Mast cell and blood coagulation functions during prolonged noradrenaline administration

During the long term noradrenaline injection (0.56 microgram/kg/min-2 hours during six days) the number of connective tissue mast cells decreases in dogs. Mature cells disappears and the percentage of young forms increases. Marked degranulation develops. 5-10 cell groups and chains are formed. The increase of free heparin level and the activation of anticoagulant unit hemostasis correspond to these changes. It is due to mast cells discharge of biologically active heparin which is an unspecific adaptogen.     

Mitochondrial proteinases of the yeast Saccharomyces cerevisiae: electrophoretic detection, substrate specificity and sensitivity to inhibitors

The proteins of submitochondrial particles solubilized with 0.1% Triton X-100 were separated by polyacrylamide gel electrophoresis. Hydrolysis of several proteinase substrates was registered directly in the gel after completion of electrophoresis. According to the data obtained the inner mitochondrial membrane contains one or two enzymes which catalyze hydrolysis of cytochrome c as well as one or two enzymes splitting synthetic substrate of trypsin-like proteinases, e. g. N-alpha-benzoyl-L-arginine-p-nitroanilide (BAPA) and N-alpha-benzoyl-L-arginine-beta-naphthylamide (BANA). Submitochondrial particles were shown to catalyze hydrolysis of 3H-labelled cytochrome c. This activity is suppressed by the same inhibitors as the hydrolysis of mitochondrial translation products, i. e. phenyl-methylsulfonylfluoride, p-chloromercuribenzosulfonate, leupeptin and antipain. Presumably these two processes are catalyzed by the same enzyme localized in the inner mitochondrial membrane. Physiological functions of BAPA- and BANA-hydrolyzing enzyme(s) are still unclear.     

Structural organization of kinetoplast DNA and its compactization in a model system in vitro

Studies on compactization and decompactization of the genome are of great importance for elucidation of structural mechanisms taking part in the regulation of gene activity. Kinetoplast DNA (kpDNA) is a convenient model for studies of compactization processes. KpDNA represents unique structure ("network"), consisting of catenated circular molecules of two types: minicircles (900 b.p.) and maxicircles (40 000 b.p.). The compactization process of kpDNA in vitro caused by interaction with synthetic peptide-dansylhydraside trivaline was studied. It was shown that at the initial stages the hairpins are observed on minicircles as if triple rings are being organized. The formation of hairpin is probably favoured by the presence in the minicircles of bent DNA, a specific nucleotide sequence causing rigid bending of the DNA helix. The hairpin does not make contact with the neighbouring DNA segment to form a triple ring, because the sizes of minicircles are too small. The minicircles compactization is finished with a complete collapse of the minicircles with the formation of rod-like structures. The catenation causes branching of rod-like structures. As a result of their intermolecular interaction, the branched rod-like structures become thicker. The process is completed with formation of the compact network, its diameter being 3-6 times smaller compared to the initial one.     

Molecular forms of alpha-1-acid glycoprotein in human blood serum. Differences in levels of di-, tri-, and tetra-antennary N-linked carbohydrate chains]

alpha 1-Acid glycoprotein isolated from healthy individuals blood was separated on Con A-Sepharose into three fractions: non-bound (AGP-1, 84%, 43.5 kDa), Con A-bound (AGP-2, 14%, 41.3 kDa), and Con A-tightly bound (AGP-3, 2%, 39.6 kDa). Amino acid compositions of these fractions were similar but carbohydrate ones differed. HPLC analysis of 7-amino-4-methylcoumarin derivatives of the oligosaccharides in combination with their sequential exoglycosidase digestion showed that AGP-1, AGP-2, and AGP-3 have the same set of oligosaccharides and differ only by their proposition. A minor quantity of agalacto-oligosaccharides (with a terminal GlcNAc residue) was identified.     

Role of creatine phosphokinase in the energy supply of the pumping function of the heart]

The cardiac output of isolated working rat heart and left ventricular pressure were estimated in either almost complete inhibition of creatine kinase by iodoacetamide or predominant fall in adenine nucleotides (AdN) content induced by 2-deoxyglucose treatment. In the former case, a profound cardiac pump failure was observed despite almost normal levels of myocardial AdN and phosphocreatine. Those hearts could not maintain the aortic output at standard load due to lower LV systolic pressure, that was accompanied by increased minimal and maximal diastolic pressures by 5-7 mm Hg as well as by LV diastolic stiffness. As LV systolic pressure in those hearts was unchanged in retrogradely perfused and unloaded hearts it might be suggested that the cardiac pump failure was caused by the decreased LV distensibility. On the contrary, deoxyglucose treatment that resulted in 70% fall in the AdN content was accompanied by only moderate reduction of the cardiac output and insignificant changes in LV diastolic pressure and stiffness. The results suggested that creatine kinase plays a crucial role in the maintenance of normal myofibrillar compliance, which is necessary for cardiac filling and pump function.     

Different properties of two groups of orientation discriminators in the cat visual cortex

The properties of 149 neurons, divided into two groups, were investigated during acute experiments on immobilized cats. These consisted of "timers" (37%) in which latency of response and time taken for reaction to peak changed in an orientation range of not more than 10 msec. The remaining 63% consisted of "scanners" [2]. "Timers" reliably differed from "scanners" in their shorter latent periods, rising time of discharge rate, duration of response, and higher rate of impulsation at all orientations of the stimulus. "Scanners" display greater orientational tuning and "scan" much more frequently throughout the orientation range. The pattern of acuity of orientational tuning is counterphasic during response in neurons of these two groups, while the distribution of their preferred orientation is complementary in nature. Both timers and scanners were found in the orientation columns of the visual cortex on most occasions, with the latter predominating. Columns consisting of only timers or scanners were met with more seldom. The significance of the differences between the properties of the two groups of neurons in the visual cortex is discussed with a view to orientational discrimination.Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 18, No. 1, pp. 85–92, January–February, 1986.     

The sensitive period in the development of the human visual system

The human visual system is the most sensitive to the deprivation of the object vision up to the age of 7, when the amblyopia produced by congenital or traumatic cataract develops in all cases and is "relatively" sensitive during the period from 7 to 15 years, when probability of amblyopia development and its degree are determined by the age of cataract appearance and duration of its existence. Visual deprivation taking place after 15 years does not lead to ambliopy. The data on visual evoked potentials (VEP) obtained during stimulation of the ambyopic and the second, intact eye are used in discussion of the neurophysiological mechanisms of the unilateral visual deprivation and of informative importance of VEP.     

Orientation selectivity of visual cortical neurons at different stimulus intensities in cats

Orientation selectivity of 24 neurons in area 17 of the visual cortex at different intensities of test bars of light, flashing against a constant light background in the center of the receptive field, was investigated in acute experiments on immobilized cats. Five neurons were invariant in orientation tuning to stimulus intensity (contrast): Although the magnitude of the response and acuteness of orientation selectivity were modified, preferential orientation was unchanged. More than half of the cells studied (13) were classed as noninvariant, for their preferential orientation was significantly shifted by 22–90° with a change in contrast. Small shifts of the peak of orientation selectivity, not statistically significant, were observed for the other neurons. Invariant neurons, unlike noninvariant, were characterized by preferential horizontal and vertical orientation, a lower frequency of spontaneous and evoked discharges, and the more frequent presence of receptive fields of simple type. The mechanisms of the change of orientation selectivity during contrast variation and also the different use of the two types of cells in orientation detection operations are discussed.