Glutathione conjugation of chlorobenzylidene malononitriles in vitro and the biotransformation to mercapturic acids in rats

The glutathione conjugation of 2-chloro-, 3-chloro-, 4-chloro- and 2,6-dichlorobenzylidene malononitrile (chloroBMNs) was investigated in vitro. In incubation mixtures containing rat liver cytosol (9000 g), the decrease in the initial amount of glutathione due to the various chloroBMNs ranged from 40 to 60% and occurred both enzymatically and spontaneously at physiological conditions (37°C, pH7.4). 2,6-DichloroBMN, however, depleted glutathione largely spontaneously (38±3%). The steric hindrance of the two chlorosubstituents probably plays an important role during the glutathione-S-transferase catalyzed reaction.The hydrolysis of the chloroBMNs to the corresponding chlorobenzaldehydes and malononitrile was studied in a mixture of buffer pH 7.4 and ethanol. The rate of hydrolysis of 2,6-dichloroBMN was slower than those of the related chloroBMNs. This means that 2,6-dichloroBMN will be the most stable compound in the presence of water.Only IP administration of 2-chloroBMN (CS) to adult male Wistar rats gave enhancement of urinary thioether excretion. A thioether could be isolated and was identified as the N-acetyl-S-[2-chlorobenzyl]-L-cysteine. The quantity of this benzylmercapturic acid in the urine of rats amounted to 4.4% dose (0.07 mmol/kg, n=12).After IP administration of 2-chloro- and 3-chlorobenzaldehyde to rats benzylmercapturic acid excretion in the urine was found to be 7.6 and 1.1% of the dose, respectively. Administration of the related 4-chloro- and 2,6-dichlorobenzaldehyde, however, resulted in _no urinary mercapturic acid excretion.It is very likely that in rats the initial biotransformation of chloroBMNs is mainly hydrolysis to corresponding chlorobenzaldehydes, leading in the case of 3-chloro-, 4-chloro- and 2,6-dichloroBMN to no mercapturic acid excretion in the urine.Nevertheless, 2,6-dichloroBMN will be the most reactive compound with proteins and therefore the best haptene in comparison with the related chloroBMNs.This work was financially supported by a grant from the Dutch Foundation for Medical Research FUNGO, grant no. 13-28-57     

Some practical notes on documentation of superficial hyperthermia treatment.

A detailed and accurate documentation of the treatment setup of each individual hyperthermia session is extremely important for retrospective data analysis as well as treatment quality control. In this paper the relatively simple and cheap documentation system developed by the Hyperthermia Department of the Dr Daniel den Hoed Cancer Center, is presented.     

In-vitro sensitivity of Hodgkin's disease to hydrogen peroxide toxicity. Correlation with peroxidase activity

Hodgkin's disease of nodular sclerosis and mixed cellularity subtypes contains numerous eosinophils and substantial amounts of extracellular eosinophil peroxidase (EPO). To determine if the extracellular EPO retains cytotoxic activity, the authors analyzed cells from 13 cases of Hodgkin's disease and ten cases of benign lymphoid hyperplasia for their in vitro sensitivity to killing by a low concentration of hydrogen peroxide. Cells from cases of benign lymphoid hyperplasia (0.5% +/- 1% killing) and lymphocyte predominant Hodgkin's disease (4.5% +/- 6% killing) were significantly (P less than 0.05) less sensitive to killing by hydrogen peroxide than cells from nodular sclerosis Hodgkin's disease (26% +/- 13% killing) and mixed cellularity Hodgkin's disease (52% +/- 9% killing). The authors concluded that cells from Hodgkin's disease of nodular sclerosis and mixed cellularity subtypes have an increased sensitivity to killing by an otherwise nonlethal concentration of hydrogen peroxide.     

Characteristics of wheeze during histamine-induced airways obstruction in children with asthma.

BACKGROUND--An automated system has been developed for the detection of sound patterns suggestive of airways obstruction in long term recordings. The first step, presented here, was tracheal sound recording during histamine-induced airways obstruction. METHODS--The tracheal sounds of 29 children aged 8-19 years with asthma were recorded during airways obstruction caused by histamine inhalation using a system for continuous respiratory telemetry and computer analysis. Sound patterns were analysed, classified, and related to airways obstruction measured by lung function tests based on the forced expiratory volume in one second (FEV1). RESULTS--Five sound patterns were identified, one dominant sensitive and four specific to a fall in FEV1 of > 20%. The presence of at least one of three specific sound patterns during unforced respiration predicted a fall in FEV1 of > 20% in 87.5% of the subjects. The inspiratory and expiratory sound patterns were almost equally informative of airways obstruction. CONCLUSIONS--Wheezes can be differentiated with more precision than is currently accepted. Tracheal sound patterns are sensitive and specific predictors of histamine-induced airways obstruction. These patterns are neither invariably nor proportionally related to the results of lung function testing. However, they can be used for detection of airways obstruction on the basis of their presence or absence.     

Effects of T cycles of light/darkness and periodic forced activity on methamphetamine-induced rhythms in intact and SCN-lesioned rats: explanation by an hourglass-clock model

In this study intact and suprachiasmatic nuclei (SCN)-lesioned female rats were treated with chronic methamphetamine (MA) via the drinking water. Body temperature, feeding, drinking and wheel-running activity were continuously and automatically recorded. The rats were subjected to light-dark (LD) cycles with period T = 23 hr for 4 months and subsequently T = 25 hr for 3 months. Daily 3-hr forced activity (FA 3:21) was imposed during a few weeks under both LD regimes. MA induced infradian rhythms (period tau s = 28-54 hr) that were found to run parallel in all functions. In intact rats these infradian rhythms showed relative coordination by the LD regime and tau s shortened when T lengthened. In SCN-lesioned rats, however, the infradian rhythms were independent of the LD regime. Under the FA cycles tau s lengthening as well as synchronization was observed. We hypothesized that the MA-induced rhythms reflect a long-period sleep-wake cycle of the hourglass type. We investigated this hypothesis with a modified version of the hourglass-clock model of sleep regulation. Computer simulations showed that this model might offer an explanation for the experimental observations.     

Incorporation and washout of orally administered n-3 fatty acid ethyl esters in different plasma lipid fractions

The aim of the present study was to quantify the incorporation of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) into plasma lipids after oral administration of n-3 fatty acid ethyl esters, since little is known about the rate and pattern of incorporation into plasma lipid fractions. In addition, we aimed to obtain preliminary information regarding EPA half-life, which is needed to establish an optimal dosing schedule. Five healthy volunteers ingested two 8.5 g doses of n-3 fatty acid ethyl esters daily for 7 d, supplying 6.0 g EPA/d and 5.3 g DHA/d. The fatty acid compositions of plasma phospholipids (PL), cholesteryl esters (CE) and triacylglycerols (TAG) were determined during supplementation and during a washout period of 7 d. Half-lives of EPA and DHA were calculated. The proportion of EPA in PL showed a 15-fold increase after 7 d (P < 0.001), while DHA showed a smaller increase (P < 0.01). In CE, EPA also increased (P < 0.05), while DHA did not increase at all. Remarkably, incorporation of DHA into TAG was even higher than that of EPA. Half-life of EPA in PL ranged from 1.63 to 2.31 d (mean 1.97 (SE 0.15) d), whereas mean half-life of EPA in CE was 3.27 (SE 0.56) d. In three subjects, washout of EPA and DHA from TAG seemed to follow a bi-exponential pattern, with a short half-life (< 1 d) in the initial phase and a half-life of several days in the second phase. In conclusion, EPA ethyl esters are rapidly incorporated into plasma lipids, especially into PL. The relatively long half-life of EPA in plasma would permit a dosing schedule with intervals of > or = 12 h in supplementation studies.     

A new surgical technique for deep stromal, anterior lamellar keratoplasty

AIMS: To describe a new surgical technique for deep stromal anterior lamellar keratoplasty. METHODS: In eye bank eyes and sighted human eyes, aqueous was exchanged by air, to visualise the posterior corneal surface--that is, the "air to endothelium" interface. Through a 5.0 mm scleral incision, a deep stromal pocket was created across the cornea, using the air to endothelium interface as a reference plane for dissection depth. The pocket was filled with viscoelastic, and an anterior corneal lamella was excised. A full thickness donor button was sutured into the recipient bed after stripping its Descemet's membrane. RESULTS: In 25 consecutive human eye bank eyes, a 12% microperforation rate was found. Corneal dissection depth averaged 95.4% (SD 2.7%). Six patient eyes had uneventful surgeries; in a seventh eye, perforation of the lamellar bed occurred. All transplants cleared. Central pachymetry ranged from 0.62 to 0.73 mm. CONCLUSION: With this technique a deep stromal anterior lamellar keratoplasty can be performed with the donor to recipient interface just anterior to the posterior corneal surface. The technique has the advantage that the dissection can be completed in the event of inadvertent microperforation, or that the procedure can be aborted to perform a planned penetrating keratoplasty.     

Considerations on the EU definition of a nanomaterial: Science to support policy making

In recent years, an increasing number of applications and products containing or using nanomaterials have become available. This has raised concerns that some of these materials may introduce new risks for humans or the environment. A clear definition to discriminate nanomaterials from other materials is prerequisite to include provisions for nanomaterials in legislation. In October 2011 the European Commission published the ‘Recommendation on the definition of a nanomaterial’, primarily intended to provide unambiguous criteria to identify materials for which special regulatory provisions might apply, but also to promote consistency on the interpretation of the term ‘nanomaterial’. In this paper, the current status of various regulatory frameworks of the European Union with regard to nanomaterials is described, and major issues relevant for regulation of nanomaterials are discussed. This will contribute to better understanding the implications of the choices policy makers have to make in further regulation of nanomaterials. Potential issues that need to be addressed and areas of research in which science can contribute are indicated. These issues include awareness on situations in which nano-related risks may occur for materials that fall outside the definition, guidance and further development of measurement techniques, and dealing with changes during the life cycle.