Effect of alpha particles on bacteriophage T4

Exponential survival curves were obtained for a dry film culture of bacteriophage T4 Br+ after exposure to both alpha-particles and gamma-quanta. Relative biological effectiveness of alpha-particles was 4.68 with respect to survival. The mutation spectrum after alpha-irradiation slightly differed from that produced by gamma-radiation.     

Intralipid and free plasmatic tryptophan in vitro

In an attempt to investigate the role of the lipidic emulsion Intralipid in the development of metabolic encephalopathy in a patient showing high free tryptophan levels, the relationship between lipidic emulsion and free tryptophan was examined in in vitro experiments. The addition of intralipid to normal serum produces an immediate increase in non-esterified fatty acids and a parallel rise in free tryptophan. Moreover, when serum with intralipid is incubated at 37 degrees C, the lipases release new non-esterified fatty acids and the free tryptophan increases proportionally. The non-esterified fatty acid content of intralipid was found to be 12 +/- 2 mEq X 1(-1). An inverse correlation was seen between free tryptophan and different serum albumin concentrations. It is concluded that intralipid causes an increase in free tryptophan levels. It is known that in vivo free tryptophan modulates 5-hydroxytryptamine synthesis and thus may be considered a possible causal agent for encephalopathy.     

Immunohistology on formol-sublimate fixed and paraplast embedded kidney tissue with comparison to formalin fixation and to pre-embedding immunofluorescent staining

Many alternative methods for immunopathological evaluation of kidney tissue are now available. Immunofluorescent or immunoperoxidase staining of kidney can be performed after formalin fixation and paraffin embedding. This is also possible after fixation with formol-sublimate (Stieve's fluid) using the immunoperoxidase technique or by immunofluorescence after removal of mercury. Reduction of strong nonspecific fluorescence caused by the mercury fixative parallels the elimination of mercury as verified by X-ray microanalysis of the sections. Using a mouse model with injection of graded dilutions of antiglomerular basement membrane antibodies, immunofluorescent staining after Stieve fixation and embedding in Paraplast was about 60% of that in cryostat sections. Immunofluorescent staining after mercury removal can be followed by silver staining for detailed morphologic study of the same 1 micron Paraplast sections. A case of antiglomerular basement membrane glomerulonephritis is illustrated in more detail to show the necessity of alternative methods, including the technique presented, pre-embedding immunofluorescent staining of Epon sections, and electron microscopy, to make a reliable diagnosis of this disease.     

High mutagenic potency of several polycyclic aromatic hydrocarbons induced by liver postmitochondrial fractions from control and xenobiotic-treated immature carp

The metabolism of carcinogens in fish was examined by measuring the activation of different polycyclic aromatic hydrocarbons (PAH) by carp (Cyprinus carpio L.) liver post-mitochondrial fractions (S9) using the Salmonella typhimurium TA100 reverse mutation assay. For this study, 1 non-carcinogen, anthracene (AN), and 4 carcinogens, chrysene (CHR), benzo[a]pyrene (BaP), 3-methylcholanthrene (3MC) and 7,12-dimethylbenzanthracene (DMBA), were chosen. The bioactivating potency of the metabolic systems of carp pretreated with phenobarbital (PB), 3MC or Aroclor 1254 (ARO) were compared to uninduced carp liver. The results show that carp liver has the ability to metabolize carcinogenic PAH into mutagenic metabolites, which is enhanced when carp are pretreated with 3MC or ARO, but not with PB. A positive correlation between the induction of aryl hydrocarbon hydroxylase (AHH) activity in carp liver and the mutagenic potencies of CHR, BaP, DMBA and 3MC, has been observed. The bioactivating ability of carp liver S9 was compared with the ability of the same fractions from female Wistar rats (this study) as well as from Sprague-Dawley rats (literature data). When the mutagenic potencies of selected PAH had been normalized on the activity of BaP, the following order of mutagenic activities with S9 fractions from ARO-treated animals was obtained: (1) BaP (1) greater than DMBA (0.26) greater than 3MC (0.22) greater than CHR (0.05) greater than AN (0) for carp; (2) BaP (1) greater than 3MC (0.48) greater than CHR (0.31) greater than DMBA (0.16) greater than AN (0) for Sprague-Dawley rats; and (3) BaP (1) greater than 3MC (0.17) greater than DMBA (0.11) greater than CHR (0) = AN (0) for female Wistar rats. We conclude that carp and rats are very similar in their ability to activate carcinogenic PAH into mutagenic metabolites, which suggests that carp may be very susceptible to the carcinogenic activity of these compounds. According to our results from the mutagenicity study, as well as from the enzyme induction study, we propose the use of carp as a suitable model system for the study of chemical carcinogens.     

Structural changes in L-cell mitochondria exposed to cyanide

Using light and electron microscopy, as well as stereological analysis, a study was made of structural changes in mitochondria of cultured L-cells acted upon with 1 mM cyanide. After 23 hours of incubation, in cells cultured in the presence of cyanide the volume density of mitochondria, the volume of the average mitochondrion and the surface area of its membranes increased nearly twice as much. Concurrently, the number of mitochondria decrease also practically two-fold without any reliable changes in the surface area of membranes per unit of mitochondrion volume. A shorter (7 hours) incubation of L-cells in the presence of cyanide results in a decreased volume density of mitochondria in the cytoplasm, decreased volume of the average mitochondrion, without any significant changes in other above mentioned parameters. It is supposed that the changes in mitochondria under a prolonged cyanide treatment of cells are conditioned by the fusion of mitochondria as well as by a compensatory increase in the total surface of mitochondrial membranes.     

Peptide therapy of sleep disorders in neurotic rats

As a result of chronic stress, anxiety appeared in the rats behaviour, motor activity increased, heart rate quickened, blood pressure raised, conditioned instrumental alimentary reflexes missed, the duration of deep phases of sleep lowered, time of falling asleep became longer, the number of awakening increased. The change in quantitative characteristics of sleep was accompanied by its worsening, especially of rapid sleep. Administration of substance P (SP) eledoisin hexopeptide (EH) (250 mcg/kg), 100-200 mcg/kg of delta sleep peptide and 10 mcg/kg of ethylcrotyl barbiturate improved the rats behaviour and sleep parameters. Calipnon accelerated falling asleep. Delta sleep peptide increased sleep duration. SP and EH restored not only the quantitative characteristics of deep phases of sleep but greatly improved their quality: lowered the blood pressure disrupted tachycardia, normalized the conditioned activity.     

Asymmetry of movement direction as a tactic in the feeding behavior of rats

The sign and degree of spatial-motor asymmetry in rats were studied in conditions both of spontaneous or signalled choice in an U-maze and spontaneous multiple choice in a radial labyrinth. It was shown that during investigation of a new environment, motor asymmetry in rats was feebly expressed in all conditions of experiments, irrespective of the labyrinth scheme and experimental procedures. In the process of training, adequate behaviour was formed and in some conditions a distinctly expressed spatial asymmetry appeared, while in other cases it was absent. Apparently, while investigating an "unknown" situation (where rats can move rightwards and leftwards), the strategy of "displacement" is characteristic of them. Later the rate of asymmetry manifestation depends on concrete spatial and temporal characteristics of already "familiar" surroundings.     

Relationship between plasma volume reduction and plasma electrolyte changes after prolonged bicycle exercise, passive heating and diuretic dehydration

Plasma volume was decreased by prolonged bicycle exercise, by passive heating in warm water, by sauna dehydration, and by diuretically induced dehydration in eleven well trained subjects. Blood samples from an arm vein were taken before and after this pre-treatment, as well as after a subsequent standard exercise test (SET) on a bicycle ergometer (50%, 70% and 105% of max VO2; the SET with no pre-treatment was used as a control condition. The changes in plasma concentration of Na+, K+ and Cl- were not proportional to the calculated plasma volume changes. The Na+ and Cl- concentrations always increased in the plasma, while plasma potassium concentration was increased after prolonged exercise, but decreased after the other types of dehydrations. The standard exercise test produced a pronounced fall in total calculated plasma potassium and in K+ concentration measured 3-5 min after exercise in all types of experiments. In the standard exercise test the calculated water loss from the plasma volume was relatively large. It amounted to about 2/3 of the total water loss in the standard exercise test and was independent of the pre-treatments.     

Studies of protoplast fusion in Streptomyces chrysomallus

Conditions for the regeneration of cells from protoplasts of Streptomyces chrysomallus, a producer of the peptide antibiotic actinomycin, are described. Regeneration of fusion products was most efficient at 27-30 degrees C on regeneration R2 medium (Okanishi et al., 1974) containing 0.25 M-sucrose. The addition of phosphate (150-300 mg 1(-1) to the medium and incubation at 23 degrees C proved to be optimal for the regeneration of individual strains. Highest recombination frequencies after protoplast fusion were obtained by fusing protoplasts in the presence of 45% (w/v) polyethylene glycol 6000. With strains that produce no, or little antibiotic, protoplasts must be present in excess in fusion mixtures in order to overcome inhibition of regeneration by the antibiotic-producing partner.