Ternary transition-metal fluoride precursors for the fluorolytic sol-gel route: new insights into speciation and decomposition.

The nanoscaled ternary transition-metal fluorides Li3MF6 (M = V, Fe, Mn) and Li2NiF4 are promising candidates for cathode materials in high-voltage lithium-ion batteries. The fluorolytic route to these compounds relies on thermal decomposition of a hitherto uncharacterised precursor mixture produced from acetylacetonates and hydrofluoric acid. By addition of pyridine, different cationic, electroneutral and anionic complexes containing the motifs [MFn]((3-n)+) (n = 0-4) have been trapped and characterised by single-crystal X-ray diffraction and IR spectroscopy. Based on the results, a model of successive and incomplete fluorination is proposed for the speciation and formation of the precursor. The decomposition of the latter has been monitored via thermogravimetry (TG) and differential scanning calorimetry (DSC).

A rare case of obstructive right atrial lipoma.

Benign cardiac tumours are rare and cardiac lipomas account only for a small fraction among those. Most of these tumours differ in terms of clinical manifestation, diagnosis, morphology and size, and are therefore not diagnosed easily unless they become symptomatic. We report the case of a 71-year-old Caucasian woman with recurrent episodes of shortness of breath presenting with an acute exacerbation of dyspnoea and hypertensive crisis. Diagnosis of a right atrial lipoma with a coexisting patent foramen ovale was established on echocardiography and computed tomography, and the patient was evaluated for elective surgery. Comprising the entire free wall of the right atrium, the tumour was removed during open heart surgery on cardiopulmonary bypass. The right atrium and the orifices of both the superior and inferior vena cava were reconstructed with bovine pericardium. No evidence of tumour relapse was observed during successive follow-up visits.

[Quality of anesthesiological expert opinion in medical claims cases]. / Qualität anästhesiologischer Gutachten bei medizinischen Schadensfällen.

Expert opinions have an important place for expert testimony in medical disputes. The report should contain a summary about facts and causality between the damage and the medical treatment in question as well as describe the current medical standard. The fulfillment of scientific criteria was investigated in 179 anesthesiological expert opinions from 150 arbitration cases. Anesthesiological expert reports (2005-2007) of the Arbitration Board of the North German Medical Associations were analyzed in terms of structure, general form of assessment and scientific substantiation of statements. Patient damage was confirmed in 76%, treatment failure in 29% and negligent malpractice in 17% of the reports. In 78% of the reports the facts were presented correctly and in 64% the question was answered whether the incident would have occurred even during adequate and professional action. Conclusive statements about the causality between the damage and the medical treatment in question were available only in 60% of the reports. The study findings suggest that anesthesia expert reports present a high incidence of non-scientific claims. The development of guidelines for expert witnesses by the medical societies is urgently recommended.

Immediate, single stage, truly anatomic zirconia implant in lower molar replacement: a case report with 2.5 years follow-up.

This report demonstrates the clinical use of a modified, truly anatomic, root-analogue zirconia implant for immediate replacement of a two-rooted, left first mandibular molar. A 50-year-old female patient with chronic apical periodontitis of the left mandibulary first molar was referred and the tooth was extracted. The mesial root had to be removed surgically due to a root fracture. A truly anatomical, root identical, roughened zirconia implant modified by macro-retentions was manufactured and placed into the extraction socket by tapping 7 days later. After 4 months a composite crown was cemented in place. No complications occurred during the healing period. A good functional and aesthetic result was achieved with minimal bone resorption and soft tissue recession at 30 months follow-up. This report describes the successful clinical use of an immediate, single stage, truly anatomical root-analogue zirconia implant for replacement of a two-rooted tooth. Significant modifications such as macro-retentions yielded primary stability and excellent osseointegration. This novel approach is minimally invasive, respects the underlying anatomy, aids socket prevention, is time- and cost-saving with good patient acceptance as there is no need for bone drilling, sinus lift, bone augmentation or other traumatic procedures.

Pancreatic graft survival despite partial vascular graft thrombosis due to splenocephalic anastomoses.

Thrombotic complications following pancreas transplantation are still the most common cause of nonimmunologic graft loss. The aim of this study was to analyze pancreatic graft function after partial arterial graft thrombosis and the investigation of the pancreatic arterial anatomy with regard to intraparenchymal anastomoses. We retrospectively analyzed the data for 175 consecutive pancreas transplants performed between January 2002 and October 2007. Selective Y-graft angiography was performed in 10 and rubber-milk injection in 5 fresh pancreas specimens. Thrombosis of one leg of the Y-graft was diagnosed in 18 (10.3%) patients. Only one of these patients with thrombosis of the splenic artery required exogenous insulin. Sufficient graft perfusion was demonstrated in all of the remaining grafts. One graft was lost due to acute rejection. In all specimens angiography showed an excellent perfusion of the pancreaticoduodenal arcade, even after selective cannulation of the splenic artery. Arterial collaterals between the gastroduodenal, splenic artery and the superior mesenteric artery were demonstrated. Our results demonstrate that global perfusion of the pancreatic graft and sufficient graft function is sustained after the thrombotic occlusion of one branch of the Y-graft by a complex system of intraparenchymal anastomoses. These anatomical findings may have consequences for resection strategies in pancreas surgery.

[Anatomical considerations on treatment strategies for compression syndromes of the fibular nerve in the proximal leg]. / Anatomische Grundlage zur Spaltung des Septum Intermusculare Anterius bei der Behandlung des N. peronaeus-Kompressionssyndroms.

BACKGROUND: Posttraumatic or iatrogen compression syndromes of the common fibular nerve (CFN) are frequent. Based on previous anatomical investigations the aim of this study was to analyse the course of the CFN along the proximal portion of the leg with respect to its relationship to the anterior intermuscular septum (AIS). Further sites of constriction or fibrous fixation should be defined. MATERIAL AND METHODS: Anatomical dissection of 111 cadaveric leg specimens was performed. Twenty additional legs were used for histological examination of the respective region within the AIS of the leg. By means of medical records of three patients our current treatment strategy is demonstrated. RESULTS: A tight fixation of the most proximal motor branch of the deep fibular nerve (DFN) within the AIS at its entering point to the anterior compartment could be demonstrated. CONCLUSION: We conclude, that selective decompression not only of the CFN, but of the DFN branches which are fixed in the AIS along their course through the proximal portion of the leg, is mandatory during compression syndromes of the CFN.

Ropivacaine plasma concentrations during 120-hour epidural infusion.

The pharmacokinetics of ropivacaine were evaluated during long-term continuous epidural analgesia (CEDA) for about 120 h. The total and free plasma concentrations of ropivacaine and the alpha1-acid glycoprotein (AAG) concentration were measured in 12 patients after total knee arthroplasty. The infusion rate was adjusted according to patients' analgesic needs or side effects. The mean (SD) rate of infusion of ropivacaine (Naropin 2 mg ml(-1)) was 14.6 (3.2) mg h(-1) on the day of surgery and was increased after surgery to 15.4 (4.4) mg h(-1) on days 1-5. This was equivalent to an absolute dose of 1786 (553) mg of ropivacaine over the entire infusion period. After an initial increase, the mean free ropivacaine plasma concentration nearly plateaued and than decreased slightly after approximately 70 h. The individual peak free plasma concentration was 0.096 (0.034) microg ml(-1). The highest individual free plasma concentration was 0.16 microg ml(-1). The individual peak total plasma concentration, 4.1 (1.2) microg ml(-1), was achieved after 67.7 (16.5) h, although the AAG concentration increased throughout the observation period. Our data support the safety and efficacy of long-term ropivacaine CEDA.

Real-time monitoring of electrically stimulated norepinephrine release in rat thalamus: II. Modeling of release and reuptake characteristics of stimulated norepinephrine overflow.

As in the preceding study, electrical stimulation was used to effect release overflow of norepinephrine in the rat thalamus. Using a weak electrochemical pretreatment of a carbon fiber electrode, it was possible to "tune in" the electrochemical response signal for norepinephrine without metabolite interference. This reasonably selective signal was then used to study the degradation of norepinephrine release ability caused by prolonged stimulation. Further, the signals were modeled by the method used successfully for stimulated dopamine overflow, providing hitherto unavailable information on the temporal and spatial characteristics of norepinephrine release overflow. Pertinent comparisons between the release characteristics of the dopamine and norepinephrine systems show that the half-life for norepinephrine in the extracellular fluid space is approximately 1 s in thalamus compared with 33 ms for dopamine in caudate.

Regulation of transient dopamine concentration gradients in the microenvironment surrounding nerve terminals in the rat striatum.

Synaptic overflow of dopamine in the striatum has been investigated during electrical stimulation of the medial forebrain bundle in anesthetized rats. Dopamine has been detected with Nafion-coated, carbon-fiber electrodes used with fast-scan voltammetry. In accordance with previous results, dopamine synaptic overflow is a function of the stimulation frequency and the anatomical position of the carbon-fiber electrode. In some positions the concentration of dopamine is found to respond instantaneously to the stimulus when the time-delay for diffusion through the Nafion film is accounted for. In these locations the measured rates of change of dopamine are sufficiently rapid such that extracellular diffusion is not apparent. The rate of dopamine overflow can be described by a model in which each stimulus pulse causes instantaneous release, and cellular uptake decreases the concentration between stimulus pulses. Uptake is found to be described by a constant set of Michaelis-Menten kinetics at each location for concentrations of dopamine from 100 nM to 15 microM. The concentration of dopamine released per stimulus pulse is found to be greatest at low frequency (< or = 10 Hz) with stimulus trains, and with single-pulse stimulations in nomifensine-treated animals. The frequency dependence of release is not an effect of dopamine receptor activation; haloperidol (2.5 mg/kg) causes a uniform increase in release at all frequencies. The absence of diffusional effects in the measurement locations means that the constants determined with the electrode are those operant inside intact striatal tissue during stimulated overflow. These values are then extrapolated to the case where a single neuron fires alone. The extrapolation shows that while the transient concentration of dopamine may be high (200 nM) at the interface of the synapse and the extrasynaptic region, it is normally very low (< 6 nM) in the bulk of extracellular fluid.

Effect of chronic haloperidol treatment on stimulated synaptic overflow of dopamine in the rat striatum.

In vivo voltammetry was used to assess the change in stimulated striatal dopamine overflow in response to various treatments with the dopamine receptor antagonist haloperidol. Dopamine overflow was induced with stimulating electrodes implanted in the medial forebrain bundle of anesthetized rats while dopamine concentrations were monitored with Nafion-coated, carbon-fiber microelectrodes implanted in the striatum. An acute challenge of haloperidol (0.5 mg kg-1, i.p.) given to naive animals caused stimulated overflow to increase at all stimulation frequencies (10-60 Hz), with the greatest change, 5-fold, occurring at 30 Hz. These results have been compared to those obtained in a different group of rats given daily injections of haloperidol (0.5 mg kg-1, s.c.) for 30 consecutive days. On the 30th day, dopamine striatal tissue levels and uptake kinetics were not altered by this treatment, but 3,4-dihydroxyphenylacetic acid tissue levels were elevated almost 2-fold. A challenge dose of haloperidol (0.5 mg kg-1, i.p.) administered to the animals treated with chronic haloperidol did not elicit a change in stimulated dopamine overflow. In two other groups, rats were withdrawn from 30-day haloperidol treatment for 3 days or 14 days before experimentation. Stimulated dopamine overflow concentrations in both groups were not significantly different from naive animals. When the withdrawn animals were given a haloperidol challenge (0.5 mg kg-1, i.p.), 15- and 12-fold increases in overflow for 3-day and 14-day withdrawal groups, respectively, were observed at a stimulation frequency of 30 Hz. Thus, chronic treatment with haloperidol induces long-lasting effects on the capacity of dopamine receptors to modulate dopamine release.

Strategies for low detection limit measurements with cyclic voltammetry.

Cyclic voltammetry of Nafion-coated, carbon-fiber electrodes is used to detect trace concentrations of dopamine, both in a flow injection apparatus and in the brain of an anaesthetized rat. To improve signal-to-noise ratios, the sources of noise during cyclic voltammetry have been determined and strategies have been developed to decrease the noise. With the potentiostat employed, the measured noise is comparable to that expected for Johnson noise from the feedback resistor of the current transducer. Additional noise arises from the waveform generator employed and, in some cases, line noise. Line noise is discriminated against by starting each cyclic voltammogram either in phase or 180 degrees out of phase with the line frequency. When used in vivo, additional noise also arises from the physiological activity of the animal. Detection limits are found to closely correspond to those predicted on the basis of simulation of the voltammetric shape and the measured noise. Detection limits are improved by the use of appropriate analog and digital filtering, ensemble averaging, and appropriate timing of repetitive cyclic voltammograms. The combined use of these techniques enables the in vivo detection of approximately 100 nM of dopamine with a signal-to-noise ratio of 25.

Interference by DOPAC and ascorbate during attempts to measure drug-induced changes in neostriatal dopamine with Nafion-coated, carbon-fiber electrodes.

The selectivity of Nafion-coated, carbon-fiber electrodes was evaluated for the voltammetric detection of dopamine in the presence of 3,4-dihydroxyphenylacetic acid (DOPAC) and ascorbate, which are interferant anions in the brain. Nafion coating was applied to both polished carbon-disk electrodes and electrochemically modified electrodes. During in vitro testing, polished disk electrodes showed the greatest selectivity for dopamine at the fastest scan rate tested (300 V s-1), but the drift in signal made slow changes in dopamine difficult to determine. Electrochemically modified electrodes already provide an ascorbate wave distinct from that for dopamine, but Nafion coating actually decreased dopamine selectivity with respect to DOPAC. In vivo testing was carried out in the neostriatum of urethane-anesthetized rats in response to drug- or stimulation-induced increases in dopamine transmission. Administration of haloperidol (0.5 mg kg-1) followed by GBR 12909 (20 mg kg-1), which is known to cause a 10-fold increase in extracellular dopamine, failed to produce a selective signal for dopamine when measured voltammetrically. Comparable results were obtained following administration of amphetamine (2.5 mg kg-1), which also increases dopamine overflow. Voltammetric detection of dopamine was possible, however, during electrical stimulation of dopaminergic afferents in the medial forebrain bundle. Thus, voltammetry with Nafion-coated electrodes is best suited to the measurement of transient changes in extracellular dopamine rather than the relatively prolonged changes in dopamine overflow produced by various drugs.

[The functional efficiency of cardiac pacemakers as affected by ionizing radiation]. / Untersuchungen zur Funktionstüchtigkeit von Herzschrittmachern unter dem Einfluss ionisierender Strahlung.

Influence of functions of cardiac pace-makers by ionizing radiation are represented, that is characterized in praxis relevant parameters as pulse duration and sensitivity in a special clear manner. For these parameters dose limits were defined in a phantom where tolerance ranges of pace-makers, guaranteed by producer, were over or underdosed. These dose values were different in dependence of installed electronic wiring diagrams. The radioresistance of pace-makers with Lewicki-wiring diagram (MCP 211 L) was higher than those with wiring diagram U 115. Measurings showed that the upper dose limits were greater than the known values with 60Co- and 9-MV-roentgen braking radiation and with that the complete programming and functional capacity of the pace-makers were conserved. The close cooperation of radiologists, physicists, cardiologists and technicians in the implantation clinic guarantees a good care for patients with pace-makers during radiotherapy without complications.

[Biological VA cross talk in an AAJ pacemaker]. / Biologisches VA-cross-talk bei einem AAJ-Schrittmacher.

On the basis of an observation in a female patient with atrial pacemaker the complication of the "cross-talk" phenomenon is explained, which up to now has been known above all in two-chamber pacemakers. The typical manifestation of ECG of the cross-talk is the change of the stimulation frequency or the total inhibition of the ventricular impulse output in DDD-pacemakers. Attention is paid to the importance of this phenomenon which increases in our country with growing number of the implanted two-chamber pacemakers.

[Modification of cardiac pacemakers of the MCP and LCP series by electrodiagnostic and electrotherapy procedures]. / Beeinflussung von Herzschrittmachern der MCP- und LCP-Serie durch Elektrodiagnostik- und Elektrotherapieverfahren.

47 patients with cardiac pacemakers of the MCP- and LCP-series were examined for influence by disturbances caused by devices of electrodiagnostics and electrotherapy used in the GDR. A general prohibition of such diagnostic and therapeutic methods cannot be maintained. Low frequency current therapy (apart from TENS-currents), hydrogalvanic baths and ultrasonic therapy could be applied without any danger. In the CP-current should be guaranteed a minimum distance of 50 cm, when it fell short of, however, only insignificant disturbances appeared. The same concerns the microwave therapy. Also electrodiagnostics was possible without endangering the pacemaker-patient. TENS-currents caused, depending on distance and frequency, no disturbances or dangerous ones (total inhibition). Short-wave repeatedly led to total inhibition or warming at the cardiac pacemaker and should therefore generally be forbidden.