Opportunities in preventive oral health care for children in North Carolina.

Tooth decay affects more children than any other chronic infectious disease, yet it is almost entirely preventable. The Oral Health Section of the North Carolina Division of Public Health stresses the importance of prevention and promotes opportunities for citizens to achieve good oral health as part of total health.

Mice overexpressing human caspase 3 appear phenotypically normal but exhibit increased apoptosis and larger lesion volumes in response to transient focal cerebral ischaemia.

Caspase 3 activation has been implicated in cell death following a number of neurodegenerative insults. To determine whether caspase genes can affect the susceptibility of cells to neurodegeneration, a transgenic mouse line was created, expressing human caspase 3 under control of its own promoter. The human gene was regulated by the murine homeostatic machinery and human procaspase 3 was expressed in the same tissues as mouse caspase 3. These novel transgenic mice appeared phenotypically and developmentally normal and survived in excess of 2 years. Behavioural assessment using the 5-choice serial reaction time task found no differences from wild-type littermates. Caspase activity was found to be tightly regulated under physiological conditions, however, significantly larger lesions were obtained when transgenic mice were subjected to focal cerebral ischaemia/reperfusion injury compared to wild-type littermates. These data demonstrate that mice overexpressing human caspase 3 are essentially normal, however, they have increased susceptibility to degenerative insults.

Phenotyping complex behaviours: assessment of circadian control and 5-choice serial reaction learning in the mouse.

Currently, the behavioural phenotyping of mutant strains is restricted by the paucity of tests for the cognitive capabilities of mice. Most of the paradigms at present available such as the water maze or passive avoidance are dependent upon an aversive component for conditioning and as a consequence the data can often be confounded by the non-specific effects of stress. The development of mutant or transgenic mouse models of human diseases that effect cognitive function will require this confound to be overcome. Here we highlight the value of using two apparently different paradigms, one exploring circadian control and the other visuospatial attention. The first provides an example of an elicited behaviour while the second requires learning; neither is aversive in nature. Interestingly, the data from each strengthens the interpretation of both.

Overexpression of the human VPAC2 receptor in the suprachiasmatic nucleus alters the circadian phenotype of mice.

The neuropeptides vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) belong to a superfamily of structurally related peptide hormones that includes glucagon, glucagon-like peptides, secretin, and growth hormone-releasing hormone. Microinjection of VIP or PACAP into the rodent suprachiasmatic nucleus (SCN) phase shifts the circadian pacemaker and VIP antagonists, and antisense oligodeoxynucleotides have been shown to disrupt circadian function. VIP and PACAP have equal potency as agonists of the VPAC(2) receptor (VPAC(2)R), which is expressed abundantly in the SCN, in a circadian manner. To determine whether manipulating the level of expression of the VPAC(2)R can influence the control of the circadian clock, we have created transgenic mice overexpressing the human VPAC(2)R gene from a yeast artificial chromosome (YAC) construct. The YAC was modified by a strategy using homologous recombination to introduce (i) the HA epitope tag sequence (from influenza virus hemagglutinin) at the carboxyl terminus of the VPAC(2)R protein, (ii) the lacZ reporter gene, and (iii) a conditional centromere, enabling YAC DNA to be amplified in culture in the presence of galactose. High levels of lacZ expression were detected in the SCN, habenula, pancreas, and testis of the transgenic mice, with lower levels in the olfactory bulb and various hypothalamic areas. Transgenic mice resynchronized more quickly than wild-type controls to an advance of 8 h in the light-dark (LD) cycle and exhibited a significantly shorter circadian period in constant darkness (DD). These data suggest that the VPAC(2)R can influence the rhythmicity and photic entrainment of the circadian clock.

Effects of cytisine on hydroxyl radicals in vitro and MPTP-induced dopamine depletion in vivo.

The potential new iron-chelator cytisine and the radical scavenger N-tert-butyl-alpha-(2-sulfophenyl) nitrone (S-PBN) were incubated in a Fenton system and hydroxyl radical formation was measured with the salicylate trapping assay. Both cytisine and S-PBN reduced hydroxyl radical formation in a concentration-dependent manner. For in vivo studies, C57BL/6 mice were injected repeatedly with cytisine (0.5 mg/kg or 2.0 mg/kg s.c.) or saline seven days before and after a single 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) injection (30 mg/kg s.c.). Seven days after MPTP treatment alone dopamine levels were significantly reduced to 12% of the control values (p < 0.001), whereas MPTP + cytisine treatment (2 mg/kg) led to more than twofold higher dopamine levels (p < 0.01) compared with MPTP alone. We have shown for the first time that cytisine attenuates hydroxyl radical formation in vitro and reduces MPTP-induced dopamine depletion. Thus, cytisine may be useful for the treatment of Parkinson's Disease where the chelation of iron ions could prevent neuronal cell death.

Effects of nicotine on hydroxyl free radical formation in vitro and on MPTP-induced neurotoxicity in vivo.

Parkinson's disease (PD) is one of the most frequent disorders of the basal ganglia. From epidemiological studies there is a controversial discussion on the question whether tobacco smoking is correlated with a decreased incidence of PD. The present study aimed to elucidate the role of nicotine and its potential neuroprotective effects in a rodent model of PD. These effects may be related to an altered hydroxyl radical formation; this possibility was studied in vitro. Nicotine and alpha-phenyl-N-tert-butyl nitrone (PBN) were examined in a cell-free in vitro Fenton system (Fe3+/EDTA + H2O2) for their radical scavenging properties using the salicylate trapping method. Salicylic acid (0.5 mM) was incubated in the presence and absence of nicotine or PBN and the main products of the reaction of hydroxyl radicals with salicylic acid, namely 2,3- and 2,5-dihydroxybenzoic acid, were immediately determined using HPLC in combination with electrochemical detection. Nicotine and PBN were both able to significantly reduce hydroxyl radical levels at concentrations of 1, 2.5 and 5 mM. Interestingly, at 5 mM nicotine was able to reduce hydroxyl radical levels significantly more than the radical scavenger PBN (5 mM). To investigate the in vivo effects of nicotine, male C57BL/6 mice were used in the MPTP mouse model of PD. Nicotine (0.1 or 0.4 mg/kg s.c.) was administered twice daily for a period of 14 days. On day 8 a single injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP, 30 mg/kg s.c.) was given as well as an enhanced protocol of nicotine treatment (0.1 or 0.4 mg/kg s.c., 30 min before MPTP and 30, 90, 210, 330, 450, 570 min after MPTP) for a total of seven injections of nicotine. High dosage nicotine treatment significantly increased the MPTP-induced loss of body weight and resulted in a significantly decreased striatal dopamine content and an increased dopamine turnover in comparison with the MPTP-treated controls at day 15. However, the lower dosage of nicotine did not significantly alleviate the MPTP-induced effects, although some parameters showed a slight tendency in this direction. These results demonstrate that in vitro nicotine has radical scavenging properties which might suggest neuroprotective effects. In vivo experiments with nicotine, however, showed that a low dosage of nicotine did not alleviate the MPTP-induced dopamine depletion, but a large dosage even enhanced it.

The prevalence of dental sealants in North Carolina schoolchildren.

OBJECTIVES: This study reports the prevalence of dental sealants derived from a survey of schoolchildren in North Carolina, and its variation according to several sociodemographic characteristics. METHODS: A single-stage, stratified probability sample of grade K-12 classrooms in the state yielded a sample of 8,026 students. Clinical examinations were performed on 83 percent of the sample. Estimates for sealant prevalence and their variation according to seven sociodemographic variables were determined. RESULTS: About 117,000 children in the state, or 12 percent of those 6-17 years of age, have sealants. The prevalence of sealants varied according to geographic region of residence and the socioeconomic status of whites. Prevalence was affected little by age, sex, degree of urbanism, or socioeconomic status of those with races other than white. CONCLUSIONS: While underutilized, there are indications in these data that sealant use is increasing, thus having the potential to contribute to further declines in the prevalence of dental caries in the state. Those factors included in this study and associated with the prevalence of sealants suggest that major gains in sealant use will need to address not only those specific barriers preventing their use by the profession or public, but broader issues preventing the utilization of dental services in general.

Abnormal kinetic behavior of cytochrome oxidase in a case of Leigh disease.

Cultured skin fibroblasts from a child with fatal lacticacidemia displayed an abnormally high lactate:pyruvate ratio of 77:1, compared with control values of 22:1-27:1. When protease-treated isolated mitochondria were used, activity of the respiratory-chain enzymes was found to be approximately 60% of normal, and adenosine triphosphate synthesis was found to be normal with all substrates tested. In mitochondria prepared by means of digitonin treatment, adenosine triphosphate synthesis was depressed with all substrates tested, suggesting a defect in the operation of the cytochrome oxidase complex. In disrupted whole cells from the patient, cytochrome oxidase activity was 56% of the activity in the control cell line with the lowest activity. In the presence of a twofold excess of oxidized cytochrome c, patient cells showed 31% of the activity in controls. Cytochrome oxidase activity in both sonicated whole-cell preparations and in sonicated mitochondria displayed abnormal kinetics with regard to the substrate-reduced cytochrome c, which was particularly evident in the presence of excess oxidized cytochrome c. We believe that kinetically abnormal cytochrome oxidase complex is responsible for the biochemical and clinical abnormalities present in this patient.

Large bimedial rectus recessions in congenital esotropia.

The success rate of large (6 and 7 mm) bimedial rectus recessions in 45 congenital esotropes with deviations of 50 prism dioptres or greater was found to be 91%. Judgment of final alignment was made six weeks postoperatively, with an average follow-up of 13 months. Large bimedial rectus recessions are an effective surgical treatment for congenital esotropia. This procedure does not significantly alter adduction, and leaves other muscles available should further surgery be necessary. These findings show that initial surgery on three or more muscles is unnecessary in congenital esotropia.