Evidence of perchlorate (ClO4-) reduction in plant tissues (poplar tree) using radio-labeled 36ClO4-

Phytoremediation of perchlorate (ClO4) by poplar trees Populus deltoidex nigrawas investigated using small cuttings growing in hydroponic Hoagland solution and plant tissue cultures, consisting of spherical photosynthetic cell aggregates (i.e. nodules) developing in Murashige and Skoog culture medium. Both plants and nodules were grown under a 16 h/8 h photoperiod cycle and under sterile conditions. Degradation experiments, performed by the incubation of pregrown plants and nodules in the presence of 36Cl radio-labeled ClO4- (25 mg L(-1)), showed a reduction of the initial ClO4- concentration in the solution of about 50% after 30 d of incubation. Analysis of the distribution of radioactivity in different plant fractions indicated that 27.4% of the total was translocated to the leaves, while 66.9% remained in the solution. Very little radioactivity (less than 3.0%) was detected in the other parts of the plants. 32.0% of the radioactivity recovered in the solution was shown to consist of 36Cl- and 68.0% of nontransformed 36ClO4-. The radioactivity recovered in the leaf extracts was distributed as chloride (36Cl-) (1.6% of the total), chlorite (36ClO2-) (2.4%), chlorate (36ClO3-) (4.8%), nontransformed 36ClO4- (21.6%), and an unidentified organic compound (1.4%). The radioactivity recovered in the solution containing submerged nodules consisted of 36Cl- (6.4% of the total), 36ClO3- (1.3%), and nontransformed 36ClO4- (51.5%). Radioactivity detected in the nodule extracts was distributed as 36Cl- (2.0% of the total), 36ClO2- (5.2%), 36ClO3- (6.4%), 36ClO4- (22.7%), and an unidentified organic compound (0.5%). These results provide evidence of perchlorate reduction inside poplar tree tissues. 36ClO4- is partially reduced to 36ClO3-, 36ClO2-, and 36Cl-.     

Microgravity materials and life sciences research applications of digital holography

We investigate the utility of digital holographic interferometry for analyzing gravity-dependent mass transport phenomena as applicable to materials and life science research topics. Digital holography is useful for measurement of parameters that introduce phase changes in light traversing the material of interest, such as temperature or concentration variations in an aqueous environment. We have constructed, tested, and verified a compact, portable digital holographic monitor (DHM) suitable for characterization of transparent samples. It has proved useful for the study of systems such as protein crystal growth solutions and has been proposed for further application into studies involving microbial metabolism. The DHM is also sufficiently rugged for field operation in challenging environments a s may be encountered in a spacecraft or industrial setting. We discuss some system capabilities and limitations.     

The use of the portable ergonomic observation method (PEO) to monitor the sitting posture of schoolchildren in the classroom

Contrary to common belief, back pain amongst young people is a frequent phenomenon. Epidemiological studies have found high prevalence rates of back pain amongst schoolchildren. The investigation reported here aims to validate children's self-reporting and the observation of sitting postures to establish the intensity, duration and frequency of exposure in the classroom. The sitting postures of 18 children were recorded using three methods, the portable ergonomic observation method (PEO), video analysis and self-report. The three methods were compared. PEO was significantly correlated with video analysis of the sitting postures after development of the method. Self-report was not significantly correlated with video analysis of the sitting postures. Therefore PEO was selected as the main observation tool in further analysis of children's sitting posture in schools in South-East England as part of a large research programme investigating back pain amongst schoolchildren.     

Customization of a Commercially Available Prep Scale SFC System to Provide Enhanced Capabilities

Preparative Scale Supercritical Fluid Chromatography is emerging as a powerful alternative to HPLC for the purification and separation of complex chemical reaction mixtures. Advantages include greatly reduced solvent usage (and thus lower cost and environmental impact), higher throughput, and in some cases higher resolution. While there are commercially available prep SFC instruments, none currently offer all the features desired by many medicinal chemists engaged in the drug discovery process. These include: the ability to collect an unlimited number of fractions per sample with high recovery and negligible carryover, fully automated capacity to collect several hundred fractions, and the ability to collect fractions into the same disposable test tubes and racks which are already employed in HPLC. This article describes the customization of a preparatory scale SFC system purchased from Berger Instruments, Inc., Newark, DE. (a subsidiary Mettler-Toledo International, Inc., of Greifensee, Switzerland) in order to provide these capabilities.     

Heparin-like polymers derived from dextran enhance colonic anastomosis resistance to leakage

OBJECTIVE: To determine whether a short computer interview could be used in place of a full diagnostic interview to obtain psychiatric diagnoses, the authors examined the short interview's sensitivity, specificity, and diagnostic agreement with the full interview. METHODS: Patients recently discharged from a university psychiatric service were interviewed in two back-to-back sessions, one in which a full diagnostic interview was used and the other in which a short computer interview was used. Based on diagnoses derived from both interviews, the sensitivity and specificity of the short interview and kappa values reflecting the diagnostic agreement of the two interviews were calculated. RESULTS: The short interview had high sensitivity and specificity and excellent diagnostic agreement with the full interview for most disorders. It also had a significantly shorter administration time. However, it missed a substantial percentage of cases of generalized anxiety disorder and misclassified as in remission a substantial proportion of patients with active cases of post-traumatic stress disorder. CONCLUSIONS: With few exceptions, the short interview may be substituted for the full interview when missing an active case is not important or when a count of individual symptoms and subtyping of disorders are not needed. Such uses include screening subjects for inclusion in a study and obtaining an overview of a patient's lifetime psychiatric status.     

Species-dependent enantioselective glucuronidation of carprofen

1. The stereoselective glucuronidation of carprofen, a non-steroidal anti-inflammatory drug, was investigated in vitro using microsomes prepared from liver of different species (rat, dog, horse, sheep and man) or UGT2B1 expressed in fibroblasts. 2. The Km towards the drug was very similar among these species and for the two enantiomers, whereas the Vmax varied substantially according to the animal used. The rat exhibited a high stereoselective glucuronidation whereas other species, including man, presented a low stereoselectivity. The R-enantiomer was glucuronidated at a more efficient rate than its enantiomorph, and was a better substrate (in terms of Vmax/Km). 3. To explain the enantioselective disposition of carprofen in man and in the different species, the ratio of the enzymatic efficacies (Vmax/Km) were compared with the ratio of the pharmacokinetic parameters AUCs. The basic hypothesis that the intrinsic clearance reflect the enantioselective behaviour of carprofen seemed substantiated when we focused on man and rat glucuronidation, but the in vivo-in-vitro correlation was not possible in other species. 4. In conclusion, the chiral pharmacokinetics of carprofen is less dependent on the stereoselective glucuronidation than other stereoselective processes such as protein binding of carprofen, enzymatic hydrolysis, or renal elimination of glucuronides.     

High-temperature coupling of high-speed GPC with continuous viscometry. II. Ethylene–vinyl acetate copolymers

An application of the high temperature coupling of a gel permeation chromatograph with a home-made continuous viscometric detector is described. It concerns the comprehensive characterization of ethylene–vinyl acetate copolymers. Suitable chromatographic conditions are chosen to enable a correct use of the universal calibration concept. Through analysis of poly(vinyl acetate) fractions and commercial polyethylene samples, a comparison is made with the results of classical measurements. Average molecular weights as well as intrinsic viscosity appear to be in good agreement within experimental error, which proves the system for the characterization of random ethylene–vinyl acetate copolymers. In attempting to obtain a reliable estimate of long chain branching frequency λ, a series of commercial samples has been selected, with the vinyl acetate weight fraction within the range 0–45%. As a rule, experimental viscosity law exhibits two parts, a straight line with a Mark–Houwink exponent 0.7 in the low molecular weight region and a curvature, well smoothed by a third-degree polynomial regression. Consequently, long chain branching does not appear before a limiting molecular weight of about 50,000. Beyond this limit, λ is 0.5 × 10^?4, with no dependence on molecular weight, which resembles low density polyethylene.     

Update on methodology topics

The following column on methodology topic was prepared by AOCS Technical Director Dave Berner. Questions on these or other topics concerning analytical methodology of fats and oils or related products may be directed to Dave Berner, AOCS, PO Box 3489, Champaign, IL 61821-0489, USA