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J M Green

Publications and source records attributed to J M Green.

At least 19 recordsLinked to original sources
PubMed1992

Regulation of translation initiation factor gene expression during human T cell activation.

Activation of quiescent T cells leads to a dramatic increase in the rate of protein synthesis. It is believed that this pronounced increase of protein synthesis is regulated primarily at the level of translational initiation. Although considerable evidence demonstrates that translational initiation can be regulated at the post-translational level by the phosphorylation/dephosphorylation of translation initiation factors (eIFs) such as eIF-4E and eIF-2 alpha, additional mechanisms of eIF gene expression may also play a role in the regulation of translation in quiescent cells and/or during their subsequent induction to enter the cell cycle. To address this issue, gene expression of eIF-2 alpha, -4E, and -4A was studied in quiescent human peripheral blood T cells following stimulation through the T cell receptor-CD3 complex. Quiescent T cells expressed low levels of eIF-2 alpha, -4E, and -4A mRNAs and proteins as compared to proliferating T cells. Activation of resting T cells resulted in a rapid increase (20-50-fold) in the levels of these three mRNAs. This increase did not require new protein synthesis. Furthermore, transcription rates of these three eIF genes showed only minor increase over the induction period as measured by nuclear run-on assays. Despite the rapid increase in initiation factor mRNA levels, increases in eIF protein levels lagged significantly behind. Western blot analysis also showed that the protein levels of the three eIFs were differentially increased. eIF-4A protein levels increased in proportion to the observed increase in cellular protein synthetic activity while the increases in eIF-4E and eIF-2 alpha proteins were proportionately less. The low levels of eIF proteins in quiescent T cells appear to correlate with low protein synthesis rate in such cells. The induction of eIF proteins by post-transcriptional/translational mechanisms appears to contribute to the pronounced stimulation of protein synthesis that occurs during T cell activation.

Animals↗
PubMed1992

The epithelin precursor encodes two proteins with opposing activities on epithelial cell growth.

Epithelin 1 and 2 were originally purified from rat kidneys based on their ability to inhibit the growth of A-431 human epidermoid carcinoma cells (Shoyab, M., McDonald, V.L., Byles, C., Todaro, G.J., and Plowman, G.D. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 7912-7916). This study presents the complete amino acid sequence of these two growth factors and the cloning of their cDNA from rat, mouse, and human sources. Epithelins 1 and 2 are 56- and 57-amino acid polypeptides, respectively, and share 47% amino acid sequence identity with the conserved spacing of 12 cysteine residues. Molecular cloning revealed that both proteins are encoded by a single precursor that contains 7 1/2 copies of this novel 12-cysteine motif, 2 of which represent the known active molecules. Recombinant expression in COS cells demonstrated that the epithelin 1 protein was mitogenic on rodent keratinocytes and fibroblasts. In contrast, epithelin 2 had no activity on these cells, but at high concentrations was capable of antagonizing the growth proliferative activities of epithelin 1. Northern analysis shows the epithelin mRNA to be expressed in many types of epithelial cells. The broad expression profile of epithelin transcripts, along with the opposing activities of the two mature protein products, implicates these factors as natural mediators of epithelial homeostasis.

Amino Acid Sequence↗
PubMed1992

CD28 and staphylococcal enterotoxins synergize to induce MHC-independent T-cell proliferation.

The bacterial exotoxins staphylococcal enterotoxin A and B (SEA and SEB) mediate disease through their effects on T lymphocytes. In this manuscript we have demonstrated that both SEA and SEB can directly activate purified T cells in the absence of accessory cells as determined by a transition from G0 to G1 and induction of IL-2 receptor expression. However, neither SEA nor SEB alone was sufficient to result in T-cell proliferation. The induction of T-cell proliferation by SEB or SEA required the addition of a second costimulatory signal. This could be provided by either accessory cells or monoclonal antibody stimulation of CD28. As previously reported, T-cell proliferation induced by enterotoxin in the presence of accessory cells was partially inhibited by a blocking antibody against class II MHC. In contrast, in purified T cells when costimulation was provided through CD28, proliferation was not inhibited by class II antibody, and HLA-DR expression was not detectable. In addition, costimulation through CD28 was partially resistant to the effects of cyclosporin A. These results demonstrate that CD28 costimulation is sufficient to induce proliferation of enterotoxin-activated T cells, and that this effect is independent of class II MHC expression.

Antigens, CD↗
PubMed1992

Cytochrome-b sequence variation among parrots.

The nucleotide sequence of a 307 bp fragment of the mitochondrial cytochrome-b gene was determined for 12 species of parrot, using the polymerase chain reaction and direct sequencing. Sequence divergence ranged from 26-54 differences in pairwise comparisons, with the majority of base substitutions occurring at third positions of codons. The transition:transversion ratio was determined to be higher (approximately 24.3:1) in recently divergent parrot lineages than has generally been observed in other groups. Strongly biased base composition, particularly at the third position of codons, is evident among the sequences. Phylogenetic relationships among more divergent taxa were estimated, using only transversion substitutions, while all the substitutions were useful for closely related taxa. The African genera Psittacus and Poicephalus are closely related, in contrast to the Australian genera Nymphicus, Purpureicephalus and Melopsittacus, which represent more divergent lineages. The cockatoos appear to represent an ancient lineage within the parrots.

Animals↗
PubMed1992

Cloning and sequencing of Escherichia coli ubiC and purification of chorismate lyase.

In Escherichia coli, chorismate lyase catalyzes the first step in ubiquinone biosynthesis, the conversion of chorismate to 4-hydroxybenzoate. 4-Hydroxybenzoate is converted to 3-octaprenyl-4-hydroxybenzoate by 4-hydroxybenzoate octaprenyltransferase. These two enzymes are encoded by ubiC and ubiA, respectively, and have been reported to map near one another at 92 min on the E. coli chromosome. We have cloned the ubiCA gene cluster and determined the nucleotide sequence of ubiC and a portion of ubiA. The nucleotide sequence abuts with a previously determined sequence that encodes a large portion of ubiA. ubiC was localized by subcloning, and overproducing plasmids were constructed. Overexpression of ubiC allowed the purification of chorismate lyase to homogeneity, and N-terminal sequence analysis of chorismate lyase unambiguously defined the beginning of the ubiC coding region. Although chorismate lyase showed no significant amino acid sequence similarity to 4-amino-4-deoxychorismate lyase (4-amino-4-deoxychroismate----4-aminobenzoate), the product of E. coli pabC, chorismate lyase overproduction could complement the growth requirement for 4-aminobenzoate of a pabC mutant strain. Of the several enzymes that convert chorismate to intermediates of E. coli biosynthetic pathways, chorismate lyase is the last to be isolated and characterized.

Amino Acid Sequence↗
PubMed1992

Characterization and sequence of Escherichia coli pabC, the gene encoding aminodeoxychorismate lyase, a pyridoxal phosphate-containing enzyme.

In Escherichia coli, p-aminobenzoate (PABA) is synthesized from chorismate and glutamine in two steps. Aminodeoxychorismate synthase components I and II, encoded by pabB and pabA, respectively, convert chorismate and glutamine to 4-amino-4-deoxychorismate (ADC) and glutamate, respectively. ADC lyase, encoded by pabC, converts ADC to PABA and pyruvate. We reported that pabC had been cloned and mapped to 25 min on the E. coli chromosome (J. M. Green and B. P. Nichols, J. Biol. Chem. 266:12971-12975, 1991). Here we report the nucleotide sequence of pabC, including a portion of a sequence of a downstream open reading frame that may be cotranscribed with pabC. A disruption of pabC was constructed and transferred to the chromosome, and the pabC mutant strain required PABA for growth. The deduced amino acid sequence of ADC lyase is similar to those of Bacillus subtilis PabC and a number of amino acid transaminases. Aminodeoxychorismate lyase purified from a strain harboring an overproducing plasmid was shown to contain pyridoxal phosphate as a cofactor. This finding explains the similarity to the transaminases, which also contain pyridoxal phosphate. Expression studies revealed the size of the pabC gene product to be approximately 30 kDa, in agreement with that predicted by the nucleotide sequence data and approximately half the native molecular mass, suggesting that the native enzyme is dimeric.

Amino Acid Sequence↗
PubMed1992

Principles and practicalities of carrier screening: attitudes of recent parents.

Population carrier screening for cystic fibrosis could soon be a reality, but we know very little about people's attitudes towards genetic disease in general or cystic fibrosis in particular. This paper reports a study which aimed to investigate some of these attitudes and also to explore feelings about CF carrier screening given its practical limitations. The results are discussed in the context of earlier studies which have not raised these practical issues.

Cystic Fibrosis↗
PubMed1992

Intramedullary interlocked tibia nailing: a new technique (preliminary report).

This paper presents a modified surgical technique for interlocked intramedullary stabilization of tibia fractures. An external distractor is used to achieve an indirect fracture reduction on a fluoroscopy table. This method avoids the potential traction complications associated with conventional fracture tables. The fluoroscopy unit remains in one position during the entire operation. This technique decreases set-up time, provides complete control over the involved extremity, facilitates an accurate reduction, allows for compression at the fracture site, and simplifies the interlocking procedure. Twenty patients with 20 tibia shaft fractures were treated with this technique. No complications occurred during acute fracture care. Alignment was anatomic or near anatomic in all cases and physician satisfaction was 100%. At follow-up, averaging 5.2 months, there has been no change in fracture alignment, and most tibias are demonstrating clinical and radiographic healing. Distraction at the fracture site with a statically locked tibia nail may impede healing. The external distractor can be used to compress the fracture site prior to static interlocking, and this may facilitate healing. Dynamization of the nail should be considered when early signs of healing are absent. This technique is simple, accurate, and safe, and should be considered when treating an unstable tibia shaft fracture with a locked intramedullary nail.

Adolescent↗
PubMed1991

p-Aminobenzoate biosynthesis in Escherichia coli. Purification of aminodeoxychorismate lyase and cloning of pabC.

p-Aminobenzoate, a component of the vitamin folate, is one of seven compounds derived from the aromatic precursor chorismate in Escherichia coli. Historically the gene products of pabA and pabB were assumed to be sufficient for de novo p-aminobenzoate biosynthesis. Recent studies, however, have shown that these proteins, as nonidentical subunits of a single enzyme, act on chorismate to form a diffusible intermediate, most likely 4-amino-4-deoxychorismate. This intermediate is then converted to p-aminodeoxychorismate lyase (Nichols, B. P., Seibold, A. S., and Doktor, S. Z. (1989) J. Biol. Chem. 264, 8597-8601). Here we describe partial characterization of the intermediate and the purification of aminodeoxychorismate lyase 4100-fold to near homogeneity. Further purification of this enzyme by high pressure liquid chromatography permitted isolation of a pure sample that yielded N-terminal sequence. A 64-fold redundant oligonucleotide probe was used to identify a lambda clone containing the gene encoding aminodeoxychorismate lyase. The aminodeoxychorismate lyase gene, designated pabC, was mapped to 25 min on the E. coli chromosome and lies on a 7.5-kilobase pair EcoRI fragment. A strain harboring a pACYC184 recombinant containing pabC overproduced aminodeoxychorismate lyase activity 77-fold.

4-Aminobenzoic Acid↗
PubMed1991

EPDS by post.

Explore the source record for details and available documents.

Adult↗
PubMed1990

Stereotypes of childbearing women: a look at some evidence.

We all use stereotypes to help us to behave in what we hope will be appropriate ways towards people that we have not met before. On the labour ward midwives are likely to use such stereotypes to make assumptions about what a particular woman is likely to want during labour and delivery. Two commonly encountered stereotypes are those of the 'well educated, middle-class NCT type' and the 'uneducated working class woman'. This paper explores evidence for these two stereotypes drawing on data from a large scale prospective survey of women's expectations of childbirth. The stereotypes were not supported in a number of important respects. In particular: women of different levels of education were equally likely to subscribe to the ideal of avoiding drugs during labour; the less educated women did not want to hand over all control to the staff; it was less educated women who had the highest expectations that birth would be a fulfilling experience.

Attitude of Health Personnel↗
PubMed1990

Molecular cloning and expression of an additional epidermal growth factor receptor-related gene.

Epidermal growth factor (EGF), transforming growth factor alpha (TGF-alpha), and amphiregulin are structurally and functionally related growth regulatory proteins. These secreted polypeptides all bind to the 170-kDa cell-surface EGF receptor, activating its intrinsic kinase activity. However, amphiregulin exhibits different activities than EGF and TGF-alpha in a number of biological assays. Amphiregulin only partially competes with EGF for binding EGF receptor, and amphiregulin does not induce anchorage-independent growth of normal rat kidney cells (NRK) in the presence of TGF-beta. Amphiregulin also appears to abrogate the stimulatory effect of TGF-alpha on the growth of several aggressive epithelial carcinomas that overexpress EGF receptor. These findings suggest that amphiregulin may interact with a separate receptor in certain cell types. Here we report the cloning of another member of the human EGF receptor (HER) family of receptor tyrosine kinases, which we have named "HER3/ERRB3." The cDNA was isolated from a human carcinoma cell line, and its 6-kilobase transcript was identified in various human tissues. We have generated peptide-specific antisera that recognizes the 160-kDa HER3 protein when transiently expressed in COS cells. These reagents will allow us to determine whether HER3 binds amphiregulin or other growth regulatory proteins and what role HER3 protein plays in the regulation of cell growth.

Amino Acid Sequence↗
PubMed1990

Expectations, experiences, and psychological outcomes of childbirth: a prospective study of 825 women.

A prospective study of 825 women booked for delivery in six hospitals in southeastern England was conducted to determine their expectations of childbirth. Women completed three questionnaires, two before the birth and one six weeks after. Questions covered both objective and subjective aspects of birth, and gave particular attention to control, its importance and its relevance to psychological outcomes. Four different indices of psychological outcome were considered: fulfillment, satisfaction, emotional well-being, and the words that women used to describe their babies, which were shown to be related to different patterns of independent variables and of intrapartum events. Our results did not support popular stereotypes: high expectations were not found to be bad for women, although low expectations often were. Information and feeling in control were consistently associated with positive psychological outcomes.

Adolescent↗
PubMed1990

The amphiregulin gene encodes a novel epidermal growth factor-related protein with tumor-inhibitory activity.

We have isolated the gene for a novel growth regulator, amphiregulin (AR), that is evolutionarily related to epidermal growth factor (EGF) and transforming growth factor alpha (TGF-alpha). AR is a bifunctional growth modulator: it interacts with the EGF/TGF-alpha receptor to promote the growth of normal epithelial cells and inhibits the growth of certain aggressive carcinoma cell lines. The 84-amino-acid mature protein is embedded within a 252-amino-acid transmembrane precursor, an organization similar to that of the TGF-alpha precursor. Human placenta and ovaries were found to express significant amounts of the 1.4-kilobase AR transcript, implicating AR in the regulation of normal cell growth. In addition, the AR gene was localized to chromosomal region 4q13-4q21, a common breakpoint for acute lymphoblastic leukemia.

Amino Acid Sequence↗
PubMed1989

Large-scale purification and characterization of the Escherichia coli rep gene product.

We report a procedure for the large-scale purification of the Escherichia coli Rep protein, a helicase that is involved in the replication of the E. coli chromosome as well as a number of single-stranded bacteriophages. The procedure starts with E. coli cells harboring an overproducing plasmid, pRepO, in which the E. coli rep gene is under transcriptional control of the inducible lambda PL promoter (Colasanti, J., and Denhardt, D. T. (1987) Mol. Gen. Genet. 209, 382-390). The purification procedure results in greater than 98% pure Rep protein, which is free of contaminating nuclease activity, with yields of 40-50 mg of Rep protein/50 g of induced MZ-1/pRepO cells. We also show that cell death occurs upon inducing such a large overproduction of the E. coli Rep protein in MZ-1/pRepO. The Rep protein purified by this procedure has high specific single-stranded DNA-dependent ATPase activity, as well as helicase activity, with an apparent 3' to 5' directionality. The extinction coefficient of purified E. coli Rep protein is epsilon 280 = 1.16 +/- 0.04 ml mg-1 cm-1 (8.47 +/- 0.28 X 10(4) M-1 cm-1) in 10 mM Tris (pH 7.5), 20% (v/v) glycerol, 0.10 M NaCl at 25 degrees C. The solubility properties of the purified Rep protein have been examined as a function of glycerol, NaCl, MgCl2, ATP, and ADP concentrations at 25 and 37 degrees C (pH 7.5). Rep protein solubility decreases significantly with decreasing concentrations of glycerol and monovalent salt and increasing temperature; however, the presence of 1.5 mM ATP or ADP or MgCl2 at low NaCl concentrations increases the solubility. At 4 degrees C, in the presence of 20% glycerol and greater than or equal to 50 mM NaCl, the free Rep protein exists as a stable monomer under all conditions examined (+/- ATP and +/- MgCl2). The single-stranded DNA-dependent ATPase activity decreases with increasing glycerol concentration, such that in 25% (v/v) glycerol it has approximately 40% of its activity as compared to solutions that contain no glycerol. The dependence of the single-stranded DNA-dependent ATPase activity on salt concentration for a series of monovalent salts indicates the presence of both cation and anion effects, with decreasing activity in the order glutamate greater than acetate greater than chloride. The ability to obtain highly purified E. coli Rep protein in large quantities with relative ease will greatly facilitate physical characterizations of the protein and its interactions with DNA.

Adenosine Triphosphatases↗