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Biomedical subjects

E M Kaplan

Publications and source records attributed to E M Kaplan.

8 recordsLinked to original sources
PubMed1997

Serotonin reuptake inhibitor discontinuation syndrome: a hypothetical definition. Discontinuation Consensus panel.

Adverse events following discontinuation from serotonin reuptake inhibitors (SRIs) are being reported in the literature with increasing frequency; the frequency and severity of these symptoms appear to vary according to the half-life of the SRI, e.g., the incidence appears higher with the shorter half-life agents than with fluoxetine, which has an extended half-life. Yet, there have been no systematic studies of the phenomenon to date. Therefore, a group of experts convened in Phoenix, Arizona, to develop a clear description or definition of the phenomenon based on these reports. The SRI discontinuation syndrome, referred to as "withdrawal symptoms" in many anecdotal case reports, is distinctly different from the classic withdrawal syndrome associated with alcohol and barbiturates. Anti-depressants are not associated with dependence or drug-seeking behavior. SRI discontinuation symptoms tend to be short-lived and self-limiting, but can be troublesome. They may emerge when an SRI is abruptly discontinued, when doses are missed, and less frequently, during dosage reduction. In addition, the symptoms are not attributable to any other cause and can be reversed when the original agent is reinstituted, or one that is pharmacologically similar is substituted. SRI discontinuation symptoms, in most cases, may be minimized by slowly tapering antidepressant therapy, but there have been several case reports where symptoms occurred consistently even through repeated attempts to taper therapy. Physical symptoms include problems with balance, gastrointestinal and flu-like symptoms, and sensory and sleep disturbances. Psychological symptoms include anxiety and/or agitation, crying spells, and irritability. Further analyses of data bases and clinical studies are needed to define this proposed syndrome more clearly.

Depressive Disorder↗
PubMed1997

Possible biological mechanisms of the serotonin reuptake inhibitor discontinuation syndrome. Discontinuation Consensus Panel.

Although the number of documented serotonin reuptake inhibitor (SRI) discontinuation reactions is increasing, to date no systematic studies have been completed; therefore the mechanism of action for these reactions is not clearly understood. However, several hypotheses have been proposed. Researchers have postulated that discontinuation events result from a sudden decrease in the availability of synaptic serotonin in the face of down-regulated serotonin receptors. In addition, other neurotransmitters, such as dopamine, norepinephrine, or gamma-aminobutyric acid (GABA), may also be involved, although little research in this area has been published. Individual patient sensitivity, i.e., genetics or cognitive mindset, may also be a factor in SRI discontinuation phenomena. Finally, experts have hypothesized that since some symptoms associated with paroxetine withdrawal are similar to those of tricyclic antidepressant discontinuation, they may be caused by cholinergic rebound.

Down-Regulation↗
PubMed1997

Antidepressant noncompliance as a factor in the discontinuation syndrome.

Compliance is generally defined as the extent to which a patient adheres to a treatment regimen and, specifically, takes medication as prescribed. While little research is available about the number of patients who consistently skip antidepressant doses, the literature indicates that about 30% of patients discontinue treatment suddenly within the first month. Both missed doses and abrupt stoppage of treatment place a patient at risk for experiencing discontinuation symptoms. A variety of reasons ranging from forgetfulness to lack of knowledge about the importance of taking every dose may lead to nonadherence to an antidepressant regimen. By spending time on patient education, providing reasons why patients should take every antidepressant dose, discussing alternative treatments, and conveying empathy, support for, and understanding of the patient, physicians may be able to minimize noncompliance and consequently decrease the likelihood that a patient may experience discontinuation symptoms. Discontinuation of an antidepressant can cause a patient to be irritable, experience severe dizziness, or act emotionally absent, which may have a sustained adverse impact both on job performance and on family and social relationships.

Antidepressive Agents↗
PubMed1991

Ca(2+)-independent F-actin assembly and disassembly during Fc receptor-mediated phagocytosis in mouse macrophages.

Phagocytosis of IgG-coated particles by macrophages is presumed to involve the actin-based cytoskeleton since F-actin accumulates beneath forming phagosomes, and particle engulfment is blocked by cytochalasins, drugs that inhibit actin filament assembly. However, it is unknown whether Fc receptor ligation affects the rate or extent of F-actin assembly during phagocytosis of IgG-coated particles. To examine this question we have used a quantitative spectrofluorometric method to examine F-actin dynamics during a synchronous wave of phagocytosis of IgG-coated red blood cells by inflammatory mouse macrophages. We observed a biphasic rise in macrophage F-actin content during particle engulfment, with maxima at 1 and 5 min after the initiation of phagocytosis. F-actin declined to resting levels by 30 min, by which time particle engulfment was completed. These quantitative increases in macrophage F-actin were reflected in localized changes in F-actin distribution. Previous work showed that the number of IgG-coated particles engulfed by macrophages is unaffected by buffering extracellular calcium or by clamping cytosolic free calcium concentration ([Ca2+]i) to very low levels (Di Virgilio, F., B. C. Meyer, S. Greenberg, and S. C. Silverstein. 1988. J. Cell Biol. 106: 657-666). To determine whether clamping [Ca2+]i in macrophages affects the rate of particle engulfment, or the assembly or disassembly of F-actin during phagocytosis, we examined these parameters in macrophages whose [Ca2+]i had been clamped to approximately less than 3 nM with fura 2/AM and acetoxymethyl ester of EGTA. We found that the initial rate of phagocytosis, and the quantities of F-actin assembled and disassembled were similar in Ca(2+)-replete and Ca(2+)-depleted macrophages. We conclude that Fc receptor-mediated phagocytosis in mouse macrophages is accompanied by an ordered sequence of assembly and disassembly of F-actin that is insensitive to [Ca2+]i.

Actin Cytoskeleton↗