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Biomedical subjects

F Kueppers

Publications and source records attributed to F Kueppers.

At least 55 records · Page 3Linked to original sources
PubMed1983

Protease production by Pseudomonas aeruginosa isolates from patients with cystic fibrosis.

The temporal appearance of extracellular proteases produced by Pseudomonas aeruginosa was analyzed by pH 9 and pH 4 polyacrylamide gel electrophoresis (PAGE) and sodium dodecyl sulfate-PAGE. Ammonium sulfate precipitates of culture supernatants from various stages of growth revealed a time-dependent increase in number and amount of proteolytically active proteins. One mucoid P. aeruginosa clinical isolate and its derived nonmucoid variant, as well as two other nonmucoid variant P. aeruginosa strains (all from cystic fibrosis patients), showed similar production of five differently migrating proteases (P1 to P5, numbered according to increasing net negative charge) in pH 9 PAGE and one protease in pH 4 PAGE. P2, P3, and P5 increased to maximum concentrations at 24 to 48 h, decreasing thereafter, whereas P4 continued increasing even at 83 h, and P1 fluctuated. P3 was identified as an elastase. P2 was possibly composed of polypeptide chains bridged by disulfide bonds, since without reduction it migrated in sodium dodecyl sulfate-PAGE as a single protein, and with reduction it migrated as three protein bands. Two-dimensional PAGE revealed multiple molecular weight species within protease-positive bands in pH 9 gel strips. Isoelectric focusing gave a pattern of protein separation that correlated with two-dimensional PAGE analysis. Thus, greater heterogeneity of active proteases than previously reported has been demonstrated in all P. aeruginosa clinical isolates studied by sensitive two-dimensional PAGE analysis.

Cystic Fibrosis↗
PubMed1983

Protease inhibitors in tracheobronchial secretions.

The isolation and characterization of three protease inhibitors from tracheobronchial secretions are described. As starting material, pooled secretions from patients with tracheostomies was used. The isolation procedure consisted of precipitation with 3% perchloric acid (the major acid-stable inhibitors remain in solution), affinity chromatography on trypsin-Sepharose, and preparative zone electrophoresis. We found three distinct inhibitors. One was a basic protein with evidence of size and charge heterogeneity but immunologic homogeneity, Mr = 15,850 +/- 1200 daltons, 12,600 +/- 700, 6500 +/- 500. Two inhibitors were acidic proteins, Mr = 63,400 +/- 3200 (AI) and 19,960 +/- 1500 (AII) daltons. The basic inhibitor had tyrosine as the sole aminoterminal amino acid. For the two acidic inhibitors, an aminoterminus was not found. All three inhibitors contained neutral sugars and amino sugars but no sialic acid. They inhibit trypsin, chymotrypsin, and human granulocytic elastase. The two acidic inhibitors are immunologically related; they are apparently derived from serum ITI. Inhibitor AII originates from inhibitor AI, probably by limited proteolysis by several proteases. The concentration of the basic inhibitor in bronchial secretions of 42 patients with obstructive lung disease was 0.206 +/- 0.15 mg/ml.

Alpha-Globulins↗
PubMed1981

Alpha-1-antitrypsin (Pi) types in Korean and Chinese populations.

Alpha-1-1-antitrypsin phenotypes were determined by isoelectric focusing in 270 Koreans and 52 Chinese. The frequencies of the major alleles were the following, numbers for the Chinese sample are in parentheses: PiM1: 0.65 (0.66), PiM2: 0.22 (0.25), PiM3: 0.06 (0.09). Other alleles, including PiZ were present in low frequencies. The Koreans appear to be quite similar to the Chinese in this system.

Adolescent↗
PubMed1981

Serum concentrations of vitamin D-binding protein (group-specific component) in cystic fibrosis.

Vitamin D-binding protein (DBP) concentrations were determined in the sera of 90 cystic fibrosis homozygotes, 57 obligate heterozygotes, and 46 normal controls. Very significantly lower mean concentrations were found in the sera of CF homozygotes compared with both heterozygotes and controls (P less than 0.01, Wilcoxon Rank Sums Test). Subdivision of the samples by Gc phenotype showed that this relationship held true both in the Gc1 and Gc2-1 phenotypes. The small sample size of the Gc2 genotype makes the significance levels of limited usefulness, but the pattern of variation of DBP levels among CF homozygotes, heterozygotes, and controls was consistent with that observed for the Gc1 and Gc2-1 classes. Haptoglobin levels showed high coefficients of variation when compared among CF homozygotes, obligate heterozygotes, and controls, presumably because of nonspecific elevation in the acute-phase response. Alpha 2-macroglobulin levels were, if anything, slightly elevated in CF homozygotes compared with controls, while albumin levels showed no significant mean differences between these groups. Since the DBP concentration does not vary with age nor with levels of vitamin D and its metabolites, we interpret our results to mean that DBP levels are specifically decreased in cystic fibrosis, perhaps as the result of impaired glycosylation of the protein.

Adolescent↗
PubMed1981

Angiotensin converting enzyme concentrations in rabbits with talc-induced pulmonary granulomas.

Pulmonary foreign body granulomas were induced in rabbits by intravenous injection of a talc suspension, and serum angiotensin converting enzyme (ACE) concentrations were monitored for 50 days. One of 3 treated rabbits responded with a slight elevation of serum ACE in the third week after the first injection and for the remainder of the experimental period. Two treated rabbits and 2 control rabbits maintained serum ACE concentrations close to the starting values throughout the observation period of 50 days. We concluded that pulmonary talc granulomas and probably other foreign body granulomas do not elicit a major elevation of serum ACE in rabbits.

Animals↗
PubMed1980

Enzymatic trimethylation of residue-72 lysine in cytochrome c. Effect on the total structure.

A highly purified protein methylase III from Neurospora crassa or Saccharomyces cerevisiae specifically methylates a single lysine residue of position 72 of horse heart cytochrome c. The enzymatically methylated cytochrome c has been separated from the unmethylated counterpart species by isoelectric focusing. Simultaneously, the pI values of these two species were found to be 9.49 and 10.03, respectively. Since methyl substitution increases the basicity associated with the epsilon-amino group of lysine residues, the observed decrease in pI value is in opposition to the predicted increase. Space-filling models revealed the possibility of a hydrogen bond between the oxygen of amide of residue-70 asparagine and the epsilon-amino nitrogen of residue-72 lysine in unmethylated horse heart cytochrome C. the enzymatic methylation of residue-72 lysine tends to dissociate this hydrogen bond, thereby possibly inducing the shift of 'effective charge' of the protein molecule. This paper also deals with the pI values of cytochromes c from 13 different sources, determined by the isoelectric focusing technique.

Animals↗
PubMed1980

Transferrin C subtypes in US blacks and whites.

Transferrin C is genetically heterogeneous. Isoelectric focusing in a pH gradient of 4.0-6.5 reveals two subtypes of transferrin C, TfC1 and TfC2, that differ slightly in their isoelectric point. The three transferrin bands seen in homozygotes (double bands for heterozygotes) probably represent different degrees of iron saturation. The most cathodal band consists of apotransferrin and the anodal band is fully saturated diferric transferrin. Family data are consistent with a codominant allelic mode of inheritance. The allele frequencies in US whites were 0.8 for TfC1 and 0.19 for TfC2; in US blacks the frequencies were 0.84 and 0.11, respectively. The concentrations of transferrin are probably the same for the three common phenotypes.

Black People↗
PubMed1980

Trypsin binding activity of alpha 2-macroglobulin in cystic fibrosis and other lung diseases.

Abnormalities of the interaction between alpha 2-macroglobulin and proteases have been suspected in cystic fibrosis. We measured the binding activity for trypsin of alpha 2-macroglobulin in 65 patients with cystic fibrosis, 41 obligate heterozygotes for cystic fibrosis, 18 children with asthma, 21 adult patients with chronic obstructive pulmonary disease, and 21 healthy control subjects. The assay was based on the observation that, once it is bound to alpha 2-macroglobulin, trypsin is no longer inhibited by soybean trypsin inhibitor. The bound trypsin retains activity against synthetic substrates such as N-alpha-benzoyl-arginine-p-nitroanilide. We found a moderately increased molar binding ratio of trypsin to alpha 2-macroglobulin in all patient groups and heterozygotes compared to healthy control subjects. The absolute concentration of alpha 1-macroglobulin was related to age rather than to the disease of the patient. Our data argue against a defect in protease-binding activity of alpha 2-macroglobulin in cystic fibrosis. The moderately increased binding activity observed could have been related to a structural difference in alpha 2-macroglobulin or to binding of ligands. This finding however, was not unique to patients with cystic fibrosis; the binding activity was increased in heterozygotes and in patients with other pulmonary diseases.

Adolescent↗
PubMed1980

Identification and separation of secreted platelet proteins by isoelectric focusing. Evidence that low-affinity platelet factor 4 is converted to beta-thromboglobulin by limited proteolysis.

Low-affinity platelet factor 4 and beta-thromboglobulin are low molecular weight platelet secretory proteins that have common antigenic determinants. Four amino acids (Asn-Leu-Ala-Lys) at the amino terminus of beta-thromboglobulin are deleted, but the remaining sequences of the two peptides appear to be identical. Low-affinity platelet factor 4 and beta-thromboglobulin have respective isoelectric points at pH 8.0 and at pH 7.0. Identification, quantitation, and separation of both proteins was achieved by a method combining preparative isoelectric focusing and specific radioimmunoassay with anti-low-affinity platelet factor 4 antibody. It has been determined that the supernate processes immediately after platelet aggregation induced by ionophore A23187 or thrombin contains approximately 80% low-affinity platelet factor 4, 8% beta-thromboglobulin, and 12% highly cationic immunoreactive material (platelet basic protein). Experimental evidence suggests that low-affinity platelet factor 4 is originally secreted by platelets and then converted to beta-thromboglobulin by a platelet-derived, heat-labile protease that is inhibited by phenylmethylsulfonyl fluoride.

Amino Acid Sequence↗