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Biomedical subjects

I Dahlquist

Publications and source records attributed to I Dahlquist.

At least 19 recordsLinked to original sources
PubMed1990

Determination of warfarin in drinking water by high-performance liquid chromatography after solid-phase extraction.

A method for the determination of 0.1 micrograms/l of warfarin in drinking water involving concentration by solid-phase extraction is described. A 1000-ml volume of drinking water is aspirated through a solid-phase extraction column and warfarin is eluted to 1.0 ml. The eluate is analysed by reversed-phase high-performance liquid chromatography with UV detection. The detection limit is 0.02 micrograms/l. Recoveries of greater than 90% were obtained when tap water was spiked with warfarin.

Chromatography, High Pressure Liquid↗
PubMed1987

Contact allergy to the active ingredients of Kathon CG.

The preservative Kathon CG is a commercial preparation, consisting of 2 active ingredients and other components. 28 patients with contact allergy to Kathon CG participated in a study in which patch testing was performed with serial dilutions, and with 5 chromatographically separated fractions. All reacted to fraction IV, and 2 patients also to fraction II. Mass spectrometry and nuclear magnetic resonance spectrometry identified fraction II and IV to be the active ingredients; 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one.

Dermatitis, Contact↗
PubMed1986

Contact allergy to the preservative Kathon CG.

Of 976 patients routinely patch tested with Kathon CG (Rohm & Haas), 300 ppm, 43 (4.4%) gave a positive reaction. Of 170 patients routinely tested with Kathon CG 250 ppm, 10 (5.9%) gave a positive reaction. Out of 34 patients tested with serial dilutions of Kathon CG, 17 (50%) reacted to 100 ppm, 8 to 30 ppm and 2 to 10 ppm. The concentration of 1000 ppm of Kathon CG was irritant in some cases, but 300 ppm was not irritant. Of the 976 patients tested with Kathon CG 300 ppm, 8 (0.8%) showed a "flare-up" reaction, indicating patch test sensitization. Of the 170 tested with Kathon CG 250 ppm, 2 (1.2%) were sensitized. When the patch-test-sensitized patients were retested with serial dilutions, they showed the same pattern as the other patients. 13 sensitized patients were use tested and 7 (54%) gave responses. In the literature, Kathon CG 100 ppm is recommended as the routine patch test concentration. However, 50% of the sensitive persons may then be overlooked. In our clinics, Kathon CG has become the second most common contact sensitizer, but the sensitivity cannot be traced in all patients with clinically relevant allergy without an unacceptable risk of patch test sensitization.

Biopsy↗
PubMed1986

Demonstration of Kathon CG in some commercial products.

The preservative Kathon CG has become one of the most common sensitizers. It has, however, been difficult to explain the sensitization and to assess the clinical relevance of the contact allergy, partly due to lack of specification of the preservative in products. A high-performance liquid chromatography method was used to demonstrate Kathon CG in 123 commercial products of both "leave on" and "rinse off" types. 38 of these contained Kathon CG in the range of 1-15 ppm of active ingredients. There were no differences between "leave on" and "rinse off" products concerning the relative number of products containing Kathon CG and the concentrations of the preservative.

Allergens↗
PubMed1986

Immunoglobulin E antibodies against a reactive dye--a case report.

The presence of specific IgE (immunoglobulin E) antibodies against a conjugate between human serum albumin and a reactive azo dye (Levafix Goldgelb E-3GA, Reactive Orange 67) was demonstrated by the radioallergosorbent test (RAST), RAST inhibition, and skin prick tests in an occupationally exposed subject with symptoms of mainly rhinoconjunctivitis.

Adult↗
PubMed1984

A simple method for the detection of formaldehyde.

The commonly used chromotropic acid method for the determination of formaldehyde sometimes produces a masking discolouration. We have therefore evaluated a complementary method in which acetylacetone is used as the reagent. By a combination of the 2 methods, formaldehyde can be traced in most products.

Cosmetics↗
PubMed1984

An attempt to isolate and identify allergens in lanolin.

One sensitizer, a sterol, has previously been reported to be present in lanolin. In this study, a related substance, a sterol, with a molecular weight of 424 has been isolated. A few sensitive subjects did not react to this substance. Lanolin probably contains several sensitizers. Sensitization to lanolin in guinea pigs seems previously to have failed. In this study, a methanol extract of a lanolin preparation containing large amounts of sterols sensitized guinea pigs.

Allergens↗
PubMed1983

Contact allergy to trimethylolpropane triacrylate (TMPTA) in an aziridine plastic hardener.

4 workers developed hand and face dermatitis when exposed to a floor top coat. This contained a polyurethane and a polyfunctional aziridine hardener and additives. The aziridine hardener was made by reacting propyleneimine with a polyfunctional acrylate, trimethylolpropane triacrylate (TMPTA). All 4 reacted to the hardener and to TMPTA, which is present in excess. 2 of them also reacted to pentaerythritol triacrylate (PETA), which can be used in the production of aziridine hardeners. TMPTA and PETA cross-react, and are known sensitizers in UV-hardening acrylates. The present finding shows that well-known sensitizers can be found in hidden sources when used in a quite different chemical process.

Acrylates↗
PubMed1983

Effects of in vitro hyperthermia on human natural killer cells.

The present study demonstrates that human natural killer (NK) cells isolated from peripheral blood of normal individuals are highly sensitive to hyperthermia. The effect was time and dose dependent, and treatment of peripheral blood lymphocytes at 42 degrees for 1 hr almost completely abolished NK activity. The effect was not a consequence of cell death since only a small decrease in cell viability was observed and the viability of density gradient fractions enriched for NK activity was normal. Analysis of NK activity at the single-cell level by application of a conjugation assay in agarose revealed that hyperthermia interfered with target cell binding as well as the lytic cycle. Attempts to rescue NK activity after hyperthermia treatment by incubation overnight with human alpha-interferon or activation in mixed leukocyte culture was unsuccessful, indicating that even pre-NK cells are heat sensitive. In contrast, the proliferative response to alloantigens in mixed leukocyte culture and to the T-cell mitogen concanavalin A was unaffected. Hyperthermia exposure of cytotoxic T-lymphocyte generated in mixed leukocyte culture immediately before assay against allogeneic blast cells strongly inhibited their activity. Some alterations in the kinetics of stimulation with the B-cell mitogen Staphylococcus aureus bacteria were observed after heat exposure although maximal stimulation was at control levels. Thus, NK cells, including their precursors, seem to be preferentially sensitive to hyperthermia among various lymphoid subclasses.

Cells, Cultured↗