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PubMed2005

Incidence of splayleg pigs in Nebraska litter size selection lines.

Genetic parameters for the splayleg (SL) condition were estimated from 37,673 records of pigs from six lines derived from a Large White-Land-race base population. Random selection for 22 generations was practiced in Lines C1 and C2. Line C2 was derived from C1 at Generation 8. Selection lines were as follows: 1) Line I, selected 11 generations for an index of ovulation rate and embryonic survival followed by 11 generations of selection for litter size; 2) Line IOL, derived from Line I at Generation 8 and which underwent eight generations of two-stage selection for ovulation rate and number of fully formed pigs per litter followed by four generations of litter size selection; 3) Line COL, derived from Line C1 at Generation 8 and selected eight generations in two stages for ovulation rate and number of fully formed pigs followed by four generations of litter size selection; and 4) Line T, selected 12 generations for increased testis size. From logistic models, it was found that boars were 224% more likely to have SL than gilts (P < 0.01). Decreases in birth weight, dam age at puberty, dam nipple number, and dam embryonic survival, and increases in dam litter size and inbreeding increased the odds of SL (P < 0.05). Direct and maternal heritabilities of SL were 0.07 and 0.16, respectively, and the correlation between direct and maternal effects was -0.24. Correlations between direct genetic effects for SL and number born alive, nipple number, birth weight, age at puberty, and embryonic survival were -0.19, -0.36, 0.23, -0.19, and -0.32, respectively. Except for the correlation of 0.32 between maternal effects for SL and direct effects for number of live pigs, correlations of SL maternal genetic effects with direct genetic effects of other traits were less than 0.11. Annual direct genetic trends (%) for SL in I, IOL, COL, T, C1, and C2 were -0.003 +/- 0.003, 0.121 +/- 0.012, -0.273 +/-0.009, 0.243 +/-0.014, -0.274 +/-0.004, and 0.086 +/-0.008, respectively; annual maternal genetic trends (%) were 0.106 +/-0.004, 0.508 +/-0.019, 0.383 +/-0.015, 0.527 +/-0.024, 0.188 +/-0.005, and 0.113 +/-0.012, respectively. Annual genetic maternal trend in Line I after Generation 12 was 0.339 +/-0.014. Maternal breeding value for SL is expected to increase as a correlated response to selection for increased litter size and increased size of testes.

Animals↗

PubMed2003

Fractional esterification rate of cholesterol and ratio of triglycerides to HDL-cholesterol are powerful predictors of positive findings on coronary angiography.

BACKGROUND: We examined the predictive value of various clinical and biochemical markers for angiographically defined coronary artery disease (aCAD). Specifically, we assessed the value of the ratio of plasma triglyceride (TGs) to HDL-cholesterol (HDL-C) and the fractional esterification rate of cholesterol in plasma depleted of apolipoprotein B (apoB)-containing lipoproteins (FER(HDL)), a functional marker of HDL and LDL particle size. METHODS: Patients (788 men and 320 women) undergoing coronary angiography were classified into groups with positive [aCAD(+)] and negative [aCAD(-)] findings. Patient age, body mass index, waist circumference, blood pressure (BP), medications, drinking, smoking, exercise habits, and plasma total cholesterol (TC), LDL-cholesterol (LDL-C), HDL-unesterified cholesterol, HDL-C, TGs, FER(HDL), apoB, log(TG/HDL-C), and TC/HDL-C were assessed. Lipids and apoproteins were measured by standard laboratory procedures; FER(HDL) was determined by a radioassay. RESULTS: Members of the aCAD(+) group were older and had a higher incidence of smoking and diabetes than those in the aCAD(-) group. The aCAD(+) group also had higher TG, apoB, FER(HDL), and log(TG/HDL-C) and lower HDL-C values. aCAD(+) women had greater waist circumference and higher plasma TC and TC/HDL-C. aCAD(+) men, but not women, had higher plasma LDL-C. In the multivariate logistic model, the significant predictors of the presence of aCAD(+) were FER(HDL), age, smoking, and diabetes. If only laboratory tests were included in the multivariate logistic model, FER(HDL) appeared as the sole predictor of aCAD(+). Log(TG/HDL-C) was an independent predictor when FER(HDL) was omitted from multivariate analysis. CONCLUSIONS: FER(HDL) was the best laboratory predictor of the presence of coronary atherosclerotic lesions.

Adolescent↗

PubMed1984

Diet, prevalence and 10-year mortality from coronary heart disease in 871 middle-aged men. The Zutphen Study.

The Zutphen Study is a longitudinal investigation among middle-aged men of relationships between diet, other risk characteristics, and coronary heart disease (CHD). In 1960, dietary data were collected by the cross-check dietary history method. CHD mortality data were collected during 10 years of follow-up. The 14 men with CHD at baseline consumed 524 kcal/day less than the 857 CHD-free men. During 10 years of follow-up, 30 men who were initially free of CHD died from CHD. Those men consumed 273 kcal/day less than men who did not die from CHD. The inverse relationship between energy intake and CHD became stronger when energy intake was expressed per kg of body weight. Dietary cholesterol per 1000 kcal was significantly positively related to CHD, while vegetable protein, polysaccharides, and dietary fiber were significantly inversely related to CHD. These relationships were no longer statistically significant when energy intake per kg of body weight was added to the logistic model. The inverse relationship between energy intake per kg of body weight and CHD became insignificant when subscapular skinfold and serum cholesterol were added to the logistic model. It is concluded that the influence of energy intake per kg of body weight on CHD is mediated through other risk characteristics: subscapular skinfold and serum cholesterol.

Adult↗

PubMedDate not supplied

Analysis of the recourse to conservative surgery in the treatment of breast tumors.

AIMS AND BACKGROUND: Conservative surgery is the treatment of choice for malignant tumors, at least up to stage II. The aim of this study was to analyze the recourse to conservative surgery for breast tumors and its determinants (ie, characteristics of hospitals and patients). METHODS: The study was conducted in Italy's Lazio region and was based on administrative data of the regional Hospital Information System, a database on hospitalizations. We selected all regional hospitalizations for therapeutic breast surgery over 1997, classifying them as either "conservative" or "non-conservative". The other variables considered were type of hospital, number of beds, volume of activity (average annual number of hospitalizations for breast cancer surgery), specific diagnosis, severity of cancer, and patient's age, place of residence, and socioeconomic level. A logistic model was used for multivariate analysis. RESULTS: A total of 7235 hospitalizations were analyzed, 3570 (49%) for malignant tumors and 3665 (51%) for benign disease. The logistic model showed that the factors most closely correlated with conservative surgery were age (OR = 2.2; 95% Cl: 1.8-2.6, for the age group <50 years compared to >70 years); severity of cancer (OR = 0.6; 95% Cl: 0.5-0.8, for non-localized compared to localized tumors), and volume of activity of the hospital (OR = 1.3; 95% CI: 1.0-1.6, for hospitals with >70 operations/year compared to those with <20 operations/year). The study also revealed that surgery for malignant tumors was performed by both high-volume and low-volume hospitals throughout the region. CONCLUSIONS: The association between conservative surgery and younger age, even after controlling for the severity of cancer, points to the need to encourage adherence to the existing guidelines. The association between conservative surgery and high-volume hospitals and the finding that a high proportion of breast operations is performed in low-volume facilities suggest that further efforts should be made to promote admission to high-volume hospitals.

Adult↗

PubMed2002

A case study of logistic QSAR modeling methods and robustness tests.

Acute toxicity (15-min EC(50)) determination of 16 substituted naphthalene compounds to Photobacterium phosphoreum was undertaken according to the standard procedures, while the effects of molecular structures of selected compounds on their toxicity to test microorganisms were logistically conducted using the quantitative structure-activity relationship (QSAR) technique. The relationship was developed as -log EC(50)=5.5916 (+/-0.1189)-7.4893(+/-0.4900)qH(+)+0.7771(+/-0.0619E(lumo)+0.0088(+/-0.0009)alpha(N=16, R(2)(adj)=0.9698, SE=0.0892, P=0.0000). The cluster analyses of individual structure descriptors as well as the quality control chart and Monte Carlo simulation test indicated that the prediction model was reasonable and robust even if tested with several different methods. Furthermore, the quantum chemical parameters entering into the QSAR model were used to discuss the possible toxicity pathways, and the results revealed that the selected compounds were reactive and their toxicity behaviors were complex processes containing physical partition stages as well as biochemical reaction stages.

Lethal Dose 50↗

PubMed1995

Detection of dementia of the Alzheimer type in a population-based sample: neuropsychological test performance.

The ability to detect dementia of the Alzheimer type (DAT) in a community-dwelling sample of elderly individuals on the basis of neuropsychological test performance was examined. Three hundred sixty community-dwelling individuals were identified by neurological examination as having probable or possible Alzheimer's disease, being at risk for Alzheimer's disease, or having no cognitive impairment. A logistic model comprised of tests of verbal and nonverbal memory, mental flexibility, and confrontation naming correctly classified 82% of DAT subjects and 98% of normal elderly subjects. The logistic model classified 77% of subjects who were diagnosed as at risk for Alzheimer's disease as being cognitively normal. A cross-validation with a clinically based sample of subjects correctly classified 89% of DAT patients and 100% of normal control subjects. The results suggest that psychometric discrimination of dementia may be less accurate in community-dwelling populations than in clinically based samples.

Adult↗

PubMed1999

Creating performance categories from continuous motor skill data using a Rasch measurement model.

This paper reports the use of the Extended Logistic Model (ELM) of Rasch (Andrich, 1988), based on Item Response Theory, to validate the reduction of continuous motor skill data to categories of performance. The data were gathered from the performances of 5 and 6 year old children on 24 fundamental movement skills and involved different measurement units such as seconds, centimetres, scores and counts. In order to compare results across all skills the data were collapsed into discrete sets of categories. Several alternative cut-off locations based on normative data were considered. A feature of the ELM is that it can account for correct scoring of the response categories, but only if the threshold estimates derived from the data by the measurement model are correctly ordered in a hierarchical fashion, from lowest to highest. Should this be the case, a valid scoring function has been established. In this study, the data were successfully reduced to three categories based on the 15th and 85th percentile allowing further analysis to proceed.

Child↗

PubMed1989

The relative influence of selected social factors on Korean drinking behavior in Los Angeles.

The purpose of this study was twofold: to identify characteristics distinguishing Korean-American drinkers from abstainers and to clarify differences between those who drink smaller versus larger amounts of alcohol. A random sample of 280 Korean adults was interviewed using a schedule based on Cahalan's national study of drinking behavior and attitudes. Approximately 58% of the sample were abstainers while only about 14% were heavy drinkers. Logistic regression was used to determine the relative influence of various social factors on drinking behavior. The logistic model identified five characteristics which differentiated abstainers from drinkers: gender (male), college education, parental opposition, playing indoor games (e.g., cards) and going to bars, and/or nightclubs. A second logistic model clarified the influence of similar characteristics on the level of drinking. Males and those who went to bars and/or nightclubs were most apt to be heavy drinkers whereas participants in sports and Protestants were aligned with more moderate drinking.

Acculturation↗

PubMed1989

Logistic regression model for the assessment of microalbuminuria and microproteinuria in insulin-dependent diabetic patients at risk.

Diabetic microalbuminuria, which predisposes to the irreversible macroproteinuria and terminal renal failure, has been shown to be reversible by stringent metabolic control. In this study, using logistic regression, 23 patients with insulin-dependent diabetes mellitus were evaluated. Basing on the reported biochemical changes in patients with diabetes mellitus, the relationship between microalbuminuria and serum biochemistries was assessed. Four biochemical parameters were shown to be significantly related to the amount of microalbuminuria and microproteinuria. The microalbuminuria as assayed by rocket immunoelectrophoresis is closely correlated with the microproteinuria as measured by the Coomassie dye binding method and both have a significant relationship with plasma creatinine, bicarbonate, albumin and globulin as assessed by the Minitab computer program and the Biomedical Data Package--Logistic Regression computer program. The relationship with bicarbonate and creatinine can be due to a decrease in glomerular filtration rate associated with more advanced microproteinuria. The relationship with albumin and globulin is the result of impaired albumin synthesis by the liver in diabetes mellitus. From these data, two simple equations which can provide a relative risk factor with rough quantitative assessment for microproteinuria and microalbuminuria are derived. Thus, from these four parameters available from relatively simple blood biochemistries, assessment can be made of the severity of coexisting diabetic proteinuria. The measurement of the latter is not readily available and is more costly and tedious. This assessment together with the finding of a decrease in albumin, slight increase in creatinine and decrease in bicarbonate associated with the more severe microalbuminuria can be used to alert the diabetologist in implementing tighter metabolic control and other interventional methods before irreversible macroproteinuria develops.

Adult↗

PubMed1993

A modelling approach to the analysis of menstrual diary data.

In clinical trials to compare contraceptives, women are usually asked to record whether or not each day is a bleeding day over the duration of the trial. In this paper we describe how parametric models, which include terms corresponding to covariates recorded for each woman, can be used to analyse data on the occurrence of certain adverse events identified from the diary record. Linear logistic models are used to analyse the probability of prolonged bleeding or amenorrhoea, and log-linear models are used to analyse the lengths of bleeding episodes. In both cases variation between women is allowed for by including a random effect in the model. The application of our methods is illustrated using a data base made available by the World Health Organization.

Bias↗

PubMed1997

Designing and analysing case-control studies to exploit independence of genotype and exposure.

Genetic susceptibility and environmental exposures play a synergistic role in the aetiology of many diseases. We consider a case-control study of a rare disease in relation to a categorical exposure and a genetic factor under the assumption that the genotype and the exposure occur independently in the population under study. Using a logistic model for risk, we describe maximum likelihood methods based on log-linear models that explicitly impose the independence assumption, something the usual logistic regression analyses cannot do. The estimator of the genotype-exposure interaction effect depends only on data from cases. Estimators for genotype and for exposure effects depend also no data from controls, but only through their respective marginal totals. All three estimators have smaller variance than they would were independence not enforced. These results have important implications for design: (i) Case-only studies can efficiently estimate gene-by-environment interactions. (ii) Studies where controls are genotyped anonymously can estimate genotype, exposure, and interaction effects as efficiently as designs where genotype and exposure data are linked. This feature addresses a growing concern of human subjects review boards. (iii) Exposure and interaction effects, but not genotype effects, can be estimated from studies where genetic information is only collected from cases (although one can recover the genotype effect if external gene prevalence data exist). Such designs have the compensatory benefit that the response rate (hence, validity) is higher when controls are not subjected to intrusive tissue sampling. However, the independence assumption can be checked only with linked genotype and exposure data for some controls. We illustrate the methods by applying them to recent study of cleft palate in relation to maternal cigarette smoking and to a variant of the transforming growth factor alpha gene in the child.

Case-Control Studies↗

PubMed1988

Prevalence of respiratory symptoms and diseases in schoolchildren living in a polluted and in a low polluted area in Israel.

Second and fifth grade schoolchildren living in two communities with different levels of air pollution were studied. The parents of these children filled out ATS-NHLI health questionnaires. The prevalence of reported respiratory symptoms and pulmonary diseases was found to be significantly higher among children growing up in the polluted community (Ashdod) as compared with the low-pollution area (Hadera). Logistic models fitted for the respiratory conditions which differed significantly between both areas of residence also included background variables that could be responsible for these differences. Relative risk values, which were calculated from the logistic models, were in the range of 1.47 for cough without cold to 2.66 for asthma for children from Ashdod, as compared with 1.00 for children from Hadera.

Air Pollutants↗

PubMed2001

The effects of lifestyle, dietary dairy intake and diabetes on bone density and vertebral deformity prevalence: the EVOS study.

The risk of low and moderate energy fracture is related to bone mineral density (BMD). Yet it is uncertain whether the epidemiologic determinants of fracture risk are the same as for low bone density. The European Vertebral Osteoporosis Study was a population-based prevalence study of vertebral deformity in 36 age-stratified population samples aged 50-80 years. In nearly 4000 subjects (13 centers), BMD measurements were also made at the spine, femoral neck and femoral trochanter. To investigate whether effects of reported physical activity on spine deformity risk were mediated through BMD, we modeled these and other risk factor data with BMD as the dependent variate after adjusting for age, center, sex and body mass index (BMI). The significant determinants of vertebral deformity risk were also entered into logistic models of deformity risk that included BMD measurements as covariates. Both current and lifetime physical activity were positively associated with BMD. This effect was stronger with hip BMD than with spine BMD. Lifetime smoking exposure was associated with reduced BMD. Type 2 diabetes mellitus was associated with increased BMD. Weak positive associations were found between consumption of dairy products and BMD at the three measured sites and these were strengthened by an interaction with measures of physical activity in men. Physical activity in women had the largest beneficial effect in lean women and in women exposed to hormone replacement therapy. When fracture risk was modeled with BMD as a covariate, the lifestyle and dietary determinants became less strongly related to vertebral deformity risk, suggesting that BMD may have acted as an intermediary variable. However, heavy physical activity in men still increased spine deformity risk after adjusting for BMD. It is concluded that physical activity in both genders and milk consumption in young women might protect against vertebral deformities in later life through their effects on bone density. The adverse effect of smoking on BMD was confirmed. Heavy physical activity in men might increase spine deformity risk even when BMD is normal.

Absorptiometry, Photon↗

PubMed1975

A double logistic comparison of growth patterns of normal children and children with Down's syndrome.

A double logistic model was used to compare six parameters of growth in standing height of 31 children with Down's syndrome with 136 children from the California Guidance Study. Multivariate analysis of variance of the growth data showed that while there were significant differences in all six parameters favouring the normal over the Down's children, there were no significant differences with respect to error of fit. Multivariate analysis with final height as a covariate revealed that differences between the normal and the Down's children in the prepubertal and adolescent components were explainable by differences in final height. In summary, the double logistic model, when applied to this sample of Down's children, identified those well defined logistic components which are characteristic of the growth of normal children, the differences being those of degree, not of form.

Analysis of Variance↗

PubMed2006

Diffusion kernel-based logistic regression models for protein function prediction.

Assigning functions to unknown proteins is one of the most important problems in proteomics. Several approaches have used protein-protein interaction data to predict protein functions. We previously developed a Markov random field (MRF) based method to infer a protein's functions using protein-protein interaction data and the functional annotations of its protein interaction partners. In the original model, only direct interactions were considered and each function was considered separately. In this study, we develop a new model which extends direct interactions to all neighboring proteins, and one function to multiple functions. The goal is to understand a protein's function based on information on all the neighboring proteins in the interaction network. We first developed a novel kernel logistic regression (KLR) method based on diffusion kernels for protein interaction networks. The diffusion kernels provide means to incorporate all neighbors of proteins in the network. Second, we identified a set of functions that are highly correlated with the function of interest, referred to as the correlated functions, using the chi-square test. Third, the correlated functions were incorporated into our new KLR model. Fourth, we extended our model by incorporating multiple biological data sources such as protein domains, protein complexes, and gene expressions by converting them into networks. We showed that the KLR approach of incorporating all protein neighbors significantly improved the accuracy of protein function predictions over the MRF model. The incorporation of multiple data sets also improved prediction accuracy. The prediction accuracy is comparable to another protein function classifier based on the support vector machine (SVM), using a diffusion kernel. The advantages of the KLR model include its simplicity as well as its ability to explore the contribution of neighbors to the functions of proteins of interest.

Databases, Protein↗

PubMed1998

Beta-2 microglobulin and lactate dehydrogenase levels are useful prognostic markers in early stage primary gastric lymphoma.

The optimal management of primary gastric lymphoma (PGL) remains undecided because a definitive classification for therapeutic decision is not available. The International Index Project has proved to be useful in patients with nodal disease, but in extranodal presentation it has not been tested. We reviewed 297 patients with early stage PGL. They were initially classified according to the prognostic features of the International Index Project. No influence on duration of time to treatment failure (TTF) or overall survival was observed. For this reason we developed a logistical model to identify prognostic factors in patients with early stage PGL. Levels of beta-2 microglobulin and lactic dehydrogenase were observed to have prognostic significance in both univariate and multivariate analysis. With these parameters we constructed a logistical model to identify patients at low risk (TTF = 76%; at 7 years overall survival was 96%), statistically different to patients at high risk (TTF = 34% and overall survival = 22%). The number of patients at intermediate risk were too small to compare with the other groups. Because pathological or other clinical or laboratory prognostic features cannot help in the identification of a prognostic model, we propose that the use beta-2 microglobulin and lactic dehydrogenase can define different groups at risk and develop a prognostic system to define the best therapeutic approach in this patients.

Adult↗

PubMed2001

[Can primary angioplasty result in the increase of the number of hemodynamics laboratories?].

Randomized studies comparing primary angioplasty with fibrinolysis have shown that mechanical intervention is superior to fibrinolytic treatment in terms of effective reperfusion, resulting in a decreased mortality rate and a lower incidence of reinfarction and recurrent ischemia. However, the effectiveness of a primary angioplasty strategy is strongly dependent on logistic models. Survey studies, and the GUSTO IIb trial have shown no clinical benefits of primary angioplasty over pharmacologic treatment in the "real world". Thus, a primary angioplasty program should be considered only if high performance technical and logistic models can be applied. These include surgical back-up, high volume cath lab, and an effective network of patient transportation, and as a consequence, the most cost/effective model may be identified in a tertiary referral center, and in the regionalization of the myocardial infarction centers.

Angioplasty↗

PubMedDate not supplied

Sleep, health and visual impairment in the elderly.

This study was undertaken in order to analyse the relationship between visual impairment and sleep in an elderly population. All 10?216 members of the pensioners' association in two Swedish counties were asked to participate in a questionnaire survey. The questionnaire included questions on civil status, the general state of health, the occurrence of somatic diseases and symptoms, sleep, medication and vision. 6143 evaluable questionnaires were received, of which 39.5% were from men. The mean (s.d.) ages of the male and female participants were 73.0 (6.0) and 72.6 (6.7) years, respectively. Visual impairment was reported by 20.9% of the men and 32.9% of the women. The proportion of visual impairment increased with age and was more common in women in each age group. Poor sleep occurred in 14.4% of the men and 27.9% of the women. Among subjects with visual impairment, poor sleep, frequent awakenings and difficulties to fall asleep after awakening at night were all more common in both men and women. In a multiple logistic regression analysis, significant independent correlates of poor night's sleep among the men were: visual impairment (odds ratio (OR) 1.3 95%, confidence interval (CI) 1.0-1.8) and poor health (OR 2.2, CI 1.6-3.0). Age, circulatory organ disease and diabetes were deleted by the logistic model. The significant independent correlates in women were: visual impairment (OR 1.6, CI 1.3-2.0) poor health (OR 2.6, CI 2.1-3.3) and circulatory organ diseases (OR 1.5 CI, 1.2-1.8). Age and diabetes were deleted by the logistic model. The results suggest that visual impairment could be an underestimated cause of sleep deterioration in the elderly.

Journal Article↗