Search PubMed⌕ Search

Biomedical subjects

T Nielsen

Publications and source records attributed to T Nielsen.

At least 73 records · Page 4Linked to original sources
PubMed1992

Sleep architecture in agenesis of the corpus callosum: laboratory assessment of four cases.

Whether the corpus callosum is essential for normal human sleep cannot be decided from current knowledge. We thus studied sleep architecture in four subjects with agenesis of the corpus callosum (ACC) and four control subjects matched for age, gender, and hand preference. All-night EEG, EOG, and EMG activity were monitored in the laboratory for one adaptation night and one data acquisition night. Standard sleep variables were calculated for the second night. Agenesis subjects were found to have a greater percentage of stage 3 + 4 sleep and a lower percentage of stage 2 sleep than control subjects. Agenesis subjects also tended to have more REM sleep periods and a shorter REM cycle length than controls. The pattern of results is similar to that produced by partial callosotomy. It is also relevant to two hypotheses about the function of the corpus callosum in sleep. First, the corpus callosum may facilitate synchronization of activity between homologous regions in the two hemispheres but interfere with synchronization of neuronal populations within each hemisphere. Its absence may thus explain both an augmentation of slow-wave activity (and thus more slow-wave sleep) and a decrease in interhemispheric EEG coherence. Secondly, the corpus callosum may play a role in the regulation of the ultradian rhythm which underlies timing and duration of REM sleep.

Journal Article↗
PubMed1991

[Ambulatory orthopedic surgery].

A one year survey of the patients assessment of out-patient orthopaedic surgery in local anaesthesia is presented. The report is based upon questionnaires (including 15 items) of 529 operations performed on 495 patients. A large group of knee arthroscopies are included. We found that many orthopaedic operations, formerly treated as in-patient procedures could be carried out in the out-patient clinic with only a minimal complication rate. 77% of the patients experienced no problems other than pain in their home following the out-patient surgical procedure. Nearly 80% of the patients would choose out-patient surgery in case of a new identical operation. 30% of the patients found the administration of the local anaesthesia very painful and 41% experienced discomfort and pain following surgery. In addition, a brief analysis of the economical aspect is given. In conclusion, out-patient orthopaedic surgery is well accepted by the patients. The use of local anesthesia alone is not always sufficient and administration of an oral analgesic drug both before and after the surgical procedure is recommended.

Adolescent↗
PubMed1991

The effect of hypnotically induced emotional states on brain potentials evoked by painful argon laser stimulation.

The relationship between pain perception and emotional states is well known. However, the nature of this relationship and how different emotional states affect sensory and cognitive dimensions of pain remains uncertain. Results from experimental investigations are often contradictory, which may be due to methodological difficulties in inducing pain and monitoring physiological responses. In addition, most studies have focused on a single emotion, and data on the relative effects of different emotional states are lacking. In the present study we attempted to eliminate some of these methodological problems. Laser evoked potentials were used as a quantitative correlate to pain perception and were measured in 12 highly hypnotically susceptible subjects during seven conditions: (a) a prehypnotic baseline condition; (b) a neutral hypnotic control condition; (c-e) hypnotically recalled anger, fear, and depression in randomized order; (f) a hypnotically recalled happy condition, and (g) a posthypnotic awake control condition. The pain evoked potentials were significantly decreased in the angry condition and significantly increased in the depressed condition compared with baseline. No differences could be detected for either the happy or the fear-related condition compared with the baseline or neutral hypnotic condition. A significant positive correlation between the subjective intensity of depression and the increase in evoked potentials was found, but none for the other three emotions. The results support earlier findings that clinical depression is related to increased pain perception, and findings that the expression of anger can inhibit the experience of pain.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Monocyte chemotactic activity in sera after hypnotically induced emotional states.

In a number of studies it has been shown that psychological factors in general and specifically emotional factors can be correlated to changes in immunological function and defence mechanisms. Although the mediating pathways between the central nervous system and the immune system still remain unclear, it is known that some of the 'classical stress hormones' such as cortisol and catecholamines have modulatory effects on different immunological parameters. In this investigation we wished to study the effect of brief hypnotically induced emotional states on monocyte chemotaxis and endocrinological parameters. Eleven highly hypnotically susceptible volunteers were, while in a deep trance, given suggestions to re-experience earlier life experiences involving intense anger and depression in random order. Before concluding hypnosis subjects were given suggestions to re-experience a feeling of happiness and well-being. Monocyte chemotactic activity in sera and serum levels of cortisol, as well as venous plasma levels of the catecholamines epinephrine, norepinephrine, DOPA and DOPAC, were measured before hypnosis, after each emotional state and immediately after hypnosis. The results showed a significant differences (P less than 0.02) in chemotactic activity between the angry and the depressed emotional states, the depressed state exhibiting a decreased chemotactic index compared with the angry state. Chemotactic index after the happy relaxed emotional state also showed a significant (P less than 0.01) increase compared with both chemotactic index before hypnosis and chemotactic activity after the angry and depressed state. Though there were significant differences between emotions and between emotions and the before-hypnosis-condition, no clear-cut significant differences between the emotional states of anger and depression could be detected for serum cortisol levels and catecholamine plasma levels. Significant positive correlations (P less than 0.01) for differences in chemotactic activity and differences in plasma DOPA levels between emotional states was found. When investigated in vitro, DOPA did not in itself exhibit monocyte chemotactic properties. No other significant correlations between differences in chemotactic activity and other endocrinological parameters could be detected. Soluble interleukin-2 receptors in serum were also measured. No significant differences were found.

Anger↗
PubMed1990

Interhemispheric EEG coherence during sleep and wakefulness in left- and right-handed subjects.

REM sleep is associated with the production of complex imagery sequences. Yet research is divided as to whether different brain regions are more or less coordinated in their functioning at this time. Some research suggests that there may occur a functional disconnection of the left and right cerebral hemispheres during REM sleep which is similar to the disconnection syndrome seen after corpus callosotomy. Other research suggests that an increase in interhemispheric coordination occurs. On the assumption that hemispheric coordination is reflected in the EEG coherence measure, we explored differences in interhemispheric coherence recorded in six left- and six right-handed normal subjects during periods of wakefulness, stage REM, stage 2, and stage 3/4 sleep. Strong evidence was found that mean EEG coherence values are larger during sleep than during waking and that they are approximately equal for the different stages of sleep. Frontal electrode placements demonstrated a slightly different pattern of coherence than central, parietal, or occipital placements. Furthermore, coherence values were larger for left-handed subjects over the occipital region during wakefulness, stage 2, and stage REM sleep, but not during stage 3/4 sleep. Coherence was not different for male and female subjects. These findings oppose the interpretation that a functional disconnection of hemispheres occurs during REM sleep and favor the interpretation that sleep in general is a state of heightened cortical coordination. Moreover, greater interhemispheric coherence over occipital brain regions in left-handed subjects suggests possible differences in the cognitive processes of these subjects during waking and dreaming states.

Brain Mapping↗
PubMed1990

Interhemispheric EEG coherence before and after partial callosotomy.

Measures of interhemispheric EEG coherence during REM and NREM sleep reflect the functional connectivity of the right and left hemispheres mediated by the corpus callosum. Surface recordings of interhemispheric coherence in two patients reflected fairly accurately the degree of anatomical section produced by partial callosotomy. With further development, EEG coherence may prove useful as a noninvasive method for assessing interhemispheric integration under different physiological and experimental conditions.

Adult↗
PubMed1989

Demonstration of in vitro synthesis of human papilloma viral proteins from hand and foot warts.

HPV particles purified from [35S]-methionine labeled and unlabeled halves of single hand and foot warts have been fractionated into empty, light full, and heavy full particles by buoyant density gradient centrifugation, and their proteins analyzed by two-dimensional gel electrophoresis (IEF and NEPHGE) and visualized by either fluorography or silver staining. The L1 coat protein (54 Kd) was found in trace amounts in unmodified and slightly modified forms in the labeled empty and light full particles but could not be detected in the labeled heavy particles. L1 appeared to exist in the three unlabeled particle types in differentially modified forms. A putative L2 protein was also found to be modified (74-80 Kd) and was found preferentially in the unlabeled heavy full particles. The commercial cross-reactive BPV antibody recognized a labeled 58-Kd protein found predominantly in the empty and light full particles and a pair of proteins (41-42 Kd) found unlabeled in the heavy full particles. Besides L1, there were several other proteins (IEF 40 Kd; NEPHGE 42, 38, and 36 Kd) which were detected labeled in the empty particles and in increasing unlabeled amounts in the light full and heavy full particles. Four proteins (IEF 66, 13 and 11 Kd, and NEPHGE 9 Kd) were found exclusively in the full particles and may be involved in packing the viral genome. These observations suggest that a virus particle assembly pathway exists from the empty particles, via the light full, to the mature heavy full particles.

Bovine papillomavirus 1↗
PubMed1989

The outcome of Pneumocystis carinii pneumonia in Danish patients with AIDS.

A total of 100 consecutive patients with AIDS were evaluated for efficacy and safety of treatment and secondary prophylaxis directed against Pneumocystis carinii pneumonia (PCP). 89 episodes of PCP were recorded in 75 patients. 63 of the 75 patients (84%) with a first episode of PCP were discharged. Of 72 patients with a first episode of PCP who were initially treated with trimethoprim-sulfamethoxazole. 76% completed therapy successfully. Side effects were common, but generally mild and tolerated during continued treatment. 7/11 patients (64%) with a first episode of PCP who required mechanical ventilation were discharged. Long term prognosis for these patients was not worse than for patients who did not require mechanical ventilation. Relapse of PCP occurred in 3/50 patients (6%) during secondary prophylaxis, 160 mg trimethoprim and 800 mg sulfamethoxazole (TMP-SMZ) every 24 h, compared to 11/16 (69%) patients who were not receiving prophylaxis (p less than 0.00001). No patients discontinued prophylaxis because of side effects. It is concluded that for most patients with AIDS and PCP, treatment and secondary prophylaxis with TMP-SMZ is safe and effective.

Acquired Immunodeficiency Syndrome↗
PubMed1988

The excitatory amino acid antagonist kynurenic acid administered after hypoxic-ischemia in neonatal rats offers neuroprotection.

The neuroprotective effect of kynurenic acid, an unspecific antagonist of excitatory amino acid receptors, was evaluated in a model of hypoxic-ischemia in neonatal rats. One-week-old rats were subjected to ligation of the left carotid artery and exposure to 7.7% O2/92.3% N2 for 2 h. Kynurenic acid (300 mg/kg) was administered i.p. immediately after the period of hypoxic-ischemia in one group (n = 32) and compared with saline-treated (n = 27). After 2 weeks the rats were sacrificed and the brain damage evaluated by comparing the weight of the lesioned and unlesioned hemispheres. In rats receiving kynurenic acid the reduction in weight of the lesioned hemisphere was 25.4 +/- 3.3% as compared to 37.8 +/- 3.6% in saline-treated controls (P less than 0.001). The results suggest that excitatory amino acids are involved in the development of postischemic damage in the immature brain.

Animals↗
PubMed1985

Multinomial distributions in ploidy analysis.

Ploidy patterns can be summarized in the form of a vector of proportions representing the frequency of occurrence of DNA contents in specified intervals. Data represented in this way can be analyzed statistically using the multinomial distribution. Properties of the multinomial distribution and computational difficulties that arise in its application are considered. Special problems involved in formulating hypothesis tests and confidence regions for multivariate discrete distributions are discussed in the context of evaluating vectors of proportions representing DNA ploidy patterns. Construction of tailor-made critical regions for detecting specific types of deviations from normal ploidy patterns is proposed, and a detailed example is given. In this example, two critical regions are compared: a standard critical region, consisting of cases whose probability of occurrence is small, and a diagnostic critical region, consisting of cases considered to be clinically indicative of abnormality. Advantages of the diagnostic critical region are noted.

DNA↗
PubMed1984

Cellular distribution of thyroid myosin.

The subcellular localization of myosin in thyroid was investigated by both immunofluorescence and biochemical techniques. Dog thyroid cells stained with antisera to gizzard or thymus myosins showed that epithelial cells from thyroid contain nonmuscle myosin but not smooth muscle myosin. The antimyosin staining appeared at the periphery of the cell and in fibrils within the cell. The nature and subcellular localization of the myosin were further probed using biochemical techniques. Bovine thyroid plasma membranes were isolated by flotation on sucrose density gradients and subsequently extracted with 1% Triton X-100 to prepare an insoluble cytoskeletal fraction. After washing to remove residual Triton X-100, sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the cytoskeletal fraction demonstrated two major bands and several minor bands. The higher molecular weight band of the two major bands comigrated with the 200,000 mol wt heavy chain of myosin. Phosphorylation of the cytoskeletal fraction by thyroid myosin light chain kinase demonstrated a calcium- and calmodulin-dependent phosphorylation of the 20,000 mol wt light chain of myosin. Furthermore, the cytoskeletal fraction contained a myosin-type EDTA-K+ ATPase activity which was not influenced by ouabain and sodium azide. These results demonstrate the association of myosin with thyroid plasma membranes. Little myosin was solubilized by incubation of the thyroid plasma membranes with 0.6 M KCl; however, the addition of 10 mM ATP and 10 mM MgCl2 solubilized most of the myosin, indicating that it is associated with the thyroid plasma membranes through interaction with actin filaments. The presence of myosin in the thyroid plasma membranes may be important in endocytosis and exocytosis involved in thyroid hormone secretion.

Adenosine Triphosphatases↗
PubMed1983

The fate of airborne polycyclic organic matter.

Biological tests have shown that a significant part of the mutagenicity of organic extracts of collected airborne particulate matter is not due to polycyclic aromatic hydrocarbons (PAH). It is possible that part of these unknown compounds are transformation products of PAH. This survey focuses on the reaction of PAH in the atmosphere with other copollutants, such as nitrogen oxides, sulfur oxides, ozone and free radicals and their reaction products. Photochemically induced reactions of PAH are also included. The reactivity of particle-associated PAH is discussed in relation to the chemical composition and the physical properties of the carrier. Recommendations for future work are given.

Air Pollutants↗
PubMed1983

Laser-Doppler measurement of digital blood flow regulation in normals and in patients with Raynaud's phenomenon.

Finger blood flow was measured continuously by a laser-Doppler flowmeter in normal subjects and in patients suffering from primary or secondary Raynaud's phenomenon. In normals, skin areas with and without arteriovenous anastomoses could be differentiated. Blood flow in areas with shunt vessels decreased after a deep breath but not during venous stasis or the Valsalva maneuvre, while in other skin areas a decrease in blood flow was observed after all three maneuvres, suggesting a dual innervation of nutritional and shunt vessels. In patients with Raynaud's phenomenon (scleroderma) fingertip blood flow reacted in the same way as normal skin without shunt vessels. During direct and indirect cooling, finger blood flow in patients with secondary Raynaud's phenomenon reacted with the same relative reduction as normals but resting blood flow in the patients was significantly decreased and the rewarming period was greatly prolonged. In patients with primary Raynaud's phenomenon an even more prolonged decrease in blood flow was observed after direct or indirect cooling. Defective function of arteriovenous anastomoses is proposed as an explanation of the deviations from normal. A pathophysiological classification of Raynaud's phenomenon may be possible on the basis of the function tests described.

Adult↗