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Biomedical subjects

K Wickström

Publications and source records attributed to K Wickström.

13 recordsLinked to original sources
PubMed2000

Qualitative and quantitative end-group analysis of a small molecular weight polyester by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry was used for qualitative and quantitative end-group analysis of a small molecular weight polyester, poly(2-butyl-2-ethyl-1,3-propylene phthalate). The presence of carboxyl-terminated linear and cyclic polyester oligomers was confirmed with the help of simple sample preparation methods. The presence of carboxyl end-groups in the polyester chains was verified through their formation of carboxylate salts with alkali metal cations. Cyclic oligomers were identified through deuterium exchange of the exchangeable protons of the polyester. Various inorganic salts were tested for salt formation of the carboxyl end-groups, but only the alkali metal salts proved effective. The influence of the alkali metal salts on the results of the quantitative end-group analysis was also studied. The relative amounts of differently terminated and cyclic oligomers were calculated when the alkali metal salts were used with different matrices. The results showed that both the salts and the matrices used in sample preparation can have a marked effect on the quantitative results of the end-group analysis. The measurements were carried out using 2,5-dihydroxybenzoic acid (DHB), 1,8, 9-trihydroxyanthracene (dithranol), and 2-(4-hydroxyphenylazo)benzoic acid (HABA) as matrix compounds. Dithranol and HABA repeatably exhibited similar results, and these results differed from those obtained with DHB probably because of the different ionization mechanisms in the MALDI process.

Carboxylic Acids↗
PubMed2000

Preventing lens epithelial cell migration using intraocular lenses with sharp rectangular edges.

PURPOSE: To compare the preventive effect on posterior capsule opacification (PCO) of an acrylic intraocular lens (IOL) and a silicone IOL, both with sharp rectangular optic edges. SETTING: Jinshikai Medical Foundation, Nishi Eye Hospital, Osaka, Japan. METHODS: After phacoemulsification, an acrylic IOL (AcrySof(R)) was implanted in 1 eye and a silicone IOL (CeeOn 911) in the contralateral eye of 7 rabbits, one of which was omitted from evaluation. RESULTS: The Miyake-Apple view and histopathological findings 3 weeks after surgery revealed that the lens capsule wrapped tightly around the optic edges, conforming to a distinctly sharp bend, with both IOL types in 5 rabbits. Migrating lens epithelial cells (LECs) were inhibited at the site. The AcrySof IOL had a better capsular bend effect in the histological sections, but there was no apparent difference in PCO development between the 2 IOLs. CONCLUSIONS: The CeeOn 911 silicone IOL, with sharp rectangular optic edges, showed an effect on preventing PCO that was similar to that of the AcrySof IOL. When a discontinuous capsular bend is created by an IOL with sharp optic edges, the bend may induce contact inhibition of migrating LECs regardless of the lens' material composition.

Acrylic Resins↗
PubMed1998

Effect of cataract surgery on aqueous TGF-beta and lens epithelial cell proliferation.

PURPOSE: To study lens epithelial cell (LEC) regulation after experimental cataract surgery in rabbits. The effect of aqueous humor (AqH) on LECs in vitro was investigated and the AqH concentrations of basic fibroblast growth factor (bFGF) and transforming growth factor-beta (TGF-beta) were determined. METHODS: Aqueous humor was aspirated immediately before, and 1, 5, 10, 15, and 30 days after cataract surgery (n=8 each day). The effect of AqH on LEC proliferation was investigated by the incorporation of [3H]thymidine. The following concentrations were determined in AqH: bFGF, active and total TGF-beta, leukocytes, and total protein. RESULTS: Aqueous humor collected after surgery triggered LEC growth on each occasion, except on (postoperative) day 30, in contrast to the effect of normal AqH. Lens epithelial cell proliferation peaked on day 1, displaying a sixfold increase. The bFGF concentration in AqH increased 6 to 10-fold after surgery and remained high throughout the experimental period. The AqH concentration of active TGF-beta decreased sevenfold 1 day after surgery. It then returned to normal levels on day 15. Total TGF-beta in postoperative AqH was twice as high as that in normal AqH on all days. Lens epithelial cell proliferation correlated with protein (r=0.685), leukocytes (r=0.565), and active TGF-beta (r=-0.418). CONCLUSIONS: The stimulating effect of postoperative AqH on LEC proliferation may be caused by a reduction in the concentration of TGF-beta.

Animals↗
PubMed1997

Analysis of odour and taste problems in high-density polyethene.

The compounds that cause off-flavours in plastics, have been recognized mainly as carbonyl compounds (aldehydes, ketones and esters). They occur in low concentrations, and due to their low-threshold odour concentrations, their typical odours were identified. Most of these off-flavour compounds are volatile. Chemical analysis of smelling compounds requires a very sensitive method with a high-resolution capability. The analysis of volatile organic compounds (VOCs) in high density polyethene (HD-PE) granules and waters in which the granules have been shaken for 4 h, were carried out by gas chromatography-mass spectrometry-sniffing system (GC-MS-SNIFF) and by gas chromatography-fourier transform infrared spectroscopy-sniffing system (GC-FTIR-SNIFF). A purge-and-trap technique was used to introduce the VOCs from samples into the gas chromatograph. Leaching waters of HD-PE granules were also evaluated by panel. This panel agreed upon six descriptive attributes for odour: sweet, chemical, stale, dusty, foul and floor-cloth. The attributes for taste were: sweet, metallic, stony, pungent, dusty, plastic, foul, stink bug and candle grease.

Chromatography, Gas↗
PubMed1997

Inflammatory response after endocapsular phacoemulsification or conventional extracapsular lens extraction in the rabbit eye.

PURPOSE: We compared the inflammatory response after phacoemulsification and conventional extracapsular lens extraction in New Zealand albino rabbits. METHODS: One eye was selected at random and phacoemulsification was performed. Extracapsular lens extraction was done in the fellow eye. In both eyes a polymethylmetacrylate intraocular lens was implanted into the capsular bag and the wound was sutured with a 9-0 polypropylene continuous suture. The levels of prostaglandin E2 in aqueous humour and wet mass of the iris-ciliary bodies were measured at day 1. The number of white blood cells and protein levels in the aqueous humour were measured at day 1, 3, 7, 14 and 30. Corneal thickness was estimated with pachymetry. RESULTS: Prostaglandin E2 levels and wet masses of iris-ciliary bodies were significantly higher after extracapsular lens extraction, which also induced significantly higher white blood cells counts at day 1 and 3 and higher protein levels at day 7. Extracapsular lens extraction caused more corneal edema at day 3, 7 and 14. CONCLUSION: The results suggest that phacoemulsification induced less surgical trauma with less breakdown of the blood-aqueous barrier.

Animals↗
PubMed1993

The effect of transforming growth factor-alpha (TGF alpha) on rabbit and primate lens epithelial cells in vitro.

TGF alpha, a member of the epidermal growth factor family stimulates proliferation of various cells. In the search for molecules that regulate cell division in the lens epithelium, the effect of numerous growth factors including EGF and FGF has been determined. In this study, the effect of TGF alpha on lens epithelial cells (LEC) from rabbit and monkey was investigated and compared to FGF and EGF. Since TGF alpha is suggested to be a factor that is regulated by auto and/or paracrine mechanisms, an immunohistochemical visualisation of the factor in the rabbit lens in situ was performed. TGF alpha stimulates LEC in a dose-dependent manner with a maximal threefold increase in cellular proliferation at 100 ng/ml. At a concentration above 10 ng/ml the cells lost their epithelial morphology and became irregular and star-shaped. Since TGF alpha is a potent LEC mitogen and has shown to increase in aqueous humour after trauma to the eye, this factor might be one of the molecules that regulate normal cell division in the ocular lens as well as LEC growth after cataract surgery.

Animals↗
PubMed1992

Polyamine and histopathological changes after unilateral endotoxin-induced uveitis and its contralateral effects.

The polyamines putrescine, spermidine and spermine are essential for normal cell function and proposed to be involved in inflammatory reactions. The polyamines were measured bilaterally in rabbit aqueous humor after unilateral endotoxin-induced uveitis. The contralateral eyes were injected with saline or not touched. Aqueous protein levels and leukocytes were determined and a histological evaluation was performed. Protein, leukocytes, putrescine and spermine increased in the treated eyes, but not in the untouched eyes. When saline was injected in the contralateral eye, a small increase in spermine was seen. Spermidine decreased first, but increased later, in both the endotoxin-injected and the other eye. Histopathologically, the treated eyes showed an infiltration of leukocytes, vasodilatation and in some cases optic nerve involvements. A mild reaction was also seen in the unchallenged contralateral eyes. The results show that polyamines might serve as a marker for acute inflammation in the eye and that the mechanism of putrescine and spermine induction is different from the one of spermidine. Polyamines are suggested to play a role in the cellular immune response.

Animals↗
PubMed1992

Aqueous humor polyamines and alkaline phosphatase activity in endotoxin-induced uveitis: correlations to diverse leukocyte subsets.

The polyamines putrescine, spermidine and spermine have been proposed to be a part of the acute phase inflammatory response. They have been shown to be useful markers for cellular kinetics and change with various pathological conditions. The hypothesis that aqueous humor polyamines could be used to follow the time course of an endotoxin-induced inflammation in the eye was investigated. Additional parameters studied were the amount of aqueous leukocytes, alkaline phosphatase activity, distribution of leukocyte subsets and breakdown of the blood-aqueous barrier. Aqueous leukocytes, protein, alkaline phosphatase activity, putrescine and acetylated spermidine increased significantly as a response to inflammation during the first days after uveitis induction. Spermidine decreased 24 h after injection and seemed to rise thereafter. The different polyamines, except spermidine, correlated to the diverse infiltrating leukocyte subsets. These observations indicate that aqueous polyamines may be applied as valid markers for inflammation in the eye.

Alkaline Phosphatase↗
PubMed1991

Polyamines in rabbit aqueous humor after surgical trauma to the eye.

The polyamines putrescine, spermidine and spermine are necessary for cellular growth and directly involved in cellular differentiation and cell death. The hypothesis that extracellular polyamine levels in rabbit aqueous humor could be used as biomarkers for trauma after eye surgery was investigated. Changes in polyamine levels in rabbit aqueous humor were measured after anterior chamber lens implantation and compared to normals. The measurements were made by reversed phase HPLC and 9-fluorenylmethyl chloroformate and fluorescence detection. An increase in protein concentration followed by a white blood cell mobilization in the aqueous humor is a response to trauma to the eye. Therefore, the polyamine levels were compared to the aqueous levels of protein and leukocytes. Three days postoperatively a significant increase in spermidine was observed and a significant correlation between elevated protein levels and elevated spermine as well as total polyamines were noticed. No correlation between a high number of leukocytes and high polyamine levels were found. The results suggest that polyamines are evident markers for surgical trauma response, but not necessarily correlated to the postoperative inflammatory phase and the infiltration of inflammatory cells.

Animals↗
PubMed1986

Polycyclic aromatic compounds (PAC) in leaf lettuce.

Twenty-three samples of leaf lettuce (Lactuca sativa var. crispa) cultivated in private gardens in southern Finland were analyzed for polycyclic aromatic hydrocarbons (PAH) and derivatives. The total PAH concentrations varied from 4.8 to 94 micrograms/kg fresh weight. Nitro derivatives of PAH were detected in only five samples. One lettuce sample was also analyzed for PAH oxy-derivatives. 9H-Fluoren-9-one (1.3 microgram/kg) and 6 H-benzo[cd]pyren-6-one (0.3 microgram/kg) were found. The profiles of PAH in lettuce were compared with those in ambient air. It was concluded that PAH in lettuce originate from deposition of PAH-containing particles present in ambient air.

Finland↗
PubMed1984

Polycyclic aromatic hydrocarbons in Finnish sauna air.

The concentrations of polycyclic aromatic hydrocarbons (PAH) in the air of three different types of wood-heated saunas were studied. The highest concentrations were found in the smoke sauna (total PAH 170-1550 micrograms/m3, benzo[a]pyrene 4.6-20 micrograms/m3) the second highest in the preheated sauna (total PAH 50-90 micrograms/m3, benzo[a]pyrene 3.4-4.5 micrograms/m3) and the lowest concentrations in the sauna heated by continuous burning of wood (total PAH 25 micrograms/m3, benzo[a]pyrene below 0.1 micrograms/m3). The results clearly indicate that regular bathing in the smoke sauna and in the pre-heated sauna increases the intake of PAH compounds (e.g. benzo[a]pyrene and benzo[a]anthracene).

Air Pollutants↗