The effect of green tea as an adjunct to scaling and root planing in non-surgical periodontitis therapy: a systematic review

OBJECTIVE To provide a systematic overview on the efficacy of green tea catechin as an adjunct to scaling and root planing (SRP) in terms of probing pocket depth (PPD). MATERIALS AND METHODS A systematic literature search was performed using electronic databases in PubMed, Scopus, Medline, Cochrane, CINAHL, and Web of Science on randomized clinical trials up to January 2017. The research question was posed in accordance with PRISMA guidelines. RESULTS The search provided 234 studies. After analyzing the full texts, five studies were included, with four studies qualifying for meta-analysis. Mean PPD reduction was significantly higher (α = 0.05) when green tea catechin was used as an adjunct to SRP (test group) than with SRP alone (control group). The difference in the reduction was 0.74 mm [0.35-1.13; 95% CI]. CONCLUSION The local application of green tea catechin as an adjunct to SRP may result in a beneficial reduction in PPD. Due to the highly heterogeneous data and some risk of bias, however, this data still needs to be interpreted with caution. CLINICAL RELEVANCE The finding suggests that green tea catechin may be a topical adjunct to SRP without negative side effects

Examining molecular interactions and dynamics in centrosome and centriole assembly

Centrioles are cellular organelles that give rise to the centrosome, a structure composed of a pair of centrioles surrounded by pericentriolar material. Centrosomes perform a variety of different cellular functions: they are the main microtubule organising centre in animal cells and are important signalling hubs. The centrosome is composed of hundreds of different proteins, but only a handful are essential. In Drosophila, Sak/Plk4, Ana2, Sas-6, Sas-4 and Asl are required for centriole assembly and Spd-2 and Cnn are indispensable for PCM assembly. Many questions remain regarding how these proteins behave, interact and are regulated, as genetic analysis of these processes is often complicated by the absence of centrioles when these proteins are mutated. In this thesis, I apply recent technological advancements and a biological model system to the study of essential centriole proteins. Using newly developed fluorescent proteins, I am able to localise Sak over the cell cycle in live embryos. Developing and applying a correlative microscopy approach, I was able to localise the protein termini of Ana2 and Sas-6 with nanometre precision to the centriole cartwheel. With the further characterisation and utilization of an in vivo centriole model system, I shed light on the direct contribution of Sak, Asl and Sas-4 on the Ana2/Sas-6 interaction, definitively identify the role of Asl in Spd-2 and Cnn recruitment, and develop a protein-protein interaction assay. The latter led me to identify novel Cdk1/Cyclin B phosphorylation sites on Ana2, providing a possible insight into the cell cycle and centriole duplication cycle link.</p

The Effect of Green Tea on plaque and gingival inflammation: A systematic review

Green tea has been shown in individual studies to be effective in reducing plaque and its use against gingivitis. Therefore, the aim of this study was to systematically review available literature on green tea catechin. The systematic literature search was performed using electronic databases in CINAHL, Cochrane Library, MEDLINE, PubMed and Scopus until January 2017. The PRISMA criteria were applied and a research question was posed according to PICO: “In patients with gingivitis (population), what is the effect of green tea catechins-containing mouthwash (intervention and comparison) on plaque accumulation and gingival inflammation (outcome)?”. Out of 187 titles identified by the search strategy, five were suitable for meta-analyses. These five studies were undertaken on a predominately Asian population. Plaque (PI) and Gingival Index (GI) were compared at endpoint and with respect to the change throughout the study (baseline-endpoint). The results from the meta-analysis indicated that green tea and chlorhexidine (CHX) resulted in lower PI compared to placebo while there was no significant difference between CHX and green tea, either at endpoint or over time. In addition, there was little evidence of side effects with green tea mouthwash. Green tea mouthwash may be a viable alternative to CHX, especially for long-term use. However, due to the very heterogeneous data and the risk of bias, this evidence should be interpreted with caution. Further clinically controlled studies with a longer observation period are required

Cdk1 phosphorylates Drosophila Sas-4 to recruit Polo to daughter centrioles and convert them to centrosomes

Centrosomes and cilia are organized by a centriole pa ir comprising an older mother and a younger daughter. Centriole numbers are tightly regulated and daughter centrioles (that assemble in S-phase) cannot themselves duplicate or organise centrosomes until they have passed through mitosis. It is unclear how this mitotic “centriole conversion” is regulated, but it requires Plk1/Polo kinase. Here we show that in flies Cdk1 phosphorylates the conserved centriole protein Sas- 4 during mitosis. This creates a Polo-docking site that helps recruit Polo to daughter centrioles, and is required for the subsequent recruitment of Asterless (Asl) — a protein essential for centriole duplication and mitotic centrosome assembly. Point mutations in Sas-4 th at prevent Cdk1 phosphorylation or Polo - docking do not block centriole disengagement during mitosis , but block efficient centriole conversion and lead to embryonic lethality. These observations can explain why daughter centrioles have to pass through mitosis before they can duplicate and organise a centrosome.</p

A combined 3D-SIM/SMLM approach allows centriole proteins to be localised with a precision of ~4-5nm

Centrioles are small barrel-shaped structures that form centrosomes and cilia [1]. Centrioles assemble around a central cartwheel comprising the Sas-6 and Ana2/STIL proteins. The amino termini of nine Sas-6 dimers form a central hub of ∼12 nm radius from which nine dimer spokes radiate, placing the Sas-6 carboxyl termini at the outer edge of the ∼60 nm radius cartwheel [2]. Several centriole proteins are distributed in a toroid around the cartwheel, and super-resolution light microscopy studies have measured the average radii of these ∼100–200 nm radius toroids with a ‘precision’ — or standard deviation (s.d. or 1σ) — of ±∼10–40 nm. The organization of Ana2/STIL within the cartwheel, however, has not been resolvable. Here, we develop methods to calculate the average toroidal radius of centriolar proteins in the ∼20–60 nm range with a s.d. of just ±∼4–5 nm, revealing that the amino and carboxyl termini of Ana2 are located in the outer cartwheel region

Drosophila Sas-6, Ana2 and Sas-4 self-organise into macromolecular structures that can be used to probe centriole and centrosome assembly

Centriole assembly requires a small number of conserved proteins. The precise pathway of centriole assembly has been difficult to study, as the lack of any one of the core assembly proteins [Plk4, Ana2 (the homologue of mammalian STIL), Sas-6, Sas-4 (mammalian CPAP) or Asl (mammalian Cep152)] leads to the absence of centrioles. Here, we use Sas-6 and Ana2 particles (SAPs) as a new model to probe the pathway of centriole and centrosome assembly. SAPs form in Drosophila eggs or embryos when Sas-6 and Ana2 are overexpressed. SAP assembly requires Sas-4, but not Plk4, whereas Asl helps to initiate SAP assembly but is not required for SAP growth. Although not centrioles, SAPs recruit and organise many centriole and centrosome components, nucleate microtubules, organise actin structures and compete with endogenous centrosomes to form mitotic spindle poles. SAPs require Asl to efficiently recruit pericentriolar material (PCM), but Spd-2 (the homologue of mammalian Cep192) can promote some PCM assembly independently of Asl. These observations provide new insights into the pathways of centriole and centrosome assembly

An autonomous oscillator times and executes centriole biogenesis

The accurate timing and execution of organelle biogenesis is crucial for cell physiology. Centriole biogenesis is regulated by Polo-like kinase 4 (Plk4) and initiates in S-phase when a daughter centriole grows from the side of a preexisting mother. Here we show that Plk4 forms an adaptive oscillator at the base of the growing centriole to initiate and time centriole biogenesis, ensuring that centrioles grow at the right time and to the right size. The Plk4 oscillator is normally entrained to the cell-cycle oscillator, but can run autonomously of it – explaining how centrioles can duplicate independently of cell cycle progression under certain conditions. Mathematical modelling indicates that this autonomously oscillating system is generated by a time-delayed negative-feedback loop in which Plk4 inactivates its centriolar receptor through multiple rounds of phosphorylation. We postulate that such organelle-specific autonomous oscillators could regulate the timing and execution of organelle biogenesis more generally

An autonomous oscillator times and executes centriole biogenesis

The accurate timing and execution of organelle biogenesis is crucial for cell physiology. Centriole biogenesis is regulated by Polo-like kinase 4 (Plk4) and initiates in S-phase when a daughter centriole grows from the side of a preexisting mother. Here we show that Plk4 forms an adaptive oscillator at the base of the growing centriole to initiate and time centriole biogenesis, ensuring that centrioles grow at the right time and to the right size. The Plk4 oscillator is normally entrained to the cell-cycle oscillator, but can run autonomously of it – explaining how centrioles can duplicate independently of cell cycle progression under certain conditions. Mathematical modelling indicates that this autonomously oscillating system is generated by a time-delayed negative-feedback loop in which Plk4 inactivates its centriolar receptor through multiple rounds of phosphorylation. We postulate that such organelle-specific autonomous oscillators could regulate the timing and execution of organelle biogenesis more generally

An autonomous oscillation times and executes centriole biogenesis

The accurate timing and execution of organelle biogenesis is crucial for cell physiology. Centriole biogenesis is regulated by Polo-like kinase 4 (Plk4) and initiates in S-phase when a daughter centriole grows from the side of a pre-existing mother. Here, we show that a Plk4 oscillation at the base of the growing centriole initiates and times centriole biogenesis to ensure that centrioles grow at the right time and to the right size. The Plk4 oscillation is normally entrained to the cell-cycle oscillator but can run autonomously of it—potentially explaining why centrioles can duplicate independently of cell-cycle progression. Mathematical modeling indicates that the Plk4 oscillation can be generated by a time-delayed negative feedback loop in which Plk4 inactivates the interaction with its centriolar receptor through multiple rounds of phosphorylation. We hypothesize that similar organelle-specific oscillations could regulate the timing and execution of organelle biogenesis more generally