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PubMed1990

Termini of Salmonella flagellin are disordered and become organized upon polymerization into flagellar filament.

The terminal regions of Salmonella flagellin are essential for polymerization to form the flagellar filament. It has recently been suggested, on the basis of results from circular dichroism spectroscopy and scanning calorimetry, that these regions are disordered in solution. We report here direct evidence for disorder and mobility in the terminal regions of flagellin using 400 MHz proton nuclear magnetic resonance (n.m.r.) spectroscopy. Comparison of the n.m.r. spectra of monomeric and polymeric flagellin shows that the terminal regions become organized when polymerized to form the filament.

Bacterial Proteins↗
PubMed1988

Calcium mobilization, actin polymerization and right-angle light scatter responses to leukotriene B4, 12(R)- and 12(S)-hydroxyeicosatetraenoic acid in human neutrophils.

The presence of microgram quantities of 12(R)-hydroxyeicosatetraenoic acid (12(R)HETE) in psoriatic scales has been reported. 12(R)HETE has been found to be 5-10 times more potent than its isomer 12(S)HETE in inducing neutrophil locomotion and aggregation. In this study, the ability of these two eicosanoids to elicit a mobilization of calcium and a polymerization of actin was examined and compared to that of leukotriene B4. These two cell-biochemical assays were chosen in view of the likelihood that they are relevant to the motile functions of the neutrophils. 12(R)HETE was found to induce an increase in the cytoplasmic level of free calcium and in the amount of polymerized actin. 12(S)HETE also raised the level of free calcium, though to a lesser extent than 12(R)HETE, but did not induce a detectable polymerization of actin. Leukotriene B4 was more active, on the basis of concentration and maximal response, than either 12(R)HETE or 12(S)HETE. The activity of 12(R)HETE detected and reported in this communication provides support for the suggestion that this eicosanoid may play a significant role in the pathogenesis of the inflammatory reactions in psoriasis.

Actins↗
PubMed1990

Effects of bile acids on actin polymerization in vitro.

Bile acids are major determinants of canalicular bile secretion, and there are indications that choleretic bile acids increase bile canalicular contractions, in isolated rat hepatocytes. Therefore, we examined the influence of various bile acids on the rate of actin polymerization in vitro. The free forms of cholic acid, ursodeoxycholic acid, and chenodeoxycholic acid, as well as their taurine and glycine conjugates, were incubated with purified muscle actin, at a concentration of 100-300 nmoles/mg actin. The rate of actin polymerization was measured by viscometry and the fluorescence of the pyrene probe, linked to actin. Results showed that all bile acids slow the rate of polymerization, and that the effect was dose-dependent. However, the reduction by chenodeoxycholic acid was greater than that caused by the other bile acids. The results indicate that bile acids, particularly in high concentrations interact with actin, a finding that may be related to the increased bile canalicular contractility, and altered canalicular membrane morphology, induced by choleretic bile acids.

Actins↗
PubMed1983

The effect of toxin from Leiurus quinquestriatus scorpion venom on the polymerization and stability of microtubules.

The venom of the scorpion Leiurus quinquestriatus, well-known for its actions on voltage-sensitive sodium channels, has now been shown to have pronounced effects on the in vitro polymerization and stability of neuronal microtubules purified by temperature-dependent cycles of assembly and disassembly. The crude venom, at concentrations as low as 100 micrograms/ml, alters both the extent of tubulin polymerization, as monitored by turbidity, and the appearance of polymerized material under electron microscopic examination. Structures formed in the presence of the venom retain the temperature sensitivity characteristic of normal microtubules, but respond to calcium ions abnormally with a dispersal of ordered structures, as reflected by both increased light scattering and electron microscopic analysis. Fractionation of the crude venom suggested that the active component was the same as the polypeptide neurotoxin which interacts with voltage-sensitive sodium channels and this identity was subsequently verified. Thus, the effect on microtubules of highly purified L. quinquestriatus sodium channel toxin obtained from an independent source was indistinguishable from that of the crude venom. These results indicate that the sodium channel toxin from L. quinquestriatus is also a potent cytoskeletal agent in vitro. This finding may be related to the growing body of evidence suggesting that the neuronal cytoskeleton plays a functional role in the maintenance of membrane excitability.

Animals↗
PubMed1984

Inhibition or acceleration of fibrin polymerization by monoclonal immunoglobulins and immunoglobulin fragments.

A prolongation of the thrombin clotting time by at least 25% was found in the presence of 8 of 26 IgG myeloma proteins, 2 of 5 IgA proteins and 1 of 10 macroglobulins, in a concentration of 10 mg/ml. Normal pooled immunoglobulin in concentrations up to 83 mg/ml were inactive. 2 IgG and 2 IgM monoclonal immunoglobulins caused an acceleration of the thrombin time by at least 20%; this phenomenon has not been reported before. Corresponding results were obtained with these proteins when the polymerization of des-AA and des-AABB fibrin monomers were investigated in a light scattering system. Studies with enzymatically produced Fab, F(ab')2 and Fc fragments from normal and monoclonal immunoglobulin suggested that the polymerization inhibitory activity resides in the Fab portion of the immunoglobulin molecule. While the ability to inhibit fibrin polymerization may be an immunoglobulin specific effect, the acceleration caused by certain other monoclonal immunoglobulins may be an unspecific effect similar to that seen with dextran or albumin.

Animals↗
PubMed1985

Fibrinogen Baltimore IV: congenital dysfibrinogenemia with delayed fibrin monomer polymerization.

A congenital dysfibrinogenemia, fibrinogen Baltimore IV, has been found in a 56-year-old Caucasian man. Clinical laboratory studies disclosed a slightly prolonged prothrombin time, but were otherwise unremarkable. Release of fibrinopeptides by thrombin occurs normally, as does ligation of the fibrin polymer by Factor XIII. Approximately half of the isolated fibrin monomers polymerize normally, but the remainder polymerize at about 2% of the initial rate. The functional defect is thus limited to a decrease in the rate of fibrin monomer polymerization.

Afibrinogenemia↗
PubMed1988

Pressure influences the rate of fibrin polymerization: decompression accelerates, compression decelerates.

We report here that the rate of fibrin polymerization is accelerated by decompression: the rate is essentially doubled by reducing the pressure by one-half (380 torr, 14.7 PSI or 1/2 ATM) and increased by 3.6 times with respect to the control at 25 torr (0.48 PSI or 1/30th ATM). We also report here that the rate of fibrin polymerization is decelerated by compression; at 5.2 X 10(5) torr (10,000 PSI or 680 ATM) polymerization is inhibited and/or reversed.

Animals↗
PubMed1976

Polymerized ragweed antigen E. IV. The analysis of the stability of molecular size and antigenic reactivity of the polymer.

Ragweed antigen E polymerized by treatment with glutaraldehyde offers a potentially improved method for immunotherapy of human IgE-mediated pollinosis because studies have demonstrated that the polymer retains antigenic reactivity but has decreased ability to release histamine when these functions are compared on a weight basis. The potential clinical usefulness of the polymer is dependent both on stability of the polymer and on retention of antigenic reactivity. The method used for the analysis of the stability of the polymer under conditions of storage was the comparison of gel filtration fractionation profiles. No depolymerization was demonstrated during storage conditions for 2 mo, and only minimal evidence of additional polymerization (less than 8%) or depolymerization (less than 7%) was observed after 6 mo of storage. There was no difference in the per cent of polymerized antigen E precipitated by rabbit antiserum after storage as compared with control samples.

Antigens↗
PubMed1977

Polymerization of mixtures of grass allergens.

Mixed grass pollen allergens were precipitated from crude grass extract by 90% saturation with ammonium sulfate. The precipitate was dissolved and polymerized with glutaraldehyde. Polymerized allergens with a molecular weight range of 200,000 to 4,000,000 were isolated. The resultant grass allergen polymers had reduced allergenicity but were capable of absorbing out IgG antibody from sera of 2 patients treated with crude grass allergens. This alteration of allergenicity was intended to reduce the ability of allergens to react with IgE-sensitized cells rather than to modify or destroy antigenic determinants. Prior exposure of allergens to phenol used as a preservative inhibited the polymerization process probably by blocking combining sites with which glutaraldehyde reacts.

Allergens↗
PubMed1981

Further studies on the safety of polymerized antigens for immunotherapy.

Six patients receiving immunotherapy with standard aqueous extracts for the treatment of atopic disease were selected from the patient population of Northwestern University Allergy Clinics for continued immunotherapy with polymerized antigens. These six patients could not tolerate quantities of conventional aqueous extracts considered maintenance doses because of immediate-type local or systemic allergic reactions or both to immunotherapy. These six patients were treated with separate preparations of polymerized ragweed (PRW) and polymerized grass (PG), and each of the six patients was rapidly advanced to previously unobtainable maintenance doses of PRW and PG without local or systemic reactions. Treatment with other aeroallergen standard extracts was continued to maintenance dosage without further systemic reactions. In patients highly sensitive to ragweed and grass aqueous extracts, the substitution of these extracts with PRW and PG allows these patients to receive therapeutic immunotherapy injections with decreased risk of immediate-type local and systemic reactions.

Adult↗
PubMed1985

Brief report: evaluation of polymerized ragweed extracts by intradermal end point titration, RAST inhibition, and parallel line bioassay.

We have evaluated six polymerized ragweed extracts on the basis of RAST inhibition, parallel line bioassay, and intradermal end point titration. The results of the parallel line bioassay and intradermal end point titration are highly correlated (r = 0.995, df = 2, p less than 0.01). Both intradermal end point titration (r = 0.973, df = 4, p less than 0.01) and parallel line bioassay (r = 0.985, df = 2, p less than 0.05) are highly correlated with RAST inhibition. We have evaluated the utility of intradermal end point titration as a quantitative assay of relative allergenicity of polymerized extracts. The between assay reproducibility was derived by comparing a reference polymerized ragweed extract against itself. The 99% confidence limits of relative allergenicity were 53% to 188% when four assays were used. This compares favorably to the published 99% confidence limits of the parallel line bioassay 60% to 166% when three assays were used. Intradermal end point titration is highly reproducible, is highly correlated with RAST inhibition or parallel line bioassay, and thus is an appropriate bioassay of allergenic activity.

Allergens↗
PubMed1986

Safety and immunogenicity of immunotherapy with polymerized tree, grass, and ragweed in patients with multiple inhalant sensitivities.

Immunotherapy with polymerized ragweed (PRW) and individually polymerized grasses (IPG) previously has been demonstrated to be safe and effective. We conducted this trial in order to assess safety and immunogenicity of individually polymerized trees (IPT) and to assess safety of concomitantly administering IPT, IPG, and PRW in patients with multiple inhalant sensitivities. Sixteen patients with typical tree pollinosis were recruited; all but one had grass pollinosis, and all had ragweed pollinosis. Patients were treated in 12 weekly visits with allergens to which they were sensitive, 48,850 PNU of IPT; 2668 AU (50,000 PNU) of PRW; and 48,850 PNU of IPG. There were no systemic reactions and no changes in laboratory parameters, including renal and hepatic functions with injections. Blood was drawn for immunologic studies before and after the injection series. There were significant rises in IgG titers by ELISA to each tree allergen administered, oak, elm, and box elder. There were significant rises in total antibody binding of ragweed AgE and rye grass group I in patients treated with PRW and IPG, respectively. Changes in IgE to oak, elm, box elder, AgE, and rye grass group I were minimal. In summary, IPT is safe, immunogenic, and can be administered concomitantly with PRW and IPG in patients with multiple inhalant sensitivities.

Blood Proteins↗
PubMed1988

Comparison of parallel line skin test assay (PLST) and ELISA inhibition (EI) methods for determination of relative potency of polymerized grass and ragweed antigenic extracts.

Relative potency estimates were performed by parallel line skin test assay (PLST) and ELISA inhibition methods for three polymerized allergen extracts (Bermuda grass, orchard grass, and a copolymer of short and giant ragweed) versus four unmodified RAST standardized reference extracts (Bermuda grass, orchard grass, and giant and short ragweed) in nine subjects. One subject experienced a systemic reaction, requiring treatment at the end of the PLST assay. Another subject had a systemic reaction during limited skin testing performed approximately 72 hours after completion of PLST. Relative potency values for the polymerized extracts obtained by PLST were much lower than those obtained by ELISA inhibition, but results were significantly (r = 0.95; p less than 0.01) correlated. Because polymerized allergen extracts are designed to be hypoallergenic, a skin test assay may underestimate their potency relative to an unmodified reference extract.

Binding, Competitive↗
PubMed1992

Synthesis and polymerization of new expanding dental monomers.

The objective of this work was to develop polymeric materials that expand slightly upon polymerization and that could potentially be used as matrix resins for dental composites. A series of stereoisomeric alicyclic spiroorthocarbonates (SOC's) that expand when polymerized were synthesized. Three of these SOC racemates were analyzed: cis/cis-, cis/trans- and trans/trans-2,3,8,9-di(tetramethylene)-1,5,7,11-tetraoxaspiro[5.5] undecane. The degrees of expansion, approximately 3.9% and 3.5%, for the cis/cis and trans/trans, were determined by measuring the specific volume of the monomers and polymers in dilute solutions. This method of determining densities and subsequent calculated expansion or shrinkage was validated by duplicating the reported shrinkage of 4-tert-butylphenyl glycidyl ether, styrene, and methyl methacrylate. Based on these data and spectral data obtained using other analytical techniques, these stereoisomeric alicyclic SOC's appear to have potential as nonshrinking polymer or copolymer matrices for dental composites.

Chromatography, Gas↗
PubMed1992

Effect of phenolic compounds on the polymerization of methyl methacrylate.

The inhibitory effects of six phenolic compounds and two analogues on the polymerization of methyl methacrylate (MMA) by azobisisobutyronitrile (AIBM) were examined. Differential scanning calorimetry was used to determine the induction period (IP) and initial rate of polymerization (IRP). The IP values (minutes) decreased in the order: eugenol > thymol > hydroquinone > cresol > guaiacol > phenol >>> safrole > methol. The IRP values of all compounds tested ranged from 0.8 to 1.2 percent per minute, except for hydroquinone (0.2 percent per minute). Phenolic compounds inhibited the polymerization of MMA by scavenging radicals, and eugenol was the most potent inhibitor.

Cresols↗
PubMed1993

Measuring polymerization shrinkage of photo-activated restorative materials by a water-filled dilatometer.

A water-filled dilatometer specifically designed for determining the polymerization shrinkage of photo-activated composite restorative materials was used to measure the polymerization shrinkage of three visible light-activated composites. Polymerization shrinkage values ranged from 1.82% for P-50 to 2.15% and 2.19% for Herculite XRV and Prisma APH, respectively. Shrinkage data obtained in this investigation were compared with the published data, and the factors which affect shrinkage measurements were reviewed. It was concluded that maintaining a constant temperature environment (+ or - 0.02 degrees C) for the dilatometer during the shrinkage test was the most critical factor for successful application of the dilatometer.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1993

True linear polymerization shrinkage of unfilled resins and composites determined with a linometer.

A device, which was given the name "linometer", has been developed for measuring linear polymerization shrinkage of both unfilled resins and composites. The results were in agreement with those obtained with the mercury dilatometer. The present method is simple, fast, insensitive to temperature fluctuations, is operational at any temperature and, if desired, samples can be maintained in a 100% relative humidity environment. The linometer offers an easy means for routine polymerization shrinkage determinations and therefore may be useful in evaluating new monomer systems for dental composites. The linear polymerization shrinkage for several unfilled resins and composites was measured with this device.

Acrylic Resins↗
PubMed1986

Characterization of plasma polymerized polypropylene coatings.

Propylene was polymerized at low pressure in a radio frequency plasma reactor. The plasma polymerized propylene (PPP) films were insoluble in toluene. Thermal analysis of PPP showed no phase transition took place up to 255 degrees C. From these results, it was concluded that PPP is a highly crosslinked polymer. To further characterize the deposited PPP, Fourier Transform infrared (FTIR) spectroscopy in the attenuated total reflection (ATR) mode was used. The deposited material was shown to be polymerized propylene as a spectrum of the material showed absorption bands characteristic of polypropylene.

Biocompatible Materials↗