Trigger performance of mid-level ICU mechanical ventilators during assisted ventilation: a bench study

Objective: To compare the triggering performance of mid-level ICU mechanical ventilators with a standard ICU mechanical ventilator. Design: Experimental bench study. Setting: The respiratory care laboratory of a university-affiliated teaching hospital. Subject: A computerized mechanical lung model, the IngMar ASL5000. Interventions: Ten mid-level ICU ventilators were compared to an ICU ventilator at two levels of lung model effort, three combinations of respiratory mechanics (normal, COPD and ARDS) and two modes of ventilation, volume and pressure assist/control. A total of 12 conditions were compared. Measurements and main results: Performance varied widely among ventilators. Mean inspiratory trigger time was < 100 ms for only half of the tested ventilators. The mean inspiratory delay time (time from initiation of the breath to return of airway pressure to baseline) was longer than that for the ICU ventilator for all tested ventilators except one. The pressure drop during triggering (Ptrig) was comparable with that of the ICU ventilator for only two ventilators. Expiratory Settling Time (time for pressure to return to baseline) had the greatest variability among ventilators. Conclusions: Triggering differences among these mid-level ICU ventilators and with the ICU ventilator were identified. Some of these ventilators had a much poorer triggering response with high inspiratory effort than the ICU ventilator. These ventilators do not perform as well as ICU ventilators in patients with high ventilatory demand.

Changes in slow and fast alpha bands in subjects submitted to different amounts of functional electrostimulation

Objective: To examine the changes in slow (8-10 Hz)and fast (10-12 Hz) alpha bands of EEG in three groups of subjects submitted to different amounts of functional electrostimulation (FES). Our hypothesis is that different amounts of electrostimulation may cause different patterns of activation in the sensorimotor cortex. In particular, we expect to see an increase in alpha power due to habituation effects. We examine the two bands comprised by alpha rhythm (i.e., slow and fast alpha), since these two sub-rhythms are related to distinct aspects: general energy demands and specific motor aspects, respectively. Methods: The sample was composed of 27 students, both sexes, aging between 25 and 40 years old. The subjects were randomly distributed in three groups: control (n = 9), G24 (n = 9) and G36 (n = 9). A FES equipment (Neuro Compact-2462) was used to stimulate the right index finger extension. Simultaneously, the electroencephalographic signal was acquired. We investigated the absolute power in slow and fast alpha bands in the sensorimotor cortex. Results: The G36 indicated a significant increasing in absolute power values in lower and higher alpha components, respectively, when compared with the control group. Particularly, in the following regions: pre-motor cortex and primary motor cortex. Discussion: FES seems to promote cortical adaptations that are similar to those observed when someone learns a procedural task. FES application in the G36 was more effective in promoting such neural changes. The lower and higher components of alpha rhythms behave differently in their topographical distribution during FES application. These results suggest a somatotopic organization in primary motor cortex which can be represented by the fast alpha component. (C) 2008 Elsevier Ireland Ltd. All rights reserved.

The ""single-section"" Golgi method adapted for formalin-fixed human brain and light microscopy

The Golgi method has been used for over a century to describe the general morphology of neurons in the nervous system of different species. The ""single-section"" Golgi method of Gabbott and Somogyi (1984) and the modifications made by Izzo et al. (1987) are able to produce consistent results. Here, we describe procedures to show cortical and subcortical neurons of human brains immersed in formalin for months or even years. The tissue was sliced with a vibratome, post-fixed in a combination of paraformaldehyde and picric acid in phosphate buffer, followed by osmium tetroxide and potassium dicromate, ""sandwiched"" between cover slips, and immersed in silver nitrate. The whole procedure takes between 5 and 11 days to achieve good results. The Golgi method has its characteristic pitfalls but, with this procedure, neurons and glia appear well-impregnated, allowing qualitative and quantitative studies under light microscopy. This contribution adds to the basic techniques for the study of human nervous tissue with the same advantages described for the ""single-section"" Golgi method in other species; it is easy and fast, requires minimal equipment, and provides consistent results. (C) 2010 Elsevier B.V. All rights reserved.

A new proctoscope for transanal endoscopic operations

Transanal access is one of many currently used procedures for rectal cancer treatment. The techniques used for local excision include conventional transanal excision, posterior access, therapeutic colonoscopy and transanal endoscopic approaches. The aim of the present study was to present a new surgical proctoscope for the endoscopic transanal excision of rectal lesions. A cylindrical proctoscope with a diameter of 4 cm was devised and built. The end inserted into the anus has a bevelled aspect and rounded borders, allowing correct exposure of the anal lesion. The rectoscope is fixed to the anal border with surgical thread through perforations in the external end. A base screw holds a fibre-light which illuminates the operative field. Part of the equipment is a guide which is positioned inside the rectoscope on insertion into the anus. In operations utilizing this proctoscope, 17 adenomas, 25 adenocarcinomas, 1 carcinoid and 1 endometrioma were excised. The diameter of the lesions varied from 1 to 6 cm. The range of procedures that are possible with this new proctoscope are similar to those achieved with conventional techniques which, however, require more expensive equipment. Hence, the present study demonstrates that this newly devised low-cost proctoscope is an efficient tool for the transanal endoscopic excision of rectal lesions.

A randomized trial of 5 versus 7 French guiding catheters for transfemoral percutaneous coronary stent implantation

Comparative studies between 5 French guiding catheter and others of larger size using the transfemoral approach to coronary stenting have not been described. Coronary stent implantation was performed in 90 patients in a randomized trial. The primary end-point was to compare the incidence of successful uncomplicated stent implantation per lesion with the 5F and 7F guiding catheters. Patients were excluded for excessive vessel tortuosity or anticipated need for equipment not fitting through a 5 catheter. Baseline characteristics and the use of direct stenting did not differ between the two groups. The primary success rate was 97.8% per patient in both groups and 98% per lesion in the 5 French and 97.9% in the 7 French. Guiding catheter change was necessary in 1 patient in each group to successfully complete the procedure in both groups. The amount of contrast used was 63 +/- 27.3 mL in the 5 French and 76 +/- 25 mL in the 7 French groups (P < 0.05). Vascular complications and blood transfusions occurred somewhat more frequently in the 7 French group (P = 0.058). The manual compression time after sheath removal was 5.1 +/- 2.0 min and 8.0 +/- 4.3 min, respectively, in the 5 and 7 French groups (P < 0.01). In conclusion, the 5 French guiding catheters showed a similar success rate with coronary stenting when compared to the 7 French, but the amount of contrast used and manual compression time after sheath removal, as well as the rate of vascular and bleeding complications, were reduced in the 5 French group.

Evaluation of erythrocyte dysmorphism by light microscopy with lowering of the condenser lens: A simple and efficient method

Aim: To demonstrate that the evaluation of erythrocyte dysmorphism by light microscopy with lowering of the condenser lens (LMLC) is useful to identify patients with a haematuria of glomerular or non-glomerular origin. Methods: A comparative double-blind study between phase contrast microscopy (PCM) and LMLC is reported to evaluate the efficacy of these techniques. Urine samples of 39 patients followed up for 9 months were analyzed, and classified as glomerular and non-glomerular haematuria. The different microscopic techniques were compared using receiver-operator curve (ROC) analysis and area under curve (AUC). Reproducibility was assessed by coefficient of variation (CV). Results: Specific cut-offs were set for each method according to their best rate of specificity and sensitivity as follows: 30% for phase contrast microscopy and 40% for standard LMLC, reaching in the first method the rate of 95% and 100% of sensitivity and specificity, respectively, and in the second method the rate of 90% and 100% of sensitivity and specificity, respectively. In ROC analysis, AUC for PCM was 0.99 and AUC for LMLC was 0.96. The CV was very similar in glomerular haematuria group for PCM (35%) and LMLC (35.3%). Conclusion: LMLC proved to be effective in contributing to the direction of investigation of haematuria, toward the nephrological or urological side. This method can substitute PCM when this equipment is not available.

Loss of samples in the tissue microarray technique: comparison between slides using adhesive tape and silanized slides

The tissue microarray (TMA) technique allows multiple tissue samples in a single block. Commercial adhesive tape is used to avoid the loss of tissue samples during the immunostaining process. Few reports exist in the literature comparing the use of these adhesive tapes to other adhesive techniques. The objective of this study was to compare loss of sections adhered to slides using commercial adhesive tapes versus using silanized only slides. TMA was constructed with varying tissues using a fixed-base device (Beecher Instruments), placing 108 cylinders of 1 mm diameter in duplicate, spaced 1.2 mm apart. Section of 4 mu m were cut from the TMA block and adhered to 30 silanized slides and 30 commercial glass slides using adhesive tape, according to manufacturer`s recommendations. Vimentin immunoexpression was evaluated by immunohistochemistry. Antigenic recovery was realized in citrate buffer using a microwave oven. Cylinder loss in the immunohistochemical process was quantified and expressed as: total (>80%), almost complete (75-79%), or partial (50-74%). The commercial adhesive tape group presented lesser total loss (1.1 versus 6.4%), almost complete loss (2.2 versus 3.5%), and partial loss (2.1 versus 3.8%) than the silanized slide group (ANOVA, P < 0.05). The sum of total and almost complete losses in the silanized slide group was 9.9%, greater than the losses in slides using commercial adhesive tapes (3.3%) and less than reported and considered acceptable in the literature (10-30%). In conclusion, the use of silanized only slides presents very satisfactory results, requires less training, and reduces costs significantly, thus justifying their use in research.

Multiple imaging radiography at LNLS

An analyzer-based X-ray phase-contrast imaging (ABI) setup has been mounted at the Brazilian Synchrotron Light Laboratory (LNLS) for multiple imaging radiography (MIR) purposes. The algorithm employed for treating the MIR data collected at LNLS is described, and its reliability in extracting the distinct types of contrast that can be obtained with MIR is demonstrated by analyzing a test sample (thin polyamide wire). As a practical application, the possibility of studying ophthalmic tissues, corneal sequestra in this case, via MIR is investigated. (C) 2007 Elsevier B.V. All rights reserved.

Influence of laser irradiation on fiber post retention

The purpose of this in vitro study was to compare the bond strength between fiber post and laser-treated root canals. Forty single-rooted bovine teeth were endodontically treated and randomly divided into four groups of equal size according to the root canal treatment: group 1 conventional treatment (without laser irradiation); group 2 Nd:YAG laser (1.5 W, 10 Hz, 100 mJ); group 3 Er,Cr:YSGG laser (0.75 W, 20 Hz); and group 4 Nd:YAG + Er,Cr:YSGG lasers. The fiber posts were cemented with an adhesive system + resin cement, in accordance with the manufacturer`s instructions. A mini acrylic pipe was fixed on the coronal section of the post using a light-polymerized resin. Specimens were mounted on an acrylic pipe with a self-polymerized resin. Retention forces were determined using a universal testing machine (0.5 mm/min). Data were analyzed using one-way ANOVA and Tukey tests (p < 0.05). The post retention force in group 2 was found to be lower than that in the other experimental groups. Fractures were observed at the interface between the dentin and the resin in all groups. High-intensity lasers can be used in conventional endodontic treatment; however, root canal surface irradiation using the Nd:YAG laser was shown to negatively affect the post retention force.

Can the durability of one-step self-etch adhesives be improved by double application or by an extra layer of hydrophobic resin?

Objectives: This study evaluated the immediate and 6-month resin-dentin mu-bond strength (mu TBS) of one-step self-etch systems (Adper Prompt L-Pop [AD] 3M ESPE; Xeno III [XE] Dentsply De Trey; iBond [iB] Heraeus Kulzer) under different application modes. Materials and methods: Dentin oclusal surfaces were exposed by grinding with 600-grit SiC paper. The adhesives were applied according to the manufacturer`s directions [MD], or with double application of the adhesive layer [DA] or following the manufacturer`s directions plus a hydrophobic resin layer coating [HL]. After applying the adhesive resins, composite crowns were built up incrementally. After 24-h water storage, the specimens were serially sectioned in ""x"" and ""y"" directions to obtain bonded sticks of about 0.8 mm 2 to be tested immediately [IM] or after 6 months of water storage [6M] at a crosshead speed of 0.5 mm/min. The data from each adhesive was analyzed by a two-way repeated measures ANOVA (mode of application vs. storage time) and Tukey`s test (alpha = 0.05). Results: The adhesives performed differently according to the application mode. The DA and HL either improved the immediate performance of the adhesive or did not differ from the MD. The resin-dentin bond strength values observed after 6 months were higher when a hydrophobic resin coat was used than compared to those values observed under the manufacturer`s directions. Conclusions: The double application of one-step self-etch system can be safety performed however the application of an additional hydrophobic resin layer can improve the immediate resin-dentin bonds and reduce the degradation of resin bonds over time. (c) 2008 Elsevier Ltd. All rights reserved.

One-year stability of resin-dentin bonds created with a hydrophobic ethanol-wet bonding technique

Dentin bonding performed with hydrophobic resins using ethanol-wet bonding should be less susceptible to degradation but this hypothesis has never been validated. Objectives. This in vitro study evaluated stability of resin-dentin bonds created with an experimental three-step BisGMA/TEGDMA hydrophobic adhesive or a three-step hydrophilic adhesive after one year of accelerated aging in artificial saliva. Methods. Flat surfaces in mid-coronal dentin were obtained from 45 sound human molars and randomly divided into three groups (n = 15): an experimental three-step BisGMA/TEGDMA hydrophobic adhesive applied to ethanol (ethanol-wet bonding-GI) or water-saturated dentin (water-wet bonding-GII) and Adper Scotchbond Multi-Purpose [MP-GIII] applied, according to manufacturer instructions, to water-saturated dentin. Resin composite crowns were incrementally formed and light-cured to approximately 5 mm in height. Bonded specimens were stored in artificial saliva at 37 degrees C for 24h and sectioned into sticks. They were subjected to microtensile bond test and TEM analysis immediately and after one year. Data were analyzed with two-way ANOVA and Tukey tests. Results. MP exhibited significant reduction in microtensile bond strength after aging (24 h: 40.6 +/- 2.5(a); one year: 27.5 +/- 3.3(b); in MPa). Hybrid layer degradation was evident in all specimens examined by TEM. The hydrophobic adhesive with ethanol-wet bonding preserved bond strength (24 h: 43.7 +/- 7.4(a); one year: 39.8 +/- 2.7(a)) and hybrid layer integrity, with the latter demonstrating intact collagen fibrils and wide interfibrillar spaces. Significance. Coaxing hydrophobic resins into acid-etched dentin using ethanol-wet bonding preserves resin-dentin bond integrity without the adjunctive use of MMPs inhibitors and warrants further biocompatibility and patient safety`s studies and clinical testing. (C) 2009 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Effect of processing induced particle alignment on the fracture toughness and fracture behavior of multiphase dental ceramics

Objective. To investigate the processing induced particle alignment on fracture behavior of four multiphase dental ceramics (one porcelain, two glass-ceramics and a glass-infiltrated-alumina composite). Methods. Disks (empty set12mm x 1.1 mm-thick) and bars (3 mm x 4 mm x 20 mm) of each material were processed according to manufacturer instructions, machined and polished. Fracture toughness (K(IC)) was determined by the indentation strength method using 3-point bending and biaxial flexure fixtures for the fracture of bars and disks, respectively. Microstructural and fractographic analyses were performed with scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. Results. The isotropic microstructure of the porcelain and the leucite-based glass-ceramic resulted in similar fracture toughness values regardless of the specimen geometry. On the other hand, materials containing second-phase particles with high aspect ratio (lithium disilicate glass-ceramic and glass-infiltrated-alumina composite) showed lower fracture toughness for disk specimens compared to bars. For the lithium disilicate glass-ceramic disks, it was demonstrated that the occurrence of particle alignment during the heat-pressing procedure resulted in an unfavorable pattern that created weak microstructural paths during the biaxial test. For the glass-infiltrated-alumina composite, the microstructural analysis showed that the large alumina platelets tended to align their large surfaces perpendicularly to the direction of particle deposition during slip casting of green preforms. Significance. The fracture toughness of dental ceramics with anisotropic microstructure should be determined by means of biaxial testing, since it results in lower values. (C) 2009 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Effect of ion exchange on strength and slow crack growth of a dental porcelain

Objectives. To determine the effect of ion exchange on slow crack growth (SCG) parameters (n, stress corrosion susceptibility coefficient, and sigma(f0), scaling parameter) and Weibull parameters (m, Weibull modulus, and sigma(0), characteristic strength) of a dental porcelain. Methods. 160 porcelain discs were fabricated according to manufacturer`s instructions, polished through 1 mu m and divided into two groups: GC (control) and GI (submitted to an ion exchange procedure using a KNO(3) paste at 470 degrees C for 15 min). SCG parameters were determined by biaxial flexural strength test in artificial saliva at 37 degrees C using five constant stress rates (n =10). 20 specimens of each group were tested at 1 MPa/s to determine Weibull parameters. The SPT diagram was constructed using the least-squares fit of the strength data versus probability of failure. Results. Mean values of m and sigma(0) (95% confidence interval), n and sigma(f0) (standard deviation) were, respectively: 13.8 (10.1-18.8) and 60.4 (58.5 - 62.2), 24.1 (2.5) and 58.1 (0.01) for GC and 7.4 (5.3 -10.0) and 136.8 (129.1-144.7), 36.7 (7.3) and 127.9 (0.01) for GI. Fracture stresses (MPa) calculated using the SPT diagram for lifetimes of 1 day, 1 year and 10 years (at a 5% failure probability) were, respectively, 31.8, 24.9 and 22.7 for GC and 71.2, 60.6 and 56.9 for GI. Significance. For the porcelain tested, the ion exchange process improved strength and resistance to SCG, however, the material`s reliability decreased. The predicted fracture stress at 5% failure probability for a lifetime of 10 years was also higher for the ion treated group. (C) 009 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Subcritical crack growth in porcelains, glass-ceramics, and glass-infiltrated alumina composite for dental restorations

The objective was to compare fracture toughness (K(Ic)), stress corrosion susceptibility coefficient (n), and stress intensity factor threshold for crack propagation (K(I0)) of two porcelains [VM7/Vita (V) and d.Sign/Ivoclar (D)], two glass-ceramics [Empress/Ivolcar (E1) and Empress2/Ivlocar (E2)] and a glass-infiltrated alumina composite [In-Ceram Alumina/Vita (IC)]. Disks were constructed according to each manufacturer`s processing method, and polished before induction of cracks by a Vickers indenter. Crack lengths were measured under optical microscopy at times between 0.1 and 100 h. Specimens were stored in artificial saliva at 37A degrees C during the whole experiment. K(Ic) and n were determined using indentation fracture method. K(I0) was determined by plotting log crack velocity versus log K(I). Microstructure characterization was carried out under SEM, EDS, X-ray diffraction and X-ray fluorescence. IC and E2 presented higher K(Ic) and K(I0) compared to E1, V, and D. IC presented the highest n value, followed by E2, D, E1, and V in a decreasing order. V and D presented similar K(Ic), but porcelain V showed higher K(I0) and lower n compared to D. Microstructure features (volume fraction, size, aspect ratio of crystalline phases and chemical composition of glassy matrix) determined K(Ic). The increase of K(Ic) value favored the increases of n and K(I0).

Effect of the microstructure on the lifetime of dental ceramics

Objectives. To evaluate the effect of the microstructure on the Weibull and slow crack growth (SCG) parameters and on the lifetime of three ceramics used as framework materials for fixed partial dentures (FPDs) (YZ - Vita In-Ceram YZ; IZ - Vita In-Ceram Zirconia; AL - Vita In-Ceram AL) and of two veneering porcelains (VM7 and VM9). Methods. Bar-shaped specimens were fabricated according to the manufacturer`s instructions. Specimens were tested in three-point flexure in 37 degrees C artificial saliva. Weibull analysis (n = 30) and a constant stress-rate test (n = 10) were used to determine the Weibull modulus (m) and SCG coefficient (n), respectively. Microstructural and fractographic analyzes were performed using SEM. ANOVA and Tukey`s test (alpha = 0.05) were used to statistically analyze data obtained with both microstructural and fractographic analyzes. Results. YZ and AL presented high crystalline content and low porosity (0.1-0.2%). YZ had the highest characteristic strength (sigma(0)) value (911 MPa) followed by AL (488 MPa) and IZ (423 MPa). Lower sigma(0) values were observed for the porcelains (68-75 MPa). Except for IZ and VM7, m values were similar among the ceramic materials. Higher n values were found for YZ (76) and AL (72), followed by IZ (54) and the veneering materials (36-44). Lifetime predictions showed that YZ was the material with the best mechanical performance. The size of the critical flaw was similar among the framework materials (34-48 mu m) and among the porcelains (75-86 mu m). Significance. The microstructure influenced the mechanical and SCG behavior of the studied materials and, consequently, the lifetime predictions. (C) 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.