Manometrisches Röntgenstrahlen-Aktinometer und über die Wirkung der Röntgenstrahlen auf die Gärung von Krebszellen

Die anaerobe Gärung von Asciteskrebs-Zellen, suspendiert in Ringerlösung in geringer Zelldichte, wird durch Röntgenstrahlen-Dosen von einigen 1000 r um 50% gehemmt. Mit Hilfe dieses „Gärungstestes“ haben wir gefunden, daß die Strahlenwirkung durch das Wasserstoffperoxyd ersetzt werden kann, das die Strahlen in der Zellsuspension erzeugen. — Ein manometrisches Röntgenstrahlen-Aktinometer wurde für diese Versuche entwickelt.

Notizen: Weiterentwicklung der manometrischen Methoden

Die Blausäure wird in den Manometriegefäβen nach beendeter Gasdurchleitung und nach dem Schließen der Hähne aus Quecksilbercyanid entwickelt.

ᴅ-(—)-Milchsäure in Chlorella

Die Milchsäuregärung der Chlorella ist eine ᴅ-Milchsäuregärung. Es folgt daraus, daß die „Milchsäuredehydrase“ der Chlorella im Gegensatz zur Milchsäuredehydrase des Muskels, ein D-Ferment ist. Dabei ist es nicht die Konfiguration des Pyridinnucleotids, sondern des Apoferments, das die Konfiguration der entstehenden Milchsäure bestimmt. Andere D-Fermente haben wir bisher in Chlorella nicht gefunden.

Hemmung der Photosynthese durch Kohlenoxyd und Aufhebung der Kohlenoxydhemmung durch Licht

Die Hemmung der Photosynthese durch Kohlenoxyd und die Aufhebung dieser Hemmung durch Licht werden beschrieben.

Über Gewinnung und Abbau des Cytohämins

Wir beschreiben im Folgenden die Gewinnung und Kristallisation des Cytohämins l aus Pferdeherzen; seine Hydrierung mit Platin und Wasserstoff; seinen Abbau bei der Resorcinschmelze 2 zu Cyto-deutero-porphyrin sowie den Abbau des Cyto-deutero-porphyrins mit Chromsäure, wobei Hämatinsäure und Methylmaleinimid entstehen.

Nach Spektrum und Elementaranalyse war Cyto-deutero-porphyrin von Proto-deutero-porphyrin nicht zu unterscheiden. Aus den Schmelzpunkten der Dimethylester jedoch ging hervor, daß die beiden Porphyrine verschieden sind.

Dieses Ergebnis ist inzwischen dadurch bestätigt worden, daß das Cyto-deutero-porphyrin bei der Bromierung 3 Atome Brom aufnimmt, während Proto-deutero-porphyrin nur 2 Atome Brom aufnimmt. Cyto-deutero-porphyrin scheint also 3 freie β-Stellungen zu enthalten, was K. Zeile auf Grund unsrer Analysen (private Mitteilung) bereits 1953 vermutet hatte. Herr Zeile hat diese Arbeit ferner dadurch unterstützt, daß er 2 Pyrromethene für uns herstellte, nämlich 4.5.5′-Trimethyl-pyrromethen und 4.5.5′-Trimethyl-4′-äthyl-pyrromethen, die zur Gewinnung von zwei neuen Deutero-porphyrinen dienten.

Tabellen über die Schmelzpunkte einiger Deutero-porphyrin-dimethylester und ihrer Bromderivate findet man am Schluß dieser Arbeit. Die Tabellen enthalten die Schmelzpunkte von 4 neuen Deutero-porphyrinen, deren Synthesen in einer anderen Arbeit von Gewitz und Völker beschrieben werden.

Extracellular matrix in deoxycholic acid decellularized aortic heart valves

Background

Only limited information is available regarding the influence of decellularization on the extracellular matrix in heart valves. Within the extracellular matrix proteoglycans (PG) play a central role in the structural organization and physical functioning of valves and in their capability of settling with endothelial and interstitial cells partially myofibroblasts. We have therefore estimated the effects of decellularization using deoxycholic acid on the structure of the extracellular matrix and PG’s in porcine aortic valves.

Material/Methods

Cupromeronic blue was used, alone or in combination with OsO₄/thio-carbo-hydrazide/OsO₄ for electron microscopic visualization. For PG and glycosaminoglycan (GAG) investigation a papain digestion was employed in combination with photometric determination using dimethylmethylene blue.

Results

The results indicate that deoxycholic acid affects the compartmentation of the PG-associated interstitial network not significantly. Compared to controls the PG-rich network was preserved even after deoxycholic acid treatment for 48 h. In parallel to electron microscopy immune assays (ELISA) showed smooth muscle cell α-actin to be reduced to 0.96%±0.71 and total soluble protein to 6.68%±2.0 (n=3) of untreated controls. Protein loss corresponded well with the observations in electron micrographs of rupture and efflux of cell content. Further signs of lysis were irregular cell contours and loss of the basement membrane.

Conclusions

Efficient cell-lysis without disintegration or loss of integrity of the interstitial PG network can be achieved by treatment of aortic valves with deoxycholic acid for 48h. This protocol might also be suitable for clinical use to optimize conditions for growth and autologous remodelling of valves.

[Segmental arterial mediolysis: pathogenesis of aneurysms and dissections in patients younger than 60 years]

BACKGROUND

Complications deriving from arterial aneurysm and dissection without signs of atherosclerosis are rare clinical entities. In recent literature case reports show a descriptive similarity of pathological findings summarized as segmental arterial mediolysis (SAM).

OBJECTIVE

The purpose of this study was to answer the question whether, among 16 patients suffering from SAM histological findings corresponded and assess causality.

MATERIALS AND METHODS

In a prospective prognostic trial sixteen patients were enrolled between 1st January 2008 and 31st October 2011. Inclusion criteria were a lack of atherosclerosis, age under 60 and clinical findings. Most of these sixteen patients were treated as emergency cases of life-threatening blood loss or organ system ischemia. Thirteen of the patients were male, 3 female and their average age was 44 (28-59) years. Localisation of the segmental aneurysm or dissection showed a broad variability from central to renovisceral and peripheral lesions. Imaging diagnostics (e.g., US and CT-A) were complemented by exclusion of positive family history, connective tissue diseases and autoimmune or inflammative disorders. In 8 patients with open vascular reconstructions, it was possible to obtain a biopsy from the target lesion to analyse morphological and immunochemical expression levels (e.g., MMP1-12, vWF, vSMC or CD 68).

RESULTS

None of the patients died nor had described familiar associations. Even the examination of twins with sCAD showed no coincidence. Differential diagnostic findings were excluded. All patients agreed to undergo human genetic screening. The 8 biopsy tissues showed homogeneously mediolysis with focal and increasingly confluent lesions. Main findings were that the vessel wall layering was destroyed and that capillarisation was initiated from the adventitial layer. Furthermore, all patients suffered from hypertension associated to the SAM, or developed it during surveillance.

CONCLUSION

SAM is a rare, life-threatening diagnosis and has to be taken into consideration in young patients with aneurysm and dissection of unusual locations. Rare vascular diseases should have a forum in future investigations which might highlight molecular genetic triggers and associated diseases, e.g., hypertension and aortic type B dissection.

Staphylococcus aureus phenotype switching: an effective bacterial strategy to escape host immune response and establish a chronic infection

Staphylococcus aureus is a frequent cause for serious, chronic and therapy-refractive infections in spite of susceptibility to antibiotics in vitro. In chronic infections, altered bacterial phenotypes, such as small colony variants (SCVs), have been found. Yet, it is largely unclear whether the ability to interconvert from the wild-type to the SCV phenotype is only a rare clinical and/or just laboratory phenomenon or is essential to sustain an infection. Here, we performed different long-term in vitro and in vivo infection models with S. aureus and we show that viable bacteria can persist within host cells and/or tissues for several weeks. Persistence induced bacterial phenotypic diversity, including SCV phenotypes, accompanied by changes in virulence factor expression and auxotrophism. However, the recovered SCV phenotypes were highly dynamic and rapidly reverted to the fully virulent wild-type form when leaving the intracellular location and infecting new cells. Our findings demonstrate that bacterial phenotype switching is an integral part of the infection process that enables the bacteria to hide inside host cells, which can be a reservoir for chronic and therapy-refractive infections.

[Segmental mediolytic arteriopathy (SMA) of central, visceral and peripheral vessels]

HISTORY AND CLINICAL FINDINGS

A 27-year-old man had been admitted to hospital with acute neurological defects involving his legs and urinary system. An intervertebral disk was removed surgically, because a herniation had been suspected. But symptoms increased postoperatively. Further imaging showed a ruptured aneurysm of the internal iliac artery which was treated with coil embolization.

INVESTIGATIONS

Further diagnostic tests excluded hematological, rheumatic and endocrinological causes for the development of the aneurysm. Genetic differentiation was normal. Imaging then demonstrated "string of beads" small aneurysms of intra- and extracerebral, renal, visceral and peripheral arteries.

TREATMENT AND COURSE

During the past three years the patient had repeated ruptures of the intra-abdominal arterial aneurysms for which coil embolization and bypass grafting were performed, also to prevent further ruptures.

CONCLUSIONS

Segmental mediolytic arteriopathy is a rare condition requiring careful imaging and histological tests for its diagnosis and acute surgical treatment.

Morphometric analysis of collagen fibrils in skin of patients with spontaneous cervical artery dissection

BACKGROUND AND AIM

The aetiopathogenesis of spontaneous cervical artery dissection (sCAD) is largely unknown. Electron microscopic (EM) examination of skin biopsies of patients with sCAD revealed very subtle pathological changes of dermal connective tissue in about half of these patients leading to the hypothesis of an underlying connective tissue disorder. However, connective tissue abnormalities did not allow clear discrimination between patients and controls in our hands. Therefore, we sought to establish an objective basis for the assessment of connective tissue abnormalities in patients with sCAD using standardised morphometric assessment of collagen fibrils.

METHODS

In this study a blinded examination was performed of collagen in skin biopsies and it sought parameters which are able to discriminate between patients with sCAD and controls. Various morphometric parameters were compared between patients with sCAD (n = 20) and control subjects (n = 18).

RESULTS

Previously described "flower-like" collagen fibrils in skin biopsies were extremely rare in patients and controls and did not discriminate between the groups. However, they were abundant in the skin biopsy of a patient with Ehlers-Danlos syndrome type III (EDSIII) used as a reference. Morphometric parameters such as collagen fibril diameter, fibril density and relative fibril area did not discriminate between patients and controls on an individual basis, but the mean diameter of collagen fibrils in the skin was lower in patients with sCAD compared with controls while fibril density was higher resulting in nearly equal fibril areas per unit of area (relative fibril area) comparing both groups as well as individuals.

CONCLUSIONS

Blinded pathological and morphometric analysis of collagen fibres in skin biopsies was, in our hands, unable to discriminate reliably between patients with sCAD and controls on an individual basis but did show differences in collagen fibril morphometry on a group basis. Furthermore, systematic and blinded pathological studies of skin biopsies in patients with sCAD and controls are needed.

Exogenous nitric oxide regulates activity and synthesis of vascular endothelial nitric oxide synthase

BACKGROUND

Nitric oxide (NO) - a major signalling molecule of the vascular system - is constitutively produced in endothelial cells (EC) by the endothelial NO synthase (eNOS). Since a reduced NO synthesis is an early sign of endothelial dysfunction and NO delivering drugs are used to substitute the impaired endothelial NO production, we addressed the effect of exogenous NO on eNOS in human umbilical venous endothelial cell cultures.

MATERIALS AND METHODS

The synthetic NO donor DETA/NO (trade name, but in the following we refer to detNO), that releases NO in a strictly first order reaction with a half life of 20 h, was used in our experiments.

RESULTS

Short-term (20-30 min) detNO treatment of EC increases the Ser(1177) phosphorylation of the constitutively expressed endothelial NOS and the production of endogenous NO generated by eNOS from [(3)H]arginine. The phosphorylation of eNOS is Akt-dependent and completely reverted by the phosphatidylinositol-3 kinase (PI-3K) inhibitor LY294002. A prolonged continuous exposure of EC to detNO 150 micromol L(-1) over a period of 24-48 h causes a reversible cell cycle arrest at G(1)-phase associated with a larger cell volume and increased cell protein content (hypertrophic phenotype of EC). The eNOS protein and mRNA of the hypertrophic cells and the generation of endogenous NO are reduced but eNOS phosphorylation could still be elevated by stimulation with vascular endothelial growth factor.

CONCLUSIONS

Our data explain clinical studies describing a short-term but not a long-term benefit of NO treatment for patients with cardiovascular risk factors. The results could be a rational approach to develop a generation of NO donors accomplishing a retarded release from NO donors that mimic the low continuous pulsatile stress-induced release of endogenous NO.

Staphylococcus aureus induces caspase-independent cell death in human peritoneal mesothelial cells

Bacterial peritonitis remains a serious complication of peritoneal dialysis. Although Staphylococcus epidermidis is the most common pathogen involved, infections with Staphylococcus aureus lead to severe peritoneal damage and are often associated with a dramatic loss of mesothelial cells. Induction of cell death appears to be involved in peritoneal damage and mesothelial cell loss during bacterial infections. Using cultured human peritoneal mesothelial cells (HMCs), we investigated the ability of different S. epidermidis and S. aureus strains to damage the HMC monolayer and to trigger cell death. We show that only a subgroup of live S. aureus isolates, characterized by an invasive and alpha-hemolysin-producing phenotype, induces cell death. None of the tested S. epidermidis strains, which were not invasive or hemolytic, had a cytotoxic effect. After host cell invasion, S. aureus resided within phagocytic vacuoles, and HMCs were apparently able to degrade staphylococci. However, even after prolonged infection, a high percentage of S. aureus remained alive within HMCs and might be released after host cell death. Cell death induced by S. aureus was accompanied by apoptotic alterations, such as DNA fragmentation, but was independent of endogenous FasL and tumor necrosis factor-alpha death ligand expression. Moreover, caspases were not involved in S. aureus-induced mesothelial cell death. In conclusion, our data indicate that mesothelial cell death might represent a major mechanism of S. aureus-induced damage of the peritoneum during bacterial peritonitis.

Binding, internalization and transport of apolipoprotein A-I by vascular endothelial cells

High density lipoproteins (HDL) and their main protein constituent, apolipoprotein A-I (apoA-I), exert potentially anti-atherogenic properties within the arterial wall. However, it is unknown how they are transported from the blood stream into the vascular wall. Here we investigated the interaction of apoA-I with endothelial cells. At 4 degrees C endothelial cells bound 125I-apoA-I with high affinity, Kd = 2.1 microg/ml and in a saturable manner (Bmax of 35 ng/mg cell protein). At 37 degrees C, the cell association of apoA-I revealed similar affinity as at 4 degrees C (Kd = 2.2 microg/ml) but the maximum specific cell association was much enhanced (Bmax = 360 ng/mg cell protein). Binding and cell association was competed by excess unlabeled apoA-I and HDL but not by albumin. Biotinylation experiments and electron microscopy studies showed that endothelial cells internalize labeled apoA-I. Only minor amounts of the internalized apoA-I were degraded. Cultivated in a Transwell system, the cells transported a fraction of 125I-apoA-I from the apical to the basolateral compartment in a competable and temperature-sensitive manner. Furthermore, after specific transport the originally prebeta-mobile and lipid-free apoA-I was recovered as particles which have electrophoretic alpha-mobility. We conclude that endothelial cells transcytose and lipidate lipid-free apoA-I.

The antiatherogenic and antiinflammatory effect of HDL–associated lysosphingolipids operates via Akt ➞NF–kappaB signalling pathways in human vascular endothelial cells

Adhesion of mononuclear cells to the vascular endothelium and their subsequent transmigration into the arterial wall represent key events in the pathogenesis of arteriosclerosis. In previous studies we have shown that high density lipoproteins (HDL) and the HDL-associated sphingosylphosphorylcholine (SPC) have the ability to suppress the TNF-alpha-induced expression of endothelial cell E-selectin. However, the current understanding of the mechanism by which HDL reduces the expression of E-selectin is still incomplete. In the present study we show that interaction of the HDL-associated sphingosylphosphorylcholine and sphingosylgalactosyl-3-sulfate (lysosulfatide, LSF) with the G-protein-coupled EDG receptor initiates a signalling cascade that activates the protein kinase Akt and reduces the E-selectin, ICAM-1 and VCAM-1 expression on protein and mRNA level. This signalling cascade is consistently associated with a reduced translocation of TNF-alpha-activated NF-kappaB into the cell nucleus. The suppressor effect of SPC and LSF is completely reverted by inhibition of the phosphatidylinositol- 3-kinase/Akt pathway. We conclude that the antiatherogenic/antiinflammatory effect of lysosphingolipids depends on a competitive interaction of EDG receptor-induced inhibition and TNF-alpha-initiated stimulation of NF-kappaB translocation into the cell nucleus thereby preventing or stimulating inflammatory events in atherogenesis.

Generalized arteriopathy in patients with cervical artery dissection

OBJECTIVE

To make an ultrastructural comparison of superficial temporal artery (STA) biopsy specimens from patients with spontaneous cervical artery dissection (sCAD) and controls.

METHODS

The authors used light microscopic examination of semithin sections and electron microscopic examination of ultrathin sections of STA biopsy specimens from patients with sCAD and controls.

RESULTS

STA biopsy specimens from patients with sCAD taken around the time of the dissection showed a zone of connective tissue weakening with fissuring at the junction between the tunica media (TM) and the tunica adventitia (TA) in seven of nine specimens and erythrocyte infiltration in eight of nine specimens but in none of the control specimens. Light microscopy demonstrated transparent circular spots that, on electron microscopy, turned out to represent erythrocytes and other cellular components at different stages of degradation. Occasionally, scattered immune cells were found in specimens from patients with sCAD. In addition, smooth muscle cells of the synthetic phenotype, some of them showing extensive vacuolation were more common in the TM of STA biopsy specimens from patients with sCAD than in control specimens.

CONCLUSIONS

Signs of tissue weakening along the TM/TA junction in STA biopsy specimens of patients with sCAD but not in controls suggest the presence of a generalized arteriopathy leading to impairment of the stability of the arterial wall in patients with sCAD. Limiting factors of the study are that some control biopsies were obtained from autopsies and that the anticoagulation status of patients and controls were not completely comparable.

Characterization of glycosaminoglycans during tooth development and mineralization in the axolotl, Ambystoma mexicanum

Glycosaminoglycans (GAGs) involved in the formation of the teeth of Ambystoma mexicanum were located and characterized with the cuprolinic blue (CB) staining method and transmission electron microscopy (TEM). Glycosaminoglycan-cuprolinic blue precipitates (GAGCB) were found in different compartments of the mineralizing tissue. Various populations of elongated GAGCB could be discriminated both according to their size and their preferential distribution in the extracellular matrix (ECM). GAGCB populations that differ in their composition could be attributed not only to the compartments of the ECM but also to different zones and to different tooth types (early-larval and transformed). Larger precipitates were only observed within the dentine matrix of the shaft of the early-larval tooth. The composition of the populations differed significantly between the regions of the transformed tooth: pedicel, shaft and dividing zone. In later stages of tooth formation, small-sized GAGCBs were seen as intracellular deposits in the ameloblasts. It is concluded that the composition of GAGCB populations seems to play a role in the mineralization processes during tooth development in A. mexicanum and influence qualitative characteristics of the mineral in different tooth types and zones, and it is suggested that GAGs might be resorbed by the enamel epithelium during the late phase of enamel formation.

Vascular collagens: spotlight on the role of type VIII collagen in atherogenesis

Collagens play a central role in maintaining the integrity and stability of the undiseased as well as of the atherosclerotic vessel wall. An imbalanced metabolism may lead to uncontrolled collagen accumulation reducing vessel wall velocity, frequently resulting in arterial occlusion or thrombosis. A reduced production of collagen and its uncontrolled degradation may affect the stability of the vessel wall and especially of the atherosclerotic plaques by making them prone to rupture and aneurysm. This review presents an overview on the four groups of vascular collagens and on their role in atherogenesis. The major focus was to highlight the extraordinary role and importance of the short chain network forming type VIII collagen in the extracellular matrix of undiseased arteries and of atherosclerotic plaques. The molecular structure of type VIII collagen, its cellular origin, its implication in atherogenesis, its temporal and spatial expression patterns in human and experimental models of atherogenesis, the factors modulating its expression, and--not at least--its potential function is discussed.

Ultrastructure of proteoglycans in tissue-engineered cardiovascular structures

Proteoglycans such as versican, decorin, and perlecan are important components of the extracellular matrix in various tissues. They play an important role in water homeostasis, tissue elasticity, prevention of calcification, and thrombogenicity. The aim of our study was to detect such proteoglycans in engineered tissue and compare them with the proteoglycans of native porcine heart valves. Myofibroblasts were seeded on a type I collagen scaffold. Thereafter, endothelial cells were seeded onto the presettled myofibroblasts. The newly formed tissue was histologically and immunohistochemically examined. Cupromeronic blue was used for ultracytochemical staining of proteoglycans. Radiolabeled proteoglycans were isolated by ion-exchange chromatography and characterized by enzymatic degradation. Three differently sized proteoglycan precipitates were found. The large-sized proteoglycan (154 nm) was located outside the collagen bundles in a rarely structured extracellular matrix compound. The small-sized proteoglycan (46 nm) was aligned along the collagen bundles at intervals of 60 nm. The intermediate-sized proteoglycan (56 nm) was detected on the cell surface of myofibroblasts. The glycosaminoglycans included 80% chondroitin and dermatan sulfate and 20% heparan sulfate. We conclude that proteoglycans play an important role in the functional integrity of cardiovascular tissues. This study shows the successful production of a heart valve-like tissue with proteoglycans resembling, in terms of type, production, and distribution, proteoglycans of native heart valves.

Induction of a hypertrophic growth status of coronary smooth muscle cells is associated with an overexpression of TGF-beta

Hypertrophy of vascular smooth muscle cells occurs during hypertension-induced remodelling of arteries and during development of arteriosclerosis and restenosis following angioplasty but the pathogenesis of the hypertrophic status is not yet fully understood. In a previous study we demonstrated that the synthetic non-sulfated, non-toxic heparin-mimicking compound RG-13577 is capable of inducing a cell cycle-arrested hypertrophic phenotype of coronary smooth muscle cells. In this study we clarify the mode of action of RG-13577 and demonstrate that the RG-13577-induced hypertrophy is associated with an increased expression of TGF-beta1 as indicated by an increase in TGF-beta1-specific protein and mRNA level. Furthermore we show that RG-13577-treated hypertrophic smooth muscle cells maintain full metabolic activity as indicated by a continuous de novo synthesis of protein and proteoglycans and that the RG-13577-induced growth arrest is caused not only by a higher expression of TGF-beta, but also by a reduced response of RG-treated cells to the mitogenic activity of bFGF, PDGF and EGF. The growth inhibitory activity of RG-13577 is reduced in the presence of neutralizing antibodies against TGF-beta. TGF-beta itself has anti-proliferative activity in serum-depleted medium. The RG-13577 effect is reversible since incubation of hypertrophic cells in RG-13577-free medium restores cell volume and [3H]thymidine incorporation to the values of untreated control cells within 4 days. We conclude, that the active metabolic status of RG-13577-treated cells in association with the overexpression of TGF-beta could promote repair processes of injured arteries after angioplasty without stimulating cell proliferation.

Effects of tibolone on the endometrium

OBJECTIVE

To investigate the effects of 24 months of tibolone treatment on the endometrium in postmenopausal women.

DESIGN

An open, prospective, multicenter study with a treatment duration of 24 months.

POPULATION

One hundred and fifty healthy postmenopausal women.

METHODS

Women were treated with one tablet of tibolone (2.5 mg Org OD14) daily. Endometrial biopsies were taken at baseline, 12 months (n = 112) and 24 months (n = 62) to investigate endometrial histology by means of light microscopy.

RESULTS

No stimulation of atrophic endometrium was observed in 98.2% and 91.9% of the analyzed women after 12 and 24 months, respectively. A change from an atrophic endometrial pattern to a weakly proliferative pattern was seen in 1.8% (95% confidence interval (CI) 0.22-6.45) and 6.5% (95% CI 1.20-7.51) of the women after 12 and 24 months, respectively. In one woman, the endometrial pattern after 24 months was classified as simple hyperplasia (1.6%; 95% CI 0.01-3.20). The low incidence of proliferation and/or hyperplasia corresponds to that seen in other clinical trials in which women have been treated with placebo. Vaginal bleeding and/or spotting was reported by 18 women (12%), all showing an atrophic endometrium at all assessments, except for one woman with a proliferative endometrium at 24 months.

CONCLUSION

In the majority of women (92%), the endometrium remained atrophic during 24 months of tibolone treatment.

In vitro modelling of tissue using isolated vascular cells on a synthetic collagen matrix as a substitute for heart valves

BACKGROUND

Tissue engineering is a promising approach for obtaining lifetime durability in biological heart valves. Basic questions with respect to the selection of suitable cell populations as well as scaffolds remain unsolved. The purpose of this study was to develop a tissue-like substitute in vitro for replacement of diseased valves in vivo.

METHODS

Smooth-muscle cells (SMCs) were isolated from human and porcine aortic tissue using the 'explant technique' and endothelial cells from collagenase digestion. Seeding and cultivation of isolated cells was performed on a type-I collagen matrix. The scaffold-cell specimen was investigated using light and electron microscopy. Cupromeronic blue and immunoprecipitation were used for ultracytochemical staining.

RESULTS

SMCs were allowed to grow to multilayers and migrate into the collagen network. We found a tissue-like morphology in these samples characterised by several layers of cells, spaces between the cell layers filled with newly formed extracellular matrix components, compartmentalisation of proteoglycans and their association with fibrilar matrix and the cell surface. Endothelium cells covered the SMCs of the scaffold with a histological topography similar to heart valves.

CONCLUSIONS

This is an approach for in vitro modelling of tissue-like substitutes and preparing plane multicellular tissues as substitutes for heart valves. This model may also be used for cell biological investigations of cell-matrix interactions.

Atherosclerosis in apolipoprotein E-deficient mice is decreased by the suppression of endogenous sex hormones

To elucidate the influence of gonadotropins, endogenous sex hormones and testosterone on atherosclerosis, 4-week-old male and female apoE-deficient mice received either 100 microg subcutaneous injections of the gonadotropin-releasing hormone (GnRH) antagonist Cetrorelix every 48 hours or a subcutaneous implantation of a permeable silastic tube with 35 mg of testosterone. Control mice received either subcutaneous injections of saline, a silastic implant with saline, or no treatment. The animals were sacrificed after eight weeks of treatment; blood was obtained by cardiac puncture and the aorta was taken out and prepared. The suppression of testosterone led to an increase in atherosclerosis in both the sinus aortae and the ascending aorta despite increases of cholesterol in male and decreases of HDL cholesterol in female mice. Treatment with testosterone led to small but significant increases of cholesterol levels and atherosclerotic lesions in male mice. Female mice showed no change in lipids and fewer atherosclerotic lesions. In conclusion, the suppression of gonadotropins appears to have a moderate anti-atherogenic effect. The effect of testosterone appears to be either neutral or opposed by gonadotropins.

[(23)sodium MRI for infarct imaging of the human heart]

PURPOSE

Sodium is elevated in acute/subacute myocardial infarction due to three distinct mechanisms: Breakdown of ion homeostasis with accumulation of intracellular sodium, extracellular edema formation and, during scar formation, increase of extracellular vs. intracellular space as cardiomyocytes are replaced by connective tissue. 23Na MRI has previously been shown to have the potential to demonstrate myocardial infarction in an animal model. Aim of this study was, therefore, to demonstrate myocardial infarction with the use of 23Na-MRI in patients.

MATERIAL AND METHODS

10 patients were examined 14 +/- 7 days after first myocardial infarction using a 23Na surface coil at 1.5 T. Double angulated short axis images of the entire heart were imaged using an ECG-triggered 3d-FLASH-sequence (FOV, 450 mm; matrix, 64 x 128; spatial resolution, 3.5 x 7 mm2; slice thickness, 16 mm; 32 acquisitions). Areas of elevated sodium signal intensity were correlated with infarct-related wall motion abnormalities imaged by Cine MRI in breathhold-technique.

RESULTS

All patients showed an area of elevated sodium signal intensity that correlated well with the clinically determined localization of myocardial infarction as well as with regional wall motion abnormalities detected by Cine MRI.

CONCLUSIONS

Elevated 23Na MR image signal intensity demonstrates subacute myocardial infarction in patients.

Differentiation of coronary smooth muscle cells to a cell cycle-arrested hypertrophic growth status by a synthetic non-toxic heparin-mimicking compound

Studies on the mode of action of basic fibroblast growth factor (bFGF) identified an essential role of heparan sulfate and heparin-like molecules in the formation of distinct bFGF-heparan sulfate-bFGF-receptor complexes that are required for bFGF-induced signal transduction. In coronary smooth muscle cells that express 6-8 ng bFGF mg(-1) cell protein, the heparan sulfate chains of membrane-associated proteoheparan sulfate are implicated in bFGF signaling and thus are involved in the regulation of proliferation and differentiation of vascular smooth muscle cells. We studied the mode of action of a synthetic non-sulfated heparin-mimicking compound termed RG-13,577 (poly-4-hydroxyphenoxy acetic acid, Mr approximately 5 kD) and found a dose-dependent antiproliferative effect that was characterized by a block of G(1)/S-phase transition indicated by a marked (80%) reduction of [3H]thymidine incorporation at a concentration of 5 microg ml(-1) RG-13,577. Cell cycle analysis showed a block of cell division in the G(1)-phase. In response to RG-13,577 the cells were converted into a hypertrophic growth status within 72 h as judged from a doubling of the cellular protein content and measurement of cell and nucleus size. The increased cell protein content resulted from a de novo synthesis and was also associated with an increase in the incorporation of [35S]sulfate into cell-associated proteoglycans, including the proteoheparan sulfate coreceptor of bFGF. In contrast, the compound-induced G(1)-phase arrest was associated with an extensive downregulation of the cellular and pericellular bFGF level. The reduced bFGF content was accompanied by downregulation of the bFGF signaling-involved protein kinase C-alpha and MAP kinase, abrogation of MAP kinase phosphorylation and overexpression of protein kinase C-gamma. RG-13,577 failed to elicit apoptotic reactions at a concentration range of 0.5-10 microg ml(-1) and its effect was reversible upon removal of the compound. It appears that RG-13,577 induces a phenotype transformation of coronary SMC into a metabolically active hypertrophic status that could promote repair processes after balloon angioplasty (PTCA) without stimulating cell proliferation. Development of non-toxic polyanionic compounds may provide an effective strategy to inhibit cell proliferation associated with restenosis following balloon angioplasty and coronary artery bypass surgery.

Cholesterol-induced changes of type VIII collagen expression and distribution in carotid arteries of rabbit

Lipoproteins play a major role in cardiovascular disease and atherosclerosis. In the vascular wall, they strongly influence the organization of extracellular matrix. The present study set out to investigate the changes in the extracellular matrix of the vessel wall induced by atherogenic diet, focusing on type VIII collagen, a vascular collagen that has not previously been investigated in detail. The influence of cholesterol diet on the expression, distribution, and deposition of type VIII collagen was examined in carotid arteries of New Zealand White rabbits. Carotid arteries of rabbits receiving diet supplemented with 1% cholesterol for 6 weeks and those on the same regimen followed by normal chow for 1 day, 10 days, 5 weeks, and 12 weeks were studied and compared with controls not exposed to the cholesterol diet. Carotid arteries of normocholesterolemic rabbits contained type VIII collagen-expressing cells in all layers, with focal accumulations of expressing cells in the subendothelial areas, the outer medial zone, and the adventitia. In response to cholesterol diet, type VIII collagen synthesis was reduced in media and adventitia and the distribution patterns changed. Expressing cells were found predominantly in the endothelium, and type VIII collagen accumulated in the intimal space. Immunogold labeling for electron microscopy revealed that type VIII collagen in the intima is associated with microfibrils extending from the internal elastic lamina. Withdrawal of cholesterol resulted in reestablishment of the normal distribution pattern. Northern and Western blot analyses supported the immunoconfocal and in situ hybridization data, demonstrating decreased type VIII collagen expression in response to cholesterol diet and progressive recovery to normal levels with time after withdrawal of cholesterol. Our study demonstrates that type VIII collagen is modulated in the presence of cholesterol. The data indicate that type VIII collagen is specifically remodeled during early experimental atherosclerosis, implying a role for this extracellular matrix component in neointimal growth.

Perlecan is responsible for thrombospondin 1 binding on the cell surface of cultured porcine endothelial cells

Thrombospondin 1 (TSP1), a high molecular weight glycoprotein of the extracellular matrix, interacts with glycosaminoglycan at the cell surface of porcine endothelial cells (Schön et al., Eur.J. Cell Biol. 59, 329-339 (1992)). In this study we identified and characterized the heparan sulfate proteoglycan (HSPG) responsible for TSP1 binding and uptake in endothelial cells and investigated some properties of the TSP1-proteoglycan interaction. Porcine endothelial cells synthesize proteoglycans containing heparan sulfate (HS) or chondroitin/dermatan sulfate (CS/DS). CS/DS-containing compounds are present predominantly in the culture medium. On Sepharose CL-4B the cellular proteoglycan fraction yielded two HS-containing compounds with a Kav = 0.18 and Kav = 0.55. Only the larger HS-containing component was sensitive to alkaline treatment and was also found in the medium fraction. Trypsin treatment of endothelial cells revealed that the large HS-containing component represents a cell surface-associated proteoglycan, whereas the smaller fraction represents a pool of intracellular HS-chains. The cellular HSPG is partially localized at the apical cell surface but also incorporated and tightly bound to the subendothelial matrix. Deglycosylation of the high molecular weight HSPG resulted in the identification of a core protein of about 400 kDa. Using specific antibodies, in ELISA assays and in immunoblot analysis we observed that the large HSPG is identical to the extracellular matrix proteoglycan, perlecan. Immunohistochemical studies confirmed the location of perlecan on the apical cell surface and additionally as a dense fibrillar network surrounding the cells. Purified perlecan bound to TSP1 in a dose-dependent manner and the binding was mediated by its glycosaminoglycan side chains. In competition assays using various sulfated polysaccharides, heparin potently inhibited binding of perlecan to TSP1 immobilized on nitrocellulose. Dermatan sulfate was a less effective inhibitor. Calcium bound to TSP1 was found to influence its capacity for binding perlecan. The present data provide evidence that perlecan is required for binding and concentrating TSP1 at the apical surface of vascular endothelial cells during receptor-mediated endocytosis.

Copper-induced inflammatory reactions of rat carotid arteries mimic restenosis/arteriosclerosis-like neointima formation

The pathogenesis of arteriosclerosis and of restenosis after angioplasty is linked with an inflammatory and fibroproliferative response of the arterial tissue. We have induced a non-infectious inflammation by implanting a silicon-copper cuff around rat carotid arteries. The copper ions released from the oxidized copper initiate and mimic all morphological features of post-angioplasty restenotic and arteriosclerotic lesions. The copper-induced lesions were analyzed by electron and light microscopy, immunohistochemical methods and quantified by morphometry. During the first phase of copper-induced tissue reaction (3 days), macrophages and polymorphonuclear leucocytes invaded through the endothelium, accumulated in the subendothelial space and triggered the proliferation of smooth muscle cells which then migrated from the tunica media through the lamina elastica interna into the intima. Within 3 weeks, the accumulated smooth muscle cells, macrophages, leucocytes and newly synthesized extracellular matrix formed a circular mostly eccentric fibrotic thickening that narrows the vessel lumen by 30-40%. The accompanying structural disorganization of the medial layer led to focal rupture and aneurysm-like dilatation of the vessel wall in 3 of 11 animals between day 20 and 43. The neointima progressively increased in thickness over time leading to corresponding reduction of the vessel lumen. The carotid arteries of control animals and animals treated with copper-free silicon cuffs showed no abnormal pathological appearance. Our results show that inflammation-inducing agents can contribute to and simulate restenosis- and arteriosclerosis-like lesions and that the copper-cuff model may be useful in the exploration of new approaches to intervention.

Pyrogallol red-vanadium complex-a new stain for electron microscopy

We report on the application of a pyrogallol red-vanadium complex (PR-V) for ultracytochemical staining of proteinaceous structures in animal tissues and cell cultures. This dye may be used as a general purpose stain in electron microscopy. In contrast to osmium tetroxide, the price of the material is low and no toxic vapors are produced. The PR-V complex was prepared by addition of vanadium (IV) oxide sulfate to pyrogallol red dissolved in acetate buffer (pH 5.6). The formation of the complex was indicated by a color change from purple-red (lambda max = 520 nm) to violet (lambda max = 539 nm) which occurred at equimolar concentrations of the dye and the metal salt. Under these conditions PR-V was stable for several days. The mechanism of PR-V binding was checked in dot blots using different proteins as well as heparin for control. While heparin remained unstained, proteins were stained in a dose-dependent manner. Deamination of proteins with nitric oxide strongly reduced PR-V staining in dot blots as well as in cell cultures. Optimal staining results of animal cells and tissues were obtained in specimens that had been mildly fixed for at least 1 h or longer with a mixture of 0.1% glutaraldehyde and 1.0% paraformaldehyde dissolved in phosphate-buffered saline, pH 7.2, washed with acetate buffer, pH 5.6, and subsequently treated with PR-V in the presence of 50% ethanol at room temperature. Control specimens without PR-V but treated en bloc with uranyl acetate or sodium molybdate showed similar contrast but less details in the ultrastructure of the tissue. All specimens were embedded in epoxy resin and ultratain sections were stained conventionally with uranyl and lead salt solutions. In electron micrographs, membrane-associated particles, stress fibers and filaments of the cell cortex, collagen fibrils, tight junctions and desmosomes, and other proteinaceous components were clearly visualized only in the PR-V-treated specimens. In conclusion, the ability to bind selectively and specifically to protein-aceous structures makes PR-V a versatile stain to study the localization and distribution of these structures in cells and tissues at the ultrastructural level.

Cholesterol-dependent changes of glycosaminoglycan pattern in human aorta

Glycosaminoglycans are regular constituents of the arterial wall and essential for its structure and function. The arteriosclerosis-dependent changes of glycosaminoglycans were investigated, the degree of arteriosclerosis was monitored by the cholesterol content of the tissue. Histological characterization was achieved by electron microscopy. Total glycosaminoglycans were isolated from 33 delipidated segments of human aorta thoracica after exhaustive proteolytic digestion, and fractionated into the individual glycosaminoglycans by a multistep purification procedure. Chondroitin sulfate (CS), dermatan sulfate (DS), heparan sulfate (HS), and hyaluronate (HA) were identified and quantified by chemical and enzymatic analysis. The concentration of total and individual glycosaminoglycans, expressed as mg/g delipidated dry weight of tissue, decreased significantly with increasing cholesterol content of tissue (p = 0.0005-0.005). The extent of decrease differed between the individual glycosaminoglycans as indicated by a shift in the CS/DS:HA:HS ratio from 47:32:21 in low cholesterol aortic segments to 59:29:12 in cholesterol-rich specimens. Determination of the relative molecular masses (Mr) revealed 58 kDa for CS/DS and 92 kDa for HS with a (statistically not significant) increase of the molecular mass of CS/DS and a decrease of HS with increasing cholesterol content. The copolymeric CS/DS glycosaminoglycans were disintegrated enzymatically into CS and DS containing fragments. A significantly higher relative DS content (p = 0.01) was found in cholesterol-rich arterial tissue (32.5%) as compared with low cholesterol tissue samples (28.8%). Cell culture experiments revealed that human arterial HS is able to inhibit the proliferation of cultured human arterial smooth muscle cells. The HS concentration required for a 30% inhibition of smooth muscle cell proliferation was in the same order as the tissue concentration of HS. This confirms the function of HS as an endogenous inhibitor of cell division and its impact for the development of atherosclerosis.

Antibodies against proteins of streptococcal hyaluronate synthase bind to human fibroblasts and are present in patients with rheumatic fever

Antibodies directed against the streptococcal 42 kDa hyaluronate synthase and a 56 kDa auxiliary protein bound to the surface of intact human fibroblasts in vitro. Staining was most prominent during the detachment phase of mitosis. In eukaryotic plasma membranes a 52 kDa protein was recognized by the antiserum against the 56 kDa streptococcal protein. Since the cross-reacting proteins could be involved in immunological mimicry between streptococcal and human antigens leading to heart cell necrosis, the reactivity of sera from patients with rheumatic fever was compared with that of sera from healthy or streptococcal infected persons. The sera from patients with rheumatic fever showed a higher reactivity against the 56 kDa protein than those from healthy persons or from patients with an antibiotic treated streptococcal infection. This difference was not observed for the 42 kDa protein. These sera were able to lead to cell lysis in the presence of complement.

Inhibition of smooth muscle cell proliferation and neointimal growth by low-anticoagulant heparin

Low-anticoagulant heparin (LA-heparin) obtained by affinity chromatography on antithrombin III Sepharose inhibits the proliferation of cultured arterial smooth muscle cells in an in vitro bioassay system as effectively as standard heparin. A growth inhibition of smooth muscle cells of about 60% is achieved when LA-heparin or heparin is added to the culture medium to a concentration of 50 micrograms/ml. In normolipemic rats LA-heparin suppresses the formation of neointimal thickenings and stenosis after balloon catheter-induced deendothelialization of the carotid artery. In terms of mass a dose of 5 mg/kg body weight/d given subcutaneously twice daily one week before and 2 weeks after balloon injury the cross sectional area of the neointima is reduced to 36% as compared with the nontreated control group (100%). This 64% reduction is statistically highly significant (p < 0.001). After treatment with 0.5 mg LA-heparin/kg/d the reduction of the neointima was 11% (p < 0.05). At a dose of 5 mg/kg body weight single or repeated administrations of LA-heparin caused only a small and transient increase in activated partial thromboplastin time values. The results show that subcutaneous administration of LA-heparin very effectively prevents smooth muscle cell proliferation and balloon catheter-induced neointimal growth. The well tolerated systemic application of this chemically non-modified LA-heparin might justify clinical trials for prevention of restenosis after percutaneous transluminal coronary angioplasty or other invasive cardiovascular interventions without complications of bleeding.

Binding and processing of multimeric vitronectin by vascular endothelial cells

The multifunctional adhesive glycoprotein vitronectin (VN) undergoes a unique conformational transition from the plasma form into a multimeric form that represents the reactive heparin-binding form. In this study we investigated the interaction of multimeric vitronectin (VNmult) or VN-gold conjugates (which are equivalent in biochemical properties) with confluent and subconfluent monolayers of porcine endothelial cells. Time-dependent direct binding of radiolabeled VNmult to the luminal face of endothelial cells at 37 degrees C was observed which was competed by heparin, whereas plasma VN showed hardly any binding. At 4 degrees C binding of VNmult remained cell-associated, whereas after 6 hr at 37 degrees C a major portion of the ligand was translocated through cells and was associated with the subcellular matrix. Cytochemical studies with VN-gold conjugates were performed to demonstrate uptake of VNmult. At 4 degrees C only surface decoration of cells with gold label was seen, which was totally reversible in the presence of heparin. Subsequent incubation for various time intervals at 37 degrees C revealed disappearance of gold label from the surface and accumulation of conjugates in a perinuclear distribution inside the cells as judged both by electron microscopy and after silver enhancement by light microscopy. Cross-sections of endothelial cells demonstrated the inclusion of VN-gold conjugates in coated pits, endosomes, and in lysosomal compartments close to the nucleus. Within 2-6 hr a portion of VN-gold conjugates had accumulated with proteoglycans at the matrix face. These data provide strong evidence for specific routing of a portion of VNmult from the circulation into extravascular spaces, where the protein is believed to fulfill major adhesive and regulatory functions particularly as co-factor in plasminogen activation and immune defense.

Lectin binding and uptake and glycoprotein characterization of isolated porcine aortic endothelial and smooth muscle cells

Endothelial and smooth muscle cells were isolated from porcine aorta and kept in short-term culture. To determine the terminal carbohydrate composition of the plasma membranes from both cell populations, the cells were incubated with a panel of fluorescein-labelled lectins. Both cell populations shared a number of terminal carbohydrates, but the N-galactosamine specific lectin Wistaria floribunda agglutinin labelled only endothelial cells. A lectin which selectively labelled smooth muscle cells was not found. Western blot analysis of isolated endothelial cell membrane glycoproteins indicated that most membrane glycoproteins are labelled by Wistaria floribunda agglutinin.

Cell-associated proteoheparan sulfate mediates binding and uptake of thrombospondin in cultured porcine vascular endothelial cells

[125I]Thrombospondin (TSP) binds to porcine endothelial cells in a specific, saturable and time-dependent fashion and is endocytosed by a receptor-mediated process. The N-terminal heparin-binding domain is necessary for the interaction with the cell surface. Binding and uptake is inhibited by heparin and to a much smaller extent by other vascular glycosaminoglycans. Chemical modification of lysine and arginine residues of TSP, but not treatment of the molecule with neuraminidase, resulted in a pronounced loss of binding at the cell surface. Treatment of cells with heparitinase but not with chondroitin ABC lyase caused inhibition of binding and uptake of TSP. Inhibition of sulfation of proteoglycans on the cell surface by chlorate leads to a dose and time-dependent inhibition of binding and degradation of TSP. In the presence of chlorate, newly synthesized TSP is not incorporated into the cell matrix but mainly released into the culture medium, whereas localization and incorporation of newly synthesized fibronectin is not altered. A cell surface proteoheparan sulfate was identified as TSP binding macromolecule by affinity chromatography. The data emphasize the role of heparan sulfate proteoglycan as a receptor-like molecule for the specific interaction with thrombospondin.

Colocalization of a large heterodimeric proteoglycan with basement membrane proteins in cultured cells

A novel large heterodimeric dermatan sulfate proteoglycan with core proteins of 460 and 300 kDa, respectively, had been described as a secretory product of human fetal skin fibroblasts (Breuer et al., J. Biol. Chem. 266, 13224-13232 (1991)). Pulse-chase experiments showed a preferential association of the proteoglycan with the cell membrane. Immunogold labeling indicated its localization in fibrils on the cell surface as well as in fibrillar extensions from the cell body. Immunofluorescence studies yielded a fibrillar and punctate staining pattern which was also seen in cultured human and porcine endothelial cells. Dot-like structures were observed in transformed human keratinocytes. Various immunocytochemical double-labeling experiments indicated a remarkable colocalization of the proteoglycan with fibronectin, laminin, perlecan, and type IV collagen whereas only occasionally a colocalization with chondroitin-6-sulfate was found. No evidence for an enrichment of the proteoglycan in vinculin-containing structures was obtained. These results suggest that the proteoglycan is a widely distributed macromolecule which can associate with basement membrane components. Preliminary findings in rat cornea supported this conclusion.

Stimulation of the biosynthesis of lactosamine repeats in glycoproteins in differentiating U937 cells and its suppression in the presence of NH4Cl

We prepared a mouse monoclonal antibody, 2D5, which recognized a highly glycosylated human lysosomal membrane antigen. The apparent molecular mass of this antigen was cell type dependent and ranged between 100 kDa and 130 kDa. The difference was due to a variation in the carbohydrate moiety, since upon removal of the N-linked oligosaccharides the size of the glycoprotein was reduced to approximately 50 kDa in all cases. The high carbohydrate contents, subcellular localization and N-terminal sequence indicated a high similarity or identity of this antigen with the lamp-2 protein. In U937 cells several agents known to elicit differentiation induced synthesis of a larger form of the lamp antigen. Thus, treatment of cells with calcitriol resulted in a shift in its average molecular mass from 115 kDa to 130 kDa. The difference was due to an increase in the contents of lactosamine repeats. In subcellular membranes from calcitriol-treated cells the specific activity of the UDP-N-acetylglucosamine: N-acetyllactosamine N-acetylglucosaminyltransferase was enhanced 3-fold. The enhancement was accompanied with an elongation of lactosamine repeats in N-linked oligosaccharides in the 46 kDa mannose 6-phosphate receptor and the homing receptor, the leucocyte antigen CD44. In contrast, the apparent size of the leucocyte antigen CD43 which bears numerous O-linked oligosaccharides was not changed indicating a selectivity in the modulation of the formation of lactosamine repeats in N- and O-linked carbohydrates. It is shown further that the synthesis of lactosamine repeats in U937 cells is impeded in the presence of NH4Cl.

Binding and endocytosis of thrombospondin and thrombospondin fragments in endothelial cell cultures analyzed by cuprolinic blue staining, colloidal gold labeling, and silver enhancement techniques

We investigated the distribution of thrombospondin-specific binding sites and the uptake of thrombospondin-gold conjugates in cultured porcine endothelial cells by light and electron microscopy. Colloidal gold marker and silver enhancement techniques were applied for cytochemical detection of monomeric thrombospondin and fragments of thrombospondin. Thrombospondin binds to granular and fibrillar structures and to sites of cell-cell contact on the cell surface, as indicated by many proteoglycan-cuprolinic blue precipitates. Cell migration tracks on the culture dish bottom are most heavily stained. Labeling of intact thrombospondin and of proteolytic fragments of thrombospondin with colloidal gold followed by silver intensification enables one to detect its binding and uptake in endothelial cells. Binding to the cell surface and uptake of thrombospondin-gold particles was inhibited by heparin but not by hyaluronic acid or chondroitin sulfate. The heparin binding region at the N-terminal end of the thrombospondin molecule proved to be essential for cell surface binding. Gold-conjugated thrombospondin fragments devoid of the heparin binding region were not internalized. After 60 min incubation at 37 degrees C, thrombospondin-gold particles accumulated in the lysosomal compartment close to the nucleus. In the presence of monensin and ammonium chloride, vesicles in this area are swollen and the concentration of particulate marker is reduced. Binding and uptake of thrombospondin by vascular endothelial cells appears to require linkage of the heparin binding region of the thrombospondin molecule to coated pits and heparan sulfate-rich molecules as receptors. Colloidal gold conjugation of thrombospondin fragments proved to be useful for cytochemical characterization of molecular domains.

Aspirin reduces the growth of medial and neointimal thickenings in balloon-injured rat carotid arteries

We analyzed the effect of Aspirin on the growth of experimentally induced vascular thickenings in rat carotid arteries. Vascular thickenings were induced by denudation of the endothelium in the left carotid artery with a balloon catheter. Administration of Aspirin-rich food (17.4 g/kg body wt/day) was started 1 week before and continued 2 weeks after injury. Nine rats were used. A control group of equal size received normal food. Sizes of the tunica media, the neointima, and the open vessel lumen were measured on cross sections of carotid segments with the aid of a videomorphometry system. The results show that in the Aspirin group, neointimal lesions are significantly smaller than in the control group (0.14 mm2 versus 0.23 mm2; p less than 0.5). Thickenings of the tunica media are also reduced (0.11 mm2 versus 0.12 mm2; p less than 0.5). It is suggested that Aspirin reduces both medial hypertrophy and neointimal outgrowth in injury-induced atherosclerosis.

[Results of emergency aortocoronary venous bypass surgery after failed percutaneous transluminal coronary angioplasty in patients with unstable angina pectoris]

During a 4-year period from January 1985 to December 1988 140 patients underwent percutaneous transluminal coronary angioplasty (PTCA) of the culprit-vessel for unstable angina. Seventeen patients (12%) needed emergency aorta coronary bypass surgery (ACVB) for failed angioplasty. In 15 cases the culprit-vessel was the LAD and in 2 cases a dominant right coronary artery. Only in 2 cases a history of myocardial infarction was present. Twelve patients were in hemodynamic stable condition after arriving in the operating-room. Five patients were hemodynamic unstable, 4 of them were in cardiogenic shock. Four patients died representing an operative mortality rate of 23%. Three patients died from pump failure despite intraaortic balloon counterpulsation in 2 cases. One patient died from cerebral damage 12 day after surgery. All patients who died were in cardiogenic shock preoperatively. Two patients who survived suffered an extensive myocardial infarction. Thus including the patients who died from pump failure the perioperative infarction rate was 30%. From these results it is concluded that emergency ACVB after failed PTCA of the culprit-vessel in patients with unstable angina results in a significant higher mortality and morbidity as compared with patients who had primary surgery for unstable angina. The prognosis of patients after failed PTCA for unstable angina depends on the hemodynamic situation thereafter and becomes worse in patients with cardiogenic shock.