Showing papers by "University of Zagreb published in 1994"

Response of the Adriatic Sea to the bora and sirocco forcing

Abstract: The response of the Adriatic shelf waters to dominant winter winds is analysed: the bora, which is a cold, katabatic wind blowing from the northeast; and the sirocco, which blows from the southeast and brings warm Mediterranean air. Currents and sea-level changes, caused by momentum exchange at the air-sea interface, are simulated using a three-dimensional numerical model. Numerical predictions are verified through comparison with data collected in the area. It is shown that the bora induces a rather complex response of the Adriatic Sea, with sea levels organized in several lows and highs and the current field dominated by the wind-curl effect. The currents are directed downwind under the bora maxima, upwind under the minima. Simulations of the bora-driven sea levels and currents are supported by results of in situ measurements carried out on the Adriatic shelf. Moreover, they are confirmed by an analysis of the Coastal Zone Color Scanner (CZCS) imagery, showing that during the bora episodes highly-productive Po-influenced waters extend from the river mouth in an offshore direction, due to advection by upwind currents. The sirocco piles up water in the North Adriatic and brings about the occurrence of storm surges along the northern shorelines. This process has been documented amply in the literature. According to the present model, the sirocco-driven currents are controlled by two different mechanisms: bottom slope, supporting the existence of a cyclonic and an anticyclonic gyre in the sea; and wind curl, which is a source of cyclonic vorticity in the basin. The data show that the sirocco may reverse the current usually found along the western coast, when the wind-forced current component becomes stronger than buoyancy-driven residual flow.

Children in war: A silent majority under stress

Abstract: To assess the amount of stress exposure and reactions among children following a war situation, two comparative groups of non-displaced (N = 64) and displaced children (N = 70) from Croatia were administered a modified version of the War Trauma Questionnaire as well as the Impact of Event Scale (IES). The results showed that a majority of the children had been exposed to armed combat, with displaced children significantly more exposed to destruction of home and school as well as to acts of violence, and loss of family members, than the non-displaced children. Regarding the IES scores, displaced children had significantly higher scores for the total score and for the intrusion and avoidance subscales. For girls the total score and intrusion score were significantly higher than for boys. Different exposure factors were significantly related to the IES scores, especially for the intrusion subscale of the IES.

Mitochondrial DNA sequence divergence among some west European brown bear ( Ursus arctos L.) populations. Lessons for conservation

Abstract: We used the polymerase chain reaction and nucleotide sequencing to study mitochondrial DNA (mtDNA) genetic variability of brown bears (Ursus arctos) belonging to some western European populations. Demographic decline and isolation have apparently shaped genetic variability within and between populations. Small relict bear populations were apparently monomorphic and fixed for different mtDNA haplotypes. Genetic relationships among mtDNA haplotypes suggested the existence of a phylogeographic structure. We discuss the possible roles of historical and demographic factors in determining the observed genetic patterns. The low genetically effective size of the studied brown bear populations points to risks of continuing future loss of gene diversity and increase in inbreeding. Artificial gene flow through restocking could alleviate inbreeding depression in small isolated brown bear populations, and mtDNA phylogeographic relationships may provide a framework for their genetic management.

Non-toxic organic zinc corrosion inhibitors in hydrochloric acid

Abstract: The efficiency of some substituted N-arylpyrroles as zinc corrosion inhibitors in hydrochloric acid was examined by electrochemical (d.c. and a.c.) and gravimetric methods. The influence of the structure and composition of a molecule on the inhibition characteristics was observed by investigation of the action of the functional group located on the pyrrole ring (-CHO) and at the ortho position of the benzene ring (-H, -Cl, -CH3). The results have shown that all the organic compounds investigated possess good inhibiting properties. In contrast to most commercial acid corrosion inhibitors, which are highly toxic and very hazardous products, substituted N-arylpyrroles are nontoxic compounds with good environmental characteristics.

Peptide motifs of HLA-A1,-A11,-A31, and-A33 molecules

Abstract: As a source of HLA-A molecules, the human B-cell line C1R (Alexander et al. 1990; Zemmour et al. 1992) transfected with the respective genes was used. C1R cells do not express HLA-A or -B molecules on their own, with the exception of small amounts of HLA-B35 (Zemmour et al. 1992). In addition, C1R cells express HLA-Cw4. C1R-A1 cells were a gift of R Romero, Lausanne; C1R-All (A*ll01), C1R-A31 (A*3101), and C1R-A33 (A'3302; Kato et al. 1993), each highly expressing the respective molecules, were produced at the University of Tokyo. HLAA'1101 and A'3101 genes were previously cloned from Japanese individuals and sequenced (data not shown). Transfectants were grown to about 1010 to 1011 cells in roller bottle tissue culture. HLA molecules were precipitated from detergent lysates of the cells, using solidphase bound antibodies specific for HLA-A, -B, -C, PA2.6 (Parham and Bodmer 1978), or W6/32 (Barnstable et al. 1978), as described (Falk et al. 1991). Precipitates were treated with trifluoroacetic acid to dissociate peptides, and the peptides were separated from the remaining material by reversed phase high-performance liquid chromatography, using the SMART system (Pharmacia, Freiburg, Germany),

The effect of supporting electrolyte on the electrochemical synthesis, morphology, and conductivity of polyaniline

Abstract: Electrochemical synthesis of polyaniline (PANI) was carried out under cyclovoltammetric conditions using H2SO4, HCl, HNO3, and HClO4 as supporting electrolytes. The observed different rate of PANI deposit growth depending on the acid in the solution has been explained on the grounds of a different degree of specific adsorption for particular anion. It has been found that morphology of the deposit depends greatly upon the anion present in the solution. Thus, PANI synthesized from the solution of oxyacids results in a dense sponge-like structure while PANI from the hydrochloric acid solution results in a spaghetti-like structure. The structure of the deposit influences the conductivity, being higher for a dense deposit from oxyacid solutions and three orders of magnitude lower in case of a deposit from hydrochloric acid solution. © 1994 John Wiley & Sons, Inc.

An attempt to screen asymptomatic women for ovarian and endometrial cancer with transvaginal color and pulsed Doppler sonography.

Abstract: Several screening procedures have been proposed to detect ovarian and endometrial cancer. However, none of them is sensitive and specific enough to be used in population-based screening programs. During our 5 year long study, 5013 asymptomatic women (44% premenopausal and 56% postmenopausal women) were scanned by transvaginal color and pulsed Doppler ultrasonography in an attempt to detect malignancy. These women had 404 adnexal cysts; 70 had resolved spontaneously on follow-up scans and 18 persisted. Another 316 sonographically benign cysts are still in the procedure of follow-up second scans. Of 5013 women, four women had stage I ovarian carcinoma and six had stage I endometrial carcinoma. There was one false-positive case encountered with an endometrioma. Only 14 women were subjected to major operative intervention; others underwent minor procedures based on the benign scan findings. No medical or surgical complications were reported. Transvaginal color Doppler ultrasonography, a noninvasive procedure, can detect ovarian and endometrial carcinoma in asymptomatic women and may be used as a screening procedure for these diseases.

Osteotomy for deformity of the radius. Computer-assisted three-dimensional modelling

Abstract: A computer-assisted method of preoperative planning was used to create virtual models of the deformed distal end of the radius after malunion of a fracture. By comparison with a similar model of the uninjured wrist, values were calculated for the angles and lengths to be corrected by osteotomy. Shifts of the distal fragment were analysed for 33 deformed wrists, 27 of which underwent corrective osteotomy and bone grafting. In more than half the cases there was dorsal or volar shift of 3 mm or more. The accuracy of the correction was measured by comparing the three-dimensional models before and after osteotomy with the model of the normal wrist. The volar and ulnar inclination angles of the articular surface of the radius and the radial length were regularly restored to normal.

Impedance spectroscopic study of aluminium and Al-alloys in acid solution: inhibitory action of nitrogen containing compounds

Abstract: The adsorption behaviour of triethanolamine (TEA) on aluminium, AlMgSi and AlZnMg alloys covered with naturally formed oxide films was investigated in 0.5 M NaCl solution, pH 1.3, by means of potentiodynamic and electrochemical impedance spectroscopy techniques. The results of polarization measurements show that in all cases the addition of TEA induces a decrease in the cathodic currents without affecting the anodic polarization behaviour, and, accordingly, TEA can be treated as a cathodic type inhibitor. The adsorption behaviour of TEA on the electrode surface follows a Frumkin isotherm with constants:a = 1.74,B = 18.41 dm3 mol−1. The results of impedance measurements presented in Nyquist plots show a high frequency capacitive loop related to the dielectric properties of the oxide film and a low-frequency inductive part which was determined by the faradaic process and attributed to the localized corrosion.

The fetus as a patient.

Abstract: This article highlights the concept, history and development of fetal medicine. The first attempts of fetal medicine date from the stone age and have continued throughout the medieval and modern ages. Attempts to influence fetal health and pregnancy outcome at first were purely theoretical and passive, limited by ignorance, fear, and religion. With the development of the medical sciences, the role of the obstetrician became more active. Today, not only obstetricians, but many other experts in the field of antenatal care as well, deal with the great number of medical and technological advances. The limitations arising today are mainly ethical. The main question that still has not been answered is to what extent the physician is allowed to interfere with the process of fetal development and pathology, based upon real fetal and maternal benefit. In order to answer this question and to coordinate many activities by different experts in this field, an international society antitled The Fetus as a Patient was formed in 1985. Croatian experts have played a leading role in this concept.

Renal vascular resistance in diabetic nephropathy : duplex Doppler US evaluation

Abstract: PURPOSE: To evaluate duplex Doppler sonography to assess renal vascular resistance (RVR) in diabetic patients. MATERIALS AND METHODS: Resistive indexes (RIs) and pulsatility indexes (PIs) were measured in intrarenal arteries of 144 patients with diabetes mellitus and 61 control subjects. RIs and PIs were compared for control subjects and patients with diabetic nephropathy and correlated with laboratory and clinical findings. RESULTS: In control subjects, the mean RI was 0.595 +/- 0.033 (standard deviation) and mean PI was 1.001 +/- 0.105. Elevated RIs and PIs accompanied progression of nephropathy. Statistically significant (P < .001) correlations were observed between both RI and PI and serum creatinine level, creatinine clearance rate, systolic and diastolic blood pressure measurements, and patient age. CONCLUSION: Doppler indexes reflect increased RVR in diabetic nephropathy and correlate with laboratory and clinical parameters, but RI and PI measurements offer no advantages over these parameters to pr...

Effects of atrazine on reproductive performance in the rat

Abstract: The effects of subacute exposure to atrazine on body weight, ovarian cycling, conception rate and the size of litters in Fischer strain rats were studied. An atrazine dose of 120 mg kg-1 body wt given p.o. daily for 7 days to both female and male rats caused statistically significant loss of body weight in both sexes during the period of treatment. After the cessation of treatment the body weight of female rats remained below control body weights at least for 2 weeks. In male rats the difference in body weights narrowed with time and reached control level 5 days after the last dose. Atrazine caused a significant increase in the relative weights of pituitary and prostate. Atrazine also transiently prolonged the oestrous cycle, characterized by extended vaginal dioestrus. As a result of disturbed ovarian cycling, the rate of successful mating decreased in the first week after treatment when both sexes were exposed or exposed females were mated with an unexposed male. No similar effect was observed when only the males were exposed. The size of litters did not differ significantly between experimental groups.

Identification of amino acid residues involved in the binding of Huperzine A to cholinesterases

Abstract: Huperzine A, a potential agent for therapy in Alzheimer's disease and for prophylaxis of organophosphate toxicity, has recently been characterized as a reversible inhibitor of cholinesterases. To examine the specificity of this novel compound in more detail, we have examined the interaction of the 2 stereoisomers of Huperzine A with cholinesterases and site-specific mutants that detail the involvement of specific amino acid residues. Inhibition of fetal bovine serum acetylcholinesterase by (-)-Huperzine A was 35-fold more potent than (+)-Huperzine A, with KI values of 6.2 nM and 210 nM, respectively. In addition, (-)-Huperzine A was 88-fold more potent in inhibiting Torpedo acetylcholinesterase than (+)-Huperzine A, with KI values of 0.25 microM and 22 microM, respectively. Far larger KI values that did not differ between the 2 stereoisomers were observed with horse and human serum butyrylcholinesterases. Mammalian acetylcholinesterase, Torpedo acetylcholinesterase, and mammalian butyrylcholinesterase can be distinguished by the amino acid Tyr, Phe, or Ala in the 330 position, respectively. Studies with mouse acetylcholinesterase mutants, Tyr 337 (330) Phe and Tyr 337 (330) Ala yielded a difference in reactivity that closely mimicked the native enzymes. In contrast, mutation of the conserved Glu 199 residue to Gln in Torpedo acetylcholinesterase produced only a 3-fold increase in KI value for the binding of Huperzine A.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanism of antifoaming action of simethicone

Abstract: The mechanism of the foam-inhibiting action of simethicone, mainly used against flatulence, has been studied. Its effect on foaming systems containing synthetic gastric juice and a surface-active substance (anionic surfactant, cationic surfactant, soap solution) was quantitated by measuring the surface tension, foam stability and initial foam density. The effect of simethicone on each of the examined systems was the result of the combination of two actions: the drainage of liquid from foam films and the rupture of relatively thick liquid films. The mechanism of these actions may be described as the liquid drainage followed by bridging of the liquid film by polydimethylsiloxane droplets, helped by hydrophobic silica particles also present in the antifoaming agent, leading to the rupture of the film surface and air escape.

Intrarenal duplex Doppler sonographic evaluation of unilateral native kidney obstruction.

Abstract: RIs were measured in intrarenal arteries in 66 kidneys of 33 examinees without renal impairment and in 42 kidneys of 21 patients with unilateral urinary obstruction. The mean RI in normal kidneys was 0.593 +/- 0.040. Patients with unilateral obstruction had a mean RI of 0.709 +/- 0.039 in obstructed kidneys and a mean RI of 0.591 +/- 0.033 in contralateral nonobstructed kidneys. Statistically significant differences have been noticed in the groups of normal versus obstructed kidneys (P < 0.001) and of obstructed versus contralateral nonobstructed kidneys (P < 0.001). The mean dRI was 0.118 +/- 0.034 in patients with unilateral obstruction, and it was 0.014 +/- 0.012 in examinees without renal impairment (P < 0.001). A comparison of RI values between the right and left kidneys in a patient with unilateral obstruction proved more useful than using a 0.7 RI cutoff value in a Doppler sonographic diagnosis of unilateral obstruction.

Scale-up on basis of structured mixing models: A new concept.

Abstract: A new scale-up concept based upon mixing models for bioreactors equipped with Rushton turbines using the tanks-in-series concept is presented. The physical mixing model includes four adjustable parameters, i.e., radial and axial circulation time, number of ideally mixed elements in one cascade, and the volume of the ideally mixed turbine region. The values of the model parameters were adjusted with the application of a modified Monte-Carlo optimization method, which fitted the simulated response function to the experimental curve. The number of cascade elements turned out to be constant (N = 4). The model parameter radial circulation time is in good agreement with the one obtained by the pumping capacity. In case of remaining parameters a first or second order formal equation was developed, including four operational parameters (stirring and aeration intensity, scale, viscosity). This concept can be extended to several other types of bioreactors as well, and it seems to be a suitable tool to compare the bioprocess performance of different types of bioreactors. © 1994 John Wiley & Sons, Inc.

Different Distributions of Glycosphingolipids in Mouse and Rabbit Skeletal Muscle Demonstrated by Biochemical and Immunohistological Analyses

Abstract: The expression of neutral glycosphingolipids and gangliosides was investigated in mouse and rabbit skeletal muscle by means of biochemical and immunochemical techniques. Neutral glycosphingolipids from muscle of the inbred rabbit strain used in this study showed a simple TLC pattern, comprising mainly monohexosylceramide. In addition to this compound, lactosylceramide, lacto-N-neotetraosylceramide, globoside and Forssman GSL were detected in mouse muscle. The major ganglioside in both species was GM3; GM3 (Neu5Ac) and GM3(Neu5Gc) were found in a 3:1 ratio in mouse muscle, whereas the absence of GM3(Neu5Gc) is characteristic of rabbit muscle. As a general structural feature of all muscle GM3 gangliosides investigated, a C18 fatty acid and C18 sphingosine were the major components besides minor C22 and C24:1 fatty acids of the respective ceramide portions, as revealed by positive and negative ion FAB-MS. alpha 2-3 sialylated lacto-N-neotetraosyl-ceramide (sialylparagloboside) was expressed in both species, whereas the alpha 2-6 sialylated isomeric compound was found only in mouse muscle. Minute quantities of ganglio-series GM1, GD1a, GD1b, and GT1b were detected in muscles from both species. Glycosphingolipid expression could be confirmed immunohistochemically by examining transverse and longitudinal cryosections of skeletal muscle samples. The results provide the basis for the investigation of muscle specific glycosphingolipids that might modulate membrane protein functions in muscle.