SEARCH · PubMed Health

Results for “Addition chains”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 901 records · Page 50Linked to original sources

PubMed2006

Cervicitis and genitourinary symptoms in women culture positive for Mycoplasma genitalium.

PROBLEM: Mycoplasma genitalium has been associated with male urethritis. We sought to relate M. genitalium to genitourinary signs and symptoms in women. METHOD OF STUDY: We compared 26 culture-positive women (group 1), 257 additional polymerase chain reaction-positive women (group 2), and 107 negative control women. We used logistic regression to evaluate signs and symptoms, controlling for co-infections, pregnancy, age, and intervention group assignment. RESULTS: Comparing group 1 with controls, we found significantly elevated odds ratios (ORs) for intermediate vaginal discharge (OR = 5.4; 95% confidence interval 1.01, 29.2) and action in response to discharge [3.9 (1.1, 13.5)]. Non-significant increases were observed for pathologic vaginal discharge [3.8 (0.78, 18.2)], pathologic dyspareunia [1.5 (0.25, 9.0)], vaginal odor [2.1 (0.75, 5.7)], and cervical mucopus [4.1 (0.74, 22.4)]. Group 2 results were similar, but showed no increase in cervical mucopus relative to controls. CONCLUSION: Infection with M. genitalium in women is independently related to increased genitourinary symptomatology.

Adolescent↗

PubMed2004

Focal epithelial hyperplasia (Heck's disease): report of two cases with PCR detection of human papillomavirus DNA.

Focal epithelial hyperplasia (FEH) (Heck's disease) is essentially a benign oral infection produced by the human papillomavirus (HPV). Although this condition is known to exist in numerous populations and ethnic groups, it is relatively rare in South-East Asia. The following report is based on two cases of adult FEH with histopathological features in favour of the disease. In addition, polymerase chain reaction was performed to detect the presence of HPV DNA in the lesions in order to confirm the histopathological diagnosis.

Adult↗

PubMed1990

Stability of the nucleotide sequence of the phosphoprotein gene of measles virus during lytic infections.

Three clones with cDNA inserts encoding large portions of the measles virus phosphoprotein mRNA were characterized and compared with a previously published sequence of the Edmonston strain of measles virus. The two cloned viruses were separated by more than 100 passages. Only one out of 1477 nucleotides differed in the two sequences reflecting a very low mutation rate of the phosphoprotein gene during dilute lytic passages. The discovery that a third reading frame in the phosphoprotein gene may code for a novel peptide chain in addition to the P and C peptides may explain some of the high stability of the gene. The new reading frame was accessed by a translational shift caused by insertion of one extra G at a particular site in one of three otherwise identical cDNA sequences. A discrepancy was also found between the presumably high error rate of viral RNA polymerases and the stability of nucleotides in which mutations would not lead to amino acid substitutions. A few errors in the previously published sequence were discovered and the corrections are presented.

Base Sequence↗

PubMed1978

Interaction of cortisol-21-palmitate with liposomes examined by differential scanning calorimetry.

Liposomes have been suggested as carriers for corticosteroids in the local treatment of arthritis by intra-articular injection. The long chain 21-esters of cortisol such as the palmitate or octanoate are taken up and retained by liposomes in higher concentration than cortisol itself. Differential scanning calorimetry has been used to show that the cortisol ester is anchored in the liposome phospholipid bilayer by the acyl side chain. In addition, the limiting concentration of cortisol-21-palmitate which can be incorporated into dipalmitolyl phosphatidylcholine liposomes has been measured by observing changes in the DSC spectrum at different steroid concentrations. Steroid in excess of this concentration limit forms a separate phase which can be identified by nuclear magnetic resonance. For optimum effect, the treatment of arthritis with liposomes must be carried out with liposomes containing steroid below the limiting concentration.

Arthritis, Rheumatoid↗

PubMed2005

Photoinduced plasticity in cross-linked polymers.

Chemically cross-linked polymers are inherently limited by stresses that are introduced by post-gelation volume changes during polymerization. It is also difficult to change a cross-linked polymer's shape without a corresponding loss of material properties or substantial stress development. We demonstrate a cross-linked polymer that, upon exposure to light, exhibits stress and/or strain relaxation without any concomitant change in material properties. This result is achieved by introducing radicals via photocleavage of residual photoinitiator in the polymer matrix, which then diffuse via addition-fragmentation chain transfer of midchain functional groups. These processes lead to photoinduced plasticity, actuation, and equilibrium shape changes without residual stress. Such polymeric materials are critical to the development of microdevices, biomaterials, and polymeric coatings.

3-Mercaptopropionic Acid↗

PubMed1992

Augmentation of the antibacterial activity of magainin by positive-charge chain extension.

Novel analogs of the broad-spectrum antimicrobial peptide magainin-2 were obtained by extension of its chain through addition of segments of positively charged amino acids to either its N or its C terminus and by increasing its helicity. The activity of magainin-2 toward American Type Culture Collection strains of Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus was most considerably enhanced by these modifications, whereas, in general, its low hemolytic capacity was not or was only slightly affected. The antibacterial potencies of magainin-2 and its derivatives were more evident following decreases of pH from 7.2 to 6 and 5.

Amino Acid Sequence↗

PubMed1986

Degradation of soluble laminin and depletion of tissue-associated basement membrane laminin by Pseudomonas aeruginosa elastase and alkaline protease.

Purified Pseudomonas aeruginosa elastase and alkaline protease rapidly cleaved soluble laminin, with each enzyme yielding different cleavage products. These cleavage fragments were separated from the intact laminin A and B polypeptide chains by sodium dodecyl sulfate-polyacrylamide gradient gel electrophoresis and detected by their characteristic Coomassie blue staining patterns. Pseudomonas elastase produced rapid and extensive degradation of both A and B chains, including the disulfide-rich regions. Apparently complete degradation to limit digests was obtained after 30 min with a substrate/enzyme ratio of 30:0.5. Under similar conditions, alkaline protease rapidly degraded the A chain while slowly degrading the B chain. In addition, immunoreactive laminin was released from authentic basement membranes after incubation with either enzyme as detected by an enzyme-linked immunoabsorption assay and by immunofluorescence. The results from these studies suggest a direct role for elastase and alkaline protease in both tissue invasion and hemorrhagic tissue necrosis in P. aeruginosa infections.

Animals↗

PubMed1989

Interaction of drug resistance plasmids and bacteriophages with diarrheagenic strains of Escherichia coli.

Seven transfer-derepressed plasmids from different incompatibility groups in Escherichia coli K-12 were tested for their ability to enter 43 strains of diarrheagenic E. coli (mostly enteropathogenic E. coli clinical isolates) representing 12 serogroups and including rough and semirough mutants (characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis). Strains in some serogroups were more competent as recipients of plasmids than were those in others. Five test plasmids in an E. coli K-12 (rough) donor transferred significantly less efficiently to two smooth strains than to their rough or semirough isogenic derivatives. When the same smooth and rough strains were used as donors, the plasmids transferred to E. coli K-12 equally well. These results suggested that the O-antigenic lipopolysaccharide side chains of diarrheagenic E. coli isolates shielded the outer membrane receptors for conjugative pili, thus preventing plasmid entry. The different receptors for eight bacteriophages were also covered by O side chains. In addition, a limited survey of clinical isolates for drug resistance markers and resident plasmids was carried out.

Antigens, Bacterial↗

PubMed1990

Localization of host immunoglobulin G to the surface of Pneumocystis carinii.

In immunoblotting studies of Pneumocystis carinii surface proteins, we found that a secondary antibody, anti-human immunoglobulin G (IgG), recognized a 52-kilodalton (kDa) band in homogenates of P. carinii purified from human autopsy lungs and bronchoalveolar lavage fluids, even when serum as a source of primary antibody was omitted. The electrophoretic mobility of the 52-kDa band is identical to that of IgG heavy chains. In addition to affinity-purified, anti-human IgG, monoclonal antibodies specific for the Fab and Fc regions of human IgG recognized the 52-kDa band. To determine whether the 52-kDa band represents IgG bound to the surface of P. carinii, we treated intact organisms with Triton X-100 and acid in order to elute immunoglobulin from the surface of P. carinii. After purification over a protein G column, the eluate comigrated with human IgG, was recognized by anti-IgG, and bound to discrete bands with molecular sizes of 65 to 70, 60, 50, and 35 kDa in purified, rat-derived P. carinii. To confirm the presence of human IgG on the surface of P. carinii, we performed immunocytochemical and immunoelectron microscopic studies. Staining of intact P. carinii aggregates by anti-human IgG was pronounced and was abolished by acid treatment. IgA was also present. Ultrastructural studies showed the presence of IgG on the cyst wall and on fine membranous structures and vesicles adjacent to cysts. We conclude that the surface of P. carinii is coated with human IgG. The close association of human IgG with P. carinii may have implications for the pathogenesis of P. carinii pneumonia in acquired immunodeficiency syndrome.

Acquired Immunodeficiency Syndrome↗

PubMed2003

PaeX, a second pectin acetylesterase of Erwinia chrysanthemi 3937.

Erwinia chrysanthemi causes soft-rot diseases of various plants by enzymatic degradation of the pectin in plant cell walls. Pectin is a complex polysaccharide. The main chain is constituted of galacturonate residues, and some of them are modified by methyl and/or acetyl esterification. Esterases are necessary to remove these modifications and, thus, to facilitate the further degradation of the polysaccharidic chain. In addition to PaeY, the first pectin acetylesterase identified in the E. chrysanthemi strain 3937, we showed that this bacterium produces a second pectin acetylesterase encoded by the gene paeX. The paeX open reading frame encodes a 322-residue precursor protein of 34,940 Da, including a 21-amino-acid signal peptide. Analysis of paeX transcription, by using gene fusions, revealed that it is induced by pectic catabolic products and affected by catabolite repression. The expression of paeX is regulated by the repressor KdgR, which controls all the steps of pectin catabolism; by the repressor PecS, which controls most of the pectinase genes; and by catabolite regulatory protein, the global activator of sugar catabolism. The paeX gene is situated in a cluster of genes involved in the catabolism and transport of pectic oligomers. In induced conditions, the two contiguous genes kdgM, encoding an oligogalacturonate-specific porin, and paeX are both transcribed as an operon from a promoter proximal to kdgM, but transcription of paeX can also be uncoupled from that of kdgM in noninduced conditions. PaeX is homologous to the C-terminal domain of the Butyrivibrio fibriosolvens xylanase XynB and to a few bacterial esterases. PaeX contains the typical box (GxSxG) corresponding to the active site of the large family of serine hydrolases. Purified PaeX releases acetate from various synthetic substrates and from sugar beet pectin. The PaeX activity increased after previous depolymerization and demethylation of pectin, indicating that its preferred substrates are nonmethylated oligogalacturonides. PaeX is mostly found in the periplasmic space of E. chrysanthemi. These data suggest that PaeX is mainly involved in the deacetylation of esterified oligogalacturonides that enter the periplasm by the KdgM porin.

Amino Acid Sequence↗

PubMed2005

Characterization of a human H5N1 influenza A virus isolated in 2003.

In 2003, H5N1 avian influenza virus infections were diagnosed in two Hong Kong residents who had visited the Fujian province in mainland China, affording us the opportunity to characterize one of the viral isolates, A/Hong Kong/213/03 (HK213; H5N1). In contrast to H5N1 viruses isolated from humans during the 1997 outbreak in Hong Kong, HK213 retained several features of aquatic bird viruses, including the lack of a deletion in the neuraminidase stalk and the absence of additional oligosaccharide chains at the globular head of the hemagglutinin molecule. It demonstrated weak pathogenicity in mice and ferrets but caused lethal infection in chickens. The original isolate failed to produce disease in ducks but became more pathogenic after five passages. Taken together, these findings portray the HK213 isolate as an aquatic avian influenza A virus without the molecular changes associated with the replication of H5N1 avian viruses in land-based poultry such as chickens. This case challenges the view that adaptation to land-based poultry is a prerequisite for the replication of aquatic avian influenza A viruses in humans.

Adaptation, Physiological↗

PubMed2005

Complete loss of Ndel1 results in neuronal migration defects and early embryonic lethality.

Regulation of cytoplasmic dynein and microtubule dynamics is crucial for both mitotic cell division and neuronal migration. NDEL1 was identified as a protein interacting with LIS1, the protein product of a gene mutated in the lissencephaly. To elucidate NDEL1 function in vivo, we generated null and hypomorphic alleles of Ndel1 in mice by targeted gene disruption. Ndel1(-/-) mice were embryonic lethal at the peri-implantation stage like null mutants of Lis1 and cytoplasmic dynein heavy chain. In addition, Ndel1(-/-) blastocysts failed to grow in culture and exhibited a cell proliferation defect in inner cell mass. Although Ndel1(+/-) mice displayed no obvious phenotypes, further reduction of NDEL1 by making null/hypomorph compound heterozygotes (Ndel1(cko/-)) resulted in histological defects consistent with mild neuronal migration defects. Double Lis1(cko/+)-Ndel1(+/-) mice or Lis1(+/-)-Ndel1(+/-) mice displayed more severe neuronal migration defects than Lis1(cko/+)-Ndel1(+/)(+) mice or Lis1(+/-)-Ndel1(+/+) mice, respectively. We demonstrated distinct abnormalities in microtubule organization and similar defects in the distribution of beta-COP-positive vesicles (to assess dynein function) between Ndel1 or Lis1-null MEFs, as well as similar neuronal migration defects in Ndel1- or Lis1-null granule cells. Rescue of these defects in mouse embryonic fibroblasts and granule cells by overexpressing LIS1, NDEL1, or NDE1 suggest that NDEL1, LIS1, and NDE1 act in a common pathway to regulate dynein but each has distinct roles in the regulation of microtubule organization and neuronal migration.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗

PubMed1988

Measurement of branched chain amino acids in blood plasma by high performance liquid chromatography.

A simple and rapid high performance liquid chromatographic technique is described for the separation and quantitation of plasma branched chain amino acids. After addition of a norleucine internal standard, plasma samples are acidified with acetic acid, and amino acids are separated from proteins and other plasma components by passage of the acidified plasma through an ion exchange resin. The ammonium hydroxide eluate from the resin is dried, phenylisothiocyanate derivatives are prepared, and the amino acids are separated on a Waters reverse-phase "Pico-Tag" column with an ultraviolet detector set at 254 nm. In addition to the branched chain amino acids (leucine, valine, and isoleucine), aspartate, glutamate, serine, threonine, alanine, and methionine are quantitated with high precision and accuracy, as verified by quantitative recovery and comparison with an automatic amino acid analyzer. The advantages of the method are its simplicity, speed, stability of derivatives, high reproducibility, low per-sample cost, and the use of a simple fixed-wavelength ultraviolet detector.

Amino Acids, Branched-Chain↗

PubMed1994

Smooth muscle contraction kinetics at different calcium concentrations.

Actin-myosin interaction kinetics of the intact rat portal vein were studied by analyzing force recovery after cessation of force-inhibiting length vibration. The time constant of postvibration force recovery averaged 0.86 +/- 0.04 s during short-term activation (< 12 s), and increased up to 1.59 +/- 0.02 s (cross-bridge downregulation) during sustained activation of more than 10 min. After the depletion of intracellular calcium stores, the depolarized preparation developed maximum force at an extracellular calcium concentration in excess of 50 mM CaCl2. The time constant of postvibration force recovery rose to 12.31 +/- 1.35 s after an activation period of 30 min. These retarded contraction kinetics may be caused either by low activation of the 20-kDa myosin light chain kinase or by high activity of the 20-kDa myosin light chain phosphatase. Addition of the phosphatase inhibitor okadaic acid (10 microM) during high calcium activation decreases the time constant to 8.04 +/- 0.86 s and appears to prevent the distinct retardation of the contraction kinetics. During submaximum activation (2.5 mM CaCl2), the time constant of postvibration force recovery stabilizes at 1.56 +/- 0.07 s, indicating downregulated cross-bridge kinetics, and is unaffected by phosphatase inhibition. For maximum barium activation, instead of calcium, 19.5 mM BaCl2 is required, which produced time constants of postvibration force recovery of 8.38 +/- 0.32 s. The addition of okadaic did not affect contraction kinetics during barium activation. The pronounced retardation of contraction kinetics that was observed after the maximum calcium activation of the previously calcium depleted, depolarized preparation is probably due to high phosphatase activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Actins↗

PubMed2005

Amphiphilic telechelic poly(N-isopropylacrylamide) in water: from micelles to gels.

We report the first study of aqueous solutions (0.025 gL(-1) to 46 gL(-1)) of a telechelic poly(N-isopropylacrylamide) with octadecyl termini (C(18)-PNIPAM-C(18), M(w): 37000, 320 NIPAM units, M(w)/ M(n)=1.07) obtained by reversible addition-fragmentation chain transfer (RAFT) free radical polymerization of N-isopropylacrylamide. Static and dynamic light scattering measurements and fluorescence spectroscopy, using 8-anilino-1-naphthalenesulfonic acid (ANS) as probe, yielded the concentration dependence of the size and aggregation number of C(18)-PNIPAM-C(18) micelles in cold ( 20( degrees )C) dilute aqueous solutions. Concentrated solutions ( c>20 gL(-1)) form transient gels exhibiting an oscillatory shear behavior that can be approximated by a single-relaxation Maxwellian model. Aqueous solutions of C(18)-PNIPAM-C(18) undergo a phase transition upon heating to 31.5( degrees )C as determined by microcalorimetry. The heat-induced phase separation of dilute (0.025 gL(-1)) C(18)-PNIPAM-C(18) solutions yields a fluid that is colloidally stable at temperatures higher than 33( degrees )C. The overall results are consistent with a model assuming the formation of flowerlike micelles in the dilute regime and a network of micelles connected by telechelic chains in the concentrated regime.

Journal Article↗

PubMed1990

Myosin light chain phosphorylation in human myometrial smooth muscle cells.

Ca2+/calmodulin-dependent phosphorylation of the 20-kDa regulatory light chain of myosin is of signal importance in the initiation of contraction in a number of smooth muscle tissues. In this investigation, we evaluated the relationship between intracellular free Ca2+/concentration [( Ca2+]i) and the extent of myosin light chain phosphorylation in cultured human myometrial smooth muscle cells. Treatment of myometrial cells with ionomycin caused a concentration- and time-dependent increase in [Ca2+]i and phosphorylation of myosin light chain. Temporally, the increases in light chain phosphorylation and [Ca2+]i in response to ionomycin were similar. In myometrial cells treated with ionomycin (10(-5) M) for 10 s, [Ca2+]i increased from 138 to 800 nM; in these same cells, myosin light chain phosphorylation increased from 5% to a maximum value of 54%. Half-maximal phosphorylation of myosin light chain was attained at 300 nM [Ca2+]i. Treatment of myometrial smooth muscle cells with prostaglandin (PG) F2 alpha (10(-8) M) and PGE2 (10(-8) M) caused a proportionate increase in [Ca2+]i and myosin light chain phosphorylation. In addition, [Ca2+]i and myosin light chain phosphorylation increased in response to oxytocin and angiotensin II. These findings indicate that a number of uterotonic agents effect an increase in [Ca2+]i, which in turn causes phosphorylation of myosin light chain. Furthermore, the concentration of Ca2+ in the cytoplasm is a primary determinant for myosin light chain phosphorylation in human myometrial smooth muscle cells.

Angiotensin II↗

PubMed1993

ANG II- or AVP-induced increases in protein synthesis are not dependent on autocrine secretion of PDGF-AA.

Previous studies have demonstrated that angiotensin II (ANG II) and arginine vasopressin (AVP) stimulate increased protein synthesis and cellular hypertrophy in cultured rat aortic smooth muscle cells (SMC). The aim of this study was to explore the hypothesis that ANG II- and/or AVP-induced increases in protein synthesis are mediated by autocrine secretion of platelet-derived growth factor (PDGF)-AA. Results demonstrated that ANG II or AVP increased expression of PDGF-A, but not -B, chain mRNA. Additionally, conditioned media from ANG II- and AVP-treated SMC had increased mitogenic activity for Swiss 3T3 cells, which could be inhibited with a neutralizing antibody to PDGF-AA. However, PDGF-AA-neutralizing antibodies did not inhibit ANG II- or AVP-induced increases in protein synthesis, and exogenous PDGF-AA did not stimulate increased protein synthesis. Furthermore, no PDGF-alpha receptors were evident based on 125I-labeled PDGF-AA binding studies. In summary, results indicate that ANG II- or AVP-induced increases in protein synthesis were not dependent on autocrine secretion of PDGF-AA.

Angiotensin II↗

PubMed1989

Novel abnormality in subpopulations of circulating lymphocytes. T gamma delta and CD2-, 3+, 4-, 8- lymphocytes in histoplasmosis-associated immunodeficiency.

A patient, who had developed anergy after disseminated histoplasmosis and who had gone on to develop a cardiomyopathy, demonstrated an unusually large proportion of T lymphocytes bearing the gamma and delta chains of the T cell receptor (TCR-gamma/delta). These gamma delta + cells composed over half of the circulating lymphocytes and were clearly divisible into two subgroups based on the level of expression of the gamma and delta chains and their ability to bind one of the monoclonal antibodies reactive with the TCR-delta chain. In addition, the patient showed an abnormally high proportion of circulating lymphocytes having the CD2-, 3+, 4-, 8- phenotype which has been only recently described. The pattern of lymphocyte subpopulations changed over the 9 years that the patient was followed since his original infection and appears to characterize a novel abnormality.

Antibodies, Monoclonal↗