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Biomedical subjects

K Rasmussen

Publications and source records attributed to K Rasmussen.

At least 307 records · Page 17Linked to original sources
PubMed1986

Single unit activity of locus coeruleus neurons in the freely moving cat. I. During naturalistic behaviors and in response to simple and complex stimuli.

The single unit activity of presumed noradrenergic (NE) neurons in the area of the locus coeruleus (LC) was recorded in freely moving cats. Consistent with previous reports, the activity of LC neurons was found to be state dependent: active waking greater than quiet waking greater than slow wave sleep greater than REM sleep (virtually silent). The activity of these neurons showed no relationship to movement per se. In response to simple sensory stimulation, LC units showed a short latency, short duration excitatory response. In response to a variety of non-noxious naturalistic stimuli, e.g. rats, food and a conspecific, LC unit activity did not increase above an active waking baseline. However, in response to noxious stimuli, e.g. pinches, visual threats, emesis, and forced treadmill running, LC unit activity increased above that during active waking and reached its highest levels. These data, in conjunction with those in the following report, are consistent with a general role for NE-LC neurons in the organism's adaptive response to environmental and physiological challenges.

Action Potentials↗
PubMed1986

Single unit activity of locus coeruleus neurons in the freely moving cat. II. Conditioning and pharmacologic studies.

A series of experiments were carried out in which the single unit activity of presumed noradrenergic (NE) neurons in the area of the locus coeruleus (LC) was examined in freely moving cats during two conditioning paradigms and in response to pharmacologic manipulations relevant to anxiety. LC unit activity was examined during conditioned emotional response (CER) and conditioned food reward (CFR) training. During CER training, LC units showed a large increase in activity in response to a stimulus paired with a noxious air puff, whereas no increase in unit activity was seen in response to a stimulus not paired with the air puff (both comparisons relative to their appropriate control conditions). By contrast, during CFR training, a stimulus paired with a rewarding food delivery did not elicit a significant increase in LC unit activity relative to its appropriate control condition. Therefore, NE units in the LC greatly increase their activity in response to a stimulus that predicts the occurrence of a noxious event, but not in response to a stimulus that predicts the occurrence of a rewarding event. Administration of the anxiolytic drug diazepam (0.25 and 2.0 mg/kg, i.p.) had no significant effect on the spontaneous activity of LC neurons, but significantly reduced the excitatory response of LC neurons to simple stimuli. Administration of the anxiogenic drug yohimbine (2.0 mg/kg, i.p.) significantly increased the spontaneous activity of LC neurons. These results support the hypothesis that LC neurons play a role in aversive but not appetitive conditioning, and are consistent with the hypothesis that these neurons may play a role in anxiety. These data are discussed within the broader context of LC neurons mediating the organism's adaptive response to environmental or physiological challenges.

Acoustic Stimulation↗
PubMed1986

Single unit response of noradrenergic, serotonergic and dopaminergic neurons in freely moving cats to simple sensory stimuli.

The response of noradrenergic (NE), serotonergic (5-HT), and dopaminergic (DA), neurons to repeated presentations (once/2 s for 64 trials) of phasic auditory (click) and visual (flash) stimuli was examined in freely moving cats. All 3 groups of neurons displayed similar response latencies and somewhat similar durations of excitation to both stimulus modalities. 5-HT neurons in the mesencephalic raphe nuclei showed no decrease in responsiveness across trials to either of the stimuli. DA neurons in the substantia nigra displayed no decrease in responsiveness across trials to the auditory stimulus, but did display an approximately 50% decrease in response to the visual stimulus. NE neurons in the locus coeruleus showed an approximately 50% decrease in responsiveness to both the auditory and visual stimuli. These data are consistent with previous studies showing that the response of many neurons in the brainstem reticular formation habituates to the repetitive presentation of sensory stimuli. They also show that the response of reticular formation neurons are heterogeneous and that they can be subdivided on the basis of their neurochemical identity. Finally, these data provide support for the involvement of NE neurons, and to a lesser extent DA neurons, in various forms of behavioral plasticity.

Animals↗
PubMed1986

Oesophageal spasm in patients with coronary artery spasm.

Oesophageal manometry was performed in 20 patients with chest pain, of whom 10 showed coronary artery spasm (group I) and 10 did not (group II). In the basal state oesophageal spasms were recorded in 6 patients from group I but in none from group II (p less than 0.05). In group I the duration of oesophageal contractions was 4.50 +/- 0.65 s compared with 2.86 +/- 0.36 s in group II (p less than 0.05). Prolonged hyperventilation was performed during manometry by 7 patients from each group. In group I this caused chest pain in all 7, with electrocardiographic changes in 6; at the same time oesophageal spasms were intensified in 5 patients and began anew in 1. In group II no electrocardiographic changes were seen with hyperventilation, and 1 patient showed oesophageal spasm. These observations suggest a relation between spasm of the coronary arteries and spasm of the oesophagus.

Adult↗
PubMed1986

Occupational exposure to chlorinated organic solvents and its effect on the renal excretion of N-acetyl-beta-D-glucosaminidase.

Organic chlorinated hydrocarbon solvents are known to be nephrotoxic. However, very little is known about renal integrity after occupational exposure to these solvents. Increased urinary N-acetyl-beta-D-glucosaminidase (NAG) excretion caused by necrosis of renal tubular cells can be used as a marker for nephropathy. In this study trichloroethylene (TRI), trichloroethane and freon 113 exposed persons from metal industries have been clinically investigated, and urine samples analysed for NAG activity and for trichloroacetic acid concentration. In order to analyse for possible subclinical kidney damage a group of diabetic patients with subclinical nephropathy served as positive controls. A significant higher NAG activity (p less than 0.001) was found in the group of exposed workers as compared to the control group. About 10% of the exposed workers had an enhanced NAG value, corresponding to the level of diabetic patients with subclinical nephropathy. Increased NAG activity was observed in previously TRI-exposed persons, which might indicate induction of an autoimmune renal necrosis.

Acetylglucosaminidase↗
PubMed1986

Haemodynamic effects of pharmacological doses of secretin in patients with impaired left ventricular function.

The haemodynamic effects of secretin 4 CU/kg.h was studied in seven patients with impaired left ventricular function. Cardiac output (P less than 0.01) and stroke volume (P less than 0.05) increased persistently during the infusion period, whereas the total systemic resistance fell (P less than 0.01). Heart rate increased slightly (P less than 0.01). The systemic arterial pressure was unchanged except for a small, transient reduction at the onset of the infusion (P less than 0.01). The pulmonary capillary wedge pressure, the pulmonary artery pressure and the pulmonary arteriolar resistance were unaltered. In patients with depressed cardiac function, pharmacological doses of secretin increased left ventricular performance by means of arteriolar dilation and a positive inotropic effect is also suggested.

Adult↗
PubMed1986

Left ventricular ejection fraction determined with the nuclear stethoscope, gamma camera and contrast ventriculography.

Left ventricular ejection fractions (EF) were measured with a nuclear stethoscope (NSt, beat-to-beat and ECG gated summation method) and contrast ventriculography (VG) immediately following one another (IFOA) (r X 0.96 and 0.95, respectively, n = 13). NSt and ECG gated gamma camera (MUGA) recordings IFOA were compared (r = 0.97 and 0.96, respectively, n = 23) as were non-IFOA recordings (r = 0.90 and 0.91, respectively, n = 13). Correlation between repeated NSt EF measurements gave: r = 0.91 (n = 22) for both methods. Paired NSt recordings in an invasive test situation (during invasive angiocardiography) and in a noninvasive situation (supine, 30 min of rest) gave for patients with EF less than 50 (mean +/- S.D.): EF invasive = 36 +/- 12, EF noninvasive = 41 +/- 13 (n = 4, p less than 0.05), and for patients with EF greater than or equal to 50: EF invasive = 59 +/- 7, EF noninvasive = 57 +/- 7 (n = 9, N.S.). The mean paired differences (EF noninvasive -EF invasive) in the low (less than 50) and high (greater than or equal to 50) EF range differed significantly: +5.3 versus -1.3, respectively (p less than 0.001). The recordings with the ECG-gated summation method gave similar results. The heart rate (beats min-1) in the noninvasive and invasive situation were (mean +/- S.D.): 68 +/- 11 and 78 +/- 16, respectively (p less than 0.01). We conclude that the patients were in a higher level of stress in the invasive situation. Accordingly ventricles with normal contractility (EF greater than or equal to 50) reacted with a slight increase in EF, and ventricles with compromised function (EF less than 50) reacted with a decrease in EF, compared to the values in the noninvasive situation. Incorporated in a correlation between MUGA and VG are, besides methodologically based differences, test-situation based systematical differences. Consequently the results of MUGA method should be given uncorrected. The results documents the accuracy and reliability of the NSt.

Adolescent↗
PubMed1986

Exercise stress testing in angina patients with positive response to hyperventilation testing: influence of the coronary artery tone.

We studied the exercise stress test and the coronary artery tone in two groups of angina patients with comparable coronary atherosclerosis. Group I (20 males and 5 females, mean age 53.5 years) with a positive, and group II (22 males and 3 females, mean age 52.5 years) with a negative response to the hyperventilation test (HVT). A positive exercise stress test (ST depression greater than or equal to 1 mm) was found in 24 patients in group I vs. 15 in group II (p less than 0.01), despite a lower maximal rate pressure product (198 +/- 11.2 vs. 236 +/- 10.1, p less than 0.05) and maximal work load (110 W +/- 7.1 vs. 136 +/- 7.4 W, p less than 0.02) in group I. A high coronary artery tone (dilatation (DIL%) of the coronary arteries after nitroglycerin greater than or equal to 10%) was found in 18 patients in group I and in 4 in group II (p less than 0.01). DIL% was 22.6 +/- 3.8 vs. 5.8 +/- 1.4 in groups I and II, respectively (p less than 0.005). DIL% was significantly related to persistence of ST depression after exercise (r = 0.36, p less than 0.05), and 21 of 22 patients with high tone had a positive exercise stress test vs. 18 of 28 with low tone (p less than 0.05). These findings suggest that the coronary artery tone influences the response to exercise in some patients with angina. Since the patients in group I were identified by HVT, our results underline the clinical relevance of this test.

Angina Pectoris↗
PubMed1986

Neuropsychological symptoms among metal workers exposed to halogenated hydrocarbons.

A cross-sectional study was designed as a questionnaire investigation with the aim of mapping the load of symptoms, especially signs of neuropsychological dysfunction in relation to degreasing with halogenated hydrocarbons. The primary study group, 240 metal workers, comprised all identifiable persons engaged in degreasing with halogenated hydrocarbons in the county of Aarhus, the control group were 350 randomly selected semi-skilled metal workers. The final number of participants were 462 metal workers, corresponding to a rate of participation of 78.3%. The main findings were highly significant associations between exposure to halogenated hydrocarbons and symptoms of psychological dysfunction both at bivariate and multivariate analyses after adjustment for 4 potential confounder variables, age, alcohol consumption, neurological events and exposure to other organic solvents. Furthermore a dose-response-like relation could be demonstrated.

Adolescent↗
PubMed1986

Estrogen regulation of the biological activity of the avian oviduct progesterone receptor and its ability to induce avidin.

During primary estrogen stimulation of chick oviduct development, estrogen withdrawal, or secondary estrogen treatment, changes in the oviduct progesterone receptor (PR) occur. The presence of estrogen appears to regulate not only PR concentration but also its biochemical activity, i.e. its capacity to bind to nuclear acceptor sites and alter RNA synthesis. This study reports that estrogen regulates the nuclear binding capacity of the PR even more rapidly than previously reported in fully developed oviducts of chicks that have been injected daily for 4 weeks with diethylstilbestrol (DES). Further, the nuclear binding capacity of the PR correlates with the ability of progesterone (P) to induce avidin protein concentrations in the oviducts in vivo. The PR concentration in the oviducts increases 2-fold within 8 h of the last injection and the decreases to a minimal value by 24 h. Injection of [3H]P into the chicks shows that the in vivo nuclear localization of the steroid increases almost 4-fold at 8 h, followed by a similar decrease to minimal values by 24 h. Cell-free nuclear binding assays, using PR isolated at various times after the last DES injection and oviduct nucleoprotein complexes, indicate that the capacity of the receptors to bind to nuclear acceptor sites is regulated by the estrogen. The enhanced nuclear binding capacity of the isolated PR increases to maximal values by 12-14 h after the last estrogen treatment and then begins to decrease to minimal values by 24 h. Similarly, the ability of P to induce in vivo avidin protein concentrations and to alter general RNA synthesis in the oviducts is reduced by 70% (of the estrogen non-withdrawn chick levels) by 24 h after the last estrogen injection. These changes over the 24-h period after the last DES treatment are not due to changes in the serum DES concentrations. The following 10-day period of estrogen withdrawal reveals a cyclic decaying pattern in the capacity of the PR for nuclear binding. The P induction of avidin and alteration of RNA polymerase II activity, using nuclear run-off experiments, also show a similar cyclic decaying pattern. By 6 days of estrogen withdrawal, the PR is incapable of any nuclear binding, and P cannot induce avidin protein concentrations in the oviducts. Serum DES concentrations over this 10-day period display only a gradual decay.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1986

Pregnancy following kidney transplantation.

Following kidney transplantation, 20 women gave birth to 24 infants after the 28th gestational week. All babies were singletons, alive, and free from malformations. The mean weight was 2,595 g (range 1,420-3,200 g) and the mean gestational age was 37.8 weeks (range 32-40 weeks). The cesarean section rate was 75%. On dividing the patients into low- and high-risk groups, the rate of pre-eclampsia, prematurity, and intra-uterine growth retardation was 2-3 times as high in the high-risk as in the low-risk group. No patients experienced graft rejection during the pregnancy but, within 3 months after delivery, two rejection episodes occurred. Later, a further 5 patients experienced graft rejection. All infants developed normally. We conclude that pregnancy following renal transplantation generally has a normal outcome and that the function of the transplanted kidney is unaffected by the pregnancy.

Adult↗
PubMed1986

Transdermal nitroglycerin (Transiderm-Nitro) in the treatment of unstable angina pectoris.

Eighteen patients, 13 male and five female, with unstable angina pectoris and who had greater than or equal to 3 anginal attacks/day despite treatment with beta- and/or Ca-blockers were treated for three days with transdermal nitroglycerin (Transiderm-Nitro 25 mg/24 hours) in a randomised, placebo-controlled trial. A significant reduction of anginal attacks (p = 0.03) was demonstrated only during the first day of treatment. The lack of significant effects during the following two days was ascribed partly to the possible development of nitrate-tolerance, partly to a declining number of anginal attacks in the placebo-group during the trial period, for which reason the difference between the actively treated and the placebo group became smaller and finally the consumption of nicomorphine was considerably greater in the placebo group.

Administration, Cutaneous↗
PubMed1986

Behavioral effects of cochlear prosthesis on deafened monkeys.

No deleterious effects of electrical stimulation on deafened young monkeys were noted using the behavioral techniques described. Due to the small size of this study and the variability of individual monkey behavior, it is impossible to draw definitive conclusions from this study. However, the results strongly suggest that deafened young monkeys with functioning cochlear implants showed apparent improvement in social behavior over deafened nonimplanted subjects. These changes may result from environmental and vocalization sound awareness and/or prevention of auditory deprivation provided by the prosthesis.

Animals↗