6,333 research outputs found
Radiotelemetry monitored measurements of the effects of medetomidine-midazolam-fentanyl, isoflurane or ketamine-xylazine anaesthesia on physiological parameters in guinea pigs
Anaesthesia in guinea pigs (GPs) has often been described as difficult and risky. Therefore, the included publications invested the effect of the mostly used anaesthesias MMF (medetomidine-midazolam-fentanyl), isoflurane (Iso) and ketamine-xylazine (KX) on physiological parameters in GPs. Throughout the anaesthesia, the GPs cardiovascular parameters were monitored, using abdominally implanted radiotelemetry devices to obtain optimal data quality.
The surgical approach used for the implantation of the radiotelemetry transmitter is presented in detail in the first publication. For surgery, the GPs were anaesthetised with MMF (medetomi-dine-midazolam-fentanyl) and they were antagonised with AFN (atipamezole-flumazenil-nalxone) at the end of the surgery. For pain medication, the GPs were started on meloxicam (0.4 mg/kg) and metamizole (80 mg/kg) 30 min before the surgery. Metamizole was continued for 24 h after surgery and meloxicam for 2 more days. During the implantation, they were additionally covered with the fentanyl component in MMF. Prior to the surgery, enrofloxacin (10 mg/kg) was applied for antibiotic coverage which was continued for 2 more days. Using the implanted system, arterial blood pressure (BP), heart rate (HR) and core body temperature (BT) were measured throughout the first 24 h after the end of the implantation. The implantation approach led to the highest long-term survival rate reported to date, with 13 of 16 GPs (81 %) surviving. The GPs lost body weight (BW) until 2 d after surgery (-11.9 %, -53.6 g) but steadily increased their weight thereafter. The GPs had returned to physiological values in BP and BT at 8 h after abdominal surgery and at 24 h regarding HR. As GPs are stress-prone, recommendations for stress reduced handling were given for before, during and after the implantation. The findings on the effects of the implantation can be used as a model for other abdominal operations in the GP.
The second publication described the investigation of the effects of one-time Iso, MMF and KX anaesthesia on the physiological parameters using the 13 implanted GPs. Each animal was anesthetised once with MMF, Iso and KX at an interval of 7 d. The entire anaesthesia pass was recorded radiotelemetrically and supplemented by manual measurements of respiratory rate (ReR), reflexes and blood glucose (BG). One anaesthesia pass included 120 min acclimatization time, of which the last 15 min were averaged as individual baseline values. The GPs were then premedicated; with Iso with atropine and with MMF and KX with sodium chloride as placebo. Ten minutes later, anaesthesia was initiated, for Iso anaesthesia using a pre-filled whole body chamber and for MMF and KX with intramuscular injections into the hind limbs. Anaesthesia was discontinued after 40 min by Iso supply stop, AFN antagonisation for MMF or partial antagonisation with atipamezole for KX anaesthesia. The MAP, HR, BT were measured continuously until at least 240 min after anaesthesia induction. Respiratory rate (ReR) was measured until at least 55 min and reflexes were tested until the GPs showed a positive righting reflex again. BG values were measured at 7.5, 20 and 40 min during anaesthesia.
With Iso use, all GPs reached a surgical tolerance, 11 did so with MMF anaesthesia and only 7 reached an operable state with KX. The induction, non-surgical tolerance and surgical tolerance phase durations did not differ considerably between the 3 anaesthetics. Following MMF and Iso there were short wake-up times (7.6 & 12.2 min), whereas it required 59.7 min until the GPs regained their RR after KX. MMF anaesthesia led to a marked transient MAP decrease after antagonisation, otherwise the MAP and the HR were only mildly altered. Iso exposure led to a marked hypotension during anaesthesia maintenance (approx. 20 mmHg) and the HR was only mildly increased at the beginning of the anaesthesia. KX caused mild deviations from the normal physiology for MAP and HR during maintenance. However, after partial antagonisation, the MAP dropped and the GPs recovered only slowly. The HR was also reduced and increased only gradually during the wake-up following KX anaesthesia.
All anaesthetics induced hypothermia, but the animals lost the most BT with Iso anaesthesia. Immediately after the end of the MMF and Iso anaesthesia, the GPs were able to quickly lift their BT back to the starting level through shivering. After KX anaesthesia only 3 of the 7 GPs had returned to 38.8°C after 5 h, the other 4 still had not reached pre-anaesthetic BT values after 8 h. Respiratory depression occurred with all 3 anaesthetics, with KX leading to a moderate (-52%) and Iso to a severe (-71%) hypoventilation. There was also a strong irritation of the mucous membranes of the respiratory tract through the respiratory gas. Subsequent mucosal secretion could only be alleviated by atropine pre-medication in the short term. BG increases were observed during KX (moderate) and strongly during MMF anaesthesia. The reflex responses varied considerably between the anaesthetics. They were strong and quick during MMF anaesthesia and slightly less so with KX use. Iso exposure led to weak and slow reflex responses. Overall, MMF was determined to be the anaesthesia of choice; Iso can only be advised for short and non-painful procedures and we advise against the use of KX anaesthesia in GPs.
After investigating the effects of single anaesthesia with Iso, MMF and KX, the third paper de-scribed the impact of repeated MMF and Iso anaesthesia. KX was not tested for anaesthesia repetition because of its highly unfavourable effects in the recovery phase. Twelve instrumented MS were anesthetised in 2 anaesthesia sets, 6 times over 3 weeks with either only Iso or only MMF. Each anaesthesia repetition was performed as described for the single anaesthesia.
All GPs reached a surgical tolerance and this could be maintained for the desired 40 min. Overall, the anaesthetic profiles of MMF and Iso did not change greatly with anaesthesia repetition.
During Iso exposure, the repeated atropine premedication caused the HR to increase, and this increase remained longer with progressing repetitions. During MMF the wake-up phase short-ened from the 1st to the 2nd repetition and the MAP and the HR decreased from the first to all following anaesthesias. During the MMF maintenance, there was a large individual variation in the BP between the GPs, but the single animal always exhibited similar MAP values during all of the repetitions. At 40 min of the MMF anaesthesia, the BG had increased particularly strongly in those anaesthesias that were performed with an interval of 2 d.
The BT decrease and the BW increase were not altered. Both anaesthetics can therefore be used repeatedly in the GP with very little change in the anaesthesia profile compared to the single anaesthesias. The GPs developed increasingly stronger defensive reactions which were particularly pronounced with Iso. They reduced the reliability with which the injections of MMF and atropine could be performed and with that the induction of anaesthesia. Although repeated Iso anaesthesia led to lesser repetition-related effects, the highly disadvantageous effects of hypotension, mucous production and hypoventilation with Iso anaesthesia remained and were further worsened by the strong defensive reactions. MMF led to a much more beneficial anaesthesia with the only drawback of altering the BG and the occurring hypothermia. In conclusion, MMF is superior for both single and repeated anaesthesia use in the GP. Iso is only preferable to MMF, if multiple anaesthesias need to be performed on the same day.Die AnĂ€sthesie an Meerschweinchen (MS) wurde schon oft als schwierig und risikoreich be-schrieben. Mit diesem Hintergrund wurden die drei hĂ€ufigsten Narkosemittel, Medetomidin-Midazolam-Fentanyl (MMF), Isofluran (Iso) und Ketamin-Xylazin (KX), hinsichtlich ihres Einflusses auf die physiologischen Parameter im MS untersucht. Die Ăberwachung vor, wĂ€hrend und nach den AnĂ€sthesien wurde durch einen abdominal implantierten Radiotelemetriesender durchgefĂŒhrt.
In der ersten Publikation wurde die Implantation des Telemetriesenders detailliert dargestellt. FĂŒr den Eingriff wurden die MS mit MMF anĂ€sthesiert und die Narkose wurde am Ende des Eingriffes mit AFN (Atipamezol- Flumazenil-Naloxon) wieder aufgehoben. Die Analgesie bestand aus Meloxicam (0,4 mg/kg) und Metamizol (80 mg/kg), womit 30 Minuten vor dem Start der Operation begonnen wurde. WĂ€hrend der AnĂ€sthesie wurde die Analgesie zusĂ€tzlich ĂŒber die Fentanyl Komponente des MMFs erhalten. Nach der Implantation wurde Metamizol fĂŒr 24 Stunden und Meloxicam fĂŒr 48 h fortgesetzt. Zur antibiotischen Versorgung erhielten die MS Enrofloxacin (10 mg/kg) vor dem Beginn der Operation und in den zwei darauffolgenden Tagen. Unter Verwendung des implantierten Senders wurden der arterielle Blutdruck (BD), die Herzfrequenz (HF) und die Kernkörpertemperatur (KT) in den ersten 24 h nach dem Ende der Implantation gemessen. Die durchgefĂŒhrte Implantationsherangehensweise fĂŒhrte zu der bisher höchsten publizierten LangzeitĂŒberlebensrate mit 13 von 16 Tieren (81%). Bis 2 Tage nach der Operation verloren die Tiere an Körpergewicht (-11,9 %, -53,6 g). Danach stieg ihr Gewicht jedoch stetig wieder an. Die MS waren nach 8 h nach ihrer abdominalen Operation zu physiologischen Werten in Blutdruck und Körperkerntemperatur und nach 24 h zu normalen HF zurĂŒckgekehrt. Aufgrund der hohen StressanfĂ€lligkeit von MS, wurden Empfehlungen fĂŒr stressarmes Handling, fĂŒr vor, wĂ€hrend und nach der Implantation gegeben. Die Erkenntnisse ĂŒber die Auswirkungen der Implantation können modelhaft auf andere Bauchoperationen im MS angewendet werden.
Die zweite Veröffentlichung beschrieb die Untersuchung der Wirkungen von einmaligen Iso, MMF und KX AnĂ€sthesien auf die physiologischen Parameter unter Verwendung der 13 implan-tierten MS. Jedes Tier wurde einmalig mit MMF, Iso und KX im Abstand von 7 d anĂ€sthesiert. Der gesamte AnĂ€sthesiedurchgang wurde radiotelemetrisch aufgezeichnet und durch manuelle Erhebungen fĂŒr Atemfrequenz (AF), Reflexe und Blutglukose (BG) ergĂ€nzt. Ein AnĂ€sthesiedurch-gang beinhaltete 120 min Akklimatisierungszeit, wovon die letzten 15 min als individuelle Baselinewerte gemittelt wurden. Danach wurden die MS prĂ€mediziert; bei Iso mit Atropin und bei MMF und KX mit Natriumchlorid als Placebo. Zehn min spĂ€ter wurde die AnĂ€sthesie eingeleitet mit einer vorgefluteten Ganzkörperkammer fĂŒr die Iso AnĂ€sthesie und fĂŒr MMF und KX mit intramuskulĂ€ren Injektionen in die HintergliedmaĂen. Die AnĂ€sthesie wurde fĂŒr nach 40 min aufgehoben durch Iso-zufuhrstopp, AFN Antagonisierung oder Teilantagonisierung mit Atipamezol. Der BD, die HF, und die KT wurden kontinuierlich bis mindestens 240 min nach AnĂ€sthesieeinleitung gemessen. Die AF wurde bis mindestens 55 min gemessen, und die Reflexe wurden bis zum Erreichen eines positiven Stellreflexes getestet. Bei 7,5, 20 und 40 min wĂ€hrend der AnĂ€sthesie wurden BG Werte erhoben.
Mit der Anwendung von Iso erreichten alle MS eine chirurgische Toleranz, mit der MMF-AnĂ€sthesie waren es 11 MS und nur 7 erreichten einen operablen Zustand mit KX. Die Induktion, nicht-chirurgische Toleranz und chirurgische Toleranzphasendauer unterschieden sich nicht erheblich zwischen den 3 AnĂ€sthetika. Auf die Narkosen mit MMF und Iso folgten kurze Weckzeiten (7,6 & 12,2 min), wĂ€hrend es 59,7 min benötigte, bis die MS ihren RR nach KX wiedererlangten. Die MMF-AnĂ€sthesie fĂŒhrte zu einer kurzen, deutlichen BD-Abnahme nach Antagonisierung, ansonsten wurden der BD und der HF nur geringfĂŒgig verĂ€ndert. Die Iso-Exposition fĂŒhrte zu einer ausgeprĂ€gten Hypotonie wĂ€hrend der AnĂ€sthesieerhaltung (ca. 20 mmHg) und die HF war zu Beginn der AnĂ€sthesie nur leicht erhöht. KX verursachte nur milde Abweichungen von der normalen Physiologie fĂŒr BD und HF wĂ€hrend der AnĂ€sthesieerhaltung. Nach der Teilantagonisierung fiel der BD die HF und die KT jedoch ab und die MS erholten sich nur langsam.
Alle AnĂ€sthetika induzierten eine Hypothermie, aber unter der Iso Narkose verloren die MS am schnellsten und am meisten Körpertemperatur. Direkt nach dem Ende der MMF- und Iso-Narkose konnten sie ihre KT ĂŒber KĂ€ltezittern schnell wieder auf das Ausgangslevel heben. Nach der KX-AnĂ€sthesie waren jedoch nur 3 der 7 GPs auf 38,8 ° C KT zurĂŒckgekehrt, die anderen 4 hatten auch nach 8 h noch nicht wieder ihre Ausgangskörperkerntemperatur erreicht. Eine Atemdepression trat bei allen 3 Narkosemitteln auf, am ausgeprĂ€gtesten jedoch unter der Iso-Narkose (-71%). Dort trat zusĂ€tzlich eine starke Reizung der SchleimhĂ€ute der Atemwege durch das Atemgas auf. Die nachfolgende Schleimsekretion konnte durch die AtropinprĂ€medikation nur kurzfristig gelindert werden. Der BG-Spiegel stieg wĂ€hrend der AnĂ€sthesie mit KX (mĂ€Ăig) und wĂ€hrend der MMF-AnĂ€sthesie stark an. Die Reflexantworten variierten erheblich zwischen den AnĂ€sthetika. Sie waren stark und schnell wĂ€hrend der MMF AnĂ€sthesie und etwas weniger deutlich ausgeprĂ€gt unter der KX-Anwendung. Die Iso-Exposition fĂŒhrte hingegen zu schwachen und langsamen Reflexantworten. Insgesamt ist MMF die AnĂ€sthesie der Wahl beim MS; Iso sollte nur fĂŒr kurze und nicht schmerzhafte Verfahren beraten werden und wir empfehlen die Verwendung von KX AnĂ€sthesie bei GPs.
Nach der Untersuchung der EinzelanĂ€sthesieffekte mit Iso, MMF und KX, beschrieb die dritte Publikation die Auswirkungen der wiederholten MMF- und Iso-AnĂ€sthesie. Aufgrund der deutli-chen Nachtteile der KX-Narkose in der Aufwachphase wurde KX von der Wiederholungsstudie ausgeschlossen. Zwölf instrumentierte MS wurden in 2 AnĂ€sthesiesets jeweils 6 mal ĂŒber 3 Wo-chen mit entweder nur Iso oder nur MMF anĂ€sthesiert. Der Aufbau der einzelnen AnĂ€sthesie-durchgĂ€nge war derselbe wie bei in EinzelanĂ€sthesien beschrieben. Alle GPs erreichten eine chirurgische Toleranz, und diese konnte fĂŒr die gewĂŒnschten 40 min aufrechterhalten werden. Insgesamt Ă€nderten sich die AnĂ€sthesieprofile von MMF und Iso nur sehr gering im Verlauf der AnĂ€sthesiewiederholung. Durch die wiederholte AtropinprĂ€medikation nahm die HF zu und dieser Anstieg blieb mit fortschreitenden Wiederholungen immer lĂ€nger bestehen. Bei der MMF AnĂ€sthesie verkĂŒrzte sich die Aufwachzeit vor allem von der 1. auf die 2. Wiederholung. Der BP und die HF nahmen nach der ersten Wiederholung fĂŒr die nachfolgenden AnĂ€sthesien ab. WĂ€hrend der MMF-AnĂ€sthesieerhaltung zeigten die MS groĂe individuelle Variationen im BD. Jedes einzelne Tier blieb jedoch wĂ€hrend allen Wiederholungen auf seinem eigenen Niveau. Die BG war bei den MMF-AnĂ€sthesien zwischen denen nur 2 Tage lagen 40 min nach der AnĂ€sthesieeinleitung besonders hoch. Die KT-Abnahme trat sowohl bei MMF, als auch bei Iso wĂ€hrend der AnĂ€sthesie auf und die Körpergewichtsentwicklung verĂ€nderte sich durch die Wiederholungen nicht.
Sowohl Iso als auch MMF können nach diesen Ergebnissen daher wiederholt in MS eingesetzt werden. Trotzdem entwickelten die MS zunehmend stĂ€rkere Abwehrreaktionen gegen die AnĂ€s-thesieeinleitung, die bei Iso besonders ausgeprĂ€gt waren. Sie reduzierten die ZuverlĂ€ssigkeit, mit der die Injektionen von MMF und Atropin durchgefĂŒhrt werden konnten und damit die Induktion der AnĂ€sthesie. Die Iso-AnĂ€sthesie fĂŒhrte zwar zu geringeren Wiederholungswirkungen im Vergleich zu MMF, das AnĂ€sthesieprofil mit der starken Atemdepression und Schleimproduktion und der starken Hypotension bestand jedoch weiterhin. Insgesamt sind die Effekte der Wiederholungen bei der MMF AnĂ€sthesie weitgehend vernachlĂ€ssigbar und das AnĂ€sthesieprofil ist wesentlich vorteilhafter fĂŒr die MS. Daher ist MMF fĂŒr die einfache und wiederholte AnĂ€sthesie im MS das AnĂ€sthetikum der Wahl, es sei denn am selben Tag mĂŒssen mehrere AnĂ€sthesien durchgefĂŒhrt werden mĂŒssen. In dem Fall ist Iso vorzuziehen
Multi-spin dynamics of the solid-state NMR Free Induction Decay
We present a new experimental investigation of the NMR free induction decay
(FID) in a lattice of spin-1/2 nuclei in a strong Zeeman field. Following a
pi/2 pulse, evolution under the secular dipolar Hamiltonian preserves coherence
number in the Zeeman eigenbasis, but changes the number of correlated spins in
the state. The observed signal is seen to decay as single-spin, single-quantum
coherences evolve into multiple-spin coherences under the action of the dipolar
Hamiltonian. In order to probe the multiple-spin dynamics during the FID, we
measured the growth of coherence orders in a basis other than the usual Zeeman
eigenbasis. This measurement provides the first direct experimental observation
of the growth of coherent multiple-spin correlations during the FID.
Experiments were performed with a cubic lattice of spins (19F in calcium
fluoride) and a linear spin chain (19F in fluorapatite). It is seen that the
geometrical arrangement of the spins plays a significant role in the
development of higher order correlations. The results are discussed in light of
existing theoretical models.Comment: 7 pages, 6 figure
The Prevalence of Pain in Patients Attending Sarcoma Outpatient Clinics
The prevalence of pain in patients with sarcoma is not well documented. We investigated this in outpatients at a tertiary cancer referral centre, assessing the adequacy of pain control and for risk factors leading to higher prevalence and severity of pain. 149 patients were surveyed. Patients with pain within the previous 7 days completed pain assessment tools (BPI, S-LANSS, PMI). 53% of patients had pain within the previous 7 days, and 25% had significant pain. Of those with pain, 63% was inadequately controlled and neuropathic pain was identified in 36%. Age, gender, tumour type, and the type of cancer treatment were not significant predictors of the prevalence or severity of the pain. Based on our results, patients with sarcoma should be actively screened for pain and have regular reviews of their analgesic requirements
Parity Violation in 232Th Neutron Resonances Above 250 eV
The analysis of parity nonconservation (PNC) measurements performed on 232Th by the TRIPLE Collaboration has been extended to include the neutron energy range of 250 to 1900 eV. Below 250 eV all ten statistically significant parity violations have the same sign. However, at higher energies PNC effects of both signs were observed in the transmission of longitudinally polarized neutrons through a thick thorium target. Although the limited experimental energy resolution precluded analysis in terms of the longitudinal asymmetry, parity violations were observed and the cross section differences for positive and negative neutron helicities were obtained. For comparison, a similar analysis was performed on the data below 250 eV, for which longitudinal asymmetries were obtained previously. For energies below 250 eV, the p-wave neutron strength functions for the J=1/2 and J=3/2 states were extracted: S1/21=(1.68±0.61)Ă10-4 and S3/21=(0.75±0.18)Ă10-4. The data provide constraints on the properties of local doorway states proposed to explain the PNC sign effect in thorium
Search for Parity Violation in 93Nb Neutron Resonances
A new search has been performed for parity violation in the compound nuclear states of 94Nb by measuring the helicity dependence of the neutron total cross section. Transmission measurements on a thick niobium target were performed by the time-of-flight method at the Manuel Lujan Neutron Scattering Center with a longitudinally polarized neutron beam in the energy range 32 to 1000 eV. A total of 18 p-wave resonances in 93Nb were studied with none exhibiting a statistically significant parity-violating longitudinal asymmetry. An upper limit of 1.0Ă10-7 eV (95% confidence level) was obtained for the weak spreading widthÎw in 93Nb
Parity Violation in Neutron Resonances in 107,109Ag
Parity nonconservation (PNC) was studied in p-wave resonances in Ag by measuring the helicity dependence of the neutron total cross section. Transmission measurements on natural Ag were performed in the energy range 32 to 422 eV with the time-of-flight method at the Manuel Lujan Neutron Scattering Center at Los Alamos National Laboratory. A total of 15 p-wave neutron resonances were studied in 107Ag and ninep-wave resonances in 109Ag. Statistically significant asymmetries were observed for eight resonances in 107Ag and for four resonances in109Ag. An analysis treating the PNC matrix elements as random variables yields a weak spreading width of Îw=(2.67-1.21+2.65)Ă10-7âeV for107Ag and Îw=(1.30-0.74+2.49)Ă10-7âeV for 109Ag
Hippocampal internal architecture and postoperative seizure outcome in temporal lobe epilepsy due to hippocampal sclerosis
AbstractPurposeSemi-quantitative analysis of hippocampal internal architecture (HIA) on MRI has been shown to be a reliable predictor of the side of seizure onset in patients with temporal lobe epilepsy (TLE). In the present study, we investigated the relationship between postoperative seizure outcome and preoperative semi-quantitative measures of HIA.MethodsWe determined HIA on high in-plane resolution preoperative T2 short tau inversion recovery MR images in 79 patients with presumed unilateral mesial TLE (mTLE) due to hippocampal sclerosis (HS) who underwent amygdalohippocampectomy and postoperative follow up. HIA was investigated with respect to postoperative seizure freedom, neuronal density determined from resected hippocampal specimens, and conventionally acquired hippocampal volume.ResultsHIA ratings were significantly related to some neuropathological features of the resected hippocampus (e.g. neuronal density of selective CA regions, Wyler grades), and bilaterally with preoperative hippocampal volume. However, there were no significant differences in HIA ratings of the to-be-resected or contralateral hippocampus between patients rendered seizure free (ILAE 1) compared to those continuing to experience seizures (ILAE 2-5).ConclusionsThis work indicates that semi-quantitative assessment of HIA on high-resolution MRI provides a surrogate marker of underlying histopathology, but cannot prospectively distinguish between patients who will continue to experience postoperative seizures and those who will be rendered seizure free. The predictive power of HIA for postoperative seizure outcome in non-lesional patients with TLE should be explored
Parity Violation in Neutron Resonances in 115In
Parity nonconservation (PNC) was studied in p-wave resonances in indium by measuring the helicity dependence of the neutron total cross section in the neutron energy range 6.0â316 eV with the time-of-flight method at LANSCE. A total of 36 p-wave neutron resonances were studied in 115In, and statistically significant asymmetries were observed for nine cases. An analysis treating the PNC matrix elements as random variables yields a weak matrix element of M=(0.67-0.12+0.16)âmeV and a weak spreading width of Îw=(1.30-0.43+0.76)Ă10-7âeV
Observation of a large parity nonconserving analyzing power in Xe
A large parity nonconserving longitudinal analyzing power was discovered in polarized-neutron transmission through Xe. An analyzing power of 4.3±0.2% was observed in a p-wave resonance at En=3.2 eV. The measurement was performed with a liquid Xe target of natural isotopic abundance that was placed in the polarized epithermal neutron beam, flight path 2, at the Manuel Lujan Neutron Science Center. This apparatus was constructed by the TRIPLE Collaboration, and has been used for studies of parity symmetry in compound nuclear resonances. Part of the motivation of the experiment was to discover a nucleus appropriate for a sensitive test of time-reversal invariance in polarized-neutron transmission. The large analyzing power of the observed resonance may make it possible to design a test of time reversal invariance using a polarized-Xe target
- âŠ