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Biomedical subjects

R Bach

Publications and source records attributed to R Bach.

At least 91 records · Page 5Linked to original sources
PubMed1985

Monoclonal antibodies against bovine tissue factor, which block interaction with factor VIIa.

Two monoclonal antibodies that recognize bovine tissue factor (coagulation factor III) have been obtained following the fusion of hyperimmune mouse spleen cells with NS-1 plasmacytoma cells. Both antibodies, TF1-E2 and TF1-F7, have gamma 1 heavy chains and lambda light chains. TF1-E2 and TF1-F7 have each been used to purify bovine tissue factor from a crude detergent extract of bovine brain by immunoaffinity chromatography. Both antibodies inhibit tissue factor procoagulant activity and block the association of factor VIIa with tissue factor. The association of TF1-F7 and tissue factor solubilized in Triton X-100 was measured under equilibrium conditions. The Kd for this antibody-antigen interaction was 2.1 +/- 0.2 nmol/L. TF1-E2 effectively competes with TF1-F7 for tissue factor binding, indicating that the monoclonal antibodies recognize overlapping sites on the protein. These antibodies will be useful reagents for large-scale purification and for structure-function studies of bovine tissue factor. In particular, since they appear to bind to the same region of the tissue factor molecule as factor VIIa, they will be useful as specific probes for studying the kinetics of tissue factor-initiated coagulation and for immunocytochemical localization of tissue factor in bovine cells.

Animals↗
PubMed1984

Intelligent computational assistance for experiment design.

We have developed an automated system for the design of laboratory experiments in molecular biology. The system uses a planning method known as skeletal plan refinement that attempts to emulate the human cognitive task of experiment design. This paper describes the theory, history, and implementation of the design system and illustrates its function in the domain of DNA cloning experiments.

Base Sequence↗
PubMed1984

Immunoaffinity purification of bovine factor VII.

Factor VII has been purified to homogeneity from bovine plasma by a procedure that includes affinity purification on an immunoadsorbent column. Recovery was determined by both coagulant assay and liquid scintillation counting, using 3H-factor VII as an internal standard. The purification factor calculated by both methods was approximately 120,000-fold, with a final yield of approximately 18%. Homogeneity was assessed by sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis. The material migrated as a single polypeptide chain of 53,000 daltons, and following activation by factor Xa, the one-chain zymogen was quantitatively converted to two-chain factor VIIa. Conversion of affinity-purified factor VII to factor VIIa resulted in up to a 119-fold activation of the coagulant activity, which is 2.7-4 times greater than the activatability reported for factor VII prepared by other methods. Zur et al. calculated that pure factor VII, uncontaminated by traces of factor VIIa, would be activated 123-fold upon conversion to factor VIIa. The close agreement between observed activatability of affinity-purified factor VII and the theoretical prediction suggests that we have isolated factor VII essentially free of factor VIIa. The purification data from three lots of bovine plasma yield an estimate for the plasma concentration of factor VII from 10.1 nM to 18.5 nM.

Animals↗
PubMed1983

Procoagulant activity associated with plasma membrane vesicles shed by cultured tumor cells.

Thirteen of 14 tumor cells or tumor cell lines of guinea pig, mouse, and human origin spontaneously shed procoagulant activity in short-term (4 or 14 to 22 hr) tissue culture under conditions of high cell viability. This released procoagulant activity was pelletable in the ultracentrifuge and was associated with plasma membrane-derived vesicles as determined by transmission electron microscopy and marker enzyme analysis. The procoagulant activity shed corresponded to a substantial fraction of that expressed by intact or sonicated tumor cells and was composed of activities interacting at more than a single step in the clotting sequence. One procoagulant activity associated with shed human tumor vesicles behaved as tissue factor, requiring Factor VII for activity and being inhibited by a specific anti-bovine tissue factor antibody. Guinea pig tumor vesicles also exhibited tissue factor-like activity in a two-stage assay using homologous first-stage Factor VII/X concentrate. None of the human vesicles tested expressed a direct Factor X cleaving activity, independent of Factor VII. Shed tumor vesicles also acted at a second step late in the clotting cascade at the level of prothrombinase generation, presumably by providing a phospholipid surface. Taken together, these data indicate that a wide variety of tumor cells release plasma membrane vesicles with procoagulant activity. Such vesicles, as well as intact tumor cells themselves, may play an important role in the biology of tumor growth by inducing the local fibrin deposits found in association with many solid tumors.

Animals↗
PubMed1982

MAXAMIZE. A DNA sequencing strategy advisor.

The MAXAMIZE advisory system determines from user-provided restriction maps an optimal strategy to do nucleotide sequencing by methods involving end-labeled fragments. The maps may be either simple linear restriction maps of fragments or complex circular maps including restriction sites of a vector. The whole system is interactive and is written in the Genetic English language provided by the GENESIS System, a molecular genetics knowledge representation and manipulation package. In addition, MAXAMIZE provides bookkeeping facilities for sequencing and offers advise on how to verify the newly obtained sequence data.

Base Sequence↗
PubMed1982

GENESIS, a knowledge-based genetic engineering simulation system for representation of genetic data and experiment planning.

We have built a knowledge-based genetic engineering simulation system-- GENESIS-- capable of representing both domain-specific and general knowledge. Information is stored within a hierarchically-organized framework composed of structures called units. A series of sophisticated editors enables no-computer specialist molecular geneticists to construct a knowledge base through direct interaction with the computer. Three types of knowledge specific to the domain of molecular genetics, MAPS, sequences and RULES are discussed in detail with examples.

Animals↗
PubMed1981

Sequence organization of the spacer in the ribosomal genes of Xenopus clivii and Xenopus borealis.

We have studied in X. clivii and X. borealis cloned EcoRI fragments containing the spacer located between the 28S and 18S ribosomal genes. We report for these two species the nucleotide sequences at both ends of the NTS region with special emphasis on the sequences around the transcription initiation site of the 40S rRNA precursor. In X. clivii the location of the 5' end of the precursor was mapped. In both species the sequences around the 40S origin are duplicated in the NTS. Nucleotide sequence comparison has revealed a stretch of 13 identical bases around the transcription initiation site of X. laevis and X. clivii. The same sequence is also present at the presumptive transcription initiation site of X. borealis rDNA.

Animals↗
PubMed1981

Purification and characterization of bovine tissue factor.

Tissue factor (tissue thromboplastin, factor III), an initiator of coagulation, has been purified 142,000-fold to homogeneity from bovine brain. The protein is an integral membrane glycoprotein with an apparent molecular weight of 43,000 as judged by sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis. The apoprotein was first purified by extraction with Triton X-100 and repeated preparative polyacrylamide gel electrophoresis in sodium dodecyl sulfate. Antiserum was produced against a few micrograms of purified apoprotein and was used to construct an immunoadsorbent column. The column was then used for affinity purification of the apoprotein directly from the Triton X-100 extract, thereby significantly increasing the amount of purified protein produced. The purification scheme may be generally useful for the rapid and large scale purification of membrane proteins. Tryptic digestion of the apoprotein in Triton X-100 cleaved a peptide of approximately 3000 daltons without affecting the activity. The activity was recovered directly from stained SDS polyacrylamide gels, and the profile of recovered activity corresponded directly with the stained bands. The activity shifted along with the protein band following tryptic digestion, thus demonstrating that the protein observed on the gels is tissue factor. The coagulant activity of the purified apoprotein was reconstituted by the addition of phospholipid. Optimal activity was observed at phospholipid to protein ratios (w/w) greater than 450:1.

Amino Acids↗
PubMed1981

The nucleotide sequence of the initiation region of the ribosomal transcription unit from mouse.

The 5' end of 45S pre-rRNA has been located on a cloned rDNA fragment from mouse by r-loop mapping and the nuclease S1 protection technique. 45S pre-rRNA could be shown to represent the primary transcript of the ribosomal genes because 5' polyphosphate termini have been detected by an enzymatic assay. The sequence of about 1100 nucleotides surrounding the initiation site for ribosomal RNA transcription has been determined. Features of this region of the ribosomal DNA will be discussed. A comparison of the nucleotide sequence with corresponding areas of ribosomal genes from other eukaryotes does not reveal significant homology in the region of transcription initiation.

Animals↗
PubMed1979

[Experience with cefaclor in the treatment of ear, nose and throat infections. Indications for cefaclor therapy (author's transl)].

The efficacy and tolerance of the new oral cephalosporin cefaclor was tested in 61 patients treated for a variety of moderate to severe ENT infections which were not expected to undergo a spontaneous remission without antibacterial therapy. The most frequently isolated pathogens were streptococci and Staphylococcus aureus. The dosage consisted of 500 mg cefaclor three times daily, and the treatment lasted between 4 and 43 days (average 14 days). In 35 cases, some of whom had already been treated unsuccussfully with another antibiotic, the results were very good. In 22 patients locally applied medicaments or surgery contributed to the good result. In four patients an unequivocal evaluation was not possible or therapy was not successful. The frequently noted rapid response to treatment with cefaclor was impressive. No relapses were recorded. In pharmacokinetic studies a cefaclor concentration of 2.8 mcg/g was obtained in the tonsils 90 minutes after oral administration of 1000 mg. Clinical examinations in 61 patients and a complete range of laboratory tests in 47 patients did not reveal any case of allergic reaction. One patient only complained of nausea and diarrhoea. In two patients temporary low grade thrombopenia and thrombocytosis respectively were observed. In several patients a slight transitory rise in transaminases was seen. Cefaclor thus proved to be an effective and well-tolerated antibiotic. Its indications in the treatment of ENT infections are discussed.

Adolescent↗
PubMed1979

Cefaclor in the treatment of infections of the ears, nose, and throat.

Clinical experience and laboratory tests in 52 patients (14 to 77 years of age) who had moderate to severe ear, nose, and throat infections were evaluated in this study of cefaclor, a new cephalosporin antibiotic, The drug proved to be effective in the treatment of these infections, and the incidence of side effects was low. Patients received oral doses of 500 mg every 8 hr for three to five days after all signs of infection had disappeared. Therapeutic results were assessed as very good in 31 patients, good in 17, and unsatisfactory in one. Three were unevaluable. The rapid onset of the therapeutic effect obtained with cefaclor in these patients was particularly striking. Some side effects occurred, but they were essentially transient and minor. Cefaclor should become a major antibiotic for the treatment of infections of the ears, nose, and throat.

Adolescent↗