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B Bonnekoh

Publications and source records attributed to B Bonnekoh.

At least 55 records · Page 3Linked to original sources
PubMed1991

Structure-function relationship of new anthralin derivatives assayed for growth inhibition and cytotoxicity in human keratinocyte cultures.

HaCaT keratinocyte cultures were exposed to twelve hydrophilic anthralin derivatives 1 to 12 with substituents at C-1 and C-8 of the anthrone skeleton, of one H at C-10 and of both H's at C-10 by lacton rings. After 3 microM treatment growth was determined by cellular protein content, 3H-thymidine- and 14C-amino-acid-uptake and cytotoxicity by the release of cytoplasmic LDH into the culture medium. In comparison to acetone control (100%) anthralin suppressed mean protein content, as well as DNA- and protein-synthesis to 33, 28, and 21%, respectively, and the drug revealed an enzyme release of 660%. In relation to the parent drug we found similar cell growth inhibitory effects of compounds 4, 6, 8, 9, 10, and 12. Deriv. 4, 8, and 10 were, however, to some extent less cytotoxic than anthralin, whereas deriv. 6, 9, and 12 were in the same range. An extreme suppression of growth parameters which differed from the anthralin effect by a factor 0.5-0.8 was caused by deriv. 11, showing the same cytotoxicity. Deriv. 1, 2, 3, 5, and 7 did not demonstrate any cytotoxicity. Concerning growth parameters, deriv. 2 induced a slight stimulation, deriv. 3 and 7 were completely ineffective, deriv. 1 and 5 induced slightly to moderately inhibited proliferation but both being much less effective than anthralin. These data indicate that the "minimum structure" concept by Krebs and Schaltegger--claiming 1-hydroxy-9-anthrone as a precondition for clinical antipsoriatic potency--is not valid at least in cell-biological tests and point toward possible usefulness of some experimental model compounds as alternative antipsoriatics.

Anthralin↗
PubMed1991

Effects of tiflucarbine as a dual protein kinase C/calmodulin antagonist on proliferation of human keratinocytes and release of reactive oxygen species from human leukocytes.

Various studies have suggested that calmodulin (CaM) is involved in the pathophysiology of psoriasis. Protein kinase C (PKC) is also accepted as playing a regulatory role in cell proliferation as well as in inflammatory processes. Therefore, we investigated the effects of the known CaM antagonist tiflucarbine (BAY/TVX P 4495) on two cellular systems related to the major clinical symptoms of psoriasis: proliferation of cultured human keratinocytes (HaCa T cell line) and release of reactive oxygen species (ROS) from human polymorphonuclear leukocytes (PMNL). Tiflucarbine inhibited both cellular responses in a dose dependent manner. Furthermore, tiflucarbine directly affected PKC, and may thus be considered to be a dual PKC/CaM antagonist with putative antipsoriatic activity. The effects of tiflucarbine on the different parameters were compared with those of the structurally unrelated dual PKC/CaM inhibitor W-7 and those of the potent PKC inhibitor staurosporine. The potencies of all three compounds were found to be in the same range as their PKC-inhibiting potency. Our data indicate that PKC, rather than CaM, may play a regulatory role in the release of ROS as well as in keratinocyte proliferation. Therefore, inhibition of PKC in general might have a therapeutic benefit in psoriasis.

Alkaloids↗
PubMed1991

Repeated treatment with dithranol induces a tolerance reaction in keratinocytes in vitro.

The hyperproliferative human keratinocyte line (HaCaT) was tested for dithranol tolerance (tachyphylaxis) at the cellular level. At day 4 after seeding, keratinocytes were treated with 0.3 or 1.0 microM dithranol. Data were compared with those from experiments including additional pretreatments with 0.3 microM at day 3, or at days 1 and 3. Protein content, DNA synthesis and protein synthesis (incorporation of 3H-thymidine and 14C-amino acids per protein) were determined at 24, 48 and 72 h after the last drug exposure. Protein content of attached cells decreased in relation to dose and frequency of treatments. Inhibition of DNA and protein synthesis (38.2% and 32.3%, respectively) also occurred 24 h after a single treatment with 0.3 microM dithranol, but was only 18.4% and 9.1% after pretreatment twice with 0.3 microM dithranol. This tolerance reaction in vitro, after repeated dithranol exposure of human keratinocytes, may be explained by a selective loss of drug-sensitive cells.

Anthralin↗
PubMed1991

Antiproliferative potential of zidovudine in human keratinocyte cultures.

Because the beneficial effects of zidovudine in human immunodeficiency virus infection-associated psoriasis have recently been observed, this study focused on the drug's action on the rapidly proliferating human HaCaT keratinocyte line as an in vitro model for epidermal hyperproliferation. Cultures in log growth phase were exposed to zidovudine for 2 days. Zidovudine slowed proliferation in a dose-dependent fashion as evidenced by 50% inhibition concentrations of 33 mumol/L (cell number), 30 mumol/L (protein content), 0.9 mumol/L (protein synthesis), and 0.7 mumol/L (DNA synthesis). Significant (p less than 0.01) reduction of cell viability to 94.6% and 87.2%, as well as morphologic manifestations of cytotoxicity, were first evident after 2 days' exposure to maximal drug concentrations of 10 and 100 mumol/L, respectively. Control viability, assayed by trypan blue exclusion, was 98.0%. Direct cytotoxic plasma membrane injury could be ruled out by the absence of any increase in cytoplasmic lactate dehydrogenase release into supernatants at least during the 1 day of maximal dosage exposure. The drug-induced inhibition of proliferation was reversible within 7 days after a 2-day exposure to 100 mumol/L zidovudine. Two days of treatment with a 10 mumol/L dose did not alter the pattern and synthesis of keratins in vitro. Thus the known antipsoriatic efficacy of zidovudine might be explained, at least partly, by the drug's cytostatic potency.

Amino Acids↗
PubMed1991

Increase of lipid fluidity and suppression of proliferation resulting from liposome uptake by human keratinocytes in vitro.

The in vitro effects of liposomes on HaCaT human keratinocytes were studied with regard to their uptake, lipid fluidity and proliferation of the cells. Oligolamellar liposomes, prepared from soya bean phospholipids, had a mean size of 150 mm and consisted predominantly of phosphatidylcholine (83%) and phosphatidylethanolamine (10%) and the fatty acids comprised mainly linoleic acid (66%) or other unsaturated fatty acids. After 6 and 24 h of incubation with 1 and 0.1% w/v of liposomal lipids, phase-contrast microscopy revealed marked cytoplasmic vacuolization of the cells. Keratinocytes treated with the liposomes contained aggregations of multilaminated lipid material without delimiting cell membranes. The cellular lipid fluidity (reciprocal of diphenylhexatriene fluorescence polarization P-value) correlated with liposomal concentration and incubation time. A significant elevation of lipid fluidity (P less than 0.05) was observed with 1 and 0.1% liposomes after 1 h of incubation (81.8 +/- 4.7 and 95.7 +/- 1.2% of control P value) and for 0.01% liposomes after 3 h (96.2 +/- 1.5%). Maximum fluidity occurred after 48 h of exposure to 1% liposomes (42.1 +/- 3.1%). Exposure to liposomal lipids for 24 and 48 h resulted in suppressed cell proliferation with 50% inhibition concentrations (IC50), being 0.06% for incorporation of [3H]-thymidine. 0.08% for [14C]-amino-acid incorporation and greater than 1% for protein content per well after 24 h of exposure. The cells were able to proliferate and lipid fluidity returned to normal within 7 days following discontinuation of incubation with liposomal lipids.

Cell Division↗
PubMed1991

Long-term cultured adult human keratinocytes secrete granulocyte-macrophage colony-stimulating factor but not interleukin-3 after cytokine exposure in vitro.

To investigate the secretion of granulocyte-macrophage colony-stimulating factor (GM-CSF) and of interleukin-3 (IL-3) by human keratinocytes in vitro, adult human keratinocytes (aHKc) from 3 different donors and a spontaneously transformed keratinocytic line (HaCaT) were cultured and exposed to various cytokines and to the protein kinase C-activating agent phorbol-12-myristate-13-acetate (PMA). GM-CSF and IL-3 were measured by highly specific and sensitive immunoassays. Our findings showed that long-term cultured aHKc and HaCaT cells are capable of secreting GM-CSF but not IL-3 upon cytokine and PMA stimulation. Both interleukin-1 and tumor necrosis factor alpha, which are known to be present in human epidermis, particularly during cutaneous inflammatory processes, were found to stimulate GM-CSF release. Therefore, we conclude that increased GM-CSF levels may play an important role in the interactions between epidermal keratinocytes and blood cells in vivo.

Adult↗
PubMed1991

Induction and inhibition of NAD(P)H: quinone reductase in murine and human skin.

The purpose of this study was to characterize the human cutaneous NAD(P)H: quinone reductase (NQR) activity by known inhibitors of different reductases and to compare it with the murine skin and liver NQR activity. This enzyme plays a major role in the defence of cells against oxygen stress because it inhibits the 1-electron reduction of quinones to semiquinones and their subsequent oxidation to quinones termed as quinone redox cycle. It belongs to the aromatic hydrocarbon-responsive (Ah) battery. This gene battery includes Cyp1a1 (cytochrome P-450 IA1), Cyp1a2 (cytochrome P-450 IA2) and Nmo-1 [NAD(P)H: quinone reductase]. In the skin cytochrome P-450 IA1-dependent activity is about 1-5% compared to the corresponding activity in the liver, whereas NQR has the same activity in skin and liver. NQR was determined in the cytoplasm of murine skin, liver, and human keratinocytes using 2,6-dichlorophenolindophenol as the substrate. The Ah-receptor binding compounds, such as coal tar constituents, or 3-methylcholanthrene induce cytochrome P-450-dependent activities such as aryl hydrocarbon hydroxylase or 7-ethoxyresorufin-O-de-ethylase and NQR, whereas butyl hydroxytoluol, which does not bind to the Ah receptor, induces only NQR. For inhibition studies several known inhibitors of dihydrodiol dehydrogenase, aldo-keto and carbonyl reductase activities were used. There was a similar pattern of inhibition of the basal and induced activity in all tissues investigated. Pyrazole, progesterone and phenobarbital did not inhibit, whereas dicoumarol, rutin and indomethacin inhibited NQR activity in murine skin and liver as well as in human keratinocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Lactate dehydrogenase release as an indicator of dithranol-induced membrane injury in cultured human keratinocytes. A time profile study.

HaCaT cells, a rapidly multiplying human keratinocyte line, were tested for their sensitivity to antipsoriatic dithranol with regard to classical proliferation parameters and for the drug's action on the plasma membrane integrity by the dose- and time-dependent release of cytosolic lactate dehydrogenase (LDH). In the case of 3H thymidine as well as 14C amino acid incorporation the 50% inhibition concentration (IC50) was 0.2 microM dithranol 24 h after initial exposure to the drug. For protein content of attached cells the IC50 proved to be greater than 3.0 microM. Using 0.3, 1.0 and 3.0 microM dithranol, significant (p less than 0.05) dose dependent LDH release of 0.866 +/- 0.387, 1.842 +/- 1.127 and 2.938 +/- 1.635 mU per hour and cm2 confluent culture area was measured between the 5th and the 24th hour, compared to an acetone control of 0.504 +/- 0.299 mU/h x cm2. Between the 2nd and the 4th hour as well as from the 25th to the 48th hour and the 49th to the 72nd hour the LDH release after dithranol treatment did not exceed the control value. In accordance with these findings dose-dependent morphological signs of cell injury were detected by phase contrast microscopy beyond the 4th hour. The data reveal that: HaCaT cells are a very sensitive target for the antiproliferative action of dithranol; the drug causes considerable plasma membrane damage even at concentrations as low as 0.3 microM; and this membrane damage becomes evident after a latency of at least 4 h and for a limited period of up to 24 h.

Anthralin↗
PubMed1990

[Increased expression of proliferation keratins K 6 and K 16 in unaffected skin in exacerbated psoriasis].

The in vivo expression of the proliferation keratins K 6 and K 16 is characteristic for hyperproliferative diseases and positive in psoriatic lesions. Our study was performed in order to investigate the in vitro expression of proliferation keratins and to settle the question whether they are also inducible in organ cultures of uninvolved psoriatic skin, possibly differing from normal skin.

Adult↗
PubMed1990

[Cutaneous administration of liposomes--a review of the literature with special reference to findings from keratinocyte cultures, animal experiments and clinical studies].

Recent findings regarding the topical application of liposomes are reviewed under 3 headings: (1) keratinocyte cultures, (2) animal experiments, and (3) clinical studies. Under cell culturing conditions, liposomes are able to get into direct contact with living keratinocytes--just as in cutaneous application when the barrier of the horny layer is missing (i.e. in case of superficial skin defects or unkeratinized mucocutaneoaus surfaces). Under these circumstances, keratinocytes show liposomal alterations of the cell structure, proliferation, and lipid fluidity. Animal experiments and clinical studies have pointed out that, in comparison with a conventional formulation, a liposomal way of application can enhance the penetration of various substances as well as their toposelective enrichment in the skin, since the dermal-vascular absorption is diminished.

Animals↗
PubMed1990

[Tuberculosis cutis luposa gigantea with Mycobacterium bovis detection].

In an 80-year-old woman, retired farmworker, we observed lupus vulgaris extending over more than half of her leg. The extreme size of the affected area made us talk of a giant form in this case. Bacteriological investigation revealed Mycobacterium bovis. The minimal amount of tuberculin required to induce a positive intradermal reaction was 10 IU (GT Behring). Another case with similar dimensions (reported by Christiansen in 1967) had been caused by Mycobacterium avium and developed over a period of at least 5 years. The vast cutaneous affection of our patient, in contrast, had developed within only one year, starting from a brownish macula of the size of a palm on her upper leg. This macula - presumably the manifestation of quiescent lupus vulgaris - had not changed for more than 40 years. This late exacerbation of post-primary tuberculosis might have been favored by the patient's reduced immunologic resistance on account of her advanced age. In addition, local cofactors - namely ankylosis of her knee and contact eczematous dermatitis - have to be considered. In accordance with the resistogram, the disease responded to monotherapy with isoniazide.

Aged↗
PubMed1989

[Systemic photochemotherapy (PUVA) in acanthosis nigricans maligna: regression of keratosis, hyperpigmentation and pruritus].

We report on a 60-year-old patient, who developed malignant acanthosis nigricans (MAN) with intense itching 2 years after a large-cell bronchial carcinoma had been diagnosed and found inoperable. The MAN became manifest at a phase of full clinical remission of the lung tumor, which had been treated with cytostasis (cisplatin, vindesine), high energy irradiation, and extirpation of the lymph node metastases. One year after onset of MAN, the lung tumor relapsed, accompanied by an elevated serum level of carcinoembryonic antigen (CEA). The patient was slightly obese, but not diabetic. The generalized MAN was treated with 18 exposures to systemic PUVA (photochemotherapy) over 9 weeks. The patient received 8-methoxypsoralene (8-MOP) orally and a total UVA dose of 52 J/cm2; the last exposure amounted to a maximum dose of 4 J/cm2. Under this treatment, the patient was completely relieved from tormenting pruritus; in addition, we observed significant regression of the pigmented keratoses as well as the intertriginous maceration.

Acanthosis Nigricans↗
PubMed1989

Colorimetric growth assay for epidermal cell cultures by their crystal violet binding capacity.

The application of a simple, rapid, and inexpensive colorimetric growth assay was tested for human epidermal cells subcultured in uncoated plastic dishes. Cell layers were incubated with a crystal violet (CV) solution (0.2% with ethanol 2% in 0.5 M Tris-Cl buffer, pH 7.8) for 10 min at room temperature. After rinsing with 0.5 M Tris-Cl (pH 7.8) the cell layer was dried and decolorized with a sodium-dodecylsulfate solution (0.5% with ethanol 50% in 0.5 M Tris-Cl, pH 7.8) for 60 min at 37 degrees C. The extinction of the supernatant was read at the absorption maximum of 586 nm. The protein content of attached cells as classical parameter for quantifying cell growth was strongly related to CV extinction with a correlation coefficient of r = 0.98. Furthermore, the subcellular protein binding qualities of CV were analyzed. The water-soluble protein fraction of cultured epidermal cells was separated by sodium-dodecylsulfate polyacrylamide gel electrophoresis and stained with CV. We found a staining pattern which was qualitatively very similar to that of Coomassie blue, however less intense. Keratin electrophoresis revealed an affinity of CV to the 48, 50, and 56 kD cytokeratins. In conclusion, this CV assay is a reliable and simple method for the monitoring of epidermal cell growth in cultures.

Cell Division↗
PubMed1988

[Wound treatment with autogenous epidermal cell expansion culture].

Sheets of autologous epidermal cells grown by expansion culture were used to cover small skin defects in seven patients with postoperative necroses, necroses due to temporal arteritis, varicose ulcers or after tangential excision of tattoos. Several transplantation techniques were used: backing of the cultured epithelia with vaseline gauze, Surfasoft, Adaptic, Silastic foil, culturing directly from Petriperm-foil. Meshed Silastic-foil proved to give the best support. Optimal take of the in-vitro epithelia (more than 80% of their surface area) was achieved only for fresh dermal wound-beds. The take was only moderate on chronic granulation tissue, but the transplants reduced the formation of fibrinous-necrotic material and favoured the formation of fresh granulation tissue.

Adult↗
PubMed1987

[Transition to cutaneous squamous cell carcinoma in 2 patients with bowenoid papulomatosis].

We report on two female patients (30 and 33-year-old) suffering from bowenoid papulosis (BP) which showed HPV-16-DNA (E.-M. de Villiers, DKFZ, Heidelberg). Both patients developed cutaneous invasive squamous cell carcinoma in the perineal and vulvar region, resp. In the first patient, the microinvasive part of the tumor was excised. Subsequent therapy with interferon-gamma resulted in complete clinical and histological remission of the BP within 4 months; 6 months after discontinuation of the therapy with interferon, however, we observed a relapse of BP. In the second case, which showed more prominent BP alterations and deeper tumor invasion, interferon-gamma did not bring on any improvement within 3 weeks of therapy; thus radical operation was performed. To our knowledge, this is the first report on the transition of BP of the outer ano-genital region into invasive squamous cell carcinoma.

Adult↗