Dynamics of signaling between Ca(2+) sparks and Ca(2+)- activated K(+) channels studied with a novel image-based method for direct intracellular measurement of ryanodine receptor Ca(2+) current.

Ca(2+) sparks are highly localized cytosolic Ca(2+) transients caused by a release of Ca(2+) from the sarcoplasmic reticulum via ryanodine receptors (RyRs); they are the elementary events underlying global changes in Ca(2+) in skeletal and cardiac muscle. In smooth muscle and some neurons, Ca(2+) sparks activate large conductance Ca(2+)-activated K(+) channels (BK channels) in the spark microdomain, causing spontaneous transient outward currents (STOCs) that regulate membrane potential and, hence, voltage-gated channels. Using the fluorescent Ca(2+) indicator fluo-3 and a high speed widefield digital imaging system, it was possible to capture the total increase in fluorescence (i.e., the signal mass) during a spark in smooth muscle cells, which is the first time such a direct approach has been used in any system. The signal mass is proportional to the total quantity of Ca(2+) released into the cytosol, and its rate of rise is proportional to the Ca(2+) current flowing through the RyRs during a spark (I(Ca(spark))). Thus, Ca(2+) currents through RyRs can be monitored inside the cell under physiological conditions. Since the magnitude of I(Ca(spark)) in different sparks varies more than fivefold, Ca(2+) sparks appear to be caused by the concerted opening of a number of RyRs. Sparks with the same underlying Ca(2+) current cause STOCs, whose amplitudes vary more than threefold, a finding that is best explained by variability in coupling ratio (i.e., the ratio of RyRs to BK channels in the spark microdomain). The time course of STOC decay is approximated by a single exponential that is independent of the magnitude of signal mass and has a time constant close to the value of the mean open time of the BK channels, suggesting that STOC decay reflects BK channel kinetics, rather than the time course of [Ca(2+)] decline at the membrane. Computer simulations were carried out to determine the spatiotemporal distribution of the Ca(2+) concentration resulting from the measured range of I(Ca(spark)). At the onset of a spark, the Ca(2+) concentration within 200 nm of the release site reaches a plateau or exceeds the [Ca(2+)](EC50) for the BK channels rapidly in comparison to the rate of rise of STOCs. These findings suggest a model in which the BK channels lie close to the release site and are exposed to a saturating [Ca(2+)] with the rise and fall of the STOCs determined by BK channel kinetics. The mechanism of signaling between RyRs and BK channels may provide a model for Ca(2+) action on a variety of molecular targets within cellular microdomains.

The effects of agonist stimulation and beta(2)-adrenergic receptor level on cellular distribution of gs(alpha) protein.

This study examines the effects of adrenergic ligands, cholera toxin, forskolin, and varying levels of beta(2) adrenergic receptors (beta(2)AR) on the cellular distribution of Gs(alpha) subunits in CHO cells. Localization of Gs(alpha) was evaluated by confocal microscopy and beta(2)AR-mediated signalling was assessed by adenylyl cyclase (AC) activity. In cells expressing 0.2 pmol/mg protein beta(2)ARs (WT18), the localization of Gs(alpha) subunit was restricted to the plasma membrane region. Isoproterenol (ISO), cholera toxin or forskolin elicited redistribution of cellular Gs(alpha) so that Gs(alpha) appeared as intense spots throughout the plasma membrane as well as the cytoplasm. Exposure to a neutral beta(2)AR antagonist, alprenolol, prevented the ISO-stimulated Gs(alpha) translocation from peripheral to inner cytoplasm. In cells expressing high level of beta(2)ARs (8.2 pmol/mg) (WT4), basal and ISO-stimulated AC activities were significantly elevated when compared to the values detected in WT18 clone, suggesting a positive correlation between receptor expression and receptor-mediated signalling. Basal Gs(alpha) distribution in this group was similar to that observed in ISO-, cholera toxin-, or forskolin-stimulated WT18 clone. ISO, cholera toxin, or forskolin did not change the distribution of Gs(alpha) significantly when tested in WT4 clone. No difference in the cellular level of Gs(alpha) protein between WT18 and WT4 clones was detected. Alprenolol did not affect the distribution of Gs(alpha) in WT4 clone. ICI 118,551, a negative beta(2)AR antagonist, altered Gs(alpha) distribution from a dispersed basal pattern to a membrane-confined pattern. The latter appearance was similar to that observed in unstimulated WT18 clone. Taken together, these data suggest that: (1) enhanced beta(2)AR-Gs(alpha) coupling induced by agonist stimulation or by increased expression of beta(2)ARs remodel the cellular distribution of Gs(alpha); (2) the alteration in Gs(alpha) distribution induced by beta(2)AR overexpression provides evidence for agonist-independent interaction of beta(2)AR and Gs(alpha), that can be inhibited by a negative antagonist but not by a neutral antagonist; and (3) forskolin influences the activity state of Gs(alpha) that displays a Gs(alpha) distribution pattern comparable to that observed when Gs(alpha) is activated via beta(2)AR stimulation or directly by cholera toxin.

MRI changes associated with partial status epilepticus.

Neurological disorders of different etiology may cause identical clinical symptoms requiring additional diagnostic procedures for a precise differential diagnosis. Focal epileptic seizures have been shown to cause increased signal intensities in T2 and diffusion-weighted magnetic resonance images (MRI), mimicking other neurological disorders or diseases such as viral encephalitis. In some cases even the combination of neuroimaging and cerebrospinal fluid (CSF) analysis is not sufficient to obtain the final diagnosis, since epileptic seizures may cause pleocytosis as well. Some epilepsy centers presented cases of focal status epilepticus with severe but reversible MRI changes. These cases indicate that MRI-changes following focal seizures are reversible over a different time window compared to MRI changes associated with other etiologies, such as viral infection. This data further suggest that in cases where focal seizures can not be ruled out, a follow-up MRI scan within a few days following the onset of symptoms significantly improves the precision of the differential diagnosis. Recently new scientific data were reported in this review.

Effect of combination of misoprostol and indomethacin on eicosanoid production in carrageenan-induced air pouch inflammation in rats.

The effect of single or combined administration of indomethacin and misoprostol on the exudate leukocyte count and thromboxane B2, a stable metabolite of thromboxane A2, and on the leukotriene B4 level, as cyclooxygenase and lipoxygenase metabolites of arachidonic acid, was investigated in acute carrageenan-induced air pouch inflammation in rats. Administration of indomethacin (0.25 to 4 mg/kg) 1 h before carrageenan given by the orogastric route reduced the exudate leukocyte count and thromboxane B2 level whereas it increased the exudate leukotriene B4 level dose dependently. Administration of misoprostol, a synthetic prostaglandin E1 analogue, (12.5 to 100 microg/kg) twice daily for two days before carrageenan given by the orogastric route increased the exudate leukocyte count. Combined misoprostol and indomethacin did not change the effect of indomethacin alone on exudate leukocyte count. Misoprostol, when used alone, decreased exudate thromboxane B2 level significantly. However, misoprostol did not change the exudate leukotriene B4 level, while its combination with indomethacin prevented the indomethacin-induced increase in exudate leukotriene B4 level. In conclusion, although misoprostol can be combined with non-steroidal anti-inflammatory drugs in many chronic inflammatory situations, our results indicate that misoprostol may also be combined with indomethacin in acute inflammation without producing any change on the antiinflammatory efficacy of indomethacin in rats.

Psychological factors in the irritable bowel syndrome.

OBJECTIVE: The role of psychological factors in the irritable bowel syndrome (IBS) is a matter of debate. The prevalence of psychiatric disorders is high in IBS patients. Positive response to antidepressant therapy and presence of family history of depression in IBS patients have led speculations whether this syndrome might be regarded as an affective spectrum disorder. In this study we tried to examine the possible association of IBS with affective spectrum disorders. METHOD: Forty IBS patients from gastroenterology outpatient clinics of a university hospital and state hospital, 32 controls with inflammatory bowel disease and 34 healthy hospital workers were included in the study. Psychiatric interviews were done using SCID-NP (Structured Clinical Interview for DSM-Non-patients) and psychological factors were assessed by the SCL-90-R (Symptom Checklist-90-Revised), the Beck Depression Inventory, the Beck Anxiety Scale and the Hamilton Rating Scale for Depression. Family histories were obtained by FH-RDC (Family History Research Diagnostic Criteria). All groups were matched for sociodemographic variables. RESULTS: The prevalence of psychiatric disorders and mood disorders was higher in the IBS group than the control groups. Also IBS group rated higher on anxiety and depression scales than the other groups, where the differences were statistically significant. Presence of positive family history for mood disorders was higher in the IBS group. CONCLUSION: These results support the hypothesis that IBS might be linked to affective spectrum disorder. Psychiatric assessment and therapy might be useful in the course of irritable bowel syndrome.

Clinical features and therapy of medication overuse headache.

Inappropriate use of headache medication (>15 times/month) for the treatment of headache episodes may contribute to the development of chronic headache which is refractory to most treatments. Physicians experienced in the treatment of migraine and other headaches are well aware that the daily intake of antipyretic or antiinflammatory analgesics, opioids, ergot alkaloids and "triptans" may result in chronic daily headache. Conversely, if a patient complains of chronic headache and takes pain medication every day, this headache is most likely to be caused and sustained by the medication and will vanish or improve with abstinence. Treatment includes drug withdrawal followed by structured acute therapy and initiation of migraine prophylactic treatment.

Superior safety of reboxetine over amitryptiline in the elderly.

Under antidepressive treatment with amitryptiline (100 mg/d) a 71-year old woman developed delirious symptoms, hyponatremia and a grand mal seizure followed by cardiovascular arrest. A few month later she ingested 48 mg reboxetine with suicidal intent. Overdosing of reboxetine, a selective noradrenaline re-uptake inhibitor, proceeded without complications.

Alexithymia in patients with antisocial personality disorder in a military hospital setting.

We investigated the prevalence of alexithymic features and other psychometric correlates in patients diagnosed with antisocial personality disorder in a military hospital setting. Forty soldiers diagnosed with antisocial personality disorder in a general military hospital and 50 normal soldiers with no known medical or psychiatric disorder were assessed by sociodemographic data form, the Toronto Alexithymia Scale (TAS)-26 items, the Beck Depression Scale, the Beck Hopelessness Scale, the Brief Symptom Inventory and the State-Trait Anxiety Inventory. Antisocial patients showed significantly higher rates of unemployment, lower educational and socioeconomic status, higher rates of self mutilation, previous suicide attempts, substance abuse, history of incarceration and broken family bonds. The patient group also displayed significantly higher scores on alexithymia, depression, hopelessness and general psychological distress measures. Alexithymia was not associated with other psychological measures but was associated with socioeconomic and educational status. The failure in the socialization process of these patients may pave the way for an inability to identify and communicate their feelings. To draw a more definitive conclusion on this issue, a study which recruits ASPD patients from the community and compares them with a sociodemographically matched patient control group is necessary.

Dietary selenium and vitamin E intakes alter beta-adrenergic response of L-type Ca-current and beta-adrenoceptor-adenylate cyclase coupling in rat heart.

Previously we have shown that both insufficient (combined with vitamin E deficiency) and excess intake of selenium (Se) impairs isoproterenol (ISO)-induced contractions of rat papillary muscle. In the present study, we used patch-clamp and biochemical techniques to investigate mechanisms of this effect in rats fed a Se- and vitamin E-deficient, a Se-excess or a normal diet. Whole-cell configuration of patch-clamp technique was used to investigate L-type Ca(2+) currents (I(Ca,L)) and their regulation by beta-adrenergic receptor stimulation in enzymatically isolated single rat ventricular myocytes. Alteration of Se and vitamin E intake did not affect peak I(Ca,L), but the threshold potential of activation was significantly different among groups. Maximal I(Ca,L) responses to ISO were depressed in both experimental groups, but the EC(50) values were not affected. In the Se-deficient group, basal, ISO- or forskolin-induced adenylate cyclase (AC) activity, measured in cardiac membrane preparations, was reduced when compared to the control, whereas 5' guanylyimidodphosphate (GppNHp) stimulated activity was unaffected. Decreased beta-adrenoceptor density and reduced GppNHp-induced affinity shift in ISO binding were also observed in the deficient group. No such differences were present in the excess group. These results suggest that combined Se and vitamin E deficiency interferes with beta-adrenoceptor-AC coupling, whereas excess intake of Se does not affect it. Thus, in the deficient group, the impairment of I(Ca) responses to ISO may be a result of a defect in beta-adrenoceptor-AC pathway. Impairment of I(Ca) response in the excess group, however, appears to have a different underlying mechanism.

Anger attacks in depressed Turkish outpatients.

Anger attacks have been described as sudden spells of anger accompanied by symptoms of autonomic activation and have been experienced by patients as uncharacteristic of them and inappropriate to the situations in which they had occurred. The aim of this study was to assess the prevalence of anger attacks in a non-Western depressed population. We also wanted to see whether depression in patients with anger attacks was qualitatively different from depression without anger attacks. The Anger Attacks Questionnaire, designed by Fava et al. to assess these attacks, was administered to 88 medication-free consecutive outpatients diagnosed as major depression according to DSM-IV criteria by two psychiatrists. The patients also were assessed by the Beck Depression Inventory, the Beck Anxiety Inventory, the Beck Hopelessness Scale, and the Spielberger's State-Trait Anger Expression Inventory. Forty-three (49%) of these patients had reported having anger attacks. The patients with anger attacks were significantly more depressed and anxious than patients without anger attacks. Anger-out and trait anger measures were significantly higher in depressed patients with anger attacks than patients without anger attacks. Patients with anger attacks also scored higher in hopelessness measure and there was a trend toward statistical significance. Our results are in line with previous literature which show, that anger attacks are prevalent in depressed patients. We also conclude that patients with anger attacks constitute a more depressed population than those without anger attacks. Severity of depression emerges as the strongest predictor of the presence of anger attacks in our study.