A novel function for CDK2 activity at meiotic crossover sites.

Genetic diversity in offspring is induced by meiotic recombination, which is initiated between homologs at >200 sites originating from meiotic double-strand breaks (DSBs). Of this initial pool, only 1-2 DSBs per homolog pair will be designated to form meiotic crossovers (COs), where reciprocal genetic exchange occurs between parental chromosomes. Cyclin-dependent kinase 2 (CDK2) is known to localize to so-called "late recombination nodules" (LRNs) marking incipient CO sites. However, the role of CDK2 kinase activity in the process of CO formation remains uncertain. Here, we describe the phenotype of 2 Cdk2 point mutants with elevated or decreased activity, respectively. Elevated CDK2 activity was associated with increased numbers of LRN-associated proteins, including CDK2 itself and the MutL homolog 1 (MLH1) component of the MutLγ complex, but did not lead to increased numbers of COs. In contrast, reduced CDK2 activity leads to the complete absence of CO formation during meiotic prophase I. Our data suggest an important role for CDK2 in regulating MLH1 focus numbers and that the activity of this kinase is a key regulatory factor in the formation of meiotic COs.

Knockout of the non-essential gene SUGCT creates diet-linked, age-related microbiome disbalance with a diabetes-like metabolic syndrome phenotype.

SUGCT (C7orf10) is a mitochondrial enzyme that synthesizes glutaryl-CoA from glutarate in tryptophan and lysine catabolism, but it has not been studied in vivo. Although mutations in Sugct lead to Glutaric Aciduria Type 3 disease in humans, patients remain largely asymptomatic despite high levels of glutarate in the urine. To study the disease mechanism, we generated SugctKO mice and uncovered imbalanced lipid and acylcarnitine metabolism in kidney in addition to changes in the gut microbiome. After SugctKO mice were treated with antibiotics, metabolites were comparable to WT, indicating that the microbiome affects metabolism in SugctKO mice. SUGCT loss of function contributes to gut microbiota dysbiosis, leading to age-dependent pathological changes in kidney, liver, and adipose tissue. This is associated with an obesity-related phenotype that is accompanied by lipid accumulation in kidney and liver, as well as "crown-like" structures in adipocytes. Furthermore, we show that the SugctKO kidney pathology is accelerated and exacerbated by a high-lysine diet. Our study highlights the importance of non-essential genes with no readily detectable early phenotype, but with substantial contributions to the development of age-related pathologies, which result from an interplay between genetic background, microbiome, and diet in the health of mammals.

Intraobserver and interobserver variability of the bone marrow burden (BMB) score for the assessment of disease severity in Gaucher disease. Possible impact of reporting experience.

AIM: To evaluate the intraobserver and interobserver agreement for bone marrow burden (BMB) scores for individual examinations and for the change in BMB score over time in the same patient. METHODS: A total of 119 sets of MR images of the lumbar spine and femora from 60 patients with Gaucher disease were included. Each set of MR images was scored using the BMB score independently by two experienced MSK radiologists. One radiologist performed a second read four weeks later. Intraobserver and interobserver agreement was assessed using Bland-Altman analysis and weighted kappa scores. RESULTS: BMB scores (n=119) demonstrated fair intraobserver agreement (weighted kappa=0.53) with a mean difference of -0.20 and 95% limits of agreement (LOA) of (-3.41, 3.01). Inter observer agreement was poor with weighted kappa 0.28 with mean difference of -0.16 and 95% LOA of (-4.45, 4.11). Change in BMB scores over time (n=59) demonstrated poor/fair intraobserver agreement (weighted kappa 0.41, mean difference-0.20 and 95% LOA (-4.35, 3.94)). Interobserver agreement was poor (weighted kappa 0.25, mean difference -0.12 with wide 95% LOA (-6.23, 5.99)). CONCLUSION: Significant interobserver, and to a lesser extent intraobserver, variation occurs with blinded BMB scoring of Gaucher disease.

The role of early magnetic resonance imaging in predicting survival on bevacizumab for recurrent glioblastoma: Results from a prospective clinical trial (CABARET).

BACKGROUND: Bevacizumab has been associated with prolonged progression-free survival for patients with recurrent glioblastoma; however, not all derive a benefit. An early indicator of efficacy or futility may allow early discontinuation for nonresponders. This study prospectively assessed the role of early magnetic resonance imaging (eMRI) and its correlation with subsequent routine magnetic resonance imaging (MRI) results and survival. METHODS: Patients were part of a randomized phase 2 clinical trial (CABARET) comparing bevacizumab with bevacizumab plus carboplatin for recurrent glioblastoma. eMRI was conducted after 4 weeks in the trial (after 2 treatments with bevacizumab [10 mg/kg every 2 weeks]). The results were compared with the results of the subsequent 8-week MRI standard. RESULTS: For 119 of 122 patients, eMRI was available, and 111 had subsequent MRI for comparison. Thirty-six (30%) had an early radiological response, and 17 (14%) had progressive disease. The concordance between eMRI and 8-week MRI was moderate (κ = 0.56), with most providing the same result (n = 79 [71%]). There was strong evidence that progression-free survival and overall survival were predicted by the eMRI response (both P values < .001). The median survival was 8.6 months for an eMRI response, 6.6 months for stable disease, and 3.7 months for progressive disease; the hazard ratio (progressive disease vs stable disease) was 3.4 (95% confidence interval, 1.9-6.0). Landmark analyses showed that eMRI progression was a strong predictor of mortality independent of other potential baseline predictors. CONCLUSIONS: In this study, early progression on MRI appears to be a robust marker of a poor prognosis for patients on bevacizumab. Cancer 2017;123:3576-82. © 2017 American Cancer Society.

MRI in transverse myelitis.

Transverse myelitis is an acute inflammatory disease of the spinal cord, characterized by rapid onset of bilateral neurological symptoms. Weakness, sensory disturbance, and autonomic dysfunction evolve over hours or days, most progressing to maximal clinical severity within 10 days of onset. At maximal clinical severity, half will have a paraparesis, and almost all patients have sensory disturbance and bladder dysfunction. Residual disability is divided equally between severe, moderate and minimal or none. The causes of transverse myelitis are diverse; etiologies implicated include demyelinating conditions, collagen vascular disease, and parainfectious causes, however, despite extensive diagnostic work-up many cases are considered idiopathic. Due to heterogeneity in pathogenesis, and the similarity of its clinical presentation with those of various noninflammatory myelopathies, transverse myelitis has frequently been viewed as a diagnostic dilemma. However, as targeted therapies to optimize patient outcome develop, timely identification of the underlying etiology is becoming increasingly important. In this review, we describe the imaging and clinical features of idiopathic and disease-associated transverse myelitis and its major differentials, with discussion of how MR imaging features assist in the identification of various sub-types of transverse myelitis. We will also discuss the potential for advanced MR techniques to contribute to diagnosis and prognostication.

Identification PMS1 and PMS2 as potential meiotic substrates of CDK2 activity.

Cyclin dependent-kinase 2 (CDK2) plays important functions during the mitotic cell cycle and also facilitates several key events during germ cell development. The majority of CDK2's known meiotic functions occur during prophase of the first meiotic division. Here, CDK2 is involved in the regulation of meiotic transcription, the pairing of homologous chromosomes, and the maturation of meiotic crossover sites. Despite that some of the CDK2 substrates are known, few of them display functions in meiosis. Here, we investigate potential meiotic CDK2 substrates using in silico and in vitro approaches. We find that CDK2 phosphorylates PMS2 at Thr337, PMS1 at Thr331, and MLH1 in vitro. Phosphorylation of PMS2 affects its interaction with MLH1 to some degree. In testis extracts from mice lacking Cdk2, there are changes in expression of PMS2, MSH2, and HEI10, which may be reflective of the loss of CDK2 phosphorylation. Our work has uncovered a few CDK2 substrates with meiotic functions, which will have to be verified in vivo. A better understanding of the CDK2 substrates will help us to gain deeper insight into the functions of this universal kinase.

ZO-2/Tjp2 suppresses Yap and Wwtr1/Taz-mediated hepatocyte to cholangiocyte transdifferentiation in the mouse liver.

TJP2/ZO-2-inactivating mutations in humans cause progressive cholestatic liver disease. Liver-specific deletion of Tjp2 in the mouse (Tjp2 cKO mice) leads to mild progressive cholestasis without an overt degradation of the bile-blood barrier (BBB). These mice are more susceptible to cholic acid (CA) induced liver injury. Interestingly, while initially also more susceptible, Tjp2 cKO mice develop tolerance to a DDC-supplemented diet. The DDC diet induces an exacerbated ductular reaction in Tjp2 cKO mice, which arises from the transdifferentiation of hepatocytes to cholangiocytes. Consequently, this transdifferentiation is only observed if Tjp2 is inactivated in hepatocytes, but not if deleted in cholangiocytes. The DDC-diet-induced hepatocyte transdifferentiation in Tjp2 cKO mice requires Yap and Wwtr1/Taz, whose protein expression is upregulated in hepatocytes lacking Tjp2, but is independent of Notch2. Although inactivating Tjp2 is sufficient for the upregulation of Yap and Wwtr1/Taz protein, efficient transdifferentiation requires the DDC-diet insult. Thus, Tjp2 negatively regulates Yap/Taz-mediated transdifferentiation of hepatocytes to cholangiocytes in response to DDC-diet-induced liver injury. Furthermore, transdifferentiation is regulated at multiple levels and the type of injury inflicted on the Tjp2 deficient liver plays an important role in the resulting pathophysiology.

Case Report: Neurocysticercosis Acquired in Australia.

Neurocysticercosis (NCC) is a disease caused by infection of the central nervous system with the larval stage of the tapeworm Taenia solium. This disease is endemic in many parts of the world, including Africa, Asia, and Latin America, where animal husbandry practices are common such that pigs reared for human consumption ingest feces from humans infected with T. solium. Neurocysticercosis is rarely acquired in economically affluent regions, including North America, Central Europe, Japan, and Australasia, and in countries where pork consumption is discouraged by religious or social practices. In these countries, NCC is usually diagnosed in immigrants or returning travelers who have spent time in endemic regions. Here, we report a case of NCC in a 25-year-old woman presenting with worsening visual symptoms in association with headache, diagnosed previously as a migraine with visual aura. This person had always lived in Australia and had never traveled overseas to a country endemic for T. solium. The unusual features of the clinical presentation and epidemiology are highlighted to raise physicians' awareness that attention needs to be paid to the risk of autochthonous infection occurring in non-endemic countries.

Comparison between site and central radiological assessments for patients with recurrent glioblastoma on a clinical trial.

AIM: Assessment of magnetic resonance imaging (MRI) in glioblastoma can be challenging. For patients with recurrent glioblastoma managed on the CABARET trial, we compared disease status assessed at hospitals and subsequent blinded central expert radiological review. METHODS: MRI results and clinical status at specified time points were used for site and central assessment of disease status. Clinical status was determined by the site. Response Assessment in Neuro-Oncology (RANO) criteria were used for both assessments. Site and central assessments of progression-free survival (PFS) and response rates were compared. Inter-rater variability for central review progression dates was assessed. RESULTS: Central review resulted in shorter PFS in 45% of 89 evaluable patients (n = 40). Median PFS was 3.6 (central) versus 3.9 months (site) (hazard ratio 1.5, 95% confidence interval 1.3-1.8, P < 0.001). Responses were documented more frequently by sites (n = 16, 18%) than centrally (n = 11, 12%). Seven of 120 patients continued on trial without site-determined progression for more than 6 months beyond the central review determination of progression. Of scans reviewed by all three central reviewers, 33% were fully concordant for progression date. CONCLUSION: While the difference between site and central PFS dates was statistically significant, the 0.3-month median difference is small. The variability within central review is consistent with previous studies, highlighting the challenges in MRI interpretation in this context. A small proportion of patients benefited from treatment well beyond the centrally determined progression date, reinforcing that clinical status together with radiology results are important determinants of whether a therapy is effective for an individual.

Use of a suite of biomarkers to assess the effects of carbamazepine, bisphenol A, atrazine, and their mixtures on green mussels, Perna viridis.

The present study investigated the toxicity of several emerging contaminants: the pharmaceutical drug carbamazepine (CBZ), the plasticizer bisphenol A (BPA), and the herbicide atrazine (ATZ) in a marine bivalve. Green mussels (Perna viridis) were exposed to different concentrations of CBZ, BPA, and ATZ, either individually or as mixtures over a 7-d period, and a suite of molecular and cellular biomarkers were analyzed: biomarkers of immunotoxicity (total hemocyte count, phagocytosis, extracellular lysozyme), genotoxicity (Comet assay), neurotoxicity (inhibition of acetylcholinesterase [AChE]), endocrine disruption (vitellin-like proteins), and detoxification enzymes (cytochrome P4501A [CYP1A], 7-ethoxyresorufin O-deethylase [EROD], and glutathione-S-transferase [GST]). Results of the single-chemical exposure tests highlighted the relatively low toxicity of CBZ because most biomarker responses observed were recorded at concentrations well above environmental levels. Bisphenol A exposure at environmentally realistic concentrations resulted in clear immunomodulatory, genotoxic, and endocrine-disruptive effects. Similarly, 3 of the 10 biomarkers tested on green mussels (genotoxicity, inhibition of AchE, and EROD) responded after exposure to ATZ at environmentally relevant doses or below, and confirmed the potency of this herbicide to marine bivalves. Exposure tests using mixtures of CBZ, BPA, and ATZ also revealed that these 3 substances were generally acting in an additive manner on the selected biomarkers, at environmental doses, with some exceptions (antagonism and/or synergy) at low and high concentrations. The present study also confirms that most of the biomarkers used are suitable for biomonitoring studies with green mussels. Environ Toxicol Chem 2017;36:429-441. © 2016 SETAC.

Continuing or ceasing bevacizumab beyond progression in recurrent glioblastoma: an exploratory randomized phase II trial.

BACKGROUND: In patients with recurrent glioblastoma, the benefit of bevacizumab beyond progression remains uncertain. We prospectively evaluated continuing or ceasing bevacizumab in patients who progressed while on bevacizumab. METHODS: CABARET, a phase II study, initially randomized patients to bevacizumab with or without carboplatin (Part 1). At progression, eligible patients underwent a second randomization to continue or cease bevacizumab (Part 2). They could also receive additional chemotherapy regimens (carboplatin, temozolomide, or etoposide) or supportive care. RESULTS: Of 120 patients treated in Part 1, 48 (80% of the anticipated 60-patient sample size) continued to Part 2. Despite randomization, there were some imbalances in patient characteristics. The best response was stable disease in 7 (30%) patients who continued bevacizumab and 2 (8%) patients who stopped receiving bevacizumab. There were no radiological responses. Median progression-free survival was 1.8 vs 2.0 months (bevacizumab vs no bevacizumab; hazard ratio [HR], 1.08; 95% CI, .59-1.96; P = .81). Median overall survival was 3.4 vs 3.0 months (HR, .84; 95% CI, .47-1.50; P = .56 and HR .70; 95% CI .38-1.29; P = .25 after adjustment for baseline factors). Quality-of-life scores did not significantly differ between arms. While the maximum daily steroid dose was lower in the continuation arm, the difference was not statistically significant. CONCLUSIONS: Patients who continued bevacizumab beyond disease progression did not have clear survival improvements, although the study was not powered to detect other than very large differences. While these data provide the only randomized evidence related to continuing bevacizumab beyond progression in recurrent glioblastoma, the small sample size precludes definitive conclusions and suggests this remains an open question.

Association of aspirin resistance with increased stroke severity and infarct size.

OBJECTIVE: To investigate the relationship between aspirin resistance and clinical and neuroimaging measures of stroke severity in acute stroke patients. DESIGN: Prospective single-center survey of acute ischemic stroke patients receiving aspirin therapy. SETTING: The Royal Melbourne Hospital, Parkville, Victoria, Australia. PATIENTS: Ninety acute stroke patients who previously received aspirin therapy were enrolled. MAIN OUTCOME MEASURES: Clinical stroke severity was measured using the National Institutes of Health Stroke Scale (NIHSS) and stroke infarct size was measured using the Alberta Stroke Program Early CT Score (ASPECTS). Aspirin resistance was measured using the VerifyNow system. RESULTS: The mean (SD) age was 75 (9.9) years and 64.4% were male. The median NIHSS score and ASPECTS were 4 (interquartile range [IQR], 3-10) and 9 (IQR, 6-10), respectively. Aspirin resistance was detected in 28.9% (95% CI, 0.19 to 0.38) of all patients. The median aspirin reaction unit (ARU) was 486.0 (IQR, 432.3-557.0). Every 1-point increase in ARU was associated with a 0.03-point increase in NIHSS score (95% CI, 0.01 to 0.04; P<.001) and a 0.02-point decrease in ASPECTS (95% CI, -0.03 to -0.01; P<.001). This corresponded to an approximate median increase of 1 point in NIHSS score for every 33-point increase in ARU or a decrease of 1 point in ASPECTS for every 50-point increase in ARU. CONCLUSIONS: Aspirin resistance is associated with increased clinical severity and stroke infarct volume in acute stroke patients. Our results support the need for a randomized controlled study to investigate alternative antiplatelet therapy in patients with aspirin resistance.

Neuroimaging in acute transverse myelitis.

Transverse myelitis is an acute inflammatory condition. A relatively rare condition, the diversity of causes makes it an important diagnostic challenge. An approach to the classification and work-up standardizes diagnostic criteria and terminology to facilitate clinical research, and forms a useful tool in the clinical work-up for patients at presentation. Its pathogenesis can be grouped into four categories. Imaging appearances can be nonspecific; however, the morphology of cord involvement, enhancement pattern, and presence of coexistent abnormalities on MR imaging can provide clues as to the causes. Neuroimaging is important in identifying subgroups that may benefit from specific treatment.