Production and characterization of rhamnolipids from Pseudomonas aeruginosa san ai

Production and characterization of rhamnolipid biosurfactant obtained by strain Pseudomonas aeruginosa san ai was investigated. With regard to carbon and nitrogen source several media were tested to enhance production of rhamnolipids. Phosphate-limited proteose peptone-ammonium salt (PPAS) medium supplemented with sun flower oil as a source of carbon and mineral ammonium chloride and peptone as a nitrogen source greatly improved rhamnolipid production, from 0.15 on basic PPAS (C/N ratio 4.0), to 3 g L-1, on optimized PPAS medium (C/N ratio 7.7). Response surface methodology analysis was used for testing effect of three factors: temperature, concentration of carbon and nitrogen source (w/w), in optimized PPAS medium on rhamnolipid production. Isolated rhamnolipids were characterized by IR and ESI-MS. IR spectra confirmed that isolated compound corresponds to rhamnolipid structure, whereas MS indicated that isolated preparation is a mixture of mono-rhamno-mono-lipidic, mono-rhamno-di-lipidic- and dirhamno- di-lipidic congeners

Global Optimization by Energy Landscape Paving

We introduce a novel heuristic global optimization method, energy landscape paving (ELP), which combines core ideas from energy surface deformation and tabu search. In appropriate limits, ELP reduces to existing techniques. The approach is very general and flexible and is illustrated here on two protein folding problems. For these examples, the technique gives faster convergence to the global minimum than previous approaches.Comment: to appear in Phys. Rev. Lett. (2002

Global Optimization by Basin-Hopping and the Lowest Energy Structures of Lennard-Jones Clusters Containing up to 110 Atoms

We describe a global optimization technique using `basin-hopping' in which the potential energy surface is transformed into a collection of interpenetrating staircases. This method has been designed to exploit the features which recent work suggests must be present in an energy landscape for efficient relaxation to the global minimum. The transformation associates any point in configuration space with the local minimum obtained by a geometry optimization started from that point, effectively removing transition state regions from the problem. However, unlike other methods based upon hypersurface deformation, this transformation does not change the global minimum. The lowest known structures are located for all Lennard-Jones clusters up to 110 atoms, including a number that have never been found before in unbiased searches.Comment: 8 pages, 3 figures, revte

Special Functions Related to Dedekind Type DC-Sums and their Applications

In this paper we construct trigonometric functions of the sum T_{p}(h,k), which is called Dedekind type DC-(Dahee and Changhee) sums. We establish analytic properties of this sum. We find trigonometric representations of this sum. We prove reciprocity theorem of this sums. Furthermore, we obtain relations between the Clausen functions, Polylogarithm function, Hurwitz zeta function, generalized Lambert series (G-series), Hardy-Berndt sums and the sum T_{p}(h,k). We also give some applications related to these sums and functions

Strategies for structuring interdisciplinary education in Systems Biology: an European perspective

Systems Biology is an approach to biology and medicine that has the potential to lead to a better understanding of how biological properties emerge from the interaction of genes, proteins, molecules, cells and organisms. The approach aims at elucidating how these interactions govern biological function by employing experimental data, mathematical models and computational simulations. As Systems Biology is inherently multidisciplinary, education within this field meets numerous hurdles including departmental barriers, availability of all required expertise locally, appropriate teaching material and example curricula. As university education at the Bachelor’s level is traditionally built upon disciplinary degrees, we believe that the most effective way to implement education in Systems Biology would be at the Master’s level, as it offers a more flexible framework. Our team of experts and active performers of Systems Biology education suggest here (i) a definition of the skills that students should acquire within a Master’s programme in Systems Biology, (ii) a possible basic educational curriculum with flexibility to adjust to different application areas and local research strengths, (iii) a description of possible career paths for students who undergo such an education, (iv) conditions that should improve the recruitment of students to such programmes and (v) mechanisms for collaboration and excellence spreading among education professionals. With the growing interest of industry in applying Systems Biology approaches in their fields, a concerted action between academia and industry is needed to build this expertise. Here we present a reflection of the European situation and expertise, where most of the challenges we discuss are universal, anticipating that our suggestions will be useful internationally. We believe that one of the overriding goals of any Systems Biology education should be a student’s ability to phrase and communicate research questions in such a manner that they can be solved by the integration of experiments and modelling, as well as to communicate and collaborate productively across different experimental and theoretical disciplines in research and development

Effect of 12 Months of Recombinant Human Growth Hormone Replacement Therapy on Insulin Sensitivity in GH-Deficient Adults as Determined by Different Methods

BACKGROUND: Controversial results have been obtained in measuring insulin sensitivity (SI) during recombinant human growth hormone (rhGH) treatment in adult growth hormone deficient (GH-deficient) patients. AIMS: The aim of our study was to estimate SI before and during treatment using three different methods for quantifying insulin sensitivity in GH-deficient adults treated with rhGH. SETTINGS AND DESIGN: Twenty-one GH-deficient adults were treated with rhGH during 12 months. SI was estimated using Minimal model analysis, Homeostatic Model of Assessment (HOMA) and Quantitative Insulin Sensitivity Check Index (QUICKI) before and after 3, 6, 9 and 12 months of rhGH therapy. PATIENTS AND METHODS: Oral Glucose Tolerance Test (OGTT) and Frequently Sampled Intravenous Glucose Tolerance Test (FSIGT) were performed in each patient at respective time intervals. QUICKI and HOMA were calculated using basal values of glucose and insulin from FSIGT. Minimal model computer analysis was calculated from glucose and insulin data obtained during FSIGT. STATISTICAL ANALYSIS: Area under the curve for glucose, insulin and C-peptide were calculated using trapezoidal rule from OGTT data. Differences and correlations were tested using ANOVA for repeated measures, Wilcoxon's matched-paired test, paired t-test, Pearson's correlation and Bland Altman plot. RESULTS: There were no significant changes in SI using Minimal model analysis and QUICKI during rhGH treatment. On the contrary, HOMA analysis indicated significant deterioration in SI after 12 months of therapy. CONCLUSION: Our study did not demonstrate any changes in SI using Minimal model and QUICKI analysis, while there was significant increase in insulin resistance using HOMA model. We suggest that the choice of method for the determination of SI may influence the interpretation of results concerning the effect of rhGH therapy on SI in GH-deficient adults

Effect of 12 months of recombinant human growth hormone replacement therapy on insulin sensitivity in GH-deficient adults as determined by different methods

BACKGROUND: Controversial results have been obtained in measuring insulin sensitivity (SI) during recombinant human growth hormone (rhGH) treatment in adult growth hormone deficient (GH-deficient) patients. AIMS: The aim of our study was to estimate SI before and during treatment using three different methods for quantifying insulin sensitivity in GHdeficient adults treated with rhGH. SETTINGS AND DESIGN: Twenty-one GH-deficient adults were treated with rhGH during 12 months. SI was estimated using Minimal model analysis, Homeostatic Model of Assessment (HOMA) and Quantitative Insulin Sensitivity Check Index (QUICKI) before and after 3, 6, 9 and 12 months of rhGH therapy. PATIENTS AND METHODS: Oral Glucose Tolerance Test (OGTT) and Frequently Sampled Intravenous Glucose Tolerance Test (FSIGT) were performed in each patient at respective time intervals. QUICKI and HOMA were calculated using basal values of glucose and insulin from FSIGT. Minimal model computer analysis was calculated from glucose and insulin data obtained during FSIGT. STATISTICAL ANALYSIS: Area under the curve for glucose, insulin and C-peptide were calculated using trapezoidal rule from OGTT data. Differences and correlations were tested using ANOVA for repeated measures, Wilcoxon’s matched-paired test, paired t-test, Pearson’s correlation and Bland Altman plot. RESULTS: There were no significant changes in SI using Minimal model analysis and QUICKI during rhGH treatment. On the contrary, HOMA analysis indicated significant deterioration in SI after 12 months of therapy. CONCLUSION: Our study did not demonstrate any changes in SI using Minimal model and QUICKI analysis, while there was significant increase in insulin resistance using HOMA model. We suggest that the choice of method for the determination of SI may influence the interpretation of results concerning the effect of rhGH therapy on SI in GH-deficient adults

Metformin: Its emerging role in oncology

Metformin is considered, in conjunction with lifestyle modification, as a first-line treatment modality for type 2 diabetes mellitus (DM). Recently, several clinical studies have reported reduced incidence of neoplastic diseases in DM type 2 patients treated with metformin, as compared to diet or other antidiabetic agents. Moreover, in vitro studies have disclosed significant antiproliferative and proapoptotic effects of metformin on different types of cancer. Metformin acts by activating AMP-activated protein kinase (AMPK), a key player in the regulation of energy homeostasis. Moreover, by activating AMPK, metformin inhibits the mammalian target of rapamycin complex 1 (mTORC1) resulting in decreased cancer cell proliferation. Concomitantly, metformin induces activation of LKB1 (serine/threonine kinase 11), a tumor suppressor gene, which is required for the phosphorylation and activation of AMPK. These new encouraging experimental data supporting the anti-cancer effects of metformin urgently require further clinical studies in order to establish its use as a synergistic therapy targeting the AMPK/mTOR signaling pathway

The influence of Schiff base inclusion complexes with β-cyclodextrine on antibiotic production by Streptomyces hygroscopicus CH-7

A media consisting of isatin-Schiff bases and its inclusion complexes with beta-cyclodextrine was developed to maximize the production of antibiotics Hexaene H-85 and azalomycine B by Streptomyces hygroscopicus CH-7. The media With (-cyclodextrine inclusion complex of isatin-3-thiosemicarbazone resulted in the maximum antibiotics concentration of 493 ìg/cm3 for Hexaene H-85 and 191 ìg/cm3 for azalomycine B. The production of hexaene H-85 and azalomycine is higher when (-cyclodextrine complex is added as a nitrogen source, comparing to pure isatin-Schiff base. The maximum concentration of hexaene H-85 in medium with inclusion complex of isatin-Schiff base is 1.4-2.3 times higher than the basal medium. The maximum production of azalomycine is 2.1-3.4 times higher in media with inclusion complex of Schiff base. During the fermentation process, the nutrient media with (-cyclodextrine inclusion complexes with isatin-Schiff bases affect the strain morphology, since it is in the form of compact pellets, which are formed from short and long, branched filaments.Streptomyces hygroscopicus je soj poznat po produkciji različitih vrsta antibiotika i komercijalno važnih sekundarnih metabolita. Formiranje metabolita je rezultat mikrobioloških procesa u toku fermentacije i zavisi od nivoa biomase mikroorganizma, morfološkog profila kulture, kao i od ekoloških uslova. U cilju povećanja prinosa antibiotika, osnovna hranljiva podloga je redefinisana izmenom izvora azota, tako što su umesto sojinog brašna (10 g/dm3) dodati kompleksi Šifovih baza sa (-ciklodekstrinom (10 g/dm3). Dodatak kompleksa Šifovih baza sa bciklodekstrinom rezultirao je znatno povećanje koncentracije oba antibiotika. Maksimalna koncentracija heksaena H-85 je ostvarena na podlozi sa kompleksom izatin-3-tiosemikarbazona sa (-ciklodekstrinom i iznosila je 493 ìg/cm3, dok je za azalomicin B iznosila 191 ìg/cm3. Povećanje maksimalnih koncentracija antibiotika na podlogama sa kompleksima Schiff-ovih baza je iznosilo 1,4-2,3 puta za heksaen H-85, odnosno 2,1-3,4 puta za azalomicin B, u odnosu na osnovnu podlogu. U toku procesa fermentacije na hranljivim podlogama sa kompleksima Šifovih baza sa (-ciklodekstrinom, soj raste u obliku kompaktnih peleta, koji se formiraju od kratkih i dugih, razgranatih filamenata