Bernard S. Green

Protective effect of povidone-iodine ointment against skin lesions induced by sulphur and nitrogen mustards and by non-mustard vesicants.

Abstract Mustard gas (sulphur mustard, SM) is a powerful vesicant employed as a chemical weapon. The present study demonstrates the effect of povidone iodine (PI) ointment against skin toxicity caused by SM. Gross and histopathological examinations showed that application of PI up to 20 min following exposure to the vesicant resulted in marked skin protection. The shorter the interval between exposure and treatment the better was the protection achieved. PI was also effective against other mustards such as carboxybutyl chloroethyl sulphide (CBCS) and mechlorethamine. The fact that PI protected the skin against agents which cannot be oxidized such as iodoacetic acid, divinylsulphone and cantharidine showed that the antidotal effect of PI was unrelated to oxidation of the nitrogen and sulphur atoms of the mustards. PI ointment is proposed as an efficient protective agent against skin toxicity caused by mustards and other alkylators.

Chiral discrimination using an immunosensor

Based on the stereoselectivity of immunoglobulins, we have developed a new chiral sensor for the detection of low-molecular-weight analytes. Using surface plasmon resonance detection, enantiomers of free, underivatized α-amino acids can be monitored in a competitive assay by their interaction with antibodies specific for the chiral center of this class of substances. The sensitivity to the minor enantiomer in nonracemic mixtures exceeds currently available methods; therefore, such immunosensors can readily detect traces of enantiomeric impurities and are attractive for a range of applications in science and industry.

Lamellar Twinning Explains the Nearly Racemic Composition of Chiral, Single Crystals of Hexahelicene

Solvent etching of single crystals of hexahelicene grown from a racemic solution reveals an unusual layer-like pattern in which pure (+)- and pure (–)-layers alternate through the crystal; this arrangement results in a nearly racemic composition although the crystal is ostensibly chiral, space group P212121. Etched crystals of enantiomerically pure hexahelicene display no such pattern. The two kinds of crystal are indistinguishable by x-ray diffraction.

The use of mid-points or average NMR chemical shifts in stereochemical assignments

Abstract A comparison of the mid-points or average chemical shifts of mirror-symmetrical spin patterns in the NMR spectra of structural isomers can be used in a straightforward manner to obtain stereochemical information. This result is anticipated from analysis of substituent contributions to chemical shifts and has been observed in a variety of chemical systems, especially cyclobutane derivatives, which comprise a group of compounds for which appreciable data is available and whose structure assignments have often entailed difficulty and even controversy. The method of mid-point comparison may also be useful for conformational analysis.

Differences in the biochemical properties of esterolytic antibodies correlate with structural diversity

A prerequisite to the design and engineering of catalytic antibodies is the knowledge of their structure and in particular which residues are involved in binding and catalysis. We compared the structure and catalytic properties of a series of six monoclonal antibodies which were all raised against a p-nitrophenyl (PNP) phosphonate and which catalyze the hydrolysis of p-nitrophenyl esters. Three of the antibodies (Group I) have similar light and heavy chain variable regions. The other three antibodies have similar VL regions of which two (Group II) have VH regions from the MOPC21 gene family and the remaining one (Group III) a VH from the MC101 gene family making a total of three different groups based on their V region sequences. The structural division into groups is paralleled by the differences in binding constants to hapten analogs, substrate specificity and the susceptibility of the catalytic activity of the antibodies to chemical modification of tryptophan and arginine residues. The relative binding of a transition state analog to the binding of substrate is much higher for the Group I antibodies than for the other groups. Only the Group I antibodies can catalyze the hydrolysis of a carbonate substrate. However all of the antibodies lose catalytic activity upon specific tyrosine modification which highlights the importance of tyrosine in the active site of the antibodies. Thus, antibodies raised against a single hapten can give antibodies with different structures, and correspondingly different specificities and catalytic properties.

Immobilization of antibodies onto glass wool.

The immobilization of antibodies onto solid phases in an efficient and activity-retaining form is an important goal for both research and industry. Methods have been developed for the site-directed attachment of antibodies to agarose by oxidation of the carbohydrate moieties in their Fc region. Similar attachment to silianized supports have not been as successful. Here we describe a novel combination protocol for the site-directed attachment of periodate oxidized, goat polyclonal antibodies to glass wool fibers activated with 3-aminopropyltriethoxysilane. The study demonstrates that this procedure results in effective immobilization of polyclonal antibodies that retain their antigen-binding capacity. This protocol should prove useful in the development of more efficient and effective glass-based immunosupports.

Catalytic monoclonal antibodies: tailor-made, enzyme-like catalysts for chemical reactions

Abstract During the past two years, monoclonal antibodies with enzyme-like catalytic properties have been successfully raised. They catalyse a variety of reactions (hydrolysis of esters, amides and carbonates; bimolecular reactions; cyclization reactions; elimination reactions; asymmetric synthesis) with rate enhancements of up to 6 × 10 6 fold and high specificity, including enantiomer specificity. Hybrid antibodies containing covalently-linked catalytic or probe groups have been prepared and antibody-mediated peptide hydrolysis catalysed by metal ion complexes has been reported. Catalytic monoclonal antibodies could have wide-ranging, exciting applications in biology, medicine, chemistry and biotechnology.

Reactions in Chiral Crystals. Principles Governing Asymmetric Synthesis via Topochemically Controlled Solid-State Photo-Dimerization

Abstract The chemical and crystallographic requirements for utilizing solid-state photodimertization reactions in the medium of chiral single crystals to realize asymmetric syntheses have been considered. Asymmetric syntheses are possible from a variety of reactions in the monocomponent or two-component crystals which have been considered and in favorable cases quantitative optical yields are anticipated. These principles can be extended to other reactions including the formation of chiral cyclobutane photopolymers.

Protective effect of povidone iodine ointment against skin lesions induced by chemical and thermal stimuli.

Mustard gas (sulfur mustard, HD) is a powerful vesicant employed as a chemical weapon. The present study demonstrates the effect of povidone iodine (PI) ointment against skin toxicity caused by HD. Gross and histopathological examinations showed that application of PI 20 min or less following exposure to the vesicant resulted in marked skin protection. The shorter, interval between exposure and treatment, the better was the protection achieved. Povidone iodine was also effective against other mustards, such as carboxybutylchloroethyl sulfide (CBCS) and mechlorethamine. The fact that PI protected the skin against agents that cannot be oxidized, such as iodoacetic acid, divinylsulfone and cantharidine, indicated that the antidotal effect of PI was unrelated to oxidation of the nitrogen and sulfur atoms of the mustards. Furthermore, NMR spectroscopy of CBCS treated with iodine did not show oxidation of the sulfur atom. Clinical experience with patients after accidential heat burns (mostly of grade I) has shown that topical application of PI ointment immediately after the stimulus significantly reduced, and often prevented, skin lesions. Apart from being a safe and widely used disinfectant, PI ointment is recommended as an efficient protective agent against skin toxicity caused by hazardous chemicals and by heat stimuli. Copyright

Excimer emission and photodimerization in a crystalline stilbene

Abstract Crystalline 2,4-dichloro- trans -stilbene (II) displays excimer emission and undergoes photoreaction to yield the mirror-symmetric dimer 1, cis -2-di(2, 4-dichlorophenyl)- trans -3, tarans -4-diphenlcyclobutane (III). In solution, under a variety of conditions. II shows only monomer emission and yields, in addition to III, the centric photodimer 1, trans -3-di(2,4-dichlorophenyl)- cis -2, trans -4-diphenylcyclcbutane (IV) and cis -monomer.