PubMed Health⌕ Search

Biomedical subjects

Douglas E Crews

Publications and source records attributed to Douglas E Crews.

9 recordsLinked to original sources
PubMed2006

Parental investment, late reproduction, and increased reserve capacity are associated with longevity in humans.

Throughout the living world trade-offs between reproductive success and longevity have been observed. In general, two extremes of life history patterning are reported, r- and K-selected species. The latter tend toward larger body sizes, few offspring from any one pregnancy, few offspring over the female reproductive span, longer life spans, and greater parental investment (PI: all efforts and expenses associated with the production, gestation, post-natal care, feeding, and protection of young) (e.g., whales, elephants, hominids). r-selected species tend toward smaller body size, multiple births/litters per pregnancy, female production of many gametes and offspring over the life span, and low levels of PI (e.g., most plants, insects, mice). These differences have significant influences on physiological variation among human populations. Across human samples, reproductive success (RS: the number of offspring successfully birthed and reared to reproductive age) has been reported to vary positively, negatively, and not at all with longevity of women. This complexity may be in part due to the fact that both early-life and late-life fecundity are associated with longevity in women, while total parity seems a poor gauge of female longevity in humankind. Large variations in associations of RS with longevity in women suggest that multiple factors may confound this association. One confounding factor is that among women, RS is largely determined not by fecundity, but by the quality of PI available to offspring. Among modern humans, PI is more complex, longer lasting (both relatively and absolutely), and extensive than for any other mammal. This suggests that modern human life history is a reflection of the co-evolution of longevity and extensive PI as part of our species' biocultural evolution. The need for long-term PI has greatly shaped human physiological variation and patterns of longevity.

Adolescent↗
PubMed2006

Aging, disability, and frailty: implications for universal design.

Throughout the world all populations are seeing burgeoning numbers of "elders", defined as persons aged 65 year and older. In many countries, including Japan, the United States, Norway, Sweden and the United Kingdom, those aged over 65 are at or approaching 15% of the population. As their numbers have increased, so have their health care expenses, leading to extensive research on the health, well being, and life expectancy of these increasingly older elders. Today this group is further sub-divided: the young-old ages 65-74, the old-old ages 75-84, and the oldest-old ages 85+, for both health care and research purposes. However broad variation still characterizes even these groupings. Rates of frailty and disability increase with increasing age among these elders. For example, inabilities to complete at least one activity of daily living increased from about 5-7% at ages 65-69 years to about 28-36% at ages 85+ in 1987. Death rates continue to decline at all ages past 50 years and rates of disability seem to be doing the same. For the foreseeable future, we may expect increasing numbers of older, frail elders than in previous decades. Thus, people are not only living longer, they generally are healthier at advanced ages than were previous cohorts, thus "old age" disabilities of the 20th century will be put off to even older ages during the 21st century. As yet there is no clear way to assess senescent changes in humans, although activities of daily living, allostatic load, and frailty indices have all been suggested. One future need is greater development and use of universal and accessible design in all aspects of the built environment.

Activities of Daily Living↗
PubMed2005

Artificial environments and an aging population: designing for age-related functional losses.

Over the past century there has been a large and continuing increase in the frequency of persons aged over 65 years; particularly those aged over 100 years. During the 21st century the number of persons over 100 years will continue to increase. This will occur at such a rapid rate that the 21st century may one day be called the century of centenarians. Frailty and disability secondary to senescence, disease, and trauma have accompanied old age (often defined as age 65 and over) as far back as recorded history. However, during the 20th century, age, frailty, disability, and chronic degenerative diseases have been decoupled to some extant in the most long-lived human populations. Until recently, there was little need to design artificial environments for the unique needs of the elderly due to their low representation in most national populations. Today that need is increasing in concert with the number of persons aged 65 and older. The purpose of this review is to suggest areas wherein physiological anthropologists may have an opportunity to contribute to design trends for this rapidly increasing aging population. Major considerations for design of environments for the elderly are based upon altering the environment to accommodate their declining visual, auditory, and kinesthetic senses, thereby enhancing their declining faculties and improving their autonomy, independence, and self perceptions of well-being. To date most design considerations have been directed toward improving environments for those suffering from Alzheimer's disease or residing within assisted living facilities. Many such design improvements also may be effective in improving life satisfaction and functional abilities of the non-institutionalized elderly.

Activities of Daily Living↗
PubMed2004

Population genetics of apolipoproteins A-IV, E, and H, and the angiotensin converting enzyme (ACE): associations with lipids, and apolipoprotein levels in American Samoans.

Distributions of alleles at three apolipoprotein loci (APO E, APO H, and APO A-IV) and an insertion/deletion (I/D) polymorphism at the angiotensin converting enzyme (ACE) locus among 274 American Samoans are described here. Genotypes at each locus are examined for associations with quantitative lipid (total cholesterol (total-c), LDL-cholesterol (LDL-c), HDL-cholesterol (HDL-c), and triglycerides) and apolipoprotein (APO AI, APO AII, APO E, and APO B) levels. Genotype frequencies at all four loci are in Hardy-Weinberg equilibrium. The most common APO A-IV genotype (1-1) was observed in 252 American Samoans (97%). The three most common APO E genotypes were 3-3 (47%), 3-4 (30%), and 2-3 (12%). The most frequent APO H genotype was 2-2 (86%). The most common ACE genotype (I/I) was observed in 75% of sampled individuals, and 23% were I/D heterozygotes. APO E genotypic variation was associated with total-c, HDL-c, LDL-c, and all four quantitative apolipoproteins (AI, AII, E, and B). APO A-IV genotypes were associated significantly with total cholesterol, LDL-c, and APO-B levels. APO H showed little association with any quantitative lipid or apolipoprotein. ACE D/D homozygotes had higher AII levels. ACE showed a consistent association with APO AII levels, with either APO A-IV or APO E as a covariate. The interaction term between ACE and APO E was also significantly associated with total-c and APO E levels, and the ACE genotype showed a significant main effect on APO AI levels in multivariate analyses.

American Samoa↗
PubMed2003

Reconstructing life history of hominids and humans.

Aspects of life history, such as processes and timing of development, age at maturation, and life span are consistently associated with one another across the animal kingdom. Species that develop rapidly tend to mature and reproduce early, have many offspring, and exhibit shorter life spans (r-selection) than those that develop slowly, have extended periods of premature growth, mature later in life, reproduce later and less frequently, have few offspring and/or single births, and exhibit extended life spans (K-selection). In general, primates are among the most K-selected of species. A suite of highly derived life history traits characterizes humans. Among these are physically immature neonates, slowed somatic development both in utero and post-natally, late attainment of reproductive maturity and first birth, and extended post-mature survival. Exactly when, why, and through what types of evolutionary interactions this suite arose is currently the subject of much conjecture and debate. Humankind's biocultural adaptations have helped to structure human life history evolution in unique ways not seen in other animal species. Among all species, life history traits may respond rapidly to alterations in selective pressures through hormonal processes. Selective pressures on life history likely varied widely among hominids and humans over their evolutionary history. This suggests that current patterns of human growth, development, maturation, reproduction, and post-mature survival may be of recent genesis, rather then long-standing adaptations. Thus, life history patterns observed among contemporary human and chimpanzee populations may provide little insight to those that existed earlier in hominid/human evolution.

Adaptation, Physiological↗
PubMed2003

Blood pressure variation in the institutionalized elderly.

Ambulatory blood pressure (ABP) monitoring has been used to examine stress responses in a variety of settings and populations, demonstrating that both the environment and activities influence BP. Little is known, however, about the effects of such factors on the BP of elders, particularly those in institutional settings. This paper examines sources of variation in BP among elders living in two long-term care settings. Twenty-seven residents of a nursing home (NH) facility and 29 residents from independent living (IL) facilities wore ABP monitors for approximately 24-hours. Individual pressures were transformed to z-scores and analyzed by ANOVA. Posture, mood and activity were significantly associated with systolic BP among IL while location and activity were significantly associated among NH. Posture and activity were associated with diastolic BP among IL residents. The specific effects of location, posture, and activity did not differ across settings.

Affect↗
PubMed2002

Diurnal blood pressure patterns in long-term care settings.

BACKGROUND: Some research suggests that individuals whose blood pressure does not decline at night may be at increased risk of end-organ damage. Few studies have examined ambulatory blood pressure among elders, particularly those living in institutions. This study therefore evaluates ambulatory blood pressure variation in two groups of institutionalized elderly, independent living and nursing home residents. It was suggested that the nursing home sample would have a higher rate of non-dipping than the independent-living residents. DESIGN AND METHODS: Twenty-seven residents (aged 87 +/- 8 years) of a nursing home facility and 29 residents (aged 80 +/- 6 years) from two independent living facilities wore ambulatory monitors for approximately 24 h. Several definitions of dipping were examined. RESULTS: Neither mean daytime nor mean night-time systolic blood pressure differed between the two groups. Daytime diastolic blood pressure was significantly higher in the independent living sample, as was night-time diastolic pressure in the nursing home residents. Neither asleep nor awake blood pressure varied significantly between groups. The decline in night-time blood pressure and sleep blood pressure was significantly greater among the independent living residents (P < 0.05). Ratios of night-time/daytime and asleep/awake blood pressure were significantly higher in the nursing home group. Non-dippers were significantly more frequent among the nursing home residents. CONCLUSIONS: Nursing home residents were significantly more likely to be non-dippers. Both groups of resident were more frequently non-dippers than were individuals in community-dwelling samples. The high prevalence of non-dipping among institutionalized elderly people may be a result of age, health status or institutional activity patterns.

Aged↗
PubMedDate not supplied

Length of marriage and its effect on spousal concordance in Kuwait.

It was hypothesized that marriage duration affects physical and cultural homogamy and spousal concordance in Kuwaiti marriages. Westernization increased spousal correlations due to fewer arranged marriages and increased individual spousal choice. Spousal similarities for selected physical and cultural traits were also examined for couples married 15 years or less, 16 to 30 years, and 31 years and more. Consanguineous couples belong to the al-Kandari, one of the largest and most important kindreds in Kuwait, who traditionally married kin and continue to do so. Six physical measurements and blood pressure were taken along with a sociocultural questionnaire to examine cultural preferences. In all, 242 couples (484 people) participated; 62 couples were in non-consanguineous unions. It was hypothesized that in shorter-duration unions spouses would be more alike for physical and cultural traits. For physical traits, results for stature, weight, the body mass index, and hip circumference are congruent with the hypothesis, whereas results for the triceps and subscapular skinfolds, waist circumference, and systolic and diastolic blood pressure are not. Overall, for some traits spouses are more alike than in previous generations, and specific aspects of similarity among long-term spouses reflect historical and cultural phenomena.

Adult↗