Influence of the building energy efficiency on indoor air temperature: The case of a typical school classroom in Serbia

Greenhouse gases emission as well as total energy consumption in buildings of public importance, such as schools, municipal buildings, health care centers, can be significantly reduced by increasing buildings’ energy efficiency. Buildings’ energy consumption adds up to 37% of total energy consumption in the EU countries. In the Republic of Serbia this amount is significantly higher, about 50%. School buildings are considered as one of the most diverse structures from the point of energy-efficient design and construction. The main aim of this paper is to determine the most appropriate settings for possible improvements in energy efficiency and temperature comfort inside a typical primary school classroom in Serbia. The energy efficiency analysis was performed during the heating season for the naturally ventilated primary school classroom located in the eastern Serbia region. The analysis was performed using novel CFD model, suggested in this paper. The suggested model was used to solve two hypothetical scenarios. The first scenario simulates the temperature field in classroom with current energy characteristic envelope of the school building. The calculated numerical data from the first scenario were compared with in-situ measurements values of temperature and wall heat fluxes and showed satisfying accuracy. The second scenario was simulated to indicate possible improvements, which would allow energy consumption decrease and thermal quality enhancement. The analyzed results, calculated using the suggested numerical model under the second scenario conditions, showed that using appropriate set of measures, it is possible to obtain desired temperature comfort levels without need for increase in the building energy consumption

Effects of nerve and fibroblast growth factors on the production of nitric oxide in experimental model of Huntington's disease

The role of nitric oxide (NO) in neurological diseases represents one of the most studied, yet controversial subjects in physiology. The aim was to examine the effects of intrastriatal injection neurotrophins (nerve growth factors-NGF, fibroblast growth factors-FGF) in order to investigate the possible involvement of NO in quinolinic acid (QA) induced striatum toxicity in the rat model of Huntington's disease (HD). QA was administered unilaterally into the striatum of adult Wistar rats in a single dose of 150 nM. The other two groups of animals were pretreated immediately before QA application with NGF and FGF, respectively. Control group was treated with 0.9% saline solution in the same manner. Animals were decapitated 7 days after the treatment. Nitrite levels were significantly decreased both in the ipsi- and contra lateral striatum and forebrain cortex of NGF- and FGF-treated animals compared with QA treatment. These results indicated a temporal and spatial propagation of oxidative stress and spread protective effects of NGF and FGF on the forebrain cortex, the distant structure, but tightly connected with striatum, the place of direct neurotoxin damage. Neurotrophins could be the potential neuroprotective agents in HD

Cerebrospinal fluid and plasma concentration of soluble intercellular adhesion molecule1, vascular cell adhesion molecule1 and endothelial leukocyte adhesion molecule in patients with acute ischemic b

Background. Leukocyte migration into the ischemic area is a complex process controlled by adhesion molecules (AM) in leukocytes and endothelium, by migratory capacity of leukocytes and the presence of hemotaxic agents in the tissue. In this research it was supposed that in the blood and cerebrospinal fluid (CSF) of patients in the acute phase of ischemic brain disease (IBD) there were relevant changes in the concentration of soluble AM (sICAM-1 sVCAM-1 and sE-selectin), that could have been the indicators of the intensity of damaging processes in central nervous system (CNS). Methods. The study included 45 IBD patients, 15 with transient ischemic attack (TIA) 15 with reversible ischemic attack (RIA), and 15 with brain infarction (BI) of both sexes, mean age 66±7. Control group consisted of 15 patients with radicular lesions of discal origin, subjected to diagnostic radiculography without the signs of interruption in the passage of CSF. Changes of selected biochemical parameters were determined in all patients in frame 72 hours since the occurence of an ischemic episode. Concentrations of soluble AM were determined in plasma and CSF by ELISA. Total number of leukocytes (TNL) in peripheral blood was determined by hematological analyzer. Results. The results showed that during the first 72 hrs of IBD significant increases occured in TNL and that the increase was progressive compared to the severeness of the disease. Significant increase of soluble AM concentration was shown in plasma of IBD patients. The increase was highest in BI somewhat lower in RIA and the lowest in TIA patients compared to the control. In CSF concentrations of sICAM-1, sVCAM-1 and sE-selectin demonstrated similar increasing trend as in plasma. Conclusion. TNL, as well as the soluble AM concentrations in plasma and CSF, were increased during the acute IBD phase and progressive in relation to the severeness of the disease, so that they might have been the indicators of CNS inflammatory reaction intensity. Furthermore, the results indicated their role in IBD pathogenesis and offered the possibility of researching the application of antagonists and/or activity modulators of some of them in IBD therapy

Influence of NG-nitro-L-arginine methyl ester on clinical and biochemical effects of methylene blue in pentylenetetrazole-evoked convulsions

Background/Aim. Despite years of research in a number of experimental models the question whether nitric oxide (NO) and methylene blue (MB) have pro- or anticonvulsant effects remains to be fully resolved. Methods. In adult Wistar rats the influence of a nonselective inhibitor of nitric oxide synthase NG-nitro-L-arginine methyl ester (LNAME, 10µg) on clinical and biochemical effects of MB (10µg) given before the intraperitoneally administered chemical convulsant pentylenetetrazole (PTZ, 80 mg/kg) was examined. MB and L-NAME were applied intracerebroventricularly. PTZ application was followed by a 4- minute observation time, after which rats were sacrificed and elements of oxido-reductive balance were measured in a crude mitochondrial fraction of forebrain cortex, hippocampus and striatum. Results. Convulsive responses (forelimb dystonia - FLD, generalised clonic- and clonic-tonic convulsions - GCC and GCTC respectively) were observed in all rats received PTZ, together with significantly decreased lipid peroxidation in the forebrain cortex and striatum and increased superoxide dismutase activity in the hippocampus, in comparison to controls (saline treated). It was registered anticonvulsant effects of L-NAME pretreatment. However, these effects were insignificant. In the hippocampus of these animals there was decreased lipid peroxidation (p < 0.01, p < 0.05 vs saline-treated and PTZ-treated rats, respectively) and reverted PTZ-induced increase of superoxide dismutase activity. But MB individually pretreatment significantly decreased the incidence of CTCs and GCCs (FLD: p = 0.0513), prolonged the convulsive latent time for FLD, GCTCs and GCCs, in all the examined brain regions increased lipid peroxidation and decreased the level of superoxide anion. Administration of L-NAME 10 minutes before MB reverted all MB-evoked clinical and biochemical effects. Conclusion. Methylene blue applied individually before PTZ has strong anticonvulsant effects that were eliminated by L-NAME pretreatment. These effects and changed biochemical parameters in the brains of animals treated by L-NAME before MB in comparison to MBtreated group suggest involvement of NO in MB's effects in the animal model of PTZ-evoked convulsions.Uvod/Cilj. I pored višegodišnjeg istraživanja na različitim eksperimentalnim modelima, nije potpuno odgovoreno na pitanje da li azot-oksid (NO) i metilen plavo (MP) deluju konvulzivno ili antikonvulzivno. Metode. Na odraslim pacovima Vistar soja ispitivan je uticaj NG-nitro-L-arginin metil estra (L-NAME, 10 µg), neselektivnog inhibitora azot oksid sintaze, na kliničke i biohemijske efekte metilen plavog (MP, 10 µg) datog intracerebroventrikularno pre hemijskog konvulziva pentilentetrazola (PTZ, 80 mg/kg), primenjenog intraperitonealno. Pacovi su posmatrani četiri minuta posle davanja PTZ-a, posle čega su žrtvovani i u neprečišćenoj mitohondrijskoj frakciji prednjeg mozga, hipokampusa i strijatuma određivani su parametri oksidoreduktivne ravnoteže. Rezultati. Posle primene PTZ-a, konvulzivni odgovor (distonija prednjih nogu - DPN, generalizovane klonične - GKK i generalizovane kloničnotonične konvulzije - GKTK) bio je ispoljen kod svih životinja, kao i statistički značajno sniženje lipidne peroksidacije u kori prednjeg mozga i strijatuma, i povećanje aktivnosti superoksid dizmutaze (SOD) u hipokampusu, u poređenju sa kontrolnom grupom (dobila fiziološki rastvor NaCl). Registrovani su antikonvulzivni efekti L-NAME koji nisu bili statistički značajni. U hipokampusu ovih životinja bila je snižena lipidna peroksidacija (p < 0,01 u poređenju sa kontrolnom grupom, p < 0,05 u poređenju sa životinjama koje su dobile PTZ), kao i aktivnost SOD u poređenju sa životinjama koje su dobile PTZ. Samo metilen plavo dovelo je do statistički značajnog smanjenja incidencije GKK I GKTK (DPN: p = 0,0513), produžilo je latentni period DPN, GKK i GKTK, a u svim ispitivanim strukturama mozga bila je povećana lipidna peroksidacija i smanjen nivo superoksidnog anjona. Svi klinički i biohemijski efekti izazvani primenom MP u potpunosti su odstranjeni primenom L-NAME 10 minuta pre davanja MP. Zaključak. Metilen plavo, dat samostalno pre PTZ, ispoljio je snažne antikonvulzivne efekte. Nestanak ovih efekata i izmenjeni biohemijski parametri u mozgovima pacova koji su pre MP dobili L-NAME, sugerišu da je NO uključen u efekte MP ispoljene na životinjskom modelu konvulzija izazvanih primenom PTZ-a.nul

Nitric oxide (NO) and an NMDA receptor antagonist in pentylenetetrazole-induced convulsions

Controversy about proconvulsant and anticonvulsant nitric oxide (NO) effects and the place of oxidative stress in convulsions, are still a matter of research. We investigated the interaction between 2-amino-5-phosphonovaleric acid (APV), a competitive N-methyl-D-aspartate (NMDA) receptor antagonist and Nw-nitro-L-arginine methyl ester (L-NAME), a nonselective nitric oxide synthase (NOS) antagonist, in pentylenetetrazole (PTZ)-induced convulsions. Pentylenetetrazole was applied to adult Wistar rats intraperitoneally (ip) in a single dose of 80 mg/kg, and L-NAME (10 µg/10 µl) or APV (20 µg/10 µl) intracerebroventricularly (icv), 30 and 10 minutes before PTZ, respectively. In the same manner, another group received both antagonists. Control animals were given 0.9% saline. Nw-nitro-L-arginine methyl ester exerted a weak anticonvulsant effect, preventing generalized clonic (GCC) and clonic-tonic convulsions (CTC) in 17% of cases. With APV protection against GCC and CTC was 100%, forelimb dystonia (FLD) was decreased in 33% of cases, and time to onset of all convulsive patterns was prolonged (p<0.05 to 0.01). All effects of APV, except in CTC, were reversed by L-NAME applied prior to APV. In APV-PTZ treated animals, superoxide anion content was increased in the forebrain cortex, striatum and hippocampus, without an overwhelmed antioxidative superoxide dismutase (SOD) defense system in the other treatments. When the APV-PTZ group was treated with L-NAME, both SOD activity and superoxide anion content were additionally decreased indicating that the NOS-NO system was involved in the metabolism of superoxide anions. It is suggested that clinical and biochemical effects of NO strongly depend upon the pretreatment and might lead to a wrong impression of NO contradictory activity.Kontroverzni nalazi o prokonvulzivnim kao i antikonvulzivnim efektima azot oksida (NO) i značaju oksidativnog stresa u konvulzijama, i dalje su predmet istraživanja. U konvulzijama izazvanim primenom pentilentetrazola (PTZ) ispitivali smo interakciju između 2-amino-5-fosfovalerinske kiseline (APV) kompetitivnog antagoniste N-metil-D-aspartat (NMDA) receptora i Nw-nitro-L-arginin metil estra (L-NAME), neselektivnog antagoniste azot oksid sintaze (NOS). Odraslim pacovima Wistar soja, PTZ je ubrizgavan intraperitonealno (ip) u jednoj dozi od 80 mg/kg. Ostale supstance, L-NAME (10 µg/10 µl) i APV (20 µg/10 µl), primenjivale su se intracerebroventrikularno (icv), i to L-NAME 30, a APV 10 minuta pre PTZ. Po istom vremenskom principu, jedna grupa dobila je oba antagonista, a kontrolna fiziološki rastvor NaCl. Nw-nitro-L-arginin metil estar ispoljio je slabo antikonvulzivno dejstvo, smanjujući incidenciju generalizovanih kloničnih (GCC) i klonično-toničnih konvulzija (CTC) za 17%. Za razliku od L-NAME, APV je sprečila nastanak GCC i CTC kod svih životinja (100%), a incidencija klonusa prednjih nogu (FLD) smanjena je za 33%. Istovremeno primenom APV produženo je vreme od aplikacije PTZ do pojave svih konvulzivnih tipova (p<.05 do 0.01). Primenom L-NAME pre APV, umanjeni su efekti APV, pri čemu je došlo do povećanja incidencije FLD i GCC za 16% odnosno 50%. U kori prednjeg mozga, strijatumu i hipokampusu, životinja koje su dobile APV+PTZ, došlo do povećanja koncentracije superoksidnog anjona. Aktivnost superoksid dizmutaze ne prati ovaj skok. Njen dodatni pad u grupi tretiranoj sa L-NAME pre APV+PTZ, ukazuje da je sistem NOS-NO uključen u metabolizam superoksidnog anjona. Dobijeni rezultati ukazuju da klinički i biohemijski efekti NO u velikoj meri zavise od prethodno primenjenih supstanci i promena izazvanih njima, što može da doprinose sticanju pogrešnog utiska o kontradiktornim dejstvima NO.nul

Antioxidative effect of nerve growth factor (NGF) in rat thalamus after quinolinic acid-induced neurotoxicity

Quinolinic acid (QA) produces a pattern of selective cell loss in the striatum, that closely mimics that of Huntington's disease (HD). The aim of this study was to investigate the antioxidative status in the thalamus after intrastriatal application of QA and the influence of nerve growth factor (NGF) on such neurotoxicity. Wistar rats were treated intrastriatally (coordinates: 8.4A, 2.6L, 4.8V), using a stereotaxic instrument. The first group was treated with QA (150 nmol/l). The second group was treated with QA, followed by NGF (4.5 mg/kg b.w). The control group was treated with 0.9 % saline solution. Seven days after the treatment, we found decreased superoxide dismutase (SOD) activity in mitochondrial fractions of the striatum of both groups. In the thalamus, SOD activity showed no differences. The content of superoxide anion increased in the striatum of QA- treated animals. It was decreased in both structures in the group that was treated with QA and NGF. In the QA+ NGF-treated group, we found increased glutathione peroxidase (GSHPx) and GSH, compared to the group that was treated with QA only, but these values were lower than in the controls. Thus, NGF showed beneficial effects on the oxido-reduction status in the striatum, and also in the thalamus, a structure that is separated from but tightly connected with the striatum.Hinolinska kiselina (HK) prouzrokuje takav selektivni gubitak ćelija u strijatumu, koji veoma dobro imitira onaj kod Huntingtonove bolesti. Cilj ovog istraživanja bio je da se ispita antioksidativni status u talamusu nakon aplikacije HK u strijatum i uticaj NGF na takvu neurotoksičnost. Wistar pacovi su tretirani intrastrijatno, pomoću stereotaksičnog instrumenta (koordinate: 8,4A, 2,6L, 4,8V). Prva grupa je bila tretirana HK (150 nmol/l). Druga grupa je bila tretirana HK, a nakon toga je dobila NGF (4.5 mg/ kg b.w). Kontrolna grupa je bila tretirana fiziološkim rastvorom. Sedam dana nakon tretmana, u mitohondrijskim frakcijama strijatuma, našli smo smanjenu aktivnost SOD u obema grupama. U talamusu, aktivnost SOD se nije promenila. Sadržaj superoksidnog anjona se povećao u strijatumu životinja koje su bile tretirane HK, a smanjio se u obema strukturama, u grupi koja je bila tretirana sa HK i NGF. U HK+ NGF-tretiranoj grupi, našli smo povećanu aktivnost GSHPx i GSH u odnosu na grupu koja je bila tretirana samo sa HK, ali su te vrednosti bile manje u odnosu na kontrolne. NGF je pokazao povoljne efekte na oksido-reduktivni status u strijatumu, ali takođe i u talamusu, strukturi koja je odvojena, ali veoma blisko povezana sa strijatumom.nul

Effect of L-NAME on AlCl3-induced toxicity in rat brain

The present experiment was carried out to determine the effectiveness of nitric oxide synthase (NOS) inhibitor (L-NAME) in elevating the toxicity of AlCl3 on nitrite concentration and acetylcholine esterase activity of Wistar rats. Animals were killed 10 min and 3 days after the treatment and the forebrain cortex and striatum were removed. The results show that AlCl3 exposure promotes oxidative stress in different neural areas. The biochemical changes observed in neuronal tissues show that aluminium acts as a pro-oxidant, while NOS inhibitor exerts as antioxidant action in AlCl3-treated animals. In the present study, active avoidance learning was significantly impaired after AlCl3 injection, while pretreatment with L-NAME prevented the behavioural deficits caused between the 8th and 12th day after intrahippocampal application of neurotoxin. Our data suggest that aluminium may cause learning and memory deficits, while the treatment with L-NAME may decrease the oxidative stress and prevent learning and memory deficits caused by AlCl3.U eksperimentu je ispitivana efikasnost inhibitora azot oksid sintaze (NOS)- L-NAME na toksičnost AlCl3 i određivana koncentracija nitrita i aktivnost acetilholin esteraze kod Wistar pacova. Životinje su dekapitovane 10 minuta ili 3 dana nakon tretmana i izolovani su kora prednjeg mozga i strijatum. Rezultati ukazuju da AlCl3 pokreće oksidativni stres u različitim regionima mozga. Biohemijske promene opisane u neuronskom tkivu ukazuju da aluminijum deluje kao prooksidans, dok inhibitor NOS ima antioksidativno dejstvo kod životinja tretiranih AlCl3. Reakcija aktivnog izbegavanja je bila znatno poremećena nakon aplikacije AlCl3, dok se davanjem L-NAME sprečavaju poremećaji ponašanja uzrokovani između 8. i 12. dana posle intrahipokampusne primene neurotoksina. Naši rezultati ukazuju da aluminijum može dovesti do smetnji u procesima učenja i pamćenja, dok tretman sa L-NAME smanjuje oksidativni stres i sprečava promene u učenju i pamćenju uzrokovane AlCl3.nul

Influence of NG-nitro-L-arginine methyl ester on clinical and biochemical effects of methylene blue in pentylenetetrazole-evoked convulsions

Background/Aim. Despite years of research in a number of experimental models the question whether nitric oxide (NO) and methylene blue (MB) have pro- or anticonvulsant effects remains to be fully resolved. Methods. In adult Wistar rats the influence of a nonselective inhibitor of nitric oxide synthase NG-nitro-L-arginine methyl ester (LNAME, 10µg) on clinical and biochemical effects of MB (10µg) given before the intraperitoneally administered chemical convulsant pentylenetetrazole (PTZ, 80 mg/kg) was examined. MB and L-NAME were applied intracerebroventricularly. PTZ application was followed by a 4- minute observation time, after which rats were sacrificed and elements of oxido-reductive balance were measured in a crude mitochondrial fraction of forebrain cortex, hippocampus and striatum. Results. Convulsive responses (forelimb dystonia - FLD, generalised clonic- and clonic-tonic convulsions - GCC and GCTC respectively) were observed in all rats received PTZ, together with significantly decreased lipid peroxidation in the forebrain cortex and striatum and increased superoxide dismutase activity in the hippocampus, in comparison to controls (saline treated). It was registered anticonvulsant effects of L-NAME pretreatment. However, these effects were insignificant. In the hippocampus of these animals there was decreased lipid peroxidation (p < 0.01, p < 0.05 vs saline-treated and PTZ-treated rats, respectively) and reverted PTZ-induced increase of superoxide dismutase activity. But MB individually pretreatment significantly decreased the incidence of CTCs and GCCs (FLD: p = 0.0513), prolonged the convulsive latent time for FLD, GCTCs and GCCs, in all the examined brain regions increased lipid peroxidation and decreased the level of superoxide anion. Administration of L-NAME 10 minutes before MB reverted all MB-evoked clinical and biochemical effects. Conclusion. Methylene blue applied individually before PTZ has strong anticonvulsant effects that were eliminated by L-NAME pretreatment. These effects and changed biochemical parameters in the brains of animals treated by L-NAME before MB in comparison to MBtreated group suggest involvement of NO in MB's effects in the animal model of PTZ-evoked convulsions.Uvod/Cilj. I pored višegodišnjeg istraživanja na različitim eksperimentalnim modelima, nije potpuno odgovoreno na pitanje da li azot-oksid (NO) i metilen plavo (MP) deluju konvulzivno ili antikonvulzivno. Metode. Na odraslim pacovima Vistar soja ispitivan je uticaj NG-nitro-L-arginin metil estra (L-NAME, 10 µg), neselektivnog inhibitora azot oksid sintaze, na kliničke i biohemijske efekte metilen plavog (MP, 10 µg) datog intracerebroventrikularno pre hemijskog konvulziva pentilentetrazola (PTZ, 80 mg/kg), primenjenog intraperitonealno. Pacovi su posmatrani četiri minuta posle davanja PTZ-a, posle čega su žrtvovani i u neprečišćenoj mitohondrijskoj frakciji prednjeg mozga, hipokampusa i strijatuma određivani su parametri oksidoreduktivne ravnoteže. Rezultati. Posle primene PTZ-a, konvulzivni odgovor (distonija prednjih nogu - DPN, generalizovane klonične - GKK i generalizovane kloničnotonične konvulzije - GKTK) bio je ispoljen kod svih životinja, kao i statistički značajno sniženje lipidne peroksidacije u kori prednjeg mozga i strijatuma, i povećanje aktivnosti superoksid dizmutaze (SOD) u hipokampusu, u poređenju sa kontrolnom grupom (dobila fiziološki rastvor NaCl). Registrovani su antikonvulzivni efekti L-NAME koji nisu bili statistički značajni. U hipokampusu ovih životinja bila je snižena lipidna peroksidacija (p < 0,01 u poređenju sa kontrolnom grupom, p < 0,05 u poređenju sa životinjama koje su dobile PTZ), kao i aktivnost SOD u poređenju sa životinjama koje su dobile PTZ. Samo metilen plavo dovelo je do statistički značajnog smanjenja incidencije GKK I GKTK (DPN: p = 0,0513), produžilo je latentni period DPN, GKK i GKTK, a u svim ispitivanim strukturama mozga bila je povećana lipidna peroksidacija i smanjen nivo superoksidnog anjona. Svi klinički i biohemijski efekti izazvani primenom MP u potpunosti su odstranjeni primenom L-NAME 10 minuta pre davanja MP. Zaključak. Metilen plavo, dat samostalno pre PTZ, ispoljio je snažne antikonvulzivne efekte. Nestanak ovih efekata i izmenjeni biohemijski parametri u mozgovima pacova koji su pre MP dobili L-NAME, sugerišu da je NO uključen u efekte MP ispoljene na životinjskom modelu konvulzija izazvanih primenom PTZ-a.nul

Nitric oxide (NO) and an NMDA receptor antagonist in pentylenetetrazole-induced convulsions

Controversy about proconvulsant and anticonvulsant nitric oxide (NO) effects and the place of oxidative stress in convulsions, are still a matter of research. We investigated the interaction between 2-amino-5-phosphonovaleric acid (APV), a competitive N-methyl-D-aspartate (NMDA) receptor antagonist and Nw-nitro-L-arginine methyl ester (L-NAME), a nonselective nitric oxide synthase (NOS) antagonist, in pentylenetetrazole (PTZ)-induced convulsions. Pentylenetetrazole was applied to adult Wistar rats intraperitoneally (ip) in a single dose of 80 mg/kg, and L-NAME (10 µg/10 µl) or APV (20 µg/10 µl) intracerebroventricularly (icv), 30 and 10 minutes before PTZ, respectively. In the same manner, another group received both antagonists. Control animals were given 0.9% saline. Nw-nitro-L-arginine methyl ester exerted a weak anticonvulsant effect, preventing generalized clonic (GCC) and clonic-tonic convulsions (CTC) in 17% of cases. With APV protection against GCC and CTC was 100%, forelimb dystonia (FLD) was decreased in 33% of cases, and time to onset of all convulsive patterns was prolonged (p<0.05 to 0.01). All effects of APV, except in CTC, were reversed by L-NAME applied prior to APV. In APV-PTZ treated animals, superoxide anion content was increased in the forebrain cortex, striatum and hippocampus, without an overwhelmed antioxidative superoxide dismutase (SOD) defense system in the other treatments. When the APV-PTZ group was treated with L-NAME, both SOD activity and superoxide anion content were additionally decreased indicating that the NOS-NO system was involved in the metabolism of superoxide anions. It is suggested that clinical and biochemical effects of NO strongly depend upon the pretreatment and might lead to a wrong impression of NO contradictory activity.Kontroverzni nalazi o prokonvulzivnim kao i antikonvulzivnim efektima azot oksida (NO) i značaju oksidativnog stresa u konvulzijama, i dalje su predmet istraživanja. U konvulzijama izazvanim primenom pentilentetrazola (PTZ) ispitivali smo interakciju između 2-amino-5-fosfovalerinske kiseline (APV) kompetitivnog antagoniste N-metil-D-aspartat (NMDA) receptora i Nw-nitro-L-arginin metil estra (L-NAME), neselektivnog antagoniste azot oksid sintaze (NOS). Odraslim pacovima Wistar soja, PTZ je ubrizgavan intraperitonealno (ip) u jednoj dozi od 80 mg/kg. Ostale supstance, L-NAME (10 µg/10 µl) i APV (20 µg/10 µl), primenjivale su se intracerebroventrikularno (icv), i to L-NAME 30, a APV 10 minuta pre PTZ. Po istom vremenskom principu, jedna grupa dobila je oba antagonista, a kontrolna fiziološki rastvor NaCl. Nw-nitro-L-arginin metil estar ispoljio je slabo antikonvulzivno dejstvo, smanjujući incidenciju generalizovanih kloničnih (GCC) i klonično-toničnih konvulzija (CTC) za 17%. Za razliku od L-NAME, APV je sprečila nastanak GCC i CTC kod svih životinja (100%), a incidencija klonusa prednjih nogu (FLD) smanjena je za 33%. Istovremeno primenom APV produženo je vreme od aplikacije PTZ do pojave svih konvulzivnih tipova (p<.05 do 0.01). Primenom L-NAME pre APV, umanjeni su efekti APV, pri čemu je došlo do povećanja incidencije FLD i GCC za 16% odnosno 50%. U kori prednjeg mozga, strijatumu i hipokampusu, životinja koje su dobile APV+PTZ, došlo do povećanja koncentracije superoksidnog anjona. Aktivnost superoksid dizmutaze ne prati ovaj skok. Njen dodatni pad u grupi tretiranoj sa L-NAME pre APV+PTZ, ukazuje da je sistem NOS-NO uključen u metabolizam superoksidnog anjona. Dobijeni rezultati ukazuju da klinički i biohemijski efekti NO u velikoj meri zavise od prethodno primenjenih supstanci i promena izazvanih njima, što može da doprinose sticanju pogrešnog utiska o kontradiktornim dejstvima NO.nul

Optimizacija mlevenja aktivne komponente i hidrofobizacija dobijenog sredstva za gašenje požara]

This work presents a grinding process of monoammonium phosphate (MAP) as an active component in a powder fire extinguisher (PFE). The aim was to determine the grinding time for reaching the optimal particle size of MAP necessary for permanent fire extinguishing. MAP grinding was performed by using a laboratory ceramic ball mill and a vibrating cup mill. The grinding process was controlled by sieving using a 100 µm sieve at precisely defined time intervals. The efficiency of a PFE depends on the share of the -100 µm fraction of the active component, which has to exceed 60 %. The optimal grain size with 64 % of fraction of particle size -100 µm was obtained after 33 min of grinding of ≈3000 µm mm grain size MAP by using a ball mill (single-stage grinding). In two-stage process, by grinding the same initial MAP sample (≈3000 µm) in the vibro mill for 10 min, powder with the upper limit grain size of 300 µm and the mean grain diameter of 120 µm was obtained. This sample with a reduced size was further ground in the ceramic ball mill yielding 67.5 % of the fraction of particle size -100 µm after 19 min. The total time of the two-stage grinding process was 29 min. By analyzing the grinding time of MAP required to get the lowest required share of the fraction of particle size -100 µm that provides the effectiveness of formed PFE it can be concluded that 64 % of this fraction was obtained after 33 min of single-stage grinding, while only after 26 min in the two-stage process. Thus, the grinding time was reduced by 7 min indicating certain energy savings. Stability and hydrophobicity of the obtained PFE were achieved by coating with magnesium stearate (MgSt) at the content of 2 % in a ball mill for 15 min. The coating was confirmed by the standardized procedure for verification of PFE hydrophobic properties in contact with water drops. To obtained PFE had component mass ratios of MAP:AS:CC:QS:MgSt=55:20:18:5:2 (AS-ammonium sulfate; CC-calcium carbonate, QS-quartz sand) and was further characterized by chemical and granulometric analyses. The fire extinguishing efficiency of the PFE was tested in controlled conditions, whereby fires were initiated by burning solid materials and flammable liquids. In both cases, immediate elimination of flames was achieved, thus proving the efficiency of the PFE obtained in this work for practical applications.U radu je prikazan postupak mlevenja monoamonijum fosfata (MAP) kao aktivne komponente u praškastom sredstvu za gašenje požara (SGP). Cilj je bio da se utvrdi vreme mlevenja MAP koje je potrebno za dobijanje optimalne granulacije za potpuno gašenje požara i eliminisanje plamena. MAP je mleven u laboratorijskom keramičkom mlinu sa kuglama i vibro mlinu sa prstenastim radnim elementima. Proces je kontrolisan prosejavanjem na situ 100 μm. Utvrđeno je da se mlevenjem granula MAP veličine ≈3000 μm u laboratorijskom mlinu sa kuglama optimalna krupnoća od 64 % frakcije čestica veličine -100 μm dobija nakon 33 min mlevenja. Za postizanje iste finoće proizvoda u dvostepenom mlevenju vreme je skraćeno na 26 min (10 min u vibro mlinu i 16 min u mlinu sa kuglama). Stabilnost i hidrofobnost SGP je postignuta oblaganjem magnezijum stearatom (MgSt) pri udelu od 2 % u mlinu sa kuglama u trajanju od 15 min. Efikasnost gašenja je testirana na poligonu u realnim uslovima. Na tačno određenom mestu za testiranje, u kontro-lisanim uslovima, izazvan je požar paljenjem čvrstih materijala i zapaljivih tečnosti. U oba slučaja je došlo do trenutne eliminacije plamena. Na taj način je potvrđena efikasnost formiranog SGP i mogućnost njegove upotrebe u praksi