Contribution of TRPV1 Receptor–Expressing Fibers to Spinal Ventral Root After-Discharges and Mechanical Hyperalgesia in a Spared Nerve Injury (SNI) Rat Model

Neuropathic pain induces allodynia and hyperalgesia. In the spared nerve injury (SNI) model, marked mechanical hyperalgesia is manifested as prolongation of the duration of paw withdrawal after pin stimulation. We have previously reported that spinal ventral root discharges (after-discharges) after cessation of noxious mechanical stimulation applied to the corresponding hindpaw were prolonged in anesthetized spinalized rats. Since these after-discharges occurred through transient receptor potential (TRP) V1–positive fibers, these fibers could contribute to mechanical hyperalgesia. Therefore, we examined whether selective deletion of TRPV1-positive fibers by resiniferatoxin, an ultrapotent TRPV1 agonist, would affect the behavioral changes and ventral root discharges in SNI rats. Mechanical allodynia in the von Frey test, mechanical hyperalgesia after pin stimulation, and enhancement of ventral root discharges, but not thermal hyperalgesia in the plantar test, appeared in Wistar rats with SNI. Mechanical hyperalgesia was abolished by treatment with resiniferatoxin, whereas mechanical allodynia was not affected. Moreover, resiniferatoxin eliminated after-discharges completely. These results show that TRPV1-positive fibers do not participate in the mechanical allodynia caused by sensitization of Aβ-fibers, but contribute to the enhancement of after-discharges and mechanical hyperalgesia following SNI. It is suggested that the mechanisms responsible for generating mechanical allodynia differ from those for prolongation of mechanical hyperalgesia.     

Previously undescribed palpebral branch from the infraorbital canal: Application to surgery of the eyelid and treatment of orbital floor fractures

The sensory innervation of the inferior eyelid is mainly derived from the inferior palpebral branch (IPb) of the infraorbital nerve (ION). This study aimed to investigate another, to our knowledge, previously unknown branch, and elucidate its location and distribution. Twelve sides from seven fresh frozen cadaveric Caucasian heads were used in this study. The specimens were derived from two male and four female adult cadavers age. The diameter of the IPb of the ION (D1) and branch arising from the upper wall of the infraorbital canal (D2), and distance between the branching points of this branch and the anterior border of the orbit floor (L1) was measured. A branch to the lower eyelid was found arising from the infraorbital canal on the majority of sides. D1 ranged from 0.4 to 1.1 mm. The branch arising from the upper wall of the infraorbital canal was found 10 sides (83%). D2 ranged 0.6 to 1.0 mm. L1 ranged from 10.2 to 19.8 mm. All of the branches arising from the upper wall of the infraorbital canal (10 sides) primarily innervated to the inferior eyelid. We suggest this branch should be named the “posterior IPb” of the ION. Knowledge of this branch might decrease sensory loss following invasive procedures of the lower orbit. Clin. Anat. 30:835–838, 2017. © 2017Wiley Periodicals, Inc.     

Neuroapraxia del nervio hipogloso tras hemiartroplastia de hombro

We report a case of hypoglossal nerve damage after shoulder hemiarthroplasty with the patient in «beach chair» position, performed with general anesthesia with orotracheal intubation, and without complications. An ultrasound-guided interscalene block was previously performed in an alert patient. After the intervention, the patient showed clinical symptomatology compatible with paralysis of the right hypoglossal nerve that completely disappeared after 4 weeks. Mechanisms such as hyperextension of the neck during intubation, endotracheal tube cuff pressure, excessive hyperextension, or head lateralization during surgery have been described as causes of this neurological damage. We discuss the causes, the associated factors and suggest preventive measures.     

高血压心肌肥厚患者心脏交感神经分布与勿动蛋白A表达变化的关系

目的探讨高血压心肌肥厚患者心脏交感神经分布与神经元轴突生长抑制因子勿动蛋白A(neurite out-growth inhibitor-A,Nogo-A)的表达变化。方法从我院老年患者尸体标本库中,随机入选男性高血压患者10例,并根据患者去世前1周心脏超声结果分为心肌肥厚组4例和非心肌肥厚组6例。检测超声心动图,并计算左心室重量指数。免疫组织化学分析测定酪氨酸羟化酶(tyrosine hydroxylase,TH)与Nogo-A的表达。结果与非心肌肥厚组比较,心肌肥厚组患者室间隔厚度、左心室后壁厚度、左心室重量指数明显升高(P<0.05);心肌肥厚组患者心肌TH阳性表达明显降低[(6.35±3.85)%υs(22.17±8.19)%,P<0.05],Nogo A表达明显增加[(11.34±7.16)%υs(2.17±4.10)%,P<0.05]。心肌肥厚患者心肌Nogo-A表达与心肌TH表达呈负相关(r=-0.33,P<0.05)。结论老年高血压心肌肥厚患者心肌交感神经分布减低,然而心肌神经元轴突生长抑制因子Nogo-A表达增加,两者间存在密切相关性。     

Viscoelastic properties of the autologous bypass grafts: A comparative study among the small saphenous vein and internal thoracic artery

Internal thoracic artery (ITA) and small saphenous vein (SSV) are two viable conduits for coronary artery bypass grafts. The aim of this study was to investigate the viscoelastic behavior of the small saphenous vein and internal thoracic artery under compressive and tensile loadings at body temperature. The dynamic mechanical analysis was used to measure the viscoelastic properties of the ITA and SSV at both the desired temperature and load frequency range. Storage modulus, loss modulus as well as phase angle of both the blood vessels were measured at the temperature of 37 ± 1 °C and under a sinusoidal load with the frequency range of 1–2 Hz. The mean storage and loss modulus of the SSV were both higher than that of the ITA. Furthermore, the SSV showed a higher stiffness and internal friction compared to those values under the tensile load. While ITA was stiffer under the tensile load, no considerable difference was observed among the compressive and tensile loss modulus. A more intense viscous behavior was observed under the radial direction. The results also revealed that the SSV has much higher stiffness whereas less viscous behavior compared to the ITA, especially in the radial direction. The results may have implications not only for understanding of the viscoelastic time-dependent mechanical behavior of the ITA and SSV but also for tissue engineering applications to make scaffolds according to the real time-dependent viscoelastic mechanical properties of these arteries and veins.     

Positive AMPA receptor modulation in the treatment of neuropsychiatric disorders: A long and winding road

Glutamatergic transmission is widely implicated in neuropsychiatric disorders, and the discovery that ketamine elicits rapid-acting antidepressant effects by modulating α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor (AMPAR) signaling has spurred a resurgence of interest in the field. This review explores agents in various stages of development for neuropsychiatric disorders that positively modulate AMPARs, both directly and indirectly. Despite promising preclinical research, few direct and indirect AMPAR positive modulators have progressed past early clinical development. Challenges such as low potency have created barriers to effective implementation. Nevertheless, the functional complexity of AMPARs sets them apart from other drug targets and allows for specificity in drug discovery. Additional effective treatments for neuropsychiatric disorders that work through positive AMPAR modulation may eventually be developed.     

Peripheral and local anaesthetic techniques for paediatric surgery

Peripheral nerve blocks (PNBs) in paediatric patients are usually used as an adjunct to general anaesthesia, providing intra- and postoperative analgesia. These blocks provide good-quality analgesia preventing morbidity related to pain and reducing adverse effects from systemic analgesics. PNBs aid early patient recovery and discharge, which is essential in day-case surgery. Like all invasive techniques, PNBs are associated with complications and adverse effects. They should therefore be performed only after careful analysis of the risk:benefit ratio for each child. This article discusses a general approach to PNBs in children. It covers a small selection of limb and trunk blocks, and discusses the benefit of ultrasound guidance.     

Catalyst‐Free Ring Opening Synthesis of Biodegradable Poly(ester‐urethane)s Using Isosorbide Bio‐Based Initiator

Polycaprolactones are obtained via ring opening polymerization of ε‐caprolactone in catalyst‐free condition. The polymerization is initiated in bulk, using isosorbide‐based amino‐alcohol as a biosourced initiator. The ratio of initiator to ε‐caprolactone, as well as to temperature, is optimized in order to tune the hydroxyl number (Nr. OH) and the average molecular weight of the polymers. In addition, these biocompatible polyesters are used as soft‐block to prepare thermoplastic poly(esterurethane)s elastomers via a simple one‐pot catalyst‐free polymerization. The successful synthesis of poly(esterurethane)s is confirmed by Fourier transform‐infrared spectroscopy, and the thermal properties are studied by differential scanning calorimetry. These novel materials exhibit glass transition temperatures ranging from 7 to 38 °C. The biodegradability of these elastomers is evaluated by enzymatic degradation tests performed at rt in phosphate buffer solution (pH ≈ 7.4). The mass loss of polymer films is around 3% after 4 weeks. Scan electron as well as atomic force microscopies are used to show the degradation patterns.     

Microsurgical anatomy of the abducens nerve

The aim of this study is to demonstrate and review the detailed microsurgical anatomy of the abducens nerve and surrounding structures along its entire course and to provide its topographic measurements. Ten cadaveric heads were examined using ×3 to ×40 magnification after the arteries and veins were injected with colored silicone. Both sides of each cadaveric head were dissected using different skull base approaches to demonstrate the entire course of the abducens nerve from the pontomedullary sulcus to the lateral rectus muscle. The anatomy of the petroclival area and the cavernous sinus through which the abducens nerve passes are complex due to the high density of critically important neural and vascular structures. The abducens nerve has angulations and fixation points along its course that put the nerve at risk in many clinical situations. From a surgical viewpoint, the petrous tubercle of the petrous apex is an intraoperative landmark to avoid damage to the abducens nerve. The abducens nerve is quite different from the other nerves. No other cranial nerve has a long intradural path with angulations and fixations such as the abducens nerve in petroclival venous confluence. A precise knowledge of the relationship between the abducens nerve and surrounding structures has allowed neurosurgeon to approach the clivus, petroclival area, cavernous sinus, and superior orbital fissure without surgical complications. Clin. Anat. 25:1030–1042, 2012. © 2012 Wiley Periodicals, Inc.