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Biomedical subjects

L Johansson

Publications and source records attributed to L Johansson.

At least 217 records · Page 12Linked to original sources
PubMed1984

Effective dose equivalent from radiopharmaceuticals.

The concept of "effective dose equivalent", which was introduced by the International Commission on Radiological Protection (ICRP) for occupationally exposed workers, has also created the possibility of expressing by means of a single figure, the radiation risk to patients undergoing different medical radiodiagnostic procedures. In this study, we present the effective dose equivalent for various nuclear-medicine investigations. The figures given are primarily based on a review of data contained in the literature on the mean absorbed dose to various organs. In many cases, however, our own calculations, using biokinetic data derived from the literature, have been used. It was found that for the different radiopharmaceuticals, the effective dose equivalent per activity unit administered extends over an interval of five orders of magnitude, from 0.00015 to 20 mSv/MBq. For the technetium-labelled compounds, the absorbed dose for 90% of the substances lies within the narrower interval between 0.0060 and 0.025 mSv/MBq. With the aid of the figures presented, each nuclear medicine department will be able to estimate the effective dose equivalent and, hence, the risk to patients undergoing different investigations.

Adult↗
PubMed1984

Fracture of the anterior tibial spine in children.

Considerable differences of opinion exist concerning the best treatment of anterior tibial spine fractures in children. In this retrospective study of 32 cases, residual symptoms and/or clinical instabilities were found in 16 instances. Open surgery is suggested for displaced fractures in patients 10 years and older.

Adolescent↗
PubMed1984

Intestinal intramural haemorrhage after abdominal missile trauma--clinical classification and prognosis.

Various types of abdominal trauma, such as penetrating missile wounds, blast and severe blunt force, can cause haemorrhage within the intestinal wall. Such bleeding often is multi-sited. In a previous study on anaesthetized pigs subjected to missile trauma, the microscopic appearance of the lesions was described. Risk of perforation, even in lesions of primarily innocent appearance, was also demonstrated, in accordance with reports in the literature. The present study aimed to find a method for predicting which of such haemorrhages may be left untreated and which must be excised. For this purpose, 85 anaesthetized pigs were subjected to low-velocity missile injury to the abdomen. All intramural haemorrhages of the intestine without primary perforation was thereafter classified at laparotomy according to a few easily observed macroscopic criteria. The anaesthesia was maintained and the classification was compared with findings at a second laparatomy at the end of the observation period (maximum 4 days), when histologic study also was performed. The macroscopic criteria showed good correspondence with histologically observed mucosal ulceration and muscle damage. In 64% of the lesions there was macroscopic progression during the observation time, with perforation in 5.4%. Lesions with mean diameter larger than 10 mm, visible serosal defect and palpable mural defect carried the highest perforation risk (16%). Lesions fulfilling none of these criteria did not perforate. The study confirmed the risk of secondary intestinal perforation in primarily non-perforating intramural haemorrhage following abdominal trauma. The results also suggest that some simple macroscopic criteria may be useful for predicting this risk.

Abdominal Injuries↗
PubMed1984

Fluorescein angiography in the evaluation of intestinal intramural haemorrhage after trauma.

Intramural hemorrhage of the intestines occur after different types of abdominal trauma. These haemorrhages may lead to secondary perforation and peritonitis. As the bleeding often is multifocal, radical resections would entail correspondingly many anastomoses, with increased risk of complications. A method for macroscopic recognition of perforation risk was described in a previous report. The macroscopic criteria used in that classification have now been compared with a vital staining technique, involving intravenous injection of fluorescein. The fluorescence patterns of 'non-viability' accorded well with histologically observed damage to the muscular layer of the gut and with transmural devitalization. There was also good correlation with the macroscopic criteria in the previous classification, but the fluorescein method was higher predictive of transmural devitalization. When the methods were combined, the detection of dangerous lesions was still improved. Fluorescein staining is clinically applicable, and thus can be a valuable complement for discerning heightened risk of perforation in intestinal intramural haemorrhages.

Abdominal Injuries↗
PubMed1984

Intestinal intramural haemorrhage after blunt abdominal trauma.

Intramural haemorrhage of the intestine following blunt trauma to the abdomen has been described in several clinical studies. Though such lesions may have an innocent appearance at primary laparotomy, they lead to delayed intestinal perforation in some cases. In previous experiments with similar lesions produced by penetrating abdominal missile, the histologic appearance and the clinical course were documented in pigs observed under long-term anaesthesia. In the present study anaesthetized pigs were submitted to blunt abdominal trauma in an impact machine, whereby the impact velocity could be regulated. The intra-abdominal pressure and the delivered impulse were recorded and the incidence and histologic appearance of intestinal injuries were observed at laparotomy immediately after the trauma. Intramural haemorrhage was found to occur when the impact velocity exceeded 5 m/s. At impact velocity 20 m/s, intestinal rupture occurred primarily. The observed intramural haemorrhages had the same histologic appearance as those seen after penetrating missile injury. The same clinical course, consequently, could be anticipated after blunt trauma.

Abdominal Injuries↗
PubMed1984

Intra-operative irrigation of the peritoneal cavity with ampicillin in experimental posttraumatic peritonitis.

Penetrating abdominal wounds with injury to the intestines were inflicted on 24 anaesthetized pigs. The injured gut was resected. During this operation the peritoneal cavity in 9 pigs was irrigated with 3 litres of antibiotic solution (ampicillin 2 g/l). In 15 pigs the irrigation was done with 3 litres of saline solution only. During the postoperative observation period the animals were in continuous anaesthesia. Absorption of ampicillin, reduction of the peritoneal bacterial flora and emergence of resistant strains were evaluated. Ampicillin was rapidly absorbed to the systemic circulation, with an average peak concentration of 42.4 +/- 1.7 mg/l. The average half-life of the drug in serum was 54 +/- 4 min. The average density of the total aerobic flora decreased during the operation from 10(4.74) CFU/ml peritoneal exudate fo 10(1.20) CFU/ml, but increased to 10(5.16) CFU/ml during the posttraumatic observation period. Total anaerobic counts changed to similar extent. The results were not significantly different from the values in the saline-irrigation group. Ampicillin irrigation led to a significant increase of resistant strains, from 25% before irrigation to 97% at the end of the observation period.

Abdominal Injuries↗
PubMed1983

Radiation sensitivity of human histiocytic lymphomas in vitro.

The radiation sensitivity of five human lymphoma cell lines has been investigated. All cell lines were originated from tumours clinically classified as histiocytic lymphomas. Using biochemical and immunologic techniques it was found that only one of them was a true histiocytic lymphoma. This cell line had an appreciable shoulder on the survival curve and capacity to repair sublethal damage. The survival curves of the other cell lines had no shoulders and the cells had nearly no capacity to repair sublethal damage. Taken together with previously published experimental and clinical observations the results indicate that tumours which by conventional diagnostic techniques are classified as histiocytic lymphomas are very heterogeneous in radiation sensitivity. It is possible that tumours of true histiocytic origin are more resistant to radiation than tumours of lymphocytic origin.

Cell Count↗
PubMed1983

Composition of surface layers in unfixed autologous fascia lata heart valve grafts. A transmission electron microscopical study.

Sixty-nine patients underwent aortic valve replacement with frame mounted non-fixated fascia lata grafts. Nine patients still have their fascia lata valve in place after a period of between 9 to 11 years. Fifty-two grafts were available for histo-pathologic examination. The mechanism of valve thickening was studied by transmission electron microscopy (TEM). The major factor contribution to the thickening seems to be a surface accumulation of complex proteins, fibrin and platelets. Within the valvular tissue itself, subcellular degenerative products in cell cytoplasm, the interstitium and in the sub-surface layer also contributed. The thickening never exceeded one fifth of the original thickness of the valve.

Aortic Valve↗
PubMed1983

Intra-operative saline irrigation of the peritoneal cavity in experimental post-traumatic peritonitis.

A trial of intra-operative saline irrigation of the peritoneal cavity for the prevention of peritonitis was conducted in an animal model. Following abdominal missile injury with intestinal perforation, 43 anaesthetized pigs were operated on an randomly assigned to three treatment groups. In two of the groups intraperitoneal irrigation with 3 litres of saline solution was performed during the operation, using a jet technique in one group. A control group of pigs received no irrigation. The effect of irrigation was evaluated with quantitative bacteriologic studies of peritoneal exudate and peritoneal biopsy specimens. Continuous anaesthesia and assisted ventilation were used and the post-trauma observation period was 3 days. The average bacterial density in the peritoneal exudate decreased by more than 99% in all treatment groups during the operation, but increased to more than the pre-irrigation level during the observation period. Irrigation did not result in significantly greater elimination of the bacterial population. The mortality was not lower in irrigated animals than in the controls. Intra-operative saline irrigation thus did not prevent peritonitis in this experimental model.

Animals↗
PubMed1982

Determination of tocainide in human plasma by gas chromatography with nitrogen-selective detection after Schiff base formation.

Tocainide is a primary amine with antiarrhythmic properties derived from lidocaine. For biopharmaceutical and pharmacokinetic purposes an assay was developed that made use of Schiff base formation with methyl isobutyl ketone and gas chromatography with nitrogen-selective detection. The derivatization procedure was performed at 85 C for 10 min, although a longer time at this temperature caused degradation of the product. Of several structural analogues the p-methyl one was the internal standard of choice. The amine was extracted from alkaline samples with dichloromethane and, after evaporation, reconstituted in methyl isobutyl ketone. From plasma the yields were lower than those from aqueous samples but the addition of hydroxylamine 30 min before the extraction process resulted in the same yields. Hydroxylamine probably acts as a competitor for carbonyl groups in the biological sample. In addition to the enhanced yields patients' samples extracted after hydroxylamine treatment were analysed with better precision. With nitrogen-selective detection 500 nmol/l in a 0.5-ml sample could be quantified, which is well below the therapeutic levels. The method compared favourably with a liquid chromatography assay.

Anti-Arrhythmia Agents↗
PubMed1982

Radiosensitivity of human B-lymphocytic lymphomas in vitro.

The radiosensitivity of four human B-lymphocytic lymphoma cell lines has been studied. For all lines the Do values were in the range 1.3 to 1.8 Gy. None of the survival curves had an appreciable shoulder. The extrapolation numbers varied in the range 1.0 to 1.2. Thus, the cell lines had a low capacity to accumulate sublethal damage. Furthermore, split dose experiments showed that no line had the capacity to repair sublethal damage. Taken together with earlier published experimental and clinical observations the results indicate that the use of an increased number of fractions in radiotherapy of B-lymphocytic lymphomas might be of great benefit to the patients. A schedule with an increased number of fractions will probably be as efficient in killing the tumour cells as previously used schedules but the tolerance of adjacent normal tissue will probably increase.

B-Lymphocytes↗
PubMed1982

The haemodynamic effects of dopamine and prenalterol in patients after cardiac valve surgery.

The haemodynamic effects of prenalterol and dopamine were compared in 10 patients about 4 h after cardiac valve replacement during a phase of temporarily depressed myocardial function. The rate of infusion was adjusted to give similar increases in stroke volume with the two drugs (dopamine + 17% and prenalterol + 18%). Both drugs produced marked inotropic and chronotropic effects with significant increases in heart rate, cardiac output, arterial blood pressure, and left and right ventricular stroke work. The arterial blood pressure and the left ventricular stroke work increased significantly more with dopamine than with prenalterol, however. The systemic vascular resistance decreased significantly with prenalterol, whereas it was unchanged with dopamine. The effects of prenalterol could be traced after 90 min, whereas the effects of dopamine vanished within 15 min.

Adrenergic beta-Agonists↗
PubMed1982

Intramural haemorrhage of the intestine as an indirect effect of missile trauma.

An experimental model for the study of intramural haemorrhages in the intestinal wall following indirect trauma by low-velocity missile is presented. Penetrating or non-penetrating abdominal gun-shot wounds were inflicted on pigs. The macro- and microscopical appearance and development of the haematoma-like lesions were studied. The commonest sites of early (ca. 0.5 h) microscopical lesions were the loose submucosal connective tissue and the mucosa. Mucosal ulcerations were seen in about half of the pigs after 1.5 h. They were probably caused by severe circulatory disturbance after bleeding in the submucosa and mucosa. Later perforating lesions also developed, but not until after ca. 24 h.

Animals↗