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Biomedical subjects

A Henriksen

Publications and source records attributed to A Henriksen.

28 records · Page 2Linked to original sources
PubMed1993

Pancreatic spasmolytic polypeptide: first three-dimensional structure of a member of the mammalian trefoil family of peptides.

BACKGROUND: The trefoil peptides are a rapidly growing family of peptides, mainly found in the gastrointestinal tract. There is circumstantial evidence that they stabilize the mucus layer, and may affect the rate of healing of the mucosal epithelium. RESULTS: We have determined the structure of porcine pancreatic spasmolytic polypeptide (PSP) to 2.5 A resolution. The polypeptide contains two trefoil domains. The domain structure is compact, and is composed of a central short antiparallel beta-sheet with one short helix above and one below it. This is a novel motif. The two domains are related by two-fold symmetry, and each domain contains a cleft. CONCLUSIONS: The cleft within each domain could accommodate a polysaccharide chain, and may therefore be responsible for binding mucin glycoproteins. We suggest that PSP may cross-link glycoproteins, explaining its ability to stabilize the mucus layer.

Amino Acid Sequence↗
PubMed1992

Crystallization and preliminary X-ray diffraction studies of a peroxidase from barley grain.

Crystals suitable for X-ray diffraction analysis of both glycosylated and non-glycosylated forms of a barley peroxidase have been grown. The crystals of the glycosylated peroxidase have been grown by the hanging drop vapour diffusion method using polyethylene glycol 4000 as the precipitant in the presence of n-propanol and potassium iodide at pH 8.5. The crystals are needles belonging to the orthorhombic spacegroup P2(1)2(1)2(1) with unit cell dimensions a = 62.95 A, b = 66.24 A and c = 70.78 A. There is one barley peroxidase molecule in the asymmetric unit. The crystals contain approximately 38% solvent and appear to be stable to lengthy X-ray exposure. They diffract to beyond 1.9 A.

Crystallization↗
PubMed1982

Monoclonal human B lymphoma cells respond to DNA synthesis to anti-immunoglobulins in the presence of the tumour promotor TPA.

Monoclonal human B lymphoma cells were triggered in vitro to DNA synthesis with F(ab')2 fragments of rabbit IgG antibodies specific for different human immunoglobulin (Ig) light and heavy chains. The specificity of the responses corresponded to surface Ig (sIg) present on tumour cells. Anti-mu chain, anti-delta chain, and antibodies to light chains were found to mediate this effect. However, to induce DNA synthesis, the tumour promotor 12-O-tetradecanoyl-phorbol-13-acetate (TPA) was usually required. TPA alone induced cytoplasmic protrusions and increases in cellular volume. These observations should provide new opportunities to study the triggering of B cells with anti-Ig in well-defined cell populations.

Antibodies, Anti-Idiotypic↗
PubMed1980

Mitogenic effect on human lymphocytes of insolubilized anti-immunoglobulins. I. Specificity of the stimulating agent.

The mitogenic response of peripheral blood lymphocytes to various anti-immunoglobulin reagents has been studied by measuring incorporation of a radioactive thymidine into macromolecules. Coupling of anti-F(ab')2 or anti-light chain antibodies to Sepharose beads leads to a 5-fold increase in their mitogenic capacity with 50-fold less antibodies per culture. Pepsin-digested F(ab')2 fragments had a mitogenic capacity similar to intact antibody molecules. Anti-F(ab')2 antibodies purified by immunoabsorbent columns were found to be more effective as mitogen than unpurified antibody fractions. Antibodies to kappa- or lambda-light chains were found to be mitogenic, whereas antibodies specific to various heavy chain classes failed to induce a significant response. Isolated light chains were much more effective in inhibiting the reaction than isolated mu-chains. It is concluded that insolubilized anti-light chain antibodies are mitogenic to human peripheral blood lymphocytes.

Animals↗
PubMed1978

Altered membrane-associated functions in chronic lymphocytic leukemia cells.

Peripheral blood lymphocytes consisting mainly of neoplastic B cells from patients with chronic lymphocytic leukemia (CLL cells) showed a markedly reduced response to the human B-cell mitogens anti-beta2 microglobulin, Sepharose-bound protein A and Sepharose-bound anti-human immunoglobulin (anti F(ab')2) in all of nine patients studied. On the other hand, CLL cells from three out of eight patients tested responded well to the calcium ionophore A23187. Sepharose-bound protein A and anti-beta2 microglobulin also failed to induce increased uptake of 86Rubidium (potassium analogue) in CLL cells as compared to B-cell-enriched preparations of normal peripheral blood lymphocytes. The capacity of CLL cells to cap various surface markers including beta2 microglobulin was reduced. On the other hand, surface concentrations of beta2 microglobulin were not reduced as measured by fluorescein-labelled anti-beta2-microglobulin in single-cell cytofluorometry. It is concluded that various membrane-associated events elicited by ligand-receptor interactions are altered or blocked in CLL cells.

Aged↗
PubMed1976

On the significance of the carbohydrate moieties of bovine prothrombin for clotting activity.

Purified bovine prothrombin has been treated with different mixtures of glycosidases. Upon incubation of the prothrombin for 30 h with a combination of neuraminidase, alpha- and beta-galactosidase and beta-N-acetylglucosaminidase in 4 mM diisopropylfluorophosphate at pH 5.3 and 30 degrees C, about 70% of the carbohydrates were removed without affecting the coagulation activity. All the sialic acid and about half of the mannose, galactose and glucosamine residues were removed by this treatment.

Acetylglucosamine↗
PubMedDate not supplied

Effects of regional reductions in sulphur deposition on the chemical and biological recovery of lakes within Killarney Park, Ontario, Canada.

The lakes in Killarney Provincial Park, located 40-60 km southwest of Sudbury, Ontario, were some of the first lakes in North America to be acidified by atmospheric pollutants. Acidification affected thousands of fish and invertebrate populations in dozens of lakes. Since the 1970's, water quality has improved in response to atmospheric pollution reductions and some lakes have already recovered to approximately their pre-industrial pH levels, as inferred from diatom microfossils in lake sediments. Since the 1970's, fish species richness has not changed substantially, but zooplankton species richness has increased in acidified lakes. The critical sulphur load, the amount of SO2-derived acid deposition that can occur while still maintaining suitable water quality, was estimated to be exceeded in 38% of the park area in 1997. Depending on which of four possible North American emission control scenarios (CLR = currently legislated reduction; CLR + 25%; CLR + 50%; CLR + 75%) is achieved by 2010, the projected critical loads will be exceeded in about 0-30% of the park area in the future. There are many factors that can affect biological recovery rates of damaged lakes, but it is expected that biological recovery will lag considerably behind observed chemical recovery rates.

Acid Rain↗