Evaluation of the gene encoding the tissue inhibitor of metalloproteinases-3 in various maculopathies.

PURPOSE: Mutations in the gene encoding the tissue inhibitor of metalloproteinases-3 (TIMP3) have been shown previously to cause Sorsby's fundus dystrophy, an autosomal-dominant disorder characterized by extracellular matrix irregularities in Bruch's membrane. To assess the involvement of TIMP3 in a variety of other macular dystrophies, the authors have screened this gene for disease-causing mutations in age-related macular degeneration (AMD), adult vitelliform macular dystrophy (AVMD), central areolar choroidal dystrophy (CACD), syndrome-associated macular dystrophies, cone-rod dystrophy, and a group with unspecified macular degeneration. METHODS: Single-stranded conformational analysis of the entire coding region was performed using the polymerase chain reaction and oligonucleotide primers flanking the five exons of the TIMP3 gene as well as the putative promotor region and a highly conserved fragment of the 3'-untranslated region. The authors analyzed a total of 217 patients, including 143 patients with AMD, 28 patients with AVMD, 21 patients with CACD, and 25 patients with other forms of macular dystrophy. RESULTS: In the 217 patients analyzed, the authors have identified one sequence alteration (a G-to-C base change) in the 5'-untranslated region in a patient with AMD. However, the functional consequences of this mutation are not clear. No other disease-causing mutations were found. The authors have characterized a frequent intragenic polymorphism in exon 3 of the TIMP3 gene (heterozygosity = 0.57) that will be useful for genetic linkage or allele sharing analyses or both. CONCLUSIONS: The authors' results suggest that TIMP3 is not a major factor in the cause of AMD, AVMD, and CACD. Thus far, Sorsby's fundus dystrophy appears to be the only phenotype known to be associated with mutations in TIMP3.

Who needs individual bioequivalence studies for narrow therapeutic index drugs? A case for warfarin.

Warfarin is, among drugs, considered to have a narrow therapeutic index for which individual bioequivalence has been suggested. To establish the propriety of "switching," an individual bioequivalence study involving a replicate-design study and three "switchings" in healthy subjects was undertaken using the U.S.-brand warfarin sodium tablet and a generic product. A randomized, single-center, open-label, single-dose, four-way crossover replicate bioequivalence study was performed in 24 healthy male volunteers in which each subject received the same 5 mg warfarin test and reference tablets twice on different occasions under fasting conditions. Concentrations of warfarin in plasma were measured by a validated specific HPLC method. The individual pharmacokinetic parameters obtained with test and reference products were compared using pooled data and Liu's method. Bioequivalence was shown with both average and individual bioequivalence methods. The individual bioequivalence assessment did not show a subject-by-formulation interaction, nor did it add value to the bioequivalence assessment of warfarin.

Nucleolar organizer regions in determining malignancy of pigmented conjunctival lesions.

We assessed the usefulness of silver staining of nucleolar organizer regions in the diagnosis of pigmented conjunctival tumors. Fifty-one biopsy specimens were silver stained to identify the nucleolar organizer regions. Nineteen nevi without atypia, three nevi with atypia, eight primary acquired melanosis lesions, and 14 melanomas were studied. In each specimen, silver staining of the nucleolar organizer regions was counted in 100 cells to yield an average of the silver staining of the nucleolar organizer region count. The mean silver staining of the nucleolar organizer region counts per cell was correlated with the degree of malignancy of pigmented conjunctival lesions as follows: nevi, 3.0; primary acquired melanosis, 3.2; nevi with atypia, 3.9; primary acquired melanosis with atypia, 5.0; and melanoma, 5.7 (Spearman correlation [rS] = .83, P = .0001; analysis of variance [ANOVA] F test = 20.9, P = .0001). A cutoff value of 4.0 (mean silver staining of nucleolar organizer regions per cell) will differentiate melanoma and primary acquired melanosis with atypia from other lesions (sensitivity, 100%; specificity, 96%). The silver staining of nucleolar organizer regions is a useful adjunct in determining the malignancy of pigmented conjunctival tumors.

Nucleolar organizer regions in optic gliomas.

The biological nature of optic gliomas is controversial, with some considering them benign hamartomatous lesions, and others believing them to be true neoplasms. We evaluated the use of colloid silver impregnation of nucleolar organizer region-associated proteins (AgNORs) in making this distinction. Thirty-one optic gliomas, 14 optic nerve meningiomas, and a single case of giant cell glioblastoma multiforme (monstrocellular glioma) of the optic chiasm were stained for AgNORs and counted in a masked fashion. The optic gliomas contained 2.01 +/- 0.09 AgNORs per nucleus, similar to that of optic nerve meningiomas (2.15 +/- 0.15) and our previously reported counts for diffuse fibrillary astrocytoma (2.22 +/- 0.10), and significantly more than that of reactive astrocytosis (1.18 +/- 0.02). Six of the seven optic gliomas examined had compound AgNORs, a feature associated with malignancy in other tumour types. AgNOR counts did not correlate with clinical features, including those seen during the post-operation course. These data suggest that optic gliomas may be true neoplasms, and not benign hamartomas.