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Biomedical subjects

L S Wright

Publications and source records attributed to L S Wright.

At least 37 records · Page 2Linked to original sources
PubMed1989

Childhood victimization: desensitization effects in the later lifespan.

The hypothesis tested in this study was that young adults who report having been abused by parents or guardians as children would report less concern when confronted with hypothetical situations similar to the type of abuse they had reportedly experienced during childhood. In our study of nonclinical adults those who reported childhood victimization experiences showed diminished concern toward the specific kind of abuse situation encountered earlier in their lifespan.

Adolescent↗
PubMed1988

Identification of glutathione S-transferase as a substrate and glutathione as an inhibitor of in vitro calmodulin-stimulated protein methylation in rat liver cytosol.

This report describes the isolation of the major calmodulin-stimulated methyl acceptor protein of adult rat liver cytosol. This Mr 29,000 methyl acceptor protein (MeAP29) has been purified to apparent homogeneity using ammonium sulfate precipitation and chromatography on DEAE-cellulose, phosphocellulose, hydroxylapatite and Sephadex G-75. Affinity chromatography on glutathione-Sepharose and assays of enzyme activity indicate that MeAP29 is a member of the glutathione S-transferase family. We further show that glutathione can act as an inhibitor of calmodulin-stimulated in vitro methylation of MeAP29 and that MeAP29 methylation is enhanced in non-dialyzed liver cytosol from rats with lowered glutathione levels.

Animals↗
PubMed1987

Variables related to pro-choice attitudes among undergraduates.

Pro-choice attitudes among undergraduates were assessed to determine the extent of anti-abortion sentiments during President Reagan's first term in office, which was marked by his support of the anti-abortion issue as well as by increased media coverage of the right-to-life movement. Self-administered questionnaires were completed by 840 participants enrolled in introductory psychology classes at a university in central Texas during the week prior to the presidential election of 1984. Students were asked if they would approve or disapprove of abortion under four different circumstances. Results indicated that the majority of both males and females were in favor of allowing abortion under all four conditions.

Abortion, Legal↗
PubMed1986

Calmodulin N-methyltransferase. Partial purification and characterization.

The distribution, properties, and substrate specificity of S-adenosylmethionine:calmodulin (lysine) N-methyltransferse (EC 2.1.1.60, calmodulin N-methyltransferase) of the rat have been studied. This enzyme is cytosolic and is found at high levels in tissues with high levels of calmodulin and at low levels in tissues with little calmodulin. In liver, heart, and skeletal muscle, which have low levels of calmodulin and very low calmodulin N-methyltransferase activity (a low ratio of calmodulin N-methyltransferase to calmodulin), calmodulin was found to be incompletely methylated, as judged by its ability to act as a substrate for purified calmodulin N-methyltransferase. Calmodulin N-methyltransferase was purified 470-fold with a 33% yield from rat testis cytosol, using ammonium sulfate precipitation and chromatography on DEAE-cellulose, CM-Sepharose, and Sephadex G-100. At pH 7.4, calmodulin N-methyltransferase did not bind to DEAE-cellulose, but bound strongly to CM-Sepharose. The enzyme eluted from Sephadex G-100 with an apparent molecular weight of 55,000. Purified calmodulin N-methyltransferase was incubated with extracts of rat tissues, and [methyl-3H]AdoMet and methylated proteins were resolved by electrophoresis in an attempt to discover substances other than calmodulin, but this enzyme only catalyzed the methylation of calmodulin, indicating a high degree of substrate specificity. Conditions were established for the in vitro preparative methylation of des(methyl)-calmodulin from Dictyostelium discoideum. Three moles of methyl/mol of calmodulin were incorporated into lysine 115 of des(methyl)calmodulin, resulting in the formation of 1 mol of trimethyllysine at the site normally methylated in calmodulins from most species. Activation of cyclic nucleotide phosphodiesterase by des(methyl)calmodulin was indistinguishable from activation by in vitro methylated or sham methylated Dictyostelium calmodulin, indicating that methylation does not affect the ability of calmodulin to activate this enzyme.

Amino Acids↗
PubMed1986

Posttranslational modification of calmodulin in rat brain and pituitary.

The posttranslational modification of calmodulin has been studied in six brain regions and the anterior pituitary. Carboxylmethylation, calmodulin converting enzyme, and calmodulin (lysine) N-methyltransferase activities were determined. Incubation of calmodulin with cytosolic extracts of these tissues in the presence of the methyl donor [methyl-3H]-S-adenosyl-L-methionine and identification of labeled proteins by gel electrophoresis and fluorography indicated that calmodulin is a substrate for protein carboxylmethyltransferase in all tissues tested. In hippocampus, caudate nucleus, cerebral cortex, and anterior pituitary, but not in cerebellum, superior colliculus, brainstem, or diencephalon, a second methylated protein was found when calmodulin was added to incubation mixtures. This protein was shown to be identical to the previously described product of calmodulin converting enzyme. Converted calmodulin was isolated by fast protein liquid chromatography and shown to be des(Lys)calmodulin, lacking the carboxy terminal lysine residue of calmodulin. The anterior pituitary had by far the highest levels of calmodulin converting enzyme; this enzyme, in turn, was identified as a cobalt-stimulated carboxylpeptidase B. In contrast to the regional differences in these parameters, the levels of calmodulin (lysine) N-methyltransferase did not differ greatly among brain regions, although regional differences in the activity of this enzyme were statistically significant.

Amino Acids↗
PubMed1985

Calmodulin plus cyclic AMP-dependent phosphorylation of a Mr 22,000 pituitary protein.

Protein phosphorylation was examined in cytosolic extracts of adult rat anterior pituitary. In the presence of both cyclic AMP and calmodulin, the phosphorylation of a Mr 22,000 protein was markedly stimulated. Cyclic AMP and calmodulin must both be present in order for this effect to be observed; cyclic GMP does not substitute for cyclic AMP, and the effect is abolished by either trifluoperazine or the heat-stable inhibitor of cyclic AMP-dependent protein kinase. Two-dimensional isoelectric focusing sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicates that there are three molecular species of the Mr 22,000 phosphoprotein, with pI values ranging from 6.8 to 8.1. Phosphorylation of this protein is maximally stimulated by 5 microM cyclic AMP and 5.7 microM calmodulin. The effect of cyclic AMP plus calmodulin is enhanced by preincubation and requires a divalent cation; maximal phosphorylation takes place at 100 microM Mn2+, although higher concentrations of Mg2+ and Co2+ support an equivalent degree of phosphorylation. Cyclic AMP plus calmodulin-dependent protein phosphorylation was not detected in other rat tissues surveyed, including brain, testes, adrenal, kidney, liver, spleen, skeletal muscle, pineal, or posterior pituitary. These results help to explain the previous findings of Brattin and Portanova (Brattin, W.J., Jr., and Portanova, R. (1981) Mol. Cell. Endocr. 23, 77-90) of in vivo but not in vitro phosphorylation of three Mr 20,000 anterior pituitary proteins and indicate a possible point of convergence for calcium and cyclic AMP actions in the anterior pituitary.

Animals↗
PubMed1985

Calmodulin-stimulated protein methylation in rat liver cytosol.

The in vitro methylation of three liver cytosolic proteins was found to be selectively stimulated by calmodulin. This effect was also seen, although to a much smaller degree, in kidney and lung, but not in testes, brain, or spleen. The three methylated proteins affected by calmodulin have apparent Mr = 29,000, 32,000, and 45,000. The stimulation of methylation by calmodulin was greatest for the Mr 29,000 protein; there was an equal degree of methylation of the other two proteins. Dialysis of liver cytosolic fractions also stimulated the methylation of these proteins; the methylation of the Mr 32,000 and 45,000 proteins was stimulated to a greater extent by dialysis than by calmodulin. The degree of stimulation of methylation of the Mr 29,000 protein by calmodulin and dialysis was equivalent, but the addition of calmodulin to dialyzed liver cytosolic fractions gave additive effects on the stimulation of methylation of the Mr 29,000 protein, but not of either the Mr 32,000 or 45,000 proteins. Troponin C stimulated the methylation of the Mr 29,000 protein, but not the Mr 32,000 or 45,000 proteins, whereas parvalbumin stimulated methylation of the Mr 32,000 protein, but not the Mr 29,000 or 45,000 proteins. The effects of calmodulin and dialysis on protein methylation are cation-dependent and substrate-specific; methylation of the Mr 29,000 was supported by Mn2+, Ca2+, and Co2+, and to a lesser degree by Mg2+, Ni2+, and Zn2+. Methylation of the Mr 32,000 protein was supported only by Mn2+ and Mg2+ and methylation of the Mr 45,000 protein by Mn2+, Mg2+, Ca2+, Ni2+, and Zn2+, and to a much smaller extent by Fe2+. In extracts of fetal liver, stimulation of protein methylation by calmodulin or dialysis was restricted to the Mr 45,000 protein. In regenerating liver, stimulation of the methylation of all three proteins was observed, but the stimulation provided by dialysis plus calmodulin was much less than that observed in preparations from intact adult liver, suggesting a possible negative correlation between the rate of cell division and calmodulin-dependent methylation of these hepatic proteins. These results are consistent with the presence in liver of a minimum of three distinct N-methyltransferases and a dialyzable inhibitor which antagonizes calmodulin-dependent protein methylation.

Animals↗
PubMed1985

Suicidal thoughts and their relationship to family stress and personal problems among high school seniors and college undergraduates.

This study investigated the incidence of serious suicidal thoughts (ST's) among 207 high school seniors and 901 college students, and the relationship between ST's and family stress, drinking and drug-abuse problems, and delinquency in these groups. Over 10% of the high school and over 6% of the college students reported ST's. Those considering suicide attempts in both groups were more likely than their classmates to view their parents as having many conflicts with each other, to think of their relationship with their father as poor, to see at least one of their parents as either angry or depressed much of the time, and to perceive themselves as having a drinking or drug-abuse problem. These findings support the call for comprehensive counseling programs at both the high school and college levels.

Adolescent↗
PubMed1985

High school polydrug users and abusers.

Among 433 high school seniors, 12% were determined to be either polydrug users or abusers. In comparison to the non-polydrug users, polydrug users and abusers were significantly more likely to indicate: (1) physical abuse by and many conflicts with parents; (2) self-ratings of lazy, bored, rejected, and unhealthy, (3) serious suicidal thoughts, delinquent behavior, early use of marijuana and alcohol, and the tendency to drink more than six alcoholic drinks at a sitting; and (4) agreement with the following statements: "If something feels good, I usually do it and don't worry about the consequences" and "I try to play as much as possible and work as little as possible." These findings suggest that many polydrug users and abusers are either seeking pleasure or trying to escape pain. Because of the different reasons behind polydrug use, a variety of treatment and prevention strategies will be necessary to curb the polydrug problem among adolescents.

Adolescent↗
PubMed1984

Prenatal weight gain and postpartum weight loss patterns in adolescents.

The standard weight gain curve for pregnant females is used for all ages but its suitability for pregnant adolescents has not been satisfactorily examined. The purpose of this project was to compare prenatal weight gain patterns of 80 adolescents (13-17 yr old) with those of the standard curve. Girls who were chronologically and physiologically younger tended to gain less weight prenatally then older girls. Girls who were underweight prior to pregnancy gained more weight prenatally than other girls. Term weight gain averaged 37 lb. Increase in height was not recorded during the course of the investigation. The development of standard curves for adolescents must be based on a larger study population, but the curves presented here are an important initial step toward achieving this goal.

Adolescent↗
PubMed1982

Parental permission to date and its relationship to drug use and suicidal thoughts among adolescents.

The primary purpose of this research was to determine the effects of early and late parental permission to begin dating. To accomplish this, relationships were determined between the age youngsters reported that their parents let them begin dating and the variables which relate to the participants': (1) self concept; (2) perception of their parents; (3) reported drinking and drug abuse problems; (4) reported delinquent behavior; (5) serious suicidal thoughts; (6) frequency of drug use; and (7) frequency of dating before gaining parental permission. Early permission to date was found to be significantly related to feelings of being confident, independent and tired, good relationship with mother, reported drinking and drug abuse problems, and frequent use of alcohol, marijuana, downers, cocaine and tobacco. Late permission was significantly related to feelings of being unsure, dependent and refreshed, poor relationship with mother, maternal over-strictness, and serious suicidal thoughts. In comparison to those who received parental permission to date when they were 15, both earlier and later daters were more likely to report dating before obtaining parental permission, and more likely to report either daily drug use or serious suicidal thoughts. It appears that the year following the 15th birthday may be the most appropriate time for parents to allow (or encourage) their children to begin dating.

Adolescent↗
PubMed1980

Enzymatic methylation of calmodulin in rat brain cytosol.

The methylation of brain peptides was investigated by incubating brain high speed supernatant fractions with S-adenosyl-L-[methyl-3H]methionine and resolving the radioactive peptide products by polyacrylamide gradient gel electrophoresis. Peptides of 17,000, 21,000, 29,000, and 34,000 daltons were methylated in vitro; the 17,000-dalton peptide had the same electrophoretic mobility as authentic calmodulin and showed the shift in electrophoretic mobility in the presence of EGTA which is characteristic of calmodulin. The identification of the 17,000-dalton peptide as calmodulin was confirmed by electrophoresis under nondenaturing conditions and by two-dimensional isoelectric focusing electrophoresis. The enzyme responsible for calmodulin methylation and its substrate, the putative desmethylcalmodulin, were separated from one another by chromatography on DEAE-cellulose. When this partially purified enzyme was incubated with the substrate-containing fraction, calmodulin was the only methylated product. A test tube assay for calmodulin N-methyltransferase was developed and validated by comparison with calmodulin methylation assessed by gel electrophoresis. Both procedures showed that calmodulin methyltransferase is inhibited by EGTA and stimulated by divalent cations, with manganese giving the highest activity. Similar values for ph optimum and kinetic constants were obtained when the electrophoresis and test tube assays were compared. A rapid chromatographic procedure for the separation of methylated lysines and arginines was developed and used to demonstrate that epsilon-trimethyllysine is the radioactive amino acid formed when calmodulin is methylated in vitro. The methyltransferse, which is distinguished from previously described methylase III enzymes by its divalent cation requirement and substrate specificity, is thus designated as S-adenosyl-L-methionine calmodulin lysine methyltransfease.

Animals↗
PubMedDate not supplied

Regional protein alterations in rat kidneys induced by lead exposure.

Lead is a potent neuro- and nephrotoxin in humans and a renal carcinogen in rats. Previous studies have detected lead-induced increases in the activities of specific detoxification enzymes in distinct kidney cell types preceding irreversible renal damage. While preferential susceptibility of the highly vascularized cortex to the effects of lead is clear, lead effects on the medullary region have remained unexplored. The present study was undertaken to investigate the extent to which regional renal protein expression differs and to determine which, if any, regionally distinct protein markers indicative of lead's renotoxic mechanism might be detected in kidney cortical and medullary cytosols. We examined protein expression in these two functionally and anatomically distinct regions, and identified several proteins that are differentially expressed in those regions and were significantly altered by lead. Kidney cytosols from rats injected with lead acetate (114 mg/kg, three consecutive daily injections) were separated by two-dimensional electrophoresis. Lead exposure significantly (P<0.001) altered the abundance (either or) of 76 proteins in the cortex and only 13 in the medulla. Eleven of the proteins altered in the protein patterns were conclusively identified either by matrix-assisted laser desorption/ionization mass spectrometry/electrospray ionization-mass spectrometry (MALDI-MS/ESI-MS) analysis of peptide digests, immunological methods, or by gel matching. Several of the cortical proteins altered by lead were unchanged in the medulla while others underwent similar but lesser alterations. These observations reflect the complexity of lead's nephrotoxicity and endorse the application of proteomics in mechanistic studies as well as biomarker development in a variety of toxicologic paradigms.

Amino Acid Sequence↗