Sequences of the folP1, rpoB, and gyrA genes were analyzed for 88 isolates of Mycobacterium leprae from leprosy patients in Japan, Haiti, Indonesia, Pakistan, and the Philippines. Thirteen isolates (14.8%) showed representative mutations in more than two genes, suggesting the emergence of multidrug-resistant M. leprae.

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Proteins involved in the formation of desmosomes and simpler adherens junctions were studied in three types of non-immune acantholytic diseases; specifically, four cases of Grover's disease (GD), one case of Hailey-Hailey's disease (HHD) and one case of Darier's disease (DD), and these were compared to two cases of immune-mediated acantholytic disease pemphigus vulgaris (PV). The proteins studied included: 1. The intracellular desmosomal proteins, desmoplakin I and II and plakoglobin; 2. The intercellular desmosomal proteins, desmoglein and CD44; and 3. vinculin, which is a major intracellular protein of the simpler aherens junctions. In GD, HHD and DD, immunostaining showed a loss of desmoplakin I and II and plakoglobin from the desmosomes, and a diffuse staining in the cytoplasm. In contrast, in pemphigus vulgaris, these proteins seemed intact and were localized to dot-like spots on the cell surface. Also, desmoglein, and CD44 were slightly affected in GD, and moderately affected in HHD and DD. Absence of desmosomal attachment plaques, the lack of labeling with desmoglein in the affected desmosomes and a diffusion of the labels into cytoplasm were demonstrated with electron microscopy using an immunogold technique. In PV, desmoglein III is one of the target antigens for the autoantibodies in this disease and was only partially preserved in a small number of lesional cells, while CD44 was mostly preserved. Vinculin was intact in GD, HHD and DD, but was lost in PV. This study, our previous work, and that of others, suggest that: 1. In GD, HHD and DD, the proteins of the desmosomal attachment plaque are primarily affected; 2. In PV, the intercellular glycoproteins are primarily involved; and 3. Simple adherens junctions are intact in GD, HHD and DD, but are damaged in PV.

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Multiple familial trichoepithelioma (MFT) is an autosomal dominant skin disease characterized by the presence of many small tumors predominantly on the face. To map the causative gene, we performed linkage analysis with microsatellite markers in three American families. We found a significant linkage of a gene for MFT to chromosome 9p2l. The maximum combined lod score was 3.31 at D9S171 at theta = 0. The disease locus was defined to a 4-cM region between IFNA and D9S126. Because several tumor suppressor genes including p16 and p15 have been mapped to this region, the gene for MFT may also be a tumor suppressor.

Host defense against Mycobacterium leprae infection is chiefly mediated by gamma interferon (IFN-␥؉ -and CD8 ؉ -T-cell subsets. M. leprae is a unique pathogen which remains resistant to DC-mediated T-cell immunity, at least in the early stages of infection.

Two cases of lichen amyloidosus and 8 cases of macular amyloidosis were examined by electron microscopy. Epidermal keratinocytes showed variable degrees of focal degeneration in the basal or lower Malpighian layer. The primary change was seen in cells which contain fibrillar (30 nm in thickness) cytoplasmic inclusion. The following developments seemed to lead to filamentous degeneration (colloid bodies): (1) aggregation of tonofilaments within the granular or fibrillar cytoplasm, (2) filamentous cells, which are composed of bundles of 7-nm thick filaments surrounded by cell membrane and desmosomes, and (3) filamentous masses composed of bundles or whorls of tightly packed 7-nm thick filaments in the intercellular spaces. At the dermo-epidermal junction, some of the filamentous masses were surrounded by the basal lamina of the epidermis and others were dropping into the dermis. Occasionally, loosened filaments (similar to amyloid filaments) were about to drop into the dermis. Early formation of amyloid islands consisted of electron-dense and electron-light parts. They were located directly beneath the epidermis. In the deeper postion of the papillary dermis and in the upper reticular dermis, the majority were electron-light masses. Electron dense parts were the densely packed 7-nm thick filaments, whereas electron-light parts were the typical straight amyloid filaments. Small tubular filaments were seen in common in the filamentous cells, filamentous masses, and amyloid islands. It is concluded that some of the amyloid substance in primary localized forms of cutaneous amyloidoses derive from the epidermal cells through filamentous degeneration.

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