bluuebunny/crossref_metadata_2025 huggingface dataset:
Hepatic Targeting of Transplanted Liver Sinusoidal Endothelial Cells in Intact Mice *
Authors: Benten Daniel , Follenzi Antonia , Bhargava Kuldeep K. , Kumaran Vinay , Palestro Christopher J. , Gupta Sanjeev
Published: May 2005

Targeting of cells to specific tissues is critical for cell therapy. To study endothelial cell targeting, we isolated mouse liver sinusoidal endothelial cells (LSEC) and examined cell biodistributions in animals. To identify transplanted LSEC in tissues, we labeled cells metabolically with DiI-conjugated acetylated low density lipoprotein particles (DiI-Ac-LDL) or 111Indium-oxine, used LSEC from Rosa26 donors expressing β-galactosidase or Tie-2-GFP donors with green fluorescent protein (GFP) expression, and tranduced LSEC with a GFP-lentiviral vector. LSEC efficiently incorporated 111Indium and DiI-Ac-LDL and expressed GFP introduced by the lentiviral vector. Use of radiolabeled LSEC showed differences in cell biodistributions in relation to the cell transplantation route. After intraportal injection, LSEC were largely in the liver (60 ± 13%) and, after systemic intravenous injection, in lungs (67 ± 9%); however, after intrasplenic injection, only some LSEC remained in the spleen (29 ± 10%;

P

< .01), whereas most LSEC migrated to the liver or lungs. Transplanted LSEC were found in the liver, lungs, and spleen shortly after transplantation, whereas longer-term cell survival was observed only in the liver. Transplanted LSEC were distinct from Kupffer cells with expression of Tie-2 promoter-driven GFP and of CD31, without F4/80 reactivity. In further studies using radiolabeled LSEC, we established that the manipulation of receptor-mediated cell adhesion in liver sinusoids or the manipulation of blood flow–dependent cell exit from sinusoids improved intrahepatic retention of LSEC to 89 ± 7% and 89 ± 5%, respectively (

P

< .01).
In conclusion
, the targeting of LSEC to the liver and other organs is directed by vascular bed–specific mechanisms, including blood flow–related processes, and cell-specific factors. These findings may facilitate analysis of LSEC for cell and gene therapy applications. (Hepatology 2005.)
RF plasma treatment of metallic implant surfaces
Authors: Kummer Frederick J. , Ricci John L. , Blumenthal Norman C.
Published: May 2005

Radio‐frequency air plasma treatments of Ti‐6‐4 and Co‐Cr implants increased surface wettability but concurrently increased ionic release. In vitro tissue culture experiments demonstrated no enhancement of cell growth and enrichment. Short‐term rabbit tibial implants also showed no difference between treated and untreated implants.
Increase of stability in external fracture fixation by hydroxyapatite‐coated bone screws
Authors: Augat Peter , Claes Lutz , Hanselmann Karl‐Friedrich , Suger Gebhard , Fleischmann Wim
Published: May 2005

A major problem in fracture treatment by external fixation is screw loosening, which often results in reduced stability and can lead to prolonged treatment. A load‐carrying experiment was conducted to determine whether coating implants with bioactive hyroxyapatite (HA) increases screw stability. Twelve HA‐coated ASIF screws with 3 different macroporosities were inserted in 12 sheep that had already been fitted with a 6‐pin external fixator for the treatment of a tibial osteotomy. The same number of uncoated polished steel screws served as controls. Although initial stability was not different for HA‐coated screws, average removal torque after a 9‐week implantation period increased with increasing macroporosity of the HA coating (p <.002). Instability of some screws was accompanied by histologic findings of cartilagenous tissue and proliferation of periosteal callus. Near the threads in the tibial cortex and in the shaft area of the screw were seen large numbers of HA particles that had been sheared off during implantation as well as during screw removal because of high contract forces between the HA coating and bone. Particulate debris of HA particles as well as the release of small bone fragments during explantation is likely to be unavoidable since HA adherence to bone is greater than adherence to steel after several weeks of implantation. © 1995 John Wiley & Sons, Inc.
Osseous attachment to vitreous carbons
Authors: Stanitski Carl L. , Mooney Vert
Published: May 2005

Skeletal ingrowth to vitreous carbon was tested by means of bicortical corrugated vitreous carbon dowels of various groove sizes in dog femora and humeri. After a 4‐week ingrowth period, resistance of the implants to push out loads ranged from 66 to 100 kg. Comparable data was obtained from similar sized polymethylmethacrylate and vitreous carbon‐coated graphite implants. Histologic acceptability of the vitreous carbon appeared excellent in terms of minimal foreign body giant cell and fibrous tissue responses. Axial loading tests with femoral bone bridges demonstrated the vitreous carbon to be too brittle to withstand these functional loads. Experience with a canine skeletally fixed transcutaneous limb prosthetic device is presented.
Degradative analysis of glass ionomer polyelectrolyte cements
Authors: Cook Wayne D.
Published: May 2005

As part of a detailed investigation of the setting mechanisms of dental polyelectrolyte cements, the Al3+, Ca2+, and Na+ concentrations in the matrix phase of glass ionomer cements were measured as a function of the cements age by use of a selective degradation technique. In the early stages of cement formation, all three cations were rapidly released from the glass, and it is in‐ferred that both Ca2+ and Al3+ are responsible for gelation. Even after 5 × 104 min, the reaction was incomplete and still continuing.
Reduction of fibrinogen adsorption on PEG‐coated polystyrene surfaces
Authors: Bergström Karin , Holmberg Krister , Safranj Agneza , Hoffman Allan S. , Edgell Michael J. , Kozlowski Antoni , Hovanes Bruce A. , Harris J. Milton
Published: May 2005

Reduction of protein adsorption by coating surfaces with polyethylene glycol (PEG) is well documented. The present work has four goals related to these previous studies: first, to develop chemistry providing densely packed, covalently bound PEG on polystyrene (PS); second, to determine the ability of these modified surfaces to reject fibrinogen; third, to compare the protein‐rejecting ability of branched and linear PEGs; and fourth, to examine the utility of an ELISA‐type procedure for measuring protein adsorption. It was found that PEG‐epoxide could be readily coupled to amine groups of poly(ethy1ene imine) (PEI), which had been preadsorbed onto an oxidized PS surface. The PEG groups on branched PEGs appear to act as an excluded volume to repel proteins, similar to arguments previously raised for linear PEGs. The results of protein adsorption studies showed that fibrinogen adsorption is significantly reduced by coating polystyrene with either linear or branched PEGs of 1500 to 20,000 in molecular weight. The ELISA technique was found to be equivalent in sensitivity to radiolabeled fibrinogen for estimating adsorption levels. It is expected that PEG‐coated PS will have much utility in a variety of biomedical applications.
The fracture toughness of titanium‐fiber‐reinforced bone cement
Authors: Topoleski L. D. Timmie , Ducheyne Paul , Cuckler John M.
Published: May 2005

Fracture of the poly(methyl methacrylate) bone cement mantle can lead to the loosening and ultimate failure of cemented total joint prostheses. The addition of fibers to the bone cement increases fracture resistance and may reduce, if not eliminate, in vivo fracturing. This study discusses the effect of incorporating titanium (Ti) fibers on fracture toughness. Essential characteristics of the composite bone cement included a homogeneous and uniform fiber distribution, and a minimal increase in apparent viscosity of the polymerizing cement. Ti fiber contents of 1%, 2%, and 5% by volume increased the fracture toughness over non‐reinforced bone cement by up to 56%. Bone cements of two different viscosities were used as matrix material, but when reinforced with the same fiber type and content, they showed no difference in fracture toughness. Four different fiber aspect ratios (68, 125, 227, 417) were tested. At 5% fiber content, there was no statistically significant dependence of fracture toughness on fiber aspect ratio. Scanning electron microscopy revealed important toughening mechanisms such as fiber/matrix debonding, local fracture path alteration, and ductile fiber deformation and fracture. Fiber fracture was evidence that the critical fiber length was exceeded. The surfaces of the Ti fibers were rough and irregular, indicating that a high degree of mechanical interlock between matrix and fiber was likely. The energy absorption contribution of plastic deformation and ductile fracture is absent in brittle fibers, like carbon, but is a distinction of the Ti fibers used in this study. © 1992 John Wiley & Sons, Inc.
The effects of bone cement powder on human adherent monocytes/macrophages in vitro
Authors: Davis R. G. , Goodman S. B. , Smith R. L. , Lerman J. A. , Williams R. J.
Published: May 2005

This study reports the effects of Simplex bone cement powder (BC) on the proliferation and production of bone resorbing factors in vitro by human adherent monocytes/macrophages. Adherent peripheral blood cells were isolated from seven healthy individuals and exposed to a dispersion of BC powder (1 mg/mL), phytohemagglutinin (PHA, 40 μg/mL), or medium alone at different periods of cell incubation (days 0–2, 0–7, 5–7, or 10–12). Cell proliferation was quantified by incorporation of 3H‐thymidine uptake. Culture supernatants were evaluated for levels of interleukin 1‐like activity (IL‐1) by murine thymocyte proliferation assay, prostaglandin E2 (PGE2) by radioimmunoassay, lysosomal enzyme activity (N‐acetyl‐β‐D‐glucosaminidase and β‐glucuronidase) using fluorometry, and collagen and casein degrading activity using radioactive substrates. Human adherent peripheral blood cells showed a proliferative response to PHA that coincided with cell maturation; BC did not inhibit PHA‐induced cell proliferation of either adherent or nonadherent blood cells, indicating the non‐toxic nature of these particles at the concentrations tested. BC stimulated increased release of the lysosomal enzyme N‐acetyl‐β‐D‐glucosaminidase; the levels of PGE2, IL‐1, collagenase, and caseinase were unchanged. © 1993 John Wiley & Sons, Inc.
Lens‐on‐surface method for investigating adhesion of Staphylococcus aureus to solid surfaces incubated in blood plasma
Authors: Elwing Hans , Askendal Agneta
Published: May 2005

Adhesion of Staphylococcus aureus was investigated on flat silicon oxide surfaces that had been incubated in human plasma at different concentrations. Adhesion of bacteria did not occur at high incubation concentrations of plasma or when the surface had been incubated in egg albumin. However, significant adhesion was observed when plasma was diluted. With the use of an antibody method, it was noted that the adhesion of the bacteria coincided with adsorbed fibrinogen, and possibly also with IgG. We also investigated the effect of “narrow space” on the adsorption of blood plasma and subsequent adhesion of S. aureus. In these experiments, blood plasma was incubated under a convex lens placed upside‐down on the silicon oxide surface. This method creates a continuous gradient of space from the contact point of the lens and outward. After rinsing off the plasma and the lens, the surface was incubated with a suspension of S. aureus followed by quantification of the attached bacteria by means of optical methods. Adhesion of bacteria occurred in several circular zones that were easily detectable with the naked eye or by the means of simple optical methods. In addition, in these experiments, adhesion coincided with adsorbed fibrinogen or IgG at the surfaces. The increased bacterial adhesion to surfaces incubated in diluted plasma, or plasma incubated in narrow space, is a variant of the so‐called “Vroman effect.” With a model protein system consisting of fibrinogen and IgG and the corresponding antibodies, we demonstrate that “dilution” and “incubation in narrow space” are two phenomenologically similar methods. This methodologic investigation demonstrated that the lens‐on‐surface method is superior for the investigation of these aspects of bacterial adhesion. © 1994 John Wiley & Sons, Inc.
Osseous regeneration in the rat calvarium using novel delivery systems for recombinant human bone morphogenetic protein‐2 (rhBMP‐)
Authors: Kenley R. , Marden L. , Turek T. , Jin L. , Ron E. , Hollinger J. O.
Published: May 2005

In the current investigation, we report osseous regeneration in critical‐size rat calvarial defects using recombinant human bone morphogenetic protein‐2(rhBMP‐) and novel delivery systems based on biomaterials. The novel systems combine rhBMP‐ with dry powder microparticles of poly(D, L‐lactide‐co‐glycolide) (PLGA). The mixture of rhBMP‐ with PLGA microparticles is added to an aqueous solution of biopolymer to yield a semisolid paste. The biopolymers tested include autologous blood clot, hydroxypropyl methylcellulose, and sodium alginate cross‐linked with calcium ion. Insoluble collageneous bone matrix was also studied as a control. Test articles were made at 0‐, 10‐, and 30‐µg doses of rhBMP‐ and implanted in 8‐mm‐diameter rat calvarial defects (which will not heal if left untreated). The animals were examined 21 days after implantation by radiography, radiomorphometry, histology, and histomorphometry. All tested materials containing rhBMP‐ restored radiopacity and normal contouring to the calvarial defects. Samples without added rhBMP‐ yielded only soft tissue within the defects. Histology showed restoration of inner and outer bone tables plus marrow constituents. The PLGA microparticles were significantly resorbed at the 21‐day time point. Although small differences between delivery systems were evident at 0‐ and 10‐µg rhBMP‐ doses, all test articles performed essentially equivalently at the 30‐µg dose. Thus, novel delivery systems for rhBMP‐ offer the promise of combining the intrinsic bioactivity of the osteoinductive protein with pharmaceutically acceptable biomaterials. © 1994 John Wiley & Sons, Inc.
Osteoblast function on synthetic biodegradable polymers
Authors: Ishaug Susan L. , Yaszemski Michael J. , Bizios Rena , Mikos Antonios G.
Published: May 2005

Rat osteoblasts were cultured on films of biodegradable poly(L‐lactic acid) (PLLA), 75:25 poly(DL‐lactic‐co‐glycolic acid) (PLGA), 50:50 PLGA, and poly(glycolic acid) (PGA) for up to 14 days. Osteoblasts attached equally well to all the polymer substrates after 8 h in culture. By day 4 in culture, osteoblasts had exceeded confluency numbers, and their proliferation leveled off by day 7. An increase in alkaline phosphatase (ALP) activity from 1.92 (±0.47) × 10−7 for day 7 to 5.75 (±0.12) × 10−7 μmol/cell per min for day 14 was reported for osteoblasts cultured on 75:25 PLGA, which was comparable to that observed for tissue culture polystyrene (TCPS) controls. The ALP activities expressed by osteoblasts cultured on PLLA, 50:50 PLGA, and PGA films did not significantly increase over time. Collagen synthesis for osteoblasts cultured on all polymer substrates was similar to that of TCPS and did not vary with time. The morphology of cultured osteoblasts was not affected by the continuous degradation of the polymer substrates. These results demonstrate that poly(α‐hydroxy esters) can provide a suitable substrate for osteoblast culture and hold promise in bone regeneration by osteoblast transplantation. © 1994 John Wiley & Sons, Inc.
Isolation of predominantly submicron‐sized UHMWPE wear particles from periprosthetic tissues
Authors: Campbell P. , Ma S. , Yeom B. , McKellop H. , Schmalzried T. P. , Amstutz H. C.
Published: May 2005

A method of tissue digestion using sodium hydroxide was applied to the isolation and recovery of ultra‐high‐molecular‐weight polyethylene (UHMWPE) particles from tissues around failed total hip replacements. Density gradient ultracentrifugation of the digested tissues was performed to separate the UHMWPE from cell debris and other particulates. Fourier transform infrared spectroscopy and differential scanning calorimetry (DSC) verified that the recovered particles were UHMWPE. When viewed by scaning electron microscopy, individual particles were clearly observed and were either rounded or elongated. The majority were submicron in size. The application of this method to the study or particles from periprosthetic tissues may elucidate aspects of biomaterial particles size and shape that are important to the biologic response to, and clinical outcome of, total joint replacement. © 1995 John wiley & Sons, Inc.
Influence of implant location on the mechanical characteristics using the transcortical model
Authors: Dalton Jeanette E. , Cook Stephen D.
Published: May 2005

Mechanical evaluation of implants harvested following surgical implantation is often performed as part of the screening process for new materials or surface textures. The question of randomization with respect to implant placement often arises when attempting to design a study to evaluate several implant types, while minimizing the number of animals required to perform the investigation. The purpose of this study was to analyze the effects of implant placement within the canine femur on mechanical characteristics of the bone–implant interface when using the transcortical model. Both smooth and porous‐surfaced implants were evaluated at several time periods to determine the effects of placement in the medial versus left cortex, proximal versus distal placement, and left versus right femur. The smooth‐surfaced implants demonstrated no significant effects due to placement within the femur. The results demonstrate the necessity for careful study design when evaluating smooth surfaced implants; however, paired comparisons in either the medial versus lateral cortex or left versus right femur will provide unbiased comparisons between the implants. © 1995 John Wiley & Sons, Inc.
Interface mechanics and histomorphometric analysis of hydroxyapatite‐coated and porous glass‐ceramic implants in canine bone
Authors: Nimb Lars , Jensen Jørgen Steen , Gotfredsen Klaus
Published: May 2005

A canine study was performed to make a histological and biomechanical evaluation of the interface between bone and two different bioceramic implants. A newly developed glass‐ceramic formed by P2O5, CaO, SiO2, and Al2O3, giving a crystal phase composed of CaP2O6AlPO4SiP2O7, was compared to hydroxyapatite (HA) coated Ti6Al4V implants. A total of 24 implants were inserted into the femoral condyle of 15 adult female golden retriever dogs weighing 20–25 kg. There was a 12 week follow‐up. Implants were examined by mechanical testing, histology, histomorphometry, microradiograpic methods, and EDAX analysis. The ultimate shear strength for the HA‐coated implants was significantly higher than in the glass‐ceramic group. When these values were related to the histomorphometric measurements, the difference could be explained by the tissue‐to‐implant contact. The glass‐ceramic showed direct contact only with nonmineralized, osteoid bone. The HA‐coated implants, however, were integrated into the bone. The study indicated that porous glass‐ceramic containing AlPO4 causes local osteomalacia and might not be suitable for clinical purposes. © 1995 John Wiley & Sons, Inc.
Introduction: Protein phosphorylation and signal transduction in bacteria
Authors: Saier Milton H.
Published: May 2005

A single type of reversible protein‐phosphorylating system, the ATP‐dependent protein kinase/phosphatase system, is employed in signal transduction in eukaryotes. By contrast, recent work has revealed that three types of protein‐phosphorylating systems mediate signal transduction in bacteria. These systems are (1) classical protein kinase/phosphatase systems, (2) sensor‐kinase/response‐regulator systems, and (3) the multifaceted phosphoenolpyruvate‐dependent phosphotransferase system. Physiological, structural, and mechanistic aspects of these three evolutionarily distinct systems are discussed in the papers of this written symposium. © 1993 Wiley‐Liss, Inc.
Regulatory interactions involving the proteins of the phosphotransferase system in enteric bacteria
Authors: Saier Milton H.
Published: May 2005

Sugar uptake and cytoplasmic inducer generation as well as cyclic AMP synthesis are regulated by the phosphoenolpyruvate:sugar phosphotransferase system (PTS) in Gram‐negative enteric bacteria. In these organisms, the free form of the glucose‐specific Enzyme IIA (IIAglc) of the PTS, which can be phosphorylated on a histidyl residue by PEP and the PTS energy coupling proteins, inhibits the activities of non‐PTS carbohydrate permeases and catabolic enzymes. By contrast, the phosphorylated form of IIAglc appears to activate adenylate cyclase, the cyclic AMP biosynthetic enzyme. What is known of the molecular details of these regulatory interactions will be summarized, and a novel regulatory mechanism involving the fructose repressor, FruR, which controls the transcription of genes encoding enzymes which catalyze reactions in central pathways of carbon metabolism, will be presented. © 1993 Wiley‐Liss, Inc.
Analysis of the mitogenic effect of fetuin preparations on arterial smooth muscle cells: The role of contaminant platelet‐derived growth factor
Authors: Libby Peter , Raines Elaine W. , Cullinane Paula M. , Ross Russell
Published: May 2005

Fetuin, a major protein of fetal calf serum, partially purified by the method of Pedersen, stimulated growth of aortic smooth muscle cells. More highly purified fetuin preparations stimulated growth less than Pedersen fetuin, as previously described for other cell types, suggesting that this activity is due to a contaminant. Recently bovine alpha2‐macroglobulin or “Embryonin” has been proposed as the mitogenic component of crude fetuin preparations. We found that active fetuin preparations did contain alpha2‐macroglobulin that stimulated smooth muscle cell growth. However, alpha2‐macroglobulin purified directly from platelet‐poor bovine plasma or fetuin purified from Pedersen fetuin by gel filtration lacked appreciable mitogenic effect on smooth muscle cells. Since alpha2‐macroglobulin can bind platelet‐derived growth factor (PDGF), and since highly acidic fetuin might bind the very basic PDGF molecule non‐specifically, we measured the PDGF content of various fetuin preparations and found a good correlation between the PDGF content and mitogenic activity. Gel filtration experiments demonstrated that in Pedersen fetuin PDGF occurred both free, and in association with alpha2‐macroglobulin. We conclude that the principal mitogenic component for smooth muscle cells in crude fetuin preparations is PDGF, since purified bovine alpha2‐macroglobulin or fetuin do not appreciably affect growth of these cells. These results help to resolve a long‐standing controversy regarding the nutrition of cultured cells. In addition, we suggest that before alpha2‐macroglobulin or “Embryonin” is accepted as a bona fide growth factor for a given cell type, the role of contamination with PDGF should be assessed.
A stochastic model for mast cell proliferation in culture
Authors: Pharr Pamela N. , Nedelman Jerry , Downs Heather P. , Ogawa Makio , Gross Alan J.
Published: May 2005

A birth‐death model was developed for the proliferation of mast cells. According to the model, each secondary mast cell colony starts with one proliferative cell. At each generation each cell chooses among three possibilities: (1) division into two proliferative cells; (2) division into two non‐proliferative cells; or (3) disappearance. At each step, a non‐proliferative cell either does nothing or disappears. A computer simulation of this model could be fitted reasonably well to our data for the size distributions of secondary mast cell colonies recorded after different culture periods. Our model predicts that proliferative cells comprise a larger fraction of the colony in large secondary colonies than in small ones. This prediction was successfully tested by examination of tertiary colony formation. This is a general model for cell proliferation that may be applicable to other types of cells.
Differential effects of the tumor promoter phorbol‐12‐myristate‐13‐acetate on the morphological and biochemical differentiation of N‐18 mouse neuroblastoma cells
Authors: Liu Alice Y.‐C. , Chen Kuang Yu
Published: May 2005

The phorbol ester tumor promoter phorbol‐12‐myristate‐13‐acetate (PMA) was found to have differential inhibitory effects on the expression of morphological and biochemical differentiation of N‐18 mouse neuroblastoma cells. PMA completely inhibited neurite extension and associated growth characteristics and partially inhibited the increased expression of R1 cAMP‐binding protein; PMA had no effect on the induction of acetylcholinesterase activity in cells prompted to differentiate either by treatment with 1 mM dibutyryl cAMP or by serum deprivation. 4‐α‐Phorbol‐12, 13‐didecanoate, an inactive analogue of phorbol ester tumor promoter, was without effect. The implications of these findings concerning the mechanism of action of phorbol ester tumor promoters in the control of cell differentiation are discussed.
Alterations in superoxide dismutase, glutathione, and peroxides in the plasmodial slime mold Physarum polycephalum during differentiation
Authors: Allen R. G. , Newton R. K. , Sohal R. S. , Shipley G. L. , Nations C.
Published: May 2005

Changes in the level of antioxidant defenses and the concentration of free radical by‐products were examined in differentiating (M3cVII and LU897 × LU863), non‐differentiating (LU887 × LU897), and heterokaryon microplasmodia of the slime mold Physarum polycephalum during spherulation in salts‐only medium. As differentiation proceeded, superoxide dismutase activity increased by as much as 46 fold; glutathione concentration and the rate of oxygen consumption decreased; cyanide‐resistant respiration, hydrogen peroxide, and organic peroxide concentrations increased. The non‐differentiating culture failed to exhibit any of these changes. A heterokaryon obtained by the fusion of differentiating and non‐differentiating strains was observed to differentiate at a very retarded rate and to exhibit the changes observed in the spherulating strains at a correspondingly slower rate. These observations suggest that a free radical mechanism may be involved in the differentiation of Physarum microplasmodia into spherules.
Modulation of fibroblast‐induced clot retraction by calcium channel blocking drugs and the monoclonal antibody ALB6
Authors: Azzarone Bruno , Krief Patricia , Soria Jeannette , Boucheix Claude
Published: May 2005

Suspensions of living human fibroblast induce fibrin clot retractile activity (FCR). The efficiency is dependent on the growth phase; it is maximal during active growth and reduced in post‐confluent cultures. In contrast human osteosarcoma cells constantly exhibit very low FCR efficiency. Two different calcium channel‐blocking drugs Diltiazem and Verapamil inhibit, depending on the concentrations employed, FCR, and spreading within the clots of the normal cells. Intermediate FCR levels are associated with intermediate degrees of spreading. A similar dose dependent inhibition is also obtained by treating the normal cells with the calmodulin inhibitor trifluoperazine (TFP). On the other hand, treatment of the normal cells with the monoclonal antibody ALB6 which is directed at the human leukocyte differentiation antigen CD9 (p24) causes a significant increase in the FCR efficiency in post‐confluent normal cells, but it has no effect on the Te85 osteosarcoma cells. Moreover ALB6 IgG reverses the FCR inhibitory effect of the calcium‐channel blocking drugs but not that of TFP. This means that the ALB6 IgG target on the cellular membrane is probably the same as that of the two drugs and that ALB6 IgG is active in the regulation of the calcium flux which controls fibrin clot retractile activity of normal human fibroblasts.
A colony‐stimulating factor for neutrophil granulocytes: A marked increase of its production by the addition of sodium butyrate and lipopolysaccharide in serum‐free culture of RSP‐2 · P3 Cells
Authors: Tsuneoka K. , Shikita M.
Published: May 2005

Sodium butyrate, lithium acetate, and hydroxyurea given to serum‐free culture of RSP‐2 · P3 cells notably reduced the rate of cell proliferation but markedly enhanced the production of such a colony‐stimulating factor (CSF) as one that stimulated predominantly neutrophilic granulocyte colony formation in mouse bone marrow cell cultures (Tsuneoka and Shikita, 1984). On the other hand, the production of macrophage CSF was not increased in the butyrate‐treated RSP‐2 · 3 cells. Butyrate also failed to enhance either macrophage CSF or neutrophil CSF production in L · P3 (mouse fibroblast line), Huk‐1 · P3 (human kidney cell line) or Nil2C2 (hamster embryo fibroblast line) cells. The addition of bacterial lipopolysaccharide (LPS) together with butyrate resulted in further pronounced enhancement of the neutrophil CSF production in RSP‐2 · P3 cells, while the cells did not develop tolerance against LPS upon repeated challenge. The yield of neutrophil CSF was thus increased by about 45 times that of the control during continuous culture for 12 days. Large‐scale culture of the cells under these conditions must be an excellent source of a CSF for neutrophil granulocytes.
Flow cytometric analysis of tetanus toxin binding to neuroblastoma cells
Authors: Notter Mary F. D. , Leary James F.
Published: May 2005

A neuroblastoma cell line was assessed for its capacity to bind tetanus toxin (TT) by using immunofluorescence and flow cytometry to analyze cells on a single cell basis. A clone of Neuro 2a, N2AB‐1, was shown to bind variable amounts of TT per cell and this binding could be saturated by increasing doses of the toxin. Toxin binding was specific for neuronal cells, as the non‐neuronal cell line, C6 glioma, bound negligible amounts of toxin. Variability of immunofluorescence staining was due in part to the increase in size of N2AB‐1 cells as they progress through the cell cycle as measured by cell surface densities of toxin binding and DNA levels by propidium iodide (Pl) staining. When N2AB‐1 cells were treated with exogenous gangliosides for 24 h, cells were induced to sprout neurites and cell growth was inhibited. Analysis of DNA histograms indicated that ganglioside treatment caused more cells to appear in G0G1 of the cell cycle than that seen for untreated controls. Upon cytometric analysis of TT binding to ganglioside treated cells, it was apparent that treatment stimulated all cells to bind TT in larger amounts per cell than that seen with untreated N2AB‐1 cells. These data suggest that TT binding and, therefore, toxin receptors are constant in density throughout the cell cycle of these neuroblastoma cells and that exogenous gangliosides can cause differentiation followed by increased toxin binding.
Growth kinetics as a function of ploidy in diploid, tetraploid, and octaploid smooth muscle cells derived from the normal rat aorta
Authors: Rosen Eliot M. , Goldberg Itzhak D. , Shapiro Howard M. , Zoller Lawrence C. , Myrick Kyl V. , Levenson Stephen E. , Halpin Patricia A.
Published: May 2005

The smooth muscle cell population in major arteries of humans and experimental animals is heterogeneous with regard tocellular DNA content. A proportion of cells has polyploid DNA content and this proportion increases with normal aging and with hypertension. We have isolated pure populations of rat aortic smooth muscle cells containing 2C, 4C, and 8C DNA content by cloning of cultures of cells previously subjected to flow cytometric cell sorting. Karyologic analysis of these clonal populations revealed them to be pure diploid, tetraploid, and octaploid populations, respectively, containing 2N (= 42), 4N, and 8N chromosomes. Cell attachment area and nuclear size appeared to increase with the level of ploidy. Studies of the proliferative characteristics of the cells revealed that the growth rate and ultimate cell densities achieved decreased as the ploidy level increased. The intrinsic cellular radiosensitivity of these clones did not vary with ploidy. Increased smooth muscle cell ploidy is, therefore, associated with a decreased rate of proliferation. The emergence of smooth muscle cells with polyploid DNA content under normal and pathologic conditios is probably due to mitotic polyploidization without net cell proliferation and may be related to the need for expression of differentiated functions.
Commitment to differentiation of human promyelocytic leukemia cells (HL60): An all‐or‐none event preceded by reversible losses of self‐renewal potential
Authors: von Melchner Harald , Höffken Klaus
Published: May 2005

A method for clonal analysis has been developed which allows the characterization of the number and type of progeny cells produced by each single cell arising during clonal evolution. The method is based on a symmetry of self‐renewal exhibited by sister cells of the human promyelocytic leukemia cell line ‐HL60‐. This permits the use of one of the sister cells to measure the potential for self renewal of the other.

Using a system of sequential daughter cell transfers in semisolid medium, we have analysed self‐renewal and differentiation in individual clones exposed to all‐trans retinoic acid or dimethylsulfoxide (DMSO). We find that in clones exposed to chemical inducers of differentiation commitment occurs as an all‐or‐none event which is preceded by coordinated but reversible losses of self‐renewal potential.

It is concluded that the differentiation pathway of HL60 cells has two distinct portions. These are, first, a predeterministic portion, reflected by coordinated but reversible losses of self‐renewal potential, and second, a deterministic portion, reflected by irreversible phenotypic differentiation.
Glycosaminoglycan production in cultures of early and late passage human endothelial cells: The influence of an anionic endothelial cell growth factor and the extracellular matrix
Authors: Gordon Portia B. , Conn Greg , Hatcher Victor B.
Published: May 2005

An endothelial cell (EC) growth factor isolated from bovine brain stimulates in vitro growth of human umbilical vein endothelial cells, and permits long term serial propagation. In the presence of increasing concentrations of EC growth factor, confluent cultures of early (CPDL ⩽ 20) and late (CPDL > 20) passage human endothelial cells exhibit an increased incorporation of 3H‐glucosamine and Na235SO4 into the glycosaminoglycans (GAG), hyaluronic acid, chondroitin, chondroitin‐4‐sulfate, dermatan‐4‐sulfate, and chondroitin‐6‐sulfate. An increase in both labelled sulfated and nonsulfated GAG was observed in the cytosol, membrane, secreted and extracellular matrix fractions. In contrast, endothelial cells grown in the presence of EC growth factor contained decreased amounts of labelled heparan sulfate than cells grown without EC growth factor. Confluent cultures of early passage cells had significantly more labelled GAG but significantly less heparan sulfate than cultures of late passage cells on a per cell basis. Extracellular matrix from early passage cells contained about two‐ to seven‐fold more labelled GAG than extracellular matrix from late passage cells, but only about half as much labelled heparan sulfate. Cell adhesion was enhanced when cells were grown in the presence of EC growth factor as compared to adhesion of cells grown without EC growth factor. Conversely, trypsin‐mediated detachment of cells grown in the presence of growth factor was inhibited as compared to detachment of cells grown in medium without EC growth factor. The composition of the extracellular matrix influenced incorporation of labelled GAG into extracellular matrix. Early passage cells grown to confluence on a matrix from late passage cells incorporated significantly less labelled GAG into extracellular matrix than when grown to confluence on matrix from early passage cells. Incorporation of labelled GAG into extracellular matrix was significantly higher when late passage cells were grown on matrix from late passage cells. We conclude that (1) EC growth factor selectively stimulates incorporation of isotopic precursors into GAG in cultures of early and late passage endothelial cells but inhibits incorporation of radiolabel into heparan sulfate; (2) early passage cells contain more GAG but less heparan sulfate than late passage cells; (3) extracellular matrix controls the amount of GAG and heparan sulfate incorporated into matrix; (4) cells grown in the presence of EC growth factor are more adhesive to the substratum and more resistant to detachment by proteolytic enzymes than cells grown in medium without EC growth factor.
Transferrin receptor regulation is coupled to intracellular ferritin in proliferating and differentiating HL60 leukemia cells
Authors: Rhyner Kaspar , Taetle Raymond , Bering Harriet , To Dong
Published: May 2005

Cultured myeloid leukemia cells display transferrin receptors but decrease receptor display after differentiation induction or accumulation of intracellular iron. To determine whether regulation of transferrin receptors and ferritin were linked under these disparate conditions, serum‐free and fetal bovine serum (FBS) cultures of HL60 promyelocytic leukemia cells were used to investigate relationships between transferrin receptor display and intracellular ferritin. Using 125I‐ transferrin binding and immunofluorescence staining for transferrin receptors, HL60 cells cultured in serum‐free, transferrin‐free medium expressed fewer transferrin receptors and contained increased ferritin when compared to cells cultured with FBS or transferrin supplemented, serum‐free medium. When placed in medium containing transferrin, cells previously grown in transferrin‐free medium rapidly re‐expressed transferrin receptors and decreased their ferritin content. HL60 cells induced to differentiate into granuiocytes or macrophages also decreased transferrin receptor display and increased their ferritin content. Transferrin receptor display and ferritin content in both proliferating and differentiating myeloid leukemia cells are inversely related and their regulation is closely linked. Regulation of transferrin receptor display and ferritin synthesis may be important events regulating myeloid cell growth and differentiation.
The edge‐transitive but not vertex‐transitive cubic graph on 112 vertices
Authors: Conder Marston , Malnič Aleksander , Marušič Dragan , Pisanski Tomaž , Potočnik Primož
Published: May 2005

A detailed description is given of a recently discovered edge‐transitive but not vertex‐transitive trivalent graph on 112 vertices, which turns out to be the third smallest example of such a semisymmetric cubic graph. This graph has been called the Ljubljana graph by the first author, although it is believed that its existence may have been known by R. M. Foster. With the help of some advanced theory of covering graphs, various properties of this graph are analyzed, including a connection with the Heawood graph via ideals over polynomial rings. © 2005 Wiley Periodicals, Inc.
Synchronized temperature/density programming in capillary supercritical fluid chromatography
Authors: Later D. W. , Campbell E. R. , Richter B. E.
Published: May 2005

The theoretical and practical implications of simultaneous temperature/pressure and synchronized density/temperature programming are considered. Examples are shown for separations of dimethylpolysiloxanes where these techniques provide superior separation over their analogous isothermal programming methods.
Static coating of phenyl and biphenyl polysiloxane stationary phases on small‐diameter capillary columns
Authors: Woolley C. L. , Tarbet B. J. , Markides K. E. , Bradshaw J. S. , Lee M. L. , Bartle K. D.
Published: May 2005

Static coating of phenyl and biphenyl polysiloxane stationary phases on 50 μm i.d. open tubular capillaries was studied. The influence of coating solvents and coating temperatures on the viscosities and surface tensions of the polymer stationary phases and their coating solutions was determined. A measure of the Rayleigh instability paralled the observed coating efficiencies.
“Groove‐injection” as a novel method for sub‐microliter (nanoliter) injections in liquid chromatography using a conventional multi‐port valve
Authors: Berry V. , Lawson K.
Published: May 2005

In liquid chromatography with “low‐dispersion methods”, there is an increasing need to reproducibly inject nanoliter sample volumes. Low‐dispersion methods produce very narrow peaks because of short column length, narrow column bore, small particle packing, low particle surface area, open tubular configuration, or combinations of these parameters.

This paper describes a new injector method, the “groove‐injector” which involves simple plumbing changes for use of a conventional multi‐port valve (8‐ports or more) to inject sample volumes approximating a single groove in such a valve (e.g 30 nanoliters with aceptable reproducibility, ca. 8% RSD). In addition, by changing a resistor, volumes between 30, and over 2,000 nanoliters (nearly two orders of magnitude) can be injected with reproducibilities generally below 2% RSD. Different samples can be injected by using an autosampler.

Compared to commonly used 4‐port valves for nanoliter injections, multi‐port valves have a number of advantages. Multiport valves generally are more commonly available and they are a better financial investment because of their versatility for column switching, sample enrichment, or variable volume injections. Previously, submicroliter (nanoliter) injections have not been possible with multi‐port valves in as direct and simple a manner as described here.
Computer‐assisted chromatogram evaluation in dual capillary gas chromatography
Authors: Neu H. J. , Larsen M. , Panzel H. , Merz W.
Published: May 2005

Gas‐chromatographic analysis of complex mixtures is simplified enormously by the use of the simultaneous dual capillary technique. The advantages over a single‐column system are that the components are more reliably identified and quantified. After integration has taken place, the data from both capillaries are cor‐related with the aid of a computer program whose principles are described.
Solvent modulation: An accurately modeled method for controlling solute retention in liquid chromatography
Authors: Wahl J. H. , Enke C. G. , McGuffin V. L.
Published: May 2005

An innovative solvent delivery method termed solvent modulation has been developed to control solute retention in liquid chromatography. Solvent modulation is the technique whereby individual solvent zones are introduced onto the chromatographic column in a known random orrepeating sequence. Because the solvent zones are of constant composition and are spatially separated from one another, solute retention is controlled independently in each zone. Hence, the overall retention of a solute is a time‐weighted average of the capacity factors in the solvent zones it has encountered. Solvent modulation offers a simple, versatile, and accurately modeled means to control and predict solute retention in liquid chromatography.
High sensitivity laser induced fluorescence detection in capillary zone electrophoresis
Authors: Nickerson B. , Jorgenson J. W.
Published: May 2005

Laser induced fluorescence is used for the detection of labeled amino acids. A preliminary comparison is made of three fluorescence pre‐column labeling reagents, ortho‐phthaldialdehyde, naphthalene dicarboxaldehyde, and fluorescein isothiocyanate, and data on phenylalanine detection limits are given.
Selectivity enhancement of a metal‐sensitive flame ionization detector for capillary gas chromatography
Authors: Gallagher M. M. , Hill Herbert H.
Published: May 2005

A novel modification of a hydrogen‐atmosphere flamo ionization detector (HAFID) is presented which attenuates response to hydrocarbon compounds, significantly enhancing selectivity towards organometallic compounds by more than an order of magnitude. Chromatograms of an organometallic compound test mixture and regular leaded gasoline are presented to depict the specificity of the response.
The development of amphids and amphidial glands in adult Syngamus trachea (Nematoda: Syngamidae)
Authors: Jones Gwyneth M.
Published: May 2005

Nematode amphids are a pair of lateral cephalic sense organs, each comprising a group of sensory endings terminating in a cuticle‐lined pit. In Syngamus trachea, a parasite of birds, each amphid is surrounded by two non‐nervous supporting elements, a large gland cell basally and a smaller supporting cell anteriorly. The amphidial glands display high levels of secretory activity from five to six days postinfection. Secretory material is discharged through the lumen of the sense organ onto host tissue. The ultrastructure of amphids and amphidial glands has been investigated in newly moulted, immature and mature adults to trace the development of glandular activity and its effect on amphid‐amphidial gland relationships. In newly moulted adults, the glands have very low levels of secretory activity and appear to act only as supporting cells to the amphids. As secretory activity increases, the gland cell membrane surrounding the sensory endings is elaborated into a reticulum which probably forms the secretory surface. In mature adults the amphid pit is swollen and filled with secretion; the sensory endings are relegated to the periphery of the lumen. It is suggested that amphidial glands develop from typical supporting cells, but acquire a new role possibly associated with parasite attachment.
Origin and fate of germ cells in male and female embryos of Haplothrips verbasci (Osborn) (Insecta, Thysanoptera, Phlaeothripidae)
Authors: Heming B. S.
Published: May 2005

Comparison of germ cells in male and female embryos of the arrhenotokous thrips, Haplothrips verbasci, yields the following observations: A mean of 11 cleavage energids enter the posterior pole plasm of the egg after the sixth cleavage division and apparently become pole cells when they take up polar granules in their cytoplasm. The cells proliferate asynchronously prior to and during anatrepsis to yield a mean of 36 germ cells in male embryos and 31 in females. Visible sexual differentiation of germ cells begins during germ band elongation and is completed shortly after the appearance of appendages. Female germ cells are larger than those of the males and may contain two nucleoli. The germ cells separate into two groups just before katatrepsis and mesodermal cells collect about these to form the primary epithelial sheaths of the gonads and the primordia of the gonoducts shortly after revolution is completed. Each gonad contains a mean of 13 germ cells in male embryos and 7 in females – a number that persists until mitosis resumes after hatching. During ketatrepsis, a mean of 11 germ cells in male embryos and 2.6 in females fail to be enclosed within the gonads, become dispersed in the yolk and perhaps transform into vitellophages.

Germ cell development in H. verbasci embryos resembles similar events taking place in psocid embryos, providing additional evidence for a close phylogenetic relationship between Thysanoptera and Psocoptera.