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Biomedical subjects

G Printzen

Publications and source records attributed to G Printzen.

At least 19 recordsLinked to original sources
PubMed2004

[Influence of local application of basic fibroblast growth factor on resistance to local infection after standardized closed soft tissue trauma. An experimental study in rats].

The aim of the study was to obtain information on the importance/influence of local application of an angiogenic potent growth factor (bFGF) on local infection resistance after soft tissue trauma.A paired comparison of infection rates was carried out on Sprague-Dawley rats after standardized, closed soft tissue trauma and local, percutaneous bacterial inoculation of different concentrations (2 x 10(4)-2 x 10(7)), whereby the lower leg was treated with 1, 10, and 100 ng bFGF (n=16 each) and without bFGF (n=16). Statistical evaluation of the differences between the infection rates of both groups was performed using the two-sided Fisher's exact test ( p<0.05). For the group without bFGF application, the infection rate was 25%. In the groups with 1, 10, and 100 ng bFGF application, the infection rates were 50%, 69%, and 81%. The difference in the infection rates for the groups in which 10 and 100 ng bFGF were applied was highly significant ( p=0.032/ p=0.004) compared with the group without bFGF. If these initial results are confirmed for other angiogenic potent growth factors, then the local application of growth factors to stimulate wound and bone healing will need to be reconsidered and preceded by a very strict evaluation of the risks and benefits.

Animals↗
PubMed2001

Polylactide implants and bacterial contamination: an animal study.

Although bioresorbable aliphatic polyesters derived from lactic acid are now used clinically as sutures, bone-fracture fixation devices and sustained-release drug-delivery systems, very little is known about their behavior in the infected environment. The aim of the present study was to compare the resistance to infection of two polylactide implants with different degradation characteristics, and to evaluate the influence of a bacterial challenge on their mechanical and physicochemical properties. Various quantities of a beta-haemolyzing strain of Staphylococus aureus (V 8189-94) were inoculated into the medullary cavity of rabbit tibiae, and an extruded polylactide rod composed of either P(L)LA (Poly(L-Lactide)) or P(L/DL)LA (Poly(L/DL-Lactide)) was then inserted. Animals were sacrificed four weeks after surgery. The tibiae and implants were removed under sterile conditions and evaluated microbiologically by culturing. The severity of infection was graded according to positive colony-forming units in the bone. The mechanical properties of the retrieved implants were assessed by 4-point bending and shear tests, performed in compliance with the ASTM D790 standard and their physicochemical characteristics also were characterized. P(L)LA and P(L/DL)LA implants were equally resistant to local infection, their mechanical and physicochemical properties being unaffected by bacterial challenge. Hence, once an infection has become established, the release of bactericidal/bacteriostatic by-products during implant degradation does not appear to affect its natural course. The release of bactericidal/bacteriostatic degradation products at the implantation site is unlikely to affect the natural course of an established infection.

Animals↗
PubMed2001

PC-Fix and local infection resistance--influence of implant design on postoperative infection development, clinical and experimental results.

Bacterial infection is still one of the main complications after internal fixation of fractures. The design of implants influences local infection resistance. To reduce the development of infections around implants after internal fixation, the vitality of the bone should be preserved to optimize cellular and humoral host defence mechanisms. For extramedullary fracture fixation, two implant designs are currently in routine use: the Dynamic Compression Plate (DCP) and the Limited Contact Dynamic Compression Plate (LC-DCP). The Point-Contact-Fixator (PC-Fix) is a new design concept based on the philosophy of the LC-DCP and the external fixator. Its function relies on splinting the fragments of a fracture internally with locking bolts rather than with screws that compress the plate to the bone. In this way, the blood supply is not compromised by compression of the periosteum. We investigated the effect of this new design on the incidence of postoperative infection rates in a clinical and an experimental setting. In a prospective multicentre study 1,229 PC-Fixators were used in 896 patients. Of these, 1,172 were available for assessment of infection development. The overall infection rate was 1.1% (13/1,172). The infection rate after open fractures was 1.6% (4/256) and after closed procedures (including closed fractures, osteotomies and non-unions) 1.0% (9/916). These rates are low in comparison to published rates using DCP and LC-DCP. In an experimental study, we compared the infection rates across two groups of rabbits four weeks after fixing either a bacterially contaminated DCP or a PC-Fix to the tibia. Infection rates in the DCP group were significantly higher than in the PC-Fix group: Of the 38 evaluated animals, 12 with a DCP and 5 with a PC-Fix developed local infection (p=0.022). The new PC-Fix design shows low postoperative infection rates in the clinical setting and lower infection rates than the DCP in the experimental setting. The design is an important step in the process of reducing postoperative infection rates.

Adolescent↗
PubMed2001

Ischaemia/reperfusion contributes to colonic injury following experimental aortic surgery.

OBJECTIVES: ischaemia of the colon is an important complication of abdominal aortic aneurysm (AAA) repair. The aim of this animal study was to investigate the effect of sequential ischaemia and reperfusion on sigmoid mucosal pO2 and its association with local ET-1 release. MATERIAL AND METHODS: twelve pigs underwent colonic ischaemia followed by complete reperfusion. Six other animals were sham controls. A Clark-type microcatheter was used for continuous mucosal pO2 measurements. Serial systemic and inferior mesenteric vein blood samples were obtained for determination of ET-1 concentration. Neutrophil extravasation was assessed by tissue myeloperoxidase (MPO) activity. RESULTS: arterial occlusion was associated with a gradual decrease of mucosal pO2 and local release of ET-1. After restoration of blood flow, mucosal pO2 returned to near baseline values, whereas ET-1 reached its maximum concentration during the reperfusion period. MPO activity was significantly increased. CONCLUSIONS: colonic ischaemia and reperfusion causes neutrophil extravasation and local ET-1.

Animals↗
PubMed2000

Antioxidant and thyroid hormone status in selenium-deficient phenylketonuric and hyperphenylalaninemic patients.

BACKGROUND: Subjects consuming protein-restricted diets, such as patients with phenylketonuria (PKU) or milder hyperphenylalaninemias (HPAs) are at risk of selenium deficiency. Selenium is a cofactor of the antioxidant enzyme glutathione peroxidase and of the thyroid hormone converting enzyme thyroxine deiodinase. OBJECTIVE: Our goal was to investigate the effects of low plasma selenium on antioxidant and thyroid hormone status. DESIGN: We assessed plasma selenium, plasma total antioxidant status and the individual components thereof, erythrocyte antioxidant status, and plasma thyroid hormones in 24 PKU and 10 HPA patients and in 42 age-matched control subjects. RESULTS: Selenium was significantly lower in both PKU and HPA patients than in control subjects and the PKU patients had lower values than did the HPA patients. Total antioxidant status was lower in both patient groups than in the control group, whereas alpha-tocopherol, albumin, and uric acid were not significantly different among groups. Plasma selenium correlated well (r = 0.76) with erythrocyte glutathione peroxidase. PKU patients had lower glutathione peroxidase activity than did HPA patients and control subjects and lower glutathione concentrations than did control subjects. Both patient groups had lower superoxide dismutase activity than did control subjects. Free triiodothyronine was higher in both patient groups than in control subjects, whereas free thyroxine was higher in the PKU patients only. Free thyroxine and reverse triiodothyronine were inversely correlated with selenium. CONCLUSION: Supplementation with selenium seems to be advisable for patients consuming diets low in natural protein.

Adolescent↗
PubMed2000

Role of procalcitonin and granulocyte colony stimulating factor in the early prediction of infected necrosis in severe acute pancreatitis.

BACKGROUND: Infected pancreatic necrosis (IPN) is the main cause of death in patients with severe acute pancreatitis. Therefore an early prediction of IPN is of utmost importance. AIM: Analysis of new blood variables as potential early predictors to differentiate between IPN and sterile pancreatic necrosis (SPN). PATIENTS: 64 consecutive patients with acute pancreatitis were enrolled in this prospective study; 29 were suffering from acute oedematous pancreatitis (AIP), and 35 from necrotising disease (NP) as diagnosed by contrast enhanced computed tomography. METHODS: Procalcitonin (PCT) and granulocyte colony stimulating factor (G-CSF) in the serum were examined and compared with C reactive protein (CRP). CRP was measured with a turbidimetric immunoassay (Autokit CRP; Wako, Osaka, Japan), and PCT and G-CSF by ELISA (Lumitest PCT; Brahms Diagnostica, Berlin, Germany; G-CSF-Elisa; R&D Systems, Abingdon, Oxon, UK). Monitoring was performed daily and related to the onset of symptoms. RESULTS: Within the first week, all three variables (CRP, PCT, and G-CSF) were significantly higher in patients with NP than in those with AIP (CRP, p<0.001; G-CSF, p<0. 001; PCT, p<0.001). During the course of the study, 12 of the 35 patients with NP developed late IPN after a median of 20.5 (range 3-49) days. Neither the peak nor the lowest concentrations during the monitoring period were of any value for predicting IPN (median peak values in SPN v IPN: PCT, 0.93 v 1.93 ng/ml; G-CSF, 347 v 421 pg/ml; CRP, 270 v 325 mg/l). CONCLUSIONS: Serum PCT, G-CSF, and CRP concentrations are of similar value for early differentiation between mild and severe acute pancreatitis. However, these variables are not suitable for the early prediction of IPN.

Acute Disease↗
PubMed1999

Susceptibility to local infection in biological internal fixation. Experimental study of open vs minimally invasive plate osteosynthesis in rabbits.

Resistance to local infection after fracture fixation with plate osteosynthesis may be influenced by the implantation technique. It is known that the extent of the surgical approach to the bone can compromise the local defence capacity. We have investigated susceptibility to infection after a local bacterial challenge in rabbit tibiae using either the open surgical approach for 'biological' internal fixation of standard 2.0 dynamic compression plates or the method of minimally invasive plate osteosynthesis (MIPO), a percutaneous, tunnelling insertion technique preserving the integrity of the overlying soft tissue. After the wounds had been closed, various concentrations of Staphylococcus aureus were injected in the direct vicinity of the implants. The infection rate for the open surgical technique was 38.5% and that for the MIPO technique, 25%. This difference is not statistically significant (P > 0.05) suggesting that resistance to local infection associated with the MIPO method is at least equivalent to the open approach for plate osteosynthesis.

Animals↗
PubMed1999

Troponin-I for prediction of early postoperative course after pediatric cardiac surgery.

OBJECTIVES: It was the aim of the study to test the prognostic value of cardiac troponin-I (cTnI) concerning the early postoperative course after pediatric cardiac surgery. BACKGROUND: Cardiac troponin-I is a very specific and sensitive marker of myocardial damage in adults and children. As perioperative myocardial damage may be a significant factor of postoperative cardiac performance, serial cTnI values were analyzed in children undergoing open heart surgery. METHODS: Seventy-three children undergoing elective correction of congenital heart disease including atrial and ventricular surgical manipulation were studied. Cardiac troponin-I levels were measured serially and correlated with intra- and postoperative parameters (such as doses and length of inotropic support, renal and hepatic function, duration of intubation). Patients with prolonged postoperative recovery were analyzed with special attention to the cTnI levels. RESULTS: The cutoff point for the definition of a high and a low risk group of cTnI values was set at 25 microg/liter, 4 h after admission to the intensive care unit (ICU) and at 35 microg/liter considering the maximal value of cTnI in the first 24 h in the ICU. The results showed a highly significant correlation between the need for inotropic support, the severity of renal dysfunction and the duration of intubation in relation to the serum levels of cTnI. CONCLUSIONS: Cardiac troponin-I serum levels after open heart surgery in children and infants 4 h after admission to the ICU allowed anticipation of the postoperative course and correlated with the incidence of significant postoperative complications.

Adult↗
PubMed1998

[Experimental reconstruction of the sheep orbit with biodegradable implants].

In a complex animal model in sheep, polydioxanone (PDS) and polylactic membranes were used for the reconstruction of large orbital-wall defects. In a long-term experiment over 1 year, polylactic implants alone showed the best performance as compared with combinations involving autogenous bone grafts and titanium miniplate fixation. As soon as these polylactic implants are approved for human surgery, they will be used to solve the still challenging problem of anatomical reconstruction of large comminuted fractures of more than one orbital wall.

Animals↗
PubMed1998

Assessment of troponin-T for detection of clinical cardiac rejection.

Non-invasive detection of cardiac rejection still remains a challenge after heart transplantation. We assessed troponin-T as a new serum marker to diagnose cardiac rejection. Twenty-five heart transplant patients (Berne) were monitored prospectively for up to 2 years, and compared to 89 retrospectively assessed patients (Stanford). Blood samples (392 Berne and 320 Stanford) were analyzed (creatine kinase, isoenzymes MB activity and MB mass, troponin-T and troponin-I). Regression analysis between the results of these blood samples and cardiac rejection grading from simultaneously performed endomyocardial biopsies was carried out. Troponin-T tests done in two different laboratories showed a good correlation (r = 0.91; P < 0.0001), whereas troponin-T versus troponin-I showed a lower correlation (r = 0.53; P < 0.0001). Troponin-T and -I in contrast to other enzymes were elevated for a longer period (up to 4 weeks before returning to baseline) after transplantation than during conventional cardiac surgery. Beyond 3 months the following correlations were found between troponin-T (new or old test) and the other enzymes (creatine kinase: r = 0.26, MB activity: r = 0.4, and MB mass: r = 0.68). The correlation between the degree of rejection and the enzyme release is poor, however, the best results were obtained for troponin-T (r = 0.22; P < 0.001). We found a low correlation between troponin-T and the degree of rejection beyond 3 months after heart transplantation. Despite a troponin-T elevation in some patients with rejection, the new test is not sensitive enough to be used alone for the non-invasive diagnosis of cardiac rejection.

Biomarkers↗
PubMed1998

Comparison of troponin-I and troponin-T after pediatric cardiovascular operation.

BACKGROUND: Although the diagnostic value of troponin-T in childhood is documented, little is known about the significance of troponin-I. It was the aim of this study to compare the diagnostic value of troponin-I and troponin-T in children and newborns to assess the perioperative potential myocardial damage. METHODS: Forty-eight children, mean, 51+/-54 months (mean value +/-1 standard deviation) (range, 1 day to 204 months) undergoing cardiac operation were prospectively enrolled in the present study. Troponin-I, troponin-T, creatine kinase (CK), and the MB isoenzyme were measured before operation and postoperatively within 2 days. RESULTS: Postoperative values of troponin-I for children undergoing extracardiac operation were in the normal range. In children with interventions through the right atrium (n = 10) the mean value increase to 6.5+/-6.1 microg/L (range, 1.8 to 24.3 microg/L) and even to a mean of 29.9+/-21.1 microg/L (range, 7.5 to 90 microg/L) (p<0.01) in children with atrial and additional ventricular surgical approach (n = 23). Troponin-I was of equal specificity and sensitivity compared to troponin-T, excepted in patients with postoperative renal failure in whom troponin-T raised to false pathological results. CONCLUSIONS: For detection of perioperative myocardial damage troponin-I shows a higher specificity than CK-MB activity and CK-MB mass. The diagnostic value of troponin-I is similar to troponin-T, but compared with troponin-T, it has the advantage of not being influenced by renal failure.

Cardiac Surgical Procedures↗
PubMed1998

[Does surgical approach have an effect on the development of local infection? Animal experiment comparison of conventional open vs. minimally invasive bone plate osteosynthesis (MIPO)].

With a standardised model we investigated the influence of two different surgical approaches to the rabbit tibia for plate osteosynthesis on resistance to local infection after postoperative inoculation of graduated concentrations of staphylococcus aureus at the implant. The infection rate for the minimally invasive plate osteosynthesis with insertion of the implant in closed, soft tissue tunneling technique was 25% (3/12 animals; ID50 = 6.2 x 10(6) CFU) and for the conventional open approach 38% (5/13 animals; ID50 = 2 x 10(6) CFU). This difference is statistically not significant (with P < 0.05).

Animals↗
PubMed1997

Troponin-T: improved diagnostic assessment of myocardial damage in childhood.

Troponin-T (cTnT) as a marker of myocardial damage is well established in adults, but not yet in children. cTnT was measured in 85 children (aged 1 day-204 months, mean 46 months). Twenty-five children were non-surgical patients, with possible myocardial damage suspected on clinical grounds. The other 60 patients had cardiac surgery leading to a defined myocardial damage. In these children, troponin-T (cTnT), creatine kinase activity (CK), creatine kinase-MB activity (CK-MB), and creatine kinase-MB-Mass (CK-MB-Mass) were measured preoperatively and 3-4 times during the first 55 postoperative h. Except in four children with probable preoperative myocardial damage, all troponin-T values were in the normal range (< 0.1 microg/l). All children with intracardiac surgery showed a postoperative increase in troponin-T. Children with extracardiac surgery of the great vessels showed no postoperative increase of troponin-T. For the assessment of myocardial damage, troponin-T was more specific and more sensitive than the other markers tested, troponin-T might significantly improve the diagnostic assessment of myocardial damage in children.

Biomarkers↗
PubMed1996

Relevance, pathogenicity and virulence of microorganisms in implant related infections.

It is impossible to imagine modern medicine today without indwelling devices of various kinds. The time that these implants or prostheses remain in the patient's body can vary from a few hours, e.g. intravenous catheter, to his entire life, e.g. hip prosthesis, heart valve. Besides the indisputable use and advantages of this type of medical intervention for the patient, e.g. saving his life or improving its quality, the associated complications should not be overlooked. One of the most frequent and significant complications of implant surgery is the manifestation of infection in the tissue around the implant. That infection occurs is not surprising since the indwelling devices predispose to bacterial and mycotic infection on the one hand and impede its eradication on the other. The consequences of infection for the patient may mean the loss of regained mobility and independence, hospitalization for sepsis, or even death. Microbes per se are not necessarily pathogenic, however, there are numerous virulence factors which affect the degree of pathogenicity of the microorganisms. These include, for example, various enzymes, (e.g. catalase, hyaluronidase, collagenase and other proteases), and specific surface structures, e.g. the polysaccharide capsules of pneumococci or the lipopolysaccharides of Gram negative bacteria, and the production of bacterial toxins, e.g. leucozidin, streptolysine. The strategies which the pathogenic bacteria employ in their efforts to occupy the host include adherence, penetration and multiplication, antiphagocytosis and serum resistance, the formation of siderophores, antiimmunity, and cell and tissue damage. An attempt will be made here to present an overview of this multifactorial event in which the host obviously plays an important role.

Animals↗
PubMed1996

Infection after intramedullary nailing: an experimental investigation on rabbits.

The purpose of this study was to investigate three relevant aspects of intramedullary nailing in terms of their effect on the occurrence of local infection. In an infection model on the rabbit tibia, the following were compared: a hollow and a solid nail (Experiment I), a reamed with an unreamed technique (Experiment II), and a steel with a titanium nail (Experiment III). In order to minimize the number of animals required, a grouped sequential procedure combined with an "up and down" dosage technique was applied. Microbiological evaluation was both qualitative and quantitative. The results in Experiment 1 (n = 44) indicated an infection rate for the hollow nail (59%) almost double that of the solid nail (27%) (P < or = 0.05). Experiment II (n = 44) produced an infection rate of 50% for the unreamed technique compared to 64% for the reamed technique, a difference which, on the basis of the number of bacteria present, was also statistically significant (P < or = 0.05). In Experiment III (n = 44) an infection rate of 82% was recorded for the steel nail compared to 59% for the titanium nail (P < or = 0.05). The results of the three experiments are only partially comparable with each other because of the grouped sequential procedure and the different inocula used. Nonetheless it would seem that the dead space inherent in the design of the hollow nail represents a considerable risk with regard to the occurrence of local infection. Reaming the medullary cavity with the attendant reduction in local vascularity and necrosis and the lesser biocompatibility of steel compared to titanium may be additional risk factors which should not be overlooked.

Animals↗
PubMed1996

Infection after open reduction and internal fixation with dynamic compression plates--clinical and experimental data.

Infection rates for open reduction and internal fixation (ORIF) with the DCP in clinical studies are based on heterogeneous data on general risk factors and do not take into account the direct effect of the implant (material, design, surface, technique). The initial degree of bacterial contamination is generally unknown and the applied definition of the term infection is not mentioned. In our own prospective randomized clinical study including 281 cases of ORIF with the DCP (154 steel vs 127 titanium), the influence of the implant material on susceptibility to local infection was examined in relation to initial bacteria contamination (109 non-contaminated / 172 contaminated). Although in the group of contaminated DCPs the difference in the infection rates for stainless steel (sSt) and commercially pure titanium (cpTi) showed no statistical significance, a tendency was apparent. In an animal experiment, the lower rates of infection for c.p.Ti-DCP compared to sSt-DCP in the presence of a local bacterial challenge could be demonstrated with statistical significance. The need for further experimental research in the field of implant related local infection after ORIF will be discussed and strategies for further investigations proposed.

Animals↗
PubMed1996

Influence of materials for fixation implants on local infection. An experimental study of steel versus titanium DCP in rabbits.

Resistance to infection may be influenced by foreign bodies such as devices for fracture fixation. It is known that stainless steel and commercially-pure titanium have different biocompatibilities. We have investigated susceptibility to infection after a local bacterial challenge using standard 2.0 dynamic compression plates of either stainless steel or titanium in rabbit tibiae. After the wounds had been closed, various concentrations of a strain of Staphylococcus aureus were inoculated percutaneously. Under otherwise identical experimental conditions the rate of infection for steel plates (75%) was significantly higher than that for titanium plates (35%) (p < 0.05).

Animals↗