Latex on Glass: an Appropriate Model for Cartilage-Lubrication Studies?

Latex versus glass has frequently been used as a model system for the investigation of natural lubrication mechanisms, despite its significant differences from articular cartilage pairings. The differences in surface chemistry account for its different behavior in terms of protein adsorption and lubrication. While cartilage is well known for its protein resistance, most proteins present in synovial fluid can non-specifically adsorb onto latex or glass. We have investigated latex-versus-glass lubrication by means of pin-on-disk tribometry in the presence of synovial-fluid proteins and glycoproteins, focusing on the influence of the glass-cleaning procedure on friction. In order to simulate the effects of possible contamination of glass in previous studies, both hydrophilic and hydrophobic glass substrates were tested. Albumin was shown to impair lubrication (in comparison to PBS) when latex was slid against both types of glass surface, whereas bovine synovial fluid (BSF) and alpha-1-acid glycoprotein (AGP) impaired the lubrication of latex versus hydrophilic glass and improved the lubrication of latex versus hydrophobic glass. Protein adsorption on the surfaces was monitored by means of fluorescence imaging and optical waveguide lightmode spectroscopy (OWLS), which revealed a faster and greater amount of adsorption of AGP on hydrophobic surfaces than on hydrophilic ones. The influence of surface chemistry on the friction behavior of BSF and on the adsorption of AGP suggests that it plays a role in determining the relative amounts of adsorbed synovial fluid proteins. When BSF is used as a lubricant in the latex-versus-hydrophobic-glass system, more of the AGP, relative to albumin, appears to adsorb on both surfaces, counteracting the negative effect of albumin on friction. It therefore seems that latex on glass, while displaying nominal similarities to cartilage on cartilage under certain conditions, is not a useful model system. Moreover, surface contamination of the glass can play a major role in determining the results.     

Review of Studies in neuropsychology: Selected papers of Arthur Benton.

Reviews the book, Studies in neuropsychology: Selected lepers of Arthur Benton by E. Costa and O. Spreen. This current volume stands as a monument to the contribution that Benton has made to the field of neuropsychology since his resignation from the Civilian Conservation Corp in 1936. This volume contains 29 articles by Benton and his many colleagues, one of which is a hitherto unpublished work on aphasia. These articles span the years 1956-84 and remind those of us who are familiar only with a few of Benton's most seminal papers of the breadth of his interests, which range from classical medical history to the experimental technology of the present. What better compliment for a book than to say that it has whetted one's appetite for more by the same author. In all, I believe that the editors are to be congratulated for providing an important source book for students in the field of neuropsychology. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Electrolyser-based energy management: a means for optimising the exploitation of variable renewable-energy resources in stand-alone applications

Electrolyser-based energy management (EBM) offers a versatile means for optimising the process of harnessing energy supplies derived from variable and/or intermittent renewable resources, e.g. solar (photo-voltaic), wind, wave and tidal. In general, EBM systems consist of an electrolyser, water and gas (hydrogen and, optimally, oxygen) storage and management systems and a means of (re-) generating electricity, e.g. a fuel cell. Such systems achieve their management via energy conversion and storage, this operational principle being referred to as electricity supply-and-demand management (ESDM). Implementation of this principle offers significant advantages in the utilisation of variable and/or intermittent renewable resources, as it permits electricity generated during periods of high-availability/low-demand to be “time-shifted” for subsequent re-supply during periods of low-availability/high-demand. Furthermore, EBM systems have the important advantage over other ESDM systems that the stored form of energy is readily utilisable as a pollution-free gas supply for thermal end-uses. This reconversion route significantly enhances the overall energy-conversion efficiency. Electrolyser and fuel cells based upon proton-exchange membrane technologies are preferred because these afford considerable operational advantages over any alternatives. In this paper these advantages are expanded upon and preliminary data based on these ideas are presented.     

Role of orlistat in the treatment of obese patients with type 2 diabetes. A 1-year randomized double-blind study

OBJECTIVE: Obesity is an important risk factor for type 2 diabetes. Weight loss in patients with type 2 diabetes is associated with improved glycemic control and reduced cardiovascular disease risk factors, but weight loss is notably difficult to achieve and sustain with caloric restriction and exercise. The purpose of this study was to assess the impact of treatment with orlistat, a pancreatic lipase inhibitor, on weight loss, glycemic control, and serum lipid levels in obese patients with type 2 diabetes on sulfonylurea medications. RESEARCH DESIGN AND METHODS: In a multicenter 57-week randomized double-blind placebo-controlled study, 120 mg orlistat or placebo was administered orally three times a day with a mildly hypocaloric diet to 391 obese men and women with type 2 diabetes who were aged > 18 years, had a BMI of 28-40 kg/m2, and were clinically stable on oral sulfonylureas. Changes in body weight, glycemic control, lipid levels, and drug tolerability were measured. RESULTS: After 1 year of treatment, the orlistat group lost 6.2 +/- 0.45% (mean +/- SEM) of initial body weight vs. 4.3 +/- 0.49% in the placebo group (P < 0.001). Twice as many patients receiving orlistat (49 vs. 23%) lost > or = 5% of initial body weight (P < 0.001). Orlistat treatment plus diet compared with placebo plus diet was associated with significant improvement in glycemic control, as reflected in decreases in HbA1c (P < 0.001) and fasting plasma glucose (P < 0.001) and in dosage reductions of oral sulfonylurea medication (P < 0.01). Orlistat therapy also resulted in significantly greater improvements than placebo in several lipid parameters, namely, greater reductions in total cholesterol, (P < 0.001), LDL cholesterol (P < 0.001), triglycerides (P < 0.05), apolipoprotein B (P < 0.001), and the LDL-to-HDL cholesterol ratio (P < 0.001). Mild to moderate and transient gastrointestinal events were reported with orlistat therapy, although their association with study withdrawal was low. Fat-soluble vitamin levels generally remained within the reference range, and vitamin supplementation was required in only a few patients. CONCLUSIONS: Orlistat is an effective treatment modality in obese patients with type 2 diabetes with respect to clinically meaningful weight loss and maintenance of weight loss, improved glycemic control, and improved lipid profile.     

The hepatopulmonary syndrome: radiologic findings in 10 patients

OBJECTIVE: The purpose of this study was to review the radiologic manifestations of the hepatopulmonary syndrome. MATERIALS AND METHODS: We retrospectively reviewed clinical records, chest radiographs, 99m Tc-macroaggregated albumin (MAA) perfusion lung scans, chest CT scans, and pulmonary angiograms of 10 patients with proven hepatopulmonary syndrome. RESULTS: Chest radiographs showed basilar, medium-sized (1.5-3.0 mm) nodular or reticulonodular opacities in all cases. CT was done in eight cases and showed basilar dilatation of lung vessels with a larger than normal number of visible branches. The vascular basis for these opacities was best appreciated on conventional CT scans of 10-mm sections. No individual arteriovenous malformations were seen on CT scans. High-resolution CT scans showed no evidence of interstitial fibrosis. 99mTc-MAA perfusion lung imaging, done in seven patients, showed pulmonary arteriovenous shunting in five. Contrast echocardiography confirmed intrapulmonary shunting in these five patients. Pulmonary angiography, done in four cases, showed subtle distal vascular dilatation in two and moderate dilatation with early venous filling in two but did not reveal any individual arteriovenous malformations. CONCLUSION: Chest radiographs in hepatopulmonary syndrome usually show bibasilar nodular or reticulonodular opacities. Conventional CT shows that these opacities represent dilated lung vessels. High-resolution CT is useful in excluding pulmonary fibrosis or emphysema as the cause of these opacities. 99mTc-MMA perfusion imaging or contrast echocardiography can be used to confirm intrapulmonary arteriovenous shunting.     

Relationship between WPPSI and Stanford-Binet IQs and subsequent WISC IQs in Headstart children.

18 males and 24 females were tested on 2 IQ tests in the concluding weeks of a Head Start program in 1968-1969 and were retested on the WISC in 1972. In comparison to the Wechsler Preschool and Primary Scale of Intelligence, the Stanford-Binet seems better able to predict WISC scores. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Some factors affecting the amount of information sought about others.

This investigation examined the effects upon the amount of information that Ss would seek about others of: (a) the sex of the S; (b) whether the information was all positive, all negative, or ambivalent; and (c) the sex of the other person. The results indicate that female Ss seek more information than males, that Ss seek more ambivalent than univalent information, and that less information is sought when the other person is a woman than when the other is a man. The valence of the final impression was clearly related to the valence of the information that Ss received, although male Ss formed a highly negative impression of women who were described in ambivalent terms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)