3D Printed Microfluidic Devices for Microchip Electrophoresis of Preterm Birth Biomarkers

This work demonstrates for the first time the creation of microchip electrophoresis devices with ∼50 μm cross-sectional dimensions by stereolithographic 3D printing and their application in the analysis of medically significant biomarkers related to risk for preterm birth (PTB). We determined that device current was linear with applied potential up to 800 V (620 V/cm). We optimized device and separation conditions using fluorescently labeled amino acids as a model system and compared the performance in our 3D printed microfluidic devices to that in other device materials commonly used for microchip electrophoresis analysis. We demonstrated for the first time microchip electrophoresis in a 3D printed device of three PTB biomarkers, including peptides and a protein, with suitable separation characteristics. Limits of detection for microchip electrophoresis in 3D printed microfluidic devices were also determined for PTB biomarkers to be in the high picomolar to low nanomolar range.

Applying mass spectrometric methods to study androgen biosynthesis and metabolism in prostate cancer

Recent development of gas chromatography and liquid chromatography-tandem mass spectrometry (GC-MS/MS, LC-MS/MS) has provided novel tools to define sex steroid concentrations. These new methods overcome several of the problems associated with immunoassays for sex steroids. With the novel MS-based applications we are now able to measure small concentrations of the steroid hormones reliably and with high accuracy in both body fluids and tissue homogenates. The sensitivity of the tandem mass spectrometry assays allows us also for the first time to reliably measure picomolar or even femtomolar concentrations of estrogens and androgens. Furthermore, due to a high sensitivity and specificity of MS technology, we are also able to measure low concentrations of steroid hormones of interest in the presence of pharmacological concentration of other steroids and structurally closely related compounds. Both of these features are essential for multiple preclinical models for prostate cancer. The MS assays are also valuable for the simultaneous measurement of multiple steroids and their metabolites in small sample volumes in serum and tissue biopsies of prostate cancer patients before and after drug interventions. As a result, novel information about steroid hormone synthesis and metabolic pathways in prostate cancer has been obtained. In our recent studies, we have extensively applied a GC-MS/MS method to study androgen biosynthesis and metabolism in VCaP prostate cancer xenografts in mice. In the present review, we shortly summarize some of the benefits of the GC-MS/MS and novel LC-MS/MS assays, and provide examples of their use in defining novel mechanisms of androgen action in prostate cancer.

Evaluation of Saliva as a Potential Alternative Sampling Matrix for Therapeutic Drug Monitoring of Levofloxacin in Patients with Multidrug-Resistant Tuberculosis

Saliva may be a useful alternative matrix for monitoring levofloxacin concentrations in multidrug-resistant tuberculosis (MDR-TB) patients. The objectives of this study were (i) to evaluate the correlation between plasma and salivary levofloxacin (Lfx) concentrations in MDR-TB patients and (ii) to gauge the possibility of using saliva as an alternative sampling matrix for therapeutic drug monitoring of Lfx in areas where TB is endemic. This was a prospective pharmacokinetic study that enrolled MDR-TB patients receiving levofloxacin (750- to 1,000-mg once-daily dosing) under standardized treatment regimen in Nepal. Paired blood and saliva samples were collected at steady state. Lfx concentrations were quantified using liquid chromatography-tandem mass spectrometry. Pharmacokinetic parameters were calculated using noncompartmental kinetics. Lfx drug exposures were evaluated in 23 MDR-TB patients. During the first month, the median (interquartile range [IQR]) areas under the concentration-time curve from 0 to 24 h (AUC_0-24) were 67.09 (53.93 to 98.37) mg ⋅ h/liter in saliva and 99.91 (76.80 to 129.70) mg ⋅ h/liter in plasma, and the saliva plasma (S/P) ratio was 0.69 (0.53 to 0.99). Similarly, during the second month, the median (IQR) AUC_0-24 were 75.63 (61.45 to 125.5) mg ⋅ h/liter in saliva and 102.7 (84.46 to 131.9) mg ⋅ h/liter in plasma, with an S/P ratio of 0.73 (0.66 to 1.18). Furthermore, large inter- and intraindividual variabilities in Lfx concentrations were observed. This study could not demonstrate a strong correlation between plasma and saliva Lfx levels. Despite a good Lfx penetration in saliva, the variability in individual saliva-to-plasma ratios limits the use of saliva as a valid substitute for plasma. Nevertheless, saliva could be useful in semiquantitatively predicting Lfx plasma levels. (This study has been registered at ClinicalTrials.gov under identifier NCT03000517.).

The immune system of the freshwater zebra mussel, Dreissena polymorpha, decrypted by proteogenomics of hemocytes and plasma compartments

The immune system of bivalves is of great interest since it reflects the health status of these organisms during stressful conditions. While immune molecular responses are well documented for marine bivalves, few information is available for continental bivalves such as the zebra mussel, Dreissena polymorpha. A proteogenomic approach was conducted on both hemocytes and plasma to identified immune proteins of this non-model species. Combining transcriptomic sequences with mass spectrometry data acquired on proteins is a relevant strategy since 3020 proteins were identified, representing the largest protein inventory for this sentinel organism. Functional annotation and gene ontology (GO) analysis performed on the identified proteins described the main molecular players of hemocytes and plasma in immunity. GO analysis highlights the complementary immune functions of these two compartments in the management of micro-organisms. Functional annotation revealed new mechanisms in the immune defence of the zebra mussel. Proteins rarely observed in the hemolymph of bivalves were pinpointed such as natterin-like and thaumatin-like proteins. Furthermore, the high abundance of complement-related proteins observed in plasma suggested a strong implication of the complement system in the immune defence of D. polymorpha. This work brings a better understanding of the molecular mechanisms involved in zebra mussel immunity. SIGNIFICANCE: Although the molecular mechanisms of marine bivalves are widely investigated, little information is known for continental bivalves. Moreover, few proteomic studies described the complementarity of both hemolymphatic compartments (cellular and plasmatic) in the immune defence of invertebrates. The recent proteogenomics concept made it possible to discover proteins in non-model organisms. Here, we propose a proteogenomic strategy with the zebra mussel, a key sentinel species for biomonitoring of freshwater, to identify and describe the molecular actors involved in the immune system in both hemocytes and plasma compartments. More widely, this study provided new insight into bivalve immunity.

Reliable LC-MS Multiattribute Method for Biotherapeutics by Run-Time Response Calibration

A major challenge of a mass-spectrometry-based quantitative multiattribute method (MAM) for biotherapeutics is its high variability between instruments. For reproducible attribute measurements, not only is a similar instrument model required, but the instruments must also be tuned to the same condition. This poses great long-term challenges, considering the rapid development of new instrumentations. In addition, differences in digestion efficiency, peptide recovery, and artificial modifications during sample preparation also contribute to variability between laboratories. To overcome these challenges, new mathematical methods are developed to calculate the attribute abundance in the sample, using the reference standard (RS) material as calibrant. Most quality attributes in the RS remain constant throughout the life of the standard, and therefore, the RS can serve as a calibrant to correct for the difference between instruments or sample preparation procedures. Because RS data are usually collected in a MAM assay, no additional work is required from the analyst. Data from a large number of attributes demonstrated that these methodologies greatly reduced instrument-to-instrument and sample preparation variabilities. With these methodologies, a consistent instrument model and sample preparation procedure is no longer a requirement. As a result, changes in digestion procedure and advances in instrumentations will not significantly affect the assay result.

Clinical application of a dried blood spot assay for sirolimus and everolimus in transplant patients

Background

Monitoring of immunosuppressive drugs such as everolimus and sirolimus is important in allograft rejection prevention in transplant patients. Dried blood spots (DBS) sampling gives patients the opportunity to sample a drop of blood from a fingerprick at home, which can be sent to the laboratory by mail.

Methods

A total of 39 sirolimus and 44 everolimus paired fingerprick DBS and whole blood (WB) samples were obtained from 60 adult transplant patients for method comparison using Passing-Bablok regression. Bias was assessed using Bland-Altman. Two validation limits were pre-defined: limits of analytical acceptance were set at >67% of all paired samples within 20% of the mean of both samples and limits of clinical relevance were set in a multidisciplinary team at >80% of all paired samples within 15% of the mean of both samples.

Results

For both sirolimus and everolimus, Passing-Bablok regression showed no differences between WB and DBS with slopes of 0.86 (95% CI slope, 0.72–1.02) and 0.96 (95% CI 0.84–1.06), respectively. Only everolimus showed a significant constant bias of 4%. For both sirolimus and everolimus, limits of analytical acceptance were met (76.9% and 81.8%, respectively), but limits or clinical relevance were not met (77.3% and 61.5%, respectively).

Conclusions

Because pre-defined limits of clinical relevance were not met, this DBS sampling method for sirolimus and everolimus cannot replace WB sampling in our center at this time. However, if the clinical setting is compatible with less strict limits for clinical relevance, this DBS method is suitable for clinical application.

AFFINImeter: A software to analyze molecular recognition processes from experimental data

The comprehension of molecular recognition phenomena demands the understanding of the energetic and kinetic processes involved. General equations valid for the thermodynamic analysis of any observable that is assessed as a function of the concentration of the involved compounds are described, together with their implementation in the AFFINImeter software. Here, a maximum of three different molecular species that can interact with each other to form an enormous variety of supramolecular complexes are considered. The corrections currently employed to take into account the effects of dilution, volume displacement, concentration errors and those due to external factors, especially in the case of ITC measurements, are included. The methods used to fit the model parameters to the experimental data, and to generate the uncertainties are described in detail. A simulation tool and the so called kinITC analysis to get kinetic information from calorimetric experiments are also presented. An example of how to take advantage of the AFFINImeter software for the global multi-temperature analysis of a system exhibiting cooperative 1:2 interactions is presented and the results are compared with data previously published. Some useful recommendations for the analysis of experiments aimed at studying molecular interactions are provided.

Darunavir Population Pharmacokinetic Model Based on HIV Outpatient Data

Supplemental Digital Content is Available in the Text.

Background:

Darunavir is a second-generation protease inhibitor and is registered for the treatment of HIV-1 infection. The aim of this study was to develop and validate a darunavir population pharmacokinetic model based on data from daily practice.

Methods:

Data sets were obtained from 2 hospitals: ASST Fatebenefratelli Sacco University Hospital, Italy (hospital A), and University Medical Center Groningen, the Netherlands (hospital B). A pharmacokinetic model was developed using data from the largest data set using the iterative two-stage Bayesian procedure within the MWPharm software package. External validation was conducted using data from the smaller data set with Passing–Bablok regression and Bland–Altman analyses.

Results:

In total, data from 198 patients from hospital A and 170 patients from hospital B were eligible for inclusion. A 1-compartment model with first-order absorption and elimination resulted in the best model. The Passing–Bablok analysis demonstrated a linear correlation between measured concentration and predicted concentration with r² = 0.97 (P < 0.05). The predicted values correlated well with the measured values as determined by a Bland–Altman analysis and were overestimated by a mean value of 0.12 mg/L (range 0.23–0.94 mg/L). A total of 98.2% of the predicted values were within the limits of agreement.

Conclusions:

A robust population pharmacokinetic model was developed, which can support therapeutic drug monitoring of darunavir in daily outpatient settings.

Cooperative energetic effects elicited by the yeast Shwachman-Diamond syndrome protein (Sdo1) and guanine nucleotides modulate the complex conformational landscape of the elongation factor-like 1 (Efl1) GTPase

One of the final maturation steps of the large ribosomal subunit requires the joint action of the elongation factor-like 1 (human EFL1, yeast Efl1) GTPase and the Shwachman-Diamond syndrome protein (human SBDS, yeast Sdo1) to release the eukaryotic translation initiation factor 6 (human eIF6, yeast Tif6) and allow the assembly of mature ribosomes. EFL1 function is driven by conformational changes. However, the nature of such conformational changes or the mechanism by which they are prompted are still largely unknown. In previous studies, it has been established that this GTPase interacts with its cofactor in solution in an inverted orientation with respect to the binding mode derived from 60S ribosome subunit cryo-EM data. To shed new light on this conundrum, we characterized calorimetrically the energetic basis describing the recognition of Efl1 to GT(D)P, Sdo1 and their intercommunication in solution. A structural-based analysis of the binding signatures indicates that Efl1 has a large structural flexibility. The mutual effects of Sdo1 and nucleotides on Efl1 modulate in a very specific and robust way the complex conformational landscape of Efl1, resembling the behavior observed with other GTPases and their cofactors.

In-Transit Electroextraction of Small-Molecule Pharmaceuticals from Blood

An electrokinetic platform was developed for extracting small-molecule pharmaceuticals from a dried blood spot. Through the exclusion of liquid reagents and use of low field strength (6 V cm^-1 ), the electroextraction of a drug from a dried blood spot, deposited on a polymer inclusion membrane (PIM), could be realised while in transit in the mail. In transit sample preparation provides a potential solution to in situ sample degradation and may accelerate the workflow upon arrival of a patient sample at the analytical facility. The electroextraction method was enabled through our discovery of the use of 15-20 μm thin PIMs as electrophoretic separation medium in absence of liquid reagents. Here, a PIM consisting of cellulose triacetate as polymer base, 2-nitrophenyl octyl ether as plasticizer and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide as carrier was used. The PIM, was packaged with two 12 V batteries to supply the separation voltage. A blood spot containing berberine chloride was deposited and dried before the applying the separation potential, allowing for the electroextraction while the packaged device was shipped in internal mail. Upon arrival in the analytical laboratory, the PIM was analysed using a fluorescence microscope with photon multiplier tube, quantifying the berberine extracted away from the sample matrix. This platform represents a new opportunity for processing clinical samples during transport to the laboratory, saving time and manual handling to accelerate the time to result.

Ultrasensitive chemiluminescence assay for cimetidine detection based on the synergistic improving effect of Au nanoclusters and graphene quantum dots

A novel and sensitive chemiluminescence (CL) procedure based on the synergetic catalytic effects of gold nanoclusters (Au NCs) and graphene quantum dots (GQDs) was developed for the reliable measurement of cimetidine (CM). The initial experiments showed that the KMnO₄ -based oxidation of alkaline rhodamine B (RhoB) generated a very weak CL emission, which was intensively enhanced in the simultaneous presence of Au NCs and GQDs. CL intermediates can be adsorbed and gathered on the surface of Au NCs, becoming more stable. GQDs participate in the energy transferring processes and facilitate them. These improving effects were simultaneously obtained by adding both Au NCs and GQDs into the RhoB-KMnO₄ reaction. Consequently, the increasing effect of the Au NCs/GQDs mixture was more than that of pure Au NCs or GQDs, and a new nano-assisted powerful CL system was achieved. Furthermore, a marked quenching in the emission of the introduced CL system was observed in the presence of CM, so the system was examined to design a sensitive sensor for CM. After optimization of influencing parameters, the linear lessening in CL emission intensity of KMnO₄ -RhoB-Au NCs/GQDs was verified for CM concentrations in the range 0.8-200 ng ml^-1 . The limit of detection (3S_b /m) was 0.3 ng ml^-1 . Despite being a simple CL method, good sensitivity was obtained for CM detection with reliable results for CM determination in human urine samples.

The Incorporation of Host Proteins into the External HIV-1 Envelope

The incorporation of biologically active host proteins into HIV-1 is a well-established phenomenon, particularly due to the budding mechanism of viral egress in which viruses acquire their external lipid membrane directly from the host cell. While this mechanism might seemingly imply that host protein incorporation is a passive uptake of all cellular antigens associated with the plasma membrane at the site of budding, this is not the case. Herein, we review the evidence indicating that host protein incorporation can be a selective and conserved process. We discuss how HIV-1 virions displaying host proteins on their surface can exhibit a myriad of altered phenotypes, with notable impacts on infectivity, homing, neutralization, and pathogenesis. This review describes the canonical and emerging methods to detect host protein incorporation, highlights the well-established host proteins that have been identified on HIV-1 virions, and reflects on the role of these incorporated proteins in viral pathogenesis and therapeutic targeting. Despite many advances in HIV treatment and prevention, there remains a global effort to develop increasingly effective anti-HIV therapies. Given the broad range of biologically active host proteins acquired on the surface of HIV-1, additional studies on the mechanisms and impacts of these incorporated host proteins may inform the development of novel treatments and vaccine designs.

Multiplex LC-MS/MS Assays for Clinical Bioanalysis of MEDI4276, an Antibody-Drug Conjugate of Tubulysin Analogue Attached via Cleavable Linker to a Biparatopic Humanized Antibody against HER-2

Bioanalysis of complex biotherapeutics, such as antibody-drug conjugates (ADCs), is challenging and requires multiple assays to describe their pharmacokinetic (PK) profiles. To enable exposure-safety and exposure-efficacy analyses, as well as to understand the metabolism of ADC therapeutics, three bioanalytical methods are typically employed: Total Antibody, Antibody Conjugated Toxin or Total ADC and Unconjugated Toxin. MEDI4276 is an ADC comprised of biparatopic humanized antibody attached via a protease-cleavable peptide-based maleimidocaproyl linker to a tubulysin toxin (AZ13599185) with an approximate average drug-antibody ratio of 4. The conjugated payload of MEDI4276 can undergo ester hydrolysis to produce the conjugated payload AZ13687308, leading to the formation of MEDI1498 (de-acetylated MEDI4276). In this report, we describe the development, validation and application of three novel multiplex bioanalytical methods. The first ligand-binding liquid chromatography coupled with tandem mass spectrometry (LBA-LC-MS/MS) method was developed and validated for simultaneous measurement of total antibody and total ADC (antibody-conjugated AZ13599185) from MEDI4276. The second LBA-LC-MS/MS assay quantified total ADC (antibody-conjugated AZ13687308) from MEDI1498. The third multiplex LC-MS/MS assay was used for simultaneous quantification of unconjugated AZ13599185 and AZ13687308. Additional stability experiments confirmed that quantification of the released warhead in the presence of high concentrations of MEDI4276 was acceptable. Subsequently, the assays were employed in support of a first-in-human clinical trial (NCT02576548).

Anion-specific interaction with human NQO1 inhibits flavin binding

Ion binding to biomacromolecules can modulate their activity and stability in vivo. It is of particular interest to understand the structural and energetic basis of anion binding to functional sites of biomacromolecules. In this work, binding of anions to the FAD binding pocket of human NAD(P)H:quinone oxidoreductase 1 (NQO1), a flavoprotein associated with cancer due to a common polymorphism causing a P187S amino acid substitution, was investigated. It is known that NQO1 stability in vivo is strongly modulated by binding of its flavin cofactor. Herein, binding and protein stability analyses were carried out to show that anion binding to the apo-state of NQO1 P187S inhibits FAD binding with increasing strength following the chaotropic behavior of anions. These inhibitory effects were significant for some anions even at low millimolar concentrations. Additional pH dependent analyses suggested that protonation of histidine residues in the FAD binding pocket was not critical for anion or flavin binding. Overall, this detailed biophysical analysis helps to understanding how anions modulate NQO1 functionality in vitro, thus allowing hypothesize that NQO1 stability in vivo could be modulated by differential anion binding and subsequent inhibition of FAD binding.

Effect of efavirenz-based antiretroviral therapy and high-dose rifampicin on the pharmacokinetics of isoniazid and acetyl-isoniazid

Objectives

To describe the pharmacokinetics of isoniazid and acetyl-isoniazid in TB/HIV-coinfected patients, and assess the effects of efavirenz co-administration and a 50% increase in the dose of rifampicin on the pharmacokinetic parameters of isoniazid and acetyl-isoniazid.

Methods

TB/HIV-coinfected patients participating in the three-treatment-arm RAFA randomized controlled trial conducted in West Africa were recruited into the pharmacokinetics sub-study. Five serial blood samples were collected on a single visit between 4 and 8 weeks after initiation of antituberculosis treatment. Concentration-time data for isoniazid and acetyl-isoniazid were analysed using non-linear mixed-effects models.

Results

Isoniazid concentrations from 150 patients were available for analysis, and 79 of these (53%) also had concentrations of acetyl-isoniazid. Isoniazid pharmacokinetics was best described with a two-compartment disposition model with lagged first-order absorption and elimination using a semi-mechanistic model describing hepatic extraction. The model identified two elimination pathways, separating formation of acetyl-isoniazid from other routes of metabolism. The predicted AUC0-24 is reduced by 29% in patients who are fast acetylators of isoniazid and receiving efavirenz-based ART (6.73 versus 4.68 mg·h/L). In slow acetylators, efavirenz-based ART had no effect on isoniazid exposure (AUC0-24 = 17.5 mg·h/L).

Conclusions

Efavirenz-based ART affects the acetylation metabolic pathway amongst rapid acetylators, resulting in reduced exposure to isoniazid. Pharmacokinetics of isoniazid and acetyl-isoniazid were not influenced by the 50% increase in rifampicin dose.

Flow-Induced Dispersion Analysis (FIDA) for Protein Quantification and Characterization

Flow-Induced Dispersion Analysis (FIDA) enables characterization and quantification of proteins under native conditions. FIDA is based on measuring the change in size of a ligand as it selectively interacts with the target protein. The unbound ligand has a relatively small apparent hydrodynamic radius (size), which increase in the presence of the analyte due to binding to the analyte. The K_d of the interaction may be obtained in a titration experiment and the measurement of the apparent ligand size in an unknown sample forms the basis for determining the analyte concentration. The apparent molecular size is measured by Taylor dispersion analysis (TDA) in fused silica capillary capillaries. FIDA is a "ligand-binding" assay and has therefore certain features in common with Enzyme-Linked Immunosorbent Assay (ELISA), Surface Plasmon Resonance (SPR), and Biolayer Interferometry (BLI) based techniques. However, FIDA probes a single in-solution binding event and thus makes assay development straightforward, and the absolute size measurement enables built-in assay quality control. Further, as FIDA does not involve surface chemistries, complications related to nonspecific adsorption of analyte and assay components are minimized enabling direct measurement in, e.g., plasma and serum.

Middle-down approach: a choice to sequence and characterize proteins/proteomes by mass spectrometry

Owing to rapid growth in the elucidation of genome sequences of various organisms, deducing proteome sequences has become imperative, in order to have an improved understanding of biological processes. Since the traditional Edman method was unsuitable for high-throughput sequencing and also for N-terminus modified proteins, mass spectrometry (MS) based methods, mainly based on soft ionization modes: electrospray ionization and matrix-assisted laser desorption/ionization, began to gain significance. MS based methods were adaptable for high-throughput studies and applicable for sequencing N-terminus blocked proteins/peptides too. Consequently, over the last decade a new discipline called 'proteomics' has emerged, which encompasses the attributes necessary for high-throughput identification of proteins. 'Proteomics' may also be regarded as an offshoot of the classic field, 'biochemistry'. Many protein sequencing and proteomic investigations were successfully accomplished through MS dependent sequence elucidation of 'short proteolytic peptides (typically: 7-20 amino acid residues), which is called the 'shotgun' or 'bottom-up (BU)' approach. While the BU approach continues as a workhorse for proteomics/protein sequencing, attempts to sequence intact proteins without proteolysis, called the 'top-down (TD)' approach started, due to ambiguities in the BU approach, e.g., protein inference problem, identification of proteoforms and the discovery of posttranslational modifications (PTMs). The high-throughput TD approach (TD proteomics) is yet in its infancy. Nevertheless, TD characterization of purified intact proteins has been useful for detecting PTMs. With the hope to overcome the pitfalls of BU and TD strategies, another concept called the 'middle-down (MD)' approach was put forward. Similar to BU, the MD approach also involves proteolysis, but in a restricted manner, to produce 'longer' proteolytic peptides than the ones usually obtained in BU studies, thereby providing better sequence coverage. In this regard, special proteases (OmpT, Sap9, IdeS) have been used, which can cleave proteins to produce longer proteolytic peptides. By reviewing ample evidences currently existing in the literature that is predominantly on PTM characterization of histones and antibodies, herein we highlight salient features of the MD approach. Consequently, we are inclined to claim that the MD concept might have widespread applications in future for various research areas, such as clinical, biopharmaceuticals (including PTM analysis) and even for general/routine characterization of proteins including therapeutic proteins, but not just limited to analysis of histones or antibodies.

Preanalytical considerations in therapeutic drug monitoring of immunosuppressants with dried blood spots

Background

Dried blood spots (DBSs) could allow patients to prepare their own samples at home and send them to the laboratory for therapeutic drug monitoring (TDM) of immunosuppressants. The purpose of this review is to provide an overview of the current knowledge about the impact of DBS-related preanalytical factors on TDM of tacrolimus, sirolimus and everolimus.

Content

Blood spot volume, blood spot inhomogeneity, stability of analytes in DBS and hematocrit (Hct) effects are considered important DBS-related preanalytical factors. In addition, the influence of drying time has recently been identified as a noteworthy preanalytical factor. Tacrolimus is not significantly influenced by these factors. Sirolimus and everolimus are more prone to heat degradation and exhibited variations in recovery which were dependent on Hct and drying time.

Summary and outlook

DBS-related preanalytical factors can have a significant impact on TDM for immunosuppressants. Tacrolimus is not significantly influenced by the studied preanalytical factors and is a viable candidate for DBS sampling. For sirolimus and everolimus more validation of preanalytical factors is needed. In particular, drying conditions need to be examined further, as current protocols may mask Hct-dependent effects on recovery. Further validation is also necessary for home-based self-sampling of immunosuppressants as the sampling quality is variable.

Development of bioanalytical HPLC method for simultaneous determination of the antialzhiemer, donepezil hydrochloride and the antidepressant, citalopram hydrobromide in raw materials, spiked human plasma and tablets dosage form

OBJECTIVES

A novel, fast and sensitive HPLC method has been developed for the simultaneous bioanalytical determination of Donepezil hydrochloride (DON) and Citalopram hydrobromide (CTP) in raw materials, spiked human plasma and tablets.

MATERIALS AND METHODS

Elution of both drugs was achieved with very good resolution using a RP-C18 chromatographic column, samples were analyzed using Hypersil Gold (100mm×4.6mm), 5μm particle size column and an isocratic binary mobile phase consists of phosphate buffer (0.05 M): acetonitrile (65:35). A Diode array detector at wavelength 232nm was used. Chromatographic separation was within a short run time (less than 7minutes) for both drugs.

RESULTS

Retention times for DON and CTP were 4.5 and 5.8min, respectively. Linear calibration curves were obtained for DON and CTP over the concentration ranges of 0.1-10 and 0.1-50μg/mL. The mean extraction recoveries from spiked plasma were 93.22 and 92.64 for DON and CTP, respectively. The limits of detection and quantification were 0.017, 0.035μg/mL and 0.052, 0.106μg/mL for DON and CTP, respectively.

CONCLUSION

The proposed method was successfully applied to the analysis of the cited drugs in raw materials, spiked human plasma and tablets with excellent accuracy and precision.

Proteomic analysis of protein homeostasis and aggregation

Protein homeostasis (proteostasis) refers to the ability of cells to preserve the correct balance between protein synthesis, folding and degradation. Proteostasis is essential for optimal cell growth and survival under stressful conditions. Various extracellular and intracellular stresses including heat shock, oxidative stress, proteasome malfunction, mutations and aging-related modifications can result in disturbed proteostasis manifested by enhanced misfolding and aggregation of proteins. To limit protein misfolding and aggregation cells have evolved various strategies including molecular chaperones, proteasome system and autophagy. Molecular chaperones assist folding of proteins, protect them from denaturation and facilitate renaturation of the misfolded polypeptides, whereas proteasomes and autophagosomes remove the irreversibly damaged proteins. The impairment of proteostasis results in protein aggregation that is a major pathological hallmark of numerous age-related disorders, such as cataract, Alzheimer's, Parkinson's, Huntington's, and prion diseases. To discover protein markers and speed up diagnosis of neurodegenerative diseases accompanied by protein aggregation, proteomic tools have increasingly been used in recent years. Systematic and exhaustive analysis of the changes that occur in the proteomes of affected tissues and biofluids in humans or in model organisms is one of the most promising approaches to reveal mechanisms underlying protein aggregation diseases, improve their diagnosis and develop therapeutic strategies. Significance: In this review we outline the elements responsible for maintaining cellular proteostasis and present the overview of proteomic studies focused on protein-aggregation diseases. These studies provide insights into the mechanisms responsible for age-related disorders and reveal new potential biomarkers for Alzheimer's, Parkinson's, Huntigton's and prion diseases.

In Vivo Stability Profiles of Anti-factor D Molecules Support Long-Acting Delivery Approaches

The collection of aqueous humor (phase 1 b/2 Mahalo study) from patients dosed intravitreally with anti-factor D (AFD; FCFD4514S, lampalizumab), a humanized antibody fragment previously under investigation to treat geographic atrophy (GA) secondary to age-related macular degeneration, presented a unique opportunity to examine AFD properties in clinical samples. We investigated AFD stability and target-binding characteristics to set up strategies for engineering and evaluating optimized molecules that enable less frequent dosing. Two variants, AFD.v8 and AFD.v14, were evaluated as alternatives to AFD for longer-acting treatments. Mass spectrometry, surface plasmon resonance, and immunoassay were used to assess AFD stability and binding activity in aqueous humor samples from Mahalo patients. In vitro stability and binding activity of AFD, AFD.v8, and AFD.v14 were assessed in human vitreous humor versus buffer at 37 °C over 16 weeks and in vivo in rabbits over 28 days along with pharmacokinetic determinations. In human aqueous humor, AFD specific binding was >85% through 30 days, and deamidation was <3% through 60 days, consistent with the AFD stability and binding activity in vitreous humor from humans in vitro and rabbits in vivo. Target binding, stability, and rabbit pharmacokinetic parameters of AFD.v8 and AFD.v14 were similar to those of AFD. Physiological stability and activity of AFD translated across in vitro and in vivo studies in humans and rabbits. The two variants AFD.v8 and AFD.v14 demonstrated comparable potency and pharmacokinetics. These findings, along with previously demonstrated improved solubility of AFD.v8 and AFD.v14, provide proof-of-concept for developing other similar long-acting therapeutic variants.

Evaluation of the Mitra microsampling device for use with key urinary metabolites in patients with Alkaptonuria

Aim: Alkaptonuria is a disorder of tyrosine metabolism where elevated circulating homogentisic acid causes progressive dysfunction of collagenous tissues. Logistical, financial and patient experience concerns with collection and transport of specimens to central laboratories makes evaluation of microsampling attractive. Methodology: Volumetric absorptive microsampling devices were evaluated for accuracy, precision and drying time. Elution methods were evaluated for several urinary metabolites of interest and stability assessed under multiple conditions. Comparison was performed between dried and liquid specimens via LC–MS/MS. Conclusion: Volumetric absorptive microsampling was found to be highly accurate and precise. Elution methods showed good recovery and reproducibility. Dried and liquid samples compared favorably. Analyte stability was variable, presenting barriers to implementation into routine use in this context.

2018 White Paper on Recent Issues in Bioanalysis: focus on immunogenicity assays by hybrid LBA/LCMS and regulatory feedback (Part 2 - PK, PD & ADA assays by hybrid LBA/LCMS & regulatory agencies' inputs on bioanalysis, biomarkers and immunogenicity)

The 2018 12^th Workshop on Recent Issues in Bioanalysis took place in Philadelphia, PA, USA on April 9-13, 2018 with an attendance of over 900 representatives from pharmaceutical/biopharmaceutical companies, biotechnology companies, contract research organizations and regulatory agencies worldwide. WRIB was once again a 5-day, week-long event - a full immersion week of bioanalysis, biomarkers and immunogenicity. As usual, it was specifically designed to facilitate sharing, reviewing, discussing and agreeing on approaches to address the most current issues of interest including both small- and large-molecule bioanalysis involving LCMS, hybrid LBA/LCMS and LBA/cell-based assays approaches. This 2018 White Paper encompasses recommendations emerging from the extensive discussions held during the workshop and is aimed to provide the bioanalytical community with key information and practical solutions on topics and issues addressed, in an effort to enable advances in scientific excellence, improved quality and better regulatory compliance. Due to its length, the 2018 edition of this comprehensive White Paper has been divided into three parts for editorial reasons. This publication (Part 2) covers the recommendations for PK, PD and ADA assays by hybrid LBA/LCMS and regulatory agencies' input. Part 1 (LCMS for small molecules, peptides, oligonucleotides and small molecule biomarkers) and Part 3 (LBA/cell-based assays: immunogenicity, biomarkers and PK assays) are published in volume 10 of Bioanalysis, issues 22 and 24 (2018), respectively.

Perspectives on potentiating immunocapture-LC-MS for the bioanalysis of biotherapeutics and biomarkers

The integration of ligand-binding assay and LC-MS/MS (immunocapture-LC-MS) has unleashed the combined advantages of both powerful techniques for addressing the ever increasing bioanalytical challenges for biotherapeutics and biomarker assays. The highly specific, selective and sensitive characteristics of the immunocapture-LC-MS-based assays have enabled the determination of biotherapeutics and biomarkers in biomatrices with ease of method development, less requirements on key reagents as well as structural specificity for endogenous and engineered biomolecules. In addition, the versatile immunocapture-LC-MS technology has expanded into many challenging areas to enhance mechanistic studies of drug interactions with their targets. This paper intends to summarize our perspectives on enhancing the use of immunocapture-LC-MS in drug discovery and development for emerging new modalities.

Optimisation of Milk Protein Top-Down Sequencing Using In-Source Collision-Induced Dissociation in the Maxis Quadrupole Time-of-Flight Mass Spectrometer

Top-down sequencing in proteomics has come of age owing to continuous progress in LC-MS. With their high resolution and broad mass range, Quadrupole Time-of-Flight (Q-ToF) hybrid mass spectrometers equipped with electrospray ionisation source and tandem MS capability by collision-induced dissociation (CID) can be employed to analyse intact proteins and retrieve primary sequence information. To our knowledge, top-down proteomics methods with Q-ToF have only been evaluated using samples of relatively low complexity. Furthermore, the in-source CID (IS-CID) capability of Q-ToF instruments has been under-utilised. This study aimed at optimising top-down sequencing of intact milk proteins to achieve the greatest sequence coverage possible from samples of increasing complexity, assessed using nine known proteins. Eleven MS/MS methods varying in their IS-CID and conventional CID parameters were tested on individual and mixed protein standards as well as raw milk samples. Top-down sequencing results from the nine most abundant proteoforms of caseins, alpha-lactalbumin and beta-lactoglubulins were compared. Nine MS/MS methods achieved more than 70% sequence coverage overall to distinguish between allelic proteoforms, varying only by one or two amino acids. The optimal methods utilised IS-CID at low energy. This experiment demonstrates the utility of Q-ToF systems for top-down proteomics and that IS-CID could be more frequently employed.

Isothermal titration calorimetry for characterization of recombinant proteins

Isothermal titration calorimetry is widely used to measure the affinities and enthalpies of interaction between proteins and/or small molecules. The quantitative nature of the technique is especially useful in the characterization of recombinant proteins while determining the fraction of protein capable of binding a specific ligand and thus the protein purity. The revealed thermodynamic information sheds light on the binding mechanism, important for the targeted drug design of the biologics. Here we show examples how, together with the thermal shift assay, combination of both techniques enables characterization of protein stability and ligand binding. Furthermore, the binding-linked reactions that strongly affect the observed thermodynamic parameters and must be dissected to obtain the intrinsic parameters that are necessary for the structure-based rational drug design are being demonstrated using inhibitors of Hsp90, an anticancer target protein.

Development of an ELISA–LC–MS hybrid assay for quantification of biotherapeutics

Background: Magnetic bead immunocapture-LC–MS has been widely used for bioanalysis of biotherapeutic proteins. However, magnetic beads are difficult to be fully automated and more costly than ELISA plates. Aim: Develop an ELISA–LC–MS hybrid assay as an alternate platform. Results: Among seven ELISA plates tested, Pierce streptavidin plates, which did not require time-consuming capture antibody precoating steps, provided the best sensitivity and assay dynamic range (5–2500 ng/ml or 10–5000 ng/ml), similar to magnetic bead immunocapture–LC–MS assay and better than an ELISA (50–500 ng/ml). The entire procedures could be fully automated using a liquid handling system. Conclusion: This study demonstrates that ELISA–LC–MS hybrid approach using streptavidin plates represents a promising platform for bioanalysis of biotherapeutics.

Recent advancements, challenges, and practical considerations in the mass spectrometry-based analytics of protein biotherapeutics: A viewpoint from the biosimilar industry

The extensive analytical characterization of protein biotherapeutics, especially of biosimilars, is a critical part of the product development and registration. High-resolution mass spectrometry became the primary analytical tool used for the structural characterization of biotherapeutics. Its high instrumental sensitivity and methodological versatility made it possible to use this technique to characterize both the primary and higher-order structure of these proteins. However, even by using high-end instrumentation, analysts face several challenges with regard to how to cope with industrial and regulatory requirements, that is, how to obtain accurate and reliable analytical data in a time- and cost-efficient way. New sample preparation approaches, measurement techniques and data evaluation strategies are available to meet those requirements. The practical considerations of these methods are discussed in the present review article focusing on hot topics, such as reliable and efficient sequencing strategies, minimization of artefact formation during sample preparation, quantitative peptide mapping, the potential of multi-attribute methodology, the increasing role of mass spectrometry in higher-order structure characterization and the challenges of MS-based identification of host cell proteins. On the basis of the opportunities in new instrumental techniques, methodological advancements and software-driven data evaluation approaches, for the future one can envision an even wider application area for mass spectrometry in the biopharmaceutical industry.

Quantifying hormones in exhaled breath for physiological assessment of large whales at sea

Exhaled breath analysis is a non-invasive assessment tool that has shown promise in human diagnostics, and could greatly benefit research, management, and conservation of large whales. However, hormone assessment of whale respiratory vapor (blow) has been challenged by variable water content and unknown total volume of collected samples. To advance this technique, we investigated urea (a compound present in narrow range in circulation) as a normalizing factor to correct for blow sample concentration. Normalized progesterone, testosterone, and cortisol concentrations of 100 blow samples from 46 photo-identified North Atlantic right whales (Eubalaena glacialis) were more biologically relevant compared to absolute estimates, varying by sex, age class, or individual. Progesterone was elevated in adult females compared with other cohorts and highest in one independently confirmed pregnant female. For both sexes, testosterone was two-fold higher in reproductively mature whales but studied adult females showed the widest variation. Cortisol was present in relatively low concentrations in blow and demonstrated variation between individual whales, suggesting potential for studies of individual differences in adrenal activity. Incorporation of methodologies that normalize sample concentration are essential for blow hormone analysis of free-swimming whales, and measurement of urea could be used to optimize non-invasive physiological assessment of whales.

Development and validation of a new analytical HPLC method for simultaneous determination of the antidiabetic drugs, metformin and gliclazide

An efficient and simple HPLC method has been developed and validated for the simultaneous determination of gliclazide and metformin hydrochloride in bulk and was applied on marketed metformin and gliclazide products. The mobile phase used for the chromatographic runs consisted of 20 mM ammonium formate buffer (pH 3.5) and acetonitrile (45:55, v/v) The separation was achieved on an Alltima CN (250 mm × 4.6 mm x 5μ) column using isocratic mode. Drug peaks were well separated and were detected by a UV detector at 227 nm. The method was linear at the concentration range 1.25–150 μg/ml for gliclazide and 2.5–150 μg/ml for metformin respectively. The method has been validated according to ICH guidelines with respect to system suitability, specificity, precision, accuracy and robustness. Metformin limit of detection (LOD) and limit of quantification (LOQ) were 0.8 μg/ml and 2.45 μg/ml respectively while LOD and LOQ for gliclazide were 0.97 μg/ml and 2.95 μg/ml respectively.

Improving selectivity and sensitivity of protein quantitation by LC–HR–MS/MS: determination of somatropin in rat plasma

Aim: Protein quantitation by digestion of a biological sample followed by LC–MS analysis of a signature peptide can be a challenge because of the high complexity of the digested matrix. Results/methodology: The use of LC with high-resolution (quadrupole-TOF) MS detection allowed quantitation of the 22-kDa biopharmaceutical somatropin in 60 μl of rat plasma down to 25 ng/ml with minimal further sample treatment. Reducing the mass extraction window to 0.01 Da considerably decreased the interference of tryptic peptides, enhanced sensitivity and improved accuracy and precision. Analysis with LC–MS/MS resulted in a less favorable limit of quantitation of 100 ng/ml. Conclusion: HRMS is an interesting option for the quantitation of proteins after digestion and has the potential to improve sensitivity with minimal method development.

Critical considerations for immunocapture enrichment LC–MS bioanalysis of protein therapeutics and biomarkers

In recent years, immunocapture enrichment coupled with LC–MS technology has seen more applications for the measurement of low abundant protein therapeutics and biomarkers in biological matrices. In this article, several critical considerations for the application of immunocapture enrichment to LC–MS bioanalysis of protein therapeutics and biomarkers, including reagent selection, reagent characterization, designing of capture format, etc. are discussed. All these considerations are critical in developing reliable and robust bioanalytical assays with high assay specificity and sensitivity. Successful examples using the immunocapture LC–MS approach in the quantification of biotherapeutic and low abundant protein biomarkers will also be discussed.

Development of an automated, interference-free, 2D-LC–MS/MS assay for quantification of a therapeutic mAb in human sera

Aim: Hybrid LC–MS/MS assays are increasingly used to quantitate proteins in biological matrices. These assays involve analyte enrichment at the protein level. Although suitability has been demonstrated, they are limited by the lack of appropriate affinity reagents and may suffer from interferences caused by binding proteins or antibodies. Results: An online stable isotope standards and capture by anti-peptide antibodies assay was developed, which involves tryptic digestion of a therapeutic monoclonal antibody in human serum to destroy interfering proteins followed by enrichment using high affinity peptide antibodies. The assay was validated and compared with a standard ligand-binding assay currently used for quantification. Conclusion: The data show that the stable isotope standards and capture by anti-peptide antibodies-2D-LC–MS/MS assay can be used as an alternative method for measurement of monoclonal antibodies in clinical samples.

Streptomyces spp. From Ethiopia Producing Antimicrobial Compounds: Characterization via Bioassays, Genome Analyses, and Mass Spectrometry

A total of 416 actinomycete cultures were isolated from various unique environments in Ethiopia and tested for bioactivity. Six isolates with pronounced antimicrobial activity were chosen for taxonomic identification and further investigation. Morphological and cultural properties of the isolates were found to be consistent with those of the genus Streptomyces, which was further confirmed by phylogenetic analysis based on 16S rRNA gene sequences. One of the isolates, designated Streptomyces sp. Go-475, which displayed potent activity against both pathogenic yeasts and Gram-positive bacteria, was chosen for further investigation. Metabolite profiles and bioactivity of Go-475 incubated on wheat bran-based solid and soya flour-based liquid media were compared using high-resolution LC-MS. This allowed identification of several known compounds, and suggested the ability of Go-475 to produce new secondary metabolites. Major anti-bacterial compounds were purified from liquid cultures of Go-475, and their structures elucidated by NMR and HRMS as 8-O-methyltetrangomycin and 8-O-methyltetrangulol. In addition, many potentially novel metabolites were detected, the majority of which were produced in solid media-based fermentation. The genome sequence of Streptomyces sp. Go-475 was obtained using a hybrid assembly approach of high quality Illumina short read and low quality Oxford Nanopore long read data. The complete linear chromosome of 8,570,609 bp, featuring a G+C content of 71.96%, contains 7,571 predicted coding sequences, 83 t(m)RNA genes, and six rrn operons. Analysis of the genome for secondary metabolite biosynthesis gene clusters further confirmed potential of this isolate to synthesize chemically diverse natural products, and allowed to connect certain clusters with experimentally confirmed molecules.

LC-HRMS Metabolomics for Untargeted Diagnostic Screening in Clinical Laboratories: A Feasibility Study

Today’s high-resolution mass spectrometers (HRMS) allow bioanalysts to perform untargeted/global determinations that can reveal unexpected compounds or concentrations in a patient’s sample. This could be performed for preliminary diagnosis attempts when usual diagnostic processes and targeted determinations fail. We have evaluated an untargeted diagnostic screening (UDS) procedure. UDS is a metabolome analysis that compares one sample (e.g., a patient) with control samples (a healthy population). Using liquid chromatography (LC)-HRMS full-scan analysis of human serum extracts and unsupervised data treatment, we have compared individual samples that were spiked with one xenobiotic or a higher level of one endogenous compound with control samples. After the use of different filters that drastically reduced the number of metabolites detected, the spiked compound was eventually revealed in each test sample and ranked. The proposed UDS procedure appears feasible and reliable to reveal unexpected xenobiotics (toxicology) or higher concentrations of endogenous metabolites. HRMS-based untargeted approaches could be useful as preliminary diagnostic screening when canonical processes do not reveal disease etiology nor establish a clear diagnosis and could reduce misdiagnosis. On the other hand, the risk of overdiagnosis of this approach should be reduced with mandatory biomedical interpretation of the patient’s UDS results and with confirmatory targeted and quantitative determinations.