bluuebunny/crossref_metadata_2025 huggingface dataset:
Production of interferon‐β by fibroblast cells on membranes prepared with RGD‐containing peptides
Authors: Higuchi Akon , Takanashi Yasunari , Tsuzuki Nobuya , Asakura Tetsuo , Cho Chong‐Su , Akaike Toshihiro , Hara Mariko
Published: May 2003

The production of interferon‐β by NB1‐RGB fibroblast cells cultured on protein and peptide membranes prepared from silk fibroin, motif peptides of silk fibroin [(AG)n] containing arginine–glycine–aspartic acid (RGD) peptide, and Pronectin™ was investigated. The cell density on various protein and peptide membranes was approximately the same, although the production of interferon‐β depended significantly on the membranes where the cells were cultured. The highest production of interferon‐β was observed when the cells were cultured on (AG)6RGD(AG)7 membranes prepared with hexafluoroacetone (HFA) as the casting solvent. On RGD‐containing peptide membranes more centrally located in the peptides, the cells produced more interferon‐β when the peptide membranes were prepared with HFA as the casting solvent. However, there was no enhanced production of interferon‐β by cells on (AG)6RGD(AG)7 membranes prepared with 9 mol/L LiBr or 4.5 mol/L LiClO4 solution as the casting solvent. Therefore, both the chemical composition and the secondary and higher order structure of the peptide membranes are important for enhanced production of interferon‐β. The blocking of integrin β1 on the cells by anti‐integrin β1 antibody prevented the enhanced production of interferon‐β on (AG)6RGD(AG)7 membranes prepared with HFA. We suggest that the cells must bind to the RGD sequence having the appropriate conformation through their integrin β1 for enhanced production of interferon‐β. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 369–378, 2003
Interfacial kinetics of titanium‐ and cobalt‐based implant alloys in human serum: Metal release and biofilm formation
Authors: Hallab Nadim James , Skipor Anastasia , Jacobs Joshua J.
Published: May 2003

The biocompatibility of metallic implant surfaces is governed in large part by the interfacial kinetics associated with metal release and protein binding. The kinetics of metal release from, and protein binding to, cobalt‐ and titanium‐based implant alloys in human serum were investigated by (1) measuring the temporal release of Cr and Ti into serum from Co‐Cr‐Mo (ASTM F‐75) and Ti implant alloys (Ti‐6Al‐4V: ASTM F136, and commercially pure Ti, cpTi: ASTM F67), respectively; (2) examining the composition of human serum proteins adsorbed onto the surfaces of Co‐ and Ti‐based implant alloys; and (3) identifying the serum proteins associated with the binding of soluble Cr and Ti degradation products. Analysis of metal dissolution kinetics found that Cr was released from Co‐based implant alloy at an order of magnitude higher than Ti was released from Ti‐based implant alloys. Serum became saturated with soluble CR and Ti at levels as high as 3,250 ng/mL Ti from cpTi; 3,750 ng/mL Ti from Ti‐6Al‐4V; and 35,400 ng/mL Cr from Co‐Cr‐Mo degradation. The observation that human serum binds more released metal from Co‐based alloy dissolution was consistent with the observed differences in biofilm composition between the two alloys, where additional serum protein(s) of approximately ≈140 (kDa) molecular weight were detected on Co‐based implant alloy surfaces. However, both Cr and Ti released from Co‐ and Ti‐based alloys exhibited a bimodal binding pattern to both low molecular weight serum protein(s) (<32 kDa), and to higher molecular weight protein(s) in the 180–250 kDa range. Identification of metal alloy–dependent biofilm compositions and dissolution products provides the basis for understanding the bioavailability and bioreactivity of these implant alloys and their degradation products. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 311–318, 2003
Efficacy of glow discharge gas plasma treatment as a surface modification process for three‐dimensional poly (D,L‐lactide) scaffolds
Authors: Chim Harvey , Ong Joo L. , Schantz Jan‐Thorsten , Hutmacher Dietmar W. , Agrawal C. Mauli
Published: May 2003

Gas plasma surface modification of three‐dimensional poly (D,L‐lactide) scaffolds fabricated by a novel vibrating particle fabrication technique was demonstrated to enhance cell adhesion, proliferation, and differentiation over 10 days in culture using human embryonic palatal mesenchyme cells. Characterization of corresponding two‐dimensional treated surfaces revealed decreased contact angle measurements of 54.2 ± 0.6° for treated surfaces compared to 72.3 ± 0.7° for control surfaces (p < 0.05). SEM of treated surfaces revealed increased surface roughness combined with marked pitting and erosion. This may contribute to increased cell adhesion. WST‐1 cell proliferation assay measurements as an index of cell numbers revealed a statistically significant increase in proliferation activity on treated surfaces on days 1 and 4 compared with controls. There was a fivefold increase in WST‐1 activity for both control and treated groups over 10 days. Confocal laser micrographs revealed increased cell numbers on treated specimens throughout all layers of the scaffold, indicating that the glow discharge process enhanced cell proliferation throughout the entire scaffold architecture. Scanning electron micrographs demonstrated increased cell adhesion for treated specimens at the polymer surface most evident after days 1 and 4 of culture. Alkaline phosphatase (ALP)‐specific activity peaked by day 7 for control and treated surfaces, indicating cellular differentiation. There was a trend for increased protein production on the treated specimens compared with controls at the initial time points although the differences were not statistically significant. These results demonstrated that gas plasma surface modification enhances osteoblast‐like cell function in a three‐dimensional scaffold model. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 327–335, 2003
In vitro osteoblast response to anodized titanium and anodized titanium followed by hydrothermal treatment
Authors: Rodriguez R , Kim Kyohan , Ong Joo L.
Published: May 2003

In this study, Titanium (Ti) surfaces were modified using anodization. The electrolyte used for anodization was a mixture of calcium glycerophosphate and calcium acetate. The anodized surfaces were divided into three groups. Hydrothermal treatments were performed on two of the anodized groups for either 2 or 4 h. In vitro osteoblast response to anodized oxide and the hydrothermal treated oxide after anodization was evaluated in this study. Calcium and phosphorus ions were deposited on the Ti oxide during anodization. Anodized surfaces following a 4‐h hydrothermal treatment were observed to promote the growth apatite‐like crystals as compared with anodized surfaces after a 2‐h hydrothermal treatment. Cellular function and onset of mineralization, as indicated by protein production and osteocalcin production, respectively, also were observed as enhanced on hydrothermal‐treated surfaces. It was thus concluded from this study that calcium phosphate and apatite‐like crystals could be deposited on Ti surfaces using anodization and a combination of anodization and hydrothermal treatment. It was also concluded that the phenotypic expression of osteoblast was enhanced by the presence of calcium phosphate or apatite‐like crystals on anodized or hydrothermally treated Ti surfaces. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 352–358, 2003
Mannosylerythritol lipids, yeast glycolipid biosurfactants, are potential affinity ligand materials for human immunoglobulin G
Authors: Im Jae Hong , Yanagishita Hiroshi , Ikegami Toru , Takeyama Yu‐ichiro , Idemoto Yasushi , Koura Nobuyuki , Kitamoto Dai
Published: May 2003

Three mannosylerythritol lipids (MEL‐A, ‐B, and ‐C), yeast glycolipid biosurfactants, were independently attached to poly (2‐hydroxyethyl methacrylate) beads (PHEMA), and the three obtained MEL‐PHEMA composites were examined for their binding affinity to human immunoglobulin G (HIgG). Of the three composites, the composite bearing MEL‐A exhibited the highest binding capacity for HIgG. The binding amount of HIgG increased with increased applied concentration, reaching 106 mg HIgG (per g of composite), with a binding yield of 81%. Interestingly, the protein binding to the composite appeared to follow two different modes (Langmuir type and Freundlich type) depending on the applied concentration. The binding amount of human serum albumin to the composite was much smaller than that of HIgG. The bound human serum albumin, however, had minimal effect on the subsequent binding of HIgG, indicating that the two proteins have different binding sites onto the composite. More significantly, the bound HIgG was efficiently recovered under significantly mild elution conditions: Approximately 90% of the protein was eluted from the composite with phosphate buffer at pH 7. These results indicate that the glycolipid biosurfactant may have great potential as an affinity ligand material for HIgG. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 379–385, 2003
Expression of adhesion molecules and cytokines in vitro by endothelial cells seeded on various polymer surfaces coated with titaniumcarboxonitride
Authors: Lehle Karla , Buttstaedt Johannes , Birnbaum Dietrich E.
Published: May 2003

Although endothelial cell (EC) seeding improves the patency of vascular prostheses, the detachment of adherent ECs after the restoration of circulation remains one of the major obstacles. Polymer surfaces for endothelialization can be optimized. In this study, polyethylene terephthalate (PET), polypropylene (PP), polytetrafluoroethylene (PTFE), polyurethane (PUR), and silicone were coated with a titaniumcarboxonitride (Ti(C,N,O)) layer by a plasma‐assisted chemical vapor deposition process to verify the effect of titanium onto human saphenous vein ECs. Almost confluent EC monolayers were evaluated for 1) proliferation activity and 2) expression of adhesion molecules using cellular enzyme‐linked immunosorbent assay and release of cytokines. The results showed that all titanium‐coated polymers and uncoated PET have no toxic effect on human saphenous vein ECs excepting uncoated PTFE, PP, and silicone. Moreover, growing ECs showed an insignificant decrease in cytokine production and an unessential change in basal expression of adhesion molecules. Tumor necrosis factor‐α–induced response depends on polymer surface: for example, intercellular adhesion molecule‐1 expression decreased. E‐selectin expression was unchanged for culturing ECs on coated PET, PP, and PTFE and reduced for polyurethane and silicone. Vascular cell adhesion molecule‐1 expression was unchanged for coated PUR and silicone and reduced for PET, PP, and PTFE. In summary, titanium‐coating layers promote adhesion of human ECs on polymer vascular grafts with no proinflammatory reaction of ECs. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 393–401, 2003
The proteoglycan contents of the temporomandibular joint disc influence its dynamic viscoelastic properties
Authors: Tanaka Eiji , Aoyama Junko , Tanaka Masao , van Eijden Theo , Sugiyama Masaru , Hanaoka Koichi , Watanabe Mineo , Tanne Kazuo
Published: May 2003

The collagen fibers and proteoglycans in the disc of temporomandibular joint provide resistance to various loadings. Thus far, however, the role of the proteoglycans in determining the viscoelastic properties of the disc has not been investigated. In the present study the hypothesis was tested that the viscoelastic behavior of the disc decreases by the removal of proteoglycans. In 32 bovine discs, dynamic tensile tests with a wide range of frequencies were performed. Before testing, specimens were treated with different concentrations of α‐amylase to remove proteoglycans. As the frequency increased from 0.1 to 100 Hz, the disc became more viscoelastic. Increasing the concentration of α‐amylase significantly decreased its viscoelasticity. It was concluded that proteoglycans play an important role in determining the viscoelastic properties of the disc and, therefore, give the disc a greater capacity for distributing and reducing stresses. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 386–392, 2003
Hydroxylapatite and titanium: Interfacial reactions
Authors: Ergun Celaletdin , Doremus Robert , Lanford William
Published: May 2003

The chemical reactions between hydroxylapatite (HA) and titanium were studied in three different kinds of experiments to increase understanding of how to bond HA to titanium for implant materials. HA powder was bonded to a titanium rod with hot isostatic pressing. Interdiffusion of the HA elements and titanium was found in concentration profiles measured in the electron microprobe. Titanium was vapor‐deposited on sintered HA discs and heated in air; perovskite (CaTiO3) was found on the HA surface with Rutherford backscattering and X‐ray diffraction measurements. Powder composites of HA and titanium and TiO2 were sintered at 1100°C; again, perovskite was a reaction product, as well as β‐Ca3(PO4)2, from decomposition of the HA. These results demonstrate chemical reactions and interdiffusion between HA and TiO2 during sintering, resulting in chemical bonding between HA and titanium. Thus, cracks and weakness at HA–titanium interfaces probably result from mismatch between the coefficients of thermal expansion of these materials. HA composites with other ceramics and different alloys should lead to better thermal matching and better bonding at the interface. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 336–343, 2003
A new quantitative method to evaluate the in vitro bioactivity of melt and sol‐gel‐derived silicate glasses
Authors: Arcos D. , Greenspan D. C. , Vallet‐Regí M.
Published: May 2003

Two melt‐derived glasses (45S5 and 60S) and four sol–gel glasses (58S, 68S, 77S, and 91S) have been synthesized. The activation energy for the silicon release was determined, and a very close correlation was observed between this value and published results of the bioactive behavior of the glasses. This relationship can be explained in terms of the influence of chemical composition, textural properties, and structural density on the silanol group formation and silicon dissolution. These measurements provide a quantitative method to evaluate the in vitro bioactivity of SiO2‐based glasses. Preliminary studies suggest an activation energy gap (Ea) of 0.35–0.5 eV as a boundary between bioactive and nonbioactive glasses. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 344–351, 2003
Calcium‐deficient apatite: A first in vivo study concerning bone ingrowth
Authors: Bourgeois B. , Laboux O. , Obadia L. , Gauthier O. , Betti E. , Aguado E. , Daculsi G. , Bouler J.‐M.
Published: May 2003

Biphasic calcium phosphate (BCP) materials are increasingly used to restore bone loss in surgery. Calcium‐deficient apatites (CDA), the precursors of BCP, are closer in structure to biological apatites and can be associated with therapeutic agents to form drug‐delivery systems. The purpose of this first in vivo study of CDA was to evaluate the osteoconductive properties of two composites, consisting of 40–80 μm granules carried by a cellulose‐derived polymer, used to fill critical size bone defects in rabbit femoral ends. Animals were sacrificed 2 or 3 weeks after implantation. Histomorphometric analysis of scanning electron microscopy implant surface files was performed using gray level threshold that distinguish between bone or materials (white) and noncalcified tissue (black). Quantitative results for new bone formation showed no significant differences between the composites or the implantation periods. However, nearly all of the CDA disappeared early while supporting more extensive bone colonization than biphasic calcium phosphates implanted in the same conditions. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 402–408, 2003
Effects of multigrooved surfaces on fibroblast behavior
Authors: Yoshinari M. , Matsuzaka K. , Inoue T. , Oda Y. , Shimono M.
Published: May 2003

Microgrooves have been investigated as substrates for the control of cell alignment. However, they are relatively too narrow and shallow for controlling the orientation of extracellular matrices (ECM) such as collagen. Multigrooves, a combination of microgrooves and macrogrooves, are expected to be able to control the orientation of both cells and ECM. This study investigated a method for fabricating multigrooves and evaluated fibroblast behavior on these novel surfaces. Multigrooved patterns were fabricated on a gold–alloy metal die, in which 90‐degree V‐shaped microgrooves with a 2‐μm pitch were cut on trapezoidal macrogrooves. The macrogrooves had a 50‐μm ridge width, a 50‐μm wall width, a 50‐μm bottom width, and a 25‐μm depth. The grooves were made by an ultraprecision micromachine using a single crystal diamond. This metal die served as a template for making surface replicas from polystyrene. Microgrooved and smooth polystyrene replicas also were prepared as comparative substrates. Mouse fibroblast L929 cells were cultured in each type of replica substrate for 7 to 21 days. After these periods, the cells were fixed with 2.5% glutaraldehyde, treated with conventional methods, and, finally, observed by SEM. Confocal laser scanning microscopy was performed to investigate ECM formation. The multigrooved metal die exhibited the desired sharp configuration without defects. The dimensional values of the multigrooves on the polystyrene replicas were almost the same as the designed values. The fibroblasts on the multigrooved and microgrooved substrates were aligned parallel to the surface grooves after 7 days of incubation. In contrast to the microgrooved and flat surfaces, a dense extracellular matrix was produced along the multigrooves after 21 days of incubation. These results suggest that multigrooves can control the orientation of ECM as well as cells and thus enhance the production of ECM. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 359–368, 2003
An expression system for the functional analysis of pheromone genes in the tetrapolar basidiomycete Schizophyllum commune
Authors: Gola Susanne , Kothe Erika
Published: May 2003

The investigation of putative pheromone genes of basidiomycetes has been difficult since the small open reading frames are essentially annotated on the basis of a C‐terminal farnesylation signal. In order to identify the functional reading frame, expression of small DNA fragments in the fungus is necessary. The expression system developed in the presented paper allows fusion to the promoter of the tef1 gene encoding the constitutively and highly expressed translation elongation factor EF1α. This system has been shown to be functional using an easily selectable gene, ura1. The application to identification of functional pheromone genes has been shown with the newly detected bap2(4) gene. The Bap2(4) pheromone is the first Bα pheromone gene activating only a single receptor specificity.
Transformations of testosterone and related steroids in Absidia glauca culture
Authors: Huszcza Ewa , Dmochowska‐Gladysz Jadwiga
Published: May 2003

In the following study, the course of transformations of testosterone and its derivatives with an additional C1–C2 double bond and/or 17α‐methyl group or without 19‐methyl group in Absidia glauca culture was investigated. The fungi were observed to hydroxylate these compounds and to oxidise the 17β‐hydroxyl group. The products of 6β, 7α, 7β, 11α, 12β or 15β hydroxylation were obtained. 19‐Nortestosterone was also hydroxylated at the 10β position.

The position and stereochemistry of the introduced hydroxyl group was dependent on the presence of the additional C1–C2 double bond, while hydroxylation at the C‐6β was unaffected. The incubation of testosterone with Absidia glauca gave hydroxyderivatives of androstenedione: 7α‐hydroxyandrostenedione and 6β,11α‐dihydroxyandrostenedione. When 1‐dehydrotestosterone and 1‐dehydro‐17α‐methyltestosterone were used, the products were hydroxylated at 6β, 7β or 15β position while 17α‐methyltestosterone and 19 nortestosterone products were hydroxylated at 6β, 7α, 11α or 12β position. Two metabolites: 6β,11α‐dihydroxyandrostenedione and 6β,12β‐dihydroxy‐17α‐methyltestosterone were dihydroxylated. The presence of 17α‐methyl group in 17α‐methyltestosterone and 1‐dehydro‐17α‐methyltestosterone did not influence the position of hydroxylation.
Physiological and biochemical response of freshwater cryptomonads (Cryptophyceae) to Fe deficiency
Authors: Li Xia , Xiaoming Qin , McKay R. Michael L.
Published: May 2003

Cryptomonads show strong seasonal distribution in lakes yet little is known of their nutrient requirements. In this study, we examined the role of Fe nutrition in the growth and photosynthetic properties of two freshwater cryptomonads (Cryptomonas sp. UTCC 337 and C. erosa UTCC 446). Cryptomonas sp. appeared more tolerant to Fe deprivation compared with C. erosa. Growth rates calculated for Cryptomonas sp. provided 100 nM and 1 000 nM Fe did not vary (0.55 d–1). Only cultures provided 10 nM Fe displayed significantly lower rates of growth (0.26 d–1) and lower cellular yields of chlorophyll. In contrast, cultures of C. erosa provided 10 nM Fe failed to grow, whereas cultures provided 100 nM Fe exhibited a reduced rate of growth (30% reduction) and lower yields of cellular chlorophyll (19% reduction) compared to high Fe (1 000 nM) cultures. Photochemical competency, assessed by measuring DCMU‐enhanced fluorescence, was high for cells of Cryptomonas sp. regardless of the level of Fe provided (Fv/Fm > 0.7). In contrast, photochemical competency was considerably reduced (Fv/Fm = 0.46) for C. erosa provided 100 nM Fe. Consistent with this, levels of the Fe‐containing electron transfer catalyst ferredoxin were reduced by 2.5 times in C. erosa provided 100 nM Fe compared to Fe‐replete cells. By comparison, ferredoxin levels varied only slightly in cells of Cryptomonas sp. provided either 100 nM or 1 000 nM Fe.
Diagnosis of Mycobacterium tuberculosis in cases of pulmonary infections from Jordanian hospitals
Authors: Saadoun Ismail , Nimri Laila , Amer Johnny
Published: May 2003

The aim of this study is to use the diagnostic utility of smear technique for the detection of Mycobacterium tuberculosis in clinical specimens obtained from patients suspected of having pulmonary tuberculosis. A total of 305 respiratory specimens (broncoalveolar lavage, sputum and pleural fluid) were collected from 298 patients having pulmonary infections as bronchitis, tuberculosis, pneumonia and other respiratory diseases. Results revealed that 25 specimens collected from 22 patients were positive (8.2%) by acid fast (AF) smear. Data indicated that the specificity and positive predictive value of the conventional smear assay were 100%, however, the sensitivity of the smear examination was 73.5%. Conventional smear technique actually detected M. tuberculosis in respiratory specimens and it could be applied for early and specific diagnosis of tuberculosis in such patients.
Protective role of certain chemicals against UV‐B‐induced damage in the nitrogen‐fixing cyanobacterium, Nostoc muscorum
Authors: Tyagi R. , Kumar A. , Tyagi M. B. , Jha P. N. , Kumar H. D. , Sinha R. P. , Häder D.P.
Published: May 2003

The protective effects of L‐cysteine, ascorbic acid, reduced glutathione, L‐tryptophan, and sodium pyruvate against UV‐B‐induced damages were studied in the nitrogen‐fixing cyanobacterium, Nostoc muscorum. When added to the culture suspension during UV‐B treatment, these chemicals caused a significant protective effect on survival and growth of the organism. Sodium pyruvate conferred the strongest protection whereas the weakest effect was elicited by tryptophan. A 20 min exposure of a culture suspension to UV‐B completely inactivated nitrogenase activity but the inactivation was strongly prevented by exogenous addition of ascorbic acid or reduced glutathione during UV‐B exposure, and weakly prevented by pyruvate, cysteine and tryptophan. In vivo nitrate reductase activity was not completely lost even after 80 min of UV‐B exposure, and addition of the test chemicals did not confer any significant protection to this enzyme. Whereas 14CO2 uptake was drastically inhibited (78% inhibition) by 30 min exposure to UV‐B in the absence of any test chemical, about 76% activity remained when the UV‐B exposure was given to cultures in the presence of ascorbic acid. These results suggest that the damaging effects of UV‐B are substantially minimized by certain reducing agents, the protective effect being particularly strong on the O2 sensitive enzyme, nitrogenase. Presence of these chemicals in their natural habitat or inside the cells of living organisms may partially protect/repair the damaging effects of UV‐B radiation.
Identification of deoxynivalenol, 3‐acetyldeoxynivalenol, and zearalenone in galactose oxidase‐producing isolates of Fusarium graminearum
Authors: Wilbert Fabricie Marcele , Kemmelmeier Carlos
Published: May 2003

Fusarium graminearum strains are well known for their role as plant pathogens and for their production of mycotoxins, and less known for their secretion of galactose oxidase, a well‐studied and useful enzyme. Three galactose oxidase‐producing isolates of F. graminearum were grown on rice to identify the production of zearalenone and trichothecenes through the use of thin layer chromatography and gas chromatography coupled to mass fragmentation. Detection and identification of deoxynivalenol, 3‐acetyldeoxynivalenol, and zearalenone were acomplished.
Bacillus thuringiensis associated with faeces of the Kerama‐jika, Cervus nippon keramae, a wild deer indigenous to the Ryukyus, Japan
Authors: Ohba Michio , Lee Dong–Hyun
Published: May 2003

Faeces of the Kerama‐jika (Cervus nippon keramae), a wild shika deer indigenous to the Ryukyus, Japan, were examined for the natural occurrence of Bacillus thuringiensis. Of the ten faecal samples tested, seven contained this organism. The frequency of B. thuringiensis was 8.5% among 387 colonies of spore‐forming bacteria belonging to the Bacillus cereus/B. thuringiensis group. Of 33 B. thuringiensis isolates recovered, only one isolate, assigned to the serotype H3abc (serovar kurstaki), exhibited dual toxicity against larvae of the silkworm, Bombyx mori, and the mosquito, Aedes aegypti. All of 32 other isolates were serologically untypable or untestable, and were non‐toxic to larvae of the two insect species.
Isolation, identification and seasonal distrubution of airborne and waterborne fungi in Terkos Lake (Istanbul–Turkey)
Authors: Asan Ahmet , Kirgiz Timur , Sen Burhan , Camur–Elipek Belgin , Guner Utku , Guher Huseyin
Published: May 2003

This paper focuses on isolation and identification of airborne and waterborne fungi from different parts of Terkos Lake located in Istanbul (Turkey). The quantitative and qualitative fungal composition of the air and water of the Lake was surveyed monthly for a year (August 2000–July 2001). Water samples were taken at five different stations at Terkos Lake. Airborne fungal spore levels were estimated by exposing a petri dish containing Rose‐Bengal streptomycin agar medium to air for 15 minutes. A total of 2372 fungal colonies (1032 from air and 1340 water) was counted on 216 petri plates. We isolated twenty mould species belonging to 9 genera.Scopulariopsis brevicaulis, Penicillium expansumandCladosporium herbarumwere the most abundant species (22.0%, 13.4% and 12.9%, respectively).Cladosporium herbarumandsphaerospermumare very common in air samples (29.7% and 27.0%, respectively). Many of the species isolated are rarely in the atmospheric and water environment such asAspergillus nigerandCladosporium variabile. Statistical analysis revealed a positive correlation between total CFUs and a number of environmental factors.
Liquid flow in capillary (electro)chromatography: Generation and control of micro‐ and nanoliter volumes
Authors: Rapp Erdmann , Tallarek Ulrich
Published: May 2003

We describe and discuss instrumental developments in capillary (electro)chromatography which are of particular relevance for generating (and controlling) required volumetric flow rates in the micro‐ and nanoliter range through packed capillaries. Both isocratic and gradient elution are considered. For capillary HPLC this practically involves only commercial instrumentation, with systems based on syringe or piston pumps, but it also realizes the innovative concept of a high‐pressure electrokinetic pump. The numerous systems that have been used to generate electroosmotic flow through chromatographic beds are classified under the following headings: i) basically commercial capillary electrophoresis instruments (adapted for electrochromatography); ii) home‐built configurations; and iii) commercial capillary electrochromatography systems. Concerning the reviewed instrumentation, emphasis is placed on feasibility, automation, as well as system‐inherent delay times and dead volumes.
Onset of sample concentration effects on retention in field‐flow fractionation
Authors: Martin Michel , Feuillebois François
Published: May 2003

In field‐flow fractionation (FFF), when the sample amount is increased, a shift in retention occurs. Positive as well as negative deviations of the retention have been observed, depending on the type of sample and on the experimental conditions. Two concentration effects have been invoked to explain this retention shift: the viscosity effect (the velocity profile of the analyte suspension or solution is modified by the concentration dependence of the viscosity) and the mean distance effect (the mean distance of the analyte molecules or particles to the accumulation wall and the steady state cross‐sectional concentration profile of the analyte are affected by concentration‐dependent interactions between analyte molecules or particles). The general FFF retention equation has been solved in the case where the reciprocal of the viscosity and the FFF analyte‐field interaction parameter, λ, are linearly related to concentration. The two proportionality coefficients involved in these relationships are identified as the intrinsic viscosity and twice the second virial coefficient of the osmotic pressure, respectively. A general expression of the derivative of the analyte average relative velocity, R, with respect to the cross‐sectional average analyte concentration, 〈c〉, has been obtained as a function of these two coefficients, and of λo, the limit of λ for infinite dilution. A survey of retention effects reported in FFF literature for various sample types and FFF methods is presented.
AG+‐HPLC of conjugated linoleic acids on a silica‐based stationary phase. Part IV: A reference stationary phase and retention mechanisms
Authors: Cross Reginald F. , Zackari Henrik
Published: May 2003

In the previous paper on the Ag+‐HPLC of conjugated linoleic acids (CLAs) on a silica‐based stationary phase, we examined the relative retentions of the CLAs, their methyl esters (CLAMEs), and stearic acid. The retention of the CLAs far exceeds the sum of the retention of the CLAMEs and stearic acid. In this paper we isolate the interactions at the silica surface by determining the retentions of the same compounds on the NH4+ cation exchanger that is the precursor to the Ag+ column in the manufacturing process. On the NH4+ column, the CLAMEs are very weakly retained, but the sum of the retentions of the CLAMEs plus stearic acid is equal to that of the CLAs. It was determined that stearic acid is retained to the same degree on both the NH4+ and Ag+ stationary phases. By implication, the CLA carboxylic acid functionality does not interact with Ag+ and thus three‐centre complexes of the Ag+ with the CLA π bonds and carboxyl group do not occur. (Independent supporting evidence is also presented.) A model for CLA retention on the Ag+ stationary phase that explains the synergy of retention is presented. It involves a random arrangement of collapsed Ag+ alkyl sulphonate bonded phase on the silica surface. The nature of retention on the NH4+ stationary phase is also discussed. Partial separation of the CLAs on the NH4+ stationary phase shows that π bond interactions with the silica surface also contribute to the separations of the CLAs, the CLAMEs, and other unsaturated analytes. As was found on the Ag+ column in the absence acetonitrile, normal phase elution occurs and log k′ versus log (% strong solvent) plots for all analytes are linear on the NH4+ column. (Where the specific displacement mechanism of unsaturates from the Ag+ by ACN was present, the log‐linear plots were straight lines.)
Development of a liquid chromatography method for the assay and purity testing of josamycin propionate
Authors: Chepkwony Hezekiah Kibet , Rodriguez Evelio , Govaerts Cindy , Roets Eugène , Hoogmartens Jos
Published: May 2003

A simple, robust, sensitive, and selective liquid chromatography method suitable for the determination of the semi‐synthetic antibiotic, josamycin propionate, and related substances is described. This method utilizes XTerra RP18 5 μm (25 cm×4.6 mm ID) as a stationary phase at 30°C and acetonitrile – 0.2 M ammonium acetate (pH 6.0) – water (51 : 3 : 46, v/v/v) as a mobile phase, delivered at 1.0 mL/min. UV detection is performed at 232 nm. Josamycin propionate is completely separated from the seven related substances of known identity and from at least seven unknown impurities, present in commercial samples. The robustness of the method was evaluated by a full‐factorial experimental design. The LOQ for josamycin propionate was 0.03% and the LOD was 0.01%. For most samples the analysis time is 90 min. Exceptionally, very strongly retained impurities may require an isocratic analysis time of 160 min. In that case, time can be saved by using gradient elution, which needs an analysis time of almost 100 min.
High‐performance liquid chromatography method for analysis of phenolic acids, phenolic aldehydes, and furanic derivatives in brandies. Development and validation
Authors: Canas Sara , Belchior A. Pedro , Spranger M. Isabel , Bruno‐de‐Sousa R.
Published: May 2003

A simple and reproducible HPLC method permitting simultaneous determination of phenolic acids (gallic, vanillic, syringic, and ferulic), phenolic aldehydes (vanillin, syringaldehyde, coniferaldehyde, and sinapaldehyde), and furanic derivatives (furfural, 5‐hydroxymethylfurfural, and 5‐methylfurfural) in brandies was developed and validated. A considerable advantage of this method is the good separation and quantification of the compounds of interest without sample preparation. The method exhibited good linearity, high precision, high sensitivity, and suitable selectivity and specificity over a wide range of concentrations as well as low analytical limits. It can therefore be of a great interest either for scientific research or for routine analysis of brandies, namely in quality control. The analysis of four‐year‐aged brandies shows the real applicability of the method to distinguishing brandies according to the botanical species of the wooden barrel.
Evaluation of the use of microemulsions as eluents in high‐performance liquid chromatography
Authors: El‐Sherbiny Dina Tawfik Mohamed , El‐Ashry Saadia Mohamed , Mustafa Mohamed Ahmed , Abd‐El‐Rahman El‐Emam Ali , Hansen Steen Honoré
Published: May 2003

An overview of the use of microemulsions as eluents in HPLC is given. The separation mechanisms involved are discussed and the technique is compared to solvent modified micellar chromatography as well as to ordinary reversed‐phase HPLC in order to evaluate differences and similarities. The microemulsion systems have been used for the separation of a number of antihypertensives and non steroidal antiinflammatory drug substances as well as for the analysis of bumetanide and acebutolol in plasma and urine. The plasma samples may be injected directly onto the HPLC system after a simple dilution.
Analytical methods for the quantification of free melamine and cyanuric acid in Nylon 6/6,6 co‐polymer
Authors: Hamilton Deanna W. , O'Neal Patrick A.
Published: May 2003

Melamine cyanurate is a salt of melamine and cyanuric acid, which is commonly used as a flame retardant in nylon polymer. Free cyanuric acid and/or melamine in nylon polymer can cause processing problems in molded applications, resulting in brittle parts with low ductility. Analytical methods have been developed to extract free cyanuric acid and melamine from nylon 6/6,6 co‐polymer using an octanesulfonic acid/isopropanol solution. An ion exclusion chromatography method with ultraviolet spectroscopic detection has been developed to quantify free cyanuric acid in the nylon extractant. Extraction efficiency of 88–133% and limit of detection of 0.4 ppm was obtained for free cyanuric acid in nylon polymer using this method. A liquid chromatography method with ultraviolet spectroscopic detection has been developed to quantify free melamine in the nylon extractant. Extraction efficiency of 76–90% and limit of detection of 2.8 ppm was realized for free melamine in nylon polymer using this method. These new analytical techniques have been successfully utilized to quantify free melamine and cyanuric acid in nylon 6/6,6 co‐polymer.
Application of naphthylcarbamate‐substituted β‐cyclodextrin bonded silica particles as stationary phase for high‐performance liquid chromatography
Authors: Gong Yinhan , Lee Hian Kee
Published: May 2003

Naphthylcarbamate‐substituted (3‐(2‐O‐β‐cyclodextrin)‐2‐hydroxypropoxy)‐propylsilyl‐appended silica gel (NSCD‐HPS) has been synthesized via a convenient liquid‐solid phase reaction on a silica gel surface. The chromatographic behavior of NSCD‐HPS in high‐performance liquid chromatography (HPLC) was studied with several disubstituted benzenes and some chiral aromatic compounds under both normal and reversed‐phase conditions. The results show that NSCD‐HPS has excellent selectivity for the separation of positional isomers of disubstituted benzenes and enantiomers of chiral aromatic compounds.
Development of packed capillary columns using carbon dioxide slurries
Authors: Planeta Josef , Karásek Pavel , Vejrosta Jiří
Published: May 2003

A modified procedure for the preparation of packed capillary columns by the use of supercritical or liquid carbon dioxide slurries is proposed. This technique removes the problems arising from sudden and rapid movement of sorbent suspension at the beginning of the filling process. The parameters influencing the packing process (temperature, pressure, and restrictor that controls the flow rate of CO2), have been optimized. The columns prepared under optimized conditions exhibit high efficiency (average value of the reduced plate height h′ ca. 2.2), and long term stability. An example of the SFC separation of polydimethylsiloxanes in silicone oil is presented.
Development of comprehensive two‐dimensional packed column supercritical fluid chromatography
Authors: Hirata Yukio , Hashiguchi Takashi , Kawata Etsushi
Published: May 2003

A comprehensive two‐dimensional supercritical fluid chromatographic system with conventional packed columns was developed. The system used a computer‐controlled ten‐port valve, a capillary trap, and a restrictor. The mobile phase was pure carbon dioxide. The first dimension column was operated under constant pressure in the stopped‐flow mode, while the second dimension column was operated in the constant flow mode. The effluent of the first column was depressurized through the restrictor and solute was trapped within the capillary trap. Then the trapped solute was transferred into the second column by switching the valve. Since the solute transfer process is very rapid, the valve can be switched back after a short injection period in order to collect next fraction. This allowed the sampling time to be changed without changing any of the other conditions, such as the second dimension run time. The system was applied to the separation of triglycerides in fats and oils. Separations were performed using the same ODS packing materials for both columns, and the first column was operated under subcritical conditions and the second column under supercritical conditions.
Enantiomeric separation of aminoglutethimide by capillary electrophoresis using native cyclodextrins in single and dual systems
Authors: Abushoffa Adel M. , Fillet Marianne , Marini Roland D. , Hubert Philippe , Crommen Jacques
Published: May 2003

Aminoglutethimide (AGT) is one of the few examples of chiral drugs that can be enantioseparated by capillary electrophoresis using any of the three native cyclodextrins: α‐, β‐, or γ‐CD. A complete resolution of the enantiomers of this compound in cationic form could be achieved with each of the three CDs, using a pH 3 phosphoric acid‐triethanolamine buffer. Affinity constants for AGT enantiomers with the three native CDs were determined, confirming that the highest selectivity was given by γ‐CD while the strongest complexation was obtained with β‐CD. However, an opposite affinity pattern was observed with the latter. Selectivity was lower for AGT enantiomers in dual CD systems, compared to that obtained with a single selector at its optimal concentration, which confirms that dual systems are of more limited interest when the two selectors have a similar effect on the analyte mobility. These results are in good agreement with those predicted using recently developed mathematical models.
Analysis of gastrodin and tetramethylpyrazine in traditional Chinese preparations by micellar electrokinetic chromatography
Authors: Rongying Wang , Wanyun Ma , Dieyan Chen
Published: May 2003

A simple, rapid, and accurate micellar electrokinetic chromatographic method has been developed for determination of gastrodin and tetramethylpyrazine in three traditional Chinese preparations: Zhennaoning jiaonang, Yangxue shengfa jiaonang, and Xiaoshuan zaizao wan. Running buffer comprising 50 mM sodium tetraborate and 15 M sodium dodecylsulfate (SDS), pH 9.50, was found to be most suitable for the separation. All experiments was performed with a 47 cm (40 cm effective length)×75 μm ID uncoated fused‐silica capillary and UV detection at 200 nm. The linear calibration ranges were 2.5–200 μg mL–1 (R = 0.999) for gastrodin and 5.0–200 μg mL–1 (R = 0.997) for tetramethylpyrazine; the detection limits were 0.5 μg mL–1 and 0.8 μg mL–1, respectively. Recoveries of the two analytes from the samples, calculated by use of a method described in detail in the text, were between 94.21 and 104.46%. The amounts of gastrodin and tetramethylpyrazine in the preparations were easily determined within 10 min.
Determination of dissociation constants of ten alkaloids by capillary zone electrophoresis
Authors: Gong Suxuan , Su Xiaodan , Bo Tao , Zhang Xu , Liu Huwei , Li Ke An
Published: May 2003

The dissociation constants of ten alkaloids, berbamine, (+)‐tetrandrine, thalifaretine, thalifaricine, northaltive, matrine, sophocarpine, sophoridine, oxymatrine, and oxysophocarpine isolated from herbal medicines Thalictrum and Sophora flavescens, were determined by capillary zone electrophoresis (CZE). The analysis time for each alkaloid was within 10 min under the following experimental conditions: acetate (pH 3.81–5.55) and phosphate buffer (pH 6.05–9.29) with ionic strength set at 0.03, applied voltage 30 kV, UV detection at 210 nm, capillary temperature 25°C. Effective mobility for each alkaloid and corresponding pH were fitted to an equilibrium expression by using nonlinear regression as well as linear regression, showing that the two models give comparable results for all studied alkaloids. The correlation coefficients were between 0.987 and 1.00 in the linear regression model, and between 0.978 and 1.00 in the nonlinear model. The measured pKa values for the ten alkaloids were from 5.7 to 7.8. The pKa values changed with the addition of organic additive to the buffer system.
Capillary electrochromatographic separation of ionizable compounds with a molecular imprinted monolithic cationic exchange column
Authors: Yan Weiying , Gao Ruyu , Zhang Zhichao , Wang Qinsun , Jiang Chun Vernon , Yan Chao
Published: May 2003

A polymer‐based monolithic capillary column imprinted with 4‐aminopyridine (4‐AP) was prepared by a thermally‐initiated polymerization process; and its performance as a capillary electrochromatographic medium was evaluated in separating 4‐AP and 2‐AP isomers. The effects of experimental parameters, such as pH value and ionic strength of the buffer, the acetonitrile content in the mobile phase, and the applied voltage, on the resolution of these isomers had been carefully investigated. It was found that in the retention process there were interplays of multiple mechanisms of ion‐exchange, molecular imprinting, and electrophoresis. These mechanisms allowed more sophisticated control of experimental parameters in the separation of ionizable compounds.
Decoding of complex isothermal chromatograms: Application to chromatograms recovered from space missions
Authors: Pietrogrande Maria Chiara , Tellini Ilaria , Felinger Attila , Dondi Francesco , Szopa Cyril , Sternberg Robert , Vidal‐Madjar Claire
Published: May 2003

In gas chromatographic isothermal separations of multicomponent mixtures, i.e., mixtures where the number of components is high and unknown, the efficiency is low and not enough to allow a complete separation with a consequent severe peak overlapping in the chromatogram. The consequence is a significant loss in analytical information content. Therefore it is practically mandatory to use a chemometric procedure to decode the complex chromatogram, i. e. to deconvolve the overlapping signal to extract from it information on the mixture and the separation system. Isothermal separations are not very popular, due to their low efficiency, but they are very common in in situ analyses during space missions, as a consequence of flight constraints on instrumentation complexity and power (energy saving). In this work a chemometric approach based on Fourier analysis is applied to chromatograms obtained under isothermal or low temperature programming conditions. These conditions simulate those employed in space missions. The procedure has been applied to standard mixtures containing compounds representative of the planetary atmospheres that will be investigated in the near future: in particular, those related to Titan's atmosphere (Cassini‐Huygens mission) and a cometary nucleus (Rosetta mission), i. e., hydrocarbons and oxygenated compounds with carbon atom numbers ranging from 2 to 8. The original approach, developed for constant peak width, is extended to variable peak width, in particular to the case of peak width linearly increasing with retention time, representing isothermal separations. The proposed approach is able to characterise complex isothermal chromatograms in terms of number of components present in the mixture and of separation efficiency: such results are useful in interpreting data recovered from space missions and for optimising analysis conditions compatible with flight constraints.
Peak amplitude and resolution in comprehensive gas chromatography using valve modulation
Authors: Hamilton Jacqueline F. , Lewis Alastair C. , Bartle Keith D.
Published: May 2003

Comprehensive two‐dimensional gas chromatography (GC×GC) allows major increases in peak capacity in comparison with separations on a single column. Interfacing the two columns in GC×GC has most often been achieved by thermal modulation. However, analyte transfer by valve modulation, in which fractions from the first column are introduced into the second column by means of a multi‐port valve, is also possible. In this paper we develop a previous model of peak amplitude enhancement to compare the sensitivity and resulting resolution possible in GC×GC with thermal and valve modulation. While the peak amplitude resulting from valve modulation is inevitably much less than in thermal modulation, there is still an enhancement in comparison to single column GC. Resolution (R) in GC×GC with the two modulation methods has also been compared and is predicted to be generally improved for the valve modulation of partially resolved (R = 1) narrow peaks from the first dimension column. A comparison of peak amplitude enhancement and retained resolution using thermal and valve modulation methods is made using the example of GC×GC analysis of gasoline vapour.