Biomedical subjects
J Torrance
Publications and source records attributed to J Torrance.
Severe expiratory obstruction on a Siemens Servo 300 mechanical ventilator.
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Protein kinases in human lymphocytes: electrophoretic study of multiple forms.
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Characteristics of iron exchange between transferrin and hepatocytes in culture.
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The fate of intravenously administered hepatic ferritin in normal, phenylhydrazine-treated and scorbutic guinea-pigs.
When highly purified hepatic 59Fe-ferritin was injected intravenously into normal guinea-pigs more than half of it was taken up by red cell precursors and the iron was used for haem formation. This was studied in more detail in animals in which a reticulocytosis had been induced either by phenylhydrazine or by repeated venescetions. 55% of the injected ferritin iron was found in reticulocytes at 1 h. Experiments using ferritin doubly labelled with 59Fe and 125I indicated that the whole molecule was taken up, with two-thirds of the radioactivity being associated with the membrane at 1 h and one third being already within the cell. There was a progressive loss of 125I activity over the ensuing hours, while most of the 59Fe was slowly internalized and incorporated into haem between 1 and 24 h. In contrast, 90% of the activity taken up by red cell precursors from 59Fe-transferrin was present as haem at all times. The liver and spleen were the two other major sites of 59Fe-ferritin uptake in phenylhydrazine treated animals. While there was an early uptake of 59Fe into haem in these organs, some redistribution occurred with time, since most of the 59Fe was in a non-haem fraction by 24 h. In a final experiment the distribution and fate of 59Fe-ferritin was studied in scorbutic animals treated with phenylhydrazine. The findings were similar to those in normals similarly treated, which suggests that ferritin iron was being effectively mobilized for haem formation despite the ascorbic acid depletion.
Localization of hyaluronate and hyaluronate-binding protein on motile and non-motile fibroblasts.
The distribution of a hyaluronate-binding (HABP) and rhodamine B-isothiocyanate (RITC)-labeled hyaluronate (HA) were studied on both actively motile and stationary chick heart fibroblasts to assess the relationship of these molecules to each other, to other extracellular matrix molecules, to membrane protrusions and to adhesion sites. RITC-HA and HABP, detected by indirect immunofluorescence, were concentrated in the perinuclear region, the leading lamella and retraction processes of actively motile cells, although RITC-HA also occurred diffusely over the rest of the cell body. Double immunofluorescence confirmed that HA and HABP co-localized in the former three regions, suggesting that, at these locations, the HABP may act as a cell surface-binding site for HA. With increasing culture confluency and consequent slowing of fibroblast motility, the localization of both polymers changed to a uniform and diffuse distribution over the cell body and processes. On actively motile cells, RITC-HA and HABP did not co-distribute with fibronectin, heparan sulfate proteoglycan or laminin. Areas coated with RITC-HA and HABP often contained specialized adhesion sites as determined by interference reflection microscopy (IRM) but neither polymer appeared to particularly localize to adhesion sites. However, the occurrence of RITC-HA and HABP in the leading lamellae of motile cells consistently coincided with ruffling activity. These results are discussed with respect to a possible instructive role of HA in cell motility.
Effect of desferrioxamine, rhodotorulic acid and cholylhydroxamic acid on transferrin and iron exchange with hepatocytes in culture.
The mechanism of action of the hydroxamate iron chelators desferrioxamine (DFO), rhodotorulic acid (RHA) and cholylhydroxamic acid (CHA) was studied using rat hepatocytes in culture. Each chelator affected both the uptake and, to a much smaller extent, the release of transferrin-125I-59Fe from the cells. All chelators reduced the 59Fe uptake and incorporation into ferritin in a concentration-dependent manner. Uptake of 59Fe into the membrane (stromal-mitochondrial) fraction was also decreased by DFO and RHA but increased by CHA. Transferrin-125I binding was reduced slightly by DFO and RHA and increased by CHA. All chelators released 59Fe transferrin-125I from hepatocytes prelabelled by incubation with rat transferrin-125I-59Fe and washed before reincubation in the presence of the chelators. DFO decreased membrane 59Fe but had little effect on ferritin-59Fe. RHA decreased 59Fe in both membrane and ferritin fractions. CHA decreased hepatocyte-59Fe but increased 59Fe in the hepatocyte membrane fraction. Higher concentrations of the chelators had little further effect on 59Fe release but promoted transferrin-125I release from hepatocytes. All chelators appeared to act on kinetically important iron pools of limited size and hence are likely to be most effective when given by continuous infusion rather than bolus injection.
The importance of gastric hydrochloric acid in the absorption of nonheme food iron.
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A simple rapid radiometric assay for pyrimidine-5'-nucleotidase.
Pyrimidine-5'-nucleotidase deficiency appears to be an important cause of hemolytic anemia associated with basophilic stippling of the red cells. A new radiometric method for the assay of this enzyme has been developed. In this technique, 14C-CMP serves as substrate. The CMP which is not dephosphorylated to cytidine is bound to the barium sulfate precipitate which forms in the deproteinization process. The cytidine remains in solution and is counted. The method is simple and reproducible and can be carried out on large numbers of samples. Two patients with pyrimidine-5'-nucleotidase deficiency have been detected by means of this technique.
Intraerythrocytic adaptation to anemia.
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Effect of altitude on oxygen binding by hemoglobin and on organic phosphate levels.
The relationship between oxygen dissociation and 2,3-diphosphoglycerate (2,3-DPG) in the red cell has been studied in subjects moving from low to high altitude and vice versa. Within 24 hr following the change in altitude there was a change in hemoglobin affinity for oxygen; this modification therefore represents an important rapid adaptive mechanism to anoxia. A parallel change occurred in the organic phosphate content of the red cell. While this study does not provide direct evidence of a cause-effect relationship, the data strongly suggest that with anoxia, the observed rise in organic phosphate content of the red cell is responsible for increased availability of oxygen to tissues.