Direct Depressant Effect Research Articles

Investigating the mediating effect of working memory on intentional forgetting in dysphoria

Our aim was to determine if deficits in intentional forgetting that are associated with depression and dysphoria (subclinical depression) could be explained, at least in part, by variations in working memory function. Sixty dysphoric and 61 non-dysphoric participants completed a modified version of the think/no-think (TNT) task and a measure of complex working memory (the operation span task). The TNT task involved participants learning a series of emotional cue–target word pairs, before being presented with a subset of the cues and asked to either recall the associated target (think) or to prevent it from coming to mind (no think) by thinking about a substitute target word. Participants were subsequently asked to recall the targets to all cues (regardless of previous recall instructions). As expected, after controlling for anxiety, we found that dysphoric individuals exhibited impaired forgetting relative to the non-dysphoric participants. Also as expected, we found that superior working memory function was associated with more successful forgetting. Critically, in the dysphoric group, we found that working memory mediated the effect of depression on intentional forgetting. That is, depression influenced forgetting indirectly via its effect on working memory. However, under conditions of repeated suppression, there was also a direct effect of depression on forgetting. These findings represent an important development in the understanding of impaired forgetting in depression and also suggest that working memory training might be a viable intervention for improving the ability of depressed individuals to prevent unwanted memories from coming to mind.

The Interrelations of Physical and Mental Health: Self-Rated Health, Depression, and PTSD Among Female IPV Survivors.

Researchers have found that intimate partner violence (IPV) is associated with low self-rated health (SRH), which is correlated with increased medication usage, and has tremendous social consequences. IPV and low SRH are associated with posttraumatic stress disorder (PTSD) and depression, and the current study examined the interrelations between these variables among 505 Israeli women in shelters. To assess mediation, three regressions were designed. Traumatic events, Russian ethnicity, and chronic illness all contributed to low SRH. The direct effect of depression on SRH was insignificant when PTSD entered the regression. Our findings suggest that PTSD is a more fundamental factor than depression when predicting SRH among IPV survivors.

Maternal depressive symptoms and adolescent academic attainment: Testing pathways via parenting and self-control

Maternal depression is associated with reduced academic attainment in children, however, it is not clear how this association comes about. Depressive symptoms are associated with impairment in social roles including parenting. Children's self-control is an important contributor to academic attainment and is influenced by parenting. We therefore hypothesised that impaired parenting and children's self-control may mediate links between maternal depression and children's academic attainment. Data were from a brief longitudinal study (3 waves) of UK children aged 11–12 years and their mothers. Higher maternal depressive symptoms at baseline were associated with lower academic attainment in children assessed one year later. There was evidence to support an indirect effect of maternal depressive symptoms on children's academic attainment through the mother-child and the father-child relationship which, in turn, reduced children's self-control. These influences were independent of socio-economic deprivation. A direct effect of maternal depression on children's academic attainment was also observed.

Climacteric symptoms and their relation to feminine self-concept

Objectives: To investigate women’s subjective experiences in the climacteric transition, especially the impact of self-concept, quality of life and depression on the severity of climacteric symptoms.Method: Non-experimental, cross-sectional study, purpose sampling. To analyze the results, we proposed a three-way interaction, in which the direct effect of depression on the severity of climacteric symptoms would be buffered by perceived sexual quality of life, and mediated by self-concept.Results: As hypothesized, depression significantly predicted self-concept, which in turn mediated the severity of climacteric symptoms. In a second stage of the model, sexual quality of life moderated the direct effect of depression on climacteric symptoms, such that women with a better sexual quality of life would perceive less severity of climacteric symptoms than those with a less favorable sexual quality of life. Physical quality of life did not significantly buffer the direct effect of depression on climacteric symptoms, nor did vasomotor or psychosocial quality of life.Conclusions: Our study confirmed the impact of subjective factors such as satisfaction, self-concept, and quality of life on climacteric symptoms; specifically, we observed the moderating effect of the sexual quality of life on the previously established correlation between depression and aggravation of climacteric symptoms.

Longitudinal pathways from early maternal depression to children’s dysregulated representations: a moderated mediation analysis of harsh parenting and gender

ABSTRACTThere is some evidence linking maternal depression, harsh parenting, and children’s internal representations of attachment, yet, longitudinal examinations of these relationships and differences in the developmental pathways between boys and girls are lacking. Moderated mediation growth curves were employed to examine harsh parenting as a mechanism underlying the link between maternal depression and children’s dysregulated representations using a nationally-representative, economically-vulnerable sample of mothers and their children (n = 575; 49% boys, 51% girls). Dysregulation representations were measured using the MacArthur Story Stem Battery at five years of age (M = 5.14, SD = 0.29). Harsh parenting mediated the association between early maternal depression and dysregulated representations for girls. Though initial harsh parenting was a significant mediator for boys, a stronger direct effect of maternal depression to dysregulated representations emerged over time. Results are discussed in terms of their implications for intervention efforts aimed at promoting early supportive parenting.

Explaining risk for suicidal ideation in adolescent offspring of mothers with depression.

It is well-established that offspring of depressed mothers are at increased risk for suicidal ideation. However, pathways involved in the transmission of risk for suicidal ideation from depressed mothers to offspring are poorly understood. The aim of this study was to examine the contribution of potential mediators of this association, including maternal suicide attempt, offspring psychiatric disorder and the parent-child relationship. Data were utilized from a population-based birth cohort (ALSPAC). Three distinct classes of maternal depression symptoms across the first 11 years of the child's life had already been identified (minimal, moderate, chronic-severe). Offspring suicidal ideation was assessed at age 16 years. Data were analysed using structural equation modelling. There was evidence for increased risk of suicidal ideation in offspring of mothers with chronic-severe depression symptoms compared to offspring of mothers with minimal symptoms (odds ratio 3.04, 95% confidence interval 2.19-4.21). The majority of this association was explained through maternal suicide attempt and offspring psychiatric disorder. There was also evidence for an independent indirect effect via the parent-child relationship in middle childhood. There was no longer evidence of a direct effect of maternal depression on offspring suicidal ideation after accounting for all three mediators. The pattern of results was similar when examining mechanisms for maternal moderate depression symptoms. Findings highlight that suicide prevention efforts in offspring of depressed mothers should be particularly targeted at both offspring with a psychiatric disorder and offspring whose mothers have made a suicide attempt. Interventions aimed at improving the parent-child relationship may also be beneficial.

Depression, adherence and attrition from care in HIV-infected adults receiving antiretroviral therapy

BackgroundA better understanding of the relationship between depression and HIV-related outcomes, particularly as it relates to adherence to treatment, is critical to guide effective support and treatment of individuals with...

Direct and indirect effect of depression in adolescence on adult wages

It is well recognized that a depressive mental state can persist for a long time, and this can adversely impact labour market outcomes. The aim of this article is to examine the direct association between depression status in late-teenage years and adult wages, as well as the indirect association, operating through accumulated education, experience and occupation choice. Using the National Longitudinal Survey of Youth 1997 data, we find adolescent depression is associated with a wage penalty of around 10–15%, but its mechanics are very different for males and females. For males, about three quarters of the wage penalty is through the direct channel, whilst for females the indirect effect channel is dominant. The indirect channel is driven by lower accumulated education, mostly because depression discourages further study post high school. These results are important because they imply that the association between adolescent depression and wages is stronger than has been estimated in previous cross-sectional studies.

The relationships among depression, physical health conditions and healthcare expenditures for younger and older Americans

Background and aims: Little is known about the extent depression adds to the costs of treatment for physical health conditions. This study examined the paths and the extent to which depression in conjunction with a physical health problem is associated with an increase in healthcare expenditures and how that is different between younger and older adults.Methods: Data from the 2007 Medical Expenditure Panel Survey (MEPS) were analyzed. Depression status and physical health conditions were identified through ICD-9 codes. The multiple group structural equation modeling (SEM) was employed to examine the moderated mediation effects.Results: Approximately 11% of adults had clinical depression. The multiple group SEM for both younger and older adult groups supports not only a direct effect of depression on expenditures but also an indirect effect via comorbid health conditions. Furthermore, the indirect effect was significantly more prominent among older respondents than among younger ones, indicating significant moderated mediation by age.Conclusions: Depression has greater effects on comorbid health conditions and an increase in total healthcare expenditures through comorbid conditions among older adults. Findings of this study suggest that proper detection and treatment of depression is beneficial in reducing overall healthcare expenditures, especially among older adults.

Evaluation of polyherbal formulation (SJT-HT-03) for antihypertensive activity in albino rats.

Background:Hypertension is an incurable pathological condition and lifelong therapy is required. Long term use of conventional synthetic anti-hypertensive drugs is associated with a spectrum of toxic effects. However, therapeutic interventions using herbal drugs for hypertension have gained considerable attention worldwide.Aim:To evaluate the anti-hypertensive activity of polyherbal formulation (SJT-HT-03).Materials and Methods:The polyherbal formulation (SJT-HT-03) comprises of leaves of Aegle marmelos L., fruits of Benincasa hispida Thunb., Garcinia indica Thouars, and flowers of Musa paradiasica L., Rosa indica L., Hibiscus rosa sinensis L. Selected plants as mentioned above were collected, dried and extracted with different solvents. Formulation SJT-HT-03 (250 mg/kg, p.o.), was evaluated using two kidney one clip (2K1C) model and deoxycorticosterone acetate (DOCA)-salt-induced hypertension model using the enalapril (10 mg/kg, p.o.) and hydrochlorothiazide (5 mg/kg, p.o.) as a reference standard drug in respective models.Results:SJT-HT-03 significantly reduced (P < 0.001, one-way analysis of variance followed by Turkey's multiple comparison tests) systolic as well as diastolic blood pressure (BP) in 2K1C and DOCA-salt model. Further, SJT-HT-03 has shown a significant reduction (P < 0.01) in angiotensin converting enzyme (ACE) activity in serum, clipped kidney as well as in lungs in 2K1C model, whereas significant reduction (P < 0.05) in serum Na+ and increase in serum K+ level in DOCA model.Conclusion:Polyherbal formulation SJT-HT-03 possess significant anti-hypertensive activity by producing direct depressant effect on heart, inhibition of ACE, aldosterone antagonistic as well as diuretic effect and thereby act on multiple targets to achieve optimal effect.

Insomnia, depression and subtypes of anxiety: does chronotype uniquely mediate these relationships during adolescence?

This study investigated the direct effect of depression and subtypes of anxiety on insomnia, and vice-versa, and the unique mediation effect of chronotype. Self-report questionnaires were completed by 318 South Australian high school students from years 7 to 11 (range 12–18, mean 14.96 ± 1.34 ). Insomnia was assessed by the Insomnia Severity Index. Depression, anxiety and subtypes of anxiety were assessed by the Revised Child Anxiety and Depression Scale, and chronotype was assessed by the Morningness-Eveningness Questionnaire for Children. Generalised Estimating Equations were used to assess direct and indirect effects, which provided confidence intervals (CI) for direct and indirect effects. The proposed mediators for the relationship between insomnia and subtypes of anxiety were chronotype and depression, while the proposed mediators for the relationship between insomnia and depression were chronotype and anxiety. Insomnia predicted depression ( β = 0.3765 , 95%CI = 0.603–0.788) after the mediation variables were accounted for, whereas insomnia was predicted by depression and GAD (depression, β = 0.5255 , 95%CI = 0.406–0.645; GAD, β = 0.180 , 95%CI = 0.025–0.336). Insomnia was found to directly predict panic disorder (PD) ( β = 0.064 , 95%CI = 0.007–0.121), but not vice-versa. However, it is likely this result was due to a type II error. Obsessive compulsive disorder (OCD), separation anxiety (SAD) or social phobia (SP) were not significantly related to insomnia. The eveningness chronotype uniquely mediated the models where depression and PD predicted insomnia (Depression β = 0.0823 , 95%CI = 0.043–0.121; PD β = - 0.0551 , 95%CI = 0.022–0.09) and vice versa (Depression β = 0.0553 , 95%CI = 0.029–0.082; PD β = - 0.026 , 95%CI = −0.049–0.002). Eveningness also uniquely mediated the models when insomnia was predicted by OCD ( β = 0.0646 , 95%CI = 0.009–0.120), SAD ( β = 0.067 , 95%CI = 0.027–0.107) and SP ( β = 0.0406 , 95%CI = 0.0169–0.064). The results indicate that insomnia directly predicts depression and is predicted by depression and GAD after controlling for mediators, but not other forms of anxiety. Chronotype was found to be a unique mediator for most analyses, but the mediation effects were of small magnitude. This suggests that chronotype partially accounts for the relationship between insomnia and depression, and insomnia and subtypes of anxiety above and beyond anxiety and depression. However, anxiety and depression are likely to have a much stronger mediation effect than chronotype. Authors did not have conflict of interests, including specific financial interests and relationships and affiliations relevant to the subject of this manuscript. The principal author ”had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.”

Maternal depression and the intergenerational transmission of relational impairment.

Previous research has demonstrated that the offspring of depressed mothers are at greater risk for negative psychopathological and psychosocial outcomes than children of nondepressed mothers. This study specifically examines offspring's romantic relationship quality during the transition to adulthood as a function of maternal depression and 3 putative mechanisms for this association: youth depression history, mother-child relationship discord, and maternal romantic relationship difficulties. The study further explores the role of these factors in the risk for depressive symptoms during the transition to adulthood. Hypotheses were examined longitudinally in a community sample of 182 Australian youth who were followed from birth to age 20 and were in committed romantic relationships at age 20 with romantic partners willing to provide data regarding romantic relationship satisfaction. Structural equation modeling analyses found support for a direct effect of maternal depression on youth romantic relationship quality with significant mediation by mother-child relationship discord, as well as an association between mother-child relationship discord and later depressive symptoms that is mediated by youth romantic relationship quality. Findings also lend support for an indirect effect of maternal depression on youth depressive symptoms via mother-child relationship discord and youth romantic relationship quality. This study provides further evidence for the negative psychosocial and psychopathological outcomes of children of depressed mothers and the intergenerational transmission of relational difficulties.

Applications of Nitrous Oxide for Procedural Sedation in the Pediatric Population

The objective of this review was to provide a general descriptive account of the physical properties, end-organ effects, therapeutic applications, and delivery techniques of nitrous oxide (N2O) as used in the arena of procedural sedation. A computerized bibliographic search regarding the applications of nitrous for provision of sedation and analgesia during procedures with an emphasis on the pediatric population was performed. The end-organ effects of N2O have been well described in the operating room setting. Aside from its effects on the central nervous system of sedation and analgesia, N2O may alter intracerebral dynamics and alter cerebral blood flow and intracranial pressure especially in patients with altered intracranial compliance. Effects on ventilation include a dose-related depression of ventilatory function and control of upper airway patency. These effects are generally limited in the absence of comorbid diseases and potentiated by other sedative and analgesic agents. The more clinically significant respiratory effect of N2O on ventilatory function is a dose-dependent depression of the ventilatory response to hypoxemia. Hemodynamic effects include a mild direct depressant effect on myocardial function, which in the absence of comorbid cardiac disease is generally compensated by stimulation of the sympathetic nervous system. Nitrous oxide may potentially aggravate pulmonary hypertension. Additional physiologic effects on neurologic and hematologic function may result in inactivation of the enzyme, methionine synthetase. Recent concern has also been raised regarding the potential effects of N2O on immune function and its relationship to perioperative surgical site infections. Given differences in the solubility, N2O will diffuse into and significantly expand gas-filled cavities. Chronic exposure of health care works to N2O is also a concern. Although there are limited data in the literature to clearly substantiate concerns regarding the reproductive toxicity of occupational exposure to N2O, appropriate scavenging and use of other techniques are mandatory. Nitrous oxide has been shown to be effective for a variety of minor surgical procedures such as venipuncture, intravenous cannula placement, lumbar puncture, bone marrow aspiration, laceration repair, dental care, and minor dermatologic procedures. It is generally as effective as midazolam, with several studies demonstrating it to be more effective. However, its utility is not as great in severely painful procedures such as fracture reduction. Demonstrated advantages to parenteral sedation include a more rapid onset and a shorter recovery time with the majority of patients preferring it to over other agents or agreeing to its use for subsequent procedures. The literature also suggests increased success rates with simple procedures such as intravenous cannula placement when compared with placebo. In general, life-threatening adverse events have not been reported. Most common adverse effects include dysphoria and vomiting. For more painful procedures, combination with another agent may be used, and in all cases, topical or infiltrative local anesthesia is recommended. In general, N2O is a useful adjunct for procedural sedation. Given the variety of procedures performed in the pediatric patient, ongoing research is required to identify the most appropriate and effective use of this agent. This may be particularly relevant when evaluating its use for procedures associated with significant pain. In these scenarios, the combination of N2O with other agents needs to be evaluated. Given the potential for adverse effects, strict adherence to published guidelines regarding procedural sedation and monitoring is suggested.

Maternal psychological functioning and children's school readiness: The mediating role of home environments for African American children

Decades of educational research has documented an achievement gap in kindergarten reading and math achievement between African American children and their European American counterparts. Research has also shown that specific parenting practices (e.g., home literacy involvement) have the potential to narrow school readiness gaps by at least half. The current study examined whether and how maternal depression and parenting stress may influence specific parenting practices, as well as whether maternal warmth, home learning stimulation and cultural socialization mediated the relation between maternal depression, parenting stress, and children's kindergarten reading and math achievement. Path analyses revealed a direct negative effect of maternal depression and parenting stress on maternal warmth, home learning stimulation, and cultural socialization. Home learning stimulation emerged as an important mediator between maternal parenting stress and math achievement. Further, maternal warmth mediated the relation between maternal depression and reading achievement. Implications for early childhood research, practice and policy are discussed.

Factors affecting the quality of life of middle‐aged women suffering Hwa‐Byung

To test a staged theoretical model designed to explain causal relationships affecting the quality of life (QOL) of middle-aged Korean women suffering from Hwa-Byung (HB). The model contains three stages comprised of antecedents (stage 1), perception (stage 2) and outcome variable (stage 3). Stage 1 contains individual characteristic and emotional distress variables. In stage 2, the perception variable is depression (DEP). In stage 3, the outcome factor is QOL. Design. A cross-sectional, descriptive design was used. A convenience sample of 135 community dwelling middle-aged women was recruited over a five-month period in the neuropsychology outpatient clinic at an Oriental hospital in Korea. The instruments were the Korean version of WHO Quality of Life-BREF (WHOQOL-BREF), Korean version of State-Trait Anger Expression Inventory (STAXI-K), The Korean version of State-Trait Anxiety Inventory (STAI-K) and Korean version of Beck Depression Inventory (K-BDI). Forty-five per cent of the variance in the QOL of women with HB was explained by the direct effect of depression (β = -0·356, p = 0·000) and trait anxiety (β = -0·324, p = 0·001). State anger (β = 0·429, p = 0·000) and spouse (β = -0·180, p = 0·021) explained 45·0% of the variance in (of) depression. The findings showed that depression mediates the relationship between the emotional distress and QOL as a negative outcome. These relationships can guide researchers and psychiatric mental health nurses to understand depression as a mediating factor and to develop nursing interventions to improve QOL of HB women.

Effects of Antidepressants, but not Psychopathology, on Cardiac Sympathetic Control: A Longitudinal Study

Increased sympathetic activity has been hypothesized to have a role in the elevated somatic disease risk in persons with depressive or anxiety disorders. However, it remains unclear whether increased sympathetic activity reflects a direct effect of anxiety or depression or an indirect effect of antidepressant medication. The aim of this study was to test longitudinally whether cardiac sympathetic control, measured by pre-ejection period (PEP), was increased by depression/anxiety status and by antidepressant use. Cross-sectional and longitudinal data were from a depression and anxiety cohort: the Netherlands Study of Depression and Anxiety (NESDA). Baseline data of 2838 NESDA subjects (mean age 41.7 years, 66.7% female) and 2-year follow-up data of 2226 subjects were available for analyses. Included were subjects with and without depressive/anxiety disorders, using or not using different antidepressants at baseline or follow-up. The PEP was measured non-invasively by 1.5 h of ambulatory impedance cardiography. Cross-sectional analyses compared PEP across psychopathology and antidepressant groups. Longitudinal analyses compared 2-year changes in PEP in relation to changes in psychopathology and antidepressant use. Cross-sectional analyses showed that antidepressant-naïve depressive/anxious subjects had comparable PEP as controls, whereas subjects using tricyclic (TCA) or combined serotonergic/noradrenergic antidepressants (SNRI) had significantly shorter PEP compared with controls. In contrast, subjects using selective serotonin re-uptake inhibitors (SSRIs) had longer PEP than controls. Longitudinal results confirmed these findings: compared with 2-year change in PEP in continuous non-users (+2 ms), subjects who started TCA or SNRI treatment showed significantly shortened PEP (-11 ms, p=0.005 and p<0.001), whereas subjects who started SSRI treatment showed significant prolongation of PEP (+9 ms, p=0.002). Reversed findings were observed among those who stopped antidepressant use. These findings suggest that depressive and anxiety disorders are not associated with increased cardiac sympathetic control. However, results pose that TCA and SNRI use increases sympathetic control, whereas SSRI use decreases sympathetic control.

A note on the pharmacology of rescinnamine and serpentine.

Abstract The pharmacological properties of rescinnamine and serpentine have been studied. Both lower the blood pressure of anaesthetised cats but rescinnamine has a prolonged effect whilst serpentine has only a brief action. Rescinnamine does not antagonise the effects of adrenaline or noradrenaline on the blood pressure of the cat or on the isolated heart, auricles or intestine. Serpentine antagonises vasoconstriction due to adrenaline and noradrenaline in the isolated perfused rat hindquarters but not that due to 5-hydroxytryptamine creatine sulphate, barium chloride or pitressin. Serpentine reversibly antagonises the pressor responses to bilateral carotid occlusion, central vagal stimulation and splanchnic stimulation. Rescinnamine irreversibly antagonises these responses and also the responses from compression of the abdominal aorta and hypoxia, which suggests both alkaloids have an action upon the sympathetic nervous system. Rescinnamine also has some direct depressant effects on cardiac, intestinal and skeletal muscle.

Controlled ovarian hyperstimulation--an inflammatory state.

Controlled ovarian hyperstimulation (COH) is apparently a key factor in the success of in vitro fertilization-embryo transfer. One of the major complications of COH is severe ovarian hyperstimulation syndrome (OHSS), which may be attributable to a massive increase in systemic inflammatory cytokines or to neutrophil activation. The aim of the present review was to investigate the role of COH in the induction of an inflammatory response. Major studies that have reported on the association between COH and inflammation were identified through MEDLINE searches and the published literature. Several inflammatory mediators, namely, C-reactive protein and leukocyte and endothelial selectins, showed a significant increase after human chorionic gonadotropin (hCG) administration in vivo, reflecting an inflammatory state, and neutrophil and endothelial activation, respectively. On the other hand, hCG showed a direct depressive effect on mononuclear cells in vitro. Because the development of OHSS almost always follows hCG administration, the negative effect of hCG on peripheral mononuclear cells indicates that it probably causes OHSS by an indirect mechanism. We suspect that hCG stimulates the ovaries to produce and secrete a still unknown intermediate factor, which in turn activates inflammatory processes that may lead to an increase in capillary permeability.

The effect of remifentanil on the middle latency auditory evoked response and haemodynamic measurements with and without the stimulus of orotracheal intubation

Background and objective: Changes in the middle latency auditory evoked response following the administration of opioids have been shown. However, it remains unclear as to whether these changes are due to a direct depressant effect of opioids on the middle latency auditory evoked response itself, or an indirect effect on account of their action in attenuating central nervous system arousal associated with noxious stimuli. By comparing changes in the middle latency auditory evoked response in intubated and non-intubated patients, receiving saline or remifentanil in different doses, this study attempts to answer this question. Methods: Fifty-four patients were anaesthetized with isoflurane and nitrous oxide (0.9 MAC) and randomized to 1-6 groups. Groups 1-3 received a bolus injection of either saline 0.9%, low-dose remifentanil (1 μg kg−1) or high-dose remifentanil (3 μg kg−1) prior to intubation of the trachea. Groups 4-6 were not intubated following the bolus injection. Results: Pa and Nb amplitudes of the middle latency auditory evoked response increased by 82% and 79% with intubation in the saline group (P < 0.005) and these changes were not seen in the patients given remifentanil. There was a significant linear trend for the reduction in Pa and Nb amplitude with increasing remifentanil dose (P < 0.05). In the absence of endotracheal intubation remifentanil had no effect on either the amplitudes or latencies of the waves Pa and Nb and there was no effect of dose. For the haemodynamic measurements remifentanil attenuated the pressor response to intubation (P < 0.001) and had a significant dose-related effect (P < 0.001) in the absence of intubation. Conclusions: We demonstrated an effect of remifentanil on both the middle latency auditory evoked response and haemodynamic changes to endotracheal intubation. For the non-intubated patients there was only an effect of remifentanil on the haemodynamic measurements. This suggests that remifentanil has an effect on the middle latency auditory evoked response in attenuating the arousal associated with intubation of the trachea but has no effect in the absence of a stimulus.

Direct myocardial depressant effect of methylmethacrylate monomer: mechanical and electrophysiologic actions in vitro.

The present study explored the mechanism of direct myocardial depression by methylmethacrylate monomer (MMA). Isometric contraction of isolated guinea pig right ventricular papillary muscle was measured in modified normal and 26 mm K+ Tyrode solutions at various stimulation rates. Normal and slow action potentials were evaluated by conventional microelectrode technique. MMA effects on various aspects of sarcoplasmic reticulum function were evaluated by its effect on rapid-cooling contractures, rested-state contraction in rat papillary muscle in modified normal Tyrode solution, and in guinea pig papillary muscle under low Na+ (25 mm) Tyrode solution. Whole cell patch clamp techniques were applied to measure the inward Ca2+ currents (I(Ca)). MMA (0.5, 1.5, and 4.7 mm) caused concentration-dependent depression of peak force and maximal rate of force development to approximately 70, 50, and 20% of baseline from rested state to 3 Hz stimulation rates, respectively. Depression of peak force and maximal rate of force development by MMA was dependent on stimulation frequency, with less depression at higher stimulation rates. In low Na+ Tyrode solution, 1.5 mm MMA depressed peak force of rat and guinea pig myocardium by 20-30%. In 26 mm K+ Tyrode solution, 0.5 and 1.5 mm MMA caused selective and marked concentration-dependent depression of late force development (0.5 mm: approximately 60% of baseline, 1.5 mm: approximately 30% of baseline) with no alteration in early force development. MMA (1.5 mm) depressed rapid-cooling contracture to 53 +/- 10% of baseline, accompanied by approximately 63% prolongation of time to peak contracture. In patch clamp studies, MMA reduced I(Ca) in a concentration-dependent manner. The direct myocardial depressant effect of MMA seems to be caused in part by depression of Ca2+ influx through cardiac membrane, while depolarization-activated sarcoplasmic reticulum Ca2+ release appears modestly depressed.