Iron-carbohydrate complexes treating iron anaemia: Understanding the nano-structure and interactions with proteins through orthogonal characterisation

Intravenous (IV) iron-carbohydrate complexes are widely used nanoparticles (NPs) to treat iron deficiency anaemia, often associated with medical conditions such as chronic kidney disease, heart failure and various inflammatory conditions. Even though a plethora of physicochemical characterisation data and clinical studies are available for these products, evidence-based correlation between physicochemical properties of iron-carbohydrate complexes and clinical outcome has not fully been elucidated yet. Studies on other metal oxide NPs suggest that early interactions between NPs and blood upon IV injection are key to understanding how differences in physicochemical characteristics of iron-carbohydrate complexes cause variance in clinical outcomes. We therefore investigated the core-ligand structure of two clinically relevant iron-carbohydrate complexes, iron sucrose (IS) and ferric carboxymaltose (FCM), and their interactions with two structurally different human plasma proteins, human serum albumin (HSA) and fibrinogen, using a combination of cryo-scanning transmission electron microscopy (cryo-STEM), x-ray diffraction (XRD), small-angle x-ray scattering (SAXS) and small-angle neutron scattering (SANS). Using this orthogonal approach, we defined the nano-structure, individual building blocks and surface morphology for IS and FCM. Importantly, we revealed significant differences in the surface morphology of the iron-carbohydrate complexes. FCM shows a localised carbohydrate shell around its core, in contrast to IS, which is characterised by a diffuse and dynamic layer of carbohydrate ligand surrounding its core. We hypothesised that such differences in carbohydrate morphology determine the interaction between iron-carbohydrate complexes and proteins and therefore investigated the NPs in the presence of HSA and fibrinogen. Intriguingly, IS showed significant interaction with HSA and fibrinogen, forming NP-protein clusters, while FCM only showed significant interaction with fibrinogen. We postulate that these differences could influence bio-response of the two formulations and their clinical outcome. In conclusion, our study provides orthogonal characterisation of two clinically relevant iron-carbohydrate complexes and first hints at their interaction behaviour with proteins in the human bloodstream, setting a prerequisite towards complete understanding of the correlation between physicochemical properties and clinical outcome.

Dynamic Light Scattering Analysis for the Determination of the Particle Size of Iron-Carbohydrate Complexes

Intravenously administered iron-carbohydrate nanoparticle complexes are widely used to treat iron deficiency. This class includes several structurally heterogeneous nanoparticle complexes, which exhibit varying sensitivity to the conditions required for the methodologies available to physicochemically characterize these agents. Currently, the critical quality attributes of iron-carbohydrate complexes have not been fully established. Dynamic light scattering (DLS) has emerged as a fundamental method to determine intact particle size and distribution. However, challenges still remain regarding the standardization of methodologies across laboratories, specific modifications required for individual iron-carbohydrate products, and how the size distribution can be best described. Importantly, the diluent and serial dilutions used must be standardized. The wide variance in approaches for sample preparation and data reporting limit the use of DLS for the comparison of iron-carbohydrate agents. Herein, we detail a robust and easily reproducible protocol to measure the size and size distribution of the iron-carbohydrate complex, iron sucrose, using the Z-average and polydispersity index.

Factors influencing safety and efficacy of intravenous iron-carbohydrate nanomedicines: From production to clinical practice

Iron deficiency is an important subclinical disease affecting over one billion people worldwide. A growing body of clinical records supports the use of intravenous iron-carbohydrate complexes for patients where iron replenishment is necessary and oral iron supplements are either ineffective or cannot be tolerated by the gastrointestinal tract. A critical characteristic of iron-carbohydrate drugs is the complexity of their core-shell structure, which has led to differences in the efficacy and safety of various iron formulations. This review describes parameters influencing the safety and effectiveness of iron-carbohydrate complexes during production, storage, handling, and clinical application. We summarized the physicochemical and biological assessments of commercially available iron carbohydrate nanomedicines to provide an overview of publicly available data. Further, we reviewed studies that described how subtle differences in the manufacturing process of iron-carbohydrate complexes can impact on the physicochemical, biological, and clinical outcomes of original product versus their intended copies or so-called iron "similar" products.

Iron sucrose: assessing the similarity between the originator drug and its intended copies

Iron sucrose (IS) is a complex nanocolloidal intravenous suspension used in the treatment of iron-deficiency anemia. Follow-on IS products (iron sucrose similars (ISSs)) have obtained marketing authorization by the generic pathway, implying that identical copies of IS may be manufactured. However, recent prospective and retrospective clinical studies showed discrepancies in clinical outcomes, which might be related to differences in physicochemical properties. The aim of this work is to measure and compare the physicochemical properties of IS and three ISSs available in the market using innovative analytical procedures. The comprehensive elucidation of size, size distribution, morphology, and stability of these complex drugs revealed very significant differences between the products. This study serves to provide the basis to define critical quality attributes that may be linked to differences in clinical outcome and thus may contribute to an adequate regulatory approach for IS and its follow-on products.

Diluting ferric carboxymaltose in sodium chloride infusion solution (0.9% w/v) in polypropylene bottles and bags: effects on chemical stability

OBJECTIVES

This study was designed to assess the physicochemical stability of colloidal ferric carboxymaltose solution (Ferinject) when diluted and stored in polypropylene (PP) bottles and bags for infusion.

METHODS

Two batches of ferric carboxymaltose solution (Ferinject) were diluted (500 mg, 200 mg and 100 mg iron in 100 mL saline) in PP bottles or bags under aseptic conditions. The diluted solutions were stored at 30°C and 75%±5% relative humidity (rH) for 72 h, and samples were withdrawn aseptically at preparation and after 24 h, 48 h and 72 h. Multiple parameters were used to test stability-related measures (pH, total iron and iron (II) content, molecular weight range determination, microbial contamination and particles count ≥10 μm).

RESULTS

Overall, Ferinject diluted in 0.9% (w/v) NaCl solution and stored in PP bottles and bags was stable within the specifications for the complex and the acceptability limits set for all assays. In both containers, total iron content remained stable, within 10% of the theoretical iron content, and levels of iron (II) remained far below the threshold of acceptability. All preparations were free from sediments, particle numbers were acceptable and there was no microbial contamination. The molecular weight distribution and polydispersity index were also acceptable.

CONCLUSIONS

Under the tested experimental conditions, colloidal ferric carboxymaltose solution (Ferinject) diluted in saline in PP infusion bottles or bags demonstrated physical and chemical stability for up to 72 h at 30°C and 75% rH. Because of the lack of additional clinical data, when using ferric carboxymaltose, physicians/pharmacists should refer to the dilution and storing recommendations given in the product's summary of product characteristics.

[Retrospective analysis of tuberculosis caused by Mycobacterium bovis 2004 - 2008]

BACKGROUND

mycobacterium bovis is a rare cause of tuberculosis in Germany. Epidemiological data are sparse.

METHODS

we have carried out a retrospective analysis of all patients diagnosed with tuberculosis caused by M. BOVIS in a pneumological referral centre between 2004 and 2008.

RESULTS

M. bovis was isolated in 8 out of 203 (3,9  %) patients with a new diagnosis of tuberculosis. The median age of these patients was 69 years, and 7 out of 8 showed risk factors for reactivation of a latent tuberculosis infection. In 4 patients (50  %) an extrapulmonary manifestation was present. All isolates of M. bovis were resistant to pyrazinamide, one isolate had an additional resistance to isoniazide. In 6 out of 8 patients prolonged tuberculostatic treatment of 8 - 12 months was recommended.

CONCLUSIONS

the proportion of tuberculosis caused by M. bovis was higher than that reported for Germany (3.9 vs. 1,5 %). Predominantly elderly patients with risk factors for reactivation of a latent tuberculosis infection were affected. In accordance with the literature a high rate of extrapulmonary manifestations was detected. Because of the genetic resistance of M. bovis to pyrazinamide prolonged antimycobacterial treatment is recommended.

Is the umbo matrix of bivalve shells (Laternula elliptica) a climate archive?

Heavy metal accumulation into bivalve soft tissues has received increasing interest in recent years with respect to biomonitoring of environmental change including pollution. To a lesser extent, accretion of elements from the environment into bivalve hard structures (shells) has been investigated, although the importance of the shells as environmental archives has been acknowledged. Here we report element distribution within consecutive growth bands in the shells of the Antarctic soft shell clam Laternula elliptica, which is currently exposed to vast environmental change in Antarctic Peninsula coastal environments that undergo rapid climate warming. We performed a high spatial resolution analysis for Al, Fe, Mn, Cu, Pb and U in the shell umbo, by means of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Element ratios within the umbo did not resemble either the ratios in the surrounding seawater, the sedimenting material in Potter Cove, or even the Earth's crust basal composition. Mn and Cu were preferentially incorporated into the umbo. A strong decrease of element accretion with time could be related to lifetime respiration mass (R) of the animals. This indicates element accretion into the umbo and shell matrix to be largely a function of animal ecophysiology and life history, and these effects need to be considered in the context of potential usefulness of L. elliptica shells as environmental archives.

[Pulmonary nocardiosis with trimethoprime/sulphamethoxazole-resistant Nocardia paucivorans in a patient with no signs of immunosuppression]

This is so far the first published case report of a Nocardia paucivorans infection in an immunocompetent patient. A 54-year-old farmer was hospitalised with a history of coughing and fever for a period of five months. There was no indicator of either primary of secondary immunodeficiency in the prior medical history. A chest X-ray showed pneumonic infiltrates in the right middle und lower lobes, which progressed despite of antibiotic therapy with macrolides. A transbronchial biopsy revealed unspecific granulomatous inflammation of soft tissues. N. paucivorans - grew in cultures of sputum, bronchoalveolar lavage, and transbronchial biopsy. Oral antibiotic therapy was started with trimethoprime-sulphamethoxazole (TMP/SMX) and amoxicillin plus clavulanic acid. Susceptibility testing revealed high level resistance to TMP/SMX, which was consequently replaced by ciprofloxacin. Six months later, infiltrates had completely resolved and the patient did not report any residual clinical symptoms. The present case showed once again that nocardiosis is not limited to patients with immunodeficiencies. However, conservative combination therapy with oral antibiotics seems to be sufficiently effective for nocardiosis in the immunocompetent patient. For cases of suspected nocardiosis, a step-wise, risk-based diagnostic and therapeutic procedure is proposed.

Determination of the electron self-exchange rates of blue copper proteins by super-WEFT NMR spectroscopy

An NMR approach for determining the electron self-exchange (ESE) rate constants in blue copper proteins is presented. The approach uses the paramagnetic relaxation enhancement of resonances in 1D 1H super-WEFT spectra of partly oxidized (paramagnetic) proteins. These spectra allow a more precise determination of the relevant paramagnetic linebroadenings than conventional 1D 1H spectra and, thus, permit a more detailed investigation of the applicability of the linebroadenings for determining the electron exchange rates. The approach was used to estimate the ESE rate constant of plastocyanin from Anabaena variabilis. It was found that, although the rate constant can be determined accurately from a series of resonances, precise but erroneous constants are obtained from the resonances of the copper-bound residues, unless a narrow splitting of these resonances caused by the presence of two conformations is taken into account. As demonstrated here, this complication can be overcome by a correct analysis of the paramagnetic broadening of the combined double signals. Because of the high resolution and specific sensitivity of the approach it should be generally applicable to estimate electron transfer rates, k, if the paramagnetic relaxation enhancement R2p of the resonances can be determined, and the conditions k << R2p or delta omega(p) >> k >> R2p are fulfilled, delta omega(p) being the frequency separation between corresponding diamagnetic and paramagnetic sites.

The importance of intuition in the occupational medicine clinical consultation

Clinical consultation involves unspoken elements which flow between doctor and patient. They are vital ingredients of successful patient management but are not easily measured, objective or evidence-based. These elements include empathy and intuition for what the patient is experiencing and trying to express, or indeed suppressing. Time is needed to explore the instinctive feeling for what is important, particularly in present day society which increasingly recognizes the worth of psychosocial factors. This time should be available in the occupational health consultation. In this paper the importance of intuition and its essential value in the clinical interview are traced through history. Differences between intuition and empathy are explored and the use of intuition as a clinical tool is examined.

Cholecystokinin, gastrin and stress hormone responses in marathon runners

The purpose of this investigation was to determine the influence of long-distance running on the secretion of the gastrointestinal peptide hormones cholecystokinin (CCK) and gastrin. Several known stress hormones, ACTH, cortisol and norepinephrine, were also measured. The hormones were estimated before and after a competitive marathon run of 46.5 km and under control conditions a few weeks later. Except gastrin, all hormones were significantly higher under prerun conditions than under control conditions and were highest after the run. The most marked prerun elevation was in CCK. Therefore, CCK seems to be an important regulation factor in response to anticipatory stress.

Assay for tyrosine hydroxylase in hypothalamic homogenates using high-performance liquid chromatography with electrochemical detection

A highly sensitive and reliable assay for tyrosine hydroxylase (TH) activity in hypothalamic homogenates of male rats using high-performance liquid chromatography with electrochemical detection is described. Modification of sample preparation and chromatographic conditions led to a complete separation of L-3,4-dihydroxyphenylalanine (L-DOPA) and alpha-methyldopa from all interfering catecholamines and their metabolites. This assay is highly sensitive; 2 pmol of L-DOPA formed enzymatically could be measured. We were able to determine TH activity in tissue pieces weighing less than 1 mg. TH activity was not changed after storage for three months at -80 degrees C. In hypothalamic homogenates the Michaelis constant (KM) for L-tyrosine was 80.5 +/- 6.5 mumol/l and the maximal velocity (Vmax) was 132.5 +/- 10.5 pmol/mg of protein per min for L-DOPA formed enzymatically.

Effect of starvation on hypothalamic tyrosine hydroxylase activity in adult male rats

The activity of tyrosine hydroxylase (TH), the rate-limiting enzyme in norepinephrine synthesis, was determined in the mediobasal hypothalamus of adult male rats during acute and semistarvation. 3,4-Dihydroxyphenylalanine (DOPA) formed by TH was measured using high-performance liquid chromatography (HPLC). Acute starvation, as well as 3 weeks of semistarvation on a high-protein low-carbohydrate diet (CST PR) reduced TH activity significantly. Three weeks of a low-protein high-carbohydrate diet (CST KH) did not affect TH activity. While maximal velocity (Vmax) is significantly diminished in acute starvation and in semistarvation with a high-protein low-carbohydrate diet, Kd-values for tyrosine were not changed. These results suggest that TH activity in the brain contributes to decreased norepinephrine (NE) turnover in starvation.

Oral nafazatrom in man: effect on inhaled antigen challenge

The effect of oral nafazatrom (Bay g6575, 2 X 3 g) or placebo on inhaled antigen challenge was assessed in a double-blind study. In four subjects antigen challenge resulted in an immediate fall of 93.2 +/- 3.36% in airflow at 40% of vital capacity (Vp40) and a 45.85 +/- 4.95% reduction in forced partial expiratory volume at one second (FEV1). Neither nafazatrom nor placebo had any effect on baseline lung function or that after challenge. Leukotriene B4 was generated by ex vivo stimulus of blood with ionophore A23187, and quantified by high performance liquid chromatography (h.p.l.c.)-radioimmunoassay. No inhibition of LTB4 formation occurred ex vivo following oral nafazatrom, although addition of 10(-5) M nafazatrom to blood in vitro significantly inhibited LTB4 release. Peak plasma nafazatrom levels during the study ranged from 3.3 X 10(-7) M to 1.47 X 10(-6) M which are below the concentration (10(-5) M) at which significant 5-lipoxygenase inhibition occurs in vitro. Oral nafazatrom is ineffective as a 5-lipoxygenase inhibitor in man, probably because of poor bioavailability after administration.