Chronic postoperative endophthalmitis secondary to Ochrobactrum anthropi.
Explore the source record for details and available documents.
Anti-Bacterial Agents↗
Biomedical subjects
K C Nelson
Publications and source records attributed to K C Nelson.
Oxidative damage and protection of the RPE.
This review provides a model for the role of oxidative stress in the etiology of age-related macular degeneration (AMD). Epidemiological studies of diet, environmental and behavioral risk factors suggest that oxidative stress is a contributing factor of AMD. Pathological studies indicate that damage to the retinal pigment epithelium (RPE) is an early event in AMD. In vitro studies show that oxidant treated RPE cells undergo apoptosis, a possible mechanism by which RPE cells are lost during early phase of AMD. The main target of oxidative injury seems to be mitochondria, an organelle known to accumulate genomic damages in other postmitotic tissues during aging. The thiol antioxidant GSH and its amino acid precursors protect RPE cells from oxidant-induced apoptosis. Similar protection occurs with dietary enzyme inducers which increase GSH synthesis. These results indicate that therapeutic or nutritional intervention to enhance the GSH antioxidant capacity of RPE may provide an effective way to prevent or treat AMD.
Aging↗
A protein phosphatase methylesterase (PME-1) is one of several novel proteins stably associating with two inactive mutants of protein phosphatase 2A.
Carboxymethylation of proteins is a highly conserved means of regulation in eukaryotic cells. The protein phosphatase 2A (PP2A) catalytic (C) subunit is reversibly methylated at its carboxyl terminus by specific methyltransferase and methylesterase enzymes which have been purified, but not cloned. Carboxymethylation affects PP2A activity and varies during the cell cycle. Here, we report that substitution of glutamine for either of two putative active site histidines in the PP2A C subunit results in inactivation of PP2A and formation of stable complexes between PP2A and several cellular proteins. One of these cellular proteins, herein named protein phosphatase methylesterase-1 (PME-1), was purified and microsequenced, and its cDNA was cloned. PME-1 is conserved from yeast to human and contains a motif found in lipases having a catalytic triad-activated serine as their active site nucleophile. Bacterially expressed PME-1 demethylated PP2A C subunit in vitro, and okadaic acid, a known inhibitor of the PP2A methylesterase, inhibited this reaction. To our knowledge, PME-1 represents the first mammalian protein methylesterase to be cloned. Several lines of evidence indicate that, although there appears to be a role for C subunit carboxyl-terminal amino acids in PME-1 binding, amino acids other than those at the extreme carboxyl terminus of the C subunit also play an important role in PME-1 binding to a catalytically inactive mutant.
3T3 Cells↗
Oxidant-induced apoptosis in cultured human retinal pigment epithelial cells.
PURPOSE: To determine the mechanism of oxidant-induced cell death in cultured human retinal pigment epithelium (hRPE). METHODS: Cultured hRPE cells were treated with different concentrations of a chemical oxidant, t-butylhydroperoxide (tBH), for different periods of time. Apoptosis was determined with terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling (TUNEL) and flow cytometry. Mitochondrial membrane potential (mtdelta psi) was measured by rhodamine 123 staining and subsequent flow cytometry. Release of mitochondrial cytochrome c (cyt c) and cleavage of procaspase 3 and caspase substrates were determined by western blot analysis. RESULTS: t-Butylhydroperoxide caused time- and dose-dependent activation of apoptosis in hRPE, indicated by characteristic morphologic changes; TUNEL-positive labeling; phosphatidylserine (PS) exposure; and procaspase 3, poly(ADP-ribose)polymerase, lamin, and tubulin cleavage. An early decrease of mtdelta psi was observed before caspase activation, together with the release of mitochondrial cyt c. CONCLUSIONS: Results indicate that tBH can induce apoptosis in hRPE, probably by triggering the mitochondrial permeability transition, which results in swelling and release of mitochondrial intermembrane proteins.
Aged↗
Effect of dietary inducer dimethylfumarate on glutathione in cultured human retinal pigment epithelial cells.
PURPOSE: To determine the effect of dimethylfumarate (DMF), an inducer of glutathione (GSH)-dependent detoxification, on intracellular GSH levels in cultured human retinal pigment epithelium (hRPE) cells, its mechanism of action, and its effect on hRPE cells subjected to oxidative injury. METHODS: Established hRPE cell lines were treated with DMF and assayed by high-pressure liquid chromatography for intracellular and extracellular GSH levels. Quantification of gamma-glutamylcysteine synthetase (GLCL) was determined through northern and western blot analyses, and activity was measured. Effects of pretreatment with DMF on GSH redox status of hRPE cells was determined. Sensitivity of hRPE cells to oxidative stress was determined using tert-butylhydroperoxide as the oxidative agent. RESULTS: Dimethylfumarate caused a transient decrease followed by a significant increase in intracellular GSH. Glutathione increased maximally at 24 hours with 100 to 200 microM DMF. The initial decrease could be accounted for by the formation of a DMF-GSH conjugate. Dimethylfumarate treatment increased the steady state mRNA expression of the regulatory subunit of GLCL, but no increase was seen for the catalytic subunit. However, protein levels were increased for both, and the catalytic activity of GLCL was also increased. Whereas the initial decrease in GSH made hRPE cells more susceptible to oxidative damage, pretreatment with DMF under conditions that increased intracellular GSH protected hRPE cells against oxidative damage. CONCLUSIONS: These results suggest a means by which the antioxidant capability of hRPE may be augmented without direct antioxidant supplementation. Specifically, a dietary compound that conjugates with GSH can induce GSH synthesis, increase GSH concentration, and improve protection by GSH-dependent detoxification pathways in hRPE. However, the early depletion of GSH before stimulated synthesis necessitates caution in prevention strategies using dietary inducers.
Aminoacyltransferases↗
Familial multiple blue nevi.
The blue nevus most commonly presents as a solitary blue nodule. Four histologic variants of blue nevus have been described. Rarely, multiple blue nevi blue nevi may occur in a single person. Only 1 case of familial multiple blue nevi has been described.
Adolescent↗
The division of neuronal progenitor cells during migration in the neonatal mammalian forebrain.
In the mammalian forebrain most neurons originate from proliferating cells in the ventricular zone lining the lateral ventricles. These neurons become postmitotic before they undergo migration to their final destinations. In this study we examined the proliferative and migratory properties of cells destined for the olfactory bulb that arise postnatally from progenitor cells situated at the anterior extent of the subventricular zone (SVZa). The SVZa-derived cells migrate along a stereotypical pathway to the olfactory bulb where they become interneurons. Using lineage tracers and the cell proliferation marker BrdU, we have demonstrated that SVZa-derived cells in the rat retain the capacity for division after migrating away from their initial site of generation. These cells also express a neuron-specific tubulin, recognized by the antibody TuJ1. These results suggest that, unlike other immature neurons, these SVZa-derived cells have made a commitment to become neurons before becoming postmitotic.
Animals↗
Wound strength in abdominal incisions: a comparison of two continuous mass closure techniques in rats.
Explore the source record for details and available documents.
Abdominal Muscles↗
The relationship between isometric contraction durations and improvement in shoulder joint range of motion.
Proprioceptive Neuromuscular Facilitation (PNF) flexibility techniques are now being used in health and sports related activities, yet it is unclear as to the relationship between various isometric contraction time increments and joint range of motion. The purpose of this study, therefore, was to determine the relationship between a three-second, six-second, and ten-second maximum voluntary isometric contraction (MVIC). A modified PNF procedure referred to as the slow-reversal-hold-relax (SRHR) flexibility technique was employed in the investigation. It was hypothesized that longer MVIC time increments used with the SRHR flexibility technique would provide greater range of motion (ROM). Specifically, the ten-second MVIC was believed to be superior to the six-second and three-second MVIC. Furthermore, it was hypothesized that the six-second MVIC was superior to the three-second MVIC. Sixty subjects, ages 14-57 were randomly assigned to one of three treatment groups. Using a Leighton Flexometer, acute internal rotation of the shoulder joint was measured in degrees for six trials. Three passive stretch trials served as the baseline measurement for each subject (trials 1-3). The SRHR flexibility technique was used as the treatment for trials 4-6. A sixty-second rest interval common to clinical settings was integrated between each trial. The hypothesis was not accepted that a positive correlation existed between increased MVIC time and greater ROM.
Adolescent↗