Response to Lefebvre et al.

Congenital scoliosis (CS) is a common vertebral malformation with incidence of up to 1 of 1000 births worldwide. Recently, TBX6 has been reported as the first disease gene for CS: about 10% of CS patients are compound heterozygotes of rare null mutations and a common haplotype composed by 3 SNPs in TBX6. Lefebvre et al in this journal reported that 2 patients with spondylocostal dysostosis (SCD), a rare skeletal dysplasia affecting spine and ribs also have TBX6 mutations: 1 carried the microdeletion and a rare missense variant, and another 2 rare missense variants. We investigated the pathogenicity of the 3 missense variants in SCD by a luciferase assay. The results were negative for the proposal of Lefebvre et al. We consider these 2 SCD patients are more probably compound heterozygotes of null mutations and a common risk haplotype just as CS patients with TBX6 mutations.

Influence of various superhydrophilic treatments of titanium on the initial attachment, proliferation, and differentiation of osteoblast-like cells.

The purpose of this study was to investigate the influence of superhydrophilic treatments of titanium on the behavior of osteoblastlike cells. Superhydrophilic specimens were prepared with sandblast and acid-etching (DW), oxygen plasma (Plasma) and ultraviolet light (UV), and were stored in distilled water for 3 days immediately after these treatments. Specimens stored in air for 3 weeks were used as a control Air group. Initial cell attachment, proliferation, alkaline phosphatase activity, and osteocalcin secretion of mouse osteoblast-like cells MC3T3-E1 were enhanced more on superhydrophilic groups than were Air specimens. On confocal laser scanning microscope images of cell morphology, the expression of actin filaments was observed on the superhydrophilic groups, whereas relatively little actin filament expression was seen on the Air surfaces on all culture periods. These results indicate that DW, Plasma, or UV treatment has potential for the creation and maintenance of superhydrophilic surfaces and the enhancement of the initial attachment, proliferation, and differentiation of osteoblast-like cells.

Vascular reactivity of isolated perfused kidneys from normotensive, renal hypertensive and spontaneously hypertensive rats.

By means of an isolated kidney perfusion technique, reactivities of renal body vessels to electrical stimulation of renal plexus and intravascular administrations of low dosed norepinephrine and epinephrine were determined in the spontaneously hypertensive rats of Wistar strain, normotensive Sprague-Dawley rats and Sprague-dawley rats with renal hypertension of the same sex and as equal as possible with respect to age and body weight. The basal vascular resistance as indicated by the perfusion pressure caused by the same rat of perfusion was significantly higher in the renal hypertensive group. Both electrical stimulation of the renal plexus and intravascular administrations of catecholamines caused a rise of perfusion pressure. Analysis of the dose-response relationship reveals that in the dose range used, the sensitivities to electrical stimulation and to norepinephrine are significantly higher in the normotensive than the hypertensive groups. The results indicate that structural change in the blood vessels is more important than the adrenergic actions of low intensity in the cause of high resistance of blood flow in hypertensive subjects at least in the kidney.

The analysis of 25-hydroxycholesterol in plasma and cholesterol-containing foods by high-performance liquid chromatography.

A method for the analysis of 25-hydroxycholesterol by high-performance liquid chromatography (HPLC) in a wide range of materials is described. Lipid extracts were initially purified on octadecyl silicic acid cartridges and by reversed-phase HPLC before quantitation by HPLC on a silicic acid column. The reproducibility of the method was confirmed by the analysis of plasma from rats fed 25-hydroxycholesterol. 25-Hydroxycholesterol was not detected in lard, cream, fresh egg yolk or spray-dried egg yolk powder. It was detected in egg yolk powder after heating at 110 degrees C for 4 days and its authenticity was confirmed by mass spectrometry.

Influence of 26-hydroxycholesterol on the composition and function of gel-filtered platelets.

The influence of 26-hydroxycholesterol (26-OH-CHOL) on the structure and function of gel-filtered rat platelets, as a model membrane, was studied in vitro. Its influence on structure was determined by a fatty acid and a phospholipid analysis of the platelet lipids and on function by the cytoplasmic calcium concentration of the platelets exposed to increasing concentrations of 26-OH-CHOL for various periods of time. The intracellular free calcium (Ca2+)i of the gel-filtered rat platelets was monitored by a fluorescent probe (quin 2) after incubation in a 37 degrees C water bath with 1 mM Ca2+ and 20 microM quin 2/AM. The presence of 26-OH-CHOL in the incubation media changed both the phospholipid composition and the mixed fatty acid composition in the membrane and increased the intracellular free Ca2+ level of the platelets. As the incubation of platelets with cholesterol (CHOL) or esterified 26-OH-CHOL did not increase intracellular Ca2+ levels, these results indicate that the hydrophilic free 26-hydroxy group in 26-OH-CHOL may have influenced the enzymes catalyzing the synthesis of the phospholipid in the platelet membrane so as to allow it to become more and more "leaky" to Ca2+. Such a fundamental change in membrane structure and function may be responsible for the development of atherosclerosis in the intimal layer of the coronary arteries.