Antimicrobial and antiviral activities of an actinomycete (Streptomyces sp.) isolated from a Brazilian tropical forest soil

A promising producer of bioactive compounds isolated from a Brazilian tropical soil was tested for its range of antimicrobial activities. Strain 606, classified as Streptomyces sp., could not be identified up to species level, suggesting a possible new taxon. The supernatant and 10 extracts and fractions, obtained by extraction and chromatographic techniques, presented antimicrobial activity using antibiograms. The methanolic fraction was highly active against pathogenic bacteria, phytopathogenic fungi and the human pathogenic yeast Candida albicans. It also possessed high antiviral activity inhibiting the propagation of an acyclovir-resistant herpes simplex virus type 1 strain on HEp-2 cells at non-cytotoxic concentration. The strong cytotoxic effect suggests an antitumour action. This revised version was published online in August 2006 with corrections to the Cover Date.     

Reversing the detrimental effect of adriamycin on skin grafts in rats

We evaluated in a rat model the effects of a homologous fibrin glue in reversing the effects of Adriamycin on adherence and take of skin grafts. A total of 40 male Fisher rats were used in the study. During the first phase of the experiment, the animals were assigned to either group I (N = 10) receiving normal saline or group II (N = 10) receiving 6 mg/kg Adriamycin by tail vein injection 24 hours before surgery. Skin grafts with and without fibrin glue were placed over wounds in the backs of the animals and adherence was measured at 24 and 48 hours. In the second phase (N = 20), the experiment was repeated, this time evaluating the total area of skin graft take at 7 days. Fibrin glue was found to increase adherence and take of skin grafts in all Adriamycin-treated animals.     

Nitroso-aldicarb induces sister-chromatid exchanges in human lymphocytes in vitro

Nitroso-aldicarb was tested for its ability to induce sister-chromatid exchanges (SCE) and cell-cycle delay in human peripheral blood lymphocytes in vitro. This derivative of aldicarb induced a dose-dependent increase in SCE values per cell. In addition, a slight decrease in the successive mitotic progression of cells in culture was observed.     

Effects of various compounds on growth of yeast cells of Histoplasma capsulatum

Summary A number of compounds were screened for their effects on growth of the yeast cells ofHistoplasma capsulatum. Included were penicillin and related compounds, sulfhydryl inhibitors, various organic sulfur compounds recently synthesized for the first time, and compounds structurally related to the required metabolites, thiamine and cystine or cysteine. Cephalothin was the only one of the penicillin related compounds which inhibited growth. This occurred only when a high concentration (8.3 × 10^–4 M) was used. Of the analogues of cystine tested, allylglycine had the greatest inhibitory effect on growth of the yeast cells in the synthetic medium, but it failed to inhibit growth in a complex medium containing peptones and plasma. Among the sulfhydryl inhibitors, the maleimides were the most effective, producing complete inhibition of growth in the peptone medium at 10µg/ml or less. At subinhibitory concentrations the cultures tended to become mycelial. The action of the maleimides was reversed by cystine over a range of concentrations. At low concentrations, some of the disulfide derivatives of thiamine stimulated growth equally as well as thiamine, but at concentrations of 100 to 150µg/ml, they completely inhibited growth. On the basis of results obtained to date, three classes of the new organic sulfur compounds being tested offer promise as sources of potentially useful chemotherapeutic agents. These classes, which differ widely in structure, are as follows: the benzyl decylaminoethyl disulfides, the acyl disulfides, and the trithiopercarbamates.This investigation was supported by Public Health Service Research Grant AI-03524 from the National Institute of Allergy and Infectious Diseases.     

Human pluripotent stem cell-derived extracellular vesicles: From now to the future

Extracellular vesicles (EVs) are nanometric particles that enclose cell-derived bioactive molecules in a lipid bilayer and serve as intercellular communication tools. Accordingly, in various biological contexts, EVs are reported to engage in immune modulation, senescence, and cell proliferation and differentiation. Therefore, EVs could be key elements for potential off-the-shelf cell-free therapy. Little has been studied regarding EVs derived from human pluripotent stem cells (hPSC-EVs), even though hPSCs offer good opportunities for induction of tissue regeneration and unlimited proliferative ability. In this review article, we provide an overview of studies using hPSC-EVs, focusing on identifying the conditions in which the cells are cultivated for the isolation of EVs, how they are characterized, and applications already demonstrated. The topics reported in this article highlight the incipient status of the studies in the field and the significance of hPSC-EVs’ prospective applications as PSC-derived cell-free therapy products.     

Micro-buffy coats of whole blood: a method for the electron microscopic study of mononuclear cells

A method for the electron microscopic study of human peripheral lymphocytes by which very small buffy coats are obtained through centrifugation of heparinized whole blood in glass or plastic microhematocrit tubes is presented. This method is time saving and efficient, yielding well preserved material and a comparatively large number of mononuclear cells (mainly lymphocytes) in each thin section.