Biomedical subjects
Publications and source records attributed to E Nielsen.
During determination of total body water and net water turnover in the harbor porpoise, Phocoena phocoena, it was demonstrated that the porpoise exchanged water with an isosmotic environment by way of free diffusion and with hypo- or hyperosmotic environment by way of osmosis.
The enantiomers of the glutamic acid central nervous system receptor agonist alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) were prepared via kinetic resolution of the racemic N-acetylated 3-methoxy derivative by reusable, immobilized aminoacylase. L-AMPA was more effective (IC50 = 0.6 microM) than D-AMPA (IC50 = 4.8 microM) in displacing racemic [3H]AMPA from binding sites on rat brain synaptic membranes in agreement with their relative in vivo excitatory potencies.
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The kinetics of migration of radiolabeled 8-methoxypsoralen into human cataract lenses were investigated in 12 patients undergoing operation. Lenses were examined from 2.5 - 72 h after intake of 3H-labeled 8-methoxypsoralen by mouth. Demonstrable amounts of activity was only found in two of three lenses studied 24 h after intake. The aqueous humor contained less 8-methoxypsoralen than serum. The results of the study may add support to the opinion that a less rigorous sunglass regimen than that recommended by certain PUVA centers may be justified.
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The development of immunoglobulins IgG1, IgG2a, IgM and IgA was studied in germ-free BALB/c mice during the first 14 weeks of life. A transfer of maternal IgG1 and IgG2a was demonstrated during the first 2 weeks of this period. Endogenous synthesis of immunoglobulins was found only for IgM, the level of which was significantly higher at the end of the period than in a conventional group. After oral association of germ-free BALB/c mice with an intestinal hexaflora, the serum concentrations of IgG1, IgG2a and IgA increased. The levels of IgA, and of IgG1, were higher in the associated group than in the conventional group.
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The significance of sensitizing compounds in the denture base for the etiology of the burning mouth syndrome (BMS) has been studied in 53 denture-wearing persons, seven males and 46 females. Epicutaneous patch tests were performed with standard concentrations of benzoyl peroxide, dibutylphthalate, dimethyl-p-toluidine, formaldehyde, hydroquinone, methylmethacrylate, p-phenylendiamine and with cadmium sulfate, potassium dichromate, cobalt chloride and nickel sulfate. Furthermore, patch testing was performed with filings from the denture mixed with the patient's own saliva. In cases with an inflamed oral mucosa, the presence of hyphae of Candida albicans was assessed by a smear technique. Positive skin reactions were observed in 15 persons to dimethyl-p-toluidine, hydroquinone, formaldehyde, methylmethacrylate, p-phenylendiamine, potassium dichromate, cobalt chloride and nickel sulfate, including three cases with reactions to filings from their dentures, and one patient who after subsequent testing showed skin sensitivity to balsam of Peru. In 12 cases an etiological connection could be traced between the oral symptoms and the denture base, indicating that contact sensitivity to base materials or to allergens and microbial antigens on the denture plate plays a greater role in the pathogenesis of BMS in edentulous persons than previously suggested.
When measuring sweating rates, close correspondence was found with the clinical estimation of hyperhidrosis. Corrosion was seen to increase with increasing sweat rates, reaching its maximum after an assumed rise in the actual sodium chloride concentration on the skin surface due to evaporation of water. The findings confirm that hyperhidrosis is of primary importance in the constitution of a 'ruster', and are also in good agreement with experimental reports. The small variations in palmar skin pH had no influence on the degree of corrosion; nor had the character of the metal surface. Of the two types of metal studied. corrosion was much more severe on the type having the lowest concentration of copper, thus confirming that increasing copper concentrations have a positive effect in reducing corrosion rates. At 50--60% relative humidity (RH) corrosion increased as time elapsed, whereas at 40% RH no corrosion developed on a sweat-contaminated plate. When exposed to 75% RH, metal samples became severely corroded in the course of a few days. Protective methods for the avoidance of rust are mentioned, with special emphasis on frequent handwashing.
The weight and height development of 51 boys and 48 girls who had developed diabetes prior to the age of 15 years was followed for a minimum of 3 years, mean 8.3 years, up to the age of 18 for the girls and 20 for the boys. In addition, the insulin requirements were recorded. Weight and height proved to be within the normal range, and height at onset of diabetes was normal. After a long duration of diabetes, however, there occurred a reduction of height increment of obout 1/2cm/year. This reduction was greater in children who rarely attended as compared with those who frequently attended a sub-specialized clinic. The daily dose of insulin increased with age, the greatest increase coinciding with the growth spurt. During the first 4 years of diabetes the 24-hour dose/kg body weight increased, indicating a decreasing endogenous insulin production. Later it was constant at around 0.9 i.u./kg. Modern management of diabetic children leads to normal adult stature.
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The antimicrobial drug 1-methyl-2-nitro-5-vinylimidazole (MEV) preferentially blocked DNA synthesis, was mutagenic and induced coliphage lambda in Escherichia coli. The antibacterial effects of MEV are the consequences of repairable damage to DNA, as shown by hypersensitivity of recA and uvr strains to MEV and related drugs, stimulation by MEV of DNA turnover which was dependent on the product of the uvrA gene, and the presence of cross-links in DNA from MEV-treated bacteria.