Preliminary validation of varicella zoster virus thymidine kinase as a novel reporter gene for PET

IntroductionImaging of gene expression with positron emission tomography (PET) has emerged as a powerful tool for biomedical research during the last decade. The prototypical herpes simplex virus type 1 thymidine kinase (HSV1-TK) PET reporter gene (PRG) is widely used and many other PRGs have also been validated. We investigated varicella zoster virus thymidine kinase (VZV-tk) as new PRG with radiolabeled bicyclic nucleoside analogues (BCNAs) as PET tracers.MethodsThe uptake and washout of four different radiolabeled BCNAs was evaluated in cells expressing VZV-tk after lentiviral vector (LV) transduction and in control cells. Metabolism of the tracers was assayed by high pressure liquid chromatography (HPLC). Mice bearing VZV-TK expressing xenografts were imaged with PET.ResultsHigh uptake in VZV-tk expressing cells was seen for 3 of the 4 tracers tested. The uptake of the tracers could be blocked by the presence of excess thymidine in the incubation solution. Cellular retention was variable, with one tracer showing an acceptable half-life of ~ 1 hour. The amount of intracellular tracer correlated with the titer of LV used to transduce the cells. VZV-TK dependent conversion into metabolites was shown by HPLC. No specific accumulation was observed in cells expressing a fusion protein containing an HSV1-TK moiety. VZV-tk expression in xenografts resulted in a 60% increase in uptake in vivo as measured with PET.ConclusionsWe have validated the combination of VZV-tk and radiolabeled BCNAs as new PRG/PRP system. Further optimization of the PRPs and the PRG are warranted to increase the signal.     

Diagnostic accuracy of history taking to assess lumbosacral nerve root compression

Background contextThe diagnosis of sciatica is primarily based on history and physical examination. Most physical tests used in isolation show poor diagnostic accuracy. Little is known about the diagnostic accuracy of history items.PurposeTo assess the diagnostic accuracy of history taking for the presence of lumbosacral nerve root compression or disc herniation on magnetic resonance imaging in patients with sciatica.Study designCross-sectional diagnostic study.Patient sampleA total of 395 adult patients with severe disabling radicular leg pain of 6 to 12 weeks duration were included.Outcome measuresLumbosacral nerve root compression and disc herniation on magnetic resonance imaging were independently assessed by two neuroradiologists and one neurosurgeon blinded to any clinical information.MethodsData were prospectively collected in nine hospitals. History was taken according to a standardized protocol. There were no study-specific conflicts of interest.ResultsExploring the diagnostic odds ratio of 20 history items revealed a significant contribution in diagnosing nerve root compression for “male sex,” “pain worse in leg than in back,” and “a non-sudden onset.” A significant contribution to the diagnosis of a herniated disc was found for “body mass index <30,” “a non-sudden onset,” and “sensory loss.” Multivariate logistic regression analysis of six history items pre-selected from the literature (age, gender, pain worse in leg than in back, sensory loss, muscle weakness, and more pain on coughing/sneezing/straining) revealed an area under the receiver operating characteristic curve of 0.65 (95% confidence interval, 0.58–0.71) for the model diagnosing nerve root compression and an area under the receiver operating characteristic curve of 0.66 (95% confidence interval, 0.58–0.74) for the model diagnosing disc herniation.ConclusionsA few history items used in isolation had significant diagnostic value and the diagnostic accuracy of a model with six pre-selected items was poor.     

An emerging role for NAADP-mediated Ca2+ signaling in the pancreatic β-cell

Several recent reports, including one in this journal, have reignited the debate about whether the calcium-mobilizing messenger, nicotinic adenine nucleotide diphosphate (NAADP) plays a central role in the regulation of calcium signalling in pancreatic β-cell. These studies have highlighted a role for NAADP-induced Ca(2+) mobilization not only in mediating the effects of the incretin, GLP-1 and the autocrine proliferative effects of insulin, but also possibly a fundamental role in glucose-mediated insulin secretion in the pancreatic β-cell.     

Gut microbiome and bone

The gut microbiome is now viewed as a tissue that interacts bidirectionally with the gastrointestinal, immune, endocrine and nervous systems, affecting the cellular responses in numerous organs. Evidence is accumulating of gut microbiome involvement in a growing number of pathophysiological processes, many of which are linked to inflammatory responses. More specifically, data acquired over the last decade point to effects of the gut microbiome on bone mass regulation and on the development of bone diseases (such as osteoporosis) and of inflammatory joint diseases characterized by bone loss. Mice lacking a gut microbiome have bone mass alteration that can be reversed by gut recolonization. Changes in the gut microbiome composition have been reported in mice with estrogen-deficiency osteoporosis and have also been found in a few studies in humans. Probiotic therapy decreases bone loss in estrogen-deficient animals. The effect of the gut microbiome on bone tissue involves complex mechanisms including modulation of CD4⁺T cell activation, control of osteoclastogenic cytokine production and modifications in hormone levels. This complexity may contribute to explain the discrepancies observed betwwen some studies whose results vary depending on the age, gender, genetic background and treatment duration. Further elucidation of the mechanisms involved is needed. However, the available data hold promise that gut microbiome manipulation may prove of interest in the management of bone diseases.     

Simple risk score to screen for prediabetes: A cross-sectional study from the Qatar Biobank cohort

Aims/IntroductionThe progression from prediabetes to type 2 diabetes is preventable by lifestyle intervention and/or pharmacotherapy in a large fraction of individuals with prediabetes. Our objective was to develop a risk score to screen for prediabetes in the Middle East, where diabetes prevalence is one of the highest in the world.Materials and MethodsIn this cross‐sectional, case–control study, we used data of 4,895 controls and 2,373 prediabetic adults obtained from the Qatar Biobank cohort. Significant risk factors were identified by logistic regression and other machine learning methods. The receiver operating characteristic was used to calculate the area under curve, cut‐off point, sensitivity, specificity, positive and negative predictive values. The prediabetes risk score was developed from data of Qatari citizens, as well as long‐term (≥15 years) residents.ResultsThe significant risk factors for the Prediabetes Risk Score in Qatar were age, sex, body mass index, waist circumference and blood pressure. The risk score ranges from 0 to 45. The area under the curve of the score was 80% (95% confidence interval 78–83%), and the cut‐off point of 16 yielded sensitivity and specificity of 86.2% (95% confidence interval 82.7–89.2%) and 57.9% (95% confidence interval 65.5–71.4%), respectively. Prediabetes Risk Score in Qatar performed equally in Qatari nationals and long‐term residents.ConclusionsPrediabetes Risk Score in Qatar is the first prediabetes screening score developed in a Middle Eastern population. It only uses risk factors measured non‐invasively, is simple, cost‐effective, and can be easily understood by the general public and health providers. Prediabetes Risk Score in Qatar is an important tool for early detection of prediabetes, and can help tremendously in curbing the diabetes epidemic in the region.     

Altered control of the hypothalamo-pituitary-adrenal axis in adult male rats exposed perinatally to food deprivation and/or dehydration

Dehydration, a classic homeostatic stressor in rats, leads to a series of well characterized endocrine responses including stimulation of the hypothalamo-pituitary-adrenal (HPA) axis. In this study, the hypothesis to be tested was that a 50% maternal food restriction (FR50) in late gestation and lactation may have long-term repercussions on HPA axis responsiveness to dehydration in offspring. For this purpose, we studied HPA axis activity in 4-month-old control (C) and perinatally malnourished male rats after a 72-hour water deprivation period. Furthermore, we investigated the long-lasting effects of perinatal maternal malnutrition on the basal activity of the HPA axis. Under basal conditions, rats exposed to perinatal malnutrition showed reduced body weight, enhanced mineralocorticoid receptor (MR) mRNA levels in CA2 and CA3 hippocampal areas, but decreased glucocorticoid receptor (GR) mRNA levels in CA1, CA3 and dentate gyrus (DG) areas. In contrast, the levels of corticotropin-releasing hormone (CRH) and vasopressin (VP) mRNAs in the hypothalamic paraventricular nucleus (PVN) as well as of VP mRNA in the supraoptic nucleus (SON) were unaffected by maternal undernutrition. Expression of proopiomelanocortin (POMC) in the adenohypophysis was significantly enhanced, whereas prohormone convertase-1 (PC1) was not affected. Perinatal malnutrition reduced absolute adrenal weight but did not affect circulating levels of adrenocorticotropin (ACTH), corticosterone and free corticosterone as well as corticosteroid-binding globulin (CBG) binding capacity. Seventy-two hours of dehydration induced a decrease in body weight and CRH mRNA levels in PVN of controls as well as of FR50 rats, but also led to a rise in plasma corticosterone and free corticosterone without changing CBG binding capacity. Dehydration also induced an increase in adenopituitary POMC (C) and PC1 (FR50), PVN and SON VP (C) and GR in CA1 hippocampal area (FR50) mRNA levels and plasma ACTH (C), but a decrease in MR in DG (C) and GR in CA3 and DG (C) mRNA levels. We conclude that maternal food restriction during the perinatal period affects (1) the adult basal activity of the HPA axis with mainly opposite effects on hippocampal MR and GR gene expression and an increase in adenopituitary POMC gene expression, and (2) the responsiveness to water deprivation in adults. In the latter case, the rise in plasma ACTH levels, adenopituitary POMC gene expression, hypothalamic VP gene expression, and the decrease in hippocampal MR gene expression in DG and GR gene expression in CA3 and DG observed in controls are lacking in FR50 rats. In contrast, drastic adenopituitary PC1 gene expression occurred in FR50 rats but not in control animals.