|Differential modification of phosducin protein in degenerating rd1 retina is associated with constitutively active Ca2+/calmodulin kinase II in rod outer segments. |
Hauck, SM; Ekström, PA; Ahuja-Jensen, P; Suppmann, S; Paquet-Durand, F; van Veen, T; Ueffing, M
Molecular & cellular proteomics : MCP
Retinitis pigmentosa comprises a heterogeneous group of incurable progressive blinding diseases with unknown pathogenic mechanisms. The retinal degeneration 1 (rd1) mouse is a retinitis pigmentosa model that carries a mutation in a rod photoreceptor-specific phosphodiesterase gene, leading to rapid degeneration of these cells. Elucidation of the molecular differences between rd1 and healthy retinae is crucial for explaining this degeneration and could assist in suggesting novel therapies. Here we used high resolution proteomics to compare the proteomes of the rd1 mouse retina and its congenic, wild-type counterpart at postnatal day 11 when photoreceptor death is profound. Over 3000 protein spots were consistently resolved by two-dimensional gel electrophoresis and subjected to a rigorous filtering procedure involving computer-based spot analyses. Five proteins were accepted as being differentially expressed in the rd1 model and subsequently identified by mass spectrometry. The difference in one such protein, phosducin, related to an altered modification pattern in the rd1 retina rather than to changed expression levels. Additional experiments showed phosducin in healthy retinae to be highly phosphorylated in the dark- but not in the light-adapted phase. In contrast, rd1 phosducin was highly phosphorylated irrespective of light status, indicating a dysfunctional rd1 light/dark response. The increased rd1 phosducin phosphorylation coincided with increased activation of calcium/calmodulin-activated protein kinase II, which is known to utilize phosducin as a substrate. Given the increased rod calcium levels present in the rd1 mutation, calcium-evoked overactivation of this kinase may be an early and long sought for step in events leading to photoreceptor degeneration in the rd1 mouse.
|Detection of precytopathic effect of enteroviruses in clinical specimens by centrifugation-enhanced antigen detection. |
S M Lipson, K David, F Shaikh, L Qian
Journal of clinical microbiology
Rapid enterovirus detection is important for decisions about antibiotic administration and length of hospital stay. The efficacy of rapid antigen detection-cell culture amplification (Ag-CCA) was evaluated with monoclonal antibodies (MAbs) 5-D8/1 (DAKO) and Pan-Enterovirus clone 2E11 (Chemicon) with 10 poliovirus, echovirus, and coxsackievirus type A and B stock isolates and College of American Pathologists check samples. By using Ag-CCA technology, MAb 2E11 was more sensitive than 5-D8/1 at detecting a greater number of stock isolates at or past tube (cytopathic effect [CPE]) culture (TC) end points. The efficacy of Ag-CCA in the clinical setting was subsequently confirmed with 273 consecutively freshly collected nasopharyngeal aspirate or swab specimens, rectal swab, and cerebrospinal fluid specimens during the 1999 enterovirus season. All specimens were tested by Ag-CCA in parallel with rhesus monkey kidney (RhMk), MRC-5, and A549 conventional TCs. Approximately 60% of field specimens were additionally tested with Hep-2 and HNK conventional TCs. Sixty-two percent of the clinical specimens tested were Ag-CCA positive after 48 h. Among 51 isolates, the mean time to CPE or culture confirmation was 5.5 days (range, 2 to 18 days). After 48 h, Ag-CCA achieved sensitivity, specificity, and positive and negative predictive values of 62, 100, 100, and 93%, respectively. During the same period, TC-CPE displayed test parameters of 12, 100, 100, and 85%, respectively. After 5 days, the sensitivity and specificity of Ag-CCA increased to 92 and 98%, respectively. Within the same period, isolation attained sensitivity and specificity of 52 and 100%, respectively. Although Ag-CCA displayed slightly reduced sensitivity and reduced specificity compared with conventional cell culture after 14 days, the markedly superior 48-h enterovirus Ag-CCA detection rate supports incorporation of this assay into the routine clinical setting.Full Text Article