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Biomedical subjects

P Anderson

Publications and source records attributed to P Anderson.

At least 361 records · Page 20Linked to original sources
PubMed1988

Myosin heavy-chain mutations that disrupt Caenorhabditis elegans thick filament assembly.

We have investigated Caenorhabditis elegans mutants in which altered unc-54 myosin heavy-chain protein interferes with assembly of thick myofilaments. These mutants have a dominant, muscle-defective phenotype, because altered myosin heavy-chain B (MHC B), the product of the unc-54 gene, disrupts assembly of wild-type MHC B. The mutant MHC B also interferes with assembly of wild-type myosin heavy-chain A (MHC A), the product of another MHC gene expressed in body-wall muscle cells. Because of disrupted MHC A assembly, dominant unc-54 mutants also exhibit a recessive-lethal phenotype. Dominant unc-54 mutations are missense alleles, and the defects in thick filament assembly result from mutant protein that is of normal molecular weight. Accumulation of mutant MHC B in amounts as little as 2% of wild-type levels is sufficient to disrupt assembly of both wild-type MHC A and MHC B. Dominant unc-54 mutations occur at remarkably high frequency following ethylmethane sulfonate (EMS) mutagenesis; their frequency is approximately equal to that of recessive, loss-of-function mutations. This unusually high gain-of-function frequency implies that many different amino acid substitutions in the myosin heavy-chain B protein can disrupt thick filament assembly.

Actin Cytoskeleton↗
PubMed1988

Lysis of halobacteria in bacto-peptone by bile acids.

All tested strains of halophilic archaebacteria of the genera Halobacterium, Haloarcula, Haloferax, and Natronobacterium lysed in 1% Bacto-Peptone (Difco) containing 25% NaCl, whereas no lysis was observed with other strains belonging to archaebacteria of the genera Halococcus, Natronococcus, and Sulfolobus, methanogenic bacteria, and moderately halophilic eubacteria. Substances in Bacto-Peptone which caused lysis of halobacteria were purified and identified as taurocholic acid and glycocholic acid. High-performance liquid chromatography analyses of peptones revealed that Bacto-Peptone contained nine different bile acids, with a total content of 9.53 mg/g, whereas much lower amounts were found in Peptone Bacteriological Technical (Difco) and Oxoid Peptone. Different kinds of peptones can be used to distinguish halophilic eubacteria and archaebacteria in mixed cultures from hypersaline environments.

Journal Article↗
PubMed1988

Virulence properties and protective efficacy of the capsular polymer of Haemophilus (Actinobacillus) pleuropneumoniae serotype 5.

The role of the capsule of Haemophilus (Actinobacillus) pleuropneumoniae serotype 5 in bacterial virulence, and the protective efficacy of antibody to serotype 5 capsule was investigated. Encapsulated H. pleuropneumoniae serotype 5 were resistant to killing by complement and antibody to capsule or somatic antigens, whereas a noncapsulated mutant was sensitive to killing by the alternative complement pathway alone. Antiserum to whole H. pleuropneumoniae serotype 5 bacteria or monospecific antiserum to capsule was capable of opsonizing bacteria of the homologous serotype for phagocytosis by swine polymorphonuclear leukocytes but was not opsonic for a heterologous serotype. An immunoglobulin M monoclonal antibody to the serotype 5 capsule was not opsonic for any serotype. Mice were protected against lethal, intranasal challenge with the homologous or heterologous serotype after immunization with live encapsulated or noncapsulated bacteria, but not after immunization with killed bacteria, lipopolysaccharide, or a capsule-protein conjugate vaccine. The protection induced by immunization with live bacteria was transferred to nonimmune, syngeneic mice by serum but not by spleen cells. Nonimmune pigs passively immunized with monospecific swine serum to capsule were protected from lethal infection but not from development of hemorrhagic lung lesions, whereas pigs passively immunized with swine antiserum to live bacteria did not develop severe respiratory lesions. Thus, the capsule of H. pleuropneumoniae serotype 5 was inhibitory to the bactericidal activity of serum and was antiphagocytic. Antibody to the capsule was opsonic but was not fully protective.

Animals↗
PubMed1988

Regulatory myosin light-chain genes of Caenorhabditis elegans.

We have cloned and analyzed the Caenorhabditis elegans regulatory myosin light-chain genes. C. elegans contains two such genes, which we have designated mlc-1 and mlc-2. The two genes are separated by 2.6 kilobases and are divergently transcribed. We determined the complete nucleotide sequences of both mlc-1 and mlc-2. A single, conservative amino acid substitution distinguishes the sequences of the two proteins. The C. elegans proteins are strongly homologous to regulatory myosin light chains of Drosophila melanogaster and vertebrates and weakly homologous to a superfamily of eucaryotic calcium-binding proteins. Both mlc-1 and mlc-2 encode abundant mRNAs. We mapped the 5' termini of these transcripts by using primer extension sequencing of mRNA templates. mlc-1 mRNAs initiate within conserved hexanucleotides at two different positions, located at -28 and -38 relative to the start of translation. The 5' terminus of mlc-2 mRNA is not encoded in the 4.8-kilobase genomic region upstream of mlc-2. Rather, mlc-2 mRNA contains at its 5' end a short, untranslated leader sequence that is identical to the trans-spliced leader sequence of three C. elegans actin genes.

Amino Acid Sequence↗
PubMed1988

Insertion and excision of Caenorhabditis elegans transposable element Tc1.

The transposable element Tc1 is responsible for most spontaneous mutations that occur in Caenorhabditis elegans variety Bergerac. We investigated the genetic and molecular properties of Tc1 transposition and excision. We show that Tc1 insertion into the unc-54 myosin heavy-chain gene was strongly site specific. The DNA sequences of independent Tc1 insertion sites were similar to each other, and we present a consensus sequence for Tc1 insertion that describes these similarities. We show that Tc1 excision was usually imprecise. Tc1 excision was imprecise in both germ line and somatic cells. Imprecise excision generated novel unc-54 alleles that had amino acid substitutions, amino acid insertions, and, in certain cases, probably altered mRNA splicing. The DNA sequences remaining after Tc1 somatic excision were the same as those remaining after germ line excision, but the frequency of somatic excision was at least 1,000-fold higher than that of germ line excision. The genetic properties of Tc1 excision, combined with the DNA sequences of the resulting unc-54 alleles, demonstrated that excision was dependent on Tc1 transposition functions in both germ line and somatic cells. Somatic excision was not regulated in the same strain-specific manner as germ-line excision was. In a genetic background where Tc1 transposition and excision in the germ line was not detectable, Tc1 excision in the soma still occurred at high frequency.

Animals↗
PubMed1988

Structures of spontaneous deletions in Caenorhabditis elegans.

We have investigated the structural features of spontaneous deletions in Caenorhabditis elegans. We cloned and sequenced the junctions of 16 spontaneous deletions affecting the unc-54 myosin heavy-chain gene and compared their sequences with those of the wild type. We analyzed these sequences in an attempt to identify structural features of the gene that are consistently involved in the spontaneous deletion process. Most deletions (15 of 16) removed a single contiguous region of DNA, with no nucleotides inserted or rearranged at the deletion junctions; one deletion was more complex. unc-54 deletions were small, averaging 600 base pairs in length, and were randomly distributed throughout the gene. Unlike deletions that occur in Escherichia coli, spontaneous unc-54 deletions did not contain statistically significant direct or inverted repeats at or near their termini. Except for their small average size, we have not identified any distinguishing features of their sequence or structure. We discuss these results with regard to the mechanisms for spontaneous deletion in eucaryotic and procaryotic cells.

Alleles↗
PubMed1988

Traumatic atlanto-axial subluxation.

Traumatic atlanto-axial subluxation is a rare injury which may not be revealed on routine radiographs, especially when there is muscle spasm. We report on seven patients with atlanto-axial subluxation as a result of neck injury; only two of them had significant head injuries. Three patients presented with a neurological deficit attributable to the injury, one immediate and two with delayed onset. Traumatic atlanto-axial instability, occurring in an otherwise healthy patient, has a potential for neurological disaster; early consideration of operative treatment is indicated.

Adult↗
PubMed1988

A comprehensive indexed bibliography data base using a micro computer.

A comprehensive index has been developed for coding and cataloguing alcohol literature. A system has been implemented using a commercial data base management program and a micro computer for computerising the references. In addition to the index code and citation the user can also enter an abstract and a description of the article. References can be added to the computer, edited, searched for, displayed on screen, typed on paper, or sent to a text file using a selection of criteria entered by the user. When a search is performed the printout can include the abstract of each paper similar to that obtained from larger bibliographic services. Such a system is beneficial for personal study, for writing books, articles and theses and for use by departments and small libraries.

Abstracting and Indexing↗
PubMed1988

Liquid-chromatographic quantification compared with gas-chromatographic-mass-spectrometric determination of verapamil and norverapamil in plasma.

A high-performance liquid chromatographic (HPLC) method for determining verapamil and norverapamil in plasma is presented and compared with gas chromatography/mass spectrometry (GC-MS). The plasma samples were extracted at alkaline pH with hexane containing 2-butanol (20 mL/L) and then back-extracted into phosphate buffer (0.1 mol/L, pH 3.0). For chromatography we used a reversed-phase column (Supelcosil LC-18 DB) with a mobile phase of the phosphate buffer and acetonitrile (70/30 by vol). Fluorescence detection was used (excitation at 203 nm, emission at 320 nm). Overall analytical recovery was 85%. Standard curves were linear from 1 to 1000 micrograms/L. The detection limit was 1 microgram/L. The assays are accurate and precise. We found no interferences by those substances tested. Results by HPLC and GC-MS agreed well (r = 0.99) for both verapamil and norverapamil determinations.

Chromatography, High Pressure Liquid↗
PubMed1987

Cross-linking of T3 (CD3) with T4 (CD4) enhances the proliferation of resting T lymphocytes.

Monoclonal antibodies reactive with defined T lymphocyte surface antigens were covalently coupled to protein A-Sepharose beads using the bifunctional imidoester, dimethyl pimelimidate. Sepharose-immobilized antibody reactive with T3 induced the proliferation of resting T lymphocytes in the presence of either recombinant interleukin 2 or phorbol myristate acetate. When monoclonal antibodies reactive with T3 and T4 were coupled to the same Sepharose bead (hereafter designated Sepharose (T3:T4)), proliferation was enhanced an average of three-fold. Similarly prepared Sepharose beads coupled to anti-T3 and anti-T8 also enhanced proliferation over that observed with anti-T3 alone. Sepharose (T3:T4) similarly increased the proliferation of T4+ lymphocytes and a T4+ clone but failed to enhance the proliferation of T8+ lymphocytes. The increased proliferation of T4+ lymphocytes resulted from a preferential activation of the T4+2H4- helper population over the T4+2H4+ suppressor-inducer population. The enhanced proliferation induced by Sepharose (T3:T4) could be completely inhibited by soluble anti-T4. These results suggest that perturbation of T3 may be a minimal signal for T cell activation and that the assembly of a multimeric complex including T3 and T4 may be required for optimal T cell activation.

Antibodies, Monoclonal↗
PubMed1987

Verapamil and norverapamil in plasma and breast milk during breast feeding.

The concentrations of verapamil and norverapamil have been measured in milk and plasma samples from a 32 year-old woman treated with verapamil 80 mg tds while breast-feeding her child. The average steady-state concentrations of verapamil and noverapamil in milk were, respectively, 60% and 16% of the concentrations in plasma. The breast-fed child received less than 0.01% of the dose of verapamil given to the mother. No verapamil or norverapamil (less than 1 ng/ml) could be detected in the plasma from the child.

Adult↗