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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    The chemical educator 3 (1998), S. 1-11 
    ISSN: 1430-4171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An undergraduate instrumental analysis laboratory exercise is presented for the characterization of light emission generated using electrochemiluminescence (ECL). ECL involves the electrochemical generation of excited states and as such is a sensitive probe of electrochemical, electron-transfer and energy-transfer processes at electrified interfaces. An objective of this experiment is to have students develop an understanding of the mechanisms and factors affecting ECL. Also, this exercise gives students experience in coupling two powerful analytical techniques: electrochemistry and spectroscopy. With the recent development of ECL technology for use in clinical diagnostics applications, this exercise also facilitates discussions on the importance of basic research and the practical aspects of taking a technology from the bench top to commercial reality.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Insectes sociaux 46 (1999), S. 131-136 
    ISSN: 1420-9098
    Keywords: Key words:Vespula, Polistes, Vespidae, foraging, resource choice.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary: The role of visual cues provided by resident wasps on resource choice by yellowjacket and paper wasp foragers was investigated. Large spring queen yellowjackets and small early season yellowjacket foragers (Vespula germanica, Vespula maculifrons, and Vespula vidua) were extracted in hexane to remove odors and posed as though feeding at petri dish feeders bearing daisy-like flower models, equipped with microcapillary feeding tubes, and containing 1:3 honey:water solution. An array of five feeders was presented to foragers at a suburban and a woodland site in Saratoga Springs, New York. The visual cues provided by resident wasps influenced resource choice by approaching social wasp foragers. Vespula germanica, an introduced yellowjacket species that tends to dominate at rich resources, was the only wasp visiting the suburban feeders. Foragers of this species preferentially fed on feeders and flowers with posed wasps and fed most often next to large wasps. Polistes fuscatus foragers at the woodland site similarly preferred to feed on occupied feeders and flowers. Vespula maculifrons and V. consobrina preferentially visited unoccupied feeders. Individual V. maculifrons, V. consobrina and V. vidua foragers that landed on occupied feeders all preferentially visited unoccupied flowers on those feeders. Vespula vidua and V. flavopilosa foragers did not demonstrate a feeder preference based on the presence/absence of posed wasps. Vespula consobrina foragers that visited occupied feeders preferred those occupied by extracted V. maculifrons queens and workers; no other wasps showed species based landing preferences.
    Type of Medium: Electronic Resource
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  • 13
    ISSN: 0949-2925
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Type of Medium: Electronic Resource
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  • 14
    ISSN: 1432-1238
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 15
    ISSN: 1438-2199
    Keywords: Rat striatum ; Medium spiny neuron ; Adenosine AZA receptor ; NMDA receptor channel ; Whole-cell patch clamp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Whole-cell patch clamp experiments were carried out in rat striatal brain slices. In a subset of striatal neurons (70–80%), NMDA-induced inward currents were inhibited by the adenosine AZA receptor selective agonist CGS 21680. The non-selective adenosine receptor antagonist 8-(p-sulphophenyl)-theophylline and the AZA receptor selective antagonist 8-(3chlorostyryl) caffeine abolished the inhibitory action of CGS 21680. Intracellular GDP-β-S, which is known to prevent G protein-mediated reactions, also eliminated the effect of CGS 21680. Extracellular dibutyryl cAMP, a membrane permeable analogue of cAMP, and intracellular Sp-cAMPS, an activator of cAMP-dependent protein kinases (PKA), both abolished the CGS 21680-induced inhibition. By contrast, Rp-cAMPS and PKI 14–24 amide, two inhibitors of PKA had no effect. Intracellular U-73122 (a phospholipase C inhibitor) and heparin (an inositoltriphosphate antagonist) prevented the effect of CGS 21680. Finally, a more efficient buffering of intracellular Ca2+ by a substitution of EGTA (11 mM) by BAPTA (5.5 mM) acted like U-73122 or heparin. Hence, AZA receptors appear to negatively modulate NMDA receptor channel conductance via the phospholipase C/inositoltriphosphate/Ca2+ pathway rather than the adenylate cyclase/PKA pathway.
    Type of Medium: Electronic Resource
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  • 16
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The biocompatibility and osseous integration of a new composite material made of polyurethane and a calcium silicophosphate ceramic was investigated in a loaded implant model in sheep and compared to that of commercially pure titanium. Six months after implantation, interfacial shear strength was higher between the titanium and bone than between the composite and bone. After 2 years, however, the shear strength was significantly higher in the composite group. Histologically, both implants were surrounded by bone and fibrous tissue and there were no signs of inflammation. Direct contact of bone on the composite surface increased significantly with time, whereas there was no time-dependent increase of bone contact on titanium. It can be concluded that the biocompatibility and osseous integration of the composite was very good in the loaded implant model used. It is therefore suggested that the new composite is a promising biomaterial for orthopaedic implants.
    Type of Medium: Electronic Resource
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  • 17
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The aim of this study was to evaluate the healing capacity of proximal anterior cruciate ligament (ACL) ruptures following primary repair with and without a bioresorbable augmentation. The ACL was transected at the femoral origin in the right knee joint of 24 sheep. The ACL was repaired in eight sheep (group B) without, and in eight sheep (group C) with a bioresorbable augmentation. Eight sheep without repair served as a control (group A). No immobilization was performed in any group. The sheep were sacrificed 13 weeks post-operatively. Macroscopically, all repaired ACLs were healed. The augmentation device was broken in all cases, but not completely degraded. In group A, none of the transected ACLs had healed. The anterior drawer under a load of 50 N was significantly lower in group C than in group A (p〈0.01). No significant difference was seen between groups B and A. The distribution and extent of chondromalacia (CM) in the operated knees depended on the type of operative treatment (p〈0.01). Groups A and B showed significantly more CM in the operated knee than in the non-operated knee (each p〈0.05). Proximal ACL ruptures can heal in sheep after both non-augmented and augmented ACL repair with free-functional rehabilitation. However, augmented repair leads to significantly better stability of the knee joint compared to transected controls and better limits the development of degenerative changes.
    Type of Medium: Electronic Resource
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  • 18
    ISSN: 1433-0385
    Keywords: Key words: Odontoid fracture ; Non union ; Pseudarthrosis ; Transarticular screw fixation ; Os odontoideum. ; Schlüsselwörter: Densfraktur ; Pseudarthrose ; operative Behandlung ; konservative Behandlung ; transartikuläre Verschraubung C1/C2 ; Os odontoideum.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung. Einleitung: Die überwiegende Mehrzahl aller Denspseudarthrosen liegt eine vorausgegangene Verletzung zugrunde. Bei dem am häufigsten vorkommende Frakturtyp II mit einem Bruchverlauf im Bereich der Densbasis entsteht auf Grund besonderer anatomischer Bedingungen auch besonders oft ein Falschgelenk. Entscheidende Mechanismen bei seiner Entstehung sind eine ungenügende innere oder äußere Ruhigstellung des Bruchs sowie ein persistierender Frakturspalt. Methoden und Ergebnisse: Bei einer eigenen Nachuntersuchung von 71 Patienten nach operativer Stabilisierung einer Densfraktur mit 2 Schrauben fanden wir 8mal eine Pseudarthrose. Bei 3 Patienten hatte der Abstand zwischen Unfall und Operation mehr als 5 Wochen betragen, 7mal war es nicht gelungen, den Frakturspalt ausreichend anzunähern. Technische Fehler wie eine ungenügende Reposition (n = 1) sowie Schraubenfehllagen (n = 3) waren weitere Ursachen. Ein Os odontoideum muß nach entsprechenden Berichten im Schrifttum und eigenen Erfahrungen bei einem großen Teil der Patienten als Pseudarthrose nach einer Verletzungen der Synchondrose im Kindesalter angesehen werden. Die wichtigste diagnostische Maßnahme bei Denspseudarthrosen stellt eine Funktionsuntersuchung der oberen HWS in maximaler Flexion und Extension dar. Wir schlagen eine Einteilung posttraumatischer Denspseudarthrosen in 4 Typen vor: Typ I entspricht einer straffen „Pseudarthrose“ in weitgehend anatomischer Stellung des Dens axis und ohne Zeichen der Instabilität im ehemaligen Frakturbereich. Typ II beschreibt eine stark verschobene Pseudarthrose, die sich nicht ohne weiteres reponieren läßt, Typ III eine instabile Pseudarthrose und Typ IV ein posttraumatisches Os odontoideum. Schlußfolgerungen: Therapieempfehlungen müssen bei Denspseudarthrosen entsprechend differenziert gegeben werden. Instabile Denspseudarthrosen (Funktionsaufnahmen) verursachen fast immer deutliche Beschwerden und bedürfen wegen der immer wieder beschriebenen Gefahr einer akuten oder chronischen Myelopathie – ebenso wie Ossa odontoidea – der operativen Stabilisierung. Bei erheblich dislozierten Pseudarthrosen sollte zunächst ein geschlossener Repositionsversuch unternommen werden. Operationsmethode der Wahl ist die dorsale transarticuläre Verschraubung und Fusion C1/C2, möglichst in percutaner Technik. Straffe, „stabile“ Denspseudarthrosen im Sinne eines persistierenden Frakturspalts bei beschwerdefreien Patienten sollten anfangs röntgenologisch kontrolliert; bleibt die Stellung des Dens unverändert, kann weiter konservativ behandelt werden.
    Notes: Summary. Introduction: Injuries precede the vast majority of all odontoid pseudarthroses. Because of specific anatomic conditions type II injuries lead more often than other types to non unions. For its development insufficient internal or external fixation and a persisting fracture gap are crucial. Methods and results: In 71 patients after operative stabilization of odontoid fractures with two anterior lag-screws we detected 8 non unions. In 3 patients the interval between accident and operation amounted to more than 5 weeks, seven times we did not succeed in closing the fracture gap. Technical mistakes like insufficient reduction (n = 1) or screw misplacement (n = 3) were additional reasons. According to the literature and own observations an os odontoideum must be considered in most instances as a pseudarthrosis after a lesion of the subdental synchondrosis in childhood. The most important diagnostic tool in odontoid non unions is a dynamic examination of the upper cervical spine under fluoroscopic control in maximum flexion and extension. We propose a classification of posttraumatic dens non unions into 4 types. Type I corresponds to a stable „non union“ in approximate anatomical position of the dens and without signs of instability in the former fracture zone. Typ II describes a relatively stable grossly displaced non union that is not to be reduced by simple, closed means. Typ III means an unstable non union and Typ IV a posttraumatic os odontoideum. Conclusions: Therapeutical recommendations need to be differentiated. Unstable non unions are most often responsible for persistent pain, may result in acute or chronic myelopathie and therefore – as well as ossa odontoidea – need operative fixation. In considerably displaced non unions a closed reduction manoeuver with long term traction should be tried. The operative treatment of choice is the posterior transarticular screw fixation C1/C2 desirably in a percutaneous technique. Tight, “stable” pseudarthroses in the sense of a persisting fracture gap in painfree patients should first be controlled radiologically. If the odontoid position remains unchanged, non operative treatment may be continued.
    Type of Medium: Electronic Resource
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  • 19
    Electronic Resource
    Electronic Resource
    Springer
    Der Chirurg 70 (1999), S. 1294-1301 
    ISSN: 1433-0385
    Keywords: Key words: Traumatic knee dislocation ; Knee ligament rupture ; Cruciate ligament reconstruction ; Long-term results ; Prognostic factors. ; Schlüsselwörter: Traumatische Knieluxation ; Kniebandruptur ; Kreuzbandrekonstruktion ; Langzeitergebnisse ; prognostische Faktoren.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung. Einleitung: Die traumatische Luxation ist die schwerste ligamentäre Verletzung des Kniegelenks und tritt mit 0,2–0,3 % aller Gelenkluxationen selten auf. Zur konservativen und operativen Behandlung liegen einige abgeschlossene Langzeitstudien vor. Vor allem aufgrund der meist geringen Fallzahlen sind die Behandlungsempfehlungen und Therapieschemata aber noch immer uneinheitlich. Methoden und Ergebnisse: Zwischen 1974 und 1994 wurden in unserer Klinik 38 Patienten mit dokumentierter Knieluxation operativ behandelt. 34 Patienten konnten nach 3–16 Jahren (Mittelwert: 8,6 Jahre) nachuntersucht werden. Bei 29 der nachuntersuchten Patienten war die Rekonstruktion beider Kreuzbänder erfolgt. Bei den restlichen Fällen erfolgte keine Versorgung der Kreuzbandläsionen. Bei 90 % der nachuntersuchten Patienten wurde eine gute Kniestabilität ermittelt, allerdings bestand auch in 90 % eine Bewegungseinschränkung. Die posttraumatische Arthrose war meist leicht bis mittelschwer; 35 % der Patienten erreichten gute bis sehr gute Ergebnisse im Lysholm-Score. Schlußfolgerungen: Als prognostisch günstige Faktoren erwiesen sich bei dieser Untersuchung ein Alter zum Unfallzeitpunkt von weniger als 40 Jahren, Traumen mit geringer Rasanz, wie z. B. Sportunfälle, eine frühe Rekonstruktion beider Kreuzbänder und eine frühfunktionelle Nachbehandlung.
    Notes: Summary. Introduction: Traumatic dislocation is the most severe ligamentous injury of the knee. The indications for operative and conservative treatment are still controversial. Methods and results: From 1974 to 1994, 38 patients with documented knee dislocation were treated operatively in our department. Thirty-four of these patients were followed up for 3–16 years (mean: 8.6 years). In 29 cases of the follow-up group, reconstruction of both cruciate ligaments was performed. In the remaining cases the cruciate ligaments were left alone. At the time of follow-up, 90 % of the patients showed good knee stability, but 90 % had lack of motion as well. Post-traumatic osteoarthritis was mostly mild to moderate. Thirty-five percents of the patients achieved excellent to good results in the Lysholm Score. Conclusions: Positive prognostic factors were an age less than 40 years at the time of the accident, a low-energy trauma, e. g., a sports-related injury, early reconstruction of both cruciate ligaments, and initial postoperative functional treatment.
    Type of Medium: Electronic Resource
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  • 20
    Electronic Resource
    Electronic Resource
    Springer
    European journal of plastic surgery 22 (1999), S. 80-84 
    ISSN: 1435-0130
    Keywords: Key words Carpal tunnel syndrome ; Long incision ; Short incision ; Endoscopic release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The results of open carpal tunnel release using a short incision (2.5 cm) have been compared with those following a long incision (4.5 cm) in a prospective randomized study. Eighty patients were operated upon with a follow-up rate of 100%. The variables examined included grip strength, key and pulp pinch strength, sensory function and scar tenderness. Subjective variables such as tingling, numbness and night symptoms were specifically enquired into, and time for return to work was noted. The examinations took place pre-operatively, as well as one, two, three and six weeks post-operatively. Median time for return to work was 21 days for the short incision group and 18 days for the long incision group. The long incision resulted in a significant 10% loss of strength only at week three, otherwise no significant difference was found between the results of the two groups.
    Type of Medium: Electronic Resource
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