Cross-cultural invariance of the Academic Expectations Stress Inventory: Adolescent samples from Canada and Singapore

We provide further evidence for the two-factor structure of the 9-item Academic Expectations Stress Inventory (AESI) using confirmatory factor analysis on a sample of 289 Canadian adolescents and 310 Singaporean adolescents. Examination of measurement invariance tests the assumption that the model underlying a set of scores is directly comparable across groups. This study also examined the cross-cultural validity of the AESI using multigroup confirmatory factor analysis across both the Canadian and Singaporean adolescent samples. The results suggested cross-cultural invariance of form, factor loadings, and factor variances and covariances of the AESI across both samples. Evidence of AESI's convergent and discriminant validity was also reported. Findings from t-tests revealed that Singaporean adolescents reported a significantly higher level of academic stress arising from self expectations, other expectations, and overall academic stress, compared to Canadian adolescents. Also, a larger cross-cultural effect was associated with academic stress arising from other expectations compared with academic stress arising from self expectations.     

N-ω-Carbethoxypentyl-4-quinolones: A New Class of Leukotriene Biosynthesis Inhibitors

6-[(4-Quinolinyl)oxy]hexanoic acids and the corresponding esters were designed and synthesized as inhibitors of the production of arachidonic acid metabolites. The inhibitory activities were assayed in vitro by evaluation of serum leukotriene B₄ and thromboxane B₂ production. While all 6-[(4-quinolinyl)oxy]hexanoic acids and their esters proved to be inactive, the N-alkyl-4-quinolones, obtained as by-products in their synthesis, were found to be a new class of leukotriene biosynthesis inhibitors.     

Induction of chromosomal aberrations and spindle disturbances in Chinese hamster epithelial liver cells in culture by pyrene and benzo[a]pyrene quinones

Regioisomers of pyrene and benzo[a]pyrene quinones were testedfor their ability to induce structural and numerical aberrationsand spindle disturbance in Chinese hamster epithelial liver(CHEL) cells in culture. All quinones tested were clastogenicPyrene-1,8-quinone (P-1,8-Q) and benzo[a]pyrene–3,6–quinone(BP-3,6-Q) induced strikingly high levels of triradials. Inaddition, dicentrics and ring chromosomes were very common inBP-3,6-Q-treated cultures. Isomers of these compounds, pyrene-1,6-quinone(P-1,6-Q) and benzo[a]pyrene-1,6-quinone (BP-1,6-Q), inducedunobtrusive patterns of chromosomal aberrations. We suspectthat the P-1,8-Q and BP-3,6-Q moieties bound to the DNA werestill reactive, and formed crosslinks and/or underwent redoxcycling leading to high local concentrations of reactive oxygenspecies. In addition, P-1,8-Q and BP-3,6-Q induced c-mitoses,hyperdiploidies and polyploidies, in particular endoreduplications.These effects were not seen with the other two test compounds,or they were only detected at the highest concentrations used,which were strongly cytotoxic (c-mitoses with P-1,6-Q, polyploidieswith BP-1,6-Q). ⁶To whom correspondence should be addressed at: European Centre for the Validation of Alternative Methods (ECVAM), Joint Research Centre (JRC), TP58O, 1–21020 Ispra, Italy     

Protein kinase C agonist and antagonist effects in normal human epidermal keratinocytes

Abstract Several lines of evidence implicate protein kinase C (PKC) in the development of basal cell and squamous cell carcinomas, tumors which originate from epidermal keratinocytes. To examine PKC in a model relevant to human skin, we exposed normal human epidermal keratinocytes (NHEK) in serum-free media to a variety of PKC agonists and antagonists. NHEK PKC activity increased up to 10-fold within the 1st hour of exposure to tetradecanoyl phorbol acetate (TPA), and gradually returned to control values within 72 h. TPA-induced PKC activity was enhanced by pretreatment of cultures with protein and RNA synthesis inhibitors. TPA-induced growth arrest and differentiation was antagonized by staurosporine. Down-regulation by bryostatin pretreatment blocked TPA-stimulated differentiation. Our overall conclusion is that activation of PKC in cultured human keratinocytes is required for differentiation. These results are crucial to the analysis of compounds suspected of promoting or inhibiting epidermal tumors.     

Immunological relationship among human adenoviruses of subgenus D

Summary Antigenic relationships between adenoviruses of subgenus D were determined by neutralization tests in HeLa cell cultures by CPE inhibition. For cross-testing, several antisera of the same species were tested against the prototype viruses 39 wild strains belonging to 12 different virus species were also studied. Marked variation in the degree of cross-neutralization between individual sera of the same species was often observed. However, virus strains within a species mostly showed identical serological reactions. Hence, antigenic specificity appears to be a fairly constant property of any one species.Strong cross-neutralizations between species are presumably due to a relationship of the (hexon) antigen, whereas weak cross-neutralizations found between viruses related by hemagglutination-inhibition are due to the (fiber) antigen.Viruses related to adenovirus 15(Mastadenovirus h 15) showed a variety of cross-reactions in neutralization tests. In view of the new species definitions of adenoviruses and to facilitate identification, changes in the classification of Ad 15, 25, 29, and 15/H9 are proposed. The prototypes of Ad 13, 15, 25, 29, and 30 have been cloned by terminal dilution.Aided by a grant from the Bundesministerium für Jugend, Familie und Gesundheit.     

Walking modality affects respiratory muscle action and contribution to respiratory effort

We hypothesized that walking at increased speed or increasing gradient might have different effects on chest wall kinematics and respiratory muscle power components, and contribute differently to respiratory effort sensation. We measured the volumes of chest wall compartments by optoelectronic plethysmography, esophageal, gastric and transdiaphragmatic (P _di) pressures, and the sensation of the respiratory effort by a Borg scale in five normal subjects walking both at ascending gradient with constant speed (AG) and at ascending speed with constant gradient (AS). Chest wall kinematics, evaluated by displacement of chest wall compartments, did not show any significant difference between AS and AG. Muscle power, calculated as the product of mean flow and mean pressure, increased similarly, but its partitioning into pressure and velocity of shortening differed in the two modes. A greater increase in the pressure developed by the abdominal muscles (P _abm) (4.06-fold), and in the velocity of shortening of both rib cage inspiratory muscles (v _rcm,i) (2.01-fold) and the diaphragm (v _di) (1.90-fold) was associated with a lower increase in the pressure developed by the rib cage inspiratory muscles (P _rcm,i) (1.24-fold) and P _di (0.99-fold) with AG. Instead, with AS, a lower increase in P _abm (2.12-fold), v _rcm,i (1.66-fold) and v _di (1.54-fold) was associated with a greater increase in P _rcm,i (1.56-fold) and P _di (1.97-fold). A combination of P _abm and v _di during AG (Wald ²=23.19, P<0.0000), with the addition of P _rcm,i during AS (Wald ²=29.46, P<0.0000), was the best predictor of Borg score. In conclusion, the general strategy adopted by respiratory centers during different walking modes does not differ in terms of ventilation, chest wall kinematics, and respiratory muscle power production, whereas it does in terms of partitioning of power into pressure and velocity of shortening, and respiratory muscle contribution to respiratory effort sensation. Combinations of different patterns of flow and pressure generation made the respiratory effort sensation similar during AS and AG modes.     

Presymptomatic diagnosis of SMA III by genotype analysis

Linkage analysis and prenatal prediction in families segregating autosomal recessive spinal muscular atrophy (SMA) has become feasible since the assignment of the locus responsible for type I-III SMA to region 5q12-q13.3. We have performed a segregation study of SMA in Italian families using molecular probes and highly informative PCR-based polymorphic markers. In one family, a 7-year-old boy affected with type III SMA and an 8-year-old apparently healthy brother had identical haplotypes. These findings prompted us to reexamine the apparently unaffected child. His neurological exam was normal. However, the electromyography (EMG) showed a pattern consistent with chronic SMA. To our knowledge this is the first example of presymptomatic diagnosis of SMA based on genotype analysis. © 1993 Wiley-Liss, Inc.