Dynamics of in silico leukocyte rolling, activation, and adhesion

BACKGROUND: We present a multilevel, agent based, in silico model that represents the dynamics of rolling, activation, and adhesion of individual leukocytes in vitro. Object-oriented software components were designed, verified, plugged together, and then operated in ways that represent the molecular and cellular mechanisms believed responsible for leukocyte rolling and adhesion. The result is an in silico analogue of an experimental in vitro system. The experimentally measured, phenotypic attributes of the analogue were compared and contrasted to those of leukocytes in vitro from three different experimental conditions. RESULTS: The individual in silico dynamics of "rolling" on simulated P-selectin, and separately on simulated VCAM-1, were an acceptable match to individual in vitro distance-time and velocity-time measurements. The analogues are also able to represent the transition from rolling to adhesion on P-selectin and VCAM-1 in the presence of GRO-α chemokine. The individual in silico and in vitro behavioral similarities translated successfully to population level measures. These behavioral similarities were enabled in part by subdividing the functionality of the analogue's surface into 600 independent, "cell"-controlled, equally capable modules of comparable functionality. CONCLUSION: The overlap in phenotypic attributes of our analogue with those of leukocytes in vitro confirm the considerable potential of our model for studying the key events that determine the behavioral outcome of individual leukocytes during rolling, activation, and adhesion. Our results provide an important foundation and framework for future in silico research into plausible causal links between well-documented, subcellular molecular level events and the variety of systemic phenotypic attributes that distinguish normal leukocyte adhesion from abnormal disease-associated adhesion

Symmetry and designability for lattice protein models

Native protein folds often have a high degree of symmetry. We study the relationship between the symmetries of native proteins, and their designabilities -- how many different sequences encode a given native structure. Using a two-dimensional lattice protein model based on hydrophobicity, we find that those native structures that are encoded by the largest number of different sequences have high symmetry. However only certain symmetries are enhanced, e.g. x/y-mirror symmetry and $180^o$ rotation, while others are suppressed. If it takes a large number of mutations to destabilize the native state of a protein, then, by definition, the state is highly designable. Hence, our findings imply that insensitivity to mutation implies high symmetry. It appears that the relationship between designability and symmetry results because protein substructures are also designable. Native protein folds may therefore be symmetric because they are composed of repeated designable substructures.Comment: 13 pages, 10 figure

Measurement of teicoplanin by liquid chromatography-tandem mass spectrometry:development of a novel method

Teicoplanin is an antibiotic used for the treatment of endocarditis, osteomyelitis, septic arthritis and methicillin-resistant Staphylococcus aureus. Teicoplanin is emerging as a suitable alternative antibiotic to vancomycin, where their trough serum levels are monitored by immunoassay routinely. This is the first report detailing the development of a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for measuring teicoplanin in patients' serum

Measurements of Osteoanabolic agents PTH (1-34) and PTHrP (1-36) in therapeutic studies and clinical diagnostics

Background: Teriparatide PTH (1-34) is an osteoanabolic agent for treatment of osteoporosis. PTH (1-34) can also be used as replacement therapy in hypoparathyroidism and to accelerate fracture healing. Abaloparatide, PTHrP (1-36) analogue is a novel anabolic drug for treatment of osteoporosis. PTH (1-34) has also been used to assess response to PTH in conditions such as pseudohypoparathyroidism (PHP) (Ellsworth-Howard test (EHT))  Aims: To review the use of PTH (1-34) measurements in drug development studies, and in the diagnosis of patients with PHP. To highlight the potential use of measurement of PTHrP (1-36) using our LC-MS/MS method for measurement of intact PTHrP (1-36), intact PTH (1-34) and their respective oxidised forms simultaneously.  Methods: Pharmacokinetic (PK) profiles from human subjects given either single subcutaneous (sc) injection of 20 ug Teriparatide (n=6) or 0.69 mg (n=4), 2.07 mg (n=6) oral PTH (1-34) (EnteraBio) were analysed using a validated LC-MS/MS method for intact/oxidised PTH (1-34). In EHT, urinary phosphate (spectrophotometric assay; Roche, Germany) and urine/plasma cyclic adenosine 3’,5’–monophosphate (cAMP) (LC-MS/MS) were performed on samples before and after 20ug sc adminstration of Teriparatide.  Results/Discussion: PK profiles (Figure 1A) of oral PTH (1-34) showed a rapid absorption then rapid elimination. In contrast, teriparatide injection showed a slower rate of plasma clearance, possibly due to continuous absorption from the site of administration. C­max was proportional to oral dosage given and the 2.07 mg of oral PTH (1-34) produced comparable Cmax to that produced by 20ug teriparatide injection (Figure 1B). We found the oxidised form of PTH (1-34) represent 20-30% of intact PTH (1-34) in the studied subjects. The EHT profile from a patient suspected of PHP showed a lack of cAMP response despite significant increase in plasma PTH (1-34) concentration. On the contrary, a post dose plasma cAMP concentration of >100 pmol/L and an increase from baseline level of urine cAMP exclude the diagnosis of PHP. Our LC-MS/MS PTHrP (1-36) assay produced a linear calibration curve from 10-2000 pg/mL (r2 >0.990), inter-/ intra-assay CV of 98.6% (CV 3.6%).  Conclusion: Our method for measurements of intact/oxidised form PTH (1-34) and PTHrP (1-36) can offer new insights into the therapeutic use of osteoanabolic agents, and the development of combination therapy with other anti-resorptive/anti-remodelling agents

Antioxidant effects of sulforaphane in human HepG2 cells and immortalised hepatocytes

Sulforaphane (SFN) has shown anti-cancer effects in cellular and animal studies but its effectiveness has been limited in human studies. Here, the effects of SFN were measured in both human hepatocyte (HHL5) and hepatoma (HepG2) cells. Results showed that SFN inhibited cell viability and induced DNA strand breaks at high doses (≥ 20 µM). It also activated the nuclear factor (erythroid-derived 2)-like 2 (Nrf2), and increased intracellular glutathione (GSH) levels at 24 hours. Pre-treatment with a low dose SFN (≤5 µM) protected against hydrogen peroxide (H2O2)-induced cell damage. High doses of SFN were more toxic towards HHL5 compared to HepG2 cells; the difference is likely due to the disparity in the responses of Nrf2-driven enzymes and -GSH levels between the two cell lines. In addition, HepG2 cells hijacked the cytoprotective effect of SFN over a wider dose range (1.25 - 20 µM) compared to HHL5. Manipulation of levels of GSH and Nrf2 in HepG2 cells confirmed that both molecules mediate the protective effects of SFN against H2O2. The non-specific nature of SFN in the regulation of cell death and survival could present undesirable risks, i.e. be more toxic to normal cells, and cause chemo-resistance in tumor cells. These issues should be addressed in the context for cancer prevention and treatment before large scale clinical trials are undertaken

Vitamin D measurement, the debates continue, new analytes have emerged, developments have variable outcomes

The demand for measurement of vitamin D metabolites for clinical diagnosis and to advance our understanding of the role of vitamin D in human health has significantly increased in the last decade. New developments in technologies employed have enabled the separation and quantification of additional metabolites and interferences. Also, developments of immunoassays have changed the landscape. Programmes and materials for assay standardisation, harmonisation and the expansion of the vitamin D external quality assurance scheme (DEQAS) with the provision of target values as measured by a reference measurement procedure have improved standardisation, quality assurance and comparability of measurements. In this article, we describe developments in the measurement of the commonly analysed vitamin D metabolites in clinical and research practice. We describe current analytical approaches, discuss differences between assays, their origin, and how these may be influenced by physiological and experimental conditions. The value of measuring metabolites beyond 25 hydroxyvitamin D (25(OH)D), the marker of vitamin D status, in routine clinical practice is not yet confirmed. Here we provide an overview of the value and application of the measurement of 1,25 dihydroxyvitamin D, 24,25 dihydroxyvitamin D and free 25OHD in the diagnosis of patients with abnormalities in vitamin D metabolism and for research purposes

Effect of carbohydrate feeding on the bone metabolic response to running

Bone resorption is increased after running, with no change in bone formation. Feeding during exercise might attenuate this increase, preventing associated problems for bone. This study investigated the immediate and short-term bone metabolic responses to carbohydrate (CHO) feeding during treadmill running. Ten men completed two 7-day trials, once being fed CHO (8% glucose immediately before, every 20 min during, and immediately after exercise at a rate of 0.7 g CHO·kg body mass-1·h-1) and once being fed placebo (PBO). On day 4 of each trial, participants completed a 120-min treadmill run at 70% of maximal oxygen consumption (VO2 max). Blood was taken at baseline (BASE), immediately after exercise (EE), after 60 (R1) and 120 (R2) min of recovery, and on three follow-up days (FU1-FU3). Markers of bone resorption [COOH-terminal telopeptide region of collagen type 1 (β-CTX)] and formation [NH2-terminal propeptides of procollagen type 1 (P1NP)] were measured, along with osteocalcin (OC), parathyroid hormone (PTH), albumin-adjusted calcium (ACa), phosphate, glucagon-like peptide-2 (GLP-2), interleukin-6 (IL-6), insulin, cortisol, leptin, and osteoprotogerin (OPG). Area under the curve was calculated in terms of the immediate (BASE, EE, R1, and R2) and short-term (BASE, FU1, FU2, and FU3) responses to exercise. β-CTX, P1NP, and IL-6 responses to exercise were significantly lower in the immediate postexercise period with CHO feeding compared with PBO (β-CTX: P=0.028; P1NP: P=0.021; IL-6: P=0.036), although there was no difference in the short-term response (β-CTX: P=0.856; P1NP: P=0.721; IL-6: P=0.327). No other variable was significantly affected by CHO feeding during exercise. We conclude that CHO feeding during exercise attenuated the β-CTX and P1NP responses in the hours but not days following exercise, indicating an acute effect of CHO feeding on bone turnover

The effect of 14 weeks of vitamin D3 supplementation on antimicrobial peptides and proteins in athletes

Heavy training is associated with increased respiratory infection risk and antimicrobial proteins are important in defence against oral and respiratory tract infections. We examined the effect of 14 weeks of vitamin D3 supplementation (5000 IU/day) on the resting plasma cathelicidin concentration and the salivary secretion rates of secretory immunoglobulin A (SIgA), cathelicidin, lactoferrin and lysozyme in athletes during a winter training period. Blood and saliva were obtained at the start of the study from 39 healthy men who were randomly allocated to vitamin D3 supplement or placebo. Blood samples were also collected at the end of the study; saliva samples were collected after 7 and 14 weeks. Plasma total 25(OH)D concentration increased by 130% in the vitamin D3 group and decreased by 43% in the placebo group (both P=0.001). The percentage change of plasma cathelicidin concentration in the vitamin D3 group was higher than in the placebo group (P=0.025). Only in the vitamin D3 group, the saliva SIgA and cathelicidin secretion rates increased over time (both P=0.03). A daily 5000 IU vitamin D3 supplement has a beneficial effect in up-regulating the expression of SIgA and cathelicidin in athletes during a winter training period which could improve resistance to respiratory infections

Phage display selected magnetite interacting Adhirons for shape controlled nanoparticle synthesis

Adhirons are robust, well expressing, peptide display scaffold proteins, developed as an effective alternative to traditional antibody binding proteins for highly specific molecular recognition applications. This paper reports for the first time the use of these versatile proteins for material binding, and as tools for controlling material synthesis on the nanoscale. A phage library of Adhirons, each displaying two variable binding loops, was screened to identify specific proteins able to interact with [100] faces of cubic magnetite nanoparticles. The selected variable regions display a strong preference for basic residues such as lysine. Molecular dynamics simulations of amino acid adsorption onto a [100] magnetite surface provides a rationale for these interactions, with the lowest adsorption energy observed with lysine. These proteins direct the shape of the forming nanoparticles towards a cubic morphology in room temperature magnetite precipitation reactions, in stark contrast to the high temperature, harsh reaction conditions currently used to produce cubic nanoparticles. These effects demonstrate the utility of the selected Adhirons as novel magnetite mineralization control agents using ambient aqueous conditions. The approach we outline with artificial protein scaffolds has the potential to develop into a toolkit of novel additives for wider nanomaterial fabrication

Enhanced bioavailability and reduced pharmacokinetic variability of Oral PTH (1-34) in man

An orally administered PTH may have prodigious advantages in the treatment of hypoparathyroidism and osteoporosis. Unfortunately, the oral delivery of biologic macromolecules is characterized by a negligible bioavailability and a high dose-to-dose variability in absorption, resulting in difficulty in accurately titrating the drug effect. We present clinical study data of a novel oral peptide delivery technology demonstrating an enhanced bioavailability with reduced Cmax variability. Methods: A Phase I, open label crossover pharmacokinetic (PK) study to assess the safety and PK of oral PTH (1-34) in ten healthy male adult volunteers was conducted. The PK profile of a fixed dose - 1.5mg PTH (1-34) of three different oral formulations was compared. PTH (1-34) levels in the plasma of subjects was analyzed at a number of time points post administration, utilizing a PTH (1-34) immunoassay (IDS; Bolden, UK). In parallel, to assess the pharmacodynamic (PD) effect, serum calcium of subjects receiving the different formulations of oral PTH (1-34) was analyzed. Results: PK profiles of all oral PTH (1-34) formulations were characterized by a rapid absorption and elimination. The systemic exposure (AUC) of the basic oral formulation and two modified formulation versions were 3481 ±1843 pg*min/mL, 7976 ±2556 pg*min/mL and 11369 ±3719 pg*min/mL (mean ± SE). The maximal plasma concentration (Cmax) of these formulations were 145 ±56pg/mL, 375 ±108pg/mL, and 481 ±101pg/mL, respectively. Cmax coefficients of variation (CV%) of the same formulations were 123%, 91% and 67%, respectively. Similarly to the drug absorption, PD response of the modified formulations, presented as the maximal relative increase in albumin adjusted calcium, was improved from 0.07 ±0.29mg/dL to 0.32 ±0.24mg/dL. Discussion: Inherent to oral drug delivery of biopharmaceuticals is the extremely low bioavailability and high absorption variability. The current results indicate that Entera’s delivery technology can overcome these two principal obstacles by achieving repeatable, clinically relevant systemic drug exposure. Entera’s proprietary delivery platform was optimized and achieved anenhancement in drug bioavailability in parallel with the significant decrease in its absorption variability. Similarly, its effect on blood calcium was enhanced by the novel oral formulation of PTH (1-34) pointing out the potential of the drug to be a first line treatment of hypoparathyroidism and osteoporosis