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D L Wong

Publications and source records attributed to D L Wong.

At least 19 recordsLinked to original sources
PubMed1995

Differential activation of the rat phenylethanolamine N-methyltransferase gene by Sp1 and Egr-1.

The rat phenylethanolamine N-methyltransferase (PNMT) gene contains overlapping consensus elements for the Sp1 and Egr-1 transcription factors located at -45 bp and -165 bp in the PNMT promoter. In the present study, we show that Sp1 and Egr-1 can specifically bind to these overlapping elements, that this binding appears to be mutually exclusive, and that binding site occupancy is dependent upon the concentration of each factor and its binding affinity for each site. Egr-1 binds to the -165 bp site with relatively high affinity (IC50 = 14 nM) and to the -45 bp site with relatively low affinity (IC50 = 1360 nM), whereas Sp1 binds to both sites with intermediate affinities (IC50 = 210 and 140 nM, respectively). Consistent with the DNA-binding data, Egr-1 stimulates PNMT promoter activity primarily through interaction with the -165 bp site, while Sp1 stimulates PNMT promoter activity by interacting with both the -45 bp and the -165 bp sites. These results show that Sp1 and Egr-1 are capable of differentially activating PNMT gene expression, thereby suggesting that different stimuli may control the activity of the PNMT gene by selectively regulating Sp1 and/or Egr-1.

Animals↗
PubMed1995

Role of transcription factor Egr-1 in phorbol ester-induced phenylethanolamine N-methyltransferase gene expression.

Transfection of PC12-variant RS1 cells with an Egr-1 expression construct has previously been shown to stimulate phenylethanolamine N-methyltransferase (PNMT) promoter activity, thus suggesting a putative role of Egr-1 as a factor regulating PNMT gene expression. To elucidate the physiological implication of this finding, the effects of phorbol 12-myristate 13-acetate (PMA) on PNMT promoter activity and Egr-1 expression were examined. PMA stimulated luciferase expression in RS1 cells transfected with a rat PNMT promoter-luciferase reporter gene construct, and also elevated both Egr-1 mRNA and Egr-1 protein levels in the untransfected cells. Further study on the concentration dependence of PMA action showed that the stimulation of luciferase expression correlated with the elevation of Egr-1 mRNA level. Finally, the stimulatory action of PMA on luciferase expression was dramatically diminished in the cells transfected with a mutant construct in which the Egr-1 binding site in PNMT promoter was mutated. These findings suggest that PMA-stimulated PNMT gene expression requires the enhancement of Egr-1 expression, thus providing further evidence for the physiological role of Egr-1 in the regulation of PNMT gene expression in the adrenergic cell.

Animals↗
PubMed1995

Laryngeal image analysis following botulinum toxin injections in spasmodic dysphonia.

The injection of botulinum toxin (BT) into laryngeal muscles has proven to be an effective treatment for spasmodic dysphonia (SD), a neurologic disorder characterized by intermittent vocal spasms during speech. BT treatment has reduced abnormal laryngeal muscle hyperactivity in SD patients, when measured by subjective visual rating scales. This paper utilizes images obtained from endoscopic laryngeal video recordings to quantify changes in pre- and post-injection parameters of 17 patients following bilateral BT injections. A previous study, utilizing perceptual, acoustic, and laryngeal aerodynamic measures, showed significant improvements following treatment with BT. In addition, post-injection vocal rest, rather than vocalization, enhanced therapeutic responses. Results of these measures are compared with data from the image analyses and those parameters that proved to be the most useful are highlighted.

Adult↗
PubMed1994

Neural control of dopamine beta-hydroxylase in vivo: acute and chronic effects.

Reserpine treatment was used to examine whether short- and long-term neural stimulation regulates rat adrenal medullary dopamine beta-hydroxylase (DBH, EC 1.14.17.1) through transcriptional activation and to examine the extent of coordinate control of DBH and phenylethanolamine N-methyltransferase (PNMT, EC 2.1.1.28). A single dose of reserpine (10 mg/kg i.p.) elevates DBH mRNA 1.5-fold by 6 h post-injection. Chronic treatment (10 mg/kg i.p., 4 alternate day injections) continues the rise in DBH mRNA, with a peak of 3.4-fold control values after 2 doses of reserpine and a plateau at this level thereafter. Even though DBH mRNA is elevated 6 h after a single injection of reserpine, DBH activity does not change in parallel. A 1.3-fold rise in activity occurs at 24 h post-injection. In contrast, chronic reserpine treatment concomitantly increases DBH activity and mRNA. As observed for DBH mRNA, enzyme activity peaks and plateaus after 2 injections on alternate days. However, the rise in enzymatic activity is less than the rise in mRNA (2.4-fold versus 3.4-fold). Ribosomal loading experiments demonstrate that the DBH mRNA pool is fully utilized for protein synthesis with an apparent decrease in the number of ribosomes loaded per molecule of mRNA. Western analysis and thermal denaturation studies indicate that an altered form of DBH may be expressed. With a single dose of reserpine, the enzyme shows a decline in specific activity while repeated treatment leads to an enzyme with higher specific activity. In both cases, the protein appears to be more stable. Reserpine treatment also markedly elevates adrenal glucocorticoids. A 1.5-fold increment in glucocorticoid receptor mRNA accompanies the corticosteroid rise, with the receptor mRNA peaking at 6 h and remaining at this level thereafter. The up-regulation of glucocorticoid receptor mRNA expression, together with the presence of a putative glucocorticoid response element in the 5' flanking region of the DBH gene, suggests that neural and hormonal regulatory mechanisms may work in concert to control DBH gene transcription. Finally, by comparison to PNMT, activation of DBH appears to require sustained stimulation of the neural axis, since acute changes in mRNA lead to only minor changes in enzyme expression. Similar to PNMT, continuous neural stimulation increases both DBH mRNA and enzymatic activity. However, the discordance in the magnitude of these indices suggests that other regulatory controls may be important in setting the ultimate limits on DBH expression, glucocorticoids perhaps being one such influence.

Animals↗
PubMed1994

Developing concise tables.

When faced with the dilemma of what tables to include in their manuscripts, some authors mistakenly assume the more tables the better. Others admit they put all the tables in, hoping the editor will pick the ones he or she wants. Many of these authors find the manuscripts rejected. Do not assume the editor or reader will weed through your tables or condense them. Instead, spend at least as much, if not more, time developing your tables as you spend editing the text sections. This author with experience in book, article, and research publications describes four guidelines she uses to develop tables for a successful manuscript.

Audiovisual Aids↗
PubMed1994

Molecular analysis and test of linkage between the FMR-1 gene and infantile autism in multiplex families.

Approximately 2%-5% of autistic children show cytogenetic evidence of the fragile X syndrome. This report tests whether infantile autism in multiplex autism families arises from an unusual manifestion of the fragile X syndrome. This could arise either by expansion of the (CGG)n trinucleotide repeat in FMR-1 or from a mutation elsewhere in the gene. We studied 35 families that met stringent criteria for multiplex autism. Amplification of the trinucleotide repeat and analysis of methylation status were performed in 79 autistic children and in 31 of their unaffected siblings, by Southern blot analysis. No examples of amplified repeats were seen in the autistic or control children or in their parents or grandparents. We next examined the hypothesis that there was a mutation elsewhere in the FMR-1 gene, by linkage analysis in 32 of these families. We tested four different dominant models and a recessive model. Linkage to FMR-1 could be excluded (lod score between -24 and -62) in all models by using probes DXS548, FRAXAC1, and FRAXAC2 and the CGG repeat itself. Tests for heterogeneity in this sample were negative, and the occurrence of positive lod scores in this data set could be attributed to chance. Analysis of the data by the affected-sib method also did not show evidence for linkage of any marker to autism. These results enable us to reject the hypothesis that multiplex autism arises from expansion of the (CGG)n trinucleotide repeat in FMR-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Adrenergic expression in the rat adrenal gland: multiple developmental regulatory mechanisms.

Phenylethanolamine N-methyltransferase (PNMT, EC 2.1.1.28) has been used as a marker to examine development of adrenergic expression in the rat adrenal gland and the putative role of glucocorticoids in this process. PNMT enzymatic activity increases 7-10-fold from birth to postnatal day 35. Immunotitration studies show that PNMT protein only increases 4-5-fold during this same time period. Moreover, the slopes from the immunotitration curves decrease with increasing age. Thus, a more active enzyme with lower affinity for the antiserum appears to be present in the older animals. Quantitative solution hybridization shows that PNMT mRNA increases 2.5-fold from birth through postnatal day 11. Thereafter, it declines, and eventually plateaus at values insignificantly different from birth by postnatal day 25. Northern analysis further shows that two forms of PNMT mRNA are expressed. Adrenal corticosterone remains low from birth through postnatal day 11, but then increases nearly 10-fold by adulthood. The lack of concordance between changes in PNMT activity, protein, and mRNA suggests that adrenergic expression is developmentally regulated at multiple levels; the above provides evidence for both transcriptional and post-transcriptional controls, since changes in PNMT mRNA may differ in both magnitude and direction from changes in PNMT activity and protein during the developmental window examined. These developmental regulatory mechanisms may be in part glucocortocoid-mediated, but corticosteroid control of PNMT gene expression does not appear to be the predominant mechanism of control.

Actins↗
PubMed1992

Glucocorticoid regulation of phenylethanolamine N-methyltransferase in vivo.

In vivo, supraphysiological doses of glucocorticoids are required to restore adrenal medullary phenylethanolamine N-methyltransferase (PNMT, E.C. 2.1.1.28) activity after hypophysectomy. However, in vitro, phenylethanolamine N-methyltransferase gene expression appears normally glucocorticoid-responsive. To explore this paradox, rats were given dexamethasone or the type II-specific glucocorticoid RU28362 (1-1000 micrograms/day), and adrenal phenylethanolamine N-methyltransferase activity and mRNA levels were determined. At low doses (1-30 micrograms/day), neither steroid altered mRNA whereas at higher doses (100-1000 micrograms/day), mRNA rose 10- to 20-fold, with dexamethasone approximately 3 times as potent as RU28362. In contrast, enzyme activity fell with low doses of either steroid, consistent with suppression of ACTH and endogenous steroidogenesis. At higher doses of RU28362, enzyme activity remained low and unchanged despite increased mRNA expression, whereas higher doses of dexamethasone progressively restored the enzyme to normal. These findings suggest 1) that glucocorticoid regulation of phenylethanolamine N-methyltransferase activity occurs largely independent of gene expression; 2) that glucocorticoid effects on enzyme activity are primarily indirect, probably through cosubstrate regulation and/or enzyme stabilization; and 3) that these effects are not mediated via a classical (type II) glucocorticoid receptor mechanism, given the high doses of dexamethasone and corticosterone required and the inability of RU28362 to mimic the effects of these less selective steroids.

Animals↗
PubMed1991

Transition from hospital to home for children with complex medical care.

Home care has become a well-accepted option for children with chronic illnesses, such as cancer, who require continued technological care for survival. Components of successful home care include assessment of the child and family for this option, assessment of the community's ability to provide the services the family needs, development of a comprehensive care plan, education of care givers, and ongoing evaluation of the plan. Nurses play a major role in the discharge planning for home care by educating care givers to perform the necessary care, by providing opportunities for care givers to demonstrate competence before assuming total responsibility, and by ensuring that the care givers and the home environment are ready for the child's discharge. Throughout this process, the principles of normalization are applied to provide the child with an optimun home environment. Establishing parent-professional partnerships is crucial to providing family support that empowers family members, especially parents, to assume the responsibilities of caring for their child.

Child↗
PubMed1990

Subunit characterization and primary structure of bovine adrenal medullary dopamine beta-hydroxylase.

Bovine adrenal medullary dopamine beta-hydroxylase was purified by sucrose density sedimentation, gel filtration chromatography, and Concanavalin A-Sepharose 4B affinity chromatography. Three subunits have been identified, of 71, 75, and 78 kd, present at a ratio of 1:2:1. Homogeneous subunits were isolated on denaturing polyacrylamide gels. Endoglycosidase treatment reduced each polypeptide to a 66-kd species, indicating that high and complex mannans account for the major differences in the subunits. The subunits and their 66-kd products cross-react with an anti-native dopamine beta-hydroxylase antiserum, suggesting common antigenic epitopes. Amino acid content analysis shows enrichment in glutamic acid/glutamine, aspartic acid/asparagine, glycine, and leucine, with little cysteine, tyrosine, proline, lysine, and methionine. Two to three nonidentical polypeptides have been identified from cyanogen bromide fragments. Comparison of the bovine peptide sequences to the corresponding cDNA-deduced human sequences show substantial similarity. Many of the species-specific differences in the primary structure represent conservative changes in amino acids or single base pair changes in amino acid codons.

Adrenal Medulla↗
PubMed1990

Primary structure of bovine adrenal phenylethanolamine N-methyltransferase.

Bovine adrenal medullary phenylethanolamine N-methyltransferase (E.C. 2.1.1.28) was sequenced to determine if primary structure or post-translational processing accounts for the charged isozymes. A blocked NH2-terminus precluded amino terminal sequencing. Therefore, cyanogen bromide and tryptic peptide fragments were isolated and subjected to gas phase/gas-liquid phase sequencing. Primary structure was identified for 45% of the protein. At least two polypeptide chains exist with alternative amino acids representing conservative changes or single-base changes in amino acid codons by comparison to the cDNA sequence for the enzyme.

Adrenal Medulla↗
PubMed1988

Catecholamine innervation of the rat hypoglossal nucleus.

The catecholamine innervation of the hypoglossal nucleus (XII) was investigated immunocytochemically by comparing the distribution patterns of tyrosine hydroxylase (TH), dopamine-beta-hydroxylase (DBH) and phenylethanolamine N-methyltransferase (PNMT) in the rat. Numerous TH- and DBH-positive profiles were found throughout XII, while only occasional PNMT immunoreactivity was observed. Significantly, the distribution patterns of TH and DBH immunoreactivity were coextensive with the most intense staining found ventromedially along the caudal half of XII. We conclude, therefore, that the catecholamine innervation of XII is largely noradrenergic, and that motoneurons innervating the genioglossi muscles, the principal protrusors of the tongue, are the primary targets of this input.

Animals↗
PubMed1987

Characterization of the isozymes of bovine adrenal medullary phenylethanolamine N-methyltransferase.

Bovine adrenal medullary phenylethanolamine N-methyltransferase (EC 2.1.1.28) has been purified to apparent homogeneity. The enzymatically active monomer has a relative molecular weight of 30,000 and can be separated into at least four active charged isozymes. These isozymes, designated PNMT-1, PNMT-2, PNMT-3 and PNMT-4, have isoelectric points of 5.1, 5.2, 5.3 and 5.4, respectively. Kinetic parameters have been determined for each isozyme. The Kms for phenylethanolamine range from 11.9 to 45.9 microM; the Kms for S-adenosylmethionine range from 1.13 to 1.47 microM; and the Kis for the competitive inhibitor, S-adenosylhomocysteine, range from 0.12 to 0.22 microM. For isozymes PNMT-1 and PNMT-4, and Kms for S-adenosylhomocysteine are not significantly different. Vmax values for all of the isozymes do not change significantly in the presence of S-adenosylhomocysteine. Treatment of the purified isozymes with various endo- and exoglycosidases does not alter electrophoretic mobility. Hence, carbohydrate substitution must be minimal. No high mannan, complex sugars or terminal N-acetylglucosamine residues are present. The absence of carbohydrate is further supported by the inability of Schiff-periodic acid to stain the protein. Limited thermolysin digests of each isozyme show distinct peptide cleavage products. In conjunction with the kinetic and glycosylation data, this suggests that the isozymes of phenylethanolamine N-methyltransferase may be primary structural variants.

Adrenal Medulla↗