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Biomedical subjects

M Lund

Publications and source records attributed to M Lund.

At least 19 recordsLinked to original sources
PubMed1992

In vitro effects of drugs on production of mucins in rabbit tracheal epithelial cells expressing mucin gene: a model system for studying upper airway respiratory diseases.

Rabbit tracheal epithelial cells, cultured on collagen-coated dishes in serum-free and hormone-supplemented medium, were found to incorporate [3H]glucosamine into high-molecular-weight components that were secreted in the medium. The chemical analysis of the secreted products resulted in a profile that resembled that of mucous glycoproteins (mucins). When examined by dot blot analysis, the total RNA isolated from these cells hybridized to an antisense 30-mer oligonucleotide corresponding to a rat intestine mucin peptide sequence, indicating that mucin gene was expressed in these cell lines. Lung and liver tissues of rabbit did not express this gene. Transmission electron microscopy exhibited secretory granules in these cells. The incorporation of [3H]glucosamine into mucins was inhibited by three aryl-N-acetyl-galactosaminides and a chemical carcinogen, N-nitroso-N-ethyl urea, whereas 5-azacytidine enhanced the proliferation of cells as well as the radiolabeling of mucins. Parasympathetic agent (pilocarpine), cholinergic antagonist (atropine), and beta-adrenergic agonist (isoproterenol) alone have little effect on the secretion of mucins. The cholinergic agonist, methacholine, was found to increase the production of mucins and addition of atropine to the medium before methacholine blocked this stimulation. Histamine was found to stimulate mucin production in these cells.

Amino Acid Sequence↗
PubMed1992

Dietary intake, exercise, obesity and noncommunicable disease in rural and urban populations of three Pacific Island countries.

Dietary intake surveys of rural and urban communities in three Pacific Island countries were conducted using an adjusted 24-hour dietary recall method. Dietary survey samples were drawn from noncommunicable disease surveys of Melanesians and Indians in Fiji, Micronesians in Kiribati and Melanesians in Vanuatu. Comparisons of total energy and macronutrient intakes and of obesity, hypertension, diabetes mellitus, serum cholesterol and physical activity levels revealed similar rural/urban trends. Urban subjects were more obese than rural ones, had higher prevalence rates of diabetes and hypertension, and generally had higher cholesterol levels. Rural subjects were leaner, suffered less from diabetes and hypertension, and had greater total energy intakes than urban dwellers. Rural people ate a greater proportion of carbohydrates, while urban subjects ate proportionally more protein and fat, apart from the outer Kiribati atolls with high coconut intakes. Rural subjects in all three studies had higher levels of physical activity. These studies provide persuasive evidence that exercise as well as diet has a significant effect on rural/urban differentials in obesity and noncommunicable disease, and that energy intake reflects energy expenditure.

Diet↗
PubMed1990

Peptide alpha-helicity in aqueous trifluoroethanol: correlations with predicted alpha-helicity and the secondary structure of the corresponding regions of bovine growth hormone.

The relationship between trifluoroethanol (TFE) enhancement of peptide alpha-helicity and protein secondary structure has been studied for a series of 11 peptides which span the complete primary sequence of bovine growth hormone (bGH). Ten of these peptides become increasingly alpha-helical as the solution concentration of TFE is increased. The amount of alpha-helicity developed by these peptides plateaus above 10 mol % TFE and ranges from 0 to 71%. The increased alpha-helicity, as determined by CD, closely correlates with the amount of alpha-helix predicted for eight of the eleven peptides analyzed (r = 0.9). Therefore, for this group of peptides, it appears that this technique can be used as a measure of alpha-helical propensity. Inclusion of the remaining three peptides in this analysis significantly lowers the correlation (r = 0.6). The reduced correspondence between TFE-enhanced and predicted alpha-helicity in this latter subset of peptides may be due to their relatively high hydrophobicity. In addition, the relevance of TFE-enhanced peptide alpha-helicity and the secondary structure of the corresponding protein regions was explored. Although the three peptides which form the largest amount of alpha-helicity in the presence of 10 mol % TFE correspond to alpha-helical regions of the protein, the overall correlation is significantly lower than is observed for the TFE-enhanced and predicted alpha-helicity. These findings suggest that the propensity of specific amino acid sequences for alpha-helix formation influences the amount of alpha-helicity which forms in corresponding protein sequences, but that other factors can modify this structure.

Amino Acid Sequence↗
PubMed1990

Chitinase, beta-1,3-glucanase, osmotin, and extensin are expressed in tobacco explants during flower formation.

Sequence analysis of five gene families that were isolated from tobacco thin cell layer explants initiating floral development [Meeks-Wagner et al. (1989). Plant Cell 1, 25-35] showed that two encode the pathogenesis-related proteins basic chitinase and basic beta-1,3-glucanase, while a third encodes the cell wall protein extensin, which also accumulates during pathogen attack. Another sequence family encodes the water stress-induced protein osmotin [Singh et al. (1989). Plant Physiol. 90, 1096-1101]. We found that osmotin was also induced by viral infection and wounding and, hence, could be considered a pathogenesis-related protein. These genes, which were highly expressed in explants during de novo flower formation but not in explants forming vegetative shoots [Meeks-Wagner et al. (1989). Plant Cell 1, 25-35], were also regulated developmentally in day-neutral and photoresponsive tobacco plants with high expression levels in the roots and moderate- to low-level expression in other plant organs including flowers. An unidentified gene family, FB7-4, had its highest level of expression in the basal internodes. Our findings indicate that these genes, some of which are conventionally considered to encode pathogen-related proteins, also have a complex association with normal developmental processes, including the floral response, in healthy plants.

Amino Acid Sequence↗
PubMed1988

Clinical application of epiderm growth factor in patients with most severe eye burns.

20 eyes of 11 patients suffering from most severe eye burns of grade 4 or worse were treated in addition to various other drugs with epiderm growth factor (EGF) or placebo in a double-blind test. Among 10 eyes treated with EGF, 6 achieved complete regeneration of the corneal epithelium, and 1 additional case, of the conjunctival epithelium. Among the eyes receiving placebo, only 3 out of 10 healed; all of them were also treated with fibronectin. Although in these very difficult cases EGF could not be investigated as a single therapy, and various other undefined factors may have been effective, in the extended course of the disease the period of EGF treatment was marked by a significant better regeneration of the epithelium.

Burns, Chemical↗
PubMed1987

Helical formation in isolated fragments of bovine growth hormone.

The peptide 109-133 was isolated from bovine growth hormone (bGH) and studied for helix formation in aqueous solutions. This fragment was shown to contain helical structure by far-ultraviolet circular dichroism in aqueous solutions. The amount of helix was dependent on pH and peptide concentration. The peptide has maximum helicity between pH 4 and 5 and at high peptide concentration. Under these conditions for maximal helix population, this fragment is approximately 100% helical. Secondary structure predictions suggest that residues 110-127 have a strong propensity to form an amphipathic helix. We have also studied a related peptide, 96-133, and show by gel filtration that it undergoes an increase in molecular weight that directly correlates with a coil to helix transition. A comparison of the helical content of 96-133 to 109-133 and circular dichroism studies of peptide 96-112 suggest that the helix of 96-133 is limited to the 109-133 region. Current models for alpha-helix formation predict that peptides the size of 109-133 should not contain measurable helicity in aqueous solutions. Our studies show that the unusual stability of helix 109-133 is due to electrostatic interactions and probable intermolecular packing between hydrophobic faces of the amphipathic surfaces of the helices. The implications of helix formation in these fragments to a framework model of protein folding for bGH are discussed.

Amino Acid Sequence↗
PubMed1986

Analysis of plasma histamine: a modification of the enzymatic isotopic assay.

The enzymatic isotopic analysis of histamine requires extraction and concentration of [3H]-1-methylhistamine from the reaction mixture. The assay was modified to include enzymatic reaction at 0 degrees C to reduce blank values and direct application of protein-free reaction mixture to a thin-layer chromatography plate for isolating of the product. The analysis was quantitative down to 100 pg/ml of histamine, adequate for monitoring plasma histamine content.

Histamine↗
PubMed1981

Evidence for the influence of the protein-phospholipid interface on sarcoplasmic reticulum Ca++ Mg++ ATPase activity.

Sarcoplasmic reticulum from the white hind leg muscle of the rabbit was examined with 31P nuclear magnetic resonance as a nonperturbing probe of phospholipid-protein interactions in the intact membrane. The phospholipids of the sarcoplasmic reticulum appear to inhabit two distinct environments: one very similar in behavior to pure phospholipid lamellar dispersions and the other immobilized by the protein in the membrane. Measurement of the population of the latter environment suggests that it is dependent on salt concentration and probably not due to the Ca++ Mg++ ATPase of the sarcoplasmic reticulum. This immobilization can be removed completely by papain proteolysis of the membrane protein, but only partially by trypsin treatment. The phospholipid composition of recombinants with the Ca++ Mg++ ATPase was varied in order to look for effects of the phospholipid-protein interface on enzymatic activity of the Ca++ Mg++ ATPase. Both transphosphatidylated phosphatidylethanolamine (from egg phosphatidylcholine) and bovine brain phosphatidylserine readily partitioned into the putative boundary layer, whereas under the same conditions soybean phosphatidylethanolamine was excluded. Only phosphatidylserine affected the activity of the enzyme, causing an inhibition that was proportional to the phosphatidylserine content, relative to phosphatidylcholine.

Animals↗