Silicone elastomer microshards in fluid from a painful metatarsophalangeal implant site. A case report

Histopathologic studies have demonstrated microshards from silicone elastomer metatarsophalangeal joint implants in adjacent tissues in a setting of chronic inflammation and in inguinal lymph nodes. Cytologic smears of synovial fluid from symptomatic implanted joints should show these refractile, nonpolarizing microshards in the reactive inflammatory context. Nonspecific enzymatic inflammatory activity contributes to further destabilization of the implants, eventuating in symptoms and signs requiring prosthesis removal. Cytopathologic examination of aspirated fluid from the vicinity of a symptomatic implanted joint demonstrates foreign body reaction to silicone elastomer, predicting a need for intervention before the local damage is severe and disabling.     

The role of attention in feature detection and conjunction discrimination: an electrophysiological analysis

An electrophysiological probe technique was used to ascertain whether the same attentional mechanisms are employed for both the detection of simple visual features and the discrimination of conjunctions of features. Visual search arrays containing 14 grey items and 2 colored items were presented; one color was designated relevant for each trial block. Subjects were required to report the presence or absence of the relevant color (feature detection condition) or the shape of the relevantly-colored item (conjunction discrimination condition). Shortly after the onset of the search array, a task-irrelevant probe stimulus was flashed at the location of the relevant or irrelevant color and the event-related potential (ERP) produced by this stimulus was used to assess sensory processing at the probed location. Probes presented at the location of the relevant color were found to elicit enhanced ERP components and probes presented on the opposite side of the display from the relevant color elicited suppressed components. These effects were observed in both the detection and discrimination conditions, indicating that spatially restricted attentional processes are used for both the detection of simple features and the discrimination of conjunctions. However, one ERP component (the PI wave) exhibited these effects in the discrimination condition but not in the detection condition, indicating that conjunction discrimination utilizes additional attentional processes beyond those required for feature detection.     

Chronic effects of smokeless tobacco extract on rat liver histopathology and production of HSP-90

Tobacco consumption is a worldwide problem. The recent increase in the consumption of the smokeless tobacco products (snuff and chewing tobacco) has stimulated interest into the carcinogenic effects of these forms of tobacco. The use of smokeless tobacco products has increased in popularity as the use of cigarettes has become less socially acceptable. For most individuals the use of tobacco is a chronic process. Therefore, the effects of an aqueous extract of smokeless tobacco (STE) in rats following low-dose exposure were examined. Female Sprague-Dawley rats were treated orally with 25 mg STE/kg every other day for 90 days. In order to obtain information regarding the cytotoxicity of STE, the ultrastructural changes occurring in livers of rats following administration of STE were examined under light and electron microscopy. Electron microscopy revealed that in the perisinusoidal spaces an accumulation of indistinct filamentous material occurred following 60 days of treatment, occupying most of the sinusoids. Moreover, the lipids were in a state of disintegration. Significant increases in 90 kDa protein expression were also observed due to chronic treatment with STE. Western blot analysis using a polyclonal mouse antibody against heat shock/stress protein 90 (HSP90) confirmed that the overexpressed proteins were heat shock/stress proteins (HSPs). The HSPs are believed to serve as adaptive or survival functions involving a rapid but transient reprogramming of cellular metabolic activity to protect cells from oxidative damage.     

Screen‐printed biosensor for allergens

Allergen levels in indoor environments, leading to many diseases, eg asthma, rhinitis and conjunctivitis, affect a large and increasing fraction of the population. A quite effective and inexpensive method of a rough but very rapid overall assessment of total allergen level in the environment has been developed. The method involved estimation of protein in allergen extracts by screen‐printed electrodes using two different techniques. The biosensor comprised a rhodinised carbon working electrode, a silver/silver chloride reference electrode and a carbon counter electrode. In the first method the enzyme protease reacted with allergen protein to release amino acid, which produced hydrogen peroxide in the presence of amino acid oxidase. This was detected amperometrically. The second method used potassium bromide as electrolyte and the electrode was subjected to dual potential. Bromine, released due to electrolysis at higher potential, was consumed by the allergen protein at lower potential. In the first method, a unique technique was used to microencapsulate the enzyme protease and immobilise it on the surface of the electrode by in‐situ polymerisation to avoid contact with the amino acid oxidase. A total of seven allergens were tested and the results gave a good correlation with the standard protein measurement method. Environmental specimens from indoors, schools and workplaces can be evaluated for the aeroallergens produced by dust mites, animal hairs, cockroach debris, pollens, etc as a means of determining the exposure risk. Copyright © 2005 Society of Chemical Industry     

Molecular structural basis of ligand selectivity for 5-HT2 versus 5-HT1C cortical receptors

A molecular structural criterion of ligand selectivity for the 5-HT2 versus 5-HT1C receptor was hypothesized on the basis of radioligand binding data. Despite the large number of compounds which have been tested at both receptors, analysis of published data led to the identification of only five agents which are greater than 10-fold selective for the 5-HT2 versus the 5-HT1C receptor. Comparison of the two-dimensional structures revealed that, although these five compounds represent three distinct structural classes, they share a common structural feature located in the region hypothesized to be involved in receptor binding: a carbonyl or carboxyl oxygen interposed spatially between an aromatic ring and nitrogen atom. This structural feature was used to predict the relative selectivity of compounds that had not previously been analyzed at both the 5-HT2 and 5-HT1C receptors. All six drugs tested which contain the identified reactive carbonyl or carboxyl group were found to be selective for the 5-HT2 versus the 5-HT1C receptor with selectivity ratios ranging from 26 to 380. By contrast, three agents which are structurally similar but do not contain the reactive carbonyl or carboxyl group displayed equally high affinity for both receptor binding sites. Since the physiological roles of the 5-HT2 and 5-HT1C receptor are markedly different, it would be of potential clinical and scientific value to utilize this molecular structural feature to further identify chemical compounds which would selectively interact with only one of the two receptors.