Showing papers by "University of Zagreb published in 1998"

Comparative analysis of genetic similarity among maize inbred lines detected by RFLPs, RAPDs, SSRs, and AFLPs

Abstract: DNA-based fingerprinting technologies have proven useful in genetic similarity studies. RFLP is still most commonly used in the estimation of genetic diversity in plant species, but the recently developed PCR-based marker techniques, RAPDs, SSRs and AFLPs, are playing an increasingly important role in these investigations. Using a set of 33 maize inbred lines we report on a comparison of techniques to evaluate their informativeness and applicability for the study of genetic diversity. The four assays differed in the amount of polymorphism detected. The information content, measured by the expected heterozygosity and the average number of alleles, was higher for SSRs, while the lowest level of polymorphism was obtained with AFLPs. However, AFLPs were the most efficient marker system because of their capacity to reveal several bands in a single amplification. In fact, the assay efficiency index was more than ten-fold higher for AFLPs compared to the other methods. Except for RAPDs, the genetic similarity trees were highly correlated. SSR and AFLP technologies can replace RFLP marker in genetic similarity studies because of their comparable accuracy in genotyping inbred lines selected by pedigree. Bootstrap analysis revealed that, in the set of lines analysed, the number of markers used was sufficient for a reliable estimation of genetic similarity and for a meaningful comparison of marker technologies.

A Generalization of a Theorem of Baker and Davenport

Abstract: The Greek mathematician Diophantus of Alexandria noted that the rational numbers 1 16 , 33 16 , 17 4 and 105 16 have the following property: the product of any two of them increased by 1 is a square of a rational number (see [4]). The first set of four positive integers with the above property was found by Fermat, and it was {1, 3, 8, 120}. A set of positive integers {a1, a2, . . . , am} is said to have the property of Diophantus if aiaj +1 is a perfect square for all 1 ≤ i < j ≤ m. Such a set is called a Diophantine m-tuple (or P1-set of size m). In 1969, Baker and Davenport [2] proved that if d is a positive integer such that {1, 3, 8, d} is a Diophantine quadruple, then d has to be 120. The same result was proved by Kanagasabapathy and Ponnudurai [9], Sansone [12] and Grinstead [7]. This result implies that the Diophantine triple {1, 3, 8} cannot be extended to a Diophantine quintuple. In the present paper we generalize the result of Baker and Davenport and prove that the Diophantine pair {1, 3} can be extended to infinitely many Diophantine quadruples, but it cannot be extended to a Diophantine quintuple.

Osteogenic protein-1 (bone morphogenetic protein-7) reduces severity of injury after ischemic acute renal failure in rat.

Abstract: We have shown that osteogenic protein-1 (OP-1) (bone morphogenetic protein-7) is responsible for the induction of nephrogenic mesenchyme during embryonic kidney development. Gene knock-out studies showed that OP-1 null mutant mice die of renal failure within the first day of postnatal life. In the present study, we evaluated the effect of recombinant human OP-1 for the treatment of acute renal failure after 60 min bilateral renal artery occlusion in rats. Bioavailability studies in normal rats indicate that approximately 1.4 microg OP-1/ml is available in the circulation 1 min after intravenous administration of 250 microg/kg, which then declines steadily with a half life of 30 min. About 0.5% of the administered OP-1 dose/g tissue is targeted for OP-1 receptors in the kidney. We show that OP-1 preserves kidney function, as determined by reduced blood urea nitrogen and serum creatinine, and increased survival rate when administered 10 min before or 1 or 16 h after ischemia, and then at 24-h intervals up to 72 h after reperfusion. Histochemical and molecular analyses demonstrate that OP-1: (a) minimizes infarction and cell necrosis, and decreases the number of plugged tubules; (b) suppresses inflammation by downregulating the expression of intercellular adhesive molecule, and prevents the accumulation and activity of neutrophils; (c) maintains the expression of the vascular smooth muscle cell phenotype in pericellular capillaries; and (d) reduces programmed cell death during the recovery. Collectively, these data suggest that OP-1 prevents the loss of kidney function associated with ischemic injury and may provide a basis for the treatment of acute renal failure.

Observation of a (Sigma)He-4 bound state in the He-4(K-,pi-) reaction at 600-MeV/c

Abstract: We have observed a clear peak below the {Sigma}{sup +} -production threshold in the {sup 4}He( K{sup {minus}},{pi}{sup {minus}}) reaction at 600 MeV/c and {theta}{sub K{pi}}=4{sup {circ}} . This is confirmation of the existence of the bound state of {sup 4}{sub {Sigma}}He , which was reported in the {sup 4}He(stopped K{sup {minus}},{pi}{sup {minus}}) reaction. As in the case of stopped kaons, no such peak was found in the {sup 4}He(K{sup {minus}} ,{pi}{sup +}) spectrum. Quantitatively reliable parameters for this level have been established. The binding energy and the width of the bound state are 4.4{plus_minus}0.3(stat){plus_minus}1(syst ) MeV and 7.0{plus_minus}0.7(stat){sup +1.2}{sub {minus}0.0}(syst) MeV, respectively. {copyright} {ital 1998} {ital The American Physical Society}

On reducibility of parabolic induction

Abstract: Jacquet modules of a reducible parabolically induced representation of a reductivep-adic group reduce in a way consistent with the transitivity of Jacquet modules. This fact can be used for proving irreducibility of parabolically induced representations. Classical groups are particularly convenient for application of this method, since we have very good information about part of the representation theory of their Levi subgroups (general linear groups are factors of Levi subgroups, and therefore we can apply the Bernstein-Zelevinsky theory). In the paper, we apply this type of approach to the problem of determining reducibility of parabolically induced representations ofp-adic Sp(n) and SO(2n+1). We present also a method for getting Langlands parameters of irreducible subquotients. In general, we describe reducibility of certain generalized principal series (and some other interesting parabolically induced representations) in terms of the reducibility in the cuspidal case. When the cuspidal reducibility is known, we get explicit answers (for example, for representations supported in the minimal parabolic subgroups, the cuspidal reducibility is well-known rank one reducibility).

Evaluation of the precision of dimensional measurements of the mandible on panoramic radiographs

Abstract: The purpose of this study was to evaluate the precision of dimensional measurements of the mandible on orthopantomographic images and thus to evaluate their dimensional reliability. Different distances denoted by metal markers were measured on 25 dry mandibles. The same mandibles were then positioned in an orthopantomographic machine, and radiographic images of them were made. Measurements of the same distances were made on the panoramic images and then compared with the results of the measurements on the dry mandibles. All results were statistically analyzed. The results showed significant difference between the magnification factor listed by the manufacturer and calculated magnification factors, the latter being closer to 1.00. The study also showed that linear measurements made on only one side of the panoramic image of a mandible were very close to the actual dimensions of the dry mandible, whereas measurements that extended across the midline of the mandible were greatly enlarged because of large magnification factors; therefore, such measurements should not be made.

Impact of displacement on the psychological well-being of refugee children

Abstract: The war-related stress had a negative impact on the psychological well-being of all children in Croatia, but displaced and refugee children were especially affected. Although refugee children showed impressive resilience, particular attention should be devoted to children who had traumatic experiences immediately prior to displacement. These children either lived without their parents or with parents who had poor coping abilities while displaced; lived in families that had accumulated several stressful experiences; or were housed in large collective refugee centers. The children that had poorer coping capacities and lacked a supportive family environment displayed high levels of stress-related symptomatology throughout the entire refugee period, being at special risk for the development of further psychological difficulties. The findings reported in this study are the result of a five-year follow-up of the same group of refugee children. Data about children's coping abilities with displacement were obtain...

Spectrochemical Characterization of Benzotriazole on Copper

Abstract: The spectroelectrochemical behavior of Cu in 1 M sodium acetate solution, pH 5.8, alone and in the presence of benzotriazole (BTA) was investigated by cyclic voltammetry, impedance spectroscopy, and Raman spectroscopy. Impedance spectra are characterized by two time constants relating to charge transfer and transport of copper ions through the surface film, the latter being the rate-determining factor. The finite diffusion impedance is analyzed using a diffusion factor (B), which is a function of the diffusion layer thickness (d) and the diffusion coefficient (D f ) or Cu + species. The analysis suggests that changes in the film thickness can be monitored in situ by impedance spectroscopy. The values of D t and concentration of Cu + species (c f ) in the film formed in the presence of 1 M BTA were estimated to be of the order 10 -- 1 4 cm 2 s -1 and 10 -6 mol cm -3 , respectively. The results indicate that the film formed at higher inhibitor concentration and longer immersion time behaves almost like an ideal capacitor. Its thickness (up to 20 nm) and protection against corrosion increase by increasing the BTA concentration and immersion time. The results obtained by Raman spectroscopy confirm the model for the complex Cu(I)BTA in which overlap of Cu sp-hybrid atomic orbitals with the N-hybridized lone-pair atomic orbital occurs.

The effect of the photopolymerization method on the quality of composite resin samples

Abstract: An optimal degree of conversion and minimal polymerization shrinkage are generally antagonistic goals, as increased monomer conversion invariably leads to elevated polymerization shrinkage values. However, both parameters are indispensable for an optimal resin composite restoration. A number of approaches have been used to reduce the stress on the restoration cavity wall interface, such as dentine bonding agents to counteract polymerization shrinkage, stress-absorbing lining materials and low-intensity curing lights to control the flow capacity of the material during polymerization. However, the configuration of the cavity and cohesive fractures of the material and surrounding tooth tissues are still a problem in day-to-day clinical practice. A new photopolymerization light source, pulsed laser, ensures a higher degree of conversion and lower polymerization shrinkage, and differentiates this technique from standard polymerization methods and continuous-wave argon laser polymerization. The coherence and monochromacity of pulsed laser light set at 468 nm and the far greater intensity of laser nanopulses produce a saturation effect in the depths of the composite, thus resulting in higher monomer conversion. The total amount of energy illuminating the sample surface, which is only one-fifth of that of conventional methods, and the cooling and relaxation of the material between nanopulses may be responsible for the reduced net polymerization shrinkage.

Low-Toxicity Copper Corrosion Inhibitors

Abstract: The efficiency of various imidazole derivatives as corrosion inhibitors for copper in hydrochloric and sulfuric acids (HCl and H2SO4) was investigated. Electrochemical measurements showed the organic compounds investigated have fairly good inhibiting properties, except for 4-methyl-5-imidazole-carbaldehyde in HCl. Protecting properties of most imidazole derivatives were close to those of commercial inhibitors for copper. Evaluation of the toxicity of the water solutions on the biological system for treatment of waste water — as measured in regard to chemical oxygen demands (COD), aerobic, and anaerobic toxicity — showed the tested inhibitors have relatively low toxicity.

Fibrinolytic and anticoagulative activities from the earthworm Eisenia foetida

Abstract: Biologically active glycolipoprotein complex (G-90) isolated from whole earthworm tissue extract shows anticoagulative and fibrinolytic activities. We isolated two tyrosine like serine peptidases with molecular masses of 34 kDa (P I) and 23 kDa (P II), respectively. P I peptidase is autocatalytically degraded to P II. Both peptidases exhibit fibrinolytic and anticoagulative activities. The activity of P I is much higher. P I in concentration of 10(5) ng ml-1 of plasma shortened the physiological time of fibrin clot lysis by 54% and completely inhibited blood clotting at a concentration of 10(3) ng ml-1 of venous blood.

Displaced Adolescents in Croatia: Sources of stress and posttraumatic stress reaction

Abstract: This study explored sources of stress and psychosocial reactions of adolescents displaced as a result of the war in the Republic of Croatia. The most frequent stressful events they faced were loss of home (80%), loss of personal belongings (66.7%), separation from family members (66.7%), damage to property (48.9%), exposure to enemy attacks (46.7%), and death of a family member or friend (37.8%). Among the most frequent posttraumatic stress reactions were intrusive images (48.9%), loss of interest (40.9%), restlessness (37.8%), appetite disturbances (33.3%), and increased irritability (31.1%). The exposure to a greater number of stressful events was related to increased depression. More posttraumatic stress reactions were evident in females, in adolescents who were exiled for longer periods, and in those whose parents were more anxious. Adolescents who manifested a higher number of stress reactions had poorer expectations regarding their future.

Septate uterus : Detection and prediction of obstetrical complications by different forms of ultrasonography

Abstract: The aims of the study were to compare the accuracy of transvaginal ultrasonography, transvaginal color Doppler sonography, hysterosonography, and three-dimensional ultrasonography in detection of septate uterus and to evaluate the occurrence of obstetrical complications in relation to septal dimension and vascularity. Each patient underwent transvaginal ultrasonography and color Doppler examination, whereas hysterosonography and three-dimensional ultrasonography were carried out in 76 and 86 patients, respectively. The sensitivity of different sonographic imaging modalities ranges between 95.21% and 99.29%. Color and pulsed Doppler sonographic studies of the septal area revealed vascularity in 71.22%. Patients with vascularized septa had a higher prevalence of obstetrical complications than those with avascularized septa (P < 0.05). Three-dimensional ultrasonography and hysterosonography are highly accurate diagnostic tools for detection of uterine septa. We found no correlation between septal dimension and rate of obstetrical complications, although pregnancy loss was most likely to occur in patients with vascularized septa.

Eyebrow keyhole approach in vascular neurosurgery.

Abstract: The authors review their experience in the surgery of intracranial aneurysms via an eyebrow keyhole approach. The eyebrow keyhole approach presumes a skin incision in the lateral two-thirds of the eyebrow followed by small supraorbital craniotomy (15 x 25 mm). Using this approach and an intraoperative endoscope for better visualisation of the aneurysmal neck, the authors operated on thirty-seven patients with forty intracranial aneurysms. There was no mortality, postoperative recovery was fast, and the cosmetic effect was excellent. Advantages and possibilities of this approach are discussed and results are presented. The authors recommend this approach as a minimal invasive surgery procedure in the treatment of intracranial aneurysms. When performed by experienced vascular neurosurgeons this approach is neither more difficult for the surgeon nor more dangerous for the patient than any other standard craniotomy procedure. According to the authors' present results, surgery of intracranial aneurysm via an eyebrow keyhole approach is the method of choice when performed by an experienced vascular neurosurgeon.

Corrosion protection of aluminium in acidic chloride solutions with nontoxic inhibitors

Abstract: Corrosion kinetics of 99.6% aluminium covered by a thin spontaneously formed oxide film in hydrochloric acid solution with and without the presence of substituted N-aryl pyrroles was studied using electrochemical impedance spectroscopy and quasi steady-state polarization. Measurements were performed on a rotating disc electrode in an argon-deaerated solution in the temperature range 20 to 50°C. The addition of inhibitor considerably increases overvoltage of the cathodic process (HER) and shifts Ecorr to negative potential values. The activation energy of the hydrogen evolution reaction was Ea=50±5kJmol−1 and was not affected by the presence of inhibitor. The inhibitory action occurs by π-bonding between the adsorbed inhibitor molecules and the electrode surface. The electrode coverage follows the Langmuir adsorption isotherm with an adsorption equilibrium constant K=1.1–2.64×105dm3mol−1. The adsorption of organic compound prevents the adsorption of chloride ions and slow down the rate of corrosion.

Toward Organic Superbases: The Electronic Structure and the Absolute Proton Affinity of Quinodiimines and Some Related Compounds

Abstract: Several molecular systems that may well serve as potent organic superbases are examined by using ab initio and semiempirical theoretical models. It is found that the imino group attached to the sem...

Parental history of hypertension and parental history of diabetes and microvascular complications in insulin‐dependent diabetes mellitus: the EURODIAB IDDM complications study

Abstract: Diabetic nephropathy clusters in families, suggesting an inherited predisposition. Parental history of hypertension and of Type 2 diabetes mellitus have been associated with nephropathy in offspring with Type 1 diabetes in some studies but not in others. The associations of parental history of hypertension and of diabetes with both albuminuria and proliferative retinopathy were studied in a large cross-sectional study of 3250 patients with Type 1 diabetes, from 16 European countries. Albuminuria was associated with hypertension in a parent (p < 0.01 in men, p < 0.05 in women), adjusted for age. Patients with a parental history of hypertension had a higher prevalence of hypertension (p < 0.001 in men, p < 0.01 in women) and a higher prevalence of parental diabetes (p < 0.001 in men, p < 0.001 in women). The association of albuminuria with parental hypertension was independent of parental diabetes in men but not women (OR = 1.28 in men p = 0.04, OR = 1.25 in women p = 0.09) and was not independent of hypertension in the patient him/herself in either sex. Albuminuria was associated with parental diabetes in women only (OR = 1.36, p = 0.04). This association was independent of both parental hypertension and hypertension in the patient herself. Proliferative retinopathy was not associated with parental hypertension or diabetes. The implications of these data are that both candidate genes for hypertension and Type 2 diabetes should be considered in the search for the genetic determinants of diabetic nephropathy. © 1998 John Wiley & Sons, Ltd.