Influence of innervation on molecular forms of acetylcholinesterase in regenerating fast and slow skeletal muscles.

Nerve-intact muscle regenerates were prepared by ischemic-toxic injury of slow soleus (SOL) and fast extensor digitorum longus (EDL) muscles of the rat. Rapid innervation of regenerating myotubes modified intrinsic patterns of AChE molecular forms, revealed by velocity sedimentation in linear sucrose gradients. Regarding their onset, the effects of innervation can be classified as early and late.

Ligation with T4 RNA ligase of an oligodeoxyribonucleotide to covalently-linked cross-sectional base-pair analogues of short, normal, and long dimensions.

Compounds that are covalent analogues of nucleic acid base pairs of normal, long, and short C1' to C1' dimensions [B. Devadas and N.J.

Induction of steroidal 11 beta-hydroxylase of Cochliobolus lunatus.

The induction of steroidal 11 beta-hydroxylase of Cochliobolus lunatus was studied and the effect of the structure of steroid inducers and additives on the extent of enzyme induction determined. 21-Hydroxyprogesterone was found to be the best inducer and Torlak peptone 1 the best additive. A certain parallelism was found between the induction of 11 beta-hydroxylase of Cochliobolus lunatus and 11 alpha-hydroxylase of Rhizopus nigricans.

A contribution to the mechanism of action of SAD-128.

SAD-128 was found to be an effective protector of acetylcholinesterase against inhibition by soman, due to its ability to function as a reversible inhibitor and allosteric modifier of the AChE active site. It also attenuated aging of the soman-inhibited enzyme. In order to study the connection between some of these effects of SAD-128 and structural changes in acetylcholinesterase and/or the membrane to which the enzyme is bound, the influences of SAD-128 on the EPR spectra of the spin labelled enzyme and of the membrane were studied under various conditions and the results correlated with the kinetic parameters.

The cytotoxic and cytolytic activity of equinatoxin II from the sea anemone Actinia equina.

The cytotoxic and cytolytic effects of equinatoxin II (EqT II) from the sea anemone Actinia equina L. were studied on exponentially growing and synchronized V-79-379 A cell line in culture. The cell viability test and the determination of the cytolytic effect by cell counting confirmed both cytotoxic and cytolytic activity of EqT II.

The mechanical behaviour of cell membranes as a possible physical origin of cell polarity.

The mechanical behaviour of a closed layered membrane enclosing a structureless interior is considered. The shape of such an object in flaccid conditions is determined theoretically by assuming that it corresponds to the minimum value of the membrane bending energy. The symmetry breaking properties of this system are revealed.

Vanadium determination at the ultra-trace level in biological reference materials and serum by radiochemical neutron activation analysis.

In order to help resolve present inconsistencies of two orders of magnitude or more in reported levels of vanadium in human serum and blood, a totally postirradiation radiochemical neutron activation analysis (NAA) method was further developed and applied to some pertinent nanogram and subnanogram reference materials. In particular, the second generation human serum reference material of Versieck was found to contain a value of 0.67 +/- 0.

Determination of trace elements in standard reference materials by the ko-standardization method.

The ko-standardization method is suitable for routine multielement determinations by reactor neutron activation analysis (NAA). Investigation of NIST standard reference materials SRM 1571 Orchard Leaves, SRM 1572 Citrus Leaves, and SRM 1573 Tomato Leaves showed the systematic error of 12 certified elements determined to be less than 8%. Thirty-four elements were determined in NIST proposed SRM 1515 Apple Leaves.

11 beta-hydroxylation of steroids by Cochliobolus lunatus.

The substrate specificity of 11 beta-hydroxylase of Cochliobolus lunatus was studied and a close parallelism to the results obtained with 11 alpha-hydroxylase of Rhizopus nigricans was observed. It was found that the cell wall does not differentiate between the steroid substrates used and the absence of the cell wall increases the bioconversion.

A modified method for the determination of methylmercury by gas chromatography.

A simple modification of the Westöö extraction procedure for methylmercury and its determination by gas chromatography (GC) is presented. The cysteine clean-up step has been modified, with use of cysteine-impregnated paper instead of cysteine solution. Methylmercury bromide is extracted from the sample into toluene and is selectively adsorbed on the cysteine paper.

Human skeletal muscle: phasic type of electrical stimulation increases its contractile speed.

Skeletal muscles, exposed to a prolonged period of specific functional demands, respond adaptively. Electrical stimulation, when employed as a technique for subjecting selected muscles to altered use, enables precise entrainment of the pattern of functional activity. In this investigation, the vastus lateralis muscle in a group of volunteers was stimulated.

New method for isolation of venom from the sea anemone Actinia cari. Purification and characterization of cytolytic toxins.

1. Venom from the sea anemone Actinia cari was obtained by the "milking" method. Two lethal and hemolytic polypeptide toxins, caritoxins I (CTX I) and II (CTX II), were isolated with gel and ion exchange chromatography.

Neurite-promoting influences of proliferating Schwann cells and target-tissues are not prerequisite for rapid axonal elongation after nerve crush.

An important role in peripheral nerve regeneration has been ascribed to humoral trophic and tropic agents arising from the nonneuronal cells in the distal nerve stump and the denervated targets. In order to estimate their contribution to axonal elongation after crush injury to the rat sciatic nerve, an in vivo model was designed in which local cellular and target-derived influences were eliminated by 1) freeze-thawing of a long nerve segment distal to the crush site and 2) cutting the nerve far distally to the crush site, but within the frozen-thawed segment, and deflecting the frozen-thawed nerve stump in the opposite direction from its natural course. The sensory and motor axon elongation rate was estimated from the results of the nerve pinch test and choline acetyltransferase distribution along the nerve segment distal to the crush.

Rapid growth of regenerating axons across the segments of sciatic nerve devoid of Schwann cells.

The characteristic response of Schwann cells (SC) accompanies peripheral nerve injury and regeneration. To elucidate their role, the question of whether or not regenerating axons can elongate across the segments of a peripheral nerve devoid of SC was investigated. Rat sciatic nerve was crushed so that the continuity of SC basal laminae was not interrupted.

Prolonged cultivation of rat uterine cells with preserved estrogen responsiveness.

A rat uterine cell culture was prepared as an experimental system for investigation of mechanisms of steroid hormone actions. Cells frequently supplemented with fresh medium were successfully cultured for 4 weeks through 2 successive passages. Studies of estrogen responsiveness in the primary culture as well as in it's first subculture were performed by a small scale uptake assay for determination of specific steroid binding.

The voltage-clamp apparatus assisted by a 'current pump'.

A current pump is described, which is attached to the last stage of the 2-microelectrode voltage-clamp apparatus. Thus a voltage-to-current conversion independent of the impedance of the current microelectrode is obtained. In this way it is possible to pass relatively large currents through the current microelectrode and in the same time to have a stable negative feed-back system.

Membrane bending energy and shape determination of phospholipid vesicles and red blood cells.

A procedure is developed to calculate red blood cell and phospholipid vesicle shapes within the bilayer couple model of the membrane. The membrane is assumed to consist of two laterally incompressible leaflets which are in close contact but unconnected. Shapes are determined by minimizing the membrane bending energy at a given volume of a cell (V), given average membrane area (A) and given difference of the areas of two leaflets (delta A).

Spin probe reduction in cells and tissues.

The reduction rates of different nitroxides in rat lung tissue were measured by electron paramagnetic resonance. We confirmed that the reduction rate of nitroxide spin probe molecules is coupled with their structure and transport characteristics. Oxygen was found to slow down the reduction rate of nitroxides in rat lung tissues.

Caries prevalence in 12-year-old children in Ljubljana in 1970 and 1985.

In Yugoslavia accurate data on the caries trend have not been available so far. In the present study, we have compared the caries status of 12-yr-old children in the years 1970 and 1985. Dental examinations in both surveys were carried out by the same examiner.

Water proton NMR relaxation mechanisms in lung tissue.

The NMR relaxation times T'2, T2, and T1 were measured in isolated rat lungs as functions of external magnetic field B0, temperature, and lung inflation. The observed linear dependence on B0 of the tissue-induced free induction decay rate (T'2)-1 provides independent confirmation of the air/water interface model of the lung. Furthermore, measurements of the Larmor frequency dependence of T1 are consistent with a spin-lattice relaxation rate of the form 1/T1 = A omega -1/2 + B as expected for the case in which the relaxation arises from water-biopolymer cross-relaxation, which should be proportional to the surface area of the lung.

Two types of focal accumulations of acetylcholinesterase appear in noninnervated regenerating skeletal muscles of the rat.

Muscle fibers in the soleus muscle of the rat, injured by bupivacaine and free autografting, were allowed to regenerate within their old basal laminae. Histochemical and cytochemical analysis of newly synthesized acetylcholinesterase (AChE) revealed that two kinds of focal accumulations of AChE appeared in regenerating myotubes. First, AChE gets concentrated at the sites of the former motor endplates.

Cysteine proteinase inhibitors in inflamed human gingiva.

In the present work we demonstrate the presence of cysteine proteinase inhibitors of all three classes: kininogens, stefin A, and cystatin C, in inflamed human gingiva. Using cystatin C, in inflamed human gingiva. Using immunochemical methods we found that stefin A is the major inhibitor of cysteine proteinases, followed by kininogen and cystatin C.