Non-perikariális elemek a központi idegrendszeri ischaemiában = Non-perikaryal elements in the central nervous system ischaemia

Az agyi vérellátási zavarok racionális terápiáj nem képzelhető el az agyi keringés szabályzásában részt vevő tényezők és mechanizmusok feltérképezése nélkül. Ezek kutatása során ezideig háttérbe szorult a non-perikariális elemek (axonok, endothelialis sejtek, vér-agy gát) agyi keringési hatásainak vizsgálata a vérvesztés, keringési shock, agyi érelzáródás, cukorbetegség során. Altatott állatokon, agykérgi mikroereken, végzett vizsgálataink e kérdéskörben a következő jelentősebb megállapításokhoz vezettek:(1) Normál artériás nyomás mellett a CO2 agyi áramlásfokozó hatása nitrogén monoxid szabadgyökök közvetítésével jön létre. (2) Súlyos vérnyomásesés okozta agyi ischemiában a CO2 klasszikus agyi értágító hatása megfordul, érszűkítő hatást vált ki. (3) Vérzéses shock dekompenzált fázisában a vér-agy gát áteresztővé válik, ennek oka az érfali endotelsejteket összetartó occludin és cadherin expresszió csökkenése. (4) Szomatikus fájdalomingerek hatására az agy regionális véráramlása nő, a teljes agyi vértérfogat nem változik. (5) Inzulin-rezisztens állapotban, mely növeli a stroke kialakulásának veszélyét, az agyi erek endotelium-függő vazodilatációja csökken, ez a ciklooxigenáz enzim által mediált folyamatok károsodásának a következménye, | The role of non-perikaryal elements (axons, endothelial cells, blood-brain barrier) of the brain in the regulation of cerebral blood flow (CBF) is incomplete. In the present studies this question was investigated. Main findings: (1) Vasodilatory action of the CO2 in the cerebrovascular bed is mediated by nitric oxide /NO/ (2)In severe arterial hypotension, the classic cerebral vasodilatory effect of CO2 is reversed: increased paCO2 results in decreased CBF. (3) In hemorrhagic shock the blood-brain barrier function is lost as a result of reduced occludin and cadherin expression. (4) Painful somatic afferent stimulation results in a significant increase of the regional cerebral blood flow (thalamus, somatosensory cortex) while total cerebral blood volume remains unchanged. (5) Endothelium-dependent cerebral vasodilation is significantly reduced in insulin-resistant animals as a consequence of disturbed cyclooxigenase mediated processes. (6) The PARP enzyme plays an important role in the development of ischemic brain damage: selective blockade of PARP results in a significant decrease of the infarct area of the brain, both in the gray and white matter

A hem-oxigenáz és a nitrogén monoxid szintáz reakcióutak szerepe és kölcsönhatásai az agyi vérkeringés szabályozásában = Role of heme oxygenase and nitric oxide synthase pathways and their interactions in the regulation of the cerebral circulation.

Megállapítottuk, hogy az endogén CO kettős hatást fejt ki az agyi véráramlására: egyfelől prosztanoidok által közvetített vazodilatációt vált ki, másrészt viszont gátolja az NO szintézisét és így vazokonstrikciót okoz. Leírtuk továbbá az agyi vérkeringés alkalmazkodási képességét az NO hiányához, valamint igazoltuk hogy e folyamat független a hemoxigenáz és ciklooxigenáz reakcióutaktól. NO hiányában az agyi erek érzékennyé válnak a tromboxán A2 vazomóciót kiváltó hatásával szemben, ami az agyi véráramlás oszcillációjához és vazospazmus kialakulásához vezethet különböző kórélettani állapotokban. Leírtuk a prosztaciklin kompenzációs szerepét a koronária-keringés területén NO-hiányában. Igazoltuk, hogy a nikotinsav-okozta flush-reakció a PUMA-G receptorok által aktivált immunsejtekből történő prosztaglandin D2- és E2-felszabadulás következménye. | Our studies have shown that endogenous carbon monoxide (CO) has a dual influence on the cerebral circulation: on one hand it induces prostanoid-mediated vasodilation but on the other hand reduces the blood flow by inhibition of nitric oxide (NO) synthesis. Furthermore, we have demonstrated the ability of the cerebral circulation to compensate the loss of NO availability and that this compensation does not involve the heme oxygenase or cyclooxygenase pathways. In the absence of NO the cerebral vessels become vulnerable to thromboxane A2-induced vasomotion which may lead to cerebrocortical blood flow oscillations and vasospasm in certain pathophysiological states. In the coronary circulation prostacyclin was shown to act as a compensatory mediator in the absence of NO. We have shown that nicotinic acid-induced flushing is mediated by PUMA-G receptor-dependent production of prostaglandin D2 and E2 by bone marrow derived immune cells

How to not trade water for carbon with tree planting in water-limited temperate biomes?

The most widespread nature-based solution for mitigating climate change is tree planting. When realized as forest restoration in historically forested biomes, it can efficiently contribute to the sequestration of atmospheric carbon and can also entail significant biodiversity and ecosystem service benefits. Conversely, tree planting in naturally open biomes can have adverse effects, of which water shortage due to increased evapotranspiration is among the most alarming ones. Here we assessed how soil texture affects the strength of the trade-off between tree cover and water balance in the forest-steppe biome, where the global pressure for afforestation is threatening with increasing tree cover above historical levels. Here we monitored vertical soil moisture dynamics in four stands in each of the most common forest types of lowland Hungary on well-drained, sandy (natural poplar groves, and Robinia and pine plantations) and on poorly drained, silty-clayey soils (natural oak stands and Robinia plantations), and neighboring grasslands. We found that forests on sand retain moisture in the topsoil (approx. 20 cm) throughout the year, but a thick dry layer develops below that during the vegetation period, significantly impeding groundwater recharge. Neighboring sandy grasslands showed an opposite pattern, with often dry topsoil but intact moisture reserves below, allowing deep percolation. In contrast, forests on silty-clayey soils did not desiccate lower soil layers compared neighboring grasslands, which in turn showed moisture patterns similar to sandy grasslands. We conclude that, in water-limited temperate biomes where landscape-wide water regime depends on deep percolation, soil texture should drive the spatial allocation of tree-based climate mitigation efforts. On sand, the establishment of new forests should be kept to a minimum and grassland restoration should be preferred. The trade-off between water and carbon is less pronounced on silty-clayey soils, making forest patches and wooded rangelands viable targets for both climate mitigation and ecosystem restoration

Maintaining scattered trees to boost carbon stock in temperate pastures does not compromise overall pasture quality for the livestock

Scattered trees in wood-pastures represent outstanding conservation value by providing microhabitats for a variety of organisms. They also diversify ecosystem services by creating shade for livestock, and capturing and storing carbon. However, trees in wood-pastures are declining Europe-wide and an appropriate legal environment to maintain them is mostly lacking. Here we looked beyond the well-documented beneficial effects of trees and assessed potential ecosystem disservices, which may drive the controversial appreciation of trees. In a grazing exclusion experiment, we assessed the effect of trees on herbage production in wood-pastures from semiarid continental to humid montane areas in the temperate deciduous forest ecoregion, and found that trees have a suppressive effect throughout the year, although herbage nutritive value, as indicated by herbage nitrogen content, seems to be improved in spring. When we up-scaled the local ecosystem disservice on herbage yield to entire wood-pastures, the loss remained below 3%, which is lower than reported gains in livestock production due to free access to shade. Thus, the motivation for the under-appreciation of trees by land managers and decision makers may lie in that trees suppress herbage production, but the importance of this effects is offset by the magnitude of the beneficial services of trees. We recommend current wood-pasture stakeholders to revisit their attitude towards scattered trees and encourage tree planting campaigns and tree-based climate mitigation strategies to consider the protection of trees in wood-pastures and the establishment of young ones in currently open pastures up to traditionally low tree cover proportions, as livestock production is unlikely to be compromised by this action

Bee pollination and association of apricot varieties

Apricot yields are highly variable according to the season. The variation is caused mainly by the adversities during the critical processes of floral biology, i.e. blooming and fertilisation. On the basis of information concerning blooming time and mutual compatibility relations of apricot varieties a system of securing regular and adequate yields has been developed. Winter frosts of the continental type are well tolerated by most of the apricots, however, after the end of rest period, flower buds are loosing frost tolerance, 'rapidly. Being one of the fruit species blooming earliest during the early spring, apricot start to bloom in Hungary around the end of March or early April as a mean of many years, but it also happened, exceptionally that apricot started to bloom at February 20 (at Letenye South Hungary). The early season, exposes the floral organs to frost injuries. As a consequence, apricot orchards on the Great Plain produce low yields in 3 years, intermediate yields in other 3 years out of a ten-year-period. Moreover, weather conditions during the blooming period are often unfavourable for pollination. Cool, windy and rainy weather prevents the flight of insects and on the other hand, warm spells shorten the blooming process, nectarines and stigmata get dry and the female gametes loose viability before effective pollination occurres. The fertility of individual cultivars are meeting different obstacles. Apricot cultivars differ greatly in the rate of flowers bearing underdeveloped pistils, which may attain even 60% (e.g. Orangered). New commercial cultivars are often self-incompatible. Local varieties of that type in Hungary are the „óriás" varieties (e.g. Ceglédi óriás, Szegedi mammut), and the new hybrid Ceglédi Piroska. Many of the cultivars are variable in their self-fertility (partially self-fertile): Budapest, Harmat, Korai piros, Mandulakajszi. Inter-incompatibility is also known in apricots. The „óriás " varieties do not fertilise each other. During the growth of fruits, cool spells (2-4 °C) caused severe fruit shed in Ceglédi óriás. Apricot flowers produce pollen and nectar at average rates related to other fruit species, thus bees are attracted sufficiently. Bee visits are very variable according to growing site and season. Most of the bees are pollen gatherers but sometimes nectar suckers are in majority. Bee pollination is necessary not only for the self-incompatible varieties but also to enhance the yield of self-fertile varieties. Taking the blooming and fertility relations of the cultivars into account, plantations should not exceed two rows to a particular self-incompatible varieties, and possibly two different polliniser varieties are suggested to be planted as flanking the block in question. In commercial plantations 2 to 4 bee colonies per hectare are proposed to move for the whole blooming period. &nbsp

Bee pollination and association of apricot varieties

Apricot yields are highly variable according to the season. The variation is caused mainly by the adversities during the critical processes of floral biology, i.e. blooming and fertilisation. On the basis of information concerning blooming time and mutual compatibility relations of apricot varieties a system of securing regular and adequate yields has been developed. Winter frosts of the continental type are well tolerated by most of the apricots, however, after the end of rest period, flower buds are loosing frost tolerance, 'rapidly. Being one of the fruit species blooming earliest during the early spring, apricot start to bloom in Hungary around the end of March or early April as a mean of many years, but it also happened, exceptionally that apricot started to bloom at February 20 (at Letenye South Hungary). The early season, exposes the floral organs to frost injuries. As a consequence, apricot orchards on the Great Plain produce low yields in 3 years, intermediate yields in other 3 years out of a ten-year-period. Moreover, weather conditions during the blooming period are often unfavourable for pollination. Cool, windy and rainy weather prevents the flight of insects and on the other hand, warm spells shorten the blooming process, nectarines and stigmata get dry and the female gametes loose viability before effective pollination occurres. The fertility of individual cultivars are meeting different obstacles. Apricot cultivars differ greatly in the rate of flowers bearing underdeveloped pistils, which may attain even 60% (e.g. Orangered). New commercial cultivars are often self-incompatible. Local varieties of that type in Hungary are the „óriás" varieties (e.g. Ceglédi óriás, Szegedi mammut), and the new hybrid Ceglédi Piroska. Many of the cultivars are variable in their self-fertility (partially self-fertile): Budapest, Harmat, Korai piros, Mandulakajszi. Inter-incompatibility is also known in apricots. The „óriás " varieties do not fertilise each other. During the growth of fruits, cool spells (2-4 °C) caused severe fruit shed in Ceglédi óriás. Apricot flowers produce pollen and nectar at average rates related to other fruit species, thus bees are attracted sufficiently. Bee visits are very variable according to growing site and season. Most of the bees are pollen gatherers but sometimes nectar suckers are in majority. Bee pollination is necessary not only for the self-incompatible varieties but also to enhance the yield of self-fertile varieties. Taking the blooming and fertility relations of the cultivars into account, plantations should not exceed two rows to a particular self-incompatible varieties, and possibly two different polliniser varieties are suggested to be planted as flanking the block in question. In commercial plantations 2 to 4 bee colonies per hectare are proposed to move for the whole blooming period. &nbsp

The effect of spring frosts on the nectar production and the bee visitation of fruit trees

Fruit tree species suffered very strong spring frosts in 1997 in Hungary. This caused partial or total damages at buds and flowers depending on site and time of blooming. It was demonstrated at a number of experiments that frost and cold weather also strongly affected the nectar production of surviving flowers. No or very little amount of nectar was measured in flowers first of all of early blooming fruit tree species (apricot) but also of pear and apple in some places. In spite of this fact intensive honeybee visitation was detected in the flowers of fruit trees that suffered partial frost damage only at those sites where honeybee colonies were placed in or at the experimental plantations and the lack of sufficient amount of nectar did not affected bee behaviour seriously on fruit flowers. This means that bad nectar production failed to affect bee visitation of fruit trees definitely. The reason for this was the fact that not only fruit trees but another early bee plants (wild plants, too) suffered frost damage. Accordingly, in lack of forage bees intensively searched for food at blooming fruit trees with some living flowers. Consequently, there was an acceptable yield at those plantations where bud and flower damage was not complete. Accordingly, intensive bee visitation (that is moving additional bee colonies to overpopulate fruit orchards with honeybees) can be an effective tool to decrease or eliminate the detrimental effect of spring frost on the yield of fruit trees where bud or fruit damage is not too high. &nbsp

The effect of spring frosts on the nectar production and the bee visitation of fruit trees

Fruit tree species suffered very strong spring frosts in 1997 in Hungary. This caused partial or total damages at buds and flowers depending on site and time of blooming. It was demonstrated at a number of experiments that frost and cold weather also strongly affected the nectar production of surviving flowers. No or very little amount of nectar was measured in flowers first of all of early blooming fruit tree species (apricot) but also of pear and apple in some places. In spite of this fact intensive honeybee visitation was detected in the flowers of fruit trees that suffered partial frost damage only at those sites where honeybee colonies were placed in or at the experimental plantations and the lack of sufficient amount of nectar did not affected bee behaviour seriously on fruit flowers. This means that bad nectar production failed to affect bee visitation of fruit trees definitely. The reason for this was the fact that not only fruit trees but another early bee plants (wild plants, too) suffered frost damage. Accordingly, in lack of forage bees intensively searched for food at blooming fruit trees with some living flowers. Consequently, there was an acceptable yield at those plantations where bud and flower damage was not complete. Accordingly, intensive bee visitation (that is moving additional bee colonies to overpopulate fruit orchards with honeybees) can be an effective tool to decrease or eliminate the detrimental effect of spring frost on the yield of fruit trees where bud or fruit damage is not too high. &nbsp

How to not trade water for carbon with tree planting in water-limited temperate biomes?

The most widespread nature-based solution for mitigating climate change is tree planting. When realized as forest restoration in historically forested biomes, it can efficiently contribute to the sequestration of atmospheric carbon and can also entail significant biodiversity and ecosystem service benefits. Conversely, tree planting in naturally open biomes can have adverse effects, of which water shortage due to increased evapotranspiration is among the most alarming ones. Here we assessed how soil texture affects the strength of the trade-off between tree cover and water balance in the forest-steppe biome, where the global pressure for afforestation is threatening with increasing tree cover above historical levels. Here we monitored vertical soil moisture dynamics in four stands in each of the most common forest types of lowland Hungary on well-drained, sandy (natural poplar groves, and Robinia and pine plantations) and on poorly drained, silty-clayey soils (natural oak stands and Robinia plantations), and neighboring grasslands. We found that forests on sand retain moisture in the topsoil (approx. 20 cm) throughout the year, but a thick dry layer develops below that during the vegetation period, significantly impeding groundwater recharge. Neighboring sandy grasslands showed an opposite pattern, with often dry topsoil but intact moisture reserves below, allowing deep percolation. In contrast, forests on silty-clayey soils did not desiccate lower soil layers compared neighboring grasslands, which in turn showed moisture patterns similar to sandy grasslands. We conclude that, in water-limited temperate biomes where landscape-wide water regime depends on deep percolation, soil texture should drive the spatial allocation of tree-based climate mitigation efforts. On sand, the establishment of new forests should be kept to a minimum and grassland restoration should be preferred. The trade-off between water and carbon is less pronounced on silty-clayey soils, making forest patches and wooded rangelands viable targets for both climate mitigation and ecosystem restoration

Maintaining scattered trees to boost carbon stock in temperate pastures does not compromise overall pasture quality for the livestock

Scattered trees in wood-pastures represent outstanding conservation value by providing microhabitats for a variety of organisms. They also diversify ecosystem services by creating shade for livestock, and capturing and storing carbon. However, trees in wood-pastures are declining Europe-wide and an appropriate legal environment to maintain them is mostly lacking. Here we looked beyond the well-documented beneficial effects of trees and assessed potential ecosystem disservices, which may drive the controversial appreciation of trees. In a grazing exclusion experiment, we assessed the effect of trees on herbage production in wood-pastures from semiarid continental to humid montane areas in the temperate deciduous forest ecoregion, and found that trees have a suppressive effect throughout the year, although herbage nutritive value, as indicated by herbage nitrogen content, seems to be improved in spring. When we up-scaled the local ecosystem disservice on herbage yield to entire wood-pastures, the loss remained below 3%, which is lower than reported gains in livestock production due to free access to shade. Thus, the motivation for the under-appreciation of trees by land managers and decision makers may lie in that trees suppress herbage production, but the importance of this effects is offset by the magnitude of the beneficial services of trees. We recommend current wood-pasture stakeholders to revisit their attitude towards scattered trees and encourage tree planting campaigns and tree-based climate mitigation strategies to consider the protection of trees in wood-pastures and the establishment of young ones in currently open pastures up to traditionally low tree cover proportions, as livestock production is unlikely to be compromised by this action