HIV-related occlusive vasculitis.
Explore the source record for details and available documents.
Adult↗
Biomedical subjects
D B Roth
Publications and source records attributed to D B Roth.
External beam radiotherapy in retinoblastoma: tumor control and comparison of 2 techniques.
OBJECTIVE: To investigate eye conservation, local control, and complication rates among children with retinoblastoma treated with 2 different external beam radiotherapy (EBR) techniques. METHODS: Fifty-eight eyes in 42 patients received EBR as the primary treatment modality for retinoblastoma (median follow-up, 37 months). The EBR technique was relative lens-sparing (RLS) in 26 eyes and modified lateral beam (MLB) in 32 eyes. Both groups were comparable in Reese-Ellsworth retinoblastoma classification. If necessary, patients received focal salvage therapy. RESULTS: At 24 months, eye conservation rates were 88.5% and 89.1% among eyes treated with RLS and MLB, respectively (P = .40); tumor control rates without salvage therapy were 84.6% and 53.3% (P = .02), respectively. Among eyes with Reese-Ellsworth stage IV and V disease, eye conservation rates were 88%+/-8% and 83%+/-9% at 36 months in the RLS and MLB groups, respectively, and local tumor control rates were 81%+/-10% and 51%+/-12%. Percentages of eyes without cataract at 36 months were 83.1% and 63.0%, respectively (P = .40). Among patients observed for at least 18 months, midfacial hypoplasia developed in 38.5% and 29.4%, respectively (P = .70). CONCLUSIONS: The EBR technique was associated with high eye conservation and local control rates. Salvage therapy was performed significantly less frequently in the RLS group compared with the MLB group, and complication rates in both groups were similar.
Child, Preschool↗
Treatment of recurrent cytomegalovirus retinitis with the ganciclovir implant.
PURPOSE: To evaluate preoperative characteristics and outcome of the treatment of recurrent cytomegalovirus (CMV) retinitis with the ganciclovir implant. METHODS: Records of 54 patients with acquired immunodeficiency syndrome and active, previously treated CMV retinitis who received a ganciclovir implant in one (n = 31) or both (n = 23) eyes were reviewed. Entry criteria included prior insertion and removal of an indwelling catheter or failure to respond to tolerated doses of ganciclovir and foscarnet. Preoperative factors that might correlate with outcome were analyzed, including demographic factors, duration of human immunodeficiency virus disease and CMV retinitis, indications for surgery, prior anti-CMV treatment, and extent of retinitis. RESULTS: Forty-six patients completed 1 month of follow-up and were analyzed for outcome. Thirty-one (67.4%) had inactive retinitis at 1 month vs 15 (32.6%) with active retinitis, and they received a mean of 23.5 +/- 22.9 weeks of preoperative ganciclovir vs 58.0 +/- 52.0 weeks in patients with active retinitis (P = .003). Involvement of more than 25% of retinal area by CMV retinitis was also correlated with activity at 1 month (P < .001). Patients who received implants because of lack of venous access had a median time to progression of 8.0 +/- 3.0 months vs 2.0 +/- 1.2 months for patients who had inadequate response or intolerance to intravenous medication (P = .073). Patients with 6 months or less vs more than 6 months of preoperative ganciclovir treatment had progression at a median time of 8.0 +/- 1.7 months vs 2.0 +/- 0.3 months, respectively (P = .016). CONCLUSION: Longer duration of preoperative ganciclovir or larger area of CMV retinitis correlates with lower success of ganciclovir implant therapy for recurrent retinitis.
AIDS-Related Opportunistic Infections↗
Effect of potent antiretroviral therapy on recurrent cytomegalovirus retinitis treated with the ganciclovir implant.
PURPOSE: To determine the effect of highly active antiretroviral therapy on cytomegalovirus (CMV) retinitis treated with ganciclovir implants. METHODS: A retrospective cohort study was performed of 15 patients with recurrent CMV retinitis treated with the ganciclovir implant and highly active antiretroviral therapy (cases) and 38 patients with recurrent retinitis treated with ganciclovir implants before availability of improved antiretroviral therapy (controls). Progression was defined as occurrence of new lesions in the treated eye or advancement of the retinitis border by more than 750 microm. RESULTS: Cases and controls were statistically similar in age, ethnicity, and duration of acquired immunodeficiency syndrome (AIDS). Controls had received intravenous ganciclovir for 9.5 +/- 9.5 months vs 3.5 +/- 4.6 months in cases (P = .003). The mean (+/- SE) time to progression of retinitis after implantation of the device was 26.7 +/- 2.4 months (95% confidence interval, 22.1 to 31.3) in the cases receiving highly active antiretroviral therapy vs 6.2 +/- 0.9 months (95% confidence interval, 4.5 to 7.9) in the controls (P = .001). Multivariate analysis, adjusted for preoperative variables, confirmed a significantly prolonged time to progression in patients receiving highly active antiretroviral therapy (P = .0003). The odds ratio for progression in the cases vs controls was 0.034 (95% confidence interval, 0.003 to 0.350). Cases had higher CD4+ T-lymphocyte counts (P = .004) and longer survival (P < .001) than controls. CONCLUSION: Highly active antiretroviral therapy is associated with improved outcomes in patients with AIDS and recurrent CMV retinitis treated with the ganciclovir implant.
AIDS-Related Opportunistic Infections↗
Optic nerve avulsion from a golfing injury.
PURPOSE: To describe a patient with optic nerve avulsion after being struck in the eye with a golf club. METHODS: A 10-year-old male was hit in the left eye by a golf club. The patient underwent full ophthalmoscopic evaluation and neuroimaging. RESULTS: The patient had no light perception in the left eye when first seen. Avulsion of the optic nerve with vitreous hemorrhage was apparent on examination. Computed tomographic imaging of the brain and orbits revealed no abnormalities. CONCLUSIONS: Optic nerve avulsion from golf-related injury is more likely to occur when the impact site is between the globe and the orbital rim. Rupture of the globe is more likely to occur with direct impact to it.
Athletic Injuries↗
V(D)J recombination catalyzed by mutant RAG proteins lacking consensus DNA-PK phosphorylation sites.
The process of antigen receptor gene rearrangement, V(D)J recombination, involves DNA cleavage by the RAG-1 and RAG-2 proteins. Cleavage generates covalently sealed (hairpin) DNA ends, termed coding ends, which must be opened by an endonuclease prior to joining. Resolution of these hairpin ends requires the activity of the DNA-dependent protein kinase (DNA-PK), a protein kinase whose specific role is yet undetermined. It has been suggested that phosphorylation of one or both RAG proteins by DNA-PK is required to activate or recruit the hairpin-opening nuclease. Furthermore, very recent work has shown that RAG proteins themselves can open hairpins. These data raise the possibility that DNA-PK-mediated phosphorylation of the RAG proteins could regulate the hairpin opening reaction. To test this hypothesis, we constructed mutant versions of RAG-1 and RAG-2 in which all four DNA-PK consensus phosphorylation sites were removed by site-directed mutagenesis. Our data provide conclusive evidence that phosphorylation of these conserved serine/threonine residues is not required for hairpin opening or joining of V(D)J recombination intermediates.
Amino Acid Sequence↗
Intermolecular V(D)J recombination is prohibited specifically at the joining step.
V(D)J recombination, normally an intramolecular process, assembles immunoglobulin and T cell receptor genes from V, D, and J coding segments. Oncogenic chromosome translocations can result from aberrant rearrangements, such as occur in intermolecular V(D)J recombination. How this is normally prevented remains unclear; DNA cleavage, joining, or both could be impaired when the recombination signal sequences (RSS) are located in trans, on separate DNA molecules. Here, we show that both trans cleavage and joining of signal ends occur efficiently in vivo. Unexpectedly, trans joining of coding ends is severely impaired (100-to 1000-fold), indicating that protection against intermolecular V(D)J recombination is established at the joining step. These findings suggest a novel surveillance mechanism for eliminating cells containing aberrant V(D)J rearrangements.
Animals↗
What prevents intermolecular V(D)J recombination?
Explore the source record for details and available documents.
Animals↗
Roles of the "dispensable" portions of RAG-1 and RAG-2 in V(D)J recombination.
V(D)J recombination is initiated by introduction of site-specific double-stranded DNA breaks by the RAG-1 and RAG-2 proteins. The broken DNA ends are then joined by the cellular double-strand break repair machinery. Previous work has shown that truncated (core) versions of the RAG proteins can catalyze V(D)J recombination, although less efficiently than their full-length counterparts. It is not known whether truncating RAG-1 and/or RAG-2 affects the cleavage step or the joining step of recombination. Here we examine the effects of truncated RAG proteins on recombination intermediates and products. We found that while truncated RAG proteins generate lower levels of recombination products than their full-length counterparts, they consistently generate 10-fold higher levels of one class of recombination intermediates, termed signal ends. Our results suggest that this increase in signal ends does not result from increased cleavage, since levels of the corresponding intermediates, coding ends, are not elevated. Thus, removal of the "dispensable" regions of the RAG proteins impairs proper processing of recombination intermediates. Furthermore, we found that removal of portions of the dispensable regions of RAG-1 and RAG-2 affects the efficiency of product formation without altering the levels of recombination intermediates. Thus, these evolutionarily conserved sequences play multiple, important roles in V(D)J recombination.
DNA Nucleotidyltransferases↗
Analysis of variable (diversity) joining recombination in DNAdependent protein kinase (DNA-PK)-deficient mice reveals DNA-PK-independent pathways for both signal and coding joint formation.
Previous studies have suggested that ionizing radiation causes irreparable DNA double-strand breaks in mice and cell lines harboring mutations in any of the three subunits of DNA-dependent protein kinase (DNA-PK) (the catalytic subunit, DNA-PKcs, or one of the DNA-binding subunits, Ku70 or Ku86). In actuality, these mutants vary in their ability to resolve double-strand breaks generated during variable (diversity) joining [V(D)J] recombination. Mutant cell lines and mice with targeted deletions in Ku70 or Ku86 are severely compromised in their ability to form coding and signal joints, the products of V(D)J recombination. It is noteworthy, however, that severe combined immunodeficient (SCID) mice, which bear a nonnull mutation in DNA-PKcs, are substantially less impaired in forming signal joints than coding joints. The current view holds that the defective protein encoded by the murine SCID allele retains enough residual function to support signal joint formation. An alternative hypothesis proposes that DNA-PKcs and Ku perform different roles in V(D)J recombination, with DNA-PKcs required only for coding joint formation. To resolve this issue, we examined V(D)J recombination in DNA-PKcs-deficient (SLIP) mice. We found that the effects of this mutation on coding and signal joint formation are identical to the effects of the SCID mutation. Signal joints are formed at levels 10-fold lower than in wild type, and one-half of these joints are aberrant. These data are incompatible with the notion that signal joint formation in SCID mice results from residual DNA-PKcs function, and suggest a third possibility: that DNA-PKcs normally plays an important but nonessential role in signal joint formation.
Animals↗
Double-strand break repair in Ku86- and XRCC4-deficient cells.
The Ku86 and XRCC4 proteins perform critical but poorly understood functions in the repair of DNA double-strand breaks. Both Ku 86- and XRCC4-deficient cells exhibit profound radiosensitivity and severe defects in V(D)J recombination, including excessive deletions at recombinant junctions. Previous workers have suggested that these phenomena may reflect defects in joining of the broken DNA ends or in protection of the ends from nucleases. However, end joining in XRCC4-deficient cells has not been examined. Here we show that joining of both matched and mismatched DNA ends occurs efficiently in XRCC4-deficient cells. Furthermore, analysis of junctions shows that XRCC4 is not required to protect the ends from degradation. However, nucleotide sequence analysis of junctions derived from joining of mismatched DNA ends in XRCC4-deficient cells revealed a strong preference for a junction containing a 7 nt homology. Similar results were obtained in Ku86-deficient cells. These data suggest that in the absence of XRCC4 or Ku86, joining is assisted by base pairing interactions, supporting the hypothesis that these proteins may participate in aligning or stabilizing intermediates in end joining.
Animals↗
VDJ recombination: a transposase goes to work.
Explore the source record for details and available documents.
DNA Nucleotidyltransferases↗
V(D)J recombination intermediates and non-standard products in XRCC4-deficient cells.
V(D)J recombination assembles immunoglobulin (Ig) and T cell receptor (TCR) gene segments during lymphocyte development. Recombination is initiated by the RAG-1 and RAG-2 proteins, which introduce double-stranded DNA breaks (DSB) adjacent to the Ig and TCR gene segments. The broken ends are joined by the DSB repair machinery, which includes the XRCC4 protein. While XRCC4 is essential for both DSB repair and V(D)J recombination, the functions of this protein remain enigmatic. Because the rare V(D)J recombination products isolated from XRCC4-deficient cells generally show evidence of excessive nucleotide loss, it was hypothesized that XRCC4 may function to protect broken DNA ends. Here we report the first examination of V(D)J recombination intermediates in XRCC4-deficient cells. We found that both types of intermediates, signal ends and coding ends, are abundant in the absence of XRCC4. Furthermore, the signal ends are full length. We also showed that alternative V(D)J recombination products, hybrid joints, form with normal efficiency and without excessive deletion in XRCC4-deficient cells. These data indicate that impaired formation of V(D)J recombination products in XRCC4-deficient cells does not result from excessive degradation of recombination intermediates. Potential roles of XRCC4 in the joining reaction are discussed.
Animals↗
Normal junctional diversification of immune receptors in p53-deficient mice.
One of the strategies that the immune system utilizes to generate Ab and TCR diversity is programmed imprecision of coding joint formation. This is accomplished by both nucleotide loss and random nucleotide addition (N segments) to the termini of immune receptor coding segments before resolution. Although it has been known for more than a decade that terminal deoxynucleotidyl transferase is the enzyme responsible for N segment addition, the enzymes responsible for nucleotide loss have not been identified. Recently, the p53 tumor suppressor protein was shown to have an intrinsic exonuclease activity; we reasoned that p53 as an exonuclease might be responsible for coding end processing during V(D)J recombination. Thus, we examined nucleotide loss from Ig and TCR-beta coding joints in mice lacking p53. We find no significant difference in the degree of nucleotide loss in coding joints isolated from these animals as compared with littermate controls. Thus, we conclude that p53 does not play a role in removal of nucleotides from coding termini during V(D)J recombination. Additionally, recent evidence has surfaced suggesting that p53 may play an important checkpoint role in early thymocyte differentiation. More specifically, it has been suggested that p53 is required to prevent thymocytes from maturing to the double-positive stage in the absence of a functionally rearranged TCR-beta allele. Our data suggest that TCR-beta selection is not affected in p53-deficient, V(D)J rearrangement-proficient mice.
Animals↗
Initiation of V(D)J recombination in vivo: role of recombination signal sequences in formation of single and paired double-strand breaks.
In V(D)J recombination, double-strand breaks (DSBs) are introduced at recombination signal sequences (RSSs) which consist of three distinct elements: a heptamer, a 12 or 23 nucleotide spacer and a nonamer. Efficient DSB formation requires a 12/23 RSS pair and occurs at both RSS in a temporally coupled fashion (coupled cleavage). It remains unknown which RSS elements are important for coupled cleavage. Furthermore, it has not been established whether some RSS components are critical only for cleavage in cis, with others mainly promoting cleavage in trans at the partner RSS. We investigated these questions by analyzing the effects of RSS mutations on the formation of DSBs in vivo. The abundance of DSBs in cis (at the mutant RSS) and in trans (at the consensus RSS) was determined using an established ligation-mediated PCR assay. We also developed a Southern blotting approach that allows the first direct measurement of dual and single RSS cleavage in vivo. Our results demonstrate that the heptamer, spacer and nonamer elements are all required for coupled cleavage in vivo. These studies also provide evidence for cleavage events involving a single RSS both in mutant substrates and in substrates containing a consensus 12/23 RSS pair.
DNA↗
Vitreous surgery for chronic macular holes.
OBJECTIVE: The purpose of the study is to compare the results of vitreous surgery for a group of patients with chronic macular holes with a group of patients with acute-onset macular holes undergoing identical surgery. DESIGN: A case-control study design was used. PARTICIPANTS: The duration of symptoms of visual loss due to macular holes was greater than 1 year's duration in 11 eyes in each group consecutively operated on within a few days. INTERVENTION: All patients underwent macular hole surgery. MAIN OUTCOME MEASURES: Ophthalmoscopic resolution of the macular hole, improvement of 2 lines of visual acuity or greater, improvement in mean and median visual acuity, and rate of 20/40 or greater final visual acuity. RESULTS: The hole resolved in 9 of 11 eyes in the chronic group and 10 of 11 eyes in the acute group. The mean (median) preoperative visual acuity was 20/151 (20/200) in the chronic group and 20/139 (20/200) in the acute group. The 3-month mean (median) postoperative visual acuity was 20/85 (20/80) in the chronic group and 20/62 (20/63) in the acute group. The final mean (median) postoperative visual acuity was 20/96 (20/ 100) in the chronic group and 20/48 (20/50) in the acute group (P = 0.022). The mean interval to final follow-up examination was 70 weeks for the chronic group and 44 weeks for the acute group. Five (45%) of 11 eyes with chronic holes and 8 (73%) of 11 eyes in the acute group had a final visual acuity of 2 lines or better than the preoperative visual acuity. Cataract extraction had been performed by the final follow-up examination in 7 chronic eyes (64%) and 2 acute eyes (18%). CONCLUSIONS: Chronic macular holes have a similar anatomic success rate, but a poorer visual prognosis than acute holes after macular hole surgery. Vitreous surgery benefits some patients with idiopathic macular holes of greater than 1 year's duration.
Acute Disease↗
Growth retardation and leaky SCID phenotype of Ku70-deficient mice.
Ku70, Ku80, and DNA-PKcs are subunits of the DNA-dependent protein kinase (DNA-PK), an enzyme implicated in DNA double-stranded break repair and V(D)J recombination. Our Ku70-deficient mice were about 50% the size of control littermates, and their fibroblasts were ionizing radiation sensitive and displayed premature senescence associated with the accumulation of nondividing cells. Ku70-deficient mice lacked mature B cells or serum immunoglobulin but, unexpectedly, reproducibly developed small populations of thymic and peripheral alpha/beta T lineage cells and had a significant incidence of thymic lymphomas. In association with B and T cell developmental defects, Ku70-deficient cells were severely impaired for joining of V(D)J coding and recombination signal sequences. These unanticipated features of the Ku70-deficient phenotype with respect to lymphocyte development and V(D)J recombination may reflect differential functions of the three DNA-PK components.
Animals↗
V(D)J recombination in Ku86-deficient mice: distinct effects on coding, signal, and hybrid joint formation.
Ku, a heterodimer of 70 and 86 kDa subunits, plays a critical but poorly understood role in V(D)J recombination. Although Ku86-deficient mice are defective in coding and signal joint formation, rare recombination products have been detected by PCR. Here, we report nucleotide sequences of 99 junctions from Ku86-deficient mice. Over 90% of the coding joints, but not signal or hybrid joints, exhibit short sequence homologies, indicating that homology is required to join coding ends in the absence of Ku86. Our results suggest that Ku86 may normally have distinct functions in the formation of these different types of junctions. Furthermore, Ku86(-/-) joints are unexpectedly devoid of N-region diversity, suggesting a novel role for Ku in the addition of N nucleotides by terminal deoxynucleotidyl transferase.
Animals↗