Social isolation modifies the response of mice to experimental Mengo virus infection.

To investigate the effects of social isolation on host resistance male mice were housed either individually (IH) or in groups of four or five (GH). All animals were infected with MengoM,L virus. Incubation time (INCUB), duration of illness (ILL), death rate (DR), histopathological changes, and serum corticosterone levels (CORT) were recorded.

Bioconversion of steroids by Cochliobolus lunatus--II. 11 beta-hydroxylation of 17 alpha, 21-dihydroxypregna-1,4-diene-3,20-dione 17-acetate in dependence of the inducer structure.

The 11 beta-hydroxylase of the filamentous fungus Cochliobolus lunatus m 118 was induced with the substrate 17 alpha, 21-dihydroxypregna-1,4-diene-3,20-dione 17-acetate (11 beta-deoxyprednisolone 17-acetate) itself, substrate analogues, different pregnane compounds, sterols, intermediates of microbial sterol side-chain degradation or bile acids, together with 24 different steroids in a standardized test system. The resulting 11 beta-hydroxylation rate, leading to prednisolone 17-acetate and prednisolone, respectively, was determined and compared with the hydroxylation rate of non-induced cultures. The transformation yield strongly depended on the inducer structure.

Zero interaction response surfaces, interaction functions and difference response surfaces for combinations of biologically active agents.

In the field of combination experiments there is wide-spread confusion over definitions, terminology and methods for the evaluation of interaction between biologically active agents. According to our view the widely used isobole approach is the method of choice. In this contribution it is shown how the combination of the classical isobole approach with response surface modeling and computer graphics leads to powerful new methods for the assessment of interaction of biologically active agents.

Steroid-1-dehydrogenase of Rhodococcus erythropolis: purification and N-terminal amino acid sequence.

The inducible steroid-1-dehydrogenase from the bacterium Rhodococcus erythropolis IMET 7030 was purified to homogeneity using affinity chromatographic, electrophoretic, and ion exchange techniques. The spectrum of the pure enzyme is characterized by the associated FAD. The M(r) of the enzyme is 56,000.

Effect of cis-diaminedichloroplatinum (II) (cis-DDP) on the intracellular Na+/K(+)-ratio in K 562 leukemia cells as revealed by X-ray microanalysis.

Changes of intracellular ionic homeostasis are believed to play a role in the cytostatic action of cis-DDP. It has been observed by means of X-ray microanalysis that cis-DDP did not alter the intracellular Na+/K(+)-ratio of K 562 leukemia cells during incubation periods which lasted shorter than the average doubling time of the cells of nearly 15 h. After 24 h the treated cells displayed at least two main populations in the distribution histogram of the Na+/K(+)-ratio.

The characterization of two new low molecular weight proteins (LMPs) from Streptococcus pyogenes.

Two novel extracellular mitogenic substances were isolated from Streptococcus pyogenes strain NY-5 and characterized. The purification steps involved an initial enrichment of the proteins from culture supernatant by silica gel adsorption, followed by ion exchange chromatography and gel filtration. The purified materials were homogeneous in SDS-PAGE, showed estimated molecular weights of 12 kD and isoelectric points of 4.

In vivo changes of heterogeneity of mouse peritoneal macrophages induced by cis-diamminedichloroplatinum (II) (cis-DDP) and related platinum compounds.

The s.c. injection of cis-DDP into ABD2F1 mice (8 mg/kg b.

Localization of the cholesterol oxidase in Rhodococcus erythropolis IMET 7185 studied by immunoelectron microscopy.

Rhodococcus erythropolis IMET 7185 produces an inducible cholesterol oxidase (COD) which can easily be extracted by treatment of cells with 0.1% Triton X-100. The yield of the enzyme was 3.

The formation of A-DNA in NaDNA films is suppressed by netropsin.

Oriented films of NaDNA complexed with netropsin were studied with deuterium nuclear magnetic resonance (2H NMR), X-ray diffraction and ultraviolet (UV) linear dichroism to obtain information about the influence of netropsin on the structural arrangement of the DNA bases and on the B-A transition. The results of these studies clearly demonstrate a strong suppression of the formation of A-DNA at relative humidities (RHs) down to about 50%. The suppression was complete in the NaDNA-netropsin complex studied with 2H NMR which had a netropsin input ratio, r, of 0.

Fluorenone-azomethines, a novel class of microtubule inhibitors that specifically affect cell proliferation.

The effects of various azomethine derivatives on microtubule (MT) assembly in vitro as well as on cell proliferation, cell shape, and the cytoskeleton of some cultured murine cell lines were studied. 3 of them, the alpha-diphenylene-N-(p-[bis-(beta-hydroxyethyl)-amino]-phenyl)-nit rone (DHPN), alpha-diphenylene-N-(p-[N-(hydroxyethyl)-N-(gamma-hydroxypropyl)- amino]-phenyl)-nitrone, and alpha-diphenylene-N-(p-diethylaminophenyl)-nitrone, strongly inhibit the assembly of microtubules (MTs) in vitro (50% inhibition at 4 to 7 mumol/l). The same compounds are also able to disrupt preformed microtubules.

Cholinergic and adrenergic drugs affect delayed type hypersensitivity in C57BL/6 mice.

The present study examined the influence of systemic administration of neuroactive drugs on delayed-type hypersensitivity (DTH) in C57BL/6 mice. The cholinergic agonist nicotine and the acetylcholinesterase inhibitor physostigmine decreased DTH, whereas the alpha-adrenergic agonist clonidine stimulated DTH. In contrast isoprenaline, a specific beta-adrenergic agonist suppressed DTH.

Overexpression of a Rhodococcus erythropolis protein in Escherichia coli with immunological identity to the Rhodococcus steroid 1-dehydrogenase. Immunoelectron microscopic localization and electrophoretic studies.

The recombinant Escherichia coli K-12 strain chi 6060 harbouring the plasmid pYA 1201 with a gene from Rhodococcus erythropolis IMET 7030 overexpressed a protein which reacts with a monospecific antiserum against the steroid 1-dehydrogenase (Sdh) from the same Rhodococcus strain. It was shown previously that this recombinant protein exhibits no enzymatic activity. By immunogold labelling the protein was localized on ultrathin sections of the recombinant E.

Scarlet fever and types of erythrogenic toxins produced by the infecting streptococcal strains.

Group A streptococcal strains were isolated from the throats of 46 children suffering from scarlet fever. For detection of erythrogenic toxins (ETs), the culture supernatants were concentrated 100 times by ethanol precipitation and solubilisation in acetate buffer. ELISA was used to identify ETA and double immunodiffusion to identify ETB and ETC.

DNA-bending on ligand binding; change of DNA persistence length.

This paper simulates the helix-characteristic changes of apparent DNA persistence length caused by randomly distributed helix bends as induced, e.g., by DNA-bound ligand molecules.

Protein A-streptokinase fusion protein for immunodetection of specific IgG antibodies.

The streptococcal streptokinase gene truncated at its 5' end was fused to regions of the staphylococcal protein A gene encoding the Fc-binding domains A and B. The resultant fusion gene, when expressed in the Escherichia coli lacPO system or under the speA expression/secretion signals in S. sanguis, specified a bifunctional hybrid protein, SPA-SKC, capable of Fc binding and plasminogen activation.

A simple ELISA procedure for HIV-1 based on the enzyme beta-lactamase.

The enzyme beta-lactamase (penicillin-amido-beta-lactam-hydrolase, EC 3.5.2.

High-cell-density cultivation of Escherichia coli.

High-cell-density cultivations of Escherichia coli in glucose-mineral-salt media produce more than 100 g dry cells litre-1 in special fed-batch modes with feeding of glucose and ammonia only. The specific growth rate can be adjusted to allow optimum recombinant protein generation.

Synergistic cytotoxicity of human recombinant tumour necrosis factor alpha combined with microtubule effectors.

Combinations of human recombinant tumour necrosis factor alpha (rhTNF alpha) with each of four different agents disturbing the microtubule system of the cellular cytoskeleton were tested for synergistic cytotoxic action against murine melanoma B16K and L-M(S) cells. In addition to the known microtubule effectors colchicine, vincristine, and taxol, the influence of the fluorenone-azo-methine derivative alpha-diphenylene-N-(p-[bis-(beta-hydroxyethyl-amino]-phenyl)- nitrone (DHPN) on the rhTNF alpha cytotoxicity was studied. Applying a novel computer-based isobole method [Suehnel J (1990) Antiviral Res 13:23-40] concentration ranges of synergistic, zero, and antagonistic interaction were found after in vitro combination of rhTNF alpha with each of the drugs tested in a 72-h cytotoxicity assay.

Age-dependent experimental tumor dissemination of murine melanoma B16.

Female C57BL/6 Jena mice, 3-, 12-, and 18-month-old, were inoculated intravenously (i.v.) with syngeneic melanoma B16 cells.

Can coated vesicles bind directly to microtubules?

Using an ultrathin-sectioning electron microscopic procedure, no efficient binding of coated vesicles to microtubules (both purified from brain tissue) could be achieved, independently of the presence of microtubule-associated proteins. Addition of the ATP analogue AMP-PNP or the inorganic tripolyphosphate, known to cause tight associations of (uncoated) vesicles to microtubules by means of specific motor proteins, could not enhance the binding efficiency. Moreover, crude preparations of clathrin, the major protein of the coat, did not affect the turbidity course of microtubule assembly.

Measuring of the in-vitro assembly of microtubules by dynamic light scattering.

The kinetics of in-vitro assembly of microtubule protein (MTP) to microtubules (MTs) was followed under various conditions (temperature, GTP, ultrasonic treatment) by dynamic light scattering (DLS) and turbidimetric measurements. The results of both methods roughly coincide, but DLS additionally allows to differentiate between MTs and aggregates and to follow their growth. The complexity of these investigations, however, causes serious restrictions in the interpretation of the DLS data.

The microtubule system and the reduplication of microtubule organizing centres in Dictyostelium discoideum.

The microtubule system of normal and microtubule-poisoned amoebae of Dictyostelium discoideum has been investigated both by indirect immunofluorescence with antibodies to microtubule proteins and electron microscopy. Nocodazole, like some other microtubule poisons, destroys most of the microtubules in both interphase and dividing cells resulting in an inhibition of nuclear and cell division. The microtubule organizing centres, however, continue to duplicate once or twice.