Search PubMed⌕ Search

Biomedical subjects

C Ross

Publications and source records attributed to C Ross.

At least 163 records · Page 9Linked to original sources
PubMed1969

Oligomycin inhibition of phosphate uptake and ATP labeling in excised maize roots.

ATP labeling by newly absorbed (32)P in excised maize roots was reduced 34% by the presence of oligomycin during a 4-min uptake period with no reduction in rate of phosphorus absorption. Longer exposure to oligomycin, during pretreatment periods or longer uptake periods, reduced phosphorus absorption and further reduced ATP synthesis. In these tissues it appears that oligomycin inhibits ATP production at the mitochondria, that ATP is the energy source for phosphorus uptake at the plasmalemma, and that a depletion in the ATP supply causes a reduced rate of uptake.

Journal Article↗
PubMed1968

Metabolism of cytidine and uridine in bean leaves.

The metabolism of cytidine-2-(14)C and uridine-2-(14)C was studied in discs cut from leaflets of bean plants (Phaseolus vulgaris L.). Cytidine was degraded to carbon dioxide and incorporated into RNA at about the same rates as was uridine. Both nucleosides were converted into the same soluble nucleotides, principally uridine diphosphate glucose, suggesting that cytidine was rapidly deaminated to uridine and then metabolized along the same pathways. However, cytidine was converted to cytidine diphosphate and cytidine triphosphate more effectively than was uridine. Cytidine also was converted into cytidylic acid of RNA much more extensively and into RNA uridylic acid less extensively than was uridine. Azaserine, an antagonist of reactions involving glutamine (including the conversion of uridine triphosphate to cytidine triphosphate), inhibited the conversion of cytidine into RNA uridylic acid with less effect on its incorporation into cytidylic acid. On the other hand, it inhibited the conversion of orotic acid into RNA cytidylic acid much more than into uridylic acid. The results suggest that cytidine is in part metabolized by direct conversion to uridine and in part by conversion to cytidine triphosphate through reactions not involving uridine nucleotides.

Journal Article↗
PubMed1967

Orotidine-5'-phosphate decarboxylase and pyrophosphorylase of bean leaves.

This report includes results demonstrating the existence of orotidine-5'-phosphate decarboxylase and orotidine-5'-phosphate pyrophosphorylase in plant leaves. The decarboxylase enzyme, purified 8 fold from leaves of etiolated pinto beans (Phaseolus vulgaris L.), had a pH optimum of 6.3. It was strongly inhibited by 6-azauridine-5'-phosphate; a concentration of 12 mum decreased the reaction rate 60%. The enzyme was not dependent upon magnesium ions or inhibited by p-chloromercuribenzoate. It was present in other parts of the bean plant and was found in young leaves of tomato (Lycopersicon esculentum Mill.) and Canada thistle (Cirsium arvense L.)The enzyme orotidine-5'-phosphate pyrophosphorylase, which catalyzes the formation of orotidine-5'-phosphate from orotic acid and 5-phosphoribosyl-1-pyrophosphate, was found in the etiolated bean leaves, and was also present in the leaves of tomato and Canada thistle. It was stimulated by manganous or magnesium ions and had a pH optimum of 7.2. The K(m) value obtained by varying the concentrations of 5-phosphoribosyl-1-pyrophosphate was 75 mum, and when orotic acid was varied the resulting K(m) was 3.5 mum. The presence of these 2 enzymes in higher plants, combined with previous results with inhibitors and labeled metabolites, indicates that the normal pathway of pyrimidine nucleotide synthesis in higher plants proceeds through orotic acid and OMP.

Carboxy-Lyases↗
PubMed1966

Inhibition of leaf process by p-fluorophenylalanine during induction of flowering in the cocklebur.

The amino acid antimetabolite, DL-p-fluorophenylalanine (FPA), inhibited induction of flowering in the short-day cocklebur plant, Xanthium pensylvanicum Wall., primarily by interfering with processes occurring during the inductive dark period. At the concentrations used the inhibitor had little effect on subsequent vegetative development of the plant.The inhibition was largely reversed (internally) by L-phenylalanine, but not by D-phenylalanine nor by DL-tyrosine. The FPA strongly inhibited the absorption of labeled phenylalanine, leucine, and glycine, and inhibited the conversion of phenylalanine into protein in experiments where incorporation was separated in time from effects upon absorption. The FPA, too, was incorporated into protein, at nearly half the rate of phenylalanine. Neither D- nor L-phenylalanine significantly interfered with absorption of FPA, showing the FPA did not affect amino acid absorption by simple competition for a common carrier site. It was concluded that FPA may affect flower induction because of its interference with normal enzyme synthesis, although effects on other processes might also be involved.

Antimetabolites↗
PubMedDate not supplied

Role of LFA-1/ICAM-1, CLA/E-selectin and VLA-4/VCAM-1 pathways in recruiting leukocytes to the various regions of the chronic leg ulcer.

The center, edge and distant regions of the venous leg ulcer differ in inflammatory cell composition, suggesting that these represent different developmental stages. Our goal was to determine which recruitment pathways contribute to the differences in leukocyte composition between the various ulcer regions. The multiple region biopsy approach, which enables to study the different development phases of the ulcer at one time-point, was employed to immunohistochemically identify the vascular adhesion molecules E-selectin, intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1), and their counter-ligands on extravasated leukocyte cutaneous lymphocyte-associated antigen (CLA), lymphocyte function-associated antigen (LFA-1) and very late activation antigen-4 (VLA-4), respectively. E-selectin expression was highest at the ulcer edge, while ICAM-1 was highest at the ulcer center. VCAM-1 expression was minor at all ulcer regions. CLA stained up to 80% of the epidermal Langerhans' cells, 62% of the T cells, and only 9% of the macrophages. LFA-1 did not stain Langerhans' cells, stained up to 89% of the T cells and up to 11% of the macrophages. VLA-4 stained up to 30% of the T cells and 71% of the macrophages. In conclusion, the results indicate that Langerhans' cells, T cells and macrophage are each recruited by more than one adhesion-molecule pathway to any of the chronic venous leg ulcer regions.

Adult↗
PubMedDate not supplied

Stigma and ageism: compounding influences in making an accurate mental health assessment.

Stigma and ageism are two phenomena that greatly affect the accurate assessment of mentally ill elderly and, ultimately, their health care. Healthcare providers, doctors, nurses and others, including mental-healthcare providers, would benefit from awareness of stigma and ageism and their impact on psychiatric care for the elderly, many of whom also have physical problems. Understanding these influences may assist providers to make more accurate diagnoses and a more appropriate plan of care. This paper defines stigma and ageism and their potential and actual influences on assessment and interventions for the mentally ill elderly. Strategies for overcoming the impact of stigma and ageism are presented to assist healthcare providers to advocate for geropsychiatric clients.

Aged↗