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M C Smith

Publications and source records attributed to M C Smith.

At least 127 records · Page 7Linked to original sources
PubMed1993

Multiple novel promoters from the early region in the Streptomyces temperate phage phi C31 are activated during lytic development.

Evidence is presented that transcription of most of the early genes in the Streptomyces coelicolor A3(2) phage phi C31 is from a series of unusual promoters that depend on a function expressed early in the phi C31 lytic cycle. Primer extension analysis on the 5' ends of three early mRNAs, from samples prepared 10 min after induction of a thermosensitive phi C31 lysogen, showed that the 5' ends all mapped close to highly similar sequences, which are proposed to be an important part of phage-specific promoters. In a shotgun cloning experiment, a fragment containing one of these sequences strongly activated transcription of the xyIE reporter gene in plaques of a phi C31-derived promoter-probe vector. Another of the sequences was inserted into a xyIE-containing promoter-probe plasmid vector, and promoted xyIE expression only when the host was supporting the lytic cycle of phi C31. This suggested that a transcription factor needed for activity of the promoters was present only in phi C31-infected cells. Examination of published and unpublished phi C31 sequence data revealed several more sequences that closely resemble the conserved region of the characterized promoters. Most of these are found in positions close to apparent transcription start sites mapped previously by low-resolution S1 mapping. An overall consensus sequence for the conserved region suggests a general organization (though not a primary sequence) resembling that of promoters recognized in other bacteria by the sigma 54 form of RNA polymerase.

Bacteriophages↗
PubMed1993

The contribution of nursing theory to nursing administration practice.

The requisite theoretical base of nursing administration has been defined as a synthesis of knowledge from nursing and other disciplines. The purpose of this paper is to explore the contribution made by nursing knowledge to the distinctive epistemology of nursing administration. The value of nursing theory to administration practice is articulated as well as levels of theory development and their relationship to the knowledge base of nursing administration practice.

Environment↗
PubMed1993

Malnutrition in Iraqi children following the Gulf War: results of a national survey.

The community-based Iraq Infant and Child Mortality and Nutrition Survey was designed to estimate mortality and nutritional status of Iraqi infants and children under five years of age after the Gulf conflict of 1991. This article presents results from a nationwide nutritional survey conducted between August 25 and September 5, 1991. A random multistage cluster sample was selected, including a subsample of 2676 children in the anthropometric analysis. The percentage below -2 standard deviations was 21.8% for height-for-age, 11.9% for weight-for-age, and 3.4% for weight-for-height. It is possible that the observed prevalence of wasting was an underestimate, resulting from a survivor bias. This observation suggests that cross-sectional nutritional surveys may not be the most appropriate method for assessing the effect of the Gulf conflict on the nutritional status of children in Iraq. Longitudinal information on child mortality and nutritional status would be more useful in predicting the likelihood of famine.

Body Height↗
PubMed1993

Control of IgE responses. 4. Isotype-specific suppression of peak BPO-specific IgE antibody-forming cell responses and of BPO-specific IgE in serum by muramyldipeptide or murabutide after administration to mice by gavage.

Muramyldipeptide (MDP) and murabutide (MB) suppressed hapten-specific IgE antibody-forming cell (AFC) responses in vivo. IgE responses were induced in BALB/c mice by intraperitoneal injection with benzylpenicilloyl-keyhole limpet hemocyanin (BPO-KLH) (10 micrograms) in aluminum hydroxide gel (Alum) on days 0, 21 and 42. On day 44, mice were fed (gavage) or injected subcutaneously with varying concentrations of MDP or MB (0.1-500 mg/kg). The mice were killed on days 45-70, and the numbers of BPO-specific IgM, IgG1, IgE, and IgA AFC in various lymphoid organs were determined in an enzyme-linked immunosorbent spot (ELISPOT) assay. In addition, levels of BPO-specific IgE in serum were determined by ELISA. Data are expressed as AFC/10(7) cells or as micrograms/ml. Feeding with MDP or MB on day 44 suppressed BPO-specific IgE AFC responses and serum levels of BPO-specific IgE within 48 h (day 46) (65-100% and approximately 50% decrease, respectively). With both molecules, the suppression was IgE isotype-specific, dose-dependent and transient. The suppression was also route-specific since it was obtained only when MDP or MB were given by gavage, and not when injected subcutaneously. These results show that peak antigen-specific IgE responses can be downregulated in vivo, in isotype-specific fashion, by a clearly defined class of molecules, MDP and MB, one of which, MB, is a candidate for clinical studies in man. The mechanism of suppression probably involves the modulation of gut-associated lymphoid tissue and mucosal immunity. The clinical implications are that pharmacologic agents of this type may be suitable for use in the therapeutic or prophylactic downregulation of IgE and, hence, in the therapy of IgE-mediated diseases in man such as allergic rhinitis, asthma, and other atopic diseases.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1993

Future pharmacists and public initiatives to control retail drug prices: a political economy framework.

While pressures mount for public policy makers to intercede in the pricing structure of pharmaceutical products, most pharmacists remain reluctant to substitute generic equivalents for branded drugs. This study suggests that pharmacist' aversion to external factors embedded in their channel environments. An adaption of the political economy paradigm reflects the complexity of the pharmaceutical channel relationships.

Attitude of Health Personnel↗
PubMed1993

One-step purification of recombinant human papillomavirus type 16 E7 oncoprotein and its binding to the retinoblastoma gene product.

Six derivatives of the human papillomavirus type 16 E7 gene were constructed, each of which encoded a peptide at the amino terminus of the E7 protein capable of chelating metal ions, for use in subsequent purification of the proteins by chelating peptide-immobilized metal ion affinity chromatography (CP-IMAC). Five of the six chelating peptides examined contained six amino acids, and each varied in the number of histidine and tryptophan residues. The CP-E7 proteins were expressed in Escherichia coli, and the cysteine residues were blocked in the form of S-sulfonate groups. This series of CP-E7 proteins was purified in a single chromatographic step using CP-IMAC. The efficiency of purification correlated with the number of histidine and tryptophan residues present in the CP. The purified CP-E7 proteins bound to the human retinoblastoma gene product, pRB, in in vitro co-immunoprecipitation assays and immobilized CP-E7 binding assays. The efficiency of E7-pRB binding was not altered by the presence of a CP at the N-terminus of E7 nor by the S-sulfonate groups within E7.

Amino Acid Sequence↗
PubMed1992

Transcription map of the early region of the Streptomyces bacteriophage phi C31.

Streptomyces coelicolor A3(2), lysogenised by the temperature-sensitive cts1 mutant of phi C31, can be synchronously induced into the lytic cycle by heat treatment. A transcription map of 10 kb of the phi C31 early gene cluster was deduced using low-resolution S1 nuclease mapping of RNA prepared 10 min after induction. At least nine early transcripts, early (e)RNAs 1-9, were localised reading exclusively rightwards with respect to the standard physical map of phi C31. The mRNAs were extensively overlapping, frequently initiating at the same place but terminating at different sites, and vice versa. Gene expression during the lytic cycle was tightly regulated; no transcription was observed before induction. Transcription was maximal at 10 min post-induction, and at 20 min, eRNAs 5 and 6 persisted whilst eRNAs 7-9 were severely reduced or absent. The pattern of transcription of the early region is consistent with the simultaneous activation of a large number of promoters and differential termination efficiency.

Bacteriophages↗
PubMed1992

Effect of the Gulf War on infant and child mortality in Iraq.

BACKGROUND: Increased malnutrition and morbidity among Iraqi children after the onset of the Persian Gulf war have been reported by several fact-finding missions. The magnitude of the effect of the war and the economic embargo on child mortality remains uncertain, however. METHODS: We conducted a survey of 271 clusters of 25 to 30 households each, chosen as a representative sample of the Iraqi population. The households were selected and the interviews conducted by an international team of public health professionals independent of Iraqi authorities. In each household all women 15 to 49 years of age were interviewed, and the dates of birth and death of all children born on or after January 1, 1985, were recorded. RESULTS: The study population included 16,076 children, 768 of whom died during the period surveyed (January 1, 1985, to August 31, 1991). The age-adjusted relative mortality for the period after the war began, as compared with the period before the war, was 3.2 (95 percent confidence interval, 2.8 to 3.7). No material change in the relative risk was observed after adjustment for region of residence, maternal education, and maternal age. The increase in mortality after the onset of the war was higher among children 1 to less than 12 months old (relative risk, 4.1; 95 percent confidence interval, 3.3 to 5.2) and among those 12 to less than 60 months old (relative risk, 3.8; 95 percent confidence interval, 2.6 to 5.4) than among those less than 1 month old (relative risk, 1.8; 95 percent confidence interval, 1.4 to 2.4). The association between the war and mortality was stronger in northern Iraq (relative risk, 5.3) and southern Iraq (relative risk, 3.4) than in the central areas (relative risk, 1.9) or in Baghdad (relative risk, 1.7). CONCLUSIONS: These results provide strong evidence that the Gulf war and trade sanctions caused a threefold increase in mortality among Iraqi children under five years of age. We estimate that more than 46,900 children died between January and August 1991.

Child, Preschool↗
PubMed1992

Gene expression in the Streptomyces temperate phage phi C31.

The repressor gene, c, of the temperate Streptomyces phage, phi C31 was previously cloned and sequenced, and predicted to encode a 74-kDa protein. The c gene actually produces three in-frame, N-terminally different, C-terminally identical proteins of 74, 54 and 42 kDa. The repressor proteins are translated from a corresponding nest of transcripts. Genetic and biochemical evidence suggests that the transcription of the c locus is autoregulated possibly by the 42-kDa protein binding to a highly conserved 16-bp perfect inverted repeat. The 16-bp sequence is present at at least twelve loci throughout the phi C31 genome. Transcription of the 'early' region is complex, possibly involving phage-specific promoters. The phi C31 terminators display sequence conservation and may be regulated. The phi C31 gene 'k' may encode a nucleotide kinase-encoding gene.

Bacteriophages↗
PubMed1992

Purification and initial characterization of AhrC: the regulator of arginine metabolism genes in Bacillus subtilis.

The arginine-dependent repressor-activator from Bacillus subtilis, AhrC, has been overexpressed in Escherichia coli and purified to homogeneity. AhrC, expressed in E. coli, is able to repress a Bacillus promoter (argCp), which lies upstream of the argC gene. The purified protein is a hexamer with a subunit molecular mass of 16.7 kDa. Its ability to recognize DNA has been examined in vitro using argCp in both DNase I and hydroxyl radical protection assays. AhrC binds at two distinct sites within the argCp fragment. One site, argCo1, with the highest affinity for protein, is located within the 5' promoter sequences, whilst the other, argCo2, is within the coding region of argC. The data are consistent with the binding of a single hexamer of AhrC to argCo1 via four of its subunits, possibly allowing the remaining two subunits to bind at argCo2 in vivo forming a repression loop similar to those observed for the E. coli Lac repressor.

Amino Acid Sequence↗
PubMed1992

Sequence analysis of the beta-lactamase repressor from Staphylococcus aureus and hybridization studies with two beta-lactamase-producing isolates of Enterococcus faecalis.

The putative beta-lactamase (Bla) repressor gene, blaI, from the staphylococcal plasmid pI524 was isolated, and the DNA sequence was determined. The sequence of blaI was found to be identical to the blaI sequence from pI9789 (blaI blaZ seg-1), a plasmid related to pI524. A blaI probe from pI524 was hybridized with plasmid and genomic DNA from Bla+ Enterococcus faecalis isolates HH22 and PA. The Bla structural gene of HH22 has been previously shown to be of staphylococcal origin, but DNA homologous to the staphylococcal Bla repressor was not found, indicating that the constitutive production of beta-lactamase in these E. faecalis isolates may be the result of a missing repressor protein.

Base Sequence↗
PubMed1992

Comparison of enterococcal and staphylococcal beta-lactamase-encoding fragments.

A restriction map of a 13.5-kb EcoRI fragment encoding beta-lactamase from a plasmid isolated from enterococcal strain PA was prepared and found to differ markedly from the published maps of beta-lactamase-encoding EcoRI fragments of two staphylococcal plasmids and the plasmid from enterococcal strain HH22. This comparison also showed that one of two contiguous EcoRV fragments that encompass the beta-lactamase gene differs in size in the PA strain from that found in the other strains. However, restriction sites in the beta-lactamase structural gene (blaZ) were identical in all four plasmids. Further studies compared the beta-lactamase genes of four clinical enterococcal isolates from various geographic locations with those described above. Isolates from Virginia and Florida generated EcoRV fragments identical to those from the plasmid from strain PA, while isolates from Lebanon and Argentina showed EcoRV fragments analogous to those from HH22 and the staphylococci studied. Although there is evidence suggesting that some of these beta-lactamase-producing enterococcal isolates represent a single strain, this study indicates that there is significant variation in the plasmids that encode beta-lactamase.

Autoradiography↗