Effect of casein phosphopeptide-amorphous calcium phosphate added to acidic beverages on enamel erosion in vitro

BACKGROUND

To investigate, in vitro, the effect on enamel erosion of the addition of 0.2% w/v casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) to four commercially-available soft drinks, two of which were carbonated.

METHODS

Enamel specimens (n=27) were sectioned from sound extracted human third molar teeth and polished to a mirror finish. Exposed enamel windows of 1 mm2 were created by painting the surface with acid-resistant nail varnish. Four citric flavoured soft drinks (pH range 2.2 to 2.4) and distilled deionized water (DDW) were tested. Each drink was tested with and without 0.2% CPP-ACP w/v. The specimens were placed into 50 mL of solution at 37 °C for 30 minutes, rinsed and varnish removed. The samples were profiled with a white light profilometer and erosive depths recorded.

RESULTS

All soft drinks tested caused enamel erosion but adding 0.2% w/v CPP-ACP significantly reduced (p<.05) erosive depth in all test solutions in comparison with the solutions without CPP-ACP. The erosive depths for all solutions with 0.2% CPP-ACP did not differ significantly from those of DDW.

CONCLUSIONS

Adding CPP-ACP at 0.2% w/v significantly decreased the erosivity of all four soft drinks. The erosivity of the soft drinks with 0.2% CPP-ACP added did not differ significantly from that of distilled water.

New Approaches to Enhanced Remineralization of Tooth Enamel

Dental caries is a highly prevalent diet-related disease and is a major public health problem. A goal of modern dentistry is to manage non-cavitated caries lesions non-invasively through remineralization in an attempt to prevent disease progression and improve aesthetics, strength, and function. Remineralization is defined as the process whereby calcium and phosphate ions are supplied from a source external to the tooth to promote ion deposition into crystal voids in demineralized enamel, to produce net mineral gain. Recently, a range of novel calcium-phosphate-based remineralization delivery systems has been developed for clinical application. These delivery systems include crystalline, unstabilized amorphous, or stabilized amorphous formulations of calcium phosphate. These systems are reviewed, and the technology with the most scientific evidence to support its clinical use is the remineralizing system utilizing casein phosphopeptides to stabilize and deliver bioavailable calcium, phosphate, and fluoride ions. The recent clinical evidence for this technology is presented and the mechanism of action discussed. Biomimetic approaches to stabilization of bioavailable calcium, phosphate, and fluoride ions and the localization of these ions to non-cavitated caries lesions for controlled remineralization show promise for the non-invasive management of dental caries.

Effect of synthetic cannabinoid HU210 on memory deficits and neuropathology in Alzheimer's disease mouse model

Cannabinoids have been shown to increase neurogenesis in adult brain, as well as protect neurons from excitotoxicity, calcium influx, inflammation, and ischemia. Recent studies have shown that synthetic cannabinoids can alleviate water maze impairments in rats treated with intracranial amyloid beta protein (Abeta); however it is unknown whether this effect is due to the cannabinoids' anti-inflammatory properties or whether it affects Abeta processing. Here we investigate whether cannabinoids have any effect on Alzheimer's disease in vivo. We found that HU210, a potent synthetic cannabinoid, did not improve water maze performance or a contextual fear conditioning task in an APP23/PS45 double transgenic mouse model of AD. HU210 had no effect on APP processing and Abeta generation, as well as neuritic plaque formation in the brains of AD transgenic mice. Our study showed that synthetic cannabinoid HU210 had no beneficial effects on AD neuropathology and behavioral deficits of AD model mice, which advises caution of such drug's application in AD therapies.

Protein degradation by the proteasome is required for synaptic tagging and the heterosynaptic stabilization of hippocampal late-phase long-term potentiation

Activity-dependent regulation of synaptic efficacy is believed to underlie learning and memory formation. Here we show that protein degradation by the proteasome is required for the induction of the protein synthesis-dependent late-phase of long-term potentiation (late-LTP) but not for its maintenance. Proteasome activity was also key to the polarity of heterosynaptic interactions between synapses expressing synaptic plasticity and newly activated synapses. In fact, proteasome activity was required for the consolidation of an otherwise transient potentiation (early-LTP) into late-LTP by strong tetanization of a separate afferent pathway both in the "weak-before-strong" and in the "strong-before-weak" two-pathway paradigms [Frey and Morris (1997) Nature 385:533-536; Frey and Morris (1998) Neuropharmacology 37:545-552], suggesting that proteasome activity plays a role in the synaptic tagging and capture of plasticity-related proteins at stimulated synapses. Additionally, proteasome inhibition abrogated immunity against heterosynaptic depotentiation of an established late-LTP when applied during weak tetanic stimulation in the "strong-before-weak" two-pathway paradigm. Such a heterosynaptic destabilizing effect of proteasome inhibition was abolished by concomitant inhibition of N-methyl-d-aspartate (NMDA) receptors, suggesting that it is an active process. Together, these results indicate that the proteasome plays important roles in the establishment of late-LTP and in the preservation of potentiated synapses when a subsequent synaptic plasticity is induced within the same neuronal population.

Prokaryotic expression of a novel mouse pro-apoptosis protein PNAS-4 and application of its polyclonal antibodies

Mouse PNAS-4 (mPNAS-4) has 96% identity with human PNAS-4 (hPNAS-4) in primary sequence and has been reported to be involved in the apoptotic response to DNA damage. However, there have been no studies reported of the biological functions of mPNAS-4. In studies conducted by our group (unpublished data), it was interesting to note that overexpression of mPNAS-4 promoted apoptotic death in Lewis lung carcinoma cells (LL2) and colon carcinoma cells (CT26) of mice both in vitro and in vivo. In our studies, mPNAS-4 was cloned into the pGEX-6P-1 vector with GST tag at N-terminal in Escherichia coli strain BL21(DE3). The soluble and insoluble expression of recombinant protein mPNAS-4 (rmPNAS-4) was temperature-dependent. The majority of rmPNAS-4 was insoluble at 37 degrees C, while it was almost exclusively expressed in soluble form at 20 degrees C. The soluble rmPNAS-4 was purified by one-step affinity purification, using a glutathione Sepharose 4B column. The rmPNAS-4 protein was further identified by electrospray ionization-mass spectrometry analysis. The search parameters of the parent and fragment mass error tolerance were set at 0.1 and 0.05 kDa, respectively, and the sequence coverage of search result was 28%. The purified rmPNAS-4 was further used as immunogen to raise polyclonal antibodies in New Zealand white rabbit, which were suitable to detect both the recombinant and the endogenous mPNAS-4 in mouse brain tissue and LL2 cells after immunoblotting and/or immunostaining. The purified rmPNAS-4 and our prepared anti-mPNAS-4 polyclonal antibodies may provide useful tools for future biological function studies for mPNAS.

Hypothalamic preproghrelin gene expression is repressed by insulin via both PI3-K/Akt and ERK1/2 MAPK pathways in immortalized, hypothalamic neurons

The gut peptide ghrelin is expressed within neurons of the hypothalamus. Using a hypothalamic cell line, mHypoE-38 neurons, the effect of insulin on preproghrelin gene expression was assayed. These cells contain neuron-specific markers, preproghrelin and the insulin receptor. We determined that insulin has direct effects on preproghrelin gene expression. Insulin (10 nM) stimulated protein kinase B (Akt) and extracellular signal-regulated kinase 1 and 2 (ERK1/2) phosphorylation from 5 to 60 min and 5 min, respectively, and led to repression of preproghrelin gene expression at 2 h. Pharmacological inhibitors to phosphoinositide-3-kinase (PI3-K; LY294002) and MEK (PD98059) demonstrated that basal ghrelin gene expression is regulated by the PI3-K pathway and requires the mitogen-activated protein kinase pathway for insulin-stimulated preproghrelin repression. These results demonstrate that insulin has a direct effect on hypothalamic neurons to decrease preproghrelin gene expression through classic insulin pathways.

Fluoride and casein phosphopeptide-amorphous calcium phosphate

Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) slows the progression of caries and remineralizes enamel subsurface lesions. The aim of this study was to determine the ability of CPP-ACP to increase the incorporation of fluoride into plaque and to promote enamel remineralization in situ. Randomized, double-blind, cross-over studies involved mouthrinses and dentifrices containing CPP-ACP and fluoride. The mouthrinses were used for 60 sec, three times/day for 5 days, and supragingival plaque was collected and analyzed for F. The dentifrices were rinsed as a water slurry for 60 sec four times/day for 14 days in an in situ model. The addition of 2% CPP-ACP to the 450-ppm-F mouthrinse significantly increased the incorporation of fluoride into plaque. The dentifrice containing 2% CPP-ACP produced a level of remineralization similar to that achieved with a dentifrice containing 2800 ppm F. The dentifrice containing 2% CPP-ACP plus 1100 ppm F was superior to all other formulations.

Remineralization of enamel subsurface lesions in situ by sugar-free lozenges containing casein phosphopeptideamorphous calcium phosphate

BACKGROUND

The anticariogenic potential of casein phosphopeptide-amorphous calcium phosphate nanocomplexes (CPP-ACP) has been demonstrated using laboratory, animal and human in situ caries models. The aim of this study was to determine the effect of CPP-ACP incorporation into a sugar-free lozenge (pressed mint tablet) on enamel remineralization in a human in situ model.

METHODS

The study utilized a double-blind, randomized, cross-over design with four treatments: (i) a lozenge containing 56.4mg (3 per cent w/w) CPP-ACP; (ii) a lozenge containing 18.8mg (1 per cent w/w) CPP-ACP; (iii) a lozenge not containing CPP-ACP; and (iv) a no lozenge nil-treatment control. Ten subjects wore removable palatal appliances with four, human-enamel, half-slab insets containing subsurface lesions. Lozenges were consumed, without chewing, four times per day for 14 days duration. After each treatment period the enamel slabs were removed, paired with their respective demineralized control, embedded, sectioned and subjected to microradiography and computer-assisted densitometric image analysis to determine the level of remineralization.

RESULTS

The incorporation of CPP-ACP into the lozenge significantly increased enamel subsurface lesion remineralization with 18.8 and 56.4mg of CPP-ACP increasing remineralization by 78 and 176 per cent respectively, relative to the control sugarfree lozenge.

CONCLUSION

This study demonstrates that lozenges are a suitable vehicle for the delivery of CPP-ACP to promote enamel remineralization.

Effect of addition of citric acid and casein phosphopeptide-amorphous calcium phosphate to a sugar-free chewing gum on enamel remineralization in situ

Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) has been shown to remineralize enamel subsurface lesions in situ. The aim of this study was to investigate the effects of CPP-ACP in a fruit-flavoured sugar-free chewing gum containing citric acid on enamel remineralization, and acid resistance of the remineralized enamel, using an in situ remineralization model. The study utilized a double-blind, randomized, crossover design with three treatments: (i) sugar-free gum (2 pellets) containing 20 mg citric acid and 18.8 mg CPP-ACP, (ii) sugar-free gum containing 20 mg citric acid alone, (iii) sugar-free gum not containing CPP-ACP or citric acid. Ten subjects were instructed to wear removable palatal appliances, with 4 half-slab insets of human enamel containing demineralized subsurface lesions and to chew gum (2 pellets) for 20 min 4 times per day for 14 days. At the completion of each treatment the enamel half-slabs were removed and half of the remineralized lesion treated with demineralization buffer for 16 h in vitro. The enamel slabs (remineralized, acid-challenged and control) were then embedded, sectioned and subjected to microradiography to determine the level of remineralization. Chewing with gum containing citric acid and CPP-ACP resulted in significantly higher remineralization (13.0 +/- 2.2%) than chewing with either gum containing no CPP-ACP or citric acid (9.4 +/- 1.2%) or gum containing citric acid alone (2.6 +/- 1.3%). The acid challenge of the remineralized lesions showed that the level of mineral after acid challenge was significantly greater for the lesions exposed to the gum containing CPP-ACP.

Modulation of the oxidative stress and nuclear factor kappaB activation by theaflavin 3,3'-gallate in the rats exposed to cerebral ischemia-reperfusion

The major pathobiological mechanisms of IR injury include excitotoxicity, oxidative stress, and inflammation. TF3, a major constituent of black tea, possesses biological functions such as anti-oxidative and anti-inflammatory activities. The purpose of this study was to verify the neuronal protective potential of TF3 and its mechanisms against cerebral IR injury in rats. TF3 administration (10 and 20 mg.kg-1) ameliorated the infarct volume. TF3 also decreased the content of MDA and NO. TF3 significantly increased the activity of SOD and GSH-Px, which were reduced by IR injury. Administration of TF3 decreased mRNA and protein expression of COX-2 and iNOS. DNA binding and Western blotting revealed an increase in NF-kappaB activation and IkappaB depletion in IR brain tissue. Pretreatment with TF3 markedly inhibited IRinduced increase in nuclear localization of NF-kappaB, and preserved IkappaB in the cytoplasm. The results show that TF3 exerts protective effects against cerebral IR injury by reducing oxidative stress and modulating the NF-kappaB activation.

An improved mechanical technique for assisted hatching

BACKGROUND

Varied clinical outcomes of assisted hatching (AH) have been reported. We attempt to investigate whether the size of the zona opening created by AH is adequate for blastocyst hatching, and, if not, set up a new method to improve it.

METHODS

A new AH technique, long zona dissection (LZD), was established, and experiments were performed to compare the effects of different sizes of zona opening on complete hatching of blastocysts in mouse and human embryos in vitro.

RESULTS

The LZD technique can create a long zona slit on early embryos, even blastocysts, with the slit size beyond two-thirds of zona diameter. Compared with three-dimensional partial zona dissection, LZD can significantly enhance the hatching speed and the rate of complete hatching of mouse blastocysts (93.9%). All (100%) human blastocysts completely hatched following LZD; however, when the slit size after AH was about two-fifths of zona diameter, more of the larger inner cell masses (ICM) became trapped by the zona opening during hatching than the smaller ICM (53.3 versus 12.5%, P = 0.01).

CONCLUSIONS

Zona opening of moderate size following AH is inadequate for the completion of blastocyst hatching in vitro; in some cases, however, it can be significantly improved by LZD.

Acid resistance of enamel subsurface lesions remineralized by a sugar-free chewing gum containing casein phosphopeptide-amorphous calcium phosphate

The aim of this clinical study was to investigate the acid resistance of enamel lesions remineralized in situ by a sugar-free chewing gum containing casein phosphopeptide-amorphous calcium phosphate nanocomplexes (CPP-ACP: Recaldent). The study utilized a double-blind, randomized, crossover design with two treatments: (i) sugar-free gum containing 18.8 mg of CPP-ACP, and (ii) sugar-free gum not containing CPP-ACP as control. Subjects wore removable palatal appliances with insets of human enamel containing demineralized subsurface lesions and chewed the gum for 20 min 4 times per day for 14 days. After each treatment the enamel slabs were removed and half of each lesion challenged with acid in vitro for 8 or 16 h. The level of remineralization was determined using microradiography. The gum containing CPP-ACP produced approximately twice the level of remineralization as the control sugar-free gum. The 8- and 16-hour acid challenge of the lesions remineralized with the control gum resulted in 65.4 and 88.0% reductions, respectively, of deposited mineral, while for the CPP-ACP-remineralized lesions the corresponding reductions were 30.5 and 41.8%. The acid challenge after in situ remineralization for both control and CPP-ACP-treated lesions resulted in demineralization underneath the remineralized zone, indicating that the remineralized mineral was more resistant to subsequent acid challenge. The results show that sugar-free gum containing CPP-ACP is superior to an equivalent gum not containing CPP-ACP in remineralization of enamel subsurface lesions in situ with mineral that is more resistant to subsequent acid challenge.

Confirmation and refinement of a genetic locus for disseminated superficial actinic porokeratosis (DSAP1) at 12q23.2-24.1

BACKGROUND

Our previous study has identified two loci for disseminated superficial actinic porokeratosis (DSAP), but the genes responsible are still unknown.

OBJECTIVES

To narrow down the candidate regions and to assess candidate genes.

METHODS

A genome-wide scan and linkage analysis were carried out in a newly collected five-generation Chinese family with DSAP. In addition, six candidate genes were screened for possible DSAP-associated mutations.

RESULTS

DSAP in this family was associated with chromosome 12q. Fine mapping and haplotype construction refined the DSAP1 locus to a 4.4-cM interval. No disease-associated mutation was detected in CRY1, C4ST1, TXNRD1, HCF2, CMKLR1 or KIAA0789 genes.

CONCLUSIONS

The DSAP1 locus was localized to a 4.4-cM interval at chromosome 12q23.2-24.1. CRY1, C4ST1, TXNRD1, HCF2, CMKLR1 and KIAA0789 genes were not associated with DSAP1.