Optimization of nutritional and environmental conditions for pyocyanin production by urine isolates of Pseudomonas aeruginosa

Pseudomonas aeruginosa (P. aeruginosa) is a highly pathogenic bacteria involved in numerous diseases among which, are urinary tract infections (UTIs). The pyocyanin secreted as a virulence factor by this bacterium has many beneficial applications but its high cost remains an obstacle for its widespread use. In this study, a total of fifty urine isolates were identified as P. aeruginosa. All strains produced pyocyanin pigment with a range of 1.3–31 µg/ml. The highest producer clinical strain P21 and the standard strain PA14 were used in optimization of pyocyanin production. Among tested media, king’s A fluid medium resulted in the highest yield of pyocyanin pigment followed by nutrient broth. Growth at 37 °C was superior in pyocyanin production than growth at 30 °C. Both shaking and longer incubation periods (3–4 days) improved pyocyanin production. The pyocyanin yield was indifferent upon growth of P21 at both pH 7 and pH 8. In conclusion, the optimum conditions for pyocyanin production are to use King’s A fluid medium of pH 7 and incubate the inoculated medium at 37 °C with shaking at 200 rpm for a period of three to four days.     

Measurement of cell proliferation by heavy water labeling

DNA replication occurs almost exclusively during S-phase of the cell cycle and represents a simple biochemical metric of cell division. Previous methods for measuring cell proliferation rates have important limitations. Here, we describe experimental protocols for measuring cell proliferation and death rates based on the incorporation of deuterium ((2)H) from heavy water ((2)H(2)O) into the deoxyribose moiety of purine deoxyribonucleotides in DNA of dividing cells. Label incorporation is measured by gas chromatography/mass spectrometry. Modifications of the basic protocol permit analysis of small cell samples (down to 2,000 cells). The theoretical basis and operational requirements for effective use of these methods to measure proliferation and death rates of cells in vivo are described. These methods are safe for use in humans, have technical and interpretation advantages over alternative techniques and can be used on small numbers of cells. The protocols enable definitive in vivo studies of the fraction or absolute number of newly divided cells and their subsequent survival kinetics in animals and humans.     

A high-fat diet rich in corn oil exaggerates the infarct size and memory impairment in rats with cerebral ischemia and is associated with suppressing osteopontin and Akt,and activating GS3Kβ, iNOS,and NF-κB

Journal of Physiology and Biochemistry - The increase in osteopontin (OPN) levels after stroke induces neural protection by activating Akt signaling and inhibiting GS3Kβ, iNOS, and NF-κB....     

COX-2 polymorphisms − 765G→C and − 1195A→G and hepatocellular carcinoma risk

Cyclooxygenase-2 (COX-2) is overexpressed in hepatocellular carcinoma (HCC) and considered to play a role in hepatic carcinogenesis. Our aim was to examine the associations between polymorphisms in COX-2 − 765G→C and − 1195A→G and risk of HCC. We conducted a case–control study including 120 patients with HCC and 130 age- and gender-matched controls. Genotypes of the COX-2 polymorphisms − 765G→C and − 1195A→G were determined by polymerase chain reaction-based restriction fragment length polymorphism. No significant difference was observed in the genotype distribution of the − 765G→C polymorphism between patients and controls. The − 1195AA genotype was associated with an increased risk of developing HCC (OR, 2.5; 95%CI, 1.18–5.37). The A allele was present significantly more often in HCC patients (OR 1.5; 95%CI, 1.05–2.14). In conclusion, our results demonstrated that the − 1195AA genotype and A allele have an important role in HCC risk in Egyptian patients.     

Preliminary findings of age and male sexual characteristics andand potential effect to semen characteristics and cryopreservation of the critically endangered Bornean orangutan in Malaysia

Primates - Bornean orangutan is a critically endangered non-human primate; however, the threat of extinction is not merely from poaching and habitat loss. Orangutan survival is also threatened by...     

Lipoplex size determines lipofection efficiency with or without serum

In order to identify factors affecting cationic Iiposome-mediated gene transfer, the relationships were examined among cationic liposome/DNA complex (lipoplex)-cell interactions, lipoplex size and lipoplex-mediated transfection (lipofection) efficiency. It was found that lipofection efficiency was determined mainly by lipoplex size, but not by the extent of lipoplex-cell interactions including binding, uptake or fusion. In addition, it was found that serum affected mainly lipoplex size, but not lipoplex-cell interactions, which effect was the major reason behind the inhibitory effect of serum on lipofection efficiency. It was concluded that, in the presence or absence of serum, lipoplex size is a major factor determining Iipofection efficiency. Moreover, in the presence or absence of serum, lipoplex size was found to affect lipofection efficiency by controlling the size of the intracellular vesicles containing lipoplexes after internalization, but not by affecting lipoplex-cell interactions. In addition, large lipoplex particles showed, in general, higher lipofection efficiency than small particles. These results imply that, by controlling lipoplex size, an efficient lipid delivery system may be achieved for in vitro and in vivo gene therapy.     

High-Performance Dye-Sensitized Solar Cells Based on Morphology-Controllable Synthesis of ZnO–ZnS Heterostructure Nanocone Photoanodes

High-density and well-aligned ZnO–ZnS core–shell nanocone arrays were synthesized on fluorine-doped tin oxide glass substrate using a facile and cost-effective two-step approach. In this synthetic process, the ZnO nanocones act as the template and provide Zn²⁺ ions for the ZnS shell formation. The photoluminescence spectrum indicates remarkably enhanced luminescence intensity and a small redshift in the UV region, which can be associated with the strain caused by the lattice mismatch between ZnO and ZnS. The obtained diffuse reflectance spectra show that the nanocone-based heterostructure reduces the light reflection in a broad spectral range and is much more effective than the bare ZnO nanocone and nanorod structures. Dye-sensitized solar cells based on the heterostructure ZnO–ZnS nanocones are assembled, and high conversion efficiency (η) of approximately 4.07% is obtained. The η improvement can be attributed primarily to the morphology effect of ZnO nanocones on light-trapping and effectively passivating the interface surface recombination sites of ZnO nanocones by coating with a ZnS shell layer.     

Different subcellular localizations and functions of Arabidopsis myosin VIII

Background  

Myosins are actin-activated ATPases that use energy to generate force and move along actin filaments, dragging with their tails different cargos. Plant myosins belong to the group of unconventional myosins and Arabidopsis myosin VIII gene family contains four members: ATM1, ATM2, myosin VIIIA and myosin VIIIB.     

Fatigue effect on cross-talk in mechanomyography signals of extensor and flexor forearm muscles during maximal voluntary isometric contractions

Objective:This paper presents the analyses of the fatigue effect on the cross-talk in mechanomyography (MMG) signals of extensor and flexor forearm muscles during pre- and post-fatigue maximum voluntary isometric contraction (MVIC).Methods:Twenty male participants performed repetitive submaximal (60% MVIC) grip muscle contractions to induce muscle fatigue and the results were analyzed during the pre- and post-fatigue MVIC. MMG signals were recorded on the extensor digitorum (ED), extensor carpi radialis longus (ECRL), flexor digitorum superficialis (FDS) and flexor carpi radialis (FCR) muscles. The cross-correlation coefficient was used to quantify the cross-talk values in forearm muscle pairs (MP1, MP2, MP3, MP4, MP5 and MP6). In addition, the MMG RMS and MMG MPF were calculated to determine force production and muscle fatigue level, respectively.Results:The fatigue effect significantly increased the cross-talk values in forearm muscle pairs except for MP2 and MP6. While the MMG RMS and MMG MPF significantly decreased (p<0.05) based on the examination of the mean differences from pre- and post-fatigue MVIC.Conclusion:The presented results can be used as a reference for further investigation of cross-talk on the fatigue assessment of extensor and flexor muscles’ mechanic.     

Effects of irradiance and spectral quality on seedling development of two Southeast Asian Hopea species

 Seedling developmental responses to understory shade combine the effects of reductions in irradiance and changes in spectral quality. We studied the seedling development of two Southeast Asian dipterocarp trees in response to differences in irradiance (photosynthetic photon flux density, PPFD) and spectral quality (red to far-red ratio, R:FR). The two species, Hopea helferei and H. odorata, are taxonomically closely related but differ in their ecological requirements; H. helferei is more drought-tolerant and typically grows in more open habitats. Seedlings were grown in six different replicated shadehouse treatments varying in percentage of solar PPFD and R:FR. The two species differed in the influence of light variables on most seedling characters, particularly for final height, internode distance, branch/trunk internodes, stem length/mass, leaf area/stem length, petiole length, and growth/mol of photons received. Most of the characters in both taxa were primarily influenced by PPFD, but spectral quality also influenced some characters – more so for H. odorata. The latter species grew more rapidly, particularly in the low PPFD treatments, and its leaves were capable of higher photosynthesis rates. However, growth in H. helferei was not reduced in direct sunlight. The growth of this taxon may be constrained by adaptations, particularly in leaves, for drought tolerance. Received: 14 April 1996 / Accepted: 8 October 1996