Leisure Activities of Individuals With Prader-Willi, Williams, and Down Syndromes

This study extends laboratory-based profiles to participation in leisure activities for persons with three genetic syndromes. Parents of 223 persons with Prader-Willi, Williams, and Down syndromes filled out a newly developed Leisure Activities Questionnaire. Sixteen items loaded onto five distinct factors: social; visual-spatial; visual-strategy; musical; and physical activities. Individuals with Williams syndrome less often participated in visual-spatial activities, those with Prader-Willi syndrome more often performed both visual-spatial and visual-strategy activities, and those with Williams and Down syndromes more often performed musical activities. With increasing chronological ages, all groups increased in their social activities, while those with Williams and Down syndromes decreased in their visual-spatial activities. In both Prader-Willi and Williams syndrome, decreased maladaptive behaviors related to greater amounts of participation in etiology-related activities. Theoretical and practical implications are discussed.     

Classical Noonan syndrome is not associated with deletions of 22q11

Deletions of 22qll cause DiGeorge sequence (DGS), velo-cardio-facial syndrome (VCFS), conotruncal anomaly face syndrome, and some isolated conotruncal heart anomalies. Demonstration of a 22qll deletion in a patient with manifestations of DGS and Noonan syndrome (NS) has raised the question of whether NS is another of the chromosome 22 microdeletion syndromes. This prompted us to evaluate a cohort of patients with NS for evidence of 22qll deletions. Five of 6 NS propositi studied in our laboratory with marker N25 (D22S75) did not have a 22qll deletion. A 2-month-old infant with several findings suggestive of NS did have a 22qll deletion, suggesting that a small number of 22qll deletion propositi may present with a NS-like picture. However, most cases of NS must have another cause. © 1995 Wiley-Liss, Inc.     

Mechanism of mercurial inhibition of sodium-coupled alanine uptake in liver plasma membrane vesicles from Raja erinacea

In mammalian hepatocytes the L-alanine carrier contains a sulfhydryl group that is essential for its activity and is inhibited by mercurials. In hepatocytes of the evolutionarily primitive little skate (Raja erinacea), HgCl2 inhibits Na(+)-dependent alanine uptake and Na+/K(+)-ATPase and increase K+ permeability. To distinguish between direct effects of HgCl2 on the Na(+)-alanine cotransporter and indirect effects on membrane permeability, [3H]alanine transport was studied in plasma membrane vesicles. [3H]Alanine uptake was stimulated by an "out-to-in" Na+ but not K+ gradient and was saturable confirming the presence of Na(+)-alanine cotransport in liver plasma membranes from this species. Preincubation of the vesicles with HgCl2 for 5 min reduced initial rates of Na(+)-dependent but not Na(+)-independent alanine uptake in a dose-dependent manner (10-200 microM). In the presence of equal concentrations of NaCl or KCl inside and outside of the vesicles, 75 microM HgCl2 directly inhibited sodium-dependent alanine-[3H]alanine exchange, demonstrating that HgCl2 directly affected the alanine cotransporter. Inhibition of Na(+)-dependent alanine uptake by 30 microM HgCl2 was reversed by dithiothreitol (1 mM). HgCl2 (10-30 microM) also increased initial rates of 22Na uptake (at 5 sec), whereas 22Na uptake rates were decreased at HgCl2 concentrations greater than 50 microM. Higher concentrations of HgCl2 (100-200 microM) produced nonspecific effects on vesicle integrity. These studies indicate that HgCl2 inhibits Na(+)-dependent alanine uptake in skate hepatocytes by three different concentration-dependent mechanisms: direct interaction with the transporters, dissipation of the driving force (Na+ gradient), and loss of membrane integrity. Inactivation of the Na(+)-coupled alanine carrier by mercury in hepatocytes of this evolutionarily primitive vertebrate, as in mammals, suggests that the sulfhydryl groups on this transport protein are highly conserved.     

Physicomechanical evaluation of low-shrinkage dental nanocomposites based on silsesquioxane cores

This study aimed to determine the modulus, hardness, and polymerization shrinkage of novel silsesquioxane (SSQ)-based nanocomposites synthesized for dental applications. Four novel SSQ materials were developed and mixed with control monomers in 5, 10, 20, and 50 wt% SSQ nanocomposite ratios and were evaluated for use as potential low-shrinkage composite restoratives. The postgel polymerization shrinkage of the hybrid materials was then investigated and compared with unfilled 1:1 (control) bisphenol A glycerolate (1 glycerol/phenol) dimethacrylate/tri(ethylene glycol) dimethacrylate (Bis-GMA/TEGDMA) materials using a strain-monitoring device and test configuration. Mechanical properties, such as hardness and modulus, were determined using the depth-sensing microindentation approach. All samples investigated were polymerized using a dental light-curing unit (BISCO VIP) at 500 mW cm(-2) for 40 s. The results obtained were analyzed using analysis of variance/Scheffe's posthoc test at a significance level of 0.05. At 60 min postlight polymerization, postgel shrinkage associated with the control was found to be significantly higher than for all control/SSQ mixtures. Hardness and modulus were found to decrease with increased amount of SSQ monomers added, indicating that the incorporation of SSQ monomers into the control generally helps to reduce both the rigidity and the polymerization shrinkage. Therefore, in the correct formulation, SSQ materials have great potential to be used as low-shrinkage composite restoratives.     

Subvastus approach for total knee arthroplasty

The indications for the subvastus approach in total knee arthroplasty are the same for a medial parapatellar approach in the appropriately selected patient. The subvastus approach does not violate the quadriceps mechanism, reduces the need for lateral retinacular release, preserves the patella blood supply, and, with our modifications, can be used in most cases.     

Metastatic breast cancer in the femur. A search for the lesion at risk of fracture

Clinical records and radiographs of 203 female patients with 516 metastatic breast lesions located in the proximal femur were examined retrospectively to determine: the dimensions of those lesions that were at risk of fracture; and the relationship of other variables (bone pain, body habitus, age, and radiation treatment) with the occurrence of a pathologic fracture. Twenty-three patients sustained 26 pathologic fractures. Their average age, height, and weight were not significantly different from the 180 patients without fractures. Similarly, moderate to severe bone pain was experienced by a great majority of the total patient population, yet only 11% sustained fractures. Fifty-six patients received radiation treatment of a femoral metastasis. Ten of these patients subsequently sustained fractures. Radiation treatment relieved bone pain but did not have any consistent curative effect on the lesion itself. Finally, the authors were unable to identify either a specific percent involvement of the bone or a critical diameter for metastases that fractured because: 296 (57%) of the 516 metastases were permeative lesions and unmeasurable; 14 (54%) of the 26 pathologic fractures observed occurred through unmeasurable lesions; and the 12 measurable lesions that fractured had the same range of percent involvement as the 208 measurable lesions that did not fracture. Breast metastases at risk of fracture cannot be identified by measurements obtained from standard radiographs alone.     

Cerebellar tRNA methyltransferases: A development study

Developmental patterns of homologous and heterologous tRNA methylation by cerebellar tRNA methyltransferases are described. The study revealed that: (a) homologous tRNA methylation results in the predominant formation of N²-methyl-guanine and 1-methyladenine; (b) tRNA methyltransferases of bulk-isolated Purkinje and granule cells methylateE. coli tRNA^glu₂ in vitro in a characteristic manner, and (c) the methylation of 8-day-old cerebellar, cortical and hepatic tRNA in vivo yields tRNAs containing different proportions of methylated bases. The findings suggest that the presumably cell-specific populations of cerebellar tRNA methyltransferases continue to alter their substrate recognition characteristics up to and beyond the first month of post-natal life.     

Beta-alanine uptake is not a marker for brain astroglia in culture

The properties of the beta amino acid transport system were examined in cultivated rat brain astrocytes, using the specific probe, beta-alanine. The uptake of beta-alanine is thought to be glial specific. Beta-alanine was not actively transported and the intracellular accumulation was not altered by coincubation with GABA, alanine, glutamate, or methionine. We suggested therefore that beta-alanine is passively taken up by a mechanism distinct from the transport system for GABA.