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Biomedical subjects

M Nagelschmidt

Publications and source records attributed to M Nagelschmidt.

At least 55 records · Page 3Linked to original sources
PubMed1987

Effect of fibronectin therapy and fibronectin deficiency on wound healing: a study in rats.

Rats with standardized 3rd-degree burns of 1% body surface were treated intraperitoneally with different doses of human fibronectin or swine gelatin immediately after injury and on the following days. Controls received bovine albumin or no further treatment. Wound healing was assessed by planimetry (days 0, 2, and 7); additionally, plasma fibronectin was determined (days 3 and 7). On day 3 fibronectin levels were significantly elevated after albumin and the highest dosage of fibronectin (3 X 16 mg) and decreased after gelatin and the lowest dosage of fibronectin (3 X 4 mg). Wound healing was neither affected by albumin nor by human fibronectin, but it was significantly impaired by gelatin-induced lack of fibronectin. The data support the opinion that fibronectin is an essential factor for the post-traumatic clearance of gelatin-like tissue debris via the reticuloendothelial system (RES). Overload by gelatin results in fibronectin deficiency and RES dysfunction with risks of infection and poor wound healing.

Animals↗
PubMed1987

Proteolytic enzymes as new tumor markers in rats with benzopyrene sarcoma.

Proteolytic enzymes may facilitate tumor invasion by histolysis of the surrounding tissue and inhibit tumor growth in the course of host defense reactions. Using chromogenic peptide substrates, we looked for proteolytic activities related to carcinogenesis in serum and tumor extracts of rats with benzopyrene sarcomas. The enzymatic hydrolysis of two substrates (Boc-(Ala)2-p-nitroanilide and Bz-Lys-p-nitroanilide) was significantly decreased in the sera of tumor-bearing animals (P less than 0.01). This loss of proteolytic activity was highly correlated to tumor growth, so these enzymes might become useful as new tumor markers. In the tumor extracts, we found the Boc-(Ala)2-p-nitroanilide cleaving activity increased with tumor weight, whereas the Bz-Lys-p-nitroanilide cleaving activity did not exhibit any correlation to tumor growth. Studies on the potential use of these results for cancer patients are indicated.

Aminopeptidases↗
PubMed1987

Proteolytic enzymes as new tumor markers in chemical carcinogenesis of intestinal tumors.

Because the role of proteolytic enzymes in carcinogenesis is not yet well understood, we studied two arylamidases cleaving Boc-(Ala)2-p-nitroanilide and Bz-Lys-p-nitroanilide in the sera of rats during azoxymethane (AOM)-induced development of bowel carcinomas. Both proteolytic activities exhibited similar patterns: During administration of the carcinogen they increased up to 2.1-fold (Boc-[Ala]2-Nan) and 1.7-fold (Bz-Lys-Nan) the activity of the control group (P less than 0.05). Subsequently they decreased, passing the normal range between weeks 16 and 20 after the first AOM treatment and then diminishing continuously with increasing manifestation of tumors. At week 24 when the last animals were sacrificed enzyme activities were only 36.5% and 43.7% of the controls (P less than 0.05). The early increase may be related to direct effects of the carcinogen. The decrease of serum activity in the further course, however, seems to be a typical event of invasive tumor growth, because a similar loss of activity was also observed in rats with benzopyrene sarcomas. We conclude that both arylamidases may become useful as nonspecific tumor markers.

Aminopeptidases↗
PubMed1983

[Age-related problems of wound healing].

A study on wound failures after surgical operations performed at the Dep. of Surgery, Köln-Merheim, revealed an overall rate of 10,8%. 40,3% of all complications were observed in patients aged more than 60 years, which gives a rate of 19,1% for those people. To date this significant increase of wound failures in older individuals is preferently explained by the reduced resistance of the old organism to infections. Our trials with rats as well as numerous publications of other authors on the topic of age-related changes of metabolism prove that the wound healing process is delayed in older individuals. This fact does not consequently lead to complications but the prolonged healing in connection with the repeated change of wound dressing gives an enhanced risk for infections. If special precautions are observed the age of a patient is not a principal contraindication to a great surgical operation today.

Adolescent↗
PubMed1982

Amino acid-p-nitroanilide and -beta-naphthylamide cleaving activities in rat serum.

Determination of proteolytic activities gains increasing importance for the diagnosis of various pathologic conditions. Many questions can only be solved with the aid of experiments with animals. In preparation of such studies the pattern of the enzymatic hydrolysis of 20 amino acid-p-nitroanilides and one -beta-naphthylamide by normal rat serum was measured. The pH dependences of the single reactions are reported as well as their sensitivity to the action of ethylenediaminetetraacetic acid, dithioerithrol, and puromycin. Additionally, it is shown that collecting of the blood by cardiac puncture and preparation of the native plasma is the best way to get reproducible results.

Amino Acids↗
PubMed1979

Purification and properties of a collagen peptidase (PZ-peptidase) from rabbit serum.

A peptidase cleaving a synthetic substrate for collagen peptidases, 4-phenylazobenzyloxcarbonyl-L-Pro-L-Leu-Gly-L-pro-D-Arg (designated as PZ-peptide) has been purified 1200-fold from rabbit serum and characterized. The enzyme preparation is free of collagenase and unspecific proteinase activity. The natural substrates are denatured collagen and collagen peptides. The peptidase has a molecular weight of 124 000 and an isoelectric point at pH 5.1. The pH dependence curve exhibits two maxima, one at pH 7.1 and the other at pH 7.9. The enzymic reaction is completely inhibited by Zn2+ and to a slower degree by Hg2+, Mn2+ and p-hydroxymercuribenzoate. It is not affected by EDTA and KCN but totally blocked by o-phenanthroline. Phenylmethylsulfonylfluoride is completely inhibitory and points to a serine residue in the active site.

Animals↗
PubMed1979

[Inhibition of PZ-peptidases by serum (author's transl)].

The inhibition of two PZ-peptidases by several sera was studied with the aid of methods based on the PZ-peptidase assay of Wünsch and Heidrich Clostridiopeptidase A is inhibited by all sera, whilst the PZ-peptidase from the rabbit serum is inhibited only by heterologous sera. The inhibition is weak and cannot be compared with the strong serum inhibition shown by collagenases.

Animals↗
PubMed1979

Relaxin and collagen metabolism.

The influence of the peptide hormone relaxin on collagen metabolism was studied in the symphysis pubis of the mouse. In the tissue the content of water and of acid soluble collagen in relation to total collagen is increased by hormonal treatment. Total collagen calculated in relation to the dry weight is decreased. Collagenase which was also detected in the symphyses of the controls is slightly enhanced. In serum collagen peptidase and collagen peptidase inhibitor as well as cyclic AMP exhibit distinctly increased levels. The effects can be suppressed by administration of relaxin-specific antisera. The data make clear that in the symphysis relaxin activates the collagenolytic system.

Animals↗
PubMed1979

N-Acetylaminoacyl-p-nitranilidase from human placenta. Purification and some properties.

An enzyme hydrolyzing N-acetylaminoacyl-p-nitroanilides has been isolated from mature human placentae by a six-step procedure comprising extraction from a placenta homogenate, ammonium sulfate fractionation, treatment with isopentyl alcohol, chromatography on CM-Sephadex, protamine sulfate precipitation and gel filtration on an Ultrogel AcA 34 column. About 2500-fold enrichement was achieved from placenta homogenate. The purified enzyme preparation showed a single band on polyacrylamide disc electrophoresis. The molecular weight was estimated to be 380,000 by gel filtration. Placental extracts contain two main isoenzymes of pI 3.9 and 4.5 respectively. Activity was strongly inhibited by chloromercuribenzoate, slightly inhibited by Ca2+ and cysteine; no activation could be detected. The enzyme exhibits an exopeptidase-like activity towards acetyl-dipeptides with a certain specifity towards N-acetylalanyl-alanine; N-acetylalanine-p-nitroanilide, however, is hydrolyzed four times faster. With N-acetylalanine-p-nitroanilide as substrate the pH optimum was 8.0--8.2; Km was 2.13 mmol/l. N-Acetylleucine-p-nitroanilide and N-acetyltyrosine-p-nitroanilide were split slowly; N-acetylalanyl-alanyl-alanine-p-nitroanilide, N-butyloxycarbonyl-alanyl-alanine-p-nitroanilide, unsubstituted analogous aminoacyl-p-nitroanilides and several protein substrates were not hydrolyzed. The functions of the enzyme are still unknown.

Aminopeptidases↗
PubMed1978

[Effect of exogenous collagen on the metabolism of rat burns].

Standardized burns on rats were treated with 14C-labeled collagen from guinea pig skin. Collagen fractions of different solubility were extracted from the wounds during healing and the incorporation rates were measured. In the neutral salt-soluble fraction, maximal specific activity was found on day 7 after application of the burns; 1,65% of the applied label was incoporated, and it was calculated that 11,8% of the total neutral salt-soluble collagen of the wounds originated from the applied exogenous collagen. In the citric acid soluble collagen, maximal specific activity was observed on day 9; 1,48% of the applied label was incorporated; 6,0% of total citric acid-soluble collagen of the wounds was derived from the exogenous collagen. In the insoluble collagen, no significant increase in radioactivity was observed before day 14 after burning. The results support the opinion that exogenous collagen is used for substitution in connection with endogenous collagen synthesis.

Animals↗
PubMed1977

[Relaxin and cervical dilatation during parturition (author's transl)].

Relaxin concentrations during pregnancy and parturition were measured in tissue specimens of the uterine cervix of 27 women in childbearing age. During pregnancy relaxin levels increase from 0.4 guinea pig unit (GPU) to 0.94 GPU/mg soluble tissue protein. Already during parturition (0.41 GPU) and immediately post partum (0.39 GPU) the hormone concentrations have dropped back to normal. It appears that the biochemical changes which occur in the connective tissue of the uterine cervix during pregnancy and parturition are influenced by relaxin. Experimental animals were taken to show if relaxin acts by activation of collagenolytic enzymes. In the mouse a rise in the activity of collagen-peptidase and of the inhibitor of collagen-peptidase in plasma was found after subcutaneous injections of relaxin. The addition of human cervical tissue extracts resulted in an increase of enzyme-activation (even higher than could be expected of the hormone concentrations of the individual extracts). The highest levels of the enzyme were found after injections of extracts from cervical tissue specimens of parturient women.

Animals↗
PubMed1977

[Pz peptidase activity in serum (author's transl)].

Synthetic PZ peptide, synthesized by Wünsch and Heidrich, was used as substrate to determine PZ peptidase activities in the sera of man, rabbit, guinea pig and mouse. The PZ peptidase from rabbit serum was purified 200 fold and characterized. The enzyme has an isoelectric point of 5.0 and pH optima at pH 7.2 and pH 7.9. Its behaviour on gel filtration points to a molecular weight of 60.000 dalton. The peptidase is inhibited by heavy metal ions, SH reagents and serum. Ca ions are EDTA are without any effect. In contrast to collagen peptidases from micro-organisms, the enzyme from rabbit serum does not attack native, but only denatured collagen. The results suggest that PZ peptidases participate in collagen breakdown by cleaving the collagen fragments which are released by the collagenases.

Adult↗
PubMed1977

Hydroxyproline fractions in serum and urine of rats during wound healing.

Total hydroxyproline in urine and free hydroxyproline, free and peptide hydroxyproline and protein bound hydroxyproline in serum are measured during wound healing in rats. The free and free+peptide fractions vary in concert with each other and with urine hydroxyproline. Protein bound hydroxyproline fractions take a very different course and behave as an acute phase reactant. The results suggest that protein bound hydroxyproline does not mirror collagen turnover but may be more relevant to C1q or complement metabolism.

Animals↗
PubMed1977

[Influence of exogenous collagen on the metabolism of skin wounds in rats].

Skin wounds of rats were treated by 14C-labeled collagen from guinea pig skin. The main portion of the applied collagen persisted in the wound area. In the neutral salt soluble collagen maximal specific activity was measured on day 4 after treatment, in the citric acid soluble and in the insoluble collagen at later times. On day 4 after treatment 3.42% of the applied label was found in the neutral salt soluble, 1.43% in the citric acid soluble and 1.40% in the insoluble collagen. The findings suggest that the stimulation of wound healing which is reported by various authors is caused by the incorporation of the applied collagen into the regenerating connective tissue.

Animals↗
PubMed1977

[Hydroxyproline fractions in blood (author's transl)].

Modified methods for the determination of bound hydroxyproline in blood are presented. The fractionated and hydrolyzed samples are separated from interfering material by ion exchange chromatography. Internal standards are used to correct for recovery. After a several fold concentration of samples it is possible to work with reduced blood volumes. Up to 6.12 mumol/l of free and peptide-bound and 11.5 mumol/l of protein-bound hydroxyproline are detectable. Using the described methods hydroxyproline was determined in a pooled human plasma and in the sera of rats.

Animals↗