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Biomedical subjects

B W Streeten

Publications and source records attributed to B W Streeten.

At least 19 recordsLinked to original sources
PubMed1992

Characterization of an associated microfibril protein through recombinant DNA techniques.

The complete primary structure of a new extracellular protein associated with elastic fiber microfibrils was determined by recombinant DNA techniques. Antiserum to insoluble bovine ocular zonule protein was used to screen a lambda gt11 cDNA expression library constructed from whole chick embryo poly(A)+ RNA. The cDNAs encoding immunoreactive fusion polypeptides were then used to rescreen the library by plaque hybridization. Nucleotide sequencing of overlapping cDNA clones revealed an open translation reading frame of 1326 bases beginning at an initiation start sequence and ending at a stop codon. The contiguous cDNA sequence contains a 3'-untranslated region of 563 bases with a possible polyadenylation site 16 bases upstream from the poly(A) tail. Primer extension of chick aortic mRNA taken together with the sequence data, reveals a 5'-untranslated region of 95 bases extending upstream from the translation start site. Northern blot analyses indicated that the isolated cDNA hybridized with a 2.1-kilobase mRNA in preparations of whole chick embryo and chick embryonic aortic, heart, and muscle RNAs. The initial translation protein encoded by the cDNA is 53,932 kDa and possesses a hydrophilic amino acid composition with glutamic acid comprising 22% of the total amino acid residues. Antiserum was elicited to a synthetic peptide sequence (14 amino acids) encoded within the deduced protein primary structure. Western blots of extracted proteins from chick embryonic aortae cultured in the presence of beta-aminopropionitrile showed that the medium and a mild salt extract contained an immunoreactive protein possessing an apparent molecular mass of 58,000 whereas harsh denaturants extracted a 32,000-kDa protein. Pulse-chase experiments using radiolabeled lysine showed that the newly synthesized 58,000-kDa protein was chased into a 32,000-kDa protein within a 2-24-h period. Immunoelectron microscopy of tissue sections from chick aortae, bovine nuchal ligament, and human ocular zonules showed that the peptide-elicited antibody localized specifically to ultrastructurally definable microfibril structures.

Amino Acid Sequence↗
PubMed1992

Pseudoexfoliative fibrillopathy in visceral organs of a patient with pseudoexfoliation syndrome.

Evidence is increasing that pseudoexfoliative material develops in widespread areas of skin and parabulbar tissues as well as intraocularly. To determine whether this process is even more diffusely distributed, ultrastructural examination was performed on visceral and ocular tissues of a patient with long-standing glaucoma found to have bilateral ocular pseudoexfoliation at autopsy. Aggregates consistent with pseudoexfoliative material were present in the lung, heart, liver, and gallbladder, in addition to the classic intraocular sites. The aggregates were in the fibrovascular septa and stroma of these organs, most frequently adjacent to elastic and oxytalan fibers. They stained positively for elastin and human amyloid P protein, like the ocular sites, in preliminary immunologic testing. Rare atypical aggregates were seen in one of the four control patients. These findings suggest that pseudoexfoliation is a systemic process involving abnormal matrix synthesis, particularly as related to elastic tissue components.

Aged↗
PubMed1992

Molluscum contagiosum of the eyelids in patients with acquired immune deficiency syndrome.

BACKGROUND: Infection with molluscum contagiosum has been reported in patients with acquired immune deficiency syndrome (AIDS). Involvement of the eyelids by molluscum in patients with AIDS has rarely been mentioned. METHODS: Two patients with AIDS presented with eyelid molluscum contagiosum. Detailed examination and follow-up was performed. RESULTS: One patient had noted ocular irritation with epiphora for several weeks and showed a typical viral keratoconjunctivitis in both eyes. The other patient progressed to confluent masses involving the entire lower eyelid on one side. Removal of the lesions by surgery and cryotherapy was followed by recurrences in both patients within 6 to 7 weeks, the incubation period for this viral infection. CONCLUSION: Molluscum contagiosum can form confluent lesions on the eyelids in patients with AIDS, which may cause a keratoconjunctivitis. Local removal of molluscum eyelid nodules appears to be of limited long-term value in patients with T-cell immunodeficiency.

AIDS-Related Opportunistic Infections↗
PubMed1991

Abnormal scleral collagen in nanophthalmos. An ultrastructural study.

Ten patients with bilateral nanophthalmos underwent sclerectomies for uveal effusion. Ultrastructural examination of the sclera revealed abnormal collagen in seven patients. Four showed dramatic fraying of the collagen fibrils into fine filaments 2 to 3 nm in diameter. In three of these cases and three other cases without fraying, there were foci of 10- to 35-nm small collagen fibrils, some appearing to arise by splitting of otherwise normal collagen fibrils. In areas of fraying, elastic fibers were absent. All patients had a wider range of collagen diameters than did control subjects. The youngest patient with fraying also had Hallermann-Streiff syndrome. In three patients, no collagen abnormality was found. The clinical feature correlating best with the presence of abnormal collagen was an extremely small eye, since the three patients without collagen abnormality had the largest eyes (range of anteroposterior diameters, 19.2 to 20.3 mm). Nanophthalmos appears to result from several distinct defects.

Adult↗
PubMed1991

Rotary shadowing of elastic system microfibrils in the ocular zonule, vitreous, and ligamentum nuchae.

Rotary shadowing of zonular fibrils in human and bovine eyes revealed a "string of beads" configuration with multiple interconnecting filaments, identical to that recently reported in fibrils of unknown type within the vitreous. These 29 nm beaded fibrils were the only macrostructures present in zonular samples, showing ultrastructural features correlating with both the macro and microperiodicity of zonular fibrils in tissues. Interbead periodicity varied from 30-57 nm and interbead filaments appeared capable of stretching even further, possibly explaining the inherent elasticity of zonular fibrils. The junctions between outer filaments and beads were fibrillin-positive. Similar beaded fibrils were found in the human and bovine anterior vitreous along with type II and IX collagen fibrils, proteoglycan filaments and other unidentified fibrils. After collagenase and elastase digestion, bovine ligamentum nuchae showed type VI collagen fibrils and clumps of beaded fibrils like those in zonule and vitreous. This distribution indicates that the beaded fibril is the microfibril which constitutes the basic unit of the elastic system.

Animals↗
PubMed1991

Elastic fiber components and protease inhibitors in pinguecula.

The nature of the abnormal elastotic materials seen in pingueculae and their insensitivity to elastase are poorly understood. The authors investigated their composition by immunoelectron microscopy using antibodies to elastic fiber components, serum and tissue components known to be associated with elastosis in other sites. The abnormal elastic fibers showed labeling for elastin, microfibrillar protein, and amyloid P where these components never co-localize normally, indicating the fibers are not simply immature but aberrant in organization. There was mild positivity for the serum protease inhibitor alpha-1 antitrypsin at the edges of the abnormal elastic tissue and marked positivity for lysozyme. The more superficial region of pingueculae had similar elastic constituents but no fiber formation and a paucity of elastic microfibrils. The subepithelial dense concretions showed strong staining for lysozyme, the first component to be identified in these aggregates. Amyloid P and lysozyme are characteristic components of dermal elastosis, postulated to have an inhibitory effect on elastolytic processes, indirectly affecting the control of elastogenesis. The greater prominence of nonfiber-forming aggregates in pingueculae may be related to their marked deficiency of elastic microfibrils compared with dermal elastoses. This difference speaks for more severe actinic cellular damage in the poorly protected conjunctival tissue.

Aged↗
PubMed1990

Pseudoexfoliative fibrillopathy in the skin of patients with ocular pseudoexfoliation.

In addition to its occurrence within the eye, pseudoexfoliative fibrillopathy has been reported in the conjunctiva and around a posterior ciliary artery. To determine whether it has a more diffuse extraocular distribution, we studied skin biopsy specimens ultrastructurally from one to three areas in 13 patients with classic pseudoexfoliation. A fibrillopathy closely resembling that in the eye was found in 11 of the 13 patients. Only one of the 13 control subjects, a 78-year-old man with advanced low-tension glaucoma, had a similar fibrillopathy. In the patients with pseudoexfoliation who were more than 70 years of age, the accompanying dermal elastosis made evaluation difficult, because the pseudoexfoliative nodules in the skin occur primarily along elastic fibers, and their morphologic characteristics appeared to be influenced by the elastotic process. These results suggest that pseudoexfoliation is a systemic process related closely to elastosis, and that further search for pseudoexfoliative fibers should be made in the elastic system of the deep tissues and internal organs.

Aged↗
PubMed1990

Necrobiotic xanthogranuloma with IgA multiple myeloma: a case report and literature review.

The association between necrobiotic xanthogranuloma of the dermis and paraproteinemia and/or B-cell malignancy is best described in the ophthalmologic literature. We report a case which occurred in the eyelid and orbit of a 64 year old man that led to the diagnosis of an IgA multiple myeloma. To our knowledge, this is the first report of an IgA type paraproteinemia and IgA type multiple myeloma associated with necrobiotic xanthogranuloma.

Granuloma↗
PubMed1990

Precapsular film on the aging human lens: precursor of pseudoexfoliation?

In many older patients we observed a layer of subtle opacification on the anterior lens capsule, appearing as a ground glass film biomicroscopically. This precapsular film (PCF) could be uniform but often had radial grey lines in the mid zone, holes in the paracentral region, and was occasionally rolled up in strings. Lens capsular material obtained at cataract extraction was studied in patients with and without the film. By scanning electron microscopy the PCF appeared as a friable, incomplete fibrillar layer, with rolling of the edges suggesting loose attachment. Ultrastructurally its component fibrils were from 3-6 nm in diameter, similar to the finer fibrils in pseudoexfoliation (PSX) material. Life PSX material the layer stained positively for the elastic microfibril-associated protein, fibrillin, in a lens with radial striations. These similarities suggested that the two conditions have some relationship and that the PCF may be a precursor of PSX. Finding patches of the fibrillar network in some control patients implies that the PCF is common in patients of cataract age, though seldom detected clinically.

Aged↗
PubMed1989

Amyloid P protein in pseudoexfoliative fibrillopathy.

Amyloid P protein was demonstrated by immunostaining in all 14 samples of ocular and conjunctival pseudoexfoliative (PSX) material studied, although amyloid was not found by Congo red staining or ultrastructurally. Immunostaining of PSX aggregates for other common amyloid proteins, including amyloid A, prealbumin, and immunoglobulin light chains, was negative in most cases. In three eyes with advanced neovascular glaucoma there was irregular immunostaining of the PSX aggregates for 2-4 of these other amyloid proteins, besides diffuse staining of the iris and vitreous. Control cases of neovascular glaucoma without PSX disease showed minimal amyloid P, but similar tissue staining for prealbumin and immunoglobulin light chains, consistent with an origin from vascular leakage. The presence of amyloid P protein, a minor serum component, in PSX aggregates in all cases with or without evidence of vascular leakage, indicated a more specific association. Ultrastructural localization of the protein on the periphery of PSX fibers suggest it is not an intrinsic fiber component. Since PSX material has an immunological relation to elastic tissue, we propose that PSX fibers have peripheral binding sites for amyloid P protein, similar to those present on normal elastic fibers.

Aged↗
PubMed1988

Identification of extractable proteins from the bovine ocular zonule: major zonular antigens of 32kD and 250kD.

Using Western immunoblotting, the extractable proteins of the bovine zonular fibers were examined for reactivity with two zonular antisera known to have strong affinity for zonular fibers in tissues, in order to identify the antigenic components. The extracts were also tested with antisera to several matrix proteins that have been reported to be associated with zonular fibers. Proteins reactive with antisera to bovine serum albumin, serum immunoglobulins and fibronectin were present. No bands reactive with antisera to a-elastin, prealbumin, amyloid P component, collagen VI, lysyl oxidase or monoclonal antibody to fibrillin were demonstrated. The major nonserum protein band identified by both antisera was a 32kD polypeptide. An equally strong 250kD polypeptide was shown by the antiserum to guanidine-dithiothreitol extracted zonular fibers. Both of these proteins were PAS-positive and were demonstrated also by the antisera in extracts of bovine elastic neck ligament. Whether the two glycoproteins are related to each other, with the higher molecular weight protein either a precursor or aggregate form, is not yet clear. They appear to bear a close relationship to the elusive core microfibrillar protein.

Animals↗
PubMed1988

Association of elastin with pseudoexfoliative material: an immunoelectron microscopic study.

Using immunoelectron microscopy, the presence of elastin and tropoelastin was demonstrated in pseudoexfoliative (PSX) material in all its classical sites on the lens capsule, ciliary non-pigment epithelium, iris epithelium and stroma, and conjunctiva. Some variability in binding affinity was seen in different sites, and labelling was more often on the periphery than the center of the PSX fibers. The elastin epitope on PSX material was more sensitive to processing than the remarkably stable epitope on mature elastic fibers. Since neither elastin nor a related component of PSX fibers, elastic microfibrillar protein, is a circulating protein, both are likely to be secreted by local ocular cells. Most of these local cells are not involved in elastogenesis normally, suggesting that an abnormal stimulus or defective regulation of matrix synthesis exists in this disease.

Actin Cytoskeleton↗
PubMed1987

Preclinical diagnosis of pseudoexfoliation syndrome.

Although the diagnosis of pseudoexfoliation syndrome (PXS) is made by observation of pseudoexfoliation material (PXM) deposited on the anterior lens capsule, there are several additional signs related to pigment dispersion that are often present both in eyes with PXS and fellow eyes in unilateral cases. On the basis of the presence of these signs, we have categorized a group of patients as "pseudoexfoliation suspects" who demonstrated no evidence of PXM on the lens capsule in either eye. As PXM has previously been identified in the conjunctiva of affected eyes as well as fellow eyes in unilateral cases, we hypothesized that it could also be present in PXS suspect eyes. Inferior bulbar conjunctival biopsies were performed on four eyes with PXS, five fellow eyes, and 23 PXS suspect eyes, and specimens were examined by transmission electron microscopy. In eight PXS suspect eyes biopsy specimens demonstrated PXM, suggesting that PXS is more prevalent and possibly responsible for a greater proportion of glaucoma than previously suspected.

Aged↗
PubMed1987

Lens capsule abnormalities in Alport's syndrome.

The ultrastructure of the glomerular basement membrane in Alport's syndrome is well known and characteristic of this disease, but the anterior lenticonus that frequently occurs in this syndrome has not been similarly studied. An anterior lens capsule from a 30-year-old patient with lenticonus who had Alport's syndrome was obtained at capsulectomy and found to be one third the normal thickness centrally and to be more fibrillar than usual. There were large numbers of partial capsular dehiscences containing fibrillar material and vacuoles. Cellular debris and more recent ruptures of lens epithelial cell membranes underlaid the breaks. The anterior capsule is clearly fragile in this disease, forming the basis for the progressive lenticonus and anterior polar cataract. These abnormalities correlate well with a defect in the type IV collagen molecule, as has been recently reported in Alport's syndrome.

Adult↗
PubMed1987

Pseudoexfoliative fibrillopathy in the conjunctiva. A relation to elastic fibers and elastosis.

Pseudoexfoliative (PSX) material in the conjunctiva was found to have a close association with elements of the elastic system in 13 eyes of patients with PSX disease studied ultrastructurally. Pseudoexfoliation aggregates were rare within vascular walls but frequent in proximity to the plasmalemma of stromal fibroblasts. No amyloid was found. A striking feature was the association of PSX fibers with the elastosis seen in many of the specimens. Typical PSX fibers were present in clumps of oxytalan and around small elastic fibers. In five cases with more advanced elastosis, the aggregates of PSX fibers were larger and their usual loose fibrogranular matrix was extensively replaced by a dense elastotic one. Morphology of PSX here varied from typical to thicker, fragmented, and sometimes nondiagnostic fibers. This intermingling of PSX and elastotic materials suggested that PSX fibrillopathy is itself a type of elastosis, possibly resulting from abnormal aggregation of components related to elastic microfibrils.

Actin Cytoskeleton↗
PubMed1987

Localized conjunctival amyloidosis associated with extranodal lymphoma.

A 62-year-old man was found to have a large asymptomatic amyloid nodule of the conjunctiva. Within the next year, a diffuse mixed small and large cell lymphoma of his scapula developed with amyloid in its stroma. No abnormal serum or urine protein was found. Subsequently, rib and paraspinal masses appeared. After irradiation and chemotherapy, the patient died of bronchopneumonia, 3 years after onset. By immunostaining, the amyloid of both conjunctiva and scapular tumor was of polyclonal immunoglobulin (AL) type, most prominently IgG and lambda chains, with lesser staining for IgA and kappa chains. The tumor cells showed a similar pattern. To our knowledge, this is the first report of systemic lymphoma and localized conjunctival amyloidosis without a serum paraprotein, and the first such association with a lymphoma of this cell type. Immunotyping of conjunctival amyloidosis should be performed to guide the workup for possible systemic disease.

Amyloidosis↗
PubMed1987

Histopathology of herpes simplex virus keratouveitis.

Twenty-four eyes removed for complications of HSV keratitis were studied histopathologically. There were 20 men and 4 women with an average age of 61 years. Severe keratitis was seen in 14, moderate in 7, and mild in 3 eyes. Common features associated with severe keratitis were: acute perforation, granulomatous keratitis with giant cells in the stroma and Descemet's region, stromal inflammatory cells, angle-closure, severe iridocyclitis with diffuse or focal infiltration of lymphocytes and plasma cells, low-grade vitritis, choroiditis, and/or retinal periphlebitis. Specimens with moderate to mild keratitis had a similar distribution of inflammation but a lower incidence of granulomatous keratitis.

Adult↗