Malignant melanoma in a child with oculocutaneous albinism.

Malignant melanoma is extremely rare in patients with albinism. To date, in the English language literature, there have been only sixteen documented cases of malignant melanoma in albino patients. These cases include thirteen cutaneous, one oral, one ocular, and one anal; only one of these was in a child. Here, we present the case of the youngest known albino patient to have cutaneous malignant melanoma.

Chemical synthesis and surface activity of lung surfactant phospholipid analogs. II. Racemic N-substituted diether phosphonolipids.

A series of racemic 16:0 disaturated N-substituted diether phosphonolipid analogs of glycerophospholipids have been synthesized and purified. Isosteric methylene substitution at three of the four ester sites (carboxyl, phosphate) of conventional glycerophospholipids enhanced the hydrophobicity of analog compounds compared with dipalmitoyl phosphatidylcholine (DPPC), the major glycerophospholipid component of lung surfactant. Further substitutions at the nitrogen headgroup also contributed to hydrophobicity/hydrophilicity characteristics, as well as allowing graded variations in headgroup size among the members of the diether phosphonolipid analog series. Interfacial property studies showed that these compounds had significant differences in surface activity characteristics compared with DPPC, including increased adsorption and respreading facility, plus an enhanced ability to generate low surface tension (less than 1 to 4 mN/m) on an oscillating bubble apparatus at 37 degrees C. In addition, pressure-volume mechanical studies in surfactant-deficient excised rat lungs showed that the diether phosphonate analog of DPPC could partially restore pressure-volume characteristics toward normal, both as a pure component and in binary mixtures with palmitoyl-oleoyl phosphatidylglycerol. These findings suggest that selected analog compounds, synthesized with relatively small structural modifications from biologic glycerophospholipids, may have eventual applications as components of synthetic exogenous lung surfactants. Of more immediate importance, analog molecules with defined structural variations are convenient molecular probes for developing structure-surface activity correlates for phospholipid-like surfactants and for investigating the specificity of interactions between glycerophospholipids and other compounds such as proteins.

Chemical synthesis and surface activity of lung surfactant phospholipid analogs. III. Chiral N-substituted ether-amide phosphonolipids.

A homologous series of chiral (R) ether-amide phosphonolipid analogs of naturally occurring (R) glycerophospholipids were synthesized and characterized for their interfacial behaviors. The phosphonolipids possess isoteric ether, amide, and phosphonate functions at positions corresponding to the sn-1, sn-2, and sn-3 ester functions, respectively, of naturally occurring glycerophospholipids. All compounds were synthesized with disaturated C16:0 alkyl/acyl moieties to give structural analogy with dipalmitoyl phosphatidylcholine (DPPC), the major glycerophospholipid component of lung surfactant. Further substitutions at the headgroup nitrogen were also used to generate differences in headgroup size and polarity in the synthetic compounds. The surface activity of the ether-amide phospholipids was investigated in terms of adsorption to the air-water interface, together with studies of dynamic respreading after monolayer collapse and surface tension lowering in dynamically compressed spread films and dispersions. Results showed that several ether-amide phosphonolipids had more rapid adsorption and improved dynamic respreading behavior compared to DPPC, plus the ability to lower surface tension into the range of less than 1 to 4 mN/m in spread films and in dispersions under dynamic conditions. In combination with a series of diether phosphonolipids synthetized in a companion study [1], these ether-amide compounds are useful in the development of molecular structure-surface activity correlates for lung surfactant-related materials, and should assist in investigating the specificity of interactions between phospholipids and other pulmonary biological molecules.

Preparative-scale high-performance liquid chromatographic separation and purification of 3'-azido-3'-deoxythymidine-5'-phosphate.

Crude 3'-azido-3'-deoxythymidine-5'-phosphate (AZT-P), obtained from direct phosphorylation of 3'-azido-3'-deoxythymidine (azidothymidine, AZT), was separated and purified by isocratic preparative high-performance liquid chromatography. The components in a 2.5-g load of crude AZT-P, obtained from work-up of the phosphorylation reaction, were separated in 50 min to give 1.8 g of 99.5% pure AZT-P. AZT-P was analyzed by high-performance liquid chromatography and by high-resolution nuclear magnetic resonance (1H, 13C, 31P) spectroscopy. The practical and rapid preparative chromatographic method is being applied to the purification of AZT-P and other antiretroviral dideoxynucleotides, used as intermediates in the synthesis of target-directed experimental drugs for the treatment of AIDS.

Anticonvulsant activities of phenyl-substituted bicyclic 2,4-oxazolidinediones and monocyclic models. Comparison with binding to the neuronal voltage-dependent sodium channel.

8,9-Dioxo-6-phenyl-1-aza-7-oxabicyclo[4.2.1]nonane (1) and 9,10-dioxo-7-phenyl-1-aza-8-oxabicyclo[5.2.1]decane (2), examples of anti-Bredt bicyclic 2,4-oxazolidinediones, were investigated as anticonvulsants in mice. Compound 2 was the more potent (anti-MES ED50 = 66 mg/kg), and its in vivo anti-MES effect was consistent with its in vitro potency of binding to the voltage-sensitive sodium channel (IC50 = 160 microM for the inhibition of binding of [3H]BTX-B), suggesting that 2 may be a new class I anticonvulsant. Several partial structures of 2, either monocyclic lactams or monocyclic 2,4-oxazolidinediones, were also evaluated in these assays, but no correlation was observed between sodium channel binding and anti-MES effects. A significant finding was that monocyclic 5-alkyl-5-phenyl-2,4-oxazolidinediones provided relatively potent, nontoxic, broad-spectrum anticonvulsants.