Fluorescence Characteristics of [(Benzoyloxy)methyl]anthracene Donor-Acceptor Systems.

A theoretical investigation on fluorescence properties of [(benzoyloxy)methyl]anthracene derivatives containing different groups (OCH3, CH3, H, CF3, F, CN, and NO2) as substituent on the phenyl ring is reported. Electron transfer rate constants for the molecules were calculated using Marcus theory. Theoretical electron transfer rate constants agreed with experimentally observed trend of fluorescence quenching. Large electron transfer rate constants were obtained for molecules containing strongly electron withdrawing groups as the substituent on the phenyl ring. Calculations were conducted at Hartree-Fock and density functional (HF/6-31G(d) and B3LYP/6-31G(d)) levels of theory. Density functional theory predicted spurious charge transfer excited states for molecules containing NO2, CN, and CF3 as the substituent on the phenyl ring.

Fluorescence quenching and bonding properties of some hydroxamic acid derivatives by iron(III) and manganese(II).

Spectrophotometric investigations of highly fluorescent metal chelating molecules are of relevance due to their potential application in novel, selective fluorescence-based sensors. Benzene and naphthalene chromophores are highly fluorescent while hydroxamic acids are widely used as ligands for complexation of transition metals. In order to develop fluorescence probes, several phenyl derivatives of N-phenylbenzohydroxamic acid and an aminodihydroxamic acid linked with a naphthalene chromophore were synthesized and their selective ionophoric properties towards iron(III) and manganese(II) ions were investigated using fluorescence and absorption spectroscopy. Both methods confirm the formation of 1:1 and 1:2 complexes for iron(III) and a 1:1 complex for manganese(II). The complex that is formed depends on the concentration of the ligand and pH of the medium. The amino dihydroxamic acid exhibits a prominent selectivity towards iron(III) with a two-step 1:1 and 1:2 quenching mechanism at pH 3 and towards manganese(II) with a 1:1 quenching mechanism at a probe concentration of 1 x 10(-5) mol dm(-3) at pH 9.5 The logarithm of overall formation constants of 1:1 and 1:2 complexes of iron(III) were estimated as 3.30 and 9.05, respectively.

Needlescopic thoracic sympathectomy: treatment for palmar hyperhidrosis.

BACKGROUND: Open thoracic sympathectomy has been the established option for patients with essential hyperhidrosis. Recently, video-assisted endoscopic sympathectomy has provided a simple, safe, reliable, and cost-effective alternative to the earlier technique. With advances in instrumentation, performing the procedure through 2-mm and 3-mm needlescopic ports is now possible. The authors evaluate the effectiveness of so-called needlescopic thoracic sympathectomy for the treatment of primary hyperhidrosis. METHODS: Thirty five consecutive patients with a mean age of 24 years, including 23 men and 12 women, underwent bilateral needlescopic thoracic sympathectomies at the National University Hospital of Singapore. RESULTS: The mean operative duration was 56 minutes, and the mean hospital stay was 1.2 days. In no patient did Horner's syndrome or significant pneumothorax develop. The rate of success, defined as completely dry hands, was 97%. Two patients had unilateral recurrences that responded well to repeat needlescopic sympathectomies. We performed a total of 72 sympathectomies. CONCLUSIONS: Our study demonstrates that the use of miniature port access sites produces excellent medical and cosmetic results and is associated with a short hospital stay and low risk of complications.

Ligand-binding radioassay for the antifolate compounds: application in patients receiving methotrexate.

The general principles of ligand-binding radioassays are reviewed and a specific noncompetitive system is described for the measurement of methotrexate (MTX) using dihydrofolate reductase as the binding determinant. This type of radioassay can also be exploited to measure any antifolate compound which binds to this enzyme even if [3H]MTX is used as the tracer. The radioassay has now been used to measure MTX in all types of body fluids, tissue extracts, and rbc lysates from patients receiving this drug.