Biomedical subjects

N L Wolfe

Publications and source records attributed to N L Wolfe.

12 recordsLinked to original sources

PubMed1987

Relationship between properties of a series of anilines and their transformation by bacteria.

The effect of compound structure on the microbial transformation of a series of substituted anilines was investigated. For the pure-culture and environmental water samples studied, the rate of transformation of the compounds decreased in the following order: aniline greater than 3-bromoaniline greater than 3-chloroaniline greater than 3-methylaniline greater than 3-methoxyaniline greater than 3-nitroaniline greater than 3-cyanoaniline. Second-order rate constants (kb) for each compound was calculated by using bacterial and compound concentrations measured as a function of time. The rate constants correlated with steric parameters. Water samples also were used in kinetic studies with three of the compounds (aniline, 3-chloroaniline, and 3-nitroaniline) to test the relationships with mixed bacterial populations. A simple linear regression of van der Waals radius of the substituent group with log kb gave correlation coefficients (r2) of 0.924 for the river isolate and 0.99 for the mixed populations. Analyses of pure-culture and mixed-population samples by thin-layer chromatography indicate that the primary products are catechols. This finding suggests that the transformation pathway involves oxidative deamination of the anilines.

Aniline Compounds↗

PubMed1986

Neurotropic melanoma of the lower lip.

The neurotropic melanoma is a rare and highly malignant variant of melanoma that possesses a biphasic neoplastic component. A lentigo maligna melanoma commonly precedes a downgrowth of spindle cells that exhibit fascicle formation and striking neurotropism. A strong predilection for occurrence on the lip has been indicated by published reports. Difficulties exist in the initial diagnosis of the tumor because of its biphasic growth pattern, while the biologic behavior of the tumor is that of multiple recurrences, perineural metastases with cranial neuropathies and intracranial disease, and regional and distant organ metastases. The clinical and histopathologic features of a neurotropic melanoma of the lip are shown, and a brief review of the histogenesis, treatment, and prognosis are presented.

Adult↗

PubMed1977

Photochemical transformation of the DDT and methoxychlor degradation products, DDE and DMDE, by sunlight.

DDE and DMDE, degradation products of the pesticides DDT and methoxychlor, rapidly undergo an unusual photoisomerization in solution when exposed to sunlight. The isomerization involves the exchange of a vinyl chlorine and an ortho aromatic hydrogen. Other photoproducts identified were corresponding benzophenones and 1,1-diaryl-2-chloroethylenes. Quantum yields for the reactions were measured and then used to compute sunlight photolysis half-lives for DMDE and DDE. Although both compounds absorb only the short-wavelength ultraviolet component of sunlight, their photolysis was found to be surprisingly rapid. During summer at latitude 40 degrees N, the photolysis half-lives near the surface of a water body are one hour and one day for dissolved DMDE and DDE, respectively. Photolysis of the DDE photoisomers is about an order of magnitude slower than that of DDE, suggesting that they may accumulate under environmental conditions. The DDE photoisomers photocyclize to form chlorinated dibenzofulvene and dichlorofluorenone. Neither DDE nor its photoisomers photoreact in solution to form PCB's. The environmental significance of these results is discussed, and its is suggested that the persistence of DDE in inland surface waters may be related to its tendency to sorb onto sediments and biota where not light is present.

Dichlorodiphenyl Dichloroethylene↗

PubMed1976