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Biomedical subjects

A E Becker

Publications and source records attributed to A E Becker.

At least 91 records · Page 5Linked to original sources
PubMed1995

Smooth muscle cell de-differentiation is a fundamental change preceding wound healing after percutaneous transluminal coronary angioplasty in humans.

BACKGROUND: Wound healing at the site of medial injury after percutaneous transluminal coronary angioplasty (PTCA) is dominated by smooth muscle cells. This reaction may also cause restenosis. Division and migration of smooth muscle cells relate closely to their cytoskeletal features, as shown experimentally, but in humans little information is available regarding smooth muscle cell activity in post-angioplasty coronary arteries. MATERIALS AND METHODS: This study is based on eight dilated coronary arteries obtained at autopsy from six patients who died within 4 months of an initially successful PTCA. In each patient, a single PTCA had been performed and the target site was identified, sectioned serially, and studied with conventional and immunohistochemical techniques. RESULTS: All target sites showed laceration extending into the media. Two days after PTCA the site of injury was covered by a fibrin-platelet thrombus. The smooth muscle cells of the pre-existent media, immediately adjacent to the site of injury, showed loss of staining for both muscle actin and smooth muscle cell actin, using the antibodies HHF-35 (an anti-muscle actin marker) and CGA-7 (an anti-smooth muscle cell actin marker), respectively. Five days after PTCA, this area had expanded; a distinct influx of macrophages was apparent. From 12 days onwards, the staining density with HHF-35 in the pre-existent media increased and was almost restored to normal at 20 days, but staining with CGA-7 was retarded until approximately 4 months after PTCA. In the repair tissue, spindle-shaped cells were first seen 5 days after PTCA. These cells stained positive with vimentin but did not stain with either actin marker. Macrophages were present at this stage. At 12 days after PTCA, some spindle-shaped cells stained positive with HHF-35, but all were negative with CGA-7. At 16 days, the staining density with HHF-35 had increased, but CGA-7 was still negative. At 20 days, the maximal staining density with HHF-35 was obtained. The vast majority of spindle-shaped cells also stained positive with CGA-7 4 months after PTCA. Endothelial cells on the luminal surface were first identified 4 months after PTCA. CONCLUSION: The observations provide support that cytoskeletal changes observed experimentally also play a role in human coronary arteries after PTCA. De-differentiation of smooth muscle cells of the pre-existent media, preceding a noticeable cellular response, appears to be a fundamental process.

Aged↗
PubMed1994

Quantification in immunohistochemistry: the measurement of the ratios of collagen types I and II.

Quantitative techniques in immunohistochemistry are needed, but they are rarely applied because of doubtful reproducibility. We have developed a method for the detection of collagen types I and III in situ. The method applied was a two-step immuno-alkaline phosphatase technique with visualization of the end-product with Fast Red. The staining intensity was measured with a microdensitometer and the results expressed as ratios. The method yielded results that were unaffected by variations in tissue section thickness but which were proportionally related to time and antigen concentrations. Leiomyoma tissue, with a ratio of collagen types I and III of approximately 1.0, was used to establish the appropriate dilutions of the antibodies, thus assuring identical optical densities. By having the leiomyoma tissue sections incubated together with the heart tissue specimens, leiomyoma tissue was also helpful in correcting deviations from the 1.0 ratio. Accurate measurements of collagen type I/III ratios in normal human heart specimens were obtained with the present quantitative immunohistochemical technique.

Adolescent↗
PubMed1994

The neonatal heart has a relatively high content of total collagen and type I collagen, a condition that may explain the less compliant state.

OBJECTIVES: This study evaluated the extent of the collagen network in neonatal heart muscle and whether the type I/type III collagen ratio is the same as in the adult heart. BACKGROUND: The functional integrity and the stress-strain relation of heart muscle depends largely on the extracellular collagen matrix. The question therefore arises whether the altered compliance of the neonatal heart could relate to the developmental state of collagen and, in particular, the distribution of types I and III collagen. Type I collagen mainly provides rigidity and type III collagen elasticity. METHODS: Specimens from the left lateral wall of the left ventricle of human hearts (immature to full term, n = 23; 3 weeks to 12 years, n = 17) were used to determine the total collagen amount, using the hydroxyproline assay. Similar left ventricular specimens of human hearts (fetal to mature, n = 20; 2 months to 1.5 years, n = 6) were fixed in formalin, paraffin embedded and stained with Sirius red F3BA for total collagen. The ratio of total collagen to total protein was quantified spectrophotometrically. Frozen sections of left ventricular myocardium (immature to mature, n = 17; 4 months to 12 years, n = 10) were stained with antibodies raised against types I and III collagen. Antibody titration was done on human leiomyoma tissue with a known type I/type III collagen ratio. The endomysial collagen types were quantified using a spectrophotometer and expressed as a ratio. Adult human myocardium (n = 10) was used as reference. RESULTS: The study showed that the total amount of collagen increases with age. However, the ratio of total collagen to total protein and the ratio of type I to type III collagen were very high in hearts of the very young. During development, a gradual decrease occurred, with the total collagen/total protein ratio reaching normal levels at approximately 5 months after birth and the type I/type III collagen ratio stabilizing at a much later age. CONCLUSIONS: These findings suggest that the relative high content of collagen, related to the myocytes, and the high ratio of type I to type III collagen provide the substrate for a rigid, less compliant heart in neonates.

Cadaver↗
PubMed1994

The congenital bicuspid aortic valve with post-inflammatory disease--a neglected pathological diagnosis of clinical relevance.

It is unusual to find surgically excised congenital bicuspid aortic valves with post-inflammatory disease. We have analysed retrospectively all surgically excised aortic valves over a 6-year period for this particular diseased state in relation to relevant clinical data. There were 181 congenital bicuspid aortic valves, and the characteristic gross pathology of the tricuspid aortic valve with post-inflammatory disease served as reference. Twelve of the 181 congenital bicuspid aortic valves were identified as post-inflammatory (6.6%); one with clinically established rheumatic disease. The mean age at operation of these 12 patients was significantly lower compared to 'other' aortic valves. The study indicates that post-inflammatory involvement of a congenital bicuspid aortic valve can be identified, which is of clinical relevance since these patients have a significantly younger age at operation.

Adult↗
PubMed1994

Abnormal automaticity as mechanism of atrial tachycardia in the human heart--electrophysiologic and histologic correlation: a case report.

INTRODUCTION: A 32-year-old woman was operated upon because of drug refractory atrial tachycardia. METHODS AND RESULTS: Electrophysiologic study was performed prior to operation. During surgery, epicardial mapping of the electrical activity of the left atrium was performed. The left atrial appendage was resected and studied in a tissue bath. Thereafter, histologic examination was performed. Polarity of the P wave in the surface ECG suggested that the tachycardia originated high in the left atrium. Epicardial mapping disclosed earliest activation in the apex of the left atrial appendage. Intracellular recordings from surgical specimen made at the site of origin, which was marked during surgery, revealed cells with phase 4 depolarization at cycle lengths ranging from 360 to 540 msec. Exit block prevented spread of activation from the spontaneously firing cells to surrounding tissue. Histology showed that spontaneous activity arose in an area with abnormal cells--characterized by an amorphous, pale eosinophilic staining cytoplasm and absence of nuclei--surrounded by normal myocytes. CONCLUSION: The observations indicate that the mechanism of the atrial tachycardia was based on abnormal automaticity in an area consisting of a conglomeration of normal and abnormal myocytes.

Adult↗
PubMed1994

Site of intimal rupture or erosion of thrombosed coronary atherosclerotic plaques is characterized by an inflammatory process irrespective of the dominant plaque morphology.

BACKGROUND: The study was designed to verify the concept of plaques "at risk" and whether inflammation could play a role in plaque rupture and thrombosis. METHODS AND RESULTS: In 20 patients who had died of acute myocardial infarction, the thrombosed coronary artery was identified and the site of plaque rupture was traced in serial sections. The cellular characteristics of the fibrous cap at the immediate site of rupture were analyzed and compared with the adjacent cap tissue by use of monoclonal antibodies reactive with macrophages, T lymphocytes, and smooth muscle cells. A deep intimal rupture, extending into the lipid core, was encountered in 12 plaques, whereas 8 had superficial erosions only. Ten atherosclerotic plaques had a distinctly attenuated fibrous cap covering a large atheroma, 7 showed a thick fibrocellular cap overlying a lipid pool, and 3 showed a fibrocellular lesion without a clear lipid core. Macrophages, and to a lesser extent T lymphocytes, were the dominant cells at the immediate site of either rupture or superficial erosion in each instance. These sites, moreover, were always characterized by abundant expression of HLA-DR antigens on both inflammatory cells and adjacent smooth muscle cells, suggesting an active inflammatory reaction. In terms of overall cellular composition of the ruptured plaques, the dominant cell types were macrophages and T cells in 11, smooth muscle cells in 3, and mixtures of both in 6. CONCLUSIONS: The underlying atherosclerotic plaque morphology in complicated coronary artery lesions causing acute myocardial infarction is heterogeneous with respect to both plaque architecture and cellular composition. However, the immediate site of plaque rupture or erosion is always marked by an inflammatory process. This suggests that inflammation plays a role in destabilizing the fibrous cap tissue and, thus, in enhancing the risk of coronary thrombosis.

Coronary Artery Disease↗
PubMed1994

Origin and significance of double potentials near the atrioventricular node. Correlation of extracellular potentials, intracellular potentials, and histology.

BACKGROUND: Atrioventricular junctional (AV nodal) reentrant tachycardia can be cured by catheter ablation of the slow pathway, which is part of the reentrant circuit. Previous work has suggested that extracellular double potentials may help identify the site of the slow pathway, but the origin and significance of these potentials are controversial. The aim of this study was to identify the source of these potentials. METHODS AND RESULTS: Studies were performed in isolated, blood-perfused porcine (n = 8) and canine (n = 4) hearts. Several methods were used to identify the origin of potentials: microelectrode recording, extracellular mapping, pacing from multiple sites, and light microscopy. Two types of double potentials, similar to those found in humans, were found in all hearts. LH potentials consisted of a low-frequency deflection followed by a high-frequency deflection during sinus rhythm or anterior septal pacing. HL potentials consisted of a high-frequency deflection followed by a low-frequency deflection. LH potentials were found close to the coronary sinus orifice. They were caused by asynchronous activation of the sinus septum and the region between the coronary sinus orifice and tricuspid annulus. HL double potentials were found along the tricuspid annulus. They were caused by asynchronous activation of two cell layers. The high-frequency component was caused by depolarization of atrial-type cells in the deep subendocardial layer. The low-frequency component was caused by depolarization of cells with nodal characteristics close to the endocardium. These cells were present around the entire tricuspid annulus, were not part of the compact AV node, and could be dissociated from the bulk of the atria by rapid atrial pacing. CONCLUSIONS: LH potentials are caused by asynchronous activation of muscle bundles above and below the coronary sinus orifice. Their proximity to the site of the slow pathway is probably serendipity. HL double potentials are caused by asynchronous activation of atrial cells and a band of nodal-type cells close to the tricuspid annulus. The band of nodal-type cells is not part of the compact AV node and may represent the substrate of the slow AV nodal pathway.

Action Potentials↗
PubMed1994

Double epi-illumination microscopy with separate visualization of two antigens: a combination of epi-polarization for immunogold-silver staining and epi-fluorescence for alkaline phosphatase staining.

We present a method for an epi-illumination immunohistochemical double staining approach. The method combines the use of an immuno-alkaline phosphatase technique and the immunogold-silver technique, visualized with epifluorescence and epi-polarization illumination, respectively. Out of six tested alkaline phosphatase activity-revealing methods, only the reaction product obtained with the Becton Dickinson CAS Red kit showed an intense red fluorescence with a rhodamine filter set and no signal with epi-polarization illumination. The silver precipitate did not exhibit any signal with the rhodamine filter set. This allows separate observation and photographic recording of two antigens in one tissue section, an objective that cannot be achieved with conventional immunoenzyme double staining methods. The double epi-illumination approach presented is compatible with different immunoenzyme double staining protocols.

Alkaline Phosphatase↗
PubMed1994

Fibrous and lipid-rich atherosclerotic plaques are part of interchangeable morphologies related to inflammation: a concept.

BACKGROUND: The morphology of advanced atherosclerotic plaques varies from solid fibrous lesions, considered essentially stable, to lipid-rich lesions with large atheromas prone to rupture. The latter situation is often associated with large amounts of foam cells. An in-situ inflammatory process influenced by activated T cells and macrophages can be demonstrated in atherosclerotic plaques; however, the relationship between the inflammation and clinically relevant morphological types has not yet been investigated. A study of plaque morphology, focusing on the relationship between inflammatory cells, smooth muscle cells, and the collagen matrix, on the one hand, and the 'classic' plaque morphologies (fibrous versus lipid-rich), on the other, may shed light on this concept. MATERIALS AND METHODS: Immunocytochemical techniques were used in combination with connective tissue stains to study the topographic distribution of smooth muscle cells, collagen, and inflammatory cells in different morphologic types of advanced atherosclerotic plaques in aortic and carotid arteries obtained at autopsy. RESULTS: Lesions with an inconspicuous lipid core were defined as fibrous (n = 7). They contained a dense collagen matrix and the dominant cell type was the smooth muscle cell; lymphocytes and macrophages were sparse. Lesions with a large lipid core were defined as lipid-rich (n = 13). They contained a thin fibrous cap with a loosely arranged matrix dominated by macrophages and T cells. Most lesions (n = 21), however, had a morphology that ranged between fibrous and lipid-rich. The cellular components consisted either of mixed smooth muscle and inflammatory cells or of local distinct zones of inflammatory cells within a fibrous cap otherwise dominated by smooth muscle cells and collagen. Thus, zones of severe inflammation were invariably associated with dissolution of the connective tissue matrix and abundant human leukocyte antigen-DR expression on inflammatory cells and the remaining smooth muscle cells. CONCLUSION: Our observations support the concept that inflammatory mechanisms modulate plaque morphology, by promoting either synthesis or lysis of the fibrous cap. Our hypothesis is that fibrous and atheromatous lesions are essentially interchangeable.

Aortic Diseases↗
PubMed1994

Disease of the left ventricle in pulmonary atresia with intact ventricular septum. The limiting factor for long-lasting successful surgical intervention?

Eight hearts with pulmonary atresia with intact ventricular septum were studied grossly and microscopically. The right ventricle was composed of inlet, infundibular, and trabecular portions in two hearts, without trabecular portions in three hearts, and consisted of an inlet part only in another three hearts. Pulmonary atresia was classified as membranous in two hearts; the other six hearts had muscular atresia. The left ventricle showed a range of abnormalities, albeit mostly discrete. A mitral valve with short tendinous chords was present in four hearts; one of these had a cleft mitral valve. All hearts (except the heart of a 1-day-old neonate) had a prominent subaortic septal bulge. All hearts had left ventricular hypertrophy, which exceeded twice the standard deviation of normal in two patients. None of the hearts had histologic features of hypertrophic cardiomyopathy. The density of intramyocardial coronary arteries was normal in each patient, but medial thickening (20 to 100 microns diameter arteries) had occurred in four patients. Signs of acute myocardial ischemia (hydropic cell swelling) were present in all; one heart (the oldest case of 6 months) contained areas of replacement fibrosis and calcifications indicative of previous infarction. Quantification of the volume density of endomysial (interfiber) collagen (Picrosirius red microspectrophotometry) showed high levels in all, within the range of normal in five patients, but exceeding twice the standard deviation of normal in three patients. In all cases the values obtained in the subendocardial layers were higher than those obtained subepicardially. The observations show that the left ventricle in hearts with pulmonary atresia with intact ventricular septum contains abnormalities that may render the left ventricle less capable to cope with a volume load. The high values of endomysial (interfiber) collagen suggest chronic ischemia in relation to left ventricular hypertrophy as the main mechanism involved. Therefore, as a late consequence, the left ventricle could be the limiting factor for long-lasting successful surgical intervention.

Coronary Vessels↗
PubMed1993

Endothelial cell marker PAL-E reactivity in brain tumor, developing brain, and brain disease.

BACKGROUND: The endothelial cell marker PAL-E is not reactive to vessels in the normal brain. The present study concerns the PAL-E reactivity in brain tumors in contrast to normal brain and nonneoplastic brain disease. METHODS: A total of 122 specimens were examined: brain tumors (n = 94), nonneoplastic brain disease (n = 19), normal brain (n = 8), and fetal brain (n = 1). Standard immunohistochemical procedures using a panel of endothelial cell markers were applied to detect vessels reactive to PAL-E. RESULTS: PAL-E reactivity to endothelial cells was found in all cases of glioblastoma multiforme, in 75% of the cases of anaplastic astrocytoma, and in 46% of the cases of astrocytoma. Furthermore, PAL-E reactivity was present in diseases with a developmental etiology, such as primitive tumors and congenital vascular malformations. The developing human brain (6-weeks' gestation age) and special sites of the mature brain, sites without blood-brain barrier, showed a strong reactivity, which indicates a relation with the status of blood-brain barrier development. CONCLUSIONS: PAL-E is the only marker out of a panel of endothelial cell markers that shows no reactivity to endothelial cells in the normal brain with an intact blood-brain barrier. In primary and metastatic brain tumors, PAL-E is reactive to endothelial cells, except for 25% of anaplastic astrocytoma and 54% of astrocytoma. PAL-E reactivity in brain tumors most likely is related to angiogenesis and to blood-tumor barrier properties not present in the normal blood-brain barrier.

Antibodies, Monoclonal↗
PubMed1993

Practical suggestions for successful immunoenzyme double-staining experiments.

Many methodologies exist to perform an immunoenzyme double staining. Hence, the practical problem arises as to which of these methods is optimal for one's own experimental design. A process of selection is described which is derived from our own practical experience. First, a general strategy is outlined for the handling of tissue sections to be used for multiple staining methods. Secondly, the selection of an appropriate immunoenzyme double-staining concept is made using a flow chart. Thereafter we give criteria for the definitive selection of an immunoenzyme double-staining protocol based on the characteristics of the tissue or cell type under study. Particular attention is given to the selection of appropriate detection systems, applying enzymes or gold particles, and good contrasting colour combinations. The problems of visualizing co-localization using immunoenzyme double staining are dealt with, and suggestions are made to adapt the method, if necessary, in order to optimize it.

Animals↗
PubMed1993

Valve morphology in complete atrioventricular septal defect: variability relevant to operation.

The remodeling of the atrioventricular valves in patients with complete atrioventricular septal defects is the crucial part of surgical repair. Variability in valve morphology is an important factor. This study evaluates the variability in morphology of the anterior and posterior leaflets in 30 heart specimens. All hearts had an anterior bridging leaflet: Rastelli type A in 12, type B in 2, and type C in 16. The posterior leaflet revealed four morphologic patterns: a right- and left-sided posterior leaflet, both inserting directly onto the crest of the ventricular septum (5 hearts); a common posterior leaflet attached to the septal crest by a membrane (2 hearts); a common posterior leaflet attached to the septal crest by multiple chordae (13 hearts); and a virtually free-floating posterior leaflet (11 hearts). The categorization is surgically relevant in making a distinction between hearts with and without an interventricular communication underneath the posterior leaflet. Surgically relevant variations occurred also in arrangement and positioning of chordae originating from the right septal side. There was no relationship between the Rastelli classification of the anterior leaflet and that of the posterior leaflet. The variability in morphology of the posterior leaflet and its attachments to the ventricular septum appear equally crucial for successful repair as that of the anterior leaflet.

Chordae Tendineae↗
PubMed1993

Medial thinning and atherosclerosis--evidence for involvement of a local inflammatory effect.

Medial attenuation in relation to atherosclerotic plaques is poorly understood. We investigated the potential role of a local inflammatory response. Segments of carotid artery and descending aorta were studied. The samples were grossly normal (n = 10), presented circumscribed atherosclerotic plaques (n = 19) or confluent atherosclerotic lesions (n = 8). Tissues were fixed in formalin or snap frozen in liquid nitrogen. Sections were stained with conventional staining methods and immunohistochemically (smooth muscle cells, macrophages, and T and B lymphocytes). Medial thickness was measured with an ocular micrometer; inflammatory infiltrates and medial vascularization were assessed semiquantitatively. Increasing severity of intimal lesions was accompanied by a significant increase in medial inflammation and vascularization and by a significant decrease in medial thickness. The inflammatory infiltrates in the media consisted of macrophages and T lymphocytes, localized predominantly around vasa vasorum. In advanced atherosclerosis they spread more diffusely. Inflammatory cells of the intimal atheroma also penetrated the media. At sites of inflammation the media contained HLA-DR positive smooth muscle cells with loss of collagen. The media in confluent atherosclerosis was almost devoid of smooth muscle cells, with loss of collagen and focal fibrosis. We postulate that the inflammatory reaction in the media relates to atherosclerosis, has a remodelling effect on medial tissues and may cause medial attenuation.

Aged↗