Morphofunctional features of the development of the thyroid gland of Dicrostonyx torquatus during the drop in population stage

By means of the histostereometrical method, peculiarities of the thyroid gland formation have been studied in the lemming (Dicrostonyx torquatus) fetuses and newborns at the stage of the population quantity drop, as well specificity of the organ's morphofunctional state during the postnatal period. On the 14th prenatal day the thyroid gland already has the follicular structure. Up to the 19th day progressive follicular growth, accumulation of colloid and increase of its density occur. On the 19th-20th days, as well as in newborn animals, there are certain signs, demonstrating as essential activation of the thyroid gland function. In the newborn animals cavities of the completely formed follicles are devastated. During the postnatal period again growth of follicles, accumulation of colloid are observed, signs of hypersecretion of the hypophysis appear.     

The hypothalamo-hypophysial system of the lemming, Dicrostonyx torquatus Pallas. III. Population aspects of neuroendocrine regulation

The structure and ultrastructure of the following regions of the hypothalamo-hypophysial neurosecretory system (HHNS) in the population cycle of lemming were studied: supraoptic (SON), paraventricular (PVN) and arcuate nuclei (AN), the median eminence (ME) and posterior pituitary (PP). Being compared to the state of endocrine glands and gonads, and the level of reproduction stress in the population cycle of the lemming described earlier, the obtained data revealed a certain regularity. First, at the stages of decrease, increase and in the first period of the stage of population peak the activity of the SON-PP complex and AN is gradually increased. This coincides with intensified reproduction, intensified functioning of the thyroid gland and adrenal cortex. Second, while the population is decreasing, all the above functions become depressed, except that of the thyroid gland which, on the contrary, becomes active. In the second period of the stage of population peak, when reproduction stops abruptly, this regularity, however, does not hold, the activity of SON-PP complex and AN is sharply lowered, whereas that of PVN becomes very high. The structure of the thyroid damaged as a result of previous hyperfunction, is restored, and the adrenal cortex shows signs of hypercorticism. The present work is devoted to specificity of the HHNS functioning at the stage of population peak, referred to as crucial, and the pathways and mechanisms by which neurohormones produced by this system can affect the endocrine glands. In addition, the causes likely to lead to the mass death of animals at this stage, and biological significance of this fact are also given attention to.     

Dinitrosyl iron complexes with glutathione largely relieve rats of experimental endometriosis

A study was made of the effect of binuclear dinitrosyl iron complexes (DNIC) with glutathione in rats with experimental endometriosis. The latter was induced in an autotransplantation model, where two fragments of endometrium with myometrium (2 × 2 mm) from the left uterine horn were grafted to the inner surface of the anterior abdominal wall. After 4 weeks, the test animals received i.p. injections of 0.5 mL DNIC-glutathione at a dose of 12.5 μmol/kg daily for 12 days. This treatment more than halved the total volume of endometrioid tumors. Remarkably, tumor growths from grafts in control rats were often attended by tumors spontaneously arising nearby or in other locations; no such secondary tumors were observed in DNIC-treated animals. The EPR signal with g _av = 2.03 characteristic of protein-bound DNIC with thiol ligands was recorded in liver and endometrioid implants of control as well as treated animals. Activation of ribonucleotide reductase, detected by a doublet EPR signal at g = 2.0 with 2.3-mT hyperfine splitting, was found in small tumors. The beneficial effect of DNIC-glutathione was suggested to be due to DNIC breakdown near the tumors, with release of a large amount of molecular nitric oxide and nitrosonium ions that resulted in selective local cytotoxicity.     

Epidemiology of a tick‐borne viral infection: theoretical insights and practical implications for public health

The morbidity of tick‐borne encephalitis (TBE) varies yearly by as much as 10‐fold among the people of Western Siberia. This long‐term variation is dependent on many factors such as the density of the tick populations, the prevalence of TBE virus (TBEV) among sub‐adult ticks, the yearly virulence of the TBEV, and prophylactic measures. Here we highlight the role of small mammal hosts in the circulation of TBEV through the ecosystem. Refining classical models of non‐viremic horizontal transmission, we emphasize the recently understood fact that the physiological and immunological status of the small mammal hosts affects the tick and virus‐host interactions. In addition to its theoretical interest, our approach may lead to some practical improvements in the precision of epidemiological forecasts and perhaps in forestalling the severity of outbreaks of TBE, or, at least, in forewarning medical authorities and the general public of impending TBE outbreaks.     

Antiviral Activity of Nitrosonium Cations against SARS-CoV-2 on a Syrian Hamster Model

Biophysics - The antiviral action of binuclear dinitrosyl iron complexes with glutathione along with diethyldithiocarbamate against the SARS-CoV-2 virus has been demonstrated on a Syrian hamster...     

New delta8(14)-ketosterols with an oxygenated side chain

New analogues of 3beta-hydroxy-5alpha-cholest-8(14)-en-15-one (15-ketosterol) with modified 17-chains [(22S,23S,24S)- and (22R,23R,24S)-3beta-hydroxy-24-methyl-22,23-oxido-5alpha-cholest-8(14)-en-15-ones and (22RS,23xi,24S)-24-methyl-5alpha-cholesta-3beta,22,23-triol-15-one] were synthesized from (22E,24S)-3beta-acetoxy-24-methyl-5alpha-cholesta-8(14),22-dien-15-one. The chiralities of their 22 and 23 centers were determined by NMR spectroscopy. The isomeric 22,23-epoxides effectively inhibited cholesterol biosynthesis in hepatoma Hep G2 cells (IC50 0.9 +/- 0.2 and 0.7 +/- 0.2 microM, respectively), and their activities significantly exceeded those of 15-ketosterol (IC50 4.0 +/- 0.5 microM), (22E,24S)-3beta-hydroxy-24-methyl-5alpha-cholesta-8(14),22-dien-15-one (IC50 3.1 +/- 0.4 microM), and the 3beta,22,23-triol synthesized (IC50 6.0 +/- 1.0 microM). The English version of the paper: Russian Journal of Bioorganic Chemistry, 2005, vol. 31, no. 3; see also http://www.maik.ru.     

Adaptive reactions of the endocrine system of children living under conditions of contrasting photoperiods

Age-related changes in the levels of pituitary, thyroid, and sex hormones and their dependence on the day length were studied in 242 healthy 10-to 16-year-old boys born and permanently living in the southern part of Arkhangel’sk oblast. It was found that the serum levels of thyroid hormones, gonadotropins, and sex steroids underwent circannual changes. The minimum concentrations of thyroxine, testosterone, and estradiol and the maximum concentrations of triiodothyronine, lutcinizing and follicle-stimulating hormones, and progesterone were associated with the shortest days. In contrast, the longest days were associated with the maximum concentrations of thyroxine, testosterone, and estradiol and the minimum concentrations of triiodothyronine, luteinizing and follicle-stimulating hormones, and progesterone. A factor dependence of the thyroxine, triiodothyronine, testosterone, estradiol, and prolactin concentrations on the day length was found in the group examined. This dependence was more pronounced during the second half of adolescence.     

The dinitrosyl-iron complexes with cysteine block the development of experimental endometriosis in rats

It has been shown that the administration of 0,5 ml of 5 mM aqueous solution of dinitrosyl-iron complexes (DNIC) with cysteine alleviated the development of experimental endometriosis in rats induced by surgical way: the size of endometriomes decreased 1.85 times when the DNIC was added every day during 10 days. The effect was suggested to be due to cytotoxic action of NO molecules and nitrosonium ions (NO+) released from rapidly decomposed DNIC in animal organism on endometriome tissues.