Walter X. Balcavage

Growth stage dependent effects of electromagnetic fields on DNA synthesis of Jurkat cells

A 1.8 mT, bone healing, electromagnetic field (EMF) and power frequency EMFs of 0.1 and 0.4 mT significantly inhibit DNA synthesis in otherwise unstimulated Jurkat (E 6.1) cells. Inhibition is generally most prominent in cells from mid log phase growth. In complete medium the bone healing EMF inhibits [3H] thymidine uptake of the latter cells by almost 50% vs. 20–25% inhibition by 60 Hz fields. Cells in conditioned medium are even more sensitive to EMFs with inhibition up to ca. 60%. The effects of the 0.1 and 0.4 mT power frequency EMFs were very similar suggesting saturation at 0.1 mT or lower.

Reaction of malonaldehyde with mitochondrial membranes

Malonaldehyde formed by lipid oxidation is regarded as a main crosslinker in the formation of natural age pigment. To elucidate the mechanism of pigment formation the reaction of malonaldehyde with biomembranes using fluorescence spectroscopy has been studied. Rat liver mitochondrial ghosts or bovine serum albumin were reacted with malonaldehyde. In both cases two main fluorescence changes were observed: protein fluorescence decreased to 50% of its initial value in about two hours; aminoiminopropene fluorescence reached a maximum at a much slower rate. The kinetics support a two-step reaction hypothesis. First, malonaldehyde reacts with protein quenching its fluorescence. Next fluorescent interprotein aminoiminopropene (AIP) crosslinks are formed. The fluorescence lifetime value of the induced AIP fluorophore was shown to be similar to the lifetime of naturally occurring age pigment previously reported for mitochondrial ghosts prepared from aged animals (5.4 ns +/- 0.3 and 5.9 ns +/- 0.6, respectively).

Changes in mitochondrial DNA during aging

Mitochondrial DNA (mtDNA) was isolated from liver mitochondria of rats between 2 and 24 months of age. The mtDNA was purified by cesium chloride--ethidium bromide isopycnic density gradient centrifugation. In the gradients, in addition to the two expected bands of ethidium--DNA complex, there was observed a third, more dense band (d = 1.69 g/cm3). This novel band, rarely observed in preparations from younger animals, was present in most preparations from older animals. The latter was characterized using the diphenylamine assay(s) and ascertained to contain DNA and carbohydrate components. Agarose gel electrophoresis revealed the DNA of the novel band to have a migration identical to form I mtDNA. Digestion of the novel band with the restriction endonuclease Bam HI yielded products identical to those obtained upon treatment of form I mtDNA with Bam HI. The observation of mtDNA at a density of 1.69 g/cm3 indicates the presence, predominantly in older animals, of a subclass of mtDNA molecules with altered ethidium binding properties. The significance of this mtDNA and its position in the gradient is unclear at this time.

Mitochondrial alterations associated with avian reticuloendotheliosis virus (strain T) pathogenicity.

Abstract This report indicates that reticuloendotheliosis virus (REV) induces morphological, physical and enzymatic alterations in chick target organ mitochondria. Succinoxidase activity of infected mitochondria is decreased at 5 days post-REV-infection, but ADP:O ratios are unchanged. Calcium accumulation is decreased from 100 nMoles/mg of protein in controls to 50 nMoles/mg of protein in infected mitochondria. Mitochondria from infected tissue exhibit a buoyant density of 1.193 gm/cc, significantly greater than the buoyant density of 1.167 gm/cc for control mitochondria. Mitochondria isolated from REV-infected livers were effective in transmitting reticuloendotheliosis when inoculated intraperitoneally into day old chicks. Electron microscopy of tissue sections indicates that infected cell mitochondria are enlarged with a less dense matrix relative to controls. Purified mitochondria from infected livers contained up to 16 particles having the size and shape of unenveloped(naked) C-type RNA tumor virus.

Nanosecond fluorescence decay study of mitochondria and mitochondrial membranes

Summary The nanosecond fluorescence decay of the tryptophan residues of rat liver mitochondria and mitochondrial membranes has been measured. Apparent fluroescence lifetimes of 3 to 11 nanoseconds have been observed. Authentic membrane proteins suspended in 50% DMSO exhibit fluorescence properties almost identical to membrane proteins in situ . It is found that the fluorescent membrane components appear to remain firmly bound to the membranes in fresh preparations, but can be, at least in part, released into the solvent phase as a consequence of freeze thaw procedures.

Reinstatement of Ovarian Cycles in Aged Female Rats by Placement of L-Dopa in the Medial Preoptic Area

Systemic treatment with the catecholamine precursor 1-dopa has been shown to reinstate ovarian cycles in the aged female rat (Quadri et al., 1973; Linnoila and Cooper, 1976). In an effort to determine if this effect is mediated via the action of 1-dopa on CNS catecholamines, we observed ovarian function after placing small amounts of 1-dopa directly into selected brain regions of aged rats (14 to 22 months old) bearing chronically implanted cannulae. Ovarian cycles could be reliably reinstated when 1-dopa was placed in the medial preoptic area of constant estrus or recurrently pseudopregnant females. This treatment was more effective (i.e. greater proportion of females responding.) and of longer duration (i.e. greater number of cycles observed) in 14–16 month old females than in the 22 month old females. Placement of 1-dopa in the septum, hippocampus or cortex had no effect on ovarian function. Placement of the norepinephrine precursor dlthreo-dihydroxyphenylserine (DOPS) or the neutral amino acid leucine in the four brain regions was without effect on ovarian function. The results will be discussed in terms of possible regional changes in brain amines with age.

Inhibitory effects of C-3 on membrane-associated enzymes.

Abstract It is reported here that 3,4,5-trimethoxybenzoyl-ϵ-aminocaproic acid (C-3) exhibits an inhibitory effect on adenylate cyclase, phosphodiesterase and mitochondrial ATPase. It is suggested that the mechanism of inhibition may be the same for the three enzymes; that is, a modification of the hydrophobic portion of the membrane region associated with these enzymes. The possible metabolic consequences of C-3 enzymic inhibition and its relation to the therapeutic use of this drug are also discussed.