203 resultados para insulated gate bipolar transistor (IGBT)


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Objectives: To review the current knowledge of bipolar II disorder.

Methods: Literature was reviewed after conducting a Medline search and a hand search of relevant literature.

Results: Bipolar II disorder is a common disorder, with a prevalence of approximately 3–5%. Distinct clinical features of bipolar II disorder have been described. The key to diagnosis is the recognition of past hypomania, while depression is the typical presenting feature of the illness. This is responsible for a significant rate of missed diagnosis, and consequent management according to unipolar guidelines. It is unclear if bipolar II disorder is over-represented amongst resistant depression populations and if abrupt offset of antidepressant action is a phenomenon over represented in bipolar II disorder, reflecting induction of predominantly depressive cycling. A few mood-stabilizer studies available provide provisional suggestion of utility. A supportive role for psychosocial therapies is suggested, however, there is a sparsity of published studies specific to bipolar II disorder cohorts. A small number of short-term antidepressant trials have suggested efficacy, however, compelling long-term maintenance data is absent.

Conclusions: An emerging literature on the specific clinical signature and management of the disorder exists, however, this is disproportionately small relative to the epidemiology and clinical significance of the disorder.

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Bipolar disorder is a severe and recurrent disorder. Atypical antipsychotics have emerged as both an alternative and adjunct to conventional mood stabilisers. The manic phase of the illness is the best studied, and it appears that a class effect with regards to efficacy is present in both monotherapy and augmentation studies. Evidence for efficacy of atypical antipsychotics in depression is emerging. At this stage controlled data are available for both olanzapine and quetiapine. Maintenance data demonstrating efficacy are available for olanzapine. Atypical antipsychotics have utility in treating acute agitation and aggression in manic episodes of bipolar disorder. Subgroup analyses from trials treating manic phase bipolar disorder, and an open-label study of rapid cycling, have suggested that atypical antipsychotics may be useful for the treatment of mixed states and rapid cycling. Several studies have suggested that atypical antipsychotics may be useful in treatment-refractory episodes of bipolar disorder. The current available data suggest greater efficacy of the atypical antipsychotics in mania than in depression, although the data are fairly clear that induction of depression is not an issue with the atypical antipsychotics. A number of trials are underway that will hopefully address many of the questions still pending.

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Recent evidence suggests that the prevalence of bipolar disorder is as much as fivefold higher than previously believed, and may amount to nearly 5% of the population, making it almost as common as unipolar major depression. It is, therefore, not unrealistic to assume that primary care or family physicians will frequently encounter bipolar patients in their practice. Such patients may present with a depressive episode, for a variety of medical reasons, for longer-term maintenance after stabilization, and even with an acute manic episode. Whatever the reason, a working knowledge of current trends in the acute and longer-term management of bipolar disorder would be helpful to the primary care physician. In addition, an understanding of important side-effects and drug interactions that occur with drugs used to treat bipolar disorder, which may be encountered in the medical setting, are paramount. This paper will attempt to review existing and emerging therapies in bipolar disorder, as well as their common drug interactions and side-effects.

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Background: The phenomenology of unipolar and bipolar disorders differ in a number of ways, such as the presence of mixed states and atypical features. Conventional depression rating instruments are designed to capture the characteristics of unipolar depression and have limitations in capturing the breadth of bipolar disorder.

Method: The Bipolar Depression Rating Scale (BDRS) was administered together with the Montgomery Asberg Rating Scale (MADRS) and Young Mania Rating Scale (YMRS) in a double-blind randomised placebo-controlled clinical trial of N-acetyl cysteine for bipolar disorder (N = 75).

Results: A factor analysis showed a two-factor solution: depression and mixed symptom clusters. The BDRS has strong internal consistency (Cronbach's alpha = 0.917), the depression cluster showed robust correlation with the MADRS (r = 0.865) and the mixed subscale correlated with the YMRS (r = 0.750).

Conclusion: The BDRS has good internal validity and inter-rater reliability and is sensitive to change in the context of a clinical trial.

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Objective: To explore diagnostic and treatment issues concerning bipolar mixed states.

Method: Bipolar mixed states are described and concerns about diagnostic and treatment difficulties are summarized and discussed.

Result: Mixed states can present with equal admixtures of depressive or manic symptoms, or more commonly one component predominates. There is fair consensus, although little data, regarding the management of manic mixed states. However depressive mixed states are far more complex both in terms of recognition and management. People suffering from mixed states characteristically present with complaints of depression.

Conclusions: The boundaries between depressive mixed states and agitated depression are vague, yet carry substantial therapeutic implications. Bipolar mixed states are often difficult to treat, and tend to take much longer to settle than either pure mania or depression.  Furthermore there is data that treatment with antidepressants can worsen the course of mixed states. Hence missed diagnoses can potentially have negative clinical implications.  Therefore in this paper the clinical presentation, diagnosis and therapy of mixed states is reviewed with a view to improving management.

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Objective: Rational therapeutic development in bipolar is hampered by a lack of pathophysiological model. However, there is a wealth of converging data on the role of dopamine in bipolar disorder. This paper therefore examines the possibility of a dopamine hypothesis for bipolar disorder.

Method: A literature search was conducted using standard search engines Embase, PyschLIT, PubMed and MEDLINE. In addition, papers and book chapters known to the authors were retrieved and examined for further relevant articles.

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Collectively, in excess of 100 articles were reviewed from which approximately 75% were relevant to the focus of this paper.

Conclusion: Pharmacological models suggest a role of increased dopaminergic drive in mania and the converse in depression. In Parkinson’s disease, administration of high-dose dopamine precursors can produce a ‘maniform’ picture, which switches into a depressive analogue on withdrawal. It is possible that in bipolar disorder there is a cyclical process, where increased dopaminergic transmission in mania leads to a secondary down regulation of dopaminergic receptor sensitivity over time. This may lead to a period of decreased dopaminergic transmission, corresponding with the depressive phase, and the repetition of the cycle. This model, if verified, may have implications for rational drug development.

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Bipolar disorder has a major deleterious impact on many aspects of a patient's functioning and health-related quality of life. Although the formal measurement of these deficits has been neglected until recently, many well-designed trials now include an assessment of functioning and health-related quality of life using one or more rating scales. This review describes recent developments in the measurement of functioning and health-related quality of life in bipolar disorder, and discusses the evidence that medications that improve symptoms in bipolar disorder also offer clinically relevant benefits in functioning and health-related quality of life. Direct comparisons of the benefits of medications including atypical antipsychotics are problematic due to differences in trial populations, study durations and rating scales. Data from quetiapine trials indicate that this medication offers prompt and sustained improvement of functioning in patients with mania and enhancement of health-related quality of life in patients with bipolar depression, to accompany the significant improvements in mood episodes.