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Biomedical subjects

C Allan

Publications and source records attributed to C Allan.

23 records · Page 2Linked to original sources

Chylous ascites following retroperitoneal lymphadenectomy for granulosa cell tumor of the testis.

We report on an infant with chylous ascites following retroperitoneal lymphadenectomy for granulosa cell tumor of the testis. Granulosa cell tumor of the testis is an extremely rare lesion, with only 8 cases reported previously, including 1 in an infant. Chylous ascites is a rare problem in children and it has been reported in only 92 cases. The options for management of this difficult problem are discussed.

Chylous Ascites↗

Macrocytic megakaryocytes in cultures of S1/S1d bone marrow.

The thrombocytopoietic system of S1/S1d mice is characterized by macromegakaryocytosis and megakaryocytopenia, but the mechanisms responsible for reciprocal abnormalities of megakaryocyte number and size are unknown. These mice have a genetically determined abnormality of their hemopoietic microenvironment that can, in part, be reproduced as abnormal adherent stromal cells in bone marrow cultures. Cultures of bone marrow were therefore done to determine if the megakaryocytic abnormalities of S1/S1d marrow would also be reproduced in them. Cultures composed entirely of S1/S1d cells showed persistent macrocytosis of megakaryocytes when compared with cultures of normal +/+ marrow. At various times of culture, there were also reduced numbers of megakaryocytes, total cells, and granulocytes in the supernatants of S1/S1d cultures. Mixed cultures of S1/S1d and +/+ cells yielded inconclusive findings. The fact that macromegakaryocytosis occurred in cultures of S1/S1d marrow strongly suggests that its in vivo determinants were, in part, reproduced in culture.

Acetylcholinesterase↗

HL-A histocompatibility antigens in recurrent aphthous ulceration.

The frequency of HL-A phenotypes has been investigated in 64 patients who had recurrent aphthous ulcers and 100 subjects who did not. The HL-A phenotypes were determined by a two-step microcytotoxicity test on peripheral blood lymphocytes, incubating these cells with a range of defined antiserums and complement and subsequently assessing lymphocyte viability by dye exclusion. There were no significant differences between the frequency of individual HL-A antigens in the patients with aphthous ulceration and those of subjects without aphthous ulceration. Similarly, no differences in numbers of shared antigens could be demonstrated. The distribution of HL-A antigens was essentially similar in subdivisions of patients with aphthous ulceration, grouped on the basis of sex, family history, age at onset, and maximum number of concurrent ulcers and their duration before healing.

Cytotoxicity Tests, Immunologic↗

Determination of loading parameters in the canine hip in vivo.

The loading parameters in the canine hip were determined from multiple studies, involving the collection of kinematic and force plate data in vivo joint reaction force from an instrumented hip replacement prosthesis, and in vivo femoral cortical bone strain gauge data in different dogs. In the middle of the stance phase of gait the canine femur was flexed 110 degrees with respect to the pelvis and formed a 20 degree angle relative to the floor. At this point in the gait cycle, a line passing from the superior to the inferior aspect of the pubic symphysis was parallel to the floor. The joint reaction force measurements showed that the net force vector during midstance was directed inferiorly, posteriorly, and laterally, with a peak magnitude of up to 1.65 times the body weight. A torsional moment of 1.6 N m is exerted about the femoral shaft. In vivo strain data showed that during gait peak compressive strains of -300 to -502 microstrain were produced on the medial aspect of the femoral cortex and peak tensile strains of +250 to +458 midstrain were produced on the femoral cortex. At the midstance phase of gait, principal cortical bone strains were rotated up to 29 degrees relative to the long axis of the femur, suggesting torsional loads on the femur. These data in combination provide valuable insights on the loading parameters of the canine hip which can be used in future applications of the canine as a model for evaluating mechanically based phenomena such as bone ingrowth and remodeling or hip prostheses.

Animals↗