Comparing the activPAL software's Primary Time in Bed Algorithm against Self-Report and van der Berg's Algorithm

The purpose of this study was to compare activPAL algorithm-estimated values for time in bed (TIB), wake time (WT) and bedtime (BT) against self-report and an algorithm developed by van der Berg and colleagues. Secondary analyses of baseline data from the Community Activity for Prevention Study (CAPS) were used in which adults ≥ 18 years wore the activPAL for seven days. Mixed-effects models compared differences between TIB, WT, and BT for all three methods. Bland-Altman plots examined agreement and the two-one-sided test examined equivalence. activPAL was not equivalent to self-report or van der Berg in estimating TIB, but was equivalent to self-report for estimating BT, and was equivalent to van der Berg for estimating WT. The activPAL algorithm requires adjustments before researchers can use it to estimate TIB. However, researchers can use activPAL's option to manually enter self-reported BT and WT to estimate TIB and better understand 24-hour movement patterns.

Rationale and design for the community activation for prevention study (CAPs): A randomized controlled trial of community gardening

BACKGROUND

Engaging in health-promoting behaviors (e.g., healthy fruit- and vegetable-rich diet, physical activity) and living in supportive social and built environments are consistently and significantly associated with reductions in cancer, heart disease, diabetes, and other chronic diseases. Interventions to change diet and physical activity behaviors should aim to educate individuals, change the environments in which people live, work and recreate, improve access, availability, and affordability of healthy foods, and create safe places the facilitate active lifestyles. This trial will assess whether community gardening increases fruit and vegetable consumption and physical activity, improves social support and mental health, and reduces age-associated weight gain and sedentary time among a multi-ethnic, mixed-income population.

METHODS/DESIGN

A randomized controlled trial of community gardening began in Denver, Colorado in January 2017. Over 3 years, we will recruit 312 consenting participants on Denver Urban Gardens' waitlists and randomize them to garden or remain on the waitlist. At baseline (pre-gardening), harvest time, and post-intervention, study participants will complete three 24-hour dietary recalls, a 7-day activity monitoring period using accelerometry, a health interview and physical anthropometry.

DISCUSSION

This project addresses health-promoting behaviors among a multi-ethnic, mixed-income adult population in a large metropolitan area. If successful, this trial will provide evidence that community gardening supports and sustains healthy and active lifestyles, which can reduce risk of cancer and other chronic diseases.

TRIAL REGISTRATION

ClinicalTrials.gov, ID: NCT03089177: Registered on 03/17/17.

Exploring residual risk for diabetes and microvascular disease in the Diabetes Prevention Program Outcomes Study (DPPOS)

AIM

Approximately half of the participants in the Diabetes Prevention Outcomes Study (DPPOS) had diabetes after 15 years of follow-up, whereas nearly all the others remained with pre-diabetes. We examined whether formerly unexplored factors in the DPPOS coexisted with known risk factors that posed additional risk for, or protection from, diabetes as well as microvascular disease.

METHODS

Cox proportional hazard models were used to examine predictors of diabetes. Sequential modelling procedures considered known and formerly unexplored factors. We also constructed models to determine whether the same unexplored factors that associated with progression to diabetes also predicted the prevalence of microvascular disease. Hazard ratios (HR) are per standard deviation change in the variable.

RESULTS

In models adjusted for demographics and known diabetes risk factors, two formerly unknown factors were associated with risk for both diabetes and microvascular disease: number of medications taken (HR = 1.07, 95% confidence intervals (95% CI) 1.03 to 1.12 for diabetes; odds ratio (OR) = 1.10, 95% CI 1.04 to 1.16 for microvascular disease) and variability in HbA_1c (HR = 1.02, 95% CI 1.01 to 1.03 for diabetes; OR = 1.06, 95% CI 1.04 to 1.09 for microvascular disease per sd). Total comorbidities increased risk for diabetes (HR = 1.10, 95% CI 1.04 to 1.16), whereas higher systolic (OR = 1.22, 95% CI 1.13 to 1.31) and diastolic (OR = 1.14, 95% CI 1.05 to 1.22) blood pressure, as well as the use of anti-hypertensives (OR = 1.41, 95% CI 1.23 to 1.62), increased risk of microvascular disease.

CONCLUSIONS

Several formerly unexplored factors in the DPPOS predicted additional risk for diabetes and/or microvascular disease - particularly hypertension and the use of anti-hypertensive medications - helping to explain some of the residual disease risk in participants of the DPPOS.

Diabetes autoantibodies do not predict progression to diabetes in adults: the Diabetes Prevention Program

AIMS

To determine if the presence of diabetes autoantibodies predicts the development of diabetes among participants in the Diabetes Prevention Program.

METHODS

A total of 3050 participants were randomized into three treatment groups: intensive lifestyle intervention, metformin and placebo. Glutamic acid decarboxylase (GAD) 65 autoantibodies and insulinoma-associated-2 autoantibodies were measured at baseline and participants were followed for 3.2 years for the development of diabetes.

RESULTS

The overall prevalence of GAD autoantibodies was 4.0%, and it varied across racial/ethnic groups from 2.4% among Asian-Pacific Islanders to 7.0% among non-Hispanic black people. There were no significant differences in BMI or metabolic variables (glucose, insulin, HbA(1c), estimated insulin resistance, corrected insulin response) stratified by baseline GAD antibody status. GAD autoantibody positivity did not predict diabetes overall (adjusted hazard ratio 0.98; 95% CI 0.56-1.73) or in any of the three treatment groups. Insulinoma-associated-2 autoantibodies were positive in only one participant (0.033%).

CONCLUSIONS

These data suggest that 'diabetes autoimmunity', as reflected by GAD antibodies and insulinoma-associated-2 autoantibodies, in middle-aged individuals at risk for diabetes is not a clinically relevant risk factor for progression to diabetes.

Development and validation of an ankle brachial index risk model for the prediction of cardiovascular events

BACKGROUND

The ankle brachial index (ABI) is related to risk of cardiovascular events independent of the Framingham risk score (FRS). The aim of this study was to develop and evaluate a risk model for cardiovascular events incorporating the ABI and FRS.

DESIGN

An analysis of participant data from 18 cohorts in which 24,375 men and 20,377 women free of coronary heart disease had ABI measured and were followed up for events.

METHODS

Subjects were divided into a development and internal validation dataset and an external validation dataset. Two models, comprising FRS and FRS + ABI, were fitted for the primary outcome of major coronary events.

RESULTS

In predicting events in the external validation dataset, C-index for the FRS was 0.672 (95% CI 0.599 to 0.737) in men and 0.578 (95% CI 0.492 to 0.661) in women. The FRS + ABI led to a small increase in C-index in men to 0.685 (95% CI 0.612 to 0.749) and large increase in women to 0.690 (95% CI 0.605 to 0.764) with net reclassification improvement (NRI) of 4.3% (95% CI 0.0 to 7.6%, p = 0.050) and 9.6% (95% CI 6.1 to 16.4%, p < 0.001), respectively. Restricting the FRS + ABI model to those with FRS intermediate 10-year risk of 10 to 19% resulted in higher NRI of 15.9% (95% CI 6.1 to 20.6%, p < 0.001) in men and 23.3% (95% CI 13.8 to 62.5%, p = 0.002) in women. However, incorporating ABI in an improved newly fitted risk factor model had a nonsignificant effect: NRI 2.0% (95% CI 2.3 to 4.2%, p = 0.567) in men and 1.1% (95% CI 1.9 to 4.0%, p = 0.483) in women.

CONCLUSIONS

An ABI risk model may improve prediction especially in individuals at intermediate risk and when performance of the base risk factor model is modest.

Glucose control predicts 2-year change in lipid profile in youth with type 1 diabetes

OBJECTIVE

To test the hypothesis that a change in glycated hemoglobin (A1c) over a follow-up interval of approximately 2 years would be associated with concomitant changes in fasting lipids in individuals with type 1 diabetes (T1D).

STUDY DESIGN

All subjects with T1D diagnosed in 2002-2005 in the SEARCH for Diabetes in Youth study with at least 2 study visits ∼12 and ∼24 months after an initial visit were included (age at initial visit, 10.6 ± 4.1 years; 48% female; diabetes duration, 10 ± 7 months; 76% non-Hispanic white; A1c = 7.7% ± 1.4%). Longitudinal mixed models were fit to examine the relationship between change in A1c and change in lipid levels (total cholesterol [TC], high-density lipoprotein-cholesterol [HDL-c], low-density lipoprotein-cholesterol [LDL-c], log triglycerides [TG], and non-HDL-c) with adjustment for possible confounders.

RESULTS

Change in A1c over time was significantly associated with changes in TC, HDL-c, LDL-c, TG, and non-HDL-c over the range of A1c values. For example, for a person with an A1c of 10% and then a 2% decrease in A1c 2 years later (to 8%), the model predicted concomitant changes in TC (-0.29 mmol/L, -11.4 mg/dL), HDL-c (0.03 mmol/L, 1.3 mg/dL), LDL-c (-0.23 mmol/L, -9.0 mg/dL), and non-HDL-c (-0.32 mmol/L, -12.4 mg/dL) and an 8.5% decrease in TG (mmol/L).

CONCLUSIONS

Improved glucose control over a 2-year follow-up was associated with a more favorable lipid profile but may be insufficient to normalize lipids in dyslipidemic T1D youth needing to decrease lipids to goal.

Clinical evolution of beta cell function in youth with diabetes: the SEARCH for Diabetes in Youth study

AIMS/HYPOTHESIS

Few studies have explored the epidemiology of beta cell loss in youth with diabetes. This report describes the evolution and major determinants of beta cell function, assessed by fasting C-peptide (FCP), in the SEARCH for Diabetes in Youth study.

METHODS

Participants were 1,277 youth with diabetes (948 positive for diabetes autoantibodies [DAs] and 329 negative for DAs), diagnosed when aged <20 years, who were followed from a median of 8 months post diagnosis, for approximately 30 months. We modelled the relationship between rate of change in log FCP and determinants of interest using repeated measures general linear models.

RESULTS

Among DA-positive youth, there was a progressive decline in beta cell function of 4% per month, independent of demographics (age, sex, race/ethnicity), genetic susceptibility to autoimmunity (HLA risk), HbA(1c) and BMI z score, or presence of insulin resistance. Among DA-negative youth, there was marked heterogeneity in beta cell loss, reflecting an aetiologically mixed group. This group likely includes youths with undetected autoimmunity (whose decline is similar to that of DA-positive youth) and youth with non-autoimmune, insulin-resistant diabetes, with limited decline (~0.7% per month).

CONCLUSIONS/INTERPRETATION

SEARCH provides unique estimates of beta cell function decline in a large sample of youth with diabetes, indicating that autoimmunity is the major contributor. These data contribute to a better understanding of clinical evolution of beta cell function in youth with diabetes, provide strong support for the aetiological classification of diabetes type and may inform tertiary prevention efforts targeted at high-risk groups.

Association testing of TCF7L2 polymorphisms with type 2 diabetes in multi-ethnic youth

AIM/HYPOTHESIS

Common variants in the transcription factor 7-like 2 (TCF7L2) gene have been associated with type 2 diabetes in adults. However, it is not known whether TCF7L2 variation increases the risk of early onset type 2 diabetes. Using a case-control design, we examined whether the reported variants [rs12255372 (T/G) and rs7903146 (T/C)] are associated with type 2 diabetes in SEARCH for Diabetes in Youth study participants.

METHODS

Variants were genotyped in 694 non-Hispanic white (NHW) youth (86 cases, mean age 15.5 years, mean BMI 34.8; and 608 controls, mean age 14.4 years, mean BMI 22.3) and 545 African-American (AA) youth (154 cases, mean age 15.9, mean BMI 37; and 391 controls, mean age 14.8, mean BMI 23.8). Logistic regression adjusted for age, sex, BMI and West African ancestry.

RESULTS

The association of the risk T allele with case/control status was different in AA and NHW youth (p = 0.025). Among AA youth, each copy of the T allele (rs7903146) was associated with a 1.97-fold (1.37, 2.82) increased odds for type 2 diabetes (p < 0.0001), after adjustment for age, sex, BMI and African ancestry. No significant association was detected in NHW youth (adjusted OR, 1.14; 0.73, 1.79).

CONCLUSION/INTERPRETATION

TCF7L2 variation is associated with an increased risk of early-onset type 2 diabetes among AA youth, and the association appears to be stronger in AA than NHW youth. This suggests potential different contributions of genetic and environmental factors to early-onset type 2 diabetes by race.

Association of insulin sensitivity to lipids across the lifespan in people with Type 1 diabetes

AIMS

Insulin resistance and dyslipidaemia both increase cardiovascular risk in Type 1 diabetes. However, little data exist on the associations of insulin resistance to lipids in Type 1 diabetes. Our objective was to explore the associations between insulin resistance (assessed by glucose infusion rate) and lipids in people with Type 1 diabetes and determine whether adiposity and/or average glycaemia influence these associations.

METHODS

Hyperinsulinaemic-euglycaemic clamp studies were performed in 60 subjects with Type 1 diabetes aged 12-19 years (age 15±2 years, 57% female, duration of diabetes 6.3±3.8 years, HbA(1c) 8.6±1.5%, IFCC=70 mmol/mol) and 40 subjects with Type 1 diabetes aged 27-61 years (age 45±9 years, 53% female, duration of diabetes 23±8 years, HbA(1c) 7.5±0.9%, IFCC=58 mmol/mol). Multiple linear regression models were fit to examine the association between glucose infusion rate and fasting lipid levels with adjustment for possible confounders.

RESULTS

Lower glucose infusion rate was significantly associated with lower levels of HDL cholesterol in youths with Type 1 diabetes and with higher levels of triglycerides and higher triglyceride/HDL ratio in both youths and adults. The magnitude of the associations between glucose infusion rate and lipid levels translate into interquartile differences of 0.098 mmol/l for HDL cholesterol, 0.17 mmol/l for triglycerides and 1.06 for triglycerides/HDL in the adolescents and 0.20 mmol/l for triglycerides and 1.01 for triglycerides/HDL in the adults. The associations were attenuated and no longer statistically significant by adjustment for adiposity among adults, while adjustment for HbA(1c) had a small effect in youths and adults.

CONCLUSIONS

Lower insulin sensitivity is associated with a more atherogenic lipid profile in both youths and adults with Type 1 diabetes.

Association of exposure to diabetes in utero with adiposity and fat distribution in a multiethnic population of youth: the Exploring Perinatal Outcomes among Children (EPOCH) Study

AIMS/HYPOTHESIS

To evaluate whether exposure to maternal gestational diabetes (GDM) is associated with adiposity and fat distribution in a multiethnic population of children.

METHODS

Retrospective cohort study of 82 children exposed to maternal GDM and 379 unexposed youths 6-13 years of age with measured BMI, waist circumference, skinfold thickness, and visceral and subcutaneous abdominal fat.

RESULTS

Exposure to maternal GDM was associated with higher BMI (p = 0.02), larger waist circumference (p = 0.004), more subcutaneous abdominal fat (p = 0.01) and increased subscapular to triceps skinfold thickness ratio (p = 0.01) in models adjusted for age, sex, race/ethnicity and Tanner stage. Adjustment for socioeconomic factors, birthweight and gestational age, maternal smoking during pregnancy and current diet and physical activity did not influence associations; however, adjustment for maternal pre-pregnancy BMI attenuated all associations.

CONCLUSIONS/INTERPRETATION

Exposure to maternal GDM is associated with increased overall and abdominal adiposity, and a more central fat distribution pattern in 6- to 13-year-old youths from a multi-ethnic population, providing further support for the fetal overnutrition hypothesis.

Development, validation and use of an insulin sensitivity score in youths with diabetes: the SEARCH for Diabetes in Youth study

AIMS/HYPOTHESIS

The ability to measure insulin sensitivity across the phenotypic spectrum of diabetes may contribute to a more accurate characterisation of diabetes type. Our goal was to develop and validate an insulin sensitivity (IS) score using the euglycaemic-hyperinsulinaemic clamp in a subset (n = 85) of 12- to 19-year-old youths with diabetes participating in the SEARCH study in Colorado, USA.

METHODS

Youths with a diagnosis of type 1 (n = 60) or type 2 diabetes (n = 25) underwent a 3 h clamp to measure glucose disposal rate (GDR, mg kg⁻¹ min⁻¹). Demographic (age, sex, race), clinical (BMI, waist, Tanner stage) and metabolic characteristics (HbA₁(c), lipids, blood pressure, urine albumin:creatinine) were used to estimate log(e)IS score via stepwise linear regression on a model-development set (n = 53). Estimated IS score was evaluated for reproducibility on two validation sets: youths with diabetes (n = 33) and healthy control youths (n = 22).

RESULTS

The best model included waist, triacylglycerol (TG) and HbA₁(c) levels (R² = 0.74). Diabetes type did not enter the model and there were no significant interactions between diabetes type and other predictors. Estimated IS score correlated well (r = 0.65, p < 0.0001; r = 0.62, p = 0.002) with GDR on the two validation sets. Based on this analysis, we propose the following formula to estimate insulin sensitivity in youths with diabetes: [Formula: see text].

CONCLUSIONS/INTERPRETATION

Insulin sensitivity can be estimated in adolescents with diabetes using routinely collected measures. This score can be applied to epidemiological studies of youths with diabetes to characterise relationships between dimensions of diabetes type.

Association of glycaemia with lipids in adults with type 1 diabetes: modification by dyslipidaemia medication

AIMS/HYPOTHESIS

Hyperglycaemia and dyslipidaemia are common metabolic abnormalities in adults with type 1 diabetes and both increase cardiovascular disease (CVD) risk. The hypothesis of this study was that change in HbA(1c) over 6 years would be associated with change in fasting lipids in adults with type 1 diabetes.

METHODS

The Coronary Artery Calcification in Type 1 Diabetes (CACTI) study examined 652 patients with type 1 diabetes (54% female); 559 and 543 had follow-up visits at 3 and 6 years. Baseline age (mean ± SD) was 37 ± 9 years, diabetes duration 23 ± 9 years, and HbA(1c) 8.0 ± 1.3%. Use of dyslipidaemia medication was 17%, 32%, and 46% at the three visits. Separate longitudinal mixed models were fitted to examine the relationship between change in HbA(1c) and change in fasting total cholesterol (TC), HDL-cholesterol (HDL-c), LDL-cholesterol (LDL-c), log triacylglycerols (TG), and non-HDL-cholesterol (non-HDL-c). Because of an interaction between dyslipidaemia medication use and association of HbA(1c) with lipids, results were stratified by dyslipidaemia medication use.

RESULTS

Among patients not using dyslipidaemia medication, a higher HbA(1c) was associated with significantly worse levels of the lipids TC, LDL-c, TG and non-HDL-c (per 1% change in HbA1c, TC 0.101 mmol/l, 95% CI 0.050, 0.152; LDL-c 0.103 mmol/l, 95% CI 0.058, 0.148; TG 0.052 mmol/l, 95% CI 0.024, 0.081; and non-HDL-c 0.129 mmol/l, 95% CI 0.078, 0.180) but not HDL-c (-0.20 mmol/l, 95% CI -0.047, 0.007). The associations between HbA(1c) and any lipid outcome among those on dyslipidaemia medication were in the same direction, but attenuated compared with persons not on medication.

CONCLUSIONS/INTERPRETATION

Change in HbA(1c) is significantly associated with change in fasting lipids, but dyslipidaemia medications may be required to optimise lipid and cardiovascular health.

Association of a common G6PC2 variant with fasting plasma glucose levels in non-diabetic individuals

BACKGROUND/AIMS

Fasting plasma glucose (FPG) levels correlate with cardiovascular disease and mortality in both diabetic and non-diabetic subjects. G6PC2 encodes a pancreatic islet-specific glucose-6-phosphatase-related protein and G6pc2-null mice were reported to exhibit decreased blood glucose levels. Two recent genome-wide association studies have implicated a role for G6PC2 in regulation of FPGlevels in the general European population and reported the strongest association with the rs560887 SNP. The purpose of this study was to replicate this association in our independent epidemiological samples.

METHODS

DNA samples from non-Hispanic white Americans (NHWs; n = 623), Hispanic Americans (n = 410) and black Africans (n = 787) were genotyped for rs560887 using TaqMan allelic discrimination.

RESULTS

While no minor allele A of rs560887 was observed among blacks, its frequency was 33% in NHWs and 17.5% in Hispanics. The rs560887 minor allele was associated with reduced FPG levels in non-diabetic NHWs (p = 0.002 under an additive model). A similar trend of association was observed in non-diabetic Hispanics (p = 0.076 under a dominant model), which was more pronounced in normoglycemic subjects (p = 0.036).

CONCLUSIONS

Our results independently confirm the robust association of G6PC2/rs560887 with FPG levels in non-diabetic NHWs. The observed evidence for association in Hispanics warrants further studies in larger samples.

Childhood growth and age at diagnosis with Type 1 diabetes in Colorado young people

OBJECTIVE

Studies have suggested that the age at diagnosis of Type 1 diabetes (T1D) is decreasing over time. The overload hypothesis postulates that risk factors, such as accelerated growth, may be responsible for this decrease. We assessed changes in age, body mass index (BMI), weight and height at diagnosis with T1D in non-Hispanic white (NHW) and Hispanic (HISP) young people from Colorado, using data from the IDDM Registry and SEARCH Study.

METHODS

In three time periods, 656 (1978-1983), 562 (1984-1988) and 712 (2002-2004) young people aged 2-17 years were newly diagnosed with T1D. Age, weight, height and presence of diabetic ketoacidosis (DKA) at diagnosis with T1D were obtained from medical records. Trends over the three time periods were assessed with regression analyses.

RESULTS

Age at diagnosis decreased by 9.6 months over time (P = 0.0002). Mean BMI standard deviation score (SDS), weight SDS and height SDS increased over time (P < 0.0001), while prevalence of DKA decreased (P < 0.0001). Increasing height over time accounted for 15% (P = 0.04) of the decreasing age at diagnosis with T1D.

CONCLUSIONS

Our study provides evidence that increased linear growth, but not increased BMI or weight over time, may account, at least in part, for the younger age at diagnosis of T1D in Colorado children. This finding supports the hypothesis that increasing environmental pressure resulting from changes in potentially preventable risk factors may accelerate the onset of T1D in children.

Determinants of adiponectin levels in young people with Type 1 diabetes

AIMS

To determine whether adiponectin levels are higher in youth with Type 1 diabetes than in non-diabetic controls, and explore potential determinants for this difference.

METHODS

Data are from the SEARCH for Diabetes in Youth Case-Control Study. A total of 440 youth with Type 1 diabetes and 191 non-diabetic healthy controls age 10-22 years of non-Hispanic White (NHW), African-American (AA) and Hispanic (H) origin were included in this analysis. Mean adiponectin levels were compared between persons with diabetes and controls within each racial/ethnic group, sequentially adjusting for the following variables: demographic (age, sex, Tanner stage), kidney function (albumin: creatinin ratio: ACR), obesity (body mass index: BMI; waist circumference), behavioral (percent calories from fat, physical activity), and glucose control (hemoglobin A1c: HbA(1c)).

RESULTS

Mean adiponectin levels, adjusted for age, sex and Tanner stage, were higher in persons with Type 1 diabetes than in control subjects, among NHW (17.6 vs 13.0 microg/ml, P < 0.001) and H (17.2 vs 13.0, P = 0.01), and slightly higher but not significantly so among AA (14.5 vs 12.6, P = 0.1). The differences persisted after additionally adjusting for differences in ACR, BMI and waist circumference. We found a positive relationship between adiponectin and HbA(1c) in youth with Type 1 diabetes, even after adjustment for age, sex and race/ethnicity.

CONCLUSIONS

Adiponectin is higher in an ethnically diverse group of youth with Type 1 diabetes than in control subjects. The relationship between glycemic control and adiponectin in Type 1 diabetes requires further exploration.

The SPINK1 N34S mutation is not associated with Type 2 diabetes mellitus in a population of the USA

AIMS

Mutations in the serine protease inhibitor (SPINK1) gene have been associated with all forms of chronic pancreatitis. Recently, an association of SPINK1 mutations with early-onset Type 2 diabetes mellitus has been reported in patients from Bangladesh. Therefore, we determined the frequency of SPINK1 N34S mutations in patients with Type 2 diabetes mellitus from the USA.

METHODS

The study population of Hispanic and non-Hispanic white people consisted of 387 patients with Type 2 diabetes and familial clustering of the disease, 232 family members without diabetes, 259 patients with Type 2 diabetes without a family history, and 302 ethnically matched healthy controls as part of the San Luis Valley Diabetes Study. We performed linkage- and association-analysis in 82 multiplex families with Type 2 diabetes mellitus.

RESULTS

No significant linkage or allele sharing was detected between Type 2 diabetes mellitus and the SPINK1 locus. The frequency of the N34S mutation was determined by fluorescence polarization and was similar between patients (n = 14/387 patients with familial clustering; n = 2/259 patients without family history) and controls (n = 5/232 family members without diabetes; n = 10/302 individuals). Variables such as ethnicity, age of diabetes onset and percentage of individuals with impaired glucose tolerance did not differ significantly between carriers and homozygous normal individuals.

CONCLUSION

The SPINK1 N34S mutation appears not to predispose Hispanic or non-Hispanic white people from the USA to the development of Type 2 diabetes mellitus.

Abdominal obesity predicts declining insulin sensitivity in non-obese normoglycaemics: the Insulin Resistance Atherosclerosis Study (IRAS)

AIM

Cross-sectional studies have demonstrated a relationship between obesity and insulin sensitivity (S(I)); however, there is a lack of evidence from longitudinal studies.

METHODS

The Insulin Resistance Atherosclerosis Study (IRAS) estimated S(I) (x10(-4)/min.microU/ml) directly using a frequently sampled intravenous glucose tolerance test with minimal model analysis in 504 normoglycaemic subjects. Partial correlation coefficients (r) were calculated to compare the relationship of change in S(I) from baseline to 5 years later (DeltaS(I)) with baseline waist circumference (waist) as a measure of abdominal obesity and body mass index (BMI) as a measure of overall obesity. Mean DeltaS(I) was -1.06 (SD = 1.85).

RESULTS

Higher baseline waist (r = -0.16; p = 0.0005), but not BMI (r = -0.005; p = 0.91), was associated with (-) DeltaS(I) in models including sex, ethnicity, clinical centre and baseline S(I), BMI, waist, age and physical activity. The waist-DeltaS(I) relationship differed across the levels of baseline BMI, being significant only in normal weight (r = -0.21) and overweight subjects (r = -0.16), but not in obese subjects. DeltaS(I) was correlated with a 5-year change in either obesity measure (Deltawaist: r = -0.22 and DeltaBMI: r = -0.20; p = 0.0001).

CONCLUSIONS

Among non-diabetics, waist circumference was a strong predictor of declining S(I) among lean subjects, a modest predictor among overweight subjects, but was not predictive among obese individuals. Waist circumference should be considered, in addition to BMI, when identifying individuals at high risk of diabetes or the insulin resistance syndrome.

Admixture in the Hispanics of the San Luis Valley, Colorado, and its implications for complex trait gene mapping

Hispanic populations are a valuable resource that can and should facilitate the identification of complex trait genes by means of admixture mapping (AM). In this paper we focus on a particular Hispanic population living in the San Luis Valley (SLV) in Southern Colorado. We used a set of 22 Ancestry Informative Markers (AIMs) to describe the admixture process and dynamics in this population. AIMs are defined as genetic markers that exhibit allele frequency differences between parental populations >or=30%, and are more informative for studying admixed populations than random markers. The ancestral proportions of the SLV Hispanic population are estimated as 62.7 +/- 2.1% European, 34.1 +/- 1.9% Native American and 3.2 +/- 1.5% West African. We also estimated the ancestral proportions of individuals using these AIMs. Population structure was demonstrated by the excess association of unlinked markers, the correlation between estimates of admixture based on unlinked marker sets, and by a highly significant correlation between individual Native American ancestry and skin pigmentation (R2= 0.082, p < 0.001). We discuss the implications of these findings in disease gene mapping efforts.

Cladistic analysis of human apolipoprotein a4 polymorphisms in relation to quantitative plasma lipid risk factors of coronary heart disease

Genetic variation in several genes involved in lipid metabolism is known to affect population variation in quantitative lipid risk factor profiles for coronary heart disease (CHD). The apolipoprotein A-IV gene (APOA4) is one such candidate gene. We genotyped five polymorphisms in the APOA4 gene (codon 127, codon 130, codon347, codon 360 and 3' VNTR) and investigated their impact on plasma lipid trait levels in three populations comprising 604 U.S. non-Hispanic Whites (NHWs), 408 U.S. Hispanics and 708 Nigerian Blacks. Cladistic analysis was carried out to identify 5-site haplotypes that were associated with significant phenotypic differences in each population. The distribution of APOA4 genotypes was significantly different between ethnic groups. The Africans were monomorphic for two of the five sites (codons 130 and 360), but possess a unique 12 bp insertion that was not observed in NHWs and Hispanics. Due to linkage disequilibrium between the sites, only 6 haplotypes were observed in NHWs and Hispanics, and 4 in Africans. Several gender-and ethnic-specific associations between genotypes and plasma lipid traits were observed when single sites were used. Several haplotypes were identified by cladistic analysis that may carry functional mutations that affect plasma lipid trait levels.

Low serum and red blood cell folate are moderately, but nonsignificantly associated with increased risk of invasive cervical cancer in U.S. women

Previous observational epidemiologic studies of folate and cervical cancer, as well as folate supplementation trials for cervical dysplasia, have produced mixed results. We examined the relationship between serum and RBC folate and incident invasive cervical cancer in a large, multicenter, community-based case-control study. Detailed in-person interviews were conducted, and blood was drawn at least 6 mo after completion of cancer treatment from 51% of cases and 68% of controls who were interviewed. Blood folate was measured with both microbiologic and radiobinding assays. Included in the final analyses were 183 cases and 540 controls. Logistic regression was used to control for all accepted risk factors, including age, sexual behavior, smoking, oral contraceptive use, Papanicolaou smear history and human papillomavirus (HPV)-16 serology. For all four folate measures, the geometric mean in cases was lower than in controls (e.g., 11.6 vs. 13.0 nmol/L, P < 0.01 for the serum radiobinding assay). Folate measures using microbiologic and radiobinding assays were correlated (serum: r = 0.90; RBC: r = 0.77). For serum folate, multivariate-adjusted odds ratios (OR) in the lowest vs. highest quartile were 1.3 [95% confidence interval (CI) = 0.8--2.9] and 1.6 (0.9--2.9), using the microbiologic and radiobinding assays, respectively. For RBC folate, comparable OR were 1.2 (0.6--2.2) and 1.5 (0.8--2.7). Similar risks were obtained when restricting analyses to subjects with a history of HPV infection. Thus, low serum and RBC folate were each moderately, but nonsignificantly, associated with increased invasive cervical cancer risk. These findings support a role for one-carbon metabolism in the etiology of cervical cancer.

A case-control study of physical activity and non-insulin dependent diabetes mellitus (NIDDM). the San Luis Valley Diabetes Study

PURPOSE

The purpose of this study was to examine the association between physical activity and non-insulin dependent diabetes mellitus (NIDDM).

METHODS

We conducted a population-based case-control study in Hispanic and non-Hispanic white men and women, ages 20-74. A total of 167 cases with NIDDM and 1100 controls with normal glucose tolerance were included. All subjects completed an oral glucose tolerance test.

RESULTS

Persons with recently diagnosed NIDDM reported significantly lower levels of physical activity than control subjects. For total metabolic units, the odds ratio for subjects in the highest tertile compared to those in the lowest tertile was 0.60 (95% confidence interval (CI) = 0.37-0.98) after adjusting for age, sex, ethnicity, and family history of diabetes. The adjusted odds ratio for persons reporting high levels of vigorous activity (at least three times per week for 20 minutes) was also less than 1, but was not statistically significant (odds ratio (OR) = 0.73, 95% CI = 0.47-1.14). Similar adjusted odds ratios were observed for high versus low levels of self-assessed work activity (OR = 0.50, 95% CI = 0.34-0.74) and leisure time physical activity (OR = 0.62, 95% CI = 0.44-0.90). Further adjustments for body mass index attenuated the strength of the association between physical activity and NIDDM. This is consistent with the hypothesis that obesity is one consequence of physical inactivity that puts individuals at increased risk for NIDDM. The association of physical activity and NIDDM was stronger in Hispanic than in non-Hispanic white subjects, although this difference was not statistically significant.

CONCLUSIONS

High levels of physical activity are associated with lower odds of NIDDM and this relationship may be stronger in Hispanic subjects.

Elevated serum homocysteine levels and increased risk of invasive cervical cancer in US women

OBJECTIVES

To explore the relationship between serum homocysteine, a sensitive biomarker for folate inadequacy and problems in one-carbon metabolism, and invasive cervical cancer.

METHODS

A large case-control study was conducted in five US areas with up to two community controls, obtained by random-digit dialing, individually matched to each case. Cervical cancer risk factors were assessed through at-home interview. Blood was drawn at least 6 months after completion of cancer treatment from 51% and 68% of interviewed cases and controls. Serum homocysteine was measured by high-performance liquid chromatography, and exposure to human papillomavirus (HPV) type 16, the most prevalent oncogenic type, was assessed using an enzyme-linked immunosorbent assay. Cases with advanced cancer and/or receiving chemotherapy were excluded, leaving 183 cases and 540 controls.

RESULTS

Invasive cervical cancer risk was substantially elevated for women in the upper three homocysteine quartiles (> 6.31 micromol/L); multivariate-adjusted odds ratios ranged from 2.4 to 3.2 (all 95% CIs excluded 1.0). A trend was apparent and significant (p = 0.01). When cases were compared with HPV-16 seropositive controls only, odds ratios were comparable.

CONCLUSIONS

Serum homocysteine was strongly and significantly predictive of invasive cervical cancer risk. This association could reflect folate, B12 and/or B6 inadequacy, or genetic polymorphisms affecting one-carbon metabolism.

Individual and community risks of measles and pertussis associated with personal exemptions to immunization

CONTEXT

The risk of vaccine-preventable diseases among children who have philosophical and religious exemptions from immunization has been understudied.

OBJECTIVES

To evaluate whether personal exemption from immunization is associated with risk of measles and pertussis at individual and community levels.

DESIGN, SETTING, AND PARTICIPANTS

Population-based, retrospective cohort study using data collected on standardized forms regarding all reported measles and pertussis cases among children aged 3 to 18 years in Colorado during 1987-1998.

MAIN OUTCOME MEASURES

Relative risk of measles and pertussis among exemptors and vaccinated children; association between incidence rates among vaccinated children and frequency of exemptors in Colorado counties; association between school outbreaks and frequency of exemptors in schools; and risk associated with exposure to an exemptor in measles outbreaks.

RESULTS

Exemptors were 22.2 times (95% confidence interval [CI], 15.9-31.1) more likely to acquire measles and 5.9 times (95% CI, 4.2-8.2) more likely to acquire pertussis than vaccinated children. After adjusting for confounders, the frequency of exemptors in a county was associated with the incidence rate of measles (relative risk [RR], 1.6; 95% CI, 1.0-2.4) and pertussis (RR, 1.9; 95% CI, 1.7-2.1) in vaccinated children. Schools with pertussis outbreaks had more exemptors (mean, 4.3% of students) than schools without outbreaks (1. 5% of students; P =.001). At least 11% of vaccinated children in measles outbreaks acquired infection through contact with an exemptor.

CONCLUSIONS

The risk of measles and pertussis is elevated in personal exemptors. Public health personnel should recognize the potential effect of exemptors in outbreaks in their communities, and parents should be made aware of the risks involved in not vaccinating their children.

Depressive symptoms in Hispanic and non-Hispanic White rural elderly: the San Luis Valley Health and Aging Study

Literature on depression in rural and Hispanic elderly adults is sparse. This report describes the prevalence of depressive symptoms in 1,151 community-dwelling, Hispanic and non-Hispanic White participants in the San Luis Valley Health and Aging Study, conducted in rural Colorado during 1993-1995. The prevalence and odds ratios of high depressive symptoms, defined as a Center for Epidemiologic Studies Depression Scale score of > or = 16, were calculated. The crude prevalence of high depressive symptoms was 11.4% (95% confidence interval: 9.6, 13.6). Female gender, chronic diseases, dissatisfaction with social support, living alone, and lower income and education were associated with depressive symptoms. There were no ethnic differences in the men. The age-adjusted odds ratio of depressive symptoms in Hispanic women compared with that of non-Hispanic White women was 2.11 (95% confidence interval: 1.32, 3.38). After adjustment for multiple sociodemographic and health risk factors, the odds ratio in Hispanic women was 2.12 (95% confidence interval: 1.19, 3.80). Higher depressive symptoms in Hispanic women varied by acculturation level. The odds ratio in the high acculturation stratum was 1.56 (95% confidence interval: 0.75, 3.27) and in the low acculturation stratum was 2.51 (95% confidence interval: 1.11, 5.70). A lower acculturation level may increase the risk for depression in older Hispanic women.

Apolipoprotein A polymorphisms and plasma lipoprotein(a) concentrations in non-Hispanic Whites and Hispanics

Elevated levels of plasma lipoprotein(a) [Lp(a)] are thought to be a risk factor for atherosclerosis and coronary heart disease. Plasma levels of Lp(a) are highly variable between individuals, ranging from 0.1 mg/dL to > 100 mg/dL These levels are under strict genetic control, and genetic variation in the apolipoprotein A (APOA) gene accounts for almost all variation in Lp(a) levels. In this study, we investigated the relationship between two APOA polymorphisms (kringle 4 and 5' pentanucleotide repeat) and plasma Lp(a) levels in normoglycemic non-Hispanic Whites (NHWs) (n = 390) and Hispanics (n = 214) from the San Luis Valley, Colorado. Mean (+/- SD) and median Lp(a) levels were 9.6 +/- 12.5 mg/dL and 3.8 mg/dL, respectively, in NHWs and 12.1 +/- 15.6 mg/dL and 4.9 mg/dL, respectively, in Hispanics. The number of observed kringle 4 repeats ranged from 11 to 38 in NHWs and from 10 to 41 in Hispanics. Spearman rank correlation revealed an inverse relationship between the size of the kringle 4 repeat and plasma Lp(a) levels in both populations (r = -0.38; p < 0.0001 in NHWs and r = -0.64; p < 0.0001 in Hispanics). About 30% and 48% of the variation in plasma Lp(a) was explained by this polymorphism in NHWs and Hispanics, respectively. This study confirms that the kringle 4 polymorphism in the APOA gene is a significant determinant of Lp(a) levels in both study groups. A pentanucleotide repeat polymorphism in the 5' promoter region of the APOA gene did not show significant impact on plasma Lp(a) levels in either NHWs or Hispanics.

DNA sequence variation in human apolipoprotein C4 gene and its effect on plasma lipid profile

Human apolipoprotein C-IV (apoC-IV, protein; APOC4, gene) is a new member of the APO E/C1/C2 gene cluster. In transgenic mice, human apoC-IV is predominantly associated with very low-density lipoprotein (VLDL) and thus may play an important role in lipid metabolism. To our knowledge, the extent and nature of APOC4 genetic variation and its role in lipid metabolism are unknown. In this study we have assessed the presence of genetic variation in all three exons of APOC4 and their flanking intronic sequence by SSCP and DNA sequencing. A total of five point mutations were observed, including two in the non-coding part of exon 1 (A609G and G620A), two in exon 2 (codons 36 and 52) and one in exon 3 (codon 96). The three mutations in exons 2 and 3 predict amino acid substitutions, Leu36Pro, Gly52Asp, and Leu96Arg. The frequencies of the variant alleles were: 0.010 for 609G, 0.039 for 620A, 0.502 for Pro36, 0.003 for Asp52 and 0.357 for Arg96. Significant pairwise linkage disequilibrium was observed between five of the ten APOC4 pairs, including nt. 620/codon 36, nt. 620/codon 96, codon 36/codon 52, codon 36/codon 96 and codon 52/codon 96. A general linear model analysis reveled a significant association of the Leu36Pro and the Leu96Arg polymorphisms with triglyceride levels in women. This is consistent with the proposed role of apoC-IV in triglyceride metabolism. The characterization of APOC4 genetic variation may lead to the identification of a specific role of apoC-IV in lipid metabolism or in other physiologic pathways.

Genetic screening of the lipoprotein lipase gene for mutations associated with high triglyceride/low HDL-cholesterol levels

The lipoprotein lipase (LPL) enzyme plays a major role in lipid metabolism, primarily by regulating the catabolism of triglyceride (TG)-rich lipoprotein particles. The gene for LPL is an important candidate for affecting the risk of atherlosclerosis in the general population. Previously, we have shown that the HindIII polymorphism in intron 8 of the LPL gene is associated with plasma TG and HDL-cholesterol variation in Hispanics and non-Hispanic whites (NHWs). However, this polymorphism is located in an intron and hence may be in linkage disequilibrium with a functional mutation in the coding region or intron-exon junctions of the LPL gene. The aim of this study was to initially screen the LPL coding region and the intron-exon junctions by single-strand conformation polymorphism (SSCP) analysis for mutation detection in a group of 86 individuals expressing the phenotype of high TG/low HDL, followed by association studies in a population-based sample of 1,014 Hispanics and NHWs. Four sequence variations were identified by SSCP and DNA sequencing in the coding region of the gene, including two missense mutations (D9N in exon 2 and N291S in exon 6), one samesense mutation (V108V in exon 3), and one nonsense mutation (S447X in exon 9). Multiple regression analyses, including these four mutations and the HindIII polymorphic site, indicate that the association of the HindIII site with plasma TG (P=0.001 in NHWs and P=0.002 in Hispanics) and HDL-cholesterol (P=0.007 in NHWs and P=0.127 in Hispanics) is independent of all other LPL variable sites examined. These observations reinforce the concept that the intronic 8 HindIII site is functional by itself and provide a strong rationale for future comprehensive functional studies to delineate its biological significance.

Gender-specific nonrandom association between the alpha 1-antichymotrypsin and apolipoprotein E polymorphisms in the general population and its implication for the risk of Alzheimer's disease

A common polymorphism in the alpha 1-antichymotrypsin (ACT) gene has been found co modify the APOE*4-associated risk of Alzheimer's disease due to an apparent interaction between the two loci. This study was undertaken to determine the gender- and age-related distributions of these two polymorphisms in two large population-based samples of Caucasians (n = 803) and Nigerian Blacks (n = 730). Significantly higher frequencies of the ACT*A (78.6% vs. 48.4%; P < 0.001) and APOE*4 (25.6% vs. 15.6%; P < 0.001) alleles were observed in Nigerian Blacks than in Caucasians. In Caucasian women but not in men, the frequency of the APOE*4 allele was significantly lower in the ACT/AA genotype as compared to the ACT/AT and ACT/TT genotypes, while a reverse trend was seen for the APOE*3 allele frequency among the ACT genotypes. The distribution of the ACT*A allele between the APOE*4 carriers and non-APOE*4 carriers was also different in Caucasian women but not in men. A similar gender-specific nonrandom association between the two polymorphisms was observed in Black women but this was not as strong as observed in Caucasian women. When the two samples were stratified by age group, an association or trend of association was observed in all age groups in women only. These data indicate the existence of a nonrandom association between the APOE and ACT loci in women which may have an important implication for the higher prevalence of Alzheimer's disease in women.

Cognitive functioning and impairment among rural elderly Hispanics and non-Hispanic whites as assessed by the Mini-Mental State Examination

We conducted a cross-sectional study to determine the distribution of cognitive functioning as measured by the Mini-Mental State Examination (MMSE) among a sample of Hispanic and non-Hispanic White (NHW) residents from two counties in rural, southern Colorado. Residents aged 60 years and older (N = 1,360) were administered the full MMSE, a sociodemographic and medical interview. Protocols were developed to administer the MMSE equitably in both ethnic groups. Younger Hispanics tended to be categorized as severely impaired more than similarly aged NHWs (OR at age 70 = 4.14), however, older Hispanics and NHWs performed similarly after adjusting for education and gender (OR at age 90 = 1.00). The use of a modified MMSE scale that removed the ethnic bias demonstrated that NHWs and Hispanics had similar levels of severe impairment after full adjustment (OR = 0.93). Given the widespread use of the MMSE, these findings indicate the need for further validation of this instrument.

Genetic variation in the apolipoprotein H (beta2-glycoprotein I) gene affects plasma apolipoprotein H concentrations

Apolipoprotein H (apoH, protein; APOH, gene) is a single chain glycoprotein that exists in plasma both in a free form and in combination with lipoprotein particles. ApoH has been implicated in several physiologic pathways, including lipid metabolism, coagulation, and the production of antiphospholipid antibodies. The wide range of interindividual variation in plasma apoH levels is thought to be under genetic control, but its molecular basis is unknown. APOH displays a common structural polymorphism with the occurrence of three common alleles (APOH*1, APOH*2, and APOH*3), the APOH*2 allele being the most frequent in all populations. The relationship between the APOH polymorphism and plasma apoH levels is unknown. In this study, we have determined the impact of this APOH polymorphism on apoH levels in 455 normoglycemic non-Hispanic Whites (220 men and 235 women) from the San Luis Valley, Colorado. Mean plasma apoH levels, determined by capture enzyme-linked immunosorbent assay, were 20.0 +/- 0.2 mg/dl (range: 3.4-31.2 mg/dl) with no significant difference between men and women. In women, but not in men, age had a significant effect on plasma apoH levels explaining 3.4% of its phenotypic variance. ApoH levels also correlated positively with cholesterol (P = 0.015), HDL-cholesterol (P = 0.044), and triglyceride (P = 0.037) in women, but not in men. An analysis of variance (ANOVA) of adjusted plasma apoH levels showed significant association with the APOH polymorphism in both men and women (P < 0.0001), and the APOH polymorphism accounted for 11.4% and 13.6% of the variation in apoH levels in men and women, respectively. Compared with the APOH*1 and APOH*2 alleles, the APOH*3 allele was associated with significantly lower plasma apoH levels. At the molecular level, APOH*3 can be further subdivided into two distinct forms, called APOH*3W and APOH*3B. The APOH*3W form is more common in US Whites and is the result of a missense mutation at codon 316. An ANOVA for the codon 316 polymorphism revealed that this polymorphism is a major determinant of plasma apoH variation (P < 0.0001). This study indicates that common genetic variation in the APOH gene is a significant determinant of plasma apoH levels in non-Hispanics Whites and should be useful in evaluating the role of the APOH genetic variation in various metabolic pathways in which apoH has been implicated.

Methods and prevalence of ADL limitations in Hispanic and non-Hispanic white subjects in rural Colorado: the San Luis Valley Health and Aging Study

PURPOSE

The Hispanic population in the United States is the fastest growing minority group, yet there is little understanding of the disability patterns that occur as this population ages. We conducted a cross-sectional study to define the prevalence of limitations of activities of daily living (ADL) and measures of observed function.

METHODS

We censussed two rural counties in southern Colorado and selected a stratified sample of both Hispanic and non-Hispanic white (NHW) residents; 81.6% completed the protocol.

RESULTS

Among the 1250 subjects aged 65 years and older, Hispanic elderly living in the community had greater ADL disability than NHW subjects, both for any difficulty (p = 0.006), and for needing assistance (p = 0.002). Hispanic persons were less likely to reside in nursing homes (3.4%) compared with NHW persons (9.3%). Hispanic elderly had excess prevalence of dependent ADL tasks (needs assistance or unable to do), (age, gender-adjusted odds ratio = 1.39, 95% CI = 1.01-1.92) in community dwelling and nursing home residents combined. There was no Hispanic excess of less severe difficulty compared with NHW persons, and there was a similar prevalence of limitation on observed functional tasks (timed walk, stooping, rising from a chair) in both groups.

CONCLUSIONS

There was a modest Hispanic excess of reported dependent ADL limitation, and no excess of observed functional difficulties. Hispanics enter older age with much less income and education, yet they do not have a marked excess prevalence of limitations in activities of daily living when compared with NHW persons living in the same area.

Indicators of nutritional risk in a rural elderly Hispanic and non-Hispanic white population: San Luis Valley Health and Aging Study

OBJECTIVE

To describe the prevalence of nutritional risk factors among elderly residents in a rural Hispanic and non-Hispanic white population.

DESIGN

A geographically based survey of community-dwelling elderly adults.

SUBJECTS/SETTING

From July 1993 to July 1995, all Hispanic persons older than 65 years and an age-stratified, random sample of 69% of non-Hispanic white persons, from 2 Colorado counties, were invited to participate in a study of functional impairment and disability (81% responded). After exclusion of 184 respondents who required a surrogate respondent and 8 with missing diet data, the study consisted of 1,006 subjects. Interviews included questions similar to the Nutrition screening Initiative checklist, a 21-item food frequency questionnaire, and anthropometric measures.

STATISTICAL ANALYSES PERFORMED

Gender- and ethnicity-specific, age-adjusted prevalence for each risk factor was estimated by use of logistic regression.

RESULTS

Hispanic participants were more likely than non-Hispanic whites to report inadequate intake of vegetables, problems with teeth or dentures that limited the kinds and amounts of food eaten, difficulty preparing meals, and lack of money needed to buy food. Hispanic women reported nutritional risk factors more often than Hispanic men, although anthropometric markers indicated that Hispanic men may be at higher risk of nutritional deficiency.

APPLICATIONS/CONCLUSIONS

Hispanic men and women had a higher prevalence of nutritional risk factors than non-Hispanic whites. Intervention programs targeting rural, elderly Hispanics should aim to ensure that basic nutrition needs (access to food, help preparing meals, and adequate dental care) are being met. Community programs to increase activity levels and consumption of nutrient-dense foods are recommended.

Association of antibodies to beta2-glycoprotein 1 with pregnancy loss and pregnancy-induced hypertension: a prospective study in low-risk pregnancy

OBJECTIVE

To determine whether higher levels of anti-beta2-glycoprotein 1 before 25 weeks' gestation are independently associated with either pregnancy loss or pregnancy-induced hypertension.

METHODS

Serum samples for the immunoglobulin (Ig) G and IgM isotypes of anti-beta2-glycoprotein 1, anticardiolipin antibody, and antiphosphatidylserine were collected from 325 low-risk nulliparas who presented for prenatal care before 25 weeks' gestation. This cohort was followed prospectively for the development of pregnancy loss and pregnancy-induced hypertension.

RESULTS

The adjusted odds ratios (OR) and 95% confidence intervals (CI) of elevated antiphospholipid antibody levels for pregnancy loss were: IgG anti-beta2-glycoprotein 1, OR 1.2 (CI 0.5, 2.8); IgG anticardiolipin antibody, OR 8.4 (CI 2.3, 31); and IgG antiphosphatidylserine, OR 5.2 (CI 1.4, 18.7). The relative risks of pregnancy loss for all IgG antiphospholipid antibodies were higher among women who had blood collected after 10 weeks' gestation compared with those studied before 10 weeks' gestation. However, there were only marginal differences in the attributable risks, suggesting that the impact of elevated levels of antiphospholipid antibodies might be similar in early and later stages of pregnancy. None of the antiphospholipid antibodies was associated with pregnancy-induced hypertension.

CONCLUSION

In this study, elevated levels of IgG anticardiolipin and IgG antiphosphatidylserine antibodies were markers of pregnancy loss, but an elevated level of anti-beta2-glycoprotein was not a strong predictor of fetal loss.

Antioxidant nutrient intake and diabetic retinopathy: the San Luis Valley Diabetes Study

OBJECTIVE

Diabetic retinopathy (DR) is a major cause of visual impairment and blindness in adults. Antioxidant nutrients, such as vitamins C and E and beta-carotene, may be protective of some eye disorders, such as cataract and age-related macular degeneration, but a relationship between these nutrients and DR has yet to be defined. The purpose of this study was to examine the relation between dietary and supplement intakes of vitamins C, E, and beta-carotene and the risk of DR.

DESIGN

Both cross-sectional and longitudinal data were collected from participants in the San Luis Valley Diabetes Study, including non-Hispanic white and Hispanic adults in southern Colorado.

PARTICIPANTS

A total of 387 participants with type 2 diabetes completed at least 1 complete retinal examination and 24-hour dietary recall (including vitamin supplement use).

MAIN OUTCOME MEASURES

Type 2 diabetes was defined according to World Health Organization criteria. DR was assessed by retinal photographs, using the Airlie House criteria to classify DR as none, background, preproliferative, or proliferative. Data for both eyes, from up to three clinic visits per participant, were used for analysis. Ordinal logistic regression analysis was used, taking advantage of multiple clinic visits by individual participants and observations from both eyes, to assess the risk for increased DR severity over time as a function of changes in intake of vitamin C, vitamin E, and beta-carotene. Six categories of intake for each nutrient (first to fourth quintiles and ninth and tenth deciles) were considered to ascertain any potential threshold effect. Analyses accounted for age, duration of diabetes, insulin use, ethnicity, glycated hemoglobin, hypertension, gender, and caloric intake.

RESULTS

An increase over time in vitamin C intake from the first to ninth deciles was associated with a risk for increased severity of DR (odds ratio = 2.21, P = 0.01), although excess risk was not observed for the tenth decile or the second through fourth quintiles compared to the first quintile. Increased intake of vitamin E was associated with increased severity of DR among those not taking insulin (odds ratios = 2.69, 2.59, 3.33, 5.65, 3.79; P < 0.02, for an increase over time from the first to the second through fourth quintiles and ninth and tenth deciles, respectively). Among those taking insulin, increased intake of beta-carotene was associated with a risk for severity of DR (odds ratio = 3.31, P = 0.003, and 2.99, P = 0.002, respectively, for the ninth and tenth deciles compared to the first quintile).

CONCLUSIONS

No protective effect was observed between antioxidant nutrients and DR. Depending on insulin use, there appeared to be a potential for deleterious effects of nutrient antioxidants. Further research is needed to confirm associations of nutrient antioxidant intake and DR.

Relationships between insulin resistance and lipoproteins in nondiabetic African Americans, Hispanics, and non-Hispanic whites: the Insulin Resistance Atherosclerosis Study

The study purpose was to explore the association between dyslipidemia and insulin resistance in three ethnic groups. The Insulin Resistance Atherosclerosis Study (IRAS) is a multicenter epidemiologic study conducted at four clinical centers in California, Texas, and Colorado. The study population for this analysis consisted of 931 non-Hispanic white, African American, and Hispanic men and women (aged 45 to 64 years) without diabetes. The IRAS clinical examinations included lipoprotein measures, a 75-g glucose tolerance test, and the frequently sampled intravenous glucose tolerance (FSIGT) test. The results show a consistent relationship between insulin-mediated glucose disposal and dyslipidemia in African American, Hispanic, and non-Hispanic white men and women. Further, LDL size was inversely associated with insulin resistance in all three ethnic groups. These findings indicate that dyslipidemia is a fundamental part of the insulin resistance syndrome in all of the ethnic groups studied.

The association of non-insulin-dependent diabetes mellitus with perceived quality of life in a biethnic population: the San Luis Valley Diabetes Study

OBJECTIVES

This study evaluated the association between quality of life and non-insulin-dependent diabetes mellitus (NIDDM) status, and whether this association differs between Hispanics and non-Hispanic Whites.

METHODS

Between 1986 and 1989, cross-sectional data on perceived quality of life (PQOL) were collected from 223 persons with NIDDM and 753 non-diabetic subjects.

RESULTS

After adjustment, persons with NIDDM rated their PQOL significantly lower than did control subjects. The relationship of diabetes and PQOL did not differ by ethnicity. The number of complications of diabetes was not associated with lower PQOL scores.

CONCLUSIONS

Control and treatment strategies should reflect an understanding of the impact that diabetes has on social functioning, leisure activities, and physical and mental health.

Multiple organ failure can be predicted as early as 12 hours after injury

BACKGROUND

The failure of therapies aimed at modulating systemic inflammatory response syndrome and decreasing multiple organ failure (MOF) has been attributed in part to the inability to identify early the population at risk. Our objective, therefore, was to develop predictive models for MOF at admission and at 12, 24 and 48 hours after injury.

METHODS

Logistic regression models were derived in a data set with 411 adult trauma patients using indicators of tissue injury, shock, host factors, and the Acute Physiology Score-Acute Physiology and Chronic Health Evaluation III (APS-APACHE III).

RESULTS

MOF was diagnosed in 78 patients (19%). Injury Severity Score, platelet count, and age emerged as predictors in all models. Transfused blood, inotropes, and lactate were significant predictors at 12, 24, and 48 hours, but not at admission. The APS-APACHE III emerged only in the 0- to 48-hour model and offered minimal improvement in predictive power. Good predictive power was achieved at 12 hours after injury.

CONCLUSION

Postinjury MOF can be predicted as early as 12 hours after injury. The APS-APACHE III added little to the predictive power of tissue injury, shock and host factors.

Social network factors associated with perceived quality of life. The San Luis Valley Health and Aging Study

Demographic and social network factors associations with perceived quality of life (PQOL) were examined in a sample of rural Hispanic and non-Hispanic White (NHW) elderly. A 20-item PQOL scale measured participants' satisfaction with multiple facets of their lives. Age, gender, marital status, and living alone were not associated with this outcome. Hispanic persons with higher incomes had consistently higher ratings of quality of life compared to NHWs. More education was associated with a higher PQOL rating only among NHWs. More close friends and relatives, visiting in homes, and participation in outside activities were all independently related to PQOL. Interaction tests showed that the impact of social networks was stronger in NHWs. These findings suggest that network size and contact are important social factors that can improve quality of life for both ethnic groups. However, differences may need to be examined when judging the magnitude of these associations and when planning interventions.

Higher instrumental activities of daily living disability in Hispanics compared with non-Hispanic whites in rural Colorado. The San Luis Valley Health and Aging Study

This study examined Hispanic versus non-Hispanic white patterns of needing assistance with instrumental activities of daily living (IADL). The authors interviewed 798 Hispanic and 614 non-Hispanic white residents of rural Colorado, who were aged 60 years and older between 1993 and 1995. Seventy-five participants were nursing home residents at the time of the interview. Community-dwelling Hispanics were 1.6 times as likely as non-Hispanic whites to need assistance with at least one IADL task (95% confidence interval 1.25-2.13). A larger proportion of disabled non-Hispanic whites were in nursing homes but, after including nursing home residents, Hispanics remained significantly more likely to need assistance on at least one IADL task (odds ratio = 1.49, 95% confidence interval 1.16-1.93). Hispanics were also more likely to have difficulty on observed performance tasks. The Hispanic excess was not removed by adjusting for chronic disease, reported difficulty walking, or income. English language proficiency adjustment lowered the Hispanic excess, but adjusting for years of education or Mini-Mental State Examination scores more completely removed the ethnic differences. Higher education was protective for both Hispanic and non-Hispanic white elderly. Efforts to further investigate what facets or correlates of education are operating may offer useful insights into limiting IADL difficulties in future cohorts.

Identification and treatment of cystic fibrosis-related diabetes. A survey of current medical practice in the U.S

OBJECTIVE

To describe physicians' attitudes and practices in screening for and treating abnormalities in glucose homeostasis in cystic fibrosis (CF) patients and to test the hypotheses that guidelines for screening for CF-related diabetes (CFRD) are not followed at most centers and that screening and treatment vary by the care provider's background.

RESEARCH DESIGN AND METHODS

This cross-sectional survey included three groups of physicians: 1) 593 members of the Lawson Wilkins Pediatric Endocrine Society (LWPES), 2) 462 members of the pediatric assembly of the American Thoracic Society (ATS), and 3) 194 directors of cystic fibrosis centers (CFD). A mailed questionnaire was used for the survey.

RESULTS

The overall response rate was 67%. Of these, 224 LWPES, 143 ATS, and 135 CFD physicians reported actively seeing CF patients. About two-thirds of CF physicians (ATS and CFD) reported routine screening for impaired glucose tolerance (IGT) in asymptomatic CF patients; a random glucose is most often used (60%), followed by HbA1c (50%), urine glucose (44%), fasting glucose (21%), and oral glucose tolerance test (2%). Only 40% of LWPES physicians reported intervening for stress-induced hyperglycemia, but 61% reported use of insulin for persistent IGT. Management of CFRD was similar for all groups; most physicians used insulin (91%). LWPES recommended more intensive glucose testing and nutritional guidelines than did ATS/CFD (P < 0.0001). LWPES reported less concern about risks of diabetes complications (P < 0.0001) and the importance of minimizing burdensome interventions (P < 0.01). All groups considered weight management a top priority.

CONCLUSIONS

Screening for IGT is not routinely done in CF patients and screening tests vary. Greater agreement exists on methods of treating patients with persistent IGT or CFRD, although goals and aggressiveness of treatment vary with the provider's background. A consensus conference is recommended.

Prevalence of CD8+ T-cell expansions in relation to age in healthy individuals

Clonal CD8+ T-cell expansions have been identified in the peripheral blood of healthy adults and occasionally in children. These expansions are often large, yet their etiology is unknown. This study evaluated the relationship between age and the prevalence of these expansions in a healthy population (n = 147) aged 9 months to 85 years. Expansions were determined using immunofluorescence staining with monoclonal antibodies to different T-cell receptor (TCR)-variable regions. The overall prevalence was 13.6% and increased linearly with age as follows: 0% for 9-month-olds, 2.7% for 4- to 12-year-olds, 13.3% for 20- to 30-year-olds, 20.7% for 35- to 50-year-olds, and 33.4% for 65- to 85-year-olds. Multiple expansions were observed only in the oldest group. Certain TCR-variable regions appeared to be preferentially utilized by these expansions, which suggests a response to a particular antigenic stimulus. Childhood illness and vaccination histories did not provide insight into the etiology of these expansions. Age was the only measured factor that was associated with these expansions.

Executive cognitive abilities and functional status among community-dwelling older persons in the San Luis Valley Health and Aging Study

OBJECTIVES

The purpose of this study was to evaluate the contribution of the executive cognitive functions to self-reported and observed performance of activities of daily living and instrumental activities of daily living.

DESIGN

These data were collected as part of a cross-sectional survey of community-dwelling older persons, using statistical sampling, in a two-county area of southern Colorado.

SETTING

Participants were interviewed and administered measures of general cognition, depression, executive functioning, and performance of self-care and instrumental activities, either in their homes or at the study clinic.

PARTICIPANTS

A total of 1158 community-dwelling persons between the ages of 60 and 99 participated. Of these, 657 were female, 501 were male, 637 were Hispanic, and 521 were non-Hispanic whites.

MEASUREMENTS

Subjects were administered the Mini-Mental State Exam (MMSE), a measure of executive functioning (the Behavioral Dyscontrol Scale), the Center for Epidemiologic Studies Depression scale (CES-D), and the Structured Assessment of Independent Living Skills (SAILS, a measure of observed performance of daily tasks). They also were interviewed regarding their reported ADL and IADL status using measures from the Longitudinal Study on Aging.

RESULTS

Both general mental status and executive functioning demonstrated statistically significant univariate associations with all seven functional status measures (both self-report and observed performance). In a series of ordinary least squares regression models, executive functioning was a predictor for self-reported ADLs and observed performance of complex IADL tasks such as managing money and medications. Mental status did not predict self-reported functioning but was a predictor of observed performance. Depression was a significant variable for self-report measures but not for observed performance. Executive functioning and general mental status demonstrated some degree of independence from one another.

CONCLUSION

Executive functioning is an important determinant of functional status for both self-reported and observed ADLs and IADLs and should be assessed routinely when evaluating the mental status and functional abilities of older people. These results replicate and extend previous research on executive functioning among older persons by examining these factors in a large bi-ethnic community sample.

Racial differences in the distribution of a low density lipoprotein receptor-related protein (LRP) polymorphism and its association with serum lipoprotein, lipid and apolipoprotein levels

The low density lipoprotein (LDL) receptor-related protein (LRP) is a cell receptor that has close structural homology to the LDL and very low density lipoprotein receptors and thus is believed to play an important role in lipid metabolism. This study was carried out to evaluate the distribution of a known tetranucleotide repeat polymorphism in the LRP gene and its association with serum lipoprotein-lipid and apolipoprotein levels in four large samples comprising Hispanics (n=373) and non-Hispanic Whites (n=522) from the U.S. and Nigerian Blacks from Sokoto (n=390) and Benin (n=800). A total of four alleles, designated 83, 87, 91 and 95 bp, were observed. The 83 bp allele was observed at 0.4-1.1% in the two U.S. populations but was completely absent in African Blacks. Sokoto Blacks had significantly different frequencies of the 87 and 91 bp alleles compared to Hispanics (P=0.008) and non-Hispanic Whites (P=0.024). The frequency of the 91 bp allele was also significantly higher in Benin Blacks compared to Hispanics (P=0.026) and non-Hispanic Whites (P=0.054). The analysis of the relationship between the LRP polymorphism and serum lipid traits yielded some significant race and gender specific significant association for lipoprotein(a) in non-Hispanic White males (P=0.02); HDL2-cholesterol in Hispanic females (P=0.03) and apolipoprotein B in Benin males (P=0.04). We also observed an interaction between the LRP polymorphism and menopausal status for Lp(a) in Hispanic females (P=0.014). However, considering multiple comparisons were performed, these associations could be due to chance. Our data indicate that although the LRP tetranucleotide polymorphism exhibits inter-racial differences in its distribution, it does not appear to have a significant role in affecting serum lipid traits.

Incidence and progression of diabetic retinopathy in Hispanics and non-Hispanic whites with type 2 diabetes. San Luis Valley Diabetes Study, Colorado

OBJECTIVE

To learn if Hispanic people with type 2 diabetes have excess incidence and/or progression of diabetic retinopathy and to explore the association of risk factors with diabetic retinopathy.

RESEARCH DESIGN AND METHODS

There were 244 subjects with type 2 diabetes (65.3% Hispanic) with at least one follow-up visit between 1984 and 1992 examined for the development of retinopathy over a median of 4.8 years (range 2.0-6.6 years). Stereo fundus photos were graded by the University of Wisconsin Reading Center.

RESULTS

Of the 169 subjects without retinopathy at baseline, 47 developed some retinopathy, an incidence rate of 63.7 per 1,000 person-years (PY), or a 4-year cumulative incidence of 22.5%. The Hispanic incidence rate was 58.3/1,000 PY (95% CI: 39.4-83.3), which was lower than among non-Hispanic whites, 76.1/1,000 PY (44.3-121.9). Progression occurred in 24 of the 75 subjects with retinopathy at baseline, a 4-year cumulative rate of 24.1%. Logistic regression showed that insulin treatment was associated with higher risk of any retinopathy (odds ratio [OR] = 8.45, 2.65-26.97), and both systolic blood pressure (odds ratio [OR] = 1.58, 0.99-2.52) and total GHb (OR = 1.46, 0.99-2.17) nearly attained statistical significance. After adjustment for multiple potential risk factors, the Hispanic/non-Hispanic white OR was 0.66 (0.28-1.57).

CONCLUSIONS

No excess risk for incident retinopathy was found among Hispanic compared with non-Hispanic white subjects in this population. These results are consistent with our previously reported prevalence data from the same population but differ from reports of excess prevalence among Texas Hispanics. No other Hispanic incidence data are available to assist in reconciling this difference.

Plasma apolipoprotein A-I, apolipoprotein B, and lipoprotein(a) concentrations in normoglycemic Hispanics and non-Hispanic whites from the San Luis Valley, Colorado

Lower levels of plasma apolipoprotein (apo) A-I and higher levels of apoB, lipoprotein(a) (Lp(a)), and the ratio of apoB to apoA-I are considered to be independent risk factors for coronary heart disease. To examine race differences in the distributions of plasma levels of apoA-I, apoB, and Lp(a), the authors have determined quantitative levels of these traits in 252 nondiabetic Hispanics and 459 nondiabetic non-Hispanic whites (NHWs) from the San Luis Valley, Colorado. Hispanic men and women, respectively, had significantly higher plasma apoB levels (p < 0.003; p < 0.01) and the ratio of apoB to apoA-I (p < 0.003; p < 0.0003) than their NHW counterparts. Plasma Lp(a) concentrations were also significantly higher in Hispanic men (p < 0.003) and apoA-I levels were significantly lower in Hispanic women (p < 0.0003) than NHW men and women, respectively. Overall, the threshold points of apoA-I (< 120 mg/dl), apoB (> 120 mg/dl), and Lp(a) (> 25 mg/dl) were higher in Hispanics than in NHWs for apoA-I (22.8 vs. 15.7%), apoB (16.9 vs. 9.9%), and Lp(a) (18.6 vs. 12.4%). These data suggest that the quantitative risk profile for coronary heart disease with respect to these three quantitative traits is not favorable for Hispanics compared with that for NHWs in the San Luis Valley, Colorado.

Molecular basis of the apolipoprotein H (beta 2-glycoprotein I) protein polymorphism

Apolipoprotein H (apoH, protein; APOH, gene) is considered to be an essential cofactor for the binding of certain antiphospholipid autoantibodies to anionic phospholipids. APOH exhibits a genetically determined structural polymorphism due to the presence of three common alleles (APOH*1, APOH*2 and APOH*3) detectable by isoelectric focusing (IEF) and immunoblotting. The APOH*3 allele can be further characterized into two subtypes, APOH*3w and APOH*3B, based upon its reactivity with monoclonal antibody 3D11. In this study we have determined the molecular basis of the APOH protein polymorphism and its distribution in three large U.S. population samples comprising 661 non-Hispanic whites, 444 Hispanics and 422 blacks. By direct DNA sequencing of PCR amplified fragments corresponding to the eight APOH exons, we identified two missense mutations that correspond to the APOH*1 and APOH*3w alleles. A missense mutation (G-->A) in exon 3, which alters amino acid Ser to Asn at codon 88 and creates a restriction site for TSP509 I, was present in all APOH*1 allele carriers. A second missense mutation (G-->C) at codon 316 in exon 8, which replaces amino acid Trp with Ser and creates a restriction site for BSTBI, was present in all APOH*3w carriers. The distribution of the Ser 88 Asn and Trp 316 Ser mutations was significantly different between the three racial groups. The frequency of the Asn-88 allele was 0.011, 0.043, and 0.056 in blacks. Hispanics and non-Hispanic whites, respectively. While the Ser-316 allele was observed sporadically in blacks (0.008), it was present at a polymorphic frequency in Hispanics (0.027) and non-Hispanic whites (0.059). The identification of the molecular basis of the APOH protein polymorphism will help to elucidate the structural-functional relationship of apoH in the production of antiphospholipid autoantibodies.

High saturated fat and low starch and fibre are associated with hyperinsulinaemia in a non-diabetic population: the San Luis Valley Diabetes Study

A geographically based sample of 1069 Hispanic and non-Hispanic white persons aged 20-74 years, living in southern Colorado and who tested normal on an oral glucose tolerance test (World Health Organization criteria) were evaluated to determine associations of dietary factors with fasting serum insulin concentrations. Subjects were seen for up to three visits from 1984 to 1992. A 24-h diet recall and fasting insulin concentrations were collected at all visits. In longitudinal data analysis, lower age, female gender, Hispanic ethnicity, higher body mass index, higher waist circumference, and no vigorous activity were significantly related to higher fasting insulin concentrations. High total and saturated fat intake were associated with higher fasting insulin concentrations after adjusting for age, sex, ethnicity, body mass index, waist circumference, total energy intake and physical activity. Dietary fibre and starch intake were inversely associated with fasting insulin concentrations. No associations with fasting insulin concentrations were observed for monounsaturated fat, polyunsaturated fat, sucrose, glucose and fructose intake. Associations were similar in men and women and for active and inactive subjects, though associations of fibre and starch intake with insulin concentrations were strongest in lean subjects. These findings support animal studies and a limited number of human population studies which have suggested that increased saturated and total fat intake and decreased fibre and starch intake increase fasting insulin concentrations and may also increase insulin resistance. These findings, which relate habitual macronutrient consumption to hyperinsulinaemia in a large population, may have implications for studies attempting primary prevention of non-insulin-dependent diabetes mellitus.

Predictors of progression from impaired glucose tolerance to NIDDM: an analysis of six prospective studies

Risk factors associated with the progression from impaired glucose tolerance (IGT) to NIDDM were examined in data from six prospective studies. IGT and NIDDM were defined in all studies by World Health Organization (WHO) criteria, and baseline risk factors were measured at the time of first recognition of IGT. The studies varied in size from 177 to 693 participants with IGT, and included men and women followed from 2 to 27 years after the recognition of IGT. Across the six studies, the incidence rate of NIDDM was 57.2/1,000 person-years and ranged from 35.8/1,000 to 87.3/1,000 person-years. Although baseline measures of fasting and 2-h postchallenge glucose levels were both positively associated with NIDDM incidence, incidence rates were sharply higher for those in the top quartile of fasting plasma glucose levels, but increased linearly with increasing 2-h postchallenge glucose quartiles. Incidence rates were higher among the Hispanic, Mexican-American, Pima, and Nauruan populations than among Caucasians. The effect of baseline age on NIDDM incidence rates differed among the studies; the rates did not increase or rose only slightly with increasing baseline age in three of the studies and formed an inverted U in three studies. In all studies, estimates of obesity (including BMI, waist-to-hip ratio, and waist circumference) were positively associated with NIDDM incidence. BMI was associated with NIDDM incidence independently of fasting and 2-h post challenge glucose levels in the combined analysis of all six studies and in three cohorts separately, but not in the three studies with the highest NIDDM incidence rates. Sex and family history of diabetes were generally not related to NIDDM progression. This analysis indicates that persons with IGT are at high risk and that further refinement of risk can be made by other simple measurements. The ability to identify persons at high risk of NIDDM should facilitate clinical trials in diabetes prevention.