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Biomedical subjects

D J Pizzarello

Publications and source records attributed to D J Pizzarello.

At least 19 recordsLinked to original sources
PubMed1995

Effect of magnetic resonance exposure combined with gadopentetate dimeglumine on chromosomes in animal specimens.

RATIONALE AND OBJECTIVES: We tested for the presence of a form of unstable chromosomal damage--anaphase bridges--that might result from the combined exposure to gadopentetate dimeglumine and magnetic resonance (MR) imaging in rats. METHODS: Fifty-four male Sprague-Dawley rats, along with appropriate controls, were exposed either to MR imaging alone, gadopentetate dimeglumine alone, or a combination of the two. After exposure, partial hepatectomies were performed to induce a vigorous mitotic response in the regenerating liver stump. Twenty-eight to 30 hr after partial hepatectomy, tissue specimens from regenerating liver were removed and analyzed microscopically for the presence of anaphase bridges. RESULTS: No anaphase bridges were detected in any of the animals, including those exposed to gadopentetate dimeglumine and MR imaging. CONCLUSION: Using anaphase bridge formation as an indicator, exposure to MR imaging alone, gadopentetate dimeglumine alone, or a combination of the two under the conditions used in this experiment did not cause detectable unstable chromosomal damage.

Anaphase↗
PubMed1986

Effects of mitotic activity and water content on the proton relaxation times in partially hepatectomized and sham-operated rat livers.

Proton relaxation times, T1 and T2, water content, and mitotic activity in control, sham-operated and partially hepatectomized rat livers were measured before surgery, and at 28 hours, 48 hours and six days after surgery. T1, water content, and mitotic activity increased after partial hepatectomy, but T1 was also elevated after sham operations, whereas neither water content nor mitotic activity changed. T2 was unaffected by either procedure. The T1 changed is more likely to be the result of surgery related stress than of changes in water content or growth rate.

Animals↗
PubMed1986

The effect of stress on proton relaxation times (T1 and T2) of rat liver.

T1 of the liver has been shown to lengthen after sham operation or partial hepatectomy, reaching a maximum about 24 hours after surgery. Surgical stress, which includes tissue injury and repair, has been suggested as the source of the change. We subjected rats to three types of stress that do not include tissue damage and repair to determine the role of stress alone in the length of T1 of the liver. Prolonged swimming, ACTH injection, or fasting did not affect T1 times. Tissue damage and/or repair appear to have a major role in determining T1 in the liver.

Adrenocorticotropic Hormone↗
PubMed1984

The carcinogenicity of radiation therapy.

Ionizing radiation as used for therapy for cancer is probably weakly carcinogenic at worst. The probability that cancers will be induced at a distance from the treatment volume is so small that it can only be inferred from experiences with large populations exposed to much higher radiation doses. The risk of cancer in and adjacent to the treatment volume also appears to be small, especially in adults. Intensive radiotherapy or radiotherapy of children 20 to 30 years ago appears to have induced secondary cancers in about 3 to 4 per cent of those treated, but modern practice has every expectation of reducing this incidence. No precise risk factor can be offered, but it seems likely that less than 3 to 4 per cent is a reasonable projection. The reason for the low carcinogenicity in the treatment volume probably lies in the fact that the irradiation dose is high and many cells are killed rather than transformed. The frequency of the induction of radiogenic cancer adjacent to or near the treatment volume is expected to vary according to the tissue exposed. It is not estimated to exceed a few per cent in the worst instances (for example, breast and thyroid gland) and is much less than 1 per cent in most tissues.

Adult↗
PubMed1976

Influence of dose rate on carcinogenesis resulting from x-ray, 113In, and 198Au irradiation.

The potential hazards from internally administered radionuclides used in nuclear medicine are usually compared with one another and with diagnostic x-rays on the basis of the absorbed dose in rads, with no regard to the dose rate of the radiation. This study compared the carcinogenic potential of a dose of 250 rads delivered at different dose rates to rat livers by x-ray, 113mIn, and 198Au. The chemical carcinogen N-2-fluorenyldiacetamide was administered after irradiation to reduce the latent period and increase the number of radiogenic liver tumors. No significant difference in tumor incidence was observed among groups of animals treated with either 198Au, 113mIn, or x-irradiation.

2-Acetylaminofluorene↗
PubMed1975

Biological detection of reduction in dose at the surface of volume sources containing beta emitters.

Dosimetry theory related to volume sources containing uniformly distributed beta-emitting radionuclides predicts a rapid drop in dose at the outer surface to approximately one half of the maximum dose within the volume. The purpose of this study was to determine if this reduction in surface dose could be observed using a measurable biological endpoint. In this study rats were injected with radiocolloids of either 198Au, 113In-m or 99Tc-m, to produce liver irradiation from their decay, or their livers were treated with external X-irradiation. After irradiation, a portion of the liver was surgically removed to stimulate cell division in the liver remnant revealing radiation damage in the form of chromosomal aberrations. The percentages of dividing cells with bridges were scored in the outer edges (0.45 mm) of the tissue sections and were compared to levels obtained from the central portion of the liver lobe. No significant difference was observed with X-irradiation or from 99Tc-m irradiation. However, irradiation with 198-Au and 113In-m (which emit large numbers of energetic electrons) produced significantly fewer aberrations in the outer layer when compared to the central portion. These differences in the distribution of biological damage allowed us to detect the predicted dose reduction at the surface of volume sources containing beta emitters.

Animals↗
PubMed1975

A new approach to testing the effect of ultrasound on tissue growth and differentiation.

Pulsed ultrasound from a Picker Ultrasonoscopy Model 102, with a frequency of 500 Hz and an energy of 2.2 MHz was applied to the amputated left forelimbs of 24 adult newts. Exposure time was 5 min in half of the animals and 10 min in the remainder. The right forelimbs of these newts were also amputated at the same time, at the same anatomical level, and by the same operator of the left forelimbs, but were not exposed to sonication. Regeneration of both forelimbs was compared and found to be generally slower in the ultrasonicated limb. In 75% there was a definite retardation of growth. The results suggest that the the growth of rapidly proliferating embryonic tissue (newt regenerates are formed from embryonic cells in the stump) is inhibited by ultrasonication.

Animals↗