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S Arens

Publications and source records attributed to S Arens.

29 records · Page 2Linked to original sources

Evaluation of Glucocard Memory 2 and Accutrend sensor blood glucose meters.

The performance and practicability of 2 blood glucose meters (Glucocard Memory 2 and Accutrend sensor) were evaluated. Both glucose meters produced acceptably precise results in the hyper- and normoglycaemic concentration ranges. In the hypoglycaemic concentration range, the imprecision of Accutrend sensor was much higher than recommended by the American Diabetes Association. Within-run coefficients of variation for Glucocard Memory 2 were 6.3%, 3.9% and 2.4% at glucose concentrations of 1.7 mmol/l, 5.8 mmol/l and 11.7 mmol/l, respectively: for Accutrend sensor these were 15.2%, 5.0% and 1.2% at respective concentrations of 0.9 mmol/l, 4.2 mmol/l and 19.6 mmol/l. Between-day coefficients of variation for Glucocard Memory 2 were 4.8% and 3.5% at glucose concentrations of 3.9 mmol/l and 17.2 mmol/l, respectively and for Accutrend sensor they were 3.8% and 2.9% at glucose concentrations of 3.8 mmol/l and 18.7 mmol/l, respectively. Results were linear over a range of 1.6 mmol/l -29.7 mmol/l for Glucocard Memory 2 and 1.6 mmol/l -33.3 mmol/l for Accutrend sensor. Results of both blood glucose meters correlated closely with the hexokinase/glucose-6-phosphate dehydrogenase laboratory method. Ninety-eight percent of both Glucocard Memory 2 and Accutrend sensor results were within 20% of the comparison method values. Ninety-three percent of the Glucocard Memory 2 and 96% of the Accutrend sensor results were within 15% of the comparison method results. An inverse relation between the glucose readings and haematocrit values was observed for both blood glucose meters in the hyperglycaemic range and this effect was more pronounced for Accutrend sensor. In the normo- and hypoglycaemic ranges the effect was insignificant and absent, respectively. Minimum sample volume for Glucocard Memory 2 was 3 microliters and for Accutrend sensor it was 9 microliters. Lower sample volumes gave erroneous results. Presenting more than the required volume had no effect on results.

Analysis of Variance↗

[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↗

[Rate of infection in trauma surgery. An overview based on recent German language literature].

Infection rates are important markers for clinical quality assurance. For internal control, they may only be used under the condition of homogeneous data collection and evaluation according to identical standard operating procedures during the entire investigation period. For inter-hospital comparison, they may only be used if additionally the observed patient groups are well defined and comparable. A survey of the infection rates published during the last 6 years in the German traumatological literature (n = 71) indeed shows (concerning series later than 1985) similar infection rates for procedures in less and in more problematic anatomical regions and in clean and contaminated situations of about 2-3%, after open injuries sporadically max. 10%. Finally, it is demonstrated that conclusions concerning a general "risk of infection" based on infection rates for specific surgical procedures are not possible and vice versa. We strongly recommend the future application of a standardized definition of wound infection. The differentiation between deep and superficial infection should be abandoned. For all mentioned "infection rates" it should be indicated whether it is with reference to the risk of infection of a specific procedure or only a general statement.

Cross-Sectional Studies↗

Dissociation between adenosine release, MVO2, and energy status in working guinea pig hearts.

Rapid adaptation of ATP formation and coronary flow is required when cardiac work is altered. Cardiac energy status was proposed to control both oxygen consumption (MVO2) and release of vasoactive adenosine (AR). To investigate the hypothesis of a linear relation between free AMP and AR, we employed 31P nuclear magnetic resonance (NMR) in a newly elaborated guinea pig heart performing pressure-volume work. Under basal conditions, MVO2 was 7.8 +/- 1.0 mumol.min-1.g-1, free AMP 297 +/- 189 nM and AR 226 +/- 179 pmol.min-1.g-1 (n = 29). Decreasing arterial PO2 by 50% reduced MVO2 and increased free AMP by 29%; however, AR rose threefold (n = 5). Doubling oxygen content of the perfusion medium (fluorocarbon emulsion) did not alter MVO2, free AMP, or AR (n = 6). When afterload was doubled, MVO2 increased (+45%) and AR decreased (-60%) despite no change in ADP or AMP (n = 6). Dobutamine increased MVO2 (+50%) and AMP (-98%); however, AR rose more than five times (n = 8). Switching substrates from glucose + pyruvate to glucose diminished MVO2 and increased ADP twofold and AMP fourfold, whereas AR remained constant (n = 6). Our findings demonstrate that cardiac energy status is also not the prime regulator of oxidative phosphorylation in the isolated heart. Changes in the oxygen supply-to-demand ratio induced a rise in AR that exceeded by far the increase in free AMP. Thus, additional factors, possibly inhibition of adenosine kinase, influence the release of vasoactive adenosine.

Adenosine↗

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↗

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↗

[Prophylactic and therapeutic use of antibiotics in trauma surgery].

Antibiotic treatment in traumatology (either for prophylactic or therapeutic purposes) can reduce the local bacterial contamination and can therefore improve the balance in favor of the host defence capacity. Above all, its value has to be measured depending on the local bacterial colonization in the individual case and to what extent this is the essential pathogenetic factor for development of the infection or for resistance to infection. In situations where local host damage (either traumatic or iatrogenically/surgically induced) is the predominant cofactor for the development or persistence of infection, the antibiotic or other pharmacological reduction of the bacterial colonization is of secondary or no importance at all. In view of this, the indications for routine antibiotic prophylaxis or therapy, which so far have been accepted as valid, should be reconsidered. On the one hand, excellent hygienic conditions have increasingly reduced the relative importance of bacterial contamination in aseptic procedures. On the other hand, the surgical-technical evolution in the last 5 years (such as biological osteosynthesis, unreamed intramedullary nailing, stepwise definite stabilization in complex fractures, initial open wound treatment and very early plastic reconstruction in open fractures, as well as radical necrectomy in chronic infection of bones and soft tissues) could create a significant improvement in the conditions concerning prevention and treatment of infection. Therefore, the relative importance of adjuvant antibiotic treatment is considerably less. Based on previous studies, the publications of the past 3 years focusing on this aspect are examined critically. Finally, detailed recommendations are defined and advice given for well-aimed, controlled continuation studies.

Antibiotic Prophylaxis↗

[Titanium implants in accident surgery--when are they necessary?].

The decision on whether to use stainless steel or commercial pure titanium as an implant material in open reduction and internal fixation (ORIF) should depend on biomechanical behavior, biocompatibility, resistance to infection, handling characteristics and costs. Based on the results of a prospective randomized clinical study including 281 DC-plates and data available in the literature we will present recommendable guidelines for the choice of the appropriate implant material for individual cases of bone surgery.

Bone Plates↗

Induction of monocyte chemotactic proteins MCP-1 and MCP-2 in human fibroblasts and leukocytes by cytokines and cytokine inducers. Chemical synthesis of MCP-2 and development of a specific RIA.

Monocyte chemotactic proteins (MCP) belong to a group of structurally and functionally related factors, called chemokines. To facilitate additional characterization of the recently identified MCP-2, the 76-residue protein was chemically synthesized. The synthetic 7-kDa monomeric protein was chemotactic for monocytes at 1 nM and was biochemically similar to natural MCP-2. Sensitive radioimmunoassays for both MCP-1 and MCP-2 were developed. These RIAs were specific in that no cross-reactivity could be observed, and other chemokines or cytokines were not detected. Induction of MCP-1 and MCP-2 in human diploid fibroblasts and peripheral blood leukocytes as well as osteosarcoma, epidermal carcinoma, and melanoma cells by the cytokines IL-1 beta, IFN-beta, and IFN-gamma and cytokine inducers such as dsRNA, virus, endotoxin, mitogen, and phorbol ester was studied. In connective tissue cells, IL-1 beta was the best inducer of MCP-1, but IFN-gamma was a superior inducer of MCP-2. Mononuclear cells also proved to be a source of MCP-1 and MCP-2 when stimulated by most of the inducers tested. Granulocytes, however, were inefficient producers. Measles virus induced MCP-1 and MCP-2 in most cell types. In general, the yields of MCP-2 were at least 10-fold lower than those of MCP-1. It is concluded that, although MCP-2 is often coproduced with MCP-1, regulation of expression of the two chemokines is not identical. It remains to be studied under which pathological conditions MCP-2 is released in vivo and whether MCP-1 and MCP-2 can activate different target cells.

Cells, Cultured↗

[Local and systemic trauma in plate osteosynthesis of femur shaft fracture].

Compression plating of fractures of the femur has a number of logistic advantages over intramedullary stabilization techniques though it is equally demanding for the surgeon. In this retrospective study of 77 cases, we try to show that compression plating of fractures of the femoral shaft is still a viable alternative to intramedullary fixation, especially in the light of local complications, postoperative systemic implications for the patient with multiple injuries, and the time required to achieve bone union. The data relating to all three of these aspects permit the conclusion that the results reached with compression plating of both simple and comminuted femoral shaft fractures are comparable to those reported following intramedullary nailing. Our treatment regimen does not involve a higher risk to the patient.

Adult↗

Influence of the design for fixation implants on local infection: experimental study of dynamic compression plates versus point contact fixators in rabbits.

OBJECTIVES: Comparison of infection resistance after local bacterial challenge associated with two different designs for fixation implants: the conventional dynamic compression plate (DCP) and the point contact fixator (PC-Fix). DESIGN: Randomized, prospective study in experimental animals. Grouped sequential experimental procedure. Observation time was twenty-eight days, with twenty animals per group. SETTING: Following surgery, animals were kept without restrictions in individual hutches. ANIMALS: Forty White New Zealand rabbits. Thirty-eight animals, nineteen per group, were included in the final evaluation. INTERVENTION: Under sterile conditions, specially manufactured titanium DCP or PC-Fix of identical dimensions were fixed to rabbit tibiae. After wound closure, different concentrations of Staphylococcus aureus, between 2 x 10(4) and 2 x 10(8) colony-forming units (CFU), were inoculated percutaneously at the implant site. MAIN OUTCOME MEASUREMENTS: Implants, underlying bone, and surrounding soft tissues were removed under sterile conditions and quantitatively evaluated for bacterial growth. Infection was defined as positive bacterial growth at the bone-implant interface. RESULTS: The overall infection rate was 45 percent. The infection dose of 50 percent (ID50) was 7.08 x 10(5) CFU for the DCP group and 8.51 x 10(6) CFU for the PC-Fix group. The infection rate was 63 percent (twelve of nineteen animals) for the DCP group and 26 percent (five of nineteen animals) for the PC-Fix group. This difference was statistically significant (p = 0.022). CONCLUSIONS: After local bacterial challenge, we found a statistically significant difference in the infection rates depending on the implant design. The higher infection resistance associated with the PC-Fix design seems to be related to the reduced contact area at the bone-implant interface.

Animals↗