| 1. |
- Hamer, H. M., et al.
(författare)
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Analyses of human colonic mucus obtained by an in vivo sampling technique
- 2009
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Ingår i: Digestive and Liver Disease. - Amsterdam : W.B. Saunders Co. Ltd.. - 1590-8658 .- 1878-3562. ; 41:8, s. 559-564
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The mucus layer is an important dynamic component of the epithelial barrier. It contains mucin glycoproteins and other compounds secreted by the intestinal epithelium, such as secretory IgA. However, a standardized in vivo sampling technique of mucus in humans is not yet available.AIM: To assess the validity and feasibility of mucin and protein determinations in human colonic mucus collected under physiological conditions.SUBJECTS AND METHODS: Triplicate colonic mucus samples were collected in 11 healthy volunteers using cytology brushes during sigmoidoscopy. As an indication of the quantity of collected mucus, total protein and mucin concentrations were determined by measuring oligosaccharide equivalents and monosaccharides. Also secretory IgA and sialic acid concentrations were determined and proteomic analysis was performed using surface enhanced laser desorption/ionization-time of flight-mass spectrometry.RESULTS: Mean values of secretory IgA and sialic acid corrected for the amount of mucus ranged from 0.16 to 1.81g secretory IgA/mmol oligosaccharide equivalents and from 12.6 to 48.6g sialic acid/mmol oligosaccharide equivalents. Proteomic analysis of mucus is feasible and cluster analysis showed subject specific profiles. CONCLUSION: Using cytology brushes, human colonic mucus can be sampled and under physiological conditions. These samples could give information on the composition and quality of the mucus layer.
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| 2. |
- Hamer, G, et al.
(författare)
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Characterization of a novel meiosis-specific protein within the central element of the synaptonemal complex
- 2006
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Ingår i: Journal of cell science. - : The Company of Biologists. - 0021-9533 .- 1477-9137. ; 119:19Pt 19, s. 4025-4032
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Tidskriftsartikel (refereegranskat)abstract
- During the first meiotic prophase, alignment and synapsis of the homologous chromosomes are mediated by the synaptonemal complex. Incorrect assembly of this complex results in cell death, impaired meiotic recombination and formation of aneuploid germ cells. We have identified a novel mouse meiosis-specific protein, TEX12, and shown it to be a component of the central element structure of the synaptonemal complex at synapsed homologous chromosomes. Only two other central element proteins, SYCE1 and SYCE2, have been identified to date and, using several mouse knockout models, we show that these proteins and TEX12 specifically depend on the synaptonemal transverse filament protein SYCP1 for localization to the meiotic chromosomes. Additionally, we show that TEX12 exactly co-localized with SYCE2, having the same, often punctate, localization pattern. SYCE1, on the other hand, co-localized with SYCP1 and these proteins displayed the same more continuous expression pattern. These co-localization studies were confirmed by co-immunoprecipitation experiments that showed that TEX12 specifically co-precipitated with SYCE2. Our results suggest a molecular network within the central elements, in which TEX12 and SYCE2 form a complex that interacts with SYCE1. SYCE1 interacts more directly with SYCP1 and could thus anchor the central element proteins to the transverse filaments.
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| 3. |
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| 4. |
- Hamer, G, et al.
(författare)
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Progression of meiotic recombination requires structural maturation of the central element of the synaptonemal complex
- 2008
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Ingår i: Journal of cell science. - : The Company of Biologists. - 0021-9533 .- 1477-9137. ; 121:15Pt 15, s. 2445-2451
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Tidskriftsartikel (refereegranskat)abstract
- The synaptonemal complex is an elaborate meiosis-specific supramolecular protein assembly that promotes chromosome synapsis and meiotic recombination. We inactivated the meiosis-specific gene Tex12 and found that TEX12 is essential for progression of meiosis in both male and female germ cells. Structural analysis of the synaptonemal complex in Tex12–/– meiocytes revealed a disrupted central element structure, a dense structure residing between the synapsed homologous chromosomes. Chromosome synapsis is initiated at multiple positions along the paired homologous chromosomes in Tex12–/– meiotic cells, but fails to propagate along the chromosomes. Furthermore, although meiotic recombination is initiated in Tex12–/– meiotic cells, these early recombination events do not develop into meiotic crossovers. Hence, the mere initiation of synapsis is not sufficient to support meiotic crossing-over. Our results show that TEX12 is a component of the central element structure of the synaptonemal complex required for propagation of synapsis along the paired homologous chromosomes and maturation of early recombination events into crossovers.
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| 5. |
- Hamer, Henrike M., et al.
(författare)
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Butyrate modulates oxidative stress in the colonic mucosa of healthy humans
- 2009
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Ingår i: Clinical Nutrition. - Amsterdam : Churchill Livingstone. - 0261-5614 .- 1532-1983. ; 28:1, s. 88-93
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND & AIMS: Butyrate, a short-chain fatty acid produced by colonic microbial fermentation of undigested carbohydrates, has been implicated in the maintenance of colonic health. This study evaluates whether butyrate plays a role in oxidative stress in the healthy colonic mucosa. METHODS: A randomized, double blind, cross-over study with 16 healthy volunteers was performed. Treatments consisted of daily rectal administration of a 60 ml enema containing 100 mM sodium butyrate or saline for 2 weeks. After each treatment, a blood sample was taken and mucosal biopsies were obtained from the sigmoid colon. In biopsies, the trolox equivalent antioxidant capacity, activity of glutathione-S-transferase, concentration of uric acid, glutathione (GSH), glutathione disulfide and malondialdehyde, and expression of genes involved in GSH and uric acid metabolism was determined. Secondary outcome parameters were CRP, calprotectin and intestinal fatty acid binding protein in plasma and histological inflammatory scores. RESULTS: Butyrate treatment resulted in significantly higher GSH (p<0.05) and lower uric acid (p<0.01) concentrations compared to placebo. Changes in GSH and uric acid were accompanied by increased and decreased expression, respectively, of their rate limiting enzymes determined by RT-PCR. No significant differences were found in other parameters. CONCLUSIONS: This study demonstrated that butyrate is able to beneficially affect oxidative stress in the healthy human colon.
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