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PubMed1992

[Value of combined electro- and vectorcardiography in the estimation of left ventricular mass in the elderly].

Electro- and vectorcardiographic methods describe left ventricle increases only when it has attained a significantly high magnitude, but even in such circumstances the exactitude of such methods is substantially lower than that of echocardiogram (ECHO). On the other hand, in comparison to other age groups, there have been relatively few reports relating electrocardiogram (ECG), vectorcardiogram (VCG) and ECHO with left ventricular mass (LVM) in healthy elderly subjects where increases of the left ventricle mass, if present, would be small or moderate. In this paper LVM as well as LVM index (iLVM) from a group of healthy subjects belonging to a physical training program for elderly, was studied by means of ECHO and computerized ECG and VCG. From ECG, voltage indexes and other LVM associated parameters were extracted; from VCG, planar maximum vectors, areas within VCG loops and maximal spatial magnitude of QRS (SM), were measured. Results of LVM (221 +/- 37.9, g) were higher than figures reported for others groups. Voltage indexes showed normal values, but QRS duration was somewhat prolonged. The best simple linear regression, combining variables from VCG and ECG was maximum horizontal vector (Vmax-Hor) vs Sokolow-Lyon index (SOK) and combining ECHO with ECG or VCG, LVM vs Area inside horizontal loop (AreaHor). A model for estimation of LVM from electrical variables was obtained by multiple linear regression; combining five variables from ECG and VCG. The best model included Sokolow-Lyon index and variables from horizontal and sagittal planes of VCG and spatial magnitude of QRS: LVM = 4.8 SOK-186 VmaxHOR-80 VmaxSAG + 126SM + 340 AreaH + 175.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed2006

Bioactivity of human chorionic gonadotropin produced in frozen-thawed embryo transfer cycles with exogenous hormone replacement.

Human chorionic gonadotropin (HCG) is the glycoprotein hormone in pregnancy. It is known that hCG molecule has a variety of isoforms showing different potency in bioactivity. Taking advantage of rat Leydig cell assay to evaluate hCG bioactivity, we first tried to predict the prognosis of pregnancy in hormone replacement (HR)-cryopreserved embryo transfer cycles. There was no significant difference in serum estradiol (E2) level, immuno-hCG, or bioactive to immunoreactive hCG ratio (b/i) between normal pregnancies and miscarriages at 4 weeks of gestation. Linear regression did not show a significant correlation in E2 or b/i between normal pregnancies and miscarriages. The same analysis was performed on serum samples collected from spontaneously pregnant patients. In normal pregnancies b/i was significantly lower than that in miscarriages while serum E2 was significantly higher. The linear regression analysis was also performed to clarify the correlation between E2 and b/i, and no significant correlation was observed. To confirm the effect of E2 on hCG production, we treated trophoblastic cells with E2. E2 increased the immunoreactivity of hCG to a non-physiologically high concentration; however, it did not change its bioactivity, suggesting that E2 did not change hCG bioactivity by affecting trophoblasts directly. In this study, we presumed it possible to speculate the prognosis of the pregnancy in spontaneous cycles from b/i of hCG, but not in HR cycles. It is suggested that process of hCG secretion could undergo different endocrine regulations between the artificial sex steroid replacement cycles and spontaneous cycles with corpus luteum function.

Animals↗

PubMed1993

Refractive state of aphakic and pseudophakic eyes of dogs.

Streak retinoscopy was performed by 5 ophthalmologists on 256 eyes (191 dogs) to determine their postoperative refractive state after cataract extraction. Aphakic and pseudophakic eyes that had been implanted with 1 of 5 intraocular lenses (IOL) with dioptric powers ranging from +14.5 to +38 diopters (D) were studied. By use of ANOVA, breed and body type of dog and individual performing refraction were found to have no detectable effect on final refractive state. Mean refractive state of aphakic eyes was +14.4 +/- 2.10 D. Mean refractive state for different IOL powers was as follows: +14.5 D IOL = +11.54 +/- 1.18 D (n = 13); +30 D IOL = +5.15 +/- 1.18 D (n = 105); +34.0 D IOL = +3.5 D (n = 1); +36 D IOL = +2.34 +/- 0.73 D 9 (n = 61); and +38 D IOL = +1.41 +/- 0.56 D (n = 28). Residual hyperopia ranged from +0.5 D to +2.5 D with +38 D IOL, and no eyes were myopic (overcorrected) by use of any of the IOL studied. Linear regression analysis of refractive state on IOL power for all dogs predicted that dioptric strength of +41.53 D was necessary to best approximate emmetropia for the population as a whole. Body type of the dog had only slight effect (< 1.0 D) on predicted optimal IOL power. Further linear regression analysis of the 7 breeds studied predicted variations from +39.62 to +43.14 D in IOL powers necessary to approximate emmetropia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1979

Erythrocyte volume and count: a linear relation descriptive of population differences.

In a sample of 215 adult males the mean red cell volume decreases linearly with increasing red cell concentration. The mean corpuscular volume and the red cell count are found uncorrelated with age of subject. Of these subjects 69 are identified as smokers and 114 as nonsmokers. Linear regression analysis shows negative linear relation for the smoking-defined groups, with slopes judged to be no different. When the regression lines are constrained to be parallel the line for smokers is displaced upward by 2.7 fl. No difference is found in mean corpuscular haemoglobin concentration or reticulocyte count. Haematocrit, haemoglobin, mean corpuscular haemoglobin are also reported. Viscosity of blood is greater in smokers. Optical determination of cell volume and area confirms the linear relation of volume and count.

Adolescent↗

PubMed2005

Effect of stent oversizing on in-stent stenosis and lumen size in normal porcine veins.

PURPOSE: To present an in vivo evaluation of the effects of stent oversizing on in-stent stenosis and on actual lumen size in normal veins. METHODS: Twelve self-expanding stents were implanted in the common iliac veins of 6 minipigs, which were divided in 2 groups for follow-up at 1 and 3 months, respectively. Oversizing ranged from 119.5% to 216% of the original vessel diameter. Intravascular ultrasound (IVUS) was used to measure vessel areas at the stent edges and midpoint. In-stent stenosis and decrease in actual lumen size were evaluated with IVUS immediately after implantation and during follow-up. RESULTS: There was a very strong positive linear regression between stent oversizing and in-stent stenosis in the 1-month model (r=0.947, p=0.004), in the 3-month model (r=0.931, p=0.007), and in the sum of these 2 groups (r=0.83, p<0.001). Regarding the change in actual lumen size, we found a strong negative linear regression with stent oversizing in the 1-month (r=-0.754, p=0.083) and the 3-month (r=-0.562, p=0.246) groups, but these did not attain statistical significance. However, a strong correlation between stent oversizing and a decrease in lumen size in all samples proved to be statistically significant (r=0.619, p=0.032). CONCLUSIONS: Stent oversizing was strongly correlated with increased in-stent stenosis and decreased actual lumen size at follow-up in normal non-stenotic porcine veins.

Analysis of Variance↗

PubMed2004

Bone density and hemoglobin levels in older persons: results from the InCHIANTI study.

Hypoxemia has been recognized as a risk factor for bone loss. The aim of the present study is to investigate the relationship of bone mass and density measures with anemia and hemoglobin levels in a large sample of older community-dwelling persons. The study is based on data from 950 participants enrolled in the "Invecchiare in Chianti" (Aging in the Chianti area, InCHIANTI) study. All the analyses were performed considering continuous hemoglobin levels as well as the dichotomous anemia variable (defined according to WHO criteria as hemoglobin < 12 g/dl in women and < 13 g/dl in men). A peripheral quantitative computerized tomography (pQCT) scan of the right calf was performed in all participants to evaluate total bone density, trabecular bone density, cortical bone density, and the ratio between cortical and total bone area. Linear regression analyses were used to assess the multivariate relationship of pQCT bone measures with anemia and hemoglobin levels after adjustment for demographics, chronic conditions, muscle strength and biological variables. Participants were 75.0 (SD 6.9) years old. In our sample, 101 participants (10.6%) were anemic. In women, coefficients from adjusted linear regression analyses evaluating the association between pQCT bone measures (per SD increase) and hemoglobin levels/anemia showed significant associations of anemia with total bone density (beta = -0.335, SE = 0.163; P = 0.04) and cortical bone density (beta = -0.428, SE = 0.160; P = 0.008). Relationships with borderline significance were found for the associations of anemia with trabecular bone density and the ratio between cortical and total bone area. Significant associations were found between hemoglobin levels and trabecular bone density (beta = 0.112, SE = 0.049; P = 0.02), total bone density (beta = 0.101, SE = 0.046; P = 0.03), cortical bone density (beta = 0.100, SE = 0.046; P = 0.03) and the ratio between cortical bone and total area (beta = 0.092, SE = 0.045; P = 0.04). In men, significant associations were found for hemoglobin levels with total bone density (beta = 0.076, SE = 0.036; P = 0.03) and cortical bone density (beta = 0.095, SE = 0.41; P = 0.02). A borderline significance was reported for the association between anemia and cortical bone density. We concluded that anemia and low hemoglobin levels are negatively and independently associated with bone mass and density. The bone loss associated with hemoglobin levels mainly occurs in the cortical bone. Women with lower hemoglobin levels demonstrate a higher bone loss than male counterparts.

Aged↗

PubMed2003

Prediction of human blood: air partition coefficient: a comparison of structure-based and property-based methods.

In recent years, there has been increased interest in the development and use of quantitative structure-activity/property relationship (QSAR/QSPR) models. For the most part, this is due to the fact that experimental data is sparse and obtaining such data is costly, while theoretical structural descriptors can be obtained quickly and inexpensively. In this study, three linear regression methods, viz. principal component regression (PCR), partial least squares (PLS), and ridge regression (RR), were used to develop QSPR models for the estimation of human blood:air partition coefficient (logPblood:air) for a group of 31 diverse low-molecular weight volatile chemicals from their computed molecular descriptors. In general, RR was found to be superior to PCR or PLS. Comparisons were made between models developed using parameters based solely on molecular structure and linear regression (LR) models developed using experimental properties, including saline:air partition coefficient (logPsaline:air) and olive oil:air partition coefficient (logPolive oil:air), as independent variables, indicating that the structure-property correlations are comparable to the property-property correlations. The best models, however, were those that used rat logPblood:air as the independent variable. Haloalkane subgroups were modeled separately for comparative purposes and, although models based on the congeneric compounds were superior, the models developed on the complete set of diverse compounds were of acceptable quality. The structural descriptors were placed into one of three classes based on level of complexity: topostructural (TS), topochemical (TC), or three-dimensional/geometrical (3D). Modeling was performed using the structural descriptor classes both in a hierarchical fashion and separately. The results indicate that highest quality structure-based models, in terms of descriptor classes, were those derived using TC descriptors.

Animals↗

PubMed1986

Improving the predictability of intraocular lens power calculations.

We reviewed the intraocular lens power calculations on 512 posterior chamber lens implantations and determined four ways to reduce the estimated 5% incidence of large postoperative refractive "surprises" (greater than 2 diopters [D]): First, preoperatively identify those patients who have greater than a 1-D difference between the theoretical and linear regression formulas. Second, repeat axial length and corneal power measurements in these patients to eliminate random error. Third, develop an individualized theoretical formula that accounts for constant bias. Fourth, encourage manufacturers to improve instrumentation for measuring corneal power and axial length. We also examined the disparity between the linear regression formula and the curvilinear theoretical formula.

Anterior Chamber↗

PubMed1985

Postnatal enlargement of human tracheobronchial airways and implications for particle deposition.

In support of predictions for inhaled particle deposition, morphometric measurements were taken on 20 replica airway casts of people aged 11 days to 21 years. Measurements of right upper lobe airway lengths, diameters, and branching angles were made such that a growth model suitable as input to predictive equations for particle deposition efficiency was obtained. The tracheobronchial airways growth was describable by linear regressions on body length. The length-to-diameter ratio of growing airways did not change in any simple way as a function of airway generation. Airflow rates for a given state of physical activity for various ages were found from previously published data to be describable by linear regressions on body mass. Three states of physical exertion-low activity, light exertion, and heavy exertion-were used for modeling purposes. The computed particle deposition efficiencies indicate that under most circumstances smaller (younger) people will have greater tracheobronchial deposition efficiencies than larger (older) people. For example, tracheobronchial dose on a per kilogram body mass basis for 5-micron-diameter particles may be more than 6 times higher in the resting newborn than in the resting adult assuming equivalent deposition efficiencies above the larynx.

Adolescent↗

PubMed1997

High resolution magnetic resonance imaging of the calcaneus: age-related changes in trabecular structure and comparison with dual X-ray absorptiometry measurements.

A high-resolution magnetic resonance imaging (MRI) protocol, together with specialized image processing techniques, was applied to the quantitative measurement of age-related changes in calcaneal trabecular structure. The reproducibility of the technique was assessed and the annual rates of change for several trabecular structure parameters were measured. The MR-derived trabecular parameters were compared with calcaneal bone mineral density (BMD), measured by dual X-ray absorptiometry (DXA) in the same subjects. Sagittal MR images were acquired at 1.5 T in 23 healthy women (mean age: 49.3 +/- 16.6 [SD]), using a three-dimensional gradient echo sequence. Image analysis procedures included internal gray-scale calibration, bone and marrow segmentation, and run-length methods. Three trabecular structure parameters, apparent bone volume (ABV/TV), intercept thickness (I.Th), and intercept separation (I.Sp) were calculated from the MR images. The short- and long-term precision errors (mean %CV) of these measured parameters were in the ranges 1-2% and 3-6%, respectively. Linear regression of the trabecular structure parameters vs. age showed significant correlation: ABV/TV (r2 = 33.7%, P < 0.0037), I.Th (r2 = 26.6%, P < 0.0118), I.Sp (r2 = 28.9%, P < 0.0081). These trends with age were also expressed as annual rates of change: ABV/TV (-0.52%/year), I.Th (-0.33%/year), and I.Sp (0.59%/year). Linear regression analysis also showed significant correlation between the MR-derived trabecular structure parameters and calcaneal BMD values. Although a larger group of subjects is needed to better define the age-related changes in trabecular structure parameters and their relation to BMD, these preliminary results demonstrate that high-resolution MRI may potentially be useful for the quantitative assessment of trabecular structure.

Absorptiometry, Photon↗

PubMed2000

Alpha-synuclein-immunoreactive cortical Lewy bodies are associated with cognitive impairment in Parkinson's disease.

Amygdala, hippocampus and six cortical gyri were examined for the Lewy body (LB) degeneration and Alzheimer's disease (AD) type changes in 45 patients with Parkinson's disease (PD). For detection of LBs, the brain areas were stained with an antibody against alpha-synuclein. The extent of neuropathological lesions was investigated in relation to cognitive dysfunction and apolipoprotein E (apoE) epsilon4 allele dosage. At least one cortical LB was found in 95% of cases (43/45). Furthermore, 40% of cases (18/45) had histological findings of definite AD (CERAD class C). Those PD cases with the apoE epsilon4 allele had a significantly greater number of cortical LBs than those without the apoE epsilon4 allele, but this was statistically significant only in precentral, angular and temporal gyri. The LB density correlated better with the number of plaques than with the density of tangles. The number of LBs in several cortical areas correlated significantly with the cognitive impairment. In stepwise linear regression analysis, the number of LBs in the cingulate gyrus and the amount of tangles in the temporal cortex remained statistically significant. When the CERAD class C was excluded, the correlation between cognitive decline and the number of LBs in cortical areas became even more pronounced. A stepwise linear regression analysis in these cases found the number of LBs in the frontal gyrus to be the statistically most significant predictor of cognitive impairment. This study shows, for the first time, that in PD, alpha-synuclein-positive cortical LBs are associated with cognitive impairment independent of AD-type pathology.

Aged↗

PubMed2005

An evaluation of clinical accuracy of the EasyTouch blood uric acid self-monitoring system.

OBJECTIVES: Self-monitoring blood uric acid device is an important tool for patients to efficiently monitor their blood uric acid concentrations. The objective of the present study was to evaluate the accuracy of EasyTouch uric acid monitoring system. DESIGN AND METHODS: Capillary blood uric acid concentrations measured using EasyTouch and the reference values obtained from COBAS MIRA were performed in the Department of Laboratory Medicine, Wei-Gong Memorial Hospital. Results were evaluated using (1) linear regression analysis, (2) percentage of readings within a defined range of deviation from the reference value, and (3) coefficients of variation (CVs) calculated from 60 measurements in series. RESULTS: The window of the 177 EasyTouch readings covered a wide range from 0.1785 to 0.6367 mmol/L (3-10.7 mg/dL). Linear regression analysis yielded a regression slope of 0.975, an intercept of 0.0118 mmol/L and an R2 of 0.8966. Of the EasyTouch readings, 64 (36.2%), 61 (34.5%), 34 (19.2%), 9 (5.08%), and 9 (5.08%) were within the intervals of <5%, 5-10%, 10-15%, 15-17%, and >17%, respectively, of the reference values. Further analysis for the performance of each lot of strips showed that both coefficients of correlation and the percentages of readings within the CLIA's criterion (+/-17%), respectively, were in a narrow range from 0.8777 to 0.9541 and from 92.1% to 100%. The CVs for the seven lots of strips (lot 1 to lot 7) ranged from 2.93% to 6.33%, 3.2% to 5.9%, 3.64% to 7.0%, 2.84% to 7.6%, 2.68% to 5.42%, 3.03% to 6.93%, and 3.18% to 5.17%, respectively. CONCLUSION: EasyTouch is an acceptable diagnostic device which provides accurate uric acid measurements.

Adult↗

PubMed2002

Cadmium accumulation and metallothionein synthesis in freshwater bivalves (Pyganodon grandis): relative influence of the metal exposure gradient versus limnological variability.

The relative influence of limnological confounding factors on cadmium (Cd) bioaccumulation and metallothionein (MT) synthesis was quantified in natural populations of freshwater bivalves (Pyganodon grandis) living in lakes along a Cd concentration gradient. During the ice-free period, we measured 15 environmental variables in the water compartment and determined total concentrations of Cd and MT in the gills of bivalves at 37 littoral stations in 20 lakes distributed across the mining area of Rouyn-Noranda in northwestern Quebec. A multiple linear regression model including pH (+), dissolved Ca concentrations (-) and free Cd2+ concentrations at the sediment-water interface (+) explained 74% of the variability in Cd concentrations in the bivalve gills. Dissolved Ca (-) and free Cd2+ (+) together explained 62% of the variation in MT concentrations in the bivalve gills. Partial linear regression analyses indicated that the limnological factors' pure and shared effects together accounted for 48 and 45% of the total variation in Cd and MT concentrations in the gills, respectively. A lake selection procedure that could be applied in monitoring programs is proposed to minimise the relative influence of these confounding variables.

Animals↗

PubMed1987

Statistical models for the twinning rate.

Linear regression models are used to explain the variations in the twinning rates. Data sets from different countries are analysed and maternal age, parity and marital status are the main regressors. The model building technique is also used in order to study the secular decline in the twinning rate. Linear regression technique makes it possible to compare the effect of different factors but the method requires sufficiently disaggregated data.

Australia↗

PubMed1994

Hyperuricemia and insulin resistance.

The associates of gout-obesity, hypertriglyceridemia, glucose intolerance, and hypertension, strikingly resemble those of insulin resistance. In the present study we determined whether hyperuricemia is associated with insulin resistance and, if so, whether this association can be explained by other components of the syndrome. For this purpose we quantitated insulin sensitivity (euglycemic clamp) in 37 nondiabetic subjects (aged 30-68 yr) exhibiting varying degrees of the metabolic syndrome (body mass index, 21.5-35.7 kg/m2; serum triglycerides, 0.4-22.0 mmol/L; high density lipoprotein cholesterol 0.38-1.86 mmol/L; blood pressure, 190-100/116-60 mm Hg). In simple linear regression analysis, the serum uric acid concentration (range, 182-568 mumol/L) was inversely correlated with insulin sensitivity (rate of glucose utilization; r = -0.61; P < 0.001) and positively with serum triglycerides (r = 0.68; P < 0.001), but not with body mass index, age, or the plasma glucose concentration. In multiple linear regression analysis, both insulin sensitivity (P < 0.05) and serum triglycerides (P < 0.005) were independently associated with the serum uric acid concentration, and together explained 50% of its variation. Addition of body mass index or age to the model did not improve the degree of explanation. Acute elevation of serum triglycerides about 3-fold, of plasma FFA about 9-fold, or of serum insulin about 28-fold had no effect on the serum uric acid concentration in healthy volunteers. The data indicate that hyperuricemia is indeed an inherent component of the metabolic syndrome and could also be used as a simple marker of insulin resistance.

Adult↗

PubMed1983

[Quantitative aortic flow and cardiac output volume determinations in rabbits using tetrapolar impedance plethysmography].

In 25 normal rabbits the transthoracic impedance changes were continually registered at rest and during pharmacological exercise by use of various types of electrodes. These changes were quantified by the formula of Kubicek for estimation of cardiac output. The obtained values were compared with the values of cardiac output and the flow in the aorta descendens measured by electromagnetic flowmetry in the aorta descendens. Linear regression analyses for several intervals of ejection and various types of electrodes showed a high and significant correlation between the values estimated by both methods (r greater than or equal to 0.96, p less than or equal to 0.001). The analyses of confidence intervals of the parameters of linear regression showed that the functional relations can be described by uniform parameters of regression. On this basis were estimated coefficients of correction which allow quantitative evaluation of the cardiac output and the flow in the aorta descendens in rabbits by use of tetrapolar impedance plethysmography. For cardiac output: (Formula: see text) for the flow in the aorta descendens: (Formula: see text) Tetrapolar impedance plethysmography is a noninvasive method, which allows quantitative and dynamic evaluation both of the cardiac output and the flow in the aorta descendens in rabbits.

Animals↗

PubMed1996

Are retrospective peer-review transfusion monitoring systems effective in reducing red blood cell utilization?

OBJECTIVE: This research used a study-control group design and examined data collected from five hospitals to evaluate the effectiveness of retrospective peer-review systems on reducing utilization of red blood cells (RBCs). DESIGN: The effects of retrospective peer-review systems were studied in three parts: (1) trends of RBC utilization were compared by the slopes of linear regression lines that assessed the effect of time on RBC utilization among four study hospitals and one control hospital, (2) diagnosis-specific RBC utilization was compared between the control hospital and one matched study hospital, and (3) the effect of the retrospective review system of one study hospital was assessed by linear regression using data accumulated 1 year before and 2 years after implementation of the program. RESULTS: Three study hospitals showed no significant changes in RBC utilization during the 10-month study period. One study hospital and the control hospital demonstrated trends of reduced RBC use with negative slopes of regression lines; however, there was no difference in the degree of the two slopes, and the diagnosis-specific RBC utilization was not lower at the study hospital than at the control hospital. Furthermore, implementation of the retrospective peer-review system at one study hospital demonstrated no effect on RBC utilization. CONCLUSIONS: We conclude that the retrospective peer-review systems implemented at these four hospitals had no effect on reducing red blood cell utilization.

Erythrocyte Transfusion↗

PubMedDate not supplied

[Psychosocial workload, sick leave, and health-related well being: an empirical study from the perspective of gender research].

PURPOSE: The aim of this study was to test hypotheses on the consequences of gender role expectations with regard to the extent of work stress, selected health-related measures and their associations. METHOD: Data on psychosocial workload (questionnaire of effort-reward imbalance), sick leave (self-reports of the duration of medically certified sick leave during the past two years) and health-related well being were collected in a representative sample of German full-time employees (n = 666). Hypotheses were tested using analyses of variance (ANOVA) and covariance (ANCOVA) and moderated linear regression analyses. RESULTS: Women reported lower health-related well-being as compared to men while effort-reward imbalance and sick leave did not differ between the sexes. Parents reported slightly longer durations of sick leave during the past two years than childless participants (not significant). The results of stratified linear regression analyses show stronger associations between effort-reward imbalance and both health-related measures for women with children than for men with children, while single men and women do not differ in this regard. CONCLUSIONS: Evidence of this kind can be useful for the purposeful planning and implementation of health promotion measures at work. Women with children would be a group deserving special attention. The findings also point to continuing differences in gender role expectations in the family context.

Adolescent↗