Spinal microglial activation in rat models of neuropathic and osteoarthritic pain: an autoradiographic study using [3H]PK11195.

BACKGROUND: Microglia serve as macrophage-like cells in the central nervous system, and activation of microglial cells in the spinal cord may contribute to ongoing pain following peripheral trauma or nerve injury. Following pronociceptive stimulation, activated microglia exhibit increased expression of the peripheral benzodiazepine receptor (PBR)/translocator protein 18 kDa (TSPO). METHODS: Using radioligand binding autoradiography and filtration assays, we examined the specific binding of the PBR/TSPO ligand [(3)H]PK11195 in spinal cords from the following rat experimental pain models: neuropathic pain induced by spinal nerve ligation (SNL), osteoarthritic pain induced by intraarticular injection of monosodium iodoacetate in the knee joint (MIA-OA), and subchronic inflammatory pain induced by intraplantar injection of complete Freund's adjuvant (CFA). RESULTS: Specific [(3)H]PK11195 binding in dorsal and ventral regions of lumbar spinal cord was increased by ≥70% ipsilateral to SNL. Also, specific [(3)H]PK11195 binding in the ipsilateral (injured) lumbar spinal cord was increased by approximately 25% in MIA-OA. In contrast to the data obtained in these chronic neuropathic and nociceptive pain models, specific [(3)H]PK11195 binding in the ipsilateral (injured) dorsal horn was elevated in only one of six CFA rats. Consistent with increased PBR/TSPO binding measured for SNL and MIA-OA rats, increased anti-OX-42 immunostaining of the cell surface microglial marker CD11b was observed in the ipsilateral spinal cord from these models. CONCLUSIONS: These studies demonstrate that [(3)H]PK11195 binding assays may serve as a marker of spinal microglial activation in experimental models of chronic neuropathic or osteoarthritic pain, which may be translatable to clinical research through novel applications of PBR/TSPO imaging agents.

[Pediatric hyperglycemic hyperosmolar coma diabeticum: diagnostic evaluation and therapeutic concept]. / Das hyperglykämisch-hyperosmolare Coma diabeticum im Kindesalter: Diagnostische Abgrenzung und Therapiekonzept.

Hyperglycemic hyperosmolar coma diabeticum (HHS) is a rare phenomenon in pediatric patients. It causes major morbidity and significant mortality. It is characterized by the trias of hyperglycemia, hyperosmolality and absent or mild metabolic acidosis. Major complications include cerebral edema and rhabdomyolysis. Evidence based guidelines for HHS in children are lacking. Based on a literature review we discuss treatment options in pediatric HHS und suggest a therapeutic concept. Appropriate treatment consists of adequate fluid administration and a cautious lowering of the serum glucose level. Patients should be treated on an intensive care unit and monitored closely to avoid complications. Low-dose and late insulin administration seems to be favourable.

In vitro and in vivo characterization of A-940894: a potent histamine H4 receptor antagonist with anti-inflammatory properties.

BACKGROUND AND PURPOSE: The histamine H4 receptor is widely expressed in cells of immune origin and has been shown to play a role in a variety of inflammatory processes mediated by histamine. In this report, we describe the in vitro and in vivo anti-inflammatory properties of a potent histamine H4 receptor antagonist, A-940894 (4-piperazin-1-yl-6,7-dihydro-5H-benzo[6,7]cyclohepta[1,2-d]pyrimidin-2-ylamine). EXPERIMENTAL APPROACH: We have analysed the pharmacological profile of A-940894 at mouse native, rat recombinant and human recombinant and native, histamine H4 receptors by radioligand binding, calcium mobilization, mast cell shape change, eosinophil chemotaxis assays and in the mouse model of zymosan-induced peritonitis. KEY RESULTS: A-940894 potently binds to both human and rat histamine H4 receptors and exhibits considerably lower affinity for the human histamine H1, H2 or H3 receptors. It potently blocked histamine-evoked calcium mobilization in the fluorometric imaging plate reader assays and inhibited histamine-induced shape change of mouse bone marrow-derived mast cells and chemotaxis of human eosinophils in vitro. In a mouse mast cell-dependent model of zymosan-induced peritonitis, A-940894 significantly blocked neutrophil influx and reduced intraperitoneal prostaglandin D2 levels. Finally, A-940894 has good pharmacokinetic properties, including half-life and oral bioavailability in rats and mice. CONCLUSIONS AND IMPLICATIONS: These data suggest that A-940894 is a potent and selective histamine H4 receptor antagonist with pharmacokinetic properties suitable for long-term in vivo testing and could serve as a useful tool for the further characterization of histamine H4 receptor pharmacology.

Differential effects of cannabinoid receptor agonists on regional brain activity using pharmacological MRI.

BACKGROUND AND PURPOSE: Activation of cannabinoid CB1 and/or CB2 receptors mediates analgesic effects across a broad spectrum of preclinical pain models. Selective activation of CB2 receptors may produce analgesia without the undesirable psychotropic side effects associated with modulation of CB1 receptors. To address selectivity in vivo, we describe non-invasive, non-ionizing, functional data that distinguish CB1 from CB2 receptor neural activity using pharmacological MRI (phMRI) in awake rats. EXPERIMENTAL APPROACH: Using a high field (7 T) MRI scanner, we examined and quantified the effects of non-selective CB1/CB2 (A-834735) and selective CB2 (AM1241) agonists on neural activity in awake rats. Pharmacological specificity was determined using selective CB1 (rimonabant) or CB2 (AM630) antagonists. Behavioural studies, plasma and brain exposures were used as benchmarks for activity in vivo. KEY RESULTS: The non-selective CB1/CB2 agonist produced a dose-related, region-specific activation of brain structures that agrees well with published autoradiographic CB1 receptor density binding maps. Pretreatment with a CB1 antagonist but not with a CB2 antagonist, abolished these activation patterns, suggesting an effect mediated by CB1 receptors alone. In contrast, no significant changes in brain activity were found with relevant doses of the CB2 selective agonist. CONCLUSION AND IMPLICATIONS: These results provide the first clear evidence for quantifying in vivo functional selectivity between CB1 and CB2 receptors using phMRI. Further, as the presence of CB2 receptors in the brain remains controversial, our data suggest that if CB2 receptors are expressed, they are not functional under normal physiological conditions.

The laterodorsal tegmentum contributes to behavioral sensitization to amphetamine.

A critical event in the development of behavioral sensitization is a transient increase in excitatory drive to dopamine neurons of the ventral tegmental area (VTA). This is likely to be due, in part, to the ability of drugs of abuse to produce long-term potentiation, expressed as increased AMPA receptor transmission, at excitatory synapses onto VTA dopamine neurons. We investigated the role of the laterodorsal tegmentum (LDT) in behavioral sensitization because LDT neurons provide an important source of excitatory drive to VTA dopamine neurons, through mixed glutamate and cholinergic inputs. To test the role of the LDT in amphetamine sensitization, ibotenic acid or sham lesions of the LDT were performed 1 week before the first of six daily amphetamine injections. When challenged with amphetamine 13 days after the last injection, sham rats expressed sensitization of stereotypy and post-stereotypy locomotor hyperactivity, whereas the latter was attenuated by ibotenic acid lesions of the LDT. To determine whether plasticity occurs in the LDT during amphetamine sensitization, we used a previously developed microdialysis assay in which increased ability of AMPA to activate a pathway serves as a marker for long-term potentiation. Two days after discontinuing repeated saline or amphetamine injections, the responsiveness of LDT-VTA neurons to AMPA was determined by microinjecting AMPA (0.4 nmol) into the LDT and measuring glutamate efflux in the ipsilateral VTA. Glutamate efflux was transiently increased in both groups but a delayed group difference was apparent with relatively higher glutamate efflux in amphetamine rats 30-60 min after AMPA injection. In parallel experiments, dopamine efflux in the nucleus accumbens (NAc) following intra-LDT AMPA declined in saline rats but remained relatively stable in amphetamine rats. Both results suggest relatively greater excitability of the LDT-VTA-NAc pathway after repeated amphetamine treatment. Our results provide the first evidence that neuronal plasticity in the LDT contributes to behavioral sensitization.

Transposition of the great arteries associated with ventricular septal defect: surgical results and long-term outcome.

OBJECTIVES: To identify potential risk factors influencing early and late outcome following the arterial switch operation (ASO) for transposition of the great arteries associated with ventricular septal defect including double-outlet right or left ventricle. METHODS: All patients who underwent ASO in our department until August 2000 (n=105) were included in this study. There were 77 transpositions of the great arteries with ventricular septal defect, 22 Taussig-Bing hearts and six patients with double-outlet morphology. The median age at operation was 24 days. Aortic arch obstruction was present in 25 patients; in 13 of these patients, a repair with aortic arch reconstruction was done before ASO. The usual coronary artery pattern was present in 59% of the patients. In six patients, we found an intramural course of at least one coronary artery. The ventricular septal defect was closed with a patch through the right atrium (n=35), the aorta (n=25), the pulmonary artery (n=25) or the right ventricle (n=3); in 17 patients a combined approach was necessary. RESULTS: There were five hospital deaths (4.7%, 95% confidence limit 2-11%). The median duration of follow-up was 72 months. Fourteen patients underwent 15 reoperations 33 months after repair (median), eight for right ventricular outflow tract obstruction or neopulmonary stenosis. Four late deaths occurred, two due to complications related to coronary artery anomalies. Statistical analysis revealed no significant risk factor whatsoever correlating with death or need for reoperation. Survival after 12 years was 91.6%, and freedom from reoperation was 82.6%. Latest follow-up data showed that 13% of patients were in NYHA class II and/or required medical treatment; 87% were in NYHA class I. CONCLUSIONS: ASO associated with patch closure of ventricular septal defect can be performed early in life with a low risk of mortality (<5%), low incidence of reintervention (<15%) and promising long-term outcome.

Oligomerization mediated by a helix-loop-helix-like domain of baculovirus IE1 is required for early promoter transactivation.

IE1 is a principal transcriptional regulator of Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV). Transactivation by IE1 is stimulated when early viral promoters are cis linked to homologous-region (hr) enhancer sequences of AcMNPV. This transcriptional enhancement is correlated with the binding of IE1 as a dimer to the 28-bp palindromic repeats comprising the hr enhancer. To define the role of homophilic interactions in IE1 transactivation, we have mapped the IE1 domains required for oligomerization. We report here that IE1 oligomerizes by a mechanism independent of enhancer binding, as demonstrated by in vitro pull-down assays using fusions of IE1 (582 residues) to the C terminus of glutathione S-transferase. In vivo oligomerization of IE1 was verified by immunoprecipitation of IE1 complexes from extracts of plasmid-transfected SF21 cells. Analyses of a series of site-directed IE1 insertion mutations indicated that a helix-loop-helix (HLH)-like domain extending from residue 543 to residue 568 is the primary determinant of oligomerization. Replacement of residues within the hydrophobic face of the putative dimerization domain disrupted IE1 homophilic interactions and caused loss of IE1 transactivation of hr-dependent promoters in plasmid transfection assays. Thus, oligomerization is required for IE1 transcriptional stimulation. HLH mutations also reduced IE1 stability and abrogated transactivation of non-hr-dependent promoters. These data support a model wherein IE1 oligomerizes prior to DNA binding to facilitate proper interaction with the symmetrical recognition sites within the hr enhancer and thereby promote the transcription of early viral genes.

The fate of small-diameter homografts in the pulmonary position.

BACKGROUND: Limited durability is expected for small homograft valves that are used to correct congenital cardiac disease. METHODS: All 76 homograft valves with an internal annulus diameter ranging from 8 to 13 mm that were implanted from 1987 through 2000 in the pulmonary position were retrospectively analyzed. In each case, homograft size was normalized to the patient's body surface area: z-value. For 93% (14 of 15) of the 8 to 9 mm grafts, z was less than 2. For 56% (5 of 9) of the 10 mm grafts and 98% (51 of 52) of the 11 to 13 mm allografts, z was greater than 2. Survival and freedom from complications were estimated by the Kaplan-Meier method. Homograft failure was defined as homograft replacement or late death; significant dysfunction, as homograft obstruction with an echo-Doppler gradient greater than 50 mm Hg or grade III or IV valvular insufficiency. The log-rank test was used to compare outcomes. RESULTS: Seven patients died early after operation; three, late. Survival was 86.5% +/- 3.8% at 1 year and remained stable during the succeeding years. Freedom from failure for all homografts was 90.6% +/- 3.7%, 71.8% +/- 6.9%, and 61.8% +/- 9.0% at 1, 5, and 10 years, respectively. Corresponding freedom from significant dysfunction was 87.6% +/- 4.1%, 51.2% +/- 7.4%, and 10.1% +/- 8.3%. The smaller homografts (z less than 2) failed and deteriorated faster (p < 0.0001): only 32.1% +/- 13.0% were still functioning at 24 months. The larger grafts (z at least 2) retained function for the first 4 years, and 73.7% +/- 10.4% had not yet failed at 10 years. CONCLUSIONS: Smaller (z less than 2) homografts (the great majority of 8 to 9 mm grafts) have to be replaced early, usually within 2 years of implantation. Larger (z at least 2) grafts (nearly all 11 to 13 mm grafts) show remarkable durability and are suitable valved conduits for establishing right ventricle to pulmonary artery continuity in neonates and young infants.

Closure of the zone of apposition at correction of complete atrioventricular septal defect improves outcome.

OBJECTIVE: Outcome after correction of atrioventricular septal defect depends to a great deal on the postoperative function of the left atrioventricular valve. The related role of the zone of apposition ('cleft') has been debated: should it be closed (bileaflet repair) or should it be left untouched (trileaflet repair)? This study aims to answer the question by comparing the outcome of patients treated according to these two approaches. METHODS: We reviewed all our patients who underwent repair of complete atrioventricular septal defect from 1984 to 1997 and selected those in whom the closure of the zone of apposition in principle would have been possible. Two groups with similar characteristics were constituted: group I (n=63), where the zone of apposition was deliberately not closed as part of a trileaflet repair (postoperative open zone of apposition) and group II (n=96), where it was electively closed as part of a bileaflet AV valve repair (closed zone of apposition). Since we changed from a trileaflet to a bileaflet repair in 1987, the two groups differ in terms of size and length of follow-up. Outcome was compared with regard to survival and freedom from reoperation for left atrioventricular valve incompetence. Late atrioventricular valve function was evaluated by Echo-Doppler. For statistical analysis, we used Chi-square or Fisher's exact test, the Mann-Whitney test and the log-rank test for comparison of Kaplan-Meier curves. The difference was considered statistically significant with a P-value of 0.05 or less. RESULTS: Early mortality was 9.5% (6/63) in group I and 3.1% (3/96) in group II (P=0.16). Actuarial survival after 1, 4 and 8 years was 80.4, 68.4 and 64.8%, respectively, for group I. Actuarial survival for group II was 94.7, 92.1 and 92.1% (P=0.0002). Freedom from reoperation for left atrioventricular valve regurgitation was 90.2, 85.6 and 77.8% for group I at the same time interval. It was a constant 97.9% for group II (P=0.0016). At reoperation, left atrioventricular valve regurgitation was present through the open zone of apposition in 63% of group I cases. The follow-up is 96% (126/131) complete. An increase in degree of left atrioventricular valve incompetence was noted in 28% (11/39) of group I cases and in 9% (8/87) of group II cases (P=0.0131). CONCLUSION: This study demonstrates the advantage of closing the zone of apposition ('cleft') as part of repair of complete atrioventricular septal defect. Survival, freedom from reoperation for left atrioventricular valve incompetence and over-all outcome were more favourable in patients of group II. The zone of apposition should be surgically addressed whenever the morphology of the left atrioventricular valve allows for closure without producing stenosis.

[Heart surgery under cardiopulmonary bypass during the neonatal period remains a high-risk procedure]. / La chirurgie cardiaque sous circulation extracorporelle dans la période néonatale comporte encore un risque non négligeable.

Congenital Heart disease with a poor prognosis has to be operated early but with an acceptable surgical risk and a good chance of survival. The aim of this study was to analyse the indications, the operative mortality and medium-term survival of neonates undergoing cardiac surgery under cardiopulmonary bypass from 1991 to 1998. Three hundred and twenty nine operations were programmed in 326 neonates, 18% (329/1805) of all open heart surgical procedures. Anatomical detransposition of the great arteries was the commonest operation (N = 226). Correction was complete (biventricular) in 97% of cases (317/326). Twenty-eight neonates died. The operative mortality was 8.5%, much higher than that of children of 3 months or over (1.5%; p < 0.0001). There were 8 late deaths, all in the first postoperative year. The overall medium-term survival rate was 88.9 +/- 1.7%. It was 100% after correction of truncus arteriosus without interruption of the aortic arch; 94.2 +/- 1.5% after anatomical detransposition; 85.7 +/- 9.4% after commissurotomy of aortic stenosis; 79.2 +/- 8.3% for all the complex forms of interruption of the aortic arch; 75 +/- 9.7% for total anomalous pulmonary venous drainage and 42.9 +/- 18.7% after the Norwood palliative procedure of hypoplastic left heart syndrome. The authors conclude that early cardiac surgery saves the large majority of neonates suffering from complex congenital cardiac disease with poor prognosis. Survival stabilises one year after the operation. Other techniques or treatments are necessary to lower present surgical risk (8.5%) to that of surgery under cardiopulmonary bypass of children over 3 months of age (1.5%).

Truncus arteriosus: ten-year experience with homograft repair in neonates and infants.

BACKGROUND: Early complete repair of truncus arteriosus with homograft reconstruction of the right ventricular outflow tract was performed and long-term results were evaluated. METHODS: Review of 46 consecutive patients with truncus arteriosus who underwent primary correction between June 1987 and May 1997 was performed. Ages ranged from 21 days to 7.2 years (median, 62 days) and weights from 1.8 to 21.5 kg (median, 3.4 kg). Ten patients were operated on before 1 month of age, 20 between 1 and 3 months, 13 between 3 months and 1 year, and 3 at an older age. Associated cardiac conditions were encountered frequently, the most common being coronary artery anomalies (n = 16), truncal valve incompetence (n = 12), and interrupted aortic arch (n = 5). The right ventricular outflow tract was reconstructed with an aortic (n = 28) or a pulmonary homograft (n = 18). RESULTS: There were two hospital deaths (4.3%). Both patients had severe truncal valve regurgitation and interrupted aortic arch together with other unfavorable conditions. Survival in uncomplicated truncus arteriosus was 100%. Follow-up was from 3 months to 10 years (mean, 36 months). There was one late death 4 months after the initial repair, presumably because of cardiac reason. Actuarial survival was 93% at 4 months and beyond. Actuarial freedom of reoperation in the 27 hospital survivors with aortic homografts was 43% at 75 months; it was 73% at 62 months in the 17 patients surviving with pulmonary homografts. CONCLUSIONS: Neonatal or early infancy complete repair is the treatment with the best potential for survival. The homograft remains our conduit of choice to establish continuity between the right ventricle and the pulmonary artery. Management of severe truncal valve incompetence remains a surgical challenge.

[Surgical repair of common truncus arteriosus with homograft. Short- and mid-term results]. / Réparation chirurgicale du tronc artériel commun à l'aide d'homogreffes. Résultats à court et à moyen terme.

Between July 1987 and July 1993, 25 consecutive children with truncus arteriosus underwent complete surgical correction with homografts. Nineteen were under 6 months of age and 4 had an associated interruption of the aortic arch. Ten pulmonary and fifteen aortic homografts were implanted. They were cryopreserved with the exception of two, fresh aortic homografts. The diameters of the homografts varied from 8 to 19 mms. Two children who had an interruption of the aortic arch, aged 24 and 31 days, died in the peroperative period. The postoperative course was uncomplicated in only 3 cases; 20 patients had complications, including 9 cardiogenic shocks and 8 pulmonary hypertensive crises. The medium-term results included one death 4 months after surgery in an infant with an interruption of the aortic arch, and 2 successful homograft replacements 3 and 12 months after the initial repair for mycotic infection in 1 case and valvular stenosis in the other. The mean follow-up of the other 20 patients was 23 months: 14 were in NYHA functional Class I, 4 are on the waiting list for replacement of their homograft for obstruction after an average period of 47 months. The authors strategy is to perform surgical correction of truncus arteriosus very early: immediately in the neonatal period in cases with uncontrollable cardiac failure, at 6 months at the latest. Small homografts make this aggressive attitude feasible, but with an operative mortality in the first 6 months of life of 10.5% (2/19).(ABSTRACT TRUNCATED AT 250 WORDS)