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R Meyer

Publications and source records attributed to R Meyer.

At least 55 records · Page 3Linked to original sources
PubMed2001

Modulation of mouse neural crest cell motility by N-cadherin and connexin 43 gap junctions.

Connexin 43 (Cx43alpha1) gap junction has been shown to have an essential role in mediating functional coupling of neural crest cells and in modulating neural crest cell migration. Here, we showed that N-cadherin and wnt1 are required for efficient dye coupling but not for the expression of Cx43alpha1 gap junctions in neural crest cells. Cell motility was found to be altered in the N-cadherin-deficient neural crest cells, but the alterations were different from that elicited by Cx43alpha1 deficiency. In contrast, wnt1-deficient neural crest cells showed no discernible change in cell motility. These observations suggest that dye coupling may not be a good measure of gap junction communication relevant to motility. Alternatively, Cx43alpha1 may serve a novel function in motility. We observed that p120 catenin (p120ctn), an Armadillo protein known to modulate cell motility, is colocalized not only with N-cadherin but also with Cx43alpha1. Moreover, the subcellular distribution of p120ctn was altered with N-cadherin or Cx43alpha1 deficiency. Based on these findings, we propose a model in which Cx43alpha1 and N-cadherin may modulate neural crest cell motility by engaging in a dynamic cross-talk with the cell's locomotory apparatus through p120ctn signaling.

Animals↗
PubMed2001

Value of cardiac troponin I and T for selection of heart donors and as predictors of early graft failure.

BACKGROUND: Cardiac troponin I and T (cTnI and cTnT) are sensitive and specific markers of myocardial damage. We evaluated them for the selection of heart donors and as predictors of early graft failure after heart transplantation. METHODS: cTnI, cTnT, myoglobin, and creatine kinase (CK) levels and its isoenzyme MB (CKMB) activity and mass were measured in serum samples immediately before opening the pericardium from 126 consecutive brain-dead multi-organ donors over 10 years of age inspected by our harvesting team. Donors with serum creatinine >2.0 mg/dL (n=6) were excluded from the analysis. Donors for high-urgency status recipients (n=2) were also excluded. The remaining donors were retrospectively divided into three groups: group I (n=68), grafts with good function; group II (n=11), grafts with impaired function; and group III (n=39), grafts not accepted for transplantation. RESULTS: No differences in donor and recipient characteristics were found among the groups. The mean values of cTnI (0.36+/-0.88 microg/L, 4.45+/-3.28 microg/L, and 3.02+/-7.88 micog/L, respectively) and cTnT (0.016+/-0.029 microg/L, 0.134+/-0.114 microg/L, and 0.123+/-0.245 microg/L, respectively) were lower in group I when compared with groups II or III (cTnI: P<0.0001, P=0.018; cTnT: P<0.0001, P=0.012). The cTnI value was higher in group II compared with group III (P=0.023). The cTnT values were similar in groups II and III. A cTnI value >1.6 microg/L as a predictor of early graft failure had a specificity of 94%, and a cTnT value of >0.1 microg/L had a specificity of 99%. The odds ratio for the development of acute graft failure after heart transplantation was 42.7 for donors with cTnI >1.6 microg/L and 56.9 for donors with cTnT >0.1 microg/L. No differences of myoglobin, CKMB activity, or CKMB/CK ratio were found among the groups. CONCLUSIONS: Significantly higher cTnI and cTnT values were found in peripheral blood at the time of explantation in donors of hearts with subsequently impaired graft function and in not accepted donors. cTnI and cTnT are useful as additional parameters for heart donor selection.

Adult↗
PubMed2001

Behavioural problems in children who weigh 1000 g or less at birth in four countries.

BACKGROUND: The increased survival chances of extremely low-birthweight (ELBW) infants (weighing <1000 g at birth) has led to concern about their behavioural outcome in childhood. In reports from several countries with different assessments at various ages, investigators have noted a higher frequency of behavioural problems in such infants, but cross-cultural comparisons are lacking. Our aim was to compare behavioural problems in ELBW children of similar ages from four countries. METHODS: We prospectively studied 408 ELBW children aged 8-10 years, whose parents completed the child behaviour checklist. The children came from the Netherlands, Germany, Canada, and USA. The checklist provides a total problem score consisting of eight narrow-band scales. Of these, two (aggressive and delinquent behaviour) give a broad-band externalising score, three (anxious, somatic, and withdrawn behaviour) give a broad-band internalising score, and three (social, thought, and attention problems) indicate difficulties fitting neither broad-band dimension. For each cohort we analysed scores in ELBW children and those in normal- birthweight controls (two cohorts) or national normative controls (two cohorts). Across countries, we assessed deviations of the ELBW children from normative or control groups. FINDINGS: ELBW children had higher total problem scores than normative or control children, but this increase was only significant in European countries. Narrow-band scores were raised only for the social, thought, and attention difficulty scales, which were 0.5-1.2 SD higher in ELBW children than in others. Except for the increase in internalising scores recorded for one cohort, ELBW children did not differ from normative or control children on internalising or externalising scales. INTERPRETATION: Despite cultural differences, types of behavioural problems seen in ELBW children were very similar in the four countries. This finding suggests that biological mechanisms contribute to behavioural problems of ELBW children.

Canada↗
PubMed2001

Reduction of potassium currents and phosphatidylinositol 3-kinase-dependent AKT phosphorylation by tumor necrosis factor-(alpha) rescues axotomized retinal ganglion cells from retrograde cell death in vivo.

Tumor-necrosis-factor-alpha (TNF-alpha) prevented secondary death of retinal ganglion cells (RGCs) after axotomy of the optic nerve in vivo. This RGC rescue was confirmed in vitro in a mixed retinal culture model. In accordance with our previous findings, TNF-alpha decreased outward potassium currents in RGCs. Antagonism of the TNF-alpha-induced decrease in outward potassium currents with the potassium channel opener minoxidilsulfate (as verified by electrophysiology) abolished neuroprotection. Western blot analysis revealed an upregulation of phospho-Akt as a consequence of TNF-alpha-induced potassium current reduction. Inhibition of the phosphatidylinositol 3-kinase-Akt pathway with wortmannin decreased TNF-alpha-promoted RGC survival. These data point to a functionally relevant cytokine-dependent neuroprotective signaling cascade in adult CNS neurons.

Animals↗
PubMed2001

CD34-positive acute promyelocytic leukemia is associated with leukocytosis, microgranular/hypogranular morphology, expression of CD2 and bcr3 isoform.

Acute promyelocytic leukemia (APL) has a favorable prognosis. Current therapy includes chemotherapy used in combination with all-trans-retinoic acid (ATRA). Although the differentiating effects of ATRA on promyelocytes have been well established, in vitro studies have shown that less-differentiated APL blasts (CD34(+)) demonstrate a variable responsiveness to ATRA. To assess the clinical relevance of this finding, we analyzed a cohort of 38 patients with t(15;17) and/or PML-RARalpha APL to determine the incidence and laboratory features of CD34(+) APL. Thirty-two percent (12/38) of cases were CD34(+). There was a difference in WBC at presentation between CD34(+) and CD34(-) cases (34.6 +/- 9.2, mean +/- standard error vs. 5.4 +/- 2.0, P = 0.009). Patients with CD34(+) APL demonstrated a micro/hypogranular phenotype (75%) (P = 0.001), co-expression of CD2(+) (83%) (P = 0.001), and the bcr3 isoform (100%) (P = 0.017). In contrast, CD34(-) cases demonstrated hypergranular morphology (65%), CD2(+) (15%), and the bcr1 isoform (50%). A high presenting WBC count (\G10 x 10(9)/L) was associated with an inferior overall survival (Log rank = 0.0047). Patients with CD34(+) APL demonstrated an incidence of early mortality of 50%. Despite a marked correlation between CD34 positivity and increased WBC count, overall survival of CD34(+) and CD34(-) cases did not differ significantly in our small cohort. Immunophenotypic analysis for CD34 expression should be included in future large APL trials to determine if detection of CD34(+) blasts represents an independent adverse prognostic factor.

Actuarial Analysis↗
PubMed2001

New pulsatile bioreactor for fabrication of tissue-engineered patches.

To date, one approach to tissue engineering has been to develop in vitro conditions to ultimately fabricate functional cardiovascular structures prior to final implantation. In our current experiment, we developed a new pulsatile flow system that provides biochemical and biomechanical signals to regulate autologous patch-tissue development in vitro. The newly developed patch bioreactor is made of Plexiglas and is completely transparent (Mediport Kardiotechnik, Berlin). The bioreactor is connected to an air-driven respirator pump, and the cell culture medium continuously circulates through a closed-loop system. We thus developed a closed-loop, perfused bioreactor for long-term patch-tissue conditioning, which combines continuous, pulsatile perfusion and mechanical stimulation by periodically stretching the tissue-engineered patch constructs. By adjusting the stroke volume, the stroke rate, and the inspiration/expiration time of the ventilator, it allows various pulsatile flows and different levels of pressure. The whole system is a highly isolated cell culture setting, which provides a high level of sterility, gas supply, and fits into a standard humidified incubator. The bioreactor can be sterilized by ethylene oxide and assembled with a standard screwdriver. Our newly developed bioreactor provides optimal biomechanical and biodynamical stimuli for controlled tissue development and in vitro conditioning of an autologous tissue-engineered patch.

Biocompatible Materials↗
PubMed2001

Food chain aspects of chlordane poisoning in birds and bats.

We have observed recurring chlordane poisonings of large numbers of common grackles (Quiscalus quiscula), European starlings (Sturnus vulgaris), and American robins (Turdus migratorius) at suburban roosts in New Jersey during the month of July. This paper describes aspects of the food chain uptake of chlordane that account for the periodicity of these poisonings. Chlordane concentrations ranged from < 0.02 to 20.3 microg/g wet weight in 11 soil samples collected from residential lawns and a golf course near one roost. Of the 10 species of insects and soil invertebrates collected from the area, two scarab beetles, the oriental beetle (Anomala orientalis) and Japanese beetle (Popilla japonica), had the highest concentrations of chlordane-related compounds (15.1 and 5.9 microg/g wet weight, respectively). Concentrations in the other eight species ranged from < 0.04 to 1.3 microg/g. Oriental and Japanese beetles collected from a rural location had concentrations of 0.03 and < 0.02 microg/g, respectively. Emergence of adult beetles peaked in mid- to late July, when bird mortality also peaked. Fecal pellets collected near the roost (n = 24) contained the remains of 1-5 beetles each (mean = 2), and scarab beetles accounted for 40% of the total number of insect parts in the stomach contents of common grackles (n = 8). Unlike soil samples, in which cis- and trans-chlordane predominated, beetles contained large amounts of the more toxic metabolites heptachlor epoxide and oxychlordane. Total chlordane-related compounds ranged from < 0.05 to 18.4 microg/g in Japanese beetles collected from 16 sites in New Jersey and 2 sites in Ohio. The highest concentrations were found in beetles from suburban areas and golf courses. We also analyzed brain tissue from insectivorous bats (15 big brown bats, Eptesicus fuscus, and 5 little brown bats, Myotis lucifugus) that were submitted to the New Jersey Rabies Laboratory in late June/July 1998 and 1999 but found to be rabies-negative. We suggest that high concentrations in three of the bats caused debility or abnormal behavior that may have precipitated submission for rabies testing.

Animals↗
PubMed2001

Comparison of antimicrobial use and resistance of bacterial isolates in a haematology ward and an intensive care unit.

The objective of the study presented here was to compare antimicrobial use and resistance of bacterial isolates in the haematology ward and the intensive care unit of Bolzano General Hospital. The bacterial organisms isolated most frequently from patients in the two wards (coagulase-negative staphylococci, Enterococcus spp., and Pseudomonas aeruginosa) were investigated for antimicrobial resistance. Isolates obtained from patients in the haematology ward were more often resistant to antimicrobial agents than isolates obtained from patients in the intensive care unit, and the agents against which the highest rates of resistance were found were third- and fourth-generation cephalosporins, carbapenems and monobactams, quinolones, aminoglycosides, and trimethoprim-sulfamethoxazole. These classes of antimicrobial agents were also used more frequently in the haematology ward than in the intensive care unit. Conversely, penicillinic beta-lactam antibiotics, rifamycins, macrolides and lincosamides were used less frequently in the haematology ward than in the intensive care unit, and the rates of resistance against these classes of antimicrobial agents were significantly lower in the haematology ward than in the intensive care unit. The results support the hypothesis that a causal relationship exists between antimicrobial use and the development of resistance and indicate that careful monitoring of antimicrobial use in hospitals is required to identify situations in which prescription patterns are contributing to the development of resistance.

Anti-Bacterial Agents↗
PubMed2001

Bridging-to-recovery.

BACKGROUND: Patients with end-stage heart failure placed on a cardiac assist device show at least some degree of improvement of cardiac function. In a subgroup of selected patients, some hearts recovered considerable function. In these patients the device was removed and cardiac transplantation was no longer necessary. We report our long-term experience with these weaned patients. METHODS: As of today, 512 cardiac assist devices of various types (Berlin Heart, Berlin, Germany; Novacor, World Heart, Ottawa, Ontario, Canada; TCI, ThermoCardio Systems, Inc, Woburn, MA; DeBakey, Micromed Technology Inc, Houston, TX) were implanted in patients with end-stage heart failure in our institution. Of these, 95 patients belonged to a subgroup of patients with nonischemic, idiopathic, dilated cardiomyopathy who were implanted with a left ventricular support system (Novacor 84, TCI 10, Berlin Heart 1) between 1994 and 2000. All were routinely examined by echocardiography for improvement of cardiac function. The left ventricular diameter in diastole (LVIDd) and left ventricular ejection fraction (LVEF) served as the main parameters to assess changes in cardiac performance. Under the conditions of a running device, an LVIDd below 60 mm and an LVEF above 40% were the criteria to do further echocardiographic studies when the pump was turned off for up to 20 minutes. RESULTS: Twenty-eight patients (26 men, 2 women; ages 18 to 64 yrs; history of heart failure, 1 to 17 yrs) fulfilled the criteria of improved cardiac performance and were weaned from the device. Since then, 16 patients have continued "normal" heart function with follow-up times ranging from 1 month to 5.5 years (group B). Three patients died of noncardiac causes (group C). Eight patients were transplanted from 1 to 17 months later and one died on the waiting list (group A). Statistically significant differences between groups A and B were calculated for the duration of heart failure (9 versus 2 years, p = 0.0002). Differences in LVIDd before removal of the device (57 versus 51 mm, p = 0.0420), LVEF after 2 months of unloading (30 versus 49%, p = 0.0300), and LVEF preexplantation (43 versus 52%, p = 0.0001) were significant. Overall, 17% of the cohort of 95 patients were weaned successfully. CONCLUSIONS: Weaning from cardiac assist devices is feasible for selected patients; it saves donor hearts and is preferred to cardiac transplantation. However, as of today no reliable parameter predicts outcome after weaning and none determines the possibility of device removal before implantation in advance.

Adolescent↗
PubMed2001

Primary cardiac tumours: when is surgery necessary?

OBJECTIVE: Primary cardiac tumours are rare. The literature predominantly contains series on myxomas in adults and only a few long-term series that involve the very different primary cardiac tumours in early childhood. As foetal ultrasonography has continued to improve, cardiac tumours are increasingly detected early before significant symptoms develop. It is a challenge for paediatric cardiologists and surgeons to ascertain which patients need surgery and which will benefit from conservative follow-up. METHODS: A retrospective review of a 10-year period revealed 51 tumours in 26 children (median age: 1 month). Analysis was by presentation, location, associated findings, interventions, histological findings, and clinical course. RESULTS: The most common tumours were rhabdomyomas (29), fibromas (nine), teratomas (two), and haemangiomas (two). The tumour location was the right ventricle in 24 and the left ventricle in 22 patients. The symptoms varied between abnormal heart murmur (20), arrhythmia and conduction abnormalities (ten), obstruction of the outflow tract >30 mmHg (nine), severe cyanosis (three) and congestive heart failure (two). Fourteen children with haemodynamic compromises underwent surgery. There was one post-operative death and one heart transplantation after bridging with an assist device. There was no tumour recurrence even when resection was incomplete. Nine of 13 children with rhabdomyomas had spontaneous tumour regression without intervention. CONCLUSIONS: Most of the cardiac tumours in children are benign. Spontaneous regression is possible not only in rhabdomyoma. Surgical intervention is only required for children who develop relevant clinical symptoms. Total resection of the tumour is not the only therapeutic aim; more important is the restoration of the best possible heart function.

Adolescent↗
PubMed2001

Molecular structure and activity toward DNA of baicalein, a flavone constituent of the Asian herbal medicine "Sho-saiko-to".

Baicalein (5,6,7-trihydroxyflavone, 1) is of interest because of its broad spectrum of biological activity. It is a constituent of the east Asian herbal remedy, "Sho-saiko-to". The 3D structure of 1 was determined using X-ray diffraction. The compound exists in an almost planar conformation with a C-2-C-1' bond distance of 1.476(5) A. Hydrogen-bonding interactions predominate in the crystal structure. The position of the three hydroxyl groups maximizes intramolecular hydrogen bonding, and each of the hydroxyl hydrogen atoms is a donor in a three-center hydrogen bond. The carbonyl oxygen, O-4, is an acceptor in an intramolecular hydrogen bond (with OH-5). Two molecules of 1 exist as hydrogen-bonded dimers related by inversion center (-x + 1, -y, -z + 1). O-4 is also an acceptor in an intermolecular hydrogen bond with OH-6. The planarity of the flavone framework is dependent on structural and/or electronic forces that stabilize the negative charge on the exocyclic oxygen atom, O-4. Compound 1, therefore, is planar in any situation where forces can stabilize the negative charge on O-4. Consistent with this, UV absorbance studies performed on 1-DNA complexes with varying concentrations of 1 strongly suggest intercalation of 1 within the double helix, followed by possible interstrand cross-links.

Animals↗
PubMed2001

Hantavirus pulmonary syndrome in the State of São Paulo, Brazil, 1993-1998.

Between 1993 and 1998, 10 cases of clinical hantavirus infection were diagnosed in Brazil. Hantavirus-specific IgM, or positive immunohistochemical analysis for hantavirus antigen, or positive reverse transcription-polymerase chain reaction results for hantavirus RNA were used to confirm nine of these cases; eight were hantavirus pulmonary syndrome (HPS), and one was mild hantavirus disease. The remaining clinical case of hantavirus infection was fatal, and no tissue was available to confirm the diagnosis. During the first 7 months of 1998, five fatal HPS cases caused by a Sin Nombre-like virus were reported from three different regions in the State of São Paulo, Brazil: two in March (Presidente Prudente Region), two in May (Ribeirão Preto Region), and one in July (Itapecerica da Serra Region). Epidemiologic, ecologic, and serologic surveys were conducted among case contacts, area residents, and captured rodents in five locations within the State of São Paulo in June of 1998. Six (4.8%) of 125 case contacts and six (5.2%) of 116 area residents had IgG antibody to Sin Nombre virus (SNV) antigen. No case contacts had a history of HPS-compatible illness, and only one area resident reported a previous acute respiratory illness. A total of 403 rodents were captured during 9 nights of trapping (1969 trap nights). All 27 rodents that were found to be positive for IgG antibody to SNV antigen were captured in crop border and extensively deforested agricultural areas where four of the 1998 HPS case-patients had recently worked. The IgG antibody prevalence data for rodents suggest that Bolomys lasiurus and perhaps Akodon sp. are potential hantavirus reservoirs in this state of Brazil.

Adolescent↗
PubMed2001

Somatotopic organization of human secondary somatosensory cortex.

This fMRI study investigated the human somatosensory system, especially the secondary somatosensory cortex (SII), with respect to its potential somatotopic organization. Eight subjects received electrical stimulation on their right second finger, fifth finger and hallux. Within SII, the typical finding for both fingers was a representation site within the contralateral parietal operculum roughly halfway between the lip of the lateral sulcus and its fundus, whereas the representation site of the hallux was found more medially to this position at the fundus of the lateral sulcus, near the posterior pole of the insula. Somatotopy in SII seems to be less fine-grained than in primary somatosensory cortex (SI), as, in contrast to SI, no separate representations of the two fingers in SII were observed. A similar somatotopic representation pattern between fingers and the hallux was also observed within ipsilateral SII, indicating somatotopy of contra- as well as ipsilateral SII using unilateral stimulation. Further areas exhibiting activation were found in the superior and inferior parietal lobule, in the supplementary and cingulate motor area, and in the insula.

Adult↗
PubMed2001

Pre-focused lead titanate > 25 MHz single-element transducers from hollow spheres.

Miniature lead titanate (PT) hollow spheres with diameters in the 1 to 10 mm range and wall thicknesses of 20 to 120 microns have been fabricated. Shell sections were used as components of pre-focused transducers. Spheres are produced using a new sacrificial core technique that produces hundreds of spheres with a more uniform wall thickness than those produced by earlier methods. Shells produced from these spheres were found to have a wall thickness variation of about 10%. Despite this variation, bulk properties were estimated from capacitance and impedance data. Shells tested in this work had dielectric constants (1 kHz) near 280 with loss factor of < 2% and d33 values of 68 pC/N. Thickness coupling coefficients averaged 0.51 with mechanical quality factors of < 15. A transducer fabricated from these sections of spheres had a round-trip insertion loss of -20.1 dB at the center frequency of 39.8 MHz and a 6 dB bandwidth of 33%.

Biomedical Engineering↗
PubMed2001

N-cadherin and Cx43alpha1 gap junctions modulates mouse neural crest cell motility via distinct pathways.

Our previous studies showed an essential role for connexin 43 or alpha1 connexin (Cx43alpha1) gap junctions in the modulation of neural crest cell motility. Cx43alpha1 gap junctions and N-cadherin containing adherens junctions are expressed in migrating cardiac neural crest cells. Analysis of the N-cadherin knockout (KO) mouse model revealed that N-cadherin is essential for gap junction mediated dye coupling but not for expression of Cx43alpha1 gap junctions in neural crest cells. Time lapse videomicroscopy and motion analysis showed that the motility of N-cadherin KO neural crest cells were altered, but the motility changes differed compared to Cx43alpha1 KO neural crest cells. These observations suggest that the role of N-cadherin in cell motility is not simply mediated via the modulation of Cx43alpha1 mediated cell-cell communication. This was confirmed by a parallel analysis of wnt-1 deficient neural crest cells, which also showed a reduction in dye coupling, and yet no change in cell motility. Analysis of p120 catenin (p120ctn), an Amardillo family protein known to play a role in cell motility, showed that it is colocalized with N-cadherin and Cx43alpha1 in migrating neural crest cells. This subcellular distribution was altered in the N-cadherin and Cx43alpha1 KO neural crest cells. Given these results, we propose that N-cadherin and Cx43alpha1 may modulate neural crest cell motility by engaging in a dynamic cross-talk with the cell's locomotory apparatus through p120ctn signaling.

Animals↗
PubMed2001

Antimicrobial use and susceptibility rates in isolates from intensive care unit and other nosocomial inpatient and outpatient areas.

Our objective was to evaluate the relation between antimicrobial use and susceptibility in the intensive care unit (ICU) and non-ICU inpatient areas in the Bolzano regional hospital. For the isolates of S. aureus, coagulase negative staphylococci, Enterococcus sp., P. aeruginosa and E. coli we found a pattern of significant stepwise decrease in the frequency of antimicrobial susceptibility to penicilloic beta-lactam antibiotics and first generation cephalosporins; the highest senitivity rates occurred among isolates from outpatients, followed in decreasing order by rates among isolates from non-ICU inpatients and from ICU-patients; the rate of use of this group of antimicrobial agents was relatively high in the intensive care unit (13,1%). For P. aeruginosa we observed significantly lower susceptibility-rates to second, third and fourth generation cephalosporins, carbapenems and monobactams for non-ICU inpatient areas than for outpatient or ICU areas; this paralleled with the low use of this group of agents in the ICU area (4,9%). Also, for P. aeruginosa the prevalence of susceptibility to ciprofloxacin and norfloxacin in inpatient areas was lower than in the outpatient or ICU-areas; the rate of quinolone-use was relatively low in the ICU area (4,2%).

Ambulatory Care Facilities↗
PubMed2001

Endothelialization of PTFE vascular grafts under flow induces significant cell changes.

BACKGROUND: To minimize thrombogeneity of small diameter PTFE grafts they are usually coated in vitro with endothelial cells under static culture conditions. The disadvantage of this technique is that a cell layer is formed that fails to withstand shear stress typical in normal blood flow. METHOD: Since the in vivo functional and structural status of endothelial cells correlates with the applied shear stress, we developed a computer-controlled perfusion system to seed and culture cells on PTFE-grafts up to a confluent monolayer under the influence of increasing shear stress. The confluence of endothelial coating was defined by immunohistological staining of cross sections, and by upper light microscopy of flattened graft samples. In addition, the expression of fibronectin as an important adhesion molecule was estimated. RESULTS AND DISCUSSION: The application of pulsatile shear stress (6.6 dyn/cm2, 5 min) to grafts endothelialized under perfusion (n = 7) did not lead to a disruption of the confluent cell layer. In contrast, a 5 min long shear stress of 3 dyn/cm2 was sufficient to wash more than 50% of cells off the PTFE-graft cultured under static conditions (n = 6). The perfusion cultures showed a significantly higher proliferation rate in comparison with static cultures. This effect was reproducibile in both serum-containing and serum-free culture media. The expression of fibronectin by endothelial cells was significantly higher in the perfused graft compared to the static one. These results suggest the practicability of endothelialized PTFE vascular grafts, preconditioned to shear rates similar to the in vivo situation, as an alternative bypass material in cardiac surgery.

Blood Vessel Prosthesis↗