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M Van Antwerp

Publications and source records attributed to M Van Antwerp.

5 recordsLinked to original sources
PubMed2000

Use of flow cytometry to quantify mouse gastric epithelial cell populations.

Flow cytometry provides the opportunity to quantify cell populations within a total cell suspension. The quality of flow cytometry is strongly dependent on the isolation of intact viable cells. However, techniques to isolate mouse gastric cells for flow cytometry have not been evaluated. The objective of this study was to develop an effective method for isolating intact viable cells from mouse gastric tissue for flow cytometry. Cells were isolated from mouse stomach and spleen by either enzymatic separation or mechanical dissociation. A Percoll density gradient was used to separate viable cells from cellular debris. Cells were labeled with fluorescently tagged ligand or antibody and analyzed by flow cytometry. According to propidium iodide staining, there was a higher percentage of viable cells after mechanical dissociation (10-20%) compared to enzymatic separation (1%). After Percoll centrifugation there was a further increase in the percent of viable cells (50-80%). Gastrin (G), somatostatin (D), and parietal cells represented 0.6%, 3%, and 8% of the total epithelial cell population, respectively. T and B lymphocytes made up 4% and 2% in the gastric mucosa. Dissociated splenocytes were comprised of 20% T cells and 14% B cells. The ability to reliably resolve a cellular fraction that comprises only 0.6% of the input marks a substantial improvement over morphometric methods. Therefore, mechanical dissociation of the stomach followed by use of a Percoll gradient is the preferred method for isolating viable intact gastric epithelial cells for flow cytometry.

Animals↗
PubMed2000

An OmpA-like protein from Acinetobacter spp. stimulates gastrin and interleukin-8 promoters.

Bacterial overgrowth in the stomach may occur under conditions of diminished or absent acid secretion. Under these conditions, secretion of the hormone gastrin is elevated. Alternatively, bacterial factors may directly stimulate gastrin. Consistent with this hypothesis, we found that mice colonized for 2 months with a mixed bacterial culture of opportunistic pathogens showed an increase in serum gastrin. To examine regulation of gene expression by bacterial proteins, stable transformants of AGS cells expressing gastrin or interleukin-8 (IL-8) promoters were cocultured with live organisms. Both whole-cell sonicates and a heat-stable fraction were also coincubated with the cells. A level of 10(8) organisms per ml stimulated both the gastrin and IL-8 promoters. Heat-stable proteins prepared from these bacterial sonicates stimulated the promoter significantly more than the live organism or unheated sonicates. A 38-kDa heat-stable protein stimulating the gastrin and IL-8 promoters was cloned and found to be an OmpA-related protein. Immunoblotting using antibody to the OmpA-like protein identified an Acinetobacter sp. as the bacterial species that expressed this protein and colonized the mouse stomach. Moreover, reintubation of mice with a pure culture of the Acinetobacter sp. caused gastritis. We conclude that bacterial colonization of the stomach may increase serum gastrin levels in part through the ability of the bacteria to produce OmpA-like proteins that directly stimulate gastrin and IL-8 gene expression. These results implicate OmpA-secreting bacteria in the activation of gastrin gene expression and raise the possibility that a variety of organisms may contribute to the increase in serum gastrin and subsequent epithelial cell proliferation in the hypochlorhydric stomach.

Acinetobacter↗
PubMed1995

Library faculty role in problem-based learning: facilitating small groups.

Since 1986, the library faculty of the McGoogan Library of Medicine at the University of Nebraska Medical Center (UNMC) has participated in small group activities during the week-long orientation for first-year medical students. This involvement paved the way for library faculty members to act as facilitators for small groups of medical students within the new problem-based learning (PBL) curriculum introduced in 1992 by the College of Medicine. The UNMC curriculum consists of traditional PBL groups as well as Integrated Clinical Experience (ICE) small groups. The ICE groups provide opportunities for discussion of the social and behavioral issues that arise in medicine, with the majority of the sessions designed to give students interviewing practice with simulated patients. The ICE small groups meet once a week with either one or two facilitators. Several library faculty members act as facilitators for ICE groups. As a result of this involvement, librarian contacts with College of Medicine faculty have grown in number and depth, there has been a corresponding increase in related activities with the first- and second-year medical students. Participation in ICE groups has caused some difficulties with respect to library work schedules, but it has been immensely rewarding and enriching in terms of professional growth. This paper describes the UNMC curriculum, the evolution and extent of the librarians' involvement, and the future involvement, ramifications, and challenges envisioned for McGoogan faculty and their medical library colleagues.

Curriculum↗
PubMed1991

Identification of 17 independent mutations responsible for human hypoxanthine-guanine phosphoribosyltransferase (HPRT) deficiency.

Complete hypoxanthine-guanine phosphoribosyltransferase (HPRT) deficiency causes the Lesch-Nyhan syndrome, an X-linked, purine metabolism disorder manifested by hyperuricemia, hyperuricaciduria, and neurologic dysfunction. Partial HPRT deficiency causes hyperuricemia and gout. One requirement for understanding the molecular basis of HPRT deficiency is the determination of which amino acids in this salvage enzyme are necessary for structural or catalytic competence. In this study we have used the PCR coupled with direct sequencing to determine the nucleotide and subsequent amino acid changes in 22 subjects representing 17 unrelated kindreds from the United Kingdom. These mutations were confirmed by using either RNase mapping or Southern analyses. In addition, experiments were done to determine enzyme activity and electrophoretic mobility, and predictive paradigms were used to study the impact of these amino acid substitutions on secondary structure.

Chromosome Deletion↗