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Biomedical subjects

J D Harrison

Publications and source records attributed to J D Harrison.

At least 127 records · Page 7Linked to original sources
PubMed1986

The gastrointestinal absorption of organically bound forms of plutonium in fed and fasted hamsters.

Values of about 0.005-0.01 per cent were obtained for the absorption in fed hamsters of plutonium ingested as Pu4+ citrate, isocitrate, phytate and malate complexes and Pu3+ ascorbate compared with about 0.003-0.004 per cent for Pu4+ nitrate. Replacing drinking water with tea did not affect the result for Pu4+ nitrate. Fasting hamsters for 8 h before the administration of plutonium citrate increased absorption to 0.1-0.2 per cent. An extra period of fasting for 4 h after administration did not lead to a further increase in absorption. Similar values were also obtained when plutonium citrate was administered after a 24 h fast, followed either by immediate access to food or a further 4 h fast. In hamsters fasted for 24 h before administration of either Pu3+ ascorbate or Pu4+ nitrate, about 6-7 per cent of the ingested plutonium was retained in the gastrointestinal tract after one week. At three weeks after ingestion of Pu3+ ascorbate, gastrointestinal retention had fallen 100-fold without an increase in absorption.

Animals↗
PubMed1986

Ultrastructural and histochemical observations on intracellular and luminal microcalculi in the feline sublingual salivary gland.

As the genesis of salivary calculi in man has not been established, the fortuitous observation of microcalculi in sublingual glands of cats prompted this study. Microcalculi were seen occasionally within acinar cells and lumina and macrophages, and rarely interstitially. Microcalculi were stained with the periodic-acid/Schiff technique, and acid-phosphatase activity was associated with intracellular microcalculi. Intracellular microcalculi were seen ultrastructurally in acinar cells in membrane-bound vacuoles that also contained debris and sometimes what appeared to be secretory material. X-ray microanalysis showed the microcalculi to consist of crystals containing calcium and phosphorus. The observations suggest that the microcalculi form within autophagosomes in acinar cells by a precipitation of calcium and phosphorus present in degenerate material, and that the microcalculi eventually enter lumina, where they may be discharged in the saliva or retained and enlarge.

Animals↗
PubMed1986

Oral vegetable granuloma: ultrastructural and histological study.

An unusual giant-cell granulomatous inflammatory oral lesion is characterised by the presence of hyaline rings and by a lack of agreement on their nature, opinions ranging from their being hyaline degenerative blood-vessels to remains of leguminous cells. Ten such lesions and a variety of vegetables have been examined in the present investigation. Light-microscopical examination of the lesions revealed the hyaline rings surrounded by inflamed granulation tissue with associated multinuclear giant cells. Electron-microscopical examination showed them to consist of a material similar to that of vegetable cell walls, sometimes with an associated superficial layer of collagen. The observations indicate that the lesions consist of vegetable remains with an associated foreign-body type of inflammatory response.

Adolescent↗
PubMed1985

Myxoid meningioma: histochemistry and electron microscopy.

Two meningiomas were investigated that consisted largely of myxoid tissue. Staining with Alcian blue and incubation with staphylococcal, Streptomyces or testicular hyaluronidase revealed that the matrix of the myxoid tissue contained hyaluronic acid and chondroitin sulphate. Special fixation was used for ultrastructural preservation of the myxoid matrix, and its ultrastructural appearance was that of these glycosaminoglycans. The previous appellations of microcystic or vacuolated meningioma applied to this type of meningioma relate apparently to poor preservation of myxoid tissue.

Adult↗
PubMed1985

Pancreatic injury in association football.

A case is presented of isolated pancreatic transection sustained in the course of a game of Association Football. The difficulty of early diagnosis is discussed. Emphasis is laid on the importance of possible pancreatic injury in the normotensive patient and on inspecting the posterior abdominal structures on opening the lesser sac during laparotomy.

Adolescent↗
PubMed1984

The speciation of plutonium in foodstuffs and its influence on gut uptake.

Soluble plutonium complexing agents in foodstuffs have been identified. These have been labelled to high specific activity with 238Pu and their gut uptake determined in rats. The range of values found for naturally-occurring complexes was between 0.03% for oxalate and 0.1% for phytate. However, reasons are advanced for believing that the enhancement of uptake in rats fed the phytate complex would not be expected to occur in man. These results are not taken, therefore, as suggesting that there should be any change in the gut uptake factor of 0.05% currently recommended by the National Radiological Protection Board for plutonium contained in foodstuffs eaten by humans.

6-Phytase↗
PubMed1984

The effect of concentration and chemical form on the gastrointestinal absorption of neptunium.

The gastrointestinal absorption of neptunium at low mass concentrations as 239Np nitrate (0.5-1 ng Np; 2-5 micrograms l-1) has been found to be 0.03, 0.02 and 0.18 per cent in adult rats, hamsters and rabbits, respectively. Administration as 239Np bicarbonate increased uptake in the rat to 0.15 per cent but had no significant effect on uptake in either the hamster or the rabbit. Absorption in the rat was also increased to 0.14 per cent for 239Np citrate but not for either 239Np phytate (0.04 per cent) or 239Np incorporated into rat liver (0.01 per cent). The fasting of rats for 8 hours increased their subsequent absorption of 239Np as the bicarbonate to 0.25 per cent. The absorption of neptunium at high mass concentrations as 237Np nitrate (0.5 mg Np, 5 g l-1) was increased to 0.26 per cent in the rat compared with the value of 0.03 per cent for 239Np (0.5 ng, 5 micrograms l-1) but a similar effect of concentration was not observed in the hamster. The results support the use of a value of absorption of 0.1 per cent instead of 1 per cent in calculations of annual limits on intake of radioisotopes of neptunium by workers and in estimates of radiation doses resulting from the ingestion of contaminated food and water by adult members of the public.

Animals↗
PubMed1984

The absorption of ingested neptunium, plutonium and americium in newborn hamsters.

Hamsters aged 1, 4, 7, 22 and 30 days were given oral doses of either plutonium-239 citrate or americium-241 nitrate. The values of gastrointestinal absorption obtained were 3.5, 1.4, 0.04, 0.007 and 0.003 per cent, respectively, for plutonium and 4.5, 1.7, 0.5, 0.006 and 0.02 per cent, respectively, for americium, compared with values in adults of 0.01 per cent for plutonium and 0.05 per cent for americium. The absorption of neptunium was measured in hamsters aged 2 and 4 days and values of 2.3 and 1.7 per cent, respectively, were obtained for 239Np as the nitrate and 5.5 and 2.1 per cent, respectively, for 239Np as the bicarbonate compared with the values in adults of 0.02 per cent for both chemical forms. Thus, the absorption of plutonium, americium and neptunium at 1-2 days of age was about 100 times greater than in adults. The results for plutonium and americium show that absorption decreased rapidly with age over the suckling period. The values of absorption obtained at the time of weaning at 22 days were lower than in adults.

Aging↗
PubMed1983

Tooth contact patterns and contractile activity of the elevator jaw muscles during mastication of two different types of food.

The pattern of molar and canine contacts and the contractile activity of the masseter and anterior temporal muscle were studied, through integrated electromyography, during right-sided mastication of banana and apple in ten healthy male subjects. Tooth contacts occurred on both the chewing and the non-chewing side. This study does not support the clinical concept that non-chewing side contacts are necessarily detrimental to the jaw muscles and the temporomandibular joints. The activity of the elevator jaw muscles and the tooth contact patterns suggest that the mandible tilted around a sagittal axis, and rotated around a vertical axis, during the phase of elevation of a masticatory cycle.

Adult↗
PubMed1982

Ultrastructural cytochemistry of phosphatases in the ductal component of pleomorphic adenoma of human parotid and submandibular salivary glands.

Some ductal cells of pleomorphic adenomas showed evidence of secretory activity, with apical secretory granules, thiamine pyrophosphatase activity in the Golgi apparatus, and acid phosphatase activity in GERL-like structures and in immature secretory granules. Alkaline phosphatase activity was demonstrated rarely at the luminal plasma membrane and in intracellular vesicles, suggesting resorptive activity. ATPase reaction product was associated with contiguous surfaces of tumour cells, particularly of those cells adjacent to the basement membrane, these latter cells apparently differentiating in a different manner to the luminal cells. A comparison of luminal ductal cells of the tumours with normal salivary glands revealed most similarity with intercalary ductal cells.

Adenoma, Pleomorphic↗
PubMed1982

Ultrastructural phosphatase cytochemistry of the intercalary ducts of the parotid and submandibular salivary glands of man.

Cells of the intercalary ducts showed concentrations of secretory granules adjacent to the luminal plasma membrane. Evidence of thiamine-pyrophosphatase activity was seen in the Golgi apparatus and of acid-phosphatase activity in GERL-like structure, lysosomes and immature secretory granules. Adenosine-triphosphatase reaction-product was present along surfaces of myoepithelial cells and to a lesser extent along contiguous surfaces of duct cells. The findings indicate secretory activity in the intercalary duct cells.

Cytoplasmic Granules↗
PubMed1982

Delayed onset of masseter muscle pain in experimental tooth clenching.

At 100% and about 50% of maximum voluntary isometric contraction strength of the masseter muscle, six healthy human subjects exercised tooth clenching until there was onset of muscle pain in 42 and 146 sec, respectively. Onset of pain, at maximum contraction strength, might have been due to the cumulative amount of activity in relatively large motor units. The delayed onset of pain might have been associated with a decline in the quantity and quality of contracting large motor units. The Clinical implications of this study suggest that an increase of the vertical dimension of the face will delay the onset of muscle pain in patients suffering from tooth clenching.

Adult↗