Targeted removal of the FA2 site on human albumin prevents fatty acid-mediated inhibition of Zn2+ binding.

Zinc is required for virtually all biological processes. In plasma, Zn2+ is predominantly transported by human serum albumin (HSA), which possesses two Zn2+-binding sites of differing affinities (sites A and B). Fatty acids (FAs) are also transported by HSA, with seven structurally characterized FA-binding sites (named FA1-FA7) known. FA binding inhibits Zn2+-HSA interactions, in a manner that can impact upon hemostasis and cellular zinc uptake, but the degree to which binding at specific FA sites contributes to this inhibition is unclear. Wild-type HSA and H9A, H67A, H247A, and Y150F/R257A/S287A (FA2-KO) mutant albumins were expressed in Pichia pastoris. Isothermal titration calorimetry studies revealed that the Zn2+-binding capacity at the high-affinity Zn2+ site (site A) was reduced in H67A and H247A mutants, with site B less affected. The H9A mutation decreased Zn2+ binding at the lower-affinity site, establishing His9 as a site B ligand. Zn2+ binding to HSA and H9A was compromised by palmitate, consistent with FA binding affecting site A. 13C-NMR experiments confirmed that the FA2-KO mutations prohibited FA binding at site FA2. Zn2+ binding to the FA2-KO mutant was unaffected by myristate, suggesting binding at FA2 is solely responsible for inhibition. Molecular dynamics studies identified the steric obstruction exerted by bound FA in site FA2, which impedes the conformational change from open (FA-loaded) to closed (FA-free) states, required for Zn2+ to bind at site A. The successful targeting of the FA2 site will aid functional studies exploring the interplay between circulating FA levels and plasma Zn2+ speciation in health and disease.

Changes in fibrin clot properties in patients after Roux-en-Y gastric bypass surgery.

Background: Obesity is a complex condition associated with prothrombotic fibrin networks that are resistant to fibrinolysis. Altered fibrin clot properties enhance cardiovascular risk and associate with a poorer prognosis following acute ischemic events. Bariatric surgery is commonly employed to improve cardiometabolic outcomes in individuals with obesity. However, the effects of this surgical intervention on fibrin clot properties have not been comprehensively studied. Objectives: To examine fibrin clot and lysis parameters in Roux-en-Y gastric bypass (RYGB) patients before and after surgery. Methods: The fibrin clot properties of 32 individuals living with obesity before and 9 months after RYGB surgery were determined using turbidimetric analysis. Correlation and regression analyses were used to identify relationships between clot properties and anthropomorphic and clinical measures. Results: RYGB surgery resulted in a significant reduction in adiposity-associated anthropometric measures as well as improvements in glycemia and lipid profile. Clot maximum absorbance was reduced from 0.43 ± 0.11 at baseline to 0.29 ± 0.10 at 9 months postsurgery (P < .0001), while fibrin clot lysis time failed to show a difference. The change in maximum absorbance was not caused by alterations in fibrinogen levels, while plasminogen activator inhibitor-1 concentration was significantly increased after surgery from 10,560 ± 6681 pg/mL to 15,290 ± 6559 pg/mL (P = .009). Correlation and regression analyses indicated that maximum absorbance was influenced by markers of adiposity as well as glycated hemoglobin and high-sensitivity C-reactive protein concentrations. Conclusion: RYGB surgery led to a decrease in the maximum absorbance of the fibrin clot. Values of maximum absorbance were associated with measures of glycemic control and inflammation. In contrast to previous reports, fibrin clot lysis time was not affected after surgery.

Recent Advances in Metalloproteomics.

Interactions between proteins and metal ions and their complexes are important in many areas of the life sciences, including physiology, medicine, and toxicology. Despite the involvement of essential elements in all major processes necessary for sustaining life, metalloproteomes remain ill-defined. This is not only owing to the complexity of metalloproteomes, but also to the non-covalent character of the complexes that most essential metals form, which complicates analysis. Similar issues may also be encountered for some toxic metals. The review discusses recently developed approaches and current challenges for the study of interactions involving entire (sub-)proteomes with such labile metal ions. In the second part, transition metals from the fourth and fifth periods are examined, most of which are xenobiotic and also tend to form more stable and/or inert complexes. A large research area in this respect concerns metallodrug-protein interactions. Particular attention is paid to separation approaches, as these need to be adapted to the reactivity of the metal under consideration.

Zn2+ Differentially Influences the Neutralisation of Heparins by HRG, Fibrinogen, and Fibronectin.

For coagulation to be initiated, anticoagulant glycosaminoglycans (GAGs) such as heparins need to be neutralised to allow fibrin clot formation. Platelet activation triggers the release of several proteins that bind GAGs, including histidine-rich glycoprotein (HRG), fibrinogen, and fibronectin. Zn2+ ions are also released and have been shown to enhance the binding of HRG to heparins of a high molecular weight (HMWH) but not to those of low molecular weight (LMWH). The effect of Zn2+ on fibrinogen and fibronectin binding to GAGs is unknown. Here, chromogenic assays were used to measure the anti-factor Xa and anti-thrombin activities of heparins of different molecular weights and to assess the effects of HRG, fibrinogen, fibronectin, and Zn2+. Surface plasmon resonance was also used to examine the influence of Zn2+ on the binding of fibrinogen to heparins of different molecular weights. Zn2+ had no effect on the neutralisation of anti-factor Xa (FXa) or anti-thrombin activities of heparin by fibronectin, whereas it enhanced the neutralisation of unfractionated heparin (UFH) and HMWH by both fibrinogen and HRG. Zn2+ also increased neutralisation of the anti-FXa activity of LMWH by fibrinogen but not HRG. SPR showed that Zn2+ increased fibrinogen binding to both UFH and LMWH in a concentration-dependent manner. The presented results reveal that an increase in Zn2+ concentration has differential effects upon anticoagulant GAG neutralisation by HRG and fibrinogen, with implications for modulating anti-coagulant activity in plasma.

Health service needs and perspectives of a rainforest conserving community in Papua New Guinea's Ramu lowlands: a combined clinical and rapid anthropological assessment with parallel treatment of urgent cases.

OBJECTIVES: Determine community needs and perspectives as part of planning health service incorporation into Wanang Conservation Area, in support of locally driven sustainable development. DESIGN: Clinical and rapid anthropological assessment (individual primary care assessments, key informant (KI) interviews, focus groups (FGs), ethnography) with treatment of urgent cases. SETTING: Wanang (pop. c189), a rainforest community in Madang province, Papua New Guinea. PARTICIPANTS: 129 villagers provided medical histories (54 females (f), 75 males (m); median 19 years, range 1 month to 73 years), 113 had clinical assessments (51f, 62m; median 18 years, range 1 month to 73 years). 26 ≥18 years participated in sex-stratified and age-stratified FGs (f<40 years; m<40 years; f>40 years; m>40 years). Five KIs were interviewed (1f, 4m). Daily ethnographic fieldnotes were recorded. RESULTS: Of 113 examined, 11 were 'well' (a clinical impression based on declarations of no current illness, medical histories, conversation, no observed disease signs), 62 (30f, 32m) were treated urgently, 31 referred (15f, 16m), indicating considerable unmet need. FGs top-4 ranked health issues concorded with KI views, medical histories and clinical examinations. For example, ethnoclassifications of three ((A) 'malaria', (B) 'sotwin', (C) 'grile') translated to the five biomedical conditions diagnosed most ((A) malaria, 9 villagers; (B) upper respiratory infection, 25; lower respiratory infection, 10; tuberculosis, 9; (C) tinea imbricata, 15) and were highly represented in declared medical histories ((A) 75 participants, (B) 23, (C) 35). However, 29.2% of diagnoses (49/168) were limited to one or two people. Treatment approaches included plant medicines, stored pharmaceuticals, occasionally rituals. Travel to hospital/pharmacy was sometimes undertaken for severe/refractory disease. Service barriers included: no health patrols/accessible aid post, remote hospital, unfamiliarity with institutions and medicine costs. Service introduction priorities were: aid post, vaccinations, transport, perinatal/birth care and family planning. CONCLUSIONS: This study enabled service planning and demonstrated a need sufficient to acquire funding to establish primary care. In doing so, it aided Wanang's community to develop sustainably, without sacrificing their forest home.

The most polyphagous insect herbivore? Host plant associations of the Meadow spittlebug, Philaenus spumarius (L.).

A comprehensive list of all known host plant species utilised by the Meadow Spittlebug (Philaenus spumarius (L.)) is presented, compiled from published and unpublished sources. P. spumarius feeds on 1311 host plants in 631 genera and 117 families. This appears, by a large margin, to be the greatest number of host species exploited by any herbivorous insect. The Asteraceae (222 species) and Rosaceae (110) together account for 25% of all host species. The Fabaceae (76) and Poaceae (73), are nearly tied for third and fourth place and these four families, combined with the Lamiaceae (62), Apiaceae (50), Brassicaceae (43) and Caprifoliaceae (34), comprise about half of all host species. Hosts are concentrated among herbaceous dicots but range from ferns and grasses to shrubs and trees. Philaenus spumarius is an "extreme polyphage", which appears to have evolved from a monophage ancestor in the past 3.7 to 7.9 million years. It is also the primary European vector of the emerging plant pathogen Xylella fastidiosa. Its vast host range suggests that it has the potential to spread X. fastidiosa among multiple hosts in any environment in which both the spittlebug and bacterium are present. Fully 47.9% of all known hosts were recorded in the Xylella-inspired BRIGIT citizen science P. spumarius host survey, including 358 hosts new to the documentary record, 27.3% of the 1311 total. This is a strong demonstration of the power of organized amateur observers to contribute to scientific knowledge.

Structural and biochemical characterisation of Co2+-binding sites on serum albumins and their interplay with fatty acids.

Serum albumin-Co2+ interactions are of clinical importance. They play a role in mediating the physiological effects associated with cobalt toxicity and are central to the albumin cobalt binding (ACB) assay for diagnosis of myocardial ischemia. To further understand these processes, a deeper understanding of albumin-Co2+ interactions is required. Here, we present the first crystallographic structures of human serum albumin (HSA; three structures) and equine serum albumin (ESA; one structure) in complex with Co2+. Amongst a total of sixteen sites bearing a cobalt ion across the structures, two locations were prominent, and they relate to metal-binding sites A and B. Site-directed mutagenesis and isothermal titration calorimetry (ITC) were employed to characterise sites on HSA. The results indicate that His9 and His67 contribute to the primary (putatively corresponding to site B) and secondary Co2+-binding sites (site A), respectively. The presence of additional multiple weak-affinity Co2+ binding sites on HSA was also supported by ITC studies. Furthermore, addition of 5 molar equivalents of the non-esterified fatty acid palmitate (C16:0) reduced the Co2+-binding affinity at both sites A and B. The presence of bound myristate (C14:0) in the HSA crystal structures provided insight into the fatty acid-mediated structural changes that diminish the affinity of the protein toward Co2+. Together, these data provide further support for the idea that ischemia-modified albumin corresponds to albumin with excessive fatty-acid loading. Collectively, our findings provide a comprehensive understanding of the molecular underpinnings governing Co2+ binding to serum albumin.

Artificial light impairs local attraction to females in male glow-worms.

The negative effects of artificial lighting at night (ALAN) on insects are increasingly recognised and have been postulated as one possible cause of declines in insect populations. Yet, the behavioural mechanisms underpinning ALAN effects on insects remain unclear. ALAN interferes with the bioluminescent signal female glow-worms use to attract males, disrupting reproduction. To determine the behavioural mechanisms that underpin this effect of ALAN, we quantified the effect of white illumination on males' ability to reach a female-mimicking LED within a Y-maze. We show that as the intensity of illumination increases, the proportion of males reaching the female-mimicking LED declines. Brighter illumination also increases the time taken by males to reach the female-mimicking LED. This is a consequence of males spending more time: (i) in the central arm of the Y-maze; and (ii) with their head retracted beneath their head shield. These effects reverse rapidly when illumination is removed, suggesting that male glow-worms are averse to white light. Our results show that ALAN not only prevents male glow-worms from reaching females, but also increases the time they take to reach females and the time they spend avoiding exposure to light. This demonstrates that the impacts of ALAN on male glow-worms extend beyond those previously observed in field experiments, and raises the possibility that ALAN has similar behavioural impacts on other insect species that remain undetected in field experiments.

The role of Zn2+ in shaping intracellular Ca2+ dynamics in the heart.

Increasing evidence suggests that Zn2+ acts as a second messenger capable of transducing extracellular stimuli into intracellular signaling events. The importance of Zn2+ as a signaling molecule in cardiovascular functioning is gaining traction. In the heart, Zn2+ plays important roles in excitation-contraction (EC) coupling, excitation-transcription coupling, and cardiac ventricular morphogenesis. Zn2+ homeostasis in cardiac tissue is tightly regulated through the action of a combination of transporters, buffers, and sensors. Zn2+ mishandling is a common feature of various cardiovascular diseases. However, the precise mechanisms controlling the intracellular distribution of Zn2+ and its variations during normal cardiac function and during pathological conditions are not fully understood. In this review, we consider the major pathways by which the concentration of intracellular Zn2+ is regulated in the heart, the role of Zn2+ in EC coupling, and discuss how Zn2+ dyshomeostasis resulting from altered expression levels and efficacy of Zn2+ regulatory proteins are key drivers in the progression of cardiac dysfunction.

Magnesium Deficiency and Cardiometabolic Disease.

Magnesium (Mg2+) has many physiological functions within the body. These include important roles in maintaining cardiovascular functioning, where it contributes to the regulation of cardiac excitation-contraction coupling, endothelial functioning and haemostasis. The haemostatic roles of Mg2+ impact upon both the protein and cellular arms of coagulation. In this review, we examine how Mg2+ homeostasis is maintained within the body and highlight the various molecular roles attributed to Mg2+ in the cardiovascular system. In addition, we describe how nutritional and/or disease-associated magnesium deficiency, seen in some metabolic conditions, has the potential to influence cardiac and vascular outcomes. Finally, we also examine the potential for magnesium supplements to be employed in the prevention and treatment of cardiovascular disorders and in the management of cardiometabolic health.

Investigating Native Metal Ion Binding Sites in Mammalian Histidine-Rich Glycoprotein.

Mammalian histidine-rich glycoprotein (HRG) is a highly versatile and abundant blood plasma glycoprotein with a diverse range of ligands that is involved in regulating many essential biological processes, including coagulation, cell adhesion, and angiogenesis. Despite its biomedical importance, structural information on the multi-domain protein is sparse, not least due to intrinsically disordered regions that elude high-resolution structural characterization. Binding of divalent metal ions, particularly ZnII, to multiple sites within the HRG protein is of critical functional importance and exerts a regulatory role. However, characterization of the ZnII binding sites of HRG is a challenge; their number and composition as well as their affinities and stoichiometries of binding are currently not fully understood. In this study, we explored modern electron paramagnetic resonance (EPR) spectroscopy methods supported by protein secondary and tertiary structure prediction to assemble a holistic picture of native HRG and its interaction with metal ions. To the best of our knowledge, this is the first time that this suite of EPR techniques has been applied to count and characterize endogenous metal ion binding sites in a native mammalian protein of unknown structure.

Optimised plasma sample preparation and LC-MS analysis to support large-scale proteomic analysis of clinical trial specimens: Application to the Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) trial.

PURPOSE: Robust, affordable plasma proteomic biomarker workflows are needed for large-scale clinical studies. We evaluated aspects of sample preparation to allow liquid chromatography-mass spectrometry (LC-MS) analysis of more than 1500 samples from the Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) trial of adults with type 2 diabetes. METHODS: Using LC-MS with data-independent acquisition we evaluated four variables: plasma protein depletion, EDTA or citrated anti-coagulant blood collection tubes, plasma lipid depletion strategies and plasma freeze-thaw cycles. Optimised methods were applied in a pilot study of FIELD participants. RESULTS: LC-MS of undepleted plasma conducted over a 45 min gradient yielded 172 proteins after excluding immunoglobulin isoforms. Cibachrome-blue-based depletion yielded additional proteins but with cost and time expenses, while immunodepleting albumin and IgG provided few additional identifications. Only minor variations were associated with blood collection tube type, delipidation methods and freeze-thaw cycles. From 65 batches involving over 1500 injections, the median intra-batch quantitative differences in the top 100 proteins of the plasma external standard were less than 2%. Fenofibrate altered seven plasma proteins. CONCLUSIONS AND CLINICAL RELEVANCE: A robust plasma handling and LC-MS proteomics workflow for abundant plasma proteins has been developed for large-scale biomarker studies that balance proteomic depth with time and resource costs.

Bird preferences for fruit size, but not color, vary in accordance with fruit traits along a tropical elevational gradient.

Birds constitute one of the most important seed dispersal agents globally, especially in the tropics. The feeding preferences of frugivorous birds are, therefore, potentially of great ecological importance. A number of laboratory-based and observational studies have attempted to ascertain the preferences of certain bird species for certain fruit traits. However, little attention has been paid to community-wide preferences of frugivorous birds and the impact this may have on fruit traits on a broader scale. Here, we used artificial fruits of different colors and sizes to investigate community-wide fruit trait preferences of birds at three sites along an elevational gradient in Papua New Guinea. We recorded attack rates on artificial fruits as visible impressions made by a bird's beak during a feeding attempt. We also measured the colors and sizes of real fruits at each site, and the gape widths of frugivorous birds, allowing for comparisons between bird feeding preferences and bird and fruit traits. Regardless of elevation, red and purple fruits were universally preferred to green and attacked at similar rates to one another, despite strong elevational patterns in real fruit color. However, elevation had a significant effect on fruit size preferences. A weak, non-significant preference for large fruits was recorded at 700 m, while medium fruits were strongly preferred at 1700 m and small fruits at 2700 m. These patterns mirror those of both real fruit size and frugivorous bird gape width along the gradient, suggesting the potential for selective pressure of birds on fruit size at different elevations.

Total plasma magnesium, zinc, copper and selenium concentrations in obese patients before and after bariatric surgery.

Obesity enhances the risk of type-2 diabetes, cardiovascular disease and inflammatory conditions and often leads to metal dyshomeostasis, which contributes to the negative health aspects associated with the disease. In severe cases, bariatric surgery can be recommended to achieve sustained weight loss and improvement in health. Here, magnesium, zinc, copper and selenium concentrations were examined in 24 obese patients (7 males; 17 females) before and 9 months after undergoing Roux-en-Y gastric bypass surgery. All patients lost weight over this period, with the mean BMI reducing from 51.2±7.1 kg/m2 to 37.2±5.5 kg/m2. Moreover, whole-blood glycated haemoglobin (HbA1c), as a marker of average glycaemia, was also measured and a correlative analysis of this parameter with metal concentrations performed. Significant alterations in the plasma concentrations of magnesium, zinc (both increased by 13.2% and 25.2% respectively) and copper (decreased by 7.9%) were observed over this period (plasma selenium concentration was unchanged), with BMI values correlating with plasma magnesium (p = 0.004) and zinc (p = 0.022) concentrations. At 9 months post-surgery, an increase in mean zinc/copper ratio was observed (0.86±0.29 compared to 0.63±0.14 pre-surgery). Comparison of whole-blood HbA1c concentrations pre- and post-surgery revealed a reduction from 6.50±1.28% pre-surgery to 5.51±0.49% post-surgery. Differences in plasma HbA1c and magnesium at either pre- and post-surgery correlated significantly, as did HbA1c and magnesium levels when pre- and post-surgery values were analysed together. Collectively, this work reveals that bariatric surgery, in conjunction with lifestyle/dietary changes, lead to improvements in the nutritional status of magnesium, zinc and copper. Furthermore, the observed improvements in magnesium and zinc were associated with weight loss and in the case of magnesium, to better glycaemic control.

Five New Diarylbutyrolactones and Sesquilignans from Saussurea medusa and Their Inhibitory Effects on LPS-induced NO Production.

Five new diarylbutyrolactones and sesquilignans (1A/1B:  - 4: ), including one pair of enantiomers (1A/1B: ), together with 10 known analogues (5:  - 14: ), were isolated from the whole plants of Saussurea medusa. Compound 1: was found to possess an unusual 7,8'-diarylbutyrolactone lignan structure. Separation by chiral HPLC analysis led to the isolation of one pair of enantiomers, (+)-1A: and (-)-1B: . The structures of the new compounds were elucidated by extensive spectroscopic data. All compounds, except compounds 5, 7: and 9: , were isolated from S. medusa for the first time. Moreover, compounds 1:  -  4, 8: and 10:  - 14: had never been obtained from the genus Saussurea previously. Compounds (+)- 1A, 2, 5, 7: , and 9:  - 11: were found to inhibit the lipopolysaccharide (LPS)-induced release of NO by RAW264.7 cells with IC50 values ranging from 10.1 ± 1.8 to 41.7 ± 2.1 µM. Molecular docking and iNOS expression experiments were performed to examine the interactions between the active compounds and the iNOS enzyme.

Periarticular metal hypersensitivity complications of hip bearings containing cobalt-chromium.

Hip joints with bearings composed of cobalt-chromium alloy (metal-on-metal bearings) have been one of the most widely used implants in joint replacement arthroplasty. Unfortunately, these implants can contribute to a complication called aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL), a type IV metal hypersensitivity response around the joint. Consistent with such bearings, increased metal debris can be found in the surrounding fluids and in remote tissues and organs, due to wear and corrosion. It is hypothesized that metal ions released from the prosthesis (including Co2+) can potentially form haptens with proteins such as serum albumin in synovial fluid that in turn elicit ALVAL. Generally, elevated cobalt and chromium levels in synovial fluids may indicate implant failure. However, such measurements cannot be used as a reliable tool to predict the onset of ALVAL. To detect ALVAL, some diagnostic tests, questionnaires and imaging techniques have been used clinically with some success, but a standardized approach is lacking. At present, guidelines for implant usage and patient management are ambiguous and inconsistent across health care authorities. To reduce and better manage the development of ALVAL, further research into the precise molecular mechanism(s) by which ALVAL develops is urgently needed. Identification of diagnostic and prognostic biomarkers for ALVAL is required, as are more standardized guidelines for surgery and patient management.

Changes in plasma free fatty acids in obese patients before and after bariatric surgery highlight alterations in lipid metabolism.

Obesity is a complex disease that increases an individual's risk of developing other diseases and health-related problems. A common feature is dyslipidemia characterized by increased levels of plasma lipids, which include non-esterified fatty acids (NEFAs). The role of NEFAs in obesity-related morbidity is interesting as NEFAs constitute a reservoir of metabolic energy, are principal components of cell membranes and are precursors for signalling molecules. Bariatric surgery promotes sustained weight loss in severely obese patients, reducing the incidence and severity of co-morbidities. In this study we measure changes in circulating NEFA species in plasma samples taken from 25 obese individuals before and 9 months after Roux-en-Y gastric bypass surgery. The mean weight of the cohort reduced by 29.2% from 149.0 ± 25.1 kg pre-surgery to 105.5 ± 19.8 kg post-surgery and the BMI by 28.2% from 51.8 ± 6.3 kg/m2 pre-surgery to 37.2 ± 5.4 kg/m2. Mean glycated haemoglobin (HbA1c) reduced from 6.5 ± 1.3 to 5.5 ± 0.5%, consistent with the intervention leading to improved glycaemic control, particularly in those who were dysglycemic prior to surgery. Total and LDL cholesterol concentrations were markedly reduced following surgery. Concentrations of seven NEFAs were found to decrease 9 months after surgery compared to pre-surgery levels: myristate, palmitoleate, palmitate, linoleate, oleate, stearate and arachidonate. Bariatric surgery led to increased lipogenesis and elongase activity and decreased stearoyl-CoA desaturase 1 activity. This study therefore highlights metabolic changes that take place following gastric bypass surgery in severely obese patients.

Organism-specific differences in the binding of ketoprofen to serum albumin.

Serum albumin is a circulatory transport protein that has a highly conserved sequence and structure across mammalian organisms. Its ligand-binding properties are of importance as albumin regulates the pharmacokinetics of many drugs. Due to the high degree of structural conservation between mammalian albumins, nonhuman albumins such as bovine serum albumin or animal models are often used to understand human albumin-drug interactions. Ketoprofen is a popular nonsteroidal anti-inflammatory drug that is transported by albumin. Here, it is revealed that ketoprofen exhibits different binding-site preferences when interacting with human serum albumin compared with other mammalian albumins, despite the conservation of binding sites across species. The reasons for the observed differences were explored, including identifying ketoprofen binding determinants at specific sites and the influence of fatty acids and other ligands on drug binding. The presented results reveal that the drug-binding properties of albumins cannot easily be predicted based only on a complex of albumin from another organism and the conservation of drug sites between species. This work shows that understanding organism-dependent differences is essential for assessing the suitability of particular albumins for structural or biochemical studies.

Strategies for Therapeutic Amelioration of Aberrant Plasma Zn2+ Handling in Thrombotic Disease: Targeting Fatty Acid/Serum Albumin-Mediated Effects.

The initiation, maintenance and regulation of blood coagulation is inexorably linked to the actions of Zn2+ in blood plasma. Zn2+ interacts with a variety of haemostatic proteins in the bloodstream including fibrinogen, histidine-rich glycoprotein (HRG) and high molecular weight kininogen (HMWK) to regulate haemostasis. The availability of Zn2+ to bind such proteins is controlled by human serum albumin (HSA), which binds 70-85% of plasma Zn2+ under basal conditions. HSA also binds and transports non-esterified fatty acids (NEFAs). Upon NEFA binding, there is a change in the structure of HSA which leads to a reduction in its affinity for Zn2+. This enables other plasma proteins to better compete for binding of Zn2+. In diseases where elevated plasma NEFA concentrations are a feature, such as obesity and diabetes, there is a concurrent increase in hypercoagulability. Evidence indicates that NEFA-induced perturbation of Zn2+-binding by HSA may contribute to the thrombotic complications frequently observed in these pathophysiological conditions. This review highlights potential interventions, both pharmaceutical and non-pharmaceutical that may be employed to combat this dysregulation. Lifestyle and dietary changes have been shown to reduce plasma NEFA concentrations. Furthermore, drugs that influence NEFA levels such as statins and fibrates may be useful in this context. In severely obese patients, more invasive therapies such as bariatric surgery may be useful. Finally, other potential treatments such as chelation therapies, use of cholesteryl transfer protein (CETP) inhibitors, lipase inhibitors, fatty acid inhibitors and other treatments are highlighted, which with additional research and appropriate clinical trials, could prove useful in the treatment and management of thrombotic disease through amelioration of plasma Zn2+ dysregulation in high-risk individuals.