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Biomedical subjects

K C Kuo

Publications and source records attributed to K C Kuo.

At least 55 records · Page 3Linked to original sources
PubMed1979

Major and modified nucleosides in tRNA hydrolysates by high-performance liquid chromatography.

We describe a high-performance liquid chromatographic analytical method that can be readily placed in operation, and which is particularly well suited to scientists investigating tRNA structure, biosynthesis, and function, and for the determination of major and modified nucleosides of tRNA. The method is characterized by the following features: (1) Sensitivity at the nanogram level; (2) High chromatographic resolution and selectivity; (3) Direct measurement of nucleosides with accuracy and precision; (4) Analysis is non-destructive and the high capacity of this chromatographic system allows easy isolation of pure nucleosides for further characterization; (5) Rapid separation and measurement in ca. 1 h after hydrolysis to nucleosides; and (6) Quantitation without use of radiolabeled compounds; however, labeled compounds are readily isolated and measured.

Chemical Phenomena↗
PubMed1979

Quantitative gas-liquid chromatography of neutral sugars in human serum glycoproteins. Fucose, mannose, and galactose as predictors in ovarian and small cell lung carcinoma.

A precise and accurate gas-liquid chromatographic (GLC) method has been developed for the quantitative analysis of the neutral sugars L-fucose (6-deoxygalactose), mannose, galactose, and glucose in ethanol precipitates of human serum proteins. The chromatographic conditions and sample preparation resulted in short analysis time (20 min per run) and made routine analyses practicable (twelve samples per day). The alditol acetate derivatization yielded single derivatives for each sugar. Complete separation was achieved on a 2.0 m X 2 mm I.D. column with 2.0% Silar-7CP on Chromosorb W AW 80--100 mesh. The results of hydrolysis showed that the release of fucose and galactose preceded the release of mannose. Hydrolysis with AG 50 W-X8 (H+) ion-exchange resin in 0.5 N HCl at 100 degrees for 7 h optimized glycosidic bond cleavage with only minimal destruction of fucose, mannose and galactose. A combination of strong cation- and anion-exchange resin columns was used to remove chromatographic background of peptides, amino acids, amino sugars, and inorganic ions. An average R.S.D. of less than 4% with recovery of greater than 86% for the three sugars was achieved. The homogeneity of the chromatographic peaks for the neutral sugars of normal human serum glycoproteins was confirmed by GLC--mass spectrometry. Significantly elevated ratios of fucose, galactose, and mannose to serum protein were observed for patients with small cell lung and ovarian carcinomas.

Carcinoma↗
PubMed1979

High-performance liquid chromatographic analysis of biogenic amines in biological materials as o-phthalaldehyde derivatives.

A remarkably sensitive, simple and selective reversed-phase high-performance liquid chromatographic (HPLC) method has been developed, allowing, for the first time, the direct measurement of histamine, norepinephrine, octopamine, normetanephrine, dopamine, serotonin and tyramine in a single sample of plasma (2 ml), tissue (0.2 g), or urine. The biogenic amines were modified by pre-column derivatization with o-phthalaldehyde which stabilizes the molecules, aids in extraction, and improves HPLC detection at the nanogram level. To minimize losses during the sampling procedure a careful collection procedure was designed. We developed a simple sample cleanup in which the samples were thawed, neutralized with KOH, immediately derivatized, extracted into ethyl acetate (EtOAc) and then chromatographed by HPLC. The derivatives were stable in EtOAc for more then 24 h. Interfering amino acids were removed from the EtOAc by partitioning twice with Na2HPO4 buffer (pH 10.0). Complete separation was achieved in ca. 60--90 min on a muBondapak phenyl column using a stepwise gradient of acetonitrile and/or methanol-phosphate buffer (pH 5.1). A variable wavelength fluorometer with a 5-microliter flow-cell was used (excitation 340 nm; emission 480 nm). Linearity ranged from 200 pg to 50 ng onto the column. Precision (R.S.D.) for retention times was 1% and for derivatization and injection 2.5%. Recoveries of the seven biogenic amines from plasma spiked with 25 ng/ml averaged 70%, with a relative standard deviation of 6%. Separation studies were also done using a muBondapak C18 column. The effects of various eluents are presented. Gas-liquid chromatography was also investigated but lacked the sensitivity achieved by HPLC. The HPLC method is used routinely for the determination of biogenic amines in plasma from pigs with malignant hyperthemia and thermally stressed bovine. Significant differences in levels of biogenic amines were noted between stressed and non-stressed animals. Data on rat brain tissue samples were compared with the trihydroxyindole method and canine heart tissue was analyzed for ventricular norepinephrine and dopamine. Application of the method to urine from normal persons and a patient with a brain tumor has been demonstrated.

Animals↗
PubMed1979

Interaction of factors associated with cancer of the nasopharynx.

A retrospective study of nasopharyngeal carcinoma (NPC) revealed that smoking, working under poor ventilation, use of nasal balms or oil for nasal and throat troubles, use of herbal drugs, and anti-EBV antibody titer were found statistically associated. The dural interactions of these factors to the risk of NPC were presented. Except in work conditions with poor ventilation and when herbal drugs are used, all the combinations were synergistic. The synergistic actions were especially remarkable with smoking and other factors. The possible etiological mechanisms of NPC are discussed.

Antibodies, Viral↗
PubMed1979

tRNA breakdown products as markers for cancer.

Seven breakdown products of tRNA were quantitated by high pressure liquid chromatography in urine and were related to the creatinine content. In the urine of 26 of 27 patients with 13 different malignancies, there was an elevation of one or more of these "markers." The levels of excretion vary approximately with the stage of the disease.

Aminoisobutyric Acids↗
PubMed1979

Patterns of urinary excretion of modified nucleosides.

A recently developed high-performance liquid chromatography method permits quantitative measurement of low levels of modified nucleosides in urine. We report on the patterns of excretion of seven modified nucleosides by normal subjects and cancer patients. It was found that the excretion of these nucleosides expressed as a function of creatinine concentration was constant, not episodic nor related to diet. Thus, randomly collected samples of urine are satisfactory sources for measurement of nucleosides, and the level of nucleosides is of significance when related to creatinine excretion. The constancy of the excretion of the modified nucleosides in normal subjects is quite remarkable. It implies strict metabolic control of transfer RNA turnover. The values for the individual nucleoside/creatinine ratios were found to be significantly elevated in the urine of colon cancer patients.

Adult↗
PubMed1978

Quantitative high-performance liquid chromatography of nucleosides in biological materials.

A rigorous, comprehensive, and reliable reversed-phase high-performance liquid chromatographic (HPLC) method has been developed for the analysis of ribonucleosides in urine (psi, m1A, m1I, m2G, A, m2(2)G). An initial isolation of ribonucleosides with an affinity gel containing an immobilized phenylboronic acid was used to improve selectivity and sensitivity. Response for all nucleosides was linear from 0.1 to 50 nmoles injected and good quantitation was obtained for 25 microliter or less of sample placed on the HPLC column. Excellent precision of analysis for urinary nucleosides was achieved on matrix dependent and independent samples, and the high resolution of the reversed-phase column allowed the complete separation of 9 nucleosides from other unidentified UV absorbing components at the 1-ng level. Supporting experimental data are presented on precision, recovery, chromatographic methods, minimum detection limit, retention time, relative molar response, sample clean-up, stability of nucleosides, boronate gel capacity, and application to analysis of urine from patients with leukemia and breast cancer. This method is now being used routinely for the determination of the concentration and ratios of nucleosides in urine from patients with different types of cancer and in chemotherapy response studies.

Boron Compounds↗
PubMed1978

Biologic markers in breast carcinoma. IV. Serum fucose-protein ratio. Comparisons with carcinoembryonic antigen and human chorionic gonadotrophin.

Serum fucose-protein ratio was evaluated as a potential biologic marker for patients with metastatic breast cancer. By analysis of the same blood samples, comparisons were made with carcinoembryonic antigen (CEA) and human chorionic gonadotrophin (hCG). For 150 patients with metastatic breast cancer, 85% had a value for serum-fucose protein ratio above the normal range in comparison to 75% for CEA and 40% for hCG. Serum fucose-protein ratio was exclusively increased in 12% of the patients, CEA in 4% and hCG in 2%. Both serum-fucose protein ratio and CEA were elevated in 39% of the patients, and together, either in combination of alone, were increased in 93% of the patients. Raised values for serum fucose-protein ratio as well as for CEA decreased with change in disease status from pretreatment to response for patients with measurable disease parameters and increased correspondingly with overt disease progression. Preliminary data indicate both serum fuxose-protein ratio and CEA frequently become elevated when patients progress from a disease free interval after surgery to recurrence.

Breast Neoplasms↗
PubMed1978

High-performance liquid-chromatographic separation and fluorescence measurement of biogenic amines in plasma, urine, and tissue.

We describe a high-performance liquid-chromatographic method for measuring histamine, norepinephrine, octopamine, normetanephrine, dopamine, serotonin, and tyramine in plasma (2 ml), brain (0.2 g), or urine. These amines are modifed by pre-column derivatization with o-phthalaldehyde, which stabilizes the molecules, facilitates extraction, and improves detection of nanogram amounts. Before separation, samples were neutralized with KOH and immediately derivatized and extracted into ethyl acetate, in which derivatives were stable for longer than 24 h. Interfering amino acids were removed from ethyl acetate by partitioning twice with Na2HPO4 buffer (pH 10.0). Separation was complete in about 90 min on a ""mu Bondapak/phenyl" column, with which a stepwise gradient of methanol/phosphate buffer (pH 5.1) was used. A variable-wavelength fluorometer was used (exciting wavelength, 340 nm; emission wavelength, 480 nm). Amount and response were linearly related from 1 to 200 pmol. Precision (CV) for retention times was 1%, for derivatization and injection 2.5%. Analytical recoveries of the seven amines from 2 ml of plasma fortified with 200 pmol averaged 65% (CV approximately 8%). Data on rat-brain tissue samples are compared with results by the trihydroxyindole method. Application of the method to urine from normal persons and a patient with a brain tumor is demonstrated.

Biogenic Amines↗
PubMed1978

Dual-column cation-exchange chromatographic method for beta-aminoisobutyric acid and beta-alanine in biological samples.

A rapid, automated chromatographic method has been developed for the quantitation of the nucleic acid catabolites beta-aminoisobutyric acid and beta-alanine in urine, serum, and other physiological fluids. The analyses were performed on a modified Beckman 121M amino acid analyzer with dual ion-exchange columns and the use of a single sodium citrate buffer (pH 4.38, 0.20 mol/liter). By carefully matching the elution pattern for the two ion-exchange columns and alternating use of these columns, analyses are completed every 40 min. The chromatography, regeneration, and equilibration of the two columns are precisely programmed, thus the detector sees only the elution of beta-aminoisobutyric acid and beta-alanine alternately from each column. Long-term precision and analytical recovery for the two metabolites in urine were 1.9 and 102%, and 3.3 and 101%, respectively. Their normal physiological values were determined in human serum and urine. Their excretion in the urine was also studied as a function of collection time, to validate a more convenient, less costly method of sampling. This study shows that randomly collected samples are acceptable when the concentration of the two metabolites are expressed in terms of creatinine excretion. In addition, the distribution of the free and conjugated forms of the two metabolites in urine and serum was studied. A preparative method was also developed for the quantitative isolation of beta-amino-isobutyric acid from urine samples. The alternating dual-column technique may be applied to any ion-exchange chromatographic method where many analyses must be performed. This method is currently used in our laboratories for measuring these beta-amino acids in urine and serum of patients with various types of cancers.

Alanine↗
PubMed1976

Beta-aminoaciduria in patients with Burkitt's lymphoma.

The massive amounts of beta-aminoisobutyric acid (beta-AIBA) in the urine of Burkitt's lymphoma patients were measured along with other alpha-amino acids and beta-alanine present in normal and decreased levels. The ratios of the amount of beta-AIBA to beta-alanine, in mumoles/kg urine collected in 24 hours, were elevated for all patients. The degree of elevation of beta-AIBA excretion and the ratio of the two beta-amino acids appeared to be related to the amount of tumor mass present. These analyses may have possible value in monitoring patients with Burkitt's lymphoma during their disease course.

Alanine↗
PubMedDate not supplied

Potential biologic markers in Burkitt's lymphoma.

Specific biochemical molecules used as potential biologic markers, including modified nucleosides, polyamines, and pyrimidine catabolic end-products, were quantitatively measured in the urine of seven patients with Burkitt's lymphoma before, during, and after one or more courses of therapy. The results of this preliminary study demonstrated that patients with this disease frequently excrete significantly increased amounts oof modified nuceleosides (considered to be derived primarily from transfer ribonucleic acid), polyamines, and beta-aminoisobutyric acid during the course of their disease. With successful treatment and rapid destruction of tumor cells, a concomitant rise in these molecules occurs. Elevations were observed prior to chemotherapy and changes in levels associated with treatment or tumor progression appeared to correlate with disease status and to aid in assessing antitumor response. Periodic follow-up analysis of these molecules may be helfful in appraising relapse or recurrence of the malignancy prior to overt evidence of tumor by existing clincial means.

Adolescent↗