Search PubMed⌕ Search

Biomedical subjects

M C Hardegree

Publications and source records attributed to M C Hardegree.

10 recordsLinked to original sources
PubMed1990

Transmembrane diffusion channels in Mycoplasma gallisepticum induced by tetanolysin.

The permeability properties of Mycoplasma gallisepticum cells treated with a purified preparation of tetanolysin were investigated by determining the initial swelling rates of cells suspended in an isoosmotic solution of electrolytes or nonelectrolytes. The swelling, initiated by the tetanolysin, depended on the tetanolysin concentration and was markedly affected by the molecular size of the various osmotic stabilizers utilized. Thus, the initial swelling rates in an isoosmotic solution of monosaccharides were much higher than those in isoosmotic solutions of di-, tri-, or tetrasaccharides. Cell swelling induced by tetanolysin was much lower with energy-depleted M. gallisepticum cells, with arsenate-treated cells, or when the membrane potential (delta psi) was collapsed by valinomycin (10 microM) plus KCl (100 mM). Swelling was not affected by the proton-conducting ionophore carbonyl cyanide-m-chlorophenylhydrazone (1 to 10 microM) or by nigericin (5 microM). These results support the concept that the damage induced by tetanolysin is due to the formation of water-filled pores within the membranes of energized M. gallisepticum cells. Such pores allow the diffusion of hydrophilic molecules into the cells and may vary in size, depending on the tetanolysin concentration utilized.

Cell Membrane↗
PubMed1985

Antibodies against the light chain of tetanus toxin in human sera.

Tetanus toxoid elicits protective antibodies against tetanus toxin in humans and animals. It has been reported that antitoxin from immunized humans contains no anti-light chain antibodies, based on immunodiffusion and quantitative precipitin analyses. We confirmed the absence of precipitating anti-light chain antibodies in tetanus immune globulin. However, the presence of antibodies against the light chain of the toxin was shown by direct binding and inhibition analyses, using enzyme-linked immunosorbent assays. Using a neutralization inhibition test, we also found that about one-fourth of the neutralizing antibodies in tetanus immune globulin are directed against the light chain. These results suggest that the light chain of tetanus toxin contains immunogenic determinants and that antibodies directed against it may have a role in the prevention of tetanus or treatment of tetanus or both.

Antibody Specificity↗
PubMed1979

Cholesterol-dependent tetanolysin damage to liposomes.

Tetanolysin caused membrane damage, resulting in release of trapped glucose from liposomes containing cholesterol. Maximum glucose release occurred from liposomes that contained 50 mol% cholesterol. At higher or lower levels of cholesterol, glucose release was reduced and glucose release did not occur at all below 40 mol% cholesterol. The apparent activity of tetanolysin was not influenced by temperature (24 degrees C compared to 32 degrees C) or by liposomal phospholipid fatty acyl chain length. We conclude that tetanolysin caused cholesterol-dependent lysin-mediated damage to liposomes, possibly by means of a pore consisting of a complex of toxin and cholesterol.

Bacterial Toxins↗
PubMed1979

Effect of tetanus toxin on the accumulation of the permeant lipophilic cation tetraphenylphosphonium by guinea pig brain synaptosomes.

Accumulation of the permeant lipophilic cation [(3)H]tetraphenylphosphonium (TPP(+)) by synaptosome preparations from guinea pig brain cerebral cortex is inhibited 1:10 by medium containing 193 mM K(+) and by veratridine. A further 1:10 to 1:15 decrease in TPP(+) uptake occurs under nitrogen and in the presence of mitochondrial inhibitors such as oligomycin, whereas starvation and succinate supplementation have no effect. These data indicate that, in analogy to intact neurons, there is an electrical potential (DeltaPsi, interior negative) of -60 to -80 mV across the synaptosomal membrane that is due primarily to a K(+) diffusion gradient (K(+) (in)-->K(+) (out)). The data also indicate that mitochondria entrapped within the synaptosome but not free mitochondria make a large contribution to the TPP(+) concentration gradients observed. Conditions are defined in which tetanus toxin binds specifically and immediately to synaptosomes in media used to measure TPP(+) uptake. Under these conditions tetanus toxin induces dose-dependent changes in TPP(+) uptake that are blocked by antitoxin and not mimicked by biologically inactivated toxin preparations. The effect of tetanus toxin on TPP(+) uptake is not evident in the presence of 193 mM K(+) or veratridine but remains under conditions known to abolish the mitochondrial DeltaPsi. Moreover, tetanus toxin has no effect on TPP(+) uptake by isolated synaptosomal mitochondria. The results thus define an in vitro action of tetanus toxin on the synaptosomal membrane that can be correlated with biological potency in vivo and is consistent with the in vivo effects of tetanus toxin on neuronal transmission.

Anaerobiosis↗
PubMed1978

Tetanus toxin interactions with the thyroid: decreased toxin binding to membranes from a thyroid tumor with a thyrotropin receptor defect and in vivo stimulation of thyroid function.

Normal rat thyroid membranes adsorb neurotoxicity when incubated with purified tetanus toxin. Membranes from a rat thyroid tumor with a thyrotropin receptor defect adsorb very little neurotoxicity when similarly evaluated. This inability of the tumor membranes to adsorb neurotoxicity is correlated with a defect in their ability to bind both 125I-labeled tetanus toxin and [125I]iodothyrotropin. The effect of tetanus toxin on the release of radioiodine from the thyroids of appropriately prepared mice has been measured by adapting methods used for the bioassay of thyrotropin. One minimum lethal dose of tetanus toxin given sc caused a significant release of radioiodine into the blood of mice 48 h after injection. In mice subjected to the stress of prior bleedings or anesthesia, the release of radioiodine from the thyroid by tetanus toxin was accelerated, i.e., the increase in blood radioiodine could be measured 24 h after injection. These results again suggest that tetanus toxin may interact with thyrotropin receptors on thyroid plasma membranes. The "sympathetic overactivity syndrome" seen in some patients with tetanus and the syndrome characterized as "thyroid storm" in patients with Graves' disease are discussed as they may relate to these observations.

Animals↗
PubMed1976

Interaction between tetanolysin and Mycoplasma cell membrane.

1. A partially purified tetanolysin preparation lysed the sterol-requiring Mycoplasma capricolum cells but had no effect on M. capricolum cells adapted to grow with no or very little cholesterol. The sterol-non-requiring Acholeplasma laidlawii cells grown either in a cholesterol-rich or a cholesterol-poor medium were unaffected by the tetanolysin preparation. 2. The lysis of M. capricolum cells by the tetanolysin preparation was temperature dependent, inhibited by cholesterol, sublytic concentrations of lucensomycin, and Mg2+. The sensitivity to lysis was greatly affected by the age of the culture, being highest in cells from the early logarithmic phase of growth and declining sharply thereafter. 3. Isolated M. capricolum membranes were capable of binding large amounts of the tetanolysin activity (up to 30 hemolytic units per mug membrane protein), 20 times as much as membranes of the adapted strain. The binding of tetanolysin activity to membranes was almost the same at 4,22, or 37 degrees C, and was very little affected by the age of the culture. The binding capacity of the membranes was not affected by the removal of 60-70% of membrane proteins by pronase digestion but markedly decreased with the removal of membrane lipids. 4. Of the five polypeptide bands detected in electrophorograms of the partially purified tetanolysin preparation, two bands (mol. wt. 44 000 and 42 000) were found to bind to the cholesterol-containing mycoplasma membrane preparation. EPR spectrometry revealed that the freedom of motion of fatty acid spin labels in the tetanolysin-treated membranes was markedly higher than that in untreated membranes. 5. The concept that tetanolysin interacts specifically with membrane cholesterol resulting in the shielding of cholesterol from its interaction with membrane phospholipids is discussed.

Acholeplasma laidlawii↗