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We propose a method allowing the automatic exploitation of radioimmunoassay results. The standard curve is calculated according to two models; a linear model by Logit-Log transformation of data and another one using Fisher's orthogonal polynomials. The computer programs are written in FORTRAN IV.
CONTEXT: Many studies have documented race and gender differences in health care received by patients. However, few studies have related differences in the quality of interpersonal care to patient and physician race and gender. OBJECTIVE: To describe how the race/ethnicity and gender of patients and physicians are associated with physicians' participatory decision-making (PDM) styles. DESIGN, SETTING, AND PARTICIPANTS: Telephone survey conducted between November 1996 and June 1998 of 1816 adults aged 18 to 65 years (mean age, 41 years) who had recently attended 1 of 32 primary care practices associated with a large mixed-model managed care organization in an urban setting. Sixty-six percent of patients surveyed were female, 43% were white, and 45% were African American. The physician sample (n = 64) was 63% male, with 56% white, and 25% African American. MAIN OUTCOME MEASURE: Patients' ratings of their physicians' PDM style on a 100-point scale. RESULTS: African American patients rated their visits as significantly less participatory than whites in models adjusting for patient age, gender, education, marital status, health status, and length of the patient-physician relationship (mean [SE] PDM score, 58.0 [1.2] vs 60.6 [3.3]; P = .03). Ratings of minority and white physicians did not differ with respect to PDM style (adjusted mean [SE] PDM score for African Americans, 59.2 [1.7] vs whites, 61.7 [3.1]; P = .13). Patients in race-concordant relationships with their physicians rated their visits as significantly more participatory than patients in race-discordant relationships (difference [SE], 2.6 [1.1]; P = .02). Patients of female physicians had more participatory visits (adjusted mean [SE] PDM score for female, 62.4 [1.3] vs male, 59.5 [3.1]; P = .03), but gender concordance between physicians and patients was not significantly related to PDM score (unadjusted mean [SE] PDM score, 76.0 [1.0] for concordant vs 74.5 [0.9] for discordant; P = .12). Patient satisfaction was highly associated with PDM score within all race/ethnicity groups. CONCLUSIONS: Our data suggest that African American patients rate their visits with physicians as less participatory than whites. However, patients seeing physicians of their own race rate their physicians' decision-making styles as more participatory. Improving cross-cultural communication between primary care physicians and patients and providing patients with access to a diverse group of physicians may lead to more patient involvement in care, higher levels of patient satisfaction, and better health outcomes.
A routine is described that readily allows the rescaling of linear histographic data to a corresponding logarithmic histogram. This procedure significantly improves data display, particularly where a wide range in the measured parameter is encountered. The logarithmic scale displays peaks with band widths more proportional to their respective coefficients of variation than is the case in a linear display. Rescaling several linear histograms to a common logarithmic scale allows the combination of these linear data even though the linear ranges are different. This routine is presented as a program written in BASIC for execution on a microcomputer.
To complement results from individual test locations, clinicians also evaluate indices, as they give a succinct overview of the visual field. This, however, requires exact knowledge of their variability. The present study was designed to determine normal interindividual variability of global visual field indices and incorporates a data base of a multicenter study performed with Octopus 201 perimeters using Program G1. The 824 fields thus obtained included 139 fields of 139 healthy volunteers who had undergone two previous visual fields and completed all three phases of program G1. The index mean sensitivity showed a significant and linear decrease with increasing age, 0.064 dB/year of life. The indices loss variance, corrected loss variance, and short-term fluctuation did not correlate significantly with age. Percentiles are given for these visual field indices. While within the limits of normal values provided by the manufacturer for these indices, these results suggest that visual fields with "borderline" values require further clinical investigation in reliable, experienced subjects. The results may help clinicians to better evaluate global visual field indices and, therefore, to detect loss of visual function earlier.
The computer program CASPER for structural analysis has been tested on some oligosaccharides. The program is shown to predict the correct structure of five linear or branched tri- to hexasaccharides using information on components and linkage positions and NMR chemical shifts. Theoligosaccharides are either reducting or methyl glycosides.
An efficient algorithm is described for finding matches, repeats and other word relations, allowing for errors, in large data sets of long molecular sequences. The algorithm entails hashing on fixed-size words in conjunction with the use of a linked list connecting all occurrences of the same word. The average memory and run time requirement both increase almost linearly with the total sequence length. Some results of the program's performance on a database of Escherichia coli DNA sequences are presented.
A non-linear mathematical model for the computerized description of mood curves is presented. This model reaches a high goodness of fit to the real data and seems superior to a linear model recently proposed. Using this model in a computer program for describing the mood data of a large sample of psychiatric inpatients, significant and clinically meaningful group differences between the mood curves of schizophrenic, endogenous depressive, and neurotic depressive inpatients could be demonstrated. The application of this methodology might be helpful among others in the field of evaluative research.
The purpose of this paper was to examine the correlation between the maximum tolerated dose (MTD) and the low-dose estimate of the virtually safe dose (VSD) for animal carcinogens. Chronic bioassay results from the National Cancer Institute/National Toxicology Program carcinogenesis screening program were used. Estimates of the VSD were obtained by linear low-dose extrapolation for which an adequate dose-response relationship existed at the same tumor site in the same sex for both rats and mice. Estimates of the VSD were compared with the MTD for 69 tumor sites from 38 chemicals for rats and mice. The MTDs ranged from high to low toxicity (1 ppb to 4.4% in the diet). The overall geometric mean of the ratio of the MTD to the VSD corresponding to a maximum estimated risk of 10(-6) was 3.8 x 10(5). Of the 138 cases, only 3 cases were more than a factor of 10 from the mean ratio. This suggested that a quick estimate of the VSD could be obtained by dividing the MTD, obtained from a subchronic study, by 400,000. Further, if the human exposure is less than 10(-7) X MTD, the estimated risk is likely to be negligible even if the chemical is a carcinogen. It may not be worthwhile to conduct a chronic bioassay for the purpose of demonstrating a negligible risk, if the chemical is likely to be carcinogenic, unless the human exposure is extremely low.(ABSTRACT TRUNCATED AT 250 WORDS)
Most radiation therapy dose calculation methods require the determination of the effective path length of the primary radiation from the radiation source to the point at which the dose is calculated. This usually involves representing the patient anatomy as a set of polygons (contours) as approximations to plane curves. Several algorithms are known for determining the length of a segment or segments on a ray through a planar contour, that are interior to the contour. We have implemented two of these algorithms in a test program to benchmark their relative efficiency. One algorithm uses a linear search over all the contour segments, and the other method represents the contour as a binary tree of "strips," of successively increasing resolution. In general, the tree search should give times proportional to log(n) where n is the number of contour segments, and the linear search time should be proportional to n. Thus, one might expect the tree search to run faster once the number of segments reaches some sufficiently large value. We found that this value is a number of contour points far in excess of that typical for contours representing radiation therapy patient anatomy. Therefore, for this application the linear search method is more efficient.
PURPOSE: Late G2 and M are the most radiosensitive phases of the cell cycle. Cells exposed to paclitaxel develop a cell cycle arrest in G2/M. These studies were performed to assess the in vitro radiosensitization properties of paclitaxel in human tumor and rodent cell lines. METHODS AND MATERIALS: The effect of paclitaxel on the radiation sensitivity of human breast (MCF-7), lung (A549), ovary (OVG-1) adenocarcinoma and Chinese hamster lung fibroblast V79 cells was determined with clonogenic assays. DNA flow cytometry studies were performed to define the cell cycle characteristics of the cells during irradiation. Survival curve parameters for all cell lines were determined with the use of a computer program which represents cell survival after radiation by a linear-quadratic model. RESULTS: All cell lines developed a G2/M block after exposure to paclitaxel for 24 h. However, the degree of radiosensitization produced by paclitaxel varied among the cell lines. The maximal sensitizer enhancement ratio (SER) of paclitaxel was 1.8 in MCF-7 cells, 1.6 in OVG-1 cells, and 1.7 in V79 cells. However, no concentration of paclitaxel was able to enhance the radiation sensitivity of A549 cells. Paclitaxel increased the linear (alpha) component of the radiation survival curves in all cell lines. The quadratic (beta) component was unaffected by paclitaxel in the rodent cells. High concentrations of paclitaxel (> or = 1000 nM) increased beta slightly in the human cell lines but there was considerable variation in the effect of paclitaxel on beta. The cells which were sensitized to radiation by paclitaxel had a relatively small baseline alpha component, while A549 cells had a large alpha component. CONCLUSION: We conclude that paclitaxel is a modest radiosensitizer in some, but not all, human tumor cells. Paclitaxel appears to cause radiosensitization mainly by increasing the alpha component of radiation survival curves. Cells that normally have a relatively small alpha component should exhibit the most radiosensitization in response to paclitaxel while cells with a large alpha component should show little or no radiosensitization after paclitaxel treatment. Because the greatest effect of paclitaxel is on the linear component of radiation survival curves, these results indicate that paclitaxel may be an effective radiation sensitizer in many human tumors treated at clinically relevant radiation doses of 2 Gy or less.
BACKGROUND: Partial seizure disorder is typically treated by monotherapy with antiepileptic drugs (AEDs). However, when the condition is refractory to the initial treatment regimen, patients may be switched to monotherapy with another AED or to combination therapy with the initial AED plus a second AED. OBJECTIVES: The purpose of this study was to examine the economic costs associated with treatment-refractory partial seizure disorder and to compare the costs of 2 alternative approaches: a switch to oxcarbazepine (OXC) monotherapy or the addition to the regimen of another AED (AED add-on). METHODS: Adult patients with a diagnosis of partial seizure disorder who received initial AED monotherapy between January 1, 2000, and March 31, 2003, were identified from the PharMetrics Patient-Centric Database, a health plan administrative claims database. The medical and pharmacy history of these patients was analyzed from 6 months before a change to either OXC monotherapy or AED add-on therapy through 12 months after the change in treatment. Total health care resource utilization and the associated costs were compared within each cohort before and after the change, as well as between cohorts, with statistical differences tested using Wilcoxon rank sum tests. Multivariate econometric analyses were performed to examine the impact of age, sex, geographic location, Charlson Comorbidity Index, and the presence of specific comorbidities. RESULTS: Demographic and clinical characteristics 102 were similar between the OXC monotherapy cohort (n = 259) and the AED add-on cohort (n = 795). Annual direct treatment costs increased in both groups in the period after the failure of initial monotherapy, increasing from 10,462 US dollars to 11,360 US dollars in the OXC cohort and from 10,137 US dollars to 12,201 US dollars in the AED add on cohort (P < 0.01). Increased pharmacy costs were the primary driver behind cost increases in both cohorts. Patients in the AED add-on cohort were significantly more likely to have an emergency department visit during the period after the failure of initial monotherapy compared with the OXC monotherapy cohort (odds ratio = 1.52; P < 0.05). CONCLUSION: Despite limitations, the results of retrospective analysis of claims data suggest that the care of patients with treatment-refractory partial seizure disorder is costly and may vary significantly based on the pattern of care.
Cryo-electron microscopy of vitreous sections (CEMOVIS) has recently been shown to provide images of biological specimens with unprecedented quality and resolution. Cutting the sections remains however the major difficulty. Here, we examine the parameters influencing the quality of the sections and analyse the resulting artefacts. They are in particular: knife marks, compression, crevasses, and chatter. We propose a model taking into account the interplay between viscous flow and fracture. We confirm that crevasses are formed on only one side of the section, and define conditions by which they can be avoided. Chatter is an effect of irregular compression due to friction of the section of the knife edge and conditions to prevent this are also explored. In absence of crevasses and chatter, the bulk of the section is compressed approximately homogeneously. Within this approximation, it is possible to correct for compression by a simple linear transformation for the bulk of the section. A research program is proposed to test and refine our understanding of the sectioning process.
BACKGROUND: This study reports the effect of providing Norwegian school children with free fruit or vegetables every school day and the effect of an existing fee-based School Fruit Programme. METHODS: Seventh grade pupils and their parents completed questionnaires at baseline (autumn 2001) and at follow-up (spring 2002). Nine schools participated in the School Fruit Programme for free (Free fruit), nine schools took part at standard conditions (Paid fruit), and 20 schools did not take part in the subscription programme (No fruit). A total of 795 7th graders (11 or 12 years old at baseline) participated both at baseline and at follow-up. RESULTS: At follow-up, pupils attending the Free fruit schools had significantly higher intake of fruit and vegetables at school than the pupils at the Paid fruit and No fruit schools (P < 0.001, mean intakes were 1.1, 0.4 and 0.2 portions, respectively). Subscribers at the Paid fruit schools had significantly higher intake than the non-subscribers at the same schools. CONCLUSIONS: Providing a free piece of fruit or a vegetable is an effective strategy to increase school children's fruit and vegetable intake. The existing School Fruit Programme appears to increase the intake among the subscribers, but thereby also tends to increase an existing difference in consumption patterns among subscribers and non-subscribers.
Curve regeneration is applied to the continuous-flow determination of serum Na +, K +, Cl- and CO2 by the Flame photometer IV (Technicon Corp.). A Hewlett-Packard 2100 A mini-computer is used for data acquisition. The continuous-flow parameters of both rise and fall curves are estimated from computer sampled voltage outputs over the standard profile. An additional interaction correction variable designated as Beta (beta) is described and applied to the regenerated peaks of the cresol red CO2 procedure. The phenolphthlalein CO2 methodology, showing improved flow parameters over those for the cresol red procedure is adapted for the Flame IV system. The basic program design is briefly outlined. Typical computer determined calibration curves (linear regression) and sample peak tracings for both the basic and regenerated techniques are illustrated.
Three lakes in Snowdonia and two on the island of Anglesey were surveyed using a Compact Airborne Spectrographic Imager (casi). Water samples for chlorophyll measurements and phytoplankton counts were collected at the time of the overflight and the optical characteristics of the lakes recorded by a scanning spectroradiometer. Spectral measurements in the five lakes showed that their optical characteristics were primarily determined by the concentration of phytoplankton in suspension. All the lakes were relatively clear, but the more productive waters contained small amounts of dissolved organic carbon of autochthonous origin. The airborne imaging spectrometer was programmed to measure upwelling radiance in eight narrow bands and linear regressions used to compare the performance of a selected range of chlorophyll retrieval algorithms. The results showed that the most effective algorithms were those based on measurements in the blue and green portions of the spectrum. The best single band algorithm was centred on 440 nm and explained 75% of the measured variation in the concentration of chlorophyll. The best multi-band algorithm was based on measurements taken at 560 and 440 nm and accounted for 94% of the recorded variation. Chlorophyll maps produced by this algorithm showed that the phytoplankton in most of the lakes was homogeneously distributed but surface patches of cyanobacteria were detected at one location.
OBJECTIVE: To investigate the effect of performance-based financial incentives on the influenza immunization rate in primary care physicians' offices. DESIGN: Randomized controlled trial during the 1991 influenza immunization season. SETTING: Rochester, New York, and surrounding Monroe County during the Medicare Influenza Vaccine Demonstration Project. PARTICIPANTS: A total of 54 solo or group practices that had participated in the 1990 Medicare Demonstration Project. INTERVENTIONS: All physicians in participating practices agreed to enumerate their ambulatory patients aged 65 or older who had been seen during the 1990 or 1991 calendar years, and to track the immunization rate on a weekly basis using a specially designed poster from September 1991 to January 1, 1992. Additionally, physicians agreed to be randomized, by practice group, to the control group or to the incentive group, which could receive an additional $.80 per shot or $1.60 per shot if an immunization rate of 70% or 85%, respectively, was attained. MEASUREMENTS: The main outcome measures are the 1991 immunization rate and the improvement in immunization rate from the 1990 to 1991 influenza seasons for each group practice. RESULTS: For practices in the incentive group, the mean immunization rate was 68.6% (SD 16.6%) compared with 62.7% (SD 18.0%) in the control group practices (P = .22). The median practice-specific improvement in immunization rate was +10.3% in the incentive group compared with +3.5% in the control group (P = .03). CONCLUSIONS: Despite high background immunization rates, this modest financial incentive was responsible for approximately 7% increase in immunization rate among the ambulatory elderly.
A new, simple device generates accurate nano- and microflow rate gradients from any conventional HPLC system. The core of the new device is represented by an electric-actuated, computer-controlled, multiposition HPLC valve. The valve hosts six reservoirs for as many different mobile-phase compositions of increasing strength. A low flow rate stream pushes the weakest solvent through the column as long as required and at the desired flow rate, until the chromatographic run is started. From this time on, the electric actuation allows one to select which reservoir will be on-line with the column and for how long, thus generating a specific solvent gradient, through a sequence of controlled segments of precise mobile-phase composition. This permits one not only to exactly reproduce the programmed slope but also to achieve different gradient shapes (i.e., linear, convex, concave) for different separation needs. The new device has proven to be reliable and reproducible even at the lowest flow rate tested (250 nL x min(-1)) and in different chromatographic conditions.
A method for the analysis of hydroxyurea (HU) in solutions, powder, or capsules by use of capillary gas chromatography with N-P thermionic specific detection is described. Upon injection of an HU solution in a methanol and acetone mixture, the drug formed pyridine which was well separated from the internal standard (thiotepa) on a 30-m fused-silica, SE-30 capillary column with temperature programming. The peak height ratio versus concentration standard curves were linear with correlation coefficient ranging between 0.9942 and 0.9993. The coefficients of variation at 5, 25, and 50 micrograms/L were 7.2, 5.7, and 5.5%, respectively. Hydroxyurea was extracted from powder or capsule formulations with a mixture of methanol and acetone (50:50, v:v), and the percentage found of the label claim for 10 capsules ranged between 96.7 and 104.9 (mean = 100.1; CV = 2.7%). Further, this assay was used to examine the stability of hydroxyurea in aqueous solutions at 4, 23, and 45 degrees C, and the apparent first-order rate constants observed at these temperatures were 0.06407, 0.08113, and 0.1293 day-1, respectively; the activation energy was 3011 cal.K-1.mol-1.