Does anesthesia duration or number of cases per patient predict safety events?

BACKGROUND: The need for dental rehabilitation under general anesthesia is increasing, with varying needs between patients. Mortality has been found to be a rare event in these patients; however other perioperative events can and do occur. Previous studies have established increased incidence of perioperative events with younger, sicker children, and longer anesthetics, however, no studies to date have evaluated if the incidence of perioperative events is more closely associated with one long anesthetic or multiple anesthetics per patient. AIMS: To evaluate the association of perioperative events related to single anesthetic duration or number of anesthetics per patient for dental rehabilitation. METHODS: After Children's Wisconsin Human Research Protection Program determined this quality activity did not meet the definition of human subjects research, we performed an epidemiologic observational evaluation by extracting all dental related cases (dental alone or with oral surgeon vs. dental with other specialties) with an associated general anesthesia encounter from Children's Wisconsin electronic data warehouse from June 1, 2015 to December 31, 2021. These cases occurred at a free-standing children's hospital or associated pediatric-only ambulatory surgery center. The risk of perioperative safety events was analyzed for previously identified risk groups such as American Society of Anesthesiologists Physical Status (ASA-PS), patient age, anesthesia case time with the addition of number of dental cases per patient. RESULTS: In this study, 8468 procedures were performed on 8082 patients. Of this cohort, 7765 patients underwent one procedure for dental care while 317 patients underwent a total of 703 dental-related procedures, ranging from two to five procedures per patient. Multivariable logistic regression identified increased risk of perioperative events in patients with ASA-PS 3 (n = 1459, rate 1.78%, p value .001, OR 5.7, CI 2.1-15.5) and ASA-PS 4 (n = 86, rate 5.8%, p < .001, OR 17.2, CI 4.4-67.3), anesthesia duration (p < .001, OR 1.46, CI 1.21-1.76), but no increased risk with number of anesthetics per patient (p value .54, OR 0.81, CI 0.4-1.61). CONCLUSIONS: Limiting dental care under general anesthesia to multiple short cases may decrease the risk of perioperative events when compared to completing all treatment in one long operative session.

Evidence that errors made by DNA polymerase alpha are corrected by DNA polymerase delta.

Eukaryotic replication begins at origins and on the lagging strand with RNA-primed DNA synthesis of a few nucleotides by polymerase alpha, which lacks proofreading activity. A polymerase switch then allows chain elongation by proofreading-proficient pol delta and pol epsilon. Pol delta and pol epsilon are essential, but their roles in replication are not yet completely defined . Here, we investigate their roles by using yeast pol alpha with a Leu868Met substitution . L868M pol alpha copies DNA in vitro with normal activity and processivity but with reduced fidelity. In vivo, the pol1-L868M allele confers a mutator phenotype. This mutator phenotype is strongly increased upon inactivation of the 3' exonuclease of pol delta but not that of pol epsilon. Several nonexclusive explanations are considered, including the hypothesis that the 3' exonuclease of pol delta proofreads errors generated by pol alpha during initiation of Okazaki fragments. Given that eukaryotes encode specialized, proofreading-deficient polymerases with even lower fidelity than pol alpha, such intermolecular proofreading could be relevant to several DNA transactions that control genome stability.

Temporal profile of connexin 43 expression after photothrombotic lesion in rat brain.

Following focal ischemic injury, several mechanisms lead to secondary expansion of the affected area and therefore increase the initial damage. We thoroughly investigated the expression of astrocytic connexin 43 (Cx43) after photothrombosis in rat brain. The temporal profile of Cx43 mRNA as well as protein expression was studied in remote, structurally uninjured cortical and hippocampal areas. The hippocampal formation revealed an increased number of Cx43 mRNA positive astrocytes and an up-regulated protein expression exclusively in the ipsilateral stratum oriens. We assume a participation of this region in glia scar formation. While Cx43 mRNA positive cells were transiently increased, immunoreactivity was reduced in the somatosensory cortex of injured hemispheres. The observed decrease of Cx43 protein in the post-ischemic cerebral cortex implies an impairment of gap junctional intercellular communication which might be detrimental to the brain.

Stable expression of the vesicular GABA transporter following photothrombotic infarct in rat brain.

Before exocytotic release of the inhibitory neurotransmitter GABA, this amino acid has to be stored in synaptic vesicles. Accumulation of GABA in vesicles is achieved by a specific membrane-integrated transporter termed vesicular GABA transporter. This vesicular protein is mainly located at presynaptic terminals of GABAergic interneurons. In the present study we investigated the effects of focal ischemia on the expression of the vesicular GABA transporter. Vesicular GABA transporter mRNA and protein expression was examined after photothrombosis in different cortical and hippocampal brain regions of Wistar rats. In situ hybridization and quantitative real-time RT-PCR were performed to analyze vesicular GABA transporter mRNA. Both vesicular GABA transporter mRNA-stained perikarya and mRNA expression levels remained unaffected. Vesicular GABA transporter protein-containing synaptic terminals and somata were visualized by immunohistochemistry. The pattern of vesicular GABA transporter immunoreactivity as well as the protein expression level revealed by semiquantitative image analysis and by Western blot remained stable after stroke. The steady expression of vesicular GABA transporter mRNA and protein after photothrombosis indicates that the exocytotic release mechanism of GABA is not affected by ischemia.

GABA neurons survive focal ischemic injury.

Focal cerebral lesions in rat brain induced by photothrombosis lead to an impaired inhibitory neurotransmission. A reduced gamma-aminobutyric acid (GABA)-mediated inhibition has been revealed by electrophysiological recordings associated with a diminished immunostaining of GABA handling proteins. Changes were found in ipsi- as well as in contralateral brain areas. Inhibition is mediated by interneurons using GABA as neurotransmitter. These cells use GAD (glutamate decarboxylase) to synthesize GABA. To analyze the vulnerability of GABAergic neurons in rats with a lesioned hindlimb area, cells expressing GAD65/67 mRNA were labeled using in situ hybridization. Positive somata were counted 7 and 30 days after focal ischemia in different cortical (hindlimb cortex, frontal cortex, primary and secondary somatosensory cortex) and hippocampal subsectors (pyramidal cell layer, stratum oriens and stratum radiatum/lacunosum-moleculare). The lesioned hemispheres were compared with the intact brain sides and with control brains. GABAergic interneurons survived the injury for up to 30 days in all investigated brain regions. Therefore it is unlikely that a loss of GABAergic neurons contributes to the reduced inhibition.

Efficacy of background GABA uptake in rat hippocampal slices.

GABA uptake is crucial for the termination of inhibitory synaptic events. In addition, GABA transporters may also control the level of diffusely distributed GABA in the extracellular space. We analysed this function by superfusing rat hippocampal slices with different concentrations of GABA. Whole-cell patch clamp recordings of CA1 pyramidal cells revealed small increases in chloride conductance at 5-10 microM GABA which increased dramatically upon addition of the GABA uptake blocker tiagabine. Tiagabine alone induced a significant chloride conductance indicating that spontaneous release of GABA in hippocampal slices is neutralized by GAT-1, the main hippocampal GABA transporter. Thus, GAT-1 clears the extracellular space in the hippocampus from diffusely distributed GABA with high efficacy.

Age-dependence of the anticonvulsant effects of the GABA uptake inhibitor tiagabine in vitro.

Epileptic syndromes frequently start at childhood and therefore it is crucial to test new anticonvulsants at immature stages of the nervous system. We compared the effects of the gamma-aminobutyric acid (GABA) uptake inhibitor tiagabine [(R)-N-(4, 4-bis(3-methyl-2-thienyl)but)3-en-1-yl nipecotic acid] on low-Mg(2+)-induced epileptic discharges in brain slices from rat pups (p 5-8) and juvenile animals (p 15-20). In tissue from rat pups, tiagabine slightly reduced epileptiform activity in hippocampal area CA1 but had no effect in the entorhinal cortex. In juvenile rats, epileptiform discharges were unaffected in CA1 but suppressed by 60% in the entorhinal cortex. While tiagabine increases its efficacy with age, in-situ hybridisation and PCR analysis show that mRNA coding for the neuronal GABA-transporter GAT-1 is already present at p 5. We therefore conclude that the increasing efficacy of tiagabine during ontogenesis is due to functional maturation of GABAergic synapses rather than to up-regulation of GAT-1 expression.

GAD and GABA transporter (GAT-1) mRNA expression in the developing rat hippocampus.

Synaptic inhibition in the mammalian central nervous system is mostly mediated by GABA (gamma-aminobutyric acid). Inhibitory interneurons can be identified by staining for glutamate decarboxylase (GAD), the key enzyme which produces the transmitter. After release, GABA is removed from the extracellular space by specific transporters which are localized at the presynaptic endings of interneurons, in adjacent glial processes and, possibly, also in the postsynaptic target cell membranes. The GABAergic system undergoes profound functional and structural changes during the first 2 weeks of postnatal development, including migration of interneurons and changes in the level of expression and subcellular distribution of GABA transporters. We therefore analyzed the distribution of mRNA coding for GAD and GAT-1 (the main neuronal GABA transporter) in the developing rat hippocampus. Our data show that both transcripts are present in putative interneurons from the first postnatal day and exhibit a largely similar distribution throughout postnatal ontogenesis, with some specific differences in certain hippocampal subfields. Quantification of stained somata confirmed the postnatal redistribution of putative interneurons in the area dentata from dendritic layers towards the hilus. We also found a general staining of principal cell layers for both probes, which differs with postnatal age and between GAD and GAT-1 mRNA. Together, our data reveal a profound reorganization of the GABAergic system in the rat hippocampus during the first weeks of postnatal development.

Presence of gamma-aminobutyric acid transporter mRNA in interneurons and principal cells of rat hippocampus.

After release, neurotransmitters are removed from the extracellular space by high-affinity uptake. Specific sodium-dependent transporters serve this function for the inhibitory transmitter gamma-aminobutyric acid (GABA). However, it is largely unknown to which proportion GABA is taken up by GABAergic interneurons, glia cells or principal neurons. We analyzed the distribution of mRNA for the main GABA-transporter subtype in the hippocampus, GAT-1, in adult rats. Most interneurons were strongly stained for GAT-1 mRNA, indicating re-uptake by the GABA-releasing cells. Surprisingly, prominent signals for GAT-1 were also found throughout the principal cell layers (granule and pyramidal cells). These data indicate that GABA transporters may be present in non-GABAergic projection cells of the rat hippocampus which contribute to the clearance of GABA from the extracellular space.

Acute effects of gamma-vinyl-GABA on low-magnesium evoked epileptiform activity in vitro.

Vigabatrin (gamma-vinyl-GABA, VGB) is a gamma-aminobutyric acid (GABA) derivative designed to boost synaptic inhibition by inhibiting the degradation of GABA in brain tissue. Indeed, VGB shows potent anti-convulsant activity in animal models of epilepsy and in humans with complex partial seizures. However, details of the mechanism of action of VGB are not well understood and the systemic effects include possible pro-convulsant actions. We therefore analysed the effects of VGB in rat brain slices in the low-Mg(2+) model in vitro. VGB at 100 microM-5 mM showed a concentration- and time-dependent reduction of interictal-like events in the hippocampal CA1 region. Likewise, VGB suppressed epileptiform discharges in the medial entorhinal cortex (mEC), which are known to resist conventional anti-convulsants. In contrast, evoked population spikes in CA1 (which became repetitive after washout Mg(2+)) were not altered by VGB. Our data show that VGB is efficient against epileptiform discharges in temporal structures including pharmacoresistant patterns of activity. The waveform of evoked population spikes in this in vitro model is no indicator for the anti-convulsant properties of drugs.

[A new laser puncture guidance device for CT- and MRT-guided punctures of the trunk]. / Ein neues Laser-Punktionsvisier für CT- und MRT-gesteuerte Punktionen des Körperstamms.

A stereotactic device was developed to facilitate CT- or MR-guided punctures of the body. The correct needle angulation is checked by the reflection of fan-shaped red and green laser beams upon the needle. Due to its principle of function and design the device has considerable advantages: The puncture angle can be controlled in three dimensions. The freedom of movement within the operation area will not be affected. The device does not have to be permanently installed and can be employed in MRI at any field strength. Furthermore, all kinds of puncture instruments can be used.

[Technique of MRT-guided core biopsy in the abdomen using an open low-field scanner: feasibility and initial clinical results]. / Technik der MRT-gesteuerten Stanzbiopsie im Abdomen an einem offenen Niederfeldgerät: Durchführbarkeit und erste klinische Ergebnisse.

PURPOSE: Due to high soft-tissue contrast and multiplanar imaging capabilities MRI is an interesting modality to perform image-guided biopsies. We checked on the feasibility of MR-guided core biopsies of abdominal masses with an open low-field scanner (0.2 Tesla; vertical field axis). METHODS: 9 patients underwent MR-guided biopsies of abdominal target lesions (6 focal liver lesions, two adrenal masses, one pelvic mass). Different MR-compatible core biopsy instruments were used (needle diameters 14G-18G). MR scans during the procedures were obtained applying T1-weighted gradient echo sequences suitable for breath-hold imaging. RESULTS: In each case, needle guidance was reliable, so that the biopsy instrument could be positioned correctly. Multiplanar imaging capabilities enabled even angled approaches to upper abdominal masses to be realized safely. The combination of magnet design and table design offered suitable access to the patient. CONCLUSION: Using an open low-field scanner, MR-guided core biopsies of abdominal masses are practicable.

[A technic of MRT-guided abdominal drainage with an open low-field magnet. Its feasibility and the initial results]. / Technik der MRT-gesteuerten abdominellen Drainage an einem offenen Niederfeldmagneten. Durchführbarkeit und erste Ergebnisse.

PURPOSE: To test the practicality of MRT-aided drainage using an open low-field magnet and to report on the early clinical results. METHODS: So far seven patients have been treated (four subphrenic abscesses, two psoas abscesses and one pancreatic pseudocyst). The planning of the approach and catheter insertion were carried out under MRT control (Magnetom Open, 0.2 T). Subsequent treatment was controlled by CT and fluoroscopy. Initial puncture was carried out with a non-magnetic 18 gauge Chiba needle. The drainage catheter was introduced by Seldinger's technique in six cases and with a trocar in one patient. RESULTS: In all seven patients drainage could be started successfully. The design of the magnet and coils permitted adequate accessibility of the patient. There were no problems in visualising the puncture needle. Controlling the position of the catheter by MRT was, however, difficult. CONCLUSION: The first two steps in abscess drainage (planning the approach and inserting the catheter) can be carried out under MRT control. For further catheter control and observing the course of the disease we presently prefer CT or fluoroscopy.

[Early results with a monorail-stent-balloon device for endovascular treatment of renal artery stenosis]. / Erste Erfahrungen mit einem Monorail-Stent-Ballon-System zur endovaskulären Behandlung von Nierenarterienstenosen.

OBJECTIVE: To evaluate the technical feasibility of a new monorail-stent-balloon device for treatment of renal artery stenosis (RAS). PATIENTS AND METHODS: During a study period of 18 months, 38 patients with proven RAS in 41 cases (hypertension n = 36, renal insufficiency n = 13) and indication for stenting (calicified ostial lesions n = 35, insufficient PTA n = 4, dissection n = 2) were enrolled into this prospective evaluation. Pre-mounted stents (Rx-Herculink(TM) 5 mm = 13, 6 mm = 34, 7 mm = 1) were implanted a transfemoral (n = 35) or transbrachial approach (n = 6). Mean grade and lengths of stenosis measured were 88 % plus minus 10 and 9 mm plus minus 5. RESULTS: Renal stent implantation was technically successful in all cases (100 %). In 7 cases a second stent had to be implanted to cover the entire lesion. The transstenotic pressure drop decreased from 88 mmHg plus minus 10 before to 1 mmHg plus minus 1.8 after the procedure. Remaining stenosis measured 0.7 % plus minus 4.2. Serum creatine levels decreased from 1.9 mm/dl to 1.5 mg/dl (n. s.), blood pressure decreased from 178/94 mmHg to 148/79 mmHg (p < 0.0001) after the intervention. Primary and secondary patency rates at 6 months were 72 % (Standard Error 9.8 %) and 77 (% (Standard Error 9.2 %), respectively. CONCLUSION: With the used monorail-stend-balloon device a technically easy, secure and exact renal stent placement is guaranteed, patency rates are similar to those described in the current literature.

[Esophageal scintigraphy of Zenker's diverticula before and after diverticulotomy]. / Osophagusszintigraphie von Zenkerschen Divertikeln vor und nach Divertikulotomie.

AIM: The filling and evacuation of Zenker's diverticula were scintigraphically examined before and after operation to quantify their functional relevance. These results were correlated with the symptoms of the patients and the findings of the barium swallow x-ray examination using cineradiography. METHODS: Sequential and static esophageal scintigraphies were performed in 17 patients with Zenker's diverticulum before and after laser surgical diverticulotomy. We used a gamma camera system in 45 degrees LAO-position after application of 15 ml of tea which was marked with 99mTc-DTPA. Filling and evacuation of the diverticulum were expressed in proportion to the administered activity. Relative volumes of the diverticula were obtained from cineradiography by using the height of the neighbouring cervical vertebra, and the clinical symptoms were divided into 4 groups. RESULTS: Zenker's diverticula could be verified visually and quantitatively by scintigraphy. The precise temporal course of the reduction of activity in the diverticulum was exactly determined. The scintigraphic retentions correlated with the x-ray volumes with a coefficient ranging from 0.55 to 0.85. Clinical symptoms also were not very closely related to scintigraphic and x-ray findings, respectively. CONCLUSION: The esophageal scintigraphy allows quantification of the filling and evacuation of Zenker's diverticula, thus it is suitable for objectivization of the functional relevance of the diverticula. That's why the esophageal scintigraphy should be taken to the diagnosis of diverticula in addition to the clinic and the x-ray examinations. The method is especially useful to evaluate the results after diverticulotomy.

[Anti-inflammatory and analgesic actions of of long-chain phenyl substituted alpha-aminoketones]. / Antiphlogistische und analgetische Wirkungen von längerkettigen phenylsubstituierten alpha-Aminoketonen.

The investigated phenyl substituted alpha-amino ketones have anti-inflammatory and analgesic activities as could be shown in animal models (rats and mice). The effectiveness depends on the length of the alkyl chain. After i.p. application the most active amino ketones are ten times more effective than acetyl salicylic acid, but the activity did not reach that of indomethacin. The effective analgesic dose is ten times lower than that for anti-inflammatory action. Including the results of the toxicity the analgesic efficiency of the amino ketones could be lead to substances with high analgesic activity. After oral administration only in high doses anti-inflammatory and analgesic effectivities were found. The structural analog keto group instead of the ester or amid group leads not to the expected increase in p.o. effectivity.

Morg1(+/-) heterozygous mice are protected from experimentally induced focal cerebral ischemia.

Focal cerebral ischemia (stroke) and reperfusion injury leads to acute and chronic brain damage. The increase of the hypoxia-inducible transcription factor alpha (HIF-α), an important transcription factor for several genes, may attenuate ischemic brain injury. We recently identified a new WD-repeat protein designated Morg1 (MAPK organizer 1) that interacts with prolyl hydroxylase 3 (PHD3), an important enzyme involved in the regulation of HIF-1α and HIF-2α expression. While homozygous Morg1(-/-) mice are embryonically lethal, heterozygous Morg1(+/-) mice have a normal phenotype. Brain vasculature as well as systolic blood pressure in Morg1(+/-) mice were indistinguishable from wild-type (WT) animals. We show here that Morg1(+/-) mice were partially protected from cerebral ischemia/reperfusion injury in comparison to WT (Morg1(+/+)) animals using the middle cerebral artery occlusion model (MCAO). Morg1(+/-) mice compared with WT animals revealed a significantly reduced infarct volume as detected by Nissl and Map 2 staining despite a similar restriction of blood flow in both mice genotypes as measured by laser Doppler flowmetry. Immunohistochemistry revealed specific Morg1 expression in reactive astrocytes in the ipsilateral (ischemic) hemisphere in Morg1(+/-) and WT mice, especially in the penumbral regions. In the contralateral hemisphere, Morg1 was not detectable. Furthermore, Morg1 mRNA expression was significantly enhanced in the ischemic brain of WT, but not in ischemic brain tissue obtained from Morg1(+/-) animals. However, HIF-1α was expressed with the same intensity in Morg1(+/-) and WT mice with no difference between the ipsilateral and contralateral hemispheres. No positive staining for HIF-2α was found in ischemic (ipsilateral) and non-ischemic (contralateral) brain regions in Morg1(+/+) and Morg1(+/-) mice. Almost no PHD3 staining was found in the contralateral hemispheres of either WT or heterozygous Morg1(+/-) mice. Transcript expression for the HIF1α-dependent genes erythropoietin (Epo) and vascular endothelial growth factor 164 (VEGF 164) were significantly reduced in the ischemic brain from Morg1(+/-) mice. Positive staining for PHD3 in the ipsilateral hemisphere of WT mice was suggested to occur in astrocytes. A compensatory increase in Morg1 expression in astrocytes in the penumbra may negatively influence infarct volume. It appears that these effects are independent of the PHD3-HIF1α axis.

Inter-age variability of bona fide unvaried transcripts Normalization of quantitative PCR data in ischemic stroke.

BACKGROUND: Aging is a major risk factor for a variety of neurobiological diseases leading to variations of transcriptional expression in affected tissues. Reverse transcription of RNA followed by quantitative PCR is a powerful technique for detection and quantification of specific transcripts differentially expressed. An essential prerequisite for accurate interpretation of quantitative PCR data obtained from expression studies is an appropriate normalization process. Therefore we validated the expression of the most frequently used reference genes consisting of Gapdh and Actb as well as Hmbs, Hprt1 and Gusb in an animal model of mice in respect to two major influence factors, aging and ischemia. In the experimental settings we intended to reflect variations in both, the local and systemic immune response. RESULTS: The consistency in gene expression of the tested transcripts was quantified based on standard deviation, correlation analysis and two algorithms available as Visual Basic Applications (VBA) termed GeNorm and Normfinder. Overall, the results of the study proofed the suitability of Actb in combination with Gapdh and with tissue-specific limitations Hmbs in brain and Gusb in white blood cells as the most stable transcripts for accurate normalization. We clearly demonstrated that both, the aging process per se and aging in combination with ischemia are confounding factors with respect to the expression stability of Hprt1. CONCLUSIONS: The present study emphasizes the urgent need to validate the expression stability also from bona fide unvaried transcripts under specific conditions of investigation to ensure adequate normalization of qPCR data. Based on the expression stability, the use of Gapdh and Actb as highly abundant transcripts for normalization of qPCR data under conditions of aging and ischemia in a mouse model was evaluated. However, for low abundant genes the use of Hmbs in brain and Gusb in white blood cells is recommended.