Bioavailability of fine dispersed platinum as emitted from automotive catalytic converters: a model study.

Automobile exhaust catalytic converters emit fine dispersed elemental platinum, Pt (0), in the nanometer range coated on larger aluminium oxide carrier particles. A pre-requisite for a potential systemic toxic effect of the emitted platinum is its bioavailability which was investigated using laboratory animals. To this end, a model substance was synthesised which consisted of aluminium oxide particles < or = 5 microns onto which platinum particles > or = 4 nm were deposited by a calcination process. These particles closely resemble those emitted from automobile exhaust converters. This model substance was applied to female Lewis rats in two doses by intratracheal instillation; the animals were killed after 1, 7, 28 and 90 days. In addition, the model substance was also applied during a 90-day inhalation study. After microwave digestion of the tissues, the platinum was determined in all organs and body fluids by inductively coupled plasma/mass spectrometry (ICP/MS). Platinum was found in the blood, urine and faeces and all important organs (liver, spleen, kidneys, adrenals, stomach, femur). Based on the platinum content determined in the body fluids and all organs (except the lung and the faeces) it was calculated that up to 16% of the platinum was retained in the lung 1 day after intratracheal instillation and up to 30% of the fine dispersed platinum deposited on an average during 90 days inhalation in the lung was bioavailable. Using size exclusion chromatography (SEC) in combination with ICP/MS, it was shown that > or = 90% of the bioavailable platinum was bound to high molecular weight compounds (approximately 80-800 kDa), most likely proteins.     

New,Non‐quinone Fluorogeldanamycin Derivatives Strongly Inhibit Hsp90

Streptomyces hygroscopicus is a natural producer of geldanamycin. Mutasynthetic supplementation of an AHBA‐blocked mutant with all possible monofluoro 3‐aminobenzoic acids provided new fluorogeldanamycins. These showed strong antiproliferative activity and inhibitory effects on human heat shock protein Hsp90. Binding to Hsp90 in the low nanomolar range was determined from molecular modelling, AFM analysis and by calorimetric studies.     

Mitochondrial Associated Yeast Flocculation ‐The Effect of Acetylsalicylic Acid

Mitochondrial function is generally accepted as important for expression of yeast flocculation. In this study, a correlation between mitochondrial activity and flocculation is demonstrated using the XTT reduction assay. The mitochondrial activity of strongly flocculent cells was higher than those of weakly flocculent cells and cells cultivated in the presence of acetylsalicylic acid. Furthermore, we show the first oxylipin‐containing flocculation binding sites on yeast cell surfaces using scanning electron microscopy. We propose that in addition to zymolectin‐mediated flocculation, oxylipin interactions may also play a role in yeast flocculation.     

Relating consumer preferences to sensory and physicochemical properties of dry beans (Phaseolus vulgaris)

BACKGROUND: Dry beans (Phaseolus vulgaris) have a range of varieties, colours and sizes. Differences in physicochemical and sensory properties influence consumer choices for beans. This study related consumer preferences to sensory and physico‐chemical properties of selected bean varieties—Jenny, Kranskop, PAN 148, AC Calmont, PAN 150 and Mkuzi—grown in Mpumalanga (MP) and Free State (FS) in South Africa. RESULTS: Significant (P < 0.05) variety, location as well as location × variety interaction effects were found for both physico‐chemical and sensory properties of beans. Jenny‐FS, Mkuzi and PAN 148‐MP beans had relatively long cooking times (>60 min). Some beans (e.g. PAN 150 and Mkuzi beans) were described as bitter, soapy and metallic with a raw‐bean flavour whereas more preferred beans (e.g. Jenny‐MP, Kranskop‐MP) were sweet, soft and with a cooked‐bean flavour. CONCLUSION Apart from small seed size, sensory characteristics such as bitter taste, soapy and metallic mouthfeel and hard texture contributed to consumers' dislike of certain bean varieties. The sweet taste, cooked‐bean flavours, soft and mushy textures of the most accepted varieties seemed to be related to beans with good hydration capacities that facilitated softening during cooking. Copyright © 2007 Society of Chemical Industry     

The determination of inorganic sulphate in serum and synovial fluid by high performance ion chromatography

A method for the determination of inorganic sulphate based on high performance ion chromatography is presented. The separation was performed on an anion-exchange column with a 1.8 mmol/l sodium carbonate/ 1.7 mmol/l sodium hydrogen carbonate-buffer, pH 10.35. Conductivity of the eluate was monitored after suppression of the background conductivity caused by the eluent-buffer. Serum and synovial fluid samples were prepared by ultrafiltration through membranes with a molecular mass cutoff of M(r) 10,000. The viscosity of the synovial fluids was reduced by treatment with hyaluronate lyase before ultrafiltration. The method showed a linear response for sulphate concentrations between 0.5 and 1000 mumol/l. The limit of detection was 1 mumol/l for aqueous standards. For serum the coefficient of variation within-run was 2.3%-2.4%, the coefficient of variation between days 2.9%-3.1%. For synovial fluids the coefficient of variation within-run was 3.1%-3.4%, the coefficient of variation between days 4.6%-5.7%. Standard recovery experiments performed by spiking pools of human sera containing low sulphate concentrations with sulphate concentrations between 5 mumol/l and 40 mumol/l showed recoveries between 98.9% and 100.6%. The corresponding experiments with pools of synovial fluids showed recoveries of 98.3% to 100.9%. As determined from 127 serum samples the reference range for sulphate was 262 mumol/l-420 mumol/l, with a mean value of 314 mumol/l. No dependence on age or sex was observed. The sulphate concentration in 36 synovial fluids from knees affected by inflammatory processes showed a mean value of 424 mumol/l and a standard deviation of 70 mumol/l. In 41 synovial fluids from knees affected by chronic degeneration joint disease, the sulphate concentrations were statistically significantly lower, with a mean of 374 mumol/l and a standard deviation of 58 mumol/l. The concentrations of sulphate in the synovial fluids were statistically significantly higher than those in the serum samples used for determination of the reference range. Following the oral application of a subtoxic single dose of acetaminophen (32.5 mg/kg body weight-62.5 mg/kg body weight) to 4 healthy volunteers, there was a significant decrease in the concentration of sulphate in serum with a minimum at 4-5 h after application of the drug. The cumulative concentration decrease of sulphate in serum and the kinetic constant of the sulphate depletion were not correlated with the applied acetaminophen dose normalized for body weight.     

Cost-Effective Deployment of Bandwidth Partitioning in Broadband Networks

We consider the issue of bandwidth partitioning in a multi-rate broadband network. Requests for a number of different types of connection are offered to the network. For the purposes of connection admission and resource allocation, we assume that it is possible to allocate an effective bandwidth to a single connection of each type. The network manager has the problem of implementing an admission control scheme to maximise the profit earned from the network. Our focus here is the extent to which it is a good idea to partition the bandwidth on the physical links to form reserved end-to-end logical links corresponding to the origin–destination pairs. It is clear that implementation of such partitioning will lead to a loss of multiplexing opportunities. However, in a network with end-to-end logical links, costs related to overhead such as route selection, admission control and signalling may be much reduced. This effect may outweigh the loss of revenue due to missing out on multiplexing opportunities. We investigate the nature of this trade-off, by designing optimal or near-optimal partitioned networks using efficient algorithms for finding routes and allocating bandwidth to end-to-end logical links on a fixed underlying physical network. We then calculate the net rate of earning profit under each of the schemes as a function of the ratio of overhead costs to call revenue. Our conclusion is that it is cost-effective to partition bandwidth under a variety of realistic assumptions about revenue rates and overhead costs.     

Prevalence of primary acquired melanosis and nevi of the conjunctiva and uvea in the dysplastic nevus syndrome. A case-control study

PURPOSE: To investigate whether conjunctival and uveal nevi and primary acquired melanosis are more common in individuals with the dysplastic nevus syndrome than in control subjects derived from the general population. METHODS: Power calculations were used to determine the sample size. After invitation, 162 individuals with the dysplastic nevus syndrome and 119 control subjects, matched for sex and age but otherwise randomized from the Stockholm county census file, were entered into the study. All individuals were examined in a masked fashion by the same ophthalmologist, and the presence of conjunctival and uveal melanocytic lesions and the iris color, skin type, and hair color of each individual were recorded. Contingency tables and odds ratios were used for statistical evaluation. RESULTS: The proportions of individuals with the dysplastic nevus syndrome featuring primary acquired melanosis of the conjunctiva, or nevi of the iris and choroid were not significantly different from those of control subjects. However, individuals with the dysplastic nevus syndrome appeared to have a more sun-sensitive skin type and a reddish or blond hair color more often than control subjects. CONCLUSION: In contrast to previous reports, this study suggests that ocular melanocytic lesions are no more common in individuals with the dysplastic nevus syndrome than in the general population. Therefore, this work does not provide support that periodic ophthalmic surveillance of individuals with the dysplastic nevus syndrome for the purpose of detecting conjunctival or uveal melanomas, or their precursors, is meaningful.     

Standardized ultrasound examination for evaluation of instability of the acromioclavicular joint

Anteroposterior X-ray views of both acromioclavicular (AC) joints with 10-kg weights held in each hand are the generally accepted procedure for diagnosis of Tossy I-III grades of AC joint separation. An analogous diagnosis can be made by standardized ultrasound examination. Ten individuals with Tossy-I, 11 with Tossy-II and 8 with Tossy-III instability were examined both radiographically and by B-mode ultrasound. The degree of AC joint separation was uniformly determined on the basis of a calculated index (AC Index = AC joint width of uninjured side/AC joint width of injured side). The mean AC Index for Tossy-I instability determined by ultrasound was 1.0; mean indices of 0.49 and 0.5 were determined for Tossy-II injury by ultrasound and X-ray, respectively, and of 0.21 and 0.2, respectively, for Tossy-III instability. Statistical analysis showed significant differences between the mean AC indices of all three groups (P < 0.0001). We conclude that the reliability of ultrasound examination of AC joint instability is equal to that of radiographic measurement. Standard X-rays of the shoulder remain mandatory only to exclude fracture. The indication for operative stabilization of the AC joint can be established on the basis of the grade of AC joint instability measured by the side-effect-free and cost-effective method of ultrasound examination (AC Index < 0.3 equivalent to Tossy-III instability).