Search PubMed⌕ Search

Biomedical subjects

C Stewart

Publications and source records attributed to C Stewart.

At least 181 records · Page 10Linked to original sources
PubMed1987

Identification of an enhancer-like element upstream from a cell cycle dependent human H4 histone gene.

We have identified a segment of DNA in the region 6,500 nucleotides upstream from a cell-cycle-dependent human H4 histone gene (pF0108A) which exhibits properties of an enhancer element. This distal element is not required for cap site initiation from the F0108A H4 histone gene. When the enhancer element is present in the genome as a stable integrated sequence, either in its natural upstream location or in a construct where the element is moved just upstream from the proximal promoter sequences, a 25-fold increase in the level of human H4 histone RNAs is observed. This increased level of mRNA reflects an increase in the rate of transcription. The enhancer effect is also observed when the distal element is inserted in inverse orientation with respect to this gene. In addition, the far upstream element can increase expression of a prokaryotic chloramphenicol acetyl transferase (CAT) gene under control of the simian virus 40 (SV40) early promotor, indicating that the ability to influence transcription is not confined to the gene with which it is normally associated. The ability of the histone gene distal enhancer element to function in both mouse and human cells indicates that transacting regulatory factors encoded by either the human or murine genome are capable of mediating the functional properties of this element, further supporting the cross-species compatibility of regulatory sequences and molecules that influence transcription of human histone genes.

Acetyltransferases↗
PubMed1987

Acute effects of short-term subcutaneous terbutaline on theophylline disposition.

Theophylline and subcutaneous terbutaline are frequently used concurrently in the management of acute asthma. Recent evidence demonstrating a reduction in theophylline serum concentrations during concomitant oral terbutaline therapy prompted our evaluation of subcutaneous terbutaline's effect on theophylline pharmacokinetics. Using a randomized, placebo controlled, crossover design, the disposition of a single oral theophylline dose (7 mg/kg) was studied in eight healthy, adult males before and after repeated subcutaneous administration of terbutaline (0.25 mg). Two-way analysis of variance revealed no significant difference in elimination rate constant (ke), area under the concentration-time curve (AUC), or apparent oral clearance (CL/F) of theophylline following terbutaline administration. These results indicate that subcutaneous administration of terbutaline does not alter the pharmacokinetics of single, oral doses of theophylline in adults.

Adult↗
PubMed1987

Proximal and distal regulatory elements that influence in vivo expression of a cell cycle-dependent human H4 histone gene.

We have examined the sequences required in vivo to promote transcription of a cell cycle-regulated human H4 histone gene. Deletion mutants of the 5' flanking region were assayed in mouse cells or fused with the chloramphenicol acetyltransferase (CAT) gene for assay in HeLa cells. The functional limits of the regulatory sequences were shown to extend at least 6.5 kilobases (kb) upstream. Sequences sufficient for correctly initiated transcription were found in the 70 base pairs (bp) immediately 5' to the cap site. A proximal element located 200-400 bp upstream increased the level of transcription several times above the basal level, although not to maximal levels. Maximal levels of expression were achieved with 6.5 kb of 5' flanking sequence adjacent to the proximal promoter sequences or when a distal enhancer element with both position- and orientation-independent function was moved proximal to the promoter. Our results indicate that a series of 5' cis-acting sequences are functionally related to the fidelity and level of expression of this human H4 histone gene.

Animals↗
PubMed1987

Definition of the surface antigens of Mycobacterium malmoense and use in studying the etiology of a form of mycobacteriosis.

Mycobacterium malmoense is the latest of a roster of atypical mycobacteria implicated in pulmonary infections. Yet it lacks recognizable phenotypic features to allow its ready identification. Some 23 clinical isolates of M. malmoense were examined for homologous seroagglutination reactions and characteristic surface antigens. One group showed concordant agglutination interreactions and an identical spectrum of glycolipids and are regarded as M. malmoense sensu stricto. The glycolipids are of the newly found, trehalose-containing lipooligosaccharide class. De-O-acylation followed by high-pressure liquid chromatography revealed one major and several minor oligosaccharides. Partial acidic cleavage to release glycosidically linked trehalose, alpha-mannosidase digestion to demonstrate the presence of a non-reducing-end mannobiose, perdeuteriomethylation, partial acid hydrolysis, reduction, and O ethylation, combined with 1H nuclear magnetic resonance and electron impact and fast-atom bombardment mass spectrometry revealed the structure of the major oligosaccharide as alpha-D-Manp-(1----3) -alpha-D-Manp-(1----[2-alpha-L-Rhap-(1--]4--3)-alpha-L-Rh ap- (1----3)-alpha-D-Glcp-(1----1)-alpha-D-Glcp, in which two of the 2-alpha-L-Rhap residues are O methylated at C-3. (Man, mannose; Rha, rhamnose; Glc, glucose; p, pyranosyl). The structures of the minor oligosaccharides were also determined; they differ at the distal nonreducing end. The dominant oligosaccharide was acylated by octanoate, 2-methyleicosanoate, and 2,4-dimethylpentacosanoate to yield the major species-specific surface antigen of M. malmoense, which we regard as the most characteristic feature of the pathogen.

Agglutinins↗
PubMed1986

Insulin pump treatment in insulin-dependent diabetes mellitus. Children, adolescents, and young adults.

Twenty-four children, teenagers, and young adults (8 to 26 years old) with insulin-dependent diabetes mellitus were treated with continuous subcutaneous insulin infusion (CSII). Criteria for using CSII included persistent high glycohemoglobin (GHb) values and/or wide swings in blood glucose values despite arduous efforts to improve glycemia. Thirty percent discontinued CSII. Improvement was significant by three months for GHb and blood glucose values, but plateaued thereafter. Only three patients attained a normal GHb value. No predictors for degree of control were identified. Diabetic ketoacidosis did not occur more frequently with CSII. Electromechanical problems with the devices, patient errors, or local skin problems occurred in 50% of patients, although none produced ketoacidosis or severe hypoglycemia. Dietary noncompliance and decreased intensive home monitoring were contributory factors. Better ways to predict success or failure are needed if normalization or even near-normalization is a goal of CSII in younger patients with insulin-dependent diabetes mellitus followed up in a nonresearch setting.

Adolescent↗
PubMed1986

Spontaneous contrast visualization on the right side of the heart during echocardiography.

Microbubble contrast visualization within the right heart is almost always due to intravenous injections containing microbubbles. In the absence of immediate administration of agitated solutions, several other mechanisms for the occurrence of echo contrast spontaneously in the cardiovascular system have been postulated. Often overlooked as a source of contrast are microbubbles from remotely injected solutions that persist in the circulation because of markedly delayed clearance. Two patients were observed with apparently spontaneous contrast detected in the right heart chambers, both of whom had congestive heart failure, tricuspid regurgitation, and pulmonary hypertension. Regardless of the exact mechanism involved, the finding of this phenomenon reflects the presence of right heart failure and a low flow state.

Aged↗
PubMed1985

The prevalence of retained testes in Dunedin.

A cohort of approximately 500 boys was screened for retained testes at ages five and seven years and when the boys were aged three, five, seven and nine years, their parents were questioned about hospitalisation for surgery. Orchidopexy for retained testes had been performed on 15 of the 536 boys (2.8%) while one other had orchidopexy for high retractile testes (0.2%). Eighty-one percent of this surgery was performed between the seventh and ninth years of age.

Child↗
PubMed1985

Spectral and other physicochemical properties of submicron powders of hematite (alpha-Fe2O3), maghemite (gamma-Fe2O3), magnetite (Fe3O4), goethite (alpha-FeOOH), and lepidocrocite (gamma-FeOOH).

Spectral and other physicochemical properties were determined for a suite of submicron powders of hematite (alpha-Fe2O3), maghemite (gamma-Fe2O3), magnetite (Fe3O4), goethite (alpha-FeOOH), and lepidocrocite (gamma-FeOOH). The spectral reflectivity measurements were made between 0.35 and 2.20 micrograms over the temperature interval between about -110 degrees and 20 degrees C. Other physicochemical properties determined were mean particle diameter, particle shape, chemical composition, crystallographic phase, magnetic properties, and Mossbauer properties. Only the magnetite powders have significant departures from the stoichiometric phase; they are actually cation-deficient magnetites having down to about 18.0 wt % FeO as compared with 31.0 wt % FeO for stoichiometric magnetite. A structured absorption edge due to crystal field transitions and extending from weak absorption in the near-IR to intense absorption in the near-UV is characteristic of the ferric oxides and oxyhydroxides and is responsible for their intense color. Particularly for hematite, the number and position of the spectral features are consistent with significant splitting of the degenerate cubic levels by noncubic components of the crystal field. The position of the crystal-field band at lowest energy, assigned to the envelope of the components of the split cubic 4T1 level, is near 0.86, 0.91, 0.92, and 0.98 microgram at room temperature for hematite, goethite, maghemite, and lepidocrocite, respectively. Comparison with Mossbauer data suggests covalent character increases sequentially through the aforementioned series. The positions of the spectra features are relatively independent of temperature down to about -110 degrees C. The maximum shifts observed were on the order of about 0.02 microgram shortward for the ferric oxyhydroxides. Variations in the magnitude of the reflectivity of the hematite powders as a function of mean particle diameter are consistent with scattering theory. The absorption strength of the crystal-field bands increases with increasing mean particle diameter over the range 0.1-0.8 micrometer; visually this corresponds to a change in color from orange to deep purple. The position of the split cubic 4T1 band shifts longward by about 0.02 micrometer with decreasing mean particle diameter over the same range; this trend is consistent with wavelength-dependent scattering. The cation-deficient magnetite powders are very strong absorbers throughout the near-UV, visible and near-IR; their spectral properties are independent of temperature between about -110 and 20 degrees C.

Earth, Planet↗
PubMed1985

Discrepancy in ER levels of breast carcinoma in biopsy vs mastectomy specimens.

The presence of estrogen receptors (ER) in breast tumors has been used by many as the major indicator for hormonal treatment of breast cancer. However, multiple factors have been shown to be involved in determining the hormone dependence of breast cancer. This paper reports another factor that influences the accuracy of ER determination. From January 1977 through December 1983 fifty-eight (58) of these patients had ER determination of both biopsy and mastectomy specimens. Of the 31 patients that remained ER positive in mastectomy specimen, 13 had significantly lower ER levels (by at least 50%) from the mastectomy specimens. These findings indicate that ER status is greatly influenced by the source of the specimen.

Adult↗
PubMed1985

Induction of cellular thymidine kinase occurs at the mRNA level.

The thymidine kinase (TK) gene has been isolated from human genomic DNA. The gene was passaged twice by transfection of LTK- cells with human chromosomal DNA, and genomic libraries were made in lambda Charon 30 from a second-round TK+ transformant. When the library was screened with a human Alu probe, seven overlapping lambda clones from the human TK locus were obtained. None of the seven contained a functional TK gene as judged by transfection analysis, but several combinations of clones gave rise to TK+ colonies when cotransfected into TK- cells. A functional cDNA clone encoding the human TK gene has also been isolated. Using this cDNA clone as a probe in restriction enzyme/blot hybridization analyses, we have mapped the coding sequences and direction of transcription of the gene. We have also used a single-copy subclone from within the coding region to monitor steady-state levels of TK mRNA in serum-stimulated and simian virus 40-infected simian CV1 tissue culture cells. Our results indicate that the previously reported increase in TK enzyme levels seen after either treatment is paralleled by an equivalent increase in the steady-state levels of TK mRNA. In the case of simian virus 40-infected cells, the induction was delayed by 8 to 12 h, which is the length of time after infection required for early viral protein synthesis. In both cases, induction of TK mRNA coincides with the onset of DNA synthesis, but virally infected cells ultimately accumulate more TK mRNA than do serum-stimulated cells.

Animals↗
PubMed1984

Murine gamma interferon activates the release of a macrophage-derived Ia-inducing factor that transfers Ia inductive capacity.

In this report we demonstrate that when the murine macrophage tumor cell line P- 388D1 is incubated for 48-72 h with either concanavalin A-stimulated rat spleen cell supernatant or cloned murine immune interferon (IFN-gamma), the cultured cells release a cell-free factor activity that in turn induces the cell surface expression of Ia antigen on the murine monocyte cell line WEHI-3. This IFN-gamma-stimulated, Ia-inducing activity cannot be blocked with an anti-IFN-gamma heteroantiserum that does block the induction of Ia expression on WEHI-3 by both cloned murine IFN-gamma and rat Con A supernatant. The Ia-inducing factor ( IaIF ) generated from P- 388D1 after stimulation by IFN-gamma does not demonstrate any antiviral activity. The P- 388D1 -derived IaIF is not shed plasma membrane Ia glycoprotein molecules, as demonstrated by the inability of the active component to bind specifically to an anti-I-Ad affinity column or to a protein A column after the active supernatant is first treated with an excess of anti-I-E/Cd,k monoclonal antibody.

Animals↗
PubMed1984

Administration of activated charcoal for the treatment of lantana poisoning of sheep and cattle.

The use of activated charcoal for treating lantana poisoning was investigated. When 500 g of activated charcoal was given orally with toxic Lantana camara, it protected sheep against intoxication. Administration to sheep of 500 g of activated charcoal in 4 1 of electrolyte solution orally 6 days after the onset of lantana poisoning and then 4 1 of electrolyte solution the next day, was followed by recovery from the intoxication. Mortality was significantly higher in intoxicated sheep given only the electrolyte solution and in untreated sheep. Six cows with naturally occurring lantana poisoning were treated with 2-2.5 kg of charcoal in 20-30 1 of electrolyte solution given by stomach tube and all the animals recovered. It is recommended that sheep with lantana poisoning be treated orally with 500 g of activated charcoal in 4 1 of electrolyte solution, and that cattle be given 2 kg of charcoal in 20 1 of electrolyte solution. Supportive treatment for photosensitization and dehydration may also be required.

Animals↗
PubMed1984

The effect of asymmetrically focused attention upon subsequent ear differences in dichotic listening.

In a series of four experiments, normal right-handed adults engaged in dichotic listening with free-report instructions after having completed a selective listening task. The usual right-ear advantage (REA) for dichotic digit names was altered according to the ear previously monitored. Most notably, the REA was absent among subjects who had monitored the left ear. Additional experiments showed that the "priming bias" is material-specific; it did not occur if consonant-vowel nonsense syllables (CV's) were substituted for digit names in either the selective listening task or the subsequent free-report test. The findings help clarify the nature of one of the attentional mechanisms that influence auditory laterality.

Adolescent↗
PubMed1984

Platelet and fibroblast monoamine oxidase in alcoholism.

Monoamine oxidase (MAO) activity has been reported to be low in platelets (MAO B) and brain (MAO A and B) of some patients with alcoholism compared to control subjects. Whether the decreased platelet MAO activity found in alcoholism is secondary to the effect of alcohol or exists before alcohol abuse is not clear. The hypothesis that altered MAO A activity is determined by an abnormality in the genetic regulation of the enzyme can be tested by measuring MAO A activity in human fibroblasts cultured under controlled conditions. We first studied the kinetic parameters of platelet MAO B activity in patients hospitalized for treatment of alcoholism. Vmax was 38% lower in the patients (n = 14) than in normal controls (n = 22), but the enzyme affinity (Km) for the substrate tyramine was unchanged. Patients with the five lowest levels of platelet MAO activity had MAO activity measured from fibroblasts cultured from skin punch biopsies. Their fibroblast MAO activity was within the normal range, showing a dissociation between platelet MAO B and fibroblast MAO A activities and suggesting that MAO A activity is not low for genetic reasons in alcoholic subjects who do have low platelet MAO B activity.

Alcoholism↗
PubMed1984

Frostbite.

Frostbite can cause loss of life and limbs. Proper treatment and follow-up care are essential in reducing morbidity and mortality. Management of the frostbite patient consists of three stages. Initial care includes protection of the extremity from trauma or partial thawing. The second stage consists of rapid rewarming in a whirlpool bath containing hot water, with continued protection of the tissues. The third stage is long-term care of the affected body parts.

Adolescent↗