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Biomedical subjects

K Schmid

Publications and source records attributed to K Schmid.

At least 145 records · Page 8Linked to original sources
PubMed1985

Occurrence of the Y determinant on the N-glycosidic carbohydrate units of human gamma-seminoprotein.

500-MHz H-NMR spectroscopy of the oligosaccharides derived from gamma-seminoprotein, a human seminal plasma glycoprotein, revealed considerable microheterogeneity both with respect to the degree of branching and with regard to the peripheral sugars. Although the protein possesses only one N-glycosylation site, di-, tri- and tetra-antennary glycans in a ratio of 40:15:45 were found to be present. Moreover, certain branches of the tri- and tetra-antennas contain one or two Fuc residues which form part of the SSEA-1 and Y determinants. It should be noted that this is the first report that describes the occurrence and localization of the Y determinant, i.e. Fuc alpha (1----2)Gal beta (1----4) [Fuc alpha (1----3)]GlcNAc beta (1----.), in an N-glycan of a glycoprotein.

Carbohydrate Conformation↗
PubMed1985

The amino acid sequence of human beta-microseminoprotein.

The complete amino acid sequence of beta-microseminoprotein of human seminal plasma was determined by automated Edman degradation of the protein and peptides which were obtained by enzymatic cleavage with trypsin, chymotrypsin and Staphylococcus aureus V8 proteinase. The carboxyl-terminal sequence of the protein was established with the aid of carboxypeptidase A. The amino acid sequence of this protein proved to be as follows: (sequence; see text) Thus, beta-microseminoprotein consisting of 93 amino acid residues has a molecular mass of 10 652 Da. The linear structure of this protein represents the first complete amino acid sequence of a sperm-coating protein specific to human seminal plasma.

Amino Acid Sequence↗
PubMed1985

How to identify compounds posing problems in absorption, distribution and elimination.

Absorption problems may be regarded mainly as compound inherent characteristics and are to a certain degree predictable on the basis of physicochemical parameters of test compounds. Problems originating from interactions of the compound and/or its metabolites with biological structures or processes are system inherent problems and can only be recognized by in vivo disposition studies of the compound. The examples given demonstrate clearly that preclinical absorption and disposition studies are of great help and in some cases even indispensable in planning of toxicity studies and in interpreting toxicity data.

Animals↗
PubMed1985

Medullary respiratory-related neurons with axonal connections to rostral pons and their function in termination of inspiration.

In urethane-anaesthetized, paralyzed and artificially ventilated rabbits, medullary respiration-related neurons (RRU) were classified according to the phase relation of their burst discharge to phrenic nerve activity. Phase-bound inspiratory (I) or expiratory (E) neurons were discriminated from phase-spanning expiratory-inspiratory (EI) or inspiratory-expiratory (IE) units. Mechanisms of termination of inspiration by electrical stimulation of rostral pontine nuclei (Nc. parabrachialis medialis; Lc. coeruleus) were examined firstly to demonstrate whether RRU receive descending excitatory and inhibitory afferents as well as ascending efferents and secondly to analyse the time course of the neuronal pathways involved. Of 120 RRU, 38 neurons were demonstrated to receive pontine afferents. About 33% of all E neurons became orthodromically excited during rostral pons stimulation whereas 18.2% of all I cells became orthodromically inhibited. Some RRU were shown to project up to the rostral pons. 50% of these were of the phase-spanning IE type. The onset of inspiratory inhibition induced by rostral pons stimulation occurred 3.4 ms after the onset of single electrical pulse stimulation. Based on these results a neuronal model for a pontine mechanism terminating inspiration is proposed.

Animals↗
PubMed1985

Cycle-triggered averaging of respiration-related neuronal activity.

A computer system is presented which provides off-line computation of cycle-triggered histograms (CTH) of respiration-related neuronal activity. Binwidths of the histograms are freely selectable by software from 10 ms to 100 ms. For special evaluation purposes, CTHs can be standardized in different ways concerning cycle duration as well as amplitude. Time incidence of maximum frequency, center of gravity and expiration-to-inspiration phase transition within the respiratory cycle are computed. The system employs special hardware interfaces to an 8-bit microcomputer which are briefly described. Data acquisition, data manipulation and output handling of the results are performed by chaining 3 compiled BASIC programs. Some comments on peculiarities of the BASIC language concerning combined application of a BASIC interpreter and a BASIC compiler are brought up. The usefulness of the method is demonstrated by examples of CTHs computed from the activity of medullary respiration-related neurons as well as of the corresponding phrenic nerve mass activity.

Animals↗
PubMed1985

Gabexate mesilate and camostate: new inhibitors of phospholipase A2 and their influence on the alpha-amylase activity in serum of patients with acute pancreatitis.

The new synthetic polyvalent protease inhibitors gabexate mesilate (ethyl-p[6-guanidinohexanoyloxy]-benzoate methansulfonate) and camostate (N,N-dimethylcarbamoylmethyl-4-[4-guanidinobenzoyloxy]-phenylacetate methansulfonate) were tested for possible inhibition of phospholipase A2 activity. In a pilot study, we treated 17 patients suffering from acute pancreatitis with continuous intravenous administration of gabexate mesilate, 450 mg/d. The results were compared with a placebo group (same standard therapy) of 21 patients suffering from acute pancreatitis. In vitro experiments showed that, at concentrations between 10(-4) and 5 X 10(-4) mol/L (depending on the enzyme assay employed) for gabexate mesilate and between 10(-3) and 5 X 10(-4) mol/L for camostate, a 50% reduction in phospholipase A2 activity was effected. Comparing the two groups of acute pancreatitis patients after 6 days of treatment with gabexate mesilate, we observed a statistically significantly lower alpha-amylase activity in the serum of treated patients compared with the placebo group.

Acute Disease↗
PubMed1985

Heterologous repressor-operator recognition among four classes of tetracycline resistance determinants.

Homologous and heterologous repressor-operator interactions among four different classes of tetracycline resistance determinants have been compared. These are represented by RP1/Tn1721 (class A), R222/Tn10 (class B), pSC101/pBR322 (class C), and RA1 (class D). By the use of the purified repressor proteins of class A (TetRA) and class B (TetRB), operator sequences of all four classes are recognized by both with an identical stoichiometry of four repressor subunits per control sequence, but with different affinities. In vitro transcription has been used to demonstrate regulatory activities of TetRA and TetRB upon all four classes of tet genes. Tetracycline acted as an inducer. A functional relationship among the tet regulatory systems was also shown in vivo by complementation of a class A tetR'-galK fusion mutant with the tetR genes of classes A, B, and C. Repression of tetRA-linked galactokinase was ca. 80% in the presence of tetRA or tetRC, and ca. 50% in the presence of tetRB. Taken together, these results demonstrate heterologous repressor-operator interaction, suggesting close relationships among the four classes of Tcr determinants.

Base Sequence↗
PubMed1984

The structure of the carbohydrate units of the carboxyl-terminal peptide of procollagen as elucidated by 500 MHz 1H-NMR spectroscopy.

The oligosaccharides of chick embryo type I procollagen were isolated from carboxyl-terminal propeptide fragment by exhaustive digestion with papain and pronase, and then purified as a mixture of glycopeptides. The structures of the oligosaccharides were established by high-resolution 1H-NMR spectroscopy and found to be a mixture with respect to the non-reducing terminal residues as shown below: (formula; see text) The percentages refer to the relative amount of those mannose residues present in the mixture. The data suggest that the oligosaccharides are a microheterogeneous mixture of high-mannose type glycans containing between six and nine mannose residues per carbohydrate unit. Such carbohydrate chains, although not uncommon for glycoproteins, had never been found before for collagen or collagen-related compounds.

Amino Acid Sequence↗
PubMed1984

The structure of the carbohydrate units of human plasma galactoglycoprotein determined by 500-megahertz 1H NMR spectroscopy.

Human plasma galactoglycoprotein (Mr = 81,000) which was recently identified and characterized (Schmid, K., Mao, S. K. Y., Kimura, A., Hayashi, S., and Binette , J. P. (1980) J. Biol. Chem. 255, 3221-3226) was found to possess an unusually high carbohydrate content (76%) comprised of NeuAc, Gal, Man, Fuc, GalNAc, and GlcNAc. The aim of the present investigation was to elucidate the primary structure of the oligosaccharide units of this protein. For the study of the O-glycosidic oligosaccharide chains, the protein was subjected to beta-elimination and the resulting oligosaccharide preparations were analyzed by 500-MHz 1H NMR spectroscopy. The structure of the predominant glycan, a hexasaccharide: (formula; see text) and that of a tetrasaccharide: NeuAc alpha(2----3)Gal beta(1----3)[NeuAc alpha (2----6)]GalNAc-ol, were determined. The protein possesses approximately 40 hexasaccharides and 3 tetrasaccharides/mol. For the isolation of its N-glycosidic oligosaccharide chains, the protein was exhaustively digested with proteases followed by chromatography of the desialyzed resulting glycopeptide fraction on concanavalin A-Sepharose. 500-MHz 1H NMR spectroscopy of the obtained preparations revealed the presence of 3 diantennary N-glycosidic chains that are extended with a Fuc residue at the Asn-linked GlcNAc.

Carbohydrate Sequence↗
PubMed1984

Three new restriction endonucleases MaeI, MaeII and MaeIII from Methanococcus aeolicus.

Three type II restriction endonucleases, MaeI, MaeII and MaeIII, with novel site specificities have been isolated and purified from the archaebacterium Methanococcus aeolicus PL-15/H. The recognition sequences of these enzymes are (formula: see text) with the sites of cleavage as indicated by the arrows. The sequences were confirmed by restriction and computer analyses on sequenced DNA's of plasmid pBR322, bacteriophages lambda and phi X174 and virus SV40.

Base Sequence↗