Neuroprotective Action of Humanin and Humanin Analogues: Research Findings and Perspectives

Humanin is a 24-mer peptide first reported in the early 2000s as a new neuroprotective/cytoprotective factor rescuing neuronal cells from death induced by various Alzheimer's disease-associated insults. Nowadays it is known that humanin belongs to the novel class of the so-called mitochondrial-derived peptides (which are encoded by mitochondrial DNA) and has been shown to exert beneficial cytoprotective effects in a series of in vitro and/or in vivo experimental models of human diseases, including not only neurodegenerative disorders but other human diseases as well (e.g., age-related macular degeneration, cardiovascular diseases, or diabetes mellitus). This review article is focused on the presentation of recent in vitro and in vivo research results associated with the neuroprotective action of humanin as well as of various, mainly synthetic, analogues of the peptide; moreover, the main mode(s)/mechanism(s) through which humanin and humanin analogues may exert in vitro and in vivo regarding neuroprotection have been reported. The prospects of humanin and humanin analogues to be further investigated in the frame of future research endeavors against neurodegenerative/neural diseases have also been briefly discussed.

Immunosensors for Autoimmune-Disease-Related Biomarkers: A Literature Review

Immunosensors are a special class of biosensors that employ specific antibodies for biorecognition of the target analyte. Immunosensors that target disease biomarkers may be exploited as tools for disease diagnosis and/or follow-up, offering several advantages over conventional analytical techniques, such as rapid and easy analysis of patients' samples at the point-of-care. Autoimmune diseases have been increasingly prevalent worldwide in recent years, while the COVID-19 pandemic has also been associated with autoimmunity. Consequently, demand for tools enabling the early and reliable diagnosis of autoimmune diseases is expected to increase in the near future. To this end, interest in immunosensors targeting autoimmune disease biomarkers, mainly, various autoantibodies and specific pro-inflammatory proteins (e.g., specific cytokines), has been rekindled. This review article presents most of the immunosensors proposed to date as potential tools for the diagnosis of various autoimmune diseases, such as type 1 diabetes, rheumatoid arthritis, and multiple sclerosis. The signal transduction and the immunoassay principles of each immunosensor have been suitably classified and are briefly presented along with certain sensor elements, e.g., special nano-sized materials used in the construction of the immunosensing surface. The main concluding remarks are presented and future perspectives of the field are also briefly discussed.

Cortisol Immunosensors: A Literature Review

Cortisol is a steroid hormone that is involved in a broad range of physiological processes in human/animal organisms. Cortisol levels in biological samples are a valuable biomarker, e.g., of stress and stress-related diseases; thus, cortisol determination in biological fluids, such as serum, saliva and urine, is of great clinical value. Although cortisol analysis can be performed with chromatography-based analytical techniques, such as liquid chromatography-tandem mass spectrometry (LC-MS/MS), conventional immunoassays (radioimmunoassays (RIAs), enzyme-linked immunosorbent assays (ELISAs), etc.) are considered the "gold standard" analytical methodology for cortisol, due to their high sensitivity along with a series of practical advantages, such as low-cost instrumentation, an assay protocol that is fast and easy to perform, and high sample throughput. Especially in recent decades, research efforts have focused on the replacement of conventional immunoassays by cortisol immunosensors, which may offer further improvements in the field, such as real-time analysis at the point of care (e.g., continuous cortisol monitoring in sweat through wearable electrochemical sensors). In this review, most of the reported cortisol immunosensors, mainly electrochemical and also optical ones, are presented, focusing on their immunosensing/detection principles. Future prospects are also briefly discussed.

Fast and Accurate Determination of Minute Ochratoxin A Levels in Cereal Flours and Wine with the Label-Free White Light Reflectance Spectroscopy Biosensing Platform

Ochratoxin A (OTA) is one of the most toxic naturally encountered contaminants and is found in a variety of foods and beverages, including cereals and wine. Driven by the strict regulations regarding the maximum allowable OTA concentration in foodstuff and the necessity for on-site determination, the development of fast and sensitive methods for the OTA determination in cereal flours and wine samples, based on white light reflectance spectroscopy, is presented. The method relied on appropriately engineered silicon chips, on top of which an OTA-protein conjugate was immobilized. A polyclonal antibody against OTA was then employed to detect the analyte in the framework of a competitive immunoassay; followed by the subsequent addition of a biotinylated secondary antibody and streptavidin for signal enhancement. A small size instrument performed all assay steps automatically and the bioreactions were monitored in real time as the software converted the spectral shifts into effective biomolecular adlayer thickness increase. The assay developed had a detection limit of 0.03 ng/mL and a working range up to 200 ng/mL. The assay lasted 25 min (less than 1h, including calibrators/antibody pre-incubation) and was accomplished following a simple sample preparation protocol. The method was applied to corn and wheat flour samples and white and red wines with recovery values ranging from 87.2 to 111%. The simplicity of the overall assay protocol and convenient instrumentation demonstrates the potential of the immunosensor developed for OTA detection at the point of need.

Recent Developments in the Field of Optical Immunosensors Focusing on a Label-Free, White Light Reflectance Spectroscopy-Based Immunosensing Platform

Optical immunosensors represent a research field of continuously increasing interest due to their unique features, which can mainly be attributed to the high-affinity and specific antibodies they use as biorecognition elements, combined with the advantageous characteristics of the optical transducing systems these sensors employ. The present work describes new developments in the field, focusing on recent bioanalytical applications (2021–2022) of labeled and label-free optical immunosensors. Special attention is paid to a specific immunosensing platform based on White Light Reflectance Spectroscopy, in which our labs have gained specific expertise; this platform is presented in detail so as to include developments, improvements, and bioanalytical applications since the mid-2000s. Perspectives on the field are been briefly discussed as well, highlighting the potential of optical immunosensors to eventually reach the state of a reliable, highly versatile, and widely applicable analytical tool suitable for use at the Point-of-Care.

Prothymosin α and Its C-Terminal Immunoreactive Decapeptide Show no Evidence of Acute Toxicity: A Preliminary in Silico, in Vitro and in Vivo Investigation

BACKGROUND

Members of the α-thymosin family have long been studied for their immunostimulating properties. Among them, the danger-associated molecular patterns (DAMPs) prothymosin α (proTα) and its C-terminal decapeptide proTα(100-109) have been shown to act as immunomodulators in vitro, due to their ability to promote T helper type 1 (Th1) responses. Recently, we verified these findings in vivo, showing that both proTα and proTα(100-109) enhance antitumor-reactive T cell-mediated responses.

METHODS

In view of the eventual use of proTα and proTα(100-109) in humans, we investigated their safety profile in silico, in human leukocytes and cancer cells lines in vitro, and in immunocompetent mice in vivo, in comparison to the proTα derivative thymosin alpha 1 (Τα1), a 28-mer peptide extensively studied for its safety in clinical trials.

RESULTS

In silico prediction via computational tools showed that all three peptide sequences likely are non-toxic or do not induce allergic regions. In vitro, proTα, proTα(100-109) and Tα1 did not affect the viability of human cancer cell lines and healthy donor-derived leukocytes, did not promote apoptosis or alter cell cycle distribution. Furthermore, mice injected with proTα, proTα(100-109) and Tα1 at doses equivalent to the suggested dose regimen of Tα1 in humans, did not show signs of acute toxicity, whereas proTα and proTα(100-109) increased the levels of proinflammatory and Th1-type cytokines in their peripheral blood.

CONCLUSION

Our preliminary findings suggest that proTα and proTα(100-109), even at high concentrations, are non-toxic in vitro and in an acute toxicity model in vivo; moreover, we show that the two peptides retain their immunomodulatory properties in vivo and, eventually, could be considered for therapeutic use in humans.

IgY technology: Methods for developing and evaluating avian immunoglobulins for the in vitro detection of biomolecules

The term “IgY technology” was introduced in the literature in the mid 1990s to describe a procedure involving immunization of avian species, mainly laying hens and consequent isolation of the polyclonal IgYs from the “immune” egg yolk (thus avoiding bleeding and animal stress). IgYs have been applied to various fields of medicine and biotechnology. The present article will deal with specific aspects of IgY technology, focusing on the currently reported methods for developing, isolating, evaluating and storing polyclonal IgYs. Other topics such as current information on isolation protocols or evaluation of IgYs from different avian species are also discussed. Specific advantages of IgY technology (e.g., novel antibody specificities that may emerge via the avian immune system) will also be discussed. Recent in vitro applications of polyclonal egg yolk-derived IgYs to the field of disease diagnosis in human and veterinary medicine through in vitro immunodetection of target biomolecules will be presented. Moreover, ethical aspects associated with animal well-being as well as new promising approaches that are relevant to the original IgY technology (e.g., development of monoclonal IgYs and IgY-like antibodies through the phage display technique or in transgenic chickens) and future prospects in the area will also be mentioned.

Fast and Sensitive Determination of the Fungicide Carbendazim in Fruit Juices with an Immunosensor Based on White Light Reflectance Spectroscopy

Carbendazim is a systemic benzimidazole-type fungicide with broad-spectrum activity against fungi that undermine food products safety and quality. Despite its effectiveness, carbendazim constitutes a major environmental pollutant, being hazardous to both humans and animals. Therefore, fast and reliable determination of carbendazim levels in water, soil, and food samples is of high importance for both food industry and public health. Herein, an optical biosensor based on white light reflectance spectroscopy (WLRS) for fast and sensitive determination of carbendazim in fruit juices is presented. The transducer is a Si/SiO₂ chip functionalized with a benzimidazole conjugate, and determination is based on a competitive immunoassay format. Thus, for the assay, a mixture of an in-house developed rabbit polyclonal anti-carbendazim antibody with the standards or samples is pumped over the chip, followed by biotinylated secondary antibody and streptavidin. The WLRS platform allows for real-time monitoring of biomolecular interactions carried out onto the Si/SiO₂ chip by transforming the shift in the reflected interference spectrum caused by the immunoreaction to effective biomolecular adlayer thickness. The sensor is able to detect 20 ng/mL of carbendazim in fruit juices with high accuracy and precision (intra- and inter-assay CVs ≤ 6.9% and ≤9.4%, respectively) in less than 30 min, applying a simple sample treatment that alleviates any "matrix-effect" on the assay results and a 60 min preincubation step for improving assay sensitivity. Excellent analytical characteristics and short analysis time along with its small size render the proposed WLRS immunosensor ideal for future on-the-spot determination of carbendazim in food and environmental samples.

Rapid detection of mozzarella and feta cheese adulteration with cow milk through a silicon photonic immunosensor

Mozzarella di Bufala Campana and Feta are two cheeses with Protected Designation of Origin the fraudulent adulteration of which with bovine milk must be routinely checked to ensure that consumers actually buy these high-end products and avoid health issues related to bovine milk allergy. Here, we employed, for the first time, a silicon-based photonic immunosensor for the detection of mozzarella and feta adulteration with bovine milk. The photonic immunosensor used relies on Mach-Zehnder interferometers monolithically integrated along with their respective light sources on a silicon chip. A rabbit polyclonal antiserum raised against bovine κ-casein was used for the development of a competitive immunoassay realized in three steps, including a reaction with the antiserum, a biotinylated anti-rabbit IgG antibody, and streptavidin. The implementation of this assay configuration significantly reduced the non-specific signal due to the cheese matrix, and allowed completion of the assay in ∼9 min. After optimization of all assay conditions, bovine cheese could be quantified in mozzarella or feta at concentrations as low as 0.5 and 0.25% (w/w), respectively; both quantification limits were below the maximum allowable content of bovine milk in mozzarella and feta (1% w/w) according to the EU regulations. Equally important, the assays were reproducible with intra- and inter-assay coefficients of variation <10%, and exhibited a wide linear dynamic range that extended up to 50 and 25% (w/w) for mozzarella and feta, respectively. Taking into account its performance, the proposed immunosensor may be transformed to a new tool against fraudulent activities in the dairy industry.

In Vitro Immunodetection of Prothymosin Alpha in Normal and Pathological Conditions

Prothymosin alpha (ProTα) is a highly acidic polypeptide, ubiquitously expressed in almost all mammalian cells and tissues and consisting of 109 amino acids in humans. ProTα is known to act both, intracellularly, as an anti-apoptotic and proliferation mediator, and extracellularly, as a biologic response modifier mediating immune responses similar to molecules termed as "alarmins". Antibodies and immunochemical techniques for ProTα have played a leading role in the investigation of the biological role of ProTα, several aspects of which still remain unknown and contributed to unraveling the diagnostic and therapeutic potential of the polypeptide. This review deals with the so far reported antibodies along with the related immunodetection methodology for ProTα (immunoassays as well as immunohistochemical, immunocytological, immunoblotting, and immunoprecipitation techniques) and its application to biological samples of interest (tissue extracts and sections, cells, cell lysates and cell culture supernatants, body fluids), in health and disease states. In this context, literature information is critically discussed, and some concluding remarks are presented.

Antitumor Reactive T-Cell Responses Are Enhanced In Vivo by DAMP Prothymosin Alpha and Its C-Terminal Decapeptide

Prothymosin α (proTα) and its C-terminal decapeptide proTα(100-109) were shown to pleiotropically enhance innate and adaptive immune responses. Their activities have been broadly studied in vitro, focusing primarily on the restoration of the deficient immunoreactivity of cancer patients' leukocytes. Previously, we showed that proTα and proTα(100-109) act as danger-associated molecular patterns (DAMPs), ligate Toll-like receptor-4, signal through TRIF- and MyD88-dependent pathways, promote the maturation of dendritic cells and elicit T-helper type 1 (Th1) immune responses in vitro, leading to the optimal priming of tumor antigen-reactive T-cell functions. Herein, we assessed their activity in a preclinical melanoma model. Immunocompetent mice bearing B16.F1 tumors were treated with two cycles of proTα or proTα(100-109) together with a B16.F1-derived peptide vaccine. Coadministration of proTα or proTα(100-109) and the peptide vaccine suppressed melanoma-cell proliferation, as evidenced by reduced tumor-growth rates. Higher melanoma infiltration by CD3+ T cells was observed, whereas ex vivo analysis of mouse total spleen cells verified the in vivo induction of melanoma-reactive cytotoxic responses. Additionally, increased levels of proinflammatory and Th1-type cytokines were detected in mouse serum. We propose that, in the presence of tumor antigens, DAMPs proTα and proTα(100-109) induce Th1-biased immune responses in vivo. Their adjuvant ability to orchestrate antitumor immunoreactivities can eventually be exploited therapeutically in humans.

Development of a specific IgY-based ELISA for prothymosin alpha, a bioactive polypeptide with diagnostic and therapeutic potential

Prothymosin alpha (ProTα) is a highly conserved polypeptide (109 amino acids in humans) with diagnostic and therapeutic potential; ProTα exerts intra- and extra-cellular biological functions associated with cell proliferation, apoptosis and immune regulation, while it has been suggested to act as a damage-associated molecular pattern (DAMP) or alarmin. In this work, chicken polyclonal anti-ProTα antibodies that had been developed several years ago were immunochemically evaluated and proven to retain immunoreactivity for ProTα, with remarkable thermal and pH stability. Moreover, the antibodies showed practically no cross-reactivity with a series of ProTα-fragments, eventually intracellularly produced -such as ProTα[1-28] (also known as Tα1) and ProTα[100-109], which exert per se biological activity and might be present in biological samples along with the intact molecule, being therefore highly specific for whole-length ProTα. Based on the above antibodies (IgYs-3e), a highly specific competitive ProTα-ELISA with well-studied analytical characteristics (intra- and inter-assay CVs: ≤5% and ≤12%, respectively, limit of detection: 2.1 ng/mL, recovery: 88–104%) was developed. The new ProTα-ELISA was applied to the analysis of supernatants of HeLa cells driven to necrosis; intact ProTα was measured in cell culture supernatants, at levels that seemed to depend on % cell necrosis.

Prothymosin Alpha: An Alarmin and More

BACKGROUND/OBJECTIVE

Prothymosin alpha (proTα) is a ubiquitous polypeptide first isolated by Haritos in 1984, whose role still remains partly elusive. We know that proTα acts both, intracellularly, as an anti-apoptotic and proliferation mediator, and extracellularly, as a biologic response modifier mediating immune responses similarly to molecules termed as "alarmins". Our research team pioneered the elucidation of the mechanisms underlying the observed activities of proTα.

RESULTS

We were the first to demonstrate that proTα levels increase during normal and abnormal cell proliferation. We showed that proTα acts pleiotropically, inducing immunomodulatory effects on immune cell populations. We revealed that the immunoreactive region of proTα is the carboxyterminal decapeptide proTα(100-109) and both molecules stimulate innate immune responses, signaling through Toll-like receptors (TLRs), specifically TLR-4. We reported that proTα and proTα(100-109) bind on the surface of human neutrophils on sites involving TLR-4, and cell activation is complemented by cytoplasmic calcium ion influx. Further, we showed that proTα and proTα(100-109) act as adjuvants upstream of lymphocyte stimulation and, in the presence of antigen, promote the expansion of antigen-reactive effectors. Most recently, we reported that proTα(100-109) may accumulate in experimentally inflamed sites and can serve as a surrogate biomarker in severe bacterial infections, proposing that extracellular release of proTα or proTα(100- 109) alerts the immune system during conditions of danger.

CONCLUSION

We, therefore, suggest that proTα, and likely proTα(100-109), act as alarmins, being important immune mediators as well as biomarkers, and could eventually become targets for new therapeutic/diagnostic approaches in immune-related diseases like cancer, inflammation, and sepsis.

In vivo biodistribution and imaging studies with a 99mTc-radiolabeled derivative of the C-terminus of prothymosin alpha in mice bearing experimentally-induced inflammation

Prothymosin alpha (ProTα) is a highly conserved mammalian polypeptide (109 amino acids in man) exerting in vitro and in vivo immunoenhancing activities. Recently, our team has developed a ^99mTc-radiolabeled derivative of the C-terminal bioactive decapeptide of ProTα ([^99mTc]C1) and employed it in in vitro studies, the results of which support the existence of binding sites on human neutrophils that recognize [^99mTc]C1, intact ProTα as well as the C-terminal decapeptide of ProTα and presumably involve Toll-like receptor 4. In the present work, [^99mTc]C1 was administered to Swiss albino mice with experimentally-induced inflammation for in vivo biodistribution and imaging studies, in parallel with a suitable negative control, which differs from [^99mTc]C1 only in bearing a scrambled version of the ProTα decapeptide. The biodistribution data obtained with [^99mTc]C1 demonstrated fast clearance of radioactivity from blood, heart, lungs, normal muscle, and predominantly urinary excretion. Most importantly, slow clearance of radioactivity from the inflammation focus was observed, resulting in a high ratio of inflamed/normal muscle tissue (9.15 at 30min post injection, which remained practically stable up to 2h). The inflammation-targeting capacity of [^99mTc]C1 was confirmed by imaging studies and might be attributed to neutrophils, which are recruited at the inflamed areas and bear binding sites for [^99mTc]C1. In this respect, apart from being a valuable tool for further studies on ProTα in in vitro and in vivo systems, [^99mTc]C1 merits further evaluation as a radiopharmaceutical for specific imaging of inflammation foci.

Antigen unmasking enhances visualization efficacy of the oocyte activation factor, phospholipase C zeta, in mammalian sperm

STUDY QUESTION

Is it possible to improve clinical visualization of phospholipase C zeta (PLCζ) as a diagnostic marker of sperm oocyte activation capacity and male fertility?

SUMMARY ANSWER

Poor PLCζ visualization efficacy using current protocols may be due to steric or conformational occlusion of native PLCζ, hindering antibody access, and is significantly enhanced using antigen unmasking/retrieval (AUM) protocols.

WHAT IS KNOWN ALREADY

Mammalian oocyte activation is mediated via a series of intracellular calcium (Ca²⁺) oscillations induced by sperm-specific PLCζ. PLCζ represents not only a potential clinical therapeutic in cases of oocyte activation deficiency but also a diagnostic marker of sperm fertility. However, there are significant concerns surrounding PLCζ antibody specificity and detection protocols.

STUDY DESIGN, SIZE DURATION

Two PLCζ polyclonal antibodies, with confirmed PLCζ specificity, were employed in mouse, porcine and human sperm. Experiments evaluated PLCζ visualization efficacy, and whether AUM improved this. Antibodies against two sperm-specific proteins [post-acrosomal WW-binding protein (PAWP) and acrosin] were used as controls.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Aldehyde- and methanol-fixed sperm were subject to immunofluorescence analysis following HCl exposure (pH = 0.1-0.5), acid Tyrode's solution exposure (pH = 2.5) or heating in 10 mM sodium citrate solution (pH = 6.0). Fluorescence intensity of at least 300 cells was recorded for each treatment, with three independent repeats.

MAIN RESULTS AND THE ROLE OF CHANCE

Despite high specificity for native PLCζ following immunoblotting using epitope-specific polyclonal PLCζ antibodies in mouse, porcine and human sperm, immunofluorescent visualization efficacy was poor. In contrast, sperm markers PAWP and acrosin exhibited relatively impressive results. All methods of AUM on aldehyde-fixed sperm enhanced visualization efficacy for PLCζ compared to visualization efficacy before AUM (P < 0.05 for all AUM interventions), but exerted no significant change upon PAWP or acrosin immunofluorescence following AUM. All methods of AUM enhanced PLCζ visualization efficacy in mouse and human methanol-fixed sperm compared to without AUM (P < 0.05 for all AUM interventions), while no significant change was observed in methanol-fixed porcine sperm before and after. In the absence of aldehyde-induced cross-linkages, such results suggest that poor PLCζ visualization efficacy may be due to steric or conformational occlusion of native PLCζ, hindering antibody access. Importantly, examination of sperm from individual donors revealed that AUM differentially affects observable PLCζ fluorescence, and the proportion of sperm exhibiting detectable PLCζ fluorescence in sperm from different males.

LIMITATIONS, REASONS FOR CAUTION

Direct correlation of fertility outcomes with the level of PLCζ in the sperm samples studied was not available. Such analyses would be required in future to determine whether the improved methodology for PLCζ visualization we propose would indeed reflect fertility status.

WIDER IMPLICATIONS OF THE FINDINGS

We propose that AUM alters conformational interactions to enhance PLCζ epitope availability and visualization efficacy, supporting prospective application of AUM to reduce misinterpretation in clinical diagnosis of PLCζ-linked male infertility. Our current results suggest that it is perhaps prudent that previous studies investigating links between PLCζ and fertility parameters are re-examined in the context of AUM, and may pave the way for future work to answer significant questions such as how PLCζ appears to be kept in an inactive form in the sperm.

LARGE SCALE DATA

Not applicable.

STUDY FUNDING/COMPETING INTERESTS

J.K. is supported by a Health Fellowship award from the National Institute for Social Care and Health Research (NISCHR). M.N. is supported by a Marie Curie Intra-European Research Fellowship award. This work was also partly funded by a research grant from Cook Medical Technologies LLC. There are no competing financial interests to declare.

Specific in vitro binding of a new (99m)Tc-radiolabeled derivative of the C-terminal decapeptide of prothymosin alpha on human neutrophils

Prothymosin alpha (ProTα) is a conserved mammalian polypeptide with intracellular functions associated with cell proliferation and apoptosis and an extracellular role associated with immunopotentiation. The N-terminal fragment [1-28], which is identical with the immunostimulating peptide thymosin α1 (Tα1), was earlier considered as the immunoactive region of the polypeptide; however, recent data suggest that ProTα may exert a discrete immunomodulating action through its central or C-terminal region, via targeting Toll-like receptor- 4 (TLR4). In this work, a derivative of the C-terminal fragment ProTα[100-109] (ProTα-D1) that can be radiolabeled with (99m)Tc was developed. The biological activity of the non-radioactive (185/187)rhenium-complex of this derivative ([(185/187)Re]ProTα-D1, structurally similar with [(99m)Tc]ProTα-D1) was verified through suitable in vitro bioassays on human neutrophils. Subsequent cell-binding studies revealed specific, time-dependent and saturable binding of [(99m)Tc]ProTα-D1 on neutrophils, which was inhibited by intact ProTα and ProTα[100-109], as well as by a "prototype" TLR4-ligand (lipopolysaccharide from Escherichia coli). Overall, our results support the existence of ProTα-binding sites on human neutrophils, recognizing [(99m)Tc]ProTα-D1, which might involve TLR4. [(99m)Tc]ProTα-D1 may be a useful tool for conducting further in vitro and in vivo studies, aiming to elucidate the extracellular mode of action of ProTα and, eventually, develop ProTα-based immunotherapeutics.

Commercially available chemicals as immunizing haptens for the development of a polyclonal antibody recognizing carbendazim and other benzimidazole-type fungicides

Carbendazim is a fungicide widely used for controlling fungi affecting fruits, vegetables, field crops etc. Determination of carbendazim in water, soil and various crops is frequently required to assure compliance with national/European regulations. A polyclonal antibody recognizing carbendazim was developed by using commercially available 2-(2-aminoethyl) benzimidazole, 2-benzimidazole propionic acid and 2-mercaptobenzimidazole as immunizing haptens; each of the above derivatives was directly conjugated to the carrier protein keyhole limpet hemocyanin and a mixture of the conjugates was administered to New Zealand white rabbits. Immunochemical functionality of the antisera and the corresponding isolated antibody (whole IgG fraction) was evaluated through titer and displacement curves in an in-house developed ELISA, which employed a 2-mercaptobenzimidazole - functionalized lysine-dendrimer as the immobilized hapten. As shown with ELISA-displacement curves, the above antibody could recognize carbendazim as well as other benzimidazole-type fungicides, i.e. benomyl and thiabendazole, and also intact benzimidazole, while it did not cross-react with the structurally different pesticides carbaryl and imazalil. Considering the rather simple approach which has led to its development and its highly promising immunochemical profile, the new antibody may be exploited in immunoanalytical systems for detecting benzimidazole-type pesticides e.g. in samples of environmental interest. The above antibody is being currently tested as a biorecognition element in the novel FOODSCAN cell biosensor platform for pesticide residue detection based on the Bioelectric Recognition Assay technology.

Visualization of the membrane engineering concept: evidence for the specific orientation of electroinserted antibodies and selective binding of target analytes

Membrane engineering is a generic methodology for increasing the selectivity of a cell biosensor against a target molecule, by electroinserting target-specific receptor-like molecules on the cell surface. Previous studies have elucidated the biochemical aspects of the interaction between various analytes (including viruses) and their homologous membrane-engineered cells. In the present study, purified anti-biotin antibodies from a rabbit antiserum along with in-house prepared biotinylated bovine serum albumin (BSA) were used as a model antibody-antigen pair of molecules for facilitating membrane engineering experiments. It was proven, with the aid of fluorescence microscopy, that (i) membrane-engineered cells incorporated the specific antibodies in the correct orientation and that (ii) the inserted antibodies are selectively interacting with the homologous target molecules. This is the first time the actual working concept of membrane engineering has been visualized, thus providing a final proof of the concept behind this innovative process. In addition, the fluorescence microscopy measurements were highly correlated with bioelectric measurements done with the aid of a bioelectric recognition assay.

Development and immunochemical evaluation of a novel chicken IgY antibody specific for KLK6

Background

Human kallikrein-related peptidase 6 (KLK6) has been implicated in various types of cancer and in neurodegenerative and demyelinating diseases including multiple sclerosis. Further, anti-KLK6 antibodies attenuated disease manifestations in the mouse model of multiple sclerosis. Availability of specific antibodies against KLK6 is fundamental to the development of improved diagnostic and/or immunotherapeutic applications. Here, we exploited the enhanced immunogenicity of mammalian proteins in avian species to generate a polyclonal antibody against KLK6.

Results

Chicken were immunized with recombinant KLK6 and antibodies Y (IgYs) were purified from egg yolk with a simple procedure and evaluated for KLK6 detection by ELISA and Western blot using recombinant proteins and human cell lysates and supernatants. The anti-KLK6 Y polyclonal exhibited high affinity for KLK6 with a detection limit of 30 fmol. On the other hand, the widely used rabbit polyclonal antibody that was raised against the same recombinant KLK6 had a detection limit of 300 fmol. Moreover, the IgYs did not display any crossreactivity with recombinant KLKs or endogenous KLKs and other cellular proteins.

Conclusions

Based on its high specificity and sensitivity the developed anti-KLK6 IgY is expected to aid the development of improved diagnostic tools for the detection of KLK6 in biological and clinical samples.

Phospholipase Cζ rescues failed oocyte activation in a prototype of male factor infertility

Objective

To determine the effect of infertility-linked sperm phospholipase Cζ (PLCζ) mutations on their ability to trigger oocyte Ca²⁺ oscillations and development, and also to evaluate the potential therapeutic utility of wild-type, recombinant PLCζ protein for rescuing failed oocyte activation and embryo development.

Design

Test of a novel therapeutic approach to male factor infertility.

Setting

University medical school research laboratory.

Patient(s)

Donated unfertilized human oocytes from follicle reduction.

Intervention(s)

Microinjection of oocytes with recombinant human PLCζ protein or PLCζ cRNA and a Ca²⁺-sensitive fluorescent dye.

Main Outcome Measure(s)

Measurement of the efficacy of mutant and wild-type PLCζ-mediated enzyme activity, oocyte Ca²⁺ oscillations, activation, and early embryo development.

Result(s)

In contrast to the wild-type protein, mutant forms of human sperm PLCζ display aberrant enzyme activity and a total failure to activate unfertilized oocytes. Subsequent microinjection of recombinant human PLCζ protein reliably triggers the characteristic pattern of cytoplasmic Ca²⁺ oscillations at fertilization, which are required for normal oocyte activation and successful embryo development to the blastocyst stage.

Conclusion(s)

Dysfunctional sperm PLCζ cannot trigger oocyte activation and results in male factor infertility, so a potential therapeutic approach is oocyte microinjection of active, wild-type PLCζ protein. We have demonstrated that recombinant human PLCζ can phenotypically rescue failed activation in oocytes that express dysfunctional PLCζ, and that this intervention culminates in efficient blastocyst formation.

Prothymosin alpha: a ubiquitous polypeptide with potential use in cancer diagnosis and therapy

The thymus is a central lymphoid organ with crucial role in generating T cells and maintaining homeostasis of the immune system. More than 30 peptides, initially referred to as "thymic hormones," are produced by this gland. Although the majority of them have not been proven to be thymus-specific, thymic peptides comprise an effective group of regulators, mediating important immune functions. Thymosin fraction five (TFV) was the first thymic extract shown to stimulate lymphocyte proliferation and differentiation. Subsequent fractionation of TFV led to the isolation and characterization of a series of immunoactive peptides/polypeptides, members of the thymosin family. Extensive research on prothymosin α (proTα) and thymosin α1 (Tα1) showed that they are of clinical significance and potential medical use. They may serve as molecular markers for cancer prognosis and/or as therapeutic agents for treating immunodeficiencies, autoimmune diseases and malignancies. Although the molecular mechanisms underlying their effect are yet not fully elucidated, proTα and Tα1 could be considered as candidates for cancer immunotherapy. In this review, we will focus in principle on the eventual clinical utility of proTα, both as a tumor biomarker and in triggering anticancer immune responses. Considering the experience acquired via the use of Tα1 to treat cancer patients, we will also discuss potential approaches for the future introduction of proTα into the clinical setting.

Structural modifications of ⁹⁹mTc-labelled bombesin-like peptides for optimizing pharmacokinetics in prostate tumor targeting

PURPOSE

The main goal of the present study was to investigate the importance of the addition of a positively charged aa in the naturally occurring bombesin (BN) peptide for its utilization as radiodiagnostic agent, taking into consideration the biodistribution profile, the pharmacokinetic characteristics and the tumor targeting ability.

METHODS

Two BN-derivatives of the general structure [M-chelator]-(spacer)-BN(2-14)-NH(2), where M: (99m)Tc or (185/187)Re, chelator: Gly-Gly-Cys-, spacer: -(arginine)(3)-, M-BN-A; spacer: -(ornithine)(3)-, M-BN-O; have been prepared and evaluated as tumor imaging agents.

RESULTS

The peptides under study presented high radiolabelling efficiency (>98%), significant stability in human plasma (>60% intact radiolabelled peptide after 1h incubation) and comparable receptor binding affinity with the standard [(125)I-Tyr(4)]-BN. Their internalization rates in the prostate cancer PC-3 cells differed, although the amount of internalized peptide was the same. The biodistribution and the dynamic γ-camera imaging studies in normal and PC-3 tumor-bearing SCID mice have shown significant tumor uptake, combined with fast blood clearance, through the urinary pathway.

CONCLUSION

The addition of the charged aa spacer in the BN structure was advantageous for biodistribution, pharmacokinetics and tumor targeting ability, because it reduced the upper abdominal radioactivity levels and increased tumor/normal tissue contrast ratios.

Spacer site modifications for the improvement of the in vitro and in vivo binding properties of (99m)Tc-N(3)S-X-bombesin[2-14] derivatives

It has been shown that gastrin releasing peptide receptors (GRPRs) are overexpressed in various types of cancer cells. Bombesin is an analogue of the mammalian GRP that binds with high specificity and affinity to GRPRs. Significant research efforts have been lately devoted to the design of radiolabeled 8 or 14 aminoacid bombesin (BN) peptides for the detection (either with gamma or positron emitting radionuclides) and therapy (with beta(-) emitting radionuclides) of cancer. The specific aim of the present study was to further investigate the radiolabeled peptide structure and to determine whether the total absence of a linker or the use of a basic diverse amino acid linker could influence the biodistribution profile of the new compounds for specific targeting of human prostate cancer. Thus, two new derivatives with the structure Gly-Gly-Cys-X-BN[2-14], where linker X is either zero (I) or Orn-Orn-Orn (Orn: ornithine) (II) were designed and synthesized. The corresponding (99m)Tc-BN derivatives were obtained with high radiochemical yield (>98%) and had almost identical retention times in RP-HPLC with the (185/187)Re complexes, which were also characterized by ESI-MS. Metabolic stability was found to be high in human plasma, moderate in PC-3 cells, and rather low in mouse liver and kidney homogenates for both BN derivatives studied. The BN derivative without the spacer was less stable in cell culture and liver homogenates. A satisfactory binding affinity to GRPRs, in the nanomolar range, was obtained for both BN derivatives as well as for their Re complexes, with BN (II) demonstrating the highest one. In vitro internalization/externalization assays indicated that approximately 6% of BN (I) and approximately 25% of BN (II) were internalized into PC-3 cells. In vivo evaluation in normal Swiss mice and in tumor bearing SCID mice showed that BN (II) presented higher tumor and pancreas uptake than BN (I). Small animal SPECT dynamic imaging, carried out after an injection of BN (II) in mice bearing PC-3 tumors, resulted in PC-3 tumor delineation with low background activity. Overall, this study performed for two new N(3)S-X-BN[2-14] derivatives indicated that hydrophilicity and charge strongly affected the in vitro and in vivo binding properties and the biodistribution pattern. This finding is confirmed by SPECT imaging of BN (II), which is under further in vivo evaluation for detecting cancer-positive GRPRs.

In vitro binding and in vivo biodistribution studies of the neuroprotective peptide humanin using [125I]humanin derivatives

Humanin (HN) and HN-derivatives are a family of peptides first reported in the last decade with potent in vitro and in vivo neuroprotective activity, which is mediated through a not completely elucidated mechanism. Recently, our group has evaluated the effect of various HN-derivatives on the 3-quinuclidinyl benzilate (QNB)-induced impairment of spatial orientation and memory in rats, by employing the T-maze test. In the present work four new, tyrosine containing HN-derivatives were synthesized (Y-PAGASRLLLTGEIDLP, peptide I; Y-PAGASRLLLLTGEIDLP, peptide II; Y-SALLRSIPAPAGASRLLLTGEIDLP, peptide III; Y-SALLRSIPAPAGASRLLLLTGEIDLP, peptide IV). The neuroprotective action of these peptides was evaluated in the T-maze test and the most active among them (peptides I and III) was radiolabeled with (125)I. The pure monoradioiodinated peptides were used in: (i) in vitro binding studies with various neuronal cell lines and with brain and stomach membranes from rats and mice and (ii) in vivo biodistribution studies in rats and mice. Moreover, the metabolic stability of the above radiolabeled peptides was studied. Under the experimental conditions used, our data do not confirm the existence of specific binding sites for HN on the neuronal tissue. Nevertheless, they are setting the basis for further relevant studies aiming at the clarification of the mode of the neuroprotective action of HN-peptides.

Solid-phase synthesis of a biotin derivative and its application to the development of anti-biotin antibodies

A biotin derivative, namely biotin-aminocaproic acid-lysine (BAL), was synthesized with solid-phase chemistry, conjugated to a carrier-protein, and used for rabbit immunization. The aminocaproic acid-lysine "long-arm" was used in order to project the biotin-hapten above the carrier-protein surface. Lysine was selected due to its N(epsilon)-amino group, through which BAL was conjugated to the carrier-protein. BAL was synthesized on a commercially available resin with the Fmoc-solid-phase strategy; this has simplified the experimental procedure, overcome the need for intermediate purification steps, and led to a final product of high purity, with high yield. The anti-BAL antibodies recognized free biotin, as shown with an in-house-developed ELISA, in which biotin conjugated to a synthetic "lysine-dendrimer" was used to coat the ELISA microwells. In immunocytology and Western-blot experiments, the anti-BAL antibodies led to similar results with those obtained with streptavidin. Synthetic derivatives of hapten molecules that can be easily prepared with solid-phase chemistry, such as BAL, may be used for the development of specific antibodies for the corresponding hapten.

Synthesis and characterization of rhenium and technetium-99m tricarbonyl complexes bearing the 4-[3-bromophenyl]quinazoline moiety as a biomarker for EGFR-TK imaging

Aiming at the development of technetium-99m ((99m)Tc) complexes for early detection and staging of EGFR positive tumors, the tyrosine kinase inhibitor 6-amino-4-[(3-bromophenyl)amino]quinazoline was derivatized with pyridine-2-carboxaldehyde to generate the imine 6-(pyridine-2-methylimine)-4-[(3-bromophenyl)amino]quinazoline suitable for reacting with the fac-[(99m)Tc(CO)(3)](+) core as an N,N bidentate ligand. The labelling was performed in high yield (>90%) by ligand exchange reaction using fac-[(99m)Tc(OH(2))(3)(CO)(3)](+) as precursor. The (99m)Tc complex was characterized by comparative HPLC analysis using the analogous rhenium (Re) complex as reference. The Re complex was prepared by ligand exchange reaction using the fac-[ReBr(3)(CO)(3)](2-) as precursor and was fully characterized by NMR and IR spectroscopies and elemental analysis. In vitro studies indicate that both the ligand and its Re complex inhibit the EGFR autophosphorylation (IC(50): 17+/-3.7 and 114+/-23 nM respectively) in intact A431 cells, bind the receptor in a reversible mode, and inhibit A431 cell growth (IC(50): 5.2+/-1.1 and 2.0+/-0.98 microM respectively). Biodistribution of the (99m)Tc complex in healthy animals showed a rather fast blood and soft tissue clearance between 1 and 15 min p.i. with excretion occurring mainly via the hepatobiliary system.

Immunological potential of Helix vulgaris and Rapana venosa hemocyanins

A new hemocyanin was isolated from the hemolymph of garden snails Helix vulgaris, composed of two isoforms, HvH1 and HvH2 separated on an ion exchange column DEAE-Sepharose 6CL. Structural and immunological properties of Helix vulgaris hemocyanin were studied in comparison with molluscan Hcs Rapana venosa and Megathura crenulata. The possibility of using HvH and RvH as carriers of small molecules (haptens) in immunizing protocols was studied in comparison with KLH, which is a widely used, highly immunogenic carrier protein. By using HvH as a carrier of the well-known hapten TNBS (2,4,6-trinitrobenzene sulfonic acid), an increasing with time production of hapten-specific TFN-gamma was detected in splenocyte cultures of mice, which lasted longer than in case of KLH and RvH carriers. Also, use of HvH or RvH as a carrier of the hapten ProT alpha[101-109] (i.e., the synthetic C-terminal fragment of the poorly immunogenic protein prothymosin alpha) showed that antisera of higher titres than that of the control conjugate (ProT alpha[101-109]-KLH) were obtained immediately after the second bleeding. HvH and RvH may prove to be useful for the development of new antiviral, antibacterial and antitumor vaccines, since they seem to launch strong and specific immune response against the conjugated antigens.

The multiple T-maze in vivo testing of the neuroprotective effect of humanin analogues

Humanin (HN) and its analogues have been shown to protect cells against death induced by various Alzheimer's disease (AD) genes and amyloid-beta-peptides in vitro; the analogues [Gly(14)]-HN and colivelin have also been shown to be potent in reversing learning and memory impairment induced by scopolamine or quinuclidinyl benzilate (QNB) in mice or rats in vivo using the Y-maze or multiple T-maze tests. This paper describes the activity of new peptides of the HN family, after i.p. administration, on QNB-induced impairment of spatial memory in the multiple T-maze test in rats. The following peptides have been studied: HN analogues truncated either on the C- or N-terminus, or analogues having a tert-Leu in place of Leu in the central part of the molecule, the active HN core PAGASRLLLLTGEIDLP (RG-PAGA) and its analogues having three or five leucines instead of four, and finally the recently described hybrid peptide colivelin (i.e. a peptide having the activity-dependent neurotrophic factor SALLRSIPA attached to the N-terminus of the active RG-PAGA) and its des-Leu- and plus-Leu-analogues. While the truncated analogues and most of the tert-Leu containing analogues were devoid of activity, the analogues of the RG-PAGA were active, i.e. they reversed the impairment of spatial memory irrespective of the number of Leu present in their sequence. The highest activity was shown by colivelin and its des-Leu-analogue. These results demonstrate the potential of HN analogues in the modulation of the cholinergic system, which plays an important role in the cognitive deficits associated with AD and other neurodegenerative diseases.

Immunocytological and preliminary immunohistochemical studies of prothymosin alpha, a human cancer-associated polypeptide, with a well-characterized polyclonal antibody

Prothymosin alpha (ProTalpha) is a nuclear polypeptide of great biological and, possibly clinical, importance, because its expression levels have been associated with early diagnosis/prognosis of human cancer. It is therefore interesting to raise easily available and cost-effective antibodies that would be applied to develop reliable ProTalpha immunodiagnostics. In this study, New Zealand white rabbits and laying hens were parallel immunized against intact ProTalpha or the synthetic fragments ProTalpha[1-28], ProTalpha[87-109], and ProTalpha[101-109], all conjugated to keyhole limpet hemocyanin (KLH). The corresponding antibodies G and Y were immunochemically evaluated in parallel with ELISA and Western blot systems and applied to fluorescence immunocytology experiments using various cancer cell lines and normal cells. The antibody G raised against ProTalpha[101-109]/KLH had excellent functional characteristics in the Western blot and immunocytology experiments, where the fluorescent signal was almost exclusively shown in the cell nucleus independently of the cells assayed. The above antibody has been applied to preliminary IHC staining of human cancer prostate tissues, leading to a high percentage of clearly and intensively stained nuclei in the adenocarcinoma tissue; this antibody can be further used in cancer tissue immunostaining and in research concerning the role of ProTalpha in tumorigenesis.

Solid-phase Synthesis of a Peptide Derivative of Thymosin alpha1 and Initial Studies on its99mTc-Radiolabelling

A derivative (1) of the immunopotentiating 28-peptide thymosin alpha1 has been especially designed, so that it can be (99m)Tc-radiolabelled, and synthesized following the Fmoc solid-phase peptide synthesis approach. Derivative 1 contains the N-terminal fragment Talpha1[1-14] as a bioactive segment, at the C-terminus of which a (99m)Tc-chelating moiety consisting of N(alpha),N(alpha)-dimethylglycine, serine and cysteine is linked through the N(epsilon)-amino group of a 'bifunctional' lysine residue; the latter is indirectly anchored on the solid-phase peptide synthesis resin through 6-aminocaproic acid (dmGSCK{N(epsilon)-Talpha1[1-14]}Aca). Synthetic derivative 1 was obtained at high overall yield (approximately 35%) and purity (>95%) and shown to be efficiently radiolabelled with (99m)Tc, thus resulting in the first, to our knowledge, so far reported (99m)Tc-radiolabelled derivative of thymosin alpha1, which may be eventually used as a specific molecular tool for the in vitro/in vivo study of the mode of action of the parent bioactive peptide.

Determination of natural olive fruit fly pheromone in insect samples by enzyme linked immunoassays

The olive fruit fly pheromone avidin-biotin ELISA immunoassay, based on the use of polyclonal G antibodies derived from rabbits (reported previously) and a newer assay, based on the use of polyclonal Y antibodies isolated from the eggs of laying hens (reported in this paper), were applied successfully for the analysis of natural pheromone in virgin adult female olive fruit flies. According to the results obtained, the pheromone content in the glands of adult female olive fruit flies increases from the third to the ninth day of their age. During the calling period, the female olive fruit flies seem to emit approximately 1.1microg pheromone/insect/day at least. The immunoassay, based on the Y antibodies, is slightly more sensitive (detection limit 40ng/mL) than the assay based on polyclonal anti-pheromone rabbit antiserum (detection limit 80ng/mL). As revealed by thorough cross-reactivity studies, including 14 structurally similar to the olive fruit fly pheromone molecules, the newer immunoassay is less selective than the previous one and seems to cross react with few molecules bearing the spiroketal moiety.

The immunologically active site of prothymosin alpha is located at the carboxy-terminus of the polypeptide. Evaluation of its in vitro effects in cancer patients

Prothymosin alpha (proTalpha) is a 109 amino acid long polypeptide presenting distinct immunoenhancing activity in vitro and in vivo. Recent reports suggest that in apoptotic cells, proTalpha is cleaved by caspases at its carboxy(C)-terminus generating potentially bioactive fragments. In this study, we identified the peptide segment of proTalpha presenting maximum immunomodulatory activity. Calf thymus proTalpha was trypsinised, and the five fragments produced (spanning residues 1-14, 21-30, 31-87, 89-102 and 103-109) were tested for their ability to stimulate healthy donor- and cancer patient-derived peripheral blood mononuclear cell (PBMC) proliferation in autologous mixed lymphocyte reaction (AMLR), natural killer and lymphokine-activated killer cell activity, intracellular production of perforin, upregulation of adhesion molecules and CD25 expression. ProTalpha(89-102) and proTalpha(103-109) significantly fortified healthy donor-lymphocytes' immune responses to levels comparable to those induced by intact proTalpha. These effects were more pronounced in cancer patients, where peptides proTalpha(89-102) and proTalpha(103-109) partly, however significantly, restored the depressed AMLR and cytolytic ability of PBMC, by simulating the biological activity exerted by intact proTalpha. ProTalpha(1-14), proTalpha(21-30) and proTalpha(31-87) marginally upregulated lymphocyte activation. This is the first report showing that proTalpha's immunomodulating activity can be substituted by its C-terminal peptide(s). Whether generation and externalization of such immunoactive proTalpha fragments occurs in vivo, needs further investigation. However, if these peptides can trigger immune responses, they may eventually be used therapeutically to improve some PBMC functions of cancer patients.

Solution structure of Ser14Gly-humanin, a potent rescue factor against neuronal cell death in Alzheimer's disease

The NMR solution study of Ser14Gly-humanin (S14G-HN), a 1000-fold more potent derivative of humanin (HN), is reported. HN is 24-residue peptide that selectively suppresses neuronal cell death caused by Alzheimer's disease (AD)-specific insults and offers hope for the development of a cure against AD. In aqueous solution the NMR data show that S14G-HN is a flexible peptide with turn-like structures in its conformational ensemble distributed over an extensive part of its sequence from Pro3 to Glu15. In the more lipophilic environment of 30% TFE, an alpha-helical structure spanning residues Phe6 to Thr13 is identified. Comparison of these findings to the NMR structure of the parent HN and to existing structure-function relationship literature data outlines the important for activity structural features for this class of neuroprotective peptides, and brings forth flexibility as an important characteristic that may facilitate interactions with functional counterparts of the neuroprotection pathway.

Synthesis, Characterization, and Biological Evaluation of M(I)(CO)3(NNO) Complexes (M = Re, 99mTc) Conjugated to 2-(4-Aminophenyl)benzothiazole as Potential Breast Cancer Radiopharmaceuticals

The synthesis and biological evaluation of new M(I)(CO)3(NNO) (M = Re, 99mTc) complexes attached to the antitumor agent 2-(4-aminophenyl)benzothiazole are reported. The fluorescent rhenium complex enters MCF-7 breast cancer cells but does not enter normal HFFF-2 and MRC-5 cells. The analogous radioactive 99mTc complex produces fast blood and soft tissue clearance when administered to healthy mice. These complexes are promising candidates for developing radiopharmaceuticals for imaging (99mTc) and targeted radiotherapy (186Re, 188Re) of breast cancer.

Development and immunochemical evaluation of antibodies Y for the poorly immunogenic polypeptide prothymosin alpha

Since conserved mammalian polypeptides are believed to exhibit enhanced immunogenicity in avian species, hens were immunized against the poorly immunogenic, highly conserved mammalian polypeptide prothymosin alpha (ProTalpha), i.e. against either non-conjugated ProTalpha (isolated from bovine thymus) or ProTalpha conjugated to keyhole limpet hemocyanin (ProTalpha/KLH). The antibodies Y were isolated from the egg yolk and evaluated through suitable dot-blot and ELISA systems in parallel with antibodies G isolated from the antiserum of rabbits immunized against the same immunogens. As revealed, antibodies Y and G of low titer and/or affinity were obtained against non-conjugated ProTalpha, while antibodies Y against ProTalpha/KLH had a better apparent titer, could better discriminate between ProTalpha and the closely related bioactive peptide thymosin alpha 1, and were obtained at much larger quantities than the corresponding antibodies G.

Solution structure of humanin, a peptide against Alzheimer's disease-related neurotoxicity

Humanin is a newly identified 24-residue peptide that suppresses neuronal cell death caused by a wide spectrum of familial Alzheimer's disease genes and the beta-amyloid peptide. In this study, NMR and circular dichroism studies of synthetic humanin in aqueous and 30% 2,2,2-trifluoroethanol (TFE) solutions are reported. In aqueous solution, humanin exists predominantly in an unstructured conformation in equilibrium with turn-like structures involving residues Gly5 to Leu10 and Glu15 to Leu18, providing indication of nascent helix. In the less polar environment of 30% TFE, humanin readily adopts helical structure with long-range order spanning residues Gly5 to Leu18. Comparative 3D modeling studies and topology predictions are in qualitative agreement with the experimental findings in both environments. Our studies reveal a flexible peptide in aqueous environment, which is free to interact with possible receptors that mediate its action, but may also acquire a helical conformation necessary for specific interactions and/or passage through membranes.

High-yield, solid-phase synthesis of humanin, an Alzheimer's disease associated, novel 24-mer peptide which contains a difficult sequence

Humanin is a novel, 24-mer residue bioactive peptide, which antagonizes Alzheimer's disease (AD) related neurotoxicity and offers a hope for developing new therapeutics against AD. Access to adequate amounts of pure humanin is a prerequisite for further, thorough, investigation of the pharmacological properties and therapeutic potency of the peptide. Until now, humanin has been obtained mainly by molecular biology techniques. In this work the Fmoc solid-phase synthesis of humanin on an in-house prepared 2-Cl-tritylamidomethyl polystyrene resin is described fully. Special precautions, i.e. prolonged deprotection steps, should be taken to achieve a high overall yield, since humanin seems to contain a 'difficult sequence' (R4G5F6S7C8L9) near its highly lipophilic, biologically important region L9L10L11L12.

Synthesis of haptens and development of an immunoassay for the olive fruit fly pheromone

An enzyme-linked immunosorbent assay (ELISA) for the olive fruit fly pheromone, Bactrocera oleae Gmelin, was developed. The assay uses polyclonal antibodies, raised in rabbits, against (+/-)-beta-[3-(1,7-dioxaspiro[5.5]undecane)]propionic acid, 2 (hapten I), conjugated to the KLH (keyhole limpet hemocyanin) by the carbodiimide method. A second hapten, (+/-)-delta-[3-(1,7-dioxaspiro[5.5]undecane)]butylamine, 3 (hapten II), after conjugation to a biotin moiety, was used for indirect immobilization onto ELISA microwells precoated with the glycoprotein avidin. The developed ELISA method measures the synthetic olive fruit fly pheromone in concentrations ranging between 0.08 and 10 microg/mL and shows great promise for practical applications for pheromone detection in environmental and biological samples. The results obtained strongly indicate that this technique, to our knowledge the first insect pheromone enzyme-linked immunosorbent assay so far reported, is a fast, sensitive, inexpensive, and highly convenient method for the analysis of a volatile and low molecular weight compound such as 1,7-dioxaspiro[5.5]undecane, 1.

Comparative evaluation of four trityl-type amidomethyl polystyrene resins in Fmoc solid phase peptide synthesis

Four trityl-type (i.e. non-substituted trityl-, o-Cl-trityl-, o-F-trityl- and p-CN-trityl-) amidomethyl polystyrene resins were evaluated comparatively, in terms of the stability of the trityl-ester bond in slightly acidic dichloromethane solutions, and the p-CN-trityl-amidomethyl polystyrene resin was found to be the most stable of them. The above resins were applied, in parallel with Wang benzyl-type resin, well known for its stability in mild acidic conditions, to the Fmoc solid phase synthesis of the 43-amino acid residue long bioactive peptide thymosin beta-4. Independent of their differences in acid sensitivity, the resins seemed to function equally well under the conditions used, since pure thymosin beta-4 was obtained with a final yield of approximately 30% from each resin. The trityl-type amidomethyl polystyrene resins were also applied, in parallel with the Wang resin, to the Fmoc solid phase synthesis of a bioactive peptide containing proline at its C-terminus, i.e. the N-terminal tetrapeptide of thymosin beta-4, AcSDKP. In this case, the best yield (87%) was obtained with the o-Cl-trityl-amidomethyl polystyrene resin, which may be the resin of choice, of those studied, for the Fmoc solid phase peptide synthesis.

Effect of copolymer composition on the physicochemical characteristics, in vitro stability, and biodistribution of PLGA-mPEG nanoparticles

The physicochemical properties, the colloidal stability in vitro and the biodistribution properties in mice of different PLGA-mPEG nanoparticle compositions were investigated. The nanoparticles were prepared by a precipitation-solvent evaporation technique. The physical characteristics and the colloidal stability of the PLGA-mPEG nanoparticles were significantly influenced by the composition of the PLGA-mPEG copolymer used to prepare the nanoparticles. PLGA-mPEG nanoparticles prepared from copolymers having relatively high mPEG/PLGA ratios were smaller and less stable than those prepared from copolymers having relatively low mPEG/PLGA ratios. All PLGA-mPEG nanoparticle compositions exhibited prolonged residence in blood, compared to the conventional PLGA nanoparticles. The composition of the PLGA-mPEG copolymer affected significantly the blood residence time and the biodistribution of the PLGA-mPEG nanoparticles in liver, spleen and bones. The in vivo behavior of the different PLGA-mPEG nanoparticle compositions did not appear to correlate with their in vitro stability. Optimum mPEG/PLGA ratios appeared to exist leading to long blood circulation times of the PLGA-mPEG nanoparticles. This may be associated with the effects of the mPEG/PLGA ratio on the density of PEG on the surface of the nanoparticles and on the size of the nanoparticles.

Lymphocytes from bipolar and schizophrenic patients share common biochemical markers related to histone synthesis and histone cell membrane localization characteristic of an activated state

In a previous communication, based on the total histone and histone variants' synthesis rates, biochemical parameters used for the characterization of the activation state of lymphocytes, we showed that a portion of the lymphocyte population obtained from peripheral blood of patients with bipolar disorder in the manic and/or depressed phases of the illness were in an activated state as opposed to normothymic patients and control subjects whose lymphocytes are in a resting, Go, state. In light of these previous findings, in the present investigation, we have analyzed total histone synthesis rates and the H2A and H3 histone variants' synthesis pattern of acid-extracted histones from the lymphocytes' nuclear fraction obtained from control subjects, patients with bipolar disorder in all phases of the illness, and patients with schizophrenia. Additional biochemical parameters, such as total cellular protein and DNA synthesis rates, were also studied. Moreover, recent findings from other investigators showed the association of histones on the plasma membrane fraction of PHA-activated, but not Go resting lymphocytes. Based on these results, acid-extracted proteins from the plasma membrane fraction obtained from control, bipolar patients in all phases of the illness, and schizophrenic patients were analyzed by immunoblotting using a polyclonal histone antibody, anti-H2B. All biochemical parameters tested show that a portion of the lymphocyte population from bipolar, i.e. manic and depressive, as well as schizophrenic patients are in an activated state and clearly indicate that the unusual for lymphocytes cell cycle-related histone biochemical properties are common to both disorders.

Synthesis and angiogenetic activity in the chick chorioallantoic membrane model of thymosin beta-15

Thymosin beta-15 (Tbeta15), a 44 amino acid peptide (MW = 5173) localized in human prostate and breast cancer tissues was successfully synthesized in multigram quantities using Fmoc solid-phase peptide synthesis. The synthesized product was shown to have the right structure by ESI and MALDI mass spectral techniques and amino acid analysis. Relatively high yield was achieved, which might be due to enhanced acid stability of the p-cyanotrityl resin used. The effect of the synthesized Tbeta15 on the angiogenesis process was investigated using the chick chorioallantoic membrane (CAM) in vivo model. At concentrations above 1 microg/10 microl per disc, Tbeta15 exhibited a positive effect on angiogenesis, comparable to the effect of the intense angiogenetic factor phorbol 12-myristate 13-acetate at a standard concentration of 0.1 microg/10 microl per disc. The results of this study contribute to the further elucidation of the biological regulatory role of thymosin peptides and provide helpful information in the investigation of their possible therapeutic potential.

Effect of thymosin peptides on the chick chorioallantoic membrane angiogenesis model

The effect of alpha- and beta-thymosin peptides, namely prothymosin alpha (ProT(alpha)), thymosin alpha(1) (T(alpha)1), parathymosin alpha (ParaT(alpha)), thymosin beta(4) (Tbeta4), thymosin beta(10) (Tbeta10), and thymosin beta(9) (Tbeta9), on the angiogenesis process was investigated using the chick chorioallantoic membrane as an in vivo angiogenesis model. The thymosin peptides tested were applied in 10 microl aliquots containing 0.01-4 nmoles of Tbeta4, Tbeta10 or Tbeta9, 0.016-6.66 nmoles of T(alpha)1, 4.1 pmoles-1.66 nmoles of ProT(alpha), and 4.4 pmoles-1.76 nmoles of ParaT(alpha). Phorbol 12-myristate 13-acetate and hydrocortisone were also used as positive and negative control, respectively. Tbeta4, ProT(alpha) and T(alpha)1 were found to enhance angiogenesis, while Tbeta10, Tbeta9 and ParaT(alpha) exhibited an inhibitory effect on the angiogenesis process. When mixtures of Tbeta4 and Tbeta10 containing active amounts of the two peptides at different proportions were applied, the promoting effect of Tbeta4 on angiogenesis was reversed in the presence of increasing concentrations of Tbeta10 and vice versa. The effect of Tbeta10, Tbeta9, ProT(alpha) and ParaT(alpha), in parallel with Tbeta4 and T(alpha)1, on the angiogenesis process was investigated for the first time as far as we know and the results of this study offer more insight into the biological regulatory roles of thymosin peptides, and provide helpful information about their therapeutic potential. Whether these agents could be used either as inhibitors of angiogenesis in disease states where uncontrolled angiogenesis is involved, e.g. in carcinogenesis, or as angiogenesis promoters that could be useful in wound healing, fracture repair, peptic ulcers etc., remains to be further studied.

Effect of dose on the biodistribution and pharmacokinetics of PLGA and PLGA-mPEG nanoparticles

The effect of nanoparticle dose on the biodistribution and pharmacokinetics of conventional PLGA and stealth poly(Lactide-co-glycolide)-monomethoxypoly(ethyleneglycol) (PLGA-mPEG) nanoparticles was investigated. The precipitation-solvent diffusion method was used to prepare PLGA and PLGA-mPEG nanoparticles labeled with 125I-cholesterylaniline. These were administered intravenously (i.v.) in mice and at predetermined time intervals the animals were sacrificed and their tissues were excised and assayed for radioactivity. Within the dose range applied in this study, blood clearance and mononuclear phagocyte system (MPS) uptake of the PLGA nanoparticles depended on dose whereas they were independent of dose in the case of the PLGA-mPEG nanoparticles. Increasing the dose, decreased the rates of blood clearance and MPS uptake of the PLGA nanoparticles, indicating a certain degree of MPS saturation at higher doses of PLGA nanoparticles. The dose affected the distribution of PLGA nanoparticles between blood and MPS (liver) but it did not affect the nanoparticle levels in the other tissues. Within the range of doses applied here, the PLGA nanoparticles followed non-linear and dose-dependent pharmacokinetics whereas the PLGA-mPEG nanoparticles followed linear and dose-independent pharmacokinetics. In addition to the prolonged blood residence, the dosage-independence of the pharmacokinetics of the PLGA-mPEG nanoparticles would provide further advantages for their application in controlled drug delivery and in drug targeting.