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T Evans

Publications and source records attributed to T Evans.

At least 181 records · Page 10Linked to original sources
PubMed1988

A promoter of the rat insulin-like growth factor II gene consists of minimal control elements.

We have characterized the cis-control signals in one of the two promoters of the developmentally regulated rat insulin-like growth factor II gene (rIGF-II) by a combination of in-vivo transient expression, in-vitro transcription, footprinting, gel band-shifting and methylation-interference experiments, using a series of deletion mutant templates. Our results indicate that this simple (minimal) promoter (P2) consists of no more than 128 base-pairs, which include an ATA box and four proximal upstream GC boxes binding the general transcription factor Sp1. Three of the latter sites deviate from the known Sp1 consensus recognition sequence. The two types of cis-acting regulatory signals (GC/ATA motif) of the P2 promoter are inter-dependent and sufficient for transcription. A model for the operation of this type of minimal promoter is discussed. S1 nuclease-hypersensitive sites, localized by in-vitro mapping to the region of the P2 Sp1-binding sites, are also present in vivo and correlate with the transcriptional state of chromatin in the rIGF-II locus. We show that recognition sites for Sp1 binding are a subset of sequences that exhibit hypersensitivity to S1.

Animals↗
PubMed1988

An erythrocyte-specific DNA-binding factor recognizes a regulatory sequence common to all chicken globin genes.

We have identified a protein present only in erythroid cells that binds to two adjacent sites within an enhancer region of the chicken beta-globin locus. Mutation of the sites, so that binding by the factor can no longer be detected in vitro, leads to a loss of enhancing ability, assayed by transient expression in primary erythrocytes. Binding sites for the erythroid-specific factor (Eryf1) are found within regulatory regions for all chicken globin genes. A strong Eryf1 binding site is also present within the enhancer of at least one human globin gene, and proteins from human erythroid cells (but not HeLa cells) bind to both the chicken and the human sites.

Animals↗
PubMed1988

Early diagnosis of myocardial infarction by timed sequential enzyme measurements.

Serum samples from patients admitted to a coronary care unit with a history of acute chest pain suggestive of myocardial infarction in the previous 12 h were obtained on admission and at 6 and 12 h, thereafter. Creatine kinase (CK), CK-MB isoenzyme, CK-MM sub-bands, myoglobin, and lactate dehydrogenase (LD) isoenzymes were examined. Changes were evaluated in relation to the diagnosis obtained from clinical examination, serial electrocardiography and 'routine' cardiac enzymes (CK, aspartate transaminase and alpha-hydroxy butyrate dehydrogenase daily for 3 days following admission). The slope of the logarithms of CK, CK-MB activity and CK-MB concentration in the early post infarct period fully distinguished between infarct and non-infarct patients. Measurement of myoglobin and lactate dehydrogenase isoenzymes was less sensitive. Serial estimation of CK-MM sub-band patterns allowed the time from infarction to be estimated. Serial estimation of CK in the 12 h following admission can be substituted for conventional daily enzyme estimations for the diagnosis of acute myocardial infarction in patients with onset of chest pain within the previous 12 h. This could reduce laboratory and in-patient costs.

Adult↗
PubMed1988

Biologically active, derivatizable salmon calcitonin analog: design, synthesis, and applications.

An analog of salmon calcitonin (sCT) has been synthesized, substituting Arg at positions 11 and 18 and Lys at position 14 to provide a free amino group for derivatization. The potency of [Arg11,18,Lys14]sCT was equivalent to that of sCT in activating adenylate cyclase in UMR 106-06 cells. The analog was derivatized with biotin, fluorescein, or 4-azidobenzoate without loss of activity. The derivatized analog was not degraded by lysine-specific endoprotease, whereas the underivatized [Arg11,18,Lys14]sCT was cleaved at Lys-14. The derivatized analogs were purified by HPLC and subsequently shown to possess full biological activity. The photoactive analog was used to photolabel 88,000 and 71,000 mol wt components of the calcitonin receptor in rat osteoclasts, but only an 88,000 mol wt component was photolabeled in the UMR 106-06 cells.

Adenylyl Cyclases↗
PubMed1987

Identification and purification from bovine brain of a guanine-nucleotide-binding protein distinct from Gs, Gi and Go.

A guanine-nucleotide-binding protein (G-protein) was purified from cholate extracts of bovine brain membranes by sequential DEAE-Sephacel, Ultrogel AcA-34, heptylamine-Sepharose and Sephadex G-150 chromatography. Guanosine 5'-[gamma-[35S]thio]triphosphate (GTP[35S])-binding activity copurified with a 25,000 Da peptide and a 35,000-36,000 Da protein doublet. Neither pertussis toxin nor cholera toxin catalysed the ADP-ribosylation of a protein associated with the GTP[35S]-binding activity. Photoaffinity labelling of the purified protein with 8-azido[gamma-32P]GTP indicated that the GTP-binding site resides on the 25,000 Da protein. The 35,000-36,000 Da protein doublet was electrophoretically indistinguishable from the beta-subunits of other GTP-binding proteins, and the 36,000 Da protein was recognized by antiserum to oligomeric Gt. The purified protein specifically bound 17.2 nmol of GTP[35S]/mg of protein. The Kd of the binding site for radioligand was approx. 15 nM. The brain GTP-binding protein co-migrated during SDS/polyacrylamide-gel electrophoresis with a GTP-binding protein, named Gp, purified from human placenta [Evans, Brown, Fraser & Northup (1986) J. Biol. Chem. 261, 7052-7059], and cross-reacted with antiserum raised against the placental protein, but not with antiserum raised to brain Go. SDS/polyacrylamide-gel electrophoresis of the brain and placental GTP-binding proteins in the presence of Staphylococcus aureus V8 protease yielded identical peptide maps.

Animals↗
PubMed1987

Norfloxacin in the treatment of uncomplicated gonococcal infections.

Norfloxacin, an oral fluoroquinolone antibacterial, is active in vitro against a variety of gram-positive and gram-negative pathogens, including both penicillinase-producing and non-penicillinase-producing strains of Neisseria gonorrhoeae. An earlier study demonstrated that a two-dose regimen of norfloxacin was as effective as standard therapy with spectinomycin for treating gonococcal urethritis, including infections caused by penicillinase-producing organisms. In this randomized study of treatment for uncomplicated gonococcal infection in men and women, three oral treatment regimens were compared: patients received either two doses of norfloxacin (600 mg twice daily), a single dose of norfloxacin (800 mg), or a single-dose ampicillin (3.5 g)/probenecid (1.0 g) regimen (as recommended by the Centers for Disease Control). All three treatment regimens achieved similar cure rates. Although the number of patients treated was too small to yield statistically significant conclusions, it appears that norfloxacin may be slightly better treatment for rectal and pharyngeal gonococcal infections than ampicillin and probenecid. Additionally, norfloxacin was well tolerated in this study. Thus, based on a review of these data, norfloxacin appears to be an alternative, single-dose, oral treatment regimen for uncomplicated gonococcal infection.

Adult↗
PubMed1987

Purification of a beta 35 form of the beta gamma complex common to G-proteins from human placental membranes.

The significance of the 36,000-35,000-dalton doublet of proteins referred to as the beta-subunit of the G-proteins remains unresolved. An immunological distinction between the 36,000 (beta 36)- and 35,000 (beta 35)-dalton proteins has been reported (Roof, D. J., Applebury, M. L., and Sternweis, P. C. (1985) J. Biol. Chem. 260, 16242-16249; Mumby, S. M., Kahn, R. A., Manning, D. R., and Gilman, A. G. (1986) Proc. Natl. Acad. Sci. U.S.A. 83, 265-269). The availability of homogeneous preparations of beta 36 and beta 35 will facilitate studies designed to address the significance of the doublet structure. This manuscript presents the preparative purification of the beta 35 protein from a highly enriched source, human placenta. Unlike the beta gamma complex associated with G-proteins from placenta, the beta 35 preparations consist predominantly of the 35,000-dalton protein. The gamma-peptide associated with beta 35 is indistinguishable electrophoretically and immunologically from that associated with the placental G-protein oligomers. The beta 35 preparation and beta-subunit doublet exhibit similar specific activities in inhibiting human platelet adenylate cyclase activity. The preparations have proven useful for the generation of a panel of rabbit polyclonal antisera that recognize beta 35, Gt beta 36, and both beta 36 and beta 35 in the doublet associated with Gs, Gi, Go, and Gp. One antiserum generated to beta 35 recognizes the gamma-peptide associated with these preparations and human placental G-protein oligomers. The antiserum does not recognize Gt gamma. Protease digestion of Gt beta 36 and human placental beta 35 with Staphylococcus aureus V8 protease identified a unique peptide generated from beta 35 which is absent in beta 36 digests.

Antibody Specificity↗
PubMed1987

An elective in primary care internal medicine for students in the preclinical years.

A two-week elective to introduce first- and second-year medical students to primary care internal medicine was developed and evaluated. Course time is divided between conference sessions (25 percent) provided by full-time clinical faculty members and office experience (75 percent) provided by volunteer clinical faculty members (general internists in private practice and in prepaid health plans). Evaluations by the students (n = 58) who took the elective consisted of a questionnaire assessment of the conference session topics, the student's ability to carry out course objectives, and the preceptor's teaching activities. The conference topics were highly rated, with a mean score of 4.1 on a rating scale ranging from 1 (unfavorable) to 5 (favorable). The course objectives and teaching activities were also well rated, with a mean score of 4.1 and 3.9, respectively, on a rating scale ranging from 1 (none) to 5 (outstanding).

Curriculum↗
PubMed1987

Hairy cells possess more interferon receptors than other lymphoid cell types.

To investigate the possible direct effects of alpha-interferon (IFN-alpha) in hairy cell leukemia, IFN-alpha receptor expression by hairy cells (11 cases) was measured by a radiolabeling technique and compared with that of MOLT-4, chronic lymphocytic leukemia (15 cases), and various other leukemic and normal cell types. Purified peripheral blood and splenic hairy cells showed higher levels of receptor expression (approximately 1,000 +/- 200 binding sites/cell; 11 cases tested) than other normal and leukemic cell types. B cells from normal blood and tonsils showed low levels of receptors (approximately 120 +/- 100 binding sites/cell), while a range of B cell leukemias displayed intermediate levels of expression (100-500 sites/cell). In the 15 cases of chronic lymphocytic leukemia tested, 530 +/- 330 binding sites/cell) were demonstrated, the high standard deviation reflecting the fact that one third of cases had receptor levels comparable with those in hairy cell leukemia. Normal and hairy cell leukemia T cells, red cells, and platelets had no demonstrable IFN-receptors. These findings may be relevant to the efficacy of IFN in hairy cell leukemia.

Antigens, Differentiation↗
PubMed1986

G-proteins of fat-cells. Role in hormonal regulation of intracellular inositol 1,4,5-trisphosphate.

Pertussis toxin abolishes hormonal inhibition of adenylate cyclase, hormonal stimulation of inositol 1,4,5-trisphosphate accumulation in rat fat-cells, and catalyses the ADP-ribosylation of two peptides, of Mr 39,000 and 41,000 [Malbon, Rapiejko & Mangano (1985) J. Biol. Chem. 260, 2558-2564]. The 41,000-Mr peptide is the alpha-subunit of the G-protein, referred to as Gi, that is believed to mediate inhibitory control of adenylate cyclase by hormones. The nature of the 39,000-Mr substrate for pertussis toxin was investigated. The fat-cell 39,000-Mr peptide was compared structurally and immunologically with the alpha-subunits of two other G-proteins, Gt isolated from the rod outer segments of bovine retina and Go isolated from bovine brain. After radiolabelling in the presence of pertussis toxin and [32P]NAD+, the electrophoretic mobilities of the fat-cell 39,000-Mr peptide and the alpha-subunits of Go and Gt were nearly identical. Partial proteolysis of these ADP-ribosylated proteins generates peptide patterns that suggest the existence of a high degree of homology between the fat-cell 39,000-Mr peptide and the alpha-subunit of Go. Antisera raised against purified G-proteins and their subunits were used to probe immunoblots of purified Gt, Gi, Go, and fat-cell membrane proteins. Although recognizing the 36,000-Mr beta-subunit band of Gt, Gi, Go and a 36,000-Mr fat-cell peptide, antisera raised against Gt failed to recognize either the 39,000- or the 41,000-Mr peptides of fat-cells or the alpha-subunits of Go and Gi. Antisera raised against the alpha-subunit of Go, in contrast, recognized the 39,000-Mr peptide of rat fat-cells, but not the alpha-subunit of either Gi or Gt. These data establish the identity of Go, in addition to Gi, in fat-cell membranes and suggest the possibility that either Go or Gi alone, or both, may mediate hormonal regulation of adenylate cyclase and phospholipase C.

Adenylate Cyclase Toxin↗
PubMed1986

Sequence-dependent S1 nuclease hypersensitivity of a heteronomous DNA duplex.

Using cloned (dG-dA)n X (dC-dT)n DNA duplexes [GA)n) as models of homopurine-homopyrimidine S1-hypersensitive sites, we show that cleavage of the alternate (non-B, non-Z) DNA structure by S1 nuclease is length-dependent, in both supercoiled and linear forms, which are similar because of the identity of their nicking profiles. However, the length of flanking sequences, the presence of borders, and the DNA topology affect the equilibrium between the alternate structure and B-DNA. The B form of (GA)38 has a 10.4-base pair helical repeat, but the two phosphodiester backbones have different conformations (heteronomous DNA with a dinucleotide repeat unit). Extension experiments reveal that the alternate structure is also heteronomous, in agreement with the nicking patterns generated by S1 and mung bean nucleases and by venom phosphodiesterase. Sensitivity to the latter enzyme at pH 9.0 indicates that the alternate DNA does not appear only in the low pH of the S1 nuclease reaction. Moreover, Hoogsteen G-CH+ base-pairing does not seem to be a prerequisite for the appearance of sensitivity because S1 still recognizes the structure even when all Gs are methylated at N-7. This is consistent with the results of chemical probing of the structure using dimethyl sulfate and diethyl pyrocarbonate at various pH values, which show absence of protection at guanine N-7. However, diethyl pyrocarbonate treatment at low pH results in hyper-reactivity of A residues.

Base Sequence↗
PubMed1986

Purification of the major GTP-binding proteins from human placental membranes.

Using minor modifications of procedures developed to purify GTP-binding proteins (G-proteins) from rabbit liver, we have purified the major G-proteins present in human placental membranes. One, referred to as Gi, is the major substrate for pertussis toxin-catalyzed ADP-ribosylation and has an alpha-subunit of 41,000 daltons, and beta-subunit of 36,000 and 35,000 daltons, and a gamma-subunit of 10,000 daltons. The other protein, referred to as Gp, was identified by its ability to bind guanine nucleotides specifically with high affinity. This activity was resolved from Gs and Gi by the second step of purification (AcA-34 chromatography) and was further purified through heptylamine-Sepharose and hydroxylapatite. The guanine nucleotide-binding site, which can be resolved by high performance liquid chromatography procedures and identified by a photolyzable GTP analogue, is associated with a 21,000-dalton protein (Gp alpha) that copurifies with beta gamma-subunits indistinguishable from the beta gamma-subunits associated with Gs and Gi. This protein represents a potentially novel member of the structurally and functionally homologous family of G-proteins that are transducing elements in the receptor-mediated regulation of a variety of cellular processes.

Adenosine Diphosphate Ribose↗
PubMed1986

The mechanism of action of interferon-alpha (IFN-alpha) in hairy-cell leukaemia; Hu-IFN-alpha 2 receptor expression by hairy cells and other normal and leukaemic cell types.

To investigate the possible direct effects of interferon-alpha (IFN-alpha) in hairy-cell leukaemia, IFN-alpha receptor expression by hairy cells (HCs) (11 cases) was measured by a radiolabelling technique and compared with that of MOLT-4, chronic lymphocytic leukaemia (CLL; 14 cases) and various other leukaemic and normal cell types. Purified peripheral blood (PB) and splenic HCs showed higher levels of receptor expression (approx. 1000 +/- 200 binding sites/cell; 11 cases tested) than other normal and leukaemic cells types. Purified normal PB and tonsil B cells showed low levels of receptors (approx. 120 +/- 100 binding sites/cell), while a range of B-cell leukaemias displayed intermediate levels of expression (approx. 100-500 sites/cell). In the 15 cases of CLL tested, 530 +/- 330 binding sites/cell were demonstrated, the high standard deviation reflecting the fact that approximately one third of cases had receptor levels comparable with those in HCL. Normal and HCL T cells, red cells and platelets had no demonstrable IFN receptors. It is suggested that these findings may be relevant to the efficacy of IFN in hairy-cell leukaemia.

B-Lymphocytes↗
PubMed1986

Effect of context on perception of emotion among psychiatric patients.

The purpose of this research was to examine the extent to which verbal statements of context influence psychiatric patients' perception of photographs of emotion (fear, anger, sadness, and happiness). The major findings showed that, when photographs were paired congruently with context statements, there were significant changes in agreement among subjects on two of the four emotion stimuli. There was significantly less agreement on the meaning of facial expressions when the stimuli for fear, anger, and happiness were accompanied by incongruent verbal statements than when they were viewed alone. These data appear to have implications for practitioners working with this population.

Adult↗