Anesthesia experience in an adult Silver-Russell syndrome: a case report

BACKGROUND

There are no reports of anesthesia use in adult patients with Silver-Russell syndrome (SRS). Here, we report our experience with anesthesia in an adult patient with SRS complicated by chronic respiratory failure.

CASE PRESENTATION

A 33-year-old woman was clinically diagnosed with SRS. She had severe chronic respiratory failure, complicated by superior mesenteric artery syndrome. Percutaneous gastrostomy was scheduled for nutritional management under epidural anesthesia; however, soon after esophagogastroduodenoscopy was started, she lost consciousness and spontaneous respiration. The patient was urgently intubated and converted to general anesthesia. The end-tidal carbon dioxide tension was > 90 mmHg at intubation.

CONCLUSIONS

Adult SRS patients with chronic respiratory failure have a risk of CO2 narcosis. SRS also requires preparation for difficult airway management during the perioperative period.

Influence of the descending pain-inhibiting serotonergic pathway on the antihyperalgesic effect of gabapentin in neuropathic pain model rats

Gabapentinoids are used worldwide as first-line agents for the treatment of neuropathic pain. Accumulating evidence indicates that one of the antihyperalgesic mechanisms of gabapentinoids is through activation of the noradrenergic pathway of the descending pain inhibition system. However, the involvement of the serotonin pathway is unclear. We investigated the effects of gabapentin (GBP) on the serotonergic pathway of the descending inhibitory system using the spinal nerve ligation (SNL) rat model. As in previous reports, administration of GBP to SNL rats improved paw withdrawal thresholds (PWT). Intrathecally administered serotonin receptor antagonists abolished GBP's amelioration in PWT. GBP did not ameliorate PWT in noradrenaline-depleted SNL rats by DSP-4. However, GBP ameliorated PWT in serotonin-depleted SNL rats by para-chlorophenylalanine, which was not inhibited by intrathecal administration of a serotonin receptor antagonist. Immunohistochemical analysis of serotonin in the spinal dorsal horn revealed a slight, albeit statistically insignificant, increase in 5-HT levels in SNL rats compared to naive rats. However, no apparent changes were observed before or after GBP administration in naive and SNL rats. In conclusion, the involvement of the serotonergic pathway in the antihyperalgesic effects of GBP on the spinal cord is secondary, although it cooperates with the noradrenergic system to produce analgesia.

The Japanese Epidemiologic Study for Perioperative Anaphylaxis, a prospective nationwide study: clinical signs, severity, and therapeutic agents

BACKGROUND

Diagnosis of perioperative anaphylaxis is difficult because of its non-specific and variable signs and symptoms. Therapeutic agents used to treat anaphylaxis and anaesthesiologist responses also vary depending on the case, which might affect outcomes; however, only a few studies have focused on these factors.

METHODS

This prospective study of perioperative anaphylaxis, a part of the Japanese Epidemiologic Study for Perioperative Anaphylaxis, investigated the clinical signs, its severity, therapeutic drugs, epinephrine administration, and anaesthesiologist responses in cases of perioperative anaphylaxis to assess trends and variability. Shock index was used to assess severity of cardiovascular collapse.

RESULTS

In 43 patients analysed in this study, cardiovascular signs (88.4%) were the most frequent, followed by skin (81.4%) and respiratory signs (60.5%). The presence of signs increased during the clinical course. The median time from the first signs to diagnosis of anaphylaxis was 10 (5.0-17.8) min. The rates of epinephrine use were 30.2% (unused), 48.8% (i.v.), and 20.9% (i.m.). The median time from diagnosis of anaphylaxis to epinephrine administration was 7 (inter-quartile range: 1.5-8.0) min. Antihistamines and corticosteroids were each used in 69.8% of cases. The worst shock index was higher in patients who received i.v. epinephrine (2.77 [0.90] mean [standard deviation]) than in both no epinephrine use cases (1.35 [0.41]) and i.m. epinephrine cases (1.89 [0.77] (P<0.001]).

CONCLUSIONS

The clinical signs and treatments of perioperative anaphylaxis are variable, and the choice regarding epinephrine administration is based on symptom severity.

CLINICAL TRIAL REGISTRATION

UMIN000035350.

Cerebrospinal fluid-contacting neuron tracing reveals structural and functional connectivity for locomotion in the mouse spinal cord

Cerebrospinal fluid-contacting neurons (CSF-cNs) are enigmatic mechano- or chemosensory cells lying along the central canal of the spinal cord. Recent studies in zebrafish larvae and lampreys have shown that CSF-cNs control postures and movements via spinal connections. However, the structures, connectivity, and functions in mammals remain largely unknown. Here we developed a method to genetically target mouse CSF-cNs that highlighted structural connections and functions. We first found that intracerebroventricular injection of adeno-associated virus with a neuron-specific promoter and Pkd2l1-Cre mice specifically labeled CSF-cNs. Single-cell labeling of 71 CSF-cNs revealed rostral axon extensions of over 1800 μm in unmyelinated bundles in the ventral funiculus and terminated on CSF-cNs to form a recurrent circuitry, which was further determined by serial electron microscopy and electrophysiology. CSF-cNs were also found to connect with axial motor neurons and premotor interneurons around the central canal and within the axon bundles. Chemogenetic CSF-cNs inactivation reduced speed and step frequency during treadmill locomotion. Our data revealed the basic structures and connections of mouse CSF-cNs to control spinal motor circuits for proper locomotion. The versatile methods developed in this study will contribute to further understanding of CSF-cN functions in mammals.

Neuronal Nitric Oxide Synthase Suppression Confers the Prolonged Analgesic Effect of Sciatic Nerve Block with Perineural Dexamethasone in Postoperative Pain Model Mice

Dexamethasone supplementation to local anesthetics prolongs its action, yet the underlying mechanism is unclear. Previous studies have reported that increased p-p38 mitogen-activated protein kinase (MAPK) in the dorsal root ganglia (DRG) is associated with pain-associated behavior and that nitric oxide (NO), which is known to be a pronociceptive substance, directly inhibits sciatic nerve conduction. Here, we investigated the temporal changes in the hyperalgesic effect and p-p38 MAPK and NO synthase (NOS) expression levels in the DRG when dexamethasone was added to ropivacaine used for a sciatic nerve block (SNB) in postoperative pain model mice. Dexamethasone supplementation to ropivacaine significantly prolonged the analgesic effect of SNB via glucocorticoid receptor activation. Histological examination revealed that ropivacaine suppressed p-p38 MAPK expression in the DRG regardless of dexamethasone supplementation, suggesting that p-p38 MAPK was not involved in the prolonging effect of dexamethasone on nerve block. Contrastingly, plantar incision markedly increased the expression of neuronal NOS (nNOS) in DRG, and dexamethasone supplementation to ropivacaine significantly suppressed nNOS expression. Supplementation of L-NAME, an inhibitor of NOS, to ropivacaine markedly prolonged the effect of SNB, similar to dexamethasone. These results suggest that dexamethasone supplementation to local anesthetics prolongs the analgesic effect by inhibiting nNOS activity.

Subanesthetic Dose of Propofol Activates the Reward System in Rats

BACKGROUND

Propofol has addictive properties, even with a single administration, and facilitates dopamine secretion in the nucleus accumbens (NAc). Activation of the dopaminergic circuits of the midbrain reward system, including the ventral tegmental area (VTA) and NAc, plays a crucial role in addiction. However, the effects of propofol on synaptic transmission and biochemical changes in the VTA-NAc circuit remain unclear.

METHODS

We investigated the effects of subanesthetic doses of propofol on rat VTA neurons and excitatory synaptic transmission in the NAc using slice patch-clamp experiments. Using immunohistochemistry and western blot analyses, we evaluated the effects of intraperitoneal propofol administration on the expression of addiction-associated transcription factor ΔFosB (truncated form of the FBJ murine osteosarcoma viral oncogene homolog B protein) in the NAcs in 5-week-old rats.

RESULTS

In the current-clamp mode, a subanesthetic dose (0.5-5 µmol/L) of propofol increased the action potential frequency in about half the VTA neurons (excited neurons: control: 9.4 ± 3.0 Hz, propofol 0.5 µmol/L: 21.5 ± 6.0 Hz, propofol 5 µmol/L: 14.6 ± 5.3 Hz, wash: 2.0 ± 0.7 Hz, n = 14/27 cells; unchanged/suppressed neurons: control: 1.68 ± 0.94 Hz, propofol 0.5 µmol/L: 1.0 ± 0.67 Hz, propofol 5 µmol/L: 0.89 ± 0.87 Hz, wash: 0.16 ± 0.11 Hz, n = 13/27 cells). In the voltage-clamp mode, about half the VTA principal neurons showed inward currents with 5 µmol/L of propofol (inward current neurons: control: -20.5 ± 10.0 pA, propofol 0.5 µmol/L: -62.6 ± 14.4 pA, propofol 5 µmol/L: -85.2 ± 18.3 pA, propofol 50 µmol/L: -17.1 ± 39.2 pA, washout: +30.5 ± 33.9 pA, n = 6/11 cells; outward current neurons: control: -33.9 ± 14.6 pA, propofol 0.5 µmol/L: -29.5 ± 16.0 pA, propofol 5 µmol/L: -0.5 ± 20.9 pA, propofol 50 µmol/L: +38.9 ± 18.5 pA, washout: +40.8 ± 32.1 pA, n = 5/11 cells). Moreover, 0.5 µmol/L propofol increased the amplitudes of evoked excitatory synaptic currents in the NAc, whereas >5 µmol/L propofol decreased them (control: 100.0 ± 2.0%, propofol 0.5 µmol/L: 118.4 ± 4.3%, propofol 5 µmol/L: 98.3 ± 3.3%, wash [within 10 min]: 70.7 ± 3.3%, wash [30 minutes later]: 89.9 ± 2.5%, n = 13 cells, P < .001, Dunnett's test comparing control and propofol 0.5 µmol/L). Intraperitoneally administered subanesthetic dose of propofol increased ΔFosB expression in the NAc, but not in VTA, 2 and 24 hours after administration, compared with the Intralipid control group (propofol 2 hours: 0.94 ± 0.15, 24 hours: 0.68 ± 0.07; Intralipid 2 hours: 0.40 ± 0.03, 24 hours: 0.37 ± 0.06, P = .0002 for drug in the 2-way analysis of variance).

CONCLUSIONS

Even a single administration of a subanesthetic dose of propofol may cause rewarding change in the central nervous system. Thus, there is a potential propofol rewarding effect among patients receiving anesthesia or sedation with propofol, as well as among health care providers exposed to propofol.

Sex differences in pain-induced modulation of corticotropin-releasing hormone neurons in the dorsolateral part of the stria terminalis in mice

We earlier reported female-biased, sex-specific involvement of the dorsolateral bed nucleus of the stria terminalis (dl BST) in the formalin-induced pain response in rats. The present study investigated pain effects on mice behaviors. Because the dl BST is densely populated with corticotropin-releasing hormone (CRH) neurons, we examined sex differences in these parameters for the dl BST CRH neurons in male and female mice of a mouse line for which the CRH gene promoter (corticotropin-releasing factor [CRF]-Venus ΔNeo) controls the expression of the modified yellow fluorescent protein (Venus). Approximately 92% of Venus-positive cells in the dl BST were also CRH mRNA-positive, irrespective of sex. Therefore, the cells identified using Venus fluorescence were regarded as CRH neurons. A female-biased sex difference was observed in pain-induced behaviors during the interphase (5-15 min after formalin injection) but not during the later phase (phase 2, 15-60 min) in wild-type mice. In CRF-Venus ΔNeo mice, a female-biased difference was observed in either the earlier phase (phase 1, 0-5 min) or the interphase, but not in phase 2. Patch-clamp recordings taken using an acute BST slice obtained from a CRF-Venus ΔNeo mouse after formalin injection showed miniature excitatory postsynaptic currents (mEPSCs) and miniature inhibitory postsynaptic currents (mIPSCs). Remarkably, the mEPSCs frequency was higher in the Venus-expressing cells of formalin-injected female mice than in vehicle-treated female mice. Male mice showed no increase in mEPSC frequency by formalin injection. Formalin injection had no effect on mEPSC or mIPSC amplitudes in either sex. Pain-induced changes in mEPSC frequency in putative CRH neurons were phase-dependent. Results show that excitatory synaptic inputs to BST CRH neurons are temporally enhanced along with behavioral sex differences in pain response, suggesting that pain signals alter the BST CRH neurons excitability in a sex-dependent manner.

Effects of the Kampo medicine Yokukansan for perioperative anxiety and postoperative pain in women undergoing breast surgery: A randomized, controlled trial

Yokukansan (YKS) is a traditional Japanese herbal (Kampo) medicine prescribed for anxiety. In this randomized controlled trial, we compared the subjective assessment of anxiety using questionnaires and its objective assessment using salivary alpha-amylase concentrations in YKS and control (CNT) groups of women undergoing breast surgery. The trial was registered at the University Hospital Medical Information Network Clinical Trials Registry (registration number: UMIN000028998), and the investigators were blinded to drug administration. One hundred patients who underwent breast cancer surgery were allocated to either the YKS or the CNT group. Finally, 35 and 42 patients in the YKS and CNT groups were analyzed, respectively. The YKS group received two 2.5 g doses of the medication before sleeping on the night before surgery and 2 h before inducing anesthesia, while the CNT group did not receive medication preoperatively. Patients answered two questionnaires, the Hospital Anxiety and Depression Scale and the State-Trait Anxiety Inventory, pre-and postoperatively as subjective anxiety assessments. As an objective anxiety indicator, salivary alpha-amylase levels were measured the day before, directly before, and the day after surgery (T3). In the YKS group, salivary alpha-amylase scores directly before operation were significantly lower than those on the day before surgery and at one day postoperatively (F [2,150] = 3.76, p = 0.03). Moreover, the Hospital Anxiety and Depression Scale-Anxiety and State-Trait Anxiety Inventory-Trait scores were significantly more improved postoperatively in the YKS group than in the CNT group (difference in Hospital Anxiety and Depression Scale-Anxiety: YKS, mean -2.77, 95% confidence interval [-1.48 --4.06], p <0.001, and CNT, -1.43 [-0.25--2.61], p = 0.011; and difference in State-Trait Anxiety Inventory: YKS group, -4.23 [-6.95--1.51], p = 0.0004; and CNT group, 0.12 [-2.36-2.60], p = 0.92). No side effects were associated with YKS. YKS may reduce perioperative anxiety in patients undergoing surface surgery.

A Bolus Dose of Ketamine Reduces the Amplitude of the Transcranial Electrical Motor-evoked Potential: A Randomized, Double-blinded, Placebo-controlled Study

BACKGROUND

A low-dose bolus or infusion of ketamine does not affect transcranial electrical motor-evoked potential (MEP) amplitude, but a dose ≥1 mg/kg may reduce MEP amplitude. We conducted a randomized, double-blinded, placebo-controlled study to evaluate the effect of ketamine (1 mg/kg) on transcranial electrical MEP.

METHODS

Twenty female patients (aged 12 to 18 y) with adolescent idiopathic scoliosis scheduled to undergo posterior spinal fusion were randomly allocated to receive ketamine or saline. General anesthesia was induced and maintained with continuous infusions of propofol and remifentanil. MEP was elicited by supramaximal transcranial electrical stimulation. MEP recordings were obtained at baseline and then at 2, 4, 6, 8, and 10 minutes after administration of ketamine (1 mg/kg) or saline (0.1 ml/kg). The primary endpoint was the minimum relative MEP amplitude (peak-to-peak amplitude, % of baseline value) recorded from the left tibialis anterior muscle. The baseline amplitude recorded before test drug administration was defined as 100%.

RESULTS

Medians (interquartile range) minimum MEP amplitudes in the left tibialis anterior muscle in the ketamine and saline groups were 26% (9% to 34%) and 87% (55% to 103%) of the baseline value, respectively (P<0.001). MEP amplitudes in other muscles were significantly reduced by ketamine. The suppressive effect of ketamine lasted for at least 10 minutes in each muscle.

CONCLUSION

A 1-mg/kg bolus dose of ketamine can reduce MEP amplitude. Anesthesiologists should consider the dosage and timing of intravenous ketamine administration during MEP monitoring.

Serotonin Plays a Key Role in the Development of Opioid-Induced Hyperalgesia in Mice

Opioid usage for pain therapy is limited by its undesirable clinical effects, including paradoxical hyperalgesia, also known as opioid-induced hyperalgesia (OIH). However, the mechanisms associated with the development and maintenance of OIH remain unclear. Here, we investigated the effect of serotonin inhibition by the 5-HT3 receptor antagonist, ondansetron (OND), as well as serotonin deprivation via its synthesis inhibitor para-chlorophenylalanine, on mouse OIH models, with particular focus on astrocyte activation. Co-administering of OND and morphine, in combination with serotonin depletion, inhibited mechanical hyperalgesia and astrocyte activation in the spinal dorsal horn of mouse OIH models. Although previous studies have suggested that activation of astrocytes in the spinal dorsal horn is essential for the development and maintenance of OIH, herein, treatment with carbenoxolone (CBX), a gap junction inhibitor that suppresses astrocyte activation, did not ameliorate mechanical hyperalgesia in mouse OIH models. These results indicate that serotonin in the spinal dorsal horn, and activation of the 5-HT3 receptor play essential roles in OIH induced by chronic morphine, while astrocyte activation in the spinal dorsal horn serves as a secondary effect of OIH. Our findings further suggest that serotonergic regulation in the spinal dorsal horn may be a therapeutic target of OIH. PERSPECTIVE: The current study revealed that the descending serotonergic pain-facilitatory system in the spinal dorsal horn is crucial in OIH, and that activation of astrocytes is a secondary phenotype of OIH. Our study offers new therapeutic targets for OIH and may help reduce inappropriate opioid use.

Propofol reduces the amplitude of transcranial electrical motor-evoked potential without affecting spinal motor neurons: a prospective, single-arm, interventional study

PURPOSE

Propofol inhibits the amplitudes of transcranial electrical motor-evoked potentials (TCE-MEP) in a dose-dependent manner. However, the mechanisms of this effect remain unknown. Hence, we investigated the spinal mechanisms of the inhibitory effect of propofol on TCE-MEP amplitudes by evaluating evoked electromyograms (H-reflex and F-wave) under general anesthesia.

METHODS

We conducted a prospective, single-arm, interventional study including 15 patients scheduled for spine surgery under general anesthesia. Evoked electromyograms of the soleus muscle and TCE-MEPs were measured at three propofol concentrations using target-controlled infusion (TCI: 2.0, 3.0, and 4.0 µg/mL). The primary outcome measure was the left H-reflex amplitude during TCI of 4.0- compared to 2.0-µg/mL propofol administration.

RESULTS

The median [interquartile range] amplitudes of the left H-reflex were 4.71 [3.42-6.60] and 5.6 [4.17-7.46] in the 4.0- and 2.0-μg/mL TCI groups (p = 0.4, Friedman test), respectively. There were no significant differences in the amplitudes of the right H-reflex and the bilateral F-wave among these groups. However, the TCE-MEP amplitudes significantly decreased with increased propofol concentrations (p < 0.001, Friedman test).

CONCLUSION

Propofol did not affect the amplitudes of the H-reflex and the F-wave, whereas TCE-MEP amplitudes were reduced at higher propofol concentrations. These results suggested that propofol can suppress the TCE-MEP amplitude by inhibiting the supraspinal motor pathways more strongly than the excitability of the motor neurons in the spinal cord.

Epidural Administration of Ropivacaine Reduces the Amplitude of Transcranial Electrical Motor-Evoked Potentials: A Double-Blinded, Randomized, Controlled Trial

BACKGROUND

An epidurally administered local anesthetic acts primarily on the epidural nerve roots and can act directly on the spinal cord through the dural sleeve. We hypothesized that epidurally administered ropivacaine would reduce the amplitude of transcranial electrical motor-evoked potentials by blocking nerve conduction in the spinal cord. Therefore, we conducted a double-blind, randomized, controlled trial.

METHODS

Thirty adult patients who underwent lung surgery were randomly allocated to 1 of 3 groups, based on the ropivacaine concentration: the 0.2% group, the 0.375% group, and the 0.75% group. The attending anesthesiologists, neurophysiologists, and patients were blinded to the allocation. The epidural catheter was inserted at the T5-6 or T6-7 interspace by a paramedian approach, using the loss of resistance technique with normal saline. General anesthesia was induced and maintained using propofol and remifentanil. Transcranial electrical motor-evoked potentials were elicited by a train of 5 pulses with an interstimulus interval of 2 milliseconds by using a constant-voltage stimulator and were recorded from the tibialis anterior muscle. Somatosensory-evoked potentials (SSEPs) were evoked by electrical tibial nerve stimulation at the popliteal fossa. After measuring the baseline values of these evoked potentials, 10 mL of epidural ropivacaine was administered at the 0.2%, 0.375%, or 0.75% concentration. The baseline amplitudes and latencies recorded before administering ropivacaine were defined as 100%. Our primary end point was the relative amplitude of the motor-evoked potentials at 60 minutes after the epidural administration of ropivacaine. We analyzed the amplitudes and latencies of these evoked potentials by using the Kruskal-Wallis test and used the Dunn multiple comparison test as the post hoc test for statistical analysis.

RESULTS

The data are expressed as the median (interquartile range). Sixty minutes after epidurally administering ropivacaine, the motor-evoked potential amplitude was lower in the 0.75% group (7% [3%-18%], between-group difference P < .001) and in the 0.375% group (52% [43%-59%]) compared to that in the 0.2% group (96% [89%-105%]). The latency of SSEP was longer in the 0.75% group compared to that in the 0.2% group, but the amplitude was unaffected.

CONCLUSIONS

Epidurally administered high-dose ropivacaine lowered the amplitude of motor-evoked potentials and prolonged the onset latencies of motor-evoked potentials and SSEPs compared to those in the low-dose group. High-dose ropivacaine can act on the motor pathway through the dura mater.

SUZYTM forceps facilitate nasogastric tube insertion under McGRATHTM MAC videolaryngoscopic guidance: A randomized, controlled trial

BACKGROUND

Nasogastric tubes can be easily inserted in patients under general anesthesia. However, for difficult cases, insertion techniques that can be used in routine clinical practice are limited. SUZY forceps are designed for the removal of pharyngolaryngeal foreign bodies under guidance of a McGrath videolaryngoscope. We hypothesized that using SUZY forceps under McGrath videolaryngoscopic guidance may facilitate nasogastric tube insertion and tested this in a randomized controlled trial.

METHODS

Adult patients who underwent gastrointestinal or hepato-pancreato-biliary surgery were randomly allocated to 2 groups; the SUZY group and the Magill group. Patients, nurses, and all clinical staff except for the attending anesthesiologist were blinded to group assignment throughout the study. After anesthesia induction, insertion of the nasogastric tube was performed by skilled anesthesiologists with either SUZY or Magill forceps according to group allocation under McGrath videolaryngoscopic guidance. The primary endpoint was insertion time which was defined as the time required to advance the nasogastric tube by 55 cm from the nostril. Secondary endpoints were the success rates of the nasogastric tube insertion, which were defined as a 55-cm advancement from the nostril at the 1st, 2nd, and 3rd attempt, proper insertion rate, the severity of pharyngolaryngeal complications, and hemodynamic parameters during nasogastric tube insertion.

RESULTS

Sixty patients were randomized and none of these patients were excluded from the final analysis. The median [interquartile range] insertion time was 25 [18-33] seconds in the SUZY group, and 33 [21-54] seconds in the Magill group (P = .02). Success rates were not different between the groups (97% and 80% in the SUZY and Magill group at 1st attempt, respectively, P = .10). Both, the severity score of the mucosal injury and the severity of sore throat were higher in the Magill than in the SUZY group, whereas the degree of hoarseness did not differ between the 2 groups. Hemodynamic parameters were not significantly different between the groups.

CONCLUSION

Using SUZY forceps under McGrath videolaryngoscopic guidance reduced the time required to insert a nasogastric tube and the severity of pharyngolaryngeal complications, when compared to using Magill forceps.

Learning Promotes Subfield-Specific Synaptic Diversity in Hippocampal CA1 Neurons

The hippocampus is functionally heterogeneous between the dorsal and ventral subfields with left–right asymmetry. To determine the possible location of contextual memory, we performed an inhibitory avoidance task to analyze synaptic plasticity using slice patch-clamp technique. The training bilaterally increased the AMPA/NMDA ratio at dorsal CA3–CA1 synapses, whereas the training did not affect the ratio at ventral CA3–CA1 synapses regardless of the hemisphere. Moreover, sequential recording of miniature excitatory postsynaptic currents and miniature inhibitory postsynaptic currents from the same CA1 neuron clearly showed learning-induced synaptic plasticity. In dorsal CA1 neurons, the training dramatically strengthened both excitatory and inhibitory postsynaptic responses in both hemispheres, whereas the training did not promote the plasticity in either hemisphere in ventral CA1 neurons. Nonstationary fluctuation analysis further revealed that the training bilaterally increased the number of AMPA or GABA_A receptor channels at dorsal CA1 synapses, but not at ventral CA1 synapses, suggesting functional heterogeneity of learning-induced receptor mobility. Finally, the performance clearly impaired by the bilateral microinjection of plasticity blockers in dorsal, but not ventral CA1 subfields, suggesting a crucial role for contextual learning. The quantification of synaptic diversity in specified CA1 subfields may help us to diagnose and evaluate cognitive disorders at the information level.

Acute spatial spread of NO-mediated potentiation during hindpaw ischaemia in mice

Key points

Neuropathic pain spreads spatially beyond the injured sites, and the mechanism underlying the spread has been attributed to inflammation occurring in the spinal cord.

However, the spatial spread of spinal/cortical potentiation induced by conduction block of the peripheral nerves can be observed prior to inflammation.

In the present study, we found that spreading potentiation and hypersensitivity acutely induced by unilateral hindpaw ischaemia are nitric oxide (NO)‐dependent and that NO is produced by ischaemia and quickly diffuses within the spinal cord.

We also found that NO production induced by ischaemia is not observed in the presence of an antagonist for group II metabotropic glutamate receptors (mGluRs) and that neuronal NO synthase‐positive dorsal horn neurons express group II mGluRs.

These results suggest strongly that NO‐mediated spreading potentiation in the spinal cord is one of the trigger mechanisms for neuropathic pain.

Abstract

Cortical/spinal responses to hindpaw stimulation are bilaterally potentiated by unilateral hindpaw ischaemia in mice. We tested the hypothesis that hindpaw ischaemia produces nitric oxide (NO), which diffuses in the spinal cord to induce spatially spreading potentiation. Using flavoprotein fluorescence imaging, we confirmed that the spreading potentiation in hindpaw responses was induced during ischaemia in the non‐stimulated hindpaw. This spreading potentiation was blocked by spinal application of l‐NAME, an inhibitor of NO synthase (NOS). Furthermore, no spreading potentiation was observed in neural NOS (nNOS) knockout mice. Spinal application of an NO donor was enough to induce cortical potentiation and mechanical hypersensitivity. The spatial distribution of NO during unilateral hindpaw ischaemia was visualized using 4‐amino‐5‐methylamino‐2′,7′‐difluorofluorescein (DAF‐FM). An increase in fluorescence derived from the complex of DAF‐FM with NO was observed on the ischaemic side of the spinal cord. A similar but smaller increase was also observed on the contralateral side. Somatosensory potentiation after hindpaw ischaemia is known to be inhibited by spinal application of LY354740, an agonist of group II metabotropic glutamate receptors (mGluRs). We confirmed that the spinal DAF‐FM fluorescence increases during hindpaw ischaemia were not observed in the presence of LY354740. We also confirmed that approximately half of the nNOS‐positive neurons in the superficial laminae of the dorsal horn expressed mGluR2 mRNA. These results suggest that disinhibition of mGluR2 produces NO which in turn induces a spreading potentiation in a wide area of the spinal cord. Such spreading, along with the consequent non‐specific potentiation in the spinal cord, may trigger neuropathic pain.

Neuropathic pain spreads spatially beyond the injured sites, and the mechanism underlying the spread has been attributed to inflammation occurring in the spinal cord.

However, the spatial spread of spinal/cortical potentiation induced by conduction block of the peripheral nerves can be observed prior to inflammation.

In the present study, we found that spreading potentiation and hypersensitivity acutely induced by unilateral hindpaw ischaemia are nitric oxide (NO)‐dependent and that NO is produced by ischaemia and quickly diffuses within the spinal cord.

We also found that NO production induced by ischaemia is not observed in the presence of an antagonist for group II metabotropic glutamate receptors (mGluRs) and that neuronal NO synthase‐positive dorsal horn neurons express group II mGluRs.

These results suggest strongly that NO‐mediated spreading potentiation in the spinal cord is one of the trigger mechanisms for neuropathic pain.

Neurosteroid dehydroepiandrosterone sulphate enhances pain transmission in rat spinal cord dorsal horn

BACKGROUND

The neurosteroid dehydroepiandrosterone sulphate (DHEAS) activates the sigma-1 receptor, inhibits gamma-aminobutyric acid A (GABA_A) and glycine receptors, and induces hyperalgesic effects. Although its effects have been studied in various tissues of the nervous system, its synaptic mechanisms in nociceptive pathways remain to be elucidated.

METHODS

The threshold of mechanical hypersensitivity and spontaneous pain behaviour was assessed using the von Frey test in adult male Wistar rats after intrathecal administration of DHEAS. We also investigated the effects of DHEAS on synaptic transmission in the spinal dorsal horn using slice patch-clamp electrophysiology.

RESULTS

Intrathecally administered DHEAS elicited dose-dependent mechanical hyperalgesia and spontaneous pain behaviours (withdrawal threshold: saline; 51.0 [20.1] g, 3 μg DHEAS; 14.0 [7.8] g, P<0.01, 10 μg DHEAS; 6.9 [5.2] g, 15 min after administration, P<0.001). DHEAS at 100 μM increased the frequency of miniature postsynaptic currents in the rat dorsal spinal horn; this increase was extracellular Ca²⁺-dependent but not sigma-1 and N-methyl-d-aspartate receptor-dependent. DHEAS suppressed the frequency of miniature inhibitory postsynaptic currents in a GABA_A receptor- and sigma-1 receptor-dependent manner.

CONCLUSIONS

These results suggest that DHEAS participates in the pathophysiology of nociceptive synaptic transmission in the spinal cord by potentiation of glutamate release and inhibition of the GABA_A receptor.

Neural block therapy for radiation enteritis: a case report

Background

Radiation enteritis following radiotherapy targeting the abdomen occasionally causes ulcers or ileus, which can be difficult to treat and usually progressive and refractory, significantly degrading the patient’s quality of life.

Case presentation

A 58-year-old woman had undergone surgery for cervical cancer approximately 21 years ago. During treatment, she had also received radiotherapy targeting the pelvis and stomach. She presented with complaints of vomiting and lower abdominal pain and was subsequently diagnosed with multiple gastric ulcers, enterocolitis, and paralytic ileus due to late radiation-induced sequelae. We reasoned that visceral sympathetic block would improve the abdominal symptoms; therefore, we performed a splanchnic nerve block and an inferior mesenteric artery plexus block. As predicted, these block procedures improved the symptoms.

Conclusions

Radiation enteritis is an iatrogenic disease, and there is no established treatment for intractable cases. However, visceral sympathetic nerve block may show efficacy as a potential therapy for radiation enteritis-associated abdominal pain and ileus.

The nature of spin excitations in the one-third magnetization plateau phase of Ba3CoSb2O9

Magnetization plateaus in quantum magnets—where bosonic quasiparticles crystallize into emergent spin superlattices—are spectacular yet simple examples of collective quantum phenomena escaping classical description. While magnetization plateaus have been observed in a number of spin-1/2 antiferromagnets, the description of their magnetic excitations remains an open theoretical and experimental challenge. Here, we investigate the dynamical properties of the triangular-lattice spin-1/2 antiferromagnet Ba₃CoSb₂O₉ in its one-third magnetization plateau phase using a combination of nonlinear spin-wave theory and neutron scattering measurements. The agreement between our theoretical treatment and the experimental data demonstrates that magnons behave semiclassically in the plateau in spite of the purely quantum origin of the underlying magnetic structure. This allows for a quantitative determination of Ba₃CoSb₂O₉ exchange parameters. We discuss the implication of our results to the deviations from semiclassical behavior observed in zero-field spin dynamics of the same material and conclude they must have an intrinsic origin.

Frustrated magnetic materials attract significant interest because their properties can become dominated by quantum fluctuations. Here the authors show that excitations in the plateau phase of a quantum magnet can be understood semiclassically even though the ground state involves strong quantum effects.

Ordering phenomena in a heterostructure of frustrated and unfrustrated triangular-lattice Ising layers

We study critical and magnetic properties of a bilayer Ising system consisting of two triangular planes A and B, with the antiferromagnetic (AF) coupling J_{A} and the ferromagnetic (FM) one J_{B} for the respective layers, which are coupled by the interlayer interaction J_{AB} by using Monte Carlo simulations. When J_{A} and J_{B} are of the same order, the unfrustrated FM plane orders first at a high temperature T_{c1}∼J_{B}. The spontaneous FM order then exerts influence on the other frustrated AF plane as an effective magnetic field, which subsequently induces a ferrimagnetic order in this plane at low temperatures below T_{c2}. When short-range order is developed in the AF plane while the influence of the FM plane is still small, there appears a preemptive Berezinskii-Kosterlitz-Thouless-type pseudocritical crossover regime just above the ferrimagnetic phase transition point, where the short-distance behavior up to a rather large length scale exponentially diverging in ∝J_{A}/T is controlled by a line of Gaussian fixed points at T=0. In the crossover region, a continuous variation in the effective critical exponent 4/9≲η^{eff}≲1/2 is observed. The phase diagram by changing the ratio J_{A}/J_{B} is also investigated.

Free radical scavenger edaravone produces robust neuroprotection in a rat model of spinal cord injury

We used a multimodal approach to evaluate the effects of edaravone in a rat model of spinal cord injury (SCI). SCI was induced by extradural compression of thoracic spinal cord. In experiment 1, 30 min prior to compression, rats received a 3 mg/kg intravenous bolus of edaravone followed by a maintenance infusion of 1 (low-dose), 3 (moderate-dose), or 10 (high-dose) mg/kg/h edaravone. Although both moderate- and high-dose edaravone regimens promoted recovery of spinal motor-evoked potentials (MEPs) at 2 h post-SCI, the effect of the moderate dose was more pronounced. In experiment 2, moderate-dose edaravone was administered 30 min prior to compression, at the start of compression, or 10 min after decompression. Although both preemptive and coincident administration resulted in significantly improved spinal MEPs at 2 h post-SCI, the effect of preemptive administration was more pronounced. A moderate dose of edaravone resulted in significant attenuation of lipid peroxidation, as evidenced by lower concentrations of the free radical malonyldialdehyde in the spinal cord 3 h post-SCI. Malonyldialdehyde levels in the high-dose edaravone group were not reduced. Both moderate- and high-dose edaravone resulted in significant functional improvements, evidenced by better Basso-Beattie-Bresnahan (BBB) scores and better performance on an inclined plane during an 8 week period post-SCI. Both moderate- and high-dose edaravone significantly attenuated neuronal loss in the spinal cord at 8 weeks post-SCI, as evidenced by quantitative immunohistochemical analysis of NeuN-positive cells. In conclusion, early administration of a moderate dose of edaravone minimized the negative consequences of SCI and facilitated functional recovery.

Comparison of a curved forceps with a conventional straight forceps for nasogastric tube insertion under videolaryngoscopic guidance: A randomized, crossover manikin study

BACKGROUND

Nasogastric tube (NGT) insertion is an easy procedure that can be routinely performed under general anesthesia. However, for difficult cases, there are limited insertion techniques available in routine clinical practice, considering the flexibility of NGTs. The SUZY curved forceps are designed for the removal of pharyngolaryngeal foreign bodies under guidance of the McGRATH MAC (McG) videolaryngoscope. Because McG enables clear visualization of the esophageal inlet, we hypothesized that the SUZY forceps can facilitate easier NGT insertion compared with the conventional Magill forceps under McG guidance and designed a randomized, crossover manikin study to test this hypothesis.

MATERIALS AND METHODS

Ten anesthesiologists participated in this study. Each participant was instructed to insert an NGT using either the SUZY or the Magill forceps under McG guidance. Both types of forceps were used by each participant in a computer-generated random order. The primary outcome measure was the number of "strokes" (1 stroke was defined by a specific sequence of participant actions) required to advance the NGT 30 cm from the starting point. Data are expressed as medians (interquartile ranges [ranges]).

RESULTS

The number of strokes required for NGT insertion was fewer in the SUZY group than in the Magill group {7 [7.0-12.5 (5-14)] vs 16.5 [13.5-20.3 (7-22)]; P <.05}. The time required for NGT insertion was also lesser in the SUZY group than in the Magill group {15.4 [13.7-20.0 (7.0-38.3)] seconds vs 30.3 [22.0-42.3 (12.8-47.5) seconds]; P <.05}.

CONCLUSIONS

The SUZY curved forceps facilitated NGT insertion more effectively than the Magill straight forceps under McG guidance. Our results suggest that NGT insertion using the SUZY forceps under McG guidance is a secure and easy procedure.

A functional coupling between CRMP1 and Nav1.7 for retrograde propagation of Semaphorin3A signaling

Semaphorin3A (Sema3A) is a secreted type of axon guidance molecule that regulates axon wiring through complexes of neuropilin-1 (NRP1) with PlexinA protein receptors. Sema3A regulates the dendritic branching through tetrodotoxin (TTX)-sensitive retrograde axonal transport of PlexA proteins and tropomyosin-related kinase A (TrkA) complex. We here demonstrate that Na_v1.7 (encoded by SCN9A), a TTX-sensitive Na⁺ channel, by coupling with collapsin response mediator protein 1 (CRMP1), mediates the Sema3A-induced retrograde transport. In mouse dorsal root ganglion (DRG) neurons, Sema3A increased co-localization of PlexA4 and TrkA in the growth cones and axons. TTX treatment and RNAi knockdown of Na_v1.7 sustained Sema3A-induced colocalized signals of PlexA4 and TrkA in growth cones and suppressed the subsequent localization of PlexA4 and TrkA in distal axons. A similar localization phenotype was observed in crmp1^-/- DRG neurons. Sema3A induced colocalization of CRMP1 and Na_v1.7 in the growth cones. The half maximal voltage was increased in crmp1^-/- neurons when compared to that in wild type. In HEK293 cells, introduction of CRMP1 lowered the threshold of co-expressed exogenous Na_v1.7. These results suggest that Na_v1.7, by coupling with CRMP1, mediates the axonal retrograde signaling of Sema3A.

Lipid emulsion injection-induced reversal of cardiac toxicity and acceleration of emergence from general anesthesia after scalp infiltration of a local anesthetic: a case report

Background

A scalp block or wound infiltration of local anesthetic is thought to effectively control post-craniotomy pain. However, it can result in local anesthetic toxicity (LAST), which is difficult to distinguish from brain damage due to the surgical procedure when emergence from general anesthesia is delayed. Lipid rescue (infusion of a lipid emulsion) is a widely accepted treatment for LAST.

Case presentation

A 64-year-old man underwent surgical resection of a glioma in the brainstem. While still under general anesthesia, and before suturing of the wound, he received a 20-mL scalp infusion of ropivacaine 0.75%. His emergence from anesthesia was delayed, his respiration was suppressed, and premature ventricular contractions occurred; all of which are symptoms of LAST. Injection of a 20% lipid emulsion rapidly alleviated these symptoms. Interestingly, the blood concentration of ropivacaine increased after lipid rescue.

Conclusions

The increase in ropivacaine concentration in the blood after lipid rescue suggests that the intravenously administered lipid emulsion absorbed the ropivacaine from the intoxicated brain and heart tissue. This finding is consistent with the lipid sink theory as a mechanistic explanation of lipid rescue.

Bumetanide, an Inhibitor of NKCC1 (Na-K-2Cl Cotransporter Isoform 1), Enhances Propofol-Induced Loss of Righting Reflex but Not Its Immobilizing Actions in Neonatal Rats

Gamma-aminobutyric acid (GABA) has been shown to induce excitation on immature neurons due to increased expression of Na+-K+-2Cl- co-transporter isoform 1 (NKCC1), and the transition of GABAergic signaling from excitatory to inhibitory occurs before birth in the rat spinal cord and spreads rostrally according to the developmental changes in cation-chloride co-transporter expression. We previously showed that midazolam activates the hippocampal CA3 area and induces less sedation in neonatal rats compared with adolescent rats in an NKCC1-dependent manner. In the present study, we tested the hypothesis that propofol-induced loss of righting reflex (LORR) but not immobilizing actions are modulated by NKCC1-dependent mechanisms and reduced in neonatal rats compared with adolescent rats. We estimated neuronal activity in the cortex, hippocampus and thalamus after propofol administration with or without bumetanide, an NKCC1 inhibitor, by immunostaining of phosphorylated cyclic adenosine monophosphate-response element binding protein (pCREB). We studied effects of bumetanide on propofol-induced LORR and immobilizing actions in postnatal day 7 and 28 (P7 and P28) rats. The pCREB expression in the cortex (P = 0.001) and hippocampus (P = 0.01) was significantly greater in the rats receiving propofol only than in the rats receiving propofol plus bumetanide at P 7. Propofol-induced LORR or immobilizing effects did not differ significantly between P7 and P28. Bumetanide significantly enhanced propofol-induced LORR (P = 0.031) but not immobilization in P7 rats. These results are partially consistent with our hypothesis. They suggest that propofol may activate the rostral but not caudal central nervous system dependently on NKCC1, and these differential actions may underlie the different properties of sedative and immobilizing actions observed in neonatal rats.

Motor Training Promotes Both Synaptic and Intrinsic Plasticity of Layer II/III Pyramidal Neurons in the Primary Motor Cortex

Motor skill training induces structural plasticity at dendritic spines in the primary motor cortex (M1). To further analyze both synaptic and intrinsic plasticity in the layer II/III area of M1, we subjected rats to a rotor rod test and then prepared acute brain slices. Motor skill consistently improved within 2 days of training. Voltage clamp analysis showed significantly higher α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid/N-methyl-d-aspartate (AMPA/NMDA) ratios and miniature EPSC amplitudes in 1-day trained rats compared with untrained rats, suggesting increased postsynaptic AMPA receptors in the early phase of motor learning. Compared with untrained controls, 2-days trained rats showed significantly higher miniature EPSC amplitude and frequency. Paired-pulse analysis further demonstrated lower rates in 2-days trained rats, suggesting increased presynaptic glutamate release during the late phase of learning. One-day trained rats showed decreased miniature IPSC frequency and increased paired-pulse analysis of evoked IPSC, suggesting a transient decrease in presynaptic γ-aminobutyric acid (GABA) release. Moreover, current clamp analysis revealed lower resting membrane potential, higher spike threshold, and deeper afterhyperpolarization in 1-day trained rats—while 2-days trained rats showed higher membrane potential, suggesting dynamic changes in intrinsic properties. Our present results indicate dynamic changes in glutamatergic, GABAergic, and intrinsic plasticity in M1 layer II/III neurons after the motor training.

Static and Dynamical Properties of the Spin-1/2 Equilateral Triangular-Lattice Antiferromagnet Ba_{3}CoSb_{2}O_{9}

We present single-crystal neutron scattering measurements of the spin-1/2 equilateral triangular-lattice antiferromagnet Ba_{3}CoSb_{2}O_{9}. Besides confirming that the Co^{2+} magnetic moments lie in the ab plane for zero magnetic field and then determining all the exchange parameters of the minimal quasi-2D spin Hamiltonian, we provide conclusive experimental evidence of magnon decay through observation of intrinsic line broadening. Through detailed comparisons with the linear and nonlinear spin-wave theories, we also point out that the large-S approximation, which is conventionally employed to predict magnon decay in noncollinear magnets, is inadequate to explain our experimental observation. Thus, our results call for a new theoretical framework for describing excitation spectra in low-dimensional frustrated magnets under strong quantum effects.

Thoracic paravertebral block reduced the incidence of chronic postoperative pain for more than 1 year after breast cancer surgery

Background

Thoracic paravertebral block (TPVB) is used to reduce pain after breast cancer surgery (BCS), but the pain-reduction effects more than 1 year after surgery are unclear.

Findings

Fifty-one patients underwent BCS at the Niigata City General Hospital from December 2009 through March 2010. To evaluate the long-term effects of TPVB in the reduction of chronic pain after BCS, we retrospectively reviewed the anesthesia charts and medical records of these patients and conducted telephone surveys regarding postoperative pain 13–17 months after surgery in 46 of these patients. Among the 46 patients enrolled in this study, 17 experienced chronic pain. There was a significant difference in the percentage of patients that received TPVB among those with and without chronic pain (patients with chronic pain 5/17 (29.4 %), patients without chronic pain 18/29 (62.1 %), p = 0.039). The pain score 3–6 h after surgery was significantly higher in the patients with chronic pain than without (p = 0.016). Bivariate logistic regression revealed that TPVB and pain score 3–6 h after surgery were independent predictive factors of chronic pain after BCS.

Conclusions

These results indicate that TPVB has the potential to reduce chronic pain for more than 1 year after BCS.

Pectoral nerve block combined with general anesthesia for breast cancer surgery: a retrospective comparison

Background

Acute postoperative pain is an integral risk factor in the development of chronic pain after breast cancer surgery (BCS). Pectoral nerve block (PECSB) has been recently reported as an analgesic method for BCS. Here, we retrospectively compared intraoperative opioid requirement, postoperative pain after BCS, and incidence of postoperative nausea and vomiting (PONV) in patients who underwent BCS under total intravenous anesthesia (TIVA) with or without PECSB.

Findings

We reviewed anesthesia charts and medical records of 146 patients who underwent BCS at Niigata University Medical and Dental Hospital from January 2013 to March 2014; 36 patients were included in the TIVA group, and 35 patients were included in the TIVA + PECSB group. Intraoperative remifentanil requirements were significantly lower in the TIVA + PECSB group than in the TIVA group, and the cumulative distribution of remifentanil was reduced in patients who received PECSB (TIVA: 10.9 ± 2.9 μg/kg/h; TIVA + PECSB: 7.3 ± 3.3 μg/kg/h; p < 0.001). Postoperative pain scores during the 48 h after surgery were significantly lower in the TIVA + PECSB group than in the TIVA group (TIVA: 2 [1–5]; TIVA + PECSB: 1 [0–5]; p = 0.03). However, administration of fentanyl during operation, percentage of patients requiring supplemental analgesics, and incidence of PONV were not significantly different between groups.

Conclusions

PECSB significantly reduced intraoperative remifentanil usage and postoperative pain. However, the requirement for postoperative supplemental analgesics and the incidence of PONV did not differ. These data suggested that PECSB may be useful for perioperative pain management in patients undergoing BCS.

Intrathecal morphine versus epidural ropivacaine infusion for analgesia after Cesarean section: a retrospective study

Background

Analgesia after Cesarean delivery (CD) requires early ambulation to prevent thromboembolic disease and to facilitate baby care. We retrospectively reviewed anesthesia charts and medical records of patients who underwent CD to compare the efficacy of spinal anesthesia supplemented with intrathecal morphine hydrochloride (ITM) and combined spinal–epidural anesthesia followed by opioid-free epidural analgesia (CSEA-EDA).

Findings

All subjects underwent CD at Nagaoka Chuo General Hospital between February 2012 and January 2013. Patient characteristics, time to first analgesic rescue after CD, and analgesic use after CD were examined. Incidences of postural hypotension, lower extremity numbness/weakness, postoperative nausea/vomiting (PONV), and pruritus were also examined for 48 h after CD. Average time to first analgesic use after CD (ITM 25.13 ± 16.07 h, CSEA-EDA 22.42 ± 16.27 h, p = 0.521) and cumulative probability of rescue analgesic use (p = 0.139 by log-rank test) were comparable between groups. However, average analgesic use within 24 h was lower in the ITM group (0.75 ± 1.05 times) than in the CSEA-EDA group (1.52 ± 1.72 times, p = 0.0497). Numbness or motor weakness in lower extremities only occurred in the CSEA-EDA group, and pruritus only occurred in the ITM group.

Conclusions

The results of this study suggest that ITM is better than CSEA-EDA for anesthesia following CD with regard to pain control. Also, ITM would be advantageous for early ambulation following CD because of lower incidence of numbness and motor weakness in lower extremities compared to CSEA-EDA.

Tranexamic acid evokes pain by modulating neuronal excitability in the spinal dorsal horn

Tranexamic acid (TXA) is an antifibrinolytic agent widely used to reduce blood loss during surgery. However, a serious adverse effect of TXA is seizure due to inhibition of γ-aminobutyric acid (GABA) and glycine receptors in cortical neurons. These receptors are also present in the spinal cord, and antagonism of these receptors in spinal dorsal horn neurons produces pain-related phenomena, such as allodynia and hyperalgesia, in experimental animals. Moreover, some patients who are injected intrathecally with TXA develop severe back pain. However, the effect of TXA on spinal dorsal horn neurons remain poorly understood. Here, we investigated the effects of TXA by using behavioral measures in rats and found that TXA produces behaviors indicative of spontaneous pain and mechanical allodynia. We then performed whole-cell patch-clamp experiments that showed that TXA inhibits GABA_A and glycine receptors in spinal dorsal horn neurons. Finally, we also showed that TXA facilitates activation of the extracellular signal-regulated kinase in the spinal cord. These results indicated that TXA produces pain by inhibiting GABA_A and glycine receptors in the spinal dorsal horn.

Spinal cord stimulation modulates supraspinal centers of the descending antinociceptive system in rats with unilateral spinal nerve injury

BACKGROUND

The descending antinociceptive system (DAS) is thought to play crucial roles in the antinociceptive effect of spinal cord stimulation (SCS), especially through its serotonergic pathway. The nucleus raphe magnus (NRM) in the rostral ventromedial medulla is a major source of serotonin [5-hydroxytryptamine (5-HT)] to the DAS, but the role of the dorsal raphe nucleus (DRN) in the ventral periaqueductal gray matter is still unclear. Moreover, the influence of the noradrenergic pathway is largely unknown. In this study, we evaluated the involvement of these serotonergic and noradrenergic pathways in SCS-induced antinociception by behavioral analysis of spinal nerve-ligated (SNL) rats. We also investigated immunohistochemical changes in the DRN and locus coeruleus (LC), regarded as the adrenergic center of the DAS, and expression changes of synthetic enzymes of 5-HT [tryptophan hydroxylase (TPH)] and norepinephrine [dopamine β-hydroxylase (DβH)] in the spinal dorsal horn.

RESULTS

Intrathecally administered methysergide, a 5-HT1- and 5-HT2-receptor antagonist, and idazoxan, an α2-adrenergic receptor antagonist, equally abolished the antinociceptive effect of SCS. The numbers of TPH-positive serotonergic and phosphorylated cyclic AMP response element binding protein (pCREB)-positive neurons and percentage of pCREB-positive serotonergic neurons in the DRN significantly increased after 3-h SCS. Further, the ipsilateral-to-contralateral immunoreactivity ratio of DβH increased in the LC of SNL rats and reached the level seen in naïve rats, even though the number of pCREB-positive neurons in the LC was unchanged by SNL and SCS. Moreover, 3-h SCS did not increase the expression levels of TPH and DβH in the spinal dorsal horn.

CONCLUSIONS

The serotonergic and noradrenergic pathways of the DAS are involved in the antinociceptive effect of SCS, but activation of the DRN might primarily be responsible for this effect, and the LC may have a smaller contribution. SCS does not potentiate the synthetic enzymes of 5HT and norepinephrine in the neuropathic spinal cord.

Constraints on new gravitylike forces in the nanometer range

We report on a new constraint on gravitylike short-range forces, in which the interaction charge is mass, obtained by measuring the angular distribution of 5 Å neutrons scattering off atomic xenon gas. Around 10^{7} scattering events were collected at the 40 m small angle neutron scattering beam line located at the HANARO research reactor of the Korean Atomic Energy Research Institute. The extracted coupling strengths of new forces in the Yukawa-type parametrization are g[over ^]^{2}=(0.2±6.8±2.0)×10^{-15}  GeV^{-2} and g[over ^]^{2}=(-5.3±9.0_{-2.8}^{+2.7})×10^{-17}  GeV^{-2} for interaction ranges of 0.1 and 1.0 nm, respectively. These strengths correspond to 95% confidence level limits of g^{2}<(1.4±0.2)×10^{-14}  GeV^{-2} and g^{2}<(1.3±0.2)×10^{-16}  GeV^{-2}, improving the current limits for interaction ranges between 4 and 0.04 nm by a factor of up to 10.

Estrogen via estrogen receptor beta partially inhibits mandibular condylar cartilage growth

OBJECTIVE

Temporomandibular joint (TMJ) diseases predominantly afflict women, suggesting a role for female hormones in the disease process. However, little is known about the role of estrogen receptor (ER) signaling in regulating mandibular condylar cartilage growth. Therefore, the goal of this study was to examine the effects of altered estrogen levels on the mandibular condylar cartilage in wild type (WT) and ER beta Knockout (KO) mice.

MATERIALS AND METHODS

21-day-old female WT (n = 37) and ER beta KO mice (n = 36) were either sham operated or ovariectomized, and treated with either placebo or estradiol. The mandibular condylar cartilage was evaluated by histomorphometry, proliferation was analyzed by double ethynyl-2'-deoxyuridine/bromodeoxyuridine (EdU/BrdU) labeling, and assays on gene and protein expression of chondrocyte maturation markers were performed.

RESULTS

In WT mice, ovariectomy caused a significant increase in mandibular condylar cartilage cell numbers, a significant increase in Sox9 expression and a significant increase in proliferation compared with sham operated WT mice. In contrast, ovariectomy did not cause any of these effects in the ER beta KO mice. Estrogen replacement treatment in ovariectomized WT mice caused a significant decrease in ER alpha expression and a significant increase in Sost expression compared with ovariectomized mice treated with placebo. Estrogen replacement treatment in ovariectomized ER beta KO mice caused a significant increase in Col2 expression, no change in ER alpha expression, and a significant increase in Sost expression.

CONCLUSION

Estrogen via ER beta inhibits proliferation and ER alpha expression while estrogen independent of ER beta induces Col2 and Sost expression.

Prevalence and associated factors of depressive state among pulmonary tuberculosis patients in Manila, The Philippines

SETTING

Both depression and tuberculosis (TB) are global public health problems that have a substantial impact on human health. However, depressive state among TB patients has not been well investigated in the Philippines.

OBJECTIVE

To assess depressive state among pulmonary tuberculosis (PTB) patients and to identify factors associated with depressive state in Manila, the Philippines.

DESIGN

A cross-sectional survey of PTB patients was conducted at 10 public health centres and two non-government organisation clinics providing directly observed treatment in District I, Tondo, Manila. Face-to-face interviews with 561 PTB patients using a structured questionnaire were conducted.

RESULTS

Depressive state was observed in 16.8% of the participants. Logistic regression analysis indicated that body mass index < 18.5 kg/m(2), marital status of cohabitation compared with married, four or more symptoms, four or more adverse drug reactions, grade 3 or higher on the Medical Research Council dyspnoea scale and low perceived confidant social support were significantly associated with depressive state.

CONCLUSION

Depressive state among PTB patients in economically depressed areas is common, and screening for depression in the primary care setting can identify patients who need support and treatment, especially for malnourished patients and those with poor social support.

Relationship between ventral lumbar disc protrusion and contrast medium leakage during sympathetic nerve block

Ventral disc protrusions have been neglected because they are asymptomatic. Lumbar sympathetic nerve block (LSNB) is one of the clinical choices for refractory low back pain treatment. Leakage of the contrast medium may occur and lead to complications, especially when using a neurolytic agent. In this study, we retrospectively reviewed the magnetic resonance images (MRIs) of 52 consecutive patients with refractory low back pain due to lumbar spinal canal stenosis who underwent LSNB, and graded ventral disc protrusion at the L1/2 to L5/S1 vertebral discs on a three-point scale (grade 0 = no protrusion, grade 1 = protrusion without migration, grade 2 = protrusion with migration). We also determined if there was leakage of contrast medium in LSNB. Ventral disc protrusion was observed in all patients, and 75 % (39/52) had grade 2 protrusion in the L1/2-L3/4 vertebral discs. Moreover, the incidence of contrast medium leakage was significantly higher at the vertebrae that had grade 2 protrusion than at those with less protrusion. We revealed a higher incidence of ventral disc protrusion of the lumbar vertebrae than previously reported, and that the incidence of leakage in LSNB increased when ventral disc protrusion was present. To avoid complications, attention should be paid to ventral disc protrusions before performing LSNB.

Observation of the spatial distribution of gravitationally bound quantum states of ultracold neutrons and its derivation using the Wigner function

Ultracold neutrons (UCNs) can be bound by the potential of terrestrial gravity and a reflecting mirror. The wave function of the bound state has characteristic modulations. We carried out an experiment to observe the vertical distribution of the UCNs above such a mirror at the Institut Laue-Langevin in 2011. The observed modulation is in good agreement with that prediction by quantum mechanics using the Wigner function. The spatial resolution of the detector system is estimated to be 0.7  μm. This is the first observation of gravitationally bound states of UCNs with submicron spatial resolution.

Role of nerve growth factor-tyrosine kinase receptor A signaling in paclitaxel-induced peripheral neuropathy in rats

The mechanisms underlying paclitaxel-induced peripheral neuropathy remain unknown. Nerve growth factor (NGF) is a representative neurotrophic factor that maintains neuronal function, promotes survival, and mediates neuropathic pain. We investigated expression levels of NGF and its receptors in the dorsal root ganglia (DRG) and spinal dorsal horn (DH) following paclitaxel treatment. Intraperitoneal (I.P.) administration of paclitaxel induced significant mechanical hypersensitivity and cold allodynia in rats, significantly increased the expression of NGF and its receptor tyrosine kinase receptor A (trkA) in the DRG, and increased NGF expression in the DH. In contrast, paclitaxel treatment did not alter the mRNA levels of NGF or its receptors in the DRG, DH, sciatic nerve, or hindpaw skin. Moreover, expression of NEDD4-2, a negative regulator of trkA, was significantly increased in the DRG of paclitaxel-treated rats. Intrathecal (I.T.) administration of the tyrosine kinase receptor inhibitor k252a significantly alleviated mechanical hypersensitivity in paclitaxel-treated rats. Our results suggest that NGF-trkA signaling is involved in mechanical allodynia in paclitaxel-induced neuropathy.

Experimental validation of a novel compact focusing scheme for future energy-frontier linear lepton colliders

A novel scheme for the focusing of high-energy leptons in future linear colliders was proposed in 2001 [P. Raimondi and A. Seryi, Phys. Rev. Lett. 86, 3779 (2001)]. This scheme has many advantageous properties over previously studied focusing schemes, including being significantly shorter for a given energy and having a significantly better energy bandwidth. Experimental results from the ATF2 accelerator at KEK are presented that validate the operating principle of such a scheme by demonstrating the demagnification of a 1.3 GeV electron beam down to below 65 nm in height using an energy-scaled version of the compact focusing optics designed for the ILC collider.

Amyloid-β₂₅₋₃₅ induces impairment of cognitive function and long-term potentiation through phosphorylation of collapsin response mediator protein 2

Alzheimer's disease (AD) is characterized by amyloid-β (Aβ) protein and tau deposition in the brain. Numerous studies have reported a central role of Aβ in the development of AD, but the pathogenesis is not well understood. Collapsin response mediator protein 2 (CRMP2), an intracellular protein mediating a repulsive axon guidance molecule, Semaphorin3A, is also accumulated in neurofibrillary tangles in AD brains. To gain insight into the role of CRMP2 phosphorylation in AD pathogenesis, we investigated the effects of Aβ neurotoxicity in CRMP2 phosphorylation-deficient knock-in (crmp2(ki/ki)) mice, in which the serine residue at 522 was replaced with alanine. Intracerebroventricular (i.c.v.) injection of Aβ₂₅₋₃₅ peptide, a neurotoxic fragment of Aβ protein, to wild-type (wt) mice increased hippocampal phosphorylation of CRMP2. Behavioral assessment revealed that i.c.v. injection of Aβ₂₅₋₃₅ peptide caused impairment of novel object recognition in wt mice, while the same peptide did not in crmp2(ki/ki) mice. In electrophysiological recording, wt and crmp2(ki/ki) mice have similar input-output basal synaptic transmission and paired-pulse ratios. However, long-term potentiation was impaired in hippocampal slices of Aβ₂₅₋₃₅ peptide-treated wt but not those of crmp2(ki/ki). Our findings indicate that CRMP2 phosphorylation is required for Aβ-induced impairment of cognitive memory and synaptic plasticity.

Phasic synaptic incorporation of GluR2-lacking AMPA receptors at gonadotropin-releasing hormone neurons is involved in the generation of the luteinizing hormone surge in female rats

Reproductive success depends on a robust and appropriately timed preovulatory luteinizing hormone (LH) surge, which is induced by the activation of gonadotropin-releasing hormone (GnRH) neurons in response to positive feedback from increasing estrogen levels. Here we document an increase in postsynaptic GluR2-lacking Ca2+ -permeable AMPA-type glutamate receptors (CP-AMPARs) at synapses on GnRH neurons on the day of proestrus in rats, coincident with the increase in estrogen levels. Functional blockade of CP-AMPARs depressed the synaptic responses only on the day of proestrus and concomitantly attenuated the LH surge. Thus, the phasic synaptic incorporation of postsynaptic CP-AMPARs on GnRH neurons is involved in the generation of the LH surge.

Anatomical study of superior cluneal nerve entrapment

OBJECT

Entrapment of the superior cluneal nerve (SCN) in an osteofibrous tunnel in the space surrounded by the iliac crest and the thoracolumbar fascia is a cause of low-back pain (LBP). Several anatomical and surgical reports describe SCN entrapment as a cause of LBP, and a recent clinical study reported that patients with suspected SCN disorder constitute approximately 10% of the patients suffering from LBP and/or leg symptoms. However, a detailed anatomical study of SCN entrapment is rare. The purpose of this study was to investigate the courses of SCN branches and to ascertain the frequency of SCN entrapment.

METHODS

Branches of the SCN were dissected in 109 usable specimens (54 on the right side and 55 on the left side) obtained in 59 formalin-preserved cadavers (average age at death 84.8 years old). All branches were exposed at the points where they perforated the thoracolumbar fascia. The presence or absence of an osteofibrous tunnel was ascertained and, if present, the entrapment of the branches in the tunnel was determined.

RESULTS

Of 109 specimens, 61 (56%) had at least 1 branch running through an osteofibrous tunnel. Forty-two medial (39%), 30 intermediate (28%), and 14 lateral (13%) SCN branches passed through such a tunnel. Of these, only 2 medial branches had obvious entrapment in an osteofibrous tunnel. There were several patterns for the SCN course through the tunnel: medial branch only (n = 25), intermediate branch only (n = 11), lateral branch only (n = 4), medial and intermediate branches (n = 11), medial and lateral branches (n = 2), intermediate and lateral branches (n = 4), and all branches (n = 4).

CONCLUSIONS

Several anatomical variations of the running patterns of SCN branches were detected. Entrapment was seen only in the medial branches. Although obvious entrapment of the SCN is rare, it may cause LBP.

Lipopolysaccharide of Aggregatibacter actinomycetemcomitans up-regulates inflammatory cytokines, prostaglandin E2 synthesis and osteoclast formation in interleukin-1 receptor antagonist-deficient mice

BACKGROUND AND OBJECTIVE

The interleukin (IL)-1 receptor antagonist (Ra) binds to IL-1 receptors and inhibits IL-1 activity. However, it is unclear whether the IL-1Ra plays a protective role in periodontal disease. The purpose of this study was to compare IL-1Ra knockout (KO) and wild-type (WT) mice in regard to proinflammatory cytokine production, osteoclast formation and bone resorption in response to periodontal bacterial lipopolysaccharide (LPS).

MATERIAL AND METHODS

Peritoneal macrophages (Mφs) were obtained from 13-wk-old IL-1Ra KO and WT mice. Peritoneal Mφs were cultured with or without 10 μg/mL of Aggregatibacter actinomycetemcomitans LPS for 24 h. The levels of IL-1alpha (IL-1α), IL-1beta (IL-1β), tumor necrosis factor-α (TNF-α) and IL-6 were measured in periotoneal Mφs supernatant fluid (PM-SF) using an ELISA. Bone marrow cells were obtained from the mice and stimulated with PM-SF for 9 d, then stained with TRAP. The frequency of TRAP-positive multinucleated giant cell formation was calculated based on a fusion index. PM-SF-stimulated calvarial bone resorption was analyzed using micro-computed tomography, and calvarial histological analysis was performed using hematoxylin and eosin and TRAP staining. The expression of cyclooxygenase-2 (Cox2), prostanoid receptor EP4 (Ep4) and Rank mRNAs in bone marrow cells were measured using real-time quantitative PCR, while prostaglandin E2 (PGE2 ) production was determined by ELISA.

RESULTS

The levels of IL-1α, IL-1β, TNF-α and IL-6 in IL-1Ra KO mice PM-SF stimulated with A. actinomycetemcomitans LPS were significantly increased by approximately 4- (p < 0.05), 5- (p < 0.05), 1.3- (p < 0.05) and 6- (p < 0.05) fold, respectively, compared with the levels in WT mice. Moreover, osteoclast formation, expression of Rank, Ep4 and Cox2 mRNAs and production of PGE2 were significantly increased by approximately 2- (p < 0.05), 1.6- (p < 0.05), 2.5- (p < 0.05), 1.6- (p < 0.05) and 1.9- (p < 0.05) fold, respectively, in IL-1Ra KO mice stimulated with A. actinomycetemcomitans LPS compared with WT mice.

CONCLUSION

IL-1Ra regulates IL-1 activity and appears to reduce the levels of other inflammatory cytokines, including TNF-α and IL-6, while it also reduces expression of the EP4 receptor related to prostanoid sensitivity and osteoclast formation. These results suggest that IL-1Ra is an important molecule for inhibition of inflammatory periodontal bone resorption.

Environmental lithium exposure in the North of Chile--I. Natural water sources

Lithium as an essential element for human life is still a subject of controversy. However, it is accepted that it does have profound neurological effects and is a valuable treatment for bipolar disease. Generally, it occurs in barely trace amounts in groundwater with few major exceptions. One of these is the Northern area of Chile where all potable water and many of the food stuffs contain high levels of lithium; between 100 and 10,000 times higher than most rivers in North America. Inevitably, the local population has been exposed to these levels in their drinking water for as long as the region has been populated. The present report details lithium levels in all the surface water sources of Northern Chile with comparison to that elsewhere. The implications for the local population are discussed and their situation compared to those exposed to other sources of lithium pollution.