Search PubMed⌕ Search

Biomedical subjects

K Bauer

Publications and source records attributed to K Bauer.

At least 253 records · Page 14Linked to original sources
PubMed1980

Catabolism of thyroliberin by rat adenohypophyseal tissue extract.

Rapid fragmentation of thyroliberin (less than Glu-His-Pro-NH2) by rat adenohypophyseal tissue enzymes could be demonstrated. Based on the identification of the metabolic products and by the demonstration that the individual enzymatic reactions can be preferentially blocked by enzyme inhibitors, specific and sensitive biochemical tests could be developed in order to monitor the enzymatic activities after gel chromatographic fractionation of the tissue extracts. These findings are in agreement with the interpretation that the observed degradation of thyroliberin by hypophyseal tissue extracts may follow the proposed pathways. The primary enzymatic cleavage of thyroliberin is either initiated by the action of a 'thyroliberin-deamidating enzyme' (thyroliberin leads to less than Glu-His-Pro-OH + NH3), or by the action of a pyroglutamate aminopeptidase (thyroliberin leads to less than Glu + His-Pro-NH2). While the pyroglutamate aminopeptidase also catalyzes the subsequent degradation of deamidated thyroliberin (less than Glu-His-Pro-OH leads to less than Glu + His-Pro-OH), the enzymatic deamidation of His-Pro-NH2 is not catalyzed by the 'thyroliberin-deamidating enzyme; but by a post-proline dipeptidyl aminopeptidase. Hydrolysis of the common intermediary metabolite His-Pro-OH to the free amino acids is apparently catalyzed by a proline dipeptidase. In addition to these enzymatic events rapid cyclization of His-Pro-NH2 to histidyl-proline-diketopiperazine His-Pro could be observed. This reaction however is mainly due to the non-enzymatic intramolecular condensation reaction which is characteristic for proline-containing dipeptide derivatives. An enzymatic activity which catalyzes this reaction could not be observed when the enzyme fractions were tested. Enzymatic degradation of His-Pro by hypophyseal tissue extracts could also not be observed.

Aminopeptidases↗
PubMed1980

[Aerosol vaccination of mice with inactivated influenza virus (author's transl)].

NMRI mice were vaccinated by the aerosol technique, using the ethylethylenimine inactivated and polyethylenglycol concentrated virus strain A/PR/8/34 (HO/N1) with or without addition of Bordetella pertussis extract (BPE) as an adjuvant. The immune response of the vaccinated animals was controlled by challenge infection via aerosol technique and by examination of HAI antibodies in the serum and in the washings of lungs. After a single aerosol vaccination a weak protection was observed only, if the vaccines contained BPE. But a second immunization with a vaccine containing BPE induced a high degree of immunity, even if a reduced amount of antigen was used for booster vaccination. After three aerosol vaccine doses in two-weeks intervals, however, we were unable to infect the immunized animals even with largest amounts of challenge virus (approximately 50 000 LD50). The addition of BPE as an adjuvant induced a significantly better protection and resulted in much higher titres of HAI antibodies in the serum and in the respiratory tract compared to mice vaccinated by the same procedure but without BPE.

Adjuvants, Immunologic↗
PubMed1980

Binding of enzyme--IgG complexes in human serum to Protein-A Sepharose CL-4B.

We describe a simple method for detecting enzyme--immunoglobulin G (IgG) complexes in human serum. Protein-A Sepharose CL-4B binds IgG and therefore also the enzyme--IgG complexes, which can then be separated easily from the serum by centrifugation. We demonstrate this separation in two patients, one with a complex of IgG and creatine kinase (EC 2.7.3.2) BB isoenzyme, the other with an IgG--alkaline phosphatase (EC 3.1.3.1) complex. Both patients had unexplainably high activities of the respective enzymes in their serum. The method we propose should be a useful, simple, routine method of detection in cases where IgG--enzyme complexes are suspected.

Aged↗
PubMed1979

Characterization of "thyroliberin-deamidating enzyme" as a post-proline-cleaving enzyme. Partial purification and enzyme-chemical analysis of the enzyme from anterior pituitary tissue.

An enzyme which catalyzes the deamidation of thyroliberin (TRF; less than Glu-His-Pro-NH2) has been purified 110-fold from extracts of bovine anterior pituitary by ammonium sulfate fractionation, ion exchange chromatography on DEAE-cellulose, and gel filtration. This enzyme of 76,000 molecular weight (as estimated by gel filtration) exhibits maximal activity at neutral pH (optimum pH 7.4 to 7.6) in buffers of high ionic strength supplemented with thiol-protecting agents. As indicated by the strong inhibition of the enzymatic activity by N-ethylmaleimide and Hg2+, as well as by the extreme sensitivity toward diisopropyl fluorophosphate, -SH, and -OH residues apparently represent essential functional groups of the enzyme. The stereospecific deamidation of TRF (Km = 4.1 . 10(-4) M) is inhibited competitively by TRF analogues which contain proline or by the proline containing biologically active peptides luliberin (LH-RF), oxytocin, vasopressin, angiotensin II, and Substance P. TRF analogues without proline or peptide amides without proline are ineffective. This enzyme cleaves the appropriate Pro-X bonds in luliberin, angiotensin II, pyroGlu-His-Pro-Gly-NH2, and the collagenase substrate Z-Gly-Pro-Leu-Gly-Pro. Thus, it may be characterized as a post-proline-cleaving enzyme.

Amidohydrolases↗
PubMed1979

[Serum ferritin and its diagnostic significance in iron metabolism disorders].

Aim of the study was the evaluation of the diagnostic value of the parameters of iron metabolism in normal adults and also in patients suffering from uncomplicated iron deficiency, iron overload due to repeated blood transfusions, malignant lymphoma and Crohn's disease. In these patients, the determination of serum ferritin increased the diagnostic efficiency only in poly-transfused patients with iron overload.

Anemia, Hypochromic↗
PubMed1979

[Endotoxin recognition with myelopoiesis of monocytes and macrophages].

Cells from the monocyte-macrophage pathway release colony-stimulating factors. The release of colony-stimulating activity is increased upon endotoxin activation in the presence of fresh serum. Heat-inactivation of serum (56 degrees C, 30 minutes) abolishes the endotoxin-mediated activation of macrophages. Decomplementation with zymosan, iodipamide and the use of commercially serum deficient in C3 provide indirect evidence for a complement dependence of the endotoxin-macrophage interaction, which leads to release of colony-stimulating activity.

Colony-Forming Units Assay↗
PubMed1979

[Comparative studies on the vaccination of mice with inactivated influenza virus administered by the aerosol technique, by the intranasal or intramuscular route (author's transl)].

NMRI mice were immunized intramuscular, intranasal or by Aerosol, using the ethylethylenimine inactivated and polyethylenglycolconcentrated influenza virus strain A/PR/8/34 (HO/N1). Differences in the immune response resulted from all three routes. Intranasal and intramuscular vaccination were superior to aerosol application. A possible explanation for this could be the fact that relatively small amounts of the inhaled virus antigen developed antigenic activity on the mucous membrane. A single vaccination by the aerosol technique gave significant protection only, if the challenge virus was applied by the same procedure. However no protection was found after intranasal challenge. Intranasal challenge on the third day post vaccination revealed that intramuscular immunization had a significant better protective effect than intranasal immunization. However from the 5th to the 10th day post vaccination this effect reversed and intranasal vaccination became superior. This immunity persisted for the whole period of observation and it was accompained by a higher titer of local antibodies. Similar results were obtained in experiments with aerosol challenge. Here only the intranasal vaccinated mice were completely protected after the 10th day post vaccinationem while intramuscular vaccinated animals were less protected. Sera of intramuscular immunized mice revealed a higher content in antibodies of the Ig M type and less of the Ig G type compared to mice vaccinated by the intranasal route.

Administration, Intranasal↗