Molecular mapping of the Edwards syndrome phenotype to two noncontiguous regions on chromosome 18.

In an effort to identify regions on chromosome 18 that may be critical in the appearance of the Edwards syndrome phenotype, we have analyzed six patients with partial duplication of chromosome 18. Four of the patients have duplications involving the distal half of 18q (18q21.1-qter) and are very mildly affected. The remaining two patients have most of 18q (18q12.1-qter) duplicated, are severely affected, and have been diagnosed with Edwards syndrome. We have employed FISH, using DNA probes from a chromosome 18-specific library, for the precise determination of the duplicated material in each of these patients. The clinical features and the extent of the chromosomal duplication in these patients were compared with four previously reported partial trisomy 18 patients, to identify regions of chromosome 18 that may be responsible for certain clinical features of trisomy 18. The comparative analysis confirmed that there is no single region on 18q that is sufficient to produce the trisomy 18 phenotype and identified two regions on 18q that may work in conjunction to produce the Edwards syndrome phenotype. In addition, correlative analysis indicates that duplication of 18q12.3-q22.1 may be associated with more severe mental retardation in trisomy 18 individuals.     

Low-affinity Na+ sites on (Na+ +K+)-ATPase modulate inhibition of Na+-ATPase activity by vanadate

Na+-ATPase activity is extremely sensitive to inhibition by vanadate at low Na+ concentrations where Na+ occupies only high-affinity activation sites. Na+ occupies low-affinity activation sites to reverse inhibition of Na+-ATPase and (Na+, K+)-ATPase activities by vanadate. This effect of Na+ is competitive with respect to both vanadate and Mg2+. The apparent affinity of the enzyme for vanadate is markedly increased by K+. The principal effect of K+ may be to displace Na+ from the low-affinity sites at which it activates Na+-ATPase activity.     

The use of hydroxyapatite cement in secondary craniofacial reconstruction.

Sixty-one patients underwent secondary craniofacial reconstruction for contour defects using hydroxyapatite cement over a 3-year period (20-month mean follow-up). There were 56 children, aged 2.2 to 18 years (mean, 10.7 years), 21 boys and 35 girls. This is the first series of pediatric patients in whom the use of hydroxyapatite cement has been reported. There were five adults aged 21 to 46 years (mean, 32 years), 3 men and 2 women. Thirty-one patients underwent reconstruction for secondary orbitocranial defects after surgery for synostosis, 7 after surgery for hypertelorism, 10 for posttraumatic skull defects, and 13 for a variety of other facial skeletal defects. There were seven complications (11 percent), ranging from a retained drain to postoperative seromas, all of which required reoperation without loss of the contour correction. All of the complications occurred in the first 18 months of our study. There has been excellent retention of implant volume with no recurrence of contour defects to date. We have not found any visible evidence of interference with craniofacial growth over the study period. We conclude that hydroxyapatite cement is a versatile and safe biomaterial when used for the correction of secondary craniofacial contour defects in children and adults. The coupling of antibiotics with this biomaterial may have applications in the treatment of osteomyelitis.     

Studies of consomic mice bearing the Y chromosome of the BXSB mouse

Previous studies have demonstrated that the Y chromosome of the BXSB mouse can lead to accelerated autoimmunity in inbred BXSB mice and in F1 hybrids. To additionally study the effects of the BXSB-Y, we have studied three sets of Y-consomic mice, NZB.BXSB-Y, NZW.BXSB-Y, and CBA/J.BXSB-Y, each consisting of background genes from the non-BXSB parent and the Y chromosome from the BXSB mouse. The effect of the BXSB-Y on autoantibody production, immunopathology, and survival was assessed. We found that the CBA/J.BXSB-Y mice showed few differences from control CBA/J males. In contrast, NZW.BXSB-Y males had accelerated renal and cardiac disease and early death, resembling that previously reported for (NZW X BXSB)F1 mice. NZB.BXSB-Y males had accelerated anti-erythrocyte autoantibodies but not accelerated anti-DNA. They lived almost as long as NZB mice. The presence of the BXSB-Y in all of the consomic mice was confirmed by crossing the consomic mice with BXSB females and demonstrating accelerated disease in the male offspring. This study demonstrates that the BXSB-Y chromosome autoimmune accelerating factor does not act alone but operates through other genes, and that the effects on different genetic backgrounds are different. The studies have implications for human lupus; they also provide a basis for future molecular biology studies of the BXSB-Y and the genes upon which it acts.     

Predicting the spread of all invasive forest pests in the United States

We tested whether a general spread model could capture macroecological patterns across all damaging invasive forest pests in the United States. We showed that a common constant dispersal kernel model, simulated from the discovery date, explained 67.94% of the variation in range size across all pests, and had 68.00% locational accuracy between predicted and observed locational distributions. Further, by making dispersal a function of forest area and human population density, variation explained increased to 75.60%, with 74.30% accuracy. These results indicated that a single general dispersal kernel model was sufficient to predict the majority of variation in extent and locational distribution across pest species and that proxies of propagule pressure and habitat invasibility – well‐studied predictors of establishment – should also be applied to the dispersal stage. This model provides a key element to forecast novel invaders and to extend pathway‐level risk analyses to include spread.