Etoposide causes illegitimate V(D)J recombination in human lymphoid leukemic cells

Etoposide is one of the most widely used antineoplastics. Unfortunately, the same treatment schedules associated with impressive efficacy are associated with an increased risk of secondary acute myeloid leukemia (AML), which has prompted its withdrawal from some treatment regimens, thereby potentially compromising efficacy against the original tumor. Because etoposide-associated AML is characterized by site-specific illegitimate DNA recombination, we studied whether etoposide could directly cause site-specific deletions of exons 2 and 3 in the hprt gene. Human lymphoid CCRF-CEM cells were treated with etoposide for 4 hours, and DNA was isolated after subculturing. The deletion of exons 2 and 3 from hprt was assayed by a quantitative polymerase chain reaction (PCR) method. In the absence of etoposide treatment, the frequency of deletions of exons 2 and 3 was very low (5.05 x 10(-8)). After exposure to 10 mumol/ L etoposide, the frequency of the exon 2 + 3 deletion was increased immediately after and at 24 hours after etoposide treatment (65 to 89 x 10(-8)) and increased to higher levels (128 to 173 x 10(-8)) after 2 and 6 days of subculture (P < .001 overall). The frequency of the exon 2 + 3 deletion assessed at 6 days of subculture after 4 hours of 0, 0.25, 1, 2.5, 5, and 10 mumol/L etoposide treatment increased with etoposide concentration, ie, 5.05 x 10(-8), 89.2 x 10(-8), 108 x 10(-8), 142 x 10(-8), 163 x 10(-8), and 173 x 10(-8), respectively (P < .0001). Sequencing of a subset of amplified products confirmed the presence of DNA sequences at the breakpoints consistent with V(D)J recombination. By contrast, exon 2 + 3 deletions after etoposide treatment in the myeloid cell lines KG-1A and K562 showed no evidence of V(D)J recombinase in their genesis. We conclude that etoposide can induce the illegitimate site-specific action of V(D)J recombinase on an unnatural DNA substrate after a single treatment in human lymphoid cells.     

Modified heparin-bonded catheter for cannulation of the coronary sinus from the femoral vein

Serial sampling from the coronary sinus is an attractive technique for drawing blood samples to be used in the characterization of procoagulant activity during coronary interventions. We have developed a modified Simmons catheter for rapid cannulation of the coronary sinus from the femoral approach. The catheter design incorporates heparin bonding and distal side-holes to minimize blood sampling artifacts. Coronary sinus cannulation was performed via the femoral approach in 186 patients by use of a multipurpose catheter (n = 8), an unmodified Simmons I or II catheter (n = 64), or the modified Simmons catheter (n = 114). The coronary sinus was cannulated successfully with the modified Simmons catheter in 97% of patients; the success rate with the unmodified Simmons II catheter was 87% (P = 0.02). The modified Simmons catheter represents an improved technique for cannulation of the coronary sinus from the femoral vein. © Wiley-Liss, Inc.     

Antiviral Activity of Aloe Extracts against Cytomegalovirus

Substances extracted from the leaves of aloe plants have been reported to have antiviral effects against enveloped viruses in in vitro test systems. In the present studies, we have assessed the antiviral activity of partially purified extracts prepared from the gel portion of leaves of Aloe barbadensis Miller against human cytomegalovirus (CMV) by plaque inhibition tests (PIT), flow cytometry and morphometry assays. Six test extracts of gel filet portions of aloe leaves were prepared; i.e. R1 from immature leaves harvested in the early summer, S1 from mature leaves harvested in the autumn, F1 from S1 after freezing at −20°C, and R2, S2 and F2 which were ethanol treated extracts of R1, S1 and F1, respectively. When test aloe extracts were added at various concentrations during the course of infection with CMV, R1, S1 and F2 at concentrations of 10⁻¹ inhibited plaque formation. The addition of S1 to the medium between 12 and 36 h after initiation of CMV infection, a time of high DNA synthesis, caused the most effective plaque inhibition. Flow cytometric and morphometric analyses revealed no significant differences in aloe extract treated, CMV infected cells compared with non-aloe treated CMV infected control cells. The results suggest that a major mechanism of inhibition of CMV infection by aloe extracts is through interference with DNA synthesis.     

Mandibular rescue: Application of the ALT fascia free flap to arrest osteoradionecrosis of the mandible

ObjectivesTo evaluate the use of the anterolateral thigh fascia free flap for use in neovascularization of mandibular bone in moderate osteoradionecrosis (ORN). All patients had ORN secondary to prior radiation therapy that was not severe enough to warrant segmental resection and reconstruction.Study designCase series.SettingTertiary medical center.MethodsIRB approval was obtained, and a retrospective chart review performed of all mandibular rescue procedures performed from 2011 to 2014. Patients with a minimum of two years of follow-up were included in the study.ResultsAll surgeries were performed by the senior surgeon (MF). Eight patients underwent the mandibular rescue procedure with resolution of pain and return to oral feeding in all patients, and no evidence of ORN progression on follow-up imaging. A total of 9 ALT free flaps were performed (one patient had 2 surgeries). Gender was distributed evenly (4 female/4 male). The average age was 66 (58-78), average length of hospitalization was 2.8 days (1–7), and average follow-up was 46.5 months (25–63).ConclusionsThe mandibular rescue procedure is a novel technique using the ALT fascia lata free flap to provide coverage and nutrient blood flow to mandible devascularized secondary to radiation therapy. The flap provides the advantages of low morbidity, ease of harvest, two-team approach to ablation and reconstruction, and quick recovery resulting in ‘short-stay’ free flap surgery. Although conclusions must be tempered in this small case series, our early clinical experience shows the ALT fascia lata flap holds promise in halting the destructive progression of ORN that is not yet advanced enough to require a segmental resection and reconstruction.     

The influence of body size on the pharmacodynamic and pharmacokinetic response to clopidogrel and prasugrel: A retrospective analysis of the FEATHER study

Introduction

Patients treated with clopidogrel who have higher body size exhibit greater platelet reactivity than patients with lower body size. In a retrospective analysis of the FEATHER trial, we examined the relationship between platelet response to thienopyridines clopidogrel 75 mg (Clop-75), prasugrel 5 mg (Pras-5), and prasugrel 10 mg (Pras-10) using 3 body size indices: body weight (BW), body mass index (BMI), and body surface area (BSA). Relationships were assessed as continuous variables and as 4 incremental body size groups.

Materials and Methods

Aspirin-treated patients with stable coronary artery disease (N = 72) and a BW range of 45-134 kg received Clop-75, Pras-5, and Pras-10 in a 3-period, blinded, cross-over study. Platelet assays included maximum platelet aggregation (MPA) to 20 μM ADP by light transmission aggregometry, VerifyNow-P2Y12 reaction units (PRU), and vasodilator-associated stimulated phosphoprotein (VASP) phosphorylation platelet reactivity index (PRI). Exposure to active metabolites (AMs) was also assessed.

Results

Body size was a determinant of AM exposure and residual platelet reactivity regardless of type and dose of thienopyridine. BW and BSA demonstrated marginally stronger correlations with platelet reactivity; VASP-PRI demonstrated a stronger correlation with the body size than the other tests. Correlation coefficients ranged from a high of 0.64 (BW vs. PRI on Pras-5) to a low of 0.34 (BMI vs. MPA on Pras-10), but all were statistically significant (p < 0.01).

Conclusions

Using a comprehensive selection of body size indices, AM exposures, platelet function tests, and thienopyridine doses, we demonstrated a consistent inverse relationship between body size and response to clopidogrel and prasugrel.     

Fostering Children's Participation in Disaster Risk Reduction Through Play:A Case Study of LEGO and Minecraft

This article focuses on children's participation in disaster risk reduction.It draws on a 2018 study done in New Zealand with 33 school children who conducted p...     

Response of X and Y cat retinal ganglion cells to moving stimuli

Summary Single optic tract fibers in the cat were classified as X or Y cells by a contrast reversal stimulus. A slit of light was then moved across the receptive field at velocities from 10–1000 ° /s. The preferred velocity was that velocity which elicited the strongest response from the cell. The maximum velocity was the highest velocity target to which a cell could respond. Y cells as a group both preferred and could follow faster targets than X cells, and were more broadly tuned to the preferred velocity.This study was supported by Public Health Service Grant EY 00701 and NEI Grant EY 00376