A fluorescent aptasensor with product-triggered amplification by exonuclease III digestion for highly sensitive ATP detection

An improved sensitivity of an ATP detection assay was achieved by using an allosteric probe and exonuclease III digestion product-triggered signal amplification.

Reductive dechlorination of BCl3 for efficient ammonia borane regeneration

Chemical regeneration of ammonia borane (AB) from its digestion product of H2-depleted AB, BCl3, has been implemented based on reduction and ammoniation reactions.

Determination of Trace Silver in Water Samples by Online Column Preconcentration Flame Atomic Absorption Spectrometry Using Termite Digestion Product

A new method for Ag determination in water samples using solid phase extraction (SPE) coupled to a flow injection system and flame atomic absorption spectrometry was developed. The sorbent used for Ag preconcentration and extraction was the termite digestion product. Flow and chemical variables of the system were optimized through a multivariate procedure. The factors selected were adsorbent mass, buffer type and concentration, sample pH, and sample flow rate. The detection limit and precision were 3.4 μg L−1and 3.8% (n=6, 15 μg L−1), respectively. The enrichment factor and the linear working range were, respectively, 21 and 10–50 μg L−1. Results for recovery tests using different water samples were between 96 and 107%. The proposed methodology was applied with success for the determination of Ag in water used to wash clothes impregnated with silver nanoparticles, supplied by a factory located in Santa Catarina, Brazil.

Assay of proteinases of psychrotrophic bacteria in milk using Hide Powder Azure and a simple procedure for clarification of milk

SummaryThe clarification of milk by addition of solutions of Triton X-100 and EDTA after digestion of added Hide Powder Azure (HPA) was found to provide a simple method of determining the extracellular proteinase activity of Gram-negative psychrotrophic bacteria in pasteurized whole milk. The light absorbance of the clarified HPA digestion product was measured directly, after a brief incubation period, and was stable to storage of samples in diffuse daylight for at least 2 d. Proteinase produced by growth in refrigerated whole milk of as few as 2·5 × 106cfu ml−1ofPseudomonas fluorescensAR11 was detected.

Monooctanoin Use for Gallstone Dissolution

Monooctanoin (Capmul 8210), a digestion product of medium chain triglycerides, is a cholesterol solvent that has been used for the dissolution of retained cholesterol gallstones following cholecystectomy. Bile duct infusion of monooctanoin is associated with little toxicity, although potentially serious problems can result from absorption of the drug or tissue infiltration. Gastrointestinal side effects such as anorexia, nausea, vomiting, diarrhea, and abdominal pain have been reported most commonly. Complete gallstone dissolution has occurred in ∼50–75 percent of patients receiving monooctanoin. Although mechanical stone removal is still considered to be the treatment of choice for retained gallstones, monooctanoin use appears promising for stone dissolution in patients in whom mechanical removal has been unsuccessful or is impossible.

The fate of homologous 125I-labelled immunoglobulin G within rat visceral yolk sacs incubated in vitro

When 125I-labelled rat IgG (immunoglobulin G) is incubated in vitro with visceral yolk sacs from 17.5-day-pregnant rats, the protein is readily degraded. The major radioactive digestion product that accumulates in the medium is [125I]iodo-L-tyrosine. When rotenone (10 microM) is also present in the incubation medium, the rate of digestion of IgG is inhibited to the same extent as the rate of pinocytosis of 125I-labelled polyvinylpyrrolidone. Proteolysis is likewise inhibited when either NH4Cl (30 mM) or leupeptin (30 micrograms/ml) is present in the medium. The above findings strongly suggest that the observed proteolysis occurs within lysosomes. Normally, yolk sacs that have been exposed in vitro to radiolabelled substrates release radioactivity slowly when the tissue is re-incubated, unless the substrate can be degraded within lysosomes and released in the form of low-molecular-weight hydrolysis products. However, in such experiments 125I-labelled rat IgG shows quite exceptional behaviour in being rapidly released in an apparently intact form (as well as being degraded). If an agent that inhibits pinocytosis (e.g. rotenone or 2,4-dinitrophenol) is present in the incubation medium during exposure of the tissue to 125I-labelled rat IgG, it abolishes release of macromolecular radioactivity on re-incubation of the tissue. Enhanced tissue accumulation of 125I-labelled rat IgG, induced by the presence of leupeptin in the medium during the uptake phase, resulted in no concomitant increase in the amount of 125I-labelled IgG released in macromolecular form on re-incubation of the tissue. These findings indicate that the observed rapid release of 125I-labelled IgG is unlikely to represent release from lysosomes and is more compatible with release from a separate class of vesicle that does not fuse with lysosomes.

Dark field EM of the RNA of the small subunit of the E. coli ribosome

We have embarked on a series of EM experiments using the dark field mode in an attempt to ascertain how much of a role the ribonucleic acid (RNA) component of the ribosome has in determining the structure of the protein-nucleic acid complex. We have observed that treatment of specimens of the smaller subunit enhances the visibility of band-like structures on the "back" of the subunit. In total, though not necessarily all appearing at once on a single individual, three parallel bands of 20 Å diameter are seen (Fig. 2). We have speculated that these are double stranded sections of the RNA that emerge on the surface. This does not preclude external single stranded sections that are not as prominent, however. The identification of the bands with double stranded external RNA is still subject to further testing. In a very recent experiment we have examined a heated RNAase digestion product that has been shown to lack a section of its RNA.