Physiological chemistry and physics最新文献

Common safe physiological agents such as diuretics, hormones, and oral lipids can increase differences in NMR parameters between uninvolved breast tissue in tumor bearing animals and mammary carcinomas. The differential response of the normal tissue to such agents, and the relative unresponsiveness of tumors, increased NMR distinction by as much as 250%.

Horse muscle acylphosphatase antibodies were obtained by immunizing rabbits with the highly purified antigen cross-linked with glutaraldehyde. Specific antibodies were purified from the immunoglobulin fraction by affinity chromatography using a matrix coupled with the pure antigen as immunoadsorbent. The purified antibodies were partially characterized by immunodiffusion and immunoprecipitin techniques. These antibodies could be used to study aspects of the muscle acylphosphatase structure, localization and other biological properties.

It was previously shown that human lymphocytes maintain a normal accumulation of K+ and exclusion of Na+ between 37 degrees and 10 degrees C., and a significant net accumulation of K+ and exclusion of Na+ at even lower temperatures. The studies reported here show that the level of ATP is near-normal for at least 24 hours between 37 degrees and 10 degrees C., but that ATP synthesis and utilization are progressively and markedly decreased with decreasing temperatures below 37 degrees C. The activities of the membrane Na+- and K+-activated ATPases have typical marked temperature-dependences. Therefore, the normal accumulation of K+ and exclusion of Na+ between 37 degrees and 10 degrees C., and the normal rate of Na+ efflux at these temperatures, do not correlate with properties of the Na+,K+-ATPase or with rates of synthesis and utilization of ATP.

Tyrosine aminotransferase from guinea pig liver spontaneously inactivates both in crude homogenates and in tissue slices. In the course of inactivation the cytosolic enzyme progressively translocates only into the microsomal fraction under an inactive form. Translocated enzyme activity can be restored by dithiothreitol addition which also produces the release of the enzyme from the microsomal particles. The specific binding of tyrosine aminotransferase to microsomal particles as a critical event for subsequent proteolytic degradation of the enzyme is postulated.

A weak point of the current concept of the kinetics of ion flow in complex epithelial tissue membranes, such as frog skin, is the supposition that these tissue membranes and their exterior environments can be looked upon as a "three compartment system." In the present study a new and more realistic conceptual framework, a "multicompartment system," is applied to a computer assisted kinetic analysis of experimental data. These deal with Na+ flows in "tight" and "leaky" frog skins, prior to and after the treatment with the Na+-blocking drug amiloride. It is shown by numerical examples that unpredictable Na+ flux patterns in frog skin arise from two diverse contributing factors: 1) The constitutive physical relationships which govern the local events at the level of the plasma membranes, and 2) the much neglected topology, i.e., the "connectedness" of the heterogeneous compartments.

Water proton spin-lattice relaxation times (T1) were measured in nuclear fractions from liver, kidney, and spleen tissues from normal and tumor-bearing animals (TBA) at two frequencies. At 9 MHz, the T1 values for TBA nuclear fractions are less than those for normal nuclear fractions, contrary to observations at the cellular level. Trace metal ion concentration and nucleic acid content estimated for these nuclear fractions suggest that the DNA-metal ion interaction might be responsible for the observed differences in the T1 of nuclear fractions at low frequencies.

Metallothionein inhibited in a concentration-dependent fashion the reduction of nitroblue tetrazolium [NBT] mediated by xanthine oxidase and by NADH-phenazine methosulfate. This catalytic activity of metallothionein for dismutation of O2- is dependent on the copper content in metallothionein.

Mice fed a sorbitol-enriched diet show measurable increases of alkaline phosphatase, glucose-6-phosphatase, and glucose-6-phosphate in the liver. The increases are positively correlated with duration of the sorbitol feeding program. The results could imply that sorbitol promotes glycogen synthesis.