Advances in bioconversion of anthracycline antibiotics.

During the last decade new anthracycline-type structures with potential usefulness in cancer treatment have been supplied both by new microbial strains and by bioconversions of precursor molecules employing cells or enzymes. We highlight recent advances in bioconversion of anthracycline structures with the main focus on late transformations such as are carried out by oxidoreductases.

Complementarity of infrared linear dichroism and X-ray diffraction analysis as demonstrated by the study of a DNA-drug complex.

Infrared linear dichroism and X-ray diffraction analysis on oriented films and fibres, respectively, were used simultaneously to elucidate structural characteristics of a DNA-drug complex (the drug was the anticancer antibiotic violamycin BI, an anthracycline derivative). First, the parameters accessible by the two methods are briefly explained; then, attempts to inter-correlate the data from both lines of investigations are made, which demonstrate that they support and supplement each other favourably concerning several structural aspects. This holds, in particular, for results regarding the conformational flexibility of DNA in complexes and the relative amounts of intercalated and outside-bound drug molecules.

Age-dependent antileukemic action and suppression of immune response by 1,4-benzoquinone-guanylhydrazone-thiosemicarbazone (ambazone) in mice.

The antineoplastic activity of 1,4-benzoquinone-guanylhydrazone-thiosemicarbazone (ambazone) against murine leukemia P388 was found to be markedly reduced in 12- and 18-month-old mice as compared to young animals. The immune response against sheep red blood cells (SRBC), a T cell-dependent antigen, was also strongly diminished in tumor-free old mice and was further suppressed after ambazone treatment. Since the antileukemic effect of ambazone disappeared more or less in congenitally athymic nude mice, in neonatally thymectomized or silica-pretreated animals, it has been concluded that the action of the compound seems to be limited to young adult immunocompetent tumor-bearing hosts.

Progress in application of the image analysing system QUANTIMET 720 in the histomorphometry of the microcirculatory system.

The application of automated image analysing methods in the field of histomorphometry has been improved in the last decades. In this paper a new method is presented for the investigation of morphological reactions of the microcirculatory system. It is based on the measurement of quantitative changes in microvessel wall tissue by using the image analysing system QUANTIMET 720.

REP3-derived yeast shuttle vector.

A yeast-shuttle vector using a XbaI-PstI fragment of the 2 microns DNA 1293 bp in length has been constructed. This sequence spans the REP 3 locus and the origin of replication. Besides the 2 microns DNA derived sequences the resulting yeast shuttle vector contains the yeast LEU 2 gene and the Tet' gene of pBR 322.

Biological and biochemical activities of a toxoid of erythrogenic toxin type A.

A toxoid of erythrogenic toxin type A (ET A) was prepared by formaldehyde treatment. Already 15 min after exposure to formaldehyde in isoelectric focusing the ET A band at pH 5.2 shifted to a band at pH 4.

Localization and characterization of fibronectin-binding to group A streptococci. An electron microscopic study using protein-gold-complexes.

The location and nature of the binding sites for fibronectin (Fn) and its N-terminal 29 K fragment (FnF) on group A streptococci were studied by electron microscopy using these proteins labelled with colloidal gold. The investigated strains exhibited a different labelling intensity as well as a different labelling pattern varying from a strong regular distribution to a weak focal binding. Binding of Fn and FnF was inhibited by itself as well as by lipoteichoic acid (LTA), anti-LTA and concanavalin A.

Serum lipoprotein changes in female rats treated with progesterone or synthetic gestagens alone or in combination with estradiol. II. Serum triglycerides and hepatic triglyceride release.

The influence of progesterone (P) and synthetic gestagens given alone or in combination with estradiol (E2) on triglyceride (TG) concentration in serum of adult female rats was studied. Norethisterone acetate (NEA), levonorgestrel (LNG), dienogest (DEG), chlormadinone acetate (CMA) and P were administered orally at a dose of 10 mg/kg for three times. E2 was given chronically by s.

Serum lipoprotein changes in female rats treated with progesterone or synthetic gestagens alone or in combination with estradiol. I. Total and fractionated cholesterol and lipoprotein pattern.

In adult female rats, the effects of progesterone (P), norethisterone acetate (NEA), levonorgestrel (LNG), dienogest (DEG) and chlormadinone acetate (CMA) given alone at doses of 2.5 or 10 mg/kg p.o.

Tripartite streptokinase gene fusion vectors for gram-positive and gram-negative procaryotes.

A specific 1,596 bp HincII fragment ('skc) from the chromosome of Streptococcus equisimilis contains an active streptokinase (SK) gene (skc) lacking, in addition to the expression signals, codons 1 through 39 of wild-type skc but retaining the remainder of the skc coding sequence together with the transcription terminator. Using this fragment as an indicator gene, we constructed two types of vectors which in appropriate hosts resulted in the synthesis of SK fusion proteins after insertional activation of 'skc. The first type are open reading frame (ORF) vectors in which 'skc was inserted into pUC18 out of frame with respect to lacZ', thus conferring an SK-negative phenotype.

Mass spectral studies of the carboxylic acid ionophore antibiotic griseochelin and its derivatives.

The electron impact (EI) mass spectra (75 eV) of the new carboxylic acid ionophore griseochelin and some of its derivatives are discussed. The mass spectral fragmentation was studied using exact mass measurements and deuterium labelling. Furthermore, the negative ion mass spectra (2-4 eV) of these compounds are compared with their EI mass spectra.

Formation of double-walled microtubules and multilayered tubulin sheets by basic proteins.

Some basic proteins enable microtubule protein to form special assembly products in vitro, known as double-walled microtubules. Using histones (H1, core histones) as well as the human encephalitogenic protein to induce the formation of double-walled microtubules, we made the following electron microscopic observations: (1) Double-walled microtubules consist of an "inner" microtubule which is covered by electron-dense material, apparently formed from the basic protein, and by a second tubulin wall. (2) The tubulin of the second wall seems to be arranged as protofilaments, surrounding the inner microtubule in a helical or ring-like manner.

Pharmacokinetics of 14C-ambazone in rats.

In rats, the pharmacokinetics of 14C-ambazone after i.v. and oral administration was studied.

Type 1 and 3 M-proteins of Streptococcus pyogenes: peptic extraction and fibrinogen binding properties.

The pepsin extraction of group A type 1 streptococci for the isolation of M protein fragments was studied at different pH values and at different time intervals. The extracts were compared by SDS PAGE and fused rocket immunoelectrophoresis. Type 1 M protein fragments were prepared in preparative scale by pepsin extraction of type 1 streptococci at pH 5.

Expression of env sequences of the bovine leukemia virus (BLV) in the yeast Saccharomyces cerevisiae.

DNA sequences of the envelope (env) gene of the bovine leukemia virus (BLV) were expressed in the yeast Saccharomyces cerevisiae. Two yeast promoters, the repressible PHO5 promoter and the constitutive PGK promoter, were used to construct four expression plasmids comprising either a sequence of the surface antigen gp51 or a (gp51 + gp30) sequence. The expressed heterologous gene products were characterized by Western blot analysis and competitive radioimmunoassay.

Biological characterization of three new spontaneous mouse lymphomas and comparison with the leukemia P388.

Three spontaneous lymphomas of 23- to 24-month-old (AB/Jena X DBA/2 Jena)F1 females were serially transplanted into syngeneic hosts. They were histologically classified as malignant lymphoblastic lymphomas (ABDt2 and ABDt5) and as a malignant lymphoma of histiocytic type (ABDt6). All lymphomas disseminated into the liver, spleen, and pancreas, whereas ABDt2 and ABDt5 additionally infiltrated the bone marrow and leptomeninx.

Distribution of 14C-ambazone in normal and leukemia P 388-bearing mice.

There is some evidence in the literature that the pharmacokinetics of anticancer agents can be influenced by the presence of a tumor. Therefore several authors recommend pharmacokinetic studies of such drugs to be performed also in tumor-bearing animals (2, 5, 7). The aim of the present study was to evaluate the influence of different stages and routes of inoculation of leukemia P 388 in B6D2F1-hybrid mice on the tissue distribution of ambazone, a new potential antineoplastic drug.

Carcinogenesis and aging. VIII. Effect of host age on tumour growth, metastatic potential, and chemotherapeutic sensitivity to 1.4-benzoquinone-guanylhydrazonethiosemicarbazone (ambazone) and 5-fluorouracil in mice and rats.

Mice and rats of various ages (3, 10-12, and 18-19 months) were inoculated with the transplantation tumours murine melanoma B16 (B16), mammary adenocarcinoma 755 (Ca-755), leukemia P388 (P388), and rat rhabdomyosarcoma RA-2 (RA-2). Subcutaneous (sc) growth of B16 was not markedly affected by the age of the syngeneic host whereas intravenously (iv) inoculated 12 months old C57BL/6 mice developed more pulmonary metastases than animals 3 months of age. Median survival time (MST) of 18 months old mice bearing Ca-755 was significantly shorter than that of younger individuals.

Use of alternative dose schedules for the determination of sublethal doses of potential antiviral drugs in mice.

In mice the ratio between maximally tolerated sublethal doses (MTD) after single and repeated administration of benzoxazolyl-2-formyl-S-ethyl-isothiosemicarbazone (ZIMET 111/74) was found to be different after s.c., p.

Nonconventional yeasts: their genetics and biotechnological applications.

To date, more than 500 species of yeasts have been described. Most of the genetic and biochemical studies have, however, been carried out with Saccharomyces cerevisiae. Although a considerable amount of knowledge has been accumulated on fundamental processes and biotechnological applications of this industrially important yeast, the large variety of other yeast genera and species may offer various advantages for experimental study as well as for product formation in biotechnology.

Analysis of the nourseothricin-resistance gene (nat) of Streptomyces noursei.

A gene (nat) conferring resistance to the streptothricin antibiotic nourseothricin (Nc) was cloned from the producer Streptomyces noursei into Streptomyces lividans on the vector pIJ702 to form pNAT1. The nat gene was localized on a 1-kb SalI-MboI fragment, which also carries the nat promoter. Divergent promoter activity from the nat promoter region was identified on the cloned fragment using promoter probe plasmids pIJ486 and pIJ487.

Xylose catabolism by a mutant ofStreptomyces chrysomallus altered in the regulation of D-glucose isomerase.

A mutant ofS. chrysomallus with a D-glucose isomerase inducible by D-glucose or its catabolites was characterized. In contrast to the wild-type strain it showed a decreased catabolite repression by D-glucose of D-xylose consumption and a constitutive pentose phosphate pathway as well.

Use of chemostat for selection ofStreptomyces chrysomallus mutants altered in the induction of D-glucose isomerase.

D-glucose isomerase ofStreptomyces chrysomallus PL45 is inducible by D-xylose only. In mutants obtained by means of a selection procedure in a chemostat the isomerase was induced in xylose-free medium containing glucose as carbon source.

Inhibitors of the cleavage of aclacinomycins.

The reductive cleavage of the aclacinomycins A (I), Y (II), and B (III) by intact mycelia or subcellular fractions of the producer strain S. spec. AM 33352/F43 is suppressed in the presence of uncouplers, complex-forming agents, detergents, and some metal anions such as chromate.