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Biomedical subjects

R Geiger

Publications and source records attributed to R Geiger.

At least 109 records · Page 6Linked to original sources
PubMed1980

Biochemistry and functional aspects of human glandular kallikreins.

Human urinary kallikrein was purified by gel filtration on Sephacryl S-200 and affinity chromatography on aprotinin-Sepharose, followed by ion exchange chromatography on DEAE-Sepharose. In dodecylsulfate gel electrophoresis two protein bands with molecular weights of 41,000 and 34,000 were separated. The amino acid composition and the carbohydrate content of the kallikrein preparation were determined; isoleucine was identified as the only aminoterminal amino acid. The bimolecular velocity constant for the inhibition by diisopropyl fluorophosphate was determined as 9 +/- 2 1 mol-1 min-1. The hydrolysis of a number of substrates was investigated and AcPheArgOEt was found to be the most sensitive substrate for human urinary kallikrein. Using this substrate an assay method for kallikrein in human urine was developed. It was shown by radioimmunoassay that pig pancreatic kallikrein can be absorbed in the rat intestinal tract. Furthermore, in dogs the renal excretion of glandular kallikrein from blood was demonstrated by radioimmunological methods.

Amino Acids↗
PubMed1980

Determination of kallikrein by radioimmunoassay in human body fluids.

A sensitive and specific radioimmunoassay for human urinary kallikrein was developed, which allows tissue kallikrein determination in human urine, saliva, pancreatic juice, bile and sweat. In several body fluids a kallikrein-like antigen was found, but not in gastric juice and breast milk. According to gel filtration studies, complex formation of kallikrein with serum proteins or different molecular weight forms of kallikrein in serum and urine may be assumed. Pancreatic kallikrein secretion follows the same pattern after stimulation with secretin and cholecystokinin as trypsin and chymotrypsin in normal individuals. In chronic pancreatitis the kinetic behaviour remains unchanged with respect to the enzyme secretion, but the secretion of kallikrein is reduced to about 20%.

Body Fluids↗
PubMed1980

Kininogenase activity in plasma membranes and cell organelles from rabbit kidney cortex: subcellular localization of renal kallikrein by free-flow electrophoresis and density-gradient fractionation.

Subcellular fractions were prepared from a rabbit kidney cortex homogenate by density gradient and free-flow electrophoresis techniques. After enzymatic and morphologic characterization, we determined the kininogenase activity in the different fractions. This activity was present in those plasma membranes that also contained high specific activities Na-K-ATPase and in lysosomal-like particles. No activity was found in the lumen, that is, the microvillous part of the proximal tubule cell. The kallikrein-like nature of this kininogenase activity was established by several methods.

Animals↗
PubMed1980

Isolation and characterization of human urinary kallikrein.

Human urinary kallikrein was purified by gel filtration on Sephacryl S-200 and affinity chromatography on aprotinin-Sepharose, followed by ion exchange chromatography on DEAE-Sepharose. Thus an enzyme preparation with a specific activity (using AcPheArgOEt as substrate) of 1 100 U/mg protein was obtained. A specific bioligical activity of 2 300 KE/mg was measured in the dog blood pressure assay and of 0.742 HMW kininogen-U/mg, corresponding to the liberation of 787 micrograms bradykinin per mg enzyme per min from HMW-kininogen, in the rat uterus assay. In dodecyl sulfate electrophoresis two protein bands with apparent molecular weights of 41 000 and 34 000 were separated. The amino acid composition was determined and isoleucine was identified as the only aminoterminal amino acid. On isoelectric focusing six protein bands with isoelectric points of 3.75, 3.80, 3.90, 4.00, 4.05 and 4.25 were separated. The kinetic constants for the kallikrein-catalyzed hyrdolysis of AcPheArgOEt and D ValLeuArgNHNp were determined. The bimolecular velocity constant for the inhibition by diisopropyl fluorophosphate was determined as 9 +/- 2l x mol-1 x min-1. Immunological studies showed that a close relationship exists between the urinary enzyme and other human glandular kallikreins. Deoxycholate, lysolecithin and other amphiphiles activated human urinary kallikrein.

Amino Acids↗
PubMed1980

Isolation of an enzymatically active glandular kallikrein from human plasma by immunoaffinity chromatography.

A glandular kallikrein from human plasma was isolated by immunoaffinity chromatography and characterized. The molecular weight was determined to 40,000 by gel filtration. The enzyme preparation liberates kinins from human HMW kininogen (specific activity: 0.328 HMW kininogen-U/A280 unit), lowers the blood pressure of dogs after intravenous injection (specific activity: 1090 KE/A280 unit), is inhibited by diisopropyl fluorophosphate and aprotinin, but not by SBTI. In the radioimmunoassay for human urinary kallikrein parallel binding curves were obtained. AcPheArgOEt, DVal-LeuArgOEt and ZTyrONp are cleaved with identical rates by the kallikrein preparation and human urinary kallikrein.

Chromatography, Affinity↗
PubMed1980

Radioimmunoassay of human urinary kallikrein: determination of human urinary kallikrein, II.

A radioimmunoassay for the determination of human urinary kallikrein was developed. The sensitivity of the assay was 0.5 microgram/l. Dose-response curves of human submandibular and parotid saliva, sweat, pancreatic juice and bile paralleled the standard curve obtained with purified human urinary kallikrein. Substances with similar antigenic determinants were also found in human serum, ascites, seminal plasma, amniotic fluid, cervical mucus, tears, liquor and faeces, but not in human breast milk and gastric juice. Moreover, immunoreactive material was detected in the urine of guinea pigs, orangoutangs and chimpanzees, but not in the urine of rats, cats and rabbits. Porcine acrosin and kallikrein, as well as bovine trypsin and chymotrypsin, showed no cross reactivity.

Cross Reactions↗
PubMed1980

Urinary kallikrein in normotensive subjects and in patients with essential hypertension.

Basal 24 hour urinary kallikrein excretion of 20 patients with uncomplicated essential hypertension did not differ significantly from that of 18 normotensive age-matched control subjects. 4 of the 20 hypertensive patients, however, had low kallikrein excretion. Furosemide (40 mg i.v.) caused an increase of urinary kallikrein excretion in the normotensive subjects and in most of the patients with essential hypertension. The stimulating effect of furosemide was less pronounced or even absent in 7 hypertensives. No circadian rhythm of urinary kallikrein excretion was observed. There were weak correlations between 24 hour kallikrein excretion and urinary volume (r=0.59; p < 0.05), and potassium excretion (r=0.51; p < 0.05) in the normotensives. In the hypertensives correlations were found between 24 hour kallikrein excretion and potassium excretion (r=0.51; p < 0.05), aldosterone excretion (r=0.57; p < 0.01), and creatinine clearance (r=0.59; p < 0.01). Our findings do not support the concept that the renal kallikrein-kinin system might play a primary role in the pathogenesis of essential hypertension.

Adult↗
PubMed1980

Relationship between binding affinities to cellular retinoic acid-binding protein and in vivo and in vitro properties for 18 retinoids.

A new rapid assay has been developed for measurement of the binding of [3H]retinoic acid to cellular retinoic acid-binding protein. The assay, which uses activated charcoal for the separation of bound from unbound retinoic acid, was used to determine the concentration required to inhibit the binding of [3H]retinoic acid to cellular retinoic acid-binding protein by 50% for 18 retinoids with free carboxylic acid groups. Partially purified cellular retinoic acid-binding proteins isolated from rat testes and carcinogen-induced rat mammary tumors were used for these determinations. The following parameters were also determined for some or all of the retinoids: hypervitaminosis A doses; activity against carcinogen-induced mouse skin papillomas; inhibition of growth of a rat chondrosarcoma; inhibition of growth of 3T6 cells; and differentiation of the embryonal carcinoma cell line PCC4.azaIR. While all retinoids that are potent in these biological test systems bind tightly to cellular retinoic acid-binding protein, the converse is not true. The lack of a consistent quantitative correlation between 50% inhibitory concentration and biological activity is probably due to insufficient concentrations of the retinoid in the target tissue or celll, which is a consequence of factors such as absorbability, metabolism, tissue distribution, and pharmacokinetics.

Animals↗
PubMed1979

Urinary kallikrein in normotensive subjects and in patients with essential hypertension.

1. Excretion of urinary kallikrein was normal in 13 out of 15 patients with uncomplicated essential hypertension. 2. Frusemide increased urinary kallikrein excretion in normotensive subjects and in patients with essential hypertension. The stimulating effect of frusemide on urinary kallikrein was significantly diminished in patients with essential hypertension. 3. No correlations of urinary kallikrein with sodium, potassium, and aldosterone excretion were found. 4. The results do not support the idea that urinary kallikrein plays a primary role in the pathogenesis of essential hypertension.

Adult↗
PubMed1979

Inhibition of porcine glandular kallikreins by structurally homologous proteinase inhibitors of the Kunitz (Trasylol) type. Significance of the basic nature of amino acid residues in subside positions for kallikrein inhibition.

The newly synthesized chromogenic substrate D ValLeuArgNHNp was employed to study the inhibition strength of Trasylol-like inhibitors from bovine lung (TKI), sea anemone (SAI), snake venoms (NNV and HHV), snails (HPI) and cow colostrum (CTI) against porcine pancreatic, submandibular and urinary kallikreins. The dissociation constants of the corresponding kallikrein-inhibitor complexes were found close to Ki = 1.5 x 10(-9)M (TKI, SAI, NNV) or to Ki = 10--210 x 10(-9)M (HHV, HPI). CTI does not inhibit the three porcine glandular kallikreins. Comparison of the inhibitory active areas of the inhibitors with their affinities to the three kallikreins shows that kallikrein inhibition is observed only if basic amino acid residues are present in distinct positions of the inhibitory active sites.

Amino Acid Sequence↗
PubMed1979

Similarity between a kininogenase (kallikrein) from human large intestine and human urinary kallikrein.

A human colon kininogenase (kallikrein) was isolated by gel filtration on Sephacryl S-200 and affinity chromatography on Trasylolbound Sepharose, yielding a material with a specific activity of 1.3 U/mg (substrate: AcPheArgOEt). The molecular weight of the enzyme as estimated by gel filtration is approximately 70 000. After reduction with mercaptoethanol two bands were obtained in dodecyl sulfate eletrophoresis with molecular weights of 27 000 and 70 000. The bimolecular velocity constant for the inhibition by diisopropyl fluorophosphate was determined as 4 l x mol-1 x min-1. The preparation was characterized by immunological and enzymatic methods. Using the radioimmumoassay for human urinary kallikrein cross-reactivity and parallel binding curves were obtained. Kinin liberation from human high Mr-kininogen was totally inhibited by antibodies directed against human urinary kallikrein. Trasylol and diisopropyl fluorophosphate, but not by antibodies directed against human trypsin and plasma kallikrein. The effect on dog blood pressure was comparable to that obtained with human urinary kallikrein. The amino acid composition of human large intestine kallikrein is very similar to that of human urinary kallikrein.

Animals↗