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Biomedical subjects

A Oberg

Publications and source records attributed to A Oberg.

28 records · Page 2Linked to original sources
PubMed1990

Gingival blood flow and temperature changes in young humans with a history of periodontitis.

Whether such individuals have different gingival blood flow and temperature responses to local cooling than age- and sex-matched healthy controls was tested. Ten patients with a history of localized juvenile periodontitis or rapidly progressive periodontitis were selected from a periodontal clinic and matched with healthy controls. Gingival blood flow and temperature were monitored continuously before and after cooling via a twin probe placed in the gingival sulcus on the buccal of tooth No. 26. Blood flow was assessed by laser Doppler flowmetry and temperature by a small metal thermistor. Resting values were first recorded for 5 min, followed by 3 min of cooling to 19 degrees C by a gentle stream of cool air, then 12 min of rewarming was allowed. This protocol was repeated twice. Blood flow changes were analysed as the slope of the line formed between the last 2 min of cooling and the last 2 min of rewarming; temperature curves were analysed by a least-squares curve fit of a bi-exponential function. Patients with localized juvenile periodontitis and rapidly progressive periodontitis had similar rewarming temperature curves, but significantly faster blood flow recovery curves than controls (p less than 0.03). Thus, gingival blood flow in young periodontitis patients recovered more rapidly after local cooling than in healthy controls.

Adolescent↗
PubMed1986

Superoxide dismutase and catalase reduce infarct size in a porcine myocardial occlusion-reperfusion model.

We investigated if superoxide dismutase and catalase could reduce myocardial infarct size in an open chest occlusion-reperfusion model. Thirty pigs were used for the experiment. The left anterior descending artery was ligated for 60 min followed by a 5 h reperfusion period. After randomisation and blinding the two enzymes or placebo were injected into the left atrium as a bolus immediately before and at the end of the occlusion and as a continuous infusion over the first hour of the reperfusion period. The total dose for each enzyme was 8 mg/kg bw. Tetrazolium staining was used to determine infarct size. The study code was not broken until all calculations and exclusions had been made. Nine animals died from intractable ventricular fibrillation, most commonly during the occlusion. Another three were excluded for technical reasons. We found that superoxide dismutase and catalase reduced infarct size in relation to myocardium at risk from a mean of 89% to 63% (P less than 0.01). Initial plasma half life for the two enzymes after the bolus infusions were calculated to be 30 min.

Animals↗
PubMed1981

Fourier analysis of cardiac action potentials.

Fourier analysis of the repolarization phases of cardiac action potentials showed clear differences in the frequency characteristics of atrial and ventricular recordings. The frequency spectrum of the atrial repolarization phase was in the range of 0-45Hz, with a predominant power spectral density between 0-15Hz. The frequency spectrum of the ventricular repolarization phase was in the range of 0-20Hz, with a predominant power spectral density between 0-10Hz. Physiological changes that accentuate the differences in shape between atrial and ventricular APs also accentuate the differences in frequency spectrum of their repolarization phases. Fourier analysis therefore could be a complement to the current methods used to describe and quantify differences in the shape of cardiac action potentials.

Action Potentials↗
PubMed1977

Static and dynamic characteristics of fluid-filled esophageal manometry systems.

Esophageal manometric systems with water-filled catheters have been characterized by the use of model experiments. The examined parameters have been: catheter dimension, catheter compliance, catheter resistance, pump type, pump compliance, and perfusion flow. Accurate static pressure measurements have been obtained for perfused systems independently of the investigated parameters. The dynamic characteristics vary with catheter diameter and perfusion flow. For catheters with low diameter, a narrow bandwidth is obtained for the investigated perfusion flows. The results have been expressed in terms of an electric model of the measurement system. Perfusion pumps with low compliance are recommended to improve the dynamic properties of the measurement system.

Catheterization↗
PubMed1975

Ultramicroanalysis of metals by means of an integrating atomic absorption spectrometer and a carbon filament atom reservoir.

A fast reacting atomic absorption spectrometer in combination with a carbon filament atom reservoir was used for ultramicroanalysis of calcium and magnesium. The analysis of 1 X 10(-12) mole of magnesium gave a variation of coefficient of +/-3% and analysis of 2 X 10(-11) mole of calcium gave one of +/-5%. The effect of adding various common biological substances to the samples in great excess was tested. No interference could be observed.

Calcium↗
PubMedDate not supplied

Cytolytic capabilities of lamina propria and intraepithelial lymphocytes in normal and chronically inflamed human intestine.

Cell-mediated lymphocyte cytotoxicity in ileum and colon of patients with ulcerative colitis (UC), Crohn's disease (CD) and controls was investigated. Frequencies of cells expressing perforin and Fas-ligand (FasL) were determined by immunomorphometry. mRNA expression of perforin, granzyme B and FasL in T cells and subsets was assayed by reverse transcriptase-polymerase chain reaction. Cytotoxicity of intraepithelial and lamina propria lymphocytes was analysed without ex vivo activation in three functional assays: (1) anti-CD3-dependent T-cell receptor (TCR)-/CD3-mediated redirected cytotoxicity, (2) Fas-/FasL-mediated TCR-/CD3-independent cytotoxicity and (3) natural killer (NK) cell cytotoxicity. Inflammation in ileum of CD patients caused increased frequency of perforin-expressing cells and enhanced perforin-dependent TCR-/CD3-mediated cytotoxicity. In contrast, lymphocytes in the inflamed colon of UC or Crohn's colitis patients did not display this cytotoxicity nor did lymphocytes of normal colon. Normal colon lymphocytes showed spontaneous Fas-/FasL-mediated cytotoxicity. This activity was retained but not enhanced in inflamed UC colon. In contrast, a significant increase of FasL-expressing cells was seen in situ. Inflammation did not induce NK cell activity in colonic lymphocytes. Intestinal lymphocytes comprise effectors active in two different cytolytic processes. 'Classical' cytotoxic T lymphocytes in small intestine and lymphocytes executing TCR-/CD3-independent FasL-/Fas-mediated killing of unknown biological role present throughout the intestinal mucosa. Ongoing normal cytolytic processes seem to be enhanced by chronic inflammation.

Adult↗
PubMedDate not supplied

Limited value of preoperative serum analyses of matrix metalloproteinases (MMP-2, MMP-9) and tissue inhibitors of matrix metalloproteinases (TIMP-1, TIMP-2) in colorectal cancer.

PURPOSE: We studied whether preoperative serum levels of free MMP-2, the MMP-2/TIMP-2 complex, and total amounts of MMP-9, TIMP-1 and TIMP-2 correlated to the tumor stage and prognosis in colorectal cancer. METHODS: Samples from 158 patients operated on for colorectal cancer (100 colon, 58 rectum) and samples from 80 healthy blood donors were analyzed using an ELISA technique. One hundred and thirty-three patients were resected for cure, (31, 61, and 41 in Dukes' stages A, B, and C, respectively). At follow-up in January 1998, 44 patients had died from their cancer after a median time 14 months (range 2-55). Fifteen patients died without tumor relapse. Ninety-nine patients were alive after, a median time of 46 months (range 17-68). RESULTS: Wide, overlapping ranges were observed for all factors both in the patients and in the control group. The patients as compared to the control group had significantly higher levels of free MMP-2 and total amounts of MMP-9, TIMP-1 and TIMP-2, whereas the level of the MMP-2/TIMP-2 complex was significantly lower. TIMP-1 was significantly higher in Dukes' D compared to Dukes' A-C cases; the other factors did not correlate to tumor stage. Elevated TIMP-2 levels (median cut-off limit), only, correlated to worse prognosis when analysed in all patients (p < 0.05). None of the factors (median cut-off limit) correlated to survival in Dukes' A-C patients; analyses based on the upper quartile cut-off limit demonstrated that elevated MMP-2 levels correlated to shorter survival time (p < 0.05). CONCLUSION: Serum analyses of free MMP-2 the MMP-2/TIMP-2 complex and total amounts of MMP-9, TIMP-1 and TIMP-2 are of limited value for tumor staging and prognosis in colorectal cancer.

Adult↗