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J Perić

Publications and source records attributed to J Perić.

13 recordsLinked to original sources
PubMed2006

A comparative study of ion exchange kinetics in zinc/lead-modified zeolite-clinoptilolite systems.

The kinetics of zinc and lead ions removal by modified zeolite-clinoptilolite has been investigated. The rate of the ion exchange process for lead ions is faster than for zinc ions, as well as the time needed to reach the equilibrium. The ion exchange capacity of zeolite of lead ions is doubly higher than that of zinc ions. Diffusion models according to the Vermeulen's approximation, the parabolic diffusion model and the homogeneous diffusion model have been tested with the experimental data of ion exchange for zinc and lead. For both systems examined, the best fit of the models proposed with the experimental data was shown by the Vermeulen's approximation and the homogeneous diffusion model with t-->t(infinity). The diffusion coefficients are calculated from kinetic models of lead ions they are of the order of 10(-6)cm(2)/min, constant for all examined initial concentrations and not dependent on time. The diffusion coefficients in the system of zinc ions is of the order of 10(-8)cm(2)/min, also independent of initial concentrations, but decreasing with time from the beginning of ion exchange to the equilibrium.

Algorithms↗
PubMed2005

Investigations of different kinetic models for zinc ions uptake by a natural zeolitic tuff.

The kinetics of uptake of zinc ions from aqueous solutions by natural zeolitic tuff has been investigated. Batch experiments at constant temperature and hydrodynamic conditions have been performed. A decrease in the initial zinc concentration in aqueous solutions prolongs the time needed for equilibrium. Various kinetic models including the film-diffusion model, the surface diffusion model and the heterogeneous diffusion model have been tested for the description of the experimental results of zinc concentration in the solution over time. Diffusion through the film and diffusion through the surface of the particle could be the rate limiting steps at the initial reaction time. However, the heterogeneous diffusion model seems to be the best model providing a satisfactory fitting of the experimental results from the beginning of the process to the point of equilibrium, particularly at lower initial zinc concentrations.

Kinetics↗
PubMed2004

Removal of zinc, copper and lead by natural zeolite-a comparison of adsorption isotherms.

An uptake of zinc (Zn), copper (Cu), and lead (Pb) from aqueous solutions by ion exchange on natural zeolitic tuff has been studied. The Croatian zeolite clinoptilolite from the Donje Jesenje deposit has been used as a natural ion exchanger. The efficiency of removal is higher for Pb and Cu than for Zn ions. Measured concentrations of Si in the liquid phase identify the detachment of the aluminosilicate structure during ion exchange in the presence of H(+) and OH(-) ions. The adsorption isotherm equations; Langmuir-Freundlich, Redlich-Petersen, Toth, Dubinin-Radushkevich, modified Dubinin-Radushkevich, and Lineweawer-Burk were derived from the basic empirical equations, and used for calculation of ion exchange parameters. The best fitting of experimental results to the proposed isotherms was observed in models that assume that ionic species bind first at energetically most favorable sites, with multi-layer adsorption taking place subsequently.

Adsorption↗
PubMed2003

Interaction of the zeolitic tuff with Zn-containing simulated pollutant solutions.

The possibility of removing Zn2+ cations from wastewater by ion exchange using natural zeolites as exchangers has been investigated. The process of binding of zinc ions into zeolite structure has been established by several reaction mechanisms as a fast chemical reaction of ion exchange, accompanied by slower adsorption of different ionic species and possible precipitation or coprecipitation with the zeolite structure. The physicochemical phenomena such as hydrolysis and dissolution of surface layers are the result of interaction of zeolite with hydrogen or hydroxyl ions from the solution. Complexation of OH- with Zn2+ to form the zinc-hydroxy species strongly depends on pH value and affect the uptake mechanism as to lower dissolution of surface aluminosilicate layers. Structure imperfections as a surface property of mineralogical nonhomogeneous zeolitic grains can lead to formation of sorption surface sites with different energy, which affects the nonuniform distribution of different zinc species adsorbed. It is particularly possible in zeolitic tuff samples with relatively high content of aluminosilicates as minor mineralogical components, which is characteristic of Croatian deposits.

Journal Article↗
PubMed1999

Effect of different daily doses of gizzerosine on the serum 1,25-dihydroxycholecalciferol concentration in laying hens.

Five groups of laying hens were treated with different gizzerosine doses (0, 2.5; 5.0; 7.5; 10.0 mg/kg/body weight of gizzerosine) daily over a 21-day period to determine the serum concentrations of 1.25-dihydroxycholecalciferol (1,25(OH)2D), total calcium, inorganic phosphorus and magnesium. Blood samples were taken on days 7, 14, and 21 of the experiment. The concentration of 1,25(OH)2D remained unchanged after day 7 in the gizzerosine-treated birds compared to the control group. After 14 days, it was significantly lower in the birds receiving. gizzerosine, compared with the control group. On day 21, 1,25(OH2)D concentrations were also significantly decreased in all 4 gizzerosine-treated groups compared with the control hens. The serum total calcium, inorganic phosphorus and total magnesium concentrations varied significantly, but irregularly, during the period of the study.

Animals↗
PubMed1999

Effects of cimetidine on broiler fattening and on stress-induced gizzard erosion in chicken.

The work describes the effects of cimetidine on stress-induced gizzard erosions (Experiment A) and the influence of the long-term application (42 days) of the same drug on weight gain and feed consumption during broiler fattening (Experiment B). For Experiment A, 60 male, three-day-old chicks were divided into two groups: C (n = 30)--control chicks treated with 0.5 ml saline; CIM (n = 30)--chicks treated with cimetidine in a dose of 5 mg/kg body weight (b. w.) intragastrically. All chicks were stressed using a modified water-immersion stress method according to which the chicks, after 24 h of feed deprivation, were immersed in tap water (17 degrees C) for a few seconds. Under chloroform anaesthesia ten chicks from each group were killed 1, 2 and 3 h after the stressing. The morphometric analysis of gizzard erosion (GE) and histopathological examinations of gizzards were performed for each chick. In Experiment B, 32 one-day-old broilers of both sexes were used. The control group was untreated (n = 16) while the CIM group (n = 16) was fed the same diet supplemented with 10 mg of cimetidine per kilogram of feed throughout the fattening period (42 days). The results of Experiment A showed decreased mean length of the GE in the cimetidine-treated birds as compared with the GE lesions of the controls. In Experiment B, the treated chicks had reduced liveweight (1835.1 g), carcass weight (1474.6 g) and increased feed consumption (2115 g of feed per kilogram of weight gain) compared to the controls in which the same parameters were 1898.5 g, 1574.2 g and 1797 g, respectively. The results show that while stress-induced GE of chicks can be medicated pharmacologically, long-term application of the same substance impairs the results of fattening.

Animals↗
PubMed1998

A novel pentadecapeptide, BPC 157, blocks the stereotypy produced acutely by amphetamine and the development of haloperidol-induced supersensitivity to amphetamine.

BACKGROUND: A novel gastric pentadecapeptide, BPC 157, has been shown to attenuate different lesions (i.e., gastrointestinal tract, liver, pancreas, somatosensory neurons). This suggests an interaction with the dopamine system. When used alone, BPC 157 does not affect gross behavior or induce stereotypy. METHODS: We first investigated the effect of pentadecapeptide BPC 157 on stereotypy and acoustic startle response in rats, given as either a prophylactic (10 micrograms/kg i.p.) or therapeutic (10 ng/kg i.p.) regimen, with the dopamine indirect agonist amphetamine (10 mg/kg i.p.). RESULTS: There was a marked attenuation of stereotypic behavior and acoustic startle response. When the medication was given at the time of maximum amphetamine-induced excitability, there was a reversal of this behavior. A further focus was on the effect of this pentadecapeptide on increased climbing behavior in mice pretreated with the dopamine antagonist haloperidol (5.0 mg/kg i.p.), and subsequently treated with amphetamine (20 mg/kg i.p. challenge 1, 2, 4, and 10 days after haloperidol pretreatment). This protocol is usually used for the study of behavioral supersensitivity to the amphetamine stimulating effect. CONCLUSIONS: An almost complete reversal was noted when pentadecapeptide was coadministered with haloperidol. Together, these data provide compelling evidence for the interaction of pentadecapeptide BPC 157 with the dopamine system.

Amino Acid Sequence↗
PubMed1997

Pentadecapeptide BPC 157, cimetidine, ranitidine, bromocriptine, and atropine effect in cysteamine lesions in totally gastrectromized rats: a model for cytoprotective studies.

A superior effectiveness in various lesion assays was noted for the novel pentadecapeptide BPC 157, originated from human gastric juice protein (BPC) and claimed to be a cytoprotective agent. From this viewpoint, as a previously untreated experimental improvement to create an acid-free environmental for cytoprotection studies, total gastrectomy was done 24 hr before the ulcerogenic procedure. In the absence of stomach and gastric acid, the damaging effects of cysteamine (400 mg/kg subcutaneously, death 24 hr thereafter), to date thought to be an acid-related duodenal ulcerogen, and the BPC 157 cytoprotective effect (10 microg or 10 ng/kg intraperitoneally) were further challenged. BPC 157 was compared with reference agents [cimetidine (50), ranitidine (10), omeprazole (10), bromocriptine (10) and atropine (10) (mg/kg intraperitoneally, 1 hr before cysteamine] known to be also cytoprotective. In naive rats, with intact stomach, all of them showed a strong beneficial effect. Interestingly, in gastrectomized animals, the application of BPC 157 or the reference agents before cysteamine significantly prevented the otherwise severe duodenal lesion development noted in the control gastrectomized cysteamine rats. In groups without cysteamine, no lesions were noted (laparotomy, gastrectomy only, 24 or 48 hr postsurgical period), nor was lesion potentiation seen in cysteamine-treated laparotomized animals. In summary, these findings--equal damaging effect of cysteamine and equal protection of pentadecapeptide BPC 157 and reference agents in gastrectomized and rats with intact stomach--seem to be particularly relevant for a cytoprotective viewpoint. Without a stomach, the cysteamine damaging effect was convincingly defined as an essential gastric acid-independent injury (analogous to ethanol gastric lesions). Likewise, a high "cytoprotective capacity," apparently acid independent, common for all tested agents (novel pentadecapeptide BPC 157, cimetidine, ranitidine, omeprazole and atropine) could be clearly stressed.

Animals↗
PubMed1997

Brain-mediated protective interactions of histaminergic H2 and dopaminergic systems in rats.

Pretreatment with dopamine agonists (bromocriptine 2.5, L-dopa 2.5, apomorphine 0.05 mg/kg i.p.) and a histamine H2 receptor antagonist (cimetidine 50.0 mg/kg i.p.) was found to greatly reduce the haemorrhagic gastric lesions induced by 15-min pylorus ligation in rats. On the other hand, pretreatment with dopamine antagonists (haloperidol 5.0, sulpiride 1.0, domperidone 5.0 mg/kg i.p.) significantly aggravated these lesions. Cimetidine markedly diminished the ulcerogenic effect of haloperidol but not that of domperidone, suggesting a brain-mediated site for the protective interaction of cimetidine and dopamine systems.

Animals↗
PubMed1996

[Chlamydia urethritis in nephrologic practice].

Chlamydia trachomatis is an ubiquitous bacterium, strictly intracellular organism. The D-K serovars urethritis, cervicitis, endometritis, salpingitis, periappendicitis and perihepatitis, in women, urethritis, prostatitis, epididymitis and Reiter's syndrome in 1-2% of cases in men. Sterility is the most serious complication in both sexes. Chlamydial infections are sexually transmitted diseases, often asymptomatic, prone to recurrences. Cure occurs only when both sexual partners are treated simultaneously. We treated 40 patients, 24 women and 16 men, from 1991-1994, who presented in nephrologic offices with symptoms of chlamydial urethritis. Detection of Chlamydia trachomatis was performed by direct fluorescent antibody stain. All patients had positive urethral swab, six women had chlamydial cervicitis too, one man had Reiter's syndrome, one man orchiepididymitis, and five men prostatitis. Optimal therapy for Chlamydia trachomatis infections consists of a 10-14 day regimen of quinolone, of tetracycline, and macrolides. We used sulfonamide rarely. Because of very serious sequelae of initial infection with Chlamydia trachomatis, every patient with urethritis should be examined by urethral swab for Chlamydia testing. Both partners should be examined and treated simultaneously.

Adult↗
PubMed1995

Children's experience of a parent's chronic illness and death.

Five dependent young people who had experienced the chronic illness and death of a parent were asked to reflect on the meanings of their loss. The most important of the eight themes revealed by analysis of the data were the interviewees' emotional upheavals and the shock of being forced to face the realities of illness and death. During the illness phase, the participants had felt powerless and isolated. Through appropriate goodbyes and acceptance of their situation, the participants had identified the meaning and ongoing nature of loss and had resolved their feelings. They also acknowledged that a positive outcome of loss was that their self-esteem had increased as they identified and drew on their inner strengths.

Adaptation, Psychological↗
PubMed1995

Effects of histamine on gizzard erosions and on the activity of selected enzymes in chickens.

Dose- (5, 10 and 15 mg/kg body mass) and time-dependent (2, 6, 12 and 24 h after treatment) effects of histamine on gizzard lesions and serum AST, ALT and CK activities of chickens are reported. Morphometric results and histopathological examination revealed that the most effective histamine dose which induced severe gizzard lesions was 10 mg/kg b.m., especially 2, 6 and 12 h after administration. No difference from the control values was found after 24 h. That dose also induced an elevation of serum enzyme (AST, ALT, CK) activities, which was most expressed for the activity of ALT.

Alanine Transaminase↗