Reliability of peer and self-assessment scores compared with trainers' scores following third molar surgery

Context It is sometimes claimed that self‐assessment is inaccurate and that clinicians over‐rate their performance. There is a need to find out why this should be. Is poor self‐assessment caused by some clinicians' inability to accurately judge performance? Or does over‐scoring result from a desire to convey a more favourable impression? Peer assessment is widely advocated and is said to be of benefit to both assessor and assessee. Methods In this study, we wanted to see if postgraduates were able to peer‐assess and if this form of assessment was more reliable than self‐assessment when compared with assessment by a trainer. We used checklist and global rating scales to evaluate surgical skills in removing a mandibular third molar tooth. Results There was no statistically significant difference between peer‐assessed and trainer‐assessed scores. We found that, on average, peer assessment (especially global rating scales) reflected trainer scores more accurately than self‐assessment of surgical skills. Self‐assessment scores were significantly higher on average than those given in peer assessment. Discussion Although peers and trainee surgeons came from the same group, the surgeons were more likely to over‐score when measuring their own performances. The greatest variability (and over‐scoring) between assessor and trainee surgeon appeared to occur in those with lower mean scores. Formative peer assessment may be a useful and less stressful mechanism for encouraging reflection.     

Effects of Binding and Bactericidal Action of Vancomycin on Bacillus licheniformis Cell Wall Organization as Probed by 15N Nuclear Magnetic Resonance Spectroscopy

The effects of binding and the bactericidal action of vancomycin on the arrangement and mobilities of cell wall polymers in Bacillus licheniformis were investigated by ¹⁵N nuclear magnetic resonance spectroscopy. The bactericidal action of vancomycin led to reduced mobilities of cell wall teichoic acid and teichuronic acid in surviving cells. The decrease in teichoic acid mobility was also observed upon binding of vancomycin to B. licheniformis cells and resulted from a specific interaction between the antibiotic and teichoic acid, rather than from electrostatic contraction of the cell wall. The reduction in teichuronic acid mobility appeared to be related either to the elastic contraction of the cell wall resulting from loss of cell turgor or to separation of the cell wall from the protoplast membrane. No spectral changes associated with cell wall autolysis or alterations in cell wall composition, amidation, and cross-linking were found in vancomycin-treated B. licheniformis cells. Binding of vancomycin to Micrococcus lysodeikticus cell walls led to a decrease in mobility of C-terminal d-alanine residues but was accompanied by an increase in the mobilities of other peptidoglycan residues. The possible contributions of changes in the arrangements of cell wall polymers to the lethal action of vancomycin is discussed.     

Isolation and localization of DNA segments from specific human chromosomes

Recombinant DNA techniques have been combined with somatic cell genetic methods to identify, isolate, and amplify fragments of human DNA localized at specific regions of human chromosome 11 selected as a model system. A library of genomic DNA segments has been constructed, in λ Charon 4A bacteriophage, from the DNA of a somatic cell hybrid carrying a portion of human chromosome 11 on a Chinese hamster ovary cell background. Using a nucleic acid hybridization technique that distinguishes human and Chinese hamster interspersed, repetitive DNA, we have been able to distinguish recombinant phages carrying DNA segments of human origin from recombinant phages carrying DNA segments of Chinese hamster origin. We have isolated 50 human DNA segments thus far and have characterized 5 in detail. For each DNA segment characterized, a subsegment that carries no repetitive human DNA sequences has been identified. These segments have been used as hybridization probes in experiments that localize the DNA fragment on the chromosome. In each case an unequivocal chromosomal localization has been obtained with reference to a panel of hybrid cell clones each of which carries a deletion of a portion of the short arm of chromosome 11. At least one DNA segment has been identified which maps to each of the four regions on the short arm defined by the panel of hybrid cell clones used. The approaches described here appear to be general. They can be extended to produce a fine structure map of human chromosome 11 and other human chromosomes. This approach promises implications for human genetics generally, for the human genetic diseases, and possibly for understanding of gene regulation in normal and abnormal differentiation.     

CB2 cannabinoid receptor agonist enantiomers HU-433 and HU-308: An inverse relationship between binding affinity and biological potency

Activation of the CB2 receptor is apparently an endogenous protective mechanism. Thus, it restrains inflammation and protects the skeleton against age-related bone loss. However, the endogenous cannabinoids, as well as Δ⁹-tetrahydrocannabinol, the main plant psychoactive constituent, activate both cannabinoid receptors, CB1 and CB2. HU-308 was among the first synthetic, selective CB2 agonists. HU-308 is antiosteoporotic and antiinflammatory. Here we show that the HU-308 enantiomer, designated HU-433, is 3–4 orders of magnitude more potent in osteoblast proliferation and osteoclast differentiation culture systems, as well as in mouse models, for the rescue of ovariectomy-induced bone loss and ear inflammation. HU-433 retains the HU-308 specificity for CB2, as shown by its failure to bind to the CB1 cannabinoid receptor, and has no activity in CB2-deficient cells and animals. Surprisingly, the CB2 binding affinity of HU-433 in terms of [³H]CP55,940 displacement and its effect on [³⁵S]GTPγS accumulation is substantially lower compared with HU-308. A molecular-modeling analysis suggests that HU-433 and -308 have two different binding conformations within CB2, with one of them possibly responsible for the affinity difference, involving [³⁵S]GTPγS and cAMP synthesis. Hence, different ligands may have different orientations relative to the same binding site. This situation questions the usefulness of universal radioligands for comparative binding studies. Moreover, orientation-targeted ligands have promising potential for the pharmacological activation of distinct processes.The CB2 cannabinoid receptor functions as an endogenous protective entity (1). Thus, it is an important regulator of bone mass and inflammation. It represents a therapeutic target that avoids the undesired psychotropic effects caused by CB1 receptor activation. CB2 is expressed in osteoblasts, the bone-forming cells, and in osteoclasts, the bone-resorbing cells (2). Monocytes/macrophages, B cells, certain T-cell subtypes, and mast cells also express CB2 (3–7). In the skeleton, activation of CB2 favors bone formation over resorption, thus protecting the skeleton against age-related bone loss. Inflammatory responses are restrained by CB2 agonists in several instances such as hepatic ischemia-reperfusion injury (8), uveitis (9), and contact dermatitis (10). With their terpene and resorcinol-derived moieties, some synthetic CB2 agonists, such as HU-308 (10), JWH-133 (11), and HU-910 (12), structurally resemble the phytocannabinoids Δ⁹-tetrahydrocannabinol and cannabidiol. Other, non-phytocannabinoid-type agonists have been also reported (13). HU-308 was one of the first fully characterized, highly selective, and highly efficacious cannabinoid type-2 agonist (10). It has three chiral centers, namely, at carbon atoms in positions 3, 4, and 6 (Scheme 1). HU-308 has a 3R, 4S, 6S configuration; that of its enantiomer (HU-433) is 3S, 4R, 6R.Open in a separate windowScheme 1.Structures of HU-433 and -308.In most experiments, the optimal HU-308 mitogenic activity in osteoblasts, as well as its antiosteoclastogenic effect, was obtained by using concentrations in the nanomolar range (2, 14). Surprisingly, testing a new HU-308 batch, we noticed a 3- to 4-magnitude decrease in the dose that triggers optimal proliferative response in osteoblasts, reasoning that this preparation contained a significant amount of the HU-308 enantiomer, presumably responsible for the enhanced activity. We report here that this enantiomer, designated HU-433, was synthesized and compared with HU-308, and indeed showed markedly enhanced bone-anabolic and antiinflammatory activities, but inferior CB2 receptor binding affinity. Although both enantiomers seem to target the same binding pocket, two different orientations relative to the binding site are possible, leading to different behavior of the two enantiomers due to their different occupancy of these orientations. This observation appears to reflect a situation in which relatively small differences in possible binding conformations of the ligands within the receptor—referred to as poses—lead to significant diminution of receptor-binding properties and a marked increase in biological activity.     

Racial and Ethnic Differences in Depression by Partner Status and the Presence of Children in the Household

PurposeSingle motherhood is a well-established risk factor for depression in women. The goal of this study is to analyze the relationships among partner status, having children, and depression among women of White, Black, and Hispanic race/ethnicity.MethodsStratified analyses were conducted on 2002, 2003, 2005, 2006, and 2008 cross-sectional survey data from 10,520 White women, 7,655 Black women, and 7,343 Hispanic women aged at least 18 years and residing in New York City. Depression was evaluated using Kessler's K6 scale. Race/ethnicity-specific logistic regression analysis assessed the association between partner status and depression among women with and without children.ResultsPartner status was significantly associated with depression among White (p < .0001) and Hispanic (p = .0001) women, but not among Black women (p = .82), after adjusting for age, nativity, employment, education, poverty level, general health, and health insurance. Among White women, the conditional odds of depression were elevated for single relative to partnered women both with (odds ratio [OR], 2.10; 95% confidence interval [CI], 1.57–2.81; p < .0001) and without (OR, 1.29; 95% CI, 1.06–1.56; p = .01) children, but the size of the effect was significantly larger for those with children than for those without children (p = .006). Among Hispanic women, the conditional odds of depression were elevated for single relative to partnered women with children (OR, 1.58; 95% CI, 1.29–1.95; p < .0001), but not for single versus partnered women without children (OR, 1.09; 95% CI, 0.82–1.46; p = .54). Among Black women, there was no evidence of elevated depression in single relative to partnered women, either overall or conditional on the presence of children (with children: OR, 1.21 [95% CI, 0.95–1.54; p = .13]; without children: OR, 0.75 [95% CI, 0.56–1.02; p = .06]).ConclusionPast focus on single mothers as a high-risk group has oversimplified the relationship between partner status and depression, obscuring important distinctions between women of different racial backgrounds.     

Meals in Our Household: reliability and initial validation of a questionnaire to assess child mealtime behaviors and family mealtime environments

Mealtimes in families with young children are increasingly of interest to nutrition and public health researchers, yet assessment tools are limited. Meals in Our Household is a new parent-report questionnaire that measures six domains: 1) structure of family meals, 2) problematic child mealtime behaviors, 3) use of food as reward, 4) parental concern about child diet, 5) spousal stress related to child's mealtime behavior, and 6) influence of child's food preferences on what other family members eat. Reliability and initial face, construct, and discriminant validity of the questionnaire were evaluated between January 2007 and December 2009 in two cross-sectional studies comprising a total of 305 parents of 3- to 11-year-old children (including 53 children with autism spectrum disorders). Internal consistencies (Cronbach's α) for the six domains averaged .77 across both studies. Test-retest reliability, assessed among a subsample of 44 parents who repeated the questionnaire after between 10 and 30 days, was excellent (Spearman correlations for the domain scores between two administrations ranged from 0.80 to 0.95). Initial construct validity of the instrument was supported by observation of hypothesized inter-relationships between domain scores that were of the same direction and similar magnitude in both studies. Consistent with discriminant validity, children with autism spectrum disorders had statistically significantly (P<0.05) higher domain scores for problematic child mealtime behaviors, use of food as reward, parental concern about child diet, and spousal stress, as compared to typically developing children. Meals in Our Household may be a useful tool for researchers studying family mealtime environments and children's mealtime behaviors.