PubMed Health⌕ Search

Biomedical subjects

T J Stokkermans

Publications and source records attributed to T J Stokkermans.

6 recordsLinked to original sources
PubMed1999

Diffuse unilateral subacute neuroretinitis.

BACKGROUND: Diffuse unilateral subacute neuroretinitis (DUSN) is an inflammatory disorder of the retina thought to be caused by a motile worm. It initially presents with unilateral recurring crops of gray-white retinal lesions and mild to severe inflammation. Over a period of months, diffuse retinal pigment epithelium (RPE) changes, arteriolar attenuation, and optic atrophy will develop. In approximately 25% of cases, a worm is visualized during the eye examination. Laser treatment to kill the worm is the only reliable way to halt progression of this disease. METHODS: The following case report presents a 9-year-old girl with unilateral vision loss. RESULTS: Clinical observation and several blood tests to rule out systemic diseases resulted in a diagnosis of DUSN. Although a worm was not visualized, laser treatment of its suspected location resulted in recovery of some vision. CONCLUSIONS: DUSN is often diagnosed by clinical presentation alone, because a worm may not be visualized. An appropriate initial work-up and timely initiation of laser treatment are essential to preservation of vision.

Acute Disease↗
PubMed1998

Solar retinopathy in a hospital-based primary care clinic.

BACKGROUND: Most reports of solar retinopathy describe epidemics of patients who go to the eye doctor after viewing a solar eclipse. Rarely is it encountered by the primary eye care provider during a routine eye examination. METHODS: For 26 months, patients who went to the primary care eye clinic and found to have macular lesions consistent with solar retinopathy were identified from the total clinic population. These patients were documented in a coded log and fundus photographs were obtained (when possible). RESULTS: Twenty-six eyes of twenty patients (0.14% incidence) were determined to have macular lesions consistent with solar retinopathy. Visual acuity was 20/25 or better in 100% of the patients and 85% were 20/20. Patients were predominantly men (75%) of middle age (average age, 43 years; SD, 11 years) with a history relevant for solar retinopathy (80%)--consisting of sungazing, 60%; looking at welding light without eye protection, 15%; substance abuse, 15%; and psychiatric condition, 5%. Forty percent had solar lesions in both eyes. Amsler grid testing revealed a defect in only 20%, and macular threshold visual-field testing was normal in all the eyes tested. CONCLUSIONS: This is the first report to characterize solar retinopathy in a primary eye care population. Management includes correct differentiation from other macular disorders, acquisition of a careful detailed history, and provision of patient education regarding the dangers of sungazing.

Adolescent↗
PubMed1996

Inhibition of Toxoplasma gondii replication by dinitroaniline herbicides.

Submicromolar concentrations of several dinitroaniline herbicides have been found to specifically inhibit intracellular replication of the protozoan parasite Toxoplasma gondii. IC50 concentrations for T. gondii survival were approximately 100 nM for ethalfluralin and oryzalin and approximately 300 nM for trifluralin. Primary human fibroblasts employed as host cells for parasite culture were unaffected at > 100-fold higher concentrations. Extracellular parasites were unaffected by these drugs, but within 8 hr after treatment of infected cell cultures, intracellular tachyzoites formed large amorphous bodies containing distorted nuclei. Parasite cytokinesis was completely blocked by drug treatment; nucleic acid synthesis, however, continued at near-normal levels for several days in the continuous presence of drug. All dinitroanilines appear to block nuclear division by inhibition of intranuclear spindle formation, but other cytoskeletal components were differentially affected by the various drugs tested. Subpellicular microtubules were absent in oryzalin-treated parasites, and large fragments of the inner membrane complex were observed throughout the parasite cytoplasm. In contrast, subpellicular microtubules and the inner membrane complex remained intact in ethalfluralin-treated parasites, but the endoplasmic reticulum and nuclear envelope were highly distended. Cytoskeletal elements associated with the conoid were not affected by any of the dinitroanilines tested, and treatment with the Ca2+ ionophore A23187 failed to trigger release of drug-treated parasites from infected cells. Mutant parasites resistant to oryzalin, ethalfluralin, or trifluralin were selected by chemical mutagenesis and examined for cross-resistance. An ethalfluralin-resistant mutant displayed cross-resistance to both oryzalin and trifluralin, while a trifluralin-resistant mutant was sensitive to oryzalin and only partially resistant ethalfluralin; an oryzalin-resistant mutant exhibited higher resistance to ethalfluralin and trifluralin than to oryzalin itself. Similarities between Apicomplexan and plant tubulin are discussed.

Animals↗
PubMed1995

Structural requirements of synthetic and natural product lipo-chitin oligosaccharides for induction of nodule primordia on Glycine soja.

Rhizobia synthesize a class of lipo-chitin oligosaccharides that induce root hair deformation and induce the initiation of nodule structures on legume roots. These lipo-chitin oligosaccharides are tetra- and penta-lipo-oligosaccharides of N-acetylglucosamine with an acyl substitution on the nonreducing end and are commonly known as Nod factors. In this study, we demonstrate that synthetic analogs of natural product Nod factors have the same biological activities. To determine structure-activity relationships, a collection of synthetic and natural product lipo-chitin oligosaccharides was assayed on Glycine soja. All biologically active lipo-chitin oligosaccharides induced both root hair deformation and nodule initiations on G. soja. The most active lipo-chitin oligosaccharides deformed root hairs at 10(-15) M and induced nodules at 1 ng of lipo-chitin oligosaccharide per spot inoculation. Plant responses demonstrate an interdependence of backbone length and the presence of substitutions on the reducing end. Lipo-chitin oligosaccharides containing four N-acetylglucosamine residues were active only without a reducing end modification, whereas lipo-chitin oligosaccharides containing five N-acetylglucosamine residues were active only with reducing end modification. The plant thus recognizes lipo-chitin oligosaccharides without reducing end substitutions despite the importance of these modifications for host range.

Carbohydrate Sequence↗
PubMed1993

The structures and biological activities of the lipo-oligosaccharide nodulation signals produced by type I and II strains of Bradyrhizobium japonicum.

Bradyrhizobium japonicum produces lipo-oligosaccharide signal molecules that induce deformation of root hairs and meristematic activity on soybeans. B. japonicum USDA135 (a Type I strain) produces modified chitin pentasaccharide molecules with either a terminal N-C16:0- or N-C18:1-glucosamine with and without an O-acetyl group at C-6 and with 2-O-methylfucose linked to C-6 of the reducing N-acetylglucosamine. An additional molecule has N-C16:1-glucosamine and no O-acetyl group. All of these molecules cause root hair deformation on Vicia sativa and Glycine soja. The C18:1-containing molecules were tested and found to induce meristem formation on G. soja. USDA61 (a Type II strain) produces eight additional molecules. Five have a carbamoyl group on the terminal N-acylglucosamine. Six have chitin tetrasaccharide backbones. Three have a terminal N-acyl-N-methylglucosaminosyl residue. In four molecules, the reducing-end N-acetylglucosamine is glycosidically linked to glycerol and has a branching fucosyl, rather than a 2-O-methylfucosyl, residue. One molecule has a terminal N-acylglucosamine that has both acetyl and carbamoyl groups (one each).

Antigens, Bacterial↗