Pharmacotherapy of Amanita phalloides poisoning using silybin

A total of 18 cases of Amanita phalloides poisoning was treated by combined chemotherapy during 1980 and 1981. After attempted primary elimination of the toxin all patients received silybin as basic therapy mainly by infusion and, in two instances, silymarin orally. In order to investigate the effect of silybin therapy a retrospective study of the followed-up case records was made. The cases were arbitrarily classified into three groups of severity (light, medium and severe) according to clinical and laboratory findings. A close relationship was found between the severity of the intoxication and the time elapsed before commencement of silybin therapy. The time interval between mushroom intake and the commencement of the silybin administration averaged 71.5 hours in the "severe" group compared with 46 and 33.8 hours, respectively, in the "medium" and "light" groups. The mean silybin dosage was 33 mg/kg body weight/day; the mean duration of silybin therapy was 81.6 hours. With the exception of one fatality in a particularly high dosage suicidal intoxication, all patients survived. Administration of silybin within about 48 hours after mushroom intake seems to be an effective measure to prevent severe liver damage in Amanita phalloides poisoning.     

Characterization of a binding factor that interacts with the sequences upstream of the vaccinia virus thymidine kinase gene

A small 176 base-pair cloned DNA fragment, representing the nucleotide sequences proximal to the 5-end of the vaccinia virus thymidine kinase (VV TK) gene, was radiolabeled and used in concert with gel retention assays to detect, partially purify, and characterize a promoter binding factor (PBF) extracted from vaccinia virions. The VV TK PBF was purified from solubilized virus particles by a combination of ion-exchange and DNA-affinity chromatographic procedures. The interaction between VV TK PBF and VV TK promoter sequences was relatively specific in that binding to the radiolabeled probe could be effectively inhibited by unlabeled VV TK promoter or VV TK promoter-specific oligonucleotides, but not by similar-sized fragments of control plasmid DNA. The VV TK PBF did, however, bind to other VV early-promoter elements. Glycerol gradient sedimentation provided an estimate of 130–140 kD for the native molecular weight of VV PBF. This correlated well with data from the purification of VV PBF from radiolabeled VV particles that revealed 2 polypeptides, with molecular weights of 70 and 68 kD that co-purified with VV TK PBF activity. Taken together, these results suggest that a heterodimeric promoter-binding factor, which is present within the cytoplasm of VV-infected cells, is capable of specifically interacting with VV early-promoter elements.     

Location by paper chromatography of compensatory ovarian hypertrophy (COH) inhibiting activity in acetic acid extracts from bovine pineals

Summary Acetic acid extracts of bovine pineals and cerebral cortex were separated on Sephadex G-25 columns. Subsequently two low molecular weight fractions, F₂ and F₃, were ultrafiltered through the membranes UM2 and UM05. The UM05 residues were gel filtered on Sephadex G-15 columns or chromatographed on Dowex W50-X4 columns. Fractions from these columns were tested and those which showed COH-inhibiting activity were separated by preparative paper chromatography in different solvents. The absorption spectra of those fractions were recorded and tested for COH-inhibition. By these methods, a COH-inhibitor was localized in three different solvents. Some active paper chromatography fractions were studied in high pressure, reverse phase, liquid chromatography. This latter method showed that the active fractions obtained by paper chromatography contain several orthophthalaldehyde (OPT) positive compounds.This work was supported by NIH Grant no. HD 08759.     

Melanotropic peptide receptors: membrane markers of human melanoma cells

Abstract The objectives of this research were to determine whether melanotropin receptors are characteristic (constant) membrane markers of human melanoma cells. Methodologies were developed to visualize these receptors by fluorescence microscopy. Multiple copies (10–20) of both [Nle⁴.D-Phe⁷]α-MSH, a superpotent analog of α-melanocyte stimulating hormone (α-MSH). and a fluorophore, were conjugated to polyvinyl alcohol (PVA). Incubation in the presence of the multivalent macromolecular conjugate (FITC-PVA-MSH) resulted in binding of human epidermal melanocytes and keratinocytes and human melanoma cells (both melanotic and amelanotic) to the fluorescent conjugate. Binding of the conjugate to the cells exhibited a unique cluster pattern (capping) suggesting a receptor internalization related phenomenon. Most importantly, every cell of every melanoma cell line, melanotic or amelanotic. possessed receptors as visualized by fluorescence microscopy. Since the cells were not synchronized, some binding apparently took place during all phases of the cell cycle. Therefore, receptor expression appears not to be cell-cycle dependent. Specificity of binding of FITC-PVA-MSH was demonstrated by several studies, (i) Binding of the conjugate to melanoma cells could be blocked by prior incubation of the cells in the presence of the unconjugated hormone analog: [Nle⁴,D-Phe⁷]α-MSH. (ii) The macromolecular conjugate lacking bound ligand (FITC-PVA) did not bind to the melanoma cells, (iii) Another peptide, a substance-P analog, attached to the substrate (FITC-PVA-SP) failed to bind to the cells, (iv) With the exception of keratinocytes, other cells of nonmelanocyte origin (e.g., fibroblasts, spleen, liver, kidney cells, and mammary cancer cells, lung cancer cells) did not bind to the conjugate. Thus, cell-specific melanotropin receptors appear to be characteristic cell surface markers of epidermal melanocytes, keratinocytes, and melanoma cells. In several human melanoma cell lines these receptors appeared to be functional since [Nle⁴,α-Phe⁷]α-MSH stimulated tyrosinase activity. Fluorescent melanotropin conjugates might prove useful in determining whether all human melanoma (primary and metastatic) tumors possess such receptors. These receptors might then provide targets for melanotropic peptides for the identification, localization, and chemotherapy of melanoma.     

Studies in vitro with ICI 174,864, [D-Pen2, D-Pen5]-enkephalin (DPDPE) and [D-Ala2, NMePhe4, Gly-ol]-enkephalin (DAGO)

The interactions of a proposed, selective delta receptor antagonist (ICI 174,864) and selective agonists at mu and delta receptors, [D-Ala2, NMePhe4, Gly-ol]-enkephalin (DAGO) and [D-Pen2, D-Pen5]-enkephalin (DPDPE), respectively, have been studied using the electrically-stimulated mouse isolated vas deferens (MVD) and the guinea-pig isolated ileum (GPI). Incubation of increasing concentrations of ICI 174,864 (10,30,100 and 300 nM) produced a dose-related and parallel rightward displacement of the DPDPE dose-response curve in the MVD. In contrast, ICI 174,864 (300-3000 nM) failed to affect the DAGO dose-response curve in the same tissue. Analysis of the DPDPE-ICI 174,864 interaction in the MVD using the pA2 method revealed a Schild plot slope of -0.68 suggesting the involvement of more than one population of receptors. ICI 174,864 (300 nM) failed to antagonize DPDPE in the GPI at doses up to 30 microM. These results suggest that (a) ICI 174,864 acts as a selective delta antagonist in the MVD; (b) DPDPE interacts with mu receptors in the MVD but only at very high concentrations, and (c) delta receptors appear not to be of functional importance in the GPI.