Repeated administration of imipramine attenuates glutamatergic transmission in rat frontal cortex

The effects of repeated administration of a tricyclic antidepressant, imipramine, lasting 14 days (10 mg/kg p.o., twice daily), were studied ex vivo in rat frontal cortex slices prepared 48 h after last dose of the drug. In slices prepared from imipramine-treated animals the mean frequency, and to a lesser degree the mean amplitude, of spontaneous excitatory postsynaptic currents recorded from layer II/III pyramidal neurons, were decreased. These effects were accompanied by a reduction of the initial slope ratio of pharmacologically isolated N-methyl-D-aspartate to AMPA/kainate receptor-mediated stimulation-evoked excitatory postsynaptic currents. Imipramine treatment also resulted in a decrease of extracellular field potentials evoked in layer II/III by stimulation of underlying sites in layer V. These results indicate that chronic treatment with imipramine results in an attenuation of the release of glutamate and an alteration in the postsynaptic reactivity of ionotropic glutamate receptors in rat cerebral cortex.

Effect of stress-induced reversible ischemia on serum concentrations of ischemia-modified albumin, natriuretic peptides and placental growth factor

OBJECTIVE

There is controversy whether new biomarkers are able to identify myocardial ischemia in the absence of myonecrosis.

METHOD

We measured NT-pro BNP, NT-pro ANP, ischemia-modified albumin (IMA) and placental growth factor (PlGF) in patients undergoing nuclear stress testing for suspected ischemic heart disease. A thallium scan was used for detection of reversible myocardial ischemia and cardiac troponin T (cTnT) for exclusion of stress-induced myonecrosis. Of 195 patients, 24 with reversible and 62 with no perfusion defect were included in the analysis. Plasma levels were measured before, 18 min and 4 h after stress testing.

RESULTS

Of the 86 patients, 52 received an exercise stress and 34 dipyridamol. New myonecrosis indicated by cTnT could be excluded in all patients. Plasma levels of NT-pro BNP and NT-pro ANP before testing were significantly higher in patients who later developed reversible perfusion defects (NT-pro BNP 139.00 (58.25/367.01) pg/mL vs 327.45 (120.50/972.85) pg/mL, p<0.05; NT-pro ANP 732.5 (470.0/1220.0) pg/mL vs 1470.0 (694.0/1910.0) pg/mL, p<0.05). Plasma levels of NT-pro BNP, NT-pro ANP and PIGF did not change significantly after stress testing, IMA levels rose significantly after 4 h in patients with and without reversible perfusion defects.

CONCLUSION

The elevation of NTpro BNP and NT-pro ANP at baseline may represent the cumulative effect of repeated bouts of myocardial ischemia. A single brief episode of provoked ischemia does not cause a significant increase of the measured biomarkers beside from IMA after exercise stress test potentially indicating skeletal muscle ischemia.

Effect of primer selection on estimates of GB virus C (GBV-C) prevalence and response to antiretroviral therapy for optimal testing for GBV-C viremia

GB virus C (GBV-C; also called hepatitis G virus) is a common cause of infection associated with prolonged survival among HIV-infected individuals. The prevalences of GBV-C viremia vary widely in different studies, and there has been poor agreement among different laboratories performing GBV-C RNA detection in quality control studies. To determine the optimal method of measuring GBV-C RNA in clinical samples, samples obtained from 939 HIV-infected subjects were studied using reverse transcription (RT)-PCR methods amplifying four separate regions of the GBV-C genome. Primers amplifying the E2 coding region were 100% specific; however, their sensitivity was only 76.6%. In contrast, primers amplifying three additional conserved regions of the GBV-C genome (the 5' nontranslated region and the nonstructural protein-coding regions 3 and 5A) were more sensitive but produced higher rates of false-positive results. Using low-specificity primer sets influenced the significance of association between GBV-C viremia and response to antiretroviral therapy. Using a quantitative GBV-C RNA method, the GBV-C RNA concentration did not correlate with baseline or set point HIV RNA levels; however, a correlation between negative, low, and high GBV-C RNA levels and increasing reduction in HIV RNA following antiretroviral therapy was observed. Subjects with both GBV-C E2 antibody and viremia had significantly lower GBV-C RNA levels than did viremic subjects without E2 antibody. These studies demonstrate that accurate detection of GBV-C RNA by nested RT-PCR requires the use of primers representing multiple genome regions. Analyses based on testing with single primers do not lead to reliable conclusions about the association between GBV-C infection and clinical outcomes.

Imipramine and citalopram reverse corticosterone-induced alterations in the effects of the activation of 5-HT(1A) and 5-HT(2) receptors in rat frontal cortex

Using extracellular recording we studied changes in the reactivity of rat frontal cortical slices to the 5-HT(1A), 5-HT(2) and 5-HT(4) receptor agonists, (+/-)-2-dipropyloamino-8-hydroxy-1,2,3,4-tetrahydronaphtalene hydrobromide (8-OH-DPAT), (+/-)-2,5-dimethoxy-4-iodoamphetamine hydrochloride (DOI) and zacopride, respectively, induced by an earlier treatment of animals with corticosterone lasting 1 or 3 weeks. Spontaneous bursting activity was recorded in ex vivo slices incubated in a medium devoid of Mg(2+) ions and containing picrotoxin (30 microM). Repetitive, but not single, corticosterone administration resulted in an attenuation of the effect of the activation of 5-HT(1A) receptors and in an enhancement of the effect related to 5-HT(2) receptors. The effect of 5-HT(4) receptor activation remained unchanged. In separate two sets of experiments rats were treated with corticosterone for 3 weeks and additionally with imipramine or citalopram, beginning on the eighth day of corticosterone administration. In the corticosterone plus imipramine as well as corticosterone plus citalopram groups the effects of 8-OH-DPAT and DOI were not different from control indicating that corticosterone-induced functional modifications in the reactivity of 5-HT(1A) and 5-HT(2) receptors were reversed by antidepressant treatments.

Simultaneous functional magnetic resonance imaging in the rat spinal cord and brain

Functional magnetic resonance imaging (fMRI) method was developed to investigate the pattern and temporal relationship in neuronal pathways of brain and spinal cord. Signal intensity changes correlating with stimulation patterns were observed simultaneously in the rat spinal cord and brain using fMRI at 9.4 T. Electrical stimulation of the forepaw was used to elicit activity. A quadrature volume RF coil covering both brain and the cervical spinal cord was used. Sets of fast spin echo (FSE) images were acquire simultaneously for both brain and spinal cord fMRI. Experiments were repeated in single animal and across animals. Activities within the dorsal horn of the spinal cord and within the somatosensory cortex were observed consistently within each animal as well as across animals.

N-Terminal-proBNP (NT-proBNP) as an indicator of cardiac dysfunction

BACKGROUND

Natriuretic peptides represent a novel diagnostic tool in the assessment of cardiac dysfunction.

METHODS

A total of 473 consecutive referred patients presenting to 18 cardiologists for the assessment of their cardiac state were recruited for the study. Patients received a medical history, a physical examination an electrocardiogram and an echocardiogram where left ventricular ejection fraction was recorded.

RESULTS

NT-proBNP was found to correlate with left ventricular ejection fraction (LVEF), level of symptoms (NYHA classification), history of angina pectoris (AP) and myocardial infarction (AMI). Atrial fibrillation (AF) and thyroid dysfunction as well as renal impairment were shown to influence NT-proBNP levels.

CONCLUSION

The study supports the hypothesis that NT-proBNP determination contributes to the assessment of patients presenting to cardiologists.

Plasma N-terminal pro-brain natriuretic peptide as a major risk marker for cardiovascular disease in patients with type 2 diabetes and microalbuminuria

AIMS/HYPOTHESIS

We examined whether plasma N-terminal probrain natriuretic peptide (NT-proBNP) predicts cardiovascular outcome in patients with type 2 diabetes.

METHODS

A total of 160 microalbuminuric type 2 diabetic patients (mean age 55.1 years [SD 7.2], 119 men) were enrolled in the Steno-2 Study examining the effect of multifactorial treatment, and were divided into two groups according to baseline levels of plasma NT-proBNP below or above the median for the cohort, which was followed for an average of 7.8 years. Cardiovascular outcome was a composite of cardiovascular mortality, myocardial infarction, stroke, revascularisation procedures in the heart or legs, and amputations.

RESULTS

In the whole group, plasma NT-proBNP being above the median was associated with an increased risk of cardiovascular disease during follow-up, with an unadjusted hazard ratio of 4.4 (95% CI 2.3-8.4; p<0.0001). A decrease in plasma NT-proBNP of 10 pg/ml during the first 2 years of intervention was associated with a 1% relative reduction in the primary endpoint (p<0.001). Despite polypharmacological treatment targeting cardiovascular disease, the mean plasma NT-proBNP level increased during follow-up.

CONCLUSIONS/INTERPRETATION

We conclude that high plasma NT-proBNP is a major risk marker for cardiovascular disease in patients with type 2 diabetes and microalbuminuria.

The influence of repeated administration of clozapine and haloperidol on the effects of the activation of 5-HT(1A), 5-HT(2) and 5-HT(4) receptors in rat frontal cortex

The effects of a repeated treatment with antipsychotic drugs, clozapine and haloperidol, on the modulation of network activity ex vivo by 5-HT receptors were examined in rat frontal cortical slices using extracellular recording. Rats were treated for 21 days with clozapine (30 mg/kg p.o.), or haloperidol (1 mg/kg p.o.). Spontaneous bursting activity was induced in slices prepared 3 days after the last drug administration by perfusion with a medium devoid of Mg(2+) ions and with added picrotoxin (30 mM). The application of 2-3 microM 8-OH-DPAT, acting through 5-HT(1A) receptors, resulted in a reversible decrease of bursting frequency. In the presence of 1 microM DOI, the 5-HT(2) agonist, or 5 microM zacopride, the 5-HT(4) agonist, bursting frequency increased. Chronic clozapine treatment resulted in an attenuation of the effect of the activation of 5-HT(2) receptors, while the effects related to 5-HT(1A) and 5-HT(4) receptor activation were unchanged. Treatment with haloperiol did not influence the reactivity to the activation of any of the three 5-HT receptor subtypes. These data are consistent with earlier findings demonstrating a selective downregulation of 5-HT(2A) receptors by clozapine and indicate that chronic clozapine selectively attenuates the 5-HT-mediated excitation in neuronal circuitry of the frontal cortex while leaving the 5-HT-mediated inhibition intact.

Repeated administration of antidepressants decreases field potentials in rat frontal cortex

The effects of repeated administration of a tricyclic antidepressant, imipramine, and a selective serotonin reuptake blocker, citalopram, for 14 days (10 mg/kg p.o., twice daily), were studied ex vivo in rat frontal cortex slices prepared 48 h after last dose of the drug. Treatment with both antidepressants resulted in a decrease in the amplitude of field potentials evoked in layer II/III by stimulation of underlying sites in layer V. The amplitude ratio of pharmacologically isolated N-methyl-D-aspartic acid (NMDA) to alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainate receptor-mediated components of the field potential was reduced. These results indicate that chronic treatment with imipramine or citalopram results in an attenuation of glutamatergic synaptic transmission in the cerebral cortex.

Safety and feasibility of CHOP/rituximab induction treatment followed by high-dose chemo/radiotherapy and autologous PBSC-transplantation in patients with previously untreated mantle cell or indolent B-cell-non-Hodgkin's lymphoma

Patients with no prior chemotherapy and with advanced and progressive follicular lymphoma (FCL) or mantle cell lymphoma (MCL) were enrolled into a treatment protocol combining CHOP/rituximab-CHOP therapy with subsequent consolidation high-dose therapy (HDT) to evaluate the safety and feasibility of this treatment. Overall, 15 patients were enrolled and 13 patients completed the entire treatment protocol without major toxicities or increased infectious complications. One patient withdrew consent after achieving complete remission (CR) prior to HDT. One patient was taken off study with signs of disease progression after induction treatment. All patients showed stable engraftment after HDT. Response rates appear to be favorable, indicating an additional effect of rituximab and HDT. Overall, 12 of 13 patients achieved CR/CRu and one patient partial remission. Follow-up of immune reconstitution displayed transient severe combined immunodeficiency with slow normalization of the cellular and humoral compartments without a significant increase of infectious complications. Taken together, high-dose chemotherapy can be safely given following treatment with CHOP+rituximab. Efficacy in this small cohort of patients was encouraging with sustained remissions in both FCL and MCL patients. Upfront HDT should be considered as a therapeutic option especially in young and/or high-risk patients.

Rituximab as in vivo purging agent in autologous stem cell transplantation for relapsed B-NHL

In vivo purging may avoid relapse after high dose therapy (HDT) for relapsed lymphoma. Therefore, we have evaluated feasibility and efficacy of Rituximab as in vivo purging agent included into a sequential salvage protocol for CD20+ B-NHL in chemosensitive relapse or induction failure. Thirty seven patients were treated within this protocol and in 36/37 a stem cell product could be acquired with rare NHL contamination. Overall, due to the intensity of treatment there has been a substantial morbidity, including high rates of viral reactivation. However, only one patient died during treatment due to sepsis. Response rates were favourable with an overall response rate of 97% (with 30/35CR). With a maximum follow up of 3.5 years, 15 patients relapsed. Overall, the treatment protocol has proven feasible with high purging efficiency and encouraging remission rates in this unfavourable patient group.

Anisomycin treatment paradigm affects duration of long-term potentiation in slices of the amygdala

Anisomycin has been widely used as an inhibitor of protein synthesis in studies on learning and memory as well as synaptic plasticity. However, its mode of action is complicated. Besides the inhibition of translation, this drug displays other effects, most prominently on mitogen-activated protein kinases. In this report we analyze the effects of anisomycin on the late phase of long-term potentiation (LTP) in amygdala slices. The late phase of LTP was evoked by high-frequency repeated-train stimulation delivered to the external capsule and recorded in the lateral amygdaloid nucleus. In the no-drug condition, stimulation resulted in LTP lasting over 3 h without any sign of decay. Application of the drug 15 min before high-frequency stimulation (HFS) caused LTP decay to baseline within 1 h after induction. However, delivering the drug just after the first train of HFS resulted in LTP that returned to baseline level within 3 h since the onset of stimulation. These results show that the duration of the LTP in the amygdala depends on the anisomycin treatment paradigm and thus special caution should be exercised when interpreting the data obtained with this drug.

Rituximab in vivo purging is safe and effective in combination with CD34-positive selected autologous stem cell transplantation for salvage therapy in B-NHL

The purpose of this study was to evaluate feasibility and efficacy of Rituximab included into a sequential salvage protocol for CD20(+) B-NHL in relapse or induction failure. Twenty-seven patients with CD20(+) B-NHL in relapse or induction failure received Rituximab combined with DexaBEAM (R-DexaBEAM) for stem cell mobilization. Additional ex vivo selection of CD34-positive cells was performed using the CliniMacs device. Two doses of Rituximab were included in the high-dose therapy regimen (HDT). R-DexaBEAM was well tolerated and 26 of 27 patients mobilized sufficient numbers of CD34(+) blood stem cells. Application of R-DexaBEAM resulted in significant depletion of peripheral B cells. No treatment-related deaths occurred after HDT and all patients showed stable engraftment of hematopoesis. Combined immunodeficiency was observed post HDT and eight patients developed CMV antigenemia. Remission rate post HDT was 96% (CR, 24/26; PR, 1/26). Overall and progression-free survival (PFS) at 16 months post HDT (range 6-27) is 95% and 77%, respectively. With regard to histology, PFS was 71% in aggressive lymphoma (n = 11), 74% in indolent FCL (n = 10) and 100% in MCL (n = 5). The treatment protocol has proven feasible, with high purging efficiency and encouraging remission rates.

Repeated imipramine administration enhances the effects of NMDA receptor ligands on synchronous activity in rat frontal cortex in vitro

This study assessed the effects of repeated administration (14 days) of imipramine on the function of NMDA receptors by measuring the frequency of spontaneous epileptiform discharges which develop in rat frontal cortical slices incubated in Mg2+-free conditions. Imipramine significantly enhanced both the excitatory effect of NMDA and the inhibitory effect of the competitive NMDA receptor antagonist CGP 37849 on the frequency of discharges. These results are consistent with studies indicating that chronic administration of antidepressant drugs induces adaptive changes in NMDA receptor/ channel complex in the cerebral cortex.

A proposed client self-care commitment model

PURPOSE

Expansion of the dental hygiene body of knowledge offers options for the profession; evolving conceptual models allow practitioners to choose an approach to client care that is scientifically sound yet matches individual philosophies. Health paradigms for different approaches to client care have been developed and used in medical anthropology, psychology, and dental hygiene. Adapted from the biomedical model, the explanatory model, the empowerment model, and the human needs conceptual model, a new model for client commitment is proposed. The client self-care commitment model is composed of five domains: initiation, assessment, negotiation, commitment, and evaluation. This model proposes that the relationships among these domains, and the interaction between the client and the dental hygienist can empower clients to make decisions that will enhance their own health through commitment and compliance. This paper reviews the scientific literature from medical anthropology, psychology, and dental hygiene that focus on client care, and suggests possible applications of the model to the dental hygiene process of care, dental hygiene education, and qualitative research.

[Field potential recording for investigation of synaptic plasticity in vitro]

The in vitro brain slice preparations have been widely employed for investigation of the cellular mechanisms underlying long-term potentiation and long-term depression of synaptic transmission in the rodent hippocampus. The determination of spatiotemporal patterns of activation by means of current source-density analysis of evoked field potentials allows for the use of field potential recording in the research on neocortical synaptic plasticity, in particular in horizontal connections of the motor cortex.

Tetraethylammonium-induced long-term potentiation in layer V horizontal connections of rat motor cortex

The possibility for the induction of long-lasting synaptic plasticity by the potassium channel blocker tetraethylammonium (TEA) was investigated in adult rat motor cortex in vitro. Brief application of TEA (25 mM) resulted in a long-term potentiation (LTP(K)) of field potentials evoked in layer V intralaminar connections by 59+/-17%. This effect could be prevented by preincubation with nifedipine, a voltage-dependent calcium channel blocker (20 microM), but not by N-methyl-D-aspartate (NMDA) receptor antagonist 2-amino-5-phosphonovalerate (APV, 100 microM). LTP(K) induction resulted in a smaller relative potentiation of a response to the second pulse of a pair (60 ms interpulse interval). These results indicate a potential of layer V horizontal connections for a NMDA receptor-independent form of persistent synaptic enhancement.

Serological pattern "anti-HBc alone": report on a workshop

In areas with low hepatitis B virus (HBV) endemicity such as most parts of Europe and the United States "anti-HBc alone" is found in 10-20% of all individuals with HBV markers, i.e., 1-4% of the population. In about 10% of these individuals HBV DNA is detected by PCR, the proportions varying greatly depending on the population studied, being highest in individuals coinfected with hepatitis C virus (HCV) (above 35%) and HIV (above 85%). A small proportion of individuals with "anti-HBc alone" are in the window phase of an HBV infection or in a stage of late HBV immunity. For the large proportion of these individuals this is not the case and they are thought to have an unresolved HBV-infection or a chronic infection in a late or "low grade" productive state. Currently, limited studies have been performed concerning the clinical aspects of individuals with "anti-HBc alone" and suspected chronic HBV infection. The majority of these individuals seem to be healthy. Some chronic carriers with "anti-HBc alone," however, do present signs of chronic hepatitis. Individuals with "anti-HBc alone" are potentially infectious. This is exemplified by a few case reports of HBV transmission to sexual contacts, perinatal transmission between mother and newborns and in blood recipients. Recommendations are given in relation to both the diagnostic and therapeutic procedures in the individuals with "anti-HBc alone" and in the blood banking and transplantation services.

Induction of psychogenic nonepileptic seizures without placebo

The diagnosis of psychogenic nonepileptic seizures (PNES) can only be made with EEG-video monitoring. The authors describe a provocative technique without placebo. Patients with a clinical suspicion for PNES underwent an activation procedure using suggestion, hyperventilation, and photic stimulation. Of 19 inductions performed, 16 (84%) were successful in inducing the habitual episode. The authors' technique had a sensitivity comparable to those using placebo (e.g., saline injection), but does not have disadvantages.