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Biomedical subjects

C Hill

Publications and source records attributed to C Hill.

360 records · Page 20Linked to original sources
PubMedDate not supplied

Results of the international Pu-2000 exercise for plutonium isotopic composition measurements.

An international comparison for plutonium isotopic composition measurement, known as the Pu-2000 exercise, was organized by the ESARDA NDA-WG (European Safeguards Research and Development Association, Working Group on Techniques and Standards for Non-Destructive Assay). The aim of this comparison was to test X- and gamma-ray spectrometry methods over a large range of isotopic ratios. These methods are based on the complex analysis of several X- and gamma-rays in the KX region of the plutonium spectrum and also in the 120-700 keV energy range. The results obtained by the participants with their corresponding uncertainties are presented in this document and compared to the declared values. The main conclusions of the work are also given. No important bias due to an inadequate knowledge of the nuclear data for plutonium isotopes was observed.

International Cooperation↗
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Characterisation of reference materials for radioactivity with assigned values traceable to the SI units.

The Institute for Reference Materials and Measurements participates in an IAEA co-ordinated project to upgrade Analytical Quality Control Services intercomparison materials to reference materials. The principal objective is to ensure that assigned property values are traceable to the International System of Units. General principles and practical mechanisms for achieving this traceability are described.

Journal Article↗
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Validation of methods for the determination of radium in waters and soil.

This article describes the advantages and disadvantages of several analytical methods used to prepare the alpha-particle source. As a result of this study, a new method combining commercial extraction and ion chromatography prior to a final co-precipitation step is proposed. This method has been applied and validated on several matrices (soil, waters) in the framework of international intercomparisons. The integration of this method in a global procedure to analyze actinoids and radium from a single solution (or digested soil) is also described.

Alpha Particles↗
PubMedDate not supplied

Aspects of sample preparation for the determination of actinoids in soil.

In the frame of the re-certification measurements of the IAEA-375 soil reference material the activity concentration of four actinoids (U, Th, Pu and Am) was determined. The method is based on microwave digestion or aqua regia leaching, separation by extraction chromatography and alpha-particle counting source preparation by co-precipitation or electro-deposition. This article describes some of the problems encountered during the validation of the sample preparation method and their solutions.

Actinoid Series Elements↗
PubMedDate not supplied

Predicting the effect of livestock inputs of E. coli on microbiological compliance of bathing waters.

Three alternative approaches to predicting delivery of faecal indicators from livestock sources to surface water in the catchment of the River Irvine, Ayrshire, Scotland, are described. These are a soil transport model which assumes all E. coli are transported through the soil, a regression model using observed E. coli concentrations in surface waters, and a distributed catchment model (PAMIMO). Each of these is linked to a simple group of equations describing inputs of E. coli from livestock to land, transport and inactivation in the river Irvine and mixing and inactivation in the sea. The models predict E. coli content of bathing water for Irvine beach. The regression model gives the best predictions of bathing water quality. The low values predicted by the soil transport model suggests that preventing surface runoff of faecal indicators from livestock would provide an adequate solution to the problem of bathing water contamination.

Animals↗
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Potential of bacteriocin-producing lactic acid bacteria for improvements in food safety and quality.

Lactic acid bacteria (LAB) have been used for centuries in the fermentation of a variety of dairy products. The preservative ability of LAB in foods is attributed to the production of anti-microbial metabolites including organic acids and bacteriocins. Bacteriocins generally exert their anti-microbial action by interfering with the cell wall or the membrane of target organisms, either by inhibiting cell wall biosynthesis or causing pore formation, subsequently resulting in death. The incorporation of bacteriocins as a biopreservative ingredient into model food systems has been studied extensively and has been shown to be effective in the control of pathogenic and spoilage microorganisms. However, a more practical and economic option of incorporating bacteriocins into foods can be the direct addition of bacteriocin-producing cultures into food. This paper presents an overview of the potential for using bacteriocin-producing LAB in foods for the improvement of the safety and quality of the final product. It describes the different genera of LAB with potential as biopreservatives, and presents an up-to-date classification system for the bacteriocins they produce. While the problems associated with the use of some bacteriocin-producing cultures in certain foods are elucidated, so also are the situations in which incorporation of the bacteriocin-producer into model food systems have been shown to be very effective.

Bacteria↗
PubMedDate not supplied

Evaluating the quality of after death care.

Nursing care rarely ceases following a patient's death. The project described in this article concerns the quality of nursing care delivered to patients following their death. The author concludes that the quality of care depends in large part on whether staff received training in the care of dying patients.

Humans↗
PubMedDate not supplied

[Surrogate endpoints].

The main endpoint of a phase III trial in oncology must be relevant clinically. In practice, this endpoint is either the disease-free or the overall survival, which requires both long term follow-up and a large number of patients. In phase II trials, it is essential to proceed rapidly, and one therefore uses a surrogate endpoint. Surrogate endpoints are adequate for phase II trials. Their use for phase III trials should be restricted to the rare situations where their validity has been established for the therapeutic and a under study. This surrogate endpoint must be faster to obtain than the clinical endpoint it replaces. Ideally, it should capture all of the treatment effect on the main endpoint, i.e. there should be no effect of the treatment on survival, once the value of the surrogate endpoint is known.

Clinical Trials, Phase II as Topic↗
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Developing applications for lactococcal bacteriocins.

While much of the applied research carried out to date with bacteriocins has concerned nisin, lactococci produce other bacteriocins with economic potential. An example is the two component bacteriocin lacticin 3147, which is active over a wide pH range and has a broad spectrum of activity against gram-positive bacteria. Since the genetic determinants for lacticin 3147 are encoded on a large self-transmissible plasmid, the bacteriocin genes may be conveniently transferred to different lactococcal starters. The resulting food-grade strains can then be used to make a significant impact on the safety and quality of a variety of fermented foods, through the inhibition of undesirable microflora. The bacteriocin is heat stable so it can also be used as an ingredient in a powdered form such as a spray-dried fermentate. Given the observation that lacticin 3147 is effective at physiological pH, there is also considerable potential for biomedical applications. Field trials have demonstrated its efficacy in the prevention of mastitis infections in dairy cows. In contrast to lacticin 3147, the lactococcin bacteriocins A, B and M have a narrow spectrum of activity limited to lactococci. Strains which produce these inhibitors can be exploited in the acceleration of cheese ripening by assisting the premature lysis of starter cultures.

Animals↗
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A comparison of resource utilization in nurse practitioners and physicians.

CONTEXT: Nurse practitioners increasingly provide primary care in a variety of settings. Little is known about how resource utilization for patients assigned to nurse practitioners compares with that for patients assigned to physicians. OBJECTIVE: To compare health care resource utilization for adult patients assigned to a nurse practitioner with that for patients assigned to a resident or attending physician. DESIGN: Prospective, quasi-randomized study. SETTING: Primary care clinic at a Veterans Affairs medical center. PATIENTS: 450 new primary care patients: 150 were assigned to a nurse practitioner, 150 to a resident physician, and 150 to an attending physician. OUTCOME MEASURES: We collected data on laboratory and radiologic testing, specialty care, primary care, emergency or walk-in visits, and hospitalizations over a 1-year period. We also collected information on baseline chronic illnesses, blood pressure, and weight. RESULTS: Resource utilization for patients assigned to a nurse practitioner was higher than that for patients assigned to a resident in 14 of 17 utilization measures (3 were statistically significant) and higher in 10 of 17 measures when compared with patients assigned to an attending physician (3 were statistically significant). None of the utilization measures for patients in the nurse practitioner group was significantly lower than those for either physician group. CONCLUSIONS: In a primary care setting, nurse practitioners may utilize more health care resources than physicians.

Chi-Square Distribution↗
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Residual renal function in a large cohort of peritoneal dialysis patients: change over time, impact on mortality and nutrition.

OBJECTIVE: Residual renal function contributes importantly to total solute clearance in peritoneal dialysis (PD) patients. This study was designed to examine the progression of residual renal function over time and its impact on nutrition and mortality in PD patients in the six New England states (ME, NH, VT, CT, MA, RI) comprising End Stage Renal Disease (ESRD) Network 1. DESIGN: As part of the ESRD Clinical Indicators Project, data on 990 PD patients in Network 1 were abstracted from data supplied by dialysis units in the fourth quarter of 1997. This included demographic information; dose of PD in L/day; weekly renal, dialysis, and total Kt/V urea; weekly renal, dialysis, and total creatinine clearance (CCr); serum albumin level; and mortality and transplantation information. Data collection was repeated in the second and fourth quarters of 1998 and in the second quarter of 1999. PATIENTS: 990 PD patients in Network 1. OUTCOME MEASURES: The change in total and renal solute clearances over time, the relationship between renal clearance and mortality, and the relationship between renal clearance and nutritional status, as represented by serum albumin. RESULTS: Over the 2-year period, mean weekly renal Kt/V urea and weekly renal CCr dropped significantly. To examine the effect of residual renal function on mortality, patients were divided into high and low (above and below the median) weekly renal Kt/V urea and weekly renal CCr groups. Patients above the median levels of both weekly renal Kt/V urea and weekly renal CCr had a significantly decreased risk of dying during the observation period, after controlling for age, gender, serum albumin level, and diabetic status [OR for high vs low renal Kt/V urea 0.54 (CI 0.34 - 0.84), OR for high vs low renal CCr 0.61 (CI 0.40 - 0.94)]. The mean weekly renal Kt/V urea was significantly and directly correlated with the mean serum albumin level by Spearman rank correlation (R = 0.133, p < 0.001), as was the mean weekly renal CCr (R = 0.115, p < 0.001). CONCLUSIONS: Residual renal function is an important contributor to total solute clearance in PD patients. Even at low levels it is linked to decreased mortality and better nutritional status.

Adolescent↗
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The impact of bleeding times on major complication rates after percutaneous real-time ultrasound-guided renal biopsies.

BACKGROUND: Previous studies have shown that bleeding times have positive predictive values of only 5% for perioperative bleeding in unselected populations. Nevertheless, performing bleeding times prior to all renal biopsies is common in nephrology practice. METHODS: We report complications of 112 renal biopsies done at Walter Reed Army Medical Center (WRAMC) from 1996-99 performed without preceding bleeding times. Renal biopsies were done only on normotensive (<140/90) patients who had not recently been taking aspirin or non-steroidal anti-inflammatory agents, under real-time ultrasound guidance with automated 16 g (WRAMC) spring-loaded guns. High-risk patients (with serum creatinine > or = 3 mg/dl or creatinine clearance < or =30 cc/min by Cockroft-Gault formula, N=18, 16%) at WRAMC were treated with pre-renal biopsy estrogens or DDAVP. Factors were tested for their association with complications after renal biopsy using Chi Square testing for categorical variables and student's t-test for continuous variables. A stepwise logistic regression model was used to test for independent significance of factors. RESULTS: There were two cases each of gross hematuria and inadequate tissue (1.8% each). There were no transfusions or deaths. In univariate analysis, male gender and lower serum creatinine level at time of biopsy were significantly associated with increased risk of complications after biopsy. However, these factors were not significant in logistic regression analysis. CONCLUSION: This study suggests that the use of bleeding times does not significantly alter the major complication rates associated with percutaneous real-time ultrasound guided renal biopsy.

Adolescent↗
PubMedDate not supplied

[Mortality from cancer in France. Changes between 1950 and 1989 in the population aged 35-64].

In the French population aged 35-64, cancer mortality increased yearly by 1 percent in males and decreased yearly by 0.6 percent in females between 1950 and 1989. In males, the increase is mostly due to the sites associated with tobacco and alcohol. The important increase of lung cancer is related to the increase in tobacco consumption from 4.7 g per adult per day in 1950 to 6.3 g in 1976. The increase observed in head and neck cancers is related to tobacco and alcohol. In females, the moderate decrease is due to the decrease observed in uterine cervix and stomach cancer mortality, uncompensated by the increase in breast cancer. Contrary to what is observed in the USA, there is no marked increase in lung cancer mortality for women.

Adult↗
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The clinical nurse specialist: developing the case manager role.

Case management improves cost and quality outcomes in patient care. The clinical nurse specialist is a key person to implement this role and to assure that the nursing focus is on quality outcomes as well as cost factors.

Continuity of Patient Care↗