Showing papers by "Bar-Ilan University published in 1992"
TL;DR: Photosensitization of Escherichia coli and Pseudomonas aeruginosa cells by deuteroporphyrin (DP) is shown to be possible in the presence of the polycationic agent polymyxin nonapeptide (PMNP).
Abstract: Photosensitization of Escherichia coli and Pseudomonas aeruginosa cells by deuteroporphyrin (DP) is shown to be possible in the presence of the polycationic agent polymyxin nonapeptide (PMNP) Previous studies established complete resistance of Gram-negative bacteria to the photodynamic effects of porphyrins The present results show that combined treatment of E coli or P aeruginosa cultures with DP and PMNP inhibit cell growth and viability No antibacterial activity of PMNP alone could be demonstrated and cell viability remained unchanged Spectroscopically, PMNP was found to bind DP, a mechanism which probably assists its penetration into the cell's membranes Insertion of DP into the cells was monitored by the characteristic fluorescence band of bound DP at 622 nm Binding times were 5-40 min and the extent of binding increased with decreasing the pH from 85 to 65 DP binding constants, as well as the concentrations of PMNP which were required for maximal effect on the various Gram-negative bacteria, were determined fluorometrically By the treatment of DP, PMNP and light the growth of E coli and P aeruginosa cultures was stopped and the viability of the culture was dramatically reduced Within 60 min of treatment the survival fraction of E coli culture was 9 x 10(-6) and that of P aeruginosa was 52 x 10(-4) Electron microscopy depicted ultrastructural alterations in the Gram-negative cells treated by DP and PMNP The completion of cell division was inhibited and the chromosomal domain was altered markedly
339 citations
TL;DR: In this paper, the Li cycling efficiency surface chemistry and Li morphology in ethylene carbonate (EC) and propylene carbonates (PC) based electrolyte solutions were investigated and correlated surface sensitive ex situ FTIR spectroscopy, X-ray microanalysis and scanning electron microscopy were used in conjunction with standard electrochemical techniques.
314 citations
312 citations
TL;DR: In this paper, the authors examined the relation between feelings of job insecurity and various attitudes and opinions of employees towards their work and the organization and showed that JI is associated with more negative evaluations of all aspects of the company and the job, including more objective variables such as the quality of products and services.
Abstract: Examines the relations between feelings of job insecurity (JI) and various attitudes and opinions of employees towards their work and the organization. Analyses survey data from 11 European high‐tech organizations with a total of 8,483 respondents. Shows that JI is associated with more negative evaluations of all aspects of the company and the job, including more objective variables such as the quality of products and services. Particularly high correlations are observed between JI and negative judgements on management and the company in general. Further presents the development of a questionnaire to assess JI. The questionnaire is then used to study differential effects of JI on persons with internal and external locus of control, and with high and low social support.
266 citations
TL;DR: It is suggested that low-level laser therapy in the visible and in the near-infrared region is due to cell respiration stimulation by either the endogenous porphyrins in the cell, or by the cytochromes.
Abstract: The effect of 360, 632 and 780 nm light on NIH fibroblast cells was examined. Mitosis counts of irradiated cells at various energy doses were taken. Scanning electron micrographs of these cells were studied. It is suggested that low-level laser therapy in the visible and in the near-infrared region is due to cell respiration stimulation by either the endogenous porphyrins in the cell, or by the cytochromes.
233 citations
TL;DR: In this paper, charred plant remains, 19,000 years old, were uncovered at Ohalo II on the shore of the Sea of Galilee, Israel, and provided insights into the subsistence strategy of the earliest known hunter-gatherer community of the Levantine Epipaleolithic period.
218 citations
TL;DR: In this paper, a review of surface-specific X-ray diffraction and fluorescence techniques for Langmuir monolayers at the air-liquid interface can be found.
Abstract: The advent of well-collimated, high-intensity synchrotron X-ray sources and the consequent development of surface-specific X-ray diffraction and fluorescence techniques have recently revolutionized the study of Langmuir monolayers at the air–liquid interface. These methods allowed for the first time the determination of the in-plane and vertical structure of such monolayers with a resolution approaching the atomic level. We briefly describe these methods, including grazing incidence X-ray diffraction, specular reflectivity, Bragg rods, standing waves, and surface fluorescence techniques, and review recent results obtained from them for Langmuir films. The methods have been successfully applied in the elucidation of the structure of crystalline aggregates of amphiphilic molecules such as alcohols, carboxylic acids and their salts, α-amino acids, and phospholipids at the water surface. In addition, it became possible to monitor by diffraction the growth and dissolution of the crystalline self-aggregates as well as structural changes occurring by phase transitions. Furthermore, the surface X-ray methods shed new light on the structure of the underlying ionic layer of attached solvent or solute species. Examples are given where singly or doubly charged ions bound to the two-dimensional (2D) crystal form either an ordered or diffuse counterionic layer. Finally, the surface diffraction methods provide data on transfer of structural information from 2D clusters to 3D single crystals, which had been successfully accomplished by epitaxial-like crystallization both in organic and inorganic crystals.
169 citations
TL;DR: Using a sample of 809 female soldiers in their late teens, results showed that the EAT-26 is reliable, the factor structure is different from that obtained in clinical groups, and the E AT- 26 is significantly correlated with body image, weight, and diet.
Abstract: One of the more frequently used measures of eating disorders is the 40-item Eating Attitudes Test (EAT) developed by Garner and Garfinkel (1979). Although originally designed to diagnose anorexia nervosa, the test has recently been applied to nonclinical populations also. In this study, we examined psychometric and validity data for a short version of the scale, the EAT-26. Using a sample of 809 female soldiers in their late teens, results showed that the EAT-26 is reliable, the factor structure is different from that obtained in clinical groups, and the EAT-26 is significantly correlated with body image, weight, and diet.
166 citations
TL;DR: The correlations were found to be highest for TSD of greater than or equal to 45 h, speed rather than accuracy measures of performance, and work-paced rather than self-paced tasks, consistent with the "lapse hypothesis" that posits microsleeps during long hours of sleep deprivation.
Abstract: Studies consistently show that total sleep deprivation (TSD) and measures of performance are negatively correlated. However, an accurate quantitative summary of the relationship between these variables has not yet been reported. After collection of the data from 27 relevant studies, meta-analytic techniques were used to test several hypotheses. The correlations were found to be highest for TSD of greater than or equal to 45 h, speed rather than accuracy measures of performance, and work-paced rather than self-paced tasks. These findings are consistent with the "lapse hypothesis" that posits microsleeps during long hours of sleep deprivation.
152 citations
TL;DR: In this paper, the impact of promotion decisions on equity, commitment, and behavioral outcomes was examined in a field setting, where workers in a service comapny who submitted their candidacy for promotion to either department or division heads were compared with their noncandidate counterparts.
Abstract: The impact of promotion decisions on equity, commitment, and behavioral outcomes was examined in a field setting. Workers in a service comapny who submitted their candidacy for promotion to either department or division heads were compared with their noncandidate counterparts (total N=191). Subjects completed surveys after promotion decisions were made. In addition, measures of the subjects' lateness and absence before and after the promotion were available. Data analyzed by level of position (departement vs. division) and promotion decision (promoted, not promoted, and control) indicated that promotions resulting from self-initiated condidacies might actually produce undiserable outcomes. Failure to get a promotion as associated with feelings of inequity, a decrease in commitment, and an increase in absenteeism, positive promotion decisions increased commitment. Theoretical and organizational implications are discussed
140 citations
TL;DR: An algorithm for generating long-range correlations in the percolation problem is developed and it is found that the fractal dimensions of the backbone and the red bonds are quite different from uncorrelatedPercolation and vary with \ensuremath{\lambda}, the strength of the correlation.
Abstract: We develop an algorithm for generating long-range correlations in the percolation problem and investigate their effect on both structural and dynamical properties of the incipient infinite cluster in two dimensions. We find that the fractal dimensions of the backbone and the red bonds (singly connected bonds) are quite different from uncorrelated percolation and vary with \ensuremath{\lambda}, the strength of the correlation. Also, we find that the conductivity exponent varies with \ensuremath{\lambda}.
TL;DR: The higher porphyrin cellular content under EDTA and 5-ALA induction was exploited to photoinactivate the human leukemic cells by more then 3 orders of magnitude.
TL;DR: In vivo and in vitro results suggest that (pivaloyloxy)methyl butyrate (1a) is a potential antineoplastic agent.
Abstract: The antitumor activity of novel prodrugs butyric acid was examined. The in vitro effect of the compounds on induction of cytodifferentiation and on inhibition of proliferation and clonogenicity showed that (pivaloyloxy)methyl butyrate (1a) (labeled AN-9) was the most active agent. SAR's suggested that its activity stemmed from hydrolytically released butyric acid. In vivo, 1a displayed antitumor activity in B16F0 melanoma primary cancer model, manifested by a significant increase in the life span of the treated animals. Murine lung tumor burden, induced by injection of the highly metastatic melanoma cells (B16F10.9), was decreased by 1a. It also displayed a significant therapeutic activity against spontaneous metastases which were induced by 3LL Lewis lung carcinoma cells. Moreover, 1a has the advantage of low toxicity, with an acute LD50 = 1.36 +/- 0.1 g/kg (n = 5). These results suggest that 1a is a potential antineoplastic agent.
TL;DR: The D-galactose-binding lectin (PA-I) from the bacterium Pseudomonas aeruginosa, isolated by affinity chromatography on Sepharose, was examined for its relative affinities for simple sugars and their derivatives using equilibrium dialysis and hemagglutination inhibition tests.
TL;DR: In this article, a technique different from the boundary layer method is developed to deal with singularly perturbed optimal control problems, which is applicable in particular in the case when the optima...
Abstract: A technique different from the boundary layer method is developed to deal with singularly perturbed optimal control problems. The technique is applicable, in particular, in the case when the optima...
TL;DR: It is proposed that PKC is involved in the mammalian sperm acrosome reaction by means of addition of phorbol 12-myristate-13-acetate or the membrane-permeant diacylglycerol analogue 1-oleoyl-2-acetyl glycerol to bovine spermatozoa.
Abstract: Mammalian spermatozoa undergo a Ca(2+)-dependent exocytotic event before fertilization which is known as the acrosome reaction. The process of exocytosis in several cell systems is mediated by a protein kinase C (PKC)-catalysed phosphorylation. Addition of phorbol 12-myristate-13-acetate or the membrane-permeant diacylglycerol analogue 1-oleoyl-2-acetylglycerol, which are potent activators of PKC, to bovine spermatozoa resulted in stimulation of the acrosome reaction. This stimulation was inhibited by low concentrations (50% inhibition at 0.7 nM) of the PKC inhibitor staurosporine. PKC specific activity in bovine spermatozoa is extremely low in comparison with other cells; however, it is comparable with the activity found in human spermatozoa. Immunohistochemical analysis using anti-PKC antibodies revealed staining in the equatorial segment, the post-acrosomal region and the upper region of the head. We propose that PKC is involved in the mammalian sperm acrosome reaction.
TL;DR: Cellular immune suppression was examined in patients with end-stage renal disease following a single blood transfusion, finding that the proliferating OKT8+ cells are in large part a subset of suppressor cells.
TL;DR: There is an acceleratedCa2+ transport in the irradiated cells, which means that laser light can stimulate Ca2+ exchange through the cell membrane, which may cause transient changes in the cytoplasmic Ca2+, which, in spermatozoa, has a regulatory role in control of motility and acrosome reaction, and in other cells can trigger mitosis.
Abstract: The effect of light on calcium transport was studied. Bull sperm cells were irradiated with an HeNe (630 mm) laser and a 780 nm diode laser at various energy doses, and 45Ca2+ uptake was measured by the filtration technique. It was found that there is an accelerated Ca2+ transport in the irradiated cells, which means that laser light can stimulate Ca2+ exchange through the cell membrane. This may cause transient changes in the cytoplasmic Ca2+ concentration which, in spermatozoa, has a regulatory role in control of motility and acrosome reaction, and in other cells can trigger mitosis.
01 Jan 1992
TL;DR: A compact set K ⊂ ℝ n is said to have the Pompeiu property (PP) if the only function is MathType!MTEF!2!1!+- % feaagaart1ev2aaatCvAUfKttLearuavP1wzZbItLDhis9wBH5garm % Wu51MyVXgaruWqVvNCPvMCaebbfv3ySLgzGueE0jxyaibaieYlf9ir % Veeu0
Abstract: A compact set K ⊂ ℝ n is said to have the Pompeiu property (PP) if the only function \( % MathType!MTEF!2!1!+- % feaagaart1ev2aaatCvAUfKttLearuavP1wzZbItLDhis9wBH5garm % Wu51MyVXgaruWqVvNCPvMCaebbfv3ySLgzGueE0jxyaibaieYlf9ir % Veeu0dXdh9vqqj-hEeeu0xXdbba9frFj0-OqFfea0dXdd9vqaq-Jfr % VkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr0-vqpWqaaeaabiGa % ciaacaqabeaadaqaaqaaaOqaaiabdAgaMbaa!3272! f \)∊C(ℝ n ) satisfying for all rigid motions σ of ℝ n is\( % MathType!MTEF!2!1!+- % feaagaart1ev2aaatCvAUfKttLearuavP1wzZbItLDhis9wBH5garm % Wu51MyVXgaruWqVvNCPvMCaebbfv3ySLgzGueE0jxyaibaieYlf9ir % Veeu0dXdh9vqqj-hEeeu0xXdbba9frFj0-OqFfea0dXdd9vqaq-Jfr % VkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr0-vqpWqaaeaabiGa % ciaacaqabeaadaqaaqaaaOqaaiabdAgaMbaa!3272! f \) ≡ 0. A collection K, of compact sets in ℝ n has (PP) if whenever \( % MathType!MTEF!2!1!+- % feaagaart1ev2aaatCvAUfKttLearuavP1wzZbItLDhis9wBH5garm % Wu51MyVXgaruWqVvNCPvMCaebbfv3ySLgzGueE0jxyaibaieYlf9ir % Veeu0dXdh9vqqj-hEeeu0xXdbba9frFj0-OqFfea0dXdd9vqaq-Jfr % VkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr0-vqpWqaaeaabiGa % ciaacaqabeaadaqaaqaaaOqaaiabdAgaMbaa!3272! f \) ∊ C(ℝ n ) and (1) holds for all K ∊ K (and all rigid motions σ) it follows that \( % MathType!MTEF!2!1!+- % feaagaart1ev2aaatCvAUfKttLearuavP1wzZbItLDhis9wBH5garm % Wu51MyVXgaruWqVvNCPvMCaebbfv3ySLgzGueE0jxyaibaieYlf9ir % Veeu0dXdh9vqqj-hEeeu0xXdbba9frFj0-OqFfea0dXdd9vqaq-Jfr % VkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr0-vqpWqaaeaabiGa % ciaacaqabeaadaqaaqaaaOqaaiabdAgaMbaa!3272! f \) ≡ 0.
TL;DR: An extension of an index of segregation recently proposed by Karmel and Maclachlan (1988) is suggested which allows the analysis of occupational segregation in the multidimensional case.
Abstract: An extension of an index of segregation recently proposed by Karmel and Maclachlan (1988) is suggested which allows the analysis of occupational segregation in the multidimensional case.
TL;DR: The empirical results which have been reported support the hypotheses' implied by the model of rational political behavior set out in Section 2. as mentioned in this paper In pre-election periods, local government development expenditures deviate significantly from their normal levels.
Abstract: The empirical results which have been reported support the hypotheses' implied by the model of rational political behavior set out in Section 2. In pre-election periods, local government development expenditures deviate significantly from their normal levels. The extent of deviation is approximately 20%.
TL;DR: In this paper, the effects of simulated light fire on the availability of N and P, and on concentrations of ions in solutions of two typical Mediterranean soils (Chromic Luvisol and Lithic Xerothent) that support an oak shrubland and an Aleppo pine forest respectively were investigated.
TL;DR: In this paper, the correlation between Li-cycling efficiency and Li-surface chemistry in these systems was investigated using surface sensitive Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray microanalysis techniques.
TL;DR: Developmental change in the impact of stressful life events and coping styles were assessed among Israeli preadolescent and adolescent boys, finding that cognitively and practically oriented coping served as effective foils to the adverse effects of stress, whereas emotionally oriented coping was counterproductive.
Abstract: Developmental change in the impact of stressful life events and coping styles were assessed among Israeli preadolescent and adolescent boys. A school sample completed a questionnaire tapping emotionally, cognitively, and practically oriented styles of coping, along with a life event survey. Teachers reported on behavior and adjustment. Analyses revealed that coping among preadolescent males was relatively undifferentiated and of limited efficacy. The transition to adolescence saw an increased qualitative differentiation of emotionally from practically or cognitively oriented coping styles, as well as quantitatively greater use of cognitively oriented coping. Further, cognitively and practically oriented coping served as effective foils to the adverse effects of stress, whereas emotionally oriented coping was counterproductive. Discussion focused on the possible contribution of cognitive growth to coping, as well as the relative utility of adult models for the study of coping in young populations.
TL;DR: Endolithic algae living inside skeletons of living corals are exposed to very low light intensities, and photosynthetic adaptations to low light level and low metabolic activity rates enable the algae to grow in this unique habitat.
TL;DR: The rate of conformational state fluctuations (interconversion between states) was found to be slow on the nanosecond time scale, as expected for a protein with a relatively large interdomain contact area.
Abstract: 3-Phosphoglycerate kinase is composed of two globular domains separated by a wide cleft. The substrate binding sites are situated on the inner surfaces of the two domains. By analogy to other kinases, it has been postulated that the catalytic mechanism of phosphoglycerate kinase involves a hinge bending domain motion that brings the substrates together to allow phosphoryl transfer. To characterize this large-scale conformational change, as well as the dynamics of the unliganded enzyme in solution, we have applied site-directed mutagenesis and time-resolved nonradiative energy transfer techniques. Two genetically engineered cysteines (Cys-135 and Cys-290), one in each of the two domains, were covalently labeled with a donor and acceptor pair of fluorescent probes. Analysis of subnanosecond fluorescence decay curves yielded the equilibrium distribution of interdomain distances. In the absence of substrates, the distribution of distances between the two labeled sites was very broad, with a full width at half maximum estimated as 20 A or broader, indicative of a large number of conformational substates in solution. The mean distance, 31.5 +/- 1 A, was 8 A smaller than in the crystal structure. Upon addition of ATP alone or of ATP and 3-phosphoglycerate, the average distance increased to 38 +/- 1 A and the width of the distribution decreased. Addition of 3-phosphoglycerate alone induced a similar but smaller change. The rate of conformational state fluctuations (interconversion between states) was found to be slow on the nanosecond time scale, as expected for a protein with a relatively large interdomain contact area.
TL;DR: In this paper, the authors reported the first measurements of the mobility/friction coefficients of a sphere dragged horizontally through a vertically vibrated granular medium and argued that the observed mobility is proportional to the fraction of the time spent in the fluid state and discussed the origin of the observed dependence on the various parameters.
Abstract: We report the results of the first measurements of the mobility/friction coefficients of a sphere dragged horizontally through a vertically vibrated granular medium. The friction coefficient depends on the state of excitation of the medium and drops rapidly when the acceleration of the vibrated cell exceeds that of gravity. We propose a simple model involving fluidization/solidification events during a period of vibration of the cell. We argue that the observed mobility is proportional to the fraction of the time spent in the fluid state and discuss the origin of the observed dependence on the various parameters.
TL;DR: Oral administration of AS101 at a dose ranging between 50 and 100 micrograms/mouse promotes hemopoietic regeneration after treatment with sublethal doses of cyclophosphamide and protects mice from the lethal effects of this compound.
TL;DR: The reef/terrace age groups correspond to the oceanic oxygen isotope stages 9, 7, 5e and 1.5-2.5 in the last 300,000 years.
TL;DR: P perturbation analysis results predict a rich behavior for the kinetics of the reaction front in the short-time limit, with variety of universality classes, and it is shown that the center of the front can change its direction of motion.
Abstract: A dynamic reaction zone is produced in the A+B\ensuremath{\rightarrow}C reaction-diffusion system with initially separated components. Our perturbation analysis results predict a rich behavior for the kinetics of the reaction front in the short-time limit, with variety of universality classes. In particular, we show that the center of the front can change its direction of motion. Our experimental data support this prediction and demonstrate that this behavior is measurable over a time scale of hours in bimolecular reactions at room temperature.