Bond strength and marginal adaptation of resin composites and correlations with clinical results.

OBJECTIVES: Due to innumerable confounding factors and a high number of types and brands of dental restorative materials, the clinical performance of restorative materials are sought predicted by various in vitro tests. However, only few such tests have been found to correlate well with clinical findings. Thus, the present study determined the in vitro dentin bond strength and marginal adaptation of Class II restorations and correlated the results to their clinical outcomes. METHODS: Dentin bond strength (µTBS and µSBS) and marginal gap formation of Class II restorations (replica technique and SEM) were measured after 24 h and 6 m water storage using eight combinations of adhesive and resin composite. Clinical outcomes (mean survival time, Hazard Ratio, annual failure rate; n = 10.695) were gained from a data set of a retrospective multicenter study of direct restorations. RESULTS: Significant differences were found for dentin bond strength and marginal gap formation between the restorative material groups, and negative effects of long-term storage were observed. µTBS correlated significantly with certain clinical outcomes of Class I restorations, while µSBS correlated with certain clinical outcomes of Class II, III, IV and V restorations. Marginal gap formation in enamel and number of paramarginal fractures correlated with certain clinical outcomes of Class II restorations. SIGNIFICANCE: Using the same restorative materials in vitro as in vivo, gave significant, but weak correlations between in vitro bond strength or marginal adaptation and clinical outcomes, lending support to the use of in vitro tests in early stages of material selection.

Stochastic modeling to identify requirements for centralized monitoring of distributed wastewater treatment.

Distributed (decentralized) wastewater treatment can, in many situations, be a valuable alternative to a centralized sewer network and wastewater treatment plant. However, it is critical for its acceptance whether the same overall treatment performance can be achieved without on-site staff, and whether its performance can be measured. In this paper we argue and illustrate that the system performance depends not only on the design performance and reliability of the individual treatment units, but also significantly on the monitoring scheme, i.e. on the reliability of the process information. For this purpose, we present a simple model of a fleet of identical treatment units. Thereby, their performance depends on four stochastic variables: the reliability of the treatment unit, the respond time for the repair of failed units, the reliability of on-line sensors, and the frequency of routine inspections. The simulated scenarios show a significant difference between the true performance and the observations by the sensors and inspections. The results also illustrate the trade-off between investing in reactor and sensor technology and in human interventions in order to achieve a certain target performance. Modeling can quantify such effects and thereby support the identification of requirements for the centralized monitoring of distributed treatment units. The model approach is generic and can be extended and applied to various distributed wastewater treatment technologies and contexts.

Network condition simulator for benchmarking sewer deterioration models.

An accurate description of aging and deterioration of urban drainage systems is necessary for optimal investment and rehabilitation planning. Due to a general lack of suitable datasets, network condition models are rarely validated, and if so with varying levels of success. We therefore propose a novel network condition simulator (NetCoS) that produces a synthetic population of sewer sections with a given condition-class distribution. NetCoS can be used to benchmark deterioration models and guide utilities in the selection of appropriate models and data management strategies. The underlying probabilistic model considers three main processes: a) deterioration, b) replacement policy, and c) expansions of the sewer network. The deterioration model features a semi-Markov chain that uses transition probabilities based on user-defined survival functions. The replacement policy is approximated with a condition-class dependent probability of replacing a sewer pipe. The model then simulates the course of the sewer sections from the installation of the first line to the present, adding new pipes based on the defined replacement and expansion program. We demonstrate the usefulness of NetCoS in two examples where we quantify the influence of incomplete data and inspection frequency on the parameter estimation of a cohort survival model and a Markov deterioration model. Our results show that typical available sewer inventory data with discarded historical data overestimate the average life expectancy by up to 200 years. Although NetCoS cannot prove the validity of a particular deterioration model, it is useful to reveal its possible limitations and shortcomings and quantifies the effects of missing or uncertain data. Future developments should include additional processes, for example to investigate the long-term effect of pipe rehabilitation measures, such as inliners.

Modelling seasonal dynamics of "Microthrix parvicella".

The filamentous bacteria "Microthrix parvicella" can cause serious bulking and scumming in wastewater treatment plants (WWTPs) all over the world. Decades of research have identified Microthrix as a specialized lipid consumer but could not clarify the processes that allow this organism to successfully compete in activated sludge systems. In this study we developed a model, based on ASM3, that describes the pronounced seasonal variations of Microthrix abundance observed in a full-scale WWTP. We hypothesize that low temperatures reduce the solubility of lipids and inhibit their uptake by non-specialized bacteria. The presented model structure and parameters successfully fit the measured data; however they do not necessarily reflect the only and true selection mechanism for Microthrix. This model is not yet to be used for prediction; it is rather a valuable research tool to coordinate the discussion and plan future research activities in order to identify the relevant selection mechanisms favoring Microthrix in activated sludge systems.

[Supracondylar traction of a pertrochanteric femur fracture in a patient amputated below the knee]. / Suprakondyläre Extension einer pertrochantären Femurfraktur bei einem Patienten mit Unterschenkelamputation.

Pertrochanteric femur fracture is rare in patients with lower leg amputation. Using supracondylar traction takes full advantage of the extension table. Intraoperative insertion of a Steinmann pin for traction is a well-known low-risk procedure. In our opinion, this kind of extension is a simple procedure that carries no risks for postoperative prosthetic management in patients with lower leg amputation.

On-line monitoring of adhesion and proliferation of cultured hepatoma cells using optical waveguide lightmode spectroscopy (OWLS).

Monitoring of cell adhesion, cell spreading, and cell proliferation opens attractive perspectives in the on-line control of monolayer cell cultures in toxicity tests, in bioreactors as used for the serial production of skin grafts, or in extracorporeal liver devices. In this study the hepatoma Hep G2 cell adhesion and proliferation was monitored using an integrated optical method, optical waveguide lightmode spectroscopy (OWLS). This method is based upon refractive index measurements within a 100-nm thin layer above a Si(Ti)O(2) surface on which the cells were cultured and exposed to cytotoxic and cytostatic agents. The OWLS signal was proportional to cell density during the spreading period (4 h), and in long-term experiments (46 h) the OWLS signal correlated on a logarithmic scale with cell density. After administration of the protein synthesis inhibitor cycloheximide (4 microg/mL) to fully spread hepatoma cells, cell growth was arrested and change of the OWLS signal became noticeable within 6 h after drug administration. For exposure to increasing concentrations of the anticancer drug cyclophosphamide (2.5-20 mM) a concentration-dependent reduction of the OWLS signal was found. For cycloheximide and cyclophospamide the OWLS signal was also confirmed by cell viability measurements using the neutral red assay, the thiazolylblue tetrazoliumbromide assay, total protein measurements, and cell morphology. It was demonstrated that the OWLS signal detects minor changes in cell adhesion, which serve as indicators of metabolic state and growth behavior. OWLS is thus a quantitative tool to characterize impaired cell growth mediated by culture medium, by extracellular matrix, or after exposure to a toxin.

Optical waveguide lightmode spectroscopy (OWLS) to monitor cell proliferation quantitatively.

The use of microscopic observations used for in situ monitoring of cell proliferation in the production of epidermal autografts is not satisfactory. In particular, the identification of the projected cell area from microscopic pictures by image analysis (IA) depends on intensity edges and level of contrasts and is thus limited to subconfluent cultures. Some of these problems can be solved by using optical waveguide lightmode spectroscopy (OWLS), which measures the effective refractive index of a thin layer above an Si(Ti)O(2) waveguide surface. In this study the use of OWLS to monitor cell adhesion, spreading, and growth was studied. The sensitivity of the method was investigated by using three different cell lines, two fibroblasts and one hepatoma cell line. Cell proliferation of two strains of fibroblasts and hepatoma cells was monitored up to 2 days with the OWLS. In parallel, cell density was determined at different time points microscopically using an additional window in the measuring chamber. The cell density of fully spread cells ( approximately 4 h after attachment) was found to be proportional to the OWLS signal. In long-term cultures the influence of the cell density from single cells to confluent cell cultures upon the OWLS signal was investigated. The exponentially growing number of hepatoma resulted in a linear increase of the sensor signal. Due to this and to the fact that the proliferating cells exhibit contact inhibition, it was concluded that the cell contact area must decrease exponentially. The results show the strength of OWLS for monitoring the adhesion and proliferation of anchorage-dependent cells in applications where an on-line indicator of the total biomass is needed. Additionally, OWLS provides metabolic information through detection of the cell mass in close contact with the waveguide.

Optical waveguide lightmode spectroscopy as a new method to study adhesion of anchorage-dependent cells as an indicator of metabolic state.

Optical Waveguide Lightmode Spectroscopy (OWLS) is based on measurements of the effective refractive index of a thin layer above the waveguide. Its potential as a whole-cell biosensor was demonstrated recently monitoring adhesion and spreading of Baby Hamster Kidney (BHK) cells on-line. In this work the OWLS is shown to be a promising tool to study the adhesion, morphology and metabolic state of fibroblasts in real time. A new design of the measuring chamber allowed simultaneous observation by phase-contrast microscopy and made the adsorbed cell density controllable and reproducible. The OWLS signal correlated quantitatively with the contact-area between the fibroblasts and the waveguide. The OWLS signals for adhesion and spreading of three different fibroblast cell lines were in good agreement with their morphology identified by phase-contrast microscopy. The cell adhesion and cell shape changes were examined in three scenarios: (a) serum-induced spreading of the surface attached fibroblasts was followed until it was completed, and the OWLS signal remained constant for over 12 h; (b) the fully spread cells were exposed to the microtubuli-disrupting colchicine and a decrease of the OWLS signal was monitored; (c) in a similar experiment with benzalkonium chloride, a strong skin irritant, a concentration-dependent response of the signal was found. The results show the strength of the OWLS method for monitoring the adhesion behavior of anchorage-dependent cells such as fibroblasts. It has a great potential as a whole-cell biosensor for high throughput screening in toxicology.

Autosomal dominant inheritance of a negative electroretinogram phenotype in three generations.

PURPOSE: We report an abnormal electroretinogram with a negative configuration in a child who presented with moderate myopia, nystagmus, and visual developmental delay. We investigated the electroretinogram and explored the possibility of a metabotropic glutamate receptor subtype 6 mutation in six family members spanning four generations. METHODS: Case report and family study: Complete eye examinations and Ganzfeld electroretinograms were recorded from the maternal great-grandmother, maternal grandmother, mother, uncle, and sibling of the 7-month-old female proband. The electroretinogram was repeated in the proband at 17 months of age. Dark adaptometry was performed in all adult subjects. Fundus photographs and visual field examinations were administered to the grandmother and mother. The metabotropic glutamate receptor subtype 6 gene was amplified and sequenced in all affected subjects. RESULTS: The proband had a negative electroretinogram and a normal fundus. The maternal grandmother, uncle, and mother had an abnormal electroretinogram identical to the proband yet had no visual complaints. The ophthalmology examinations in the adult subjects were normal, and subsequent examination of the proband at 17 months, 5 years, and 6.5 years of age showed no changes in the fundus or refractive error. Her nystagmus resolved by 5 years of age. Rod threshold and visual fields were normal in the affected adult subjects. No mutation in the metabotropic glutamate receptor subtype 6 gene was found. CONCLUSIONS: In this family, a negative electroretinogram was not associated with decreased rod threshold, visual acuity loss, visual field loss, muscle disease, or metabotropic glutamate receptor subtype 6 mutation. Additional study will be required to understand the nature of the negative electroretinogram phenotype in this family.

Clinical and electroretinographic findings in fetal alcohol syndrome.

PURPOSE: Fetal exposure to alcohol is a serious public health problem and is associated with anomalies of the eye ground, as well as neurodevelopmental delay, growth delay, and characteristic facial features. Our purpose is to report the incidence of abnormal electroretinogram (ERG) results in children with fetal alcohol syndrome and raise awareness of the diagnosis of fetal alcohol syndrome in ophthalmology. METHODS: A retrospective review was performed on the records of 11 children with the diagnosis of fetal alcohol syndrome. The results of the ophthalmologic examination, magnetic resonance imaging, visual acuity test, and ERG are reported. RESULTS: The magnetic resonance imaging results were abnormal in all subjects tested. The ophthalmology examination showed optic nerve hypoplasia in 91% of the subjects. Visual acuity was reduced in all but one subject. The ERG results were abnormal, showing reduced b-wave amplitude, increased a- and b-wave implicit time, reduced Rmax, and increased log (k). The scotopic ERG was more severely affected than the photopic ERG. CONCLUSIONS: Prenatal alcohol exposure can lead to changes in retinal function as evidenced by an abnormal ERG response. The ERG can therefore be a tool with which to identify suspected alcohol embryopathy.

Actin-dependent activation of ion conductances in bronchial epithelial cells.

Activation of Cl- and K+ channels is necessary to drive ion secretion in epithelia. There is substantial evidence from previous reports that vesicular transport and exocytosis are involved in the regulation of ion channels. In the present study we examined the role of cytoskeletal elements and components of intracellular vesicle transport on ion channel activation in bronchial epithelial cells. To this end, cells were incubated with a number of different compounds which interact with either microtubules or actin microfilaments, or which interfere with vesicle transport in the Golgi apparatus. The effectiveness of these agents was verified by fluorescence staining of cellular microtubules and actin. The function was examined in 36Cl- efflux studies as well as in whole-cell (WC) patch-clamp and cell-attached studies. The cells were studied under control conditions and after exposure to (in mmol/l) ATP (0.1), forskolin (0.01), histamine (0.01) and hypotonic bath solution (HBS, NaCl 72.5). In untreated control cells, ATP primarily activated a K+ conductance whilst histamine and forskolin induced mainly a Cl- conductance. HBS activated both K+ and Cl- conductances. Incubation of the cells with brefeldin A (up to 100 mumol/l) did not inhibit WC current activation and 36Cl- efflux. Nocodazole (up to 170 mumol/l) reduced the ATP-induced WC current, and mevastatin (up to 100 mumol/l) the cell-swelling-induced WC current. Neither had any effect on the WC current induced by forskolin and histamine. Also 36Cl- efflux induced by HBS, ATP, forskolin and histamine was unaltered by these compounds.(ABSTRACT TRUNCATED AT 250 WORDS)

cAMP-dependent activation of ion conductances in bronchial epithelial cells.

The cAMP-dependent activation of Cl- channels was studied in a bronchial epithelial cell line (16HBE14o-) in fast and slow whole-cell, and cell-attached patch-clamp experiments. The cells are known to express high levels of cystic fibrosis transmembrane conductance regulator mRNA and protein. Isoproterenol, forskolin and histamine (all 10 mumol/l) reversibly and significantly depolarized the membrane voltage (Vm) and increased the whole-cell Cl- conductance significantly by 34.0 +/- 0.9 (n = 3), 18.1 +/- 2.7 (n = 50), and 25 +/- 4.5 (n = 37) nS respectively. The effect of histamine was blocked by cimetidine (10 mumol, n = 5) but not by diphenhydramine (10 mumol/l, n = 4), which suggests binding of histamine to H2 receptors. The forskolin-induced current was not inhibited significantly by 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (0.5 mmol/l, n = 9) nor glibenclamide (10 mumol/l, n = 3) and had an anion-permeability sequence of Cl = Br- > I- (n = 9). In cell-attached recordings forskolin (10 mumol/l) increased the conductance of the patched membrane from 65.5 +/- 13.6 pS to 150.8 +/- 33.2 pS (n = 30). Although the conductance was increased significantly, clear ion channel events occurring in parallel with the current activation were not detected in the cell-attached membrane. In 4 out of 30 cell-attached recordings single-channel currents were observed. These channels, with a single-channel conductance of about 6 pS, were already active before forskolin was added. No effect of forskolin on the channel amplitude, open probability or kinetics of these channels was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Ca(2+)- and swelling-induced activation of ion conductances in bronchial epithelial cells.

The present study was performed to examine Ca(2+)-dependent and cell-swelling-induced ion conductances in a polarized bronchial epithelial cell line (16HBE14o-). Whole-cell currents were measured in fast and slow whole-cell patch-clamp experiments in cells grown either on filters or on coated plastic dishes. In addition the transepithelial voltage (Vte) and resistance (Rte) were measured in confluent monolayers. Resting cells had a membrane voltage (Vm) of -36 +/- 1.1 mV (n = 137) which was mainly caused by K+ and Cl- conductances and to a lesser extent by a Na+ conductance. Vte was apical-side-negative after stimulation. Equivalent short-circuit (Isc = Vte/Rte) was increased by the secretagogues histamine (0.1 mmol/l), bradykinin (0.1 - 10 mumol/l). and ATP (0.1 - mumol/l). The histamine-induced Is was blocked by either basolateral diphenhydramine (0.1 mmol/l, n = 4) or apical cimetidine (0.1 mmol/l, n = 4). In fast and slow whole-cell recordings ATP and bradykinin primarily activated a transient K+ conductance and hyperpolarized Vm. This effect was mimicked by the Ca2+ ionophore ionomycin (1 mumol/l, n = 11). Inhibition of the bradykinin-induced Isc by the blocker HOE140 (1 mumol/l, n = 3) suggested the presence of a BK2 receptor. The potency sequence of different nucleotide agonists on the purinergic receptor was UTP approximately ATP > ITP > GTP approximately CTP approximately [beta, gamma-methylene] ATP approximately 2-methylthio-ATP = 0 and was obtained in Isc measurements and patch-clamp recordings. This suggests the presence of a P2u receptor. Hypotonic cell swelling activated both Cl- and K+ conductances.(ABSTRACT TRUNCATED AT 250 WORDS)