Synthesis of a new fluorescent probe specific for catechols

[reaction: see text] The synthesis of a new fluorescent probe, specific for the catechol moiety, has been conducted by preparation of alpha,alpha-dibromomalonamides containing an appropriate fluorophore. N,N'-Bis-anthracen-9-ylmethyl-2,2-dibromomalonamide reacted with various catechols in the presence of cesium carbonate to generate highly fluorescent derivatives.     

Enzymatic synthesis of chiral organophosphothioates from prochiral precursors

The phosphotriesterase from Pseudomonas diminuta has been shown to selectively cleave the pro-R p-nitrophenolate substituent from bis-p-nitrophenyl alkyl phosphothioate esters. When the alkyl substituent is methyl, ethyl, or isopropyl the enantiomeric excess of the product is >/=99%. Manipulation of the active site through mutagenesis has enabled the preparation of protein variants that preferentially hydrolyze the pro-S substituent of the target substrates. This methodology thus permits the preparation of chiral products from prochiral precursors.     

Length scales of acceleration for locally isotropic turbulence

Length scales are determined that govern the behavior at small separations of the correlations of fluid-particle acceleration, viscous force, and pressure gradient. The length scales and an associated universal constant are quantified on the basis of published data. The length scale governing pressure spectra at high wave numbers is discussed. Fluid-particle acceleration correlation is governed by two length scales: one arises from the pressure gradient, the other from the viscous force.     

The Monodelphis melanoma model: initial report on large ultraviolet A exposures of suckling young

The objective of this study was to determine whether exposure of early suckling young of the opossum Monodelphis domestica to ultraviolet A (UVA) radiation (320-400 nm) can lead to the development of melanocytic lesions similar to those induced after exposure to ultraviolet B (UVB) radiation (280-320 nm) to total doses as low as 380 J/m2. A total of 576 sucklings received nine exposures of 0.6, 2.6 or 15.5 kJ/m2 per dose (total doses approximately 6, 23 and 140 kJ/m2, respectively) from a Blak Ray lamp source with a narrow range emission at 365 nm. A further 280 sucklings were exposed in the same way to doses of 2.6 kJ/m2 per dose (total approximately 23 kJ/m2) broad-band UVA with visible wavelengths from a Dermalight lamp. Frequency of litter loss following all of the UVA-exposure protocols was similar to that within the same stocks in the colony at large. Only one of the 856 UVA-exposed individuals possessed a melanocytic lesion at the 5 month assessment point. No radiation-induced lesions of any type were evident on the skin of the other animals exposed as sucklings. The affected male was from a group of 70 individuals exposed to the highest total dose (140 kJ/m2) from the Blak Ray light source. The melanocytic hyperplasia was provisionally identified as a potential melanoma but it slowly regressed as the animal aged. We conclude that in the opossum suckling exposure system, the potency of UVA for melanoma induction is extremely low compared with that of UVB. Possible explanations, amenable to further investigations, are given for the low UVA sensitivity of the suckling model compared to the adult exposure model of Ley (Ley, R. D. [1997] Cancer Res. 57, 3682-3684).     

Design and development of a fiber-optic immunosensor utilizing near-infrared fluorophores

The design and application of a fluorescent fiber-optic immunosensor (FFOI) are reported. The FFOI is utilized for the detection of antibody/antigen binding within the near-infrared (NIR) spectral region. The technique is developed through the combined use of fiber-optic, semiconductor laser-excitation, fluorescence detection, NIR dye, and immunochemical techniques. The antibody is immobilized on the FFOI and utilized as a recognition component for trace amounts of specific antigen. The FFOI is constructed to utilize an antibody sandwich technique. The assay involves the immobilization of the capture antibody on the sensing tip of the FFOI followed by the exposure of the immobilized sensing tip to the antigen. The antigen-coated FFOI is then introduced to a second antibody previously labeled with the NIR dye. Typical measurements are performed in about 15 min. A semiconductor laser provides the excitation (780 nm) of the immune complex. The resulting emission is detected by a silicon photodiode detector (820 nm). The intensity of the resulting fluorescence is directly proportional to the concentration of the antigen. The sensitivity of the analysis reaches 10 ng/ml and the response time is 10–15 min.     

Caps and codes

The packing problem in the theory of caps is that of finding, or at least bounding, the size m(r, q) of an ovaloid (cap of largest size) in the projective space S_r,q of dimension r over a field of q elements. This problem and that of constructing and classifying ovaloids are approached by consideration of certain codes associated with caps. Improved general upper bounds on m(r, q) are found, which give m(5, 3)?56 as a particular case. A 56-cap in S_5,3 is constructed via its code and its uniqueness as an ovaloid is demonstrated.