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Biomedical subjects

L Andersson

Publications and source records attributed to L Andersson.

At least 343 records · Page 19Linked to original sources
PubMed1988

Dentoalveolar ankylosis and associated root resorption in replanted teeth. Experimental and clinical studies in monkeys and man.

Periodontal pathology is an unavoidable complication following replantation of avulsed teeth. The present thesis focuses on the etiology, diagnosis, progression and prevention of dentoalveolar ankylosis. The experimental studies were carried out both in vitro and in vivo. Clinical studies were also performed on the progression of ankylosis. Initially, it was determined that the histomorphometrical method used in the animal studies was sufficiently accurate for the estimation of an area of a root surface showing a defined condition. In vivo studies revealed that the periodontal membrane (PDM) of a tooth prevented from drying for one hour before replantation heals without root resorption and ankylosis in a similar manner to an immediately replanted tooth. However, replantation of a tooth with a necrotic PDM results in a rapid destruction of the root by inflammatory resorption. These observations were predicted from the results of the in vitro studies, indicating that data gained from in vitro work may contribute to our understanding of periodontal healing in replanted teeth. Prevention or elimination of inflammatory resorption results in increased dentoalveolar ankylosis. Masticatory stimulation during the healing period will maximize the area of functional PDM and minimize dentoalveolar ankylosis. Antibiotics should be administered as early as possible and endodontic treatment should be performed within the first weeks after replantation to prevent inflammatory resorption. Accurate diagnosis of dentoalveolar ankylosis by assessment of percussion sound and mobility is only possible when more than 20 percent of the root surface is ankylotic. Radiographic diagnosis of ankylosis is of limited value in the early stages of replacement resorption. The rate of replacement resorption was shown to be age related. Even though replacement resorption is present, a tooth in an older individual can remain functional for a long period, possibly throughout life. Furthermore, residual infection and associated periodontal inflammation may be moderating factors in the progression of replacement resorption.

Adolescent↗
PubMed1987

Interaction of proteins with immobilized Cu2+. Quantitation of adsorption capacity, adsorption isotherms and equilibrium constants by frontal analysis.

The interaction of lysozyme, ovalbumin, bovine and pig serum albumins with Cu2+ immobilized on Chelating Sepharose Fast Flow or TSK gel chelate-5PW was studied by frontal analysis at various initial concentrations of these solutes. The chromatographic data so obtained served as a basis for evaluating some relevant affinity chromatography parameters by adapting previously reported equations to this system. The TSK-based adsorbent had lower adsorption capacity for all the model proteins compared to the agarose-based adsorbent, due primarily to its lower porosity which has a marked influence on the accessibility of the immobilized ligand to the proteins. On the other hand, the TSK-based adsorbent offers almost ideal conditions for studying adsorption equilibria under column chromatographic conditions. The adsorption capacity of these adsorbents for the model proteins ranges from about 0.6 to 7 mumol/ml, equivalent to 40-100 mg/ml, of adsorbent. The following equilibrium constants for the interaction of the proteins with immobilized Cu2+ were obtained: lysozyme, 1.8.10(4); ovalbumin, 1.5.0(5); BSA, 1.7.10(5); PSA, 3.7.10(5) and imidazole, 8.10(3) M-1. Despite the comparatively low affinity of imidazole for the adsorbent, it is an effective competing ligand, at comparatively high concentrations, for adsorbed proteins primarily because all adsorption sites are available to it. The results obtained suggest that about 1/3 to 1/2 of the potential adsorption sites on the model proteins are involved in forming coordination complexes with Cu2+ immobilized to covalently bound iminodiacetate groups on insoluble gel matrices.

Adsorption↗
PubMed1987

High-performance analytical applications of immobilized metal ion affinity chromatography.

The separation of three sets of standard protein mixtures on a high-performance immobilized metal ion affinity chromatography (HP-IMAC) column by elution with linear gradients of imidazole is described. The affinity of the test proteins for the immobilized metal ions follows the order Cu2+ greater than Ni2+ greater than Zn2+. The iminodiacetic acid-Cu2+ column gives the best resolution of all three protein mixtures and is the only immobilized metal ion column that can be used for elution of absorbed proteins with a decreasing pH gradient. An application of HP-IMAC for the separation of monoclonal IgG from mouse ascites fluid is also outlined. This versatile separation method is thus suitable for both analytical and preparative separations of proteins and peptides resulting in high recoveries and good reproducibility. The leakage of immobilized metal ions from the TSK gel chelate-5PW is apparent if the column is eluted by buffers containing low concentrations of (i) glycine or (ii) primary amines at round neutral pH. Considerable amounts of immobilized Zn2+ and Ni2+ ions also leak from the column by washing with buffers of pH 4.5 or lower. However, all three immobilized metal ions are stable toward exposure to low concentrations of imidazole (up to 50 mM) in phosphate buffers between pH 6.5 and 8.0. Adsorbed proteins could thus be eluted conveniently by using linear gradients of imidazole to give reproducible results. Moreover, this elution procedure made it possible to use the IMAC columns for repeated runs without the need for regeneration and recharging of the columns with fresh metal ions after each use.

Antibodies, Monoclonal↗
PubMed1987

Facile resolution of alpha-fetoproteins and serum albumins by immobilized metal affinity chromatography.

We have explored immobilized metal affinity chromatography as a means of resolving alpha-fetoprotein from its homologous albumin, a problem perennially encountered in the purification of an alpha-fetoprotein or its detection. Human alpha-fetoprotein and human serum albumin were chromatographed on immobilized iminodiacetic acid charged with either Co2+, Ni2+, Cu2+, or Zn2+. Neither human alpha-fetoprotein nor human serum albumin displayed any affinity for Co2+ and Zn2+. However, both proteins were bound to Cu2+ and were partially resolved by affinity elution with imidazole. By contrast, human alpha-fetoprotein and human serum albumin were completely resolved on immobilized Ni2+. Similar results were obtained using bovine alpha-fetoprotein and bovine serum albumin. The resolution of an alpha-fetoprotein from serum albumin should aid the purification of alpha-fetoprotein from a biological fluid containing overwhelming quantities of albumin, for example, serum. Importantly, the separation of human alpha-fetoprotein from human serum albumin may improve and help maintain the accuracy of immunoassays for alpha-fetoprotein, making the chromatography on immobilized Ni2+ a valuable diagnostic tool.

Chromatography, Affinity↗
PubMed1987

Tracers for aerosol ventilation scintigraphy: Tc-99m versus In-113m.

113mIn has been proposed as a suitable tracer for aerosol ventilation scintigraphy in combination with 99mTc pulmonary perfusion scintigraphy. The high energy (393 keV) of 113mIn allows it to be detected in the presence of 99mTc, but degrades the spatial resolution which can be achieved. We have compared the resolution obtained with 99mTc and 113mIn in phantom experiments and in aerosol ventilation scans in 14 patients with airways disease. The resolution at the distances from the collimator encountered in lung scintigraphy was 10-20 mm for 99mTc and 15-40 mm for 113mIn. Aerosol ventilation images were abnormal in all patients. The 99mTc images showed peripheral defects and frequently central hot spots reflecting increased local aerosol deposition. In the 113mIn images, the lower resolution had a smoothing effect, the central hot spots were less striking, and the distribution of activity appeared more uniform, some detail was lost in the periphery. It is suggested that 113mIn is useful for ventilation scintigraphy in the diagnosis of pulmonary embolism, but that 99mTc is the tracer of choice if aerosol ventilation scintigraphy is used to study airways disease.

Female↗
PubMed1987

Analysis of class II genes of the chicken MHC (B) by use of human DNA probes.

Class II genes of the major histocompatibility complex (MHC) in the chicken have been investigated by Southern blot analysis using human cDNA probes for DQ alpha, DQ beta, DR alpha, and DR beta. Both beta probes but not the alpha probes cross-hybridized well with chicken DNA. The results indicated that the beta probes hybridized with at least two beta genes in the chicken MHC and there was no clear indication of a DQ-DR subdivision of chicken class II beta genes. The possibility of using human beta probes for MHC typing in the chicken was tested by using two homozygous individuals for each of 20 different, serologically defined, MHC (B) haplotypes originating from the domestic breeds of White Leghorn and Rhode Island Red, or from Red Jungle Fowl (the wild ancestral form). Genomic DNA samples from these individuals were digested with any one of the Eco RI and Pvu II restriction enzymes and hybridized with the DR beta probe. Restriction fragment length polymorphism (RFLP) was obtained with Pvu II only, which resolved seven different RFLP types. There was an excellent correlation between these RFLP types and the serological B typing since the RFLP type was identical within each pair of homozygotes. In addition to this broad survey of many haplotypes, a more detailed comparison was carried out on B21-like haplotypes originating from different breeds. No differences in restriction fragment patterns among these haplotypes could be resolved using any of the restriction enzymes Bg1 II, Eco RI, Hind III, Pst I, Pvu II, and Taq I.

Animals↗
PubMed1987

Serotonergic influence on the growth hormone response to clonidine in rat.

Administration of the alpha 2-adrenoceptor agonist clonidine induces growth hormone (GH) release in rat and man. In the present study it is shown that the GH response to clonidine is weaker in rats exposed to depletion of both noradrenaline and serotonin (by means of reserpine or the combined treatment of FLA-63 and PCPA) than in animals exposed to noradrenaline depletion (by means of FLA-63) only. The possibility that an impaired serotonergic neurotransmission contributes to the blunted GH responses to clonidine observed in patients suffering from endogenous depression is discussed.

Animals↗
PubMed1987

CT scan prior to installation of osseointegrated implants in the maxilla.

A method using computed tomography (CT) for evaluation of maxillary structures before installation of titanium fixtures is described. This method gives us comprehensive information of relevant bony structures and bone quality. The width of the paranasal sinuses, nasal cavity and incisal canal is properly evaluated and the method facilitates measurements of available space for position, number and length of fixtures to be installed.

Dental Implantation, Endosseous↗
PubMed1987

Cell cycle related [3H]thymidine uptake and its significance for the incorporation into DNA.

Cellular uptake of [3H]thymidine [( 3H]TdR) and incorporation into DNA of Ehrlich ascites tumour cells were studied in relation to the cell cycle by measuring the activity in the acid-soluble and insoluble parts of the cell material. Cells were synchronized at various stages of the cell cycle using centrifugal elutriation. The degree of synchrony of the various cell fractions was measured by flow-cytofluorometric DNA analysis. From the cellular uptake, the TdR triphosphate (dTTP) concentration of a mean cell in an unseparated cell population was calculated to be 20 X 10(-18) mol/cell. The pool activity of G1 cells was unmeasurable but rose to maximum values at the border of the G1-S phase. It decreased again during G2. The [3H]TdR incorporation into DNA was low during early S phase, reached a maximum value at two-thirds of the S phase and decreased again during late S phase. These changes in DNA synthesis were not due to changes in the dTTP pool being a limiting factor. During maximum DNA synthesis, 10% X min-1 of the dTTP pool was utilized, at which time the pool size also decreased by about 30%. Changes in pool size during the cell cycle have to be taken into account when the results of incorporation of radioactive TdR into DNA are discussed.

Animals↗
PubMed1987

Mortality and cancer incidence among workers in an abrasive manufacturing industry.

Earlier epidemiological studies have shown that exposure to aluminium oxide and silicon carbide might carry with it an increased risk of lymphomas, stomach cancer, and non-malignant respiratory disease. To elucidate further this possible hazard, the cancer morbidity and the total mortality pattern was studied among 521 men manufacturing abrasive materials who had been exposed to aluminium oxide, silicon carbide, and formaldehyde. Total dust levels were in the range of 0.1-1.0 mg/m3. The cohort was followed up from 1958 until December 1983. No significant increase was found in total mortality, cancer mortality, or incidence of non-malignant respiratory diseases.

Aluminum Oxide↗
PubMed1987

Metabolism of [14C] felodipine, a new vasodilating drug, in healthy volunteers.

After oral administration of [14C] felodipine (27.5mg) to 4 healthy volunteers, 6 main urinary metabolites were identified by gas chromatography-mass spectrometry. The compounds were isolated by solvent extraction at pH 2.2 and silylated prior to analysis. They were formed by dehydrogenation of felodipine followed by ester hydrolysis, hydroxylation of the alkyl groups and conjugation. These metabolites were excreted both as free acids and as conjugates accounting on average for 37% of the excreted amount (23% of the dose). A specific liquid chromatographic assay with radioactive detection was developed to determine the acidic metabolites in all collected samples. The urinary excretion rate declined biphasically for the mono-acids III and IV, whereas the excretion rates of metabolites VI, VII and VIII, formed via aliphatic hydroxylation, were better fitted to equations of first-order processes.

Biotransformation↗