Serum leptin level in women with idiopathic intracranial hypertension

Leptin is a protein secreted by adipose cells which influences regulation of energy balance and body weight. Idiopathic intracranial hypertension (IIH) is recognised as a neurological disorder mainly affecting obese females. The aim of this study was to evaluate the association between IIH and serum leptin level in 15 obese patients and compare the results with those for 16 obese and 15 non-obese women. A significantly higher serum leptin level was found in patients with IIH than in controls (p<0.0001), and this did not correlate with body mass index (BMI). Serum leptin levels were significantly associated with BMI in both control groups (p<0.0006). Additional factors must therefore be involved in the phenomenon of serum leptin increase beyond weight gain. The cause can only be hypothesised, but it seems that the origin is central, probably hypothalamic.

Serum homocysteine, folate, vitamin B12 levels and arterial stiffness in diabetic patients: which of them is really important in atherogenesis?

AIM

Hyperhomocystinaemia is associated with macro- and microangiopathic diabetic complications. However, the role of homocysteine (Hcy), serum folate, and vitamin B12 level in the development of premature vascular damage in type 2 diabetic patients is not clear. The present study was designed to assess the relationship between total Hcy, folate, and vitamin B12 levels and arterial stiffness, an early marker of generalized atherosclerosis.

METHODS

As many as 86 subjects with type 2 diabetes mellitus were studied. All participants were evaluated for glucose, HbA(1C), lipid profile, hs-CRP, endothelin, Hcy, vitamin B12, and folate. Pulse wave velocity (PWV) and augmentation index (AI) were performed as a non-invasive recording and computer analysis of the two artery sites pressure waveform using SphygmoCor (version 7.1, AtCor Medical, Sydney, Australia).

RESULTS

Hcy was significantly positively associated with age, serum creatinine, and vitamin B12 levels. No association between Hcy and folate was observed. The Hcy concentration was significantly positively associated with PWV (r = 0.540, p < 0.0001) and AI (r = 0.390, p < 0.0001). In a general linear model of PWV, Hcy emerged as an independent predictor of PWV even after controlling for age, creatinine, vitamin B12, and folate levels. In a multiple linear regression analysis, the association between Hcy and arterial stiffness was independent of traditional cardiovascular risk factors. Vitamin B12 levels were significantly inversely associated with tHcy (r = - 0.263, p = 0.015) and marginally associated with PWV(r = - 0.212, p = 0.052). Significant associations between folate levels and PWV were not detected.

CONCLUSIONS

The results lend support to the hypothesis that elevated Hcy may have a key role in the development of atherogenesis in diabetic patients. Additionally, vitamin B12 is significantly associated with tHcy concentrations and is identified as a marginally independent correlate of PWV in diabetic patients in the absence of folate deficiency.

Heterogeneity of Lipopolysaccharide as Source of Variability in Bioassays and LPS-Binding Proteins as Remedy

Lipopolysaccharide (LPS), also referred to as endotoxin, is the major component of Gram-negative bacteria's outer cell wall. It is one of the main types of pathogen-associated molecular patterns (PAMPs) that are known to elicit severe immune reactions in the event of a pathogen trespassing the epithelial barrier and reaching the bloodstream. Associated symptoms include fever and septic shock, which in severe cases, might even lead to death. Thus, the detection of LPS in medical devices and injectable pharmaceuticals is of utmost importance. However, the term LPS does not describe one single molecule but a diverse class of molecules sharing one common feature: their characteristic chemical structure. Each bacterial species has its own pool of LPS molecules varying in their chemical composition and enabling the aggregation into different supramolecular structures upon release from the bacterial cell wall. As this heterogeneity has consequences for bioassays, we aim to examine the great variability of LPS molecules and their potential to form various supramolecular structures. Furthermore, we describe current LPS quantification methods and the LPS-dependent inflammatory pathway and show how LPS heterogeneity can affect them. With the intent of overcoming these challenges and moving towards a universal approach for targeting LPS, we review current studies concerning LPS-specific binders. Finally, we give perspectives for LPS research and the use of LPS-binding molecules.

The association between the renin-angiotensin-aldosterone system and arterial stiffness in young healthy subjects

Aldosterone might affect arterial stiffening, in both the short- and long-term. We investigated a possible association between excess aldosterone, reflected by an increased aldosterone : renin ratio (ARR) and pulse wave velocity (PWV) in young healthy adults. In a single-centre study, 60 subjects were evaluated for lipid profile, glucose, hs-CRP, renin and aldosterone. PWV was performed as a simple non-invasive recording and computer analysis of the two artery sites pressure waveform using SphygmoCor (version 7.1, AtCor Medical, Sydney, Australia). The ARR was significantly, positively associated with PWV: r = 0.298, P = 0.02. ARR was not associated with anthropometric variables, blood pressure (BP), metabolic and inflammatory parameters. In conclusion, the ARR was significantly associated with PWV and may exhibit direct effects of aldosterone on the vascular wall, which are not related to changes in conventional cardiovascular risk factors.

Novobiocin-induced anti-proliferative and differentiating effects in melanoma B16

The antibiotic drug novobiocin was evaluated for its anti-tumour properties in B16 melanoma cells. Novobiocin is shown to inhibit melanoma B16 cell proliferation. The anti-proliferative effect was gradually reversible upon removal of novobiocin from the culture medium. Growth inhibition by novobiocin was accompanied by phenotypic alterations, that included morphological changes, lipid accumulation and marked increases in the activities of NADPH cytochrome c reductase and gamma glutamyl transpeptidase. In vivo administration of repeated i.p. doses of novobiocin, to mice implanted with B16 melanoma cells resulted in growth retardation. The combined treatment of the B16 melanoma cells with novobiocin and other chemical inducers of differentiation was examined in a cell growth assay. Novobiocin and sodium butyrate inhibited cell growth in a near additive manner, while combination of novobiocin with the GTP-depleting agents, tiazofurin or mycophenolic acid resulted in a synergistic decrease in cell growth. Our results support the contention further that novobiocin and other differentiating agents might be of potential value in melanoma therapy.

Effect of long-term treatment with risedronate on arterial compliance in osteoporotic patients with cardiovascular risk factors

Accumulating evidence suggests that osteoporosis and coronary artery disease have epidemiologic similarities. Moreover, the anti-atherogenic effects of bisphosphonates have been observed in vitro and in animal models. The present study investigated the effect of risedronate on indices of arterial compliance, serum osteoprotegerin (OPG) level, inflammatory and metabolic parameters in osteoporotic women with cardiovascular risk factors. In an open label, prospective study 68 postmenopausal osteoporotic women were evaluated for the study. Patients received risedronate orally in a dose of 35 mg per week, daily supplements of calcium and cholecalciferol during 6month treatment period. Patients were evaluated for lipid profile, HbA1C, insulin, C-peptide, fibrinogen, hs-CRP and plasma osreoprotegerin. Arterial elasticity was evaluated using pulse wave contour analysis (HDI CR 2000, Eagan, Minnesota). Large artery elasticity index (LAEI) increased from 9.86+/-3.66 to 11.54+/-">+/-3.16 ml/mm HgX10 (p<0.0001) during treatment period. Small artery elasticity index (SAEI) increased from 2.64+/-1.10 to 3.28+/-1.16 ml/mm HgX100 (p<0.0001). Systemic vascular resistance (SVR) decreased from 1876.12+/-457.72 to 1646.12+/-260.17 dyn/s/cm(- 5) (p<0.013). Metabolic parameters did not change during the treatment period. Plasma osteoprotegerin was significantly, positively correlated to SVR at baseline (r=0.36, p=0.045). At the final visit, OPG was marginally inversely associated with LAE (r=- 0.312, p=0.09), and significantly, positively associated with total vascular impedance (r=0.43, p=0.015). In conclusion, prolonged treatment with risedronate improved arterial elasticity of small and large arteries, and decreased SVR. These beneficial vascular effects were not related to changes in cardiovascular risk factors and may be attributed to direct effects of risedronate on the vascular wall.

Dimethylthiourea inhibition of B16 melanoma growth and induction of phenotypic alterations; relationship to ATP levels

1,3 Dimethylthiourea (DMTU) has previously been shown by us to inhibit the growth of melanoma cells and to induce phenotypic alterations in these cells, including ultrastructural alterations of mitochondria. These findings raised the possibility that impaired mitochondrial function might be involved in mediating the effect of DMTU on cell growth and phenotypic expression. The present study indicates that DMTU as well as another growth inhibitory methylurea derivative, tetramethylurea (TMU) significantly decrease ATP content in the B16 melanoma cell line. 1,3 Dimethylurea (1,3DMU) and 1,1 dimethylurea (1,1DMU) which are poor growth inhibitors, do not reduce ATP content significantly. Altered energy metabolism in the DMTU-treated cells is reflected by inhibition of the activity of cytochrome c oxidase and by increased lactate levels. A cell line selected for resistance to growth inhibition by DMTU was shown to be completely resistant to induction of phenotypic alterations by DMTU. These cells possess high lactate levels, high ATP content and a somewhat decreased Na/K ATPase activity as compared to wild type B16 F10 cells. 1,3 DMTU treatment of the resistant cells leads to a decrease in the activity of the mitochondrial enzyme cytochrome c oxidase, similar to its effect on the wild type B16 F10 cells. DMTU also reduces ATP content moderately in the resistant cells. However, the levels of ATP do not decrease beyond those found in untreated B16 F10 wild type cells. Taken together the results suggest that decreased ATP content might be involved, at least partially, in mediating the effects of DMTU on B16 melanoma cell growth and phenotypic expression.

An active DNA-based nanoprobe for photoacoustic pH imaging

We report an active DNA construct capable of probing pH through a photoacoustic (PA) ratiometric analysis approach. Our nanoprobe enables different PA readout in tissue mimicking phantoms in the range between pH 6.8 to 7.8 at physiologically relevant sodium concentrations. Thus, it represents a promising platform to probe pH values relevant to the tumor microenvironment using PA.

Recovering What Matters: High Protein Recovery after Endotoxin Removal from LPS-Contaminated Formulations Using Novel Anti-Lipid A Antibody Microparticle Conjugates

Endotoxins or lipopolysaccharides (LPS), found in the outer membrane of Gram-negative bacterial cell walls, can stimulate the human innate immune system, leading to life-threatening symptoms. Therefore, regulatory limits for endotoxin content apply to injectable pharmaceuticals, and excess LPS must be removed before commercialization. The majority of available endotoxin removal systems are based on the non-specific adsorption of LPS to charged and/or hydrophobic surfaces. Albeit effective to remove endotoxins, the lack of specificity can result in the unwanted loss of essential proteins from the pharmaceutical formulation. In this work, we developed microparticles conjugated to anti-Lipid A antibodies for selective endotoxin removal. Anti-Lipid A particles were characterized using flow cytometry and microscopy techniques. These particles exhibited a depletion capacity > 6 ×103 endotoxin units/mg particles from water, as determined with two independent methods (Limulus Amebocyte Lysate test and nanoparticle tracking analysis). Additionally, we compared these particles with a non-specific endotoxin removal system in a series of formulations of increasing complexity: bovine serum albumin in water < insulin in buffer < birch pollen extracts. We demonstrated that the specific anti-Lipid A particles show a higher protein recovery without compromising their endotoxin removal capacity. Consequently, we believe that the specificity layer integrated by the anti-Lipid A antibody could be advantageous to enhance product yield.

The effect of the locus pstB on phosphate binding in the phosphate specific transport (PST) system of Escherichia coli

The periplasmic phosphate binding protein is a product of the phoS gene and is an essential component of the phosphate specific transport (PST) system, which mediates Pi uptake in Escherichia coli. The binding of Pi to periplasmic protein(s) and the kinetic parameters of Pi uptake were studied in phoT and pstB mutants of E. coli. These mutants are impaired in Pi uptake but have a periplasmic Pi-binding protein whose Pi-binding capacity was estimated by the retention kinetics. The Pi-binding activity in two pstB mutants was found to be weaker as compared to phoT9 and the wild type. The KD values for Pi binding to periplasmic protein were determined by equilibrium dialysis. In the pstB mutants the KD value was found to be 9-31 times higher than the values obtained for the wild type and the phoT mutant. The apparent Km values for Pi uptake in one pstB mutant is 14.3 times higher than in the wild type. Vmax of the mutant is 8.3 times lower that of the wild type. The data indicate that pstB, an essential gene of the PST transport system, is promoting the binding capacity of the Pi-binding protein.

Generation of Endotoxin-Specific Monoclonal Antibodies by Phage and Yeast Display for Capturing Endotoxin

Endotoxin, a synonym for lipopolysaccharide (LPS), is anchored in the outer membranes of Gram-negative bacteria. Even minute amounts of LPS entering the circulatory system can have a lethal immunoactivating effect. Since LPS is omnipresent in the environment, it poses a great risk of contaminating any surface or solution, including research products and pharmaceuticals. Therefore, monitoring LPS contamination and taking preventive or decontamination measures to ensure human safety is of the utmost importance. Nevertheless, molecules used for endotoxin detection or inhibition often suffer from interferences, low specificity, and low affinity. For this reason, the selection of new binders that are biocompatible, easy to produce, and that can be used for biopharmaceutical applications, such as endotoxin removal, is of high interest. Powerful techniques for selecting LPS-binding molecules in vitro are display technologies. In this study, we established and compared the selection and production of LPS-specific, monoclonal, human single-chain variable fragments (scFvs) through two display methods: yeast and phage display. After selection, scFvs were fused to a human constant fragment crystallizable (Fc). To evaluate the applicability of the constructs, they were conjugated to polystyrene microbeads. Here, we focused on comparing the functionalized beads and their LPS removal capacity to a polyclonal anti-lipid A bead. Summarized, five different scFvs were selected through phage and yeast display, with binding properties comparable to a commercial polyclonal antibody. Two of the conjugated scFv-Fcs outperformed the polyclonal antibody in terms of the removal of LPS in aqueous solution, resulting in 265 times less residual LPS in solution, demonstrating the potential of display methods to generate LPS-specific binding molecules.