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At least 307 records · Page 17Linked to original sources
PubMed1976

Biological ion exchanger resins. X. The cytotonus hypothesis: biological contractility and the total regulation of cellular physiology through quantitative control of cell water.

Actin-like (A-L) fraction from normal E. coli was compared with the protein from a potassium-transport mutant strain, and the cell-swelling reaction of both strains was studied. Findings were: (a) The membrane fraction of the mutant by SDS electrophoresis is deficient in the A-L fragment relative to normal whereas the soluble supernatant contains an excess. (b) Important catalytic differences exist between the A-L fractions of the two strains. The parent strain accumulates potassium in low K+ and the A-L fraction polymerizes in low K+. But the A-L fraction from the mutant fails to polymerize in low K media in the K+ concentration region where the mutant fails at K+ uptake. (c) The parent cell swells during low K+ uptake whereas the mutant does not. It is constructed from this that the differences in the characterization of A-L fraction relative to normal are related to the loss of cell-swelling in the mutant and hence to the loss in alkali cation selectivity. Thus two physical mechanisms, one macroscopic and dependent on the Gregor relation for swelling equilibria in ion exchange resins, and one more microscopic based on the dielectric dependence of the coulomb force between ion pairs, could underly regulation of ion selectivity by cell swelling. A similar proposal is made for the regulation of electron transport and oxidative phosphorylation in mitochondria. These findings and interpretations justify a new hypothesis to the effect that cell hydration is regulated by contractile proteins. The hypothesis fits together important observations hitherto unexplained, to wit: (1) The "missing link" as to the role of intermediate metabolism in biological ion exchange. (2) The swelling of bacterial protoplasts and its relation to (Mg2 + Ca2+)ATPase activity. (3) The swelling-contraction cycles of mitochondria and their role in electron transport. (4) The role of ATPase's in transport. (5) The significance of actomyosin fibers in nerve endings. (6) The significance of altered actomyosin structures in the cancerous cell.

Actins↗
PubMed2000

Improved detection limits and unbiased selectivity coefficients obtained by using ion-exchange resins in the inner reference solution of ion-selective polymeric membrane electrodes

By using a high concentration of an interfering ion and a low one of the primary ion in the inner reference solution of polymeric membrane ion-selective electrodes (ISEs), the lower detection limit may be improved and unbiased thermodynamic selectivity coefficients may be obtained. To this purpose, a cation-exchange resin is used here to keep the low concentration of the primary cation constant. Different compositions of the internal solution are required for obtaining optimal lower detection limits and unbiased selectivity coefficients. All ISEs studied here, i.e., for K+, Ca2+, and NH4+, based on valinomycin, ETH 5234, and nonactin/monactin, respectively, show improved lower detection limits in the range of 10(-7.6) (NH4+) to 10(-8.8) M (Ca2+). Nernstian responses and, therefore, unbiased selectivity coefficients are obtained with the K+-ISE for the discriminated ions, Na+, Mg2+, and Ca2+.

Journal Article↗
PubMed1978

Lead-loaded ion-exchange resin bead as a calcergen.

Several heavy metals have direct calcifying effects in connective tissues; most notable among them is lead (Pb), whether administered topically (1) or systemically with local injury (2). The mechanisms of metal-induced soft tissue calcification have been studied by injecting salts of known in vitro calcifying potential into subcutaneous connective tissue (3); of the metals used, only lead and holmium produced an early accumulation of minerals on collagen in vivo. Lead is also claimed to accelerate bone healing in the rabbit leg with no toxic effects (4). Lead-loaded ion-exchange resin beads, implanted into surgically prepared subcutaneous pouches in rats, rapidly induced subcutaneous calcification which has been studied by microradiography and electron-probe microanalysis.

Animals↗
PubMed1977

[Hypercalcaemic crises in patients with chronic renal failure caused by ion-exchange resins, antacidotics and other calcium-containing drugs (author's transl)].

Between 1972 and 1976 15 patients with chronic renal failure of different aetiology and varying severity were observed who developed 23 hypercalcaemic phases during treatment with calcium-containing drugs. 12 instances of hypercalcaemia occurred during conservative treated during conservative treatment (serum creatinine 177-1061 mumol/l, equivalent to 20-120 mg/l) and 11 during chronic haemodialysis (serum creatinine 707-1061 mumol/l, equivalent to 80-120 mg/l). In 15 cases hypercalcaemia was caused by a hexacalciumhexasodium-heptacitratehydrate complex (Acetolyt), in 6 cases by the combined use of this drug with calcium ion-exchange resins on a calciumpolystyrolsulfonate base, and in two cases by the use of calcium tablets and calciumpolystyrolsulfonate, respectively. The daily doses of these drugs were in the usual therapeutic range in most cases. Deterioration of renal function was observed in two cases and coma in a further two cases. In 5 cases gastric ulcers were demonstrated. Three patients died. In no patient was there evidence of florid hyperparathyroidism. Treatment with calcium-containing drugs in patients with renal failure should only be carried out under regular control of calcium concentrations.

Aged↗