The role of heparin and tissue-type plasminogen activator in the adaptation of the hemostatic system to high altitude]

The role of endogenous heparin and tissue-type plasminogen activator in the middle-period (25 days) adaptation of haemostasis to high altitude (altitude 3200 m) and formation or "high-altitude hypocoagulation" was studied in the experiments on white rats. It was observed that the formation of "high-altitude hypocoagulation" is connected with an increase of heparin and tissue-type plasminogen activator level due to its release from must and endothelial cells to the bloodstream. Histochemical analysis showed that at the course of adaptation to high altitude the increase in blood heparin level was caused by the stimulation of must cells secretory activity. The endothelium of lung vessels is the main source of tissue-type plasminogen activator release into the blood. The existence of interconnection between the changes in haemostasis and stimulation of angiogenesis at high altitude is proposed.     

Effect of photoperiod and thermoperiod on the eclosion rhythm ofTrichogramma evanescens

The dynamics of adult eclosion inTrichogramma evanescens Westw. were studied under (1) constant light and temperature of 20 °C, (2) photoperiods L12:D12 and L16:D8 at 20 °C, (3) thermoperiod 4 h 27 °/20 h 20 °C at constant light, (4) joint action of photo- and thermoperiod. The emergence was arhythmic in constant light combined with constant temperature, while a sharp monophasic rhythm was observed with the isolated action of photo- or thermoperiod. The ‘light-on’ and ‘temperature step-up’ signals were shown to act in one direction. When both signals were combined, they manifested themselveses competing entraining stimuli which, in turn, revealed an apparent individual variation in relative reactivity to the light and temperature signals. Some perspectives which follow from these observations are discussed.     

Effect of transformed steroids on Na,K-dependent ATPase

The transformed steroids containing delta 5-3 beta-hydroxy- or 3 beta, 5 alpha-dihydroxy-6-keto groups in the A/B rings and an additional cycle E (17,20-dihydroxy-delta-lactone, 16,23-pyranone or delta 20(22)-16 alpha, 17 alpha-dihydroxy-23-carbethoxy-side chain) (1 . 10(-5) M) inhibit Na+,K+-ATPase from pig kidney medulla or from ox brain. The steroid structure has a noticeable effect on ATPase inhibition varying from 3 to 26%. The data obtained suggest that the uneven distribution of polar substituents in the steroid molecule is essential for ATPase inhibition by steroid aglycons.     

Heparin secretion by mast cells as an index of the status of the anticoagulant system

The status of the mast cell population was studied and compared after administration of trypsin or alpha-thrombin in similar molar concentrations. Morphometry disclosed a substantial shift of the mast cell population towards light, heparin-free cells within one minute after alpha-thrombin administration. The index of mast cell saturation with heparin dropped below 1. The maximal heparin secretion was observed at the 5th minute of experiment. The morphometric criteria of the mast cell population returned to basal level in 120 minutes. These data along with a significant increase in the level of complex heparin compounds and plasma thrombin time indicate heparin release as a result of the effector action of the anticoagulation system. No changes were observed in the activity of complex heparin compounds and in thrombin time after intravenous injection of trypsin. It is suggested that high heparin secretion by mast cells may serve as criterion of the active status of the anticoagulation system.     

The incorporation of 35S-heparin into mast cells in the rat and its release into the circulatory bed

It was shown that the intensity of the clearance of 35S-heparin in the blood is extremely high in the first 30 minutes after the introduction of the label. Further on the intensity of the clearance was decreased and by the 60th minute only 11 per cent of the radioactivity was left and by the 240th minute--3.7%. It was established that during intravenous introduction of 35S-heparin the obese cells are capable of accumulating it from the blood flow.     

The protective effect of prolil-glycil-proline peptide (PGP) under compound 48/80-induced anaphylactoid reaction in mice

The influence of PGP on compound 48/80-induced anaphylactoid reaction development in mice and on histamine secretion from rat peritoneal mast cells (RPMS) under their activation by compound 48/80 were investigated. Anaphylactoid reaction was caused by intraperitoneal injection of compound 48/80 into mice. The number of animals with manifestations of anaphylactoid reaction symptoms, the severity of these symptoms, the amount of died animals and the time of death were registering during an hour. Mast cells for in vitro investigations were obtained from rats’ peritoneal cavity. Secreted histamine was evaluated from formation of fluorescent product of it’s condensation with ortho-phthalaldehyde. The preventive injection of PGP in mice (15 min before compound 48/80) decreased the mortality rate of animals and intensity of anaphylactoid reaction symptoms. But PGP had no effect on histamine secretion from mast cells under their activation by compound 48/80 in vitro. Results show that there is a component in the mechanism of PGP protective effect under anaphylactoid reaction which is not connected with mast cells stabilization.     

Application of laser interference microscopy (LIM) for investigation of the protective effect of prolyl-glycyl-proline (Pro-Gly-Pro) on mast cells

The effect of peptide prolyl-glycyl-proline (Pro-Gly-Pro) on morphometric parameters of mast cells upon their activation by compound 48/80 or synacten was investigated. Cell image, obtained by the method of laser interference microscopy (LIM), is a distribution of the optical path difference of light (OPD). It evaluates the changes of the individual components of cytoplasm (maxOPD) and the total distribution of OPD (“dry mass”). The changes of “dry mass” in cytoplasm correlate with the changes of the secreted histamine amount (?0.86). Preliminary incubation of mast cells with Pro-Gly-Pro (6 × 10^?5 M) did not change the area, the state of the individual components of the cytoplasm (nucleus) and “dry mass” (histamine vesicles) in cells. The “dry mass” (histamine vesicles) and maxOPD decreased while the release of histamine increased upon the activation of mast cells by compound 48/80 (0.02 mg/mL). Preincubation of cells with Pro-Gly-Pro had no effect. Activation of cells by synacten (2 and 20 μM) led to the increase of the cell area and the reduction of maxOPD and “dry mass” (histamine vesicles). Preincubation of the cells with Pro-Gly-Pro prevented these changes. So, the protective effect of Pro-Gly-Pro was observed in the case of the activation of mast cells by synacten but not by compound 48/80.     

The nature of thyroid hormone receptors. Intracellular functions of thyroxine-binding prealbumin

The effect of tyroxin-binding prealbumin (TBPA) of blood serum on the template activity of chromatin was studied. It was found that the values of binding constants of TBPA for T3 and T4 are 2 X 10(-11) M and 5 X 10(-10) M, respectively. The receptors isolated from 0.4 M KCl extract of chromatin and mitochondria as well as hormone-bound TBPA cause similar effects on the template activity of chromatin. Based on experimental results and the previously published comparative data on the structure of TBPA, nuclear, cytoplasmic and mitochondrial receptors of thyroid hormones as well as on translocation across the plasma membrane and intracellular transport of TBPA, a conclusion was drawn, which suggested that TBPA is the "core" of the true thyroid hormone receptor. It was shown that T3-bound TBPA caused histone H1-dependent conformational changes in chromatin. Based on the studies with the interaction of the TBPA-T3 complex with spin-labeled chromatin, a scheme of functioning of the thyroid hormone nuclear receptor was proposed.     

Host population density influence on host acceptance inTrichogramma

In 7Trichogramma species (Hymenoptera, Trichogrammatidae) the percentage of females, parasitizing at least one host, directly depends on the number of host eggs.Trichogramma females that refusedSitotroga eggs will still oviposit in natural hosts. These refusing females were yet active, moved in test tubes and sometimes contacted the host. It seems that the sequence of behavioural reactions resulting in parasitization is interrupted at the stage of arrestment and host recognition. Host density within a habitat proved to be an important factor in host acceptance. Possible mechanisms that formed the basis of the observed effect (behavioural response to host kairomones, the learning ability, endocrine processes) are discussed.

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Résumé En utilisant l'hôte de laboratoire (Sitotroga cerealella Oliv.) nous avons démontré qu'une partie des femelles refuse la parasitation. L'analyse de la succession des actes constitutifs de la parasitation montre que celle-ci est interrompue au moment de l'acceptation. Le pourcentage des femelles parasitante est en dépendance directe du nombre des ufs de l'hôte. Les résultats de cette étude suggèrent que l'acceptation de l'hôte par le parasitoid est finction de la densité de population de celui-là. Les mécanismes possibles de cette dépendance (la réaction aux kairomones, l'apprentissage, les modification endocrines) sont discutés.

     

The influence of host's age on the selectivity of parasitism and fecundity ofTrichogramma

Laboratory studies showed that ♀♀ ofTrichogramma embryophagum (Hartig) andT. semblidis (Aurivillius) when offered an alternative of young and old eggs of the grain moth,Sitotroga cerealella Oliv., prefer ovipositing into young eggs. The fecundity of ♀♀ that are simultaneously offered both young and old eggs was lower in comparison to ♀♀ offered only young eggs (inspite of the fact that in both variants young eggs were in excess). The results suggest that old eggs can inhibit the oviposition of some species ofTrichogramma.