Laser Doppler flowmetry for monitoring traumatized teeth

Laser Doppler Flowmetry (LDF) has been shown to be valuable in monitoring revascularization of immature incisors following severe dental trauma. Several investigators have demonstrated the ability of LDF to record blood flow signals from vital tooth pulps. In this case report, LDF was used for a 7-year-old child patient following a severe luxation of tooth #9. During follow-up examinations the traumatized tooth was unresponsive to traditional vitality testing during the first 6 months; however, LDF indicated that revascularization had occurred much sooner. Until recently, CO2 ice has been the most effective method for sensitivity testing in trauma cases such as presented here. In this case, LDF gave us the assurance that we could defer invasive care during a critical time period when root canal therapy might have been initiated for this child patient.

Early childhood caries: analysis of psychosocial and biological factors in a high-risk population

The influences that link social factors and caries development are not well understood, although mediation by stress has been suggested. The association between caregiver stress and early childhood caries (ECC), in particular, remains unclear. The purpose of this study was to examine the relationships between parenting stress and ECC while controlling for behavioral and biological factors in a high-risk population. One hundred and fifty healthy children aged 18-36 months were examined in a cross-sectional study design. Parental interviews were conducted to obtain demographic, oral health behavior and parenting stress data. Clinical data included parent and child bacterial measures, fingernail fluoride analyses, caries prevalence and presence of child enamel hypoplasia. Bivariate analyses revealed that parenting stress predicted caries. Multivariate analyses demonstrated that a combination of psychosocial, behavioral, temporal and biological variables predicted ECC outcomes. Total parenting stress did not contribute independently to the best prediction model. Our findings suggest the need for the development of a multidimensional stress model that considers the parent-child dyad to elucidate further the link between psychosocial factors and ECC.

Elongation of alternating alpha 2,8/2,9 polysialic acid by the Escherichia coli K92 polysialyltransferase

We have chosen E. coli K92, which produces the alternating structure alpha(2-8)neuNAc alpha(2-9)neuNAc as a model system for studying bacterial polysaccharide biosynthesis. We have shown that the polysialyltransferase encoded by the K92 neuS gene can synthesize both alpha(2-8) and alpha(2-9) neuNAc linkages in vivo by 13C-nuclear magnetic resonance analysis of polysaccharide isolated from a heterologous strain containing the K92 neuS gene. The K92 polysialyltransferase is associated with the membrane in lysates of cells harboring the neuS gene in expression vectors. Although the enzyme can transfer sialic acid to the nonreducing end of oligosaccharides with either linkage, it is unable to initiate chain synthesis without exogenously added polysialic acid. Thus, the polysialyltransferase encoded by neuS is not sufficient for de novo synthesis of polysaccharide but requires another membrane component for initiation. The acceptor specificity of this polysialyltransferase was studied using sialic acid oligosaccharides of various structures as exogenous acceptors. The enzyme can transfer to the nonreducing end of all bacteria polysialic acids, but has a definite preference for alpha(2-8) acceptors. Gangliosides containing neuNAc alpha(2-8)neuNAc are elongated, whereas monsialylated gangliosides are not. Disialylgangliosides are better acceptors than short oligosaccharides, suggesting a lipid-linked oligosaccharide may be preferred in the elongation reaction. These studies show that the K92 polysialyltransferase catalyzes an elongation reaction that involves transfer of sialic acid from CMP-sialic acid to the nonreducing end of two different acceptor substrates.

Cloning and expression of human sialic acid pathway genes to generate CMP-sialic acids in insect cells

The addition of sialic acid residues to glycoproteins can affect important protein properties including biological activity and in vivo circulatory half-life. For sialylation to occur, the donor sugar nucleotide cytidine monophospho-sialic acid (CMP-SA) must be generated and enzymatically transferred to an acceptor oligosaccharide. However, examination of insect cells grown in serum-free medium revealed negligible native levels of the most common sialic acid nucleotide, CMP-N-acetylneuraminic acid (CMP-Neu5Ac). To increase substrate levels, the enzymes of the metabolic pathway for CMP-SA synthesis have been engineered into insect cells using the baculovirus expression system. In this study, a human CMP-sialic acid synthase cDNA was identified and found to encode a protein with 94% identity to the murine homologue. The human CMP-sialic acid synthase (Cmp-Sas) is ubiquitously expressed in human cells from multiple tissues. When expressed in insect cells using the baculovirus vector, the encoded protein is functional and localizes to the nucleus as in mammalian cells. In addition, co-expression of Cmp-Sas with the recently cloned sialic acid phosphate synthase with N-acetylmannosamine feeding yields intracellular CMP-Neu5Ac levels 30 times higher than those observed in unsupplemented CHO cells. The absence of any one of these three components abolishes CMP-Neu5Ac production in vivo. However, when N-acetylmannosamine feeding is omitted, the sugar nucleotide form of deaminated Neu5Ac, CMP-2-keto-3-deoxy-D-glycero-D-galacto-nononic acid (CMP-KDN), is produced instead, indicating that alternative sialic acid glycoforms may eventually be possible in insect cells. The human CMP-SAS enzyme is also capable of CMP-N-glycolylneuraminic acid (CMP-Neu5Gc) synthesis when provided with the proper substrate. Engineering the CMP-SA metabolic pathway may be beneficial in various cell lines in which CMP-Neu5Ac production limits sialylation of glycoproteins or other glycans.

A cost analysis of treating pediatric dental patients using general anesthesia versus conscious sedation

The purpose of this pilot study is to report a cost comparison of general anesthesia (GA) versus oral conscious sedation (CS) for pediatric dental patients. The study sample included 22 children whose parents or guardians selected GA care for their child. Selection criteria limited inclusion to healthy children (American Society of Anesthesiologists' classification I) aged 24-60 months. The subjects acted as their own comparison group to an estimation CS model. Models were developed to assess societal costs for treatment under GA and CS. Treatment rendered was equalized using the dental relative based value unit scale.

Cloning and expression of the human N-acetylneuraminic acid phosphate synthase gene with 2-keto-3-deoxy-D-glycero- D-galacto-nononic acid biosynthetic ability

Sialic acids participate in many important biological recognition events, yet eukaryotic sialic acid biosynthetic genes are not well characterized. In this study, we have identified a novel human gene based on homology to the Escherichia coli sialic acid synthase gene (neuB). The human gene is ubiquitously expressed and encodes a 40-kDa enzyme. The gene partially restores sialic acid synthase activity in a neuB-negative mutant of E. coli and results in N-acetylneuraminic acid (Neu5Ac) and 2-keto-3-deoxy-D-glycero-D-galacto-nononic acid (KDN) production in insect cells upon recombinant baculovirus infection. In vitro the human enzyme uses N-acetylmannosamine 6-phosphate and mannose 6-phosphate as substrates to generate phosphorylated forms of Neu5Ac and KDN, respectively, but exhibits much higher activity toward the Neu5Ac phosphate product.

The physiological effects of supplemental oxygen versus nitrous oxide/oxygen during conscious sedation of pediatric dental patients

PURPOSE

This study was performed to compare the effects of nitrous oxide/oxygen (N2O/O2) versus oxygen (O2) as adjuncts to an oral narcotic regimen for pediatric conscious sedation.

METHODS

Using a randomized double-blind crossover design, 19 children (mean age 41 +/- 8.6 months) were sedated with chloral hydrate (50 mg/kg), meperidine (1.5 mg/kg) and hydroxyzine pamoate (25 mg) for two appointments. Patients were assigned randomly to receive 100% O2 at one visit and 50% N2O/O2 at the other. Physiologic parameters were measured in five-minute intervals, including respiratory rate, pulse rate (PR), oxyhemoglobin saturation (SpO2) and end-tidal carbon dioxide. Data analyses focused on true desaturations and apnea, level of sedation and sedation outcomes.

RESULTS

There were no differences in PR, SpO2 and risk of desaturation between the inhalation agents. The level of sedation was deeper and the sedation outcomes were better in the N2O/O2 group.

CONCLUSION

N2O/O2 deepened the sedation while improving its success with minimal alteration in physiologic parameters.

A cost analysis of treating pediatric dental patients using general anesthesia versus conscious sedation

PURPOSE

The purpose of this pilot study is to report a cost comparison of general anesthesia (GA) versus oral conscious sedation (CS) for the treatment of pediatric dental patients.

METHODS

The study sample included 22 children whose parents/guardian selected GA care for their child. Selection criteria limited inclusion to healthy children (ASA I) ages 24-60 m.o. The subjects acted as their own comparison group to an estimation CS model. Models were developed to assess societal costs for treatment under GA and CS. Treatment rendered was equalized using the dental Relative Based Value Units Scale (RBVU).

RESULTS

Ordinary Least Squares Regression analysis techniques showed the association of RBVU to the total societal costs of GA and CS to be significant (P < 0.01) with an adjusted R2 of .64 and .78 respectively. When regression lines were plotted, the intersection represented RBVU level at which societal costs of GA and CS were the same.

CONCLUSION

Under the conditions of this pilot study, it is concluded that CS costs exceed GA costs at a RBVU level of 66.4, which would equate to more than three CS appointments.

Identification of Arg-12 in the active site of Escherichia coli K1 CMP-sialic acid synthetase

Escherichia coli K1 CMP-sialic acid synthetase catalyses the synthesis of CMP-sialic acid from CTP and sialic acid. The active site of the 418 amino acid E. coli enzyme was localized to its N-terminal half. The bacterial CMP-sialic acid synthetase enzymes have a conserved motif, IAIIPARXXSKGLXXKN, at their N-termini. Several basic residues have been identified at or near the active site of the E. coli enzyme by chemical modification and site-directed mutagenesis. Only one of the lysines in the N-terminal motif, Lys-21, appears to be essential for activity. Mutation of Lys-21 in the N-terminal motif results in an inactive enzyme. Furthermore, Arg-12 of the N-terminal motif appears to be an active-site residue, based on the following evidence. Substituting Arg-12 with glycine or alanine resulted in inactive enzymes, indicating that this residue is required for enzymic activity. The Arg-12-->Lys mutant was partially active, demonstrating that a positive charge is required at this site. Steady-state kinetic analysis reveals changes in k(cat), K(m) and K(s) for CTP, which implicates Arg-12 in catalysis and substrate binding.

Purification of CMP-N-acetylneuraminic acid synthetase from bovine anterior pituitary glands

CMP-beta-N-acetylneuraminic acid (CMP-neuNAc) is the substrate for the sialylation of glycoconjugates by sialyltransferases in microbes and higher eukaryotes. CMP-neuNAc synthetase catalyzes the formation of this substrate, CMP-neuNAc, from CTP and neuNAc. In this report we describe the purification of CMP-neuNAc synthetase from bovine anterior pituitary glands. The enzyme was purified by ion exchange, gel filtration, and affinity chromatography. The protein was homogeneous on SDS-PAGE with a molecular weight of 52 kDa, a subunit size similar to that of the E.coli K1 (48.6 kDa). The identity of the 52 kDa protein band was confirmed by native gel electrophoresis in that the position of the enzyme activity in gel slices coincided with the position of major bands in the stained gel. Photoaffinity labeling with 125I-ASA-CDP ethanolamine resulted in the modification of a 52 kDa polypeptide that was partially protected against modification by the substrate CTP. Enzyme activity in crude fractions could be adsorbed onto an immunoadsorbent prepared from antibody against the purified 52 kDa protein. Taken together these data suggest that the 52 kDa polypeptide purified by this procedure described in this report is indeed CMP-neuNAc synthetase. The active enzyme chromatographed on a gel filtration column at 158 kDa suggesting it exists in its native form as an oligomer.

Covalent modification of Lys19 in the CTP binding site of cytidine 5'-monophosphate N-acetylneuraminic acid synthetase

Periodate oxidized CTP (oCTP) was used to investigate the importance of lysine residues in the CTP binding site of the cytidine 5'-monophosphate N-acetylneuraminic acid (CMP-NeuAc) synthetase (EC 2.7.7.43) from Haemophilus ducreyi. The reaction of oCTP with the enzyme follows pseudo-first-order saturation kinetics, giving a maximum rate of inactivation of 0.6 min(-1) and a K(I) of 6.0 mM at pH 7.1. Mass spectrometric analysis of the modified enzyme provided data that was consistent with beta-elimination of triphosphate after the reaction of oCTP with the enzyme. A fully reduced enzyme-oCTP conjugate, retaining the triphosphate moiety, was obtained by inclusion of NaBH3CN in the reaction solution. The beta-elimination product of oCTP reacted several times more rapidly with the enzyme compared to equivalent concentrations of oCTP. This compound also formed a stable reduced morpholino adduct with CMP-NeuAc synthetase when the reaction was conducted in the presence of NaBH3CN, and was found to be a useful lysine modifying reagent. The substrate CTP was capable of protecting the enzyme to a large degree from inactivation by oCTP and its beta-elimination product. Lys19, a residue conserved in CMP-NeuAc synthetases, was identified as being labeled with the beta-elimination product of oCTP.

Children's utilization of dental care in the NC Medicaid program

PURPOSE

To characterize the patterns of dental care in the North Carolina (NC) Medicaid Program for three- and eight-year-old children who began dental treatment in the 1985-86 and 1990-91 groups. We also compared the children's patterns of care by provider (general dentists versus pediatric dentists).

METHODS

Our extensive data set included claims, enrollment, and provider data. Children were assigned to one of five categories or patterns of care as follows: complete care, general anesthesia care, sporadic care, emergency only care, and no care. Statistical comparisons of the variables age, cohort year, and provider groups were made.

RESULTS

The use of Medicaid dental services by both age groups was severely limited in both yearly cohorts. Pediatric dentists tended to provide more complete and less sporadic care for both age groups and both yearly cohorts.

CONCLUSIONS

Financing dental care through Medicaid results in very low levels of complete care among enrollees, and any plan that limits referral to pediatric dentists might adversely affect the number of enrollees who receive complete care.

The effect of supplemental oxygen on apnea and oxygen saturation during pediatric conscious sedation

PURPOSE

This study compared the effect of supplemental oxygen (O2) on pediatric patients' apnea status and oxyhemoglobin saturation during: 1) conscious sedation for dental procedures and 2) the recovery period following sedation.

METHODS

Fourteen child patients (mean age 42 months) sedated with 50 mg/Kg chloral hydrate, 25 mg hydroxyzine pamoate, and 1.5 mg/Kg meperidine were treated for two separate appointments. The patients received supplemental O2 via nasal cannulae at random at one of the two appointments. Following the operative period, all patients were monitored sitting upright for an additional 15 min.

RESULTS

Intraoperative results showed that the risk of apnea was 39% (11/28), with apneic events distributed equally between O2 and non-O2 supplemented sedations. The overall risk of desaturation was 29% (8/28). Mean SpO2 was always elevated with O2 supplementation and the mean difference in O2 versus non-O2 was statistically significant. The risk of apnea in the postoperative period was 7% (1/14) for both the non-O2 and O2-supplemented patients. The risk of desaturation in the postoperative period was 11% (3/28) with one desaturation in a non-O2 and two desaturations in O2-supplemented patients.

CONCLUSION

We conclude that intraoperative O2 supplementation prevents desaturations even in the presence of apnea during pediatric conscious sedation.

Purification and characterization of the Escherichia coli K1 neuB gene product N-acetylneuraminic acid synthetase

Escherichia coli K1 produces a capsular polysaccharide of alpha(2-8) poly-N-acetylneuraminic acid. This polysaccharide is an essential virulence factor of these neuropathogenic bacteria. The genes necessary for the synthesis of neuNAc were localized to a plasmid containing the neuBAC genes of the K1 gene cluster. Cells harboring the neuB+ allele in an aldolase (nanA-) negative background produce neuNAc in vivo. Enzymatic synthesis of neuNAc could be demonstrated in extracts of cells harboring an expression plasmid (pNEUB) containing the neuB gene alone. NeuNAc synthetase was purified to homogeneity from extracts of cells harboring pNEUB. The molecular weight of the purified enzyme is 40 kDa, similar to that predicted by the nucleotide sequence of the neuB gene. The amino terminal sequence of the purified protein matches that predicted by the nucleotide sequence of the neuB gene. NeuNAc synthetase catalyzes the formation of neuNAc as indicated by its coupling to the CMP-neuNAc synthetase reaction. The enzyme condenses manNAc and PEP with the release of phosphate. The E. coli neuNAc synthetase is specific for manNAc and PEP, unlike rat liver enzyme that utilizes N-acetylmannosamine-6-phosphate to form neuNAc-9-PO4. This represents the first report of a purification of a sialic acid synthetase from either a eukaryotic or prokaryotic source to homogeneity. These experiments clearly demonstrate an aldolase-independent sialic acid synthetase activity in E. coli K1.

Pediatric and general dentists' participation in the North Carolina Medicaid program: trends from 1986 to 1992

The purpose of this study was to report trends in dentists' participation in the North Carolina Medicaid program. Medicaid claims files for dental users younger than age 21 were analyzed for seven fiscal years (FY) from 1986 to 1992. Over the study period, the number of pediatric dentists filing any Medicaid claims remained constant but the number of participating general dentists decreased slightly. Intensity of participation, as measured by mean annual reimbursement and mean number of children treated per dentist, increased from FY 89 to 92 for both provider groups. The mean value of services provided for each dental users also increased slightly during the same period. The data revealed over time pediatric dentists treated a larger proportion of the youngest Medicaid dental users.

Restoration of primary molars using a new "compomer" material

The primary advantages of glass ionomer restorative materials are adhesion to tooth structure and release of fluoride. A new material has been recently introduced for the restoration of cervical lesions and Class I defects in primary teeth. The material combines the properties of glass ionomers with the advantages of a single-component, light-activated composite resin and is known as a "compomer". This new material contains two resins, instead of the acidic polymers found in conventional glass ionomers. The restorative material releases fluoride and can be infected directly into the cavity. With its own bonding agent, the compomer offers a simple and relatively rapid technique. The learning objective of this paper is to describe the utilization of the new restorative material in conjunction with a bonding agent to restore conservative cavity preparations in primary molars. Two clinical cases are used to illustrate the presentation.

A comparison of conventional versus electronic monitoring of sedated pediatric dental patients

The first purpose of this study was to compare traditional monitoring methods to electronic instruments for monitoring physiologic parameters during conscious sedation of pediatric dental patients. Traditional methods included careful visual assessment of skin color, airway patency and chest movements, and auscultation of breath and heart sounds using a precordial stethoscope; electronic instruments included the capnograph and pulse oximeter. The second purpose of the study was to examine the potential of the capnograph to provide more advanced warning than the pulse oximeter for respiratory compromise. Thirty-nine children (mean age 39 months) received an oral sedative regimen of chloral hydrate, hydroxyzine pamoate, and meperidine and all were supplemented with 100% oxygen via nasal cannula throughout their sedations. One investigator used traditional monitoring and the other used electronic--both monitored simultaneously while being shielded (blinded) from each other. Electronic monitoring yielded a false alert rate of 88% compared with 73% for traditional monitoring. Ten confirmed episodes of respiratory compromise were identified electronically and only three were identified by traditional monitoring. All of the 10 confirmed respiratory compromise episodes were detected by capnography; none were detected by oximetry. During these 39 pediatric sedations using a narcotic drug regimen and 100% oxygen supplementation, there were no true desaturations.