Chien Chung

Lipiodol uptake and retention by human hepatoma cells

Lipodol has important diagnostic and therapeutic uses in hepatoma. However, the mechanisms of its selective, prolonged retention in hepatoma cells is not well understood. Therefore, using oil-red O, light and electron microscopy and neutron activation analysis we have determined that HepG2 cells are characterized by lipiodol deposition and emulsification on the cell surface, action uptake of lipodol by endocytosis, and prolonged intracellular retention. These findings may have major clinical significance in the development of a new treatment for hepatoma patients.

Performance of a HPGe-NaI(Tl) Compton suppression spectrometer in high-level radioenvironmental studies

Abstract A Compton suppression spectrometer used for gamma-ray spectroscopy in high level radioenvironmental studies is described. A 113 cm 3 intrinsic germanium detector is inserted into a 22.9×25.4 cm annular NaI(Tl) detector and coupled to an anticoincidence gating system. The performance of suppression of the Compton continuum is studied as a function of various source-to-detector distances, incident gamma-ray energies, as well as the intensity of activities. The optimum suppression factor is 5.2 at a photon energy of 662 keV. Examples are given for use at medium and high level radioenvironmental measurements on the nuclear reactor experimental floor before and during reactor operation. Characteristics of this spectrometer are compared with other representative systems and special features are discussed.

Daily dietary intake of minor and trace elements by upper social groups in Taiwan

Sixteen minor and trace element contents of diet samples from three different social population groups in Taiwan were determined. Samples were prepared using duplicate portion technique by collecting the 15 subjects ate and drank during a 3-day period. Samples were homogenized, freeze-dried, and elemental concentration of minor and trace elements were determined by instrumental neutron activation analysis. Elemental concentrations and daily dietary intake of the elements were compared with those in the other nations, and possible origins were discussed.

Direct determination of selenium in serum by electrothermal atomic absorption spectrometry using automated ultrasonic slurry sampling

Abstract Selenium concentration in body fluids is a good index to establish human selenium status. This work discusses the determination of selenium in serum by ETAAS using longitudinal Zeeman-effect background correction and combining the use of automated slurry sampling. The standard reference materials bovine serum (NIST, SRM 1598) and second-generation biological freeze-dried human serum are analyzed to verify the accuracy and precision of this technique. The direct method proposed in this study is used for the determination of selenium in human serum collected from healthy people of 19–25 years. The average accuracy values of certified reference serum samples and the recovery values of spiked samples indicate this method to be an efficient and rapid technique for determining selenium in biological samples.

A feasibility study of the In vivo prompt gamma activation analysis using a mobile nuclear reactor

A facility for in vivo prompt gamma activation analysis using moderated neutron beams from a 0.1 W mobile nuclear reactor is described. The low-power nuclear reactor provides total neutron flux of 3.3 X 10(4)n cm-2 s-1 on the surface of a vertical beam tube to which a liquid phantom is positioned. The capability of such a partial-body irradiation facility is demonstrated by measuring trace amounts of toxic cadmium in kidney. The detection limit of Cd in kidney for a skin dose of 1.66 mSv (166 mrem) is 1.34 mg under 500 s irradiation. This facility therefore combines the advantages of mobility with high sensitivity of detection of a toxic element under low neutron and gamma doses.

In situ prompt gamma-ray activation analysis of water pollutants using a shallow 252Cf-HPGe probe

A shallow 252Cf-HPGe probe used for in situ prompt γ-ray activation of water pollutants is described. A 2.7 μg 252Cf neutron source and a 10% HPGe detector are inserted into a waterproof stainless steel probe, which is designed to be submerged and recovered in field operation. A laboratory test is performed to obtain the neutron flux distribution and prompt γ-ray contribution to the HPGe detector counts from around the submerged probe. The concentrations of toxic cadmium and chlorine in water are determined in the prompt γ-ray spectrum. The detection limit of industrial pollutants and some improvements of the current design are discussed.

Preconcentration of Trace Elements from Natural Water for Analysis by Neutron Activation

The coprecipitation of trace elements from natural water samples by Pb and Bi salts of pyrrolidine dithiocarbamate or Bi salts with oxine and thionalide was studied with radiotracers. The concentration of the trace elements in samples of sea water was studied by coprecipitation followed by neutron activation analysis.

Tissue potassium, selenium, and iron levels associated with gastric cancer progression

The contents of 10 minor and trace elements in histologically confirmed gastric adenocarcinomas and their corresponding normal gastric mucosal tissues obtained from 39 patients at the time of gastric resection were simultaneously determined by instrumental neutron activation analysis. Specimens were irradiated by reactor neutrons and subsequently subject to direct analysis using a high-resolution HPGe γ-spectrometer. Univariate analysis revealed that gastric cancer tissues had significantly higher concentrations of Fe, K, Mg, Na, Rb, Se, and Zn than normal gastric mucosal tissues. However, multivariate analysis found that Fe, K, and Se were independent elements that associated with gastric cancer. Upon further evaluation of their clinical significance, we found a high tissue K level was related to lymphatic duct metastasis. High Se tissue levels were linked to intestinal type adenocarcinoma. A positive correlation was found between high Fe levels and vascular involvement. These findings suggest that Fe and K are associated with gastric cancer progression. Se is involved in carcinogenesis of stomach in high-risk areas. The mechanisms that underlie the corresponding pathohistological features deserve further study.

Environmental radioactivity and dose evaluation in Taiwan after the Chernobyl accident

A substantial increase in fission product activity was observed in various environmental samples taken in Taiwan after the Chernobyl accident. The concentration of long-lived fission products in air above ground, precipitation, grass, vegetation and milk were monitored in the next 7 wk. The individual effective dose equivalent committed by the first year of exposure and intake following the accident were evaluated. Average individual doses for the population in Taiwan are estimated at 0.9 microSv due to global fallout from the Chernobyl accident. This value is lower than that reported in neighboring countries in the Far East and poses no increased health impact to the public in Taiwan.

Trace elements in Taiwanese diet in different seasons

The trace element contents of Taiwanese diet were determined using conventional neutron activation analysis. Sample were prepared with duplicate portion technique by collecting food items ate and drank during a 3 day period in winter. Samples were homogenized, freeze-dried, and elemental concentration of trace elements were determined by instrumental neutron activation analysis. The interference from fast neutron induced reactions were corrected. Concentrations and daily dietary intake of the elements were compared with those collected in the summer, resulting less daily intake of K, Ca, Mn, Fe, and Zn among Taiwanese than the values recommended by WHO and RDA. Alarming low intake of Fe for females and Zn among Taiwanese were indicated.