K. Christensen

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Old-age survival has increased substantially since 1950. Death rates decelerate with age for insects, worms, and yeast, as well as humans. This evidence of extended postreproductive survival is puzzling. Three biodemographic insights--concerning the correlation of death rates across age, individual differences in survival chances, and induced alterations in(More)
OBJECTIVES To study the relative influence of genetic and environmental factors on self-rated health and hospitalization patterns in the elderly. METHODS A survey among all 3,099 Danish twins ages 75 years and older identified in the Danish Twin Registry. An interview was conducted with 77% of the twins. The number of hospitalizations in the previous 18(More)
We have generated RANK (receptor activator of NF-kappaB) nullizygous mice to determine the molecular genetic interactions between osteoprotegerin, osteoprotegerin ligand, and RANK during bone resorption and remodeling processes. RANK(-/-) mice lack osteoclasts and have a profound defect in bone resorption and remodeling and in the development of the(More)
MSX1 has been proposed as a gene in which mutations may contribute to non-syndromic forms of cleft lip and/or cleft palate. Support for this comes from human linkage and linkage disequilibrium studies, chromosomal deletions resulting in haploinsufficiency, a large family with a stop codon mutation that includes clefting as a phenotype, and the Msx1(More)
Sharing of intrauterine environment in twins of opposite sex has been hypothesized to result in masculinization of the female twin. We tested this hypothesis by comparing strength (maximum hand-grip pressure) and various anthropometric measures in a newly established survey panel comprising 4,314 middle-aged twins identified through a Danish(More)
The antioxidant enzyme paraoxonase 1 (PON1) has previously been suggested to confer protection against coronary heart disease (CHD), one of the main causes of death in the Western world. Two coding polymorphisms, 55M/L and 192Q/R, and a promoter variant, -107C/T, has been extensively studied with respect to susceptibility to CHD. In this study, we have(More)
* This material is based upon work supported by the National Science Foundation under Grant No. 9875177. Abstract Input buffered switches with Virtual Output Queues (VOQ) are scalable to very high speeds, but require switch matrix scheduling algorithms to achieve high throughput. Existing scheduling algorithms based on parallel requestgrant-accept cycles(More)
OBJECTIVE To test the validity of the fetal origins hypothesis and the classic twin method. DESIGN Follow up study of pairs of same sex twins in which both twins survived to age 6. SETTING Denmark. SUBJECTS 8495 twin individuals born 1870-1900, followed through to 31 December 1991. MAIN OUTCOME MEASURES Mortality calculated on a cohort basis. (More)
Heritable influences on cognitive functioning were investigated in a sample of 403 pairs of like-sex Danish twins aged 75 years and older. Twins completed the Mini-Mental State Examination and 3 other cognitive tests. Genetic factors accounted for 26-54% of the variance on these measures, with the balance being due to environmental factors that create(More)
OBJECTIVES The authors studied nonagenarians, a rapidly growing age group whose cognitive and physical abilities have yet to be investigated systematically. METHODS All Danes born in 1905 were invited to participate in a home-based 2-hour multidimensional interview, including cognitive and physical performance tests and collection of DNA, carried out by(More)