A mechanism for action of extremely low frequency electromagnetic fields on biological systems.

This report outlines a simple mechanism, based on the Hall Effect, by which static and low frequency (50-60 Hz) pulsed electromagnetic fields (PEMFs) can modify cation flow across biological membranes and alter cell metabolism. We show that magnetic fields commonly found in the environment can be expected to cause biologically significant interactions between transported cations and basic domains of cation channel proteins. We calculate that these interactions generate forces of a magnitude similar to those created by normal transmembrane voltage changes known to gate cation channels. Thus PEMFs are shown to have the potential of regulating flow through cation channels, changing the steady state concentrations of cellular cations and thus the metabolic processes dependent on cation concentrations.

Long-term outcome of Lyme disease in children given early treatment.

Sixty-three patients treated with appropriate antimicrobial therapy between 1985 and 1990 for physician-documented erythema migrans were identified. A telephone interview program 1 to 6 years after the initial episode of Lyme disease revealed that none of the patients had evidence of carditis, arthritis, or neurologic complications attributable to Lyme disease. A new episode of erythema migrans was reported in 7 (11%) of the patients 1 to 4 years after the initial episode.

Vaginal opening measurement in prepubertal girls.

Normative, age-indexed data regarding the size of the vaginal opening in prepubertal girls have not been previously reported, to our knowledge. Measurement of the apparent transverse diameter of the vaginal opening was done in 273 prepubertal girls as part of their routine health assessment. Vaginal opening diameter tended to enlarge with age and to be larger in the supine knee-chest position than in the supine frog-leg position. An opening greater than 4 mm was distinctly rare.

Localization of calcium in roots and microsomal membranes of corn by direct pyroantimonate precipitation.

Many cell membrane systems, including microsomal vesicles of corn, are able to regulate calcium levels both in vivo and in vitro, often in an ATP-dependent, calmodulin-stimulated fashion. The purpose of this study was to determine calcium distribution in meristematic cells of intact tissue and microsomal vesicles from corn roots using direct pyroantimonate-osmium fixation. In root cells, precipitates were localized in mitochondria, plastids, the nucleus, endoplasmic reticulum, Golgi apparatus, and along the plasma membrane. Plasma membrane-enriched microsomal vesicles isolated from corn roots incubated in media to permit calcium transport before pyroantimonate-osmium fixation show internal precipitates associated with the membrane and in the lumen of the vesicles. De-staining of the sections with 1 mM EDTA or EGTA removed precipitate from the sections, confirming the presence of calcium in the antimonate precipitates. These data support biochemical data that this same membrane preparation exhibited ATP-dependent calcium sequestration that was stimulated by calmodulin, as measured by retention of 45Ca. This provides evidence that these membranes are responsible for ATP-requiring, calmodulin-stimulated calcium transport in the intact cell.

Characterization of nucleoside diphosphatase in the onion root tip. III. Solubilization and activation of membrane-bound enzyme(s).

UNLABELLED: The latency of nucleoside diphosphatase (NDPase) in onions root homogenates has been examined by comparing the activation of NDPase activity resulting from detergent treatment with that due to storage of homogenates for several days in the cold. Both detergent treatment and cold storage activated NDPase approximately two-fold. In both cases this activation was paralleled by the loss of enzyme activity from the membrane fractions and its appearance in the supernatants. Electrophoresis of these supernatants revealed an identifical isoenzyme pattern of 5 NDPase bands for both preparations. Enzyme kinetic studies demonstrated that NDPase from the detergent-treated homogenate and the homogenate stored in the cold as well as NDPase from the membrane and supernatant fractions from each of the homogenates all had the same Km value. These data suggest that latency of NDPase is the result of a breakdown of cellular membranes and subsequent release of NDPase. ABBREVIATIONS: DOC, deoxycholate; NDPase, nucleoside diphosphatase; IDP, inosine 5'-diphosphate; UDP, uridine 5'-diphosphate; GDP, guanosine 5'-diphosphate.

Glycosyltransferases in plant and animal tissues effects of fixation and lead on enzyme activity.

As the initial step toward the cytochemical localization of glycosyl-transferases in situ, biochemical determinations of these enzyme activities from onion root tips and L1210 cells were performed before and after fixation as well as in the presence of lead ions. Glycosyltransferase activity from roots fixed in buffered formaldehyde or glutaraldehyde before homogenization decreased as the concentration of the fixative or fixation time was increased. Formaldehyde fixation was less inhibitory than glutaraldehyde; 35% of the glycosyltransferase activity was retained after 30 min fixation in 2% formaldehyde while 25% of the enzyme activity remained after a similar fixation in glutaraldehyde. Substantially higher levels of L1210 cell glycosyltransferase activity were retained after a 30 min 2% formaldehyde fixation (60% sialyltransferase; 82% galactosyltransferase), but inhibition by glutaraldehyde was similar to that observed for onion root galactosyltransferase. Glycosyltransferase from formaldehyde-fixed roots was inhbited 35% by lead nitrate, but sialytransferase from formaldehyde-fixed L1210 cells was unaffected by lead ions. These findings are encouraging for further studies aimed at the development of cytochemical technique to localize glycosyltransferase in plant and animal tissues.

Nucleoside diphosphatase in the onion root tip. II. The effect of inhibitors on isoenzymes.

An electrophoretic study was performed to determine the number of isoenzymes of nucleoside diphosphatase in onion root extract. Five bands exhibiting nucleoside diphosphatase activity were detected when gels were incubated with inosine diphosphate, uridine diphosphate, guanosine diphosphate or cytidine diphosphate as substrates. These consisted of a single fast migrating band (band one), a group of three intermediate migrating bands (bands two, three and four) and a single slow migrating band (band five). Gels incubated with adenosine diphosphate, thiamine pyrophosphate, inosine monophosphate, guanosine monophosphate and cytidine monophosphate showed only two bands (bands one and five). Inhibitor studies showed that sodium fluoride inhibited bands one and five but not bands two, three and four. Conversely, 1% (v/v) glutaraldehyde inhibited bands two, three and four but did not inhibit bands one and five. These results suggest that two separate groups of onion nucleoside diphosphatase isoenzymes occur which have different substrate specificities and are selected against by certain inhibitors.

The interaction of cationic liposomes containing entrapped horseradish peroxidase with cells in culture.

Cationic liposomes composed of sphingomyelin, cholesterol, and stearylamine were prepared with horseradish peroxidase trapped inside. Stable particles were formed in which 10-12% of the enzymic activity appeared to be located at, or near, the outer surface of the liposome. Adsorption and uptake of liposomes by HeLa cells were followed cytochemically by electron microscopy and quantitated by enzyme assay and by the distribution and fate of particles labeled with [(14)C]cholesterol and [(125)I]horseradish peroxidase. The particles were adsorbed by HeLa cells at least 300 times as efficiently as was free horseradish peroxidase. Many of the particles remained at the cell surface, but numerous membrane-bound cytoplasmic inclusions were observed to contain peroxidase-staining material. In addition, many areas of the cell membrane gave a positive staining reaction. It was concluded that many particles (presumably the larger ones) did not gain access to the interior of the cells, many were phagocytized, and some enzyme was transferred to the cell membrane, perhaps as a result of fusion of the liposomal membrane with the cell membrane.