Biomedical subjects

W Rolfsen

Publications and source records attributed to W Rolfsen.

At least 19 recordsLinked to original sources

PubMed1999

Subjective gastrointestinal tolerability of acetylsalicylic acid and paracetamol after single dose treatment.

UNLABELLED: A prospective, randomised, double-blind, parallel group, two center, single-dose study was conducted to evaluate and compare the incidence of upper gastrointestinal complaints of acetylsalicylic acid and paracetamol. 600 healthy volunteers received acetylsalicylic acid (2 effervescent tablets of 400 mg), paracetamol (2 effervescent tablets of 500 mg) or placebo (2 effervescent tablets) in three treatment groups. Subjects filled in a questionnaire at 0.5, 1, 2, 3 and 4 h after dosing to evaluate eight upper gastrointestinal symptoms, which were stomach pain, burning sensation, nausea, heartburn, gas, burping, indigestion and upset stomach. The primary study objective was to show equivalence between acetylsalicylic acid and paracetamol. RESULTS: The absolute number of subjects reporting gastrointestinal intolerance were 50 of 200 in the placebo group, 46 of 200 in the paracetamol group and 56 of 201 in the acetylsalicylic acid group. The statistical test showed equivalence between both active substances. CONCLUSION: The rate of gastrointestinal intolerance following a single dose of two effervescent tablets of acetylsalicylic acid is equivalent to that of paracetamol and not different from gastrointestinal intolerance of placebo.

Acetaminophen↗

PubMed1997

The flavonoid constituents of two Polypodium species (Calaguala) and their effect on the elastase release in human neutrophils.

Five flavonoid compounds were isolated from two Polypodium species (P.decumanum and P.triseriale) with the common name Calaguala. Structure elucidation was carried out using different NMR techniques and revealed the presence of one new glycoside (kaempferol 3-O-beta-D-xylopyranosyl-(1-2)-beta-D-arabinopyranoside) (1), two known flavonoid glycosides, rutin and kaempferol 3-O-alpha-D-arabinopyranoside (2,3), the trimeric proanthocyanidin, selligueain (4), and the coumarinic acid derivative, melilotoside (5). The compounds were tested for their activity in PAF induced exocytosis in human neutrophils but none of the compounds showed PAF specific activity. Instead, they showed more general effects on the neutrophil including inhibition of the spontaneous elastase release (5) and potentiation of the release induced by PAF (1). Selligueain was found to inhibit the proteolytic enzyme, elastase in vitro.

Cells, Cultured↗

PubMed1997

A sulphonoglycolipid from the fern Polypodium decumanum and its effect on the platelet activating-factor receptor in human neutrophils.

The South American fern Polypodium decumanum, traditional name calaguala, has documented clinical use in oral treatment of skin disorders, including psoriasis. The inflammatory mediator platelet-activating factor (PAF), has been implicated in the pathogenesis of psoriasis. A constituent of a calaguala extract has been shown to have inhibitory activity in a PAF-induced exocytosis model in human neutrophils. The compound was identified as the sulphoquinovosyl diacylglycerol 1,2-di-O-palmitoyl-3-O-(6-sulpho-alpha-D-quinovopyranosyl)-glycero l by spectroscopic means. When subsequently studied in an in-vitro model for [3H]PAF binding in neutrophils from man the compound caused dose-dependent displacement of [3H]PAF from its receptor with an IC50 value of 2 microM. It is suggested that the compound acts through PAF receptor antagonism in intact human neutrophils.

Exocytosis↗

PubMed1994

Receptors for hyaluronan on corneal endothelial cells.

Previous investigations suggest that the corneal endothelium has specific binding sites for hyaluronan (HYA). In the present study, biochemical and immunological techniques were used to characterize these binding sites and to compare them with the liver endothelial cell (LEC) HYA receptor. Affinity chromatography of solubilised, 125I-labelled corneal endothelial cell surface proteins on immobilised HYA proved that there were molecules that were strongly bound to the polysaccharide. A part of these molecules formed a 100-kDa band when analysed by autoradiography after SDS polyacrylamide electrophoresis (PAGE). A specific antibody against the rat LEC HYA receptor was used for immunohistochemical studies of monkey and human corneas. There was a specific staining of the corneal endothelium of both species, and hyaluronan treatment before isolation of the human eyes reduced the staining intensity. Hyaluronidase treatment of the tissue sections before receptor staining strikingly increased the specific staining of the corneal endothelial cells (CEC). Immunoblotting of human corneal proteins, separated by SDS-PAGE, showed staining at 200, 150-160 and 55 kDa. Uptake experiments of tritiated HYA in cultured monkey CEC showed only a slight increase in cell associated radioactivity over 2-6 hr. The results make it unlikely that the corneal endothelial receptor, like its liver endothelial counterpart, is actively involved in receptor-mediated endocytosis. Our studies suggest that CEC carry receptors for HYA that are immunologically similar to the LEC receptors. CEC receptors might act as binding structures increasing the concentration of HYA close to the CEC as a protection of these vulnerable cells from physicochemical damage.

Animals↗

PubMed1994

The fern Polypodium decumanum, used in the treatment of psoriasis, and its fatty acid constituents as inhibitors of leukotriene B4 formation.

The fern Polypodium decumanum, commonly called Calaguala, has a clinically documented use in South America and Spain in the treatment of psoriasis. One of the inflammatory mediators isolated in abnormally high quantities in the psoriatic skin is leukotriene B4 (LTB4). Calaguala was tested in an in vitro model using human leukocytes for its ability to inhibit the LTB4 formation. The inhibition was found to be caused by the polyunsaturated fatty acids (PUFAs) linoleic, linolenic and arachidonic acid. IC50 values were determined for the isolated acids and compared to a group of closely related acids also commonly found in nature. The IC50 values for most acids tested were of the same magnitude (20-60 microM) except for arachidonic acid which showed stimulatory activity and 8(R) hydroxylinoleic acid which gave 30% inhibition with the highest dose tested (120 microM). The amounts of PUFAs in different Calaguala extracts were quantitatively analysed and it is concluded that the fatty acid constituents of Calaguala may contribute to the clinical effects of the extract.

Chromatography, High Pressure Liquid↗

PubMed1993

Histochemical identification of hyaluronan in the rabbit anterior segment during the healing period after extracapsular lens extraction.

Extracapsular lens extractions were performed in rabbits. The eyes were examined at different time intervals after surgery with a histochemical method visualizing hyaluronan. There was positive staining for hyaluronan in the wound region from 2 to 90 days postoperatively. The staining was most intense and widespread between 7 and 14 days after surgery. A hyaluronan staining in the corneal stroma extended from the wound towards the central cornea 4 to 14 days postoperatively. The iris showed increased staining on the second postoperative day, but much less so at the other times studied. Cells on the posterior lens capsule were surrounded by hyaluronan from the seventh postoperative day throughout the observation time up to 90 days postoperatively. It is concluded that hyaluronan reacts during corneal wound healing.

Animals↗

PubMed1993

Formation of free radicals during phacoemulsification.

During phacoemulsification cavitation bubbles are formed. These bubbles are believed to be one source of damage to corneal endothelium seen after phacoemulsification. Free radicals are induced whenever cavitation bubbles implode. The aim of this study was to confirm the initiation of free radicals by phacoemulsification and to correlate the power of ultrasound in the phacoemulsification process to the amount of free radicals formed, using both in vitro and in vivo techniques. The formation of free radicals was determined by adding luminol to a buffer and measuring the chemoluminescence in vitro and in rabbit eyes (Lumacounter 2080 or a single-photon-counting apparatus) during phacoemulsification. The data obtained show that free radicals are formed during phacoemulsification and that the amount of free radicals correlates with the power of ultrasound. Furthermore, the radical formation could be inhibited by the radical scavengers SOD, Healon and Healon GV. These results were achieved both in vitro in the test tube and in vivo in rabbit eyes. By showing that the addition of SOD to the irrigation buffer during phacoemulsification decreases the corneal endothelial cell damage, we show that free radicals could have a role in postoperative complications seen clinically.

Animals↗

PubMed1992

Binding of strychnocarpine and related beta-carbolines to brain receptors in vitro.

The affinity of strychnocarpine and related beta-carbolines for serotonin, benzodiazepine, tryptamine, opiate and GABA receptors in rat brain was studied. Strychnocarpine showed a low to very low affinity for all the receptors tested. The weak binding to tryptamine receptors might explain part of the tremorigenic effects found earlier in the in vivo studies.

Animals↗

PubMed1992

Cellular reaction following cataract surgery with implantation of the heparin-surface-modified intraocular lens in rabbits with experimental uveitis.

The inflammatory response after cataract surgery and intraocular lens (IOL) implantation was studied in rabbits with endotoxin-induced uveitis. On days 1, 3, 7, 14, and 30 postoperatively the rabbits were sacrificed and the number of white blood cells in the aqueous humor and cellular deposits on the IOLs were estimated. On days 14 and 30 the rabbits also had slitlamp examination to study the clinical outcome of the surgery. At day 1 after lens extraction and IOL implantation, the number of white blood cells in the aqueous humor was significantly lower (P < .05) in eyes with heparin-surface-modified (HSM) IOLs (795.2 +/- 262.9; mean +/- SEM) than in eyes with poly(methyl methacrylate) (PMMA) lenses (1386.5 +/- 247.9). No differences were seen at day 3, 7, 14, or 30 postoperatively. The choice of IOL material had no effect on the amount of cell deposits on the IOL surface or on clinical parameters such as anterior synechias, posterior synechias, fibrosis, and posterior capsular opacification. There was a trend toward a greater number of cellular deposits on the PMMA lenses, but this was not statistically significant. This study provides further evidence of improved biocompatibility of the HSM PMMA lens, as demonstrated by a decreased acute inflammatory response.

Acute Disease↗

PubMed1992

Effects of Calaguala and an active principle, adenosine, on platelet activating factor.

Calaguala, an extract from the fern Polypodium decumanum, has been used to treat psoriasis and related immunological disorders. In an effort to explain Calaguala's medicinal effects the inhibitory activity of the extract in two platelet activating factor (PAF) related models has been investigated. In the first model, PAF was used to induce release of the proteolytic enzyme elastase in human neutrophils. Calaguala inhibited this effect with an IC50 of 0.1 mg/ml. The known PAF antagonist ginkgolide BN 52021 was used as a positive control and had an IC50 of 0.034 mg/ml. In the second model the inhibition of biosynthesis of PAF in neutrophils using lyso-PAF and labeled acetyl-CoA was studied. Also in this assay Calaguala showed a dose-dependent activity, the IC50 being 0.2 mg/ml. Since recent findings have indicated that PAF might be involved in the pathogenesis of psoriasis, it is possible that the activity shown by Calaguala in these PAF assays may contribute to the clinical efficacy of the extract. The PAF induced exocytosis assay was further used to guide the fractionation of the crude extract. From the acetone supernatant the nucleoside adenosine was isolated as an active principle. Pure adenosine dose-dependently inhibited the exocytosis induced by PAF (IC50 = 0.024 micrograms/ml) but was inactive in the biosynthesis assay. Adenosine is most probably one of the bioactive compounds of Calaguala responsible for its therapeutic properties.

Acetylation↗

PubMed1992

Topographic mapping of Helicobacter pylori colonization in long-term-infected pigs.

Four barrier-born pigs were inoculated with Helicobacter pylori during gastroscopy. Infection in all pigs was established after 3 weeks, and the animals were kept isolated from other pigs in ordinary experimental sites. The pigs were sacrificed and examined 3, 5, 6, and 6.5 months postinoculation. A detailed urease mapping of the pig stomachs showed a patchy distribution of H. pylori. The bacteria colonized in all pigs, with a concentration of H. pylori-positive areas in the antrum and fundus. Furthermore, the number of colonized areas tended to increase with time, and some of these areas showed a strong urease reaction, indicating a heavy colonization with H. pylori. Biopsies from these areas contained 10(2) to 10(5) CFU per 2-mm-wide biopsy. We conclude that persistence of H. pylori infection in barrier-born pigs can be demonstrated for at least 6.5 months. The patchy distribution and the variability of viable bacteria were similar to those described for humans.

Animals↗

PubMed1992

Secondary cataract. An in vivo model for studies on secondary cataract in rabbits.

Secondary cataract formation is the most common postoperative complication following cataract surgery. To study different methods preventing the secondary cataract formation a relevant animal model is required. An in vivo rabbit model for studies on the prevention of secondary cataract formation is presented. The lens nucleus and cortex were removed by phacoemulsification, and two months later the growth of the secondary cataract was estimated by scoring on a scale from 0-4, both central and peripheral, and by measuring the wet mass of the dissected secondary cataract. The model seems to be a relevant way to study different concepts for the prevention of secondary cataract formation.

Animals↗

PubMed1991

Methodological considerations when using nitrocellulose immunoblotting from polyacrylamide gels to study the mould allergens Aspergillus fumigatus and Alternaria alternata.

The effects of sample treatments, separation conditions, and the possible presence of antibody interference phenomena in sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS PAGE) followed by nitrocellulose immunoblotting (IB) were studied using allergens from Alternaria alternata (Alt.a.) and Aspergillus fumigatus (Asp.f.) as model systems. In order to obtain good resolution in the IB method the mould allergens were separated in gradient gels under dissociating conditions (SDSgPAGE) including sample treatment with boiling, SDS and 2-mercaptoethanol (ME). These treatments all reduced the IgE binding capacities of the Asp.f. and Alt.a. extracts studied. Nevertheless, a great variety of IgE-binding components were detected after IB, and this could probably be explained by refolding of allergens during the blotting procedure where SDS was partly removed. A comparison of IgG-enriched and IgG-reduced serum fractions in IB revealed small differences in the IgE-binding patterns suggesting that IgG interference is of minor importance in the system studied. The IB method must be individually optimized for each new allergen studied using well characterized sera, preferably monospecific for the major components. Taking these facts into consideration, the IB technique is a valuable complement to other methods in the study of mould allergens.

Allergens↗

PubMed1991

Purification of a 20 kD allergen from Aspergillus fumigatus.

Sera from patients sensitized to Aspergillus fumigatus (A.f.) were screened for specific IgE using sodiumdodecylsulphate-gradient-polyacrylamidegelelectrophoresis (SDSgPAGE) followed by immunoblotting to nitrocellulose. Approximately 25 IgE-binding components were detected. The components of molecular weight 20, 31, 44, 50, 53, 77 and 90 kD were reacting with more than 50% of the patients. The 90, 77 and 20-kD components showed up as the strongest IgE-binding bands. The 20-kD component, called Ag 20 kD, was purified and further characterized. Ag 20 kD was purified to apparent homogeneity. using a combination of size-exclusion chromatography on a Sephacryl S-200 column, preparative isoelectric focusing in a pI 2.5-6.5 gradient, and a Sephadex G-50 Superfine column. Fractions were characterized with protein and carbohydrate analyses, RAST and SDSgPAGE followed by immunoblotting to nitrocellulose. Ag 20 kD was found to be a glycoprotein as it stained with both Coomassie Brilliant Blue and PAS. However, it did not bind Con A, and thus, did probably not contain any terminal alpha-D mannopyranosyl end groups. The relation between mannose, galactose and glucose was found to be 2:1:0.5. The isoelectric point was heterogeneous within pH range 5-6, and the molecular weight was estimated to approximately 20 kD. An increased RAST response was shown for the purified component compared with crude extract using patient sera reacting with Ag 20. The antigen was shown not to be identical with the previously described Ag 3. Neither did it fit the description of Ag 5, 7 or 13 earlier described by the same group. The antigen is going to be used for further immunochemical and clinical investigations, and coupling to other systems for antigen characterization.

Allergens↗

PubMed1991

Studies of Helicobacter pylori in a gastric mucosa in vitro animal model.

A gastric mucosa in vitro model for studies of experimental Helicobacter pylori infections has been developed. Biopsy specimens were taken from pig gastric mucosa, infected with H. pylori, and cultured for up to 72 h. To determine the degree of H. pylori adhesion, specimens were vigorously rinsed by vortexing five times before measuring viable count and urease activity. The results showed that it is possible to culture pig gastric mucosa in vitro with maintained viability for at least 72 h. According to the viable count, the bacteria survived and multiplied during the whole culture period. The percentage viable H. pylori in the specimens after rinsing and the urease activity increased with time of culture. The results indicate that the bacteria in the gastric specimens were viable after 72 h and that there was a time-dependent increase in bacterial adhesion to the specimens. This in vitro gastric mucosa model promises to be an applicable and reproducible method, with high capacity, for both pathogenic and mechanistic studies of H. pylori infection.

Animals↗

PubMed1991

Adhesion of Helicobacter pylori to human gastric mucosal biopsy specimens cultivated in vitro.

The therapeutic advances in Helicobacter pylori infection is hampered by the lack of suitable animal model systems. We have previously reported on successful adherence of H. pylori to pig gastric mucosa cultured in vitro. The aim of this study was to verify the technique in human biopsy specimens cultured in vitro. Mucosal samples were taken from H. pylori-negative and H. pylori-positive patients undergoing gastric surgery. The non-infected tissue was infected with H. pylori in vitro, and the infected tissue was put into culture immediately. Total number and those H. pylori firmly attached were checked throughout a 72-h culture. Viability of cultured human gastric mucosa was good and unaffected by the presence of H. pylori. The amount of bacteria adhering, increased with time from 0.01% to 2-4% after 72 h in culture. In vivo-infected specimens initially had a low number of firmly attached H. pylori, but total H. pylori increased with time in culture. It is concluded that human gastric biopsy specimens show good viability for 72 h and that viability and cell division of H. pylori were maintained in both in vivo and in vitro H. pylori-infected tissue. In both cases the total number of viable bacteria attached to the specimens increased with incubation time.

Animals↗

PubMed1990

Detection of Chlorella-specific IgE in mould-sensitized children.

The content of IgE, specific to the unicellular green alga Chlorella sp., was analysed in sera from 46 atopic children sensitized to moulds, using radioallergosorbent test (RAST), immunoblotting and crossed immunoelectrophoresis/crossed radioimmunoelectrophoresis (CIE/CRIE). Chlorella-specific IgE was found in 23/46 sera by RAST, in 28/41 sera by immunoblotting and in 6/30 sera by CIE/CRIE. The Chlorella components most frequently binding IgE as analysed by gradient gel electrophoresis and immunoblotting were of molecular weights of approximately 13, 17, 19, 26 and 49 kD. Twenty-nine precipitating antigens, including seven IgE-binding precipitates were detected by CIE/CRIE. The study shows that low concentrations of specific IgE are formed to the green alga Chlorella in sera from atopic individuals sensitized to moulds.

Adolescent↗

PubMed1990

Preparation of allergen extracts from the green alga Chlorella. Studies of growth variation, batch variation, and partial purification.

Allergen extracts were prepared from different raw materials of three strains of the unicellular green alga Chlorella (C. vulgaris, C. homosphaera and C. saccharophila). Growth variation, batch variation and composition of partially purified extracts were studied by analyzing total protein and carbohydrate content, protein and IgE-binding patterns and allergenic potency. Chlorella allergens were produced in the same proportions in early and late exponential growth phases but appeared partly degraded in the stationary phase. Uniform growth and extraction from Chlorella cells in the late exponential phase were demonstrated. Partially purified extracts from cells in late exponential phase contained 50% protein of the dry weight compared to 20% in crude extracts. The carbohydrate content was 20-30% of the dry weight of both crude and purified extracts. The allergenic potency of the purified extracts was 150-340% of the crude extracts, as assayed by RAST inhibition. The purified C. vulgaris extract showed a reduced IgE binding compared to crude extracts, while C. homosphaera and C. saccharophila extracts exhibited consistent IgE binding and are therefore suitable for in vivo and in vitro studies of allergenic properties of Chlorella.

Allergens↗