Biomedical subjects

Wendy Johnson

Publications and source records attributed to Wendy Johnson.

17 recordsLinked to original sources

PubMed2006

Genetic and environmental influences on academic achievement trajectories during adolescence.

Most studies have considered the effects of particular characteristics on academic achievement individually, which means that little is known about how they function together. Using the population-based Minnesota Twin Family Study, the authors investigated the effects of child academic engagement (interest, involvement, effort), IQ, depression, externalizing behavior, and family environmental risk on academic achievement (reported school grades) from ages 11 through 17. Hierarchical linear growth curve modeling showed main effects on initial reported Grades for all variables, and IQ mitigated the deleterious effects of family risk and externalizing. Only engagement affected change in Grades through adolescence. Influences on initial Grades were strongly genetically influenced, associated primarily with IQ, engagement, and externalizing behavior. Shared environmental influences on initial Grades linked engagement, IQ, and family risk. Genetic influences on change in Grades were substantial, but they were not associated with the academic, family risk, and mental health covarying factors. These results indicate that age 11 achievement and change in achievement through adolescence show systematic patterns and document the existence of individual differences in the commonly shared developmental experience of adapting to the school environment.

Achievement↗

PubMed2006

How money buys happiness: genetic and environmental processes linking finances and life satisfaction.

Measures of wealth such as income and assets are commonly considered to be objective measures of environmental circumstances, making direct contributions to life satisfaction. Here, the authors explored the accuracy of this assumption. Using a nationwide sample of 719 twin pairs from the National Survey of Midlife Development in the United States, the authors first noted the relative independence of most perceptions about financial status from measures of actual wealth. They then demonstrated that perceived financial situation and control over life completely mediated the association between measures of actual wealth and life satisfaction. Finally, they showed that financial resources appeared to protect life satisfaction from environmental shocks. In addition, control appeared to act as a mechanism translating life circumstances into life satisfaction.

Adult↗

PubMed2006

Hyaluronic acid binding peptides prevent experimental staphylococcal wound infection.

Staphylococcus aureus is a major cause of surgical wound infections. The development of mechanisms of antimicrobial resistance by this and other bacterial pathogens has prompted the search for new approaches to treat infectious diseases. Hyaluronic acid binding peptides have been shown to modulate cellular trafficking during host responses and were assessed for their ability to treat and possibly prevent experimental surgical wound infections caused by S. aureus. Treatment with these peptides was highly efficacious in reducing the number of S. aureus cells at the wound site and ameliorated the inflammatory host response associated with these infections. These data suggest a novel approach for the treatment and prophylaxis of staphylococcal wound infections in the clinical setting.

Amino Acid Sequence↗

PubMed2005

Genetic effects on physical health: lower at higher income levels.

Given the robust finding that people in higher income groups tend to experience better physical health, there is interest in identifying mechanisms underlying this gradient. Using a nationwide sample of 719 twin pairs from the National Survey of Midlife Development in the United States, we investigated the possibility that gene-environment interaction underlies the income-health gradient. We observed that genetic variance associated with 2 measures of physical health, number of chronic illnesses and body mass index, each declined significantly with increasing income. This interaction effect could not be removed by adjusting income for the presence of health insurance coverage and education, suggesting that the interaction is not simply a result of differences in levels of those characteristics with income.

Adult↗

PubMed2005

Higher perceived life control decreases genetic variance in physical health: evidence from a national twin study.

Physical health has been linked consistently with both income and sense of control, and the authors previously demonstrated that genetic variation in physical health measures decreased with increasing income (see W. Johnson & R. F. Krueger, 2004). Using a nationwide sample of 719 twin pairs from the MacArthur Foundation National Survey of Midlife Development in the United States, in this study the authors show that genetic variation in physical health measures (number of chronic illnesses and body mass index) also decreases with increasing sense of control. The authors integrate findings for income and control by demonstrating an interaction between genetic influences on sense of control and income in explaining physical health. They hypothesize that the mechanism underlying the interaction is the known biological relationship between metabolic efficiency and adaptation to stressful environments.

Adaptation, Physiological↗

PubMed2005

Predictors of physical health: toward an integrated model of genetic and environmental antecedents.

People in higher-income groups tend to experience better physical health, yet this does not appear to be the direct result of access to medical care. This has prompted a search for psychological factors more likely to be present in high-income environments that might help to explain the relationship. Physical health has been associated with a number of such psychological measures including positive affect and well-being, negative affect and neuroticism, positive social relationships, and perceived control. Building from recent findings of moderation of genetic variance in physical health by income and perceived control, we explore the genetic and environmental relationships among all these variables in a nationwide U.S. twin sample. These relationships suggest possible mechanisms by which psychological characteristics, behaviors, physical health, and environmental circumstances could be influenced by common groups of genes with varying degrees of activity in different environments. We discuss the implications of such mechanisms for differential expression of genetic variation in the population and suggest ways in which consideration of such effects can inform gerontology research.

Causality↗

PubMed2005

Melatonin, sleep, and shift work adaptation.

BACKGROUND: Night work is associated with disrupted circadian rhythms, fatigue, accidents, and chronic disease. Melatonin secretion helps regulate sleep and circadian rhythms. OBJECTIVE: Melatonin, sleep disturbances, and symptoms (sleep, fatigue, mental) were compared among workers on permanent day, swing, and night shifts. METHODS: Urinary 6-hydroxymelatonin sulfate (6-OHMS) was measured in postwork and postsleep samples. Disrupted circadian melatonin production was evaluated using the sleep:work 6-OHMS ratio. Wrist actigraphy characterized light exposures and sleep characteristics. RESULTS: Night workers had altered melatonin, disrupted sleep, and elevated symptom prevalence. Subjects grouped by their sleep:work 6-OHMS ratio rather than shift had even greater symptom prevalence. Risks for two or more symptoms were 3.5 to 8 times greater among workers with sleep:work ratios < or =1 compared to those with ratios >1. CONCLUSIONS: This ratio may help identify workers at increased risk for accidents or injuries.

Accidents, Occupational↗

PubMed2005

Personality stability in late adulthood: a behavioral genetic analysis.

A sample of 833 twins from the Minnesota Twin Study of Adult Development and Aging completed the Multidimensional Personality Questionnaire (MPQ; Tellegen, 1982) twice, averaging 59.4 (sd=9.7) years of age at first and 64.4 (sd=10.2) years of age at second testing (average retest interval 5.0 years, sd=2.36, range 1.0-10.4 years). Both means and standard deviations of scale scores were extremely stable from first to second testing. In addition, sample participants tended to retain their rank order on the scales (average r=.76 across scales). Bivariate biometric analyses showed that the genetic influences on most of the scale scores were almost perfectly correlated across the two waves (range .95 to 1.00). The nonshared environmental influences were also highly correlated across the two waves (range .53 to .73). Models specifying identical variance components at the two time points and fixing the genetic correlation to 1.00 provided improved fit. The results suggest that the high stability of personality in later adulthood has a strong genetic foundation, supplemented by stability of environmental effects.

Aged↗

PubMed2005

Diversity of genome structure in Salmonella enterica serovar Typhi populations.

The genomes of most strains of Salmonella and Escherichia coli are highly conserved. In contrast, all 136 wild-type strains of Salmonella enterica serovar Typhi analyzed by partial digestion with I-CeuI (an endonuclease which cuts within the rrn operons) and pulsed-field gel electrophoresis and by PCR have rearrangements due to homologous recombination between the rrn operons leading to inversions and translocations. Recombination between rrn operons in culture is known to be equally frequent in S. enterica serovar Typhi and S. enterica serovar Typhimurium; thus, the recombinants in S. enterica serovar Typhi, but not those in S. enterica serovar Typhimurium, are able to survive in nature. However, even in S. enterica serovar Typhi the need for genome balance and the need for gene dosage impose limits on rearrangements. Of 100 strains of genome types 1 to 6, 72 were only 25.5 kb off genome balance (the relative lengths of the replichores during bidirectional replication from oriC to the termination of replication [Ter]), while 28 strains were less balanced (41 kb off balance), indicating that the survival of the best-balanced strains was greater. In addition, the need for appropriate gene dosage apparently selected against rearrangements which moved genes from their accustomed distance from oriC. Although rearrangements involving the seven rrn operons are very common in S. enterica serovar Typhi, other duplicated regions, such as the 25 IS200 elements, are very rarely involved in rearrangements. Large deletions and insertions in the genome are uncommon, except for deletions of Salmonella pathogenicity island 7 (usually 134 kb) from fragment I-CeuI-G and 40-kb insertions, possibly a prophage, in fragment I-CeuI-E. The phage types were determined, and the origins of the phage types appeared to be independent of the origins of the genome types.

Chromosomes, Bacterial↗

PubMed2004

Marriage and personality: a genetic analysis.

There is substantial evidence that married people fare better than their unmarried peers on many life outcome variables. The authors asked whether self-selection might partially explain these benefits through genetic influences on personality contributing to propensity to marry. Using a population-based sample of 4,225 women and 2,869 men that included 2,527 complete twin pairs, the authors investigated the phenotypic associations between personality and propensity to marry, the heritability of propensity to marry, and the extent of genetic influence on the link between personality and propensity to marry. The results suggest that propensity to marry is heritable and that the phenotypic link between personality and propensity to marry is genetically influenced.

Adult↗

PubMed2003

Endothelin-1 and vascular tone in subjects with atherogenic risk factors.

Endothelin-1 (ET-1) is a potent vasoconstrictor that increases vascular tone in the resistance vessels of subjects with hypertension. It is unclear whether endogenous ET-1 affects resistance-vessel function equally in patients with other cardiovascular risk factors. Vasoconstriction to ET-1 is mediated principally via the endothelin-A (ETA) receptor on vascular smooth muscle cells. Accordingly, we used an ETA-specific antagonist, BQ-123, to test the hypothesis that endogenous ET-1 increases vascular resistance selectively in subjects with hypertension compared with other risk factors. BQ-123 was infused at 100 nmol/min for 80 minutes into the brachial artery of 10 subjects with hypertension (mean+/-SEM arterial pressure, 106+/-5 mm Hg), 12 subjects with hypercholesterolemia (mean+/-SEM total cholesterol, 7.1+/-0.2 mmol/L), 10 active smokers (mean+/-SEM, 42+/-11 pack-years), and 11 healthy, age-matched individuals. Forearm blood flow (FBF) was measured by venous occlusion plethysmography. BQ-123 dilated resistance arterioles in hypertensive subjects, with FBF's increasing by 46+/-7% from baseline (P<0.001). BQ-123 increased FBF to a lesser extent in hypercholesterolemic (24+/-5%, P<0.001) and healthy (20+/-8%, P=0.007) individuals but did not affect FBF significantly in smokers (10+/-8%, P=0.185). The vasodilator response in hypertensive subjects, but not in hypercholesterolemic patients or smokers, was significantly greater than that in healthy individuals (P=0.012). Endogenous ET-1, acting via the ETA receptor, increases resistance-vessel tone in subjects with hypertension more than in subjects with hypercholesterolemia or in smokers. These results indicate that ET-1 contributes more to the pathophysiology of hypertension than of other risk factors in subjects without overt atherosclerosis.

Arteriosclerosis↗

PubMed2002

Exhaled nitric oxide: a marker of pulmonary hemodynamics in heart failure.

OBJECTIVES: We sought to test the hypothesis that patients with decompensated heart failure (HF) lose a compensatory process whereby nitric oxide (NO) maintains pulmonary vascular tone. BACKGROUND: Exhaled nitric oxide (eNO) partially reflects vascular endothelial NO release. Levels of eNO are elevated in patients with compensated HF and correlate inversely with pulmonary artery pressures (PAP), reflecting pulmonary vasodilatory activity. METHODS: We measured the mean mixed expired NO content of a vital-capacity breath using chemiluminescence in patients with compensated HF (n = 30), decompensated HF (n = 7) and in normal control subjects (n = 90). Pulmonary artery pressures were also measured in patients with HF. The eNO and PAP were determined sequentially during therapy with intravenous vasodilators in patients with decompensated HF (n = 7) and in an additional group of patients with HF (n = 13) before and during administration of milrinone. RESULTS: The eNO was higher in patients with HF than in control subjects (9.9 +/- 1.1 ppb vs. 6.2 +/- 0.4 ppb, p = 0.002) and inversely correlated with PAP (r = -0.81, p < 0.00001). In marked contrast, patients with decompensated HF exhibited even higher levels of eNO (20.4 +/- 6.2 ppb) and PAP, but there was a loss of the inverse relationship between these two variables. During therapy (7.3 +/- 6 days) with sodium nitroprusside and diuresis, hemodynamics improved, eNO concentrations fell (11.2 +/- 1.2 ppb vs. before treatment, p < 0.05), and the relationship between eNO and PAP was restored. After milrinone, eNO rose proportionally with decreased PAP (p < 0.05). CONCLUSIONS: Elevated eNO may reflect a compensatory circulatory mechanism in HF that is lost in patients with clinically decompensated HF. The eNO may be an easily obtainable and quantifiable measure of the response to therapy in advanced HF.

Adult↗

PubMed2002

Neurohormonal activation rapidly decreases after intravenous therapy with diuretics and vasodilators for class IV heart failure.

OBJECTIVES: This study was designed to determine whether therapy with vasodilators and diuretics, designed to normalize loading conditions in decompensated heart failure (HF), reduces neurohormonal activation in the short term. BACKGROUND; Elevated vasoactive neurohormone levels in chronic HF have adverse prognostic impact and may be targeted by specific therapies. METHODS: Endothelin-1, catecholamines, renin, aldosterone, angiotensin and atrial natriuretic peptides (ANP, N-ANP and BNP) were measured in 34 patients with advanced HF before and after hemodynamically guided therapy with vasodilators and diuretics. The therapy was designed to reduce filling pressures and systemic vascular resistance (SVR) without inotropic therapy. Blood was drawn before therapy (A), after initial diuretic and nitroprusside therapy to optimize hemodynamics (B, mean 1.4 days) and after transition to an oral regimen designed to maintain improved hemodynamics (C, mean 3.4 days). RESULTS: Mean pulmonary wedge pressure fell from 31 to 18 mm Hg, right atrial pressure from 15 to 8 mm Hg, and SVR from 1,780 to 1,109 dynes/s/cm(-5). Cardiac index increased from 1.7 to 2.6 l/min/m(2) without intravenous inotropic agents (all p < or = 0.05). Average endothelin levels declined by 30%, from 7.7 to 5.5 pg/ml, and remained low at time point C, 5.2 pg/ml (p < 0.01). Norepinephrine was 858 at time A, 817 at time B, and fell by time C to 608 pg/ml (p < or = 0.05). The mean plasma BNP level fell by 26% after only 1.4 days and by 53% at time C (p < 0.001). CONCLUSIONS: Neurohormonal activation rapidly decreases after short-term therapy tailored to decrease severely elevated filling pressures and SVR without inotropic agents. Therapy designed to address neurohormonal activation should include therapy to improve severe resting hemodynamic compromise.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed2002

Contribution of endothelin to pulmonary vascular tone under normoxic and hypoxic conditions.

The contribution of endothelin to resting pulmonary vascular tone and hypoxic pulmonary vasoconstriction in humans is unknown. We studied the hemodynamic effects of BQ-123, an endothelin type A receptor antagonist, on healthy volunteers exposed to normoxia and hypoxia. Hemodynamics were measured at room air and after 15 min of exposure to hypoxia (arterial PO(2) 99.8 +/- 1.8 and 49.4 +/- 0.4 mmHg, respectively). Measurements were then repeated in the presence of BQ-123. BQ-123 decreased pulmonary vascular resistance (PVR) 26% and systemic vascular resistance (SVR) 21%, whereas it increased cardiac output (CO) 22% (all P < 0.05). Hypoxia raised CO 28% and PVR 95%, whereas it reduced SVR 23% (all P < 0.01). During BQ-123 infusion, hypoxia increased CO 29% and PVR 97% and decreased SVR 22% (all P < 0.01). The pulmonary vasoconstrictive response to hypoxia was similar in the absence and presence of BQ-123 [P = not significant (NS)]. In vehicle-treated control subjects, hypoxic pulmonary vasoconstriction did not change with repeated exposure to hypoxia (P = NS). Endothelin contributes to basal pulmonary and systemic vascular tone during normoxia, but does not mediate the additional pulmonary vasoconstriction induced by acute hypoxia.

Acute Disease↗

PubMed2002

The personalities of twins: just ordinary folks.

Twin studies have demonstrated that personality traits show moderate genetic influence. The conclusions drawn from twin studies rely on the assumptions that twins are representative of the population at large and that monozygotic and dizygotic twins are comparable in every way that might have bearing on the traits being studied. To evaluate these assumptions, we used Multidimensional Personality Questionnaire (MPQ) data from three samples drawn from the Minnesota Twin Registry (totaling 12,971 respondents) to examine the effect sizes associated with mean differences on the 11 MPQ scales and 3 higher-order MPQ factors for singletons versus twins and MZ twins versus DZ twins. The singletons in the samples were family members of the participating twins. We also used ratios of scale variances to examine the significance of variance differences. The only mean or variance difference replicated across all three samples was greater Social Closeness (about.1 standard deviation) for twins than for singletons. This difference was obtained for both males and females. It would appear that, with respect to personality, twins are not systematically different from other people. Our results also highlight the importance of replication in psychological research because each of our large samples showed differences not replicated in other samples.

Analysis of Variance↗

PubMed2002

The Minnesota Twin Registry: current status and future directions.

The Minnesota Twin Registry is a birth-record-based twin registry. Begun in 1983, it includes data for 4307 surviving intact pairs born in Minnesota between 1936 and 1955. In addition, the Registry includes 901 twin pairs born in Minnesota from 1904 to 1934, as well as 391 male pairs born in Minnesota from 1961 to 1964. The research focus is primarily on human individual differences assessed by self-report. Questionnaires completed by the participants include measures of personality, occupational interests, demographics, and leisure-time activities. We outline major contributions that have resulted from Registry research, as well as current and future research directions.

Birth Certificates↗

PubMedDate not supplied

Hospital in the home (HITH) care following autologous stem cell transplantation for lymphoma and multiple myeloma.

BACKGROUND: Advances in outpatient and supportive care and increased pressure on hospital bed usage has led to the investigation of hospital in the home (HITH) management following autologous haematologous stem cell transplantation (AutoHSCT) for patients with multiple myeloma or lymphoma. DESIGN: The Newcastle Mater Hospital Haematology Unit together with the Mater Acute Care Community Service (MACCS) developed a protocol for HITH care following AutoHSCT. OUTCOMES: Clinical outcomes of the protocol were audited: 40% (13) of patients were suitable candidates for HITH care post transplantation. Of these 84.6% (11) were readmitted to the haematology unit within seven days of discharge from hospital. CONCLUSION: Our preliminary experience suggests that with adequate infrastructure support and rigorous patient selection this model of care is both safe and feasible.

Adult↗