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Biomedical subjects

K Fogh

Publications and source records attributed to K Fogh.

At least 19 recordsLinked to original sources
PubMed2004

Effect of new manganese contrast agent on tissue intensities in human volunteers: comparison of 0.23, 0.6 and 1.5 T MRI, a part of a phase I trial.

To evaluate the effect of a new oral manganese contrast agent (CMC-001) on magnetic resonance imaging (MRI) intensities at different magnetic field strengths. Twelve healthy volunteers underwent abdominal MRI 1 week before and within 2.5-4.5 h after CMC-001 (MnCl(2) and absorption promoters dissolved in water) intake at three different MR scanners of 0.23, 0.6 and 1.5 T. Image contrast and intensity enhancement of liver and pancreas were analysed relatively to muscle and fat intensities. Manganese blood levels were followed for 24 h. Whole-blood manganese concentration levels stayed within the normal range. The liver intensities on T2w images decreased about 10% for the 1/2 contrast dose and about 20% for the full contrast dose independent of the field strength. The liver intensities on T1w images increased more than 30% for 1/2 contrast dose and over 40% for full contrast dose. The maximum T1 enhancement was achieved at the highest field. Pancreas intensities were not affected. Contrast between liver, muscle and fat intensities increased with magnetic field, as well as standard errors of the volunteer-averaged intensities. Oral intake of CMC-001 influences liver intensities and does not affect pancreas intensities at different magnetic field strengths.

Abdomen↗
PubMed2000

Recent developments in vitamin D analogs.

Within the past decade it has been shown that psoriasis can be treated topically with analogs of vitamin-D3. Impaired differentiation and increased proliferation of keratinocytes are key features in psoriatic lesions together with a local activation of T lymphocytes. Evidence has accumulated showing that analogs of vitamin D3 increase differentiation and inhibit proliferation of keratinocytes. Therefore, analogs of vitamin D3 have been investigated in a number of trials showing improvement of psoriasis. It has been shown that vitamin D analogs are better than their vehicle and show the same potency as potent topical steroids. However, vitamin D analogs have been proven efficacious and without side effects also when used on long term basis. Vitamin D analogs can be used both as monotherapy and in combination topical steroids, UVB, PUVA, retinoids and cysclosporine. The vitamin D3 analog calcipotriol has been investigated in most detail and is available as an ointment, a creme and as a scalp solutation. From clinical studies involving thousands of patients, it can be concluded that calcipotriol is efficacious, safe, well tolerated and can be used on a long term basis. Other analogs are available, however, these analogs have not been studied in greater details yet.

Calcitriol↗
PubMed1998

[Toxic epidermal necrolysis after treatment with lamotrigine].

A case of toxic epidermal necrolysis following treatment with lamotrigine is presented. A 20 year old male suffering from epilepsy was treated with lamotrigine in addition to valproic acid. After three weeks he developed cutaneous manifestations of Steven-Johnson's syndrome followed by toxic epidermal necrolysis, mucosal lesions and liver symptoms. He was treated with systemic corticosteroids, antibiotics and intravenous fluid, and recovered after a few weeks.

Adult↗
PubMed1997

Upregulation of vitamin D receptor levels by 1,25(OH)2 vitamin D3 in cultured human keratinocytes.

The natural biologically active form of vitamin D3, 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), possesses antiproliferative, prodifferentiating and immunomodulatory properties. The actions of 1,25(OH)2D3 are mediated through the intracellular vitamin D receptor (VDR), and the level of VDR is believed to determine the cellular responsiveness to vitamin D3. In the present study we examined the effects of 1,25(OH)2D3 on the expression of VDR and its message in cultured human keratinocytes. Western analysis showed the mean VDR content to be higher in undifferentiated cultures (175 pg/microgram protein) than in differentiated cultures (90 pg/microgram protein). Incubation with 1,25(OH)2D3 induced an increase in the VDR in both undifferentiated and differentiated keratinocytes. The VDR increase was detectable after 2 h and maximal (approximately two-fold stimulation) after 8 h. The 1,25(OH)2D3-induced stimulation of VDR levels was dose dependent with a maximum at 10(-7) M. The VDR mRNA levels as determined by the ribonuclease protection assay showed a peak (50% stimulation) after approximately 2 h. Although this increase in VDR mRNA was not statistically significant, the results indicate that the ligand-induced upregulation of VDR involves increased transcription. The upregulation of VDR levels may increase the responsiveness to 1,25(OH)2D3 and may, therefore, be an important mechanism for regulating the effects of 1,25(OH)2D3 on keratinocyte proliferation and differentiation.

Calcitriol↗
PubMed1996

All-trans retinoic acid inhibits binding of 1,25-dihydroxy-vitamin D3 to the vitamin D receptor in cultured human keratinocytes.

Psoriasis is characterized by hyperproliferation and impared differentiation of epidermal keratinocytes (KCs). Psoriasis can be treated with derivatives of retinoic acid (RA) and vitamin D3. Analogues of vitamin D3 are able to inhibit proliferation and stimulate differentiation of KCs. In contrast, RA inhibits terminal differentiation of KCs. Interactions are known to occur between RA and vitamin D3 signalling pathways. The purpose of the present study was to determine the effect of all-trans RA on the binding of 1,25-dihydroxy-vitamin D3 (1,25 (OH)2D3) to the vitamin D3 receptor (VDR) of cultured human KCs. Cultured KCs from normal adults were incubated with or without RA (10-9-10-7M) for 4-24 h. Cells were then harvested, homogenized and ultrasonicated. The extracted protein was incubated with 3H-1,25 (OH)2D3 (0.015-1.0 nM) with or without 250-fold excess nonradioactive 1,25 (OH)2D3 for 24 h and specific binding was determined by use of the dextran coated charcoal binding assay. Western blot analysis utilizing the monoclonal antibody 9A7 gamma to VDR was performed on protein extracted from the KCs. The bands resulting from Western blot analysis were visualized by enhanced chemiluminescence. From Scatchard analysis it was found that KCs bind 1,25 (OH)2D3 with high affinity (Kd = 0.175 nM). This binding was dose and time dependently inhibited by RA (60% inhibition at 10-7 M after 24 h of incubation). By Western blot analysis, RA had no effect on the amount of protein extracted from KCs at any of the RA concentrations tested. In conclusion, these results show that binding of vitamin D3 to its receptor of human KCs can be inhibited markedly by RA without effecting the amount of protein. These results are in contrast to results with other cell types in which RA upregulates binding of 1,25 (OH)2D3 to the VDR. Because interaction between retinoids and vitamin D3 may occur at different levels during signal transduction, it is not possible to predict from our results whether RA will inhibit the effects of vitamin D3 in vivo.

Calcitriol↗
PubMed1996

Normal levels of the vitamin D receptor and its message in psoriatic skin.

Treatment with vitamin D3 analogs improves psoriasis. The vitamin D receptor (VDR) mediates most, if not all, the effects of vitamin D3. The purpose of this study was to determine the levels of the VDR mRNA and VDR protein in normal and in involved and uninvolved psoriatic skin. Although VDR mRNA was not detected by Northern analysis of human skin samples, it was readily detectable by use of the more sensitive ribonuclease protection assay. The VDR mRNA levels were normal in acute guttate as well as in chronic plaque lesions. There was also no difference in VDR mRNA levels between normal and uninvolved psoriatic skin. The VDR protein was detected by Western analysis using the monoclonal 9A7 gamma anti-VDR antibody and a polyclonal rabbit anti-VDR antibody. For comparison, VDR levels were analyzed in cultures of normal human keratinocytes and the epithelial cell line MCF-7. Studies of the extraction procedures for VDR showed that at least 60% of Escherichia coli-expressed VDR added to the skin biopsy specimens was recovered. The VDR concentration in normal human adult skin was approximately 50 pg/microgram protein, and the concentrations of VDR in involved and uninvolved psoriatic skin were of the same order of magnitude. Using the 9A7 gamma anti-VDR antibody, the VDR (M(r) 53,000) was constantly present in lower amounts than a band of M(r) 80,000 in both skin specimens and keratinocyte cultures. This high-molecular-weight band is most likely a cross-reacting protein not related to VDR, because it was absent when using the polyclonal anti-VDR antibody.

Adult↗
PubMed1995

[Toxic epidermal necrolysis following intake of vitamins and natural medication].

Toxic epidermal necrolysis (TEN) is a rare but very severe cutaneous disorder characterized by necrosis of keratinocytes producing a loosening of the epidermis. As a consequence, life threatening dehydration and severe infections may occur. In most cases TEN occurs as a result of an adverse reaction to drugs. In the present case report, a 48 year-old female is suspected of having TEN due to the consumption of extremely large doses of vitamins, minerals and natural medicine in an attempt to treat a suspected collagenosis. After six months on this natural medication she developed a universal macular rash that progressed to TEN. She lost the epidermis over approximately sixty percent of her body surface and the condition was complicated by septicaemia and dehydration. After treatment with high doses of systemic corticosteroids and relevant antibiotics, she made a full recovery over the next three months. Attention should be paid towards excessive intake of vitamins and minerals and excessive use of natural medication.

Adrenal Cortex Hormones↗
PubMed1993

Expression, purification, and binding properties of human cellular retinoic acid-binding protein type I and type II.

Human cellular retinoic acid-binding protein (CRABP) type I and type II were expressed in Escherichia coli from cloned cDNAs. Expressed proteins were purified by gel filtration and ion-exchange chromatography, resulting in highly pure proteins. The yield after gel filtration was approximately 50 mg/liter bacterial culture. In binding studies the equilibrium dissociation constant, Kd, of retinoic acid (RA) for E. coli-derived CRABP-I and CRABP-II was 6.8 and 39 nM, respectively. The Kd of the synthetic retinoid analog CD 367 was 2.2 nM for CRABP-I and 3.0 nM for CRABP-II. RA competed with the binding of CD 367 to CRABP-I and CRABP-II with IC50 values of 20.0 and 90.0 nM, respectively. Retinoid analogs competed with the binding of CD 367 to CRABP-I and CRABP-II in the following order: (p-[(E)-2-(5,6,7,8-tetrahydro-5,5,8,8- tetramethyl-2-naphtyl)-1-propenyl]-benzoic acid (TTNPB) > 4-oxo-RA > 4-OH-RA > 13-cis-RA = 9-cis-RA. m-carboxy-TTNPB and CD 271 were found not to compete with the binding of CD 367 to CRABP-I or CRABP-II even at 500-fold molar excess. These data demonstrate that E. coli-derived CRABP-I has a higher affinity for RA than CRABP-II and that retinoic acid metabolites have a lower affinity for these proteins. The observed difference in affinity for RA supports the idea that CRABP-I, which is constitutively expressed, and CRABP-II, which is induced by RA, have different functions in the cell. In addition, 9-cis-RA, a natural ligand for the retinoid X receptors, is not a physiological ligand for either CRABP-I or CRABP-II.

Binding, Competitive↗
PubMed1993

Leukotriene B4 formation during human neutrophil keratinocyte interactions: evidence for transformation of leukotriene A4 by putative keratinocyte leukotriene A4 hydrolase.

In the present study, keratinocytes were coincubated with human neutrophils to determine whether or not an increase in leukotriene B4 formation can occur. Human keratinocytes used were cultured in serum-free, low-calcium medium, whereas neutrophils were purified from heparinized venous blood. After coincubations, formation of leukotriene B4 was determined by reversed-phase high-performance liquid chromatography, coupled with its characteristic UV scan. Confirmation and quantification was by radioimmunoassay. Our data revealed that incubations of keratinocytes (1.5 x 10(6)) alone stimulated with calcium ionophore resulted in no detectable amounts of leukotriene B4. In contrast, incubations of neutrophils (5 x 10(6)) alone resulted in the generation of 62.2 +/- 8.5 ng of LTB4. Coincubations of the neutrophils with keratinocytes (ratio 3:1) resulted in a 56-163% increase in leukotriene B4 formation. To delineate the source of the newly formed leukotriene B4, incubations of keratinocytes with leukotriene A4 revealed that keratinocytes can transform leukotriene A4 into leukotriene B4. These latter findings indicate that although keratinocytes cannot directly metabolize arachidonic acid into leukotriene B4 via the 5-lipoxygenase enzyme, they can transform neutrophil-derived leukotriene A4 into leukotriene B4, thus indicating the possible existence of a putative keratinocyte-leukotriene A4 hydrolase. It is therefore reasonable to speculate that the keratinocytes possess the capacity to generate leukotriene B4 in the epidermis when provided leukotriene A4 and thereby can amplify the inflammatory processes occurring during neutrophil exocytosis. These findings indicate that transcellular metabolism of arachidonic acid metabolites in the epidermis by keratinocytes and neutrophils may contribute to the high levels of leukotriene B4 in lesional skin of inflammatory skin diseases.

Arachidonic Acid↗
PubMed1993

Modulation of eicosanoid formation by lesional skin of psoriasis: an ex vivo skin model.

The purpose of the present study was to develop an ex vivo skin model to determine the capacity of lesional skin of psoriasis to form leukotriene B4 and other eicosanoids. Keratomed skin samples were incubated in the presence of the calcium ionophore A23187 and arachidonic acid for 45 min at 37 degrees C. After extraction of lipids, eicosanoids were determined by quantitative reversed-phase high-performance liquid chromatography in combination with specific radioimmunoassays. We found that stimulation of skin samples with A23187 and arachidonic acid increased the amount of leukotriene B4 4.0-fold. The 12-lipoxygenase product, 12-hydroxy-eicosatetraenoic acid, and the 15-lipoxygenase product, 15-hydroxy-eicosatetraenoic acid, were both increased 2.7-fold. The cyclooxygenase product, prostaglandin E2, was increased 8.0-fold. Similar incubations using psoriatic scales did not result in formation of eicosanoids. Incubations with the 5-lipoxygenase inhibitor RS43179 inhibited the formation of leukotriene B4 and prostaglandin E2 without significantly affecting the formation of 12-hydroxy-eicosatetraenoic acid and 15-hydroxy-eicosatetraenoic acid. These results reveal that lesional psoriatic skin ex vivo has the enzymatic capacity to increase the levels of eicosanoids. This provides an ex vivo skin model to determine whether putative lipoxygenase inhibitors are able to modulate the formation of eicosanoids in psoriatic skin.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1992

Effect of dihomogammalinolenic acid and its 15-lipoxygenase metabolite on eicosanoid metabolism by human mononuclear leukocytes in vitro: selective inhibition of the 5-lipoxygenase pathway.

The purpose of the present study was to determine the effect of the n-6 fatty acid, dihomogammalinolenic acid (DGLA, 20: 3, n-6) on arachidonic acid (AA) (C20: 4) metabolism by human peripheral mononuclear leukocytes (HPML). After incubation of HPML with A23187 (5 microM) and DGLA, the cyclooxygenase (CO) and lipoxygenase (LO) products were separated and quantified by reversed-phase high-performance liquid chromatography (RP-HPLC) combined with radioimmunoassay. DGLA led to no change in PGE2 formation, but at similar concentrations there was a dose-dependent decrease in LTB4 formation (IC50 = 45.0 microM). The inhibition of LTB4 formation by DGLA was associated with a dose-dependent increase in its 15-LO metabolite 15-hydroxyeicosatraenoic acid (15-HETrE) and its CO metabolite prostaglandin E1 (PGE1). Incubation of HPLM with 15-HETrE (0-1.5 microM) alone did not result in a change in PGE2 formation, whereas 15-HETrE was a much more potent inhibitor of LTB4 formation (IC50 = 0.5 microM) than DGLA. These results show that the addition of DGLA to HPML results in a selective inhibition of LTB4 formation, presumably via its metabolite (15-HETrE).

8,11,14-Eicosatrienoic Acid↗
PubMed1992

Interleukin-8 stimulates the formation of 15-hydroxy-eicosatetraenoic acid by human neutrophils in vitro.

Interleukin-8 (IL-8), is a potent activator of polymorphonuclear leukocyte (PMN) functions including chemotaxis, superoxide anion production, and enzyme release and it is also chemotactic for lymphocytes. Additionally, it has recently been shown that IL-8 stimulates the formation of 5-lipoxygenase (LO) products of arachidonic acid (AA) by human PMNs. The purpose of the present study was to determine whether IL-8 also might affect the formation of 15-LO products from AA. Purified PMNs in phosphate buffered saline were preincubated with and without exogenous AA (10(-5)-10(-4) M) for 10 min. Then IL-8 was added in biologically relevant concentrations ranging from 0.1 to 100 ng/ml and incubation was carried out for 5 min at 37 degrees C. Lipids were then extracted from supernatants, and eicosanoids were determined by quantitative RP-HPLC. Compared with unstimulated cells, IL-8 resulted in a dose dependent increase in both LTB4 and 15-HETE (up to 125% and 40% at 100 ng/ml, respectively). This increase in eicosanoid formation required the presence of exogenous AA. These results indicate that IL-8 is both a potent stimulator of 5-LO activity and of 15-LO activity. LTB4 can induce both inflammation and contribute to hyperproliferation in the skin. 15-HETE in contrast has the ability to inhibit the effects induced by LTB4. Because IL-8 is able to stimulate both LTB4 and 15-HETE formation, the effect of IL-8 as a putative regulator of inflammatory processes may be dependent on the relative stimulation of 5-LO and 15-LO.

Chromatography, High Pressure Liquid↗
PubMed1991

Linoleic acid and dihomogammalinolenic acid inhibit leukotriene B4 formation and stimulate the formation of their 15-lipoxygenase products by human neutrophils in vitro. Evidence of formation of antiinflammatory compounds.

Enzymatic transformation of the n-6 polyunsaturated fatty acid (PUFA) arachidonic acid (AA) by the 5-lipoxygenase (LO) enzyme results in the formation of leukotrienes (LTs) including leukotriene B4 (LTB4), which is a potent mediator of inflammation. The purpose of the present study was to determine the effect of other n-6 fatty acids on the formation of LTB4 by human neutrophils and to determine if these n-6 fatty acids themselves may be transformed into products with antiinflammatory capacity. Purified neutrophils isolated from heparinized human venous blood were incubated with A23187 (5 microM) and different concentrations (0-100 microM) of the n-6 fatty acids linoleic acid (LA) and dihomo-gamma-linolenic acid (DGLA). LO products were determined by use of quantitative reversed-phase high performance liquid chromatography (RP-HPLC) and mass spectrometry. The formation of LTB4 was dose dependently inhibited by both LA (IC50 = 45 microM) and DGLA (IC50 = 40 microM). This inhibition of LTB4 formation was associated with a dose dependent increase in the formation of the respective 15-LO products of LA (13-hydroxy-octadecadienoic acid; 13-HODE) and DGLA (15-hydroxy-eicosatrienoic acid; 15-HETrE). To determine whether these 15-LO products themselves might inhibit LTB4 formation, neutrophils were incubated with 13-HODE and 15-HETrE. Both 15-LO products lead to a dose-dependent inhibition of LTB4 formation (IC50 = 7.5 microM and IC50 = 0.2 microM). For comparison the 15-LO product of AA, 15-hydroxy-eicosatetraenoic acid (15-HETE), also inhibited LTB4 formation (IC50 = 0.75 microM).(ABSTRACT TRUNCATED AT 250 WORDS)

8,11,14-Eicosatrienoic Acid↗
PubMed1991

Long-term efficacy and tolerability of topical calcipotriol in psoriasis. Results of an open study.

Calcipotriol is a non-calcaemic vitamin D3 analogue. In short-term studies, topically applied calcipotriol is both efficacious and safe for the treatment of psoriasis vulgaris. The purpose of the present study was to determine the efficacy and safety of calcipotriol ointment in patients treated for approximately 6 months. Fifteen patients with plaque-type psoriasis were treated daily with calcipotriol ointment 50 micrograms/g. After treatment for 6 weeks there was a significant alleviation of erythema, infiltration and scaling. This degree of improvement was maintained throughout the study, except in one patient, who was withdrawn at week 15 because of minimal improvement. At the end of treatment, 80% of the patients showed a moderate improvement at least. Local adverse events occurred in 3 patients. These were mild and transient. Hypercalcaemia or other laboratory abnormalities did not develop in any patient. Morphometric examination of biopsies taken from perilesional skin (i.e. skin exposed to calcipotriol) at the end of treatment did not show signs of epidermal or dermal atrophy compared with uninvolved psoriatic skin. Although only a limited number of patients participated in the study, these results indicate that calcipotriol ointment 50 mu/g is both efficacious and safe for the long-term treatment of psoriasis.

Administration, Cutaneous↗