Radoslav K Andjus's research while affiliated with University of Belgrade and other places

Publications (30)

Article
At low ambient temperatures some small mammals drastically reduce their body temperature and enter a state of dormancy known as hibernation. They exhibit endogenous rhythms of heterothermy/homeothermy and body mass fluctuations with the period close to one year. At high ambient temperature only body mass cycling is expressed for almost one year as...
Article
Several classes of second-order retinal neurons have been studied electrophysiologically in European eel (Anguilla anguilla) from two different localities, Lake Seliger in Russia and the coastal waters of the Adriatic Sea in Montenegro. The majority of L-horizontal cells (68 explored) had both rod and cone inputs, an uncommon phenomenon among teleo...
Article
The characteristics of glass eel migration at the mouth of river Bojana have been investigated by seasonal field studies from February to April 1998. Samples were collected by two fyke nets, one on each riverside, for 12 hours each night. A total of about 3,300 individuals were caught. In this work we present the results obtained from three success...
Article
In the past, the results of experiments on the time course of concentration changes of adenylates, phosphocreatine, and free creatine in muscle appeared compatible with an equilibrium hypothesis involving only the Lohmann and the myokinase reactions. Other reports, however, denied the applicability of the equilibrium hypothesis to the same tissue....
Article
Glucose conversion by brain synaptosomes can be regarded as a special case of intrinsic kinetic properties of the enzyme substrate system. Temperature modulation of apparent K(m) for this process can be described with our kinetic model. Using experimental data and the kinetic model, the minimal K(m) value for glucose conversion in ground squirrel s...
Article
Scotopic electroretinogram of dogfish shark (Scylliorhinus canicula) and eel (Anguilla anguilla) is characterized by a negative off-response, changing in sign under photopic condition. It increased under the effect of increased background illumination, but its amplitude never exceeded that of the b-wave. On the other hand, dark-adapted electroretin...
Article
The remarkable time-resolution enhancement by deep lethargic hypothermia (15 degrees C rectal temperature, "cold narcosis," "anesthesia by internal cold") of metabolic events in the rat brain after oxygen deprivation has been exploited to monitor metabolic changes by in vivo (31)P-NMR. A correlation was established between the bioenergetic status o...
Article
One-minimum U-shaped temperature profiles of the dissociation constant (K(m)) have been observed experimentally with a variety of enzyme-substrate (E-S) systems. The increase of E-S affinity with falling temperature ("positive thermal modulation of affinity"), which opposes the cold-induced reduction in catalytic velocity, has been often interprete...
Article
In vitro binding of a steroid hormone (triamcinolone acetonide) to hepatic glucocorticoid receptors was studied in liver cytosols prepared from untreated control rats and rats sacrificed after being exposed in vivo to whole body hyperthermia (41 or 42°C). Positive temperature modulation of glucocorticoid–receptor affinity (decrease of affinity with...
Article
In view of the use of synthetic propentofylline (PPF) as a protective agent in brain ischemia, its possible side effects on vision capacities have been explored by electroretinography in comparative experiments with theophylline. We used eyecup preparations of small-spotted dogfish sharks and of European eels, particularly suitable for long-lasting...
Chapter
In the presence of saturating glucose concentrations, Arrhenius plot for glucose oxidation in the ground squirrel synaptosomes showed no discontinuity, while a sharp break was present when rat synaptosomes were used. The addition of 2,4-dinitrophenol (DNP), a potent uncoupler of oxidative phosphorylation, resulted in an increase of glucose oxidatio...
Chapter
The time course of the specific binding of triamcinolone acetonide (a synthetic glucocorticoid) to its cytoplasmic receptor (rat and ground squirrel liver cytosol preparations) has been recorded at a series of incubation temperatures, from 0 to 37°C. Experimental results were fitted with a theoretical model accounting for the temperature dependence...
Chapter
Body mass and hibernation/activity cycles have been measured in laboratory born European ground squirrels (Spermophilus citellus) during their entire life spans (up to 9.2 years). Effects of entrainment were tested applying forced square-wave cycles of environmental temperature, with alternating heat (30°C) and cold phases (7°C or 15°C), and with 1...
Article
Several classes of second-order neurons have been electrophysiologically explored in immature European eels (Anguilla anguilla) from two distant and ecologically different localities (in Russia and Yugoslavia). The majority of L-horizontal cells (58 explored) had both rod and cone inputs, an uncommon phenomenon among teleosts. Spectral sensitivity...
Article
Full-text available
Although differences in visual pigments between developmental stages of the European eel are well known, the expected differences in spectral sensitivity have not been demonstrated at the electrophysiological level. In fact, one past electroretinographic study led to the conclusion that in eels there is no change in scotopic sensitivity, with incre...
Article
Full-text available
About 10000 huchen larvae, obtained by artificial spawning, were introduced on 28 May 1995 into the River Tresnjica, a tributary to the River Drina, using procedures applied routinely by local fishing associations. During next two months, only 33 fry were caught in the river. Nevertheless, valuable information has been obtained for the first time o...
Article
Using 3H-labelled triamcinolone acetonide (3HTA, synthetic steroid hormone), it was shown that the in vitro time course kinetics of thermal activation of 3HTA-receptor complexes exhibited the same temperature dependence in liver cytosols prepared from hibernating ground squirrels (Spermophilus citellus) as in cytosols from the rat. When 3HTA was in...
Article
In view of a possible beneficial action of some of the xanthine derivatives in brain ischemia or anoxia, metabolic effects of synthetic propentofylline (3-methyl-[5′ oxohexyl]-7-propyl-xanthine) have been studied in multiple-dose experiments with suspensions of rat brain synaptosomes incubated at various temperatures. The rate of D-[14C] glucose co...
Article
Developing male rats were treated chronically with bromocriptine (BR, 3 mg/kg b.w. daily) to maintain severe hypoprolactinaemia throughout postnatal development. This treatment induced a precocious increase in Leydig cell numbers per testis and caused substantial, but age-dependent, modifications of the androgenic responsiveness of incubated hemi-t...
Article
Contrary to earlier views on the inability of naloxone to affect androgen variables by way of general circulation, systemically applied naloxone (2.5 mg/kg body weight, single i.p. or i.v. injection) has been shown to rapidly induce (within an hour) a significant fall (-35.7% on the average) of the concentration of serum androgen (testosterone and...
Article
In immature male rats, receiving daily injections of bromocriptine (3 mg/kg bw), serum prolactin (Prl) remains low throughout development. In such hypoprolactinaemic males androgen variables are affected: a) the normally low pre-pubertal serum androgen (testosterone, dihydrotestosterone-T, DHT) is considerably increased, in correlation with a preco...
Article
Developmental patterns of serum levels of androgens and of the luteinizing hormone (LH) were studied comparatively in: i) long-term hyperprolactinemic (LT) immature male rats bearing ectopic pituitary grafts since the age of 21 days and examined at weekly intervals thereafter; and ii) in short-term hyperprolactinemic (ST) males grafted at several p...

Citations

... The effect of prolactin on the sex accessory tissues was demonstrable in the absence of testicular or adrenal steroids (Negro-Vilar et al., 1977). Conversely, the administration of bromocriptine, a dopamine (DA) agonist, prior to puberty, lowers serum prolactin, decreases circulating androgen levels, and decreases accessory gland development (prostate, seminal vesicles), depending on the time and duration of exposure (Kovacevic et al., 1982;Suescun et al., 1985). Similarly, endogenous opioid peptides have a stimulatory influence on prolactin secretion (Hou and Voogt, 1999). ...
... The choice of a low pyruvate concentration (0.1 mM) used for our studies of temperature effect on LDH activity was supported by the work with brain synaptosomes, where the authors established that low concentration of substrate had profound influence on the rate of the reaction as a function of temperature (Marjanovic et al. 2000). Besides, the intracellular concentrations of the substrate were reported to be close to the Km (Somero 1978) and in the trout, it was determined that this pyruvate concentration was 0.11 mM (Hochachka and Somero 1984). ...
... The b-wave, the most prominent electroretinogram (ERG) wave, is a good indicator of spectral sensitivity in fish, although it only indirectly reflects responsiveness of photoreceptors (Andjus et al. 1983(Andjus et al. , 1998Nussdorf and Powers 1988;Easter and Hamasaki 1973;Saszik and Bilotta 1999). Until this study, it was considered true for all fish species except carp and goldfish, which possess rod photopigments with k max around 520 nm, because their peak spectral sensitivity based on b-wave is broader and shifts toward to the red part of the spectrum (Nussdorf and Powers 1988;Easter and Hamasaki 1973;Saszik and Bilotta 1999). ...
... The small-spotted dogfish shark is a one of the most abundant elasmobranch fishes in the south Adriatic (Andjus et al. 1998) and is easily kept in captivity, in cold-water recirculation systems. The dogfish shark is a rhodopsin possessing marine species with a rod dominated retina containing a single layer of photoreceptors indicated electrophysiologically by Ripps (1970, 1971), and hystologically by Bozzano et al. (2001), and with a rodcone ratio estimated to be >100 : 1 by Ashmore and Falk (1980). ...
... PPF itself has been shown to induce hypothermia (Kano et al., 1994), and some of our previous experiments indicated that the protective energy-sparing role of PPF in brain ischemia can be strongly potentiated by hypothermia (Andjus et al., 1988). In view of such a coupled application (PPF and low body temperature), our present experiments were designed to check the effects of the association of PPF and low temperature on ERG potentials. ...
... Maximum life span is 4 years for males and 6 years for females (Hoffmann et al. 2003a), but may be . 9 years in captivity (Andjus et al. 2000). Disappearance rates during the active season are severalfold higher than overwinter mortality, and may lead to the complete loss of a sex and age class (Millesi et al. 1999b). ...
... In contrast to body weight, body length variations were significantly lower, indicating a more even increase in individual body length. The body of the huchen is very elongated, which can be seen from the research of Nikcevic et al. (1998) which stating that the catch of a four-month-old huchen fry, which was released into the river after swimming in a hatchery, determined an average total body length of 58.95 ± 2.33 mm and an average body weight of 2.07 ± 0.14 g. ...
... It is, therefore, a priori likely that temperature cycles, even if they are internalized as in homeotherms, have functional implications. Indeed, this notion is supported by demonstrations that temperature modulates a variety of physiological and behavioral functions ranging from glucocorticoid receptor binding (Zivadinovic et al., 2001) to complex executive cognitive functions as assessed using the Tower of London task (Van Someren and Raymann, unpublished observations). The present paragraph discusses some recent findings on how body temperature cycles affect daytime and nocturnal functions relevant for human aging. ...
... The effectiveness of behavioral reinforcement by hiding into a shelter tube means that this training method can be applied in a variety of studies, because eels can survive for 1 year without food. Omura et al. (1997) observed cones in the retina of larvae of Japanese eels, and Byzov et al. (1998) reported yellow-sensitive and green-sensitive cones in European eels (A. anguilla). ...
... Interestingly, the detrimental effect of morphine on rNSCs neurosteroidogenesis was blunted during co-treatment with naloxone. Both opiate l-receptor-dependent and independent activity was previously observed when cells being exposed to naloxone [47,54]. One possible inhibitory effect of naloxone may be related to competing attachment to lreceptor same site co-administrated with morphine. ...