ABSTRACT
The Na,K-ATPase activity of erythrocyte membranes is markedly increased in normal-renin essential hypertensives. A temporal shift of the chronobiology of the erythrocyte-membrane-bound Na,K-ATPase in these patients is described. The disorder causes a loss of synchronism between the circadian rhythms of aldosterone and Na,K-ATPase. Such uncoupling phenomenon may explain the inversion of the day/night sodium excretion ratio and other disturbances of sodium metabolism found in essential hypertensives.
Subject(s)
Aldosterone/blood , Circadian Rhythm , Erythrocyte Membrane/enzymology , Hypertension/blood , Renin/blood , Sodium-Potassium-Exchanging ATPase/blood , Adolescent , Adult , Aldosterone/urine , Female , Humans , Hypertension/enzymology , Hypertension/urine , Male , Posture , Potassium/urine , Reference Values , Sodium/urineABSTRACT
The interaction between the carbohydrate and the amino acid residues in human thyroglobulin has been studied. Previous reports showed that the removal of the two terminal carbohydrates of the complex chains leads to an increase in thyroglobulin binding to thyroid membranes. In our study, after enzymatic release with glycosidases of the sugar moieties from thyroglobulin, a time-dependent decrease in tryptophan fluorescence has been observed. This decrease was also associated with a shift in the emission peak from 335 to 340 nm. The strong quenching of tryptophan emission was also accompanied by a decrease in the exposure of tryptophan residues, as shown by a Stern-Volmer analysis with the neutral quencher acrylamide. These data, together with the increase in fluorescence of the dansylated deglycosylated thyroglobulin, strongly suggest that a significant conformational change of thyroglobulin follows the deglycosylation of the protein.
Subject(s)
Glycoproteins/metabolism , Thyroglobulin/metabolism , Apoproteins/metabolism , Centrifugation , Humans , In Vitro Techniques , Protein Conformation , Spectrometry, Fluorescence , Structure-Activity Relationship , TryptophanABSTRACT
A good correlation was found between in vivo and in vitro responses of peripheral MNC from breast cancer patients and the NK boosting effect of human beta IFN. In vitro immunochemistry studies showed that marked antitumor effects were obtained against cultured cancer cells when a widely used chemotherapeutic agent such as 5-FU was combined with nonsensitized spontaneously cytolytic MNC, preactivated in vitro with beta IFN. These results suggest that the in vitro susceptibility assay of MNC to IFNs could be used for predicting favorable responses to immunochemotherapy regimens employing IFNs as immunomodulating agents.
Subject(s)
Interferon Type I/pharmacology , Killer Cells, Natural/drug effects , Neoplasms/therapy , Cytotoxicity, Immunologic , Drug Synergism , Female , Fluorouracil/pharmacology , Humans , Immunotherapy , In Vitro Techniques , Interferon Type I/therapeutic use , Tumor Cells, Cultured/drug effectsABSTRACT
1. The effect of ouabain on the molecular properties of (Na+/K+)-ATPase has been studied in purified preparations of the enzyme, isolated from the microsomal fraction of outer red medulla of porcine kidney, according to a modification of the method described by Jorgensen. 2. Ouabain, a specific inhibitor of (Na+/K+)-ATPase, binds at the potassium site of the enzyme, thus generating an increase in its stability towards the common denaturing agents, such as exposure to different concentration of guanidinium chloride (GdmC1) or to acidic solutions.
