bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gas-chromatographic micro-scale procedure for theophylline, with use of a nitrogen-sensitive detector.
Authors: Least C J , Johnson G F , Solomon H M 
Published: January 2020

Abstract
We report a micro-scale procedure for determination of theophylline by use of gas chromatography with nitrogen-sensitive detection. The procedure requires only 10 mul of serum, plasma, or saliva. This sample size makes the determination especially appropriate for monitoring in a pediatric population. With the sample volume used, background interference is equivalent to about 0.1 mg/liter and 0.5 mg of theophylline per liter can easily be measured. The new method correlates well with our earlier flame ionization gas-chromatographic procedure that required 1 ml of sample [Clin. Chem. 21, 1038 (1975)]. The selectiviey of the nitrogen detector allows a simplified extraction procedure. Between-run precision (CV) is 2.8% at a theophylline concentration of 14.8 mg/liter.
Gas-chromatographic determination of 5-fluorocytosine in human serum.
Authors: Harding S A , Johnson G F , Solomon H M 
Published: January 2020

Abstract
We describe a sensitive and precise gas-chromatographic method, in which cytosine is used as the internal standard, for determination of an antifungal agent, 5-fluorocytosine, in serum. The trimethylsilyl derivative of this drug is well separated from the internal standard and from normal serum constituents. Amphotericin B does not interfere with the determination of 5-fluorocytosine. The lower limit of detection for 5-fluorocytosine is 1 mg/liter when 200 mul of serum is analyzed. Within-run precision (CV), established by analysis of 10 replicates, was 4.5% at a concentration of 19.9 mg/liter. Twenty-five serum samples were analyzed for 5-fluorocytosine by a microbiological assay and by the gas-chromatographic method. Mean value observed with the bioassay was 78.5 mg/liter and with our procedure was 69.4 mg/liter. When values for our assay were regressed against values for the bioassay, slope of the least-squares line was 0.85, intercept was 2.7 mg/liter, and r was 0.93.
Gas-chromatographic determination of an antifibrinolytic drug, epsilon-aminocaproic acid.
Authors: Keucher T R , Solow E B , Metaxas J , Campbell R L 
Published: January 2020

Abstract
We describe a modified method for assay of epsilon-aminocaproic acid. Serum or cerebrospinal fluid is deproteinized, followed by cation-exchange column-chromatography, and N-trifluoroacetyl-n-butyl derivatives of amino acids are formed and separated by gas chromatography. Tranexamic acid, a nonprotein amino acid, was used as an internal standard. The assay is sensitive and precise, and results correlate adequately with those obtained with an automated amino acid analyzer (ion-exchange chromatography).
Radioimmunoassay for clindamycin.
Authors: Gilbertson T J , Stryd R P 
Published: January 2020

Abstract
We describe a radioimmunoassay for measuring clindamycin in serum extracts that is more accurate than the microbiological assay because of the minimal response of the matabolite, N-demethylclindamycin. The assay is not affected by the presence of other antiobiotics. As described it is as sensitive as the microbiological assay, but can be made more sensitive.
Analysis of results of toxicological examinations performed by coroners' or medical examiners' laboratories in 2000 drug-involved deaths in nine major U. S. cities.
Authors: Dinovo E C , Gottschalk L A , McGuire F L , Birch H , Heiser J F 
Published: January 2020

Abstract
Data were collected on 2000 deaths in which psychoactive drugs were involved. The data were submitted by medical examiners or coroners in nine U. S. cities from their case files. The 2000 cases comprise a representative sample from each of these cities of deaths from psychoactive drugs between 1972 through 1974. This report details inter-city differences in methods and practices of the toxicological examination as well as the type and numbers of drugs reported. Even when the same analytical method was used in various cities, there were differences in extraction solvent and extraction pH. Of the 3909 drugs detected, 2945 were quantitated; the number of drugs quantitatively measured per case studied ranged from a low of 0.82 for New York to a high of 2.20 for Washington, D.C. The number of different drugs quantitatively measured varied from 16 for New York to 30 for San Francisco; however, New York qualitatively assayed for the presence of a total of 25 drugs. The number and type of drugs found per case varied. Methadone, for example, was found in 60% of the cases reported by New York and in 49% of the cases from Washington, D.C., but in only about 10% of cases reported by Philadelphia, Dallas, Miami, and San Francisco, and in less than 1% of Los Angeles and Cleveland cases; it was not reported by Chicago. Phenmetrazine-caused deaths were reported only by Dallas (one case) and Washington, D.C. (29 cases). From the data as a whole, information is presented for 33 drugs as to the concentration in physiological tissues and fluids. Analysis of single psychoactive drug cases and single-drug-plus-ethanol cases shows that, in the presence of ethanol, the toxic blood concentration of imipramine, amytriptyline, meprobamate, thioridazine, morphine, propoxyphene, methaqualone, and all barbiturates was decreased by an average of 50%.
Rapid micromethod for measuring anticonvulsant drugs in serum by high-performance liquid chromatography.
Authors: Soldin S J , Hill J G 
Published: January 2020

Abstract
We describe an assay system for measuring phenobarbital, diphenylhydantoin, primidone, ethosuximide, and carbamazepine in 25 mul of serum. The procedure involves precipitation of proteins with an acetonitrile solution containing cyheptamide as an internal standard, and reverse-phase chromatography on a 4 mm X 30 cm column containing "muBondapak C18." The anticonvulsants are eluted with an equivolume mixture of potassium phosphate buffer (10 mmol/liter, pH 8.0) and acetonitrile at a flow rate of 0.8 ml/min, detected by their absorbance at 200 nm, and quantitated by measuring peak areas. When measurement of primidone is not required, a 254-nm detector may be used. Each analysis requires 10 min. Optimum column temperature has been found to decrease with use. Analytical recoveries for the five drugs varied from 92% to 102% with good precision (coefficients of variation between 2.8% and 9.2% for therapeutic and toxic concentrations). The results obtained with this method compare favorably with results obtained by gas-liquid chromatography (correlation coefficients between 0.77 and 0.98). In over 1300 patients' samples analyzed to date, the only drugs known to have interfered with the assay are gentamicin, diazoxide, and mephobarbital.
Method for alcohol determination in biological liquids by sensing with a solid-state detector.
Authors: Dubowski K M 
Published: January 2020

Abstract
I describe a new method for quantitative alcohol determination in equilibrated headspace gas of biological liquids by means of a solid-state metal-oxide semiconductor (MOS) detector. After equilibration of the NaCl-saturated specimen at 40 degrees C or other convenient temperature in a closed vessel, a Taguchi MOS sensor is momentarily exposed to the headspace vapor. The resulting dc voltage change from the baseline conditions accurately reflects the alcohol concentration of the liquid specimen, and can be read in direct alcohol-concentration units. Calibration is linear to 3.00 g/liter (300 mg/dl). Values for analytical recovery ranged from 98 to 102%. Correlation of results for blood alcohol concentration by this method (yi) and an automated gas-chromatographic reference method (xi) was y, g/liter = 0.991x + 0.014, with r = 0.997 for 103 blood specimens having concentrations ranging from 0 to 2.89 g/liter (0-289 mg/dl), with a mean difference (xi - yi) - -6 mg/liter (0.6 mg/dl). The method is sensitive to 0.01 g/liter (1 mg/dl) and can be readily automated. An internal standard is not required.
Diazepam abuse: incidence, rapid screening, and confirming methods.
Authors: Rejent T A , Wahl K C 
Published: January 2020

Abstract
We studied 2500 patients suspected to be drug-overdose victims. Blood samples were quantitatively screened for the most commonly abused drugs, including diazepam. Of these, 61% had positive findings, including diazepam in about one of every four. A new rapid, simple, and quantitative gas-chromatographic method for simultaneous analysis of diazepam and sedatives (in two instruments) is described. A single extraction at low pH is used, preserving the balance of the sample to be used for confirming methods via ultraviolet spectrophotometry and thin-layer chromatography. Prevalance of other positive findings is also listed, and findings for diazepam are categorized by age.
Improved micro-radioimmunoassay of digoxin in serum, with use of 125I-labeled digoxin.
Authors: Calesnick B , Dinan A 
Published: January 2020

Abstract
A micro-radioimmunoassay of 125I-labeled digoxin is described in which 10-mul rather than 50-mul aliquots of sera are required. The method is a modification of a simplified, rapid, and accurate procedure, which is commercially available as a kit. There is excellent correlation between results by these two methods, in which lyophilized digoxin standards and insoluble antibody polymer are used. The digoxin concentration in capillary sera was not significantly different from that in the corresponding venous blood. It is clinically useful to monitor digoxin therapy in capillary sera, particularly in patients in whom blood sampling by venipuncture is inconvenient or difficult.
Determination of carbamazepine in blood or plasma by high-pressure liquid chromatography.
Authors: Kabra P M , Marton L J 
Published: January 2020

Abstract
We described a sensitive and precise high-pressure liquid-chromatographic method in which 5-(p-methylphenyl)-5-phenylhydantoin is used as the internal standard in determining carbamazepine in whole blood or plasma. Carbamazepine is well separated from normal blood constituents in less than 8 min, and other commonly used anticonvulsants do not interfere with the analysis. The sensitivity of this method is adequate to quantitate 0.25 mg of carbamazepine per liter in 2 ml of sample, and the lower limit of detection is 100 ng. Twenty specimens were analyzed by a gas-chromatographic method and by the present method; the resulting correlation coefficient was greater than .980.
Evaluation of adenosine 5'-monophosphate and fluoride as adenylate kinase inhibitors in the creatine kinase assay.
Authors: Rosano T G , Clayson K J , Strandjord P E 
Published: January 2020

Abstract
Adenylate kinase (EC 2.7.4.3) interferes positively in the serum creatine kinase (EC 2.7.3.2) assay when the rate of ATP production is monitored by a coupled enzyme system. A dual assay, measuring creatine kinase and adenylate kinase activity, was used to evaluate AMP and other possible adenylate kinase inhibitors that would permit specific measurement of creatine kinase activity in the presence of adenylate kinase. We found that AMP, routinely included in the creatine kinase assay system to inhibit adenylate kinase, partially inhibits both human serum creatine kinase and purified creatine kinase from rabbit muscle. The amount of creatine kinase inhibition is related directly to the AMP concentration and inversely to the substrate (ADP) concentration. We found that 25 mmol/liter of fluoride inhibits adenylate kinase without measurable effect on creatine kinase activity. We developed a serum creatine kinase assay including fluoride, and compared it with the dual assay system and with two commercial assay kits. Other halides or adenosine 2'-monophosphate did not selectively inhibit adenylate kinase.
Rate of decay and distribution volume of MB isoenzyme of creatine kinase, intravenously injected into the baboon.
Authors: Yasmineh W G , Pyle R B , Nicoloff D M 
Published: January 2020

Abstract
We determined the decay constant and distribution space of the MB isoenzyme of creatine kinase after intravenous injection of 440 to 720 U, in a group of seven adult baboons. The rate of decay of the isoenzyme was monoexponential, with a mean decay constant of 0.00175 min-1 (SD, 0.00019). The mean distribution volume obtained by extrapolation of the monoexponential curve to zero time was 5.22% (SD, 1.06) of body weight. We have determined these parameters with the purpose of using this isoenzyme in the baboon as an experimental model for measuring myocardial infarct size.
Direct use of ion-exchange papers in hemagglutination-inhibition tests for drug abuse.
Authors: Alexander G J 
Published: January 2020

Abstract
I modified a procedure for screening urine specimens for evidence of drug abuse, to permit direct use of commercially available ion-exchange papers in hemagglutination-inhibition assay for drug detection. Small circles punched out of the papers, which previously had been impregnated with drug-containing urine, were used in the detection step, leaving the remainder of the specimens on paper available for confirmatory analyses. The procedure is useful in screening for the presence of opiates, methadone, and (or) barbiturates.
Alkaline phosphatase. II. Conditions affecting determination of total activity in serum.
Authors: Van Belle H 
Published: January 2020

Abstract
Results of previous experiments on isolated purified isoenzymes of alkaline phosphatase from humans have been confirmed on sera containing relatively large activities of the different isoenzymes. The most remarkable finding is that activation by N-ethylaminoethanol is much more pronounced, in the case of the intestinal and placental isoenzymes, than is activation by diethanolamine. For several reasons, it is suggested that N-ethylaminoethanol is the buffer of choice, 0.1 mol/liter concentration for routine measurements and 1 mol/liter in those cases where the determination of the intestinal or placental isoenzymes is important. Mg2+ could be omitted because its addition increases the activity only marginally. Normal values for adults with use of 0.1 mol/liter N-ethylaminoethanol are 59 +/- 36 (2 SD) U/liter (n = 126).
Immunofixation electrophoretic techniques applied to identification of proteins in serum and cerebrospinal fluid.
Authors: Cawley L P , Minard B J , Tourtellotte W W , Ma B I , Chelle C 
Published: January 2020

Abstract
We describe the application of immunofixation staining of agarose-gel electrophoretograms in areas where its use in the clinical laboratory is appropriate. Immunofixation electrophoresis consists of an electrophoretic phase followed by a fixation phase in which antiserum is used to precipitate the protein. As long as the antibody is in slight excess or near equivalency, the antigen/antibody complex remains insoluble. The reaction can be detected by visual inspection in indirect light, by protein staining, or by use of antibodies labeled with fluorescein, enzyme, or isotope. In the method described here we primarily have used protein staining (Coomassie Blue) to accentuate the proteins fixed by antisera. All unreacted proteins are removed by pressing with filter paper and saline washing. In the clinical laboratory, this method expedites immunochemical evaluation of samples and may also supplement immunoelectrophoresis. It has been applied successfully in identifying small obscure monoclonal proteins in the serum and cerebrospinal fluid of patients with multiple sclerosis, subacute sclerosing panencephalitis, biclonal gammopathies, serum monoclonal light chains, and mobility shifts of certain proteins, particularly of the complement series. Immunofixation demonstrates that the protein bands present in spinal fluid from multiple sclerosis and subacute sclerosing panencephalitis patients are of the IgG class of immunoglobulins; and non-IgG protein, such as beta and gamma trace proteins, are not detected. We also comment on reverse immunofixation with labeled antigen as a branch of the procedure that allows detection of function of the immunoglobulins separated by electrophoresis.
Urinary organic acids in man. III. Quantitative ranges and patterns of excretion in a normal population.
Authors: Chalmers R A , Healy M J , Lawson A M , Hart J T , Watts R W 
Published: January 2020

Abstract
We studied the urinary excretion of organic acids by normal human subjects in an ambulant normal population, chosen without conscious bias. Quantitative ranges and frequency distribution patterns of excretion are reported, as a basis on which to compare results obtained for patients whose clinical condition suggests that their excretion values may be abnormal. The quantitative valuse we observed enable the relative significance of different urinary anionic metabolites to be assessed, including the recently identified aldonic and deoxyaldonic acids. The frequency distribution patterns observed are discussed briefly.
Purification of alpha1-fetoprotein.
Authors: Twomey S L , Sweet R V 
Published: January 2020

Abstract
Previously published methods for purifying alpha1-fetoprotein are inadequate because they either do not yield a completely pure product or they cause some denaturation. We present a method that does not have these serious disadvantages, and with which alpha1-fetoprotein was purified by sequential use of concanvalin A affinity-chromatography, preparative gel-electrophoresis, and immunoabsorption with anti-albumin antibody covalently coupled to Sepharose 4B. The purity of the product was monitored by discontinuous polyacrylamide-gel electrophoresis and counterimmunoelectrophoresis, both of which must be used to ascertain what proteins are present at each step of the purification.
Simplified, totally enzymatic method for determination of serum triglycerides with a centrifugal analyzer.
Authors: Grossman S H , Mollo E , Ertingshausen G 
Published: January 2020

Abstract
We describe a totally enzymatic method for determination of serum triglycerides (triacylglycerols) specifically adaptable to the CentrifiChem system. The method involves lipolysis with lipase from Rhizopus arrhizus alone and quantitation of the resulting glycerol with glycerol dehydrogenase in a kinetic, fixed-time mode. Hydrolysis by the lipase is complete, for concentrations up to at least 5.0 g/liter, in 10 min at room temperature. The unfavorable equilibrium for the oxidation of glycerol is overcome by increasing the pH and adding excess NAD+. Under these conditions the glycerol determination is linear to at least 4.0 g of glycerol per liter, as triglyceride. The test exhibits acceptable accuracy and precision, and results correlate well with those by an alternative totally enzymatic procedure. The present method is unaffected by phosphatase and a considerably simplified reagent is used.
Rapid-flow enthalpimetric determination of urea in serum, with use of an immobilized urease reactor.
Authors: Bowers L D , Canning L M , Sayers C N , Carr P W 
Published: January 2020

Abstract
We used a differential thermal detector in conjunction with an immobilized urease reactor to determine urea in serum. Samples (120 mul) are introduced into a flow stream and passed through an "adiabatic" column, which is packed with enough insolubilized urease to completely convert urea to ammonia and carbon dioxide. Measured temperature changes are directly proportional to the serum urea concentration. Urea in the presence of protein, bilirubin, and hemoglobin can thus be rapidly, simply, and inexpensively measured. Results correlate well with those obtained by the manual diacetyl monoxime and urease/indophenol methods.
Propoxyphene and norpropoxyphene concentrations in blood and tissues in cases of fatal overdose.
Authors: McBay A J 
Published: January 2020

Abstract
Propoxyphene and its major metabolite, norpropoxyphene, have been quantitated in tissue specimens obtained from autopsies of people suspected of dying from propoxyphene overdosage. Gas-chromatographic determination of both propoxyphene and norpropoxyphene is essential because the blood concentration of the parent drug should be about 1.0 mg/liter or greater to attribute a death to the drug. The metabolite concentration in blood may help to establish when the drug was ingested. Concentrations in the blood after high oral therapeutic doses are about 0.3 mg of propoxyphene per liter, and norpropoxyphene concentrations may be as high as 3 mg/liter. Methods of determining propoxyphene are discussed.
Purification and analysis of the purity of NADH.
Authors: Margolis S A , Howell B F , Schaffer R 
Published: January 2020

Abstract
We developed an analytical reverse-phase high-performance liquid chromatographic procedure for rapid assessment of the purity of NADH. The method completely separates adenosine monophosphate and adenosine diphosphoribose from NADH. By use of this analytical technique we found that preparative chromatography on DEAE-cellulose gives NADH that is free from adenine nucleotides as well as other impurities that commonly are present in NADH. The absorbance ratio at 260 and 340 nm of the purified NADH in 1.8 mmol/liter ammonium carbonate is 2.261 +/- 0.002 (+/- 1 SD).
Measuring water content of feces by the Karl Fischer method.
Authors: Jensen R , Buffangeix D , Covi G 
Published: January 2020

Abstract
We describe a technique for measuring the water content of stools by the Karl Fischer method. The analysis is based on removal of water into a mixture of methanol/chloroform (1/2), after dispersion of the stool by sonication in presence of solvent. An aliquot of the solution thus obtained is placed in themeasuring cell of a Karl Fischer apparatus and then analyzed in the classic way. We further describe the advantages of this method (odorless, precise, reproducible) in contrast to other current methods. In addition the same organic solution can also be used in determining the lipid content of stools.
Factors influencing results for thyroxine concentration in blood, as measured in paper filter spots in a screening program for neonatal hypothyroidism.
Authors: Dussault J H , Morissette J , Fiset P , Laberge E , Laberge C 
Published: January 2020

Abstract
To reduce the number of false-positives in our screening program for neonatal hypothyroidism, we investigated the effect of age, body weight, and interval between sampling and analysis on results for filter paper spot thyroxine determination. The statistical analysis included an analysis of covariance. The age of the infant did not influence the results, the interval influenced them minimally, but weight did require a correction factor of about 0.16 ng/kg below the mean weight. This correction factor should reduce our false-positives from 0.75% to 0.60%. Furthermore, because all hypothyroid infants had results that fell more than 2.8 SD below the geometric mean, we intend to measure thyrotropin concentrations in the blood eluate of all the spots with a thyroxine concentration below that cut-off point.
An immobilized-enzyme flow-enthalpimetric analyzer: application to glucose determination by direct phosphorylation catalyzed by hexokinase.
Authors: Bowers L D , Carr P W 
Published: January 2020

Abstract
A novel flow-enthalpimetric analyzer is described and its use demonstrated by an analysis in which glucose is determined by its hexokinase-catalyzed phosphorylation reaction. The method depends on measurement of the temperature differential across a column packed with glass-supported immoblized enzyme. Sample volumes of 120 mul can be used to obtain a calibration curve that is linear up to 25 mmol of glucose per liter. A precision (within-day) of 5% is generally observed in the optimum concentration range where glucose is quantitatively phosphorylated. Results by the technique correlate reasonably with those by the o-toluidine and the hexokinase/glucose-6-phosphate dehydrogenase methods: Other sugars--including fructose, glucosamine, and mannose--will interfere; galactose does not. The technique is amenable to both routine and emergency analyses.