Ventilator associated pneumonia and infection control

Rifampicin, an important drug in the treatment of tuberculosis, is used extensively despite its broad effects on drug-drug interactions, creating serious problems. The clinical importance of such interactions includes autoinduction leading to suboptimal or failed treatment. The concomitantly administered effects of rifampicin on other drugs can result in their altered metabolism or transportation that are metabolised by cytochromes P450 or transported by p-glycoprotein in the gastrointestinal tract and liver. This review paper summarises recent findings with emphases on the molecular mechanisms used to explain these broad drug-drug interactions. In general, rifampicin can act on a pattern: rifampicin activates the nuclear pregnane X receptor that in turn affects cytochromes P450, glucuronosyltransferases and p-glycoprotein activities. This pattern of action may explain many of the rifampicin inducing drug-drug interactions. However, effects through other mechanisms have also been reported and these make any explanation of such drug-drug interactions more complex.     

The distribution of Zn65 in the cotyledons ofVicia faba and its translocation during the growth and maturation of the plant

Summary The uptake of Zn⁶⁵ by seeds ofVicia faba, soaked in a Zn⁶⁵Cl₂ solution and maintained within the experimental condition described in the text, was constant and did not depend on the amount of the radionuclide given. However, the percentage of the total absorbed Zn⁶⁵ retained by seed coats varied according to the cultural variety ofVicia faba. Most of the Zn⁶⁵ entering the seed, remained bound to the seed coat, the remainder entered the embryo and cotyledons and was concentrated around the abaxial part of this latter, lessening towards the adaxial region. The fate of the isotope was followed in all stage of plant development. Its distribution was represented as counts per minute per unit mass (dry) of plant tissue, and on a percentage basis. In general, zinc decreased in the main root acropetally then increased at the root stem transition zone, decreased again in the first internode than increased acropetally towards the apex of the stem. Anthers had the highest counts per unit mass compared to other plant organs, including the rest of the flower. Zn⁶⁵ distribution calculated on a percentage basis increased in that order: Roots, stem, leaves in one month old plants and older. These observations held also in plants grown from —Zn medium and from seeds to which radioactive zinc was introduced before and during the formation of their pods. Water-soluble Zn⁶⁵ was also investigated in different plant's organs. Some of these results are compared and discussed with those previously obtained using a histochemical method.     

New and effective entrapment of polyelectrolyte-enzyme-complexes in LentiKats

Amyloglucosidase EC 3.2.1.3 was used as model for the immobilisation of enzymes in poly(vinylalcohol) hydrogel (LentiKats) lenses. The entrapment of the enzyme in PVA-hydrogel based on a two-step procedure, firstly its coupling to polyelectrolytes increased the structure level of the enzyme, and subsequently, the resulting complex was entrapped in LentiKats. The immobilised enzyme retained 45% of its original activity and lost no activity over five repeated batch runs.     

Dual hydrolysis model of the slowly biodegradable substrate in activated sludge systems

Experimental assessment of the hydrolysis rate coefficients for both domestic sewage and a number of industrial wastewaters was performed with emphasis on two different hydrolysis mechanisms associated with the readily and slowly hydrolyzable COD fractions. The adopted dual hydrolysis model was justified on the basis of significantly different rate constants. The hydrolysis rate of particulate COD occurred at such a slow rate that would significantly interfere with endogenous decay. © Rapid Science Ltd. 1998