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Activity of cat cerebellar neurons in penicillin epilepsy and amphetamine treatment
No full textThe discharge pattern of cerebellar Purkinje cells and fastigial neurons was studied after acute amphetamine treatment in immobilized cats, as well as during generalized penicillin-induced epilepsy. There was a marked reversible decrease in spontaneous firing rate of Purkinje cells and an increase in spontaneous firing rate of fastigial neurons after acute d-1 amphetamine administration (5 mg/kg, s.c.). The discharge pattern of Purkinje cells showed tendency towards inhibition, while the fastigial neurons showed less clear tendency towards disinhibition in the course of epilepsy induced by parenteral administration of penicillin (400.000-500.000 I.U./kg, i.m.). Moreover, acute amphetamine treatment (5 mg/kg, s.c.) performed after the development of penicillin-induced epileptic episodes elicited a prominent suppression of Purkinje cell discharges associated with a parallel increase in discharges of fastigial neurons. These results suggest that the changes in discharge rate of cerebellar corticonuclear neurons induced by amphetamine contribute to suppression of seizural activity in the feline model of generalized epilepsy
The association of 5' haptoglobin gene-flanking sequences with nuclear matrix proteins during the acute phase response
No full textHaptoglobin (Hp) is one of several plasma proteins ‚whose concentration increases aout three times during the acute phase response (1). Its gene activity is controlled primarily by the action of transcriptional mechanisms (6).
In the work we studied the changes in the binding potential of the rat Hp gene sequences in the vicinity of its cis-element (-165/-147) (4) to nuclear matrix proteins during acute inflammation induced by turpentine
Effects of diet and temperature on Morimus funereus larvae hemolymph cation concentrations
No full texthe effects of diet and different constant temperatures on hemolymph cation concentrations (Na+, K+, Mg2+, Ca2+) have been studied in Morimus funereus larvae collected from natural habitat, fed natural (oak or beech bark) or artificial diet, as well as in larvae reared from hatching on an artificial diet. In the hemolymph of larvae maintained under natural conditions Mg2+ was dominant, whereas Na+ concentration was very low. In their natural diets concentrations of Na+ and K+ were very low, while those of Ca2+ and Mg2+ were high. In larvae continuously reared on an artificial diet, hemolymph Mg2+ concentration was significantly decreased and Na+ concentration increased more than fourfold compared to the results obtained in oak‐fed larvae. Na+ and K+ are the dominant cations in the artificial diet. The concentrations of K+ and Ca2+ in the hemolymph of larvae fed natural or artificial diet are nearly identical, suggesting the existence of an internal regulatory mechanism in this insect for these cations. The hemolymph cation concentrations of M. funereus larvae are predominantly dependent upon the diet consumed, much less upon the environmental temperatures. The most stable concentrations of cations were observed in larvae continuously fed an artificial diet and exposed to different constant temperatures. There was much less stability in the hemolymph cation concentration in oak larvae fed either natural or artificial food after their transfer to constant temperatures. With respect to the response to the external factors studied, the most sensitive are the Na+ concentrations, the most stable seems to be K+
The effect of cortical lesion on systemic penicillin epilepsy in rats
No full textThere is a certain recovery of function following brain damage, due to neuronal plasticity. The experiments were performed in order to investigate the effects of cortical lesion on seizural activity in rats induced by systemic application of penicillin. The sensorimotor cortex was unilaterally removed in the lesioned animals, while the control animals were only sham operated or non-operated (before implantation of the electrodes). Seizural activity was recorded by means of electroencephalograms before and after penicillin treatment (1,000,000 I.U./kg, i.p). Testing of penicillin started at least 30 days after cortical lesion. Seizural activity was characterized by spike and wave complexes accompanied by vigilance reduction and sometimes by mild myoclonic jerks in both control and lesioned animals. The early period (about 2 h after penicillin administration) with appearance of the spike-wave discharges with relative increase of the mean total electroencephalogram powers as well as the succeeding period 2.5-5.5 h after penicillin administration) with maximum number of spike-wave discharges did not differ in the electroencephalogram of the control and lesioned animals. The late period of penicillin effect (from 6-11 h after penicillin administration) with frequent spike-wave discharges and still large mean total electroencephalogram powers was observed only in lesioned animals. It is concluded that a cortical lesion destabilizes the brain function in the rat model of epilepsy induced by parenteral administration of penicillin
Metabolic strategies of Morimus funereus larvae during thermal stress
No full text1. The system of responses in Morimus funereus larvae to the effect of temperatures, diets and type of environment have been studied with respect to metabolic changes and gain in body wt.
2. The temperatures provoke remarkable changes in metabolic parameters in the larvae from natural habitat and are dependent upon diet.
3. During the intermoult period of 6th instar larvae the temperature of 35°C provokes significant decreases in metabolic parameters at the beginning of the exposure, however after a 7 day exposure the metabolic parameters (except the midgut amylase) return to the control level.
4. It was concluded that the outcome of thermal stress in M. funereus larvae was dependent upon diet, developmental phase and type of environment
Vegetation auf der Avala
No full textAvala je uvek bila privlačan i pristupačan objekat za razne botaničke naučno-istraživačke radove. Međutim, većina radova koji su bili doskora izvođeni, imala je pretežno floristički karakter. Do danas nije objavljen nijedan fitocenološki rad o Avali, sem referata Lj. Borisavljević o hrastovim fitocenozama Avale, održanog na I Kongresu biologa Jugoslavije u Zagrebu, 1953 godine (3). Institut za ekologiju i biogeografiju započeo je još 1949. godine fitocenološka istraživanja šuma Avale, a 1951. i livada. Ova si istraživanja trajala sa prekidima sve do 1952. godine. U njima je obuhvaćen samo centralni deo Avale, u granicama: od poslednje autobuske stanice na zapadnoj strani, državnim putem Beograd-Kragujevac do mesta zv. "Lovački sastanak", zatim granicom šume na istočnoj strani sve do borovih kultura na severnoj strani Avale. Značaj fitocenoloških istraživanja na Avali leži pre svega u upoznavanju sa jednim delom vegetacije Srbije, koji je specifičan zbog posebnog istorijskog razvoja, kao i geografskog položaja koji danas zauzima. Zatim, na Avali je zastupljen veći broj šumskih fitocenoza koje su relativno dobro sačuvane i izražene, a u isto vreme pristupačne za višegodišnja stacionarna istraživanja. Sem toga, Avala danas predstavlja narodni park i popularno izletište Beograđana. U cilju što pravilnijeg gazdovanja šumama na Avali, neophopdna su prethodna fitocenološka istraživanja, čiji rezultati mogu biti od velike koristi lokalnoj šumarskoj praksi. Zajedno sa rezultatima fitocenoloških istraživanja Košutnjaka (Gajić, 4) i Fruške Gore (Janković-Mišić, 8), ovaj će rad dati osnovnu sliku šumskih fitocenoza šire okoline Beograda. U ovome radu hrastove fitocenoze opisala je Lj. Borisavljević, livadske R. Jovanović-Dunjić, a bukove i borove V. Mišić, asistenti Instituta za ekologiju i biogeografiju u Beogradu.Zbornik radova, Knjiga 6, Broj