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Heidbüchel H, Hoogsteen J, Fagard R, Vanhees L, Ector H, Willems R, Van Lierde J. High prevalence of right ventricular involvement in endurance athletes with ventricular arrhythmias. Role of an electrophysiologic study in risk stratification. Eur Heart J 2003; 24:1473-80. [PMID: 12919770 DOI: 10.1016/s0195-668x(03)00282-3] [Citation(s) in RCA: 280] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Electrocardiographic abnormalities and premature ventricular contractions are common in athletes and are generally benign. However, the specific outcome of high-level endurance athletes with frequent and complex ventricular arrhythmias is unclear. Also, information on the predictive accuracy of different investigations in this subgroup is unknown. RESULTS We report on 46 high-level endurance athletes with ventricular arrhythmias (45 male; median age 31 years) followed-up for a median of 4.7 years. Eighty percent were cyclists. Hypertrophic cardiomyopathy or coronary abnormalities were present in < or =5%. Eighty percent of the arrhythmias had a left bundle branch morphology. Right ventricular (RV) arrhythmogenic involvement (based on a combination of multiple criteria) was manifest in 59% of the athletes, and suggestive in another 30%. Eighteen athletes developed a major arrhythmic event (sudden death in nine, all cyclists). They were significantly younger than those without event (median 23 years vs 38 years; P=0.01). Outcome could not be predicted by presenting symptoms, non-invasive arrhythmia evaluation or morphological findings at baseline. Only the induction of sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) during invasive electrophysiological testing was significantly related to outcome (RR 3.4; P=0.02). Focal arrhythmias were associated with a better prognosis than those due to reentry (P=0.02) but the mechanism could be determined in only 22 (48%). CONCLUSIONS Complex ventricular arrhythmias do not necessarily represent a benign finding in endurance athletes. An electrophysiological study is indicated for risk evaluation, both by defining inducibility and identifying the arrhythmogenic mechanism. Endurance athletes with arrhythmias have a high prevalence of right ventricular structural and/or arrhythmic involvement. Endurance sports seems to be related to the development and/or progression of the underlying arrhythmogenic substrate.
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Affiliation(s)
- Hein Heidbüchel
- University Hospital Gasthuisberg, University of Leuven, Leuven, Belgium.
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302
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Hoogerbrugge N, Willems R, Van Krieken HJ, Kiemeney LA, Weijmans M, Nagengast FM, Arts N, Brunner HG, Ligtenberg MJL. Very low incidence of microsatellite instability in rectal cancers from families at risk for HNPCC. Clin Genet 2003; 63:64-70. [PMID: 12519374 DOI: 10.1034/j.1399-0004.2003.630110.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In families at risk for hereditary non-polyposis colorectal cancer (HNPCC) that do not fulfill all clinical criteria for HNPCC, additional evidence is sought by testing cancer specimens for microsatellite instability (MSI). We investigated whether the location of a colorectal cancer (CRC) predicts the result of MSI-testing in these families. One hundred and seven patients suspected for HNPCC were offered MSI-testing. MSI-testing was positive in 6/7 patients with endometrial carcinoma and in 22/100 patients with CRC. Only one out of 22 (4%) rectal cancers was MSI-positive, and in this patient no mismatch repair (MMR) gene mutation was found. Right-sided colon carcinomas were more likely to be MSI-positive (14/37 or 38%), followed by left-sided colon carcinomas (7/4 or 17%) (p < 0.05), with 6/14 and 4/7 MMR gene mutations, respectively. The likelihood that a tumor would be MSI-positive was 3.3 times greater for right-sided than for left-sided colon cancer (OR 3.3, p < 0.05). Microsatellite instability was 8.1 times more frequent in colon cancers than in rectal cancers (p < 0.05). The presence of MSI was independently related to fulfillment of the Bethesda criteria (OR 7.0, p = 0.01). In families with multiple cases of colorectal cancer, the rectal cancers are only rarely MSI-positive. This indicates that even in families with multiple colorectal cancers, rectal cancers are most commonly of sporadic origin.
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Affiliation(s)
- N Hoogerbrugge
- Department of Human Genetics, University Medical Center Nijmegen, the Netherlands.
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303
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Roymans D, Willems R, Van Blockstaele DR, Slegers H. Nucleoside diphosphate kinase (NDPK/NM23) and the waltz with multiple partners: possible consequences in tumor metastasis. Clin Exp Metastasis 2002; 19:465-76. [PMID: 12405283 DOI: 10.1023/a:1020396722860] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Tumor metastasis is responsible for a high degree of mortality in cancer patients. One of the genes involved in tumor metastasis is NM23. At present, eight human isoforms, transcribed from different NM23 genes, have been detected. The gene products have been identified as nucleoside diphosphate kinases (NDPKs), most of which catalyse the transfer of the gamma-phosphate of a (deoxy)nucleoside triphosphate to a (deoxy)nucleoside diphosphate. However, the function of NDPK isoforms involved in tumor metastasis cannot be explained on the basis of their phosphotransferase activity alone. At present, several other properties, like transcriptional regulation and protein kinase activity, have been assigned to these proteins. Moreover, it has also been shown that NDPKs interact with several other proteins, and binding partners of NDPKs are identified at an increasing rate. Accumulating evidence indicates that protein-protein interactions modulate the molecular action of NDPKs. In this review we provide a brief overview of how NDPKs are correlated with cancer, and discuss when and how the activities assigned to NDPKs may affect metastasis, with special emphasis on the role of protein-NDPK interactions in this process.
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Affiliation(s)
- D Roymans
- Department of Biomedical Sciences, University of Antwerp, Antwerpen, Belgium
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304
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Abstract
BACKGROUND Catheter based "maze" procedures for atrial fibrillation have been hampered by difficult creation and evaluation of continuous and transmural linear lesions. Our aim was to develop an online evaluation method for effective lesion creation based on conventional techniques and using the multipolar ablation catheter, already in place. METHODS AND RESULTS We created 15 linear lines in right atria of 13 anesthetized sheep using three multipolar catheter designs (8 x 4 mm 7 Fr, 4 x 6 mm 7 Fr, 8 x 4 mm 3.7 Fr). The lesions were placed on the right posterolateral wall between the orifices of the superior and inferior vena cava. Radiofrequency energy was applied in the temperature-controlled mode to prespecified endpoints (electrogram amplitude decrease to < or = 50%; pacing threshold increase by > or = 100%; split potentials indicating conduction block). Macroscopically transmural and continuous lesions were achieved in only 3 experiments (29 +/- 12 mm x 5 +/- 1 mm), all created by 3.7 Fr octapolar catheters inserted through long sheaths. Preset temperature was reached in 96% of the electrodes (vs. 64% in the non-effective experiments; p < 0.01). Electrogram amplitude decrease (to < or = 50%) and pacing threshold increase (by > or = 100%) did not predict effectiveness. The only criterion that could reliably predict transmural continuous necrosis at histology was the development of split potentials (p < or = 0.05). CONCLUSIONS Effective creation of linear lesions is difficult. Pliable catheters that conform to the endocardial contour give the best results. The only endpoint that reliably predicted histological transmural continuous necrosis was development of split potentials indicating conduction block.
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Affiliation(s)
- Hennie van Rensburg
- Department of Cardiology, University Hospital Gasthuisberg, University of Leuven, Leuven, Belgium
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305
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van den Bogaard AE, Willems R, London N, Top J, Stobberingh EE. Antibiotic resistance of faecal enterococci in poultry, poultry farmers and poultry slaughterers. J Antimicrob Chemother 2002; 49:497-505. [PMID: 11864950 DOI: 10.1093/jac/49.3.497] [Citation(s) in RCA: 141] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The prevalence of resistance in enterococci to antibiotics, commonly used for therapy in poultry or as antimicrobial growth promoters (AMGPs), was determined in faecal samples of two chicken populations: broilers in which antibiotic and AMGP use is common and laying-hens with a low antibiotic usage. In addition faecal samples were examined from three human populations: broiler farmers, laying-hen farmers and poultry slaughterers. MICs of an extended panel of antibiotics for a randomly chosen gentamicin- or vancomycin-resistant enterococcal isolate from each faecal specimen were also determined. The prevalence of resistance for all antibiotics tested was higher in broilers than in laying-hens. Resistance in faecal enterococci of broiler farmers was for nearly all antibiotics higher than those observed in laying-hen farmers and poultry slaughterers. The overall resistance in broilers was correlated with the resistance in broiler farmers and in poultry slaughterers. No correlation between the results obtained in the laying-hens with any of the other populations was found. The 27 gentamicin-resistant isolates all showed high-level resistance to gentamicin and two of these isolates, both Enterococcus faecium, were resistant to all antibiotics tested, except vancomycin. The 73 vancomycin-resistant enterococci (VRE) isolated from the five populations belonged to four different species and in all isolates the vanA gene cluster was detected by blot hybridization. The pulsed-field gel electrophoresis (PFGE) patterns of these vancomycin-resistant enterococci were quite heterogeneous, but Enterococcus hirae isolates with the same or a closely related PFGE pattern were isolated at two farms from the broiler farmer and from broilers. Molecular characterization of vanA-containing transposons of these isolates showed that similar transposon types, predominantly found in poultry, were present. Moreover, similar vanA elements were not only found in isolates with the same PFGE pattern but also in other VRE isolated from both humans and chickens. The results of this study suggest transmission of resistance in enterococci from animals to man. For VRE this might be clonal transmission of animal strains, but transposon transfer seems to occur more commonly.
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Affiliation(s)
- A E van den Bogaard
- Laboratory of Medical Microbiology, University of Maastricht, PO Box 616, 6200 MD Maastricht, the Netherlands.
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306
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Willems R, Holemans P, Ector H, Sipido KR, Van de Werf F, Heidbüchel H. Mind the model: effect of instrumentation on inducibility of atrial fibrillation in a sheep model. J Cardiovasc Electrophysiol 2002; 13:62-7. [PMID: 11843485 DOI: 10.1046/j.1540-8167.2002.00062.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
INTRODUCTION Atrial electrical remodeling, shortening of the atrial effective refractory period (AERP) underlying atrial fibrillation (AF) has been described in different animal models. However, there remains some controversy regarding the time course of this electrical remodeling and the need for secondary factors in the development of AF. We investigated the effect of instrumentation on the inducibility of AF. We hypothesized that epicardial instrumentation could be a confounding factor that accelerates the development of AF. METHODS AND RESULTS Thirty sheep were rapidly atrially paced at 600 beats/min for 15 weeks: 15 were endocardially instrumented and paced (endo), and 15 were both endocardially and epicardially instrumented. Six of these animals were endocardially paced (sham) and 9 were epicardially paced (epi). The underlying rhythm was determined at regular intervals, and electrophysiologic study was performed. AF developed significantly faster in the epi group. After 3 weeks of pacing, the cumulative incidence of sustained AF (>1 hour) already was 70% in this group versus only 14% and 20% in the endo and sham groups, respectively. After 15 weeks of pacing, this difference was no longer evident. Baseline AERP and minimal AERP, reached before the development of AF, were not significantly different in the three groups. Epicardial instrumentation (epi and sham) increased baseline left and right atrial pressures, but only epicardial stimulation (epi) led to early development of AF. CONCLUSION In this sheep model of AF, the experimental setup is a major determinant of the inducibility of AF. Not epicardial instrumentation per se but epicardial stimulation accelerated the development of AF. Different animal models
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Affiliation(s)
- Rik Willems
- Department of Cardiology, University Hospital Gasthuisberg, University of Leuven, Belgium
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307
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Willems R, Sipido KR, Holemans P, Ector H, Van de Werf F, Heidbüchel H. Different patterns of angiotensin II and atrial natriuretic peptide secretion in a sheep model of atrial fibrillation. J Cardiovasc Electrophysiol 2001; 12:1387-92. [PMID: 11797996 DOI: 10.1046/j.1540-8167.2001.01387.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
INTRODUCTION It is well established that rapid atrial rates, as in atrial fibrillation (AF), cause atrial electrical and structural remodeling leading to the maintenance of AF. The role of neurohumoral changes in this pathophysiologic vicious circle remains unclear. METHODS AND RESULTS We followed the concentrations of angiotensin II (AT II) and atrial natriuretic peptide (ANP) in a sheep model of AF. The sheep were atrially paced at 600 beats/min for 15 weeks. Electrophysiologic study was performed at regular intervals, and venous blood samples were taken. There was a slow increase in the vulnerability for AF. The cumulative incidence of sustained AF was 80% after 15 weeks of pacing. This increased vulnerability for AF was accompanied by atrial electrical remodeling and an increase in atrial pressure. AT II increased rapidly and stayed elevated: 17+/-4 pg/mL at baseline, and 40+/-11 and 39+/-7 pg/mL after 1 and 12 weeks of pacing, respectively. ANP rose more progressively: 35+/-7 pg/mL at baseline, and 72+/-17, 95+/-10, and 106+/-23 pg/mL after 1, 3, and 12 weeks, respectively. ANP levels correlated with atrial pressure and inducibility of AF. There was no relation between these parameters and AT II levels. CONCLUSION AT II and ANP increased significantly in this animal model of AF. Elevation of AT II occurs early and seems to be dependent on rapid atrial rate rather than the presence of AF. ANP increased more progressively. It paralleled the inducibility of AF and atrial stretch. Both neurohumoral pathways may form a potential therapeutic target for treatment of patients with AF.
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Affiliation(s)
- R Willems
- Department of Cardiology, University Hospital Gasthuisberg, University of Leuven, Belgium.
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308
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Abstract
Vancomcyin-resistant enterococci (VRE) have emerged as nosocomial pathogens in the past 10 years, causing epidemiological controversy. In the USA, colonisation with VRE is endemic in many hospitals and increasingly causes infection, but colonisation is absent in healthy people. In Europe, outbreaks still happen sporadically, usually with few serious infections, but colonisation seems to be endemic in healthy people and farm animals. Vancomycin use has been much higher in the USA, where emergence of ampicillin-resistant enterococci preceded emergence of VRE, making them very susceptible to the selective effects of antibiotics. In Europe, avoparcin, a vancomycin-like glycopeptide, has been widely used in the agricultural industry, explaining the community reservoir in European animals. Avoparcin has not been used in the USA, which is consistent with the absence of colonisation in healthy people. From the European animal reservoir, VRE and resistance genes have spread to healthy human beings and hospitalised patients. However, certain genogroups of enterococci in both continents seem to be more capable of causing hospital outbreaks, perhaps because of the presence of a specific virulence factor, the variant esp gene. By contrast with the evidence of a direct link between European animal and human reservoirs, the origin of American resistance genes remains to be established. Considering the spread of antibiotic-resistant bacteria and resistance genes, the emergence of VRE has emphasised the non-existence of boundaries between hospitals, between people and animals, between countries, and probably between continents.
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Affiliation(s)
- M J Bonten
- Department of Internal Medicine and the Eijkman-Winkler Institute for Microbiology, Infectious Diseases, and Inflammation, University Medical Center Utrecht, The Netherlands.
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309
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Butter C, Hartung WM, Kay GN, Willems R, Zhang G, Lang DJ, Fleck E. Clinical validation of new pacing-sensing configurations for atrial automatic capture verification in pacemakers. J Cardiovasc Electrophysiol 2001; 12:1104-8. [PMID: 11699516 DOI: 10.1046/j.1540-8167.2001.01104.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
INTRODUCTION This study evaluated an atrial automatic capture verification scheme based on atrial evoked response (AER). Atrial pacing was between Atip and Can (Atip-Can) using different coupling capacitances (CCs). Independent pairs of sensing electrodes between Aring and Vtip (Aring-Vtip) or between Aring and a separate indifferent electrode (Aring-Indiff) were used to reduce pacing-induced afterpotentials. METHODS AND RESULTS A custom-made external pacing system was used to perform automatic step-up and step-down pacing (0.1 to 7.1 V at 0.5 msec, step size of 0.1 V) using different CCs (2 or 15 microF). Intracardiac signals from Aring-Indiff and Aring-Vtip were independently recorded and analyzed both in real time and off-line to detect AER. Every paced beat also was visually inspected and compared with surface ECG to verify the captures. With the intracardiac signals properly filtered, AER detection was based on the signal within a window of 12 to 65 msec after the stimulus. Data from 27 patients (4 chronic and 23 acute implantations; age 65.6+/-13.9 years) were analyzed. Bipolar atrial lead measurements using a standard pacing system analyzer were as follows (mean +/- SD): impedance 695+/-227 ohms, P wave amplitude 4.2+/-2.3 mV, slew rate 1.1+/-0.9 V/sec, and pacing threshold at 0.5 msec 1.0+/-0.5 V. The results with CC = 2 microF showed that of 9,500 atrial paced beats, correct capture verification rates were 99.8% (Aring-Indiff) and 99.4% (Aring-Vtip). Similar results were achieved with CC = 15 microF (99.7% and 99.5%, respectively). CONCLUSION AER can be reliably detected using independent pacing (Atip-Can) and sensing (Aring-Vtip or Aring-Indiff) electrodes. Therefore, atrial automatic capture verification by AER detection is feasible.
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Affiliation(s)
- C Butter
- Department of Cardiology, German Heart Institute Berlin & Charité.
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310
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Willems R, Ector H, Holemans P, Van De Werf F, Heidbüchel H. Effect of different pacing protocols on the induction of atrial fibrillation in a transvenously paced sheep model. Pacing Clin Electrophysiol 2001; 24:925-32. [PMID: 11449587 DOI: 10.1046/j.1460-9592.2001.00925.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In different animal models rapid atrial stimulation led to a shortening and maladaptation to rate of the atrial effective refractory period (AERP). This atrial electrical remodeling resulted in an increased vulnerability to atrial fibrillation (AF). These experimental findings formed the rationale for a stringent pursuit of sinus rhythm in patients with AF, since this would prevent or reverse atrial remodeling. This study tested the hypothesis that a reduction of arrhythmia burden would lead to a decreased vulnerability for AF. Different rapid atrial pacing protocols in a sheep model were used. During 15 weeks, 13 animals were continuously rapid paced and 7 animals were intermittently burst-paced, resulting in rapid atrial activation during 100% versus 33 +/- 4% of the time, respectively. In the continuously paced group, 77% of the animals developed sustained AF (i.e., > 1 hour) versus only 29% in the burst-paced group (P < 0.05). However, there was no difference in mean AERP shortening over time, nor maximal AERP shortening per animal, between both protocols. Minimal AERP was 103 +/- 5 ms in the continuously paced group and 107 +/- 5 in the burst-paced group (P = NS). Significant changes could be identified in effect on P wave duration, AVN function, and atrial dilation. Conduction slowing was more pronounced in the continuously paced group with a maximal P wave duration of 136 +/- 4 ms in this group versus 116 +/- 5 in the burst-paced group (P < 0.05). In the continuously paced group, the right atrial area significantly increased from 2.5 +/- 0.1 cm2 at baseline to 4.2 +/- 0.2 cm2. In the burst-paced group there was no significant atrial dilatation (from 2.6 +/- 0.1 to 2.8 +/- 0.1 cm2). In conclusion, limiting atrial arrhythmia burden slowed the development of sustained AF in this sheep model. This was not mediated by a decreased influence on atrial refractoriness but seemed to be dependent on smaller changes in atrial conduction and dimensions.
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Affiliation(s)
- R Willems
- Department of Cardiology, University Hospital Gasthuisberg, University of Leuven, Leuven, Belgium
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311
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Abstract
In view of the evolving indications for device therapy in atrial arrhythmia the accurate detection of high rate atrial events is a necessity. In a sheep model of atrial fibrillation (AF) we observed a contradictory behavior of the Thera DR pacemaker. The pacemakers were programmed to deliver burst pacing on detection of sinus rhythm (SR). Paradoxically, progressively more inappropriate bursts were delivered during AF, at a higher sensitivity. This implied that the pacemaker interpreted AF as SR. We assessed the atrial detection of the Thera DR, Diamond, Saphir, and Marathon pacemakers during AF, in a sheep model and in vitro using a waveform generator. By counting the annotated atrial-sensed events reported by the pacemaker we charted the behavior of the pacemakers at different sensitivities. At a higher sensitivity both the Thera DR and the Diamond paradoxically reported fewer atrial events during AF. This behavior led to inappropriate mode switching and incorrect diagnostic data collection. It could be reproduced in vitro. The Marathon did not show this paradoxical undersensing in vivo or in vitro. This paradoxical undersensing at a high sensitivity is dependent on the amplitude of the input signal and could not be explained by an overlap of programmable timing parameters. It is caused by ringing of the atrial sensing amplifier. At high atrial rates and a high sensitivity the ringing of the repetitive atrial signal input results in blanking of the atrial amplifier. This observation may be relevant in the device management of patients with paroxysmal AF.
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Affiliation(s)
- R Willems
- Department of Cardiology, University Hospital Gasthuisberg, University of Leuven, Leuven, Belgium
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312
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Roymans D, Vissenberg K, De Jonghe C, Willems R, Engler G, Kimura N, Grobben B, Claes P, Verbelen JP, Van Broeckhoven C, Slegers H. Identification of the tumor metastasis suppressor Nm23-H1/Nm23-R1 as a constituent of the centrosome. Exp Cell Res 2001; 262:145-53. [PMID: 11139339 DOI: 10.1006/excr.2000.5087] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Processes like cell proliferation, differentiation, and tumor metastasis require a flexible adaptation of cell shape and cell plasticity. A regulator of cell structure and shape is the centrosome and its associated microtubules. Recently, oncogenes like p53, pRB, and the tumor suppressor BRCA1 have been characterized as members of the centrosome. In this communication, we identified rat Nm23-R1/NDPKbeta, a homologue of the human tumor metastasis suppressor Nm23-H1 and a regulator of cell proliferation and differentiation, as a component of the centrosomal complex. We used confocal laser scanning microscopy on different cell types and biochemical analysis of purified centrosomes to demonstrate that Nm23-R1 is located in the centrosome of dividing and nondividing cells. We also showed that the centrosomal enzyme is catalytically active and able to transfer the gamma-phosphate from a nucleoside triphosphate to a nucleoside diphosphate. In addition, Nm23-R1 coimmunoprecipitated with gamma-tubulin, a core centrosomal protein essential for microtubule nucleation. In addition, human Nm23-R1/-H1 was also shown to be present in the centrosome of different human and rat cell types, demonstrating that the presence of Nm23-H1 homologues in the latter organelle is a general event.
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Affiliation(s)
- D Roymans
- Cellular Biochemistry, University of Antwerp, Wilrijk-Antwerpen, B-2610, Belgium
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313
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Willems R, Henckaerts E, Lenjou M, Nijs G, Rodrigus I, Moulijn AC, Slegers H, Berneman ZN, Van Bockstaele DR. Establishment of serum-free pre-colony forming unit assays for differentiation of primitive hematopoietic progenitors: serum induces early macrophage differentiation and inhibits early erythroid differentiation of CD34++CD38- cells. Ann Hematol 2001; 80:17-25. [PMID: 11233770 DOI: 10.1007/s002770000227] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
In this report we show that serum has differentiation-inducing effects on primitive hematopoietic progenitor cells with the CD34++CD38- immunophenotype. Using the pre-colony forming unit (pre-CFU) assay as a model for early myelopoiesis, we compared the effects of serum-containing and serum-free media and evaluated different cytokine cocktails [interleukin (IL)-1, IL-3, IL-6, kit ligand with and without the Flt3/Flk2 ligand (FL)]. In this assay, pre-CFUs are defined as cells unable to form colonies when plated directly in semi-solid assays, but which can differentiate into CFUs when cultured in liquid medium containing early-acting cytokines. In one of the investigated serum-free media, the average myeloid expansion in liquid medium reached up to more than 50% of that obtained in serum-containing medium. In addition, our experiments revealed differences in the clonogenic output between cells cultured in serum-free medium and those cultured in serum-containing medium, demonstrating that serum has a monocyte differentiation-inducing effect on primitive hematopoietic progenitors. Also in serum-free medium, higher proportions of erythroid progenitors were generated. These differentiation-inducing effects of serum further emphasize the need for serum-free culture protocols for hematopoietic graft engineering. Addition of FL to the culture media ameliorated cellular expansion and resulted in a decrease in the proportion of erythroid and granulocyte progenitors and an increase in the proportion of monocyte progenitors. In conclusion, this study shows that good serum-free conditions are available for differentiation assays with primitive hematopoietic progenitors and demonstrates that serum and FL have biasing effects on the initial phase of hematopoietic differentiation, favoring the monocyte lineage.
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Affiliation(s)
- R Willems
- Laboratory of Experimental Hematology, University of Antwerp, Antwerp University Hospital, Edegem, Belgium
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314
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Bonten MJ, Mascini EM, Willems R, Timmer GJ, Gaillard CA, Vandenbroucke-Grauls CM. [What is to be done with vancomycin-resistant enterococcal infections?]. Ned Tijdschr Geneeskd 2000; 144:2545-9. [PMID: 11191789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
Recently, three epidemics in Dutch hospitals were caused by vancomycin-resistant enterococci (VRE). Although the number of infections was small, spread of colonization was extensive and many infection control measures were necessary to prevent further spread. VRE are relatively avirulent bacteria. However, few, if any, antibiotics are available for treatment of infections caused by VRE and the genetic code for resistance may be transferable to other, more virulent, bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA). Although colonization and infection with MRSA have become endemic in many surrounding countries, such a situation has been prevented in the Netherlands by employing an aggressive 'search and destroy' policy. Although many questions regarding the optimal approach of VRE remain unanswered, a similar policy as employed for MRSA will not be possible. In contrast to MRSA, colonization with VRE occurs in the open population, no populations with increased risk for colonization appear to be definable and colonization cannot be eradicated. Based on common sense, a differentiated approach seems indicated in which extensive infection control measures should only be implemented when spread of a single genotype has been demonstrated. A reference laboratory should be created for uniform genotyping.
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Affiliation(s)
- M J Bonten
- Universitair Medisch Centrum Utrecht, Heidelberglaan 100, 3584 CX Utrecht.
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315
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van der Steen LF, Bonten MJ, van Kregten E, Harssema-Poot JJ, Willems R, Gaillard CA. [Vancomycin-resistant Enterococcus faecium outbreak in a nephrology ward]. Ned Tijdschr Geneeskd 2000; 144:2568-72. [PMID: 11191795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
In April 2000, an outbreak of vancomycin-resistant Enterococcus faecium (VRE) was discovered in an internal medicine/nephrology and dialysis ward of the Eemland Hospital, Amersfoort, the Netherlands. Although enterococci are considered relatively non-virulent, VRE are resistant to almost all commercially available antibiotics. Surveillance cultures were obtained from all patients at the ward, all patients visiting the dialysis ward and the environment of patients. VRE were determined and clustering of strains was analysed using molecular genotyping. In all, 12 patients were colonized with the outbreak strain. Transmission of VRE usually occurs via the hands of health care workers. The ward was closed for new admissions, patients were divided in cohorts of colonized and non-colonized patients, and rooms were disinfected after patient discharge. Infection control measures (such as handwashing and use of gloves and gowns) were enforced and prescriptions of vancomycin and cephalosporins were reduced. With these measures the outbreak could be controlled. Epidemiological analysis demonstrated that earlier admission and previous use of ciprofloxacin, amoxicillin and amoxicillin-clavulanic acid were risk factors for colonization. A nearby hospital was a possible source of this outbreak.
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Affiliation(s)
- L F van der Steen
- Universitair Medisch Centrum Utrecht, divisie Interne Geneeskunde, afd. Infectieziekten & Aids, Heidelberglaan 100, 3584 CX Utrecht
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316
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Roymans D, Willems R, Vissenberg K, De Jonghe C, Grobben B, Claes P, Lascu I, Van Bockstaele D, Verbelen JP, Van Broeckhoven C, Slegers H. Nucleoside diphosphate kinase beta (Nm23-R1/NDPKbeta) is associated with intermediate filaments and becomes upregulated upon cAMP-induced differentiation of rat C6 glioma. Exp Cell Res 2000; 261:127-38. [PMID: 11082283 DOI: 10.1006/excr.2000.5037] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Nucleoside diphosphate kinases (Nm23/NDPK) are enzymes functional in cell proliferation, differentiation, development, tumor progression, and metastasis. Nevertheless, no consensus exists about the molecular mechanism by which Nm23/NDPK isoforms exert their role in these processes. We investigated the expression of the rat Nm23-R1/NDPKbeta and Nm23-R2/NDPKalpha isoforms, homologues of the human Nm23-H1/NDPK A and Nm23-H2/NDPK B proteins, respectively, upon cAMP-induced differentiation of rat C6 glioma cells and demonstrated a differential interaction with intermediate filaments. Semiquantitative RT-PCR, immunoblotting, and flow cytometry showed a constitutive expression of both Nm23 isoforms. After induction of differentiation in C6 cells with cAMP analogs or isoproterenol, a dose-dependent 2- and 2.5-fold upregulation of the Nm23-R1 mRNA and protein, respectively, was observed. In contrast, the expression of Nm23-R2 remained unchanged. Localization of both isoforms with confocal laser scanning microscopy demonstrated a punctate reticular staining pattern for both Nm23 isoforms in the cytosol and processes of the cells which was particularly intense in the perinuclear region. In addition, while Nm23-R2 was colocalized and coimmunoprecipitated with vimentin in nondifferentiated cells, both isoforms were associated with GFAP in differentiated cells. The significance of these findings in relation to a possible function of Nm23 isoforms in cell proliferation, differentiation, and tumor-associated mechanisms is discussed.
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Affiliation(s)
- D Roymans
- Laboratory of Cellular Biochemistry, University of Antwerp, Wilrijk-Antwerpen, B-2610, Belgium
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317
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Ramdat Misier AR, Beukema WP, Oude Luttikhuis HA, Willems R. Multisite atrial pacing: an option for atrial fibrillation prevention? Preliminary results of the Dutch Dual-site Right Atrial Pacing for Prevention of Atrial Fibrillation study. Am J Cardiol 2000; 86:20K-24K. [PMID: 11084095 DOI: 10.1016/s0002-9149(00)01187-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Multisite pacing is a novel concept for the prevention of recurrent drug-refractory atrial fibrillation (AF). Two different pacing methods have been described, biatrial pacing and dual-site right atrial stimulation. The use of multisite pacing as preventive therapy for recurrences of atrial fibrillation is still under investigation. We conducted a prospective, randomized, crossover study in patients with recurrent drug-refractory AF without or with minimal structural heart disease. After implantation of a DDD pacemaker, patients were randomized to either dual-site pacing first (Group I) or single-site (high right atrium) pacing first (Group II) and, after 6 months of treatment, the device was reprogrammed to the other pacing mode. Preliminary results of 13 patients in each group are presented. Clinical characteristics of patients in both groups with respect to age, sex, left atrial dimension, left ventricular function, and New York Heart Association (NYHA) functional class were comparable. Pacing therapy was combined with antiarrhythmic drug treatment. After completion of the study protocol, the arrhythmia-free interval was not remarkably different in either group. However, the endpoint free interval (i.e., the need for electrical cardioversion because of recurrent AF lasting >24 hours, was less during dual-site pacing in Group II. Within 6 months, 43 patients enrolled in this study will have completed the protocol.
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318
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Van Tendeloo VF, Willems R, Ponsaerts P, Lenjou M, Nijs G, Vanhove M, Muylaert P, Van Cauwelaert P, Van Broeckhoven C, Van Bockstaele DR, Berneman ZN. High-level transgene expression in primary human T lymphocytes and adult bone marrow CD34+ cells via electroporation-mediated gene delivery. Gene Ther 2000; 7:1431-7. [PMID: 10981672 DOI: 10.1038/sj.gt.3301252] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The design of effective gene delivery systems for gene transfer in primary human blood cells is important both for fundamental hematopoiesis research and for cancer gene therapy strategies. Here, we evaluated electroporation as a nonviral means for transfection of activated human T lymphocytes and adult bone marrow (BM) CD34+ cells. We describe optimal culture and electroporation parameters for efficient gene delivery in prestimulated T lymphocytes (16.3 +/-1.3%), as well as 2-day cultured adult BM CD34+ cells (29.6+/-4.6%). PHA-stimulated T cells were most receptive for transfection after 48h of in vitro culture, while T cells stimulated by CD3 cross-linking and interleukin (IL)-2 achieved maximum transfection levels after 72 h of prestimulation. Kinetic analysis of EGFP expression revealed that activated T lymphocytes maintained transgene expression at high levels for a prolonged period. In addition, fresh unstimulated BM CD34+ cells were consistently transfected (5.2+/-0.4%) with minimal cytotoxicity (<5%), even without preliminary CD34+ cell purification. Both T cells and CD34+ cells retained their phenotype and functional capacity after electroporation. These results demonstrate that electroporation is a suitable nonviral transfection technique that may serve applications in gene therapy protocols using T lymphocytes or CD34+ cells.
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Affiliation(s)
- V F Van Tendeloo
- Laboratory of Experimental Hematology, Antwerp University Hospital (UIA/UZA), University of Antwerp, Belgium
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319
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Hartung WM, Hartung D, Saad H, Mittag A, Mahnkopf D, Klein HU, Willems R. The importance of right atrial pacing electrode position and pacing configuration for intra-atrial and inter-atrial conduction times. J Interv Card Electrophysiol 2000; 4:405-13. [PMID: 10936006 DOI: 10.1023/a:1009858601764] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Pace prevention of atrial tachyarrhythmias is based in part on the reduction of intra-atrial (IAA) and/or inter-atrial (IEA) conduction. We previously introduced a novel pacing mode using floating atrial ring electrodes on a VDD-lead (BIdirectional MO nophasic impulSe: BIMOS). The effects of BIMOS pacing on IAA and IEA conduction times has not been studied. In nine Merino sheep electrode catheters were placed at the His-Bundle (HBE), high right atrium (HRA), coronary sinus ostium (Cs-Os), and left lateral atrium (LLA). A VDD-lead was introduced with floating electrodes in the high and mid right atrium (Floating). IAA (S/P-HRA, S/P-Cs-Os, S/P-HBE, S/P-Floating), IEA conduction times (S/P-LLA), and P-wave duration (PD) were measured during sinus rhythm (S), during bipolar cathodal pacing (P) in the HRA, in the Cs-Os position, as well as during BIMOS floating pacing. The mean PD during S was significantly shorter than during HRA- (66. 6+/-12.8ms; vs. 116.2+/-11.1ms; p<0.05) and Cs-Os-P (66.6+/-12.8ms vs. 94.4+/-9.0ms; p<0.05). In comparison to HRA-P, BIMOS configuration lead to a significant reduction of the P-wave duration (116.2+/-11.1ms vs. 85. 4+/-8.8ms; p<0.05). During BIMOS pacing, the global atrial conduction time was significantly shorter than during pacing in the HRA and Cs-Os position. The results of this study demonstrate a clear reduction of IAA and IEA conduction times using BIMOS configurations compared to conventional HRA-P. Furthermore, BIMOS pacing produced a more homogeneous atrial activation when compared with conventional HRA- and Cs-Os-P.
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Affiliation(s)
- W M Hartung
- University Hospital Magdeburg and Institute of Medicine Technology Magdeburg, Germany.
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320
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321
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Heidbüchel H, Willems R, van Rensburg H, Adams J, Ector H, Van de Werf F. Right atrial angiographic evaluation of the posterior isthmus: relevance for ablation of typical atrial flutter. Circulation 2000; 101:2178-84. [PMID: 10801759 DOI: 10.1161/01.cir.101.18.2178] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Gaining anatomic information about the posterior isthmus is not generally part of flutter ablation procedures. We postulated that right atrial (RA) angiography could rationalize the ablation approach by revealing the conformation of the isthmus. METHODS AND RESULTS In 100 consecutive patients, biplane RA angiography was performed before ablation to guide catheter contact with the isthmus along its length. Angiography showed a wide variation in the width of the isthmus (17 to 54 mm; 31.3+/-7.9), its angle with the inferior vena cava in the right anterior oblique projection (68 degrees to 114 degrees; 90.3+/-9.0 degrees ), and its lateral position relative to the inferior vena cava in the left anterior oblique projection. A deep sub-Eustachian recess was revealed in 47%, with a mean depth of 4.3+/-2.1 mm (1.5 to 9.4). A Eustachian valve was visualized in 24%. Ablation resulted in bidirectional conduction block (which could be transient) in all, with a median of 2 dragging radiofrequency (RF) applications (2.3+/-2.5 RF applications; 57 degrees C, < or =99 seconds each). Permanent block was achieved in 99%, with a median of 3 RF applications (3.4+/-3.0). The presence of a Eustachian valve or concave isthmus was associated with statistically more RF applications; the same trend was seen for patients with deep pouches. The number of RF applications decreased statistically throughout the study, indicating a learning curve. No patient had a recurrence after a follow-up of 13+/-11 months. CONCLUSIONS Right atrial angiography reveals a highly variable isthmus anatomy, often showing particular configurations that can make ablation more laborious. Rational adaptation of the ablation approach to these anatomic findings may contribute to successful ablation.
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Affiliation(s)
- H Heidbüchel
- Department of Cardiology, University Hospital Gasthuisberg, University of Leuven, Belgium.
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322
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Neumann T, Ehrlich W, Sperzel J, Kimmel A, Willems R, Klövekorn WP, Neuzner J. [Not Available]. Herzschrittmacherther Elektrophysiol 2000; 11 Suppl 1:91-92. [PMID: 19495659 DOI: 10.1007/bf03042543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Affiliation(s)
- T Neumann
- Kerckhoff-Klinik Bad Nauheim, Bad Nauheim, Deutschland
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323
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Saad H, Willems R, Mittag A, Mahnkopf D, Goette A, Hobrack S, Reek S, Klein H, Hartung WM. [Not Available]. Herzschrittmacherther Elektrophysiol 2000; 11 Suppl 1:13-14. [PMID: 19495625 DOI: 10.1007/bf03042509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Affiliation(s)
- H Saad
- Klinik für Kardiologie, Angiologie, Pneumologie, Otto-von-Guericke-Universität, Magdeburg
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324
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Hartung WM, Saad H, Willems R, Mittag A, Mahnkopf D, Goette A, Hobrack S, Reek S, Klein H. [Not Available]. Herzschrittmacherther Elektrophysiol 2000; 11 Suppl 1:7-8. [PMID: 19495622 DOI: 10.1007/bf03042506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Affiliation(s)
- W M Hartung
- Klinik für Kardiologie, Angiologie und Pneumologie, Otto-von-Guericke-Universität, Magdeburg
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325
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Stobberingh E, van den Bogaard A, London N, Driessen C, Top J, Willems R. Enterococci with glycopeptide resistance in turkeys, turkey farmers, turkey slaughterers, and (sub)urban residents in the south of The Netherlands: evidence for transmission of vancomycin resistance from animals to humans? Antimicrob Agents Chemother 1999; 43:2215-21. [PMID: 10471567 PMCID: PMC89449 DOI: 10.1128/aac.43.9.2215] [Citation(s) in RCA: 116] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The number of vancomycin-resistant enterococci (VRE) relative to the total number of enterococci was determined in fecal samples from turkeys and three human populations in 1996, each with a different level of contact with turkeys, i.e., turkey farmers, turkey slaughterers, and (sub)urban residents. The percentage of VRE relative to the total enterococcal population (i.e., the degree of resistance) was low (2 to 4%) in all groups (except in six samples). No difference was observed between farmers who used avoparcin and those who did not. The pulsed-field gel electrophoresis (PFGE) patterns of the VRE isolates from the different populations were quite heterogeneous, but isolates with the same PFGE pattern were found among animal and human isolates, in addition to the isolates which were described previously (A. E. van den Bogaard, L. B. Jensen, and E. E. Stobberingh, N. Engl. J. Med. 337:1558-1559, 1997). Detailed molecular characterization of vanA-containing transposons from different isolates showed, that in addition to a previously reported strain, similar transposons were present in VRE isolates from turkeys and turkey farmers. Moreover, similar VanA elements were found not only in isolates with the same PFGE pattern but also in other strains from both humans and animals.
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Affiliation(s)
- E Stobberingh
- Department of Medical Microbiology, University Hospital Maastricht, Maastricht, The Netherlands.
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326
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Abstract
Fatty acids have been involved in the proliferation and differentiation of numerous cells, as mediated via peroxisome proliferator-activated receptors (PPARs) or lipid metabolites (prostaglandins, diacylglycerol). In the present study, we have investigated the effect of arachidonic acid (AA), docosahexaenoic acid (DHA) and its precursor eicosapentaenoic acid (EPA) on the differentiation of a rat uterine stromal cell line, UIII. As markers of decidualization, we have investigated morphological changes, monitored by inverted light and scanning electron microscopy. The induction of 3 proteins, desmin, hsp-25 and prolactin, which are all considered to be markers of decidualization, were analyzed by immunocytochemistry or Western blotting. Addition of AA (30 microM) to the medium of cultured cells for 48h induced cell spreading and flattening. Cells became enlarged (x 2.5) and some of them were binucleated. Using scanning electron microscopy, we confirmed these morphological changes and showed that the enlargement of the cells was followed by numerous extracellular processes, leading to an increase in cell surface area and intercellular communications. Immunocytochemistry showed that this treatment also induced the expression of desmin, which seems to direct morphological changes, beginning as a perinuclear ring and extending to the cell membrane. The time course of desmin expression was studied by Western blotting. No desmin expression was present before 4h of AA treatment. Desmin induction was maximum at 24h of treatment and plateaued thereafter. DHA and EPA (30 microM), added to the medium, failed to induce any change. However, in cells previously differentiated with AA and expressing desmin, treatment with DHA or EPA (30microM) reversed partially the action of AA, EPA being the most effective. AA also induced hsp-25, though all cells did not express this protein. A prolactin (PRL)-like factor was induced by AA, as recognized by an antibody against pituitary rPRL, and migrated as the standard. Moreover, a fragment of 16 kDa was also revealed by this antibody, suggesting that the PRL-like factor cleaved, was similar to PRL and that the PRL-like factor could be identical to PRL. In conclusion, these results show that AA is able to specifically induce the decidualization of uterine stromal cells in vitro.
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Affiliation(s)
- A Tessier-Prigent
- INSERM U352, Biochimie et Pharmacologie, INSA-Lyon, Villeurbanne, France
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327
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Geurts van Kessel A, de Bruijn D, Hermsen L, Janssen I, dos Santos NR, Willems R, Makkus L, Schreuder H, Veth R. Masked t(X;18)(p11;q11) in a biphasic synovial sarcoma revealed by FISH and RT-PCR. Genes Chromosomes Cancer 1998; 23:198-201. [PMID: 9739025 DOI: 10.1002/(sici)1098-2264(199810)23:2<198::aid-gcc15>3.3.co;2-h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The initial cytogenetic analysis of a biphasic synovial sarcoma showed an apparently normal karyotype. After FISH using chromosome X- and 18-specific probes and RT-PCR using SYT- and SSX-specific primer sets, a cryptic synovial sarcoma-associated t(X;18)(p11;q11) could be revealed. The "masked" nature of the translocation may best be explained by a two-step scenario in which a genuine t(X;18)(p11;q11) has occurred as a first step and a reverse reciprocal X;18 translocation as a second step, leaving the synovial sarcoma-associated SYT-SSX1 fusion intact. The findings further underline our previous suggestion that SYT-SSX1 fusions may correlate with a biphasic nature of the tumor. In addition, our findings indicate that, in analogy to, e.g., the Philadelphia translocation in chronic myeloid leukemia, "masked" translocations may occur in soft tissue tumors and that, as a standard, RT-PCR and/or FISH analyses should be carried out in order to provide karyotypic information that may be relevant to tumor diagnosis and/or prognosis.
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328
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van Kessel AG, de Bruijn D, Hermsen L, Janssen I, dos Santos NR, Willems R, Makkus L, Schreuder H, Veth R. Masked t(X;18)(p11;q11) in a biphasic synovial sarcoma revealed by FISH and RT-PCR. Genes Chromosomes Cancer 1998. [DOI: 10.1002/(sici)1098-2264(199810)23:2<198::aid-gcc15>3.0.co;2-k] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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329
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Willems R, Van Bockstaele DR, Lardon F, Lenjou M, Nijs G, Snoeck HW, Berneman ZN, Slegers H. Decrease in nucleoside diphosphate kinase (NDPK/nm23) expression during hematopoietic maturation. J Biol Chem 1998; 273:13663-8. [PMID: 9593706 DOI: 10.1074/jbc.273.22.13663] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The nucleoside diphosphate kinase (NDPK/nm23) isoforms H1 and H2 were localized in hematopoietic tissues. Flow cytometric analysis and enzymatic assays were used to quantify the intracellular and extracellular concentrations of NDPK. Bone marrow CD34(+) progenitors contained the highest intracellular levels of both nm23-H1 and nm23-H2. Lower levels were measured in more mature bone marrow cells, whereas peripheral blood leukocytes had the lowest expression of nm23. These data suggest a function of NDPK in early hematopoiesis and a down-regulation of NDPK upon differentiation. In addition, an up-regulation of nm23 expression was observed in lymphocytes after induction of proliferation with phytohemagglutinin. Multiparameter flow cytometry demonstrated that this up-regulation occurred during the G0/G1-transition. Flow cytometric analysis also revealed a weak surface expression of nm23 on a number of hematopoietic cell lines, which was not detected on normal hematopoietic cells. Our data also demonstrated the presence of NDPK in human plasma, probably due to a limited in vivo lysis of red blood cells.
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Affiliation(s)
- R Willems
- Laboratory of Experimental Hematology, Department of Medicine, University of Antwerp, Antwerp University Hospital (UIA/UZA), Wilrijkstraat 10, B-2650 Edegem, Belgium
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330
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Hogervorst F, Ligtenberg M, Brink G, Hageman S, Menko F, Willems R, Arts N, van't Veer L, Rutgers E. 0-8. Germ-line mutations in BRCA1 and BRCA2 are seldom found in `unilateral breast cancer only' families. Breast 1997. [DOI: 10.1016/s0960-9776(97)90589-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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331
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Ashton D, Willems R, Wynants J, Van Reempts J, Marrannes R, Clincke G. Altered Na(+)-channel function as an in vitro model of the ischemic penumbra: action of lubeluzole and other neuroprotective drugs. Brain Res 1997; 745:210-21. [PMID: 9037412 DOI: 10.1016/s0006-8993(96)01094-3] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Veratridine blocks Na(+)-channel inactivation and causes a persistant Na(+)-influx. Exposure of hippocampal slices to 10 microM veratridine led to a failure of synaptic transmission, repetitive spreading depression (SD)-like depolarizations of increasing duration, loss of Ca(+)-homeostasis, a large reduction of membrane potential, spongious edema and metabolic failure. Normalization of the amplitude of the negative DC shift evoked by high K+ ACSF 80 min after veratridine exposure was taken as the primary endpoint for neuroprotection. Compounds whose mechanisms of action includes Na(+)-channel modulation were neuroprotective (IC50-values in microM): tetrodotoxin 0.017, verapamil 1.18, riluzole 1.95, lamotrigine > or = 10, and diphenylhydantoin 16.1. Both NMDA (MK-801 and PH) and non-NMDA (NBQX) excitatory amino acid antagonists were inactive, as were NOS-synthesis inhibitor (nitro-L-arginine and L-NAME) Ca(2+)-channel blockers (cadmium, nimodipine) and a K(+)-channel blocker (TEA). Lubeluzole significantly delayed in time before the slices became epileptic, postponed the first SD-like depolarization, allowed the slices to better recover their membrane potential after a larger number of SD-like DC depolarizations, preserved Ca2+ and energy homeostasis, and prevented the neurotoxic effects of veratridine (IC50-value 0.54 microM). A concentration of lubeluzole, which was 40 x higher than its IC50-value for neuroprotection against veratridine, had no effect on repetitive Na(+)-dependent action potentials induced by depolarizing current in normal ACSF. The ability of lubeluzole to prevent the pathological consequences of excessive Na(+)-influx, without altering normal Na(+)- channel function may be of benefit in stroke.
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Affiliation(s)
- D Ashton
- Department of Neuopsychopharmacology, Jansen Research Foundation, Beerse, Belgium
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332
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Abstract
Nucleoside diphosphate kinase (NDPK/nm23) ATP/GDP phosphotransferase activity and serine autophosphorylation is inhibited by N6-mbcAMP, 8-ClcAMP and 8-BrcAMP. Inhibition of the enzymatic activity largely depends on the concentration of ATP and becomes significant at ATP concentrations up to 0.5 mM and at effector concentrations measured in C6 cells stimulated with 1 mM cAMP analogue. N6-mbcAMP is a substrate of the enzyme. DbcAMP and 0'2-mbcAMP, cAMP analogues with a modified 0'2-ribose, did not affect the NDPK activity. Cyclic AMP is only a moderate inhibitor of NDPK even at low ATP concentrations. Possible inhibitory effects of cAMP and cAMP analogues on reported extra- and intracellular functions of NDPK/nm23 are discussed.
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Affiliation(s)
- K Anciaux
- Cellular Biochemistry, Department of Biochemistry, Universitaire Instelling Antwerpen, Belgium
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333
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Lethias C, Labourdette L, Willems R, Comte J, Herbage D. Composition and organization of the extracellular matrix of vein walls: collagen networks. INT ANGIOL 1996; 15:104-13. [PMID: 8803633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
As there are few recent reports concerning the structure and exact composition of the extracellular matrix from human normal and varicose veins, we carried out comparative immunohistochemical analysis of vessel wall using conventional and confocal laser scanning immunofluorescence techniques. The present report is a rapid review of the structure and function of the 19 known collagen types and our first results on the distribution of collagen types VI, XII and XIV and laminin (glycoprotein from basement membrane) in vein walls. Type VI collagen is concentrated in the sub-endothelium and widely distributed in the media and adventice. For the first time, we demonstrated that both FACIT (fibril-associated) collagens XII and XIV were present in the vein wall, but at different anatomic sites.
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Affiliation(s)
- C Lethias
- Institut de Biologie et Chimie des Protéines, Université Claude Bernard, Lyon, France
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334
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Abstract
Pacemakers are becoming increasingly sophisticated, offering a host of new diagnostic functions. This case illustrates how some of these functions can be used to help with the diagnosis and management of patients with pacemakers who suffer from cardiac arrhythmias.
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Affiliation(s)
- K Kamalvand
- Department of Cardiology, Guy's Hospital, Guy's & St. Thomas' NHS Trust, London, United Kingdom
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335
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Willems R, Duchateau J, Magrez P, Denis R, Casimir G. Influence of hypoallergenic milk formula on the incidence of early allergic manifestations in infants predisposed to atopic diseases. Ann Allergy 1993; 71:147-50. [PMID: 8346868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
One hundred twenty-two infants at risk of atopy on the basis of IgE screening at birth and family history of atopy were studied. The occurrence of atopic manifestations was analyzed in relation to their diets during the first 3 months of age. Only the infants receiving hypoallergenic milk were protected effectively; all other regimens (humanized cow milk, hypoallergenic milk or humanized cow milk + supplements) increased the frequency of allergic symptoms (P < .07). After a 1-year follow-up, the infants fed strictly on hypoallergenic milk during their 3 first months presented allergic symptoms less frequently than other infants (P < .007).
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Affiliation(s)
- R Willems
- Department of Paediatrics Hôpital Français, Brussels, Belgium
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336
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Abstract
In hippocampal slices from guinea-pig a paired-pulse stimulation protocol was used to examine the effects of loreclezole, R-(+)-etomidate, phenobarbital and pentobarbital on orthodromic and antidromic GABAergic neuronal inhibition in the CA1 region. All four compounds increased orthodromic GABAergic inhibition, with R-(+)-etomidate and pentobarbital inducing a quantitatively larger effect than loreclezole and phenobarbital. Only R-(+)-etomidate and pentobarbital increased antidromic GABAergic inhibition. We propose that all four compounds are anticonvulsant by increasing feed-forward dendritic GABAergic inhibition, whilst only the sedative/hypnotic compounds (R-(+)-etomidate, pentobarbital) increase feedback recurrent GABAergic inhibition. Loreclezole was also shown to inhibit 'low Ca2+' and 'low Mg2+' epileptogenesis at similar concentrations to those active on inhibition. Thus loreclezole may possess other pharmacodynamic properties, beyond its ability to increase feed-forward GABAergic neuronal inhibition, which contribute to its antiepileptic action.
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Affiliation(s)
- D Ashton
- Department of Neuropsychopharmacology, Janssen Research Foundation, Beerse, Belgium
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337
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Herbage D, Willems R, Flandin F. [Evaluation of extracts of Ginkgo biloba and its constituents on the fibrillogenesis and on the stability of collagen fibrils in vitro]. Phlebologie 1991; 44:873-80. [PMID: 1666679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- D Herbage
- Institut de Biologie et Chimie des Protéines, UPR CNRS 412, Université Cl. Bernard, Villeurbanne
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338
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Herbage D, Willems R, Herbage B, Pajean C. [Interaction between collagen and various vasoactive agents. Effect on in vitro fibrillogenesis of collagen]. Phlebologie 1990; 43:743-52. [PMID: 2093933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- D Herbage
- Institut de Biologie et Chimie des Protéines, CNRS UPR 412, Villeurbanne
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339
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Ashton D, Willems R, Marrannes R, Janssen PA. Extracellular ions during veratridine-induced neurotoxicity in hippocampal slices: neuroprotective effects of flunarizine and tetrodotoxin. Brain Res 1990; 528:212-22. [PMID: 2271923 DOI: 10.1016/0006-8993(90)91660-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Veratridine, by blocking Na+ channel inactivation and shifting activation to more negative membrane potentials, causes Na(+)-influx and a persistent tendency for depolarization. Veratridine is neurotoxic to cultured neurones, and this neurotoxicity can be blocked by the class IV calcium antagonist, flunarizine. We were interested to know whether similar effects could be found in a functional differentiated tissue containing adult neurones and glial cells. We examined this in hippocampal slices using extracellular potential recordings and ion-selective microelectrodes sensitive to [Na+]o, [Ca2+]o and [K+]o. Veratridine blocked synaptic transmission in CA1, and induced several episodes of spreading depression (SD). This was followed by a long-lasting increase in [K+]o and a continuous decrease in [Ca+]o. Following veratridine exposure to hypoxia only revealed a small negative DC shift and small shifts in extracellular ions; indicating that the cells had lost the ability to maintain ion homeostasis before the hypoxia, and that veratridine had been neurotoxic. In hippocampal slices obtained from guinea pigs which had been pretreated with 40 mg/kg x 2 flunarizine orally the time before the first SD induced by veratridine was doubled. Although the ion shifts during the first SD were similar to controls, flunarizine reduced the time of recovery of [Ca2+]o, [K+]o and DC potential. The increase in [K+]o baseline and the massive decrease in [Ca2+]o baseline seen following the SDs in the solvent group were smaller in the flunarizine-treated slices. During the subsequent hypoxic period the negative DC shift was 8x larger in the flunarizine group, and the shifts in [K+]o, [Na+]o and [Ca2+]o were bigger. Tetrodotoxin also delayed the first SD during veratridine and increased the size of the DC shift during the subsequent hypoxic period. Both flunarizine and tetrodotoxin therefore protected adult brain tissue containing glia from the neurotoxicity of veratridine. These findings suggest that persistent Na(+)-influx and the consequent Ca2(+)-influx produce neurotoxicity, and that the ability to attenuate this neurotoxicity may be important in the mechanism of action of cerebroprotective drugs from different pharmacological classes.
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Affiliation(s)
- D Ashton
- Department of Neuropsychopharmacology, Janssen Research Foundation, Beerse, Belgium
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340
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Willems R, Paul A, van der Heide HG, ter Avest AR, Mooi FR. Fimbrial phase variation in Bordetella pertussis: a novel mechanism for transcriptional regulation. EMBO J 1990; 9:2803-9. [DOI: 10.1002/j.1460-2075.1990.tb07468.x] [Citation(s) in RCA: 154] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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341
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Willems R, Paul A, van der Heide HG, ter Avest AR, Mooi FR. Fimbrial phase variation in Bordetella pertussis: a novel mechanism for transcriptional regulation. EMBO J 1990. [PMID: 1975238 PMCID: PMC551991] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Fimbriae belong to a class of extracellular filamentous proteins which are involved in the attachment of bacteria to host tissues. Bordetella pertussis, the etiological agent of whooping cough, produces two serologically distinct fimbriae. We show that, like a number of other B. pertussis virulence genes, transcription of the fimbrial subunit genes (fim) is positively controlled by trans-acting polypeptides encoded by the bvg locus. In addition to this coordinate control, transcription of the fim genes is regulated at an individual level by phase variation. This process is characterized by a switching between a high and low level of expression of a particular fim gene. We have identified a conserved DNA region, located close to the start of the fim genes, which is likely to be involved in both positive regulation by the bvg locus, and phase variation. This promoter region contains a stretch of approximately 15 C residues and it appears that phase transitions occur by small insertions or deletions in this C-rich region. We propose that these mutations affect transcription of the fim genes by varying the distance between the binding site for an activator and the -10 box. The fim promoter shows homology with the pertussis toxin promoter, which is also positively regulated by the bvg locus.
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342
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Schuuring E, van der Leede BJ, Willems R, Daams H, van der Valk M, van de Vijver M, van Leeuwen F, Sonnenberg A, Nusse R. Differentiation-dependent expression of provirus-activated int-1 oncogene in clonal cell lines derived from a mouse mammary tumor. Oncogene 1990; 5:459-65. [PMID: 2326076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The int-1 mammary oncogene is frequently activated by proviral insertion in mouse mammary tumors. To characterize the target cell for the oncogenic action of int-1, we have isolated permanent cell lines with distinct morphologies and differentiation characteristics, starting from a tumor with a rearranged int-1 gene. Polygonal cells had retained many differentiation markers of epithelial cells and produced adenocarcinomas upon transplantation in syngenic mice. Sphere-forming-cuboidal cells are poorly differentiated and produced anaplastic tumors. Cuboidal and elongated cells were negative for epithelial markers. Cuboidal cells were poorly tumorigenic, but elongated cells produced highly malignant sarcoma-like tumors. In all lines, the int-1 gene was identically rearranged due to insertion of proviral DNA of the Mouse Mammary Tumor Virus, but the expression of int-1 varied with the state of differentiation of the cells. Polygonal cells contained relatively high levels of int-1 RNA, which were not influenced by steroid hormones. In the sphere-forming-cuboidal cells, expression of int-1 was low but inducible by dexamethasone. In the cuboidal and elongated cells no expression of int-1 was detectable, showing that the continued expression of int-1 was not required for progression to more malignant cells. By immunoprecipitation, two int-1 protein species, of 42 and 40 kD were identified in polygonal and in sphere-forming-cells but not in the culture media.
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Affiliation(s)
- E Schuuring
- Division of Molecular Biology, Netherlands Cancer Institute (Antoni van Leeuwenhoekhuis), Amsterdam
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343
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Le Guellec D, Frappart L, Willems R. Ultrastructural localization of fibronectin mRNA in chick embryo by in situ hybridization using 35S or biotin labeled cDNA probes. Biol Cell 1990; 70:159-65. [PMID: 2103522 DOI: 10.1016/0248-4900(90)90373-b] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
We have studied the expression of the fibronectin gene in 7 day-old chick embryo (stage 32) by in situ hybridization at the light and electron microscope levels, using a 397 base-pairs chicken cDNA, labeled by radioisotope or biotin-11dUTP. Cryostat sections of whole chick embryos displayed a selective label on the upper layer of the dermis, fibrous sclera and mesenchymal cells but not on cartilagenous sclera cells. These results show that the expression of the fibronectin gene varies in relation to the morphogenetic events. Hybridization at the ultrastructural level on thin sections of sclera embedded in Lowicryl K4M showed a selective labelling on various cell compartments. Biotin-11dUTP and radiolabeled probes were compared. The labeling was found precisely on the membrane of the rough endoplasmic reticulum and on the nuclear envelope. A few silver grains were located on the nucleus and in the perinucleolar region. This study shows that the postembedding in situ hybridization is a powerful procedure to study the expression of the extracellular protein genes and gives further information on the localization of mRNA.
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Affiliation(s)
- D Le Guellec
- Institute de Biologie et Chimie des Protéines, CNRS UPR 412, Université Claude Bernard, Villeurbanne, France
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344
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Ashton D, Willems R, Wauquier A. Selective vulnerability of synaptic transmission in hippocampus to ex-vivo ischemia: effects of extracellular ionic substitution in the postischemic period. Brain Res 1989; 487:402-6. [PMID: 2543484 DOI: 10.1016/0006-8993(89)90850-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
After 10-60 min of normothermic complete ischemia, hippocampal slices were prepared and allowed to recover for 60 min. The presence or absence of an evoked transsynaptic response was measured in CA1, CA3, and dentate gyrus. A selective vulnerability of the field excitatory postsynaptic potential to ischemia was found (CA1 greater than CA3 greater than dentate gyrus). Recovery of synaptic transmission in CA1 and CA3 was significantly improved by decreasing extracellular Ca2+ and increasing Mg2+ after ischemia. Addition of an N-methyl-D-aspartate antagonist further improved functional recovery. Postischemic reduction in extracellular Cl- increased recovery in CA1 and CA3, whilst reduction in Na+ was deleterious.
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Affiliation(s)
- D Ashton
- Department of Neuropsychopharmacology, Janssen Research Foundation, Beerse, Belgium
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345
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Ashton D, Van Reempts J, Haseldonckx M, Willems R. Dorsal-ventral gradient in vulnerability of CA1 hippocampus to ischemia: a combined histological and electrophysiological study. Brain Res 1989; 487:368-72. [PMID: 2731049 DOI: 10.1016/0006-8993(89)90842-1] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Transverse hippocampal slices were prepared after 7 days survival from rats subjected to 8 min of global incomplete ischemia by temporary occlusion of both carotid arteries and hypotension. The slices demonstrated a dorsal-ventral gradient in the amount of ischemic neuronal necrosis in the CA1 region. Histologically ischemic cell change decreased from 90% dorsoseptally to 10% ventrotemporally. Electrophysiological analysis of the number of slices with viable synaptic transmission in CA1 also revealed a septotemporal gradient in susceptibility to ischemia.
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Affiliation(s)
- D Ashton
- Department of Neuropsychopharmacology, Janssen Research Foundation, Beerse, Belgium
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346
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Stroobandt R, Willems R, Depuydt P, Holvoet G, Sinnaeve A. The superfast atrial recharge pulse: a cause of pectoral muscle stimulation in patients equipped with a unipolar DDD pacemaker. Pacing Clin Electrophysiol 1989; 12:451-5. [PMID: 2466271 DOI: 10.1111/j.1540-8159.1989.tb02683.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Pectoral muscle stimulation may cause serious discomfort to patients equipped with a pulse generator. Insulation defects of the lead, connector problems and defective coating of the pacemaker can are common causes of local muscle contractions. This report describes pectoral muscle stimulation caused by the atrial superfast recharge pulse incorporated into the atrial channel of a commercially available unipolar DDD pacemaker. As pectoral muscle stimulation could not be eliminated by reprogramming the pacemaker to a lower atrial output in some patients a redesign of the pacemaker is highly required.
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Affiliation(s)
- R Stroobandt
- Department of Cardiology, St.-Jozef Hospital Oostende, Belgium
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347
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Marrannes R, Willems R, De Prins E, Wauquier A. Evidence for a role of the N-methyl-D-aspartate (NMDA) receptor in cortical spreading depression in the rat. Brain Res 1988; 457:226-40. [PMID: 2851364 DOI: 10.1016/0006-8993(88)90690-7] [Citation(s) in RCA: 254] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The neurotransmitter glutamate activates the N-methyl-D-aspartate (NMDA), quisqualate and kainate receptors. It has been proposed, but also disputed, that local release of glutamate would play a pivotal role in cortical spreading depression (SD). We tested this hypothesis by investigating the influence of NMDA antagonists on SD, using the non-competitive NMDA antagonists ketamine, phencyclidine (PCP) and MK-801 and the competitive NMDA antagonist DL-2-amino-7-phosphonoheptanoate (2-APH), injected intraperitoneally in rats anesthetized with alfentanil. SD was elicited by cathodal DC-stimulation of the frontal cortex. SD propagation was followed using two ion-sensitive microelectrodes placed in the parietal and occipital cortex. The NMDA antagonists increased SD threshold, decreased the propagation velocity and decreased the duration of the accompanying extracellular DC, K+ and Ca2+ changes at the following doses: 40 mg/kg ketamine, 10 mg/kg PCP, 0.63 mg/kg MK-801, 10 and 40 mg/kg 2-APH. With each NMDA antagonist failure of SD propagation between both microelectrodes could be observed. SD elicitation (or propagation) was inhibited completely with 80 mg/kg ketamine, 3.1 mg/kg MK-801 and 160 mg/kg 2-APH. These NMDA antagonists have also anticonvulsant properties. None of these effects on SD were observed with high doses of other anticonvulsants such as 80 mg/kg phenytoin or 40 mg/kg diazepam. These experiments indicate that endogenous release of excitatory amino acids and their action on the NMDA receptor play an important role in the initiation, propagation and duration of SD.
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Affiliation(s)
- R Marrannes
- Department of Neuropharmacology, Janssen Pharmaceutica, Beerse, Belgium
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348
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Abstract
The effects of nine clinically active antiepileptic drugs and the NMDA antagonist 2-amino-7-phosphonoheptanoic acid (2-APH) were examined in three models in the in vitro hippocampal slice. In the "low Mg2+" model, removal of Mg2+ from the perfusion fluid increased excitatory neurotransmission and led to epileptogenic field potentials. In the "low Ca2+" model, decrease of Ca2+ and increase of Mg2+ and K+ in the perfusion fluid induced spontaneous "bursts" in the absence of synaptic transmission. Paired-pulse stimulation was used to estimate the strength of recurrent inhibition in the "inhibition" model. The rank order of the potency of the compounds to antagonize the second epileptogenic population spike in the low Mg2+ model was 2-APH greater than pentobarbital greater than midazolam greater than phenytoin greater than carbamazepine greater than chlordiazepoxide greater than phenobarbital = flurazepam. Ethosuximide and valproate were inactive. In the low Ca2+ model, the rank order of the potency of the drugs to antagonize spontaneous epileptogenic bursts was phenytoin greater than carbamazepine greater than midazolam greater than pentobarbital greater than chlordiazepoxide greater than flurazepam greater than phenobarbital. 2-APH, ethosuximide, and valproate were inactive. Only pentobarbital was active in the inhibition model. These experiments demonstrate the potential of in vitro tests in the hippocampus to reveal profiles of anticonvulsant activity.
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Affiliation(s)
- D Ashton
- Department of Neuropharmacology, Janssen Pharmaceutica, Beerse, Belgium
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349
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Ashton D, Willems R, De Prins E, Wauquier A. Selective inhibition of synaptic versus non-synaptic epileptogenesis by NMDA antagonists in the in vitro hippocampus. Epilepsy Res 1988; 2:219-22. [PMID: 2848699 DOI: 10.1016/0920-1211(88)90059-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Three NMDA antagonists (2-amino-7-phosphonoheptanoic acid (APH), MK-801, and ketamine) were tested for their ability to antagonize epileptogenic responses in a synaptic and a non-synaptic model of epileptogenesis in the CA1 region of the hippocampal slice. IC50 values for antagonism of the second population spike in the 'low Mg2+' synaptic model were MK-801 1.5 x 10(-7) M, APH 7.4 x 10(-7) M, ketamine 7.5 x 10(-7) M. IC50 values for antagonism of the frequency of spontaneous field bursts in the non-synaptic 'low Ca2+' model were MK-801 3.2 x 10(-5) M, ketamine 3.2 x 10(-5) M and APH greater than 10(-4) M. The antiepileptogenic action of NMDA antagonists is therefore more pronounced in the model with an important involvement of the NMDA receptor ionophore.
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Affiliation(s)
- D Ashton
- Department of Neuropharmacology, Janssen Research Foundation, Beerse, Belgium
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350
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Ashton D, De Prins E, Willems R, Van Belle H, Wauquier A. Anticonvulsant action of the nucleoside transport inhibitor, soluflazine, on synaptic and non-synaptic epileptogenesis in the guinea-pig hippocampus. Epilepsy Res 1988; 2:65-71. [PMID: 3197688 DOI: 10.1016/0920-1211(88)90021-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The effects of the nucleoside transport inhibitor, soluflazine, were examined on synaptic and non-synaptic epileptogenesis, and on paired-pulse facilitation and inhibition in the CA1 region of the guinea-pig hippocampal slice. In the model of synaptic epileptogenesis, excitation was enhanced by omitting Mg2+ from the artificial cerebrospinal fluid (ACSF). This procedure induced a second epileptogenic population spike (PS) after orthodromic stimulation, which was inhibited by soluflazine (IC50 value 1.2 x 10(-6) M). In the non-synaptic model of epileptogenesis spontaneous depolarizing 'burst' discharges were induced in CA1 by lowering the concentration of Ca2+ and increasing the concentration of K+ and Mg2+. The IC50 value of soluflazine was 6.0 x 10(-7) M for antagonizing 'burst' frequency and 7.5 x 10(-6) M for 'burst' amplitude, indicating a preferential effect on 'burst' initiation. After paired orthodromic stimuli to stratum radiatum, the amount of synaptic facilitation of PS amplitude was significantly increased by soluflazine. This was mainly due to a decrease in the size of the PS induced by the conditioning pulse. The amount of PS inhibition after antidromic/orthodromic stimulation was not significantly altered by soluflazine. With the exception of the failure of soluflazine to attenuate inhibition, the results obtained with soluflazine resemble those reported for adenosine. This strengthens the hypothesis that soluflazine increases the extracellular concentration of adenosine. Further, the results indicate that centrally active nucleoside transport inhibitors may be a new class of antiepileptic drug.
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Affiliation(s)
- D Ashton
- Department of Neuropharmacology, Janssen Pharmaceutica Research Laboratories, Beerse, Belgium
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