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Biomedical subjects

J Born

Publications and source records attributed to J Born.

At least 19 recordsLinked to original sources
PubMed1992

Event-related potential correlates of impaired selective attention in children at high risk for schizophrenia.

Auditory event-related potentials (ERPs) associated with selective attention were recorded in 21 children at high-risk for schizophrenia and in 21 matched controls. The subjects performed a selective listening task. For behavioral evaluation, target counts on the selective listening task and on cognitive performance were assessed. Group-specific differences of ERP components could be demonstrated, as reflected by significant amplitude reductions of the frontally located negative difference wave (Nd) and of the P3 component, following selectively attended stimuli, in the high-risk children. P3 latencies tended to be prolonged in the high-risk group. Reduced Nd was found in 14 and reduced P3 in 16 high-risk children among the 21 matched pairs. Significant correlations between the ERP reductions and psychometric deficit (counting accuracy) were observed. Mismatch negativity (MMN), an ERP component associated with automatic processing of physically deviant stimuli, did not differentiate significantly between groups, but was distinctly reduced in the high-risk group. The Nd and P3 reductions suggest deficits of selective attention in a considerable number of the subjects genetically at risk for schizophrenia. The present findings are discussed with respect to their relevance as indicators of a predisposition to schizophrenia.

Adolescent↗
PubMed1992

Norepinephrine amplifies effects of vasopressin on the isolated rat heart.

We compared effects of perfusion of norepinephrine (NE, 10(-9) mol l-1 and of unchanged Krebs-Henseleit solution on the cardiac response to bolus injection of arginine vasopressin (AVP, 2 ng). 14 isolated rat working heart preparations were used in a balanced cross-over design. Coronary flow, oxygen consumption and extraction, heart rate and total flow were continuously recorded. The concentration of NE was below that exerting per se systematic influences on cardiac activity. However, NE changed the cardiac response to AVP: (1) the AVP-induced reduction in coronary flow was greater during NE (mean: 41.7%) than vehicle perfusion (30.5%, P less than 0.005. (2) The AVP-induced decrease in oxygen consumption was stronger on top of the NE (41.5%) than vehicle perfusion (33.6%, P less than 0.005). (3) Following AVP, oxygen extraction during NE was increased compared to oxygen extraction during vehicle perfusion (3.61 +/- 0.03 vs. 3.46 +/- 0.02 microliters O2 ml-1 g-1, P less than 0.005). Results support the view of a potentiating role of catecholamines for direct cardiovascular effects of AVP.

Animals↗
PubMed1992

Effects of calcitonin on human auditory and visual evoked brain potentials.

Besides its Ca(++)-regulative effects, calcitonin is known to diminish sensitivity to painful stimuli. The present study aimed to clarify whether calcitonin has similar effects on stimulus processing in other modalities. Effects of calcitonin were assessed on brain potentials recorded from the human scalp which were evoked either by auditory clicks or visual checkerboard pattern-reversals. Twelve healthy men were tested in a double-blind intra-subject design receiving either 0.1 IU/kg salmon calcitonin (sCT) or 1.0 IU/kg sCT or saline solution during a 20 min IV infusion. sCT significantly increased latency of wave V of the brainstem auditory evoked potential (BAEP). Effects of BAEP wave V increased in magnitude with increasing dose of sCT and with decreasing intensity of the click stimulus. There was also a slight increase in latency of the N80 of the pattern-reversal visual evoked potential (PR-VEP). Additionally, subjects rated themselves as less activated following the high dose of sCT compared to placebo. The pattern of results is in accord with a slowing or inhibitory influence of calcitonin on auditory and visual sensory processing, thus paralleling findings concerning calcitonin effects on the perception of painful somatosensory stimuli.

Acoustic Stimulation↗
PubMed1992

Attention, cognition, and motor perseveration in adolescents at genetic risk for schizophrenia and control subjects.

Twenty-three offspring of schizophrenic parents (mean age = 12.1 years, SD = 3.2) and 61 adolescent control subjects (mean age = 12.3 years, SD = 3.3) were compared in their performance of the following psychometric tests: simple reaction times (RTs), warned RTs in a monomodal and cross-modal design, d2 concentration test, a motor perseveration test, and a cognitive performance measure (Wechsler Intelligence Scale). The results were validated in a second analysis in which a subgroup of the control subjects were matched to the high-risk subjects for the following characteristics: age, gender, education, and environmental background. Significant deficits were found in the high-risk group in tests that required sustained attention and information processing under high perceptual load (RT measures and d2 concentration test). Deficits were particularly prominent for the processing of visual stimuli; sensory incongruence might also have been a contributor to this deficit. The attentional dysfunction of high-risk subjects might explain their tendency to show less structured behavior and distractibility as reflected by their higher entropy scores in a motor perseveration test. Cognitive evaluation showed a significant deficit in the high-risk group, primarily as reflected in the verbal IQ score.

Adolescent↗
PubMed1992

Vasopressin regulates human sleep by reducing rapid-eye-movement sleep.

In two double-blind experiments, effects of intravenous infusion of arginine vasopressin (AVP) on sleep were evaluated in 2 groups of 10 men (20-35 yr). In experiment I, subjects were tested on two occasions, during which they received either placebo or 0.33 IU/h AVP. In experiment II, on three different occasions, subjects received either placebo or 0.66 or 0.99 IU/h AVP. Infusions were administered between 2200 and 0700 h. Nocturnal plasma AVP concentrations were close to the upper limit of the normal physiological range during 0.66 IU/h AVP (16.6 +/- 2.2 pg/ml) but markedly exceeded this range during 0.99 IU/h AVP (25.0 +/- 1.6 pg/ml). Results indicate primary effects of AVP on rapid-eye-movement (REM) sleep, with moderate reductions in REM sleep during 0.33 IU/h AVP (averaging -10.5%) and with substantial reductions in REM sleep (-24.0%) during 0.66 IU/h AVP. During 0.99 IU/h AVP the effect did not further increase (-24.4%). Less consistent effects of AVP were an increase in stage 2 sleep and in time awake. Effects of AVP were not mediated by changes in cortisol or blood pressure. Results suggest AVP to participate in REM sleep regulation under normal physiological conditions.

Adult↗
PubMed1992

Nocturnal adrenocorticotropin and cortisol secretion depends on sleep duration and decreases in association with spontaneous awakening in the morning.

It is still discussed controversially to what extent the nocturnal activity of the hypothalamus-pituitary-adrenocortical system depends on sleep and awakening in the morning. Therefore, we investigated the association of plasma ACTH and cortisol levels with undisturbed nocturnal sleep and spontaneous awakening in 14 healthy male subjects (between 2300 h and 1100 h). Between sleep onset and 476.9 min after sleep onset mean plasma cortisol level was significantly (P < 0.01) higher (210 +/- 15 vs. 155 +/- 9 nmol/L) in the group with a shorter (476.9 +/- 15.0 min; n = 7; mean +/- SEM) than in the group with a longer total sleep time (596.9 +/- 14.4 min; n = 7). Spontaneous awakening in the morning was not linked to the presence of any specific sleep stage or to rising plasma ACTH and cortisol levels. However, spontaneous awakening was followed by a brief rise in plasma ACTH and cortisol in both groups. Thereafter, during wakefulness plasma ACTH and cortisol abruptly declined in all subjects irrespective of the time of awakening. The slope of the plasma ACTH and cortisol curves differed significantly (ACTH: P < 0.001; cortisol: P < 0.002, for all subjects) comparing the time after awakening (until 1100 h) with a time interval of identical length before awakening. We conclude that the duration of sleep and nocturnal ACTH and cortisol secretion are interrelated. Furthermore, the data suggest that the endogenous early morning activation of the hypothalamus-pituitary-adrenocortical system is terminated by mechanisms closely associated with awakening.

Adrenocorticotropic Hormone↗
PubMed1992

[The effect of "stress hormones" on emotional sensitivity].

Stress is associated with an increased secretion of hormones from the hypothalamus-pituitary-adrenal-axis (HPA-axis). Once released into the blood stream they induce a number of adaptive changes that may also have pertinence to brain functions, resulting, for example in alterations of mood. To provide evidence for a mediation of mood changes by stress related hormone secretion, the influences of a short-term administration of hormones of the HPA-axis on mood and activation were assessed in a total of 182 healthy men (aged between 18 and 34 years in 7 experiments). Effects of intravenously administered hormones on self-perceived mood and activation were assessed by a standardized adjective checklist (Eigenschaftswörterliste) in placebo-controlled, double-blind experiments during rest. Results indicated no effects following corticotropin releasing-hormone or cholecystokinin, but specific effects resulted after vasopressin, oxytocin, ACTH-related hormones, and cortisol. Vasopressin and oxytocin increased activation and attenuated arousal and anger, ACTH-related hormones increased sensitivity and diminished extraversion, while cortisol increased activation and concentration. It is concluded that hormones of the HPA-axis specifically affect mood and activation. The pattern of hormonal changes in mood may have adaptive functions by preparing for behavioral and cognitive coping with stress.

Adult↗
PubMed1991

Endogenous event-related brain potentials and psychometric performance in children at risk for schizophrenia.

Two independent groups of high-risk children for schizophrenia and their matched control children were submitted to the following experiments: an auditory oddball paradigm registrating late event-related potentials (ERPs) and a psychometric test battery including the assessment of Wechsler Intelligence Scales, reaction times (after regular and irregular preparatory intervals), and the d2-attention test. The study was intended to clarify whether long-latency ERPs and the selected psychometric tests would contribute to reliably differentiating between these groups. The results showed significantly prolonged latencies of the P3 component of the ERPs to rare, task-relevant target stimuli in both high-risk groups compared with the controls. Similarly, the N2 latencies were delayed in both groups. By contrast, ERP patterns to frequent, nontask-relevant stimuli were very similar, with no significant differences between high-risks and normals; nor did any ERP amplitudes show significant differences. The data are interpreted as a reflection of a subtle deficit in maintaining attention and a subsequent impairment of stimulus discrimination in high-risk children. This is consistent with the psychometric findings of higher error scores in target counts and d2-test, and significantly prolonged reaction times after regular preparatory intervals (PIs) in the high-risks. The findings may hint at a vulnerability for schizophrenia in high-risk children. Given the high prevalence of the attentional dysfunctions in both high-risk groups, however, it is hypothesized their presence does not necessarily imply an unequivocal manifestation of schizophrenia.

Adolescent↗
PubMed1991

Sleep disruption alters nocturnal ACTH and cortisol secretory patterns.

Recent studies have provided evidence that nocturnal cortisol secretion is coupled to ultradian rhythms of sleep. The present study was designed to specify how exogenous and sleep-related endogenous factors influence nocturnal adrenocorticotropin (ACTH) and cortisol secretion. We compared the influences of (1) temporary sleep deprivation, (2) arousals continuously induced during sleep and, (3) undisturbed sleep (baseline) on pituitary-adrenocortical activity in 10 healthy men. Sleep deprivation (DS) and continuous arousals during sleep (AS) were introduced at the beginning of the second rapid eye movement (REM) sleep period which is an epoch close to the first significant nocturnal rise in plasma cortisol. Compared with the baseline nights, plasma cortisol significantly increased immediately after continuous arousals were started or the subject was awakened and remained awake. Despite this exogenously provoked first cortisol peak, average cortisol release during DS and AS was no higher than during undisturbed sleep. The arousal-induced cortisol burst was followed by a temporary inhibition of cortisol secretion, suggesting that once the subject is aroused (i.e., in stage 1 sleep or awake), the hypothalamus-pituitary-adrenal (HPA) system becomes highly sensitive to negative feedback inhibition. Spontaneously occurring endogenous cortisol peaks of comparable size during undisturbed sleep did not exhibit such a temporary inhibition of cortisol secretion. We hypothesize that sleep attenuates negative feedback inhibition within the HPA system, whereas wakefulness (or stage 1 sleep) reflects increased feedback sensitivity of this system.

Adrenocorticotropic Hormone↗
PubMed1991

The vegetalizing factor from chicken embryos: its EDF (activin A)-like activity.

The erythroid differentiation capacity of the HPLC-purified mesoderm- and endoderm-inducing vegetalizing factor from chicken embryos and of recombinant erythroid differentiation factor (EDF = activin A), an evolutionary highly conserved member of the TGF-beta protein superfamily have been compared. Both factors stimulate the synthesis of hemoglobin in erythroleukemia cells in the same concentration range. The EDF-activity of the mesoderm-inducing HPLC-fractions is inhibited by follistatin, an EDF-binding protein. The factor induces in ectoderm of Triturus taeniatus all kinds of mesodermal organs. The wide spectrum of organs is very likely to be induced by secondary interactions. At higher concentration (15 ng/ml), notochord- and endoderm-like tissues are induced in a high percentage.

Activins↗
PubMed1991

Brain evoked responses, a bioassay for central actions of adrenocorticotropin (ACTH 1-39) and corticotropin releasing hormone (CRH) in humans.

Blood borne hormones of the hypothalamus-pituitary-adrenal (HPA) axis form an afferent humoral system modulating a great variety of brain functions. In humans, bioassays consistently reflecting central nervous system actions have not been developed, so far. The present experiments are part of a series of studies which have been conducted to demonstrate the afferent influences of ACTH and CRH on brain activity by recording of auditory event-related brain potentials (ERPs) in healthy human subjects. In a double-blind within-subject comparison in 12 healthy male students, influences of 4 U ACTH and 100 micrograms CRH (infused within 2 h; the infusion starting 1 h prior to ERP recordings) were compared with the effects of a placebo infusion. Influences of the hormones were tested for the early, brain stem generated ERP components (BAEPs) and for the late components of the ERP associated with cortical stimulus processing. ACTH and CRH showed no consistent effect on BAEPs. ACTH, but not CRH, significantly reduced amplitudes of late ERP components, in particular, the Nd and P3 components which are considered signs of selective attention. These results are consistent with findings from previous studies demonstrating impaired ERP signs of selective attention in humans after administration of the 4-10 fragment of ACTH which lacks the peripheral adrenocorticotropic activity. Together with these foregoing studies, results from the present experiments further establish ERP methodology as a sensitive bioassay for CNS actions of hormones in humans.

Adrenocorticotropic Hormone↗
PubMed1991

Gluco- and antimineralocorticoid effects on human sleep: a role of central corticosteroid receptors.

Cortisol modulates brain functions in humans. This principal endogenous glucocorticoid in humans decreases rapid-eye-movement (REM) sleep and increases slow-wave sleep (SWS). Because cortisol exerts its effect on brain functions via mineralocorticoid receptors (MR) and glucocorticoid receptors (GR), we were interested in which type of corticosteroid receptor mediates these steroid effects on sleep. Healthy men were tested in two double-blind experiments. In experiment I (n = 8), the subject's sleep was tested during four nights: 1) after pretreatment with dexamethasone (Dex, 4 mg/day) for 4 or 6 days and after additional infusion of placebo or cortisol (10 mg/h) during the experimental night, 2) after pretreatment with placebo for 4 or 6 days and after infusion of placebo or cortisol (10 mg/h) during the experimental night. In experiment II, subjects (n = 10) slept after intravenous administration of potassium canrenoate (200 mg, at 0800 and 1700 h before experimental nights) or placebo. Cortisol infusion moderately increased the percentage of SWS (P less than 0.05) and markedly decreased REM sleep (P less than 0.01); influence of cortisol on SWS did not depend on pretreatment with Dex. Dex reduced both SWS and REM sleep (P less than 0.05). Canrenoate markedly diminished SWS (P less than 0.01) but left REM sleep unaffected. The results suggest that corticosteroid-induced changes in SWS are mediated via MR-like central receptors in humans, whereas changes in REM sleep involve GR.

Adult↗
PubMed1991

Adrenergic influences on cardiac function during ventricular fibrillation in isolated rat hearts.

Effects of norepinephrine (NE, 10(-6) M), epinephrine (E, 10(-6) M), and vehicle on coronary blood flow (CF), oxygen consumption, and lactate release were compared in 32 isolated rat hearts during 5 min of ventricular fibrillation (VF). After VF, tissue concentrations of ATP, AMP, creatinine phosphate (CP), and lactate were measured. Perfusion of treatments started 30 s after onset of VF and was maintained throughout VF. CF during VF was greater (P less than 0.005) during perfusion of E (mean +/- SE, 5.73 +/- 0.15 ml/min) than NE (5.06 +/- 0.32 ml/min) or vehicle (5.11 +/- 0.18 ml/min). Oxygen consumption during VF was higher during perfusion of E (29.5 +/- 0.9 microliters.min(-1).g wet heart wt(-1)) than vehicle (27.3 +/- 0.7 microliters.min(-1).g(-1); P less than 0.05); average oxygen consumption during NE (27.6 +/- 1.4 microliters.min(-1).g(-1)) and vehicle were comparable. After NE, but not E, tissue AMP concentrations were significantly increased, and CP concentrations were reduced compared with vehicle (P less than 0.05). Enhanced consumption of high-energy phosphates during NE suggests that there is also an enhanced demand for oxygen. However, unlike during E, during NE this demand is not met by an augmented CF. Thus, compared with E, NE treatment during VF may increase the risk of hypoxic damage.

Adenosine Monophosphate↗
PubMed1991

Evidence for entrainment of nocturnal cortisol secretion to sleep processes in human beings.

The pulsatile patterns of cortisol release have been referred to as 'episodic' rather than 'rhythmic'. We studied plasma cortisol patterns in 31 healthy subjects during night sleep and observed a uniform ultradian rhythm. Using spectral analysis a predominant mean periodicity of 151.2 +/- 8.3 min (mean +/- SEM) was calculated for plasma cortisol oscillations, and of 118.3 +/- 4.3 min for REM sleep occurrence. The rhythmic pattern of plasma cortisol was obscured when data were averaged across subjects, due to the individual onset latencies of the initial cortisol rise. Therefore, the data were analyzed time-locked to a number of somnopolygraphic sleep events: by selecting the end of the second sleep cycle as point of reference, the ultradian rhythm was preserved. These results indicate that both sleep processes and nocturnal plasma cortisol concentrations are subject to ultradian rhythms. Both rhythms are coupled, but have different periodicities.

Adult↗
PubMed1991

Sleep-associated augmentation and synchronization of luteinizing hormone pulses in adult men.

We reinvestigated the temporal relationship between sleep and LH secretion in healthy adult males by comparing LH secretion patterns during sleep with those during the 6 h of wakefulness preceding the sleep epoch. Sleep stages were determined by somnopolygraphy. In these subjects LH secretion was augmented during sleep as indicated by increased mean LH concentrations and increased pulse amplitudes; pulse frequency was not different. In addition, LH secretion appeared to be synchronized to the NonREM-REM sleep cycles: initiation of LH pulses occurred preferentially in the mid-portion of a NonREM-REM cycle during Non-REM sleep. Thus, REM sleep was almost uniformly associated with decreasing LH concentration. These findings demonstrate that patterns of LH secretion characteristic for early puberty are principally present also in adult males.

Adult↗
PubMed1991

Different regulation of adrenocorticotropin and cortisol secretion in young, mentally healthy elderly and patients with senile dementia of Alzheimer's type.

Previous studies suggest that an alteration of the neuroendocrine system may particularly occur in senile dementia of Alzheimer's type (SDAT). In the present study the reactivity of the hypophyseal-adrenocortical axis (HPA) in the elderly was assessed by hormonal stimulation of the hypophysis. Twelve young men (aged 21-24 yr), 15 mentally healthy elderly (aged 65-90 yr), and 12 patients with SDAT (aged 60-84 yr) received an iv bolus injection containing 50 micrograms CRH and 0.5 IU lysine vasopressin after a baseline period of 2 h. ACTH, cortisol, and dehydroepiandrosterone secretion was monitored over a period of 2 h before and after the injection. The baseline ACTH concentrations were increased in both groups of elderly, the baseline cortisol levels were not different in either group. The peak ACTH and cortisol levels were significantly elevated in the mentally healthy elderly, whereas senile demented patients showed a rise comparable with that in the young subjects. Moreover, in the demented patients the post-stimulus decline in plasma ACTH levels seemed to be delayed. Dehydroepiandrosterone was significantly lowered in subjects of all ages. Our results demonstrate an enhanced reactivity of the HPA in mentally healthy elderly. This is possibly due to a diminished sensitivity of the feedback regulation to glucocorticoids. However, SDAT patients had, compared to healthy elderly subjects, an attenuated response to CRH/lysine vasopressin and a prolonged ACTH secretion, indicating alterations of the HPA in this disease.

Adrenocorticotropic Hormone↗