Biomedical subjects

Jan Born

Publications and source records attributed to Jan Born.

22 records · Page 2Linked to original sources

PubMed2002

Vascular endothelial growth factor: a novel endocrine defensive response to hypoglycemia.

Glucose, the most important fuel for the brain, is supplied by the actions of counterregulatory hormones and the sympathetic nervous system. Yet to obtain access to the brain, glucose must pass the blood-brain barrier. Here we show that vascular endothelial growth factor (VEGF), a potent regulator of blood vessel function, is a candidate hormone for facilitating glucose passage across the blood-brain barrier under critical conditions. In 16 healthy men, VEGF serum concentrations increased under 6 h of insulin-induced hypoglycemic conditions from 86.1 +/- 13.4 to 211.6 +/- 40.8 pg/ml (P = 0.002), whereas in the hyperinsulinemic euglycemic control condition, no change was observed. During hypoglycemia serum VEGF, but no other counterregulatory hormone, was associated with preserved neurocognitive function, as measured with a memory test (r = 0.539; P = 0.031) and the Stroop interference task (r = 0.569; P = 0.021). Findings show that acute hypoglycemia is accompanied by a brisk increase in circulating VEGF concentration and that VEGF could mediate rapid adaptation of the brain to neuroglycopenia.

Adult↗

PubMed2002

Food deprivation fails to affect preoccupation with thoughts of food in anorectic patients.

OBJECTIVES: Memory for food words was used to investigate effects of hunger and satiety on information processing in acute and recovered anorectics. DESIGN: In Expt 1, recall of words related to food and unrelated to food was compared between anorectics and controls. In Expt 2, the same procedure was undertaken in recovered anorectics and controls. METHODS: Tests were performed in each subject after starvation and after food intake. RESULTS: When hungry, recall of food words did not differ between anorectics and controls. During satiety, however, anorectics recalled significantly more food words than controls. Recall of food unrelated words did not differ between both groups. Recall in recovered anorectics was comparable with that in acute anorectics. CONCLUSIONS: Results indicate that cognitive processing of food stimuli does not depend on food deprivation in anorectics.

Acute Disease↗

PubMed2000

The neuroendocrine recovery function of sleep.

The hypothalamo-pituitary-adrenal (HPA) system is a most important mediator of the organism's response to stress. Secretory activity of this endocrine system displays a specific regulation during normal nocturnal sleep in humans. Pituitary release of adrenocorticotropin (ACTH) as well as adrenocortical release of cortisol decreases to a minimum during early sleep which is simultaneously characterized by maximum release of growth hormone (GH) and a predominance of slow wave sleep (SWS). In contrast, release of ACTH and cortisol reaches a maximum during late sleep which is simultaneously characterized by minimum plasma concentrations of GH and a predominance of rapid eye movement (REM) sleep. The nadir activity of the pituitary-adrenal system during early sleep reflects an active inhibition of this 'stress' system. One of the factors mediating this inhibition presumably is the sleep associated hypothalamic secretion of a release inhibiting factor of ACTH. In addition, limbic-hippocampal neuronal networks contribute to the inhibitory control over HPA activity during early sleep. Those structures appear to coordinate HPA inhibition and cortical activity (with prevalent SWS) during early sleep, thereby facilitating the formation of memories in sleep. As indicated by studies testing the effects of elevated plasma glucocorticoid levels, the inhibition of HPA activity during early sleep is an essential prerequisite for the memory function of sleep. Possibly, immunological memory formation likewise benefits from this inhibition. The suppression of pituitary-adrenal secretory activity during early sleep can be significantly weakened after profound acute stress as well as in states of chronic stress (including normal aging) which thereby disturb regular memory formation in sleep.

Journal Article↗

PubMedDate not supplied

Changes in emotional responses to aversive pictures across periods rich in slow-wave sleep versus rapid eye movement sleep.

OBJECTIVE: Since Freud's "Interpretation of Dreams," sleep has been related to emotional functions, where dreams were assumed to play a cathartic role. In psychophysiological research, this role was attributed mainly to rapid eye movement (REM) sleep. The present study compared processing pictures with negative emotional impact over intervals covering either early sleep dominated by slow-wave sleep (SWS) or late REM sleep-dominated sleep. METHOD: Emotional reactions were assessed by a nonverbal rating procedure along the two emotional dimensions valence (positive vs. negative) and arousal (low vs. high). Two groups of healthy men were tested across 3-hour periods of early and late nocturnal sleep (sleep group) or corresponding intervals filled with wakefulness (wake group). After the intervals, subjects rated new pictures together with old pictures already presented before the interval. Sleep was recorded polysomnographically. RESULTS: As expected, the amount of REM sleep was about three times greater during late than early nocturnal sleep, whereas a reversed distribution was observed for SWS (p<.001). Valence ratings indicated a shift toward enhanced negative ratings after late sleep (p<.05), contrasting with a trend toward more positive ratings after early sleep (p<.10). Arousal habituated slightly to repeated presentation of the same stimuli, but sleep generally enhanced subsequent arousal ratings (p<.05). Effects of sleep did not depend on whether pictures had low or high emotional impact. CONCLUSIONS: Indicating a priming-like enhancement of emotional reactivity after periods rich in REM sleep, results do not confirm a cathartic function of REM sleep or sleep in general.

Adolescent↗