Choosing the number of images and image position when analyzing the UNC Passive Aerosol Sampler for occupational exposure assessment.

The University of North Carolina passive aerosol sampler (UNC sampler) could be an alternative when measuring occupational dust exposure, but the time required for microscopic imaging of the sampler needs to be reduced to make it more attractive. The aims of this study were to (1) characterize the effect on precision when reducing imaging, in order to shorten analysis time and (2) assess if the position of the images makes a difference. Eighty-eight samplers were deployed in different locations of an open pit mine. Sixty images were captured for each UNC sampler, covering 51% of its collection surface, using scanning electron microscopy. Bootstrapped samples were generated with different image combinations, to assess the within-sampler coefficient of variation (CVws) for different numbers of images. In addition, the particle concentration relative to the distance from the center of the sampler was studied. Reducing the number of images collected from the UNC sampler led to up to 8.3% CVws for 10 images when calculating respirable fraction. As the overall CV has previously been assessed to 36%, the additional contribution becomes minimal, increasing the overall CV to 37%. The mean concentrations of the images were modestly related to distance from the center of the sampler. The CVws changed from 8.26% to 8.13% for 10 images when applying rules for the image collection based on distance. Thus, the benefit of these rules on the precision is small and the images can therefore be chosen at random. In conclusion, reducing the number of images analyzed from 60 to 10, corresponding to a reduction of the imaged sampling area from 51% to 8.5%, results in a negligible loss in precision for respirable fraction dust measurements in occupational environments.

Inhibition of gastric H+/K+-ATPase by substituted imidazo[1,2-a]pyridines.

A hydrophobic imidazopyridine, SCH 28080 (3-cyanomethyl-2-methyl-8-phenylmethoxy)imidazo[1,2-a]pyridine) has previously been shown to inhibit gastric acid secretion in vivo and in vitro. Studies of isolated gastric H+/K+-ATPase have demonstrated that SCH 28080 reversibly inhibited the enzyme and competitively interacted with the K+-stimulated ATPase and p-nitrophenylphosphatase activities of the H+/K+-ATPase. To elucidate the mechanism of inhibition further, for example to establish whether the inhibitor interaction occurs on the luminal or the cytosolic side of the enzyme or if compound pKa influences inhibition, SCH 28080 and three analogues have been studied. We have examined the effects on K+-stimulated ATPase activity in isolated ion-permeable membrane vesicles at different pH values and KCl concentrations. In ion-tight membrane fractions the effect on acid formation was estimated. The results are in agreement with the hypothesis that the protonated, and thus positively charged, form of SCH 28080 is the active species, and that the inhibitory effect is exerted by binding of the compound to the luminal side of the H+/K+-ATPase.

Antiulcer agents. 5. Inhibition of gastric H+/K(+)-ATPase by substituted imidazo[1,2-a]pyridines and related analogues and its implication in modeling the high affinity potassium ion binding site of the gastric proton pump enzyme.

A number of substituted imidazo[1,2-a]pyridines and related analogues were selected for biochemical characterization in vitro against both the purified gastric proton pump enzyme, H+/K(+)-ATPase, and the intact gastric gland. The inhibitory activity in these two in vitro models was then examined for correlation with the gastric antisecretory potency determined for these compounds in vivo by using the histamine-stimulated Heidenhain pouch dog. Analysis of the biological data suggested that the inhibitory activity of the analogues determined in two in vitro models is predictive of their in vivo gastric antisecretory activity following intravenous, but not oral, administration. Furthermore, the good correlation observed between the in vitro and in vivo models suggests that these compounds are gastric proton pump inhibitors in vivo. A molecular modeling study of these compounds using the active analogue approach has defined the molecular volume which is shared by the active analogues, as well as the molecular volume which is common to the inactive analogues. Graphical representation of the difference between these molecular volumes can be interpreted in terms of a hypothetical description of the pharmacophore by means of which 3-(cyanomethyl)-2-methyl-8-(phenylmethoxy)imidazo[1,2-a]pyridine, Sch 28080 (1) and its analogues interact with the gastric proton pump enzyme, H+/K(+)-ATPase.

Radiographic joint space narrowing and histologic changes in a rabbit meniscectomy model of early knee osteoarthrosis.

The purpose of this study was to compare weightbearing radiographs with histologic cartilage evaluation in a rabbit meniscectomy model of the early stage of osteoarthrosis. Fifteen rabbits had a medial meniscectomy performed in one knee and a sham operation in the other knee. Five rabbits each were sacrificed at 13, 25, and 40 weeks after surgery. Radiographic joint space width and histologic cartilage changes of the medial knee compartment were quantified. Five non-operated knees and five knees in which the meniscus had been removed immediately before the evaluations served as control specimens. Overall, the joint space of the peripheral part of the medial knee compartment was narrower in knees operated on for meniscus removal than in sham-operated knees (P < 0.003). In the knees with the meniscus removed, more cartilage changes were seen at the joint surface area of contact on radiographs than in the sham-operated knees (P < 0.0015). Indeed, the area of contact had cartilage changes similar to those in the whole medial compartment. However, there was no correlation between the degree of histologic cartilage change and the corresponding joint space measurements. Joint space width as measured on weightbearing radiographs is reduced after meniscectomy in the rabbit, but it does not reflect the degree of cartilage damage of the loaded joint surfaces in early stages of osteoarthrosis.

Evaluation of applanation resonator sensors for intra-ocular pressure measurement: results from clinical and in vitro studies.

Glaucoma is an eye disease that, in its most common form, is characterised by high intra-ocular pressure (IOP), reduced visual field and optic nerve damage. For diagnostic purposes and for follow-up after treatment, it is important to have simple and reliable methods for measuring IOP. Recently, an applanation resonator sensor (ARS) for measuring IOP was introduced and evaluated using an in vitro pig-eye model. In the present study, the first clinical evaluation of the same probe has been carried out, with experiments in vivo on human eyes. There was a low but significant correlation between IOP(ARS) and the IOP measured with a Goldmann applanation tonometer (r = 0.40, p = 0.001, n = 72). However, off-centre positioning of the sensor against the cornea caused a non-negligible source of error. The sensor probe was redesigned to have a spherical, instead of flat, contact surface against the eye and was evaluated in the in vitro model. The new probe showed reduced sensitivity to off-centre positioning, with a decrease in relative deviation from 89% to 11% (1 mm radius). For normalised data, linear regression between IOP(ARS) and direct IOP measurement in the vitreous chamber showed a correlation of r = 0.97 (p < 0.001, n = 108) and a standard deviation for the residuals of SD < or = 2.18 mm Hg (n = 108). It was concluded that a spherical contact surface should be preferred and that further development towards a clinical instrument should focus on probe design and signal analysis.

An image analysis method for prostate tissue classification: preliminary validation with resonance sensor data.

Resonance sensor systems have been shown to be able to distinguish between cancerous and normal prostate tissue, in vitro. The aim of this study was to improve the accuracy of the tissue determination, to simplify the tissue classification process with computerized morphometrical analysis, to decrease the risk of human errors, and to reduce the processing time. In this article we present our newly developed computerized classification method based on image analysis. In relation to earlier resonance sensor studies we increased the number of normal prostate tissue classes into stroma, epithelial tissue, lumen and stones. The linearity between the impression depth and tissue classes was calculated using multiple linear regression (R(2) = 0.68, n = 109, p < 0.001) and partial least squares (R(2) = 0.55, n = 109, p < 0.001). Thus it can be concluded that there existed a linear relationship between the impression depth and the tissue classes. The new image analysis method was easy to handle and decreased the classification time by 80%.

Contamination of irrigation solutions in an operating theatre.

Sterile irrigation solution, used in open systems in a conventional orthopedic operating theatre, were examined for bacterial contamination. At the end of 13 of 21 operations (duration greater than or equal to one hour) the solution tested displayed the growth of Staphylococcus epidermidis and/or diphtheroid rods and/or other species. It is concluded that irrigation by solutions, kept in open bowls during an operation, is a potential source of contamination.