PubMed · 13324941
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G C PRATHER, D SKINNER. Prostatic corpora amylacea.. https://pubmed.ncbi.nlm.nih.gov/13324941/
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AIMS: Gelatinous drop-like corneal dystrophy (GDLD) is an early-onset, autosomal recessive condition characterised by amyloid deposits within the cornea. We report the histopathological and molecular genetic findings in a Caucasian child with GDLD who also exhibited global developmental delay. METHODS: Bilateral lamellar keratoplasty was carried out at age 6 and 7 years. Tissue was fixed for light and electron microscopy, including immunoelectronmicroscopy. The coding region of the M1S1 gene was screened for mutations in the affected proband and available relatives, using DNA extracted from mouthwashes. RESULTS: Nodular deposits, which were present subepithelially and in the central superficial stroma, stained typically for amyloid with PAS and Congo red. A nodular deposit of amyloid, together with large amounts of lactoferrin and sparse amounts of keratoepithelin (betaig-h3), was present in the central superficial stroma, causing destruction of Bowman's layer and elevation of the thinned, degenerate epithelium. Around the deposit zone, the stroma exhibited large numbers of thick filamentous proteoglycan deposits. While the affected child was homozygous for a novel A1133 C single-nucleotide polymorphism (SNP) that resulted in an aspartic acid to alanine substitution at position 173 of the M1S1 coding sequence, this polymorphism was also found at relatively high frequency in a sample of normal controls, enabling exclusion of the M1S1 gene as the disease locus. CONCLUSION: Increased epithelial permeability in GDLD may be explained in part by an altered membrane permeability of the superficial epithelial cells. An association with developmental delay has not been reported previously.
Atomic force microscopy was employed to study ex vivo amyloid material isolated from the transplanted hearts of two patients affected by systemic amyloidosis caused by the Leu174Ser apolipoprotein A-I variant. The purified material consists of fibrils and globular aggregates. For both patients the same morphological patterns are observed; in addition, fibril diameters obtained for the two patients turn out to be compatible, both in air (2.00+/-0.02 and 2.04+/-0.04 nm) and under liquid (10.7+/-0.4 and 11.3+/-0.5 nm). Fibrils display heterogeneous morphologies, occasionally showing a left-handed twist. Inspection of fibril ends, the study of fibril contour shape and the analysis of partially unfolded fibrils yield independent evidences suggesting that most twisted fibrils are composed of three protofilaments. The size of globular aggregates is the same for both patients (4.4+/-0.4 and 5.1+/-0.5 nm, measured under liquid) and is compatible with the protofilament expected diameter, suggesting that globules may represent protofilament precursors.
Here we investigated the effects of 2,2,2-trifluoroethanol (TFE) on the structure of alpha-chymotrypsin. The protein aggregates maximally in 35% (v/v) TFE. Congo red and thioflavin-T binding experiments suggest that the aggregates induced by TFE have amyloid-like properties, and transmission electron microscopy data show that these aggregates have a fibrilar morphology. Fluorescence, circular dichroism, anilino-8-napthalene sulfonate binding, and Fourier-transformed infrared spectroscopy data suggest that formation of a partially structured intermediate state precedes the onset of the aggregation process. The native beta-barrel structure of alpha-chymotrypsin appears to be disrupted in the partially structured intermediate state in favour of a non-native extended beta-sheet conformation with exposed hydrophobic surfaces. The protein becomes "sticky" under these conditions and aggregates into amyloid-like structures. The data support the hypothesis that amyloid formation involves the ordered self-assembly of partially folded species that are critical soluble precursors of fibrilar aggregates.