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J Weeks

Publications and source records attributed to J Weeks.

At least 19 recordsLinked to original sources
PubMed2004

Measurement of the phase diagram of DNA unzipping in the temperature-force plane.

We separate double stranded lambda phage DNA by applying a fixed force at a constant temperature ranging from 15 to 50 degrees C, and measure the minimum force required to separate the two strands. The measurements also offer information on the free energy of double stranded DNA (dsDNA) at temperatures where dsDNA does not thermally denature in the absence of force. While parts of the phase diagram can be explained using existing models and free energy parameters, others deviate significantly. Possible reasons for the deviations between theory and experiment are considered.

Biophysics↗
PubMed2004

Factors influencing treatment recommendations in early-stage Hodgkin's disease: a survey of physicians.

BACKGROUND: The aim of this study was to explore variation in practice patterns and identify factors associated with physicians' treatment decisions for early-stage Hodgkin's disease. METHODS: We conducted a one-time mail survey of oncologists randomly selected from directories of national oncology societies (n = 207) and Hodgkin's disease experts (n = 147). The survey included questions on (i) physician factors, (ii) preferred treatment choices for six case scenarios of early-stage Hodgkin's disease that varied by patient factors, and (iii) thresholds for changing treatment recommendations. RESULTS: The response rate was 50%. For non-bulky Hodgkin's disease, 69% of respondents chose combined modality therapy (CMT). On multivariate analysis, physician factors that independently predicted for choice of CMT included a high Hodgkin's disease case load (P = 0.02) and a high percentage of patients enrolled in clinical trials (P = 0.05). Radiation oncologists had a lower threshold for adding radiation therapy (P = 0.02). More experience with second malignancy cases and longer time in practice were associated with a higher threshold for adding radiation therapy (P = 0.04 and P = 0.008, respectively). In stratified analyses, treatment decisions of non-experts were significantly influenced by physician factors, but not by patient factors. Conversely, choices of Hodgkin's disease experts were insensitive to all physician factors, but experts were significantly more likely to select chemotherapy alone in young women and CMT in older patients. CONCLUSIONS: Our results indicate that physician factors including practice type and experience may in part explain variation in practice pattern for Hodgkin's disease therapy. Hodgkin's disease experts are more likely to tailor therapy according to individual patient factors.

Adult↗
PubMed2001

The surgical management of women with ovarian cancer in the south west of England.

The surgical management of epithelial ovarian cancer in the South West of England was studied in the two years 1997-1998 in order to determine the factors that influence the outcome of surgery and to provide a baseline from which to assess the effect of centralisation of cancer services. All hospitals in the South West region of England participating in the Regional Cancer Organisation's longitudinal study of outcomes in gynaecological malignancies are included. Six hundred and eighty-two patients with epithelial ovarian cancer were registered with the RCO in the two-year study period. Five hundred and ninety-five women were offered primary cytoreductive surgery of which 438 were said to be optimally cytoreduced. Applying multivariate models to analyse the outcome of surgery, older patients (OR = 0.82 per 5-year increase in age, P = 0.0003), patients treated in hospitals managing fewer than ten cases of ovarian cancer per year (OR = 1.92, P = 0.02) and patients with FIGO stage 3 (OR = 0.02, P < 0.0001) or 4 (OR = 0.002, P < 0.0001) disease were less likely to be optimally cytoreduced. Gynaecological oncologists were 2.06 times more likely to attain optimal cytoreduction when compared to general gynaecologists and this was statistically significant (P = 0.01). The results from this study support the argument that limiting surgery for ovarian malignancy to specialised surgeons improves the extent of cytoreductive surgery.

Adult↗
PubMed2001

A prospective regional audit of surgical management of endometrial cancer in the South and West of England.

The results of a prospective audit of surgical management of endometrial cancer in the South and West of England is presented. A minimum data set was defined and information collected prospectively. There was limited tertiary referral to a gynaecological oncologist. The role of centralisation of endometrial cancer care has been questioned, as surgery has traditionally been simple in patients perceived to be at increased risk of more radical surgery. However, this audit demonstrates that standards of even this simple care within the region are often inadequate, with only one-third of patients having basic staging procedures performed fully. This has important implications for patients management, future interpretation of outcome data and clinical governance in endometrial cancer care.

Journal Article↗
PubMed2000

A randomized controlled trial of the effect of increased intravenous hydration on the course of labor in nulliparous women.

OBJECTIVE: One variable that has the potential to affect the course of labor but has not been evaluated previously is the adequacy of maternal hydration. Typical orders provide for 125 mL of intravenous fluids per hour in patients taking limited oral fluids. Many such patients are clinically dehydrated. Physiologists have shown that increased fluids improve skeletal muscle performance in prolonged exercise. This study was designed to determine whether increased intravenous fluids affect the progress of labor. STUDY DESIGN: Nulliparous women with uncomplicated singleton gestations at term, in spontaneous active labor with dilatation between 2 and 5 cm, and with a cephalic presentation were included. Patients who gave consent were randomly selected to receive either 125 mL or 250 mL of intravenous fluids per hour. RESULTS: One hundred ninety-five patients were randomly selected, 94 to the 125-mL group and 101 to the 250-mL group. Prerandomization variables were well matched between the 2 groups. The mean volume of total intravenous fluids was significantly greater in the 250-mL group (2008 mL vs 2487 mL; P =.002), as was the mean hourly rate (152 mL/h in the 125-mL group vs 254 mL/h in the 250-mL group; P =.001). The frequency of labor lasting >12 hours was statistically higher in the 125-mL group (20/78 [26%] vs 12/91 [13%]; P =.047). In addition, there was a trend favoring longer mean duration of the first stage and total duration of labor in patients delivered vaginally in the 125-mL group, by 70 and 68 minutes, respectively (P =.06). There was a trend toward a lower frequency of oxytocin administration for inadequate labor progress in the higher fluid rate group (61 [65%] in the 125-mL group vs 51 [49%] in the 250-mL group; P =.06). Cesarean deliveries were more frequent in the 125-mL group (n = 16) than in the 250-mL group (n = 10) but did not reach statistical significance. CONCLUSION: This study presents the novel finding that increasing fluid administration for nulliparous women in labor above rates commonly used is associated with a lower frequency of prolonged labor and possibly less need for oxytocin. Thus inadequate hydration in labor may be a factor contributing to dysfunctional labor and possibly cesarean delivery. Consideration of this factor in clinical management and in future studies considering variables that affect labor is warranted.

Adult↗
PubMed1999

Do mite avoidance measures affect mite and cat airborne allergens?

BACKGROUND: Effective mite allergen avoidance measures are presumed to reduce airborne allergens yet the quantity in the air is rarely measured. OBJECTIVE: To monitor airborne allergen during a placebo-controlled mite allergen avoidance study. METHODS: Bedrooms of 56 atopic asthmatic children were randomly allocated to hot washing and encasing covers + acaricide (active regime) or placebo treatment. Dust was collected from the mattress, bedding and carpets; airborne allergen was measured using Casella samplers and dust settling in open Petri dishes. Der p 1, Der p 2 and Fel d 1 were measured. RESULTS: After 24 weeks of mite allergen avoidance the Casella air-samplers collected Der p 1 less frequently in active than placebo-treated bedrooms (0 vs. 29%, P<0.05) and Petri dishes in the active group collected less than baseline (0.2 vs. 0.6 ng/day P<0.05). Homes without cats had less cat allergen than cat-owning homes and when actively treated for 24 weeks showed a greater reduction (P = 0.03) in mattress cat allergen than the placebo group. CONCLUSION: Encasing covers and hot washing of bed linen reduced mite aeroallergen (and mattress cat allergen in the absence of cats). This could mean dual benefits to a patient sensitive to both mite and cat.

Air Pollutants↗
PubMed1999

Fatal and non-fatal injuries from vessels under air pressure in construction.

Using a surveillance system that captures data on construction workers treated in an urban emergency department, we identified a series of injuries caused by vessels and tools under air pressure. We describe those six cases, as well as similar cases found in the Census of Fatal Occupational Injuries; we also review data from the National Surveillance for Traumatic Occupational Fatalities database and data from the Bureau of Labor Statistics. Among the injuries and deaths for which we had good case descriptions, the majority would have been prevented by adherence to existing Occupational Safety and Health Administration standards in the construction industry.

Accidents, Occupational↗
PubMed1999

Outcomes assessment in the NCCN: 1998 update. National Comprehensive Cancer Network.

The assessment of outcomes is a major priority of the National Comprehensive Cancer Network (NCCN). To date, the NCCN's outcomes program has (1) made a systematic inventory of member institutions' existing data sources; (2) begun a collaborative project with the National Cancer Data Bank to compare specific surgical patterns of care in NCCN institutions with national norms; and (3) begun the creation of a prospective outcomes database within the NCCN. As the first step in the database initiative, five NCCN institutions participated in a pilot project in one disease, breast cancer, aimed at developing and testing techniques of data collection, aggregation, and analysis. Six more sites were added to the pilot program in 1998. As of September 1998, data on over 1,000 unique cases had been submitted to the database, with the number of additional cases expected to triple or quadruple within the ensuing 12 months. Future plans call for (1) further expansion of the breast cancer database, both in terms of the number of institutions participating and the scope of data being collected; (2) the addition of a second disease, non-Hodgkin's lymphoma, to the database; and (3) the establishment of partnerships with other organizations for whom the database might provide useful information, such as insurers, pharmaceutical and biotechnology firms, and regulatory and accrediting bodies.

Breast Neoplasms↗
PubMed1999

Costs and cost-effectiveness of colorectal cancer prevention and therapy.

For cancer, the evaluation of new prevention and therapeutic strategies has traditionally focused almost exclusively on safety and efficacy. However, comparison of the costs and cost-effectiveness of medical interventions is increasingly being recognized as an important goal. Cancer care is a prime target for scrutiny because US cancer treatment consumes over $40 billion per year or approximately 12% of total health care expenditures. Colorectal cancer (CRC) treatment costs over $6.5 billion per year and, among malignancies, is second only to breast cancer at $6.6 billion per year. Nonetheless, there are relatively few published studies addressing the economic consequences of CRC. This review describes the strengths and limitations of the major types of health economic analyses, as well as the existing literature on the costs and cost-effectiveness of CRC prevention and treatment. Although standard approaches to both CRC screening and treatment appear cost-effective when compared with no intervention, the relative cost-effectiveness of different screening, treatment, and posttherapeutic surveillance strategies remains uncertain. As databases and information systems able to integrate comprehensive cost and treatment data grow in availability and sophistication, it should become easier to compare the impact of various approaches in terms of both traditional and economic outcomes. Over the next few years, the results of the first clinical trials that prospectively assess economic end points in CRC are anticipated; the experience resulting from these efforts should stimulate and enhance future studies.

Colorectal Neoplasms↗
PubMed1998

V antigen of Yersinia pestis inhibits neutrophil chemotaxis.

V antigen (V), a secreted protein encoded by the 70 kb low-calcium response plasmid of Yersinia pestis, is an essential virulence factor. In animal models, it inhibits the early host inflammatory response to infection which is associated with decreased blood and tissue levels of proinflammatory cytokine synthesis. To elucidate further the pathogenetic mechanism(s) of V, in vitrosystems are needed to measure and analyse relevant functional activities of V. We studied the effect of V on the migration of neutrophils to a chemoattractant both in vivo and in vitro. Peripheral injection of V was associated with a reduction in the number of PMN migrating into s.c. sponges and i.p. exudates. Similarly, pre-incubating human peripheral blood neutrophils with >/=ng/ml V significantly inhibited the in vitro chemotactic response to the peptide chemoattractant FMLP. The inhibitory activity of V was inactivated by heat and was neutralized by rabbit polyclonal anti-V IgG as well as by sera from mice surviving infection with Y. pestis. Recombinant polyhistidine-tagged V fusion proteins retained biological activity compared to V proteins lacking the tag. Inhibition of chemotaxis appears to be the first demonstration of an in vitro biological effect of V and may be a useful model to elucidate its molecular mechanism of action.

Animals↗
PubMed1998

Recurrence of gestational diabetes: who is at risk?

OBJECTIVE: The object was to determine the recurrence rate of gestational diabetes mellitus and to find various risk factors that might increase this rate. STUDY DESIGN: Seventy-eight patients with gestational diabetes mellitus in their index pregnancies were evaluated in subsequent pregnancies. Medical records for the index and subsequent pregnancies were abstracted for age, parity, body mass index, birth weight, gestational age of gestational diabetes mellitus diagnosis, insulin requirement, weight gain, and interval between pregnancies. These variables were then compared between patients with and without gestational diabetes mellitus in their subsequent pregnancies. RESULTS: Fifty-four of 78 patients (69%) had gestational diabetes mellitus in a subsequent pregnancy. The recurrence of gestational diabetes mellitus was more common when the following variables were present in the index pregnancy: parity > or = 1 (P < .004; odds ratio 3.0, 95% confidence interval 1.4-4.8), body mass index > or = 30 kg/m2 (P < .04; odds ratio 3.6, 95% confidence interval 1.1-25.9), gestational diabetes mellitus diagnosis at < or = 24 gestational weeks (P < .0003; odds ratio 20.4, 95% confidence interval 2.5-444), and insulin requirement (P < .0002; odds ratio 2.3, 95% confidence interval 1.3-3.4). A weight gain of > or = 15 pounds (P < .003; odds ratio 2.9, 95% confidence interval 1.0-5.3) and an interval between pregnancies < or = 24 months (P < .03; odds ratio 1.6, 95% confidence interval 1.1-2.2) were also associated with a recurrence of gestational diabetes mellitus. A multiple logistic regression analysis revealed that an interval of < or = 24 months and a weight gain of > or = 15 pounds between pregnancies were most strongly correlated with a recurrence of gestational diabetes mellitus. CONCLUSIONS: Gestational diabetes mellitus is more likely to recur in parous, obese women who had an early gestational diabetes mellitus diagnosis and required insulin in the index pregnancy. In addition, a shorter interval (< or = 24 months) and a larger weight gain (> or = 15 pounds) between pregnancies appear to be the most significant risk factors for a recurrence of gestational diabetes mellitus.

Age Factors↗
PubMed1998

Assessing the value of a new pharmaceutical. A feasibility study of contingent valuation in managed care.

OBJECTIVES: The authors assessed the feasibility and construct validity of the contingent valuation method for measuring the monetary value to healthy enrollees in a health maintenance organization of a new drug, filgrastim, as prophylaxis against febrile neutropenia after chemotherapy treatment for cancer. METHODS: A random sample of 220 enrollees from a closed-panel staff-model health maintenance organization who did not have cancer were interviewed. Chemotherapy, febrile neutropenia and filgrastim were described by video and decision board. Questions were asked in two different scenarios: (1) User-based: Assuming they were at the point of consumption and about to receive chemotherapy, what is the maximum they would be willing to pay to receive filgrastim? and (2) Insurance-based: Given they were at risk of cancer in the future, what is the maximum they would be willing to pay in additional monthly insurance premiums to add filgrastim to the plan? In a second insurance scenario where respondents were told that filgrastim was covered, what is the minimum reduction in premium that persons were willing to accept to relinquish coverage of the drug? A 2 x 2 factorial design was used to contrast two bidding algorithms to test for starting point bias and two 5-yearly prior risks of cancer, 1/200 versus 1/100. Main effects were tested by ANCOVA controlling for age, sex, health, and income. RESULTS: Demographics of experimental cells were similar. No evidence was found of significant starting point bias. For user-based questions, as expected, willingness-to-pay increases with febrile neutropenia risk reduction, but at a declining marginal rate. Despite careful presentation of information to respondents, willingness-to-pay for insurance was higher in the lower prior risk group. Consistent with previous contingent valuation studies, the authors of the present study found evidence that willingness-to-accept exceeds willingness-to-pay for coverage of the same benefit. CONCLUSIONS: An insurance-based contingent valuation study is feasible in a health maintenance organization. Construct validation evidence was encouraging, with the exception of the test for prior risk of cancer; however, this was a between-person contrast and may have been confounded by other factors.

Adult↗
PubMed1998

Overview of outcomes research and management and its role in oncology practice.

Outcomes assessment describes a variety of activities, including classic clinical trials with quality of life and cost end points, observational studies examining the outcomes of treatment in the course of routine clinical care, and the process of managing patterns of care in clinical practice. These activities share important common features, including an emphasis on quality of life and economic outcomes, an explicit consideration of the importance of patient characteristics in determining outcomes, and a broad definition of what constitutes cancer care. The primary uses of outcomes data are to evaluate treatments and to assess the quality of care provided by physicians, health care institutions, and health insurance plans. Outcomes management integrates these activities through the implementation of guidelines, ideally based on empiric data on the relationship between medical interventions and outcomes; and the measurement of performance against a set of quality indicators derived from those guidelines. One of the biggest challenges facing clinicians today is how to reconcile the need to do what is best for patients with the need to practice cost-conscious medicine. High-quality outcomes data are at the heart of the solution. This presentation is a brief overview of outcomes research and management and its role in oncology practice.

Decision Making↗
PubMed1996

Economic analyses in health care: an introduction to the methodology with an emphasis on radiation therapy.

Payers are increasingly interested in knowing whether they are receiving value for the dollars they spend on health care. Because economic analysis will be used as a means of evaluating radiation therapy, it is important that radiation oncologists understand the basic methodology employed in such analyses. This review article describes the four basic types of economic analyses: cost minimization, cost effectiveness, cost utility, and cost benefit. Specification of alternative therapies, choice of perspective of the analysis, measurements of costs and benefits, and the role of discounting and sensitivity analyses are discussed. Published economic analyses that pertain directly to treatment with radiation therapy are reviewed. Finally, we close with a brief discussion of the potential areas for future economic outcomes research in radiation oncology.

Cost-Benefit Analysis↗