A Contemporary Examination of First and Second Permanent Molar Emergence

The emergence of first permanent molars (FPMs) and second permanent molars (SPMs) is an important developmental milestone influencing caries risk and the timing of sealant placement. Emergence times have been shown to vary by sex and race/ethnicity, while recent reports suggest a positive association with adiposity. Amid the changing demographics of the US population and the rising rates of pediatric overweight/obesity, we sought to examine the association of body mass index (BMI) with FPM/SPM emergence in a representative sample of US children and adolescents. We used cross-sectional data from 3 consecutive cycles of the National Health and Nutrition Examination Survey (2009 to 2014). The FPM analysis included ages 4 to 8 y ( n = 3,102 representing ~20 million children), and the SPM analysis included ages 9 to 13 y ( n = 2,774 representing ~19 million children/adolescents). The Centers for Disease Control and Prevention's growth chart data were used to calculate age- and sex-specific BMI percentiles, as measures of adiposity. Initial data analyses relied on descriptive statistics and stratified analyses. We used multivariate methods, including survey linear and ordinal logistic regression and marginal effects estimation to quantify the association between pediatric overweight/obesity and FPM/SPM emergence, adjusting for age, sex, and race/ethnicity. Forty-eight percent of 6-y-olds and 98% of 8-y-olds had all FPMs emerged, whereas SPM emergence varied more. Blacks (vs. whites) and females (vs. males) experienced earlier emergence of FPMs and SPMs. Overweight/obesity was associated with earlier FPM emergence, particularly among black females. Obesity but not overweight was associated with earlier SPM emergence. Overall, overweight/obesity accounted for 6 to 12 mo of dental acceleration. This study's results emanate from the most recent US-representative data and affirm that FPM/SPM emergence varies by race/ethnicity and sex and is positively influenced by BMI. Future research should further elucidate these associations with detailed eruption data and examine the implications of this variation for clinical care.

Addressing Selection Bias in Dental Health Services Research

When randomization is not possible, researchers must control for non-random assignment to experimental groups. One technique for statistical adjustment for non-random assignment is through the use of a two-stage analytical technique. The purpose of this study was to demonstrate the use of this technique to control for selection bias in examining the effects of the The Supplemental Program for Women, Infants, and Children’s (WIC) on dental visits. From 5 data sources, an analysis file was constructed for 49,512 children ages 1–5 years. The two-stage technique was used to control for selection bias in WIC participation, the potentially endogenous variable. Specification tests showed that WIC participation was not random and that selection bias was present. The effects of the WIC on dental use differed by 36% after adjustment for selection bias by means of the two-stage technique. This technique can be used to control for potential selection bias in dental research when randomization is not possible.

Is Dental Utilization Associated with Oral Health Literacy?

The objectives of this study were to examine the pattern of association between dental utilization and oral health literacy (OHL). As part of the Carolina Oral Health Literacy Project, clients in the Women, Infants, and Children's Special Supplemental Nutrition Program completed a structured 30-min in-person interview conducted by 2 trained interviewers at 9 sites in 7 counties in North Carolina. Data were collected on clients' OHL, sociodemographics, dental utilization, self-efficacy, and dental knowledge. The outcome, OHL, was measured with a dental word recognition test (30-item Rapid Estimate of Adult Literacy in Dentistry). Descriptive and multiple linear regression methods were used to examine the distribution of OHL and its association with covariates. After adjusting for age, education, race, marital status, self-efficacy, and dental knowledge, multiple linear regression showed that dental utilization was not a significant predictor of OHL (P > 0.05). Under the conditions of this study, dental utilization was not a significant predictor of OHL.

Evaluation in mice of a conjugate vaccine for cholera made from Vibrio cholerae O1 (Ogawa) O-specific polysaccharide

Background

Protective immunity against cholera is serogroup specific. Serogroup specificity in Vibrio cholerae is determined by the O-specific polysaccharide (OSP) of lipopolysaccharide (LPS). Generally, polysaccharides are poorly immunogenic, especially in young children.

Methodology

Here we report the evaluation in mice of a conjugate vaccine for cholera (OSP:TThc) made from V. cholerae O1 Ogawa O-Specific Polysaccharide–core (OSP) and recombinant tetanus toxoid heavy chain fragment (TThc). We immunized mice intramuscularly on days 0, 21, and 42 with OSP:TThc or OSP only, with or without dmLT, a non-toxigenic immunoadjuvant derived from heat labile toxin of Escherichia coli.

Principal Findings

We detected significant serum IgG antibody responses targeting OSP following a single immunization in mice receiving OSP:TThc with or without adjuvant. Anti-LPS IgG responses were detected following a second immunization in these cohorts. No anti-OSP or anti-LPS IgG responses were detected at any time in animals receiving un-conjugated OSP with or without immunoadjuvant, and in animals receiving immunoadjuvant alone. Responses were highest following immunization with adjuvant. Serum anti-OSP IgM responses were detected in mice receiving OSP:TThc with or without immunoadjuvant, and in mice receiving unconjugated OSP. Serum anti-LPS IgM and vibriocidal responses were detected in all vaccine cohorts except in mice receiving immunoadjuvant alone. No significant IgA anti-OSP or anti-LPS responses developed in any group. Administration of OSP:TThc and adjuvant also induced memory B cell responses targeting OSP and resulted in 95% protective efficacy in a mouse lethality cholera challenge model.

Conclusion

We describe a protectively immunogenic cholera conjugate in mice. Development of a cholera conjugate vaccine could assist in inducing long-term protective immunity, especially in young children who respond poorly to polysaccharide antigens.

Cholera is a severe dehydrating diarrheal illness of humans caused by organisms Vibrio cholerae serogroups O1 or O139 serogroup organisms. Protective immunity against cholera is serogroup specific. Serogroup specificity in V. cholerae is determined by the O-specific polysaccharide (OSP) of lipopolysaccharide (LPS). Generally, polysaccharides are poorly immunogenic, especially in young children. Unfortunately, children bear a large burden of cholera globally. Here we describe a novel cholera conjugate vaccine and show that it induces immune responses in mice, including memory responses, to OSP, the T cell-independent antigen that probably is the target of protective immunity to cholera. These responses were highest following immunization of the vaccine with a novel immunoadjuvant, dmLT. We also show that immunization of mice with this conjugate vaccine protects against challenge with wild-type V. cholerae. A protectively immunogenic cholera conjugate vaccine that induces long-term memory responses could have particular utility in young children who are most at risk of cholera.

Caregivers' health literacy and their young children's oral-health-related expenditures

Caregivers' health literacy has emerged as an important determinant of young children's health care and outcomes. We examined the hypothesis that caregivers' health literacy influences children's oral-health-care-related expenditures. This was a prospective cohort study of 1,132 child/caregiver dyads (children's mean age = 19 months), participating in the Carolina Oral Health Literacy Project. Health literacy was measured by the REALD-30 (word recognition based) and NVS (comprehension based) instruments. Follow-up data included child Medicaid claims for CY2008-10. We quantified expenditures using annualized 2010 fee-adjusted Medicaid-paid dollars for oral-health-related visits involving preventive, restorative, and emergency care. We used descriptive, bivariate, and multivariate statistical methods based on generalized gamma models. Mean oral-health-related annual expenditures totaled $203: preventive--$81, restorative--$99, and emergency care--$22. Among children who received services, mean expenditures were: emergency hospital-based--$1282, preventive--$106, and restorative care--$343. Caregivers' low literacy in the oral health context was associated with a statistically non-significant increase in total expenditures (average annual difference = $40; 95% confidence interval, -32, 111). Nevertheless, with both instruments, emergency dental care expenditures were consistently elevated among children of low-literacy caregivers. These findings provide initial support for health literacy as an important determinant of the meaningful use and cost of oral health care.

Oral health literacy among female caregivers: impact on oral health outcomes in early childhood

The aim of this study was to investigate the association of female caregivers' oral health literacy with their knowledge, behaviors, and the reported oral health status of their young children. Data on caregivers' literacy, knowledge, behaviors, and children's oral health status were used from structured interviews with 1158 caregiver/child dyads from a low-income population. Literacy was measured with REALD-30. Caregivers' and children's median ages were 25 yrs (range = 17-65) and 15 mos (range = 1-59), respectively. The mean literacy score was 15.8 (SD = 5.3; range = 1-30). Adjusted for age, education, and number of children, low literacy scores (< 13 REALD-30) were associated with decreased knowledge (OR = 1.86; 95% CI = 1.41, 2.45) and poorer reported oral health status (OR = 1.44; 95% CI = 1.02, 2.05). Lower caregiver literacy was associated with deleterious oral health behaviors, including nighttime bottle use and no daily brushing/cleaning. Caregiver oral health literacy has a multidimensional impact on reported oral health outcomes in infants and young children.

Adverse events and outcomes of conscious sedation for pediatric patients: study of an oral sedation regimen

BACKGROUND

The authors report on adverse events and sedation outcomes for an oral sedation regimen of chloral hydrate, meperidine and hydroxyzine with 100 percent oxygen, or O2, supplementation.

METHODS

In a five-year retrospective study, the authors examined 195 records of conscious sedation performed in 111 healthy children aged 24 to 48 months (mean, 47 months). The authors analyzed age, sex, weight, methods of drug delivery, waiting time after drug administration, treatment rendered, treatment time, adverse events, sedation outcomes and the number of visits needed to complete treatment using descriptive statistics, chi 2 tests, t test and analysis of variance.

RESULTS

Adverse events--including vomiting, desaturation, prolonged sedation and an apneic event--occurred in 3 percent of all sedations and were minor. Seventy-two percent of sedations had satisfactory behavioral outcomes, 23 percent had unsatisfactory outcomes, and 5 percent of the cases were aborted because of disruptive behavior. Sex was not a significant factor for the success. Patient compliance with drinking medications (P = .013) and a longer waiting time after medication intake (P = .012) yielded better sedation outcomes.

CONCLUSIONS

Minimal minor adverse events occurred with this sedation regimen. The success rate was 72 percent. Compliance with taking oral medications and waiting time appeared to be important factors in predicting sedation success.

CLINICAL IMPLICATIONS

This oral sedation regimen offers reasonable outcomes with minimal adverse events under a strict protocol and use of O2 supplementation. The results also revealed associations that give guidance for case selection and outcome prediction.

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.

Nucleotide sequence and genetic analysis of the neuD and neuB genes in region 2 of the polysialic acid gene cluster of Escherichia coli K1

The K1 capsular polysaccharide, a polymer of sialic acid, is an important virulence determinant of extraintestinal pathogenic Escherichia coli. The genes responsible for the synthesis and expression of the polysialic acid capsule of E. coli K1 are located on the 17-kb kps gene cluster, which is functionally divided into three regions. Central region 2 encodes proteins necessary for the synthesis, activation, and polymerization of sialic acid, while flanking regions 1 and 3 are involved in polymer transport to the cell surface. In this study, we identified two genes at the proximal end of region 2, neuD and neuB, which encode proteins with predicted sizes of 22.7 and 38.7 kDa, respectively. Several observations suggest that the neuB gene encodes sialic acid synthase. EV24, a neuB chromosomal mutant that expresses a capsule when provided exogenous sialic acid, could be complemented in trans by the cloned neuB gene. In addition, NeuB has significant sequence similarity to the product of the cpsB gene of Neisseria meningitidis group B, which is postulated to encode sialic acid synthase. We also present data indicating that neuD has an essential role in K1 polymer production. Cells harboring pSR426, which contains all of region 2 but lacks region 1 and 3 genes, produce an intracellular polymer. In contrast, no polymer accumulated in cells carrying a derivative of pSR426 lacking a functional neuD gene. Unlike strains with mutations in neuB, however, neuD mutants are not complemented by exogenous sialic acid, suggesting that NeuD is not involved in sialic acid synthesis. Additionally, cells harboring a mutation in neuD accumulated sialic acid and CMP-sialic acid. We also found no significant differences between the endogenous and exogenous sialyltransferase activities of a neuD mutant and the wild-type organism. NeuD shows significant similarity to a family of bacterial acetyltransferases, leading to the theory that NeuD is an acetyltransferase which may exert its influences through modification of other region 2 proteins.

Molecular cloning and analysis of genes for sialic acid synthesis in Neisseria meningitidis group B and purification of the meningococcal CMP-NeuNAc synthetase enzyme

The gene encoding for the CMP-NeuNAc synthetase enzyme of Neisseria meningitidis group B was cloned by complementation of a mutant of Escherichia coli defective for this enzyme. The gene (neuA) was isolated on a 4.1-kb fragment of meningococcal chromosomal DNA. Determination of the nucleotide sequence of this fragment revealed the presence of three genes, termed neuA, neuB, and neuC, organized in a single operon. The presence of a truncated ctrA gene at one end of the cloned DNA and a truncated gene encoding for the meningococcal sialyltransferase at the other confirmed that the cloned DNA corresponded to region A and part of region C of the meningococcal capsule gene cluster. The predicted amino acid sequence of the meningococcal NeuA protein was 57% homologous to that of NeuA, the CMP-NeuNAc synthetase encoded by E. coli K1. The predicted molecular mass of meningococcal NeuA protein was 24.8 kDa, which was 6 kDa larger than that formerly predicted (U. Edwards and M. Frosch, FEMS Microbiol. Lett. 96:161-166, 1992). Purification of the recombinant meningococcal NeuA protein together with determination of the N-terminal amino acid sequence confirmed that this 24.8-kDa protein was indeed the meningococcal CMP-NeuNAc synthetase. The predicted amino acid sequences of the two other encoded proteins were homologous to those of the NeuC and NeuB proteins of E. coli K1, two proteins involved in the synthesis of NeuNAc. These results indicate that common steps exist in the biosynthesis of NeuNAc in these two microorganisms.

Distribution of primary tooth caries in first-grade children from two nonfluoridated US communities

In a prospective longitudinal study, 1099 first grade children from Aiken, South Carolina, and 1086 children from Portland, Maine, were examined annually for 3 years. Caries prevalence and dmfs incidence were determined. The mean dmfs in Portland children was 2.9. In Aiken, white children had a mean dmfs of 8.4, and black children had a mean dmfs of 10.2. The mean 3-year primary tooth caries increment was 1.5 surfaces in the Portland cohort 3.3 surfaces in the Aiken white cohort and 2.8 surfaces in the Aiken black cohort. These increments were divided evenly between interproximal and fissure surfaces. Twenty percent of the children in Portland had 75% of the caries; in Aiken, 20% of the children had 60% of the caries. This distribution suggests a high-risk group that could be targeted for aggressive caries prevention efforts if risk factors can be identified.

The role of cysteine residues 129 and 329 in Escherichia coli K1 CMP-NeuAc synthase

N-Acetylneuraminic acid cytidyltransferase (CMP-NeuAc synthase) of Escherichia coli K1 is sensitive to mercurials and has cysteine residues only at positions 129 and 329. The role of these residues in the catalytic activity and structure of the protein has been investigated by site-directed mutagenesis and chemical modification. The enzyme is inactivated by the thiol-specific reagent dithiodipyridine. Inactivation by this reagent is decreased in the presence of the nucleotide substrate CTP, suggesting that a thiol residue is at or near the active site. Site-directed mutagenesis of either residue Cys-129 to serine or Cys-329 to selected amino acids has minor effects on the specific activity of the enzyme, suggesting that cysteine is not essential for catalysis and that a disulphide bond is not an essential structural component. The limited reactivity of the enzyme to other thiol-blocking reagents suggests that its cysteine residues are partially exposed. The accessibility and role of the cysteine residues in enzyme structure were investigated by fluorescence, c.d. and denaturation studies of wild-type and mutant enzymes. The mutation of Cys-129 to serine makes the enzyme more sensitive to heat and chemical denaturation, but does not cause gross changes in the protein structure as judged by the c.d. spectrum. The mutant containing Ser-129 instead of Cys-129 had a complex denaturation pathway similar to that of wild-type E. coli K1 CMP-NeuAc synthase consisting of several partially denatured states. Cys-329 reacts more readily with N-[14C]ethylmaleimide when the enzyme is in a heat-induced relaxed state. Cys-129 is less reactive and is probably a buried residue.

Pediatric dentists' participation in the North Carolina Medicaid program

Data on Medicaid participation by dentists in North Carolina were obtained from the North Carolina Division of Medical Assistance and through a survey of pediatric dentists. As a group, pediatric dentists were the most active participants in the North Carolina Medicaid program during the 1990-91 state fiscal year and provided a disproportionate share of treatment for Medicaid-eligible children. Seventy-five per cent of the pediatric dentists limit their Medicaid participation. Top reasons given for limiting access for new Medicaid patients included low reimbursement rates, broken or canceled appointments, and need for prior authorization of Medicaid treatment plans. This paper explores several critical issues regarding access to dental care for children served by the Medicaid program in North Carolina.

Identification of variable region differences in Neisseria meningitidis class 3 protein sequences among five group B serotypes

Strains of Neisseria meningitidis express one of two porin proteins. These porins have been identified as the class 2 and class 3 proteins, and express serotype-specific epitopes. The gene for the class 3 protein was amplified by the polymerase chain reaction from the DNA of a serotype 4 strain as a 1025 bp fragment. The nucleotide sequence of this gene was determined and compared with two recently published sequences. On the basis of this comparison we have identified two major variable regions in the translated protein sequence, VR1 and VR2, that may be associated with serotype specificity. Three other variable regions were also identified. The sequences in the VR1 and VR2 regions from five additional group B N. meningitidis strains of serotypes 1, 4, 8, 12, and 15, all expressing class 3 proteins, were determined. The VR1 and VR2 regions were variable and were flanked by highly conserved regions among eight different class 3 sequences. These two variable regions of 15 and 9 amino acids are predicted to be in surface-exposed loops.

Two natal maxillary molars. Report of a case

A 20-day-old black male infant with two rare posterior natal teeth was referred for examination and care. Oral radiographs suggested that the teeth were the right and left maxillary primary molars. The hypermobile teeth and associated suspicious soft tissue masses were removed. Histologic examination revealed irregular tooth structures and infiltrate consistent with inflamed dental follicles.

13C NMR investigation of the anomeric specificity of CMP-N-acetylneuraminic acid synthetase from Escherichia coli

The anomeric specificity of Escherichia coli CMP-N-acetylneuraminic acid (CMP-NeuAc) synthetase was investigated by NMR using 13C-labeled N-acetylneuraminic acid (NeuAc). Consumption of the beta-anomer of [2-13C]N-acetylneuraminic acid was observed upon addition of enzyme, with a concomitant appearance of an anomeric resonance for CMP-N-acetylneuraminic acid. Inhibition by substrate analogues the anomeric oxygen was determined in a similar manner using [2-13C,(50 atom %)18O]N-acetylneuraminic acid. An upfield shift of 1.5 Hz in the anomeric resonance of both the [13C]NeuAc substrate and CMP-[13C]NeuAc product was observed due to the 18O substitution. This result implies conservation of the NeuAc oxygen. Results of steady-state kinetic analysis suggest a sequential-type mechanism and therefore no covalent intermediate. Thus, CMP-beta-NeuAc is probably formed by a direct transfer of the anomeric oxygen of beta-NeuAc to the alpha-phosphate of CTP.

Sequence and expression of the Escherichia coli K1 neuC gene product

The nucleotide sequence of the neuC gene of the Escherichia coli K1 capsule gene cluster encodes a protein with a predicted molecular weight of 44,210 containing 391 amino acids. A chimeric protein with beta-galactosidase fused to the carboxy terminus of the neuC gene product (P7) was constructed and purified. Its amino-terminal sequence confirmed the prediction from the nucleotide sequence that the neuC gene overlaps the distal end of the neuA gene by a single base pair. Both the neuA and neuC genes are coexpressed under the control of a single upstream T7 or tac promoter, suggesting that neuA and neuC are part of an operon.

Prevention of nonspecific binding of immunoglobulin to Staphylococcus aureus protein A in ELISA assays

The Fc region of IgG of most mammals binds protein A on S. aureus resulting in high backgrounds when measuring specific antibodies to S. aureus in the ELISA. Removal of protein A from S. aureus or modification of the Ig Fc to prevent binding to protein A could affect specific antibody binding. We compared effects of blockage of Fc binding to protein A with purified protein A to trypsin removal of protein A from S. aureus, on specific antibody binding. When NMS was incubated without and with protein A (0 microgram, 50 micrograms, 200 micrograms and 400 micrograms) and high protein A Cowan I was the bound S. aureus antigen in the ELISA, absorbance OD405 was 0.769, 0.240, 0.224 and 0.210 +/- SE 0.026. When mouse Mab (IgG1, kappa) to bovine IgA was incubated without and with protein A (400 micrograms) prior to reaction with bovine IgA in the ELISA, absorbance was 0.645 and 0.639, indicating protein A had no effect on specific antibody binding. To determine the effect of trypsin on specific binding, Becker S. aureus was trypsin treated before linking it to microtiter wells. When Mab (IgM) to Becker (Nelles et al., Infect. Immun. (1985) 49, 14) was incubated with protein A (400 micrograms) before use in the ELISA, trypsin treatment of Becker resulted in reduced specific antibody activity (untreated Becker = 1.306, trypsin treated Becker = 0.331). These results suggest that purified protein A can be used to block nonspecific binding via Fc of Ig to S. aureus, thus avoiding trypsin denaturation of surface antigens.

Identity between polysaccharide antigens of Moraxella nonliquefaciens, group B Neisseria meningitidis, and Escherichia coli K1 (non-O acetylated)

A surface polysaccharide antigen of Moraxella nonliquefaciens, reported to be cross-reactive with the capsular polysaccharides of group B Neisseria meningitidis and Escherichia coli K1 (K. Błvre, K. Bryn, O. Closs, N. Hagen, and L. O. Froholm, NIPH Ann. 6:65-73, 1983), was isolated, purified, and characterized chemically, immunologically, and by nuclear magnetic resonance. This polysaccharide was shown to be a linear homopolymer of alpha (2----8)-linked N-acetylneuraminic acid, identical to the capsular polysaccharide of group B N. meningitidis and O-acetyl-negative variants of E. coli K1.

Conscious sedation of pediatric dental patients: an investigation of chloral hydrate, hydroxyzine pamoate, and meperidine vs. chloral hydrate and hydroxyzine pamoate

This study evaluated two oral sedative regimens for the conscious sedation of pediatric dental patients (mean age 37.0 months) unmanageable by traditional behavior management techniques. Regimen A included chloral hydrate (Noctec--E.R. Squibb and Sons, Princeton, NJ) at 50 mg/kg with 25 mg hydroxyzine pamoate (Vistaril--Pfizer Laboratories, New York, NY), plus meperidine (Demerol--Winthrop-Breon, New York, NY) at 1.5 mg/kg. Regimen B included chloral hydrate at 50 mg/kg with 25 mg hydroxyzine pamoate. In a crossover research design, 10 patients were assigned randomly to receive one regimen, to be followed by the alternative regimen during the second appointment. The primary purpose of this study was to determine if meperidine would improve patient behavior, and increase the prevalence of respiratory compromise. A secondary purpose of the study was to develop an objective method to assess behavior during the conscious sedation of pediatric dental patients. Results revealed that the addition of oral meperidine to chloral hydrate and hydroxyzine pamoate resulted in improved behavior (P less than 0.01) during local anesthetic injection, rubber dam delivery, and the operative dental procedure. There was no increase in the prevalence of respiratory compromise with the addition of meperidine.

Synthesis and immunologic properties in mice of vaccines composed of Staphylococcus aureus type 5 and type 8 capsular polysaccharides conjugated to Pseudomonas aeruginosa exotoxin A

Epidemiological, serological and in vitro phagocytosis experiments provide evidence that the newly discovered type 5 and type 8 capsular polysaccharides (CPs) are both virulence factors and protective antigens for bacteremia caused by Staphylococcus aureus. Neither type 5 nor type 8 CP elicited serum antibodies when injected into mice. These two CPs were bound to Pseudomonas aeruginosa exotoxin A (ETA) to form conjugates by using the synthetic scheme devised for the CP (Vi) of Salmonella typhi and of pneumococcus type 12F (A. Fattom, W. F. Vann, S. C. Szu, A. Sutton, X. Li, D. Bryla, G. Schiffman, J. B. Robbins, and R. Schneerson, Infect. Immun. 56:2292-2298, 1988; S. C. Szu, A. L. Stone, J. D. Robbins, R. Schneerson, and J. B. Robbins, J. Exp. Med. 166:1510-1524, 1987). Both S. aureus CP-ETA conjugates elicited a rise in CP antibodies. As components of conjugates, both S. aureus CPs acquired T-cell-dependent properties, as shown by their ability to respond to carrier priming and to stimulate booster responses. The conjugate-induced antibodies facilitated type-specific opsonization of S. aureus by human polymorphonuclear leukocytes. The conjugates also induced ETA antibodies which neutralized the native toxin in vitro. Clinical studies of these two conjugates for active or passive immunization of patients at risk for S. aureus bacteremia are planned.

Structure of the type 5 capsular polysaccharide of Staphylococcus aureus

The Staphylococcus aureus type 5 capsular polysaccharide is composed of 2-acetamido-2-deoxy-L-fucose (1 part), 2-acetamido-2-deoxy-D-fucose (1 part), and 2-acetamido-2-deoxy-D-mannuronic acid (1 part). On the basis of methylation analysis, optical rotation, high-field one- and two-dimensional 1H- and 13C-n.m.r. experiments, and selective cleavage with 70% aqueous hydrogen fluoride, the polysaccharide was found to be a partially O-acetylated (50%) polymer of the repeating trisaccharide unit, [----4)-3-O-Ac-beta-D-ManpNAcA-(1----4)-a-L-FucpNAc-(1----3) -beta-D-FucpNAc-(1----]n.

Serum antibody response in adult volunteers elicited by injection of Streptococcus pneumoniae type 12F polysaccharide alone or conjugated to diphtheria toxoid

Conjugates of an uronic acid-containing capsular polysaccharide (CP), pneumococcous type 12F (Pn12F) bound to diphtheria toxoid (DT), were studied for safety and immunogenicity in adult volunteers. In mice, these conjugates, prepared with the same lot of DT and Pn12F-40234-006, a homogenous CP of high molecular weight, or Pn12-812408, a polydisperse CP with lower-molecular-weight material, were more immunogenic than the Pn12F alone and had T-cell dependent properties (A. Fattom, W. F. Vann, S.C. Szu, A. Sutton, X. Li, B. Bryla, G. Schiffman, J. B. Robbins, and R. Schneerson, Infect. Immun. 56:2292-2298, 1988). Adult volunteers, randomized into three groups, were injected either with one of these two conjugates or with Pnu-Imune, the 23 valent pneumococcus vaccine containing 25 micrograms of Pn12F as one of its components. Volunteers were injected two times, 4 weeks apart, with the Pn12F-DT conjugates and once with the Pnu-Imune. Side reactions following injection of the conjugates of Pnu-Imune were mild and short-lived. At 4 weeks and at 7 months after the first injection, higher levels of Pn12F antibodies were found in the volunteers injected with the conjugates than in the Pnu-Imune group (P less than 0.001). The conjugate prepared with the higher-molecular-weight Pn12F elicited higher levels of antibodies than the conjugate prepared with a lower-molecular-weight Pn12F preparation (P = 0.05). Both conjugates elicited about a 13-fold rise in DT antibodies.