Showing papers by "University of Zagreb published in 1988"

Prenatal development of neurons in the human prefrontal cortex. II. A quantitative Golgi study.

Abstract: The quantitative development of neurons in the human dorsolateral and lateral prefrontal cortex was studied in Golgi-impregnated tissue from postmortem brains ranging from 13.5 weeks of gestation up to the second postnatal month. Pyramidal neurons in the future layers III and V of the cortical plate, as well as different types of neurons in the transient subplate zone, were studied. The basal dendrites of the future layer III and V pyramidal neurons show a slow increase during the first two-thirds of the period of gestation. From 27-32 weeks of gestation on, there is a rapid increase in the length of basal dendrites of layer III and V pyramidal neurons, while the number of basal dendrites per pyramidal neuron appears to stabilize at 26/27 weeks of gestation. The increase in total length of basal dendrites per pyramidal neuron is mainly due to an increase in the number of bifurcations and the growth of terminal segments. Throughout the whole period studied, the size of the layer III pyramidal basal dendritic tree was smaller than that of layer V pyramidal neurons. Thus, not until postnatal life do the layer III pyramidal basal dendrites become larger than those of layer V. No statistically significant differences were found for data of the pyramidal neurons between the superior and middle frontal gyri. The dendritic size of subplate neurons, except for the subplate inverted pyramidal neurons, significantly exceeds the size of the basal dendrites of the pyramidal neurons up to the seventh gestational month, which indicates an earlier maturation of these subplate neurons. During the period examined, no clear decrease in the size of the subplate neurons was observed. The present study shows that the dendritic parameters of either subplate or cortical plate pyramidal neurons rapidly increase during the periods of ingrowth of afferent fibers into the subplate zone and cortical plate, respectively. In the Golgi preparations of the prefrontal cortex, the size of the subplate neurons does not show any clearly regressive changes at the end of the prenatal period.

Asymptotic theory and analysis for displacements and stress distribution in nonlinear elastic straight slender rods

Abstract: An asymptotic expansion method is applied to nonlinear three-dimensional elastic straight slender rods. Nonlinear ordinary differential equations for approximate displacements and explicit formulas for approximate stress distributions are obtained. Mathematical properties of these models are studied.

2 pi resonance features in the electronic spectra of chemisorbed CO.

Abstract: The electronic spectra of CO chemisorbed on transition metals and copper as obtained with photoelectron spectroscopies, surface Penning spectroscopy, inverse photoemission spectroscopy, and x-ray absorption spectroscopy are discussed in regard to inherent features pointing to the existence of a CO 2${\ensuremath{\pi}}^{\mathrm{*}}$--derived resonance in these adsorption systems. Since the various spectroscopies probe the CO-metal systems predominantly in the excited final state, the spectra of one and the same line, however, are also affected by differences in the dynamic relaxation processes and nonequilibrium final-state charge configurations which are specific to each particular experimental method. In order to arrive at a unified interpretation of some seemingly controversial features in the electronic spectra of chemisorbed CO, we have invoked the notion of the CO 2${\ensuremath{\pi}}^{\mathrm{*}}$--derived resonance. Our model includes both initial-state chemical (i.e., backdonation-induced bonding) effects and final-state dynamical screening (relaxation) effects. Assuming a very small fractional occupation of the CO 2${\ensuremath{\pi}}^{\mathrm{*}}$ resonance in the case of weak chemisorption systems (e.g., CO/Cu), and notably larger occupation in the case of strong chemisorption (e.g., CO/Ni), it is possible to give a unified interpretation of the experimental features such as the threshold energies, level shifts, line shapes, etc., observed with CO adsorbed on transition metals and copper. The great success of the concept of a resonance in interpreting these experimental spectral features as obtained with the various spectro- scopies, provides, in turn, strong support for the actual existence of a CO 2${\ensuremath{\pi}}^{\mathrm{*}}$-- derived resonance in these adsorption systems.

Size of Josephson junctions in Ba-Y-Cu-O compounds

Abstract: Microwave-absorption measurements using a conventional electron-spin resonance spectrometer provide a novel leadless technique for the detection of Josephson junctions and their size in superconductive Ba-Y-Cu-O compounds.

Respiratory findings in spice factory workers.

Abstract: The respiratory consequences of working in the spice industry were studied in 92 female spice factory workers (mean age, 36 yr; mean exposure, 12 yr). A control group of 104 female workers employed in a nondusty industry was also studied. The prevalence of chronic respiratory symptoms was significantly higher in the exposed than in the control group. In particular, the prevalence of dyspnea (57.6%), chronic cough (22.8%), chronic phlegm and chronic bronchitis (19.6%), nasal catarrh (37.0%), and sinusitis (22.2%) was high when compared to controls (p less than .01). Among spice factory workers, a high prevalence of acute symptoms during the workshift was recorded. Acute reductions in lung function were statistically significant over the workshift for forced vital capacity (FVC), -2.0%; forced expiratory volume in one second (FEV1.0), -3.0%; and for maximum expiratory flow rates at 50% (FEF50), -8.3% and at 25% (FEF25), -15.2% measured on maximum expiratory flow-volume (MEFV) curves. No difference was found in across-shift ventilatory function in workers with or without chronic respiratory symptoms, except for FEF25 (with symptoms, 16.7%; without symptoms, 9.6%). Preshift administration of 40 mg of disodium cromoglycate (DSC) inhaled 15 min before the workshift significantly diminished acute reductions in FEF50 and FEF25 in exposed workers. Monday preshift FEF50 and FEF25 in exposed workers were significantly lower than in control workers (p less than .01), which suggests an early irreversible component to this illness.

Neural and massively parallel computers: the sixth generation

Abstract: FUTURE TRENDS: SIXTH GENERATION. Advances in Logic and Knowledge Engineering. Systems Emulating Human Behavior. Systems Emulating Brain-Behavior Functions. BRAIN-LIKE SYSTEMS UNDER DEVELOPMENT. Cognitrons and Neocognitrons. Adaptive Learning Systems. Goal-Directed Systems. Digital Transformation Systems and Pseudo-Associative Memories. Associative-Memory Based Systems. Massively Parallel Systems. BIOMODELS AND HARDWARE ARCHITECTURES. Simulation of Biological Systems. Biosignals and their Computer Processing. Communication Based on Timing in Insects. Communication Based on Frequency Pattern Recognition in Birds. Models of Quantized Information Transmission on Neural Terminals. BIOLANGUAGES AND SOFTWARE. Information Coding. Communication Based on Pulse Pattern Recognition of Fireflies. Brain Window Logic. Brain Window Language.

Comparative efficacy of triclabendazole, nitroxynil and rafoxanide against immature and mature Fasciola hepatica in naturally infected cattle.

Abstract: In two trials the fasciolicidal activities of triclabendazole, nitroxynil and rafoxanide were assessed in cattle naturally infected with predominantly immature stages of Fasciola hepatica. Tablets containing 900 mg triclabendazole were administered orally at a dose rate of 12 mg/kg bodyweight. Rafoxanide and nitroxynil were used at a dose rate of 10 mg/kg, rafoxanide being given orally and nitroxynil by subcutaneous injection. Based on faecal egg counts nine weeks after treatment the efficacies were calculated to be 100 per cent for triclabendazole and 95.0 per cent for nitroxynil in the first trial and 98.4 per cent for triclabendazole and 52.9 per cent for rafoxanide 15 weeks after treatment in the second trial. In the first trial five animals from each of the three groups were slaughtered and their fluke burdens counted. Compared with the untreated control group the reductions in the fluke burdens were 96.9 per cent in triclabendazole treated cattle and 76.4 per cent in the nitroxynil treated group.

The cytologic identification and quantification of testicular cell subtypes. Reproducibility and relation to histologic findings in the diagnosis of male infertility.

Abstract: In testicular imprint smears from 100 infertile men (both testicles), stained using the Pappenheim and Papanicolaou methods, the cell forms (light and dark spermatogonia, primary and secondary spermatocytes, spermatids, spermatozoa and Sertoli cells) were identified and quantified by the counting of 500 consecutive cells. Identification of the cell types, which are described and illustrated, was consistent and reproducible; the advantages of the different stainings in their analysis is documented. The cell counts were tested for reproducibility and compared to the histologic diagnoses and sperm counts. Statistical analysis showed the highest reproducibility for cells frequently encountered in smears (0.99 for Sertoli cells and 0.98 for spermatozoa) and the lowest but still satisfactory reproducibility for rare or arbitrarily defined cell forms (0.71 for dark spermatogonia and 0.76 for secondary spermatocytes). The high reproducibility of the smear quantification permits the introduction of a number of indices, defining clinically useful relations between cell types that are indicative of various types of infertility. The data obtained by cytologic quantification showed reasonably good correlation with the histologic diagnoses of desquamation and focal fibrosis and excellent correlation with Sertoli cells only, arrested spermatogenesis and complete fibrosis. The cytologic quantification of testicular smears adds considerable information to the diagnosis of impaired fertility and should be instituted in properly equipped centers.

Pressure-induced metal-to-insulator phase transitions in the organic conductor (2,5 DM-DCNQI)2Cu

Abstract: The electrical resistivity along the high-conductivity axis has been measured at pressures up to 9 kbar in the novel organic conductor (2,5 DM-DCNQI)2Cu. Deviations from the usual linear behaviour of the conductivity under pressure at room temperature have been observed. Moreover, at lower temperatures metal-to-insulator phase transitions have been induced with values of transition temperatures depending on the applied pressure. The obtained results are discussed and compared with corresponding data for other organic compounds. A tentative interpretation of this novel and unusual phase diagram is proposed in terms of a mixed valence state for copper ions.

Protection of mouse bone marrow by WR-2721 after fractionated irradiation.

Abstract: The ability of WR-2721 to protect mouse bone marrow after single or fractionated doses of radiation was assessed using both a clonogenic assay (survival of colony-forming units spleen (CFU)) and a functional assay (lethality at 30 days) of stem cell survival. Cell survival curves and dose-response curves for radiation alone and drug with radiation were constructed over the dose range of .5 to 8 Gy and 1.5 to 15 Gy, respectively. The fractionated regimen consisted of four fractions ranging from 0.5 to 1.75 Gy given at 6-hr intervals for a total treatment time of 19.5 hr. WR-2721 was given 30 min before each fraction at a dose of 200 mg/kg. The protection factor was smaller after fractionated doses than after single doses for both assays, 1.3 (95% c.l., 1.0–1.6) vs. 2.3 (95% c.l., 2.0–2.6) for CFU survival and 1.34 vs. 1.8 for lethality at 30 days. No drug cytotoxicity could be demonstrated in the fractionated schedule. These data suggest that protection by WR-2721 is dependent on size of dose and will be less after clinically relevant, small dose fractions. However, some protection does remain even in the low dose range, where proportionally more damage is due to single-hit irreparable events.

Adriatic Sea and Land Breezes: Clockwise Versus Anticlockwise Rotation

Abstract: Rotary spectra were computed from wind data collected in the summers of 1978 and 1979 at six stations along the east Adriatic coast. The spectra showed diurnal peaks associated with sea and land breezes and their spatial variability is analyzed in this note. It appears that the energy of sea and land breezes diminishes with latitude. Moreover, the breezes generally turn clockwise, with the exception of the Senj station where a slight predominance of anticlockwise rotation occurs. It is suggested that the Senj breezes are modified by topographically induced flows.

Cytoplasmic steroid receptors in cancer of the larynx.

Abstract: There are many data that suggest that the larynx is a target organ for steroid hormones, especially androgens. Since laryngeal cancers occur much more often in males, it is conceivable that androgens might be the growth-stimulating factor for such tumors. In order to test this concept further, neoplastic tissues from 68 patients (64 males, 4 females) were obtained during planned total laryngectomies and were tested for the presence of androgen (AR) and estrogen (ER) receptors. In 18 cases progesterone receptors (PgR) were also quantified. The dextrancoated charcoal technique was used to determine hormone receptors and the number of the binding sites and the equilibrium constant of dissociation were calculated according to Scatchard. 3H-R1881 was used as the ligand for the measurement of AR, 3H-estradiol for ER, and 3H-R5020 for PgR. AR was present in 11 tumor specimens (1 female, 10 males) and the concentration varied from 2.8 to 17.1fmol/ mg proteins. ER were found in 6 tumors (1 female, 5 males) in concentrations of 2.9–11.2 fmol/mg proteins. Three tumor specimens contained both AR and ER. All tumors analyzed lacked PgR. These results suggest that at least some laryngeal carcinomas might be hormone dependent, indicating that certain patients could benefit from antiandrogen therapy.

Short-term and long-term stimulation of Na+−H+ exchange in cortical brush-border membranes during compensatory growth of the rat kidney

Abstract: The effect of unilateral nephrectomy on Na+−H+ exchange in rat renal cortical brush-border membrane vesicles (BBMV) was studied by the method of acridine orange fluorescence quenching. The exchanger activity in BBMV from remnant kidney increased rapidly by 70–75% within first 30 min following uninephrectomy. Only a slight further increase was found in later stages of renal growth, i.e. 30 min to 7 days following uninephrectomy. The changes in antiporter activity were restricted toV max, whereas theK m for Na+ was similar in control and compensatory growing kidney. The increase of Na+−H+ exchange at 15 min was not affected by actinomycin D in vivo, whereas the increase at 48 h was completely abolished indicating that protein synthesis could be involved in the late, but not in the initial stimulation of renal Na+−H+ exchange. The late, but not the initial stimulations of Na+−H+ exchange were associated with elevated activities of cortical (Na++K+)-ATPase indicating that changes in antiporter activity precede those in the (Na++K+)-pump. The early stimulation of Na+−H+ exchange in BBMV in one kidney was induced also by the occlusion of blood flow through the contralateral kidney for 15 min, without removing it. Thirty min after the occlusion was removed and the reflow established, the Na+−H+ exchange in BBMV from the intact kidney decreased to the control values. The observed modulations in renal Na+−H+ exchanger may be regulated by phosphorylation-dephosphorylation events. In support, the concentration of a well known protein kinase C activator, 1,2-diacylglycerol, in the cortical tissue of the remnant kidney increased up to 100% within 5 min following unilateral nephrectomy and preceded the increase in Na+−H+ exchange. The early stimulation of Na+−H+ exchange may be a “trigger” in initiating the kidney growth.

Respiratory symptoms and ventilatory capacity in soy bean workers.

Abstract: Respiratory function was studied in a group of 29 soy workers exposed to soy bean dust produced after extraction of soy oil. The prevalence of all chronic respiratory symptoms was consistently higher in exposed than in control workers, although the differences were not statistically significant. During the Monday work shift there was a significant mean acute across-shift decrease in maximum expiratory flow rates at 50% and 25% vital capacity (FEF50: -6.4%; FEF25: -12.4%). Changes in vital capacity (FVC: -3.6%) and 1-sec forced expiratory volume (FEV1: -2.7%) were smaller, but still statistically significant. There were also statistically significant acute reductions in all ventilatory capacity parameters over the work shift on the following Friday, although the changes were in general smaller than on Monday (except for FEV1). An analysis of Monday preshift values of ventilatory capacity in soy bean workers suggests that exposure to soy bean dust may lead to chronic respiratory impairment in some workers.