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Biomedical subjects

L Bengtsson

Publications and source records attributed to L Bengtsson.

At least 37 records · Page 2Linked to original sources
PubMed1995

Studies on the biosorption of uranium by Talaromyces emersonii CBS 814.70 biomass.

Residual biomass, produced by the thermophilic fungus, Talaromyces emersonii CBS 814.70, following growth on glucose-containing media, was examined for its ability to take up uranium from aqueous solution. It was found that the biomass had a relatively high observed biosorption capacity for the uranium (280 mg/g dry weight biomass). The calculated maximum biosorption capacity obtained by fitting the data to a Langmuir model was calculated to be 323 mg uranium/g dry weight biomass. Pretreatment of the biomass with either dilute HCl or NaOH brought about a significant decrease in biosorptive capacity for uranium. Studies on the effects of variation in temperature on the biosorptive capacity demonstrated no significant change in binding between 20 degrees C and 60 degrees C. However, a significant decrease in biosorptive capacity was observed at 5 degrees C. Binding of uranium to the biomass at all temperatures reached equilibrium within 2 min. While the routine binding assays were performed at pH 5.0, adjustment of the pH to 3.0 gave rise to a significant decrease in biosorption capacity by the biomass. The biosorptive capacity of the biomass for uranium was increased when extraction from solution in sea-water was examined.

Adsorption↗
PubMed1995

Reduction of monocyte adhesion to xenogenic tissue by endothelialization: an adhesion molecule and time-dependent mechanism.

Great interest has been shown for the seeding of autologous endothelial cells on prosthetic materials. We investigated the inflammatory and immunogenic properties of xenogeneic tissue before and after seeding with cultured human great saphenous vein endothelial cells in vitro. Adhesion of monocytes to xenogeneic tissue with or without endothelium and the endothelial cell expression of E-selectin, intercellular adhesion molecule 1, vascular adhesion molecule 1, and major histocompatibility complex class II antigens were investigated 1, 3, and 7 days after seeding. Both monocyte adhesion and endothelial adhesion molecule expression were relatively high 1 day after seeding and were significantly lowered after 3 to 7 days. There was no difference between monocyte adhesion and adhesion molecule expression on viable or nonviable xenogeneic tissue. Monocyte adhesion and adhesion molecule expression increased after interleukin-1 beta or interferon-gamma stimulation of the endothelial cells. The results suggest that human endothelial cells exhibit an early proinflammatory and immunogenic activity immediately after seeding. Three and 7 days after seeding, the endothelialized surface is less adhesive for monocytes as compared with nonendothelialized tissue. These findings have implications when cultured or intraoperatively recruited endothelial cells are used clinically.

Animals↗
PubMed1994

A new and simple technique to achieve a confluent and flow resistant endothelium on vascular ePTFE-grafts using human serum.

Confluent endothelialisation of vascular grafts in vitro before implantation has been suggested as a way to improve patency. With the aim of creating a confluent endothelium or expanded polytetrafluoroethylene (ePTFE) vascular grafts, using a minimum of allo- or xenogenic material, we have investigated the use of human serum for endothelial cell (EC) growth and adhesion to the grafts. Loss of fibronectin from the serum was measured before and after coating. After serum- or collagen I-precoating, the grafts were seeded with cultured adult human endothelial cells from the great saphenous vein and then kept under rotational culture conditions for 2 days. To evaluate the endothelial resistance to detachment the grafts were mounted in parallel to a heart-lung machine, delivering a pulsatile flow of human blood for 1 hour. Evaluation was performed using scanning electron microscopy (SEM). By simply pressing serum through the graft wall, fibronectin corresponding to 19 micrograms/cm2 graft surface was consumed. It was possible to achieve a confluent endothelium on both serum- and collagen I-precoated grafts (n = 8). After being subjected to blood flow, SEM revealed a complete endothelial lining of the grafts (n = 12) except for two serum-precoated grafts which showed < or = 10% and between 10 and 20% denuded areas, and one collagen-coated graft that showed < or = 10% of denuded area. This method provides a way to achieve a confluent and flow resistant endothelial lining on ePTFE vascular grafts.

Blood↗
PubMed1994

An outbreak of Legionnaires' disease in a Swedish hospital.

We report a nosocomial outbreak of Legionella pneumophila serogroup (sg) 1 infection at the general hospital, Värnamo, Sweden. From December 1990 to February 1991, 28 patients and 3 staff fell ill with pneumonia and 3 died. L. pneumophila sg 1 together with several other Legionellae were isolated from the hot water supply to 17 of 20 hospital wards, probably being spread by aerosolization via shower nozzles. Raising the hospital's hot water temperature from 45 degrees C to 65 degrees C, together with heat disinfection of the shower equipment, arrested the outbreak within a week. Keeping the hot water temperature > or = 60 degrees C without chlorination eliminated L. pneumophila from > 75% of the wards. During a period of 2 years after the outbreak we have diagnosed only 1 case of nosocomial legionellosis at the hospital despite an active surveillance program.

Aged↗
PubMed1994

Rapid visualization of viable and nonviable endothelium on cardiovascular prosthetic surfaces by means of fluorescent dyes.

Increasing interest in endothelialization of synthetic and tissue cardiovascular prostheses in vitro emphasizes the need for simple and rapid methods to evaluate presence of endothelium on surfaces. Scanning electron microscopy is a commonly used method for this purpose. In this study we investigated alternative and more rapid staining methods. Human saphenous vein endothelial cells in culture and on cardiovascular prosthetic materials (pyrolytic carbon, cusps of bioprosthetic heart valves, pig aorta, and expanded polytetrafluoroethylene) were labeled by exposing them to medium containing 5-chloromethylfluorescein diacetate or 1,1-dioctadecyl-3,3,3',3'-tetramethylindo carbocyanine perchlorate. For comparison, specimens were also fixed and processed for scanning electron microscopy. A bright fluorescence of endothelial cells labeled with 5-chlormethylfluorescein diacetate or 1,1-deoctadecyl-3,3,3',3'-tetramethylindo carbocyanine perchlorate wre clearly visualized in culture, on pyrolytic carbon, and on expanded polytetrafluoroethylene. Unfixed, prelabeled cells could be visualized immediately and unlabeled cells could be investigated for viability within 1 hour. Cells seeded on biologic tissue specimens could be visualized within 15 minutes with a modified hematoxylin-eosin staining. We suggest the use of these methods for rapid visualization of endothelium present on surfaces of cardiovascular prosthetic materials where they can partly replace the use of scanning electron microscopy.

Bioprosthesis↗
PubMed1993

In vitro endothelialization of commercially available heart valve bioprostheses with cultured adult human cells.

The possibility of improving the performance of heart valve bioprostheses by preendothelialization with autologous cells has been suggested. In this study we used cultured adult human vein endothelial cells to endothelialize cusps isolated from commercially available porcine valve bioprostheses. We also describe a method for primary endothelialization of the intact heart valve bioprosthesis. After detoxification of the glutaraldehyde, the cusps or valves were seeded at high density with cultured cells. To obtain an even distribution on the intact valve bioprosthesis, a device was designed which permits application of cells from different directions during rotation. Evaluation was performed by hematoxylin-eosin staining, scanning electron microscopy and immunohistochemistry of the von Willebrand factor and the human basement membrane constituent collagen IV. The endothelial cells were vital-stained during culture by the addition to the culture medium of carbocyanine dye. This made it possible to verify that the endothelium was derived from culture. A confluent lining of cultured endothelial cells in close proximity to a de novo formed basement membrane was observed on the isolated cusps 7 days after seeding. The intact heart valve bioprosthesis showed an even distribution of seeded cells with areas of cells spreading to confluency as evaluated after 24 h. However, 7 days after seeding only unspread and probably dead cells were observed.

Bioprosthesis↗
PubMed1993

Serum proteins provide a matrix for cultured endothelial cells on expanded polytetrafluoroethylene vascular grafts.

Endothelialization of prosthetic vascular grafts has been shown to increase patency. We studied the adhesion of cultured endothelial cells of adult human saphenous vein to serum protein coating on expanded polytetrafluoroethylene vascular grafts. The adhesion was compared with that on native or collagen type I-coated grafts. Scanning electron microscopy was used to analyze the precoating and the appearance of the added cultured cells. Presence of radioactively labeled saphenous vein endothelial cells was compared between precoated and uncoated grafts before and after exposure to pulsatile plasma flow. The adherence of saphenous vein endothelial cells was markedly increased on grafts coated with serum proteins or collagen. On both graft types the cells formed confluent areas, which were also present after the plasma flow. The technique was designed to promote endothelialization, using autologous serum as the main source for both growth stimulation during culture and adherence of endothelial cells to grafts. The method may be clinically useful for precoating and endothelialization of vascular grafts.

Blood Proteins↗
PubMed1993

Lining of viable and nonviable allogeneic and xenogeneic cardiovascular tissue with cultured adult human venous endothelium.

With the aim of creating a confluent endothelial lining of cultured adult human saphenous vein endothelial cells on cardiovascular bioprosthetic tissues in vitro, we performed seeding on deendothelialized segments of viable or devitalized (in deionized water) human vein, porcine aorta, and bioprosthetic tissues preserved in glutaraldehyde. After being seeded, specimens were kept for 7 days under culture conditions. On glutaraldehyde-preserved tissue, seeding was performed after 3 weeks of elution of glutaraldehyde. Evaluation was performed with hematoxylin-eosin staining, immunohistochemical staining of von Willebrand's factor and of collagen IV-related antigens, and scanning and transmission electron microscopy. The origin of the cells as derived from culture was verified by vital staining with a carbocyanine dye. Evaluation revealed a confluent lining of cultured human saphenous vein endothelial cells similar to native endothelium on both viable and nonviable human and porcine tissues. Collagen IV-related immunoreactivity was demonstrated close to the endothelial cells, corresponding to a de novo-formed basement membrane. Organelles and a basement membrane were demonstrated by transmission electron microscopy. The human saphenous vein endothelial cells seeded on glutaraldehyde-preserved tissues showed initial adherence but rounded up and detached on the second day of culture, probably because of residual glutaraldehyde. This study demonstrates that the native endothelium of allogenic or xenogeneic viable and nonviable vascular tissue may be replaced by cultured endothelium in vitro. The structural similarities with a native endothelium suggest that in vitro endothelialization with cultured autologous endothelial cells may be used to improve performance of cardiovascular bioprostheses.

Adult↗
PubMed1992

Labeling with fluorescent carbocyanine dyes of cultured endothelial and smooth muscle cells by growth in dye-containing medium.

We describe a method for labeling cultured endothelial cells (ECs) and smooth muscle cells (SMCs) by letting the cells grow for three days in culture medium containing a low concentration of the fluorescent carbocyanine dyes DiI and DiO. We show that good labeling can be obtained with considerably lower concentrations (2.5 micrograms/ml) than has previously been described. With optimal concentration the labeling is very strong and seems to label all membranous structures in the cells. It was possible to clearly distinguish differentially pre-labeled cells both in coculture and seeded on denaturated vascular grafts. The cells remain fluorescent for more than seven days and may be passaged with retained proliferative capability. We suggest that DiI/DiO-labeling using dye-containing medium may be used for several cell types and is applicable in tissue culture and in the detection of implanted cells in vivo.

Carbocyanines↗
PubMed1992

Serial cultivation of adult human endothelium from the great saphenous vein.

The growth of endothelial cells from small segments of human great saphenous vein was investigated for possible functional studies of endothelial cell properties and endothelialization of cardiovascular prosthetic graft materials. Growth in medium containing fetal calf serum or human serum was compared, and the effects of adding compounds that increase intracellular cyclic adenosine monophosphate levels, that is, cholera toxin and isobutylmethylxanthine, were also examined. It was shown that human serum was more efficient in stimulating cell growth than fetal calf serum at all concentrations tested. It was also shown that the addition of cholera toxin and isobutylmethylxanthine significantly potentiated growth. Minimal Essential Medium with the addition of 40% human serum and cholera toxin (1 nmol/L) and isobutylmethylxanthine (33 mumol/L) was shown to be optimal. From a single segment (3 to 5 cm), 20 x 10(6) human saphenous vein endothelial cells corresponding to 2000 cm2 or more could be achieved after 3 to 4 weeks in culture. The human saphenous vein endothelial cell cultures retained their cobblestone appearance, expression of von Willebrand Factor (vWF)-antigen, and capacity for prostacyclin production after six passages. We suggest that this provides a practically useful method for studies of cultured endothelium and possibly for pre-endothelialization of cardiovascular prosthetic materials.

1-Methyl-3-isobutylxanthine↗
PubMed1991

The effect of lidocaine on myocardial ischemia with asanguinous reperfusion. An in vitro study.

The effect of lidocaine on the ischemic nor-mothermic rat heart was studied in a Langendorff preparation. Ventricular fibrillation, total retrograde coronary flow and effluent lactate concentration were monitored in preischemia (control), ischemia (20 min) and reperfusion (20 min). Myocardial metabolites were determined in specimens excised at termination of reperfusion. Six hearts were infused with lidocaine in Ringer solution at onset of ischemia (group A) and six with only Ringer solution (group B). Sinus rhythm proceeded directly to diastolic arrest after 17 sec in group A, while all group B hearts showed ventricular fibrillation before arrest at 174 sec. Effluent lactate concentration was reduced in group A during the first 10 min of ischemia, but not subsequently. After 10 min of reperfusion, coronary flow was reduced by 12% in group A and 20% in group B. ATP was higher and ADP, AMP and IMP were lower in group A than in group B after 20 min of reperfusion. Creatine phosphate showed no intergroup difference, but creatine was higher in group B. Cardiac arrest with lidocaine thus reduced lactate formation during ischemia and lessened high-energy phosphate depletion after reperfusion.

Adenine Nucleotides↗
PubMed1991

Decreased liberation of noradrenaline from the heart following cold crystalloid cardioplegia.

Exogenous catecholamine support is often needed soon after termination of cardiopulmonary bypass even when appropriate cardioplegia has been used. To study the effect of hypothermic cardioplegic ischemia and reperfusion on the activity of the cardiac sympathetic nervous system, plasma noradrenaline concentration in the coronary sinus and general circulation was measured in six patients undergoing valve replacement for nonischemic mitral disease. Before cardiopulmonary bypass and cardioplegia the release of noradrenaline from the heart was greater than the mean systemic release. After ischemia, during reperfusion, the heart tended to extract noradrenaline, and 10 min after termination of bypass the plasma noradrenaline gradient over the heart remained less than pre-bypass. The results indicated decreased activity of the cardiac sympathetic nervous system, which may explain the frequent need for catecholamine support.

Cardiopulmonary Bypass↗
PubMed1990

Staphylococcus saprophyticus found to be a common contaminant of food.

The mode of transmission of Staphylococcus saprophyticus, a urinary tract pathogen, was investigated in three related studies. The presence of this organism was sought, during a period of 1 year, in 1331 specimens of various foods, in 920 beef and pork carcasses and on 107 cultures which had been inoculated directly from abattoir workers' protective gloves. Staphylococcus saprophyticus was found to contaminate 16.4% of the various food samples with a high prevalence of 34% in raw beef and pork. It was common in both domestic and imported raw meat products. There was no seasonal variation in the presence of S. saprophyticus in the samples obtained from carcasses. The bacterium was found in 69% of all cultures from the workers' protective gloves. We conclude that S. saprophyticus, originating from slaughtered animals, contaminates food and eventually colonizes the human intestinal tract.

Abattoirs↗
PubMed1990

Antihypertensive drugs and glucose metabolism: comparison between a diuretic, a beta-blocker and felodipine, a new calcium antagonist in subjects with arterial hypertension and diabetes.

Felodipine, a new antihypertensive calcium antagonist, was compared with metoprolol, a beta-blocker, and hydrochlorothiazide, a diuretic, with respect to glucose tolerance in a randomized double-blind cross-over study consisting of 11 patients, of age range 50-70 years, who had developed diabetes during antihypertensive treatment. Each treatment period lasted for 10 weeks. The blood pressure was similar irrespective of treatment. Serum glucose levels during the oral glucose tolerance test were significantly lower when the patients were treated with felodipine than when they were taking hydrochlorothiazide. Serum insulin levels appeared to decrease at an earlier stage of the test when the patients were treated with felodipine, the calcium antagonist, than with the other two antihypertensive substances, which suggests that glucose tolerance is impaired to a lesser extent during treatment with the calcium antagonist. Glucose tolerance was never completely normalized with any of the drugs tested.

Aged↗
PubMed1988

Acute atrophic glossitis after open-heart surgery.

The problem of Candida infections has become important in connection with transplant surgery and immunosuppression. To clarify the source of the postoperative acute atrophic glossitis (AAG) commonly seen in our department of cardiac surgery, 33 patients admitted for coronary artery bypass or valve replacement underwent clinical and microbiologic investigation before and after operation. None showed signs of AAG preoperatively, but 12 had cultures positive for Candida albicans, and in all 12 AAG appeared postoperatively. Six of the 21 patients with preoperatively negative cultures likewise had postoperative AAG. All 18 affected patients responded well to local nystatin treatment. No patient had disseminated candidiasis.

Acute Disease↗
PubMed1987

Inotropic effects of calcitonin gene-related peptide, vasoactive intestinal polypeptide and somatostatin on the human right atrium in vitro.

Inotropic responses to calcitonin gene-related peptide (alpha-CGRP), substance P, neurokinin A, capsaicin, neuropeptide Y, vasoactive intestinal polypeptide (VIP) and somatostatin (Som, 14 and 28 were analysed using the isolated, electrically driven auricle of the human right atrium. alpha-CGRP and VIP stimulated atrial contractility concentration dependently. alpha-CGRP was about 10-fold more potent than noradrenaline (NA) as an inotropic agent. Phentolamine plus metoprolol decreased the atrial response to NA significantly while the alpha-CGRP effect remained unchanged. Som did not influence the basal contractility of the atria, which, however, was inhibited by acetylcholine (ACh). ACh, Som 14 and Som 28 inhibited the NA-induced stimulation of atrial contractility, whereby Som 28 was more potent than Som 14. The inhibitory effects of ACh were completely blocked by atropine which did not influence the response to Som. Capsaicin, substance P, neurokinin A, neuropeptide Y (NPY) and the NPY fragments 1-19 and 26-36 did not induce any changes in contractility of the electrically driven human atrium. The present results suggest that some of the recently discovered neuropeptides (alpha-CGRP, VIP and Som) could be of importance in the regulation of cardiac contractility in man.

Acetylcholine↗