An ab initio MO study on the structures and electronic states of hydrogen-bonded O3- HF and SO2-HF complexes.

Ab initio molecular orbital (MO) calculations have been carried out for base-hydrogen fluoride (HF) complexes (base = O3 and SO2) in order to elucidate the structures and energetics of the complexes. The ab initio calculations were performed up to the QCISD(T)/6-311++G(d,p) level of theory. In both complexes, hydrogen-bonded structures where the hydrogen of HF orients toward one of the oxygen atoms of bases were obtained as stable forms. The calculations showed that cis and trans isomers exist in both complexes. All calculations for the SO2-HF complex indicated that the cis form is more stable in energy than the trans form. On the other hand, in O3-HF complexes, the stable structures are changed by the ab initio levels of theory used, and the energies of the cis and trans forms are close to each other. From the most sophisticated calculations (QCISD(T)/6-311++G(d,p)//QCISD/6-311+G(d) level), it was predicted that the complex formation energies for cis SO2-HF, trans SO2-HF, cis O3-HF, and trans O3-HF are 6.1, 5.7, 3.4, and 3.6 kcal/mol, respectively, indicating that the binding energy of HF to SO2 is larger than that of O3. The harmonic vibrational frequencies calculated for cis O3-HF and cis SO2-HF complexes were in good agreement with the experimental values measured by Andrews et al. Also, the calculated rotation constants for cis SO2-HF agreed with the experiment.

beta-Carotene accumulation in mouse tissues and a protective role against lipid peroxidation.

Mice were supplemented with beta-carotene in beverage for 10 days. After the supplement, beta-carotene accumulated mainly in the liver and to some extent in the blood plasma, kidney and lung. The beta-carotene administration was associated with an increase in the amount of retinyl ester and retinol in the liver, but not in the amount of retinol in blood plasma. Lipid peroxidation in vivo was induced by the injection of carbon tetrachloride under the dorsal skin of mice. As an index of lipid peroxidation, thiobarbituric acid-reacting substances (TBARS) were assayed in urine and tissue homogenates. Urine and kidney TBARS were reduced by the supplementation of beta-carotene. The amounts of TBARS in kidney, liver and lung, decreased with increasing amounts of beta-carotene accumulated in these tissues, i.e. inverse correlations were obtained. These results indicate that beta-carotene can suppress lipid peroxidation in mouse tissue.

Osteopetrosis: further heterogeneity.

A form of osteopetrosis is described in two sibs which differs from the well-established autosomal dominant and recessive forms. The clinical course is mild with no evidence of clinically important encroachment upon the bone marrow or cranial nerve foramina; the skeletal radiographs show a mild generalized increase in bone density and metaphyseal modeling defects affecting primarily the distal femurs. The inheritance pattern is compatible with either an autosomal or X-linked recessive mode. The histologic features are distinct as well, and suggest that the pathogenesis of the condition differs from that of the usual forms of osteopetrosis.