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PubMed1982

Evaluation of a quantitative solid phase reagent system for determination of blood analytes. Experiences with the analytes: LDH, bilirubin, BUN, glucose, and uric acid.

In the first part of the Seralyzer system evaluation the precision and accuracy was studied with a total of 1245 clinical specimens, various commercial control sera, and pooled human sera. The calculated overall precision (between-run, and within-run) and day-to-day precision (% CV) was found to be within 3.0 to 5.4 for glucose, 2.8 to 7.1 for BUN, 1.5 to 6.2 for uric acid, 5.3 to 7.5 for bilirubin, and 3.2 to 8.6 for LDH. The clinical values are in agreement with values from respective comparative methods, as indicated by the regression statistics. The analysis of Seralyzer accuracy data using quality control sera showed in some cases a between-method difference. Supporting studies simulating additional important clinical situations showed that the clinical values for BUN, glucose, and uric acid of approximately 200 specimens from the emergency ward correlated with the respective comparative method values. In this phase of the study we verified that the instrument calibration was stable for a 24-hour period and that there is no effect of module (test) change on precision of Seralyzer determinations. The intra- and inter-laboratory performance in general practitioners' laboratories could be demonstrated using quality control sera.

Bilirubin↗
PubMedDate not supplied

Gender bias in IQ-discrepancy and post-discrepancy definitions of reading disability.

The present study investigated the hypothesis that the higher prevalence of reading disability (RD) often observed among boys is partly an artifact of gender bias in the prediction of reading from IQ. The relevant regression statistics derived from a sample of more than 900 children revealed a statistically significant intercept bias. Predicted reading scores for boys were systematically overestimated, thereby inflating IQ-reading discrepancies; the converse was found for girls. When defined separately for girls and boys, severe underachievement in reading was found to be equally prevalent in both genders and, furthermore, was associated with qualitatively and quantitatively similar patterns of deficits. Because the bias arose from general differences between boys and girls in reading score distributions (a lower mean and greater variance for boys) rather than from differences in IQ scores, gender bias poses a potential threat not only to traditional IQ-discrepancy definitions but also to post-discrepancy definitions that are based solely on reading score cutoffs. Future classification criteria for RD need to take heed of the possibility that when the distributions of reading scores for boys and girls are not identical, performance cutoffs designating low achievement that are based on data pooled from both genders are likely to result in the overidentification of boys with RD and the underidentification of girls with RD.

Adolescent↗
PubMed2004

Knowledge, attitudes, and predictors of advance directive discussions of registered nurses.

The purpose of this study was to describe nurses' knowledge, attitudes, and experiences regarding advance directives. A secondary purpose was to examine predictors of advance directive discussions between nurses and patients. Seven-hundred and nineteen respondents, randomly selected from a list of registered nurses in the state of Ohio, completed mailed questionnaires. Descriptive t test, chi-square, and logistic regression statistics were used in the data analyses. The respondents were knowledgeable and possessed positive attitudes about advance directives. Higher self-perceived confidence in advance directive discussion skills and the experience of caring for at least one patient with a current advance directive were found to be significant predictors of advance directive discussions. These findings suggest that experience with advance directives documents is critical for nurses' comfort and that developing interventions to further nurses' confidence in their discussion skills may increase advance directive discussions.

Adult↗
PubMed2006

Impact of different strategies to control Plasmodium infection and anaemia on the island of Bioko (Equatorial Guinea).

BACKGROUND: On the island of Bioko (Equatorial Guinea), insecticide-treated nets (ITNs) have been the main tool used to control malaria over the last 13 years. In 2004, started an indoor residual spraying (IRS) campaign to control malaria. The purpose of this study is to asses the impact of the two control strategies on the island of Bioko (Equatorial Guinea), with regards to Plasmodium infection and anaemia in the children under five years of age. METHODS: Two transversal studies, the first one prior to the start of the IRS campaign and the second one year later. Sampling was carried out by stratified clusters. Malaria infection was measured by means of thick and thin film, and the packed cell volume (PCV) percentage. Data related to ITN use and information regarding IRS were collected. The Pearson's chi-square and logistic regression statistical tests were used to calculate odds ratios (OR). RESULTS: In the first survey, 168 children were sampled and 433 children in the second one. The prevalence of infection was 40% in 2004, and significantly lower at 21.7% in 2005. PCV was 41% and 39%, respectively. 58% of the children surveyed in 2004 and 44.3% in 2005 had slept under an ITN. 78% of the dwellings studied in 2005 had been sprayed. In the 2005 survey, sleeping without a mosquito net meant a risk of infection 3 times greater than sleeping protected with a net hanged correctly and with no holes (p < 0.05). CONCLUSION: IRS and ITNs have proven to be effective control strategies on the island of Bioko. The choice of one or other strategy is, above all, a question of operational feasibility and availability of local resources.

Anemia↗
PubMed2004

An adaptogenic role for omega-3 fatty acids in stress; a randomised placebo controlled double blind intervention study (pilot) [ISRCTN22569553].

BACKGROUND: There is evidence for an adaptive role of the omega -3 fatty acid, docosahexaenoic acid (DHA) during stress. Mechanisms of action may involve regulation of stress mediators, such as the catecholamines and proinflammatory cytokines. Prevention of stress-induced aggression and hostility were demonstrated in a series of clinical trials. This study investigates whether perceived stress is ameliorated by DHA in stressed university staff. METHODS: Subjects that scored > or = 17 on the Perceived Stress Scale were randomised into a 6-week pilot intervention study. The diet reactive group was supplemented with 6 g of fish oil containing 1.5 g per day DHA, while the placebo group was supplemented with 6 g a day of olive oil. The groups were compared with each other and a wider cross sectional study population that did not receive either active or placebo intervention. RESULTS: There was a significant reduction in perceived stress in both the fish oil and the placebo group from baseline. There was also a significant between-group difference between the fish oil group and the no-treatment controls in the rate of stress reduction (p < 0.05). However, there was not a significant between-group difference between the fish oil and the placebo group, nor the placebo group and the control group. These results are discussed in the context of several methodological limitations. The significant stress reductions in both the fish oil and the placebo group are considered in view of statistical regression, an effect likely to have been exaggerated by the time course of the study, a large placebo effect and the possibility of an active effect from the placebo. CONCLUSION: There were significant differences (p < 0.05) in the fish oil group compared with no-treatment controls. This effect was not demonstrated in the placebo group. As a pilot study, it was not sufficiently powered to find the difference between the fish oil group and the placebo group significant. Further work needs to be undertaken to conclusively demonstrate these data trends. However, the findings from this research support the literature in finding a protective or 'adaptogenic' role for omega-3 fatty acids in stress.

Clinical Trial↗
PubMed2004

Time and frequency domain methods for quantifying common modulation of motor unit firing patterns.

BACKGROUND: In investigations of the human motor system, two approaches are generally employed toward the identification of common modulating drives from motor unit recordings. One is a frequency domain method and uses the coherence function to determine the degree of linear correlation between each frequency component of the signals. The other is a time domain method that has been developed to determine the strength of low frequency common modulations between motor unit spike trains, often referred to in the literature as 'common drive'. METHODS: The relationships between these methods are systematically explored using both mathematical and experimental procedures. A mathematical derivation is presented that shows the theoretical relationship between both time and frequency domain techniques. Multiple recordings from concurrent activities of pairs of motor units are studied and linear regressions are performed between time and frequency domain estimates (for different time domain window sizes) to assess their equivalence. RESULTS: Analytically, it may be demonstrated that under the theoretical condition of a narrowband point frequency, the two relations are equivalent. However practical situations deviate from this ideal condition. The correlation between the two techniques varies with time domain moving average window length and for window lengths of 200 ms, 400 ms and 800 ms, the r2 regression statistics (p < 0.05) are 0.56, 0.81 and 0.80 respectively. CONCLUSIONS: Although theoretically equivalent and experimentally well correlated there are a number of minor discrepancies between the two techniques that are explored. The time domain technique is preferred for short data segments and is better able to quantify the strength of a broad band drive into a single index. The frequency domain measures are more encompassing, providing a complete description of all oscillatory inputs and are better suited to quantifying narrow ranges of descending input into a single index. In general the physiological question at hand should dictate which technique is best suited.

Journal Article↗
PubMed2006

Modelling carbon dynamics from urban land conversion: fundamental model of city in relation to a local carbon cycle.

BACKGROUND: The main task is to estimate the qualitative and quantitative contribution of urban territories and precisely of the process of urbanization to the Global Carbon Cycle (GCC). Note that, on the contrary to many investigations that have considered direct anthropogenic emission of CO2 (urbanized territories produce ca. 96-98% of it), we are interested in more subtle, and up until the present time, weaker processes associated with the conversion of the surrounding natural ecosystems and landscapes into urban lands. Such conversion inevitably takes place when cities are sprawling and additional "natural" lands are becoming "urbanized". RESULTS: In order to fulfil this task, we first develop a fundamental model of urban space, since the type of land cover within a city makes a difference for a local carbon cycle. Hence, a city is sub-divided by built-up, "green" (parks, etc.) and informal settlements (favelas) fractions. Another aspect is a sub-division of the additional two regions, which makes the total number reaching eight regions, while the UN divides the world by six. Next, the basic model of the local carbon cycle for urbanized territories is built. We consider two processes: carbon emissions as a result of conversion of natural lands caused by urbanization; and the transformation of carbon flows by "urbanized" ecosystems; when carbon, accumulated by urban vegetation, is exported to the neighbouring territories. The total carbon flow in the model depends, in general, on two groups of parameters. The first includes the NPP, and the sum of living biomass and dead organic matter of ecosystems involved in the process of urbanization, and namely them we calculate here, using a new more realistic approach and taking into account the difference in regional cities' evolution. CONCLUSION: There is also another group of parameters, dealing with the areas of urban territories, and their annual increments. A method of dynamic forecasting of these parameters, based on the statistical regression model, was already suggested; nevertheless we shall further develop a new technique based on one idea to use the gamma-distribution. This will allow us to calculate the total carbon balance and to show how urbanization shifts it.

Journal Article↗
PubMed1996

Apolipoprotein E genotype does not influence rates of cognitive decline in Alzheimer's disease.

BACKGROUND: Inheritance of the apolipoprotein E (apoE) epsilon 4 allele is a risk factor for developing Alzheimer's disease (AD) and is associated with a lower age of dementia onset. The purpose of this study was to determine whether apoE genotypes differentially influence the course of cognitive decline in AD dementia. METHODS: We administered nine cognitive tests that assessed explicit memory, attention, language, visuospatial function, frontal-lobe function, and logical reasoning abilities to 66 probable AD patients every 6 to 24 months over a span of up to 5.5 years. We identified apoE genotype by a PCR-based method; there were 16 patients with epsilon 3/3, 34 with epsilon 3/4, and 16 with epsilon 4/4. Using regression statistical methods, we computed the change in performance for each test for each patient over time. We then analyzed the mean change in each test in patients grouped according to apoE genotype. RESULTS: For the AD patients as a group, performance on all cognitive tests declined significantly over time, but the rate of decline did not vary significantly across apoE genotypes on any cognitive test. Specifically, the rate of cognitive decline was not faster in patients with an epsilon 4 allele than in those with epsilon 3/3. CONCLUSIONS: These results indicate that the mechanism placing individuals with an epsilon 4 allele at risk for developing AD does not influence the rate of cognitive decline. These observations imply that the influence of apoE epsilon 4 either precedes or occurs at an early point in the AD disease process.

Aged↗
PubMed2006

Task-level control of rapid wall following in the American cockroach.

The American cockroach, Periplaneta americana, is reported to follow walls at a rate of up to 25 turns s(-1). During high-speed wall following, a cockroach holds its antenna relatively still at the base while the flagellum bends in response to upcoming protrusions. We present a simple mechanosensory model for the task-level dynamics of wall following. In the model a torsional, mass-damper system describes the cockroach's turning dynamics, and a simplified antenna measures distance from the cockroach's centerline to a wall. The model predicts that stabilizing neural feedback requires both proportional feedback (difference between the actual and desired distance to wall) and derivative feedback (velocity of wall convergence) information from the antenna. To test this prediction, we fit a closed-loop proportional-derivative control model to trials in which blinded cockroaches encountered an angled wall (30 degrees or 45 degrees ) while running. We used the average state of the cockroach in each of its first four strides after first contacting the angled wall to predict the state in each subsequent stride. Nonlinear statistical regression provided best-fit model parameters. We rejected the hypothesis that proportional feedback alone was sufficient. A derivative (velocity) feedback term in the control model was necessary for stability.

Animals↗
PubMed2004

Do HMO penetration and hospital competition impact quality of hospital care?

This study examines the impact of HMO penetration and competition on hospital markets. A modified structure-conduct-performance paradigm was applied to the health care industry in order to investigate the impact of HMO penetration and competition on risk-adjusted hospital mortality rates (i.e. quality of hospital care). Secondary data for 1957 acute care hospitals in the USA from the 1991 American Hospital Association's Annual Survey of Hospitals were used. The outcome variables were risk-adjusted mortality rates in 1991. Predictor variables were market characteristics (i.e. managed care penetration and hospital competition). Control variables were environmental, patient, and institutional characteristics. Associations between predictor and outcome variables were investigated using statistical regression techniques. Hospital competition had a negative relationship with risk-adjusted mortality rates (a negative indicator of quality of care). HMO penetration, hospital competition, and an interaction effect of HMO penetration and competition were not found to have significant effects on risk-adjusted mortality rates. These findings suggest that when faced with intense competition, hospitals may respond in ways associated with reducing their mortality rates.

Economic Competition↗
PubMed2006

Factors associated with HIV prevalence in a pre-partum cohort of Zambian women.

An ongoing study of mother-to-child human herpes virus-8 (HHV-8) transmission in Zambian women (n = 3160) allowed us to examine the association of medical injections with HIV serostatus while simultaneously accounting for other factors known to be correlated with HIV prevalence. Multi-method data collection included structured interviews, medical record abstraction, clinical examinations, and biological measures. Medically administered intramuscular or intravenous injections in the past five years (but not blood transfusions) were overwhelmingly correlated with HIV prevalence, exceeding the contribution of sexual behaviours in a multivariable logistic regression. Statistically significant associations with HIV also were found for some demographic variables, sexual behaviours, alcohol use, and sexually transmitted diseases (STD). The results confirmed that iatrogenic needle exposure, sexual behaviour, demographic factors, substance use, and STD history are all implicated in Zambian women's HIV+ status. However, the disproportionate association of medical injection history with HIV highlights the need to investigate further and prospectively the role of health-care injection in sub-Saharan Africa's HIV epidemic.

Alcohol Drinking↗
PubMedDate not supplied

Causality and control: threats to internal validity.

The essence of experimental research is to establish causal relationships between variables and this requires internal validity. An experiment is said to have internal validity when extraneous variables have been controlled. However, there are many threats to internal validity. This article considers 13 of them, providing examples which clarify and help to identify under what conditions these threats may occur. The threats discussed are history, maturation, testing, instrumentation, statistical regression, selection mortality, interactions with selection ambiguity about the direction of causal influence, diffusion of imitation of treatments, compensatory equalization of treatments, compensatory rivalry by respondents receiving less desirable treatments and resentful demoralization of respondents receiving less desirable treatments.

Bias↗
PubMed2002

Universal standardization of forearm bone densitometry.

As part of an effort to quantify device-dependent differences in forearm bone density, 101 women, aged 20-80 years (approximately 16 women in each age decade), were scanned on six forearm bone densitometers: the Aloka DCS-600EX, the Hologic QDR-4500A, the Lunar PIXI, the Norland pDEXA, the Osteometer DTX-200, and the Pronosco X-posure System. Regression statistics are reported for all similar regions of interest (ROIs). However, comparisons were confounded because of large differences in the ROI size and placement. The number of ROIs reported for a single scan by each device varied from 1 to 12. The correlation coefficients ranged from 0.7 < r < 0.97, with the highest correlation coefficients and lowest SEs for comparisons between the most similar ROIs. Standardized units of bone mineral density are derived for distal (sdBMD), mid-(smBMD), and proximal (spBMD) ROTs that allow for comparable mean bone densities to be derived for patient populations. Five phantoms were scanned and characterized on five of the devices and the precision and mean values were reported. These phantom values will aid in the in vitro cross-calibration between manufacturers to recreate the presented in vivo relationships. Care should be exercised when using these equations for cross-calibrating patient databases or pooling clinical data from different devices because the least significant differences detectable from measurements taken on two different machines can be increased substantially.

Absorptiometry, Photon↗
PubMed2003

New enzymatic assay for glycohemoglobin.

BACKGROUND: Previous methods to measure glycohemoglobin (GHb) have been time-consuming or imprecise; we therefore developed a new enzymatic assay for GHb. METHODS: Blood cells were first hemolyzed, and hemoglobin was digested with protease to yield fructosyl amino acid. Fructosyl amino acid oxidase acts on the fructosyl amino acid and generates hydrogen peroxide, which reacts with chromogens in the presence of peroxidase. Total hemoglobin was measured spectrometrically in the same reaction tube. The results were reported as the ratio of the concentrations of GHb and hemoglobin. RESULTS: The measured values were comparable to those determined with a HPLC method and with an immunoassay in blood samples from 2854 patients with diabetes. Regression analysis for the enzymatic assay (y) vs the HPLC method (x) produced the following: r = 0.979; slope, 0.994 [95% confidence interval (CI), 0.986-1.001]; y-intercept, 0.04% (95% CI, -0.09% to 0.01%); n = 2854. For the enzymatic assay (y) vs the immunoassay (x), the regression statistics were as follows: r = 0.982; slope, 1.002 (95% CI, 0.995-1.009); y-intercept, 0% (95% CI, -0.05% to 0.05%); n = 2854. CONCLUSIONS: The values measured by the new enzymatic assay are sufficiently correlated with those of the conventional HPLC method and immunoassay, but the proposed assay for GHb is rapid and has high precision.

Amino Acid Oxidoreductases↗
PubMed2006

Angiotensin II type-1 receptor A1166C polymorphism is associated with increased risk of ischemic stroke in hypertensive smokers.

Recent observations revealed a novel role of angiotensin-converting enzyme 2 and the angiotensin II type-1 receptor (AT1R) in lung injury, thereby extending knowledge about the functions of the angiotensin system. Angiotensin II, whose target is the AT1R, is a potent vasoconstrictor. Accordingly, an imbalance leading to enhanced activity of the angiotensin II-AT1R axis is postulated to contribute to both circulatory disturbances and lung injury. In this context, a functional single-nucleotide polymorphism, AT1R A1166C, which leads to enhanced responsiveness of the AT1R, has been postulated as a candidate susceptibility factor for ischemic stroke. The aim of our study was to investigate its occurrence in ischemic stroke and to analyze its possible synergistic associations with clinical risk factors. Genetic and clinical data on 308 consecutive patients with acutely developing ischemic stroke were analyzed. A total of 272 stroke and neuroimaging alteration-free subjects served as a control group. Univariate and logistic regression statistical approaches were used. Alone, the AT1R 1166C allele did not pose a risk of stroke. In hypertensive smokers, however, it was associated with an increased risk of ischemic stroke (OR 22.3, 95% CI 5.8-110.2, p<0.001). Further subgroup analysis revealed the same association for both small-vessel (OR 24.3, 95% CI 6.1-121.1, p<0.001) and large-vessel (OR 21.3, 95% CI 4.6-81.1, p<0.001) infarction. On a pathophysiological basis, our results suggest the possibility that the AT1R A1166C polymorphism might give rise to ischemic stroke indirectly via an unfavorable effect on the cardiorespiratory function.

Adult↗
PubMed2006

Initial treatment of idiopathic nephrotic syndrome in children: prednisone versus prednisone plus cyclosporine A: a prospective, randomized trial.

Previous studies of the Arbeitsgemeinschaft für Pädiatrische Nephrologie in children with steroid-sensitive nephrotic syndrome have shown that the length of initial prednisone therapy has an impact on the subsequent relapse rate. The aim of this randomized, prospective, multicenter study was to reduce the number of relapses further by increasing the initial immunosuppression: Patients with an initial attack of nephrotic syndrome were randomly allocated to treatment with 6 wk of 60 mg/m(2) per d prednisone followed by 6 wk of 40 mg/m(2) per 48 h (Pred group) or to the same prednisone treatment plus 8 wk of cyclosporine (Pred+CsA group). The primary end point was first relapse; follow-up was truncated at 2 yr. In the Pred+CsA group (n = 49 patients), the first relapse occurred later compared with the Pred group (n = 55 patients) (median 22.8 versus 12.5 mo). After 6 mo, 10.4% of patients in the Pred+CsA group experienced a first relapse versus 31.5% in the Pred group (P = 0.01); after 1 yr, 36.5 versus 51% (P = 0.15); and after 2 yr, 51 versus 50%. The mean relapse rate per patient was 0.12 versus 0.57 after 6 mo (P = 0.01), 0.63 versus 1.03 after 1 yr (P = 0.02), and 1.03 versus 2.06 after 2 yr (not significant). The significant benefit for adding CsA was lost after 9 to 12 mo. GFR remained unchanged. The subsequent treatment rate with cyclophosphamide was lower in the CsA group (five versus 12 patients) after 2 yr. With the use of logistic regression statistics, children who were younger than 7 yr show a significantly better sustained remission rate with initial CsA treatment for the 2-yr observation time (P = 0.03). It remains questionable, however, whether the intensified initial treatment with CsA could be recommended generally.

Adolescent↗
PubMed2000

An in vitro study of microleakage of pit and fissure sealants in the presence of occlusal forces.

The purpose of this study was to evaluate the effect of load on microleakage of pit and fissure sealants. In the first phase of the study load of maximal force (F = 880 N) on central and peripheral enamel was applied. Three groups of ten specimens were tested for microleakage. Group A no application of load, Group B application of load on the central pit of the tooth, and Group application of load on the peripheral enamel 2.5 mm away from the margin of the tooth, at the level of dentinoenamel junction. The results of that study showed significant increase of microleakage on the peripheral sealed enamel, as well as enamel microcracks. So, in the phase II sixty wisdom teeth were sealed with Ultra seal XT plus and load of different magnitude was applied on the peripheral enamel. The specimens were thermocycled for 500 cycles at 5 degrees C and 55 degrees C with a dwell of 30 seconds at each temperature prior to load application. Six groups of ten specimens were tested for microleakage under load. The force was applied at the peripheral enamel, 2.5 mm away from the margin of the tooth, at the level of dentin-enamel junction in cross-section view. Group A: F = 0 N; Group B: F = 300 N; Group C: F = 400 N; Group D: F = 500 N; Group E: F = 600 N; Group F: F = 700 N. Microleakage was scored as distance of dye penetration with 0 = no microleakage and 3 = microleakage to underlying fissure. A linear regression statistics was used with R-squared of 0.31. The groups with load applied (B, C, D, E, F) showed statistically significant results (p < 0.05) compared with group A (F = 0 N). Both, the magnitude of the force and tooth morphology may influence the degree of microleakage observed after the placement of sealants.

Bite Force↗
PubMed1978

Liberalized abortion in Oregon: effects on fertility, prematurity, fetal death, and infant death.

An analysis of Oregon Vital Statistics data from 1965 to 1975 was conducted to assess the impact of Oregon's 1969 abortion legislation, which substantially increased the number of reported medically induced abortions. This increase was associated with a slight increase in the age-adjusted 1970 fertility rate and there was no decrease in births to women in the age groups obtaining proportionately the most abortions. A significant and persistent 11 per cent reduction in premature births to women over age 20 (p less than .001) and a 22 per cent reduction in spontaneous fetal deaths (p less than .05) were associated with liberalized abortion. Decreases in neonatal and postneonatal infant mortality were observed, but were indistinguishable from an ongoing trend toward improved infant health. A gradual 25 per cent decline in the age-adjusted fertility rate occurred between 1969 and 1975, but the increase in the number of reported abortions could account for only one-fourth of this decrease. A seven-fold increase in the use of family planning clinics between 1970 and 1973 and more liberalized laws regarding provision of family planning service appeared to account for a much higher proportion of the decreased fertility than did liberalized abortion.

Abortion, Legal↗