Search PubMed⌕ Search

Biomedical subjects

K Maier

Publications and source records attributed to K Maier.

87 records · Page 5Linked to original sources
PubMed1982

Blood levels of a pteridine-binding alpha 1-acid glycoprotein in cancer patients.

A variant of alpha 1-acid glycoprotein was found previously in blood of malignant cases. It had been characterized as a pteridine-binding alpha 1-acid glycoprotein (P-AGPM). P-AGPM as well as the corresponding fraction of control origin were selectively enriched in the supernatant (Fraction b), obtained after digitonin extraction and subsequent alcohol and trichloroacetic acid fractionation of whole blood. In Fraction b, alpha 1-acid glycoprotein from control subjects + P-AGPM comprised 90 to 95% of total protein; it was quantitated by colorimetric determination of the protein-bound tyrosine and calibrated with the isolated compound. During a screening of malignant and nonmalignant cases, P-AGPM proved to be an acute-phase reactant to some extent. Marked increases during extended cancer and especially during leukemias corroborated the view that P-AGPM may be identical with abnormal orosomucoid. Longitudinal sections during leukemias suggested that the biopterin of leukemic cells may be metabolically related to the pteridine moiety of P-AGPM. Biopterin determinations by means of Crithidia assay in the blood of 136 cases of solid tumors showed that, due to its high rate of renal clearance, blood biopterin is not a reliable and persistent marker for proliferative activity, unless it is contained in the immature blood cells themselves, as is the case during leukemias.

Biopterins↗
PubMed1981

The substrate specificity of proteinase B from baker's yeast.

The substrate specificity of proteinase B (EC 3.4.22.9) from Baker's yeast was studied. Experiments with unblocked synthetic peptides indicated that the enzyme has no aminopeptidase activity. The proteinase cleaves trypsin substrates like Bz-Arg-OEt, Bz-Arg-pNA and Bz-Ile-Glu-Gly-Arg-pNA and chymotrypsin substrates like Ac-Tyr-OEt and Bz-Tyr-pNA. The Km value for Ac-Tyr-OEt is similar to that of chymotrypsin A, but the catalytic activity per mol proteinase B amounts to only 1/20 that of chymotrypsin A. Km and kcat for Bz-Arg-OEt are 1/50 and 1/7 as high as the corresponding values determined for trypsin. Proteinase B cleaved the oxidized insulin B chain with an initial rapid cleavage step at Leu(15)-Tyr(16) and Phe(24)-Phe(25). Slower hydrolysis was observed at Gln(4)-His(5), Leu(11)-Val(12) Tyr(16)-Leu(17), Leu(17)-Val(18), Arg(22)-Gly(23) and Phe(25)-Tyr(26). These results suggest that the specificity of proteinase B is comparable to the specificity of porcine chymotrypsin C as well as of trypsin. When the hexapeptide Leu-Trp-Met-Arg-Phe-Ala was used as a substrate for proteinase B, the enzyme preferentially attacked at Arg-Phe and more slowly at Trp-Met.

Binding Sites↗
PubMed1981

[Multicentric early cancer of the stomach (author's transl)].

In more than 16000 gastroscopies we found 65 (0.4%) cases of early cancer (e.c.), that is an amount of 12.3% of the total diagnosed cancers of the stomach. In 8 patients we found two or three sites of involvement in the stomach (12.3%). The control reading of 53 gastrocamerafilms with e.c. shows, that 20% of suspicious areas have been missed by using the routine interpretation and gastroscopy. It is proposed, that before each stomach surgery for e.c., the upper gastric region be investigated carefully for missed second lesions. This is rather difficult with prograde optic gastroscops. The instrument of choice for that purpose is the gastrocamera.

Adult↗
PubMed1980

Therapeutic efficacy of sulfasalazine and its metabolites in patients with ulcerative colitis and Crohn's disease.

We studied the therapeutic efficacy of sulfasalazine and its metabolites sulfapyridine and 5-aminosalicylic acid in nine patients with Crohn's disease and in 23 patients with ulcerative colitis. In a randomized, controlled trial, we treated 11 patients for six weeks with 1 g of sulfasalazine three times a day, seven patients with 0.5 g of sulfapyridine three times a day, and 14 patients with 0.5 g of 5-aminosalicylic acid suppositories three times a day. The clinical state of the disease was characterized by an activity index, quality of stool, and remission rate. In addition, we monitored plasma levels of sulfapyridine, 5-aminosalicylic acid, and their acetylated metabolites. The initial activity index (mean +/- S.D.) was significantly reduced by sulfasalazine (from 245 +/- 129 to 100 +/- 71; P < 0.001) and by 5-aminosalicylic acid (from 251 +/- 65 to 90 +/- 93; P < 0.0001), but sulfapyridine was without benefit. Stool quality was also improved by sulfasalazine (82 per cent of the cases) and by 5-aminosalicylic acid (79 per cent). The highest remission rate was achieved with 5-aminosalicylic acid (86 per cent), followed by sulfasalazine (64 per cent) and sulfapyridine (14 per cent). Our investigations show that 5-aminosalicylic acid is the active moiety of sulfasalazine and that this effective metabolite may be an alternative to sulfasalazine in inflammatory bowel disease.

Adult↗
PubMed1979

Primary structure of yeast proteinase B inhibitor 2.

The complete amino acid sequence of yeast proteinase B inhibitor 2 (IB2) was determined to be H3N+-Thr-Lys-Asn-Phe-Ile-Val-Thr-Leu-Lys-Lys-Asn-Thr-Pro-Asp-Val-Glu-Ala-Lys-Lys-Phe-Leu-Asp-Ser-Val-His-His-Ala-Gly-Gly-Ser-Ile-Leu-His-Glu-Phe-Asp-Ile-Ile-Lys-Gly-Tyr-Thr-Ile-Lys-Val-Pro-Asp-Val-Leu-His-Leu-Asn-Lys-Leu-Lys-Glu-Lys-His-Asn-Asp-Val-Ile-Glu-Asn-Val-Glu-Asp-Lys-Glu-Val-His-Thr-Asn-COO-. Elucidation of the primary structure was enabled by automated Edman degradation and COOH-terminal hydrolysis with carboxypeptidases A (bovine pancreas and Y (yeast). IB2 is the first proteinase inhibitor to be sequenced that possesses a structure devoid of disulfide bridges.

Amino Acid Sequence↗
PubMed1979

Purification and molecular characterization of two inhibitors of yeast proteinase B.

A rapid purification procedure for large scale preparations of yeast proteinase B inhibitors 1 and 2 (IB1 and IB2) is described. By disc gel electrophoresis, amino acid analysis, and end-group determinations, each of the inhibitors is homogeneous. Both inhibitors are polypeptides with molecular weights of 8,500, containing 74 residues. No components other than amino acids could be detected. There is no significant difference in the amino acid compositions of the two inhibitors as analyzed after acid hydrolysis. Both polypeptides are characterized by the total absence of arginine, tryptophan, and sulfur-containing amino acid residues. The proteinase B inhibitors of yeast, therefore, differ fundamentally from proteinase inhibitors of many other organisms, which generally contain a large number of disulfide bridges. Both proteinase B inhibitors have threonine as the NH2-terminal residue and -Val-His-Thr-Asn-COO- as the COOH-terminal sequence. Comparison of peptide maps after tryptic digestion reveals that the two inhibitors differ definitely in only a few tryptic peptides. The inhibitors are rapidly inactivated by digestion with carboxypeptidase A from bovine pancreas at pH 8.5. Inactivation occurs stoichiometrically with the release of threonine, the penultimate residue at the COOH-terminal end of both inhibitors.

Amino Acids↗
PubMed1976

International standard (C.C.I.T.T.) for transmitting biomedical analogue and digital data on the public telephone network.

Analogue transmission of biomedical signals over the public telephone network has advantages from the economic point of view over digitalized transmission. This paper deals with the special problems encountered with the transmission of biomedical signals. Furthermore, the new international transmission standard C.C.I.T.T. recommendation V. 16 is introduced. This standard has recently been adopted by the relevant study group and has been presented to the Plenary Assembly of the C.C.I.T.T. for final approval. This standard is compatible with the existing public telephone networks. The technical specifications of this standard allow the transmission of the three-channel ECG for diagnostic purposes, e.g., remote processing and computer-assisted evaluation, as well as the transmission of the one-channel ECG with acoustic coupling, e.g., in emergency cases and for pace maker monitoring.

Analog-Digital Conversion↗
PubMedDate not supplied

Cell-mediated cytotoxicity in hepatitis A virus infection.

We studied cell-mediated cytotoxicity to hepatitis A virus-infected cells in seven patients with acute type A hepatitis and two controls. Skin fibroblast cultures obtained from the skin biopsies of seven patients after acute hepatitis A virus infection and from two persons without history of current or past hepatitis A virus infection were inoculated with hepatitis A virus. Infection of fibroblast cultures always resulted in an inapparent, persistent infection with production and release of infectious hepatitis A virus. Peripheral blood lymphocytes were collected from the same patients at different times after onset of icterus and were stored in liquid nitrogen. Cytolytic activity of peripheral blood lymphocytes was determined by a microcytotoxicity assay using autologous 51Cr-labeled hepatitis A virus-infected and uninfected target cells. Cytotoxic peripheral blood lymphocytes capable of lysing autologous hepatitis A virus-infected skin fibroblasts were detected in all patients with hepatitis A but were not demonstrable in the controls without antibodies against hepatitis A virus. The clinical course of the hepatitis A virus infection was normal in five patients; and in these patients, cytolytic activity of peripheral blood lymphocytes against hepatitis A virus-infected autologous targets peaked 2 to 3 weeks after onset of icterus. A clinically protracted form of the disease with persistent elevation of aminotransferases for at least 5 months after onset was present in two patients. In these cases, the highest cytolytic activity was demonstrated in peripheral blood lymphocytes collected 8 to 12 weeks after onset of icterus.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMedDate not supplied

Multilayered keratinocyte culture used for in vitro toxicology.

Human keratinocytes are the most appropriate target cells for evaluating mechanisms of skin cytotoxicity and pharmacology of chemical agents. After having formed a confluent stratified epithelium with proliferating basal cells and differentiated cell layers, human keratinocytes were harvested after enzymatic detachment as stable, three-dimensional cell aggregates or used as adherent multilayers in microtiter plates to study the local cytotoxicity of different toxic compounds. The advantage of this test is that it uses the adequate target cells and that it evaluates both the ability of the test chemical to penetrate several cellular layers as well as the ability to interfere with cellular function. The end points are cell viability and cell metabolism, which are determined by neutral red uptake and MTT reduction, respectively. For the 13 chemicals evaluated in this study we found good correlation (r = .819) between the potency rankings of keratinocyte NR 50 values and in vivo irritancy data. There was also good agreement (r = .945) between ranking of these chemicals according to midpoint toxicity of both the 3T3 assay and the keratinocyte assay. This test system might be at the present stage a supplementation of the current test battery, which shall replace in vivo irritation tests like the Draize test.

Cells, Cultured↗