Cassava starch biodegradable films: Influence of glycerol and clay nanoparticles content on tensile and barrier properties and glass transition temperature

In this this study, glycerol content and its incorporation method on tensile and barrier properties of biodegradable films (BF) based on cassava starch were analyzed. ANOVA showed that the glycerol incorporation method did not influence the results (P > 0.05), however the glycerol content influenced significantly the tensile and barrier properties of the films (P < 0.05). Films prepared with lower glycerol content presented better tensile and barrier properties than films with higher content. Films were then prepared with addition of clay nanoparticles and their tensile and barrier properties and glass transition temperature were measured. ANOVA indicated that both glycerol and clay nanoparticles influenced significantly the tensile and barrier properties (P < 0.05), diminishing film permeability when clay nanoparticles were present, while the glass transition temperature was not influenced (P > 0.05). (C) 2011 Elsevier Ltd. All rights reserved.

Efeito de diferentes gomas de mascar sobre o pH salivar de crianças

Objective: To evaluate the effect of different chewing gum brands on the salivary pH of children with primary dentition. Method: Forty children were selected and assigned to four groups: control (no chewing gum); sugarless chewing gum; chewing gum with casein phosphopeptide-amorphous calcium phosphate; and chewing gum with xylitol. The first saliva collection was made after supervised tooth brushing for stabilization of the oral pH. Next, all children were instructed to drink slowly 100 mL of a cola-based soft drink (Coca-Cola®) and a new saliva collection was made 10 min later. Then, each group chewed on the chewing gum for 5 min and discarded it after this time. Saliva was collected again at 5, 10 and 15 min intervals after start using the chewing gum. Measurement of salivary pH was made with colorimetric test papers and a digital pH-meter. Data were analyzed statistically by analysis of variance and Tukey’s test at a 5% significance level. Results: The use of chewing gums accelerated the increase of salivary pH to considerably alkaline levels after consumption of an acidic beverage, especially within the first minutes. The highest levels were obtained in the groups of children that used chewing gums containing xylitol and casein phosphopeptide-amorphous calcium phosphate. Conclusion: Children that used the chewing gums after ingestion of an acidic soft drink presented an increase in salivary pH, with the best results in the groups that used chewing gums containing casein phosphopeptide-amorphous calcium phosphate and xylitol.

The uncertainty in standardised sound power measurements: complying with ISO 17025

In the context of “testing laboratory” one of the most important aspect to deal with is the measurement result. Whenever decisions are based on measurement results, it is important to have some indication of the quality of the results. In every area concerning with noise measurement many standards are available but without an expression of uncertainty, it is impossible to judge whether two results are in compliance or not. ISO/IEC 17025 is an international standard related with the competence of calibration and testing laboratories. It contains the requirements that testing and calibration laboratories have to meet if they wish to demonstrate that they operate to a quality system, are technically competent and are able to generate technically valid results. ISO/IEC 17025 deals specifically with the requirements for the competence of laboratories performing testing and calibration and for the reporting of the results, which may or may not contain opinions and interpretations of the results. The standard requires appropriate methods of analysis to be used for estimating uncertainty of measurement. In this point of view, for a testing laboratory performing sound power measurement according to specific ISO standards and European Directives, the measurement of uncertainties is the most important factor to deal with. Sound power level measurement, according to ISO 3744:1994 , performed with a limited number of microphones distributed over a surface enveloping a source is affected by a certain systematic error and a related standard deviation. Making a comparison of measurement carried out with different microphone arrays is difficult because results are affected by systematic errors and standard deviation that are peculiarities of the number of microphones disposed on the surface, their spatial position and the complexity of the sound field. A statistical approach could give an overview of the difference between sound power level evaluated with different microphone arrays and an evaluation of errors that afflict this kind of measurement. Despite the classical approach that tend to follow the ISO GUM this thesis present a different point of view of the problem related to the comparison of result obtained from different microphone arrays.

Funzionalizzazione della mandibola dopo ricostruzione con lembo libero rivascolarizzato di fibula "single strut". Al di là del deficit di verticalità.

Obiettivi: Valutare la modalità  più efficace per la riabilitazione funzionale del limbo libero di fibula "single strut", dopo ampie resezioni per patologia neoplastica maligna del cavo orale. Metodi: Da una casistica di 62 ricostruzioni microvascolari con limbo libero di fibula, 11 casi sono stati selezionati per essere riabilitati mediante protesi dentale a supporto implantare. 6 casi sono stati trattati senza ulteriori procedure chirurgiche ad eccezione dell'implantologia (gruppo 1), affrontando il deficit di verticalità  della fibula attraverso la protesi dentaria, mentre i restanti casi sono stati trattati con la distrazione osteogenetica (DO) della fibula prima della riabilitazione protesica (gruppo 2). Il deficit di verticalità  fibula/mandibola è stato misurato. I criteri di valutazione utilizzati includono la misurazione clinica e radiografica del livello osseo e dei tessuti molli peri-implantari, ed il livello di soddisfazione del paziente attraverso un questionario appositamente redatto. Risultati: Tutte le riabilitazioni protesiche sono costituite da protesi dentali avvitate su impianti. L'età  media è di 52 anni, il rapporto uomini/donne è di 6/5. Il numero medio di impianti inseriti nelle fibule è di 5. Il periodo massimo di follow-up dopo il carico masticatorio è stato di 30 mesi per il gruppo 1 e di 38.5 mesi (17-81) di media per il gruppo 2. Non abbiamo riportato complicazioni chirurgiche. Nessun impianto è stato rimosso dai pazienti del gruppo 1, la perdita media di osso peri-implantare registrata è stata di 1,5 mm. Nel gruppo 2 sono stati riportati un caso di tipping linguale del vettore di distrazione durante la fase di consolidazione e un caso di frattura della corticale basale in assenza di formazione di nuovo osso. L'incremento medio di osso in verticalità è stato di 13,6 mm (12-15). 4 impianti su 32 (12.5%) sono andati persi dopo il periodo di follow-up. Il riassorbimento medio peri-implantare, è stato di 2,5 mm. Conclusioni: Le soluzioni più utilizzate per superare il deficit di verticalità  del limbo libero di fibula consistono nell'allestimento del lembo libero di cresta iliaca, nel posizionare la fibula in posizione ideale da un punto di vista protesico a discapito del profilo osseo basale, l'utilizzo del lembo di fibula nella versione descritta come "double barrel", nella distrazione osteogenetica della fibula. La nostra esperienza concerne il lembo libero di fibula che nella patologia neoplastica maligna utilizziamo nella versione "single strut", per mantenere disponibili tutte le potenzialità  di lunghezza del peduncolo vascolare, senza necessità  di innesti di vena. Entrambe le soluzioni, la protesi dentale ortopedica e la distrazione osteogenetica seguita da protesi, entrambe avvitate su impianti, costituiscono soluzioni soddisfacenti per la riabilitazione funzionale della fibula al di là  del suo deficit di verticalità . La prima soluzione ha preso spunto dall'osservazione dei buoni risultati della protesi dentale su impianti corti, avendo un paragonabile rapporto corona/radice, la DO applicata alla fibula, sebbene sia risultata una metodica con un numero di complicazioni più elevato ed un maggior livello di riassorbimento di osso peri-implantare, costituisce in ogni caso una valida opzione riabilitativa, specialmente in caso di notevole discrepanza mandibulo/fibulare. Decisiva è la scelta del percorso terapeutico dopo una accurata valutazione di ogni singolo caso. Vengono illustrati i criteri di selezione provenienti dalla nostra esperienza.

Beschleunigte postoperative Rekonvaleszenz bei Coloneingriffen durch Kaugummikauen und Periduralkatheter

Ein wesentliches Problem der elektiven Colonchirurgie ist die postoperative Darmträgheit. Sie wird von verschieden Faktoren wie der Manipulation am Darm, Ausschüttung von inflamatorischen Substanzen und durch perioperativ notwendige Medikamente wie morphinhaltige Analgetika ausgelöst und aufrechterhalten. Sie führt zu körperlichem Unwohlsein, einem geblähten Abdomen und gegebenenfalls zu Schmerzen. Die Patienten leiden unter Übelkeit und Erbrechen, fühlen sich müde, abgeschlagen und haben einen höheren Schmerzmittelverbrauch. Hierdurch wird die Motivation zur Mobilisation herabgesetzt und führt zu längerem Aufenthalt im Krankenbett, wodurch wiederum die Darmträgheit gefördert, die Rekonvaleszenz verlängert und die Patientenzufriedenheit gemindert wird. Eine längere Immobilisation steigert die Komplikationshäufigkeit, vor allem für thrombo-embolische Ereignisse.rnrnDurch die Einführung des Periduralkatheters (PDK) und der laparoskopischen Operationstechnik in die Colonchirurgie sind die Voraussetzungen zur Frühmobilisation verbessert worden.rnDeshalb und durch den wachsenden wirtschaftlichen Druck zu kürzeren Rekonvaleszenzzeiten und zur Optimierung der Bettenauslastung, sind in den letzten Jahren eine Vielzahl von Konzepten zur beschleunigten postoperativen Rekonvaleszenz erarbeitet worden, die unter dem Schlagwort „Fast Track“ bekannt geworden sind.rnWesentliche Punkte sind hierbei die längst mögliche Erhaltung des körpereigenen Gleichgewichts durch Verzicht auf Darmsäuberung und längere präoperative Nüchternheit. Intraoperativ werden flüssigkeitsrestriktive Infusionsschemata genutzt und auf eine Minimierung der intravenösen Dosierung von morphinhaltigen Analgetika geachtet. Postoperativ gehören die Frühmobilisation sowie die „Frühenterale –Ernährung“ zu den wichtigsten Merkmalen.rnDie Implementierung eines solchen Konzeptes als Standard in den laufenden Betrieb ist sehr aufwendig und teuer. Die individuelle Verträglichkeit der „Frühenteralen – Ernährung“ ist sehr unterschiedlich und wird oft von den Patienten aufgrund der postoperativen Darmträgheit nicht gut toleriert.rnrnEin neuer Ansatz hierfür ist das sogenannte „sham feeding“, also das Vortäuschen von Nahrungsaufnahme durch Kaugummikauen, das helfen soll die Paralyse des Darms postoperativ schneller, komplikationsärmer, sicherer und kostengünstiger zu beheben.rnrnZiel der vorliegenden Studie war es, die Effekte von Kaugummikauen sowie der Kombination von Kaugummikauen und Verwendung eines PDK in Hinblick auf postoperative Rekonvaleszenz, Darmtätigkeit und Patientenzufriedenheit bei unseren Patienten zu vergleichen, um einen Benefit des „sham feedings“ aufzuzeigen. Gleichzeitig sollten alle Einflußgrößen wie Mobilisation, Kostverträglichkeit, Schmerzmittelbedarf und Komplikationen mit erfasst werden, um die jeweilige Effektivität jeweils besser beurteilen zu können.rnDie vorliegende Arbeit soll die Frage beantworten, ob Patienten mit colonresizierenden Eingriffen postoperativ von „sham feeding“ durch kaugummikauen profitieren und ob dies standardmäßig genutzt werden sollte.rn

Investigation of different shellac grades and improvement of release from air suspension coated pellets

Shellac is the purified product of the natural polymer Lac. Shellac types, from different origins and with different ages, all purified by the solvent extraction process were compared in this study. Their physicochemical properties acid value, glass transition temperatures, color numbers and molecular sizes were determined. Metoprolol tartrate pellets were coated by air suspension coating with these different grades of shellac. Two coating levels 20% w/w and 25% w/w were applied and then subjected to in vitro dissolution testing. Enteric resistance was achieved for all tested brands for the two coating levels. At pH 6.8, 7.2 and 7.4, significant variations were obvious between the brands. rnMoreover the molecular size of shellac has a pronounced effect in that shellac types with larger molecular size show a higher and faster release than others, while the one with the smaller molecular size show the opposite effect on the release of metoprolol.rnIn this study commercially available ready for use aqueous shellac solutions (SSB AQUAGOLD), which are based on shellac SSB 57 (Dewaxed Orange Shellac, Bysakhi-Ber type refined in a solvent extraction process), with different manufacturing dates were used. rnTo improve the enteric coating properties of films from aqueous shellac solutions, different aqueous polymeric solutions of hydroxypropyl methylcellulose (HPMC), hydroxypropyl cellulose (HPC), carboyxmethyl cellulose (CMC), gum arabic and polysaccharides (Pullulan®) were used. These water soluble polymers will act as pore formers to enhance drug release from pellets coated with the combination of shellac and these polymers. The influence of these polymers on the gloss of the shellac films, mechanical properties of the films and drug release from metoprolol tartrate pellets were studied.rnThe potential of ethanol to alter the rate of drug release from shellac coated pellets was assessed by using a modified in vitro dose dumping in alcohol (DDA) method and the test concluded that shellac coated dosage forms can be co-administered with alcohol beverages containing ≤ 5% with no effect of alcohol on the shellac coat.rnPellets coated with shellac sodium salts, showed higher release rates than pellets coated with shellac as ammonium salt forms. rn

Proposta di sottotitolazione in italiano del film "Я шагаю по Москве" (1963)

Il tema del mio elaborato finale è la sottotitolazione del film “A passeggio per Mosca” di Georgij Danelija (1963), un noto regista russo. I suoi film più famosi sono “Мимино” (Mimino) e “Осенный марафон” (“Maratona d’autunno”). L’attore protagonista del film è Nikita Michalkov, famoso attore e regista, nonché personaggio controverso della vita culturale russa; il suo film più famoso è “Утомлённые солнцем” (“Sole ingannatore”). I personaggi più anziani furono interpretati da attori famosi quali Rolan Bykov, attore di teatro, e Vladimir Basov, regista e attore straordinariamente versatile. I ruoli principali, invece, furono affidati ad attori meno noti: Aleksej Loktev e Evgenij Steblov, che si dedicarono entrambi al teatro per gran parte della propria vita, e Galina Pol’skich, che divenne una grande attrice di film drammatici. Straordinari sono anche il lavoro dell’operatore cinematografico Vadim Jusov e quello del compositore Andrej Petrov. Il film suscitò diverse impressioni nel pubblico e nella critica e fu accolto positivamente da Chruščёv: presto sarebbe diventato un simbolo del “Disgelo”, un periodo in cui Chruščёv effettuò un’opera di destalinizzazione dell’URSS: il clima era quindi più disteso, sebbene vi fosse un malcontento diffuso a causa dell’economia fallimentare dello Stato. La canzone finale, che contribuì al successo del film, esprime perfettamente quest’atmosfera spensierata, che pervade anche Mosca, la vera protagonista del film. Della capitale vengono inquadrati i luoghi più importanti: tra questi il parco Gorkij, la metropolitana e il GUM. Tradurre i sottotitoli del film non è stato facile. In particolare, ho incontrato difficoltà nel tradurre alcune particelle russe che non hanno un equivalente in italiano e battute in cui erano presenti importanti riferimenti culturali. Il lavoro a cui mi sono dedicata con più impegno è stato la traduzione della canzone finale: desideravo che i sottotitoli italiani fossero in rima e conservassero il significato dei versi originari.

Comparing expectations and experiences of care for sexually transmitted infections in general practice: a qualitative study

Background A key aim of England's National Strategy for Sexual Health is to extend high-quality sexual health services in primary care. Objectives To explore the expectations and experiences of men and women who initially presented at their general practice with a suspected sexually transmitted infection in order to identify areas where change could improve service delivery. Methods Semi-structured interviews were carried out in six general practices and two genitourinary medicine (GUM) clinics in Brent primary care trust (London) and Bristol (southwest England). Patients within general practice, and GUM patients who had initially attended general practice were eligible to participate. Interview transcripts were analysed using thematic analysis. Results 49 patients (29 women, 20 men) were interviewed. Patients approaching their GP practice typically expected written referral or in-house care, but this expectation was often not met. Absence of formal referral, lack of information and perceived avoidance of sexual health matters by practitioners were commonly cited as reasons for disappointment. However, a dedicated service within general practice met expectations well. Conclusion Purchasers and providers of all general practice services should ensure that any patient consulting in primary care with a suspected sexually transmitted infection can either receive appropriate care there, or a formal and supported referral to a specialised GUM clinic or primary care service.

Testing for sexually transmitted infections in general practice: cross-sectional study

Background Primary care is an important provider of sexual health care in England. We sought to explore the extent of testing for chlamydia and HIV in general practice and its relation to associated measures of sexual health in two contrasting geographical settings. Methods We analysed chlamydia and HIV testing data from 64 general practices and one genitourinary medicine (GUM) clinic in Brent (from mid-2003 to mid-2006) and 143 general practices and two GUM clinics in Avon (2004). We examined associations between practice testing status, practice characteristics and hypothesised markers of population need (area level teenage conception rates and Index of Multiple Deprivation, IMD scores). Results No HIV or chlamydia testing was done in 19% (12/64) of general practices in Brent, compared to 2.1% (3/143) in Avon. In Brent, the mean age of general practitioners (GPs) in Brent practices that tested for chlamydia or HIV was lower than in those that had not conducted testing. Practices where no HIV testing was done had slightly higher local teenage conception rates (median 23.5 vs. 17.4/1000 women aged 15-44, p = 0.07) and served more deprived areas (median IMD score 27.1 vs. 21.8, p = 0.05). Mean yearly chlamydia and HIV testing rates, in practices that did test were 33.2 and 0.6 (per 1000 patients aged 15-44 years) in Brent, and 34.1 and 10.3 in Avon, respectively. In Brent practices only 20% of chlamydia tests were conducted in patients aged under 25 years, compared with 39% in Avon. Conclusions There are substantial geographical differences in the intensity of chlamydia and HIV testing in general practice. Interventions to facilitate sexually transmitted infection and HIV testing in general practice are needed to improve access to effective sexual health care. The use of routinely-collected laboratory, practice-level and demographic data for monitoring sexual health service provision and informing service planning should be more widely evaluated.

Variation in partner notification outcomes for chlamydia in UK genitourinary medicine clinics: multilevel study

Objectives To compare different ways of measuring partner notification (PN) outcomes with published audit standards, examine variability between clinics and examine factors contributing to variation in PN outcomes in genitourinary medicine (GUM) clinics in the UK. Methods Reanalysis of the 2007 BASHH national chlamydia audit. The primary outcome was the number of partners per index case tested for chlamydia, as verified by a healthcare worker or, if missing, reported by the patient. Control charts were used to examine variation between clinics considering missing values as zero or excluding missing values. Hierarchical logistic regression was used to investigate factors contributing to variation in outcomes. Results Data from 4616 individuals in 169 genitourinary medicine clinics were analysed. There was no information about the primary outcome in 41% of records. The mean number of partners tested for chlamydia ranged from 0 to 1.5 per index case per clinic. The median across all clinics was 0.47 when missing values were assumed to be zero and 0.92 per index case when missing values were excluded. Men who have sex with men were less likely than heterosexual men and patients with symptoms (4-week look-back period) were less likely than asymptomatic patients (6-month look-back) to report having one or more partners tested for chlamydia. There was no association between the primary outcome and the type of the health professional giving the PN advice. Conclusions The completeness of PN outcomes recorded in clinical notes needs to improve. Further research is needed to identify auditable measures that are associated with successful PN that prevents repeated chlamydia in index cases.

What can be gained from comprehensive disaggregate surveillance? The Avon Surveillance System for Sexually Transmitted Infections

OBJECTIVE: To describe a new disaggregate surveillance system covering key diagnosed sexually transmitted infections in a UK locality. METHODS: The Avon System for Surveillance of Sexually Transmitted Infections (ASSIST) collects computerised person- and episode-based information about laboratory-diagnosed sexually transmitted infections from genitourinary medicine (GUM) clinics, the Avon Brook Clinic, and the Health Protection Agency and trust laboratories in primary care trusts in Avon. The features of the system are illustrated here, by describing chlamydia-testing patterns according to the source of test, age and sex, and by mapping the distribution of chlamydia across Bristol, UK. RESULTS: Between 2000 and 2004, there were 821,685 records of tests for sexually transmitted infections, with 23,542 positive results. The proportion of tests and positive results for chlamydia and gonorrhoea sent from general practice increased over time. Most chlamydia tests in both GUM and non-specialist settings were performed on women aged >25 years, but positivity rates were highest in women aged <25 years. The positivity rate remained stable between 2000 and 2004. Including data from all diagnostic settings, chlamydia rates were about twice as high as those estimated only from genitourinary clinic cases. CONCLUSIONS: The ASSIST model could be a promising new tool for planning and measuring sexual health services in England if it can become sustainable and provide more timely data using fewer resources. Collecting denominator data and including infections diagnosed in primary care are essential for meaningful surveillance.

Perioperative use of crystalloids in patients undergoing open radical cystectomy: balanced Ringer's maleate versus a glucose 5%/potassium-based balanced solution: study protocol for a randomized controlled trial

BACKGROUND The optimal crystalloid solution to use perioperatively in patients undergoing open radical cystectomy remains unclear. Many of the fluids used for intravenous hydration contain supraphysiologic concentrations of chloride, which can induce hyperchloremia and metabolic acidosis, resulting in renal vasoconstriction and decreased renal function. In addition, patients receiving less fluid and less sodium show faster recovery of gastrointestinal (GI) function after colonic surgery. METHODS AND DESIGN This is an investigator-initiated, single-center, randomized, controlled, parallel group trial with assessor-blinded outcome assessment, in the Department of Urology, University Hospital Bern, Switzerland. The study will involve 44 patients with bladder cancer scheduled for radical cystectomy and urinary diversion. The primary outcome is the duration between the end of surgery and the return of the GI function (first defecation). Secondary outcomes are fluid balance (body weight difference postoperatively versus preoperatively) and the incidence of kidney function disorders according to the Risk-Injury-Failure-Loss-End Stage Renal Disease (RIFLE classification). An equal number of patients are allocated to receive Ringerfundin® solution or a glucose/potassium-based balanced crystalloid solution as baseline infusion during the entire time that intravenous administration of fluid is necessary during the perioperative period. The randomized crystalloid solution is infused at a rate of 1 ml/kg/h until the bladder has been removed, followed by 3 ml/kg/h until the end of surgery. Postoperative hydration is identical in both groups and consists of 1,500 ml of the randomized crystalloid solution per 24 hours. Postoperative patient care is identical in both groups; patients are allowed to drink clear fluids immediately after surgery, and liquid diet is started on postoperative day 1, as well as active mobilization and the use of chewing gum. Body weight is measured daily in the morning. Time of first flatus and first defecation are recorded. DISCUSSION This trial assesses the benefits and harms of two different balanced crystalloid solutions for perioperative fluid management in patients undergoing open radical cystectomy with urinary diversion, with regard to return of GI function and effects on postoperative renal function. TRIAL REGISTRATION Current Controlled Trials ISRCTN32976792 (registered on November 21 2013).

Enhanced Recovery after Urological Surgery: A Contemporary Systematic Review of Outcomes, Key Elements, and Research Needs

CONTEXT Enhanced Recovery after Surgery (ERAS) programs are multimodal care pathways that aim to decrease intra-operative blood loss, decrease postoperative complications, and reduce recovery times. OBJECTIVE To overview the use and key elements of ERAS pathways, and define needs for future clinical trials. EVIDENCE ACQUISITION A comprehensive systematic MEDLINE search was performed for English language reports published before May 2015 using the terms "postoperative period," "postoperative care," "enhanced recovery after surgery," "enhanced recovery," "accelerated recovery," "fast track recovery," "recovery program," "recovery pathway", "ERAS," and "urology" or "cystectomy" or "urologic surgery." EVIDENCE SYNTHESIS We identified 18 eligible articles. Patient counseling, physical conditioning, avoiding excessive alcohol and smoking, and good nutrition appeared to protect against postoperative complications. Fasting from solid food for only 6h and perioperative liquid-carbohydrate loading up to 2h prior to surgery appeared to be safe and reduced recovery times. Restricted, balanced, and goal-directed fluid replacement is effective when individualized, depending on patient morbidity and surgical procedure. Decreased intraoperative blood loss may be achieved by several measures. Deep vein thrombosis prophylaxis, antibiotic prophylaxis, and thermoregulation were found to help reduce postsurgical complications, as was a multimodal approach to postoperative nausea, vomiting, and analgesia. Chewing gum, prokinetic agents, oral laxatives, and an early resumption to normal diet appear to aid faster return to normal bowel function. Further studies should compare anesthetic protocols, refine analgesia, and evaluate the importance of robot-assisted surgery and the need/timing for drains and catheters. CONCLUSIONS ERAS regimens are multidisciplinary, multimodal pathways that optimize postoperative recovery. PATIENT SUMMARY This review provides an overview of the use and key elements of Enhanced Recovery after Surgery programs, which are multimodal, multidisciplinary care pathways that aim to optimize postoperative recovery. Additional conclusions include identifying effective procedures within Enhanced Recovery after Surgery programs and defining needs for future clinical trials.

A novel colourimetric technique to assess chewing function using two-coloured specimens: Validation and application

OBJECTIVES Chewing efficiency may be evaluated using cohesive specimen, especially in elderly or dysphagic patients. The aim of this study was to evaluate three two-coloured chewing gums for a colour-mixing ability test and to validate a new purpose built software (ViewGum©). METHODS Dentate participants (dentate-group) and edentulous patients with mandibular two-implant overdentures (IOD-group) were recruited. First, the dentate-group chewed three different types of two-coloured gum (gum1-gum3) for 5, 10, 20, 30 and 50 chewing cycles. Subsequently the number of chewing cycles with the highest intra- and inter-rater agreement was determined visually by applying a scale (SA) and opto-electronically (ViewGum©, Bland-Altman analysis). The ViewGum© software determines semi-automatically the variance of hue (VOH); inadequate mixing presents with larger VOH than complete mixing. Secondly, the dentate-group and the IOD-group were compared. RESULTS The dentate-group comprised 20 participants (10 female, 30.3±6.7 years); the IOD-group 15 participants (10 female, 74.6±8.3 years). Intra-rater and inter-rater agreement (SA) was very high at 20 chewing cycles (95.00-98.75%). Gums 1-3 showed different colour-mixing characteristics as a function of chewing cycles, gum1 showed a logarithmic association; gum2 and gum3 demonstrated more linear behaviours. However, the number of chewing cycles could be predicted in all specimens from VOH (all p<0.0001, mixed linear regression models). Both analyses proved discriminative to the dental state. CONCLUSION ViewGum© proved to be a reliable and discriminative tool to opto-electronically assess chewing efficiency, given an elastic specimen is chewed for 20 cycles and could be recommended for the evaluation of chewing efficiency in a clinical and research setting. CLINICAL SIGNIFICANCE Chewing is a complex function of the oro-facial structures and the central nervous system. The application of the proposed assessments of the chewing function in geriatrics or special care dentistry could help visualising oro-functional or dental comorbidities in dysphagic patients or those suffering from protein-energy malnutrition.

NADPH-CYTOCHROME P-450 REDUCTASE: EVIDENCE FOR TWO SEPARATE STRUCTURAL DOMAINS AND ISOLATION AND CHARACTERIZATION OF THE MEMBRANE ASSOCIATED SEGMENT

Homogenous detergent-solubilized NADPH-Cytochrome P-450 reductase was incorporated into microsomes and liposomes. This binding occurred spontaneously at temperatures between 4(DEGREES) and 37(DEGREES) and appeared to involve hydrophobic forces as the binding was not disrupted by 0.5 M sodium chloride. This exogenously-added reductase was active catalytically towards native cytochrome P-450, suggesting an association with the microsomal membrane similar to endogenous reductase. Homogeneous detergent-solubilized reductase was disaggregated by Renex-690 micelles, confirming the presence of a hydrophobic combining region on the enzyme. In contrast to these results, steapsin protease-solubilized reductase was incapable of microsomal attachment and did not interact with Renex-690 micelles. Detergent-solubilized reductase (76,500 daltons) was converted into a form with the electrophoretic mobility of steapsin protease-solubilized reductase (68,000 daltons) and a 12,500 dalton peptide (as determined by polyacrylamide-SDS gel electrophoresis) when the liposomal-incorporated enzyme was incubated with steapsin protease. The 68,000 dalton fragment thus obtained had properties identical with steapsin protease-solubilized reductase, i.e. it was catalytically active towards cytochrome c but inactive towards cytochrome P-450 and did not bind liposomes. The 12,500 dalton fragment remained associated with the liposomes when the digest was fractionated by gel filtration, suggesting that this is the segment of the enzyme which is embedded in the phospholipid bilayer. Thus, detergent-solubilized reductase appears to contain a soluble catalytic domain and a separate and separable membrane-binding domain. This latter domain is required for attaching the enzyme to the membrane and also to facilitate the catalytic interaction between the reductase and its native electron acceptor, cytochrome P-450. The membrane-binding segment of the reductase was isolated by preparative gel electrophoresis in SDS following its generation by proteolytic treatment of liposome-incorporated reductase. The peptide has a molecular weight of 6,400 as determined by gel filtration in 8 M guanidine hydrochloride and has an amino acid composition which is not especially hydrophobic. Following removal of SDS and dialysis out of 6 M urea, the membrane-binding peptide was unable to inhibit the activity of a reconstituted system containing purified reductase and cytochrome P-450. Moreover, when reductase and cytochrome P-450 were added to liposomes which contained the membrane-binding peptide, it was determined that mixed function oxidase activity was reconstituted as effectively as when vesicles without the membrane-binding peptide were used. Thus, the membrane-binding peptide was ineffective as an inhibitor of mixed function oxidase activity, suggesting perhaps that it facilitates catalysis by anchoring the catalytic domain of the reductase proximal to cytochrome P-450 (i.e. in the same mixed micelle) rather than through a specific interaction with cytochrome P-450. ^