Expression of leucine-rich repeats and immunoglobulin-like domains (LRIG) proteins in human ependymoma relates to tumor location, WHO grade, and patient age.

Three human leucine-rich repeats and immunoglobulin-like domains (LRIG1-3) genes and proteins have recently been characterized. LRIG1 has been shown to be a suppressor of tumor growth by counteracting the signaling of epidermal growth factor receptor (EGFR) family members, including EGFR (ERBB1). Expression of LRIG proteins seems to be of importance in the pathogenesis of astrocytic tumors. In this study, the expression of LRIG1-3 was evaluated in 51 human ependymomas by immunohistochemistry. LRIG proteins were detected in all ependymomas analyzed, however, with a pronounced heterogeneity in expression and subcellular localization. Higher cytoplasmic immunoreactivity of LRIG1 correlated with older patient age and higher LRIG1 nuclear immunoreactivity with lower WHO Grade. LRIG1 displayed a stronger immunoreactivity in the cytoplasm and nuclei in spinal ependymomas than in the posterior fossa or supratentorial ependymomas, while perinuclear LRIG3 was more highly expressed in supratentorial than in infratentorial ependymomas. The indications that expression and subcellular localization of LRIG proteins could be pathogenetically associated with specific clinicopathological features of ependymoma tumors might be of importance in the carcinogeneses and tumor progression of human ependymomas.

Composition and dynamics of plasma in Saturn's magnetosphere.

During Cassini's initial orbit, we observed a dynamic magnetosphere composed primarily of a complex mixture of water-derived atomic and molecular ions. We have identified four distinct regions characterized by differences in both bulk plasma properties and ion composition. Protons are the dominant species outside about 9 RS (where RS is the radial distance from the center of Saturn), whereas inside, the plasma consists primarily of a corotating comet-like mix of water-derived ions with approximately 3% N+. Over the A and B rings, we found an ionosphere in which O2+ and O+ are dominant, which suggests the possible existence of a layer of O2 gas similar to the atmospheres of Europa and Ganymede.

Caries incidence and lesion progression from adolescence to young adulthood: a prospective 15-year cohort study in Sweden.

The objectives were (1) to assess caries development, including the incidence and rate of lesion progression, in a Swedish cohort from adolescence to young adulthood and (2) to compare the caries incidence rates in adolescents with those of young adults. The original material consisted of 536 children aged 11-13 years at baseline. This cohort had been followed through annual bitewing radiographs to 21-22 years of age. In 1998-1999, 250 of these individuals were re-examined at the age of 26-27, and the new caries data were added to the original data. The results showed that fewer new enamel lesions developed on approximal surfaces during young adulthood than during adolescence; the caries incidence rates for enamel lesions decreased from 4.3 in the age group 12-15 years to 2.7 new caries lesions/100 surface-years in the age group 20-27 years. The same applied to the rate of lesion progression, where the corresponding values from the enamel-dentin border to the outer dentin were 32.5 for the youngest and 10.9 new lesions/100 surface-years for the oldest age group. The caries incidence of outer dentin lesions on approximal surfaces was low but increased from 0.2 in the age group 12-15 years to 0.9 new outer dentin lesions/100 surface-years in the age group 20-27 years. The incidence rates varied considerably between different tooth surfaces. Also for occlusal surfaces, fewer new dentin lesions developed during young adulthood than during adolescence; the incidence was 2.0 new dentin lesions/100 surface-years in the youngest age group and 0.7 during young adulthood. At the age of 13, the proportion of DFS of occlusal surfaces predominated over DFS of approximal surfaces but at the age of 26-27 the proportions of occlusal and approximal DFS were almost equal.

Identification in Tetrahymena pyriformis of 3-hydroxy-3-methyl glutaryl coenzyme a lyase: its purification and properties.

The major HMG-CoA utilizing enzyme activity in T. pyriformis has been determined to be HMG-CoA lyase. The enzyme was purified 32-fold to a specific activity of 431 units/mg from a mitochondrial fraction. Sephacryl S-200 chromatography gave an estimated molecular weight of 50,000 daltons for the HMG-CoA lyase. SDS gel electrophoresis revealed two bands stained by Coomassie Blue--a major band of 50,000 daltons and a minor band of 25,000 daltons. The latter is believed to be an impurity in the preparation. The enzyme has a pH optimum of 9.0, is stimulated slightly by sulfhydryl reagents, and requires a divalent cation for maximum activity. The KM for HMG-CoA is 15 microM.

The effect of AY-9944 on yeast sterol and sterol ester metabolism.

The effects of the hypocholesterolemic drug AY-9944 (trans-1,4-bis(2-chlorobenzylaminoethyl)cyclohexane dihydrochloride) at two concentrations (10(-4) M and 5 X 10(-4) M) on the synthesis of sterols and sterol esters by Saccharomyces cerevisiae were investigated. Although growth was not markedly affected by the drug, there was a decrease in the free sterol to sterol ester ratio with increased drug concentration. A concomitant increase in the saturated fatty acids esterified to sterol relative to the unsaturated fatty acids was also noted in response to increased drug concentration. Ergosterol accounted for 94.7% of the free sterol in the control culture and for 87.8% of the 5 X 10(-4) M drug-treated culture, respectively. However, in the sterol ester fraction, the ergosterol content decreased from a value of 45.1% in the control culture to 2.4% in the 5 X 10(-4) M AY-9944 treated culture. The sterol ester fraction simultaneously showed increased levels of the delta 8 sterol, fecosterol, in response to increased drug concentration from a 7.4% control value to 57.4% in the 5 X 10(-4) M drug-treated culture. The accumulation of the delta 8 sterol suggests that the site of action of the drug is probably at the delta 8 to delta 7 isomerase step in the biosynthesis of ergosterol. The fact that ergosterol is retained as the major free sterol suggests a biological advantage to the retention of this particular sterol. In addition, the near normal growth in the presence of the drug, in spite of the occurrence of an altered sterol ester profile, indicates that the composition of the sterol ester fraction is not as critical as the free sterol fraction.

Purification and kinetic characterization of a specific glucokinase from Streptococcus mutans OMZ70 cells.

Glucokinase (ATP-D-glucose 6-phosphotransferase, EC 2.7.1.2) was purified 144-fold from extracts of sucrose-grown Streptococcus mutans OMZ70 (ATCC 33535) cells. Twenty compounds were tested as potential substrates; only glucose (Km = 0.61 mM) was phosphorylated. The reaction catalyzed by the purified enzyme was dependent on the presence of glucose, nucleoside triphosphate and metal ion; glucose 6-phosphate and ADP were the products. Of the seven nucleoside triphosphates tested, ATP (Km = 0.21 mM) was the most efficient phosphate donor in the enzyme-catalyzed formation of glucose 6-phosphate. Both Mn2+ (relative activity, 173%) and Co2+ (264%) were more efficient than Mg2+ (100%) in supporting the enzyme reaction. The enzyme exhibited a broad maximal activity in the pH range from 7.5 to 9.5. The apparent molecular weight of glucokinase, as determined by gel filtration, was 41 000. With glucose held constant at either saturating or subsaturating levels, ADP was a noncompetitive inhibitor of ATP (Ki = 0.67 mM). ADP was an uncompetitive inhibitor of glucose (Ki = 0.71 mM) when ATP was held constant at either a saturating or subsaturating concentration. Glucose 6-phosphate was a competitive inhibitor of glucose (Ki = 0.31 mM) at saturating ATP and exhibited noncompetitive or mixed inhibition at a subsaturating ATP concentration. Glucose 6-phosphate was not an inhibitor toward ATP at saturating glucose concentrations, but exhibited noncompetitive inhibition at subsaturating glucose concentrations. The kinetic data support the postulation of a sequential mechanism for the glucokinase reaction; they are consistent with an ordered mechanism in which glucose binds first and glucose 6-phosphate dissociates last. Furthermore, the data suggest the existence of more than one enzyme binding site for the substrates of the glucokinase reaction.

Effect of riboflavon analogs on the growth of Tetrahymena pyriformis.

Several analogs of riboflavin differing with respect to the substituent at C7, C8 or C10 were examined for their ability to replace riboflavin and to act as riboflavin antagonists in inhibiting growth of Tetrahymena pyriformis. Generally, the analogs with altered substituents at C7 or C8 (the 8-ethyl, 7,8-diethyl, 7-chloro and 8-chloro analogs) supported some growth but inhibited riboflavin-supported growth. However, the 8-bromo analog had no biological activity. The 7-ethyl analog with a bis(2-hydroxyethyl)aminoethyl side chain was the most potent antagonist. These results were compared with those observed in Lactobacillus casei and the rat.

Partial purification and properties of a mannofructokinase from Streptococcus mutans SL-1.

Fructokinase activity was demonstrated in seven strains of oral streptococci. The enzyme purified from Streptococcus mutans SL-1 was capable of phosphorylating both D-fructose and D-mmannose to their respective 6-phosphates. Phosphorylation of both fructose and mannose was dependent on adenosine 5'-triphosphate and a divalent metal ion. The molecular weight of the purified enzyme was estimated to be 49,000. The apparent Km of the enzyme for fructose was 0.63 mM. This enzyme also utilized mannose as a substrate, with an apparent Km for mannose of 0.37 mM. Since the activities of the enzyme toward mannose and fructose were not separated upon purification of the enzyme and since mannose was a competitive inhibitor of fructose phosphorylation, the purified kinase is a single enzyme, mannofructokinase, with dual specificity for both mannose and fructose. A role for this enzyme in carbohydrate metabolism in S. mutans is postulated.

Partial purification and properties of a specific glucokinase from Streptococcus mutans SL-1.

The presence of glucokinase (ATP:D-glucose 6-phosphotransferase, EC 2.7.1.2) activity in seven strains of oral streptococci is demonstrated. The glucokinase purified from Streptococcus mutans SL-1 cells is shown to be a highly specific enzyme, phosphorylating only glucose (eight sugars tested). The enzyme is a true glucokinase: formation of the product, shown here to be glucose 6-phosphate, is dependent on the presence of glucose, ATP, divalent metal ion and enzyme. The Km for glucose is 1.40 mM, the pH optimum for the enzyme is a broad plateu from pH 7.1 to 9.5 and the molecular weight is estimated to be 40 000. The finding of a glucokinase in oral streptococci indicates the existence of an intracellular mechanism of glucose phosphorylation. The implications of this observation are discussed.

The effects of the hypocholesteremic compound 3 beta-(beta-dimethylaminoethoxy)-androst-5-en-17-one on the sterol and steryl ester composition of Saccharomyces cerevisiae.

When yeast was grown in the presence of 10(-4) M 3 beta-(beta-dimethylaminoethoxy)-androst-5-en-17-one (DMAE-DHA), the compound 2,3;22,23-dioxidosqualene (DOS) accumulated. Total free sterol was reduced by about 30%, whereas almost no steryl esters were found. The same drug at lower concentration (3 x 10(-6) M) caused a slight increase in steryl ester production, and a 24% reduction in free sterol content. The marked accumulation of ergostra-5,7,22,24(28)-tetraen-3 beta-ol with 3 x 10(-6) M DMAE-DHA indicated that the C24-28 reductase is especially sensitive to the action of the drug.

Evaluation of a regional resource center for multiply handicapped retarded children.

A modified before--after, control-group evaluation design was employed to assess the impact of a demonstration program for multiply handicapped retarded children. Child development, parent and therapist attitudes, and knowledge and use of services were evaluated. Findings revealed no significant positive impact of the program on development, attitudes, and knowledge; the treatment group used more services. A significant change to a more negative attitude on the part of the treatment-group parents with regard to some aspects of normalization was found. Major impact of the program was in the area of coordination of services.

Effects of the hypocholesteremic agent trifluperidol on the sterol, steryl ester, and fatty acid metabolism of Saccharomyces cerevisiae.

Trifluperidol (TFP), at a concentration of 100 muM, inhibited the 24-h growth of Saccharomyces cerevisiae by about 30%. Effects on lipid metabolism were investigated by monitoring the incorporation of [1-14C]sodium acetate into various lipid fractions after 4 and 24 h of growth in the presence of several concentrations of TFP. Although little effect was noted on the amount of free sterols, 24-h incorporation of label into steryl esters was increased two- to fourfold by 100 muM TFP. Major sterol components of the steryl ester fraction isolated from an untreated culture were zymosterol (48%) and ergosterol (24%), whereas from the TFP-treated culture delta8,24(28)-ergostadienol (66.6%) and delta8-ergostenol (14.7%) were most abundant. Free sterols present in the highest concentration in the untreated culture were ergosterol (78.2%) and lanosterol (13%); whereas delta8,22-ergostadienol (38.5%), delta8-ergostenol (35.4%), and delta8,24(28)-ergostadienol (25.4%) were the most abundant free sterols obtained from the TFP-treated culture. Thus, the major block in the sterol biosynthetic pathway in yeast appears to be delta8 leads to delta7 isomerization. In these same cultures the relative amounts of C12 and C14 acids isolated from both steryl ester and miscellaneous lipid fractions were increased more than threefold over controls.

Inhibtion of diplopterol synthesis in Tetrahymena pyriformis by a hypocholesteremic compound.

The hypocholesteremic compound, 3beta-(beta-dimethylaminoethoxy)-androst-5-en-17-one was earlier shown to inhibit the synthesis of tetrahymanol and two undentified lipids. It now has been demonstrated that one of the unidentified compounds is diplopterol.

Identification of wax esters inTetrahymena pyriformis.

Wax esters, isolated fromTetrahymena pyriformis, have been found to contain 45% branched chain alcohols and 76% branched chain fatty acids. No esters of tetrahymanol or of sterols were found.