Evidence-based antibiotic therapy of diabetic foot infections

In addition to proper cleansing, debridement and local wound care, foot infections in diabetic patients require carefully selected antibiotic therapy. Serious infections necessitate hospitalization for initial parenteral broad-spectrum antibiotic therapy. Appropriately selected patients with mild infections can be treated as outpatients with oral (or even topical) therapy. Initial antibiotic selection is usually empirical, but definitive therapy may be modified based on culture results and the clinical response. Therapy should nearly always be active against staphylococci and streptococci, with broader-spectrum agents indicated if Gram-negative or anaerobic organisms are likely. In infected foot tissues levels of most antibiotics, except fluoroquinolones, are often subtherapeutic. The duration of therapy ranges from a week (for mild soft tissue infections) to over 6 weeks (for osteomyelitis). Recent antibiotic trials have shown that several intravenously or orally administered agents are effective in treating these infections, with no one agent or combination emerging as optimal. Suggested regimens based on the severity of infection are provided.     

Baseline susceptibility of western corn rootworm (Coleoptera: Chrysomelidae) to clothianidin

Abstract:  Western corn rootworm, Diabrotica virgifera virgifera LeConte, neonate susceptibility to clothianidin, a contact and systemic neonicotinoid insecticide, was determined from both laboratory and field-collected populations. Neonates were exposed to filter paper treated with increasing clothianidin concentrations and mortality was evaluated after 24 h. Additionally, two populations were exposed to an artificial diet which was surface treated with clothianidin. Although larvae were five- to six-fold more sensitive to treated diet, results with treated filter paper were more reliable in terms of control mortality and required much less manipulation of rootworm larvae. Therefore, initial baseline comparisons were conducted using the filter paper assays. The variation among populations exposed to treated filter paper was generally low, 4.4-fold among laboratory populations tested; however, there was a 14.5-fold difference in susceptibility among all populations tested. In general, clothianidin was very toxic to rootworm neonates, with LC₅₀ values ranging from 1.5 to 21.9 ng/cm². These results indicate the practicability and sensitivity of the paper filter disc assay to establish baseline susceptibility levels, which is an essential first step in resistance management. A baseline response provides a reference for tracking shifts in susceptibility following commercialization of a control agent so that early changes in susceptibility can be detected.     

Effects of acetic acid treatment on plant chromosome structures analyzed by atomic force microscopy

Acetic acid treatment has been frequently used to remove cellular contaminants from plant chromosome samples for structural analyses by scanning electron microscopy and atomic force microscopy (AFM). We evaluated the effects of various concentrations of acetic acid treatments on barley chromosome structures by using AFM. The long-term 45% acetic acid treatment significantly damaged the chromosome structures, although the treatment effectively removed the cellular contaminants. On the other hand, the treatment with 15% acetic acid could not obtain sufficiently clean chromosome samples and the chromosome surface structures could not be observed. In contrast, we obtained clean chromosome preparation without severe damage by using an intermediate concentration (30%) of acetic acid treatment. In the centromeric region, we could observe fiber structures with a width of 100 nm, which were composed of ca. 50-nm granules and aligned to the axes of chromosomes. Thus, AFM analysis of chromosomes appropriately treated with acetic acid will provide important insights into the organization of higher-order structures of plant chromosomes.     

pH, Redox, and oxygen microprofiles in rhizosphere of bulrush (Scirpus validus) in a constructed wetland treating municipal wastewater

Microenvironmental studies regarding plant oxygen release in a wastewater environment are important to understand the principles of constructed wetlands for wastewater treatment. pH, oxidation reduction potential (ORP), and dissolved oxygen (DO) microprofiles for the lateral and main roots of the bulrush (Scirpus validus) in a vertical flow constructed wetland fed with municipal wastewater were measured using microelectrode techniques. pH was found to be low (6.91-6.98) near the lateral root surface, indicating possible nitrification or H(+) extrusion. The ORP at the lateral root surface was between +250 and +317 mV and gradually reached the bulk solution ORP (+14 to -54 mV) at a radial distance of approximately 4,750 microm. DO values at the lateral root surface varied from 0.64-2.04 mg L(-1) as bulk biochemical oxygen demand (BOD) changed from 24 to 1,267 mg L(-1). DO at the lateral root surface and the thickness of the oxygen layer around the root marginally increased with an increase in bulk BOD, while ORP at the lateral and main root surface decreased. pH and DO values did not change near the main root and had the bulk solution values. The results of this study provide insights into root-induced microenvironments and would be helpful for the quantification of the total amount of oxygen contributed by plants in constructed wetlands.     

Haloalkane hydrolysis by Rhodococcus erythropolis cells: comparison of conventional aqueous phase dehalogenation and nonconventional gas phase dehalogenation

Biofiltration of air polluted by volatile organic compounds is now recognized by the industrial and research communities as an effective and viable alternative to standard environmental technologies. Whereas many studies have focused on solid/liquid/gas biofilters, there have been fewer reports on waste air treatment using other biological processes, especially in a solid/gas biofilter. In this study, a comparison was made of the hydrolysis of halogenated compounds (such as 1-chlorobutane) by lyophilized Rhodococcus erythropolis cells in a novel solid/gas biofilter and in the aqueous phase. We first determined the culture conditions for the production of R. erythropolis cells with a strong dehalogenase activity. Four different media were studied and the amount of 1-chlorobutane was optimized. Next, we report the possibility to use R. erythropolis cells in a solid/gas biofilter in order to transform halogenated compounds in corresponding alcohols. The effect of experimental parameters (total flow into the biofilter, thermodynamic activity of the substrates, temperature, carbon chain length of halogenated substrates) on the activity and stability of lyophilized cells in the gas phase was determined. A critical water thermodynamic activity (a(w)) of 0.4 is necessary for the enzyme to become active and optimal dehalogenase activity for the lyophilized cells is obtained for an a(w) of 0.9. A temperature of reaction of 40 degrees C represents the best compromise between stability and activity. Activation energy of the reaction was determined and found equal to 59.5 KJ/mol. The pH effect on the dehalogenase activity of R. erythropolis cells was also studied in the gas phase and in the aqueous phase. It was observed that pH 9.0 provided the best activity in both systems. We observed that in the aqueous phase R. erythropolis cells were less sensitive to the variation in pH than R. erythropolis cells in the gas phase. Finally, the addition of volatile Lewis base (triethylamine) in the gaseous phase and the action of the lysozyme in order to permeabilize the cells was found to be highly beneficial to the effectiveness of the biofilter.     

A new VFA sensor technique for anaerobic reactor systems

A key parameter for understanding and controlling the anaerobic biogas process is the concentration of volatile fatty acids (VFA). However, this information has so far been limited to off-line measurements using labor-intensive methods. We have developed a new technique that has made it possible to monitor VFA on-line in one of the most difficult media: animal slurry or manure. A novel in situ filtration technique has made it possible to perform microfiltration inside a reactor system. This filter enables sampling from closed reactor systems without large-scale pumping and filters. Furthermore, due to its small size it can be placed in lab-scale reactors without disturbing the process. Using this filtration technique together with commercially available membrane filters we have constructed a VFA sensor system that can perform automatic analysis of animal slurry at a frequency as high as every 15 minutes. Reproducibility and recovery factors of the entire system have been determined. The VFA sensor has been tested for a period of more than 60 days with more than 1,000 samples on both a full-scale biogas plant and lab-scale reactors. The measuring range covers specific measurements of acetate, propionate, iso-/n-butyrate and iso-/n-valerate ranging from 0.1 to 50 mM (6-3,000 mg). The measuring range could readily be expanded to more components and both lower and higher concentrations if desired. In addition to the new VFA sensor system, test results from development and testing of the in situ filtration technique are being presented is this article.     

Further studies on thermal treatment of two-cell stage embryos to produce complete embryonic stem-cell-derived mice by cell-aggregation methods

Employing aggregation techniques with two embryonic sources, one from two-cell stage embryos treated by thermal stimulation and the other from mouse embryonic stem (ES) cells that had been obtained from a feeder layer, simple and most effective methods of producing a complete generation of mice from ES cells were explored. Although thermal treatment affected embryos at various developmental stages, the embryos at the two-cell stage of development were selected because of the remarkably reduced number of cells present in the inner cell mass (ICM) at blastocyst stage after thermal conditioning. Under these conditions, a combination of thermally treated host embryos and an aggregated ES cell-clump was found to produce a high rate of live newborns by natural delivery. That the newborns were completely derived from ES cells was checked by two criteria: microsatellite analysis and coat color analysis. Importantly, all of these mice were healthy and fertile. The aggregation techniques reported here might well be applied to other animal species whose ES cells form stable colonies on a feeder layer.     

Proliferation,maturation and germination of Castanea sativa Mill. Somatic embryos originated from leaf explants

Experiments were performed to determine the influence of proliferation medium on the maintenance of embryogenic competence and on repetitive embryogenesis in Castanea sativa Mill. somatic embryos derived from leaf explants. Somatic embryo proliferation was carried out by both direct secondary embryogenesis and by the culture of nodular callus tissue originated from cotyledons of somatic embryos. Both systems led to the production of cotyledonary somatic embryos on Murashige and Skoog proliferation medium supplemented with 0.1 mg l-1 benzyladenine and 0.1 mg l-1 naphthaleneacetic acid. Carbon source and concentration had a marked influence on maturation and subsequent germination ability of chestnut somatic embryos. Plantlet conversion was achieved in embryos matured on media with 6 % sucrose, and on 3 or 6 % maltose, whereas mean shoot length, root length and leaf number of produced plants were not significantly affected by these maturation media. Overall, the best results were obtained with 3 % maltose-matured somatic embryos, giving rise to 6 % plant recovery in addition to 33 % of embryos exhibiting only shoot development. The application of a 2-month cold treatment at 4 degrees C to somatic embryos matured on medium with 3 % maltose was necessary for achieving plant conversion, while partial desiccation did not appear to influence this response. A total of 39 % of embryos eventually produced plants either through conversion to plantlets or indirectly through rooting of shoots. Shoots formed by somatic embryos could be excised, multiplied and rooted following the micropropagation procedures previously developed for chestnut.     

Chilling stability of microtubules in root-tip cells of cucumber

The chilling stability of microtubules was investigated in root-tip cells of cucumber (Cucumis sativus L.) using immunofluorescence labeling and a confocal laser scanning microscope. After low temperature (4°C) treatment for 5 h, we found not only chilling-stable cortical microtubules under the plasma membrane of the root-tip cells, but also chilling-stable punctate microtubules in the cytoplasm, which might be the microtubules associated with organelles. 6-Dimethylaminopurine (6-DMAP), an inhibitor of protein kinase, reduced the chilling stability of the cortical microtubules in the cells. When the root-tip cells were restored to normal growth temperature (28°C), the recovery of the microtubules seemed to be closely associated with the microtubules still remaining in these cells after chilling treatment.Abbreviations 6-DMAP 6-Dimethylaminopurine - DMSO Dimethyl sulfoxide - FITC Fluorescein isothiocyanate - MTOCs Microtubule-organizing centers - PPB Pre-prophase bandCommunicated by H. WangJ.-L. Zhao and X.-J. Li are considered joint first authors     

Influence of alkali-freezing treatment on the solid state structure of chitin

Chitin was soaked in frozen sodium hydroxide for further modification. The solid state structural changes of the resulting chitin powders were studied by X-ray diffraction (XRD) and infrared spectroscopy measurements. During the alkali-freezing process, the crystal space parameters of chitin changed, and the order of the hydrogen bonds of chitin was modified. The study explains how the treatment is beneficial for further modification of chitin. The crystallinity of chitin was assessed according to XRD results. It decreased by half after the alkali-freezing treatment for the first 3 days, and then a few changes happened on the following days while the crystallinity of chitin was kept in the scale of 13.5-18%. That means that the alkali-freezing treatment of chitin for several days is suitable and sufficient.