Biomedical subjects

A D Olson

Publications and source records attributed to A D Olson.

28 records · Page 2Linked to original sources

PubMed1991

Intracellular betaine substitutes for sorbitol in protecting renal medullary cells from hypertonicity.

Renal medullary cells are normally exposed to a variably high extracellular NaCl concentration. They compensate by accumulating large amounts of organic osmolytes, including sorbitol and betaine. The sorbitol is synthesized from glucose, catalyzed by aldose reductase. Previously, inhibition of aldose reductase activity was noted to greatly reduce renal medullary cell survival and growth (measured by cloning efficiency) in tissue cultures of renal medullary cells in hypertonic medium. In contrast, inhibition of aldose reductase and renal medullary sorbitol accumulation is not associated with kidney damage in vivo. In the present experiments we find that addition of betaine to the medium, and its resultant uptake by the cells, largely replaces the decrease in sorbitol caused by aldose reductase inhibitors and restores the cloning efficiency. We presume that in vivo uptake of betaine by renal medullary cells similarly protects them from harm when aldose reductase inhibitors lower sorbitol. The results also demonstrate that one organic osmolyte can substitute for another in protecting cells from hypertonicity, consistent with the compatible osmolytes hypothesis.

Aldehyde Reductase↗

PubMed1989

Recognition properties of peptides hydropathically complementary to residues 356-375 of the c-raf protein.

Two peptides with hydropathic complementarity to residues 356-375 of the c-raf protein were synthesized to determine if they recognize the raf-(356-375) peptide as well as the entire protein. One peptide was deduced from the complementary mRNA for the raf protein corresponding to residues 356-375, whereas the other was deduced solely from the amino acid sequence of the 20-mer segment using a computer program able to generate peptide sequences with hydropathic complementarity to a given sequence. Specific binding of both peptides to the raf 20-mer segment was demonstrated when either the raf 20-mer peptide or the complementary peptides were immobilized on a column. Binding affinities were in the millimolar-micromolar range. Identical binding properties were observed with peptides synthesized with either all D- or all L-amino acids, suggesting a lack of conformational dependence. Binding was also unaffected by the presence of 8 M urea or detergents, was dependent on solvent characteristics of pH and ionic strength, and was abolished by the presence of competing peptides in the eluting buffer. Recognition between raf complementary peptides was accompanied by spectral changes in the far and near UV region, as monitored by circular dichroism. Proteolytic degradation was retarded by the binding of these peptides. Once immobilized on a column, these peptides proved useful for the isolation by affinity chromatography of a recombinant c-raf protein from an Escherichia coli crude cell extract.

Adenosine Triphosphate↗

PubMed1989

Arthritis as the initial manifestation of inflammatory bowel disease in early infancy.

We report a 10-month-old infant who had arthritis as the initial clinical manifestation of ulcerative colitis. Arthritis is considered to be the most common extraintestinal manifestation of IBD in adults and children. This case emphasizes that arthritis may be the earliest manifestation of IBD even in the very young infant.

Arthritis↗

PubMed1988

Elsie 4: quantitative computer analysis of sets of two-dimensional gel electrophoretograms.

We have developed and refined a system for quantitative computer analysis of two-dimensional polyacrylamide gel electrophoretograms. The system, named Elsie 4, is based on one described by Vo et al. (Anal. Biochem. 112, 258 (1981]. It is highly automated. Elsie 4 can find, and measure the intensity of, almost any spot resolvable on two-dimensional gels, including spots visible only as shoulders off larger spots and spots so close together that there is no "valley" between them. It can automatically match the spot patterns of different gels, potentially without the need for a user to provide landmark matches. The matches between paired gels let us follow the synthesis of any spot through a set of gels. Information about a group of matched spots can be obtained by referring to any spot in the group. There is generally no need for a standard or reference gel. Data for two experiments can be combined and compared by matching any gel in one experiment with any gel in the other. There are ways to automatically find possible mismatches in sets of gels. Scans and the results of the analysis can be shown on an image displayer. The programs use function libraries; this helps ensure consistency and increase portability. The programs and functions can be linked together in many ways; this lets users build custom programs for analysis of specific experiments.

Computer Systems↗

PubMed1987

Picking lowest-cost measurements for identifying unknowns.

One way to identify an unknown item is to measure its traits and compare the measurements with those of items the unknown might be. This paper outlines a way to pick what to measure from given known traits to (1) minimize measurement cost and (2) ensure that measuring the picked traits is as good as measuring all the given traits for purposes of identifying unknowns. The paper also relates a computer program which has been written to do this, and the program's use with the Protein Atlas in minimizing the number of amino acids to measure in an experiment involving polypeptide identification.

Amino Acid Sequence↗

PubMed1985

Differential toxicity of RCAII (ricin) on rabbit intestinal epithelium in relation to postnatal maturation.

The purpose of this work was to assess the toxic lectin ricin (RCAII) as a probe for the study of intestinal permeability in the developing small bowel. Jejunal explants from suckling and adult rabbits were exposed to varying dosages of RCAII for 30 min at 25 degrees C and then cultured in toxin-free medium. The RCAII dose required to inhibit protein synthesis during 6 h of culture increased from 0.1 microgram/ml in 4-day-old rabbits to 25 micrograms/ml in weanling rabbits. RCAII cytotoxicity was almost completely blocked by 0.1 M lactulose in all age groups. The kinetics of 125I-RCAII binding to purified microvillus membranes were determined by incubating a fixed concentration of membrane protein (30 micrograms) with increasing concentrations of labeled lectin (2-18 micrograms/ml). Binding attained saturation with adult but not with suckling animal membranes. The latter yielded a curvilinear relationship in Scatchard plots, suggesting either several classes of binding sites or negative cooperativity. RCAII binding was confined to the delipidated fraction of the membranes and decreased by 42% from 6 days old to adult age. The extreme sensitivity of colostral epithelium to RCAII is probably related to the high level of endocytosis exhibited by the immature membrane of suckling rabbits. The development of increasing resistance to the toxin, and associated decrease in binding, might be related to disappearance of saccharide sites in productive surface receptors occurring in the developmental course of intestinal glycosylation.

Animals↗

PubMed1974