Abstract: Heparan sulfate (HS) and heparin (HP) are functionally important glycosaminoglycans, which interact with a plethora of proteins and participate in several cellular events. They form specific proteoglycans, which are ubiquitously distributed at both extracellular and cellular levels. HS and HP chains vary in the sulfation pattern and the degree of C-5 epimerization of d-glucuronic acid to l-iduronic acid. These modifications are not uniformly distributed within the chain, providing functional oligomeric domains interacting specifically with various effective proteins. The utilization of specific lyases and chemical depolymerization are the commonest procedures used for structural analysis. Di- and oligosaccharide composition of HS can be accurately and sensitively determined by HPLC, CE and MS. Ultraviolet detection is satisfactory enough for unsaturated saccharides and pre-column derivatization with fluorophores and detection with laser-induced fluorescence results in even higher sensitivity. Solid-phase assays can also be used for monitoring interactions with other molecules. In this article the biological significance of HS and HP in health and disease as well as the portfolio of analytical methods that may help to a deeper understanding of their roles in various pathological processes is presented. Such methodologies are of crucial importance for disease diagnosis and the design of novel synthetic sugar-based drugs.
Abstract: Cardiovascular disease is the largest cause of death in Western societies and it primarily results from atherosclerosis of large and medium-sized vessels. Atherosclerosis leads to myocardial infarction, when it occurs in the coronary arteries, or stroke, when it occurs in the cerebral arteries. Pathological processes involved in macrovascular disease include the accumulation of lipids which are retained by extracellular matrix (ECM) molecules, especially by the chondroitin sulfate/dermatan sulfate (CS/DS) proteoglycans (CS/DSPGs), such as versican, biglycan and decorin. The sulfation pattern of CS is a key player in protein interactions causing atherosclerosis. Several studies have shown that lipoproteins bind CSPGs via their glycosaminoglycan chains. Galactosaminoglycans, such as CS and DS, bind low density lipoproteins (LDL), affecting the role of these molecules in the arterial wall. In this article, the role of CS and versican in atherosclerosis and hyaluronan in atherogenesis as well as the up to date known mechanisms that provoke this pathological condition are presented and discussed.
Abstract: Bone metastases occur in 20-40% of patients with lung cancer. Recent studies demonstrate a direct antiproliferative effect of 3rd generation bisphosphonates (BPs) on lung tumors, which may influence the survival. Therefore, we examined the clinical impact of zoledronic acid (ZOL; Zometa), a 3rd generation BP, with a focus on the survival, time to progression and pain effect in lung cancer patients with bone metastases. Lung cancer patients (n = 144, Stage IV) with evidence of metastasis bone scan were included. Eighty-seven of 144 experienced bone pain and received ZOL, 4 mg i.v. every 21 days (Group A), whereas the other 57 patients received no ZOL (Group B). All patients were treated with a combination chemotherapy consisted of docetaxel 100 mg/m(2) and carboplatin AUC = 6. It was found that Group A had a statistically significant longer survival (p < 0.01) when compared to Group B. A statistically significant positive correlation was found between the number of cycles of therapy with ZOL and total patient survival (p < 0.01, Pearson correlation) and time to progression (p < 0.01). Pain effect of ZOL had no significant difference between the 2 groups of patients (p > 0.05). Urine N-telopeptide of type I collagen (NTx) levels decreased in patients with NTx < or = 29 nM BCE/mM creatinine at baseline after treatment with ZOL. The results of our study suggest that the addition of ZOL increases overall survival in lung cancer patients with bone metastases. The longer period of receiving ZOL, the better effect on survival and time to progression.
Abstract: Glycosaminoglycans and proteoglycans are macromolecules of the bone and are involved in the assembly, maturation, mineralization, and maintenance of the extracellular matrix. Heterotopic ossification is the rapid development of calcified bone tissue at ectopic sites of the body, mainly in soft tissues that normally do not ossify. The aim of this study was to characterize the molecular profiles of glycosaminoglycans and proteoglycans in normal and heterotopic bone samples to assess whether differences exist between orthotopic and heterotopic bone. Heterotopic bone tissues contained lower amounts of glycosaminoglycans compared to normal femoral bone. Structural analysis of chondroitin sulfate (CS) revealed that both heterotopic and normal femoral bones were composed mainly of 6-sulfated disaccharides. Quantitative differences in the disaccharide composition of CS, such as the decrease of 6-sulfated disaccharides in heterotopic bone with a concurrent increase of 4-sulfated and nonsulfated disaccharides, were found between ectopic bone and normal femoral bone. The proteoglycans decorin and aggrecan were both detected in all bone samples using specific antibodies. The detection of minor amounts of aggrecan in mature human bone, such as femoral bone, as well as in ectopic bone is described for the first time. These results may elucidate the phenomenon of ectopic bone formation and assist in early detection.
Abstract: Hyaluronic acid is a glycosaminoglycan, which is one of the main components of the extracellular matrix, contributes significantly to cell proliferation and migration, and is involved in many physiological and pathological biologic processes, such as the progression of some malignant tumors. Therefore, the determination of its amounts may be of use for monitoring the progress of some diseases and/or as prognostic/diagnostic marker. Hyaluronan has been used for the therapy of osteoarthritis, for ophthalmic and cosmetic surgeries, and is under investigation for numerous other diseases. In this review, after a short introduction to hyaluronan structure and biologic roles, the electrophoretic, chromatographic and solid-phase assays used for determination of its concentration in biologic samples and in drug formulations are presented.
Abstract: The extended research in cancer has identified specific molecules that play important roles in the pathogenesis of the disease. These effectors constitute potent targets for molecular targeted therapy. In breast cancer, receptors tyrosine kinases regulate major cellular events, such as cell proliferation, differentiation, cell adhesion and apoptosis. Additionally, estrogen receptors are essential for breast cancer progression while estrogens are key molecules for breast cancer-related bone disease. In this short review, we focused on the effects of certain inhibitors on the cell growth, signalling molecules and metalloproteinases that implicated in breast cancer and bone metastasis.
Abstract: N-acetylneuraminic acid (Neu5Ac) and N-glycolylneuraminic acid (Neu5Gc) are the dominant sialic acids (Sia) in mammals usually found in the non-reducing terminal of oligosaccharide side chains in glycoproteins and glycolipids. Their expression and distribution pattern have been correlated both with the malignant phenotype and tumor grade of human cancers. The aim of the present study was to determine by reversed-phase HPLC method the amounts of Neu5Ac and Neu5Gc as well as their distribution among the culture media and cell surface of MG-63 and Saos-2 human osteosarcoma cell lines of high and low metastatic potential. It was determined that MG-63 cells produce up to 5-fold more total sialic acid as compared with the Saos 2 cells. Neu5Ac accounts for ca 60% of the total sialic acids secreted by MG-63 cells, whereas Neu5Gc is the predominant sialic acid present on the MG-63 cell membrane. Saos 2 cells secrete considerable amounts of Neu5Ac to culture media. The obtained data indicate that the human osteosarcoma cells express both forms of Sia-containing glycoconjugates; the differences in the amounts of each of the two major Sia types and their distribution may be related to their differences in morphology and/or metastatic potentials.
Abstract: Tumor progress depends on the proliferation of cancer cells, their interactions with stroma and the proteolytic action of enzymes. Colon cancer is c-kit positive and responsive to the specific tyrosine kinase inhibitor imatinib. We investigated the effect of imatinib on the proliferation of a panel of epithelial colon cancer cell lines in presence and absence of the antimetabolite 5-FU, and the effect of conditioned media (CM) derived from colon stromal fibroblasts with and without previous exposure to imatinib. The effects of imatinib on gene expression of MMPs and TIMPs were also studied. Imatinib effectively inhibited the proliferation of all cell lines, showing IC(50) from 0.3 to 3 microM. Its combination with 5-FU significantly enhances the growth inhibition of the highly tumourigenic HT-29 cells. CM derived from stromal fibroblasts induced the proliferation of the HT-29 cells; this stimulatory effect was abolished upon treatment with CM obtained after exposure of fibroblasts to imatinib. Gene expression of MT1-, MT2-MMP and MMP-7 was also inhibited depending on the cell line, whereas that of TIMP-2 was not affected. CM stimulated MT1-MMP protein expression by HT-29; this stimulatory effect was suppressed in the presence of imatinib. Activation of pro-MMP2 to MMP2 in culture medium of HT-29 treated with CM was increased and this activity was inhibited in presence of imatinib. The obtained data showed that imatinib is a powerful inhibitor of human colon cancer cell growth and effectively suppresses the stromal-induced stimulation of cancer cell growth and activation of proMMP2. Further studies are warranted to evaluate the in vivo effects.
Abstract: Metastatic spread of cancer to bone is a frequent complication in several types of malignancies. Normal bone metabolic process is affected and the imbalance between bone formation and resorption defines bone disease in cancer. Bisphosphonates (BPs) are potent inhibitors of osteoclast-mediated bone resorption that also exhibit antitumor activity. In this short review, we describe the osteolytic mechanisms, the signaling pathways which are involved and the inhibitory mode of action of BPs.
Abstract: Although the biological significance of proteoglycans (PGs) has previously been highlighted in multiple myeloma (MM), little is known about serglycin, which is a hematopoietic cell granule PG. In this study, we describe the expression and highly constitutive secretion of serglycin in several MM cell lines. Serglycin messenger RNA was detected in six MM cell lines. PGs were purified from conditioned medium of four MM cell lines, and serglycin substituted with 4-sulfated chondroitin sulfate was identified as the predominant PG. Flow cytometry and confocal microscopy showed that serglycin was also present intracellularly and on the cell surface, and attachment to the cell surface was at least in part dependent on intact glycosaminoglycan side chains. Immunohistochemical staining of bone marrow biopsies showed the presence of serglycin both in benign and malignant plasma cells. Immunoblotting in bone marrow aspirates from a limited number of patients with newly diagnosed MM revealed highly increased levels of serglycin in 30% of the cases. Serglycin isolated from myeloma plasma cells was found to influence the bone mineralization process through inhibition of the crystal growth rate of hydroxyapatite. This rate reduction was attributed to adsorption and further blocking of the active growth sites on the crystal surface. The apparent order of the crystallization reaction was found to be n=2, suggesting a surface diffusion-controlled spiral growth mechanism. Our findings suggest that serglycin release is a constitutive process, which may be of fundamental biological importance in the study of MM.
Abstract: Sialic acids containing glycoconjugates are very common in human neoplasias and their expression frequently correlates with malignant phenotype and the tumor grade. The majority of tumor markers containing sialic acids in man involve changes in the amount of total sialic acids and in the presence of the two main sialic acid types, Neu5Ac and Neu5Gc, and their derivatives. The aim of the present study was to examine whether malignant mesothelioma cell lines synthesize sialic acid containing glycoconjugates at both the extracellular and cell membrane levels and particularly whether the type and the content of Neu5Ac and Neu5Gc are of biological importance for mesothelioma cell differentiation and evaluation of its prognosis. The study was performed in three human malignant mesothelioma cell lines, two with a fibroblast like phenotype (STAV-FCS and Vester) and one of epithelial differentiation (STAV-AB), which developed from the pleural effusions of patients with malignant mesothelioma and in one human adenocarcinoma cell line (Wart). Neu5Ac and Neu5Gc were determined following a mild hydrolysis step and a sample clean-up procedure. The determination was performed by reversed-phase HPLC after the NeuAc and NeuGc had been converted to per-O-benzoylated derivatives. It was found that Neu5Gc is the major sialic acid in the culture media of all cell lines examined. Molar ratios of Neu5Ac to Neu5Gc showed that Neu5Gc is the predominant sialic acid in the culture medium of the fibroblast-like mesothelioma cells. Neu5Ac is almost undetectable in the cell membrane, whereas Neu5Gc is present in considerable amounts. The obtained results suggest that the type and the content of Neu5Ac and Neu5Gc in culture media are of biological importance for mesothelioma cell differentiation and may be of value in the evaluation of prognosis.
Abstract: In the present study we investigated whether single-strand conformational polymorphism (SSCP) and polyacrylamide gel electrophoresis (PAGE) could be used for the identification of the CFTR DeltaF508 gene mutation, which is commonest in the Greek population. Using DNA from patients carrying this mutation, the appropriate 98 bp region of the CFTR gene was amplified by PCR and the reaction products were analysed by non-radioactive SSCP-electrophoresis using silver staining for band visualization and non-denaturating PAGE to confirm the results. SSCP electrophoretic analysis has been optimized for several parameters in order to achieve the best resolution. Single-strand DNA fragments gave a reproducible pattern of bands, characteristic for the particular mutation. Comparison of the obtain patterns with control samples allowed the detection of the DeltaF508 mutation in the patients studied by SSCP assay and these results were confirmed by the independent method of PAGE. Although SSCP and PAGE can be used for detection of this mutation, PAGE resulted in more distinct patterns than SSCP. It is, therefore, proposed that PAGE can be reliably used for the detection and identification of such a mutation in patients provided that suitable controls are available. The applicability of PAGE to identification of the mutation in carriers, particularly useful for population screening, is also discussed.
Abstract: Oxadiazole homopolymer was found to be a substrate favoring the deposition of hydroxyapatite (HAP) crystals from stable supersaturated solutions at pH 7.40, 37 °C, and 0.15 M NaCl. The second-order dependence of the precipitation of HAP on oxadiazole polymer on the solution supersaturation suggested a surface diffusion controlled mechanism. The surface energy of the HAP nuclei growing on oxadiazole homopolymer was calculated to be 158 mJ m-2 from the dependence of crystal growth rate on the solution supersaturation. The overgrowth of HAP on the polymer was done selectively possibly through active site formation on âNâNâ groups on the macromolecules as confirmed by computational chemistry calculations at 310 K.
Abstract: Metastatic spread of cancer to bone is a frequent complication in several types of malignancies. Normal bone metabolic process is affected and the imbalance between bone formation and resorption defines bone disease in cancer. The major causes of the secondary development of the disease is either the cancer cell itself (metastatic or non-metastatic) or cancer therapies. Early diagnosis of bone metastatic disease is very important for the survival of patients. The dominant disadvantage of imaging techniques used for detection of bone metastases is that they are based on direct anatomic visualization of the metastatic sites on the skeleton and, therefore, are not able to detect metastasis in early stages of the disease. Various biomarkers have been developed and used as indicators of bone formation or resorption. Substantially, these biochemical markers are products, released during the bone metabolic cycle and can be detected in biological samples. The levels of these markers in serum or urine can be correlated with the diagnosis of osseous metastases and the bulk of tumor burden and, in addition, may provide useful data for the patients' follow-up, in order to evaluate the response to various treatments. The biochemical markers often used for monitoring bone formation involve total and bone-specific alkaline phosphatase, osteocalcin and procollagen type I extension propeptides, and those for bone resorption involve urinary calcium, hydroxyproline, hydroxylysine-glycosides, pyridinium crosslinks, crosslinked telopeptides of type I collagen, tartarate-resistant acid phosphatase and bone sialoprotein. For the treatment of bone disease, many therapies have been developed. Bisphosphonates, compounds based on a phosphorous-carbon-phosphorous spine similar to endogenous pyrophosphate, have been successfully used in the treatment of osteoporosis and hypercalcemia of malignancy. They have powerful anti-resorptive activity by suppressing the action of osteoclasts, resulting in the reduction of skeletal events. The analytical methods used for the determination of biomarkers in biological samples as well as the effect of bisphosphonates on the drift of metastatic bone disease are presented in this review.
Abstract: Bone metastases commonly occur in the course of malignant tumor disease. For many years, attempts have been made to identify factors for the management of cancer-induced skeletal complications. Nowadays, synthetic antiresorptive agents are considered to be indispensable for the treatment of cancer-related skeletal events, such as bone metastasis. The most common of these drugs are the bisphosphonates, which represent one of the most significant advances over the last 10 years in the field of supportive care and cancer. They are used for the treatment of cancer-induced hypercalcemia, for the prevention and treatment of postmenopausal osteoporosis, for patients with bone metastases secondary to breast cancer and multiple myeloma. A third-generation bisphosphonate, zolendronate, has been shown to minimize the destructive consequences of bone metastases and to exert a profound effect on tumor-induced osteolysis and tumor growth in bone. Zoledronate is already used for the treatment of hypercalcemia of malignancy, multiple myeloma-related osteolytic events and for patients with documented bone metastases from solid tumors in conjunction with standard antineoplastic therapy. The structure-function activity of the three generations of bisphosphonates developed to date, the in vitro models used for studying their effects on osteoclasts and osteoblasts, as well as the results of clinical trials obtained by the third generation bisphosphonate, zoledronic acid, are presented.
Abstract: Metastatic spread to bone is common in patients with breast cancer and its early detection is required for the better management of these patients. Several biochemical markers of bone remodeling have been recently developed, in order to assess metastatic bone disease with non radiologic methods. The pyridinolin cross-linked amino-terminal telopeptide of type I collagen (NTx) has been measured in serum and urine as a specific marker of bone collagen breakdown, while the bone-isoform of alkaline phosphatase (BAP) has been used to determine bone formation activity. Thirty-three consecutive ambulatory patients with metastatic breast cancer and bone metastases and 31 with extraskeletal metastases only, matched for age and menopausal status, were studied. Serum levels of NTx and BAP were measured by enzyme-linked immunosorbent assays. The diagnostic accuracy of both markers was evaluated by receiver operating characteristic (ROC) analysis. Patients with bone metastases had significantly higher levels of NTx (37.0+/-36.9 nM BCE versus 23.5+/-21.0 nM BCE, P<0.05) and BAP (57.8+/-31.7 U/L versus 36.5+/-28.5 U/L, P<0.01) compared to those without bone metastases. NTx was positively correlated with BAP (R=0.340, P<0.01). The area under the ROC curve was 0.671 for NTx and 0.755 for BAP. Using a cut-off value of 29.7 nM BCE for NTx, specificity and sensitivity were 87.1% and 45.5%, respectively; in the case of BAP, using a cut-off value of 50.6 U/L, the specificity and sensitivity were 90.3% and 54.5%, respectively. In patients not receiving concomitant hormonal treatment, the area under the ROC curve was 0.724 for NTx and 0.822 for BAP; in this subgroup of patients, using a cut-off value of 30.0 nM BCE for NTx, the specificity and sensitivity were 96.2% and 47.1%, respectively, while using a cut-off value of 50.0 U/L for BAP, the corresponding percentages were 92.3% and 70.6%. Although serum NTx and BAP are quite specific, they are not sensitive enough to diagnose bone metastases in patients with advanced breast cancer. Their diagnostic accuracy, however, is considerably enhanced in patients not receiving hormonal therapy.
Abstract: BACKGROUND: Bisphosphonates have an established role in the treatment of bone metastases from a variety of solid tumours. The objective response to anti-resorptive treatment cannot be evaluated by imaging techniques. A number of bone remodelling markers have been associated with bone metastases status; among them, urine and serum levels of N-terminal telopeptide of collagen type I (NTx) seem to have the best diagnostic accuracy. However, serum NTx has not yet been properly evaluated. PATIENTS AND METHODS: Seventy-one consecutive patients with newly diagnosed skeletal metastases were enrolled in this prospective study. All of them were treated with zoledronic acid at 4 mg, every 3 or 4 weeks. Serum NTx and bone-isoform of alkaline phosphatase (BAP) were measured by enzyme-linked immunosorbent assays at baseline and every 2 months thereafter. RESULTS: At baseline, serum NTx and BAP levels were significantly higher in patients with blastic than lytic bone lesions and in those with multiple rather than few bone site involvement. Forty-seven patients were followed for a median period of 139 days. Zoledronic acid resulted in a significant NTx reduction at first and second post-treatment evaluations (mean reduction of 43% at first evaluation); thereafter, mean NTx levels remained suppressed. In contrast, BAP levels did not show any significant changes. Bone disease progression resulted in a significant NTx elevation by an average of 69%. The initial response of NTx to zoledronic acid was correlated with the long-term clinical outcome of bone disease: patients with an initial NTx elevation had a significantly higher rate of bone disease progression compared to those with an initial NTx decline (66.7% versus 18.8%, p=0.001). Extraskeletal disease or bone irradiation did not influence NTx response. CONCLUSION: Serum NTx appears to be a useful marker in monitoring patients with skeletal metastases, as it is correlated with the type and bulk of bone disease and reflects bone disease progression. It is also useful in monitoring bisphosphonate therapy, while the initial response to this therapy seems to bear a prognostic significance for bone disease outcome.
Abstract: The kinetics of vaterite (CaCO3) crystallization in the presence of leucine was investigated by the constant composition technique. The presence of leucine in the supersaturated solution stabilizes this carbonate polymorph by a modulation procedure. The number of ions forming the critical nucleus was found to be two and a surface energy of 23 mJ mâ2 was estimated. The apparent order was found to be 1, typical for a surface diffusion controlled spiral growth mechanism.
Abstract: Bone metastasis is a frequent complication of cancer disease. The metastatic spread of cancer to bone is common to many different malignancies, particularly breast (ca. 73%), prostate (ca. 68%) and lung (ca. 36%) cancers. Metastases to bone cause increased bone resorption both from direct effects of the tumor itself and thought osteoclastic activation. The diagnosis and follow-up of bone metastatic cancer patients usually relies on skeletal X-ray and bone scintigraphy. However, the development of biochemical markers, used as indicators of bone metabolism, provides data useful in the clinical practice. The most important markers for bone remodeling process, bone formation and resorption, are bone-specific alkaline phosphatase (BAP) and N-telopeptide of type I collagen (NTx), respectively. In this report, we applied two solid-phase immunoassays used for the determination of BAP and NTx in serum of breast cancer (BC) post-menopausal women with bone metastasis and healthy individuals. BAP level in patients was found to be 45.72 +/- 12.92 U/l, while the normal range for healthy individuals was 14.2 - 42.7 U/l. The respective level of serum NTx was 19.20 +/- 8.87 nM bone collagen equivalents (BCE) for patients and 15.9 +/- 3.8 nM BCE for healthy women. Correlation of the obtained data showed elevated levels for both markers indicating high rate of bone degradation in breast metastatic cancer.
Abstract: Interaction of basic fibroblast growth factor (bFGF) with heparin/heparan sulfate proteoglycans protects the growth factor against proteolytic degradation and is essential for its cellular activity. Although the structural requirements of heparin and heparan sulfate for the high-affinity binding to bFGF have been extensively examined, studies on intact heparin proteoglycans are limited. In this report, the purity and the binding ability of a heparin proteoglycan-like molecule-the heparin-bovine serum albumin (heparin-BSA) conjugate-was examined using capillary zone electrophoresis (CZE). Furthermore, the affinity of bFGF binding to the heparin-BSA conjugate was studied using an enzyme solid-phase assay. Chondroitin sulfate, dermatan sulfate, hyaluronan, heparan sulfate and variously sulfated disaccharides derived from heparin and heparan sulfate were also studied for their ability to compete with the binding of bFGF to heparin. Heparin-BSA conjugate was synthesized by reductive amination and, following precipitation with 1.5 vols of ethanol-sodium acetate, it was obtained free of contaminating heparin. Heparin-BSA-bFGF conjugate was obtained following incubation of heparin-BSA with bFGF for 2 h at 37 degrees C. Intact heparin, heparin-BSA and heparin-BSA-bFGF conjugates were completely resolved by CZE using 50 mM phosphate, pH 3.5, as operating buffer, reversed polarity (30 kV) and detection at 232 nm. Competitive solid phase assay showed that, among the glycosaminoglycans tested, heparin exhibits the highest affinity binding to bFGF (IC(50) = 6.4 nM). Heparan sulfate showed a lower affinity as compared with that of heparin, whereas all other glycosaminoglycans and heparin/heparan sulfate-derived disaccharides tested showed minute effects. The developed CZE method is rapid and accurate and can be easily used to identify bFGF-interacting heparin preparations of biopharmaceutical importance.
Abstract: Multiple sclerosis (MS) is an autoimmune disease characterized by the production of specific types of immunoglobulins into the central nervous system. These immunoglobulins appear as oligoclonal bands (OCBs) in agarose isoelectric focusing (IEF) of cerebrospinal fluid (CSF). Among the cases with clinically definite MS, up to 95% have oligoclonal IgG bands in their CSF. In this report, we describe a micellar electrokinetic capillary chromatotography (MEKC) method for the separation of CSF and serum proteins. MEKC was performed using 25 mM borate buffer, pH 10, containing 25 mM SDS at 20 kV and normal polarity. High values of repeatability in migration times and of reproducibility in peak areas were obtained (R.S.D. values were less than 2%). Calibration graphs were linear up to 2000 mg L-1. LOQ was 6.5 mg L-1 and LOD determined as a signal to noise ration of 3:1 was 4.5 mg L-1. Analysis of CSF and serum samples from patients with clinical definite MS and healthy individuals demonstrated the presence of two peaks migrating as γ-globulins in the CSF samples of patients. These peaks were absent from controls and the serum of the same patients. Correlation of the data obtained from IEF and MEKC analysis for 25 patients showed that the diagnostic sensitivity and specificity of MEKC were ca 89% and 92% respectively. The obtained results indicate that this MEKC method may be helpful for the diagnosis of multiple sclerosis. Capillary electrophoresis compared to flat bed IEF provides reproducible results, requires shorter analysis time, and allows direct quantitative determination.
Abstract: The kinetics of vaterite (CaCO3) crystallization on calcite in the presence of the aminoacids alanine, glycine, lysine as well as on lysine, polyglycine, polytyrosine and polymethionine was investigated by the constant composition method. The presence of the above mentioned aminoacids stabilizes this calcium carbonate polymorph. The number of ions forming the critical nucleus, the surface energy as well as the apparent growth order for the forming phase was estimated.
Abstract: The use of biprosthetic valves remains limited, due to poor long-term durability, primarily as a result of tissue calcification. Porcine and human cardiac valve leaflets were found to be a substrate favoring the deposition of vaterite crystals from stable supersaturated solution at pH 8.5 at 25°C. The apparent order for vaterite crystallization reaction was found to be n=1, suggesting a surface diffusion controlled mechanism. The crystallization was studied by the constant composition technique, thus making it possible for relatively large amounts of the overgrowth phase to be formed and identified exclusively as vaterite. Analysis of the initial rates of the reaction as a function of the solution supersaturation, according to the classical nucleation theory, yielded a value of 23.4 mJ mâ2 for the surface energy of the growing phase and a three-ion cluster forming the critical nucleus. A novel âin vitroâ anticalcification process based on the treatment of porcine and human heart valves with sodium alginate has been developed. This anticalcification procedure reduced mineralization of porcine and human valves up to 53% and 45%, respectively. Kinetic analysis according to a Langmuir type adsorption isotherm lead to the calculation of an affinity constant Kaff=19.3Ã104molâ1dm3 for the adsorption of sodium alginate to the substrate.
Abstract: Fibrin, a protein endoproduct of blood coagulation was found to be a substrate favoring the deposition of vaterite crystals from stable supersaturated solutions at pH 8.5 and at 25°C. The apparent order for the vaterite crystallization reaction was found to be 1.0±0.1, suggesting a surface diffusion-controlled mechanism. The crystallization was studied by the constant solution composition technique thus making it possible for relatively large amounts of the overgrowth phase to be formed and identified exclusively as vaterite. Fibrin stabilizes this calcium carbonate polymorph, preventing the transformation to the thermodynamically more stable calcite. Analysis of the initial rates of the reaction as a function of the solution supersaturation, according to the classical nucleation theory, yielded a value of 21±1 mJ mâ2 for the surface energy of the growing phase and a three-ion cluster forming the critical nucleus.
