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The purpose of this study was to assess the validity of the data supported by MKG by testing the accuracy of both the raw data and corrected data of it by means of precise measurements throughout the entire range of functional mandibular movements. This paper also presents a computer processing which can correct the geometric divergence and has the same effect of MKG analyzer.
A technique for acquiring dynamic geometric mean studies utilizing a single-headed rotating gamma camera has been developed. The camera head is repeatedly rotated between opposed views under computer control. A single data set results, from which a dynamic sequence of geometric mean images can be produced. Software has been developed to accomplish data acquisition and the reformatting required. The accuracy of the geometric mean data formed using this technique has been studied experimentally, and compared with results obtained from anterior and posterior sequences. In a simple clearance experiment of a 1-I volume with a known clearance of 20 ml.min-1, the geometric mean data resulted in estimates of volume remaining in the container with a mean error or +2.0 ml (s.d. = 5.7 ml, range -4.5 +/- 15.3 ml), while the anterior and posterior images yielded volume estimates with mean errors of -10.1 ml (s.d. = 16.6 ml, range -47.4 +/- 10.5 ml) and +35.5 ml (s.d. = 22.6 ml, range -3.2 +/- 51.6, ml), respectively. The technique is easy to implement and does not require modification of existing hardware. An application of the technique to a clinical study of gastric emptying is also included.
The objective of this investigation was to establish and validate an HPLC method with UV detection for the determination of paroxetine in human plasma. The method was validated in the concentration range from 6 to 100 ng ml-1. The lower limit of reliable quantification (LLQ) was 6 ng ml-1. The extraction efficiency varied from 67.1 to 85.5% over this range. Accuracies calculated at three concentrations in each of three separate runs were between 99.4 and 109.6%, and precision data were between 1.86 and 9.1%. The means of the between-day precision at all concentrations were between 2.77 and 7.32%. The corresponding means of the accuracy data were in the region of 102.4 to 106.3%.
We estimated KOW values that are usually derived by liquid chromatography solely from gas chromatographic (GC) data by selective correlation with PCB congeners as secondary standards. The GC method was established and validated with literature-known values obtained with other methods. Twenty-seven chlorinated diphenyl ethers (PCDE), 19 chlorinated naphthalenes (PCN), 4,4'-DDE, and three brominated diphenyl ethers (PBDE) were used for method validation. The advantages of our method are that only amounts in the nanogram range or less are needed, complex mixtures can be analyzed, KOW values of isomers can be determined, and even the exact structure of compounds does not have to be known. The quality of the KOW values obtained by the GC method mainly depends on the accuracy of the data of the compounds used as standards for the correlation. These data should be based on reliable experimental methods. Our semi-experimental approach in approximating physicochemical data relevant to the environmental distribution--vapor pressure of subcooled liquid and log KOW--can be extended to further classes of compounds because normalized GC retention data are easily available. We exemplified our approach with a bioaccumulating naturally occurring heptachlorinated 1-methyl-1',2-bipyrrole, which is highly abundant in fish from the South Atlantic among others.
Normalization of the data of cDNA microarray is an obligatory step during microarray experiments due to the relatively frequent non-specific errors. Generally, normalization of microarray data is based on the null hypothesis and variance model. In the Yang's model (Yang et al., 2001), at least two types of noises are included. The one is additive noise and the other is multiplicative noise. Usually, background is considered as one of additive noise to the signal and the variation between the signal pixels is the representative multiplicative noise. In this study, the relation between the signal (spot intensity minus background intensity) and background was observed and the influence of background on normalization as a representative additive factor was investigated. Although the relation has not been considered as a factor affecting the normalization, it could improve the accuracy of microarray data when the normalization was carried out considering signal/background ratio. The background dependent normalization decreased the number of genes whose expression levels were changed significantly and it could make their distribution more consistent through the whole range of signal intensities. In this study, printing pin dependent normalization was also carried out regarding the printing pin as a representative multiplicative noise. It improved the distribution of spots in the Cy3-Cy5 scatter plot, but its effect was slight. These studies suggest that there are some influences of the signals on the local backgrounds and they must be considered for the normalization of cDNA microarray data.
Infancy is the period of most rapid postnatal growth and is accompanied by major changes in body composition (BC). There are many challenges to successfully measuring BC of infants in vivo, which include the inherent limitations in the underlying assumptions for each technique. The small body mass and rapid nonuniform changes in body parts, that is, the components of BC during infancy, can strain the technical limits of all methods. Many techniques for in vivo BC measurement used in older people have been applied to infants. However, the vast majority of them either are difficult to adapt for widespread use in infants, or the roles and limitations for using them during infancy are ill-defined because of limited or no critical validation and cross-calibration studies. Based on validation data from animals, well-defined methodological issues in data acquisition and analyses, availability of normative data, and pertinent accuracy and precision of the technique to allow us to determinate clinically relevant changes in BC within a reasonable time interval, three techniques appear to be most suitable for in vivo BC measurement in infants. Anthropometric measurements can be used in field studies or for group comparisons, and total body electrical conductivity (TOBEC) and selected dual-energy X-ray absorptiometry (DXA) measurements can be used to compare BC in individual infants. DXA has the advantages of being able to measure bone mass and the potential to be adaptable to the widely available existing instruments. However, regardless of the techniques used in measuring BC in infants, meticulous attention to details in data acquisition and data analysis, and a knowledge of the limitations of the particular technique are the prerequisites for generating valid data.
BACKGROUND: Evaluating the quality and performance of Primary Health Care (PHC) systems depend on the information system's capacity to generate reliable and accurate information, within social, cultural, and economic context. This paper reports an assessment of a PHC health management information system from PHC Managers'perspectives, METHODS: An adapted 3-part Donabedian model informed our assessment of the structure, process and outcomes of the PHC health information system. Pre-tested, semi-structured questionnaires were administered to the PHC Coordinator, 6 Deputy Coordinators, and 18 officers responsible for the health facilities in Bama Local Government Area of Borno State. RESULTS: Majority of the respondents (n=11) believed that staffing at PHC level was inadequate. Only 5 (27.8%) of the managers had training specific to completing HMIS forms. All the facilities were reported to possess registers for the study year (1993), but their numbers dropped by half consecutively down the preceding years to 1990. None reported a health facility that had a copy of the requisite M&E manual guide to HIMIS. Nonetheless 14 reported that report submissions were timely; chief factors causing delays were lack of transport (35.5%), bad roads (16.1%), and scarcity of forms (9.7%). Twelve (12) of the managers judged that the data collected were always or sometimes accurate. Though only 5 crosschecked data to verify accuracy of the submissions. Eight (8) were of the opinion that computerisation was not necessary for rural PHC information system, and eleven (11) felt that the Bama PHC was not ready for computerisation. Twelve (12) of them felt that the quality of the PHC information system had improved since its devolution to the LGA, however, the main suggestions offered to improve the MIS in general were personnel training (32%), feedback from higher levels (20%), and availability of transportation (16%). CONCLUSION: The information system is only as good as the organisation it serves. Results of this study show majorgaps in the structure of the HMIS at the PHC level which is responsible for gathering data onward to the federal level that culminates in epidemiological and health information for the country. Emphasis for intervention for strengthening information systems should be on starting with generating information for local use, and building local capacity to utilise derived information for daily PHC planning, decision-making and management before the prospect of collecting data for upward submission to higher levels.
The amikacin antimicrobial susceptibility tests were reviewed and found to be acceptable for clinical laboratory use. The early change from the 10-micrograms to the 30-micrograms diagnostic disk concentrations has resulted in reasonable accuracy, according to data from surveys of the College of American Pathologists, and acceptable discrimination between susceptible and resistant microorganisms. Similarly, standardized dilution susceptibility methods have proven acceptable, but great care must be exercised to select an agar medium in which performance was evaluated by the criteria of the National Committee for Clinical Laboratory Standards. Breakpoint concentrations selected as susceptible for amikacin (equal to or less than 16 micrograms/ml) were based on infected patient pharmacokinetics and previously correlated with patient bacteriologic outcome. Amikacin serum levels have been accurately measured by numerous procedures, including gas-liquid chromatography, radioimmunoassay, radioenzymatic assay, bioassay, and latex agglutination tests. Recent surveys of the College of American Pathologists support the earlier suspicions of lower accuracy and specificity with the bioassay method. Care must be taken to rapidly and appropriately process specimens from patients receiving concurrent high doses of antipseudomonal penicillins because of documented inactivation of some aminoglycosides by these penicillins. Amikacin is less affected by these beta-lactams. Evaluations of the antibacterial activity of amikacin in combination with other antimicrobial agents, principally the beta-lactams, continue to show high rates of enhanced killing or synergy. Although the methods for assessment of synergy have not been standardized, remarkably favorable and similar results between laboratories have been reported.
Previous estimates of the age-specific risks of varicella-associated encephalitis and death (the only two varicella complications for which national data are available) have been based on age data for varicella cases from only three reporting areas. In an attempt to estimate more accurately the age-specific risks, 1978, age data for varicella cases were solicited from state epidemiologists. These age-specific data were compared to those from the three original reporting areas and from the National Center for Health Statistics Health Interview Survey (HIS) for the time period 1972 to 1978. The age distribution of state and HIS cases was then compared with that of encephalitis cases and deaths reported between 1972 and 1978 to the Centers for Disease Control and the National Center for Health Statistics, respectively. Despite differences in the number and distribution of varicella cases, both sources clearly identified those greater than or equal to 20 years of age as having the greatest risk of varicella encephalitis or death. Young children also were at increased risk. A number of problems with the reliability and accuracy of the data indicate that more specific data are needed to delineate further the groups most at risk of varicella complications who might benefit most from vaccination, and to evaluate accurately the effects the vaccine might have.
Surprisingly little is known about the mechanisms that underlie variation in female fertility in humans. Data on this topic are nonetheless vital to a number of pragmatic and theoretical enterprises, including population planning, infertility treatment and prevention, and evolutionary ecology. Here we study female fertility by focusing on one component of the interbirth interval: the waiting time to conception during menstrual cycling. Our study population is a Dogon village of 460 people in Mali, West Africa. This population is pronatalist and noncontracepting. In accordance with animist beliefs, the women spend five nights sleeping at a menstrual hut during menses. By censusing the women present at the menstrual huts in the study village on each of 736 consecutive nights, we were able to monitor women's conception waits prospectively. Hormonal profiles confirm the accuracy of the data on conception waits obtained from the menstrual hut census (Strassmann [1996], Behavioral Ecology 7:304-315). Using survival analysis, we identified significant predictors of the waiting time to conception: wife's age (years), husband's age (< 35, 35-49, > 49 years), marital duration (years), gravidity (number of prior pregnancies), and breast-feeding status. Additional variables were not significant, including duration of postpartum amenorrhea, sex of the last child, nutritional status, economic status, polygyny, and marital status (fiancée vs. married). We fit both continuous and discrete time survival models, but the former appeared to be a better choice for these data.
OBJECTIVE: Data on the accuracy of transthoracic echocardiographic (TTE) analysis of coronary flow reserve are scarce. We compared coronary flow reserve measurements assessed using TTE with those achieved using the gold standard of intracoronary Doppler. METHODS: Twenty-one patients admitted for elective coronary angioplasty to the circumflex or left anterior descending (LAD) coronary artery underwent TTE immediately before angioplasty, both at rest and during intravenous administration of adenosine 140 microg/kg/min. Transthoracic images of distal LAD coronary diameter and coronary flow were obtained in 14 patients (66%). These patients then underwent intracoronary Doppler analysis of coronary flow reserve in the distal LAD coronary artery. In 1 patient with a proximal LAD artery lesion, the narrowing could not be crossed with the Doppler guidewire. Paired data on coronary flow reserve were therefore available in 13 patients. RESULTS: Patients were aged 61.7 +/- 8.3 years. Ten were men. Body mass index was 26.3 +/- 4.6 kg/m(2). Resting distal LAD artery blood flow was 18.4 +/- 9.0 mL/min assessed by TTE versus 17.6 +/- 8.1 mL/min by intracoronary Doppler. Hyperemic flow was 36.3 +/- 23.4 versus 33.1 +/- 19.2 mL/min, respectively. Coronary flow reserve was therefore 1.89 +/- 0.66 by TTE compared with 1.83 +/- 0.62 by intracoronary Doppler. Limits of agreement for coronary flow reserve were -0.28 to +0.44, well within boundaries of clinical acceptability. CONCLUSION: Transthoracic echocardiography is capable of providing accurate data on coronary flow reserve in the distal LAD coronary artery. As a truly noninvasive modality, this technique offers advantages over traditional invasive procedures.
A process, outcome and salary-cost analysis was made of the use of a urinary tract infection/vaginitis protocol. Three nurse practitioners, in a university-based, walk-in clinic, cared for 128 women presenting with complaints of dysuria or vaginal discharge, or both. There were no significant differences among the nurse practitioners in data collection, diagnostic accuracy or patient outcome. The diagnoses were correct in 92 percent, incorrect in 6 percent and indeterminate in 2 percent of the patients. Incorrect diagnoses were due to presumption of urinary tract infection in patients with the urethral syndrome or vaginitis. Of the patients, 78 percent were actually sent home without seeing a physician. Concordance with the nurse practitioners' physical examination was 100 percent in those patients examined by a physician. In 82 percent of the patients there was alleviation of symptoms. Patient satisfaction with this method of care was extraordinary, with 98 percent of the patients giving favorable reports. True physician extension was achieved with a reduction in physician time per patient from 20 minutes to 6 minutes. In contrast to previously reported data, only a modest reduction in salary cost savings (10 percent) could be shown. The author concludes that nurse practitioners working in an acute care clinic or emergency department can see the patients defined in the study and provide high-quality care at a reasonable cost.
OBJECTIVES: To assess the accuracy of a hospital coding database at a busy tertiary referral urological unit. METHODS: Prospectively collected departmental coding data for all urological patients attending the Churchill Hospital, Oxford between 1 May 1999 and 30 April 2000 were compared with the coding data entered by hospital coding clerks on the Oxford Radcliffe NHS Trust database. RESULTS: There were significant discrepancies between the number of patients on the hospital and the departmental database (639 vs 1109). There were gross procedural coding errors in 74 cases. CONCLUSION: Hospital-coded data in this study were incomplete and inaccurate. This has important implications when considering the validity of hospital-trust databases when used as a source for medical research, clinical audit and as a representation of a consultants' clinical workload.
In the analysis of longitudinal pharmacokinetic data, both balanced (equal number of samples per subject) and unbalanced data are used. It is implicitly assumed that the process that caused the missing data can be ignored. A simulation study was performed to determine the effect of ignoring the missing data (i.e., "ignorability") on the accuracy and precision of parameter estimation in longitudinal pharmacokinetic studies. A two-compartment model with multiple intravenous bolus inputs was assumed. Subjects with balanced data sets had six samples, and those with unbalanced data had 1 to 5 samples missing (i.e., supplied in a decreasing order from 5 to 1 samples). The proportion of subjects with 1 to 5 samples missing varied from 25% to 75% in a fixed sample size of 100. The effect of ignorability was studied at intersubject variability ranging from 15% to 60% for a drug assumed to be dosed at its elimination half-life. One hundred replicate data sets of 100 subjects each were simulated for each missing data scenario. The accuracy of parameter estimation was not significantly affected by the amount of ignorable missing data at any given level of variability. However, the precision of parameter estimation was affected by the degree of "missingness."
OBJECTIVES: To examine the reporting accuracy of collateral sources (knowledgeable informants) regarding very mild and mild dementia of the Alzheimer type (DAT) and to identify characteristics associated with collateral source accuracy. DESIGN: Secondary data analysis of initial visits of individuals enrolled in a longitudinal study of healthy aging and Alzheimer disease. SETTING: Urban Alzheimer disease research center. PARTICIPANTS: Pairs of 515 individuals with very mild (n = 203) or mild (n = 312) DAT and their collateral sources. MEASUREMENTS: Collateral sources were asked separately during a semistructured interview by experienced clinicians to report current ability of the individual with DAT in memory, orientation, and judgment and problem solving. The clinical performance of the individuals with DAT in these domains was compared with these predictions. RESULTS: Collateral sources were consistently and significantly accurate in reporting the cognitive capabilities of individuals with very mild and mild DAT. Although all types of collateral sources performed significantly better than chance, individual variables that correlated with collateral source accuracy included spousal relationship; living with the individual with DAT; frequent exposure to the individual; and age, education level, sex and dementia severity of the individual with DAT. CONCLUSION: Collateral sources are accurate in reporting the cognitive capabilities of individuals with DAT, even in the very mild stage of dementia.
PURPOSE: To isolate human prostatic epithelial plasma membranes for the identification of cell surface proteins in the therapeutic targeting of cancer cells while permitting the retrieval of banked samples for clinical purposes. EXPERIMENTAL DESIGN: Radical prostatectomies from 84 patients (median, 61 years; prostate-specific antigen, 5.9; 66% nonpalpable) were processed with alternate, mirror image slices submitted for histology and tissue banking. Benign and malignant foci were macrodissected from the banked sections using the pathologically mapped, mirror image histology sections as a guide. Epithelial plasma membranes were isolated using novel immunomagnetic purification and their purity was assessed. Tissue homogenates were probed by Western blot for malignant (AMACR) and benign (p63) markers to test the accuracy of this protocol. Selected banked tissue slices were retrieved, thawed, and compared pathologically to their corresponding routinely processed alternate slices. RESULTS: Plasma membrane preparations showed the enrichment of epithelial plasma membrane markers (prostate-specific membrane antigen and epithelial-specific antigen) with minimal marker expression from nonepithelial cells or intracellular organelles. Cancer homogenates showed up-regulated AMACR and down-regulated p63, whereas benign homogenates showed up-regulated p63 and down-regulated AMACR. There was 30% benign (p63+) contamination in cancer slices and <6% cancer (AMACR+) contamination in benign slices. Retrieved tissues showed the retention of immunoreactivity while their histology was always adequate for diagnosis. CONCLUSIONS: We have successfully isolated purified epithelial plasma membranes from benign and malignant human prostates and provided validation data for the accuracy of our protocol in a prostate-specific antigen-screened cohort. Our method also enabled the retrieval of banked tissues for clinical purposes with the retention of good histologic and immunohistochemical quality.
OBJECTIVE: Recent legislation in several states providing for civil commitment and preventive detention of sexually violent persons has stirred legal, clinical, and public policy controversies. The mandate for psychiatric evaluation and treatment has an impact on public mental health systems, requiring clinicians and public administrators to direct attention to treatment options. It is a common view that no treatments work for disorders involving sexual aggression. The authors examine this assumption by reviewing research on the effectiveness of treatment for adult male sex offenders. METHODS: MEDLINE was searched for key reviews and papers published during the years 1970 through 1998 that presented outcome data for sex offenders in treatment programs, individual case reports, and other clinically and theoretically important information. RESULTS: Although rigorous research designs are difficult to achieve, studies comparing treated and untreated sex offenders have been done. Measurement of outcome is flawed, with recidivism rates underestimating actual recurrence of the pathological behavior. Outcome research suggests a reduction in recidivism of 30 percent over seven years, with comparable effectiveness for hormonal and cognitive-behavioral treatments. Institutionally based treatment is associated with poorer outcome than outpatient treatment, and the nature of the offender's criminal record is an important prognostic factor. CONCLUSIONS: Although treatment does not eliminate sexual crime, research supports the view that treatment can decrease sex offense and protect potential victims. However, given the limitations in scientific knowledge and accuracy of outcome data, as well as the potential high human costs of prognostic uncertainty, any commitment to a social project substituting treatment for imprisonment of sexual aggressors must be accompanied by vigorous research.
A pharmacokinetic screen has been advocated for the characterization of the population pharmacokinetics of drugs during Phase 3 clinical trials. A common perception encountered in the collection of such data is that the accuracy of sampling times relative to dose is inadequate. A prospective simulation study was carried out to evaluate the effect of error in the recording of sampling times on the accuracy and precision of population parameter estimates from repeated measures pharmacokinetic data. A two-compartment model with intravenous bolus input(s) (single and multiple doses) was assumed. Random and systematic error in sampling times ranging from 5-50% using profile (block) randomized design were introduced. Sampling times were simulated in EXCEL while concentration data simulation and analysis were done in NONMEM. The effect of error in sampling times was studied at levels of variability ranging from 15-45% for a drug assumed to be dosed at its elimination half-life. One hundred replicate data sets of 100 subjects each were simulated for each case. Although estimates of clearance (CL) and variability in clearance were robust for most of the sampling time errors, there was an increase in bias and imprecision in overall parameter estimation as intersubject variability was increased. If there is interest in parameters other than CL, then the design of prospective population studies should include procedures for minimizing the error in the recording of sample times relative to dosing history.