SEARCH · PubMed Health

Results for “multiple linear regression”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,027 records · Page 57Linked to original sources

PubMed1984

Clinical, microbiological and immunological features associated with the treatment of active periodontosis lesions.

Clinical, microbiological and immunological factors were examined using data from a subject with periodontosis. The subject was monitored at bimonthly intervals for 26 months at 6 sites per tooth for redness, plaque, suppuration, bleeding on probing, pocket depth, and attachment level. Using attachment level measurements and the tolerance method of analysis, sites with active disease and control (inactive) sites of equal pocket depth were selected. Subgingival plaque samples were taken from these sites for predominant cultivable and dark field evaluation before, and 5 and 13 months after treatment by Widman flap surgery and systemic tetracycline. 50 isolates from each of 5 sites monitored before and after treatment were characterized and, if possible, identified. Active sites showed between 2 and 6 mm of attachment loss prior to therapy and "gained" between 2 and 9 mm of attachment after therapy. The control sites "gained" 0 to 1 mm of attachment after therapy. Bleeding on probing was significantly reduced after treatment, whereas plaque accumulation increased significantly in the sampled sites. Similar changes were seen in the remaining sites. The proportions of Actinobacillus actinomycetemcomitans and Selenomonas sputigena were elevated in active sites, while proportions of Bacteroides intermedius were elevated in control sites. 5 months after treatment, proportions of A. actinomycetemcomitans, S. sputigena and Eikenella corrodens were significantly decreased in the previously active sites and proportions of B. intermedius and E. corrodens were significantly decreased in the control sites. 13 months after therapy, the proportions of Fusobacterium nucleatum and Capnocytophaga species had increased. Multiple linear regression analysis was used to examine models which could "predict" the outcome, attachment level change in the previous monitoring period. The proportions of A. actinomycetemcomitans and S. sputigena, which were associated with destruction, coupled with the proportions of Streptococcus sanguis II and Campylobacter concisus which were associated with "gain" could predict prior attachment level change with an r2 of 0.93. Humoral antibody response to A. actinomycetemcomitans and C. sputigena significantly increased in a period in which multiple actively breaking down sites were detected. Antibody responses to 20 other species tested did not significantly change during the course of monitoring. Crevicular fluid and tissue levels of antibody to A. actinomycetemcomitans were elevated in 5 of 6 active destructive lesions prior to therapy.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

PubMed2001

Association between job strain and prevalence of hypertension: a cross sectional analysis in a Japanese working population with a wide range of occupations: the Jichi Medical School cohort study.

OBJECTIVES: To explore the association between the prevalence of hypertension in a Japanese working population and job strain (a combination of low control over work and high psychological demands), and to estimate this association in different sociodemographic strata. METHODS: From a multicentre community based cohort study of Japanese people, sex specific cross sectional analyses were performed on 3187 men and 3400 women under 65 years of age, all of whom were actively engaged in various occupations throughout Japan. The baseline period was 1992-95 [corrected]. The association between job characteristics--measured with a Japanese version of the Karasek demand-control questionnaire--and the prevalence of hypertension defined by blood pressure and from clinical diagnoses were examined. Adjustments were made for possible confounders. The analyses were repeated for stratified categories of occupational class, educational attainment, and age group. RESULTS: In men, the level of job strain (the ratio of psychological job demands to job control) correlated with the prevalence of hypertension. In a multiple logistic regression model, job strain was significantly related to hypertension (odds ratio 1.18; 95% confidence interval 1.05 to 1.32), after adjustment for age, employment (white collar v blue collar), marital status, family history of hypertension, cigarette smoking, alcohol intake, physical activity, and body mass index. The stratified analyses showed significant excess risks in the subordinate groups compared with managers, blue collar workers, less educated workers, and the older age groups. This association was not significant in women. Multiple linear regression analyses, with systolic and diastolic blood pressures as dependent variables, did not show any significant association. CONCLUSIONS: The findings provided limited proof that job strain is related to hypertension in Japanese working men. Older men in a lower social class may be more vulnerable to the hypertensive effects of job strain.

Adult↗

PubMed1992

Influx in vivo of low density, intermediate density, and very low density lipoproteins into aortic intimas of genetically hyperlipidemic rabbits. Roles of plasma concentrations, extent of aortic lesion, and lipoprotein particle size as determinants.

To compare the atherogenic potential of low density lipoprotein (LDL), intermediate density lipoprotein (IDL), and very low density lipoprotein (VLDL) under conditions where plasma levels of these lipoproteins are elevated, the influx of cholesterol in these lipoproteins into the aortic intima was measured in vivo in genetically hyperlipidemic rabbits from the St. Thomas's Hospital strain, an animal model that shares many of the features of the human disorder familial combined hyperlipidemia. Univariate linear regression showed that the arterial influx of LDL cholesterol (n = 25), IDL cholesterol (n = 14), and VLDL cholesterol (n = 10) was positively and linearly associated with plasma concentrations of LDL cholesterol in the range 0.2-6.4 mmol/l, of IDL cholesterol in the range 0.1-7.0 mmol/l, and of VLDL cholesterol in the range 0.7-8.5 mmol/l, respectively, and also with the extent of lesions in the arterial intima in the range 0-100% of the surface area. Multiple linear regression suggested that the arterial influx of LDL, IDL, and VLDL cholesterol was linearly dependent on plasma concentration, independent of lesion size. Furthermore, it appeared that the arterial influx of the three lipoproteins was linearly dependent on the extent of the lesions, independent of lipoprotein concentration. When influx was normalized for plasma concentration (intimal clearance) and for lesion size (compared within the same aorta), the intimal clearance of the larger IDL and VLDL particles was 15-35% less than that of the smaller LDL particles. These findings suggest that the quantitatively most important mechanism for transfer of plasma lipoproteins into the arterial intima involves nonspecific molecular sieving and that at elevated plasma levels, IDL and VLDL share with LDL the potential for causing atherosclerosis.

Animals↗

PubMed1997

Growth hormone (GH) provocative retesting of 108 young adults with childhood-onset GH deficiency and the diagnostic value of insulin-like growth factor I (IGF-I) and IGF-binding protein-3.

Serum levels of total insulin-like growth factor I (IGF-I) and IGF-binding protein-3 (IGFBP-3) reflect the endogenous GH secretion in healthy children and exhibit little diurnal variation, which makes them good diagnostic markers for screening of GH deficiency (GHD) in short children, although some controversy still exists. In adults, the diagnostic value of IGF-I and IGFBP-3 suspected of GHD has been reported in only a few studies. We performed a GH provocative test, using oral clonidine, in 108 patients who had previously been treated with GH during childhood (73 men and 35 women). Basal IGF-I and IGFBP-3 levels were compared to those in 1237 healthy controls (312 controls > 18 yr) as well as to peak GH levels. Seventy-nine patients had peak GH values below a cut-off value of 7.5 micrograms/L (34 with isolated GHD), whereas 29 patients had a normal GH response (28 with previous isolated GHD), i.e. 45% of patients treated with GH during childhood because of isolated GHD had a normal GH response when retested in adulthood. Multiple regression analysis revealed that peak GH levels were dependent on the degree of hypopituitarism, body mass index, and duration of disease. IGF-I levels were below -2 SD in 60 of 79 GHD patients and above -2 SD in 21 of 29 patients with a normal GH response. IGFBP-3 levels were below -2 SD in 54 of 79 GHD patients and above -2 SD in 23 of 29 patients with a normal GH response. Multiple linear regression analysis demonstrated that IGF-I and IGFBP-3 were significantly dependent on peak GH levels and the number of other pituitary axes affected. In this analysis, duration of disease was significantly associated with both IGF-I and IGFBP-3, whereas body mass index was significantly associated with IGFBP-3, but not with IGF-I. We conclude that IGF-I and IGFBP-3 determinations predict the outcome of a GH provocative test in adults suspected of GHD and believe that IGF-I as well as IGFBP-3 serum concentrations are valuable diagnostic parameters in the evaluation of GHD in adults with childhood-onset disease. We suggest that children who have been treated with GH should undergo reassessment of their GH secretory status as young adults by provocative testing as well as by IGF-related peptides before continued adult GH replacement therapy is considered. However, our data suggest that it is not necessary to reconfirm GH deficiency by GH provocative testing in young adults who have two or more pituitary hormone deficiencies in addition to GHD.

Administration, Oral↗

PubMed2005

Evaluation of serum enzyme activities as predictors of passive transfer status in lambs.

OBJECTIVE: To determine the associations between serum IgG concentration and serum activities of gamma-glutamyltransferase (GGT), alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, and pseudocholinesterase for the potential use of these serum enzymes as predictors of passive transfer status in neonatal lambs. DESIGN: Prospective observational study. ANIMALS: 47 Sardinian lambs from birth to 2 days old. PROCEDURE: Serum enzyme activities were measured by use of commercially available kits and a clinical biochemical analyzer. Serum IgG concentration was determined by single radial immunodiffusion. Associations between serum IgG concentration and the activity of each serum enzyme were established by use of regression analysis. RESULTS: A significant correlation was detected between serum IgG concentration and serum GGT activity in 1- and 2-day-old lambs. Minimal correlations were detected between serum IgG concentration and serum alkaline phosphatase activity in 1-day-old lambs and serum pseudocholinesterase activity in 1- and 2-day-old lambs. No significant associations were detected between serum IgG concentration and serum activities of aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase. A multiple linear regression model was accurate for the estimation of the natural logarithm of serum IgG concentration as a function of the natural logarithm of serum GGT activity and of the age of lambs at the time of sampling (adjusted R2 = 0.89). This model was then used to calculate the serum GGT activity equivalent to various serum IgG concentrations for 1- and 2-day-old lambs. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that passive transfer status in neonatal lambs can be successfully predicted by measurement of serum GGT activity but not by measurement of the other enzymes tested.

Alanine Transaminase↗

PubMed2006

QSPR study of polychlorinated diphenyl ethers by molecular electronegativity distance vector (MEDV-4).

Polychlorinated diphenyl ethers (PCDEs) have received more and more concerns as a group of ubiquitous potential persistent organic pollutants (POPs). By using molecular electronegativity distance vector (MEDV-4), multiple linear regression (MLR) models are developed for sub-cooled liquid vapor pressures (P(L)), n-octanol/water partition coefficients (K(OW)) and sub-cooled liquid water solubilities (S(W,L)) of 209 PCDEs and diphenyl ether. The correlation coefficients (R) and the leave-one-out cross-validation (LOO) correlation coefficients (R(CV)) of all the 6-descriptor models for logP(L), logK(OW) and logS(W,L) are more than 0.98. By using stepwise multiple regression (SMR), the descriptors are selected and the resulting models are 5-descriptor model for logP(L), 4-descriptor model for logK(OW), and 6-descriptor model for logS(W,L), respectively. All these models exhibit excellent estimate capabilities for internal sample set and good predictive capabilities for external samples set. The consistency between observed and estimated/predicted values for logP(L) is the best (R=0.996, R(CV)=0.996), followed by logK(OW) (R=0.992, R(CV)=0.992) and logS(W,L) (R=0.983, R(CV)=0.980). By using MEDV-4 descriptors, the QSPR models can be used for prediction and the model predictions can hence extend the current database of experimental values.

Halogenated Diphenyl Ethers↗

PubMed1999

Relationship between serum glucose and injury severity score in childhood trauma.

PURPOSE: The aim of this study was to examine the relationship between initial serum glucose and injury severity score (ISS) in children with multiple trauma. METHODS: Charts from all patients 0 to 19 years of age admitted to a children's hospital in 1995 with acute multiple trauma were reviewed. Data collected included initial serum glucose level, heart rate (HR), systolic blood pressure (SBP), Injury Severity Score (ISS), age, gender, location of trauma, and need for intravenous fluids or epinephrine. Data were analyzed using multiple linear regression. RESULTS: A total of 185 charts were reviewed. The mean ISS was 11.3; the mean glucose was 162.8 mg/dL. After adjusting for age, gender, HR, SBP, and administration of epinephrine or fluid bolus, a significant direct relationship between serum glucose and ISS was found (r = 0.52, P < .01). A stronger relationship was found in children less than 2 years old (r = 0.60, P = .04). CONCLUSIONS: A significant direct relationship exists between glucose and ISS in children with multiple trauma. High glucose values may indicate more severe injury, especially in children less than 2 years old.

Adolescent↗

PubMed2002

Analysis and predictive models of stormwater runoff volumes, loads, and pollutant concentrations from watersheds in the Twin Cities metropolitan area, Minnesota, USA.

Urban nonpoint source pollution is a significant contributor to water quality degradation. Watershed planners need to be able to estimate nonpoint source loads to lakes and streams if they are to plan effective management strategies. To meet this need for the twin cities metropolitan area, a large database of urban and suburban runoff data was compiled. Stormwater runoff loads and concentrations of 10 common constituents (six N and P forms, TSS, VSS, COD, Pb) were characterized, and effects of season and land use were analyzed. Relationships between runoff variables and storm and watershed characteristics were examined. The best regression equation to predict runoff volume for rain events was based on rainfall amount, drainage area, and percent impervious area (R2 = 0.78). Median event-mean concentrations (EMCs) tended to be higher in snowmelt runoff than in rainfall runoff, and significant seasonal differences were found in yields (kg/ha) and EMCs for most constituents. Simple correlations between explanatory variables and stormwater loads and EMCs were weak. Rainfall amount and intensity and drainage area were the most important variables in multiple linear regression models to predict event loads, but uncertainty was high in models developed with the pooled data set. The most accurate models for EMCs generally were found when sites were grouped according to common land use and size.

Forecasting↗

PubMed2006

[Factors influencing pulmonary function in Tunisian women aged 45 years and more].

INTRODUCTION: The aim of this study was to analyse the factors influencing pulmonary function and inspiratory muscle strength in healthy Tunisian women aged >or=45 years and in particular to determine the effect of parity. METHODS: A medical questionnaire together with an evaluation of sporting activity score and 2 levels for schooling and socio-economic status was administered. Parity was introduced as numeric, as dichotomous (G1: or=4) and in 3 classes (C1:<2; C2:=3-4; C3: > 4). Plethysmography with measurement of airway conductance and maximal inspiratory pressure was performed. RESULTS: 108 women were included. According to the ascending multiple linear regression, and in decreasing order, the following influencing factors are noted: Age and height, parity, weight and daily activity, schooling level, and finally leisure activity, body mass index, and physical activity. With high parity, and especially in women aged >or=60 years, there was a decrease in inspiratory muscle strength and an obstructive tendency, without associated restrictive component. Parity effects are age independent. CONCLUSIONS: Factors influencing the pulmonary function of healthy Tunisian women aged >or=45 years are multiple. Lung function declines with increasing parity.

Age Factors↗

PubMed1998

Epidermal iontophoresis: II. Application of the ionic mobility-pore model to the transport of local anesthetics.

PURPOSE: An in vitro study was carried out to determine the iontophoretic permeability of local anesthetics through human epidermis. The relationship between physicochemical structure and the permeability of these solutes was then examined using an ionic mobility-pore model developed to define quantitative relationships. METHODS: The iontophoretic permeability of both ester-type anesthetics (procaine, butacaine, tetracaine) and amide-type anesthetics (prilocaine, mepivacaine, lidocaine, bupivacaine, etidocaine, cinchocaine) were determined through excised human epidermis over 2 hrs using a constant d.c. current and Ag/AgCl electrodes. Individual ion mobilities were determined from conductivity measurements in aqueous solutions. Multiple stepwise regression was applied to interrelate the iontophoretic permeability of the solutes with their physical properties to examine the appropriateness of the ionic mobility-pore model and to determine the best predictor of iontophoretic permeability of the local anesthetics. RESULTS: The logarithm of the iontophoretic permeability coefficient (log PC(j,iont)) for local anesthetics was directly related to the log ionic mobility and MW for the free volume form of the model when other conditions are held constant. Multiple linear regressions confirmed that log PC(j,iont) was best defined by ionic mobility (and its determinants: conductivity, pKa and MW) and MW. CONCLUSIONS: Our results suggest that of the properties studied, the best predictors of iontophoretic transport of local anesthetics are ionic mobility (or pKa) and molecular size. These predictions are consistent with the ionic mobility pore model determined by the mobility of ions in the aqueous solution, the total current, epidermal permselectivity and other factors as defined by the model.

Anesthetics, Local↗

PubMed2005

Genetic determinants of plasma HDL-cholesterol levels in familial hypercholesterolemia.

The objective of this study was to determine the extent to which common genetic variants can explain the variation of high-density lipoprotein cholesterol (HDL-C) plasma levels in familial hypercholesterolemia (FH). FH is characterized by elevated low-density lipoprotein cholesterol levels and premature cardiovascular disease (CVD). Although low HDL-C levels have been shown to affect the severity of the clinical phenotype, little is known about the factors that determine HDL-C levels in these patients. A cohort of 1002 heterozygous FH patients was genotyped for polymorphisms in the genes encoding for ATP-binding cassette transporter A1, apolipoprotein (apo) AIV, apoCIII, apoE, cholesteryl transfer ester protein, hepatic lipase, lipoprotein lipase, and two paraoxonases. Multiple linear regression showed that, together, these polymorphisms explain only 3.9% of the variation of HDL-C plasma levels. When significant two-way interactions between the polymorphisms were also taken into account, the explained variation rose to 12.5%. In a regression model that also incorporated sex, smoking, alcohol use, body mass index, and concomitant beta-blocker use as covariates, the explained variation of HDL-C plasma levels even increased to 32.5%. This study provides direct evidence that multiple, modestly penetrant, but highly prevalent, polymorphisms can explain a substantial part of the variation of HDL-C plasma levels in a representative large cohort of heterozygous FH patients.

ATP Binding Cassette Transporter 1↗

PubMed2006

Characteristics of early transient, persistent, and late onset wheezers at 9 to 11 years of age.

STUDY OBJECTIVE: To investigate the early determinants and characteristics of different phenotypes of wheeze in children on the basis of questionnaire data, lung function, and prick tests. DESIGN: Cross-sectional survey. Setting. Rome and Fiumicino municipalities in Lazio region, Italy, within the ISAAC phase II project. SUBJECTS: Sample of 2107 9-11 year old schoolchildren (response rate 83.5%). RESULTS: We divided children into four mutually exclusive groups according to onset of wheeze: 154 early transient (birth to age 2), 51 persistent (birth to age 2 and current), 66 late onset (current only), and 1,446 control subjects (no early or current wheeze). Logistic regression models have shown that a family history of asthma and allergies is strongly associated with persistent and late onset wheezing; exposure to parental smoking--both during pregnancy and during the child's first year of life--is related to persistent wheezing; all children with wheezing show a significantly greater risk to have current respiratory symptoms other than wheeze compared with control subjects; current allergic rhinoconjunctivitis symptoms and atopy are related with both persistent and late onset wheeze. Multiple linear regression models show that forced expiratory rates at 25% to 75% of vital capacity (FEF25-75) and the ratio between forced expiratory volume in 1 second and forced vital capacity (FEV1/FVC) are significantly lower both in early transient (-305 mL/s, -1.7%) and persistent (-298 mL/s, -3.2%) wheezers; FEV1/FVC is significantly reduced in late onset wheezers too (-2.0%). CONCLUSIONS: The strength of the association of family history and exposure to parental smoking varies with the three wheezing phenotypes. Moreover, early, persistent and late onset wheezers have different clinical characteristics in terms of their respiratory health and atopic status.

Age Factors↗

PubMed2002

Factors affecting health related quality of life of patients with inflammatory bowel disease.

UNLABELLED: Using a disease specific instrument to measure the health related quality of life (HRQOL) of patients with inflammatory bowel disease (IBD), it has been shown that their perceived HRQOL worsens during active disease. The precise factors involved in HRQOL changes reported by these patients are largely unknown. Our aim was to elucidate which socio-demographic and health status variables are related with HRQOL in IBD patients. To this end, 354 patients with IBD were interviewed. To quantify the impairment in the HRQOL, the 36-item version of the inflammatory bowel disease questionnaire (IBDQ) was administered to all patients. To explore the relation of each individual variable on the HRQOL an univariate analysis by using the Spearman correlation, the Mann-Whitney or the Kruskal-Wallis test was performed when necessary. Factors significant at the univariate analysis were assessed using multiple linear regression modeling with global IBDQ score as the dependent factor. RESULTS: Disease type did not predict IBDQ score in the univariate nor in the multivariate analysis. Consequently, statistical analysis was performed in the global group of 354 patients independently of the type of disease. Lower recurrence/year index, longer disease duration, higher level of education, symptom activity, male gender and non-necessity of hospitalization all predict a better HRQOL (p < 0.05). Factors which remained significant (p < 0.05) in the multiple regression modeling were gender, need of hospitalization, symptomatic activity, recurrence/year index and education level. CONCLUSIONS: Symptomatic activity and socio-demographic variables such as gender and education are the most important factors involved in the impairment of HRQOL in patients with IBD.

Adult↗

PubMed2000

Breast-feeding and weight change in newborns in Jamaica.

This study was conducted to examine weight change of exclusively breast-fed infants during the first week and through the first 24 days of life, and to evaluate the effect of breast-feeding factors and maternal characteristics on early weight change in the infants. The weights of 21 infants were recorded on day 1 (day of birth), and on days 3, 7, 10, 17, and 24, and the data analysed to evaluate weight change over the period. Multiple regression analysis was used to assess whether birth weight as well as maternal and breast-feeding factors were significant predictors of weight on day 24. Nineteen of the 21 infants gained weight between days 1 and 3, and 20 infants gained weight between days 3 and 7. All infants gained weight over the 24-day period and their weights at day 7 and day 24 were significantly different (P < 0.05 and P < 0.01, respectively) from their birth weights. Multiple linear regression analysis showed that significant (P < 0.01) predictors of weight gain by day 24 included birth weight, mother's educational level, whether the baby cried before feeding, and length of feeding time periods. This is the first study of weight change in the early days and weeks of life of exclusively breast-fed newborn infants in Jamaica. The infants showed significant weight gain during the study period and weight gain was affected by certain maternal and breast-feeding factors.

Adult↗

PubMed1997

Physical activity, sports participation, and risk factors in adolescents.

The purpose of this study was to analyze the relationships between physical activity (ACT), including sports participation (SP) and antecedent risk factors for coronary heart disease (CHD), in a representative sample of adolescents from Northern Ireland, a region of high coronary mortality. Biological and behavioral risk factors were measured in a random sample of 1015 school children aged 12 and 15 yr. ACT and SP were assessed by self-report questionnaire, and relationships with biological risk factors were analyzed with stepwise multiple linear regression after controlling for potential confounders. Results showed that in 15-yr-old males ACT was beneficially associated with systolic blood pressure (P < 0.05), lipid profile, and cardiorespiratory fitness (both P < 0.01). In 15-yr-old females, SP was associated beneficially with fatness and cardiorespiratory fitness. Odds ratios calculated from logistic regression revealed that for the older children, a relatively small drop (-20%) in ACT (boys) or SP (girls) was significantly related to the probability of exposure to multiple risk factors. Overall, relationships were stronger for males rather than females and for older rather than younger children. This study provides further evidence for beneficial associations between ACT, SP, and CHD risk status in adolescents.

Adolescent↗

PubMed1991

Further investigations on protein requirement of genetically lean and fat chickens.

1. Genetically lean (LL) or fat (FL) chickens were fed from 28 to 42 d of age on one of 6 diets with different protein contents (from 73 to 208 g/kg). In order to keep a constant amino acid balance the experimental diets were made by diluting a well-balanced protein-rich diet with a protein-free diet. 2. Dietary protein influenced the growth rate of both genotypes similarly. However, maximum weight gain was reached in LL at a lower protein intake than in FL. 3. Regression between total protein gain (body protein + feather protein) or body protein gain and protein intake exhibited significantly different slopes, that of LL being superior to that of FL. 4. At a given protein intake, feather protein gain was also superior in LL to FL. Moreover feather protein, as a percentage of total protein gain, was superior in LL to FL. When the dietary protein fell below 126 g/kg, feather protein represented a higher proportion of total protein gain. 5. Multiple linear regressions of protein intake (as the dependent variable), and body weight and protein gain or weight gain (as the independent variables) suggest that the maintenance requirement for protein is similar in both lines but that the protein efficiency for growth is significantly superior in LL. 6. In a second experiment both genotypes were offered either a single high protein diet (232 g/kg) or a single medium protein diet (186 g/kg) or had free-choice between a high (269 g/kg) and a low protein (145 g/kg) diet. In free-choice feeding, FL chickens selected an overall dietary protein content which was significantly lower (179 v. 200 g/kg) to that of LL. In both genotypes, free-choice feeding led to fatter and less efficient chickens than predicted by the linear regression between adiposity or food conversion and protein content.

Amino Acids↗

PubMed2006

Residential segregation and injection drug use prevalence among Black adults in US metropolitan areas.

OBJECTIVES: We analyzed the relations of two 1990 dimensions of racial residential segregation (isolation and concentration) with 1998 injection drug use prevalence among Black adult residents of 93 large US metropolitan statistical areas (MSAs). METHODS: We estimated injection drug use prevalence among Black adults in each MSA by analyzing 3 databases documenting injection drug users' encounters with the health care system. Multiple linear regression methods were used to investigate the relationship of isolation and concentration to the natural logarithm of Black adult injection drug use prevalence, controlling for possible confounders. RESULTS: The median injection drug use prevalence was 1983 per 100000 Black adults (interquartile range: 1422 to 2759 per 100000). The median isolation index was 0.48 (range: 0.05 to 0.84): in half the MSAs studied, the average Black resident inhabited a census tract where 48% or more of the residents were Black. The multiple regression model indicates that an increase of 0.50 in the isolation index was associated with a 23% increase in injection drug use prevalence among Black adults. Concentration was unrelated to the outcome. CONCLUSIONS: Residential isolation is positively related to Black injection drug use prevalence in MSAs. Research into the pathways linking isolation to injection drug use is needed.

Adult↗

PubMed2006

Relationships between serum hormone levels and semen quality among men from an infertility clinic.

Participation rates in epidemiologic studies on semen quality are generally very low, raising concerns as to the potential for selection bias. Since hormones both initiate and maintain spermatogenesis, they may serve as surrogates of semen quality in epidemiologic studies. For this reason, in the present study, we explored the influence and predictive ability of reproductive and thyroid hormones on semen quality among men who were partners in an infertile couple. Between 1999 and 2003, 388 men were recruited from Massachusetts General Hospital Andrology Laboratory for clinical evaluation of fertility status. Fresh semen samples were assessed for quality (concentration, motility and morphology) and the serum levels of hormones, including follicle-stimulating hormone (FSH), luteinizing hormone (LH), inhibin B, sex hormone-binding globulin (SHBG), testosterone, free androgen index, free T4, total T3, and thyroid-stimulating hormone (TSH), were measured. Multiple logistic regression revealed increased odds for below-reference sperm concentration and morphology in men with increased FSH, and decreased odds for below-reference sperm concentration and motility in men with increased inhibin B. When FSH and inhibin B were divided into quintiles, the relationships with sperm concentration showed evidence of a threshold value. However, the ability of specific FSH (10 IU/L) and/or inhibin B (80 pg/mL) cutoff values to predict semen quality was lower than in previous reports. In multiple linear regression analysis, FSH and LH were inversely associated with sperm concentration, motility, and morphology. Inhibin B and free T4 were positively associated with sperm concentration, while there was a suggestive positive association between testosterone and sperm motility. In conclusion, we have found that FSH, LH, inhibin B, testosterone and free T4 levels are associated with human semen parameters. Additional consideration should be given to the utility of serum hormone levels as a surrogate for semen quality in epidemiologic studies in which the collection of semen is difficult due to logistical and/or volunteer rate constraints.

Adolescent↗