Detection of prion protein in urine-derived injectable fertility products by a targeted proteomic approach

A semi-automated hybrid HPLC-MS approach for in-depth characterization of intact non-covalent heterodimer glycoforms of gonadotropin biopharmaceuticals

BACKGROUND

Gonadotropins are a class of heavily glycosylated protein hormones, thus extremely challenging to characterize by mass spectrometry. As biopharmaceuticals, gonadotropins are prescribed for the treatment of infertility and are derived from different sources: either from pooled urine of pregnant women or upon production in genetically modified Chinese Hamster Ovary cells. Human chorionic gonadotropin (hCG) is sold as a biopharmaceutical under the name Pregnyl® (urinary hCG, u-hCG) and Ovitrelle® (recombinant hCG, r-hCG), and recombinant human follicle stimulating hormone (r-hFSH) is marketed as Gonal-f®. Recently, we reported the exhaustive characterization of r-hCG at different structural levels.

RESULTS

We implement size exclusion (SE) HPLC-MS to automatize the acquisition of native mass spectra of r-hCG dimer, but also u-hCG and r-hFSH, comparing the drug products up to intact heterodimer level. A hybrid HPLC-MS approach was employed for the characterization of r-hCG, u-hCG and r-hFSH drug products at different structural levels. Released glycans were analyzed by porous graphitized carbon (PGC)-HPLC-MS/MS, glycopeptides by reversed-phase (RP)-HPLC-MS/MS, subunits by RP-HPLC-MS and finally the intact native heterodimers by semi-automated online buffer exchange SE-HPLC-MS. The data were integrated using bioinformatic tools, to finally unravel the composition of 1481 co-existing dimeric glycoforms for r-hCG, 1167 glycoforms for u-hCG, and 1440 glycoforms for r-hFSH, and to compare critical quality attributes of the different drug products such as their degree of sialylation and O-glycosylation.

SIGNIFICANCE AND NOVELTY

The strong alliance of bioanalytics and bioinformatics data integration at the different structural levels allowed the identification of more than thousand different glycoforms of r-hCG, u-hCG, and r-hFSH. The results showed that these biopharmaceuticals differ considerably in their glycosylation patterns and highlight the importance of in-depth characterization of biopharmaceuticals for quality control. © 2017 Elsevier Inc. All rights reserved.

Principles of risk decision-making

Risk management decisions in public health require consideration of a number of complex, often conflicting factors. The aim of this review was to propose a set of 10 fundamental principles to guide risk decision-making. Although each of these principles is sound in its own right, the guidance provided by different principles might lead the decision-maker in different directions. For example, where the precautionary principle advocates for preemptive risk management action under situations of scientific uncertainty and potentially catastrophic consequences, the principle of risk-based decision-making encourages decision-makers to focus on established and modifiable risks, where a return on the investment in risk management is all but guaranteed in the near term. To evaluate the applicability of the 10 principles in practice, one needs to consider 10 diverse risk issues of broad concern and explore which of these principles are most appropriate in different contexts. The 10 principles presented here afford substantive insight into the process of risk management decision-making, although decision-makers will ultimately need to exercise judgment in reaching appropriate risk decisions, accounting for all of the scientific and extra-scientific factors relevant to the risk decision at hand.

Prion Dissemination through the Environment and Medical Practices: Facts and Risks for Human Health

Prion diseases are a group of fatal, infectious neurodegenerative disorders affecting various species of mammals, including humans. The infectious agent in these diseases, termed prion, is composed exclusively of a misfolded protein that can spread and multiply in the absence of genetic materials. In this article, we provide an overview of the mechanisms of prion replication, interindividual transmission, and dissemination in communities. In particular, we review the potential role of the natural environment in prion transmission, including the mechanisms and pathways for prion entry and accumulation in the environment as well as its roles in prion mutation, adaptation, evolution, and transmission. We also discuss the transmission of prion diseases through medical practices, scientific research, and use of biological products. Detailed knowledge of these aspects is crucial to limit the spreading of existing prion diseases as well as to prevent the emergence of new diseases with possible catastrophic consequences for public health.

CHORIONIC GONADOTROPINE: STRUCTURAL HETEROGENEITY, METABOLIC PATHWAY, FUNCTIONS, OBTAINING AND POSSIBILITIES OF CLINICAL APPLICATION

Human chorionic gonadotropin (hCG) is one of the key hormones needed for pregnancy sustaining. At the same time, it performs many other biological functions, which is due to the effect on the immune cells’ activity, the ability to bind to at least three types of receptors and activate various signaling cascades. Several structural forms of hCG and their combinations have been identified. This structural heterogeneity is the cause of variations not only in the degree and direction of the hormone functional activity, but in the mechanisms of its action, the degree of binding to other molecules and the conditions of dissociation as well. Aim. To review the current understanding of the role and mechanisms of the biological activity of hCG and its isoforms, as well as the identification of physicochemical factors that affect the completeness of hCG release from biological raw materials and the stability of the isolated drug during further storage. Methods. A computerized literature search was performed using three electronic databases from 1980 to 2020. Descriptive and comparative analyzes were performed for discovered studies in molecular biology, biochemistry and clinical practice. Results. A detailed biochemical and physiological analysis of hCG and its related molecules are provided in this review. The features of measuring its content in tissues, isolation and purification methods, difficulties associated with low-temperature storage, as well as the spectrum of hCG preparations clinical use of and their proposed new therapeutic possibilities are considered. Conclusions. HCG is characterized by a wide range of versatile functions, and its field of application in laboratory diagnostics and clinical practice is still expanding. At the same time, to elucidate the mechanisms of its multiple therapeutic effects, including antitumor action, as well as the mechanisms of dissociation under conditions of low-temperature storage, which can solve the problem of maintaining the stability of this hormone, it remains relevant.

The importance of ongoing international surveillance for Creutzfeldt-Jakob disease

Creutzfeldt-Jakob disease (CJD) is a rapidly progressive, fatal and transmissible neurodegenerative disease associated with the accumulation of misfolded prion protein in the CNS. International CJD surveillance programmes have been active since the emergence, in the mid-1990s, of variant CJD (vCJD), a disease linked to bovine spongiform encephalopathy. Control measures have now successfully contained bovine spongiform encephalopathy and the incidence of vCJD has declined, leading to questions about the requirement for ongoing surveillance. However, several lines of evidence have raised concerns that further cases of vCJD could emerge as a result of prolonged incubation and/or secondary transmission. Emerging evidence from peripheral tissue distribution studies employing high-sensitivity assays suggests that all forms of human prion disease carry a theoretical risk of iatrogenic transmission. Finally, emerging diseases, such as chronic wasting disease and camel prion disease, pose further risks to public health. In this Review, we provide an up-to-date overview of the transmission of prion diseases in human populations and argue that CJD surveillance remains vital both from a public health perspective and to support essential research into disease pathophysiology, enhanced diagnostic tests and much-needed treatments.

Improving the Predictive Value of Prion Inactivation Validation Methods to Minimize the Risks of Iatrogenic Transmission With Medical Instruments

Prions are pathogenic infectious agents responsible for fatal, incurable neurodegenerative diseases in animals and humans. Prions are composed exclusively of an aggregated and misfolded form (PrP^Sc) of the cellular prion protein (PrP^C). During the propagation of the disease, PrP^Sc recruits and misfolds PrP^C into further PrP^Sc. In human, iatrogenic prion transmission has occurred with incompletely sterilized medical material because of the unusual resistance of prions to inactivation. Most commercial prion disinfectants validated against the historical, well-characterized laboratory strain of 263K hamster prions were recently shown to be ineffective against variant Creutzfeldt-Jakob disease human prions. These observations and previous reports support the view that any inactivation method must be validated against the prions for which they are intended to be used. Strain-specific variations in PrP^Sc physico-chemical properties and conformation are likely to explain the strain-specific efficacy of inactivation methods. Animal bioassays have long been used as gold standards to validate prion inactivation methods, by measuring reduction of prion infectivity. Cell-free assays such as the real-time quaking-induced conversion (RT-QuIC) assay and the protein misfolding cyclic amplification (PMCA) assay have emerged as attractive alternatives. They exploit the seeding capacities of PrP^Sc to exponentially amplify minute amounts of prions in biospecimens. European and certain national medicine agencies recently implemented their guidelines for prion inactivation of non-disposable medical material; they encourage or request the use of human prions and cell-free assays to improve the predictive value of the validation methods. In this review, we discuss the methodological and technical issues regarding the choice of (i) the cell-free assay, (ii) the human prion strain type, (iii) the prion-containing biological material. We also introduce a new optimized substrate for high-throughput PMCA amplification of human prions bound on steel wires, as translational model for prion-contaminated instruments.

Detection of Pathognomonic Biomarker PrPSc and the Contribution of Cell Free-Amplification Techniques to the Diagnosis of Prion Diseases

Transmissible spongiform encephalopathies or prion diseases are rapidly progressive neurodegenerative diseases, the clinical manifestation of which can resemble other promptly evolving neurological maladies. Therefore, the unequivocal ante-mortem diagnosis is highly challenging and was only possible by histopathological and immunohistochemical analysis of the brain at necropsy. Although surrogate biomarkers of neurological damage have become invaluable to complement clinical data and provide more accurate diagnostics at early stages, other neurodegenerative diseases show similar alterations hindering the differential diagnosis. To solve that, the detection of the pathognomonic biomarker of disease, PrP^Sc, the aberrantly folded isoform of the prion protein, could be used. However, the amounts in easily accessible tissues or body fluids at pre-clinical or early clinical stages are extremely low for the standard detection methods. The solution comes from the recent development of in vitro prion propagation techniques, such as Protein Misfolding Cyclic Amplification (PMCA) and Real Time-Quaking Induced Conversion (RT-QuIC), which have been already applied to detect minute amounts of PrP^Sc in different matrixes and make early diagnosis of prion diseases feasible in a near future. Herein, the most relevant tissues and body fluids in which PrP^Sc has been detected in animals and humans are being reviewed, especially those in which cell-free prion propagation systems have been used with diagnostic purposes.

Human chorionic gonadotrophin pharmaceutical formulations of urinary origin display high levels of contaminant proteins-A label-free quantitation proteomics study

To determine whether there is a measurable protein background in different formulations of urinary and recombinant human chorionic gonadotropin (hCG). Primary outcome measures: identification of contaminant proteins in urinary-derived formulations of hCG; secondary outcome measures: quantitative values of contaminant proteins in different batches of urinary -derived hCG formulations. It was found that urinary-derived batches have high presence of contaminant proteins beside the active substance. The relative amount of contaminant proteins and hCG differs strongly between different batches.

Human Chorionic Gonadotropin as a Pivotal Endocrine Immune Regulator Initiating and Preserving Fetal Tolerance

The pregnancy hormone, human chorionic gonadotropin (hCG), is crucially involved in processes such as implantation and placentation, two milestones of pregnancy whose successful progress is a prerequisite for adequate fetal growth. Moreover, hCG determines fetal fate by regulating maternal innate and adaptive immune responses allowing the acceptance of the foreign fetal antigens. As one of the first signals provided by the embryo to its mother, hCG has the potential to regulate very early pregnancy-driven immune responses, allowing the establishment and preservation of fetal tolerance. This mini review focuses on how hCG modulates the adaptive arm of the immune system including dendritic cells as key regulators of adaptive immune responses.

A Comparison of Outcomes from In Vitro Fertilization Cycles Stimulated with Follicle Stimulating Hormone Plus either Recombinant Luteinizing Hormone or Human Menopausal Gonadotropins in Subjects Treated with Long Gonadotropin Releasing Hormone Agonist Protocols

BACKGROUND

This study compared rates of pregnancy and in vitro fertilization (IVF) parameters in subjects stimulated with follicle stimulating hormone (FSH) plus either recombinant human luteinizing hormone (r-LH) or human menopausal gonadotropin (hMG) in a long gonadotropin releasing hormone (GnRH) agonist IVF protocol.

MATERIALS AND METHODS

This cohort study enrolled patients who underwent IVF stimu- lation with a long GnRH agonist protocol and received FSH plus r-LH or hMG. Outcomes measured included: FSH and LH doses, number of oocytes and embryos obtained, pregnancy rate per cycle, and clinical pregnancy rate per cycle. Stepwise logistic regression was performed on continuous and categorical variables to control for confounding effects between all variables analyzed.

RESULTS

There were 122 patients who underwent 122 IVF cycles with long GnRH agonist protocols. Similar baseline parameters existed between groups. Patients that received r-LH required a lower FSH dose (3207 ± 1300 IU) for stimulation compared to the group that received hMG (4213 ± 1576 IU, P=0.0001). The LH dose was also lower in these patients (1332 ± 587 IU) compared to the patients who received hMG (1938 ± 1110 IU, P=0.0001). The number of days of stimulation did not differ between groups (P=1.0). The group that received r-LH also had statistically higher numbers of oocytes (14.4 ± 6.3) and embryos (7.9 ± 4.8) compared to the hMG group with 11.0 ± 5.3 oocytes and 6.0 ± 3.7 embryos. Pregnancy rates per cycle start were higher for patients in the r-LH group (49%) compared to the hMG group (27%, P=0.025). Patients that received r-LH had higher implantation rates (62%) compared to the hMG group (33%, P=0.001). The r-LH group had a higher trend toward clinical pregnancy rates per cycle start (39%) compared to the hMG group (25%, P=0.065).

CONCLUSION

r-LH may offer benefits compared to hMG when combined with FSH for ovarian stimulation in long GnRH agonist protocols in good responders. Prospective studies should be undertaken to confirm these results.

Diagnosing Sporadic Creutzfeldt-Jakob Disease by the Detection of Abnormal Prion Protein in Patient Urine

IMPORTANCE

Creutzfeldt-Jakob disease (CJD) is a fatal neurodegenerative disorder associated with the accumulation of infectious abnormal prion protein through a mechanism of templated misfolding. A recent report has described the detection of abnormal prion protein in the urine of patients with variant CJD (vCJD) using protein misfolding by cyclic amplification, which was apparently absent in the more common sporadic form of CJD (sCJD). A noninvasive diagnostic test could improve early diagnosis of sCJD and, by screening donations, mitigate the potential risks of prion transmission through human urine-derived pharmaceuticals. Here, we describe the adaptation of the direct detection assay, developed originally as a blood test for vCJD, for the detection of disease-associated prion protein in urine samples from patients with sCJD.

OBJECTIVE

To determine the feasibility of sCJD diagnosis by adaptation of an established vCJD diagnostic blood test to urine.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective, cross-sectional study included anonymized urine samples from healthy nonneurological control individuals (n = 91), patients with non-prion neurodegenerative diseases (n = 34), and patients with prion disease (n = 37) of which 20 had sCJD. Urine samples obtained during the Medical Research Council PRION-1 Trial, the National Prion Monitoring Cohort Study, and/or referred to the National Prion Clinic or Dementia Research Centre at the National Hospital for Neurology and Neurosurgery in the United Kingdom.

MAIN OUTCOMES AND MEASURES

Presence of sCJD infection determined by an assay that captures, enriches, and detects disease-associated prion protein isoforms.

RESULTS

A total of 162 samples were analyzed, composed of 91 normal control individuals (51 male, 33 female, and 7 not recorded), 34 neurological disease control individuals (19 male and 15 female), and 37 with prion disease (22 male and 15 female). The assay's specificity for prion disease was 100% (95% CI, 97%-100%), with no false-positive reactions from 125 control individuals, including 34 from a range of neurodegenerative diseases. In contrast to a previous study, which used a different method, sensitivity to vCJD infection was low (7.7%; 95% CI, 0.2%-36%), with only 1 of 13 patients with positive test results, while sensitivity to sCJD was unexpectedly high at 40% (95% CI, 19%-64%).

CONCLUSIONS AND RELEVANCE

We determined 40% of sCJD urine sample results as positive. To our knowledge, this is the first demonstration of an assay that can detect sCJD infection in urine or any target analyte outside of the central nervous system. Urine detection could allow the development of rapid, molecular diagnostics for sCJD and has implications for other neurodegenerative diseases where disease-related assemblies of misfolded proteins might also be present in urine.

Quantitative analysis of hIgG1 in monkey serum by LC–MS/MS using mass spectrometric immunoassay

Aim: A sensitive generic LC–MS/MS method for hIgG1 quantification in cynomolgus monkey serum using mass spectrometric immunoassay disposable automation research tips (MSIA-D.A.R.T.'S™) is reported. Results: The hIgG1 was captured with a biotinylated mouse anti-hIgG antibody (50.0 µg/ml) targeting the fragment crystallizable (Fc) region. Elution from the streptavidin-coated MSIA-D.A.R.T.'s was conducted with 0.4% trifluoroacetic acid in water. The method was selective and linear from 10.0 to 1000 ng/ml using 100 µl of serum. The method was evaluated regarding accuracy, precision, carry-over, dilution, auto-sampler stability and applied for the determination of hIgG1 concentration in monkey serum after intravitreal administration. Conclusion: The present assay is suitable for quantitative analysis of hIgG1-based therapeutic proteins in monkey serum at low levels.

Proteomics applications in prion biology and structure

Prion diseases are a heterogeneous class of fatal neurodegenerative disorders associated with misfolding of host cellular prion protein (PrP(C)) into a pathological isoform, termed PrP(Sc). Prion diseases affect various mammals, including humans, and effective treatments are not available. Prion diseases are distinguished from other protein misfolding disorders - such as Alzheimer's or Parkinson's disease - in that they are infectious. Prion diseases occur sporadically without any known exposure to infected material, and hereditary cases resulting from rare mutations in the prion protein have also been documented. The mechanistic underpinnings of prion and other neurodegenerative disorders remain poorly understood. Various proteomics techniques have been instrumental in early PrP(Sc) detection, biomarker discovery, elucidation of PrP(Sc) structure and mapping of biochemical pathways affected by pathogenesis. Moving forward, proteomics approaches will likely become more integrated into the clinical and research settings for the rapid diagnosis and characterization of prion pathogenesis.

Absence of TGF-β Receptor Activation by Highly Purified hCG Preparations

Recently, several LH/human chorionic gonadotropin (hCG) receptor-independent activities for hCG have been described, including activation of the TGF-β receptor (TGFβR) by hyperglycosylated hCG and stimulation of trophoblast invasion. Because the hCG concentrations used in these studies have been rather high, reflecting physiological hCG levels in pregnancy, even a minor contamination with growth factors, which act at very low concentrations, may be significant. Several commercial hCG preparations have been found to contain significant amounts of epidermal growth factor (EGF), which we also confirmed here. Furthermore, we found that some hCG preparations also contain significant amounts of TGF-β1. These hCG preparations were able to activate ERK1/2 in JEG-3 choriocarcinoma cells or TGFβR in mink lung epithelial cells transfected with a reporter gene for TGFβR activation. No such activation was found with highly purified hCG or its free β-subunit (hCGβ), irrespective of whether they were hyperglycosylated or not. Taken together, our results suggest that the growth factor contaminations in the hCG preparations can cause activation of TGFβR and, at least in JEG-3 cells, MAPK signaling. This highlights the importance to carefully control for potential contaminations and that highly purified hCG preparations have to be used for biological studies.

Magnetic microparticle-based multimer detection system for the detection of prion oligomers in sheep

Transmissible spongiform encephalopathies (TSEs) are zoonotic fatal neurodegenerative diseases in animals and humans. TSEs are commonly known as bovine spongiform encephalopathy in cattle, scrapie in sheep and goats, chronic wasting disease in cervids, and Creutzfeldt–Jakob disease in humans. The putative transmissible agents are infectious prion proteins (PrP^Sc), which are formed by the conversion of the normal prion protein on the glycoprotein cell surface in the presence of other PrP^Sc. Reports of the transmission of TSEs through blood raised considerable concern about the safety of blood and blood products. To address this issue, many laboratories attempted to develop a sensitive and accurate blood diagnostic test to detect PrP^Sc. Previously, we reported that, compared to normal controls, the multimer detection system (MDS) was more efficient in detecting PrP^Sc in infected hamster brain homogenate, mouse plasma spiked with purified PrP^Sc from scrapie mouse brain, and scrapie-infected hamster plasmas. MDS differentiates prion multimers from the cellular monomer through the multimeric expression of epitopes on prion multimers, in contrast to the monomeric form. In this study, MDS detected PrP^Sc in plasma samples from scrapie-infected sheep expressing clinical symptoms, demonstrating 100% sensitivity and specificity in these samples. Plasma samples from asymptomatic lambs at the preclinical stage (8-month-old naturally infected offspring of scrapie-infected parents expressing a highly susceptible genotype) tested positive with 50% sensitivity and 100% specificity. In the first of two coded analyses using clinical scrapie-infected sheep and normal healthy samples, MDS successfully identified all but one of the clinical samples with 92% sensitivity and 100% specificity. Similar results were obtained in the second coded analysis using preclinical samples. MDS again successfully identified all but one of the samples with 87% sensitivity and 100% specificity. The false-negative sample was subjected to a protease pretreatment. In conclusion, MDS could accurately detect scrapie in plasma samples at both preclinical and clinical stages. From these studies, we conclude that MDS could be a promising tool for the early diagnosis of TSEs from blood samples.

Managing infertility with the follitropin alfa prefilled pen injector - patient considerations

Gonadotropin treatment has been used in fertility treatment since the 1930s. First, preparations coming from animals were injected, then, gonadotropins prepared from the pituitary glands of human cadavers. A great step was achieved with the introduction of human menopausal gonadotropin extracted from the urine of postmenopausal women. When cases of Creutzfeld-Jacob disease were recognized after the use of human pituitary-derived hormone injections, urinary gonadotropins were increasingly purified and then produced by the use of recombinant DNA technology. Recombinant gonadotropins were characterized by the extreme high specificity and the nearly 100% purity. This allows for follitropin alfa, the first recombinant-human follicle stimulating hormone (r-hFSH) approved, to be quantified and filled by mass, with a small variance of only ±2% and no more with a bioassay with a variance of 45%. With recombinant preparations, it is also possible to cover the tremendous growing demand for gonadotropins. Ovarian stimulation has become a self-injecting procedure for the patients. Accurate and easy-to-use injection devices which minimize pain, difficulty, and stress are essential for patient compliance. So, two pen injectors adapted from the well-known insulin pen were introduced in fertility treatment, one as a multiple-use device rechargeable with premixed, prefilled cartridges with r-hFSH (follitropin β) and the other a disposable, prefilled drug delivery system with a liquid formulation of follitropin alfa filled by mass. The efficacy in comparison to the quite more cumbersome handling with ampoules and syringes has been proven very quickly. In several studies, it has been shown that patients had a preference to the prefilled follitropin alfa pen due to the faster preparation and were more confident of accurate dosing. The follitropin alfa (filled by mass [FbM]) prefilled pen is a move toward better quality of treatment and also better quality of life for the women within the stressful period of fertility treatment.

Applying the tools of chemistry (mass spectrometry and covalent modification by small molecule reagents) to the detection of prions and the study of their structure

Prions are molecular pathogens, able to convert a normal cellular prion protein (PrP(C)) into a prion (PrP(Sc)). The information necessary for this conversion is contained in the conformation of PrP(Sc). Mass spectrometry (MS) and small-molecule covalent reactions have been used to study prions. Mass spectrometry has been used to detect and quantitate prions in the attomole range (10⁻¹⁸ mole). MS-based analysis showed that both possess identical amino acid sequences, one disulfide bond, a GPI anchor, asparagine-linked sugar antennae, and unoxidized methionines. Mass spectrometry has been used to define elements of the secondary and tertiary structure of wild-type PrP(Sc) and GPI-anchorless PrP(Sc). It has also been used to study the quaternary structure of the PrP(Sc) multimer. Small molecule reagents react differently with the same lysine in the PrP(C) conformation than in the PrP(Sc) conformation. Such differences can be detected by Western blot using mAbs with lysine-containing epitopes, such as 3F4 and 6D11. This permits the detection of PrP(Sc) without the need for proteinase K pretreatment and can be used to distinguish among prion strains. These results illustrate how two important chemical tools, mass spectrometry and covalent modification by small molecules, are being applied to the detection and structural study of prions. Furthermore these tools are or can be applied to the study of the other protein misfolding diseases such as Alzheimer Disease, Parkinson Disease, or ALS.

Prion protein promotes kidney iron uptake via its ferrireductase activity

Brain iron-dyshomeostasis is an important cause of neurotoxicity in prion disorders, a group of neurodegenerative conditions associated with the conversion of prion protein (PrP(C)) from its normal conformation to an aggregated, PrP-scrapie (PrP(Sc)) isoform. Alteration of iron homeostasis is believed to result from impaired function of PrP(C) in neuronal iron uptake via its ferrireductase activity. However, unequivocal evidence supporting the ferrireductase activity of PrP(C) is lacking. Kidney provides a relevant model for this evaluation because PrP(C) is expressed in the kidney, and ∼370 μg of iron are reabsorbed daily from the glomerular filtrate by kidney proximal tubule cells (PT), requiring ferrireductase activity. Here, we report that PrP(C) promotes the uptake of transferrin (Tf) and non-Tf-bound iron (NTBI) by the kidney in vivo and mainly NTBI by PT cells in vitro. Thus, uptake of (59)Fe administered by gastric gavage, intravenously, or intraperitoneally was significantly lower in PrP-knock-out (PrP(-/-)) mouse kidney relative to PrP(+/+) controls. Selective in vivo radiolabeling of plasma NTBI with (59)Fe revealed similar results. Expression of exogenous PrP(C) in immortalized PT cells showed localization on the plasma membrane and intracellular vesicles and increased transepithelial transport of (59)Fe-NTBI and to a smaller extent (59)Fe-Tf from the apical to the basolateral domain. Notably, the ferrireductase-deficient mutant of PrP (PrP(Δ51-89)) lacked this activity. Furthermore, excess NTBI and hemin caused aggregation of PrP(C) to a detergent-insoluble form, limiting iron uptake. Together, these observations suggest that PrP(C) promotes retrieval of iron from the glomerular filtrate via its ferrireductase activity and modulates kidney iron metabolism.

A review of luteinising hormone and human chorionic gonadotropin when used in assisted reproductive technology

Gonadotropins extracted from the urine of post-menopausal women have traditionally been used to stimulate folliculogenesis in the treatment of infertility and in assisted reproductive technology (ART). Products, such as human menopausal gonadotropin (hMG), consist not only of a mixture of the hormones, follicle-stimulating hormone (FSH), luteinising hormone (LH) and human chorionic gonadotropin (hCG), but also other biologically active contaminants, such as growth factors, binding proteins and prion proteins. The actual amount of molecular LH in hMG preparations varies considerably due to the purification process, thus hCG, mimicking LH action, is added to standardise the product. However, unlike LH, hCG plays a different role during the natural human menstrual cycle. It is secreted by the embryo and placenta, and its main role is to support implantation and pregnancy. More recently, recombinant gonadotropins (r-hFSH and r-hLH) have become available for ART therapies. Recombinant LH contains only LH molecules. In the field of reproduction there has been controversy in recent years over whether r-hLH or hCG should be used for ART. This review examines the existing evidence for molecular and functional differences between LH and hCG and assesses the clinical implications of hCG-supplemented urinary therapy compared with recombinant therapies used for ART.

Searching for reliable premortem protein biomarkers for prion diseases: progress and challenges to date

Prion diseases are a unique family of fatal neurodegenerative diseases caused by abnormal folding of normal cellular prion proteins in the brain. Due to the high risk of prion disease transmission and the lack of effective treatment to cure or delay the disease progression, prion diseases pose a serious threat to public health. To control and prevent prion diseases, an early diagnosis is urgently needed. Proteomic analysis has emerged as a powerful technology to decipher biological and pathophysiological processes and identify protein biomarkers indicative of disease. In this article, the authors review the use of the latest proteomic technologies for the identification of promising prion disease biomarkers, the challenges that exist in biomarker development pipelines and the new directions for utilizing proteomics for future biomarker discovery in the context of prion disease diagnostics.

The redox state of recombinant human serum albumin and its optimal concentration for mouse embryo culture

Albumin has multiple physiological functions in embryo culture, such as a chelator of heavy metals, free radical scavenger, pH and osmotic regulator, a stabilizer, growth factor carrier, a surfactant, and a nutrient. However, the commercially available human serum albumin (HSA) products may not be completely safe since they could be contaminated with viruses and prions. Recombinant human serum albumin (rHSA) has been reported to be as efficient as commercial HSA for fertilization and embryo development. Despite the possible benefits of rHSA, it has not been widely used for embryo culture due to its high cost of production. Our objective was to analyze the redox state of different types of HSA products and rHSA to define oxidative status batch variations of HSA and rHSA and to evaluate the optimal concentration of rHSA for mouse embryo culture. The redox state of the HSA and rHSA used in embryo culture media was found to vary widely. Redox variations were found among different HSA batches as well as among rHSA batches. The highest blastocyst development and hatching rates were obtained with rHSA used at a concentration of 0.05 mg/mL. We showed that very low concentrations of rHSA were most favorable for advanced mouse embryo development in culture.

Iatrogenic prion diseases in humans: an update

Although Creutzfeldt-Jakob disease (CJD) was first identified in 1920, prevention of transmission raised particular concern all over the world when a new variant of the disease was first described in 1996. There is good evidence of iatrogenic transmission of this new variant among human beings through blood, blood components, tissues and growth hormone. Furthermore, four cases of iatrogenic transmission of CJD through fertility treatment with human pituitary-derived gonadotrophins have been reported. It is important to distinguish the categories of infectivity and categories of risk, which require consideration not only of the level of infectivity of a given tissue or fluid, but also the amount of tissue/fluid to which a person is exposed, the duration of exposure and the route by which infection is transmitted. The potential presence and infectivity of prion proteins in human urinary gonadotrophin preparations is a matter of debate. Differences in the sensitivity of bioassay methods are of paramount importance when considering the infectivity of a tissue. Some new methods might detect small amounts of agent in some tissues currently thought to be free of infectivity. No cases of human prion disease due to the use of urinary gonadotrophins have been recognized to date. However, the detection of prions in the urine of experimental animals and in some urine-based preparations, and the young age of fertility drug recipients, require the application of the precautionary principle to urinary preparations.

Mass Spectrometry-based Proteomics and Peptidomics for Systems Biology and Biomarker Discovery

The scientific community has shown great interest in the field of mass spectrometry-based proteomics and peptidomics for its applications in biology. Proteomics technologies have evolved to produce large datasets of proteins or peptides involved in various biological and disease progression processes producing testable hypothesis for complex biological questions. This review provides an introduction and insight to relevant topics in proteomics and peptidomics including biological material selection, sample preparation, separation techniques, peptide fragmentation, post-translation modifications, quantification, bioinformatics, and biomarker discovery and validation. In addition, current literature and remaining challenges and emerging technologies for proteomics and peptidomics are presented.

Assessing prion infectivity of human urine in sporadic Creutzfeldt-Jakob disease

Prion diseases are neurodegenerative conditions associated with a misfolded and infectious protein, scrapie prion protein (PrP(Sc)). PrP(Sc) propagate prion diseases within and between species and thus pose risks to public health. Prion infectivity or PrP(Sc) presence has been demonstrated in urine of experimentally infected animals, but there are no recent studies of urine from patients with Creutzfeldt-Jakob disease (CJD). We performed bioassays in transgenic mice expressing human PrP to assess prion infectivity in urine from patients affected by a common subtype of sporadic CJD, sCJDMM1. We tested raw urine and 100-fold concentrated and dialyzed urine and assessed the sensitivity of the bioassay along with the effect of concentration and dialysis on prion infectivity. Intracerebral inoculation of transgenic mice with urine from 3 sCJDMM1 patients failed to demonstrate prion disease transmission, indicating that prion infectivity in urine from sCJDMM1 patients is either not present or is <0.38 infectious units/mL.

Ovarian stimulation protocols in assisted reproductive technology: an update

Controlled ovarian stimulation (COS) with gonadotropins to produce multiple follicular development and high-quality oocytes is the cornerstone of assisted reproductive technology. Today, recombinant human follicle-stimulating hormone (r-hFSH) is widely used for COS. A long-acting r-hFSH and a combination of r-hFSH and recombinant human luteinizing hormone have recently become available. Formulations of purified urinary FSH with or without luteinizing hormone activity (provided by human chorionic gonadotropin) are also available. COS protocols can now be individualized to optimize efficacy and safety - defined as singleton pregnancies with a low incidence of ovarian hyperstimulation syndrome. This is facilitated by an estimation of ovarian response using the antral follicle count and/or serum anti-Müllerian hormone levels; anti-Müllerian hormone is viewed as the most reliable single marker. However, an efficient management strategy for poor responders to COS is still required. Developments in biomarkers and other techniques for accurate identification of viable oocytes and embryos and optimal uterine receptivity are expected.

Gonadotropin stimulation: past, present and future

Gonadotropin therapy is so central to infertility treatment that it is easy to overlook the considerable discovery and research that preceded production of the effective and safe products available today. The history underpinning this development spans over 300 years and provides a splendid example of how basic animal experimentation and technological advances have progressed to clinical application. Following the discovery of germ cells in 1677 and realizing, in 1870, that fertilization involved the merging of two cell nuclei, one from the egg and one from sperm, it took another 40 years to discover the interplay between hypothalamus, pituitary and gonads. The potential roles of gonadotropin regulation were discovered in 1927. Gonadotropin, such as pregnant mare serum gonadotropin (PMSG), was first introduced for ovarian stimulation in 1930. However, use of PMSG leads to antibody formation, and had to be withdrawn. Following withdrawal of PMSG, human pituitary gonadotropin (HPG) and urinary menopausal gonadotropin (hMG) appeared on the market, and 50 years ago the first child was delivered by our group in 1961 and opened the path to controlled ovarian stimulation. HPG produced good results, but its use came to an end in the late 1980s when it was linked to the development of Creutzfeldt-Jakob disease (CJD). HMG preparations containing a high percentage of unknown urinary proteins, making quality control almost impossible, were then the only gonadotropins remaining on the market. With the availability of hMG, clomiphene citrate, ergot derivatives, GnRH agonists and antagonists, as well as metformin, algorithms were developed for their optimal utilization and were used for the next four decades. Following the first human IVF baby in 1978 and ICSI in 1991, such procedures became standard practice. The main agents for controlled ovarian stimulation for IVF were gonadotropins and GnRH analogues, with batch to batch consistent gonadotropic preparations; methods could be developed to predict and select the correct dose and the optimal protocol for each patient. We are now seeing the appearance of gonadotropin with sustained action and orally active GnRH analogues as well as orally active molecules capable to stimulate follicle growth and inducing ovulation. These new developments may one day remove the need for the classical gonadotropin in clinical work.