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At least 145 records · Page 8Linked to original sources

PubMed1991

Clinical and roentgenographic evaluation of hydroxyapatite-coated and uncoated porous total hip arthroplasty: a preliminary report.

Sixty osteoarthritic patients undergoing primary uncemented total hip arthroplasty were matched for age and weight and randomized into one of four groups with respect to implant coating and postoperative protected weight-bearing status: group 1, hydroxyapatite, 12 weeks; group 2, uncoated, 12 weeks; group 3, hydroxyapatite, 6 weeks; group 4, uncoated, 6 weeks. Tantalum spheres were implanted periprosthetically into the femur at the time of arthroplasty, thus providing constant references for stereoscopic radiographs. Patients were then evaluated over a 1-year period with clinical examination, plain radiography, and roentgen stereophotogrammetric analysis (RSA). Clinical evaluation using Charnley scoring showed no significant preoperative or postoperative intergroup differences, whereas visual analog testing noted less thigh pain with hydroxyapatite-coated stems at 12 weeks and 6 months follow-up. Plain radiographic analysis produced no significant differences, with no instability detected and bony ingrowth noted uniformly in all groups. The preliminary stereographic evaluation showed migration in all groups, but there were no significant differences between coated and uncoated stems or 6-week and 12-week partial weightbearing protocols. The Charnley, plain radiographic, and preliminary stereogrammetric evaluations all suggest that migration is unaltered by enhanced surfaces and that early unprotected weightbearing does not jeopardize implant fixation regardless of coating design. The lower incidence of visual analog thigh pain with the hydroxyapatite-coated stems, however, may be a reflection of bony ingrowth and as such add some validity to the theoretical advantages of enhanced surface prostheses.

Aged↗

PubMedDate not supplied

Long-term extracorporeal blood bypass in dogs at low flows without systemic heparinization. Heparin-coated versus uncoated circuits.

A blind, randomized study of the effects of a heparin-coated bypass circuit on thromboembolus formation and hematologic and hemostatic parameters was carried out on 12 dogs. The dogs were anesthetized and bypassed for 24 hours using a centrifugal pump circuit with a mean flow of 475 ml/minute. Six of the dogs were bypassed with a heparin coated circuit and six with an uncoated circuit. No systemic heparin was administered to any of the dogs at any time during the procedure. Both the coated and uncoated circuits remained patent at low flows. Thrombus formation, however, primarily around the pump axis, was observed in both groups. Four of the dogs (two from either group) had no evidence of lung emboli. The remaining eight dogs all showed pulmonary emboli. Thromboemboli did not lead to clinical complications or hemodynamic disturbances. Hematologic and hemostatic parameters showed a reduction in hemoglobin, erythrocytes, thrombocytes, leukocytes, and antithrombin III, which was most pronounced in the uncoated group. This study showed that a low flow bypass circuit remains patent for 24 hours whether or not the circuit is coated with heparin. Although the heparin coating limits the reduction in antithrombin III and blood elements, it does not eliminate the risk of thromboembolus formation.

Animals↗

PubMed1987

The ATPase core of a clathrin uncoating protein.

Chymotryptic digestion of bovine brain uncoating ATPase produced a 60-kDa fragment that was subsequently proteolyzed to 44 kDa. Loss of clathrin cage uncoating activity paralleled the conversion of the intact 70-kDa enzyme to the 60-kDa fragment, while clathrin binding activity was lost as the 60-kDa fragment was degraded to 44 kDa. This 44-kDa fragment has been purified to homogeneity and characterized as a clathrin-independent ATPase. The 44-kDa ATPase domain has been localized within the intact enzyme by the use of amino-terminal specific antibodies. This localization relates to the conserved nature of the 70-kDa heat shock protein family, of which bovine brain uncoating ATPase is a constitutively expressed member.

Adenosine Triphosphatases↗

PubMed1986

Selective externalization of an ATP-binding protein structurally related to the clathrin-uncoating ATPase/heat shock protein in vesicles containing terminal transferrin receptors during reticulocyte maturation.

Transferrin receptors are lost from reticulocytes in vesicles that are released during the final stage of erythrocyte maturation (Pan, B. T., and Johnstone, R. M. (1983) Cell 33, 967-977). Transferrin receptor-containing vesicles have a major protein component present in a 1:1 ratio with the receptor that migrates on sodium dodecyl sulfate gels as two polypeptides of Mr = 71,000 and 72,000. The Mr = 71,000/72,000 doublet is indistinguishable from the clathrin-uncoating ATPase/heat shock protein based on cross-reaction with affinity-purified antibody against the uncoating protein, by comparison of peptide maps of the Mr = 72,000 and 71,000 polypeptides and the uncoating protein, and by selective binding of these polypeptides to ATP-agarose. This finding suggests a possible activity of proteins related to the uncoating/heat shock protein family in the disposal of aged membrane proteins by a pathway independent of lysosomes.

Animals↗

PubMed1980

Comparative evaluation of coated and uncoated polyglactin 910 in cataract and muscle surgery.

This study describes the intraoperative and postoperative performance of coated and uncoated Polyglactin 910 in cataract and muscle surgery. The evaluation represents an animal and clinical comparison of 5-0 coated and uncoated Polyglactin 910 in 50 muscle cases and 7-0 coated and uncoated Polyglactin 910 in 150 cataract cases. Both Polyglactin 910 sutures provided high tensile strength, good knot security, batch-to-batch uniformity, ease of handling, minimal reaction, and a predictable absorption rate. Improvements noted in the coated suture were: (1) easier passage through tissue, (2) less chatter in tying, (3) fewer instances of premature tie, and (4) decreased tendency to incarcerate tissue.

Absorption↗

PubMed1981

Comparative bioavailability of sustained-release and uncoated aspirin tablets.

Plasma salicylate concentrations during multiple-dose administration of an uncoated and a sustained-release aspirin preparation were compared. Eight healthy adult subjects were given aspirin 2.6 g/day as sustained-release and uncoated tablets in two and four divided doses, respectively, for five-day periods in a crossover design. Treatment regimens were compared on the basis of five plasma salicylate concentrations measured during the fourth and fifth days of drug administration. Although there was considerable intersubject variation, no significant differences in salicylate concentrations (p less than or equal to 0.05) were found between treatments at any sampling time using the Wilcoxon signed-rank test or analysis of variance. Sustained-release aspirin preparations are capable of producing plasma salicylate concentrations comparable with those produced by uncoated aspirin tablets administered more frequently.

Adult↗

PubMed1994

A seven-year clinical evaluation of soft-tissue effects of hydroxylapatite-coated vs. uncoated subperiosteal implants.

Subperiosteal implants have been providing a treatment modality for the edentulous and partially edentulous patient for over 35 years. A recent innovation in subperiosteal dental implant materials technology is the use of hydroxylapatite (HA) coating as a surface coating on the implanted metal framework. The purpose of this study was to compare the intermediate-term soft-tissue performance of HA-coated subperiosteal dental implants with that of uncoated subperiosteal dental implants at equivalent time periods. Four choices of each implant variety were followed for approximately six years. At five years, one patient died, so one HA-coated implant was lost to further follow-up. One uncoated subperiosteal needed to be removed at four years, due to unremitting dehiscence around the post area. The remaining implants were followed, and results indicate that the early healing sequelae appear to be hastened and that the intermediate-term status is non-problematic for all implants. Hard-tissue reactions are not necessarily apparent by direct observation. The HA-coated implants were associated with a kinder soft-tissue response, typified by a tighter, healthier soft-tissue seal around the perigingival abutment posts and no post-implantation strut dehiscence complications. HA coating appears to represent an incremental increase in performance of uncoated metallic subperiosteal dental implants, for soft-tissue as well as hard-tissue response.

Aged↗

PubMed1985

Transport of horseradish peroxidase across monkey trophoblastic epithelium in coated and uncoated vesicles.

This study used membranous chorion of the macaque monkey placenta to examine uptake and processing of exogenous proteins. Tissue was incubated with either cationic or anionic horseradish peroxidase. Incubation time was varied between 5-25 min to follow the endocytic pathways. In spite of some differences in binding, uptake and processing of the isozymes was similar. In the presence of tracers at 37 degrees C both horseradish peroxidases were taken up in large (150-175) nm diameter) coated vesicles. In addition, coated tubules 300-400 nm in length and 50-100 nm in diameter were seen in the apical cytoplasm. Studies using ruthenium red indicated that the coated tubules were derived from long coated invaginations of the free surface that pinch off into the apical cytoplasm. Often, the tubules bud off small (85-105 nm diameter) protein-filled coated vesicles which traversed the cytoplasm and fused with the basal-lateral plasma membrane. In other cases, the tubules or vesicles lost their clathrin coats and fused to form larger endocytic vesicles which later fused with phagolysosomes. After long incubation, larger uncoated vesicles (endosomes) were seen releasing their contents at the basal-lateral membrane. These results suggest that multiple transport pathways exist in this epithelium. The first, involving only coated structures, may function to sort and concentrate specific ligands important for embryonic development. The second, involving the formation and translocation of large uncoated vesicles to the basal-lateral membrane, may also provide nutrients to the embryo. A third pathway directs the protein to phagolysosomes where it is presumably degraded.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid Phosphatase↗

PubMed2002

Catheter-related infection and thrombosis of the internal jugular vein in hematologic-oncologic patients undergoing chemotherapy: a prospective comparison of silver-coated and uncoated catheters.

BACKGROUND: Catheter-related venous thrombosis is one of the most frequent complications of central venous catheters (CVCs). This complication occurs in 4- 40% of patients with hematologic malignancies receiving conventional chemotherapy after placement of CVCs. METHODS: The objective of this prospective study was to assess whether a silver-coated CVC poses an additional risk in the development of catheter-related thrombosis in hematologic-oncologic patients. Patients were randomized to receive either silver-coated polyurethane catheters (BactiGuard; Metacot, Stockholm, Sweden) or uncoated standard polyurethane catheters (Cavatheter, Fresenius AG, Bad Homburg, Germany) for central venous access. Silver-coated catheters (n = 120) and standard catheters (n = 113) were inserted into the jugular vein in 233 consecutive patients. Variables that may be significant for the development of thrombosis were comparable in the two groups. After removal of the CVC, the patency of both jugularian veins internal as well as external was assessed with real-time ultrasound (Sonolayer-SAL-35A; Toshiba, Tokyo, Japan). RESULTS: Four of 233 patients (1.5%) were found to have venous thrombosis. Incomplete occlusion of the internal jugular vein occurred in 2 patients (0.75%, parietal thrombosis), and complete thrombosis, although clinically silent, was found in 2 patients (0.75%). There was no difference between patients with silver-coated and uncoated CVCs. CONCLUSIONS: The authors concluded that this novel silver-coated CVC does not cause a higher rate of central venous thrombosis compared with standard CVCs. The low overall incidence of central venous thrombosis might be attributed to the routine application of low-dose heparin in our patients during chemotherapeutic treatment.

Antineoplastic Agents↗

PubMed2004

Osteointegration of bioactive glass-coated and uncoated zirconia in osteopenic bone: an in vivo experimental study.

In elderly and osteoporotic patients an age-related loss of osteoinductivity could be the biological cause of implant failure regardless of the high quality of the implanted device. yttria stabilized tetragonal zirconia (YSTZ), either coated with the bioactive glass named RKKP bioglaze (RKKP) or uncoated, was implanted in the distal femurs of sham-operated and ovariectomized female rats. Animals were sacrificed at 30 and 60 days. Histomorphometry and microhardness tests were performed to assess osteointegration rate as well as bone quality around the implants. Significant decreases (p < 0.0005) in trabecular bone volume, BV/TV (41%), trabecular bone surface BS/TV (33%), trabecular thickness Tb.Th (20%), and trabecular number Tb.N (32%), together with a significant increase in trabecular separation Tb.Sp (184%), were found for the osteopenic rats compared with the sham-operated rats. At both experimental times the RKKP coating ensured a better osteointegration rate with higher AI values than the uncoated YSTZ, even when osteopenic rats were used (48% at 30 days and 12% at 60 days). No differences were observed at the bone-biomaterial interfaces for either material when comparing sham-operated with osteopenic rats. The present results demonstrate that the RKKP bioactive glass used as a coating ensures a high osteointegration rate even in osteoporotic bone, which is already visible from postoperative day 30 and is still apparent on day 60.

Animals↗

PubMed1989

Axonal transport of a clathrin uncoating ATPase (HSC70): a role for HSC70 in the modulation of coated vesicle assembly in vivo.

Clathrin plays an important role in many cellular processes, including endocytosis, secretion, and sorting of membranous organelles. Both the neuronal cell body and presynaptic terminals contain numerous coated vesicles, but few are detectable in the axonal regions that connect these two regions of the neuron. Clathrin heavy chains, light chains, and assembly proteins have all been shown to be axonally transported as part of slow component b (SCb). However, the paucity of coated vesicles present in the axon indicates the existence of a mechanism regulating clathrin coated assembly in vivo. A clathrin uncoating ATPase has been described that binds in stoichiometric amounts to clathrin and dissociates clathrin coats from vesicles in the presence of ATP in vitro. This clathrin uncoating ATPase is a major cytosolic protein of Mr 70 kD in bovine brain, forming 1% of soluble brain protein, and appears to be homologous with a constitutively expressed 70 kd heat shock protein (HSC70). We report here that a major 70 kD protein present in the SCb rate component of axonal transport is identical with HSC70 by both biochemical and immunochemical criteria. The cotransport of HSC70 with clathrin in SCb of axonal transport is consistent with a role for HSC70 in vivo in the regulation of clathrin function during axonal transport.

Adenosine Triphosphatases↗

PubMedDate not supplied

Imaging of immunolabeled membrane receptors in uncoated SEM specimens.

Epidermal growth factor receptors (EGFR) were labeled with 10 nm immunogold and examined on uncoated specimens of A431 human epidermoid carcinoma cells. A field emission gun and a high-sensitivity YAG ring detector were used to demonstrate the affinity labeling simultaneously in the secondary-electron (SE) and backscattered-electron (BSE) modes with a low accelerating voltage (Vo). At Vo = 2 kV, the SE and BSE signals were too weak to identify all markers, while at Vo = 3-7 kV labeling was observed unambiguously in both the SE and BSE modes with smaller and higher working distances. Increasing the Vo to above 7 kV sometimes provokes instability of the specimens. A Vo of > or = 10 kV produces charging artifacts in the SE image, but permits a BSE image of the gold markers providing additional topographic information. In conclusion, immunogold labeling can be used with good results for uncoated specimens.

Carcinoma, Squamous Cell↗

PubMed1999

Applications of short-chain polydimethylacrylamide as sieving medium for the electrophoretic separation of DNA fragments and mutation analysis in uncoated capillaries.

In capillary electrophoresis (CE), separation of DNA fragments is usually performed in covalently coated capillaries. Recent studies have demonstrated that certain polymers form a dynamic coating on the inner surface of the capillary, thereby suppressing the electroosmotic flow and DNA-capillary wall interactions. We developed a simple method for the synthesis of short-chain polydimethylacrylamide (PDMA) using isopropanol as a chain transfer agent. Capillary (<75 microm internal diameter) filling and replacement of this low-viscosity (14 cP at 4% PDMA) self-coating medium were easily carried out by commercial CE instruments. Using PDMA and uncoated capillaries, we first examined the separation of phi X174 HaeIII DNA digests and observed that the stability of the dynamic coating was markedly better at pH 7.8 than at pH 8.3. At this lower pH and nondenaturing conditions, high resolution of the phi X174 HaeIII DNA digests was obtained for more than 850 injections in the same capillary. We then exploited this sieving medium in CE using multiple approaches for mutation analysis of clinical DNA samples including separation of restriction enzyme cleavage products, analysis of single strand conformation polymorphisms, and simultaneous detection of several mutations using multiplex allele-specific PCR amplification. Our results demonstrate that CE in uncoated capillaries using PDMA as sieving medium is a simple, versatile, and reliable strategy for separation and mutation analysis of clinical DNA samples.

Acrylic Resins↗

PubMed1993

Attachment of neutralizing antibodies stabilizes the capsid of poliovirus against uncoating.

Poliovirus capsid is rapidly and irreversibly degraded upon treatment in hypotonic buffer at 37 degrees C. However, the attachment of neutralizing antibodies stabilized the virus capsid against degradation by similar treatment. This was demonstrated by the use of antisera to poliovirus from rabbits and other mammalian species. As shown with neutralizing antibodies, the degree of capsid stabilization paralleled the number of bound IgG molecules per virion and the rate of neutralization. Upon acid treatment virus-antibody complexes disaggregated and infectious virus was recovered. Divalent binding of antibodies to the virus surface has been suggested to be a prerequisite for neutralization by cross-linking subunits, thereby preventing virus uncoating. This reaction was mimicked by using chemical cross-linking with a bifunctional reagent. The introduction of intramolecular bridges between adjacent VP1 and VP3 polypeptides was accompanied by a marked drop in infectivity. The treated virus was still able to adsorb to and penetrate into HeLa cells. Physically, intact virus could be reisolated from infected cells, suggesting that the loss of infectivity was probably due to the inhibition of uncoating. Additionally, cross-linked virus was stabilized against treatment in hypotonic buffer. Cleavage of the cross-links by treatment with a reducing agent under mild conditions resulted in restoration of the infectivity.

Animals↗

PubMed1983

Bioavailability and pharmacokinetics of theophylline in plain uncoated and sustained-release dosage forms in relation to smoking habit. I. Single dose study.

The bioavailability and pharmacokinetics of theophylline from a plain uncoated and 2 newly designed, sustained-release tablet formulations, as compared to intravenous aminophylline, were studied in 12 healthy adult male volunteers. The subjects were divided into two groups (n = 6) with respect to smoking habit and on 4 separate occasions each received, on a randomized cross-over basis, a single dose of 400 mg equivalent of theophylline from every dosage form. The intravenous aminophylline study showed that habitual smoking had a significant (p less than 0.05) effect on plasma theophylline clearance (0.051 +/- 0.006 vs 0.035 +/- 0.004 l/kg/h). Smoking significantly reduced the raw AUC from the 4 dosage forms (p less than 0.05), but did not change the characteristics of absorption of each formulation. There was a non-significant trend towards reduced absolute bioavailability of theophylline from sustained-release formulations in smokers (percentage mean difference - 16% for one formulation and 13% for another). The trend was not observed for the plain uncoated tablet, which was rapidly absorbed (p less than 0.01 to 0.05 in Ka, tmax and Cmax compared to sustained-release tablets). Similarity of the in vitro dissolution profiles of the two sustained-release formulations did not imply similarity of the in vivo absorption characteristics. Plasma clearances of theophylline and antipyrine were significantly correlated (p less than 0.05, r = 0.693, n = 10). Thus, smoking enhanced the elimination of theophylline regardless of the dosage form administered. However, the extent to which habitual smoking may affect the hepatic first-pass effect on theophylline from sustained-release formulations requires further study. The results also suggest that theophylline and antipyrine may share a similar or common and presumably polycyclic hydrocarbon-inducible form(s) of microsomal drug-metabolizing enzyme.

Administration, Oral↗

PubMed1982

Uncoating-like modification of poliovirus capsid resulting from the cooperative effects of subfreezing temperature and submolar concentrations of urea.

Inactivation of poliovirus at subfreezing temperature in the presence of unusually low concentrations of urea (less than or equal to 0.5 M) was investigated. Whereas serotypes 1 and 2 are very sensitive, type 3 is resistant. Inactivation cannot be attributed to concentration of solutes since temperature must be reduced below -13 degrees C for loss of infectivity. Characteristics of the inactivated virion are similar to those of virions in the early stages of uncoating in HeLa cells, viz., loss of infectivity, sensitivity to proteases and detergents, change in isoelectric point, retention of intact genome, and in some instances, loss of VP4. The molecular basis for inactivation is considered to be dissociation of water bound to capsid proteins thereby causing irreversible denaturation of native tertiary structure. The results of this study are discussed in terms of their relevance to the early stages of uncoating in vivo.

Adsorption↗

PubMed1983

The uncoating of paramyxoviruses may not require a low pH mediated step.

The effect of lysosomotropic agents, chloroquine and NH4Cl, on the replication of paramyxoviruses was compared with that on the other enveloped RNA viruses whose uncoating is known to be blocked by the agents. Under the conditions where vesicular stomatitis or influenza virus infection was strongly inhibited at an early step, the agents exhibited little inhibitory effect on the progress of infection by Newcastle disease virus and Sendai virus, allowing viral primary transcription to occur and neither inhibiting the virus production significantly nor reducing the number of infected cells. These results are incompatible with the previous report showing that paramyxovirus and the other enveloped RNA viruses may have in common an intracellular step sensitive to lysosomotropic agents (Miller and Lenard, Proc. Nat. Acad. Sci. USA 78, 3605-3609, 1981) and suggest that paramyxovirus uncoating may not require a low pH mediated lysosomal step.

Ammonium Chloride↗

PubMed1990

Inhibition of uncoating of tobacco mosaic virus particles in protoplasts from transgenic tobacco plants that express the viral coat protein gene.

The uncoating of tobacco mosaic virus (TMV) particles in protoplasts isolated from leaves of transgenic tobacco plants that express the TMV coat protein gene was investigated. Extracts of these protoplasts collected up to 1 hr after inoculation with TMV contained fewer of the complexes ("striposomes") thought to be involved in cotranslational disassembly of virus particles than did extracts of protoplasts that do not express the viral coat protein gene. These results are consistent with the hypothesis that TMV coat protein-mediated resistance is at least in part the result of inhibition of the uncoating of the virus particles in the inoculum.

Capsid↗