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.