 10 minutes after reperfusion and postoperative electrocardiographic recordings were undertaken. The isoenzyme was detected in all patients; those having valve replacement had higher peak values than those who underwent coronary artery bypass grafting. No correlation was found between the duration of aortic cross-clamping and the peak level of isoenzyme after reperfusion. In spite of appreciable isoenzyme release from the myocardium, all the specimens obtained from this series of patients after reperfusion showed myocardial ultrastructural changes indicative of mild to moderate ischemic damage, considered to be reversible according to the criteria described by Jennings and Schaper. Except for one new Q wave, electrocardiographic changes in this series were nonspecific and transient. It is postulated that when sufficient myocardial mass is involved, such as in global ischemia during cardiac surgery, the MB isoenzyme of creatine phosphokinase leaked from reversibly damaged myocytes may become detectable and elevated in the serum. Thus, although the isoenzyme remains a sensitive indicator of myocardial protection, its presence does not necessarily indicate irreversible damage and myocardial necrosis.

Distribution of cat allergen 1 in cat tissues and fluids

The distribution of the major allergen of the domestic cat, cat allergen 1, was studied in 22 different tissues obtained from a male and female cat and in samples of saliva and urine. Of the cat tissues studied, only extracts of pelt and female brain contained amounts of cat allergen 1 in excess of 0.50 U/ml. Smaller amounts of cat allergen 1 were found in extracts of eye, thyroid, ovary, sublingual gland and large intestine. Unstimulated cat saliva contained a mean of 1.08 U/ml cat allergen 1. Saliva stimulated with ketamine HCl alone, or with ketamine HCl plus pilocarpine, contained 0.68-8.16 U/ml cat allergen 1. In all of the stimulated saliva collections, the total quantity of cat allergen 1 obtained was relatively constant (between 40 and 80 U). These results suggested that the elaboration of cat allergen 1 in saliva is independent of parasympathetic control. Cat allergen 1 could only be detected in cat urine that had been concentrated 9-fold in concentrations of less than 0.5 U/ml. The above results support the hypothesis that the major source of cat allergen 1 is the saliva, and that the presence of cat allergen 1 in the pelt is due to deposition of the allergen during grooming.

High performance liquid chromatographic profiles of nucleosides, bases and tryptophan in the plasma of the Tasmanian devil and four other marsupial species

Plasma profiles of nucleosides, bases and trytophan of five marsupial species were established using the reversed-phase mode of high performance liquid chromatography (RHPLC). Within each species, the profiles were highly reproducible and between species there were distinct differences. In the Tasmanian devil, the circulating levels of constituents examined with one exception, were generally lower than in the other marsupials. The exception was a constituent present in large amounts and having the characteristics of a purine nucleoside derivative which was found only in the plasma of the devil.

Liquid chromatographic profile classification of acute and chronic leukemias

Reversed-phase high performance liquid chromatography and multivariate discriminant analysis are used for the classification of acute and chronic leukemias. Plasma or serum profiles, mainly of nucleosides, bases, and aromatic amino acids, are segmented into specific retention time intervals. Peak areas in each retention time interval are summed such that the chromatographic profile can be represented as a pattern vector formed from the linear combination of peak areas. The preprocessing techniques of autoscaling and variance weighting minimized inadvertent weighting and reduced the contribution of nondescriptive data components in the development of the discriminant function. The acute lymphocytic leukemia plasma samples and controls were classified with 100% sensitivity and specificity. Chronic leukemia serum samples and controls were categorized with sensitivity and specificity values of 93.7 and 87.6%, respectively.

Current high performance liquid chromatographic methodology in analysis of nucleotides, nucleosides, and their bases. II

This review of HPLC technology is presented in two parts, the first of which appeared in Volume 1, Number 5 of this journal. Part I presented an introduction to chromatography, sample preparation, and basic information on chromatographic theory and terminology, modes, and instrumentation. Also covered in Part I was a discussion of stationary and mobile phase parameters which can be varied to optimize separations. Part II of the review which follows covers peak identification, quantification, and selected applications of HPLC for metabolic profiling, for assays of adenosine and cyclic nucleotides in studies of disease processes and for enzyme assays. The paper concludes with a short discussion of future trends for HPLC in biomedical research and clinical chemistry.

Current high-performance liquid chromatographic methodology in analysis of nucleotides, nucleosides, and their bases. I

This review of HPLC technology is presented in two parts. An introduction to chromatography, sample preparation, and basic information on chromatographic theory and terminology, modes, and instrumentation is presented here. A discussion of stationary and mobile phase parameters which can be varied to optimize separations is also presented here. The second part of the review, which will appear in the next issue, will cover peak identification, quantification, and selected applications. The applications include short discussions of applications of HPLC for metabolic profiling, for assays of adenosine and cyclic nucleotides in studies of disease processes, and for enzyme assays. The paper concludes with a short discussion of future trends for HPLC in biomedical research and clinical chemistry.

Reversed-phase liquid chromatographic investigation of UV-absorbing low-molecular-weight compounds in saliva

The reversed-phase mode of high-performance liquid chromatography was used to determine the intra- and inter-individual levels of UV-absorbing low-molecular-weight compounds in saliva. Many of the compounds known to occur in serum were also found in saliva; however, concentrations in saliva are lower. Both the intra- and inter-individual levels of these compounds vary significantly; in most cases, the inter-individual variance is 2-3 times the intra-individual variance. Caffeine and its metabolites in saliva are also reported. A greater number of metabolites were found in the saliva of habitual coffee drinkers. After caffeine was administered orally, paraxanthine, theobromine, theophylline, 1-methylxanthine, and 1-methyluric acid were found in the saliva of an individual who did not drink coffee regularly. In this subject, the serum half-life for caffeine was 3.49 h and the saliva half-life was 3.27 h. The half-life of caffeine in an habitual coffee drinker who had refrained from caffeine products for four days was 4.39 h.

HPLC analysis of aromatic amino acids, nucleosides, and bases in plasma of acute lymphocytic leukemia on chemotherapy

Plasma chromatograms--obtained by the reversed-phase mode of high performance liquid chromatography (HPLC)--of 19 subjects with acute lymphocytic leukemia (ALL) were compared to those of 19 normal individuals. ALL patients were in remission and on a methotrexate and 6-mercaptopurine maintenance regimen. The concentrations of the aromatic amino acids L-phenylalanine and L-tyrosine, the nucleosides uridine, adenosine, inosine, and guanosine, as well as the bases hypoxanthine and xanthine, were elevated in the leukemic in comparison to the normal chromatograms. Highest inosine levels corresponded to leukemic subjects whose condition severely deteriorated with time. Patients with lower inosine levels are still in continuous remission.

Rapid assay for plasma chlorambucil and phenyl acetic mustard using reversed-phase liquid chromatography

A rapid assay for chlorambucil, a drug used for the treatment of chronic lymphocytic leukemia, and its major metabolite is described. Chromatographic behaviour of the two compounds on two different reversed-phase columns is discussed, as well as the kinetics of their hydrolysis in aqueous medium. The developed analysis can be applied to the determination of the plasma levels of the drug and its metabolite. No sample preparation is required and the spectrophotometric detection affords the sensitivity in the picomole range. Total analysis time is between 10 and 15 min.

Growth of Pseudomonas aeruginosa mutants lacking glutamate synthase activity

Mutant strains SU1, SU4, and US1 lacking glutamate synthase (GOGAT) activity were isolated from strains of P. aeruginosa for which histidine is a growth rate-limiting source of nitrogen. Strains SU1 and SU4 were unable to grow when a low concentration of ammonia and a variety of compounds, including histidine, were supplied as sole sources of nitrogen. A revertant of strain SU1, strain 39, produced no GOGAT but high levels of nicotinamide adenine dinucleotide-dependent glutamate dehydrogenase and had restored ability to grow on a limited number of nitrogen sources. Strain US1 grew at the same rate in histidine medium as did its parent; it was derepressed for glutamine synthase synthesis, and histidase was less sensitive to repression by ammonia than in the parent strain. We conclude that GOGAT is not essential for growth on histidine but high levels of glutamine synthase are required nd high levels of nicotinamide adenine dinucleotide-dependent glutamate dehydrogenase can sustain growth at low concentrations of ammonia in the absence of GOGAT.

The rapid determination of erythrocyte porphyrins using reversed-phase high performance liquid chromatography

The extraction, separation and quantification of free acid erythrocyte porphyrins are described. The porphyrins are extracted from whole blood using 3:1 ethyl acetate/acetic acid (v/v) and separated using the reversed-phase mode of high performance liquid chromatography (RPLC). The compounds are detected on-line spectrofluorometrically using an excitation wavelength of 404 nm and an emission cut-off filter of 550 nm. Excellent resolution of the porphyrin free acids is achieved in less than 6 min. The analytical recoveries for protoporphyrin IX and zinc protoporphyrin IX were greater than 90% with relative standard deviations for day-to-day analysis under 6%.

Optimized assay for purine nucleoside phosphorylase by reversed-phase high-performance liquid chromatography

The reversed-phase mode of high-performance liquid chromatography (HPLC) was used to assay purine nucleoside phosphorylase (PNPase E.C. 2.4.2.1) in human erythrocytes. The reaction conditions were optimized with respect to pH, concentration of enzyme, concentration of substrate and time. In this method, a sample of erythrocytes was incubated with substrate and necessary cofactors. After termination of the reaction, both the decrease in substrate and the increase in product were measured. HPLC is highly suitable for PNPase as both the forward and reverse reactions can be monitored. The complete separation of products from reactants allows the determination of any competing or side reactions.

Adaptation to phenylacetamide as a growth substrate by an acetanilide-utilizing mutant of Pseudomonas aeruginosa

Mutants able to utilize phenylacetamide as sole nitrogen source were isolated from the acetanilide (N-phenylacetamide) - utilizing Pseudomonas aeruginosa mutant strain A13 and from its parent strain L 10. Growth properties of the mutants (Ph strains) on amide media and the physicochemical properties of their amidases in cell free extracts indicated that their phenylacetamidase activities were attributable to alterations in their amidases. Differences in amide hydrolase specificities between the AI3- and the L 10-Ph mutants were observed. The AI3 group had a high level of activity towards 4-nitrophenylacetamide, activity towards phenylacetyl-4-nitroaniline but, unlike strain AI3, no activity towards acetyl-4-nitroaniline; the L 10 group had a low activity towards 4-nitrophenylacetamide, no activity towards phenylacetyl-4-nitroaniline but retained the low level of activity towards acetyl-4-nitroaniline exhibited by strain L 10. Confirmation of the association between these altered specificities and alterations in amidases was obtained from analysis of the properties of phenylacetamidases purified from an AI3-Ph mutant (pH 5) and an L 10-Ph mutant (Ph14). The original mutation in the amidase gene of strain AI3 appeared responsible for the differences between the two groups of Ph mutants and the binding interactions with acetanilide that it determined were eliminated in AI3-Ph mutants.

Comparison of high-performance liquid chromatographic serum profiles of humans and dogs

The sera of 30 healthy male beagles were analyzed by reversed-phase high-performance liquid chromatography. The profiles were compared with those obtained from the sera of 30 healthy human donors. The chromatograms of each group were very reproducible; however, there were characteristic differences between the two groups. The compounds observed in both the human and canine profiles were identified as creatinine, uric acid, tyrosine, hypoxanthine, xanthine, kynurenine, inosine and tryptophan. Compounds present only in the canine profiles were identified as cytindine, riboflavin and 5-methyl-cytidine. Compounds present only in the human profiles include uridine, guanosine, hippuric acid and the dietary dependent compounds theobromine and caffeine. The compounds present in both human and canine sera were quantitated and compared statistically. The amounts of these compounds were very similar, except for uric acid.

Tegument-associated antigen modulation by adult male Schistosoma mansoni

Adult Schistosoma mansoni from mice were incubated in rabbit anti-mouse immunoglobulin class or subclass-specific sera. The rabbit antibody binding was then visualized by incubation of the labeled worms in fluoresceinated Staphylococcus aureus, which associated with the Fc portion of the rabbit antibody molecule by means of bacterial cell wall Protein A. The assay system was found to be simple, inexpensive, specific, repeatable, and rapidly accomplished. By using this technique, previous work documenting the presence of mouse IgG1, IgG2a, IgG2b, IgG3, IgA, and IgM on the tegumental surface of adult worms of mouse origin was confirmed. It was further confirmed that the complexing of rabbit antibody to the mouse antigen led to the shedding of that antigen from the parasite's surface membrane within 20 min at 37 degrees C. This shedding phenomenon was specific for only those antigens interacting with the ligand and was inhibited by incubation with sodium fluoride, 2-deoxy-D-glucose, cytochalasin B, cytochalasin D, caffeine, or at 4 degrees C. These data indicate a sophisticated control mechanism exercised by the parasite over its interface with the host and may indicate a complexity of the host-parasite relationship not heretofore recognized.

Tegument-associated antigen modulation by adult male Schistosoma mansoni

Adult Schistosoma mansoni from mice were incubated in rabbit anti-mouse immunoglobulin class or subclass-specific sera. The rabbit antibody binding was then visualized by incubation of the labeled worms in fluoresceinated Staphylococcus aureus, which associated with the Fc portion of the rabbit antibody molecule by means of bacterial cell wall Protein A. The assay system was found to be simple, inexpensive, specific, repeatable, and rapidly accomplished. By using this technique, previous work documenting the presence of mouse IgG1, IgG2a, IgG2b, IgG3, IgA, and IgM on the tegumental surface of adult worms of mouse origin was confirmed. It was further confirmed that the complexing of rabbit antibody to the mouse antigen led to the shedding of that antigen from the parasite's surface membrane within 20 min at 37 degrees C. This shedding phenomenon was specific for only those antigens interacting with the ligand and was inhibited by incubation with sodium fluoride, 2-deoxy-D-glucose, cytochalasin B, cytochalasin D, caffeine, or at 4 degrees C. These data indicate a sophisticated control mechanism exercised by the parasite over its interface with the host and may indicate a complexity of the host-parasite relationship not heretofore recognized.

Identification and quantitation of nucleosides, bases and other UV-absorbing compounds in serum, using reversed-phase high-performance liquid chromatography. II. Evaluation of human sera

The reversed-phase mode of high-performance liquid chromatography was used to investigate the profiles of low-molecular-weight, UV-absorbing compounds in human serum. Identification techniques are described which allow for the identification of picomole amounts of the nucleosides, bases and other compounds in several microliters of serum ultrafiltrate. The sera from 31 normal subjects (17 males, 14 females) showed very consistent profiles. A total of 12 compounds were identified and quantified in normal serum. The analysis of sera from over 150 patients with various types of neoplasia and other diseases showed serum profiles significantly different from normal profile.