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Biomedical subjects

Henrik B Rasmussen

Publications and source records attributed to Henrik B Rasmussen.

6 recordsLinked to original sources
PubMed2007

Cognitive performance in elderly women: significance of the 19bp insertion/deletion polymorphism in the 5' flank of the dopamine beta-hydroxylase gene, educational level, body fat measures, serum triglyceride, alcohol consumption and age.

BACKGROUND: Genetic and environmental factors influence cognitive aging. The gene encoding dopamine beta-hydroxylase (DBH) could be one such factor since this hydroxylase converts dopamine to norepinephrine both of which are involved in cognition regulation. OBJECTIVE: To assess the effect of the 19bp insertion/deletion polymorphism in the 5' flank of the DBH gene on cognitive performance in elderly women relative to other factors of cognitive aging. METHODS: We examined a cross-sectional sample of 1371 postmenopausal women. Cognitive abilities were assessed by the 6-item orientation-memory-concentration test. The 19bp insertion/deletion polymorphism of the DBH gene was genotyped and apolipoprotein E (APOE) epsilon4 allele status was determined. In addition blood pressure, body fat mass and blood lipids were measured. Information was also obtained by personal interviews. Data were analyzed by regression analysis. RESULTS: Cognition was univariately associated with DBH genotype (p = 0.04). A univariate association of borderline significance was observed for APOE epsilon4 allele status (p = 0.07). Exclusion of women with severe cognition impairment did not alter the strength of the association with the DBH gene polymorphism markedly (p = 0.06) but obliterated the weak association between APOE epsilon4 allele status and cognition. The association of the DBH gene polymorphism with cognition persisted after adjustment for other variables (p = 0.03). CONCLUSIONS: The 19bp insertion/deletion polymorphism of the DBH gene influences cognition in elderly women and might have a stronger effect than APOE epsilon4 allele status on mild cognitive impairment. Both genetic polymorphisms had a significantly smaller impact on cognition than age, education, alcohol consumption and body fat measures.

5' Untranslated Regions↗
PubMed2006

Stable isotopes in elephant hair document migration patterns and diet changes.

We use chronologies of stable isotopes measured from elephant (Loxodonta africana) hair to determine migration patterns and seasonal diet changes in elephants in and near Samburu National Reserve in northern Kenya. Stable carbon isotopes record diet changes, principally enabling differentiation between browse and tropical grasses, which use the C3 and C4 photosynthetic pathways, respectively; stable nitrogen isotopes record regional patterns related to aridity, offering insight into localized ranging behavior. Isotopically identified range shifts were corroborated by global positioning system radio tracking data of the studied individuals. Comparison of the stable isotope record in the hair of one migrant individual with that of a resident population shows important differences in feeding and ranging behavior over time. Our analysis indicates that differences are the result of excursions into mesic environments coupled with intermittent crop raiding by the migrant individual. Variation in diet, quantified by using stable isotopes, can offer insight into diet-related wildlife behavior.

Animal Migration↗
PubMed2006

Estrogen receptor alpha and risk for cognitive impairment in postmenopausal women.

The estrogen receptor alpha (ESR1) gene has been implicated in the process of cognitive impairment in elderly women. In a paired case-control study, we tested whether two ESR1 gene polymorphisms (the XbaI and PvuII sites) are risk factors for cognitive impairment as measured by the six-item Orientation-Memory-Concentration test in postmenopausal Danish women. Hormone replacement therapy, age and executive cognitive ability were examined as covariates for ESR1 gene effects on cognitive impairment. The XbaI polymorphism showed a marginal effect on cognitive abilities (P=0.054) when adjusted for executive cognitive ability. Using a dominant genetic model for the X allele, we found an elevated risk (executive cognitive ability adjusted P=0.033) for cognitive impairment. Hormone replacement therapy also had a borderline effect on cognitive ability (P=0.049) and this effect was reflected in executive cognitive ability. These data support that the ESR1 gene variants affect cognitive functioning in postmenopausal women.

Aged↗
PubMed2005

Serotonin transporter: evolution and impact of polymorphic transcriptional regulation.

The serotonin transporter (SERT) is the primary drug target in the current antidepressant therapy. A functional polymorphism in the 2nd intron of the 5HTT gene encoding the SERT has been identified and associated with susceptibility to affective disorders and treatment response to antidepressants. This study addresses the possible impact of the variable number of tandem repeats (VNTR) to behavior and disease by examining the evolutionary origin and mechanisms of differential transcriptional regulation of SERT. We trace the evolutionary origin of the VNTR and show that it is present and varies extensively across the great apes and monkeys as well as in rodents while it is absent in non-mammals. As in humans, the VNTR sequence may be polymorphic within species and thus it may underlie both inter- and intraspecies differences. Also, we find new putative binding sites for several transcription factors in the VNTRs of all mammalian SERT genes. The number of these putative binding sites varies proportionally to the length of the VNTR. We propose that the intronic VNTR have been selectively targeted through mammalian evolution to finetune transcriptional regulation of the serotonin expression.

Amino Acid Sequence↗
PubMed2005

The sexually active states of free-ranging male African elephants (Loxodonta africana): defining musth and non-musth using endocrinology, physical signals, and behavior.

Musth in male African elephants, Loxodonta africana, is associated with increased aggressive behavior, continuous discharge of urine, copious secretions from the swollen temporal glands, and elevated androgen levels. During musth, bulls actively seek out and are preferred by estrous females although sexual activity is not restricted to the musth condition. The present study combines recently established methods of fecal hormone analysis with long-term observations on male-female associations as well as the presence and intensity of physical signals to provide a more detailed picture about the physical, physiological, and behavioral characteristics of different states of sexual activity in free-ranging African elephants. Based on quantitative shifts in individual bull association patterns, the presence of different physical signals, and significant differences in androgen levels, a total of three potential sub-categories for sexually active bulls could be established. The results demonstrate that elevations in androgen levels are only observed in sexually active animals showing temporal gland secretion and/or urine dribbling, but are not related to the age of the individual. Further, none of the sexually active states showed elevated glucocorticoid output indicating that musth does not represent an HPA-mediated stress condition. On the basis of these results, we suggest that the term "musth" should be exclusively used for the competitive state in sexually active male elephants and that the presence of urine dribbling should be the physical signal used for defining this state.

Age Factors↗