Hydroxyapatite in Oral Care Products—A Review

Calcium phosphate compounds form the inorganic phases of our mineralised tissues such as bone and teeth, playing an important role in hard tissue engineering and regenerative medicine. In dentistry and oral care products, hydroxyapatite (HA) is a stable and biocompatible calcium phosphate with low solubility being used for various applications such as tooth remineralisation, reduction of tooth sensitivity, oral biofilm control, and tooth whitening. Clinical data on these products is limited with varied results; additionally, the effectiveness of these apatite compounds versus fluoride, which has conventionally been used in toothpaste, has not been established. Therefore, this review critically evaluates current research on HA oral care, and discusses the role and mechanism of HA in remineralisation of both enamel and dentine and for suppressing dentine sensitivity. Furthermore, we position HA’s role in biofilm management and highlight the role of HA in dental applications by summarising the recent achievement and providing an overview of commercialised HA dental products. The review also indicates the existing limitations and provides direction for future research and commercialisation of apatite-based oral care products.     

Chlorinated englerins with selective inhibition of renal cancer cell growth

The chlorinated englerins (3-9) were isolated from Phyllanthus engleri and shown to selectively inhibit the growth of renal cancer cells. The compounds were shown to be extraction artifacts produced by exposure to chloroform decomposition products during their isolation. The most active compound, 3, was synthesized from englerin A (1).     

Oral health promotion interventions on oral yeast in hospitalised and medically compromised patients: a systematic review

Yeast are major aetiological agents of localised oral mucosal lesions, and are also leading causes of nosocomial bloodstream infections. The purpose of this systematic review was to examine the effectiveness of oral health promotion interventions on the prevalence and incidence of these opportunistic oral pathogens in hospitalised and medically compromised patients. The PubMed, ISI Web of Science and Cochrane Library databases were searched for clinical trials assessing the effect of oral health promotion interventions on oral yeast. Chlorhexidine delivered in a variety of oral hygiene products appeared to have some effect on oral yeast, although some studies found equivocal effects. Although a wide array of other compounds have also been investigated, their clinical effectiveness remains to be substantiated. Likewise, the utility of mechanical oral hygiene interventions and other oral health promotion measures such as topical application of salivary substitute, remains unsettled. Although many chemical agents contained in oral hygiene products have proven in vitro activity against oral yeast, their clinical effectiveness and potential role as adjuncts or alternative therapies to conventional treatment remains to be confirmed by further high-quality randomised controlled trials. This is pertinent, given the recent emergence of yeast resistance to conventional antifungal agents.     

Saliva promotes Candida albicans adherence to human epithelial cells

Adhesion of Candida cells to oral surfaces is an initial event in pathogenesis. Since specific immobilized salivary components mediate the binding of Candida albicans to hydroxyapatite, we hypothesized that saliva may also promote adherence to oral epithelia via a similar mechanism. In an in vitro model, C. albicans ATCC 10261 yeast cells adhered in a saturable manner to monolayers of three cultured human epithelial cell lines (A549, HEp-2, and HET-1A). The addition of whole saliva to the assay promoted the binding of C. albicans to all cell lines in a dose-dependent manner, but pre-incubation of the epithelial cells with pooled whole saliva had no effect on subsequent adherence. Pre-incubation of the yeast cells with pooled whole saliva, however, significantly enhanced (by up to 120%, P < 0.05) binding to epithelial cell monolayers, and pooled saliva that had been pre-incubated with C. albicans yeast cells was defective in promoting yeast adherence. There was a negative correlation (r = 0.68, P < 0.005) between specific IgA titers against whole cells of C. albicans and adherence-promoting activities for individual saliva samples. The adhesion-inhibitory effect of specific anti-C. albicans IgA was reversed by depletion of IgA from saliva by affinity chromatography. Factors in whole saliva, therefore, bound to the yeast cells, counter the C. albicans-specific salivary IgA inhibitory effect on adhesion and promote the adherence of C. albicans yeast cells to cultured epithelial cells.     

Toxoplasma, Toxocara and Tuberculosis co-infection in a four year old child

Background

Tuberculosis. toxocariasis and toxoplasmosis are among the common infectious causes of lymphadenitis in children. Cases of Toxoplasma gondii and Toxocara spp co-infection have been reported.

Case Presentation

This case report describes a co-infection of Toxoplasma gondii, Toxocara spp and tuberculosis in a child with chronic lymphadenopathy and eosinophilia.

Conclusion

The case report highlights two important points. First is the diagnostic challenges that are encountered by clinicians in tropical countries such as Sri Lanka, where lymphadenopathy and eosinophilia with a positive serology commonly point towards a parasitic infection. Secondly the importance of proper history taking and performing the Mantoux test as a first line investigation in a country where the incidence of tuberculosis is low, even in the absence of a positive contact history.     

Effects of supplemental cystine or methionine on growth and lifespan of stroke-prone spontaneously hypertensive rats

Stroke-prone spontaneously hypertensive (SHRSP) rats are considered a suitable model for studying the effects of dietary and other environmental factors on human essential hypertension and haemorrhagic stroke. To investigate the suitability of a control diet for this strain of rats, we studied the effects of supplementing casein and soya protein isolate (SPI) with two sulphur amino acids (methionine and cystine) on the growth and lifespan of SHRSP rats. The source of dietary protein and the type of supplemental sulphur amino acid had significant (P < 0.05) effects on food intake and weight gain measured after 31 d of the feeding study, while only the type of supplemental sulphur amino acid had significant effects on mean survival times and the survival rates. On average, the casein groups had higher food intake and weight gain compared with the SPI groups. The methionine-supplemented groups had lower food intake but higher weight gain than the cystine-supplemented groups. Similarly, the methionine-supplemented groups had higher mean survival times and survival rates compared with the cystine-supplemented groups. The data would suggest that a control diet based on cystine-supplemented casein (as recommended for normal healthy rats by the American Institute of Nutrition), may not meet the sulphur amino acid requirements for SHRSP rats, and that the methionine-supplemented casein would be an appropriate control diet for this animal model.