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Biomedical subjects

P Fong

Publications and source records attributed to P Fong.

26 records · Page 2Linked to original sources
PubMed1986

Performance of solid-state 48 detector gamma counter using solid phase total thyroxin and free thyroxin assays.

We evaluated the performance of an automated 48 detector KinetiCount gamma counter using solid phase reagents for total thyroxin (TT4) and free thyroxin (FT4). Interassay coefficients of variations (CV) for both total T4 and free T4 ranged from 5.4% to 13%. Between-method correlation coefficients were 0.9798 for TT4 and 0.8844 for FT4. Detection limits for TT4 and FT4 were 3 micrograms/l and 3 ng/l, respectively. TT4 was linear up to 200 micrograms/l. The recovery of TT4 was between 99 to 101%. A computer-stored standard curve for total T4 was stable over a 6-day period. The 48 counting chambers demonstrated stability over a 45-day period with no significant changes in counting efficiency (p greater than 0.5). Precision between the 48 chambers gave a CV of 1.6%. Crosstalk between chambers was less than 0.3% with count rates up to 80,000 cpm. We conclude that the KinetiCount immunoassay system using solid phase separation technology performs well and is suitable for routine clinical use.

Evaluation Studies as Topic↗
PubMedDate not supplied

Midgestational exposure of pregnant BALB/c mice to magnetic resonance imaging conditions.

The potential for producing reproductive toxicity or teratogenesis in mice by exposure to magnetic resonance imaging (MRI) conditions was evaluated by means of reproduction studies and the homeotic shift test. Embryos from pregnant BALB/c mice were exposed in vivo for 16 hours beginning on gestation day 8.75 to MRI conditions of modest field strength (static field, 0.35 tesla (T); pulsed gradients, 2.3 X 10(-4) T/cm for 2.5 to 10 msec; and radio frequency, 15 MHz at an average of 61.2 mW). Unexposed, sham-exposed (both MRI and X-ray) and X-irradiated (0.5 Gy) animals were the control groups. Neither placental resorptions nor stillbirths were increased by MRI. Fetal weight at birth and crown-rump length were proportional; however, crown-rump length was significantly less (p less than 0.001) in the MRI-exposed fetuses (respective mean values for MRI-exposed fetuses were 21.8 +/- 0.2 mm compared to 22.4 +/- 0.1 for sham-exposed fetuses). Both crown-rump length and fetal weight were significantly reduced after X-irradiation. The percentage of homeotic skeletal shifts was scored for each of eight anatomic sites. Only X-radiation produced significant increases in skeletal shifts. Prolonged midgestational exposure of mice to MRI conditions currently used for human clinical imaging, therefore, failed to reveal overt embryotoxicity (resorptions, stillbirths) or teratogenicity (homeotic shifts), consistent with the non-ionizing properties of MR. However, the slight but significant reduction in fetal crown-rump length after prolonged exposure justifies further study of higher MRI energy levels and consideration of other endpoints for establishing with greater confidence the safety of MRI during pregnancy.

Animals↗