80 research outputs found

    Optimization of insect cell based protein production processes - online monitoring, expression systems, scale-up

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    Due to the increasing use of insect cell based expression systems in research and industrial recombinant protein production, the development of efficient and reproducible production processes remains a challenging task. In this context, the application of online monitoring techniques is intended to ensure high and reproducible product qualities already during the early phases of process development. In the following chapter, the most common transient and stable insect cell based expression systems are briefly introduced. Novel applications of insect cell based expression systems for the production of insect derived antimicrobial peptides/proteins (AMPs) are discussed using the example of G. mellonella derived gloverin. Suitable in situ sensor techniques for insect cell culture monitoring in disposable and common bioreactor systems are outlined with respect to optical and capacitive sensor concepts. Since scale-up of production processes is one of the most critical steps in process development, a conclusive overview is given about scale up aspects for industrial insect cell culture processes

    The Intrinsic Substrate Specificity of the Human Tyrosine Kinome

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    Phosphorylation of proteins on tyrosine (Tyr) residues evolved in metazoan organisms as a mechanism of coordinating tissue growth1. Multicellular eukaryotes typically have more than 50 distinct protein Tyr kinases that catalyse the phosphorylation of thousands of Tyr residues throughout the proteome1-3. How a given Tyr kinase can phosphorylate a specific subset of proteins at unique Tyr sites is only partially understood4-7. Here we used combinatorial peptide arrays to profile the substrate sequence specificity of all human Tyr kinases. Globally, the Tyr kinases demonstrate considerable diversity in optimal patterns of residues surrounding the site of phosphorylation, revealing the functional organization of the human Tyr kinome by substrate motif preference. Using this information, Tyr kinases that are most compatible with phosphorylating any Tyr site can be identified. Analysis of mass spectrometry phosphoproteomic datasets using this compendium of kinase specificities accurately identifies specific Tyr kinases that are dysregulated in cells after stimulation with growth factors, treatment with anti-cancer drugs or expression of oncogenic variants. Furthermore, the topology of known Tyr signalling networks naturally emerged from a comparison of the sequence specificities of the Tyr kinases and the SH2 phosphotyrosine (pTyr)-binding domains. Finally we show that the intrinsic substrate specificity of Tyr kinases has remained fundamentally unchanged from worms to humans, suggesting that the fidelity between Tyr kinases and their protein substrate sequences has been maintained across hundreds of millions of years of evolution

    Isolation of a euryhaline microalgal strain, Tetraselmis sp CTP4, as a robust feedstock for biodiesel production

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    Bioprospecting for novel microalgal strains is key to improving the feasibility of microalgae-derived biodiesel production. Tetraselmis sp. CTP4 (Chlorophyta, Chlorodendrophyceae) was isolated using fluorescence activated cell sorting (FACS) in order to screen novel lipid-rich microalgae. CTP4 is a robust, euryhaline strain able to grow in seawater growth medium as well as in non-sterile urban wastewater. Because of its large cell size (9-22 mu m), CTP4 settles down after a six-hour sedimentation step. This leads to a medium removal efficiency of 80%, allowing a significant decrease of biomass dewatering costs. Using a two-stage system, a 3-fold increase in lipid content (up to 33% of DW) and a 2-fold enhancement in lipid productivity (up to 52.1 mg L-1 d(-1)) were observed upon exposure to nutrient depletion for 7 days. The biodiesel synthesized from the lipids of CTP4 contained high levels of oleic acid (25.67% of total fatty acids content) and minor amounts of polyunsaturated fatty acids with >= 4 double bonds (< 1%). As a result, this biofuel complies with most of the European (EN14214) and American (ASTM D6751) specifications, which commonly used microalgal feedstocks are usually unable to meet. In conclusion, Tetraselmis sp. CTP4 displays promising features as feedstock with lower downstream processing costs for biomass dewatering and biodiesel refining

    Gene Expression Analysis of Forskolin Treated Basilar Papillae Identifies MicroRNA181a as a Mediator of Proliferation

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    Auditory hair cells spontaneously regenerate following injury in birds but not mammals. A better understanding of the molecular events underlying hair cell regeneration in birds may allow for identification and eventually manipulation of relevant pathways in mammals to stimulate regeneration and restore hearing in deaf patients.Gene expression was profiled in forskolin treated (i.e., proliferating) and quiescent control auditory epithelia of post-hatch chicks using an Affymetrix whole-genome chicken array after 24 (n = 6), 48 (n = 6), and 72 (n = 12) hours in culture. In the forskolin-treated epithelia there was significant (p<0.05; >two-fold change) upregulation of many genes thought to be relevant to cell cycle control and inner ear development. Gene set enrichment analysis was performed on the data and identified myriad microRNAs that are likely to be upregulated in the regenerating tissue, including microRNA181a (miR181a), which is known to mediate proliferation in other systems. Functional experiments showed that miR181a overexpression is sufficient to stimulate proliferation within the basilar papilla, as assayed by BrdU incorporation. Further, some of the newly produced cells express the early hair cell marker myosin VI, suggesting that miR181a transfection can result in the production of new hair cells.These studies have identified a single microRNA, miR181a, that can cause proliferation in the chicken auditory epithelium with production of new hair cells

    Seroepidemiology of Varicella and value of self-reported history of Varicella infection in Iranian medical students

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    Objectives: We conducted this study to assess the seroprevalence of Varicella zoster virus (VZV) antibodies in a group of Iranian medical sciences students that were at risk of Varicella and the value of self-reported history as a predictor of immunity. Material and Methods: 255 medical, nursing and obstetrics students who had not entered as a student or worked in a hospital from 3 different schools were enrolled in the study in 2012 (Qazvin province, Iran). Demographics and other information as well as the history of Varicella were obtained through a self-administered questionnaire. Blood samples were collected to determine the Varicella IgG levels via an enzyme-linked immunosorbent assay. A statistical analysis was performed by calculating prevalences and their 95% confidence intervals. Sensitivity, specificity, positive and negative predictive values, Cohen's kappa and positive and negative likelihood ratios of recalled history were determined. p < 0.05 was considered statistically significant. Results: The mean age of participants was 21.3±4.3 years. Seropositivity rate was 74.5%. The relationships between marital status, number of family members, and acquired VZV history with immunity against the virus were statistically significant. The overall rate of reported history was 57%. The positive and negative predictive values of self-reported history of Varicella were 91% and 47.3%, respectively. Conclusions: Immunization of students of Iranian medical sciences seems logical in the near future. Also, they should be tested for Varicella immunity regardless of the history of previous infection

    Gaps in osmolal gap: A case of mistaken osmolal gap in a patient with diabetic ketoacidosis.

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    Introduction: The presence of an osmolal gap is often used as an aide to detect osmotically active substances like toxic alcohol. However, inappropriately calculated osmolality in hypertonic hyponatremia in the setting of diabetic ketoacidosis (DKA) can falsely elevate the osmolal gap resulting in inappropriate management decisions. Case Presentation: A 64-year-old male known to have history of alcohol abuse and recurrent pancreatitis presented to the emergency room with nausea, vomiting and abdominal pain of 3-days duration. His vital signs were notable for a normal blood pressure (97/73 mm of hg), tachycardia (140 bpm), temperature of 36.6 °C, tachypnea (32 beats/min) and a normal oxygen saturation (97%). He was found to have dry mucous membranes, and slowed mentation on physical examination. Pertinent laboratory data revealed a BUN of 66 mg/dl, creatinine of 3.47 mg/dl, sodium of 133 mmol/dl, potassium of 4.6 mmol/dl, bicarbonate 5 meq/dl, beta hydroxybutyrate of 19 mmol/L and an elevated serum glucose (1290 mg/dl). His calculated anion gap was 46. Patient\u27s serum alcohol and standard urine drug screen were negative. His measured serum osmolality was 406 mOs/kg. Patient was erroneously thought to have an osmolal gap of 45 mOs/kg. This was due to incorrect derivation of calculated osmolality without factoring in for hyperglycemia. In lieu of a severely elevated osmolal gap, a volatile alcohol screen was sent. He was started on fomepizole and transferred to the intensive care unit (ICU). In the ICU, his osmolal gap was re-evaluated, but now accounting for hyperglycemia, corrected sodium was 152 meq/dl thus an osmolality of 399 mOs/Kg yielding a normal osmolal gap (7 mOs/Kg). Fomepizole was discontinued and therapy target to treat his DKA. Subsequently, the patient\u27s volatile alcohol screening was positive for only acetone. Discussion: This case illustrates key pathophysiology that influences the interpretation of an osmolal gap. An error prone step in assessing the osmolal gap in DKA is to omit the correction factor for translocational hyponatremia in DKA. Another key concept is to recognize that an osmolal gap is not an unusual finding in DKA and should not be confused for the presence of toxic alcohols. An osmolal gap in DKA is attributable to the metabolism of beta-hydroxybutrate to acetone by way of acetoacetate. Acetone, being electrochemically inactive, does not alter the anion gap but imparts osmolality. Our patient underscores the importance of recognizing the limitation and varying etiology of an elevated osmolal gap that could avert management pitfalls
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