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Biomedical subjects

K Tran

Publications and source records attributed to K Tran.

60 records · Page 4Linked to original sources
PubMed1988

Effect of vitamin E enrichment on arachidonic acid release and cellular phospholipids in cultured human endothelial cells.

The effect of (R,R,R)-alpha-tocopherol on agonist-stimulated arachidonate release and cellular lipids was investigated in cultured human umbilical cord endothelial cells. Endothelial cells in culture incorporate added tocopherol in a dose-dependent manner at both physiological (23.2 microM) or pharmacological (92.8 microM) concentrations which were well tolerated by the cells, as judged by unaltered cell number and viability. Two experiments were conducted in which cells were either incubated with (R,R,R)-alpha-tocopherol followed by labelling with [1-14C]arachidonic acid or they were labelled with arachidonate followed by incubation with tocopherol. Irrespective of the sequence of incubation with arachidonate and tocopherol, (R,R,R)-alpha-tocopherol-enriched cells released significantly more labelled arachidonate when stimulated with thrombin (2.5 U/ml) or ionophore A23187 (1 microM) for 10 min. The magnitude of [1-14C]arachidonate release was higher from ionophore A23187 stimulation than from thrombin stimulation, but the trend of increased arachidonate release in tocopherol-enriched cells was the same. Results from these studies demonstrate that (R,R,R)-alpha-tocopherol can stimulate arachidonate release in human endothelial cells. This observation is in direct contrast to the role of tocopherol, which has been shown to inhibit platelet and cardiac phospholipase A2 activity in rats, and to reduce thrombin-stimulated thromboxane release in rat platelets.

Arachidonic Acid↗
PubMed1982

Tc-99m-labeled polystyrene and cellulose macromolecules: agents for gastrointestinal scintigraphy.

Several polystyrene resin and cellulose derivatives were evaluated for potential use as Tc-99m-labeled particulate markers for studies of gastric emptying and intestinal transit time, and for imaging segments of the gastrointestinal tract. The polyamine and quaternary ammonium polystyrene resins bound pertechnetate (Tc--99m) anions effectively; the labeling efficiency was over 95% at physiological pH values. In-vitro stability studies of Tc-99m-labeled resins in simulated gastric and intestinal fluid showed that less than 8% of the label was released after 24 h. The commercial resins dowex 2-XB, AG 1-X2, and Bio-Rex 9, labeled with Tc-99m, may be used as particulate markers of solid digesta in external scintigraphic studies of the gastrointestinal tract. Dowex 2-X8 showed relatively more extensive uptake of pertechnetate and greater stability in simulated gastric and intestinal fluids.

Cellulose↗
PubMedDate not supplied

Material properties of cobweb silk from the black widow spider Latrodectus hesperus.

We present the material analysis of scaffolding silk from the cobweb of the black widow spider Latrodectus hesperus. 30 strands were tested from the webs of nine spiders. Strands were stretched at 0.211 mm/s as force and extension were recorded. Cross-sectional area was measured under 1000 x oil-immersion light microscopy. The stress strain curve shows that cobweb silk is a distinct material from other known spider silks. The average breaking point for this cobweb silk is 1.1 +/- 0.5 GPa at 0.22 +/- 0.05 strain. All samples increased stiffness as they were stretched, but to different extents. Variation in stiffness might be due to differential crystallization or alignment of the silk proteins during stretching.

Animals↗
PubMedDate not supplied

Quantitation of residual white cells in filtered blood components by polymerase chain reaction amplification of HLA DQ-A DNA.

BACKGROUND: Over the past several years, blood filtration technology has improved dramatically, such that currently available experimental filters are capable of reducing white cells (WBCs) in blood components to less than 0.1 WBC per microL. These residual WBC concentrations are below the sensitivity of automated cell counters, as well as of large-volume (Nageotte) hemocytometers. STUDY DESIGN AND METHODS: A quantitative polymerase chain reaction (PCR) amplification assay directed at HLA DQ-A DNA sequences has been developed for the enumeration of WBCs in filtered blood. To ensure quantitative recovery of WBCs at very low residual cell concentrations, a direct red cell lysis and WBC concentration protocol using 0.5 mL of filtered blood was perfected. Amplified product is detected by oligomer hybridization using 32P-labeled probes, with quantitation by image analysis of autoradiographic signals relative to a standardized dilution series processed in parallel. RESULTS: Recovery of residual WBCs in filtrates was shown to be enhanced by the addition of xenogeneic WBCs or polystyrene beads, which served as "carrier" particles during red cell lysis and wash steps. A contribution of nuclear fragments in filtered blood to PCR signal in the range of 0.01 to 0.5 WBCs per microL was observed; a modified protocol was developed to minimize this effect. Parallel analysis of spiked dilution series and evaluations of 39 red cell components filtered through commercial filters indicated good correlation between PCR and standard Nageotte counts in the range of 0.1 to 10 WBCs per microL (r2 = 0.94); only PCR was able to detect residual WBCs in filtrates from prototype 6 log10 WBC-reduction filters. CONCLUSION: This assay should prove useful for the development and quality assurance of increasingly efficient WBC-reduction filters.

Blood Component Removal↗
PubMedDate not supplied

Ulnar artery aneurysm of the hand.

A case of traumatic ulnar artery aneurysm is presented in this study, and the relationship between the various forms of ulnar artery aneurysm and the different methods of treatment, as well as the arterial implications are discussed. The individual palmar arch anatomy may indicate and influence the choice of management technique, in each case.

Adult↗