Publications by authors named "Knoch K"

Background: The efficacy of oncolytic viruses (OV) in cancer treatment depends on their ability to successfully infect and destroy tumor cells. However, patients' tumors vary, and in the case of individual insensitivity to an OV, therapeutic efficacy is limited. Here, we present a protocol for rapid generation of tumor cell-specific adapted oncolytic coxsackievirus B3 (CVB3) with enhanced oncolytic potential and a satisfactory safety profile.

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β cells produce, store, and secrete insulin upon elevated blood glucose levels. Insulin secretion is a highly regulated process. The probability for insulin secretory granules to undergo fusion with the plasma membrane or being degraded is correlated with their age.

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Coxsackievirus B3 (CVB3) has strong oncolytic activity in colorectal carcinoma but it also infects the pancreas and the heart. To improve the safety of the virus, here we investigated whether pancreas and cardiac toxicity can be prevented by insertion of target sites (TS), which are complementary to miR-375 and miR-1 into the viral genome. Although miR-375 and miR-1 are abundantly expressed in the pancreas and in the heart, respectively, their expression levels are low in colorectal carcinomas, which allows the carcinomas to be selectively attacked.

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The discovery of insulin in 1921 has been one of greatest scientific achievements of the 20th century. Since then, the availability of insulin has shifted the focus of diabetes treatment from trying to keep patients alive to saving and improving the life of millions. Throughout this time, basic and clinical research has advanced our understanding of insulin synthesis and action, both in healthy and pathological conditions.

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  • MicroRNAs (miRNAs) are crucial for beta cell function and identity, and this study identifies miRNAs involved in beta cell regeneration after partial pancreatectomy in mice.
  • Researchers used RNA profiling from isolated islets to find specific miRNAs, especially focusing on miR-132, which was upregulated post-surgery, while miR-760 was downregulated.
  • The results show that manipulating miR-132 impacts beta cell proliferation and apoptosis, indicating its potential role in enhancing beta cell regeneration within the pancreas.
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Coxsackievirus B3 (CVB3) has potential as a new oncolytic agent for the treatment of cancer but can induce severe pancreatitis. Here, we inserted target sequences of the microRNA miR-375 (miR-375TS) into the 5' terminus of the polyprotein encoding sequence or into the 3'UTR of the CVB3 strain rCVB3.1 to prevent viral replication in the pancreas.

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Aims: The coxsackievirus B3 (CVB3) mouse myocarditis model is the standard model for investigation of virus-induced myocarditis but the pancreas, rather than the heart, is the most susceptible organ in mouse. The aim of this study was to develop a CVB3 mouse myocarditis model in which animals develop myocarditis while attenuating viral infection of the pancreas and the development of severe pancreatitis.

Methods And Results: We developed the recombinant CVB3 variant H3N-375TS by inserting target sites (TS) of miR-375, which is specifically expressed in the pancreas, into the 3'UTR of the genome of the pancreo- and cardiotropic CVB3 variant H3.

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  • The study developed the first monoclonal antibodies (mABs) for mouse melatonin receptors MT1 and MT2, confirming their reactivity with mouse, rat, and human receptors through various advanced techniques.
  • The antibodies were specifically validated for use in mouse tissues but did not show expression in certain pancreatic cells, making them important tools for future research on melatonin receptor functions.
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  • Type 1 diabetes (T1D) results from an autoimmune attack on insulin-producing β cells in the pancreas, often influenced by environmental factors like viral infections.
  • Recent studies indicate that viral infections may cause β cells to lose their insulin-producing identity instead of killing them.
  • The research shows that a synthetic viral mimic can activate genes associated with progenitor-like cells in β cells, pointing to inflammation's role in cell dedifferentiation in T1D.
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Aims/hypothesis: Pancreatic islet beta cell failure causes type 2 diabetes in humans. To identify transcriptomic changes in type 2 diabetic islets, the Innovative Medicines Initiative for Diabetes: Improving beta-cell function and identification of diagnostic biomarkers for treatment monitoring in Diabetes (IMIDIA) consortium ( www.imidia.

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Insulin secretory granule (SG) turnover consists of several highly regulated processes allowing for proper β-cell function and insulin secretion. Besides the spatial distribution of insulin SGs, their age has great impact on the likelihood of their secretion and their behaviour within the β-cell. While quantitative measurements performed decades ago demonstrated the preferential secretion of young insulin, new experimental approaches aim to investigate insulin ageing at the granular level.

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Objective: Characterization of academic functioning in children with autism spectrum disorder (ASD), particularly predictors of achievement, may have important implications for intervention. The current study aimed to characterize achievement profiles, confirm associations between academic ability and concurrent intellectual and social skills, and explore preschool predictors of school-age academic achievement in a sample of children with ASD.

Method: Children with ASD (n = 26) were evaluated at the approximate ages of two, four, and ten.

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Questions have been raised about the significance of restricted and repetitive behaviors (RRBs) in predicting outcomes of children with Autism Spectrum Disorders (ASDs). Previous studies have yielded mixed findings, but some suggest that the presence of RRBs during preschool years is a negative prognostic indicator for later childhood. This study examined the effect of RRBs at ages 1-2 and 3-5 years on cognitive functioning, adaptive abilities, and ASD symptomatology at age 8-10 years in 40 children with ASDs.

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Type 1 diabetes (T1D) results from genetic predisposition and environmental factors leading to the autoimmune destruction of pancreatic beta cells. Recently, a rapid increase in the incidence of childhood T1D has been observed worldwide; this is too fast to be explained by genetic factors alone, pointing to the spreading of environmental factors linked to the disease. Enteroviruses (EVs) are perhaps the most investigated environmental agents in relationship to the pathogenesis of T1D.

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  • Glucose and GLP-1 enhance insulin secretion and stimulate the creation of insulin granules by promoting the RNA binding protein PTBP1's movement into the nucleus and its interaction with mRNA, which stabilizes them.
  • Glucose also boosts PTBP1's binding to specific regions of mRNAs that allow translation without the typical cap-dependent mechanism, ensuring granule cargo production.
  • Coxsackievirus infection hampers insulin granule stores and secretion by targeting PTBP1, providing insights into how this virus may contribute to type 1 diabetes development.
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Symptoms of autism spectrum disorders may appear as early as 6 months, but parent concern, which can precipitate evaluation, often lags significantly. The presence of typical or atypical older siblings can change parents' sensitivity to departures from typical development. This study investigated type and age of parent's first concerns in toddlers with autism spectrum disorder, prior to diagnosis.

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Aims/hypothesis: Immunosuppressive drugs used in human islet transplantation interfere with the balance between beta cell renewal and death, and thus may contribute to progressive graft dysfunction. We analysed the influence of immunosuppressants on the proliferation of transplanted alpha and beta cells after syngeneic islet transplantation in streptozotocin-induced diabetic mice.

Methods: C57BL/6 diabetic mice were transplanted with syngeneic islets in the liver and simultaneously abdominally implanted with a mini-osmotic pump delivering BrdU alone or together with an immunosuppressant (tacrolimus, sirolimus, everolimus or mycophenolate mofetil [MMF]).

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Objective: Polypyrimidine tract-binding protein 1 (PTBP1) promotes stability and translation of mRNAs coding for insulin secretion granule proteins and thereby plays a role in β-cells function. We studied whether common genetic variations within the PTBP1 locus influence insulin secretion, and/or proinsulin conversion.

Methods: We genotyped 1,502 healthy German subjects for four tagging single nucleotide polymorphisms (SNPs) within the PTBP1 locus (rs351974, rs11085226, rs736926, and rs123698) covering 100% of genetic variation with an r(2)≥0.

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Investigations into the pathogenesis of type 2 diabetes and islets of Langerhans malfunction (1) have been hampered by the limited availability of type 2 diabetic islets from organ donors(2). Here we share our protocol for isolating islets from human pancreatic tissue obtained from type 2 diabetic and non-diabetic patients who have undergone partial pancreatectomy due to different pancreatic diseases (benign or malignant pancreatic tumors, chronic pancreatitis, and common bile duct or duodenal tumors). All patients involved gave their consent to this study, which had also been approved by the local ethics committee.

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Failure of pancreatic β-cells contributes to the development of type 2 diabetes. Besides evidence of reduced glucose-stimulated insulin secretion and β-cell mass, little information is available about the molecular deficits of human diabetic islets. Islets were isolated from macroscopically normal pancreatic tissue from 8 patients with type 2 diabetes and 17 matched non-diabetic patients who underwent pancreatic surgery.

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The molecular basis for the interaction of insulin granules with the cortical cytoskeleton of pancreatic β-cells remains unknown. We have proposed that binding of the granule protein ICA512 to the PDZ domain of β2-syntrophin anchors granules to actin filaments and that the phosphorylation/dephosphorylation of β2-syntrophin regulates this association. Here we tested this hypothesis by analyzing INS-1 cells expressing GFP-β2-syntrophin through the combined use of biochemical approaches, imaging studies by confocal and total internal reflection fluorescence microscopy as well as electron microscopy.

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Glucose and cAMP-inducing agents such as 3-isobutyl-1-methylxanthine (IBMX) rapidly change the expression profile of insulin-producing pancreatic beta-cells mostly through post-transcriptional mechanisms. A thorough analysis of these changes, however, has not yet been performed. By combining two-dimensional differential gel electrophoresis and mass spectrometry, we identified 165 spots, corresponding to 78 proteins, whose levels significantly change after stimulation of the beta-cell model INS-1 cells with 25 mM glucose + 1 mM IBMX for 2 h.

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Changes in metabolic demands dynamically regulate the total mass of adult pancreatic beta-cells to adjust insulin secretion and preserve glucose homeostasis. Glucose itself is a major regulator of beta-cell proliferation by inducing insulin secretion and activating beta-cell insulin receptors. Here, we show that islet cell autoantigen 512 (ICA512)/IA-2, an intrinsic tyrosine phosphatase-like protein of the secretory granules, activates a complementary pathway for beta-cell proliferation.

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Glucose stimulates the exocytosis of insulin secretory granules of pancreatic beta cells. Granule stores are quickly refilled by activation of posttranscriptional mechanisms that enhance the biosynthesis of granule components. Rapid replacement of granules is important to sustain insulin secretion, since new granules appear to be preferentially released.

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One impediment for a wider application of islet transplantation is the limited number of donor pancreata for islet isolation. A more efficient utilization of available organs could in part alleviate this problem. Perfluorocarbons (PFCs) have a high oxygen solubility coefficient and maintain high oxygen partial pressures for extended time.

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