Excitation hot-electron spectroscopy.
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Journal Article↗
Biomedical subjects
W Chang
Publications and source records attributed to W Chang.
Structure of the human smooth muscle alpha-actin gene. Analysis of a cDNA and 5' upstream region.
The structures of a cDNA and the 5' upstream region of the human smooth muscle alpha-actin gene have been characterized. Transcriptional start sites and the non-coding first exon were mapped by primer extension analysis and by comparing cDNA and genomic sequences. The deduced human smooth muscle alpha-actin protein sequence is identical to the corresponding bovine protein sequence, and thus confirms that the previously determined human genomic sequence contained a mutation at codon 312. Human smooth muscle cells express only a single, 1.4-kilobase smooth muscle alpha-actin transcript. 5' Noncoding sequences that have the greatest similarity to the chicken gene are located in five noncontiguous segments, extending from approximately 250 base pairs upstream of the cap site through the first exon. Conserved sequences encompass a region required for expression and tissue-specific regulation of chicken smooth muscle alpha-actin and therefore are probably also important for expression of the human gene.
Actins↗
Tumorigenic poxviruses: characterization of the expression of an epidermal growth factor related gene in Shope fibroma virus.
The transcription and translation of an epidermal growth factor (EGF) related gene in the Leporipoxvirus Shope fibroma virus (SFV), termed the Shope fibroma growth factor (SFGF), have been characterized. Three early RNA transcripts complimentary to an anti-SFGF oligonucleotide were detected by Northern blot analysis, while no late transcripts were expressed. The activity of the SFGF early promoter was measured using a transient gene expression assay in SFV-infected cells using the bacterial choloramphenicol acetyltransferase as a reporter gene. Deletion analysis showed that the functional SFGF promoter domain is an AT-rich sequence contained within 30 bp of the major transcriptional initiation site as is typical of early poxvirus promoters. An intracellular form of the SFGF gene product was immunoprecipitated from infected lysates using rabbit antisera raised against a synthetic SFGF (amino acids 26-80). A 16-kDa product was detected, while in cells infected in the presence of tunicamycin, the immunoprecipitated product had a mobility on SDS-polyacrylamide gels of approximately 6 kDa, indicating that the SFGF gene product is extensively post-transcriptionally modified. The intracellular 16-kDa form can be pulse-chased to a 14-kDa form but the secreted form of SFGF could not be detected in the medium using this anti-peptide antiserum.
Base Sequence↗
A 3-D anthropomorphic brain phantom for ECT applications.
A three-dimensional (3-D) anthropomorphic brain phantom was developed for ECT (emission computed tomography) applications. This phantom is made up of a stack of interlaced plates as an insert in a water tank containing radioactive solution. The thickness of the plates in the stack is chosen to create the desired spatial frequency content and object contrast between simulated grey and white matter regions for tracers commonly used to study regional blood flow or metabolism. The transverse, sagittal, and coronal SPECT images acquired with a rotating camera system show a realistic simulation of the grey matter distribution in a human brain.
Brain↗
In vivo SPECT imaging of CNS D-2 dopamine receptors: initial studies with iodine-123-IBZM in humans.
Iodobenzamide (IBZM) is a D-2 dopamine receptor antagonist. In this paper the results of Phase I clinical studies of iodine-123-(123I)IBZM in humans are reported. Preliminary imaging studies, both planar and single-photon emission tomography (SPECT), of no-carrier added [123I]IBZM in humans show specific localization in the basal ganglia of the brain. At 2 hr after an i.v. injection, the brain uptake was 3.72% of the dose, and at 20 hr later the uptake diminished to 0.7%. Radiation dosimetry calculation indicated that the radiation dose to the brain was minimum, 0.039 rad/mCi, while the large intestine wall received the highest dose, 0.28 mrad/mCi. The radiation dosimetry and pharmacology data suggest that this agent is safe for human use.
Adult↗
Effects of vasoactive intestinal contractor (VIC) and endothelin on intracellular calcium level in neuroblastoma NG108-15 cells.
Effects on [Ca2+]i levels of endothelin-l (ET) and vasoactive intestinal contractor peptide (VIC), which is a novel member of the endothelin family, were examined in fura 2-loaded neuroblastoma NG108-15 cells. VIC was found to be a very effective stimulus for intracellular Ca2+ mobilization and to be more potent than ET. Intracellular calcium response to sequential addition of two stimulants exhibited the homologous desensitization of either ET or VIC, but no heterologous desensitization between ET and VIC. This indicates evidence suggesting that these two peptides act through distinct receptors.
Calcium↗
Distribution of [3H]dihydrotetrabenazine binding in bovine striatal subsynaptic fractions: enrichment of higher affinity binding in a synaptic vesicle fraction.
[3H]Dihydrotetrabenazine bound to a single class of binding sites in bovine striatal synaptic vesicles with an apparent dissociation constant of 3-9 nM. This is comparable to the inhibitory potency of dihydrotetrabenazine in catecholamine transport assays. In contrast to these results, [3H]dihydrotetrabenazine bound to at least two classes of sites in all other subsynaptic fractions investigated. The higher affinity class of sites was comparable in affinity to that of synaptic vesicles, whereas the lower affinity sites exhibited an apparent dissociation constant of 95-400 nM. Higher affinity sites were most abundant in the synaptic vesicle fraction, and little higher affinity binding was observed in mitochondrial and myelin fractions, or in highly purified synaptic plasma membranes. Lower affinity binding was not enriched in any subsynaptic fraction and was the only class of binding sites detected in homogenates of liver and diaphragm. The distribution of the presynaptic vesicle marker synaptophysin corresponded with that of higher affinity but not lower affinity binding. These results are consistent with the expectation that the higher affinity sites are associated primarily with synaptic vesicles and other neuronal entities that are in communication with these organelles.
Animals↗
Characterization of vaccinia virus growth factor biosynthetic pathway with an antipeptide antiserum.
A synthetic peptide derived from vaccinia virus growth factor (VGF) was used as an immunogen to prepare antiserum able to immunoprecipitate native VGF from both vaccinia virus-infected cell lysate and cell-free medium. Pulse-chase, tunicamycin treatment, and carbohydrate trimming experiments revealed that VGF is synthesized as a 19-kilodalton (kDa) precursor which is rapidly modified to a high-mannose-type 22-kDa protein. This cell-associated form is further processed into a 25-kDa polypeptide which, after proteolytic cleavage, releases the mature VGF into the medium as a 22-kDa glycoprotein.
Amino Acid Sequence↗
Vitamin E and selenium levels of premature infants with severe respiratory distress syndrome and bronchopulmonary dysplasia.
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Bronchopulmonary Dysplasia↗
Ganglion cysts of the anterior cruciate ligament. A case report.
Ganglion cysts of the cruciate ligaments of the knee are rare. A case is presented of a ganglion cyst of the anterior cruciate ligament diagnosed arthroscopically.
Adult↗
[Determination of diameters (vertical, horizontal), areas of optic cup, optic disk and neuroretinal area of normal persons].
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Biometry↗
High-efficiency gene transfer and expression in normal human hematopoietic cells with retrovirus vectors.
Retroviral vectors containing the selectable bacterial gene for G418 resistance (neo) were used to demonstrate gene transfer into primary human bone-marrow progenitor cells. To obtain populations of cells in which a high proportion of cells were expressing the neo gene, several important modifications were made to earlier procedures. Cells from normal donors were infected in vitro, were exposed to high concentrations of G418 for two days in liquid culture to enrich for cells expressing the neo gene, and were plated in semisolid medium. Gene transfer and expression were detected in colonies arising from progenitors of granulocyte-macrophage and erythroid lineages. Survival curves indicated that a high proportion of progenitor cells, approaching 100%, were G418 resistant. Furthermore, addition of growth factors contained in 5637-conditioned medium to the bone marrow improved the recovery of G418-resistant progenitors twofold to threefold. In addition to these biological measurements of gene expression in progenitor cells, significant levels of neo-specific RNA, similar to the levels of RNA expression in the virus-producing fibroblast cell line, were detected in the bone marrow cells after preselection. These results demonstrate that retrovirus vectors can be used successfully to transfer genes at high efficiency into progenitor cells in the human blood-forming system.
Drug Resistance, Microbial↗
New methods of examining gamma camera collimators.
New methods are proposed and described to examine the quality of gamma camera collimators in two special performance categories, namely, uniformity in regional efficiency and regional variations in channel tilt. These two performances are critical areas for SPECT imaging. Results obtained from experimental and commercial collimators illustrate the variability seen for these performance characteristics in currently available collimators.
Quality Control↗
Light-stimulated protein movement in rod photoreceptor cells of the rat retina.
We examined the intracellular distribution of three proteins involved in the cyclic GMP cascade of visual transduction; cGMP phosphodiesterase, the alpha-subunit of G-protein and arrestin. In adult rats, light-induced changes in the amounts of G and arrestin in the photoreceptor cell outer segments were observed both by polyacrylamide gel analysis of purified ROS and by immunocytochemical localization on retinal sections. In dark conditions, G was concentrated in the outer segments of photoreceptor cells while in the light G alpha was seen in the inner segments and the outer nuclear layer. Arrestin had the opposite distribution, appearing in the inner segments and outer nuclear layer under dark conditions and in the ROS under light conditions. In contrast, PDE, the enzyme which is activated by G and inhibited by arrestin showed no light-stimulated movement. In both light- and dark-adapted retinas, PDE was localized primarily in the outer segments of the photoreceptor cells.
3',5'-Cyclic-GMP Phosphodiesterases↗
The genome of Shope fibroma virus, a tumorigenic poxvirus, contains a growth factor gene with sequence similarity to those encoding epidermal growth factor and transforming growth factor alpha.
Degenerate oligonucleotide probes corresponding to a highly conserved region common to epidermal growth factor, transforming growth factor alpha, and vaccinia growth factor were used to identify a novel growth factor gene in the Shope fibroma virus genome. Sequence analysis indicates that the Shope fibroma growth factor is a distinct new member of this family of growth factors.
Amino Acid Sequence↗
Identification of the binding subunit of the D1-dopamine receptor by photoaffinity crosslinking.
The D1-dopamine receptor from rat striatum has been successfully identified by photoaffinity crosslinking using a newly synthesized radioiodinated derivative of the selective D1-antagonist SCH-23390. This compound, (R,S)-5-(3'-aminophenyl)-8-chloro-2,3,4,5-tetrahydro-3-methyl-[1H]-3- benzazepin-7-ol(SCH-38548), has been radioiodinated by a chloramine T procedure yielding three radioiodinated products. One of these separated congeners (with Rf = 0.35 on thin layer chromatography; CH2Cl2/MeOH/triethylamine; 82.5:17.5:0.01) binds reversibly to rat striatal membranes with high affinity (KD approximately equal to 200 pM), appropriate stereoselectivity, and D1-dopaminergic specificity. [125I]SCH-38548 can be covalently incorporated into a peptide of Mr approximately equal to 72,000 using the heterobifunctional crosslinking reagent N-succinimidyl-6-(4'-azido-2'-nitrophenylamino)hexanoate. Covalent incorporation of [125I]SCH-38548 into the Mr approximately equal to 72,000 peptide can be blocked by dopaminergic agents with D1-dopaminergic specificity (for agonists: SKF-38393 greater than apomorphine greater than dopamine; for antagonists: SCH-23390 much much greater than, SCH-23388 and cis-flupentixol much much greater than trans-flupentixol). The D1-dopaminergic selectivity and specificity of the labeling were further demonstrated by the fact that other antagonists such as domperidone, ketanserin, phentolamine, and alprenolol did not compete for the covalent labeling of the Mr approximately equal to 72,000 peptide. These results indicate that the ligand-binding subunit of the D1-dopamine receptor resides on peptide distinct from that of the D2-dopamine receptor (Mr = 94,000). This new radioligand should be useful in the molecular characterization of the D1-dopaminergic receptor from various sources.
Affinity Labels↗
Measurement of left ventricular mass in vivo using gated nuclear magnetic resonance imaging.
Alterations of left ventricular mass occur in a variety of congenital and acquired heart diseases. In vivo determination of left ventricular mass, using several different techniques, has been previously reported. Problems inherent in some previous methods include the use of ionizing radiation, complicated geometric assumptions and invasive techniques. We tested the ability of gated nuclear magnetic resonance imaging to determine in vivo left ventricular mass in animals. By studying both dogs (n = 9) and cats (n = 2) of various sizes, a broad range of left ventricular mass (7 to 133 g) was examined. With a 0.5 tesla superconducting nuclear magnetic resonance imaging system the left ventricle was imaged in the transaxial plane and multiple adjacent 10 mm thick slices were obtained. Endocardial and epicardial edges were manually traced in each computer-displayed image. The wall area of each image was determined by computer and the areas were summed and multiplied by the slice thickness and the specific gravity of muscle, providing calculated left ventricular mass. Calculated left ventricular mass was compared with actual postmortem left ventricular mass using linear regression analysis. An excellent relation between calculated and actual mass was found (r = 0.95; SEE = 13.1 g; regression equation: magnetic resonance mass = 0.95 X actual mass + 14.8 g). Intraobserver and interobserver reproducibility were also excellent (r = 0.99). Thus, gated nuclear magnetic resonance imaging can accurately determine in vivo left ventricular mass in anesthetized animals.
Animals↗
The giant R wave of acute myocardial infarction.
The common clinical electrocardiographic criteria for diagnosis of acute transmural myocardial infarction include ST segment elevation and tall, upright T waves, but do not include changes in QRS morphology. The purpose of this study was to show that development of a 50% or greater increase in R wave amplitude, the giant R wave, in patients with acute transmural myocardial infarction occurs, and also to characterize changes in QRS morphology which may aid the ECG diagnosis of acute transmural myocardial infarction. Over the past 6 years, 36 patients with an increase in R wave amplitude during acute transmural myocardial infarction were identified at the Strong Memorial Hospital Coronary Care Unit. A significant increase in R wave height (0.33 +/- 0.10 to 0.97 +/- 0.08 mV, p less than 0.05), width (0.03 +/- 0.00 to 0.08 +/- 0.01, p less than 0.05) and area (0.01 +/- 0.00 to 0.05 +/- 0.01 mV-msec, p less than 0.05) appeared in the same ECG lead demonstrating ST segment elevation and tall T waves during the acute phase of transmural myocardial infarction. Patients with diaphragmatic myocardial infarction showed a significant (p less than 0.05) rightward QRS frontal plane axis shift and patients with anterior wall myocardial infarctions developed an anterior QRS axis shift in the horizontal plane during occurrence of the giant R wave. We conclude from this preliminary study that the giant R wave may be observed during acute transmural myocardial infarction and may in part be caused by local intramyocardial conduction delay in acutely ischemic tissue as supported by an increase in the R wave width along with shifts in the frontal and horizontal plane QRS axis toward the area of acute ischemia. The giant R wave occurs in conjunction with ST segment elevation and tall T waves and may aid the ECG diagnosis of acute transmural myocardial infarction.
Creatine Kinase↗