Biomedical subjects

D W Skagen

Publications and source records attributed to D W Skagen.

At least 19 recordsLinked to original sources

PubMed2000

Phylogeography and population history of Atlantic mackerel (Scomber scombrus L.): a genealogical approach reveals genetic structuring among the eastern Atlantic stocks.

Despite the resolving power of DNA markers, pelagic and migratory marine fish species generally show very little geographical population structuring. In mackerel (Scomber scombrus L.) population differentiation has been detected only at a transatlantic scale. By applying two regions in mitochondrial DNA (mtDNA) (D-loop and cytochrome b (cytb)) in combination with genealogical and frequency-based statistical approaches, our data suggest population differentiation among eastern Atlantic spawning stocks. In contrast, and indicative of homing behaviour, no genetic structuring was observed among shoals of individuals outside the spawning season. Among spawning stocks, mtDNA D-loop sequences detected differentiation within the eastern Atlantic, while the cytb gene detected transatlantic differentiation. The impact of recurrent events (e.g. gene flow restricted by isolation by distance) and historic events (e.g. population range expansions) among spawning stocks was investigated applying a nested cladistic analysis of geographical distribution of cytb haplotype lineages. In the eastern Atlantic, historical population range expansion, presumably in connection with recolonization of northern areas after the last glaciation, is suggested to be the main factor determining mtDNA lineage distribution. This was supported by estimates of mtDNA nucleotide diversity, where the highest diversity was observed for the stock spawning in the Bay of Biscay, for which the size estimate is only 15% of the largest stock (Celtic Sea). In addition to revealing population differentiation, our data demonstrate the importance of sampling strategy and the power of applying statistical methods addressing both ongoing and historical population processes.

Animals↗

PubMed1991

Effect of misoprostol and antacids on gastric and duodenal mucosal enzyme activities in duodenal ulcer patients.

The activities of 11 marker enzymes from the gastric and duodenal mucosa were determined in 15 patients with active duodenal ulcer disease before therapy, after 4 weeks of therapy with the prostaglandin E1 analogue misoprostol, 400 micrograms twice daily, and after another 4 weeks without any therapy. Another 15 patients were given a high-dose liquid antacid regimen. The activities were measured in homogenized material obtained with forceps through an endoscope. The healing rates of the two groups at 4 weeks were 53% and 80%, respectively. No changes in mucosal inflammation were noted during therapy. During treatment with misoprostol the activities in the descending duodenum of the membrane enzymes alkaline phosphatase, leucyl-beta-naphthylamidase, gamma-glutamyltransferase, and 5'-nucleotidase increased towards the values seen in normal controls. Despite a higher healing rate, no changes in the enzyme activities occurred in the group given high-dose antacid therapy. Four weeks after cessation of therapy the enzyme activities in the misoprostol group were not significantly different from the pretreatment values. In the biopsy specimens from the duodenal bulb the activities of monoamine oxidase fell during treatment with misoprostol and were restored to the pretreatment activity when therapy was stopped. In the stomach mucosa the enzyme activities were largely unchanged during treatment with both misoprostol and antacids. These results indicate that misoprostol and antacids have different mechanisms of action but may also suggest that the demonstrated enzymic changes are unrelated to the healing process.

Alprostadil↗

PubMed1990

Effect of ranitidine on gastric and duodenal mucosal enzyme activities in duodenal ulcer patients.

The activities of 11 marker enzymes from the gastric and duodenal mucosa were determined in 19 patients with active duodenal ulcer disease (DU) before therapy, after 4 weeks of therapy with ranitidine, 300 mg/day, and after another 4 weeks without treatment. The activities were measured in homogenized material obtained with forceps through an endoscope. The healing rate at 4 weeks was 68%. In the descending duodenum the activities of the membrane enzymes increased during the treatment period compared with pre-treatment activities. Although not as extensive as in the descending duodenum, an increase of membrane enzyme activities was also noted in the duodenal bulb during treatment. In the gastric mucosa only minor enzymic activity changes were seen. The altered enzyme activities in duodenum and stomach during treatment were independent of ulcer healing, smoking, antacids, and mucosal inflammation. Previously, significant differences in mucosal enzyme activities have been demonstrated between DU patients and controls. During ranitidine treatment the enzyme activities in the duodenal mucosa of the same DU patients tended to normalize, whereas they were mostly unchanged in the gastric mucosa. Four weeks after treatment the mucosal enzyme activities in the duodenum were as before treatment started, without occurrence of ulcer relapse. The altered enzymic activities of the duodenal mucosa in DU patients therefore seem to be largely independent of the presence of active ulcer.

Adult↗

PubMed1990

Enzyme activities in the gastric mucosa in duodenal ulcer patients.

In a series of 45 consecutive duodenal ulcer patients (DU) the activities of 10 marker enzymes from the brush border, basolateral membrane, mitochondria, and lysosomes were determined by analysis of homogenized material taken with biopsy forceps through an endoscope from the antral and body part of the stomach. They were compared with the enzyme activities determined in controls with similar types of gastritis but without any evidence of peptic ulcer disease. All the DU patients had gastritis in the antral mucosa. In the body part, about 30% had gastritis. In the antral mucosa of DU patients the activities of the membrane and lysosomal enzymes were mostly increased when compared with the controls. In the gastric body mucosa of DU patients the activities of the lysosomal enzymes were mostly increased, whereas most of the membrane enzymes showed unchanged activities when compared with the corresponding controls. Monoamine oxidase activities were decreased or unaltered in both regions in these patients. The finding of enzymatic changes in the gastric mucosa of DU patients gives further support to an altered mucosal metabolism in these patients.

Adolescent↗

PubMed1989

Enzyme activities in the duodenal mucosa in duodenal ulcer patients.

The mucosal enzyme activities of 11 marker enzymes from the brush border, basolateral membrane, and lysosomes of 45 patients with an active duodenal ulcer (DU) were determined by analysis of homogenized biopsy specimens obtained from the duodenal bulb and descending duodenum at endoscopy. They were compared with activities measured in 22 controls. In the duodenal bulb lactase (p less than 0.005), neutral-alpha-glucosidase (p less than 0.0005), and monoamine oxidase (p less than 0.0005) were significantly decreased in DU patients. In the descending duodenum all the brush border enzymes except sucrase were significantly decreased when compared with controls. DU patients with inflammation in the biopsy specimens from the duodenal bulb had decreased levels of lactase (p less than 0.05), sucrase (p less than 0.05), neutral-alpha-glucosidase (p less than 0.05), leucyl-beta-naphthylamidase (p less than 0.05), and acid phosphatases (p less than 0.05) when compared with DU patients with normal histology in this region. In the descending duodenum the activities of leucyl-beta-naphthylamidase (p less than 0.05) were decreased in patients with inflammation compared with those without such histologic changes. DU patients who had taken antacids before the investigation had decreased activities of lactase (p less than 0.05) in the descending duodenum when compared with those who had not taken antacids. Activities of lactase (p less than 0.005), sucrase (p less than 0.005), neutral-alpha-glucosidase (p less than 0.05), and acid beta-glucuronidase (p less than 0.0005) in the descending duodenum were significantly lower in smokers than in non-smokers with active DU.

Adolescent↗

PubMed1988

Estimation of running frequency spectra using a Kalman filter algorithm.

A method is suggested for the computation of running frequency spectra from non-stationary oscillations in a long time series. The method is based on an autoregressive model where the coefficients are assumed to vary slowly. The coefficients are updated using the Kalman filter technique. The method is shown to be superior to ordinary autoregressive spectral estimation based on stationary theory in recognizing rapid changes in the frequencies of oscillations.

Algorithms↗

PubMed1987

Flow cytometry of biopsy specimens from ulcerative colitis, colorectal adenomas, and carcinomas.

The cellular DNA distribution pattern in biopsy specimens from all main segments and neoplastic lesions of the large bowel, obtained from 16 patients with ulcerative colitis, 22 with adenomas, 17 with carcinoma, and 20 controls, has been studied by the flow cytometry technique. Aneuploid cell populations were demonstrated in three patients with ulcerative colitis (19%), in six with tubular adenomas (27%), and in nine with carcinoma (53%). Aneuploid cells were found in all cases of poorly differentiated adenocarcinomas. The fractional number of cells with a DNA content corresponding to the DNA synthetic and G2M phases of the cell cycle was defined as the 'proliferative index' (PI). In controls PI and its complementary G1 cell fraction varied significantly (p less than 0.005) between the segments, on the basis of analysis of variance. When compared two by two, PI was significantly higher in the sigmoid colon (p less than 0.01) and rectum (p less than 0.05) than in the ascending part. The PI of uninvolved mucosa from adenoma patients with diploid histograms was significantly higher than that in controls (p less than 0.01), ulcerative colitis (p less than 0.05), and cancer patients (p less than 0.05), when dependence on segment was taken into account.

Adenocarcinoma↗

PubMed1987

Flow cytometric DNA studies in human gastric cancer and polyps.

Flow cytometric DNA studies were performed on cell suspensions of biopsy specimens from gastric tumors and neutral gastric mucosa in 18 patients with gastric cancer and 9 patients with gastric polyps. In cancer, aneuploidy was found in two tumors in the antral and five in the body part of the stomach (39%). The mean DNA index for aneuploid cancers was 1.57. In patients with aneuploid carcinomas three biopsy specimens from uninvolved mucosa also showed aneuploidy. In diploid carcinomas in the antral part of the stomach, the proliferative index (PI) was increased when compared with that of antral mucosa in controls (p less than 0.05). Increased PI was found in uninvolved mucosa in aneuploid carcinomas of the body part of the stomach when compared with that in diploid carcinomas (p less than 0.001). In uninvolved body mucosa in aneuploid carcinomas of the body part significantly reduced levels of acid-beta-glucuronidase (p less than 0.0001) were found when compared with diploid carcinomas. No polyps showed aneuploidy, and the PI in biopsy specimens from patients with gastric polyps did not differ from that in controls.

Adult↗

PubMed1987

Flow cytometric DNA studies in normal human gastric mucosa, gastritis, and resected stomachs.

Flow cytometric measurements of cellular DNA have been performed on biopsy specimens obtained by gastroscopy in patients with normal gastric mucosa (controls), superficial and atrophic gastritis, and resected stomachs. Aneuploidy was found in two biopsy specimens from a patient with superficial gastritis and in one specimen from a resected stomach. The fractional number of cells with a DNA content corresponding to the DNA synthetic and (G2 + M) phases of the cell cycle was defined as the 'proliferative index' (PI). No difference between the antral and body part of the stomach was found for the PI in controls or between controls and superficial and atrophic gastritis. PI was weakly but significantly correlated to a selection of mucosal enzymes. In resected stomachs increased PI was found when compared with that in the body part of the stomach in controls (p less than 0.01). Biopsy specimens with intestinal metaplasia (p less than 0.01) or atrophy (p less than 0.05) in the resected stomach showed significantly higher PI when compared with specimens with such findings from the body part of the stomach in atrophic gastritis.

Adult↗

PubMed1986

Intestinal kallikrein activity is reduced in a bypassed segment of the small intestine in the rat.

The possible pancreatic origin of intestinal kallikrein was studied in a jejuno-ileal bypass model in the rat. The bypassed loops were made of variable lengths (2-72 cm) and samples were taken at 10 cm intervals to relate enzyme activities to adaptive changes caused by local and systemic stimulus. The kallikrein activity was dramatically reduced (mean 92.3%) in the bypassed loops while only moderately reduced (mean 35.8%) activities were found in the intestine remaining in continuity. Kallikrein was uniformly distributed throughout the functional small intestine in normal and bypass operated animals. The longitudinal distribution profiles obtained for brush border enzymes in normal animals were almost absent in the bypassed loops, but were apparent in the remaining intestine. The main adaptive growth was observed in the remaining small intestine, Both here and in the loop, the growth depended on the amount of bypassed tissue. Our observations are strongly in favour of a pancreatic origin of the glandular kallikrein activity found in the small intestine in the rat.

Animals↗

PubMed1986

Longitudinal distribution of mucosal enzymes in the human large bowel.

The distribution of a series of mucosal enzymes along the large bowel was studied by analysis of homogenized biopsy specimens from five different segments, obtained from 20 control patients. The activities varied significantly between the segments for the membrane enzymes lactase (p less than 0.005), alkaline phosphatase (p less than 0.0005), leucyl-beta-naphthylamidase (p less than 0.0001), and 5'-nucleotidase (p less than 0.001) and the mitochondrial enzyme monoamine oxidase (p less than 0.0005) when tested by analysis of variance modified for repeated measurements. When paired comparisons between segments were evaluated, the enzyme activities of the proximal large bowel were significantly higher than those of distal segments. The levels of sucrase, neutral-alpha-glucosidase, gamma-glutamyltransferase, and lysosomal enzymes remained unchanged throughout the large intestine, as did the protein to DNA ratio. The results are compatible with the theory that different segments of the large bowel have different functions.

Adult↗

PubMed1986

Influence of remote cancer and obesity on, and distribution of mucosal enzymes in, the upper small intestine.

A series of mucosal enzymes were estimated by analysis of homogenized biopsy specimens from the lower duodenal flexure, obtained from 10 large-bowel carcinoma patients, 15 patients with morbid obesity, and 15 controls. In 11 subjects the distribution along the upper small intestine was determined. The activities of the brush border enzymes lactase (p less than 0.01), neutral-alpha-glucosidase (p less than 0.01), and alkaline phosphatase (p less than 0.05) were significantly lower in the large-bowel carcinoma patients than in the controls. In obese subjects significantly lower activities (p less than 0.05) were demonstrated for the basolateral membrane enzyme 5'-nucleotidase and the lysosomal enzymes N-acetyl-beta-D-glucosaminidase and acid beta-glucuronidase, when compared with those in controls. Compared with the enzyme levels of the duodenal bulb, significantly higher activities of a series of enzymes were demonstrated at both the lower duodenal flexure and the angle of Treitz.

Adenocarcinoma↗

PubMed1986

Enzyme activities in biopsy specimens from human gastric mucosa.

The distribution of a series of marker enzymes in the gastric mucosa was studied by analysis of homogenized biopsy specimens from the lesser and greater curvature of the body and antrum, respectively, obtained from 11 control patients. The activities varied significantly between the regions for the membrane enzymes lactase (p less than 0.0001), neutral-alpha-glucosidase (p less than 0.005), alkaline phosphatase (p less than 0.01), leucyl-beta-naphthylamidase (p less than 0.005), and 5'-nucleotidase (p less than 0.0001) and the lysosomal enzymes N-acetyl-beta-D-glucosaminidase (p less than 0.0001) and acid beta-glucuronidase (p less than 0.0001), using analysis of variance modified for repeated measurements. When paired comparisons between regions were evaluated, the enzyme activities of the antral regions were significantly higher than those of the body stomach. The activities of gamma-glutamyltransferase, acid phosphatase, and the mitochondrial enzyme monoamine oxidase did not alter between regions, nor did the protein to DNA ratio. The demonstrated biochemical distinction between antrum and body of the stomach may be explained by different physiological and histological properties of the two parts.

Adult↗

PubMed1986

Enzyme activities in human gastric cancer and polyps.

Enzyme activities and the protein to DNA ratio in gastric biopsy specimens from patients with gastric cancer and polyps have been measured and compared with values from controls. In uninvolved mucosa in antral gastric cancer increased activities were found for several membrane and lysosomal enzymes, whereas the monoamine oxidase (MAO) activity was decreased (p less than 0.0005). In cancer tissue the MAO was also decreased (p less than 0.0003). In uninvolved mucosa in gastric cancer of the body, most membrane and lysosomal enzyme activities were increased. In the cancer tissue itself an increase in membrane enzyme activities was found for several enzymes, whereas the MAO activity was decreased (p less than 0.0001). Differences between activities in specimens from the gastric mucosa in patients with gastric polyps and those in controls were less pronounced than between gastric cancer and controls. A discriminant analysis, using the enzymes most sensitive to establish correct diagnosis, could identify normal gastric mucosa in 85-95%, atrophic gastritis in 56-63%, and uninvolved mucosa in gastric cancer in 66-78%.

Adult↗

PubMed1986

Enzyme activities in human gastric mucosa in gastritis and resected stomachs.

Biopsy specimens from the antral and body part of the stomach were studied for a range of marker enzymes in 11 patients with superficial gastritis, 9 patients with atrophic gastritis, and 31 Billroth-II-resected patients and compared with activities found in controls with normal gastric mucosa. In the antral part of the stomach increased gamma-glutamyltransferase activity was found in superficial (p less than 0.01) and atrophic gastritis (p less than 0.05), whereas monoamine oxidase activity was decreased in superficial (p less than 0.01) and atrophic gastritis (p less than 0.05). In the body part, increased activity of gamma-glutamyltransferase (p less than 0.01) and acid-beta-glucuronidase (p less than 0.01) was found in superficial gastritis. In atrophic gastritis increased activities for lactase (p less than 0.01), alkaline phosphatase (p less than 0.05), leucyl-beta-naphthylamidase (p less than 0.05), gamma-glutamyltransferase (p less than 0.05), 5'-nucleotidase (p less than 0.01), N-acetyl-beta-D-glucosaminidase (p less than 0.05), and acid-beta-glucuronidase (p less than 0.01) were found. Specimens from the gastric remnant showed an enzyme activity pattern similar to that seen in the body in atrophic gastritis, apart from a significantly decreased monoamine oxidase activity (p less than 0.004). Specimens with dysplasia in the gastric remnant showed decreased monoamine oxidase activity when compared with specimens without dysplasia (p less than 0.01).

Adult↗

PubMed1985

The effect of gastric bypass operation on glucose tolerance in obesity.

A series of variables involved in glucose handling were monitored before and after gastric bypass operation for morbid obesity. Blood glucose, insulin, C-peptide, gastric inhibitory polypeptide (GIP), pancreatic polypeptide (PP), and gastrin were measured basally and after an oral glucose load. Blood glucose, insulin, C-peptide, and PP were also measured after an intravenous glucose load. Adrenocortical function was evaluated by measuring plasma cortisol and urinary excretion of 17-hydroxy-corticosteroids and 17-ketosteroids. Nine subjects were examined before and 3 and 12 months after operation. Glucose tolerance improved postoperatively concomitant with decreased basal levels of C-peptide and insulin, increased hepatic insulin extraction, and evidence of reduced adrenocortical function. Parallel with reduced insulin resistance, support for an increase in both insulin secretion and removal was obtained postoperatively. It is concluded that the considerable endocrine abnormalities seen in morbid obesity can be normalized after gastric bypass operation and weight reduction.

Adult↗

PubMed1984

Mucosal growth and enzyme activity during the early phase of adaptation after jejunal bypass in the rat.

Morphological variables and mucosal enzyme activities were measured in the bypassed and remaining parts of the small intestine 3, 7, and 14 days after a jejunal bypass operation. In the bypassed segment tissue mass, enzyme activity per unit intestinal length, and enzyme activity per unit DNA were gradually reduced. In sham-operated animals tissue mass increased, whereas enzyme activity per unit DNA was reduced. In the segment remaining in function, tissue mass increased, whereas enzyme activities decreased temporarily. In this part of the intestine, the changes were more or less parallel in bypassed and sham-operated animals. It may be concluded that the enzymatic changes are not correlated to the morphologic changes in the early phase of adaptation to intestinal bypass.

Adaptation, Physiological↗

PubMed1983

Enzyme activities in human and rat jejunal mucosa.

To define reproducible conditions for the homogenization of small-intestinal biopsy samples, tissue homogenization has been studied by the use of three different homogenizers. Tissue samples of increasing wet weights (0.5-10.8 mg) were homogenized in a fixed volume (1 ml) before DNA and protein were determined. The DNA to protein ratio was calculated for all wet weights and used as a measure for reproducible homogenization. The minimum tissue wet weight needed for analysis (2 mg) was determined from the values obtained for the DNA to protein ratio. Highly sensitive techniques are described in detail for the assay of brush border (maltase, lactase, sucrase, neutral alpha-glucosidase, alkaline phosphatase, gamma-glutamyl transferase, leucyl-beta-naphthylamidase), basolateral membrane (5'-nucleotidase), and mitochondrial (succinate dehydrogenase) marker enzymes and for four acid hydrolases (acid phosphatase, acid beta-D-galactosidase, N-acetyl-beta-D-glucosaminidase, acid diesterase) in human and rat jejunal mucosa. Linear kinetics have been established for all enzyme assays. The optimal dilution of tissue homogenate for the assay of the various enzymes has been determined to enable the determination of a maximum number of enzymes in each homogenate. The range of enzyme activities in samples of human and rat jejunal mucosa has been determined.

Adult↗