Histologic features seen in changing nevi after therapy with an 810 nm pulsed diode laser for hair removal in patients with dysplastic nevi.

BACKGROUND: The majority of lasers used for hair removal target melanin as the chromophore. In contrast with other cutaneous applications of lasers, lasers used for hair removal must generate a limited, controlled degree of thermal damage to permanently remove hairs. AIM: To remove excess back hair from two male patients, one with a history of multiple nevi, and prior biopsies showing features of dysplastic nevi, and the other with large nevi greater than 6 mm in diameter and a family history of malignant melanoma. METHODS: Both patients received monthly treatments with an 810 nm, pulsed, high-power diode laser using a fluence of 20 J/cm2 and 25-30 J/cm2, respectively, and a pulse duration of 30 ms. RESULTS: Both patients presented 1 month after their last treatment with changing nevi within the treatment areas. Neither patient had clinical inflammation or other alterations suggestive of change in the nevi related to treatment. Thus, the nevi were excised with no mention of the previous laser treatment. The histologic features in all nevi were similar. There was subepidermal blister formation with elongation and disruption of nevus cells. There was homogenization of the collagen within the papillary dermis in all lesions. Only small foci of nevus cells could be identified in the dermis in some of the biopsy specimens. In these biopsy specimens, the dermal stromal matrix homogenization extended into the reticular dermis. CONCLUSIONS: Laser targeting of nevus cells and surrounding structures may produce clinically atypical nevi in areas previously treated for hair removal. This should be kept in mind, especially in patients with a history of dysplastic nevi or with a personal or family history of malignant melanoma.

Comparison of the backbone dynamics of the apo- and holo-carboxy-terminal domain of the biotin carboxyl carrier subunit of Escherichia coli acetyl-CoA carboxylase.

The biotin carboxyl carrier protein (BCCP) is a subunit of acetyl-CoA carboxylase, a biotin-dependent enzyme that catalyzes the first committed step of fatty acid biosynthesis. In its functional cycle, this protein engages in heterologous protein-protein interactions with three distinct partners, depending on its state of post-translational modification. Apo-BCCP interacts specifically with the biotin holoenzyme synthetase, BirA, which results in the post-translational attachment of biotin to a single lysine residue on BCCP. Holo-BCCP then interacts with the biotin carboxylase subunit of acetyl-CoA carboxylase, which leads to the addition of the carboxylate group of bicarbonate to biotin. Finally, the carboxy-biotinylated form of BCCP interacts with transcarboxylase in the transfer of the carboxylate to acetyl-CoA to form malonyl-CoA. The determinants of protein-protein interaction specificity in this system are unknown. The NMR solution structure of the unbiotinylated form of an 87 residue C-terminal domain fragment (residue 70-156) of BCCP (holoBCCP87) and the crystal structure of the biotinylated form of a C-terminal fragment (residue 77-156) of BCCP from Escherichia coli acetyl-CoA carboxylase have previously been determined. Comparative analysis of these structures provided evidence for small, localized conformational changes in the biotin-binding region upon biotinylation of the protein. These structural changes may be important for regulating specific protein-protein interactions. Since the dynamic properties of proteins are correlated with local structural environments, we have determined the relaxation parameters of the backbone 15N nuclear spins of holoBCCP87, and compared these with the data obtained for the apo protein. The results indicate that upon biotinylation, the inherent mobility of the biotin-binding region and the protruding thumb, with which the biotin group interacts in the holo protein, are significantly reduced.

Structure of the carboxy-terminal fragment of the apo-biotin carboxyl carrier subunit of Escherichia coli acetyl-CoA carboxylase.

The biotin carboxyl carrier protein (BCCP) is a subunit of acetyl-CoA carboxylase, a biotin-dependent enzyme that catalyzes the first committed step of fatty acid biosynthesis. In its functional cycle the biotin carboxyl carrier protein engages in heterologous protein-protein interactions with three distinct partners, depending on its state of posttranslational modification. Apo-BCCP interacts specifically with the biotin holoenzyme synthetase, BirA, which results in the posttranslational attachment of biotin to an essential lysine residue on BCCP. Holo-BCCP then interacts with the biotin carboxylase subunit, which leads to the addition of the carboxylate group of bicarbonate to biotin. Finally, the carboxybiotinylated form of BCCP interacts with transcarboxylase in the conversion of acetyl-CoA to malonyl-CoA. The determinants of protein-protein interaction specificity in this system are unknown. One hypothesis is that posttranslational modification of BCCP may result in conformational changes that regulate specific protein-protein interactions. To test this hypothesis, we have determined the NMR solution structure of the unbiotinylated form of an 87 residue C-terminal domain fragment of BCCP (apoBCCP87) from Escherichia coli acetyl-CoA carboxylase and compared this structure with the high-resolution structure of the biotinylated form that was recently solved by X-ray crystallographic techniques. Although the overall folding of the two proteins is highly similar, small structural differences are apparent for residues of the biotin-binding loop that may be important for mediating specific protein-protein interactions.

Hyperkeratosis of the nipple and areola.

Usually hyperkeratosis of the nipple and areola is associated with ichthyosis and epidermal nevus. The patient's lesions will resemble acanthosis nigricans but histologically suggest a completely different entity. Presented is a case of hyperkeratosis of the nipples and areolae with no association with ichthyosis or epidermal nevus.