Identification Of Lead Research Articles

Design, synthesis and biological evaluation of pyridine-phenylpiperazines: A novel series of potent and selective α 1a-adrenergic receptor antagonist

Beginning from the screening hit and literature α 1-adrenergic compounds, a hybridized basic skeleton A was proposed as the pharmacophore for potent and selective α 1a-AR antagonists. Introduction of a hydroxy group to increase the flexibility afforded B which served as the screening model and resulted in the identification of the second-generation lead 1. Using the Topliss approach, a number of potent and selective α 1a-AR antagonists were discovered. In all cases, binding affinity and selectivity at the α 1a-AR of S-hydroxy enantiomers were higher than the R-hydroxy enantiomers. As compared to the des-hydroxy analogues, the S -hydroxy enantiomers displayed comparable potency and better selectivity at α 1a-AR. The S-hydroxy enantiomer 17 ( K i=0.79 nM; α 1b α 1a =800 ; α 1d α 1a =104 ) was slightly less potent but much more selective at α 1a-AR than tamsulosin ( K i=0.13 nM, α 1b α 1a =15 , α 1d α 1a =1.4 ). Compound 17 displayed higher selectivity in inhibiting rat prostate contraction over rat aorta contraction and also exhibited a higher degree of uroselectivity than tamsulosin in the anesthetized dog model.

Design, synthesis, and structure-activity relationships of phthalimide-phenylpiperazines: a novel series of potent and selective alpha(1)(a)-adrenergic receptor antagonists.

Beginning from the screening hit and literature alpha(1)-adrenergic compounds, a hybridized basic skeleton A was proposed as the pharmacophore for potent and selective alpha(1a)-AR antagonists. Introduction of a hydroxy group to increase the flexibility afforded B which served as the screening model and resulted in the identification of the second-generation lead 1. Using the Topliss approach, a number of potent and selective alpha(1a)-AR antagonists were discovered. In all cases, binding affinity and selectivity at the alpha(1a)-AR of S-hydroxy enantiomers were higher than those of the R-hydroxy enantiomers. As compared to the des-hydroxy analogues, the S-hydroxy enantiomers had slightly lower binding affinity at alpha(1a)-AR but gained more than 2-fold selectivity for alpha(1a)-AR over alpha(1b)-AR, and 2- to 6-fold selectivity for alpha(1a)-AR over alpha(1d)-AR. They also had less cross activities against a panel of 25-35 peripheral and CNS receptors. The S-hydroxy enantiomers 23 and 24 (K(i) = 0.29 nM, 0.33 nM; alpha(1b)/alpha(1a) >5690, >6060; alpha(1d)/alpha(1a) = 186, 158, respectively) were slightly less potent but much more selective at alpha(1a)-AR than tamsulosin (K(i) = 0.13 nM, alpha(1b)/alpha(1a) = 14.8, alpha(1d)/alpha(1a) = 1.4). In the functional assay, the S-hydroxy enantiomers 20, 23, and 24 were less potent than tamsulosin in inhibiting contractions of rat prostate tissue but more selective in the inhibition of tissue contractions of rat prostate versus rat aorta. Compound 24 was selected as the development candidate for the treatment of BPH.

Voltammetric Identification of Lead(II) and (IV) in Mediaeval Glazes in Abrasion-Modified Carbon Paste and Polymer Film Electrodes. Application to the Study of Alterations in Archaeological Ceramic

Direct identification of lead(II) and (IV) in glazed ceramics by cyclic voltammetry and differential pulse voltammetry is described. Characteristic cathodic and anodic profiles are obtained for microsample coatings in Paraloid B72-film electrodes immersed in NaCl and HAc/NaAc media. The electrochemical response of PbO, PbO2 and Pb3O4, and a series of test specimens of glaze is compared with that of microsamples extracted from the glaze of blue and white decorated ceramic produced in Manises (Spain) in the 15th century which have been buried in a damp place. Under abrasive conditions, striping peaks at –0.12 and –0.25 V (vs. SCE) appear for Pb(IV) centers and, at –0.55 and –0.75 V, for Pb(II) centers. The weathering process is accompanied by a significant decrease of the total lead content and an enhancement of the Pb(IV)/Pb(II) ratio suggesting that a significant fraction of Pb(II) ions is released. Electrochemical data are compared with those obtained from SEM/EDX.

Voltammetric Identification of Lead(II) and (IV) in Mediaeval Glazes in Abrasion-Modified Carbon Paste and Polymer Film Electrodes. Application to the Study of Alterations in Archaeological Ceramic

Voltammetric Identification of Lead(II) and (IV) in Mediaeval Glazes in Abrasion-Modified Carbon Paste and Polymer Film Electrodes. Application to the Study of Alterations in Archaeological Ceramic

Lead and copper contamination of soil from industrial activities and firing ranges.

Lead still remains one of the most thoroughly investigated heavy metals in the environment. Although the identification of lead in soil is a routine matter, its environmental consequence is still much debated because of its potential mobility. We have investigated lead- and copper-contaminated soil from two different areas. One was in an urban area, which formerly had a lead smelter within the city. The other a firing range, in which hundreds of thousands of rounds were fired into a very large mound known as a berm. Homogeneity tests, depth profiles, and Pb-Cu correlations are discussed.

Identification of lead(ii) sulfide and pararealgar on a 13th century manuscript by Raman microscopy

The in situ non-intrusive chemical analysis by Raman microscopy of a very rare, early 13th century, Byzantine/Syriac Gospel lectionary implies that the serious pigment blackening of many hues and affecting most of the illuminations is caused by the degradation of lead white to lead(II) sulfide, and that pararealgar (As 4 S 4 ) never previously identified on any manuscript was used throughout as a deep yellow pigment.

Identification of Lead and Other Elements in Ceramic Glazes and Housewares by 109Cd-Induced X-Ray Fluorescence Emission Spectrometry

Radioisotope x-ray fluorescence spectrometry was investigated as a potential screening method for Pb and other elements in housewares. Thirty-six commercial houseware items and 87 ceramic test tiles (85 fired with hobby glazes and 2 blank bisques) were examined qualitatively for the presence of Pb by using 109Cd-induced L x-ray fluorescence emission spectrometry. For the housewares, the technique provided fast, nondestructive analysis of areas with about 10 cm diameters (general regions) to about 4 mm diameters (isolated design regions). Pb was found in 25 of 28 ceramicware items, in all 8 other housewares, and in all the test-tile glazes above the limit of detection of 1 count per second (cps) for Pb L beta x-rays. For housewares, Pb identification did not always correspond to Pb leachability. For 68 test-tile glazes labeled as containing Pb (39 of which were also labeled 'dinnerware safe' or 'safe for food containers'), count rates ranged from 290 to 730 cps, whereas for the other 17 glazes labeled (with one exception) 'non-toxic,' much lower count rates (5-61 cps) were obtained. Other elements found in the housewares or test glazes were As, Au, Ca, Co, Cr, Cu, Fe, Mn, Nb, Ni, Rb, Sr, Y, Zn, and Zr.

Source identification of lead found in tissues of sailors from the Franklin Arctic Expedition of 1845

Atomic absorption analysis of recently discovered human remains from a 19 century British Arctic expedition indicates lead levels consistent with lead intoxication. Levels up to 30 times higher than those found in modern exposed individuals indicate that the effects of lead may have contributed to the loss of the entire expedition. Lead isotope ratio analysis by mass spectrometry demonstrates that the lead found in the human tissues originated from soldered food cans supplied to the expedition.

A single ECG lead in the serial monitoring of ischemic injury and necrosis in patients with acute anterior myocardial infarction: Comparison with 49-lead precordial maps and standard ECGs

To evaluate the single ECG lead with the maximal ST-segment elevation on admission as a modality suitable for monitoring ischemic injury and necrosis, the author correlated the single lead from 49-lead precordial maps and that from the corresponding standard ECGs with the ECG systems from which they derived. A total of 265 pairs of studies (14 per patient) from 20 patients with acute anterior myocardial infarction were used. Serial recordings were done on admission, at 12 predetermined time intervals during hospitalization, and at discharge. The amplitudes of ST-segment elevation, R waves, and Q waves of the single lead and all of the complexes of the corresponding precordial maps or standard ECGs were measured, using the same methodology. The single ECG lead correlated well with the precordial maps and the standard ECG. Although in serial studies the originally selected single lead was not the one displaying the maximal ST-segment elevation in 29% of the studies, it was always located on a locus immediately adjacent to the new lead in the grid recording the maximal ST. Changes in the precordial map or standard ECG were always detected by the corresponding single lead. The single lead from the standard ECG reflected changes in the precordial map, indicating that a precordial map is not necessary on admission for identification of the single lead. Correlations of R waves and Q waves from the single lead and the precordial map or the single lead and the standard ECG were not as good as the ones found for ST-segment elevation, although they provided monitoring of directional changes of the QRS complexes during hospitalization. Thus, a single lead from a precordial map or standard ECG is adequate for monitoring of the magnitude of ischemic injury in patients with acute anterior myocardial infarction. The single lead also provides some information as to the evolution of changes in the precordial QRS complexes associated with infarction and maintains its traditional role of providing surveillance for arrhythmias or conduction abnormalities.

Identification of Gasoline Lead in Children's Blood Using Isotopic Analysis

The isotopic composition and concentrations of lead were measured, using mass spectrometric analysis, in blood drawn from 14 young children who lived in Washington, D.C. The isotopic composition of lead in ambient air, which reflects the changing sources of gasoline lead, was also determined for the period of sampling. Blood lead concentrations ranged from 4.38 to 24.7 micrograms/100 g blood. Based on linear patterns that involved ratios of all four isotopes consistent with two component mixing, we estimate a minimum contribution of recent gasoline lead ranging from 0 to 57% of the blood lead burden.

Identification of lead in Asian cosmetics—A test for use by health visitors

Advice given to Asian mothers by the Department of Trade and Industry on testing forlead in traditional cosmetics is proving misleading and is giving rise to concern. No satisfactory test for lead which can be carried out by the mothers currently exists. However, it is recommended that the “water flotation test” is modified by using liquid paraffin and redefining the criteria applied to the results. It is further suggested that testing for lead in these cosmetic materials is performed more definitively by community health visitors who, with minimal instruction, can perform the simple analyses described in detail herein. In conclusion it is recommended that the emphasis should be more firmly based on education of the Asian mother away from use of surma instead of devising methods for testing for lead which may be misleading and, in the long term, are impractical.

Mass spectrometric identification of unusual lead and tin alkyls produced by the electrochemical reduction of methyl-ethyl ketone at lead/tin alloys

The reduction of methylethylketone in hydroalcoholic acid solutions at Pb/Sn alloy cathods have shown that organoderivatives of both metals are formed in not negligible yields. Mass spectrometric analysis of catholites could identify, other than the expected tetraalkyl derivatives, polyalkylated metallic chains comprising SnPb intermetallic bonds.

鉛中毒シロネズミの腎における鉛の貯留について : 組織学的ならびに電子顕微鏡学的考察

Deposition of lead in the kidney of rats suffered from lead poisoning were examined by the use of both light and electron microscopes. Chronic lead poisoning of rats was attained by 13 successive intraperitoneal injections with 1 ml of 1% lead acetate solution once in two weeks over a period of 26 weeks. Subacute lead poisoning of rats was attained by 3 intraperitoneal injections with 1 ml of 5% lead acetate solution once in two weeks over a period of 6 weeks. Light microscopic observations on the kidneys from chronically lead-poisoned rats showed that proximal tubules were atrophic with a concomitant increase and swelling of the interstitial tissue, or dilatated with flattened and atrophic epithelia. Most glomeruli appeared intact. The presence of dense concretions and nuclear inclusion bodies in the epithelial cells of the proximal tubules was dominant in this case. The dense concretions were different from the inclusion bodies, spherical or ovoid in shape, and varied in size, of which diameter ranged up to 50 μm. In subacutely lead poisoned rats, the concretions usually appeared in the lumen of the proximal tubule. A hydrogen sulfide test for identification of lead by Iwahashi strongly suggested that the concretions contained lead. From the electron microscopic observations, the concretions were shown to be the complexes of needle-like components less than 100 A in width and electron-dense material. The needle-like component were usually organized into concentric lamellae, on which the dense material deposited. The concretions were never found in nuclei. Besides, the concretions were clearly surrounded by a single membrane. Inclusion bodies were found in the enlarged nuclei of proximal tubule cells as complexes of filament of 70-170 A in width and electron-dense substance. From these fidings, it was suggested that exogenous lead deposited in the concretions enclosed by the limiting membranes which may be a form of lysosome.

The control of geometric form in lead chloride crystals for the production of characteristic profile angles. Application to the identification of lead

By varying the molarity of hydrochloric acid, it has been found possible to obtain PbCl2 in different geometric forms. The profile angles may serve as constants for the identification of lead.

Chemical analysis on the microgram scale. II

The separation and identification of lead, mercurous mercury, silver and tungstate on the microgram scale are described, these ions being treated as Group II of a non-H2S schematic analysis.

The Identification and Localization of Lead in Bone Tissue

The Identification and Localization of Lead in Bone Tissue