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Biomedical subjects

W D Lust

Publications and source records attributed to W D Lust.

At least 91 records · Page 5Linked to original sources
PubMed1975

Glycolytic metabolism in cultured cells of the nervous system. II. Regulation of pyruvate and lactate metabolism in the C-6 glioma cell line.

Pyruvate and lactate efflux from C-6 glioma cells has been found to be regulated by both the medium glucose concentration and the medium concentration of the two acids. Each moves down a concentration gradient until the extracellular level is in equilibrium with the intracellular. Long-term growth studies demonstrated that the cells preferentially utilize glucose but that once it is depleted, they will take up first pyruvate, followed by lactate, for further metabolism. Changes in the intracellular levels of the two metabolites correspond to those seen in the medium. The rate of glycogen breakdown parallels that of medium glucose ultilization. Preliminary results with the C-1300 neuroblastoma cells showed pyruvate and lactate efflux rates comparable to those of the glioma cells.

Cell Division↗
PubMed1975

Glycolytic metabolism in cultured cells of the nervous system. III. The effects of thiamine deficiency and pyrithiamine on the C-6 glioma and C-1300 neuroblastoma cell lines.

The effects of thiamine deficiency and of the antithiamine drug pyrithiamine on the C-6 glioma and the C-1300 neuroblastoma cell lines have been studied. Thiamine deficiency increased the doubling time of the neuroblastoma cells without affecting that of the glioma cells. Pyrithiamine prevented both cell lines from doubling even once. (hiamine deficiency had only slight effects on intracellular pyruvate and lactate levels or on efflux rates for the acids, but pyrithiamine treatment resulted in large increases in both the intracellular levels and the efflux in both cell lines. For comparison, the pyruvate and lactate levels in mouse brain were measured. The levels from thiamine-deficient mouse brain were essentially unchanged from controls while pyrithiamine treatment caused a significant elevation only of the pyruvate concentration.

Animals↗
PubMed1975

Glycolytic metabolism in cultured cells of the nervous system. I. Glucose transport and metabolism in the C-6 glioma cell line.

The transport and metabolism of glucose was examined in monolayers of C-6 glioma cells. 1) Glucose transport appeared to have both a low (Km = 7.74 mM) and a high (Km = 1.16 mM) affinity site in C-6cells; whereas 2-deoxyglucose had only one (Km = 3.7 mM). 2) A large portion of the accumulated glucose was rapidly metabolized to the two glycolytic end products, lactate and pyruvate, and then extruded into the medium. The temperature-dependent efflux of lactate and pyruvate was linear up to 2 hrs with 6 to 10 times more lactate being extruded into the medium than pyruvate. 3) The efflux of lactate and pyruvate increased with increasing extracellular (medium) pH. The presence of 5 percent CO2 not only inhibited the acid efflux but also inhibited the short-term uptake of glucose. The CO2 effect was attributed to a lowering of the medium pH since bicarbonate alone either increased or did not inhibit efflux. 4) Valinomycin increased the levels of cellular lactate but not those of pyruvate by almost three-fold. Lactate efflux was stimulated while that of pyruvate was inhibited. The addition of 5 percent CO2 increased the cellular levels of both lactate and pyruvate, but unlike valinomycin decreased the acid efflux. Idoacetate inhibited the acid efflux by 50 percent suggesting that glycolysis is necessary for efflux.

Acetone↗
PubMed1973

Cyclic adenosine monphosphate, metabolites, and phosphorylase in neural tissue: a comparison a methods of fixation.

Fixation of rat brain tissue by freeze-blowing, microwave irradiation, immersion of whole rats in liquid nitrogen, and decapitation into liquid nitrogen indicates that postmortem changes in metabolites and enzyme forms are minimal in freeze-blown brains. Cyclic adenosine monophosphate levels are lowest in microwave-irradiated brains, which has been interpreted by some investigators to indicate rapid fixation and minimal anoxia. However, the changes in phosphocreatine, adenosine triphosphate, lactate, and phosphorylase clearly demonstrate that fixation by freeze-blowing or immersion in liquid nitrogen more closely approximate the state in vivo.

Adenosine Triphosphate↗
PubMed1970

Elevated concentration of adenosine 3':5'-cyclic monophosphate in intestinal mucosa after treatment with cholera toxin.

A heat-labile factor in cell-free filtrate of a Vibrio cholerae culture induces a marked rise in the wet-weight concentration of adenosine 3':5'-cyclic monophosphate (cyclic AMP) in the intestinal mucosa of the dog. The increase becomes appreciable 1-1.5 hr after intraluminal administration of the filtrate, about the same time as the onset of intestinal secretion in response to a heat-labile enterotoxin in the filtrate. These results are consistent with the hypothesis that cyclic AMP may be an intermediary in the intestinal secretory response to cholera toxin.

Animals↗
PubMedDate not supplied

Protein kinase C activity in permanent focal cerebral ischemia.

Protein kinase C (PKC) activity was investigated in a model of focal stroke in the rat. Following 6 h of left middle cerebral artery occlusion, rat brains were frozen in situ. In the peripheral ischemic zone, total PKC activity declined by close to two-thirds (1.07 +/- 0.35 vs 2.77 +/- 0.12 nmol/min/mg protein; p less than 0.05, n = 4), and the proportion of total activity associated with the particulate fraction decreased from 33.3 +/- 1.5% to 16.2 +/- 1.4% (p less than 0.01, n = 4). Thus, overall particulate PKC activity in the ischemic zone was less than 20% of control. The cerebral energy metabolite profile of tissue from the ipsilateral hemisphere, corresponding to the region where samples were obtained for PKC activity assay, suggests that this tissue may have been part of the ischemic penumbra before further deterioration.

Adenosine Triphosphate↗