Biomedical subjects

L S Bell

Publications and source records attributed to L S Bell.

12 recordsLinked to original sources

PubMed2003

A sequential zero valent iron and aerobic biodegradation treatment system for nitrobenzene.

The remediation of nitroaromatic contaminated groundwater is sometimes difficult because nitroaromatic compounds are resistant to biodegradation and, when they do transform, the degradation of the products may also be incomplete. A simple nitroaromatic compound, nitrobenzene, was chosen to assess the feasibility of an in situ multi-zone treatment system at the laboratory scale. The proposed treatment system consists of a zero valent granular iron zone to reduce nitrobenzene to aniline, followed by a passive oxygen release zone for the aerobic biodegradation of the aniline daughter product using pristine aquifer material from Canadian Forces Base (CFB) Borden, Ontario, as an initial microbial source. In laboratory batch experiments, nitrobenzene was found to reduce quickly in the presence of granular iron forming aniline, which was not further degraded but remained partially sorbed onto the granular iron surface. Aniline was found to be readily biodegraded with little metabolic lag under aerobic conditions using the pristine aquifer material. A sequential column experiment, containing a granular iron reducing zone and an aerobic biodegradation zone, successively degraded nitrobenzene and then aniline to below detection limits (0.5 microM) without any noticeable reduction in hydraulic conductivity from biofouling, or through the formation of precipitates.

Bacteria, Aerobic↗

PubMed2001

Determining isotopic life history trajectories using bone density fractionation and stable isotope measurements: a new approach.

A number of recent studies have attempted to trace diet at different stages of an individual's life by comparing isotope ratios of bone from different gross anatomical sites within the skeleton. In this study we develop this approach further by separating bone of differing mineral densities within one skeletal element, where each density fraction represents a different period of time. Isotope ratios are measured for these fractions. Each density fraction represents a period of bone formation and maturation, where younger (more recently formed) bone is less well-mineralized and therefore less dense than relatively older packets of bone. In an adult, bone is therefore able to partition approximately the last 15 years of life. Bone fractions were recovered by stepped ultracentrifugation in a series of organic solvents of increasing density, and then collagen was recovered by decalcification in dilute acid, and stable carbon isotope ratios ((13)C/(12)C) were measured. Bone density microstructure was checked for bacterial remodelling using backscattered electron imaging in a scanning electron microscope. Our results indicate that the bone density fractionation method is applicable to archaeological material, here extending to a maximum of 5,000 years BP, and that collagen can successfully be extracted from such fractions. The carbon isotope values for bone fractions of different densities patterned out as expected in one modern control bone and in specimens from five archaeological human skeletons, including three precolonial hunter-gatherers and two 18th/19th century individuals. The latter two are known (from previous assessments) to have undergone marked changes in diet during their lifetimes. Postmortem alteration was evident in some of the specimens examined. The bone density fractionation approach has allowed greater resolution of diet than has hitherto been possible and has provided access to the elusive last years and months of an individual's life.

Adult↗

PubMed1996

The speed of post mortem change to the human skeleton and its taphonomic significance.

The aim of this study was to assess the potential speed of post mortem alteration to skeletal microstructure by examining human material drawn from differing environmental contexts and time periods. The material was taken from terrestrial, intertidal and lacustrine contexts and extended over a range of 3 months to 83 years post mortem. The examination was conducted using backscattered electron imaging which provided information on microstructure and relative density. The results from this study have significantly brought forward the time of known onset for post mortem alteration for 3 morphological types of microstructural change, the earliest of which was 3 months post mortem. The contribution of the depositing environment was also shown to influence significantly the microstructural/ morphological type of post mortem alteration. It is hypothesized that microstructural changes to bone could occur within days of death as a result of endogenous bacterial migration to the skeleton. Further studies are required to establish definitively the earliest moment that such change can occur prior to skeletonisation.

Adult↗

PubMed1991

Analysis of ancient bone DNA: techniques and applications.

The analysis of DNA from ancient bone has numerous applications in archaeology and molecular evolution. Significant amounts of genetic information can be recovered from ancient bone: mitochondrial DNA sequences of 800 base pairs have been amplified from a 750-year-old human femur by using the polymerase chain reaction. DNA recovery varies considerably between bone samples and is not dependent on the age of the specimen. We present the results of a study on a small number of bones from a mediaeval and a 17th-century cemetery in Abingdon showing the relation between gross preservation, microscopic preservation and DNA recovery.

Bone and Bones↗

PubMed1990

Conducting a third-party reimbursement survey: experience of the Connecticut Nutrition Services Payment Systems Committee.

Third-party reimbursement (TPR) has emerged as a crucial issue for dietetics in the past decade. To investigate the level of TPR being obtained by individuals receiving nutrition services from registered dietitians in ambulatory settings, the Connecticut Nutrition Services Payment Systems (NSPS) Committee conducted an audit. Sixty survey packets were distributed to consulting dietitians in private practice and to dietitians in outpatient nutrition clinics. Twenty dietitians participated in the audit process, providing 99 client responses to the survey. Sixty-seven percent of clients submitted the charges for nutrition services to their insurance companies, but only 17% received reimbursement for the claims submitted. This audit process raised the level of awareness of the state membership regarding the need to aggressively pursue TPR for nutrition services at all levels, and it provided a model for dietitians to use to conduct periodic audits and assess TPR being received by their clients.

Connecticut↗

PubMed1989

Development of a productivity index to increase accountability of ambulatory nutrition services.

The development of a system to assess the productivity of ambulatory nutrition services presented many challenges, including variations in provider settings and in the record-keeping techniques of ambulatory nutrition personnel. A model to measure the productivity of ambulatory nutrition specialists at a large urban teaching hospital was devised and was defined by the following equation: Patient/time productivity index = [(extended visits X 2) + (brief visits X 1) + (weigh-ins X 0.5) + (telephone consults X 0.25) + (group class census X 0.25)] divided by number of hours worked. Information obtained from this productivity measurement has been used to evaluate and improve patient scheduling and the organization of functions in various ambulatory nutrition settings. A productivity award based on the productivity index and distributed monthly has provided an incentive for all ambulatory nutrition specialists to streamline operations and maximize efficiency. The patient/time productivity index has been incorporated into performance reviews of ambulatory nutrition specialists as an objective measure of compliance with expectations. When used in conjunction with quality assurance techniques such as chart audits and patient satisfaction questionnaires, the patient/time productivity index can be a useful tool for management to maximize the quality and efficiency of ambulatory nutrition services.

Dietary Services↗

PubMed1988

STM imaging of molecular collagen and phospholipid membranes.

The application of STM to biological materials has been limited by poor conductivity, sample geometry and stability of biological materials. In this paper we describe an STM study of the monomeric helical forms of collagen, a stable, conductive and widely prevalent structural protein. We have also used STM to image artificial Langmuir DPE (dipalmitoyl phosphatidyl ethanolamine) phospholipid membranes. Both molecular collagen and the phospholipid membranes were dried in air on highly oriented pyrolytic graphite (HOPG). Our STM images of collagen dried on HOPG reveal strands 15 A in diameter with a periodicity of about 30 A which correlates with that known to occur in collagen. Spikes which periodically protrude from strands in our STM images of collagen appear to represent pyrrolidine ring structures in the amino acids proline and hydroxyproline. Thus, we report the first STM imaging of native biomolecules revealing intramolecular details and what appear to be specific amino acids. STM imaging of phospholipid membranes show a lattice pattern with densities spaced approximately 4.5 A apart. These are thought to represent individual phospholipid molecules in an artificial membrane formed on the HOPG. We believe STM and its related technologies will have great future utility in biomolecular studies.

Animals↗

PubMed1987