Encouraging cycling through a pilot cycling proficiency training program among adults in central Sydney.

In the face of declining population levels of physical activity, programs that encourage cycling represent an under-developed strategy in Australia. In 2003, we implemented a pilot cycling proficiency training (CPT) program for adults in central Sydney, New South Wales. To evaluate the program, participants completed pre- and post-course self-administered questionnaires and participated in a follow-up telephone interview 2 months after their course. Between April and December 2003, 20 CPT courses were conducted. Of 113 people who started a course, 81 (72%) completed at least one course (beginner or intermediate) and 105 (93%) took part in the pre and follow-up interview. Participant satisfaction with all aspects of the course was high. At 2-month follow-up, the course had significantly increased participants' self-reported skills and confidence for cycling. More than half of the participants (56%) said they cycled more 2 months after the course. There was a 40% increase in participants having cycled in the previous week at follow-up among baseline non-cyclists, although this was not statistically significant. There was also a significant increase in weekly participation in other forms of moderate intensity physical activity. Overall, the program was reasonably successful, particularly among those people not cycling at baseline. Cycling proficiency training for adults is one strategy that can supplement other active transport policies to encourage physical activity, although bicycle friendly urban planning and policies are still required to create more supportive environments for cyclists.

The relationship between zinc and copper status and lipid levels in African-Americans.

Studies examining the role of zinc and copper nutriture as risk factors for cardiovascular disease in European Americans have produced conflicting results. This study assessed the associations between zinc and copper status and serum lipid levels in an adult African-American community. A cross-sectional study was conducted on 600 individuals (233 males, 367 females) from 25 to 65 yr of age using a random sampling design in a small city in Alabama. Anthropometric, dietary, and serum zinc, copper, and lipid measurements were made. The mean serum zinc and copper levels and dietary zinc intake were similar to that reported previously for European Americans. There were no significant associations between serum zinc, copper, or zinc/copper ratio and total serum cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), or triglyceride levels. For males, there was a small but significant association between dietary zinc and the total cholesterol/HDL-C ratio (r = -0.17, p = 0.03). Similarly, females taking either zinc supplements or a multivitamin including zinc had higher HDL-C values than nonsupplementing females. Further prospective studies of the relationship between zinc status and lipid levels in African Americans are needed to verify these results.

John Henryism, gender, and arterial blood pressure in an African American community.

OBJECTIVE: To examine the interaction between gender and John Henryism in relationship to arterial blood pressure in an African American community in the Southern United States. It was hypothesized that, within this specific social and cultural context, John Henryism would be associated with blood pressure differently for men and women. METHODS: A cross-sectional survey of 600 persons, aged 25 to 65, was conducted in the African American community of a small Southern city. John Henryism was assessed using the 12-item John Henryism Scale for Active Coping. Blood pressure was assessed by conventional methods. RESULTS: The interaction effect between gender and John Henryism was assessed as a cross-product term in ordinary least squares regression analysis using arterial blood pressure as the dependent variable, and with logistic regression using hypertension as the dependent variable. This interaction effect was significant (p < .05) in relation to systolic blood pressure and hypertension, with the effect evident (p < .07) in relation to diastolic blood pressure. For men, as John Henryism increases, blood pressure and the risk of hypertension increases. For women, as John Henryism increases, blood pressure and the risk of hypertension decreases. CONCLUSIONS: The association of the behavioral disposition of John Henryism with blood pressure is dependent on the gender of the individual. Men and women face differing cultural expectations and social structural constraints in this community. The sociocultural context modifies the meaning of the behavioral disposition, and hence its effects.

Culture, socioeconomic status, and coronary heart disease risk factors in an African American community.

In this paper, cultural influences are examined in the relationship between socioeconomic status and health. Cultural definitions of material lifestyles are investigated as a correlate of disease risk in an African American community in the rural South. A new technique--called "cultural consensus analysis"--is used to test for a cultural model of lifestyles indicative of success. Survey data are then used to operationalize the degree to which individuals adhere in their own behavior to that cultural model; this measure is referred to as "cultural consonance in lifestyle." Cultural consonance in lifestyle is more strongly associated with hypertension and smoking (but not serum lipids) than are conventional measures of socioeconomic status (occupation, income, and education). These results suggest that the extent to which individuals are unable to live in accordance with cultural norms regarding lifestyles may contribute to the risk of coronary heart disease in the African American community.

Bergmann's rule and the thrifty genotype.

One of Roberts' key contributions was his work demonstrating the applicability of several ecological rules to human populations (Roberts [1953] Am. J. Phys. Anthropol. 11:533-558; [1978] Climate and Human Variability, 2nd ed., Menlo Park, CA: Cummings). His finding that average body weight systematically covaries with mean annual temperature was widely taken as confirmation of Bergmann's rule for humans. More recently his findings on weight and temperature have been extended and confirmed (Ruff [1994] Yrbk. Phys. Anthropol. 37:65-407; Katzmarzyk and Leonard [1995] Hum Biol Council Program Abstracts 132) although the strength of the association may be decreasing when considering more recent surveys (Katzmarzyk and Leonard [1995]). Roberts noted in 1953 that Oceanic populations may be somewhat of an exception to Bergmann's rule, and we propose that Neel's ([1962] Am. J. Hum. Genet. 14:353-362) thrifty genotype model may account for some of the deviation from predicted weights among these populations. We provide an updated version of the thrifty genotype model, suggesting that selection for energetic efficiency may have occurred for some Oceanic populations during the voyaging to and settlement of their island homes. Under conditions of modernization the thrifty genotype may be manifesting as high rates of obesity and NIDDM among Polynesians and Micronesians. First, using measurements of adult male weight from 19 Oceanic populations, we demonstrate the extreme nature of their deviation from predicted weight based on Roberts' regression of weight on mean annual temperature. Next, we regress the deviations from predicted weight on NIDDM prevalence for these 19 populations, producing a highly significant regression (R2 = 0.46; P < 0.001), consistent with expectations if the thrifty genotype is responsible for the high weights.

Social context and psychosocial influences on blood pressure among American Samoans.

This study explores social and explores social and economic influences on health within a model formulated to address explicitly both individual and household level phenomena. Dressler's lifestyle incongruity model is used as a basis from which to predict the effects of intracultural contexts of variability on blood pressure. The sample for this survey consists of 134 Samoan men and women living in American Samoa. Based on previous experience and ethnographic sources, two key intracultural contexts were examined; gender, i.e., male-female differences in response to psychosocial stress, and household employment as indicated by whether or not both spouses in a household are employed. Our analysis indicates that lifestyle incongruity, defined as the difference between the material culture presented by a household and the economic resources of the family, is significantly associated with both systolic and diastolic blood pressure. Furthermore, males and females show opposite blood pressure associations with both lifestyle incongruity (male blood pressure increases with increasing incongruity while female blood pressure does not) and household employment (male blood pressure is higher when both spouses work but female blood pressure is lower).

Social status, social context, and arterial blood pressure.

As social change and economic development have proceeded, the prevalence of chronic diseases, especially cardiovascular diseases, has increased in the developing world. In part this is due to the adoption of diets and other health behaviors characteristics of industrialized nations; in part it is a function of changing social and economic circumstances. In this paper, we describe the development and testing of a model designed to account for social and economic effects on cardiovascular disease risk. The model incorporates the fact that global economic processes have made a lifestyle characterized by the consumption of Euroamerican material goods and information a basis for the assignment of social status in local communities. But economic change at the local level is rarely sufficient to provide a foundation for individuals' status aspirations. Hence, many individuals attempt to maintain lifestyle inconsistent with their economic standing, a variable we term lifestyle incongruity. Here we described how this factor is associated with higher blood pressure in a variety of settings and also how the effects of lifestyle incongruity can be modified in local contexts by social class and social role processes. This latter process, contextual modification, is illustrated by data from American Samoa. In this example, the association of lifestyle incongruity with blood pressure is examined in 30 male household heads and 26 spouses. After an examination of Samoan ethnography focused attention on the importance of age and gender differences as defining social contexts of intracultural variation, the model was modified to assess interactions between age and gender as they affect the association of lifestyle incongruity and blood pressure. Lifestyle incongruity is strongly associated with higher systolic and diastolic blood pressure for the younger household heads, minimally associated with blood pressure for older household heads, and only slightly associated with blood pressure of their spouses. The regression coefficients for the lifestyle incongruity by age by sex interaction term was significant at P < or = 0.01 for both systolic and diastolic blood pressure. The consistency of these results with expectations based on the ethnographic record is emphasized in the interpretation. We feel that the lifestyle incongruity model represents and empirically successful attempt to link global political-economic processes, local social structure, and biological outcomes.

Sociocultural and behavioral influences on health status among the Mississippi Choctaw.

Native American populations in North America are at increased risk of a variety of health problems, including (but not limited to) diabetes. This risk is presumed to be a result of the interaction of environmental influences with a population genetic susceptibility. Anthropologists have subsumed those environmental influences under the term "acculturation." Here, we break that broad concept into physical, behavioral, and sociocultural components in an examination of the correlates of arterial blood pressure and plasma glucose among the Mississippi Choctaw. In a sample of 93 adults, higher plasma glucose was associated with the lower physical activity, higher body mass index, and higher lifestyle incongruity, after controlling for age, sex, and recency of food consumption. Higher arterial blood pressure was associated with higher body mass index and being single. These results suggest that the risk of disordered glucose metabolism within this Native American population is associated with acculturation broadly construed, but that refined models of health and disease must take into account the multiple dimensions of this concept. Physical, behavioral, and sociocultural factors combine to describe more precisely the concept of acculturation, and hence the factors contributing to the risk of disease in Native American communities.

Genetic studies of human apolipoproteins. XVII: Population genetics of apolipoprotein polymorphisms in American Samoa.

Variation in human apolipoprotein genes is a major source of phenotypic differences in human lipid metabolism. Data regarding genetic variation at apolipoprotein loci in various populations are only beginning to accumulate, and they suggest that different populations vary widely in distribution of apolipoprotein alleles. Using isoelectric focusing-immunoblotting techniques, we screened 67 serum samples from self-identified Samoan residents of American Samoa to investigate structural variation at six apolipoprotein loci: A-I, A-II, A-IV, C-II, E, and H. The APO A-I, A-II, and C-II loci were found to be monomorphic by isoelectrical focusing. In Samoans, the common three-allele polymorphism was observed for APO E, with no striking differences in frequencies from Caucasian populations. The three common alleles of the APO H locus also were identified; however, frequencies of the less common alleles (APO H*I and APO H*3) were different from those observed elsewhere for Caucasians.

Ethnicity as a taxonomic tool in biomedical and biosocial research.

Ethnicity and race are commonly used in biomedical research to portion human populations into groups for analysis. The view taken here is that race is a sociological construct that is poorly correlated with any measurable biological or cultural phenomenon other than the amount of melanin in an individual's skin. On the other hand, ethnicity is a sociocultural construct that is often, if not always, coextensive with discernible features of a group of individuals. These features include, but need not be limited to, language, style of dress and adornment, religion, patterns of social interaction, and food habits. The purpose of this brief commentary is to examine definitional issues surrounding use of the term ethnicity, to review the use of ethnicity in biomedical and biosocial research, and to examine the ecological and evolutionary basis for ethnic differentiation in the human population. Its purpose is not to provide a final definition of ethnicity, but instead to suggest that ethnicity is a multiplex concept that has a variety of applications and definitions, each perhaps dependent upon particular research problems and situations. We suggest that individual researchers explicitly state how they are using ethnicity, what their chosen categories imply biologically and sociologically, and why their particular analyses are needed. This may help to limit conflicts that arise over the inappropriate use of ethnicity in biomedical and biocultural research.

Growth patterns of height and weight among three groups of Samoan preadolescents.

The Samoan population affords an excellent opportunity to study the influences of modernization and migration on growth. Moreover, since Samoan adults in some settings have very high rates of obesity, the childhood precursors to obesity can be studied among Samoans. This study reports the results of a survey of 786 Samoan children between 5.5 and 11.5 years of age living in traditional, modern or migrant situations. It was found that the children from Western Samoa (traditional) were significantly shorter, lighter and lighter for height than their counterparts in American Samoa (modern) and Hawaii (migrant). The major influence on height and weight appears to be modernization (Western versus American Samoa), with migration (American Samoa versus Hawaii) playing only a small incremental role (significant only for weight among boys). The influences of modernization are likely to be exerted through changes in diet and activity among the children. Modernization and migration are associated with obesity among Samoan adults, and this pattern also seems to be established in preadolescents.

Modernization, migration and obesity among Samoan adults.

Modernization and migration have biological as well as social effects on people. In this study, 2657 Samoan adults from Western Samoa, American Samoa and Hawaii were surveyed in an attempt to examine the relationships between modernization, migration and obesity. The Samoan men showed an increase in the frequency of obesity with increasing modernity of residence or occupation. While the women in American Samoa had the highest frequency of obesity of any subsample, Samoan women also demonstrated a pattern of higher adiposity in more modern jobs. Young women tended to show a negative relationship between obesity frequency and education, with college-educated women having the lowest average levels of adiposity. Time since migration to Hawaii was not found to exert a major effect on frequency of obesity.

The influence of infant feeding patterns on growth of children in American Samoa.

PIP: This paper examines the trends in infant feeding practices in American Samoa and analyzes the relationship between infant feeding and growth among children born in American Samoa from 1976 to 1982. The study population is composed of the Polynesian inhabitants of the islands comprising the Territory of American Samoa. The sample is drawn from the records of the Well Baby Clinic in American Samoa. Feeding habit information and health of the infant was solicited by the nurses and doctor during clinic visits. The mothers were questioned about the child's diet. About 40% of the infants were exclusively breastfed; 13% had bottle supplements; 6% were classified as milk drinkers; and 40% were formula-fed. Frequently more than 1 feeding pattern was noted for a given child. Feeding influences were found to be significant on weight up to age 4, and height up to age 3. The timing of the introduction of solids was found to have a significant relationship with length through age 2. There appears to be a complex set of interactions between socioeconomic, growth and health factors. Mothers wean children early to return of work. This results from the availability of infant formula in Samoan stores, more jobs for women and the desire to improve socioeconomic status. Bottlefed infants of working mothers are more likely to have gastrointestinal problems than other infants. As a group, however, bottlefed infants are likely to have higher weights. The most significant contributing factor to morbidity and mortality among adults in American Samoa is the high prevalence of obesity. Extended breastfeeding of the infant can promote health in infancy and in later years.^ieng

The body build and composition of Samoan children: relationships to infant feeding patterns and infant weight-for-length status.

The relationships between infant feeding patterns, infant weight status, and subsequent growth are not yet firmly established. This study attempts to address these topics among Samoan children. The study population consists of 1,186 children born between October 1974 and September 1976 who were subsequently seen in the Well Baby Clinic in American Samoa. On the basis of the clinic records the children were categorized into feeding groups (breast vs. bottle) and weight-for-length groups (less than 25th percentile or greater than 75th percentile of National Center for Health Statistics ( NCHS ) standards). A survey of 74 of these children was conducted in 1982. The average age of the children was 6.6 years. Twenty anthropometric measurements were taken and divided into three groups: skeletal, adipose, and mixed. Multiple analysis of variance was used on each of the groups of measurements to assess effects of infant feeding and weight-for-length. This analysis demonstrated significant relationships between infant weight-for-length and childhood skeletal size (heavy infants are larger children); between infant feeding patterns and childhood adiposity (bottle-fed children are fatter); and between both infant patterns and the mixed measurements (heavy and bottle-fed infants are heavier children with larger circumferences). The relationship between infant weight-for-length and skeletal size may be a continuation of infant patterns of high musculoskeletal weight in heavy infants. The relationship between infant feeding and childhood fatness was not affected by family income.

PIP: The relationships between infant feeding patterns, infant weight status, and subsequent growth are not yet firmly established. This study attempts to address these topics among Samoan children. The study population consists of 1186 children born between October 1974 and September 1976 who were subsequently seen in the Well Baby Clinic in American Samoa. On the basis of the clinic records the children were categorized into feeding groups (breast vs. bottle) and weight-for-length groups (less than 25th percentile or greater than 75th percentile of National Center for Health Statistics (NCHS) standards). A survey of 74 of these children was conducted in 1982. The average age of the children was 6.6 years. 20 anthropometric measurements were taken and divided into 3 groups: skeletal, adipose, and mixed. Multiple analysis of variance was used on each of the groups of measurements to assess effects of infant feeding and weight-for-length. This analysis demonstrated significant relationships between infant weight-for-length and childhood skeletal size (heavy infants are larger children); between infant feeding patterns and childhood adiposity (bottle-fed children are fatter); and between both infant patterns and the mixed measurements (heavy and bottle-fed infants are heavier children with larger circumferences). The relationship between infant weight-for-length and skeletal size may be a continuation of infant patterns of high musculoskeletal weight in heavy infants. The relationship between infant feeding and childhood fatness was not affected by family income.

Marijuana smoking and cold tolerance in man.

Ten men who were marijuana users served as subjects in a study of the effects of marijuana smoking on response to cold. Cold water (28 degrees C for 60 min) and cold air (20 degrees C for 120 min) mediums were utilized with three exposures in each medium. The three exposures followed smoking marijuana, smoking placebo, and a no-smoking control period. Additionally, a breathhold experiment preceded and followed the four smoking periods. Marijuana and placebo smoke were inhaled from a spirometer with each man receiving the smoke of 0.739 g of marijuana and placebo. Smoking marijuana did not greatly modify body heat content, since rectal temperature and most peripheral temperatures were not altered. However, temperatures over voluntary muscles likely to be involved in shivering were elevated. Heat production also greatly increased after marijuana, suggesting that it had stimulated shivering. Marijuana also produced tachycardia and abolished apneic bradycardia. The mechanism of this action is not clear, but some sympathetic involvement is indicated.