Fiber-Optic Imaging Probe Developed for Space Used to Detect Diabetes Through the Eye

Approximately 16 million Americans have diabetes mellitus, which can severely impair eyesight by causing cataracts, diabetic retinopathy, and glaucoma. Cataracts are 1.6 times more common in people with diabetes than in those without diabetes, and cataract extraction is the only surgical treatment. In many cases, diabetes-related ocular pathologies go undiagnosed until visual function is compromised. This ongoing pilot project seeks to study the progression of diabetes in a unique animal model by monitoring changes in the lens with a safe, sensitive, dynamic light-scattering probe. Dynamic light scattering (DLS), has the potential to diagnose cataracts at the molecular level. Recently, a new DLS fiber-optic probe was developed at the NASA Glenn Research Center at Lewis Field for noncontact, accurate, and extremely sensitive particle-sizing measurements in fluid dispersions and suspensions (ref. 1). This compact, portable, and rugged probe is free of optical alignment, offers point-and-shoot operation for various online field applications and challenging environments, and yet is extremely flexible in regards to sample container sizes, materials, and shapes. No external vibration isolation and no index matching are required. It can measure particles as small as 1 nm and as large as few micrometers in a wide concentration range from very dilute (waterlike) dispersions to very turbid (milklike) suspensions. It is safe and fast to use, since it only requires very low laser power (10 nW to 3 mW) with very short data acquisition times (2 to 10 sec)

An Atypical Form of αB-crystallin Is Present in High Concentration in Some Human Cataractous Lenses IDENTIFICATION AND CHARACTERIZATION OF ABERRANT N- AND C-TERMINAL PROCESSING

Two unique polypeptides, 22.4 and 16.4 kDa, were prominent in some human cataracts. Both proteins were identified as modified forms of the small heat shock protein, αB-crystallin. The concentration of total αB-crystallin in most of these cataracts was significantly increased. The 22.4-kDa protein was subsequently designated as αBg. Mass spectrometric analyses of tryptic and Asp-N digests showed αBg is αB-crystallin minus the C-terminal lysine. αBg constituted 10–90% of the total αB-crystallin in these cataracts and was preferentially phosphorylated over the typical form of αB-crystallin. Human αBg and αB-crystallin were cloned and expressed inEscherichia coli. The differences in electrophoretic mobility and the large difference in native pI values suggest some structural differences exist. The chaperone-like activity of recombinant human αBg was comparable to that of recombinant human αB-crystallin in preventing the aggregation of lactalbumin induced by dithiothreitol. The mechanism involved in generating αBg is not known, but a premature termination of the αB-crystallin gene was ruled out by sequencing the polymerase chain reaction products of the last exon for the αB-crystallin gene from lenses containing αBg. The 16.4-kDa protein was an N-terminally truncated fragment of αBg. The high concentration of αB-crystallin in these cataracts is the first observation of this kind in human lenses

Complicated spastic paraplegia in patients with AP5Z1 mutations (SPG48)

Objective: Biallelic mutations in the AP5Z1 gene encoding the AP-5 ζ subunit have been described in a small number of patients with hereditary spastic paraplegia (HSP) (SPG48); we sought to define genotype–phenotype correlations in patients with homozygous or compound heterozygous sequence variants predicted to be deleterious. Methods: We performed clinical, radiologic, and pathologic studies in 6 patients with biallelic mutations in AP5Z1. Results: In 4 of the 6 patients, there was complete loss of AP-5 ζ protein. Clinical features encompassed not only prominent spastic paraparesis but also sensory and motor neuropathy, ataxia, dystonia, myoclonus, and parkinsonism. Skin fibroblasts from affected patients tested positive for periodic acid Schiff and autofluorescent storage material, while electron microscopic analysis demonstrated lamellar storage material consistent with abnormal storage of lysosomal material. Conclusions: Our findings expand the spectrum of AP5Z1-associated neurodegenerative disorders and point to clinical and pathophysiologic overlap between autosomal recessive forms of HSP and lysosomal storage disorders

Complicated spastic paraplegia in patients with AP5Z1 mutations (SPG48).

OBJECTIVE: Biallelic mutations in the AP5Z1 gene encoding the AP-5 ζ subunit have been described in a small number of patients with hereditary spastic paraplegia (HSP) (SPG48); we sought to define genotype-phenotype correlations in patients with homozygous or compound heterozygous sequence variants predicted to be deleterious. METHODS: We performed clinical, radiologic, and pathologic studies in 6 patients with biallelic mutations in AP5Z1. RESULTS: In 4 of the 6 patients, there was complete loss of AP-5 ζ protein. Clinical features encompassed not only prominent spastic paraparesis but also sensory and motor neuropathy, ataxia, dystonia, myoclonus, and parkinsonism. Skin fibroblasts from affected patients tested positive for periodic acid Schiff and autofluorescent storage material, while electron microscopic analysis demonstrated lamellar storage material consistent with abnormal storage of lysosomal material. CONCLUSIONS: Our findings expand the spectrum of AP5Z1-associated neurodegenerative disorders and point to clinical and pathophysiologic overlap between autosomal recessive forms of HSP and lysosomal storage disorders

Non-Invasive Evaluation of Corneal Abnormalities Using Static and Dynamic Light Scattering

A preliminary study of corneal abnormalities in intact bovine eyes is presented. Twenty-one eyes were treated with chemicals, cotton swabs, and radial and photo-refractive surgeries. Dynamic and static light scattering was performed as a function of the penetration depth into the corneal tissue. Topographical maps of corneal refractive power from untreated and treated corneas were also obtained using videokeratoscopy and results compared. The ultimate aim is to develop the technique of dynamic light scattering (DLS) for clinical applications in early evaluation of corneal complications after laser-assisted in situ keratomileusis (LASIK) surgeries and other corneal abnormalities