Marker selection for the transmission/disequilibrium test, in recently admixed populations

Various analytical, iterative and rebinning algorithms have been proposed for 3D reconstruction in positron emission tomography. This paper examines execution times of five analytical and rebinning algorithms. Meaningful comparisons are obtained by using similar software modules in all implementations. Reconstruction times are shown to differ by vast amounts: the Favor algorithm of Defrise et al is more than twice as fast as the widely used reprojection algorithm of Kinahan and Rogers; the Fourier rebinning algorithm (Fore) recently developed by Defrise is more than 15 times faster than the reprojection algorithm.     

Expression of sialyltransferase is not required for interaction of Neisseria gonorrhoeae with human epithelial cells and human neutrophils

Sialyltransferase (Stase) in Neisseria gonorrhoeae organisms (gonococci [GC]) transfers sialic acid (N-acetylneuraminic acid [NANA]) from cytidine 5'-monophospho-N-acetylneuraminic acid (CMP-NANA) mainly to the terminal galactose (Gal) residue in the Gal beta-1,4 N-acetylglucosamine (Gal-GlcNAc)-R lipooligosaccharide (LOS) structure. Sialylated GC resist killing by normal human serum, sometimes show reduced invasion of epithelial cells, and have reduced adhesion to and stimulation of human neutrophils. We questioned whether Stase itself modulates the interactions of GC with human epithelial cells and neutrophils in the absence of exogenous CMP-NANA. To that end, we treated strain F62 with ethyl methanesulfonate and grew approximately 175,000 colonies on CMP-NANA plates, and screened them with monoclonal antibody 1B2-1B7 (MAb 1B2). MAb 1B2 is specific for Gal-GlcNAc and reacts only with asialylated GC. We isolated 13 MAb 1B2-reactive mutants, including five null mutants, that had Stase activities ranging from barely detectable to fivefold less than that of wild-type (WT) F62. The LOS phenotype of Stase null mutants was identical to that of WT F62, yet the mutants could not sialylate their LOS when grown with CMP-NANA. The Stase null phenotype was rescuable to Stase+ by transformation with chromosomal DNA from WT F62. Stase null mutants remained serum sensitive even when grown with CMP-NANA. One Stase null mutant, ST94A, adhered to and invaded the human cervical epithelial cell line ME-180 at levels indistinguishable from that of WT F62 in the absence of CMP-NANA. In human neutrophil studies, ST94A stimulated the oxidative burst in and adhered to human neutrophils at levels similar to those of WT F62. ST94A and WT F62 were also phagocytically killed by neutrophils at similar levels. These results indicate that expression of Stase activity is not required for interaction of GC with human cells.     

Characterization of three new apparently related high frequency antigens

1. To study the relative contributions of luminal nutrition, bile and pancreatic secretions and hormonal factors in intestinal adaptation, lactation hyperphagia was chosen as a model for increased luminal nutrition, either alone (intestinal transection control group) or in combination with (i) exclusion of bile and pancreatic secretions from the jejunum (by transposition of the jejunum above the Ampulla of Vater) or (ii) exclusion of bile, pancreatic secretions and exogenous luminal nutrition from the jejunum (proximal Thiry-Vella by-pass group). 2. The results confirm that in lactation there is mucosal hyperplasia with increases in villus height and crypt depth, and in small-bowel wet and defatted dry-tissue weights per unit length of intestine. 3. There are corresponding changes in absorptive function with increased glucose and water absorption per unit length of intestine. 4. These structural and functional adaptive changes are proportionately greater in ileum than in jejunum. 5. The exclusion of exogenous luminal nutrition, bile and pancreatic secretions from the jejunum did not diminish the degree of intestinal mucosal hyperplasia and functional adaptation seen in lactation. 6. Diversion to the ileum of greater than normal amounts of bile, pancreatic secretions and luminal nutrition did not further increase the degree of mucosal hyperplasia and enhanced absorption seen in the lactating intestinal transection control group. 7. Unlike other models of intestinal adaptation, the changes in small-bowel mucosal structure and function seen in lactation are probably due to hormonal factors.     

Calcareous deposits formed on IUDs in human exposures

Characteristics of the calcareous deposits on several hundred IUDs of various designs and materials following in vivo exposures were examined, and an in vitro method of study was devised. There were 650 copper-wound IUDs and 18 plastic IUDs. The copper-wound IUDs had been in the uteri for 6-27 months; the plastic IUDs for 3 months to over 8 years. Microscopic examinations, X-ray diffraction, weight changes, and chemical analyses were used. X-ray diffraction showed that calcite (CaCO3) was the major crystalline constituent of the calcareous deposits. A large fraction of the deposited material was organic. Surfaces in contact with the uterine wall were essentially free of depos its. Microscopic inspection of copper-wound IUDs revealed the amount of deposit. Length of exposure increased the amount of deposit, but there were marked variations in amount. Accumulation of deposits was mostly at the fundal end. More marked local erosion of copper was noted where there was little or no carbonate deposit. Deposits occurred in patches on Lippes loops and Margulies spirals. The in vitro carbonate deposits did not reproduce the rates or morphology of the in vivo deposits. Variations in uterine carbonate formation are attributed to differences in uterine chemistry of individuals.