Comparison of the third molar maturity index (I3M) between left and right lower third molars to assess the age of majority: a multi-ethnic study sample.

The diagnostic accuracy of the I3M to assess the legal age of 18 years has already been tested in several specific-population samples. The left lower third molar has been extensively used for discriminating between minors and adults. This research aimed to compare the usefulness of lower third molar maturity indexes, from both left and right side (I3ML and I3MR), in samples originating from four distinct continents in order to examine possible differences in their accuracy values. For this purpose, a sample of 10,181 orthopantomograms (OPGs), from Europe, Africa, Asia and America, was analysed and previously scored in other studies. The samples included healthy subjects with no systemic disorders with both third molars and clear depicted root apices. Wilcoxon Signed Rank test for left and right asymmetry did not show any significant differences. Data about sensitivity, specificity, predictive values, likelihood ratio and accuracy were pooled together and showed similar results for I3ML and I3MR, respectively. In addition, all these quantities were high when only the I3MR was considered to discriminate between adults and minors. The present referable database was the first to pool third molar measurements using panoramic radiographs of subjects coming from different continents. The results highlighted that both I3ML and I3MR are reliable indicators for assessing the legal age of 18 years old in those jurisdictions where this legal threshold has been set as the age of majority.

The plecomacrolide vacuolar-ATPase inhibitor bafilomycin, alters insulin signaling in MIN6 beta-cells.

Inhibition of endosomal acidification disturbs insulin signaling in both liver and adipose cells. In this study we used MIN6 beta cells to determine whether bafilomycin, a potent inhibitor of the proton-translocating vacuolar ATPase, disrupts insulin signaling in islet beta cells. Pretreatment of MIN6 cells with varying concentrations of bafilomycin according to a time course revealed concentration and time-dependent changes in phosphorylation of insulin receptor signaling components. Increased phosphorylation of insulin receptor (IR), IRS2 and Akt was prolonged at low bafilomycin concentrations (10 and 50 nmol/L), whereas at high concentrations (100 and 200 nmol/L) phosphorylation rapidly returned to basal levels or below. Akt activation was demonstrated by transient increases in phosphorylation of BAD, cytoplasmic retention of FoxO1 and increased preproinsulin mRNA. Bcl2 expression was also transiently increased but reduced after 30 min exposure to bafilomycin, and this coincided with reduced cell viability. Thus, in beta cells inhibition of endosomal acidification by low concentrations of bafilomycin transiently increases insulin signaling, whereas high concentrations promote cell death. Bafilomycin and other agents that interfere with insulin signaling may contribute to diabetes development through disturbing homeostatic control of beta cell growth.

Transplacental exposure to bafilomycin disrupts pancreatic islet organogenesis and accelerates diabetes onset in NOD mice.

Bafilomycin, a plecomacrolide produced by plant-pathogenic Streptomyces, contaminates tuberous vegetables and has adverse effects on beta cells in adult mice. We therefore determined whether dietary bafilomycin influenced the progression of diabetes in the non-obese diabetic (NOD) mouse model of autoimmune Type 1 diabetes. Parent NOD mice were fed sub-toxic doses of bafilomycin in drinking water from conception until weaning, or various times after birth and blood glucose was monitored in the offspring. Pancreatic islets in neonatal offspring were examined histologically by quantitative morphometry and islet cell apoptosis was estimated by TUNEL assay. Exposure in utero to bafilomycin but not after birth significantly accelerated onset and increased the frequency of diabetes. In exposed mice, pancreatic islet organogenesis was disrupted, characterized by a striking increase in beta-cell mass and a shift in timing of the normal wave of neonatal islet cell apoptosis from 2 weeks to 4 weeks of age. We postulate that accelerated onset and increased incidence of diabetes later in life result from disruption of the normal turnover of beta cells in the neonatal pancreas. Since bafilomycin and related plecomacrolides contaminate Streptomyces-infected vegetables, dietary exposure during pregnancy could be an important and previously unsuspected environmental component of human Type 1 diabetes.

Dietary microbial toxins and type 1 diabetes.

Toxins may promote type 1 diabetes by modifying or damaging the beta cell causing release of autoantigens. Streptomyces is a common soil bacterium that produces many toxic compounds. Some Streptomyces can infect vegetables, raising the possibility of dietary exposure to toxins. We aimed to identify toxins that erode cellular proton gradients in extracts of Streptomyces and infested vegetables and to establish the effect of low doses of these toxins on pancreatic islets in mice. The vacuolar ATPase inhibitors, bafilomycin and concanamycin, and the ionophore, nigericin, were identified in extracts from 4 of 13 Streptomyces isolated from infested potatoes and in potatoes themselves. Injection of bafilomycin A1 into mice impaired glucose tolerance, reduced islet size, and decreased relative beta cell mass. Thus, exposure to small quantities of bafilomycin in the diet may contribute to the cause of type 1 diabetes.

Analysis of 2beta-carbomethoxy-3beta-(4-fluorophenyl)-N-(3-iodo-E-allyl)nortropane in rat plasma. II. Pharmacokinetic profile in male and female Sprague-Dawley rats evaluated by capillary electrophoresis.

This paper describes a pharmacokinetic study performed in Sprague-Dawley rats after i.v. administration of a single 6-mg/kg dose of 2beta-carbomethoxy-3beta-(4-fluorophenyl)-N-(3-iodo-E-allyl)nortropane (Altropane). Plasma samples were collected from the retro-orbital sinus at times up to 3 h after drug administration, extracted by solid-phase extraction, and the drug levels determined by capillary electrophoresis (CE). Pharmacokinetic parameters were determined by a standard noncompartmental model using WinNonlin version 1.5. The maximum plasma concentrations, clearances of the drug, and areas under the curve for male and female rats were 5.74 and 7.26 microg/ml, 135.7 and 98.5 ml/kg x min, and 44.23 and 60.92 microg x min/ml, respectively. The drug was cleared very rapidly from the systemic circulation, with a terminal t(1/2) of 7 to 10 min and a mean residence time of about 11 min for both sexes. The volume of distribution was approximately 1 l/kg. No metabolites were detected when the samples were analyzed individually. However, after samples were pooled and concentrated, traces of two unknown peaks that may represent metabolites were detected in concentrates from the last two timepoints. Part I of this work [J. Chromatogr. A, 895 (2000) 87] describes validation of CE methods for the analysis of aqueous and plasma samples of Altropane, including its solid-phase extraction from rat plasma.

Characterization and analysis of biphalin: an opioid peptide with a palindromic sequence.

Among the many opioid peptides developed to date as nonaddictive analgesics, biphalin has exhibited extraordinary high potency and many other desirable characteristics. Biphalin is an octapeptide consisting of two monomers of a modified enkephalin, attached via a hydrazine bridge, and with the amino acids assembled in a palindromic sequence. Its structure is (Tyr-D-Ala-Gly-Phe-NH-)-2. However, this unique peptide, like any other synthetic peptide, needs strict quality control because of certain drawbacks associated with peptide synthesis. This paper discusses our approaches to characterizing and analyzing biphalin. Many techniques were used, including elemental analysis, amino acid analysis, amino acid sequence analysis (AASA), mass spectrometry (MS), 1H-NMR, 1H-correlated spectroscopy (COSY)-NMR, high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE). Electrospray ionization (ESI) mass spectrometry, which included both ESI-MS and ESI-MS/MS, was performed to confirm the full sequence because AASA results alone verified only the monomer sequence, and not the full sequence. Although the 1H-NMR results led to a preliminary assignment of many protons, the 1H COSY-NMR results allowed for unequivocal assignment of almost all protons. Peptide purity was determined using two techniques, reversed-phase HPLC and CE. The counter-ion of the peptide, trifluoroacetic acid, was determined by CE, using an indirect detection method developed previously in our laboratory. This paper illustrates successful application of nonconventional techniques to characterize and analyze a structurally modified peptide, biphalin, when standard techniques for peptide analysis are inadequate.

Analysis of 2beta-carbomethoxy-3beta-(4-fluorophenyl)-N-(3-iodo-E-allyl)nortropane in rat plasma. I. Method development and validation by capillary electrophoresis.

Altropane, 2beta-carbomethoxy-3beta-(4-fluorophenyl)-N-(3-iodo-E-allyl)nor tropane, is an imaging agent that was developed recently for early detection of Parkinson's disease. Its promise as a useful radiopharmaceutical for single-photon emission computed tomography or positron emission tomography imaging of the brain has been well demonstrated, and it is currently undergoing clinical trials. This paper presents methods development and validation of capillary electrophoresis (CE) techniques to analyze Altropane in aqueous environments as well as in rat plasma, using an internal standard, nicotinamide. N-Allylaltropane, 2beta-carbomethoxy-3beta-(4-fluorophenyl)-N-allylnortropane, which is a known degradation product of the Altropane precursor (tributyltinaltropane), was used to verify the method's specificity. A solid-phase extraction method for extraction of Altropane from rat plasma is also described. The results presented in this paper demonstrate the applicability of CE methods to study the pharmacokinetic properties of Altropane in animal models. The results of the pharmacokinetic study will be published later, as Part II.

Capillary electrophoretic determination of acetic acid and trifluoroacetic acid in synthetic peptide samples.

Synthetic peptide samples may contain counter-ions such as acetate or trifluoroacetate as a result of their method of preparation. Furthermore, because acetic acid (HOAc) and trifluoroacetic acid (TFA) are frequently used reagents in peptide synthesis, these acids may be found in synthetic peptide samples as impurities. This paper describes a method validation to determine HOAc and TFA in synthetic peptide samples by capillary electrophoresis (CE) using an internal standard (I.S.) with indirect UV detection. Typical analytical parameters such as precision, linearity, accuracy, specificity, limit of detection and ruggedness were evaluated during the validation. In addition, the contents of HOAc and TFA in two synthetic opioid peptide samples, TIPP[psi] and Orphanin FQ, were determined using the validated method. A unique feature of the method is that it offers determination of both acids in a single assay using a common I.S. The method is very efficient because of relatively short electrophoretic migration times (typically 2 to 8 min) for the acids investigated. This paper also discusses the factors that affect precision in a CE assay.

Precision in capillary electrophoresis with respect to quantitative analysis of suramin.

Suramin is an important anti-tumor and anti-viral chemotherapeutic agent. We have previously presented a capillary electrophoresis (CE) method for its quantitative analysis, where its quantitation was linear over three orders of magnitude, with good precision (1.8%) and accuracy. The constantly varying electroosmotic properties of the capillary due to various causes such as analyte adsorption to the inner wall, affect the migration times of analytes during consecutive electrophoresis runs. This results in progressive changes in analyte peak areas, causing less desirable or unacceptable CE assay precision. This paper illustrates a strategy to overcome the problem of assay reproducibility by using an internal standard whose migration time is short and close to that of the analyte so that the relative change of migration time is minimized. Assay precisions as good as 0.3% were observed in these experiments. These results are in agreement with the theoretical basis of experimental capillary electrophoresis.

Application of HPLC and CZE to the analysis of polyoxometalates.

Polyoxometalates (POM) are polymers of transition metal oxides. They are widely used as analytical reagents and reaction catalysts. Some have anti-viral properties and are being investigated as anti-HIV agents. Due to solubility and stability limitations, separation methods for POM are rare in the literatures. This paper presents a HPLC and a CZE method for the analysis of sodium tungstate, its equilibrium products and isopolyanions. The methods are simple and sensitive, and can be used to monitor the purity, stability and solution equilibria of POM.

Quantitative capillary electrophoresis and its application to the polyanionic quinobene.

Factors affecting the accuracy of capillary electrophoresis (CE) assays in general are discussed. Methods to improve the reproducibility and reliability of these assays are suggested. The improvements are demonstrated by developed CE assays for quinobene and suramin. The assays were reproducible (RSD < 2%), accurate (error < 2%), and linear over a concentration range of 1-800 micrograms ml-1 (r2 = 0.999).

Liquid chromatography and capillary electrophoresis analysis of polyanionic quinobene.

Quinobene is the tetrasodium salt of an organic tetrasulphonic acid. Its unusual solubility characteristics makes the development of LC analysis difficult. However, a specific, precise and accurate LC assay was eventually achieved for quinobene. The assay required gradient elution and was not efficient for quinobene with respect to plate number. As an alternative, a capillary electrophoresis (CE) assay was also developed for quinobene. The CE assay was comparable to the LC assay in precision and accuracy. It was unaffected by the unusual solubility characteristics of quinobene and was more specific, efficient and rugged than the LC assay.

Capillary electrophoresis analysis of concanavalin A and its succinyl derivative.

A high-performance capillary electrophoresis (CE) system has been developed for concanavalin A (Con A) and its succinyl derivative (SCA). Under the CE system, the tetramer, trimer, dimer, monomer and protein fragments of CA were separated in less than 50 min. SCA was resolved into more than 10 components which were believed to be isomeric succinyl derivatives of Con A. The CE system is a simple and sensitive analytical technique to profile the composition of Con A and SCA preparations. The minimum concentration of Con A in water detectable by the CE system is 1 microgram ml-1.