Effects of a divided high loading dose of caffeine on circulatory variables in preterm infants

BACKGROUND: A single high loading dose of 25 mg/kg caffeine has been shown to be effective for the prevention of apnoea, but may result in considerable reductions in blood flow velocity (BFV) in cerebral and intestinal arteries. OBJECTIVE: To assess the effects of two loading doses of 12.5 mg/kg caffeine given four hours apart on BFV in cerebral and intestinal arteries, left ventricular output (LVO), and plasma caffeine concentrations in preterm infants. DESIGN: Sixteen preterm neonates of <34 weeks gestation were investigated one hour after the first oral dose and one, two, and 20 hours after the second dose by Doppler sonography. RESULTS: The mean (SD) plasma caffeine concentrations were 31 (7) and 29 (7) mg/l at two and 20 hours respectively after the second dose. One hour after the first dose, none of the circulatory variables had changed significantly. One hour after the second caffeine dose, mean BFV in the internal carotid artery and anterior cerebral artery showed significant reductions of 17% and 19% (p = 0.01 and p = 0.003 respectively). BFV in the coeliac artery and superior mesenteric artery, LVO, PCO2, and respiratory rate had not changed significantly. Total vascular resistance, calculated as the ratio of mean blood pressure to LVO, had increased significantly one and two hours after the second dose (p = 0.049 and p = 0.023 respectively). CONCLUSION: A divided high loading dose of 25 mg/kg caffeine given four hours apart had decreased BFV in cerebral arteries after the second dose, whereas BFV in intestinal arteries and LVO were not affected.

Detection of approximal caries with a new laser fluorescence device

The laser device DIAGNOdent developed for the detection of occlusal caries has limited value on approximal surfaces. The aim of this study was to develop and to test a new laser fluorescence (LF) device for the detection of approximal caries. Light with a wavelength of 655 nm was transported to the approximal surface using two different sapphire fibre tips. Seventy-five teeth were selected from a pool of extracted permanent human molars, frozen at -20 degrees C until use. Before being measured, they were defrosted, cleaned and calculus was removed with a scaler. The molars were set in blocks simulating the contact area of adults. Bitewing radiographs were obtained using Kodak Insight films. After two independent assessments with the new LF device, the teeth were histologically prepared, and assessed for caries extension. Using the laser, specificity values for D1 threshold (outer half of enamel), D2 threshold (inner half of enamel), D3 threshold (dentine) ranged between 0.81 and 0.93, sensitivity between 0.84 and 0.92 with no difference between the two tips. Bitewing radiography showed an inferior performance compared to LF (p<0.05). Intraex aminer reproducibility was high (kappa>.74). The new LF system might be a useful additional tool in detecting approximal caries. Because of its good reproducibility, it could be used to monitor caries regression or progression on approximal surfaces.

Performance of a new laser fluorescence device for the detection of occlusal caries in vitro

The new device DIAGNOdent pen based on red laser light induced fluorescence was introduced for the detection of approximal and occlusal caries. The aim of this study was to test its performance on occlusal surfaces. The new device comes with two different sapphire fibre tips: a cylindrical tip and a conical tip. The two new sapphire fibre tips were used and compared with the tip currently available with DIAGNOdent (DD). METHODS: The teeth were selected from a pool of extracted permanent human molars, which were stored frozen at -20 degrees C, until use. Prior to being measured the teeth were defrosted and cleaned. One hundred and nineteen teeth were selected and measured with the old tip and with the two new tips of the new device by two independent assessments. The teeth were histologically prepared and assessed for caries extension. RESULTS: Specificity values for D(1), D(2) and D(3) ranged between 0.69 and 0.89, sensitivity between 0.78 and 0.96. There were no statistically significant differences obtained between the two tips of the new and the one tip of the old device (p>0.05). Intra-examiner reliability with kappa values of >0.83 was high. CONCLUSIONS: In this study, the new laser fluorescence device performed on occlusal surfaces as well as the available device.

Calcium indicator loading of neurons using single-cell electroporation

Studies of subcellular Ca(2+) signaling rely on methods for labeling cells with fluorescent Ca(2+) indicator dyes. In this study, we demonstrate the use of single-cell electroporation for Ca(2+) indicator loading of individual neurons and small neuronal networks in rat neocortex in vitro and in vivo. Brief voltage pulses were delivered through glass pipettes positioned close to target cells. This approach resulted in reliable and rapid (within seconds) loading of somata and subsequent complete labeling of dendritic and axonal arborizations. By using simultaneous whole-cell recordings in brain slices, we directly addressed the effect of electroporation on neurons. Cell viability was high (about 85%) with recovery from the membrane permeabilization occurring within a minute. Electrical properties of recovered cells were indistinguishable before and after electroporation. In addition, Ca(2+) transients with normal appearance could be evoked in dendrites, spines, and axonal boutons of electroporated cells. Using negative-stains of somata, targeted single-cell electroporation was equally applicable in vivo. We conclude that electroporation is a simple approach that permits Ca(2+) indicator loading of multiple cells with low background staining within a short amount of time, which makes it especially well suited for functional imaging of subcellular Ca(2+) dynamics in small neuronal networks.

Fiberoptic system for recording dendritic calcium signals in layer 5 neocortical pyramidal cells in freely moving rats

Calcium influx into the dendritic tufts of layer 5 neocortical pyramidal neurons modifies a number of important cellular mechanisms. It can trigger local synaptic plasticity and switch the firing properties from regular to burst firing. Due to methodological limitations, our knowledge about Ca2+ spikes in the dendritic tuft stems mostly from in vitro experiments. However, it has been speculated that regenerative Ca2+ events in the distal dendrites correlate with distinct behavioral states. Therefore it would be most desirable to be able to record these Ca2+ events in vivo, preferably in the behaving animal. Here, we present a novel approach for recording Ca2+ signals in the dendrites of populations of layer 5 pyramidal neurons in vivo, which ensures that all recorded fluorescence changes are due to intracellular Ca2+ signals in the apical dendrites. The method has two main features: 1) bolus loading of layer 5 with a membrane-permeant Ca2+ dye resulting in specific loading of pyramidal cell dendrites in the upper layers and 2) a fiberoptic cable attached to a gradient index lens and a prism reflecting light horizontally at 90 degrees to the angle of the apical dendrites. We demonstrate that the in vivo signal-to-noise ratio recorded with this relatively inexpensive and easy-to-implement fiberoptic-based device is comparable to conventional camera-based imaging systems used in vitro. In addition, the device is flexible and lightweight and can be used for recording Ca2+ signals in the distal dendritic tuft of freely behaving animals.

Influence of beveling and ultrasound application on marginal adaptation of box-only Class II (slot) resin composite restorations

A laboratory study was performed to assess the influence of beveling the margins of cavities and the effects on marginal adaptation of the application of ultrasound during setting and initial light curing. After minimal access cavities had been prepared with an 80 microm diamond bur, 80 box-only Class II cavities were prepared mesially and distally in 40 extracted human molars using four different oscillating diamond coated instruments: (A) a U-shaped PCS insert as the non-beveled control (EMS), (B) Bevelshape (Intensiv), (C) SonicSys (KaVo) and (D) SuperPrep (KaVo). In groups B-D, the time taken for additional bevel finishing was measured. The cavities were filled with a hybrid composite material in three increments. Ultrasound was also applied to one cavity per tooth before and during initial light curing (10 seconds). The specimens were subjected to thermomechanical stress in a computer-controlled masticator device. Marginal quality was assessed by scanning electron microscopy and the results were compared statistically. The additional time required for finishing was B > D > C (p < or = 0.05). In all groups, thermomechanical loading resulted in a decrease in marginal quality. Beveling resulted in higher values for "continuous" margins compared with that of the unbeveled controls. The latter showed better marginal quality at the axial walls when ultrasound was used. Beveling seems essential for good marginal adaptation but requires more preparation time. The use of ultrasonic vibrations may improve the marginal quality of unbeveled fillings and warrants further investigation.

Immediate loading of single SLA implants: drilling vs. osteotomes for the preparation of the implant site

OBJECTIVES: To evaluate whether or not preparation of the implant site with osteotomes instead of drilling may improve peri-implant bone density and/or osseointegration, and whether or not this further improves the predictability of immediate loading of SLA implants. MATERIAL AND METHODS: The second, third, and fourth premolars were extracted in both sides of the mandible in six dogs, and after at least 3 months four SLA implants were inserted into each side of the jaw. In three animals, the implant sites were prepared by means of osteotomes, while standard stepwise drilling was used in the remaining animals. In each side of the jaw, two non-adjacent implants were restored with single crowns 4 days after installation, while the remaining two implants were left without crowns to serve as non-loaded controls. After 2, 4, or 12 weeks of loading, specimens including the implants and surrounding tissues were obtained and processed for histologic analysis of undecalcified sections. RESULTS: All implants placed with osteotomes were lost (five before delivery of the crowns and the rest during the first week after loading). None of the conventionally inserted implants, however, was lost, and histomorphometrical analysis revealed similar soft- and hard peri-implant tissue characteristics at immediately loaded and non-loaded implants at all observation times. Average bone-to-implant contact was 59-72% at immediately loaded implants vs. 60-63% at non-loaded ones. CONCLUSION: Preparation of the implant site by means of osteotomes had a deleterious effect on osseointegration, while immediate loading of single, free-standing, SLA implants following a conventional surgical protocol did not jeopardize their osseointegration.

Safety of ondansetron loading doses in children with cancer

INTRODUCTION: In highly emetogenic chemotherapy, the recommended dose of the serotonin-receptor antagonist ondansetron (5 mg/m(2) q8h) may be insufficient to prevent chemotherapy-induced nausea and vomiting. In adults, ondansetron-loading doses (OLD) of 32 mg are safe. We aimed to evaluate in children the safety of an OLD of 16 mg/m(2) (top, 24 mg) i.v., followed by two doses of 5 mg/m(2) q8h. MATERIALS AND METHODS: This retrospective single-center study included all pediatric oncology patients having received >/=1 OLD between 2002 and 2005. Adverse events (AE) definitely, probably, or possibly related to OLD were studied, excluding AE not or unlikely related to the OLD. Associations between potential predictors and at least moderate AE were analyzed by mixed logistic regression. RESULTS: Of 167 patients treated with chemotherapy, 37 (22%) received 543 OLD. The most common AE were hypotension, fatigue, injection site reaction, headache, hot flashes/flushes, and dizziness. At least mild AE were described in 139 OLD (26%), at least moderate AE in 23 (4.2%), and severe AE in 5 (0.9%; exact 95% confidence interval [CI], 0.4-2.1). Life-threatening or lethal AE were not observed (0.0%; 0.0-0.6). At least moderate AE were significantly more frequent in female patients (odds ratio [OR] 3.5; 95% CI 1.4-8.8; p = 0.010), after erroneously given second OLD (17.0; 1.9-154; p = 0.012) and higher 24 h cumulative surface corrected dose (1.26 per mg/m(2); 1.06-1.51; p = 0.009). OLD given to infants below 2 years were not associated with more frequent AE. CONCLUSIONS: Ondansetron-loading doses of 16 mg/m(2) (top, 24 mg) i.v. seem to be safe in infants, children, and adolescents.

Alveolar distraction osteogenesis: a systematic review

This literature review was performed to analyse the outcomes of clinical studies of alveolar distraction osteogenesis (DO) listed by PUBMED between January 1996 and December 2006. A PUBMED search identified 128 articles on alveolar DO. Twenty articles covering 209 cases were analysed, considering location, device and procedural parameters, rate of augmentation, aspect of final implant placement and follow up. The mean latency period was 7.26+/-2.31 days, distraction rate 0.71+/-0.27 mm/day, rate of augmentation 6.88+/-2.52 mm and consolidation period 12.22+/-5.58 weeks. A total of 469 implants were placed and followed post loading for an average of 14.19+/-11.03 months, with a survival rate of 97%. Of the different procedural parameters, only the difference between mean consolidation period for failed (8.10+/-2.51 weeks) and successful (12.43+/-5.62 weeks) implants was statistically significant (P=0.01). Use of DO may be advantageous in terms of the success rate of implants placed in augmented sites, but there is still a lack of sufficient data based on long-term follow up. Future experimental studies should evaluate the application of different methods with a view to shortening the overall treatment period and improving the performance of implants placed in distracted alveolar ridges.

Minimized cardiopulmonary bypass combined with a smart suction device: the future of cardiopulmonary bypass?

OBJECTIVE: The standard heart-lung machine is a major trigger of systemic inflammatory response and the morbidity attributed to conventional extracorporeal circulation (CECC) is still significant. Reduction of blood-artificial surface contact and reduction of priming volume are principal aims in minimized extracorporeal circulation (MECC) cardiopulmonary bypass systems. The aim of this paper is to give an overview of the literature and to present our experience with the MECC-smart suction system. METHODS AND RESULTS: At our institution, 1799 patients underwent isolated coronary artery bypass grafting (CABG) surgery, 1372 with a MECC-smart suction system and 427 with CECC. All in-hospital data were assessed and the results were compared between the 2 groups. Patient characteristics and the distribution of EuroSCORE risk profile in our collective were similar between both groups. Average age in the MECC collective was 67.5 +/- 11.4 years and average EuroSCORE was 5.0 +/- 1.5. Average number of distal anastomoses was similar to the average number encountered in patients undergoing CABG surgery with CECC (3.3 +/- 1.0 for MECC versus 3.2 +/- 1.1 for CECC; P = ns). Myocardial protection is superior in MECC patients with lower postoperative maximal cTnI values (11.0 +/- 10.8 micromol/L for MECC versus 24.7 +/- 25.3 micromol/L for CECC; P < .05). Postoperative recovery was faster in patients operated on with the MECC-smart suction system and discharge from the hospital was earlier than for CECC patients (7.4 +/- 1.9 days for MECC versus 8.8 +/- 3.8 days for CECC; P < .05). CONCLUSIONS: The MECC-smart suction system is a safe perfusion technique for CABG surgery. In patients operated on with this system, the clinical outcome seems to be better than in patients operated on with CECC. This promising and less damaging perfusion technology has the potential to replace CECC systems in CABG surgery.

Acute device-based blood pressure reduction: electrical activation of the carotid baroreflex in patients undergoing elective carotid surgery

Carotid sinus baroreceptors are involved in controlling blood pressure (BP) by providing input to the cardiovascular regulatory centers of the medulla. The acute effect of temporarily placing an electrode on the carotid sinus wall to electrically activate the baroreflex was investigated. We studied 11 patients undergoing elective carotid surgery. Baseline BP was 146+30/66+/-17 mm Hg and heart rate (HR) 72+/-7 bpm (mean +/- standard deviation). An electrode was placed upon the carotid sinus and after obtaining a steady state baseline of BP and HR, an electric current was applied and increased in 1-volt increments. A voltage dependent and highly significant reduction in BP was observed which averaged 18+/-26* and 8.0+/-12 mm Hg for systolic BP and diastolic BP, respectively. Maximal reductions occurred at 4.4+/-1.2 V: 23+/-24 mm Hg*, 16+/-10 mm Hg* and 7+/-12 bpm* for systolic BP, diastolic BP and HR, respectively ( = p <.05). Thus, electrical stimulation of the carotid sinus activates the carotid baroreflex resulting in a reduction in BP and HR. This presents a proof of concept for device based baroreflex modulation in acute BP regulation and adds to the available data which provide a rationale for evaluating this system in the context of chronic BP reduction in hypertensive patients.