High-throughput measurement of single-cell growth rates using serial microfluidic mass sensor arrays.

Methods to rapidly assess cell growth would be useful for many applications, including drug susceptibility testing, but current technologies have limited sensitivity or throughput. Here we present an approach to precisely and rapidly measure growth rates of many individual cells simultaneously. We flow cells in suspension through a microfluidic channel with 10-12 resonant mass sensors distributed along its length, weighing each cell repeatedly over the 4-20 min it spends in the channel. Because multiple cells traverse the channel at the same time, we obtain growth rates for >60 cells/h with a resolution of 0.2 pg/h for mammalian cells and 0.02 pg/h for bacteria. We measure the growth of single lymphocytic cells, mouse and human T cells, primary human leukemia cells, yeast, Escherichia coli and Enterococcus faecalis. Our system reveals subpopulations of cells with divergent growth kinetics and enables assessment of cellular responses to antibiotics and antimicrobial peptides within minutes.

Expression status of mRNA for sex hormone receptors in human dental pulp cells and the response to sex hormones in the cells.

OBJECTIVES: Sex hormone receptors are reported to be present in human dental pulp (HDP) cells. The purpose of this study was to examine the biological significance of oestrogen and androgen receptors (ER and AR, respectively) in HDP cells. DESIGN: We isolated HDP cells expressing ER- and AR-mRNAs and investigated the expression status of the receptors and the response to sex hormones in the cells. RESULTS: HDP cells expressing ER- and/or AR-mRNAs had the ability to form alizarin red S-positive nodules in which calcium and phosphorus were deposited in vitro and to differentiate into odontoblasts-like cells and dentine-like tissue in vivo. Individual clones isolated from HDP cells exhibited a different expression pattern of mRNA for ER and AR. Some clones expressed ERα- and/or ERß-mRNAs and the others coexpressed ER- and AR-mRNAs. Using the Ingenuity software, we found that 17ß-estradiol (E2) and dihydrotestosterone (DHT) could act directly on HDP cells through ER-or androgen signalling-mediated mechanisms. E2 or DHT stimulated the mRNA expression for genes related to odontogenesis of dentine-containing teeth and odontoblast differentiation, suggesting that ER and AR in HDP cells may be involved in dentinogenesis. CONCLUSIONS: Our findings provide new insights into the biological significance of sex hormone receptors in HDP cells.

Observation of calcium phosphate powder mixed with an adhesive monomer experimentally developed for direct pulp capping and as a bonding agent.

In this study, morphological shape, elemental distribution and elution properties of Ca, P, Mg in four types of calcium phosphate powder were investigated using SEM, EPMA and ICP-AES. Calcium phosphate powder: OHAp, DCPD, beta-TCP and OCP were observed in the white powder form and in the photopolymerized adhesive monomer they scattered like dispersed fillers in resin composite. In elemental analysis, CaKalpha showed a relatively high concentration in relation to PKalpha. In elution analysis, each calcium phosphate showed different elution of Ca and P. But Mg was almost equal to the detection limit of ICP-AES. Namely it was suggested that reparative dentin formation was effectively promoted under the following conditions: a calcification promoting effect by direct contact of the calcium phosphate powder, an ionic effect of Ca and P eluted from the powder located in the vicinity of the exposed pulp and environmental pH change of the surface in exposed pulp.

Energy output reduction and surface alteration of quartz and sapphire tips following Er:YAG laser contact irradiation for tooth enamel ablation.

BACKGROUND: Despite the recent increase in application of Er:YAG laser for various dental treatments, limited information is available regarding the contact tips. This study examined the changes in energy output and surface condition of quartz and sapphire contact tips after Er:YAG laser contact irradiation for tooth enamel ablation. MATERIALS AND METHODS: Ten sets of unused quartz or sapphire contact tips were employed for contact irradiation to sound enamel of extracted teeth. The teeth were irradiated with Er:YAG laser at approximately 75 J/cm(2)/pulse and 20 Hz under water spray for 60 minutes. The energy output was measured before and every 5 minutes after irradiation, and the changes in morphology and chemical composition of the contact surface were analyzed. RESULTS: The energy output significantly decreased with time in both tips. The energy output from the sapphire tips was generally higher on average than that of the quartz. The contact surfaces of all the used quartz tips were concave and irregular. Most of the sapphire tips also appeared rough with crater formation and fractures, except for a few tips in which a high energy output and the original smooth surface were maintained. Spots of melted tooth substances were seen attached to the surface of both tips. CONCLUSION: In contact enamel ablation, the sapphire tip appeared to be more resistant than the quartz tip. The quartz tips showed similar patterns of energy reduction and surface alteration, whereas the sapphire tips revealed a wider and more characteristic variation among tips. Lasers Surg. Med. 41:595-604, 2009. (c) 2009 Wiley-Liss, Inc.

[Perioperative nutrition for gastrointestinal surgery].

In elective gastrointestinal (GI) surgery, the patients' nutritional status should be assessed and if protein-energy malnutrition exists, preoperative nutritional support should be scheduled 7 to 14 days before surgery. In malnourished patients in particular, preoperative nutrition with total parenteral nutrition (TPN) reduces postoperative complication rates of infection. Preoperative enteral nutrition (EN) is considered to be as effective as TPN in improving postoperative surgical outcome. Many prospective randomized trials or meta-analyses comparing postoperative EN and TPN have revealed that postoperative EN improves surgical outcomes and lowers postoperative complication rates of infection to a degree similar to TPN. Although two recent prospective multicenter randomized trials in malnourished patients undergoing elective GI cancer surgery are controversial, no evidence that EN was less effective than TPN was recognized. Thus postoperative EN, prior to TPN, is recommended in patients with malnutrition or insufficient oral intake for 7 days or more after surgery. When TPN is administered, hyperglycemia due to overfeeding should be carefully controlled. Patients who undergo distal gastrectomy or colectomy can start oral intake 3 to 4 days after surgery, with pertinent peripheral infusion. Immunonutrition containing immune-enhancing nutrients such as arginine, n-3 polyunsaturated fatty acid, glutamine, etc., especially administered preoperatively, is a promising nutritional therapy for reducing postoperative infectious complications.