Increases in booster seat use among children of low income families and variation with age.

OBJECTIVES: To increase booster seat use among low income parents. DESIGN/METHODS: A pre-test/post-test design conducted in nine daycare centers with post-test observations four to eight weeks after the intervention. INTERVENTION: Parents who participated in an educational training received free seats, educational programs were provided to all daycare staff and children, and signs in parking lots informed parents about child restraints. At seven centers, new policies recommended compliance with state restraint laws. Parents at four centers randomly chosen from the seven received financial incentives if observed using booster seats. MAIN OUTCOME MEASURE: The percent of children aged 4-8 riding in booster seats. RESULTS: Pre-test observations of 185 4-8 year olds found 56% riding unrestrained and fewer than 3% riding in booster seats. After the intervention, observation of 146 children found the number riding in booster seats increased to 38% and the number observed without restraints decreased to 26%. Most booster seat use occurred with 4 and 5 year olds. No 7 or 8 year olds rode in booster seats. Changing center policies to recommend compliance with state restraint laws and an offer of financial incentives appeared to have no additional impact. CONCLUSIONS: Booster seat usage among low income families can be increased dramatically, though use decreases with age. Providing free seats accompanied by training may be sufficient without the need for additional intervention.

Simplified liquid-chromatographic determination of vancomycin.

We simplified determination of vancomycin in serum by using a direct and rapid solvent precipitation of protein and by using a simple organic compound as internal standard. Reproductibility of the vancomycin retention time was improved by modifying the mobile phase. Data obtained by fluorescence polarization immunoassay correlated well, and there was little bias between the two methods. The present method is sufficiently rapid to make this a practical choice for many laboratories.

The effect of cholesterol on glycerophosphono- and glycerophosphinocholines. Permeability measurements in lipid vesicles.

The kinetics of spontaneous chloride ion efflux and valinomycin-mediated rubidium-86 efflux from vesicles prepared from synthetic phospholipids with carbon-phosphorus linkages were investigated at temperatures above the gel-to-liquid-crystalline phase transition. The rate constants for the movement of chloride and rubidium ions were reduced by incorporation of cholesterol into bilayers of phosphono- and phosphinocholines. Nonisosteric phosphonolipids in which the oxygen was removed from the glycerol side of phosphorus without substitution by a methylene group interacted less with cholesterol than the analogous isosteric derivatives, as judged from the magnitude of the decrease in the rate constants for chloride and rubidium ion efflux. The experiments reported in this study suggest that steric factors in the glycerol side of the phosphorus function are important in phosphatidylcholine-cholesterol interaction. However, the oxygen atom on the choline side of the phosphorus in the phosphatidylcholine molecule is not required for strong phosphatidylcholine-cholesterol interaction, since isosteric glycerophosphinocholines interacted as well as the corresponding isosteric glycerophosphonocholines. Furthermore, steric requirements on the choline side of phosphorus are not important in this interaction since phosphinates whose head-group structures are -P(O-)CH2CH2N+(CH3)3 and -P(O-)CH2CH2CH2N+(CH3)3 interacted equally well with cholesterol, as estimated by these permeability studies.

Inhibition of platelet phosphatidylinositol synthetase by an analog of CDP-diacylglycerol.

Unpublished portions of the synthesis of a phosphinate-phosphonate diether analog of CDPdiacylglycerol are reported. The liponucleotide analog was found to be a very powerful inhibitor of platelet PI synthetase; kinetic data suggest a competitive inhibition mechanism. The structural specificity of CDPdiacylglycerol for liponucleotide-mediated biosynthetic reactions is discussed.

Cardiolipins are 'in vitro' inhibitors of rat brain (Na+ + K+)-dependent ATPases. A probable mechanism of action.

Cardiolipins were found to potentiate the 'in vitro' inhibitory activity of (-)-delta 9-tetrahydrocannabinol on (Na+ + K+)-dependent rat brain ATPases. The compounds were found to be powerful inhibitors by themselves. At optimal concentrations of cations (Na+, K+, Mg2+), the compounds were found to be noncompetitive inhibitors of ATP (Ki = 3.5 x 10(-6) M) and 'uncompetitive' inhibitors of Na+. From gas-liquid chromatographic analysis of the cardiolipin preparations it can be inferred that their effectiveness as inhibitors is related to the linoleic acid contents. The preliminary data presented here suggest that cardiolipins inhibit the Na+-dependent phosphorylation step in the hydrolysis of ATP. Based on the observations reported in this work, a hypothesis is presented suggesting that there may be a functional or evolutionary explanation for the paucity of cardiolipins in cell plasma membranes.

Synthesis of phosphonate and ether analogs of rac-phosphatidyl-L-serine.

The chemical synthesis of four phosphonate-containing phosphatidylserine analogs namely, L-serine (+/-)-[2,3-bis(hexadecyloxy) and 2,3-bis(Palmitoyloxy)-propyl] phosphonates, and L-serine (+/-)-[3,4-bis(hexadecyloxy and 3,4-bis(palmitoyloxy)-butyL]phosphonates is descirbed. (+/-)-2,3-Bis(hexadecyloxy) and 2,3-bis(palmitoyloxy)-prophylphosphonic acids and (+/-)-3,4-bis(hexadecyloxy)butylphosponic acid were prepared by reaction of tris(trimethylsily) phosphite on the corresponding haloalkane. Condensation of the above phosphonic acids or (+/-)-3,4-bis(palmitoyloxy)butylphosphonic acid with N-carboxy-L-serine dibenzyl ester in the presence of trichloroacetonitrile or triisopropylbenzenesulfonyl chloride yielded the protected serine intermediates, which on hydrogenolysis gave the desired L-serine analogs. By a similar route, 1,2-dihexadecyl-rac-glycero-3-phosphoric acid was converted to 1,2-dihexadecyl-rac-glycerophospho-L-serine (L-serine (+/-)-2,3-bis(hexadecyloxy)propyl hydrogen phosphate(ester).

Specificity of the phosphatidylcholine exchange protein from bovine liver.

The phosphatidylcholine exchange protein from bovine liver stimulates the specific transfer of phosphatidylcholine (PC) from rat liver microsomes to mitochondria or phospholipid vesicles (Wirtz, K.W.A., Kamp, H.H., and van Deenen, L.L.M. (1972), Biochim. Biophys. Acta 274, 606). In the present study, it has been established which components of the PC molecule are essential to the specific interaction with the protein. Radiochemically labeled analogues of PC have been synthesized with modifications in the polar and apolar moiety, and their transfer was measured between donor and acceptor vesicles. Relative to 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphorylcholine (egg yolk PC), transfer is inhibited or abolished when (a) the distance between phosphorus and nitrogen is decreased or increased and (b) a methyl group on the quaternary nitrogen is removed or substituted by an ethyl or propyl group. Transfer is much less affected when (a) the ester bonds are replaced by ether or carbon-carbon bonds, (b) the PC molecule contains two saturated fatty acids, and (c) the D stereoisomer is used. It is concluded that the protein has a binding site which interacts specifically with the phosphorylcholine head group and which cannot accommodate substantial configurational changes. Interaction with the apolar moiety of PC is less specific. However, lyso-PC is not transferred, suggesting that two hydrocarbon chains are required to stabilize the exchange protein-phospholipid complex. Interaction of [14C]PC-labeled exchange protein with vesicles of different phospholipid compositon has been analyzed by measuring the release of [14C]PC into these vesicles. Vesicles of egg PC or dimethylphosphatidylethanolamine function as acceptors, in contrast to vesicles of sphingomyelin or phosphatidylethanolamine.

Evaluation of enzyme-multiplied immunoassay technique (EMIT) for determination of serum digoxin.

Sixty-seven digoxin-containing sera were analyzed by both radioimmunoassay and EMIT. After some important modifications of the EMIT method, agreement between the two methods was very good. Reproducibility of the EMIT assay was excellent; daily variations in values found for control sera were quite small, and recovery of added digoxin was good. Slight hemolysis hadnegligible effects, but highly hemolyzed specimens gave low recoveries of digoxin.

Isosteres of natural phosphates. 4. The synthesis of phosphonic acid analogues of phosphatidic acid and acyldihydroxy acetone phosphate.

The chemical synthesis of 3,4-diacyloxybutyl-1-phosphonic acids having palmitoyl and oleoyl groups is described. These were prepared by reaction of the appropriate 3,4-diacyloxybutyl-1-bromide with tris(trimethylsilyl) phosphite followed by mild hydrolysis of the trimethyl-silyl groups from the phosphonic acid. Also reported is the preparation of 4-palmitoyl-3-oxobutyl-1-phosphonic acid by the acylation of 4-hydroxy-3-oxobutyl-1-phosphonic acid. This latter compound is an isosteric analogue of acyldihydroxyacetone phosphate.

Synthesis of DL-2,3-diacyloxypropylphosphonyl-cholines from DL-2,3-diacyloxyiodopropanes.

The chemical synthesis of racemic diacyloxypropylphosphonylcholines having octanoyl, myristoyl, oleoyl and stearoyl groups is described. The route involved reaction of dioactanoyloxy-dimyristoyloxy-dioleoyloxy-, and distearoyloxpropyliodide with tris (trimethylsilyl) phosphite to yield the corresponding bis (trimethylsilyl) phosphonate. Removal of the trimethylsilyl groups by neutral aqueous hydrolysis gave the free diacylpropylphosphonic acids, which, when treated with choline toluenesulfonate, yielded the desired dioctanoyloxy-, dimyristoyloxy-, dioleoyloxy-, and distearoyloxypropylphosphonylcholines. The paper also describes the synthesis of 2-octadecyleicosylphosphorylcholine.

Substrate activity of phosphonic acid analogues of CDPdiglyceride in the synthesis of phosphoglycerides in Escherichia coli.

Two phosphonic acid analogues of CDPdiglyceride, D L-2-hexadecoxy-3-octadecoxypropylphosphonyl-O-(cytidine 5'-phosphate) (analogue (I), and D L-3,4-dioctadecoxybutylphosphonyl-O-(cytidine 5'-phosphate) (analogue (II), have been synthesized and examined as substrates for the enzymes involved in the synthesis of phosphoglycerides in Escherichia coli. Both compounds were substrates for CDPdiglyceride:sn-glycerol-3-phosphate phosphatidyl transferase. The analogues had similar Km values (Km of 0.060 mM for analogue (II): Km of 0.080 mM for analogue (I) and a V identical to that of CDPdipalmitin (Km of 0.044 mM). In contrast, the analogues were poor substrates for CDPdiglyceride:L-serine phosphatidyl transferase. The analogues had lower Km values (Km of 0.40 mM for analogue (II); Km of 0.80 mM for analogue (I) than CDPdipalmitin (Km of 1.4 mM). The V, although identical for both analogues, was ten-fold lower than that observed with the natural substrate. An analysis of the products of these enzymatic reactions suggests that phosphatidylglycerophosphate phosphatase and phosphatidylserine decarboxylase may also possess a certain degree of substrate specificity.