The effect of recentrifugation of serum separator tubes on concentration of serum analytes

In clinical laboratories, sometimes there is a need to recentrifuge the original tubes ("clot" tubes) in order to better clarify and clean the serum or plasma for further analysis. Also, the original tubes are recentrifuged to ensure there is an adequate volume of serum or plasma for multiple repeating or different tests, and/or to run additional tests that are ordered hours after the original analysis was completed. In our practice, we have encountered that recentrifugation of original tubes, including those with gel separators, does slightly change the concentration of analytes. Although there are two reports on the effect of recentrifugation on serum potassium concentration [1, 2], to the best of our knowledge there are no other studies to show the impact of re-centrifugation on the concentrations of multiple analytes that are routinely measured as part of "metabolic panel". This study investigated the effect of recentrifugation on the concentrations of glucose, sodium, potassium, chloride, BUN, creatinine, bicarbonate, calcium, phosphorus, and magnesium.

A blood-based screening tool for Alzheimer's disease that spans serum and plasma: findings from TARC and ADNI

CONTEXT

There is no rapid and cost effective tool that can be implemented as a front-line screening tool for Alzheimer's disease (AD) at the population level.

OBJECTIVE

To generate and cross-validate a blood-based screener for AD that yields acceptable accuracy across both serum and plasma.

DESIGN, SETTING, PARTICIPANTS

Analysis of serum biomarker proteins were conducted on 197 Alzheimer's disease (AD) participants and 199 control participants from the Texas Alzheimer's Research Consortium (TARC) with further analysis conducted on plasma proteins from 112 AD and 52 control participants from the Alzheimer's Disease Neuroimaging Initiative (ADNI). The full algorithm was derived from a biomarker risk score, clinical lab (glucose, triglycerides, total cholesterol, homocysteine), and demographic (age, gender, education, APOE*E4 status) data.

MAJOR OUTCOME MEASURES

Alzheimer's disease.

RESULTS

11 proteins met our criteria and were utilized for the biomarker risk score. The random forest (RF) biomarker risk score from the TARC serum samples (training set) yielded adequate accuracy in the ADNI plasma sample (training set) (AUC = 0.70, sensitivity (SN) = 0.54 and specificity (SP) = 0.78), which was below that obtained from ADNI cerebral spinal fluid (CSF) analyses (t-tau/Aβ ratio AUC = 0.92). However, the full algorithm yielded excellent accuracy (AUC = 0.88, SN = 0.75, and SP = 0.91). The likelihood ratio of having AD based on a positive test finding (LR+) = 7.03 (SE = 1.17; 95% CI = 4.49-14.47), the likelihood ratio of not having AD based on the algorithm (LR-) = 3.55 (SE = 1.15; 2.22-5.71), and the odds ratio of AD were calculated in the ADNI cohort (OR) = 28.70 (1.55; 95% CI = 11.86-69.47).

CONCLUSIONS

It is possible to create a blood-based screening algorithm that works across both serum and plasma that provides a comparable screening accuracy to that obtained from CSF analyses.

Redox-proteomics of the effects of homogentisic acid in an in vitro human serum model of alkaptonuric ochronosis

Alkaptonuria (AKU) is a rare inborn error of metabolism associated with a deficient activity of homogentisate 1,2-dioxygenase (HGO), an enzyme involved in tyrosine and phenylalanine metabolism. Such a deficiency leads to the accumulation of homogentisic acid (HGA) and its oxidized/polymerized products in connective tissues, where melanin-like pigments accumulate (ochronosis). Ochronosis involves especially joints, where an ochronotic arthropathy develops. Little is known on the molecular mechanisms leading to ochronosis and ochronotic arthropathy in AKU. Previous works of ours showed that HGA in vitro propagates oxidative stress through its conversion into benzoquinone acetate (BQA). We hence used an in vitro model consisting of human serum treated with HGA and evaluated the activities of glutathione related anti-oxidant enzymes and levels of compounds indexes of oxidative stress. Proteomics and redox-proteomics were used to identify oxidized proteins and proteins more likely able to bind BQA. Overall, we found that the production of ochronotic pigment in HGA-treated serum is accompanied by lipid peroxidation, decreased activity of the enzyme glutathione peroxidase and massive depletion of thiol groups, together with increased protein carbonylation and thiol oxidation. We also found that BQA was likely to bind carrier proteins and naturally abundant serum proteins, eventually altering their chemico-physical properties. Concluding, our work points towards a critical importance of thiol compounds in counteracting HGA- and BQA- mediated stress in AKU, so that future research for disease biomarkers and pharmacological treatments for AKU and ochronosis will be more easily addressed.

Influence of common preanalytical variations on the metabolic profile of serum samples in biobanks

A blood pre-centrifugation delay of 24 h at room temperature influenced the proton NMR spectroscopic profiles of human serum. A blood pre-centrifugation delay of 24 h at 4°C did not influence the spectroscopic profile as compared with 4 h delays at either room temperature or 4°C. Five or ten serum freeze-thaw cycles also influenced the proton NMR spectroscopic profiles. Certain common in vitro preanalytical variations occurring in biobanks may impact the metabolic profile of human serum.

Effect of host portal and peripheral sera fractions on cell proliferation of Schistosoma mansoni schistosomules

Schistosomules of Schistosoma mansoni were incubated in medium containing hamster (highly susceptible host) portal or peripheral venous serum, or rat (poorly susceptible host) portal or peripheral venous serum or their fractions in the presence of bromodeoxyuridine (BrdU) in order to determine effects of host sera on cell proliferation. BrdU labeling indices (BLIs) were significantly increased in the presence of portal (33.05±0.70, p<0.05), but not in peripheral serum (19.1±0.85, p>0.05) of hamsters, compared to schistosomules cultured in presence of control medium (18.96±0.66). This stimulatory effect was substantially reproduced by fraction 4 (31.03±0.69, p>0.05) separated from hamster portal serum. In contrast, no significant differences were observed in the BLIs in rat portal or peripheral sera as well as their fractions when compared to control medium. Taken together, it was concluded that portal serum of hamster and its fraction which includes a low molecular weight protein (20 kDa) enhanced cell proliferation of S. mansoni schistosomules. This could explain the localization and preference of S. mansoni schistosomules and worms to portal-mesenteric venous system.

Full range characterization of the Raman spectra of organs in a murine model

Raman spectroscopy is a minimally-invasive optical technique with great potential for in vivo cancer detection and disease diagnosis. However, there is no systematic study of the Raman spectra from different organs to date. We measured and characterized the Raman spectra eighteen naïve mouse organs in a broad frequency range of 700 to 3100 cm⁻¹. The peaks of generic proteins and lipids appeared in Raman spectra of all organs. Some organs like bone, teeth, brain and lung had unique Raman peaks. The autofluorescence was strong in liver, spleen, heart, and kidney. These results suggest that organ specific Raman probe design and specific data processing strategies are required in order to get the most useful information.

Optimized dextran-polyethylenimine conjugates are efficient non-viral vectors with reduced cytotoxicity when used in serum containing environments

Polyethylenimine (PEI) is a cationic polymer that is an efficient transfection reagent marred by high toxicity and a susceptibility to aggregate in the presence of serum. Dextran is a biodegradable natural polysaccharide that can be used to reduce the toxicity of PEI and increase its stability in the presence of serum. In this study, small branched PEI units (800/2000 Da) were attached to dextran (Dex; 15/100-200 kDa) to form dextran-polyethylenimine (Dex-PEI) conjugates. The Dex-PEI conjugates were then tested as a gene carrier in the model HEK293 cell line. Dex-PEI conjugates displayed significantly lower cytotoxicity than PEI (25k). Both Dex-PEI and PEI efficiently delivered firefly luciferase encoded plasmid DNA (pDNA) to the HEK293 cells. Dex-PEI resulted in moderately lower transfection efficiencies than PEI 25k when the transfection was carried out in media without serum for 4h. However, in the presence of serum, which more accurately predicts the anticipated environment of non-viral vectors in vivo, Dex-PEI and unmodified PEI generated similar transfection efficiencies when incubated with the cells for 4h. When the incubation time of the vectors was increased to 48h, significantly higher transfection efficiencies were generated by Dex-PEI in comparison to PEI. Turbidity measurements showed that complexes formed between plasmid DNA and unmodified PEI were more susceptible to aggregation in serum-containing media than complexes formed from pDNA and Dex-PEI. Dex-PEI conjugates are therefore believed to have greater potential for translational applications because of lower cytotoxicity characteristics and improved stability in serum containing environments.

MetSign: a computational platform for high-resolution mass spectrometry-based metabolomics

Data analysis in metabolomics is currently a major challenge, particularly when large sample sets are analyzed. Herein, we present a novel computational platform entitled MetSign for high-resolution mass spectrometry-based metabolomics. By converting the instrument raw data into mzXML format as its input data, MetSign provides a suite of bioinformatics tools to perform raw data deconvolution, metabolite putative assignment, peak list alignment, normalization, statistical significance tests, unsupervised pattern recognition, and time course analysis. MetSign uses a modular design and an interactive visual data mining approach to enable efficient extraction of useful patterns from data sets. Analysis steps, designed as containers, are presented with a wizard for the user to follow analyses. Each analysis step might contain multiple analysis procedures and/or methods and serves as a pausing point where users can interact with the system to review the results, to shape the next steps, and to return to previous steps to repeat them with different methods or parameter settings. Analysis of metabolite extract of mouse liver with spiked-in acid standards shows that MetSign outperforms the existing publically available software packages. MetSign has also been successfully applied to investigate the regulation and time course trajectory of metabolites in hepatic liver.

Ratio analysis nuclear magnetic resonance spectroscopy for selective metabolite identification in complex samples

Metabolite identification in the complex NMR spectra of biological samples is a challenging task due to significant spectral overlap and limited signal-to-noise. In this study we present a new approach, RANSY (ratio analysis NMR spectroscopy), which identifies all the peaks of a specific metabolite on the basis of the ratios of peak heights or integrals. We show that the spectrum for an individual metabolite can be generated by exploiting the fact that the peak ratios for any metabolite in the NMR spectrum are fixed and proportional to the relative numbers of magnetically distinct protons. When the peak ratios are divided by their coefficients of variation derived from a set of NMR spectra, the generation of an individual metabolite spectrum is enabled. We first tested the performance of this approach using one-dimensional (1D) and two-dimensional (2D) NMR data of mixtures of synthetic analogues of common body fluid metabolites. Subsequently, the method was applied to (1)H NMR spectra of blood serum samples to demonstrate the selective identification of a number of metabolites. The RANSY approach, which does not need any additional NMR experiments for spectral simplification, is easy to perform and has the potential to aid in the identification of unknown metabolites using 1D or 2D NMR spectra in virtually any complex biological mixture.

Hydrogen sulfide inhibits proliferation and release of IL-8 from human airway smooth muscle cells

Hydrogen sulfide (H(2)S) is synthesized intracellularly by the enzymes cystathionine-γ-lyase and cystathionine-β-synthase (CBS), and is proposed to be a gasotransmitter with effects in modulating inflammation and cellular proliferation. We determined a role of H(2)S in airway smooth muscle (ASM) function. ASM were removed from resection or transplant donor lungs and were placed in culture. Proliferation of ASM was induced by FCS and the proinflammatory cytokine, IL-1β. Proliferation of ASM and IL-8 release were measured by bromodeoxyuridine incorporation and ELISA, respectively. Exposure of ASM to H(2)S "donors" inhibited this proliferation and IL-8 release. Methemoglobin, a scavenger of endogenous H(2)S, increased DNA synthesis induced by FCS and IL-1β. In addition, methemoglobin increased IL-8 release induced by FCS, but not by IL-1β, indicating a role for endogenous H(2)S in these systems. Inhibition of CBS, but not cystathionine-γ-lyase, reversed the inhibitory effect of H(2)S on proliferation and IL-8 release, indicating that this is dependent on CBS. CBS mRNA and protein expression were inhibited by H(2)S donors, and were increased by methemoglobin, indicating that CBS is the main enzyme responsible for endogenous H(2)S production. Finally, we found that exogenous H(2)S inhibited the phosphorylation of extracellular signal-regulated kinase-1/2 and p38, which could represent a mechanism by which H(2)S inhibited cellular proliferation and IL-8 release. In summary, H(2)S production provides a novel mechanism for regulation of ASM proliferation and IL-8 release. Therefore, regulation of H(2)S may represent a novel approach to controlling ASM proliferation and cytokine release that is found in patients with asthma.

Attenuation of IGF-I receptor signaling inhibits serum-induced proliferation of prostate cancer cells

OBJECTIVE

Several studies showed that high serum levels of insulin-like growth factor-I (IGF-I) correlate with an increased risk for prostate cancer, although the causal role of IGF-I remains to be established. In this study, we addressed the role of IGF-I as a serum factor on the growth of two androgen-independent cell lines (Du145 and PC3) and one androgen-dependent cell line (LNCaP).

DESIGN

We investigated the effects of a blocking antibody against the IGF-I receptor (αIR3) on DNA synthesis in prostate cancer cells cultured in the presence of recombinant human IGF-I or normal human serum (NHS).

RESULTS

We show that in all three prostate cancer cell lines, NHS exerts a markedly stronger stimulating effect on DNA synthesis than IGF-I, and that the effect of NHS can be completely abrogated by an antibody against the IGF-I receptor (αIR3). Using pharmacological inhibitors of the two canonical IGF-I receptor signaling pathways, we show that the phosphatidylinositol-3'-kinase (PI3K) and the Mek-Erk pathways are not required for the stimulating effect of NHS.

CONCLUSION

Our observations indicate that the stimulating effect of NHS is completely dependent on IGF-I receptor signaling transduction and that IGF-I stimulates DNA synthesis in prostate cancer cells in strong synergy with other serum factors. We speculate that the role of other serum factors could explain the discrepancy between the results observed in different animal models to study the function of IGF-I in prostate cancer.

The role of poly(ethylene glycol) brush architecture in complement activation on targeted microbubble surfaces

Complement fixation to surface-conjugated ligands plays a critical role in determining the fate of targeted colloidal particles after intravenous injection. In the present study, we examined the immunogenicity of targeted microbubbles with various surface architectures and ligand surface densities using a flow cytometry technique. Targeted microbubbles were generated using a post-labeling technique with a physiological targeting ligand, cyclic arginine-glycine-asparagine (RGD), attached to the distal end of the poly(ethylene glycol) (PEG) moieties on the microbubble surface. Microbubbles were incubated in human serum, washed and then mixed with fluorescent antibodies specific for various serum components. We found that complement C3/C3b was the main human serum factor to bind in vitro to the microbubble surface, compared to IgG or albumin. We also investigated the effect of PEG brush architecture on C3/C3b fixation to the microbubble surface. RGD peptide was able to trigger a complement immune response, and complement C3/C3b fixation depended on microbubble size and RGD peptide surface density. When the targeting ligand was attached to shorter PEG chains that were shielded by a PEG overbrush layer (buried-ligand architecture), significantly less complement activation was observed when compared to the more traditional exposed-ligand motif. The extent of this protective role by the PEG chains depended on the overbrush length. Taken together, our results confirm that the buried-ligand architecture may significantly reduce ligand-mediated immunogenicity. More generally, this study illustrates the use of flow cytometry and microbubbles to analyze the surface interactions between complex biological media and surface-engineered biomaterials.

[The change of serum vascular endothelial growth factor and matrix metalloproteinases-9 in proliferative hemangioma treated with propranolol]

OBJECTIVE

To study the level of serum vascular endothelial growth factor, matrix metalloproteinases-9 in the proliferative hemangioma before and after propranolol treatment.

METHODS

The serum VEGF, MMP-9 was detected with ELISA assay before treatment and after 4 weeks and 8 weeks of propranolol treatment. The relationship between the serum VEGF, MMP-9 and the prognosis was analyzed.

RESULTS

The serum VEGF (295.4 +/- 158.1) pg/ml was high before treatment, then decreased after 4 weeks and 8 weeks of treatment (255.7 +/- 130.4) pg/ml, (224.2 +/- 120.6) pg/ml. The serum VEGF was significantly lower after 8 weeks of treatment (P < 0.05). The serum MMP-9 was also decreased after treatment, showing a positive relationship with VEGF.

CONCLUSIONS

Propranolol can treat the proliferative hemangioma through decreasing the serum VEGF and MMP-9.

[Lipid composition of cells and low-density lipoproteins in blood serum of humans and some vertebrates species]

To investigate interaction of atherogenic low-density lipoproteins (LDL) with erythrocytic membrane, the content of lipid components in blood cells and serum LDL was studied in human in norm (donors) and in 12 species of vertebrates (the mammals non-predisposed to atherosclerosis - birds and fish). Lipid composition of blood cells and LDL was analyzed also in patients with pathologies: ischemic heart disease (IHD), bronchial asthma (BA), and chronic obstructive bronchitis (COB), and in 2 species of mammals predisposed to atherosclerosis, in whose blood LDL predominates. The content of lipids in cells and LDL of the studied vertebrates has been found to depend on their taxonomy and the clear trends both to an increase of the cholesterol content and to a decrease if the phosphatidylcholine level in patients, particu- larly with IHD, and on a rise of the ratio of the content of the more saturated sphingomyelin and cholesterol to the less saturated phosphatidylcholine from the lower to the higher organisms, including humans (donors). The highest levels of free cholesterol in blood cells, of total cholesterol in LDL, and of ration of the cholesterol/phosphatidylcholine content have been revealed in patients, especially with 1HB, and in the mammals predisposed to atherosclerosis, i. e., in representatives with predominance of blood LDL, unlike donors and the mammals resistant to atherosclerosis. The highest parameters of lipid components were determined in cells and LDL inhuman with IHD. The lipid LDL composition affects directly the composition and ratio of lipids in blood cells.

Serum-nutrient starvation induces cell death mediated by Bax and Puma that is counteracted by p21 and unmasked by Bcl-x(L) inhibition

The cyclin-dependent kinase inhibitor p21 (p21WAF1/Cip1) is a multifunctional protein known to promote cell cycle arrest and survival in response to p53-dependent and p53 independent stimuli. We herein investigated whether and how it might contribute to the survival of cancer cells that are in low-nutrient conditions during tumour growth, by culturing isogenic human colorectal cancer cell lines (HCT116) and breast cancer cell lines in a medium deprived in amino acids and serum. We show that such starvation enhances, independently from p53, the expression of p21 and that of the pro-apoptotic BH3-only protein Puma. Under these conditions, p21 prevents Puma and its downstream effector Bax from triggering the mitochondrial apoptotic pathway. This anti-apoptotic effect is exerted from the cytosol but it is unrelated to the ability of p21 to interfere with the effector caspase 3. The survival function of p21 is, however, overcome by RNA interference mediated Bcl-x(L) depletion, or by the pharmacological inhibitor ABT-737. Thus, an insufficient supply in nutrients may not have an overt effect on cancer cell viability due to p21 induction, but it primes these cells to die, and sensitizes them to the deleterious effects of Bcl-x(L) inhibitors regardless of their p53 status.

Differences between human plasma and serum metabolite profiles

BACKGROUND

Human plasma and serum are widely used matrices in clinical and biological studies. However, different collecting procedures and the coagulation cascade influence concentrations of both proteins and metabolites in these matrices. The effects on metabolite concentration profiles have not been fully characterized.

METHODOLOGY/PRINCIPAL FINDINGS

We analyzed the concentrations of 163 metabolites in plasma and serum samples collected simultaneously from 377 fasting individuals. To ensure data quality, 41 metabolites with low measurement stability were excluded from further analysis. In addition, plasma and corresponding serum samples from 83 individuals were re-measured in the same plates and mean correlation coefficients (r) of all metabolites between the duplicates were 0.83 and 0.80 in plasma and serum, respectively, indicating significantly better stability of plasma compared to serum (p = 0.01). Metabolite profiles from plasma and serum were clearly distinct with 104 metabolites showing significantly higher concentrations in serum. In particular, 9 metabolites showed relative concentration differences larger than 20%. Despite differences in absolute concentration between the two matrices, for most metabolites the overall correlation was high (mean r = 0.81±0.10), which reflects a proportional change in concentration. Furthermore, when two groups of individuals with different phenotypes were compared with each other using both matrices, more metabolites with significantly different concentrations could be identified in serum than in plasma. For example, when 51 type 2 diabetes (T2D) patients were compared with 326 non-T2D individuals, 15 more significantly different metabolites were found in serum, in addition to the 25 common to both matrices.

CONCLUSIONS/SIGNIFICANCE

Our study shows that reproducibility was good in both plasma and serum, and better in plasma. Furthermore, as long as the same blood preparation procedure is used, either matrix should generate similar results in clinical and biological studies. The higher metabolite concentrations in serum, however, make it possible to provide more sensitive results in biomarker detection.

Comparison of blood serum peptide enrichment methods by Tricine SDS-PAGE and mass spectrometry

Characterisation of blood serum peptides can provide valuable information on physiological and pathological processes. However, the analysis of raw serum samples by MS results in the identification of a limited number of peptides. In order to improve sensitivity, many peptide enrichment methods have been proposed during the last ten years. Here, we present a comparison of fractionation methods aimed to simplify analysis of small proteins and peptides in blood serum, one of the most promising sources of putative biomarkers. Specifically, three methods based on ultrafiltration, differential precipitation, and peptide ligand libraries (ProteoMiner) were evaluated for the enrichment of peptides and low molecular weight proteins, as demonstrated by Tricine SDS-PAGE and subsequent LC-MS/MS (GeLC-MS/MS). As a result, differential solubilisation (DS) allowed the identification of the highest number of peptides. Moreover, the DS method enabled also the quantitative comparison of samples, producing fundamental information in biomarker discovery approaches.

Disulfide bond prolongs the half-life of therapeutic peptide-GLP-1

The multiple physiological characterization of glucagon-like peptide-1 (GLP-1) makes it a promising drug candidate for the therapy of type 2 diabetes. However, the half-life of GLP-1 is short in vivo due to rapid degradation by dipeptidyl peptidase-IV (DPP-IV) and renal clearance. This indicates that the stabilization of GLP-1 is critical for its utility in drug development. In this study, we developed a cluster of GLP-1 homodimeric analogs, which fused the mutated GLP-1 monomer by an intra-disulfide bridge. The stabilities of the GLP-1 homodimeric analogs were investigated and the physiological functions of the analogs were compared with those of wild-type GLP-1 in rats and human serum. Single dose glucose tolerance test was performed to investigate the administration frequency which satisfied the efficient glucose regulatory in rats. Multiple dose glucose tolerance tests were employed also to study the long-acting anti-diabetic activity of GLP-1 homodimeric analog. The results indicated that the GLP-1 homodimeric analog (hdGLP1G10C) remarkably raised the biological half-life of GLP-1; also HDGLP1G10C showed better glucose tolerance and higher HbA(1c) reduction than GLP-1 in rodents. Based upon the results in this study, it was suggested that hdGLP1G10C prolonged the stability of GLP-1 and retained the biological activity of GLP-1. The improved physiological characterization of hdGLP1G10C makes it as possible potent anti-diabetic drug in the treatment of type 2 diabetes mellitus.

A novel GLP-1 analog exhibits potent utility in the treatment of type 2 diabetes with an extended half-life and efficient glucose clearance in vivo

The multiple physiological characterizations of glucagon-like peptide-1 (GLP-1) make it a promising drug candidate for the therapy of type 2 diabetes. However, the half-life of GLP-1 is short in vivo due to degradation by dipeptidyl peptidase-IV (DPP-IV) and renal clearance. Therefore, the stabilization of GLP-1 is critical for its utility in drug development. Based on our previous research, a GLP-1 analog that contained an intra-disulfide bond exhibited a prolonged biological half-life. In this study, we improved upon previous analogs with a novel GLP-1 analog that contained a tryptophan cage-like sequence for an improved binding affinity to the GLP-1 receptor. The binding capacities and the stabilities of GLP715a were investigated, and the physiological functions of the GLP715a were compared to those of the wild-type GLP-1 in animals. The results demonstrated that the new GLP-1 analog (GLP715a) increased its biological half-life to approximately 48h in vivo; GLP715a also exhibited a higher binding affinity to the GLP-1 receptor than the wild-type GLP-1. The increased binding capacity of GLP715a to its receptor resulted in a quick response to glucose administration. The long-acting anti-diabetic property of GLP715a was revealed by its increased glucose tolerance, higher HbA(1c) reduction, more efficient glucose clearance and quicker insulin stimulation upon glucose administration compared to the wild-type GLP-1 in rodents. The improved physiological characterizations of GLP715a make it a possible potent anti-diabetic drug in the treatment of type 2 diabetes mellitus.

Effects of thermal treatments on protein adsorption of Co-Cr-Mo ASTM-F75 alloys

Post-manufacturing thermal treatments are commonly employed in the production of hip replacements to reduce shrinkage voids which can occur in cast components. Several studies have investigated the consequences of these treatments upon the alloy microstructure and tribological properties but none have determined if there are any biological ramifications. In this study the adsorption of proteins from foetal bovine serum (FBS) on three Co-Cr-Mo ASTM-F75 alloy samples with different metallurgical histories, has been studied as a function of protein concentration. Adsorption isotherms have been plotted using the surface concentration of nitrogen as a diagnostic of protein uptake as measured by X-ray photoelectron spectroscopy. The data was a good fit to the Langmuir adsorption isotherm up to the concentration at which critical protein saturation occurred. Differences in protein adsorption on each alloy have been observed. This suggests that development of the tissue/implant interface, although similar, may differ between as-cast (AC) and heat treated samples.

Hypoglycemic activity of Erythrina variegata leaf in streptozotocin-induced diabetic rats

CONTEXT

Erythrina variegata Linn. (Fabaceae), commonly known as Tiger's Claw, is a thorny deciduous tree grown in tropical and subtropical regions of Eastern Africa, Southern Asia, and Northern Australia. In India, its leaves are traditionally used for diabetes mellitus.

OBJECTIVE

To evaluate the hypoglycemic activity of methanol extract of E. variegata leaf (MEEV) in streptozotocin (STZ)-induced diabetic Wistar rats.

MATERIALS AND METHODS

Hyperglycemia was induced in rats by single intraperitoneal injection of STZ (55 mg/kg body weight). Three days after STZ induction, the hyperglycemic rats were treated with MEEV orally at the doses of 300, 600, and 900 mg/kg body weight daily for 21 days. Glibenclamide (1 mg/kg, orally) was used as reference drug. The fasting blood glucose levels were measured on every 7th day during the 21 days of treatment. Serum biochemical parameters including lipid content were estimated.

RESULTS AND DISCUSSION

MEEV at the doses of 300, 600, and 900 mg/kg orally significantly (P < 0.01) and dose-dependently reduced and normalized blood glucose levels as compared to that of STZ control group; the dose 900 mg/kg being the most potent showing complete normalization of blood glucose levels. Serum biochemical parameters including lipid profile were significantly (P < 0.01) restored toward normal levels in META-treated rats as compared to STZ control animals.

CONCLUSION

This study concludes that E. variegata leaf demonstrated promising hypoglycemic action in STZ-induced diabetic rats substantiating its ethnomedicinal use.

[Clinical significance of glycosylated serum protein in patients with diabetic nephropathy]

OBJECTIVE

To explore the relations between fasting blood glucose (FBG), glycosylated hemoglobin A1c (HbA1c) and glycosylated serum protein (GSP).

METHODS

FBG, HbA1c and GSP were measured in 303 patients with diabetic nephropathy and in 167 non-diabetic patients with comparable baseline data, and the correlations between FBG, HbA1c and GSP were analyzed.

RESULTS

GSP levels were significantly higher in patients with diabetic nephropathy than in the non-diabetic patients (P<0.01). In patients with diabetic nephropathy, GSP levels were found to positively correlate to FBG (r=0.606) and HbA1c (r=0.733).

CONCLUSION

Patients with diabetic nephropathy show strong correlations between FBG, HbA1c and GSP. GSP detection is convenient, stable, and practical in evaluating the average FBG over a short term, which reduces the interference by FBG fluctuations in conventional blood glucose monitoring.

Functionalized micromachines for selective and rapid isolation of nucleic acid targets from complex samples

The transport properties of single-strand DNA probe-modified self-propelling micromachines are exploited for "on-the-fly" hybridization and selective single-step isolation of target nucleic acids from "raw" microliter biological samples (serum, urine, crude E. coli lysate, saliva). The rapid movement of the guided modified microrockets induces fluid convection, which enhances the hybridization efficiency, thus enabling the rapid and selective isolation of nucleic acid targets from untreated samples. The integration of these autonomous microrockets into a lab-on-chip device that provides both nucleic acid isolation and downstream analysis could thus be attractive for diverse applications.

Serum response factor controls CYLD expression via MAPK signaling pathway

Tumor suppressor gene CYLD is a deubiquitinating enzyme which negatively regulates various signaling pathways by removing the lysine 63-linked polyubiquitin chains from several specific substrates. Loss of CYLD in different types of tumors leads to either cell survival or proliferation. In this study we demonstrate that lack of CYLD expression in CYLD−/− MEFs increases proliferation rate of these cells compared to CYLD+/+ in a serum concentration dependent manner without affecting cell survival. The reduced proliferation rate in CYLD+/+ in the presence of serum was due to the binding of serum response factor (SRF) to the serum response element identified in the CYLD promoter for the up-regulation of CYLD levels. The serum regulated recruitment of SRF to the CYLD promoter was dependent on p38 mitogen-activated protein kinase (MAPK) activity. Elimination of SRF by siRNA or inhibition of p38 MAPK reduced the expression level of CYLD and increased cell proliferation. These results show that SRF acts as a positive regulator of CYLD expression, which in turn reduces the mitogenic activation of serum for aberrant proliferation of MEF cells.

Effects of long-term vitamin K(1) (phylloquinone) or vitamin K(2) (menaquinone-4) supplementation on body composition and serum parameters in rats

Vitamin K is a cofactor for γ-glutamyl carboxylase, which is an essential enzyme for the γ-carboxylation of vitamin K-dependent proteins such as osteocalcin and matrix Gla protein. Although it has been suggested that vitamin K plays an important role in the improvement of bone metabolism, the relationship between dietary vitamin K intake and bone metabolism has not been thoroughly investigated. Moreover, vitamin K is thought to have other actions beyond influencing the γ-carboxylation status. In the present study, we examined the effects of the long-term addition of phylloquinone (PK) or menaquinone-4 (MK-4) to a control diet on bone mineral density, bone strength, body composition, and serum parameters in rats. A total of 23 female Sprague-Dawley strain rats (6 weeks old) were divided into three groups: basic control diet group, PK diet (PK: 600mg/kg diet) group, and MK diet (MK-4: 600mg/kg diet) group. Three months after starting the experimental diet, the addition of PK to the basic control diet significantly increased the bone mineral density (BMD) of the femur (p<0.05). In the MK group, there was no significant difference in the BMD of the femur. However, two types of bone strength parameter: the minimum cross-sectional moment of inertia and the polar moment of inertia, were significantly higher in the MK group than in the control (p<0.05, respectively). Furthermore, the femoral bone parameters (the width, dry weight and ash weight, and cortical, cancellous, trabecular, and total bone mineral contents) in the MK group were increased significantly compared with the control. Interestingly, the addition of PK or MK-4 significantly decreased the total fat accumulation (p<0.01 and p<0.05, respectively), and serum triglycerides were reduced by 48% in the PK group and 29% in the MK group compared with the control. There were no significant differences in the levels of serum calcium, phosphorus, alkaline phosphatase, growth hormone, insulin-like growth hormone-1, insulin-like growth hormone binding protein-3, and cross-linked N-teleopeptide of type I collagen among the three groups. This is the first study to demonstrate the effect of the long-term addition of PK or MK-4 to the control diet on body composition and serum parameters in an in vivo system using rats. Further studies on the mechanism of vitamin K supplementation in the regulation of bone metabolism would provide valuable data on the prevention of lifestyle-related disorders, including osteoporosis.