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2.
Klin Monbl Augenheilkd ; 234(9): 1161-1168, 2017 Sep.
Article in German | MEDLINE | ID: mdl-28514814

ABSTRACT

Purpose Central serous chorioretinopathy (CSC) is a commonly acquired maculopathy characterized by the accumulation of subretinal fluid at the posterior pole. This study aims to analyze optical coherence tomography angiography (OCTA) findings in patients with acute and chronic CSC and to compare them to conventional imaging methods. Methods A series of 43 consecutive eyes of 29 patients diagnosed with CSC and 18 eyes of 9 healthy control subjects were included in this retrospective study. The OCTA images were assessed and compared to conventional fluorescence (FAG) and indocyanine green angiography (ICG). Results All CSC patients demonstrated abnormal areas of focal hypo- and hyperperfusion in the choriocapillaris. These were particularly evident in patients with chronic atrophic CSC. FAG and ICG imaging revealed leakage points in 10 of 43 eyes and choroidal neovascularization (CNV) in 3 of 43 eyes. OCTA imaging confirmed leakage points in 4 out of 10 cases and choroidal neovascularization in 2 out of 3 cases. In one case, OCTA demonstrated a CNV which was not detectable by FAG/ICG. Conclusion OCTA reveals areas of focal hypo- and hyperperfusion in the choriocapillaris in patients with CSC. Due to the inability to detect plasma flow, OCTA is not suitable to detect leakage points in CSC with confidence. However, OCTA reliably detects CNV in CSC even in the absence of exudative activity and may, therefore, represent an important supplement in the diagnosis of CSC.


Subject(s)
Angiography/methods , Central Serous Chorioretinopathy/diagnostic imaging , Tomography, Optical Coherence/methods , Adult , Female , Fluorescein Angiography , Humans , Image Interpretation, Computer-Assisted/methods , Male , Middle Aged , Reference Values , Sensitivity and Specificity , Statistics as Topic , Subretinal Fluid/diagnostic imaging
3.
Blood Cancer J ; 6: e404, 2016 Mar 11.
Article in English | MEDLINE | ID: mdl-26967821

ABSTRACT

Efficacy of lenalidomide was investigated in 103 patients with relapsed/refractory chronic lymphocytic leukemia (CLL) treated on the prospective, multicenter randomized phase-II CLL-009 trial. Interphase cytogenetic and mutational analyses identified TP53 mutations, unmutated IGHV, or del(17p) in 36/96 (37.5%), 68/88 (77.3%) or 22/92 (23.9%) patients. The overall response rate (ORR) was 40.4% (42/104). ORRs were similar irrespective of TP53 mutation (36.1% (13/36) vs 43.3% (26/60) for patients with vs without mutation) or IGHV mutation status (45.0% (9/20) vs 39.1% (27/68)); however, patients with del(17p) had lower ORRs than those without del(17p) (21.7% (5/22) vs 47.1% (33/70); P=0.049). No significant differences in progression-free survival and overall survival (OS) were observed when comparing subgroups defined by the presence or absence of high-risk genetic characteristics. In multivariate analyses, only multiple prior therapies (⩾3 lines) significantly impacted outcomes (median OS: 21.2 months vs not reached; P=0.019). This analysis indicates that lenalidomide is active in patients with relapsed/refractory CLL with unfavorable genetic profiles, including TP53 inactivation or unmutated IGHV. (ClinicalTrials.gov identifier: NCT00963105).


Subject(s)
Antineoplastic Agents/therapeutic use , Drug Resistance, Neoplasm , Immunologic Factors/therapeutic use , Leukemia, Lymphocytic, Chronic, B-Cell/diagnosis , Leukemia, Lymphocytic, Chronic, B-Cell/drug therapy , Thalidomide/analogs & derivatives , Aged , Aged, 80 and over , Female , Follow-Up Studies , Humans , Immunoglobulin Heavy Chains/genetics , Lenalidomide , Leukemia, Lymphocytic, Chronic, B-Cell/genetics , Male , Middle Aged , Mutation , Prognosis , Recurrence , Retreatment , Survival Analysis , Thalidomide/therapeutic use , Treatment Outcome , Tumor Suppressor Protein p53/genetics
4.
Gesundheitswesen ; 77 Suppl 1: S112-3, 2015 Sep.
Article in German | MEDLINE | ID: mdl-24671887

ABSTRACT

The school system is an established setting for behavioural and environmental tobacco prevention activities. Most research on the effectiveness of tobacco prevention has been conducted with regard to behavioural approaches, knowledge about school smoking policy is lacking. This research project aimed at developing a psychometrically sound instrument to assess school smoking policy. The checklist presented here contains five scales with a total of 15 items. Its reliability was tested with 42 Bavarian schools and 607 schools from Hesse. The checklist allows to measure school smoking policy in a reliable and action-oriented manner.


Subject(s)
Checklist/statistics & numerical data , Health Policy , Health Promotion/statistics & numerical data , Schools/statistics & numerical data , Smoking Prevention , Smoking/epidemiology , Adolescent , Female , Germany/epidemiology , Humans , Male , Outcome Assessment, Health Care/methods , Outcome Assessment, Health Care/statistics & numerical data , Program Evaluation/methods , School Health Services
5.
Gesundheitswesen ; 77 Suppl 1: S64-5, 2015 Sep.
Article in German | MEDLINE | ID: mdl-23572470

ABSTRACT

The aim of this study was to develop an effective selective preventive programme for the risk group of children of depressed mothers. A universal parent and child training concept was adapted to the target group and to mother-child rehabilitation clinic conditions. A quasi-experimental design was implemented with 13 clinics. Evaluation of the results reveals that EFFEKT-E is an accepted, feasible selective programme which has the potential to enhance maternal competence and prevent children's emotional disruption.


Subject(s)
Depression/prevention & control , Depression/psychology , Health Promotion/organization & administration , Maternal Health Services/organization & administration , Maternal Health , Mother-Child Relations/psychology , Adolescent , Adult , Child , Child of Impaired Parents/psychology , Child, Preschool , Depression/diagnosis , Female , Germany , Humans , Male , Preventive Health Services/organization & administration , Program Evaluation , Treatment Outcome , Young Adult
6.
Gesundheitswesen ; 77 Suppl 1: S25-6, 2015 Sep.
Article in German | MEDLINE | ID: mdl-23757100

ABSTRACT

Obese children mostly become obese adults. The aim of this study was to test whether the kindergarten setting is a successful access point for universal and selective prevention measures for preschool children and their parents. In a randomised controlled trial, the universal effects on risk and protective factors were observed. But recruitment for the selective programme did not work out which may be due to a biased risk perception of childhood overweight development and high prevention self-efficacy. Alternative strategies are explored.


Subject(s)
Family/psychology , Health Promotion/methods , Patient Selection , Pediatric Obesity/prevention & control , Pediatric Obesity/psychology , Primary Prevention/methods , Attitude to Health , Child Welfare/psychology , Child, Preschool , Female , Germany , Humans , Male , Parents/psychology , Patient Acceptance of Health Care/psychology , Research Subjects/psychology , Schools , Treatment Outcome , Vulnerable Populations/psychology
7.
Nat Commun ; 5: 4504, 2014 Jul 25.
Article in English | MEDLINE | ID: mdl-25060143

ABSTRACT

The quest for realization of non-Abelian phases of matter, driven by their possible use in fault-tolerant topological quantum computing, has been spearheaded by recent developments in p-wave superconductors. The chiral p(x)+ip(y)-wave superconductor in two-dimensions exhibiting Majorana modes provides the simplest phase supporting non-Abelian quasiparticles and can be seen as the blueprint of fractional topological order. Alternatively, Kitaev's Majorana wire has emerged as an ideal toy model to understand Majorana modes. Here we present a way to make the transition from Kitaev's Majorana wires to two-dimensional p-wave superconductors in a system with cold atomic gases in an optical lattice. The main idea is based on an approach to generate p-wave interactions by coupling orbital degrees of freedom with strong s-wave interactions. We demonstrate how this design can induce Majorana modes at edge dislocations in the optical lattice, and we provide an experimentally feasible protocol for the observation of the non-Abelian statistics.

9.
Exp Eye Res ; 115: 73-8, 2013 Oct.
Article in English | MEDLINE | ID: mdl-23800510

ABSTRACT

Cysteine cathepsins are a family of proteases involved in intracellular protein turnover and extracellular matrix degradation. Cathepsin B (Ctsb) and cathepsin Z (Ctsz) promote tumorigenesis and Ctsb is a known modulator of tumor angiogenesis. We therefore investigated the angiomodulatory function of these cathepsins in vitro as well as in a mouse model of laser-induced choroidal neovascularization (laser-CNV). Ctsb(-/-), Ctsz(-/-), Ctsb/Ctsz double-knockout (Ctsb/z DKO), and wild type (WT) mice underwent argon laser treatment to induce choroidal neovascularization (CNV). The neovascularized area was quantified individually for each lesion at 14 days after laser coagulation. In vitro the effects of cathepsin inhibitors on angiogenesis were analysed by endothelial cell (EC) spheroid sprouting and EC invadosome assays. Retinas from cathepsin KO mice did not show gross morphological abnormalities. In the laser CNV model, however, Ctsb/z DKO mice displayed a significantly reduced neovascularized area compared to WT (0.027 mm(2) vs. 0.052 mm(2); p = 0.012), while single knockouts did not differ significantly from WT. In line, VEGF-induced EC spheroid sprouting and invadosome formation were not significantly altered by a specific cathepsin B inhibitor alone, but significantly suppressed when more than one cathepsin was inhibited. Our results demonstrate that laser-CNV formation is significantly reduced in Ctsb/z DKO mice. In line, EC sprouting and invadosome formation are blunted when more than one cathepsin is inhibited in vitro. These results reveal an angiomodulatory potential of cathepsins with partial functional redundancies between different cathepsin family members.


Subject(s)
Cathepsin B/physiology , Cathepsin Z/physiology , Choroid/blood supply , Choroidal Neovascularization/enzymology , Disease Models, Animal , Laser Coagulation , Animals , Cathepsin B/antagonists & inhibitors , Cathepsin Z/antagonists & inhibitors , Choroidal Neovascularization/pathology , Enzyme Inhibitors/pharmacology , Extracellular Matrix/metabolism , Human Umbilical Vein Endothelial Cells/drug effects , Lasers, Gas , Matrix Metalloproteinase Inhibitors/pharmacology , Mice , Mice, Inbred C57BL , Mice, Knockout , Spheroids, Cellular , Vascular Endothelial Growth Factor A/pharmacology
10.
Neuroscience ; 238: 29-38, 2013 May 15.
Article in English | MEDLINE | ID: mdl-23415792

ABSTRACT

While intense or highly arousing stressors have long been known to suppress pain, relatively mild or chronic stress can enhance pain. The mechanisms underlying stress-induced hyperalgesia (SIH) are only now being defined. The physiological and neuroendocrine effects of mild stress are mediated by the dorsomedial hypothalamus (DMH), which has documented connections with the rostral ventromedial medulla (RVM), a brainstem region capable of facilitating nociception. We hypothesized that stress engages both the DMH and the RVM to produce hyperalgesia. Direct pharmacological activation of the DMH increased sensitivity to mechanical stimulation in awake animals, confirming that the DMH can mediate behavioral hyperalgesia. A behavioral model of mild stress also produced mechanical hyperalgesia, which was blocked by inactivation of either the DMH or the RVM. The neuropeptide cholecystokinin (CCK) acts in the RVM to enhance nociception and is abundant in the DMH. Using a retrograde tracer and immunohistochemical labeling, we determined that CCK-expressing neurons in the DMH are the only significant supraspinal source of CCK in the RVM. However, not all neurons projecting from the DMH to the RVM contained CCK, and microinjection of the CCK2 receptor antagonist YM022 in the RVM did not interfere with SIH, suggesting that transmitters in addition to CCK play a significant role in this connection during acute stress. While the RVM has a well-established role in facilitation of nociception, the DMH, with its well-documented role in stress, may also be engaged in a number of chronic or abnormal pain states. Taken as a whole, these findings establish an anatomical and functional connection between the DMH and RVM by which stress can facilitate pain.


Subject(s)
Cholecystokinin/metabolism , Dorsomedial Hypothalamic Nucleus/physiopathology , Hyperalgesia/physiopathology , Medulla Oblongata/physiopathology , Stress, Psychological/physiopathology , Animals , Benzodiazepines/pharmacology , Dorsomedial Hypothalamic Nucleus/drug effects , Dorsomedial Hypothalamic Nucleus/metabolism , Hormone Antagonists/pharmacology , Male , Medulla Oblongata/drug effects , Medulla Oblongata/metabolism , Pain Measurement , Rats , Rats, Sprague-Dawley , Receptor, Cholecystokinin B/antagonists & inhibitors , Stress, Psychological/metabolism
12.
Lancet ; 376(9747): 1164-74, 2010 Oct 02.
Article in English | MEDLINE | ID: mdl-20888994

ABSTRACT

BACKGROUND: On the basis of promising results that were reported in several phase 2 trials, we investigated whether the addition of the monoclonal antibody rituximab to first-line chemotherapy with fludarabine and cyclophosphamide would improve the outcome of patients with chronic lymphocytic leukaemia. METHODS: Treatment-naive, physically fit patients (aged 30-81 years) with CD20-positive chronic lymphocytic leukaemia were randomly assigned in a one-to-one ratio to receive six courses of intravenous fludarabine (25 mg/m(2) per day) and cyclophosphamide (250 mg/m(2) per day) for the first 3 days of each 28-day treatment course with or without rituximab (375 mg/m(2) on day 0 of first course, and 500 mg/m(2) on day 1 of second to sixth courses) in 190 centres in 11 countries. Investigators and patients were not masked to the computer-generated treatment assignment. The primary endpoint was progression-free survival (PFS). Analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00281918. FINDINGS: 408 patients were assigned to fludarabine, cyclophosphamide, and rituximab (chemoimmunotherapy group) and 409 to fludarabine and cyclophosphamide (chemotherapy group); all patients were analysed. At 3 years after randomisation, 65% of patients in the chemoimmunotherapy group were free of progression compared with 45% in the chemotherapy group (hazard ratio 0·56 [95% CI 0·46-0·69], p<0·0001); 87% were alive versus 83%, respectively (0·67 [0·48-0·92]; p=0·01). Chemoimmunotherapy was more frequently associated with grade 3 and 4 neutropenia (136 [34%] of 404 vs 83 [21%] of 396; p<0·0001) and leucocytopenia (97 [24%] vs 48 [12%]; p<0·0001). Other side-effects, including severe infections, were not increased. There were eight (2%) treatment-related deaths in the chemoimmunotherapy group compared with ten (3%) in the chemotherapy group. INTERPRETATION: Chemoimmunotherapy with fludarabine, cyclophosphamide, and rituximab improves progression-free survival and overall survival in patients with chronic lymphocytic leukaemia. Moreover, the results suggest that the choice of a specific first-line treatment changes the natural course of chronic lymphocytic leukaemia. FUNDING: F Hoffmann-La Roche.


Subject(s)
Antibodies, Monoclonal/administration & dosage , Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Leukemia, Lymphocytic, Chronic, B-Cell/drug therapy , Adult , Aged , Aged, 80 and over , Antibodies, Monoclonal/adverse effects , Antibodies, Monoclonal, Murine-Derived , Antineoplastic Combined Chemotherapy Protocols/adverse effects , Cyclophosphamide/administration & dosage , Disease Progression , Disease-Free Survival , Drug Administration Schedule , Female , Humans , Immunologic Factors/administration & dosage , Incidence , Kaplan-Meier Estimate , Leukemia, Lymphocytic, Chronic, B-Cell/mortality , Leukopenia/chemically induced , Male , Middle Aged , Neutropenia/chemically induced , Rituximab , Severity of Illness Index , Treatment Outcome , Vidarabine/administration & dosage , Vidarabine/analogs & derivatives
14.
Leukemia ; 23(3): 519-27, 2009 Mar.
Article in English | MEDLINE | ID: mdl-19092852

ABSTRACT

Differential expression of molecules in chronic lymphocytic leukemia (CLL) may define prognostic markers and suitable targets for immunotherapy. Expression of the tumor-associated antigen (TAA) RHAMM (receptor for hyaluronic acid-mediated motility) as well as RHAMM splicing variants was assessed in series of 72 CLL patients. Quantitative reverse transcriptase PCR showed higher RHAMM expression in high-risk CLL patients, as well as in the advanced stages of the disease. CLL cases with a higher RHAMM expression showed a significantly shorter median treatment-free survival. Among patients with mutated immunoglobulin heavy chain genes, an analysis of RHAMM expression enabled to distinguish subgroup of patients with favorable prognosis. In lymph nodes, RHAMM staining correlated with a higher Ki-67 index and CD40L expression. Functionally, stimulation with CD40L enhanced RHAMM expression in CLL. We further characterized RHAMM-specific CD8(+) T cells in patients with CLL, as the expression of TAAs might influence the clinical outcome by the means of immune reactions. The cytotoxic potential of RHAMM-specific T cells was shown against target cells bearing RHAMM-derived epitope as well as against CLL cells expressing RHAMM. In conclusion, RHAMM expression appears to be of prognostic value, as well as may reflect the proliferative capacity of CLL cells, and might therefore represent interesting target for immunotherapy.


Subject(s)
Extracellular Matrix Proteins/physiology , Hyaluronan Receptors/physiology , Leukemia, Lymphocytic, Chronic, B-Cell/metabolism , Neoplasm Proteins/physiology , Adult , Aged , Aged, 80 and over , CD40 Ligand/analysis , CD40 Ligand/pharmacology , CD8-Positive T-Lymphocytes/immunology , CD8-Positive T-Lymphocytes/pathology , Cell Division , Cytotoxicity, Immunologic , Disease Progression , Disease-Free Survival , Extracellular Matrix Proteins/analysis , Female , Humans , Hyaluronan Receptors/analysis , Immunoglobulin Heavy Chains/genetics , Leukemia, Lymphocytic, Chronic, B-Cell/genetics , Leukemia, Lymphocytic, Chronic, B-Cell/mortality , Leukemia, Lymphocytic, Chronic, B-Cell/pathology , Male , Middle Aged , Neoplasm Proteins/analysis , Prognosis , Protein Isoforms/analysis , Protein Isoforms/physiology , RNA Splicing , Reverse Transcriptase Polymerase Chain Reaction
15.
Pain ; 135(3): 280-290, 2008 Apr.
Article in English | MEDLINE | ID: mdl-17664042

ABSTRACT

Microinjection of neurotensin (NT) into the rostral ventromedial medulla (RVM) produces dose-dependent antinociception. Here we show that antinociception produced by intra-RVM microinjection of neurotensin (NT) or the selective NT receptor subtype 1 (NTR1) agonist PD149163 can be partially blocked by intrathecal (i.t.) yohimbine, an alpha2-adrenoceptor antagonist and by methysergide, a serotonin receptor antagonist. Antinociception produced by the NTR2 agonist beta-lactotensin (beta-LT) is blocked by intrathecal (i.t.) yohimbine, but not by methysergide i.t. It is not known which noradrenergic cell group is involved in this newly identified noradrenergic component of NTR-mediated antinociception. These experiments provide the first evidence that selective activation of NTR2 in the RVM produces antinociception. These results also provide evidence that activation of NTR1 in the RVM produces antinociception through spinal release of norepinephrine (NE) and serotonin, and that activation of NTR2 in the RVM produces antinociception mediated by spinal release of NE.


Subject(s)
Medulla Oblongata/metabolism , Neurotensin/metabolism , Norepinephrine/metabolism , Pain/metabolism , Receptors, Neurotensin/metabolism , Spinal Cord/metabolism , Adrenergic alpha-Antagonists/pharmacology , Analgesics/metabolism , Analgesics/pharmacology , Animals , Efferent Pathways/drug effects , Efferent Pathways/metabolism , Male , Medulla Oblongata/anatomy & histology , Medulla Oblongata/drug effects , Microinjections , Neurons/drug effects , Neurons/metabolism , Neurotensin/analogs & derivatives , Neurotensin/pharmacology , Pain/drug therapy , Pain/physiopathology , Posterior Horn Cells/drug effects , Posterior Horn Cells/metabolism , Presynaptic Terminals/metabolism , Rats , Rats, Sprague-Dawley , Receptors, Neurotensin/agonists , Reticular Formation/drug effects , Reticular Formation/metabolism , Serotonin Antagonists/pharmacology , Spinal Cord/drug effects
16.
Pain ; 114(1-2): 285-94, 2005 Mar.
Article in English | MEDLINE | ID: mdl-15733655

ABSTRACT

Microinjection of neurotensin (NT) in the rostral ventromedial medulla (RVM) produces dose-dependent antinociception. The NTR1 (Neurotensin Receptor Subtype 1) may mediate part of this response, however definitive evidence is lacking, and the spinal mediators of NTR1-induced antinociception are unknown. In the present study, we used immunohistochemical techniques to show that the NTR1, but not the NTR2 is expressed by spinally projecting serotonergic neurons of the RVM. We also show that microinjection of NT or the NTR1-selective agonist PD149163 in the RVM both produce dose-dependent antinociception in the tail-flick test that is blocked by the NTR1-selective antagonist SR48692. The antinociception produced by NT or PD149163 is also blocked by intrathecal administration of the non-selective serotonergic receptor antagonist methysergide. The results of these experiments provide anatomical and behavioral evidence that activation of NTR1-expressing spinally projecting neurons in the RVM produces antinociception through release of serotonin in the spinal dorsal horn. These results support the conclusion that the NTR1 plays an important role in the central modulation of nociception.


Subject(s)
Analgesics/pharmacology , Medulla Oblongata/drug effects , Neurotensin/pharmacology , Receptors, Neurotensin/metabolism , Serotonin/metabolism , Spinal Cord/drug effects , Animals , Dose-Response Relationship, Drug , Male , Medulla Oblongata/metabolism , Microinjections , Neurons/drug effects , Neurons/metabolism , Neurotensin/administration & dosage , Pain Measurement/drug effects , Pain Measurement/methods , Rats , Rats, Sprague-Dawley , Receptors, Neurotensin/agonists , Spinal Cord/metabolism
17.
Brain Res ; 1016(1): 12-9, 2004 Jul 30.
Article in English | MEDLINE | ID: mdl-15234247

ABSTRACT

Activation of neurons in the rostral ventromedial medulla (RVM) directly modulates spinal nociceptive transmission by projections to the spinal cord dorsal horn and indirectly by projections to neurons in the dorsolateral pons (DLP) that project to the spinal cord dorsal horn. However, it is not known whether the same neurons in the RVM produce both direct and indirect modulation of nociception. Deposits of the retrograde tracers Fluoro-Gold (FG) in the spinal cord dorsal horn and DiI in the DLP were used to determine whether the same RVM neurons project to both of these regions. Only 0.9+/-0.1% of RVM neurons retrogradely labeled with Fluoro-Gold from the spinal cord were also labeled with DiI placed in the DLP. In addition, spinally projecting RVM neurons were significantly larger than RVM neurons that project to the DLP. Finally, spinally projecting neurons were found predominantly on the midline and within the RVM; neurons that project to the DLP had a wider distribution and were present both within and outside of the RVM. Thus, separate and morphologically distinct populations of RVM neurons appear to modulate nociception by direct and indirect descending pathways.


Subject(s)
Medulla Oblongata/cytology , Neural Pathways/physiology , Neurons/physiology , Pons/cytology , Spinal Cord/cytology , Animals , Carbocyanines , Cell Count/methods , Cell Size/physiology , Fluorescent Dyes , Male , Neurons/chemistry , Neurons/classification , Rats , Rats, Sprague-Dawley , Stilbamidines
18.
J Neurophysiol ; 87(1): 548-57, 2002 Jan.
Article in English | MEDLINE | ID: mdl-11784770

ABSTRACT

GABAergic interneurons in the hippocampus express high levels of alpha7 nicotinic acetylcholine receptors, but because of the diverse roles played by hippocampal interneurons, the impact of activation of these receptors on hippocampal output neurons (i.e., CA1 pyramidal cells) is unclear. Activation of hippocampal interneurons could directly inhibit pyramidal neuron activity but could also produce inhibition of other GABAergic cells leading to disinhibition of pyramidal cells. To characterize the inhibitory circuits activated by these receptors, exogenous acetylcholine was applied directly to CA1 interneurons in hippocampal slices, and the resulting postsynaptic responses were recorded from pyramidal neurons or interneurons. Inhibitory currents mediated by GABA(A) receptors were observed in 27/131 interneuron/pyramidal cell pairs, but no instances of disinhibition of spontaneous inhibitory events or GABA(B) receptor-mediated responses were observed. Two populations of bicuculline-sensitive GABA(A) receptor-mediated currents could be distinguished based on their kinetics and amplitude. Anatomical reconstructions of the interneurons in a subset of connected pairs support the hypothesis that these two populations correspond to inhibitory synapses located either on the somata or dendrites of pyramidal cells. In 11 interneuron/interneuron cell pairs, one presynaptic neuron was observed that produced strong inhibitory currents in several nearby interneurons, suggesting that disinhibition of pyramidal neurons may also occur. All three types of inhibitory responses (somatic-pyramidal, dendritic-pyramidal, and interneuronal) were blocked by the alpha7 receptor-selective antagonist methyllycaconitine. These data suggest activation of these functionally distinct circuits by alpha7 receptors results in significant inhibition of both hippocampal pyramidal neurons as well as interneurons.


Subject(s)
Hippocampus/metabolism , Neural Inhibition/physiology , Neurons/metabolism , Receptors, Nicotinic/metabolism , gamma-Aminobutyric Acid/metabolism , Acetylcholine/pharmacology , Animals , Dendrites/physiology , GABA Antagonists/pharmacology , GABA-A Receptor Antagonists , Hippocampus/cytology , In Vitro Techniques , Interneurons/drug effects , Interneurons/metabolism , Male , Membrane Potentials/drug effects , Membrane Potentials/physiology , Neural Inhibition/drug effects , Neuronal Plasticity/physiology , Neurons/drug effects , Nicotinic Antagonists/pharmacology , Pyramidal Cells/drug effects , Pyramidal Cells/metabolism , Rats , Rats, Sprague-Dawley , Reaction Time/physiology , Synaptic Transmission/physiology , alpha7 Nicotinic Acetylcholine Receptor
19.
Neuroscience ; 106(1): 55-67, 2001.
Article in English | MEDLINE | ID: mdl-11564416

ABSTRACT

GABAergic interneurons have been shown to be a major target of cholinergic inputs to the hippocampus. Because these interneurons project to pyramidal neurons as well as other interneurons, activation of the cholinergic system is likely to produce a complex modulation of local inhibitory activity. To better understand the role of post-synaptic alpha7 nicotinic acetylcholine receptors in the hippocampus, we have characterized the effects of nicotinic agents on local interneurons of the rat CA1 stratum oriens in terms of activation, desensitization, and region of axonal termination. Fast application of acetylcholine onto stratum oriens interneurons during whole-cell recordings from hippocampal slices activated the majority of cells tested, and these responses were mediated almost entirely by alpha7 nicotinic acetylcholine receptors. Anatomical reconstructions showed no clear relationship between the acetylcholine responsivity of interneurons and the regions to which their axons project. Currents mediated by alpha7 receptors declined markedly during repetitive activation in the theta rhythm range (4-12 Hz) when activated by either pressure application or synaptic release of acetylcholine. However, the decay of alpha7 receptor-mediated currents was unaffected by treatment with the cholinesterase inhibitor neostigmine (10 nM-10 microM), suggesting that hydrolysis of acetylcholine is not a rate-limiting step in the termination of these responses. From these findings we suggest that nicotinic receptor activity in this region has an extensive and complex impact on local inhibitory circuits that is mediated by activation of several classes of intrinsic GABAergic cells. In addition, desensitization of the alpha7 nicotinic acetylcholine receptor is likely to contribute to the decay of individual responses to pressure application of agonist, and may also act in a cumulative fashion to impair the ability of these receptors to support repetitive activity during trains of activation. If applicable to alpha7 receptor responses in vivo, we suggest it may be difficult to enhance these responses for therapeutic purposes with cholinesterase inhibitors.


Subject(s)
Acetylcholine/metabolism , Action Potentials/physiology , Hippocampus/metabolism , Interneurons/metabolism , Lysine/analogs & derivatives , Pyramidal Cells/metabolism , Receptors, Nicotinic/metabolism , Acetylcholine/pharmacology , Acetylcholinesterase/drug effects , Acetylcholinesterase/metabolism , Action Potentials/drug effects , Animals , Cholinesterase Inhibitors/pharmacology , Electric Stimulation , Excitatory Amino Acid Antagonists/pharmacology , GABA Antagonists/pharmacology , Hippocampus/cytology , Hippocampus/drug effects , Interneurons/cytology , Interneurons/drug effects , Lysine/metabolism , Male , Nicotinic Agonists/pharmacology , Nicotinic Antagonists/pharmacology , Purinergic P2 Receptor Antagonists , Pyramidal Cells/cytology , Pyramidal Cells/drug effects , Rats , Rats, Sprague-Dawley , Receptors, Nicotinic/drug effects , Receptors, Purinergic P2/metabolism , Serotonin Antagonists/pharmacology , Synaptic Transmission/drug effects , Synaptic Transmission/physiology , Theta Rhythm/drug effects , alpha7 Nicotinic Acetylcholine Receptor , gamma-Aminobutyric Acid/metabolism
20.
Phys Rev Lett ; 85(18): 3958-61, 2000 Oct 30.
Article in English | MEDLINE | ID: mdl-11041970

ABSTRACT

Bound states made from two triplet excitations on the Shastry-Sutherland lattice are investigated. Based on the perturbative unitary transformation by flow equations quantitative properties like dispersions and qualitative properties like symmetries are determined. The high order results [up to (J2/J1)(14)] permit one to fix the parameters of SrCu2(BO3)(2) precisely: J1 = 6.16(10) meV, x J2/J1 = 0.603(3), J( perpendicular) = 1.3(2) meV. At the border of the magnetic Brillouin zone a general double degeneracy is derived. An unexpected instability in the triplet channel at x = 0.63 indicates a transition towards another phase. The possible nature of this phase is discussed.

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