Polyamine conjugates of stigmasterol

Three new polyamine conjugates with stigmasterol [(3β,22E)-stigmasta-5,22-dien-3-ol] were synthesized and subjected to basic antimicrobial and cytotoxic tests. The conjugate derived from spermine, (3β,22E)-stigmasta-5,22-dien-3-yl 4(12-amino-4,9-diaza-dodecylamino)-4-oxobutanoate (5c), displayed considerable antimicrobial activity on Staphylococcus aureus at low concentration (50μgmL(-1)). The cytotoxic activity was tested on cells of human T-lymfoblastic leukemia (IC(50)=35.8±10.3μM (5c) and IC(50)=35.9±5.7μM (5b)) and normal human fibroblasts (IC(50)=38.0±2.8μM (5c) and IC(50)=45.5±1.9μM (5b)). Conjugate 5a displayed no activity in both tests.     

The possibilities and limitations of membrane methods for the histochemical demonstration of cholinesterases

Summary The thiocholine method for the histochemical detection of cholinesterases according to Karnovsky-Roots was adapted for unfixed cryostat sections by addition of the agar solution to the incubation mixture and by using the semipermeable membrane interposed between the section and the incubation medium. The procedure prevents the leakage of the enzyme activity of the section and is suitable for tissues where the cholinesterase activity is low.     

Alternate pathways of malonylCoA formation in Streptomyces aureofaciens

Alternate metabolic pathways for the formation of malonylCoA in the actinomycete Streptomyces aureofaciens are examined. Comparison of the specific activities of pyruvate kinase, pyruvate dehydrogenase, and phosphoenol-pyruvate carboxylase during cultivation, the degree of incorporation of individual radioactive substrates into the tetracycline molecule, and the high randomization of acetate-[2-¹⁴C], indicate that the malonylCoA used in tetracycline biosynthesis does not appear solely through the carboxylation of acetylCoA. The role of the phosphoenolpyruvate carboxylase and oxaloacetate dehydrogenase systems in the formation of malonylCoA is established, and using radio-GLC, a cell-free preparation of S. aureofaciens mycelium is shown to form malonate from oxaloacetate. The reaction requires HSCoA and NAD⁺.     

Ixodes ricinus tick saliva modulates tick-borne encephalitis virus infection of dendritic cells

Tick-borne encephalitis virus is an important human pathogen, naturally delivered into host skin via a tick bite. To examine the effects of the virus on dendritic cell biology, we cultured dendritic cells with two tick-borne encephalitis virus strains of different virulence in the presence of Ixodes ricinus tick saliva. Tick saliva treatment increased proportion of virus-infected cells, led to a decrease in virus-induced TNF-α and IL-6 production and to reduced virus-induced apoptosis. Our data indicate that tick saliva modulate virus-mediated alterations in dendritic cells, thus probably being involved in the early infection process in the host.