Effect of peptide length on the conjugation to the gold nanoparticle surface: a molecular dynamic study

Background

Gold nanoparticles now command a great deal of attention for medical applications. Despite the importance of nano-bio interfaces, interaction between peptides and proteins with gold surfaces is not still fully understood, especially in a molecular level.

Methods

In the present study computational simulation of adsorption of 20 amino acids, in three forms of mono-amino acid, homo di-peptide and homo tri-peptide, on the gold nanoparticles was performed by Gromacs using OPLSAA force field. The flexibility, stability, and size effect of the peptides on the gold nanoparticles were studied as well as the molecular structure of them.

Results

According to our results, adsorbed homo tri-peptides on the gold surface had more flexibility, more gyration, and the farthest distance from the GNP in comparison with homo di-peptides and mono-amino acids.

Conclusion

Our findings provide new insights into the precise control of interactions between amino acids anchored on the GNPs.

     

An Efficient and Rapid Method to Monitor the Oxidative Degradation of Protein Pharmaceuticals: Probing Tyrosine Oxidation with Fluorogenic Derivatization

Purpose

The loss of potency of protein therapeutics can be linked to the oxidation of specific amino acid residues leading to a great variety of oxidative modifications. The comprehensive identification of these oxidative modifications requires high-resolution mass spectrometry analysis, which requires time and expensive resources. Here, we propose a fluorogenic derivatization method of oxidized Tyr and Phe yielding benzoxazole derivatives, as an orthogonal technique for the rapid screening of protein oxidation.

Methods

Four model proteins, IgG1, human growth hormone (hGH), insulin and bovine serum albumin (BSA) were exposed to oxidation via peroxyl radicals and metal-catalyzed reactions and efficiently screened by fluorogenic derivatization of Tyr and Phe oxidation products. Complementary LC-MS analysis was done to identify the extent of methionine oxidation in oxidized proteins.

Results

The Fluorogenic derivatization technique can easily be adapted to a 96-well plate, in which several protein formulations can be screened in short time. Representatively for hGH, we show that the formation of benzoxazole parallels the oxidation of Met to methionine sulfoxide which enables estimation of Met oxidation by just recording the fluorescence.

Conclusions

Our rapid fluorescence based screening allows for the fast comparison of the stability of multiple formulations.

     

PEGylation of a High-Affinity Anti-(+)Methamphetamine Single Chain Antibody Fragment Extends Functional Half-Life by Reducing Clearance

Purpose

Methamphetamine (METH) abuse is a worldwide drug problem, yet no FDA-approved pharmacological treatments are available for METH abuse. Therefore, we produced an anti-METH single chain antibody fragment (scFv7F9Cys) as a pharmacological treatment for METH abuse. ScFv’s have a short half-life due to their small size, limiting their clinical use. Thus, we examined the pharmacokinetic effects of conjugating poly(ethylene) glycol (-PEG) to scFv7F9Cys to extend its functional half-life.

Methods

The affinity of scFv7F9Cys and PEG conjugates to METH was determined in vitro via equilibrium dialysis saturation binding. Pharmacokinetic and parameters of scFv7F9Cys and scFv7F9Cys-PEG20K (30 mg/kg i.v. each) and their ability to bind METH in vivo were determined in male Sprague-Dawley rats receiving a subcutaneous infusion of METH (3.2 mg/kg/day).

Results

Of three PEGylated conjugates, scFv7F9Cys-PEG20K was determined the most viable therapeutic candidate. PEGylation of scFv7F9Cys did not alter METH binding functionality in vitro, and produced a 27-fold increase in the in vivo half-life of the antibody fragment. Furthermore, total METH serum concentrations increased following scFv7F9Cys or scFv7F9Cys-PEG20K administration, with scFv7F9Cys-PEG20K producing significantly longer changes in METH distribution than scFv7F9Cys.

Conclusions

PEGylation of scFv7F9Cys significantly increase the functional half-life of scFv7F9Cys, suggesting it may be a long-lasting pharmacological treatment option for METH abuse.

     

The Preservation of Lyophilized Human Growth Hormone Activity: how Do Buffers and Sugars Interact?

Purpose

One of the most common classes of excipients used in protein formulations are buffers. The aim of this work is to investigate the effect of buffers on protein stabilization given by sugars during freeze drying.

Methods

Molecular Dynamics simulations of human growth hormone (hGH) in the presence of sucrose and trehalose were performed, and the impact of phosphate and citrate buffers on their protective action was analyzed.

Results

We found that buffers broke the hydrogen bonding network formed by excipients, and the consequences of this disruption of structure ordering were different in sucrose-based or trehalose-based formulations. More specifically, we observed that buffers increased protein recovery in the presence of excipients, such as sucrose, that exert their action mainly by preferential exclusion. By contrast, the opposite effect was sometimes noted in the case of excipients, such as trehalose, whose protective action is related to the formation of a highly structured matrix.

Conclusions

We found that buffers have important properties, other than the control of pH, that can contribute to the overall stability of proteins. Some of these properties are related to their interaction with the other components of the formulation.

     

Photo-oxidation of IgG1 and Model Peptides: Detection and Analysis of Triply Oxidized His and Trp Side Chain Cleavage Products

Purpose

Triply oxidized histidine in an IgG1 monoclonal antibody was noticed when exposed to ICH light conditions. In order to understand the role of light source, irradiation wavelengths and primary sequence, specifically those of a nearby tryptophan, we synthesized and exposed several peptides to ICH light conditions and analyzed the products using LC-MS analysis.

Methods

Protein and peptide samples were photo-irradiated under ICH conditions as well as with monochromatic light at λ?=?254 nm and analyzed using either LTQ Orbitrap or a LTQ-FT ion cyclotron resonance mass spectrometer respectively.

Results

A triply oxidized His residue was detected along with a second doubly oxidized His residue in an IgG1. Both of these oxidized His residues are located near Trp residues. In order to investigate the role of Trp photosensitization in His oxidation we synthesized model peptides and Ala mutants. Peptides exposed to ICH light stress conditions revealed a small percent of triply oxidized His in the Trp-containing peptide sequences but not in their corresponding Ala mutants.

Conclusions

The differences in product formation under different photo-irradiation conditions underline the importance of light source, irradiation wavelengths and primary sequence in the photosensitivity of proteins.

     

Use of Cyclodextrin as a Novel Agent in the SEC-HPLC Mobile Phase to Mitigate the Interactions of Proteins or Peptide or their Impurities with the Residual Silanols of Commercial SEC-HPLC Columns with Improved Separation and Resolution

Purpose

Accurate quantification of the intact proteins, antibodies or peptides and their impurities without interaction to silanols of HPLC column.

Methods

Hydroxypropyl ß Cyclodextrin (HPCD) is added in the mobile phase at different concentrations. Different commercial SEC-HPLC columns and biologics with a molecular weight ranging from 5.8 kDa to 150kDa were assessed with and without cyclodextrin.

Results

Addition of non-ionic sugars such as Hydroxypropyl ß Cyclodextrin in the mobile phase, resulted improved peak performance such as theoretical plates, peak resolution, peak width, peak height, and improved quantification of aggregates in biologics such as antibodies Humira and Actemra, and peptides such as insulin. There is an increase in peak height, reduced retention time, increased plate and reduced peak width with increasing concentration of cyclodextrin studied.

Discussion

High ionic strength, basic amino acids such as arginine, organic solvents (with a concentration low enough not to precipitate protein), sodium perchlorate and ion pairing agents in the mobile phase used for separation of peptides, proteins and antibodies to prevent silanol interaction. These commonly used solutions are not always successful, as they not only interact with the biologic, but are sometimes, not compatible. The non-ionic cyclodextrin itself does not cause protein aggregation but prevents the nonspecific binding or interaction of protein itself and thereby allowing for improved resolution, and accurate quantification of aggregates in antibodies, and peptides. The data on the separation in presence of cyclodextrin in the mobile phase showed higher peak resolution, improved peak shape, accurate apparent molecular weight, improved efficiency, and less peak tailing for biological products.

Conclusion

Hydroxypropyl ß Cyclodextrin in the mobile phase, resulted improved SEC-HPLC resolution, and quantitation of aggregates in biologics by preventing the interaction of biologics to silanol of the commercial SEC-HPLC columns.

     

The Effort of Health Management for Workers in Y Combined Cycle Power Plant in Korea

Objective

This study promotes health management activities in Y combined cycle power plants in Korea, focusing on occupational health activities, such as preventing cardiovascular disease and musculoskeletal disorders and managing work environment measurements.

Methods

The results of the present study were collected from the company’s internal documents and reports in Y combined cycle power plant.

Results

Diverse results for workplace activities are summarized. Furthermore, this study discusses attempts to reduce potential safety risks and to improve workers’ health conditions at the Y combined cycle power plants in Korea.

Conclusion

The Y combined cycle plant discussed seeks to prevent accidents to improve workers’ health; thus, specific efforts related to onsite health and expected results for workers are evaluated.

     

Protected Graft Copolymer (PGC) Basal Formulation of Insulin as Potentially Safer Alternative to Lantus® (Insulin-Glargine): A Streptozotocin-Induced,Diabetic Sprague Dawley Rats Study

Purpose

To develop a long-acting formulation of native human insulin with a similar pharmacodynamics (PD) profile as the insulin analogue insulin glargine (Lantus®, Sanofi-Aventis) with the expectation of retaining native human insulin’s superior safety profile as insulin glargine is able to activate the insulin-like growth factor 1 (IGF-1) receptor and is linked to a number of malignancies at a higher rate than regular human insulin.

Methods

Development of protected graft copolymer (PGC) excipients that bind native human insulin non-covalently and testing blood glucose control obtained with these formulations in streptozotocin-induced diabetic Sprague Dawley rats compared to equally dosed insulin glargine.

Results

PGC-formulations of native human insulin are able to control blood glucose to the same extent and for the same amount of time after s.c. injection as the insulin analogue insulin glargine. No biochemical changes were made to the insulin that would change receptor binding and activation with their possible negative effects on the safety of the insulin.

Conclusion

Formulation with the PGC excipient offers a viable alternative to biochemically changing insulin or other receptor binding peptides to improve PD properties.

Open image in new window

Figure Blood glucose development in STZ-diabetic Sprague Dawley rats after s.c. injection of 1 mg/kg regular human insulin formulated with formulations 605c, 421a, and 421b, or an equivalent dose of insulin glargine.

     

Mutagenicities of 2-Propylaniline and 4-Propylaniline Determined by a Bacterial Reverse Mutation (<Emphasis Type="Italic">Ames</Emphasis>) Assay

Objective

Although the organic compounds, 2-propylaniline and 4-propylaniline are frequently used in many industrial sectors, and have little information about the potential genetic toxicity, and it is covered by the Occupational Safety & Health Act (OSHAct) in Korea.

Methods

The mutation test of 2-propylaniline and 4-propylaniline was evaluated in five different doses for each chemical through a well-known Ames bacterial mutation test. This test was performed regardless of metabolic activation.

Results

In this assay, we obtained positive results under all tested conditions, indicating that these two chemicals have mutagenic and potentially carcinogenic properties.

Conclusion

Both 2-propylaniline and 4-propylaniline were mutagenic under the conditions of these tests. This result means that all of these chemicals exhibit mutations and potential carcinogenicity.

     

Intranasal Fentanyl Intoxication Leading to Diffuse Alveolar Hemorrhage

Context

Increasing rates of opioid abuse, particularly fentanyl, may lead to more presentations of unusual effects of opioid toxicity. Diffuse alveolar hemorrhage is a rare complication of fentanyl overdose.

Case Details

A 45-year-old male presented in hypoxic respiratory failure secondary to diffuse alveolar hemorrhage requiring intubation. Comprehensive drug screening detected fentanyl without exposure to cocaine. Further history upon the patient’s recovery revealed exposure to snorted fentanyl powder immediately prior to presentation.

Discussion

Diffuse alveolar hemorrhage is a potential, though rare, presentation of opioid intoxication.

Conclusions

Recognition of less common complications of opioid abuse such as diffuse alveolar hemorrhage is important in proper management of overdoses.

     

<Emphasis Type="Italic">In Vivo</Emphasis> Toxicity and Immunological Characterization of Detoxified Recombinant Botulinum Neurotoxin Type A

Purpose

A double-mutant E224A/E262A full-length botulinum neurotoxin (BoNT) Type A with structural similarity to native BoNT/A but lacking the endopeptidase activity provides an ideal surrogate for testing pharmacokinetics and immunochemical characteristics of BoNT.

Methods

We determined lethality (LD₅₀) of deactivated recombinant botulinum neurotoxin (drBoNT/A) to be 24.0 μg by intraperitoneal route (i.p). The polypeptide drBoNT/A labeled with near infra-red dye 800 (NIR 800) was used to examine its distribution to different organs using whole body imaging when administered to mice via intravenous (i.v) or i.p route. Also, drBoNT/A was used to evaluate its immunogenicity in Balb/C mice model.

Results

drBoNT/A was found to be highly immunogenic when tested under various in vivo conditions in Balb/C mice model. For the first time we have demonstrated that a full length 150 kDa drBoNT/A, by administering via inhalation route in mice model, has evoked both circulating immunoglobulin levels of IgG and secretory IgA at the mucosal surface. The immunoglobulin levels were sufficient enough to protect against the challenge dose of native BoNT toxin in mice model. Tissue distribution of drBoNT/A seems to be similar to that of native toxin.

Conclusions

Based on the characteristics described in this report this nontoxic holotoxin protein will assist us to explore the window of opportunity available for therapeutic treatment in case of unnatural poisoning, and also it can be an effective vaccine candidate.

     

Intravenous Poison Hemlock Injection Resulting in Prolonged Respiratory Failure and Encephalopathy

Background

Poison hemlock (Conium maculatum) is a common plant with a significant toxicity. Data on this toxicity is sparse as there have been few case reports and never a documented poisoning after intravenous injection.

Objectives

We present a case of intravenous poison hemlock injection encountered in the emergency department.

Case Report

We describe a 30-year-old male who presented to the emergency department after a brief cardiac arrest after injecting poison hemlock. The patient had return of spontaneous circulation in the emergency department but had prolonged muscular weakness and encephalopathy later requiring tracheostomy.

Conclusion

Intravenous injection of poison hemlock alkaloids can result in significant toxicity, including cardiopulmonary arrest, prolonged weakness, and encephalopathy.

     

Effect of Nanoparticle Surface on the HPLC Elution Profile of Liposomal Nanoparticles

Purpose

Nanoparticles have been used in diverse areas, and even broader applications are expected in the future. Since surface modification can influence the configuration and toxicity of nanoparticles, a rapid screening method is important to ensure nanoparticle quality.

Methods

We examined the effect of the nanoparticle surface morphology on the HPLC elution profile using two types of 100-nm liposomal nanoparticles (AmBisome^? and DOXIL^?).

Results

These 100-nm-sized nanoparticles eluted before the holdup time (about 4 min), even when a column packed with particles with a relatively large pore size (30 nm) was used. The elution time of the nanoparticles increased with pegylation of the nanoparticles and protein adsorption to the nanoparticles; however, the nanoparticles still eluted before the holdup time.

Conclusions

The results of this study indicate that HPLC is a suitable tool for rapid evaluation of the surface of liposomal nanoparticles.

     

Suspected Adulteration of Commercial Kratom Products with 7-Hydroxymitragynine

Introduction

Kratom (Mitragyna speciosa), a plant native to Southeast Asia, has been used for centuries for its stimulant and opium-like effects. Mitragynine and 7-hydroxymitragynine, exclusive to M. speciosa, are the alkaloids primary responsible for Kratom's biologic and psychoactive profile, and likely contribute to its problematic use. We purchased several commercially available Kratom analogs for analysis and through our results, present evidence of probable adulteration with the highly potent and addictive plant alkaloid, 7-hydroxymitragynine.

Methods

A simple and sensitive LC-MS/MS method was developed for simultaneous quantification of mitragynine and 7-hydroxymitragynine in methanol extract of marketed Kratom supplements.

Results

We found multiple commercial Kratom products to have concentrations of 7-hydroxymitragynine that are substantially higher than those found in raw M. speciosa leaves.

Conclusions

We have found multiple packaged commercial Kratom products likely to contain artificially elevated concentrations of 7-hydroxymitragynine, the alkaloid responsible for M. speciosa's concerning mechanistic and side effect profile. This study describes a unique form of product adulteration, which stresses the importance of increased dietary supplement oversight of Kratom-containing supplements.

     

Drug Regulation and Oversight,from Local to Global

Purpose

The purpose of this perspective piece is to address the potential for drug and medical product innovation through sound regulation and strengthened international harmonization.

Methods

Current literature, recommendations and guidelines in regulatory agencies assisted in this perspective review.

Results

Multiple guidelines and recommendations provide for strategic planning and process improvement capabilities at local, national and international levels.

Conclusions

Seeking best practice starts with identifying and improving individual nation drug regulatory bodies, including the US Food and Drug Administration (FDA). Inefficiency causes and process improvement solutions have been suggested and outlined in strategic plans at the FDA as well as with multiple stakeholder organizations and public-private partnerships. Cohesively, these groups should be tasked with formal, consistent updates on improvement as well as ongoing supportive research and evaluation of the changes implemented. Simultaneously, the international community has a tremendous opportunity to act on best practice for drug and medical product innovation by aligning sound and consistent approach to regulation.

     

A Study on Toxicity of Chemically Synthesised Silver Nanoparticle on <Emphasis Type="Italic">Eudrilus eugeniae</Emphasis>

Objective

To evaluate the toxicity of the silver nanoparticle against earthworms - Eudrilus eugeniae, a model for soil organism.

Methods

Silver nanoparticles were synthesised by chemical reduction and further characterised by UV Visible Spectroscopy and FeSEM. Earthworms were allowed to interact with different concentrations of the synthesized silver nanoparticles. After exposure period, histology and inductively coupled plasma optical emission spectrometry (ICP-OES) were done to determine the accumulation and toxic effects exhibited by the nanoparticle on earthworms.

Results

The synthesized nanoparticle was found to be between the size of 180 and 200 nm. Histology studies revealed that silver nanoparticles to cause fibrosis, lipofuscin-like deposits and also gut disruption in earthworms.

Conclusion

Silver nanoparticles were found to be toxic to Eudrilus eugeniae, which was evidenced by histology.

     

Evaluation of Pharmacokinetics of Bioreducible Gene Delivery Vectors by Real-time PCR

Purpose

To investigate pharmacokinetics of reversibly stabilized DNA nanoparticles (rSDN) using a single-step lysis RT-PCR.

Methods

rSDN were prepared by coating bioreducible polycation/DNA polyplexes with multivalent N-(2-hydroxypropyl)methacrylamide (HPMA) copolymers. Targeted polyplexes were formulated by linking cyclic RGD ligand (c(RGDyK)) to the HPMA surface layer of rSDN. The pharmacokinetic parameters in tumor-bearing mice were analyzed by PKAnalyst®.

Results

The pharmacokinetics of naked plasmid DNA, simple DNA polyplexes, rSDN, and RGD-targeted rSDN exhibited two-compartment model characteristics with area under the blood concentration–time curve (AUC) increasing from 1,102 ng?ml^?1?min^?1 for DNA to 3,501 ng?ml^?1?min^?1 for rSDN. Non-compartment model analysis revealed increase in mean retention time (MRT) from 4.5 min for naked DNA to 22.9 min for rSDN.

Conclusions

RT-PCR is a sensitive and convenient method suitable for analyzing pharmacokinetics and biodistribution of DNA polyplexes. Surface stabilization of DNA polyplexes can significantly extend their MRT and AUC compared to naked DNA. DNA degradation in rSDN in blood circulation, due to a combined effect of disulfide reduction and competitive reactions with charged molecules in the blood, contributes to DNA elimination.

     

Formulation of High-Performance Dry Powder Aerosols for Pulmonary Protein Delivery

Purpose

Pulmonary delivery of biologics is of great interest, as it can be used for the local treatment of respiratory diseases or as a route to systemic drug delivery. To reach the full potential of inhaled biologics, a formulation platform capable of producing high performance aerosols without altering protein native structure is required.

Methods

A formulation strategy using Particle Replication in Non-wetting Templates (PRINT) was developed to produce protein dry powders with precisely engineered particle morphology. Stability of the incorporated proteins was characterized and the aerosol properties of the protein dry powders was evaluated in vitro with an Andersen Cascade Impactor (ACI).

Results

Model proteins bovine serum albumin (BSA) and lysozyme were micromolded into 1 μm cylinders composed of more than 80% protein, by mass. Extensive characterization of the incorporated proteins found no evidence of alteration of native structures. The BSA formulation produced a mass median aerodynamic diameter (MMAD) of 1.77 μm ± 0.06 and a geometric standard deviation (GSD) of 1.51 ± 0.06 while the lysozyme formulation had an MMAD of 1.83 μm ± 0.12 and a GSD of 1.44 ± 0.03.

Conclusion

Protein dry powders manufactured with PRINT could enable high-performance delivery of protein therapeutics to the lungs.

     

Assessment of a United States pharmaceutical care model for nursing homes in the United Kingdom

Objective

To assess the suitability of an American model of pharmaceutical care for nursing home residents (The Fleetwood model) for application in nursing homes in the United Kingdom.

Method

Pharmacists (those from a hospital setting or involved in prescribing support), general practitioners, nursing home managers and advocates for older people were invited to participate in semi-structured interviews or focus groups. The American Fleetwood model was explained to all participants who were asked for their views and opinions on how such a model could be adapted for use in the UK setting. All interviews and focus groups were tape-recorded, transcribed verbatim and analysed using the framework method.

Main outcome measure

An adapted model of pharmaceutical care for use in UK nursing homes.

Results

There was general concern about prescribing in nursing homes, particularly in relation to psychoactive drugs. All participants were supportive of the proposed model of care and endorsed the greater involvement of pharmacists. However, participants also recognised that unlike pharmacists in the US nursing home setting for which the Fleetwood model had been developed, pharmacists implementing this approach in the UK would face major challenges in relation to access to records (medical and medication), prescribers and residents.

Conclusion

The findings highlighted the key elements of access which will need to be considered if this model of pharmaceutical care is to be applied to nursing home residents in the UK.

Impact of findings on practice

The model has been revised to take account of the challenges relating to access and will be tested in a randomised controlled trial.