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H Bergstrand

Publications and source records attributed to H Bergstrand.

12 recordsLinked to original sources
PubMed1978

Partial purification and characterization of cyclic nucleotide phosphodiesterases from human bronchial tissue.

DEAE-Sephadex chromatography reveals the presence in extracts of human bronchial tissue of at least three separate cyclic nucleotide phosphodiesterases: a cyclic GMP-specific high affinity enzyme, a non-specific low affinity enzyme, and a high affinity cyclic AMP-specific enzyme. The activity of each fraction was partially characterized with respect to kinetic parameters, thermal stability, and the influence of a number of inhibitors. Each activity was found to resemble the activity of the previously characterized corresponding enzyme from whole lung tissue extracts. A high affinity non-specific phospho-diesterase previously isolated from lung tissue is missing in extracts of bronchial tissue.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1978

Cyclic nucleotide phosphodiesterase. Partial purification and characterization of a high affinity enzyme activity from human lung tissue.

Part of the soluble cyclic nucleotide phosphodiesterase activity of crude human lung tissue can be attributed to a thermosensitive (37 degrees) enzyme with a high apparent affinity for both adenosine 3':5'-monophosphate (cyclic AMP) and guanosine 3':5'-monophosphate (cyclic GMP). The enzyme can be partially purified by DEAE-Sephadex chromatography. In the presence of 0.1 mM EDTA or ethylene glycol bis(beta-aminoethyl ether)N,N'-tetraacetic acid (EGTA), it is eluted from the column immediately before a cyclic GMP-specific phosphodiesterase, but in the presence of 0.2 mM Ca2+, the elution follows that of the cyclic GMP-specific enzyme. The two forms of the nonspecific phosphodiesterase activity are referred to as DEAD-Sephadex Fractions Ia and Ic, respectively. Their apparent molecular weights, recorded at gel filtration, vary with different preparations from 230,000 to 150,000. Occasionally, corresponding recordings for main peaks of activity also cluster round the values 120,000, 105,000, and 78,000. The enzymatic properties of Fractions Ia and Ic closely resemble each other. The enzyme activity is blocked by EDTA, partially inhibited in the presence of 1,10-phenanthroline, but only slightly affected by EGTA. The inhibitory effect of EDTA can be overcome by Mg2+ and Mn2+ and that of 1,10-phenanthroline, in part, by Zn2+; this cation in itself is inhibitory at millimolar concentrations. With submicromolar substrate concentrations, the activity of either fraction obeys linear kinetics displaying an apparent Km of approximately 0.4 micron for both substrates. Reciprocal inhibition experiments suggest that hydrolysis of both cyclic AMP and cyclic GMP is performed by the same active site. Examination of the activity using extended substrate concentration ranges indicates nonlinear kinetics; Hill plots of such data also show nonlinear curvature. The activity is inhibited by micromolar concentrations of inosine 3':5'-monophosphate (cyclic IMP), 3-isobutyl-1-methylxanthine, papervine, and some antiallergic agents. Theophylline and disodium cromoglycate are less potent inhibitors. Inhibition of activity by Lubrol PX follows a biphasic dose response curve. The activity of Fraction Ia can be enhanced 2- to 3-fold by a Ca2+-dependent activator prepared from lung tissue, whose action is counteracted by chlorpromazine, and by lysophosphatidylcholine. It is initially enhanced but subsequently decreased at exposure to trypsin. Fraction Ic is less prone to activation by these agents. The results indicate that the present activity represents an enzyme form that differs from three previously described phosphodiesterases of human lung tissue. It is apparently related to, but also shows distinct differences from the Ca2+-dependent enzyme(s) of brain and heart tissue.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1977

Bovine myelin basic protein: immunochemical specificity examined by the macrophage migration inhibition test.

Guinea pigs were injected with saline or with one of the following antigens incorporated into Freund's complete adjuvant: Bovine myelin basic protein (MBP), lysozyme, carboxymethylated lysozyme, or a crude commercial calf thymus histone preparation. Examination of the migration of peritoneal cells from these animals in the presence (50 microgram/ml) or the absence of the antigens revealed, at most, a slight one-way form of cross-reactivity between MBP on the one hand and the histone preparation--and possibly also lysozyme--on the other. This was observed only with cells from animals injected with the two last-mentioned antigens. Cells from animals sensitized with either histone or lysozyme mixed with poly AU instead of Freund's complete adjuvant were also slightly inhibited in their migration by the bovine MBP. Cells from animals injected with complete Freund's adjuvant alone or with the purified protein derivative of tuberculin (PPD) in poly AU did not react to MBP. Thus, in contrast to the high degree of internal cross-reactivity shown previously MBP shows a low degree of cross-reactivity with either ordered or unordered forms of some unrelated basic proteins.

Animals↗
PubMed1976

Partial purification and characterization of adenosine- and guanosine-3',5'-monophosphate phosphodiesterases from human lung tissue.

Crude extracts of human lung tissue were examined for cyclic adenosine- and guanosine-3',5'-monophosphate (cAMP and cGMP) phosphodiesterase activities. Nonlinear reciprocal plots were observed for each substrate. DEAE-Sephadex chromatography of the extracts revealed four main fractions of activity, which were further purified by Sephadex gel filtration. The phosphodiesterase activity of the resulting individual fractions was partially characterized with respect to substrate specificity, kinetic parameters, apparent molecular weight (gel filtration), thermal stability at 30 and 37 degrees C, effect of the cyclic nucleotide not utilized as substrate, and the possible influence of Ca2+-dependent protein activator. The results indicate that the tissue contains phosphodiesterases with strict specificity and a high apparent affinity for each of the two cyclic nucleotides (the Km values determined were approximately 0.3-0.4 muM). The high affinity cAMP phosphodiesterase activity was enriched in two of the purified fractions; both activities probably represent fragments of the native high affinity cAMP specific enzyme. A third purified phosphodiesterase showed mixed substrate specificity. The Km value recorded for hydrolysis of either substrate with this enzyme was approximately 25 muM. A fourth, irregularly occurring, phosphodiesterase activity also showed mixed substrate specificity. The Km value registered for hydrolysis of either substrate with this fraction was approximately 0.4 muM. There was no evidence for a Ca2+-dependent specific activation by a boiled lung tissue supernatant of any of the purified enzymes.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1976

Encephalitogenic activity of the N-terminal part of bovine myelin basic protein in rabbits.

The disease-inducing activity of the N-terminal part (residues 1-42) of bovine myelin basic protein in rabbits is localized to two regions. One encephalitogenic determined probably incorporates at least one of the lysine residues (Nos. 4 and 11); the other is within residues 20-36. It is concluded that region 1-42 shows a comparably strong degree of encephalitogenicity for rabbits.

Animals↗
PubMed1976

Blocking the encephalitogenic activity of the C-terminal part of the basic myelin protein in rabbits by treatment with serum.

Peptides HNB-92-169 and 116-169, tyr, derivatives of the C-terminal part of bovine myelin basic protein, sensitize rabbits for experimental allergic encephalomyelitis (EAE). Dissolving these peptides in heat-inactivated normal guinea-pig, human, or monkey serum immediately before emulsification with Freund's complete adjuvant (FCA) abrogated their disease-inducing activity. Dissolving them in homologous or autologous serum only slightly affected the encephalitogenicity.

Animals↗
PubMed1975

Leukocyte migration in agarose, a study on multiple sclerosis.

The effect of low concentrations of bovine encephalitogenic protein on the migration of human peripheral leukocytes in agarose was studied. A concentration of 0.3 mug/ml of the protein stimulated the migration of cells from many donors, including some healthy subjects. An indirect technique suggested that the migration enhancement is due to the production of soluble factor, possibly corresponding to the leukocyte migration enhancement factor described by others. The frequency of subjects whose cells could be stimulated and the recorded degree of stimulation tended to be higher in a group of patients with multiple sclerosis than in a group of healthy subjects. When the effect of some of the main peptide fragments of the protein was studied on cells that were stimulated by the intact protein, one or more of these peptides sometimes induced the opposite effect: a migration inhibition. There is, apparently, a complex balance between enhancing and inhibiting factors acting on leukocyte migration in vitro; and the character of the antigen seems to be one important factor.

Amyotrophic Lateral Sclerosis↗
PubMed1975

Effect of encephalitogenic protein on the migration in agarose of leucocytes from patients with multiple sclerosis. Correlations with clinical parameters, localization of antigenic determinants, and influence of corticotrophin treatment.

We have extended the results from our previous investigation of the reactivity of leucocytes from patients with multiple sclerosis and some other neurological diseases to bovine encephalitogenic protein, using the migration in agarose technique. 1. Reactivity (i.e. behaviour in the test deviating from that expected with cells from healthy subjects) is manifested either as an enhancement or an inhibition of leucocyte migration. 2. The incidence of subjects with cells showing reactivity to encephalitogenic protein is higher in the group of patients with multiple sclerosis than in the group of patients with other neurological diseases. 3. Reactivity to encephalitogenic protein is correlated to disease course score; patients with a chronic progression of the disease show the strongest reactivity in the test. 4. The tryptophan-containing region of the encephalitogenic protein appears to be a major determinant of significance for this test. 5. Patients tested during corticotrophin treatment tend to show a higher degree of reactivity in the test than expected-the increased reactivity seems to be primarily directed to the tryptophan-containing region.

Adrenocorticotropic Hormone↗
PubMed1975

Disease-inducing activity of different parts of bovine encephalitogenic protein in guinea-pigs.

The encephalitogenic activity of different parts of bovine encephalitogenic protein (BEP) has been tested in guinea-pigs, mainly at a dose equimolar to 32 mug of intact protein. A high activity was found with complete protein and with region 89-169; both peptide 43-115, tyr (modified at the tyrosine residue 67) and HNB-89-169 (modified at the tryptophan residue 115) showed a moderate but clear-cut activity, whereas that of peptide 1-42 was very faint. No qualitative differences in the disease induced by the different peptides could be found; in only one animal out of 139 were clinical signs observed without evidence of histological disease. Slight histological changes, similar to those seen at EAE, were found in four out of 19 animals injected with Freund's complete adjuvant only.

Animals↗