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Biomedical subjects

A Hedin

Publications and source records attributed to A Hedin.

At least 37 records · Page 2Linked to original sources
PubMed1988

In vitro studies of the biological effects of cigarette smoke condensate. III. Induction of SCE by some phenolic and related constituents derived from cigarette smoke. A study of structure-activity relationships.

Since our earlier studies of 23 individual weakly acidic constituents of cigarette smoke indicated that benzenes having vicinal oxygenation or a conjugated double bond induce sister-chromatid exchanges (SCE), we have now selected and examined a complementary set of 27 smoke constituents for their SCE-inducing properties. Of the 50 compounds tested in all, 23 were found to induce SCE, and these include all benzaldehydes but one and the majority of the compounds having a conjugated carbon-carbon double bond as well as several of the guaiacols. These groups of active compounds comprise important flavourants such as vanillin, ethylvanillin, isoeugenol and guaiacol. The structure-activity relationships encountered here may be useful in predicting the SCE-inducing activity of related compounds.

Benzaldehydes↗
PubMed1988

Eyelid surgery in dysthyroid ophthalmopathy.

Dysthyroid ophthalmopathy often gives rise to functional and cosmetic problems due to eyelid retraction. There are several causes of this state which are usually most obvious in the upper lid. Surgery should be delayed until the condition is stable and other operations have been done. A number of operative procedures have been used. In the upper eyelid, the traction of the Müller muscle and, most often, the levator is released; in the lower eyelid, the retractors are recessed or excised. Spacers have been used especially in the lower lid. The retractors can be reached either through the skin or the conjunctiva. Both methods give good results. In the upper lid, the risk of damaging other structures is lower with a skin incision; in the lower lid the conjunctival incision gives easier access to the tissues. The complications most frequently seen are over- or undercorrection both of which may necessitate a reoperation.

Autoimmune Diseases↗
PubMed1987

An experimental model for pharmacokinetic studies of monoclonal antibodies in human colonic cancer.

An experimental model consisting of athymic rats carrying human colonic tumours from cell line LS 174T in both hind legs was used. 125I-labelled anti-carcinoembryonic antigen (anti-CEA) monoclonal antibodies were injected intra-arterially (i.a.), either alone (21 rats) or together with degradable starch microspheres (6 rats). As a control, an irrelevant antibody was injected i.a., alone (6 rats) or together with microspheres (3 rats). An intra-arterial injection was given on the side bearing one tumour in each rat, while the contralateral tumour served as an 'intravenous' control. The rats were submitted to external gamma measurements daily for four days. On the fourth day they were killed and pieces from the tumours and from various organs were examined by in vitro measurements. The results indicate strong expression of CEA in LS 174T cells grafted to athymic rats. No lasting enhancement of the tumour uptake was achieved by intra-arterial injection of antibodies as compared with the control tumours.

Animals↗
PubMed1987

Enhanced uptake of intra-arterially injected anti-CEA monoclonal antibodies in human colonic cancer after mannitol infusion in an experimental model.

In a previous report athymic rats carrying transplanted human colonic tumours from cell line LS 174T in both hind legs were injected intra-arterially (i.a.) with 125I-labelled anti-carcinoembryonic (anti-CEA) monoclonal antibodies. The i.a. injection was given on one side bearing a tumour in each rat, while the contralateral tumour served as an 'intravenous' control. In the same experimental model and treated in the same way, 10 rats were injected i.a. with anti-CEA monoclonal antibodies after an i.a. mannitol infusion. In both groups of rats external gamma measurements were performed daily for four days. On the fourth day the rats were killed and pieces of the tumours and of various organs were weighed and the activity was determined with a gamma-counter. The tumour uptake of antibodies was significantly enhanced after mannitol infusion.

Animals↗
PubMed1986

Epitope specificity and cross-reactivity pattern of a large series of monoclonal antibodies to carcinoembryonic antigen.

Monoclonal antibodies (MAbs) were produced against purified carcinoembryonic antigen (CEA) from liver metastases of colo-rectal and lung adenocarcinoma. Three and eight anti-CEA MAbs from the two groups were analyzed in detail. All antibodies were IgG1. With one exception they recognized epitopes present on all eight individual CEA preparations investigated irrespective of whether they were from colo-rectal or lung carcinoma. The exceptional MAb reacted with an epitope present on most but not all CEA preparations. With two, or possibly three, exceptions the MAbs recognized conformation dependent epitopes in the peptide moiety of CEA. One MAb reacted strongly with reduced and carboxymethylated CEA but only weakly with native CEA. Four MAbs appeared to be CEA-specific in that they did not react with any of the known CEA-cross-reactive substances including nonspecific cross-reactive antigen of 160,000 mol. wt (NCA-160). A total of nine different epitopes were detected in native CEA using this and our previous series [Hedin A., Hammarström S. and Larsson A. (1982) Molec. Immun. 19, 1641] of anti-CEA MAbs. With one exception practically all molecules (70-90%) in purified CEA preparations contained these epitopes.

Antibodies, Monoclonal↗
PubMed1986

In vitro studies of biological effects of cigarette smoke condensate. II. Induction of sister-chromatid exchanges in human lymphocytes by weakly acidic, semivolatile constituents.

Cigarette smoke condensate is known to enhance the frequency of sister-chromatid exchanges (SCE) in human lymphocytes in vitro and some of the activity has been found in the most volatile part of the particulate phase, the semivolatile fraction. In this study we have investigated the chemical composition and the SCE-inducing activity of the weakly acidic, semivolatile fraction of a cigarette smoke condensate. A number of individual weakly acidic compounds were also tested for their SCE-inducing effects. The weakly acidic fraction was separated by preparative gel chromatography into 11 subfractions (F1-F11). The chemical composition was determined by gas chromatography and gas chromatography-mass spectrometry. Measurements of the effects on SCE in human lymphocytes were used to evaluate the genotoxic effects. All fractions except F11 induced SCE in a dose-dependent way. The most active fraction was F4 which contained mainly alkyl-2-hydroxy-2-cyclopenten-1-ones. The individual compounds to be tested for induction of SCE were selected on the basis of their abundance in the weakly acidic subfractions and on the basis of their occurrence in the environment. Of 23 tested compounds, most of which were alkylphenols, 7 induced SCE, i.e., catechol, 2-(1-propenyl)phenol, cyclotene, maltol, isoeugenol, 2-methoxyphenol (guaiacol) and vanillin. Many of these are important flavor components that occur not only in tobacco and tobacco smoke but also in food, candies, beverages and perfumes.

Acids↗
PubMed1985

Purification of in vitro produced mouse monoclonal antibodies. A two-step procedure utilizing cation exchange chromatography and gel filtration.

A method for production of purified and concentrated mouse monoclonal antibodies was developed. The rationale for the procedure is, firstly, to expand hybridoma cell number in culture medium-containing serum; secondly, to transfer the cells to serum-free medium for production of antibodies; and finally, to harvest antibodies from the conditioned medium by means of cation exchange chromatography on SP-Sephadex C-50, followed by gel filtration on Superose 6B. When compared with chromatography of monoclonal antibodies on protein A-Sepharose our results suggest that the method is particularly useful for purification of antibodies of the IgG1 subclass. Experience from production and purification of 15 various monoclonal antibodies is reported.

Animals↗
PubMed1985

The Boström-Kugelberg pseudo-isochromatic plates. How efficient is the third edition?

The third edition of the Boström-Kugelberg pseudo-isochromatic plates was printed to the best possible visual match with the second edition. Slight colour differences between the 2 editions initiated this study where 72 colour defectives and 57 normal trichromats were tested with the plates and classified with the aid of Nagel's anomaloscope. Of the defectives, the plate test disclosed all but two anomalous trichromats. One normal subject was falsely classified as defective. The plates had to be shown twice according to the instructions since otherwise 13 of the 53 normals were misclassified. Three plates were shown to have low sensitivity; one is best used as a demonstration plate, and the other two can be deleted without lost efficiency. Forty-eight of the colour defectives were also studied with Farnsworth's lantern. The correlation between the numbers of plate and signal errors was weak. All subjects who failed the lantern test made several plate errors, but 15 subjects who passed the lantern test, made two or more errors on the plate test. The outcome of the plate test does not give evidence of the subject's lantern test performance.

Adolescent↗
PubMed1984

Molecular weight determinations of proteins by californium plasma desorption mass spectrometry.

The plasma desorption mass spectrometry method is used to determine the molecular weights of larger molecules than before, to determine the molecular weights of proteins and peptides in mixtures, and to monitor protein modification reactions. Proteins up to molecular weight 25,000 can now be studied with a mass spectrometric technique. Protein-peptide mixtures that could not be resolved with conventional techniques were successfully analyzed by this technique. The precision of the method is good enough to permit one to follow the different steps in the conversion of porcine insulin to human insulin.

Animals↗
PubMed1984

Letter legibility and the construction of a new visual acuity chart.

The ability to identify letters of different size remains, in relation to the allowed effort, the most informative measure of visual capacity. Numerous letter charts have been produced with varying design, size, and size progression of the letters. Attempts to 'standardize' letter testing have been fruitless. In Sweden, the most commonly used letter charts show deficiencies in letter selection, size, and progression. In the present study, letter legibility was studied. 10 letters of average legibility were selected and a new chart constructed using these letters in sizes corresponding to acuities from 0.1 to 2.0. A geometric size progression was found optimal (factor 1.26).

Humans↗
PubMed1983

A monoclonal antibody-enzyme immunoassay for serum carcinoembryonic antigen with increased specificity for carcinomas.

A two-site monoclonal antibody-enzyme immunoassay (MEIA) for carcinoembryonic antigen (CEA) was developed that uses two monoclonal anti-CEA antibodies, which recognize two different epitopes in the peptide moiety of CEA. The assay was sensitive to 0.5 micrograms/liter and had a measuring range of 0.5-200 micrograms of CEA per liter. It was highly specific inasmuch as none of three known CEA-related substances, "nonspecific crossreacting antigens 1 and 2" (NCA-1 and NCA-2) and biliary glycoprotein I (BGP I), reacted in the assay. NCA-2 (meconium antigen) is very similar to CEA. None of five commercially available CEA assays were able to differentiate between CEA and NCA-2. With one exception (colon), normal tissue extracts did not react in the MEIA even when tested at very high concentrations. Sera from a total of 180 healthy individuals and patients with malignant and nonmalignant disease were analyzed for CEA levels by using the MEIA and in parallel a conventional radioimmunoassay. A significant increase in specificity for carcinomas was obtained with the MEIA. This was essentially due to a decrease of MEIA CEA values in sera from patients with nonmalignant disease. The CEA values in the group of carcinoma patients (colon, pancreas, lung, and breast) were the same in the two assays.

Antibodies, Monoclonal↗
PubMed1983

Colour vision and spectral sensitivity in children with visual handicaps.

In children with a visual handicap, colour vision testing may provide additional cues to diagnosis. Some information is given by pseudo-isochromatic plates. More informative are the arrangement tests, especially the Panel D-15. These tests can be used also in cases with severely reduced visual acuity. In suspected achromatopsia, the scotopic spectral sensitivity can be revealed by the D-15 test, the anomaloscope, or measuring the spectral sensitivity.

Age Factors↗