The Bone Sialoprotein RGD Domain Modulates and Maintains Periodontal Development.

Bone sialoprotein (gene: Ibsp; protein: BSP) is a multifunctional extracellular matrix protein present in bone, cementum, and dentin. Accumulating evidence supports BSP as a key regulator of mineralized tissue formation via evolutionarily conserved functional domains, including a C-terminal integrin-binding Arg-Gly-Asp (RGD) domain implicated in extracellular matrix-cell signaling. Ablation of Ibsp in mice (Ibsp-/-) results in impaired bone growth and mineralization and defective osteoclastogenesis, with effects in the craniofacial region including reduced acellular cementum formation, detachment of the periodontal ligament (PDL), alveolar bone hypomineralization, and severe periodontal breakdown. We hypothesized that BSP-RGD plays an important role in cementum and alveolar bone formation and mineralization, as well as periodontal function. This hypothesis was tested by replacing the RGD motif with a nonfunctional Lys-Ala-Glu (KAE) sequence in (IbspKAE/KAE) mice and OCCM.30 murine (IbspKAE) cementoblasts. The RGD domain was not critical for acellular or cellular cementum formation in IbspKAE/KAE mice. However, PDL volume and thickness were increased, and significantly more tartrate-resistant acid phosphatase-positive osteoclasts were found on alveolar bone surfaces of IbspKAE/KAE mice versus wild type mice. PDL organization was disrupted as indicated by picrosirius red stain, second harmonic generation imaging, dynamic mechanical analysis, and decreased asporin proteoglycan localization. In vitro studies implicated RGD functions in cell migration, adhesion, and mineralization, and this was confirmed by an ossicle implant model where cells lacking BSP-RGD showed substantial defects as compared with controls. In total, the BSP-RGD domain is implicated in periodontal development, though the scale and scope of changes indicated by in vitro studies indicate that other factors may partially compensate for and reduce the phenotypic severity of mice lacking BSP-RGD in vivo.

A randomised, double-blinded, placebo-controlled study of acupressure wristbands for the prevention of nausea and vomiting during labour and delivery.

INTRODUCTION: Approximately 50% of women experience nausea or vomiting during labour. P6 acupoint stimulation reduces postoperative nausea and vomiting in early pregnancy and after chemotherapy. The aim of this randomised, double-blinded, placebo-controlled trial was to determine whether P6 acupressure prevented nausea and vomiting during labour and delivery. METHODS: After ethical approval and informed consent, women admitted for induction of labour, or in spontaneous labour, were randomised to receive either acupressure bands (Pressure Right) (Group A) or sham placebo bands (Group P) applied to each wrist. Exclusions included recent nausea or vomiting. RESULTS: We consented 365 women and randomised 340 (170 per group). The groups had similar patient and labour characteristics. The incidence of nausea and/or vomiting did not significantly differ (Group A 53% vs. Group P 50%, P=0.58). There was no significant difference between groups (A vs. P, respectively) in the incidence of nausea (52% vs. 45%), vomiting (27% vs. 28%), rescue antiemetic treatment (27% in both), severity of nausea or vomiting, satisfaction with control of nausea or ratings of inconvenience or discomfort from the bands (10% vs. 11%). Factors significantly associated with emetic symptoms were smoking (OR 2.16, 95% CI 1.07-4.37), opioid analgesia (OR 1.95, 95% CI 1.06-3.59), history of motion-induced or postoperative nausea and vomiting (OR 1.85, 95% CI 1.17-2.94) and higher body mass index (OR 1.07, 95% CI 1.01-1.12). CONCLUSION: In this study acupressure wristbands applied bilaterally did not reduce the incidence of nausea and vomiting during labour and delivery.

Airway obstruction with cricoid pressure and lateral tilt.

We studied the effect of cricoid pressure and lateral tilt on airway patency during ventilation by facemask in a simulated obstetric setting. The lungs of 50 patients were ventilated by facemask and Guedel airway using a Nuffield Penlon 200 ventilator and Bain system with standard settings. Expired tidal volumes and peak inspiratory pressures were recorded for 10 breaths in each of four combinations: supine with no cricoid pressure, supine with cricoid pressure, 15 degrees lateral tilt with no cricoid pressure and 15 degrees lateral tilt with cricoid pressure. The timing of cricoid pressure was randomised and blinded to all observers. In both supine and tilted positions, cricoid pressure produced a reduction in tidal volume (p < 0.001) and an increase in peak inspiratory pressure (p < 0.001). Cricoid pressure with lateral tilt did not produce any additional airway obstruction to that in the supine position. Complete airway obstruction (tidal volume < 200 ml) resulted on three occasions, all with cricoid pressure applied.