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Biomedical subjects

A Meijer

Publications and source records attributed to A Meijer.

At least 19 recordsLinked to original sources
PubMed1996

Reocclusion: the flip side of coronary thrombolysis.

Since the introduction of thrombolytic therapy for acute myocardial infarction, the incidence of coronary artery reocclusion has been intensively studied. Also, the prediction and diagnosis of reocclusion by angiographic and clinical variables, as well its invasive and pharmacologic prevention, have gained much attention. By angiographic definition, reocclusion requires three angiographic observations: one with an occluded artery, one with a reperfused artery and a third for the assessment of subsequent occlusion (true reocclusion). Since the introduction of early intravenous reperfusion therapy, most studies use only two angiograms: one with a patent and one with a nonpatent infarct-related artery. A search for all published reocclusion studies revealed 61 studies (6,061 patients) with at least two angiograms. The median time interval between the first angiogram after thrombolysis and the second was 16 days (range 0.1 to 365). Reocclusion was observed in 666 (11%) of 6,061 cases. Interestingly, the 28 true reocclusion studies showed an incidence of reocclusion of 16 +/- 10% (mean +/- SD), and the 33 studies with only two angiograms 10 +/- 8% (p=0.04), suggesting that proven initial occlusion of the infarct-related artery is a risk factor for reocclusion after successful thrombolysis. The other predictors for reocclusion are probably severity of residual stenosis of the infarct-related artery after thrombolysis and perhaps the flow state after lysis. Reocclusion is most frequently seen in the early weeks after thrombolysis. The clinical course in patients with reocclusion is more complicated than in those without this complication. Left ventricular contractile recovery after thrombolysis is hampered by reocclusion. Routine invasive strategies have not been proven effective against reocclusion. In the prevention of reocclusion, both antiplatelet and antithrombin strategies have been tested, including hirudin and hirulog, but the safety of these agents in thrombolysis is still questionable. Thus, reocclusion after thrombolysis is an early phenomenon and is more frequent after proven initial occlusion of the infarct-related artery. Reocclusion can be predicted by angiography after thrombolysis. Because reocclusion is detrimental, strategies to prevent it should be developed and carried out after thrombolytic therapy for acute myocardial infarction as soon as they are deemed safe.

Antithrombins↗
PubMed1995

Adverse long-term effects of reocclusion after coronary thrombolysis.

OBJECTIVES: This study sought to assess the long-term clinical consequences of reocclusion after coronary thrombolysis. BACKGROUND: After acute myocardial infarction successfully treated with thrombolysis, reocclusion occurs in approximately 30% of patients and leads to poorer in-hospital outcome. However, the long-term effects of reocclusion are unknown. METHODS: Three hundred patients with no history of coronary surgery and with a patent infarct-related artery at coronary angiography within 48 h after thrombolysis were enrolled in the Antithrombotics in the Prevention of Reocclusion in Coronary Thrombolysis (APRICOT) trial. At a mean (+/- SD) of 77 +/- 23 days after thrombolysis, 248 patients (87%) underwent follow-up angiography. Reocclusion was observed in 71 (29%) of 248 patients. To compare outcome between 71 patients with and 177 without reocclusion an analysis of event-free survival, defined as a clinical course without death, reinfarction and revascularization, was performed. RESULTS: Over a 3-year follow-up period, event-free survival was significantly better in patients without reocclusion: At 1 year it was 63% for patients with and 83% for those without reocclusion (p < 0.001). In the first year, two or more cardiac-related events occurred in 24% of patients with and 6% of those without reocclusion (p < 0.001). Patients with reocclusion had a markedly higher reinfarction and revascularization rate. At 1 year the reinfarction rate was 23% for patients with and 5% for those without reocclusion (p < 0.001). CONCLUSIONS: This analysis shows the adverse influence of reocclusion on long-term clinical outcome in relation to reinfarction and need for revascularization. To further optimize prognosis after thrombolysis, prevention of reocclusion should become a main priority. Future research should focus on the criteria and timing of elective revascularization procedures in the prevention of coronary reocclusion.

Aged↗
PubMed1995

Reflectance pulse oximetry at the forehead improves by pressure on the probe.

In this study, we investigated the possibility of improving reflectance (back-scatter) pulse oximetry measurements by pressure applied to the probe. Optimal signal detection, with the probe applied to an easily accessible location, is important to prevent erroneous oxygen saturation readouts. At the foreheads of 10 healthy adult volunteers, the effects of pressure applied onto the reflectance pulse oximeter probe were studied. Distances between the LEDs (660 nm and 940 nm) and the three photodiodes in the sensor were 4 mm, 7 mm, and 10 mm. For each detector, recordings were evaluated regarding red-to-infrared (R/IR) ratios and pulse sizes in relation to the stepwise increased pressure applied to the probe. R/IR variability decreased with applied pressures between 60 and 120 mm Hg. These findings are partly attributed to a corresponding increase in red and infrared pulse sizes at the detectors, which results in an improved signal-to-noise ratio. It is thought that pressure onto the oximeter sensor forces venous blood out of the tissues underneath the sensor. Consequently, the disturbing influence of pulsating and non-pulsating venous blood is reduced. Moreover, the increased difference in vessel diameter between diastole and systole and the corresponding difference in light absorption and an increase in flow velocities, causes an increase in pulse size with increasing pressure on the probe. Pressure applied to the probe may be useful in increasing the accuracy of reflectance pulse oximetry.

Adult↗
PubMed1995

Cure of interfascicular reentrant ventricular tachycardia by ablation of the anterior fascicle of the left bundle branch.

INTRODUCTION: Fascicular reentrant ventricular tachycardia (VT) using the anterior fascicle of the left bundle anterogradely is rare and may produce identical QRS morphology during sinus rhythm and VT. Catheter ablation of this type of VT has not been described in detail. METHODS AND RESULTS: In a postinfarct patient with dilated left ventricle and recurrent VT (showing a QRS configuration of right bundle branch, left posterior fascicular block), endocardial recordings from the His-Purkinje system showed that VT was due to interfascicular reentry. Induction of VT occurred after progressive retrograde conduction delay on increasing the prematurity of the extrastimulus. Anterograde conduction occurred exclusively over the left anterior fascicle, which caused identical QRS morphology during sinus rhythm and VT. During VT, the left posterior fascicle was used retrogradely. The usual target for bundle branch reentry ablation, the right bundle, did not participate in the reentrant circuit. While performing left ventricular endocardial mapping, VT was interrupted when positioning the catheter on the left anterior fascicle, and "reversed" nonsustained bundle branch reentry occurred with anterograde conduction over the posterior fascicle and retrograde conduction over the anterior fascicle. Ablation of conduction in the anterior fascicle led to cure of the VT. CONCLUSION: Interfascicular reentrant VT with right bundle branch block, right-axis QRS configuration can be cured by catheter ablation of anterior fascicle conduction.

Aged↗
PubMed1994

Activation of human monocytes via a non-neurokinin substance P receptor that is coupled to Gi protein, calcium, phospholipase D, MAP kinase, and IL-6 production.

Substance P (SP) is a tachykinin involved in the regulation of inflammatory processes. Tachykinins bind to three subtypes of neurokinin (NK) receptors. However, recently we demonstrated that monocytes express a SP binding site that is not one of the known NK receptors. Activation of this SP receptor leads to the stimulation of MAP kinase in monocytes. In the present paper we show that this novel SP binding site is coupled to a GTP binding protein of the Gi alpha 1/2 subclass. Triggering of the SP receptor leads to a rapid rise in cytosolic calcium. In a more sustained way, SP stimulates phospholipase D (PLD) activity in human monocytes. The effects of SP on calcium, PLD, and MAP kinase activity can be blocked by pretreatment of the cells with pertussis toxin, which is in agreement with receptor coupling to Gi. At a functional level, stimulation of the non-NK SP receptor on monocytes results in the induction of IL-6 production. We show here that the order of potency for activation of monocytes by various ligands is directly related to the Ki for displacement of labeled SP by these ligands. Therefore, our data strongly suggest that the effects of SP are mediated via the novel SP receptor we recently described.

Calcium↗
PubMed1994

Coronavirus M proteins accumulate in the Golgi complex beyond the site of virion budding.

The prevailing hypothesis is that the intracellular site of budding of coronaviruses is determined by the localization of its membrane protein M (previously called E1). We tested this by analyzing the site of budding of four different coronaviruses in relation to the intracellular localization of their M proteins. Mouse hepatitis virus (MHV) and infectious bronchitis virus (IBV) grown in Sac(-) cells, and feline infectious peritonitis virus (FIPV) and transmissible gastroenteritis virus (TGEV) grown in CrFK cells, all budded exclusively into smooth-walled, tubulovesicular membranes located intermediately between the rough endoplasmic reticulum and Golgi complex, identical to the so-called budding compartment previously identified for MHV. Indirect immunofluorescence staining of the infected cells showed that all four M proteins accumulated in a perinuclear region. Immunogold microscopy localized MHV M and IBV M in the budding compartment; in addition, a dense labeling in the Golgi complex occurred, MHV M predominantly in trans-Golgi cisternae and trans-Golgi reticulum and IBV M mainly in the cis and medial Golgi cisternae. The corresponding M proteins of the four viruses, when independently expressed in a recombinant vaccinia virus system, also accumulated in the perinuclear area. Quantitative pulse-chase analysis of metabolically labeled cells showed that in each case the majority of the M glycoproteins carried oligosaccharide side chains with Golgi-specific modifications within 4 h after synthesis. Immunoelectron microscopy localized recombinant MHV M and IBV M to the same membranes as the respective proteins in coronavirus-infected cells, with the same cis-trans distribution over the Golgi complex. Our results demonstrate that some of the M proteins of the four viruses are transported beyond the budding compartment and are differentially retained by intrinsic retention signals; in addition to M, other viral and/or cellular factors are probably required to determine the site of budding.

Animals↗
PubMed1994

Left ventricular function at 3 months after successful thrombolysis. Impact of reocclusion without reinfarction on ejection fraction, regional function, and remodeling.

BACKGROUND: After successful thrombolysis for acute myocardial infarction, reocclusion is observed in about 30% of patients after 3 months and usually occurs without reinfarction. We studied the impact of reocclusion without reinfarction on global and regional left ventricular function and on remodeling during that period. METHODS AND RESULTS: The patients for this analysis constituted a subset of those enrolled in the APRICOT-trial, which was designed to study the efficacy of antithrombotics on the prevention of reocclusion. Patients were selected who had a left anterior descending- or right coronary artery-related myocardial infarction, had an angiographically patent infarct-related vessel when studied < 48 hours after intravenous thrombolysis, and underwent repeat cardiac catheterization at 3 months. Paired contrast ventriculograms of quality sufficient to analyze regional wall motion, global ejection fraction, and ventricular volumes were analyzed in 129 patients. Enzymatic infarct size and baseline left ventricular function as well as other baseline characteristics were similar in patients with (n = 34) and without (n = 95) reocclusion. Ejection fraction improved in anterior infarction without reocclusion from 47 +/- 10% to 54 +/- 13% (P = .0001) but not with reocclusion (baseline, 48 +/- 13%; 3 months, 48 +/- 16%). No improvement was seen in inferior infarction with or without reocclusion. Persistent patency allowed preservation of end-systolic volume index (ESVI) at 3 months (37 +/- 14 mL/m2) to baseline level (38 +/- 13 mL/m2), with a better chance for improvement of > 10 mL/m2 without reocclusion in those with baseline values > 40 mL/m2. After reocclusion, in contrast, ESVI increased from 37 +/- 14 to 43 +/- 20 mL/m2 (P = .08). Comparable mean changes of ESVI in response to persistent patency or reocclusion were seen in anterior versus inferior infarction. Recovery of infarct zone contractility was impaired by reocclusion, both in terms of abnormality of segment shortening and expressed in the number of segments showing abnormal wall motion. In anterior but not in inferior infarction, infarct zone contractility was better with good collaterals to the reoccluded artery compared with poor collaterals. CONCLUSIONS: After successful thrombolysis for acute myocardial infarction, reocclusion without reinfarction withholds salvaged myocardium from regaining contractility. This has deleterious consequences for regional and global left ventricular function and for remodeling. To further optimize prognosis in patients after thrombolysis, future research should focus on the prevention of reocclusion and should evaluate revascularization therapy in patients with reocclusion.

Collateral Circulation↗
PubMed1993

Aspirin versus coumadin in the prevention of reocclusion and recurrent ischemia after successful thrombolysis: a prospective placebo-controlled angiographic study. Results of the APRICOT Study.

BACKGROUND: Successful coronary thrombolysis involves a risk for reocclusion that cannot be prevented by invasive strategies. Therefore, we studied the effects of three antithrombotic regimens on the angiographic and clinical courses after successful thrombolysis. METHODS AND RESULTS: Patients treated with intravenous thrombolytic therapy followed by intravenous heparin were eligible when a patent infarct-related artery was demonstrated at angiography < 48 hours. Three hundred patients were randomized to either 325 mg aspirin daily or placebo with discontinuation of heparin or to Coumadin with continuation of heparin until oral anticoagulation was established (international normalized ratio, 2.8-4.0). After 3 months, in which conservative treatment was intended, vessel patency and ventricular function were reassessed in 248 patients. Reocclusion rates were not significantly different: 25% (23 of 93) with aspirin, 30% (24 of 81) with Coumadin, and 32% (24 of 74) with placebo. Reinfarction was seen in 3% of patients on aspirin, in 8% on Coumadin, and in 11% on placebo (aspirin versus placebo, p < 0.025; other comparison, p = NS). Revascularization rate was 6% with aspirin, 13% with Coumadin, and 16% with placebo (aspirin versus placebo, p < 0.05; other comparisons, p = NS). Mortality was 2% and did not differ between groups. An event-free clinical course was seen in 93% with aspirin, in 82% with Coumadin, and in 76% with placebo (aspirin versus placebo, p < 0.001; aspirin versus Coumadin, p < 0.05). An event-free course without reocclusion was observed in 73% with aspirin, in 63% with Coumadin, and in 59% with placebo (p = NS). An increase of left ventricular ejection fraction was only found in the aspirin group (4.6%, p < 0.001). CONCLUSIONS: At 3 months after successful thrombolysis, reocclusion occurred in about 30% of patients, regardless of the use of antithrombotics. Compared with placebo, aspirin significantly reduces reinfarction rate and revascularization rate, improves event-free survival, and better preserves left ventricular function. The efficacy of Coumadin on these end points appears less than that of aspirin. The still-high reocclusion rate emphasizes the need for better antithrombotic therapy in these patients.

Aged↗
PubMed1992

Identifying patients for rate responsive atrial pacing: a new method for patient selection and pacemaker programming.

In patients with sinus node disease (SND) and chronotropic incompetence, atrial rate adaptive stimulation (AAI,R pacing) is regarded as the most appropriate pacing mode. Since coronary artery disease is the most common etiology in these patients, we evaluated a new technique combining two-dimensional transesophageal echocardiography and atrial transesophageal pacing to detect pacing induced wall motion abnormalities and assess safe upper rate limits. Thirty-five patients were studied: 26 with and 9 without angiographic coronary artery disease. Stable atrial capture was achieved in all patients using 12 +/- 3 msec pulse width and 12 +/- 4 mA current strength. Sensitivity and specificity for the detection of coronary artery disease was highest for transesophageal echocardiography during pacing (sensitivity 81%, specificity 100%). Simultaneous 12-lead ECG during pacing had lower values (sensitivity 57%, specificity 75%). Pacing induced wall motion abnormalities preceded ST segment changes in all patients. Exercise stress testing showed similar values (sensitivity 62%, specificity 89%). It is concluded that simultaneous transesophageal echocardiography and transesophageal pacing is a safe and useful technique in selecting patients for AAI,R pacing and for the detection of safe upper rate limits, particularly when coronary artery disease is suspected.

Algorithms↗
PubMed1989

Prevalence of antibody to current influenza virus strains in adolescents.

During the Spring of 1986, 118 pupils aged 15-18 years were surveyed for the presence of humoral antibodies to five influenza strains. Prevalence of humoral immunity (HI) antibodies and immunity was found to be related to the year of the strain's emergence and to length of circulation time in the community. A high percentage of the adolescents were not immune to one or more of the tested strains. More than 40% of the studied group were not immune to the old A strains A/Philipines 2/82 (H3N2) and A/Chile 1/83 (H1N1), nearly 70% were not immune to the two B strains (B/USSR 100/83 and B/Ann Arbor 1/86), and almost the entire group (96%) was unprotected against the recent strain A/Singapore 6/86. Only one pupil was immune to all five strains; 35.6%, 22.2%, 17.8%, and 9.2% were immune to one, two, three, or four of the strains, respectively; and 14.4% were not immune to even one strain.

Adolescent↗
PubMed1989

Emergency room infusion of intravenous streptokinase in acute myocardial infarction: feasibility, safety, and hemodynamic consequences.

Between September 1, 1986, and December 31, 1987, sixty-four consecutive patients younger than 70 years, with early (less than 4 hours) symptoms and signs of myocardial infarction, were treated with 1.5 million units streptokinase intravenously in the emergency room (ER group) before admission to the coronary care unit. Data from these patients were compared in retrospect to those of 66 consecutive patients with myocardial infarction who were treated with intravenous streptokinase in the coronary care unit (CCU group) before September 1, 1986. Time between first symptoms and initiation of fibrinolytic therapy was significantly shorter in the ER group: 114 +/- 53 minutes vs 150 +/- 56 minutes in the CCU group (p less than 0.001). The incidence of in-hospital complications was similar in both groups. However, left ventricular stroke work index during the stay in the coronary care unit was 50 +/- 19 gm/m2 in the ER group vs 42 +/- 14 in the CCU group (p = 0.02). Also the echocardiographic left ventricular wall motion score at 48 hours after admission tended to be better in the ER group: 6.7 +/- 4.0 compared to that in the CCU group (7.6 +/- 4.5; p = 0.29). In conclusion, infusion of intravenous streptokinase in the emergency room is feasible and safe and results in a significant time gain leading to a better hemodynamic profile. Within the hospital the emergency room is the ideal place for intravenous fibrinolytic therapy in eligible patients with acute myocardial infarction.

Adult↗
PubMed1989

The association of physical illness and environmental factors with mood disorder in adolescents.

This study on adolescents focuses on the association of psychological distress and mood disorder with illness and environmental sources of distress. The subjects were 505 high school students--346 boys and 159 girls. Psychological distress and mood disorder were measured with the Brief Symptom Inventory of Derogatis. To a significant degree, both were predicted by nonfebrile physical illness and life events. However, illness had a significantly stronger effect on girls than boys. In both sexes, feelings about school and home were significant predictors of psychological distress and mood disorder, but feelings about school were much less positive than feelings about home.

Adolescent↗
PubMed1988

Post-influenzal psychiatric disorder in adolescents.

The association between influenza and psychiatric disorder in adolescents was studied at a time when both were highly prevalent concurrently. First 505 secondary school pupils aged 15-18 completed questionnaires, including a symptom inventory derived from the SCL-90-R. Subsequently, 113 blood samples were examined for influenza antibody titers of five virus strains. Statistical analysis showed that adolescents who had been ill with influenza in the previous six months had significantly more psychiatric disorder than those who had not been ill with influenza in that period.

Adolescent↗
PubMed1985

Learning achievement and behavior at school of anemic and non-anemic infants.

In a prospective study the learning achievement and behaviour of second grade children who were anemic in infancy (n = 20) was compared with that of non-anemic children (n = 55). All children received preventive care and were under surveillance from birth at the Community Health and Research Center of Hadassah in Jerusalem. The anemic children had a hemoglobin level of less than 10.5 g/dl whereas the comparison group had more than 11.5 g/dl at 9 months of age. The learning achievement score was significantly lower in the anemic group 9.3 S.D. 3.8, than in the non-anemic group 11.5 S.D. 2.9 (P = 0.009). The positive task orientation was also significantly lower in the anemic group, though on additional behavior scores no differences were found. Differences remained significant even after controlling for maternal education and sex of child in a multivariate analysis. It is possible that an iron deficiency state which persists during the critical period of brain development in infancy has long-lasting effects on cognitive functioning. Prevention of iron deficiency may contribute to promotion of child development and better achievement.

Achievement↗
PubMed1985

Child psychiatric sequelae of maternal war stress.

Two cohorts of boys were examined while attending a well-baby clinic and reexamined at the end of the first grade of elementary school. One cohort (n = 57) consisted of boys born in the year of the Six-Day War in 1967. The other cohort was born 2 years later (n = 63). Data on socio-demographic background, early development, behavior at school and at home were obtained from the mothers and the teachers. Statistical analysis showed that the "war children" had significant developmental delays and regressive, non-affiliative and dissocial behavior. The children, who were in their first half year of life at the time of the war, were much more disturbed than those of whom the mothers were pregnant at the time of the war. The findings suggest that a disturbed mother-child relationship existed in the former group.

Child↗