PubMed Health⌕ Search

Biomedical subjects

S Holly

Publications and source records attributed to S Holly.

18 recordsLinked to original sources
PubMed2000

Effect of chain length on the conformation and T cell recognition of synthetic hemagglutinin fragments.

Circular dichroism and Fourier-transform infrared spectroscopies were used to compare the conformational mobility of 13-mer peptides covering the 317-329 region of the envelope protein hemagglutinin of human influenza A virus subtypes H1, H2 and H3 with that of their truncated deca- and nonapeptide analogs. These peptides were demonstrated to bind to the murine I-Ed major histocompatibility complex encoded class II and human HLA-B*2705 class I molecules. Despite the amino acid substitutions in the three 13-mer subtype sequences, no significant differences in the conformational properties could be shown. Deletion of the N-terminal three residues resulted in a shift to an increased alpha-helical conformer population in the 317-329 H1 peptide and the breakage of the 3(10) or weakly H-bonded (nascent) alpha-helix in the H2 and H3 peptides. The conformational change observed upon deletion did not influence the efficiency of I-Ed peptide interaction, however, the C-terminal Arg had a beneficial effect both on MHC class II and class I binding without causing any remarkable change in solution conformation.

Animals↗
PubMed1999

Quantitative studies on the respiratory burst generated in peritoneal macrophages.

The luminol-dependent chemiluminescence of macrophages during the zymosan-stimulated respiratory burst has been studied both in the absence and in the presence of the radical inhibitor 3,5 di-tert-butyl-4-hydroxyphenyl propionic acid. In addition, the consumption of luminol and of the inhibitor has been followed analytically. Based on the rates of the consumption of the inhibitor, an iteration procedure yields a value of 2.2 x 10(-7) M for the steady-state concentration of radicals generated by cells at the maximum of the chemiluminescence in the presence of inhibitor. Approximate calculations have indicated that under the experimental conditions applied, additional formation of superoxide anion radicals by the oxidation of luminol is negligible. By assuming that in an inhibitor-free system the disappearance of radicals takes place via their combination process as well as by their interaction with luminol and/or with luminol-derived species, numerical integration yields a calculated curve of radical concentration versus time in fair agreement with experimental data and a rate-constant value for the combination of radicals of approximately 10(6) M-1 s-1, supporting literature findings according to which primarily superoxide anion radicals are formed.

Animals↗
PubMed1998

New acetylenes isolated from the bark of Heisteria acuminata.

Five new linear acetylenic compounds, namely, pentadeca-6,8,10-triynoic acid (1), octadeca-8,10,12-triynoic acid (2), trans-pentadec-10-en-6,8-diynoic acid (3), cis-hexadec-11-en-7,9-diynoic acid (4), and cis-octadec-12-en-7,9-diynoic acid (5), were isolated from the bark of Heisteria acuminata by bioassay-guided fractionation, using cyclooxygenase (COX) and 5-lipoxygenase (5-LO) assays as models for antiinflammatory activity. The structures of compounds 1-5 were established by NMR, MS, IR, and Raman spectroscopy. These isolated compounds were found to be potent inhibitors of COX. Compounds 4 and 5 were the most potent inhibitors of 5-LO, whereas the other compounds only showed a weak inhibition at the same concentration.

Acetylene↗
PubMed1995

Mapping the intersubunit region of influenza virus hemagglutinin: comparative CD and FTIR spectroscopic studies on multiple antigenic peptides.

An A/PR/8/34 (IHN1) influenza virus hemagglutinin (HA)-specific monoclonal antibody (Z38) was found to react with the solid phase adsorbed influenza virus expressing uncleaved (HA0) molecules but not to bind to virus particles bearing enzymatically cleaved hemagglutinin. Synthetic peptides corresponding to the uncleaved HA0 317-341 intersubunit region of subtypes H1-H3 (IP1-IP3) or comprising either the C-terminal 317-329 amino acids of HA1 (CP1) or the N-terminal 330-341 of HA2 (fusion peptide, FP) subunits of cleaved HA were used to characterize the fine specificity of Z38 mAb. Circular dichroism and Fourier-transform infrared spectroscopy showed that, compared to IP2 and IP3 comprising the H2 and H3 subtype fragments of the intact intersubunit region, IP1 has relatively low helicity but a tendency to adopt beta-turns in trifluoroethanol. The immunological and conformational properties of multiple antigenic peptides (MAPs) containing four copies of CP1 were also studied. Based on the appearance of an infrared component band at 1637 cm-1 (beta-turn band), the CP1 arms of MAPs also contain repeats of beta-turns. However, it is only the MAP1-FP construct comprising also the fusion peptide, which binds Z38 mAb as strongly as IP1 does. This puts emphasis on the role of the fusion region in modifying conformation and consequently the ability of peptides to elicit an antibody response. The results obtained for peptide conformation also suggests a beta-turn(s)/beta-sheet/beta-turn/beta-sheet conformational motif in the recognition by the hemagglutinin subtype-specific Z38 monoclonal antibody or by peptide-induced polyclonal antibodies.

Amino Acid Sequence↗
PubMed1995

Complexes of aluminium with peptide ligands: a Fourier transform IR spectroscopic study.

Aluminium has been recognized to be a neurotoxic agent and a risk factor in Alzheimer's disease and other neuronal dysfunctions. CD spectroscopic studies on two synthetic fragments of the human neurofilament protein midsized subunit (NF-M), and their alanine-for-serine-substituted and/or serine-phosphorylated derivatives showed the formation of stable, citric acid resistant complexes of Al3+ with peptide ligands [M. Hollósi, Z. M. Shen, A. Perczel, and G. D. Fasman (1994) Proc. Natl. Acad. Sci. USA, vol. 9, pp. 4902-4906]. In the case of Ser-phosphorylated fragments, a beta-sheet inducing effect of Ca2+ and Al3+ ions was observed. However, the serine-containing parent peptides, NF-M13 (KSPVPKSPVEEKG) and NF-M17 (EEKGKSPVPKSPVEEKG), failed to show CD spectral changes reflecting beta-sheet formation upon addition of Al3+ ions. On the basis of the amide I region of the Fourier transform ir spectra, in trifluoroethanol, the peptide backbone of NF-M17 and NF-M17 (A6A11) shows marked changes in the presence of Al3+. The most significant spectral differences are seen in the carboxyl region (> 1700 cm-1). The high-frequency component bands above 1760 cm-1 in both spectra belong to the C = O of undissociated CF3COOH. Another strong band at 1710 cm-1 which appears only in the spectrum of NF-M17 (A6A11)(NF-M17 with Ser6 and Ser11 replaced by Ala) can be assigned to the side chain or C-terminal COOH groups. The differential protonation state of the carboxyl groups in the two peptides suggests the formation of Al3+ complexes of different structure and stability.(ABSTRACT TRUNCATED AT 250 WORDS)

Aluminum↗
PubMed1994

Conformational mapping of amyloid peptides from the putative neurotoxic 25-35 region.

The secondary structure of amyloid beta A(25-35) and its deletion analogues was studied by circular dichroism (CD), Fourier transform infrared (FTIR) spectroscopy and molecular dynamics calculation. Data of our comparative CD and FTIR measurements in trifluoroethanol suggest that beta A(25-35)NH2 has a preferred beta-sheet conformation. Contrary to this beta A(31-35)NH2 tends to adopt a beta-turn conformation. Based on the comparable neurotoxic effect of beta A(25-35)NH2 and beta A(31-35)NH2 the neurotoxicity likely involves the same 31-35 core sequence and the "biologically active conformation" is a beta-turn rather than a beta-sheet structure.

Amino Acid Sequence↗
PubMed1994

CD and Fourier transform ir spectroscopic studies of peptides. II. Detection of beta-turns in linear peptides.

Comparative CD and Fourier transform ir (FTIR) spectroscopic data on N-Boc protected linear peptides with or without the (Pro-Gly) beta-turn motif (e.g., Boc-Tyr-Pro-Gly-Phe-Leu-OH and Boc-Tyr-Gly-Pro-Phe-Leu-OH) are reported herein. The CD spectra, reflecting both backbone and aromatic contributions, were not found to be characteristic of the presence of beta-turns. In the amide I region of the FTIR spectra, analyzed by self-deconvolution and curve-fitting methods, the beta-turn band showed up between 1639 and 1633 cm-1 in trifluoroethanol (TFE) but only for models containing the (Pro-Gly) core. This band was also present in the spectra in chloroform but absent in dimethylsulfoxide. These findings, in agreement with recent ir data on cyclic models and 3(10)-helical polypeptides and proteins in D2O [see S. J. Prestrelski, D. M. Byler, and M. P. Thompson (1991), International Journal of Peptide and Protein Research, Vol. 37, pp. 508-512; H. H. Mantsch, A. Perczel, M. Hollósi, and G. D. Fasman (1992), FASEB Journal, Vol. 6, p. A341; H. H. Mantsch, A. Perczel, M. Hollósi, and G. Fasman (1992), Biopolymers, Vol. 33, pp. 201-207; S. M. Miick, G. V. Martinez, W. R. Fiori, A. P. Todd, and G. L. Millhauser (1992), Nature, Vol. 359, pp. 653-655], suggest that the amide I band, with a major contribution from the acceptor C = O of the 1<--4 intramolecular H bond of beta-turns, appears near or below 1640 cm-1, rather than above 1660 cm-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1993

FT-IR spectroscopy indicates that Ca(2+)-binding to phosphorylated C-terminal fragments of the midsized neurofilament protein subunit results in beta-sheet formation and beta-aggregation.

The Fourier-transform infrared (FT-IR) spectra in trifluoroethanol (TFE) of phosphorylated peptides, NF-M17(Ser6P) and NF-M17(Ser11P) representing the C-terminal repeating domain of the midsized neurofilament protein subunit (NF-M) have been measured. In the absence of Ca2+ ions both phosphopeptides adopt predominantly aperiodic conformation with minor amounts of beta-turns, 3(10) helix or beta-pleated sheet. Addition of Ca(ClO4)2 results in opaque solutions, and in the case of the Ser6P peptide, precipitation. The infrared spectra of the supernatants reflect the presence of unordered and beta-sheet structure. The infrared spectrum of the solid Ca(2+)-complex of NF-M17 (Ser6P) in a KBr pellet shows amide component bands at 1654 (alpha-helix or loops) and 1626.5 cm-1 (beta-sheet). The high intensity of the beta-sheet component suggests extensive beta-aggregation. The data reported herein give an infrared spectroscopic support to our previous findings that upon Ca2+ binding, phosphorylated NF-M fragments undergo a marked conformational change which gives rise to partial beta-sheet formation and beta-aggregation. This observation may have relevance to the molecular events which lead to the accumulation of abnormal proteineous structures in Alzheimer's disease.

Amino Acid Sequence↗
PubMed1993

Circular dichroism and Fourier-transform infrared spectroscopic studies on T-cell epitopic peptide fragments of influenza virus hemagglutinin.

Epitopic peptides representing the C-terminal (HA1) region of cleaved hemagglutinin of influenza virus from different serotypes were synthesized. Circular dichroism and Fourier-transform infrared spectroscopic data showed that peptides HS2 and HS3 have a predominantly alpha-helical conformation in trifluoroethanol. Recently a component band appearing between 1640 and 1635 cm-1 in the amide I region of the Fourier-transform infrared spectra of polypeptides has been correlated with strongly H-bonded beta-turns (Ref. 8). Using this assignment, HS1 was found to contain less alpha-helix but have tendency to adopt beta-turn(s). Interestingly, fragment HS2 with the highest alpha-helix content proved to be the poorest T-cell epitope among serotypes HS1-HS3.

Amino Acid Sequence↗
PubMed1993

ATP induces a conformational change of the 90-kDa heat shock protein (hsp90).

The 90-kDa heat shock protein (hsp90) is a well conserved, abundant cytosolic protein believed to be a "chaperone" of most steroid receptors. We have recently demonstrated that hsp90 has an ATP-binding site and autophosphorylating activity (Csermely, P., and Kahn, C. R. (1991) J. Biol. Chem. 266, 4943-4950). Circular dichroism analysis of highly purified hsp90 from rat liver shows that ATP induces an increase of beta-pleated sheet content of hsp90. Vanadate, molybdate, and heat treatment at 56 degrees C induce a similar change in the circular dichroism spectrum. Fourier transformed infrared spectroscopy reveals an ATP-induced increase in the interchain interactions of the 90-kDa heat shock protein due to an increase in its beta-pleated sheet content. In further studies we found that ATP: 1) decreases the tryptophan fluorescence of hsp90 by 11.6 +/- 1.9%; 2) increases the hydrophobic character of the protein as determined by its distribution between an aqueous phase and phenyl-Sepharose; and 3) renders hsp90 less susceptible to tryptic digestion. Our results suggest that hsp90 undergoes an "open-->closed" conformational change after the addition of ATP, analogous in many respects to the similar changes of the DnaK protein, the immunoglobulin heavy chain binding protein (BiP/GRP78), and hsp70. The ATP-induced conformational change of hsp90 may be important in regulating its association with steroid receptors and other cellular proteins.

Adenosine Triphosphate↗
PubMed1988

Surgical spectrum of aortic stenosis in children: a thirty-year experience with 257 children.

Aortic stenosis accounts for 5 to 6% of infants and children seen for surgical repair of congenital heart disease. The clinical presentation and reported results of operation for aortic stenosis are highly variable. This retrospective review was undertaken to assess our operative mortality and the degree of gradient reduction afforded by each of several surgical techniques used to treat aortic stenosis in children over a 30-year period. Two hundred fifty-seven patients ranging in age from 1 day to 19 years were operated on between 1957 and 1986. The indication for operation included asymptomatic patients with gradients greater than 50 mm Hg to patients in profound cardiogenic shock. The operative mortality for children older than 6 months was 4%, whereas neonates seen with critical aortic stenosis had a 60% mortality. The late mortality was 2%. Eighty percent of surviving patients to date have undergone cardiac catheterization after repair. This shows an overall reduction of 57 mm Hg in the left ventricular-aortic gradient. Patients with supravalvular aortic stenosis and discrete subvalvular aortic stenosis as well as patients undergoing aortic valve replacement showed a reduction in or elimination of associated aortic insufficiency, whereas patients undergoing aortic valvotomy or neonates having valvotomy had a significant increase in demonstrable aortic insufficiency. The incidence of third-degree heart block or cerebral emboli following operation for aortic stenosis was less than 1%. However, the incidence of late bacterial endocarditis following repair was nearly 5%; six of eleven cases occurred in the group with discrete subvalvular aortic stenosis. Twenty-nine (13%) of the 223 long-term survivors have undergone a subsequent procedure for relief of residual or recurrent obstruction; 12 have had insertion of an aortic valve prosthesis, 12 have had insertion of an apicoaortic conduit, and 6 have required repeat aortic valvotomy. These data demonstrate the low operative mortality and excellent hemodynamic benefit of surgical relief of single-level aortic stenosis in children older than neonates. Conduits placed for complex obstructions or operative procedures in neonates have acceptable hemodynamic benefits, but operative mortality remains high.

Adolescent↗
PubMed1987

Metabolism of flumecinol in humans.

1. The metabolism of 14C-flumecinol (3-trifluoromethyl-alpha-ethyl-benzhydrol) was studied in volunteers after a single oral dose of 100 mg (11.1 MBq; 300 microCi). Radioactivity excreted in urine was 78.8 +/- 6.0% of dose and in faeces was 12.0 +/- 5.3% dose in 120 h. 2. Unchanged flumecinol was not excreted in urine, but was present in faeces unconjugated (1.2% dose) and as conjugates of glucuronic and sulphuric acids (10.8% dose). 3. Enzymic hydrolysis showed that all urinary metabolites were conjugated with glucuronic and/or sulphuric acids (77.8% dose). Unconjugated urinary metabolites were not found. 4. The major route of flumecinol metabolism was hydroxylation of the alkyl side chain and/or the phenyl group followed by conjugation. 5. Both the CF3-group and the skeleton of the original compound remained intact during metabolism.

Adult↗
PubMed1979

Metabolism of mesocarb in the rat.

1. Rats treated orally with [14C]mesocarb (I; 3-(1-methyl-2-phenyl[2-(14C]ethyl)-N-(phenylaminocarbonyl)sydnone imine) (50 mg/kg) excrete 35% of the radioactivity in 24 h urine and 51% in 48 h urine. 2. Only traces of unchanged drug were found in urine. Hydroxy-mesocarb (II), dihydroxy-mesocarb (III), amphetamine (VII) and the conjugates of II and III account for 86% of the urinary radioactivity. 3. Cannulated male rats excrete about 40% of the radioactivity in 30 h in bile, mainly as conjugates of II and III.

Amphetamine↗
PubMed1978

Metabolism of 14C-3-trifluoromethyl-alpha-ethylbenzhydrol in rats.

Metabolism of 3-trifluoromethyl-alpha-ethyl-benzhydrol (I), hepatic enzyme inducer has been studied in rats. Five metabolites in bile and four in urine, as well as minute amounts of the original drug (I) were identified. The only major metabolite in bile and one of the two major metabolites in urine were found to be aromatic hydroxylated products of I, i.e., 3-trifluoro-methyl-4'-hydroxy-alpha-ethylbenzhydrol (II). The results of enzymatic hydrolysis with beta-glucuronidase/arylsulfatase suggest that hydroxyl groups of metabolites are conjugated. Considering the structure of metabolites isolated a probable order of metabolite formation is outlined.

Animals↗