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G S Katinas

Publications and source records attributed to G S Katinas.

At least 19 recordsLinked to original sources
PubMed2001

About 8- and approximately 84-h rhythms in endotheliocytes as in endothelin-1 and effect of trauma.

Population densities (PD) of capillaries (C) and endotheliocytes (E) were determined in pinnal dermis of C57BL mice before and after trauma. Moving (and overall) least-squares spectra before trauma detected in EPD (versus CPD) pronounced 3.5-day (circasemiseptan) and 8-h oscillations corresponding to components of the endothelin-1 chronome in human blood plasma reported earlier. Circadians were more pronounced in CPD. After trauma, circasemiseptan oscillations appeared also in CPD; their period gradually shortened and in two weeks split into about 2.5- and about 4.5-day oscillations; and circadian components became very pronounced. The pre-traumatic chronome was not restored within three weeks following trauma.

Animals↗
PubMed2001

Near 10-year and longer periods modulate circadians: intersecting anti-aging and chronoastrobiological research.

Biological cycles with relatively long and some unusual periods in the range of the half-week, the half-year, years, or decades are being discovered. Their prior neglect constituted a confounder in aging and much other research, which then"flew blind" concerning the uncertainties associated with these cycles when they are not assessed. The resolution of more about 10-year and other cycles, some reported herein, replaces the admission of complete unpredictability, implied by using the label "secularity." Heretofore unaccounted-for variability becomes predictable insofar as it proves to be rhythmic and is mapped systematically to serve as a battery of useful reference values. About 10-year cycles in urinary 17-ketosteroid excretion and in heart rate and its variability, among others, are aligned with cycles of similar length in mortality from myocardial infarction. Associations accumulate between cycles of natural physical time structures, chronomes such as the 10.5-year (circadecennian) Schwabe and the 21-year (circavigintunennian) Hale cycles of solar activity, and chronomes in biota. There are about 50-year (circasemicentennian) cycles in mortality from stroke in Minnesota and in the Czech Republic and also in human morphology at birth, the latter result reducing the likelihood that these cycles are purely human made. Associations among large populations warrant long-term systematic coordinated sampling of natural physical and biological variables of interest for the design of countermeasures against already documented elevated risks of stroke, myocardial infarction, and other catastrophic diseases, notably in elderly adults. New findings will be introduced against the background of the documented value of mapping rhythms in medicine and gerontology. In both these fields, rhythms promise the seeming paradox of better care for less.

17-Ketosteroids↗
PubMed1998

[Left and right brain hemispheres in the regulation of pain sensitivity biorhythms in mice during stress].

The foot-shock effects on ultradian and circadian rhythms of pain sensitivity in the SHR mice were studied after unilateral brain cortex hemisphere inactivation by means of the Leao spreading depression. Under acute painful stress, the left hemisphere partially loses its synchronizing effect on circadian rhythm and supports the 12-hour and particularly 6-hour periodicities. The left hemisphere effect dominates in intact animals under stress. The right hemisphere under the same conditions mainly loses its activating effect on circadian rhythm and supports the 8- and 16-hour periodicities. The right hemisphere effect dominates in animals under stress operated 2-3 days prior to the experiment.

Activity Cycles↗
PubMed1992

[The dynamics of the reparative regeneration of the rat epidermis exposed to lysylproline].

Under study was the spatial distribution of mitotic activity (MA) of the rat epidermis in the process of reparative regeneration of the skin for a distance of 6 mm aside from the wound margin, as well as the action of lysyl-proline (LP) on the process which is a product of natural decay of collagen. The wound was made by cutting a skin flap (0.5 x 3 cm) from the area of the back. A teflon ring was introduced through the incision in the cranial direction at a distance of 3 cm. Control animals were given 1 ml of the isotonic solution of sodium chloride injected in the hole of the ring, for experimental animals the solution additionally contained 20 mkg of LP. Healing of the wound in control and experimental animals had the features generally corresponding to the regularities established earlier. It was also found that mitotic activity was growing irregularly forming waves. During 11 days of observations these waves sometimes came nearer to the center of the wound, sometimes moved away. The influence of LP manifested itself in the waves of MA reaching the wound center 1 day earlier, and the approximation and divergence of the waves were smoother, MA was higher and epithelialization of the wound surface also came 1 day earlier. Since the contraction of the wound in experimental animals was also more rapid (activization from the 3rd day), a conclusion can be made of the stimulating influence of LP on the course of the reparative regeneration of the epidermis observed as long as 1.5 weeks after a single injection of LP.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

[Changes in the cell population of the thymus-dependent area of the regional lymph nodes following skin flap grafting].

In the paracortical zone of the regional lymph node changes in the cell population density of small and middle lymphocytes, immunoblasts, immature and mature plasma cells are taken into consideration. The observations are carried out for 954 h after transplantation. As demonstrates the analysis of the process segmentation, certain stages of the changes are revealed with duration of 150-160 h; that corresponds to circadian (circaseptan) range of biological rhythms. The duration of the first stage makes about a half of the circaseptan period. In quantitative changes of every cell type a slow trend and a periodical component are present. It is possible to suppose that during the first 3-4 days mobilization of cell resources takes place, further up to 13-16 days active reactions occur, directed to exfoliation of allogenic tissue components, and then after the exfoliation of the graft the amount of the cells becomes stable, however, rhythmical fluctuations are preserved. The reaction of the cell composition in the paracortical zone of the lymph nodes is in concord with the dynamics of changes in the cell population and in the transplant itself.

Animals↗
PubMed1987

[Succinate dehydrogenase activity of brachial muscle antagonists after decrease in the force load at various times of the day in rats].

In 140 male rats of Wistar strain the distal part of one thoracic extremity has been amputated in such a way that places of the brachial muscle fixation remained intact. This resulted in decrease of the force component of muscle contractions (more intensive in the musculus triceps brachii) without essential swing and speed of movements. The operation was performed during one day at three series: at 7 a. m. 3 p. m. and 11 p. m. During following 45 days the muscles developing various contraction force were studied: the medial head of the musculus triceps brachii and brachial muscle. Succinate dehydrogenase (SDG) activity in muscle fibers (MF) was estimated photometrically. In MF initially characterized with various SDG activity, attention was payed to its dynamics and also relation of the fibers number, possessing various level of the enzymatic activity was taken into consideration. SDG activity in MF and relation of various MF change wavy-like, fluctuating from the control meaning and returning to them again. MF with different SDG activity do not similarly react to a sharp decrease of the force loading. Fibers with high enzymatic activity react to changes of the force loading immediately, intensity of the reaction at this stage slightly depends on degree of biomechanical changes; at later stages the response is differentiated: if the loading is decreased considerably (musculus triceps brachii), the process continues developing and increasing uninterruptedly, if it decreases moderately (brachial muscle)--it stabilizes and even has tendency to adaptation and returning towards the control state.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Pathogenesis of experimental thyrotoxic myopathy.

Focal degenerative changes of skeletal muscle fibers (decrease in mean diameter, excessive axonal branching and a decrease in the mean diameter of motor end-plates together with a reduction of their acetylcholinesterase levels) were found by means of the experimental model thyrotoxic myopathy in mice compared to controls. A decrease in protein kinase affinity to cAMP and an increase in the number of nucleotide binding sites were revealed with a simultaneous decrease in cAMP level. The weakening of hormonal control of cAMP-dependent processes is probably the basic cause of muscular weakness and structural changes in skeletal muscles in thyrotoxic myopathy.

Acetylcholinesterase↗
PubMed1985

[Changes in the activity of succinate dehydrogenase in muscle fibers of functionally different muscles in the rat after a reduction in exertion--hypodynamia].

In 105 male rats of Wistar strain distal parts of one of the thoracic extremities are amputated with keeping intact the places where the brachial muscle is fixed. This does not restrict the volume of the brachium movements but essentially decreases their dynamic component (power loading). For 45 days dynamics of succinate-dehydrogenase (SDG) activity is being revealed in muscle fibers (MF) of functionally different muscles: m. brachialis, m. serratus ventralis and m. triceps brachii (the medial head). Average tendency of the process, changes in the distribution margins, asymmetry and kurtosis are taken into account. Under hypodynamia reconstruction of the MF has a wavy character with a gradually longer period of fluctuations. In all the muscles appear MF with a greater than in the control SDG activity. In the medial head of the m. triceps brachii the fibers with the lowest SDG activity disappear. The amount of MF with the lowest activity decreases, while those with the higher--increases, the process being more pronounced in the m. triceps brachii. The amount of MF with middle activity of the enzyme remains nearly unchanged. MF with different initial enzymatic activity do not change simultaneously. The degree of the changes in the fibers and the power leading are connected with each other, the fibers with the low initial SDG activity including into the reaction at a sharper decrease of the latter. The changes in quantitative ratio of MF with different SDG activity are not the same in every muscle studied.

Animals↗
PubMed1985

[Size of cardiomyocytes in different regions of the rat heart].

In rats after alcaline dissociation of the heart at the state of systol and diastol, length and width of cardiomyocytes have been measured, their volume has been calculated. Statistical characteristics of distribution connected with the first four moments have been taken into consideration. Certain size differences of cardiomyocytes in five cardiac parts have been revealed, as well as peculiarites of their variability that is connected with an individual and internal changeability. In the atria predominates the first, in the ventricles--the second. If the internal changeability of the cardiomyocytes in all the cardiac parts is mainly the same, the individual one--is different (in the atrii it is 2 times as great, in the interventricular septum it is the same as in the atrii). The individual changeability of the cardiomyocytes volume is also greater than that of their size. This also proves the variability of their proportions. The degree of their contractility makes 11--20%, differences between the cardiac parts are not significant. The data obtained could be used as normatives for various experiments.

Animals↗
PubMed1984

[Pathogenesis of experimental thyrotoxic myopathy].

The data obtained in mice with experimental thyrotoxic myopathy included a decrease in the median diameter of the muscle fibers by 17.1 per cent and various focal degenerative changes in less than 20 per cent of the muscle fibers; a statistically significant elevation in the activity of alpha-glycerophosphate dehydrogenase, as well as a reduction in phosphorylase activity and glycogen levels. There was also a significant diminution in the median diameter of the motor terminal plates, a decrease in cholinesterase activity and intensified collateral ramification of the distal axons. The major cause of the muscular weakness and structural changes in the skeletal muscles in thyrotoxic myopathy seems to lie in lowered cAMP concentrations and a weakened cAMP-dependent regulation of protein kinase.

Animals↗