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Biomedical subjects

B Tan

Publications and source records attributed to B Tan.

66 records · Page 4Linked to original sources
PubMed1991

Comparison of two locus of control scales in predicting relapse in an alcoholic population.

A 3-mo. follow-up was made of 64 male veterans who were discharged from a 21-day Alcohol Detoxification Treatment Program at the Veterans Affairs Medical Center at Lyons, NJ. Scores on the Rotter I-E and Alcohol Responsibility Scales were significantly correlated with tendencies toward a more external direction among the 13% who relapsed, significant on the I-E scale and nonsignificant on the Alcohol Responsibility Scale. When tests were compared as possible predictor variables of alcoholic relapse, the difference in favor of the I-E scale was statistically nonsignificant.

Adult↗
PubMed1989

Separation of tocopherol and tocotrienol isomers using normal- and reverse-phase liquid chromatography.

This optimization study for tocopherols and tocotrienols involved both normal- and reverse-phase liquid chromatography using various columns and mobile phases. Normal-phase systems showed elution of the homologs in order of increasing polarity with separation based on methyl substituents on the chromanol moiety. Reverse-phase systems showed class separation based on the saturation of the phytyl side chain; the more saturated tocopherols were retained on the column longer. When the Zorbax ODS was used with an isocratic ternary acetonitrile:methanol:methylene chloride (60:35:5) mixture, the optimized resolution was greater than 2.0 and separation was achieved in less than 13 min, but there was no separation of beta- and gamma-tocopherols. The normal-phase silica and amino columns provided separation of all available isomers with resolution greater than 1.1 and separation times of less than 5.5 and less than 10 min, respectively. Optimized isocratic binary solvent mixtures of hexane:2-propanol were used for silica (99:1) and amino (98:2) columns. Derivative spectra showed differences depending on substituents in the chromanol moiety but not the phytyl side chain. Second- and fourth-derivative spectra gave the best differentiation of the vitamin E isomers.

Chromatography, Liquid↗
PubMed1988

Analysis of palm oil carotenoids by HPLC with diode-array detection.

Palm oil carotenoids are analyzed by nonaqueous reversed-phase high-performance liquid chromatography (NARP-HPLC) with UV/vis diode-array detection. Isocratic elution with 60% acetonitrile/35% methanol/5% methylene chloride at 2 mL/min on a 25-cm C18 column results in an analysis time of 30 min. Identification is made through absorption spectra and chromatographic elution behaviors, for example, polyenic pi conjugation, dipole moment of end-groups, and oxygen function on the chromophores. At least 12 carotenoids are identified with alpha- and beta-carotene as the dominant carotenoids (1:2 ratio). Several mono- and di-epoxides of alpha- and beta-isomers and hydrocarbon carotenes are found, including the UV-absorbing phytoene identified by spectral substraction. cis-Isomerization is found and discussed in the light of spectral evidence. The effect of saponification time on the amount of extracted carotenes is investigated. Quantitation results in a combined alpha- and beta-carotene concentration of at least 506 ppm. The detection limit for beta-carotene is 31 ng.

Carotenoids↗
PubMed1986

A surface molecule on guinea pig lymphocytes involved in adhesion and homing.

A monoclonal antibody, CT 4, which recognizes an antigenic determinant on the majority of guinea pig lymphocytes, was tested for its ability to interfere with adherence and homing capacity of lymphocytes. Incubation with F(ab')2 fragments of the antibody blocks the in vitro binding to high endothelial venules (HEV) of both peripheral lymph nodes and Peyer's patches. When tested in vivo using a short-term homing assay with radiolabeled cells also a reduction of migration into the spleen was observed. Fluorescence-activated cell sorter analysis of lymph node cells showed a separation into duller and brightly positive cells whereas in the thymus the bright population is absent. Thymus cells adhere less effectively to HEV and this binding can only marginally be blocked by CT 4 incubation. The results suggest a role of CT 4 in adhesion processes.

Animals↗
PubMedDate not supplied

Effects of plant growth regulators on survival and recovery growth following cryopreservation.

Studies on the effects of plant growth regulators (PGRs) on survival, recovery and post-recovery growth of shoot apices following cryopreservation are limited. In this study, the effects of plant growth regulators in both the culture phase and the recovery phase of cryostorage were examined for the rare plant species, Anigozanthos viridis ssp terraspectans Hopper. Survival of shoot apices was not correlated to cytokinin or auxin treatments administered in culture media prior to cryostorage. In recovery media, the plant growth regulators, kinetin, zeatin (cytokinins), IAA, (auxin) and GA3 were examined for their effect following cryopreservation. It was found that the application of a combination of cytokinin and 0.5 microM GA3 from day zero was the most appropriate for obtaining vigorously growing plantlets following LN immersion. This combination proved to be more effective than basal medium, zeatin or kinetin treatments.

Cryopreservation↗
PubMedDate not supplied

Cryopreservation of the australian species Macropidia fuliginosa (Haemodoraceae) by vitrification.

Somatic embryos were used to develop a cryopreservation protocol for Macropidia fuliginosa, a commercially-important species endemic to the south-west of Western Australia. Somatic embryos were allowed to develop from embryogenic callus for three weeks on an kinetin medium prior to processing. These were transferred and cultured on a agar solidified basal medium supplemented with 0 to 0.6 M sorbitol for 2 d prior to incubation in Plant Vitrification Solution Two (PVS2). Following this, embryos were then washed in 1 M sucrose solution (treated controls) or cooled in liquid nitrogen (LN). Cooled embryos were then warmed and washed in sucrose solution. Highest survival for cooled treatments (67.3%) was achieved by preculture with 0.4 M sorbitol, then incubation in PVS2. Further experimentation varying pre-culture duration (2 or 3 d) and incubation on either glycerol (0.8 M) or sorbitol (0.4 M) indicated that very high survival (90.6%) of embryos was achievable by adopting a 2 d preculture period on 0.8 M glycerol. The phenotype and growth rates of plants obtained using this protocol were similar to those of parent plants. This optimised procedure was then applied to tissue culture-derived shoot apices of the same clone also resulting in a high survival rate (84.4%).

Journal Article↗
PubMedDate not supplied

Beta-zeacarotene of the bovine ovary.

An investigation of the carotenoids from a bovine ovary extract has revealed the presence of three Porter-Lincoln pathway intermediates of which beta-zeacarotene is previously unreported. Analysis using spectrophotometric and chemical tests reveals beta-zeacarotene (2.14 micrograms/g), alpha-carotene (0.11 microgram/g), and beta-carotene (27 and 35 micrograms/g).

Animals↗