Structural modifications of the salivary conditioning film upon exposure to sodium bicarbonate: implications for oral lubrication and mouthfeel.

The salivary conditioning film (SCF) that forms on all surfaces in the mouth plays a key role in lubricating the oral cavity. As this film acts as an interface between tongue, enamel and oral mucosa, it is likely that any perturbations to its structure could potentially lead to a change in mouthfeel perception. This is often experienced after exposure to oral hygiene products. For example, consumers that use dentifrice that contain a high concentration of sodium bicarbonate (SB) often report a clean mouth feel after use; an attribute that is clearly desirable for oral hygiene products. However, the mechanisms by which SB interacts with the SCF to alter lubrication in the mouth is unknown. Therefore, saliva and the SCF was exposed to high ionic strength and alkaline solutions to elucidate whether the interactions observed were a direct result of SB, its high alkalinity or its ionic strength. Characteristics including bulk viscosity of saliva and the viscoelasticity of the interfacial salivary films that form at both the air/saliva and hydroxyapatite/saliva interfaces were tested. It was hypothesised that SB interacts with the SCF in two ways. Firstly, the ionic strength of SB shields electrostatic charges of salivary proteins, thus preventing protein crosslinking within the film and secondly; the alkaline pH (≈8.3) of SB reduces the gel-like structure of mucins present in the pellicle by disrupting disulphide bridging of the mucins via the ionization of their cysteine's thiol group, which has an isoelectric point of ≈8.3.

Stability of Evolving Multiagent Systems.

A multiagent system is a distributed system where the agents or nodes perform complex functions that cannot be written down in analytic form. Multiagent systems are highly connected, and the information they contain is mostly stored in the connections. When agents update their state, they take into account the state of the other agents, and they have access to those states via the connections. There is also external user-generated input into the multiagent system. As so much information is stored in the connections, agents are often memory less. This memory-less property, together with the randomness of the external input, has allowed us to model multiagent systems using Markov chains. In this paper, we look at multiagent systems that evolve, i.e., the number of agents varies according to the fitness of the individual agents. We extend our Markov chain model and define stability. This is the start of a methodology to control multiagent systems. We then build upon this to construct an entropy-based definition for the degree of instability (entropy of the limit probabilities), which we used to perform a stability analysis. We then investigated the stability of evolving agent populations through simulation and show that the results are consistent with the original definition of stability in nonevolving multiagent systems, proposed by Chli and De Wilde. This paper forms the theoretical basis for the construction of digital business ecosystems, and applications have been reported elsewhere.

[Prehospital airway management of laryngeal tubes. Should the laryngeal tube S with gastric drain tube be preferred in emergency medicine?]. / Präklinische Anwendung des Larynxtubus. Bietet der Larynxtubus S mit Magensonde Vorteile in der Notfallmedizin?

Laryngeal tubes (LT) are increasingly being used for emergency airway management. This article reports on two patients in whom out-of-hospital intubation with a single-lumen LT was associated with massive pulmonary aspiration in one patient and gastric overinflation in the other. In both cases peak inspiratory pressures exceeded the LT leak pressure of approximately 35 mbar. This resulted in gastric inflation and decreased pulmonary compliance and increased inspiratory pressure further, thereby creating a vicious circle. It is therefore recommended that laryngeal tube suction (LTS) should be used in all cases of emergency airway management and a gastric drain tube be inserted through the dedicated second lumen. Apart from gastric overinflation, incorrect LT/LTS placement must be detected and immediately corrected, e.g. in cases of difficult or impossible gastric tube placement, permanent drainage of air from the gastric tube, decreasing minute ventilation or an ascending capnography curve.

Molecular marker assisted broadening of the Central European heterotic groups in rye with Eastern European germplasm.

Broadening the genetic base of heterotic pools is a key to ensure continued genetic gains in hybrid breeding and extend hybrid cultivation to new areas. In the present study, two Central European heterotic pools (Carsten and Petkus) and five Eastern European open-pollinated varieties (OPVs, Pop-1 to Pop-5) were studied with the objectives to (1) investigate the genetic diversity in OPVs and the heterotic pools using molecular and field data, (2) evaluate the molecular diversity among OPVs, (3) examine the combining ability for grain yield of the OPVs when crossed with testers in field trials, and (4) develop a strategy for targeted introgression of OPV germplasm into the heterotic pools. In total, 610 S(0) plants, 347 from OPVs and 263 from heterotic pools, were developed. Clones of the S(0) plants of OPVs were crossed with two testers belonging to each heterotic pool, while clones of heterotic pools were crossed with only the opposite tester. Testcrosses were evaluated for grain yield in multi-location trials. In addition, 589 S(0) plants were fingerprinted with 30 SSR markers. The data revealed that the Carsten pool has a narrow genetic base and should be the primary target for broadening the established heterotic pattern. Mean and genetic variance suggested that Pop-2 and Pop-4 are good candidates for introgression in Petkus pool and Pop-5 in Carsten pool. Nevertheless, introgression of Pop-5 in Carsten could reduce the genetic diversity between heterotic pools. Therefore, we suggest that either selected plants of Pop-5 should be introgressed or more Eastern European germplasm should be fingerprinted and field evaluated to identify promising germplasm for broadening the established heterotic pattern.

Testcross performance of rye introgression lines developed by marker-assisted backcrossing using an Iranian accession as donor.

Introgression libraries facilitate the identification of favorable exotic alleles or genomic regions, which can be exploited for improving elite breeding material. We evaluated the first two introgression libraries in rye (Secale cereale L.) on the phenotypic and molecular level. Our objectives were to detect candidate introgression lines (pre-ILs) with a better testcross performance than the recurrent parent and identify donor chromosome segments (DCS) responsible for the improved performance. We introduced DCS from the self-incompatible heterozygous exotic Iranian primitive rye accession Altevogt 14160 (donor) into the genetic background of the elite inbred line L2053-N (recurrent parent) by marker-assisted backcrossing and developed 40 BC(2)S(3) lines in each introgression library. Testcross performance for three agronomic and six quality traits was evaluated in replicated field trials across two testers at five locations over 2 years. The phenotypic effect of the DCS was analyzed for all traits. The pre-ILs had on average a testcross performance comparable to that of the recurrent parent. Significant (P < 0.05) differences between individual pre-ILs and the recurrent parent were detected for all traits except for heading date. For more than 60% of the significant (P < 0.05) differences, the pre-ILs were superior to the recurrent parent. For some pre-ILs, specific DCS were identified containing presumably quantitative trait loci responsible for the superior hybrid performance. Consequently, our study revealed that the development and employment of introgression libraries offers the opportunity for a targeted increase of genetic diversity of elite rye material for hybrid performance of agronomically important traits.

Iridium abundances across the ordovician-silurian stratotype.

Chemostratigraphic analyses in the Ordovician-Silurian boundary stratotype section, bracketing a major extinction event in the graptolitic shale section at Dob's Linn, Scotland, show persistently high iridium concentrations of 0.050 to 0.250 parts per billion. There is no iridiumn concentration spike in the boundary interval or elsewhere in the 13 graptolite zones examined encompassing about 20 million years. Iridium correlated with chromium, both elements showing a gradual decrease with time into the middle part of the Lower Silurian. The chromium-iridium ratio averages about 10(6). Paleogeographic and geologic reconstructions coupled with the occurrence of ophiolites and other deep crustal rocks in the source area suggest that the high iridium and chromium concentrations observed in the shales result from terrestrial erosion of exposed upper mantle ultramafic rocks rather than from a cataclysmic extraterrestrial event.

The effect of physiological conditions on the surface structure of proteins: setting the scene for human digestion of emulsions.

Understanding and manipulating the interfacial mechanisms that control human digestion of food emulsions is a crucial step towards improved control of dietary intake. This article reports initial studies on the effects of the physiological conditions within the stomach on the properties of the film formed by the milk protein (ß-lactoglobulin) at the air-water interface. Atomic force microscopy (AFM), surface tension and surface rheology techniques were used to visualize and examine the effect of gastric conditions on the network structure. The effects of changes in temperature, pH and ionic strength on a preformed interfacial structure were characterized in order to simulate the actual digestion process. Changes in ionic strength had little effect on the surface properties. In isolation, acidification reduced both the dilatational and the surface shear modulus, mainly due to strong repulsive electrostatic interactions within the surface layer and raising the temperature to body temperature accelerated the rearrangements within the surface layer, resulting in a decrease of the dilatational response and an increase of surface pressure. Together pH and temperature display an unexpected synergism, independent of the ionic strength. Thus, exposure of a pre-formed interfacial ß-lactoglobulin film to simulated gastric conditions reduced the surface dilatational modulus and surface shear moduli. This is attributed to a weakening of the surface network in which the surface rearrangements of the protein prior to exposure to gastric conditions might play a crucial role.

Biological behavior of CIN lesions is predictable by multiple parameter logistic regression models.

OBJECTIVES: Progression and regression of premalignant cervical lesions cannot be predicted using conventional cytomorphological or histomorphological parameters. However, markers such as human papillomavirus (HPV) or makers indicating proliferation, genetic instability and chromosomal aberration may be of predictive value assessing short-term biological behavior of cervical intraepithelial neoplasia. In this paper, we have studied the usage of logistic regression models with Ki-67 labeling index (LI), chromosome index for chromosome 1 (CI#1) and aneusomy for chromosome 1 in cervical smears to predict progressive and regressive behavior of premalignant cervical lesions. METHODS: Retrospectively, the intake smears of 42 women showing regression in follow-up and of 31 women showing progression in follow-up were assessed. RESULTS: A multiparameter logistic regression model containing the parameters Ki-67 LI, CI#1 and the fraction of cells with four copies of chromosome 1 per nucleus appeared to be the best predicting model, overall correct classification of 93.2% (area under the receiver operating characteristic curve 0.96 +/- 0.02). After cross-validation, the model correctly classified 66 of 73 samples (90.4%). Moreover, the model predicted biological behavior perfectly assessing the smear taken subsequently to the intake smear of 46 women. CONCLUSION: Although measuring parameters indicating proliferation and chromosome 1 aberration is laborious, this study demonstrates that short-term progressive and regressive behavior is highly predictable using a model combing these parameters. We also showed that in the triage management of high-risk human papillomavirus-positive women with minimally abnormal smears applying a model as such can be useful.

Effect of hydrocarbon chain and pH on structural and topographical characteristics of phospholipid monolayers.

Structural characteristics (structure, elasticity, topography, and film thickness) of dipalmitoyl phosphatidylcholine (DPPC) and dioleoyl phosphatidylcholine (DOPC) monolayers were determined at the air-water interface at 20 degrees C and pH values of 5, 7, and 9 by means of surface pressure (pi)-area (A) isotherms combined with Brewster angle microscopy (BAM) and atomic force microscopy (AFM). From the pi-A isotherms and the monolayer elasticity, we deduced that, during compression, DPPC monolayers present a structural polymorphism at the air-water interface, with the homogeneous liquid-expanded (LE) structure; the liquid-condensed structure (LC) showing film anisotropy and DPPC domains with heterogeneous structures; and, finally, a homogeneous structure when the close-packed film molecules were in the solid (S) structure at higher surface pressures. However, DOPC monolayers had a liquid-expanded (LE) structure under all experimental conditions, a consequence of weak molecular interactions because of the double bond of the hydrocarbon chain. DPPC and DOPC monolayer structures are practically the same at pH values of 5 and 7, but a more expanded structure in the monolayer with a lower elasticity was observed at pH 9. BAM and AFM images corroborate, at the microscopic and nanoscopic levels, respectively, the same structural polymorphism deduced from the pi-A isotherm for DPPC and the homogeneous structure for DOPC monolayers as a function of surface pressure and the aqueous-phase pH. The results also corroborate that the structural characteristics and topography of phospholipids (DPPC and DOPC) are highly dependent on the presence of a double bond in the hydrocarbon chain.

Assessment of mandibular invasion of squamous cell carcinoma by various modes of imaging: constructing a diagnostic algorithm.

The aim of this study was to determine the optimal combination of preoperative examination methods to predict mandibular invasion by squamous cell carcinoma of the oral cavity. Data were gathered prospectively but evaluated retrospectively. The preoperative results of clinical examination, conventional radiography, bone single photon emission computed tomography (SPECT), computed tomography and magnetic resonance imaging were compared to the histological results of resection specimens from 67 patients with tumours, adjacent or fixed to the mandible, histologically confirmed as squamous cell carcinoma. The examination methods with acceptable sensitivity and specificity were selected and diagnostic algorithms were constructed using all possible combinations. The preferred diagnostic algorithm was found to be either computed tomography or magnetic resonance imaging, followed by a bone SPECT in cases where the first scan is negative. A negative bone SPECT rules out mandibular invasion (100% sensitivity). This algorithm accurately predicted mandibular invasion in 85% of the patients, without yielding false negative results. In this study group, application of such an algorithm would have resulted in a reduction of the number of unnecessary mandibular resections by 50%. The suggested, preferred, diagnostic algorithm shortens the preoperative screening process, avoiding unnecessary costs, as well as considerably reducing the number of unnecessary mandibular resections.

Pectin Conformation in Solution.

The interplay of degree of methylesterification (DM), pH, temperature, and concentration on the macromolecular interactions of pectin in solution has been explored. Small-angle X-ray scattering complemented by atomic force microscopy and molecular dynamics was employed to probe chain dimensions and solution structure. Two length scales have been observed with the first level of structure characterising chain clusters with sizes ranging between 100-200 nm. The second level of structure arises from single biopolymer chains with a radius of gyration between ∼6 and 42 nm. The development of a range of macromolecular dimensions in vitro and in silico shows that the chain flexibility increases with DM and at acidic pH, whereas hydrogen bonding is the responsible thermodynamic driving force for cluster formation. High methyl pectins create structures of lower fractal dimension with less efficient packing. This work unveils pectin conformations covering most of its industrially and biologically relevant environments, enabling rational design of advanced biomaterials based on pectin.

Echocardiographic features of cardiac failure in Uganda.

Cardiac failure is a common medical presentation in Uganda. This study primarily focuses on the aetiology of heart failure in 65 adult patients and assesses the utility of echocardiography in a resource-limited setting. Our findings suggest that endomyocardial fibrosis is much less prevalent than previously described in other regions of Uganda and highlights the need for more basic descriptive studies on common presenting illnesses in rural Africa.

Understanding surface reactivity of Si electrodes in Li-ion batteries by in operando scanning electrochemical microscopy.

In operando SECM is employed to monitor the evolution of the electrically insulating character of a Si electrode surface during (de-)lithiation. The solid-electrolyte interface (SEI) formed on Si electrodes is shown to be intrinsically electrically insulating. However, volume changes upon (de-)lithiation lead to the loss of the protecting character of the initially formed SEI.

Juxtacortical chondrosarcoma of the mandible: report of a unique case and review of the literature.

The clinical, radiographic, and pathological features of a juxtacortical chondrosarcoma of the mandible in a 25-year-old Caucasian woman are presented and the differential diagnostic aspects are discussed. To the best of our knowledge, this rare tumor has not previously been reported in the maxillofacial skeleton. Ten years after surgery there is no evidence of local recurrence or metastatic disease. As the prognosis of juxtacortical chondrosarcoma of the long bones seems to be relatively favorable compared with the usual central chondrosarcoma of similar grade of malignancy, this might also be expected for a similar tumor presentation in the maxillofacial skeleton.

Thymic cyst in the neck.

A rare case of a thymic cyst in the neck containing both thymus and parathyroid tissue in a 7-year-old boy is presented. The clinical presentation, diagnostic evaluation, surgical management and histopathological features are described. The embryology of cervical thymic cysts and the differential diagnosis of cystic neck masses in children are briefly reviewed. The diagnosis is seldom made preoperatively. Surgical resection is the treatment of choice for definitive diagnosis, resolution of symptoms and cure.

Down regulation of estrogen receptor expression is an early event in human papillomavirus infected cervical dysplasia.

PURPOSE: To study the alterations in hormonal sensitivity in relation to proliferative activity during the development of cervical dysplasia in women infected with high-risk human papillomavirus (hr-HPV). METHODS: Three to five biopsies of the cervix of eight patients were taken at colposcopy. Dysplasia was detected in 22 of the 32 biopsies, and 20 of these 22 biopsies contained hr-HPV. The labeling index (LI) as well as the intensity of staining of the MIB-1-, estrogen receptor (ER)-, and progesterone receptor (PR)-expression was assessed in each biopsy, including normal epithelium directly adjacent to the dysplastic lesions. RESULTS: Statistical analysis showed a significant increase in the MIB-1 LI with increasing severity of the dysplasia. The ER LI and ER intensity of staining in dysplastic lesions, as well as in morphologically normal epithelium directly adjacent to the dysplasia, showed a significant inverse relation with the severity of the dysplasia. The PR LI and intensity of staining did not differ between normal epithelium and dysplasia. The ER/MIB-1 ratio (including the ER LI and ER intensity of staining), and the PR/MIB-1 ratio (intensity of staining only) in dysplastic lesions showed a significant inverse relation with the severity of the dysplasia, while no alterations in these ratios were observed in morphologically normal epithelium adjacent to the dysplasia. CONCLUSION: Down regulation of ER expression may be the first alteration to take place in normal epithelium during the development of cervical dysplasia in women infected with hr-HPV. The significant decrease in the ER/MIB-1-, and PR/MIB-1-ratio in progressively dysplastic lesions indicates a loss of normal growth control by sex steroid hormones, which is not observed in normal epithelium.

[Premalignant lesions of the oral mucosa. Prognosis, treatment and follow-up]. / Premaligne slijmvliesafwijkingen in de mondholte. Prognose, behandeling en vervolg.

To consider the value of prognostic factors in the development of a squamous cell carcinoma from a leukoplakia of the oral mucosa, a retrospective study was performed. Clinical and histological data of 104 patients with oral leukoplakia were analyzed. Leukoplastic lesions with dysplasia in the initial biopsy (n = 38) had been treated by excision (n = 28), by laser evaporation (n = 6) or a combination of these treatments (n = 4). Non-dysplastic lesions (n = 66) had been excised (n = 48), evaporised (n = 17) or treated by excision as well as laser evaporation (n = 1). During follow-up of maximal 6 years (mean 3.6 years), 12 patients had developed an infiltrative squamous cell carcinoma at the site of the primary lesion, 2 within a period of 24 months. No relation could be found between on the one hand size (p > 0.2), clinical aspect (p > 0.2), location (p > 0.45), and primary treatment (p > 0.15) of the lesion, and on the other hand the risk of developing a squamous cell carcinoma. Only a relation could be found between (the intensity of) dysplasia and the development of a squamous cell carcinoma (p < 0.001). It was concluded that because of the high risk of developing a squamous cell carcinoma, patients with a dysplastic mucosal oral lesion should be followed during a prolonged time.

CT and diffusion-weighted MR imaging in randomized order: diffusion-weighted imaging results in higher accuracy and lower interrater variability in the diagnosis of hyperacute ischemic stroke.

BACKGROUND AND PURPOSE: Diffusion-weighted MRI (DWI) has become a commonly used imaging modality in stroke centers. The value of this method as a routine procedure is still being discussed. In previous studies, CT was always performed before DWI. Therefore, infarct progression could be a reason for the better result in DWI. METHODS: All hyperacute (<6 hours) stroke patients admitted to our emergency department with a National Institutes of Health Stroke Scale (NIHSS) score >3 were prospectively randomized for the order in which CT and MRI were performed. Five stroke experts and 4 residents blinded to clinical data judged stroke signs and lesion size on the images. To determine the interrater variability, we calculated kappa values for both rating groups. RESULTS: A total of 50 patients with ischemic stroke and 4 patients with transient symptoms of acute stroke (median NIHSS score, 11; range, 3 to 27) were analyzed. Of the 50 patients, 55% were examined with DWI first. The mean delay from symptom onset until CT was 180 minutes; that from symptom onset until DWI was 189 minutes. The mean delay between DWI and CT was 30 minutes. The sensitivity of infarct detection by the experts was significantly better when based on DWI (CT/DWI, 61/91%). Accuracy was 91% when based on DWI (CT, 61%). Interrater variability of lesion detection was also significantly better for DWI (CT/DWI, kappa=0.51/0.84). The assessment of lesion extent was less homogeneous on CT (CT/DWI, kappa=0.38/0.62). The differences between the 2 modalities were stronger in the residents' ratings (CT/DWI: sensitivity, 46/81%; kappa=0.38/0.76). CONCLUSIONS: CT and DWI performed with the same delay after onset of ischemic stroke resulted in significant differences in diagnostic accuracy. DWI gives good interrater homogeneity and has a substantially better sensitivity and accuracy than CT even if the raters have limited experience.

Trigeminal neuropathy secondary to perineural invasion of head and neck carcinomas.

Perineural spread of head and neck cancer is an uncommon cause of cranial neuropathy. We studied five patients with cranial neuropathy resulting from perineural spread of head and neck carcinomas. Trigeminal neuropathy with facial pain or paresthesias was the most common clinical manifestation. MRI in the coronal plane under gadolinium enhancement established the diagnosis by visualization of the lower divisions of the trigeminal nerve. Perineural tumor spread can cause headaches in patients with head and neck cancer.

The effect of cholesterol reduction on the endothelial function and progression of atherosclerosis in WHHL rabbits.

In 3-month-old homozygous Watanabe heritable hyperlipidemic (WHHL) rabbits the effect of treatment with the 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor pravastatin was studied for 9 months and related to the endothelial function of the coronary arteries of isolated hearts and rings of the distal abdominal aorta. Oral administration of pravastatin in doses up to 40 mg/kg per day significantly decreased plasma cholesterol by 51% in comparison to untreated WHHL rabbits. Basal coronary flow and bradykinin-induced increase in coronary flow in Langendorff hearts of the pravastatin-treated animals were significantly greater than the flow in the control animals, whereas the metacholine-induced relaxation of abdominal aortic rings was not different and attenuated in comparison to New Zealand white rabbits. The incidence of atherosclerotic lesions in four main coronary arteries and the aorta was significantly lower in the pravastatin treated animals (25.0% and 52.8% respectively) than in untreated WHHL rabbits (34.1% and 80.0% respectively). The mean percentage of narrowing in the aorta was also significantly lower in the pravastatin-treated group (12.0%) than in the controls (25.2%). Significant correlations were found between the extent of atherosclerotic lesions and the bradykinin-induced increase in coronary flow versus plasma total cholesterol levels. Thus, in this model, long term cholesterol lowering treatment with pravastatin starting at an early age retards the progression of plaque formation and preserves the endothelium-dependent relaxation of the coronary arteries.