Study on Conformational Changes in Hemoglobin Protoporphyrin in Essential Hypertension

Changes in protoporphyrin conformation, partial pressures of O₂ and CO₂, and the mechanisms responsible for regulation of pCa and pH in erythrocytes were studied in essential hypertension (EH). Changes in protoporphyrin conformation in EH were accompanied by a decrease in the partial pressure of O₂ and an increase in the partial pressure of CO₂. This was associated with increased activities of Na⁺/H⁺-exchange and Ca²⁺-dependent K⁺-channels and with a decreased activity of Ca²⁺-ATPase. The changes in protoporphyrin conformation in EH are suggested to decrease the efficiency of O₂ metabolism in hemoglobin and increase the values of intracellular pCa and pH of erythrocytes.     

Role of the Plasmalemma in Controlling the Gravitropic Response of Wheat Coleoptiles

The changes in the specific binding of ³H-IAA to the plasmalemma from segments of wheat (Triticum aestivumL.) coleoptiles and the physiological activity of the IAA–protein complexes thus formed in dependence on the duration of gravitational stimulation (GS) (1 g) were studied. The overall inhibition of the formation of IAA–protein complexes was accompanied by a transverse polarization of their functional activity occurring as early as within two minutes after the onset of GS. The pretreatment of plasmalemmal vesicles with 0.1 M CaCl₂prevented the in vitroIAA–protein complex formation in the plasmalemma. It is suggested that the GS results in an increase in the plasmalemma permeability for Ca²⁺, which reduces the capacity of the plasmalemma to bind IAA at the early stages of the gravitropic response.     

Physiological and Morphological Specific Features of the Formation of the Thyroid Status in the Aboriginal and Migrant Populations of Magadan Oblast

Ultrasonographic determinations of the thyroid gland volumes and measurement of the blood plasma content of thyroxin and triiodothyronine were carried out in 1176 apparently healthy residents of the Magadan oblast, all those examined being divided by sex, age, and the adaptation time in the North. Special attention was given to the thyroid system parameters of the aborigines 17 to 40 years old living in the urban area and not involved in the traditional life style. The indigenous population of the Extreme North and migrants were shown to have marked functional adaptive hyperplasia of the thyroid gland and diffuse goiter in 15% of cases. The size of the thyroid gland and the level of the thyroid hormones in the aboriginal population are within the average European range. Diffuse goiter manifestations in males virtually do not occur; in women, the incidence does not exceed 5%. The assumption is advanced as to the formation in aborigines of the northern hypothyroid phenotype providing for the sustained optimal level of the thyroid system functioning without an increase in the thyroid volume.     

Role of Ca2+ in regulating the serotonin-dependent synapse between P and R-cells of leech segmented ganglion]

Changes in the membrane-associated Ca2+ concentration and viscosity of the plasmatic membrane of P- and R-cells segmented ganglia of medicinal leech upon a variation of extracellular serotonin concentration were investigated. It is shown that the transmission of rhythmic excitation from P- to R-cells is due to the formation of the serotonin-dependent synapse and affects the distribution of the membrane-associated Ca2+ and intracellular processes controlling the viscosity of the membrane.     

β-structure of the coat protein subunits in spherical particles generated by tobacco mosaic virus thermal denaturation

Conversion of the rod-like tobacco mosaic virus (TMV) virions into “ball-like particles” by thermal denaturation at 90–98?°C had been described by R.G. Hart in 1956. We have reported recently that spherical particles (SPs) generated by thermal denaturation of TMV at 94–98?°C were highly stable, RNA-free, and water-insoluble. The SPs were uniform in shape but varied widely in size (53–800?nm), which depended on the virus concentration. Here, we describe some structural characteristics of SPs using circular dichroism, fluorescence spectroscopy, and Raman spectroscopy. It was found that the structure of SPs protein differs strongly from that of the native TMV and is characterized by coat protein subunits transition from mainly (about 50%) α-helical structure to a structure with low content of α-helices and a significant fraction of β-sheets. The SPs demonstrate strong reaction with thioflavin T suggesting the formation of amyloid-like structures.     

The cardiac hormonal system as a link in hemodynamic regulation and water-salt homeostasis

Classic and modern data on natriuretic peptide hormones that are synthesized in cardiac atria and participate in hemodynamic and water-salt balance regulation are summarized in this paper. Cumulated data on polypeptide variety, their structure, intracellular syntheses, physiological effects and concentration alterations during model experiments and cardiovascular pathology are presented. Unsolved problems including methods of plasma peptides concentration measurements, their role in heart failure development, and their clinical significance are discussed.     

Salicylic and Jasmonic acids in regulation of the proantioxidant state in wheat leaves infected by <Emphasis Type="Italic">Septoria nodorum</Emphasis> Berk

Influence of mediators of the signal systems of salicylic (SA) and jasmonic (JA) acids and their mixture on reactive oxygen species’ (ROS) (superoxide radical and O₂^·− H₂O₂) generation and activity of oxidoreductases (oxalate oxidase, peroxidase and catalase) in leaves of wheat Triticum aestivum L. infected by Septoria leaf blotch pathogen Septoria nodorum Berk has been studied. Presowing treatment of seeds by SA and JA decreased the development rate of fungus on wheat leaves. SA provided earlier inductive effect on production of O₂^·− and H₂O₂ compared with JA. The protective effect of the salicylic and jasmonic acids against Septoria leaf blotch pathogen was caused by activation of oxalate oxidase, induction of anion and cation peroxidases, and decrease of catalase activity. Ability of compounds to stimulate ROS in the plant tissues can be used as criteria for evaluation of immune-modulating activity of new substances for protection of the plants.     

The Relation of Different-Scale Membrane Processes Under Nitric Oxide Influence

Rhythmic activity, synaptic transmission and propagation of excitation depend on the processes that occur at different cellular levels. Modulation of neuron activity results from the changes of plasma membrane and organelles properties. We aimed to study the relationship between changes of the ion channels activity, membrane microviscosity and amount of bound Ca²⁺ under the influence of nitric oxide (NO). We also investigated the effect of NO on the refractive index of neurons. We have shown that NO activates voltage-dependent K(K_V)-channels and leads to the decrease in the amount of membrane-bound and stored Ca²⁺. NO causes a decrease in the microviscosity of the membrane of cytosomes and altered refractive index of neurones. The latter can result from the modification of plasma membrane physico-chemical properties and structural changes in the cytoplasm (vesicles movement, reorganisation of cytoskeleton, etc.). It is suggested that long-term modifications of the physico-chemical properties of membranes and reorganisation in the cytoplasm affect neuron activity and signal transmission.     

Mapping of redox state of mitochondrial cytochromes in live cardiomyocytes using Raman microspectroscopy

This paper presents a nonivasive approach to study redox state of reduced cytochromes [Formula: see text], [Formula: see text] and [Formula: see text] of complexes II and III in mitochondria of live cardiomyocytes by means of Raman microspectroscopy. For the first time with the proposed approach we perform studies of rod- and round-shaped cardiomyocytes, representing different morphological and functional states. Raman mapping and cluster analysis reveal that these cardiomyocytes differ in the amounts of reduced cytochromes [Formula: see text], [Formula: see text] and [Formula: see text]. The rod-shaped cardiomyocytes possess uneven distribution of reduced cytochromes [Formula: see text], [Formula: see text] and [Formula: see text] in cell center and periphery. Moreover, by means of Raman spectroscopy we demonstrated the decrease in the relative amounts of reduced cytochromes [Formula: see text], [Formula: see text] and [Formula: see text] in the rod-shaped cardiomyocytes caused by H(2)O(2)-induced oxidative stress before any visible changes. Results of Raman mapping and time-dependent study of reduced cytochromes of complexes II and III and cytochrome [Formula: see text] in cardiomyocytes are in a good agreement with our fluorescence indicator studies and other published data.