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Biomedical subjects

J D Russell

Publications and source records attributed to J D Russell.

72 records · Page 4Linked to original sources
PubMed1981

Collagen synthesis in human fibroblasts: effects of ascorbic acid and regulation by hydrocortisone.

The effects of hydrocortisone and ascorbic acid on collagen and noncollagen protein synthesis, and on growth were examined in fibroblasts derived from normal human dermis. When the medium was supplemented with 0.28 mM ascorbic acid, the apparent rate of collagen production increased 2-3 fold over the culture cycle. Ascorbic acid also caused a small increase in the apparent rate of synthesis of noncollagen protein and an elevation in growth rate and maximum cell density. Growth was not required for the increase in collagen production since addition of ascorbate to confluent cultures induced a similar increase. Hydrocortisone (1.5 microM) blocked the ascorbate-related increase in collagen production during growth and in confluent cultures. The hormone simultaneously increased the apparent rate of noncollagen protein production and maximum cell density, suggesting that the effect on collagen synthesis was specific. Inhibition of collagen production by hydrocortisone was observed only in the presence of ascorbate, while the increase in growth and noncollagen protein production occurred in the presence and absence of the vitamin.

Ascorbic Acid↗
PubMed1981

Affective disorders, diabetes mellitus and lithium.

There appears to be an association between affective disorders and diabetes mellitus independent of the use of lithium in treatment. Prior studies have suggested that lithium treatment may impair glucose tolerance or produce frank diabetes in certain patients. Metabolic complications of the diabetic state, such as hyperosmolality and salt depletion increase lithium absorption and the risk of toxicity even at generally acceptable serum levels. The management of patients with diabetes and affective disorders on prophylactic lithium is discussed.

Animals↗
PubMed1978

Induction of mitochondrial phosphoenolpyruvate carboxykinase in cultured human fibroblasts.

Mitochondria of cultured normal human fibroblast cells were found to contain the enzyme phosphoenolpyruvate carboxykinase. The activity of this enzyme in these cells is increased 2- to 3-fold by addition of 5 . 10(-4) M dibutyryl cyclic AMP, or 1.5- to 2-fold by the addition of dexamethasone (2 . 10(-7) M) or hydrocortisone (1.38 . 10(-6) M). These increases in enzyme activity were inhibited cycloheximide and actinomycin D, suggesting they are dependent upon de novo protein synthesis. Cultured human fibroblasts may thus provide a useful system for studying the regulation of mitochondrial phosphoenolpyruvate carboxykinase.

Bucladesine↗
PubMed1978

Differential effects of hydrocortisone on both growth and collagen metabolism of human fibroblasts from normal and keloid tissue.

Cultured fibroblasts isolated from normal and keloid tissue do not differ in their growth characteristics or in the rate of collagen synthesis under routine culture conditions. The addition of hydrocortisone to the culture media results in significant differences in both growth and collagen synthesis between these cell types. Collagen synthesis is inhibited 60% in normal cultures by hydrocortisone (0,5 micrograms/ml) and the population size at which density-dependent growth inhibition is achieved is increased. Keloid-derived fibroblasts grow to a lower maximum density in the presence of hydrocortisone, while their rate of collagen synthesis is not significantly reduced. The rate of non-collagen protein synthesis is increased significantly by hydrocortisone in both cell types. Comparison of normal and keloid-derived cultures obtained from a single individual suggests that the keloid phenotype with respect to both growth and collagen synthesis is restricted to the fibroblasts isolated from the keloid nodule.

Cell Division↗
PubMed1977

Pyruvate carboxylase and phosphoenopyruvate carboxykinase in cultured human fibroblasts.

The activities of pyruvate carboxylase and phosphoenolpyruvate carboxykinase were measured in cultural human fibroblasts. Considerable variation was observed in strains derived from different individuals. The activities of both enzymes throughout the culture cycle were measured in two strains. In these strains the specific activities of the enzymes increased during log phase and remained constant during the stationary phase. However, one cell strain exhibited a high activity of pyruvate carboxylase which remained unchanged throughout the culture cycle, suggesting that this enzyme may be regulated differently in different strains of cultured human cells. Familial studies suggest that the observed variations in pyruvate carboxylase activity may be due to a genetic polymorphism.

Avidin↗
PubMed1976

Cell size and growth characteristics of cultured fibroblasts isolated from normal and keloid tissue.

No differences in appearance or in cell size distribution were observed between cultured fibroblasts derived from normal skin, mature scars, or keloids. Artifactual differences in cell size distributions between strains can result when populations are compared at different cell densities. Keloid derived fibroblasts remain euploid in culture, and they have the same growth rate and same degree of density-dependent growth inhibition as cultured normal human fibroblasts.

Cells, Cultured↗
PubMedDate not supplied

Development of a central matching system for the allocation of cadaveric kidneys: a simulation of clinical effectiveness versus equity.

OBJECTIVES: 1) To develop a computer-based simulation to prospectively study the impacts of explicitly incorporating different equity criteria into the process of allocating kidneys to recipients, given the scarcity of this resource. 2) To assess the tradeoffs between systems that allocate kidneys based only on medical criteria, systems that allocate kidneys based only on equity criteria, and systems that consider both medical and equity criteria. METHODS: A computer-based simulation was developed that describes the flows of patients and kidneys. This model provides information at various time points about the number of patients in the system who are awaiting transplants, the number of kidneys available for transplantation, the number of transplantations performed for each matching algorithm, and the number of kidneys discarded (when applicable), as well as the means and standard deviations of the HLA-match scores, number of days from registration to transplantation, and number of days (from registration) of those who are still waiting for transplants. Five different matching algorithms were compared, ranging from determination of the allocation by a single medical criterion (i.e, HLA match) to determination by a single equity criterion (i.e., relative position in the waiting queue). The remaining algorithms represent different strategies of weighting these two considerations. Estimates regarding the main parameters of the model were derived utilizing data collected through the Multiple Organ Retrieval and Exchange Programme of Ontario, Canada. RESULTS: The simulation was set to run for a period of ten years. A tradeoff between graft survival (or improved HLA matching) and equal treatment of patients regardless of their likelihood to benefit was found. It is clear that an algorithm that allocates kidneys based only on temporal location of patient on the waiting list is likely to be unacceptable because of the very poor average HLA-match scores that it yields. Pool size was found to be a major determinant in the attainment of optimal matching from a medical perspective. CONCLUSIONS: 1) The final choice about any allocation algorithm to be used requires that a value judgment be made, i.e., how great a reduction in HLA-match score should be traded in order to improve equity score (or vice versa). 2) A computer-based simulation model is a feasible way to prospectively test the impact of any given allocation algorithm on any given system.

Algorithms↗