Increased Parietal and Frontal Activation after Remission from Recurrent Major Depression: A Repeated fMRI Study

Nine patients with unipolar major depression were scanned with MRI twice over a 2-year period, and compared with 12 healthy control subjects. All patients fulfilled criteria for major depressive disorder, recurrent type, at first scanning. Level of depressive psychopathology was assessed by the Hamilton Depression Rating Scale. The participants had to work on a mental arithmetics/working memory task while in the MR scanner. The task consisted of single digits (1 to 9) that were shown to the participant, who had to add the numbers in successive pairs and press a response button when the sum was 10. Neuronal activation was recorded based on the BOLD contrast phenomenon in a functional MRI protocol. The results showed significant increase in activation for the patients in the inferior frontal gyrus and the superior and inferior parietal lobule at the second compared with the first MR scanning session. There were also significant correlations between the HDRS scores and neuronal activation which showed a negative correlation particularly in the inferior frontal and parietal lobe areas, which overlapped with similar areas activated in the healthy control participants. This may indicate normalization of brain activation in depressed patients as a function of time from an illness phase to a remission/recovery state.

Targeting the LRP5 Pathway Improves Bone Properties in a Mouse Model of Osteogenesis Imperfecta

The cell surface receptor low‐density lipoprotein receptor‐related protein 5 (LRP5) is a key regulator of bone mass and bone strength. Heterozygous missense mutations in LRP5 cause autosomal dominant high bone mass (HBM) in humans by reducing binding to LRP5 by endogenous inhibitors, such as sclerostin (SOST). Mice heterozygous for a knockin allele (Lrp5^p.A214V) that is orthologous to a human HBM‐causing mutation have increased bone mass and strength. Osteogenesis imperfecta (OI) is a skeletal fragility disorder predominantly caused by mutations that affect type I collagen. We tested whether the LRP5 pathway can be used to improve bone properties in animal models of OI. First, we mated Lrp5^+/p.A214V mice to Col1a2^+/p.G610C mice, which model human type IV OI. We found that Col1a2^+/p.G610C;Lrp5^+/p.A214V offspring had significantly increased bone mass and strength compared to Col1a2^+/p.G610C;Lrp5^+/+ littermates. The improved bone properties were not a result of altered mRNA expression of type I collagen or its chaperones, nor were they due to changes in mutant type I collagen secretion. Second, we treated Col1a2^+/p.G610C mice with a monoclonal antibody that inhibits sclerostin activity (Scl‐Ab). We found that antibody‐treated mice had significantly increased bone mass and strength compared to vehicle‐treated littermates. These findings indicate increasing bone formation, even without altering bone collagen composition, may benefit patients with OI. © 2014 American Society for Bone and Mineral Research.     

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.     

The European Prevalence of Resistance Associated Substitutions among Direct Acting Antiviral Failures

Background: Approximately 71 million people are still in need of direct-acting antiviral agents (DAAs). To achieve the World Health Organization Hepatitis C elimination goals, insight into the prevalence and influence of resistance associated substitutions (RAS) is of importance. Collaboration is key since DAA failure is rare and real-life data are scattered. We have established a European collaboration, HepCare, to perform in-depth analysis regarding RAS prevalence, patterns, and multiclass occurrence. Methods: Data were extracted from the HepCare cohort of patients who previously failed DAA therapy. Geno—and subtypes were provided by submitters and mostly based on in-house assays. They were reassessed using the Comet HCV subtyping tool. We considered RAS to be relevant if they were associated with DAA failure in vivo previously reported in literature. Results: We analyzed 938 patients who failed DAA therapy from ten different European countries. There were 239 genotypes (GT) 1a, 380 GT1b, 19 GT2c, 205 GT3a, 14 GT4a, and 68 GT4d infections. Several unusual subtypes (n = 15) (GT1b/g/l, GT3b, GT4k/n/r/t) were present. RAS appeared in over 80% of failures and over a quarter had three or more RAS. Multiclass RAS varied over target region and genotype between 0–48%. RAS patterns such as the Q30R + L31M and Q30R + Y93H in GT1a, the L31V + Y93H and L31V + Y93H for GT1b, and A30K + L31M and A30K/V + Y93H for GT3a all occurred with a prevalence below 5%. Conclusion: RAS occur frequently after DAA failures and follow a specific genotype and drug related pattern. Interpretation of the influence of RAS on retreatment is challenging due to various patterns, patients’ characteristics, and previous treatment history. Moving towards HCV elimination, an ongoing resistance surveillance is essential to track the presence of RAS, RAS patterns and gather data for a re-treatment algorithm.     

A 7-Tesla MRI study of the periaqueductal gray: resting state and task activation under threat

The periaqueductal gray (PAG) is a region of the midbrain implicated in a variety of behaviors including defensive responses to threat. Despite the wealth of knowledge pertaining to the differential functional roles of the PAG columns in nonhuman and human research, the basic functional connectivity of the PAG at rest has not been well characterized. Therefore, the current study utilized 7-Tesla magnetic resonance imaging (MRI) to characterize PAG functional connectivity at rest and task activation under uncertain threat. A sample of 53 neurologically healthy undergraduate participants (M_age = 22.2, s.d._age = 3.62) underwent structural and resting state functional MRI scans. Supporting previous work, voxel-wise analyses showed that the PAG is functionally connected to emotion regulation and fear networks. The comparison of functional connectivity of PAG columns did not reveal any significant differences. Thirty-five participants from the same sample also completed an uncertain threat task with blocks of three conditions—no shock, predictable shock and unpredictable shock. There were no robust activity differences within the PAG columns or the whole PAG across conditions although there was differential activity at the voxel level in the PAG and in other regions theoretically relevant to uncertain threat. Results of this study elucidate PAG connectivity at rest and activation in response to uncertain threat.