Pooled Human Serum Research Articles

Commercial insulin immunoassays fail to detect commonly prescribed insulin analogues

ObjectivesBlood insulin and C-peptide are key investigations in the differential diagnosis of hypoglycaemia. Analogues of insulin have modified primary-sequences compared to native human insulin, as such may not cross react with insulin assays. This has important implications in detecting surreptitious or malicious insulin administration.The aim of this study is to assess the cross-reactivity of all insulins currently listed in the British National Formulary (BNF65, 2013) in clinical insulin assays currently used in UK clinical laboratories. Design and methodsSample sets were prepared for all 15 exogenous insulin classes listed in the BNF, at concentrations of 1000pmol/L and 300pmol/L, using pooled human serum. Samples were sent blinded to 5 participating analytical laboratories to cover analysis on the 10 major clinical insulin assays used in the UK. ResultsThe ability of insulin assays to detect exogenous insulin preparations was highly variable and ranged from 0% to >140% for a single exogenous insulin. Four assays were highly specific for the human insulin sequence and had no cross-reactivity with any synthetic analogue insulin. Two detected all insulin types (human sequence, animal and synthetic analogue), with the remaining having variable cross-reactivity. ConclusionThe cross-reactivity of the 15 exogenous insulin preparations is highly variable in the assays used in clinical laboratories around the UK. It is important that laboratories and clinicians are aware of the limitations of their local assays to avoid missing the important diagnosis of hypoglycaemia secondary to excessive exogenous insulin. Where necessary, samples should be referred to specialist centres for insulin analysis and ideally by a validated and fully-quantitative mass spectrometry-based method.

D-amino carboxamide-based recruitment of dinitrophenol antibodies to bacterial surfaces via peptidoglycan remodeling.

During the past few decades there has been a rapid emergence of multidrug resistant bacteria afflicting human patients. At the same time, reduced output from pharmaceutical industry in this area precipitated a sharp decrease in the approval of new antibiotics. The combination of these factors potentially compromises the ability to effectively combat bacterial infections. While traditional drug discovery efforts continue in the pursuit of small molecule agents that disrupt bacterial growth, non-traditional efforts could serve to complement antimicrobial strategies. We recently demonstrated our ability to remodel the surface of bacterial cells using unnatural D-amino acids displaying the antigenic dinitrophenyl (DNP) handle. These immune stimulant D-amino acids derivatives were metabolically incorporated onto the peptidoglycan of bacteria via a promiscuous surface-anchored transpeptidase. The covalent modification of DNP moieties onto the peptidoglycan led to the anti-DNP antibody opsonization of the bacterial cell surface. Herein, we show that the amidation of the C-terminus to generate DNP-displaying D-amino carboxamide drastically improves antibody recruitment. Antibody opsonization using the D-amino carboxamide agent is observed at lower concentrations than the D-amino acid counterpart. In addition, the recruitment of endogenous antibodies in pooled human serum to the DNP-modified bacterial cell surface is demonstrated for the first time. We envision that the C-terminus amidation of DNP-conjugated D-amino acids could potentially facilitate translation of these results to in vivo animal disease models.

Development of recombinant antibodies for reliable and sensitive food allergen detection

Around 4 % of the population suffer from IgE-mediated food allergies in Western countries and the number of food-allergenic people is increasing. Individuals with certain pollen allergies may also suffer from a sensitisation to proteins in the foods. As an example a person sensitised to the major birch pollen allergen, Bet v 1, is often sensitised to its homologues, such as the major allergens of apple, Mal d 1, and celery, Api g 1, as well. Development of diagnostic tools for the reliable, sensitive and quick detection of allergens present in various food products are essential for allergic persons to prevent the consumption of substances causing mild and even life-threatening immune responses. Traditionally the diagnostics of allergens are based on the use of human IgE serum pools isolated from allergic patients. The use of monoclonal antibodies would ensure the specific detection of the harmful food content for a sensitised person. The production of functional antibody fragments and their efficient display on the filamentous phage have made it possible to construct large and diverse antibody phage display libraries for the isolation of recombinant antibodies. Aim of the study was to construct mouse IgG antibody libraries from immunised mice. The selection of the resulting libraries was carried out using recombinant allergens, rMal d 1 and rApi g 1 which were produced as soluble non-fusion proteins in bacterial cells and purified by a conventional chromatography. The binding properties of the isolated Fab fragments towards the recombinant allergens and native allergens from natural sources were characterised. Interestingly, isolated Mal d 1 -specific antibody bound also to Bet v 1, the main allergen eliciting the cross-reactivity syndrome between the birch pollen and apple. Despite the similarities in protein tertiary structure, there was no observable cross-reactivity between Api g 1 -specific antibodies and Bet v 1 in this study. Isolated allergen-specific antibodies can be utilised as diagnostic and research tools for the specific and reliable detection of allergens from different consumable products as well as studying allergy-antibody interactions.

Massive glutamine cyclization to pyroglutamic acid in human serum discovered using NMR spectroscopy.

Glutamine is one of the most abundant metabolites in blood and is a precursor as well as end product central to numerous important metabolic pathways. A number of surprising and unexpected roles for glutamine, including cancer cell glutamine addiction discovered recently, stress the importance of accurate analysis of glutamine concentrations for understanding its role in health and numerous diseases. Utilizing a recently developed NMR approach that offers access to an unprecedented number of quantifiable blood metabolites, we have identified a surprising glutamine cyclization to pyroglutamic acid that occurs during protein removal. Intact, ultrafiltered and protein precipitated samples from the same pool of human serum were comprehensively investigated using (1)H NMR spectroscopy at 800 MHz to detect and quantitatively evaluate the phenomenon. Interestingly, although glutamine cyclization occurs in both ultrafiltered and protein precipitated serum, the cyclization was not detected in intact serum. Strikingly, due to cyclization, the apparent serum glutamine level drops by up to 75% and, concomitantly, the pyroglutamic acid level increases proportionately. Further, virtually under identical conditions, the magnitude of cyclization is vastly different for different portions of samples from the same pool of human serum. However, the sum of glutamine and pyroglutamic acid concentrations in each sample remains the same for all portions. These unexpected findings indicate the importance of considering the sum of apparent glutamine and pyroglutamic acid levels, obtained from the contemporary analytical methods, as the actual blood glutamine level for biomarker discovery and biological interpretations.

Quantitation of permethylated N-glycans through multiple-reaction monitoring (MRM) LC-MS/MS.

The important biological roles of glycans and their implications in disease development and progression have created a demand for the development of sensitive quantitative glycomics methods. Quantitation of glycans existing at low abundance is still analytically challenging. In this study, an N-linked glycans quantitation method using multiple-reaction monitoring (MRM) on a triple quadrupole instrument was developed. Optimum normalized collision energy (CE) for both sialylated and fucosylated N-glycan was determined to be 30%, whereas it was found to be 35% for either fucosylated or sialylated N-glycans. The optimum CE for mannose and complex type N-glycan was determined to be 35%. Additionally, the use of three transitions was shown to facilitate reliable quantitation. A total of 88 N-glycan compositions in human blood serum were quantified using this MRM approach. Reliable detection and quantitation of these glycans was achieved when the equivalence of 0.005μL of blood serum was analyzed. Accordingly, N-glycans down to the 100th of a μL level can be reliably quantified in pooled human blood serum, spanning a dynamic concentration range of three orders of magnitude. MRM was also effectively utilized to quantitatively compare the expression of N-glycans derived from brain-targeting breast carcinoma cells (MDA-MB-231BR) and metastatic breast cancer cells (MDA-MB-231). Thus, the described MRM method of permethylated N-glycan enables a rapid and reliable identification and quantitation of glycans derived from glycoproteins purified or present in complex biological samples.

Development and evaluation of a SPR-based immunosensor for detection of anti-Trypanosoma cruzi antibodies in human serum

Protozoan Trypanosoma cruzi is the etiological agent of Chagas disease, which needs urgent progress in its immunological diagnosis. Surface plasmon resonance (SPR) is a promising technique for the development of immunosensors with biomedical applications. In this work, a SPR-based immunosensor has been developed by the first time for real time and label free immunoassay for detection of anti-T. cruzi antibodies in serum samples. T. cruzi antigen was successfully immobilized on a SPR sensor chip via activated mixed self-assembled monolayer (SAM) of 3-mercaptopropionic acid (3-MPA) and 11-mercaptoundecanoic acid (11-MUA), by amide coupling. After the sensor construction, a pool of human sera infected with T. cruzi was added to its surface and the antibodies were detected in sera diluted up to 1280 times, indicating excellent sensitivity of the technique for detection of antigen–antibody interaction. The addition of a pool of negative human serum at dilutions lower than 1:160 to the sensor surface was accompanied by a null or very low response. Then, the following operational parameters of the immunoassay were optimized and defined: time of immobilization and antigen concentration at 20min and 30mgmL−1, serum dilution at 1:320, preventing of nonspecific bindings with solution of BSA 1.0% and surface regeneration by injection of SDS 1.0%. The immunoassay, here termed SPRCruzi, showed high capability in the discrimination of positive and negative sera, including those infected with other pathogens usually sources of false positives results in conventional serodiagnosis. Therefore, the proposed immunosensor was successfully developed and the immunoassay allowed a simple, effective, faster and specific detection of anti-T. cruzi antibodies, which represents an encouraging field for the progress of the diagnosis of Chagas disease.

Metabolic profiling of bile acids in human and mouse blood by LC-MS/MS in combination with phospholipid-depletion solid-phase extraction.

To obtain a more comprehensive profile of bile acids (BAs) in blood, we developed an ultrahigh performance liquid chromatography/multiple-reaction monitoring-mass spectrometry (UPLC-MRM-MS) method for the separation and detection of 50 known BAs. This method utilizes phospholipid-depletion solid-phase extraction as a new high-efficiency sample preparation procedure for BA assay. UPLC/scheduled MRM-MS with negative ion electrospray ionization enabled targeted quantitation of 43 and 44 BAs, respectively, in serum samples from seven individuals with and without fasting, as well as in plasma samples from six cholestatic gene knockout mice and six age- and gender-matched wild-type (FVB/NJ) animals. Many minor BAs were identified and quantitated in the blood for the first time. Method validation indicated good quantitation precision with intraday and interday relative standard deviations of ≤9.3% and ≤10.8%, respectively. Using a pooled human serum sample and a pooled mouse plasma sample as the two representative test samples, the quantitation accuracy was measured to be 80% to 120% for most of the BAs, using two standard-substance spiking approaches. To profile other potential BAs not included in the 50 known targets from the knockout versus wild-type mouse plasma, class-specific precursor/fragment ion transitions were used to perform UPLC-MRM-MS for untargeted detection of the structural isomers of glycine- and taurine-conjugated BAs and unconjugated tetra-hydroxy BAs. As a result, as many as 36 such compounds were detected. In summary, this UPLC-MRM-MS method has enabled the quantitation of the largest number of BAs in the blood thus far, and the results presented have revealed an unexpectedly complex BA profile in mouse plasma.

Long-term in vitro cultivation of Borrelia miyamotoi

Borrelia are fastidious bacteria some of which are difficult to grow in vitro. Here, we report a method for successful continuous in vitro cultivation of the emerging pathogen Borrelia miyamotoi. The type and quantity of serum as well as the atmosphere were critical for successful in vitro cultivation. Optimal growth was achieved using 50% pooled human serum and an atmosphere of 6% CO2.

Expanding the limits of human blood metabolite quantitation using NMR spectroscopy.

A current challenge in metabolomics is the reliable quantitation of many metabolites. Limited resolution and sensitivity combined with the challenges associated with unknown metabolite identification have restricted both the number and the quantitative accuracy of blood metabolites. Focused on alleviating this bottleneck in NMR-based metabolomics, investigations of pooled human serum combining an array of 1D/2D NMR experiments at 800 MHz, database searches, and spiking with authentic compounds enabled the identification of 67 blood metabolites. Many of these (∼1/3) are new compared with those reported previously as a part of the Human Serum Metabolome Database. In addition, considering both the high reproducibility and quantitative nature of NMR as well as the sensitivity of NMR chemical shifts to altered sample conditions, experimental protocols and comprehensive peak annotations are provided here as a guide for identification and quantitation of the new pool of blood metabolites for routine applications. Further, investigations focused on the evaluation of quantitation using organic solvents revealed a surprisingly poor performance for protein precipitation using acetonitrile. One-third of the detected metabolites were attenuated by 10–67% compared with methanol precipitation at the same solvent-to-serum ratio of 2:1 (v/v). Nearly 2/3 of the metabolites were further attenuated by up to 65% upon increasing the acetonitrile-to-serum ratio to 4:1 (v/v). These results, combined with the newly established identity for many unknown metabolites in the NMR spectrum, offer new avenues for human serum/plasma-based metabolomics. Further, the ability to quantitatively evaluate nearly 70 blood metabolites that represent numerous classes, including amino acids, organic acids, carbohydrates, and heterocyclic compounds, using a simple and highly reproducible analytical method such as NMR may potentially guide the evaluation of samples for analysis using mass spectrometry.

T Cells in CTCL Have an Exhausted Phenotype While Cutaneous Dendritic Cells Display a Normally Activated Mature Phenotype

Background: Mycosis fungoides (MF) and Sézary syndrome (SS) represent the most common types of cutaneous T-cell lymphoma (CTCL). CTCL develops from clonally-expanded, effector/central memory CD4+ T cells in a background of chronic inflammation. The eliciting Ag(s) and how this inflammation contributes to the development and progression of CTCL remain important unknowns. Despite tumor-infiltrating CD8+ T cells in skin, the malignant CD4+ T-cell population persists, indicating that these CD8+ T cells cannot exert an effective anti-tumor response, potentially due to T-cell exhaustion, which has been observed in chronic viral infections and is associated with disease progression in hematologic malignancies like ATLL and CLL. Exhausted T-cells are characterized by immunoinhibitory molecules, like programmed death-1 (PD-1). Engagement of PD-1 by PD-Ligand (L)-1/L-2 transduces a signal that leads to inhibition of T-cell functions, but the cells are not deleted. PD-L1 is expressed on T cells, dendritic cells (DCs), and many tumor cells, whereas PD-L2 expression is limited to antigen-presenting cells. Although malignant CD4+ T cells in Sézary syndrome lesions express PD-1, the relevance of the PD-1/PD-L1/2 pathway in CTCL and the immune cells in CTCL that express PD-L1/L2 are not known.Methods: Epidermis and dermis of skin biopsies from consented CTCL pts (12) and healthy donors (3) were separated using dispase-II and incubated in RPMI-10% pooled human serum for 24 hrs. Migrated cutaneous T cells and DCs were phenotyped by flow cytometry for a variety of maturation markers and immune checkpoint molecules. In 3 pts skin findings were compared with matched PBMCs.Results: Freshly isolated cutaneous CD8+ T cells displayed distinct effector and memory subsets with a higher frequency of effector-memory (CD28-CD45RA-CCR7-) and terminally differentiated effector cells (CD28-CD45RA+CCR7-). In addition, CD8+ T-cells exhibited enhanced expression of PD-1, Lag-3, Tim-3, and ICOS. PD-1 was the receptor most overexpressed in CD8+ T cells compared with healthy controls. PD-1 expression on circulating CD8+ T cells was lower compared with skin-infiltrating CD8+ T-cells. In contrast, the malignant CD4+ T-cells expressed predominantly a central memory or transient memory subtype (CD28+CD45RA-CCR7+/-), with overexpression of PD-1, CTLA-4, Lag-3, and ICOS. Immune-suppressive CD3+CD4+FoxP3+CD127-Tregs were not increased in PBMCs of CTCL pts. Migrated DCs displayed an activated, mature phenotype expressing HLA-DR+, CD1a+/-, CD207 (Langerin)+/-, CD14+/-, CD11c+, CD83low/med, CD86low/med and PD-L1+/- phenotype.Conclusion: Both the malignant CD4+ T cells and tumor-infiltrating CD8+ T cells display an exhausted phenotype, while DC subsets display a normal activated phenotype. Our preliminary data imply a role for PD-1 and other checkpoint molecules like ICOS, Tim-3, Lag-3 in attenuating the anti-tumor response. Studies are underway in vitro to establish the function of PD-1, Lag-3, Tim-3, and ICOS on T cells in response to DC/LC stimulation to develop a rationale for therapeutic checkpoint blockade inhibitors to reverse the exhausted T cell phenotype and attendant lack of immune reactivity. DisclosuresNo relevant conflicts of interest to declare.

Performance characteristics of the Beckman Coulter total βhCG (5th IS) assay

BackgroundBeckman Coulter recently released the first commercially available hCG reagent calibrated against the 5th International Standard (IS) for hCG (total βhCG (5th IS)). We performed a comprehensive analytical validation of this reagent. MethodsPrecision experiments were completed using 3 concentrations of commercial quality control material. Linearity, sample stability, and analytical sensitivity were evaluated using pools of human serum. Reportable range was assessed by comparing manual dilutions to those performed by the instrument. Male and female reference intervals were established using residual serum specimens submitted for routine testing. Inter-lot variability of hCG assay reagent was assessed by analyzing serum specimens with detectable hCG using 2 different reagent lots. Inter-assay variability was established using 203 serum specimens analyzed for hCG on 6 different reagent platforms. ResultsInter-day precision showed a CV of <6.0% for all concentrations of QC material. LOB, LOD, and LOQ were determined to be 0.3, 0.4, and 0.6U/l, respectively. The Access (5th IS) reagent has an average positive bias of approximately 20% when compared to most platforms and the previous generation Beckman hCG assay. Results were consistent between lots. Female reference intervals varied by age: <1.0U/l (<41y), <6.0U/l (41–50y), and <8.0U/l (>50y). Male reference intervals were <2.0U/l. ConclusionsThe analytical performance of the total βhCG (5th IS) was established. Care should be taken to re-baseline patients needing serial monitoring and/or notify physicians when transitioning to the total βhCG (5th IS) reagent.

Commutability of possible external quality assessment materials for cardiac troponin measurement.

BackgroundThe measurement of cardiac troponin is crucial in the diagnosis of myocardial infarction. The performance of troponin measurement is most conveniently monitored by external quality assessment (EQA) programs. The commutability of EQA samples is often unknown and the effectiveness of EQA programs is limited.MethodsCommutability of possible EQA materials was evaluated. Commercial control materials used in an EQA program, human serum pools prepared from patient samples, purified analyte preparations, swine sera from model animals and a set of patient samples were measured for cTnI with 4 assays including Abbott Architect, Beckman Access, Ortho Vitros and Siemens Centaur. The measurement results were logarithm-transformed, and the transformed data for patient samples were pairwise analyzed with Deming regression and 95% prediction intervals were calculated for each pair of assays. The commutability of the materials was evaluated by comparing the logarithmic results of the materials with the limits of the intervals. Matrix-related biases were estimated for noncommutable materials. The impact of matrix-related bias on EQA was analyzed and a possible correction for the bias was proposed.ResultsHuman serum pools were commutable for all assays; purified analyte preparations were commutable for 2 of the 6 assay pairs; commercial control materials and swine sera were all noncommutable; swine sera showed no reactivity to Vitros assay. The matrix-related biases for noncommutable materials ranged from −83% to 944%. Matrix-related biases of the EQA materials caused major abnormal between-assay variations in the EQA program and correction of the biases normalized the variations.ConclusionCommutability of materials has major impact on the effectiveness of EQA programs for cTnI measurement. Human serum pools prepared from patient samples are commutable and other materials are mostly noncommutable. EQA programs should include at least one human serum pool to allow proper interpretation of EQA results.

Erythrocytes from GGTA1/CMAH knockout pigs: implications for xenotransfusion and testing in non-human primates.

Pig erythrocytes are potentially useful to solve the worldwide shortage of human blood for transfusion. Domestic pig erythrocytes, however, express antigens that are bound by human preformed antibodies. Advances in genetic engineering have made it possible to rapidly knock out the genes of multiple xenoantigens, namely galactose α1,3 galactose (aGal) and N-glycolylneuraminic acid (Neu5Gc). We have recently targeted the GGTA1 and CMAH genes with zinc finger endonucleases resulting in double knockout pigs that no longer express aGal or Neu5Gc and attract significantly fewer human antibodies. In this study, we characterized erythrocytes from domestic and genetically modified pigs, baboons, chimpanzees, and humans for binding of human and baboon natural antibody, and complement-mediated lysis. Distribution of anti-Neu5Gc IgG and IgM in pooled human AB serum was analyzed by ELISA. Erythrocytes from domestic pigs (Dom), aGal knockout pigs (GGTA1 KO), aGal and Neu5Gc double knockout pigs (GGTA1/CMAH KO), baboons, chimpanzees, and humans were analyzed by flow cytometry for aGal and Neu5Gc expression. In vitro comparative analysis of erythrocytes was conducted with pooled human AB serum and baboon serum. Total antibody binding was accessed by hemagglutination; complement-dependent lysis was measured by hemolytic assay; IgG or IgM binding to erythrocytes was characterized by flow cytometry. The pooled human AB serum contained 0.38 μg/ml anti-Neu5Gc IgG and 0.085 μg/ml anti-Neu5Gc IgM. Both Gal and Neu5Gc were not detectable on GGTA1/CMAH KO erythrocytes. Hemagglutination of GGTA1/CMAH KO erythrocytes with human serum was 3.5-fold lower compared with GGTA1 KO erythrocytes, but 1.6-fold greater when agglutinated with baboon serum. Hemolysis of GGTA1/CMAH KO erythrocytes by human serum (25%) was reduced 9-fold compared with GGTA1 KO erythrocytes, but increased 1.64-fold by baboon serum. Human IgG binding was reduced 27-fold on GGTA1/CMAH KO erythrocytes compared with GGTA1 KO erythrocytes, but markedly increased 3-fold by baboon serum IgG. Human IgM binding was decreased 227-fold on GGTA1/CMAH KO erythrocytes compared with GGTA1 KO erythrocytes, but enhanced 5-fold by baboon serum IgM. Removal of aGal and Neu5Gc antigens from pig erythrocytes significantly reduced human preformed antibody-mediated cytotoxicity but may have complicated future in vivo analysis by enhancing reactivity from baboons. The creation of the GGTA1/CMAH KO pig has provided the xenotransplantation researcher with organs and cells that attract fewer human antibodies than baboon and our closest primate relative, chimpanzee. These finding suggest that while GGTA1/CMAH KO erythrocytes may be useful for human transfusions, in vivo testing in the baboon may not provide a direct transplantation to the clinic.

OP0188 Circulating Mirnas as Potential Biomarkers of Therapy Effectiveness in Rheumatoid Arthritis Patients Treated with Anti-TNF

BackgroundThe advent of anti-TNFα drugs has considerably improved medical management in Rheumatoid Arthritis (RA) patients, although it has been reported to be ineffective in a fraction of them. MicroRNAs (miRNAs)...

Allergenicity of Potato Proteins and of Their Conjugates with Galactose, Galactooligosaccharides, and Galactan in Native, Heated, and Digested Forms

The effect of glycation of potato proteins on their immunoreactivity was studied by using a pool of human sera with specific IgE to potato proteins. Patatin conjugates were more immunoreactive than protease inhibitors ones. To better understand this behavior, the changes in patatin structure upon glycation and heat treatment were investigated. Patatin demonstrated an increase in total immunoreactivity when glycated with galactose and galactooligosaccharides. However, galactan conjugation to patatin resulted in a decrease in immunoreactivity by restricting IgE's access to the epitopes. Although the heat treatment resulted in a decrease in patatin's immunoreactivity through aggregation, it was less effective when patatin conjugates were used due to the decrease in aggregation and the secondary structural changes. Upon digestion, native patatin exhibited the largest decrease in immunoreactivity resulting from the disruption of both conformational and sequential epitopes. Patatin conjugates were less digested and had higher IgE-immunoreactivity as compared to the digested patatin.

Estimated Secondary Structure Propensities within V1/V2 Region of HIV gp120 Are an Important Global Antibody Neutralization Sensitivity Determinant

BackgroundNeutralization sensitivity of HIV-1 virus to antibodies and anti-sera varies greatly between the isolates. Significant role of V1/V2 domain as a global neutralization sensitivity regulator has been suggested. Recent X-ray structures revealed presence of well-defined tertiary structure within this domain but also demonstrated partial disorder and conformational heterogeneity.MethodsCorrelations of neutralization sensitivity with the conformational propensities for beta-strand and alpha-helix formation over the entire folded V1/V2 domain as well as within sliding 5-residue window were investigated. Analysis was based on a set of neutralization data for 106 HIV isolates for which consistent neutralization sensitivity measurements against multiple pools of human immune sera have been previously reported.ResultsSignificant correlation between beta-sheet formation propensity of the folded segments of V1/V2 domain and neutralization sensitivity was observed. Strongest correlation peaks localized to the beta-strands B and C. Correlation persisted when subsets of HIV isolates belonging to clades B, C and circulating recombinant form BC where analyzed individually or in combinations.ConclusionsObserved correlations suggest that stability of the beta-sheet structure and/or degree of structural disorder in the V1/V2 domain is an important determinant of the global neutralization sensitivity of HIV-1 virus. While specific mechanism is to yet to be investigated, plausible hypothesis is that less ordered V1/V2s may have stronger masking effect on various neutralizing epitopes, perhaps effectively occupying larger volume and thereby occluding antibody access.

Concentrations and relationships between classes of persistent halogenated organic compounds in pooled human serum samples and air from Laizhou Bay, China

Persistent halogenated organic compounds, including polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polybrominated diphenyl ethers (PBDEs), dechlorane plus (DP), pentabromobenzene (PBBz), and pentabromotoluene (PBT), were analyzed in pooled human serum samples from different age groups and air samples from the south coast of Laizhou Bay, Shandong Province, China. The ∑25OCP and ∑8PBDE congeners were found at higher concentrations than the other compounds, with mean concentrations of 1500 and 240ng/g lipid in serum and 330 and 140000pg/m3 in the air, respectively. PBBz and PBT were detected in every serum and air sample, with mean concentrations of 4.9 and 1.4ng/g lipid in serum and 100 and 250pg/m3 in air, respectively. In serum, the mean concentrations of ∑14PCBs and ∑DP were 7.1 and 3.6ng/g lipid, respectively, and in air, the mean concentrations of ∑12dioxin-like (DL-) PCBs and ∑DP were 1.7 and 1.4pg/m3, respectively. Different relationships were observed between the concentrations of different compounds in serum and the volunteers' ages, and the concentration distributions with age were closely related to the historic production and usage volumes of each chemical in China. The ubiquity of PCBs, OCPs, PBDEs, DP, PBBz, and PBT in serum and air is potentially concerning, and effective measures should be taken to control the concentrations of these chemicals in the environment and humans. Significant correlations were found between the chemical concentrations in serum and air, suggesting that inhalation may be an important exposure route for the residents of Laizhou Bay.

Activity of a group B oncolytic adenovirus (ColoAd1) in whole human blood

Intravenous (i.v.) delivery of therapeutic viruses to human patients exposes virus particles to the potentially neutralising environment of the human bloodstream, where many components of the innate and adaptive immune system provide a formidable barrier to virus infection of target cells. Here we assess the haemocompatibility of ColoAd1, an oncolytic adenovirus currently undergoing clinical assessment for treatment of disseminated cancer by i.v. delivery. Compared with the commonly used serotype Ad5, ColoAd1 (which has a capsid derived from Ad11p) showed only minor inhibition of oncolytic activity by pooled human serum or washed human blood cells, with the amount of ColoAd1 required to kill cancer cells in vitro (the IC50) increasing <10-fold. However, some virus-blood interactions are concentration- and context-dependent, requiring study in whole, undiluted, human blood. ColoAd1 showed <50-fold increases in the IC50 in whole blood from most donors, whereas the activity of Ad5 was ablated. Extrapolating these findings to the clinical situation indicates that ColoAd1 would 'breakthrough' neutralisation in some patients receiving as few as 10(10) ColoAd1 particles i.v., and in most patients receiving doses of 10(12) or above, well within the achievable dose range.

Study on the quantity value transfer of enzymes from the reference measurement system

Objective Using the frozen human-pooled serum samples，with values assigned by the enzyme reference procedure in laboratory network to explore the way of quantity value transfer from enzyme reference measurement system to routine ones. Methods The study is about quantity value transfer. The frozen human-pooled serum sample was assigned by the enzyme reference laboratory network including six domestic reference procedure laboratories，namely Beijing Chaoyang Hospital affiliate of Capital University of Medical Sciences, Beijing Aerospace general Hospital, Beijing Shijitan Hospital affiliate of Capital University of Medical Sciences, Peking Union Medical College Hospital, Beijing Leadman Biochemistry Co.,Ltd. and Sichuan Maker Biotechnology Co.,Ltd., which used the reference measurement procedures of creatine kinase (CK) and lactate dehydrogenase (LDH) from the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) . First, the assigned serum was used to calibrate or verify trueness of routine measurement systems from the 49 laboratories of tertiary hospitals in Beijing in Feb,2013 by Beijing Center for Clinical Laboratories. Second, the assigned serum and two levels of patient samples were tested in duplicate by laboratory's measurement systems after calibration with manufacturer′s calibrator and with assigned serum. During this procedure, all laboratories data were collected. Harmonization of results was observed after calibration with the assigned serum according to the statistics. Results After calibration, the interlaboratory coefficients of variation (CVs) of two patient samples were decreased from 4.67% and 5.96% to 1.86% and 1.47% for CK and from 5.72% and 5.04% to 3.67% and 3.62% for LDH. For peer group of A and B instrument , after calibration, both CVs of the assigned serum and two patient samples were less than 2% for CK, and less than 4% for LDH ; For C instrument group, which was not calibrated with the assigned serum ,the biases were -4.75% for CK and -13.1% for LDH, while the biggest CVs were 3.64% for CK and 7.57% for LDH. For peer group of reagents, after calibration, the CVs were decreased from 1.60%-4.44% to 0.23%-1.62% for CK and from 0.93%-6.07% to 1.06%-2.72% for LDH. Conclusions It is one of the feasible ways for quantity value transfer by using the frozen human-pooled serum samples, which were assigned by the enzyme reference laboratory network for calibration or verification. It can effectively solve the problem of trueness and harmonization of enzyme testing results. In addition, for those measurement systems which are not applicable for this calibration.（Chin J Lab Med，2014,37：110-114） Key words: Enzymes; Clinical chemistry tests; Reference standards; Quality control; Clinical laboratory information systems; International system of units

SST broth, a new serum free germ tube induction medium for identification of Candida albicans

Three serum free media viz, sucrose solution, starch solution and SST broth have been formulated. The objective of the present study was to evaluate these three different serum free media for induction of germ tubes by Candida albicans and to compare their efficacy with the pooled human serum. Out of 50 C. albicans isolates 47 (94%) and 49 (98%) produced germ tubes in pooled human serum and SST broth, respectively. Germ tube production was positive in 40 (80%) and 36 (72%) isolates, respectively in sucrose solution and starch solution. This study reports SST broth as a new stable and less expensive germ tube induction medium, which requires less time for preparation and can be used without any safety concerns. SST broth is found to be more effective than pooled human serum for induction of germ tubes by C. albicans isolates.