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Biomedical subjects

M Herrmann

Publications and source records attributed to M Herrmann.

At least 217 records · Page 12Linked to original sources
PubMed1986

Determination of complement activating circulating immune complexes and an example for antigen specific immune complex assays.

For the screening of complement activating circulating immune complexes a new fluorescence linked immunosorbent assay was developed. Anti-human C3 or anti-human C4 F(ab')2 fragments were coupled to a nitrocellulose matrix. Nitrocellulose pieces of definite size covered with anti-C3 and anti-C4 were incubated with serum samples or standards for 15 min followed by a reaction with a fluorescence labelled anti-human IgG or anti-human-IgM. The nitrocellulose disks were then washed and the remaining fluorescence was read by a solid-phase fluorometer. The method was standardized by a WHO Tetanus toxoid anti-Tetanus immune complex reference substandard. (This standard and further controls were used to prove the reproducibility of the system.) Patients suffering from chronic inflammatory diseases were compared to healthy controls. The best discrimination between patients and controls was demonstrated by the determination of C3-IgG aggregates, followed by C3-IgM, C4-IgG, and C4-IgM aggregates. The easy performance, the stability of necessary chemical substances, the reliable standardization by a reference standard, and the clear-cut differences between patients and healthy control groups proved this test to be suitable for routine purposes. Furthermore, it could be demonstrated by means of an artificial model immune complex that this system can be expanded--by slight modifications--to antigen-specific CIC-assays. A CEA-anti-CEA CIC test is described as an example of an antigen specific CIC test not limited to complement activating CIC, and the data of 127 patients with colorectal carcinoma are given.

Antigen-Antibody Complex↗
PubMed1985

Tubulin domains probed by limited proteolysis and subunit-specific antibodies.

The substructure of the tubulin molecule was studied by limited proteolysis and high affinity polyclonal antibodies specific for alpha or beta-tubulin. Brief enzymatic cleavage separates the tubulin monomer into two domains of unequal size. Trypsin splits alpha-tubulin into components with Mr values of 36 X 10(3) and 14 X 10(3), chymotrypsin splits beta-tubulin into 31 X 10(3) Mr and 20 X 10(3) Mr fragments. The cleavage occurs at Arg339 (alpha) and Tyr281 (beta), as determined by sequencing several N-terminal residues of the small domains, i.e. the small domains are the C-terminal parts of the molecules, the large ones are the N-terminal parts. There is a second cleavage site of chymotrypsin within Mr 10(3) to 2 X 10(3) of the C terminus of beta-tubulin. The fragments can be separated only under denaturing conditions. They copolymerize into microtubules and incomplete microtubule walls joined by a wall junction, forming S-shapes and hooks in cross-section. The antibodies were raised against electrophoretically purified tubulin monomers. Those produced with alpha-tubulin are directed predominantly against the large domains; they are either specific for alpha-tubulin or cross-react with the large domain of beta-tubulin. Conversely, antibodies raised against beta-tubulin are directed predominantly against the small domains (beta-specific and beta-cross-reacting fractions). Thus the antibodies discriminate not only between the tubulin chains but also between the domains generated by the proteases. The complementary antigenicity correlates well with the stability of the domains. Potential sites of antigenic determinants are located within the polypeptide chains by comparing theoretical predictions with the pattern of immunoblots. Two epitopes of the alpha-cross-reacting antibodies have been located approximately. One is very close to the C terminus (within about 20 residues), the other is close to the N terminus (within about Mr 8 X 10(3) ). The epitope of the beta-cross-reacting antibody is also located within Mr 12 X 10(3) of the C terminus. The antibodies prevent microtubule assembly and cause disassembly of preformed microtubules. A variety of breakdown products are observed by electron microscopy. They include fibres of about 10 nm width, sheets with undefined substructure, thick tapered fibrous bundles and wispy filaments.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1985

Disruption of microtubules in living cells and cell models by high affinity antibodies to beta-tubulin.

Polyclonal antibodies with high affinity for beta-tubulin were found to disrupt cytoplasmic microtubules efficiently after microinjection into tissue culture cells. The degree of microtubular fragmentation was directly proportional to the amount of the injected antibody. At molar ratios of 1 antibody per 100 tubulin dimers, most microtubules were disrupted within 90 min after injection. In contrast, the time course of disintegration was relatively independent of the antibody concentration. Within the range of 1 antibody per 10(2)-10(4) tubulin dimers, the maximal values for microtubular disintegration were reached approximately 1-1.5 h after injection. Mitotic microtubules were found to be resistant to all antibody concentrations used. In living cells, microtubules recovered within a few hours after antibody-induced decay. The time course of recovery, like the extent of disintegration, was a function of the antibody concentration. The antibody acted also on microtubules in detergent-extracted cell models and on microtubules polymerised in vitro. When added to microtubular protein, the bivalent antibody as well as its Fab fragments prevented polymerisation. The data suggest that these antibodies disrupt microtubules because their affinity to tubulin is at least 100 times higher than the affinities found for tubulin:tubulin interaction. Fragmented microtubules are probably unstable and decompose into smaller units.

Animals↗
PubMed1985

Synthesis, toxicity, and therapeutic efficacy of 4-amino-N-(2'-aminophenyl)-benzamide: a new compound preferentially active in slowly growing tumors.

The present paper describes 4-amino-N-(2'-aminophenyl)benzamide (GOE1734) with regard to synthesis; toxicity in mice, rats, and dogs; and differential therapeutic efficacy in slowly and rapidly proliferating rat tumors. GOE1734, an analog of a group of compounds known for other than antitumor effects with relatively simple N-acyl-O-phenylenediamine structure, is characterized by a low bacterial mutagenic potential after in vitro metabolic activation and DNA-DNA crosslinking activity after in vivo treatment. Maximum tolerated doses in rats and dogs amount to 4 and 1 mg/kg, respectively. High growth-inhibiting efficacy was obtained in intratibially implanted osteosarcoma, in methylnitrosourea-induced primary mammary carcinoma, and in acetoxymethyl-methylnitrosamine-induced colorectal adenocarcinoma. GOE1734 proved to be ineffective in transplanted Yoshida sarcoma and Walker 256 carcinosarcoma when single or multiple doses were administered at dose levels that were moderately toxic or not toxic. Some antitumor effects were observed in L5222 leukemia after ip transplantation, but no effect could be observed after ic implantation or in vitro incubation and subsequent retransplantation of these cells. Since the latter three rat tumors are characterized by relatively short tumor volume doubling times (0.5-2 days), whereas the first three grow slower (tumor volume doubling time, 11-19 days), the remarkable differential antitumor activity of GOE1734 in fast and slowly growing malignancies is striking.

Animals↗
PubMed1984

[Metabolic parameters of CAPD and CCPD in diabetics with terminal renal insufficiency].

The effects of continuous ambulant (CAPD) and continuous cyclic peritoneal dialysis (CCPD) on a series of laboratory parameters in the blood and dialysate were assessed in two groups of nine juvenile diabetics each, suffering from terminal renal failure. The CCPD patients showed higher urea and creatinine levels in serum and, as a result of lower protein loss via the dialysate, also higher total protein and transferrin concentrations than the CAPD patients. The glucose absorption of the CCPD patients was about 50% lower than of the CAPD patients. Control of diabetes was equally successful with both procedures, the HbA1 values were less than 10%. The triglycerides were lowered by both CAPD and CCPD on the condition that the absorbed glucose amounts were included in the calculation of the dietary adjustment. Cholesterol and HDL-cholesterol remained unchanged. Thus CCPD appears to have advantages over CAPD, especially with respect to the lowering of the glucose absorption and the protein loss. The wider application of both methods will be, however, less influenced by the metabolic parameters than by other factors such as reduction of the risk of peritonitis.

Blood Glucose↗
PubMed1983

[Artificial blood. Experimental studies on fluorocarbons as chemical blood substitutes].

Fluorocarbonates are organic compounds capable of carrying oxygen and surrendering it to tissues by means of biological sound modalities. Experimentation of an emulsion consisting of perfluorotripropylamine and perfluorodecaline (Fluosol DA 20%) as a blood substitute is reported. Acute (Ht less than 1%) and chronic morphological (Ht = 15%) studies were performed on rats, and a semi-acute biochemical and morphological protocol (Ht = 21%) was experimented in pigs. The first signs of altered cerebral electrical activity occurred at Ht = 2% in the acute experiments, and death due to respiratory arrest took pace at Ht = 0.5%. In the semiacute and chronic experiments, widespread infiltration of fluorocarbonic micelles was noted on histological and electron microscope lung and liver preparations.

Acid-Base Equilibrium↗
PubMed1983

Proteins and glycoproteins of monkey and human platelets. Comparison by high resolution two-dimensional gel electrophoresis.

1. The protein and glycoprotein composition of the blood platelets of six primate species have been compared by high resolution two-dimensional polyacrylamide gel electrophoresis. 2. Only minor differences have been observed in the protein patterns of all six species. 3. The glycopeptide patterns of the monkey platelets five species) were rather uniform, but clearly different from the human pattern.

Animals↗
PubMed1982

Quinidine-digoxin interaction: evidence for involvement of an extrarenal mechanism.

The influence of quinidine 750mg per day for one week on serum digoxin concentration (SDC) was evaluated in digitalized anuric patients on chronic haemodialysis. During quinidine administration the SDC increased markedly, from 0.84 +/- 0.37 to 1.58 +/- 0.72 ng/ml (p less than 0.01), a comparable effect ot that reported previously in patients with normal renal function. Neither in vitro nor in vivo did quinidine alter the serum protein binding of digoxin. The increase in SDC in anuric patients indicates a decrease in the extrarenal clearance of digoxin, which means that mechanisms other than of renal origin are also involved in the interaction of quinidine and digoxin. There was great interindividual variability in the extent of the quinidine-induced rise in SDC. Regardless of the state of renal function, careful monitoring of digitalized patients seems mandatory once quinidine treatment is initiated.

Anuria↗