Search PubMed⌕ Search

Biomedical subjects

T Christensen

Publications and source records attributed to T Christensen.

At least 181 records · Page 10Linked to original sources
PubMed1986

Fatigue and anxiety in surgical patients.

In 15 patients fatigue was assessed by an arbitrary scale, anxiety by the State-Trait Anxiety Inventory and concentration by various concentration tests before and 10 and 30 days after uncomplicated elective, abdominal surgery. Preoperatively, fatigue correlated to state-anxiety (r = 0.68) and trait-anxiety (r = 0.66). From pre- to postoperatively, fatigue had increased on both day 10 and day 30. State-anxiety decreased, while trait-anxiety was unchanged. Increase in fatigue 30 days after surgery correlated to increased state-anxiety (r = 0.65), but not significantly to trait-anxiety (r = 0.38). No correlation was found between increase in fatigue 30 days after surgery and the preoperative degree of state- and trait-anxiety, (r = -0.09, r = -0.29); respectively. Neither pre- nor postoperative performance during concentration tests correlated to postoperative fatigue. It is concluded that preoperative anxiety may not be decisive for the development of postoperative fatigue. Postoperative fatigue may be considered a symptom of deterioration in cardiovascular function, neuro-muscular performance and nutritional status rather than psychological factors.

Adult↗
PubMed1985

Codon-defined ribosomal pausing in Escherichia coli detected by using the pyrE attenuator to probe the coupling between transcription and translation.

This communication describes an assay for the relative translation efficiency of individual codons which makes use of the pyrE attenuator to probe the coupling between transcription and translation at the end of an artificial leader peptide. By cloning of short synthetic DNA fragments the codons to be tested were placed in the middle of the leader peptide and the downstream transcription of a pyrE"lacZ gene was monitored by measuring beta-galactosidase activity. The substitution, one by one, of three AGG codons for arginine with three CGT codons for the same amino acid residue was found to cause a two fold increase per codon of transcription over the pyrE attenuator, such that an eight fold higher frequency of pyrE expression was seen when all three AGG codons were replaced by CGT codons. No such effect of codon composition was observed, when the cells were grown with a low UTP pool which causes a reduction of the mRNA chain growth rate.

Base Sequence↗
PubMed1985

Influence of pre- and intra- operative factors on the occurrence of postoperative fatigue.

Subjective feeling of fatigue was assessed before and 10, 20 and 30 days after uncomplicated abdominal surgery in 52 patients and after minor otological surgery in 15 patients. In major surgery fatigue increased from 3.0 +/- 0.2 (mean +/- s.e.m.) arbitrary units pre-operatively to 6.1 +/- 0.3, 5.3 +/- 0.3 and 4.1 +/- 0.3 on day 10, 20 and 30, respectively (P less than 0.001). In contrast, after minor surgery fatigue did not change from before surgery (2.1 +/- 0.3) to day 7 (2.9 +/- 0.5) (P greater than 0.05), day 20 (2.3 +/- 0.4) (P greater than 0.4), or day 30 after surgery (2.1 +/- 0.3) (P greater than 0.9). Differences in fatigue between groups were significant postoperatively (P less than 0.001), but not preoperatively (P greater than 0.05). Mean duration of surgery was similar in the two groups. In the abdominal group an increase in postoperative fatigue did not correlate with age, sex, pre-operative degree of fatigue, actual body weight, triceps skinfold thickness (TSF), arm muscle circumference (AMC), anthropometric index (body weight X TSF X AMC) or serum-transferrin, but did slightly with pre-operative body weight related to ideal body weight (r = -0.3, P less than 0.05). Thus, the magnitude of the trauma and not the duration of anaesthesia may be important for occurrence of postoperative fatigue. Furthermore, fatigue after elective abdominal surgery seems to be unpredictable from the pre-operative status of the patient.

Age Factors↗
PubMed1985

Photodynamic effects and hyperthermia in vitro.

Cells from the established human line NHIK 3025 were labelled with hematoporphyrin derivative in vitro. Subsequently, the cells were treated with light and hyperthermia. The cells could be irradiated either before, during or after the incubation at a hyperthermic temperature. It was shown that hyperthermia given shortly after the light exposure gave a synergistic killing effect. In spite of some loss of porphyrins from the cells, the light sensitivity increased 20 min after a light irradiation. At later times, the cells apparently repaired some of the photodynamic damage at 37 degrees C. At higher temperatures, the repair was inhibited.

Carcinoma in Situ↗
PubMed1985

Electrical activity and arm muscle force in postoperative fatigue.

Muscle force of elbow flexors and quantitative electromyographic analyses were assessed before and 10 and 20 days after uncomplicated elective abdominal surgery in 20 patients. The findings were compared with subjective fatigue. Fatigue increased significantly from a mean preoperative level of 3.4 +/- 0.4 arbitrary units to 7.0 +/- 0.5 and 6.1 +/- 0.5 on postoperative days 10 and 20. Muscle force decreased by about 10% postoperatively. The duration of sustained contraction (endurance) at a force adjusted to 30% of maximum fell from 426 +/- 64 sec preoperatively to 301 +/- 22 sec 20 days after surgery (all differences significant). Postoperative increase in fatigue correlated significantly to decrease in maximum force (r = 0.45) and to decrease in endurance (r = 0.5). The electromyographic findings at a force of 2 kg and at 30% of maximum suggested activation of fewer motor units during short contraction in the early postoperative period. During sustained contraction there was more pronounced increase in mean amplitude 20 days postoperatively than before surgery. This may suggest that the decreased muscle performance in the late postoperative period was secondary to muscle fatigue.

Abdomen↗
PubMed1985

Treatment of mouse carcinomas with intratumoral injections of hematoporphyrin derivative and red light.

Hairless mice with subcutaneously transplanted Lewis Lung carcinomas were used to study the effects of treatments with hematoporphyrin derivative (HPD) administered by intratumoral injection, followed by exposure to red light. A tumor cure rate of 70-90% was obtained following a single treatment. The therapeutic response increased with increasing HPD doses and light fluences. At a certain dose a plateau seemed to be reached, where further dose increase only gave a limited gain in treatment response. A narrow range seems to exist between beginning therapeutic response and frank necrotic destruction. The number of mice that died after treatment increased with increase in tumor size, and there was a correspondence between the time of death and the severity of the phototoxic reactions. The best therapeutic response was obtained when the irradiation was performed 1/2-1 h after injection, and with tumors less than 6-8 mm in diameter.

Animals↗
PubMed1984

Postoperative fatigue and changes in nutritional status.

Subjective feeling of fatigue was quantified before and 10, 20 and 30 days after elective uncomplicated abdominal surgery in 36 otherwise healthy patients, using a constructed fatigue scale model. One third of the patients had a remarkable increase in fatigue which continued throughout the first postoperative month. The fatigued patients showed a more pronounced postoperative loss in weight (P less than 0.001), triceps skinfold caliper (P less than 0.001) and arm muscle circumference (n.s.) and had lower levels in serum transferrin (P less than 0.02). No correlation was found between postoperative fatigue and postoperative changes in blood haemoglobin, lymphocyte count, plasma albumin, electrolytes and various minerals. Development of late postoperative fatigue was unpredictable from pre-operative nutritional status, serum transferrin, albumin, electrolytes, haemoglobin, lymphocyte count and various minerals, as well as from age, sex and duration of surgery. These results suggest future therapeutic measures against the postoperative fatigue syndrome.

Adolescent↗
PubMed1984

RNA secondary structure and translation inhibition: analysis of mutants in the rplJ leader.

We have carried out measurements of the stable binding of the ribosomal protein (r-protein) complex L10-L7/L12 to mutant forms of the mRNA leader of the rplJ operon of Escherichia coli. One of the point mutations, base 1548, which lies within the L10-L7/L12-protected region, almost completely abolishes in vitro formation of a stable complex of L10-L7/L12 with rplJ mRNA leader, and a second point mutation, base 1634, strongly reduces it. These observations constitute strong support for the proposition that L10-L7/L12 binds to the rplJ leader in bringing about translational feedback. To account for the action of these and other mutations, and to explain the mechanism of translation feedback inhibition, we suggest a secondary structure model involving alternate forms of the rplJ mRNA leader.

DNA-Directed RNA Polymerases↗
PubMed1984

Effects of haematoporphyrin derivative and light in combination with hyperthermia on cells in culture.

Interactions between the photodynamic effect of haematoporphyrin derivative and hyperthermia are reported. Cells labelled with haematoporphyrin derivative and irradiated with red light were sensitized by heat, particularly when the cells were heated after the exposure to light. It is shown that there is a synergistic interaction between the photodynamic effect and hyperthermia (42.5 and 45 degrees C). Hyperthermia-induced inhibition of the repair of photodynamic damage is suggested as a mechanism for the interaction. The possibility that these findings may be advantageous to cancer therapy is discussed.

Antineoplastic Agents↗
PubMed1984

Diameter and pulsatile oscillations of the femoral artery recorded by ultrasound.

A new non-invasive method for in vivo investigations of the inner diameter and pulsatile oscillations of large muscular arteries by means of an ultrasound time-motion technique is presented. Each histologic layer of the arterial wall is identified at in vitro examination of the external iliac artery. The method has been used for in vivo investigations of 16 long term diabetics and of 16 non-diabetics. A reduction of the lumen and decrement in pulse deflections were found in the diabetics when compared with those of the normal group.

Adult↗
PubMed1984

Tumor-localizing and photosensitizing properties of the main components of hematoporphyrin derivative.

Both 3H-labeled and unlabeled hematoporphyrin derivative (HPD) were analyzed by high-pressure liquid chromatography (HPLC) and gel permeation chromatography. Four main components were isolated by HPLC, and two were isolated by gel permeation chromatography. The tumor-localizing ability of each component was tested and compared to that of 67Ga and 3H2O by injection in mice bearing Lewis lung carcinoma. The photosensitizing abilities of the HPLC-separated components in vitro were also tested. Finally, porphyrin extracts of tumors from mice given HPD were analyzed by HPLC. The tumor-localizing ability of the components increased with decreasing polarity. While crude HPD localized in tumor tissue only to the same extent as did 3H2O, Component 7 was almost as effective as was 67Ga in localizing in the tumor. The cellular uptake of HPD components increased with decreasing polarity. In accordance with this, the low-polarity components were the most effective photosensitizers.

Animals↗