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Biomedical subjects

C Elliott

Publications and source records attributed to C Elliott.

At least 109 records · Page 6Linked to original sources
PubMed1985

Initiation of locomotion from the mesencephalic locomotor region: effects of selective brainstem lesions.

The effects of selected brainstem lesions on controlled treadmill locomotion produced by stimulation of the mesencephalic locomotor region (MLR) in postmamillary cats were determined in these experiments. The importance for the initiation of locomotion of projections from the MLR to rostral brainstem structures, described in a preceding paper, were examined by selective lesioning or by adjusting the level of the decerebration. The role played by the lateral vestibulospinal tract (LVST) in the initiation of locomotion was examined by lesioning Deiters' nucleus bilaterally. Contrary to previous claims, the results of the present experiments show that areas of the brainstem rostral to the MLR are not required for the initiation of locomotion by MLR stimulation. This finding eliminates the ventral tegmental area of Tsai and the substantia nigra, both implicated in the initiation of locomotion, as required participants in MLR stimulated locomotion. Bilateral Deiters' nucleus (DN) lesions did not significantly affect the initiation of locomotion from the MLR, nor did such lesions alter in a systematic fashion the amplitude or timing of EMG activity in flexor or extensor muscles of the hindlimb during MLR evoked walking. Joint angle changes during the locomotor cycle were also essentially unaltered by DN lesions. The significance of these findings regarding the brainstem structures which must be involved in the initiation of locomotion are discussed.

Animals↗
PubMed1985

Fluorescent monitoring of proteins during sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting.

Fluorescent labeling of proteins was found to be a very sensitive and reliable alternative to conventional methods for monitoring proteins on Western blots. Proteins were labeled with 2-methoxy-2,4-diphenyl-3(2H)-furanone (MDPF) before SDS-PAGE. After electrophoresis and subsequent electro-blotting the fluorescent-labeled proteins were visible upon ultraviolet illumination of the nitrocellulose membranes, and could be photographed to yield an accurate record of the blots before subsequent serological analysis. The sensitivity for detecting MDPF-labeled proteins on nitrocellulose was 100-200 ng, 50 to 100 fold less sensitive than on gels. Fluorescent-labeled TMV and MStpV capsid proteins that were blotted onto nitrocellulose still reacted in serological tests and were detected when present in quantities as low as 100 pg. Fluorescent labeling allows accurate photographic records of the SDS-gel, blot and probed blot using only one sample, and no subsequent staining steps are required.

Animals↗
PubMed1984

Solubilisation of human erythrocyte band 4.1 protein in the non-ionic detergent Tween 20.

Extraction of spectrin-depleted erythrocyte membranes with the non-ionic detergent Tween 20, in a 0.1 M glycine-NaOH buffer (pH 9.8) leads to the solubilization of band 4.1 and the sialoglycoproteins. The comigration of band 4.1 with the sialoglycoproteins in gel filtration and detergent-free electrophoresis indicated that these proteins may be associated as complexes of high molecular weight. Although treatment of intact membranes with Tween 20 under the same conditions does not lead to direct solubilization of proteins, severe disruption of the membranes was observed under phase contrast microscopy. Suspension of the treated membranes in 5 mM phosphate buffer (pH 8.0) leads to the solubilization of band 4.1, spectrin, actin and the sialoglycoproteins. High molecular weight complexes of band 4.1 and the sialoglycoproteins were isolated from these extracts, suggesting a possible interaction between band 4.1 and sialoglycoproteins which may be important for linking the cytoskeleton to the membrane.

Blood Proteins↗
PubMed1984

Adipocyte insulin-binding species: the 40 A Stoke's radius protein.

Several laboratories have demonstrated the presence of large (70 A) (1 A = 0.1 nm) and small (40 A) insulin receptors. This report provides evidence that the 40 A insulin receptor migrates on dodecyl sulfate - acrylamide gel electrophoresis as a 90 000 dalton protein and that this protein is a single polypeptide chain. 125I-labeled insulin was bound to plasma membranes from isolated rat adipocytes. Following removal of unbound 125I-labeled insulin, the mixture was exposed to disuccinimidyl suberate. Proteins tagged with 125I-labeled insulin were separated by dodecyl sulfate gel electrophoresis or Sepharose 6B chromatography. Autoradiography of the gels demonstrated several large (relative mass (Mr) greater than 300 000) and one small (Mr approximately 90 000) labeled protein in nonreduced membrane proteins. Dithiothreitol reduction decreased the large insulin-binding species to its known subunits, but the 90 000 dalton protein did not decrease in size. Triton X-100 solubilized plasma membranes were separated by Sepharose 6B chromatography. One labeled protein, with Kav = 0.57 elution position, on dodecyl sulfate gel electrophoresis migrated as a 90 000 dalton protein. Thus, rat adipocyte plasma membranes contain both an oligomeric insulin-binding species and a monomeric insulin-binding species. The relationship of the monomeric to the oligomeric insulin receptor is discussed.

Adipose Tissue↗
PubMed1983

Adipocyte insulin-binding species: the size and subunit composition of the larger binding species.

Several investigators have reported that there are both large and small insulin-binding proteins in plasma membranes; the larger protein demonstrates nonlinear Scatchard binding, and the smaller protein has linear binding. We now present evidence that the larger insulin-binding species consists of four proteins of different sizes. Rat epididymal adipocyte plasma membranes were prebound with 125I-insulin and then exposed to 1 mM disuccinimidyl suberate for 15 min at 2 degrees C. The membranes were solubilized in 0.1% Triton X-100 and applied to a Sepharose 6B column. Peaks of radioactivity from the column were dialyzed, lyophilized, and analyzed by dodecyl-sulphate gel electrophoresis (5%, 100/l; mono/bisacrylamide). Autoradiograms of the gels were scanned with a densitometer. The Sepharose chromatogram revealed four radioactive peaks: peak 1 at column void volume; peak 2, Kav = 0.27; peak 3, Kav = 0.77; and peak 4, Kav = 1.09. Dodecyl sulphate electrophoresis of fractions in peak 2 demonstrated four bands on autoradiography; peak 1 did not enter the gel and peaks 3 and 4 ran with the dye front. Molecular weight estimates of the four insulin-binding species in peak 2 were 600, 500, 420, and 350 K. On dithiothreitol reduction each insulin-binding species yielded subunits of Mr approximately equal to 135 and 18 K. The three largest binding species demonstrated an additional 45-K dalton protein on dithiothreitol reduction, and the 500-K and 420-K binding species also yielded a 49-K dalton protein. These results suggest that the large insulin-binding protein in rat epididymal adipocytes contains several insulin-binding species, and that these insulin-binding species differ in the number of and the type of subunits they contain. In addition, it may be postulated that the nonlinear Scatchard binding associated with the larger binding protein is a consequence of the heterogeneity of the insulin-binding species in this Sepharose peak.

Adipose Tissue↗
PubMed1983

The accumulation of putrescine and paraquat into lung slices taken from BHT treated mice.

Putrescine and paraquat have been shown to accumulate in slices of mouse lung by a process which obeys saturation kinetics. The Vmax for the process was similar for both compounds (1.18 and 1.29 mumol/g wet wt/h) although the apparent Km for putrescine was 15 microM compared with 209 microM for paraquat. Mice were given a range of doses of BHT (i.p.) and the sequence and nature of the changes in morphology of the lung determined by light and electron microscopy. Lung slices were prepared from mice given BHT, and their ability to accumulate both paraquat and putrescine was determined. Within 4 days of dosing with 200 mg BHT/kg, there was marked cellular proliferation in the lung with an increase in the number of type II epithelial cells. Seven days after dosing the lungs had generally returned to their normal morphology with only occasional areas in some lungs showing evidence of damage. Between 1 day and 7 days after dosing, slices of mouse lung showed a reduced ability to accumulate paraquat or putrescine. This did not return to control values until 14 days. The greatest reduction in the accumulation of either compound was seen 4 days after dosing when the proliferation of the type II epithelial cells was most marked. Mice given 150 mg BHT/kg showed similar but less extensive morphological change and the ability of lung cells from these mice to accumulate paraquat or putrescine was not as severely reduced compared with mice given 200 mg BHT/kg. With doses of 100 mg BHT/kg the accumulation of paraquat and putrescine was only slightly reduced and there was a correspondingly minimal affect on lung morphology. The lungs of mice given 50 mg BHT/kg were unaffected as was their ability to accumulate either compound. The results from this study, when taken in the context of previously reported data, support the conclusion that paraquat is accumulated into the lung by a process responsible for the uptake of putrescine. In the rat, paraquat and putrescine are known to accumulate in alveolar type II cells and therefore it appears that the regenerating alveolar type II epithelial cell is functionally unable to accumulate these compounds and may be considered physiologically similar to type II epithelial cells in immature animals.

Animals↗
PubMed1981

Synthesis and assay for activity of a proposed anorexogenic agent, L-pyroglutamyl-L-histidyl-glycine.

L-Pyroglutamyl-L-histidyl-glycine has been reported to be an anorexogenic agent in female mice. In this report the synthesis of this tripeptide is described. The synthetic material was injected into female and male mice and into male rats. In no instance did the animals decrease their food intake. Further, the weights of peptide-treated animals were the same as those of control (saline-treated) animals. The results suggest that L-pyroglutamyl-L-histidyl-glycine is not an anorexogenic agent.

Animals↗
PubMed1981

Influence of streptozitocin-induced diabetes on glycosyltransferase activities in plasma and renal cortex.

The collagen glucosyltransferase of renal cortex is increased in experimental diabetes and this increased may be partially reversed or prevented by insulin treatment. The absence of any consistent increase in the plasma collagen glucosyltransferase level in diabetes argues against the enzyme's having a significant role in the pathological thickening of capillary basement membranes. The biological significance of the increased renal glucosyltransferase activity in chemically-induced diabetes must therefore remain in doubt but it is possible that the high glucose concentration in the blood simply stimulates the synthesis of new enzyme protein in the kidney.

Animals↗
PubMed1980

Economic aspects of village health.

Given the poor quantity and quality of medical care in most villages in the developing countries, the economic determinants of village health are the supply of labour, the cash flow associated with that labour and the availability of land. The paper examines these in the three classical 'time periods', arguing that inability to meet labour peaks is of great significance in explaining seasonal shortage of food and chronic shortage of cash. It also explains community indifference to upkeep of social overhead capital. Substitution of capital goods for labour is socially differentiated, not least by labour availability, and leads inevitably to a regressive distribution of land and the creation or enlargement of a class of landless labourers. Under certain limited conditions this class may enjoy a rising real income with associated health-promotive expenditures. The more normal case, however, is extreme poverty, whether rural or urban, with all that that implies for the undermining of health. Land reform therefore becomes a necessary precondition of health promotion.

Agriculture↗
PubMed1979

"How am I doing?".

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Chronic Disease↗
PubMed1979

Combined hyperlipidemia and hypertriglyceridemia in renal allograft recipients. Comparison with non-renal combined hyperlipidemic or hypertriglyceridemic patients and normal subjects.

In order to investigate the degree of similarity between renal transplant and non-renal combined hyperlipidemic and hypertriglyceridemic patients, serum and lipoprotein lipid compositions were compared in transplant and non-renal combined hyperlipidemic and in transplant and non-renal hypertriglyceridemic patients, and normal subjects. Although certain similarities were demonstrated, combined hyperlipidemia in transplants differed from that in non-renal patients in a number of respects: (1) LDL-triglyceride levels were increased to a greater extent in transplant than in non-renal patients in females, while LDL-phospholipid was elevated in male transplants only; (2) HDL-cholesterol levels were raised in transplants relative to non-renal patients in females, and relative to both non-renal patients and normal subjects in males; (3) a number of differences in lipoprotein-lipid ratios between transplant and non-renal patients were demonstrated for all three lipoprotein fractions. In hypertriglyceridemia, changes in lipoprotein-lipid levels were similar in transplant and non-renal patients with the exception of HDL-cholesterol levels, which were decreased in non-renal patients only. Furthermore, the ratio of esterified to free cholesterol in LDL and HDL was decreased in non-renal but not in transplant patients. The data presented demonstrate that, despite certain similarities, a number of the lipoprotein-lipid changes observed in transplant combined hyperlipidemia and in transplant hypertriglyceridemia differ from those observed in non-renal patients with similarly elevated serum lipids.

Adult↗