Current state of dynamic surgery. A literature review.

BACKGROUND: Recently, dental implant technology has been widely used for oral reconstruction. Dental implants are the treatment of choice for those patients with dental absences. An optimal implant placement is based on the prosthetic driven concept in order to achieve an aesthetic and functional restoration with a long-term prognosis. There are two types of guided implant surgery that are described in the literature: Static Guided Surgery (SGS) and Dynamic Guided Surgery (DGS). The aim of this study is to be aware of the current state of dynamic surgery and compare in the literature the discrepancies between planning and placement of dental implants. MATERIAL AND METHODS: The study consists of a bibliographic review on the topic. The research has been performed in the Medline/Pubmed of articles published by different professional associations and societies in the international context. RESULTS: Twenty two studies out of 100 articles from the initial search were finally included. Our results have been compared with other current available papers in the literature reviewed that obtained similar outcomes. CONCLUSIONS: Dynamic navigation shows a better accuracy and precision of implant placement. To corroborate the results of this review as well as to evaluate the different variables that could influence the accuracy of this technique, future randomized control trials will be needed.

Characterization and classification of the aroma of beer samples by means of an MS e-nose and chemometric tools.

An electronic nose based on coupling of headspace (HS) with a mass spectrometer (MS) has been used in this study to classify and characterize a series of beers according to their production site and chemical composition. With this objective, we analyzed 67 beers of the same brand and preparation process but produced in different factories. The samples were also subjected to sensory evaluation by a panel of experts. Linear discriminant analysis (LDA) was used as the classification technique and stepwise LDA based on Wilk's lambda criterion was used to select the most discriminating variables. To interpret the aroma characteristics of the beers from the m/z ions obtained, score and loading bi-plots were obtained by applying canonical variables. Because the beers analyzed were marketed with the same name and brand, we expected to be working with the same product irrespective of its origin. However, results from both sensory evaluation and use of the e-nose revealed differences between factories. With the e-nose it was possible to relate these differences to the presence (and abundance) of characteristic ions of different compounds typically found in beer. These results demonstrate that the HS-MS e-nose is not only an aroma sensor capable to classify and/or differentiate samples but it can also provide information about the compounds responsible for this differentiation.

Application of an electronic tongue based on FT-MIR to emulate the gustative mouthfeel "tannin amount" in red wines.

In this work, the ability of an electronic tongue based on Fourier-Transform Mid Infrared (FT-MIR) spectroscopy as a gustative sensor is assessed by emulating the responses of a tasting panel for the gustative mouthfeel "tannin amount". The FT-MIR spectra were modeled against the sensory responses evaluated in 37 red wines by means of partial least squares (PLS) regression models. In order to find the wavenumbers more correlated with the sensorial attribute and thus providing the best predictive models, six different variable selection techniques were tested. The iterative predictor weighting IPW-PLS technique showed the best results with the smallest RMSEC and RMSECV values (0.07 and 0.13, respectively) using 20 selected wavenumbers. The coincident wavenumbers selected by the six variable selection techniques were interpreted based on the absorption bands of tannin and then a calibration model using these wavenumbers was built to validate the interpretation made.

Comparative study of two chromatographic methods for quantifying 2,4,6-trichloranisole in wines.

Here we present the validation and the comparative study of two chromatographic methods for quantifying 2,4,6-trichloroanisole (TCA) in wines (red, rosé and white wines). The first method involves headspace solid-phase microextraction and gas chromatography with electron-capture detection (ECD). The evaluation of the performance parameters shows limit of detection of 0.3 ng l(-1), limit of quantification of 1.0 ng l(-1), recoveries around 100% and repeatability of 10%. The second one implies a headspace solid-phase microextraction and gas chromatography with mass spectrometric detection. The performance parameters of this second method are limit of detection of 0.2 ng l(-1), limit of quantification of 0.8 ng l(-1) and repeatability of 10.1%. From the comparative study we can state that both methods provide similar results and the differences between them are the better sensitivity of the GC-ECD method and the very shorter chromatogram running time of the GC-MS method. The two methods are able to quantify TCA below the sensorial threshold in red, rosé and white wines using just a calibration graph, thus they could be a very good tool for quality control in wineries.

Quantification of chloroanisoles in cork using headspace solid-phase microextraction and gas chromatography with electron capture detection.

Chloroanisoles can migrate from the cork stopper in wine bottles to the wine and give it a musty taint so it is important to find a method by which they can be determined. The aim of this paper is to develop a method for quantifying 2,4-dichloroanisole, 2,6-dichloroanisole, 2,4,6-trichloroanisole, 2,3,4,6-tetrachloroanisole and 2,3,4,5,6-pentachloroanisole in cork using headspace solid-phase microextraction and gas chromatography with electron capture detection. After we had prepared the cork standards that were so essential to the work we optimised the parameters that most influence headspace solid-phase microextraction: fibre coating, vial volume, cork, kind and volume of solvent to help the extraction, extraction temperature and time, ionic strength and stirring. The method quantifies the total amount of chloroanisoles in cork stoppers (natural, agglomerated, agglomerated with disks and sparkling wine stoppers), at suitable concentrations so that the capacity of these compounds to give wine a musty taint can be evaluated. The quantification limits are: 2,6-dichloroanisole (8.6 ng/g), 2,4,6-trichloroanisole (0.8 ng/g), 2,4-dichloroanisole (3.5 ng/g), 2,3,4,6-tetrachloroanisole (0.6 ng/g), 2,3,4,5,6-pentachloroanisole (0.8 ng/g). The other quality parameters are: recoveries (90.3-105.8%), repeatability (4-13% (RSD expressed)) and intermediate precision (5-14% (RSD expressed)).

A clinical comparison of two formulations of tobramycin 0.3% eyedrops in the treatment of acute bacterial conjunctivitis.

PURPOSE: To compare the safety and efficacy of a new enhanced viscosity ophthalmic formulation of tobramycin, given twice daily (BID), with the existing four times daily (QID) treatment regimen in patients with acute bacterial conjunctivitis. METHODS: This was a 12-day, multicenter, observer-masked, randomized, parallel group study. Patients received one drop of tobramycin 0.3% (3 mg/mL) enhanced viscosity ophthalmic solution BID or tobramycin 0.3% (3 mg/mL) ophthalmic solution QID in the affected eyes for 7 days. The primary efficacy variable was the percentage of patients with sustained cure/presumed bacterial eradication based on clinical judgment at the test-of-cure visit (Day 12). Pretherapy bacterial isolates were obtained and tested for susceptibility to tobramycin by determination of minimum inhibitory concentrations (MIC). RESULTS: A total of 276 patients were enrolled in the study and 203 of these were culture positive and attended all follow-up examinations. In this group, 98% of those treated with tobramycin enhanced viscosity ophthalmic solution and 99% of those treated with tobramycin 0.3% ophthalmic solution were categorized as having sustained cure/presumed eradication at the test-of-cure visit (p = 0.6037). Reported adverse events were not serious, mild to moderate in severity, and generally did not prevent continuation in the study. Several pre treatment pathogens demonstrated tobramycin resistance (MIC > 4 mg/mL). However, therapy with both treatments was effective in the majority of the cases. CONCLUSIONS: Tobramycin enhanced viscosity ophthalmic solution is well tolerated and has equivalent efficacy to the established treatment regimen with a simplified posology. The formulation provides an alternative therapy for acute bacterial conjunctivitis that should improve patient compliance and satisfaction.

Nitric oxide synthase II (NOS II) gene expression correlates with atherosclerotic intimal thickening. Preventive effects of HMG-CoA reductase inhibitors.

HMG-CoA reductase inhibitors have been shown to be effective in primary and secondary prevention of coronary heart disease. Their mechanism of action is attributed to their cholesterol lowering activity but recent results seem to indicate additional effects related to the modulation of other processes that regulate the presentation of vascular diseases. Our objective has been to study the effects of atorvastatin and simvastatin, two HMG-CoA reductase inhibitors, on lesion composition and expression of genes involved in lesion development in a diet-induced atherosclerotic rabbit model. Both HMG-CoA reductase inhibitors were administered at identical doses of 2.5 mg/kg per day with the hyperlipemic diet for 10 weeks. Both statins significantly prevented the diet-induced increase in cholesterol levels. Relative lesion composition in fibrinogen, macrophages and smooth muscle cells was unaltered by the treatment although lesion size was reduced; therefore, both HMG-CoA reductase inhibitors reduced total amounts of fibrinogen, macrophages and smooth muscle cells (simvastatin, P < 0.05). NOS II gene expression was positively and significantly correlated with lesion size and inversely correlated with HDL plasma levels. NOS II expression was markedly downregulated in simvastatin treated animals while MCP-1 was unaltered. Therefore, HMG-CoA reductase inhibition seems to interfere with atherosclerotic lesion development by reducing intimal thickening development and the expression of the cytotoxic NOS II.

Molecular characterization of a type I quantitative factor V deficiency in a thrombosis patient that is "pseudo homozygous" for activated protein C resistance.

Resistance to activated protein C (APC), which is associated with the FV Leiden mutation in the large majority of the cases, is the most common genetic risk factor for thrombosis. Several laboratory tests have been developed to detect the APC-resistance phenotype. The result of the APC-resistance test (APC-sensitivity ratio, APC-SR) usually correlates well with the FV Leiden genotype, but recently some discrepancies have been reported. Some thrombosis patients that are heterozygous for FV Leiden show an APC-SR usually found only in homozygotes for the defect. Some of those patients proved to be compound heterozygotes for the FV Leiden mutation and for a type I quantitative factor V deficiency. We have investigated a thrombosis patient characterized by an APC-SR that would predict homozygosity for FV Leiden. DNA analysis showed that he was heterozygous for the mutation. Sequencing analysis of genomic DNA revealed that the patient also is heterozygous for a G5509-->A substitution in exon 16 of the factor V gene. This mutation interferes with the correct splicing of intron 16 and leads to the presence of a null allele, which corresponds to the "non-FV Leiden" allele. The conjunction of these two defects in the patient apparently leads to the same phenotype as observed in homozygotes for the FV Leiden mutation.

The HR2 haplotype of factor V: effects on factor V levels, normalized activated protein C sensitivity ratios and the risk of venous thrombosis.

We studied the HR2 haplotype of the factor V gene in a case-control study for venous thrombosis including 474 patients with a first deep-vein thrombosis and 474 age- and sex-matched healthy controls (Leiden Thrombophilia Study, LETS). We investigated both the original His1299Arg (A4070G) polymorphism and the Met385Thr (T1328C) polymorphism. This latter polymorphism, located in exon 8 (heavy chain), is always present in the HR2 haplotype, but also occurs on its own in a His1299 (wt) background. The HR2 haplotype was not associated with an increased risk of venous thrombosis (OR = 1.2, 95% confidence interval: 0.8-2.0). We did not find an association between the HR2 haplotype and a reduced sensitivity for activated protein C (APC) in non-carriers of factor V Leiden (FVL). However, in compound heterozygous FVL/HR2 carriers the sensitivity for APC was reduced. The HR2 haplotype was also associated with reduced factor V antigen levels in both patients and controls. Sequence analysis of the promoter region of factor V in HR2 homozygotes did not reveal any sequence variations that could explain the reduced FV levels. Our results show that the HR2 haplotype is not associated with an increased risk of venous thrombosis or with a reduced sensitivity for APC in non-FVL carriers. However, the HR2 haplotype is associated with a reduced sensitivity for APC in carriers of FVL and with reduced factor V antigen levels.

Bacteriocin 28b, a chromosomally encoded bacteriocin produced by most Serratia marcescens biotypes.

Twenty-six Serratia marcescens strains belonging to fifteen different biotypes were found to produce bacteriocins active against Escherichia coli. On the basis of the pattern of bacteriocin sensitivity of E. coli mutant strains, immunological assays and Southern blot hybridization with a probe for the S. marcescens bss (bacteriocin 28b structural) gene, it was concluded that all these strains apparently produce chromosomally encoded bacteriocins related to bacteriocin 28b. To confirm this conclusion, the genes encoding the bacteriocin produced by one of these strains (S. marcescens JF246) were cloned in plasmid pBR328. E. coli harbouring recombinant plasmid pDG301 produced a bacteriocin active against E. coli and immunologically related to bacteriocin 28b. Immunoblotting experiments showed that bacteriocins 28b and L appear to have the same apparent molecular mass (45 kDa). Furthermore, recombinant plasmid pDG301 DNA hybridized with a bss gene probe.

The effect of nuclease on transformation efficiency in Serratia marcescens.

No differences in the efficiency of transformation were observed from both plasmid and chromosomal DNA in Serratia marcescens 2170 and an extracellular nuclease defective isogenic strain. The efficiency of transformation was the same for Escherichia coli 5K and E. coli containing a recombinant plasmid conferring the ability to synthesize a S. marcescens nuclease. From these results we conclude that the extracellular nuclease of S. marcescens 2170 is not the main cause of the low efficiency of transformation observed in this bacterium.

Analysis of organic sulfur compounds in wine aroma.

Sulfur-containing compounds in wines have been extensively studied because of their effect on wine aroma. The aim of this paper was to give an overview on the analytical methods developed to determine them in wines with special emphasis on gas chromatographic methods, as well as the results obtained. In addition, the problems occurring in application of the common extraction procedures, such as liquid-liquid extraction, static and dynamic headspace and solid-phase microextraction, are presented and discussed.

Solid-phase extraction applied to the determination of ochratoxin A in wines by reversed-phase high-performance liquid chromatography.

A reversed-phase high-performance liquid chromatographic method is described for the analysis of Ochratoxin A at low microg l(-1) levels in samples of artificially contaminated wines. The method involves solid-phase extraction of samples using octadecylsilane cartridges and an additional preconcentration step prior to chromatography with isocratic elution and fluorimetric detection. The method was evaluated for accuracy and precision with relative standard deviations lower than 10%. Recoveries of ochratoxin A added to commercial wines over the range 0.1-3.0 microg l(-1) were higher than 80% in the assays. The performance of the octadecylsilane cartridge method tested compared very favourably with results of other published studies of ochratoxin A which use immunoaffinity columns or solvent extraction techniques.

Chromatographic analysis of volatile sulphur compounds in wines, using the static headspace technique with flame photometric detection.

This study describes the development of a method for determining eleven sulphur compounds in wine, which takes into account that thiols are easily oxidizable. The equilibria of the analytes between air and aqueous ethanol were studied and optimised using static headspace gas chromatography in order to obtain the best sensitivities. The influences of parameters such as temperature, time, ionic strength, headspace volume and the volume of headspace injected were determined. A cryogenic trap was used to concentrate the headspace analytes and they were chromatographically analysed using GC temperature programming on a poly(ethylene glycol) capillary column with FPD detection at 394 nm. The power relationship was observed between the chromatography response and a concentration of sulphur compounds in the range 2-150 micrograms l(-1) in the sample. Recoveries were determined by the standard addition technique and were higher than 90% for sulphides and disulphides and close to 80% for thiols. The overall method was successfully used to determine the sulphur compounds in white and red wines.

Application of headspace solid-phase microextraction to the determination of sulphur compounds with low volatility in wines.

Headspace solid-phase microextraction (HS-SPME) has been used for determining sulphur compounds with low volatility in wines. With this technique, handling of samples is minimal so undesirable loses and reactions between compounds are prevented. Furthermore, this kind of extraction is fast and does not require any organic solvent. Under optimal conditions, the HS-SPME, using a new fibre coated with Stable Flex divinylbenzene-Carboxen-polydimethylsiloxane, makes possible the quantification of sixteen sulphur compounds with low volatility which may be present in wines. The limits of detection for the analytes studied ranged between 0.05 and 10 microg/l, and the recovery and repeatability found were acceptable. The method developed was successfully applied to determine the concentration of the target analytes in varietal wines from the Catalonian region (Spain) with some aromatic defects such as an odour of rubber, onion, rotten, unpleasant herbaceous, etc. The results show that the contents of the sulphur compounds studied in these wines are higher than in those without defects. This shows a relationship exists between the presence of sulphur compounds and the quality of the wine aroma.

Headspace solid-phase microextraction analysis of volatile sulphides and disulphides in wine aroma.

Sulphur compounds (S-compounds) are important constituents of wine off-flavours. Headspace solid-phase microextraction (HS-SPME) combined with gas chromatography coupled to flame photometric detection (GC-FPD) was used to develop a suitable method to analyse volatile sulphides and disulphides. This is a very simple and fast technique which gives good reproducibility at microgram/l levels (relative standard deviations < 10%). The analytes were extracted from the headspace of the samples by using either polydimethylsiloxane or polyacrylate coated fused-silica fibers in an SPME unit. Then, the fiber was inserted into the injector of a gas chromatograph and the extracted S-compounds were thermally desorbed. The influence of different parameters, such as ionic strength, stirring, headspace volume, ethanol concentration, time and temperature of extraction, was studied. The extraction of the fibers varies considerably for the different sulphur compounds studied. The most volatile compounds were the least extracted by the coating fibers tested. The standard additions technique, applied to real samples, gave the recoveries > 94%. The detection limits range between 3 micrograms/l and 50 ng/l. The overall process was successfully applied to identify and quantify S-compounds in white and red wines.

Determination of 2,4,6-trichloroanisole in wines by headspace solid-phase microextraction and gas chromatography-electron-capture detection.

One of the most important problems in the wine world, today, is cork taint, which often has been chemically identified as 2,4,6-trichloroanisole (TCA). The perception limit of this compound is very low (close to 10 and 40 ng/l for white and red wines, respectively), so, even at such low concentrations, its presence becomes a problem in wine quality. A method for the analysis of TCA in white and red wines has been developed in our laboratory, using headspace solid-phase microextraction and gas chromatography with electron-capture detection. The method, which has been optimized using an experimental design, involves the use of fibres coated with polydimethylsiloxane (PDMS) and allows the analysis of TCA at very low concentrations (under 500 ng/l) with good accuracy (RSD < or = 10%). The limits of quantification of the method are 5 and 8 ng/l for white and red wines, respectively, while the limit of detection is 1 ng/l for both types of wine.

Headspace solid-phase microextraction analysis of 3-alkyl-2-methoxypyrazines in wines.

A procedure to determine 3-alkyl-2-methoxypyrazines in wines is described. It is based on the headspace solid-phase microextraction (HS-SPME) technique after a clean-up of the sample by distillation (previously acidified to pH 0.5) to remove ethanol and other volatile compounds that can interfere in the SPME. Determination is performed by means of capillary gas chromatography using a nitrogen-phosphorus detector. The method allows quantification of 3-isobutyl-2-methoxypyrazine, 3-sec-butyl-2-methoxypyrazine and 3-isopropyl-2-methoxypyrazine at their natural concentration levels and below their sensory thresholds in Cabernet Sauvignon and Merlot wines. The method was successfully applied to experimental red wines and the evolution of their pyrazine contents during the winemaking process was monitored. Pyrazine content increased during the first maceration day but did not change significantly during alcoholic and malolactic fermentation. Final contents in wines were 12-27 ng/l of 3-isobutyl-2-methoxypyrazine and 5-10 ng/l of 3-sec-butyl-2-methoxypyrazine.

Analysis of low-volatility organic sulphur compounds in wines by solid-phase microextraction and gas chromatography.

A method for analysing low-volatility sulphur compounds using solid-phase microextraction has been developed. The analytes were extracted directly from the liquid sample using fibres coated with different stationary phases. The best extraction efficiency was obtained with Carboxen-polydimethylsiloxane coating. Ionic strength, sample volume, time and temperature of the extraction were optimised and the matrix effect studied. The method enables 15 sulphur compounds in wine to be determined at trace levels with recoveries close to 100% and limits of detection between 0.05 and 5 microg/L. The overall method was successfully applied to the determination of the sulphur compounds studied in several red, white and rosé wines.

Determination of 4-ethylguaiacol and 4-ethylphenol in red wines using headspace-solid-phase microextraction-gas chromatography.

A method for analysing 4-ethylguaiacol and 4-ethylphenol in the aroma of red wines using headspace-solid-phase microextraction is presented. The fibres used were coated with 100 microm of polydimethylsiloxane. Parameters like ionic strength, agitation of the sample, sample volume, temperature of the sample and adsorption/desorption times were studied and optimised to obtain the best extraction results. The linearity of the response was studied in the usual concentration ranges in wines (4-ethylguaiacol, 40-400 microg/l; 4-ethylphenol, 200-1800 microg/l). Repeatability of the method was determined, and the relative standard deviation was about 10%. Limits of detection and limits of quantification were also determined, and the values found were 1 and 5 microg/l for 4-ethylguaiacol and 2 and 5 microg/l for 4-ethylphenol, respectively. All these values were under the sensory thresholds established for these volatile phenols. The presence of interferences due to the matrix composition implies the use of the standard addition technique for both compounds quantification.