Validation of a manual headspace gas chromatography method for determining volatile compounds in biological fluids

Background: We report the validation of a method for the determination of acetaldehyde, acetone, methanol, and ethanol in biological fluids using manual headspace sample introduction and an acetonitrile internal standard. Method: This method uses a capillary column (I = 30 m, I.D. = 0.25 mm, dF = 0.25 mu m) installed in a gas chromatography-flame ionization detector (GC-FID) apparatus with a run time of 7.5 minutes. Results: Analysis of the retention times and the resolution of the analyte peaks demonstrated excellent separation without widening of the peaks. Precision and accuracy were good (interassay precision < 15% and recovery between 85% and 115%) in both blood and urine. Conclusion: The method was linear (r > 0.09) over the analytical measurement range (AMR) of each analyte.

Validation of ACB in vitro and in vivo as a biomagnetic method for measuring stomach contraction

Background The aim of this study was to validate a biomagnetic method (alternate current biosusceptometry, ACB) for monitoring gastric wall contractions in rats. Methods In vitro data were obtained to establish the relationship between ACB and the strain-gauge (SG) signal amplitude. In vivo experiments were performed in pentobarbital-anesthetized rats with SG and magnetic markers previously implanted under the gastric serosa or after ingestion of magnetic material. Gastric motility was quantified from the tracing amplitudes and frequency profiles obtained by Fast Fourier Transform. Key Results The correlation between in vitro signal amplitudes was strong (R = 0.989). The temporal cross-correlation coefficient between the ACB and SG signal amplitude was higher (P < 0.0001) in the postprandial (88.3 +/- 9.1 V) than in the fasting state (31.0 +/- 16.9 V). Irregular signal profiles, low contraction amplitudes, and smaller signal-to-noise ratios explained the poor correlation between techniques for fasting-state recordings. When a magnetic material was ingested, there was also strong correlation in the frequency and signal amplitude and a small phase-difference between the techniques. The contraction frequencies using ACB were 0.068 +/- 0.007 Hz (postprandial) and 0.058 +/- 0.007 Hz (fasting) (P < 0.002) and those using SG were 0.066 +/- 0.006 Hz (postprandial) and 0.059 +/- 0.008 Hz (fasting) (P < 0.005). Conclusions & Inferences In summary, ACB is reliable for monitoring gastric wall contractions using both implanted and ingested magnetic materials, and may serve as an accurate and sensitive technique for gastrointestinal motility studies.

Dose-dependent beneficial hemodynamic effects of BAY 41-2272 in a canine model of acute pulmonary thromboembolism

The current therapy of acute pulmonary embolism is focused on removing the mechanical obstruction of the pulmonary vessels. However, accumulating evidence suggests that pulmonary vasoconstriction drives many of the hemodynamic changes found in this condition. We examined the effects of stimulation of soluble guanylate cyclase with BAY 41-2272 (5-Cyclopropyl-2-[1-(2-fluoro-benzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-pyrimidin-4-ylamine) in an anesthetized dog model of acute pulmonary embolism. Hemodynamic and arterial blood gas evaluations were performed in non-embolized dogs treated with vehicle (N = 5), and in embolized dogs (intravenous injections of microspheres) that received BAY 41-2272 intravenously in doses of 0.03, 0.1, 0.3, and 1 mg/kg/h or vehicle (1 ml/kg/h of 1.13% ethanol in saline, volume/volume). Plasma cGMP and thiobarbituric acid reactive substances concentrations were determined using a commercial enzyme immunoassay and a fluorometric method, respectively. The infusion of BAY 41-2272 resulted in a decrease in pulmonary artery pressure by similar to 29%, and in pulmonary vascular resistance by similar to 46% of the respective increases induced by lung embolization (both P<0.05). While the higher doses of BAY 41-2272 produced no additional effects on the pulmonary circulation, they caused significant arterial hypotension and reduction in systemic vascular resistance (both P<0.05). Although BAY 41-2272 increased cGMP concentrations (P<0.05), it did not affect the hypoxemia and the increased oxidative stress caused by lung embolization. These results suggest that stimulation of soluble guanylate cyclase with low (but not high) doses of BAY 41-2272 produces selective pulmonary vasodilation during acute pulmonary embolism. The dose-dependent systemic effects produced by BAY 41-2272, however, may limit its usefulness in larger doses. (C) 2007 Elsevier B.V. All rights reserved.

Proposal for a Trigonometric Method to Evaluate the Abduction Angle of the Lower Limbs in Neonates

It is difficult to precisely measure articular arc movement in newborns using a goniometer. This article proposes an objective method based on trigonometry for the evaluation of lower limb abduction. With the newborn aligned in the dorsal decubitus position, 2 points are marked at the level of the medial malleolus, one on the sagittal line and the other at the end of the abduction. Using the right-sided line between these 2 points and a line from the medial malleolus to the reference point at the anterior superior iliac spine or umbilical scar, an isosceles triangle is drawn, and half of the inferential abduction angle is obtained by calculating the sine. Twenty healthy full-term newborns comprise the study cohort. Intersubject and intrasubject variability among the abduction angle values (mean [SD], 37 degrees [4]degrees) is low. This method is advantageous because the measurement is precise and because the sine can be used without approximation.

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.

FURTHER INSIGHTS TOWARD VITAMIN C DETERMINATION AND STABILITY. PROPOSAL OF A NEW QUANTIFICATION METHOD

This work aimed at an evaluation of the classical iodine method for quantification of vitamin C (L-ascorbic acid) in fruit juices, as well as at a search into the stability of this so popular vitamin under different conditions of pH, temperature and light exposition, in addition to a proposal of a new quantification method. Our results point to the persistent reversibility of the blue color of the starch-triiodide complex at the end point when using the classical iodine titration, and the overestimation of the true vitamin concentration in fruit juices. A new quantification method is proposed in order to overcome this problem. Surprising conclusions were obtained regarding the controversial stability of L-ascorbic acid toward atmospheric oxygen, at low pH, even in fruit juice and at room temperature, showing that the major problem concerned with aging of fruit juices is proliferation of microorganisms rather than expontaneous oxidation of L-ascorbic acid.

Temporal evolution of epithelial, vascular and interstitial lung injury in an experimental model of idiopathic pulmonary fibrosis induced by butyl-hydroxytoluene

This study was undertaken to test whether the structural remodelling of pulmonary parenchyma can be sequentially altered in a model and method that demonstrate the progression of the disease and result in remodelling within the lungs that is typical of idiopathic pulmonary fibrosis. Three groups of mice were studied: (i) animals that received 3-5-di-tert-butyl-4-hydroxytoluene (BHT) and were killed after 2 weeks (early BHT = 9); (ii) animals that received BHT and were killed after 4 weeks (late BHT = 11); (iii) animals that received corn oil solution (control = 10). The mice were placed in a ventilated Plexiglas chamber with a mixture of pure humidified oxygen and compressed air. Lung histological sections underwent haematoxylin-eosin, immunohistochemistry (epithelial, endothelial and immune cells) and specific staining (collagen/elastic fibres) methods for morphometric analysis. When compared with the control group, early BHT and late BHT groups showed significant decrease of type II pneumocytes, lower vascular density in both and higher endothelial activity. CD4 was increased in late BHT compared with early and control groups, while CD8, macrophage and neutrophil cells were more prominent only in early BHT. The collagenous fibre density were significantly higher only in late BHT, whereas elastic fibre content in late BHT was lower than that in control group. We conclude that the BHT experimental model is pathologically very similar to human usual interstitial pneumonia. This feature is important in the identification of animal models of idiopathic pulmonary fibrosis that can accurately reflect the pathogenesis and progression of the human disease.

Use of lignin extracted from different plant sources as standards in the spectrophotometric acetyl bromide lignin method

A nongravimetric acetyl bromide lignin (ABL) method was evaluated to quantify lignin concentration in a variety of plant materials. The traditional approach to lignin quantification required extraction of lignin with acidic dioxane and its isolation from each plant sample to construct a standard curve via spectrophotometric analysis. Lignin concentration was then measured in pre-extracted plant cell walls. However, this presented a methodological complexity because extraction and isolation procedures are lengthy and tedious, particularly if there are many samples involved. This work was targeted to simplify lignin quantification. Our hypothesis was that any lignin, regardless of its botanical origin, could be used to construct a standard curve for the purpose of determining lignin concentration in a variety of plants. To test our hypothesis, lignins were isolated from a range of diverse plants and, along with three commercial lignins, standard curves were built and compared among them. Slopes and intercepts derived from these standard curves were close enough to allow utilization of a mean extinction coefficient in the regression equation to estimate : lignin concentration in any plant, independent of its botanical origin. Lignin quantification by use of a common regression equation obviates the steps of lignin extraction, isolation, and standard curve construction, which substantially expedites the ABL method. Acetyl bromide lignin method is a fast, convenient analytical procedure that may routinely be used to quantify lignin.

A method for simultaneous detection and identification of Brazilian dog- and vampire bat-related rabies virus by reverse transcription loop-mediated isothermal amplification assay

At present, the sporadic occurrence of human rabies in Brazil can be attributed primarily to dog- and vampire bat-related rabies viruses. Reverse transcription loop-mediated isothermal amplification (RT-LAMP) was employed as a simultaneous detection method for both rabies field variants within 60 min. Vampire bat-related rabies viruses could be distinguished from dog variants by digesting amplicons of the RT-LAMP reaction using the restriction enzyme Alwl. Amplification and digestion could both be completed within 120 min after RNA extraction. In addition, the RI-LAMP assay also detected rabies virus in isolates from Brazilian frugivorous bats and Ugandan dog, bovine and goat samples. In contrast, there were false negative results from several Brazilian insectivorous bats and all of Chinese dog, pig, and bovine samples using the RI-LAMP assay. This study showed that the RT-LAMP assay is effective for the rapid detection of rabies virus isolates from the primary reservoir in Brazil. Further improvements are necessary so that the RT-LAMP assay can be employed for the universal detection of genetic variants of rabies virus in the field. (C) 2010 Elsevier B.V. All rights reserved.

Evaluation of three different adhesive systems using a bacterial method to develop secondary caries in vitro

Purpose: To assess the effects of three different dental adhesive systems on the formation of secondary root caries, in vitro, with a standardized interfacial gap in a filled cavity model. Methods: 40 sound human molars were selected and randomly assigned to four experimental groups: Clearfil SE Bond (CSEB), Xeno III (X-III), Scotchbond Multi-Purpose Plus (SBMP) and negative control (NC) without an adhesive system. After the standardized Class V cavity preparations on the buccal and lingual surfaces, restorations were placed with resin composite (Filtek Z250) using a standardized interfacial gap, using a 3 x 2 mm piece of 50 mu m metal matrix. The teeth were sterilized with gamma irradiation and exposed to a cariogenic challenge using a bacterial system with Streptococcus mutans. Depth and extension of wall lesions formed and the depth of outer lesions were measured by software coupled with light microscopy. Results: For wall lesion extension the ANOVA test showed differences between groups except between X-HI and SBMP (P= 0.294). The Tukey`s test of confidence intervals indicated smaller values for the CSEB group than for the others. For wall lesion depth the CSEB group also presented the smallest mean values of wall lesion depth when compared to the others (P< 0.0001) for all comparisons using Tukey`s test. Regarding outer lesion depth, all adhesives showed statistically similar behavior. SEM evaluation of the morphologic appearance of caries lesions confirmed the statistical results showing small caries lesion development for cavities restored with CSEB adhesive system, which may suggest that this adhesive system interdiffusion zone promoted a good interaction with subjacent dentin protecting the dental tissues from recurrent caries. (Am J Dent 2010;23:93-97).

Morphological assessment of dentine and cementum following apicectomy with Zekrya burs and Er:YAG laser associated with direct and indirect Nd:YAG laser irradiation

Objectives. This study aimed to assess the apical surface morphology of maxillary central incisors resected 3.0 mm from the tooth apex using Zekrya burs or Er:YAG laser, with or without subsequent direct Nd:YAG laser irradiation (apical and buccal surfaces) and indirect irradiation (palatal surface). Study design. Forty maxillary central incisors were instrumented and obturated. The roots were divided into 4 groups according to the root resection method (Zekrya bur or Er: YAG laser -1.8 W, 450 mJ, 4 Hz, 113 J/cm(2)) and further surface treatment (none or Nd: YAG laser -2.0 W, 100 mJ, 20 Hz, 124 J/cm(2)). The teeth were prepared for SEM analysis. Scores ranging from 1 to 4 were attributed to cut quality and morphological changes. The data were analyzed by the Kruskal-Wallis test and by Dunn`s test. Results. SEM images showed irregular surfaces on the apical portions resected with Zekrya burs, with smear layer and grooves in the resected dentine and slight gutta-percha displacement and plasticization. On the other hand, apicectomies carried out with Er: YAG laser showed morphological changes compatible with ablated dentine, with rough surfaces and craters. In spite of the presence of plasticized gutta-percha, with the presence of bubbles, an irregular adaptation of the filling material to the root walls was also observed. Direct Nd: YAG laser irradiation of the apical and buccal surfaces of the resected roots resulted in areas of resolidification and fusion in the dentine and cementum, with a vitrified aspect; indirect Nd: YAG laser irradiation of the palatal surfaces yielded a lower number of changes in the cementum, with irregular resolidification areas. Conclusions. There were no differences in terms of cut quality between the use of burs and Er: YAG laser or between the 2 surfaces (apical and buccal) treated with Nd: YAG laser with direct irradiation. However, morphological changes were significantly less frequent on surfaces submitted to indirect irradiation (palatal) when compared with those directly irradiated. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010; 109: e77-e82)

Bacterial Adhesion on Smooth and Rough Titanium Surfaces After Treatment With Different Instruments

Background: Newly formed biofilm after implant debridement may challenge the long-term stability of peri-implant therapy. This in vitro study aimed to assess the roughness and adherence of Streptococcus sanguinis after treatment of smooth and rough titanium surfaces with an erbium-doped: yttrium, aluminum, and garnet (Er:YAG) laser, metal and plastic curets, and an air-powder abrasive system. Methods: Forty titanium disks with smooth-machined surfaces and 40 with sand-blasted and acid-etched surfaces were divided into the following treatment groups: Er:YAG laser; plastic curet; metal curet, and air-powder abrasive system. The surface roughness (roughness average [Raj) before and after treatments was determined using a profilometer. S. sanguinis (American Type Culture Collection 10556) was grown on treated and untreated specimens, and the amounts of retained bacteria on the surfaces were measured by the culture method. Rough and smooth surfaces with and without a suspension of S. sanguinis were also analyzed using scanning electron microscopy (SEM). Results: For smooth surfaces, the roughest surfaces were produced by metal curets (repeated - measures analysis of variance [ANOVA] and Tukey test; P<0.05). The rough-surface profile was not altered by any of the treatments (repeated-measures ANOVA; P>0.05). Rough surfaces treated with metal curets and air-powder abrasion showed the lowest level of bacteria] adhesion (two-way ANOVA and Tukey test; P<0.05). SEM analysis revealed distinct surface profiles produced by all devices. Conclusions: Metal curets are not recommended for smooth titanium surface debridement due to severe texture alteration. Rough surfaces treated with a metal curet and the air-powder abrasive system were less susceptible to bacterial adhesion, probably due to texture modification and the presence of abrasive deposits. J Periodontol 2009;80: 1824-1832.

Erbium, chromium : yttrium scandium gallium garnet laser for caries removal: influence on bonding of a self-etching adhesive system

This study evaluated the influence of the dental substrates obtained after the use of different caries removal techniques on bonding of a self-etching system. Forty, extracted, carious, human molars were ground to expose flat surfaces containing caries-infected dentine surrounded by sound dentine. The caries lesions of the specimens were removed or not (control-G1) either by round steel burs and water-cooled, low speed, handpiece (G2), or by irradiation with an erbium, chromium:yttrium scandium gallium garnet (Er,Cr:YSGG) laser (2W, 20 Hz, 35.38 J/cm(2), fiber G4 handpiece with 0.2826 mm(2), non-contact mode at a 2 mm distance, 70% air/20% water-G3) or using a chemo-mechanical method (Carisolv-G4). Caries-infected, caries-affected and sound dentines were submitted to a bonding system followed by construction of a resin-based composite crown. Hour-glass shaped samples were obtained and submitted to a micro-tensile bond test. The bond strength data were compared by analysis of variance (ANOVA), complemented by Tukey`s test (P <= 0.05). The samples of sound dentine presented higher bond strengths than did samples of caries-affected dentine, except for the groups treated with the Er,Cr:YSGG laser. The highest bond strengths were observed with the sound dentine treated with burs and Carisolv. The bond strengths to caries-affected dentine were similar in all groups. Additionally, bonding to caries-affected dentine of the Er,Cr:YSGG laser and Carisolv groups was similar to bonding to caries-infected dentine. Thus, caries-affected dentine is not an adequate substrate for adhesion. Moreover, amongst the caries removal methods tested, the Er,Cr:YSGG laser irradiation was the poorest in providing a substrate for bonding with the tested self-etching system.

Different air-water spray regulations affect the healing of Er,Cr:YSGG laser incisions

Surgeries performed with high-intensity laser devices may be improved with accurate protocols, including the air-water spray regulation. Thus, this study sought to investigate the healing process of wounds made on the dorsum of rat tongues using an Er,Cr:YSGG laser device with different air-water spray regulations. The incisions were made on the dorsum of Wistar rat tongues using an Er,Cr:YSGG laser with three different air-water spray regulations (100/0%, 50/50%, 11/7%). Scalpel incisions functioned as controls. The sacrifices occurred between 0 and 14 days after surgery. Morphological, histological, and immunohistochemical (fibronectin and type III collagen) analysis of the wounds were performed. The air-water spray regulation influenced wound healing and the inflammatory response, especially in the earlier stages. Incisions performed using the 100/0% air/water spray regulation had the worst results, expressing a greater amount of fibronectin and type III collagen. The 50/50% air/water spray regulation brought in a non-clear surgical field and poor laser interaction with the tissue. The 11/7% air/water spray regulation showed the best clinical results and less pronounced histological events. According to the results encountered, the air-water spray should be regulated to improve surgery.

Effect of the C-factor and Dentin Preparation Method in the Bond Strength of a Mild Self-etch Adhesive

This study evaluated the effect of the C-factor and dentin preparation method (DPM) in the bond strength (BS) of a mild self-etch adhesive; the study also observed the SEM superficial aspects of the corresponding smear layer. For purposes of this study, 25 molars (n=5) were used in a bond strength test. The molars were divided into two parts (buccal and lingual): one part received a Class V cavity (C-factor=3) and the other received a flat surface (C-factor=0) with the same bur type (coarse diamond or carbide bur and fine diamond or carbide bur), both within the same dentin depth. Five teeth were prepared with wet 60-grit and 600-grit SiC papers. After restoration with Clearfil SE Bond, microtensile beans (0.8 mm(2)) were prepared and tested after 24 hours in a universal testing machine (0.5 mm/minute). An additional two teeth for each DPM were prepared for SEM evaluation of the smear layer superficial aspects. The BS values were submitted to one-way ANOVA, considering only the DPM (flat surfaces) and two-way ANOVA (C-Factor x DPM, considering only burs) with p=0.05. Although the DPM in the flat surfaces was not significant, the standard deviations of carbide bur-prepared specimens were markedly lower. The BS was significantly lower in cavities. The fine carbide bur presented the most favorable smear layer aspect. It was concluded that different dentin preparation methods could not prevent the adverse effect in bond strength of a high C-factor. A coarse cut carbide bur should be avoided prior to a mild self-etch adhesive, because it adversely affected bond strength. In contrast, a fine cut carbide bur provided the best combination: high bond strength with low variability, which suggests a more reliable bond strength performance.