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J Geisel

Publications and source records attributed to J Geisel.

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

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

Rapid diagnosis of familial defective apolipoprotein B-100.

A method is described for the rapid, economic and non-radioactive examination of DNA samples from hypercholesterolaemic patients for familial defective apolipoprotein B-100, using a modified polymerase chain reaction (PCR) protocol and restriction enzyme isoform genotyping. Because of the high prevalence of familial defective apolipoprotein B-100, which is estimated to be one in 500 in most screened general populations, interest is focussed on a simple method for detection of this point mutation. In our protocol a diagnostic restriction site is created by PCR, using a specifically designed partly mismatched primer. In the case of familial defective apolipoprotein B-100 the amplified DNA segment contains an additional ScaI site, whereas DNA amplified from the normal allele is resistant to ScaI digestion. A rapid differentiation between the two alleles is achieved by agarose gel electrophoresis of the ScaI-digested PCR product.

Apolipoprotein B-100↗
PubMed1990

[HMG-CoA reductase inhibitors in familial hypercholesterolemia. Therapy with simvastatin alone and in combination with cholestyramine in low dosage; a report of 2 years experiences].

We have studied the effect of simvastatin, an inhibitor of the rate-limiting enzyme in cholesterol biosynthesis, alone and in combination with cholestyramine in 48 patients. Simvastatin 40 mg decreased total serum cholesterol, LDL cholesterol and apolipoprotein B by 35%, 40% and 35%, respectively, while HDL cholesterol and apolipoprotein A-I increased by 10% (p less than 0.01) and 7% (p less than 0.05), respectively. The addition of 8 g cholestyramine caused a further decrease in total cholesterol and LDL cholesterol to a total of 42% and 49%, respectively. Eighteen of the 48 patients have now been under combined treatment for 2 years. The initial high decreases in total cholesterol and LDL cholesterol were stabilized for the whole period. Some patients developed gastrointestinal complaints, which made necessary a reduction of simvastatin in two cases. Biochemical side effects (e.g. increases in CK and transaminases) were not observed.

Adult↗
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↗
PubMed1988

A new Apa LI restriction fragment length polymorphism in the low density lipoprotein receptor gene.

The existence of a new Apa LI restriction fragment length polymorphism in the third intron of the low density lipoprotein (LDL) receptor gene was described. As a gene probe we used a newly constructed derivative of pLDLR 3 which did not contain the highly repetitive Alu-sequences in exon 18. This new gene probe detected all exon sequences containing restriction fragments, and enabled us to demonstrate all described polymorphisms, which might be useful for genetic linkage studies. Based on analysis of 72 unrelated normo- and hypercholesterolaemic persons, the frequency of the allele A2, which showed the additional cutting site, was determined to be 0.05. With the simplified gene probe, pLDLR delta, we also studied other polymorphisms. A clear linkage disequilibrium between the Pvu II and Msp I polymorphisms was detected. This, and the previously described linkage disequilibrium of the two Msp I polymorphisms, demonstrate that the LDL receptor gene is apparently less heterogeneous than expected from the number of described polymorphisms.

Alleles↗