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Biomedical subjects

T Larsen

Publications and source records attributed to T Larsen.

157 records · Page 9Linked to original sources
PubMedDate not supplied

Pancreatic secretion of zinc and carboxypeptidase A and B in growing pigs.

The secretion of zinc and the level of carboxypeptidase A and B activity in pancreatic juice were studied in three pigs fitted with a pancreatic pouch re-entrant cannula (PM pigs) and three different pigs with a catheter surgically implanted in their pancreatic duct (CM pigs). The zinc in the pancreatic juice appeared to be primarily associated with carboxypeptidase A and B. Both the concentration of zinc in pancreatic juice and the daily secretion of zinc in PM pigs were greater than in CM pigs. However, compared to the daily intake of zinc, its secretion in pancreatic juice was low. The specific activity levels of carboxypeptidase A and B in pancreatic juice collected from PM pigs were higher than in CM pigs. The total activity of carboxypeptidase A in pancreatic juice did not differ between collection methods. The total activity of carboxypeptidase B was higher in pancreatic juice collected from PM than from CM pigs. The differences in zinc and carboxypeptidase secretion between PM and CM pigs were probably due to physiological changes induced following the different surgical preparations of the animals.

Animals↗
PubMedDate not supplied

Changes in the cultivable flora in deep carious lesions following a stepwise excavation procedure.

This study examined the cultivable microflora before and after stepwise excavation procedures in deep carious lesions in 9 permanent teeth, categorized according to degrees of proximal surface destruction. The final excavation was performed 4-6 months after the initial treatment, which included peripheral dentine excavation and removal of the central cariogenic biomass and the superficial necrotic dentine. Dentine colour and consistency were assessed by means of standardized scales before the application of a Ca(OH)(2) compound and temporary sealing. Reassessments were performed before and after the final excavation. Microbiological samples of the central demineralized dentine were obtained with a sterile bur before and after the first excavation, as well as before and after the final excavation. After anaerobic cultivation on enriched non-selective tryptic soy agar, 30 colonies from a representative area were identified by standardized biochemical and physiological tests. Before temporary restoration, a yellowish and light brown demineralized soft dentine was typically observed, and gram-positive rods accounted for 70% and lactobacilli for 50% of the total colony-forming units. Lactobacillus casei subsp. rhamnosus and Actinomyces naeslundii dominated the lactobacilli and the other gram-positive rods, respectively. Gram-negative rods were the next most frequent isolates, followed by streptococci, each group accounting for about 20% of the colony-forming units in positive samples. Before the final excavation, which did not cause exposure of the pulp in any of the cases, the retained demineralized dentine had changed into a darker and harder tissue, and the total colony-forming units, as well as the frequency and proportions of lactobacilli were substantially reduced. Gram-negative rods also declined, and the flora was dominated by A. naeslundii and various streptococci. In conclusion, the cultivable flora detected following the treatment interval had declined substantially, and the distribution of bacterial species did not represent a typical cariogenic microbiota of deep lesions, confirming the clinical findings of arrested caries progression.

Actinomyces↗
PubMedDate not supplied

Multi-applicator hyperthermia system description using scattering parameters.

Hyperthermia systems using electromagnetic phased arrays have often been investigated from a SAR distribution point of view. One of the problems in these systems is that the achieved SAR distribution is different from the intended one because of changes in the generator signals due to mutual coupling between applications. The use of circuit theory and S-parameters in the description of an N-applicator phased array system is introduced in this paper, and a compact matrix equation giving excitation as a function of generator signals is derived. Measurement of the S-parameters is discussed using a phased array deep heating system (Danish Hyperthermia Foundation (DHF)) as an example. In a phantom experiment a significant improvement in the SAR distribution is demonstrated when the developed method is applied.

Electromagnetic Phenomena↗
PubMedDate not supplied

McBride's operation for hallux valgus can be used in patients older than 30 years.

Over a 10-year period, 46 feet with hallux valgus in 36 patients were treated with the McBride procedure. The median age was 35 years. At follow-up of 2 to 11 years after operation, a reduction in the hallux valgus angles, the intermetatarsal angles and the width of the forefeet was found. In patients older than 30 years there were significant reductions. In patients younger than 30 years, the reduction was not significant. The rate of problems with daily footwear was reduced from 36 of 46 feet to 13 of 38 feet. The authors noted few problems and a high rate of satisfied patients, despite the age. In 37 of 46 feet the overall result was found satisfactory by the patients. The authors find that McBride's operation can be used for hallux valgus, also in patients above 30 years, in spite of the generally accepted restriction to younger individuals.

Adolescent↗
PubMedDate not supplied

The effects of two different crystalloid cardioplegic solutions on cultured human endothelial cells.

The effects on cultured human endothelial cells of incubation with two standard crystalloid cardioplegic solutions (St. Thomas' and Bretschneider's) for one or five hours at 10 degrees C or 20 degrees C were studied. The cells were prelabelled with 51Cr and cell injury was measured by release of 51Cr, cell detachment, and by electron microscopy. The injury was also studied after a rewarming period of 35 minutes in cell culture medium at 37 degrees C. Endothelial cells incubated with cell culture medium, but otherwise treated in a similar way, served as controls. Both cardioplegic solutions caused significantly greater release of 51Cr than cell culture medium when incubated at 10 degrees C or 20 degrees C. The Bretschneider's solution induced slightly more release of 51Cr than did the St. Thomas' solution. The cells did not become detached during incubation. Electron microscopy of the cells after 5 hours with the cardioplegic solutions at 10 degrees C revealed contraction of the cells, mild intracellular oedema, swelling of mitochondria, and blebs or craters on the luminal surface of the cells. After rewarming in culture medium for 35 min the cells were not contracted and showed only minimal signs of injury, indicating a rapid and nearly complete reversibility of the changes. The present observations indicate that cultured endothelial cells get some protection, albeit not optimal, from the two crystalloid cardioplegic solutions tested. The presence of procaine-CL increased the injurious effect of the solutions.

Bicarbonates↗
PubMedDate not supplied

Cold induced endothelial cell detachment in human saphenous vein grafts.

The effect of profound (4 degrees C) and moderate cooling (20 degrees C) on the endothelium of human saphenous vein grafts for aortocoronary bypass was studied. When harvesting the vein, a piece (5-6 cm) was taken for the study and divided in two equal parts. The segments were incubated in cell culture medium for 45 minutes at 4 degrees C and 20 degrees C respectively. They were then perfused with cell culture medium at a flow rate of 100 ml/min, with a pressure of 85 mmHg and a temperature of 20 degrees C. After termination of perfusion the percentage of luminal surface without endothelial cells was determined by morphometry with scanning electron microscopy. The veins that were exposed to 4 degrees C had a significantly higher degree of endothelial cell detachment than those exposed to 20 degrees C (p less than 0.003). This study indicates that cooling to 4 degrees C may be harmful to the endothelial lining of veins which are prepared for grafting into the arterial system. Such cooling should therefore probably be avoided.

Cold Temperature↗