Magnetic resonance study on the anatomical relationship between the posterior proximal region of the tibia and the popliteal artery.

Objective: To analyze and describe the distance from the popliteal artery to three specific areas of the proximal region of the tibia, with the knee extended, by means of magnetic resonance.

Methods: Images of 100 knees of patients who underwent magnetic resonance examinations were analyzed. The location of the popliteal artery was measured in three different areas of the posterior proximal region of the tibia.

FEMORAL ANTEVERSION AND THE NECK-SHAFT ANGLE: RELATIONSHIP WITH HIP OSTEOARTHRITIS.

Objective: To compare the existence of agreement between measurements of anteversion of the femoral neck and the degrees of osteoarthritis and abnormality of the neck-shaft angle in patients with unilateral idiopathic hip osteoarthritis, among three evaluators.

Methods: Forty-two patients with unilateral hip osteoarthritis were evaluated by means of simple radiography and computed tomography.

Results: It was observed that there was no significant variation in femoral anteversion between the diseased and healthy hips.

Outward potassium current oscillations in macrophage polykaryons: extracellular calcium entry and calcium-induced calcium release.

Outward current oscillations associated with transient membrane hyperpolarizations were induced in murine macrophage polykaryons by membrane depolarization in the absence of external Na+. Oscillations corresponded to a cyclic activation of Ca(2+)-dependent K+ currents (IKCa) probably correlated with variations in intracellular Ca2+ concentration. Addition of external Na+ (8 mM) immediately abolished the outward current oscillations, suggesting that the absence of the cation is necessary not only for their induction but also for their maintenance.

ATP- and UTP-induced currents in macrophages and macrophage polykaryons.

We have investigated the currents induced by extracellular ATP (ATPo), extra-cellular UTP, and other related compounds in macrophages. At potentials of -20 to -60 mV, a typical response to ATPo puffs consists of a fast-activating inward current followed by a transient outward current. The phenomenon lasts 5-20 s, but for sustained exposure to ATP the inward current persists for up to 10 min (our longest recording time).

Electrophysiology of phagocytic membranes: intracellular K+ activity and K+ equilibrium potential in macrophage polykaryons.

The role of K+ as current carrier during the slow membrane hyperpolarizations (SH) elicited by iontophoretic Ca2+ injections into macrophage polykaryons is studied. The intracellular K+ activity (ak) and the K+ equilibrium potential (Ek) are measured using ion-sensitive microelectrodes. The mean value of ak is 84 +/- 5 mM in a culture medium containing 5.

Reception-mediated phagocytosis of yeast by macrophage polykarions.

1. The phagocytic capacity of polynuclear macrophages (PNM) produced by intraperitoneal implants in mice was analyzed and compared with that of the mononuclear macrophage (M luminal diameter). The ability of PNM and M luminal diameter to interiorize aldehyde-fixed Saccharomyces cerevisiae is described.

Electrophysiology of phagocytic membranes. Role of divalent cations in membrane hyperpolarizations of macrophage polykaryons.

The electrophysiological properties of the membrane of mouse peritoneal macrophage polykaryons are studied. Slow hyperpolarizations can be elicited by iontophoretic injections of either Ca2+ or Sr2+ into the cytoplasm. The effect of both cations is identical, since: it is invariably triggered by the cation injection, the amplitude is dependent on the K+ gradient, quinine blocks reversibly the response to both cation injections.

Dual nature of the peaks of light scattered during spreading depression in chick retina.

In this work some physical properties of the optical concomitants of spreading depression (SD) are investigated in isolated chick retinas. The two peaks of light scattering during the phenomenon were studied at various wavelengths of the illuminating light. It was shown that the first fast increase in light scattering is highly dependent on the wavelength and seems to be a "blue" scattering.

Ca2+-sensitive K+ channels in phagocytic cell membranes.

In phagocytic cells evidence for properties of Ca2+-sensitive K+-selective channels comes mostly from electrophysiological studies. Macrophages and macrophage-like cells are compared with fibroblasts (L-cells) where the Ca+-dependent K+ conductance is better understood. This model shares a mesenchymal origin and an accessory phagocytic capacity with the professional phagocytes.

Electrophysiology of phagocytic membranes. III. Evidence for a calcium-dependent potassium permeability change during slow hyperpolarizations of activated macrophages.

The roles of potassium and calcium in the slow hyperpolarizations of membranes of activated macrophages are investigated using standard intracellular electrical recording techniques. The amplitude of spontaneous slow hyperpolarizations decreases as a logarithmic function of the external potassium concentration in the culture medium. Similar dependence on the potassium gradient is observed when different levels of membrane potentials are imposed by constant current injection.

Electrophysiology of phagocytic membranes. II. Membrane potential and induction of slow hyperpolarizations in activated macrophages.

The potential differences measured on the cell surface and after penetration into the cytoplasm of activated macrophages are described. Linear regressions are made of the measured potential differences as functions of the tip potential of each microelectrode. The surface potential of the macrophage is not significantly different from zero.

Electrophysiology of phagocytic membranes. I. Potassium-dependent slow membrane hyperpolarizations in mice macrophages.

Electrophysiological properties of activated mouse macrophages cultured in vitro were studied using microelectrode techniques. In a high percentage of the individual cells analysed a slow hyperpolarization (SH) was observed with a concomitant decrease (2--4 times) of the input resistance. Increasing doses of tetraethyl ammonium progressively reduce the amplitude of the SH and at a concentration of 15 mM complete blockade of the phenomena is observed.

On the fine structure of the electrocyte of Electrophorus electricus L.

The general ultrastructure of the electrocyte, the basic unit of the electric organs of Electrophorus electricus, is analyzed. Presented herein are detailed observations of the syncytial surface, its fibrillar coat, invaginations of the plasma membrane and synaptic terminals. Using Thiéry's method glycogen granules were identified in the syncytial cytoplasm and inside the synaptic terminals, their size and structure being compatible with the muscular origin of the electric organs, to which the filamentous meshwork found in the cytoplasm may be related.

Junctional membrane permeability : Effects of divalent cations.

Junctional membranes ofChironomus salivary gland cells were exposed to test media of varying divalent cation concentration through a hole (estimated diameter ∼10 μ) in a cell's nonjunctional surface membrane. Junctional conductance is markedly depressed by Ca(++), Mg(++), Sr(++), Ba(++) and Mn(++). The order of potency is Ca(++)>Mg(++)>Sr(++)>Ba(++); the minimal effective concentration for Ca is 4 to 8×10(-5) M.