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Biomedical subjects

P Aman

Publications and source records attributed to P Aman.

At least 55 records · Page 3Linked to original sources
PubMed1996

Expression patterns of the human sarcoma-associated genes FUS and EWS and the genomic structure of FUS.

FUS (TLS) was first identified as the 5'-part of a fusion gene with CHOP (GADD153, DDIT3) in myxoid liposarcomas with t(12; 16)(q13; p11). Homologies were found with the EWS oncogene, which is rearranged in Ewing sarcomas and other neoplasias. The genomic structure of FUS shows extensive similarities with that of EWS, but the exon/intron structures differ in the 5' parts, and overall FUS is smaller than EWS. Exon 3 of FUS corresponds to exons 3 and 4 in EWS. FUS exons 4-6 correspond to EWS exons 5-8. Exons 7 to 15 of FUS are very similar to those in EWS, although the EWS exons are larger than the corresponding FUS exons. FUS and EWS were expressed in all tissues investigated. The transcripts were stable within the 160-min half-life experiments. No or little variation in FUS or EWS expression was seen when resting lymphocytes were activated. These observations indicate that FUS and EWS belong to the housekeeping type of genes. This view is supported by the presence of the housekeeping gene type of promoter region in both genes.

Amino Acid Sequence↗
PubMed1996

Duplication of chromosome segment 12q15-24 is associated with atypical lipomatous tumors: a report of the CHAMP collaborative study group. CHromosomes And MorPhology.

Ordinary lipomas are cytogenetically characterized by a variety of balanced rearrangements involving chromosome segment 12ql3-15, and atypical lipomatous tumors (ALT) by supernumerary ring chromosomes or giant markers known to contain amplified 12q sequences. In a series of 228 cytogenetically analyzed and histopathologically reexamined ordinary lipomas and ALT, 10 tumors showed unbalanced chromosome-12 aberrations. All 4 tumors with loss of segments from 12q were classified as ordinary lipomas, whereas 5 of the 6 tumors showing gain of 12q material were diagnosed as ALT. One or three extra copies of 12q15-q24 were present in all 5 ALT. We conclude that duplication of 12q sequences may be a sufficient level of amplification for development of the microscopic appearance that characterizes ALT.

Chromosome Aberrations↗
PubMed1996

Structural features of an arabinan fragment isolated from the water-soluble fraction of dehulled rapeseed.

A water-soluble polysaccharide fraction was prepared from dehulled rapeseed meal (winter rapeseed variety Casino). Further purification yielded two major fractions having a high content of arabinose and galactose residues, with Ara/Gal ratios of 5.4 (G1) and 1.8 (G2). The Ara/Gal ratio of the high molecular weight fraction G1 was stable over the whole gel filtration peak, indicating that the arabinose and galactose residues are part of the same polysaccharide. The high molecular weight fraction G1 was studied further by methylation analysis and several NMR techniques. Structural studies showed G1 to consist mainly of arabian fragments, which have terminal alpha-L-arabinofuranosyl groups with anomeric carbons bound (1-->5) (A) or (1-->2) (B), and 2,5-substituted arabinosyl residues with anomeric carbons bound (1-->5) (D) or (1-->2) (C) to adjacent arabinosyl residues. The A:B:C:D ratios were 2:1:1:1 according to results from NMR and methylation analysis.

Arabinose↗
PubMed1996

Fusion of the EWS and CHOP genes in myxoid liposarcoma.

The translocation t(12;16)(q13;p11), which cytogenetically characterizes myxoid liposarcomas (MLS), results in a fusion of the CHOP gene in 12q13 and the FUS gene in 16p11, creating a chimeric FUS/CHOP gene. We have identified two cases of MLS with translocations giving rise to recombination between 12q13 and 22q12. The result was a fusion of the N-terminal part of the EWS gene in 22q12, involved in a number of mesenchymal tumor types, with the CHOP gene and the creation of an EWS/CHOP chimeric gene. The presence of the EWS/CHOP chimeric gene in MLS shows that (i) the N-terminal part of FUS may be replaced by the N-terminal part of EWS in a CHOP fusion oncoprotein (ii) the two N-terminal parts, when fused to certain transcription factors, have a common or very similar oncogenic potential and (iii) the tumorigenic process in MLS and the morphogenetically distinctly different EWS-associated tumor types may be related.

Amino Acid Sequence↗
PubMed1996

Genomic PCR detects tumor cells in peripheral blood from patients with myxoid liposarcoma.

Myxoid liposarcoma (MLS) is the most common subtype of liposarcoma. The cytogenetic hallmark of MLS is the pathognomonic t(12;16)(q13;p11), present in more than 85% of cases. The translocation leads to the fusion of the CHOP and FUS genes at 12q13 and 16p11, respectively, and the generation of a FUS/CHOP hybrid protein. The presence of a tumor-specific chimeric gene makes it possible to identify MLS cells by polymerase chain reaction (PCR). We have analyzed peripheral blood samples obtained during a 10-year period at diagnosis of primary and/or recurrent disease in 19 MLS patients with t(12;16) and in one MLS patient with t(12;22;20), resulting in the fusion of the CHOP and EWS genes. Nested PCR on genomic DNA from blood samples amplified FUS/CHOP hybrid fragments in three patients and EWS/CHOP in the patient with t(12;22;20). There was no obvious association between PCR findings and clinical outcome, but larger series are needed to draw any firm conclusions.

Adult↗
PubMed1996

No genetic linkage between multiple sclerosis and the interferon alpha/beta locus.

Multiple sclerosis (MS) is probably caused by an interaction of genetic and environmental factors. The genetic component is reflected by a ten-fold higher concordance rate in monozygotic (27%) compared to dizygotic (3%) twin pairs. Treatment with interferon was recently reported to have a favorable effect in patients with relapsing-remitting MS. In the present familial study, we have investigated the possibility of a genetic association between the highly polymorphic Interferon alpha beta locus and the development of MS. Based on our data, we conclude that there is no linkage between the Interferon alpha beta locus and MS.

Adult↗
PubMed1996

Substrates available for colonic fermentation from oat, barley and wheat bread diets. A study in ileostomy subjects.

Nutrients not absorbed in the small bowel will form substrates for microbial growth in the colon which may have implication for the development of colon cancer. The aim of the present study was to investigate whether fibre-rich oat and barley diets increase the excretion of energy-supplying nutrients from the small bowel compared with a low-fibre wheat diet, and whether a possible increase could be related to the beta-glucan content. Nine ileostomy subjects were served four types of bread together with a low-fibre basal diet (12 g dietary fibre/d). The breads were based on either wheat flour (W diet, 7 g dietary fibre/d), oat bran (OB diet, 29 g dietary fibre/d), the same amount of oat bran with addition of beta-glucanase (EC 3.2.1.4) (OBE diet, 19 g dietary fibre/d) or a fibre-rich barley fraction (B diet, 35 g dietary fibre/d). An increased ileal excretion of starch was observed with the barley diet but no effect of the oat beta-glucan on starch recovery was found. The NSP + Klason lignin in the ileostomy effluents accounted only for 24, 31, 24 and 35% of the gross energy excretion in the W, OB, OBE and B diet periods respectively. A large part of the dry weight and energy (30, 21, 28 and 27%, in the W, OB, OBE and B diets respectively) in the effluents could not be identified as fat, protein, total starch or NSP + Klason lignin. This unidentified part was probably made up of oligosaccharides, endogenous losses and nutrient complexes. Methods for identifying and analysing these components should be developed and their role as substrates for colonic fermentation and colon cancer development ought to be investigated.

Adult↗
PubMed1996

Mixed-linked beta-glucan from breads of different cereals is partly degraded in the human ileostomy model.

The purpose of this investigation was to study the degradation of beta-glucan in the small intestine and the molecular weight of beta-glucan in the excreta of nine ileostomy subjects after consumption of different diets based on bread made with oat bran (oat bread), a fiber-rich barley fraction (barley bread), or wheat flour (wheat bread) as the main ingredients. Oat bread with enzymatically degraded beta-glucan was also used (oat + enzyme bread). The beta-glucan intake from the four diets was 12.5, 12.9, 1.1, and 4.0 g/d, respectively. On the basis of dry matter, the night effluents accounted for approximately 15% of the total amount of the excreta, with the highest proportion (22%) being for the wheat-bread diet. A notable loss of beta-glucan (0.7-2.4 g/d, or 13-64%) was found when intake was compared with excretion. In vitro, a higher viscosity development with time for dispersions of oat bread compared with barley bread was noted, which could be related to the higher molecular weight of the beta-glucan in this bread. There seemed to be a depolymerization of the beta-glucan both during bread making and transit through the upper gastrointestinal tract.

Adult↗
PubMed1996

Intake of rye bread ileostomists increases ileal excretion of fiber polysaccharide components and organic acids but does not increase plasma or urine lignans and isoflavonoids.

The excretion of starch, enzyme-resistant starch, dietary fiber components and organic acids (short-chain fatty acids plus lactic acid) as well as plasma and urine lignans and isoflavonoids was studied in eight ileostomists consuming mixed diets with wheat bread (low fiber diet) or rye bread (high fiber diet) in a crossover design. Average ileal excretions of enzyme-available starch were 3.5 g/d during the low fiber period and 4.1 g/d during the high fiber period. The excretion of enzyme-resistant starch was approximately the same (2.3 g/d) in both periods. In comparison with intake, similar amounts of total fiber residues were excreted both by subjects receiving the low fiber diet (3.4 g/d) and by those receiving the high fiber diet (2.7 g/d). However, subjects excreted significantly more of certain polysaccharide residues (fucose, galactose, and uronic acids) than they ingested. On average, the excretion of organic acids was 18.6 mmol/d during the low fiber period and 30.2 mmol/d during the high fiber period. No significant differences in plasma lignans were observed between the high fiber and the low fiber dietary periods. The present findings indicate that enzyme-available starch is highly digested and that a microbial breakdown of dietary fibers and probably other carbohydrates occurs in the small intestine. However, the bacterial activity in the ileostomists was not sufficient to cause an increased level in plasma lignans even when subjects consumed the high fiber rye diet.

Adult↗
PubMed1996

The immunoregulatory mediator macrophage migration inhibitory factor (MIF) catalyzes a tautomerization reaction.

BACKGROUND: Recent studies of melanin biosynthesis have uncovered an unusual enzymatic activity which converts the non-naturally occurring D-isomer of 2-carboxy-2,3-dihydroindole-5,6-quinone (dopachrome) into 5,6-dihydroxyindole-2-carboxylic acid (DHICA). The aim of the present investigation was to isolate and characterize the enzyme catalyzing this tautomerization reaction. MATERIALS AND METHODS: After we performed a tissue survey of D-dopachrome tautomerase activity, 10 bovine lenses were homogenized and used as a source of enzyme. A soluble fraction was obtained by high-speed centrifugation and subjected to successive FPLC chromatography on Phenyl-sepharose, Mono S cation-exchange, and Superdex gel-filtration. The isolated enzyme was electrophoresed, blotted onto PVDF membrane, and the N terminus analyzed by gas phase micro-sequencing. RESULTS: The protein catalyzing the conversion of D-dopachrome to DHICA was purified to homogeneity in 14% yield and showed a molecular weight of 12 kD when analyzed by SDS-PAGE. The first 27 amino acid residues of this protein were sequenced and found to be identical with those of bovine macrophage migration inhibitory factor (MIF). The catalytic activity of native MIF was confirmed by studies of purified recombinant human MIF, which showed the same tautomerase activity. While L-dopachrome was not a substrate for this reaction, the methyl esters of the L- and D-isomers were found to be better substrates for MIF than D-dopachrome. CONCLUSIONS: MIF has been described recently to be an anterior pituitary hormone and to be released from immune cells stimulated by low concentrations of glucocorticoids. Once secreted, MIF acts to control, or counter-regulate, the immunosuppressive effects of glucocorticoids on the immune system. Although the tested substrate, D-dopachrome, does not occur naturally, the observation that MIF has tautomerase activity suggests that MIF may mediate its biological effects by an enzymatic reaction. These data also offer a potential approach for the design of small molecule pharmacological inhibitors of MIF that may modulate its potent immunoregulatory effects in vivo.

Amino Acid Sequence↗
PubMed1995

Cloning and sequencing of a cDNA encoding rat D-dopachrome tautomerase.

An enzyme which converts D-dopachrome into 5,6-dihydroxyindole has recently been isolated from rat liver. Enzymatic D-dopachrome conversion has been observed in extracts from all tissues examined of several species, including man. We have now cloned and sequenced a 628 bp long cDNA encoding the enzyme provisionally called D-dopachrome tautomerase. The cDNA was isolated by 3' and 5' rapid amplification and cloning of cDNA ends (RACE) from rat liver cells using degenerate oligonucleotide primers, deduced from the N-terminal peptide sequence of D-dopachrome tautomerase. The cDNA contains an open reading frame encoding 118 amino acids. Edman degradation of intact and of trypsin degraded D-dopachrome tautomerase fragments gave information on and corroborated 67% of the deduced protein sequence. A homology search in the EST database found a human cDNA encoding a peptide sharing 66% homology with the rat enzyme. The rat D-dopachrome tautomerase shares 27% homology with the rat macrophage migration inhibitory factor (MIF).

Amino Acid Sequence↗
PubMed1995

Two distinct FUS breakpoint clusters in myxoid liposarcoma and acute myeloid leukemia with the translocations t(12;16) and t(16;21).

The FUS gene, which maps to 16p11, is fused to the CHOP gene in the t(12;16) (q13;p11) that characterizes myxoid liposarcomas (MLS) and to the ERG gene in acute myeloid leukemia (AML) with t(16;21) (p11;q22). In the present study we have mapped the breakpoints within FUS in 13 MLS with t(12;16) and in one AML with t(16;21). This region of FUS is about 3.9 kb and contains four exons. The breakpoints clustered to two zones (1 and 2). A strong association was found between the two known types of FUS/CHOP transcripts and the genomic localization of the breakpoints. In all cases expressing only type I or both type I and II FUS/CHOP transcript the genomic breakpoints mapped to zone 1. In all cases expressing only the type II transcript the breakpoints occurred in zone 2. The breakpoint in the AML case was in zone 1, suggesting that in-frame fusion transcripts are selected by similar mechanisms in both MLS and AML.

Base Sequence↗
PubMed1995

Oat beta-glucan increases bile acid excretion and a fiber-rich barley fraction increases cholesterol excretion in ileostomy subjects.

The purpose of this study was to investigate whether oat beta-glucan is responsible for the increased bile acid excretion previously observed with oat-fiber diets. The excretion patterns in ileostomy subjects given diets containing oat-bran bread with and without added beta-glucanase, a beta-glucan-degrading enzyme, were compared. The effect of a beta-glucan-rich barley fraction on sterol excretion was also investigated. Nine ileostomy subjects were served four diets in random order, each diet for 2 consecutive days. Four different kinds of bread, mainly made from oat bran (OB diet, 12.5 g beta-glucan/d), oat bran with beta-glucanase (OBE diet, 3.8 g beta-glucan/d), barley (B diet, 13.0 g beta-glucan/d), or wheat flour (W diet, 1.2 g beta-glucan/d) were added to a basal diet. The 24-h excretion of bile acids was 53% higher in the OB diet period than in the OBE diet period (P < 0.05) and also was significantly higher than in the B and W diet periods (P < 0.05). Median (range) bile acid excretion was 851 (232-1550), 463 (123-1414), 755 (133-1187), and 606 (101-980) mg/d in the OB, OBE, B, and W diet periods, respectively. The excretion of cholesterol was significantly higher in the B diet period than in the OBE and W diet periods (P < 0.05), but the mechanism behind this effect of barley fiber is unknown. In oat bran, however, beta-glucan mediates an increase in bile acid excretion, which most probably explains the effect of oat fiber in lowering serum lipids.

Adult↗
PubMed1995

Starch and dietary fiber components are excreted and degraded to variable extents in ileostomy subjects consuming mixed diets with wheat- or oat-bran bread.

The study was conducted to determine if the excretion of starch and dietary fiber components varies in ileostomy subjects consuming diets high or low in dietary fiber. Excretion of starch, enzyme-resistant starch and dietary fiber components was studied in nine human subjects with ileostomies, who consumed (in a crossover design) a wheat bread-based diet (daily intake 274 g starch, 2.4 g enzyme-resistant starch and 14.4 g total dietary fiber) and a high fiber diet based on oat-bran bread (daily intake 243 g starch, 2.7 g enzyme-resistant starch and 40.2 g total dietary fiber). Food and excreta were collected on d 3 and 17. No significant differences in excretion of starch, enzyme-resistant starch or dietary fiber components were found on these 2 d in each dietary period. When subjects consumed the wheat bread-based diet they excreted (mean +/- SD) 3.3 +/- 1.7 g starch and 2.4 +/- 0.4 g enzyme-resistant starch daily, whereas when consuming the oat bran-based diet they excreted 4.5 +/- 3.1 g starch and 2.5 +/- 0.4 g enzyme-resistant starch. During both dietary periods subjects excreted significantly greater amounts of certain dietary fiber polysaccharide residues (fucose, galactose and uronic acid) than they ingested. This indicates a contribution of endogenous and/or microbial material to the dietary fiber value in ileostomy effluents. However, significantly less excretion of some dietary fiber polysaccharide residues, especially glucose residues, during the oat-bran bread-based dietary period was also noted. This was presumably caused by a degradation of mixed-linked (1,3),(1,4)-beta-D-glucans.

Adult↗
PubMed1995

Trisomy 7 in nonneoplastic epithelial kidney cells.

Trisomy 7 has been found as the sole clonal chromosome aberration in a number of tumor types, including renal cell carcinomas (RCC), and also in non-neoplastic kidney tissue. It has recently been proposed that the cells harboring trisomy 7 in RCC and in the surrounding tissue may be tumor infiltrating T-helper lymphocytes. We performed cytogenetic analysis of metaphase cells and FISH of interphase nuclei in uncultured and cultured non-neoplastic kidney tissues from 13 patients with renal or urothelial carcinomas, and 4 patients with inflammatory kidney diseases. FISH analysis showed that the frequency of +7 varied between 1.0-8.9% (mean 3.3%) in uncultured cells and between 0.4-8.6% (mean 4.4%) after one week of cell culture. The frequency of +7 after one week of culture was 1.0-19.0% (mean 6.1%) as determined by cytogenetic analysis. Immunoenzymatic staining of both uncultured and cultured cells with the alkaline phosphatase reaction and monoclonal antibodies for CD3 showed that the frequency of T-cells in uncultured cells and in primary cultures varied between 2.9-10%. The number of T-cells decreased with time and number of in vitro passages to less than 1% after 7-8 weeks, but the frequency of +7 remained fairly constant. Combination of FISH with immunostaining using CD3 for T-lymphocytes and cytokeratins for epithelial cells showed that the cells with +7 were mainly epithelial cells whereas only 0-5% were T-lymphocytes. The results have obvious implications for the interpretation of the significance of trisomy 7 in neoplasia.

Adult↗
PubMed1995

Isolation and characterization of radiation hybrids for human chromosome 12.

We have used an irradiation and fusion procedure to generate somatic cell hybrids that maintain fragments of human chromosome 12. To identify hybrids retaining human material we performed repeat element-mediated PCR (intra-ALU PCR) on DNA extracted from individual cell clones. Twenty-five of 38 hybrids tested were shown to contain human material at low passage. These were further characterized by inter-ALU and inter-LI PCR. FISH analysis, using human Cot1 DNA as a probe, revealed the presence of 1-2 fragments in 11 out of 12 hybrids. The majority of the hybrids, 8 out of 12, were found to be homogeneous. The hybrid panel was characterized by 18 markers with known locations covering the entire chromosome 12. Thirteen of the 25 hybrids were positive for at least one marker. The results indicated the following order of loci on 12q: Cen-WNTI-A2MR-RAP1B-D12S8-PTBR-ATP2B1++ +-D12S7-D12S52-IGF1-PAH-PLA2-IFNG-ALDH2-te r. Three hybrids studied in more detail were found to carry overlapping fragments from chromosome segment 12q12-->q14.

Animals↗
PubMed1995

Excretion of amino acid residues from diets based on low-fibre wheat or high-fibre rye bread in human subjects with ileostomies.

OBJECTIVES: The effect of consumption of a wheat-flour bread-based low-fibre diet (13.6 g/day fibre per portion) or a rye bran bread and whole-grain rye crispbread-based high-fibre diet (43.5 g/day fibre per portion) on the ileal excretion of amino acid residues and crude protein was studied. DESIGN: The study was performed as a cross-over design. SETTING: The subjects were studied as outpatients except on the sampling days when all subjects were admitted to the research ward and stayed in a nearby patient hotel overnight. SUBJECTS: Six men and two women, all proctocolectomised for ulcerative colitis, volunteered to participate in the study. INTERVENTIONS: During each dietary period of 3 weeks, food and excreta were collected and analysed on days 3, 17 and 18. RESULTS: The excretion of crude protein and amino acids (free and bound) was generally higher during the high-fibre diet period, although the relative proportion of amino acids was similar in the ileal effluents from the two diets. The apparent digestibilities of crude protein and all amino acids except histidine, tyrosine and proline were significantly (P < 0.05) lower during the high-fibre diet period. CONCLUSION: It was indicated that the effect of the high-fibre rye-based diet was a generally impaired ileal amino acid absorption.

Aged↗