http://www.jbc.org/content/262/19/9412.full.pdf

Vesicle formation during reticulocyte maturation. Association of plasma membrane activities with released vesicles (exosomes)

Fate of the transferrin receptor during maturation of sheep reticulocytes in vitro: Selective externalization of the receptor

Metabolite profiling by one- and two-dimensional NMR analysis of complex mixtures

Abnormal choline metabolism is emerging as a metabolic hallmark that is associated with oncogenesis and tumour progression. Following transformation, the modulation of enzymes that control anabolic and catabolic pathways causes increased levels of choline-containing precursors and breakdown products of membrane phospholipids. These increased levels are associated with proliferation, and recent studies emphasize the complex reciprocal interactions between oncogenic signalling and choline metabolism. Because choline-containing compounds are detected by non-invasive magnetic resonance spectroscopy (MRS), increased levels of these compounds provide a non-invasive biomarker of transformation, staging and response to therapy. Furthermore, enzymes of choline metabolism, such as choline kinase, present novel targets for image-guided cancer therapy.

/pdf/choline-metabolism-in-malignant-transformation-4s9se90sd8.pdf

Choline metabolism in malignant transformation

The literature describing 31P, 1H, 13C, 23Na and 19F MRS in vivo in human cancers is reviewed. Cancers have typical metabolic characteristics in 31P and 1H MRS including high levels of phospholipid metabolites and a cellular pH more alkaline than normal. These alone are not specific for cancer but are diagnostic in appropriate clinical settings. Some metabolic characteristics appear to be prognostic indices and correlation with treatment response is emerging as an important potentially cost-effective use of MRS in oncology. 19F MRS examines pharmacokinetics of 5-fluorouracil and by demonstrating its retention predicts response of a cancer to treatment. Current needs include improvement of diagnostic specificity by use of techniques like multivoxel MRS, proton decoupling of 31P, short echo time and fat-suppressed 1H MRS, 13C MRS direct or via 1H-observe, and statistical analysis of multiple spectral features. Trials in large populations in well defined clinical settings are needed to determine if MRS can provide independent prognostic indices useful in cancer management.

Studies of human tumors by MRS: a review.

NMR study of in vivo RIF-1 tumors: Analysis of perchloric acid extracts and identification of 1H, 31P and 13C resonances

Red blood cells from neonatal calves, but not from adult cows, rapidly hemolyze in buffered 300 mM solutions of a variety of nonelectrolytes and amino acids. Of these compounds, sucrose is chosen to elucidate the mechanism by which this preferential hemolysis takes place. As in other mammalian red cells, both calf and cow cells are found to be impermeable to sucrose and, in an isosmolar sucrose solution, to undergo volume shrinkage caused by the net loss of chloride ions with concomitant increase in intracellular pH. To test the potential role of intracellular pH change associated with chloride loss in promoting hemolysis, intracellular pH was altered by: (a) a direct addition of fixed acid or base to sucrose solution; (b) the removal of dissolved CO(2) from sucrose solution; and (c) the addition of cells to isotonic NaHCO(3) solution in the absence of sucrose. In all cases, only calf and not cow cells underwent hemolysis. Moreover, 4-acetamido-4’-isothiocyano-2,2’-stilbene disulfonic acid, a potent anion transport inhibitor, completely protected calf cells from hemolysis and caused a nearly total inhibition of both chloride loss and intracellular alkalinization. Furthermore, the hemolytic process is closely related to the integrity of a membrane protein, the band 3 protein, which can be cleaved to varying degrees by the combined treatment of pronase and lipase. Hemolysis is progressively inhibited as the band 3 protein undergoes proteolysis, until a total inhibition of hemolysis takes place when almost all of the band 3 protein is digested into smaller protein components with a mol wt of 65,000 and 35,000 daltons. These results suggest that the intracellular alkalinization process leading to a structural instability of the membrane band 3 protein is responsible for this calf cell hemolysis.

/pdf/preferential-hemolysis-of-postnatal-calf-red-cells-induced-1n3ip33q8f.pdf

Preferential hemolysis of postnatal calf red cells induced by internal alkalinization.

Naturally occurring reticulocytes of week old piglets were used to characterize the maturation process under in vitro conditions. When the reticulocytes were suspended in tissue culture medium fortified with metabolic substrates, nearly all cells were viable after 24 hours incubation and usually more than 85% of the initial cell population survived after an 80 hour period. In cells maintained as long as a week in incubation, an adequate level of total adenine nucleotide with a large accumulation of IMP was found. In most cases, reticulocytes lose their reticular materials within two days and assume normal erythrocyte configuration. Concomitant with the morphological change, the cell volume decreases toward normal erythrocyte size, the extent of which can be accounted for by the intracellular loss of salt and accompanying water. As in the in vivo reticulocyte maturation process, reticulocytes undergoing in vitro maturation lose their membrane permeability to glucose. These findings suggest that the process of reticulocyte maturation occurring in cell culture approaches that which naturally occurs in vivo. Thus, these cells may be used to delineate the mechanism of the loss of membrane transport of glucose which normally occurs in the adult pig cells.

Pig reticulocytes. IV. In vitro maturation of naturally occurring reticulocytes with permeability loss to glucose

The erythrocytes of the short-beaked echidna (Tachyglossus aculeatus), an egg-laying mammal, were examined for the presence of phosphorylated compounds. The erythrocytes contained only 0.03 +/- 0.01 micromoles of adenosine 5'-triphosphate per milliliter of cells. This amount is two orders of magnitude less than that in human cells. Although the echidna erythrocytes had an abundance of 2,3-diphosphoglycerate and other glycolytic intermediates, no other energy-rich pyridine and purine compounds were detected.

https://science.sciencemag.org/content/sci/213/4515/1517.full.pdf

Hyun Dju Kim

Papers

NMR study of in vivo RIF-1 tumors: Analysis of perchloric acid extracts and identification of 1H, 31P and 13C resonances

Preferential hemolysis of postnatal calf red cells induced by internal alkalinization.

Pig reticulocytes. IV. In vitro maturation of naturally occurring reticulocytes with permeability loss to glucose

Adenosine triphosphate-deficient erythrocytes of the egg-laying mammal, echidna (tachyglossus aculeatus)

Erythrocyte phosphate composition and osmotic fragility in the Australian lungfish, Neoceratodus fosteri, and osteoglossid, Scleropages schneichardti