Glomerulometric data in experimental toxicological investigations

Glomerulometric quantitative investigations from rat kidney during chronic attempt with the substances Deta-20 and Polystabil VZ on paraffin sections were carried out. These substances are utilized in textile and food industry. Data, obtained by means of a graduated eyepiece-micrometer for light microscope, were plotted on histograms. This work is an attempt to introduce lightoptical morphometric measurements for nuclei and cells as well as for other structures (glomeruli).     

Application of mechanotronic transducers in experimental biological investigations

Mechanotronic transducers applied usually in technical investigations for the measurement of displacements, tensions, pressures and other mechanical parameters have been studied to register the contractile activity of isolated organs (the frog heart ventricle, the rat ileum strips) and the blood pressure in anesthetized animals. It was found that the mechanotronic transducers are simple, convenient and reliable devices for such investigations.     

Immunohistochemical investigations of excitotoxicity in experimental spinal cord trauma

The concept of "excitotoxicity" assumes that high concentration of glutamate (main excitatory neuromediator) acting through specific receptors leads to damage of cells due to an influx of calcium ions. Proteins called "excitatory amino acid transporters" (EAATs), present in astroglia, play important role in the removal of glutamate. We investigated the expression of GluR2 (glutamate receptor), EAAT1, and EAAT2 by immunohistochemistry in formalin-fixed, paraffin-embedded rat spinal cords, previously subjected to experimental mechanical trauma. In the injured spinal cords, an elevated immunoreactivity of GluR2 was noted even 10 min after trauma and was still observed 2 days after injury. Strong immunoreactivity was observed not only in many cells in gray matter but also in some cells in white matter (probably glial cells). In the injured spinal cords, we observed stronger (as compared with controls) expression of EAATs in the white matter, especially 6 hours after injury. The results support the role of excitotoxicity in mechanical trauma of spinal cord suggesting a possibility of long lasting elevated expression of glutamate receptor. It may help to understand and to explain beneficial action of "anti-glutamate" drugs, reported by other investigators.     

Serologic and experimental investigations of contagious ecthyma in Alaska

Serologic evidence of contagious ecthyma (CE) was found in domestic sheep (Ovis aries), domestic goats (Capra hircus), Dall sheep (Ovis dalli), and musk-ox (Ovibos moschatus) in Alaska. A moose (Alces alces) calf and a caribou (Rangifer tarandus) fawn were susceptible to experimental infection and both developed antibody titers as a result. CE virus was isolated from lesions of Dall sheep which were involved in a natural outbreak of the disease.     

Physico-chemical characterization of Intralipid emulsions.

Fat emulsions containing soy triacylglycerols (100-300 g/l) and egg-yolk phospholipids (12 g/l) are often used for intravenous feeding. Previous studies have shown that these emulsions contain chylomicron-like emulsion particles of diameters of 300-400 nm and excess phospholipids aggregated as vesicles (liposomes), which remain in the infranatant upon floatation of the emulsion particles by ultracentrifugation. This work is devoted to the characterization of the commercial lipid emulsions commonly denoted Intralipids, with special emphasis on the presently ill-defined liposomes. The lipid particles composing commercial lipid emulsions (10%, 20% and 30% Intralipids, Kabivitrum Nutrition) were characterized by the combined use of physical and chemical methods. Each of the emulsions was fractionated by ultracentrifugation in saline into a 'cream' layer which floats to the top of the dispersion upon ultracentrifugation and a relatively transparent infranatant. The cream layer contains large emulsion particles of diameters ranging from 300 to 400 nm, in agreement with theoretical considerations based on their chemical composition as determined by chemical analysis. The infranatants contain about 1 g/l triacylglycerols in addition to phospholipids (from 7.2 g/l in 10% Intralipid to 2.4 g/l in 30% Intralipid) in the form of smaller particles of 70-100 nm diameter. Cryo-transmission electron microscopy shows that the infranatants contain vesicles (mostly unilamellar) at the side of residual small emulsion particles. This conclusion is also consistent with the distribution of phospholipids between outer and inner lamellae, as determined by 31P-NMR.     

Physico-chemical characterization of hamster interferon.

The glycoprotein nature of Syrian hamster interferon was tested on several immobilized lectins. The specific retention of a small portion (20%) of interferon activity was observed only on concanavalin A-agarose; Component I of the interferon (not retained) has an apparent molecular weight of 23,500 whereas Component II (retained) is larger, 31,500. The apparent hydrophobicity of Syrian hamster interferon was probed by its chromatography on: (a) straight chain hydrocarbons of varied length; (b) aromatic ligands (aminobenzene, benzylamine, beta-phenylethylamine, gamma-phenyl-propylamine); ligands listed in (a) and (b) were immobilized to cyanogen bromide-activated agarose (isourea linkage); and (c) phenyl-agarose (Phenyl-Sepharose CL-4B), an aromatic ligand immobilized via a 2-hydroxypropyl arm to the agarose (ether linkage).     

Physico-chemical analysis of Bordetella pertussis antigens.

Physico-chemical methods are being developed for use in the control and standardization of acellular pertussis vaccines and their individual components. We have compared native and detoxified preparations of the B. pertussis antigens, pertussis toxin (PT), filamentous haemagglutinin (FHA), and the 69-kDa outer membrane protein (P69) using circular dichroism (CD), fluorescence spectroscopy, SDS-PAGE and FPLC gel filtration chromatography. Upon aldehyde detoxification, PT underwent a large change in its intrinsic fluorescence maximum (8-10 nm red-shift) and a large increase in its apparent size, detected by chromatography. Polyacrylamide gels showed individual subunits of the same apparent molecular weight (M(r)) as well as some polypeptides of higher M(r). FHA also changed conformation (5-nm red-shift in intrinsic fluorescence) upon aldehyde detoxification, with a resultant increase in the M(r)of its major constituent. The P69 protein appeared quite robust to formaldehyde treatment as measured by the same methods. Its near-UV CD spectrum contains a prominent tryptophan band; so this method may be more suitable for observing differences in conformation. We also examined an aluminium-desorbed DTaP preparation by these methods. When used in conjunction with immunochemical and toxicological assays, these methods are informative and useful in the characterization of candidate standards and should be valuable methods for ensuring the consistency of manufactured vaccines.     

Ultrastructural and experimental investigations of sperm-egg interactions in fertilization ofHydra carnea

Summary Fertilization in the freshwater hydrozoanHydra carnea has been examined by light, scanning and transmission electron microscopy. Sperm penetrate the jelly coat which covers the entire egg surface only at the site of the emission of the polar bodies. The egg surface exhibits a small depression, the so called fertilization pit at this site. Sperm-egg fusion takes place only at the bottom of the fertilization pit.Hydra sperm lack a structurally distinct acrosome and in most of the observed cases, fusion was initiated by contact between the membrane of the lateral part of the sperm head and the egg surfacce. Neither microvilli nor a fertilization cone are formed at the site of gamete fusion. The process of membrane fusion takes only a few seconds and within 1 to 2 min sperm head and midpiece are incorporated in the egg.Electron dense material is released by the egg upon insemination but cortical granule exocytosis does not occur and a fertilization envelope is not formed. The possible polyspermy-preventing mechanisms in hydrozoans are discussed. Hydra eggs can be cut into halves whereupon the egg membranes reseal at the cut edges and the fragments assume a spherical shape. Fragments containing the female pronucleus can be inseminated and exhibit normal cleavage and development. The observation that in such isolated parts the jelly coat will not fuse along the cut edges was used to determine its role in site-specific gamete fusion. These experiments indicate that site-specificity of gamete fusion can be attributed to special membrane properties at the fertilization pit.     

Electromyographic investigations in torticollis.

In 13 patients with torticollis, the electromyographic (EMG) activity in the neck muscles at rest was investigated before, during and after stimulation of the H1 bundle (in horizontal torticollis) and inner part of oral ventral nucleus (in the rotatory form), as well as after coagulation. Three EMG types of torticollis-spasmodic, myoclonic and mixed - could be differentiated. During the 8-, 25- and 50-Hz stimulations, a diminution in the amplitude and frequency of muscle potentials, followed by electric silence, was most often obtained; in general, the electric silence was preceded by a rhythmic activity of grouped potentials. Following coagulation, no spontaneous EMG activity was any longer recorded in the neck muscles, in the majority of the cases.