Main Effect Of Stress Research Articles

The Relationship Between Occupational ‎Factors and Stress and its ‎Effect on Occupational ‎ Performance during Covid-19 Pandemic: A Case Study of Saveh ‎University of Medical Sciences

Introduction: Occupational stress can cause psychological pressure and subsequently affects the work performance of healthcare workers, especially when unexpected events like contagious disease pandemics occur. Because of the stressful nature of unpredictable life events, it increases the hospital admission rate, which results in heavy workload for employers and this add up to their stress. The present study was conducted with the aim of investigating the relationship between occupational factors and also work stress on occupational performance during covid-19 pandemic using the employees of the Saveh Medical Sciences Health Department in covid-19 epidemic.
 Methods: The present research is a cross-sectional study that 316 employees from the health department of Saveh Faculty of Medical Sciences were given their opinion in 1401. In order to investigate occupational stress management and employee performance, the standard occupational stress assessment questionnaires and Patterson's performance assessment questionnaires were used, respectively. Data analysis was done using SPSS26 software and through frequency report, mean and standard deviation, linear regression test and Stepwise multiple regression model done.
 Results: the average and standard deviation of the total occupational stress management score of the participants was 3.09 ± 0.46, which was in the average range. The variables of the frequency of workplace change and the amount of stress determine 10% of the changes in job performance. ‏‏(‏PES=0/1‏) Examination of the interaction effect of the frequency of workplace change and the amount of stress on job performance did not show a significant relationship. (P-value ‎=0.4) The main effect of the frequency of workplace change (P-value=0.007 ‎ ‏) and the main effect of stress (P-value ‎=0.001) on job performance showed a significant relationship.
 Conclusion: The results of this study showed that there was a significant relationship between types of employment and job performance. To be precise, the lowest mean and standard deviation in job performance observed in the contractual employees who had high levels of stress. While, the highest mean and standard deviation regarding job performance were related to the Permanent employeeswho had low levels of stress (P-value ‎ <0.001). Since increasing job security among contractual employees and corporate contracts and also changing their status can improve their performance, in order to manage job stress, introducing more policies regarding employment is suggested.

Characteristics Analysis of Leakage Current in an Array of InSb Photodetector: The Effect of Compressive and Tensile Stresses

Herein, the effect of tensile and compressive stress on the performance of a 3 × 3 InSb array as an infrared photodetector is investigated. At first, the effect of mesh sizes on simulated results is evaluated and the results are validated with a good agreement. It is shown that the main effect of stress is related to the Γ (bandgap) point of the band structure. This shift causes the densities of intrinsic and minority carriers to decrease in the case of tensile stress and increase in the case of compressive stress. Using a 3D simulation, it is investigated that tensile stress reduces the dark current while compressive stress induces that. However, it is an interesting result that an increment in applied compressive stress interrupts the InSb photodetector performances and vice versa tensile stress helps the photocurrent to have a lower dark current. So, these results can be used to manage the dark current in the field of the photodetector. Finally, the crosstalk of the simulated structure as one of its main characteristics is calculated.

Stressed out and fed up: The effect of stress on maternal feeding behaviors and the moderating role of executive function

Stress is associated with a range of unhealthy eating habits, yet few studies have examined how stress may influence the intergenerational transmission of eating habits from parents to their children. Specifically, there is a lack of data regarding the role of stress on feeding practices. Moreover, most work investigating the associations between parental stress and their feeding behaviors has been correlational, limiting our understanding of causality. In the current study, we used an experimental design, induced high and low stress in mothers using a standard laboratory stressor, and observed mother-child interactions during a snack break. We also examined the potential role of maternal executive functioning (EF) for buffering the effects of stress on maternal feeding behaviors. Levels of maternal stress were manipulated with the Trier Social Stress Task (TSST) in a community sample (N = 80 dyads, Child Mage = 41.89 months, female = 43). We measured maternal EF with a series of computerized tasks. Maternal feeding behaviors were coded for controlling behaviors, which included pressuring and restricting behaviors. Results indicate a main effect of stress on controlling feeding behaviors, such that mothers in the high-stress condition exhibited higher levels of controlling behaviors. The effect of stress on controlling feeding behaviors was ameliorated among mothers with higher levels of EF after controlling for child age and income. Results provide causal evidence for the role of stress on feeding behaviors and suggest EF as a factor to be considered in the treatment and prevention of diet-related illnesses.

Functions of the ventromedial prefrontal cortex in emotion regulation under stress

Recent neuroimaging studies suggest that the ventromedial prefrontal cortex (vmPFC) contributes to regulation of emotion. However, the adaptive response of the vmPFC under acute stress is not understood. We used fMRI to analyse brain activity of people viewing and rating the emotional strength of emotional images after acute social stress. Here, we show that the vmPFC is strongly activated by highly emotional images, indicating its involvement in emotional regulation, and that the midbrain is activated as a main effect of stress during the emotional response. vmPFC activation also exhibits individual differences in behavioural scores reflecting individual reactions to stress. Moreover, functional connectivity between the vmPFC and midbrain under stress reflects stress-induced emotion regulation. Those results suggest that the functions of the network including the vmPFC in emotion regulation is affected by stress depending on the individuals' level of reaction to the stress.

Electrophysiological Differentiation of the Effects of Stress and Accent on Lexical Integration in Highly Fluent Bilinguals

Individuals who acquire a second language (L2) after infancy often retain features of their native language (L1) accent. Cross-language priming studies have shown negative effects of L1 accent on L2 comprehension, but the role of specific speech features, such as lexical stress, is mostly unknown. Here, we investigate whether lexical stress and accent differently modulate semantic processing and cross-language lexical activation in Welsh–English bilinguals, given that English and Welsh differ substantially in terms of stress realisation. In an L2 cross-modal priming paradigm, we manipulated the stress pattern and accent of spoken primes, whilst participants made semantic relatedness judgments on visual word targets. Event-related brain potentials revealed a main effect of stress on target integration, such that stimuli with stress patterns compatible with either the L1 or L2 required less processing effort than stimuli with stress incompatible with both Welsh and English. An independent cross-language phonological overlap manipulation revealed an interaction between accent and L1 access. Interestingly, although it increased processing effort, incorrect stress did not significantly modulate semantic priming effects or covert access to L1 phonological representations. Our results are consistent with the concept of language-specific stress templates, and suggest that accent and lexical stress affect speech comprehension mechanisms differentially.

Effects of stress on functional connectivity during problem solving

AimOur purpose was to examine how stress affects functional connectivity (FC) in language processing regions of the brain during a verbal problem solving task associated with creativity. We additionally explored how gender and the presence of the stress-susceptible short allele of the serotonin transporter gene polymorphism influenced this effect. MethodsForty-five healthy participants (Mean age: 19.6 ​± ​1.6 years; 28 females) were recruited to be a part of this study and genotyped to determine the presence or absence of at least one copy of the short (S) allele of the serotonin transporter gene, which is associated with greater susceptibility to stress. The participants underwent functional magnetic resonance imaging in two separate sessions (stress and no stress control). One session utilized a modified version of the Montreal Imaging Stress Test (MIST) to induce stress while the other session consisted of a no stress control task. The MIST and control tasks were interleaved with task blocks during which the participants performed the compound remote associates task, a convergent task that engages divergent thinking, which is a critical component of creativity. We examined the relationship between stress effects on performance and effects on connectivity of language processing regions activated during this task. ResultsThere was no main effect of stress on functional connectivity for individual ROI pairs. However, in the examination of whether stress effects on performance related to effects on connectivity, changes in middle temporal gyrus connectivity with stress correlated positively with changes in solution latency for individuals with the S allele, but anti-correlated for those with only the L allele. A trend towards a gene ​× ​stress interaction on solution latency was also observed. DiscussionResults from the study suggest that genetic susceptibility to stress, such as the presence of the S allele, affects neural correlates of performance on tasks related to verbal problem solving, as indicated by connectivity of the middle temporal gyrus. Future work will need to determine whether connectivity of the middle temporal gyrus serves as a marker for the effect of stress susceptibility on cognition, extending into stress susceptible patient populations.

Cerebrovascular regulation is not blunted during mental stress.

What is the central question of the study? What are the effects of acute mental stress on the mechanisms regulating cerebral blood flow? What is the main finding and its importance? The major new findings are as follows: (i) high mental stress and hypercapnia had an interactive effect on mean middle cerebral artery blood velocity; (ii) high mental stress altered the regulation of cerebral blood flow; (iii) the increased cerebrovascular hypercapnic reactivity was not driven by changes in mean arterial pressure alone; and (iv) this increased perfusion with mental stress appeared not to be justified functionally by an increase in oxygen demand (as determined by near-infrared spectroscopy-derived measures). In this study, we examined the effects of acute mental stress on cerebrovascular function. Sixteen participants (aged 23±4years; five female) were exposed to low and high mental stress using simple arithmetic (counting backwards from 1000) and more complex arithmetic (serial subtraction of 13 from a rapidly changing four-digit number), respectively. During consecutive conditions of baseline, low stress and high stress, end-tidal partial pressure of CO2 ( ) was recorded at normocapnia (37±3mmHg) and clamped at two elevated levels (P<0.01): 41±1 and 46±1mmHg. Mean right middle cerebral artery blood velocity (MCAvmean ; transcranial Doppler ultrasound), right prefrontal cortex haemodynamics (near-infrared spectroscopy) and mean arterial blood pressure (MAP; finger photoplethysmography) were measured continuously. Cerebrovascular hypercapnic reactivity (ΔMCAvmean /Δ ), cerebrovascular conductance (CVC; MCAvmean /MAP), CVC CO2 reactivity (ΔCVC/Δ ) and total peripheral resistance (MAP/cardiac output) were calculated. Acute high mental stress increased MCAvmean by 7±7%, and more so at higher (32±10%; interaction, P=0.03), illustrating increased sensitivity to CO2 (i.e. its major regulator). High mental stress also increased MAP (17±9%; P ≤ 0.01), coinciding with increased near-infrared spectroscopy-derived prefrontal haemoglobin volume and saturation measures. High mental stress elevated both cerebrovascular hypercapnic and conductance reactivities (main effect of stress, P ≤ 0.04). These findings indicate that the cerebrovascular response to acute high mental stress results in a coordinated regulation between multiple processes.

Association Between Interleukin-6 and Striatal Prediction-Error Signals Following Acute Stress in Healthy Female Participants

BackgroundStress is widely known to alter behavioral responses to rewards and punishments. It is believed that stress may precipitate these changes through modulation of corticostriatal circuitry involved in reinforcement learning and motivation, although the intervening mechanisms remain unclear. One candidate is inflammation, which can rapidly increase following stress and can disrupt dopamine-dependent reward pathways. MethodsHere, in a sample of 88 healthy female participants, we first assessed the effect of an acute laboratory stress paradigm on levels of plasma interleukin-6 (IL-6), a cytokine known to be both responsive to stress and elevated in depression. In a second laboratory session, we examined the effects of a second laboratory stress paradigm on reward prediction error (RPE) signaling in the ventral striatum. ResultsWe show that individual differences in stress-induced increases in IL-6 (session 1) were associated with decreased ventral striatal RPE signaling during reinforcement learning (session 2), though there was no main effect of stress on RPE. Furthermore, changes in IL-6 following stress predicted intraindividual variability in perceived stress during a 4-month follow-up period. ConclusionsTaken together, these data identify a novel link between IL-6 and striatal RPEs during reinforcement learning in the context of acute psychological stress, as well as future appraisal of stressful life events.

FKBP5 genotype and early life stress exposure predict neurobehavioral outcomes for preterm infants.

This study evaluated the relationship between stressful early life neonatal intensive care unit (NICU) experiences, genetic variation of a stress response-associated gene (FKBP5), and neurobehavioral outcomes. The impact of genetic variation and stress experience on neurobehavioral outcomes was examined for 41 preterm infants. Statistical analyses explored the main effects of FKBP5 genotype and NICU stress experience, as well as their interaction on infant neurobehavioral development prior to discharge. Statistical analyses demonstrated a relationship between both FKPB5 genotype and stress related to NICU care that were independently associated with neurobehavioral outcomes; indicating a main effect of genotype and a main effect of stress on neurodevelopment. Additionally, we found an interaction between the minor allele genotype and NICU stress potentially associated with less favorable developmental progress at discharge. Evidence of genetic and environmental risk factors for neurodevelopmental impairment suggests the need for improved evidence-based practice initiatives to protect those most vulnerable to the combination of genetic susceptibility to stress and medical fragility.

Effects of stress early in gestation on hippocampal neurogenesis and glucocorticoid receptor density in pregnant rats

Pregnancy is a time of marked neural, physiological and behavioral plasticity in the female and is often a time when women are more vulnerable to stress and stress-related diseases, such as depression and anxiety. Unfortunately the impact of stress during gestation on neurobiological processes of the mother has yet to be fully determined, particularly with regard to changes in the hippocampus; a brain area that plays an important role in stress-related diseases. The present study aimed to determine how stress early in pregnancy may affect hippocampal plasticity in the pregnant female and whether these effects differ from those in virgin females. For this purpose, adult age-matched pregnant and virgin female Sprague–Dawley rats were divided into two conditions: (1) Control and (2) Stress. Females in the stress condition were restrained during days 5–11 of gestation and at matched time-points in virgin females. All pregnant females received an injection of bromodeoxyuridine (BrdU) on day 1 of gestation and were sacrificed 21days later. The same procedure was carried out at matched time points in virgin females. Results show that for number of Ki67-immunoreactive (ir) cells and doublecortin (DCX)-ir cells, there were significant interactions between reproductive state (pregnant/virgin) and stress exposure (p=.05, p=.04, respectively) with control virgin and stressed pregnant females having more Ki67-ir cells than control pregnant females and more DCX-ir cells than stressed virgin females. Results also show that pregnant females had significantly greater glucocorticoid receptor (GR) density in the CA1, CA3 and granule cell layer compared to virgin females. In addition, there was a main effect of stress on GR density in the CA3 region, with stressed females having significantly lower GR density compared to control females (p=.01). This work adds to our understanding of how stress and reproductive state affect plasticity in the female hippocampus.

Stress, race, and APOE: understanding the interplay of risk factors for changes in cognitive functioning

Objectives: Biological and environmental factors are thought to contribute to the development of cognitive decline (CD). The Apolipoprotein E (APOE) ϵ4 allele is the greatest known genetic risk factor. The current study focused on the extent to which environmental factors, specifically stress, influence the relationship between the APOE allele and cognitive functioning and whether this relationship is stronger for African-Americans compared to Caucasians.Methods: Participants consisted of community-dwelling older adults from the Duke Established Populations for Epidemiologic Studies of the Elderly (N = 4,162). Data were drawn from two waves, which were three years apart. Cognitive functioning was assessed at both waves using the Short Portable Mental Status (SPMSQ).Results: Whereas there was no main effect of stress, there was a significant interaction between APOE status and stressful life events, such that increased stress in individuals with an ϵ4 allele lead to more errors on the SPMSQ than individuals with no allele. Inconsistent with predictions, there was a significant interaction between stress and race such that increased stressful events predicted CD in Caucasians but not African-Americans.Conclusions: Recent stressful late-life events have a greater impact on the cognitive status of individuals with an ϵ4 allele. While Caucasians appear to be less vulnerable to cognitive losses at lower levels of stress, as the number of stressful life events increases that advantage disappears for Caucasians.

Stress‐induced increase in muscle force: truth or myth?

Stress‐induced increase in muscle force: truth or myth?

ANTIBIOTIC RESISTANCE AND STRESS IN THE LIGHT OF FISHER'S MODEL

The role of mutations in evolution depends upon the distribution of their effects on fitness. This distribution is likely to depend on the environment. Indeed genotype-by-environment interactions are key for the process of local adaptation and ecological specialization. An important trait in bacterial evolution is antibiotic resistance, which presents a clear case of change in the direction of selection between environments with and without antibiotics. Here, we study the distribution of fitness effects of mutations, conferring antibiotic resistance to Escherichia coli, in benign and stressful environments without drugs. We interpret the distributions in the light of a fitness landscape model that assumes a single fitness peak. We find that mutation effects (s) are well described by a shifted gamma distribution, with a shift parameter that reflects the distance to the fitness peak and varies across environments. Consistent with the theoretical predictions of Fisher's geometrical model, with a Gaussian relationship between phenotype and fitness, we find that the main effect of stress is to increase the variance in s. Our findings are in agreement with the results of a recent meta-analysis, which suggest that a simple fitness landscape model may capture the variation of mutation effects across species and environments.

Psychological stress and reproductive aging among pre-menopausal women

Life history models suggest that biological preparation for current versus longer term reproduction is favored in environments of adversity. In this context, we present a model of reproductive aging in which environmental adversity is proposed to increase the number of growing follicles at the cost of hastening the depletion of the ovarian reserve over time. We evaluated this model by examining psychological stress in relation to reproductive aging indexed by antral follicle count (AFC), a marker of total ovarian reserve. We hypothesized that stress would be related to (i) higher AFC in younger women, reflecting greater reproductive readiness as well as (ii) greater AFC loss across women, reflecting more accelerated reproductive aging. In a multi-ethnic, community sample of 979 participants [ages 25-45 (mean (standard deviation) = 35.2 (5.5)); 27.5% Caucasian] in the Ovarian Aging study, an investigation of the correlates of reproductive aging, the interaction of age-x-stress was assessed in relation to AFC to determine whether AFC and AFC loss varied across women experiencing differing levels of stress. Stress was assessed by the perceived stress scale and AFC was assessed by summing the total number of antral follicles visible by transvaginal ultrasound. In linear regression examining AFC as the dependent variable, covariates (race/ethnicity, socio-economic status, menarcheal age, hormone-containing medication for birth control, parity, cigarette smoking, bodymass index, waist-to-hip ratio) and age were entered on step 1, stress on step 2 and the interaction term (age-x-stress) on step 3. On step 3, significant main effects showed that older age was related to lower AFC (b = -0.882, P = 0.000) and greater stress was related to higher AFC (b = 0.545, P = 0.005). Follow-up analyses showed that the main effect of stress on AFC was present in the younger women only. A significant interaction term (b = -0.036, P = 0.031) showed the relationship between age and AFC varied as function of stress. When the sample was divided into tertiles of stress, the average follicle loss was -0.781, -0.842 and -0.994 follicles/year in the low-, mid- and high-stress groups, respectively. Psychological stress was related to higher AFC among younger women and greater AFC decline across women, suggesting that greater stress may enhance reproductive readiness in the short term at the cost of accelerating reproductive aging in the long term. Findings are preliminary, however, due to the cross-sectional nature of the current study.

Brisk walking reduces ad libitum snacking in regular chocolate eaters during a workplace simulation

Workplace snacking can contribute to obesity. Exercise reduces chocolate cravings but effects on chocolate consumption are unknown. This study investigated the effect of brief exercise on ad libitum consumption during breaks in a computerised task. Seventy-eight regular chocolate eaters, age: 24.90 ± 8.15 years, BMI: 23.56 ± 3.78 kg/m 2 abstained for 2 days. They were randomly assigned to one of four conditions, in a 2 × 2 factorial design, involving either a 15 min brisk walk or quiet rest, and then computerised Stroop tasks with low or high demanding conditions, in three 180 s blocks with a 90 s interval. Throughout, a pre-weighed bowl of chocolates was available for ad libitum eating. A two-way ANOVA revealed no interaction effect of exercise and stress on total chocolate consumption, or main effect of stress, but a main effect of exercise [ F(1, 74) = 7.12, p < .01]. Mean (SD) chocolate consumption was less ( t(73.5) = 2.69, 95% CI for difference 3.4–22.9, ES = 0.61) for the exercise (15.6 g) than control (28.8 g) group. Exercise also increased affective activation, but there was no mediating effect of change in affect on chocolate consumption. A brief walk may help to reduce ad libitum snacking in regular chocolate eaters.

An Acute Psychosocial Stressor Does Not Potentiate Alcohol Cue Reactivity in Non-Treatment-Seeking Alcoholics

Relapse risk factors, such as psychological stress and alcohol cues, are often encountered together. Understanding how they interact has the potential to improve alcoholism treatments. This study was conducted to examine whether an acute psychosocial stressor enhanced alcohol cue reactivity in non-treatment-seeking alcoholics. Seventy-nine alcohol-dependent individuals (39 women) randomly received either the Trier Social Stress Test or a no-stress control condition. Stress reactivity was measured with serum adrenocorticotropic hormone and cortisol, mean arterial blood pressure, and subjective distress. Immediately following the stress manipulation, participants held and sniffed a neutral cue then their preferred alcoholic beverage. Cue reactivity was measured by 2 subjective measures of craving following each cue. Additionally, general craving was assessed with the Alcohol Urge Questionnaire at the beginning and end of the laboratory procedure. The stress manipulation showed internal validity on all measures of stress reactivity. There was not a main effect of stress nor a stress × cue interaction on either cue reactivity measure. As expected, there was a main effect of cue (alcohol > neutral cue) on both measures of cue reactivity. General craving increased during the challenge, but not differently by stress group. Magnitude of stress reactivity was not associated with magnitude of cue reactivity, and all results were independent of gender. In this well-controlled clinical laboratory study of non-treatment-seeking alcoholics, an acute psychological stressor did not make an alcohol cue a more potent urge-inducing stimulus, and stress had no effect on general alcohol craving.

Stress induced changes in cortical and hypothalamic c- fos expression are altered in fragile X mutant mice

Fragile X (FraX) syndrome is characterized by mental retardation and a behavioral phenotype that includes stress-related behaviors. Recently, FraX children were shown to have elevated glucocorticoid hormones under basal conditions and an exaggerated hormonal response to stress. In the present study, fragile X mental retardation 1-knockout (Fmr1-KO) and wild-type (WT) mice were subjected to immobilization stress for 30 min or 2 h, killed with paired controls, and the hippocampus, neocortex, and hypothalamic paraventricular nucleus (PVN) assessed by in situ hybridization for effects on c- fos mRNA. The main effect of stress in hippocampus was a reduction in mRNA levels within CA3–CA1 pyramidal cells in both genotypes. Stress significantly reduced CA1 c- fos mRNA in Fmr1-KOs at 30 min (−41%) and 2 h (−57%), whereas in WTs levels were significantly reduced only at 2 h (−57%). In neocortex, 30 min stress significantly increased c- fos mRNA in Fmr1-KOs only (+53%); however, by 2 h levels were reduced in both genotypes versus respective controls. In the paraventricular nucleus, c- fos mRNA levels were significantly, and equally, increased in both genotypes at 30 min. However, at 2 h, mRNA levels were still elevated in the Fmr1-KOs, whereas they had returned to control values in the WTs. Finally, immobilization stress significantly increased serum corticosterone levels in both genotypes at 30 min and 2 h, with Fmr1-KOs exhibiting greater levels than WTs; levels were statistically different at 2 h. These data indicate a greater response to stress in FraX mutants than in WTs, and further support the hypothesis of a dysregulated hypothalamic–pituitary–adrenal (HPA) axis in FraX syndrome.

Effects of prenatal stress on development in mice: maturation and learning

Female CD-1 mice were stressed during the final week of gestation. Beginning 3 days after birth, until weaning, their pups were examined for eye opening, startle response, tooth eruption, surface righting, ability to cling to and climb an incline, tail pull reflex, rotation, linear movement and exploration. At 3 months of age, they were tested in a Morris Water Maze. Stressed animals were significantly lighter and shorter than non-stressed animals the first week after birth. By 3 days after birth, significantly fewer stressed animals could rotate or right themselves. By 6 days after birth, significantly fewer stressed animals could cling to or climb an inclined screen, or show the tail pull reflex. By 9 days of age, significantly fewer stressed animals had teeth. In contrast, by day 12 of age, significantly more stressed animals demonstrated exploratory behavior than did non-stressed animals. There were no sex differences in the ability of animals to perform these tasks at the same age. Stressed animals were significantly slower than non-stressed animals to reach the hidden platform in the water maze on all trials, and this difference was due to stressed females being slower to find the platform than non-stressed females, with no main effect of stress on males. This study supports and expands previous findings in rodents that prenatal stress can cause deficiencies in some early indices of physical maturation and also that these deficiencies can be continued into adulthood.

Expression of catecholamine-synthesizing enzymes, peptidylglycine alpha-amidating monooxygenase, and neuropeptide Y mRNA in the rat adrenal medulla after acute systemic nicotine.

The expression of catecholamine-synthesizing enzymes in the adrenal medulla is upregulated in parallel by stress and pharmacological treatments. In this study we examined whether a neuropeptide and its processing enzyme are regulated in parallel with catecholamine enzyme genes after drug treatment. Because the main effect of stress on the adrenal medulla is via splanchnic nerve stimulation of nicotinic receptors, we used nicotine to stimulate the medulla and visualized expression of catecholamine enzyme genes, the medullary peptide neuropeptide Y (NPY), and the neuropeptide-processing enzyme peptidylglycine alpha-amidating monooxygenase (PAM) by in situ hybridization quantified by image analysis of autoradiographic images. Rats received a single injection of nicotine (0, 1, or 5 mg/kg sc). Six hours later, rats were transcardially perfused. Free-floating adrenal gland sections were hybridized with 35S-labeled cDNA probes for tyrosine hydroxylase (TH), dopamine beta-hydroxylase (DBH), phenylethanolamine N-methyltransferase (PNMT), PAM, and NPY. Nicotine treatment upregulated the expression of TH, PNMT, and NPY genes in a dose-dependent fashion. Small but nonsignificant increases were observed in DBH and PAM mRNA levels. These results suggest that common transcriptional activation mechanisms may upregulate both catecholamine and neuropeptide synthesis in the adrenal medulla after nicotinic stimulation.

Energy and momentum relaxation of charge carriers in Ge and Si under uniaxial stress

Measurements of the piezoresistance and the energy relaxation time T ϵ , in Ge and Si under uniaxial stress up to 4 kb are reported in the temperature range 30 K < T < 300 K. The measurements of t ϵ have been performed in the warm carrier range using the harmonic mixing technique. The experimental results for the piezoresistance and energy relaxation time in n-type material can roughly be understood in terms of carrier redistribution in the conduction band valleys whose degeneracy is lifted by the stress. Information is obtained from these measurements about the relative strength of ƒ and g type intervalley scattering in n-Si; we find nearly equal coupling strength for both scattering types. For the p-type material the experiments show convincingly that the main effect of stress on transport quantities is also caused by the lifted degeneracy of the heavy and light hole bands, as predicted already by Adams, and by Pikus and Bir. The nonlinear dependence of the piezoresistance and τ ϵ on the stress can very well be explained by approximating the heavy and light hole bands as spherical and parabolical and using the deformation potential constant b as a parameter. The value of ≈2eV obtained for | b| is in good agreement with earlier results for p-Ge.