Effects of the paralysis tick, Ixodes holocyclus, on the electrocardiogram of the Spectacled Flying Fox, Pteropus conspicillatus

Objective To evaluate cardiac electrical function in the Spectacled Flying Fox (bat) infested with Ixodes holocyclus. Design Prospective clinical investigation of bats treated for naturally occurring tick toxicity. Procedure ECGs were performed on bats with tick toxicity (n = 33), bats that recovered slowly (n = 5) and normally (n = 5) following treatment for tick toxicity, and on normal bats with no history of tick toxicity (n = 9). Results Bats with tick toxicity had significantly prolonged corrected QT intervals, bradycardia and rhythm disturbances which included sinus bradydysrhythmia, atrial standstill, ventricular premature complexes, and idioventricular bradydysrhythmia. Conclusions The QT prolongation observed on ECG traces of bats with tick toxicity reflected delayed ventricular repolarisation and predisposed to polymorphic ventricular tachycardia and sudden cardiac death in response to sympathetic stimulation. The inability to document ventricular tachycardia in bats shortly before death from tick toxicity may be explained by a lack of sympathetic responsiveness attributable to the unique parasympathetic innervation of the bat heart, or hypothermiainduced catecholamine receptor down-regulation. Bradycardia and rhythm disturbances may be attributable to hypothermia.

A Comparison of Radiation Dose Between Standard and 3D Angiography in Congenital Heart Disease

Background: The use of three-dimensional rotational angiography (3D-RA) to assess patients with congenital heart diseases appears to be a promising technique despite the scarce literature available. Objectives: The objective of this study was to describe our initial experience with 3D-RA and to compare its radiation dose to that of standard two-dimensional angiography (2D-SA). Methods: Between September 2011 and April 2012, 18 patients underwent simultaneous 3D-RA and 2D-SA during diagnostic cardiac catheterization. Radiation dose was assessed using the dose-area-product (DAP). Results: The median patient age and weight were 12.5 years and 47.5 Kg, respectively. The median DAP of each 3D-RA acquisition was 1093µGy.m2 and 190µGy.m2 for each 2D-SA acquisition (p<0.01). In patients weighing more than 45Kg (n=7), this difference was attenuated but still significant (1525 µGy.m2 vs.413µGy.m2, p=0.01). No difference was found between one 3D-RA and three 2D-SA (1525µGy.m2 vs.1238 µGy.m2, p = 0.575) in this population. This difference was significantly higher in patients weighing less than 45Kg (n=9) (713µGy.m2 vs.81µGy.m2, P = 0.008), even when comparing one 3D-RA with three 2D-SA (242µGy.m2, respectively, p<0.008). 3D-RA was extremely useful for the assessment of conduits of univentricular hearts, tortuous branches of the pulmonary artery, and aorta relative to 2D-SA acquisitions. Conclusions: The radiation dose of 3D-RA used in our institution was higher than those previously reported in the literature and this difference was more evident in children. This type of assessment is of paramount importance when starting to perform 3D-RA.

Extremity and eye lens doses in interventional radiology and cardiology procedures: first results of the ORAMED project.

The main objective of WP1 of the ORAMED (Optimization of RAdiation protection for MEDical staff) project is to obtain a set of standardised data on extremity and eye lens doses for staff in interventional radiology (IR) and cardiology (IC) and to optimise staff protection. A coordinated measurement program in different hospitals in Europe will help towards this direction. This study aims at analysing the first results of the measurement campaign performed in IR and IC procedures in 34 European hospitals. The highest doses were found for pacemakers, renal angioplasties and embolisations. Left finger and wrist seem to receive the highest extremity doses, while the highest eye lens doses are measured during embolisations. Finally, it was concluded that it is difficult to find a general correlation between kerma area product and extremity or eye lens doses.

Melanopsin as a sleep modulator: circadian gating of the direct effects of light on sleep and altered sleep homeostasis in Opn4(-/-) mice.

Light influences sleep and alertness either indirectly through a well-characterized circadian pathway or directly through yet poorly understood mechanisms. Melanopsin (Opn4) is a retinal photopigment crucial for conveying nonvisual light information to the brain. Through extensive characterization of sleep and the electrocorticogram (ECoG) in melanopsin-deficient (Opn4(-/-)) mice under various light-dark (LD) schedules, we assessed the role of melanopsin in mediating the effects of light on sleep and ECoG activity. In control mice, a light pulse given during the habitual dark period readily induced sleep, whereas a dark pulse given during the habitual light period induced waking with pronounced theta (7-10 Hz) and gamma (40-70 Hz) activity, the ECoG correlates of alertness. In contrast, light failed to induce sleep in Opn4(-/-) mice, and the dark-pulse-induced increase in theta and gamma activity was delayed. A 24-h recording under a LD 1-hratio1-h schedule revealed that the failure to respond to light in Opn4(-/-) mice was restricted to the subjective dark period. Light induced c-Fos immunoreactivity in the suprachiasmatic nuclei (SCN) and in sleep-active ventrolateral preoptic (VLPO) neurons was importantly reduced in Opn4(-/-) mice, implicating both sleep-regulatory structures in the melanopsin-mediated effects of light. In addition to these acute light effects, Opn4(-/-) mice slept 1 h less during the 12-h light period of a LD 12ratio12 schedule owing to a lengthening of waking bouts. Despite this reduction in sleep time, ECoG delta power, a marker of sleep need, was decreased in Opn4(-/-) mice for most of the (subjective) dark period. Delta power reached after a 6-h sleep deprivation was similarly reduced in Opn4(-/-) mice. In mice, melanopsin's contribution to the direct effects of light on sleep is limited to the dark or active period, suggesting that at this circadian phase, melanopsin compensates for circadian variations in the photo sensitivity of other light-encoding pathways such as rod and cones. Our study, furthermore, demonstrates that lack of melanopsin alters sleep homeostasis. These findings call for a reevaluation of the role of light on mammalian physiology and behavior.

Protection from radiation-induced colitis requires MHC class II antigen expression by cells of hemopoietic origin.

Ulcerative colitis, an inflammatory bowel disease, is believed to result from a breakdown of dominant tolerance mechanisms that normally control intestinal immunity. Although CD4+ T lymphocyte subpopulations and expression of MHC class II molecules have been shown to play a role in the pathogenesis of the disease, the nature of the responsible mechanisms remains unclear. In this paper we describe a novel mouse model for inflammatory bowel disease, radiation-induced colitis, that occurs with complete penetrance 6-8 wk postinduction. A combination of high dose gamma-irradiation and lack of MHC class II expression on cells of hemopoietic origin results in development of colitis in C57BL/6 mice. Because of its versatility (due to susceptibility of mice of the widely genetically manipulated C57BL/6 background), high reproducibility, and 100% penetrance, radiation-induced colitis will be a useful mouse model for colitis and a significant tool to study dominant immunological tolerance mechanisms. Moreover, our data imply that tolerization to enteric Ags requires MHC class II mediated presentation by APC of hemopoietic origin.

Early and late skin reactions to radiotherapy for breast cancer and their correlation with radiation-induced DNA damage in lymphocytes

INTRODUCTION Radiotherapy outcomes might be further improved by a greater understanding of the individual variations in normal tissue reactions that determine tolerance. Most published studies on radiation toxicity have been performed retrospectively. Our prospective study was launched in 1996 to measure the in vitro radiosensitivity of peripheral blood lymphocytes before treatment with radical radiotherapy in patients with breast cancer, and to assess the early and the late radiation skin side effects in the same group of patients. We prospectively recruited consecutive breast cancer patients receiving radiation therapy after breast surgery. To evaluate whether early and late side effects of radiotherapy can be predicted by the assay, a study was conducted of the association between the results of in vitro radiosensitivity tests and acute and late adverse radiation effects. METHODS Intrinsic molecular radiosensitivity was measured by using an initial radiation-induced DNA damage assay on lymphocytes obtained from breast cancer patients before radiotherapy. Acute reactions were assessed in 108 of these patients on the last treatment day. Late morbidity was assessed after 7 years of follow-up in some of these patients. The Radiation Therapy Oncology Group (RTOG) morbidity score system was used for both assessments. RESULTS Radiosensitivity values obtained using the in vitro test showed no relation with the acute or late adverse skin reactions observed. There was no evidence of a relation between acute and late normal tissue reactions assessed in the same patients. A positive relation was found between the treatment volume and both early and late side effects. CONCLUSION After radiation treatment, a number of cells containing major changes can have a long survival and disappear very slowly, becoming a chronic focus of immunological system stimulation. This stimulation can produce, in a stochastic manner, late radiation-related adverse effects of varying severity. Further research is warranted to identify the major determinants of normal tissue radiation response to make it possible to individualize treatments and improve the outcome of radiotherapy in cancer patients.

Notch tumor suppressor function

Cancer development results from deregulated control of stem cell populations and alterations in their surrounding environment. Notch signaling is an important form of direct cell-cell communication involved in cell fate determination, stem cell potential and lineage commitment. The biological function of this pathway is critically context dependent. Here we review the pro-differentiation role and tumor suppressing function of this pathway, as revealed by loss-of-function in keratinocytes and skin, downstream of p53 and in cross-connection with other determinants of stem cell potential and/or tumor formation, such as p63 and Rho/CDC42 effectors. The possibility that Notch signaling elicits a duality of signals, involved in growth/differentiation control and cell survival will be discussed, in the context of novel approaches for cancer therapy

Modern cataract surgery for radiation-induced cataracts in retinoblastoma.

Background Surgery of radiation-induced cataracts in children with retinoblastoma (RB) is a challenge as early intervention is weighted against the need to delay surgery until complete tumour control is obtained. This study analyses the safety and functional results of such surgery. Methods In a retrospective, non-comparative, consecutive case series, we reviewed medical records of RB patients </=14 y of age who underwent either external beam radiotherapy or plaque treatment and were operated for radiation-induced cataract between 1985 and 2008. Results In total, 21 eyes of 20 RB patients were included and 18 out of the 21 eyes had Reese-Ellsworth stage V or ABC classification group D/E RB. Median interval between last treatment for RB and cataract surgery was 21.5 months, range 3-164 months. Phacoaspiration was performed in 13 eyes (61%), extra-capsular cataract extraction in 8 (39%) and intraocular lens implantation in 19 eyes (90%). The majority of cases, 11/21 (52%), underwent posterior capsulorhexis or capsulotomy and 6/21 (28%) an anterior vitrectomy. Postoperative visual acuity was >/=20/200 in 13 eyes and <20/200 in 5 eyes. Intraocular tumour recurrence was noted in three eyes. Mean postoperative follow up was 90 months+/-69 months. Conclusions Modern cataract surgery, including clear cornea approach, lens aspiration with posterior capsulotomy, anterior vitrectomy and IOL implantation is a safe procedure for radiation-induced cataract as long as RB is controlled. The visual prognosis is limited by initial tumour involvement of the macula and by corneal complications of radiotherapy. We recommend a minimal interval of 9 months between completion of treatment of retinoblastoma and cataract surgery.

Impact of genomic methylation on radiation sensitivity of colorectal carcinoma.

PURPOSE: To investigate the influence of demethylation with 5-aza-cytidine (AZA) on radiation sensitivity and to define the intrinsic radiation sensitivity of methylation deficient colorectal carcinoma cells. METHODS AND MATERIALS: Radiation sensitizing effects of AZA were investigated in four colorectal carcinoma cell lines (HCT116, SW480, L174 T, Co115), defining influence of AZA on proliferation, clonogenic survival, and cell cycling with or without ionizing radiation. The methylation status for cancer or DNA damage response-related genes silenced by promoter methylation was determined. The effect of deletion of the potential target genes (DNMT1, DNMT3b, and double mutants) on radiation sensitivity was analyzed. RESULTS: AZA showed radiation sensitizing properties at >or=1 micromol/l, a concentration that does not interfere with the cell cycle by itself, in all four tested cell lines with a sensitivity-enhancing ratio (SER) of 1.6 to 2.1 (confidence interval [CI] 0.9-3.3). AZA successfully demethylated promoters of p16 and hMLH1, genes associated with ionizing radiation response. Prolonged exposure to low-dose AZA resulted in sustained radiosensitivity if associated with persistent genomic hypomethylation after recovery from AZA. Compared with maternal HCT116 cells, DNMT3b-defcient deficient cells were more sensitive to radiation with a SER of 2.0 (CI 0.9-2.1; p = 0.03), and DNMT3b/DNMT1-/- double-deficient cells showed a SER of 1.6 (CI 0.5-2.7; p = 0.09). CONCLUSIONS: AZA-induced genomic hypomethylation results in enhanced radiation sensitivity in colorectal carcinoma. The mediators leading to sensitization remain unknown. Defining the specific factors associated with radiation sensitization after genomic demethylation may open the way to better targeting for the purpose of radiation sensitization.

Radiolabeled and native antibodies and the prospect of cure of follicular lymphoma

Advanced-stage follicular lymphoma is incurable by conventional treatment. Rituximab has been introduced in various combinations with chemotherapy and has resulted in a significantly superior treatment outcome compared with chemotherapy alone. Multiple studies have also shown the efficacy of radioimmunotherapy (RIT) both as a single agent and in combination with chemotherapy. Rituximab and RIT have clearly distinct mechanisms of action, the first acting exclusively as a biological treatment, while the second acts by a combination of biologic mechanisms and radiation effects. Despite the therapeutic efficacy of both approaches, the potential exists to further improve both modalities. Repeat administrations of RIT using appropriate radioisotopes for treatment of residual disease or new targeting strategies might afford additional benefits. Unlabeled antibody treatment could potentially benefit from the combination of antibodies directed against different target antigens or combination therapy with cytokines capable of further mobilizing patients' cellular defenses. In this review, we hypothesize that the combination of an optimized biological treatment together with radiolabeled antibodies and chemotherapy early in the disease course of advanced-stage follicular lymphoma may represent the best approach to achieve prolonged disease-free survival and eventually cure.

Effects of KRAS, BRAF, NRAS, and PIK3CA mutations on the efficacy of cetuximab plus chemotherapy in chemotherapy-refractory metastatic colorectal cancer: a retrospective consortium analysis.

Background Following the discovery that mutant KRAS is associated with resistance to anti-epidermal growth factor receptor (EGFR) antibodies, the tumours of patients with metastatic colorectal cancer are now profiled for seven KRAS mutations before receiving cetuximab or panitumumab. However, most patients with KRAS wild-type tumours still do not respond. We studied the effect of other downstream mutations on the efficacy of cetuximab in, to our knowledge, the largest cohort to date of patients with chemotherapy-refractory metastatic colorectal cancer treated with cetuximab plus chemotherapy in the pre-KRAS selection era. Methods 1022 tumour DNA samples (73 from fresh-frozen and 949 from formalin-fixed, paraffin-embedded tissue) from patients treated with cetuximab between 2001 and 2008 were gathered from 11 centres in seven European countries. 773 primary tumour samples had sufficient quality DNA and were included in mutation frequency analyses; mass spectrometry genotyping of tumour samples for KRAS, BRAF, NRAS, and PIK3CA was done centrally. We analysed objective response, progression-free survival (PFS), and overall survival in molecularly defined subgroups of the 649 chemotherapy-refractory patients treated with cetuximab plus chemotherapy. Findings 40.0% (299/747) of the tumours harboured a KRAS mutation, 14.5% (108/743) harboured a PIK3CA mutation (of which 68.5% [74/108] were located in exon 9 and 20.4% [22/108] in exon 20), 4.7% (36/761) harboured a BRAF mutation, and 2.6% (17/644) harboured an NRAS mutation. KRAS mutants did not derive benefit compared with wild types, with a response rate of 6.7% (17/253) versus 35.8% (126/352; odds ratio [OR] 0.13, 95% CI 0.07-0.22; p<0.0001), a median PFS of 12. weeks versus 24 weeks (hazard ratio [HR] 1 98, 1.66-2.36; p<0.0001), and a median overall survival of 32 weeks versus 50 weeks (1.75, 1.47-2.09; p<0.0001). In KRAS wild types, carriers of BRAF and NRAS mutations had a significantly lower response rate than did BRAF and NRAS wild types, with a response rate of 8.3% (2/24) in carriers of BRAF mutations versus 38.0% in BRAF wild types (124/326; OR 0.15, 95% CI 0.02-0.51; p=0.0012); and 7.7% (1/13) in carriers of NRAS mutations versus 38.1% in NRAS wild types (110/289; OR 0.14, 0.007-0.70; p=0.013). PIK3CA exon 9 mutations had no effect, whereas exon 20 mutations were associated with a worse outcome compared with wild types, with a response rate of 0.0% (0/9) versus 36.8% (121/329; OR 0.00,0.00-0.89; p=0.029), a median PFS of 11.5 weeks versus 24 weeks (HR 2.52, 1.33-4.78; p=0.013), and a median overall survival of 34 weeks versus 51 weeks (3.29, 1.60-6.74; p=0.0057). Multivariate analysis and conditional inference trees confirmed that, if KRAS is not mutated, assessing BRAF, NRAS, and PIK3CA exon 20 mutations (in that order) gives additional information about outcome. Objective response rates in our series were 24.4% in the unselected population, 36.3% in the KRAS wild-type selected population, and 41.2% in the KRAS, BRAF, NRAS, and PIK3CA exon 20 wild-type population. Interpretation While confirming the negative effect of KRAS mutations on outcome after cetuximab, we show that BRAF, NRAS, and PIK3CA,exon 20 mutations are significantly associated with a low response rate. Objective response rates could be improved by additional genotyping of BRAF, NRAS, and PIK3CA exon 20 mutations in a KRAS wild-type population.

Circadian and wake-dependent effects on the pupil light reflex in response to narrow-bandwidth light pulses.

PURPOSE: Nonvisual light-dependent functions in humans are conveyed mainly by intrinsically photosensitive retinal ganglion cells, which express melanopsin as photopigment. We aimed to identify the effects of circadian phase and sleepiness across 24 hours on various aspects of the pupil response to light stimulation. METHODS: We tested 10 healthy adults hourly in two 12-hour sessions covering a 24-hour period. Pupil responses to narrow bandwidth red (635 ± 18 nm) and blue (463 ± 24 nm) light (duration of 1 and 30 seconds) at equal photon fluxes were recorded, and correlated with salivary melatonin concentrations at the same circadian phases and to subjective sleepiness ratings. The magnitude of pupil constriction was determined from minimal pupil size. The post-stimulus pupil response was assessed from the pupil size at 6 seconds following light offset, the area within the redilation curve, and the exponential rate of redilation. RESULTS: Among the measured parameters, the pupil size 6 seconds after light offset correlated with melatonin concentrations (P < 0.05) and showed a significant modulation over 24 hours with maximal values after the nocturnal peak of melatonin secretion. In contrast, the post-stimulus pupil response following red light stimulation correlated with subjective sleepiness (P < 0.05) without significant changes over 24 hours. CONCLUSIONS: The post-stimulus pupil response to blue light as a marker of intrinsic melanopsin activity demonstrated a circadian modulation. In contrast, the effect of sleepiness was more apparent in the cone contribution to the pupil response. Thus, pupillary responsiveness to light is under influence of the endogenous circadian clock and subjective sleepiness.