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Biomedical subjects

J W Haines

Publications and source records attributed to J W Haines.

24 records · Page 2Linked to original sources
PubMed1983

Pattern of uptake of americium-241 by the rat skeleton and its subsequent redistribution and retention: implications for human dosimetry and toxicology.

The distribution and retention of intravenously injected 241Am in the skeleton of the female rat has been investigated using autoradiographic and radiochemical techniques. The studies were designed to assess the dosimetric and toxicologic implications of an 241Am intake by man. They showed that in the rat approximately one third of the intravenously injected 241Am was deposited in the skeleton where it appeared to be retained with a long biological half-time. The studies also showed: 1 241Am is initially deposited onto all types of bone surface including endosteal surfaces, periosteal surfaces and those of the vascular canals within cortical bone, but seems to be preferentially deposited onto those that are resorbing, 2 Bone accretion results in the burial of surface deposits of 241Am, 3 Bone resorption causes the removal of 241Am from surfaces, 4 Resorbed 241Am is retained by phagocytic cells (probably macrophages) in the bone marrow, 5 The transfer of 241Am from the phagocytic cells in the marrow to adjacent bone surfaces seems to occur, (local recycling). 6 The possibility that some of the 241Am removed from the bone surfaces enters the blood and is redeposited in bone, (systemic recycling) cannot be dismissed. These results show that 241Am deposition and redistribution in bone shares many characteristics with other 'bone surface-seeking radionuclides' typified by 239Pu. Consequently, it is suggested that a similar model to that used to calculate annual limits of intake for 239Pu in man would be suitable for the calculation of corresponding values for the 241Am isotopes.

Americium↗
PubMed1983

Autoradiographic studies of the distribution of radium-226 in rat bone: their implications for human radiation dosimetry and toxicity.

A solution containing 226Ra chloride was injected into young female rats via the saphenous vein. Subsequently, the distribution and retention of the 226Ra in the skeleton was studied. The results show that: 226Ra is initially deposited in the rat femur as a volume deposit and is fairly evenly distributed throughout the bone matrix. Much of the 226Ra initially deposited in the skeleton is lost within a few days of its administration. During the first week 226Ra gradually accumulates at sites of bone deposition including accreting surfaces. Subsequent bone growth results in the burial of contaminated bone surfaces and Following bone resorption some of the 226Ra released from individual bones is recycled systemically so that all skeletal components tend towards a uniform 226Ra concentration per unit of bone mineral. Of the two models conventionally used for radiation dosimetry purposes, the results reported here for rats suggest that though neither is ideal, the volume distribution model is preferable to the surface model at all times after the uptake of radium by the skeleton.

Animals↗
PubMed1982

Cystic parathyroid gland hyperplasia--hyperparathyroidism presenting as a neck mass.

Hyperparathyroidism may occasionally present as a neck mass resulting from cystic change in a parathyroid adenoma. We report an unusual instance of hyperparathyroidism presenting as a palpable, but asymptomatic hyperplastic parathyroid gland cyst. We conclude that hyperplastic parathyroid glands may undergo cystic degeneration resulting in a palpable neck mass; and that all functional parathyroid gland cysts are not necessarily adenomas. Therefore, during parathyroidectomy procedures, biopsy material from at least one additional parathyroid gland should be obtained.

Aged↗
PubMed1982

The release of plutonium from macrophages in rats: the effect of changes in iron status.

Female rats were used to study the loss of plutonium from hepatic and splenic macrophages. The plutonium was administered intravenously either as a "soluble" [Pu] ferric hydroxide colloid or as an "insoluble" plutonium dioxide suspension. The "soluble" plutonium was lost much more rapidly from the liver than the "insoluble" plutonium. If the iron status of the rats was altered, shortly after the injection of the [Pu] ferric hydroxide colloid, either by the removal of blood or by the injection of colloidal iron, the rate of plutonium loss from the liver was changed. The plutonium was retained longer in those animals with excess storage iron than in those with depleted circulatory iron. These results are taken to indicate that iron and plutonium share common pathways of metabolism in macrophages.

Animals↗
PubMed1982

Uranium in bone: metabolic and autoradiographic studies in the rat.

The distribution and retention of intravenously injected hexavalent uranium-233 in the skeleton of the female rat has been investigated using a variety of autoradiographic and radiochemical techniques. These showed that approximately one third of the injected uranium is deposited in the skeleton where it is retained with an initial biological half-time of approximately 40 days. The studies also showed that: 1 Uranium is initially deposited onto all types of bone surface, but preferentially onto those that are accreting. 2 Uranium is deposited in the calcifying zones of skeletal cartilage. 3 Bone accretion results in the burial of surface deposits of uranium. 4 Bone resorption causes the removal of uranium from surfaces. 5 Resorbed uranium is not retained by osteoclasts and macrophages in the bone marrow. 6 Uranium removed from bone surfaces enters the bloodstream where most is either redeposited in bone or excreted via the kidneys. 7 The recycling of resorbed uranium within the skeleton tends to produce a uniform level of uranium contamination throughout mineralized bone. These results are taken to indicate that uranium deposition in bone shares characteristics in common with both the 'volume-seeking radionuclides' typified by the alkaline earth elements and with the 'bone surface-seeking radionuclides' typified by plutonium.

Animals↗