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Biomedical subjects

B Nilsson

Publications and source records attributed to B Nilsson.

At least 469 records · Page 26Linked to original sources
PubMed1987

Cryopreservation of mouse pancreatic islets: effects of human serum on islet survival.

The aim of this study was to compare the survival of cryopreserved mouse pancreatic islets frozen in the presence of either a simple salt solution (Hanks' balanced salt solution) or a complete tissue culture medium (RPMI 1640). Moreover, the addition of 10% human serum to the freezing solutions was evaluated. Collagenase isolated islets were kept in culture for three days, before being cooled at a rate of 5 degrees C/min or 25 degrees C/min to -70 degrees C, at which temperature the islets were transferred to liquid nitrogen. All freezing media were supplemented with 2 M dimethylsulphoxide as cryoprotectant. The islets were rapidly thawed at 37 degrees C and subsequently cultured for another three days. The recovery of islets was higher when the more rapid cooling rate was used and the addition of serum further improved the recovery. Compared to non-frozen cultured islets there was a loss of cells in all groups of cryopreserved islets, as measured by their DNA content, and this was accompanied by a lowered insulin content. All groups of frozen-thawed islets responded to a high glucose stimulus in vitro with a 5-9 fold increase in insulin secretion. There was no obvious advantage of using a complete tissue culture medium for islet cryopreservation, but the addition of serum had some beneficial effects. Data obtained from non-frozen control islets suggest that human serum slightly impairs the function of mouse pancreatic B-cells.

Animals↗
PubMed1987

S-phase lymphocytes in chronic lymphocytic leukemia (CLL) in relation to immunoglobulin isotypes on the leukemic clone and to disease activity.

The fraction of blood S-phase (S+) lymphocytes from 41 patients with chronic lymphocytic leukemia of B cell type was determined by flow cytometry. The patients were grouped according to the smig isotype pattern of the leukemic cells. Patients with IgM as the predominant smig had higher numbers of S+ lymphocytes than patients with a leukemic clone co-expressing IgM and IgD (p less than 0.001). High relative as well as total numbers of S+ lymphocytes were associated with short therapy-free and overall survival. T cell proliferation was low although significantly higher in active than in indolent disease.

B-Lymphocytes↗
PubMed1987

Operative versus non-operative treatment of recent injuries to the ligaments of the knee. A prospective randomized study.

Two hundred consecutively seen patients who had an injury to either the anterior cruciate ligament or the medial collateral ligament, or both, were randomly allocated to treatment by either conservative or a surgical regimen. Injuries to the medial collateral ligament could not be demonstrated to benefit from surgical treatment in any respect--with or without surgery the results were excellent. With injuries to the anterior cruciate ligament, recovery was more rapid without surgery but otherwise the results differed between the groups in only one respect: the pivot-shift test was more often positive after conservative treatment. The results were good in both treatment groups even though most of the patients who had an injury of the anterior cruciate ligament were somewhat less pleased with the outcome after a period of time.

Adolescent↗
PubMed1987

Immunological recovery after bone marrow transplantation: role of age, graft-versus-host disease, prednisolone treatment and infections.

Cellular immune recovery was studied in 67 patients who had survived for one month to more than 6 years after bone marrow transplantation (BMT). From a number of immunological parameters the mitogens phytohemagglutinin, concanavalin A and rabbit antibodies to beta 2 microglobulin (A-beta 2m) were chosen because of relevant increases in lymphocyte responses with time after BMT for analysis with exponential functions (covariance analysis). Patients with younger donors had a markedly higher lymphocyte response level and a faster rate of increase with time than patients with older donors. High recipient age was also significantly associated with a depressed level of immunological response but to a lesser degree than donor age. Patients with chronic graft-versus-host disease (GVHD) had a more severely impaired response compared to patients without chronic GVHD. Furthermore, patients with GVHD showed a negative development over time with the A-beta 2m test. Lymphocytes from patients receiving a low donor marrow cell dose showed impaired response levels and rate of recovery compared to the high-dose group although the differences were not significant. Patients treated with prednisolone for grade I GVHD had depressed lymphocyte stimulations for up to 1 1/2 years post BMT compared to patients without GVHD and not receiving prednisolone. Patients with non-viral infections seemed to have more depressed lymphocyte responses than non-infected patients. Patients undergoing cytomegalovirus infections had lower response levels for all three mitogens.

Adolescent↗
PubMed1987

A retrospective study on the relevance of the dental curriculum in general practice.

The undergraduate dental curriculum in Swedish dental schools has recently been changed. The aim of this study was to estimate the opinions of recently qualified dentists concerning their undergraduate education received according to the old curriculum. A questionnaire was mailed to all graduates who qualified from the dental school in Huddinge between 1981-1983. The response rate was 71%. The respondents indicated that their theoretical knowledge was in general better in subjects closely related to clinical dentistry compared with basic biological subjects or behavioural science subjects. In most subjects clinical competence was closely related to the level of theoretical knowledge. The results of this study suggest that the "old" dental curriculum was successful in imparting knowledge concerning traditional dental subjects and preventive dentistry, but less successful in imparting knowledge concerning basic and medical sciences, behavioural subjects and in relating theoretical and practical skills.

Adult↗
PubMed1986

Heparin-induced osteoporosis in rats.

In order to study the effect of heparin in inducing osteoporosis, 30 female rats were divided in two groups and treated with daily injections of 2 IU heparin/g body weight for 33 and 65 days and compared with the same number of rats acting as controls. The mineral bone mass in the femora of the animals was measured quantitatively. A significant (p less than 0.001) reduction in bone mineral mass was found in the heparin-treated animals. This effect was present to the same degree after 33 days as after 65 days of treatment. It is concluded that heparin in this dose causes osteoporosis in rats after 33 days and that the described method can be used as an experimental model for further studies on this topic.

Animals↗
PubMed1986

Secretion of heterologous gene products to the culture medium of Escherichia coli.

Different constructs containing fragments of the Staphylococcal protein A gene have been introduced in Escherichia coli and the effect on expression and translocation of the various heterologous gene products have been studied. By reversing the orientation of the different protein A gene constructions in the plasmid vector, a dramatic 20-fold difference in expression was obtained, accompanied with secretion of the gene product to the culture medium. Similar results were obtained by "heat-shock" treatment of the E.coli host cells. These results suggest the presence in the protein A gene of a stress induced promoter, functional in E.coli. The system was used to efficiently secrete a fusion protein consisting of a protein A fragment and human insulin-like growth factor I (IGF-I) to the culture medium of E.coli HB101. The fusion protein was purified from the culture medium by IgG affinity chromatography in a one-step procedure giving more than 95% yield.

Culture Media↗
PubMed1986

Staphylococcal protein A consists of five IgG-binding domains.

A genetic approach is described to clarify the IgG-binding properties of the N-terminal portion of staphylococcal protein A (region E). Several gene fragments, encoding region E or B or protein A, have been cloned and expressed in Escherichia coli. The gene products were purified by IgG-affinity chromatography and subjected to structural and functional analyses. Both fragments can be efficiently purified using this method, suggesting that region B as well as region E has Fc-binding activity. In addition, gene fusions were assembled giving fragments EB and EE, which both showed a divalent Fc-binding. These results demonstrate that protein A consists of five IgG-binding domains. The implications of these findings for the structure of protein-A--immunoglobulin-G complexes are discussed.

Amino Acids↗
PubMed1986

Production of specific antibodies against protein A fusion proteins.

The gene for Staphylococcal protein A was fused to the coding sequence of bacterial beta-galactosidase, alkaline phosphatase and human insulin-like growth factor I (IGF-I). The fusion proteins, expressed in bacteria, were purified by affinity chromatography on IgG-Sepharose and antibodies were raised in rabbits. All three fusion proteins elicited specific antibodies against both the inserted protein sequences and the protein A moiety. In the case of IGF-I, the protein A moiety in the fusion protein may act as an adjuvant since native IGF-I alone is a poor immunogen. The results suggest that the protein A fusion system can be used for efficient antibody production against peptides or proteins expressed from cloned or synthetic genes. To facilitate such gene fusions a set of optimized vectors have been constructed.

Alkaline Phosphatase↗
PubMed1986

Blood pressure regulation in third-trimester pregnant women receiving tocolytic terbutaline infusion.

Terbutaline (20 micrograms/min) was infused during 30 min in 17 women in whom a manual external manipulation of a breech presentation was going to be attempted. A significant increase in systolic (P = 0.003) and a decrease in diastolic blood pressure (P = 0.04) was noted at the end of the infusion but no change in mean arterial blood pressure was obtained. At the same time aldosterone serum levels had dropped significantly (P = 0.009) and plasma angiotensin II showed a marked increase (P less than 0.001) which continued during the next 30 min. All changes were normalized after the infusion. The angiotensin-converting enzyme activity remained unchanged, as did vasopressin plasma levels. The combined results of terbutaline provocation have been interpreted to mean that blood pressure regulation in third-trimester pregnant women is similar to that in nonpregnant individuals. The increase in dehydroepiandrosterone sulphate (P less than 0.05) noted at the end of infusion was suggested to be related to the blood pressure changes and was unrelated to fluctuations in serum cortisol. The latter steroid increased between 30 and 60 min, e.g. during the manual external manipulation, and was interpreted as being due to maternal stress.

Adult↗
PubMed1986

SDS denaturation of complement factor C3 as a model for allosteric modifications occurring during C3b binding: demonstration of a profound conformational change by means of circular dichroism and quantitative immunoprecipitation.

The antigenic expression of bound but not fluid-phase C3b closely resembles that of sodium dodecyl sulphate (SDS) denatured C3. For this reason, denatured C3 has been used in this study as a model to characterize the conformational changes associated with bound C3b. It was shown in circular dichroism in the far UV spectrum that profound changes in the secondary structure occurred in denatured C3. Furthermore, quantitation by immunoprecipitation of the previously observed antigenic changes during denaturation demonstrated that C3 lost 2/3 of the antigens associated with native C3 whereas 1/3 were stable. The lost antigens were completely replaced by antigens that are specific for denatured and bound C3. We postulate that the binding of C3b is accompanied by a profound conformational change distinctive of that observed in fluid-phase C3b.

Allosteric Site↗
PubMed1986

Ultraviolet radiation and air contamination during total hip replacement.

Ultraviolet (uv) radiation of the operating room was assessed bacteriologically in an open randomized study of 30 total hip procedures. Volumetric air-sampling demonstrated that the number of colony forming units (cfu m-3) were significantly reduced (P less than 0.001) by uv light, both close to the wound and in the periphery of the operating room. No adverse effects of the uv-irradiation were observed either in the patients or the staff. In operating rooms fitted with a 'zonal ventilation' system and with an air change rate of about 70 h-1, the addition of uv irradiation during surgery may achieve 'ultra clean' air. However, in conventionally ventilated operating rooms uv-irradiation alone is probably not sufficient to do so.

Air Microbiology↗
PubMed1986

Electron contamination from photon beam collimators.

Photon beam collimators are a source of secondary electrons that contaminate the beams and increase the surface dose. Calculations and measurements of this contamination have been made for 6 MV and 21 MV X-ray beams. Calculations are made using an electron transport model including the production of electrons by the photons and their transport and multiple scatter, both in the collimator and in the air. The variation with collimator material and geometry is investigated. The lowest contamination is obtained for high density and atomic numbers because of the small lateral electron range and large linear stopping power. The collimator geometry is also very important. If the collimator surfaces are hit by the photons, the collimator-produced electrons reaching the phantom may be increased by a factor of 2 or more. Calculations show that the surface dose from these electrons is less than 5% for 21 MV X-rays. This means that the dominating source of contaminating electrons at this energy is the beam flattening filter.

Electrons↗
PubMed1986

Antigens of complement factor C3 involved in the interactions with factors I and H.

This study explores the relationship between defined antigens of the C3 molecule and those surface structures that are involved in interaction with factors I and H. Methylamine treatment at pH 11 followed by neutralization converts C3 into a modified state in which the molecule is optimally susceptible to cleavage by factor I in the presence of factor H. The modified C3 is characterized by an antigenic profile with expression of antigens of the C3(N), C3(S), and C3(D) subsets. These antigenic properties closely mirror those of physiologically bound C3b, suggesting that modification of antigenic expression upon denaturation of C3 reflects a regulatory mechanism for I and H function. Immunochemical studies of the alkaline-denatured C3 suggested that factor H interacts with surfaces of C3 that are situated within the C3c fragment and that are defined by C3(SN) antigens, while factor I predominantly interacts with C3(SN) antigens associated with the C3d fragment and with C3(D) antigens hidden in native C3. Therefore the continuing immunochemical study of this and related problems will require polyclonal and monoclonal antibody reagents reactive not only with the C3(S) and C3(N) but also the C3(D) antigenic subsets.

Antibodies↗
PubMed1986

Defective recloning capacity of granulocyte-macrophage colony-forming cells in chronic myeloid leukaemia.

We investigated the recloning capacity of normal and chronic myeloid leukaemia granulocyte-macrophage colony-forming cells (CFU-GM) after 7 d culture in methylcellulose. Normal CFU-GM were recloned with the formation of 3.52 +/- 1.12 secondary CFU-GM per primary d-7 colony. A frequency distribution of the colony-forming cells within d-7 colonies showed a heterogeneous distribution with the majority of d-7 colonies containing 1 or zero CFU-GM and a few colonies containing more than 30 CFU-GM. Separation of marrow cells by velocity sedimentation demonstrated that the recloning capacity was primarily expressed by the smallest colony-forming cells. In contrast, marrow or blood cells from 18 patients with Ph1-chromosome-positive CML in the chronic phase produced colonies with defective recloning capacity. Only 1 patient had a recloning value within the normal range; the others had a mean value of 0.35 (range 0-1.28) secondary colonies per primary d-7 colony. The recloning defect was not related to WBC or treatment, since 5 newly diagnosed patients with CML also showed defective recloning before any treatment was given, which is compatible with the defect being an inherent property of CML.

Bone Marrow↗
PubMed1986

Influence of blood group on the availability of receptors for attachment of uropathogenic Escherichia coli.

Escherichia coli strains with defined receptor specificity were used as probes to analyze the individual variation in host cell receptors with respect to blood groups. The adhesins were initially characterized as mannose sensitive (MS), mannose resistant (MR), or nonagglutinating (-). The receptor specificity of the strains with MR adhesins was defined by agglutination of synthetic Gal alpha 1----4Gal beta covalently linked via a spacer arm, (CH2)2S(CH2)2CO approximately H-bovine serum albumin (BSA) to BSA-latex beads as specific for the globoseries glycolipid receptors (MR:GS). Strains with MR adhesins not reacting with Gal alpha 1----4Gal beta-BSA-latex were designated MR:nonGS. The attachment and hemagglutination of the MR:GS strains was strictly dependent on Gal alpha 1----4Gal beta-containing receptors, as shown by the absence of binding to cells from individuals of blood group P lacking these structures. Previous reports showed differences in the composition of globoseries glycolipids between erythrocytes from individuals of P1 and P2. No significant difference was found, However, in the mean adhesion to P1 and P2 epithelial cells or in the agglutination titer for P1 and P2 erythrocytes. The MR:GS receptors were equally distributed on squamous and transitional epithelial cells. In contrast, the distribution of MR:nonGS receptors was skewed. Attachment occurred mostly to squamous epithelial cells. The attachment of strains with MR:nonGS adhesins was independent of the P blood group of the cell donor. The binding ability of MR:GS and MR:nonGS adhesins appeared independent and additive. The attachment was not influenced by the ABH blood group. However, increased binding to epithelial cells from nonsecretors occurred regardless of the P blood group, suggesting a shielding of receptors by products controlled by the secretor genes. These results illustrate how individual variation in cell surface components with and without receptor activity determine the interaction of a ligand with a known receptor.

Adhesins, Escherichia coli↗
PubMed1986

Identification of a nonproteolytically activated C3 with CR 1-binding properties in sera from subjects with primary biliary cirrhosis.

Complement factor C3 associated with immune complex-like material was precipitated by 2.7% (w/v) polyethylene glycol (PEG) in sera from patients with primary biliary cirrhosis. Radioimmunoassay analysis demonstrated that this C3 expressed antigens which are specific for bound and denatured C3 but absent in native C3. Gelfiltration of the PEG precipitate revealed a C3 peak which corresponded to a molecular weight of more than 2 X 10(7) daltons but sucrose-gradient centrifugation of the same material showed that the C3 had a sedimentation coefficient of 4-7 S. SDS-PAGE followed by immunoblotting presented intact C3 alpha and C3 beta chains, and immune electrophoresis showed that the PEG-precipitated C3 was slower than native C3. The biological properties of the PEG-precipitable C3 were demonstrated by the inhibitory effect on the binding of immune complexes containing C3b to complement receptor 1. These data are not compatible with coprecipitation of native C3, nor with immune complex-bound C3b.

Antigen-Antibody Complex↗