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Biomedical subjects

R W Nowakowski

Publications and source records attributed to R W Nowakowski.

9 recordsLinked to original sources
PubMed1998

OA1 mutations and deletions in X-linked ocular albinism.

X-linked ocular albinism (OA1), Nettleship-Falls type, is characterized by decreased ocular pigmentation, foveal hypoplasia, nystagmus, photodysphoria, and reduced visual acuity. Affected males usually demonstrate melanin macroglobules on skin biopsy. We now report results of deletion and mutation screening of the full-length OA1 gene in 29 unrelated North American and Australian X-linked ocular albinism (OA) probands, including five with additional, nonocular phenotypic abnormalities (Schnur et al. 1994). We detected 13 intragenic gene deletions, including 3 of exon 1, 2 of exon 2, 2 of exon 4, and 6 others, which span exons 2-8. Eight new missense mutations were identified, which cluster within exons 1, 2, 3, and 6 in conserved and/or putative transmembrane domains of the protein. There was also a splice acceptor-site mutation, a nonsense mutation, a single base deletion, and a previously reported 17-bp exon 1 deletion. All patients with nonocular phenotypic abnormalities had detectable mutations. In summary, 26 (approximately 90%) of 29 probands had detectable alterations of OA1, thus confirming that OA1 is the major locus for X-linked OA.

Albinism, Ocular↗
PubMed1997

Retinopathy secondary to anemia from myeloid metaplasia in polycythemia vera.

BACKGROUND: Polycythemia vera is a chronic clonal disorder associated with excessive proliferation of erythrocytes, leukocytes, and thrombocytes, as well as an accompanying splenomegaly. Ocular manifestations of polycythemia vera include occipital cortex transient ischemic attacks, transient monocular blindness, vaso-occlusive disease, and retinal hemorrhages. CASE REPORT: A 56-year old man with longstanding polycythemia vera sought treatment for a chief symptom of blurred vision in the left eye and a red tinge to things first noticed on awakening that morning. He had preretinal and intraretinal hemorrhages and was subsequently found to be severely anemic as a result of postpolycythemic myeloid metaplasia after years of phlebotomy. Splenectomy controlled his anemia and thrombocytopenia, allowing transient improvement of the retinal hemorrhages. Acute leukemia subsequently developed and the patient died 7 weeks after initial examination. CONCLUSION: In this case, preretinal and intraretinal hemorrhages were found in a patient with longstanding polycythemia vera. The exact origin of these hemorrhages is uncertain. They are probably secondary to anemia, but the possibility that they are sites of extramedullary hematopoiesis must be considered. The appearance of retinal hemorrhages warrants careful investigation to rule out diabetes, hypertension, and anemia, as well as the various other blood dyscrasias.

Anemia↗
PubMed1990

A screening method for mucopolysaccharidoses with increased urinary excretion of sulfated N-acetylhexosamines.

Patients with mucopolysaccharidosis have been reported to excrete elevated amounts of sulfated N-acetylhexosamines in their urine. Based on this finding, a new and simple colorimetric screening test for these disorders is presented. Chromatography of whole urine on Dowex AG 1-X8, from each of 23 normal controls, 5 patients with mucopolysaccharidosis and one patient with multiple sulfatase deficiency, was used to separate the sulfated hexosamines. The fractions eluted with 2M NaCl were analyzed according to the method of Reissig. Patients with Sanfilippo syndrome, type A, Sanfilippo syndrome, type D, Maroteaux-Lamy syndrome, Morquio syndrome, type A, and multiple sulfatase deficiency were clearly distinguished from normal controls. The procedure appeared most sensitive for Sanfilippo syndrome, type D, and multiple sulfatase deficiency, each of which involves deficient activity of N-acetylglucosamine 6-sulfate sulfatase.

Chromatography, Ion Exchange↗
PubMed1989

Sanfilippo syndrome, type D: a spectrophotometric assay with prenatal diagnostic potential.

Sanfilippo syndrome, type D (MPS IIID), is characterized by moderate physical abnormalities, progressive mental deterioration, and deficient activity of N-acetylglucosamine 6-sulfate sulfatase, a lysosomal hydrolase involved in the degradation of heparin, keratan sulfate, and heparan sulfate. To date, demonstration of the enzyme deficiency typically relies on a radiolabeled trisaccharide substrate derived from heparan sulfate. In our study, we have developed a spectrophotometric assay for the determination of N-acetylglucosamine 6-sulfate sulfatase activity using the monosaccharide, N-acetylglucosamine 6-sulfate, as substrate. The reaction mixture was incubated for 6 h at 37 degrees C and, after Dowex chromatography, released N-acetylglucosamine was measured by a modification of the method of Reissig. Assay conditions were optimized for cultured skin fibroblasts and primary cultures of amniotic fluid cells. The pH optimum for each was 5.5. The assay was linear for 24 h and up to 0.1 absorbance units. Activities of the three known MPS IIID skin fibroblast cell lines were more than 4 SD below the skin fibroblast control mean and more than 5 SD below the control mean for amniotic fluid cells. An enzyme deficiency in cultured amniotic fluid cells of the same magnitude as the skin fibroblasts of the known patients would be detectable and, therefore, prenatal diagnosis by this method is feasible.

Amniotic Fluid↗
PubMed1988

Leber optic atrophy low vision case report.

Leber optic atrophy (LOA) is a familial disorder primarily affecting males. We report the case of a 44-year-old male for whom the prescription of low vision aids was an important rehabilitative factor.

Adult↗
PubMed1988

Diagnosis of feline GM1 gangliosidosis by enzyme assay of cultured conjunctival cells.

GM1 gangliosidosis is characterized by a deficiency in the lysosomal hydrolase beta-galactosidase, progressive nervous system disease and ocular lesions. Diagnosis of GM1 gangliosidosis in humans and cats with the analogous disease has been made by measurement of the enzyme activity in various tissues including brain, liver and cultured skin fibroblasts. The authors report the use of cultured conjunctival cells for this purpose derived from cats with feline GM1 gangliosidosis, a model of the human disease (juvenile GM1 gangliosidosis, Derry's disease). Full thickness conjunctival biopsies from three cats with GM1 gangliosidosis and two normal controls were used to initiate cell cultures. Optimal conditions for beta-galactosidase activity were established with an uncultured conjunctival biopsy from a normal cat. The fluorgen, 4-methylumbelliferyl-beta-D-galactopyranoside was used as substrate. After 2 months in culture, and 2 weeks after subculture, cells from cats affected with GM1 gangliosidosis exhibited specific activities for beta-galactosidase of 10, 9 and 12 nmoles 4MU/hr/mg protein, whereas specific activities for normals were 630 and 469 nmoles 4MU/hr/mg. Enzymatic analysis of cultured conjunctival cells may offer an effective alternative for the diagnosis of GM1 gangliosidosis.

Animals↗
PubMed1984

Bayes' theorem and X-linked ophthalmic disorders.

Many X-linked disorders are confined to the eye or have ocular manifestations. The provision of genetic counseling for potential carriers requires accurate risk assessment. An application of Bayes' theorem to risk assessment for the daughter of an obligate carrier, and her daughter, is given.

Adult↗