The interaction of macrophages and bacteria: a comparative study of the induction of tumoricidal activity and of reactive nitrogen intermediates.

The abilities of various bacteria to induce in a pure population of bone marrow-derived mononuclear phagocytes (BMM phi) tumoricidal activity and/or the generation of reactive nitrogen intermediates (RNI) were comparatively assessed. Interaction of BMM phi with bacteria led to expression of these functional activities, indicating that the organisms were recognized as foreign. As the majority of bacteria elicited in BMM phi either tumoricidal activity (that is maintained for days) or the production of RNI, measured by the release of nitrite (that is short-lived), it appears that the two functions are under separate control.

Role of topology in bioenergetics of sodium transport in complex epithelia.

There has been some controversy as to whether in sodium-transporting epithelia (e.g., frog skin, toad urinary bladder) the Na-O2 ratio is independent of the net rate of transepithelial sodium transport or remains constant over a wide range of transport rates.

Compartmental analysis of the Na+ flux ratio with application to data on frog skin epidermis.

In this computer simulation study, the role of the topological factor on the Na+ influx/backflux (efflux) ratio in multicompartmental model membranes with active Na+ transport has been investigated. As in the classical "three compartment model", so also in multicompartment models with series order of compartments (series topology), the flux ratios are time-independent. By contrast, in models with series-parallel order of compartments (series-parallel topology), inclusive shunt pathways, the flux ratios are time-dependent.

Regulatory aspects of Na+ transport in complex epithelia (frog skin).

In the multilayered epithelial membranes, topological factors, in addition to factors operating in cell units, must be considered in the regulation of ion transport. One such factor, i.e.

Kinetic studies on the effects of ouabain on Na+ fluxes in frog skin.

Among 48 pieces of paired frog skins of Rana pipiens in Ringer's solution, 10 pieces showed a strictly monotone decrease in the short circuit current (SCC) following ouabain treatment (10(-4) M). In 9 cases a transient attenuation, and in 27 cases a distinct wave in the ebb of the SCC, was seen. In 2 instances, two waves were seen.

Topological aspects of ion transport in complex epithelia (frog skin).

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.

Network thermodynamic approach compartmental analysis. Na+ transients in frog skin.

We introduce a general network thermodynamic method for compartmental analysis which uses a compartmental model of sodium flows through frog skin as an illustrative example (Huf and Howell, 1974a). We use network thermodynamics (Mikulecky et al., 1977b) to formulate the problem, and a circuit simulation program (ASTEC 2, SPICE2, or PCAP) for computation.