Biomedical subjects

T Lyberg

Publications and source records attributed to T Lyberg.

At least 91 records · Page 5Linked to original sources

PubMed1996

[Reconstruction of the jaw and oral cavity with free vascularized grafts].

59 microvascular graft transfers performed in 50 patients in our department since 1985 have been studied retrospectively. The indications for microvascular reconstruction were sequelae after tumour surgery in 38 patients, gunshot injury in seven, chronic osteomyelitis of the mandible in three, complication after jaw fracture in one patient, and atrophy of the alveolar ridge also in one patient. Transplants from the iliac crest, fibula, radius, radial forearm skin and jejunum were used. Three transplants were lost because of arterial thrombosis, giving a success rate of 94.9%. Complications were registered in 19 cases, the largest group being wound infections. 21 of the 50 patients have been treated with dental implants for total rehabilitation of masticatory function. Transfer of free vascularized bone and soft tissue grafts has greatly improved the functional and cosmetic results obtained in reconstructive surgery of the orofacial region.

Adolescent↗

PubMed1996

[Craniofacial surgery].

Craniofacial surgery is the term given to surgical techniques which allow combined access to the neurocranium and the facial skeleton. These techniques are applied primarily for treatment of fractures of the frontal/nasal/orbital regions, tumours of the orbits and the anterior cranial base, and congenital malformations, including simple or complex craniofacial synostoses, e.g. Crouzon and Apert syndromes. Indications for surgical treatment and the timing of the surgery are discussed. In addition, the most common surgical techniques are described and some clinical cases are presented.

Child, Preschool↗

PubMed1996

Morphologic and immunohistochemical observation of explanted Proplast-Teflon temporomandibular joint interpositional implants.

PURPOSE: The objective of this study was to investigate the cellular tissue response to temporomandibular joint (TMJ) Proplast-Teflon disc material by morphologic and immunohistochemical means. PATIENTS AND METHODS: Twelve patients who had been subjected to TMJ discectomy combined with insertion of a Proplast-Teflon interpositional implant (PTIPI) were recalled for removal of the alloplastic disc. The time elapsed between the Proplast-Teflon disc implantation and its removal varied between 13 and 71 months (mean, 54.6 +/- 5.8 [SEM]) The implants and periimplant tissues were examined by light microscopy and immunohistochemically using a panel of monoclonal antibodies reactive with different subclasses of leukocytes. The sections were immunostained using the alkaline phosphatase-antialkaline phosphatase (APAAP) technique. RESULTS: Fibrosis and a massive foreign body giant cell reaction were seen inside the heavily disrupted alloplastic implants and in the periimplant tissues. CD68-positive monocyte-derived cells dominated the reactive infiltrate in the implants and surrounding tissue. The CD68-positive cells also were partly positive for lysozyme. The lymphocytic infiltration contained no B cells. CONCLUSIONS: This study of the PTIPI-induced tissue reaction gave no indication of a toxic or an immunologic pathogenesis. Mechanical stress seems important in the fragmentation of the implant and induction of the foreign body reaction. It is not yet known if this fragmentation is the major contributing factor.

Adult↗

PubMed1996

Expression of beta-2-integrins and L-selectin by leukocytes and changes in acute-phase reactants in total hip replacement surgery.

The aim of this study was to characterize the changes in the quantitative expression of beta 2-integrins and L-selectin detected by means of fluorochrome-conjugated monoclonal antibodies and flow cytometry on leukocytes in the systemic circulation after a major musculoskeletal trauma, i.e. hip replacement surgery, and to relate these changes to parameters of the acute-phase response [plasma acute-phase reactants (C-reactive protein, CRP, and interleukin-6, IL-6) and parameters of coagulation activation (thrombin-antithrombin III complexes, TAT)]. Eight patients with either primary or secondary osteoarthritis of the hip received uncemented total hip prostheses. LFA-1 (CD11a/CD18) was upregulated on granulocytes during the operation. MAC-1 (CD11b/CD18) expression on monocytes increased to peak levels 20 h after surgery, whereas the L-selectin (CD62L) expression on monocytes and granulocytes reached peak values at the end of surgery. The changes in expression of LFA-1 on monocytes, MAC-1 on granulocytes and p150,95 (CD11c/CD18) on monocytes and granulocytes during and after the operation did not reach statistical significance. TAT and IL-6 increased during surgery and reached peak values at the end of the operation and 20 h after surgery, respectively. In contrast, CPR concentrations increased after surgery with peak levels 44 h postoperatively. Significant upregulation of LFA-1 on granulocytes and L-selectin on monocytes and granulocytes preceded the increase in IL-6 which again preceded the increase in CRP. However, the up- or downregulation of leukocyte beta 2-integrins and L-selectin during and after surgery was not significantly correlated with the increase in IL-6. The increases in TAT correlated well with the upregulation of L-selectin on monocytes, but not with the beta 2-integrins known to participate in the coagulation process in vitro. The rise in CRP was inversely correlated with the maximal increase in expression of MAC-1 on monocytes. In conclusion, the changes in leukocyte adhesion molecules during and after surgery indicate changes in critical leukocyte functions. The lack of correlation between quantitative up- and downregulation of leukocyte beta 2-integrins and parameters of the acute phase response suggests that these processes are regulated through independent pathways or that functional up- and downregulation of adhesion molecules, shedding, leukocyte-endothelial adhesion and mobilization of new unactivated cells may result in a net estimate of leukocyte activation not suspected to be positively correlated to acute-phase reactants.

Acute-Phase Proteins↗

PubMed1996

Interactions of endotoxin with human blood cells and serum proteins.

Endotoxin interacts with several plasma protein systems and blood cells, causing release of a multitude of endogenous mediators that contribute to the pathophysiological process of sepsis. Binding of 125I-labelled lipopolysaccharide, LPS, to human blood in vitro showed that the major part of the 125I-LPS was recovered in plasma, whereas only small amounts were retained in washed suspensions of granulocytes, erythrocytes, monocytes and lymphocytes, respectively. Whole leukocyte preparations or isolated subpopulations incubated with 125I-LPS or fluorescein-conjugated LPS followed by autoradiography, flow cytometry or immunofluorescence microscopy showed unequivocally that monocytes bound much more LPS than did granulocytes and lymphocytes. Lipoprotein electrophoresis followed by autoradiography showed that 125I-LPS bound to all the purified lipoprotein fractions, which was also confirmed by gel filtration chromatography. These findings demonstrate that monocytes represent the most important blood cell for LPS binding and that radiolabelled LPS is able to bind to lipoproteins as well as to other serum constituents.

Blood Proteins↗

PubMed1996

Different binding of 125I-LPS to plasma proteins from persons with high or low HDL.

In severe trauma, sepsis or during surgery, bacterial lipopolysaccharide (LPS) frequently enters the circulation. Persons with high levels of high-density lipoprotein (HDL) have previously demonstrated higher monocyte procoagulant activity (PCA) when whole blood is challenged with LPS. The aim of the study was to investigate the distribution of radiolabelled LPS (125I-LPS) in plasma from six persons with high (2.14-2.82 mmol l-1) and six persons with low (0.54-1.04 nmol l-1) HDL, subjecting plasma to fast protein liquid chromatography (FPLC), or agarose electrophoresis followed by quantitative autoradiography. In heparin plasma 125I-LPS was located mainly in parts of plasma containing low-density lipoprotein (LDL) or very low-density lipoprotein (VLDL) and the immunoglobulins, and located to a lesser extent in HDL. However, persons with high HDL showed significantly higher binding of 125I-LPS to HDL and the immunoglobulins, probably to IgG, and significantly lower binding to LDL/VLDL. In calcium-depleted plasma (EDTA) 125I-LPS demonstrated a sharp increase in the binding to HDL, combined with a persistently high binding to LDL/VLDL and binding to the immunoglobulins was almost eliminated in all subjects investigated. Likewise, the binding of 125I-LPS to HDL in EDTA plasma was also significantly higher and to LDL/VLDL significantly lower in persons with high HDL. This study demonstrates that the distribution of 125I-LPS in heparin and EDTA plasma from persons with high or low HDL is different, which is presumed to be of importance concerning the various bioactivities of LPS.

Autoradiography↗

PubMed1995

Increased activation of coagulation and formation of late deep venous thrombosis following discontinuation of thromboprophylaxis after hip replacement surgery.

Hip replacement surgery (HRS) is associated with a high frequency of deep vein thrombosis (DVT). At the same time there is a substantial systemic and local activation of coagulation. This study indicates that discontinuation of thromboprophylaxis one week after surgery may allow a second wave of coagulation and fibrinolysis activation to occur. An almost parallel increase in plasma TAT and D-dimer levels between the 6th and the 35th postoperative day may indicate late DVT formation. Repeated bilateral ascending venography is though to be necessary to evaluate the suitability of using selected activation markers of the coagulation and fibrinolytic systems as indices of DVT formation.

Aged↗

PubMed1995

Surgical treatment of internal derangement of the temporomandibular joint: long-term evaluation of three techniques.

PURPOSE: The long-term outcomes of three different surgical treatments for internal derangement of the temporomandibular joint (TMJ), ie, discoplasty, discectomy without replacement, and discectomy with replacement of the disc with a Proplast-Teflon (Vitek Inc, Houston, TX) interpositional implant (PTIPI) are compared. MATERIALS AND METHODS: Forty-two cases of internal derangement of the TMJ were treated with disc repair and eminectomy (group A, n = 13), simple discectomy (group B, n = 17) and discectomy combined with insertion of a PTIPI (group C, n = 12). Preoperative and postoperative findings (more than 5-year follow-up) relating to pain, mouth opening, joint noise, and radiographic changes were compared. RESULTS: Decrease of symptoms after surgery was reported by 77%, 94%, and 83% of the patients (groups A, B, and C, respectively). The decrease in pain intensity ranged from 52% to 71%. Mouth opening increased in 50% to 60% of the patients. The percentage increase ranged from 15% to 26% in the respective groups. Development of osteoarthrosis after surgery was demonstrated in 93% and 100% of the cases in the discectomy and discectomy/disc implant group, respectively, but only in 62% of the discoplasty group. CONCLUSION: This study demonstrates the importance of a functioning disc in the TMJ. There was no significant difference between the groups concerning symptoms before and after surgery. The discoplasty group, however, showed a high frequency of relapse, which necessitated secondary discectomy. PTIPIs clearly accelerated the development of osteoarthrosis, which may be classified as iatrogenic damage. The need for further research to establish the long-term performance of autogenous grafts and the development of improved alloplastic disc replacement materials is discussed.

Adult↗

PubMed1995

Obstructive sleep apnoea: a cephalometric study. Part I. Cervico-craniofacial skeletal morphology.

A comprehensive cephalometric analysis of cervico-craniofacial skeletal morphology in 100 male patients with obstructive sleep apnoea (OSA) and 36 male controls was performed. The significant aberrations in the OSA group feature: (1) shorter dimension of cranial base with slight counter-clockwise rotation and depression of clivus; (2) shorter maxillary length with normal height; (3) maxillo-mandibular retrognathia related to nasion perpendicular plane (N perpendicular FH) despite normal angles of prognathism; (4) 47 per cent of the OSA group had mandibular retrognathia; (5) increased anterior lower facial height and mandibular plane angle; (6) reduced size of bony pharynx; (7) inferiorly positioned hyoid bone at C4-C6 level; (8) deviated head posture with larger cranio-cervical angle. Cephalometric analysis is highly recommended in OSA patients as one of the most important tools in diagnosis and treatment planning.

Adult↗

PubMed1995

Obstructive sleep apnoea: a cephalometric study. Part II. Uvulo-glossopharyngeal morphology.

A comprehensive cephalometric analysis of uvulo-glossopharyngeal morphology in 100 patients with obstructive sleep apnoea (OSA) and 36 controls was performed. The aberrations in OSA patients included: 1. Increased length, thickness, and sagittal area of soft palate (PM-U; SPT; SPA: P < 0.001) with a more upright position (NL/PM-U: P < 0.05) and 15 per cent more pharyngeal area occupation [SPA/(OPA-OA): P < 0.001]. 2. The contact length between the soft palate and the tongue was increased approximately two-fold (CL: P < 0.001). 3. The sagittal area of the tongue was 10 per cent larger (TA: P < 0.001) despite similar length and height and 3 per cent more oral area occupation (TA/OA: P < 0.05). 4. More upright tongue position (VT/FH: P < 0.05) and caudally extended tongue mass (V perpendicular FH: P < 0.05). 5. Decreased sagittal dimensions of nasopharynx (pm-UPW: P < 0.001), velopharynx (U-MPW: P < 0.001) and minimum distance between the base of the tongue and the posterior pharyngeal wall (PASmin: P < 0.001). 6. The residual oropharyngeal area (area not occupied by soft tissues) was 9 per cent less due to larger tongue and soft palate [(TA+SPA)/OPA: P < 0.001]. Cephalometric analysis is highly recommended in OSA patients as one of the most important tools in diagnosis and treatment planning.

Adult↗

PubMed1995

The role of bone traumatization in the initiation of proximal deep vein thrombosis during cemented hip replacement surgery in pigs.

Hip arthroplasty is associated with a high frequency of postoperative solitary proximal deep vein thrombosis which seems most frequently observed when bone cement is used for prosthesis fixation. Eighteen pigs underwent hemiarthroplasty, eight with cement-fixed prostheses and eight with non-cement prosthesis installation. Levels of thrombin-antithrombin (TAT) complexes, tissue plasminogen activator (t-PA) activity and plasminogen activator inhibitor 1 (PAI-1) activity were determined in femoral vein blood from both limbs during and after surgery. On the operated side, TAT increased during bone traumatization followed by a substantial rise in t-PA activity and a gradual decline in PAI-1 activity. This indicates a local per- and post-operative sequential activation of coagulation and fibrinolysis followed by a fibrinolytic shutdown, all reflected in femoral vein blood on the operated side. In the animals receiving noncemented hip prostheses, the same pattern of activation of coagulation and fibrinolysis occurred on the operated side. This was, however, less marked than with the cement-fixed prostheses. Postoperative scanning electron microscopic (SEM) examination of the femoral veins showed thrombi on the operated side in 62% of the animals in the cement group and 25% in the non-cement group. In an additional study with eight animals undergoing cement-anchored hip prosthesis operations the levels of TAT, t-PA and PAI-I were analysed in femoral vein blood, mixed venous blood and arterial blood. Significantly higher levels were found in femoral vein blood compared with mixed venous blood while no significant change was found in arterial blood compared with mixed venous blood. The hyperthermia induced by curing bone cement was effectively conducted by the implanted prosthesis and did not seem to exert major influence on the activation of coagulation. Extreme rotation of the limbs during surgery did not in itself induce visible vein wall damage as judged by SEM. These studies indicate that traumatization of bone marrow during hip surgery induce a marked local activation of coagulation and a high incidence of deep vein thrombosis in proximal veins, in particular if bone cement is used for prosthesis fixation.

Animals↗

PubMed1995

Monitoring of tissue oxygenation in shock: an experimental study in pigs.

OBJECTIVE: To evaluate different methods and markers for assessing adequacy of tissue oxygenation in shock. DESIGN: Prospective, controlled animal trial. Two groups of six pigs, subjected to either a superior mesenteric artery occlusion shock or a hemorrhagic shock. A third group of five pigs served as controls. SETTING: Hospital animal research laboratory. SUBJECTS: Anesthetized, ventilated, juvenile, domestic pigs. INTERVENTIONS: Clamping of the superior mesenteric artery for 5 hrs, followed by reperfusion or withdrawal of blood to achieve a mean arterial pressure of 50 mm Hg for 3 hrs was performed, followed by resuscitation using the withdrawn whole blood. Invasive hemodynamic monitoring with arterial and pulmonary artery catheters was done. A tonometer was placed in the terminal ileum. MEASUREMENTS AND MAIN RESULTS: Ileal intramucosal pH, systemic base excess (or deficit), lactate concentration in systemic venous and arterial blood as well as in portal blood, ascitic fluid, and thoracic duct lymph, hemodynamics, and oxygen-related variables were measured. Five hours of intestinal ischemia caused no significant changes compared with the control group with regard to base excess or any of the hemodynamic or oxygen-related variables measured. However, lactate concentrations in the ascitic fluid and intramucosal pH were significantly altered within 1 hr of regional ischemia. Lactate concentration in the thoracic duct lymph was significantly increased after 2 hrs of ischemia, while lactate concentrations in the portal, systemic, and arterial blood were significantly increased after 2 hrs of regional ischemia. Reperfusion was associated with a high mortality rate, and only one animal survived the reperfusion period. In the hemorrhagic shock group, cardiac output and mean arterial pressure were significantly (intentionally) decreased 60 mins after the hemorrhage, while the heart rate, base excess, and systemic and portal blood lactate concentrations were significantly increased after 2 hrs of general hypoperfusion compared with those values in the control group. Ileal intramucosal pH, mixed venous oxygen saturation, oxygen delivery, oxygen extraction, and lactate concentrations in the arterial blood and thoracic duct lymph were significantly different from those values in the control group 3 hrs after the onset of hemorrhagic shock. Reperfusion induced a normalization of the hemodynamic and metabolic status of the animals. CONCLUSION: Many conventional markers of tissue hypoxia are useful when assessing general hypoperfusion, whereas intestinal intramucosal pH is the only reliable and clinically useful indicator of inadequate regional intestinal tissue oxygenation.

Animals↗

PubMed1995

Collagen-induced thrombus formation in flowing nonanticoagulated human blood from habitual smokers and nonsmoking patients with severe peripheral atherosclerotic disease.

The objective of the present study was to investigate collagen-induced platelet thrombus formation at arterial blood flow conditions in nonanticoagulated blood from habitual smokers and from nonsmoking patients with severe peripheral atherosclerotic disease. Collagen-induced thrombogenesis was elicited in native blood drawn directly from an antecubital vein over immobilized type III collagen fibrils coated on a coverslip positioned in a parallel-plate perfusion chamber. The wall shear rates at the collagen surface were comparable to those encountered in medium-sized (650 s-1) and moderately stenosed (2600 s-1) arteries. Thrombus formation in blood from habitual smokers after 10 hours of smoking abstinence appeared to be not different from thrombus formation in blood from healthy nonsmokers. However, immediately after a cigarette had been smoked, thrombus volume in blood from the same individuals was increased twofold at the highest shear rate (P < .05). Thus, the thrombotic response was temporarily upregulated after smoking. Thrombus formation in blood from nonsmoking patients with severe peripheral atherosclerotic disease was neither enhanced nor decreased but was within the range of the nonsmoking control subjects. However, fibrinopeptide A generation after 4 minutes of perfusion at 2600 s-1 was higher in blood from the atherosclerotic patients (P < .05) and associated with a higher plasma fibrinogen level (P < .005). Thus, signs of changed platelet reactivity in flowing nonanticoagulated blood were encountered only in the habitual smokers immediately after they had smoked a cigarette.

Adult↗

PubMed1995

Bile acids protect the liver against the cholestatic effect of large bilirubin loads.

BACKGROUND: This study was undertaken to elucidate why large bilirubin loads cause canalicular cholestasis and whether bile acid infusions protect against bilirubin-induced cholestasis. METHODS: The effects of bilirubin infusion on canalicular bile secretion and canalicular membrane morphology were studied in bile acid-depleted pigs (BADP), bile acid-primed pigs (BAPP), and pigs co-infused with bile acids during bilirubin loading (BACIP). RESULTS: Bilirubin caused complete cholestasis in BADP, 38% bile flow reduction in BAPP, and no effect on bile flow in BACIP. Scanning electron micrographs showed loss of 70% of canalicular microvilli in BADP, 13% loss and pathologic changes in the remaining 75% of microvilli in BAPP, and no canalicular changes in BACIP. Cholestasis was not due to hydromechanical obstruction of bile ductules or bile Ca2+ depletion. CONCLUSION: Bilirubin causes cholestasis in BADP by injuring canalicular microvilli. Intravenous glycocholate infusions fully protect the liver against bilirubin-induced cholestasis and canalicular microvillar injury.

Animals↗

PubMed1995

Endothelin and hemodynamic responses to superior mesenteric artery occlusion shock and hemorrhagic shock in pigs.

Endothelin is a novel, potent, endogenous vasoconstrictor derived predominantly from endothelium and macrophages. Release of endothelin-1 (ET-1) into biological fluids was determined by radioimmunoassay in pigs undergoing either a hemorrhagic (3 h) or superior mesenteric artery (SMA) occlusion (5 h) shock followed by reperfusion (90 min) or a control group which was observed for 8 h. After surgery, there was a significant increase in ET-1 in jugular and carotid plasma, lymph, and ascitic fluid in all three models. The portal plasma ET-1 level was significantly increased (p < .05, assessed by the Spearman rank coefficient rho) in both shock models, but no significant increase was noted in the control group. In the SMA occlusion shock model, four pigs died within 30 min of reperfusion, and these animals had a much higher level of portal ET-1 (22.3 +/- 5.5 fmol/mL) than the two pigs that were alive by the end of the observation period (11.5 +/- 1.3 fmol/mL). Reperfusion in the SMA occlusion shock model induced a critical form of circulatory shock characterized by hypotension, decreased cardiac output, and decreased left and right ventricular stroke work index, and death occurred usually within 90 min. Reperfusion of the shed blood in the hemorrhagic shock model almost normalized the hemodynamic derangements caused by the hypovolemia (with the exception of RVSWI), and the portal plasma and ascitic ET-1 levels decreased. These results indicate that ET-1 is released from the gut in response to both general hypoperfusion and selective intestinal ischemia and reperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Alterations in mucosal morphology and permeability, but no bacterial or endotoxin translocation takes place after intestinal ischemia and early reperfusion in pigs.

Ischemia and reperfusion of the gut may be an important etiological factor in the development of multiple organ failure. We have used a hemorrhagic and a superior mesenteric artery (SMA) occlusion shock model in pigs to estimate the effect of ischemia and reperfusion on intestinal morphology, mucosal permeability, and the occurrence of bacterial or endotoxin translocation. Mucosal ulceration and necrosis were found in the SMA shock model, while the morphological changes were less pronounced in the hemorrhagic shock model. Scanning electron microscopy showed shrinkage of the villi and plugging of the colonic crypts in both shock models. Enterocyte cell kinetics was investigated using 5-bromo-2'-deoksyuridine (BrdU) incorporation and immunovisualization by anti-BrdU antibodies. Cell renewal was almost completely lost from the jejunum to the rectum in both shock models. Intramucosal pH was measured using a tonometer placed in the terminal ileum. Segments of intestinal mucosa were mounted in Ussing chambers, and permeability was measured using radiolabeled probe molecules of differing molecular weights. Augmented molecular flux of inulin (M(r) 5.000) and mannitol (M(r) 182) and loss of short circuit current (Isc) and transepithelial potential difference (PD) were found in mucosae from both shock models. Endotoxin was demonstrated in the ascitic fluid in both shock models; 9.5 (2.7-14.3) (median and 95% confidence interval) EU/mL in the SMA occlusion model and 16.0 (4.9-29.4) EU/mL in the hemorrhagic shock model), but the levels were not significantly higher than in the control model 6.5 (4.3-34.0) EU/mL.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Effect of monomethylmethacrylate on procoagulant activities of human monocytes and umbilical vein endothelial cells in vitro.

Cemented total hip replacement surgery is associated with intraoperative cardiorespiratory depression and postoperative proximal deep vein thrombosis which may be linked to an extreme intraoperative thrombin generation and local and systemic effects of monomethylmethacrylate (MMA) released into circulation from curing cement. This in vitro study demonstrates that MMA alone or in combination with thrombin have effects on monocytes and human umbilical vein endothelial cells (HUVEC) which modulate their procoagulant activities. Moderate doses of MMA had a slight tissue factor (TF) inducing effect on monocytes. Small doses of MMA (0.1-1 mg/ml) [corrected] markedly potentiated the TF inducing effect of thrombin or lipopolysaccharide (LPS) which was included as a reference stimulant. These TF modulating effects of MMA were not seen with HUVEC. However, the generation of fibrinopeptide A (FPA) in cell overlay plasma indicated enhanced procoagulant activity of HUVEC treated with moderate doses of MMA, probably reflecting MMA cytotoxicity leading to cell retraction and exposure of extracellular matrix. Furthermore, small doses of MMA had a slight enhancing effect on FPA generation when coincubated with thrombin. These findings indicate that MMA in concentrations found in central venous blood in vivo, alone or together with thrombin, directly or indirectly exert effects that contribute to activation of coagulation.

Endothelium, Vascular↗

PubMed1994

Lipoproteins do not modulate the tissue factor activity, plasminogen activator or tumour necrosis factor production induced by lipopolysaccharide stimulation of human monocytes.

Upon stimulation with lipopolysaccharides (LPS), monocytes are able to produce tissue factor (TF), the most powerful physiological procoagulant substance known. In several assay systems LPS bound to lipoprotein has been reported to be less active than unbound LPS in stimulating monocytes. In the present study the LPS-induced TF activity was, however, not prevented by lipoproteins (VLDL, LDL, HDL). In fact, the very low density (VLDL) fraction further increased the TF inducing capacity of LPS. The lipoproteins per se mediated reduced plasminogen activator (PA) production in monocytes. LPS had an even more and significant depressing effect on PA production, which was not further decreased in the presence of lipoproteins. Furthermore, LPS-induced release of tumour necrosis factor (TNF), a marker of monocyte activity, was not inhibited by lipoproteins. Our experiments suggest that lipoproteins do not render LPS less effective in stimulating TNF release, procoagulant and fibrinolytic activities in human monocytes.

Cells, Cultured↗