Influence of root parallelism on the stability of extraction-site closures

Introduction: In premolar extraction cases, root parallelism is recommended to preserve the stability of space closures. The influence of the degree of root parallelism on relapse of tooth extraction spaces has been a controversial topic in the literature. The aim of this study was to compare the angle between the long axes of the canine and the second premolarin patients with and without stability of extraction-space closures. Methods: A sample of 56 patients, treated with 4 premolar extractions, was divided into 2 groups: group 1, consisting of 25 patients with reopening of extraction spaces; and group 2, consisting of 31 patients without reopening of extraction spaces. Panoramic radiographs of each patient were analyzed at the posttreatment and 1-year posttreatment stages. The data were statistically analyzed by using chi-square tests, t tests, analysis of variance (ANOVA), and Pearson correlation coefficients. Results: The results showed that the groups did not differ regarding the angle between the canine and the second premolar, and there was no correlation between angular changes and reopening of extraction spaces, showing that dental angular changes are not determining factors for relapse, and other factors should be investigated. Conclusions: The final angle and the posttreatment changes observed in the angle between the long axes of the canine and the second premolar showed no influence on the relapse of extraction spaces. (Am J Orthod Dentofacial Orthop 2011; 139: e505-e510)

Atypical extraction of maxillary central incisors

This case report describes a Class I crowded malocclusion with an ankylosed maxillary central incisor that was in infraocclusion and labially displaced. The patient had wide maxillary teeth, and the option of extracting the maxillary central incisors followed by space closure, with lateral incisors substituting for the central incisors, was chosen. (Am J Orthod Dentofacial Orthop 2010;138:510-7)

Comparison of oral versus sublingual piroxicam during postoperative pain management after lower third molar extraction

In this study, 53 patients received piroxicam, administered orally or sublingually, after undergoing removal of symmetrically positioned lower third molars, during two separate appointments. This study used a randomized, blind, cross-over protocol. Objective and subjective parameters were recorded for comparison of postoperative results for 7 days after surgery. Patients treated with oral or sublingual piroxicam reported low postoperative pain scores. The patients who received piroxicam orally took a similar average amount of analgesic rescue medication compared with patients who received piroxicam sublingually (p > 0.05). Patients exhibited similar values for mouth opening measured just before surgery and immediately following suture removal 7 days later (p > 0.05), and showed no significant differences between routes of piroxicam administration for swelling control during the second or seventh postoperative days (p > 0.05). In summary, pain, trismus and swelling after lower third molar extraction, independent of surgical difficulty, could be controlled by piroxicam 20 mg administered orally or sublingually and no significant differences were observed between the route of delivery used in this study.

Extraction and purification of the zwitterions cylindrospermopsin and deoxycylindrospermopsin from Cylindrospermopsis raciborskii

The hepatotoxin cylindrospermopsin (CYN) has been isolated from the cyanobacterium Cylindrospermopsis raciborskii (C. raci.). Efforts to study this toxin have been hampered by the time-consuming requirement to extract it from cultures of the organism. It is usually extracted from lyophilized cells collected from a laboratory culture. Our preliminary work suggested far more of the toxin is available in solution in the culture media than in the cells collected. We have therefore investigated the use of commercially available solid phase extraction sorbents to extract CYN from culture media in which C. raci. has been grown. A range of reverse phase and ion-exchange sorbents were tested across a range of pHs for their ability to retain CYN without success. Subsequently, graphitized carbon cartridges were found to retain CYN strongly. Elution with 5% formic acid in methanol allowed the CYN to be regained for final purification by HPLC. Deoxy-CYN, an analog of CYN can also be extracted using this procedure. (C) 2001 John Wiley & Sons, Inc.

Anthropogenic and Natural Organohalogen Compounds in Blubber of Dolphins and Dugongs (Dugong dugon) from Northeastern Australia

A range of organohalogen compounds (10 polychlorinated biphenyl [PCB] congeners, DDT and metabolites, chlordane-related compounds, the potential natural organochlorine compound Q1, toxaphene, hexachlorobenzene, hexachlorocyclohexanes, dieldrin, and several yet unidentified brominated compounds) were detected in the blubber of four bottlenose dolphins (Tursiops truncatus), one common dolphin (Delphinus delphis), and seven dugongs (Dugong dugon), as well as in adipose tissue of a green turtle (Chelonia mydas) and a python (Morelia spilota) from northeast Queensland (Australia). The green turtle and dugongs accumulated lower organohalogen levels than the dolphins. Lower levels in dugongs were expected because this species is exclusively herbivorous. Highest PCB and DDT levels recorded in dugongs were 209 and 173 mug/kg lipids, respectively. Levels of the nonanthropogenic heptachlorinated compound Q1 (highest level in dugongs was 160 mug/kg lipids) were estimated using the ECD response factor of trans-nonachlor. Highest organohalogen levels were found in blubber of dolphins for sumDDT (575-52,500 mug/kg) and PCBs (600-25,500 mug/kg lipids). Furthermore, Q1 was a major organohalogen detected in all samples analyzed, ranging from 450 -9,100 mug/kg lipids. The highest concentration of Q1 determined in this study represents the highest concentration reported to date in an environmental sample. Levels of chlordane-related compounds were also high (280-7,700 mug/kg, mainly derived from trans-nonachlor), but concentrations of hexachlorobenzene, hexachlorocyclohexanes, dieldrin, and toxaphene were relatively low and contributed little to the overall organohalogen contamination. Furthermore, a series of three major (BC-1, BC-2, and BC-3) and six minor (BC-4 through BC-9) unknown brominated compounds were observable by extracting m/z 79 and m/z 81 from the GC/ECNI-MS full scan run. Structural proposals were made for the two major recalcitrant compounds (referred to as BC-1 and BC-2). BC-2 appears to be a tetrabromo-methoxy-diphenylether (512 u) and BC-1 has 14 u (corresponding with an additional CH2 group) more relative to BC-1. In general the organohalogen pattern observed in blubber of dolphins was different compared to similar samples from other locations in the world, which is apparent from the fact that the four major abundant signals in the GC/ECD chromatogram. of D. delphis originated from the four unknown compounds Q1, BC-1, BC-2, and BC-3.

A sensitive and specific assay for glutathione with potential application to glutathione disulphide, using high-performance liquid chromatography-tandem mass spectrometry

We have utilised the combination of sensitivity and specificity afforded by coupling high-performance liquid chromatography (HPLC) to a tandem mass spectrometer (MS-MS) to produce an assay which is suitable for assaying glutathione (GSH) concentrations in liver tissue. The sensitivity suggests it may also be suitable for extrahepatic tissues, The method has been validated for GSH using mouse liver samples and also allows the assay of GSSG. The stability of GSH under conditions relevant to the assay has been determined. A 20-mul amount of a diluted methanol extract of tissue is injected with detection limits of 0.2 pmol for GSH and 2 pmol for GSSG. The HPLC uses an Altima C-18 (150X4.6 mm, 5 mum) column at 35 degreesC. Chromatography utilises a linear gradient from 0 to 10% methanol in 0.1% formic acid over 5 min, with a final isocratic stage holding at 10% methanol for 5 min. Total flow rate is 0.8 ml/min. The transition from the M+H ion (308.1 m/z for GSH, and 613.3 m/z for GSSG) to the 162.0 m/z (GSH) and 355.3 m/z (GSSG) fragments are monitored. (C) 2001 Elsevier Science B.V. All rights reserved.

Quantitative affinity chromatography

The objective of this review is to summarize developments in the use of quantitative affinity chromatography to determine equilibrium constants for solute interactions of biological interest. Affinity chromatography is an extremely versatile method for characterizing interactions between dissimilar reactants because the biospecificity incorporated into the design of the affinity matrix ensures applicability of the method regardless of the relative sizes of the two reacting solutes. Adoption of different experimental strategies, such as column chromatography, simple partition equilibrium experiments, solid-phase immunoassay, and biosensor technology, has led to a situation whereby affinity chromatography affords a means of characterizing interactions governed by an extremely broad range of binding affinities-relatively weak interactions (binding constants below 10(3) M-1) through to interactions with binding constants in excess of 10(9) M-1. In addition to its important role in solute separation and purification, affinity chromatography thus also possesses considerable potential for investigating the functional roles of the reactants thereby purified. (C) 2001 Elsevier Science B.V. All rights reserved.

A new method of threshold voltage extraction via MOSFET gate-to-substrate capacitance measurement

A new method to extract MOSFET's threshold voltage VT by measurement of the gate-to-substrate capacitance C-gb of the transistor is presented. Unlike existing extraction methods based on I-V data, the measurement of C-gb does not require de drain current to now between drain and source thus eliminating the effects of source and drain series resistance R-S/D, and at the same time, retains a symmetrical potential profile across the channel. Experimental and simulation results on devices with different sizes are presented to justify the proposed method.

Dopant extraction from scanning capacitance microscopy measurements of p-n junctions using combined inverse modeling and forward simulation

This article proposes a more accurate approach to dopant extraction using combined inverse modeling and forward simulation of scanning capacitance microscopy (SCM) measurements on p-n junctions. The approach takes into account the essential physics of minority carrier response to the SCM probe tip in the presence of lateral electric fields due to a p-n junction. The effects of oxide fixed charge and interface state densities in the grown oxide layer on the p-n junction samples were considered in the proposed method. The extracted metallurgical and electrical junctions were compared to the apparent electrical junction obtained from SCM measurements. (C) 2002 American Institute of Physics.

Preliminary characterisation and extraction of anterior adhesive secretion in monogenean (platyhelminth) parasites

Secreted anterior adhesives, used for temporary attachment to epithelial surfaces of fishes (skin and gills) by some monogenean (platyhelminth) parasites have been partially characterised. Adhesive is composed of protein. Amino acid composition has been determined for seven monopisthocotylean monogeneans. Six of these belong to the Monocotylidae and one species, Entobdella soleae (van Beneden et Hesse, 1864) Johnston, 1929, is a member of the Capsalidae. Histochemistry shows that the adhesive does not contain polysaccharides, including acid mucins, or lipids. The adhesive before secretion and in its secreted form contains no dihydroxyphenylalanine (dopa). Secreted adhesive is highly insoluble, but has a soft consistency and is mechanically removable from glass surfaces. Generally there are high levels of glycine and alanine, low levels of tyrosine and methionine, and histidine is often absent. However, amino acid content varies between species, the biggest differences evident when the monocotylid monogeneans were compared with E. soleae. Monogenean adhesive shows similarity in amino acid profile with adhesives from starfish, limpets and barnacles. However, there are some differences in individual amino acids in the temporary adhesive secretions of, on the one hand, the monogeneans and, on the other hand, the starfish and limpets. These differences may reflect the fact that monogeneans, unlike starfish and barnacles, attach to living tissue (tissue adhesion). A method of extracting unsecreted adhesive was investigated for use in further characterisation studies on monogenean glues.