It is well established by X-ray crystal analysis that the mineral constituent of bone and of the enamel and dentine of teeth is essentially hydroxy-apatite Ca5OH(PO4)3, and that hydroxy-apatite has a structure differing only in small details from that of the well-crystallized mineral fluor-apatite Ca5F(PO4)3. The main difference, and in fact the only fully established one, between the two structures is that the hydroxy-apatite has a slightly larger unit cell than that of the fluor-apatite. The structure of the latter has been determined by Náray-Szabó, and by Mehmel who finally agrees with Náray-Szabó. We have made what is probably a more accurate determination of the structure, using more extensive X-ray data.

The maintenance of normal body weight is disrupted in patients with anorexia nervosa (AN) for prolonged periods of time. Prior to the onset of AN, premorbid body mass index (BMI) spans the entire range from underweight to obese. After recovery, patients have reduced rates of overweight and obesity. As such, loci involved in body weight regulation may also be relevant for AN and vice versa. Our primary analysis comprised a cross-trait analysis of the 1000 single nucleotide polymorphisms (SNPs) with the lowest p-values in a genome-wide association meta-analysis (GWAMA) of AN (GCAN) for evidence of association in the largest published GWAMA for BMI (GIANT). Subsequently we performed sex-stratified analyses for these 1000 SNPs. Functional ex vivo studies on four genes ensued. Lastly, a look-up of GWAMA-derived BMI related loci was performed in the AN GWAMA. We detected significant associations (p-values < 5×10−5, Bonferroni corrected p < 0.05) for 9 SNP alleles at 3 independent loci. Interestingly, all AN susceptibility alleles were consistently associated with increased BMI. None of the genes (chr. 10: CTBP2, chr. 19: CCNE1, chr. 2: CARF and NBEAL1; the latter is a region with high linkage disequilibrium) nearest to these SNPs has previously been associated with AN or obesity. Sex-stratified analyses revealed that the strongest BMI signal originated predominantly from females (chr. 10 rs1561589; poverall: 2.47 × 10−06/pfemales: 3.45 × 10−07/pmales: 0.043). Functional ex vivo studies in mice revealed reduced hypothalamic expression of Ctbp2 and Nbeal1 after fasting. Hypothalamic expression of Ctbp2 was increased in diet induced obese (DIO) mice as compared to age-matched lean controls. We observed no evidence for associations for the look-up of BMI related loci in the AN GWAMA. A cross-trait analysis of AN and BMI loci revealed variants at three chromosomal loci with potential joint impact. The chromosome 10 locus is particularly promising given that the association with obesity was primarily driven by females. In addition, the detected altered hypothalamic expression patterns of Ctbp2 and Nbeal1 as a result of fasting and DIO implicate these genes in weight regulation.

A study has been carried out on the molecular weight distributions of polystyrene initiated by sodium naphthalene in tetrahydrofuran solution. Stringent high‐vacuum techniques were used in order to minimize initiator destruction or chain termination. Molecular weights were measured by osmotic pressure, dilute solution viscosity, light scattering and sedimentation equilibrium. In general, the molecular weight distributions found were quite narrow, as predicted, and corresponded to a stoichiometry of one polymer chain for two initiator molecules. However, the breadth of the distribution was very sensitive to experimental conditions, the M̄w/M̄n values found ranging from 1.1 to 1.5. At the higher molecular weights, there was some indication of a chain transfer reaction, leading to a lower molecular weight than expected, as well as a broadening of the distribution. This transfer reaction did not appear to be due to any transfer step between the short‐lived radical‐anions and the solvent.

Only three mutant cystic fibrosis (CF) alleles have to date been established as conferring a dominant mild effect on affected subjects who are compound heterozygotes. We now add a fourth, P67L, which occurs on about 1.4% of Scottish CF chromosomes. Among 13 patients (12 unrelated) with this allele, the average age at diagnosis was 22.5±11.3 years. None of the cases had consistently raised sweat chloride concentrations, the average value being 57±9 mmolIl; 77% of the patients were pancreatic sufficient. When compared to three other established mild CF alleles, R117H, A455E, and 3849+10kb C-T, a compound heterozygote for P67L has minimal disease and clinical suspicions are unlikely to be confirmed other than by DNA typing. (JMed Genet 1998;35:122-125)