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M J Butler

Publications and source records attributed to M J Butler.

At least 19 recordsLinked to original sources
PubMed1995

Non-promoting effects of lean beef in the rat colon carcinogenesis model.

Recent epidemiologic studies have implicated red meat consumption as a risk factor for colon cancer in both men and women. However, it has been very difficult to separate the effects of meat as a protein source from the accompanying fat content of the diets analyzed in these studies. Experimental data from rodent feeding trials show mixed results, with no firm conclusions being possible in terms of the colon-cancer promoting effects of meat fat. The goal of the present study was to compare, in an experimental animal model, the effects of beef with casein as a protein source, within the context of a low- and high-fat diet containing either corn oil or beef tallow, on promotion of colon carcinogenesis. Tumors were induced in Sprague-Dawley rats with 1,2-dimethylhydrazine (20 mg/kg body wt for 10 weeks). Two hundred and eighty male weanling rats were randomized to eight dietary treatment groups of a 2x2x2 factorial design with fat source (corn oil vs. beef tallow), fat level (5% vs. 20%), and protein source (very lean beef vs. casein) as the factors. Diets were fed ad libitum before, during and after carcinogen treatment for a total of 27 weeks. At termination of the study, animals were examined for location, size and type of colon or extracolonic lesions. The total incidence and number of colon tumors were significantly lower in the groups fed beef rather than casein. High fat levels, regardless of source, significantly increased the number of colon adenomas. These results demonstrate that when lean beef is used as the protein source in the context of a low-fat diet, fewer intestinal tumors develop. These data do not support the belief that red meat consumption increases the risk for colon carcinogenesis, but underscores the importance of fat level in dietary context.

1,2-Dimethylhydrazine↗
PubMed1995

Cloning and characterization of a gene encoding a secreted tripeptidyl aminopeptidase from Streptomyces lividans 66.

The gene encoding a tripeptidyl aminopeptidase (Tap) from Streptomyces lividans was cloned by using a simple agar plate activity assay. Overexpression of the cloned gene results in the production of a secreted protein which has an apparent subunit molecular weight of 55,000 and is responsible for the major amino-terminal degradative activity in culture broths of S. lividans strains. A DNA sequence analysis revealed a potential protein-encoding region of the size expected to encode the observed protein, which contained a sequence that exhibited significant homology around a putative active site serine residue observed for lipases, esterases, and acyl transferases. Preceding the amino terminus of the secreted protein was a predicted signal peptide of 36 amino acids followed by a tripeptide, which could be autocatalytically removed from a secreted Tap precursor. The transcriptional start site for the gene was mapped by primer extension. Mutant strains of S. lividans lacking detectable Tap activity were able to grow and sporulate normally. Cross-species hybridization experiments showed that DNA homologs of the tap gene are present in most of the Streptomyces strains tested.

Amino Acid Sequence↗
PubMed1995

Isolation and characterization of two genes encoding proteases associated with the mycelium of Streptomyces lividans 66.

A strain of Streptomyces lividans 66 deleted for a major tripeptidyl aminopeptidase (Tap) was used as a host to screen an S. lividans genomic library for clones overexpressing activity against the chromogenic substrate Ala-Pro-Ala-beta-naphthylamide. In addition to reisolation of the tap gene, clones representing another locus, slpD, were uncovered. slpD was analyzed by deletion subcloning to localize its functional sequence. Nucleotide sequence determination revealed an open reading frame encoding a 55-kDa protein exhibiting significant amino acid sequence homology to Tap, particularly around the putative active-site serine residue. No secreted protein was observed for strains harboring the slpD clone, but inspection of the predicted protein sequence revealed a putative lipoprotein signal peptide (signal peptidase II type), suggesting a mycelial location for the SlpD proteinase. In an attempt to isolate an endoprotease known to be active against some heterologous proteins, a second clone was isolated by using a longer substrate (t-butyloxycarbonyl [Boc]-APARSPA-beta-naphthylamide) containing a chemical blocking group at the amino terminus to prevent aminopeptidase cleavage. This locus, slpE, appeared to also encode a 55-kDa mycelium-associated (lipoprotein) proteinase, whose predicted protein sequences showed significant amino acid homology to Tap and SlpD, particularly around the putative active-site serine residues. Chromosomal integration and deletion analysis in both the wild-type and Tap-deficient backgrounds appeared to indicate that SlpD was essential for viability and SlpE was required for growth on minimal media.

Amino Acid Sequence↗
PubMed1995

Domestic violence: a nursing imperative.

This manuscript describes female partner abuse and reviews its significance to health care providers. Attention is given to the essential nursing roles of screening for abuse, intervening with women at risk for abuse, and completing a needed examination when abuse has occurred. Ideas for an expanded nursing role are provided.

Female↗
PubMed1994

The aminopeptidase N-encoding pepN gene of Streptomyces lividans 66.

The gene (pepN) encoding an aminopeptidase N (PepN) has been cloned from Streptomyces lividans. This was done using either leucine-beta-naphthylamide or arginine-beta-naphthylamide in a liquid overlayer on colonies growing on agar medium to screen for overproduction of the ability to hydrolyse the substrates. The nucleotide sequence of pepN was determined and shown to encode a 95-kDa protein, which displayed significant homology to PepN proteins from other organisms. Analysis of the overproduced proteinase confirmed that this protein was located intracellularly as a monomeric active species. PepN is a metallo-exopeptidase cleaving next to Leu, Arg and Lys in peptide-bond-containing substrates.

Amino Acid Sequence↗
PubMed1994

Intracellular aminopeptidases in Streptomyces lividans 66.

We have investigated the aminopeptidase activities present in Streptomyces lividans strains. The majority of these activities proved to be intracellular with multiple active species. Two aminopeptidase P genes were identified to be responsible for the ability to hydrolyze amino terminal peptide bonds adjacent to proline residues. Two other broad spectrum aminopeptidases were found to display homology at both the DNA and protein levels. One showed significant homology to PepN proteins, particularly around the putative zinc-binding residues which are important for catalysis. The second broad spectrum activity was not analyzed in detail but showed a different spectrum of substrate specificity to that of PepN.

Amino Acid Sequence↗
PubMed1992

Cloning of genetic loci involved in endoprotease activity in Streptomyces lividans 66: a novel neutral protease gene with an adjacent divergent putative regulatory gene.

A skimmed-milk clearing assay was used to identify, in a multicopy Streptomyces lividans 66 genomic library, DNA fragments that lead to increased expression of protease activity in S. lividans 66. Three independent loci were identified. The majority class (slpA, which represented 68 of 71 clones) produced large zones of clearing. Two other classes (designated slpB and slpC) showed smaller zones than slpA. Subcloning and deletion analysis of the slpA locus delineated the relevant DNA to within a 2.5 kilobase pair fragment. DNA sequence analysis revealed a structural gene associated with the appearance of an extracellular protein in the culture medium. The derived amino acid sequence indicated the presence of a zinc-binding motif, which was previously noted to be characteristic of metalloprotease enzymes. However, the relatively small size of the protein (apparent molecular weight 20,000-24,000) suggests that it represents a novel class of neutral proteases distinct from the thermolysin-type enzymes. An adjacent divergent open reading frame was identified and shown to cause a significant increase in protease activity when present together with the protease structural gene on a multicopy plasmid in S. lividans 66. The derived amino acid sequence of this open reading frame showed homology with previously characterized regulatory proteins of the LysR family of transcriptional regulator proteins.

Amino Acid Sequence↗
PubMed1991

Characterization of an oxytetracycline-resistance gene, otrA, of Streptomyces rimosus.

The sequence of a 2657 bp DNA fragment containing the coding and regulatory regions of the oxytetracycline (OTC)-resistance gene, otrA, from the OTC producer Streptomyces rimosus was determined. The predicted amino acid sequence of OtrA had extensive identity with tetracycline-resistance genes from other bacteria which mediate resistance via non-covalent ribosomal modification. The N-terminal domain had extremely high identity with the GTP-binding sites of elongation factors, such as EF-G and EF-Tu, suggesting that binding and hydrolysis of GTP is important to the function of the protein. Significant identity with EF-G was present throughout the polypeptide. Transcriptional activity upstream of the otrA coding region was investigated. An Escherichia coli-type promoter, otrAp1, was identified. Transcriptional readthrough of otrA from the upstream gene (otcZ) was also detected in S. rimosus cultures. A divergent promoter activity was identified with subclones of the OtrA fragment in promoter probe vectors analysed in Streptomyces lividans. However, this activity was not identified in a subclone containing more than half of the otrA coding sequence in S. lividans or at all in S. rimosus, indicating that OtrA negatively regulates the expression of the divergent transcript. The data are consistent with regulation of antibiotic production by OtrA to prevent 'suicide'.

Amino Acid Sequence↗
PubMed1991

Beyond abuse: Parse's theory in practice.

A nursing practice with abused women and their families based on Parse's theory of Man-Living-Health is described with emphasis on implementation of the practice processes flowing from the theory and common outcomes of the processes. A case study is presented to illustrate how the practice processes aided one couple in transforming from an abusive relationship to a new and valued way of coexisting. Information on the nursing practice and the case study are used to help demonstrate the utility of the theory of Man-Living-Health in enhancing the quality of life.

Adult↗
PubMed1989

Molecular cloning of resistance genes and architecture of a linked gene cluster involved in biosynthesis of oxytetracycline by Streptomyces rimosus.

The isolation of mutants of Streptomyces rimosus which were blocked in oxytetracycline (OTC) production was described previously. The genes for the early steps of antibiotic biosynthesis mapped together. Genomic DNA fragments of S. rimosus which conferred resistance to OTC and complemented all of these non-producing mutants have been cloned. The cloned DNA is physically linked within approximately 30 kb of the genome of S. rimosus. The gene cluster is flanked at each end by a resistance gene each of which, independently, can confer resistance to the antibiotic. In OTC-sensitive strains of S. rimosus, the entire gene cluster including both resistance genes has been deleted. Complementation of blocked mutants by cloned DNA fragments in multi-copy vectors was often masked by a secondary effect of switching off antibiotic production in strains otherwise competent to produce OTC. This adverse effect on OTC production was not observed with recombinants using low copy-number vectors.

Cloning, Molecular↗
PubMed1989

Cloning and heterologous expression in Streptomyces lividans of Streptomyces rimosus genes involved in oxytetracycline biosynthesis.

The anhydrotetracycline (ATC) oxygenase enzyme which carries out the conversion of ATC to dehydrotetracycline was purified and the N-terminal amino acid sequence was determined. The sequence displays a significant similarity to that of the p-hydroxybenzoate hydroxylase from Pseudomonas fluorescens. This is consistent with the activity of the oxygenase, i.e., addition of a hydroxyl moiety to an aromatic ring structure. Oligonucleotide probes were designed and used to clone the corresponding fragment of chromosomal DNA from Streptomyces rimosus. This DNA fragment was used to screen a cosmid library, allowing the isolation of flanking DNA sequences. Surprisingly, the gene was located within the previously cloned cluster of genes involved in the synthesis of the biosynthetic intermediate ATC and not as had been expected (P. M. Rhodes, N. Winskill, E. J. Friend, and M. Warren, J. Gen. Microbiol. 124:329-338, 1981) at a separate locus on the other side of the chromosome. Subcloning of an appropriate DNA fragment from one of the cosmid clones onto pIJ916 produced Streptomyces lividans transformants which synthesized oxytetracycline.

Amino Acid Sequence↗
PubMed1987

The use of N,N,N',N'-tetramethylphenylenediamine to detect peroxidase activity on polyacrylamide electrophoresis gels.

N,N,N',N'-Tetramethylphenylenediamine (TMPD) acts as an effective indicator of peroxidase activity on polyacrylamide electrophoresis gels. The test is easy to perform, rapid, sensitive, and reliable. The procedure produces vivid bright blue bands (Wursters blue) on a clear background. TMPD and Wursters blue did not interfere with a number of other electrophoresis stains subsequently applied. These included total protein staining with Coomassie blue, and a number of pigment producing electrophoresis stains used to investigate melanogenesis-related enzymes in the black yeast Phaeococcomyces sp.

Chromogenic Compounds↗
PubMed1986

Nonhemorrhagic cerebral infarction in young adults.

We evaluated 144 patients (81 males and 63 females) aged 15 to 45 years who had nonhemorrhagic cerebral infarction. Atherosclerotic cerebral infarction was diagnosed in 38 patients. Potential cardiac causes of cerebral embolism were found in 33 patients. Only three events could be attributed to mitral valve prolapse. Hematologically related disorders were diagnosed in 21 patients, while 38 patients had nonatherosclerotic vasculopathies. Young patients with cerebral infarction are a heterogeneous group. A potential cause can be found in most patients. We found more than 40 possible etiologies among our patients. Mitral valve prolapse apparently is not a common cause of cerebral infarction among young adults. Cerebral infarction should not be ascribed to oral contraceptives or migraine until other possible causes have been eliminated.

Adolescent↗
PubMed1986

Properties of in vitro recombinant derivatives of pJV1, a multi-copy plasmid from Streptomyces phaeochromogenes.

The 10.8 kb plasmid pJV1, isolated from Streptomyces phaeochromogenes, has a high copy number (about 150) and a broad host range among Streptomyces spp. Several pJV1 derivatives carrying the thiostrepton resistance gene (tsr) of S. azureus were made. One derivative, pWOR191, was shown to promote its own transfer and to mobilize chromosomal markers in S. lividans. Another derivative, pWOR109, was non-transmissible. Deletion in vitro of a segment of pWOR109 gave pWOR120 (5.6 kb), which has single BamHI and Bg/II sites shown to be capable of accepting 'foreign' DNA such as a previously cloned S. antibioticus DNA fragment encoding tyrosinase, giving vectors (pWOR125, pWOR126) with properties resembling the well-established multicopy vector pIJ702. Shuttle vectors capable of functioning in both S. lividans and Escherichia coli were also constructed. The region of pJV1 essential for replication and maintenance was localized to a 2.5 kb segment. Stable maintenance of pWOR109 and pWOR120 was observed in the presence of derivatives of pIJ101, the progenitor of pIJ702.

Chromosomes, Bacterial↗
PubMed1985

Aphasia following pluridirectional tomography with metrizamide. The effect of patient position.

Eight of 67 patients became transiently aphasic after myelography or cisternography with metrizamide. All eight patients had been placed in the left lateral decubitus position for pluridirectional tomography. Immediate EEGs revealed focal left-sided abnormalities in two patients. In one other patient, a computed tomographic scan showed contrast mainly over the left hemisphere. All of the symptoms resolved within 48 hours. In 34 patients who were placed on the right side, no language disturbance was noted. Aphasia after pluridirectional tomography with metrizamide may be due to local irritation of the perisylvian language centers of the dominant hemisphere. The phenomenon is distinct from syndromes of generalized confusion. The complication may be avoided by placing patients in a right lateral decubitus position for pluridirectional tomography.

Adult↗
PubMed1985

Intramuscular acupuncture-like electrical stimulation inhibits stretch reflexes in contralateral finger extensor muscles.

Electro-acupuncture is one of many physical measures used to relieve musculoskeletal pain and to improve the associated restricted range of motion. Experiments were designed to determine whether or not acupuncture-like stimulation inhibits stretch reflexes in an arm extensor muscle in human volunteers. Surface electromyographic recordings were made on the right extensor digitorum communis muscle and averaging techniques were used to study the reflex responses to brief deflection of the finger with a solenoid-driven probe. The ratio M1:M2 of two components of the reflex was reduced during continuous acupuncture-like stimulation of the contralateral first dorsal interosseus and extensor digitorum communis muscles near their motor points (acupuncture points LI 4 and LI 11). Concomitant changes in skin temperature were observed on the forehead and in the arm in which acupuncture-like stimulation was used. In control experiments, when the acupuncture needles were inserted subcutaneously and stimulated with the same current parameters at distinctly uncomfortable intensities, no change in the reflexes occurred. These findings show that acupuncture-like stimulation exerts physiologic effects on the central nervous system, mediated presumably by muscle afferent fibers. The effects may be relevant to relief of muscle spasm and musculoskeletal pain, and restoration of mobility.

Arm↗