The toxicity of antiprion antibodies is mediated by the flexible tail of the prion protein.

Prion infections cause lethal neurodegeneration. This process requires the cellular prion protein (PrP(C); ref. 1), which contains a globular domain hinged to a long amino-proximal flexible tail. Here we describe rapid neurotoxicity in mice and cerebellar organotypic cultured slices exposed to ligands targeting the α1 and α3 helices of the PrP(C) globular domain. Ligands included seven distinct monoclonal antibodies, monovalent Fab1 fragments and recombinant single-chain variable fragment miniantibodies. Similar to prion infections, the toxicity of globular domain ligands required neuronal PrP(C), was exacerbated by PrP(C) overexpression, was associated with calpain activation and was antagonized by calpain inhibitors. Neurodegeneration was accompanied by a burst of reactive oxygen species, and was suppressed by antioxidants. Furthermore, genetic ablation of the superoxide-producing enzyme NOX2 (also known as CYBB) protected mice from globular domain ligand toxicity. We also found that neurotoxicity was prevented by deletions of the octapeptide repeats within the flexible tail. These deletions did not appreciably compromise globular domain antibody binding, suggesting that the flexible tail is required to transmit toxic signals that originate from the globular domain and trigger oxidative stress and calpain activation. Supporting this view, various octapeptide ligands were not only innocuous to both cerebellar organotypic cultured slices and mice, but also prevented the toxicity of globular domain ligands while not interfering with their binding. We conclude that PrP(C) consists of two functionally distinct modules, with the globular domain and the flexible tail exerting regulatory and executive functions, respectively. Octapeptide ligands also prolonged the life of mice expressing the toxic PrP(C) mutant, PrP(Δ94-134), indicating that the flexible tail mediates toxicity in two distinct PrP(C)-related conditions. Flexible tail-mediated toxicity may conceivably play a role in further prion pathologies, such as familial Creutzfeldt-Jakob disease in humans bearing supernumerary octapeptides.

The Incidence of Hypoglycemia among Insulin-Treated Patients with Type 1 or Type 2 Diabetes: Bangladeshi Cohort of International Operations-Hypoglycemia Assessment Tool Study.

OBJECTIVES: The objective of this study was to assess the incidence of hypoglycemia in patients with type 1 diabetes mellitus (T1DM) or type 2 diabetes mellitus (T2DM) in Bangladeshi cohort of the International Operations-Hypoglycemia Assessment Tool study. MATERIALS AND METHODS: Patients diagnosed with either T1DM or T2DM, aged ≥18 years, treated with insulin (any regimen) for >12 months, and completed self-assessment questionnaires (SAQs) to record demography, treatment information, and hypoglycemia during the 6-month retrospective and 4-week prospective periods (a total of 7 months) were enrolled in the study. RESULTS: A total of 1179 patients were enrolled and completed the SAQ1 (T1DM, n = 25; T2DM, n = 1154). Almost all patients (T1DM: 100.0% [95% confidence interval (CI): 86.3%, 100.0%] and T2DM: 97.0% [95% CI: 95.9%, 97.9%]) experienced at least 1 hypoglycemic event prospectively. The estimated rates of any and severe hypoglycemia were 26.6 (95% CI: 19.8, 35.0) and 14.1 (95% CI: 9.3, 20.4) events per patient-per year (PPY), respectively, for patients with T1DM and 18.3 (95% CI: 17.4, 19.2) and 12.1 (95% CI: 11.4, 12.9) events PPY, respectively, for patients with T2DM during the prospective period. At baseline, mean glycated hemoglobin (HbA1c) (±standard deviation) was 8.1 (±1.8%) for T1DM and 8.8 (±1.8%) for T2DM. Hypoglycemic rate was independent of HbA1c levels and types of insulin. CONCLUSIONS: This is the first patient dataset of self-reported hypoglycemia in Bangladesh; results confirm that hypoglycemia is underreported.

A global study of transcriptome dynamics in canola (Brassica napus L.) responsive to Sclerotinia sclerotiorum infection using RNA-Seq.

The necrotrophic phytopathogen, Sclerotinia sclerotiorum, causes Sclerotinia stem rot, which is a serious constraint to canola (Brassica napus L.) production worldwide. To understand the detailed molecular mechanisms underlying host response to Sclerotinia infection, we analyzed the transcript level changes in canola post-infection with S. sclerotiorum in a time course of a compatible interaction using strand specific whole transcriptome sequencing. Following infection, 161 and 52 genes (P≤0.001) were induced while 24 and 23 genes were repressed at 24h post-inoculation (hpi) and 48hpi, respectively. This suggests that, a gradual increase in host cell lyses and increase virulence of the pathogen led to the expression of only a fewer host specific genes at the later stage of infection. We observed rapid induction of key pathogen responsive genes, including glucanases, chitinases, peroxidases and WRKY Transcription factors (TFs) within 24hpi, indicating early detection of the pathogen by the host. Only 16 genes were significantly induced at both the time points suggesting a coordinated suppression of host responses by the pathogen. In addition to genes involved in plant-pathogen interactions, many novel disease responsive genes, including various TF sand those associated with jasmonate (JA) and ethylene (ET) signalling were identified. This suggests that canola adopts multiple strategies in mediating plant responses to the pathogen attack. Quantitative real time PCR (qRT-PCR) validation of a selected set of genes demonstrated a similar trend as observed by RNA-Seq analysis and highlighted the potential involvement of these genes by the host to defend itself from pathogen attack. Overall, this work presents an in-depth analysis of the interaction between host susceptibility and pathogen virulence in the agriculturally important B. napus-S. sclerotiorum pathosystem.

Expression of anti-sclerotinia scFv in transgenic Brassica napus enhances tolerance against stem rot.

Canola is an important agricultural crop imparting a significant contribution to global oilseed production. As such, optimizing yield and quality is of paramount importance and canola production can be significantly affected by sclerotinia stem rot. The utility of recombinant antibody technology in plant protection has been explored by many researchers and shows promise for the generation of new lines of agriculturally significant crops with greater resistance to diseases. The objective of the current study was to generate recombinant pathogen specific antibody (scFv)-expressing transgenic Brassica napus plants with increased tolerance to the phytopathogenic fungus, Sclerotinia sclerotiorum. Transgenic canola (B. napus) lines expressing S. sclerotiorum-specific scFv antibody showed a significant level of tolerance towards S. sclerotiorum as compared to their non-transformed counterparts. Both incidence and progression of S. sclerotiorum-induced disease symptoms were reduced in plants expressing the recombinant scFv.

Insulin secretion and sensitivity in Bangladeshi prediabetic subjects.

OBJECTIVE: There are still considerable controversies regarding the basic pathophysiological mechanisms of impaired fasting glucose (IFG) and/or impaired glucose tolerance (IGT). The present study was undertaken to explore the beta-cell function and insulin sensitivity in a Bangladeshi prediabetic population. METHODS: Twenty-four IFG and 112 IGT subjects, along with 40 healthy controls, were selected purposively following 2003 ADA cut-off values and 2006 WHO/IDF grouping. IGT subjects were subcategorized into 53 isolated IGT (I-IGT) and 59 combined IFG-IGT subjects. Plasma glucose and insulin (by chemiluminescent immunoassay) were measured at fasting and 2 h after 75 g of oral glucose load. Insulin sensitivity was assessed by homeostasis model assessment (HOMA-S%) and insulin sensitivity index for glycemia (ISI(gly)) and insulin secretion by HOMA-B%. RESULTS: Compared to control, fasting and 2-h plasma insulin were higher in I-IGT and IFG-IGT subjects; similarly, HOMA-S% [median (range)] was lower in I-IGT and IFG-IGT subjects [116 (54-227) vs. 93 (23-187) and 79 (32-197)%, P<.05 and P<.001]; ISI(gly) was also lower in I-IGT and IFG-IGT subjects [0.95 (0.54-1.64) vs. 0.64 (0.26-1.24) and 0.65 (0.29-1.20), P<.001]. But HOMA-B% was compromised in IFG and IFG-IGT groups [88 (59-182) vs. 68 (37-107) and 74 (36-141)%, P<.001 and P<.05]. The IGT group (combination of I-IGT and IFG-IGT) showed higher fasting and 2-h insulin, and lower HOMA-S% as well as ISI(gly), but compromised HOMA-B% was not evident. CONCLUSIONS: The pathophysiological mechanisms differ in IFG (having B-cell dysfunction) and I-IGT (an insulin-resistant condition). The pathophysiology of IFG-IGT (having both B-cell dysfunction and insulin resistance) indicates that it may be a different entity and not be included in IGT.