Obtaining reliable intraoral digital scans for an implant-supported complete-arch prosthesis: A dental technique

This article describes a technique for obtaining an accurate complete-arch digital scan for an edentulous patient. To achieve this, an auxiliary polymeric device that simulates a denture is designed, fabricated, and placed in the mouth. This device, having the geometry of a typical dental arch, facilitates the digitalization of the edentulous complete arch. This is because the change in radius of the curvature (change of geometry) enables the scanner to perform a more accurate alignment. Initially, the necessary location of the implants is acquired, and then the soft tissue is added. This technique can achieve accurate complete-arch digital scans. Distances between implants are closer to the gold standard when using this auxiliary geometry piece than those obtained without using it.     

Does a Non-Circular Chainring Improve Performance in the Bicycle Motocross Cycling Start Sprint?

Maximising power output during the initial acceleration phase of a bicycle motocross (BMX) race increases the chance to lead the group for the rest of the race. The purpose of this study was to investigate the effect of non-circular chainrings (Q-ring) on performance during the initial acceleration phase of a BMX race. Sixteen male cyclists (Spanish National BMX team) performed two counterbalanced and randomized initial sprints (3.95s), using Q- ring vs. circular chainring, on a BMX track. The sample was divided into two different groups according to their performance (Elite; n = 8 vs. Cadet; n = 8). Elite group covered a greater distance using Q-ring (+0.26 m, p = 0.02; D = 0.23), whilst the improvement for the Cadet (+0.04 m) was not significant (p = 0.87; D = -0.02). Also, there was no significant difference in power output for the Elite group, while the Cadet group revealed larger peak power with the circular chainring. Neither lactate level, nor heart rate showed significant differences due to the different chainring used. The non-circular chainring improved the initial acceleration capacity only in the Elite riders.

Key Points

• This work provides novel results demonstrating very significant improvements in the sprint performance of BMX cycling discipline using a non-circular chainring system.
• This study seeks a practical application from scientific analysis
• All data are obtained in a real context of high competition using a sample comprised by the National Spanish Team.
• Some variables influencing performance as subjects’ physical fitness are discussed.
• Technical equipment approved by International Cycling Union is studied to check its potentially beneficial influence on performance.

Key words: Power, efficiency, pedalling, biomechanics, lactate     

Allosteric properties of G protein-coupled receptor oligomers

Allosteric regulation of ligand binding is a well-established mechanism regulating the function of G protein-coupled receptors (GPCR). Allosteric modulators have been considered so far as molecules binding to an allosteric site, distinct from that of the reference ligand (orthosteric site), and able to modulate the binding affinity at the orthosteric site and/or the signaling properties resulting from orthosteric site occupancy. Given that most GPCR are known to form dimers or higher order oligomers, we explored whether allosteric interactions could also occur between protomers within oligomeric arrays, thereby influencing binding and signaling receptor properties. Two main conclusions emerged from such studies. First, allosteric modulators can affect one receptor by binding to another receptor within a dimeric or oligomeric complex. Second, allosteric modulators might act on a given receptor by targeting the "orthosteric site" in another receptor of the complex. Allosteric regulation within di(oligo)mers thus implies that the pharmacological properties of a given receptor subtype can be influenced by the array of dimerization partners coexpressed in each particular cell type. Ligands could thus act as agonists or antagonists on 1 receptor, while modulating allosterically the function of a variety of other receptors to which they do not bind directly. Allosteric regulation across GPCR oligomeric interfaces is expected to greatly influence the practice of pharmacology. It will likely affect the design of drug discovery programs, which rely mostly on the overexpression of the receptor of interest in a cell line, thereby focusing on homo-oligomers and ignoring the potential effects of other partners.     

Effects of Supplementation with Beef or Whey Protein Versus Carbohydrate in Master Triathletes

Objective: The present study compares the effect of ingesting hydrolyzed beef protein, whey protein, and carbohydrate on performance, body composition (via plethysmography), muscular thickness, and blood indices of health, including ferritin concentrations, following a 10-week intervention program.Methods: After being randomly assigned to one of the following groups—beef, whey, or carbohydrate—24 master-age (35–60 years old) male triathletes (n = 8 per treatment) ingested 20 g of supplement mixed with plain water once a day (immediately after training or before breakfast). All measurements were performed pre- and postinterventions.Results: Only beef significantly reduced body mass (p = 0.021) along with a trend to preserve or increase thigh muscle mass (34.1 ± 6.1 vs 35.5 ± 7.4 mm). Both whey (38.4 ± 3.8 vs 36.9 ± 2.8 mm) and carbohydrate (36.0 ± 4.8 vs 34.1 ± 4.4 mm) interventions demonstrated a significantly (p < 0.05) decreased vastus medialis thickness Additionally, the beef condition produced a significant (p < 0.05) increase in ferritin concentrations (117 ± 78.3 vs 150.5 ± 82.8 ng/mL). No such changes were observed for the whey (149.1 ± 92.1 vs 138.5 ± 77.7 ng/mL) and carbohydrate (149.0 ± 41.3 vs 150.0 ± 48.1 ng/mL) groups. Furthermore, ferritin changes in the beef group were higher than the modification observed in whey (p < 0.001) and carbohydrate (p = 0.025) groups. No differences were found between whey and carbohydrate conditions (p = 0.223). No further changes were observed.Conclusion: Ingesting a hydrolyzed beef protein beverage after workout or before breakfast (nontraining days) can be effective in preserving thigh muscle mass and in improving iron status in male master-age triathletes.     

An audit of paediatric dental treatments carried out under general anaesthesia in a sample of Spanish patients

OBJECTIVE: To evaluate the success and failure rates of the clinical procedures carried out under general anaesthesia in disabled or medically comprised and healthy children. BASIC RESEARCH DESIGN: Retrospective study included 47 patients who received dental treatment under general anaesthesia, grouped according to whether they were disabled or medically compromised (group A, n = 16) or not (group B, n = 31), and subgrouped according to whether they were under or over 6 years of age. RESULTS: Mean duration of anaesthesia was 2 hours and 25 minutes, with a range of 1 to 4 hours. The percentage of children followed up was 87%. The procedures performed were: 105 preformed metal crowns, 142 restorations, 85 pulpotomies and 166 extractions. The success rate was 93% for preformed metal crowns, 96% for pulpotomies and 90% for restorations. CONCLUSIONS: General anaesthesia is necessary in some children, but should be complemented with a preventive programme, behavioural remodelling and a follow-up schedule to avoid having to repeat the use of general anaesthesia.     

Loudness and auditory steady-state responses in normal-hearing subjects

This study evaluated the use of multiple auditory steady-state responses (ASSRs) to estimate the growth of loudness in listeners with normal hearing. Individual intensity functions were obtained from measures of loudness growth using the contour test and from the electrophysiological amplitude measures of multiple amplitude-modulated (77–105Hz) tones (500, 1000, 2000, and 4000Hz) simultaneously presented to both ears and recorded over the scalp. Slope analyses for the behavioural and electrophysiological intensity functions were separately performed. Response amplitudes of the ASSRs and loudness sensation judgements increase as the stimulus intensity increases for the four frequencies studied. A significant relationship was obtained between loudness and the ASSRs. The results of this study suggest that the amplitude of the ASSRs may be used to estimate loudness growth at least for individuals with normal hearing.     

Comparison of the Cozart DDS 801 on-site drug test device and gas chromatography/mass spectrometry (GC/MS) confirmation results of cannabis and cocaine in oral fluid specimens

Driving under the influence of drugs (DUID) is a problem around the world. The objective of this study is to assess the reliability of the oral fluid screening device the Cozart DDS 801 by comparing the on-site results with confirmatory gas chromatography/mass spectrometry (GC/MS) oral fluid analysis. The study was carried out in Catalonia (Spain) with a sample of 2180 oral fluid specimens taken from subjects suspected of driving under the influence of drugs of abuse, and collected by police officers during 2009–2010. Statistical parameters of the tests were determined for cannabis and cocaine. The sensitivity, specificity, predictive positive value, predictive negative value, likelihood positive ratio and likelihood negative ratio for cocaine were 92%, 90%, 95%, 85%, 9.44, and 0.09 respectively. Sensitivity, specificity, predictive positive value, predictive negative value, likelihood positive ratio and likelihood negative ratio for cannabis were 87%, 86%, 94%, 73%, 6.15 and 0.6 respectively. Accuracy was 91% for cocaine and 86% for cannabis. The Cozart DDS 801 drug test system is a simple to use screening tool for cocaine and cannabis in oral fluid, at initial screening cut-off established by the manufacturer, confirmed with a GC/MS analysis. The system has demonstrated its acceptable performance.