Erratum: Cuceu, C., et al. Independent Mechanisms Lead to Genomic Instability in Hodgkin Lymphoma: Microsatellite or Chromosomal Instability. Cancers 2018, 10, 233.

The authors wish to make the following corrections to this paper [...].

Atypical Presentation of Acute Disseminated Encephalomyelitis (ADEM) in a Middle-Aged Adult.

BACKGROUND Acute disseminated encephalomyelitis (ADEM) is a demyelinating disease that usually presents in pediatric patients, usually following a viral or bacterial infection. The clinical findings in ADEM include acute neurologic decline that typically presents with encephalopathy, with some cases progressing to multiple sclerosis. An atypical case of ADEM is reported that presented in a middle-aged adult. CASE REPORT A 46-year-old Caucasian man, who had recently emigrated to the US from Ukraine, presented with gait abnormalities that began four days after he developed abdominal cramps. Magnetic resonance imaging (MRI) of the brain with contrast, fluid-attenuated inversion recovery (FLAIR), and T2-weighting showed contrast-enhancing, patchy, diffuse lesions in both cerebral hemispheres. Cerebrospinal fluid (CSF) was negative for oligoclonal bands. On hospital admission, the patient was treated with intravenous (IV) methylprednisolone, 500 mg twice daily. He responded well and was discharged from hospital after a week, with resolution of his presenting symptoms and signs. CONCLUSIONS This report is of an atypical presentation of ADEM in a middle-aged patient who presented with spastic paresis. Although there are no set guidelines for the diagnosis of ADEM in adults, this diagnosis should be considered in patients with acute onset of demyelinating lesions in cerebral MRI. As this case has shown, first-line treatment is with high-dose steroids, which can be rapidly effective.

Ontogeny and programming of the fetal temporal cortical endocannabinoid system by moderate maternal nutrient reduction in baboons (Papio spp.).

Poor nutrition during pregnancy is a worldwide public health problem. Maternal nutrient reduction (MNR) is associated with maternal and fetal stress and a sex-dependent decrease in nonhuman primate (NHP) cognitive performance. Early life stress potentiates epileptogenesis in a sex-specific manner, and temporal lobe (TL) epilepsy is associated with neurocognitive disorders. The endogenous cannabinoid system (ECS) demonstrates remarkable developmental changes and plays a key role in aging-related diseases (e.g., dementia). Baboons have been studied as a natural model of epilepsy and express all ECS system components. We therefore evaluated baboon fetal temporal cortex ECS ontogenic and MNR-dependent changes. At 120 days gestational age (dGA) (term 185 days), maternal, fetal, and placental morphometry were similar between control and MNR pregnancies. MNR maternal weight gain was decreased compared with controls at 165 dGA independent of fetal sex. In male fetuses, expression of ECS synthesizing and degrading enzymes was gestational age-dependent, with the exception of fatty acid amide hydrolase (FAAH). MNR had a sex-specific effect on the protein expression of CB1R during development: CB1R protein expression was decreased in fetal temporal cortex of male fetuses at 120 and 140 dGA. Our data reveal that the MNR has sex-specific effects on temporal cortical expression of the ECS in baboon offspring and shows vulnerability of ECS in male fetuses during gestation.

Independent Mechanisms Lead to Genomic Instability in Hodgkin Lymphoma: Microsatellite or Chromosomal Instability †.

Background: Microsatellite and chromosomal instability have been investigated in Hodgkin lymphoma (HL). Materials and Methods: We studied seven HL cell lines (five Nodular Sclerosis (NS) and two Mixed Cellularity (MC)) and patient peripheral blood lymphocytes (100 NS-HL and 23 MC-HL). Microsatellite instability (MSI) was assessed by PCR. Chromosomal instability and telomere dysfunction were investigated by FISH. DNA repair mechanisms were studied by transcriptomic and molecular approaches. Results: In the cell lines, we observed high MSI in L428 (4/5), KMH2, and HDLM2 (3/5), low MSI in L540, L591, and SUP-HD1, and none in L1236. NS-HL cell lines showed telomere shortening, associated with alterations of nuclear shape. Small cells were characterized by telomere loss and deletion, leading to chromosomal fusion, large nucleoplasmic bridges, and breakage/fusion/bridge (B/F/B) cycles, leading to chromosomal instability. The MC-HL cell lines showed substantial heterogeneity of telomere length. Intrachromosmal double strand breaks induced dicentric chromosome formation, high levels of micronucleus formation, and small nucleoplasmic bridges. B/F/B cycles induced complex chromosomal rearrangements. We observed a similar pattern in circulating lymphocytes of NS-HL and MC-HL patients. Transcriptome analysis confirmed the differences in the DNA repair pathways between the NS and MC cell lines. In addition, the NS-HL cell lines were radiosensitive and the MC-cell lines resistant to apoptosis after radiation exposure. Conclusions: In mononuclear NS-HL cells, loss of telomere integrity may present the first step in the ongoing process of chromosomal instability. Here, we identified, MSI as an additional mechanism for genomic instability in HL.

The Transition between Telomerase and ALT Mechanisms in Hodgkin Lymphoma and Its Predictive Value in Clinical Outcomes.

Background: We analyzed telomere maintenance mechanisms (TMMs) in lymph node samples from HL patients treated with standard therapy. The TMMs correlated with clinical outcomes of patients. Materials and Methods: Lymph node biopsies obtained from 38 HL patients and 24 patients with lymphadenitis were included in this study. Seven HL cell lines were used as in vitro models. Telomerase activity (TA) was assessed by TRAP assay and verified through hTERT immunofluorescence expression; alternative telomere lengthening (ALT) was also assessed, along with EBV status. Results: Both TA and ALT mechanisms were present in HL lymph nodes. Our findings were reproduced in HL cell lines. The highest levels of TA were expressed in CD30-/CD15- cells. Small cells were identified with ALT and TA. Hodgkin and Reed Sternberg cells contained high levels of PML bodies, but had very low hTERT expression. There was a significant correlation between overall survival (p < 10-3), event-free survival (p < 10-4), and freedom from progression (p < 10-3) and the presence of an ALT profile in lymph nodes of EBV+ patients. Conclusion: The presence of both types of TMMs in HL lymph nodes and in HL cell lines has not previously been reported. TMMs correlate with the treatment outcome of EBV+ HL patients.

The Translationally Controlled Tumor Protein and the Cellular Response to Ionizing Radiation-Induced DNA Damage.

The absorption of ionizing radiation by living cells can directly disrupt atomic structures, producing chemical and biological changes. It can also act indirectly through radiolysis of water, thereby generating reactive chemical species that may damage nucleic acids, proteins, and lipids. Together, the direct and indirect effects of radiation initiate a series of biochemical and molecular signaling events that may repair the damage or culminate in permanent physiological changes or cell death. In efforts to gain insight into the mechanisms underlying these effects, we observed a prominent upregulation of the Translationally Controlled Tumor Protein (TCTP) in low dose/low dose rate 137Cs γ-irradiated cells that was associated with adaptive responses that reduced chromosomal damage to a level lower than what occurs spontaneously. Therefore, TCTP may support the survival and genomic integrity of irradiated cells through a role in the DNA damage response. Consistent with this postulate, TCTP was shown to physically interact with ATM, an early sensor of DNA damage, and to exist in a complex with γH2A.X, in agreement with its distinct localization with the foci of the DNA damage marker proteins γH2A.X, 53BP1, and P-ATM. Cells lacking TCTP failed to repair chromosomal damage induced by γ-rays. Further, TCTP was shown to interact with the DNA-binding subunits, Ku70 and Ku80, of DNA-PK, a major participant in nonhomologous end joining of DNA double strand breaks. Moreover, TCTP physically interacted with p53, and its knockdown attenuated the radiation-induced G1 delay, but prolonged the G2 delay. Here, we briefly review the biochemical events leading to DNA damage by ionizing radiation and to its sensing and repair, and highlight TCTP's critical role in maintaining genomic integrity in response to DNA-damaging agents.

Comparison of Individual Radiosensitivity to γ-Rays and Carbon Ions.

Carbon ions are an up-and-coming ion species, currently being used in charged particle radiotherapy. As it is well established that there are considerable interindividual differences in radiosensitivity in the general population that can significantly influence clinical outcomes of radiotherapy, we evaluate the degree of these differences in the context of carbon ion therapy compared with conventional radiotherapy. In this study, we evaluate individual radiosensitivity following exposure to carbon-13 ions or γ-rays in peripheral blood lymphocytes of healthy individuals based on the frequency of ionizing radiation (IR)-induced DNA double strand breaks (DSBs) that was either misrepaired or left unrepaired to form chromosomal aberrations (CAs) (simply referred to here as DSBs for brevity). Levels of DSBs were estimated from the scoring of CAs visualized with telomere/centromere-fluorescence in situ hybridization (TC-FISH). We examine radiosensitivity at the dose of 2 Gy, a routinely administered dose during fractionated radiotherapy, and we determined that a wide range of DSBs were induced by the given dose among healthy individuals, with highly radiosensitive individuals harboring more IR-induced breaks in the genome than radioresistant individuals following exposure to the same dose. Furthermore, we determined the relative effectiveness of carbon irradiation in comparison to γ-irradiation in the induction of DSBs at each studied dose (isodose effect), a quality we term "relative dose effect" (RDE). This ratio is advantageous, as it allows for simple comparison of dose-response curves. At 2 Gy, carbon irradiation was three times more effective in inducing DSBs compared with γ-irradiation (RDE of 3); these results were confirmed using a second cytogenetic technique, multicolor-FISH. We also analyze radiosensitivity at other doses (0.2-15 Gy), to represent hypo- and hyperfractionation doses and determined that RDE is dose dependent: high ratios at low doses, and approaching 1 at high doses. These results could have clinical implications as IR-induced DNA damage and the ensuing CAs and genomic instability can have significant cellular consequences that could potentially have profound implications for long-term human health after IR exposure, such as the emergence of secondary cancers and other pathobiological conditions after radiotherapy.

Global quantification of γH2AX as a triage tool for the rapid estimation of received dose in the event of accidental radiation exposure.

The phosphorylation of the H2AX histone to form γH2AX foci has been shown to be an accurate biomarker of ionizing radiation exposure. It is well established that there is a one-to-one correlation between the number of γH2AX foci and radiation-induced double strand breaks in cellular DNA, which can be translated to the received dose. However, manual counting of foci is time-consuming, and cannot accommodate high throughput analysis required to obtain rapid results for medical triage purposes in the case of large-scale accidental exposure. Furthermore, the accuracy of γH2AX measurements could potentially be compromised by delays between the time of exposure and analysis of results, as well as inter-cellular and inter-individual variability of this biological response. To evaluate more rapid approaches of quantifying γH2AX for use in an emergency situation, and to determine the impact of inter-individual variability, we compared two methods of global γH2AX fluorescence quantification (low magnification immunofluorescence microscopy and flow cytometry) to the well-established γH2AX foci scoring method in human primary fibroblasts. All three approaches were well correlated, indicating that global γH2AX fluorescence measurements are suitable for dose estimation. For rapid triage in an emergency situation, we propose the use of flow cytometry, as it is more highly correlated with foci scoring and because of the speed and ease of the method. Dose response curves (0.25-6Gy) using flow cytometry measurements showed that inter-individual variability in global γH2AX fluorescence is statistically insignificant at 4h post-irradiation. Based on these data, we propose calibration curves that can be applied to populations exposed to moderate radiation doses to estimate individual received doses, independent of individual radiosensitivity, at this specific time point post-irradiation using human fibroblasts and lymphocytes. Furthermore, we define three triage categories that could facilitate immediate and follow-up care in the case of a radiological accident.

Crosstalk between telomere maintenance and radiation effects: A key player in the process of radiation-induced carcinogenesis.

It is well established that ionizing radiation induces chromosomal damage, both following direct radiation exposure and via non-targeted (bystander) effects, activating DNA damage repair pathways, of which the proteins are closely linked to telomeric proteins and telomere maintenance. Long-term propagation of this radiation-induced chromosomal damage during cell proliferation results in chromosomal instability. Many studies have shown the link between radiation exposure and radiation-induced changes in oxidative stress and DNA damage repair in both targeted and non-targeted cells. However, the effect of these factors on telomeres, long established as guardians of the genome, still remains to be clarified. In this review, we will focus on what is known about how telomeres are affected by exposure to low- and high-LET ionizing radiation and during proliferation, and will discuss how telomeres may be a key player in the process of radiation-induced carcinogenesis.

Lead Exposure Induces Telomere Instability in Human Cells.

Lead (Pb) is an important environmental contaminant due to its widespread use over many centuries. While it affects primarily every organ system of the body, the most pernicious effects of Pb are on the central nervous system leading to cognitive and behavioral modification. Despite decades of research, the mechanisms responsible for Pb toxicity remain poorly understood. Recent work has suggested that Pb exposure may have consequences on chromosomal integrity as it was shown that Pb exposure leads to the generation of γH2Ax foci, a well-established biomarker for DNA double stranded break (DSB formation). As the chromosomal localization of γH2Ax foci plays an important role in determining the molecular mechanism responsible for their formation, we examined the localization of Pb-induced foci with respect to telomeres. Indeed, short or dysfunctional telomeres (uncapped or damaged telomeres) may be recognized as DSB by the DNA repair machinery, leading to "telomere-Induced Foci" (TIFs). In the current study, we show that while Pb exposure did not increase intra-chromosomal foci, it significantly induced TIFs, leading in some cases, to chromosomal abnormalities including telomere loss. The evidence suggests that these chromosomal abnormalities are likely due to perturbation of telomere replication, in particular on the lagging DNA strand. We propose a mechanism by which Pb exposure leads to the loss of telomere maintenance. As numerous studies have demonstrated a role for telomere maintenance in brain development and tissue homeostasis, our results suggest a possible mechanism for lead-induced neurotoxicity.